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Biomedical subjects

J C Rhodes

Publications and source records attributed to J C Rhodes.

7 recordsLinked to original sources
PubMed1992

Detection of cryptococcal antigen in bronchoalveolar lavage fluid: a prospective study of diagnostic utility.

Cryptococcal pneumonia is associated with significant morbidity and mortality in immunocompromised patients. We examined the utility of screening bronchoalveolar lavage (BAL) fluid for cryptococcal antigen. In a pilot study, we found that cryptococcal antigen was always positive in unprocessed BAL specimens of seven patients with cryptococcal pneumonia and negative in 44 patients with other granulomatous diseases who acted as the control subjects. A prospective study was done of 220 immunocompromised patients (188 with human immunodeficiency virus infection, 32 with other causes of immunosuppression) undergoing BAL for fever and pulmonary symptoms. The eventual diagnosis of cryptococcal pneumonia was made in eight patients. All eight patients had a cryptococcal antigen titer greater than or equal to 1:8. There were four patients without cryptococcal pneumonia who had cryptococcal antigen titers of 1:8, there were none with higher titers. For a titer of cryptococcal antigen titer of greater than or equal to 1:8, there was 100% sensitivity, 98% specificity, a positive predictive value of 67%, and a negative predictive value of 100%. The measurement of cryptococcal antigen in the BAL can be a rapid, simple way to make a diagnosis of cryptococcal pneumonia in immunosuppressed patients with pneumonia.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Antigenicity and immunogenicity of an extract from the cell wall and cell membrane of Histoplasma capsulatum yeast cells.

In order to identify T-cell antigens from Histoplasma capsulatum yeast cells, we prepared a detergent extract of the cell wall and cell membrane of yeast-phase H. capsulatum G217B and analyzed its antigenicity and immunogenicity. Mice injected with viable H. capsulatum yeast cells or with 500 or 1,000 micrograms of the extract mounted a delayed-type hypersensitivity response to solubilized cell wall and cell membrane. Vaccination with this antigenic preparation conferred a protective immune response in mice that were challenged intravenously with H. capsulatum yeast cells. The extract induced in vitro proliferation by splenocytes from mice injected with either viable yeast cells or the soluble cell wall and cell membrane preparation. We also examined the profile of in vitro responses by a murine T-cell line and by cloned T cells to soluble cell wall and cell membrane by employing the technique of T-cell immunoblotting. Two prominent regions that stimulated the T-cell line and cloned T cells were identified. Fractions encompassing an area between 53 and 64 kDa caused proliferation by a T-cell line and five of six clones. Antigens recognized by the T-cell line and by three of six clones were contained in another area that extended from 69 to 82 kDa. The data demonstrate that this soluble extract from cell wall and cell membrane contains antigens recognized by T cells and mediates protective immunity. Moreover, T-cell immunoblotting provides a useful technique for mapping immunoreactive molecules from H. capsulatum yeast cells.

Animals↗
PubMed1991

The elastinolytic proteinase of Aspergillus flavus is not glycosylated.

Aspergillus flavus produces an elastinolytic metalloproteinase in culture fluid which does not appear to be a glycoprotein. The elastase did not stain with periodic acid Schiff reagent, its migration rate was not changed by digestion with glycosidases or chemical agents, and its release into culture medium was not inhibited by tunicamycin.

Animals↗
PubMed1990

Experimental murine invasive pulmonary aspergillosis.

A new model of invasive pulmonary aspergillosis (IPA) was developed in immunosuppressed mice. Intranasal route of inoculation was used to deliver predictable numbers of Aspergillus flavus conidia. The LD50 was determined to be 2.7 X 10(2) viable conidia, and a combination of quantitative culture and determination of chitin content was shown to best measure the progression of pulmonary disease. The evolution of IPA in these mice conformed with what has been reported in human cases of aspergillosis; both histopathology of the pulmonary lesions and dissemination pattern resembled their human counterparts. The authors hope to use this model to study virulence mechanisms of Aspergillus and novel therapeutic methods.

Administration, Intranasal↗
PubMed1990

Isolation and characterization of an elastinolytic proteinase from Aspergillus flavus.

An elastinolytic proteinase of Aspergillus flavus has been isolated to homogeneity, and its physical and biochemical properties have been characterized. Two purification protocols were compared; an initial step of ion-exchange chromatography was found to be equivalent to ammonium sulfate precipitation at neutral pH. A combination of gel filtration and adsorption chromatographies on the resultant crude enzyme produced highly purified elastase with yields of 5 to 10%. The enzyme is a 23-kilodalton protein with a pI of 7.6. The enzyme activity is markedly inhibited by numerous metal ions. Aspergillus elastase appears to be a metalloproteinase EC 3.4.24.X), as determined by its sensitivity to 1,10-phenanthroline.

Aspergillus flavus↗
PubMed1975

Comparison of four methods for determining nitrate utilization by cryptococci.

This study evaluated the following methods for determining nitrate utilization: Wickerham broth, a special nitrate broth, Delft plate, and nitrate strip. With 236 isolates of cryptococci as test organisms, the special nitrate broth method gave 99% correct results and the Wickerham broth method gave 98%. The nitrate strip and Delft plate methods gave correct results in 94 and 86% of tests, respectively. The special nitrate broth method is judged superior because it provides accurate results within 48 h, compared to 14 days with the Wickerham broth method.

Cryptococcus↗