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C S Dow

Publications and source records attributed to C S Dow.

12 recordsLinked to original sources
PubMed2005

Data reduction in headspace analysis of blood and urine samples for robust bacterial identification.

This paper demonstrates the application of chemical headspace analysis to the problem of classifying the presence of bacteria in biomedical samples by using computational tools. Blood and urine samples of disparate forms were analysed using a Cyrano Sciences C320 electronic nose together with an Agilent 4440 Chemosensor. The high dimensional data sets resulting from these devices present computational problems for parameter estimation of discriminant models. A variety of data reduction and pattern recognition techniques were employed in an attempt to optimise the classification process. A 100% successful classification rate for the blood data from the Agilent 4440 was achieved by combining a Sammon mapping with a radial basis function neural network. In comparison a successful classification rate of 80% was achieved for the urine data from the C320 which were analysed using a novel nonlinear time series model.

Bacteremia↗
PubMed1999

A new automated system for urine analysis: a simple, cost-effective and reliable method for distinguishing between glomerular and nonglomerular sources of haematuria.

OBJECTIVE: To determine the ability, reliability and accuracy of a new automated system of urine analysis in differentiating glomerular from nonglomerular bleeding in the initial investigation of haematuria, and compare its efficacy with conventional phase-contrast microscopy (PCM). PATIENTS AND METHODS: One hundred and six urine samples from patients in whom the final diagnosis was available were analysed using electrical flow impedance to detect, enumerate and size red blood cells in a conductive fluid (the cellfacts analyser, Microbial Systems Ltd, Coventry, UK). All the samples were also tested using a dipstick method and PCM was carried out for comparison on 45 of the 106 urine specimens. The results of cellfacts analysis were correlated with the final diagnoses to assess sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of this method; the costs were also analysed. RESULTS: Sixty-nine urine samples tested positive for blood on dipstick urine analysis and all these were confirmed to have red blood cells on cellfacts analysis. The remaining 37 samples were negative for blood on dipstick testing and cellfacts analysis, although seven patients had been referred with previously detected microscopic haematuria, none of whom were found to have any detectable pathology in the urinary tract on clinical examination and investigations. The remaining 30 patients were diagnosed to have urological or nephrological conditions with no haematuria. In the positive group, 20 (29%) patients were from the glomerular group, with a mean (range) red blood cell size of 4.25 (4-5.1) micrometer, and 49 (71%) from the nonglomerular group, with red blood cells of 5.47 (4.67-5.70) micrometer. These ranges overlapped at 4.67-5.1 micrometer at the decision threshold of 4.75 micrometer, the distribution of dysmorphic and eumorphic red blood cells for the glomerular group was 18 (90%) and two (10%), respectively, and for the nonglomerular group was 2 (4%) and 47 (96%), respectively. The sensitivity, specificity, PPV and NPV were 90%, 96%, 90% and 96%, respectively. Consumable and labour costs were very low. CONCLUSIONS: Cellfacts analysis is a simple, rapid, objective and cost-effective method for differentiating glomerular from nonglomerular urinary red blood cells, especially when few such cells are present.

Adult↗
PubMed1987

Growth of bacteria with dimorphic vegetative cell cycles.

A mathematical model of the growth of bacteria with dimorphic cell cycles is described. In these bacteria motile swarmer cells differentiate to stalked reproductive cells and the proportions of these cell types change in a characteristic fashion during growth. The selection of parameters to fit the model to experimental data can result in the elucidation of the factors controlling the differentiation of swarmer cells.

Bacteria↗
PubMed1987

DNA:DNA hybridization studies on the pink-pigmented facultative methylotrophs.

The genomic relatedness among 36 strains of pink-pigmented facultatively methylotrophic bacteria (PPFMs) was estimated by determination of DNA base composition and by DNA:DNA hybridization studies. A reproducible hybridization system was developed for the rapid analysis of multiple DNA samples. Results indicated that the PPFMs comprise four major and several minor homology groups, and that they should remain grouped in a single genus, Methylobacterium.

Bacteria↗
PubMed1986

Purification and partial characterization of DNA-dependent RNA polymerase from Rhodomicrobium vannielii.

DNA-dependent RNA polymerase has been isolated from Rhodomicrobium vannielii. Like those from other eubacteria, the enzyme contained four subunits: beta and beta prime (Mr 155,000), alpha (Mr 38,000), and sigma (Mr 98,000). Analysis by isoelectric focussing showed that both alpha and sigma had several forms with different isoelectric pH values. The enzyme was sensitive to rifampicin (5 ng rifampicin ml-1 gave 50% inhibition) and capable of specific promoter selection with DNA from R. vannielii, calf thymus and phage T7D111.

Chromatography, Gel↗
PubMed1984

Microbial differentiation: the role of cellular asymmetry.

The inherent cellular asymmetry in the cell cycles of the prosthecate budding bacteria, which involves the production of structurally and functionally distinct cell types, stems from the obligate polar growth patterns of these microbes. The examination of a range of bacteria, however, suggests that such asymmetry may be more widespread than hitherto recognized.

Bacteria↗
PubMed1981

Rapid screening for bacteriuria using a particle counter, pulse-height analyser, and computer.

A system for the rapid screening of urines for the presence of bacteriuria has been devised using a Coulter Counter Model ZBI linked to a multichannel pulse-height analyser (Coulter "Channelyser") with computer analysis of the output. In a series of 215 urines containing growth of a single pathogen of more than 100 x 10(6)/l (greater than 100 000/ml) satisfactory level of sensitivity (99.1%) was obtained using only two different amplification settings by means of a brief treatment (5-10 seconds) of the undiluted specimen with low intensity ultrasound; 85-90% of mixed growths of 10 x 10(6)/l (greater than 10 000/ml) were detected. Sonication did not improve the results in this group. Specimens showing abnormal cyturia of more than 10 x 10(6)/l (greater than 10 000/ml) but no growth on culture were positive in 33% of cases without the use of ultrasound but in 72% after sonication.

Bacteriological Techniques↗
PubMed1979

Particle size distribution analysis for the rapid detection of microbial infection of urine.

The accuracy and practicality of particle size distribution analysis for rapid screening of urine specimens are assessed. Six hundred urines were subjected simultaneously to routine bacteriological examinations and particle size distribution analysis using a Coulter Counter (ZBI) linked to a C1000 Channelyzer. There was complete agreement in the results of 593 (98.8%) specimens. Characteristic profiles of various bacterial species in infected specimens were consistently obtained. This system can easily be linked to any existing computer reporting in a district hospital laboratory, and the results of negative specimens (70--80%) can be obtained within 5--10 minutes.

Bacteriological Techniques↗