In this study we examined the hypothesis that 17 beta-estradiol exerts both rapid and direct, nongenomic effects of cells in the endochondral pathway. To do this, we used a cell culture model in which chondrocytes at two distinct stages of cell maturation are isolated from the costochondral cartilage of male and female rats, and examined the short-term effect of 17 alpha- and 17 beta-estradiol on [14C]arachidonic acid turnover in the cell layer and phospholipase A2 specific activity in plasma membranes and extracellular matrix vesicles isolated from similarly prepared cultures. In addition, the effect of 17 alpha- and 17 beta-estradiol on plasma membrane and matrix vesicle membrane fluidity was assessed. The effect of hormone on arachidonic acid turnover was rapid, time- and concentration-dependent, stereo-specific, and cell maturation-specific. Only resting zone cells from female rats were affected, and only 17 beta-estradiol elicited a response. Similarly, only female rat resting zone chondrocytes exhibited a change in phospholipase A2 activity after a 24 h exposure to hormone, causing an increase in enzyme activity in the matrix vesicles, but not plasma membranes. When isolated membranes were incubated directly with hormone, membrane fluidity was decreased in both plasma membranes and matrix vesicles isolated from female rat resting zone chondrocyte cultures. This nongenomic effect was dose-dependent and stereo-specific and differentially expressed in the two membrane fractions with respect to time course and magnitude of response. These results support the hypothesis that 17 beta-estradiol has a rapid action on chondrocyte membrane lipid metabolism and suggest that specific membrane components, characteristic of a particular sex and state of cell maturation, are involved in the nongenomic effects of this sex hormone on isolated matrix vesicles and plasma membranes.
One black-tip reef shark (Camharhinur mclanqtms) was found dead without previous signs of disease. Major lesions consisted in cutaneous erythema, mainly at the base of the fins, focal to diffuse inflammatory lesions in pius and intestinal wall, and discrete haemorrhages in the same organs, liver and kidneys. Microcolonies of Gram-negative rods were observed in the lamina propia of pius, underneath the intestinal mucosa and randomly distributed in the renal and hepatic parenchymas. Also, emboli containing Gramnegative rods were observed in capillaries of these organs. Aemmonur suhoni&h subsp. suhonikh was isolated in pure culture from pius, liver and intestine. Specific immunostaining confirmed the relationship between the isolate and lesion-associated bacteria. No previous reports on this infection in sharks have been found in the literature.One black-tip reef shark (Canbadinus melanopteru) allocated in the facilities of the Zoo of Madrid was found dead without previous signs of disease. It was maintained alone in a marine water tank (9625 I total volume) under standard conditions for this species. Water was regularly oxygenated, recirculated (12 OOO Vh), filtered and monthly renovated. The determination of water quality parameters, such as nitrites concentration, pH and salinity, was performed weekly.The water temperature was maintained at 27'C. Frozen mackerel and herring were thawed and used as feed for the shark. N o sudden changes in environmental conditions or feeding had occurred prior to the shark's death.Dinoflagellated-associated intoxication was first considered to be the cause of death.However, no toxin was found following standard procedures (WILLIAMS, 1984), in neither the filter material nor the water.The shark was sent to the School of Veterinary Medicine of Madrid for necropsy. External examination revealed a diffuse cutaneous erythema, mainly at the base of the dorsal and pectoral fins, and especially remarkable around the anal area and gill slits. An internal examination revealed the presence of discrete haemorrhagic lesions in several internal organs. Kidneys and liver showed haemorrhages (approximately 0.5-1 cm in diameter) randomly distributed o n the surface and throughout the parenchyma. Submucosal haemorrhagic lesions were also found in U. S. CapriBht ~~c p l n n c c Gntcr cod^ Suumrnt: 0931 -1 793/98/4507-0443$14.00/0
An experimental study on the effects of supplementation with antioxidant vitamins on urine lipid peroxidation products was performed in 21 young healthy men. The subjects ingested placebo, 1 g of vitamin C, or 100 mg of vitamin E per day just after the midday meal during 30 days. Urine samples were obtained 0, 15 and 30 days after the beginning of the study. These samples were analyzed by spectrophotometry or fluorometry after reaction with thiobarbituric acid. Prescan fluorometric studies of the thiobarbituric acid reactive substances in both malondialdehyde standards and urine samples indicated 503 nm and 548 nm as optimum excitation and emission wavelengths. The fluorescence measurements proved to be superior both in terms of selectivity and capacity of detection of antioxidant effects in relation to spectrophotometry. Identical emission peaks were obtained with malondialdehyde standards and urine samples, showing the specificity of the fluorometric method. When measured by fluorometry, the urine of the subjects supplemented with vitamin E showed significantly and progressively smaller lipid peroxidation products as the time of supplementation increased, reaching a 27% decrease at the end of the longitudinal trial. The results indicate the usefulness of the fluorescent measurement of urine thiobarbituric acid reactive substances to easily and rapidly detect variations in whole body oxidative stress in humans. They also show the capacity of safe vitamin E dietary doses to decrease endogenous oxidative stress in healthy humans routinely performing their normal activities.
There are a large number of pests which are detrimental to plant production, specifically to banana cultivation, and the use of pesticides is the main method of control of these pests. Therefore, the number of active substances in pesticides has been steadily increasing since before the Second World War. There is growing consumer concern about the health effects of pesticide residues and there is certainly evidence of a link between pesticide exposure and the prevalence of chronic diseases. Therefore, it is of particular interest to study the presence of pesticide residues in bananas and their toxicological, agricultural and legal implications. In this study, the content of pesticide residues in bananas produced in the Canary Islands during a ten-year period from 2008 to 2017 was determined. A total of 733 samples of bananas were analysed during the study period, in which 191 different active substances were investigated, involving 103,641 assessments. The samples analysed were selected in such a way that they are representative of the banana sector in the Canary Islands as a whole, taking into account geographical and climatic factors, cultivation methods and the processing of bananas in packaging, which are the differentiating factors in the use of pesticides. The reference parameter for the residue investigation is the MRL (maximum residue limit).
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