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The effect of combined treatment with niacin and chromium (III) chloride on the different tissues of hyperlipemic rats.

We investigated the effects of a combined treatment with chromium (Cr) and niacin on the spleen, tongue, and lens tissues in terms of lipid peroxidation (LPO), glutathione (GSH), serum catalase (CAT), lactate dehydrogenase (LDH), serum cholesterol, and total lipid levels in normal and hyperlipemic rats. In this study, female 1-year-old Swiss albino rats were used. The rats were randomly divided into four groups. Group I rats (control) were fed with standard pellet chow. Group II rats were fed a lipogenic diet in which 2% cholesterol, 0.5% cholic acid, and 20% sunflower oil were added and were given 3% alcoholic water for 60 days. Group III rats were fed with the same lipogenic diet and were treated with a dose of 250 microg/kg body weight CrCI3 x 6H2O and 100 mg/kg body weight niacin, for 45 days, by gavage. The rats in group IV were fed with pellet chow and treated with 250 microg/kg body weight CrCI3 x 6H2O and 100 mg/kg body weight niacin, by gavage, for 45 days. After 2 weeks, the animals showed symptoms of hyperlipemia. On the 60th day, tissue and blood samples were taken. We have observed decreased CAT activity and GSH levels, increased LDH activity, cholesterol, total lipid, and LPO levels in hyperlipemic rats. Niacin and Cr administration to hyperlipemic rats increased tissue GSH levels and CAT activity and decreased tissue LPO levels and LDH activity, cholesterol, and total lipid levels compared with hyperlipemic rats. We conclude that the administration of a combination of niacin and chromium has a protective effect against oxidative damage to tongue, lens, and spleen tissues as a result of hyperlipemia.

Animals↗

Lack of toxicity of chromium chloride and chromium picolinate in rats.

OBJECTIVE: To evaluate the safety of chromium (Cr) as a nutrient supplement. Several recent studies have reported beneficial effects of supplemental Cr at levels higher than the upper limit of the suggested intake for Cr. Trivalent Cr is considered relatively nontoxic but some recent unconfirmed studies have questioned its toxicity. We evaluated the toxicity of Cr chloride and a more bioavailable form of trivalent Cr, Cr tripicolinate. METHODS: Harlan Sprague Dawley rats (4 weeks of age) were fed a stock diet to which was added 0, 5, 25, 50 or 100 mg of Cr per kg of diet as chloride or picolinate. Fasting blood samples were taken at 11 and 17 weeks and animals sacrificed at 24 weeks of age. Lack of toxicity was demonstrated by blood and histological measurements. Chromium incorporation into tissues was determined by graphite furnace atomic absorption. RESULTS: There were no statistically significant differences in body weight, organ weights or blood variables among all the groups tested at 11, 17 and 24 weeks. Blood variables measured were glucose, cholesterol, triglycerides, blood urea nitrogen, lactic acid dehydrogenase, transaminases, total protein and creatinine. Histological evaluation of the liver and kidney of control and animals fed 100 mg/kg Cr as Cr chloride or picolinate also did not show any detectable differences. Liver and kidney Cr concentrations increased linearly for both the Cr chloride and picolinate fed animals. CONCLUSIONS: These data demonstrate a lack of toxicity of trivalent Cr, at levels that are on a per kg basis, several thousand times the upper limit of the estimated safe and adequate daily dietary intake for humans. Animals consuming the picolinate supplemented diets had several-fold higher Cr concentrations in both the liver and kidney than those fed Cr chloride.

Animals↗

Structural modification and aggregation of mucin by chromium(III) complexes.

Metal ions binding to proteins regulate the functions of proteins and may also lead to structural changes. In this communication we demonstrate the interaction and subsequent conformational changes induced in pig gastric mucin (PGM) upon binding to certain chromium(III) complexes like, [Cr(salen)(H(2)O)(2)](ClO(4)) (1), [Cr(en)(3)]Cl(3) (2) and [Cr(EDTA)(H(2)O)]Na (3) which vary in charge and ionic character. Complexes 1 and 3 have been shown to interact coordinately with PGM whereas complex 2 binds through electrostatic interaction and hydrogen bonding. Steady state fluorescence experiment reveals that at lower concentration of complex 2 there is partial quenching of the tyrosine emission, whereas at higher concentration of the complex the emission intensity is enhanced. On the other hand with complexes 1 and 3 a decrease in fluorescence intensity was observed. PGM viscosity was found to decrease in the presence of complex 1 and 3 due to the formation of flexible fibres through coordinate interaction. Complex 2 was found to facilitate metal induced intertangling of PGM fibres which tends to stabilize the interaction and leads to sol-gel transition with subsequent increase in viscosity. A significant change in CD spectrum of PGM was observed in the presence of complex 2, where random coil spectrum became typical of a alpha-helical structure with 80% alpha helix content. In the case of complexes 1 and 3 only minor changes in the amplitude of the spectrum were observed. Histochemical analysis supports the contention that complex 2 favors the oligomerisation of PGM and leads to the formation of aggregated mass of macromolecules.

Animals↗

Aggregation of mucin by chromium(III) complexes as revealed by electrokinetic and rheological studies: influence on the tryptic and O-glycanase digestion of mucin.

In the present study, the impact of chromium(III) complexes ([Cr(salen)(H2O)2](+) (1), [Cr(en)3]3+ (2) and [Cr(EDTA)(H2O)]- (3)) on the biophysical properties of mucin like specific viscosity, zeta potential and particle size has been investigated. It is evident from the present investigation that the nature of the coordinated ligand has a major role to play in bringing about the changes in the physical characteristics of the glycoprotein. It was observed that (1) and (3) because of their coordinate mode of binding lead to decrease in the specific viscosity of mucin, whereas (2) on the other hand was found to bring about drastic increase in the mucin viscosity due to sol-gel transition in the mucin conformation. Complex (2) was found to gradually lower the zeta potential value of mucin (particle size=51.5 nm) from -24.8 +/- 1.31 mV to -0.58 +/- 0.30 mV, which reveals aggregation (particle size=216 nm) and subsequent sedimentation of mucin with an increase in the average diameter of mucin particles. The binding of (2) to mucin was found to impart resistance to mucin against both tryptic and O-glycanase digestion, suggesting that, the aggregation of mucin causes conformational as well as configurational changes in the glycoprotein; thus perturbing the location of carbohydrate domains.

Animals↗

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↗

Ion exchange sorption of Pb2+ ions on CrPO4.

The chromium(III) phosphate was observed to have a high affinity towards Pb2+ ion and the sorption capacities were found to be in the order: Pb2+ > Cu2+ > Cd2+ > Ni2+. Different characterization methods i.e. FTIR, SEM and EDX were employed to investigate the sorption mechanism of Pb2+ by chromium(III) phosphate, which showed that no new solid phases were present in the residue after sorption of Pb2+. The exchange between protons from the surface and Pb2+ from solutions was found to be responsible for Pb2+ sorption by chromium (III) phosphate.

Adsorption↗

Uptake of molybdate by adsorption onto industrial solid waste Fe(III)/Cr(III) hydroxide: kinetic and equilibrium studies.

Removal of molybdate on to industrial solid waste Fe(III)/Cr(III) hydroxide as adsorbent has been investigated. Pretreated adsorbent was found to be more efficient in the uptake of molybdate compared to untreated adsorbent. Effect of pH on the adsorption was studied in the pH range 4.0 to 10.0. Optimum pH for maximum removal was found to be 4.0. Langmuir and Freundlich isotherm models were used to study the adsorption capacity of the adsorbent. The adsorption follows second order kinetics. No significant effect of temperature has been observed. Desorption studies showed that ion exchange mechanism is predominant.

Adsorption↗

Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects.

Chromium in the hexavalent form, Cr(VI), has long been recognized as a carcinogen and there is concern as to the effects of continuous low-level exposure to chromium both occupationally and environmentally. This review summarizes the available exposure data and known health effects and evaluates the potential risk to human health in the United Kingdom. Chromium emissions to the environment in the United Kingdom are predominantly derived from fuel combustion, waste incineration, and industrial processes. The less toxic trivalent form of chromium [Cr(III)] is dominant in most environmental compartments, and any Cr(VI), the more toxic form, that is emitted to the environment can be reduced to Cr(III). Food is a major source of exposure to chromium, and estimated daily oral intakes for infants (1 yr), children (11 yr), and adults are 33-45, 123-171, and 246-343 micrograms/person/d, respectively. Soil ingestion, particularly common in young children, can contribute to oral intake. Inhalation is a minor route of exposure for the general population. Average daily inhalation intakes in infants can range from 0.004 microgram/d for rural infants to 0.14 microgram/d for urban infants who are passively exposed to tobacco smoke, whereas adults who live in industrialized areas and smoke may take up between 2 and 12 micrograms/d. The most serious health effect associated with Cr(VI) is lung cancer, which has been associated with some occupational exposure scenarios, whereas Cr(III) is an essential nutrient with a broad safety range and low toxicity. The human body has effective detoxification mechanisms that can reduce ingested or inhaled Cr(VI) to Cr(III). In conclusion, there is no clear evidence to relate exposure to environmental levels of chromium with adverse health effects in either the general UK population or subgroups exposed to chromium around industrialized or contaminated sites. It can be expected that an improved understanding of the relevance of possible long-term accumulation of Cr(III) in the body may facilitate a more complete assessment, in the future, of the health risks in the general population associated with environmental exposure to chromium.

Animals↗

Derivation and study of human epithelial cell lines resistant to killing by chromium trioxide.

CrO3 is cytotoxic for human epithelial 293 kidney cells over a narrow concentration range of approximately 2-8 microM (D50 approximately 3.0 microM); significantly greater toxicity is observed in clonogenic assays (D50 approximately 0.1-1.0 microM). Survival of a small fraction of cells (< or = 0.1%) at CrO3 concentrations between 10(-5) to 10(-3) M, and first-order kinetics of cytotoxicity, rationalized the derivation of a new panel of transformed human epithelial cell lines resistant to cytotoxic concentrations of CrO3 over the range of 5-100 microM. Wild-type and Cr-resistant 293 cell lines display similar morphology under phase microscopy, but wild-type cells grow faster and reach stationary phase sooner than Cr-resistant cells. The Cr-resistant phenotype is stable, and it is specific, since Cr-resistant cells are killed by NiSO4 or by CdCl2 at concentrations equivalent to those that kill wild-type cells. Toxicity analysis curves subjected to target theory suggest that the Cr-resistant cell lines have fewer Cr-sensitive "targets" and have undergone a "loss of function" compared to wild-type cells. This loss of function may be related to significantly lower rates of uptake of Na2(51)CrO4,which correlate inversely with CrO3 concentrations used for the selection and maintenance of the Cr-resistant lines, and to reduced levels of an approximately 96-kDa protein in comparison to wild-type cells. This new panel of Cr-resistant transformed human epithelial kidney cell lines will be useful in comparative studies of genetic resistance and sensitivity to human Cr(VI) toxicity, sulfate transport, and growth control differences between wild-type and Cr-resistant cells.

Apoptosis↗

Pathogenesis of nitrogen dioxide-induced respiratory lesions in reference to respiratory clearance of inhaled particulates.

The pathogenesis of NO2-induced respiratory disease and the effect of NO2 on respiratory clearance of 51Cr2O3 were studied. Young adult female mice were exposed to a 51Cr2O3 aerosol, followed by a daily exposure to either 30 ppm NO2 for 2 wk or 60 ppm NO2 for 2 wk or a single exposure to 170 ppm NO2. Exposure to 30 ppm NO2 had a minimal histopathologic effect on respiratory tract tissue. Exposure to 60 ppm NO2 produced marked histopathologic effects, which were subsequently resolved. Exposure to 170 ppm NO2 produced permanent histopathologic lesions. In mice exposed to concentrations of NO2 that produced minimal histopathologic effects, respiratory clearance of 51Cr2O3 was similar to that in unexposed mice. When mice were exposed to concentrations of NO2 that produced permanent tissue damage, prolonged impairment of respiratory clearance of 51Cr2O3 was observed, despite resolution of edema produced by inhalation of NO2. At concentrations of NO2 that produced marked edema and histopathologic effects that were resolved despite repeated NO2 exposure, there was an initial marked impairment of respiratory clearance, then an accelerated rate of clearance, and finally a clearance rate similar to that of unexposed mice. The time during which accelerated clearance occurred was well correlated with the time at which the histopathologic lesions was observed to regress.

Animals↗

Speciation of hexavalent chromium in welding fumes interference by air oxidation of chromium.

The determination of various chromium species in welding fume normally involves digestion in a hot alkaline solution. This work confirms that Cr(III) can be oxidized to Cr(VI) during this digestion. However, only dissolved forms of Cr(III), such as the hydroxochromate(III) ion, [Cr(OH)4], are susceptible to oxidation under these conditions. The air oxidation of Cr(III) can be prevented by hydrolytic destabilization of the hydroxochromate(III) complex by the presence of magnesium hydroxide precipitate. The procedure has been used successfully in the determination of insoluble chromium(VI) in welding fumes. Excellent reproducibility is documented for soluble and insoluble chromium(VI) fractions in the analysis of a bulk sample of welding fume.

Air Pollutants, Occupational↗

Reverse passive hemagglutination tests for rapid diagnosis of snake envenomation.

Reverse passive hemagglutination (RPHA) tests for the detection of six major poisonous snake venoms of Thailand were studied. Three different species of red blood cells i.e., sheep (SRBC), human (HRBC) and chicken (CRBC) were sensitized with protein A-affinity purified rabbit antivenom IgG using chromic chloride as a coupling reagent. The properties of these sensitized erythrocytes with regard to sensitivity, specificity, stability to venom enzymes and storage etc., were studied and compared. The sensitivities of the RPHA tests in venom detection were 2 to 635 ng/ml. Cross-reactions were observed with heterologous venoms at concentrations at least 62 times higher than those observed with homologous venoms. After treatment with glutaraldehyde, the coupled red blood cells showed reduced sensitivity but were stable at 4 degrees C from 1 to 12 months depending upon the antibody and the species of erythrocytes. The entire test required 60 to 120 min. The RPHA using fresh SRBC correctly identified various venoms in 48 of 59 (81.3%) serum samples and 16 of 26 (61.5%) wound swabs. Venom mis-identifications were made in 2 sera (3.4%). In a comparison of 24 paired serum and wound swab samples, more positive identifications were made with serum than with swab samples but the difference was not statistically significant (p > 0.05).

Animals↗

[Measurement of ileal protein digestibility using 15N-labeled rats].

After 15N-labelling over 7 days male albino rats (92-95 g live weight) received either a wheat or whole egg diet (10 animals each) for 4 days. On the following day of the experiment 5 animals each continued to receive their diets as their morning meal (group 1 whole egg, group 3 wheat) and 5 animals each after the previous feeding of a wheat diet received a 2.9 g whole egg diet (group 2) and after the previous feeding of a whole egg diet a 2.85 g wheat diet (group 4) resp. This morning meal was supplemented with chromium(III)oxide. The rats consumed their meals within 20 minutes. The animals were killed 3.5 hours after the beginning of feed intake. At that time the following relative amounts (in % of the intake) could be detected in the stomach in the sequence of groups 1 to 4: Cr2O3 = 22.5; 26.5; 57.5 and 64.2; dry matter = 25.4; 22.1; 43.2 and 38.5. The better agreement between the whole egg diet and Cr2O3 can be explained with the hydrophobic qualities of Cr2O3 and the small disposition of the Cr2O3 to decompose in combination with the whole egg diet. In the first third of the small intestines less than 1% of the intake of Cr2O3 and a maximum of 3.5% of the DM could be detected. Between 20 and 36% of the Cr2O3 and between 15 and 20% of the dry matter intake were ascertained in the small intestines as a whole; in the large intestines the values were 12-20% of the Cr2O3 and 16-23% of the DM. Endogenous 15N-secretion could be ascertained in all parts of the digestive tract. According to the method suggested by U. Bergner and H. Bergner (1982), protein digestibility in the last third of the small intestines was calculated as follows: (formula; see text) The following ileal digestibility values were calculated for crude protein: whole egg = 95.6%; whole egg (wheat previously) = 95.5%; wheat = 94.1%; wheat (whole egg previously) = 85.1%. It is a precondition for the application of this method that at the time of killing representative quotas of the diet sample to be tested can be detected both in the stomach and the large intestine so that the decrease of 15N-labelling in the ileum is actually caused by the test protein.

Animals↗

[Influence of the physical properties of straw pellets on their digestibility and passage rate of Cr2O3 in sheep].

By means of pelleting them one to four times (press G 600) and adding 20% sugar beet chips and 3% ammonia hydrogen carbonate at varying loose density (357-561 kg/m3) 4 straw pellet charges were produced. Significant differences could be ascertained for these pellets with regard to the fineness coefficient (I-IV 1.67; 1.30; 1.19; 0.83), hardness of pellets (5.4; 8.8; 9.4; 18.6 N/m2/10(5) and partly the loose volume. After testing four wethers per group, an energy concentration in the same sequence was ascertained as follows: 409, 388, 377 and 382 EFUcattle/kg dry matter. Apart from a higher crude fibre digestibility of groups I and II compared to III there were no significant differences in the digestibility. The measuring of feed passage time with the help of Cr2O3 did not result in directed differences. On an average of all groups, 80% of the Cr2O3 excretion was achieved after 70.5 +/- 0.7 h. The mean retention time of Cr2O3 in the digestive tract in all four groups was in average 53.3 +/- 1.2 hours. The different fineness degrees and values of the hardness of straw pellets remained without significant effects on the feed value of the straw pellets in the experiments with sheep.

Animal Feed↗

[Determination of the passage of two markers in the gastrointestinal tract of steers using different evaluation methods: effect of the level of nutrition].

This study was conducted to investigate the effects of amount of intake of a mixed diet by steers on the passage of digesta through the reticulorumen and the whole digestive tract. Six ruminally cannulated steers received a mixed diet consisting on average of 43% grass silage, 25% maize silage, 30% concentrate and 2% mineral-vitamin mix in DM. The experimental design was a repeated 3 x 3 Latin square with 21 days periods. The diet was offered twice daily (07.00 and 19.00 h) at 1, 1.5 and 2 times of estimated maintenance energy requirements. At the beginning of each period, animals received pulse doses of Titanium(IV)-oxide (TiO2) per os and Cr-EDTA intraruminally. Following marker administration, faecal marker concentrations were determined over 120 h. Passage parameters were estimated by a mono-exponential and a bi-exponential model, by models including gamma age-dependency and by a model calculating total tract mean retention time as mean value of all points on the marker-excretion curve. Passage rate of TiO2 from the reticulorumen increased with higher intakes, whereas mean retention time in the whole tract decreased. In general, results of different models were consistent across intakes. Values for passage of TiO2 were in good agreement with those reported for small particles, when similar diets were fed to cattle. Rate of passage of Cr-EDTA from the reticulorumen increased with higher intakes, and mean retention times of Cr-EDTA in the reticulorumen and in the whole tract decreased. Differences between models with or without age dependency were greater for Cr-EDTA than for TiO2. Fit to Cr-EDTA excretion curves was not satisfactory for models with gamma age dependency. Irrespective of model and marker, passage from the reticulorumen accelerated markedly, whereas retention times in the reticulorumen and in the whole tract decreased, as intake increased from maintenance energy requirements to 1.5 times maintenance.

Aging↗

Study on catalytic incineration of methane using Cr2O3/gamma-Al2O3 as the catalyst.

A fixed bed reactor was employed to investigate the catalytic incineration of CH4 by various supported transition metal oxide catalysts, with a view of finding the optimal one. Results indicated that the active species, the support, the metal content, the weight hourly space velocity (WHSV), and the inlet CH4 concentration were all important factors affecting CH4 oxidation. Cr2O3/gamma-Al2O3 was found to be the most active catalyst among the seven gamma-Al2O3-supported metal oxide catalysts tested. With Cr2O3 as the active species, gamma-Al2O3 was the most suitable of six supports tested. Furthermore, the optimal Cr content of Cr2O3/ gamma-Al2O3 was 9 wt.%. X-ray diffraction (XRD) patterns showed that it was formation of CrO3 crystals that caused a decline in catalyst activity at Cr content above 9wt.%. Using the optimal Cr2O3/gamma-Al2O3 catalyst, CH4 was completely oxidized at about 390 degrees C. much lower than the temperature required by noble metal catalysts for the same outcome. The stability of Cr2O3/gamma-Al2O3 was good and was not affected by the reaction temperature, demonstrated by a nearly constant conversion rate of CH4 of 57% at 350 degrees C and 97% at 380 degrees C during a 20 h on-stream test. However, WHSV and inlet concentration of CH4 did affect CH4 conversion noticeably. For complete oxidation of CH4, the reaction temperature required increased with WHSV and inlet CH4 concentration.

Air Pollution↗

Trivalent chromium inhibits protein glycosylation and lipid peroxidation in high glucose-treated erythrocytes.

Epidemiological studies have shown lower levels of chromium among men with diabetes and cardiovascular disease (CVD) compared with healthy control subjects. The mechanism by which chromium may decrease the incidence of CVD and insulin resistance is not known. Using erythrocytes as a model, this study demonstrates that chromium inhibits the glycosylation of proteins and oxidative stress, both risk factors in the development of CVD. Erythrocytes were treated with high levels of glucose (mimicking diabetes) in the presence or absence of chromium chloride in the medium at 37 degrees C for 24 hours. Chromium supplementation prevented the increases in protein glycosylation and oxidative stress caused by the high levels of glucose in erythrocytes. This study demonstrates for the first time that chromium supplementation inhibits protein glycosylation in erythrocytes exposed to high glucose medium, which appears to be mediated by its antioxidative effect. This provides evidence for a novel mechanism by which chromium supplementation may decrease incidence of CVD in diabetic patients.

Chlorides↗

Effect of chromium chloride supplementation on glucose tolerance and serum lipids including high-density lipoprotein of adult men.

Chromium deficiency may cause insulin resistance, hyperinsulinemia, impaired glucose tolerance, and hyperlipidemia, recovered by chromium supplementation. The effect of chromium supplementation on serum lipids and glucose tolerance was tested in a double-blind 12-wk study of 23 healthy adult men aged 31 to 60 yr. Either 200 micrograms trivalent chromium in 5 ml water (Cr) or 5 ml plain water (W) was ingested daily 5 days each week. Half the subjects volunteered for glucose tolerance tests with insulin levels. At 12 wk high-density lipoprotein cholesterol increased in the Cr group from 35 to 39 mg/dl (p less than 0.05) but did not change in the water group (34 mg/dl). The largest increase in high-density lipoprotein cholesterol and decreases in insulin and glucose were found in those subjects having normal glucose levels together with elevated insulin levels at base-line. The data are thus consistent with the hypothesis that Cr supplementation raises high-density lipoprotein cholesterol and improves insulin sensitivity in those with evidence of insulin resistance but normal glucose tolerance.

Adult↗