Low blood selenium levels in alcoholics with and without advanced liver disease. Correlations with clinical and nutritional status

Validation and Comparison of Two Dietary Indexes for Predicting Nonalcoholic Fatty Liver Disease in US Adults

BACKGROUND

Two indexes have been used to describe dietary inflammatory potential: the experiment-based dietary total antioxidant capacity (TAC) and the literature-derived dietary inflammatory index (DII). How robustly each index represents dietary inflammatory potential and the risk of nonalcoholic fatty liver disease (NAFLD) has not yet been established.

OBJECTIVES

We investigated the relation between dietary inflammatory potential and NAFLD, and compared the abilities of the TAC and DII scores to predict NAFLD in US adults.

METHODS

Cross-sectional data from 12,410 participants aged 20-80 y in the NHANES from 2011 to 2018 were identified. TAC and DII scores were calculated using 2 d of 24-h dietary recall data. We examined the association between dietary index and risk of NAFLD using linear and logistic regression models.

RESULTS

Higher energy-adjusted TAC (E-TAC) and inversely energy-adjusted DII (IE-DII) scores (both representing more anti-inflammatory diets) were associated with lower hepatic steatosis index (HSI) and US fatty liver index (USFLI) values after adjusting for potential covariates, and the association for each SD increase in the IE-DII was stronger than the E-TAC (β estimates for HSI: -0.39 compared with -0.25; P-difference = 0.036). In modeling the risk of NAFLD, we observed that participants with IE-DII scores in the highest quartile had the lowest ORs for NAFLD as assessed by either the HSI (OR: 0.77; 95% CI: 0.62, 0.96; P-trend = 0.023) or USFLI (OR: 0.48; 95% CI: 0.35, 0.68; P-trend <0.0001). TAC scores were also associated with NAFLD as assessed by the USFLI.

CONCLUSIONS

An anti-inflammatory diet is beneficial for reducing the risk of NAFLD in US adults. The DII is a stronger predictor of hepatic measures than the TAC, and we recommend that future hepatic health studies use the DII to estimate dietary inflammatory potential.

Increased serum selenium levels are associated with reduced risk of advanced liver fibrosis and all-cause mortality in NAFLD patients: National Health and Nutrition Examination Survey (NHANES) III

INTRODUCTION AND OBJECTIVES

Selenium supplementation has been shown to have therapeutic value in chronic liver disease. We aimed to investigate the association between serum selenium, severity of liver fibrosis, and mortality in patients with Nonalcoholic Fatty Liver Disease (NAFLD).

PATIENTS OR MATERIAL AND METHODS

A total of 33,944 patients were identified from the Third National Health and Nutrition Examination Survey. NAFLD was diagnosed by hepatic ultrasound after the exclusion of other forms of liver diseases. The severity of liver fibrosis was determined by NAFLD Fibrosis Score >0.676. Multivariate logistic regression analysis was used to investigate the relationship between serum selenium level and liver fibrosis. Association between serum selenium and all-cause mortality in NAFLD patients was also evaluated.

RESULTS

Multivariate logistic regression analysis demonstrated odds ratio of advanced liver fibrosis (NFS > 0.676) was significantly reduced with increasing serum selenium levels; OR 0.55, [95% CI 0.32-0.94] in the highest selenium quartile. On stratification analysis, the following populations had a significantly reduced risk of advanced liver fibrosis: non-Hispanic white = OR 0.41 [0.24,0.68]; female = OR 0.32 [0.15-0.66] and age >47 = OR 0.47 [0.28-0.79]. The relationship was significant regardless of BMI as noted by BMI ≤ 30 Kg/m2= OR 0.42 [0.19-0.91] and BMI > 30 Kg/m2=OR 0.52 [0.28-0.97]. Hazard ratio for all-cause mortality was HR 0.72 [0.56-0.95].

CONCLUSIONS

The risk of advanced liver fibrosis is inversely associated with serum selenium levels, particularly in older patients, Caucasians, and females. All-cause mortality decreased with increased selenium levels. Selenium may play a role in the prevention of liver fibrosis in NAFLD.

Trace element deficiency is highly prevalent and associated with infection and mortality in patients with alcoholic hepatitis

BACKGROUND

Malnutrition is common in patients with alcohol-related liver disease and is associated with outcome in patients with alcoholic hepatitis. Trace elements (cobalt, copper, iron, selenium and zinc) are micronutrients essential for many cellular processes including antioxidant pathways. The prevalence and relevance of trace element deficiency is unknown in alcoholic hepatitis.

AIM

To determine the prevalence of trace element deficiency and its association with clinical outcomes in patients with alcoholic hepatitis.

METHODS

Serum was obtained from patients with alcoholic hepatitis, alcohol-related cirrhosis and healthy volunteers as part of clinical trials, cohort studies and a biobank. Trace element concentration was measured by inductively coupled plasma mass spectrometry. Association of trace element levels with development of infection within 90 days and mortality within 28 and 90 days was evaluated by multivariate logistic regression.

RESULTS

Sera from 302 patients with alcoholic hepatitis, 46 with alcohol-related cirrhosis and 15 healthy controls were analysed for trace element concentration. The prevalence of zinc deficiency (85%) and selenium deficiency (67%) in alcoholic hepatitis was higher than in alcohol-related cirrhosis (72% [p=0.04] and 37% [p<0.001], respectively). Zinc, selenium, copper and chromium were significantly different between groups. Iron deficiency was a predictor of development of infection within 90 days. Zinc deficiency was a predictor of mortality within 28 and 90 days.

CONCLUSION

Trace element deficiency in patients with alcoholic hepatitis is highly prevalent and associated with infection and mortality. Supplementation with selected trace elements may improve clinical outcomes in this patient group but further insight is required of their biological and clinical effects.

Selenium deficiency occurs in some patients with moderate-to-severe cirrhosis and can be corrected by administration of selenate but not selenomethionine: a randomized controlled trial

BACKGROUND

Selenomethionine, which is the principal dietary form of selenium, is metabolized by the liver to selenide, which is the form of the element required for the synthesis of selenoproteins. The liver synthesizes selenium-rich selenoprotein P (SEPP1) and secretes it into the plasma to supply extrahepatic tissues with selenium.

OBJECTIVES

We conducted a randomized controlled trial to determine whether cirrhosis is associated with functional selenium deficiency (the lack of selenium for the process of selenoprotein synthesis even though selenium intake is not limited) and, if it is, whether the deficiency is associated with impairment of selenomethionine metabolism.

DESIGN

Patients with Child-Pugh (C-P) classes A, B, and C (mild, moderate, and severe, respectively) cirrhosis were supplemented with a placebo or supranutritional amounts of selenium as selenate (200 or 400 μg/d) or as selenomethionine (200 μg/d) for 4 wk. Plasma SEPP1 concentration and glutathione peroxidase (GPX) activity, the latter due largely to the selenoprotein GPX3 secreted by the kidneys, were measured before and after supplementation.

RESULTS

GPX activity was increased more by both doses of selenate than by the placebo in C-P class B patients. The activity was not increased more by selenomethionine supplementation than by the placebo in C-P class B patients. Plasma selenium was increased more by 400 μg Se as selenate than by the placebo in C-P class C patients. Within the groups who responded to selenate, there was a considerable variation in responses.

CONCLUSION

These results indicate that severe cirrhosis causes mild functional selenium deficiency in some patients that is associated with impaired metabolism of selenomethionine. This trial was registered at clinicaltrials.gov as NCT00271245.

Metabolism of ethanol and associated hepatotoxicity

Over the last three decades, direct hepatotoxic effects of ethanol were established, some of which were linked to redox changes produced by NADH generated via the alcohol dehydrogenase (ADH) pathway and shown to affect the metabolism of lipids, carbohydrates, proteins, and purines. It was also determined that ethanol can be oxidized by a microsomal ethanol oxidizing system (MEOS) involving a specific cytochrome P-450; this newly discovered ethanol-inducible cytochrome P-450 (P-450 IIEi) contributes to ethanol metabolism, tolerance, energy wastage (with associated weight loss), and the selective hepatic perivenular toxicity of various xenobiotics. Their activation by P-450IIEi now provides an understanding of the increased susceptibility of the heavy drinker to the toxicity of industrial solvents, anaesthetic agents, commonly prescribed drugs, over-the-counter analgesics, and chemical carcinogens. P-450 induction also explains depletion (and toxicity) of nutritional factors such as vitamin A. As a consequence, treatment with vitamin A and other nutritional factors is beneficial, but must take into account a narrowed therapeutic window in alcoholics who have increased needs for nutrients and also display an enhanced susceptibility to some of their adverse effects. Acetaldehyde (the metabolite produced from ethanol by either ADH or MEOS) impairs hepatic oxygen utilization and forms protein adducts, resulting in antibody production, enzyme inactivation, and decreased DNA repair. It also stimulates collagen production by the vitamin A storing cells (lipocytes) and myofibroblasts, and causes glutathione depletion. Supplementation with S-adenosyl-L-methionine partly corrects the depletion and associated mitochondrial injury, whereas administration of polyunsaturated lecithin opposes the fibrosis. Thus, at the cellular level, the classic dichotomy between the nutritional and toxic effects of ethanol has now been bridged. The understanding of how the ensuing injury eventually results in irreversible scarring or cirrhosis may provide us with improved modalities for treatment and prevention.

Serum selenium concentration in liver cirrhotic patients suffering from hepatitis B and C in Pakistan

High rates of hepatitis B and C are present in Pakistan. Epidemiological surveys demonstrated an inverse association between selenium (Se) level and regional cancer incidence, as well as viral infection. In this cross-sectional descriptive analytical study, serum selenium concentration of 150 patients suffering from hepatitis B and C patients, along with 26 healthy controls, was determined by atomic absorption spectrophotometer equipped with hydride generation system. The mean and standard deviation of serum selenium concentration observed in male and female patients with hepatitis C were 101.60 ± 0.55 and 77.43 ± 0.47 μg/l, respectively, while the mean and standard deviation of serum selenium concentration observed in male and female patients with hepatitis B was 107.58 ± 0.44 and 137.8 ± 0.36 μg/l. Analysis of t test showed significant difference between hepatitis C and B (P < 0.001) patients in serum selenium concentration when compared with control.

The possible role of selenium concentration in hepatitis B and C patients

BACKGROUND/AIM

The compelling evidence reported that selenium is an essential trace mineral for human beings. Selenium plays a pivotal role in the restoration of immune functions. High rates of hepatitis B and C are present in Pakistan. Epidemiologic surveys demonstrated an inverse association between selenium (Se) level and regional cancer incidence, as well as viral infection. The present study was designed to evaluate the concentration of selenium in the serum of patients suffering from hepatitis B and C.

PATIENTS AND METHODS

In this cross-sectional descriptive analytical study, serum selenium concentration of 150 patients suffering from hepatitis B and C, along with 26 healthy controls, was determined by atomic absorption spectrophotometer equipped with hydride generation system, model Analytic Jena (Vario III).

RESULTS

The mean and standard deviation of serum selenium concentration observed in male and female patients with hepatitis C were 101.60 ± 0.55 and 77.43 ± 0.47 μ g/L, respectively, whereas the mean and standard deviation of serum selenium concentration observed in male and female patients with hepatitis B were 107.58 ± 0.44 and 137.8 ± 0.36 μg/L. Analysis of t test showed significant difference between C and B (P<0.001) patients in serum selenium concentration, when compared with the control.

CONCLUSION

The obtained results indicate that serum selenium concentration of hepatitis B and C patients is less than serum selenium concentration of healthy individuals. However, serum selenium decline is relative to severity of disease. Based on findings of this study, it is proposed that selenium should be supplemented in such patients in order to optimize nutritional support and to get better treatment response.

Role of nutrition in the management of hepatic encephalopathy in end-stage liver failure

Malnutrition is common in patients with end-stage liver failure and hepatic encephalopathy, and is considered a significant prognostic factor affecting quality of life, outcome, and survival. The liver plays a crucial role in the regulation of nutrition by trafficking the metabolism of nutrients, their distribution and appropriate use by the body. Nutritional consequences with the potential to cause nervous system dysfunction occur in liver failure, and many factors contribute to malnutrition in hepatic failure. Among them are inadequate dietary intake, malabsorption, increased protein losses, hypermetabolism, insulin resistance, gastrointestinal bleeding, ascites, inflammation/infection, and hyponatremia. Patients at risk of malnutrition are relatively difficult to identify since liver disease may interfere with biomarkers of malnutrition. The supplementation of the diet with amino acids, antioxidants, vitamins as well as probiotics in addition to meeting energy and protein requirements may improve nutritional status, liver function, and hepatic encephalopathy in patients with end-stage liver failure.

Nitric oxide and redox regulation in the liver: Part I. General considerations and redox biology in hepatitis

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are created in normal hepatocytes and are critical for normal physiologic processes, including oxidative respiration, growth, regeneration, apoptosis, and microsomal defense. When the levels of oxidation products exceed the capacity of normal antioxidant systems, oxidative stress occurs. This type of stress, in the form of ROS and RNS, can be damaging to all liver cells, including hepatocytes, Kupffer cells, stellate cells, and endothelial cells, through induction of inflammation, ischemia, fibrosis, necrosis, apoptosis, or through malignant transformation by damaging lipids, proteins, and/or DNA. In Part I of this review, we will discuss basic redox biology in the liver, including a review of ROS, RNS, and antioxidants, with a focus on nitric oxide as a common source of RNS. We will then review the evidence for oxidative stress as a mechanism of liver injury in hepatitis (alcoholic, viral, nonalcoholic). In Part II of this review, we will review oxidative stress in common pathophysiologic conditions, including ischemia/reperfusion injury, fibrosis, hepatocellular carcinoma, iron overload, Wilson's disease, sepsis, and acetaminophen overdose. Finally, biomarkers, proteomic, and antioxidant therapies will be discussed as areas for future therapeutic interventions.

A randomized trial of antioxidant therapy alone or with corticosteroids in acute alcoholic hepatitis

BACKGROUND/AIMS

Oxidative stress is putatively involved in the pathogenesis of alcohol-induced liver injury. This trial was devised to determine whether antioxidant therapy, alone or as an adjunct to corticosteroids, improved survival in patients with acute alcoholic hepatitis.

METHODS

Patients with a severe alcoholic hepatitis were stratified by sex and steroid use, and then randomized. The active group received N-acetylcysteine for one week, and vitamins A-E, biotin, selenium, zinc, manganese, copper, magnesium, folic acid and Coenzyme Q daily for 6 months. The trial was double blinded and placebo controlled. The primary end-point was mortality within 6 months.

RESULTS

Thirty-six (20 male, 16 female; mean discriminant function (DF) 86.6) received active drug, and 34 (18 male, 16 female; mean DF 76.4) received placebo. 180-day survival was not significantly different between patients receiving drug and placebo (52.8% vs. 55.8%, p=0.699). This was not affected by stratification for steroid use or sex. The only predictors of survival in multivariate analysis were initial bilirubin (p=0.017), white cell count (p=0.016) and age (p=0.037). Treatment allocation did not affect survival in multivariate analysis (p=0.830).

CONCLUSIONS

Antioxidant therapy, alone or in combination with corticosteroids, does not improve 6-month survival in severe alcoholic hepatitis.

Nutritional deficiencies in German middle-class male alcohol consumers: relation to dietary intake and severity of liver disease

OBJECTIVE

The purpose of the present study was to compare the nutrient intake and the nutritional status between German middle-class alcohol consumers and non-drinkers.

DESIGN

Cross-sectional study using patients with different stages of alcoholic liver disease (ALD) and healthy volunteers.

SETTING

Southern Germany.

SUBJECTS

Seventy-six hospitalized German middle-class alcohol consumers with different stages of alcoholic liver disease (ALD) and 22 healthy control subjects.

METHODS

Subjects and controls were nutritionally assessed and mineral and vitamin content was measured in blood and urine.

RESULTS

When compared with controls, alcohol consumers had significantly higher intakes of total calories, but intake of non-alcoholic calories did not differ between groups (P<0.05). Among drinkers, there was a decrease in percentage of energy derived from protein and fat and a significant increase in carbohydrates (P<0.05). With the exception of vitamin E, micronutrient intake of alcoholics was equal to that of controls; however, blood vitamin (vitamin C, retinol, lycopene, alpha- and gamma-carotene) and trace element (selenium, zinc) concentrations of alcohol-drinking patients were lower than those of non-drinkers.

CONCLUSION

From the results of this study it is concluded that in German middle-class male alcohol consumers the status of several micronutrients is disturbed, although dietary intake hardly differs from that in non-alcoholic controls.

Selenium concentrations in serum of individuals with liver diseases (cirrhosis or hepatitis): relationship with some nutritional and biochemical markers

Serum concentrations were measured in individuals (n = 50) with liver diseases (cirrhosis and hepatitis) by hydride generation atomic absorption spectrometry in a cross-sectional study. Mean serum selenium levels determined in patients with cirrhosis (n = 12) or with hepatitis (n = 38) were significantly lower (P<0.01) than those measured in control groups mainly due to a decreased liver function. Mean serum selenium concentrations were significantly lower in cirrhotic individuals when compared with patients with hepatitis (P<0.05). Therefore, the severity of the live injury is a factor conditioning the impairment in the selenium body status observed in individuals with hepatopathies. In hepatic patients serum total cholesterol levels showed a significant correlation with serum selenium concentrations (r=0.912, P<0.05) demonstrating the important role of selenium as an antioxidant agent; similarly, gamma-glutamic-transferase levels were significantly correlated with the serum selenium levels (r=-0.803, P<0.05) indicating that when the intensity of the hepatic injury increases (enhancement in serum GGT levels) concomitantly the serum selenium levels decrease significantly. No significant relationships between serum selenium levels and sex or age of patients were observed.

Serum selenium concentration in a representative sample of the Canarian population

The concentration of serum selenium in 395 individuals (187 males + 218 females) living in the Canary Islands, Spain was determined by hydride generation atomic absorption spectrometry. The mean selenium concentration was 74.7 +/- 25.2 microg/l ranging between 7.86 and 182.3 microg/l. Twenty-two adults (7.2% of the total) had serum selenium concentrations under 45 microg/l. It is widely accepted that below this selenium serum concentration (45 microg/l) there is an increased risk of cardiovascular disease and cancer. Our results fall within data recently published in other Spanish and European regions and are much lower than data observed in USA or seleniferous regions. The estimated Se intakes of our population were lower than the Recommended Dietary Allowances for American people. Individuals from Lanzarote had a mean Se concentration significantly higher than individuals from the other islands. This could be attributed to differences in Se content of soil and/or differences in dietary habits of the populations. Serum selenium concentration did not vary with the sex of the subjects. Individuals younger than 14 years old had a serum selenium concentration significantly lower than the rest of the individuals. No relationship with socio-economic status, educational level, smoking habits, physical exercise or beer consumption was found. However, individuals who consume wine more than three times a week showed higher selenium concentrations than individuals with lower consumption. Also, individuals with consumption above seven units of spirit drinks a week had the highest mean selenium concentration.

Nutritional and metabolic issues in cirrhosis and liver transplantation

In the last year some relevant papers on nutrition and metabolism in chronic liver disease and transplantation have been published. Studies investigating the reliability of predicting energy expenditure in cirrhosis, and some relevant contributions to the understanding of metabolic consequences of liver transplantation, deserve particular mention. These include the first direct evidence that liver transplantation corrects the insulin resistance present in cirrhosis, as well as studies on the role of genetic polymorphism of the vitamin D receptor gene in bone loss after transplantation. Other papers have dealt with body composition, polyunsaturated fatty acid and antioxidant status in cirrhosis. However, relevant contributions in the field of nutritional support in cirrhosis are surprisingly lacking.

Content of liver and brain ubiquinol-9 and ubiquinol-10 after chronic ethanol intake in rats subjected to two levels of dietary alpha-tocopherol

To assess the effect of chronic ethanol ingestion in the content of the reduced forms of coenzymes Q9 (ubiquinol-9) and Q10 (ubiquinol-10) as a factor contributing to oxidative stress in liver and brain, male Wistar rats were fed ad libitum a basal diet containing either 10 or 2.5 mg alpha-tocopherol/100 g diet (controls), or the same basal diet plus a 32% ethanol-25% sucrose solution. After three months treatment, ethanol chronically-treated rats showed identical growth rates to the isocalorically pair-fed controls, irrespectively of alpha-tocopherol dietary level. Lowering dietary alpha-tocopherol led to a decreased content of this vitamin in the liver and brain of control rats, without changes in that of ubiquinol-9, and increased levels of hepatic ubiquinol-10 and total glutathione (tGSH), accompanied by a decrease in brain tGSH. At the two levels of dietary alpha-tocopherol, ethanol treatment significantly decreased the content of hepatic alpha-tocopherol and ubiquinols 9 and 10. This effect was significantly greater at 10 mg alpha-tocopherol/100 g diet than at 2.5, whereas those of tGSH were significantly elevated by 43% and 9%, respectively. Chronic ethanol intake did not alter the content of brain alpha-tocopherol and tGSH, whereas those of ubiquinol-9 were significantly lowered by 20% and 14% in rats subjected to 10 and 2.5 mg alpha-tocopherol/100 g diet, respectively. It is concluded that chronic ethanol intake at two levels of dietary alpha-tocopherol induces a depletion of hepatic alpha-tocopherol and ubiquinols 9 and 10, thus contributing to ethanol-induced oxidative stress in the liver tissue. This effect of ethanol is dependent upon the dietary level of alpha-tocopherol, involves a compensatory enhancement in hepatic tGSH availability, and is not observed in the brain tissue, probably due to its limited capacity for ethanol biotransformation and glutathione synthesis.

Essentiality of selenium in the human body: relationship with different diseases

In the present review different aspects related to the essential element selenium in the human organism are considered. A large number of human studies have been performed in order to improve knowledge on the influence of this element in the origin and development of several degenerative diseases. Selenium deficiencies among human beings as well as animals are being recognized worldwide to be related to a number of pathologies. This element has also the special characteristic that the range between its essential and toxic character is very close, and consequently daily dietary intake should be appropriately monitored in individuals. Nevertheless, nowadays there is still a lot of controversy about the optimum dietary level of this element in order to cure or to prevent the appearance of diseases such as cirrhosis, cancer, diabetes, or cardiovascular pathologies. Results obtained in several animal and epidemiological studies have indicated that Se could constitute a dietary factor with protective action against several degenerative diseases.

Selenium, zinc and copper plasma levels in intrahepatic cholestasis of pregnancy, in normal pregnancies and in healthy individuals, in Chile

BACKGROUND/AIMS

Low blood Se levels have been previously shown in normal pregnancies (third trimester) and significantly lower levels in patients with intrahepatic cholestasis of pregnancy (ICP), in Finland and in Chile, suggesting that a low or marginal dietary availability of Se may contribute to the pathogenesis of this disease. The aim of this study was to investigate whether a temporal change in plasma concentration of Se, and seasonal fluctuations in plasma concentrations of Se, Zn and Cu, could coincide with changes in the prevalence of ICP.

METHODS

A cross-sectional cohort study was done including 21 ICP patients, 98 women in the third trimester of a normal pregnancy, 29 non-pregnant women, and also 13 individuals (seven non-pregnant women and six men) who had been studied 9 years before. Plasma Se, Zn and Cu were measured by atomic spectroscopy. Plasma Se levels in the present study were compared to the results obtained 5 to 7 years before, employing identical methodology in similar population samples.

RESULTS

Plasma Se concentrations in non-pregnant women were higher than in the previous study: 1.43+/-0.34 micromol/l vs 0.85+/-0.13; p<0.001. In comparison to non-pregnant women, normal pregnancies near term had lower plasma levels of Se: 1.08+/-0.25 micromol/l; p<0.01, and Zn: 17.90+/-3.61 micromol/l vs 19.71+/-3.21; p<0.05, but higher plasma levels of Cu: 34.35+/-7.12 micromol/l vs 20.62+/-3.34; p<0.01. In normal pregnancies, plasma Se concentration was significantly higher in summer (1.34+/-0.19 micromol/l) than in the other seasons, while Zn and Cu diminished. Similar to previous studies, ICP patients had significantly lower Se plasma levels than normal pregnancies: 0.94+/-0.12 micromol/l, p<0.05, and Cu levels were significantly higher: 50.80+/-7.02 micromol/l, p<0.01. Cu plasma levels correlated with the biochemical severity of the disease. Zn did not change in ICP.

CONCLUSIONS

The present study shows that the decrease in the prevalence of ICP in Chile during the last decade coincides with an increase in plasma Se levels. Its lower incidence during summer coincides with a higher plasma Se concentration in summer than in other seasons, as observed in normal pregnancies.

[The impact of alcohol and chronic liver disease of micronutrients metabolism]

Liver disease, alcohol and malnutrition are combinations usually associated with micronutrient impairment. Chronic liver disease courses with lower storage and activation of vitamin-coenzymes related to their malabsorption. Alcohol worsens the picture by reducing food intake, increasing micronutrients utilization and decreasing their absorption secondary to either intestinal or pancreatic injuries. Other concurrent causes would be drug treatments, urinary losses, protein deficiency and oxidative stress. As consequences the clinical signs are anemia, liver steatosis, oxidative stress and immunosuppression.

Nutritional issues in cirrhosis and liver transplantation

In the past year, some relevant papers on the mechanisms of malnutrition in cirrhosis have been published. Studies investigating the metabolic destiny of leucine after protein breakdown, which have contributed to a better understanding of the pathogenesis of muscle wasting and fat depletion in these patients, deserve particular mention. Also, the demonstration that chronically reducing hyperinsulinaemia in cirrhosis is able to improve insulin sensitivity opens novel pathogenic and therapeutic perspectives for such a metabolic derangement in these patients. Other papers dealt with unsaturated lipids, lipoperoxidation and antioxidants in chronic liver disease. However, randomized trials on parenteral or enteral nutrition in cirrhosis and liver transplantation are missing.

Plasma selenium in patients with cirrhosis

Plasma selenium concentration is decreased in patients with cirrhosis and, based on this finding, it has been suggested that patients with cirrhosis are selenium deficient. We measured plasma selenium concentration and the two plasma selenoproteins, glutathione peroxidase (GSHPx-3) and selenoprotein P, in the plasma of patients with cirrhosis of Child classes A, B, and C and in control subjects. Plasma selenium declined in proportion to the severity of the cirrhotic condition, as indicated by the Child class. Selenoprotein P, which originates largely in the liver, declined in a similar manner. Plasma glutathione peroxidase activity increased, and GSHPx-3 originates in the kidney. Selenium in the non-selenoprotein pool, shown by others to be largely selenomethionine in albumin, declined. Thus, although plasma selenium is decreased in patients with cirrhosis, the increase in plasma glutathione peroxidase activity, which occurs in them, suggests that patients with cirrhosis do not have selenium deficiency.

Blood selenium and glutathione peroxidase status in patients with colorectal cancer

PURPOSE

It is still controversial whether a low selenium level and a reduced activity of the selenium-dependent enzyme, glutathione peroxidase, in blood are associated with an increased risk and poor prognosis of cancer in humans. This study evaluates whether colorectal cancer patients have lower serum selenium and glutathione peroxidase levels than a gender-matched and age-matched control group and whether there is a correlation to clinical data and prognosis.

METHODS

In a retrospective study, serum selenium and glutathione peroxidase activity of 106 patients with colorectal cancer were determined. Clinical data were provided by our long-term follow-up program for colorectal cancer patients.

RESULTS

Patients with a selenium level <70 microg/l had a significantly lower mean survival time and a lower cumulative cancer-related survival rate than patients with a selenium level >70 microg/l (P = 0.0009). When considering the different tumor stages, a decline of the mean selenium level in the T4 carcinoma group was found in the analysis of variance (P < 0.05). The lowest selenium level was found for patients with advanced tumor disease and in a preoperative situation, ie., high tumor burden. In comparison with the control group, the cancer group showed a significant reduction of serum glutathione peroxidase activity (P < 0.01) but no significant difference in selenium level.

CONCLUSIONS

These results support the hypothesis of an association between low selenium level and advanced tumor disease. From our data, it cannot be decided whether this phenomenon is more likely to be a consequence or a causative factor for development and course of the disease.

Pathogenesis of alcoholic liver disease with particular emphasis on oxidative stress

Oxidative stress is well recognized to be a key step in the pathogenesis of ethanol-associated liver injury. Ethanol administration induces an increase in lipid peroxidation either by enhancing the production of oxygen reactive species and/or by decreasing the level of endogenous antioxidants. Numerous experimental studies have emphasized the role of the ethanol-inducible cytochrome P450 in the microsomes and the molybdo-flavoenzyme xanthine oxidase in the cytosol. This review shows the putative role of ethanol-induced disturbances in iron metabolism in relation to iron as a pro-oxidant factor. Ethanol administration also affects the mitochondrial free radical generation. Many previous studies suggest a role for active oxygens in ethanol-induced mitochondrial dysfunction in hepatocytes. Recent studies in our laboratory in the Department of Internal Medicine, Keio University, using a confocal laser scanning microscopic system strongly suggest that active oxidants generated during ethanol metabolism produce mitochondrial membrane permeability transition in isolated and cultured hepatocytes. In addition, acetaldehyde, ethanol consumption-associated endotoxaemia and subsequent release of inflammatory mediators may cause hepatocyte injury via both oxyradical-dependent and -independent mechanisms. These cytotoxic processes may lead to lethal hepatocyte injury. Investigations further implicate the endogenous glutathione-glutathione peroxidase system and catalase as important antioxidants and cytoprotective machinery in the hepatocytes exposed to ethanol.

Low selenium status in alcoholic cirrhosis is correlated with aminopyrine breath test. Preliminary effects of selenium supplementation

The relationship among impaired selenium status, lipid peroxidation, and liver function was examined in 19 hospitalized patients with severe alcoholic cirrhosis. Plasma selenium was found to be significantly lower (mean +/- SD: 54 +/- 13 micrograms/L) than in healthy controls (83 +/- 11 micrograms/L) and plasma malondialdehyde, assessed as thiobarbituric acid reactants, which reflects lipid peroxidation, was increased (2.0 +/- 1.2 mumol/L vs < 1.2 mumol/L in controls). The mean 14C aminopyrine breath test, an indicator of liver function, was lower than normal (2.7 +/- 1.9 vs 6.3 +/- 0.9% in controls) and found to be significantly correlated with plasma selenium (r = 0.59, p < 0.05). A prospective, randomized selenium supplementation trial was conducted in a group of 16 patients who received either daily 100 micrograms selenium as enriched yeast during 4 mo or a placebo. Among the 10 patients who completed the study, plasma selenium significantly increased in the supplemented group (n = 4; before: 58 +/- 10 micrograms/L, and after 101 +/- 12 micrograms/L, p < 0.01) contrary to the placebo group (n = 6, before: 47 +/- 10 micrograms/L, after: 57 +/- 9 micrograms/L, n.s.). 14C aminopyrine breath test improved in three out of four selenium-supplemented patients and in three out of six placebo patients, but the small number of patients did not allow statistical evaluation. These results demonstrate that low selenium status in alcoholic cirrhosis is correlated to liver function and could be improved by supplementation.

Selenium deficiency in HIV infection and the acquired immunodeficiency syndrome (AIDS)

Selenium is required for activity of the enzyme glutathione peroxidase, and selenium deficiency may be associated with myopathy, cardiomyopathy and immune dysfunction including oral candidiasis, impaired phagocytic function and decreased CD4 T-cells. We assessed selenium status in 12 patients with AIDS compared to normals and found significantly low plasma and red blood cell levels. Plasma selenium in AIDS was 0.043 +/- 0.01 microgram/ml vs 0.095 +/- 0.016 in controls (P < 0.001). Selenium status correlated with serum albumin (r = 0.77; P < 0.001) and 60% had documented GI malabsorption as determined by abnormal D-Xylose tests. In a subsequent study blood selenium and glutathione peroxidase were diminished in 12 AIDS and 8 ARC patients compared with normals (all P < 0.001). For glutathione peroxidase the mean levels were decreased by 45% in AIDS and 27% in ARC versus controls (P < 0.001). Both plasma selenium and glutathione peroxidase significantly correlated with total lymphocyte counts (r = 0.65; P < 0.001; glutathione peroxidase and lymphocyte counts). This occurred in both homosexuals and drug users with AIDS and irrespective of the presence or absence of diarrhea or GI malabsorption. To determine if tissue levels of selenium were also depleted we studied cardiac selenium levels in autopsy AIDS hearts compared to age and sex matched controls. Cardiac selenium in AIDS was 0.327 +/- 0.082 micrograms/g dry weight versus 0.534 +/- 0.184 in controls (P < 0.01). Two cases had histologic cardiomyopathy pathologically consistent with the cardiomyopathy described in Keshan disease associated with low selenium blood levels. To further assess mechanisms of nutrient and selenium deficiency in AIDS we studied dietary intake in outpatients and inpatients with various stages of HIV infection. Inadequate selenium intake based on a computer (Nutritionist 3) analysis of 72 h diet records was present in only 17% of clinically stable HIV positive outpatients and 71% of inpatients with AIDS.

CONCLUSIONS

Selenium deficiency is common in HIV positive patients as documented by low plasma and red blood cell levels of selenium, diminished activity of glutathione peroxidase, and low cardiac selenium levels in AIDS hearts. Patients with AIDS tend to have more severe deficits than those with earlier stages of HIV infection. The selenium deficit in blood does correlate with serum albumin levels and total lymphocyte counts. Poor dietary intake and malabsorption could lead to this condition which has important implications for both cardiac and immune functions in HIV positive patients.

Hypothalamic-pituitary-thyroid axis in chronic alcoholism. II. Deiodinase activities and thyroid hormone concentrations in brain and peripheral tissues of rats chronically exposed to ethanol

Thyroxine (T4), triiodothyronine (T3) concentrations, and the activities of the three deiodinase isoenzymes were measured in different brain regions and peripheral tissues of rats. According to an animal model of alcohol addiction, "behaviorally" dependent rats having lost control over their intake of ethanol were compared with alcohol-naive controls and ethanol-experienced, but "controlled" consumers. The two kinds of alcohol-experienced rats were investigated either 24 hr or 3 months after ethanol withdrawal. The results of these four groups were compared with those of an ethanol-naive control group. During withdrawal, the activities of type II 5'-deiodinase (which catalyzes deiodination of T4 and T3 in the CNS) in both the "behaviorally dependent" rats and the "controlled drinkers" were significantly lower than in the alcohol-naive controls in the frontal cortex, parieto-occipital cortex, hippocampus, and striatum, but not in the cerebellum or pituitary. Probably as a result, the tissue concentrations of T4 were higher in areas of the CNS in the groups exposed to alcohol. However, the T3 concentrations were normal. No relevant differences were seen between the activities of type III 5-deiodinase (which catalyzes the further deiodination of T3) observed in these groups. After 3 months of abstinence, the type II 5'-deiodinase activities had almost returned to normal in both "controlled drinkers" and "behaviorally dependent" animals, whereas type III 5-deiodinase activity was inhibited, possibly to maintain physiological concentrations of T3 during abstinence. Indeed, the tissue levels of T3 were normal in the areas of the CNS, and the T4 levels were still elevated. However, the liver concentrations of T3 and T4 were significantly lower in the "behaviourally dependent" animals than in the "controlled" drinkers after 3 months of abstinence, whereas no differences were found between the T4 and T3 concentrations in the areas of the CNS investigated in the two groups exposed to ethanol. These results suggest that chronic administration of ethanol affects intracellular thyroid hormone metabolism in both rat CNS and liver in the highly complex manner. No direct evidence of ethanol-induced enhancement of tissue uptake or concentrations was obtained. However, taking into account the numerous similarities between the clinical picture of hyperthyroidism and the symptomatology of alcoholism, it may be hypothesized that ethanol may directly influence any step in the as yet unknown biochemical cascade of thyroid hormone function.

Alcohol and the liver: 1994 update

This article reviews current concepts on the pathogenesis and treatment of alcoholic liver disease. It has been known that the hepatotoxicity of ethanol results from alcohol dehydrogenase-mediated excessive generation of hepatic nicotinamide adenine dinucleotide, reduced form, and acetaldehyde. It is now recognized that acetaldehyde is also produced by an accessory (but inducible) microsomal pathway that additionally generates oxygen radicals and activates many xenobiotics to toxic metabolites, thereby explaining the increased vulnerability of heavy drinkers to industrial solvents, anesthetics, commonly used drugs, over-the-counter medications, and carcinogens. The contribution of gastric alcohol dehydrogenase to the first-pass metabolism of ethanol and alcohol-drug interactions is discussed. Roles for hepatitis C, cytokines, sex, genetics, and age are now emerging. Alcohol also alters the degradation of key nutrients, thereby promoting deficiencies as well as toxic interactions with vitamin A and beta carotene. Conversely, nutritional deficits may affect the toxicity of ethanol and acetaldehyde, as illustrated by the depletion in glutathione, ameliorated by S-adenosyl-L-methionine. Other "supernutrients" include polyunsaturated lecithin, shown to correct the alcohol-induced hepatic phosphatidylcholine depletion and to prevent alcoholic cirrhosis in nonhuman primates. Thus, a better understanding of the pathology induced by ethanol is now generating improved prospects for therapy.

Mechanisms of ethanol-drug-nutrition interactions

Mechanisms of the toxicologic manifestations of ethanol abuse are reviewed. Hepatotoxicity of ethanol results from alcohol dehydrogenase-mediated excessive hepatic generation of nicotinamide adenine dinucleotide and acetaldehyde. It is now recognized that acetaldehyde is also produced by an accessory (but inducible) pathway, the microsomal ethanol-oxidizing system, which involves a specific cytochrome P450. It generates oxygen radicals and activates many xenobiotics to toxic metabolites, thereby explaining the increased vulnerability of heavy drinkers to industrial solvents, anesthetics, commonly used drugs, over-the-counter medications and carcinogens. The contribution of gastric alcohol dehydrogenase to the first pass metabolism of ethanol and alcohol-drug interactions is now recognized. Alcohol also alters the degradation of key nutrients, thereby promoting deficiencies as well as toxic interactions with vitamin A and beta-carotene. Conversely, nutritional deficits may affect the toxicity of ethanol and acetaldehyde, as illustrated by the depletion in glutathione, ameliorated by S-adenosyl-L-methionine. Other supernutrients include polyenylphosphatidylcholine, shown to correct the alcohol-induced hepatic phosphatidylcholine depletion and to prevent alcoholic cirrhosis in non-human primates. Thus, a better understanding of the pathology induced by ethanol has now generated improved prospects for therapy.

Effects of chronic alcohol feeding and murine AIDS virus infection on liver antioxidant defense systems in mice

Whether ethanol (ETOH) abuse could contribute to the development of acquired immunodeficiency syndrome (AIDS) among human immunodeficiency virus (HIV)-positive drug abusers is a critical question for which little experimental information is available. This study was designed to determine if chronic ETOH feeding and murine AIDS virus infection cooperatively affected liver antioxidant defense systems in C57B1/6 female mice. Mice were divided into two groups and fed the Lieber-DeCarli liquid ETOH diet containing ETOH at a concentration to provide 31% of total caloric intake or an isocaloric liquid control (control) diet in which dextrin-maltose replaced ETOH. One week after the initiation of ETOH feeding, half of the mice in each diet group (8 mice) were injected intraperitoneally with murine retrovirus (MAIDS) stock. After 3 and 5 weeks of ETOH feeding, half of the mice in each of the four treatment groups (4 mice) were killed, and livers were excised for biochemical analysis. Liver reduced glutathione (GSH) levels and activities of glutathione peroxidase (GP), glutathione reductase (GR), glutathione transferase (GT), catalase and superoxide dismutase (SOD), and serum ETOH concentrations were determined. The results demonstrated that serum ETOH concentrations were significantly elevated in ETOH-MAIDS group when compared with the ETOH group. Moreover, chronic ETOH feeding and MAIDS infection independently depressed liver antioxidant defense capability, and together led to an additive inhibition of GSH and SOD activities. In addition, MAIDS infection inhibited an ETOH-induced increase in catalase and GT activities. These results suggest that alcohol abuse could contribute to the development of AIDS by inhibiting the protective capability of an infected individual against oxidative stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum selenium in adult Czechoslovak (central Bohemia) population

The serum selenium levels in 367 healthy adult (25-64 yr) Central Bohemia residents, 176 men and 191 women, were determined using atomic absorption spectrometry. An extremely wide range of values was found in the whole population sample (< 20-296 micrograms/L) as well as in each sex or age category studied. The mean selenium concentration and 95% confidence interval calculated after logarithmic transformation of the data were 74 micrograms/L (71-77) for the whole population sample, 72 micrograms/L (67-76) for men, and 76 micrograms/L (72-81) for women. About 10% of the residents exhibited serum selenium level below 45 micrograms/L. There was no significant correlation between serum selenium and sex, age, or smoking status of participants. However, the lowest average level was found in the group of heavy smoking women: 66 micrograms/L. The selenium status of the Central Bohemia population seems to be below European average. Groups of residents having a very low nutritional selenium intake may be expected to occur in this population.

Selenium in chronic liver disease

In order to assess the role of selenium (Se) in chronic liver disease, we have measured serum, urinary and hepatic selenium in a range of liver diseases and correlated them with nutritional status and conventional liver biochemistry. Serum Se levels (microgram/l +/- S.D.) were significantly lower in both alcoholic (63.6 +/- 18.2, p less than 0.0001) and non-alcoholic liver disease (NALD) (60.6 +/- 13.6, p less than 0.0001) compared to healthy controls (87.8 +/- 21.2) and non-malignant 'disease controls' (80.3 +/- 19.1). Hepatic Se levels (microgram/g of dry weight) were also reduced in both ALD (0.568 +/- 0.647, p less than 0.005) and NALD (0.863 +/- 0.308, p less than 0.005) compared to controls (1.227 +/- 0.296), 24-h urinary Se excretion (microgram) in ALD (24.6 +/- 10.7) and NALD (29.0 +/- 14.3) was similar to controls (30.3 +/- 8.7). Serum Se showed a highly significant positive correlation with albumin (p less than 0.001) in both ALD and NALD. Serum levels were also significantly correlated with anthropometric measurements. Dietary assessment of patients with primary biliary cirrhosis and low serum Se levels did not show a reduced dietary intake. Our data show that Se levels are low in liver disease irrespective of aetiology and suggest that these low levels are more likely to be related to overall nutritional status than to dietary intake.

Implication of free radical mechanisms in ethanol-induced cellular injury

Numerous experimental data reviewed in the present article indicate that free radical mechanisms contribute to ethanol-induced liver injury. Increased generation of oxygen- and ethanol-derived free radicals has been observed at the microsomal level, especially through the intervention of the ethanol-inducible cytochrome P450 isoform (CYP2E1). Furthermore, an ethanol-linked enhancement in free radical generation can occur through the cytosolic xanthine and/or aldehyde oxidases, as well as through the mitochondrial respiratory chain. Ethanol administration also elicits hepatic disturbances in the availability of non-safely-sequestered iron derivatives and in the antioxidant defense. The resulting oxidative stress leads, in some experimental conditions, to enhanced lipid peroxidation and can also affect other important cellular components, such as proteins or DNA. The reported production of a chemoattractant for human neutrophils may be of special importance in the pathogenesis of alcoholic hepatitis. Free radical mechanisms also appear to be implicated in the toxicity of ethanol on various extrahepatic tissues. Most of the experimental data available concern the gastric mucosa, the central nervous system, the heart, and the testes. Clinical studies have not yet demonstrated the role of free radical mechanisms in the pathogenesis of ethanol-induced cellular injury in alcoholics. However, many data support the involvement of such mechanisms and suggest that dietary and/or pharmacological agents able to prevent an ethanol-induced oxidative stress may reduce the incidence of ethanol toxicity in humans.

Antioxidant status (selenium, vitamins A and E) and aging

Antioxidant status can be evaluated by blood selenium, vitamins A and E. The level of selenium was determined in whole blood, erythrocytes and plasma of 170 French people (70-95 years old) healthy and with intercurrent illness, by using PIXE (proton-induced X-ray emission analysis). These results are discussed with other values from the literature. Plasma levels of vitamins A and E have been measured by HPLC. All data were compared with those obtained for younger subjects. Healthy elderly people residing in a geriatric home received selenium supplements during 1 month. The influence of this supplementation brought to light a deficiency for this trace element. The correlation of aging and nutritional requirements with immune function, heart and cancer death rate is presented and discussed.

Alcohol, liver, and nutrition

Until two decades ago, dietary deficiencies were considered to be the major reason why alcoholics developed liver disease. As the overall nutrition of the population improved, more emphasis was placed on secondary malnutrition. Direct hepatotoxic effects of ethanol were also established, some of which were linked to redox changes produced by reduced nicotinamide adenine dinucleotide (NADH) generated via the alcohol dehydrogenase (ADH) pathway. It was also determined that ethanol can be oxidized by a microsomal ethanol oxidizing system (MEOS) involving cytochrome P-450: the newly discovered ethanol-inducible cytochrome P-450 (P-450IIE1) contributes to ethanol metabolism, tolerance, energy wastage (with associated weight loss), and the selective hepatic perivenular toxicity of various xenobiotics. P-450 induction also explains depletion (and enhanced toxicity) of nutritional factors such as vitamin A. Even at the early fatty-liver stage, alcoholics commonly have a very low hepatic concentration of vitamin A. Ethanol administration in animals was found to depress hepatic levels of vitamin A, even when administered with diets containing large amounts of the vitamin, reflecting, in part, accelerated microsomal degradation through newly discovered microsomal pathways of retinol metabolism, inducible by either ethanol or drug administration. The hepatic depletion of vitamin A was strikingly exacerbated when ethanol and other drugs were given together, mimicking a common clinical occurrence. Hepatic retinoid depletion was found to be associated with lysosomal lesions and decreased detoxification of chemical carcinogens. To alleviate these adverse effects, as well as to correct problems of night blindness and sexual inadequacies, the alcoholic patient should be provided with vitamin A supplementation. Such therapy, however, is complicated by the fact that in excessive amounts vitamin A is hepatotoxic, an effect exacerbated by long-term ethanol consumption. This results in striking morphologic and functional alterations of the mitochondria with leakage of mitochondrial enzymes, hepatic necrosis, and fibrosis. Thus, treatment with vitamin A and other nutritional factors (such as proteins) is beneficial but must take into account a narrowed therapeutic window in alcoholics who have increased needs for such nutrients, but also display an enhanced susceptibility to their adverse effects. Massive doses of choline also exerted some toxic effects and failed to prevent the development of alcoholic cirrhosis. Acetaldehyde (the metabolite produced from ethanol by either ADH or MEOS) impairs hepatic oxygen utilization and forms protein adducts, resulting in antibody production, enzyme inactivation, and decreased DNA repair. It also enhances pyridoxine and perhaps folate degradation and stimulates collagen production by the vitamin A storing cells (lipocytes) and myofibroblasts.(ABSTRACT TRUNCATED AT 400 WORDS)

Hepatic, metabolic and toxic effects of ethanol: 1991 update

Until two decades ago, dietary deficiencies were considered to be the only reason for alcoholics to develop liver disease. As the overall nutrition of the population improved, more emphasis was placed on secondary malnutrition and direct hepatotoxic effects of ethanol were established. Ethanol is hepatotoxic through redox changes produced by the NADH generated in its oxidation via the alcohol dehydrogenase pathway, which in turn affects the metabolism of lipids, carbohydrates, proteins, and purines. Ethanol is also oxidized in liver microsomes by an ethanol-inducible cytochrome P-450 (P-450IIE1) that contributes to ethanol metabolism and tolerance, and activates xenobiotics to toxic radicals thereby explaining increased vulnerability of the heavy drinker to industrial solvents, anesthetic agents, commonly prescribed drugs, over-the-counter analgesics, chemical carcinogens, and even nutritional factors such as vitamin A. In addition, ethanol depresses hepatic levels of vitamin A, even when administered with diets containing large amounts of the vitamin, reflecting, in part, accelerated microsomal degradation through newly discovered microsomal pathways of retinol metabolism, inducible by either ethanol or drug administration. The hepatic depletion of vitamin A is strikingly exacerbated when ethanol and other drugs were given together, mimicking a common clinical occurrence. Microsomal induction also results in increased production of acetaldehyde. Acetaldehyde, in turn, causes injury through the formation of protein adducts, resulting in antibody production, enzyme inactivation, decreased DNA repair, and alterations in microtubules, plasma membranes and mitochondria with a striking impairment of oxygen utilization. Acetaldehyde also causes glutathione depletion and lipid peroxidation, and stimulates hepatic collagen production by the vitamin A storing cells (lipocytes) and myofibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic ethanol consumption on selenium status and utilization in rats

Effects of chronic ingestion of 2 levels of alcohol on selenium (Se) utilization were determined in initially Se-depleted rats. Male weanling rats were fed ad lib a Se deficient (0.012 mg/kg) basal diet for 4 weeks and then were meal-fed low or marginally adequate Se in the form of high Se yeast for 4 weeks. During Se repletion, ethanol, which replaced medium-chain triglycerides in the diet, provided 10 or 20 percent of food energy. The basal diet provided 80% of food energy as well as adequate protein, vitamins and minerals. In rats given adequate Se moderate chronic ethanol consumption did not influence Se absorption or retention, but increasing ethanol level raised Se in liver and whole blood in a linear fashion and in kidney in a quadratic manner. In this rat model measures of Se status were reduced by low Se intake, not chronic moderate ethanol ingestion.

Physiological and nutritional importance of selenium

The essential trace element selenium has recently attracted attention because of its potentialities in the maintenance of human health. Selenium forms part of the active site of the peroxide-destroying enzyme glutathione peroxidase, and it also has other functions, for example in biotransformation, detoxification and the immune response. Functional and clinical consequences of selenium deficiency states have been described, and the selenium requirement, which is influenced by the usual selenium exposure, has been discussed. Wide variations have been found in selenium status in different parts of the world, and populations or groups of patients exposed to marginal deficiency are more numerous than was previously thought. Current research activities in the field of human medicine and nutrition are devoted to the possibilities of using selenium for the prevention or treatment of degenerative or free radical diseases such as neurological disorders, inflammatory diseases or cancer. Pharmacological selenium doses are also recommended as an adjuvant in some treatments.

Determination of selenium in blood components by X-ray emission spectrometry. Procedures, concentration levels, and health implications

Sampling, storing, sample pretreatment, and experimental conditions for selenium (Se) determination in human serum, plasma, and whole blood by X-ray emission spectrometric (XRS) methods are described. Concentration levels in these biological fluids, found by this technique, are discussed and compared to values found by other techniques for the same healthy population group in the same area. XRS analysis of blood from patients with various pathological conditions is reviewed, with special attention to the relation of Se with the concentration level of other essential or nonessential trace elements.

Mechanism of ethanol induced hepatic injury

Ethanol is hepatotoxic through redox changes produced by the NADH generated in its oxidation via the alcohol dehydrogenase pathway, which in turn affects the metabolism of lipids, carbohydrates, proteins and purines. Ethanol is also oxidized in liver microsomes by an ethanol-inducible cytochrome P-450 (P-450IIE1) which contributes to ethanol metabolism and tolerance, and activates xenobiotics to toxic radicals thereby explaining increased vulnerability of the heavy drinker to industrial solvents, anesthetic agents, commonly prescribed drugs, over-the-counter analgesics, chemical carcinogens and even nutritional factors such as vitamin A. Induction also results in energy wastage and increased production of acetaldehyde. Acetaldehyde, in turn, causes injury through the formation of protein adducts, resulting in antibody production, enzyme inactivation, decreased DNA repair, and alterations in microtubules, plasma membranes and mitochondria with a striking impairment of oxygen utilization. Acetaldehyde also causes glutathione depletion and lipid peroxidation, and stimulates hepatic collagen synthesis, thereby promoting fibrosis.

Lipid peroxidation and antioxidant defense systems in rat liver after chronic ethanol feeding

The effects of chronic ethanol feeding on hepatic lipid peroxidation, ascorbic acid, glutathione and vitamin E levels were investigated in rats fed low or adequate amounts of dietary vitamin E. Hepatic lipid peroxidation was significantly increased after chronic ethanol feeding in rats receiving a low-vitamin E diet, indicating that dietary vitamin E is an important determinant of hepatic lipid peroxidation induced by chronic ethanol feeding. No significant change was observed in hepatic non-heme iron content, but hepatic content of ascorbic acid and glutathione was increased by ethanol feeding. Both low dietary vitamin E and ethanol feeding significantly reduced hepatic alpha-tocopherol content, and the lowest hepatic alpha-tocopherol was found in rats receiving a combination of low vitamin E and ethanol. Plasma alpha-tocopherol was elevated after ethanol feeding, probably because of the associated hyperlipemia. Both the ratio of plasma alpha-tocopherol/plasma lipid and the red blood cell alpha-tocopherol were reduced by ethanol feeding. Furthermore, ethanol feeding caused a marked increase of hepatic alpha-tocopheryl quinone, a metabolite of alpha-tocopherol by free radical reactions. Ethanol feeding caused little changes of alpha-tocopherol and alpha-tocopheryl quinone content in mitochondria, whereas a striking increase in alpha-tocopheryl quinone was observed in microsomes. These data suggest that ethanol feeding causes a marked alteration of vitamin E metabolism in the liver and that the combination of ethanol with a low-vitamin E intake results in a decrease of hepatic alpha-tocopherol content which renders the liver more susceptible to free radical attack.

Reduced cardiac selenium content in the acquired immunodeficiency syndrome

Selenium deficiency has been implicated in the pathogenesis of a dilated congestive cardiomyopathy in areas of China (Keshan disease) and in several patients on long-term total parenteral nutrition. Recently a clinically and pathologically similar cardiomyopathy has been described in AIDS. Since blood selenium levels are low in AIDS, we assayed cardiac selenium status by a spectrofluorometric method in eight AIDS patients at autopsy compared to nine age-matched, non-AIDS autopsy controls with histologically normal hearts. We found (mean +/- SD) a cardiac selenium level of 0.327 +/- 0.082 microgram/g dry weight in AIDS vs 0.534 +/- 0.184 microgram/g dry weight in controls (p less than 0.01; Student's t test). There were no significant differences between the groups for heart weight, serum CPK, or other laboratory parameters. No specific chest x-ray or electrocardiographic abnormalities were present. Histologically, all AIDS hearts were abnormal; mostly with mild degrees of muscle hypertrophy or fibrosis. Foci of myocytolysis and myocyte necrosis and fibrous replacement of myocytes and monocytic infiltration were present in two AIDS cases. We conclude that heart tissue in AIDS demonstrates a significant selenium deficit. These data provide a potential link between selenium deficiency and cardiomyopathy in AIDS.

Decreased hepatic selenium content in alcoholic cirrhosis

Selenium deficiency has been implicated as contributing to hepatic injury in alcoholics. The mechanism by which this occurs is most likely lipoperoxidation secondary to decreased activity of the selenoenzyme glutathione peroxidase. To further assess this relationship, we measured selenium content in autopsy livers in 12 patients with alcoholic cirrhosis compared to 13 patients matched for age and sex dying from other causes, mostly with cardiopulmonary diseases. The mean (+/- SEM) hepatic selenium content in cirrhosis was 0.731 +/- 0.077 microgram/g dry weight versus 1.309 +/- 0.166 microgram/g in controls (P less than 0.005; Student's t test). Clinical and biochemical indices of significant hepatic dysfunction, including encephalopathy, ascites, and elevations of serum bilirubin or prothrombin time, were only present in the cirrhotic group. A significant inverse correlation between hepatic selenium content and the prothrombin time was noted (r = -0.50; P less than 0.02). No significant relationships between hepatic selenium and the abnormalities of bilirubin, albumin, or aspartate aminotransferase were found. We conclude that significantly decreased hepatic selenium stores are present in patients with severe alcoholic cirrhosis compared to controls. The magnitude of that selenium deficit does correlate with some indices of hepatic function, specifically the prothrombin time. These data lend further support to a true selenium deficiency state in alcoholic cirrhosis. It is highly possible that selenium deficiency represents an important link, synergistically joining the nutritional and hepatotoxic backgrounds of alcoholic liver injury and cirrhosis.

Diminished blood selenium levels in renal failure patients on dialysis: correlations with nutritional status

Selenium deficiency has been implicated as contributing to the development of cardiovascular disease, skeletal muscle myopathy, anemia, increased cancer risk, and deranged immune function. Since these problems may also be associated with renal failure, and the kidney plays an important role in selenium homeostasis, we measured selenium and compared it with nutritional status in 24 stable hemodialysis patients, 12 chronic intermittent peritoneal dialysis patients, and 29 healthy controls. Whole blood and plasma selenium was determined by a spectrofluorometric method. For whole blood the mean (+/- SD) selenium levels were 0.11 +/- 0.02 micrograms/ml in controls vs. 0.071 +/- 0.01 micrograms/ml in hemodialysis cases and 0.052 +/- 0.006 micrograms/ml in peritoneal dialysis (p less than 0.005). Significant decreases were seen also for plasma and red blood cell selenium in all groups respectively. Pre- and postdialysis plasma and whole blood selenium levels showed no significant changes in both dialysis groups. However, predialysis residual peritoneal fluid did contain selenium (0.029 +/- 0.005 micrograms/ml). Some evidence of protein-energy undernutrition was noted in both dialysis groups compared with controls. However, no significant differences in nutritional parameters were noted between hemodialysis and peritoneal dialysis patients. When all groups were combined, significant correlations were found between whole blood selenium and serum albumin (r = 0.61; p less than 0.001), triceps skin fold in females (r = 0.62; p less than 0.001), and midarm muscle circumference in males (r = 0.71; p less than 0.001). We conclude that low blood selenium is present in renal failure patients undergoing hemodialysis. This abnormality is even greater in peritoneal dialysis cases.(ABSTRACT TRUNCATED AT 250 WORDS)