Micronutrient status in relationship to mortality in HIV-1 disease

Review on the health-promoting effect of adequate selenium status

Selenium is an essential microelement involved in various biological processes. Selenium deficiency increases the risk of human immunodeficiency virus infection, cancer, cardiovascular disease, and inflammatory bowel disease. Selenium possesses anti-oxidant, anti-cancer, immunomodulatory, hypoglycemic, and intestinal microbiota-regulating properties. The non-linear dose-response relationship between selenium status and health effects is U-shaped; individuals with low baseline selenium levels may benefit from supplementation, whereas those with acceptable or high selenium levels may face possible health hazards. Selenium supplementation is beneficial in various populations and conditions; however, given its small safety window, the safety of selenium supplementation is still a subject of debate. This review summarizes the current understanding of the health-promoting effects of selenium on the human body, the dietary reference intake, and evidence of the association between selenium deficiency and disease.

Selenocompounds and Sepsis-Redox Bypass Hypothesis: Part B-Selenocompounds in the Management of Early Sepsis

Significance: Endothelial barrier damage, which is in part caused by excess production of reactive oxygen, halogen and nitrogen species (ROHNS), especially peroxynitrite (ONOO^-), is a major event in early sepsis and, with leukocyte hyperactivation, part of the generalized dysregulated immune response to infection, which may even become a complex maladaptive state. Selenoenzymes have major antioxidant functions. Their synthesis is related to the need to limit deleterious oxidant redox cycling by small selenocompounds, which may be of therapeutic cytotoxic interest. Plasma selenoprotein-P is crucial for selenium transport from the liver to the tissues and for antioxidant endothelial protection, especially against ONOO^-. Above micromolar concentrations, sodium selenite (Na₂SeO₃) becomes cytotoxic, with a lower cytotoxicity threshold in activated cells, which has led to cancer research. Recent Advances: Plasma selenium (<2% of total body selenium) is mainly contained in selenoprotein-P, and concentrations decrease rapidly in the early phase of sepsis, because of increased selenoprotein-P binding and downregulation of hepatic synthesis and excretion. At low concentrations, Na₂SeO₃ acts as a selenium donor, favoring selenoprotein-P synthesis in physiology, but probably not in the acute phase of sepsis. Critical Issues: The cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes, especially the most immature forms that liberate ROHNS, may be beneficial, but they may also be harmful for activated endothelial cells. Endothelial protection against ROHNS by selenoprotein-P may reduce Na₂SeO₃ toxicity, which is increased in sepsis. Future Direction: The combination of selenoprotein-P for endothelial protection and the cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes may be a promising intervention for early sepsis. Antioxid. Redox Signal. 37, 998-1029.

Selenium, Selenoproteins, and Immunity

Selenium is an essential micronutrient that plays a crucial role in development and a wide variety of physiological processes including effect immune responses. The immune system relies on adequate dietary selenium intake and this nutrient exerts its biological effects mostly through its incorporation into selenoproteins. The selenoproteome contains 25 members in humans that exhibit a wide variety of functions. The development of high-throughput omic approaches and novel bioinformatics tools has led to new insights regarding the effects of selenium and selenoproteins in human immuno-biology. Equally important are the innovative experimental systems that have emerged to interrogate molecular mechanisms underlying those effects. This review presents a summary of the current understanding of the role of selenium and selenoproteins in regulating immune cell functions and how dysregulation of these processes may lead to inflammation or immune-related diseases.

The effect of micronutrient supplementation on active TB incidence early in HIV infection in Botswana

BACKGROUND

Coinfection with active tuberculosis (TB) is one of the leading causes of death in people living with HIV (PLWH) in Africa. This investigation explores the role of micronutrient supplementation in preventing active TB in PLWH.

METHODS

A randomized trial of nutritional supplementation was conducted among antiretroviral- naïve (without previous antiretroviral treatment [ART]) HIV-infected people in Botswana between 2004 and 2009. The study had a factorial design with four arms: the selenium (Se) alone arm, the multivitamins (MVT) alone arm that contained vitamin B complex and vitamins C and E, the combined Se+MVT group and the placebo group. Those participants with prior or current active TB were excluded, as were participants with advanced HIV disease (CD4 <250 cells/μL) or who had already qualified for ART. HIV-positive adults (N=878) were followed monthly for study pill dispensation, every 3 months for CD4 cell count and every 6 months for viral load during 24 months or until they were started on ART.

RESULTS

The participants' characteristics were not significantly different among the four groups at baseline. Supplementation with Se alone (hazard ratio =0.20, 95% confidence interval: 0.04, 0.95, P=0.043) and the two combined SE groups (Se and Se+MVT) had significantly lower risk of developing incident TB disease compared with placebo in multivariate adjusted models (hazard ratio=0.32, 95% confidence interval: 0.11, 0.93, P=0.036). Multivitamins alone did not affect the incidence of TB. Isoniazid preventive therapy was received by 12.2% of participants, a rate that was not significantly different among the four study arms (P=0.122) and the newly diagnosed cases.

CONCLUSION

Se supplementation, alone and with MVT, decreased the incidence of TB disease in PLWH who were ART-naïve. Supplementation with these micronutrients should be considered in HIV infection, prior to ART, in areas where TB and malnutrition are endemic.

Socio-economic determinants of disease progression among HIV infected adults in Kenya

Background

Socioeconomic determinants have been shown to have an effect on the progression of HIV disease evidenced by studies carried out largely in developed countries. Knowledge of these factors could inform on prioritization of populations during scale up of highly active antiretroviral therapy (HAART) constrained health systems. The objective of this study was to identify socioeconomic correlates of HIV disease progression in an adult Kenyan population.

Methods

We analysed data from 312 HIV positive individuals, drawn from a cohort enrolled in a randomized clinical trial investigating the effectiveness of Acyclovir in the prevention of HIV transmission among serodiscordant couples. In this study we included individuals with CD4 counts ≥ 350 cells/mm³ and World Health Organization (WHO), clinical stage one or two. The exposure variables measured were: - daily household income available for expenditure, age, gender, housing type and level of formal education. We used a composite outcome of disease progression to WHO clinical stage 3 or 4 or a laboratory outcome of CD4 count below 350 cells/mm³ after two years of follow-up. Logistic regression was used to determine associations of variables that were found to be significant at univariate analysis, and to control for potential confounders.

Results

Seventy eight (25 %) individuals reported HIV disease progression. Majority (79.9 %) were female. The median age was 30 year and 93.6 % had attained a primary level of education. Median CD4 at enrolment into the clinical trial was 564 cells/mm³; those who had disease progression were enrolled with a significantly (p < 0.001) lower CD4 count. Daily household income available for expenditure adjusted for CD4 count at enrolment was associated significantly (p = 0.04) with HIV disease progression. Disease progression was five times more likely to occur in study subjects with daily income available for expenditure of less than US$1 compared to those with more than US$ 5 available for daily expenditure [adjusted Odds Ratio 4.6 (95 % Confidence Interval 1.4–14.4)]. Disease progression was not associated with age, gender, type of housing or level of education attained (p < 0.05).

Conclusion

Populations with low household incomes should be considered vulnerable to disease progression and should therefore be prioritized during the scale up of HAART for treatment as prevention.

Nutritional supplementation with the mushroom Agaricus sylvaticus reduces oxidative stress in children with HIV

BACKGROUND

The involvement of free radicals and oxidative stress in HIV infection has been extensively studied, and the benefits of antioxidant supplementation in animal studies have been demonstrated. However, few studies have demonstrated a benefit in clinical studies.

OBJECTIVE

To verify the effects of dietary supplementation with Agaricus sylvaticus, a mushroom rich in antioxidants, on the oxidative profile of children born with HIV undergoing antiretroviral therapy.

DESIGN

The sample included 24 children (both boys and girls) between two and eight years of age, of whom 10 were HIV positive and received supplementation with Agaricus sylvaticus for a three-month period, and 14 were HIV negative and received no supplementation. At the beginning and conclusion of the study, thiobarbituric acid-reactive substances (TBARS), nitrite and nitrate (NN), Trolox equivalent antioxidant capacity, and the antioxidant capacity of inhibition of diphenyl-picrilhidrazil (DPPH) free radicals were analyzed.

RESULTS

Before supplementation, significantly higher values of TBARS and NN, but decreased values of DPPH, were observed in infected subjects when compared with HIV-negative subjects. After supplementation, a reduction of TBARS and NN values and an increase in DPPH and Trolox equivalent antioxidant capacity values were observed in HIV-positive subjects.

CONCLUSIONS

The results of the present study suggest the involvement of oxidative stress in HIV infection, with the participation of NN synthesis. Additionally, supplementation reversed oxidative alterations and improved antioxidant defense in infected individuals, and may become a complementary strategy in the treatment of these patients.

Assessing Nutrient Intake and Nutrient Status of HIV Seropositive Patients Attending Clinic at Chulaimbo Sub-District Hospital, Kenya

Background. Nutritional status is an important determinant of HIV outcomes. Objective. To assess the nutrient intake and nutrient status of HIV seropositive patients attending an AIDS outpatient clinic, to improve the nutritional management of HIV-infected patients. Design. Prospective cohort study. Setting. Comprehensive care clinic in Chulaimbo Sub-District Hospital, Kenya. Subjects. 497 HIV sero-positive adults attending the clinic. Main Outcome Measures. Evaluation of nutrient intake using 24-hour recall, food frequency checklist, and nutrient status using biochemical assessment indicators (haemoglobin, creatinine, serum glutamate pyruvate (SGPT) and mean corpuscular volume (MCV)). Results. Among the 497 patients recruited (M : F sex ratio: 1.4, mean age: 39 years ± 10.5 y), Generally there was inadequate nutrient intake reported among the HIV patients, except iron (10.49 ± 3.49 mg). All the biochemical assessment indicators were within normal range except for haemoglobin 11.2 g/dL (11.4 ± 2.60 male and 11.2 ± 4.25 female). Conclusions. Given its high frequency, malnutrition should be prevented, detected, monitored, and treated from the early stages of HIV infection among patients attending AIDS clinics in order to improve survival and quality of life.

Micronutrient concentrations and subclinical atherosclerosis in adults with HIV

BACKGROUND

Extremes in micronutrient intakes are common in HIV-infected patients in developed countries and may affect the progression of atherosclerosis in this population.

OBJECTIVE

We completed a cross-sectional study examining the association between serum micronutrient concentrations and surrogate markers of atherosclerosis in a cohort of HIV-infected adults.

DESIGN

We measured serum selenium, zinc, vitamin A, and vitamin E concentrations as well as carotid intima-media thickness (c-IMT) and coronary artery calcium (CAC) in 298 Nutrition for Healthy Living participants. We assessed cardiovascular disease risk factors, c-IMT, and CAC for each micronutrient tertile by using a chi-square test for binary variables and analysis of variance for continuous variables. We performed multivariate regression of c-IMT and CAC with each micronutrient with adjustment for HIV-related and cardiovascular disease risk factors.

RESULTS

In the multivariate analysis, the highest tertile of serum vitamin E concentration was associated with higher common and internal c-IMT and CAC scores (P < 0.05 for c-IMT and CAC). Participants with higher vitamin E concentrations were more likely to have detectable CAC (50% compared with 44% compared with 67% for tertiles 1, 2, and 3, respectively; P = 0.004) and common c-IMT >0.8 mm (5% compared with 4% compared with 17% for tertiles 1, 2, and 3, respectively; P = 0.002). Other than vitamin E, micronutrients had no association with markers of atherosclerosis.

CONCLUSIONS

Our study showed that elevated serum vitamin E concentrations are associated with abnormal markers of atherosclerosis and may increase the risk of cardiovascular complications in HIV-infected adults.

High-selenium wheat: biofortification for better health

The metalloid Se is ubiquitous in soils, but exists mainly in insoluble forms in high-Fe, low-pH and certain leached soils, and hence is often of limited availability to plants. Consequently, it is often supplied by plants to animals and human consumers at levels too low for optimum health. Se deficiency and suboptimality are manifested in populations as increased rates of thyroid dysfunction, cancer, severe viral diseases, cardiovascular disease and various inflammatory conditions. Se deficiency probably affects at least a billion individuals. Optimal cancer protection appears to require a supra-nutritional Se intake, and involves several mechanisms, which include promotion of apoptosis and inhibition of neo-angiogenesis. Evidence suggests that in some regions Se is declining in the food chain, and new strategies to increase its intake are required. These could include education to increase consumption of higher-Se foods, individual supplementation, food fortification, supplementation of livestock, Se fertilisation of crops and plant breeding for enhanced Se accumulation. Se levels in Australian residents and wheat appear to be above the global estimated mean. Wheat is estimated to supply nearly half the Se utilised by most Australians. Increasing the Se content of wheat represents a food systems approach that would increase population intake, with consequent probable improvement in public health and large health cost savings. The strategies that show most promise to achieve this are biofortification by Se fertilisation and breeding wheat varieties that are more efficient at increasing grain Se density. Research is needed in Australia to determine the most cost-effective fertilisation methods, and to determine the extent of genetic variability for grain Se accumulation. Before recommending large-scale fortification of the food supply with Se, it will be necessary to await the results of current intervention studies with Se on cancer, HIV and AIDS, and asthma.

Factors associated with serum retinol, alpha-tocopherol, carotenoids, and selenium in Hispanics with problems of HIV, chronic hepatitis C, and drug use

The effects of hepatitis and drug use on nutritional problems in HIV infection have rarely been examined despite the importance of drug use in the global HIV pandemic. We examined the effects of HIV, hepatitis C, and drug use on serum micronutrients in 300 US Hispanic adults. Chronic hepatitis C infection was associated with lower serum retinol (-8.2 microg/dl, P < 0.0001), alpha-tocopherol (-0.10 ln microg/dl, P = 0.024), and carotenoids (-19.8 microg/dl, P < 0.0001). HIV infection was associated with lower selenium (-6.1 microg/l, P = 0.028). Elevated triglycerides in HIV infection were associated with higher serum retinol and alpha-tocopherol. Drug use was not independently associated with micronutrient alterations. We conclude that hepatitis C is an important determinant of low serum micronutrients, and should be considered in any nutritional assessment of HIV infected populations. As the safety of micronutrient supplementation is not established, policy for appropriate HIV clinical care should distinguish between populations with and without hepatitis coinfection.

The oxidative stress-induced niacin sink (OSINS) model for HIV pathogenesis

Although several specific micronutrient deficiencies are associated with disease progression and increased mortality risk in HIV/AIDS, and even a simple multivitamin/mineral supplement can prolong survival, this is typically viewed merely as nutritional support of the immune system, and only necessary if there are deficiencies to be rectified. However, the reality is more complex. Several striking nutrient-related metabolic abnormalities have been consistently documented in HIV infection. One is chronic oxidative stress, including a drastic depletion of cysteine from the glutathione pool, and a progressive decline of serum selenium that is correlated with disease progression and mortality. Another is decreased blood levels of tryptophan, with an associated intracellular niacin deficiency. Tryptophan depletion or "deletion" by induction of indoleamine-2,3-dioxygenase (IDO), the first step in oxidative tryptophan metabolism, is a known mechanism for immune suppression that is of critical importance in cancer and pregnancy, and, potentially, in HIV/AIDS. Existing evidence supports the hypothesis that these nutrient-related metabolic abnormalities in HIV infection regarding antioxidants, selenium, sulfur, tryptophan and niacin are interrelated, because HIV-associated oxidative stress can induce niacin/NAD+ depletion via activation of poly(ADP-ribose) polymerase (PARP), which could lead to tryptophan oxidation for compensatory de novo niacin synthesis, thereby contributing to immune tolerance and T-cell loss via tryptophan deletion and PARP-induced cell death. This "oxidative stress-induced niacin sink" (OSINS) model provides a mechanism whereby the oxidative stress associated with HIV infection can contribute to immunosuppression via tryptophan deletion. This model is directly supported by evidence that antioxidants can counteract indoleamine-2,3-dioxygenase (IDO), providing the critical link between oxidative stress and tryptophan metabolism proposed here. The OSINS model can be used to guide the design of nutraceutical regimens that can effectively complement antiretroviral therapy for HIV/AIDS.

How to use the world's scarce selenium resources efficiently to increase the selenium concentration in food

The world's rare selenium resources need to be managed carefully. Selenium is extracted as a by-product of copper mining and there are no deposits that can be mined for selenium alone. Selenium has unique properties as a semi-conductor, making it of special value to industry, but it is also an essential nutrient for humans and animals and may promote plant growth and quality. Selenium deficiency is regarded as a major health problem for 0.5 to 1 billion people worldwide, while an even larger number may consume less selenium than required for optimal protection against cancer, cardiovascular diseases and severe infectious diseases including HIV disease. Efficient recycling of selenium is difficult. Selenium is added in some commercial fertilizers, but only a small proportion is taken up by plants and much of the remainder is lost for future utilization. Large biofortification programmes with selenium added to commercial fertilizers may therefore be a fortification method that is too wasteful to be applied to large areas of our planet. Direct addition of selenium compounds to food (process fortification) can be undertaken by the food industry. If selenomethionine is added directly to food, however, oxidation due to heat processing needs to be avoided. New ways to biofortify food products are needed, and it is generally observed that there is less wastage if selenium is added late in the production chain rather than early. On these bases we have proposed adding selenium-enriched, sprouted cereal grain during food processing as an efficient way to introduce this nutrient into deficient diets. Selenium is a non-renewable resource. There is now an enormous wastage of selenium associated with large-scale mining and industrial processing. We recommend that this must be changed and that much of the selenium that is extracted should be stockpiled for use as a nutrient by future generations.

Thioredoxin reductase-1 negatively regulates HIV-1 transactivating protein Tat-dependent transcription in human macrophages

Epidemiological studies suggest a correlation between severity of acquired immunodeficiency syndrome (AIDS) and selenium deficiency, indicating a protective role for this anti-oxidant during HIV infection. Here we demonstrate that thioredoxin reductase-1 (TR1), a selenium-containing pyridine nucleotide-disulfide oxidoreductase that reduces protein disulfides to free thiols, negatively regulates the activity of the HIV-1 encoded transcriptional activator, Tat, in human macrophages. We used a small interfering RNA approach as well as a high affinity substrate of TR1, ebselen, to demonstrate that Tat-dependent transcription and HIV-1 replication were significantly increased in human macrophages when TR1 activity was reduced. The increase in HIV-1 replication in TR1 small interfering RNA-treated cells was independent of the redox-sensitive transcription factor, NF-kappaB. These studies indicate that TR-1 acts as a negative regulator of Tat-dependent transcription. Furthermore, in vitro biochemical assays with recombinant Tat protein confirmed that TR1 targets two disulfide bonds within the Cys-rich motif required for efficient HIV-1 transactivation. Increasing TR1 expression along with other selenoproteins by supplementing with selenium suggests a potential inexpensive adjuvant therapy for HIV/AIDS patients.

Effects of an oral superoxide dismutase enzyme supplementation on indices of oxidative stress, proviral load, and CD4:CD8 ratios in asymptomatic FIV-infected cats

This study was designed to test the effect of antioxidant supplementation on feline immunodeficiency virus (FIV)-infected felines. Six acutely FIV-infected cats (> or =16 weeks post-inoculation) were given a propriety oral superoxide dismutase (SOD) supplement (Oxstrin; Nutramax Laboratories) for 30 days. Following supplementation, the erythrocyte SOD enzyme concentration was significantly greater in the supplemented FIV-infected group than the uninfected control group or the unsupplemented FIV-infected group. The CD4+ to CD8+ ratio increased significantly (0.66-0.88) in the SOD supplemented FIV-infected cats but not in the unsupplemented FIV-infected cats. Proviral load and reduced glutathione (GSH) levels in leukocyte cell types did not change significantly following supplementation. Antioxidant supplementation resulted in an increase in SOD levels, confirming the oral bioavailability of the compound in FIV-infected cats. This result warrants further investigation with trials of antioxidant therapy in FIV-infected cats that are showing clinical manifestations of their disease, as well as in other feline patients where oxidative stress likely contributes to disease pathogenesis, such as diabetes mellitus and chronic renal failure.

Trends in selenium status of South Australians

OBJECTIVE

To assess trends in selenium status in South Australians from 1977 to 2002.

DESIGN

Six cross-sectional surveys.

PARTICIPANTS

117 participants in 1977, 30 in 1979, 96 and 103 (separate surveys) in 1987, 200 in 1988, and 288 volunteer blood donors in 2002. A total of 834 healthy Australian adults (mean age, 42 years [range, 17-71 years]; 445 were male).

MAIN OUTCOME MEASURES

Plasma and whole blood selenium concentrations.

RESULTS

The 2002 survey yielded a mean plasma selenium concentration of 103 micro g/L (SE, 0.65), which reached the estimated nutritional adequacy level of 100 micro g/L plasma selenium. Mean whole blood selenium declined 20% from the 1977 and 1979 surveys (mean whole blood selenium concentration, 153 micro g/L) to the 1987, 1988 and 2002 surveys (mean whole blood selenium concentration, 122 micro g/L). Plasma selenium was higher in men (P = 0.01), and increased with age in both men and women (P = 0.008).

CONCLUSIONS

In healthy South Australian adults sampled from 1977 to 2002, whole blood and plasma selenium concentrations were above those reported for most other countries and in most previous Australian studies, notwithstanding an apparent decline in selenium status from the late 1970s to the late 1980s.

General nutrition management in patients infected with human immunodeficiency virus

Nutritional management is integral to the care of all patients infected with human immunodeficiency virus (HIV). HIV infection results in complicated nutritional issues for patients, and there is growing evidence that nutritional interventions influence health outcomes in HIV-infected patients. We define levels of nutritional care, and we discuss when patients should be referred to providers (i.e., registered dietitians) with nutritional and HIV expertise.

The antioxidant role of selenium and seleno-compounds

Selenium (Se) is an essential trace element for animals and humans that is obtained from dietary sources including cereals, grains and vegetables. The Se content of plants varies considerably according to its concentration in soil. Plants convert Se mainly into Se-methionine (Se-Met) and incorporate it into protein in place of methionine (Met). Selenocystine (Se-Cys), methyl-Se-Cys and gamma-glutamyl-Se-methyl-Cys are not significantly incorporated into plant protein and are at relatively low levels irrespective of soil Se content. Higher animals are unable to synthesize Se-Met and only Se-Cys was detected in rats supplemented with Se as selenite. Renal regulation is the mode by which whole body Se is controlled. Se is concentrated in hair and nail and it occurs almost exclusively in organic compounds. The potentiating effect of Se deficiency on lipid peroxidation is enhanced in some tissues by concurrent deficiency of copper or manganese. In the in vitro system, the chemical form of Se is an important factor in eliciting cellular responses. Although the cytotoxic mechanisms of selenite and other redoxing Se compounds are still unclear, it has been suggested that they derive from their ability to catalyze the oxidation of thiols and to produce superoxide simultaneously. Selenite-induced cytotoxicity and apoptosis in human carcinoma cells can be inhibited with copper (CuSO(4)) as an antioxidant. High doses of selenite result in induction of 8-hydroxydeoxyguanosine (8-OHdG) in mouse skin cell DNA and in primary human keratinocytes. It may cause DNA fragmentation and decreased DNA synthesis, cell growth inhibition, DNA synthesis, blockade of the cell cycle at the S/G(2)-M phase and cell death by necrosis. In contrast, in cells treated with methylselenocyanate or Se methylselenocysteine, the cell cycle progression was blocked at the G(1) phase and cell death was predominantly induced by apoptosis.

Nutrient intake and body weight in a large HIV cohort that includes women and minorities

OBJECTIVE

Evaluate the baseline nutrient intake of an HIV positive population that includes significant representation from women and minorities, and determine the relationship between state of disease and nutritional intake.

DESIGN

Baseline data from a prospective study (Nutrition for Healthy Living).

SUBJECTS

Individuals with HIV in the Boston and Rhode Island area (n = 516); 25% were women and 30% were minorities.

METHODS

Nutrient intakes from 3-day food records, which included vitamin/mineral supplements, were estimated by gender and nonwhite vs white categories, after grouping by CD4 lymphocyte counts.

STATISTICAL ANALYSES

Spearman correlation coefficients, Wilcoxon signed rank test, Wilcoxon rank sum test, chi2 test, and restricted cubic spline model were used for data analyses as indicated.

RESULTS

Macronutrient but not micronutrient intake was statistically and inversely associated with decreasing CD4 cell counts. The median intake of micronutrients was higher in the study sample compared with the same age and gender group in NHANES III data; however, 25% to 35% of the women in our study sample had dietary intakes of less than 75% of the DRIs for vitamins A, C, E and B-6, and iron and zinc. White men had statistically higher values of all micronutrients compared with nonwhite men. Body mass index for men and women ranged from 23 to 25.

CONCLUSIONS/APPLICATIONS

Median values for micronutrient intake from food plus vitamin/mineral supplements were adequate in the overall population studied, but a large percent of women and minorities had inadequate nutrient intakes and would benefit from dietary assessment and counseling.

Nutrition and HIV infection

Infection by the human immunodeficiency virus (HIV) is characterized by progressive destruction of the immune system, which leads to recurrent opportunistic infections and malignancies, progressive debilitation and death. Malnutrition is one major complication of HIV infection and is recognized as a significant prognostic factor in advanced disease. Malnutrition is multifactorial and poorly treated during the course of HIV. Even if a standardized approach to the management of active weight loss has not been well established, early nutritional intervention is important in HIV infected patients to maximize gain of lean body mass. From early in the era of highly active antiretroviral therapy (HAART), an initial decreased incidence of malnutrition was noted only in western countries while a variety of changes in the distribution of body fat and associated metabolic abnormalities have been recognized under the banner of lipodystrophy.

Anthropometric indices as predictors of survival in AIDS adults. Aquitaine Cohort, France, 1985-1997. Groupe d'Epidémiologie Clinique du Sida en Aquitaine (GECSA)

The aim of the study was to assess the performance of weight related nutritional markers [reported involuntary weight loss (WL) greater than 10%, measured WL and body mass index (BMI)] in predicting survival at AIDS stage. The three anthropometric indices were used as time dependent variables in Cox models to predict survival at AIDS stage. The studied sample included 630 HIV1-infected individuals of a prospective cohort of those 421 died (median survival at AIDS stage: 19.9 months). After adjustment for usual prognostic factors of survival, the reported WL greater than 10% was a pejorative predictor of survival (hazard ratio (HR) 2.4; 95% confidence interval (CI): 1.9-3.0). For measured WL < 5%, between 5 and 10% and > or = 10% of baseline weight compared with no WL, HR were respectively, 1.9 (CI: 1.4-2.6), 3.3 (CI: 2.4-4.4) and 6.7 (CI: 5.2-8.6). The HR of death were 2.2 (CI: 1.6-3.0) for BMI between 16 and 18.4 kg/m2 and 4.4 (CI: 3.1-6.3) for BMI < 16 compared to normal BMI (> or = 18.5). Even a limited WL measured at a given point in time during follow up increases the risk of death at the AIDS stage. Simple cross-sectional measures of BMI have a good predictive value of survival.

Evolution of selenocysteine-containing proteins: significance of identification and functional characterization of selenoproteins

In the genetic code, UGA serves as either a signal for termination or a codon for selenocysteine (Sec). Sec rarely occurs in protein and is different from other amino acids in that much of the biosynthetic machinery governing its incorporation into protein is unique to this amino acid. Sec-containing proteins have diverse functions and lack a common amino acid motif or consensus sequence. Sec has previously been considered to be a relic of the primordial genetic code that was counter-selected by the presence of oxygen in the atmosphere. In the present report, it is proposed that Sec was added to the already existing genetic code and its use has accumulated during evolution of eukaryotes culminating in vertebrates. The more recently evolved selenoproteins appear to take advantage of unique redox properties of Sec that are superior to those of Cys for specific biological functions. Further understanding of the evolution of selenoproteins as well as biological properties and biomedical applications of the trace element selenium requires identification and functional characterization of all mammalian selenoproteins.

Diarrhea and abnormalities of gastrointestinal function in a cohort of men and women with HIV infection

OBJECTIVE

The aim of this study was to determine the prevalence of gastrointestinal dysfunction in the era of improved treatment of HIV infection.

METHODS

Gastrointestinal function was studied cross-sectionally in 671 persons with HIV. Absorptive function was measured by a 25-g D-xylose test, a Sudan-III stain for fecal fat on a 100-g fat diet, and serum levels of micronutrients.

RESULTS

Eighty-eight percent had at least one abnormality of gastrointestinal function: 47.7% had low D-xylose absorption; 40.3% had a history of liver disease; 38.9% had diarrhea; 28.3% had chronic diarrhea; 22.5% had borderline or low serum vitamin B12 levels; 12.2% had stool pathogens; and 7.2% were hypoalbuminemic. Men were more likely to have low D-xylose absorption, diarrhea, and stool pathogens than women. Intravenous drug users (IVDUs) were more likely to have a history of liver disease and hypoalbuminemia. However, borderline or low vitamin B12 levels were less frequent in IVDUs; they tended to have less diarrhea and a lower prevalence of stool pathogens. Despite less history of liver disease, 14.1% of women were hypoalbuminemic. Differences in patterns of gastrointestinal dysfunction are unlikely to be due to severity of immunosuppression as abnormalities were seen in all risk groups with CD4 >200 cells/mm3. D-xylose absorption below 30 mg/dl, current diarrhea, and borderline levels of vitamin B12 were associated with advanced immunosuppression.

CONCLUSIONS

Abnormalities of gastrointestinal function are common in the current era of HIV treatment, appear early in the course of HIV infection, and in the absence of diarrhea. Gender and IVDU are important determinants of the type and frequency of gastrointestinal abnormalities.

Complementary and alternative therapies to manage HIV-related symptoms

Persons with HIV infection report substantial use of complementary and alternative medical (CAM) therapies for symptom management. Anecdotal reports from patients indicate that CAM approaches are helpful; however, there is limited scientific information on the safety and efficacy of these therapies in the HIV population. The purpose of this review is to critically appraise the scientific evidence for selected CAM therapies that are used by HIV-infected persons to manage three common symptoms: nutritional alterations, pain, and depression.

Micronutrients and infectious diseases: thoughts on integration of mechanistic approaches into micronutrient research

Results of field and laboratory studies provide convincing evidence that micronutrient deficiencies contribute to the mortality and morbidity of infectious diseases. Despite encouraging results in large trials, understanding the mechanisms by which micronutrients contribute to the outcome of the encounter between an individual and an infectious agent requires additional hypothesis-driven research. Presumably, such understanding should lead to translational studies with targeted nutritional therapy. Although these mechanistic studies are varied and complex, they must be done systematically and should include examination of the mechanisms by which micronutrients affect host-pathogen interactions, development of appropriate animal models and reliable methods for the assessment of micronutrient levels, and translation of the results of basic research findings into clinical studies. Moving the frontiers of micronutrient research from the laboratory to the field will be challenging. However, sound scientific research should lead toward better human health.

Glutamine and arginine: immunonutrients for improved health

There is considerable literature demonstrating that specific nutrients can influence immune function in health and disease. This review will examine the literature and the rational for classifying two amino acids, glutamine (gln) and arginine (arg), as "immunonutrients" during infections. An understanding of immune defenses during infections (virus, parasite, bacteria, protozoa) and metabolism of gln and arg by immune cells is necessary to understand how these nutrients can influence specific functions of the immune system. This review focuses on several key clinical studies in immunosuppressed individuals (burn patients, individuals with cancer and HIV infection, and those undergoing surgery or who have experienced major traumas) that have tested the hypothesis that the provision of gln and/or arg is beneficial to immune function and clinical outcome. These clinical studies support the dietary "essentiality" of these two nutrients for improving immune responses in most immunosuppressive states associated with high rates of infection. However, the role of these nutrients in modulating the immune changes that occur with exercise in healthy athletes demands additional experiments.

Nutritional Contributions to the CNS Pathophysiology of HIV-1 Infection and Implications for Treatment

Nutritional deficiencies are commonplace in patients with human immunodeficiency virus type 1 (HIV-1) infection, and recent research has indicated that nutritional factors may play an important role in the pathogenesis of HIV-1 disease. Although nutritional deficiencies are unlikely to be the primary causative factor in disease progression, they may contribute to cognitive dysfunction, neurologic abnormalities, mood disturbance, and immune dysregulation associated with HIV-1 infection. Furthermore, deficiencies of specific micronutrients have been associated with increased risk of HIV-1-associated mortality. This article will briefly summarize the role of macronutrient deficiency, the interactions of specific micronutrient deficiencies with neuropsychiatric functioning, and the role of these factors in HIV-1 disease progression. Since recent research has shown that normalization of many nutritional deficits and supplementation beyond normal levels are associated with improvements in neuropsychiatric functioning, potential treatment implications will also be discussed.

New mammalian selenocysteine-containing proteins identified with an algorithm that searches for selenocysteine insertion sequence elements

Mammalian selenium-containing proteins identified thus far contain selenium in the form of a selenocysteine residue encoded by UGA. These proteins lack common amino acid sequence motifs, but 3'-untranslated regions of selenoprotein genes contain a common stem-loop structure, selenocysteine insertion sequence (SECIS) element, that is necessary for decoding UGA as selenocysteine rather than a stop signal. We describe here a computer program, SECISearch, that identifies mammalian selenoprotein genes by recognizing SECIS elements on the basis of their primary and secondary structures and free energy requirements. When SECISearch was applied to search human dbEST, two new mammalian selenoproteins, designated SelT and SelR, were identified. We determined their cDNA sequences and expressed them in a monkey cell line as fusion proteins with a green fluorescent protein. Incorporation of selenium into new proteins was confirmed by metabolic labeling with (75)Se, and expression of SelT was additionally documented in immunoblot assays. SelT and SelR did not have homology to previously characterized proteins, but their putative homologs were detected in various organisms. SelR homologs were present in every organism characterized by complete genome sequencing. The data suggest applicability of SECISearch for identification of new selenoprotein genes in nucleotide data bases.