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Biomedical subjects

G L Dorn

Publications and source records attributed to G L Dorn.

At least 19 recordsLinked to original sources
PubMed1991

Microbial stabilization of antibiotic-containing urine samples by using the FLORA-STAT urine transport system.

The FLORA-STAT Urine Transport System (Wadley Biosciences Corp./Lymphokine Partners Ltd., Dallas, Tex.) was evaluated for its efficacy in maintaining organism count and in effectively blocking the bactericidal action of therapeutic antimicrobial agents in urine samples when the urine samples were held at room temperature. Reconstructions with 53 organism-antimicrobial combinations were performed at 0, 4, 8, and 24 h in which the FLORA-STAT system was compared with two boric acid-based systems (Urine C&S Transport Kit [Becton Dickinson VACUTAINER Systems, Rutherford, N.J.]; Sage Urine Collection Kit for Culture [Sage Products, Inc., Cary, Ill.]) and untreated urine. At 24 h, less than 1-log-unit changes in organism counts were found in 100, 92, and 10% of the urine samples without antimicrobial agents and in 97, 65, and 16% of the urine samples with antimicrobial agents for FLORA-STAT-treated, boric acid-treated, and untreated urine samples, respectively. The FLORA-STAT system was further evaluated by sending split samples prepared from laboratory-inoculated patient urine samples (57 without and 50 with antimicrobial agents) to four commercial laboratories by using their respective transport devices and procedures. Samples were also sent to a local reference laboratory which provided prompt processing. Each laboratory received independently labeled transport devices containing untreated, FLORA-STAT-treated, and preservative-treated (if provided by the commercial laboratory) samples prepared from the same urine specimen of a patient. Average estimated transport times ranged from 13 to 24 h for the commercial laboratories; the transport time was less than 4 h for the local reference laboratory.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1987

Evaluation of SOC for the presumptive identification of Candida albicans and Cryptococcus neoformans.

SOC, a fungal growth medium composed of Solryth, oxgall, and caffeic acid, was evaluated as a medium to provide rapid, differential identification of Candida albicans and Cryptococcus neoformans. Using a variety of common isolation media to produce the yeast inocula, the germ tube methods tested ranked in the following order of decreasing sensitivity: SOC (97% +/- 1), serum (92% +/- 5), rabbit coagulase plasma with EDTA in combination with tryptic soy broth (89% +/- 5), TOC (89% +/- 6), and rabbit coagulase plasma with EDTA (83% +/- 4). In chlamydospore production, SOC also proved to be the most sensitive after 24 h incubation: SOC (96% +/- 2), TOC (80% +/- 2), and cornmeal-Tween 80 agar (14% +/- 3). Other medically important yeasts showed normal patterns of growth within 24 h on SOC, thus assisting in their identification. Eighty strains of Cryptococcus neoformans showed characteristic brown pigmentation on SOC and TOC within 18 h, while all other species of the genus Cryptococcus and 229 Candida isolates did not show a change in pigmentation.

Candida albicans↗
PubMed1979

Improved blood culture technique based on centrifugation: clinical evaluation.

A total of 3,335 blood samples from 1,180 patients suspected of having bacteremia were analyzed concurrently by two methods: (i) supplemented peptone broth with sodium polyanethanol sulfonate and a CO2 atmosphere; and (ii) lysis centrifugation at 3,000 X g for 30 min onto a high-density, hydrophobic cushion. The centrifugation technique recovered 80% of the positive cultures as compared with 67% for the broth method. The centrifugation technique showed an apparent increase in the isolation of staphylococcus aureus, Pseudomonas, and yeasts. In almost every instance, the time required for detection of a positive culture was shortest for the centrifugation method. Contamination rates for both systems were comparable (1.4%). Quantitation, offered only by the centrifugation method, proved useful on several occasions in discriminating between an opportunistic infection versus a skin contaminant and in judging efficacy of antimicrobial therapy.

Bacteria↗
PubMed1978

Isolation and rapid identification of yeasts from compromised hosts.

In order to improve the isolation and identification of yeasts in a cancer research hospital, a protocol was developed utilizing an improved blood culture methodology and a four-test schema for rapid yeast identification. The blood culturing technique, based upon centrifugation, has shown a ten-fold increase in isolation of fungi from blood and has provided for: quantitation or organisms, unlimited selection of media and atmospheres for primary culturing, and a 1:200 dilution of microorganisms away from serum antimicrobial factors and antibiotics. The four-test schema, which may be adapted for the identification of any unknown yeast in pure culture, consists of a dye pour plate auxanogram (DPPA), Tween 80-Oxgall-Caffeic acid (TOC), a rapid nitrate-reductase test (swab test) and Urea 'R' Broth. Using this protocol, over 95% of the clinical isolates received were correctly identified within 24 hours and 100% by 48 hours. By using DPPA, a 14 sugar assimilation pattern for each isolate was determined within 12 to 16 hours; and in some cases, as little as 6 hours. Growth on TOC yielded one of the following results: (1) Candida albicans and Candida stellatoidea sequentially produced germ tubes and chlamydospores in 3 hours and 24 hours, respectively; (2) Cryptococcus neoformans produced a brown pigment specific for its identification in 12 hours or less. The swab test gave results on nitrate utilization in less than 15 minutes and urease was detected within 4 hours.

Blood↗
PubMed1978

Physiology of L-asparaginase synthesis in recombinants of Escherichia coli A-1.

A mating between Escherichia coli 4318 (thi leu Las- Hfr) and E. coli A-1 (Met- Las+ F-) resulted in the formation of prototrophic recombinants having L-asparaginase activities at three distinct levels. The physiology of L-asparaginase synthesis in these recombinants is decribed. One class of recombinants produced significantly more L-asparaginase than E. coli A-1. L-Asparaginase synthesis in the recombinants was inhibited by the presence of dissolved oxygen in the medium and was transiently repressed by the presence of glucose in the same manner as that observed in the parental strains. L-Asparaginase activity was increased by the addition of oxalacetate as well as other members of the tricarboxylic acid cycle.

Asparaginase↗
PubMed1978

New centrifugation blood culture device.

A single-tube blood culture device designed for centrifugation in a tabletop centrifuge is described. Reconstruction experiments using 21 different organisms and human donor blood indicate that excellent recovery can be obtained by centrifugation for 30 min at 3,000 X g.

Bacteria↗
PubMed1977

Effect of culture conditions on synthesis of L-asparaginase by Escherichia coli A-1.

The nutritional requirements and culture conditions affecting biosynthesis of L-asparaginase in a mutant of Escherichia coli HAP designated strain A-1 were studied. Asparaginase activity was increased by the addition of L-glutamic acid, L-glutamine, or commercial-grade monosodium glutamate. The rate of enzyme synthesis was dependent on the interaction between the pH of the culture and the amount of oxygen dissolved in the medium. A critical oxygen transfer rate essential for asparaginase formation was identified, and a fermentation procedure is described in which enzyme synthesis is controlled by aeration rate. Enhancement of L-asparaginase activity by monosodium glutamate was inhibited by the presence of glucose, culture pH, chloramphenicol, and oxygen dissolved in the fermentation medium.

Asparaginase↗
PubMed1976

Blood culture technique based on centrifugation: developmental phase.

A quantitative and flexible blood culture system based on centrifugation of lysed blood over a density layer is described. The effect of relative centrifugal force, centrifugation time, and two different density solutions on the recovery of Staphylococcus aureus, Escherichia coli, pseudomonas aeruginosa, and Candida albicans was determined. To demonstrate the versatility of this technique, the reisolation of 23 representative microorganisms from inoculated normal human blood was determined at a fixed centrifugation speed and time. The potential merits of this technique are discussed and compared with those of conventional blood culture methods.

Blood↗
PubMed1976

Blood culture technique based on centrifugation: clinical evaluation.

A total of 1,000 blood samples from patients suspected of having a bacteremia were analyzed concurrently, where possible, by three methods: (i) Trypticase soy broth with sodium polyanethol sulfonate and a CO2 atmosphere: (ii) pour plates with either brain heart infusion agar or Sabouraud dextrose agar; and (iii) centrifugation of the suspected organism in a hypertonic solution. There were 176 positive cultures. The centrifugation technique recovered 73% of the positive cultures. The broth and pour plate techniques recovered 38 and 49%, respectively. The centrifugation technique showed an increased isolation rate for Pseudomonas, fungi, and gram-positive cocci. In general, for each organism the time required for the detection of a positive culture was shortest for the centrifugation technique.

Bacteria↗
PubMed1972

Computerized meiotic mapping in Aspergillus nidulans.

A computer system for the storage and processing of microbial meiotic data has been developed. Based on the language Fortran 4, the program retrieves relevant data and determines the order, map distances, and coefficient of coincidence for any three-gene group. Meiotic data from Aspergillus nidulans were used to test the program. A total of 61 three-gene sequences were processed, and the results were found to be compatible with the published values. The advantages and disadvantages of computer analysis for genetic analysis are discussed.

Aspergillus↗
PubMed1972

Purification and characterization of acid phosphatase V from Aspergillus nidulans.

Acid phosphatase V of Aspergillus nidulans was purified by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzyme demonstrated a charge microheterogeneity on starch and acrylamide gel electrophoresis, but proved to be homogeneous on ultracentrifugation and gel filtration. Phosphatase V was found to be a classic acid orthophosphoric monoester phosphohydrolase, and it cleaved p-nitrophenylphosphate, glucose-6-phosphate, and uridine-5'-monophosphate at maximal rates. It was inhibited by fluoride, borate, and molybdate ions, and demonstrated end-product inhibition by inorganic phosphate. Metallic ions or cofactors were not required for activity. The molecular weight was estimated to be 100,000, the S(20,w) was calculated to be 4.1, and the pH optimum was found to be 6.1.

Acid Phosphatase↗