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Recent Progress in the Physiology and Biochemistry of the Liver
Recent Progress in the Physiology and Biochemistry of the Liver SMITH FREEMAN, PH.D., M.D.*
CIRCULATION
and biochemical aspects of hepatic function are extremely numerous and diversified. This relatively huge organ is strategically situated to exert both physical and chemical influence on the volume and composition of the circulating blood. Through its portal system must pass all of the blood from the intestines, spleen and a portion of the stomach. In addition to this large volume, low pressure system of blood poor in oxygen, the liver receives approximately one-fourth of its blood supply through the hepatic and gastroduodenal arteries. Within the sinusoids of the liver, blood may temporarily stagnate in certain areas while others manifest an active circulation. l In certain species, it seems probable that the intrahepatic circulation may be altered at times by a system of shunts that enables blood to pass from the portal vein to the inferior vena cava without passage through the sinusoids. 2 PHYSIOLOGICAL
Hormonal Effects It has been demonstrated 3 that the inflow, outflow and storage of blood in the perfused isolated liver is influenced by epinephrine and acetylcholine. The response of the liver to these stimuli will depend upon its state at the time of stimulation as well as on the strength of the stimulus. Increased blood flow through the splanchnic and portal vessels has been reported 4 to follow the administration of epinephrine and in association with the hypoglycemia that occurs approximately forty-five minutes after insulin injection. There are differences in the effects of epinephrine on blood flow through the liver as reported by various investigators. However, many of these experiments are not comFrom the Department of Biochemistry, Northwestern University Medical School, Chicago.
* Professor
of Biochernistry, Northwestern University Medical School. 109
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parable, as the experimental conditions, dosages and routes of administration differed. Evidence of increased rate of blood flow through the liver following epinephrine is compatible with a reduction of the reservoir of blood in the splanchnic system and liver. Shrinkage of these organs as well as acceleration of the mobilization and transportation of glucose are all parts of the organism's preparedness for flight or fight. Nervous Stimuli
The generous plexus of fibers from the sympathetic nervous system that surrounds the hepatic artery makes apparent a rich source of nervous stimuli that may alter the vasomotor tone of the hepatic circulation. Their stimulation reduced the vascular bed in the liver of several species as judged by the behavior of Diodrast injected through the portal system and caused intrahepatic vessels of the portal system to constrict. 5 This portal constriction was associated with a greater flow in the shorter pathways through the liver and would provide an alternate route to the final common pathway of arterial and venous blood which entails passage of blood though the sinusoids of the liver lobule.!' 2,3 Reservoir Function
The normal liver is capable of some expansion and contraction depending upon the extent of its engorgement with blood. Extrahepatic factors concerned in its circulation include the systemic circulation, the metabolic activity of this organ and the vasomotor tone of the splanchnic vessels; low pressures, large volume and a marked variability in tone characterize this vascular bed. Minor variations in intra-abdominal volume and pressure associated with normal respiratory movements contribute materially to the flow of blood in the portal system and through the liver. The temporary storage of blood is a normal function of the liver. It seems well established that a sphincter mechanism capable of trapping blood within the liver and splanchnic area exists in the hepatic veins of· the dog and other species. 5 , 6,7 There is no direct evidence that such a spincter mechanism exists in man. Secondary Surgical Shock
Studies have been made regarding the extent to which an exaggerated response by a sphincter mechanism may contribute to the findings and mortality in experimental shock due to controlled hemorrhage. Studies indicate that the maintenance 'of an' adequate portal circulation and oxygen supply to the liver enabled recovery from experimental shock to occur more frequently than was otherwise the case. 8 That the splanchnic engorgement and congestion of the gastrointestinal tract were not of primary significance in the irreversibility of shock was indicated by the
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findings that diverting blood to the vena cava through a portacaval anastomosis did not alter the mortality to experimental shock, although it did reduce the evidence of visceral congestion. 9 Evidence has been presented which tends to refute the idea that the protein ferritin (proposed as a vasomotor depressor substance derived from the liver) may be of significance in the development of "irreversible" shock. tO The injection of ferritin into hepatectomized-nephrectomized dogs failed to lower the blood pressure which was well above the shock level for a period of four hours or longer following ferritin injection. Other arguments against its being of etiologic significance in irreversible shock are advanced in this report. Liver and Hypertension
Recent experimentsll have shown that renal hypertension persists in the rabbit after hepatectomy or abdominal evisceration. Refractoriness to renin injections is produced more readily in these animals than in normal ones, which finding is consistent with the view that renin substrate, angiotonin, originates in the liver. However, the persistence of hypertension after refractoriness to renin has developed in the liverless rabbit indicates that renal hypertension is not dependent on a substrate derived from the liver. A reduced response to angiotonin by the liverless animal was noted, while adrenaline still produced a good response. Refractoriness of hepatectomized dogs to vasomotor active substances including epinephrine has also been reported. These animals were partially refractory to angiotonin and showed an increased susceptibility to tetraethylammonium. Shock was not excluded as a partial explanation for these results. 12 Anoxia
Hepatic anoxia may be a significant factor in contributing to the mortality or irreversibility of shock. This is evidenced by the increased survival of shocked animals when arterial blood is shunted into the portal system. 13 There is other evidence that acute hepatic anoxia is poorly tolerated in the dog in the absence of visceral congestion. One study,14 involving the production of ischemia of the liver and intestine, demonstrated that occlusion of the mesenteric artery and hepatic vessels for fifteen minutes or longer was usually fatal for dogs maintained on liberal doses of antibiotics pre- and postoperatively. Another study,15 in which hepatic ischemia was produced by vascular occlusion after portacaval anastomosis, gave results which indicated that to deprive the liver simultaneously of blood flowing through the portal vein, hepatic and gastroduodenal arteries for thirty minutes were generally fatal to a dog despite the liberal use of antibiotics.
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Infection and Blood Supply
Loss of the arterial blood supply to the liver per se can no longer be regarded as generally fatal. 16 It has been shown in several experimental studies that the hepatic and gastroduodenal arteries may be permanently ligated in the dog without causing death if anaerobic infection in the liver is prevented by pre- and postoperative administration of antibiotics (penicillin, streptomycin, aureomycin) that are effective against the anaerobic organisms 17 which frequently gain access to the liver by way of the portal blood supply. Previously, it had been thought that loss of the arterial blood supply to the liver produced some metabolic failure which the organism could not survive. It is now apparent from both clinical and experimental observations that the liver may tolerate loss of much of the arterial blood supply without gross evidence of functional abnormality, provided infection be excluded. That infection of the liver may be an important factor in some instances of "irreversible" shock is suggested by the striking reduction in mortality to hemorrhagic shock that has been produced by pretreatment of the experimental animals with aureomycin. 18 Contamination of the liver with bacteria from the intestinal tract must occur repeatedly in the healthy organism. 'I'he difficulty of securing a sample of sterile liver has long been recognized by investigators. Cultures of livers from healthy and shocked dogs indicated a high incidence of contamination in both groups-particularly in the shocked animals. 18 The organisms found are normal inhabitants of the intestinal canal, Clostridia being the predominant anaerobic organism. Hepatic Coma
The clinical impression19 that aureomycin may be of benefit to some patients in "hepatic coma" suggests that hepatic infection derived from the intestinal flora may be superimposed upon involvements of the liver that impair its circulation or reduce the viability of the liver cell in some other manner .20 That this reasoning may even be applicable to conditions that are known to be primarily nutritional in origin is suggested by the finding that the hepatic necrosis produced in the rat by a methioninedeficient diet was almost entirely eliminated by adding aureomycin to the diet. 21 An experimental condition which resembles "hepatic coma" has been produced by an extensive gradual reduction in the blood supply to the liver of dogs despite the use of antibiotics. 22 These animals lose their appetites and may develop muscular twitching, rigidity, fibrillations, convulsions, period of coma, jaundice, bradycardia, fever and neurological manifestations.
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Cirrhosis
Simultaneously, and in the wake of recognition of the fact that ligation of the hepatic artery may be tolerated in the experimental preparation, has come the use of this procedure to reduce portal pressure and combat the development of ascites in patients with cirrhosis of the liver. 23 l'he fact that the blood supply to the liver, as well as its parenchyma, has already been greatly reduced by the cirrhosis should not be disregarded. The evaluation of hepatic function is too incomplete and unsatisfactory to enable one to judge to what extent the further reduction in hepatic blood flow in cirrhosis may be compatible with the maintenance of adequate function. It is well established that there is normally a great reserve of hepatic tissue, but the cirrhotic liver not only has lost substance and circulation, but the remaining tissue is probably reduced in efficiency by virtue of the disorganization of the liver lobule in relation to its blood supply.24 Ascites
l'he origin of ascitic fluid has long been a debated subject. The common impression that it is derived as a transudate from the mesenteric vessels is at variance with some experimental studies on this question. It has been demonstrated experimentally that the following statements are true for the dog: (1) Complete ligation of the portal vein does not give rise to ascites in the normal dog, but may in the hypoproteinemic anima1. 25 (2) Constriction of the vena cava proximal to the liver will cause free fluid to accumulate in the peritoneal cavity of the dog. 26 (3) The flow of the hepatic lymph is greatly accelerated by constriction of the vena cava above the liver or by production of cirrhosis by the administration of carbon tetrachloride to the dog. 27 In unreported experiments,28 it was demonstrated that transferring the liver to a site above the diaphragm a few weeks prior to the experimental production of ascites (by constriction of the vena cava or carbon tetrachloride administration) resulted in the major accumulation of "ascitic" fluid occurring above the diaphragm. This finding suggests that the fluid was hepatic rather than mesenteric in origin. METABOLISM
The liver and kidneys largely control the environment of the cell since the function of these two organs determines the constancy of composition of the extracellular fluids. The liver is largely concerned with stabilizing the organic constituents of the extracellular fluids that are required in the nutrition of the cell. Through storage, synthesis, conjugation, excretion and the liberation of organic constituents, the liver stabilizes the
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media in which the cells of the body function. Stabilization of the concentration of blood sugar as well as the removal and addition of amino acids to the circulation are well known illustrations of hepatic functions by which the nutrition of the cell is stabilized. The conservation of nitrogen by transamination and amino acid synthesis also occur in this organ. The liver plays a fundamental role in the utilization of 2-carbon fragments in the formation of complex molecules such as bile acids and cholesterol. The autoregulatory mechanisms by which the constancy of the internal environment is maintained are presided over by nervous and hormonal factors which regulate the metabolic activity of hepatic cells. Part of this autoregulatory mechanism appears to include the activation and inactivation of certain hormones by the liver. The ability of the liver to inactivate one hormone may be influenced by the action of another hormone on the liver. For example, recent evidence indicates that liver .slices can inactivate the antidiuretic hormone of the posterior pituitary gland and that this ability is influenced by the adrenal gland. 3t HORMONES AND HEPATIC FUNCTION
Estrogens
Hormone inactivation by the liver has been most convincingly demonstrated for estrogens. Clinical and laboratory evidence of disturbed hormonal balance in patients with extensive liver disease has beell reported repeatedly.29 Gynecomastia, cutaneous spider nevi, testicular atrophy and loss of libido in male patients with chronic liver disease were found to be associated with a high urinary excretion of estrogen and a low output of neutral 17-ketosteroids and gonadotropins. However, some of the gynecomastia associated with liver disease may be nutritional in origin. 30 Thyroxine
Evidence that the liver plays a role in the metabolism and excretion of thyroxine has been summarized elsewhere. 32 Recent studies with radioactive I-thyroxine support the earlier impression that injected thyroxine is largely excreted in bile by the rat. Thyroxine is excreted as such and in the form of degradation products that have been only partially identified. 33 The distribution of 1131 in the liver and gastrointestinal tract of rats following the administration of physiologic amounts of tagged thyroxine has led to the suggestion that thyroxine may undergo an enterohepatic circulation. This study also demonstrates that the main avenue of excretion of 1131 given as thyroxine to the rat is the liver and intestinal tract. 34
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Epinephrine
The mode of action of other hormonal effects on the liver has been clarified. The hyperglycemic-glycogenolytic effects of epinephrine and the hyperglycemic factor of the pancreas have been shown to be due to their action on the phosphorylase activity of liver tissue. The activity of this enzyme is the limiting factor in the series of reactions necessary to convert glycogen into glucose. The evidence indicates that these and other glycogenolytic substances act on an enzyme system which keeps a balance between active and inactive forms of phosphorylase in the liver. The glycogenolytic agents were shown to increase phosphorylase activity both in vitro and in vivo. The in vitro effect on phosphorylase activity paralleled their hyperglycemic effects in ViVO. 35 The hyperglycemia characteristic of early stages of fever has been ascribed to sympathico-adrenal stimulation. Studies on liver slices from rabbits given typhoid-paratyphoid vaccine demonstrated increased glycogenolysis in liver slice preparations. 36 It would be interesting to know the relative phosphorylase activity of liver tissue from normal and febrile hyperglycemic animals. Insulin
The storage of glucose by the liver is one of its most clearly defined functions. This function is impaired in the uncontrolled diabetic as evidenced by a low hepatic glycogen content in the presence of excessively high concentrations of blood sugar. There is a difference of opinion among investigators as to whether or not this deficit in glycogen storage in the diabetic is associated with an excess liberation of glucose from the liver or largely due to an impaired peripheral utilization of sugar. Recent evidence 4 obtained by comparison of systemic arterial and hepatic vein blood showed that the fasting normal subject as well as the fasting hyperglycemic diabetic liberated approximately 100 to 125 mg. of glucose per minute from the liver. There was no definite excess liberation of glucose by the liver in the absence of insulin under the circumstances of these observations. Similar results hSlve been reported on diabetic dogs. 37 Estimation of hepatic blood flow in these experiments was based upon the removal of bromsulphthalein from the circulation. The reduction in hepatic glucose liberation which insulin produced in the normal subject and which was accompanied by hypoglycemia was followed by increased hepatic glucose output in association with increased blood flow through the liver. These effects were ascribed to stimulation of epinephrine release secondary to hypoglyecmia. Insulin injected into diabetic patients reduced the glucose liberated by the liver but failed to alter the hepatic blood flow, presumably because no hypoglycemia was produced and epinephrine release did not occur. Recent chemical evidence38 indicates
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that insulin hypoglycemia is associated with a marked reduction in the epinephrine content of the blood. Studies of liver slices from diabetic animals 39 have shown that insulin increases the conversion of lactic acid and other precursors of 2-carbon fragments into fat. These findings are in accord with other observations indicating that one of the effects of insulin is to promote the storage of glucose as fat as well as glycogen. 4o Apparently, both types of carbohydrate storage depend upon an effect of insulin on the liver celL It has long been known41 that the hepatectomized animal is relatively refractory to insulin. Increased and decreased requirements for insulin have been observed in diabetic patients who developed fatty infiltration of the liver. Experimentally, it has been shown that the insulin requirement of adult dogs with a stabilized alloxan diabetes is increased by reducing the blood flow to the liver. 42 This is further evidence that the effectiveness of insulin is partially dependent upon hepatic function. That insulin increases the peripheral oxidation of glucose seems equally well established. 43 ACTH and Cortisone
Adrenal cortical extract causes a deposition of glycogen in the liver of adrenalectomized animals. This fact is the basis for the bioassay of adrenal cortical hormones. Compounds E and F have a similar effect. It has likewise been demonstrated that these compounds promote the deamination of amino acids, presumably by the liver, thereby increasing the formation of carbohydrate and fat from ingested protein. This increased catabolism or decreased anabolism of protein is responsible for the negative nitrogen balance associated with various stresses or with excessive adrenal cortical hormone administration. 44 This action by the adrenal corticoids is antagonistic to the anabolic effect of insulin which appears to be exerted peripherally as well as on the liver. 45 The fact that ketone body formation by the liver may be influenced by cortisone administration is additional evidence of an adrenal cortical effect on the degradation and interconversion of foodstuffs by the liver. 46 • 47 These effects may include the formation of carbohydrate from fat. 48 Clinical reports concerning the effect of ACTH and cortisone on hepatic disease are varied and conflicting. Biopsy evidence of reduced inflammation and fat infiltration was reported in 2 to 4 patients with cirrhosis who received ACTH for ten to fifteen days. There was also evidence of increased hematopoiesis and a greater appetite in all 4 patients. 49 Marked symptomatic improvement associated with a decreased serum bilirubin occurred in 5 patients with acute viral hepatitis treated with ACTH for nine to twenty-one days.60 Definite evidence of improvement, both laboratory and clinical, has
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been obtained in 1 patient with sarcoidosis of the liver treated with ACTH or cortisone for the past two years. Discontinuation of hormone administration on two occasions has led to a rapid return of the clinical manifestations of the disease. 51 The majority of investigators have found little or no laboratory evidence of permanent improvement in patients with cirrhosis given adrenal hormones, although temporary relief from pruritus associated with a reduction in the elevated blood bile salts was observed. 52 Serious complications due to hormone therapy have developed in some patients. Metabolic studies on patients with hepatic disease indicate that in general they excrete less than normal amounts of 17-ketosteroids in the urine. 53 , 54 'fhe administration of ACTH caused a definite increase in the urinary excretion of 17-ketosteroids and a proportionately greater rise in corticoid excretion in patients with cirrhosis. However, a smaller portion of excreted steroids was conjugated as glucuronidates than occurs normally. ACTH also appeared to produce a fasting hyperglycemia more readily in patients with advanced liver disease. 54 It was suggested that this could be due to a reduced capacity of the liver to store glycogen. Attention has been called to a group of young females with advanced cirrhosis of the liver whose clinical manifestations are suggestive of hyperadrenalism. These patients' manifestations included hirsutism, pigmented abdominal striae, obesity, acne, amenorrhea and "moon facies." Their urinary corticoid excretion was unusually high. 55 'rhese features appeared concomittantly with the onset of jaundice and did not appear to be a consequence of longstanding hepatic insufficiency. The most striking laboratory characteristic of this group was a marked elevation of the globulin fraction of the serum to values as high as 10 gm. per 100 cc.
AMINO ACIDS AND HEPATIC FUNCTION
It is reasonable to suppose that the increased urinary excretion of amino acids by the uncontrolled diabetic is, at least, partially due to a lack of the normal anabolic effect of insulin on the liver. 56 A marked increase in the urinary loss of amino acids also occurs following removal of the liver 57 and frequently occurs in liver disease. 58 Following hepatectomy, the increased excretion affects all of the amino acids except glycine, while in the diabetic animal the increase in glycine excretion is quite striking and may be due to excessive synthesis of this amino acid by the liver. CHOLESTEROL METABOLISM
It is generally recognized that the plasma concentration of cholesterol and the extent of ester forma.tion are normally regulated by the liver.
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It has been demonstrated that liver slices can synthesize cholesterol from acetic acid and other 2-carbon fragments 59-also that fat can be degraded to aceta-acetate and then converted into cholesterol without first being converted to acetate. 60 Factors that influence cholesterol synthesis by the liver are poorly defined although it has been demonstrated that fasting and caloric restriction reduce the synthesis of cholesterol from acetate by liver slices. 61 It has been proposed 62 that the increased cholesterol content of bile shown to result from thyroxine administration to the rat was due to increased synthesis of this substance by the hepatic cell. These same authors present evidence 63 that the cholesterol content of bile is independent of the cholesterol content of body fluids, but is related to the extent of cholesterol synthesis by the liver. The liver has likewise been shown to be the principal site of synthesis of plasma phospholipids. The ratio of cholesterol to lecithin in plasma is thought to be a factor in the tendency for cholesterol deposition to occur in the tissues. A relatively high lecithin content is believed to be a factor in stabilizing plasma cholesterol and presenting its deposition. Particle size is recognized as a factor in cholesterol.-lePQiit1,Qp,64 Qlldt·~rio$ ratios of cholesterol to lecithin may be expected to give rise to different degrees of dispersion of the lyophobic substance, cholesterol. The serum phospholipid and cholesterol values are normally related and disease of the liver is frequently associated with alterations in the cholesterolphospholipid ratio. 65 Experimental alterations in this ratio have likewise been produced by injury to the liver. 66 It has also been shown that the body can destroy cholestero1. 67 Experimental studies indicate that impairment of hepatic function reduces the ability of the dog to destroy cholesterol from exogenous sources and results in its accumulation in the plasma and liver. 66 Clinically, the instances in which hypercholesterolemia represents an inability on the part of the liver to destroy cholesterol remain unrecognized. Evidence is accumulating which suggests that a good many instances of hypercholesterolemia are at least partially due to exogenous cholesterol since dietary restriction of fat and cholesterol reduces the plasma concentration of the latter substance. This fact, taken with evidence of cholesterol destruction by the liver, would suggest that these patients have impairment in the liver's ability to destroy cholesterol, or else that they have an unusual absorption from the intestinal tract. Other experimental studies 68 suggest that another product of hepatic synthesis, cholic acid, may be a factor in producing hypercholesterolemia. It has been demonstrated in the rat that elevating the cholic acid content of the blood by obstruction of the common bile duct or cholate infusion will rapidly elevate the cholesterol content of the blood stream. Relief of obstruction of the common bile duct results in a decrease in plasma cholesterol without an increased excretion in the bile. The increased plasma cholesterol secondary to
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common bile duct obstruction has been established as hepatic in ori•
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gmThe lipemia induced in the fowl by stilbesterol administration has
been shown to be dependent on hepatic function. 70 Estrogens have also been shown to influence the plasma lipoprotein and cholesterol content of human subjects with atherosclerosis.71 It seems probable that the temporary reduction in plasma cholesterol induced by estrogen administration may have been mediated by the liver. LABORATORY TESTS PERTAINING TO HEPATIC FUNCTION
Serum Alkaline Phosphatase The' origjn and significance of the serum phosphatase elevation in liver disease has been the subject of debate for a number of years. Some authors believe the serum increase to arise from"a failure of excretion by the liver of alkaline phosphatase that originate~ in the skeleton. Others believe that the major portion of the increase in serum alkaline phosphatase in hepatic disease results from regurgitation of the enzyme from the hepatic cell where it is formed and from which it is normally excreted in the bile. The concept one entertains may have some influence on the interpretation of clinical data and is therefore important from a practical as well as an academic point of view. Patients with acute extensive parenchymatous failure of the liver have stools poor in pigment, marked elevation of the serum bilirubin and only a relatively slight elevation of the alkaline phosphatase. If both bilirubin and phosphatase were similarly extrahepatic in origin, there should be a parallelism in their increase, since failure of excretion for both would occur. However, in such instances the concentration of serum bilirubin mounts rapidly as in an extrahepatic common bile duct obstruction, but the phosphatase values do not increase much and tend to level off while the bilirubin values continue to rise for some time. At the same time other signs of failure of the hepatic parenchyma occur, such as a reduction of cholesterol esters and urea content of blood. Recent experiments72 tend to confirm the hepatic origin of the serum phosphatase increase in liver disease. According to these results obstruction of the common bile duct of the dog causes a much greater rise in serum phosphatase during the subsequent twenth-four hours than occurs in the twenty-four hours following hepatectomy. In both instances there is a similar loss of excretory function but the liver is excluded as a source of enzyme in the hepatectomized animal. From these experiments it is also apparent that the diet prior to obstruction of the common bile duct influences the rate of enzyme increase in the serum following obstruction. These experiments are in direct contradictjon to the results of others that have been~reported previously. Recognition of 3. dissociation between the bilirubin and phosphatase
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increase in liver disease is important for the clinician. rfhe patient with a high serum bilirubin due to an excretory failure by the liver, who has at the same time a low serum alkaline phosphatase, may be expected to have extensive parenchymatous liver failure and is invariably a poor surgical risk. Such a circumstance is usually not mechanical in origin, or if it is, the defect is of long standing. Biopsy
Several studies have appeared recently in which biopsy material has been compared to the results of a battery of liver function tests. rfhese studies reveal that morphological evidence of liver damage may exist in the presence of normal liver function tests in some patients, while abnormal liver function tests may be obtained in instances where biopsy material appears to be perfectly normal morphologically.73 l"'hese considerations make it evident that both procedures may he essential to accurate diagnostic studies. Serum Choline Esterase and Other Tests
A comparison of the serum' choline esterase activity with ten other commonly employed liver function tests indicated it to be a valuable aid in following the progress of patients with acute hepatitis. Initially the serum choline esterase activity was depressed in all patients and the value rose as evidence of hepatocellular damage subsided. 74 However, the serum choline esterase activity does not always reflect a relapse in acute hepatitis and is usually norma] in chronic viral hepatitis. rfhe wide normal variation and overlap in a variety of diseases limits its usefulness as a practical test of liver function. 75 C~ompari.son of biopsy findings with a battery of liver function tests indicated that in patients with portal cirrhosis the best correlation was between the biopsy and bromsulphthalein excretion. In diagnosed cases of recurrent hepatitis the biopsy might appear normal while the function tests, particularly the thymol turbidity test, would be abnorma1. 76 A study of histologically proven cases of liver disease indicated that focal lesions usually did not alter parenchymal function significantly. The tests most frequently positive in focal condition were the alkaline serum phosphatase, total serum cholesterol and prompt reacting bilirubin. Bromsulphthalein was recommended as the best single screening test although admittedly not infallible.77 A comparison of electrophoretic patterns in patients with portal and biliary cirrhosis usually shows clear-cut differences since there is generally a steep fj-globulin peak in the latter condition. (jenerally, portal cirrhosis is characterized by serum cholesterol values that are less than normal while they are usually elevated in biliary eirrhosis. 78
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An attempt to use the glycemic response to epinephrine as a measure of hepatic glycogen gave rise to a wide variety of results. A seasonal difference in the glycemic response of an individual to epinephrine was demonstrated. A greater response occurred from October to May than from June to September. Two successive tests four days apart always gave a lower value on the second test. 79 Urobilinogen disappeared from the stools of normal subjects receiving 2 gm. of aureomycin daily. The bilirubin content of the stools increased and a small amount of urobilinogen persisted in the urine. The use of aureomycin could complicate the differential diagnosis of jaundice. 80 REFERENCES 1. Knisely, M. H., Bloch, E. H. and Warner, L.: Selective Phagocytosis 1. Microscopic Observations Concerning the Regulation of Blood Flow through the Liver and Other Organs and the Mechanism and Rate of Phagocytic Removal of Particles from the Blood: Det Kongelige Danske Videnskabernes Selskab, Biologiske Skrifter, Bind. IV, Nr. 7. KS?Sbenhavn, I Kommission Hos Ejnar Munksgaard, 1948. 2. Daniel, P. M. and Prichard, M. M. L.: Variations in the Circulation of the Portal Venous Blood within the Liver. J. Physiol. 114-: 521, 1951. 3. Maegraith, B. G.: Micro-Anatomy of the Hepatic Vascular System. In Liver Injury, p. 181, ed. by F. W. Hoffbauer, Josiah Macy, Jr. Foundation, New York, 1951. 4. a. Sherlock, S.: Hepatic Vein Catheterisation in Clinical Research. Proc. Inst. Med. Chicago 18: 335, 1951. b. Sherlock, S., Bearn, A. G. and Billing, B.: The Effect of Insulin on the Liver in Normal and Diabetic Man. In Liver Injury, p. 205, ed. by J1~. W. Hoffbauer, Josiah Macy, Jr. Foundation, New York, 1951. 5. Daniel, P. M. and Prichard, M. M. L.: Effects of Stimulation of the Hepatic Nerves and of Adrenaline upon the Circulation of the Portal Venous Blood within the Liver. J. Physiol. 114-: 538, 1951. 6. Deysach, L. J.: The Nature and Location of the "Sphincter Mechanisnl" in the Liver as Determined by Drug Actions and Vascular Injections. Am. J. Physiol. 132: 713,1941. 7. Thomas, W. D. and Essex, H. E.: Observations on the Hepatic Venous Circulation with. Special Reference to the Sphincteric Mechanism. Am. J. Physiol. 168: 303, 1949. 8. Frank, H. A., Seligman, A. M. and Fine, J.: Traumatic Shock. XIII. The Prevention of Irreversibility in Hemorrhagic Shock by Vive-Perfusion of the Liver. J. Clin. Investigation 25: 22, 1946. 9. Frank, H. A., Glotzer, P., Jacob, S. W. and Fine, J.: Hemorrhagic Shock in Eck Fistula Dogs. Am. J. Physiol. 167: 508, 1951. 10. Frank, H. A. and others: Traumatic Shock. XXII. Irreversibility of Hemorrhagic Shock and VDM Hypothesis. Am. J. Physiol168: 150, 1952. 11. Drury, D. R. and others: Renin Substrate and Renal Hypertension, Including a One-Stage Method for Eviscerating in the Rabbit. Am. J. Physiol. 164-: 630, 1951. 12. Page, I. H.: Influence of the-"Liver on Vascular Reactivity. Am. J. Physiol. 160: 421, 1950. 13. Cohn, R. and Parsons, H.: Relationship of Portal Hypertension and Irreversibility of Shock. Am. J. Physiol. 160: 437, 1950. 14. Raffucci, F. L. and Wangensteen, O. H.: Tolerance of Dogs to Occlusion of Entire Afferent Vascular Inflow to the Liver. "Surgical Forum" , American College of Surgeons. Philadelphia, W. B. Saunders Co., 1951.
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15. Hines, J. R. and Freeman, S.: Acute Hepatic Ischemia. Unpublished data. 16. R. Markowitz, J., Rappaport, A. and Scott, A. C.: Prevention of Liver Necrosis following Ligation of Hepatic Artery. Proc. Soc. Exper. BioI. & Med. 70: 305, 1949. b. Markowitz, J., Rappaport, A. and Scott, A. C.: The Function of the Hepatic Artery in the Dog. Am. J. Digest. Dis. 16: 344, 1949. 17. Tanturi, C., Swigart, L. L. and Campa, J. F.: Prevention of Death from Experimental Ligation of the Liver (Hepatic Proper) Branches of the Hepatic Artery. Surg., Gynec. & Obsta 91: 680, 1950. 18. Frank, H. A. and others: Traumatic Shock. XXI. Effectiveness of an Antibiotic in Experimental Hemorrhagic Shock. Am. J. Physiol. 168: 430, 1952. 19. Farquhar, J. D. and others: Studies on the Use of Aureomycin in Hepatic Disease. Ill. A Note on Aureomycin Therapy in Hepatic Coma. Am. J. M. Se. 220: 166, 1950. 20. Shaffer, J. M. and others: Studies on the Use of Aureomycin in Hepatic Disease. IV. Aureomycin Therapy in Chronic Liver Disease. Am. J. M. Sci., 220: 173, 1950. 21. Gyorgy, P. and others: Studies on the Use of Aureomycin in Hepatic Disease. 11. Effect of Aureomycin on Experimental Dietary Hepatic Necrosis. Am. J. M. Se. 220: 6, 1950. 22. a. Rappaport, A. M.: Experimental Ischemia of the Liver and Hepatic Coma. In Liver Injury, p. 146, ed. by F. W. Hoffbauer, Josiah Maey, Jr. Foundation, New York, 1951. b. Rappaport, A. M. and Lotto, W. N.: Experimental Hepatic Coma. Proc. Soc. Exper. BioI. & Med. 78: 14, 1951. 23. Reinhoff, W. F., Jr.: Ligation of the Hepatic and Splenic Arteries in the Treatment of Portal Hypertension with a Report of Six Cases. Johns Hopkins Hosp. Bull. 88: 368, 1951. 24. a. Kelty, R. H., Baggenstoss, A. H. and Butt, H. R.: The Relation of the Regenerated Hepatic Nodule to the Vascular Bed in Cirrhosis. Proc. Staff Meet., Mayo Clinic 25: 17, 1950. b. Daniel, P. M., Prichard, M. M. L. and Reynell, P. C.: The Portal Circulation in Experimental Cirrhosis of the Liver. J. Path. & Bact. 64: 53,1952. 25. Volwiler, W., Bollman, J. L. and Grindlay, J. H.: A Comparison of Two Types of Experimental Ascites. Proc. Staff Meet., Mayo Clinic 26: 31, 1950. 26. Bolton, C.: The Pathological Changes in the Liver Resulting from Passive Venous Congestion Experimentally Produced. J. Path. & Bact. 19: 258, 1914. 27. Nix, J. T., Flock, E. V. and Bollman, J. L.: Influence of Cirrhosis on Proteins of Cisternal Lymph. Am. J. Physiol. 164: 117, 1951. 28. Ivy, J. H. and Freeman, S.: Unpublished results on the origin of ascitic fluid produced experimentally in the dog. 29. Dohan, F. C. and others: Hormone Excretion in Liver Disease. J. Clin. Investigation 31: 481, 1952. 30. Kark, R. M., Morey, G. R. and Paynter, C. R.: Refeeding (Nutritional) Gynecomastia in Cirrhosis of the Liver. I. Clinical Observations. Am. J. M. Se. 220: 154, 1950. 31. Gaunt, R.: Adrenal Cortical Hormone and Related Hormones in Water Metabolism in Renal Function, p. 10, ed. by S. E. Bradley, Josiah Macy, Jr. Foundation, N. Y., 1950. 32. Monroe, R. A. and Turner, C. W·.: The Metabolism of Thyroxine. Missouri Agr. Exp. Sta., Res. Bull. 446, 1949. 33. Taurog, A., Briggs, F. N. and Chaikoff, I. L.: IU1-Labelled L-Thyroxine. I. An Unidentified1Excretion Product in Bile. J. BioI. Chem. 191: 29, 1951. 34. Johnson, H. W. and lAlbert, A.: The Excretion and Distribution of 1131 folfowingAdministration of Physiologic Amounts of Labeled Iodide, Diiodotyrosine and Thyroxine in the Rat. Endocrinology 48: 669, 1951. 35. Sutherland, E. W. and Cori, C. F.: Effect by Hyperglycemic-Glyco~enolytic
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Factor and Epinephrine on Liver Phosphorylase. J. BioI. Chem. 188: 531, 1951. 36. Fishgold, J. T., Grant, R., Field, J. and Hall, V. E.: Oxygen Consumption and Glucose Exchange in Vitro of Liver Slices from Febrile Rabbits. Am. J. PhysioI. 166: 113, 1951. 37. Crandal1: L. A., Jr. and Lipscomb, A.: A Direct Measurement of Hepatic Glucose Production in Experimental Diabetes Mellitus. Am. J. Physiol. 148: 312, 1947. 38. Weil-Malherbe, H. and Bone, A. D.: The Chemical Estimation of AdrenalineLike Substances in Blood,- Biochem. J. 51: 311, 1952. 39. a. Felts, J. M., Chaikoff, I. L. and Osborn, M. J.: Insulin and the Fate of Acetate and Formate in the Diabetic Liver. J. BioI. Chem. 193: 557,1951. b. Felts, J. M., Chaikoff, I. L. and Osborn, M. J.: Insulin and the Fate of Pyruvate in the Diabetic Liver. J.BioI. Chem. 193: 549, 1951. 40. a. Chernick, S. S. and others: Lipogenesis and Glucose Oxidation in the Liver of t.he Alloxan-Diabetic Rat. J. BioI. Chem. 186: 527,1950. Chernick, S. S. and Chaikoff, 1. L.: Insulin and Hepatic Utilization of Glucose for Lipogenesis. J. BioI. Chem. 186: 535, 1950. b. Stetten, D., Jr. and Boxer, G. E.: Studies in Carbohydrate Metabolism. Ill. Metabolic Defects in Alloxan Diabetes. J. BioI. Chem. 156: 271,1944. 41. Markowitz, J., Mann, F. C. and Bollman, J. L.: The Glycogenic Function of Skeletal Muscle in the Dehepatized Dog, with Special Reference to the Role of Insulin Therein. Am. J. PhysioI. 87: 566, 1929. 42. Koide, S. and Freeman, S.: Effect of Eck-Fistula Formation on Alloxan Diabetic Dogs. Am. J. Physiol. 167: 193, 1951. 43. Wick, A. N. and others: Action of Insulin on the Extra-Hepatic Tissues. J. BioI. Chem. 188: 241, 1951. 44. Hoberman, H. D.: Endocrine Regulation of Amino Acid and Protein Metabolism During Fasting. Yale J. BioI. & Med. 22: 341, 1949-50. 45. Russell, J. A. and Cappiello, M.: The Relationship of Temperature and Insulin Dosage to the Rise in Plasma Amino Nitrogen in the Eviscerated Rat. Endocrinology 44: 127, 1949. 46. Tepperman, J. and DeWitt, J. M.: Effects of Pitui'tary Growth Hormone and Cortisone Administration in Vivo on Ketogenesis by Surviving Liver Slices Obtained from Hypophysectomized Rats. Fed. Proc. 10: 136, 1951. 47. Kinsell, L. W. and others: Hormonal Regulation of Fat Metabolism. 1. Effects of ACTH and of Certain Steroid Hormones upon Fasting-Induced Hyperketonemia. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., Vo!. I, p. 308. 48. Segaloff, A. and Many, A. S.: The Effect of ACTH on Glucose and Ketone Production in Phloridzinized Rats. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., VoI. 1., p. 301. 49. Brown, H., Jager, B. V. and Tyler, F. H.: ACTH in Cirrhosis of the Liver. Am. J. Med. 10: 770, 1951. 50. Colbert, J. W. and others: The Use of ACTH in Acute Viral Hepatitis. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., Vo!. I, p.371. 51. Foxworthy, D. T. and Freeman, S.: Unpublished data. Hines Hospital for Veterans, Hines, Illinois. 52. Williams, C. F. and Flink, E. B.: Corticotropin Therapy of Chronic Liver Disease. J. Lab. & Clin. Med. 39: 888, 1952. 53. Butt, H. R. and others: Observations on the Effect of Cortisone Acetate on Two·Patients with Hepatic Disease. J. Lab. & Clin. Med. 37: 870,1951. 54. Bongiovanni, A. M. and Eisenmenger, W. J.: Observations During the Administration of ACTH to Patients with Chronic Liver Disease. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., Vol. I, p.390. 55. Bongiovanni, A. M. and Eisenmenger, W. J.: Adrenal Cortical Metabolism in Chronic Liver Disease. J. Clin. Endocrinol. 11: 152, 1951.
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56. Ivy, J. H., Svec, M. and Freeman, S.: Free Plasma Level and Urinary :Excretion of Eighteen Amino Acids in Normal and Diabetic Dogs. Am. tT. Physiol. 167: 182, 1951. 57. Freeman, S. and Svec, M.: Effect of Complete Hepatectomy upon Plasma Concentration and Urinary Excretion of Eighteen Amino Acids. Am. tJ. Physiol. 167: 201, 1951. 58. Dunn, M. S. and others: Urinary Excretion of Amino Acids in Liver Disease. J. Clin. Investigation 29: 302, 1950. 59. Bloch, K., Borek, E. and Rittenberg, D.: Synthesis of Cholesterol in Surviving Liver. J. BioI. Chem. 162: 441, 1946. 60. Curran, G. L.: Utilization of Acetoacetic Acid in Cholesterol Synthesis by Surviving Rat Liver. J. BioI. Chem. 191: 775, 1951. 61. Tomkins, G. M. and Chaikoff, 1. L.: Cholesterol Synthesis by Liver.!. Influence of Fasting and of Diet. J. BioI. Chem. 196: 569, 1952. 62. Byers, S. O. and Friedman, M.: Production and Excretion of Cholesterol in Mammals. VII. Biliary Cholesterol: Increment and Indicator of Hepatic Synthesis of Cholesterol. Am. J. Physiol. 168: 297, 1952. 63. Byers, S. O. and Friedman, M.: Observations Concerning the Production and Excretion of Cholesterol in Mammals. J. Exper. Med. 95: 19, 1952. 64. Gofman, J. W. and others: Blood Lipids and Human Atherosclerosis. Circulation 2: 161, 1950. 65. Albrink, M. J., Man, E. B. and Peters, J. P.: Serum Lipids in Infectious Hepatitis and Obstructive Jaundice. J. Clin. Investigation 29: 781, 1950. 66. Bailey, R. O. and Freeman, S.: Hepatic Function and Cholesterol Tolerance in the Dog. J. Lab. & Clin. Med. 39: 184, 1952. 67. Gould, R. G.: The Comparative Metabolism of Dietary and Endogenous Cholesterol Differentiated by Use of Radioactive Carbon. Circulation 2: 467, 1950. 68. Byers, S. O. and Friedman, M.: Effect of Various Bile Acids on the Hypercholesteremia Following Biliary Obstruction in the Rat. Am. J .Physiol. 168: 138, 1952. 69. Bloom, W. L. and others: Glycogen Fractions of Liver and Muscle. J. BioI. Chem. 188: 631, 1951. 70. Ranney, R. E., Chaikoff, I. L. and Dobson, :E. L.: A Procedure for Functional Hepatectomy of the Unanesthetized Fowl. Am ..1. Physiol. 165: 588, 1951. 71. Barr, D. P.: The Influence of Estrogens on Lipoproteins in Atherosclerosis. 65th Annual Meeting of the American Association of Physicians, Atlantic City, N. J., May, 1952. 72. Freeman, S.: Comparison of Effects of Hepatectomy and of Common Bile Duct Obstruction on Serum Phosphatase of Adult Dogs. Am. J. Physiol. 164-: 792, 1951. 73. Berk, J. E. and Shay, H.: Liver Biopsy and Liver Function Tests. J.A.M.A. 14-8: 109, 1952. 74. Vorhaus, L. J., Scudamore, H. H. and Kark, R. M.: Measurement of Serun1 Cholinesterase Activity: A Useful Test in the Management of Acute Hepatitis. Am. J. M. Se. 221: 140, 1951. 75. Mann, J. D., Mandel, W. I. and Knowlton, M. A.: Serum Cholinesterase Activity in Liver Disease. J. Lab. & Clin. Med. 39: 543, 1952. 76. Moyer, J. H. and Wurl, O. A.: Liver Biopsy: Correlation with Clinical and Biochemical Observations. Am. J. M. Se. 221: 28, 1951. 77. Ricketts,W. E.: Pathological Liver with Minimal or No Change in "Liver Tests." Am. J. M. Se. 221:.287, 1951 78. Ricketts, W. E. and Sterling, K.: Comparative Studies of "Liver Tests" and Electrophoretic Analyses of Serum Proteins in Portal and Biliary Cirrhosis. Am. J. M. Se. 221: 38, 1951. 79. Altschule, M. D. and Sigel, E. P.: Inadequacy of the Glycemic Reaction to Epinephrine as a Measure of Hepatic Glycogen. Am. J. M. Se. 222: 50, 1951. 80. GaIt, J. and Hunter, R. B.: The Effect of Aureomycin on Certain Liver Function Tests and Blood Coagulation. Am. J. M. Se. 220: 508, 1950.
CIRCULATION
and biochemical aspects of hepatic function are extremely numerous and diversified. This relatively huge organ is strategically situated to exert both physical and chemical influence on the volume and composition of the circulating blood. Through its portal system must pass all of the blood from the intestines, spleen and a portion of the stomach. In addition to this large volume, low pressure system of blood poor in oxygen, the liver receives approximately one-fourth of its blood supply through the hepatic and gastroduodenal arteries. Within the sinusoids of the liver, blood may temporarily stagnate in certain areas while others manifest an active circulation. l In certain species, it seems probable that the intrahepatic circulation may be altered at times by a system of shunts that enables blood to pass from the portal vein to the inferior vena cava without passage through the sinusoids. 2 PHYSIOLOGICAL
Hormonal Effects It has been demonstrated 3 that the inflow, outflow and storage of blood in the perfused isolated liver is influenced by epinephrine and acetylcholine. The response of the liver to these stimuli will depend upon its state at the time of stimulation as well as on the strength of the stimulus. Increased blood flow through the splanchnic and portal vessels has been reported 4 to follow the administration of epinephrine and in association with the hypoglycemia that occurs approximately forty-five minutes after insulin injection. There are differences in the effects of epinephrine on blood flow through the liver as reported by various investigators. However, many of these experiments are not comFrom the Department of Biochemistry, Northwestern University Medical School, Chicago.
* Professor
of Biochernistry, Northwestern University Medical School. 109
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parable, as the experimental conditions, dosages and routes of administration differed. Evidence of increased rate of blood flow through the liver following epinephrine is compatible with a reduction of the reservoir of blood in the splanchnic system and liver. Shrinkage of these organs as well as acceleration of the mobilization and transportation of glucose are all parts of the organism's preparedness for flight or fight. Nervous Stimuli
The generous plexus of fibers from the sympathetic nervous system that surrounds the hepatic artery makes apparent a rich source of nervous stimuli that may alter the vasomotor tone of the hepatic circulation. Their stimulation reduced the vascular bed in the liver of several species as judged by the behavior of Diodrast injected through the portal system and caused intrahepatic vessels of the portal system to constrict. 5 This portal constriction was associated with a greater flow in the shorter pathways through the liver and would provide an alternate route to the final common pathway of arterial and venous blood which entails passage of blood though the sinusoids of the liver lobule.!' 2,3 Reservoir Function
The normal liver is capable of some expansion and contraction depending upon the extent of its engorgement with blood. Extrahepatic factors concerned in its circulation include the systemic circulation, the metabolic activity of this organ and the vasomotor tone of the splanchnic vessels; low pressures, large volume and a marked variability in tone characterize this vascular bed. Minor variations in intra-abdominal volume and pressure associated with normal respiratory movements contribute materially to the flow of blood in the portal system and through the liver. The temporary storage of blood is a normal function of the liver. It seems well established that a sphincter mechanism capable of trapping blood within the liver and splanchnic area exists in the hepatic veins of· the dog and other species. 5 , 6,7 There is no direct evidence that such a spincter mechanism exists in man. Secondary Surgical Shock
Studies have been made regarding the extent to which an exaggerated response by a sphincter mechanism may contribute to the findings and mortality in experimental shock due to controlled hemorrhage. Studies indicate that the maintenance 'of an' adequate portal circulation and oxygen supply to the liver enabled recovery from experimental shock to occur more frequently than was otherwise the case. 8 That the splanchnic engorgement and congestion of the gastrointestinal tract were not of primary significance in the irreversibility of shock was indicated by the
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findings that diverting blood to the vena cava through a portacaval anastomosis did not alter the mortality to experimental shock, although it did reduce the evidence of visceral congestion. 9 Evidence has been presented which tends to refute the idea that the protein ferritin (proposed as a vasomotor depressor substance derived from the liver) may be of significance in the development of "irreversible" shock. tO The injection of ferritin into hepatectomized-nephrectomized dogs failed to lower the blood pressure which was well above the shock level for a period of four hours or longer following ferritin injection. Other arguments against its being of etiologic significance in irreversible shock are advanced in this report. Liver and Hypertension
Recent experimentsll have shown that renal hypertension persists in the rabbit after hepatectomy or abdominal evisceration. Refractoriness to renin injections is produced more readily in these animals than in normal ones, which finding is consistent with the view that renin substrate, angiotonin, originates in the liver. However, the persistence of hypertension after refractoriness to renin has developed in the liverless rabbit indicates that renal hypertension is not dependent on a substrate derived from the liver. A reduced response to angiotonin by the liverless animal was noted, while adrenaline still produced a good response. Refractoriness of hepatectomized dogs to vasomotor active substances including epinephrine has also been reported. These animals were partially refractory to angiotonin and showed an increased susceptibility to tetraethylammonium. Shock was not excluded as a partial explanation for these results. 12 Anoxia
Hepatic anoxia may be a significant factor in contributing to the mortality or irreversibility of shock. This is evidenced by the increased survival of shocked animals when arterial blood is shunted into the portal system. 13 There is other evidence that acute hepatic anoxia is poorly tolerated in the dog in the absence of visceral congestion. One study,14 involving the production of ischemia of the liver and intestine, demonstrated that occlusion of the mesenteric artery and hepatic vessels for fifteen minutes or longer was usually fatal for dogs maintained on liberal doses of antibiotics pre- and postoperatively. Another study,15 in which hepatic ischemia was produced by vascular occlusion after portacaval anastomosis, gave results which indicated that to deprive the liver simultaneously of blood flowing through the portal vein, hepatic and gastroduodenal arteries for thirty minutes were generally fatal to a dog despite the liberal use of antibiotics.
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Infection and Blood Supply
Loss of the arterial blood supply to the liver per se can no longer be regarded as generally fatal. 16 It has been shown in several experimental studies that the hepatic and gastroduodenal arteries may be permanently ligated in the dog without causing death if anaerobic infection in the liver is prevented by pre- and postoperative administration of antibiotics (penicillin, streptomycin, aureomycin) that are effective against the anaerobic organisms 17 which frequently gain access to the liver by way of the portal blood supply. Previously, it had been thought that loss of the arterial blood supply to the liver produced some metabolic failure which the organism could not survive. It is now apparent from both clinical and experimental observations that the liver may tolerate loss of much of the arterial blood supply without gross evidence of functional abnormality, provided infection be excluded. That infection of the liver may be an important factor in some instances of "irreversible" shock is suggested by the striking reduction in mortality to hemorrhagic shock that has been produced by pretreatment of the experimental animals with aureomycin. 18 Contamination of the liver with bacteria from the intestinal tract must occur repeatedly in the healthy organism. 'I'he difficulty of securing a sample of sterile liver has long been recognized by investigators. Cultures of livers from healthy and shocked dogs indicated a high incidence of contamination in both groups-particularly in the shocked animals. 18 The organisms found are normal inhabitants of the intestinal canal, Clostridia being the predominant anaerobic organism. Hepatic Coma
The clinical impression19 that aureomycin may be of benefit to some patients in "hepatic coma" suggests that hepatic infection derived from the intestinal flora may be superimposed upon involvements of the liver that impair its circulation or reduce the viability of the liver cell in some other manner .20 That this reasoning may even be applicable to conditions that are known to be primarily nutritional in origin is suggested by the finding that the hepatic necrosis produced in the rat by a methioninedeficient diet was almost entirely eliminated by adding aureomycin to the diet. 21 An experimental condition which resembles "hepatic coma" has been produced by an extensive gradual reduction in the blood supply to the liver of dogs despite the use of antibiotics. 22 These animals lose their appetites and may develop muscular twitching, rigidity, fibrillations, convulsions, period of coma, jaundice, bradycardia, fever and neurological manifestations.
Physiology and Biochemistry of
I~iver
1.13
Cirrhosis
Simultaneously, and in the wake of recognition of the fact that ligation of the hepatic artery may be tolerated in the experimental preparation, has come the use of this procedure to reduce portal pressure and combat the development of ascites in patients with cirrhosis of the liver. 23 l'he fact that the blood supply to the liver, as well as its parenchyma, has already been greatly reduced by the cirrhosis should not be disregarded. The evaluation of hepatic function is too incomplete and unsatisfactory to enable one to judge to what extent the further reduction in hepatic blood flow in cirrhosis may be compatible with the maintenance of adequate function. It is well established that there is normally a great reserve of hepatic tissue, but the cirrhotic liver not only has lost substance and circulation, but the remaining tissue is probably reduced in efficiency by virtue of the disorganization of the liver lobule in relation to its blood supply.24 Ascites
l'he origin of ascitic fluid has long been a debated subject. The common impression that it is derived as a transudate from the mesenteric vessels is at variance with some experimental studies on this question. It has been demonstrated experimentally that the following statements are true for the dog: (1) Complete ligation of the portal vein does not give rise to ascites in the normal dog, but may in the hypoproteinemic anima1. 25 (2) Constriction of the vena cava proximal to the liver will cause free fluid to accumulate in the peritoneal cavity of the dog. 26 (3) The flow of the hepatic lymph is greatly accelerated by constriction of the vena cava above the liver or by production of cirrhosis by the administration of carbon tetrachloride to the dog. 27 In unreported experiments,28 it was demonstrated that transferring the liver to a site above the diaphragm a few weeks prior to the experimental production of ascites (by constriction of the vena cava or carbon tetrachloride administration) resulted in the major accumulation of "ascitic" fluid occurring above the diaphragm. This finding suggests that the fluid was hepatic rather than mesenteric in origin. METABOLISM
The liver and kidneys largely control the environment of the cell since the function of these two organs determines the constancy of composition of the extracellular fluids. The liver is largely concerned with stabilizing the organic constituents of the extracellular fluids that are required in the nutrition of the cell. Through storage, synthesis, conjugation, excretion and the liberation of organic constituents, the liver stabilizes the
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media in which the cells of the body function. Stabilization of the concentration of blood sugar as well as the removal and addition of amino acids to the circulation are well known illustrations of hepatic functions by which the nutrition of the cell is stabilized. The conservation of nitrogen by transamination and amino acid synthesis also occur in this organ. The liver plays a fundamental role in the utilization of 2-carbon fragments in the formation of complex molecules such as bile acids and cholesterol. The autoregulatory mechanisms by which the constancy of the internal environment is maintained are presided over by nervous and hormonal factors which regulate the metabolic activity of hepatic cells. Part of this autoregulatory mechanism appears to include the activation and inactivation of certain hormones by the liver. The ability of the liver to inactivate one hormone may be influenced by the action of another hormone on the liver. For example, recent evidence indicates that liver .slices can inactivate the antidiuretic hormone of the posterior pituitary gland and that this ability is influenced by the adrenal gland. 3t HORMONES AND HEPATIC FUNCTION
Estrogens
Hormone inactivation by the liver has been most convincingly demonstrated for estrogens. Clinical and laboratory evidence of disturbed hormonal balance in patients with extensive liver disease has beell reported repeatedly.29 Gynecomastia, cutaneous spider nevi, testicular atrophy and loss of libido in male patients with chronic liver disease were found to be associated with a high urinary excretion of estrogen and a low output of neutral 17-ketosteroids and gonadotropins. However, some of the gynecomastia associated with liver disease may be nutritional in origin. 30 Thyroxine
Evidence that the liver plays a role in the metabolism and excretion of thyroxine has been summarized elsewhere. 32 Recent studies with radioactive I-thyroxine support the earlier impression that injected thyroxine is largely excreted in bile by the rat. Thyroxine is excreted as such and in the form of degradation products that have been only partially identified. 33 The distribution of 1131 in the liver and gastrointestinal tract of rats following the administration of physiologic amounts of tagged thyroxine has led to the suggestion that thyroxine may undergo an enterohepatic circulation. This study also demonstrates that the main avenue of excretion of 1131 given as thyroxine to the rat is the liver and intestinal tract. 34
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Epinephrine
The mode of action of other hormonal effects on the liver has been clarified. The hyperglycemic-glycogenolytic effects of epinephrine and the hyperglycemic factor of the pancreas have been shown to be due to their action on the phosphorylase activity of liver tissue. The activity of this enzyme is the limiting factor in the series of reactions necessary to convert glycogen into glucose. The evidence indicates that these and other glycogenolytic substances act on an enzyme system which keeps a balance between active and inactive forms of phosphorylase in the liver. The glycogenolytic agents were shown to increase phosphorylase activity both in vitro and in vivo. The in vitro effect on phosphorylase activity paralleled their hyperglycemic effects in ViVO. 35 The hyperglycemia characteristic of early stages of fever has been ascribed to sympathico-adrenal stimulation. Studies on liver slices from rabbits given typhoid-paratyphoid vaccine demonstrated increased glycogenolysis in liver slice preparations. 36 It would be interesting to know the relative phosphorylase activity of liver tissue from normal and febrile hyperglycemic animals. Insulin
The storage of glucose by the liver is one of its most clearly defined functions. This function is impaired in the uncontrolled diabetic as evidenced by a low hepatic glycogen content in the presence of excessively high concentrations of blood sugar. There is a difference of opinion among investigators as to whether or not this deficit in glycogen storage in the diabetic is associated with an excess liberation of glucose from the liver or largely due to an impaired peripheral utilization of sugar. Recent evidence 4 obtained by comparison of systemic arterial and hepatic vein blood showed that the fasting normal subject as well as the fasting hyperglycemic diabetic liberated approximately 100 to 125 mg. of glucose per minute from the liver. There was no definite excess liberation of glucose by the liver in the absence of insulin under the circumstances of these observations. Similar results hSlve been reported on diabetic dogs. 37 Estimation of hepatic blood flow in these experiments was based upon the removal of bromsulphthalein from the circulation. The reduction in hepatic glucose liberation which insulin produced in the normal subject and which was accompanied by hypoglycemia was followed by increased hepatic glucose output in association with increased blood flow through the liver. These effects were ascribed to stimulation of epinephrine release secondary to hypoglyecmia. Insulin injected into diabetic patients reduced the glucose liberated by the liver but failed to alter the hepatic blood flow, presumably because no hypoglycemia was produced and epinephrine release did not occur. Recent chemical evidence38 indicates
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that insulin hypoglycemia is associated with a marked reduction in the epinephrine content of the blood. Studies of liver slices from diabetic animals 39 have shown that insulin increases the conversion of lactic acid and other precursors of 2-carbon fragments into fat. These findings are in accord with other observations indicating that one of the effects of insulin is to promote the storage of glucose as fat as well as glycogen. 4o Apparently, both types of carbohydrate storage depend upon an effect of insulin on the liver celL It has long been known41 that the hepatectomized animal is relatively refractory to insulin. Increased and decreased requirements for insulin have been observed in diabetic patients who developed fatty infiltration of the liver. Experimentally, it has been shown that the insulin requirement of adult dogs with a stabilized alloxan diabetes is increased by reducing the blood flow to the liver. 42 This is further evidence that the effectiveness of insulin is partially dependent upon hepatic function. That insulin increases the peripheral oxidation of glucose seems equally well established. 43 ACTH and Cortisone
Adrenal cortical extract causes a deposition of glycogen in the liver of adrenalectomized animals. This fact is the basis for the bioassay of adrenal cortical hormones. Compounds E and F have a similar effect. It has likewise been demonstrated that these compounds promote the deamination of amino acids, presumably by the liver, thereby increasing the formation of carbohydrate and fat from ingested protein. This increased catabolism or decreased anabolism of protein is responsible for the negative nitrogen balance associated with various stresses or with excessive adrenal cortical hormone administration. 44 This action by the adrenal corticoids is antagonistic to the anabolic effect of insulin which appears to be exerted peripherally as well as on the liver. 45 The fact that ketone body formation by the liver may be influenced by cortisone administration is additional evidence of an adrenal cortical effect on the degradation and interconversion of foodstuffs by the liver. 46 • 47 These effects may include the formation of carbohydrate from fat. 48 Clinical reports concerning the effect of ACTH and cortisone on hepatic disease are varied and conflicting. Biopsy evidence of reduced inflammation and fat infiltration was reported in 2 to 4 patients with cirrhosis who received ACTH for ten to fifteen days. There was also evidence of increased hematopoiesis and a greater appetite in all 4 patients. 49 Marked symptomatic improvement associated with a decreased serum bilirubin occurred in 5 patients with acute viral hepatitis treated with ACTH for nine to twenty-one days.60 Definite evidence of improvement, both laboratory and clinical, has
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been obtained in 1 patient with sarcoidosis of the liver treated with ACTH or cortisone for the past two years. Discontinuation of hormone administration on two occasions has led to a rapid return of the clinical manifestations of the disease. 51 The majority of investigators have found little or no laboratory evidence of permanent improvement in patients with cirrhosis given adrenal hormones, although temporary relief from pruritus associated with a reduction in the elevated blood bile salts was observed. 52 Serious complications due to hormone therapy have developed in some patients. Metabolic studies on patients with hepatic disease indicate that in general they excrete less than normal amounts of 17-ketosteroids in the urine. 53 , 54 'fhe administration of ACTH caused a definite increase in the urinary excretion of 17-ketosteroids and a proportionately greater rise in corticoid excretion in patients with cirrhosis. However, a smaller portion of excreted steroids was conjugated as glucuronidates than occurs normally. ACTH also appeared to produce a fasting hyperglycemia more readily in patients with advanced liver disease. 54 It was suggested that this could be due to a reduced capacity of the liver to store glycogen. Attention has been called to a group of young females with advanced cirrhosis of the liver whose clinical manifestations are suggestive of hyperadrenalism. These patients' manifestations included hirsutism, pigmented abdominal striae, obesity, acne, amenorrhea and "moon facies." Their urinary corticoid excretion was unusually high. 55 'rhese features appeared concomittantly with the onset of jaundice and did not appear to be a consequence of longstanding hepatic insufficiency. The most striking laboratory characteristic of this group was a marked elevation of the globulin fraction of the serum to values as high as 10 gm. per 100 cc.
AMINO ACIDS AND HEPATIC FUNCTION
It is reasonable to suppose that the increased urinary excretion of amino acids by the uncontrolled diabetic is, at least, partially due to a lack of the normal anabolic effect of insulin on the liver. 56 A marked increase in the urinary loss of amino acids also occurs following removal of the liver 57 and frequently occurs in liver disease. 58 Following hepatectomy, the increased excretion affects all of the amino acids except glycine, while in the diabetic animal the increase in glycine excretion is quite striking and may be due to excessive synthesis of this amino acid by the liver. CHOLESTEROL METABOLISM
It is generally recognized that the plasma concentration of cholesterol and the extent of ester forma.tion are normally regulated by the liver.
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It has been demonstrated that liver slices can synthesize cholesterol from acetic acid and other 2-carbon fragments 59-also that fat can be degraded to aceta-acetate and then converted into cholesterol without first being converted to acetate. 60 Factors that influence cholesterol synthesis by the liver are poorly defined although it has been demonstrated that fasting and caloric restriction reduce the synthesis of cholesterol from acetate by liver slices. 61 It has been proposed 62 that the increased cholesterol content of bile shown to result from thyroxine administration to the rat was due to increased synthesis of this substance by the hepatic cell. These same authors present evidence 63 that the cholesterol content of bile is independent of the cholesterol content of body fluids, but is related to the extent of cholesterol synthesis by the liver. The liver has likewise been shown to be the principal site of synthesis of plasma phospholipids. The ratio of cholesterol to lecithin in plasma is thought to be a factor in the tendency for cholesterol deposition to occur in the tissues. A relatively high lecithin content is believed to be a factor in stabilizing plasma cholesterol and presenting its deposition. Particle size is recognized as a factor in cholesterol.-lePQiit1,Qp,64 Qlldt·~rio$ ratios of cholesterol to lecithin may be expected to give rise to different degrees of dispersion of the lyophobic substance, cholesterol. The serum phospholipid and cholesterol values are normally related and disease of the liver is frequently associated with alterations in the cholesterolphospholipid ratio. 65 Experimental alterations in this ratio have likewise been produced by injury to the liver. 66 It has also been shown that the body can destroy cholestero1. 67 Experimental studies indicate that impairment of hepatic function reduces the ability of the dog to destroy cholesterol from exogenous sources and results in its accumulation in the plasma and liver. 66 Clinically, the instances in which hypercholesterolemia represents an inability on the part of the liver to destroy cholesterol remain unrecognized. Evidence is accumulating which suggests that a good many instances of hypercholesterolemia are at least partially due to exogenous cholesterol since dietary restriction of fat and cholesterol reduces the plasma concentration of the latter substance. This fact, taken with evidence of cholesterol destruction by the liver, would suggest that these patients have impairment in the liver's ability to destroy cholesterol, or else that they have an unusual absorption from the intestinal tract. Other experimental studies 68 suggest that another product of hepatic synthesis, cholic acid, may be a factor in producing hypercholesterolemia. It has been demonstrated in the rat that elevating the cholic acid content of the blood by obstruction of the common bile duct or cholate infusion will rapidly elevate the cholesterol content of the blood stream. Relief of obstruction of the common bile duct results in a decrease in plasma cholesterol without an increased excretion in the bile. The increased plasma cholesterol secondary to
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common bile duct obstruction has been established as hepatic in ori•
69
gmThe lipemia induced in the fowl by stilbesterol administration has
been shown to be dependent on hepatic function. 70 Estrogens have also been shown to influence the plasma lipoprotein and cholesterol content of human subjects with atherosclerosis.71 It seems probable that the temporary reduction in plasma cholesterol induced by estrogen administration may have been mediated by the liver. LABORATORY TESTS PERTAINING TO HEPATIC FUNCTION
Serum Alkaline Phosphatase The' origjn and significance of the serum phosphatase elevation in liver disease has been the subject of debate for a number of years. Some authors believe the serum increase to arise from"a failure of excretion by the liver of alkaline phosphatase that originate~ in the skeleton. Others believe that the major portion of the increase in serum alkaline phosphatase in hepatic disease results from regurgitation of the enzyme from the hepatic cell where it is formed and from which it is normally excreted in the bile. The concept one entertains may have some influence on the interpretation of clinical data and is therefore important from a practical as well as an academic point of view. Patients with acute extensive parenchymatous failure of the liver have stools poor in pigment, marked elevation of the serum bilirubin and only a relatively slight elevation of the alkaline phosphatase. If both bilirubin and phosphatase were similarly extrahepatic in origin, there should be a parallelism in their increase, since failure of excretion for both would occur. However, in such instances the concentration of serum bilirubin mounts rapidly as in an extrahepatic common bile duct obstruction, but the phosphatase values do not increase much and tend to level off while the bilirubin values continue to rise for some time. At the same time other signs of failure of the hepatic parenchyma occur, such as a reduction of cholesterol esters and urea content of blood. Recent experiments72 tend to confirm the hepatic origin of the serum phosphatase increase in liver disease. According to these results obstruction of the common bile duct of the dog causes a much greater rise in serum phosphatase during the subsequent twenth-four hours than occurs in the twenty-four hours following hepatectomy. In both instances there is a similar loss of excretory function but the liver is excluded as a source of enzyme in the hepatectomized animal. From these experiments it is also apparent that the diet prior to obstruction of the common bile duct influences the rate of enzyme increase in the serum following obstruction. These experiments are in direct contradictjon to the results of others that have been~reported previously. Recognition of 3. dissociation between the bilirubin and phosphatase
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increase in liver disease is important for the clinician. rfhe patient with a high serum bilirubin due to an excretory failure by the liver, who has at the same time a low serum alkaline phosphatase, may be expected to have extensive parenchymatous liver failure and is invariably a poor surgical risk. Such a circumstance is usually not mechanical in origin, or if it is, the defect is of long standing. Biopsy
Several studies have appeared recently in which biopsy material has been compared to the results of a battery of liver function tests. rfhese studies reveal that morphological evidence of liver damage may exist in the presence of normal liver function tests in some patients, while abnormal liver function tests may be obtained in instances where biopsy material appears to be perfectly normal morphologically.73 l"'hese considerations make it evident that both procedures may he essential to accurate diagnostic studies. Serum Choline Esterase and Other Tests
A comparison of the serum' choline esterase activity with ten other commonly employed liver function tests indicated it to be a valuable aid in following the progress of patients with acute hepatitis. Initially the serum choline esterase activity was depressed in all patients and the value rose as evidence of hepatocellular damage subsided. 74 However, the serum choline esterase activity does not always reflect a relapse in acute hepatitis and is usually norma] in chronic viral hepatitis. rfhe wide normal variation and overlap in a variety of diseases limits its usefulness as a practical test of liver function. 75 C~ompari.son of biopsy findings with a battery of liver function tests indicated that in patients with portal cirrhosis the best correlation was between the biopsy and bromsulphthalein excretion. In diagnosed cases of recurrent hepatitis the biopsy might appear normal while the function tests, particularly the thymol turbidity test, would be abnorma1. 76 A study of histologically proven cases of liver disease indicated that focal lesions usually did not alter parenchymal function significantly. The tests most frequently positive in focal condition were the alkaline serum phosphatase, total serum cholesterol and prompt reacting bilirubin. Bromsulphthalein was recommended as the best single screening test although admittedly not infallible.77 A comparison of electrophoretic patterns in patients with portal and biliary cirrhosis usually shows clear-cut differences since there is generally a steep fj-globulin peak in the latter condition. (jenerally, portal cirrhosis is characterized by serum cholesterol values that are less than normal while they are usually elevated in biliary eirrhosis. 78
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An attempt to use the glycemic response to epinephrine as a measure of hepatic glycogen gave rise to a wide variety of results. A seasonal difference in the glycemic response of an individual to epinephrine was demonstrated. A greater response occurred from October to May than from June to September. Two successive tests four days apart always gave a lower value on the second test. 79 Urobilinogen disappeared from the stools of normal subjects receiving 2 gm. of aureomycin daily. The bilirubin content of the stools increased and a small amount of urobilinogen persisted in the urine. The use of aureomycin could complicate the differential diagnosis of jaundice. 80 REFERENCES 1. Knisely, M. H., Bloch, E. H. and Warner, L.: Selective Phagocytosis 1. Microscopic Observations Concerning the Regulation of Blood Flow through the Liver and Other Organs and the Mechanism and Rate of Phagocytic Removal of Particles from the Blood: Det Kongelige Danske Videnskabernes Selskab, Biologiske Skrifter, Bind. IV, Nr. 7. KS?Sbenhavn, I Kommission Hos Ejnar Munksgaard, 1948. 2. Daniel, P. M. and Prichard, M. M. L.: Variations in the Circulation of the Portal Venous Blood within the Liver. J. Physiol. 114-: 521, 1951. 3. Maegraith, B. G.: Micro-Anatomy of the Hepatic Vascular System. In Liver Injury, p. 181, ed. by F. W. Hoffbauer, Josiah Macy, Jr. Foundation, New York, 1951. 4. a. Sherlock, S.: Hepatic Vein Catheterisation in Clinical Research. Proc. Inst. Med. Chicago 18: 335, 1951. b. Sherlock, S., Bearn, A. G. and Billing, B.: The Effect of Insulin on the Liver in Normal and Diabetic Man. In Liver Injury, p. 205, ed. by J1~. W. Hoffbauer, Josiah Macy, Jr. Foundation, New York, 1951. 5. Daniel, P. M. and Prichard, M. M. L.: Effects of Stimulation of the Hepatic Nerves and of Adrenaline upon the Circulation of the Portal Venous Blood within the Liver. J. Physiol. 114-: 538, 1951. 6. Deysach, L. J.: The Nature and Location of the "Sphincter Mechanisnl" in the Liver as Determined by Drug Actions and Vascular Injections. Am. J. Physiol. 132: 713,1941. 7. Thomas, W. D. and Essex, H. E.: Observations on the Hepatic Venous Circulation with. Special Reference to the Sphincteric Mechanism. Am. J. Physiol. 168: 303, 1949. 8. Frank, H. A., Seligman, A. M. and Fine, J.: Traumatic Shock. XIII. The Prevention of Irreversibility in Hemorrhagic Shock by Vive-Perfusion of the Liver. J. Clin. Investigation 25: 22, 1946. 9. Frank, H. A., Glotzer, P., Jacob, S. W. and Fine, J.: Hemorrhagic Shock in Eck Fistula Dogs. Am. J. Physiol. 167: 508, 1951. 10. Frank, H. A. and others: Traumatic Shock. XXII. Irreversibility of Hemorrhagic Shock and VDM Hypothesis. Am. J. Physiol168: 150, 1952. 11. Drury, D. R. and others: Renin Substrate and Renal Hypertension, Including a One-Stage Method for Eviscerating in the Rabbit. Am. J. Physiol. 164-: 630, 1951. 12. Page, I. H.: Influence of the-"Liver on Vascular Reactivity. Am. J. Physiol. 160: 421, 1950. 13. Cohn, R. and Parsons, H.: Relationship of Portal Hypertension and Irreversibility of Shock. Am. J. Physiol. 160: 437, 1950. 14. Raffucci, F. L. and Wangensteen, O. H.: Tolerance of Dogs to Occlusion of Entire Afferent Vascular Inflow to the Liver. "Surgical Forum" , American College of Surgeons. Philadelphia, W. B. Saunders Co., 1951.
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15. Hines, J. R. and Freeman, S.: Acute Hepatic Ischemia. Unpublished data. 16. R. Markowitz, J., Rappaport, A. and Scott, A. C.: Prevention of Liver Necrosis following Ligation of Hepatic Artery. Proc. Soc. Exper. BioI. & Med. 70: 305, 1949. b. Markowitz, J., Rappaport, A. and Scott, A. C.: The Function of the Hepatic Artery in the Dog. Am. J. Digest. Dis. 16: 344, 1949. 17. Tanturi, C., Swigart, L. L. and Campa, J. F.: Prevention of Death from Experimental Ligation of the Liver (Hepatic Proper) Branches of the Hepatic Artery. Surg., Gynec. & Obsta 91: 680, 1950. 18. Frank, H. A. and others: Traumatic Shock. XXI. Effectiveness of an Antibiotic in Experimental Hemorrhagic Shock. Am. J. Physiol. 168: 430, 1952. 19. Farquhar, J. D. and others: Studies on the Use of Aureomycin in Hepatic Disease. Ill. A Note on Aureomycin Therapy in Hepatic Coma. Am. J. M. Se. 220: 166, 1950. 20. Shaffer, J. M. and others: Studies on the Use of Aureomycin in Hepatic Disease. IV. Aureomycin Therapy in Chronic Liver Disease. Am. J. M. Sci., 220: 173, 1950. 21. Gyorgy, P. and others: Studies on the Use of Aureomycin in Hepatic Disease. 11. Effect of Aureomycin on Experimental Dietary Hepatic Necrosis. Am. J. M. Se. 220: 6, 1950. 22. a. Rappaport, A. M.: Experimental Ischemia of the Liver and Hepatic Coma. In Liver Injury, p. 146, ed. by F. W. Hoffbauer, Josiah Maey, Jr. Foundation, New York, 1951. b. Rappaport, A. M. and Lotto, W. N.: Experimental Hepatic Coma. Proc. Soc. Exper. BioI. & Med. 78: 14, 1951. 23. Reinhoff, W. F., Jr.: Ligation of the Hepatic and Splenic Arteries in the Treatment of Portal Hypertension with a Report of Six Cases. Johns Hopkins Hosp. Bull. 88: 368, 1951. 24. a. Kelty, R. H., Baggenstoss, A. H. and Butt, H. R.: The Relation of the Regenerated Hepatic Nodule to the Vascular Bed in Cirrhosis. Proc. Staff Meet., Mayo Clinic 25: 17, 1950. b. Daniel, P. M., Prichard, M. M. L. and Reynell, P. C.: The Portal Circulation in Experimental Cirrhosis of the Liver. J. Path. & Bact. 64: 53,1952. 25. Volwiler, W., Bollman, J. L. and Grindlay, J. H.: A Comparison of Two Types of Experimental Ascites. Proc. Staff Meet., Mayo Clinic 26: 31, 1950. 26. Bolton, C.: The Pathological Changes in the Liver Resulting from Passive Venous Congestion Experimentally Produced. J. Path. & Bact. 19: 258, 1914. 27. Nix, J. T., Flock, E. V. and Bollman, J. L.: Influence of Cirrhosis on Proteins of Cisternal Lymph. Am. J. Physiol. 164: 117, 1951. 28. Ivy, J. H. and Freeman, S.: Unpublished results on the origin of ascitic fluid produced experimentally in the dog. 29. Dohan, F. C. and others: Hormone Excretion in Liver Disease. J. Clin. Investigation 31: 481, 1952. 30. Kark, R. M., Morey, G. R. and Paynter, C. R.: Refeeding (Nutritional) Gynecomastia in Cirrhosis of the Liver. I. Clinical Observations. Am. J. M. Se. 220: 154, 1950. 31. Gaunt, R.: Adrenal Cortical Hormone and Related Hormones in Water Metabolism in Renal Function, p. 10, ed. by S. E. Bradley, Josiah Macy, Jr. Foundation, N. Y., 1950. 32. Monroe, R. A. and Turner, C. W·.: The Metabolism of Thyroxine. Missouri Agr. Exp. Sta., Res. Bull. 446, 1949. 33. Taurog, A., Briggs, F. N. and Chaikoff, I. L.: IU1-Labelled L-Thyroxine. I. An Unidentified1Excretion Product in Bile. J. BioI. Chem. 191: 29, 1951. 34. Johnson, H. W. and lAlbert, A.: The Excretion and Distribution of 1131 folfowingAdministration of Physiologic Amounts of Labeled Iodide, Diiodotyrosine and Thyroxine in the Rat. Endocrinology 48: 669, 1951. 35. Sutherland, E. W. and Cori, C. F.: Effect by Hyperglycemic-Glyco~enolytic
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Factor and Epinephrine on Liver Phosphorylase. J. BioI. Chem. 188: 531, 1951. 36. Fishgold, J. T., Grant, R., Field, J. and Hall, V. E.: Oxygen Consumption and Glucose Exchange in Vitro of Liver Slices from Febrile Rabbits. Am. J. PhysioI. 166: 113, 1951. 37. Crandal1: L. A., Jr. and Lipscomb, A.: A Direct Measurement of Hepatic Glucose Production in Experimental Diabetes Mellitus. Am. J. Physiol. 148: 312, 1947. 38. Weil-Malherbe, H. and Bone, A. D.: The Chemical Estimation of AdrenalineLike Substances in Blood,- Biochem. J. 51: 311, 1952. 39. a. Felts, J. M., Chaikoff, I. L. and Osborn, M. J.: Insulin and the Fate of Acetate and Formate in the Diabetic Liver. J. BioI. Chem. 193: 557,1951. b. Felts, J. M., Chaikoff, I. L. and Osborn, M. J.: Insulin and the Fate of Pyruvate in the Diabetic Liver. J.BioI. Chem. 193: 549, 1951. 40. a. Chernick, S. S. and others: Lipogenesis and Glucose Oxidation in the Liver of t.he Alloxan-Diabetic Rat. J. BioI. Chem. 186: 527,1950. Chernick, S. S. and Chaikoff, 1. L.: Insulin and Hepatic Utilization of Glucose for Lipogenesis. J. BioI. Chem. 186: 535, 1950. b. Stetten, D., Jr. and Boxer, G. E.: Studies in Carbohydrate Metabolism. Ill. Metabolic Defects in Alloxan Diabetes. J. BioI. Chem. 156: 271,1944. 41. Markowitz, J., Mann, F. C. and Bollman, J. L.: The Glycogenic Function of Skeletal Muscle in the Dehepatized Dog, with Special Reference to the Role of Insulin Therein. Am. J. PhysioI. 87: 566, 1929. 42. Koide, S. and Freeman, S.: Effect of Eck-Fistula Formation on Alloxan Diabetic Dogs. Am. J. Physiol. 167: 193, 1951. 43. Wick, A. N. and others: Action of Insulin on the Extra-Hepatic Tissues. J. BioI. Chem. 188: 241, 1951. 44. Hoberman, H. D.: Endocrine Regulation of Amino Acid and Protein Metabolism During Fasting. Yale J. BioI. & Med. 22: 341, 1949-50. 45. Russell, J. A. and Cappiello, M.: The Relationship of Temperature and Insulin Dosage to the Rise in Plasma Amino Nitrogen in the Eviscerated Rat. Endocrinology 44: 127, 1949. 46. Tepperman, J. and DeWitt, J. M.: Effects of Pitui'tary Growth Hormone and Cortisone Administration in Vivo on Ketogenesis by Surviving Liver Slices Obtained from Hypophysectomized Rats. Fed. Proc. 10: 136, 1951. 47. Kinsell, L. W. and others: Hormonal Regulation of Fat Metabolism. 1. Effects of ACTH and of Certain Steroid Hormones upon Fasting-Induced Hyperketonemia. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., Vo!. I, p. 308. 48. Segaloff, A. and Many, A. S.: The Effect of ACTH on Glucose and Ketone Production in Phloridzinized Rats. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., VoI. 1., p. 301. 49. Brown, H., Jager, B. V. and Tyler, F. H.: ACTH in Cirrhosis of the Liver. Am. J. Med. 10: 770, 1951. 50. Colbert, J. W. and others: The Use of ACTH in Acute Viral Hepatitis. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., Vo!. I, p.371. 51. Foxworthy, D. T. and Freeman, S.: Unpublished data. Hines Hospital for Veterans, Hines, Illinois. 52. Williams, C. F. and Flink, E. B.: Corticotropin Therapy of Chronic Liver Disease. J. Lab. & Clin. Med. 39: 888, 1952. 53. Butt, H. R. and others: Observations on the Effect of Cortisone Acetate on Two·Patients with Hepatic Disease. J. Lab. & Clin. Med. 37: 870,1951. 54. Bongiovanni, A. M. and Eisenmenger, W. J.: Observations During the Administration of ACTH to Patients with Chronic Liver Disease. Proc. 2nd Clin. ACTH Conf., Philadelphia, 1951, The Blakiston Co., Vol. I, p.390. 55. Bongiovanni, A. M. and Eisenmenger, W. J.: Adrenal Cortical Metabolism in Chronic Liver Disease. J. Clin. Endocrinol. 11: 152, 1951.
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56. Ivy, J. H., Svec, M. and Freeman, S.: Free Plasma Level and Urinary :Excretion of Eighteen Amino Acids in Normal and Diabetic Dogs. Am. tT. Physiol. 167: 182, 1951. 57. Freeman, S. and Svec, M.: Effect of Complete Hepatectomy upon Plasma Concentration and Urinary Excretion of Eighteen Amino Acids. Am. tJ. Physiol. 167: 201, 1951. 58. Dunn, M. S. and others: Urinary Excretion of Amino Acids in Liver Disease. J. Clin. Investigation 29: 302, 1950. 59. Bloch, K., Borek, E. and Rittenberg, D.: Synthesis of Cholesterol in Surviving Liver. J. BioI. Chem. 162: 441, 1946. 60. Curran, G. L.: Utilization of Acetoacetic Acid in Cholesterol Synthesis by Surviving Rat Liver. J. BioI. Chem. 191: 775, 1951. 61. Tomkins, G. M. and Chaikoff, 1. L.: Cholesterol Synthesis by Liver.!. Influence of Fasting and of Diet. J. BioI. Chem. 196: 569, 1952. 62. Byers, S. O. and Friedman, M.: Production and Excretion of Cholesterol in Mammals. VII. Biliary Cholesterol: Increment and Indicator of Hepatic Synthesis of Cholesterol. Am. J. Physiol. 168: 297, 1952. 63. Byers, S. O. and Friedman, M.: Observations Concerning the Production and Excretion of Cholesterol in Mammals. J. Exper. Med. 95: 19, 1952. 64. Gofman, J. W. and others: Blood Lipids and Human Atherosclerosis. Circulation 2: 161, 1950. 65. Albrink, M. J., Man, E. B. and Peters, J. P.: Serum Lipids in Infectious Hepatitis and Obstructive Jaundice. J. Clin. Investigation 29: 781, 1950. 66. Bailey, R. O. and Freeman, S.: Hepatic Function and Cholesterol Tolerance in the Dog. J. Lab. & Clin. Med. 39: 184, 1952. 67. Gould, R. G.: The Comparative Metabolism of Dietary and Endogenous Cholesterol Differentiated by Use of Radioactive Carbon. Circulation 2: 467, 1950. 68. Byers, S. O. and Friedman, M.: Effect of Various Bile Acids on the Hypercholesteremia Following Biliary Obstruction in the Rat. Am. J .Physiol. 168: 138, 1952. 69. Bloom, W. L. and others: Glycogen Fractions of Liver and Muscle. J. BioI. Chem. 188: 631, 1951. 70. Ranney, R. E., Chaikoff, I. L. and Dobson, :E. L.: A Procedure for Functional Hepatectomy of the Unanesthetized Fowl. Am ..1. Physiol. 165: 588, 1951. 71. Barr, D. P.: The Influence of Estrogens on Lipoproteins in Atherosclerosis. 65th Annual Meeting of the American Association of Physicians, Atlantic City, N. J., May, 1952. 72. Freeman, S.: Comparison of Effects of Hepatectomy and of Common Bile Duct Obstruction on Serum Phosphatase of Adult Dogs. Am. J. Physiol. 164-: 792, 1951. 73. Berk, J. E. and Shay, H.: Liver Biopsy and Liver Function Tests. J.A.M.A. 14-8: 109, 1952. 74. Vorhaus, L. J., Scudamore, H. H. and Kark, R. M.: Measurement of Serun1 Cholinesterase Activity: A Useful Test in the Management of Acute Hepatitis. Am. J. M. Se. 221: 140, 1951. 75. Mann, J. D., Mandel, W. I. and Knowlton, M. A.: Serum Cholinesterase Activity in Liver Disease. J. Lab. & Clin. Med. 39: 543, 1952. 76. Moyer, J. H. and Wurl, O. A.: Liver Biopsy: Correlation with Clinical and Biochemical Observations. Am. J. M. Se. 221: 28, 1951. 77. Ricketts,W. E.: Pathological Liver with Minimal or No Change in "Liver Tests." Am. J. M. Se. 221:.287, 1951 78. Ricketts, W. E. and Sterling, K.: Comparative Studies of "Liver Tests" and Electrophoretic Analyses of Serum Proteins in Portal and Biliary Cirrhosis. Am. J. M. Se. 221: 38, 1951. 79. Altschule, M. D. and Sigel, E. P.: Inadequacy of the Glycemic Reaction to Epinephrine as a Measure of Hepatic Glycogen. Am. J. M. Se. 222: 50, 1951. 80. GaIt, J. and Hunter, R. B.: The Effect of Aureomycin on Certain Liver Function Tests and Blood Coagulation. Am. J. M. Se. 220: 508, 1950.