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J D Dick

Publications and source records attributed to J D Dick.

42 records · Page 3Linked to original sources
PubMed1983

Evaluation of an automated fluorescence polarization immunoassay for vancomycin.

An automated fluorescence polarization immunoassay for the determination of vancomycin levels in serum was evaluated. The vancomycin assay is a homogeneous competitive inhibition immunoassay based on changes in fluorescence polarization that occur with antibody binding. This assay was compared with a liquid chromatographic assay and an agar well diffusion bioassay method by using clinical serum specimens and controls. Linear regression analysis of the data obtained on clinical specimens by the three methods resulted in correlation coefficients of 0.97 for the fluorescence polarization immunoassay versus the liquid chromatographic assay (n = 60), 0.90 for the fluorescence polarization immunoassay versus the bioassay (n = 57), and 0.90 for the liquid chromatographic assay versus the bioassay (n = 57). Repetitive analysis of control sera containing 7, 35, and 75 micrograms of vancomycin per ml by the fluorescence polarization immunoassay yielded coefficients of variation of 3.0, 1.7, and 2.3, respectively. No interference was demonstrated in spiked hemolytic, lipemic, or icteric sera, and the assay was free of matrix effects. The automated fluorescence polarization immunoassay system offers a rapid, efficient, and accurate method for monitoring vancomycin serum levels for both toxicity and efficacy.

Biological Assay↗
PubMed1982

Differences in virulence of clinical isolates of Candida tropicalis and Candida albicans in mice.

Prior reports from this institution indicated that Candida tropicalis was more pathogenic than C. albicans in oncology patients. Pairs of clinical isolates of C. tropicalis and C. albicans recovered from similar patients at other institutions were examined to determine their relative virulence. After intravenous inoculation in normal mice, three pairs of isolates had no significant differences in the 50% lethal dose, and one C. tropicalis isolate was less virulent than its companion C. albicans isolate. In contrast, in mice treated with antibiotics and cytarabine, an antineoplastic drug which damages the gastrointestinal mucosa and produces granulocytopenia, oral inoculation of yeast cells produced striking differences in the 50% infective dose: each C. tropicalis isolate was more virulent than the companion C. albicans isolate from the same institution. The increased virulence of the C. tropicalis isolates compared with the C. albicans isolates when given orally to compromised mice parallels clinical observations in compromised patients.

Agranulocytosis↗
PubMed1980

Incidence of polyene-resistant yeasts recovered from clinical specimens.

The development of resistance to amphotericin B and nystatin in yeast isolates was determined. Organisms recovered from patients on the oncology service, undergoing extensive chemotherapy for acute leukemia and bone marrow transplantation, were compared with yeasts recovered from patients on other services in the same hospital over a 7-month period. An agar dilution method was used to assay the susceptibility for each antibiotic; resistance was defined as a minimal inhibitory concentration of greater than or equal to 2 micrograms/ml for amphotericin B and greater than or equal to 16 micrograms/ml for nystatin. None of 625 isolates from 238 patients on non-oncology services demonstrated polyene resistance. Resistance only occurred in a subpopulation of oncology patients, in which 55 isolates (7.4%) from six patients (8.6%) exhibited polyene resistance. Resistance yeasts included Candida albicans (three strains), Candida tropicalis (one strain), and Torulopsis glabrata (two strains). All of the patients from whom resistant yeasts were recovered had experienced extensive chemotherapy with cytotoxic agents, granulocytopenia, and long-term treatment with both antibacterial and polyene antibiotics. Resistance to 2 micrograms of amphotericin B per ml and to 16 micrograms of nystatin per ml was associated with loss or marked depression of ergosterol in the cell membrane as measured by ultraviolet spectra. A significant incidence of polyene resistance in an oncology subpopulation was documented, suggesting a need for susceptibility testing in patients who are at high risk for development of drug-resistant fungal pathogens.

Amphotericin B↗
PubMed1980

Pathogenicity of Candida tropicalis and Candida albicans after gastrointestinal inoculation in mice.

The ability of clinical isolates of Candida albicans and candida tropicalis to invade through normal and damaged gastrointestinal mucosa was determined. Adult mice were treated with either gentamicin or gentamicin and cytarabine. Suspensions of yeast cells (10(7)) were administered through a catheter intraesophageally. Invasion was determined by culturing liver, kidney, and lung tissue from mice sacrificed after 48 h. C. albicans and C. tropicalis were incapable of invading through normal gastrointestinal mucosa in mice treated only with gentamicin. Two isolates of C. tropicalis penetrated the damaged gastrointestinal mucosa in 69% (49 of 71) of mice treated with gentamicin and cytarabine. In contrast, three isolates of C. albicans penetrated he damaged gastrointestinal mucosa in only 23% (14 of 62) of mice. These results suggest that C. tropicalis is more capable of invading through damaged gastrointestinal mucosa than C. albicans. The observations in this mouse model parallel those seen in patients on cytotoxic drugs. Therefore, this model offers a tool for investigation of the pathogenicity of these organisms in a model analogous to the compromised host.

Animals↗
PubMedDate not supplied

Septic reactions to platelet transfusions. A persistent problem.

OBJECTIVE: To determine the medical and laboratory characteristics of bacteremia secondary to transfusion of microbiologically contaminated platelet concentrates. DESIGN: Febrile transfusion reactions were prospectively monitored over 42 months. Units involved in reactions were evaluated with Gram's stain and culture tests. SETTING: Comprehensive cancer center. PATIENTS: Patients receiving platelet transfusions for thrombocytopenia secondary to bone marrow failure. RESULT: Seven cases of transfusion-associated sepsis were observed. Multidonor platelet products stored for 5 days resulted in an incidence of sepsis five times higher than those stored for 4 days or less (P less than .01). Investigation indicates that contamination most likely occurred at the time of blood collection. Clinically, septic reactions were associated with greater temperature elevations (average increase, 2.0 degrees C) than febrile reactions to sterile products. CONCLUSIONS: Contamination of platelet concentrates remains a significant clinical problem. Septic episodes may be reduced by transfusion of platelets with shorter storage intervals.

Adult↗