Chromium exposure and incidence of metabolic syndrome among American young adults over a 23-year follow-up: the CARDIA Trace Element Study

Efficacy and Tolerability of a Food Supplement Based on Zea mays L., Gymnema sylvestre (Retz.) R.br.ex Sm, Zinc and Chromium for the Maintenance of Normal Carbohydrate Metabolism: A Monocentric, Randomized, Double-Blind, Placebo-Controlled Clinical Trial

A study on 81 individuals (18-75 years old) with mildly impaired fasting blood glucose (FBG) concentrations (98-125 mg/dL) was undertaken to investigate the tolerability of a food supplement (FS) based on Zea mays and Gymnema sylvestre extracts, zinc, and chromium and its efficacy on glucose and lipid metabolism. The subjects were randomized into three groups (27 in each group) and supplemented with one or two tablet(s)/day of FS (groups 1 and 2, respectively), or two tablets/day of placebo (group 3). Blood sampling was carried out at baseline (t0) and after a 3-month treatment (t1), and biochemical parameters associated with glucose and lipid metabolism and kidney and liver toxicity were evaluated. Compared to the placebo, FBG and glycated haemoglobin (HbA1c) were significantly (p < 0.001) reduced in group 1 subjects. In contrast, at the doses of one and two tablet(s)/day, the FS exerted no effect on the other parameters examined. We conclude that in subjects with slightly impaired FBG, ingestion of a FS based on Z. mays and G. sylvestre extracts, zinc, and chromium over 3 months lowers FBG and modulates glucose homeostasis by improving glucose metabolism. These beneficial effects occur in the absence of biochemical evidence of kidney and liver toxicity.

Contaminant Metals and Cardiovascular Health

A growing body of research has begun to link exposure to environmental contaminants, such as heavy metals, with a variety of negative health outcomes. In this paper, we sought to review the current research describing the impact of certain common contaminant metals on cardiovascular (CV) health. We reviewed ten metals: lead, barium, nickel, chromium, cadmium, arsenic, mercury, selenium, zinc, and copper. After a literature review, we briefly summarized the routes of environmental exposure, pathophysiological mechanisms, CV health impacts, and exposure prevention and/or mitigation strategies for each metal. The resulting article discloses a broad spectrum of pathological significance, from relatively benign substances with little to no described effects on CV health, such as chromium and selenium, to substances with a wide-ranging and relatively severe spectrum of CV pathologies, such as arsenic, cadmium, and lead. It is our hope that this article will provide clinicians with a practical overview of the impact of these common environmental contaminants on CV health as well as highlight areas that require further investigation to better understand how these metals impact the incidence and progression of CV diseases.

Regulation of enzymatic and non-enzymatic antioxidants in rice seedlings against chromium stress through sodium hydrosulfide and sodium nitroprusside

Hydrogen sulfide (H₂S) and nitric oxide (NO) play a well-organized protective mechanism in coping with oxidative stress induced by toxic metals. However, the comparative effects of H₂S and NO on enzymatic and non-enzymatic antioxidants in plants under Cr(III) stress have not been defined. In this study, we mathematically evaluate the importance of sodium hydrosulfide (NaHS) and sodium nitroprusside (SNP) on these two antioxidant systems in rice seedlings under Cr(III) stress. The results displayed that the optimal dose of NaHS and SNP was 100 μM and 75 μM, respectively, in rice tissues under Cr(III) stress, judging by the reactive oxygen species (ROS) levels in rice tissues. When rice seedlings were exposed to Cr(III) at concentrations of 3.57, 7.24, 26.52 mg Cr/l, Cr-induced ROS accumulation had a significant (p < 0.05) effect on the lipid peroxidation of cell membrane in rice tissues, and decreased the response of SOD, CAT, Pro, GSH, and AsA in rice tissues. Application of exogenous NaHS and SNP effectively (p < 0.05) alleviated the toxic effects of Cr(III) in rice seedlings by activating different antioxidants. A novel physiological response model suggested that the regulatory effect of NaHS and SNP on non-enzymatic antioxidants was stronger than that of enzymatic antioxidants. Moreover, NaHS-mediated response intensity of both enzymatic and non-enzymatic antioxidants was greater than that of SNP, suggesting the importance of utilizing NaHS over SNP as antioxidant regulators during detoxification of Cr(III) in rice seedlings.

Independent, combine and interactive effects of heavy metal exposure on dyslipidemia biomarkers: A cross-sectional study in northeastern China

Dyslipidemia is a common disease in the older population and represents a considerable disease burden worldwide. Epidemiological and experimental studies have indicated associations between heavy metal exposure and dyslipidemia; few studies have investigated the effects of heavy metal mixture and interactions between metals on dyslipidemia. We recruited 1121 participants living in heavy metal-contaminated and control areas in northeast China from a cross-sectional survey (2017-2019). Urinary metals including chromium (Cr), cadmium (Cd), lead (Pb), and manganese (Mn) and dyslipidemia biomarkers, namely triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels, were measured. The generalized linear model (GLM) was used to explore the association of a single metal with dyslipidemia biomarkers. Bayesian kernel machine regression (BKMR) and multivariable linear regression were performed to explore the overall effect of metal mixture and the interaction between metals on dyslipidemia. Heavy metal mixture was positively associated with LDL-C, TC, and TG and negatively with HDL-C. In multivariable linear regression, Pb and Cd exhibited a synergistic association with LDL-C in the participants without hyperlipemia. Mn-Cd and Pb-Cr also showed a synergistic association with increasing the level of LDL-C in subjects without hyperlipemia. Cd-Cr showed an antagonistic association with HDL-C, respectively. Cr-Mn exhibited an antagonistic association with decreased HDL-C and TG levels. No significant interaction was noted among the three metals. Our study indicated that exposure to heavy metals is associated with dyslipidemia biomarkers and the presence of potential synergistic or antagonistic interactions between the heavy metals.

A low chromium diet increases body fat, energy intake and circulating triglycerides and insulin in male and female rats fed a moderately high-fat, high-sucrose diet from peripuberty to young adult age

Trivalent chromium (Cr) may function to potentiate the action of insulin, but the effects of chromium intakes on metabolic parameters are unclear. Cr is listed as a potentially beneficial element for rodents based on studies that show feeding low quantities affect glucose metabolism. Cr is recommended at 1 mg per kg in rodent diets. This study examined the effects of different levels of dietary Cr on body weight, body composition, energy intake, food efficiency and metabolic parameters of lipid and glucose metabolism in male and female rats when fed from peripuberty to young adult age in the background of a moderately high-fat, high-sucrose diet. Sprague-Dawley CD rats (n = 10 males and 10 females/group) at 35 days of age were assigned by weight to the low (LCr, 0.33 ± 0.06 mg/kg), normal (NCr, 1.20 ± 0.11 mg/kg) or high (HCr, 9.15 ± 0.65 mg/kg) Cr diets. Diets were fed ad libitum for 12 weeks (83 days). At baseline, body weights and composition were similar (p≥0.05) among diet groups. Compared to the NCr group, the LCr group weighed more (p<0.01) and consumed more energy (food) from Day 56 onwards, but food efficiency was unaffected. Following an oral glucose challenge (Day 77), dietary chromium levels did not affect plasma glucose, but fasting plasma insulin and insulin at 30 and 60 min after dosing were higher in the LCr group compared to the NCr group. At the end of the study, whole-body fat, accrued body fat from baseline and fasting serum triglycerides were higher in the LCr group compared to the NCr group. Effects were similar in both sexes and not observed in the HCr group. These data show that low dietary Cr affects metabolic parameters common in chronic diseases underscoring the need for clinical trials to define the nutritional and/or pharmacological effects of Cr.

Metal mixtures with longitudinal changes in lipid profiles: findings from the manganese-exposed workers healthy cohort

The majority of epidemiological investigations on metal exposures and lipid metabolism employed cross-sectional designs and focused on individual metal. We explored the associations between metal mixture exposures and longitudinal changes in lipid profiles and potential sexual heterogeneity. We recruited 250 men and 73 women, aged 40 years at baseline (2012), and followed them up in 2020, from the manganese-exposed workers healthy cohort. We detected metal concentrations of blood cells at baseline with inductively coupled plasma mass spectrometry. Lipid profiles were repeatedly measured over 8 years of follow-up. We performed sparse partial least squares (sPLS) model to evaluate multi-pollutant associations. Bayesian kernel machine regression was utilized for metal mixtures as well as evaluating their joint impacts on lipid changes. In sPLS models, a positive association was found between manganese and change in total cholesterol (TC) (beta = 0.169), while a negative association was observed between cobalt (beta =  - 0.134) and change in low density lipoprotein cholesterol (LDL-C) (beta =  - 0.178) among overall participants, which were consistent in men. Interestingly, rubidium was positively associated with change in LDL-C (beta = 0.273) in women, while copper was negatively associated with change in TC (beta =  - 0.359) and LDL-C (beta =  - 0.267). Magnesium was negatively associated with change in TC (beta =  - 0.327). We did not observe the significantly cumulative effect of metal mixtures on lipid changes. In comparison to other metals, manganese had a more significant influence on lipid change [group PIP (0.579) and conditional PIP (0.556) for TC change in men]. Furthermore, male rats exposed to manganese (20 mg/kg) had higher levels of LDL-C in plasma and more apparent inflammatory infiltration, vacuolation of liver cells, nuclear pyknosis, and fatty change than the controls. These findings highlight the potential role of metal mixtures in lipid metabolism with sex-dependent heterogeneity. More researches are needed to explore the underlying mechanisms.

Removal of hexavalent chromium via biochar-based adsorbents: State-of-the-art, challenges, and future perspectives

Chromium originates from geogenic and extensive anthropogenic activities and significantly impacts natural ecosystems and human health. Various methods have been applied to remove hexavalent chromium (Cr(VI)) from aquatic environmental matrices, including adsorption via different adsorbents, which is considered to be the most common and low-cost approach. Biochar materials have been recognized as renewable carbon sorbents, pyrolyzed from various biomass at different temperatures under limited/no oxygen conditions for heavy metals remediation. This review summarizes the sources, chemical speciation & toxicity of Cr(VI) ions, and raw and modified biochar applications for Cr(VI) remediation from various contaminated matrices. Mechanistic understanding of Cr(VI) adsorption using different biochar-based materials through batch and saturated column adsorption experiments is documented. Electrostatic interaction and ion exchange dominate the Cr(VI) adsorption onto the biochar materials in acidic pH media. Cr(VI) ions tend to break down as HCrO₄^-, CrO₄^2-, and Cr₂O₇^2- ions in aqueous solutions. At low pH (∼1-4), the availability of HCrO₄^- ions attributes the electrostatic forces of attraction due to the available functional groups such as -NH₄⁺, -COOH, and -OH₂⁺, which encourages higher adsorption of Cr(VI). Equilibrium isotherm, kinetic, and thermodynamic models help to understand Cr(VI)-biochar interactions and their adsorption mechanism. The adsorption studies of Cr(VI) are summarized through the fixed-bed saturated column experiments and Cr-contaminated real groundwater analysis using biochar-based sorbents for practical applicability. This review highlights the significant challenges in biochar-based material applications as green, renewable, and cost-effective adsorbents for the remediation of Cr(VI). Further recommendations and future scope for the implications of advanced novel biochar materials for Cr(VI) removal and other heavy metals are elegantly discussed.

Preparation and hypoglycemic effects of chromium- and zinc-rich Acetobacter aceti

BACKGROUND

At present, there is no ideal method to cure diabetes, and there are few reports on the treatment of diabetes with probiotics.

AIM

To propose a method for preparing a new type of chromium- and zinc-rich Acetobacter aceti (A. aceti) and explore its ability to enhance the hypoglycemic effects of probiotics in the treatment of diabetes.

METHODS

A. aceti was cultured in a liquid medium that contained chromium trichloride and zinc chloride, both at a concentration of 64 mg/mL, with the initial concentration of the bacterial solution 1 × 10⁴ CFU/mL. After the bacterial solution had been inducted for 48 h, the culture media was changed and the induction was repeated once. The levels of chromium and zinc in the bacteria were detected by inductively coupled plasma mass spectrometry, and the contents of NADH and glucose dehydrogenase were determined using an NAD/NADH kit and glucose dehydrogenase kit, respectively. Streptozotocin was used to establish a mouse model to evaluate the hypoglycemic effects of the proposed chromium- and zinc-rich A. aceti. Ten-times the therapeutic dose was administered to evaluate its biological safety. The effect on MIN6 islet cells was also assessed in vitro.

RESULTS

The levels of chromium metal, metallic zinc, NADH coenzyme, and glucose dehydrogenase in A. aceti prepared by this method were 28.58-34.34 mg/kg, 5.35-7.52 mg/kg, 5.13-7.26 μM, and 446.812-567.138 U/g, respectively. The use of these bacteria resulted in a better hypoglycemic effect than metformin, promoting the repair of tissues and cells of pancreatic islets in vivo and facilitating the growth of MIN6 pancreatic islet cells and increasing insulin secretion in vitro. Ten-times the therapeutic dose of treatment was non-toxic to mice.

CONCLUSION

Chromium trichloride and zinc chloride can be employed to induce the preparation of chromium- and zinc-rich A. aceti, which can then promote the hypoglycemic effect found in normal A. aceti. The bacteria biotransforms the chromium and zinc in a way that could increase their safety as a treatment for diabetes.

Experimental and Molecular Modeling Studies on the Complexation of Chromium(III) with the Angiotensin-Converting Enzyme Inhibitor Captopril

Captopril (CPT) is an inhibitor of angiotensin I converting enzyme, used as a medication for the treatment of people with high blood pressure, renal insufficiency, and cardiovascular diseases. It inhibits the angiogenesis process, vasoconstriction, and tumor metastasis. Some metal-captopril complexes exhibit antimicrobial activities. In the current work, the formation of the Cr^III-CPT complex was studied spectrophotometrically and potentiometrically in aqueous solution. Kinetics of Cr^III-CPT complex formation was spectrophotometrically studied over the pH range 3.20-4.20, at an ionic strength of 0.3 M at 30-50 °C. Cr^III-CPT complex formation was potentiometrically studied at 25 °C, where ligand protonation constants and complexes' overall stability constants were calculated. UV-vis absorption spectra were executed to confirm the complex formation. Density functional theory and molecular dynamics simulation were performed to search the geometries of the Cr^III-CPT complex. Atoms in molecules and interaction region indicator calculations are used to investigate intermolecular interactions for the formation of Cr^III-CPT complex. The antimicrobial activity of the CPT ligand and Cr^III-CPT complex on the prevention and control of environmental pathogenic bacteria, as tested on both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli) via agar disc diffusion method, assess the ability to use as an antimicrobial agent. CPT had shown good antimicrobial activity against both types of bacteria, which had increased slightly the zone of inhibition in Cr-CPT that indicates the increased efficacy due to Cr(III) antimicrobial activity via its oxidative damage to the bacterial cell wall. No previous study tested the CPT antimicrobial activity against Gram-positive ones such as S. aureus.

Bioremediation of hexavalent-chromium contaminated groundwater: Microcosm, column, and microbial diversity studies

Sulfate reducing bacteria (SRB) have the capability of bioreducing hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] under sulfate-reducing conditions for toxicity reduction. However, a high amount of sulfate addition would cause elevated sulfide production, which could inhibit the growth of SRB and result in reduced Cr(VI) bioreduction efficiency. A slow release reagent, viscous carbon and sulfate-releasing colloidal substrates (VCSRCS), was prepared for a long-lasting carbon and sulfate supplement. In the column study, VCSRCS was injected into the column system to form a VCSRCS biobarrier for Cr(VI) containment and bioreduction. A complete Cr(VI) removal was observed via the adsorption and bioreduction mechanisms in the column with VCSRCS addition. Results from X-ray diffractometer analyses indicate that Cr(OH)_3(s) and Cr₂O_3(s) were detected in precipitates, indicating the occurrence of Cr(VI) reduction followed by Cr(III) precipitation. Results from the Fourier-transform infrared spectroscopy analyses show that cell deposits carried functional groups, which could adsorb Cr. Addition of VCSRCS caused increased populations of total bacteria and dsrA, which also enhanced Cr(VI) reduction. Microbial diversity results indicate that VCSRCS addition resulted in the growth of Cr(VI)-reducing bacteria including Exiguobacterium, Citrobacter, Aerococcus, and SRB. Results of this study will be helpful in developing an effective and green VCSRCS biobarrier for the bioremediation of Cr(VI)-polluted groundwater.

Associations of plasma metal concentrations with incident dyslipidemia: Prospective findings from the Dongfeng-Tongji cohort

Metal exposures are ubiquitous around the world, while it is lack of prospective studies to evaluate the associations of exposure to multiple metal/metalloids with incident dyslipidemia. A total of 2947 participants without dyslipidemia at baseline were included in the analyses. We utilized inductively coupled plasma mass spectrometry to measure the baseline plasma metal concentrations. Unconditional logistic regression models were applied to estimate the relations between plasma metals and risk of incident dyslipidemia, and principal component analysis was performed to extract principal components of metals. During 5.01 ± 0.31 years of follow-up, 521 subjects were diagnosed with incident dyslipidemia. After multivariable adjustment, the odds ratios (ORs) of dyslipidemia comparing the highest quartiles to the lowest were 1.58 (95% CI: 1.20, 2.08; P_trend = 0.001) for aluminum, 1.34 (95% CI: 1.03, 1.75; P_trend = 0.03) for arsenic, 1.44 (1.09, 1.91; P_trend = 0.03) for strontium, and 1.47 (95% CI: 1.09, 2.00; P_trend = 0.005) for vanadium. The four metals also showed significant associations with the subtypes of dyslipidemia, including low HDL-C and high LDL-C. The first principal component, which mainly represented aluminum, arsenic, barium, lead, vanadium, and zinc, was associated with increased risk of incident dyslipidemia, and the adjusted OR was 1.40 (95% CI: 1.07, 1.84; P_trend = 0.02) comparing extreme quartiles. The study indicated that elevated plasma aluminum, arsenic, strontium, and vanadium concentrations were associated with a higher incidence of dyslipidemia. These findings highlight the importance of controlling metal exposures for dyslipidemia prevention.

Effects of chromium supplementation on lipid profile in patients with type 2 diabetes: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND

The purpose of this study was to determine the influence of chromium supplementation on lipid profile in patients with type 2 diabetes mellitus (T2DM).

METHODS

A systematic search was performed in Scopus, Embase, Web of Science, the Cochrane library and PubMed databases to find randomized controlled trials (RCTs) related to the effect of chromium supplementation on lipid profile in patients with T2DM, up to June 2020. Meta-analyses were performed using the random-effects model, and I² index was used to evaluate heterogeneity.

RESULTS

The primary search yielded 725 publications. 24 RCTs (with 28 effect size) were eligible. Our meta-analysis indicated that chromium supplementation resulted in a significant decrease in serum levels of triglyceride (TG) (MD: -6.54 mg/dl, 95 % CI: -13.08 to -0.00, P = 0.050) and total cholesterol (TC) (WMD: -7.77 mg/dl, 95 % CI: -11.35 to -4.18, P < 0.001). Furthermore, chromium significantly increases high-density lipoprotein (HDL) (WMD: 2.23 mg/dl, 95 % CI: 0.07-4.40, P = 0.043) level. However, chromium supplementation did not have significant effects on low-density lipoprotein (LDL) (WMD: -8.54 mg/dl, 95 % CI: -19.58 to 2.49, P = 0.129) level.

CONCLUSION

Chromium supplementation may significantly improve lipid profile in patients with T2DM by decreasing TG and TC and increasing HDL. However, based on our analysis, chromium failed to affect LDL. It should be noted that the lipid-lowering properties of chromium supplementation were small and may not reach clinical importance.

Associations Between Serum Multiple Metals Exposures and Metabolic Syndrome: a Longitudinal Cohort Study

Although many studies have confirmed metabolic syndrome (MetS) is correlated with metal exposures, few studies have elucidated the associations of multiple metals with MetS risk. We aim to explore the relationship between serum 22 metals and MetS. We determined serum 22 metals using ICP-MS and used LASSO regression to select metals independently related with MetS to construct multiple-metals model. We further explored the dose-response relationship between positive metals and MetS by the restricted cubic spline regression. After screening by LASSO regression, serum 11 metals were selected to construct multiple-metals model in cross-sectional analysis, while 5 metals in longitudinal analysis. In the 11-metal model, only tin and zinc were associated with MetS in cross-sectional analysis (OR_tin = 2.22, 95% CI:1.43, 3.45; OR_zinc = 2.17, 95% CI: 1.42, 3.32; both P_trend < 0.05). Besides, the same results were found in the 5-metal model in longitudinal analysis (HR_tin = 1.66, 95% CI: 0.87, 3.17; HR_zinc = 1.83, 95% CI: 1.07, 3.14; both P_trend < 0.05). Moreover, there were positive linear relationships between serum tin and zinc concentrations and the increasing risk of MetS (both P_overall < 0.05, P_{non-linearity} > 0.05). Furthermore, the interaction between high tin and high zinc was also associated with increasing MetS risk (P_interaction < 0.05). We found that serum tin and zinc were independently and interactively associated with MetS in the southern Chinese men. Our results suggested that high tin and zinc may be the risk factors of MetS.

Influence of Physicochemical Properties and Parent Material on Chromium Fractionation in Soils

Chromium is an element that possess several oxidation states and can easily pass from one to another, so its behavior in soils is very complex. For this reason, determining its fate in the environment can be difficult. In this research work we tried to determine which factors affect the chromium fractionation in natural soils, conditioning chromium mobility. We paid special attention to the parent material. For this purpose, extraction experiments were carried out on spiked soils incubated for 50–60 days, using H2O, CaCl2 and diethylenetriaminepentaacetic acid (DTPA). The most efficient extraction rate in all soils was achieved using water, followed by CaCl2 and DTPA. We obtained models with an adjusted R2 of 0.8097, 0.8471 and 0.7509 for the H2O Cr, CaCl2 Cr and DTPA Cr respectively. All models were influenced by the amount of chromium added and the parent material: amphibolite and granite influenced the amount of H2O Cr extracted, and schist affected the other two fractions (CaCl2 and DTPA). Soil texture also played an important role in the chromium extraction, as well as the amounts of exchangeable aluminum and magnesium, and the bioavailable phosphorus. We concluded that it is possible to make relatively accurate predictions of the behavior of the different Cr fractions studied, so that optimized remediation strategies for chromium-contaminated soils can be designed on the basis of a physicochemical soil characterization.

Toxic metals in toenails as biomarkers of exposure: A review

Toenails have been used as biomarkers of exposure to toxic metals, but their validity for this purpose is not yet clear and might differ depending on the specific agent. To evaluate this issue, we reviewed the literature on: a) the time-window of exposure reflected by toenails; b) the reproducibility of toenail toxic-metal levels in repeated measures over time; c) their relationship with other biomarkers of exposure, and; d) their association with potential determinants (i.e. sociodemographic, anthropometric, or lifestyle characteristics) or with sources of exposure like diet or environmental pollution. Thus, we performed a systematic review, searching for articles that provided original data for levels of any of the following toxic metals in toenails: aluminum, beryllium, cadmium, chromium, mercury, nickel, lead, thallium and uranium. We identified 88 articles, reporting data from 67 different research projects, which were quite heterogeneous with regard to population profile, sample size and analytical technique. The most commonly studied metal was mercury. Concerning the time-window of exposure explored by toenails, some reports indicate that toenail cadmium, nickel and lead may reflect exposures that occurred 7-12 months before sampling. For repeated samples obtained 1-6 years apart, the range of intraindividual correlation coefficients of aluminum, chromium and mercury was 0.33-0.56. The correlation of toxic metal concentrations between toenails and other matrices was higher for hair and fingernails than for urine or blood. Mercury levels were consistently associated with fish intake, while other toxic metals were occasionally associated with specific sources (e.g. drinking water, place of residence, environmental pollution, and occupation). The most frequently evaluated health endpoints were cardiovascular diseases, cancer, and central nervous system diseases. Available data suggest that toenail mercury levels reflected long-term exposures and showed positive associations with fish intake. The lack of standardization in sample collection, quality control, analytical techniques and procedures - along with the heterogeneity and conflicting results among studies - mean it is still difficult to conclude that toenails are a good biomarker of exposure to toxic metals. Further studies are needed to draw solid conclusions about the suitability of toenails as biomarkers of exposure to toxic metals.

Down-regulation of ROCK2 alleviates ethanol-induced cerebral nerve injury partly by the suppression of the NF-κB signaling pathway

Chronic alcohol consumption leads to hippocampal neuronal impairment, which related to neuronal death, oxidative stress, and inflammatory response. Rho-associated protein kinase 2 (ROCK2) is a major regulator in the central nervous system injury. However, the effects of ROCK2 in ethanol-induced brain injury have not been explored. In this work, we investigated the neuroprotective effects and the mechanism of ROCK2 inhibition in vivo. Wistar rats were exposed to 37% ethanol for 8 weeks to establish brain injury models. Morris water maze test was performed to evaluate cognitive function, and we found that the down-regulation of ROCK2 reduced the escape latency and increased the passing times and percentage of time spent in the target quadrant of rats. The results of H&E staining and Nissl staining showed that ROCK2 inhibition alleviated the pathological injury induced by ethanol. PI staining and Western blot confirmed that inhibiting ROCK2 attenuated the neuronal death and apoptosis as reflected by the reduced PI-positive neurons and the decreased expression of cleaved-caspase-3 and cleaved-caspase-9. Furthermore, the down-regulation of ROCK2 ameliorated the oxidative stress and inflammatory response induced by ethanol in rats as reflected by the up-regulation of IL-10, SOD, and GSH and reduction of TNF-α, IL-6, and MDA respectively. Additionally, Western blot and EMSA analysis revealed that the down-regulation of ROCK2 suppressed the nuclear transfer of NF-κB p65. In conclusion, our data suggested that ROCK2 inhibition ameliorated ethanol-mediated hippocampal neuronal impairment by anti-apoptotic, anti-inflammatory, anti-oxidative effects at least partially through the suppression of the NF-κB pathway.

Lab-scale evaluation of the microbial bioremediation of Cr(VI): contributions of biosorption, bioreduction, and biomineralization

Bioremediation of Cr(VI) by microorganisms has attracted immense research interests. There are three different mechanisms for bioremediation of Cr(VI): biosorption, bioreduction, and biomineralization. Identifying the relative contributions of these different mechanisms to Cr(VI) bioremediation can provide valuable information to enhance the final result. This article explores the corresponding contributions of different mechanisms in the Cr(VI) bioremediation process. To obtain a deeper understanding of each bioremediation mechanism, the corresponding precipitation products were analyzed via different methods. Fourier transform infrared spectrometer (FTIR) analysis showed that Cr(VI) was adsorbed by functional groups in EPS to form a chelate compound. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis determined that the stable Cr(III) compounds and mineral crystals which contain chromium gradually formed during the bioremediation process. High-throughput sequencing technology was applied to monitor microbial community succession. The results showed that the total removal rate of Cr(VI) reached 77.64% in 56 days in 100 mg/L Cr(VI). Bioreduction was the major contributor to the final result, followed by biosorption and biomineralization; their proportions are 69.61%, 19.16%, and 11.23%, respectively. Besides, the high-throughput sequencing data indicated that reductive microorganisms were the dominant flora and that the relative abundance of different reductive microorganism types changes significantly. This work has clarified the contributions of different mechanisms during Cr(VI) bioremediation process and provided a new enhancement strategy for Cr(VI) bioremediation.Graphical abstract.

Plasma titanium level is positively associated with metabolic syndrome: A survey in China's heavy metal polluted regions

OBJECTIVE

Several heavy metals have been reported to be associated with metabolic syndrome(MetS) in general population, while effects of multiple metals exposure on MetS in residents living in heavy metal polluted regions have not been investigated. We aimed to assess the association of 23 metal levels and MetS among population living in China's heavy metal polluted regions.

METHODS

From August 2016 to July 2017, a total of 2109 eligible participants were consecutively enrolled in our study in Hunan province, China. The levels of plasma and urine metals were measured by inductively coupled plasma mass spectrometer (ICP-MS). MetS was defined by the criteria of the International Diabetes Federation. Multivariable regression models were applied to analysis the potential relationship.

RESULTS

In the overall population, crude model showed positive relationship of plasma titanium (Ti) with MetS and negative association of urine vanadium, iron, and selenium with MetS. After adjusted for potential confounders, only plasma Ti was positive associated with MetS (adjusted OR for Q4 versus Q1: 1.46; 95% CI: 1.06-1.99), and this positive correlation was explained by abdominal obesity (OR = 1.84, 95% CI: 1.41-2.39) and high triglycerides (OR = 2.23, 95% CI: 1.68-2.96). Further linear regression analysis revealed significant association of plasma Ti levels with waist circumference (β = 0.0056, 95% CI: 0.0004-0.0109, P = 0.036) and triglycerides (β = 0.0012, 95% CI: 0.0006-0.0019, P < 0.001), respectively.

CONCLUSION

High plasma Ti level was associated with increased risk of MetS via increasing waist circumference and triglycerides in people under high metal exposure.

Association of plasma chromium with metabolic syndrome among Chinese adults: a case-control study

Backgroud

Chromium has been suggested playing a role in alleviating diabetes, insulin resistance and lipid anomalies, but the effect on metabolic syndrome (MetS) in humans remains controversial.

Methods

We conducted a matched case-control study in a Chinese population, involving 2141 MetS cases and 2141 healthy controls, which were 1:1 matched by age (±2 years) and sex. Plasma chromium was measured by inductively coupled plasma mass spectrometry.

Results

Plasma chromium levels were lower in MetS group than in control group (mean: 4.36 μg/L and 4.66 μg/L, respectively, P < 0.001), and progressively decreased with the number of MetS components (P for trend < 0.001). After adjustment for potential confounding factors, the odds ratios (95% confidence intervals) for MetS across increasing quartiles of plasma chromium levels were 1 (reference), 0.84 (0.67–1.05), 0.76 (0.61–0.95), and 0.62 (0.49–0.78), respectively (P for trend < 0.001). For the components of MetS (high waist circumference, high triglycerides and high blood glucose), the odds ratios (95% confidence intervals) of the highest quartiles were 0.77 (0.61–0.95), 0.67 (0.55–0.80), and 0.53 (0.44–0.64), respectively (P for trend < 0.05).

Conclusions

Our results indicated that plasma chromium levels were inversely associated with MetS in Chinese adults. The association may be explained by the relations between plasma chromium levels and high waist circumference, and the triglycerides and blood glucose levels.

Associations of Heavy Metals with Metabolic Syndrome and Anthropometric Indices

Previous studies have revealed associations between heavy metals and extensive health problems. However, the association between heavy metals and metabolic problems remains poorly defined. This study aims to investigate relationships between heavy metals and metabolic syndrome (MetS), lipid accumulation product (LAP), visceral adiposity index (VAI), and anthropometric indices, including body roundness index (BRI), conicity index (CI), body adiposity index (BAI), and abdominal volume index (AVI). We conducted a health survey of people living in southern Taiwan. Six heavy metals were measured: lead (Pb) in blood and nickel (Ni), chromium (Cr), manganese (Mn), arsenic (As), and copper (Cu) in urine. A total of 2444 participants (976 men and 1468 women) were enrolled. MetS was defined according to the Adult Treatment Panel III for Asians. Multivariable analysis showed that participants with high urine Ni (log per 1 μg/L; odds ratio (OR): 1.193; 95% confidence interval (CI): 1.019 to 1.397; p = 0.028) and high urine Cu (log per 1 μg/dL; OR: 3.317; 95% CI: 2.254 to 4.883; p < 0.001) concentrations were significantly associated with MetS. There was a significant trend of a stepwise increase in blood Pb and urine Ni, As, and Cu according to the number of MetS components (from 0 to 5, a linear p ≤ 0.002 for trend). For the determinants of indices, urine Cu was positively correlated with LAP, BRI, CI, and VAI; blood Pb was positively correlated with BRI, BAI, and AVI; urine Ni was positively correlated with LAP. High urine Cu and urine Ni levels were significantly associated with MetS, and there was a significant trend for stepwise increases in blood Pb and urine Ni, As, and Cu, accompanied by an increasing number of MetS components. Furthermore, several indices were positively correlated with urine Cu, urine Ni, and blood Pb.

Mutation of MEDIATOR 18 and chromate trigger twinning of the primary root meristem in Arabidopsis

Plants adapt to soil injury and biotic stress via cell regeneration. In Arabidopsis, root tip damage by genotoxic agents, antibiotics, UV light and cutting induces a program that recovers the missing tissues through activation of stem cells and involves ethylene response factor 115 (ERF115), which triggers cell replenishment. Here, we show that mutation of the gene encoding an MED18 subunit of the transcriptional MEDIATOR complex and chromate [Cr(VI)], an environmental pollutant, synergistically trigger a developmental program that enables the splitting of the meristem in vivo to produce twin roots. Expression of the quiescent centre gene marker WOX5, auxin-inducible DR5:GFP reporter and the ERF115 factor traced the changes in cell identity during the conversion of single primary root meristems into twin roots and were induced in an MED18 and chromate-dependent manner during the root twinning events, which also required auxin redistribution and signalling mediated by IAA14/SOLITARY ROOT (SLR1). Splitting of the root meristem allowed dichotomous root branching in Arabidopsis, a poorly understood process in which stem cells may act to enable whole organ regeneration.

Incidence of Metabolic Syndrome in Young Japanese Adults in a 6-Year Cohort Study: The Uguisudani Preventive Health Large-Scale Cohort Study (UPHLS)

INTRODUCTION

To clarify the incidences of metabolic syndrome (MS) and risks in young Japanese adults by gender.

METHODS

A total of 58,901 adults who had undergone annual health check-ups in 2010 without a diagnosis of MS or missing data were divided into three age groups (20s through 40s) by gender. Participants were followed up for 6 years for new-onset MS according to Japanese criteria. The incidences of MS and risks were analyzed using the Cox proportional hazards model to adjust for confounding factors.

RESULTS

The incidences of MS per 1,000 person-years were 2.2, 5.5, and 10.2 for women aged in their 20s, 30s, and 40s, respectively, and 26.3, 40.5, and 57.4 in the respective men groups. Compared with the group aged in their 40s, the hazard ratios of new MS were 0.19 (95% confidence interval [CI], 0.13-0.29) for women in their 20s and 0.50 (95% CI, 0.41-0.61) for women in their 30s, and 0.46 (95% CI, 0.42-0.50) and 0.70 (95% CI, 0.66-0.73) for men in their 20s and 30s, respectively, after adjustment for lifestyle factors. For women, MS was associated with smoking in their 20s and 30s, and eating speed in their 30s, and for men, was associated with physical activity, eating speed, alcohol intake in their 20s and 30s, and smoking in their 30s.

CONCLUSION

Our findings suggest that the incidences of MS in the 20s and 30s are lower, but account for about 20-50% of women with MS and 50-70% of men with MS in their 40s. However, the data are not negligible and early lifestyle intervention for MS is necessary in young adults.

Dietary Patterns and Health Outcomes among African American Maintenance Hemodialysis Patients

The association between dietary patterns and health outcomes, such as quality of life (QOL), in maintenance hemodialysis (MHD) patients with certain racial backgrounds has not been studied in detail. QOL is a powerful outcome measure in which dietary patterns could be a modifying factor. This study is a secondary analysis examining the association between dietary patterns and health outcomes in 101 African American (AA) maintenance hemodialysis (MHD) patients participating in the Palm Tocotrienols in Chronic Hemodialysis (PATCH) study. Quality of life (QOL) was assessed using the Kidney Disease Quality of Life 36-item survey (KDQOL-36™). Blood samples were analyzed for lipids, lipoprotein subfractions, and inflammatory markers. Food intake was measured using six non-consecutive 24-h dietary recalls over 15 months. Implausible energy intake reports were screened out by comparing reported energy intake (rEI) with predicted total energy expenditure (pTEE). Cluster analysis, using the k-means algorithm, identified two distinct dietary patterns in the study population: a high "sugar sweetened beverage" pattern (hiSSB) and a low "sugar sweetened beverage pattern" (loSSB). In the hiSSB group, consumption of SSB accounted for ~28% of energy intake, while SSB represented only 9% of energy intake in the loSSB group. The hiSSB group was characterized by a higher intake of total calories, sugar and percentage of kilocalories from carbohydrates, whereas the percentage of kilocalories from protein and fat was lower. While additional micronutrient intakes differed between groups (vitamin C, zinc, chromium), these were significantly lower than recommended values in the entire cohort. Patients in the hiSSB group presented with lower high-density lipoprotein cholesterol (HDL-C), lower large HDL particles and smaller low density lipoprotein (LDL) particle diameters. Antidepressant usage was significantly higher in the hiSSB group. Patients in the hiSSB group scored lower across all five KDQOL domains and scored significantly lower in the mental composite domain. MHD patients following a hiSSB dietary pattern had smaller dense LDL particles, lower HDL-C, and a lower QOL. Suboptimal intakes of fruits, vegetables, and grains as well as key micronutrients were evident in both patterns.

Evaluation of the Effect of Fish Oil Alone and in Combination with a Proprietary Chromium Complex on Endothelial Dysfunction, Systemic Inflammation and Lipid Profile in Type 2 Diabetes Mellitus - A Randomized, Double-Blind, Placebo-Controlled Clinical Study

PURPOSE

This study was conducted to evaluate the effectiveness of fish oil alone and with an adjunct, a proprietary chromium complex (PCC), on cardiovascular parameters - endothelial dysfunction, lipid profile, systemic inflammation and glycosylated hemoglobin - in a 12-week randomized, double-blind, placebo-controlled clinical study in type 2 diabetes mellitus subjects.

PATIENTS AND METHODS

In this randomized, double-blind, parallel group study, 59 subjects in three groups completed the study: Group A, fish oil 2000 mg; Group B, fish oil 2000 mg + PCC 10 mg (200 µg of Cr³⁺); and Group C, fish oil 2000 mg + PCC 20 mg (400 µg of Cr³⁺) daily for 12 weeks (2000 mg of fish oil contained 600 mg of eicosapentaenoic acid [EPA] and 400 mg of docosahexaenoic acid [DHA], the omega-3 fatty acids). Endothelial function, by estimating reflection index (RI), biomarkers of oxidative stress (nitric oxide [NO], malondialdehyde [MDA], glutathione [GSH]) and inflammatory biomarkers (high-sensitivity C-reactive protein [hsCRP], intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1], endothelin-1) were evaluated at baseline, and 4 and 12 weeks. Lipid profile, platelet aggregation and glycosylated hemoglobin [HbA1c) were tested at baseline and 12 weeks. Any reported adverse drug reactions were recorded. Statistical analysis was performed using GraphPad Prism 8.

RESULTS

The present study shows that fish oil by itself, at a dose of 2000 mg (600 mg of EPA + 400 mg of DHA) per day, led to significant, but only modest, improvement in cardiovascular parameters (RI from -2.38±0.75 to -3.92±0.60, MDA from 3.77±0.16 to 3.74±0.16 nM/mL, NO from 30.60±3.18 to 32.12±3.40 µM/L, GSH from 568.93±5.91 to 583.95±6.53 µM/L; p≤0.0001), including triglyceride levels. However, when PCC was added to fish oil, especially at the 20 mg dose, there were highly significant improvements in all the parameters tested (RI from -2.04±0.79 to -8.73±1.36, MDA from 3.67±0.39 to 2.89±0.34 nM/mL, NO from 28.98±2.93 to 40.01±2.53 µM/L, GSH from 553.82±8.18 to 677.99±10.19 µM/L; p≤0.0001), including the lipid profile. It is noteworthy that the triglycerides were decreased significantly by addition of 20 mg of PCC although the dose of fish oil was only 2 g/day and the baseline triglyceride levels were only about 200 mg/dL. Fish oil alone did not significantly decrease the HbA1c, whereas the addition of 20 mg of PCC did.

CONCLUSION

Addition of PCC, especially at 20 mg dose, significantly improves the efficacy of fish oil in addressing cardiovascular risk factors compared to fish oil given alone.

Toenail Metal Exposures in Fishermen from Bodo City, Nigeria

We conducted exposure assessment using toenails from 20 fishermen living in Bodo City, a community of the Niger delta region in Nigeria. This community has been affected by over 4000 oil spills and environmental disasters. Fishing is the primary source of food and income for individuals in this community. Previous research in Bodo City found elevated metal levels in fish. Toenails were used as a biomarker to investigate the feasibility for use in risk assessment studies in developing countries. The toenails collected had significantly higher manganese levels (median 5.8 µg/g) and lead levels (median 0.98 µg/g) than those reported in more developed countries, comparable levels to those from other low-middle incomes countries. These exposure levels are likely a direct result of exposures from the environmental disasters the community has experienced and would be related to increased risks for many diseases previously associated with heavy metal exposures.

Regulation Network of Sucrose Metabolism in Response to Trivalent and Hexavalent Chromium in Oryza sativa

The presence of chromium (Cr) in cultivated fields affects carbohydrate metabolism of rice (Oryza sativa L.) and weakens its productivity. Little is known about the molecular mechanism of sucrose metabolism underlying Cr stress response in rice plants. In the present study, the transcriptome map of sucrose metabolism in rice seedlings exposed to both trivalent and hexavalent chromium was investigated using Agilent 4 × 44K rice microarray analysis. Results indicated that Cr exposure (3 days) significantly (p < 0.05) improved sucrose accumulation, and altered the activities of sucrose synthetase, sucrose phosphate phosphatase, and amylosynthease in rice tissues. We identified 119 differentially regulated genes involved in 17 sucrose metabolizing enzymes and found that gene responses in roots were significantly (p < 0.05) stronger than in shoots under both Cr(III) and Cr(VI) treatment. The network maps of gene regulation responsible for sucrose metabolism in rice plants provide a theoretical basis for further cultivating Cr-resistant rice cultivars through molecular genetic improvement.

Association of urinary metal profiles with serum uric acid: a cross-sectional study of traffic policemen in Wuhan, China

OBJECTIVES

Serum uric acid (SUA) is both a strong antioxidant and one of the key risk factors of cardiovascular diseases (CVDs). We aimed to investigate the associations of urinary metal profile with SUA in traffic policemen in Wuhan, China.

DESIGN

A cross-sectional study was carried out in traffic policemen.

SETTING

A seriously polluted Chinese city.

PARTICIPANTS

A total of 186 traffic policemen were recruited in this study. About 56 of them worked in the logistics department and the other 130 maintained traffic order or dealt with traffic accidents on the roads. All these subjects had worked as a policeman for at least 1 year.

MAIN OUTCOME MEASURES

SUA.

RESULTS

The significantly negative association of lead with SUA was consistent between single-metal and multiple-metal models (p=0.004 and p=0.020, respectively). Vanadium, chromium and tin were reversely associated with SUA levels in the single-metal models after false discovery rate (FDR) adjustment (all P_{_FDR} < 0.05). One IQR increase in vanadium, chromium, tin and lead was associated with 26.9 µmol/L (95% CI -44.6 to -9.2; p=0.003), 27.4 µmol/L (95% CI -46.1 to -8.8; p=0.004), 11.2 µmol/L (95% CI -18.9 to -3.4; p=0.005) and 16.4 µmol/L (95% CI -27.6 to -5.2; p=0.004) decrease in SUA, respectively. Significant interaction between smoking and vanadium on decreased SUV was found (p_{for interaction} = 0.007 and p_{_FDR} = 0.028).

CONCLUSIONS

Urinary vanadium, chromium, tin and lead were negatively associated with SUA. Vanadium and cigarette smoking jointly affected SUA levels. Further studies are needed to replicate these findings and to investigate the potential mechanisms.

The cross-sectional and longitudinal associations of chromium with dyslipidemia: A prospective cohort study of urban adults in China

Chromium exposure can induce altered lipoprotein metabolism in animals, but the health effects of chromium on dyslipidemia in humans have not been fully evaluated. In this study, we aimed to investigate the cross-sectional and longitudinal effects of urinary chromium on lipid levels and dyslipidemia risk among urban adults from two cities in China. A total of 3762 urban adults from the Wuhan-Zhuhai cohort were included in the initial investigation, and followed up three years later. Urinary chromium concentration was measured at baseline and repeated at follow-up. Associations of urinary chromium concentration with lipid levels and risk of dyslipidemia were analyzed by generalized linear and binary logistic regression models, respectively. We found significant relationships between increased urinary chromium concentration and both reduced triglyceride (TG) level and elevated high-density lipoprotein cholesterol (HDL-C) level at baseline and follow-up. In the cross-sectional analysis, each 1-unit increase in log-transformed urinary chromium was associated with a 0.25 mmol/L decrease in TG and a 0.05 mmol/L increase in HDL-C (P < 0.05); also, downward trends for odds ratios of hyperTG (TG level ≥ 1.7 mmol/L) and hypoHDL-C (HDL-C level < 1.0 mmol/L) were significantly associated with increasing quartiles of urinary chromium (P trend < 0.05). In the longitudinal analysis, each 1-unit increase in log-transformed urinary chromium concentration was associated with a 3% and 6% decrease in the risk of developing hyperTG and hypoHDL-C, respectively (P > 0.05). Our study indicated that significant dose-response relationships between urinary chromium concentration and lipid levels were observed at baseline and at follow-up.

The adsorptive removal of chromium (VI) in aqueous solution by novel natural zeolite based hollow fibre ceramic membrane

Adsorption is one of the most efficient ways to remove heavy metal from wastewater. In this study, the adsorptive removal of hexavalent chromium, Cr (VI) from aqueous solution was investigated using natural zeolite, clinoptilolite, in the form of hollow fibre ceramic membrane (HFCM). The HFCM sample was prepared using phase inversion-based extrusion technique and followed by sintering process at different sintering temperatures in the range of 900-1050 °C. The fabricated HFCM was characterised using scanning electron microscopy (SEM), contact angle, water permeability, and mechanical strength for all HFCMs sintered at different temperatures. The adsorption and filtration test of Cr (VI) were performed using an in-house water permeation set up with a dead-end cross-flow permeation test. An asymmetric structure with sponge- and finger-like structures across the cross-section of HFCM was observed using SEM. Based on the characterisation data, 1050 °C was chosen to be the best sintering temperature as the water permeability and mechanical strength of this HFCM were 29.14 L/m²∙h and 50.92 MPa, respectively. The performance of the HFCM in adsorption/filtration was 44% of Cr (VI) removal at the Cr (VI) concentration of 40 mg/L and pH 4. In addition, the mathematical model was also performed in simulating the experimental data obtained from this study. All in all, the natural zeolite-based HFCM has a potential as a single-step Cr (VI) removal by membrane adsorption for the wastewater treatment.

Localization and Speciation of Chromium in Coptis chinensis Franch. using Synchrotron Radiation X-ray Technology and Laser Ablation ICP-MS

Coptis chinensis Franch. is one of the most important medicinal plants globally. However, this species contains relatively high concentrations of chromium (Cr) which potentially detrimental to human health. It is important to understand Cr localization and speciation in order to evaluate its accumulation and transportation mechanisms and minimize Cr transfer to humans. As little previous work in this area has been carried out, we utilized synchrotron radiation microscopic X-ray fluorescence (SR-μXRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to spatially locate Cr, X-ray absorption near-edge spectroscopy (XANES) to analyze Cr speciation, and inductively coupled plasma mass spectrometry (ICP-MS) to detect Cr subcellular concentration. Micromapping results showed that Cr was distributed predominantly within the vascular cylinder, the periderm and some outer cortex, and the cortex and some vascular bundles in root, rhizome, and petiole, respectively. XANES data showed that Cr(VI) can be reduced to Cr(III) when grown with Cr(VI), and yielded a novel conclusion that this plant contain elemental chromium. ICP-MS data showed that Cr was primarily compartmentalized in cell walls in all tissues. The new insights on Cr accumulation in C. chinensis Franch. provide a theoretical basis for the evaluation of Cr in other medicinal plants.

Toenail Chromium Concentration and Metabolic Syndrome among Korean Adults

Although in vivo and in vitro studies have shown that chromium has protective effects against metabolic diseases, few studies have examined this association in humans. The present study examined chronic chromium (Cr) exposure among Koreans based on the measurement of toenail Cr concentrations, and analyzed the associations between toenail Cr concentrations and metabolic syndrome (MetS) and its components. We conducted a cross-sectional analysis using baseline data from the prospective cohort study in the Yeungnam area of South Korea that included 232 men and 268 women. Toenail Cr concentration was quantified by neutron activation analysis, and metabolic biomarker levels were obtained through medical examinations. The odd ratios (OR) of prevalent MetS and its components in correlation with Cr concentrations were calculated using multivariable logistic regression. After multiple confounding variables were adjusted for, participants with higher concentrations of Cr had a prevalence rate of MetS similar to those with lower concentrations (OR, 1.84; 95% confidence interval, 0.65-5.23). Our results do not support an association between long-term exposure to Cr and a lower prevalence of MetS in Koreans, whose Cr concentrations are relatively low compared to those of populations in Europe and the United States.

Chromium speciation, bioavailability, uptake, toxicity and detoxification in soil-plant system: A review

Chromium (Cr) is a potentially toxic heavy metal which does not have any essential metabolic function in plants. Various past and recent studies highlight the biogeochemistry of Cr in the soil-plant system. This review traces a plausible link among Cr speciation, bioavailability, phytouptake, phytotoxicity and detoxification based on available data, especially published from 2010 to 2016. Chromium occurs in different chemical forms (primarily as chromite (Cr(III)) and chromate (Cr(VI)) in soil which vary markedly in term of their biogeochemical behavior. Chromium behavior in soil, its soil-plant transfer and accumulation in different plant parts vary with its chemical form, plant type and soil physico-chemical properties. Soil microbial community plays a key role in governing Cr speciation and behavior in soil. Chromium does not have any specific transporter for its uptake by plants and it primarily enters the plants through specific and non-specific channels of essential ions. Chromium accumulates predominantly in plant root tissues with very limited translocation to shoots. Inside plants, Cr provokes numerous deleterious effects to several physiological, morphological, and biochemical processes. Chromium induces phytotoxicity by interfering plant growth, nutrient uptake and photosynthesis, inducing enhanced generation of reactive oxygen species, causing lipid peroxidation and altering the antioxidant activities. Plants tolerate Cr toxicity via various defense mechanisms such as complexation by organic ligands, compartmentation into the vacuole, and scavenging ROS via antioxidative enzymes. Consumption of Cr-contaminated-food can cause human health risks by inducing severe clinical conditions. Therefore, there is a dire need to monitor biogeochemical behavior of Cr in soil-plant system.

Inverse Association of Plasma Chromium Levels with Newly Diagnosed Type 2 Diabetes: A Case-Control Study

Chromium has long been known as an enhancer of insulin action. However, the role of chromium in the development of type 2 diabetes mellitus (T2DM) in humans remains controversial. The current study aimed to examine the associations of plasma chromium levels with T2DM and pre-diabetes mellitus (pre-DM). We conducted a case-control study involving 1471 patients with newly diagnosed T2DM, 682 individuals with newly diagnosed pre-DM, and 2290 individuals with normal glucose tolerance in a Chinese population from 2009 to 2014. Plasma chromium was measured by inductively coupled plasma mass spectrometry. Plasma chromium levels were lower in the T2DM and pre-DM groups than in the control group (median: 3.68 μg/L, 3.61 μg/L, 3.97 μg/L, respectively, p < 0.001). After adjustment for potential confounding factors, the odds ratios (95% confidence interval) for T2DM across increasing quartiles of plasma chromium levels were 1 (referent), 0.67 (0.55–0.83), 0.64 (0.51–0.79), and 0.58 (0.46–0.73), respectively (p for trend <0.001). The corresponding odds ratios (95% confidence interval) for pre-DM were 1 (referent), 0.70 (0.54–0.91), 0.67 (0.52–0.88), and 0.58 (0.43–0.78), respectively (p for trend < 0.001). Our results indicated that plasma chromium concentrations were inversely associated with T2DM and pre-DM in Chinese adults.