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Biomedical subjects

V Alvarez

Publications and source records attributed to V Alvarez.

At least 127 records · Page 7Linked to original sources
PubMed1985

Vaccination against hepatitis B in renal dialysis units: short or normal vaccination schedule?

Three I.M. injections of hepatitis B vaccine (Merck Sharp & Dohme) were administered, according to the recommended schedule (0, 1, 6 mos), to seronegative individuals of one renal dialysis unit (33 patients, 58 health care personnel) and, according to a shorter regimen (0, 1, 3 mos), in another unit of similar characteristics (30 patients, 53 health care personnel). Staff members and renal patients received, respectively, 20 y 40 mcg of vaccine per injection. In the early vaccination phase, the two regimens did not lead to a difference in seroconversion rates nor in anti-HBs titers. After a 9-month surveillance, lower seroconversion rates, although not significant, were observed with the accelerated regimen among staff members (84.2%) and renal patients (79.2%) as compared with 93% and 87.5%, respectively, following the normal schedule. At the same time, anti-HBs titers were significantly lower (p less than 0.001) in the staff (316 RIA U) and patients (93 U) vaccinated according to the short regimen than in their respective counterparts (4196 and 1047 U) assigned to the normal schedule. A fourth dose of vaccine given to subjects with low and no anti-HBs titers significantly increased seroconversion and anti-HBs levels, although with little success among the former non-responders.

Adult↗
PubMed1984

A new assay for factors that regulate the synthesis of granulocyte differentiation proteins in vitro.

Morphological and molecular aspects of granulocyte differentiation can be studied concomitantly using liquid cultures of immature granulocytes in conjunction with a newly developed high-performance liquid chromatographic (HPLC) assay for differentiation proteins. Immature granulocytes, isolated from guinea pig bone marrow by Ficoll density centrifugation, were placed in liquid cultures and incubated for periods up to 1 week. In the presence of 10% dialyzed, normal guinea pig serum, these cells were almost all converted to mature granulocytes, whereas at serum concentrations below 1% mostly macrophages were formed. Cell multiplication does not appear to be necessary for granulocyte maturation in this culture system. The data also show that morphological maturation in vitro is accompanied by the formation of all the major membrane and secondary granule differentiation proteins detected by the HPLC assay in extracts of mature granulocytes formed in vivo. The techniques described here should facilitate the isolation and purification of the factors in normal serum that control the induction of synthesis of these differentiation markers.

Animals↗
PubMed1983

Presence in normal human urine of a hypotensive and platelet-activating phospholipid.

Urine from normotensive volunteers and patients with systemic lupus erythematosus glomerulonephropathy was sequentially concentrated by negative-pressure ultrafiltration, dialyzed against distilled water, and extracted into the chloroform phase of a mixture of organic solvents(chloroform:methanol:water, 1:1:0.9 vol/vol). The lipid fraction was further purified by thin-layer chromatography on silica gel plates using neutral, acidic, and basic mixtures of organic solvents and it was then tested for its ability to induce the release of [3H]serotonin from rabbit platelets. All of the samples contained a platelet-activating moiety similar to a synthetic platelet-activating factor (PAF-acether) on the basis of its chromatographic behavior, resistance to the pretreatment of platelets by 10(-6) M indomethacin, and loss of activity by alkaline methanolysis or treatment by phospholipases A2, C, and D. Cross-densensitization experiments between synthetic PAF-acether and the urine factor showed that both compounds act on platelets through the activation of the same putative receptor. Further, the urine factor induced hypotension when intra-arterially injected in normotensive rats, and this activity was also abrogated by alkaline methanolysis. In summary, these data provide evidence of the presence in normal human urine and, probably, of the release by the kidney of a lipid factor with platelet-activating and hypotensive activity whose general structure seems to be alkyl-acyl-glyceryl-phosphorylcholine and, therefore, is similar to the structure of the inflammatory mediator PAF-acether and the antihypertensive polar renomedullary lipid.

Animals↗
PubMed1982

Vascular actions of synthetic PAF-acether (a synthetic platelet-activating factor) in the rat: evidence for a platelet independent mechanism.

Since rat platelets fully responsive to thrombin and collagen did not respond by releasing 3H-serotonin with up to 10 micrograms/ml of synthetic PAF-acether, the rat, contrariwise to the rabbit, was considered to be an appropriate model to study the actions of PAF-acether not mediated through the activation of platelets and the subsequent release of their inflammatory mediators. We developed an experimental approach using 57Co and 113Sn radiolabeled microspheres to assess the effect of PAF-acether on cardiac output, peripheral vascular resistance, and regional flows and resistance. The effect on vascular permeability and blood volume was studied by measuring the clearance of 125I-HSA and the variations of the hematocrit. A significant fall in blood pressure and peripheral vascular resistance was found with doses of PAF-acether ranging from 0.05 to 5 micrograms. Moreover, the higher doses of PAF-acether also induced a marked depletion of blood volume. A significant fall in spleen, coronary, and kidney output, but not in cardiac output, was also found. Our data show that PAF-acether, by itself, induces a drop in peripheral vascular resistance and, at higher doses, also in circulating volume, accounting for both by the hypotensive effect. The redistribution of cardiac output seems to be the expression of a nonuniform action of the compound on the vascular resistance of the different organs.

Animals↗
PubMedDate not supplied

[Molecular changes in epidermoid carcinoma of the oropharynx].

In most of the studies about molecular alterations in squamous cell carcinomas of the head and neck there is not distinction between the different subsites of this area. The objective of this study is to describe the molecular alterations in squamous cell carcinomas of the oropharynx. Twenty-nine oropharyngeal carcinomas, with a minimum follow-up of 36 months, were studied. The molecular alterations analyzed were: the amplification of 11q13 region (in the 29 cases), and the MYC and ERBB1 oncogenes (in 22 cases); the integration of Human Papillomavirus (HPV) types 6b and 16 (in 22 cases); the loss of heterozygosity (LOH) of p53 and N-acetyltransferase-2 (NAT2) gene (in 12 and 13 informative cases, respectively); and the cellular DNA content (in 13 cases). The most frequent alterations found were the LOH at p53 (67%), and NAT2 (54%) locus, followed by 11q13 amplification (49%). ERBB1 amplification was found in 14% of the cases, and MYC amplification only in one (5%). Integration of the HPV was found in 23% of the cases. Nine (69%) of the 13 analyzed cases were aneuploid. The only alteration with a prognostic significance was 11q13 amplification that showed a tendency to be associated with a higher frequency of nodal metastases and tumor recurrence.

Adult↗
PubMedDate not supplied

Lack of association between polymorphisms of the coagulation factor VII and myocardial infarction in middle-aged Spanish men.

In order to determine the role of two polymorphisms in the factor VII gene (R353Q and intron 7 hypervariable region) in the susceptibility to develop early myocardial infarction, a total of 175 patients with acute myocardial infarction aged 50 years or less (mean age 41+/-7 years) and 200 controls (average age 42+/-6) without cardiovascular disease were genotyped for these polymorphisms. Gene and genotype frequencies did not differ between patients and controls. Although the 353-QQ genotype was at a higher frequency among controls (4%) compared to patients (1%), the difference did not reach statistical significance. Carriers of the H7-allele (intron 7 polymorphism) were at a slightly higher frequency among patients (51 vs. 43%; P=0.19; OR=1.36; 95% CI=1.09-1.70). Our data suggest a lack of association between both polymorphisms in the factor VII gene and early myocardial infarction in our population.

Adult↗
PubMedDate not supplied

Obesity modifies the relationship between ambulatory blood pressure and natriuresis in children.

BACKGROUND: The objective in the present study was to evaluate if obesity beginning in the first two decades of life influences the relationship between ambulatory blood pressure and urinary sodium excretion. DESIGN AND METHODS: Eighty-five obese and 88 non-obese children aged 3-19 years were included in the study. For each subject, a 24h ambulatory blood pressure monitoring and a complete urine collection were simultaneously performed according to the protocols designed. The averages of ambulatory blood pressure and of the urinary excretion rates for sodium, potassium and creatinine were calculated separately for 24-h, awake and sleep periods as defined by a mini-diary. RESULTS: Weight and sodium excretion are directly associated with systolic blood pressure; however, the relationship between blood pressure and sodium excretion seems to be modified in obese children as compared to controls. The interaction between sodium excretion and weight was negative indicating that the rate of change of systolic blood pressure by sodium unit is smaller for the obese than for the non-obese, even though at the same urinary sodium excretion level the obese children had higher ambulatory systolic blood pressure. CONCLUSIONS: Obesity during the first two decades of life seems to restrict sodium excretion, leading to higher blood pressure values. The capacity to excrete sodium seems to be heterogeneous, the lowest capacity being at the highest blood pressure values. Subsets of the obese, those with the lowest ability to excrete sodium, may be further protected by low sodium intake in order to prevent a rise in blood pressure.

Adolescent↗
PubMedDate not supplied

Obesity, body fat distribution, and ambulatory blood pressure in children and adolescents.

Obesity is a common disease with an ever-increasing prevalence and usually with late-onset consequences. If acquired during childhood, it tracks into adult life to some extent, and since the relationship between obesity and hypertension is well established in adults, obese children appear to be at particularly high risk of becoming hypertensive adults. In the authors' study, obese children seemed to have significantly higher casual and ambulatory blood pressure than nonobese children, except for nighttime diastolic blood pressure. The health effects of obesity may depend on the anatomic distribution of body fat, which in turn may be a better indicator of endocrinologic imbalance, environmental stress, or genetic factors than is fatness per se. Subjects with a higher waist-to-hip ratio or a larger waist, as an estimate of central obesity, tend to have higher blood pressure values even during childhood. Prevention of the onset of obesity in early life may be important to reducing the risk of coronary heart disease in later life.

Adipose Tissue↗
PubMedDate not supplied

[Sudden death in a normal heart. Idiopathic ventricular fibrillation. Review of the literature concerning one case].

Idiopathic ventricular fibrillation is that which is produced in the absence of structural cardiac disease and of other identifiable causes of ventricular fibrillation such as cardiotoxicity, electrolytical alterations or hereditary predisposition. The case of a healthy male, aged 37, who was asymptomatic until the day he was admitted to hospital where he showed numerous episodes of ventricular fibrillation without any previous triggering, is discussed. In the examination no cause was found to explain this, and an automatic defibrillator was implanted. The requirements for its diagnosis, risk stratification and the usefulness of the tests employed, as well as the treatments proposed are discussed.

Adult↗
PubMedDate not supplied

Rapidly induced modulation of beta-N-acetylglucosaminidase activity in pancreatic islets.

The aim of this work was to determine the possible rapid modulatory effect of glucose on the activity of pancreatic islet lysosomal enzymes. For this purpose, beta-N-acetylglucosaminidase and beta-galactosidase activities were measured in homogenates of isolated rat islets after a 5, 15, 30 or 60-min exposure to either 3.3 or 16.6 mM glucose. The enzyme activities were determined spectrofluorometrically by means of their respective 4-methylumbelliferyl derivatives as substrates. beta-N-acetylglucosaminidase activity measured in freshly isolated non-incubated islets was 5.482 +/- 0.281 mumol/mg protein/h at 37 degrees C. In islets incubated with 3.3 mM glucose, this activity dropped significantly after 5 min and remained almost constant until the end of the incubation period. In islets incubated with 16.6 mM glucose, beta-N-acetylglucosaminidase activity also decreased significantly at 5 min, and attained its lowest value after 15 min of incubation. After this interval, the activity began to recover and thereafter gained a value close to that measured in non-incubated islets by 60 minutes' time. Despite this ultimate recovery, the enzyme activities measured were significantly lower than those found in islets incubated with 3.3 mM glucose. beta-galactose activity in freshly isolated non-incubated islets was 0.515 +/- 0.094 mumol/mg protein/h at 37 degrees C. This value remained almost unchanged throughout the incubation period in the presence of either 3.3 or 16.6 mM glucose. These results show that beta-N-acetylglucosaminidase activity, a lysosomal hydrolase of pancreatic rat islets,--and only this enzyme--is modulated by glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗
PubMedDate not supplied

Prevalence of dermographism in children.

The prevalence of dermographism in our pediatric population was studied in 238 children of both sexes (128 boys and 110 girls) aged 2-14 years, randomly selected from a health care center. Skin reaction was evaluated after 5 min pressure (3,200 g/cm2) applied with a dermatographometer on a 5-cm length of dorsal skin. The reaction was considered positive when a wheal of more than 2 mm was observed. The prevalence of dermographism was found to be 24%, with a significant female predominance (33%) over males (16%). Forty-one percent of the children with dermographism reported exanthema in response to friction and pressure, which was compatible with symptomatic dermographism, compared with only 5% of those who yielded negative reactions. In order to assess the prevalence of dermographism in the atopic population, 100 patients in the 4-14 age range with respiratory disease (perennial allergic rhinitis and/or bronchial asthma) involving sensitization to aeroallergens (house dust mites and/or Alternaria) were studied. A positive response to the application of pressure (3,200 g/cm2) was observed in 47% of cases, this figure being significantly higher than in the general pediatric population.

Adolescent↗
PubMedDate not supplied

Icodextrin effluent leads to a greater proliferation than glucose effluent of human mesothelial cells studied ex vivo.

OBJECTIVE: To compare the effect of glucose (Glu) and icodextrin (Ico) dialysate on in vitro culture of mesothelial cells (MC) from peritoneal dialysis (PD) patients. DESIGN: Prospective, controlled comparative study on the effects of two PD solutions. SETTING: A tertiary-care public university hospital. PATIENTS: Sixteen PD patients regularly using Glu dialysate were asked to collect an 8-hour dwell peritoneal effluent on 2 different days, with an interval shorter than 7 days. In the first collection, 2.27% Glu solution and in the last, 7.5% Ico solution was infused. Human MC were isolated from the nocturnal peritoneal effluent bags and grown ex vivo. MAIN OUTCOME MEASURES: Mesothelial cell proliferative capacity ex vivo. RESULTS: Mesothelial cells were present in all patient dialysates except that of a single patient's Glu dialysate. The number of MC drained was similar with both solutions. After the initial culture reached confluence, MC were identified in 14 and 12 patients receiving Ico and Glu, respectively. However, in 1 patient using Ico and in 2 using Glu, the MC count at this stage was so low that further subculture could not be performed. Cells from Ico-derived solutions exhibited a higher degree of proliferation than cells from Glu-derived solutions. The morphology of MC was also different. Cells from drained effluent were typical in 11 patients using Glu solution in contrast with 14 patients using Ico. At confluence, the percentages of typical appearance were 50% and 92.9% (p < 0.05) in Glu and Ico respectively. CONCLUSIONS: Mesothelial cells taken from icodextrin effluent show a greater proliferation ex vivo than those taken from glucose effluent.

Cell Division↗