Effects of Combined Dietary Chromium(III) Propionate Complex and Thiamine Supplementation on Insulin Sensitivity, Blood Biochemical Indices, and Mineral Levels in High-Fructose-Fed Rats

Insulin resistance is the first step in glucose intolerance and the development of type 2 diabetes mellitus, thus effective prevention strategies should also include dietary interventions to enhance insulin sensitivity. Nutrients, such as microelement chromium(III) and thiamine, play regulatory roles in carbohydrate metabolism. The objective of this study was to evaluate the insulin-sensitizing potential of the combined supplementary chromium(III) propionate complex (CrProp) and thiamine in insulin resistance animal model (rats fed a high-fructose diet). The experiment was carried out on 40 nine-week-old male Wistar rats divided into five groups (eight animals each). Animals were fed ad libitum: the control diet (AIN-93?M) and high-fructose diets with and without a combination of two levels of CrProp (0.1 and 1?mg Cr/kg body mass/day) and two levels of thiamine (0.5 and 10?mg/kg body mass/day) for 8?weeks. At the end of the experiment rats were sacrificed to collect blood and internal organs for analyses of blood biochemical and hematologic indices as well as tissular microelement levels that were measured using appropriate methods. It was found that both supplementary CrProp and thiamine (given alone) have significant insulin-sensitizing and moderate blood-lipid-lowering properties, while the combined supplementation with these agents does not give synergistic effects in insulin-resistant rats. CrProp given separately increased kidney Cu and Cr levels, while thiamine alone increased hepatic Cu contents and decreased renal Zn and Cu contents.     

Chromium in the environment: factors affecting biological remediation

Chromium, in the trivalent form (Cr(III)), is an important component of a balanced human and animal diet and its deficiency causes disturbance to the glucose and lipids metabolism in humans and animals. In contrast, hexavalent Cr (Cr(VI)) is highly toxic carcinogen and may cause death to animals and humans if ingested in large doses. Recently, concern about Cr as an environmental pollutant has been escalating due to its build up to toxic levels in the environment as a result of various industrial and agricultural activities. In this review, we present the state of knowledge about chromium mobility and distribution in the environment and the physiological responses of plants to Cr with the desire to understand how these processes influence our ability to use low cost, environmentally friendly biological remediation technologies to clean up Cr-contaminated soils, sediments, and waters. The use of biological remediation technologies such as bioremediation and phytoremediation for the cleanup of Cr-contaminated areas has received increasing interest from researchers worldwide. Several methods have been suggested and experimentally tested with varying degrees of success.     

The justification for providing dietary guidance for the nutritional intake of boron

Because a biochemical function has not been defined for boron (B), its nutritional essentiality has not been firmly established. Nonetheless, dietary guidance should be formulated for B, because it has demonstrated beneficial, if not essential, effects in both animals and humans. Intakes of B commonly found with diets abundant in fruits, vegetables, legumes, pulses, and nuts have effects construed to be beneficial in macromineral, energy, nitrogen, and reactive oxygen metabolism, in addition to enhancing the response to estrogen therapy and improving psychomotor skills and cognitive processes of attention and memory. Perhaps the best-documented beneficial effect of B is on calcium (Ca) metabolism or utilization, and thus, bone calcification and maintenance. The paradigm emerging for the provision of dietary guidance that includes consideration of the total health effects of a nutrient, not just the prevention of a deficiency disease, has resulted in dietary guidance for chromium (Cr) and fluoride; both of these elements have beneficial effects in humans, but neither has a defined biochemical function. Knowledge of B nutritional effects in humans equals or is superior to that of Cr and fluoride; thus, establishing a dietary reference intake for B is justified. An analysis of both human and animal data suggests that an acceptable safe range of population mean intakes of B for adults could well be 1–13 mg/d. Recent findings indicate that a significant number of people do not consistently consume more than 1 mg B/d; this suggests that B could be a practical nutritional or clinical concern.     

含Cr(Ⅵ)电镀废水处理研究进展

铬的毒性与其存在状态有关,六价铬是电镀含铬废水中的主要特征污染物。综述了电镀废水中六价铬污染相关研究的近期进展。分析了水体中六价铬污染主要来源,介绍了水体中六价铬对水生生物的毒性研究概况,包括六价铬被水生生物吸收后在生物体内的积累和分布状况以及所导致的形态学、生物化学和超微结构上的伤害,介绍了电镀含铬废水常用的几种处理方法,包括离子交换树脂法、化学沉淀法、电化学法、吸附法等,重点介绍了生物除铬新技术的优点及其发展前景,最后阐述了代铬镀层的发展趋势,从源头减少六价铬的污染。     

Chromium metabolism

The trivalent state of chromium (Cr³⁺) is that encountered in biological milieus and is responsible for its nutritional activity. The principal route by which trivalent chromium enters the body is the digestive system. Chromium in foods is present both in the inorganic form and as organic complexes. Intestinal absorption of chromium is low (0.5–2%), and the mechanism has not yet been fully elucidated. Absorbed chromium circulates as free Cr³⁺, as Cr³⁺ bound to transferrin or other plasma proteins, or as complexes, such as glucose tolerance factor (GTF)-Cr. Circulating trivalent chromium can be taken up by tissues, and its distribution in the body depends on the species, age, and chemical form. It is excreted primarily in the urine by glomerular filtration or bound to a low-mol-wt organic transporter. Chromium metabolism is still imperfectly understood. The use of⁵¹Cr has nevertheless furnished valuable data concerning its transport and excretion.     

水稻对砷的吸收及代谢机制研究进展

砷（As）是一种广泛存在的致癌的微量元素。环境中日益严重的As污染问题,影响了水稻的生长和品质,并通过食物链进一步威胁着人类健康。为降低食物链中As的污染并提高水稻对As的耐性,需要深入了解水稻对As的吸收及As在水稻体内转运、代谢过程的生理及分子生物学机制。本文就以上几个问题综述了近些年来国内外的研究结果,并对今后深入研究提出建议。     

Ameliorating effect of chromium administration on hepatic glucose metabolism in streptozotocin-induced experimental diabetes

Chromium has been recognized as an essential trace element that plays an important role in carbohydrate metabolism. However, the molecular mechanisms involved in its action are not clear. This study was undertaken to understand the mechanism of chromium action in experimental diabetes. Streptozotocin-induced diabetic animals were administered chromium as chromium picolinate (CrP) at a daily dose of 1 mg/kg body weight for a period of 4 weeks. It was observed that chromium complexed with picolinate was effective in lowering plasma glucose levels as well as was able to alleviate polyphagia, polydipsia, and weight loss in diabetic animals. Administration of chromium was also found to normalize glycogen content in liver of diabetic animals to near control levels. The reduction in plasma glucose levels by chromium was accompanied by increase in activity of glycolytic enzymes (e.g., glucokinase, phosphofructokinase, and pyruvate kinase) and by suppression in activity of gluconeogenic enzymes (e.g., glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) in liver. Hepatic glucose uptake was found to be increased by chromium supplementation as demonstrated by decrease in Km and increase in Vmax values in diabetic animals. Chromium levels were lower in the liver of diabetic rats when compared with that of control rats. A negative correlation was observed between plasma glucose and chromium concentration in patients with diabetes. The data suggests that chromium supplementation as CrP is beneficial in correcting hyperglycemia, implying that the modulation of the glucose metabolism by chromium may be therapeutically beneficial in the treatment of diabetes.     

Theoretical and methodological bases of experimental simulation of the prepathological state under membrane-damaging effects of environmental factors

The paper theoretically substantiates the importance for detecting the prepathological state of experimental simulation of those situations in the organism which adequately reflect changes in human metabolism exposed to multiple environmental factors. A putative experimental model has been proposed in the shape of sexually immature and mature generations of animals of differing age with a "metabolic burden" whose characteristics, as regards impairments in biochemical, immunological and other functional reactions in biological fluids, are to some extent similar to those occurring in certain groups of humans. It has been suggested that the further investigation of the mechanisms and biological significance of systemic changes of the body's internal milieu may hold promise for studies of environmental hygiene in evaluating populational health and detecting the early signs of metabolic alterations with the aim of their timely prevention.     

Is chromium a trace essential metal?

If chromium is an essential metal it must have a specific role in an enzyme or cofactor, and a deficiency should produce a disease or impairment of function. To date, no chromium-containing glucose tolerance factor has been characterized, the purpose of the low-molecular-weight chromium-binding protein is questionable, and no direct interaction between chromium and insulin has been found. Furthermore, chromium3+ is treated like the toxic metals arsenic, cadmium, lead and mercury in animals. Chromium3+ may be involved in chromium6+-induced cancers because chromium6+ is converted to chromium3+ in vivo, and chromium3+ is genotoxic and mutagenic. Although there is no direct evidence of chromium deficiencies in humans, dietary supplements exist to provide supraphysiological doses of absorbable chromium3+. Chromium3+ may act clinically by interfering with iron absorption, decreasing the high iron stores that are linked to diabetes and heart disease. If so, this would make chromium3+ a pharmacological agent, not an essential metal.     

Hematological effects of aluminum on living organisms

1. Aluminum has been of great interest for many researchers over a number of years; its biochemical and physiological role is not yet fully clear. There are few papers describing the hematological consequences of its excess in living organisms and most of their data are cited in this paper.2. Aluminum reduced the deformability of erythrocytes, and such cells are rather frequently retained in the reticuloendothelial system of the spleen and eliminated faster from the blood stream.3. Aluminum produces peroxidative changes in the erythrocytes membrane, leading to hemolysis. Therefore, the depressed erythrocyte count in animals intoxicated with aluminum may be the consequence of both the hemolytic action of aluminum and the shortened time of survival of erythrocytes.4. It was demonstrated that aluminum inhibits heme biosynthesis in vitro. This problem requires, however, further studies and observation.5. Changes occurring under the influence of Al³⁺ on the leukocyte system of animals suggest the influence of this element on the resistance of the organism, but the mechanism of the action of A1³⁺ still requires elucidation.6. Cell metabolism including blood cells may be affected by aluminum in many ways, the more so as the element may combine in vitro with amino acids, peptides, proteins, enzymes, substrates, cofactors, nucleotides and carbohydrates. Aluminum stimulates NADPH oxidation and takes part in the process of free radical formation.     

Advances in our understanding of vitamin E

Vitamin E is an essential nutrient for animals and man since it is not synthesized in the body. The level of vitamin E in the lipoproteins of plasma and in the phospholipids of vital mitochondria, microsomes, and plasma membranes in humans depends (as in experimental animals) on the amount of biologically active vitamin E being consumed, the levels of dietary prooxidants and antioxidants, and the adequacy of dietary selenium. Studies with chicks have demonstrated an important mode of action of both vitamin E and selenium in metabolism, and provide a solution to the long-term enigma of the true role of vitamin E in the diet of all animals, including man. The biochemical actions of vitamin E and selenium are concerned with prevention of peroxidative damage to cells and subcellular elements, thereby aiding the body in maintaining its normal defense mechanisms against disease and environmental insult.     

Effect of chromium ions on the function of neuromuscular junctions

It has been shown on neuro-muscular preparations of frog sartorius muscle that chromium ions in the concentrations 1-4 x 10(-6) g/ml strengthen spontaneous and evoked transmitter release. Cr3+ ions in the concentrations above 4 x 10(-6) g/ml decrease the membrane potential of muscle fibres, decrease the quantum content of the end plate potentials. Experiments on a single Ranvier node have shown that Cr3+ ions decrease the amplitude, increase the rate and duration of the action potential of a nerve fibre. It is concluded that chromium ions produce a pronounced effect on synaptic transmission, which differs significantly from the action of manganese, cobalt and nickel ions.     

Chromium(III)-insulin derivatives and their implication in glucose metabolism

Insulin has been reacted with five chromium(III) complexes that are capable of relatively facile substitution of aquo ligands. The new Cr(III) insulin derivatives have been characterized by means of electronic and infrared spectra, and evidence for major changes in the protein structure, including the state of aggregation, has been presented. Supporting evidence for the arguments favoring the beneficiary role of chromium(III) in glucose metabolism has been obtained using in vivo studies, and it has been shown that insulin derived with Cr(salen) (H2O)2+ is capable of reversing the blood sugar, serum cholesterol, and phospholipids levels to those of normal rats. The results emphasize the dependence of biopotency on the structure of Cr(III) complexes used for derivation of insulin and discount the postulates that Cr(III) serves to assemble insulin and receptor units through metal-sulphur bonding. The influence of Cr(III) on the structural stability and state of aggregation of insulin and their possible role in glucose metabolism is discussed.     

Determination of chromium(III) in aqueous solution using CePO4:Tb3+ nanocrystals in a fluorescence resonance energy transfer system

Trivalent chromium is an essential element required for normal carbohydrate, lipid and protein metabolism in humans and animals. This article describes an efficient fluorescence resonance energy transfer (FRET) system between CePO₄:Tb³⁺ nanocrystals as the donor and chromium(III) as the acceptor. CePO₄:Tb³⁺ nanocrystals were synthesized in aqueous solution, and characterized by transmission electron microscopy. Under optimum conditions, a linear calibration graph was obtained (R² = 0.996). The linear range and detection limit of chromium(III) were 0.01–2.2 μM, and 9.1 nM, respectively. The proposed method had a wide linear range and proved to be very sensitive, rapid and simple. Moreover, the method was applied successfully to the determination of chromium(III) in synthetic samples and tap water. Copyright © 2013 John Wiley & Sons, Ltd.     

两种价态铬(Ⅲ,Ⅵ)对真核酵母细胞谷胱甘肽水平影响

工业的迅猛发展使得重金属污染加剧,得到了人们的广泛关注。铬(Cr)在化工业中的广泛应用,使其成为一种主要的环境污染重金属离子。酿酒酵母是研究金属毒性最常用的生物之一。本文比较了三种铬盐(三氯化铬、三氧化铬、重铬酸钾)对酿酒酵母生长的影响,半抑制浓度的两种价态铬(Cr^3+,Cr^6+)处理酵母细胞,Cr^6+引起细胞的致死率更高。已有研究表明谷胱甘肽是胞内重要的还原剂,常用于细胞的重金属解毒,因此探究了两种价态的铬对酵母胞内谷胱甘肽水平的影响。结果显示重铬酸钾和三氧化铬浓度的升高都会引起胞内含量显著降低,而三氯化铬基本不变,过表达GSH1基因有利于提高酵母细胞对Cr^6+的抗性,但对Cr^3+没有明显效果,这说明两种价态铬在胞内生化作用方式不同,细胞应对的解毒机制也不一样。该研究对工业含铬废弃物处理和微生物治理环境污染提供了理论依据。     

Molecular basis of chromium insulin interactions

The physiological role of chromium (III) in diabetes mellitus has been an area of inconclusive research for many years. It is of great interest to explore the interactions made by chromium (III) to get a better insight into their role in glucose metabolism. To understand the molecular basis of chromium action we have carried out spectroscopic and crystallographic investigations on the binding of Cr(III)-Salen with insulin, as Cr(III)-Salen is reported to result in the enhancement of insulin activity. The Cr(III)-insulin complex formation has been characterised at two pHs, viz., 3.5 and 9.0 using UV-Vis and fluorescence studies. The crystallographic analysis of Cr(III)-Salen soaked cubic insulin crystals, using anomalous difference Fourier method, revealed B21 Glu to be the binding site for chromium (III).     

Effect of chromium (III) ions and a cysteine complex of it on lipid bilayer membranes]

The interaction of Cr3+ ions and its cysteine complex with bilayer phospholipid membranes was investigated. It was found that chromium ions and the complex compound are adsorbed on the bilayer lipid membrane surface, changing the intramembrane potential difference. As pH increases, the adsorption of Cr3+ decreases and that of the complex rises. The adsorption of the complex leads to an increase in the rigidity of bilayer lipid membrane, which is not observed with chromium ions.     

Should bioactive trace elements not recognized as essential,but with beneficial health effects,have intake recommendations

Today, most nutritionists do not consider a trace element essential unless it has a defined biochemical function in higher animals or humans. As a result, even though it has been found that trace elements such as boron and silicon have beneficial bioactivity in higher animals and humans, they generally receive limited attention or mention when dietary guidelines or intake recommendations are formulated. Recently, the possibility of providing dietary intake recommendations such as an adequate intake (AI) for some bioactive food components (e.g., flavonoids) has been discussed. Boron, chromium, nickel, and silicon are bioactive food components that provide beneficial health effects by plausible mechanisms of action in nutritional and supra nutritional amounts, and thus should be included in the discussions. Although the science base may not be considered adequate for establishing AIs, a significant number of findings suggest that statements about these trace elements should be included when dietary intake guidance is formulated. An appropriate recommendation may be that diets should include foods that would provide trace elements not currently recognized as essential in amounts shown to reduce the risk of chronic disease and/or promote health and well-being.     

Molecular and cellular bases of iron metabolism in humans

Iron is a microelement with the most completely studied biological functions. Its wide dissemination in nature and involvement in key metabolic pathways determine the great importance of this metal for uniand multicellular organisms. The biological role of iron is characterized by its indispensability in cell respiration and various biochemical processes providing normal functioning of cells and organs of the human body. Iron also plays an important role in the generation of free radicals, which under different conditions can be useful or damaging to biomolecules and cells. In the literature, there are many reviews devoted to iron metabolism and its regulation in proand eukaryotes. Significant progress has been achieved recently in understanding molecular bases of iron metabolism. The purpose of this review is to systematize available data on mechanisms of iron assimilation, distribution, and elimination from the human body, as well as on its biological importance and on the major iron-containing proteins. The review summarizes recent ideas about iron metabolism. Special attention is paid to mechanisms of iron absorption in the small intestine and to interrelationships of cellular and extracellular pools of this metal in the human body.     

The effect of chromium on parameters related to iron metabolism

The effect of chromium on some parameters related to iron metabolism was investigated. Preliminary experiments showed that this metal ion was taken up by serum proteins and was dependent on the amount of chromium present in the medium. It was also shown that the uptake of iron was reduced significantly in the presence of chromium. In vivo study showed that the serum levels of iron and total iron binding capacity (TIBC) were reduced by 28 and 11%, respectively, following daily administration of chromium (1 mg/kg) for 45 d. Serum ferritin was reduced by 22% under this condition. Hematocrit and hemoglobin levels were also affected in chromium-treated animals and were both reduced by 17%. Spectrophotometric titration of each individual amino acid located in the iron binding site of transferrin revealed that tyrosin might be the most suitable ligand for the binding of chromium to transferrin. These results suggest that chromium may compete with iron in binding to apo-transferrin, and influence iron metabolism and its related biochemical parameters.