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Biomedical subjects

R Barrios

Publications and source records attributed to R Barrios.

At least 19 recordsLinked to original sources
PubMed1992

Effect of hydralazine on vascular mechanics in a canine lobar preparation of pulmonary embolism.

We studied the effect of hydralazine (H) on pulmonary vascular mechanics in an isolated, in situ, canine lobe model of normal and increased pulmonary vascular resistance (Rp) produced by Gelfoam embolization (GE). Pulmonary pressure-flow (P-Q) curves from 24 lobes were obtained at baseline and after each intervention. Hemodynamic parameters for analysis included: the mean critical closing pressure (Ppai), vascular conductance (1/Rp), lobar flow (QL), and the pulmonary inflow pressure (Ppa) at different levels (50, 100, 200, 400, and 600 ml/min) of a fixed flow. After the preparation was stabilized, the 24 lobes were classified into 2 groups. For group 1 (n = 8) we studied the effect of H on the normal pulmonary vasculature. In group 2 (n = 16) we studied the effect of GE. Following GE, this group was further divided in half. For group 2A (n = 8) we followed the natural history of GE with measurements at 15 and 60 min. For group 2B (n = 8) measurements were done 15 min after GE and repeated again 15 min after the infusion of H. For group 1 lobes, H promoted a significant decrease (p less than 0.001) in Ppa at fixed flows of 200, 400, and 600 ml/min compared to baseline, with no change in Ppa for flows below 100 ml/min. QL and 1/Rp increased (p less than 0.01), and there was not any significant change in Ppai. In group 2A lobes, GE produced an increase in Ppa at all levels of flow (p less than 0.01), QL and 1/Rp decreased (p less than 0.05), and there was an increase in Ppai (p less than 0.05). These changes remained stable over the 60 min of observation. For group 2B lobes, GE produced the same hemodynamic changes as in group 2A, and the infusion of H caused a decrease in Ppa at flows between 100 and 300 ml/min. (p less than 0.01) with no change in Ppa at flows below 100 ml/min. QL and 1/Rp increased (p less than 0.01) and Ppai did not change compared to 15 min after GE. We conclude that in the normal canine pulmonary vasculature as well as in the model of GE, H decreased Rp and did not affect mean critical closing pressure, all of which may be explained by an increase in vascular conductance due to an increase in vascular distensibility.

Animals↗
PubMed1991

Entamoeba histolytica: microtubule movement during mitosis.

The movement of microtubules (MTs) during nuclear division of Entamoeba histolytica was ultrastructurally studied. Regarding this MT movement, five stages of mitosis could be defined: prophase, metaphase, anaphase A, anaphase B, and telophase. In early stages of mitosis, chromatinic material appeared condensed, and MTs were detected in the center of the nucleus. Later, MTs seemed to grow from an electron-dense body located in the center of the nucleus. This body might be the microtubule organizing center, which organized the MTs, first in a lateral way, and later to form the mitotic spindle, which was made of a bundle of MTs joined by their ends. This junction of MTs to themselves could also be observed in cross-sections. The last stage of mitosis was the nuclear separation. Two different morphological types of intranuclear vesicles were also observed, which seemed to have different types of membrane. Both intranuclear vesicles were present during nuclear division, generally in clusters, and located close to the nuclear periphery.

Anaphase↗
PubMed1989

Experimental pulmonary fibrosis induced by paraquat plus oxygen in rats: a morphologic and biochemical sequential study.

Changes in lung structure and collagen metabolism were studied at 1, 2, 3, 4, 6, and 8 weeks in a model of pulmonary fibrosis induced in rats with paraquat plus hyperoxia. Morphologic examination of the lungs revealed that the earliest lesions consisted of severe and irreversible endothelial and alveolar epithelial cell damage. Afterward, an inflammatory process took place, initially dominated by polymorphonuclear leukocytes and then by mononuclear cells, but with the constant presence of granulocytes. From the fourth week on there were fibroblast proliferation and a moderate increase of mast cells. In the early stages alveolitis was focal, but from the second week the lungs were diffusely affected with severe distortion of the architecture. Collagen content was moderately increased in the first 2 weeks and then showed a progressive increment until the end of the experiment. Collagen synthesis was significantly elevated from the fourth week, coinciding with interstitial fibroblast proliferation, although there were some animals that showed increased collagen production from the first week. Collagenolytic activity occurred in 3 stages: at 2 weeks there was increased collagen degradation, at 3, 4, and 6 weeks the values showed a trimodal behavior, and at 8 weeks almost all experimental rats presented an important decrease of collagenolysis. Thus, the development of lung fibrosis was associated first with increased rates of collagen synthesis and later with a decrease of collagen degradation.

Animals↗
PubMed1989

[Guidelines for a fluoride prevention program].

The present work proposes the creation of a program for the prevention of caries and periodontal disease in schoolchildren, to be undertaken under the supervision of an odontologist; proper training of personnel to aid in this task is also proposed. Finally, it provides tabulated guidelines for the development of this program.

Adolescent↗
PubMed1988

Prevalence and severity of coronary atherosclerosis in males living in Mexico City: the Mexico City project.

The current prevalence of coronary atherosclerosis was investigated in 174 necropsic studies performed on males who died violently between 1984 and 1986 in Mexico City. In young adults, coronary atherosclerosis was found in 35% of the cases, 5% of whom had significant obstruction in one coronary vessel. In subjects aged 50-69 years, coronary atherosclerosis occurred in 69% of the cases and obstructive disease in 24%. Current figures suggest an increase in the severity of coronary atherosclerosis in this population which may be linked with nutritional changes. This makes further investigations, as well as the design of a program for ischemic heart disease prevention in Mexico City imperative.

Adult↗
PubMed1987

Subpopulations of T cells in lung biopsies from patients with pigeon breeder's disease.

Monoclonal antibodies were used to determine surface phenotypes of T cells in tissue obtained by open lung biopsies from patients with chronic hypersensitivity pneumonitis (pigeon breeder's disease). The results indicate that an increased number of suppressor/cytotoxic cells is present in these patients when compared with the number of helper/inducer cells. These findings, which were present within the interstitium, are consistent with those found in bronchoalveolar lavage of patients with this disease. In addition, in two-thirds of the patients there was a greater total number of helper and suppressor cells than the total count for Pan T cells. A possible interpretation of these findings might be the presence of both markers in the same cell.

Adult↗
PubMed1985

Hemodynamic effect of hydralazine in interstitial lung disease patients with cor pulmonale. Immediate and short-term evaluation at rest and during exercise.

Hydralazine was administered short-term to 13 patients who had stable interstitial lung disease (ILD), pulmonary arterial hypertension (PAH); mean pulmonary arterial pressure ( [PAP]=26 +/- 9 mm Hg), and cor pulmonale (CP). All patients were studied at rest and during exercise. After intravenous hydralazine at rest, there were statistically significant increases in cardiac index (CI) (p less than 0.001), arterial oxygen saturation (SaO2) (p less than 0.01), and mixed venous saturation (S-vO2) (p less than 0.01). Pulmonary vascular resistance (Rp) (p less than 0.005) and systemic resistance (Rs) decreased (p less than 0.001), and PAP did not change. During exercise, PAP did not change; however, CI (p less than 0.01), PaO2 (p less than 0.001), and S-vO2 (p less than 0.01) increased further. The increase in Rp was significantly reduced (p less than 0.01). After continuation of oral hydralazine therapy in 12 patients for 7 days, PAP at rest was not statistically different from control; Rp and Rs remained decreased (p less than 0.001). The same results were found for CI, PaO2, S-vO2, and Rs during exercise. Although PAP did not change from control values, the drug significantly reduced the increase in Rp (p less than 0.005). Vasodilator therapy with hydralazine could be useful in patients with stable ILD who have inflammation with minimal to moderate fibrosis and PAH and might be used as an adjunct to conventional therapy for ILD and CP.

Administration, Oral↗
PubMed1977

Intercellular junctions in "shock lung". A freeze-fracture study.

Intercellular junctions in the alveolar epithelium and in the capillary endothelium in lung from five dogs after hemorrhagic shock (mean blood pressure, 40 mm. Hg for 3 hours) and from five control dogs were observed in the electron microscope using the freeze-fracture technique. Following shock zonulae occludentes (tight junctions) in the alveolar epithelium showed alterations in substructure that were not present in control animals. These changes were morphologically similar to those reported in junctions altered after exposure to osmotic gradients with marked degradation and disappearance of junctional strands. The appearance of tight junctions in the capillary endothelium, which were of a rather poorly organized "leaky" type in control animals, was generally unaltered after shock. Disintegration and disappearance of junctional strands in "focal" regions, however, were occasionally observed. The increased pulmonary capillary permeability observed physiologically after hemorrhagic shock could be explained by such alterations of endothelial zonulae occludentes.

Animals↗
PubMedDate not supplied

[Colonic polyps: an analysis of the endoscopic and histopathological aspects].

The present study is a retrospective analysis of the endoscopic and histologic features of 728 polyps resected from 422 patients during the years 1980 to 1991. Mean age of the patients was 52 years (5 to 87), 63% male and 37% female. The histology of the lesions showed: adenoma: 60.3%, hyperplastic: 31.7; juvenile: 2.3% and miscellaneous: 5.7%. The 439 adenomas where found in 270 patients of which 151 (55.9%) were male and 119 (44.1%) female. The 231 hyperplastic polyps where found in 113 patients: 66 (58.4) male and 47 (41.6) female. All the hyperplastic polyps where less than 20 mm in diameter. Of the adenomas, 385 (87.7%) where less than 20 mm in diameter and had macroscopic appearance similar to the hyperplastic polyps. Of the 439 adenomas, 218 (49.6) where pediculated and 221 (50.4%) sessile. Of the hyperplastic polyps 53 (22.9%) where pediculated and 178 (77%) sessile. Of the adenomas, 351 (80%) where tubular and 88 (22%) had a villous component, most of the tubular adenomas where less than 15 mm in diameter and the villous component was more frequent as the polyps increased in size. Of the adenomas, 139 (30%) had dysplasia and of these 10% had cancer which represents a total of 3% of all the adenomas in this series. The grade of dysplasia was more severe as the adenomas was larger in size or had villous component. The polyps were located: 69.6 in the distal colon at the reach of the flexible sigmoidoscope and 30.4% in the proximal colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Analysis of rheumatic valvulopathy with scanning electron microscopy].

There is a high incidence of rheumatic endocarditis in our environment. Therefore it is important to know the structural characteristics of the valvular lesions in order to better understand the physiopathologic pathways of tissue injury. We have chosen a non-conventional method, the scanning electron microscopy. There were very few such reports in the current literature. We analyzed ten mitral valve with rheumatic scarring lesion and five normal, as a control group. We were able to establish three structural patterns. 1) Stone pavement like (endocardium with nuclear bulge cells and marginal folds at the cell boundaries, abundant number of microvillous projections and few areas of endothelial loosening). 2) Cerebroid (subendothelium with wrinkles caused by deformity of the valve with or without endothelial loosening) and 3) Smooth pattern (flattened endothelium with scanty microvillous projections and abundant areas of endothelial denundation and exposition of subendothelium). More damage was noted in the auricular surface of the rheumatic group, characterized by a predominance of the smooth pattern. We found Lambl's excrecences in two mitral leaflets, they were formed by collagen break fascicles of the subendothelium. This technique allowed us to analyze integrity of the endocardial selective barrier and the interactions between the damaged surface of the valve and elements of the peripheral blood and showed more endocardial injury in the rheumatic group. These alterations could play an important role in the pathogenesis of this disease.

Adult↗
PubMedDate not supplied

[Multi-technical management of biliary fistula].

Biliary fistula is an occasional complication of cholecystectomy and are usually associated to retained biliary stones, surgical trauma of the biliary ducts and local infection. They were mainly treated by surgical methods up to the acquisition of the new endoscopic and percutaneous techniques used together with parenteral and enteral nutrition and new antibiotics. A total of seven patients with diagnosis of biliary fistula were seen between 1984 and 1990 at the "Unidad de Gastroenterología y Cirugía Digestiva" of the Clínica Sanatrix en Caracas. Average age was 50 with ranged between 31 and 76, 4 were male and 3 female. The fistulas were in 1 due to necrotizing pancreatitis, in 3 to lost of the ligation of the cystic duct, 2 were due to accidental injury of the common duct and the last case was a partial dehiscence of a choledoco-jejunostomy after the resection of a common duct cyst. Four of the cases were choledoco-cutaneous fistula, one hepatocutaneous, two hepatoduodenal. All the seven patients had subhepatic collections, one had a retroperitoneal collection, two had subdiaphragmatic collections and one had multiple hepatic abscesses. The abdominal collections were treated by percutaneous drainage using mainly the Ring-McLean and Van Sonnenberg tubes. The fistula was occluded with biliary prosthesis in four cases, using either endoscopic, percutaneous or mixed technique to place the stent. Patency of the stents ranged between 2 weeks and 24 months. Control time was from 2 to 40 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Mast cells and idiopathic lung fibrosis.

Mast cells are usually related with allergic reactions in the lung. This cells has a biochemical repertoire capable of modulate inflammatory reactions in this organ. The relation of this cell with idiopathic pulmonary fibrosis (IPF), has not been studied in depth. There is no agreement in which is the best technique for counting mast cells and what are the normal counts of these cells in the lung. We analyse some of the reported "normal values" and the differences within IPF and patients with nonfibrotic lung diseases. The results of the present study demonstrate that the largest population of mast cells in IPF patients were the interstitium (342 +/- 83 cells) compared with the nonfibrotic patients (31 +/- 8 cells), and almost equal in both groups of patients in the subpleural, peribronchiolar and perivascular areas. However, it is necessary to unify criteria, in order to define what the normal values for mast cells in the lung are.

Adolescent↗
PubMedDate not supplied

[The effect of gelfoam embolism in vascular conduction and critical pressure in the isolated canine lobe].

Pulmonary pressure-flow curves, hemodynamic and blood gas parameters in West's zone II condition were obtained in nine isolated in situ left lower lobes (LLL) before (condition A), and after 15, 30 and 60 minutes of lobar gelfoam embolization (GE) (condition B) in order to know the natural history of this model. After GE a decrease in PaO2 and lobar O2 were noticed (p less than 0.05). Vascular conductance (p less than 0.001) and lobar blood flow decreased (p less than 0.05), accompanied by a significant increase in the inflow (p less than 0.01) and in the mean closing pressures (p less than 0.01). These parameters did not change during the time of observation at condition B. Nor the cardiac output or the minimal closing pressure changed in relation to condition A. LLL angiographic findings showed evidence of arterial occlusion and the pattern of obstruction was not homogeneous. Lobes histology showed occluded arteries of more than 300 micrometers of diameter. We concluded that in this canine model of increased pulmonary vascular resistance, pulmonary vascular conductance and mean closing pressure change, remain stable during 60 minutes after GE allowing us to know the natural history of the preparation. Condition than allow to perform and evaluate other interventions on lung vascular mechanics in the experimental setting of pulmonary embolization.

Animals↗
PubMedDate not supplied

[Routine preoperative cholangiopancreatography?].

Since the early 50s, the routine use of operative cholangiography in biliary surgery has decreased the rate of negative choledochotomy and retained stones. In the last twenty years no further progress has occurred and negative choledochotomy rate remains at 30% and for retained stones at 1.3%. Modern endoscopic technology has improved the diagnosis and treatment of biliary diseases so we think that the routine use of endoscopic retrograde cholangiopancreatography (ERCP) as a preoperative study for patients to be surgically treated of biliary disease can reduce the incidence of negative choledochotomies, retained stones and duodenostomies that are the most important sources of biliary surgery complications. The results of ERCP as routine preoperative study in patients with diagnosis of symptomatic gallstones selected for surgical treatment are discussed. From June 1988 to June 1989 56 patients who filled the requirements were included. Ultrasound scan, laboratory test. EKG and complete digestive studies were performed at admission. ERCP was done immediately before surgery. Abnormalities on biliary tract were seen in 10 cases (17.9%). Six (10.7%) had stones in the common duct, in 4 of these patients (7.1%) the lithiasis was unsuspected, Four cases (7.1%) had dilated ducts, three of them with narrowing of the distal end of the choledochus. In 5 cases with duct stones and 3 with dilated ducts an endoscopic sphincterotomy was performed at the same time of the study, stones were withdrawn and biliary system cleared before laparotomy. Only one choledochotomy was done in a patient with a carcinoma of the gallbladder and a big stone impacted in cystic duct that produced compression of the common bile duct (Mirizzi Syndrome).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Cardiovascular abnormalities in Ehlers-Danlos syndrome. Report of a case].

This is the case of a 34-year-old woman with Ehlers-Danlos syndrome whose cardiopulmonary manifestations are the following: Prolapse of mitral and tricuspid valves. Aneurysmal dilatation of main arteries without aortic or pulmonary insufficiency. Disturbances in pulmonary function tests and pulmonary arterial hypertension. The diagnosis was verified by skin biopsy and an electron microscopic study. Due to the clinical and histopathological characteristics, we have considered this case to be a non-specified type of the 10 varieties described up to now, and have decided to report it also because of the interesting findings in the hemodynamic and pulmonary function tests.

Adult↗
PubMedDate not supplied

[A change in glomerular permeability in renovascular hypertension. Participation of angiotensin and structural lesions].

To characterize the decrease in glomerular permeability that occurs in contralateral kidney of renovascular hypertension, glomerular hemodynamics were studied in Goldblatt hypertensive and normotensive control rats. The effects of converting enzyme inhibition (captopril) and renal vasodilatation induced with hyperoncotic plasma were evaluated: in addition, glomerular morphometry was performed. In hypertension, glomerular capillary pressure was increased, ultrafiltration coefficient was decreased, single-nephron filtration rate was normal and afferent resistance was elevated. Captopril rose glomerular filtration rate only in normotensive rats, but ultrafiltration coefficient increased in both groups. Hyperoncotic plasma induced a 98% increment in filtration rate and ultrafiltration coefficient rose by 48% in normotensive group. In hypertensive rats, filtration rate increased only 15% and ultrafiltration coefficient diminished 6%, morphometric studies showed dilatation of capillary loops and a larger glomerular volume. Similar response to captopril in both groups of rats suggest that the reduction in ultrafiltration coefficient in hypertension is not dependent of angiotensin; lack of response to hyperoncotic plasma suggests that it could be produced by structural changes in capillary wall that diminish hydraulic permeability since the larger glomerular volume indicates a greater area for filtration.

Angiotensin II↗