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Metal homeostasis in infectious disease: recent advances in bacterial metallophores and the human metal-withholding response.
Neumann, W, Gulati, A, Nolan, EM
Current opinion in chemical biology. 2017;:10-18
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Abstract
A tug-of-war between the mammalian host and bacterial pathogen for nutrients, including first-row transition metals (e.g. Mn, Fe, Zn), occurs during infection. Here we present recent advances about three metal-chelating metabolites that bacterial pathogens deploy when invading the host: staphylopine, staphyloferrin B, and enterobactin. These highlights provide new insights into the mechanisms of bacterial metal acquisition and regulation, as well as the contributions of host-defense proteins during the human innate immune response. The studies also underscore that the chemical composition of the microenvironment at an infection site can influence bacterial pathogenesis and the innate immune system.
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[Effect of zinc amino acid chelate and zinc sulfate in the incidence of respiratory infection and diarrhea among preschool children in child daycare centers].
Sánchez, J, Villada, OA, Rojas, ML, Montoya, L, Díaz, A, Vargas, C, Chica, J, Herrera, AA
Biomedica : revista del Instituto Nacional de Salud. 2014;(1):79-91
Abstract
INTRODUCTION Zinc deficiency is common in children among populations in developing areas. Zinc deficiency alters the immune system and the resistance to infections. OBJECTIVE To evaluate the effect of two zinc compounds in the prevention of acute respiratory infection and acute diarrhea. MATERIALS AND METHODS Randomized triple-blind community trial with 301 children between 2-5 years of age from six child daycare centers in Medellin, Colombia. Children were distributed in three groups receiving zinc amino acid chelate, zinc sulfate and placebo five days a week for 16 weeks. Daily symptoms of respiratory infection, acute diarrhea and side effects were evaluated. RESULTS The incidence of respiratory infection was lower with zinc amino acid chelate (1.42 per 1,000 child-days) compared with placebo (3.3 per 1,000 child-days) (RR=0.43, 95% CI: 0.196 to 0.950, p=0.049) and with zinc sulfate (1.57 per 1,000 child-days) (RR=0.90, 95% CI 0.382 to 2.153, p=0.999). The incidence of acute diarrhea with zinc amino acid chelate (0.15 per 1,000 child-days) was lower than with placebo (0.49 per 1,000 child-days) (RR=0.32, 95% CI 0.006 to 3.990, p=0.346) and with zinc sulfate (0.78 per 1,000 child-days) (RR=0.20, 95% CI: 0.0043 to 1.662, p=0.361). CONCLUSIONS Zinc amino acid chelate had a better effect in reducing the incidence of acute respiratory infection and acute diarrhea in preschool children when compared with the other groups.
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Cytotoxic effects of intra and extracellular zinc chelation on human breast cancer cells.
Hashemi, M, Ghavami, S, Eshraghi, M, Booy, EP, Los, M
European journal of pharmacology. 2007;(1):9-19
Abstract
Zinc is an essential trace element with cofactor functions in a large number of proteins of intermediary metabolism, hormone secretion pathways, immune defence mechanisms, and as a cofactor of transcription factors it is also involved in the control of gene expression. Our study demonstrates that the modulation of intra and extracellular zinc alone is sufficient to induce metabolic changes or even apoptosis in two model human breast cancer cell lines MCF-7 and MDA-MB468. Treatment of breast cancer cells with different concentrations of a cell membrane permeable zinc chelator, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and the membrane impermeable zinc chelator, diethylenetriaminepentacetic acid, (DTPA) resulted in a significant increase of cell death. Features of apoptosis, such as chromatin condensation and nuclear fragmentation accompanied the DTPA and TPEN-induced cell death. A significant increase in the activity of caspase-9 was observed in both cell lines; whereas, caspase-3 activity was only increased in MDA-MB468 cells since caspase-3 is not expressed in MCF-7 cells. Caspase-8 activation was negligible in both cell lines. Addition of Zn(2+) or Cu(2+) prevented DTPA and TPEN-induced cytotoxicity, indicating that both bivalent cations can be replaced functionally to a certain extent in our experimental system. Interestingly, addition of Ca(2+), or Mg(2+) had no effect. The antioxidant N-Acetyl-L-Cysteine inhibited the cytotoxic effect of DTPA and TPEN, indicating that oxidative stress is the likely mediator of Zn-deficiency-related cell death.
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Systematic review and meta-analysis: D-Penicillamine vs. placebo/no intervention in patients with primary biliary cirrhosis--Cochrane Hepato-Biliary Group.
Gong, Y, Klingenberg, SL, Gluud, C
Alimentary pharmacology & therapeutics. 2006;(11-12):1535-44
Abstract
BACKGROUND D-Penicillamine is used for patients with primary biliary cirrhosis due to its ability to decrease hepatic copper and modulate the immune response. The results on effects of D--penicillamine in randomized-clinical trials of primary biliary cirrhosis patients are inconsistent. AIM: To systematically evaluate the benefits and harms of D-penicillamine for patients with primary biliary cirrhosis. METHODS We have performed a systematic review with meta-analyses of randomized-clinical trials to evaluate the effects of D-penicillamine for primary biliary cirrhosis. The primary outcomes are mortality and mortality or liver transplantation. We analysed the data by fixed-effect and random-effect models. RESULTS Seven randomized trials including 706 patients were analysed. d-Penicillamine was without significant effects on mortality (RR 1.08, 95% CI: 0.82-1.43, P = 0.56), mortality or liver transplantation (RR 1.11, 95% CI: 0.74-1.68, P = 0.62), pruritus, liver complications, progression of liver histological stage and liver biochemical variables. D--Penicillamine significantly decreased serum alanine aminotransferase activity (weighted mean difference -45 IU/L, 95% CI: -75 to -15, P < 0.05) and led to significantly more adverse events (RR 4.18, 95% CI: 1.38-12.69, P = 0.01). CONCLUSION D-Penicillamine did not appear to reduce the risk of mortality or morbidity, and led to more adverse events in patients with primary biliary cirrhosis.
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Iron overload and tuberculosis: a case for iron chelation therapy.
Cronje, L, Bornman, L
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease. 2005;(1):2-9
Abstract
Elevated levels of iron impair immune defence mechanisms, and specifically the macrophage function of innate immunity. Iron enhances Mycobacterium tuberculosis infection, M. tuberculosis replication, progression to clinical disease and death from tuberculosis (TB). Chelation of iron in individuals with an excessive iron burden may reduce M. tuberculosis viability and replication, restore host defence mechanisms and could find application in the prevention and treatment strategies in settings where both iron overload and TB are prevalent. The objective of this paper was to summarise recent literature on the role of iron in TB pathogenesis and to examine the potential of iron chelation therapy. The literature confirms a key role for iron in mycobacterial virulence. The ability of chelation to enhance host effector mechanisms and to inhibit replication of various pathogens justifies further studies into iron chelation as a potential additive therapy for TB.
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Mercury exposure: evaluation and intervention the inappropriate use of chelating agents in the diagnosis and treatment of putative mercury poisoning.
Risher, JF, Amler, SN
Neurotoxicology. 2005;(4):691-9
Abstract
Public awareness of the potential for mercury to cause health problems has increased dramatically in the last 15 years. It is now widely recognized that significant exposure to all forms of mercury (elemental/metallic and both inorganic and organic compounds) can result in a variety of adverse health effects, including neurological, renal, respiratory, immune, dermatologic, reproductive, and developmental sequellae. And while the various media have made the general population cognizant of the need to avoid unnecessary exposure to this naturally occurring element, there has also evolved a growing tendency to attribute unexplainable neurologic, as well as other, signs and symptoms to mercury, whether or not significant exposure to mercury has actually occurred. For the physician, making a diagnosis of mercury intoxication can be difficult, because many of the clinical signs and symptoms of mercury exposure can also be attributed to any number of causes, including undiagnosed neurological diseases, pharmacotherapy, vitamin or mineral deficiencies, and psychological stress. The physician must be able to recognize the clinical manifestations of mercury intoxication, and understand the importance of biological markers in making a definitive diagnosis of mercury poisoning. In a desire to treat the patient complaining of symptoms similar to some that can be caused by mercury, a growing number of physicians, particularly those in alternative medicine fields, result to chelation to "rid" the body of the mercury, believed to be the cause of the ailments. And although the use of chelation is increasing, controlled studies showing that this procedure actually improves outcome are lacking. If chelation therapy is considered to be indicated, the attending physician should communicate the risks of chelation to the patient before beginning treatment with metal-chelating drugs.