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1.
Connecting iron regulation and mitochondrial function in Cryptococcus neoformans.
Horianopoulos, LC, Kronstad, JW
Current opinion in microbiology. 2019;:7-13
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Abstract
Iron acquisition is essential for the proliferation of microorganisms, and human pathogens such as the fungus Cryptococcus neoformans must use sophisticated uptake mechanisms to overcome host iron sequestration. Iron is of particular interest for C. neoformans because its availability is an important cue for the elaboration of virulence factors. In fungi, extracellular iron is taken up through high affinity, low affinity, siderophore-mediated, and heme uptake pathways, and the details of these mechanisms are under active investigation in C. neoformans. Following uptake, iron is transported to intracellular organelles including mitochondria where it is used in heme biosynthesis and the synthesis of iron-sulfur (Fe-S) cluster precursors. One Fe-S cluster binding protein of note is the monothiol glutaredoxin Grx4 which has emerged as a master regulator of iron sensing in C. neoformans and other fungi through its influence on the expression of proteins for iron uptake or use. The activity of Grx4 likely occurs through interactions with Fe-S clusters and transcription factors known to control expression of the iron-related functions. Although the extent to which Grx4 controls the iron regulatory network is still being investigated in C. neoformans, it is remarkable that it also influences the expression of many genes encoding mitochondrial functions. Coupled with recent studies linking mitochondrial morphology and electron transport to virulence factor elaboration, there is an emerging appreciation of mitochondria as central players in cryptococcal disease.
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2.
Exposure to Trace Elements and Risk of Skin Cancer: A Systematic Review of Epidemiologic Studies.
Matthews, NH, Fitch, K, Li, WQ, Morris, JS, Christiani, DC, Qureshi, AA, Cho, E
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2019;(1):3-21
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Abstract
Exposure to environmental trace elements has been studied in relation to many cancers. However, an association between exposure to trace elements and skin cancer remains less understood. Therefore, we conducted a systematic review of published epidemiologic literature examining the association between exposure to trace elements, and risk of melanoma and keratinocyte carcinoma in humans. We identified epidemiologic studies investigating exposure to arsenic, cadmium, chromium, copper, iron, selenium, and zinc and risk of skin cancer in humans. Among the minerals, arsenic, selenium, and zinc had more than five studies available. Exposure to arsenic was associated with increased risk of keratinocyte carcinoma, while too few studies existed on melanoma to draw conclusions. Exposure to selenium was associated with possible increased risk of keratinocyte carcinoma. Studies of zinc and skin cancer were case-control in design and were found to have inconsistent associations. The data on the association between cadmium, chromium, copper, and iron and risk of skin cancer remain too sparse to draw any conclusions. In summary, epidemiologic studies on exposure to trace elements and cutaneous malignancies are limited. Studies with larger sample sizes and prospective designs are warranted to improve our knowledge of trace elements and skin cancer.
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3.
Electrolyte minerals intake and cardiovascular health.
Mohammadifard, N, Gotay, C, Humphries, KH, Ignaszewski, A, Esmaillzadeh, A, Sarrafzadegan, N
Critical reviews in food science and nutrition. 2019;(15):2375-2385
Abstract
Appropriate intake of micronutrient, such as electrolyte minerals is critical for the well-being of the cardiovascular health system. However, there are some debates regarding the impacts of dietary and/or supplemental intake of these minerals, on the risk of cardiovascular events and associated risk factors. High sodium intake is adversely associated with the risk of hypertension. Although many reports refered to the positive association of Na intake and cardiovascular events and all-cause mortality, however, other studies indicated that low Na intake is related to higher risk of all-cause mortality and HF-related events. By contrast, dietary potassium, magnesium and calcium have an inverse correlation with cardiovascular events and risk factors, especially with blood pressure. There are some controversies about cardiovascular effects and all-cause mortality of high Ca intake, including no effect, preventive or adverse effect with or without vitamin D. Calcium supplementation might be beneficial for prevention of cardiovascular events and all-cause mortality only in individuals with low intake. Moreover, calcium intake showed a J- or U-shaped association with the risk of cardiovascular diseases. Due to the controversies of the effect of electrolyte minerals especially sodium and calcium intake on cardiovascular events, large scale, well-designed long-term randomized clinical trials are required to evaluate the effect of minerals intake on cardiovascular events and all-cause mortality. In this review, we discuss the role of dietary and or supplemental sodium, potassium, magnesium, calcium, in cardiovascular health, as well as their clinical applications, benefits, and risks for the primary prevention of cardiovascular disease, in general population.
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Role of iron in cancer development by viruses.
Shoja, Z, Chenari, M, Jafarpour, A, Jalilvand, S
Reviews in medical virology. 2019;(4):e2045
Abstract
Increased levels of iron in body are attributed to higher cancer risk. Given the fact that 16% of all human cancers are caused by viral infections, iron is suggested to play an important role in carcinogenesis particularly those induced by viral infections. The present study provides an updated summary of the literature and the plausible mechanisms of iron involvement in cancer development by viruses. Our understanding about the interplay between viral infections and iron in different settings particularly cancer development is yet to be improved as it may shed a new light in development of new therapeutic strategies.
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5.
Copper Deficiency: Causes, Manifestations, and Treatment.
Altarelli, M, Ben-Hamouda, N, Schneider, A, Berger, MM
Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition. 2019;(4):504-513
Abstract
BACKGROUND The metabolism of the essential trace element copper remains incompletely understood and, until recently, nearly ignored in acute medicine. Menkes disease was for long the only known copper deficiency condition, but several case reports and investigations conducted over the last 2 decades have shown that deficiency is more frequent than previously suspected, with devastating individual consequences and potential public health consequences. The copper needs in healthy individuals are 0.9 mg/d, which translates to 0.3 mg/d intravenously in parenteral nutrition; the present review aims at gathering actual knowledge. METHOD AND RESULTS A review of literature was conducted in PubMed and Cochrane systematic reviews to identify the most recent information about copper deficiency and generate a narrative review. Copper deficiency has hereditary and acquired origins, the latter being the most frequent. Clinical manifestations are nonspecific but affect all organs and systems, particularly the hematologic (anemia) and the neurologic (myeloneuropathy) systems. Deficiency also affects the cardiovascular, cutaneous, and immune systems. Severe copper deficiency due to reduced absorption after bariatric bypass surgery has become frequent. CONCLUSION Deficiency is more frequent than previously recognized, probably because of changing nutrition patterns but also because of some treatments that have become very common such as bypass bariatric surgery and, in acute medicine, prolonged continuous renal replacement therapy. The patients may present with severe hematologic and neurologic complications that go untreated because copper deficiency was not considered in the differential diagnosis: These complications often need active intravenous repletion with doses 4-8 times the usual nutrition recommendations.
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Distal renal tubular acidosis and severe hypokalemia: a case report and review of the literature.
Vasquez-Rios, G, Westrich, DJ, Philip, I, Edwards, JC, Shieh, S
Journal of medical case reports. 2019;(1):103
Abstract
BACKGROUND Distal renal tubular acidosis is a relatively infrequent condition with complex pathophysiology that can present with life-threatening electrolyte abnormalities. CASE PRESENTATION We describe a case of a 57-year-old Caucasian woman with previous episodes of hypokalemia, severe muscle weakness, and fatigue. Upon further questioning, symptoms of dry eye and dry mouth became evident. Initial evaluation revealed hyperchloremic metabolic acidosis, severe hypokalemia, persistent alkaline urine, and a positive urinary anion gap, suggestive of distal renal tubular acidosis. Additional laboratory workup and renal biopsy led to the diagnosis of primary Sjögren's syndrome with associated acute tubulointerstitial nephritis. After potassium and bicarbonate supplementation, immunomodulatory therapy with hydroxychloroquine, azathioprine, and prednisone was started. Nonetheless, her renal function failed to improve and remained steady with an estimated glomerular filtration rate of 42 ml/min/1.73 m2. The literature on this topic was reviewed. CONCLUSIONS Cases of renal tubular acidosis should be carefully evaluated to prevent adverse complications, uncover a potentially treatable condition, and prevent the progression to chronic kidney disease. Repeated episodes of unexplained hypokalemia could be an important clue for diagnosis.
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A Review of the Effect of Trace Metals on Freshwater Cyanobacterial Growth and Toxin Production.
Facey, JA, Apte, SC, Mitrovic, SM
Toxins. 2019;(11)
Abstract
Cyanobacterial blooms are becoming more common in freshwater systems, causing ecological degradation and human health risks through exposure to cyanotoxins. The role of phosphorus and nitrogen in cyanobacterial bloom formation is well documented and these are regularly the focus of management plans. There is also strong evidence that trace metals are required for a wide range of cellular processes, however their importance as a limiting factor of cyanobacterial growth in ecological systems is unclear. Furthermore, some studies have suggested a direct link between cyanotoxin production and some trace metals. This review synthesises current knowledge on the following: (1) the biochemical role of trace metals (particularly iron, cobalt, copper, manganese, molybdenum and zinc), (2) the growth limitation of cyanobacteria by trace metals, (3) the trace metal regulation of the phytoplankton community structure and (4) the role of trace metals in cyanotoxin production. Iron dominated the literature and regularly influenced bloom formation, with 15 of 18 studies indicating limitation or colimitation of cyanobacterial growth. A range of other trace metals were found to have a demonstrated capacity to limit cyanobacterial growth, and these metals require further study. The effect of trace metals on cyanotoxin production is equivocal and highly variable. Better understanding the role of trace metals in cyanobacterial growth and bloom formation is an essential component of freshwater management and a direction for future research.
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Coordinated regulation of nitrogen fixation and molybdate transport by molybdenum.
Demtröder, L, Narberhaus, F, Masepohl, B
Molecular microbiology. 2019;(1):17-30
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Abstract
Biological nitrogen fixation, the reduction of chemically inert dinitrogen to bioavailable ammonia, is a central process in the global nitrogen cycle highly relevant for life on earth. N2 reduction to NH3 is catalyzed by nitrogenases exclusively synthesized by diazotrophic prokaryotes. All diazotrophs have a molybdenum nitrogenase containing the unique iron-molybdenum cofactor FeMoco. In addition, some diazotrophs encode one or two alternative Mo-free nitrogenases that are less efficient at reducing N2 than Mo-nitrogenase. To permit biogenesis of Mo-nitrogenase and other molybdoenzymes when Mo is scarce, bacteria synthesize the high-affinity molybdate transporter ModABC. Generally, Mo supports expression of Mo-nitrogenase genes, while it represses production of Mo-free nitrogenases and ModABC. Since all three nitrogenases and ModABC can reach very high levels at suitable Mo concentrations, tight Mo-mediated control saves considerable resources and energy. This review outlines the similarities and differences in Mo-responsive regulation of nitrogen fixation and molybdate transport in diverse diazotrophs.
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Selenium Status in Elderly People: Longevity and Age-Related Diseases.
Robberecht, H, De Bruyne, T, Davioud-Charvet, E, Mackrill, J, Hermans, N
Current pharmaceutical design. 2019;(15):1694-1706
Abstract
BACKGROUND Selenium (Se) is a trace element active in selenoproteins, which can regulate oxidative stress. It is generally perceived as an import factor for maintaining health in the elderly. METHODS The goal of this review is to discuss selenium concentration in biological samples, primarily serum or plasma, as a function of age and its relation with longevity. The elemental level in various age-related diseases is reviewed. CONCLUSION Highest selenium values were observed in healthy adults, while in an elderly population significantly lower concentrations were reported. Variables responsible for contradictory findings are mentioned. Risk and benefits of Se-supplementation still remain under debate.
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10.
[Tracing trace elements in mental functions].
Janka, Z
Ideggyogyaszati szemle. 2019;(11-12):367-379
Abstract
Trace elements are found in the living organism in small (trace) amounts and are mainly essential for living functions. Essential trace elements are in humans the chromium (Cr), cobalt (Co), copper (Cu), fluorine (F), iodine (I), iron (Fe), manganese (Mn), molybdenum (Mo), selenium (Se), zinc (Zn), and questionably the boron (B) and vanadium (V). According to the biopsychosocial concept, mental functions have biological underpinnings, therefore the impairment of certain neurochemical processes due to shortage of trace elements may have mental consequences. Scientific investigations indicate the putative role of trace element deficiency in psychiatric disorders such in depression (Zn, Cr, Se, Fe, Co, I), premenstrual dysphoria (Cr), schizophrenia (Zn, Se), cognitive deterioration/de-mentia (B, Zn, Fe, Mn, Co, V), mental retardation (I, Mo, Cu), binge-eating (Cr), autism (Zn, Mn, Cu, Co) and attention deficit hyperactivity disorder (Fe). At the same time, the excess quantity (chronic exposure, genetic error) of certain trace elements (Cu, Mn, Co, Cr, Fe, V) can also lead to mental disturbances (depression, anxiety, psychosis, cognitive dysfunction, insomnia). Lithium (Li), being efficacious in the treatment of bipolar mood disorder, is not declared officially as a trace element. Due to nutrition (drinking water, food) the serum Li level is about a thousand times less than that used in therapy. However, Li level in the red cells is lower as the membrane sodium-Li countertransport results in a Li efflux. Nevertheless, the possibility that Li is a trace element has emerged as studies indicate its potential efficacy in such a low concentration, since certain geographic regions show an inverse correlation between the Li level of drinking water and the suicide rate in that area.