Effects of chromium supplementation on glycemic control in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: We aimed to investigate the effect of chromium supplementation on glycemic control indices in patients with type 2 diabetes (T2DM). METHODS: Randomized controlled trials examining the effect of chromium supplementation on glycemic control indices and published before February 2020 were detected by searching online databases, including PubMed, Scopus, Embase, Web of sciences and The Cochrane Library, using a combination of suitable keywords. Mean change and standard deviation (SD) of the outcome measures were used to estimate the mean difference between the supplementation group and the control group at follow-up. RESULTS: Twenty-eight studies reported fasting plasma glucose (FPG), insulin, hemoglobin A1C (HbA1C) and homeostatic model assessment for insulin resistance (HOMA-IR) as an outcome measure. Results revealed significant reduction in FPG (weighted mean difference (WMD): -19.00 mg/dl, 95% CI: -36.15, -1.85, P = 0.030; I2: 99.8%, p < 0.001), insulin level (WMD: -12.35 pmol/l, 95% CI: -17.86, -6.83, P < 0.001), HbA1C (WMD: -0.71 %, 95% CI: -1.19, -0.23, P = 0.004) and HOMA-IR (WMD: -1.53, 95% CI: -2.35, -0.72, P < 0.001; I2: 89.9%, p < 0.001) after chromium supplementation. CONCLUSION: The results of the current meta-analysis study might support the use of chromium supplementation for the improvement of glycemic control indices in T2DM patients.

Germinação de Phaseolus aureus contaminados com diferentes fontes de cromo (VI) / Germination of Phaseolus aureus contaminated with different sources of chromium (VI)

O excesso de Cr nas plantas pode provocar inibição no crescimento das plantas, clorose nas folhas, desequilíbrio nutricional e alteração na germinação das sementes, sendo também altamente tóxico para humanos. Objetivou-se avaliar a germinação de sementes de feijão submetidas a diferentes fontes de Cr, em câmara germinadora durante 9 dias. As fontes de Cr utilizadas: cromato de potássio e dicromato de potássio, em 128 subamostras em soluções de concentrações crescentes de Cr (0, 5,10, 20, 45, 90, 200 e 400 mg L-1). Realizou contagem de sementes normais, anormais e mortas. Conclui-se que sementes de feijão submetidas ao dicromato de potássio germinam 47,5% em média, sem efeitos prejudiciais ao seu desenvolvimento, com apenas 0,87% de sementes anormais e 1,6% em média de sementes mortas, ambas com tolerância de até 400 mg L-1.

Cancer mortality and exposure to nickel and chromium compounds in a cohort of Italian electroplaters.

BACKGROUND: Nickel and chromium-VI compounds are carcinogens for lung cancer, although it is still debated if there is an increased risk at low levels of exposure and for other cancers. METHODS: In a cohort of 2991 Italian electroplaters, a proportion of whom were exposed to low levels of nickel and/or chromium, cumulative exposure to their compounds was obtained by multiplying average concentrations of the metals in each electroplating tank by duration of employment in the company. The association of exposure to compounds with mortality was assessed by multivariable Cox models. RESULTS: No cancer site was associated with chromium exposure controlling for nickel, whereas exposure to nickel significantly increased mortality from lung, rectal, and kidney cancers, even after adjusting for exposure to chromium. CONCLUSIONS: Study results suggest that exposure to nickel compounds may increase the risk of lung cancer even below its occupational exposure limit and indicate possible associations with other cancer sites.

Chromium(III), chromium(VI) and cobalt release from leathers produced in Nicaragua.

BACKGROUND: Leather exposure has been associated with chromium (Cr) and cobalt (Co) contact dermatitis. Cr(VI) in leather is now restricted to <3 mg/kg in the EU. Cr(III) is not restricted. OBJECTIVES: To analyse 29 differently coloured Cr-tanned leather samples from two Nicaraguan tanneries, and to compare their release of Cr, Cr(VI) and Co with that of leathers produced in Europe. METHODS: Cr, Cr(VI) and Co were extracted in phosphate buffer for 3 hours at 25°C according to EN ISO 17075. Atomic absorption spectroscopy and spectrophotometry were used for detection of the metals in phosphate buffer. RESULTS: There was no difference in total Cr or Cr(VI) release between European and Nicaraguan leathers. There was no association between Cr(VI) and total Cr release. Co was released primarily from leathers of one tannery. Cr(III) was released in significantly higher amounts than Cr(VI). CONCLUSIONS: Future investigations and regulations should focus on Cr(III) and Co as well as on Cr(VI).

Differential expression of the PAL gene family in rice seedlings exposed to chromium by microarray analysis.

Phenylalanine ammonia-lyase (PAL) is one of the principle enzymes involved in plant's secondary metabolism. Expression of individual isogene from the PAL gene family is variable with species of plants in responses to different stresses. In this study, transcriptome analysis of the PAL gene family in rice seedlings exposed to potassium chromate Cr(VI) or chromium nitrate Cr(III) was conducted using Agilent 44K rice microarray and real-time quantitative RT-PCR. Uptake and accumulation of both Cr species by rice seedlings and their effect on PAL activity were also determined. Three days of Cr exposure led to significant accumulation of Cr in plant tissues, but majority being in roots rather than shoots. Changes of PAL activities in rice tissues were evident from both Cr treatments. Individual isogene from the rice PAL gene family was expressed differentially in response to both Cr variants. Comparing gene expression between two Cr treatments, only osPAL2 and osPAL4 genes were expressed in similar patterns. Also, gene expression pattern was inconsistent in both plant tissues. Results indicated that expression of individual isoform from the rice PAL gene family is tissue, and stimulus specific under different Cr exposure, suggesting their different detoxification strategies for decreasing or eliminating Cr stresses.

Chromium(III) release from chromium-tanned leather elicits allergic contact dermatitis: a use test study.

BACKGROUND: Chromium (Cr) is a common skin sensitizer. The use of Cr(VI) in leather is restricted in the EU, but that of Cr(III) is not. OBJECTIVES: To assess whether prolonged exposure to Cr-tanned leather with mainly Cr(III) release may elicit allergic contact dermatitis in Cr-allergic individuals. METHOD: Ten Cr-allergic subjects and 22 controls were patch tested with serial dilutions of Cr(III) and Cr(VI), and with leather samples. They then conducted a use test with a Cr-tanned and a Cr-free leather bracelet over a period of 3 weeks, for 12 h per day. Cr deposited on the skin from the bracelets was measured in the controls, and the diphenylcarbazide test for Cr(VI) and extraction tests for Cr(III) and Cr(VI) were conducted for the different leathers. RESULTS: Four of 10 Cr-allergic subjects developed positive reactions to the Cr-tanned bracelet within 7-21 days, whereas only 1 of 10 had a positive patch test reaction to this leather. Cr released from the Cr-tanned leather was most probably entirely Cr(III), with a quantifiable amount being deposited on the skin. CONCLUSIONS: This study strongly suggests that prolonged and repeated exposure to Cr-tanned leather with mainly Cr(III) release is capable of eliciting allergic contact dermatitis in Cr-allergic individuals.

Debunking the Myth of Wool Allergy: Reviewing the Evidence for Immune and Non-immune Cutaneous Reactions.

Although wool is commonly believed to cause irritant (non-immune) and hypersensitivity (immune) cutaneous reactions, the evidence basis for this belief and its validity for modern garments have not been critically examined. Publications from the last 100 years, using MEDLINE and Google Scholar, were analysed for evidence that wool causes cutaneous reactions, both immune-mediated (atopic dermatitis exacerbation, contact urticaria, allergic contact dermatitis) and non-immune-mediated (irritant contact dermatitis, itch). Secondary aims of this paper were to examine evidence that lanolin and textile-processing additives (formaldehyde, chromium) cause cutaneous reactions in the context of modern wool-processing techniques. Current evidence does not suggest that wool-fibre is a cutaneous allergen. Furthermore, contact allergy from lanolin, chromium and formaldehyde is highly unlikely with modern wool garments. Cutaneous irritation from wool relates to high fibre diameters (≥ 30-32 µm). Superfine and ultrafine Merino wool do not activate sufficient c-fibres to cause itch, are well tolerated and may benefit eczema management.

Chromium-induced diffuse dermatitis with lymph node involvement resulting from Langerhans cell histiocytosis after metal-on-metal hip resurfacing.

Total hip arthroplasty (THA) is a highly effective surgical treatment for severe joint involvement. However, due to the release of metal ions in the blood, the patients who undergo hip replacement with metal-on-metal (MOM) bearings may develop signs of allergic skin disease. We report a case of a 60-year-old man who had received MOM hip resurfacing 5 years earlier for osteoarthritis. He presented with a 3-year history of diffuse dermatitis that did not respond to antihistamines and corticosteroids and also had elevated serum levels of chromium and cobalt. A patch test revealed chromium-sulfate hypersensitivity. A skin biopsy showed nonspecific perivascular lymphocytic infiltrate associated with histiocytes. A biopsy of an inguinal lymph node demonstrated large aggregates of Langerhans cells, suggesting type IV delayed-type hypersensitivity. The prosthesis was replaced using ceramic-on-ceramic bearings and the dermatitis resolved after 3 months. The lymph nodes decreased in volume and the serum chromium levels normalized within 24 months of revision surgery. The high levels of serum ions associated with the metal debris from MOM-THAs may induce sensitization and type IV hypersensitivity reactions. Replacing the prosthesis using alternative coupling surfaces is the only approach that has the capacity to resolve these symptoms. Physicians who are not familiar with this issue may misdiagnose systemic symptoms and provide inadequate treatment.

miR-375 and miR-30d in the effect of chromium-containing Chinese medicine moderating glucose metabolism.

In China, TianMai Xiaoke tablet (TM) is used to treat type 2 diabetes. However, the exact mechanism of TM is not clear. This study is to investigate the effect of TM on glucose metabolism in diabetic rats and to identify whether TM takes a direct action through microRNAs on islet. Rats were divided into control group, diabetic group, low dose of TM group (TML), and high dose of TM group (TMH). Pancreas samples were analyzed using microRNA array and Q-PCR. Eight-week treatment with TM significantly decreased fasting blood glucose. The blood glucose was significantly reduced in TM-treated groups before and after oral glucose administration. Fasting insulin and HOMA-IR were suppressed in TM-treated groups. miR-448, let-7b, miR-540, miR-296, miR-880, miR-200a, miR-500, miR-10b, miR-336, miR-30d, miR-208, let-7e, miR-142-5p, miR-874, miR-375, miR-879, miR-501, and miR-188 were upregulated, while miR-301b, miR-134, and miR-652 were downregulated in TMH group. Through target gene analysis and real-time PCR verification, we found that these miRNAs, especially miR-375 and miR-30d, can stimulate insulin secretion in islet. Our data suggest that TM can improve blood glucose in diabetic rats which involved increasing the expression of miR-375 and miR-30d to activate insulin synthesis in islet.

Chromium: is it essential, pharmacologically relevant, or toxic?

Over fifty years ago, the element chromium (as the trivalent ion) was proposed to be an essential element for mammals with a role in maintaining proper carbohydrate and lipid metabolism. Evidence for an essential role came from dietary studies with rodents, studies on the effects of chromium on subjects on total parenteral nutrition, and studies of the absorption and transport of chromium. Over the next several decades, chromium-containing nutritional supplements became so popular for weight loss and muscle development that sales were second only to calcium among mineral supplements. However, the failure to identify the responsible biomolecules(s) that bind chromium(III) and their mode of action, particularly a postulated species named glucose tolerance factor or GTF, resulted in the status of chromium being questioned in recent years, such that the question of its being essential needs to be formally readdressed. At the same time as chromium(III)'s popularity as a nutritional supplement was growing, concerns over its safety appeared. While chromium has been conclusively shown not to have beneficial effects on body mass or composition and should be removed from the list of essential trace elements, chromium(III) compounds are generally nontoxic and have beneficial pharmacological effects in rodents models of insulin insensitivity, although human studies have not conclusively shown any beneficial effects. Mechanisms have been proposed for these pharmacological effects, but all suffer from a lack of consistent supporting evidence.

The efficacy of chromium as a growth enhancer for mirror carp (Cyprinus carpio L): an integrated study using biochemical, genetic, and histological responses.

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

Renal impairment caused by chronic occupational chromate exposure.

PURPOSE: To determine the nephritic toxicity of chromate after chronic occupational exposure. METHODS: The environmental contamination was assessed by measuring the chromium (Cr) in 8-h airborne sampler. The integrated level of Cr was determined by Cr concentrations in the whole blood (WB-Cr) and the urine (U-Cr). The renal glomerular and tubule impairment was evaluated by determination of cystatin C (Cys-C) in the serum and microalbumin (mALB), urinary beta(2)-microglobulin (ß(2)M), N-acetyl-beta-D-glucosaminidase (NAG) activity in the urine. RESULTS: The mean occupational exposure time to Cr was 12.86 years with average daily air level of 27.13 µg/m(3) comparing to 0.11 µg/m(3) of the background level. The WB-Cr and U-Cr were 23.49 µg/L and 17.41 µg/g creatinine (Cre), respectively in the chromate-exposed workers comparing to 3.32 µg/L and 1.52 µg/g Cre in the controls. The serum Cys-C and urinary mALB were significantly increased in the chromate-exposed workers. Exposure to Cr seems to induce an enhanced level of urinary NAG activity and ß(2)M concentration. The increased serum Cys-C concentration was positively correlated with the level of serum Cre. The U-Cr was positively correlated to the concentrations of urinary mALB, ß(2)M, and the activity of NAG. CONCLUSIONS: Chronic occupational exposure to chromate causes comprehensive renal impairment though more severity could occur in the tubule than in the glomerular.

Pediatric dosimetry for intrapleural lung injections of (32)P chromic phosphate.

Intracavitary injections of (32)P chromic phosphate are used in the therapy of pleuropulmonary blastoma and pulmonary sarcomas in children. The lung dose, however, has never been calculated despite the potential risk of lung toxicity from treatment. In this work the dosimetry has been calculated in target tissue and lung for pediatric phantoms. Pleural cavities were modeled in the Monte Carlo code MCNP within the pediatric MIRD phantoms. Both the depth-dose curves in the pleural lining and into the lung as well as 3D dose distributions were calculated for either homogeneous or inhomogeneous (32)P activity distributions. Dose-volume histograms for the lung tissue and isodose graphs were generated. The results for the 2D depth-dose curve to the pleural lining and tumor around the pleural cavity correspond well with the point kernel model-based recommendations. With a 2 mm thick pleural lining, one-third of the lung parenchyma volume gets a dose more than 30 Gy (V(30)) for 340 MBq (32)P in a 10 year old. This is close to lung tolerance. Younger children will receive a larger dose to the lung when the lung density remains equal to the adult value; the V(30) relative lung volume for a 5 year old is 35% at an activity of 256 MBq and for a 1 year old 165 MBq yields a V(30) of 43%. At higher densities of the lung tissue V(30) stays below 32%. All activities yield a therapeutic dose of at least 225 Gy in the pleural lining. With a more normal pleural lining thickness (0.5 mm instead of 2 mm) the injected activities will have to be reduced by a factor 5 to obtain tolerable lung doses in pediatric patients. Previous dosimetry recommendations for the adult apply well down to lung surface areas of 400 cm(2). Monte Carlo dosimetry quantitates the three-dimensional dose distribution, providing a better insight into the maximum tolerable activity for this therapy.

Chromated metal products may be hazardous to patients with chromate allergy.

BACKGROUND: Hidden allergen exposure may contribute to persistence and relapse of chromate dermatitis. According to case reports, chromated metal products, such as screws, fittings, etc., may be relevant allergen sources for patients sensitized to chromate. OBJECTIVES: To examine concomitant patch test reactivity to potassium dichromate 0.5% petrolatum (pet.) and three different types of chromated metal rings. PATIENTS/METHODS: Patients with proven or suspected chromate allergy were patch tested with potassium dichromate 0.5% pet. and three different types of chromated metal rings (yellow, olive, and black). Hexavalent chromium Cr(VI) release from the patch tested rings was chemically analysed. RESULTS: Ninety-five patients were tested: 49/95 (52%) reacted to potassium dichromate and 25/95 (26%) reacted to black chromated rings. Reactions to chromated rings exclusively occurred in patients reacting to potassium dichromate. Of 20 patients with a strong reaction to potassium dichromate, 14 reacted to black chromated rings. These were shown to have a high Cr(VI) release. Only two patients reacted to the other chromated rings, which had a very low Cr(VI) release. CONCLUSIONS: Handling chromated metal products must be regarded a hazard to chromate-sensitive patients, in particular those with a strong sensitization.

The hazard of chromium exposure to neonates in Guiyu of China.

Guiyu is one of the most heavily chromium-polluted areas in China due to the presence of numerous electronic waste (e-waste) recycling sites in the region. In this study, we investigate the effect of umbilical cord blood chromium levels (UCBCLs) on neonates from Guiyu and discuss chromium-induced DNA damage of cord blood lymphocyte. Umbilical cord blood samples were collected from neonates of Guiyu (in 2006, n=100; in 2007, n=100) and the neighboring town of Chaonan (in 2006, n=52; in 2007, n=50) that is associated with the fishery. UCBCLs of the neonates were determined by graphite atomizer absorption spectrophotometer. Comet experiment was used to examine lymphocyte DNA damage. Questionnaires to gauge chromium exposure were administered to the mothers of the neonates. The mean UCBCLs of neonates in the Guiyu group in 2006 and 2007 were 303.38 microg/L and 99.90 microg/L with median 93.89 microg/L and 70.60 microg/L, respectively. We observed significant differences between the results in UCBCLs of neonates in Guiyu and the control group (P<0.01). There was no significant difference of UCBCLs in neonates between 2006 and 2007 in Guiyu (P>0.05). Higher levels of chromium in neonates were found to correlate with their mothers' exposure to e-waste recycling. There were significant differences in terms of DNA damage between the Guiyu group and the control group (P<0.05). There was a correlation between DNA damage and the UCBCLs of neonates (P<0.05). There is conclusive evidence that high UCBCLs in neonates exists in e-waste recycling areas in Guiyu and that e-waste recycling activity poses serious environmental problems. Chromium pollution is threatening the health of neonates around the recycling sites.

Effects of intralesional 32-P chromic phosphate in refractory patients with head and neck tumours.

BACKGROUND: The clinical outcome of refractory head and neck (H&N) cancer patients remains poor despite novel treatment strategies. In this pilot study the efficacy of intratumoral injection of 32-P chromic phosphate in 14 patiehts with refractory H&N carcinomas was investigated in terms of response rates and overall survival. PATIENTS AND METHODS: Fourteen patients (median age: 59 years) with either cytostatic drug-resistant tumours or tumours known to be primarily chemotherapy-resistant were entered into the study. After sonographic determination of the tumour volume, 32-P chromic phosphate (74-444 MBq) was injected into the central part of the tumour under sonographic guidance. Follow-up investigations included serial scintigraphy, sonographic examinations and hematological studies. RESULTS: Injection of 32-P chromic phosphate into refractory H&N tumours resulted in remarkable regression. The median survival of all patients was 7.8 months (range: 4-16). Eight patients exhibited a partial response, while 6 patients did not respond to the treatment. In 3 patients thrombocytopenia (grade I/II) was observed, but no other significant side-effects were apparent. Significant pathological and anatomical changes within the tumour tissue were demonstrated. In all cases examined, formation of a cyst within the area of central activity, surrounded by a centrifugal necrotic ring and a marginal fibrotic structure, was found. CONCLUSION: A lack of persistent systematic or local side-effects, as well as noteworthy efficacy, are properties of this novel regional treatment modality with 32-P chromic phosphate. This modality deserves consideration for further clinical trials.