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Biomedical subjects

C Alvarez

Publications and source records attributed to C Alvarez.

At least 217 records · Page 12Linked to original sources
PubMed1990

Naloxone potentiation of cardiovascular responses to sympathomimetic amines in the rat.

The work was aimed at analyzing the ability of naloxone to potentiate 1) the arterial pressure responses to sympathomimetic amines administered i.v. in normotensive anesthetized, pithed, chemically sympathectomized or acutely adrenalectomized rats and 2) the chronotropic responses to norepinephrine in the isolated rat atria. In anesthetized rats, naloxone (2.5-10 mg/kg i.v.) potentiated the pressor responses to epinephrine (2 micrograms/kg). Naloxone (5 mg/kg) significantly potentiated the pressor responses to norepinephrine (1-4 micrograms/kg), phenylephrine (10-50 micrograms/kg) and the reflex pressor responses to a 60-sec carotid occlusion. On the contrary, naloxone did not potentiate the arterial pressure responses to methoxamine (100 micrograms/kg), angiotensin (0.5-2 micrograms/kg) and isoproterenol (1 micrograms/kg). Pithing or acute adrenalectomy did not alter the naloxone-induced potentiation of the pressor responses to norepinephrine (0.125-0.5 micrograms/kg). 6-Hydroxydopamine pretreatment abolished completely the naloxone-induced potentiation of the pressor responses to norepinephrine (0.25-1 micrograms/kg). In isolated rat atria, naloxone (1.4 and 2.8 x 10(-5) M) potentiated the chronotropic responses to norepinephrine (1.5-6 x 10(-8) M). It is suggested that naloxone potentiates cardiovascular responses to sympathomimetic amines by interacting with presynaptic adrenergic mechanisms which could additionally contribute to its pressor effects in acute hypotensive conditions.

Angiotensins↗
PubMed1990

[Alcoholic rhabdomyolysis with myocardial involvement].

A case of severe rhabdomyolysis with extensive myocardial involvement in a 32 year old alcoholic man is reported. He referred effort dyspnea for the last eight months which worsened thirteen days before his death. Admitted at the institute he was obnubilated and dyspneic. Massive pulmonary thromboembolism was suspected and heparin was given. He was then transferred to our intensive care unit in circulatory collapse. A chest Rx showed cardiomegaly. A Swan-Ganz catheter was introduced and abnormal parameters corrected. Evolution was complicated with acute cholecystitis, nosocomial bronchopneumonia and hypoxic brain damage. A net reduction of cardiac size as judged by a chest roentgenogram was noted in the final days. Necropsy showed skeletal and cardiac rhabdomyolysis, early alcoholic cirrhosis, diffuse peritonitis and bronchopneumonia. To our knowledge, this case is the first in the literature to provide anatomical evidence of cardiac rhabdomyolysis, a fact which was suspected on clinical grounds but had not been proven.

Adult↗
PubMed1989

Effect of alloxan diabetes on exocrine pancreatic secretion in the anesthetized rabbit.

The influence of the endocrine pancreas on the exocrine pancreatic secretion of both electrolytes and enzymes was studied in rabbits made diabetic by alloxan administration. No alterations were observed in the flow of pancreatic juice. Bicarbonate concentrations were considerably increased, whereas chloride concentrations were clearly reduced in the alloxan-diabetic rabbits compared with the control animals. Insulin treatment restored anion levels to normal. Similar, although less pronounced changes were seen in the output values of bicarbonate and chloride. There were no significant differences between the control and alloxan-treated animals in the output of sodium and potassium; however, potassium concentrations exhibited a significant rise both in untreated and insulin-treated diabetic rabbits compared with the controls. Total protein and amylase secretion decreased markedly in the diabetic animals. The secretion of amylase was not brought back to control values by additional administration of insulin. These results suggest that the endocrine pancreas plays an extremely important role in exocrine pancreatic function.

Amylases↗
PubMed1989

Chemoanatomic compartments in the human bed nucleus of the stria terminalis.

Recent studies have indicated that peptidergic inputs to the bed nucleus of the stria terminalis are more developed in man than in rodents. To facilitate interspecies comparisons, the definition of the chemoanatomical subdivisions of the human bed nucleus of the stria terminalis was attempted. The immunocytochemistry of synenkephalin, [Met]enkephalin, somatostatin, and tyrosine hydroxylase was analysed on four verticofrontal levels in five control subjects. Four principal sectors were identified in the bed nucleus of the stria terminalis: (1) lateral, displaying an irregular patchy terminal innervation overlapping for the four markers studied; (2) central, characterized by a high density of somatostatin neurons, by pericellular basket-like formations for all markers, and by a shell of dense somatostatin innervation; (3) medial, characterized by a less dense aminergic and peptidergic innervation; and (4) lateroventral, where peptidergic (somatostatin and enkephalin) peridendritic plexuses were prominent. Double-labeling analyses showed that the somatostatin, enkephalin and tyrosine hydroxylase-like immunoreactive terminals rarely converged on the same soma or dendrite even in areas where they appeared closely interdigitated. The differences and similarities of these sectors with those defined in the rat are discussed; a marked development of the lateral and ventral bed nucleus of the stria terminalis is emphasized in man. Islands with dense peptidergic innervation, similar to the ventral bed nucleus of the stria terminalis, extended into the sublenticular substantia innominata (intercalated between the ventral pallidum and the basal magnocellular nucleus). This supports the existence of an extended amygdaloid complex from the amygdala to the bed nucleus of the stria terminalis in the human brain, as has been proposed in the rat. In relation to the literature, the present findings suggest the increasing importance of the central and lateral amygdaloid-bed nucleus of the stria terminals components and of their cortical connections in man while the medial amygdala-bed nucleus of the stria terminalis nuclei, which are preferentially connected to the olfactory system, appear less developed.

Adult↗
PubMed1989

Diuretic and natriuretic properties of fenoldopam in chronic renal failure.

The effect of intravenously administered fenoldopam on diuresis and natriuresis was investigated in a group of 10 patients with advanced chronic renal failure. After an initial basal period of 1 h, a fenoldopam infusion was started and maintained for 12 h at rates varying between 0.025 and 0.1 microgram/kg per min. During the study, blood pressure was measured every 10 min and urine volume, natriuresis and creatinine clearance were measured hourly. Fenoldopam induced a significant increase in urine volume, natriuresis and creatinine clearance (P less than 0.05-0.001) accompanied by a small but significant drop in blood pressure (P less than 0.05-0.01). These results show that for advanced chronic renal failure, fenoldopam has diuretic and natriuretic properties that could be of clinical relevance.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1989

Exocrine pancreas in rabbits fed a copper-deficient diet: structural and functional studies.

The effects of a copper-deficient diet supplemented with D-penicillamine on both the structure and exocrine function of the pancreas were studied in rabbits. The pancreases of the animals kept on this diet for 13 weeks showed lesions in the acinar tissue but not in ductal or islet tissue. The weights of the glands were markedly reduced. Copper deficiency caused a slight (non-significant) reduction in the flow of pancreatic juice and in sodium output and significantly decreased chloride output (p less than 0.01). No changes were observed in bicarbonate and potassium output. Total protein and amylase secretions were maintained at clearly detectable levels in pancreatic juice, although they decreased significantly (p less than 0.01 and p less than 0.001, respectively), in the copper-deficient animals compared with the controls. The pancreases of the animals kept on a copper-deficient diet were seen to maintain their capacity for response to secretin, cholecystokinin (CCK), and bethanechol. Our results show that rabbit pancreatic acinar tissue is less sensitive to copper deficiency than that of other species studied. Additionally, the data on secretion of water and electrolytes suggest that in the rabbit the acinar cells may contribute to the secretory process with a chloride-rich fluid.

Amylases↗
PubMed1989

Electrophoretic pattern of sorbitol dehydrogenase (E.C.1.1.1.14) in human seminal plasma and spermatozoa.

An electrophoretic study of sorbitol dehydrogenase (SORD) in sperm and seminal plasma (SP) was realized. In SP, three phenotypes (one slow band, one fast, and both bands) were observed, corroborating the electrophoretic variability of SP-SORD formerly reported by us, while, in sperm, SORD showed a phenotype of one band faster than the one of SP. Biochemical studies showed that thiol groups participate in the mobility of the SP fast band; furthermore, an interchange of the bands of SP-SORD was observed which suggests that the isozymes are due to conformational isomerism or to molecular aggregates.

Electrophoresis, Polyacrylamide Gel↗
PubMed1989

Screening for thermostability and electrophoretic red blood cell sorbitol dehydrogenase (E.C.1.1.1.14) variants.

A screening for both thermostability and electrophoretic red blood cell sorbitol dehydrogenase (RBC-SORD) variants in blood donors was performed. SORD activity in standard conditions (unheated samples) in 274 individuals was 198 +/- 38.6 mIU/g Hb. The ratio of enzymatic activity after heating (H) to the activity in controls (C) before heating (H/C ratio) was 0.39 +/- 0.10. H/C ratios minor than 0.1 in 3 out of 274 blood donors and higher than 0.9 in 1 were observed. In 208 individuals, four electrophoretic phenotypes were observed: I) Three bands, named a, b and c, with cathodic mobility in 163 individuals (78.36%); II) Two bands a and c in 25 individuals (12.02%); III) Two bands b and c in 14 (6.73%); and IV) One band, c in 6 (2.88%). Studies carried out to characterize the three bands suggest that they are isozymes of the same locus with the observation of an interchange of the bands as a normal phenomena.

Electrophoresis, Disc↗
PubMed1988

Regional and laminar distribution of the dopamine and serotonin innervation in the macaque cerebral cortex: a radioautographic study.

The regional density and laminar distribution of dopamine (DA) and serotonin (5-HT) afferents were investigated in the cerebral cortex of cynomolgus monkeys using a radioautographic technique that is based on the high affinity uptake capacity of these aminergic neurons. Large vibratome sections, 50 micron thick, were incubated with [3H] DA (0.2 microM) and desipramine (5 microM) or with unlabeled norepinephrine (5 microM) and [3H] 5-HT (0.6 microM), which allowed for the specific labeling of the DA and 5-HT innervations, respectively. After fixation, these sections were dried, defatted, and radioautographed by dipping. Semiquantitative data on the DA innervation also were provided by counting [3H] DA-labeled axonal varicosities in radioautographs from 4-micron-thick sections of the slices obtained after epon embedding. The DA innervation was widespread and differed in density and laminar distribution in the agranular and granular cortices. DA afferents were densest in the anterior cingulate (area 24) and the motor areas (areas 4, 6, and supplementary motor area [SMA]). In the latter they displayed a trilaminar pattern of distribution, predominating in layers I, IIIa, and V-VI, with characteristic cluster-like formations in layer IIIa, especially in the medial part of motor areas. In the granular prefrontal (areas 46, 9, 10, 11, 12), parietal (areas 1, 2, 3, 5, 7), temporal (areas 21, 22), and posterior cingulate (area 23) cortices, DA afferents were less dense and showed a bilaminar pattern of distribution, predominating in the depth of layer I and in layers V-VI; density in layers II, III, and IV was only 20% of that in layer I. The lowest density was in the visual cortex, particularly in area 17, where the DA afferents were almost restricted to layer I. The density of 5-HT innervation was generally greater than that of DA except in the motor areas and in the anterior cingulate cortex. Region-specific laminar patterns characterized (1) motor areas where a lower density in layer III contrasted with the clusters of DA axons in the same layer; (2) the primary visual cortex (area 17), where two bands of higher density in layers III-IV and layer V outlined a poorly innervated zone in layer IVc-beta; (3) the peristriate area 18, where the 5-HT network was relatively loose but with a denser band in layer III. Thus, DA innervation of the cerebral cortex displays major differences between rodents and primates, characterized by expanded cortical targets and by a highly differentiated laminar distribution.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Genetics of the black-tailed red plumage pattern in Villafranquina chickens.

Data are presented on the genetics of the plumage color of the Villafranquina, a breed of Spanish chicken representing a black-tailed red type of the columbian restriction pattern. Crosses between Villafranquina females, which show a large amount of secondary pattern, and Brown and Buttercup tester males suggested that this breed carries the brown allele (eb) at the E-locus. This allele is modified by the dark-brown columbian-like gene (Db), resulting in the plumage pattern characteristic of the breed. The degree of expression of Db varies markedly depending on other key genes present. This gene acted as an incomplete dominant when crossed to brown (eb) and buttercup (ebc) tester lines. However, in the presence of the birchen (ER) gene, Db was recessive in females but dominant in males, suggesting sex-influenced inheritance. Silver (S) does not alter the brown down of Db-modified ER, although it does express itself readily on a brown (eb) background. Variability in the expression of Db in both F1 and F2 populations suggests that it sometimes interacts with not yet identified modifying genes.

Animals↗
PubMed1988

Total creatine kinase (CK) and CK-B activity in maternal blood and cord-blood samples after vaginal and cesarean births.

We studied variations in the activity of total creatine kinase (CK; EC 2.7.3.2) and of CK-B in maternal and cord-blood samples, comparing data obtained for vaginal and cesarean births. CK-B activity was determined with an immunoinhibition assay. In all cases, there was a significant postpartum increase in total CK and in CK-B activity in maternal sera, whereas cord-blood samples showed no significant differences between activities in arterial and venous blood for either vaginal or cesarean births. Statistically significant differences were found in CK-B activity, but not in total CK, between cord-blood samples from vaginal births and those from cesareans.

Cesarean Section↗