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Biomedical subjects

T N Bryant

Publications and source records attributed to T N Bryant.

At least 19 recordsLinked to original sources

Speech recognition and the clinical microbiology laboratory.

Keyboard entry of large amounts of diagnostic data is a laborious task. Any transcription errors that occur may pass undetected by 'non-technical staff' employed to input these data. The object of this project was to design a system, based on a Marconi 'Macrospeak' Speech Recogniser, for 'on line' laboratory entry of data generated from the microbiological examination of specimens of urine. Six parameters considered important to the success of the system were assessed: accuracy, speech recognition, reproducibility, speed, user friendliness, and cost effectiveness. The system performed well under the test conditions examined. 'On line' hands free entry of diagnostic data, using speech recognition, may be a practical alternative to more conventional means of data entry.

Clinical Laboratory Information Systems

Software for the development and evaluation of probabilistic identification matrices.

A number of programs are described for the development and evaluation of probabilistic identification matrices for use with computer-assisted identification. The program BEST reads an initial matrix of per cent probabilities for all the binary characters examined during a cluster analysis and determines the most useful set of tests for distinguishing taxa in the matrix. Program RESORT creates from the initial matrix an identification matrix in which the order of the tests may be different or the number of tests reduced. A printed version of a matrix can be produced by MATPRINT, which creates tables giving the per cent probability of a positive test result and the test results presented as '-', 'v' and '+' depending on a user-specified threshold. Program IDSC evaluates an identification matrix by calculating the best identification score for each taxon in the matrix using the expected result for each test. The programs were written in FORTRAN 77 and can be run on any micro-computer using the PC/MS-DOS operating system.

Algorithms

Investigation of an expert systems approach to bacterial identification.

An investigation was carried out to assess the feasibility of using an expert systems approach to assist in the identification of unknown isolates of bacteria. A system was developed using Lisp which utilized the knowledge stored in standard bacteriological texts. A comparison of the expert systems approach and the probabilistic approach based on Bayes Theorem was made together with the advantages and disadvantages of each approach.

Algorithms

The incidence of virulence factors in mesophilic Aeromonas species isolated from farm animals and their environment.

Sixty-one isolates of Aeromonas spp. from the faeces of pigs, cows and a variety of associated environmental sources were examined for the characteristics that are reputed to have roles in pathogenicity. Most isolates of Aeromonas hydrophila were cytotoxic (96.4%) and were capable of producing cell elongation factor (75%) and haemagglutinins (67.9%). In contrast few of the Aeromonas caviae isolates produced these three markers (13.6%, 27.3% and 36.4% respectively). In general, Aeromonas sobria occupied an intermediate position (36.4%, 27.3% and 54.5%), but they did produce the highest mean invasion index for HEp-2 cells. Statistical analysis revealed significant associations between the carriage of these factors and it was clear that many isolates of aeromonads from water and animals possessed the full battery of putative virulence factors.

Aeromonas

Continuous versus intermittent epidural analgesia. A randomised trial to observe obstetric outcome.

A randomised study of 381 women was carried out to compare the obstetric outcome after epidural analgesia maintained by an intermittent top-up regimen or with a continuous infusion. The two groups were well matched with respect to age, parity, mode of onset of labour and indication for epidural. Maintenance of epidural analgesia by continuous infusion resulted in a significantly decreased need for top-up doses. A reduction in the incidence of hypotension, cardiotocographic evidence of intrapartum fetal hypoxia and Caesarean section was associated with this. It is concluded that the maintenance of epidural analgesia by continuous infusion is a safe and reliable method and may be more advantageous and less labour intensive than the traditional intermittent regimen.

Analgesia, Epidural

Taxonomic investigation of Legionella pneumophila using monoclonal antibodies.

A panel of 19 monoclonal antibodies was used to produce patterns of immunofluorescent staining of 468 isolates of Legionella pneumophila. Twelve monoclonal antibodies were selected that divided L. pneumophila into 17 phenons which, in the majority of cases, conform to serogroup divisions. These phenons are more easily defined than the present serogroups, and isolates can be placed in them with little ambiguity. The standardized set of monoclonal antibodies was also used to define the subgroups of serogroup 1.

Antibodies, Monoclonal

Neonatal renal function assessment.

Urine samples from neonates admitted to a special care baby unit were analysed to establish ranges for urinary retinol binding protein, albumin, and total protein concentrations in healthy term and preterm infants and to investigate changes seen in disease states. Urinary excretion of retinol binding protein was greater in preterm infants and was increased in sick infants. This was greater than would be predicted from changes in creatinine excretion with gestational or postconceptional age. Urinary retinol binding protein appeared more sensitive to illness than did urinary albumin or total protein.

Albuminuria

Programs for evaluating and characterising bacterial taxonomic data.

Three programs are described for evaluating and characterising data collected during numerical taxonomic studies of bacteria. The program VARIANCE compares replicate cultures and evaluates the reproducibility of each character. Also it identifies those characters that should be excluded from subsequent taxonomic analysis because of their poor reproducibility. GPROPS summarises the properties of clusters of strains that have been defined from a cluster analysis, it can produce a probabilistic identification matrix and compares each strain within a cluster with the Hypothetical Mean Organism (HMO) of that cluster. OVCLUST is an implementation of the program described by Sneath (1979) which calculates overlap statistics between major clusters. These programs are designed to complement the CLUSTAN package (Wishart, 1982) which is often used for cluster analysis of bacterial taxonomic data. The programs were written in FORTRAN 77 and implemented on an IBM PC using MS-DOS.

Algorithms

Indirect monitoring and analysis of truncal stress over extended time periods.

Low back pain is a common ailment encountered in clinical practice, yet there has hitherto been no completely satisfactory method for the measurement of truncal stress, which is a major factor in low back pain. Truncal stress has been difficult to record during the course of a working day because subjects were constrained by trailing cables attached to the monitoring equipment. We have used a pressure sensitive transmitter (radio pill) to record intra-abdominal pressure, which has been shown previously to be an indirect measure of truncal stress. The system makes possible multichannel recordings on magnetic tape throughout the working day by using a portable, battery powered recorder strapped to the subject's waist. A novel ferrite rod contributes materially to minimizing artefacts due to signal loss. The recorded data are replayed, at 60 times real time, into a microcomputer programmed to analyse this data.

Abdomen

A numerical taxonomic study of anaerobic gram-negative bacilli classified as Bacteroides ureolyticus isolated from patients with non-gonococcal urethritis.

A numerical taxonomic study of 64 strains of anaerobic Gram-negative bacilli isolated from men with non-gonococcal urethritis, two unclassified laboratory strains of 'corroding bacilli', and 12 other strains of anaerobic Gram-negative bacilli, including nine received as anaerobic curved rods and three as 'Bacteroides corrodens' (B. ureolyticus), isolated from women with bacterial vaginosis, was undertaken. Seventeen reference anaerobic strains belonging to the genera Bacteroides, Fusobacterium, Mobiluncus, Mitsuokella and Wolinella were included. Morphological, biochemical and physiological characteristics were examined in 103 tests. The resemblance between the 95 strains was calculated using the SSM, SJ and DP coefficients for cluster analyses based on the UPGMA method. All three approaches gave similar groupings, and the estimated average probability of test error was 2.46%. The strains fell into 10 phenons. The unclassified strains from men and three from women with lower genital-tract infections, and the laboratory strains of 'corroding bacilli' clustered in one phenon with the reference strains of B. ureolyticus, indicating that they correspond to B. ureolyticus. The other unclassified strains of anaerobic curved rods clustered as a distinct phenon. They correspond to species of the newly described genus Mobiluncus. The taxonomic data and the compilation of diagnostic tables serve as a useful guide for the laboratory identification of clinical isolates regarded as B. ureolyticus.

Bacteroides

Numerical classification of species of Vibrio and related genera.

Data from 1091 strains of the family Vibrionaceae collected in five different studies have been merged into a single data matrix and analysed in a taxonomic study. A set of 142 characters was selected to compare these data. Seventy-nine characters were common to all studies, but data for the other 63 characters were incomplete. Cultures of 90 strains, examined in more than one of the original studies, were used to estimate test error and inter-study variability. The data from these replicate strains also allowed the problem of merging data from different studies to be assessed. Taxonomic resemblance was estimated on the basis of 111 characters using the SSM coefficient and UPGMA clustering. A taxonomic analysis based on 999 strains, which included most of the major species of the family Vibrionaceae, gave 59 clusters and 44 unclustered strains. A table of properties of these phenons was produced. The results showed that data obtained from studies carried out at different times and in different locations, but using standard techniques, could be combined and used to provide useful taxonomic information.

Software

A probability matrix for the identification of species of Vibrio and related genera.

A matrix for the probabilistic identification of species of Vibrio and related genera has been constructed using the data from 1091 strains collected throughout the world and classified. Thirty-eight phenons are included in the matrix, 31 of these represent previously identified species or biovars and seven represent phenons which could not be identified and may represent new species. The identification matrix incorporates 81 characters although a subset of 30 tests can be used to distinguish the 38 phenons from each other. The additional 51 tests were included to assist the identification of some strains for which the initial 30 tests were inadequate. No significant cluster overlap was found at the 5% level and the identification score for the Hypothetical Median Organism of each cluster exceeded 0.9999 in all cases.

Probability

Vibrio cincinnatiensis sp. nov., a new human pathogen.

A halophilic gram-negative rod was isolated from blood and cerebrospinal fluid collected from a 70-year-old male having no known contact with seafood or salt water. Positive biochemical tests included oxidase, sensitivity to 0/129, O-nitrophenyl-beta-D-galactopyranoside, lysine decarboxylase and fermentation of glucose, salicin, n-inositol, sucrose, L-mannose, L-arabinose, and arbutin. Negative tests included indole, ornithine decarboxylase, arginine dihydrolase fermentation of lactose, and production of gelatinase and urease. The DNA base composition was 45.0 mol% guanine plus cytosine. Numerical taxonomy indicated 70% similarity with known reference Vibrio sp. strains. The 5S rRNA sequence for this strain has been determined: 5'-U G C C U G G C G A C C A U A G C G U U U U G G A C C C A C C U G A U U C C A U G C C G A A C U C A G U A G U G A A A C G A A A C A G C G U C G A U G G U A G U G U G G G G U C U C C C C A U G U G A G A G U A G A A C A U C G C C A G G C A U-3'. Based on the phenetic, molecular genetic, and nucleic acid sequencing data, it is concluded that Vibrio cincinnatiensis represents a new species of the genus Vibrio sensu strictu (as defined by 5S rRNA sequencing results). On a basis of 5S rRNA comparative sequence analysis, the organism appears to share a recent common ancestor with V. gazogenes (98% homology) and close ancestry with V. mimicus, V. fluvialis, and V. metschnikovii.

Aged

Microcomputer assisted identification of Bacillus species.

A microcomputer based system for the identification of unknown isolates of Bacillus species is described. The identification matrix includes 78 test probabilities for 38 recognised species and other groups in the genus Bacillus and it is based on the work of Logan and Berkeley (1984). Morphological characters together with the results of tests using API 20E and API 50CHB, read after 24 and 48 h incubation, are used to obtain a probabilistic identification of an unknown aerobic endospore forming rod. Any differences between the observed and expected results for any identified organism are listed. Identification can be attempted on the basis of a limited set of test results, although this is rarely if ever done with this largely API based system, and if the unknown cannot be successfully identified then a set of additional tests can be selected which should permit identification. The computer system can store and recall test results entered for any isolate. This feature allows the accumulation of data on isolates which could be used to update the identification matrix in future taxonomic studies.

Bacillus

DNA:rRNA hybridization studies of Chromobacterium fluviatile.

Hybrids were prepared between 14C-labelled rRNA from each of nine species of Gram-negative bacteria and the DNA of Chromobacterium fluviatile. Two parameters were determined for each hybrid - the T m(e), which is the temperature at which 50% of the hybrid was denatured, and the percentage of rRNA bound under defined stringent conditions. The former gives a measure of the stability of the duplex once formed and the latter probability reflects the amount of the genome involved in the coding of rRNA. These parameters were used as a measure of the relatedness of C. fluviatile to each of the other nine species. The results suggest that C. fluviatile is more closely related to C. violaceum than to any other species tested. The taxonomic relationship of C. fluviatile to other Gram-negative bacteria was assessed by incorporating the results into a database already published by De Ley et al. (1978), and the use of principal components analysis was explored as an alternative way of presenting such data. This analysis confirmed the isolated position of C. fluviatile but, until further isolates are studied, it seems best to retain the species in the genus Chromobacterium.

Chromobacterium

An investigation of the immune response of patients suffering from anorexia nervosa.

Patients suffering from anorexia nervosa rarely appear to develop the common cold or influenza. This study examines the immunological response of fifteen female anorexia nervosa patients of both the vomiting and carbohydrate-abstaining type and compares them with a control population matched for age and occupation. Both anorectics and control populations received the admune influenza vaccine. Initially both groups had similar haemagglutination inhibition titres against the three different viral antigens: A/HK; A/PC; A/Eng. However, the anorectics showed over a 2-month period a higher titre of antibody especially to the Hong Kong virus: this was sigignificant. Cellular immune responses were measured using a tuberculin and a macrophage inhibition test, no significant difference between the two groups was obderved. These results which support the clinical findings are discussed.

Adolescent