Metabolical effects of Folidol 600 on the neotropical freshwater fish matrinxã, Brycon cephalus

The neotropical freshwater fish matrinx?, Brycon cephalus (Günther, 1869), was exposed to 1/3 of 96 h-LC50 of Folidol 600 (methyl parathion) for 96 h and allowed to recover for 24, 48, 96, and 192 h. Acetylcholinesterase (AChE), alanine aminotransferase (ALAT), aspartate aminotransferase (AAT), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), and glutamate dehydrogenase (GDH) were assayed in brain, liver, muscle, and plasma. Plasma and brain AChE activities were strongly inhibited (64% and 87%, respectively), remaining low in the brain during recovery. Liver ALAT decreased 59.4% and plasma ALAT increased 94.2%. This response, associated with GDH reduction during the recovery period, was attributed to impairment of amino acid metabolism and to liver damage. The increase of heart and plasma AAT suggested tissue injury. Liver and plasma LDH and MDH did not change during the exposure to Folidol, but liver MDH decreased 34% during recovery, indicating a failure of oxidative metabolism in such tissue. Hepatic glycogen and glucose levels decreased 80.4 and 55%, respectively, followed by glucose mobilization to the plasma. The hepatic and muscular profile of lactate after recovery suggested gluconeogenesis without tissue hypoxia. These results revealed that methyl parathion affects the intermediary metabolism of matrinx? and that the assayed enzymes can work as good biomarkers of organophosphorus pesticide contamination.     

Cassava cyanogens and fish mercury are high but safely consumed in the diet of native Amazonians

The two most important staple foods (cassava and fish) in the diet of native Amazonians contain neurotoxins (linamarin and monomethyl mercury, MMHg). These same neurotoxins are public health issues in other parts of the world. Factors such as chemistry, environment, and human ecology determine the endemism of neuropathies caused by consumption of cassava (Manihot esculenta Crantz) and fish. Linamarin is a natural component of cassava tubers that can be destroyed before consumption by proper processing. Furthermore, small amounts of the toxin absorbed by people consuming cassava can be effectively metabolized if the diet contains adequate protein-containing sulfur amino acids. Naturally occurring Hg in the waters of the Amazonian rain forest is methylated to MMHg by microorganisms and bioconcentrated in the aquatic food chain. There is no effective method for MMHg removal from fish. Despite high concentrations of naturally occurring neurotoxins in cassava (linamarin) and fish (MMHg), daily consumption of these foods in large amounts over the course of a lifetime poses no health hazards for Amazonians.     

A cholesterol biosynthesis inhibitor from<Emphasis Type="Italic">Rhizopus oryzae</Emphasis>

A bile acid derivative, methyl cholate (1), was isolated from EtOAc extract of the fungus Rhizopus oryzae as a cholesterol biosynthesis inhibitor. It showed moderate inhibitory activity on cholesterol biosynthesis in human Chang liver cells. Compound 1 exhibited inhibitory effect on the later step of cholesterol biosynthesis, indicating that its action mode is different from that of statins that act on the HMG-CoA reductase.     

Retrospective and Current Risks of Mercury to Panthers in the Florida Everglades

Florida panthers are an endangered species inhabiting south Florida. Hg has been suggested as a causative factor for low populations and some reported panther deaths, but a quantitative assessment of risks has never been performed. This study quantitatively evaluated retrospective (pre-1992) and current (2002) risks of chronic dietary Hg exposures to panthers in the Florida Everglades. A probabilistic assessment of Hg risks was performed using a dietary exposure model and Latin Hypercube sampling that incorporated the variability and uncertainty in ingestion rate, diet, body weight, and mercury exposure of panthers. Hazard quotients (HQs) for retrospective risks ranged from less than 0.1-20, with a 46% probability of exceeding chronic dietary thresholds for methylmercury. Retrospective risks of developing clinical symptoms, including ataxia and convulsions, had an HQ range of <0.1-5.4 with a 17% probability of exceeding an HQ of 1. Current risks were substantially lower (4% probability of exceedences; HQ range <0.1-3.5) because of an estimated 70-90% decline in Hg exposure to panthers over the last decade. Under worst case conditions of panthers consuming only raccoons from the most contaminated area of the Everglades, current risks of developing clinical symptoms that may lead to death was 4.6%. Current risks of mercury poisoning of panthers with a diversified diet was 0.1% (HQ range of <0.1-1.4). The results of this assessment indicate that past Hg exposures likely adversely affected panthers in the Everglades, but current risks of Hg are low.     

Common loon eggs as indicators of methylmercury availability in North America

Increased anthropogenic mercury (Hg) deposition since pre-industrial times, and subsequent transformation of inorganic Hg to methylmercury (MeHg) in aquatic environments, has created areas in North America where Hg poses a relatively high risk to wildlife, especially long-lived, piscivorous species. From 1995 to 2001, we opportunistically collected 577 eggs abandoned by Common Loons from eight states. Egg-Hg concentrations ranged from 0.07 to 4.42 µg/g (ww) or 0.10 to 19.40 µg/g (dw). Mercury was higher in eastern than in western North America. Female blood-Hg concentrations strongly correlated with those of eggs from the same territory even though the mean intraclutch Hg difference was 25%. In New England, egg volume declined significantly as egg-Hg concentrations increased. Fertility was not related to egg-Hg concentrations. Based on existing literature and this study's findings, egg-Hg risk levels were established and applied to our US data set and an existing Canadian data set. Regionally, we found the greatest risk levels in northeastern North America. With few exceptions, loon eggs are suitable indicators of methylmercury availability on lakes with territorial pairs.     

Two new methyl chanofruticosinates from Kopsia flavida blume

Two new indole alkaloids with the methyl chanofruticosinate skeletal system viz., methyl 3-oxo-12-methoxy- N 1 -decarbomethoxy-14,15-didehydrochanofruticosinate ( 1 ) and methyl 3-oxo-11,12-methylenedioxy- N 1 -decarbomethoxy-14,15-didehydrochanofruticosinate ( 2 ), together with four known compounds, methyl 12-methoxy- N 1 -decarbomethoxychanofruticosinate, methyl 12-methoxychanofruticosinate, methyl 11,12-dimethoxychanofruticosinate and methyl 11,12-methylenedioxy- N 1 -decarbomethoxychanofruticosinate, were isolated in continuing studies on the leaves of Kopsia flavida Blume. The structures of the new indole alkaloids were assigned by NMR spectral data using various 2D-techniques.     

N-甲基-D-门冬氨酸受体主亚基单克隆抗体抗谷氨酸兴奋毒性的体外实验研究

目的 研究人N一甲基-D-门冬氨酸受体(NMDAR,NR)主亚基(NRl)单克隆抗体mAbN1是否对兴奋毒性脑损害有防护作用。方法 取10只新生大鼠海马神经细胞进行体外原代培养,建立了谷氨酸对培养海马神经细胞兴奋毒性神经损伤模型,观察抗体保护后神经细胞形态,检测细胞存活率(锥虫蓝拒染法)和细胞培养上清乳酸脱氢酶漏出量,每组2个平行皿,实验重复4次。结果经0、3μmoL／LmAbNl预处理后,神经元具有明显抗谷氨酸兴奋毒性损伤能力,存活率提高35％;抗体表位合成肽可以阻断这种保护,提示该抗体的保护功能是特异性的。结论 NRl单克隆抗体mAbNl具有体外抗兴奋毒作用,该研究为兴奋毒性脑损害抗体治疗提供了重要依据。     

Mortality from cardiovascular diseases and exposure to inorganic mercury

OBJECTIVE—To study the mortality from cardiovascular and other chronic non-neoplastic diseases after long term exposure to inorganic mercury. Limited information is available on the effect of chronic exposure to mercury on the cardiovascular system.
METHODS—The mortality was studied among 6784 male and 265 female workers from four mercury mines and mills in Spain, Slovenia, Italy, and the Ukraine. Workers were employed between 1900 and 1990; the follow up period lasted from the 1950s to the 1990s. The mortality of the workers was compared with national reference rates.
RESULTS—Among men, there was a slight increase in overall mortality (standardised mortality ratio (SMR) 1.08, 95% confidence interval (95% CI) 1.04 to 1.12). An increased mortality was found from hypertension (SMR 1.46, 95% CI 1.08 to 1.93), heart diseases other than ischaemic (SMR 1.36, 95% CI 1.20 to 1.53), pneumoconiosis (SMR 27.1, 95% CI 23.1 to 31.6), and nephritis and nephrosis (SMR 1.55, 95% CI 1.13 to 2.06). The increase in mortality from cardiovascular diseases was not consistent among countries. Mortality from hypertension and other heart diseases increased with estimated cumulative exposure to mercury; mortality from ischaemic heart disease and cerebrovascular diseases increased with duration of employment, but not with estimated exposure to mercury. Results among women were hampered by few deaths.
CONCLUSION—Despite limited quantitative data on exposure, possible confounding, and likely misclassification of disease, the study suggests a possible association between employment in mercury mining and refining and risk in some groups of cardiovascular diseases.


     

Combined toxicity of dissolved mercury with copper, lead and cadmium on embryogenesis and early larval growth of the Paracentrotus lividus sea-urchin

The individual and combined toxicity of dissolved mercury, copper, lead and cadmium has been investigated by using the Paracentrotus lividus sea-urchin embryo-larval bioassay. Embryogenesis success and early larval growth have been recorded after incubation of fertilised eggs in seawater, both with single metals and binary combinations of Hg with every other metal. For individual metals the ranking of toxicity was Hg > Cu > Pb > Cd, with EC₅₀ values of 21.9, 66.8, 509 and 9240g/l, respectively. Lowest observed effect concentrations (LOEC) for early larval growth were approximately three times lower than the EC₅₀ values for Hg, Cu and Pb, and more than two orders of magnitude lower for Cd, emphasizing the danger of underestimating toxicity when only lethal effects are recorded. Marking & Dawson's additive indices ranged from 0.10 to 0.19, indicating additive effects with a slight trend to synergism, which was statistically significant for the Hg–Pb combination only. Hayes' additive indices were within the margins considered acceptable to describe additive interactions.