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Biomedical subjects

J C Rhodes

Publications and source records attributed to J C Rhodes.

45 records · Page 3Linked to original sources
PubMed1981

Clinical evaluation of the AutoMicrobic system Yeast Biochemical Card for rapid identification of medically important yeasts.

The autoMicrobic system Yeast Biochemical Card (Vitek Systems, Inc., subsidiary of McDonnell Douglas, Hazelwood, Mo.), a fully automated and computer-assisted method for identifying seven yeast genera based on 26 biochemical reactions, was compared with the API 20C (Analytab Products, Plainview, N.Y) yeast identification system, using 253 clinical yeast isolates. There was an 84% correlation between the Yeast Biochemical Card and API 20C systems based on biochemical tests alone and a 96% correlation when morphology was combined with the biochemical profile. Of 22 species examined, 14 were definitively identified within 24 h, using only the biochemical tests; the remaining 8 species were presumptively identified, using biochemical tests within 24 h, with definitive identification being completed in 48 to 72 h when morphological characteristics were ascertained. The Yeast Biochemical Card system was both a facile and, with concomitant morphology, an accurate system for performing yeast identification.

Autoanalysis↗
PubMed1981

Quantification of naphthyl conjugates. Comparison of high-performance liquid chromatography and selective enzyme hydrolysis methods.

1. An h.p.l.c. method for the simultaneous determination of naphthol, naphthyl glucuronide and naphthyl sulphate in urine is described. This procedure is based on the selective formation of an ion pair between the sulphate conjugate and tetrabutyl lammonium, which allows its resolution from the glucuronide on a reverse phase column. 2. The h.p.l.c. method is sed to assess the selective enzyme hydrolysis method which is frequently employed in drug conjugate assays. Results suggest that the use of sulphatase and beta-glucuronidase may give data which are quantitatively and qualitatively erroneous.

Animals↗
PubMed1980

Isolation and characterization of arginine auxotrophs of Cryptococcus neoformans.

Arginine auxotrophs were isolated in both mating types of Cryptococcus neoformans. In both mutants, the auxotrophy was due to the lack of active argininosuccinate lyase. The virulence in mice of the mutants was compared with that of the wild type. One auxotroph displayed a loss of virulence which appeared to be related to the presence of another mutation, one which prevented normal cell separation after budding. The other auxotroph had reduced virulence compared with the wild type, but a variant isolated from it by mouse passage had virulence equivalent to that of the wild type while maintaining the auxotrophic requirements.

Animals↗
PubMed1980

Genetic control of susceptibility to Cryptococcus neoformans in mice.

Inbred mice injected intravenously with 5 x 10(6) cells of Cryptococcus neoformans showed two patterns of survival: sensitive (A/WySn, A.BY, A/J, DBA/2J, NZB/B1NJ, and SWR/J) and resistant [C57BL/10Sn, B10.A, B10.A (2R), B10.S (7R),C57BR/cdJ, C58/J, C3H/HeJ, BALB/c, DBA/1J, and SJL/J]. Relative susceptibility based on survival time was shown to correspond to differences obtained for 50% lethal dose values. Either decreasing the dose of organisms or changing to the intraperitoneal route of inoculation resulted in prolonged survival times, but neither change affected the observed patterns of survival. F1 hybrids between different sensitive strains were also sensitive, whereas F1 hybrids between sensitive and resistant strains were resistant, indicating a dominant mode of inheritance. Sensitivity and resistance were shown to be under single gene control by segregation analysis in F2 progeny produced by inbreeding (B10.A x A/WySn)F1 hybrids and in (F1 x A/WySn) backcross progeny. Blood obtained from parental strains, F1, F2, and backcross hybrids was tested for the presence or absence of hemolytic complement. Mice lacking hemolytic complement activity in their sera are homozygous for the Hc(0) allele at the Hc locus on chromosome 2 and are deficient in the complement component C5. A 1:1 correspondence was found between C5 deficiency and sensitivity to C. neoformans. Resistance was shown to cosegregate with the presence of hemolytic complement in the F2 and the backcross progenies.

Animals↗
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↗
PubMedDate not supplied

Antipyrine metabolite kinetics in rats: studies on dose and time dependence.

Antipyrine metabolite kinetics have been investigated in the rat with respect to dose and time dependence. The metabolic pathways, 4-hydroxylation, benzylic oxidation, and N-demethylation, are of equal quantitative importance (approximately 20 per cent of dose) and show no dose dependence over the range 25-500 mg kg-1. By using [N-methyl-14C]-antipyrine, the single carbon fragment lost by N-demethylation may be monitored as 14CO2. Serial sampling of 14CO2 exhalation rate provides a half-life estimate which, according to theoretical principles, reflects the antipyrine plasma half-life. When both half-lives were measured in the same animals a statistically significant correlation was evident. At doses of 250 mg kg-1 and 500 mg kg-1 there is an increase in CER half-life (218 and 303 min respectively) when compared to a dose below 100 mg kg-1 (152 min). The metabolite formation rate constants are decreased accordingly at the high doses but are invariant over the dose range 25-100 mg kg-1. Although inter-rat variation in antipyrine metabolite kinetics was substantial, intra-rat variability was small. The noninvasive nature of determining antipyrine metabolite kinetics via breath and urine analysis provides a potentially useful animal model system to investigate the factors influencing hepatic mixed function oxidase activity in vivo.

Animals↗
PubMedDate not supplied

Ovarian volume and menopausal status.

OBJECTIVE: The purposes of this study were to (1) examine whether ovarian volume differs by age and menopausal status in healthy women; (2) evaluate whether ovarian volume could be a sensitive and specific predictor of menopausal status; and (3) assess whether ovarian volume is affected by cigarette smoke, oral contraceptives (OCs), and hormone replacement therapy (HRT). DESIGN: Each participant (527 women) completed an extensive in-home interview that assessed age, menopausal status, smoking history, OC use, and HRT use. Each participant also received a transvaginal ultrasound that measured ovarian volume. Geometric means for ovarian volume were compared between premenopausal and postmenopausal women using t tests. Tests for trends were conducted using linear regression analyses. RESULTS: Ovarian volume declined with age (p < or = 0.0001) and also differed by menopausal status; postmenopausal women had smaller ovarian volumes than premenopausal women of the same age (p < or = 0.0001). Ovarian volume was not associated with smoking history or HRT use. However, it was significantly smaller in current users of OCs compared with past users of or those who never used OCs (p < or = 0.0001). Ovarian volume was a sensitive and specific predictor of postmenopausal status. CONCLUSIONS: The data suggest that age, menopausal status, and OC use may be determinants of ovarian volume. They also suggest that ovarian volume may be useful for predicting menopausal status in women.

Adult↗