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Biomedical subjects

J L Levin

Publications and source records attributed to J L Levin.

43 records · Page 3Linked to original sources
PubMed1980

Reversal of 5HT-induced bronchoconstriction by PGI2: distribution of central and peripheral actions.

In anesthetized, mechanically ventilated, and vagotomized cats, we studied the distribution of the bronchodilatory effects of prostaglandin I2 (PGI2) in central and peripheral airways. In the intact-chest cat, bolus intravenous injection of PGI2 in a range of doses from 3 to 100 micrograms produced dose-dependent reversal of 5-hydroxytryptamine- (5HT) induced bronchoconstriction. Bronchodilatory effects were manifested by a pronounced decrease in central airways flow resistance, as estimated by measurement of lung resistance and by an increase in dynamic lung compliance (Cdyn). A similar distribution and magnitude of airway effects were produced by intravenous administration of PGE1 in a range of doses from 0.3 to 10 micrograms. PGI2 significantly reversed the frequency dependence of compliance induced by infusion of 5HT. The PGI2 metabolite, 6-keto-PGF1 alpha, was without effect on pulmonary mechanics. Comparison of right- versus left-heart administration of PGI2 did not point to a significant role of the bronchial circulation in the airway effects of PGI2. Comparison of the effects of PGI2 and PGE1 on cat bronchial and parenchymal strips contracted by 5HT showed both prostaglandins to have predominant action on bronchial smooth muscle with PGI2 being 3-10 times less active than PGE1. These data suggest that PGI2 has central airway bronchodilator activity, similar to, but less potent than PGE1. In addition, they suggest that PGI2 has significant dilator activity in certain peripheral areas of the lung, as well.

Animals↗
PubMed1980

Differential actions of the prostaglandins on the pulmonary vascular bed.

We have reported that administration of cyclooxygenase inhibitors such as indomethacin and meclofenamate results in a slow gradual increase in pulmonary vascular resistance in the intact dog (21). It has been shown that a PGI2, "like" substance is continually released by the lung (6). We have, therefore, suggested that under resting conditions, the pulmonary vascular bed is maintained in a dilated state by production of a vasodilator product in the cyclooxygenase pathway (10,21). Recent evidence suggests that this vasodilator product in the cyclooxygenase pathway is a PGI2 'like" substance (6,13,20).

Animals↗
PubMedDate not supplied

An individual with a majority of ferruginous bodies formed on chrysotile cores.

A 59-year-old man was exposed to chrysotile asbestos while rebuilding clutches. Analytical electron microscopy showed a chrysotile core in 72% of the ferruginous bodies from lung tissue. Long, uncoated chrysotile fibers were also present. Sufficient exposure to long chrysotile in jobs such as this appears to allow the majority of ferruginous bodies to be formed on chrysotile, an exception to the rule that most ferruginous bodies form on amphibole cores.

Asbestos, Serpentine↗
PubMedDate not supplied

Azoospermia and oligospermia among a large cohort of DBCP applicators in 12 countries.

Azoospermia and oligospermia have been well demonstrated among workers exposed to 1,2-dibromo-3-chloropropane (DBCP) in manufacturing and formulation of this pesticide. After DBCP was banned in the United States in the late 1970s, two American companies continued to export it to many less developed countries. In the early to mid-1990s, attorneys assembled a cohort of approximately 26,400 male plaintiffs who, as workers on banana and pineapple plantations in 12 of these countries, had been exposed to DBCP, primarily during its application. These attorneys, for the purpose of a lawsuit against the two American companies, developed from interrogatories a database on these men that included information about stated periods of occupational DBCP exposure. Seminal fluid analysis results were also entered into the database. Analyzing information in this database, the authors found that, after a median exposure to DBCP of three years, 64.3% of these men overall, and 90.1% of men studied from the Philippines, had azoospermia or oligospermia. The mean number of children reported by the men was 2.5 overall. The percentage of men with no children was 28.5% overall. This report represents the largest cohort of DBCP-exposed workers in which adverse reproductive health effects have been described, and the first report of the adverse effects on the reproductive health of workers exposed to DBCP primarily through its application in a cohort of this size. This serious and extensive occurrence of adverse reproductive health effects due to the export of a hazardous pesticide before and after its ban in the United States illustrates a number of needs for monitoring, research, education, and policy development.

Adolescent↗