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Biomedical subjects

A Torres

Publications and source records attributed to A Torres.

At least 523 records · Page 29Linked to original sources
PubMed1992

[The morphological bases of the pathogenesis of the "stress ulcer": experimental vagotomy and adrenalectomy].

To study the pathogenic mechanisms of stress ulcers, we have studied the morphological changes (micro and macroscopic) occurring in the stomach and duodenum in Wistar rats submitted to a technique producing stress (space restriction and water immersion), as well as the changes produced by vagotomy and adrenalectomy done before stress. Severe vasoconstriction in the submucosa and other histologic signs (minimal stress signs) as well as the presence of intramucosal foci of necrosis and ulcerations (Maximal stress signs) allow us to attribute the origin of stress ulcers directly or indirectly, to ischemia. Previous truncal vagotomy prevents maximal lesions of stress but not the so-called minimal lesions, thus suggesting that the vagus nerve potentiates the lesions produced by ischemia. Adrenalectomy increases the presence and development of stress ulcers therefore suggesting that neither steroids nor catecholamines are involved in their pathogenic mechanism.

Adrenal Glands↗
PubMed1992

[The cardiology consultation in a health-service area hospital. The clinical aspects and the demand for diagnostic procedures].

Four consecutive years (1987-1990) outpatients attendance at a cardiology clinic was recorded in a district hospital with a catchment area of 200,000 inhabitants. The aim being to identify and evaluate the demand for cardiology consultations. A system for recording diagnoses was developed, based on the WONCA. The total number of consultations was 26,273, 27% being new patients, 78% of whom were referred by family doctors and health centers. Of the total, 57% were male. The most common age groups being from 60 to 69 (25%) and from 50 to 59 (23%); 22% were over 69. In 13.7% of the consultations, the find diagnosis was of "healthy hearts", in 16.7% valvular heart disease, in 31.5% ischaemic heart disease, in 15.1% arrhythmias, in 8.4% hypertension, and the remainder were other diseases. We carried out 4,406 echocardiograms, 1,408 exercise tests and 511 Holter monitoring traces. There were 322 direct hospital admissions, and 6,094 discharges in the four years period. We consider this type of records to be useful organizing cardiology outpatients clinics, analyzing the demand, and planning the use of health care resources, as well as estimating future needs and assessing quality of care.

Age Factors↗
PubMed1991

Evaluation of serum CA 125 as a tumor marker in non-small cell lung cancer.

Serum CA 125 levels were evaluated in 130 healthy subjects and 133 patients with untreated pulmonary lesions. These were 33 patients with benign pulmonary conditions and 100 with lung cancer. The mean concentration of CA 125 was higher in patients with lung cancer (37 +/- 81 U/ml) than in those with nonmalignant disease (4.2 +/- 5.7 U/ml) (P less than 0.01). In the healthy control group CA 125 concentrations were significantly lower (0.63 +/- 1.5 U/ml) (P less than 0.001). In patients with lung cancer the concentration of this tumor marker was related to the tumor-node-metastasis (TNM) stage. At a cut-off value of 15 U/ml, CA 125 had a sensitivity of 44%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 65% with respect to healthy subjects; in patients with benign pulmonary conditions, these values were 44%, 94%, 94%, and 31%, respectively. At this cut-off value, a correlation between the respectability prognosis and the likelihood of survival 24 months posttreatment was observed. These findings suggest that CA 125 can be used as an adjunctive test in the management of patients with lung cancer patients.

Aged↗
PubMed1991

Electrolyte transport in piglets infected with transmissible gastroenteritis virus. Stimulation by verapamil and clonidine.

The effects of clonidine, an alpha 2-adrenergic agonist, and verapamil, a Ca2+ channel blocker, on Na+ and Cl- absorption were studied in stripped jejunal mucosa from control and transmissible-gastroenteritis-virus-infected piglets. All infected piglets developed severe diarrhea 18-24 hours after oral inoculation. Jejunum from infected animals, as compared with control jejunum, had decreased mucosal-to-serosal, serosal-to-mucosal, and net Na+ and Cl- fluxes. Clonidine and verapamil caused a decrease in short-circuit current and stimulation of Na+ and Cl- absorption in control jejunum. In infected piglets, although the jejunum exhibited severe villus atrophy, both drugs stimulated Na+ and Cl- absorption and the magnitude of Na+ and Cl- absorption was similar in control and transmissible-gastroenteritis-infected jejunum. In contrast, D-glucose stimulated Na+ absorption, and the decrease in short-circuit current caused by verapamil and clonidine, were decreased in transmissible-gastroenteritis-infected jejunum. Such pharmacological stimulation of Na+ and Cl- absorption might be useful in the management and treatment of certain viral diarrheal diseases.

Animals↗
PubMed1991

Cardiac parasympathetic innervation in Chagas' heart disease.

Trypanosoma cruzi is thought to selectively destroy the postganglionic cardiac vagal neurons of chagasic cardiac patients. This theory is based on morphologic and functional evidences obtained from chagasic individuals who were in very advanced stages of the disease. We have studied chagasic patients who were in both the early and late stages of the disease. Our findings and the review of the available literature suggest that myocardial damage and mild left ventricular dilatation precede the cardiac parasympathetic abnormalities. Furthermore, we have found a strong correlation between the degree of left ventricular dilatation and the extent of cardiac parasympathetic impairment. Consequently, we propose that the cardiac parasympathetic abnormalities arise as a compensating mechanism for the progressive left ventricular dilatation.

Animals↗
PubMed1991

Life-threatening cervico-mediastinal haematoma after carotid sinus massage.

Retropharyngeal and cervico-mediastinal haematomas are rare but potentially fatal entities. The potential for airway compression necessitates rapid assessment and treatment. A cervico-mediastinal haematoma following carotid sinus massage which required cervical drainage is presented. This is a life-threatening event demanding a high index of suspicion. A review of the literature and indications for treatment are discussed.

Adult↗
PubMed1991

Calcitonin, an important factor in the calcemic response to parathyroid hormone in the rat.

The role of calcitonin on the calcemic response to parathyroid hormone (PTH) in renal failure has not been evaluated previously. Often animal studies evaluating the calcemic response to PTH in renal failure are performed in thyroparathyroidectomized (TPTX) animals, and thus eliminate any potential physiologic effect of calcitonin. In addition, parathyroidectomy (PTX), presumably by reduction of high PTH levels, has corrected the calcemic response to PTH in animals with renal failure. The present study was designed to evaluate the effect of endogenous calcitonin production on the calcemic response to PTH in rats with renal failure and secondary hyperparathyroidism, and in rats with normal renal function with diet induced hyperparathyroidism. Four groups of rats were evaluated: 1) chronic renal failure plus TPTX with autotransplant of the parathyroid gland, (CT-) CRF; 2) chronic renal failure plus selective PTX with autotransplant of the parathyroid gland, (CT+) CRF; 3) normal renal function plus TPTX with autotransplant of the parathyroid gland, (CT-) NRF; and 4) normal renal function plus selective PTX with autotransplant of the parathyroid gland, (CT+) NRF. Renal failure was surgically induced by a two-stage 5/6 nephrectomy, and exogenous thyroxine was administered to the two thyroidectomized (CT-) groups. Hyperparathyroidism was induced with a high phosphate diet (1.2%), and thus at the time of PTH infusion, PTH levels were (CT-) CRF 84 +/- 16, (CT+) CRF 89 +/- 21, (CT-) NRF 37 +/- 7, and (CT+) NRF 31 +/- 4 pg/ml, respectively (normal 21 +/- 3 pg/ml). Rat 1-34 PTH (2.6 U/hr) was infused for 48 hours via a subcutaneously implanted Alzet pump.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Sigmoidal relationship between calcitonin and calcium: studies in normal, parathyroidectomized, and azotemic rats.

Calcitonin secretion is stimulated by acute hypercalcemia. Furthermore, in the rat, the calcemic response to parathyroid hormone (PTH) is decreased by calcitonin stimulation. However, in renal failure, it is not known if an increase in the serum calcium concentration within the physiologic range of serum calcium stimulates calcitonin and whether the increased calcitonin decreases the calcemic response to PTH. In the present study, four groups of pair-fed rats were evaluated: normals (N); parathyroidectomy (PTX); and two groups with renal failure (RF)--basal serum calcium less than 8.5 mg/dl (RFa) and basal serum calcium greater than 8.5 mg/dl (RFb). Hypocalcemia was induced by parathyroidectomy or in the RFa group, by a high phosphate diet. Increases in the serum calcium were produced by a 48 hour infusion of rat 1-34 PTH. In the RFa and PTX groups, stimulation of calcitonin was observed as the serum calcium increased from hypocalcemia to normal levels of calcium (P less than 0.01). In all four groups, increasing the serum calcium from normal levels to hypercalcemia increased the serum calcitonin level (P less than 0.05). The relationship between serum calcitonin and calcium was best expressed as a sigmoidal curve. In the two groups with basal hypocalcemia, PTX and RFa, the calcitonin-calcium curve was shifted to the left of the N and RFb groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Calcemic response to parathyroid hormone in renal failure: role of phosphorus and its effect on calcitriol.

The calcemic response to parathyroid hormone (PTH) is decreased in renal failure. The reduction of hyperphosphatemia improves the calcemic response to PTH in animals with advanced renal failure. However, since low calcitriol levels in renal failure may also contribute to the decreased calcemic response to PTH, the improved calcemic response observed during the reduction of serum phosphorus may be partially mediated by an increase in serum calcitriol levels. The present study evaluated the calcemic response to PTH in rats with moderate and advanced renal failure and how this response was modified by a high and a low phosphorus diet. In addition, the effect of a change in dietary phosphorus on calcitriol levels was also evaluated. A 48-hour continuous infusion of 1-34 rat PTH increased the serum calcium level to 18.2 +/- 0.4 mg/dl in normal rats, versus 13.7 +/- 0.9 and 12.1 +/- 0.2 mg/dl in rats with moderate and advanced renal failure, respectively. During the PTH infusion, a high phosphorus diet increased the serum phosphorus and resulted in a reduced calcemic response to PTH at each level of renal function; respective serum calcium levels were 13.8 +/- 0.6 mg/dl in normals, 11.2 +/- 0.2 mg/dl in moderate renal failure and 9.6 +/- 0.5 mg/dl in advanced renal failure. In normal rats and in rats with moderate renal failure, dietary phosphorus restriction during the PTH infusion increased serum calcitriol levels. In rats with advanced renal failure, serum calcitriol levels were lower than in the other two groups and were not affected by changes in dietary phosphorus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Mechanisms of abnormal gas exchange in patients with pneumonia.

The mechanisms of abnormal gas exchange in patients with pneumonia and the gas exchange response while breathing high inspired O2 concentrations have not been clearly elucidated. To this end, we studied 23 inpatients with pneumonia and mild to severe arterial hypoxemia and/or increased alveolar - arterial O2 difference. Ventilation-perfusion (VA/Q) distributions were obtained upon breathing room air (or maintenance inspired oxygen fraction) and 100% O2 in random order. Subjects were divided in two groups according to whether they were spontaneously breathing (SB, n = 13) or their lungs were mechanically ventilated (MV) because of acute severe respiratory failure (n = 10). The SB patients showed only small amounts of shunt (7 +/- 2%) (mean +/- standard error) and moderate VA/Q mismatching, characterized by the presence of a small percentage of blood flow to low VA/Q units (VA/Q less than 0.1) (4 +/- 1%). In contrast, patients whose lungs were MV had larger shunts (22 +/- 5%) and greater percent of perfusion to low VA/Q units (11 +/- 5%). While breathing 100% O2, shunt remained unchanged but the dispersion of the pulmonary blood flow distribution (log SDQ) (normal range, 0.3-0.6) increased in each group (from 1.04 +/- 0.10 to 1.29 +/- 0.13 in SB and from 1.40 +/- 0.11 to 1.64 +/- 0.14 in MV; P less than 0.05 each), suggesting release of hypoxic pulmonary vasoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Statistical modeling of prognostic indices for evaluation of critically ill patients.

OBJECTIVE: To identify the most predictive association of variables from the usual indices of severity of illness by statistical objective analysis. DESIGN: Logistic regression analysis of the different variables of the most important indices. SETTING: A general critical care medicine group practice in a university hospital. PATIENTS: A total of 630 critical care patients age 12 to 87 yrs were evaluated. The most important indices of severity of illness and the corresponding variables were recorded and the patient's course was followed for 3 months after ICU admission. MEASUREMENTS AND MAIN RESULTS: One of our hypotheses was that the inclusion of an excessive number of variables to obtain the most common prognostic indices of mortality in critical care patients results in an underestimation of mortality and a redundancy of prognostic information. We performed a logistic regression analysis using the variables of the currently used indices of critical care prognosis: Acute Physiology Score, Simplified Acute Physiology Score, Acute Physiology Score-II, and Mortality Prediction Model. This mathematical approach resulted in a model of five variables: organ system failure, blood glucose, serum calcium, serum prothrombin activity, and serum osmolality. The score obtained from this model gave accurate prognostic criteria:sensitivity 91.2% and specificity 90%, using a cutoff point of 0.7; sensitivity 86% and, specificity 94%, using a cutoff point of 0.5. CONCLUSIONS: Our results show that suitable statistical management of the discriminant prognostic variables allows reduction of the number of variables of the severity indices currently used, obtaining five more predictive variables.

Adolescent↗
PubMed1991

Reduced environmental exposure to aerosolized ribavirin using a simple containment system.

To minimize the exposure of health care workers to aerosolized ribavirin, we designed a double tent containment system with circulating mist and suction applied between the tents and we evaluated the ability of this system to contain and evacuate aerosolized ribavirin. While the drug was administered with this system at three institutions, three air sampling pumps at different locations in the room and one worn by the investigator (personal breathing zone) collected air samples onto filters for assay of ambient ribavirin. Ribavirin determinations were made by high performance liquid chromatography. A 5- to greater than 20-fold decrease in ambient ribavirin concentrations was observed with the containment system compared with those detected with a single oxyhood in use. The personal breathing zone concentration was 566.0 micrograms/m3 with the oxyhood alone and fell to a mean concentration of 43.81 +/- 33.40 micrograms/m3 with the containment system. Though the risk to exposed health care workers is unknown, this system offers a simple way to decrease significantly occupational exposure to ribavirin.

Administration, Inhalation↗
PubMed1991

Severe community-acquired pneumonia. Epidemiology and prognostic factors.

Over a period of 4 consecutive yr, 92 nonimmunosuppressed patients (21 women and 71 men aged 53 +/- 16 yr, means = SD) with critical acute respiratory failure (PaO2/FiO2, 209 +/- 9 mm Hg) caused by severe community-acquired pneumonia were admitted to the respiratory intensive care unit (RICU) of a general hospital. The most frequent underlying clinical condition was chronic obstructive pulmonary disease (44 patients, 48%). A total of 56 patients (61%) required mechanical ventilation for a mean period of 10.7 +/- 12.5 days, 29 of them (52%) needing PEEP (9.9 +/- 3.8 cm H2O). A group of 23 (25%) patients had criteria of adult respiratory distress syndrome (ARDS). A causal microorganism was identified in 48 patients (52%), the two most frequent etiologies being Streptococcus pneumoniae (14, 15%) and Legionella pneumophila (13, 14%). Pseudomonas aeruginosa (5, 5%) was always associated with bronchiectasis. Mortality due to severe community-acquired pneumonia was 22% (20 patients). According to univariate analysis, mortality was associated with anticipated death within 4 to 5 yr, inadequate antibiotic treatment before RICU admission, mechanical ventilation requirements, use of PEEP, FIO2 greater than 0.6, coexistence of ARDS, radiographic spread of the pneumonia during RICU admission, septic shock, bacteremia, and P. aeruginosa as the cause of the pneumonia. Further, recursive partitioning analysis selected two factors significantly related to the prognosis: the radiographic spread of the pneumonia during RICU admission and the presence of septic shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗