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Interferon decreases serum lipid peroxidation products of hepatitis C patients
Free Radical Biology & Medicine, Vol. 16, pp. 131-133, 1994 Printed in the USA. All rights reserved.
0891-5849/94 $6.00 + .00 Copyright © 1993 Pergamon Press Ltd.
Brief Communication INTERFERON DECREASES SERUM LIPID PEROXIDATION PRODUCTS OF HEPATITIS C PATIENTS
VICTORIA HIGUERAS, ,~NGEL RAYA, JOSI~ M A N U E L RODRIGO, t~ M I G U E L ANGEL SERRA, t¢ J O A Q U i N ROMA, and FRANCISCO J. ROMERO* *Experimental Toxicology and Neurotoxicology Unit, Department of Physiology and +Department of Medicine, School of Medicine and Dentistry, University of Valencia and *Gastroenterology Unit, University Hospital, Valencia, Spain (Received 17 December 1992; Accepted 14 May 1993) Abstract--Thiobarbituric acid reactive substances (TBARS) concentration in serum has been determined in healthy subjects and in patients suffering acute hepatitis and chronic cases of hepatitis C. Treatment with interferon of the chronic active hepatitis C patients, 5 x l06 U three times a week during 2 months, led in those patients whose SGPT activity normalized in serum, to a concomitant decrease in serum TBARS content. The possible theoretical involvement of peroxidation and antioxidants in this benefficial effect of interferon in hepatitis C patients is discussed. The results presented confirm the value of TBARS as laboratory test in the management of liver diseases and as a useful tool for the study of pathogenic and/or therapeutic mechanisms of this viral infection. Keywords--Free radicals, Interferon, Hepatitis C, Malonaldehyde
cat effects associated with oxidative stress in cells and tissues. 1'2 The relevance and applicability of the TBARS assay as diagnostic index of lipid peroxidation and peroxidative tissue injury have been recently reviewed) Unlike reactive free radicals, aldehydes are rather long lived and can, therefore, diffuse from their sight of origin and reach and attack distant targets from the initial radical event,~ thus circulate in blood. Moreover, lipid peroxides are transported in the systemic circulation by low- and high-density lipoproteins. There is a large body of literature indicating the general sensitivity and reproducibility of the TBARS assay in animal tissues and human serum in different diseases. 4-'0 Acute and chronic hepatitis are inflammatory processes of very peculiar and different ethiology, but have as common denominator an imposed stress to the liver cell that promotes, among other signs, an increase of TBARS in the sera of these patients. 4 Hepatitis C, i.e., transfusion-related hepatitis not attributable to hepatitis A virus or hepatitis B virus, accounts for the majority of transfusion-transmitted disease. The existence of an agent causing non-A, non-B hepatitis was documented by Alter et al.~ ' and named hepatitis C virus (HCV) thereafter. The main goal of this work was to establish the modifications of serum
INTRODUCTION
Inflammation associated with infectious and degenerative diseases, as well as some others, leads to the activation of the so-called inflammatory cells. This activation, by means of several mechanisms involving neutrophils, endothelial cells, etc., might promote oxidative stress. Lipid peroxidation often occurs in response to oxidative stress and a great variety of aldehydes is formed when lipid hydroperoxides break down in biological systems.' A convenient and frequently used assay for quantification of lipid peroxidation is the thiobarbituric acid (TBA) assay, which measures various aldehydes derived from lipid hydroperoxides. In view of the lack of specificity for any aldehyde, this assay is more correctly referred to as the measurement of thiobarbituric acid reacting substances (TBARS). In addition to the fact that the detection of these aldehydes might be the expression of the extent of the damage, these aldehydes generated endogenously are involved in some pathophysiologiAddress correspondence to: Francisco J. Romero, Experimental Toxicology and Neurotoxicology Ur.it, Department of Physiology, School of Medicine and Dentistry, University of Valencia, Av. Blasco Ib~lnez, 17, E-460 l0 Valencia, Spain. 131
132
V. HIGUERAS t't a/. Table t. Criteria for the Diagnosis of Acute and Chronic Hepatitis, and Collection of Samples SGPT Value (mU/ml)
Immunological Tests
<22 >250
Negative Anti-HBclgM+, a n t i - H D + or anti-HCV4 Anti-HCV+ Anti-HCV+
Healthy subjects Acute hepatitis Chronic hepatitis Interferon-treated a
>22 <22
Sample Collected
During acute phase Before interferon Once SGPT <22
a These patients are the same group of chronic active hepatitis C.
TBARS concentration in acute and chronic hepatitis C patients and the effect of interferon treatment of the latter group on this parameter. MATERIALS AND METHODS
Health), subjects Healthy subjects were selected on the basis of general physical examination. They showed no abnormal laboratory findings including liver function tests. No previous history of hepatitis and/or chronic alcoholism was evident.
Analytical conditions TBARS were determined according to a modification of the procedure of Buege and Aust. 2 as follows. One volume of sample is mixed throughly with two volumes of a stock solution of 15% w/v trichloroacetic acid, 0.375% w/v thiobarbituric acid, and 0.25 N hydrochloric acid. The combination of sample and stock solution is heated for 30 min in a boiling water bath. After cooling, the flocculent precipitate is removed by centrifugation at 1,000 X g for I0 rain. The absorbance of the sample is determined at 535 nm and the TBARS concentration calculated using 1.56 × l05 M-~cm -l as molar extinction coefficient.
Patients Twenty patients diagnosed of hepatitis on the basis of clinical symptoms and immunological tests, were studied. Ten of these patients were diagnosed of acute hepatitis and 10 of chronic active hepatitis C by laboratory and clinical findings. Laboratory criteria for acute and chronic hepatitis and the time points of the collection of samples are shown in Table 1. The diagnosis of chronic active hepatitis C was confirmed by needle biopsy in all cases.
Interferon treatment The interferon treatment was applied to patients of active chronic hepatitis C, once this diagnosis was established according to the criteria in Table 1. Briefly, 5 x 106 U of interferon were administered three times a week during 2 months. The 10 patients in which SGPT values returned to the normal range after interferon treatment were selected.
Statistical analysis Data are presented as the mean + SD and the statistical significance between the different groups was established by means of the Student's t-test. RESULTS AND DISCUSSION
Table 2 shows the concentration of TBARS in sera of healthy subjects and in patients diagnosed of acute hepatitis, chronic active hepatitis C and this latter group treated with interferon. The increase in serum TBARS concentration in acute hepatitis is in the range of those previously reported. The values of the chronic group remain highly significant when compared with the healthy subjects, and the chronic pa-
Table 2. Thiobarbituric Reactive Substances Concentration in Serum
Group
Collection and preparation of plasma Whole blood specimens, 1 ml each, were placed in test tubes containing 5 mg of EDTA. The mixed sample was centrifuged for 5 min at 3,000 rpm and the plasma separated. Samples were stored at -40°C until use.
Healthy subjects Acute hepatitis Chronic hepatitis C Interferon-treated a
T B A R S (uM)
n
Significance vs. Control
7.43 12.07 11.02 8.97
11 l0 l0 l0
-p < 0.0001 p < 0.0001 Not significant
+_ 1.28 _+ 1.80 +_ 0.79 _+ 2.20 b
a These patients are the same group of chronic active hepatitis C. b Significantly different from chronic hepatitis C group, p < 0.015.
Lipid peroxidation in hepatitis C
tients treated with interferon showed no statistical differences when compared with the healthy subjects. The mechanisms by which interferon ameliorates the laboratory findings in sera of hepatitis C patients are still not clear. It has been reported that interferon inducers showed a protective effect against pulmonary oxygen toxicity? 2 In this study, a decrease in TBARS content of the whole lung and a concomitant increase of pulmonary SOD activity in the interferon inducers-treated rats were observed. If the interferon treatment promotes, in fact, an increase in the antioxidant mechanisms of the liver of these patients is still an open question, but would indeed fit in the results presented. The regulation of peroxidative processes during health and disease occurs through intervention by lipid and water-soluble antioxidants, as well as by specific antioxidant enzymes. Some of these antioxidants are directly related with the immune response under normal conditions ~3 and even under conditions of a compromised immune response as in human immunodeficiency virus (HIV) infection. 14 Infection with the HIV is also associated with an increase in serum TBARS ~5 and a systemic glutathione deficiency. ~6 Moreover, intracellular thiols regulate the transcription of the HIV. 17 A recent report has demonstrated some remissions of chronic active hepatitis C associated with zidovudine therapy in HIV-1 carriers. ~a Whether HCV and HIV might involve in a similar way cellular antioxidants is still an open question. The findings presented and the evidence to data in the literature suggest a) the role of radicals and lipid peroxidation during the development of hepatitis C, and b) that the mechanism by which the benefficial effect of the interferon treatment is exerted on these patients might involve antioxidant metabolism. Nonetheless, the present report confirms the value of TBARS as a laboratory test in the management of hepatitis C and remains a valuable tool for the study of the pathophysiology of different diseases. Acknowledgements - - Part of this work was financially supported by grant nos. 92/0403 from the Fondo de Investigaciones Sanitarias de la Seguridad Social, Spain and PM92-0146 from the DGICYT, Spain, to F.J.R.
133 REFERENCES
1. Esterbauer, H.; Schaur, R. J.: Zollner, H. Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes. Free Radic. Biol. Med. 11:81-128:1991. 2. Buege, J. A.; Aust, S. D. Microsomal lipid peroxidation. Methods Enzymol. 12:302-310; 1978. 3. Janero, D. R. Malondialdehyde and thiobarbituric acid-reactivity as diagnostic indices of lipid peroxidation and peroxidative tissue injury. Free Radio. Biol. Med. 9:515-540; 1990. 4. Suematsu, T.; Kamada, T.: Abe, H.; Kikuchi, S.; Yagi, K. Serum lipid peroxide level in patients suffering from liver diseases. Clin. Chim. Acta 79:267-270: 1977. 5. Ohkawa, H.; Ohishi, N.: Yagi, K. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Anal. Biochem. 95:351-358; 1979. 6. Santos, M. T.; Valles, J.; Aznar, J.; Vilches, J. Determination of plasma malondialdehyde-like material and its clinical application in stroke patients. J. Clin. Pathol. 33:973-976: 1980. 7. Aznar, J.; Santos, M. T.; Valles, J.; Sala, J. Serum malondialdehyde-like material (MDA-LM) in acute myocardial infarction. J. Clin. Pathol. 36:712-715; 1983. 8. Yagi, K. Lipid peroxides and human diseases. Chem. Phys. Lipids 45:337-351; 1987. 9. Alessio, H. M.; Goldfarb, A. H.; Cutler, R. G. MDA content increases in fast- and slow-twitch skeletal muscle with intensity of exercise in a rat. Am. J. Physiol. 24:C874-C877; 1988. 10. Asayama, K.; Shiki, Y.; Ito, H.; Hasegawa, O.; Miyao, A.; Hayashibe, H.; Dobashi, K.; Kato, K. Antioxidant enzymes and lipoperoxide in blood in uremic children and adolescents. Free Radic. Biol. Med. 9:105-109; 1990. 11. Alter, H. J.; Purcell, R. H.; Holland, P. V.; Feinstone, S. M.: Morrow, A. G.; Moritsugu, Y. Clinical and serological analysis of transfusion-associated hepatitis. Lancet ii:838-841 ; 1975. 12. Kikkawa, Y.; Yano, S.; Skoza, L. Protective effect of interferon inducers against hyperoxic pulmonary damage. Lab. Invest. 50:62-71 ; 1984. 13. Liang, C. M.; Lee, N.; Cattell, D.; Liang, S. M. Glutathione regulates interleukin-2 activity in cytotoxic T-cells. J. Biol. Chem. 264:13519-13523; 1989. 14. Garewal, H. S.; Ampel, N. M.; Watson, R. R.; Prabhala, R. H.; Dols, C. L. A preliminary trial of beta-carotene in subjects infected with the human immunodeficiency virus. J. Nutr. 122:728-732: 1992. 15. SiSnnerborg, A.; Carlin, G.; Akerlund, B.; Jarstrand, C. Increased production of malondialdehyde in patients with HIV infection. Scand ,L hfect. Dis. 20:287-290; 1988. 16. Buhl, R.; Holroyd, K. J.; Mastrangeli, A.; Cantin, A. M.; Jaffe, H. A.; Wells, F. B.; Saltini, C.; Crystal, R. G. Systemic glutathione deficiency in symptom-free HIV-seropositive individuals. Lancet iii:1294-1298; 1989. 17. Staal, F. J. T.; Roeder, M.; Herzenberg, L. A.; Herzenberg, L. A. Intracellular thiols regulate activation of nuclear factor r-B and transcription of human immunodeficiency virus. Proc. Natl. Acad Sci. USA 87:9943-9947; 1990. 18. Vento, S.; Garofano, T.; Diperri, G.; Cruciani, M.; Concia, E.; Basseti, D. Zidovudine therapy associated with remission of chronic active hepatitis C in HIV- 1 carriers. AIDS 5:776; 1991.
0891-5849/94 $6.00 + .00 Copyright © 1993 Pergamon Press Ltd.
Brief Communication INTERFERON DECREASES SERUM LIPID PEROXIDATION PRODUCTS OF HEPATITIS C PATIENTS
VICTORIA HIGUERAS, ,~NGEL RAYA, JOSI~ M A N U E L RODRIGO, t~ M I G U E L ANGEL SERRA, t¢ J O A Q U i N ROMA, and FRANCISCO J. ROMERO* *Experimental Toxicology and Neurotoxicology Unit, Department of Physiology and +Department of Medicine, School of Medicine and Dentistry, University of Valencia and *Gastroenterology Unit, University Hospital, Valencia, Spain (Received 17 December 1992; Accepted 14 May 1993) Abstract--Thiobarbituric acid reactive substances (TBARS) concentration in serum has been determined in healthy subjects and in patients suffering acute hepatitis and chronic cases of hepatitis C. Treatment with interferon of the chronic active hepatitis C patients, 5 x l06 U three times a week during 2 months, led in those patients whose SGPT activity normalized in serum, to a concomitant decrease in serum TBARS content. The possible theoretical involvement of peroxidation and antioxidants in this benefficial effect of interferon in hepatitis C patients is discussed. The results presented confirm the value of TBARS as laboratory test in the management of liver diseases and as a useful tool for the study of pathogenic and/or therapeutic mechanisms of this viral infection. Keywords--Free radicals, Interferon, Hepatitis C, Malonaldehyde
cat effects associated with oxidative stress in cells and tissues. 1'2 The relevance and applicability of the TBARS assay as diagnostic index of lipid peroxidation and peroxidative tissue injury have been recently reviewed) Unlike reactive free radicals, aldehydes are rather long lived and can, therefore, diffuse from their sight of origin and reach and attack distant targets from the initial radical event,~ thus circulate in blood. Moreover, lipid peroxides are transported in the systemic circulation by low- and high-density lipoproteins. There is a large body of literature indicating the general sensitivity and reproducibility of the TBARS assay in animal tissues and human serum in different diseases. 4-'0 Acute and chronic hepatitis are inflammatory processes of very peculiar and different ethiology, but have as common denominator an imposed stress to the liver cell that promotes, among other signs, an increase of TBARS in the sera of these patients. 4 Hepatitis C, i.e., transfusion-related hepatitis not attributable to hepatitis A virus or hepatitis B virus, accounts for the majority of transfusion-transmitted disease. The existence of an agent causing non-A, non-B hepatitis was documented by Alter et al.~ ' and named hepatitis C virus (HCV) thereafter. The main goal of this work was to establish the modifications of serum
INTRODUCTION
Inflammation associated with infectious and degenerative diseases, as well as some others, leads to the activation of the so-called inflammatory cells. This activation, by means of several mechanisms involving neutrophils, endothelial cells, etc., might promote oxidative stress. Lipid peroxidation often occurs in response to oxidative stress and a great variety of aldehydes is formed when lipid hydroperoxides break down in biological systems.' A convenient and frequently used assay for quantification of lipid peroxidation is the thiobarbituric acid (TBA) assay, which measures various aldehydes derived from lipid hydroperoxides. In view of the lack of specificity for any aldehyde, this assay is more correctly referred to as the measurement of thiobarbituric acid reacting substances (TBARS). In addition to the fact that the detection of these aldehydes might be the expression of the extent of the damage, these aldehydes generated endogenously are involved in some pathophysiologiAddress correspondence to: Francisco J. Romero, Experimental Toxicology and Neurotoxicology Ur.it, Department of Physiology, School of Medicine and Dentistry, University of Valencia, Av. Blasco Ib~lnez, 17, E-460 l0 Valencia, Spain. 131
132
V. HIGUERAS t't a/. Table t. Criteria for the Diagnosis of Acute and Chronic Hepatitis, and Collection of Samples SGPT Value (mU/ml)
Immunological Tests
<22 >250
Negative Anti-HBclgM+, a n t i - H D + or anti-HCV4 Anti-HCV+ Anti-HCV+
Healthy subjects Acute hepatitis Chronic hepatitis Interferon-treated a
>22 <22
Sample Collected
During acute phase Before interferon Once SGPT <22
a These patients are the same group of chronic active hepatitis C.
TBARS concentration in acute and chronic hepatitis C patients and the effect of interferon treatment of the latter group on this parameter. MATERIALS AND METHODS
Health), subjects Healthy subjects were selected on the basis of general physical examination. They showed no abnormal laboratory findings including liver function tests. No previous history of hepatitis and/or chronic alcoholism was evident.
Analytical conditions TBARS were determined according to a modification of the procedure of Buege and Aust. 2 as follows. One volume of sample is mixed throughly with two volumes of a stock solution of 15% w/v trichloroacetic acid, 0.375% w/v thiobarbituric acid, and 0.25 N hydrochloric acid. The combination of sample and stock solution is heated for 30 min in a boiling water bath. After cooling, the flocculent precipitate is removed by centrifugation at 1,000 X g for I0 rain. The absorbance of the sample is determined at 535 nm and the TBARS concentration calculated using 1.56 × l05 M-~cm -l as molar extinction coefficient.
Patients Twenty patients diagnosed of hepatitis on the basis of clinical symptoms and immunological tests, were studied. Ten of these patients were diagnosed of acute hepatitis and 10 of chronic active hepatitis C by laboratory and clinical findings. Laboratory criteria for acute and chronic hepatitis and the time points of the collection of samples are shown in Table 1. The diagnosis of chronic active hepatitis C was confirmed by needle biopsy in all cases.
Interferon treatment The interferon treatment was applied to patients of active chronic hepatitis C, once this diagnosis was established according to the criteria in Table 1. Briefly, 5 x 106 U of interferon were administered three times a week during 2 months. The 10 patients in which SGPT values returned to the normal range after interferon treatment were selected.
Statistical analysis Data are presented as the mean + SD and the statistical significance between the different groups was established by means of the Student's t-test. RESULTS AND DISCUSSION
Table 2 shows the concentration of TBARS in sera of healthy subjects and in patients diagnosed of acute hepatitis, chronic active hepatitis C and this latter group treated with interferon. The increase in serum TBARS concentration in acute hepatitis is in the range of those previously reported. The values of the chronic group remain highly significant when compared with the healthy subjects, and the chronic pa-
Table 2. Thiobarbituric Reactive Substances Concentration in Serum
Group
Collection and preparation of plasma Whole blood specimens, 1 ml each, were placed in test tubes containing 5 mg of EDTA. The mixed sample was centrifuged for 5 min at 3,000 rpm and the plasma separated. Samples were stored at -40°C until use.
Healthy subjects Acute hepatitis Chronic hepatitis C Interferon-treated a
T B A R S (uM)
n
Significance vs. Control
7.43 12.07 11.02 8.97
11 l0 l0 l0
-p < 0.0001 p < 0.0001 Not significant
+_ 1.28 _+ 1.80 +_ 0.79 _+ 2.20 b
a These patients are the same group of chronic active hepatitis C. b Significantly different from chronic hepatitis C group, p < 0.015.
Lipid peroxidation in hepatitis C
tients treated with interferon showed no statistical differences when compared with the healthy subjects. The mechanisms by which interferon ameliorates the laboratory findings in sera of hepatitis C patients are still not clear. It has been reported that interferon inducers showed a protective effect against pulmonary oxygen toxicity? 2 In this study, a decrease in TBARS content of the whole lung and a concomitant increase of pulmonary SOD activity in the interferon inducers-treated rats were observed. If the interferon treatment promotes, in fact, an increase in the antioxidant mechanisms of the liver of these patients is still an open question, but would indeed fit in the results presented. The regulation of peroxidative processes during health and disease occurs through intervention by lipid and water-soluble antioxidants, as well as by specific antioxidant enzymes. Some of these antioxidants are directly related with the immune response under normal conditions ~3 and even under conditions of a compromised immune response as in human immunodeficiency virus (HIV) infection. 14 Infection with the HIV is also associated with an increase in serum TBARS ~5 and a systemic glutathione deficiency. ~6 Moreover, intracellular thiols regulate the transcription of the HIV. 17 A recent report has demonstrated some remissions of chronic active hepatitis C associated with zidovudine therapy in HIV-1 carriers. ~a Whether HCV and HIV might involve in a similar way cellular antioxidants is still an open question. The findings presented and the evidence to data in the literature suggest a) the role of radicals and lipid peroxidation during the development of hepatitis C, and b) that the mechanism by which the benefficial effect of the interferon treatment is exerted on these patients might involve antioxidant metabolism. Nonetheless, the present report confirms the value of TBARS as a laboratory test in the management of hepatitis C and remains a valuable tool for the study of the pathophysiology of different diseases. Acknowledgements - - Part of this work was financially supported by grant nos. 92/0403 from the Fondo de Investigaciones Sanitarias de la Seguridad Social, Spain and PM92-0146 from the DGICYT, Spain, to F.J.R.
133 REFERENCES
1. Esterbauer, H.; Schaur, R. J.: Zollner, H. Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes. Free Radic. Biol. Med. 11:81-128:1991. 2. Buege, J. A.; Aust, S. D. Microsomal lipid peroxidation. Methods Enzymol. 12:302-310; 1978. 3. Janero, D. R. Malondialdehyde and thiobarbituric acid-reactivity as diagnostic indices of lipid peroxidation and peroxidative tissue injury. Free Radio. Biol. Med. 9:515-540; 1990. 4. Suematsu, T.; Kamada, T.: Abe, H.; Kikuchi, S.; Yagi, K. Serum lipid peroxide level in patients suffering from liver diseases. Clin. Chim. Acta 79:267-270: 1977. 5. Ohkawa, H.; Ohishi, N.: Yagi, K. Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction. Anal. Biochem. 95:351-358; 1979. 6. Santos, M. T.; Valles, J.; Aznar, J.; Vilches, J. Determination of plasma malondialdehyde-like material and its clinical application in stroke patients. J. Clin. Pathol. 33:973-976: 1980. 7. Aznar, J.; Santos, M. T.; Valles, J.; Sala, J. Serum malondialdehyde-like material (MDA-LM) in acute myocardial infarction. J. Clin. Pathol. 36:712-715; 1983. 8. Yagi, K. Lipid peroxides and human diseases. Chem. Phys. Lipids 45:337-351; 1987. 9. Alessio, H. M.; Goldfarb, A. H.; Cutler, R. G. MDA content increases in fast- and slow-twitch skeletal muscle with intensity of exercise in a rat. Am. J. Physiol. 24:C874-C877; 1988. 10. Asayama, K.; Shiki, Y.; Ito, H.; Hasegawa, O.; Miyao, A.; Hayashibe, H.; Dobashi, K.; Kato, K. Antioxidant enzymes and lipoperoxide in blood in uremic children and adolescents. Free Radic. Biol. Med. 9:105-109; 1990. 11. Alter, H. J.; Purcell, R. H.; Holland, P. V.; Feinstone, S. M.: Morrow, A. G.; Moritsugu, Y. Clinical and serological analysis of transfusion-associated hepatitis. Lancet ii:838-841 ; 1975. 12. Kikkawa, Y.; Yano, S.; Skoza, L. Protective effect of interferon inducers against hyperoxic pulmonary damage. Lab. Invest. 50:62-71 ; 1984. 13. Liang, C. M.; Lee, N.; Cattell, D.; Liang, S. M. Glutathione regulates interleukin-2 activity in cytotoxic T-cells. J. Biol. Chem. 264:13519-13523; 1989. 14. Garewal, H. S.; Ampel, N. M.; Watson, R. R.; Prabhala, R. H.; Dols, C. L. A preliminary trial of beta-carotene in subjects infected with the human immunodeficiency virus. J. Nutr. 122:728-732: 1992. 15. SiSnnerborg, A.; Carlin, G.; Akerlund, B.; Jarstrand, C. Increased production of malondialdehyde in patients with HIV infection. Scand ,L hfect. Dis. 20:287-290; 1988. 16. Buhl, R.; Holroyd, K. J.; Mastrangeli, A.; Cantin, A. M.; Jaffe, H. A.; Wells, F. B.; Saltini, C.; Crystal, R. G. Systemic glutathione deficiency in symptom-free HIV-seropositive individuals. Lancet iii:1294-1298; 1989. 17. Staal, F. J. T.; Roeder, M.; Herzenberg, L. A.; Herzenberg, L. A. Intracellular thiols regulate activation of nuclear factor r-B and transcription of human immunodeficiency virus. Proc. Natl. Acad Sci. USA 87:9943-9947; 1990. 18. Vento, S.; Garofano, T.; Diperri, G.; Cruciani, M.; Concia, E.; Basseti, D. Zidovudine therapy associated with remission of chronic active hepatitis C in HIV- 1 carriers. AIDS 5:776; 1991.