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1.
Wicherhamomyces anomalus biofilm supported on wood husk for chromium wastewater treatment.
Asri, M, El Ghachtouli, N, Elabed, S, Ibnsouda Koraichi, S, Elabed, A, Silva, B, Tavares, T
Journal of hazardous materials. 2018;:554-562
Abstract
A Wickeramomyces anomalus biofilm supported on wood husk was used to remediate water bodies contaminated with chromium (Cr), in batch and open systems. The favorable adhesion ability of the chromium-resistant yeast strain on the wood husk was predicted by XDLVO theory and confirmed by environmental scanning electronic microscopy. The chromium decontamination was then optimized in a batch mode using a central composite design (CCD). Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of 0.93-0.91 for Cr(VI) and total Cr removal, respectively, ensuring a satisfactory fitting of the second-order regression model to the experimental data. In batch system, the concentration of biomass exhibited the minimal effect on the process. An acidic pH of 3.72 and 5.48, an initial chromium concentration of 10 and 16.91 mg/L and a support dose of 6.95 and 8.20 g/L were optimal for Cr(VI) and total Cr removal, respectively. The breakthrough curves were determined in open system for different initial chromium concentrations. The study of glucose concentration effect on the yeast extracellular polymeric substances (EPS) production showed that a medium exempt of glucose allowed maximal EPS production and minimal chromium removal efficiency, while 20 g/L glucose concentration of presented the optimal condition for chromium removal.
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2.
Investigation of Cr(VI) reduction potential and mechanism by Caldicellulosiruptor saccharolyticus under glucose fermentation condition.
Bai, YN, Lu, YZ, Shen, N, Lau, TC, Zeng, RJ
Journal of hazardous materials. 2018;:585-592
Abstract
This study examined the microbial reduction of hexavalent chromium [Cr(VI)] by an extremely thermophilic bacterium, Caldicellulosiruptor saccharolyticus, under glucose fermentation conditions at 70°C. Experimentation with different initial Cr(VI) concentrations confirmed that C. saccharolyticus had the ability to reduce Cr(VI) and immobilize Cr(III). At a concentration of 40mg/L, Cr(VI) was completely reduced within 12h, and 97% of the reduction product Cr(III) precipitated on the cell surface. Cr(VI) reduction was accelerated by the addition of neutral red (NR, an electron mediator), resulting in the reduction time shortened to 1h. The addition of CuCl2, a Ni-Fe hydrogenase inhibitor, also enhanced Cr(VI) reduction. Additionally, analysis of the relationship between Cr(VI) reduction and glucose fermentation suggested that different electron sources acted during CuCl2 and NR conditions. Hydrogen served as an electron donor under normal fermentation and NR conditions with the catalysis of Ni-Fe hydrogenase. However, when the activity of Ni-Fe hydrogenase was inhibited by CuCl2, C. saccharolyticus directly used reduction equivalents during glucose fermentation for intracellular Cr(VI) reduction. Therefore, our findings demonstrated high Cr(VI) reduction ability and different electron transfer pathways during Cr(VI) reduction by C. saccharolyticus.
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3.
Evaluation of Cobalt and Chromium Levels Following Implantation of Cobalt Chromium Coronary Stents: A Pilot Study.
Di Santo, P, Motazedian, P, Jung, RG, Simard, T, Ramirez, FD, Chong, AY, Glover, C, Hibbert, B, Dwivedi, G
Heart, lung & circulation. 2018;(6):763-766
Abstract
BACKGROUND Large increases in myocardial trace elements may adversely affect metabolism and become detrimental to cardiac function. Percutaneous coronary intervention (PCI) allows for the revascularisation of obstructive coronary artery disease using drug-eluting stents. These stents are comprised of a metallic stent backbone covered in an engineered polymer which delivers a drug over a prescribed period to the vessel wall. Given the potential implications of trace metal accumulation within the myocardium, our goal is to determine if metallic coronary stents are able to cause detectable elevations in serum cobalt and/or chromium levels. METHODS This study was a single centre, observational, pilot study with 20 patients who underwent planned PCI with implantation of a cobalt chromium drug eluting stent. Serum blood samples were drawn at baseline prior to PCI, 4hours post-stent deployment and at the time of routine follow-up after PCI. All blood samples were analysed for cobalt and chromium concentrations. The primary outcome of this study was the difference in serum cobalt and chromium levels at routine clinical follow-up. RESULTS The mean follow up was 64.1±17.3 days. There was no difference in serum cobalt levels when comparing baseline and routine clinical follow up (3.32±2.14nmol/L vs. 3.14±1.00nmol/L, p=0.99) nor in chromium levels (4.24±2.31nmol/L vs. 2.82±1.22 nmol/L, p=0.11). There was also no difference between baseline and 4hours post-PCI serum concentrations. CONCLUSIONS Percutaneous coronary intervention with cobalt chromium coronary stents does not appear to cause an elevation in these trace element serum concentrations.
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4.
Determining the cross-talk between smooth muscle cells and macrophages on a cobalt-chromium stent material surface using an in vitro postimplantation coculture model.
Anderson, JA, Lamichhane, S, Vierhout, T, Engebretson, D
Journal of biomedical materials research. Part A. 2018;(3):673-685
Abstract
Smooth muscle cells (SMCs) and macrophages are important cellular components involved in the development of complications following the implantation of cardiovascular devices. This leads to various disorders such as restenosis, chronic inflammation, and may ultimately result in device failure. In this study, we developed a postimplant stent coculture model using different ratios of SMCs and macrophages seeded on to cobalt-chromium alloy. The macrophages had an increased affinity to the coculture surfaces, which resulted in decreased SMC attachment to the alloy surfaces at the initial time point. Once adhered, the macrophages spread freely and displayed advanced stages of inflammation at 48 h when cocultured with SMCs. This resulted in an increased secretion of proinflammatory cytokines (tumor necrosis factor alpha, monocyte chemotactic protein 1, interleukin [IL]-6, and IL-8) by 48 h in the coculture samples with the greatest increase observed with the high number of macrophages. Therefore, the increased levels of proinflammatory cytokines promoted the growth of SMCs in coculture to a greater extent than when the SMCs were culture alone. Thus, this study demonstrated the constant cross-talk between SMCs and macrophages occurring on the postimplant stent surface. Similar coculture models can be used to test the biocompatibility of drugs and biomaterials at possible postimplantation scenarios. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 673-685, 2018.
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5.
Chromium supplementation does not improve weight loss or metabolic and hormonal variables in patients with polycystic ovary syndrome: A systematic review.
Maleki, V, Izadi, A, Farsad-Naeimi, A, Alizadeh, M
Nutrition research (New York, N.Y.). 2018;:1-10
Abstract
Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age, and recently, chromium was discussed as an adjuvant way to manage it. Herein, a systematic review was conducted which centered on the effects of chromium on ovarian physiology with a focus on body mass index, as well as hormonal and metabolic dysfunctions in women suffering from PCOS. This review was performed using the guidelines from Preferred Reporting Items for Systematic Reviews. Clinical trials investigating chromium in women with PCOS with outcome measures related to metabolic and hormonal status were included. The search was conducted using PubMed, Scopus, and Google Scholar databases for clinical trials in the English language from the inception of the resources until May 2017 with the terms: chromium, chromium picolinate, CrP, polycystic ovary syndrome, PCOS, and sclerocystic ovary syndrome. The search resulted in 89 articles, and after inclusion and exclusion criteria were applied, 6 articles were selected for analysis. Two studies that evaluated the effect of chromium on body weight or body mass index reported no effect. Another study reported the beneficial effect of chromium on weight reduction. It seems that the effect of chromium in the reduction of blood glucose is insignificant, and results are inconsistent in relation to dyslipidemia. With regard to the effects of chromium on concentrations of sex hormones, a longer duration of treatment is needed to produce significant changes. The articles reviewed demonstrated that chromium supplementation has limited effects on weight reduction, glucose control, lipid profile, and hormonal disturbance of women with PCOS; however, more studies are needed due to the clinical changes observed in patients with PCOS after chromium supplementation.
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6.
Chromium supplementation in women with polycystic ovary syndrome: Systematic review and meta-analysis.
Tang, XL, Sun, Z, Gong, L
The journal of obstetrics and gynaecology research. 2018;(1):134-143
Abstract
AIM: Increasing evidence has suggested that chromium supplementation may improve the clinical symptoms of polycystic ovary syndrome (PCOS), yet the results have been inconsistent. To derive a more precise estimation of the efficacy of chromium, a meta-analysis was performed. METHODS Studies published in PubMed, EMBASE and the Cochrane Library up to April 2017 were retrieved. Standardized mean differences (SMD) with 95%CI were calculated for net changes using random-effects or fixed-effects models. RESULTS A total of six randomized clinical trials (RCT) with 351 PCOS women were ultimately collected in this meta-analysis. All included RCT were of moderate-high quality. On pooled analysis, insulin resistance was significantly decreased (SMD, -0.84; 95%CI: -1.30 to -0.38; P = 0.0004), while the total testosterone (SMD, 0.36; 95%CI: 0.07-0.65; P = 0.02) and free testosterone (SMD, 0.80; 95%CI: 0.48-1.12; P < 0.00001) were markedly increased in chromium-treated PCOS patients compared with control groups. No significant difference was found in other indexes of insulin metabolism (body mass index, fasting insulin, fasting blood sugar and quantitative insulin sensitivity check index), hormone status (luteinizing hormone, follicle-stimulating hormone and prolactin) and lipid profiles (cholesterol and triglycerides) between the two groups. CONCLUSION Supplementation with chromium may not have significant benefits for women with PCOS. More RCT with low heterogeneity, however, are required to corroborate the present findings.
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7.
The Effects of Supplementation with Chromium on Insulin Resistance Indices in Women with Polycystic Ovarian Syndrome: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.
Heshmati, J, Omani-Samani, R, Vesali, S, Maroufizadeh, S, Rezaeinejad, M, Razavi, M, Sepidarkish, M
Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme. 2018;(3):193-200
Abstract
Recently, the effects of nutritional supplementation on improvement or prevention of polycystic ovary syndrome (PCOS) have been considered. Several studies have been carried out on the effect of chromium supplementation in improving PCOS patients. This study aimed to summarize the available findings regarding the effect of chromium on improving the polycystic ovary syndrome. The review includes randomized controlled trials (RCTs) comparing chromium treatment with placebo or other treatments in women with PCOS. Women with PCOS diagnosed according to the ESHRE/ASRM or NIH criteria in reproductive age were eligible. Electronic searches using the MeSH terms were conducted in the following databases: Medline, Embase, Scopus, Web of Science, and The Cochrane Library. Effects were measured as weighted mean difference (WMD) and 95% confidence intervals (CI) for studies of PCOS and control subjects were calculated by using random-effects model. The initial search yielded potentially 100 relevant articles of randomized clinical trials on dietary chromium supplements: 16 from Pubmed, 36 from Embase, 29 from Scopus, and 19 from Web of Science. After studying these publications, 5 were potentially eligible and retrieved in full text. The five studies included in the meta-analysis reported data on 137 women with PCOS and 131 controls. A meta-analysis of 5 studies showed a non-significant difference in fasting insulin between chromium, and placebo or other treatment (mean difference (MD): -1.14; (95% CI: -4.11 to 1.83, p=0.45). We retrieved two randomized controlled trials, in which Quantitative Insulin Sensitivity Check Index (QUICKI) was compared between chromium, and placebo or other treatment in 156 women with PCOS. Meta-analysis of two RCTs showed no significant difference in QUICKI score between chromium and placebo (MD: 0.01; 95% CI: -0.01 to 0.04, p=0.34). Two randomized controlled trials compared Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) between chromium, and placebo or other treatment in 81 women with PCOS. After combining the data, there was a significantly lower HOMA-IR in the chromium group (MD: -1.68; 95% CI: -2.42 to -0.94, p<0.001). One RCT reported a significant difference in Homeostatic Model Assessment-beta-cell function (HOMA-B) between chromium and placebo groups (-15.5±32.3 vs. +13.6±23.1, p<0.001). No significant effect of chromium on fasting insulin and QUICKI score was found in women with PCOS. Chromium supplementation significantly improved HOMA-IR and HOMA-B among patients with diabetes. The magnitude of the effect is small, and the clinical relevance is uncertain. Future trials in well characterized studies that address the limitations in the current evidence are needed before definitive claims can be made about the effect of chromium supplementation.
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8.
PBMC fixation and processing for Chromium single-cell RNA sequencing.
Chen, J, Cheung, F, Shi, R, Zhou, H, Lu, W, ,
Journal of translational medicine. 2018;(1):198
Abstract
BACKGROUND Interest in single-cell transcriptomic analysis is growing rapidly, especially for profiling rare or heterogeneous populations of cells. In almost all reported works investigators have used live cells, which introduces cell stress during preparation and hinders complex study designs. Recent studies have indicated that cells fixed by denaturing fixative can be used in single-cell sequencing, however they did not usually work with most types of primary cells including immune cells. METHODS The methanol-fixation and new processing method was introduced to preserve human peripheral blood mononuclear cells (PBMCs) for single-cell RNA sequencing (scRNA-Seq) analysis on 10× Chromium platform. RESULTS When methanol fixation protocol was broken up into three steps: fixation, storage and rehydration, we found that PBMC RNA was degraded during rehydration with PBS, not at cell fixation and up to 3-month storage steps. Resuspension but not rehydration in 3× saline sodium citrate (SSC) buffer instead of PBS preserved PBMC RNA integrity and prevented RNA leakage. Diluted SSC buffer did not interfere with full-length cDNA synthesis. The methanol-fixed PBMCs resuspended in 3× SSC were successfully implemented into 10× Chromium standard scRNA-seq workflows with no elevated low quality cells and cell doublets. The fixation process did not alter the single-cell transcriptional profiles and gene expression levels. Major subpopulations classified by marker genes could be identified in fixed PBMCs at a similar proportion as in live PBMCs. This new fixation processing protocol also worked in several other fixed primary cell types and cell lines as in live ones. CONCLUSIONS We expect that the methanol-based cell fixation procedure presented here will allow better and more effective batching schemes for a complex single cell experimental design with primary cells or tissues.
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9.
Chromium(VI) Toxicity in Legume Plants: Modulation Effects of Rhizobial Symbiosis.
Stambulska, UY, Bayliak, MM, Lushchak, VI
BioMed research international. 2018;:8031213
Abstract
Most legume species have the ability to establish a symbiotic relationship with soil nitrogen-fixing rhizobacteria that promote plant growth and productivity. There is an increasing evidence of reactive oxygen species (ROS) important role in formation of legume-rhizobium symbiosis and nodule functioning. Environmental pollutants such as chromium compounds can cause damage to rhizobia, legumes, and their symbiosis. In plants, toxic effects of chromium(VI) compounds are associated with the increased production of ROS and oxidative stress development as well as with inhibition of pigment synthesis and modification of virtually all cellular components. These metabolic changes result in inhibition of seed germination and seedling development as well as reduction of plant biomass and crop yield. However, if plants establish symbiosis with rhizobia, heavy metals are accumulated preferentially in nodules decreasing the toxicity of metals to the host plant. This review summarizes data on toxic effects of chromium on legume plants and legume-rhizobium symbiosis. In addition, we discussed the role of oxidative stress in both chromium toxicity and formation of rhizobial symbiosis and use of nodule bacteria for minimizing toxic effects of chromium on plants.
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10.
Biosorption and biotransformation of hexavalent chromium [Cr(VI)]: A comprehensive review.
Jobby, R, Jha, P, Yadav, AK, Desai, N
Chemosphere. 2018;:255-266
Abstract
Chromium (VI) is one of the most common environmental contaminant due to its tremendous industrial applications. It is non-biodegradable as it is a heavy metal, and hence, of major concern. Therefore, it is pertinent that the remediation method should be such that brings chromium within permissible limits before the effluent is discharged. Several different strategies are adopted by microorganisms for Cr (VI) removal mostly involving biosorption and biotransformation or both. These mechanisms are based on the surface nature of the biosorbent and the availability of reductants. This review article focuses on chromium pollution problem, its chemistry, sources, effects, remediation strategies by biological agents and detailed chromium detoxification mechanism in microbial cell. A summary of applied in situ and ex situ chromium bioremediation technologies is also listed. This can be helpful for developing technologies to be more efficient for Cr (VI) removal thereby bridging the gap between laboratory findings and industrial application for chromium remediation.