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Biomedical subjects

M Castro

Publications and source records attributed to M Castro.

At least 235 records · Page 13Linked to original sources
PubMed1990

Beta-lipotropin/adrenocorticotropic hormone responses to corticotropin releasing hormone, hypoglycemia, metyrapone and dexamethasone in normal human subjects.

1. The possible correlation between secretions of adrenocorticotropic hormone (ACTH) and of beta-lipotropin (beta-LPH), two pro-opiomelanocortin (POMC)-derived peptides, was investigated in 27 normal subjects under basal conditions (circadian rhythm), after the administration of 1 mg dexamethasone and in tests involving acute (human corticotropin releasing hormone, hCRH, and insulin tolerance test, ITT) and chronic (metyrapone) stimulation. 2. All subjects presented circadian rhythm and an operating negative feedback mechanism. Plasma ACTH and beta-LPH concentrations were correlated in all tests. The increase in ACTH and beta-LPH levels after hCRH was lower than that detected after ITT, though both increases were more discrete than those detected after stimulation with metyrapone. 3. The data suggest that, under hypoglycemic conditions, ACTH and beta-LPH secretion involves other POMC secretagogues in addition to endogenous CRH. The nature of these factors remains undefined. The greater efficacy of metyrapone treatment in elevating ACTH and beta-LPH levels is most likely mediated by sustained reduction in cortisol production and interruption of the rapid steroid feedback on the pituitary. 4. The molar peak ratios of the acute tests, which were similar to one another, differed from the peak ratio obtained during the metyrapone test, suggesting that corticotrophs may present pools with differentiated ACTH and beta-LPH content and release according to the type and/or duration of the stimulus.

Adrenocorticotropic Hormone↗
PubMed1990

[Changes in the prostanoid content and the population of endocrine cells in jejunal biopsies from celiac children].

Prostanoid content prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) and endocrine cells population were evaluated in jejunal biopsies from celiac children; findings were compared to active celiac patients on a challenge diet. Patients were divided as follows: Group A: 14 children with active untreated celiac disease; Group B: 7 celiac children on gluten challenge who had received diet therapy for the past 2 years; Group C: 8 normal control children. Jejunal biopsies were used for endocrine cell population measurement by immunocytochemistry, using a specific marker (chromogranin), and for prostanoid radioimmunological evaluation. The quantitative assessment of the endocrine cell population in Groups A and B revealed a significantly higher number of endocrine cells (20 +/- 11.5; 18.4 +/- 9.8 n. cell/visual field respectively) compared to Group C (8.44 +/- 2.3 n. cell/visual field) (p less than 0.05). In the jejunal extract the PGE2 content (341.8 +/- 82.3) ng/g) for Group A biopsies was significantly higher than that of Group C biopsies (93 +/- 23 ng/g) (p less than 0.05. The PGE2 content (69.4 +/- +13.2 ng/g) for Group B did not show any statistically significant change. In contrast, TxB2 content in jejunal biopsies from all three groups was not significantly different.

APUD Cells↗
PubMed1990

[Intestinal absorption of vitamin E in children with atrophy of the jejunal mucosa].

The intestinal absorption of vitamin E is often thought to be closely correlated to that of fatty acids, but the biochemical mechanisms involved in the process are still not clear. For this reason, the present study aimed to assess the absorption of triglycerides and vitamin E, following oral administration, in 11 children with suspected malabsorption syndromes. Intestinal biopsy in 9 children showed the presence of a flat mucosa, whereas no changes were present in 2 patients. The results confirm the inverse correlation between the absorption of triglycerides and vitamin E, as if tocopherols used an independent system of transport. These findings contrast with those reported in the literature perhaps due to the low level of precision of colorimetric techniques previously used to assay vitamin E.

Atrophy↗
PubMed1990

Survival in cystic fibrosis: preliminary report from an Italian multicenter study.

An Italian multicenter study has been carried out in order to obtain data on survival and prognostic factors in CF. We report data from four CF Centers: Milan, Neaples, Cagliari, Rome, Anagraphic data, mode of presentation and of diagnosis were collected, using CFDB database, from 536 CF pts. 39 pts had meconium ileus (7.3%); 269 (50%) were diagnosed before 12 months of age. 27 pts were lost to follow-up (5%); and 65 pts died (12%). Statistical analysis was performed by Kaplan-Meier survival curves compared by Logrank test.

Adolescent↗
PubMed1989

[Malabsorption syndrome caused by Giardia lamblia in gastrectomized patients].

We report three adult patients with gastrectomy who had malabsorption caused by Giardia lamblia. Type II gastrectomy had been carried out in the three patients several years before, and the clinical presentation was similar: chronic diarrhea with malabsorption. A remarkable fact was that the search for parasites in feces was repeatedly negative in two patients, the protozoon being identified in the intestinal biopsy samples. In the third case, the diagnosis was made by the visualization of Giardia cysts in the feces.

Animals↗
PubMed1988

Studies with etofibrate in the rat. Part I: Effects on glycerol, free fatty acid and triacylglycerol metabolism.

Etofibrate is the 1,2-ethandiol diester of clofibric acid and nicotinic acid that decreases circulating levels of triacylglycerols and cholesterol. To understand the mechanism by which the drug affects plasma triacylglycerols, normolipemic rats were treated daily with 300 mg of etofibrate/kg body weight or with the medium by a stomach tube. They were decapitated on the 10th day, and showed lower levels of plasma beta-hydroxybutyrate, glycerol, free fatty acids (FFA), total triacylglycerols and cholesterol and VLDL triacylglycerols and cholesterol, whereas glucose and RIA-determined insulin levels were unmodified. Epididymal fat pad pieces from etofibrate-treated rats incubated in vitro released more glycerol but the same amount of FFA to the medium, and had greater uptake of [U-14C]glycerol for [14C]acylglycerol formation. In the presence of heparin, they also showed an enhanced release of lipoprotein lipase activity to the medium. The disappearance from plasma of intravenously administered [1-14C]palmitate was faster in the etofibrate-treated rats, and although they showed a decrease in 14C-esterified fatty acids of neutral lipids in both liver and plasma VLDL, there was an increase in liver 14C-labelled water-soluble components. After intravenous [U-14C]glycerol administration, there was a decrease in plasma VLDL [14C]acylglycerol and [14C]glucose and in liver [14C]acylglycerol, but an increase in plasma [14C]lactate. In the liver, etofibrate treatment heightened the cytosolic glycerol-3-phosphate dehydrogenase activity and the total carnitine concentration, whereas it reduced triacylglycerol and cholesterol concentrations. It is proposed that etofibrate enhances the reesterification of fatty acids and glycerol in adipose tissue, which, together with its augmented lipoprotein lipase activity, may facilitate the clearance of circulating triacylglycerols. These effects may act concomitantly with the decreased synthesis of triacylglycerols, secondary to the increased utilization of their precursors, acyl-CoA and glycerol-3-phosphate, in other pathways, causing the reduction of plasma VLDL triacylglycerols produced by etofibrate treatment.

Adipose Tissue↗
PubMed1988

Hemodynamic effects of nitrendipine on systolic ventricular function, diastolic ventricular function, and peripheral circulation in essential hypertension.

Twenty patients (aged 33-60 years) with mild to moderate essential hypertension were studied to assess systolic ventricular function, diastolic ventricular function, and peripheral hemodynamic changes induced by nitrendipine during rest and effort, comparing the acute and chronic treatment phases. We used a randomized, placebo-controlled, double-blind, crossover protocol in the acute phase and a paired, placebo group controlled study, with 20 mg single oral daily dose for a 3-week treatment period (chronic phase). The cardiac and peripheral hemodynamic parameters were quantified by noninvasive radionuclides techniques. During acute treatment, peripheral hemodynamics showed a predominantly arteriolar vasodilatory effect with a significant fall in the previously elevated forearm vascular resistance values (-38%, p less than 0.01) and an important increase in forearm blood flow (+49%, p less than 0.01) without any changes in venous capacity. Simultaneously, nitrendipine produced a significant drop in total peripheral resistance (-36%, p less than 0.01), systolic blood pressure (-13%, p less than 0.01), and diastolic blood pressured (-17%, p less than 0.01). The sudden reduction in left ventricular (LV) afterload caused a reflex increase in heart rate (HR) (+12%, p less than 0.01), cardiac index (+37%, p less than 0.01), LV ejection fraction (+17%, p less than 0.01), and peak ejection rate, with an important decrease in LV end systolic volume (-30%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Characterization of amino acid transport during erythroid cell differentiation.

We have studied the changes in amino acid transport in fetal erythroid cells isolated from rat fetal liver at different gestation days. Our results show that System A transport as measured by the Na+-dependent uptake of 2-(methylamino)isobutyric acid (MeAIB) was conspicuous at day 13 but virtually disappeared between days 16 and 18. In contrast, the activity of System ASC measured by the Na+-dependent uptake of MeAIB-insensitive threonine uptake increased after day 14 and was optimal between days 16 and 18. This transport system regressed in activity with further maturation, but remained conspicuously saturable in the matured red blood cell. Interestingly, the newly discovered Na+-independent System asc (Vadgama, J. V., and Christensen, H.N. (1985) J. Biol. Chem. 260, 2912-2921), selective for the uptake of test substrates threonine, serine, and alanine, was present in these erythroid cells. Its activity increased during gestation days 16-18. System L transport was present simultaneously with the Na+-independent System asc. As we had previously demonstrated for the pigeon red blood cell, these two transport systems are kinetically independent as confirmed with inhibition studies and the special selectivity of System L to trans stimulation. Tryptophan uptake could be attributed predominantly to System L, as also observed for the nucleated pigeon red blood cells and certain other cells. Arginine showed its familiar Na+-independent mode of uptake as a cation throughout the interval of study. An exceptional Na+-dependent component of arginine uptake emerged after day 14, peaked at day 18, and then disappeared on further maturation of the erythroid cell.

Amino Acids↗
PubMed1987

Prevalence of antibodies to the human immunodeficiency virus in Dominicans and Haitians in the Dominican Republic.

Few patients with the acquired immunodeficiency syndrome have been reported in the Dominican Republic, although they share the island of Hispaniola with Haiti, which has numerous cases. Prevalence of antibodies to the human immunodeficiency virus in serum samples from Dominicans tested from 1983 through 1985 was low in comparison with that of clinically healthy Haitians working in the country. The Haitians, who gave no history of any known risk factor, had a seroprevalence to the virus of more than 10%. Only Dominican homosexuals had a high rate of seropositivity (19%); intravenous drug abusers, healthy heterosexuals, female prostitutes, and other subgroups had virtually no evidence of antibodies to the human immunodeficiency virus. These results suggest that passage of the acquired immunodeficiency syndrome retrovirus between populations in two countries on the same island did not occur except by known risk practices. They emphasize that the extent of viral transmission in Haiti is greater than that observed in the Dominican Republic.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Toxic-oil syndrome: case reports associated with the ITH oil refinery in Sevilla.

Toxic-oil syndrome (TOS), a new disease that occurred in epidemic form in Spain in 1981, has been associated with the ingestion of unlabelled oil bought principally from travelling salesmen. Chemical analysis of oils taken from ill families has shown them to consist of varying proportions of different vegetable oils and animal fats, often showing chemical evidence of prior treatment with aniline. We investigated the unusual circumstances surrounding the reported occurrence of three TOS cases in two families in Sevilla, a city located far away (approximately 300 km) from the group of 14 provinces in central and northwestern Spain where 99% of the TOS cases occurred. Each case we investigated fitted the clinical picture of TOS and was not consistent with any other diagnosis. Illness apparently occurred as a result of ingestion of oil taken from the ITH oil refinery in Sevilla, a plant in which rapeseed and grapeseed oils were refined for the distributing firm through which oil bearing the causative agent of TOS is thought to have entered the market. These data provide further strong support for the hypothesis that food oil was the vehicle by which the aetiological agent of TOS was transmitted. Because ingestion of refined denatured rapeseed oil was most closely associated with the illness in time, the TOS agent was probably contained initially in this type of oil. The agent very probably entered later oil mixtures through such contaminated rapeseed oil.

Adult↗
PubMed1987

Prostanoids in jejunal biopsy specimens of celiac children with active disease and on challenge diet. Radioimmunologic evaluation.

Prostanoid generation (prostaglandin E2 and thromboxane B2) in jejunal biopsy specimens from celiac patients was evaluated, comparing celiac patients with celiac patients on challenge diet and controls. Generation of prostaglandin E2 in jejunal specimens from 14 children with active celiac disease was significantly higher (341.8 +/- 82.3 ng/g; mean +/- SEM) than that from 7 celiac patients on gluten challenge diet (69.4 +/- 13.2 ng/g) or 8 normal children (92 +/- 23 ng/g) (p less than 0.05). In contrast, thromboxane B2 generation in jejunal specimens from all three groups did not show any statistically significant variation. Our results indicate that prostaglandin E2 generation is not merely related to the activity of clinical symptoms, since patients receiving gluten challenge had prostaglandin E2 levels that did not differ from those of controls.

Adolescent↗
PubMed1986

Monkey erythropoietin gene: cloning, expression and comparison with the human erythropoietin gene.

The erythropoietin (Epo) gene from Cynomolgus monkeys has been isolated from a kidney cDNA library using mixed 20-mer oligodeoxynucleotide probes. The gene encodes a 168 amino acid (aa) mature protein with a calculated Mr of 18,490 and a presumptive signal peptide of 24 aa. The Epo gene, when transfected into Chinese hamster ovary (CHO) cells, produces a glycosylated protein with an apparent Mr of 34,000. The expressed product is biologically active in vivo. The monkey gene exhibits 92% and 94% homology to the human gene at the aa and nucleotide sequence levels, respectively. When compared with the human Epo, monkey Epo has an additional 3-aa residue at the N terminus of the mature protein and a deletion of an internal lysine residue.

Amino Acid Sequence↗
PubMed1986

Anaphylatoxin C5a generation and dialysis-induced leukopenia with different hemodialyzer membranes.

Leukocyte counts and plasma C5a anaphylatoxin levels were studied during hemodialysis in patients using Cuprophan, polycarbonate and polyacrylonitrile membrane dialyzers. Cuprophan induced a marked leukopenia with significant plasma C5a generation. Polycarbonate promoted the same trend of changes in both parameters but significantly less pronounced, while polyacrylonitrile did not affect leukocyte counts nor plasma C5a levels. These data suggest that complement-derived C5a generation may be an important factor in the mechanism of hemodialysis-induced leukopenia.

Acrylic Resins↗