Is the Pharmacological Mode of Action of Chromium(III) as a Second Messenger?

Chromium picolinate supplementation improves cardiac performance in hypoxic rats

BACKGROUND

Conditions associated with chronic hypoxia increase morbidity and mortality attributable to cardiovascular complications. Myocardial hypoxia is a common feature in several diseases including: stroke, infarction, anaemia, chronic lung diseases, obstructive sleep apnoea and cyanotic congenital heart defects. The present study was planned to investigate the cardiovascular effects of chronic intermittent hypoxia and its association with increased myocardial oxidative stress. In addition, to evaluate the protective effect of chromium supplementation, aiming at achieving an alternative that may enable to devise a therapy for hypoxic patients.

METHODS

Male rats were allocated into three groups: control group (normoxic), untreated hypoxic group (exposed to hypoxia 8 h/day, 5 days/week for 6 weeks) and hypoxic group supplemented with chromium picolinate (90 µg/kg/day by gavage). Rats were subjected to measurement of body weight, haematocrit value, mean arterial blood pressure, heart rate and ECG recording. Cardiac activities of isolated hearts were studied on Langendorff preparation under basal conditions and in response to ischaemia/reperfusion. Thereafter, cardiac weights were determined and cardiac tissue catalase activity as well as malondialdhyde level were assessed.

RESULTS

Significant results were obtained upon exposure to hypoxia including; low body weight, increased haematocrit, elevated blood pressure, left ventricular hypertrophy and impaired cardiac activities, basally and in response to ischaemia/reperfusion challenges, associated with increased oxidative stress in cardiac tissue. At the same time, chromium supplementation increased body weight, lowered blood pressure, reduced ventricular hypertrophy and significantly improved the cardiac performance.

CONCLUSION

Chromium supplementation confers protection against hypoxia-induced cardiovascular dysfunction by improvement of the antioxidant capacity.

Understanding Cr(III) Action on Mitochondrial ATP Synthase and AMPK Efficacy: Insights from Previous Studies-a Review

Chromium supplementation has been notably recognized for its potential health benefits, especially in enhancing insulin sensitivity and managing glucose metabolism. However, recent studies have begun to shed light on additional mechanisms of action for chromium, expanding our understanding beyond its classical effects on the insulin-signaling pathway. The beta subunit of mitochondrial ATP synthase is considered a novel site for Cr(III) action, influencing physiological effects apart from insulin signaling. The physiological effects of chromium supplementation have been extensively studied, particularly in its role in anti-oxidative efficacy and glucose metabolism. However, recent advancements have prompted a re-evaluation of chromium's mechanisms of action beyond the insulin signaling pathway. The discovery of the beta subunit of mitochondrial ATP synthase as a potential target for chromium action is discussed, emphasizing its crucial role in cellular energy production and metabolic regulation. A meticulous analysis of relevant studies that were earlier carried out could shed light on the relationship between chromium supplementation and mitochondrial ATP synthase. This review categorizes studies based on their primary investigations, encompassing areas such as muscle protein synthesis, glucose and lipid metabolism, and antioxidant properties. Findings from these studies are scrutinized to distinguish patterns aligning with the new hypothesis. Central to this exploration is the presentation of studies highlighting the physiological effects of chromium that extend beyond the insulin signaling pathway. Evaluating the various independent mechanisms of action that chromium impacts cellular energy metabolism and overall metabolic balance has become more important. In conclusion, this review is a paradigm shift in understanding chromium supplementation, paving the way for future investigations that leverage the intricate interplay between chromium and mitochondrial ATP synthase.

Chromium in the Diet of Dairy Calves: Benefits for Growth Performance, Feed Efficiency, Digestibility, and Health

Chromium (Cr) is a mineral that helps animals subjected to stressful conditions. The suckling period is characterized by several stressful episodes, particularly during the first hours after birth and at weaning. There is little consumption of concentrate by calves in the first weeks of life; consequently, consuming any supplement added to feed would be negligible. Thus, the hypothesis was that the calves would take it in earlier if Cr were consumed in a milk replacer instead. Therefore, our study aimed to determine whether including organic Cr in calf feed (via milk replacer or concentrate) during the suckling phase would improve calf health and growth performance. Twenty-four male Holstein calves with an average age of 8 ± 4 days and 39.8 ± 6.9 kg average body weight were used. Calves were randomly divided into three groups: (a) Chromium-Milk (CR-M), receiving 4 mg Cr/animal/day via milk replacer during the 60 experimental days of suckling (n = 8); (b) Chromium-Concentrate (CR-C), receiving 4 mg Cr/animal/day via concentrate (n = 8); (c) Control (C), animals that did not receive Chromium (n = 8). The experiment lasted 75 days, divided into two well-defined stages: suckling (1-60 days) and weaning (61-75 days). Body weight weekly, daily feed intake, and blood samples taken every two weeks during the experiment were evaluated. At the end of the experiment, the apparent digestibility evaluation was carried out, with the results of weight and consumption carried out, and a feed efficiency analysis was carried out. It was observed that the inclusion of organic Cr (regardless of whether it was milk or concentrate) increased body weight gain (kg) for the CR-C group: 41.8 kg, CR-M: 40.4 kg compared to the C: 34.2 kg (p = 0.01). The protein digestibility was higher in the CR-M group (52%, p = 0.05). Cr consumption increased Cr concentrations in the serum of the calves and was higher in the first week in the animals in the CR-M group. This did not happen for the C group; however, with higher concentrate consumption, Cr concentrations increased and remained high until the end of the experiment. Glucose concentrations were higher in the groups that consumed Cr. Total protein concentrations were higher in the CR-M and CR-C groups than in group C. Immunoglobulin A concentrations were higher in groups CR-C and CR-M than in group C (days 40 and 60). In conclusion, the adding Cr to calf feed improves their health, indirectly favors growth performance, and increases protein digestibility.

Does the peroral chromium administration in young Hariana calves reduce the risk of calf diarrhea by ameliorating insulin response, lactose intolerance, antioxidant status, and immune response?

BACKGROUND

The reduction in insulin sensitivity during rumen development may predispose dairy calves towards lactose intolerance, which could be the reason behind neonatal calf diarrhea (NCD). Chromium (Cr) results in a range of effects when fed to ruminants, but most studies have shown improved insulin sensitivity. The aim of this study was to determine the effect of Cr supplementation on insulin sensitivity, lactose intolerance, diarrhoea and antioxidant, and immune response in young Hariana calves.

METHODS

A total of 20 milk-fed Hariana calves were randomly assigned to 1 of 2 treatments, each consisted of 10 calves: (1) a control group without supplemental Cr and (2) a 0.15 mg Cr as Cr-picolinate (CrPic)/kg BW0.75 supplemented group (Cr0.15).

RESULTS

A more rapid glucose disappearance with unaltered insulin kinetics during intravenous glucose tolerance test (IVGTT) and oral lactose tolerance test (OLTT) indicates greater insulin sensitivity in Cr supplemented calves. Better insulin sensitivity in Cr supplemented calves was further confirmed by higher values of the quantitative insulin sensitivity check index (QUICKI), revised quantitative insulin sensitivity check index (RQUICKI) and insulin receptor substrate-1 (IRS-1) and lower (P < 0.05) values of homeostasis model assessment-insulin resistance (HOMA-IR) and glucose-to-insulin ratio in Cr supplemented calves during IVGTT. Cr supplementation resulted in a lower (P < 0.05) serum cortisol concentration, whereas serum non-esterified fatty acid (NEFA) concentrations during IVGTT did not differ among the groups. The rise in serum glucose concentrations within 2 h post lactose infusion during OLTT peaked at more than twice the basal glucose concentration, therefore calves were not considered as lactose intolerant. Within monthly blood samples, concentrations of serum insulin were similar among treatments, whereas the Cr supplemented group had lower (P < 0.05) serum glucose concentration and glucose-to-insulin ratio compared with the control group. No treatment differences were detected in the biomarkers of antioxidant status and immunity. Serum Cr concentrations were higher (P < 0.05) in Cr supplemented calves while concentrations of other studied minerals were remained unaltered. The incidence, duration of diarrhea, and faecal score were better (P < 0.05) in calves fed on Cr supplemented diet whereas, no treatment effect was observed on average daily gain (ADG). During the study period, no calves died, and no calves were found to have pneumonia, navel or joint disease.

CONCLUSION

Feeding a Cr-supplemented diet improved insulin sensitivity and reduced the risk of diarrhoea in milk-fed young calves, but had no or minimal effects on lactose intolerance, antioxidant status, immune response, and growth performance.

Insulin-like growth factor 1 in heat stress-induced neuroinflammation: novel perspective about the neuroprotective role of chromium

Heat stress (HS) can cause a series of stress responses, resulting in numerous negative effects on the body, such as the diminished food intake, carcass quality and reproductive capacity. In addition to the negative effects on the peripheral system, HS leads to central nervous system (CNS) disorders given its toll on neuroinflammation. This neuroinflammatory process is mainly mediated by microglia and astrocytes, which are involved in the activation of glial cells and the secretion of cytokines. While the regulation of inflammatory signaling has a close relationship with the expression of heat shock protein 70 (Hsp70), HS-induced neuroinflammation is closely related to the activation of the TLR4/NF-κB pathway. Moreover, oxidative stress and endoplasmic reticulum (ER) stress are key players in the development of neuroinflammation. Chromium (Cr) has been widely shown to have neuroprotective effects in both humans and animals, despite the lack of mechanistic evidence. Evidence has shown that Cr supplementation can increase the levels of insulin-like growth factor 1 (IGF-1), a major neurotrophic factor with anti-inflammatory and antioxidant effects. This review highlights recent advances in the attenuating effects and potential mechanisms of Cr-mediated IGF-1 actions on HS-induced neuroinflammation, providing presently existing evidence supporting the neuroprotective role of Cr.

Dietary Chromium Picolinate Supplementation Improves Glucose Utilization in Transition Calf by Ameliorating Insulin Response

The decrease in insulin sensitivity during the transition of preruminant calves into ruminant animals is the common denominator. Meanwhile, this adaptation predisposes dairy calves towards various health issues and metabolic disorders that occur in later life. Chromium (Cr) has been shown to potentiate insulin functioning and is thereby helpful in reducing the risk of these metabolic disorders. The aim of this study was to assess the effect of Cr supplementation on the insulin sensitivity and health status in Hariana calves during their transition period. A total of 24 preruminant Hariana calves were randomly allocated into four groups (6 calves per group) for a period of 90 days. Calves either received a basal diet devoid of supplemental Cr (control; Cr_0.0 group) or were supplemented with 0.05 mg (Cr_0.05 group), 0.10 mg (Cr_0.10 group), and 0.15 mg (Cr_0.15 group) of Cr per kg BW^0.75 as Cr-picolinate (Cr-Pic). To determine the effect of Cr supplementation on the insulin response, glucose-insulin-non-esterified fatty acids (NEFAs) kinetics was studied during the intravenous glucose tolerance test (IVGTT) and oral glucose tolerance test (OGTT). A rapid glucose disappearance (p < 0.05) with unaltered insulin kinetics during IVGTT and OLTT indicates greater insulin sensitivity in calves supplemented with 0.10 and 0.15 mg of Cr per kg BW^0.75. Improved insulin sensitivity in the Cr_0.10 and Cr_0.15 groups was further confirmed by higher (p < 0.05) values of the insulin sensitivity check index (QUICKI), revised quantitative insulin sensitivity check index (RQUICKI), and lower (p < 0.05) values of the homeostasis model assessment-insulin resistance (HOMA-IR) during IVGTT. Mean serum non-esterified fatty acids (NEFA_m), and insulin receptor substrate-1 (IRS-1) levels were the highest (p < 0.05) and cortisol concentrations were the lowest (p < 0.05) in the Cr_0.15 groups. Unlike IVGTT, there was no effect of treatment, period, and treatment × period interaction on mean serum glucose and insulin levels during OGTT. However, Cr-supplemented calves had a higher (p < 0.05) glucose clearance rate (_gCR). Serum IRS-1 concentrations during OGTT were also higher (p < 0.05) in the Cr_0.10 and Cr_0.15 groups than in the other groups. Serum Cr levels increased dose dependently and were the highest (p < 0.05) in calves fed a diet supplemented with 0.15 mg Cr per kg BW^0.75. There was no effect of treatment on average daily gain (ADG) and body condition score (BCS) while frequency and duration of diarrhea were lower and fecal score was better in Cr-supplemented calves. The current findings show that Cr supplementation improved glucose utilization and health status in calves during their transition period by improving insulin sensitivity.

Plasma metabolic profiling reveals that chromium yeast alleviates the negative effects of heat stress in mid-lactation dairy cows

Chromium yeast (CY) supplementation has the potential to alleviate the negative effects of heat stress in dairy cows, but the mechanism remains elusive. We aimed to identify the metabolic mechanisms whereby CY supplementation alleviates the negative effects of heat stress in mid-lactation dairy cows. Twelve Holstein dairy cows with similar milk yield (24.6 ± 1.5 kg/d), parity (2 or 3) and days in milk (125 ± 8 d) were fed the same basal diet containing 0.09 mg of Cr/kg DM. They were allocated randomly to 2 groups: a control group (CON, without CY supplementation) and a CY group (CY, administered 0.36 mg Cr/kg DM). The experiment was performed over 8 weeks during a hot summer, in which the mean temperature-humidity index was 79.0 ± 3.13 (>72), indicating that the dairy cows were exposed to heat stress. Chromium yeast supplementation reduced rectal temperature (P = 0.032), and increased the lactation performance by increasing the yield of milk (+2.6 kg/d), protein, lactose and total solid, and protein and lactose percentages in the milk of the heat-stressed dairy cows (P < 0.05). Supplementation with CY increased the serum glucose and thyroxine concentrations, but reduced the urea nitrogen, insulin, and triiodothyronine concentrations on d 56 (P < 0.05). Furthermore, plasma metabolomic analysis was performed using liquid chromatography tandem-mass spectrometry, which identified 385 metabolites in the two groups. Subsequently, 16 significantly different metabolites in the plasma, were significantly higher in the CY group (variable importance for the projection >1.0, P < 0.05), and found to be involved in 6 Kyoto Encyclopedia of Genes and Genomes pathways, including those involved in nicotinate and nicotinamide metabolism. Specifically, plasma concentration of nicotinamide was higher after CY supplementation, which might also contribute to the reduction of rectal temperature, the regulation of glucose homeostasis, and an improvement in the lactation performance of heat-stressed dairy cows. In conclusion, CY supplementation reduces rectal temperature, influences metabolism by reducing serum insulin concentration and increasing serum glucose and plasma nicotinamide concentrations, and finally increases lactation performance of heat-stressed dairy cows.

Chocolate byproducts and protected fats enriched with chromium to replace corn in diets of early lactation Holstein cows: feed utilization, blood profile, and lactational performance

The present experiment aimed to evaluate the partial replacement of corn with chocolate byproducts or protected fats in the diet of lactating cows on feed utilization, blood profile and lactation performance. Fifty multiparous Holstein cows (560±22 kg BW, 3±1 parity, 7±1 days in milk, and previous milk production of 34±3 kg/d), were randomly assigned to 5 treatments in a completely randomized design for 90 days. The control diet contained a concentrate feed mixture containing (per kg DM 412 g concentrate feed mixture, 412 g corn silage, and 176 g berseem hay). The control diet contained 17.6% crushed corn (DM basis). In another treatment, the control diet was supplemented with 1 g chromium daily (Chromium diet). In the other diets, each kg of crushed corn grain was replaced with 600 g chocolate byproducts (CH diet), 400 g protected fats (PF diet), or 500 g of chocolate byproducts and protected fats mixture (1:1 DM basis) (CHPF diet), DM basis, and each of the diets was also supplemented with 1 g chromium daily. Both amounts of protected fats and chocolate byproducts had the same energy concentration as 1 kg of corn. Without affecting feed intake, the replacement increased (P<0.01) milk production, milk fat concentration, and feed efficiency. The replacement (P<0.05) increased the concentrations of serum total proteins, albumin, glucose, cholesterol, triglyceride, and chromium in comparison with the control diet. Higher (P<0.001) nutrient digestibility was observed with CH, PF, and CHPF treatments. It is concluded that chromium supplementation did not affect feed utilization or cows performance; however, partial replacement of corn with chromium supplemented protected fat, chocolate byproducts or their mixture improved milk production and feed efficiency.

The elements of life: A biocentric tour of the periodic table

Living systems are built from a small subset of the atomic elements, including the bulk macronutrients (C,H,N,O,P,S) and ions (Mg,K,Na,Ca) together with a small but variable set of trace elements (micronutrients). Here, we provide a global survey of how chemical elements contribute to life. We define five classes of elements: those that are (i) essential for all life, (ii) essential for many organisms in all three domains of life, (iii) essential or beneficial for many organisms in at least one domain, (iv) beneficial to at least some species, and (v) of no known beneficial use. The ability of cells to sustain life when individual elements are absent or limiting relies on complex physiological and evolutionary mechanisms (elemental economy). This survey of elemental use across the tree of life is encapsulated in a web-based, interactive periodic table that summarizes the roles chemical elements in biology and highlights corresponding mechanisms of elemental economy.

Steviol Glycoside, L-Arginine, and Chromium(III) Supplementation Attenuates Abnormalities in Glucose Metabolism in Streptozotocin-Induced Mildly Diabetic Rats Fed a High-Fat Diet

Stevia rebaudiana Bertoni and its glycosides are believed to exhibit several health-promoting properties. Recently, the mechanisms of the anti-diabetic effects of steviol glycosides (SG) have been the subject of intense research. The following study aims to evaluate the results of SG (stevioside (ST) and rebaudioside A (RA)) combined with L-arginine (L-Arg) and chromium(III) (CrIII) supplementation in streptozotocin- (STZ) induced mild type 2 diabetic rats fed a high-fat diet (HFD), with particular emphasis on carbohydrate and lipid metabolisms. The experiment was carried out on 110 male Wistar rats, 100 of which were fed an HFD to induce insulin resistance, followed by an intraperitoneal injection of streptozotocin to induce mild type 2 diabetes. After confirmation of hyperglycemia, the rats were divided into groups. Three groups served as controls: diabetic untreated, diabetic treated with metformin (300 mg/kg BW), and healthy group. Eight groups were fed an HFD enriched with stevioside or rebaudioside A (2500 mg/kg BW) combined with L-arginine (2000 or 4000 mg/kg BW) and Cr(III) (1 or 5 mg/kg BW) for six weeks. The results showed that supplementation with SG (ST and RA) combined with L-arg and Cr(III) could improve blood glucose levels in rats with mild type 2 diabetes. Furthermore, ST was more effective in improving blood glucose levels, insulin resistance indices, and very low-density lipoprotein cholesterol (VLDL-C) concentrations than RA. Although L-arg and Cr(III) supplementation did not independently affect most blood carbohydrate and lipid indices, it further improved some biomarkers when combined, particularly with ST. Notably, the beneficial impact of ST on the homeostatic model assessment–insulin resistance (HOMA-IR) and on the quantitative insulin-sensitivity check index (QUICKI) was strengthened when mixed with a high dose of L-arg, while its impact on antioxidant status was improved when combined with a high dose of Cr(III) in rats with mild type 2 diabetes. In conclusion, these results suggest that supplementary stevioside combined with L-arginine and Cr(III) has therapeutic potential for mild type 2 diabetes. However, further studies are warranted to confirm these effects in other experimental models and humans.

Impacts of Heat Stress on Rabbit Immune Function, Endocrine, Blood Biochemical Changes, Antioxidant Capacity and Production Performance, and the Potential Mitigation Strategies of Nutritional Intervention

Heat stress has become a widespread concern in the world, which is one of the major environmental stressors and causes substantial economic loss in the rabbit industry. Heat stress leads to multiple damages to the health of rabbits, such as organ damage, oxidative stress, disordered endocrine regulation, suppressed immune function and reproductive disorders, ultimately, induces the decreased production performance and increased mortality. Nutritional approaches, including feeding strategies, adjusting feed formula, and supplementing vitamins, minerals, electrolytes, Chinese herbal medicines, and functional active substances to the feed, were reported to mitigate the detrimental effects of heat stress in rabbits. Therefore, elucidating the damage of heat stress to rabbits; proper management and nutritional approaches should be considered to solve the heat stress issue in rabbits. This review highlights the scientific evidence regarding the effects of heat stress on rabbit's immune function, endocrine, blood biochemical changes, antioxidant capacity and production performance, and the potential mitigation strategies of nutritional intervention to alleviate heat stress in rabbits; which could contribute to develop nutritional strategies in relieving heat stress of rabbits.

Mineral Micronutrients in Asthma

Asthma represents one of the most common medical issues in the modern world. It is a chronic inflammatory disease characterized by persistent inflammation of the airways and disturbances in redox status, leading to hyperresponsiveness of bronchi and airway obstruction. Apart from classical risk factors such as air pollution, family history, allergies, or obesity, disturbances of the levels of micronutrients lead to impairments in the defense mechanisms of the affected organism against oxidative stress and proinflammatory stimuli. In the present review, the impact of micronutrients on the prevalence, severity, and possible risk factors of asthma is discussed. Although the influence of classical micronutrients such as selenium, copper, or zinc are well known, the effects of those such as iodine or manganese are only rarely mentioned. As a consequence, the aim of this paper is to demonstrate how disturbances in the levels of micronutrients and their supplementation might affect the course of asthma.

A Sensor for the Detection of Cr (III) and Fe (III) Ions Based on "Turn Off" Mechanism of Fluorescence with Computational Studies

A new and innovative fluorescent structure was constructed on Cyclotriveratrylene affiliated to Dansyl chloride (DNSC) and was used to detect Cr (III) and Fe (III) among the various cations by using spectrofluorimetric method. The characterization of the new compound was carried out using the ¹H-NMR, ¹³C-NMR, and ESI-MS techniques. The interaction and role of DNSC-CTV with cations was reviewed. A change in the spectra of absorption directed to the conclusion that there is substantial interaction of Cr (III) and Fe (III) with DNSC-CTV. Furthermore the interaction of the ligand DNSC-CTV with the metal ions Chromium (III) and Iron (III) showed quenching in the emission spectra. Quantum yield of the complexes were calculated and the stern volmer analysis was done to deduce the quenching mechanism of fluorescence to being either static or dynamic. The molecule DNSC-CTV was further studied with the help of computational methods such as molecular docking to study the binding interactions and properties of the molecule.

Effects of sodium bicarbonate and chromium propionate supplementation on growth performance, blood indices of Beetal bucks under heat stress

The objective of the current experiment was to determine the effects of sodium bicarbonate (SBC) and chromium propionate (Cr) supplementation on dry matter intake (DMI), growth performance, blood indices, feed sorting behavior, and digestibility of nutrients during the hot and humid condition in Beetal bucks. Twenty-eight Beetal bucks were randomly assigned to four concentrates treatments (n = 7 bucks/treatment) under 2 × 2 factorial arrangements. The factors were (1) chromium supplementation, basal diet without any supplementation (C) and basal diet with Cr @ 1.5 mg Cr/head/day (Cr), and (2) sodium bircbonate supplementation, basal diet supplemented with SBC @15 g/kg of DM (SBC) and diet containing SBC @ 15 g/kg of DM) and Cr @ 1.5 mg/day/animal (SBC + Cr). Chromium was drenched to each animal during the morning feeding. The average daily noon temperature-humidity index (THI) was 86.37 ± 4.01. The daily DMI and ADG was higher (P < .0001) in the SBC, and trend for daily DMI was observed (P < 0.01) for the Cr. The feed to gain ratio was tended to improve (P = 0.056) by the supplementation of Cr. Plasma glucose, cholesterol, and catalase concentration were lower (P < 0.05) in the Cr supplemented, whereas plasma BUN and TPP were not influenced (P > 0.05) by the Cr or the SBC supplementation. The feed selection index indicated that supplementation of Cr and SBC had no effects on selection or rejection of feed particles. In Cr-supplemented bucks, there was a trend for higher ADF digestibility. Digestibility of dry matter, organic matter, NDF, and ADF were not affected by Cr or SBC supplementation. In conclusion, co supplementation of Cr @ 1.5 mg/d and SBC @ 15 g/kg resulted in highest DMI, ADG and improved the feed efficiency in heat-stressed fattening bucks by alleviating negative impacts of HS.

Rosmarinus officinalis essential oil modulates renal toxicity and oxidative stress induced by potassium dichromate in rats

BACKGROUND

Chromium hexavalent (CrVI) is known as a toxic contaminant that induced oxidative stress and nephrotoxicity in humans and animals. Rosmarinus officinalis is a perennial herb rich in biologically active constituents that have powerful antioxidant properties. So, the current work evaluated the effectiveness of Rosmarinus officinalis essential oil (REO) against alterations induced by potassium dichromate in the kidney of male rats.

METHODS

GC-MS analysis, in vitro total phenol contents, and DPPH scavenging activity of REO were estimated. Thirty-five Wistar male rats were categorized into 5 groups. The first group was the control, the second one was orally administered rosemary essential oil (REO; 0.5 mL/kg BW), the third group was injected intraperitoneally with hexavalent chromium (CrVI; 2 mg/kg BW) for 14 days, the fourth group used as the protective group (REO was administrated 30 min before i.p. injection of CrVI) and the fifth group applied as the therapeutic group (rats injected with CrVI 30 min followed by oral administration of REO), respectively.

RESULTS

Twenty-nine components were detected with high total phenolic contents and high DPPH scavenging activity. Results revealed that CrVI- intoxicated rats showed a valuable increase in oxidative stress profile (TBARS and H₂O₂) and a notable decline in glutathione (GSH), total protein content, and enzymatic antioxidants (SOD, CAT, GPx, and GST). Furthermore, serum kidney functions biomarkers (urea, creatinine, and uric acid) were increased significantly. Also, the administration of CrVI showed histological and immunohistochemical (PCNA-ir) changes in rat kidney tissue. Otherwise, administration of REO pre or post-treatment with CrVI significantly restored most of the biochemical parameters in addition to improvement in kidney tissue architecture. Moreover, individual intake with REO exhibited an amendment in oxidative stress markers.

CONCLUSION

Conclusively, REO had a potential antioxidant capacity in ameliorating K₂Cr₂O₇-induced nephrotoxicity, especially in the protection group.

Anthropo-entomophagy: quantitatively chemical assessment of some edible arthropods, bought from an e-shop

Eating edible arthropods is not associated with rural life anymore. The emerging industry of edible arthropods is trying to change that. The best shopping spot to buy well-known edible arthropods is online today. Consumers can find numerous outlet options to buy edible arthropods from the Internet. With worldwide growing threats to food security, today, gastronomy, especially in western countries, is trying to develop a more positive view to arthropods' nutritional value. In this paper, non-crustacean arthropods (armor tail scorpion, black scorpion, black ant, flying termites, giant waterbug, June beetle, diving beetles, rhino beetles, silkworm pupae, sago worm, bamboo worm), bought from online edible insect market, were evaluated in terms of availability of some hazardous chemical. Energy Dispersive X-Ray Fluorescence (EDXRF) spectroscopy was used for determining the concentrations of heavy metals/metalloids in the total body of the arthropods. Concentration of the elements (Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Pb) were measured quantitatively in all samples. The results showed that the chemicals like Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb have highly been measured in the black scorpion, black ant, flying termites, giant waterbug, June beetle, sago worm, and bamboo worm.

Effects of Different Chromium Compounds on Hematology and Inflammatory Cytokines in Rats Fed High-Fat Diet

The aim of the study was to determine how a high-fat diet supplemented with various forms of chromium affects hematological and immune parameters of the blood of rats. The rats received a standard diet or a high-fat diet supplemented with chromium at 0.3 mg/kg body weight (BW) in the form of chromium(III) picolinate, chromium(III)-methionine or nano-sized chromium. Selected hematological parameters were determined in the blood of the rats, including total white blood cell (WBC) count, leukogram, red blood cell (RBC) count, hemoglobin level (HGB), hematocrit (HCT), platelet count (PLT) and platelet percentage (PCT), as well as immune parameters: levels of immunoglobulins A and E (IgA and IgE), interleukin-6 (IL-6), interleukin-2 (IL-2), and tumor necrosis factor α (TNF-α); activity of ceruloplasmin (Cp); and levels of caspase 3 and 8 (Casp3 and Casp8). Feeding rats a high-fat diet increased blood markers of induction of inflammation, ie pro-inflammatory cytokines IL-6 and TNF-α, and also significantly increased IgE. The diet had no effect on the blood count, except for an increase in the number of neutrophils. The chromium compounds tested, particularly Cr-Met and Cr-NPs, stimulated the immune system of the rats, as indicated by increased concentrations of IgA, IgE, IL-2, IL-6, TNF-α, and Cp. Given the increase in inflammatory mediators induced by chromium, it should not be used to mitigate the effects of a high-fat diet. Moreover, chromium picolinate and chromium nanoparticles were shown to increase the content of caspase 3 and 8 in the blood of rats, which indicates a pro-apoptotic effect. The effects of the use of chromium nanoparticles include reductions in the WBC count and in the thrombocyte count (leuko- and thrombopenia). Taking account these data the use of chromium as dietary supplement should be reconsidered.

The Double Face of Metals: The Intriguing Case of Chromium

Chromium (Cr) is a common element in the Earth’s crust. It may exist in different oxidation states, Cr(0), Cr(III) and Cr(VI), with Cr(III) and Cr(VI) being relatively stable and largely predominant. Chromium’s peculiarity is that its behavior relies on its valence state. Cr(III) is a trace element in humans and plays a major role in glucose and fat metabolism. The beneficial effects of Cr(III) in obesity and types 2 diabetes are known. It has been long considered an essential element, but now it has been reclassified as a nutritional supplement. On the other hand, Cr(VI) is a human carcinogen and exposure to it occurs both in occupational and environmental contexts. It induces also epigenetic effects on DNA, histone tails and microRNA; its toxicity seems to be related to its higher mobility in soil and swifter penetration through cell membranes than Cr(III). The microorganisms Acinetobacter sp. Cr1 and Pseudomonas sp. Cr13 have been suggested as a promising agent for bioremediation of Cr(VI). This review intends to underline the important role of Cr(III) for human health and the dangerousness of Cr(VI) as a toxic element. The dual and opposing roles of this metal make it particularly interesting. An overview of the recent literature is reported in support.

Incidence risk of bronchopneumonia in newborn calves associated with intrauterine diselementosis

Background and Aim

Macro- and micro-elements are required to ensure the normal course of biochemical processes in the development of an animal's body. Any excess, deficiency, or imbalance in chemical elements in an animal's body can cause the development of various latent or clinically expressed pathological conditions. Diselementosis in pregnant cows may lead to impaired embryo and fetal development, as well as reduced neonatal viability. The aim of this study was to analyze the content of macroelements and microelements in the blood serum of both calving cows and their calves to evaluate the relationship between indicators of mineral metabolism in the mother and newborn and to establish what role separate chemical elements play in making newborn calves more prone to bronchopneumonia.

Materials and Methods

The content of potassium (K), sodium (Na), iron (Fe), Copper (Cu), Zinc (Zn), Strontium (Sr), arsenic (As), nickel (Ni), cobalt (Co), chromium (Cr), molybdenum (Mo), and selenium (Se) in the blood serum of 33 pregnant cows between 239 and 262 days of gestation and their 33 1-day old calves was determined using the Shimadzu AA6300 (Japan) atomic adsorption spectrophotometer. Calcium (Ca) and magnesium (Mg) content was determined using ion-selective electrodes from the Olympus-400 analyzer (Beckman Coulter, USA). During the 1^st month of life, all calves in the sample set had some sort of respiratory diseases and seven of the calves had bronchopneumonia. Retrospectively, the samples of adult and newborn animals were divided into two groups each: Dams I - cows whose calves had uncomplicated bronchitis (n=26); Dams II - cows whose calves got bronchopneumonia (n=7); and Newborns I - calves with uncomplicated bronchitis (n=26); Newborns II - calves with bronchopneumonia (n=7).

Results

The content of Ca, Mg, K, Na, Mo, and Se in dams in both groups of cows was within the reference range; the concentrations of Fe and Ni were higher than the reference range; and the concentrations of Cu, Zn, As, Co, and Cr were lower than the reference range. There were no significant differences in elemental status between the Dams I and Dams II groups. In newborn calves, the concentration of Ca and Mo corresponded to the reference range; the concentrations of Mg, Fe, Co, and Ni in both groups exceeded the reference range; and the concentrations of Cu, Zn, As, Cr, and Se were lower than the reference range. Results highlighted that there was a tendency to decrease concentration of Fe, Mo, and Se and a significant increase in the Ni concentration in calves of the Newborns II group compared with calves of the Newborns I group. It was also found that Zn, Co, Cr, and Mo actively accumulated in the body of newborn animals while the transplacental transfer of Cu, As, and Sr was limited; and transfer of Se and Ni was regulated by concentration ratios in the blood of the mother and the fetus. The excessive concentrations of Ni and Fe in the blood serum of cows and calves and the imbalance in the ratio of elements Fe-Cu-Zn, Fe-Cu-Co negatively affected erythropoiesis, formation of the immune system, and antioxidant status of the fetus and newborn. These changes were considered to be risk factors for the development of bronchopneumonia in calves.

Conclusion

An excess of serum Fe and Ni and deficiency of Cu, Zn, As, Co, and Cr in cows during the gestation period can lead to similar impairments of the mineral status in newborn calves. At the systemic level, dyslementosis in combination with the influence of other adverse factors, can lead to an increased load on the respiratory and hematopoietic systems of calves during postnatal adaptation and can subsequently cause a decrease in the natural resistance of calves and development of bronchopneumonia.

X-ray structure of chromium(III)-containing transferrin: First structure of a physiological Cr(III)-binding protein

Transferrin, the Fe(III) transport protein in mammalian blood, has been suggested to also serve as a Cr(III) transporter and as part of a Cr(III) detoxification system; however, the structure of the metal-binding sites has never been fully elucidated with bound Cr(III). Chromium(III)-transferrin was crystallized in the presence of the synergistic anion malonate. In the crystals, the protein exists with a closed C-terminal lobe containing a Cr(III) ion and an open, unoccupied N-terminal lobe. The overall structure and the metal ion environments are extremely similar to those of Fe(III)- and Ti(IV)-containing transferrin crystallized under comparable conditions. The octahedral coordination about the Cr(III) is comprised of four ligands provided by the protein (two tyrosine residues, a histidine residue, and an aspartate residue) and a chelating malonate anion. This represents the first crystal structure of a Cr(III)-containing protein that binds Cr(III) as part of its physiological function.

Potential use of chromium to combat thermal stress in animals: A review

Heat stress (HS) has adverse effects on the body: it decreases body weight, feed efficiency, feed intake, carcass quality, and nutrient digestibility. Chromium (Cr) can prevent lipid peroxidation induced by HS through its strong antioxidant activities, especially when it is added to the poultry diet. It improves the action of insulin and nutrient metabolism (of lipids, proteins, nucleic acid, and carbohydrates) through activation of enzymes associated with such pathways. The results of the studies on Cr added to diets with concentrations of 0.05 mg Cr/kg of Cr-methionine led to improved feed efficiency and DM intake by cows and Holstein dairy calves exposed to high environmental temperatures. Moreover, calves that received Cr at levels of 0.05 mg/kg of body weight tended to have higher serum concentrations of glucose and higher ratios of insulin to glucose. In heat-stressed pigs, Cr addition (200 ppb) increased blood neutrophils by about 37%. Several studies have asserted that Cr can inhibit inflammation in lactating cows by promoting the release of Hsp72, assisting production of IL-10 and inhibiting degradation of IκBα in HS conditions. In addition, Cr supplementation was observed to possibly have positive impacts on both cell-mediated and humeral immunity in heat-stressed buffalo calves. Studies over the last two decades have shown with certainty that chromium supplementation has an impact on many variables in chickens. Moreover, Cr is believed to increase insulin action in insulin-sensitive tissues (i.e., adipose and muscles), resulting in increased farm animal productivity through the improvement of feed intake, growth rate, carcass quality, reproductive parameters and immune functions.

Chromium(III) Glycinate Complex Supplementation Improves the Blood Glucose Level and Attenuates the Tissular Copper to Zinc Ratio in Rats with Mild Hyperglycaemia

The aim of the study was to evaluate the hypoglycaemic potential of supplementary Cr in the form of chromium(III) glycinate (CrGly) in the diabetic model of rats. The experiment was conducted on 40 male Wistar rats, of which 30 were made diabetic by injection of a single dose of streptozotocin (55 mg/kg b.m.), while the remaining 10 rats served as the healthy control. After inducing hyperglycaemia, 2 groups of diabetic rats (10 rats each) were supplemented with Cr either as CrGly or chromium(III) picolinate (CrPic) given orally at a dose of 10 mg/kg diet (about 0.75 mg Cr/kg b.m.) with adequate AIN-93M diet for 7 weeks. At the termination of experiment, all animals were sacrificed to collect blood and internal organs for biochemical assays. Blood biochemical indices and tissular trace element contents (Fe, Zn, Cu, Cr) were measured and compared with the values of the untreated groups. It was found that CrGly significantly decreased blood glucose, total cholesterol, HDL cholesterol and triacylglycerol levels more efficiently than CrPic. Furthermore, both Cr compounds normalized disturbed the serum, renal and cardiac molar Cu/Zn ratio, as well as restored the kidney Zn and Cu levels in rats with hyperglycaemia. Supplementary Cr did not increase the tissular Cr levels in diabetic rats. The study confirmed the hypoglycaemic potential of CrGly in the diabetic model of rats.

Potential roles of chromium on inflammatory biomarkers in diabetes: A Systematic

Diabetes, as a low-grade chronic inflammatory disease, causes disruption in proper function of immune and metabolic system. Chromium is an important element required for normal lipid and glucose metabolism. Chromium deficiency is correlated with elevation in cardiometabolic risk, which results from increased inflammation. This systematic review was conducted to discover the potential roles of chromium on inflammatory biomarkers. Eligible studies were all in vitro, animal and human studies published in English-language journals from inception until October 2018. PubMed, Scopus, Embase, ProQuest and Google Scholar databases were searched to fined interventional studies from the effects of chromium on inflammatory biomarkers such as tumour necrosis factor a (TNF-a), C-reactive protein (CRP), interleukins, monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and adipocytokines in hyperglycaemia and diabetes. Out of 647 articles found in the search, only 14 articles were eligible for analysis, three in vitro studies, eight animal studies and three human studies. Twelve of the 14 studies included in this review, chromium significantly decreased inflammatory factors. The findings of this review indicate, based on in vitro and in vivo studies, that chromium might have potential anti-inflammatory properties, but some of the studies did not show anti-inflammatory effects for chromium (two studies). There are only three studies in humans with controversial results. Therefore, more consistent randomized double-blind controlled trials are needed to reach relevant clinical recommendations, as well as to determine the precise mechanism, of chromium on inflammation in diabetes.

Influence of chromium citrate on oxidative stress in the tissues of muscle and kidney of rats with experimentally induced diabetes

Chromium is one of the important trace elements that is essential for carbohydrate, protein and lipid metabolism. Chromium improves glucose metabolism and reduces insulin resistance due to increased insulin sensitivity. Therefore, it is important to consider the use of chromium citrate as a nutritional supplement with potential hypoglycemic and hypolipidemic effects. In this research work, we investigated the activity of the antioxidant system and the level of lipid hydroperoxides in the tissues of skeletal muscles and kidneys of experimental diabetic rats and for rats which received in their daily diet chromium citrate in the amounts 0.1 and 0.2 μg/mL of water. We induced the experimental model of diabetes by intraperitoneal injection of alloxan in the amount 150 mg/kg of body weight of the animals. We monitored glucose levels by measuring daily glucose levels with a portable glucose meter. For research, we selected animals with a glucose level > 11.1 mmol/L. We monitored the body weight of rats. On the 40th day of the study, we withdrew the animals from the experiment by decapitation. We selected the tissue for research, namely skeletal muscles and kidneys. In samples of the tissue homogenates, we measured the activity of antioxidant enzymes and the content of lipid peroxide oxidation products. As a result of our research, we found that the products of lipid peroxide oxidation and glutathione peroxidase activity increased in skeletal muscle of animals with diabetes mellitus. The activity of glutathione reductase, catalase, superoxide dismutase, and the content of reduced glutathione decreased at the same time. In the kidneys of diabetic rats, the activity of glutathione peroxidase, glutathione reductase, catalase and content of lipid hydroperoxides increased but the activity of superoxide dismutase and the content of reduced glutathione decreased. The addition of chromium citrate to the diet of animals in amounts 0.1 and 0.2 μg/mL led to the suppression of oxidative stress. The activity of catalase, glutathione peroxidase and the content of lipid hydroperoxides, TBA-positive substances decreased. Also, the activity of superoxide dismutase increased with the addition of chromium citrate. These results indicate normalization of antioxidant defense in the skeletal muscle and kidneys of experimental rats with experimental diabetes given chromium citrate in the amount 0.1 mg/mL of water.

Metalloproteins in the Biology of Heterocysts

Cyanobacteria are photoautotrophic microorganisms present in almost all ecologically niches on Earth. They exist as single-cell or filamentous forms and the latter often contain specialized cells for N₂ fixation known as heterocysts. Heterocysts arise from photosynthetic active vegetative cells by multiple morphological and physiological rearrangements including the absence of O₂ evolution and CO₂ fixation. The key function of this cell type is carried out by the metalloprotein complex known as nitrogenase. Additionally, many other important processes in heterocysts also depend on metalloproteins. This leads to a high metal demand exceeding the one of other bacteria in content and concentration during heterocyst development and in mature heterocysts. This review provides an overview on the current knowledge of the transition metals and metalloproteins required by heterocysts in heterocyst-forming cyanobacteria. It discusses the molecular, physiological, and physicochemical properties of metalloproteins involved in N₂ fixation, H₂ metabolism, electron transport chains, oxidative stress management, storage, energy metabolism, and metabolic networks in the diazotrophic filament. This provides a detailed and comprehensive picture on the heterocyst demands for Fe, Cu, Mo, Ni, Mn, V, and Zn as cofactors for metalloproteins and highlights the importance of such metalloproteins for the biology of cyanobacterial heterocysts.

Boron, Chromium, Manganese, and Nickel in Agricultural Animal Production

This paper provides an overview of research that has been conducted with manganese (Mn), chromium (Cr), nickel (Ni), and boron (B) in poultry, swine, and ruminants. Manganese is an essential trace mineral that functions as an enzyme component and enzyme activator. A deficiency of Mn results in a variety of bone abnormalities, and Mn deficiency signs have been observed under practical conditions in poultry and cattle. Chromium can potentiate the action of insulin, but whether Cr is an essential trace mineral is controversial. Insulin sensitivity has been enhanced by Cr in cattle, swine, and broilers. Responses to Cr supplementation have been variable. Production responses to Cr supplementation have been most consistent in animals exposed to various stressors (heat, cold, weaning, etc). The legality of supplementing Cr to animal diets varies among countries, Cr sources, and animal species. A specific biochemical function for Ni and B has not been identified in mammals. Signs of Ni deficiency have been produced experimentally in a number of animal species. Nickel may affect rumen microbial fermentation in ruminants, as Ni is a component of bacterial urease and cofactor F₄₃₀ in methanogenic bacteria. There is little evidence that dietary Ni limits animal production under practical conditions. Beneficial effects of B supplementation on growth and bone strength have been seen in poultry and swine, but results have been variable.

Dietary Supplementation with Chromium Picolinate Influences Serum Glucose and Immune Response of Brown-Egg Laying Hens

To investigate the effect of chromium picolinate (CrPic) on egg production performance, egg quality, blood indices, and immune function of laying hens, 270 23-week-old Beijing Red brown-egg laying hens were randomly assigned to one of three treatments with six replicates of 15 birds per replicate for each treatment in a completely randomized design. Laying hens were fed a Cr-unsupplemented corn-soybean meal basal diet (control, containing 0.45 mg Cr/kg by analysis) or the basal diet supplemented with 0.4 or 0.6 mg Cr/kg from CrPic for 10 weeks. Laying hens fed diets supplemented with CrPic had a lower (P < 0.05) serum glucose (GLU) concentration and higher (P < 0.03) serum antibody titer against Newcastle disease than those fed the control diet at 33 weeks of age. However, supplemental CrPic had no effect (P > 0.05) on egg production and egg quality of brown-egg laying hens from 24 to 33 weeks of age. The results from this study indicated that supplemental CrPic decreased serum GLU and enhanced the immune function of brown-egg laying hens.

The effects of plasma chromium on lipid profile, glucose metabolism and cardiovascular risk in type 2 diabetes mellitus. A case - control study

BACKGROUND

The study was aimed at determining the effect of plasma chromium concentration on the metabolism of glucose, and lipids and their subsequent cardiovascular risk in patients with type 2 diabetes in the Bolgatanga district of Ghana.

MATERIAL AND METHODS

Fasting blood glucose and lipids profile were determined by enzymatic assay using the BT 5000® Random Access Chemistry Analyzer. Fasting serum insulin and High sensitive C-reactive protein were determined by ELISA, a solid phase direct sandwich immunoassay method. HOMA-IR, which is based on fasting blood sample for insulin and glucose concentrations measured in a single blood sample, was used to calculate insulin resistance. Plasma chromium was measured using an atomic Absorption Spectrometer.

RESULTS

Patientswith diabeteshad significantly (p<0.0001) increased LDL, TC, TG, VLDL, insulin, CRP and HOMAIR and a significantly reduced plasma chromium (p<0.0001) (0.53± 0.02μg/l and 0.11±0.01μg/l control and case respectively). Low Cr (p ≤0.001) was associated with high blood pressure, obesity and lipid dysregulation. Plasma Cr significantly correlated negatively with blood pressure and LDL.

CONCLUSION

Lower plasma Cr level was associated with hyperglycaemia, hyperinsulinemia, hypertension, insulin resistance and high inflammation marker HsCRP.

Nigella sativa Oil and Chromium Picolinate Ameliorate Fructose-Induced Hyperinsulinemia by Enhancing Insulin Signaling and Suppressing Insulin-Degrading Enzyme in Male Rats

In vivo and in vitro studies suggested that chromium enhances insulin sensitivity by promoting insulin receptor signaling. However, its effect on insulin clearance has not been yet identified. Nigella sativa, a widely used spice, possesses an antidiabetic activity. We, therefore, hypothesized that chromium picolinate may alter insulin clearance by modulating insulin-degrading enzyme (IDE) in insulin-resistant rats. We evaluated also the effect of Nigella sativa oil on insulin signaling and degradation with respect to chromium picolinate. To assess these hypotheses, insulin resistance was induced in 30 male Wistar albino rats through daily oral administration of high-fructose water (HFW, 20% w/v) for 45 days. These rats were then divided into three groups (n = 10/group). They were given either no treatment (control group) or Nigella sativa oil (500 mg/kg bw/day) or chromium picoloinate (200 μg/kg bw/day) orally along with HFW (20% w/v) for 45 days. Nigella sativa oil or chromium picolinate concurrent administration with HFW significantly decreased body weight, serum lipids, glucagon, insulin resistance, and hepatic IDE level but increased its mRNA expression and insulin receptor phosphorlyation as well as high-density lipoprotein cholesterol (HDL-C) level as compared to control group values, suggesting their potential as modulators for insulin signaling and clearance. However, Nigella sativa oil exerted better improvement in feeding efficacy ratio as well as the levels of glucagon, insulin, insulin resistance, hepatic IDE level and insulin receptor phosphorylation than chromium picolinate, suggesting its greater insulin sensitizing capacity. Our data, for the first time, prove that Nigella sativa oil and chromium picolinate monotherapy can reduce fructose-induced insulin resistance by reduction of hepatic IDE protein and activation of insulin receptor signaling.

Invited review: Mineral absorption mechanisms, mineral interactions that affect acid-base and antioxidant status, and diet considerations to improve mineral status

Several minerals are required for life to exist. In animals, 7 elements (Ca, P, Mg, Na, K, Cl, and S) are required to be present in the diet in fairly large amounts (grams to tens of grams each day for the dairy cow) and are termed macrominerals. Several other elements are termed microminerals or trace minerals because they are required in much smaller amounts (milligrams to micrograms each day). In most cases the mineral in the diet must be absorbed across the gastrointestinal mucosa and enter the blood if it is to be of value to the animal. The bulk of this review discusses the paracellular and transcellular mechanisms used by the gastrointestinal tract to absorb each of the various minerals needed. Unfortunately, particularly in ruminants, interactions between minerals and other substances within the diet can occur within the digestive tract that impair mineral absorption. The attributes of organic or chelated minerals that might permit diet minerals to circumvent factors that inhibit absorption of more traditional inorganic forms of these minerals are discussed. Once absorbed, minerals are used in many ways. One focus of this review is the effect macrominerals have on the acid-base status of the animal. Manipulation of dietary cation and anion content is commonly used as a tool in the dry period and during lactation to improve performance. A section on how the strong ion theory can be used to understand these effects is included. Many microminerals play a role in the body as cofactors of enzymes involved in controlling free radicals within the body and are vital to antioxidant capabilities. Those same minerals, when consumed in excess, can become pro-oxidants in the body, generating destructive free radicals. Complex interactions between minerals can compromise the effectiveness of a diet in promoting health and productivity of the cow. The objective of this review is to provide insight into some of these mechanisms.

New Evidence against Chromium as an Essential Trace Element

Nearly 60 y ago, chromium, as the trivalent ion, was proposed to be an essential element, but the results of new studies indicate that chromium currently can only be considered pharmacologically active and not an essential element. Regardless, articles still continue to appear in the literature claiming chromium is an essential element. Chromium has been marketed as an agent to reduce body mass and develop muscle; however, such marketing claims are no longer allowed in the United States because these claims, similar to claims of essential status, are not supported by experiments. Trivalent chromium has also been proposed as a therapeutic agent to increase insulin sensitivity and affect lipid metabolism. Although effective in certain rodent models, beneficial effects in humans have not been unequivocally established. Molecular mechanisms have been proposed for the beneficial effects but have not been definitively shown to occur in animals.

Isoproterenol exacerbates hyperglycemia and modulates chromium distribution in mice fed with a high fat diet

BACKGROUND AND PURPOSE

Isoproterenol (ISO), a nonselective β-adrenoceptor agonist for treating bradycardia and asthma, has been proposed to raise blood glucose level. Little is known regarding the relationship between ISO treatment, the induced chromium (Cr) redistribution, and changes in glucose metabolism. We aimed to characterize the effects of a single dose of ISO on glucose homeostasis and Cr level changes in an obesity mouse model.

METHODS

Mice (C57BL6/j strain) were first fed for a continuous period of 12 weeks with either a high fat diet (HFD), to develop an obesity animal model, or a standard diet (SD), to develop a lean animal model as controls. These groups were each separated into two subgroups to receive either a single dose of ISO or saline (control). We measured in vivo their metabolic parameters, fasting glucose level, area under the curve (AUC) for glucose level time profile, insulin level time profile, insulin sensitivity index, and chromium distribution.

RESULTS

After a single dose of ISO, the SD-fed mice had slightly higher blood glucose levels compared with the SD controls, when the level was measured 30 and 60min after injection. By contrast, the ISO-treated HFD-fed mice had significantly higher blood glucose levels and AUC during the entire 120min following one administration compared with the HFD control group. Additionally, they had a substantially lower HOMA-IR index, whereas insulin levels remained unchanged. The Cr level in their bones and liver was decreased, and loss of Cr through urinary excretion was elevated.

CONCLUSION

The results demonstrated that ISO exacerbated hyperglycemic syndrome in the obesity animal model. ISO induced a net negative Cr balance as a result of increased urinary excretion, leading to Cr mobilization that was not desirable to overcome the hyperglycemia.

Melatonin protects against chromium (VI) induced hepatic oxidative stress and toxicity: Duration dependent study with realistic dosage

The present study was undertaken to assess the degree of oxidative stress and toxic effects induced by chromium on hepatic tissue in male Wistar rats exposed to a realistic dosage of Cr(VI) (20 mg/kg/b.w./day) through drinking water, based on the levels of these metals found in the environment, for a duration of 15, 30 and 60 days. The protective effect of melatonin (10 mg/kg) was also studied by simultaneous administration with the metal. Levels of enzymatic and non-enzymatic antioxidants as well as lipid peroxidation were assessed. There was a significant decrease in enzymatic as well as non-enzymatic antioxidants and an increase in the lipid peroxidation level, which were prevented and maintained at near-normal levels by the administration of melatonin in all treatment periods. Metal accumulation was maximal at 15 days, with gradual decreases till 60 days. Histopathological observations also demonstrated the fact that Cr (VI) exposure leads to cytological lesions in the hepatic tissue promoting cellular necrotic/apoptotic changes, while melatonin was able to counteract insults induced by Cr (VI) at all treatment periods. It also prevented alterations in insulin and glucose levels. Overall, the present study suggests a duration-dependent effect of Cr on hepatic oxidative stress and cytotoxicity and shows the potent activity of melatonin in preventing the negative effects of Cr (VI).

N-Acetyl-L-Cysteine Protects Liver and Kidney Against Chromium(VI)-Induced Oxidative Stress in Mice

Acute hexavalent chromium [Cr(VI)] compound exposure may lead to hepatotoxic and nephrotoxic effects. Cr(VI) reduction may generate reactive intermediates and radicals which might be associated with damage. We investigated effects of N-acetyl-l-cysteine (NAC) pre- or post-treatment on oxidative stress and accumulation of Cr in liver and kidney of Cr(VI)-exposed mice. Intraperitoneal potassium dichromate injection (20 mg Cr/kg) caused a significant elevation of lipid peroxidation in both tissues as compared to control (p < 0.05). Significant decreases in non-protein sulfhydryl (NPSH) level, as well as enzyme activities of catalase (CAT) and superoxide dismutase (SOD) along with significant accumulation of Cr in the tissues (p < 0.05) were of note. NAC pre-treatment (200 mg/kg, ip) provided a noticeable alleviation of lipid peroxidation (p < 0.05) in both tissues, whereas post-treatment exerted significant effect only in kidney. Similarly, Cr(VI)-induced NPSH decline was restored by NAC pre-treatment in both tissues (p < 0.05); however, NAC post-treatment could only replenish NPSH in liver (p < 0.05). Regarding enzyme activities, in liver tissue NAC pre-treatment provided significant restoration on Cr(VI)-induced CAT inhibition (p < 0.05), while SOD enzyme activity was regulated to some extent. In kidney, SOD activity was efficiently restored by both treatments (p < 0.05), whereas CAT enzyme alteration could not be totally relieved. Additionally, NAC pre-treatment in both tissues and post-treatment in liver exerted significant tissue Cr level decreases (p < 0.05). Overall, especially NAC pre-treatment seems to provide beneficial effects in regulating pro-oxidant/antioxidant balance and Cr accumulation caused by Cr(VI) in liver and kidney. This finding may be due to several mechanisms including extracellular reduction or chelation of Cr(VI) by readily available NAC.

Multielemental speciation analysis by advanced hyphenated technique - HPLC/ICP-MS: A review

Speciation analysis has become an invaluable tool in human health risk assessment, environmental monitoring or food quality control. Another step is to develop reliable multielemental speciation methodologies, to reduce costs, waste and time needed for the analysis. Separation and detection of species of several elements in a single analytical run can be accomplished by high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS). Our review assembles articles concerning multielemental speciation determination of: As, Se, Cr, Sb, I, Br, Pb, Hg, V, Mo, Te, Tl, Cd and W in environmental, biological, food and clinical samples analyzed with HPLC/ICP-MS. It addresses the procedures in terms of following issues: sample collection and pretreatment, selection of optimal conditions for elements species separation by HPLC and determination using ICP-MS as well as metrological approach. The presented work is the first review article concerning multielemental speciation analysis by advanced hyphenated technique HPLC/ICP-MS.

Tissue accumulation and urinary excretion of Cr in chromium picolinate (CrPic)-supplemented lambs

Chromium (Cr) concentrations in liver, kidney, spleen, heart, lymph node, skeletal muscle, bone, testis and urine of lambs were measured to trace the biodistribution and bioaccumulation of Cr after oral supplementation with chromium picolinate (CrPic). Twenty-four Santa Inês lambs were treated with four different concentrations of CrPic: placebo, 0.250, 0.375 and 0.500 mg of CrPic/animal/day for 84 days. The basal diet consisted of Panicum maximum cv Massai hay and concentrate. Cr concentrations were measured by ICP-MS measuring (52)Cr as collected mass. There was a positive linear relationship between dose administered and the accumulation of Cr in the heart, lungs and testis. Urinary excretion of Cr occurred in a time and dose-dependent manner, so the longer or more dietary Cr provided, the greater excretion of the element. As some non-carcass components (such as lungs or heart) are added to bone and visceral meal to feed animals, there is a risk of bioaccumulation and biomagnification due to Cr offered as CrPic in the diet.

Effect of Chromium Supplementation on Element Distribution in a Mouse Model of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder and one of the most common causes of anovulatory infertility. In addition, insulin resistance is commonly associated with PCOS and contributed to pathophysiology connected to dietary minerals including chromium (Cr), copper (Cu), iron (Fe), and zinc (Zn). The aims of this study were to explore whether PCOS in mice alters levels of these elements and determine if Cr supplementation resolves changes. Twenty-four female BALB/c mice were divided into three groups of eight mice [normal control (NC), PCOS+placebo milk (PP), and PCOS+Cr-containing milk (PCr)]. Each group received a high-fat diet for 4 weeks. Our results show significantly higher levels of dehydroepiandrosterone (DHEA) (p<0.001), fasting glucose (p<0.05), and fasting insulin (p<0.05) in the PP group compared with both NC and PCr group. However, Cr levels were significantly lower in muscle, bone, and serum in the PP group (p<0.05) compared with NC and PCr groups. In liver, bone, and serum, Fe levels were significantly higher in the PP group compared with the NC group (p<0.05). In addition, we found significant correlations between Cu/Zn ratio and fasting insulin in all mice (r=0.61; p=0.002). Given that significant research shows that Cr supplementation improves fasting glucose, fasting insulin, and metal metabolism disorders for PCOS mice, our data suggest that trace element levels can serve as biomarkers to prescribe therapeutic supplementation to maintain a healthy metabolic balance and treat disease conditions.