Articles: manganese.
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Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic manganese compound recently approved for use in the United States as a gasoline additive. MMT use is expected to increase. This Commentary analyzes the impact of MMT use on population exposure to manganese, the health effects associated with manganese exposure, and the possibility that MMT use will lead to toxicity in the population. ⋯ Common sense and prudence therefore dictate that MMT not be used until further data are available and its safety is confirmed. Several measures are recommended to address the impending use of MMT in the U. S. gasoline supply.
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Arch. Environ. Contam. Toxicol. · Nov 1992
Disposition, behavior, and toxicity of methylcyclopentadienyl manganese tricarbonyl in the mouse.
The disposition and toxicity of methylcyclopentadienyl manganese tricarbonyl (MMT), a potential substitute for lead in gasoline, was studied to investigate the different adverse effects in ddY mice after chronic oral administration at 0.5 g/kg in food for 12 months. There was no significant difference in intake between the control mice and the mice exposed to MMT (MMT group), but those given MMT suppressed weight significantly. The manganese content in the organs of the MMT group was 4.4-1.5 times significantly higher than that of the control group. ⋯ The urinary excretion of manganese in the MMT group was 5.4% of the daily oral intake. The organometallic form of the manganese involved is apparently absorbed more readily than inorganic forms. The stronger toxicity of MMT to the tissue than that of inorganic manganese is attributed to the significantly higher blood and tissue levels of manganese in the MMT group.
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Review
Occupational and environmental exposures and nonspecific lung disease--a review of selected studies.
Selected studies show that nonspecific lung diseases are a major occupational and environmental health hazard. Exposure to mineral dusts (such as cement and brown coal) and organic dusts (cotton, hemp and flour) as well as manganese and gaseous irritants causes significant upper respiratory tract injury. ⋯ Interpretation of the results is difficult due to uncontrolled confounding. Measures for preventing lung impairments include exposure reduction and preemployment examination of workers.
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Comparative Study
[The clinical value of Mn-DPDP: a new paramagnetic hepatobiliary contrast medium for magnetic resonance tomography of the liver].
In an open prospective study the tolerance and diagnostic value of the new hepatobiliary contrast agent Mn-DPDP in MR imaging was evaluated in 20 patients suspected of having focal liver lesions. T1- and T2-weighted spin-echo sequences and T1-weighted gradient-echo sequences were obtained before and after intravenous application of Mn-DPDP. In all patients the signal to noise (S/N) values of normal liver tissue increased significantly after application of Mn-DPDP. ⋯ In metastatic disease of the liver 25-120% more lesions could be detected in MRI after Mn-DPDP-application, compared with the unenhanced images. In 5 patients the lesions showed significant enhancement of Mn-DPDP (2 cirrhotic nodules, 2 hepatocellular carcinomas, 1 focal nodular hyperplasia). Our preliminary results indicate that Mn-DPDP is a well-tolerated contrast agent useful for the detection and differentiation of liver lesions in MR imaging.
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Scan Electron Microsc · Jan 1986
Genes, manganese, and zinc in formation of otoconia: labeling, recovery, and maternal effects.
Published studies indicate that genes and dietary manganese deficiency cause vestibular defects and ataxic behaviors. Manganese deficiency during development causes otoconial defects in mice, rats, guinea pigs, and chicks. Mutant genes cause otoconial defects in mice, mink, and poultry. ⋯ The effectiveness of zinc but not of manganese is related to maternal genotype (+/pa vs. pa/pa). The effect of supplementation of the dams with zinc but not with manganese increases over successive litters. These studies indicate the potential for interaction of genes and trace minerals on otoconial formation and maintenance.