Promotion of Anti-Tuberculosis Macrophage Activity by L-Arginine in the Absence of Nitric Oxide.

Macrophages are indispensable immune cells tasked at eliminating intracellular pathogens. Mycobacterium tuberculosis (Mtb), one of the most virulent intracellular bacterial pathogens known to man, infects and resides within macrophages. While macrophages can be provoked by extracellular stimuli to inhibit and kill Mtb bacilli, these host defense mechanisms can be blocked by limiting nutritional metabolites, such as amino acids. The amino acid L-arginine has been well described to enhance immune function, especially in the context of driving macrophage nitric oxide (NO) production in mice. In this study, we aimed to establish the necessity of L-arginine on anti-Mtb macrophage function independent of NO. Utilizing an in vitro system, we identified that macrophages relied on NO for only half of their L-arginine-mediated host defenses and this L-arginine-mediated defense in the absence of NO was associated with enhanced macrophage numbers and viability. Additionally, we observed macrophage glycolysis to be driven by both L-arginine and mechanistic target of rapamycin (mTOR), and inhibition of glycolysis or mTOR reduced macrophage control of Mtb as well as macrophage number and viability in the presence of L-arginine. Our data underscore L-arginine as an essential nutrient for macrophage function, not only by fueling anti-mycobacterial NO production, but also as a central regulator of macrophage metabolism and additional host defense mechanisms.

Vitamin D supplementation in respiratory diseases: evidence from randomized controlled trials.

Pulmonary diseases are one of the most important causes of morbidity and mortality. Although vitamin D is best known for its role in calcium, phosphorus, and bone homeostasis, it has gained attention in the recent years because of a wide range of extraskeletal effects, including its immunomodulatory and antibacterial potential. Vitamin D deficiency is highly prevalent in chronic pulmonary diseases such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, tuberculosis, and asthma, and several clinical studies have been conducted investigating the effect of vitamin D supplementation on disease outcomes. In this review, we searched for positive evidence on vitamin D supplementation from randomized controlled trials and elaborated on the optimal serum vitamin D levels and dosing regimens for an effective intervention. While vitamin D supplementation seems to be beneficial as an add­on treatment for adult patients with asthma and a potent intervention to reduce exacerbations in patients with COPD, there is little evidence for its therapeutic use in cystic fibrosis, pneumonia, and tuberculosis.

Recent advancements in the development of anti-tuberculosis drugs.

Modern chemotherapy has significantly improved patient outcomes against drug-sensitive tuberculosis. However, the rapid emergence of drug-resistant tuberculosis, together with the bacterium's ability to persist and remain latent present a major public health challenge. To overcome this problem, research into novel anti-tuberculosis targets and drug candidates is thus of paramount importance. This review article provides an overview of tuberculosis highlighting the recent advances and tools that are employed in the field of anti-tuberculosis drug discovery. The predominant focus is on anti-tuberculosis agents that are currently in the pipeline, i.e. clinical trials.

Nutritional supplements for people being treated for active tuberculosis.

BACKGROUND: Tuberculosis and malnutrition are linked in a complex relationship. Tuberculosis may cause undernutrition through increased metabolic demands and decreased intake, and nutritional deficiencies may worsen the disease, or delay recovery by depressing important immune functions. At present, there is no evidence-based nutritional guidance for adults and children being treated for tuberculosis. OBJECTIVES: To assess the effects of oral nutritional supplements in people being treated with antituberculous drug therapy for active tuberculosis. SEARCH METHODS: We searched the Cochrane Infectious Disease Group Specialized Register, Cochrane Central Register of Controlled Trials (CENTRAL; Issue 1, 2016), MEDLINE (from 1946 to 4 February 2016), EMBASE (from 1980 to 4 February 2016), LILACS (from 1982 to 4 February 2016), the metaRegister of Controlled Trials (mRCT), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), and the Indian Journal of Tuberculosis up to 4 February 2016, and checked the reference lists of all included studies. SELECTION CRITERIA: Randomized controlled trials that compared any oral nutritional supplement given for at least four weeks with no nutritional intervention, placebo, or dietary advice only for people being treated for active tuberculosis. The primary outcomes of interest were all-cause death, and cure at six and 12 months. DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials for inclusion, and extracted data and assessed the risk of bias in the included trials. We presented the results as risk ratios (RR) for dichotomous variables, and mean differences (MD) for continuous variables, with 95% confidence intervals (CIs). Where appropriate, we pooled data from trials with similar interventions and outcomes. We assessed the quality of the evidence using the Grading of Recommendation Assessment, Development and Evaluation (GRADE) approach. MAIN RESULTS: Thirty-five trials, including 8283 participants, met the inclusion criteria of this review. Macronutrient supplementationSix trials assessed the provision of free food, or high-energy supplements. Only two trials measured total dietary intake, and in both trials the intervention increased calorie consumption compared to controls.The available trials were too small to reliably prove or exclude clinically important benefits on mortality (RR 0.34, 95% CI 0.10 to 1.20; four trials, 567 participants, very low quality evidence), cure (RR 0.91, 95% CI 0.59 to 1.41; one trial, 102 participants, very low quality evidence), or treatment completion (data not pooled; two trials, 365 participants, very low quality evidence).Supplementation probably produces a modest increase in weight gain during treatment for active tuberculosis, although this was not seen consistently across all trials (data not pooled; five trials, 883 participants, moderate quality evidence). Two small studies provide some evidence that quality of life may also be improved but the trials were too small to have much confidence in the result (data not pooled; two trials, 134 participants, low quality evidence). Micronutrient supplementationSix trials assessed multi-micronutrient supplementation in doses up to 10 times the dietary reference intake, and 18 trials assessed single or dual micronutrient supplementation.Routine multi-micronutrient supplementation may have little or no effect on mortality in HIV-negative people with tuberculosis (RR 0.86, 95% CI 0.46 to 1.6; four trials, 1219 participants, low quality evidence), or HIV-positive people who are not taking antiretroviral therapy (RR 0.92, 95% CI 0.69 to 1.23; three trials, 1429 participants, moderate quality evidence). There is insufficient evidence to know if supplementation improves cure (no trials), treatment completion (RR 0.99, 95% CI 0.95 to 1.04; one trial, 302 participants, very low quality evidence), or the proportion of people who remain sputum positive during the first eight weeks (RR 0.92, 95% CI 0.63 to 1.35; two trials, 1020 participants, very low quality evidence). However, supplementation may have little or no effect on weight gain during treatment (data not pooled; five trials, 2940 participants, low quality evidence), and no studies have assessed the effect on quality of life.Plasma levels of vitamin A appear to increase following initiation of tuberculosis treatment regardless of supplementation. In contrast, supplementation probably does improve plasma levels of zinc, vitamin D, vitamin E, and selenium, but this has not been shown to have clinically important benefits. Of note, despite multiple studies of vitamin D supplementation in different doses, statistically significant benefits on sputum conversion have not been demonstrated. AUTHORS' CONCLUSIONS: There is currently insufficient research to know whether routinely providing free food, or energy supplements improves tuberculosis treatment outcomes, but it probably improves weight gain in some settings.Although blood levels of some vitamins may be low in people starting treatment for active tuberculosis, there is currently no reliable evidence that routinely supplementing above recommended daily amounts has clinical benefits.

Nutrición y tuberculosis. Síntesis de la guía OMS, la atención y apoyo nutricional a pacientes con tuberculosis / Nutrition and tuberculosis. Synthesis of the guide WHO, the attention and nutritional support to patients with tuberculosis

El presente artículo es una síntesis de la Guía “La atención y apoyo nutricional a pacientes con tuberculosis” complementada con aspectos relativos de otras guías y documentos similares, que proporcionan orientación sobre los principios y recomendaciones para la atención y el apoyo nutricional de los pacientes con tuberculosis (TB) como parte de su cuidado regular. La guía en mención ha sido elaborada por la Organización Mundial de la Salud (OMS) a pedido de los países miembros y está dirigida al personal de salud que brinda tratamiento integral a personas con TB en los establecimientos de salud. El objetivo de este artículo es presentar una síntesis de los principales aspectos a considerar en la atención nutricional y su evaluación.

This article is a summary of the guide “The nutritional care and support to patients with tuberculosis” supplemented with related aspects of other guides and similar documents that provide guidance on the principles and recommendations for nutritional care and support of patients with tuberculosis (TB) as part of their regular care. The guide in question has been produced by the World Health Organization (WHO) at the request of member countries and is run health staff provides comprehensive treatment to people with TB in health facilities. The aim of this article is to present a summary of the main aspects to consider in nutritional care and evaluation.

Nutritional supplementation: the additional costs of managing children infected with HIV in resource-constrained settings.

OBJECTIVE: To explore the financial implications of applying the WHO guidelines for the nutritional management of HIV-infected children in a rural South African HIV programme. METHODS: WHO guidelines describe Nutritional Care Plans (NCPs) for three categories of HIV-infected children: NCP-A: growing adequately; NCP-B: weight-for-age z-score (WAZ) ≤-2 but no evidence of severe acute malnutrition (SAM), confirmed weight loss/growth curve flattening, or condition with increased nutritional needs (e.g. tuberculosis); NCP-C: SAM. In resource-constrained settings, children requiring NCP-B or NCP-C usually need supplementation to achieve the additional energy recommendation. We estimated the proportion of children initiating antiretroviral treatment (ART) in the Hlabisa HIV Programme who would have been eligible for supplementation in 2010. The cost of supplying 26-weeks supplementation as a proportion of the cost of supplying ART to the same group was calculated. RESULTS: A total of 251 children aged 6 months to 14 years initiated ART. Eighty-eight required 6-month NCP-B, including 41 with a WAZ ≤-2 (no evidence of SAM) and 47 with a WAZ >-2 with co-existent morbidities including tuberculosis. Additionally, 25 children had SAM and required 10-weeks NCP-C followed by 16-weeks NCP-B. Thus, 113 of 251 (45%) children were eligible for nutritional supplementation at an estimated overall cost of $11 136, using 2010 exchange rates. These costs are an estimated additional 11.6% to that of supplying 26-week ART to the 251 children initiated. CONCLUSIONS: It is essential to address nutritional needs of HIV-infected children to optimise their health outcomes. Nutritional supplementation should be integral to, and budgeted for, in HIV programmes.

Guideline: nutritional care and support for patients with tuberculosis

This guideline provides guidance on the principles and evidence-informed recommendations on the nutritional care and support for patients with tuberculosis. Undernutrition increases the risk of tuberculosis and in turn tuberculosis can lead to malnutrition. Undernutrition is therefore highly prevalent among people with tuberculosis. It has been demonstrated that undernutrition is a risk factor for progression from tuberculosis infection to active tuberculosis disease and that undernutrition at the time of diagnosis of active tuberculosis is a predictor of increased risk of death and tuberculosis relapse. However, the evidence concerning the effect of nutritional supplementation on tuberculosis prevention and health outcomes among people with tuberculosis had not previously been systematically reviewed. Member States have requested guidance from the World Health Organization (WHO) on nutritional care and support for patients with tuberculosis. Evidence: The primary audience for the guideline is health workers providing care to people with tuberculosis. However, the guideline is also intended for a wider audience including policy-makers, their expert advisers, and technical and programme staff at organizations involved in the design, implementation and scaling-up of nutrition actions for public health.

Nutritional supplements for people being treated for active tuberculosis.

BACKGROUND: Tuberculosis and malnutrition are linked in a complex relationship. The infection may cause undernutrition through increased metabolic demands and decreased intake, and nutritional deficiencies may worsen the disease, or delay recovery by depressing important immune functions. At present, there are no evidence-based nutritional guidance for adults and children being treated for tuberculosis. OBJECTIVES: To assess the effects of oral nutritional supplements (food, protein/energy supplements or micronutrients) on tuberculosis treatment outcomes and recovery in people on antituberculous drug therapy for active tuberculosis. SEARCH METHODS: We searched the Cochrane Infectious Disease Group Specialized Register, CENTRAL (The Cochrane Library), MEDLINE, EMBASE, LILACS, mRCT, and the Indian Journal of Tuberculosis to July 2011, and checked the reference lists of all included studies. SELECTION CRITERIA: Randomized controlled trials comparing any oral nutritional supplement given for at least four weeks with no nutritional intervention, placebo, or dietary advice only for people being treated for active tuberculosis. DATA COLLECTION AND ANALYSIS: Two authors independently selected trials, extracted data, and assessed the risk of bias. Results are presented as risk ratios (RR) for dichotomous variables, and mean differences (MD) for continuous variables, with 95% confidence intervals (CI). Where appropriate, data from trials with similar interventions and outcomes have been pooled. The quality of evidence was assessed using the GRADE methods. MAIN RESULTS: Twenty-three trials, with 6842 participants, were included. Macronutrient supplementation Five trials assessed the provision of free food, or high energy supplements, although none were shown to provide a total daily kilocalorie intake above the current daily recommended intake for the non-infected population.The available trials were too small to reliably prove or exclude clinically important benefits on mortality, cure, or treatment completion. One small trial from India did find a statistically significant benefit on treatment completion, and clearance of the bacteria from the sputum, but these findings have not been confirmed in larger trials elsewhere (VERY LOW quality evidence).The provision of free food or high-energy nutritional products probably does produce a modest increase in weight gain during treatment for active tuberculosis (MODERATE quality evidence). Two small studies provide some evidence that physical function and quality of life may also be improved but the trials were too small to have much confidence in the result (LOW quality evidence). These effects were not seen in the one trial which included only human immunodeficiency virus (HIV)-positive patients.Micronutrient supplementation Five trials assessed multi-micronutrient supplementation in doses up to ten times the dietary reference intake, and 12 trials assessed single or dual micronutrient supplementation.There is insufficient evidence to judge whether multi-micronutrients have a beneficial effect on mortality in HIV- negative patients with tuberculosis (VERY LOW quality evidence), but the available studies show that multi-micronutrients probably have little or no effect on mortality in HIV-positive patients with tuberculosis (MODERATE quality evidence). No studies have assessed the effects of multi-micronutrients on cure, or treatment completion.Multi-micronutrient supplements may have little or no effect on the proportion of tuberculosis patients remaining sputum positive during the first eight weeks (LOW quality evidence), and probably have no effect on weight gain during treatment (MODERATE quality evidence). No studies have assessed quality of life.Plasma levels of vitamin A appear to increase following initiation of tuberculosis treatment regardless of supplementation. In contrast, plasma levels of zinc, vitamin D and E, and selenium may be improved by supplementation during the early stages of tuberculosis treatment, but a consistent benefit on tuberculosis treatment outcomes or nutritional recovery has not been demonstrated. AUTHORS' CONCLUSIONS: There is insufficient research to know whether routinely providing free food or energy supplements results in better tuberculosis treatment outcomes, or improved quality of life. Further trials, particularly from food insecure settings, should have adequate sample sizes to identify, or exclude, clinically important benefits.Although blood levels of some vitamins may be low in patients starting treatment for active tuberculosis, there is currently no reliable evidence that routinely supplementing at or above recommended daily amounts has clinical benefits.

Pilot randomized trial of nutritional supplementation in patients with tuberculosis and HIV-tuberculosis coinfection receiving directly observed short-course chemotherapy for tuberculosis.

OBJECTIVE: To investigate the effects of nutritional supplementation on the outcome and nutritional status of south Indian patients with tuberculosis (TB) with and without human immunodeficiency virus (HIV) coinfection on anti-tuberculous therapy. METHOD: Randomized controlled trial on the effect of a locally prepared cereal-lentil mixture providing 930 kcal and a multivitamin micronutrient supplement during anti-tuberculous therapy in 81 newly diagnosed TB alone and 22 TB-HIV-coinfected patients, among whom 51 received and 52 did not receive the supplement. The primary outcome evaluated at completion of TB therapy was outcome of TB treatment, as classified by the national programme. Secondary outcomes were body composition, compliance and condition on follow-up 1 year after cessation of TB therapy and supplementation. RESULTS: There was no significant difference in TB outcomes at the end of treatment, but HIV-TB coinfected individuals had four times greater odds of poor outcome than those with TB alone. Among patients with TB, 1/35 (2.9%) supplemented and 5/42(12%) of those not supplemented had poor outcomes, while among TB-HIV-coinfected individuals, 4/13 (31%) supplemented and 3/7 (42.8%) non-supplemented patients had poor outcomes at the end of treatment, and the differences were more marked after 1 year of follow-up. Although there was some trend of benefit for both TB alone and TB-HIV coinfection, the results were not statistically significant at the end of TB treatment, possibly because of limited sample size. CONCLUSION: Nutritional supplements in patients are a potentially feasible, low-cost intervention, which could impact patients with TB and TB-HIV. The public health importance of these diseases in resource-limited settings suggests the need for large, multi-centre randomized control trials on nutritional supplementation.

Daily multi-micronutrient supplementation during tuberculosis treatment increases weight and grip strength among HIV-uninfected but not HIV-infected patients in Mwanza, Tanzania.

Undernutrition is common among tuberculosis (TB) patients. The objective of this study was to assess the effect of multi-micronutrient supplementation during TB treatment on weight, body composition, and handgrip strength. A total of 865 patients with smear-positive (PTB+) or -negative (PTB-) pulmonary TB were randomly allocated to receive a daily biscuit with or without multi-micronutrients for 60 d during the intensive phase of TB treatment. Weight, arm fat area, arm muscle area, and handgrip strength were assessed at baseline and after 2 and 5 mo. At 2 mo, the multi-micronutrient supplementation led to a higher handgrip gain (1.22 kg; 95% CI = 0.50, 1.94; P = 0.001) but had no effects on other outcomes. The effects of multi-micronutrient supplementation were modified by HIV infection (P-interaction = 0.002). Among HIV- patients, multi-micronutrient supplementation increased weight gain by 590 g (95% CI = -40, 1210; P = 0.07) and handgrip strength by 1.6 kg (95% CI = 0.78, 2.47; P < 0.001), whereas among HIV+ patients, it reduced weight gain by 1440 g (95% CI = 290, 2590; P = 0.002) and had no effect on handgrip strength (0.07 kg; 95% CI = -1.30, 1.46; P = 0.91). The reduced weight gain among HIV+ patients receiving multi-micronutrient supplementation seemed to be explained by a higher proportion of patients reporting fever. At 5 mo, the effects on weight were sustained, whereas there was no effect on handgrip strength. In conclusion, multi-micronutrient supplementation given as a biscuit is beneficial among HIV- PTB patients and may be recommended to TB programs. More research is needed to develop an effective supplement for HIV+ PTB patients.

Vitamin D and host resistance to infection? Putting the cart in front of the horse.

Vitamin D is being touted as an anti-infective agent and it has even been suggested that vitamin D supplementation could be effective against the H1N1 influenza virus. The claims are largely based on the ability of vitamin D to induce antibacterial peptides and evidence that the immune system produces active vitamin D (1,25(OH)(2)D(3)) in situ. While there are many examples of immune production of 1,25(OH)(2)D(3) in vitro, there is little in vivo evidence. In addition, it is not clear what role immune production of 1,25(OH)(2)D(3) has on the course of disease. Vitamin D and 1,25(OH)(2)D(3) inhibit T helper type 1 (Th1)/Th17-mediated immune responses and autoimmune diseases by acting on the innate and acquired immune system to inhibit the function of Th1 and Th17 cells. Th1 and Th17 cells are important in host resistance to many infections including tuberculosis (TB) caused by Mycobacterium tuberculosis. Paradoxically the innate immune system is induced to produce antibacterial peptides that are effective against TB in vitro. Data from several models of infection have so far not supported a role for vitamin D in affecting the course of disease. There is also very little evidence that vitamin D affects the course of human TB infection. Experiments have not been done in cells, mice or humans to evaluate the effect of vitamin D on influenza virus. At this time it would be premature to claim that vitamin D has an effect on TB, influenza or any other infection.

Trick-or-treat: dietary lipids and host resistance to infectious disease.

The increased intake of omega-6 fatty acids together with the widely use of omega-3 supplements in Western diets can affect the host defence against infectious diseases. In the present review we focused on the impact of these fatty acids on salmonella and mycobacteria infection models in animals or in cell cultures. Particular attention was given to the molecular mechanisms involved.

Nutritional supplements for people being treated for active tuberculosis.

BACKGROUND: Tuberculosis is a serious infection affecting mainly the lungs. It may contribute to nutritional deficiencies which in turn may delay recovery by depressing immune functions. Nutritional supplements might therefore promote recovery in people being treated for tuberculosis. OBJECTIVES: To assess the provision of oral nutritional supplements to promote the recovery of people being treated with antituberculous drug therapy for active tuberculosis. SEARCH STRATEGY: We searched the Cochrane Infectious Disease Group Specialized Register (June 2008), CENTRAL (The Cochrane Library 2008, Issue 2), MEDLINE (June 2008), EMBASE (June 2008), LILACS (June 2008), mRCT (June 2008), the Indian Journal of Tuberculosis (1983 to June 2008), and checked the reference lists of all included studies. SELECTION CRITERIA: Randomized controlled trials comparing any oral nutritional supplement given for at least four weeks with no nutritional intervention, placebo, or dietary advice only for people being treated for active tuberculosis. DATA COLLECTION AND ANALYSIS: Two authors independently selected trials, extracted data, and assessed risk of bias. We calculated risk ratios (RR) for dichotomous variables and mean differences (MD) for continuous variables, with 95% confidence intervals (CI). We pooled data from trials with similar interventions and outcomes. MAIN RESULTS: Twelve trials (3393 participants) were included. Five trials had adequate allocation concealment. Interventions included a high energy supplement, high cholesterol diet, vitamin D, vitamin A, zinc, arginine, multiple micronutrient supplements, combined multiple micronutrient supplements and zinc, combined vitamin A and zinc, and combined vitamin A and selenium. The following supplements were associated with increased body weight at follow up: high energy supplements (MD 1.73 kg, 95% CI 0.81 to 2.65; 34 participants, 1 trial); multiple micronutrients plus additional zinc (MD 2.37 kg, 95% CI 2.21 to 2.53; 192 participants, 1 trial); and vitamin A plus zinc (MD 3.10 kg, 95% CI 0.74 to 5.46; 80 participants, 1 trial). There was no evidence that any supplement affected the number of deaths or number of participants with sputum test positive results at the end of treatment. AUTHORS' CONCLUSIONS: There is limited evidence that high energy supplements and some combinations of zinc with other micronutrients may help people with tuberculosis to gain weight. There is not enough evidence to assess the effect of other combinations of nutrients. A number of relevant trials are in progress, and, where appropriate, the results will be incorporated into future updates of this review.

Indications for percutaneous endoscopic gastrostomy in complex tuberculosis patients.

OBJECTIVES: Percutaneous endoscopic gastrostomy (PEG) is a widely used method for providing long-term administration of tube feeding. Different indications in relation to diseases, impairments and nutritional factors for PEG placement have been mentioned in guidelines. Treatment with PEG has not been described previously for tuberculosis (TB). Our aim was to identify and describe indications and contributing factors for PEG placement in TB patients. METHODS: A retrospective medical record review was conducted of 32 TB patients who required PEG from March 1996 to April 2004. Indications and contributing factors for PEG placement were analysed. RESULTS: PEG placement was based on three different indications. In 18 patients, PEG was used to administer tube feeding, in 4 patients anti-tuberculosis drugs were administered and in 10 patients both tube feeding and antituberculosis drugs were administered. Contributing factors for PEG placement were swallowing disabilities, weakness, anti-tuberculosis drugs and their side effects, pain of neuralgic origin, hiccups and refusal of food and drugs. CONCLUSIONS: In TB, imminent and overt malnutrition, as well as the administration of drugs with a curative aim, are new indications for PEG placement. The use of PEG can overcome various problems in TB treatment and prevent treatment default.

Health system frailties in tuberculosis service provision in Russia: an analysis through the lens of formal nutritional support.

OBJECTIVE: The aim of this study was to describe health system challenges faced by tuberculosis (TB) treatment facilities in Russia through an analysis of formal institutional dietary provisions to patients in an inpatient facility that provides care for poor patients. METHODS: Analysis of formal dietary provisions by institutions and financing data from TB hospitals in Samara Oblast, Russia. RESULTS: Formal dietary provision for inpatients with TB has fallen substantially in recent years. In a hospital providing inpatient care for the poorest patients with fewest social support networks, this has been very pronounced. The likely reason for this is that financial support for other budget lines, principally salaries, has required protection. CONCLUSION: Formal institutional nutritional support in institutions providing care for the poorest patients with TB is unlikely to be enhancing the speed of recovery, or reducing the duration of infectiousness. Furthermore, the role that hospital may have played in the past in enabling patients to regain weight lost before admission may have been limited by reductions in formal financing. Reductions in state provision of food for patients may serve as an important illustration of wider TB control system frailties in the Russian Federation.

Purification and characterization of Mycobacterium tuberculosis KatG, KatG(S315T), and Mycobacterium bovis KatG(R463L).

Isoniazid, a first-line antibiotic used for the treatment of tuberculosis, is a prodrug that requires activation by the Mycobacterium tuberculosis enzyme KatG. The KatG(S315T) mutation causes isoniazid resistance while the KatG(R463L) variation is thought to be a polymorphism. Much of the work to date focused on isoniazid activation by KatG has utilized recombinant enzyme overexpressed in Escherichia coli. In this work, native KatG and KatG(S315T) were purified from M. tuberculosis, and KatG(R463L) was purified from Mycobacterium bovis. The native molecular weight, enzymatic activity, optical, resonance Raman, and EPR spectra, K(D) for isoniazid binding, and isoniazid oxidation rates were measured and compared for each native enzyme. Further, the properties of the native enzymes were compared and contrasted with those reported for recombinant KatG, KatG(S315T), and KatG(R463L) in order to assess the ability of the recombinant enzymes to act as good models for the native enzymes.

Dietary phytate reduction improves zinc absorption in Malawian children recovering from tuberculosis but not in well children.

High dietary phytate content that compromises zinc nutriture is thought to be a major problem among children of the developing world. Zinc stable isotope techniques permit the quantitative assessment of the effect of phytate reduction on zinc homeostasis. We tested the hypothesis that zinc absorption would be increased in Malawian children fed a reduced-phytate corn-plus-soy diet compared with a standard high phytate diet. Twenty-three children hospitalized in Blantyre, Malawi, were enrolled. Children were selected from those recovering from tuberculosis and from well children (those with minor injuries, those awaiting elective surgery or healthy siblings). Children received a diet of corn-plus-soy porridge (either low phytate or high phytate) for a period of 3-7 d and then participated in a zinc stable isotope study. The study included the administration of oral and intravenous zinc stable isotopes and 7-d collections of urine and stool. The diet was maintained throughout the duration of specimen collection. Zinc isotopic enrichments in urine and stool were measured, and zinc fractional absorption, total zinc absorption, endogenous fecal zinc, net zinc retention and size of the exchangeable zinc pool were calculated. Among the 14 children recovering from tuberculosis, dietary phytate reduction resulted in higher fractional absorption (0.41 +/- 0.14 versus 0.24 +/- 0.09, mean +/- SD, P: < 0.05) and total zinc absorption (169 +/- 55 versus 100 +/- 46 microg/(kg. d), P: < 0.05). No effect of phytate reduction was seen in the well children (n = 9). Phytate reduction did not decrease the absolute endogenous fecal zinc, but it did decrease it relative to total absorbed zinc. These preliminary results indicate that phytate reduction may be beneficial in improving zinc nutriture in groups with increased zinc requirements who consume a cereal-based diet.