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Biomedical subjects

A Garrido

Publications and source records attributed to A Garrido.

At least 55 records · Page 3Linked to original sources
PubMed1996

High frequency of altered HLA class I phenotypes in invasive breast carcinomas.

We studied 105 tumor samples obtained from patients diagnosed as having breast carcinomas for HLA class I and II (DR) antigen expression, using a panel of mAbs defining HLA-monomorphic, locus-specific and allele-specific determinants. Peripheral blood lymphocytes from patients were also typed for HLA alleles. The results indicated total HLA class I losses in 55 patients (52.3%), HLA-A locus losses in four patients (3.8%), HLA-B locus losses in eight patients (7.6%), and A, B, locus losses in 10 patients (9.5%). The remaining 28 patients whose tissues reacted positively with monomorphic- and locus-specific mAbs were tested for HLA allelic losses using several anti-HLA mAbs defining A2, A3, A9, B8, B12, etc. Of these 28 patients, 16 (57%) showed one or more losses of HLA reactivity. These results indicated that in 88.5% of patients we detected a particular HLA-altered tumor phenotype. The downregulation of HLA class I antigens in breast carcinomas may thus be more frequent than previously reported, and patients without HLA class I downregulation may be the exception rather than the rule. It cannot be ruled out that HLA alterations are present in some of the 12 patients with an apparently normal HLA phenotype, as some HLA alleles could not be studied because of the lack of appropriate mAbs. These HLA alterations could represent an important step associated with tumor invasion, conferring to the tumor cells the ability to escape from T-lymphocyte recognition.

Antibodies, Monoclonal↗
PubMed1996

[The excretion of free cortisol in the urine in healthy children and in asthmatics treated with long-term inhaled glucocorticoids].

OBJECTIVE: To assess urinary free cortisol (UFC) excretion in 24 hour urine samples collected from asthmatic children treated with inhaled glucocorticoids (IGC). PATIENTS AND METHODS: A retrospective cohort study was performed on a group of 358 children between the ages of 3 and 14 years. The children were divided into two groups, a normal population (n = 108) and an asthma group (n = 250). These children were treated uninterruptedly with IGC (mean dose 676 micrograms/day) during 17 +/- 8 months with budesonide (n = 221) or beclomethasone (n = 29) in dry powder (n = 167) or MDI with spacer chamber (n = 83). We considered the 24 hour urine sample valid when creatinine levels in blood and urine, as well as creatinine clearance, were normal. We determined UFC with a specific direct radioimmunoassay after cortisol extraction with dichloromethane. We performed a short ACTH test to assess the subnormal adrenocortical function when UC excretion in AG was less than -1SD. RESULTS: UFC excretion was 81.98 +/- 32.12 nmol/m2/day in the asthma group. There was no correlation between UFC and the mean dose of IGC, total dose given, device used for inhalation, time of treatment or oral glucocorticoid series. The subgroup treated with beclomethasone presented UF rates lower than the subgroup treated with budesonide. Except for two cases, the ACTH test performed in the AG had normal adrenocortical responses. CONCLUSION: 1) We established the normal values for UFC excretion in our pediatric population. 2) The long term asthma treatment with glucocorticoids at mean doses of 650 micrograms l/m2/day decrease physiologically the UFC excretion since the adrenocortical response remains within the normal range.

Administration, Inhalation↗
PubMed1995

Continuous prazosin administration in cirrhotic patients: effects on portal hemodynamics and on liver and renal function.

BACKGROUND & AIMS: Hepatic vascular resistance is influenced by alpha-adrenergic tone. The aim of this study was to investigate the effects of continuous blockade of alpha-adrenoceptors with prazosin on hemodynamics, liver function, and renal function and whether the association of propranolol or furosemide enhances the portal pressure lowering effect of prazosin. METHODS: Cirrhotic patients with portal hypertension were studied at baseline and after a 3-month course of prazosin (n = 18) or placebo (n = 10). RESULTS: No changes were observed in the placebo group. Prazosin decreased the hepatic venous pressure gradient (HVPG) while increasing hepatic blood flow. Liver function improved as shown by an increase in hepatic and intrinsic hepatic clearances of indocyanine green and galactose elimination capacity. A significant reduction in mean arterial pressure and systemic vascular resistance was associated with increases in plasma renin activity and aldosterone concentration and a decrease in glomerular filtration rate. The plasma volume increased significantly, and 6 patients developed edema. The association of propranolol (n = 8) but not furosemide (n = 7) to prazosin increased the reduction in HVPG and attenuated the increase in plasma renin activity. CONCLUSIONS: In cirrhotic patients, continuous prazosin administration reduces portal pressure and improves liver perfusion and function but favors sodium and water retention. The association of propranolol enhances the decrease in portal pressure, suggesting a potential benefit from this combined therapy.

Adrenergic alpha-Antagonists↗
PubMed1995

A new methodology to solve the problem of characterizing 2-D biomedical shapes.

In this paper, a new approach to solve the problem of characterizing 2-D biomedical shapes is introduced. Two-dimensional biomedical contours are described through a 'degrees of smoothing' vector in which each component determines the proper degree of detail for representing each curve part isolating a single structure. A segmentation process is designed based on a clustering procedure applied to vectors of texture measures which are obtained from the graph of curvatures. To solve the problem of characterizing biomedical shapes, a suitable interpolation procedure between the most outstanding perceptual points from the smoothed contours is given.

Algorithms↗
PubMed1994

Increased IgM B cell differentiation lymphokine production by T lymphocytes from patients with primary biliary cirrhosis.

Hypergammaglobulinemia, mainly due to increased serum immunoglobulin M concentrations, is a common and distinctive feature of primary biliary cirrhosis. T-B cell cooperation plays a pivotal role in the regulation of immunoglobulin secretion. In this paper, the production of regulatory B lymphokines by T cells, as well as the functional response of B lymphocytes to these molecules, was investigated in patients with primary biliary cirrhosis. T cells from patients with primary biliary cirrhosis have an enhanced ability to produce lymphokines that regulate the proliferation of B cells and their differentiation to immunoglobulins G- and M-secreting cells. In contrast, the cellular production of lymphokines involved in the induction of immunoglobulin A-secreting cells was normal. Simultaneously, the proliferation and differentiation of purified B cells in response to stimulation with surface immunoglobulin ligands and lymphokines were normal. These results suggest that the elevated serum levels of immunoglobulins M and G found in patients with primary biliary cirrhosis could be ascribed to an enhanced lymphokine-mediated T-B cooperation.

Adult↗
PubMed1994

Hemodynamic effects of alpha-adrenergic blockade with prazosin in cirrhotic patients with portal hypertension.

This study was aimed at investigating whether the blockade of alpha 1-adrenergic receptors could reduce portal pressure in cirrhosis. Splanchnic and systemic hemodynamics were measured in 12 cirrhotic patients with esophageal varices at baseline and 1 hr after oral administration of 2 mg of prazosin (acute study). Measurements were repeated in 10 of these 12 patients after a 3-mo course of 5 mg/12 hr of prazosin (long-term study). Short-term prazosin significantly lowered the hepatic venous pressure gradient from 20.1 +/- 1.3 to 14.4 +/- 0.9 mm Hg (-25.7%) (p < 0.01), and chronic prazosin reduced it to 16.5 +/- 1.3 mm Hg (-19.1%) (p < 0.01). Hepatic blood flow was increased, thus changes in the hepatic venous pressure gradient resulted from a reduction in the estimated hepatic vascular resistance. Reductions in hepatic venous pressure gradient achieved after short-term and long-term prazosin were not significantly different. Reductions in mean arterial pressure and systemic vascular resistance were significantly greater after short-term than after long-term prazosin. Long-term prazosin was associated with significant increases in hepatic and intrinsic hepatic clearances of indocyanine green. This therapy also led to an increase in pulmonary capillary pressure (+ 28.6%, p < 0.05) and body weight (+ 3.06%, p < 0.01) and a decrease in hematocrit (-6.1%, p < 0.05) and urinary sodium excretion (-22.6%, p < 0.05). In contrast, there were no hemodynamic changes in a group of six cirrhotic patients receiving placebo. In cirrhotic patients, short-term prazosin lowers portal pressure by decreasing hepatic vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1994

Biochemical bases of the pharmacological action of the flavonoid silymarin and of its structural isomer silibinin.

The flavonoid silymarin and one its structural components, silibinin, have been well characterized as hepato-protective substances. However, little is known about the biochemical mechanisms of action of these substances. This review deals with recent investigations to elucidate the molecular action of the flavonoid. Three levels of action have been proposed for silymarin in experimental animals: a) as an antioxidant, by scavenging prooxidant free radicals and by increasing the intracellular concentration of the tripeptide glutathione; b) regulatory action of the cellular membrane permeability and increase of its stability against xenobiotic injury; c) at the nuclear expression, by increasing the synthesis of ribosomal RNA by stimulating DNA polymerase I and by exerting a steroid-like regulatory action on DNA transcription. The specific hepatoprotective action of silibinin against the toxicity of ethanol, phenylhydrazine and acetaminophen is also discussed. It is suggested that the biochemical effects observed for the flavonoid in experimental models may settle the basis for understanding the pharmacological action of silymarin and silibinin.

Animals↗
PubMed1993

Biochemical changes during the preservation stage of ripe olive processing.

The influences of initial sodium chloride (6% and 0% w/v in tap water) and acetic acid concentrations (0.3%, and 0.6% v/v), use of starter culture, and aerobic versus anaerobic conditions on the biochemical changes that take place throughout the preservation stage of ripe olive processing were investigated. Glucose, fructose and sucrose were completely consumed during preservation. Mannitol and malic acid were metabolized only in the presence of lactic acid bacteria or oxidative yeast (aerobic treatment). The main metabolites produced were lactic and acetic acid in aerobic or anaerobic treatments inoculated with Lactobacillus plantarum. Methanol and ethanol were present in all the brines although in a lower concentration when conditions were aerobic. Thus, induced lactic fermentation led to the most efficient utilization of carbohydrates and yielded the most suitable physicochemical characteristics for ripe olive preservation.

Chemical Phenomena↗
PubMed1993

Different glutathione redox status and lipid peroxidation in the cortex and the medulla of the rat kidney subjected to ischemia-reperfusion stress.

When the rat kidney is subjected to ischemia and reperfusion, changes in glutathione content and in lipid peroxidation are produced in the cortex and in the medulla. The cortex shows a decrease in the glutathione content and a higher sensitivity to development of lipid peroxidation, the medulla being less affected. Reperfusion restores the glutathione concentration of the cortex during the first hours of reflow. The lipid peroxidation observed in the cortex and the medulla during reperfusion is higher than in ischemia. The protective role of glutathione and the response of the cortex and the medulla to ischemia-reperfusion injury are discussed.

Animals↗
PubMed1993

Changes in the antioxidant capacity of blood plasma are produced after the ingestion of high doses of fish oil.

Blood plasma shows antioxidant capacity (AOC) due to a number of molecules possessing antioxidant activity. Plasma AOC of young and aged rats fed high doses of fish oil and fish oil + dl-alpha tocopherol was assayed. It was observed that only young rats fed fish oil (with or without antioxidant) show a significant increase in their plasma AOC when compared with controls and with the aged ones. It is suggested that increased AOC results from an adaptive response of animals to the potential risk of oxidative stress due to the increase of membrane polyunsaturation after fish oil ingestion.

Aging↗
PubMed1993

Fluoride absorption from disodium and calcium monofluorophosphates from the gastrointestinal tract of rats.

The contribution of the stomach and the small intestine to the in vivo absorption of fluoride from disodium and calcium monofluorophosphates was studied in comparison with that observed when sodium fluoride is given to rats. In vitro experiments with ligated duodena were also carried out. Fasted rats were given orally 50 micrograms of fluoride in pH 6.3 buffered disodium monofluorophosphate solutions with and without 50 mM added calcium. The same amount of fluoride was administered in the form of an aqueous sodium fluoride solution. In both cases the fluoride solutions contained trace amounts of (14C)-labeled polyethyleneglycol as a marker for the study of water movement through the gastrointestinal tract. Results obtained show the small intestine as the main site of the absorption of the studied compounds. Under the fasting conditions employed in our study gastric absorption was in turn, almost negligible. While fluoride transport from sodium fluoride seems to occur through a difussion mechanism, disodium and calcium monofluorophosphates appear to be absorbed through a more complex mechanism involving an enzymatic hydrolysis and an independent and possibly parallel direct tissue absorption of a soluble, neutral calcium monofluorophosphate complex.

Administration, Oral↗