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Biomedical subjects

L A Fernandez

Publications and source records attributed to L A Fernandez.

96 records · Page 6Linked to original sources
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Fluorescence photograph of stomach cancer tumors in Wistar rats: computerized analysis.

Detection of cancer in early stages with hematoporphyrin derivatives (HpD) is highly limited by the low fluorescence quantum yield, the strong autofluorescent components of the tissue, and the low contrast between normal and tumoral tissue when fluorescent photographs are taken. A new computer analysis based on digital subtraction of photographs before and after the administration of HpD, allows a total autofluorescence extraction, resulting in a remarkable increase of contrast between tumors and normal tissue. Experiments, with this computerized imaging system in adenocarcinoma of the stomach in Wistar rats, confirms the reliability of this method.

Animals↗
PubMedDate not supplied

Angiotensin II decreases mortality rate in gerbils with unilateral carotid ligation.

Evidence indicates that after vascular occlusion, infusion of angiotensin II restores blood supply to ischemic tissues by stimulating the development of collateral circulation through a mechanism independent of the mechanical effects of increased blood pressure. To test this effect in focal cerebral ischemia, angiotensin II was intravenously administered for four hours to gerbils immediately after unilateral carotid ligation. Three different pressor doses, 50, 250, and 500 ng/kg/min, were used, and mortality rate was evaluated at 1 and 2 days after vascular occlusion. Two additional groups similarly prepared were infused either with saline or with the pressor agent metaraminol. There was a significant inverse relationship between the infusion dose of angiotensin II and mortality: the greater the infusion dose of angiotensin II, the lower the mortality rate. Infusion of metaraminol, at the dose chosen to mimic the pressor effect of the highest angiotensin II dose, yielded a mortality rate which was statistically indistinguishable from that obtained with saline infusion. It is concluded that the mortality rate after unilateral carotid occlusion is significantly reduced by intravenous administration of angiotensin II through mechanisms unrelated to its hypertensive action. Evidence suggests that this may occur by the enhancement of the development of collateral circulation and therefore the reduction of the severity of brain ischemia.

Angiotensin II↗
PubMedDate not supplied

Pulmonary embolism with bone fragments following vertebral body marrow infusion for tolerance induction.

Protocols of donor bone marrow infusion for tolerance induction are receiving increasing attention in clinical trials of organ allotransplantation. We report pulmonary embolism with bone fragments following vertebral body marrow infusion in a recipient of a liver and intestinal transplant. Even though pulmonary embolism with bony microfragments has been widely described following bone marrow transplantation, the use of single, high-dose donor bone marrow infusion and/or multiple infusions currently under clinical investigation for induction of donor specific unresponsiveness, may warrant the implementation of additional steps in the vertebral body marrow processing technique to decrease or eliminate the component of bony microfragments in the final preparation.

Bezoars↗
PubMedDate not supplied

[Duality of angiotensin II receptors and risk for stroke and cancer: what is the connection?].

Angiotensin II (AII) acts by 2 types of receptors: the ATI receptor which mediates its actions on vasoconstriction, renin (inhibition) and aldosterone (stimulation) secretions, cellular proliferation and angiogenesis and the non-AT1 (often called AT2) receptors. Mainly expressed in the embryon these latter may favor cellular differentiation and recruitment of collateral circulation. Angiotensin converting enzyme inhibitors (ACEI) decrease the synthesis of All and therefore the stimulation of both receptor types whereas AT1-receptor antagonists (AT1RA) block only the stimulation of these latter and increase the stimulation of AT2 receptor since they increase the production of All secondarily to the inhibition of the feedback of renin secretion by All. Experimentally ACEI and AT1RA decrease angiogenesis and cellular proliferation and favor cellular differentiation which could explain the protective effect of ACEI against cancer suggested recently in a Scotish study. Despite of their common suppressive effect on angiogenesis AT1RA may better than ACEI protect against ischemic events specially the cerebral ones because they favor the rapid recruitment of collateral circulation. This has been demonstrated for losartan in case of abrupt ligation of the carotid in the gerbil since its previous administration protects against fatal cerebral ischemia whereas its previous administration with enalapril abolishes this protection. These data may explain why, in the CAPP trial, captopril which has prevented more effectively diabetes occurrence could not be proved superior to diuretics and/or betablocker in the prevention of myocardial infarction and specially of strokes for which exist on the contrary a suspicion of a lower protection. Therefore a comparative trial between AT1RA and ACEI in the prevention of stroke recurrence should appear as a priority for Public Health and Pharmaceutical Industry Authorities.

Angiotensin II↗