The Distribution of Perkinsus marinus in Gulf Coast Oysters: Its Relationship with Temperature,Reproduction, and Pollutant Body Burden

Oysters from 48 Gulf of Mexico sites were examined for presence and infection intensity of the endoparasite, Perkinsus (= Dermocystidium) marinus (Mackin, Owen and Collier, 1950) as part of NOAA's Status and Trends Mussel Watch Program. Prevalence exceeded 75% at 25 sites. Infection intensity did not vary with sex or reproductive stage. Latitude, total polynuclear aromatic hydrocarbon (PAH) content and industrial and agricultural land use significantly affected the parasite's distribution. PAH and pesticide concentrations were latitudinally dependent, suggesting an impact of spawning frequency on uptake and depuration. P. marinus analysis complements the use of pollutant body burden for determining change in environmental quality because it responds differently than pollutant body burden to the biology and ecology of the oyster.     

Changes in lung permeability and lung mechanics accompany homeostatic instability in senescent mice.

Aging and lung disease are recognized factors that increase mortality risk in subjects exposed to ambient particulate matter (PM). In an effort to understand the mechanisms of enhanced susceptibility, the present study examined an inbred mouse model of senescence to 1) determine changes in lung permeability as animals approach the end-of-life and 2) characterize age-dependent changes in lung mechanics in presenescent and terminally senescent mice. The clearance of technetium-99m (99mTc)-diethylenetriamine pentaacetic acid (DTPA) was used to test the hypothesis that lung permeability increases with age and enhances uptake of soluble components of PM principally during the period several weeks before death in AKR/J mice. Quasistatic pressure-volume curves were conducted on robust and on terminally senescent AKR/J mice several weeks before death to assess the relative importance of lung mechanics. Abrupt body weight loss was used to signal imminent death because it accompanies indexes of physiological aging and terminal senescence. 99mTc-DTPA clearance from the lung 30 min after tracheal instillation was significantly (P < 0.05) enhanced in senescent mice. Age-dependent changes in lung mechanics were indicative of significant (P < 0.05) decrements in lung volume and compliance several weeks before death. Thus, during a period of homeostatic instability leading toward natural death, AKR/J mice showed enhanced permeability of soluble particles despite a decrease in lung volume and concomitant alveolar surface area. These results suggest that pulmonary epithelial-endothelial barrier dysfunction occurs in terminally senescent mice just before death. Furthermore, this senescent-dependent increase in lung permeability may be a contributing factor for increased PM susceptibility in the elderly and patients with lung disease.     

GELATINASE AND THE GATES-GILMAN-COWGILL METHOD OF PEPSIN ESTIMATION

The Gates photographic film method for pepsin estimation as developed by Gilman and Cowgill measures an activity corresponding to that determined by the hemoglobin method of Anson and Mirsky rather than that resulting from the use of the gelatin viscosity technique. Therefore, the presence of gelatinase is not a source of great error in the gelatin film procedure.     

Studies on histoplasmosis I. Comparative virulence of variant and parent strain Histoplasma capsulatum in Hamsters

Summary 1. A variant strain ofHistoplasma capsulatum was isolated from a secondary colony in cultures of tissue from hamsters infected with the parent strain ofHistoplasma. The variant strain was found to differ from the parent strain in colonial morphology, stability of the yeast phase in subculture, and in growth rate.2. Results of virulence testing with these two strains showed the parent strain to be somewhat more virulent than the variant strain as measured by survival time and slope of the death rate curve over a 19 day period.3. Nevertheless, in view of the more rapid growth rate of the variant and its probable antigenic variation from the parent strain, the development of such a variant is viewed as an increased hazard to the host, particularly in a longer term infection.4. The repeated isolation of a variant strain ofHistoplasma suggests that strain variation may play a significant role in the outcome of naturally acquired infections.This work was initiated at the State University of New York, Downstate Medical Center, Brooklyn, N. Y., and supported in part by funds ((#12-1081) from the National Fund for Medical Education, grant # 12-1054.