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Biomedical subjects

A Munoz

Publications and source records attributed to A Munoz.

At least 55 records · Page 3Linked to original sources
PubMed1988

The relationship of blood lead to systolic blood pressure in a longitudinal study of policemen.

We examined the relationship of blood lead level to systolic and diastolic blood pressure in a longitudinal study of 89 Boston, MA, policemen. At the second examination blood lead level and blood pressure were measured in triplicate. Blood pressure measurements were taken in a similar fashion in years 3, 4, and 5. Multivariate analysis using a first-order autoregressive model revealed that after adjusting for previous systolic blood pressure, body mass index, age, and cigarette smoking, an elevated blood lead level was a significant predictor of subsequent systolic blood pressure. Bootstrap simulations of these models provided supporting evidence for the observed association. These data suggest that blood lead level can influence systolic blood pressure even within the normal range.

Adult↗
PubMed1988

Pattern of blood vessels in forelimbs of three strains of mice.

A technique was developed for visualizing the pattern of arteries in the adult mouse forelimb. The aorta was cannulated and injected with blue stained Batson's Number 17 Anatomic Compound to perfuse the forelimb arteries; the ossified skeleton was stained and the soft tissues were cleared, making it possible to examine the entire arterial system in the intact specimen. The pattern of distribution of arteries were compared in 120 forelimbs from three strains of mice, two inbred and one hybrid. Significant differences between the three strains were found for 9 of 16 variations evaluated. Differences in the point of origin of vessels were the most common; differences in the fusion of vessels, the extension of vessels and the presence of extra vessels were also identified. The patterns were much more constant in the two inbred strains than in the hybrid strain, suggesting the importance of genetic factors in determining the arterial pattern. Absence of major vessels and an abnormal persistence of embryonic vessels, which have been observed in association with skeletal malformations, were not observed in any of the 120 normal adult mouse forelimbs examined.

Animals↗
PubMed1987

Effect of linoleic and oleic acids on blood pressure, blood viscosity, and erythrocyte cation transport.

It has been proposed that dietary linoleic acid lowers blood pressure (BP) by being converted to arachidonic acid and prostanoids of the two-ene series. We tested the effects of linoleic acid on plasma arachidonic acid, blood pressure, blood viscosity, and RBC cation transport. Oleic acid, the major dietary monounsaturated fat and which is not a prostanoid precursor, was used as a control. Seventeen adults consumed 23 g/d of linoleic acid or oleic acid provided by genetic variants of safflower seed, each for 4 weeks in a double-blind crossover design. Linoleic and oleic acids were enriched significantly in the plasma cholesteryl esters, phospholipids and triglycerides during the respective periods of supplementation but there was no increase in arachidonate. Mean BP was 116.1/76.8 during ingestion of oleic and 113.6/74.6 during ingestion of linoleic acid (p = 0.09 systolic, p = 0.12 diastolic). The power of the study was over 75% for detecting a significant (p less than 0.05) effect of 4 mm Hg in systolic BP or diastolic BP. Whole blood and plasma viscosity, and RBC Li/Na countertransport, Na/K cotransport, and Na pump systems (Vmax) were unchanged during the protocol. Therefore, variations in dietary linoleic or oleic acids are unlikely to have major effects on BP or on several membrane-dependent erythrocyte functions related to hypertension.

Adult↗
PubMed1987

Electrophysiologic effects and pharmacokinetics of intravenous penticainide (CM 7857).

Penticainide is a new class I antiarrhythmic agent. Its electrophysiological effects and pharmacokinetic properties were studied in 28 patients undergoing endocavitary exploration for paroxysmal supraventricular tachycardia (10 cases), WPW syndrome involving an accessory pathway (5 cases), and unexplained dizziness (13 cases). Increasing doses of penticainide were infused in the first 18 patients (0.12 up to 3.5 mg kg-1). The next ten patients received 4 mg kg-1 over a 30 minute period. Penticainide shortened the sinus cycle length and increased the transnodal conduction time. The ventricular conduction time tended to increase. Atrial functional refractory period increased when atrioventricular nodal and ventricular refractory periods remained unchanged. In patients with previous supraventricular tachycardias all triggered arrhythmias were prevented with dosages higher than 2 mg kg-1 and related blood levels higher than 3 mg l-1. A dose-dependency of plasma and renal clearance was documented. Average Cmax values after 4 mg kg-1 was 7.37 +/- 1.28 mg l-1. No adverse events occurred during the trial and penticainide proved to be well tolerated.

Adult↗
PubMed1987

Partitioning of pulmonary resistance during constriction in the dog: effects of volume history.

We assessed the relative changes in airways and lung tissue with bronchoconstriction, and the changes in each during and following a deep inhalation (DI). We partitioned pulmonary resistance (RL) into airway (Raw) and tissue (Vtis) components using alveolar capsules in 10 anesthetized, paralyzed, and open-chested dogs ventilated sinusoidally with 350-ml breaths at 1 Hz. We made measurements before and during bronchoconstriction induced by vagal stimulation or inhalation of histamine or prostaglandin F2 alpha (PGF2 alpha), each of which decreased dynamic compliance by approximately 40%. With histamine and PGF2 alpha the rise in RL was predominantly due to Vtis. With vagal stimulation there was a relatively greater increase in Raw than Vtis. At higher lung volumes, Vtis increases offset falls in Raw, producing higher RL at these volumes before and during constriction with PGF2 alpha and histamine. During constriction with vagal stimulation, the fall in Raw with inflation overrode the rise in Vtis, resulting in a lower RL at the higher compared with the lower lung volume. The changes seen after a DI in the control and constricted states were due to alterations in tissue properties, both viscous and elastic. However, the relative hysteresis of the airways and parenchyma were equal, since Raw, our index of airway size, was unchanged after a DI.

Airway Resistance↗
PubMed1987

The effect of maternal cigarette smoking on the pulmonary function of children and adolescents. Analyses of data from two populations.

To evaluate the role of the use of different analytical techniques in determining differences in the reported effects of passive smoking in children and adolescents, data sets from 2 studies that had previously reported divergent results were subjected to a uniform analytic procedure using a first-order autoregressive model (AR1). Although the populations studied differed in age distribution and the frequency of both personal and maternal smoking, the assumptions of the AR1 model were met by both data sets, and the models developed fit both data sets well. Coefficients for personal smoking from the study-specific models were almost identical. An effect of maternal smoking on FEV1, which has been reported for the East Boston data, again was observed, but no such effect was observed for the Tucson data set. These findings suggest that the differences in reported results are not related simply to model specificity and that real differences in exposure or response to exposure may be occurring in different climatic situations. Such differences need to be taken into account in any assessment of indoor exposure to potentially noxious agents.

Adolescent↗
PubMed1987

Assessment of genetic and nongenetic influences on pulmonary function. A twin study.

To better understand the extent to which familial similarities in pulmonary function (PF) are attributable to genetic rather than to shared environmental influences, we studied the twinship aggregation of PF in 256 monozygotic (MZ) and 158 dizygotic (DZ) adult twin members of the Greater Boston Twin Registry. Genetic influences on various spirometric measures were estimated with twinship intrapair correlations adjusted using a regression model to control for similarities in the anthropomorphic characteristics of twins, and for the effects of a number of environmental factors that included childhood respiratory illness, occupational dust exposure, and smoking history. A significant influence of smoking on all air-flow measures was observed in this population for whom genetic similarities were adjusted. However, highly significant adjusted intrapair correlations for all spirometric measures, ranging from 0.52 to 0.76, were observed for the MZ twins. The intrapair correlations for the DZ twins were approximately one-half the magnitude of those for the MZ twins. These data suggest that a large proportion of the measured variability in PF may be accounted for by genetic influences other than those associated with body size.

Adult↗
PubMed1987

Daily air pollution effects on children's respiratory symptoms and peak expiratory flow.

To identify acute respiratory health effects associated with air pollution due to coal combustion, a subgroup of elementary school-aged children was selected from a large cross-sectional study and followed daily for eight months. Children were selected to obtain three equal-sized groups: one without respiratory symptoms, one with symptoms of persistent wheeze, and one with cough or phlegm production but without persistent wheeze. Parents completed a daily diary of symptoms from which illness constellations of upper respiratory illness (URI) and lower respiratory illness (LRI) and the symptom of wheeze were derived. Peak expiratory flow rate (PEFR) was measured daily for nine consecutive weeks during the eight-month study period. Maximum hourly concentrations of sulfur dioxide, nitrogen dioxide, ozone, and coefficient of haze for each 24-hour period, as well as minimum hourly temperature, were correlated with daily URI, LRI, wheeze, and PEFR using multiple regression models adjusting for illness occurrence or level of PEFR on the immediately preceding day. Respiratory illness on the preceding day was the most important predictor of current illness. A drop in temperature was associated with increased URI and LRI but not with increased wheeze or with a decrease in level of PEFR. No air pollutant was strongly associated with respiratory illness or with level of PEFR, either in the group of children as a whole, or in either of the symptomatic subgroups; the pollutant concentrations observed, however, were uniformly lower than current ambient air quality standards. Moreover, since exposure estimation based on monitoring of ambient air likely results in misclassification of the true exposure, the negative findings of this study must be interpreted cautiously.

Air Pollutants↗
PubMed1987

Effect on birth weight of erythromycin treatment of pregnant women.

To test the hypothesis that treatment with antibiotics prevents low birth weight, pregnant women whose vaginal cultures contained Ureaplasma urealyticum or Mycoplasma hominis (or both) and who gave written informed consent were treated with one of the following: identical looking capsules containing 250 mg of either erythromycin estolate or stearate (active against U urealyticum), or 150 mg of clindamycin hydrochloride (active against M hominis), or placebo, four times daily for six weeks in a randomized double-blind study. Treatment with clindamycin had no effect. Treatment with erythromycin initiated during the second trimester had no effect on mean birth weight or on the frequency of low-birth-weight infants. In contrast, women whose treatment with erythromycin was initiated in the third trimester gave birth to infants with a heavier mean birth weight (3331 g) than infants born to placebo-treated women (3187 g) (P = .042). Similarly, in women whose erythromycin was begun during the third trimester, the birth rate of infants weighing 2500 g or less was 3%, whereas in women treated with placebo, the birth rate for low-birth-weight infants was 12% (P = .047). These data suggest that treatment with erythromycin during the third trimester prevents low birth weight in mycoplasma-colonized pregnant women. Whether the effect is due solely to the action of erythromycin on U urealyticum is uncertain.

Birth Weight↗
PubMed1987

Electrophysiological effects of penticainide in the anaesthetized dog.

The cardiac electrophysiological effects of Penticainide, a new antiarrhythmic agent, were studied by means of intracardiac electrodes in the anaesthetized dog. Intravenous administration of 5 mg/kg of Penticainide reduced the sinus rate and prolonged the sinus node recovery time. Atrial refractory periods increased. Anterograde intranodal conduction slowed and nodal refractoriness increased. Conduction time in the His-Purkinje tissue and ventricle increased, as did the ventricular refractory periods. Monophasic action potential duration was not altered by the drug in the atrium or the ventricle. The mechanism of action of Penticainide as an antiarrhythmic drug seems to be correlated to its membrane effects: inhibition of the fast-inward current, responsible for the marked effects on His-Purkinje and ventricular tissues; and inhibition of the slow-inward current, suggested by its effects on sinus node and atrio-ventricular node.

Action Potentials↗
PubMed1985

[Mode of action of purinergic derivatives of adenine on auriculo-ventricular conduction. Experimental study in dogs].

The effects of three purine derivatives of adenine, adenosine triphosphate (Striadyne), purified adenosine triphosphate and adenosine, on conduction tissue, were studied in closed chest dogs with endocavitary recording catheters. The dogs were anaesthetised with pentobarbital and ventilated, then three bipolar catheters were positioned to allow atrial pacing and recordings of atrial and His bundle potentials. The purines studied were administered by rapid bolus intravenous injection. The dosage was identical based on a predetermined dose-response curve (dose of 2 mg/kg). The study of the effects on atrioventricular conduction was carried out before and after administration of antagonists: atropine, 0.08 mg/kg and aminophylline, 10 mg/kg. Twelve dogs were studied for each purine: 6 with initial premedication with atropine and then aminophylline, and 6 with the inverse sequence. Lengthening of AV conduction was due exclusively to nodal depression. No variation in the HV interval was observed (HV = 35 +/- 4 ms). Lengthening of AH interval was observed very soon after injection of the drugs (5 to 10 seconds) with a peak effect between 20 and 40 seconds. Reversion to the initial value always occurred in under 2 minutes. In the model studied, Striadyne and purified adenosine triphosphate were much more powerful than adenosine, both in intensity and duration; high degree AV block was obtained in 10 out of 12 cases with Striadyne and in 8 out of 12 cases with purified adenosine triphosphate, but in only 2 out of 12 cases with adenosine. The use of specific antagonists demonstrated the different modes of action of the three purines.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1984

Therapeutic use of adenosine for terminating spontaneous paroxysmal supraventricular tachycardia.

Intravenous adenosine proved effective in eight out of ten episodes of acute spontaneous supraventricular tachycardia. AV node blockade induced by adenosine occurred 20 s after injection, and disappeared very quickly. Side-effects were transient and never serious. Therefore, it is thought that adenosine can be proposed safely for the short-term treatment of supraventricular tachycardia. Because of the different mechanisms of action, the specific side-effects observed after ATP administration are unlikely to be encountered.

Adenosine↗
PubMed1984

Airways responsiveness in a population sample of adults and children.

Nonspecific bronchial responsiveness was assessed with eucapneic hyperpnea to subfreezing air in a population-based sample of 134 adults and 213 children in East Boston, Massachusetts. Increased responsiveness was considered to be present if the decrease in forced expiratory volume in one second with cold air divided by the initial vital capacity was greater than 9%. Men and women had similar bronchial responsiveness, but children and young adults (24 yr of age and younger) were significantly more likely to be responders than were older subjects (p less than 0.001). Children with a doctor's diagnosis of asthma at any time in the past were twice as likely (42.9%) to be responders as were nonasthmatic children (19%) (p = 0.004). Ninety-two percent (11/12) of currently active asthmatics were responders. However, a large percentage of asymptomatic children had increased levels of bronchial responsiveness (18.9%). This cross-sectional study demonstrates the feasibility of measurement of nonspecific bronchial responsiveness in epidemiologic studies, and its relationship to age and wheeze symptoms in children.

Adult↗