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PubMed1998

The Structure of the Hydrated Gallium(III), Indium(III), and Chromium(III) Ions in Aqueous Solution. A Large Angle X-ray Scattering and EXAFS Study.

The structure of the hydrated gallium(III), indium(III), and chromium(III) ions has been determined in aqueous perchlorate and nitrate solutions by means of the large-angle X-ray scattering (LAXS) and extended X-ray absorption fine structure (EXAFS) techniques. The EXAFS studies have been performed over a wide concentration range, 0.005-1.0 mol.dm(-)(3) (2.6 mol.dm(-)(3) for chromium(III)), while the LAXS studies are restricted to concentrated solutions, ca. 1.5 mol.dm(-)(3). All three metal ions were found to coordinate six water molecules, each of which are hydrogen bonded to two water molecules in a second hydration sphere. The metal-oxygen bond distance in the first hydration sphere of the gallium(III), indium(III), and chromium(III) ions was determined by LAXS and EXAFS methods to be 1.959(6), 2.131(7), and 1.966(8) Å. The LAXS data gave mean second sphere M.O distances of 4.05(1), 4.13(1), and 4.08(2) Å for the gallium(III), indium(III), and chromium(III) ions, respectively. The perchlorate ion was found to be hydrogen bonded to 4.5(7) water molecules with the O.O distance 3.05(2) Å and Cl.O 3.68(3) Å. Analyses of the Ga, In, and Cr K-edge EXAFS data of the aqueous perchlorate and nitrate solutions showed no influence on the first shell M-O distance by a change of concentration or anion. The minor contribution from the second sphere M.O distance is obscured by multiple scattering within the tightly bonded first shell. EXAFS data for the alum salts CsM(SO(4))(2).12H(2)O, M = Ga or In, showed the M-O bond length of the hexahydrated gallium(III) and indium(III) ions to be 1.957(2) and 2.122(2) Å, respectively.

Journal Article↗
PubMed2003

Chromium picolinate for reducing body weight: meta-analysis of randomized trials.

The aim of this meta-analysis was to assess the evidence of chromium picolinate for reducing body weight. Literature searches were conducted on Medline, Embase, The Cochrane Library, Amed and Ciscom. Nine experts and four manufacturers of commercial preparations containing chromium picolinate were asked to contribute published and unpublished studies. There were no restrictions regarding the language of publication. The screening of studies, selection, data extraction, validation and the assessment of methodological quality were performed independently by two reviewers. To be included, studies were required to state that they were randomized, double-blind and placebo-controlled, and report on body weight. Ten trials met all inclusion criteria and provided data, which were suitable for statistical pooling. For body weight a significant differential effect was found in favour of chromium picolinate (weighted mean difference: -1.1 kg; 95% confidence interval (CI): -1.8 to -0.4 kg, n=489). Sensitivity analysis suggests that this effect is largely dependent on the results of a single trial (weighted mean difference: -0.9 kg; 95% CI: -2.0 to 0.2 kg, n=335). Three of the reviewed trials reported on adverse events, indicating their absence in the treatment groups. In conclusion, our meta-analysis suggests a relatively small effect of chromium picolinate compared with placebo for reducing body weight. The clinical relevance of the effect is debatable and the lack of robustness means that the result has to be interpreted with caution.

Dietary Supplements↗
PubMed2002

Reversible dimerization of C60 molecules in the crystal structure of the bis(arene)chromium fulleride [Cr(C7H8)]2C60.

Bis(toluene)chromium fulleride, [Cr(C(7)H(8))(2)]C(60), has been synthesized as a black microcrystalline powder from C(60) and [Cr(C(7)H(8))(2)] in toluene. [Cr(C(7)H(8))(2)]C(60) is an ionic compound in which the fullerene is negatively charged and the bis(toluene)chromium molecule positively charged. At T = 250 K a reversible first-order phase transition from a primitive cubic high-temperature phase to a triclinic low-temperature phase occurs. The high-temperature phase [Pm3 macro m, a = 9.9840 (1) A, T = 295 K] is composed of dynamically disordered fulleride anions and bis(toluene)chromium(I) cations in a CsCl-type arrangement. The triclinic low-temperature modification [P1 macro, a = 13.6414 (8), b = 13.8338 (7), c = 13.8548 (7) A, alpha = 91.830 (3), beta = 116.776 (2), gamma = 119.333 (2) degrees, T = 235 K] consists of ordered C(60) dimers and two crystallographically distinct bis(toluene)chromium entities.

Journal Article↗
PubMed2004

An informatics search for the low-molecular weight chromium-binding peptide.

BACKGROUND: The amino acid composition of a low molecular weight chromium binding peptide (LMWCr), isolated from bovine liver, is reportedly E:G:C:D::4:2:2:2, though its sequence has not been discovered. There is some controversy surrounding the exact biochemical forms and the action of Cr(III) in biological systems; the topic has been the subject of many experimental reports and continues to be investigated. Clarification of Cr-protein interactions will further understanding Cr(III) biochemistry and provide a basis for novel therapies based on metallocomplexes or small molecules. RESULTS: A genomic search of the non-redundant database for all possible decapeptides of the reported composition yields three exact matches, EDGEECDCGE, DGEECDCGEE and CEGGCEEDDE. The first two sequences are found in ADAM 19 (A Disintegrin and Metalloproteinase domain 19) proteins in man and mouse; the last is found in a protein kinase in rice (Oryza sativa). A broader search for pentameric sequences (and assuming a disulfide dimer) corresponding to the stoichiometric ratio E:D:G:C::2:1:1:1, within the set of human proteins and the set of proteins in, or related to, the insulin signaling pathway, yields a match at an acidic region in the alpha-subunit of the insulin receptor (-EECGD-, residues 175-184). A synthetic peptide derived from this sequence binds chromium(III) and forms a metal-peptide complex that has properties matching those reported for isolated LMWCr and Cr(III)-containing peptide fractions. CONCLUSION: The search for an acidic decameric sequence indicates that LMWCr may not be a contiguous sequence. The identification of a distinct pentameric sequence in a significant insulin-signaling pathway protein suggests a possible identity for the LMWCr peptide. This identification clarifies directions for further investigation of LMWCr peptide fractions, chromium bio-coordination chemistry and a possible role in the insulin signaling pathway. Implications for models of chromium action in the insulin-signaling pathway are discussed.

Journal Article↗
PubMed2006

Effects of chromium supplementation on glycogen synthesis after high-intensity exercise.

PURPOSE: Chromium enhances insulin signaling and insulin-mediated glucose uptake in cultured cells. We investigated the effect of chromium on glycogen synthesis and insulin signaling in humans. METHODS: Sixteen overweight men (BMI = 31.1 +/- 3.0 kg.m) were randomly assigned to supplement with 600 microg.d chromium as picolinate (Cr; N = 8) or a placebo (Pl; N = 8). After 4 wk of supplementation, subjects performed a supramaximal bout of cycling exercise to deplete muscle glycogen, which was followed by high-glycemic carbohydrate feedings for the next 24 h. Muscle biopsies were obtained at rest, immediately after exercise, and 2 and 24 h after exercise. RESULTS: Elevations in glucose and insulin during recovery were not different, but the lactate response was significantly higher in Cr. There was a significant depletion in glycogen immediately after exercise, an increase at 2 h, and a further increase above rest at 24 h (P < 0.05). The rate of glycogen synthesis during the 2 h after exercise was not different between groups (Cr: 25.8 +/- 8.0 and Pl: 17.1 +/- 4.7 mmol.kg.h). Glycogen synthase activity was significantly increased immediately after exercise in both groups. Muscle phosphatidylinositol 3-kinase (PI 3-kinase) activity decreased immediately after exercise and increased at 2 h (P < 0.05), with a trend for a lower PI 3-kinase response in Cr (P = 0.08). CONCLUSIONS: Chromium supplementation did not augment glycogen synthesis during recovery from high-intensity exercise and high-carbohydrate feeding, although there was a trend for lower PI 3-kinase activity.

Adult↗
PubMed2005

Effects of dietary combination of chromium and biotin on growth performance, carcass characteristics, and oxidative stress markers in heat-distressed Japanese quail.

Environmental stress causes adverse effects in performance and antioxidant status of poultry. Dietary chromium supplementation promotes the growth rate and feed efficiency of growing poultry and these beneficial effects of chromium appear to be greater under stress. Biotin, a member of the vitamin B complex, is involved in the metabolism of carbohydrates, fats, and proteins. In a previous experiment, we examined the effects of chromium picolinate (CrPic) as a chromium source in birds subjected to high environmental temperature and the data showed that supplementation with CrPic ameliorated the deletorious effect of stress. The study was conducted to determine the effects of a supplementation of combination of CrPic and biotin (Diachrome ) on performance, carcass characteristics, levels of oxidative stress markers, serum cholesterol, and glucose concentrations in Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature of 34 degrees C. Two hundred forty Japanese quail (10 d old) were randomly assigned to 8 treatment groups consisting of 10 replicates of 3 birds. The birds were kept in a temperature-controlled room at 22 degrees C (thermo-neutral [TN] groups) or 34 degrees C (for 8 h/d; 09.00 am to 05.00 pm; heat-stress [HS] groups). Birds were fed either a basal (control) diet (TN and HS) or the basal diet supplemented with either 1, 2, or 4 mg of Diachrome/kg of diet. Heat exposure decreased performance when the basal diet was fed (p = 0.001). Diachrome supplementation increased feed intake (p = 0.001), body weight (p = 0.05), feed efficiency (p = 0.01), and carcass traits (p 0.05) the variables measured, with the exception of a reduction in serum cholesterol and glucose. Results of the present study suggest that Diachrome can be considered a protective dietary supplement by reducing the negative effects of high environment temperature on performance and oxidative stress in quail.

Animal Feed↗
PubMed2005

Adipose tissue metabolism and production responses to calcium propionate and chromium propionate.

The objective was to determine action of calcium propionate and chromium propionate on lipogenesis and lipolysis in adipose tissue, dry matter (DM) intake, milk production and composition, and serum glucose and free fatty acids in Holstein dairy cattle treated from 21 d prepartum to 35 d postpartum. Twelve multiparous animals were assigned to each treatment: control (C), calcium propionate (CaP, 0.125 kg/d), chromium propionate (CrP, 10 mg of trivalent Cr/d), and both. All animals were switched to control at 36 days in milk (DIM) and the trial continued to 90 DIM. Biopsies of adipose tissue were taken at -7, 14, 28, and 56 d from calving. Control intake prepartum was 10.6 +/- 2 kg/d. Calcium propionate increased DM intake 11% prepartum and 13% postpartum; CrP increased DM intake 7 and 16%; and the combination treatment had no effect. Milk yield was 44.2 kg/d for controls and 46.8 kg/d for d 1 to 90 for CrP-treated cows. Adipose tissue lipogenesis in cows treated with either CaP or CrP was 1.25 to 78 times as fast as controls from 14 to 56 d and had returned to prepartum rates by 56 d. From 14 to 28 d, basal lipolysis in CaP- or CrP-treated cows ranged from 27 to 102% of control, whereas stimulated lipolysis was 61 to 113% of control. Milk fat yield was 92 to 95% of control on calcium and chromium propionate; the difference was similar to the net reduction in adipose lipolysis. Milk lactose, protein, and solids-not-fat did not differ among treatments. Providing a small amount of gluconeogenic precursors may reduce net lipolysis, allowing increased feed intake and milk production. The effect is thought to be through chromium acting to increase glucose flux into adipocytes.

Adipose Tissue↗
PubMed2001

The effect of chromium picolinate on muscular strength and body composition in women athletes.

Fifteen women softball athletes were randomly divided into 2 groups, the chromium treatment group (n = 8) and the placebo control group (n = 7) to examine the effect of chromium, in the form of chromium picolinate (CrPic) supplementation, on muscular strength, body composition (body weight, percent body fat, and lean body mass), and urinary excretion. The CrPic supplementation consisted of a 500 ug dosage taken once per day. All participants trained 3 times per week with 2-3 sets of 8-12 repetitions at 80% of 1 repetition maximum (1RM) using variable resistance machines and free weights. No significant (p < 0.05) differences in muscular strength or body composition were found after 6 weeks of resistance training. In addition, chromium excretion (microg per 24 every hours) was examined and increased significantly with the treatment group after the 6-week period.

Adolescent↗
PubMedDate not supplied

Chromate allergy: total chromium and hexavalent chromate in the air.

This is a study on atmospheric concentration of total chromium and hexavalent chromate and its role in chromate sensitivity. Air concentration of total chromium and hexavalent chromate in a construction factory, a busy city area, a suburban area, a residential area, and a heavy industrial area were measured by air sampling pumps. Hexavalent chromate was not detected in any sampled areas. Two (concreting areas) of 8 locations in the construction factory had total chromium of 0.2 and 2.3 micrograms/m3 in the atmosphere. It appeared that the atmospheric concentration of total chromium and hexavalent chromate was negligible. These findings indicate that unexplained chromate sensitivity, as so often seen in patients attending a contact dermatitis clinic, is not attributable to exposure to hexavalent chromate in the air.

Chromates↗
PubMed1978

Contact sensitivity to trivalent chromium compounds.

The investigations confirmed the known fact that for skin tests larger amounts of trivalent chromium compounds are necessary than those of potassium dichromate. It was also observed that some patients react to relatively higher Cr VI and lower Cr III concentrations and others vice versa. Chromium nitrate and chloride release and that of potassium dichromate was determined and converted to the chromium content in the concentrations used for skin tests. It was found that Cr III compounds cannot be used for skin tests in a 0,5% concentration if only because they are released in undeterminable amounts. Release of Cr III and potassium dichromate from bases containing the same amount of substance when converted to chromium demonstrated that the different release of Cr III is not an additional cause of the fact that much higher concentrations of Cr III compounds have to be used for patch tests than those of Cr VI compounds.

Chromates↗
PubMed1995

Effects of chromium picolinate on body composition.

OBJECTIVE: This study explored the efficacy of chromium picolinate as a fat-reduction aid for obese individuals enrolled in a physical exercise program. EXPERIMENTAL DESIGN: The study employed a double-blind, placebo-controlled protocol and lasted for 16 weeks. SETTING: The physical conditioning programs were conducted on Navy bases (gymnasium, athletic field, etc.) and met a minimum of three times per week for at least 30 minutes of aerobic exercise. PARTICIPANTS: Participants were healthy, active-duty Navy personnel (79 men, 16 women) who exceeded the Navy's percent body fat standards of 22% fat for men, 30% for women. Mean age was 30.3 years; racial distribution was 76% white, 16% black, and 8% other. Comparisons between the 95 study completers and the 109 dropouts revealed no significant differences in demographics or baseline percent body fat. INTERVENTIONS: Bottles of capsules containing either 400 micrograms chromium picolinate or a placebo were distributed to the designated individuals by their fitness program coordinator. Participants took one capsule per day and kept a log of their daily exercise activities. They also completed a pre-post questionnaire concerning their health and lifestyle habits. MEASURES: Primary outcome measures were percent body fat, body weight, and lean body mass. Percent body fat was computed from body circumference measurements and height. Analyses controlled for diet and exercise. RESULTS: At the end of 16 weeks, the group as a whole had lost a small amount of weight and body fat. However, the chromium group failed to show a significantly greater reduction in either percent body fat or body weight, or a greater increase in lean body mass, than did the placebo group. CONCLUSIONS: It was concluded that chromium picolinate was ineffective in enhancing body fat reduction in this group and could not be recommended as an adjuvant to Navy weight-loss programs in general.

Adult↗
PubMed1984

Experimental bases for ascorbic acid therapy of poisoning by hexavalent chromium compounds.

The most frequent outcome of the usually transdermal absorption of hexavalent chromium compounds is uraemia due to tubular necrosis. We have confirmed earlier observations that this can be prevented by the immediate application of ascorbic acid (AA) with the aim of reducing Cr(VI) to Cr(III). The spontaneous reducing capacity of samples of serum and plasma for Cr(VI) compounds was polarographically determined to be about 2 ppm. Addition of AA in doses of 50 to 1000 ppm led to a rapid and dose-dependent reduction of chromium(VI), which was studied on the concentration level of 5 ppm. For example in the presence of 1000 ppm AA, five ppm chromium(VI) fade to 0.7 ppm within 20 min and to undetectable concentrations after 40 min. These experiments demonstrate the effectiveness of AA for the treatment of Cr(VI) poisoning. Reduction is increased and accelerated by AA and the resulting Cr(III)-protein complexes are non-toxic and can be excreted with the urine. Early and repeated high i.v. doses of AA are recommended as the therapy of choice for Cr(VI) poisoning. In cases of delayed medical treatment, AA should be immediately applied orally.

Ascorbic Acid↗
PubMed1984

Toxicity of hexavalent chromium to the alveolar macrophage in vivo and in vitro.

In vivo and in vitro systems were used to evaluate hexavalent chromium toxicity to alveolar macrophages. Rat alveolar macrophages were exposed to 2 micrograms calcium chromate (CaCrO4, insoluble) or 2 micrograms chromium trioxide (CrO3, soluble) in live animals, in vivo, and in tissue culture, in vitro, collected by lavage from the lung. Chemiluminescence and oxygen consumption were measured as indicators of toxicity. Trypan blue dye exclusion was used to determine macrophage viability. In vivo exposure of the macrophage to either chromium compound showed no toxic effects at a 2-micrograms dose. Macrophages exposed in tissue culture, however, had values significantly different from controls. The untreated controls for both exposure methods were compared to evaluate differences resulting from methods alone.

Animals↗
PubMed1992

The genotoxicity of chromium(VI) oxide in the wing spot test of Drosophila melanogaster is over 90% due to mitotic recombination.

Chromium(VI) oxide and chromium(III) chloride were tested in the wing somatic mutation and recombination test (SMART) in Drosophila melanogaster according to standard procedures. The hexavalent compound was highly genotoxic in both chronic and acute treatments whereas the trivalent one was clearly negative. Further analysis of wings carrying an inversion chromosome which eliminates all recombination events showed that over 90% of the spots induced by chromium(VI) oxide are due to mitotic recombination.

Animals↗
PubMed2005

Vitamins deficiency in developing chick during chromium intoxication and protection thereof.

Deficiency of various vitamins in postnatally developing chick during chromium intoxication and their recovery during vitamins (B and E) and glutathione therapies has been investigated. Study was concentrated on liver, kidney, muscles and serum. Newly hatched chicks were reared in laboratory. They were treated with a daily dose of 10mg/kg/day potassium dichromate from 2nd to 8th day of their age. Thereafter, one group was sacrificed on 9th day. Second group was kept without intoxication for another 7 days and sacrificed on 16th day. Three groups of chromium pretoxicated animals were exposed to therapeutic agents like vitamins (B and E) and glutathione for another 7 days. These animals were sacrificed on 16th day of their age along with control. Study showed chromium intoxication decreases vitamins (B(1), B(2), B(6) and E) in all the tissues and serum. The maximum decrease was recorded in serum. The 7 days pretoxicated animals kept without any treatment for 7 days revealed a slow increase of vitamins with few exceptions. Nevertheless, the recovery of vitamins was quick and significant during vitamins and glutathione therapy and in some cases control level was achieved.

Alanine Transaminase↗
PubMed1986

Rabbit alveolar macrophages after inhalation of hexa- and trivalent chromium.

Rabbits inhaled aerosols of hexavalent chromium (Na2CrO4) and trivalent chromium (Cr(NO3)3) at concentrations of 0.9 and 0.6 mg/m3 of the metal, respectively, for 4-6 weeks (5 days/week and 6 hr/day). Significantly more macrophages were obtained from the lungs of rabbits exposed to Cr(VI) but not from rabbits exposed to Cr(III) as compared with the controls. Macrophages from rabbits exposed to Cr(III) showed several conspicuous changes. About one-third of the macrophages contained round dark inclusions, 0.5-1.5 micron diameter, rich in chromium. Most cells had very large lysosomes which contained membranous fragments of different sizes surrounded by a more homogeneous matrix. Laminated inclusions similar to the lamellar bodies in the type II cells increased in number as did the percentage of cells with a smooth cell surface. Also macrophages from rabbits exposed to Cr(VI) showed morphological changes. The most pronounced one was enlarged lysosomes which contained short lamellae and electron-dense patchy inclusions. Only Cr(III) produced functional changes of the macrophages. The metabolic activity measured by reduction of nitroblue tetrazolium was increased and the phagocytic activity reduced.

Animals↗
PubMed2004

The use of air fuel cell cathodes to remove contaminants from spent chromium plating solutions.

Results from experiments using an impregnation-reduction (I-R) Pt / Nafion membrane electrode assembly (MEA) in an air fuel cell cathode to remove contaminants (Cu(II), Ni(II), and Fe(III)) from spent chromium electroplating baths are presented in this study. A platinum-carbon (Pt-C) / Nafion MEA and a Pb planar cathode were also used for comparison. The average removal rates of Cu(II) and Ni(II) were almost the same (0.39 and 0.40 mM hr(-1) (or 0.117 and 0.12 mmol hr(-1)), respectively) but higher than that of Fe(III) (0.16 mM hr(-1), or 0.048 mmol hr(-1)) in accordance with the Nernst-Planck flux equation. The removal rates for the same cation were independent of the cathode used. The average removal rate of each impurity was approximately proportional to the product of its initial concentration and separator area/anolyte volume ratio using Pb cathodes. Under constant current conditions the system using the Pt-C / Nafion cathode needed the highest cell voltage, about 3 V more than needed for the system with the Pt / Nafion cathode. The cell voltage required using the Pt / Nafion cathode was similar to that using the conventional planar Pb cathode. Analyses of cathode deposits by SEM/EDS and XPS techniques indicated they were minimal on the Pb and Pt / Nafion cathode and more apparent on the Pt-C / Nafion cathode. The primary deposits on the Pb cathode were chromium oxides (e.g., Cr2O3) with minor amount of lead chromate (lead dichromate or lead trichromate) and other chromium solids (Cr black). As expected, the dominant deposit on the lead anode surface was PbO2.

Carcinogens, Environmental↗