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DISORDERS OF BLOOD-LIPIDS IN RENAL DISEASE
672
Occasional
Survey
DISORDERS OF BLOOD-LIPIDS IN RENAL DISEASE D. G. CRAMP J. F. MOORHEAD M. R. WILLS Chemical Pathology and Nephrology, Departments of
Royal
Free
Hospital, London NW3 2QG
Hyperlipidæmia is a feature not only of
characteristic the nephrotic syndrome but also of chronic renal disease without the features of that syndrome. There is evidence for disordered lipid metabolism in patients with chronic renal disease. In these patients the disordered lipid metabolism, the precise cause of which is unknown, is characterised by hypertriglyceridæmia, the ætiology of which is probably multifactorial. Hyperlipidæmia is an important potential risk factor in the ætiology of cardiovascular disease, which may be a leading cause of death in patients undergoing long-term maintenance hæmodialysis therapy.
Sum ary
INTRODUCTION
HYPERLIPIDÆMIA is
a
characteristic feature of the
nephrotic syndrome, but is also well recognised in patients with renal failure who do not have the clinical features of the nephrotic syndrome.l-4 Furthermore, at least one group of workershas presented evidence that cardiac and vascular disorders are an important cause of mortality in patients undergoing long-term maintenance hoemodialysis. This evidence, from the U.S.A., may not accurately represent the European experience.’,’ The characteristic feature of the disordered lipid metabolism in chronic renal failure is hypertriglyceridaemia. This increase in plasma-triglyceride concentration may occur because of an increased rate of input, a decreased removalrate, or possibly a combination of both. The availability of metabolic precursors is an important factor in regulating the rate of endogenous triglyceride synthesis and hence the rate of entry into the circulation. Triglyceride is removed from the circulation by lipoprotein lipase, an enzyme whose activity may be markedly affected by nutritional and hormonal factors.
,
The purpose of this survey is to review the evidence for either increased endogenous triglyceride synthesis or impaired triglyceride removal, and to suggest that the disorders of lipid metabolism in patients with renal disease are not necessarily different in those with and without the clinical features of the nephrotic syndrome. Nephrotic syndrome presents clinically with hypoproteinxmia, proteinuria, and hyperlipidaemia. A striking feature is a pronounced increase in protein turnover related to increased urinary protein loss and increased hepatic protein synthesis. LIPID DISORDERS IN NEPHROSIS
Early studies of the hyperlipidæmia of nephrotic syndrome emphasised the temporal and causal relations between hypoalbuminaemia and hyperlipidaemia.
Recent in-vivo and in-vitro investigations tend to confirm that there is an increased inflow of lipid into the circulation and that in rats with induced nephrosis increased hepatic lipoprotein synthesis is the primary event.*-’’ The report of increased plasma-triglyceride synthesis in human nephrotic syndrome 10 confirms these animal experimental findings. There is also evidence in the rat that the hepatic uptake of nonesterified fatty acids and chylomicron triglycerides is above normal." It could be postulated that triglyceride clearance is impaired by inhibition of lipoprotein lipase in chronic renal failure. McKenzie and Nestel 11 drew attention to this possibility. A decrease in lipoproteinlipase activity in adipose tissue has been demonstrated in rats with experimental nephrotic syndrome,12 but post-heparin plasma-lipase activity in these animals was within the normal ranger as it is in man in similar conditions. Kekki and Nikkilä, using the endogenous glycerol labelling method of Reaven et al.,1G studied the endogenous triglyceride turnover-rate in fourteen adults with nephrotic syndrome. It was thought that, since the disappearance- of tritiated glycerol and its subsequent reappearance in very-lowdensity lipoprotein (v.L.D.L.) can be described in enzyme kinetic terms, information about the activity of the clearing enzymes could be inferred. Ten of their fourteen patients demonstrated a significant increase of hepatic triglyceride production, but also had evidence of a removal defect. When the logarithm of triglyceride concentration and turnover-rate was separately related to the serum-albumin concentration and to the daily urinary protein loss, there was a significant correlation between the triglyceride concentration and the serum-albumin content. These observations could be explained, for it has been shown that apolipoprotein formation is increased in nephrotic animals as part of the compensatory mechanism involving a general stimulation of hepatic protein synthesis." Apolipoprotein production is increased by promoting hepatic triglyceride synthesis,le The dramatic reversal of triglyceridmia upon infusion of albumin described by Bogdonoff et al.19 and Kekki and Nikkilä,15 however, suggests that this is an unlikely mechanism. It has also been suggested 15 that the stimulated triglyceride synthesis in nephrotic syndrome is markedly influenced by the free fatty acid (F.F.A.)/albumin ratio, as indeed may be the activity of lipoprotein lipase. BLOOD-LIPIDS IN RENAL FAILURE
There have been relatively few studies of the bloodlipids in patients with renal failure, and none of the distribution of lipid abnormalities in relation to the pathogenesis of renal disease. It has, however, been established that in a large.proportion of these patients, either undialysed or on regular dialysis treatment, there is an increase in fasting plasma-triglyceride concentrations and that these changes are usually associated with low post-heparin lipolytic activity. Gutman et al .21reported that hypertriglyceridaemia was present in eleven of fourteen undialysed patients and in seventeen of twenty-five hxmodialysed patients with chronic renal failure. Post-heparin lipoproteinlipase activity was reduced in twenty-one of the
,
673
twenty-two patients in whom it was assayed. After hsmodialysis the triglyceride concentrations returned to within the normal range, and post-heparin lipolytic activity improved significantly. However, plasmatriglyceride concentrations and post-heparin lipolytic activity had returned to their predialysis values within 12-36 hours of haemodialysis. These findings seem to be consistent with
some
mulated metabolites environment. LIPID
or
METABOLISM
defect due either to accuto an altered hormonal AND
CARBOHYDRATE
INTOLERANCE IN NEPHROSIS
Abnormalities in lipid metabolism are often associated with carbohydrate intolerance, which is also a recognised feature of patients with uraemia. In a group of patients with chronic renal failure, Losowsky and Kenward1 reported abnormal glucose tolerance after intravenous glucose loading, with a fall in F.F.A. concentration which was of greater magnitude and duration than in a group of normal subjects. Bagdade et al.2 reported that in both dialysed and undialysed urxmic patients plasma-immunoreactive-insulin concentrations were increased. ’ In contrast, Kaye et al.4 reported that there was no significant difference between the mean immunoreactive insulin concentrations in a group of undialysed urasmic patients when compared with the control although the mean glucose concentration was increased in the ursemic group. Furthermore, these workers were unable to demonstrate any correlation between insulin and triglyceride concentrations in either the control subjects or in uraemic patients; the insulin concentrations showed -a similar distribution in both the groups. They concluded that these findings were consistent with the concept of the accumulation of insulin antagonists in chronic renal failure rather than any alteration in insulin release or synthesis.
subjects,
LIPID
FRACTIONS INVOLVED IN NEPHROSIS
hypertriglyceridxmia of chronic renal failure is usually associated with an increase in cholesterol and neutral lipids. The hyperlipidaemia of chronic renal failure is, moreover, characterised by an increase in the pre-&bgr;-lipoprotein fraction. Since a high proportion of the lipid fraction of the pre-/3-lipoproteins is triglyceride, the increase in pre-/3-lipoprotein is consistent with the finding of hypertriglyceridæmia. The
Cohen and Lindall 21 demonstrated that on ultracentrifugal analysis of the lipoprotein fractions from patients with chronic renal failure there was an abnormality in the V.L.D.L. species. Furthermore, Lewis et al.22 reported results from their laboratory which suggested a qualitative abnormality in the V.L.D.L. of patients with chronic renal failure. Of eleven patients with chronic renal failure and a hyperlipidæmia, eight had an increase in the V.L.D.L. content and nine had a v.L.D.L. cholesterol content higher than normal, resulting in a lower than normal triglyceride/cholesterol ratio in the V.L.D.L. fraction.
An abnormal response in plasma-immunoreactive-growth-hormone concentration has also been reported in uraemic patients after either oral or intraThe abnormal growthvenous glucose loading.23-25 hormone response has been attributed both to glucose
tion.
intolerance 25 and to the relative protein malnutrition found in patients with chronic renal failure.233 It has also been suggested that the continuing hyperlipidaemia in successfully transplanted patients is due to the continuous corticosteroid therapy 26,27 However, in a recent report 28 there was a lower prevalence of hyperlipidxmia in stable renal-transplant patients on alternate-day corticosteroid therapy. CONCLUSION
patients with chronic renal failure it seems that triglyceride concentrations may increase as a consequence of either (i) reduced triglyceride clearance from the plasma compartment; (ii) excessive hepatic synthesis of triglyceride as a result of carbohydrate intolerance; or (iii) stimulation of hepatic synthesis from F.F.A. released from tissue triglyceride stores by lipolytic hormones. Possibly more than one of these mechanisms may be operating concurrently. The precise mechanisms of the hyperlipidsemia may not be known. During the past few years, however, evidence has been accumulating that cardiovascular disease is a leading cause of death among patients undergoing long-term maintenance hasmodialysis therapy. Potential risk factors such as hyperlipidaemia, hypertension, vascular calcification, and left ventricular hypertrophy must be further evaluated. In
REFERENCES
Losowsky, M. S., Kenward, P. H. J. Lab. clin. Med. 1968, 71, 736. Bagdade, J. D., Porte, D. L., Bierman, E. L. New Engl. J. Med. 1968, 279, 181. 3. Brøns, M., Christensen, N. L., Horder, M. Acta med. scand. 1972, 192, 119. 4. Kaye, J. P., Moorhead, J. F., Wills, M. R. Clinica chim. Acta, 1973, 44, 301. 5. Lindner, A., Charra, B., Sherrard, D. J., Scribner, B. H. New Engl. J. Med. 1974, 290, 697. 6. Moorhead, J. F., Baillod, R. Unpublished. 7. de Wardener, H. Personal communication. 8. Marsh, J. B., Whereat, A. F. J. biol. Chem. 1959, 234, 3196. 9. Radding, C. M., Steinberg, D. M. J. clin. Invest. 1960, 39, 1560. 10. McKenzie, I. F. L., Nestel, P. J. ibid. 1968, 47, 1685. 11. Malmendier, C. L. ibid. 1962, 41, 185. 12. Gutman, A., Shafrir, E. Am. J. Physiol. 1963, 205, 702. 13. Rosenman, R. H., Byers, S. O. Proc. Soc. exp. Biol. 1960, 103, 31. 14. Nikkilä, E. A., Gräsbeck, R. Acta med scand. 1954, 150, 39. 15. Kekki, M., Nikkilä, E. A. Eur. J. clin. Invest. 1971, 1, 345. 16. Reaven, G. M., Hill, D. B., Gross, R. C., Farquhar, J. W. J. clin. Invest. 1965, 44, 1826. 17. Marsh, J. B., Drabkin, D. L. Metabolism, 1960, 9, 946. 18. Rudeman, N. B., Richards, K. C., Valles de Bourges, V., Jones, A. L. J. Lipid Res. 1968, 9, 613. 19. Bogdonoff, M. D., Linhart, J., Klein, R. F., Estes, E. H. J. clin. Invest. 1961, 40, 1024. 20. Gutman, R. A., Uy, A., Shalhoub, R. J., Wade, A. D., O’Connell, J. M. B., Recant, L. Am. J. clin. Nutr. 1973, 26, 165. 21. Cohen, S. L., Lindall, A. W. J. Lab. clin. Med. 1969, 74, 863. 22. Lewis, B., Chait, A., Sissons, P. in Advances in Experimental Medicine and Biology (edited by R. Fumagalli, G. Ricci, and S. 1. 2.
23. 24.
25. HORMONES
AND
NEPHROTIC HYPERLIPIDÆMIA
The role ofhormones in nephrotic hyperlipidaemia is not clear. In the ursemic patients reported by Kaye et a1.4 there was a significant increase in the mean
plasma-immunoreactive-growth-hormone
concentra-
26.
27. 28.
Gorini); vol. XXXVIII, p. 157. New York, 1973. A. D., Lowy, C., Fraser, T. R., Spitz, I. M., Rubenstein, A. A., Bersohn, I. Lancet, 1968, ii, 798. Horton, E. S., Johnson, C., Lebovitz, H. F. Ann. intern. Med. 1968, 68, 63. Orskøv, H. L., Christensen, N. J. Scand. J. clin. Lab. Invest. 1971, 27, 51. Caseratto, A., Marchioro, T. L., Goldsmith, R., Bagdade, J. D. Lancet, 1974, i, 481. Ghosh, R., Evans, D. B., Tomlinson, S. A., Calne, R. Y. Transplantation, 1973, 15, 521. Beaumont, J. E., Galla, J. H., Luke, R. G., Rees, E. D., Siegel, R. R. Lancet, 1975, i, 599.
Wright,
Occasional
Survey
DISORDERS OF BLOOD-LIPIDS IN RENAL DISEASE D. G. CRAMP J. F. MOORHEAD M. R. WILLS Chemical Pathology and Nephrology, Departments of
Royal
Free
Hospital, London NW3 2QG
Hyperlipidæmia is a feature not only of
characteristic the nephrotic syndrome but also of chronic renal disease without the features of that syndrome. There is evidence for disordered lipid metabolism in patients with chronic renal disease. In these patients the disordered lipid metabolism, the precise cause of which is unknown, is characterised by hypertriglyceridæmia, the ætiology of which is probably multifactorial. Hyperlipidæmia is an important potential risk factor in the ætiology of cardiovascular disease, which may be a leading cause of death in patients undergoing long-term maintenance hæmodialysis therapy.
Sum ary
INTRODUCTION
HYPERLIPIDÆMIA is
a
characteristic feature of the
nephrotic syndrome, but is also well recognised in patients with renal failure who do not have the clinical features of the nephrotic syndrome.l-4 Furthermore, at least one group of workershas presented evidence that cardiac and vascular disorders are an important cause of mortality in patients undergoing long-term maintenance hoemodialysis. This evidence, from the U.S.A., may not accurately represent the European experience.’,’ The characteristic feature of the disordered lipid metabolism in chronic renal failure is hypertriglyceridaemia. This increase in plasma-triglyceride concentration may occur because of an increased rate of input, a decreased removalrate, or possibly a combination of both. The availability of metabolic precursors is an important factor in regulating the rate of endogenous triglyceride synthesis and hence the rate of entry into the circulation. Triglyceride is removed from the circulation by lipoprotein lipase, an enzyme whose activity may be markedly affected by nutritional and hormonal factors.
,
The purpose of this survey is to review the evidence for either increased endogenous triglyceride synthesis or impaired triglyceride removal, and to suggest that the disorders of lipid metabolism in patients with renal disease are not necessarily different in those with and without the clinical features of the nephrotic syndrome. Nephrotic syndrome presents clinically with hypoproteinxmia, proteinuria, and hyperlipidaemia. A striking feature is a pronounced increase in protein turnover related to increased urinary protein loss and increased hepatic protein synthesis. LIPID DISORDERS IN NEPHROSIS
Early studies of the hyperlipidæmia of nephrotic syndrome emphasised the temporal and causal relations between hypoalbuminaemia and hyperlipidaemia.
Recent in-vivo and in-vitro investigations tend to confirm that there is an increased inflow of lipid into the circulation and that in rats with induced nephrosis increased hepatic lipoprotein synthesis is the primary event.*-’’ The report of increased plasma-triglyceride synthesis in human nephrotic syndrome 10 confirms these animal experimental findings. There is also evidence in the rat that the hepatic uptake of nonesterified fatty acids and chylomicron triglycerides is above normal." It could be postulated that triglyceride clearance is impaired by inhibition of lipoprotein lipase in chronic renal failure. McKenzie and Nestel 11 drew attention to this possibility. A decrease in lipoproteinlipase activity in adipose tissue has been demonstrated in rats with experimental nephrotic syndrome,12 but post-heparin plasma-lipase activity in these animals was within the normal ranger as it is in man in similar conditions. Kekki and Nikkilä, using the endogenous glycerol labelling method of Reaven et al.,1G studied the endogenous triglyceride turnover-rate in fourteen adults with nephrotic syndrome. It was thought that, since the disappearance- of tritiated glycerol and its subsequent reappearance in very-lowdensity lipoprotein (v.L.D.L.) can be described in enzyme kinetic terms, information about the activity of the clearing enzymes could be inferred. Ten of their fourteen patients demonstrated a significant increase of hepatic triglyceride production, but also had evidence of a removal defect. When the logarithm of triglyceride concentration and turnover-rate was separately related to the serum-albumin concentration and to the daily urinary protein loss, there was a significant correlation between the triglyceride concentration and the serum-albumin content. These observations could be explained, for it has been shown that apolipoprotein formation is increased in nephrotic animals as part of the compensatory mechanism involving a general stimulation of hepatic protein synthesis." Apolipoprotein production is increased by promoting hepatic triglyceride synthesis,le The dramatic reversal of triglyceridmia upon infusion of albumin described by Bogdonoff et al.19 and Kekki and Nikkilä,15 however, suggests that this is an unlikely mechanism. It has also been suggested 15 that the stimulated triglyceride synthesis in nephrotic syndrome is markedly influenced by the free fatty acid (F.F.A.)/albumin ratio, as indeed may be the activity of lipoprotein lipase. BLOOD-LIPIDS IN RENAL FAILURE
There have been relatively few studies of the bloodlipids in patients with renal failure, and none of the distribution of lipid abnormalities in relation to the pathogenesis of renal disease. It has, however, been established that in a large.proportion of these patients, either undialysed or on regular dialysis treatment, there is an increase in fasting plasma-triglyceride concentrations and that these changes are usually associated with low post-heparin lipolytic activity. Gutman et al .21reported that hypertriglyceridaemia was present in eleven of fourteen undialysed patients and in seventeen of twenty-five hxmodialysed patients with chronic renal failure. Post-heparin lipoproteinlipase activity was reduced in twenty-one of the
,
673
twenty-two patients in whom it was assayed. After hsmodialysis the triglyceride concentrations returned to within the normal range, and post-heparin lipolytic activity improved significantly. However, plasmatriglyceride concentrations and post-heparin lipolytic activity had returned to their predialysis values within 12-36 hours of haemodialysis. These findings seem to be consistent with
some
mulated metabolites environment. LIPID
or
METABOLISM
defect due either to accuto an altered hormonal AND
CARBOHYDRATE
INTOLERANCE IN NEPHROSIS
Abnormalities in lipid metabolism are often associated with carbohydrate intolerance, which is also a recognised feature of patients with uraemia. In a group of patients with chronic renal failure, Losowsky and Kenward1 reported abnormal glucose tolerance after intravenous glucose loading, with a fall in F.F.A. concentration which was of greater magnitude and duration than in a group of normal subjects. Bagdade et al.2 reported that in both dialysed and undialysed urxmic patients plasma-immunoreactive-insulin concentrations were increased. ’ In contrast, Kaye et al.4 reported that there was no significant difference between the mean immunoreactive insulin concentrations in a group of undialysed urasmic patients when compared with the control although the mean glucose concentration was increased in the ursemic group. Furthermore, these workers were unable to demonstrate any correlation between insulin and triglyceride concentrations in either the control subjects or in uraemic patients; the insulin concentrations showed -a similar distribution in both the groups. They concluded that these findings were consistent with the concept of the accumulation of insulin antagonists in chronic renal failure rather than any alteration in insulin release or synthesis.
subjects,
LIPID
FRACTIONS INVOLVED IN NEPHROSIS
hypertriglyceridxmia of chronic renal failure is usually associated with an increase in cholesterol and neutral lipids. The hyperlipidaemia of chronic renal failure is, moreover, characterised by an increase in the pre-&bgr;-lipoprotein fraction. Since a high proportion of the lipid fraction of the pre-/3-lipoproteins is triglyceride, the increase in pre-/3-lipoprotein is consistent with the finding of hypertriglyceridæmia. The
Cohen and Lindall 21 demonstrated that on ultracentrifugal analysis of the lipoprotein fractions from patients with chronic renal failure there was an abnormality in the V.L.D.L. species. Furthermore, Lewis et al.22 reported results from their laboratory which suggested a qualitative abnormality in the V.L.D.L. of patients with chronic renal failure. Of eleven patients with chronic renal failure and a hyperlipidæmia, eight had an increase in the V.L.D.L. content and nine had a v.L.D.L. cholesterol content higher than normal, resulting in a lower than normal triglyceride/cholesterol ratio in the V.L.D.L. fraction.
An abnormal response in plasma-immunoreactive-growth-hormone concentration has also been reported in uraemic patients after either oral or intraThe abnormal growthvenous glucose loading.23-25 hormone response has been attributed both to glucose
tion.
intolerance 25 and to the relative protein malnutrition found in patients with chronic renal failure.233 It has also been suggested that the continuing hyperlipidaemia in successfully transplanted patients is due to the continuous corticosteroid therapy 26,27 However, in a recent report 28 there was a lower prevalence of hyperlipidxmia in stable renal-transplant patients on alternate-day corticosteroid therapy. CONCLUSION
patients with chronic renal failure it seems that triglyceride concentrations may increase as a consequence of either (i) reduced triglyceride clearance from the plasma compartment; (ii) excessive hepatic synthesis of triglyceride as a result of carbohydrate intolerance; or (iii) stimulation of hepatic synthesis from F.F.A. released from tissue triglyceride stores by lipolytic hormones. Possibly more than one of these mechanisms may be operating concurrently. The precise mechanisms of the hyperlipidsemia may not be known. During the past few years, however, evidence has been accumulating that cardiovascular disease is a leading cause of death among patients undergoing long-term maintenance hasmodialysis therapy. Potential risk factors such as hyperlipidaemia, hypertension, vascular calcification, and left ventricular hypertrophy must be further evaluated. In
REFERENCES
Losowsky, M. S., Kenward, P. H. J. Lab. clin. Med. 1968, 71, 736. Bagdade, J. D., Porte, D. L., Bierman, E. L. New Engl. J. Med. 1968, 279, 181. 3. Brøns, M., Christensen, N. L., Horder, M. Acta med. scand. 1972, 192, 119. 4. Kaye, J. P., Moorhead, J. F., Wills, M. R. Clinica chim. Acta, 1973, 44, 301. 5. Lindner, A., Charra, B., Sherrard, D. J., Scribner, B. H. New Engl. J. Med. 1974, 290, 697. 6. Moorhead, J. F., Baillod, R. Unpublished. 7. de Wardener, H. Personal communication. 8. Marsh, J. B., Whereat, A. F. J. biol. Chem. 1959, 234, 3196. 9. Radding, C. M., Steinberg, D. M. J. clin. Invest. 1960, 39, 1560. 10. McKenzie, I. F. L., Nestel, P. J. ibid. 1968, 47, 1685. 11. Malmendier, C. L. ibid. 1962, 41, 185. 12. Gutman, A., Shafrir, E. Am. J. Physiol. 1963, 205, 702. 13. Rosenman, R. H., Byers, S. O. Proc. Soc. exp. Biol. 1960, 103, 31. 14. Nikkilä, E. A., Gräsbeck, R. Acta med scand. 1954, 150, 39. 15. Kekki, M., Nikkilä, E. A. Eur. J. clin. Invest. 1971, 1, 345. 16. Reaven, G. M., Hill, D. B., Gross, R. C., Farquhar, J. W. J. clin. Invest. 1965, 44, 1826. 17. Marsh, J. B., Drabkin, D. L. Metabolism, 1960, 9, 946. 18. Rudeman, N. B., Richards, K. C., Valles de Bourges, V., Jones, A. L. J. Lipid Res. 1968, 9, 613. 19. Bogdonoff, M. D., Linhart, J., Klein, R. F., Estes, E. H. J. clin. Invest. 1961, 40, 1024. 20. Gutman, R. A., Uy, A., Shalhoub, R. J., Wade, A. D., O’Connell, J. M. B., Recant, L. Am. J. clin. Nutr. 1973, 26, 165. 21. Cohen, S. L., Lindall, A. W. J. Lab. clin. Med. 1969, 74, 863. 22. Lewis, B., Chait, A., Sissons, P. in Advances in Experimental Medicine and Biology (edited by R. Fumagalli, G. Ricci, and S. 1. 2.
23. 24.
25. HORMONES
AND
NEPHROTIC HYPERLIPIDÆMIA
The role ofhormones in nephrotic hyperlipidaemia is not clear. In the ursemic patients reported by Kaye et a1.4 there was a significant increase in the mean
plasma-immunoreactive-growth-hormone
concentra-
26.
27. 28.
Gorini); vol. XXXVIII, p. 157. New York, 1973. A. D., Lowy, C., Fraser, T. R., Spitz, I. M., Rubenstein, A. A., Bersohn, I. Lancet, 1968, ii, 798. Horton, E. S., Johnson, C., Lebovitz, H. F. Ann. intern. Med. 1968, 68, 63. Orskøv, H. L., Christensen, N. J. Scand. J. clin. Lab. Invest. 1971, 27, 51. Caseratto, A., Marchioro, T. L., Goldsmith, R., Bagdade, J. D. Lancet, 1974, i, 481. Ghosh, R., Evans, D. B., Tomlinson, S. A., Calne, R. Y. Transplantation, 1973, 15, 521. Beaumont, J. E., Galla, J. H., Luke, R. G., Rees, E. D., Siegel, R. R. Lancet, 1975, i, 599.
Wright,