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Biomedical subjects

G Medrano

Publications and source records attributed to G Medrano.

At least 19 recordsLinked to original sources
PubMed1991

Giant T waves simulating apical hypertrophic myocardiopathy that disappear with sodium nitroprusside administration. Case report of pheochromocytoma.

Giant inverted T waves (amplitude greater than 1 mV) in precordial leads have been described in various disease processes. However, the pathophysiology of these anomalies has not been studied in depth. This paper analyzes repolarization abnormalities occurring in a case of pheochromocytoma in which giant T waves were unaffected by alpha-adrenergic blockade but were affected by administration of sodium nitroprusside. It is postulated that the probable cause of this aberration is myocardial ischemia of noncoronary origin resulting from an imbalance of supply and demand of oxygen that is relieved by the hemodynamic action of nitroprusside when left ventricular wall stress is reduced.

Adrenal Gland Neoplasms↗
PubMed1991

[The control of respiration in pulmonary fibrosis. The effect of O2 and CO2].

We have studied the mode of ventilation and chemosentivity in 10 patients suffering from pulmonary fibrosis. The total lung capacity was on average 63.5 +/- 8% of the predicted. Their static compliance was 0.078 +/- 0.05 l.cm of water. The patients were studied in the prone position breathing ambient air then on hyperoxia. The response to CO2 was assessed according to the rebreathing method of Read. The results of these patients were compared with those of 11 normal subjects. The ventilation at rest was normal, with a shortened respiratory time and a Ti/Ttot ratio which was lowered. The occlusion pressure (P0.1) was very much higher than that in normal subjects. This rise was correlated with an increase in pulmonary elastance and a reduction in vital capacity. The correction of hypoxia was without effect on the respiratory parameters. In relation to normal subjects the ventilatory response to carbon dioxide in fibrotics was decreased whilst the response of the P0.1 was increased expressing central hyperactivity. In conclusion, fibrotic patients have normal ventilation in spite of an increase in inspiratory work. This normal ventilation results from hyperactivity of the respiratory centre, as in the hyperventilation induced by carbon dioxide when at rest.

Adult↗
PubMed1988

Metabolic enzymatic activities in the intercostal and serratus muscles and in the latissimus dorsi of middle-aged normal men and patients with moderate obstructive pulmonary disease.

The glycolytic and oxidative enzyme activities (lactate dehydrogenase (LDH), hexokinase (HK), citrate synthase (CS) and 3-hydroxyacyl-CoA-dehydrogenase (HAD] were measured in the fifth internal and external intercostal muscles, in the vertical and horizontal parts of the serratus, an accessory inspiratory muscle, and in a non-respiratory muscle, the latissimus dorsi (LD) of twenty middle-aged men: nine subjects with normal lung function and eleven patients with moderate chronic obstructive pulmonary disease (COPD). In the normal subjects the enzyme activities of the respiratory muscles were similar to those of the LD, and there were no differences between the internal and the external intercostal muscles. In the COPD patients the metabolic activities of HK, CS and HAD were higher in both intercostals than in LD. Furthermore, there was a significant increase in these enzymatic activities as compared to the intercostals of the normal subjects. These data support the hypothesis that the internal and external intercostal muscles play a more important role in COPD patients than in normal subjects. They are consistent with the hypothesis that COPD has an endurance training effect on both intercostal muscles which could compensate for diaphragmatic disuse.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1984

Effects and mechanism of action of terbutaline on diaphragmatic contractility and fatigue.

We studied the effects of intravenously administered terbutaline on diaphragmatic force and fatigue during electrical stimulation of the diaphragm in 17 anesthetized dogs. The diaphragm was stimulated indirectly through the phrenic nerves with electrodes placed around the fifth roots and directly with electrodes surgically implanted in the abdominal side of each hemidiaphragm. Transdiaphragmatic pressure (Pdi) during direct or indirect supramaximal 2-s stimulation applied over a frequency range of 10-100 Hz was measured with balloon catheters during tracheal occlusion at functional residual capacity. In seven dogs the administration of terbutaline (0.5 mg) had no effect on Pdi at any stimulation frequency applied directly or indirectly. The effect of terbutaline (0.5 mg) on diaphragmatic fatigue was then tested in 10 other dogs. Diaphragmatic fatigue was produced by continuous 20-Hz electrical supramaxial stimulation of the phrenic nerves during 30 min. At the end of the fatigue procedure Pdi decreased by 50 +/- 5 and 30 +/- 8% of control values at 10 and 100 Hz, respectively, for either direct or indirect stimulation. The decrease in Pdi for low frequencies of stimulation (10 and 20 Hz) lasted 100 +/- 18 min, whereas it lasted only 40 +/- 10 min for the high frequencies (50 and 100 Hz). When terbutaline (0.5 mg) was administered after the fatiguing procedure, Pdi increased within 15 min by 20 +/- 4% at 10 Hz and by 12 +/- 3% at 100 Hz for either direct or indirect stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

[Spirometric modifications induced by bronchography. Effects of Salbutamol].

Bronchography enables an appreciation of the morphology and dynamics of the bronchi inaccessible to the fibroscope. However, this examination may aggravate pulmonary function in patients with chronic airflow obstruction. We have studied the effects of bronchography on forced expiration in order to identify and quantify possible spirometric changes. Thus spirometric tests were done at different times during the examination (V.C., F.E.V., flow-volume curves): before and after anaesthetizing the upper airways with xylocaine, after the introduction of contrast to the bronchi and finally after a Salbutamol aerosol. Spirometric values were unaffected by anaesthesia of the upper airways. On the other hand, the introduction of contrast led to a clear and constant fall in maximum expiratory flow, associated with a fall in forced vital capacity. These changes could not be reversed either after inhalation of Salbutamol or sub-cutaneous Terbutaline. The mechanisms producing the spirometric changes which we report does not seem to involve either the adrenergic system or the irritant receptors. Bronchial obstruction produced by the contrast does not alone appear to explain the changes induced by bronchography. Other mechanisms, not yet identified, probably contribute to the decrease in maximum expiratory flow.

Adult↗
PubMed1983

A comparative study on the effects of pindolol and propranolol on systemic and cardiac haemodynamics in hypertensive patients.

Eight out-patients with essential hypertension participated in a comparative, placebo-controlled study with a cross-over design. Pindolol and propranolol were administered orally in doses of 20.0 +/- 3.13 mg/d (mean +/- SEM) and 125.0 +/- 19.17 mg/d respectively. Pindolol reduced mean blood pressure by 11.9 mmHg; pre-ejection period index by 8.1 msec; total peripheral resistance by 3.1 mmHg min/L; and limb vascular resistance by 3.28 mmHg min 100 g/ml. Heart rate, cardiac output, plasma renin activity and urinary norepinephrine excretion rate were not altered by pindolol. Propranolol reduced mean blood pressure by 14.0 mmHg; heart rate by 9.1 beats/min; cardiac output by 0.57 L/min; limb blood flow by 1.06 ml/100 g.min; and plasma renin activity by 1.44 ng/ml/h; and increased pre-ejection period index by 8.7 msec. Total peripheral resistance, limb vascular resistance and urinary norepinephrine excretion rate were not altered by propranolol. It was concluded that: (1) the drugs, pindolol and propranolol, are equally effective as antihypertensive agents; (2) heart function and plasma renin activity are decreased by propranolol and unaltered by pindolol; (3) total peripheral resistance is decreased by pindolol and unaltered by propranolol; and (4) these findings may be explained by the intrinsic sympathomimetic activity exhibited by pindolol only.

Adult↗
PubMedDate not supplied

[Auricular Q wave in right precordial derivations. New sign of left auricular growth].

The authors present four cases of rheumatic heart disease with severe dilatation of the left atrium which reached the right profile in the radiologic study. An initial negative deflexion of the P-wave (qP) in the right precordial leads was recorder in these cases. The presence of qP was interpreted in view of the atrial activation and the solid angle of the right precordial leads as a variation of potential of the right atrial ceiling and/or of the high interatrial septum, a consequence of the dislocation of the right atrium produced by severe dilatation of the left atrium, demonstrated radiologically in the cases studied. Thee presence of qP is another undoubtably valuable sign for inferring a severe displacement of the left atrium toward the right profile.

Adolescent↗
PubMedDate not supplied

[Corrected transposition of the great arteries without associated abnormalities].

We studied 5 cases of corrected tansposition of big arteries without associated defects. Four of them showed situs solitus with apex to the left, and the fifth one showed dextroversion. In four of the cases the second sound was the only one, strong and to the left of the precordium; in four we found mild sistolic murmur in the third left intercostal space. In all of them, XR plates showed the largest liver lobe to the left, apex to the left in four and to the right in one, being possible to see the ascending aorta to the left in four cases. A patient with complete auriculoventricular block showed cardiomegaly and excavated middle arch. Three of them presented sinusal rithm, one had auriculoventricular block of variable degree and the last had complete auriculoventricular block. In four cases the AQRS showed a deviation to the left, and the other one to the right. In the foreground of the first septal vector was going from right to left. The analysis of the unipolar and thoracic morphologies had alterations in the intraventricular conduction which suggested a right branch block in derivations exploring the ventricle located to the left and potential QS in the right pre-cordials. We found a pattern of sistolic overload of the sistemic ventricle. Through determination made by the His Ecg we found that the alterations in conduction were distal. The electro-mechanic latent period of the ventricle located to the right was shorter than the opposite. The angiographic studio helped to establish the auriculoventricular discordant relations and to identify the ventricles position through their angiographic morphology. In the cases showing point to the left, the ventricle anatomically considered as the left one showed a triangular form and smooth walls, while the ventricle anatomically consider being the right one presented trabeculated walls. In dextroversion the anatomically left ventricle was egg-shaped with smooth walls. All of them presented the aorta above the pulmonar artery.

Adolescent↗
PubMedDate not supplied

[Vectorcardiographic findings in atrial enlargement].

Rational interpretation of changes of the P loop, due to atrial enlargements, must be based on the magnitude and spatial orientation of the main resulting vectors of the atrial activation phenomenon. Under normal conditions, these ones give origin to a mean vector oriented to the left, downward and slightly forward. Right atrial enlargement can be recognized by P loops of more than 100 mcv. The main axis of the elongated PF is comprised between + 60 degrees and + 90 degrees; that of the open PH between + 70 degrees and + 80 degrees and that of PS is located around + 135 degrees. Left atrial enlargement can be diagnosed by a characteristic box glove configuration of the PF loop as well as by an eight-shaped PH. In some cases, the PS loop also becomes eight-shaped. Biatrial enlargement gives rise to slurrings and notchings of the distal portion of the PF loop, a diphasic aspect and frequently an eight-shaped configuration of the PH loop and a triangular morphology of PS, whose base lasts 30 msec. or more.

Cardiomegaly↗
PubMedDate not supplied

[Liver cirrhosis: pulmonary function].

We performed a functional respiratory examination which consisted of arterial gasometry, spirometry, diffusion capacity to CO2, alveolo-arterial gradient of O2 and pulmonary volumes to 8 patients with cirrhosis diagnosed by clinical history, laboratory exams, abdominal ultrasound and histology. Our results showed a slight obstructive pattern of peripheric airways (FMM: 88.87 +/- 8.7%) in the spirometry, no difference in arterial gases at upright and recumbent position was observed, with low values of apO2 (75.51 +/- 1.16 upright and 75.87 +/- 2.16 mmHg recumbent) without statistic significance. The gradient G(Aa) O2 increased to (30.89 +/- 1.06 mmHg). Besides there was a diffusion abnormality with a DLCO2/VA of (71.87 +/- 6.05%). Breathing 100% O2, did not change the gradient which allows us to postulate the existence of an abnormality of gaseous interchange due to shunts. We found no relationship between albumin levels and DLCO2/VO neither with pO2 in upright position; there was a relationship at recumbent position between the hepatic disorder and the arterial desaturation. We concluded that there is no significant hypoxia even with position changes, there is increase of G (Aa) O2 by shunt type disorders and that this is probably related with albumin levels.

Adult↗
PubMedDate not supplied

[Response of normal children to the treadmill exercise test using the Bruce protocol].

Fifty nine boys and 41 girls underwent exercise stress testing (ETT), utilizing the Bruce protocol. Their mean age was 10 years. They were grouped by sex, age and body surface area. Blood pressure (BP), heart rate (HR) at rest, during exercise and after were monitored as well as the duration of the test and the energy cost. The HR and-BP had a similar linear relationship in both groups during the different stages of the test. The duration of the test expressed in minutes was 11.8 +/- 1.2 in boys and 10.7 +/- 1.2 in girls (P = 0.001). The oxygen consumption (ML/kg/min) was 45.2 +/- 4.9 and 41.9 +/- 4.5 that is equivalent to 12.9 +/- 1.4 and 11.9 +/- 1.2 mets for each group respectively. The group of boys of 6 (9.8) and 14 years of age (13.6) (P = 0.002) and in the girls in the 7 (9.5) and 10 years age group (11.8) P = 0.05. We conclude that 1) The ETT can be done in children safely but was have to take in consideration their age, sex, and body surface area in evaluating the results. 2) This study gives a reference to evaluate children with an without heart disease.

Adolescent↗
PubMedDate not supplied

Muscle fibre types in costal and crural diaphragm in normal men and in patients with moderate chronic respiratory disease.

Histochemical muscle fibre composition of human costal and crural diaphragm was determined in biopsies sampled during surgical procedures. Two groups were studied: 10 subjects with normal lung function and 8 patients with chronic obstructive respiratory disease. Muscle fibres were classified as type I (slow twitch) or type II (fast twitch) on the basis of their myofibrillar ATPase pH lability. There was no significant difference in fibre proportions between costal diaphragm (COD) and crural diaphragm (CRD) for both groups of subjects. Yet, in the normal group, the diameters of both types of fibres were larger in COD than in CRD. The diameters of both types of fibres of the obstructive patients were significantly decreased in COD as compared to the normals. Moreover, linear correlations between type I and II fibre diameters and VC, FEV1, FEV1/VC, and body weight were found in COD and not in CRD. The differences found in muscle fibre size support the idea that the mechanical respiratory load is different for COD and CRD, COD being the more important force generator. Chronic obstructive respiratory disease causes a significant decrease in COD fibre size but does not affect CRD.

Adult↗
PubMedDate not supplied

[Experimental reevaluation of myocardial ondulations in the early histological diagnosis of myocardial infarct].

This investigation was undertaken in order to experimentally reassess the value of myocardial waviness and stretching as early histological indicators of acute myocardial infarction. Twenty three dogs were subjected to periods of ischemia, from 30 minutes to 4 hours; wavy fibers were present in 87% and 91% of the ischemic and non-ischemic samples respectively. It is concluded that myocardial fiber waviness lacks significance as an indicator or early myocardial infarction, whose diagnosis remains a major challenge.

Animals↗