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Biomedical subjects

C Alvarez

Publications and source records attributed to C Alvarez.

At least 37 records · Page 2Linked to original sources
PubMed1991

Alterations of dopaminergic and noradrenergic innervations in motor cortex in Parkinson's disease.

The motor areas of the cerebral cortex contain dense dopaminergic and noradrenergic innervation in humans. We looked for changes of these innervations in cases with Parkinson's disease (PD). The density of fibers immunolabeled with tyrosine hydroxylase or dopamine-beta-hydroxylase was evaluated in the primary motor, premotor, and prefrontal cortical regions in 6 cases with PD and 7 control cases. Reductions of both noradrenergic and dopaminergic cortical innervations were observed, with similar magnitudes of reduction found in the motor and prefrontal regions of the cortex. Depletion of noradrenergic innervation was diffuse, involving all cortical laminae. Depletion of dopaminergic innervation was laminar specific, with the most significant reductions in layers I and II; reductions in layers V and VI were either less marked (prefrontal cortex) or not detectable (primary motor). The results suggest the existence of two separate mesocortical dopaminergic systems in humans, with the one distributing to upper cortical layers being preferentially involved in PD.

Aged↗
PubMed1991

Modulatory action of acetylcholine on cerebrovascular sympathetic neurotransmission.

1. Acetylcholine (10 micrograms/min) diminished the electrically-induced cerebral blood flow reductions. Atropine (1-2 mg) partially blocked this inhibitory effect. 2. Exogenously administered noradrenaline (1-10 micrograms) and tyramine (50-500 micrograms) reduced cerebral blood flow but this effect was unchanged by acetylcholine infusion. 3. Acetylcholine inhibited the nonadrenergic component of the electrically-induced contraction at a concentration greater than or equal to 10(-6) M and potentiated the adrenergic component at a concentration greater than or equal to 10(5) M. Atropine 10(-7) M) inhibited both of these effects. In addition, acetylcholine (10(-4) M) enhanced the electrically-evoked [3H]noradrenaline overflow. 4. These results show that: (a) acetylcholine modulates cerebrovascular sympathetic neurotransmission by acting on muscarinic receptors; and (b) the potentiating effect of acetylcholine is achieved by a mechanism involving increases in noradrenaline release.

Acetylcholine↗
PubMed1991

New perspectives in the surgical management of chronic pancreatitis.

Although the etiology of pain in chronic pancreatitis remains uncertain, that symptom remains the most common indication for surgery in these patients. Current endoscopic and imaging techniques now permit accurate definition of the morphology of the disease. Thus, surgical intervention can be more selectively applied to address specific abnormalities. Pancreaticojejunostomy should be the first line of surgical therapy if the ductal system is dilated. When, in addition, the head of the pancreas is enlarged and inflamed, the operation should include a localized resection of the head, preserving the stomach and duodenum. If the duct is not dilated, some form of pancreatic resection is indicated. The resection should be limited to the most severely diseased part of the pancreas. Efforts should be made to preserve as much pancreatic tissue as possible, while maintaining normal gastrointestinal continuity. In this way, the nutritional and metabolic consequences of pancreatic resection will be minimized.

Chronic Disease↗
PubMed1991

Further study on the plumage pattern of the Blue Andalusian breed.

The genetic basis for plumage color of the Blue Andalusian breed was studied. Results of crosses between Blue Andalusian females and Brown (eb/eb) tester males showed that this genetic stock was E/E and did not carry a columbian-type gene. This fact was further verified by the cross between Blue Andalusian males and Melanotic Prat (eWh/eWh Co/Co Ml/Ml) females. It is suggested that the Bl/bl+ genotype is effective in changing black to blue pigment when only one eumelanizing gene is present in the genetic background, but it is ineffective in the presence of two different genes producing eumelanin simultaneously. With an E/E genotype, Bl/bl+ does not change black pigment to blue in the areas where the melanotic (Ml) or lacing (Lg) genes produce black pigment, resulting in the laced plumage pattern of the Blue Andalusian (E/E Bl/bl+ Ml-Lg/Ml-Lg). On a non-E/E genetic background, a single dosage of Bl changes the black pigment to blue in the presence of the melanotic or lacing genes. Double-laced phenotypes were not found in either cross, thereby causing the authors to question the role of Co in double and single-laced patterns. Linkage between Ml and Lg was estimated to be 12.2% +/- 2.1 (SE).

Animals↗
PubMed1991

[Acute pancreatitis associated with primary hyperparathyroidism].

A case of acute pancreatitis associated with primary hyperparathyroidism is reported. There was none of usual causes of pancreatitis, which did not recur following the removal of a parathyroid adenoma. There are over one hundred of cases of acute or chronic pancreatitis associated with hyperparathyroidism in the literature, suggesting a causal relationship between the two entities. The pancreatic disease has been attributed either to the hypercalcemia or to the excess of circulating parathyroid hormone. However, some authors have recently questioned any link between these two diseases.

Acute Disease↗
PubMed1991

[Adrenal gland gammagraphy in the study of Cushing's syndrome-disease].

A retrospective study is presented of 19 patients who suffered Hypercortisolism who were examined by adrenal gammagraphy, echography, and CT scan in order to evaluate the usefulness of gammagraphy in the diagnostic approximation of this pathology. The gammagraphy findings had an excellent correlation with anatomopathologic findings, probably due to the combined morphologic and functional evaluation obtained with this technique which facilitates a complementary vision to the other diagnostic image exams (CT scan and echography) which, although they are the first choice given their availability and good resolution, they can easily lead to diagnostic errors which can be avoided if we can perform an adrenal gammagraphy; it is of special interest in the study of macro-micro-nodular hyperplasia and its differentiation from single adenomas.

Adrenal Cortex↗
PubMed1991

Glomerular lesions in Aleutian disease of mink (Mustela vison): a morphological and differential morphometrical study.

A morphological and morphometrical study has been carried out on glomerular lesions in mink with spontaneous Aleutian disease, using the WHO classification for Systemic Lupus Erytematous Nefritis. 154 renal samples from sick animals and 10 samples from uninfected mink were processed by routine histopathological techniques and metacrylate inclusions. The samples were studied quantitatively with an automatic image analyzer. 5 forms of glomerulonephritis (GN) were identified: mesangial glomerulonephritis (n = 13), focal and segmental GN (n = 10), diffuse GN (n = 99), membranous GN (n = 12) and advanced sclerosing GN (n = 10) and were associated with the degree of interstitial plasmocytosis. Glomerule morphometry was shown to be an excellent method for identifying the type of lesion, while it quantified the participation of various glomerular elements in the lesion.

Aleutian Mink Disease↗
PubMed1991

[Effects of ursodeoxycholic acid in patients with cholestasis of pregnancy].

In an open, pilot study, the efficacy and safety of ursodeoxycholic acid (UDCA) in the treatment of intrahepatic cholestasis of pregnancy was investigated. Four patients received 1 g/day of UDCA during 20 days and another 2 patients received 2 identical periods of treatment separated by a 14-day interval free of drug. Pruritus and serum levels of total bile salts and glutamic-pyruvic transaminase improved significantly during treatment with UDCA. Although pruritus and the laboratory alterations had a relapse in the second week after UDCA was discontinued, they improved again in the 2 patients who received a second treatment with UDCA. No adverse reactions were detected in the mothers or in their babies. All newborns are thriving normally, in a follow-up that lasted 3 to 6 months after delivery. It is concluded that UDCA appears to be safe when administered in late pregnancy; its promising efficacy in the treatment of intrahepatic cholestasis of pregnancy should now be confirmed in controlled clinical trials.

Adult↗
PubMed1990

Epidemic transmission of enterically transmitted non-A, non-B hepatitis in Mexico, 1986-1987.

Outbreaks of acute hepatitis occurred in Huitzililla and Telixtac, two rural villages 70 miles south of Mexico City, Mexico, in late 1986. The first outbreak began in Huitzililla in June of that year, 1 month after the start of the rainy season. A census revealed 94 icteric case subjects, for an attack rate of 5%; two women died. Attack rates were higher for persons older than 15 years (10%) than for younger persons. A case-control study showed that illness was highly associated with water-related factors. The second outbreak began in August 1986 in Telixtac. There were 129 case subjects, for an attack rate of 6%; one woman died. Epidemiologic findings were similar to those in Huitzililla, except that most disease transmission was not linked to unsafe water sources. None of 62 case subjects in Huitzililla and only 2 of 53 case subjects in Telixtac tested had serological evidence for recent infection with hepatitis A or B. Two of eight stool samples from Huitzililla and one of the eight stool samples from Telixtac were positive by immune electron microscopy for 32- to 34-nm viruslike particles similar to those seen in cases of enterically transmitted non-A, non-B hepatitis from Asia. To our knowledge, these investigations document for the first time the epidemic transmission of enterically transmitted non-A, non-B hepatitis virus in the Americas.

Acute Disease↗
PubMed1990

Effects of Ca2+ entry blockers on CaCl2-, KCl- and noradrenaline-induced contractions of goat cerebral arteries.

The effects of three Ca2+ entry blockers, nicardipine, nimodipine and verapamil, on CaCl2-, KCl- and noradrenaline-induced contractions were examined in isolated goat middle cerebral artery. The relationship between the effects of Ca2+ entry blockers and the extracellular Ca2+ dependence of the contractions was also examined. In 'nominally' Ca2(+)-free medium, addition of CaCl2 induced concentration-dependent contractions of previously depolarized arteries. Withdrawal of Ca2+ from the extracellular medium caused strong inhibition of the KCl- and noradrenaline-induced arterial contractions. Addition of EGTA to the Ca2(+)-free medium almost abolished the noradrenaline-response but did not increase the inhibition of the KCl-induced contractions. The Ca2+ entry blockers induced concentration-dependent relaxation of the precontracted arteries (100 mM KC1) with the following order of potency: nimodipine greater than nicardipine greater than verapamil. The CaCl2-, KCl- and noradrenaline-induced contractions were depressed in a concentration-related manner by nicardipine, nimodipine and verapamil. Dihydropyridines showed a greater inhibitory effect than verapamil. These results show that Ca2+ entry blockers are able to inhibit the contractile responses of goat cerebral arteries to KCl and noradrenaline, an effect which may be explained by the strong dependence of both responses on extracellular Ca2+.

Animals↗
PubMed1990

Bronchial migration of pulmonary arterial coil.

Transcatheter embolization was performed with stainless steel coils in a patient with bilateral pulmonary arterial aneurysms of unknown etiology. After a successful initial procedure, endobronchial migration of one of the coils was found which required surgical treatment. Indications of embolization and different types of materials are discussed.

Adolescent↗
PubMed1990

Heterogeneity of P2-purinoceptors in brain circulation.

The existence of P2-purinoceptors in the cerebrovascular bed was examined by testing the effects of ATP and its stable analog, alpha, beta-methylene-ATP, on CBF in the unanesthetized goat as well as on isometric tension in isolated goat middle cerebral artery. When injected directly into the cerebral circulation, ATP increased and alpha, beta-methylene-ATP decreased CBF. Indomethacin did not modify either of these effects. The vasoconstrictor action of alpha, beta-methylene-ATP was reduced by nicardipine. "In vitro," both ATP and alpha, beta-methylene-ATP contracted the cerebral arteries at resting tone, but the analog was more potent than ATP. Repeated application of alpha, beta-methylene-ATP as well as indomethacin significantly reduced the ATP-induced contractions. Nicardipine inhibited both the alpha, beta-methylene-ATP- and the ATP-induced contractile response. In preconstricted arteries, ATP produced relaxation and alpha, beta-methylene-ATP induced further contraction. The relaxant response to ATP was not modified by indomethacin. These results show the existence of two subtypes of P2-purinoceptors in brain circulation: P2x, more sensitive to alpha, beta-methylene-ATP than to ATP, which elicits cerebral vasoconstriction; and P2y, sensitive to ATP, which elicits cerebral vasodilation.

Adenosine Triphosphate↗
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↗