Cr Chloride Research Articles

Effects of Supplemental Chromium Source and Concentration on Growth, Carcass Characteristics, and Serum Lipid Parameters of Broilers Reared Under Normal Conditions.

An experiment was conducted to investigate the effects of dietary chromium (Cr) source and concentration on growth performance, carcass traits, and some serum lipid parameters of broilers under normal rearing conditions for 42days. A total of 252 1-day-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involved in a 2×3 factorial arrangement of treatments with three Cr sources (Cr propionate (CrPro), Cr picolinate (CrPic), Cr chloride (CrCl3)) and two concentrations of added Cr (0.4 and 2.0mg of Cr/kg) plus a Cr-unsupplemented control diet. The results showed that dietary Cr supplementation tended to increase the breast muscle percentage compared with the Cr-unsupplemented control group (P=0.0784), while Cr from CrPic tended to have higher breast muscle percentage compared with Cr from CrCl3 (P=0.0881). Chromium from CrPic also tended to increase the breast intramuscular fat (IMF) compared with Cr from CrCl3 (P=0.0648). In addition, supplementation of 0.4mg/kg Cr tended to decrease low-density lipoprotein cholesterol (LDL-C) (P=0.0614). Compared with the control group, broilers fed Cr-supplemented diets had higher triglyceride (TG) (P=0.0129) regardless of Cr source and Cr concentration. Chromium from CrPro and CrPic had lower total cholesterol (TC) compared with Cr from CrCl3 (P=0.0220). These results indicate that dietary supplementation of Cr has effects on carcass characteristics and serum lipid parameters of broilers under normal rearing conditions, while supplementation of organic Cr can improve carcass characteristics and reduce the cholesterol content in serum.

Effect of chromium supplementation on glycated hemoglobin and fasting plasma glucose in patients with diabetes mellitus.

AimsChromium (Cr) is a trace element involved in glucose homeostasis. We aim to evaluate and quantify the effects of Cr supplementation on A1C and FPG in patients with T2DM.Materials and methodsA systematic literature search of Pubmed, EMBASE and the Cochrane Library (from database inception to 11/2014) with no language restrictions sought RCTs or cohort studies evaluating Cr supplementation in T2DM vs control and reporting either change in glycated hemoglobin (A1C) or fasting plasma glucose (FPG). Meta-analysis was conducted on each subtype of Cr supplement separately, and was analyzed by random effects model to yield the weighted mean differences (WMD) and 95% confidence intervals (CIs). Heterogeneity was assessed by using the I2 statistic.ResultsA total of 14 RCTs (n = 875 participants, mean age range: 30 to 83 years old, 8 to 24 weeks of follow-up) were identified (Cr chloride: n = 3 study, Cr picolinate: n = 5 study, brewer’s yeast: n = 4 study and Cr yeast: n = 3 study). Compared with placebo, Cr yeast, brewer’s yeast and Cr picolinate did not show statistically significant effects on A1C. Furthermore, compared to control, Cr chloride, Cr yeast and Cr picolinate showed no effect on FPG, however, brewer’s yeast showed a statistically significant decrease in FPG -19.23 mg/dL (95% CI = -35.30 to -3.16, I2 = 21%, n = 137).ConclusionsCr supplementation with brewer’s yeast may provide marginal benefits in lowering FPG in patients with T2DM compared to placebo however it did not have any effect on A1C.

Synthesis and redox reactivity of a phosphine-ligated dichromium paddlewheel

A pentadentate ligand platform, bis[2-(diisopropylphosphino-methylamino)phenyl]ether (1), abbreviated as H2(PNONP), is introduced that enables the isolation of homodinuclear chromium complexes. In a one-step metalation using Cr(III) and Cr(II) chloride reagents, the bimetallic compounds, [Cr(μ-Cl)(PNONP)]2 (2) and [Cr(PNONP)]2 (3), respectively, were synthesized. These complexes have been characterized by X-ray diffraction, NMR spectroscopy, cyclic voltammetry, magnetometry, UV–Vis–NIR spectroscopy, combustion analysis, and computational methods. Complex 3 has a reasonably short Cr–Cr bond length of 2.1342(5)Å. Quantum chemical calculations support a diradical singlet ground-state with a formal triple bond between the chromium centers. By cyclic voltammetry, 3 exhibits two reversible oxidations at E½=−470 and −750mV versus FeCp20/+. The one- and two-electron oxidized analogues, 3+ and 32+, were generated in situ via chemical oxidation using ferrocenium. Based on in situ characterization of 3+ and 32+, we hypothesize the oxidations are metal-based to yield Cr25+ and Cr26+ cores, respectively.

Lack of Effect of Dietary Chromium Supplementation on Growth Performance and Serum Insulin, Glucose, and Lipoprotein Levels in Broilers Reared Under Heat Stress Condition

This study evaluated the effects of supplemental dietary chromium (Cr) on the performance, carcass traits, and some serum parameters of broilers under a heat stress (23.9 to 37°C cycling) condition. A total of 150 1-day-old broiler chicks (Cobb 500) according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Treatments were supplemented with 0 (control), 600, and 1,200μgkg(-1) Cr in the form of Cr chloride (CrCl3) and Cr L-methionine from 1 to 49days of age. Blood samples were collected from two birds in each replicate to determine serum parameters at 35 and 49days of age. The body mass, feed intake, and conversion ratio were not influenced by dietary Cr (P > 0.05). Dietary supplementation of Cr from either CrCl3 or Cr L-methionine caused increased serum concentrations of Cr (P < 0.05), but had no effect on serum insulin and glucose concentrations at both sampling times (P > 0.05). Serum triglycerides, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were also not significantly affected (P > 0.05) by dietary treatments, whereas total cholesterol concentration decreased in chicks fed Cr L-methionine compared to the control (P < 0.05).

Selective catalytic reduction of NO with NH3 over Cr-ZSM-5 catalysts: General characterization and catalysts screening

Cr exchanged ZSM-5 catalysts (Cr/Al=1) prepared by solid-state ion exchange were tested in SCR of NO with ammonia. Since CrCl3 precursor sublimates during the solid-state reaction, chromate species were stabilized in the exchange sites of H+-ZSM-5 (Si/Al=15) and Cr2O3 formation is, therefore, limited. However, using Cr nitrate and NH4+-ZSM-5 (Si/Al=26) zeolite, massive particles of α-Cr2O3 occupied the catalyst surface. At the contrary, well-dispersed particles of Cr2O3 were detected with H+-ZSM-5 and Cr nitrate precursor. Starting from Cr acetate precursor, agglomerates of amorphous oxide were detected with H+-ZSM-5 like support. In the temperature range 50–300°C, Cr chloride and Cr nitrate precursors and H+-ZSM-5 led to highly active catalysts, while Cr nitrate and NH4+-ZSM-5 led to a poorly active catalyst. However, catalysts issued from Cr acetate are promising in SCR but inefficient agglomerates of oxide (amorphous or crystalline chromia) could be avoided with NH4+-ZSM-5 like support.

Cr–ZSM-5 catalysts for ethylene ammoxidation: Effects of precursor nature and Cr/Al molar ratio on the physicochemical and catalytic properties

Cr–ZSM-5 catalysts prepared by solid-state ion exchange with different Cr/Al molar ratios were characterized and tested in ethylene ammoxidation to acetonitrile in the temperature range 425–500°C. Starting from Cr acetate like precursor and lower Cr load (Cr/Al=0.5), small amount of chromate species, sited inside the zeolite matrix, exhibited lower catalytic activity in ammoxidation (12.5% of CH3CN yield). Increasing the Cr amount (Cr/Al=1) does not significantly improve the catalytic properties since agglomerates of amorphous Cr2O3 inhibited the accessibility of chromate species to the reactants. However, at higher Cr amount (Cr/Al=1.5), crystalline Cr2O3 particles reduced the diffusion of reactants to the internal active sites. Starting from Cr chloride like precursor, the corresponding solids are low-exchanged since CrCl3 evaporates. At Cr/Al molar ratios of 0.5 and 1, chromate species, sited in the exchange sites, exhibited interesting catalytic properties (18.5 and 25% of CH3CN yield at 500°C, respectively). Nevertheless, at higher metal load (Cr/Al=1.5), the excess of Cr transforms into crystalline Cr2O3 which inhibits the diffusion of reactants to the active sites and enhances the hydrocarbon oxidation mainly at low temperatures. As ethylene ammoxidation required ammonia activation over (poly)chromate sites, a possible pathway of such a step has been proposed on the basis of NH3-TPD results.

Growth performance and starch utilization in common carp (Cyprinus carpio L.) in response to dietary chromium chloride supplementation

A nutrition trial was conducted on juvenile common carp (Cyprinus carpio), initial mean body weight 15±0.4g within a controlled facility at 25±0.5°C. Six diets containing various levels of supplementary Cr (0, 0.2, 0.5, 1.0, 1.5, and 2.0) mg Cr/kg of diet as Cr chloride hexahydrate were fed to carp for a period of 10weeks. Lower growth performance was observed in fish fed on the control diet and the diet supplemented with the highest level of Cr (2.0mg Cr/kg). Although fish fed 0.5mg Cr/kg showed the best growth performance, this was not significantly different (P>0.05) from fish fed 1.0mg Cr/kg. The regression of plasma glucose concentration was linear (R2=0.97 and P value=0.001) as the Cr content of the diet increased (up to 1.5mg Cr/kg).Cr carcass content was elevated with an increasing level of dietary Cr supplementation up to 1.5mg Cr/kg; but fish fed on the diet supplemented with the highest level of Cr (2.0mg Cr/kg) showed a decrease in Cr carcass content.Histological examination to evaluate the impact of different Cr supplementation on liver and gut tissues showed notable changes. The higher level of Cr (2.0mg Cr/kg) in the diet gave rise to elevated hepatocyte vacuolization and changes in gut tissue morphology.It appeared that Cr chloride significantly improved growth within a defined range (0.2–1.5) mg Cr/kg without any negative impact, while 2.0mg Cr/kg in carp diet seems to be the threshold for the initiation of toxicity.

The Efficacy of Chromium as a Growth Enhancer for Mirror Carp (Cyprinus carpio L): An Integrated Study Using Biochemical, Genetic, and Histological Responses

A growth trial was conducted on juvenile mirror carp (Cyprinus carpio L.) for 8 weeks to compare the efficacy of three chromium (Cr) compounds (Cr chloride, Cr picolinate, and Cr yeast) at a level 0.5 mg/kg as a potential growth enhancer. In addition, a high level of Cr (2.0 mg/kg) as Cr chloride has also been added in parallel for comparison. All Cr fortified diets at a level 0.5 mg/kg produced superior growth for carp compared to the control group and the group fed the high level of Cr chloride (2.0 mg/kg). Metabolic indicators measured included two of the key liver enzymes (hexokinase, HK) and (glucose-6-phosphate dehydrogenase, G6PD) activity. The results validated the positive effect of Cr at a level 0.5 mg/kg on enzyme activity and carbohydrate utilization producing significantly better growth performance for mirror carp. The study also included measurement of DNA strand breaks in the erythrocytes using the comet assay which revealed significantly (P < 0.05) increased DNA damage in fish fed on high level of Cr chloride (2.0 mg/kg) but the other treatments were not significantly different (P > 0.05) from the control groups. The concentration of Cr in the liver, gut, and whole fish tissues increased with increasing dietary Cr supplementation. Overall, Cr supplementation at a level 0.5 mg/kg from different sources may affect growth performance in carp by activation of some key liver enzymes (HK and G6PD).

Chromium Supplementation Can Alleviate the Negative Effects of Heat Stress on Growth Performance, Carcass Traits, and Meat Lipid Oxidation of Broiler Chicks without Any Adverse Impacts on Blood Constituents

This study was conducted to determine the effects of dietary supplementation with Cr nicotinate and Cr chloride and their optimum inclusion rate on performance, carcass traits, meat oxidative stability, serum metabolites, hematological parameters, and liver chromium concentration in heat-stressed broilers. A total number of 420, 1-day-old male broiler chicks were randomly assigned to seven treatments with four replicates of 15 chicks. The dietary treatments consisted of the basal diet supplemented with 0 (control), 500, 1,000, and 1,500 μg/kg Cr in the form of Cr nicotinate and Cr chloride. Chicks were raised for 6 weeks in heat stress condition (33 ± 2°C). Supplements of organic and inorganic Cr particularly at 1,500 μg/kg incorporation increased feed consumption (P < 0.05) and body mass gain of broilers (P < 0.01). Cr supplementation increased carcass yield and decreased abdominal fat (P < 0.01). Supplementation of 1,500 μg/kg Cr nicotinate (P < 0.05) enhanced liver Cr concentration. Storage time increased lipid oxidation of meat (P < 0.01). Cr decreased lipid oxidation of breast and thigh muscles over 2 (P < 0.01) or 6 (P < 0.05) days of storage time. Birds fed 1,500 μg/kg Cr nicotinate, had lower concentration of serum glucose and triglyceride at 21 days (P < 0.05). Hematological parameters tested at 21 and 42 days, were not influenced. The results suggested that dietary Cr supplementation regardless of its source have a positive effect on productive, and carcass traits, also enhances oxidative stability of refrigerated meat in broilers reared under heat stress conditions.

Ethylene Oligomerization Promoted by a Silylated-SNS Chromium System

The ethylene trimerization SNS ligand has been modified by replacing the methylene carbons flanking the nitrogen atom with dimethyl silyl groups. Three ligands, CySCH2Si(CH3)2N(H)Si(CH3)2CH2SCy (a), (t-Bu)SCH2Si(CH3)2N(H)Si(CH3)2CH2S(t-Bu) (b), and PhSCH2Si(CH3)2N(H)Si(CH3)2CH2SPh (c), have been prepared. Ligand a in either protonated or deprotonated forms was reacted with CrCl3(THF)3 to afford the corresponding monomeric [CySCH2Si(CH3)2N(H)Si(CH3)2CH2SCy]CrCl3 (1a) or dimeric {[CySCH2Si(CH3)2NSi(CH3)2CH2SCy]CrCl(μ-Cl)}2 (2a). One-pot reaction of a in the presence of Et2AlCl with either Cr(III) or Cr(II) chlorides afforded in either case the divalent {[CySCH2Si(CH3)2N(H)Si(CH3)2CH2SCy]Cr{(μ-Cl)Al(CH2CH3)2Cl}2 (3a). To deprotonate the N–H function of the Si-SNS ligand, n-BuLi was used for the purpose of preparing the divalent chromium analogue. The reaction afforded in the case of both a and b the two nearly isostructural divalent complexes {[CySCH2Si(CH3)2NSi(CH3)2CH2SCy]Cr(μ-Cl)}2 (4a) and {[(t-Bu)SCH2Si...

Tissue accumulation and urinary excretion of chromium in rats fed diets containing graded levels of chromium chloride or chromium picolinate

To attempt a risk assessment of the excess intake of trivalent chromium (Cr), tissue Cr accumulation and urinary Cr excretion were examined in weanling rats fed experimental diets containing graded levels of Cr chloride (CrCl3) or Cr picolinate (CrPic). Thirty-six male weanling 4-weeks-old Wistar rats were divided into six groups and fed a casein-based semi-purified diet (Cr content: <0.02 microg/g) supplemented with 1, 10, or 100 microg Cr/g as CrCl3 or CrPic for 28 days. Among the experimental groups, no significant difference was observed in body weight; however, supplementation of 100 microg Cr/g to the diets caused a significant low liver weight irrespective of the chemical species of Cr. Activities of serum aspartate aminotransferase and alanine aminotransferase were significantly elevated in rats given CrPic at 100 microg Cr/g. In the liver, kidney and femur, Cr accumulation increased with elevation of the dietary Cr level. No influence of the difference in the chemical species of supplemented Cr was observed in the liver and kidney, but CrCl3 caused significantly higher Cr accumulation than CrPic in the femur of rats given 100 microg Cr/g. Daily urinary Cr excretion elevated with the increase of the dietary Cr level. Rats given CrPic showed significantly higher daily urinary Cr excretion than those given CrCl3, particularly at a dietary Cr level of 100 microg/g. The rate of urinary Cr excretion in rats given CrPic was constant, irrespective of the dietary Cr level, but that of rats given CrCl3 fell with the increase of the dietary Cr level. These results indicate that the lowest adverse effect level of dietary Cr is less than 100 microg/g, irrespective of the chemical species of Cr.

Reactivity Consequences of Steric Reduction in Cyclopentadienyl Chromium β-Diketiminate Complexes

A series of Cr(III) half-sandwich β-diketiminate complexes, CpCr[(ArNCMe)2CH]X, X = I (2), CH3 (3), or Cl (4), were prepared. Compared to previously communicated complexes with Ar = 2,6-iPr2C6H3 (Dpp, a), Cr(III) complexes with less sterically demanding ligands such as Ar = 2,6-Me2C6H3 (Xyl, b), 2,4,6-Me3C6H2 (Mes, c), or 2,6-Et2C6H3 (Dep, d) were more readily synthesized via salt metathesis reactions. Iodide compounds 2b−d were prepared by oxidation of the corresponding Cr(II) species CpCr[(ArNCMe)2CH] 1b−d with half an equivalent of iodine. The Cr(III) chloride complexes CpCr[(ArNCMe)2CH]Cl 4c−d were prepared in a two-step, one-pot reaction from anhydrous CrCl3. The reaction of MeMgI with either the Cr(III) chloride or iodide precursors yielded the Cr(III) methyl complexes CpCr[(ArNCMe)2CH](CH3) 4b−d. All of the paramagnetic Cr(III) complexes were characterized by UV−visible spectroscopy and elemental analysis, and the structures of 2b, 2c, 3b, 3c, 3d, 4c, and 4d were determined by X-ray crystallography...

Efficacy of trivalent chromium on growth performance, carcass characteristics and tissue chromium in heat‐stressed broiler chicks

AbstractBACKGROUND: Trivalent chromium (Cr) is usually claimed to have a positive effect on growth and carcass traits in livestock. The objective of this study was to comparatively assess the effects of 6 weeks of treatment with different forms of Cr (500 µg kg−1), namely Cr nanocomposite (CrNano), Cr picolinate (CrPic) and Cr chloride (CrCl3), on growth performance, carcass characteristics and tissue Cr in heat‐stressed broiler chicks.RESULTS: Supplementation of CrNano and CrPic significantly increased average daily gain, feed efficiency, carcass yields and lean muscles and decreased abdominal fat. In addition, CrNano significantly increased protein contents in breast and thigh muscles and lowered fat and cholesterol levels in thigh muscles. CrPic significantly increased thigh muscle protein content and decreased thigh muscle fat and cholesterol levels. Dietary addition of CrNano, CrPic and CrCl3 resulted in significant increases of Cr content in serum, liver and kidney. Moreover, supplemental CrNano produced significant increments of Cr deposit in breast and thigh muscles.CONCLUSION: The results indicate that supplementation of Cr in the form of CrNano and CrPic might be an effective tool for enhancing the growth performance and carcass traits of broiler chicks in heat‐stressed condition. CrNano seemed to have greater beneficial effects in comparison with CrPic. Copyright © 2009 Society of Chemical Industry

Effect of Organic and Inorganic Chromium Supplementation on Meat Quality of Heat-Stressed Broiler Chicks

This study examined the effect of different levels of dietary organic and inorganic chromium (Cr) on meat quality of broiler chicks reared under heat stress condition. Four hundred and twenty Ross male chickens in heat stress condition (33±3°C) were allocated to seven treatments in a completely randomized design. Treatments were supplemented with 0 (control), 500, 1000 or 1500 µg kg −1 Cr in the form of Cr nicotinate and Cr chloride. Twelve chicks from each treatment were slaughtered at 42 d, to evaluate moisture, protein, lipid, pH and lipid oxidation of thigh and breast meat. Moisture, lipid and pH of meat were not affected by supplemental Cr. Breast meat protein was significantly (p<0.05) increased by the Cr supplementation especially organic Cr. Storage time increased lipid oxidation of meat (p<0.01). Lipid oxidation of breast and thigh muscle for two days of storage were affected by supplemental Cr and decreased (p<0.05). Results of the present study showed that supplementation of diet with Cr can improve the meat quality of broiler chicks in heat stress condition.

Safety of trivalent chromium complexes: No evidence for DNA damage in human HaCaT keratinocytes

Several studies have demonstrated beneficial effects of supplemental trivalent Cr in subjects with reduced insulin sensitivity with no documented signs of toxicity. However, recent studies have questioned the safety of supplemental trivalent Cr complexes. The objective of this study was to evaluate the cytotoxic and genotoxic potential of the Cr(III) complexes (histidinate, picolinate, and chloride) used as nutrient supplements compared with Cr(VI) dichromate. The cytotoxic and genotoxic effects of the Cr complexes were assessed in human HaCaT keratinocytes. The concentrations of Cr required to decrease cell viability were assessed by determining the ability of a keratinocyte cell line (HaCaT) to reduce tetrazolium dye, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. DNA damage using the Comet assay and the production of 8-hydroxy-2′-deoxyguanosine were also determined with and without hydrogen peroxide-induced stress. The LC50 for human cultured HaCaT keratinocytes was 50 μM for hexavalent sodium dichromate and more than 120-fold higher for Cr chloride (6 mM) and Cr histidinate (10 mM). For Cr picolinate at saturating concentration (120 μM) the LC50 was not attained. High Cr(III) concentrations, 250 μM Cr as Cr chloride and Cr histidinate and 120 μM Cr picolinate (highest amount soluble in the system), not only did not result in oxidative DNA damage but exhibited protective antioxidant effects when cells were exposed to hydrogen peroxide-induced oxidative stress. These data further support the low toxicity of trivalent Cr complexes used in nutrient supplements.

Comparison of acute absorption of commercially available chromium supplements

Chromium (Cr) supplements are available as picolinate, nicotinate or chloride (the latter primarily in multivitamin–mineral supplements). The picolinate form has been reported to be the best absorbed and most efficacious, but some reports question which form has superior absorption. The present study examined acute Cr absorption, based on 24 h urinary Cr values, for picolinate, two types of nicotinate, and chloride in young adult, non-overweight females. College-aged women were given 200 μg of Cr as each of the four supplement types in random order accompanied by a small standardized meal, separated by at least a week washout. Cr picolinate produced significantly higher 24 h urinary Cr than either of two nicotinate supplements or Cr chloride given in a multivitamin–mineral supplement. This difference was seen for absolute values of the urinary Cr and for percent increases. In conclusion, based on an indirect measure of acute absorption, Cr picolinate was superior to three other Cr complexes commonly sold as supplements.

Glucose tolerance and serum concentrations of hormones and metabolites in goats (Capra hircus) fed diets supplemented with inorganic and organic chromium salts

Adult goats (no. = 18) were supplemented with chromium (Cr, 0.5 mg/kg concentrate) for 120 days as Cr chloride and Cr yeast complex and their responses in terms of glucose tolerance and serum profiles of metabolites and hormones were measured. The goats were fed 200 g/day of the concentrate and reared under a semi-intensive regimen. Cr supplementation significantly reduced serum glucose ( P = 0.049) and cholesterol ( P = 0.0001) levels compared with the same in the control group (calculated as % change between days 0 and 120). Serum cortisol on day 120 was lower in goats fed Cr chloride than in the control group ( P < 0.05). Overall, the mean cortisol level was lower ( P = 0.001) in the goats receiving added dietary Cr. An intravenous glucose tolerance test (IVGTT) was performed on the goats on day 75. The clearance rate (k) of glucose between 5 and 60 min of glucose infusion was significantly higher ( P = 0.004) in the goats supplemented with Cr yeast compared with those on the control or the Cr chloride supplemented diets. The kinetic parameters as well as the k and T1/2 responses for serum insulin during the IVGTT were not affected. The ratio between the insulin k to glucose k increased ( P = 0.011) in the goats fed added dietary Cr as Cr chloride compared with the control and the Cr yeast groups. Post-prandial serum levels of glucose (diet effect P = 0.038) and cholesterol (diet effect P = 0.033) was lower in both the Cr supplemented groups than the control. Serum glucose during an epinephrine challenge test tended to remain elevated ( P = 0.076) 2 h after epinephrine infusion in the Cr yeast group indicating a delayed return of serum glucose to the basal level. However, serum insulin and cortisol remained unaffected. Several changes in selected blood metabolites and hormone measurements were observed when Cr was added as a dietary supplement in the diet of the goats. Contrary to the generally accepted view, supplemental Cr may influence the metabolism of ruminants even in a non-stressed management regime.

Effects of Different Forms of Chromium Supplements on Serum Glucose, Insulin and Lipids in Rats

This study evaluated the effects of different forms of chromium supplements on serum glucose, insulin and lipid concentrations in rats. Sprague-Dawley male rats were randomly assigned to one of three dietary groups and fed AIN-76 semi-purified basal diets supplemented with 300 ppb Cr from Cr methionine (CrMet) and Cr chloride (CrCl₃) or without Cr (control). By the end of the 4^(th) week, all rats were decapitated, blood collected, and serum glucose, insulin and lipid concentrations were determined. The CrMet and CrCl₃ supplementation did not affect weight gain and feed efficiency ratio. However, feed intake was significantly higher in CrMet groups than control (p＜0.05). CrMet-supplemented rats had markedly increased insulin levels (p＜0.05) compared with controls. Serum lipids were not significantly different between the control and the CrMet groups. CrCl₃ supplementation decreased total cholesterol and triglyceride, but the decreases were only significant for the control group. CrCl₃ supplementation was associated with significant decreases in total cholesterol compared with CrMet supplementation. These results indicate that CrMet supplementation is effective for increasing serum insulin, and CrCl₃ may improve lipid concentrations, because we observed decreased serum total cholesterol and an improved total cholesterol/HDL-cholesterol ratio (THR).

Epigenetic and gene expression changes related to transgenerational carcinogenesis.

Transgenerational carcinogenesis refers to transmission of cancer risk to the untreated progeny of parents exposed to carcinogens before mating. Accumulated evidence suggests that the mechanism of this process is epigenetic, and might involve hormonal and gene expression changes in offspring. To begin to test this hypothesis, we utilized a mouse model (NIH Swiss) in which exposure of fathers to Cr(III) chloride 2 wk before mating can alter incidence of neoplastic and nonneoplastic changes in offspring tissues. Utilizing a MS-RDA approach, we found that the sperm of these fathers had a significantly higher percentage of undermethylated copies of the 45S ribosomal RNA gene (rRNA); this finding was confirmed by bisulfite sequencing. Because gene methylation is a known mechanism of expression control in germ cells, and ribosomal RNA levels have been linked to cancer, these findings are consistent with the hypothesis. Secondly, we observed that offspring of Cr(III)-treated fathers were significantly heavier than controls, and had higher levels of serum T3. Possible effects of T3 levels on gene expression in the offspring were examined by microarray analysis of cDNAs from liver. A total of 58 genes, including 25 named genes, had expression ratios that correlated significantly with serum T3 ratios at P </= 0.001. Some of these genes have potential roles in growth and/or tumor suppression. These results also support the hypothesis of an epigenetic and/or gene expression-based mechanism for transgenerational carcinogenesis. Published 2004 Wiley-Liss, Inc.

Formation, Characterization and Electrical Conductivity of Polycarbosilazane-Cu(II), -Ni(II) and -Cr(III) Chloride Metallopolymers

A series of transition metal-polycarbosilazane complexes have been prepared by the reaction of poly(N,N′-bis(dimethylsilyl)ethylenediamine), [–Si(CH3)2NHCH2CH2NH–] n , with Cu(II), Ni(II), and Cr(III) chloride. The resulting complexes were characterized by infrared (FT-IR) and UV-visible spectroscopy, magnetic susceptibility measurements, thermogravimetric analysis (TGA), and powder X-ray diffraction (XRD). The average chain-chain spacing in these materials were estimated from XRD data and found to be 6.88, 7.91, 7.09, and 6.33 A in metal-free, Cu(II)-, Ni(II)-, and Cr(III)-containing polycarbosilazanes, respectively. DC electrical conductivity measurements showed that all these metal-polycarbosilazane complexes exhibit semiconductor behavior while the metal-free matrix is an insulator.