Zinc and human immunodeficiency virus infection

Paediatric HIV: Correlation between Serum Zinc Levels and CD4 Percentage on Asymptomatic Nigerian Children Living with HIV

OBJECTIVE

This study was conducted to determine the relationship between their serum zinc levels and the CD4% in a cohort children living with HIV.

METHODS

One hundred asymptomatic, anti-retroviral Therapy (ART) naïve children living with HIV (participants) aged 5-60 months who were enrolled into the Paediatric HIV clinic of The University of Nigeria Teaching Hospital were recruited in the study over a 10-month period. Blood samples were collected in the morning from non-fasting participants and serum zinc levels were analysed using Atomic Absorption Spectrophotometer. The CD4% was ascertained using the CD4% easy count kit on the Partec® Cyflow Counter machine. Data were analysed using Statistical Package for the Social Sciences version 19.

RESULT

The median (IQR) serum zinc level for the participants was 55.5 µg/dl (49.75) while their median (IQR) CD4% was 27.79% (18.67). Males had a median (IQR) CD4% of 24.29% (19.10) which was significantly lower than those of females [32% (20.59) (p = 0.047)]. No significant relationship was found between CD4% and zinc levels among the subjects (r = -0.061, p = 0.557).

CONCLUSION

Serum zinc levels of asymptomatic ART naïve children living with HIV have no relationship with their CD4%.

Determination of Elemental Composition of Malabar spinach, Lettuce, Spinach, Hyacinth Bean, and Cauliflower Vegetables Using Proton Induced X-Ray Emission Technique at Savar Subdistrict in Bangladesh

The concentrations of 18 different elements (K, Ca, Fe, Cl, P, Zn, S, Mn, Ti, Cr, Rb, Co, Br, Sr, Ru, Si, Ni, and Cu) were analyzed in five selected vegetables through Proton Induced X-ray Emission (PIXE) technique. The objective of this study was to provide updated information on concentrations of elements in vegetables available in the local markets at Savar subdistrict in Bangladesh. These elements were found in varying concentrations in the studied vegetables. The results also indicated that P, Cl, K, Ca, Mn, Fe, and Zn were found in all vegetables. Overall, K and Ca exhibited the highest concentrations. Cu and Ni exhibited the lowest concentrations in vegetables. The necessity of these elements was also evaluated, based on the established limits of regulatory standards. The findings of this study suggest that the consumption of these vegetables is not completely free of health risks.

Alternative divalent cations (Zn²⁺, Co²⁺, and Mn²⁺) are not mutagenic at conditions optimal for HIV-1 reverse transcriptase activity

BACKGROUND

Fidelity of DNA polymerases can be influenced by cation co-factors. Physiologically, Mg(2+) is used as a co-factor by HIV reverse transcriptase (RT) to perform catalysis; however, alternative cations including Mn(2+), Co(2+), and Zn(2+) can also support catalysis. Although Zn(2+) supports DNA synthesis, it inhibits HIV RT by significantly modifying RT catalysis. Zn(2+) is currently being investigated as a component of novel treatment options against HIV and we wanted to investigate the fidelity of RT with Zn(2+).

METHODS

We used PCR-based and plasmid-based alpha complementation assays as well as steady-state misinsertion and misincorporation assays to examine the fidelity of RT with Mn(2+), Co(2+), and Zn(2+).

RESULTS

The fidelity of DNA synthesis by HIV-1 RT was approximately 2.5 fold greater in Zn(2+) when compared to Mg(2+) at cation conditions optimized for nucleotide catalysis. Consistent with this, RT extended primers with mismatched 3' nucleotides poorly and inserted incorrect nucleotides less efficiently using Zn(2+) than Mg(2+). In agreement with previous literature, we observed that Mn(2+) and Co(2+) dramatically decreased the fidelity of RT at highly elevated concentrations (6 mM). However, surprisingly, the fidelity of HIV RT with Mn(2+) and Co(2+) remained similar to Mg(2+) at lower concentrations that are optimal for catalysis.

CONCLUSION

This study shows that Zn(2+), at optimal extension conditions, increases the fidelity of HIV-1 RT and challenges the notion that alternative cations capable of supporting polymerase catalysis are inherently mutagenic.

Zn deficiency in Brassica napus induces Mo and Mn accumulation associated with chloroplast proteins variation without Zn remobilization

The importance of zinc (Zn) has been of little concern in human nutrition despite a strong decrease of this element in crops since the rise of high yielding varieties. For better food quality, Zn biofortification can be used, but will be optimal only if mechanisms governing Zn management are better known. Using Zn deficiency, we are able to demonstrate that Zn is not remobilized in Brassica napus (B. napus). Thus, remobilization processes should not be targeted by biofortification strategies. This study also complemented previous work by investigating leaf responses to Zn deficiency, especially from proteomic and ionomic points of view, showing for example, an increase in Manganese (Mn) content and of the Mn-dependent protein, Oxygen Evolving Enhancer.

A Comparative Study of Selected Trace Element Content in Malay and Chinese Traditional Herbal Medicine (THM) Using an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS)

A total of 60 products of traditional herbal medicine (THM) in various dosage forms of herbal preparation were analyzed to determine selected trace elements (i.e., Zn, Mn, Cu, Cd, and Se) using ICP-MS. Thirty types of both Chinese and Malay THMs were chosen to represent each population. The closed vessel acid microwave digestion method, using CEM MARS 5, was employed for the extraction of the selected trace elements. The digestion method applied was validated by using certified reference material from the Trace Element in Spinach Leaves (SRM1570a). The recoveries of all elements were found to be in the range of 85.3%-98.9%. The results indicated that Zn, Mn, Cu, Cd and Se have their own trends of concentrations in all samples studied. The daily intake concentrations of the elements were in the following order: Mn > Zn > Cu > Se > Cd. Concentrations of all five elements were found to be dominant in Chinese THMs. The essentiality of the selected trace elements was also assessed, based on the recommended daily allowance (RDA), adequate intake (AI) and the United States Pharmacopeia (USP) for trace elements as reference. The concentrations of all elements studied were below the RDA, AI and USP values, which fall within the essential concentration range, except for cadmium.

Zinc adjunct therapy reduces case fatality in severe childhood pneumonia: a randomized double blind placebo-controlled trial

BACKGROUND

Pneumonia is a leading cause of children's deaths in developing countries and hinders achievement of the fourth Millennium Development Goal. This goal aims to reduce the under-five mortality rate, by two thirds, between 1990 and 2015.Few studies have examined the impact of zinc adjunct therapy on the outcome of childhood pneumonia. We determined the effect of zinc as adjunct therapy on time to normalization of respiratory rate, temperature and oxygen saturation. We also studied the effect of zinc adjunct therapy on case fatality of severe childhood pneumonia (as a secondary outcome) in Mulago Hospital, Uganda.

METHODS

In this double blind, randomized, placebo-controlled clinical trial, 352 children aged 6 to 59 months, with severe pneumonia were randomized to zinc (20 mg for children ≥ 12 months, and 10 mg for those < 12 months) or a placebo once daily for seven days, in addition to standard antibiotics for severe pneumonia. Children were assessed every six hours. Oxygen saturation was normal if it was above 92% (breathing room air) for more than 15 minutes. The respiratory rate was normal if it was consistently (more than 24 hours) below 50 breaths per minute in infants and 40 breaths per minute in children above 12 months of age. Temperature was normal if consistently below 37.5°C. The difference in case fatality was expressed by the risk ratio between the two groups.

RESULTS

Time to normalization of the respiratory rate, temperature and oxygen saturation was not significantly different between the two arms.Case fatality was 7/176 (4.0%) in the zinc group and 21/176 (11.9%) in the placebo group: Relative Risk 0.33 (95% CI 0.15 to 0.76). Relative Risk Reduction was 0.67 (95% CI 0.24 to 0.85), while the number needed to treat was 13. Among HIV infected children, case fatality was higher in the placebo (7/27) than in the zinc (0/28) group; RR 0.1 (95% CI 0.0, 1.0).Among 127 HIV uninfected children receiving the placebo, case fatality was 7/127 (5.5%); versus 5/129 (3.9%) among HIV uninfected group receiving zinc: RR 0.7 (95% CI 0.2, 2.2). The excess risk of death attributable to the placebo arm (Absolute Risk Reduction or ARR) was 8/100 (95% CI: 2/100, 14/100) children. This excess risk was substantially greater among HIV positive children than in HIV negative children (ARR: 26 (95% CI: 9, 42) per 100 versus 2 (95% CI: -4, 7) per 100); P-value for homogeneity of risk differences = 0.006.

CONCLUSION

Zinc adjunct therapy for severe pneumonia had no significant effect on time to normalization of the respiratory rate, temperature and oxygen saturation. However, zinc supplementation in these children significantly decreased case fatality.The difference in case fatality attributable to the protective effect of zinc therapy was greater among HIV infected than HIV uninfected children. Given these results, zinc could be considered for use as adjunct therapy for severe pneumonia, especially among Highly Active Antiretroviral Therapynaïve HIV infected children in our environment.

CLINICAL TRIALS REGISTRATION NUMBER

clinicaltrials.gov NCT00373100.

Mechanism of HIV reverse transcriptase inhibition by zinc: formation of a highly stable enzyme-(primer-template) complex with profoundly diminished catalytic activity

Several physiologically relevant cations including Ca(2+), Mn(2+), and Zn(2+) have been shown to inhibit HIV reverse transcriptase (RT), presumably by competitively displacing one or more Mg(2+) ions bound to RT. We analyzed the effects of Zn(2+) on reverse transcription and compared them to Ca(2+) and Mn(2+). Using nucleotide extension efficiency as a readout, Zn(2+) showed significant inhibition of reactions with 2 mM Mg(2+), even when present at only ∼5 μM. Mn(2+) and Ca(2+) were also inhibitory but at higher concentrations. Both Mn(2+) and Zn(2+) (but not Ca(2+)) supported RT incorporation in the absence of Mg(2+) with Mn(2+) being much more efficient. The maximum extension rates with Zn(2+), Mn(2+), and Mg(2+) were ∼0.1, 1, and 3.5 nucleotides per second, respectively. Zinc supported optimal RNase H activity at ∼25 μM, similar to the optimal for nucleotide addition in the presence of low dNTP concentrations. Surprisingly, processivity (average number of nucleotides incorporated in a single binding event with enzyme) during reverse transcription was comparable with Zn(2+) and Mg(2+), and single RT molecules were able to continue extension in the presence of Zn(2+) for several hours on the same template. Consistent with this result, the half-life for RT-Zn(2+)-(primer-template) complexes was 220 ± 60 min and only 1.7 ± 1 min with Mg(2+), indicating ∼130-fold more stable binding with Zn(2+). Essentially, the presence of Zn(2+) promotes the formation of a highly stable slowly progressing RT-(primer-template) complex.

Improved appetite after multi-micronutrient supplementation for six months in HIV-infected South African children

The aim of the study was to assess the effect of multi-micronutrient supplementation on the appetite of HIV-infected children. HIV-infected children (6-24 months) who had previously been hospitalized were enrolled into a double-blind randomized trial, and given daily multi-micronutrient supplements or placebos for six months. Appetite tests were performed at enrollment and after three and six months. Appetite was measured as ad libitum intake of a commercial cereal test food served after an overnight fast according to standardized procedures. Body weights and total amount of test food eaten were measured. In total, 99 children completed the study (50 on supplements and 49 on placebos). Amounts eaten per kilogram body weight in the supplement group at enrollment and after six months were 36.7+/-17.7 g/kg (mean+/-SD) and 41.3+/-15.0 g/kg respectively, while the amounts in the placebo group were 47.1+/-14.9 g/kg and 45.7+/-13.1g/kg respectively. The change in amount eaten per kilogram body weight over six months was significantly higher in the supplement group (4.7+/-14.7 g/kg) than in the placebo group (-1.4+/-15.1g/kg). Multi-micronutrient supplementation for six months seems to significantly improve the appetite of HIV-infected children.

Care and treatment of HIV-infected children in Africa: issues and challenges at the district hospital level

More than 90% of pediatric HIV infection occurs in sub-Saharan Africa and 75% of these children currently die before their fifth birthday. Most HIV-infected children in Africa rely on district hospitals for HIV treatment, but insufficient attention has been paid to improving HIV/AIDS care at this level. Considerable confusion exists about optimal use of combination antiretroviral treatment, prophylaxis for opportunistic infections and other rational healthcare interventions that can greatly improve the quality of life for these children. A simple and inexpensive infant HIV diagnostic assay and alternative laboratory markers of pediatric HIV disease progression would be highly beneficial. Routine anthropometric and neurodevelopmental assessments could help guide initiation and monitoring of antiretroviral therapy. Even in the absence of antiretroviral therapy, interventions such as immunizations, provision of micronutrients and nutrition counseling, prevention and treatment of opportunistic as well as endemic infections (such as helminths and malaria) can substantially reduce pediatric HIV-related morbidity and mortality. The need for pain relief, palliative care, counseling and emotional support is often underestimated. Surmounting the sense of hopelessness by providing district healthcare workers with training in basic pediatric HIV/AIDS care is an urgent priority.

Micronutrient levels and HIV disease status in HIV-infected patients on highly active antiretroviral therapy in the Nutrition for Healthy Living cohort

BACKGROUND

Low serum micronutrient levels were common before widespread use of highly active antiretroviral therapy (HAART) and were associated with adverse outcomes. Few data are available on micronutrient levels in subjects taking HAART.

OBJECTIVE

To determine the prevalence of low serum retinol, alpha-tocopherol, zinc, and selenium in HIV-infected subjects taking HAART and to assess the association of micronutrient levels with HIV disease status.

DESIGN

Cross-sectional.

SETTING

Nutrition for Healthy Living (NFHL) study.

PARTICIPANTS

HIV-infected subjects on HAART.

METHODS

Retinol, alpha-tocopherol, zinc, and selenium were determined in frozen serum samples from 171 men and 117 women. Low serum levels were defined as retinol <30 microg/dL, selenium <85 microg/L, alpha-tocopherol <500 microg/dL, and zinc <670 microg/L. Association of micronutrient quartiles with CD4 cell count, CD4 count <200 cells/mm, HIV viral load (VL), and undetectable VL was assessed using adjusted multivariate regression.

RESULTS

Five percent of men and 14% of women had low retinol, 8% of men and 3% of women had low selenium, and 7% of men and no women had low alpha-tocopherol. Forty percent of men and 36% of women had low zinc, however. Subjects in the upper quartiles of zinc had lower log VL levels than those in the lowest quartile (significant for women). Subjects in the upper quartiles of selenium also tended to have lower VL levels compared with those in the lowest quartile. Surprisingly, women in the upper quartiles of retinol had higher log VLs than those in the lowest quartile. There was no significant association of any micronutrient with CD4 cell count or likelihood of CD4 count <200 cells/mm. The level of CD4 cell count influenced the association of retinol with log VL in men, however. In men with CD4 counts >350 cells/mm, those with higher retinol had higher log VLs compared with the lowest quartile, whereas in men with CD4 counts <350, those with higher retinol levels had lower log VLs compared with the lowest quartile.

CONCLUSIONS

Low retinol, alpha-tocopherol, and selenium are uncommon in HIV-infected subjects on HAART. Zinc deficiency remains common, however. Decreased retinol levels in women and in men with CD4 counts >350 cells/mm and increased zinc and selenium levels in both genders may be associated with improved virologic control.

Safety and efficacy of zinc supplementation for children with HIV-1 infection in South Africa: a randomised double-blind placebo-controlled trial

BACKGROUND

Zinc deficiency is associated with impaired immune function and an increased risk of infection. Supplementation can decrease the incidence of diarrhoea and pneumonia in children in resource-poor countries. However, in children with HIV-1 infection, the safety of zinc supplementation is uncertain. We aimed to assess the role of zinc in HIV-1 replication before mass zinc supplementation is recommended in regions of high HIV-1 prevalence.

METHODS

We did a randomised double-blind placebo-controlled equivalence trial of zinc supplementation at Grey's Hospital in Pietermaritzburg, South Africa. 96 children with HIV-1 infection were randomly assigned to receive 10 mg of elemental zinc as sulphate or placebo daily for 6 months. Baseline measurements of plasma HIV-1 viral load and the percentage of CD4+ T lymphocytes were established at two study visits before randomisation, and measurements were repeated 3, 6, and 9 months after the start of supplementation. The primary outcome measure was plasma HIV-1 viral load. Analysis was per protocol.

FINDINGS

The mean log(10) HIV-1 viral load was 5.4 (SD 0.61) for the placebo group and 5.4 (SD 0.66) for the zinc-supplemented group 6 months after supplementation began (difference 0.0002, 95% CI -0.27 to 0.27). 3 months after supplementation ended, the corresponding values were 5.5 (SD 0.77) and 5.4 (SD 0.61), a difference of 0.05 (-0.24 to 0.35). The mean percentage of CD4+ T lymphocytes and median haemoglobin concentrations were also similar between the two groups after zinc supplementation. Two deaths occurred in the zinc supplementation group and seven in the placebo group (p=0.1). Children given zinc supplementation were less likely to get watery diarrhoea than those given placebo. Watery diarrhoea was diagnosed at 30 (7.4%) of 407 clinic visits in the zinc-supplemented group versus 65 (14.5%) of 447 visits in the placebo group (p=0.001).

INTERPRETATION

Zinc supplementation of HIV-1-infected children does not result in an increase in plasma HIV-1 viral load and could reduce morbidity caused by diarrhoea.

RELEVANCE TO PRACTICE

Programmes to enhance zinc intake in deficient populations with a high prevalence of HIV-1 infection can be implemented without concern for adverse effects on HIV-1 replication. In view of the reductions in diarrhoea and pneumonia morbidity, zinc supplementation should be used as adjunct therapy for children with HIV-1 infection.

Zinc and the risk for infectious disease

Zinc is an essential micronutrient for human growth, development, and immune function. Zinc deficiency impairs overall immune function and resistance to infection. Mild to moderate zinc deficiency can be best detected through a positive response to supplementation trials. Zinc supplementation has been shown to have a positive effect on the incidence of diarrhea (18% reduction, 95% CI: 7-28%) and pneumonia (41% reduction, 95% CI: 17-59%), and might lead to a decrease in the incidence of malaria. Zinc has also proven to decrease the duration of diarrhea by 15% (95% CI: 5-24%). Maternal zinc supplementation may lead to a decrease in infant infections. Studies assessing the role of zinc supplementation among persons with HIV, tuberculosis, and the common cold have not been conclusive. Two studies have shown zinc supplementation to decrease child mortality by more than 50%. Zinc clearly has an important role in infant and childhood infectious diseases; programs to increase the intake of zinc among deficient populations are needed.

Trace elements and host defense: recent advances and continuing challenges

Although it is widely recognized that essential trace elements are required for the differentiation, activation and performance of numerous functions of immune cells, the specific roles of these inorganic micronutrients in these processes remain largely undefined. New insights about the participation of zinc, iron and copper in the selection, maturation and early activation events of the immune cells have been gained by judicious use of available tools in analytical cell biology, molecular genetics and array technology. Also, randomly controlled clinical and community trials demonstrate that zinc supplementation can enhance immunocompetence and decrease the incidence and severity of some infections in individuals with diagnosed or suspected mild zinc deficiency. These exciting results provide an impetus to evaluate the potential benefits of supplementation programs for individuals and groups with suboptimal trace element status as a cost-effective means of reducing the risk of infectious diseases.