High risk of HIV-related mortality is associated with selenium deficiency

Impact of a selenium chemoprevention clinical trial on hospital admissions of HIV-infected participants

PURPOSE

To evaluate the impact of selenium chemoprevention (200 microg/day) on hospitalizations in HIV-positive individuals.

METHOD

Data were obtained from 186 HIV+ men and women participating in a randomized, double-blind, placebo-controlled selenium clinical trial (1998-2000). Supplements were dispensed monthly, and clinical evaluations were conducted every 6 months. Inpatient hospitalizations, hospitalization costs, and rates of hospitalization were determined 2 years before and during the trial.

RESULTS

At enrollment, no significant differences in CD4 cell counts or viral burden were observed between the two study arms. Fewer placebo-treated participants were using antiretrovirals (p <.05). The total number of hospitalizations declined from 157 before the trial to 103 during the 2 year study. A marked decrease in total admission rates (RR = 0.38; p =.002) and percent of hospitalizations due to infection/100 patients for those receiving selenium was observed (p =.01). As a result, the cost for hospitalization decreased 58% in the selenium group, compared to a 30% decrease in the placebo group (p =.001). In the final analyses, selenium therapy continued to be a significant independent factor associated with lower risk of hospitalization (p =.001).

CONCLUSION

Selenium supplementation appears to be a beneficial adjuvant treatment to decrease hospitalizations as well as the cost of caring for HIV-1-infected patients.

Selenium-based pharmacological agents: an update

The biochemistry and pharmacology of selenium is a subject of intense current interest, particularly from the viewpoint of public health. Selenium, long recognised as a dietary antioxidant, is now known to be an essential component of the active sites of several enzymes, including glutathione peroxidase and thioredoxin reductase, which catalyse reactions essential to the protection of cellular components against oxidative and free radical damage. A low concentration of selenium in plasma has been identified as a risk factor for several diseases, including cancer, cardiovascular disease, osteoarthritis and AIDS, and several large-scale selenium supplementation human trials are now underway. Evidence is emerging that, at least in the case of cancer, the antitumorigenic effect of selenium supplementation arises at least in part from enhanced production of specific selenium-containing metabolites, not just from maximal expression of selenoenzymes. Therefore a number of novel pharmaceutical agents which are selenium-based or which target specific aspects of selenium metabolism are under development. Among these are orally-active antihypertensive agents, anticancer, antiviral, immunosuppressive and antimicrobial agents, and organoselenium compounds which reduce oxidative tissue damage and edema. It can be anticipated that as our understanding of the basic biology and biochemistry of selenium increases, the coming years will bring further development of new selenium-based pharmaceutical agents with therapeutic potential toward a variety of human diseases.

HIV type 1 glycoprotein 120 inhibits cardiac myocyte contraction

Cardiomyopathy is a common, life-threatening, but poorly understood complication of HIV infection. The purpose of the present study is to study the effects of an HIV surface envelope protein, glycoprotein 120 (gp120), on cell contraction and L-type Ca(2+) current in rabbit ventricular myocytes. Rabbit ventricular cells were isolated by an enzyme dissociation method. Cell contractions were induced by electric field stimulation. Whole cell L-type Ca(2+) channel currents were measured by the whole cell voltage-clamp technique. We found that perfusion with solution containing gp120 (0.1 microg/ml) derived from HIV-1(SF2) significantly inhibited field-stimulated contractions and L-type Ca(2+) current in rabbit ventricular myocytes as compared with perfusion with buffer alone. These results suggest that HIV-1 gp120 may directly contribute to cardiac dysfunction as seen in many HIV patients.

Micronutrients and vertical transmission of HIV-1

ABSTRACT Vertical transmission of HIV from mother to infant can occur during pregnancy, at the time of delivery, or post-natally through breast-feeding and is a major factor in the continuing spread of HIV infection. Inadequate nutritional status may increase the risk of vertical HIV transmission by influencing mater-nal and child factors for transmission. The potential effects on these factors include impaired systemic immune function in pregnant women, fetuses, and children; an increased rate of clinical, immunologic, and virologic disease progression; impaired epithelial integrity of the placenta and genital tract; increased viral shedding in breast milk from inflammation of breast tissue; increased risk of low birth weight and preterm birth; and impaired gastrointestinal immune function and integrity in fetuses and children. Micronutrient deficiencies are prevalent in many HIV-infected populations, and numerous studies have reported that these deficiencies impair immune responses, weaken epithelial integrity, and are associated with accelerated HIV disease progression. Although low serum vitamin A concentrations were shown to be associated with an increased risk of vertical HIV transmission in prospective cohort studies, randomized, placebo-controlled trials have reported that vitamin A and other vitamin supplements do not appear to have an effect on HIV transmission during pregnancy or the intrapartum period. However, the ability of prenatal and postpartum micronutrient supplements to reduce transmission during the breast-feeding period is still unknown.

An evaluation of antiretroviral therapy associated with alpha-tocopherol supplementation in HIV-infected patients

In HIV-infected patients, an increase in the production of oxygen-reactive species (ROS) is observed, with a consequent reduction of plasma levels of antioxidants such as alpha-tocopherol. The nuclear transcription factor-kappaB (NF-kappaB) is activated by a prooxidant state in the infected T cells through the release of its inhibitory subunit I-kappaB. The aim of the present work was to evaluate the behavior of hematological parameters and markers of anemia in HIV-infected patients who underwent antiretroviral therapy associated with 800 mg/day alpha-tocopherol supplementation. Blood samples were collected from supplemented (n=9) and not-supplemented (n=9) HIV-seropositive patients (n=18). We observed a decreased viral load in the alpha-tocopherol-supplemented group (p<0.05); other changes, such as an increase in the CD4/CD8 ratio, in the hematocrit and in the hemoglobin concentration were also observed, though lacking statistical significance. We conclude that antiretroviral therapy in association with alpha-tocopherol (800 mg/day) supplementation is more effective in reducing viral load levels and also, possibly, in recovering other hematological parameters after a 60-day period of use.

The argument for increasing selenium intake

The essential trace mineral, Se, is of fundamental importance to human health. As a constituent of selenoproteins it plays both structural and enzymic roles, in the latter context being best known as an antioxidant and catalyst for the production of active thyroid hormone. While Se-deficiency diseases have been recognised for some time, evidence is mounting that less-overt deficiency can also cause adverse health effects and furthermore, that supra-nutritional levels of Se may give additional protection from disease. In the context of these effects, low or diminishing Se status in some parts of the world, notably in some European countries such as the UK, is giving cause for concern. While deficiency has an adverse effect on immunocompetence, Se supplementation appears to enhance the immune response. Se appears to be a key nutrient in counteracting certain viral infections; thus, in a Se-deficient host the benign coxsackie virus becomes virulent, causing heart damage, the influenza virus causes more serious lung pathology and HIV infection progresses more rapidly to AIDS. Long recognised as essential for successful animal reproduction, Se is required for human sperm maturation and sperm motility and may reduce the risk of miscarriage. Deficiency has been linked to adverse mood states. Findings have been equivocal in linking Se to cardiovascular disease risk, although other conditions involving oxidative stress and inflammation have shown some association with Se status. There is growing evidence that higher Se intakes are associated with reduced cancer risk. While persuasive evidence already exists to suggest that additional Se would be beneficial in some health conditions, results from intervention trials underway or planned have the potential to reinforce or refute the argument for increasing Se intake.

Selenium and the regulation of cell signaling, growth, and survival: molecular and mechanistic aspects

In the past 30 years, it has been recognized that dietary selenium (Se) is essential for the normal function of many of the systems of the body. Furthermore, low Se intake can have deleterious effects on several aspects of human and animal health. The importance of Se is characterized in its role as a constituent of several key antioxidant and redox enzyme families. Most of the effects of Se are probably mediated by selenoproteins, which have the micronutrient covalently incorporated into the protein. The purpose of this review is to examine basic mechanisms by which Se regulates cell growth, gene transcription, cell signaling, and cell death. We start with the historical background to Se. The synthesis and function of selenoproteins are described, followed by details of the dietary sources of Se and Se status in different parts of the world, together with the clinical effects of Se deficiency and toxicity. We consider some aspects of the molecular mechanisms by which Se modulates cell growth, intracellular signaling, and gene transcription.

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.

Impact of selenium status on the pathogenesis of mycobacterial disease in HIV-1-infected drug users during the era of highly active antiretroviral therapy

The risk of mycobacterial disease is significantly increased in drug abusers as well as in immunocompromised HIV-1-infected individuals. The essential trace element selenium has an important function in maintaining immune processes and may, thus, have a critical role in clearance of mycobacteria. The impact of selenium status on the development of mycobacterial diseases in HIV-1-seropositive drug users was investigated over a 2-year period (1999-2001). Twelve cases of mycobacterial disease (tuberculosis, 9; infection due to atypical Mycobacterium species, 3) occurred; these 12 cases were compared with 32 controls with no history of respiratory infections who were matched on age, sex, and HIV status. Significant risk for development of mycobacterial disease was associated with a CD4 cell count of <200/mm 3, malnutrition, and selenium levels of <or=135 microg/L (patients with these levels were 13 times more likely to develop mycobacterial disease). Multivariate analyses controlling for antiretroviral treatment and CD4 cell count revealed that both body mass index and selenium level remained significant factors in the relative risk for developing mycobacterial disease (relative risk, 3; p =.015); these findings suggest that selenium status may have a profound impact on the pathogenesis of mycobacterial disease.

Selenite suppresses hydrogen peroxide-induced cell apoptosis through inhibition of ASK1/JNK and activation of PI3-K/Akt pathways

The relationship between selenium and signal molecules has not been well elucidated. It was found that physiological concentration of selenite, 3 microM, reduced ASK1 activity and induced PI3-kinase (PI3-K)/Akt pathways in HT1080 cells. Duration of these signal molecules by selenite was much longer than that by growth factors and other stresses. The longer duration time of these signal molecules may be important to maintain normal functions against stresses. Selenite increased cell proliferation through up-regulation of Bcl-2 expression, mitochondrial membrane potential, adenosine triphosphate (ATP) generation, and glucose uptake mediated by PI3-K pathway. High concentration of H2O2 increased an apoptotic signal molecule, ASK1, which resulted in Bcl-2 down-regulation, membrane potential disruption, decreased ATP and glucose uptake, and activation of caspases. However, an antiapoptotic signal molecule, Akt, was activated also by H2O2, but duration of its activation was much shorter. Selenite blocked apoptosis induced by H2O2, which was related to blocking ASK1 and further stimulating PI3-kinase/Akt activities. Selenite blocked mitochondrial membrane potential disruption by 400 mM H2O2. Selenite also blocked caspase-9 and -3 activities and apoptosis induced by 500 microM H2O2, even after mitochondrial membrane potential disruption. These observations demonstrate that selenite increases cell proliferation and maintains cell survival by activating the antiapoptotic signal and blocking the apoptotic signal.

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.

Micronutrients and child health: studies in international nutrition and HIV infection

Increasing data link micronutrient deficiencies to excess childhood morbidity and mortality, and similar relationships have been noted in the study of nutrition and HIV infection. We review epidemiologic studies that have examined the relationship between micronutrient deficiencies and health outcomes in childhood and HIV infection, as well as clinical trials of micronutrient supplementation. Vitamin A supplementation among communities at risk of deficiency effectively reduces mortality and morbidity in children younger than age 5, and vitamin A may be especially effective in HIV-infected children. Vertical transmission of HIV has not to date been affected by maternal micronutrient supplementation. In children with poor dietary zinc intake and/or bioavailability, zinc supplementation reduces the incidence and severity of diarrheal diseases, as well as the occurrence of pneumonia. Vitamin A therapy has not been associated with improved growth, whereas some trials have shown that zinc supplementation is associated with greater increments in height. Further trials of micronutrient supplementation are warranted.

Evaluation of cardiovascular parameters of a selenium-based antihypertensive using pulsed Doppler ultrasound

The pharmacology of selenium is of much interest because selenium deficiency has been linked to cardiovascular diseases, cancer, and arthritis, and selenoenzymes are critical cellular antioxidants. We have previously reported that phenyl-2-aminoethylselenide (PAESe) and its derivatives represent a novel class of selenium-based antihypertensive agents that exhibit unique biochemical and pharmacologic properties. We now report on experiments designed to probe the hemodynamic mechanism of action of these compounds in spontaneously hypertensive rats (SHR). A noninvasive pulsed Doppler ultrasound probe was used to measure peak blood flow velocity in the aortic arch from the right second intercostal space. PAESe was found to increase peak aortic blood flow velocity (+44%), heart rate (+16%), and blood flow acceleration (+105%), while decreasing left ventricular ejection time (LVET) (-37%) concomitant with a decrease in mean arterial pressure (-54%). These results were compared with the known vasodilator hydralazine, which had similar effects on mean arterial pressure (MAP) and peak velocity but caused an increase in LVET (+42%) and a decrease in heart rate (-18%). Taken together, our results suggest that PAESe decreases blood pressure via a decrease in peripheral resistance, which overcomes the initial increase in heart rate and acceleration to give a net decrease in MAP.

Plasma zinc, copper, copper:zinc ratio, and survival in a cohort of HIV-1-infected homosexual men

A prospective cohort study of 121 HIV-1-positive homosexual men was conducted in Miami, Florida, U.S.A. to evaluate the associations between plasma zinc and copper levels and mortality. Plasma zinc and copper levels were measured at baseline and then at semiannual visits. Zinc inadequacy and copper inadequacy were defined as plasma zinc levels <75 (microg/dl) and plasma copper levels <85 (microg/dl), respectively. HIV-1-related deaths were confirmed by review of death certificates. Cox proportional hazards regression models with time-dependent covariates were used to estimate the relative risks of zinc and copper inadequacy on mortality. Over the average course of the 3.3-year follow-up, 19 participants (16%) died of HIV-1-related causes. After adjustment for potential confounders, including low CD4+ cell counts and antiretroviral therapy, zinc inadequacy and copper:zinc ratio >1 (i.e., plasma copper level greater than plasma zinc level) were associated with increased mortality (relative risks [RRs]; 95% confidence intervals [CIs], 4.98, 1.30-19.00 and 8.28, 1.03-66.58, respectively). A negative association was also observed between plasma zinc levels and mortality (RR 0.94; 95% CI, 0.91-0.98). Plasma levels of copper were not significantly associated with mortality. These results suggest that plasma zinc inadequacy or the plasma copper:zinc ratio may be useful predictors of survival in HIV-1 infection. The latter appears to be a stronger predictor.

Selenium deficiency is associated with shedding of HIV-1--infected cells in the female genital tract

OBJECTIVE

To assess the relation between selenium deficiency and vaginal or cervical shedding of HIV-1-infected cells.

DESIGN

Cross-sectional study of 318 HIV-1 seropositive women in Mombasa, Kenya.

METHODS

Vaginal and cervical swab specimens were tested for the presence of HIV-1 DNA by polymerase chain reaction. Multivariate logistic regression models, adjusting for CD4 count and vitamin A deficiency, were used.

RESULTS

Selenium deficiency (defined as levels <85 microg/L) was observed in 11% of the study population. In unstratified multivariate analyses, there was no significant association between selenium deficiency and vaginal or cervical shedding. In stratified analyses, however, significant associations became apparent after excluding women with predictors of shedding with strong local effects on the genital tract mucosa. Among women who did not use oral contraceptives and who did not have vaginal candidiasis, selenium deficiency was significantly associated with vaginal shedding (adjusted odds ratio [AOR] 2.9, 95% confidence interval [CI] 1.0--8.8, p =.05). Effect modification was also observed in the relation between selenium deficiency and cervical shedding, with a significant association seen among those women who were not using oral contraceptive pills or depot medroxyprogesterone acetate and who did not have Neisseria gonorrhoeae infection (AOR 2.8, 95% CI 1.1--7.0, p =.02).

CONCLUSIONS

We found selenium deficiency to be associated with a nearly threefold higher likelihood of genital mucosal shedding of HIV-1--infected cells, suggesting that deficiency may increase the infectiousness of women with HIV-1. Nutritional interventions to prevent HIV-1 transmission warrant investigation.

Nutritional factors and vertical transmission of HIV-1. Epidemiology and potential mechanisms

Transmission of HIV from mothers to children may occur through the transplacental, intrapartum, or breastfeeding routes. Adequate nutritional status may reduce vertical transmission by affecting several maternal or fetal and child risk factors for transmission including enhancing systemic immune function in the mother or fetus/child; reducing the rate of clinical, immunological, or virological progression in the mother; reducing viral load or the risk of viral shedding in lower genital secretions or breast milk; reducing the risks of low birth weight or prematurity; or by maintaining the integrity of the fetus/child gastrointestinal integrity. In prospective observational studies, low plasma vitamin A levels were associated with higher risks of vertical transmission. However, findings from randomized, controlled trials suggest that supplements of vitamin A or other vitamins are unlikely to have an effect on vertical transmission during pregnancy or the intrapartum period. The effect of other nutrient supplements, such as zinc and selenium, is unknown. Similarly, whether nutrition supplements of mothers during the breastfeeding period has an effect on transmission is unknown. The potential benefits of direct supplementation of children born to HIV-infected women on transmission of HIV, as well as on the risk and severity of childhood infections and mortality, are also important to examine.

Nutrition, HIV, and drug abuse: the molecular basis of a unique role for selenium

HIV-infected injection drug users (IDUs) often suffer from serious nutritional deficiencies. This is a concern because plasma levels of micronutrients such as vitamin B12, zinc, and selenium have been correlated with mortality risk in HIV-positive populations. Injection drug use also increases lipid peroxidation and other indicators of oxidative stress, which, combined with antioxidant deficiencies, can stimulate HIV-1 replication through activation of NF-kappaB transcription factors, while weakening immune defenses. As detailed herein, these prooxidant stimuli can also increase the pathogenic effects of HIV-1 by another mechanism, involving viral selenoproteins. Overlapping the envelope coding region, HIV-1 encodes a truncated glutathione peroxidase (GPx) gene (see #6 in reference list). Sequence analysis and molecular modeling show that this viral GPx (vGPx) module has highly significant structural similarity to known mammalian GPx, with conservation of the catalytic triad of selenocysteine (Sec), glutamine, and tryptophan. In addition to other functions, HIV-1 vGPx may serve as a negative regulator of proviral transcription, by acting as an NF-kappaB inhibitor (a known property of cellular GPx). Another potential selenoprotein coding function of HIV-1 is associated with the 3' end of the nef gene, which terminates in a conserved UGA (potential Sec) codon in the context of a sequence (Cys-Sec) identical to the C-terminal redox center of thioredoxin reductase, another cellular regulator of NF-kappaB. Thus, in combination with known cellular mechanisms involving Se, viral selenoproteins may represent a unique mechanism by which HIV-1 monitors and exploits an essential micronutrient to optimize its replication relative to the host.

Role of micronutrients in HIV-infected intravenous drug users

Nutritional deficiencies are widespread among HIV-1-seropositive male and female drug abusers (injecting drug users, or IDUs), among men who have sex with men (MSM), and among children, although the prevalence of nutritional alterations varies among the groups. Low levels of vitamin A, vitamin B12, zinc, and selenium are common and have been demonstrated to be associated with disease progression and HIV-1 related mortality, independent of CD4 count <200 cells/mm3 at baseline and CD4 count over time. When all nutrient factors that are associated with survival are considered together, only selenium deficiency is a significant predictor of mortality. The profound effect of selenium on disease progression may reflect selenium's action in antioxidant defense systems, as well as gene regulation.

Status of selected nutrients and progression of human immunodeficiency virus type 1 infection

BACKGROUND

Immune function is highly dependent on nutritional status because the large mass and high rate of cellular turnover of the immune system make it a major user of nutrients. Furthermore, nutrient requirements may be increased during acute and chronic infections, including HIV-1 infection.

OBJECTIVE

The current study was designed to assess relations among HIV-1 progression and 11 nutritional and demographic variables.

DESIGN

The participants were 106 HIV-infected outpatients and 29 uninfected control subjects (n = 89 men and 46 women; age range: 35-57 y). The HIV-infected subjects represented a broad range of disease progression.

RESULTS

We found lower concentrations of plasma and erythrocyte magnesium and of erythrocyte reduced glutathione beginning early in the course of HIV-1 infection. Significantly decreased hematocrit and increased serum copper concentration developed only late in the course of the disease. Statistically significant univariate associations were found between the CD4(+) T lymphocyte count and hematocrit, plasma magnesium concentration, and plasma zinc concentration. The lowest erythrocyte magnesium concentrations occurred in HIV-infected subjects who consumed alcoholic beverages. Independent variables that were significant joint predictors of CD4(+) cell count in multiple regression analyses were hematocrit and plasma free choline and zinc concentrations. These 3 factors together explained 43% of the variability in CD4(+) cell counts.

CONCLUSION

The results provide evidence that compromised nutritional and antioxidant status begin early in the course of HIV-1 infection and may contribute to disease progression.

The importance of selenium to human health

The essential trace mineral, selenium, is of fundamental importance to human health. As a constituent of selenoproteins, selenium has structural and enzymic roles, in the latter context being best-known as an antioxidant and catalyst for the production of active thyroid hormone. Selenium is needed for the proper functioning of the immune system, and appears to be a key nutrient in counteracting the development of virulence and inhibiting HIV progression to AIDS. It is required for sperm motility and may reduce the risk of miscarriage. Deficiency has been linked to adverse mood states. Findings have been equivocal in linking selenium to cardiovascular disease risk although other conditions involving oxidative stress and inflammation have shown benefits of a higher selenium status. An elevated selenium intake may be associated with reduced cancer risk. Large clinical trials are now planned to confirm or refute this hypothesis. In the context of these health effects, low or diminishing selenium status in some parts of the world, notably in some European countries, is giving cause for concern.

Molecular modeling and in vitro activity of an HIV-1-encoded glutathione peroxidase

Based on theoretical evidence, it has been proposed that HIV-1 may encode several selenoprotein modules, one of which (overlapping the env gp41-coding region) has highly significant sequence similarity to the mammalian selenoprotein glutathione peroxidase (GPx; EC ). The similarity score of the putative HIV-1 viral GPx homolog relative to an aligned set of known GPx is 6.3 SD higher than expected for random sequences of similar composition. Based on that alignment, a molecular model of the HIV-1 GPx was constructed by homology modeling from the bovine GPx crystal structure. Despite extensive truncation relative to the cellular GPx gene, the structural core and the geometry of the catalytic triad of selenocysteine, glutamine, and tryptophan are well conserved in the viral GPx. All of the insertions and deletions predicted by the alignment proved to be structurally feasible. The model is energetically favorable, with a computed molecular mechanics strain energy close to that of the bovine GPx structure, when normalized on a per-residue basis. However, considering the remote homology, this model is intended only to provide a working hypothesis allowing for a similar active site and structural core. To validate the theoretical predictions, we cloned the hypothetical HIV-1 gene and found it to encode functional GPx activity when expressed as a selenoprotein in mammalian cells. In transfected canine kidney cells, the increase in GPx activity ranged from 21% to 43% relative to controls (average 30%, n = 9, P < 0.0001), whereas, in transfected MCF7 cells, which have low endogenous GPx activity, a near 100% increase was observed (average 99%, n = 3, P < 0.05).

HIV heterosexual transmission: a hypothesis about an additional potential determinant

Transmission rates of human immunodeficiency virus (HIV) during heterosexual intercourse vary dramatically around the world. In Asia and South America, they are extraordinarily high, whereas in the United States and Europe, rates are much lower even after a large number of unprotected contacts. The transmission rates in Africa also probably are high, but the available studies unfortunately are weak. In Thailand, female-to-male transmission rates per contact were estimated at.056 (l in 18) compared to.0002 to.0015 (1/5000-1. 5/1000) for male-to-female transmission in the United States and Europe. Male-to-female transmission in Thailand appears to show, as expected, even greater transmission likelihood compared to female-to-male rates. In general, in the United States and Europe, transmission rates within heterosexual couples range from less than 10% to 22%, whereas in Thailand and Brazil, the rates exceed 40%. The much lower transmission rate per contact in the United States and Europe is based on an assumption that HIV transmitters are a homogeneous group. Wiley and colleagues argue that transmitters are likely to be a heterogeneous group with a large percentage of very low frequency transmitters and a small percentage of high frequency transmitters. That hypothesis is given some support by a cluster of cases in rural New York State in which one man appeared to infect 31% of his many contacts.

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.

Comparison of clinical features, CD4 and CD8 responses among patients with acute HIV-1 infection from Geneva, Seattle and Sydney

OBJECTIVE

To compare the clinical features and T-cell subsets among 160 patients with acute HIV-1 infection not treated with antiretroviral agents from three different locations (Geneva, Seattle and Sydney).

DESIGN

Patients with documented acute HIV-1 infection were enrolled in four prospective studies: one randomized placebo controlled trial (RCT) and three observational cohort studies.

SETTING

All patients were diagnosed and followed in three university affiliated tertiary clinical care centers.

METHODS

The chi-square test was used for comparing proportions and one way analysis of variance (ANOVA) for comparing continuous variables among these groups. Multiple regression analysis was used to identify the variables independently associated with the duration of acute HIV-1 infection. The differences in mean CD4 and CD8 load between centers were assessed using the random-effect models for the longitudinal data.

RESULTS

Minor differences were noted in the frequency of symptoms among subjects enrolled at different locations. RCT patients reported a longer duration of symptoms (31 days) compared with that for observational patients (15 days; P < 0.0001). For the most common symptoms such as fever, skin rash, arthralgia, myalgia, and headaches, a longer duration was observed in the RCT group compared with that for observational patients (P range, 0.001 to < 0.0001). T-cells subsets within 100 days of seroconversion did not statistically differ by centre or by mode of recruitment.

CONCLUSIONS

These results suggest a selection bias toward patients with longer symptomatic acute HIV-1 infection enrolled in the RCT. Data collected from RCT are not comparable to that collected in observational studies. However, data from collaborative international studies can be combined.

When obesity is desirable: a longitudinal study of the Miami HIV-1-infected drug abusers (MIDAS) cohort

Despite widespread nutrient deficiencies, a substantial proportion of the MIDAS cohort exhibits obesity, which has been linked to immune dysregulation in other clinical settings. Herein, the effects of obesity on immune function, disease progression, and mortality were evaluated longitudinally in 125 HIV-1-seropositive drug users, with comparison measures in 148 HIV-1-seronegative controls. Data were collected at a community clinic from 1992 to 1996, before administration of highly active antiretroviral therapy. Results indicated that overweight/obesity, defined as body mass index (BMI; kg/m2) > or =27, was evident in 18% of the HIV-1-seropositive patients and 29% of the seronegative patients. At baseline, no significant immunologic differences were observed among lean, nonobese, and obese groups. Over an 18-month period, 60.5% of the nonobese HIV-1-seropositive patients exhibited a 25% decline in CD4 cell count, compared with 18% of the obese patients (p<.004). During the follow-up period, 38% of the lean and 13% of the nonobese study subjects died of HIV-1-related causes. Measurements of BMI were inversely associated with progression to death, independent of CD4 count <200 cells/mm3 (p<.02). These data suggest that mild-to-moderate obesity in HIV-1-infected chronic drug users does not impair immune function and is associated with better HIV-1-related survival.

Prevention of mother-to-child transmission of HIV-1

Several recently published randomized trials have demonstrated that a substantial proportion of the mother-to-child transmission of HIV-1 can be prevented by antiretroviral therapy late in gestation and at delivery to mother and infant. The cost implications of these findings are considerable for resource-poor settings. Preliminary data also suggest very low rates of transmission among mothers receiving maximally suppressive combination drug regimens. Prophylactic cesarean delivery has also been shown to reduce transmission in women not receiving antiretroviral agents, and may play a role in selected patients. The avoidance of breast feeding with infant formula supplementation is clearly protective against HIV-1 transmission, but may not improve infant survival in some poorer settings because of associated increases in other infectious diseases and malnutrition.

Responsiveness of selenoproteins to dietary selenium

Selenocysteine-containing enzymes that have been identified in mammals include the glutathione peroxidase family (GPX1, GPX2, GPX3, and GPX4), one or more iodothyronine deiodinases and two thioredixin reductases. Selenoprotein P, a glycoprotein that contains 10 selenocysteine residues per 43 kDa polypeptide and selenoprotein W, a 10 kDa muscle protein, are unidentified as to function. Levels of all of these selenocysteine-containing proteins in various tissues are affected to different extents by selenium availability. Increased amounts of selenoproteins observed in response to selenium supplementation were shown in several studies to correlate with increases in the corresponding mRNA levels. In general, selenoprotein levels in brain are less sensitive to dietary selenium fluctuation than the corresponding selenoprotein levels in other tissues.

The diverse role of selenium within selenoproteins: a review

Selenium functions within mammalian systems primarily in the form of selenoproteins. Selenoproteins contain selenium as selenocysteine and perform a variety of physiological roles. Eleven selenoproteins have been identified: cellular or classical glutathione peroxidase; plasma (or extracellular) glutathione peroxidase; phospholipid hydroperoxide glutathione peroxidase; gastrointestinal glutathione peroxidase; selenoprotein P; types 1, 2, and 3 iodothyronine deiodinase; selenoprotein W; thioredoxin reductase; and selenophosphate synthetase. Of these, cellular and plasma glutathione peroxidase are the functional parameters used for the assessment of selenium status. Glutathione peroxidases catalyze the reduction of peroxides that can cause cellular damage. Thioredoxin reductase provides reducing power for several biochemical processes and defends against oxidative stress. Selenoprotein P appears to play a role in oxidant defense. Selenoprotein W may play a role in oxidant defense and be involved with muscle metabolism. Thyroid deiodinases function in the formation and regulation of active thyroid hormone. Selenophosphate synthetase is an enzyme required for the incorporation of selenocysteine into selenoproteins. In addition, a protein in the sperm mitochondrial capsule, which is vital to the integrity of sperm flagella, may be a unique selenoprotein. Recommended intakes, food sources, and status assessment of selenium, as well as selenium's role in health and disease processes, are reviewed.

Mortality risk in selenium-deficient HIV-positive children

OBJECTIVE

To determine the independent contribution of specific nutritional factors on disease progression and survival in HIV-1-infected children.

POPULATION

HIV-infected children (N = 24), who were perinatally exposed to the virus and symptomatic, were recruited between October and December of 1990 from the Jackson Memorial Pediatric Immunology Clinic, Miami, Florida, and observed for 5 years.

METHODS

Immune status was measured by CD4 cell count; nutritional status was determined using serum albumin and plasma trace elements including iron, zinc, and selenium. Cox proportional hazards regression models were used to evaluate the relationship of these parameters to survival. Use of antiretroviral treatment was considered in the statistical model, and age at death was considered a parameter of disease progression.

RESULTS

Over the course of the study, 12 children died of HIV-related causes. The final Cox multivariate analysis indicated that, of the variables evaluated, only CD4 cell count below 200 (risk ratio [RR] = 7.05; 95% confidence interval [CI], 1.87-26.5); p = .004], and low levels of plasma selenium (RR = 5.96; 95% CI, 1.32-26.81; p = .02) were significantly and independently related to mortality. Among the children who died, those with low selenium levels (< or =85 microg/L), died at a younger age, suggesting more rapid disease progression.

CONCLUSIONS

In pediatric HIV-infection, low plasma level of selenium is an independent predictor of mortality, and appears to be associated with faster disease progression.

Micronutrients and the pathogenesis of human immunodeficiency virus infection

Micronutrient deficiencies may be common during human immunodeficiency virus (HIV) infection. Insufficient dietary intake, malabsorption, diarrhoea, and impaired storage and altered metabolism of micronutrients can contribute to the development of micronutrient deficiencies. Low plasma or serum levels of vitamins A, E, B6, B12 and C, carotenoids, Se, and Zn are common in many HIV-infected populations. Micronutrient deficiencies may contribute to the pathogenesis of HIV infection through increased oxidative stress and compromised immunity. Low levels or intakes of micronutrients such as vitamins A, E, B6 and B12, Zn and Se have been associated with adverse clinical outcomes during HIV infection, and new studies are emerging which suggest that micronutrient supplementation may help reduce morbidity and mortality during HIV infection.

Levels of major selenoproteins in T cells decrease during HIV infection and low molecular mass selenium compounds increase

It has been observed previously that plasma selenium and glutathione levels are subnormal in HIV-infected individuals, and plasma glutathione peroxidase activity is decreased. Under these conditions the survival rate of AIDS patients is reduced significantly. In the present study, using 75Se-labeled human Jurkat T cells, we show that the levels of four 75Se-containing proteins are lower in HIV-infected cell populations than in uninfected cells. These major selenoproteins migrated as 57-, 26-, 21-, and 15-kDa species on SDS/PAGE gels. In our earlier studies, the 57-kDa protein was purified from T cells and identified as a subunit of thioredoxin reductase. The 26- and 21-kDa proteins were identified in immunoblot assays as the glutathione peroxidase (cGPX or GPX1) subunit and phospholipid hydroperoxide glutathione peroxidase (PHGPX or GPX4), respectively. We recently purified the 15-kDa protein and characterized it as a selenoprotein of unknown function. In contrast to selenoproteins, low molecular mass [75Se]compounds accumulated during HIV infection and migrated as a diffuse band near the front of SDS/PAGE gels.

Trace element deficiency and toxicity

Trace elements are involved in enzymatic activities, immunological reactions, physiological mechanisms and carcinogenesis. Deficiency in some trace elements, such as iron and iodine, is still an important health problem, especially in developing countries. Some groups of individuals are more likely to develop trace element deficiency. The role of trace elements deficiency is suspected in various clinical situations and is now confirmed by well designed supplementation studies. Although toxicity of trace elements with clinical manifestations is rare, it has been observed that manganese toxicity may occur in patients receiving parenteral nutrition. Recent data about trace elements deficiency and toxicity are indicated in this review.

Dietary oxidative stress and the potentiation of viral infection

Oxidative stress is implicated in the pathogenesis of several viral infections, including hepatitis, influenza, and AIDS. Dietary oxidative stress due to either selenium or vitamin E deficiency increases cardiac damage in mice infected with a myocarditic strain of coxsackievirus B3. Such dietary oxidative stress also allows a normally benign (i.e., amyocarditic) coxsackievirus B3 to convert to virulence and cause heart damage. This conversion to virulence is due to a nucleotide sequence change in the genome of the benign virus, which then resembles more closely the nucleotide sequence of virulent strains. Although it has been known for many years that poor nutrition can affect host response to infection, this is the first report of host nutrition affecting the genetic sequence of a pathogen. Further research is needed to determine whether poor host nutrition plays any role in the emergence of new viral diseases via alterations in he genotype of an infectious agent.

Micronutrient status in relationship to mortality in HIV-1 disease

Selenium deficiency has been demonstrated to be a significant predictor of HIV-related mortality, independent of CD4 over time, CD4 < 200 at baseline, and antiretroviral treatment. Although selenium deficiency in healthy humans is relatively rare (Cohen et al. 1989, Lockitch, 1989), a number of studies have documented a decline in plasma selenium levels and decreased glutathione peroxidase activity in individuals with HIV/AIDS (Dworkin et al. 1988, Cirelli et al. 1991, Mantero-Atienza et al. 1991, Staal et al. 1992, Allavena et al. 1995). These findings are of particular concern in light of selenium's influence on immune function, viral replication, and survival. As recent investigations (Delmas-Beauvieux et al. 1996) indicate that supplementation with selenium may help to increase the enzymatic defense systems in HIV-infected patients, further studies to determine possible mechanisms and clinical trials to evaluate the effect of selenium supplementation on HIV disease progression are essential.

HIV-1 infection in women is associated with severe nutritional deficiencies

Nutritional deficiencies may contribute to immune dysregulation, and have been shown to be sensitive markers of HIV-1 disease progression. Only limited information exists, however, regarding the nutritional profile of HIV-1-seropositive drug abusers. Immune and nutritional measurements were obtained in a subsample of 125 subjects from a larger cohort of drug users being followed for HIV-1 infection and cofactors of disease progression. Nutritional deficiencies, particularly vitamins A, E, and zinc, were widespread with up to 86% of the drug users exhibiting at least one nutritional alteration. Although immune parameters (CD4 count, CD8 count, beta2-microglobulin) were similar in the HIV-1-infected men and women, women had significantly poorer overall nutritional status, as measured by plasma proteins, which are considered to be sensitive markers of malnutrition. A comparison of individuals with advanced disease (CD4 count <200/mm3) revealed significantly lower levels of plasma prealbumin (p < .01), selenium, (p < .05), and greater deficiency of vitamins A (p < .01) and E (p < .05) in women than in men. The greater severity of nutritional deficiencies noted in HIV-1-infected women may be an important determinant of disease progression and survival.