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Biomedical subjects

D J Brenner

Publications and source records attributed to D J Brenner.

At least 271 records · Page 15Linked to original sources
PubMed1985

Comparison of four hippurate hydrolysis methods for identification of thermophilic Campylobacter spp.

The test for hippurate hydrolysis is critical for separation of Campylobacter jejuni and C. coli strains. Glycine and benzoic acid are formed when hippurate is hydrolyzed by C. jejuni. The test used in most laboratories is one of several variations of the ninhydrin tube test described by Hwang and Ederer (M. Hwang and G. M. Ederer, J. Clin. Microbiol. 1:114-115, 1975) for detection of glycine. We evaluated three modifications of the Hwang and Ederer method and the gas-liquid chromatographic (GLC) method described by Kodaka et al. (H. Kodaka, G. L. Lombard, and V. R. Dowell, Jr., J. Clin. Microbiol. 16:962-964, 1982) for detecting benzoic acid. Campylobacter strains comprised 22 C. jejuni, 11 C. coli, and 8 C. laridis strains. The species identification of each strain was confirmed by DNA relatedness. All strains of C. jejuni were positive and all strains of C. coli and C. laridis were negative by the GLC method for detecting hippurate hydrolysis, whereas three strains of C. jejuni gave negative or variable results in the tube tests. The GLC method is more sensitive than the tube methods for detecting hippurate hydrolysis and should be used on cultures yielding variable or questionable test results.

Bacteriological Techniques↗
PubMed1985

Fatal Legionella maceachernii pneumonia.

Legionella maceachernii, previously isolated only from the environment, was shown to be a cause of fatal pneumonia in an immunocompromised patient.

Bacterial Infections↗
PubMed1985

On the microdosimetric definition of quality factors.

A formulation of the concept of quality factor based on the microdosimetric quantity lineal energy, y, is described. Toward this end, functions--denoted Specific Quality Functions (SQF)--are defined such that (a) they can be determined directly from observation and (b) a number of them can be used toward setting, by consensus, the values of a microdosimetrically-based quality factor. The determination of SQFs is exemplified by correlating data on the yields of dicentric aberrations in human lymphocytes with measured and calculated microdosimetric distributions. The implications of this approach to problems of radiation protection are discussed.

Alpha Particles↗
PubMed1984

Legionella sainthelensi: a new species of Legionella isolated from water near Mt. St. Helens.

Six strains of a new species, Legionella sainthelensi, were isolated from freshwater in areas affected by the volcanic eruptions of Mt. St. Helens in the state of Washington. Strains of L. sainthelensi are culturally and biochemically similar to other legionellae. They grow on buffered charcoal yeast agar but not on media that lack cysteine. They are gram-negative, nonsporeforming, motile rods that are positive in reactions for catalase, oxidase, gelatin liquefaction, and beta-lactamase. They are negative in reactions for urease, hydrolysis of hippurate, reduction of nitrates, fermentation of glucose, and blue-white autofluorescence. Their cell wall fatty acid composition is qualitatively similar to those of other legionellae, with 50 to 62% branched-chain fatty acids. They contain the isobranched-chain 14- and 16-carbon acids and anteisobranched-chain 15- and 17-carbon acids and relatively large amounts of straight-chain 16-carbon acid. All strains of L. sainthelensi contain approximately equal amounts of ubiquinones Q9, Q10, Q11, and Q12, a pattern similar to those of Legionella bozemanii, Legionella dumoffi, and Legionella longbeachae. Serological cross-reactions were observed between L. sainthelensi, both serogroups of L. longbeachae, and Legionella oakridgensis. Three strains of L. sainthelensi were greater than 90% related by DNA hybridization. The type strain of L. sainthelensi, Mt. St. Helens 4, was 36% related to the type strain of L. longbeachae and 3 to 14% related to the other nine described Legionella species.

Disasters↗
PubMed1984

Legionella bozemanii serogroup 2: a new etiological agent.

A newly discovered bacterium, Toronto 3, isolated from a lung aspirate of a patient with pneumonia, has been characterized. The isolate was identified as Legionella bozemanii by chemical data from cellular fatty acid and ubiquinone analyses and by DNA relatedness studies. The isolate, however, differs phenotypically from L. bozemanii by its colonial characteristics and strong interspecies serological cross-reactions, which are unique among clinical isolates of legionellae. The name L. bozemanni serogroup 2 is proposed. The reference strain is Toronto 3. The clinical illness caused by L. bozemanii serogroup 2 was not distinguishable from other Legionella infections. L. bozemanii is the third Legionella species with more than one serogroup. Rapid laboratory diagnosis of this strain by direct fluorescent antibody test may be complicated in the absence of culture isolation.

DNA, Bacterial↗
PubMed1984

Moellerella wisconsensis, a new genus and species of Enterobacteriaceae found in human stool specimens.

The name Moellerella wisconsensis is proposed for a group of the family Enterobacteriaceae previously called enteric group 46. The species name, wisconsensis, was coined because six of the nine strains were isolated in Wisconsin. M. wisconsensis strains were negative for indole production, Voges-Proskauer, H2S production, urea, phenylalanine deaminase, lysine and ornithine decarboxylases, arginine dihydrolase, gas production from D-glucose, acid production from trehalose, and motility; the strains were positive for methyl red, citrate (Simmons), and acid production from lactose and raffinose and resistant to colistin. DNAs from five strains of M. wisconsensis were highly related (80 to 93% in reactions assayed on hydroxyapatite at 60 degrees C and 78 to 97% at 75 degrees C) to 32P-labeled DNA of the proposed type strain (CDC 2896-78, ATCC 35017). Labeled DNA from this type strain was only 2 to 32% related (at 60 degrees C) to DNA from 49 strains of named and unnamed species of Enterobacteriaceae. Eight of nine M. wisconsensis strains were isolated from human stool samples. Clinical information on one strain was available, and it was found to be associated with a case of diarrhea. On MacConkey agar, colonies of M. wisconsensis were bright red with precipitated bile around them and thus were indistinguishable from Escherichia coli colonies. Future studies should focus on the isolation of this new organism and its relationship to human disease.

Adult↗
PubMed1984

Vibrio fluvialis and Vibrio furnissii isolated from a stool sample of one patient.

Vibrio fluvialis and Vibrio furnissii have been associated with diarrhea but have rarely been isolated in the United States. We received strains of V. fluvialis and V. furnissii that were isolated from the stool of a 1-month-old baby. A description of these two strains and the case history of the patient are given in this report.

Anti-Bacterial Agents↗
PubMed1984

DNA relatedness among strains of Campylobacter jejuni and Campylobacter coli with divergent serogroup and hippurate reactions.

Eleven strains of Campylobacter from earlier fluorescent-antibody studies were examined by DNA hybridization to determine their species. Three of the strains hydrolyzed sodium hippurate, and eight did not. Four of the hippurate-negative strains were in Campylobacter jejuni serogroups, and the remaining strains were in both C. jejuni and Campylobacter coli serogroups. DNA relatedness to type strains of C. jejuni and C. coli indicated that all three of the hippurate-positive strains and two of the hippurate-negative strains were C. jejuni. The six remaining hippurate-negative strains were C. coli. Two of the hippurate-negative strains in C. jejuni serogroups were C. jejuni, and two were C. coli. Three of the strains in serogroups of both species were C. jejuni, and four were C. coli. These studies confirm that a few strains of C. jejuni are hippurate negative and show that identical or highly related antigens are found in C. coli and C. jejuni.

Campylobacter↗
PubMed1984

DNA characterization of the spirochete that causes Lyme disease.

Lyme disease, a tick-borne disease long recognized in Europe but only recently recognized in the United States, was shown in 1982-1983 to be caused by a spirochete, the Lyme disease spirochete. Whether one or more species of the spirochete exists is unknown, as is its taxonomic status. To answer these questions, we determined (i) the DNA base (guanidine-plus-cytosine) content for five strains; (ii) the DNA relatedness of 10 strains from Europe or the United States (isolated from ticks, humans, and a mouse) by DNA hybridization (hydroxyapatite assay at 50 and 65 degrees C); and (iii) the DNA relatedness to other pathogenic spirochetes. The guanine-plus-cytosine content of the Lyme disease spirochete strains was 27.5 to 29.0 mol%, most similar to those of Borrelia hermsii (30.6 mol%) and Treponema hyodysenteriae (25.6 mol%) among the other spirochetes tested. DNA hybridization studies with 32P-labeled DNA from Lyme disease spirochete strain TLO-005, a human blood isolate, revealed divergence (unpaired bases) within related nucleotide sequences of only 0.0 to 1.0% for all nine Lyme disease spirochete strains tested for relatedness to TLO-005. Relatedness values of seven strains to TLO-005 were 58 to 98% (mean, 71%) in 50 degrees C reactions and 50 to 93% (mean, 69%) in 65 degrees C reactions. Two other strains, from which very low yields of DNA were obtained, showed less relatedness (36 to 50 degrees C, 38 to 47% at 65 degrees C). These were nonetheless considered to belong to the same species because of the low amount of divergence in the sequences related to TLO-005 and the absence of decreased relatedness in reactions done at 65 degrees Celsius compared with those done at 50 degrees Celsius. DNA from strain TLO-005 showed relatedness of 1% to DNAs of two leptospires and 16% relatedness to DNA from T. hyodysenteriae. B. hermsii DNA was 30 to 40% related to three Lyme disease spirochete strains in 50 degrees Celsius reactions. Divergence in these reactions was 16.5 to 18.5%, and relatedness in 65 degree Celsius reactions was 8 to 10%. On the bases of phenotypic similarity, guanine-plus-cytosine content, and DNA relatedness to B. hermsii, we conclude the Lyme disease spirochete is single previously undescribed species which belongs in the genus Borrelia.

Animals↗
PubMed1984

Legionella pneumophila serogroup 9: a cause of human pneumonia.

A new serogroup of Legionella pneumophila was isolated from bronchoscopic washings and an open-lung biopsy specimen of a patient from California with pneumonia. A serologically identical isolate was obtained from tap water of a hospital ward in the Netherlands, and a fatal case of pneumonia in a patient from Virginia was shown retrospectively to have been caused by this new organism. The type strain of what is now serogroup 9 of L. pneumophila is IN-23-G1-C2 (American Type Culture Collection no. 35289). Disease caused by L. pneumophila serogroup 9 is not apparently different from that caused by other L. pneumophila serogroups.

Agglutination Tests↗
PubMed1984

The application of track calculations to radiobiology. II. Calculations of microdosimetric quantities.

In this second paper of a series, Monte Carlo-simulated proton tracks in water vapor are analyzed to yield a range of quantities that are of radiobiological interest. These include proximity functions of energy deposition, lineal energy distributions in micrometer and nanometer site sizes, and radial energy distributions. Many of these quantities cannot be measured with current experimental techniques. Some results are compared with those from analytic calculations. Also the effect on such quantities of the uncertainties in cross-sectional data used in the original Monte Carlo calculations is assessed, as is the effect of including nonionizing energy-loss events for analysis in the calculation.

Energy Transfer↗
PubMed1984

Modification of the theory of dual radiation action for attenuated fields. I. Basic formalism.

A modification of the Theory of Dual Radiation Action is described to take into account the effects of an attenuated beam of radiation across the sensitive site of the cell. It is shown that, unlike the case of uniform radiation, the coefficient of the dose-squared (intertrack) term is not constant, but varies in a manner dependent on the attenuation coefficient of the radiation and the geometry of the site.

Cell Survival↗
PubMed1984

Modification of the theory of dual radiation action for attenuated fields. II. Application to the analysis of soft X-ray results.

A formalism developed in the first paper in this series, based on the generalized Theory of Dual Radiation Action, is applied to survival data for cells exposed to soft X rays. It is shown that, in contrast to previous published analyses, this formalism--modified to account for the attenuation of dose across the sensitive matrix of the cell--is fully consistent with the experimental results. The reasons for previous disagreements are discussed.

Cell Survival↗
PubMed1984

The application of track calculations to radiobiology. III. Analysis of the molecular beam experiment results.

Survival data from the molecular beam experiment are used to obtain an estimate of the function gamma (chi), describing the probability for two energy transfers a distance chi apart to produce a lesion. A comparison is made between the functions gamma (chi) obtained using proximity functions calculated with Monte Carlo-generated tracks and with simplifying assumptions (the LET approximation). The results differ substantially, which shows that the results are very sensitive to the degree of detail used in characterizing the physics of the irradiating field.

Cell Survival↗
PubMed1984

On the stochastic treatment of fast chemical reactions.

A Monte Carlo code was developed to stimulate stochastically the fast reactions of radiolysis products in water. The results of these calculations show that treatments based on deterministic kinetic rate equations do not reproduce correctly the evolution in time of the number of species. Ad hoc initial distributions of species in spurs, of the type used in deterministic approaches, are compared with more realistic distributions obtained from Monte Carlo-generated particle tracks. The effects of using either type of distribution, stochastically or deterministically, are discussed.

Electrons↗
PubMed1983

Estimation of a single property of low LET radiations which correlates with biological effectiveness.

The biological effectiveness of ionising radiation is believed to be related to the initial structure of the radiation tracks. In this paper, an attempt is made to identify a single physical property of the radiation field that correlates with relative biological effectiveness. This property has been sought in terms of a minimum amount of energy deposition in a certain volume. In order to quantify this approach detailed Monte Carlo track structure simulations have been made of x-rays of widely differing energies and the results have been compared with previously reported experiments of cell killing by these radiations. In terms of the above threshold energy concept, we have thus identified a putative critical property of radiations of low ionisation density such as x-rays, namely the rare occurrence of energy deposition of greater than or equal to 100 eV in a volume of about 3 nm diameter.

Cell Survival↗