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A Losada

Publications and source records attributed to A Losada.

66 records · Page 4Linked to original sources
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Prevention of dexamethasone-induced lymphocytic apoptosis in the intestine and in Peyer patches by enteral nutrition.

BACKGROUND: Apoptosis is a programmed cell death, genetically controlled, that can be activated by physiological and pathophysiological events and by the administration of several drugs, including the exogenous administration of corticosteroids. The aim of this study was to develop a rat model of intestinal lymphocytic apoptosis induced by dexamethasone to determine if apoptosis could be prevented by enteral or parenteral nutrition. METHODS: Male Sprague-Dawley rats were used. On day 0, the right internal jugular vein was catheterized for parenteral nutrition, and a silicone tube was inserted into the duodenum for enteral feeding. Animals (n = 6/group) were randomly assigned to one of the following 3 feeding regimens: an immune-enhancing enteral diet; its placebo (the same formula without immunonutrients); and isocaloric isonitrogenous parenteral nutrition. On the seventh day, 200 microg of dexamethasone or vehicle were administered by i.v. bolus, and the diets were continued for 1 more day. Intestinal Peyer patches and thymic lymphocytic apoptosis were determined both by flow-cytometry and immunohistochemistry. RESULTS: A single dexamethasone dose (200 microg/rat) administered to surgically treated rats fasted for 18 hours, 24 hours later, caused massive intestinal and Peyer patches lymphocytic apoptosis (96 +/- 2% and 85 +/- 5%, respectively; p < .0001 versus vehicle in both kinds of tissue). Lymphocytic apoptosis was reduced to almost indetectable levels in intestinal and lamina propia lymphocytes (from 96 +/- 2% to <0.6%; p < .0001). Peyer patches lymphocytic apoptosis was reduced as well (from 85 +/- 5% to 15 +/- 7.1%; p < .001) in animals prefed the 2 enteral nutrition formulas. Those prefed parenteral nutrition only showed a partial decrease of lymphocytic apoptosis in the intestine (from 96 +/- 2% to 53 +/- 23%; p < .001). Nutrition had no effect on the dexamethasone-induced thymus involution. CONCLUSIONS: Enteral nutrition prevents intestinal intraepithelial and lamina propia lymphocytic apoptosis due to dexamethasone. These findings support the use of early enteral nutrition in critically ill patients treated with corticosteroids.

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PubMedDate not supplied

[Effects of carvedilol in rats with induced chronic kidney failure].

Hypertensive mechanisms are postulated to play a major role in the progressive glomerulosclerosis (GS) after renal mass reduction. Previous studies have demonstrated differences in the progression to glomerulosclerosis with the use of different antihypertensive drugs. We analyzed whether the use of carvedilol (CVD), a new beta-adrenoceptor antagonist and vasodilator slows the progression of glomerulosclerosis in 5/6 nephrectomised (Nx) rats. Fifty-four adult Sprague-Dawley rats were distributed among five groups, four with 5/6 Nx, vehicle treated and CVD at 5, 10 and 20 mg/kg/day and sham (no renal ablation or drug treatment). Tailcuff blood pressure, serum creatinine and urine protein concentration were measured. At the end of the experiment remnant kidney was removed for morphometric studies. Rats treated with 10 and 20 mg/kg/day of CVD showed controlled systemic blood pressure. Serum creatinine was similar in all treated groups with CVD, and half the levels observed in the vehicle-treated rats. The prevalence of glomerular lesions was closely associated with the degree of proteinuria. Eleven weeks after 5/6 Nx, vehicle-treated rats exhibited marked GS with 76% of affected glomeruli and creatinine retention. By contrast, renal injury was largely prevent in those rats treated with 10 and 20 mg/kg/day of CVD. Tuft enlargement occurred in all groups but was more prominent in vehicle-treated group, 1.5 times higher than the group treated with 20 mg/kg/day of CVD. Although, these data demonstrate the importance of systemic blood pressure control in the renal protective efficacy of carvedilol, other less-known mechanisms of this drug must be investigated.

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