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Biomedical subjects

E S Jacobson

Publications and source records attributed to E S Jacobson.

51 records · Page 3Linked to original sources
PubMed1981

Auxotrophic markers and the cytogenetics of Filobasidiella neoformans.

In the sexual phase of Cryptococcus neoformans four post-meiotic nuclei give rise to the nuclei of four long chains of basidiospores. If there is fixed relationship between one post-meiotic nucleus and one chain the result should be genetic homogeneity within single chains; random composition of chains would represent the opposite case. We tested for homogeneity in single chains from crosses of niacin-auxotrophs to the wild type by dissecting single chains of basidiospores from mature fruiting bodies. Out of 14 chains, 11 were homogeneous; the probability of obtaining this result by random processes was less than 0.01. These results suggest that mitotic products of a particular post-meiotic nucleus may be channeled into a particular basidiospore chain.

Cryptococcus↗
PubMed1981

Selenocystine-resistant mutants of Histoplasma capsulatum.

Cysteine metabolism has been thought to be important to the phenomenon of dimorphism in Histoplasma capsulatum. We sought mutants with genetic blocks in the metabolism of cysteine by selection of colonies resistant to the toxic analogue, selenocystine. The 22 resistant strains thus obtained were all deficient in uptake of cystine from the surrounding medium but were normally able to convert from mycelium to yeast and back again. Furthermore, they had normal quantities of NADH-dependent cystine reductase when this enzyme was measured. We conclude that mutants defective in cystine uptake can be readily obtained by selection of colonies resistant to selenocystine, and that a lesion in cystine-uptake does not appear to affect the phenomenon of dimorphism in this organism.

Cystine↗
PubMed1977

Trichinosis in an immunosuppressed human host.

The clinical presentation and autopsy findings in the case of a patient with acute myelomonocytic leukemia and trichinosis are described. Cellular immunity is an important host defense against nematode infections such as strongyloidiasis. It is therefore probable that the severe trichinosis seen in this immunosuppressed patient was more than coincidental. Due to concomitant failure of humoral immunity, serodiagnosis of trichinosis would have been impossible. The only means of making the diagnosis antemortem would have been muscle biopsy.

Female↗
PubMedDate not supplied

Discordant regulation of phenoloxidase and capsular polysaccharide in Cryptococcus neoformans.

We examined the regulation of two fungal virulence factors, phenoloxidase and capsular polysaccharide, in an ex-type strain of the fungal pathogen, Cryptococcus neoformans. Both were made during the stationary phase of cultural growth. Exogenous iron increased phenoloxidase activity three-fold (from 8.7 to 27.7 units mg-1, P < 0.05) but decreased capsular polysaccharide three-fold (from 9.0 to 3.4% packed cell volume, P < 0.01). A temperature shift from 25 to 37 degrees C decreased phenoloxidase activity three-fold (from 60.6 to 23.7 units mg-1, P < 0.01) but not capsular polysaccharide (8.5 to 6.7% packed cell volume, P not significant). Thus, cryptococcal virulence factors are not regulated coordinately. Moreover, although the phenoloxidase synthesizes an antioxidant, melanin, the enzyme is not induced by the oxidant, hydrogen peroxide, or by a combination of hydrogen peroxide and solubilized ferric ion. As cryptococcal melanin is cheaply made from exogenous catechols, perhaps C. neoformans does not need to regulate the phenoloxidase strongly but, rather, can afford to synthesize the phenoloxidase at a moderate rate whenever it finds its growth limited.

Cryptococcus neoformans↗
PubMedDate not supplied

The spectrum of histoplasmosis in a general hospital: a review of 55 cases diagnosed at Barnes Hospital between 1966 and 1977.

Between 1966 and 1977, 55 patients at Barnes Hospital were proven to have manifestations of histoplasmosis. Five patients had acute pulmonary histoplasmosis, four of whom demonstrated unusually severe disease. Disseminated histoplasmosis was documented in 19 cases. Four of these patients demonstrated dissemination during a severe and protracted but self-limited illness. The other 15 patients had progressive disease. Most of these patients were immune compromised and presented with fever of unknown origin. Therapy most benefited those who completed a course of greater than or equal to 1.5 gm of amphotericin B. Chronic pulmonary histoplasmosis was documented in 14 individuals. Large (> 1.5 cm), solitary pulmonary coin lesions, excised from 14 patients, were found to consist of exuberant granulomas containing yeast. Organisms were recovered from pleural effusions of two patients and demonstrated histologically in the tissue of one individual who presented with fibrosing mediastinitis.

Adolescent↗
PubMedDate not supplied

Reevaluation of diagnostic histoplasma serologies.

There are few quantitative guidelines for the interpretation of serologic tests for histoplasmosis. Furthermore, guidelines that have been proposed are not accepted generally. This report reviews experiences with complement fixation and latex agglutination tests performed in a large acute-care hospital in an endemic area, and depicts the relationship between the proportion of false-positive reactions and the titer at which the serologic tests were reactive. We noted a considerable number of false-positive reactions for these widely-used tests. Use of a battery of standard tests for histoplasmosis resulted in a 90% decrease in false-positive reactions. Reliance upon multiple positive results in such a battery of tests would result in failure to detect 50% of cases of disseminated histoplasmosis, but would eliminate most false positives.

Complement Fixation Tests↗