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C J Thomas

Publications and source records attributed to C J Thomas.

At least 109 records · Page 6Linked to original sources
PubMed1989

Molecular cloning and expression in Escherichia coli K-12 of the O101 rfb region from E. coli B41 (O101:K99/F41) and the genetic relationship to other O101 rfb loci.

The gene cluster (rfb region) which determines the synthesis of O101 lipopolysaccharide (LPS) O-antigen was cloned from the Escherichia coli O101:K99:F41 reference strain B41 to give plasmid pPM1301. The smallest subclones represented by pPM1305 and pPM1330 expressed O-antigen in E. coli K-12 similar to (but not identical to) B41, as judged by immunogold electron microscopy and silver staining of LPS separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). At least six proteins were detected by minicell analysis of proteins encoded by pPM1305, which suggests that O-antigen synthesis is genetically complex. Restriction and deletion analysis demonstrated that a minimum of 8.9 kb and a maximum of 11.8 kb are required for O101 O-antigen biosynthesis in E. coli K-12. Examination of LPS banding patterns of other O101 isolates by SDS-PAGE suggested heterogeneity of LPS structure. Southern DNA hybridization analysis using radiolabelled subclones of pPM1305 demonstrated that there was close relationship among the O101 ETEC isolates.

Antigens, Bacterial↗
PubMed1989

Characterization and molecular cloning of the PCF8775 CS5 antigen from an enterotoxigenic Escherichia coli 0115:H40 isolated in Central Australia.

The genes determining the biosynthesis of the colonization factor CS5 have been cloned from Escherichia coli 0115:H40:PCF8775 isolated during an outbreak of diarrhoea among aboriginal children in Central Australia. Electron microscopy has shown purified CS5 to be of semi-rigid fimbrial type. NH2-terminal analysis has shown the CS5 determinant to be distinct from other fimbriae, although there is some conservation of certain residues. Expression in minicells of the cloned fimbrial genes encoded on pPM1312 has shown that proteins of 70 and 46.5 kD which co-purity with the 23 kD major fimbrial subunit protein are also co-expressed along with proteins of 45, 31, 17 and 14 kD. The major CS5 subunit is synthesized in precursor form (approximately 26 kD). A synthetic oligonucleotide to the NH2-terminal amino acid coding sequence of the purified protein has been used in Southern hybridization analyses to define the region on pPM1312 encoding the structural gene for the major pilin subunit.

Amino Acid Sequence↗
PubMed1988

Microbial spoilage of pre-cooked potato-topped pies.

The ecological succession of bacteria which developed in pre-cooked potato-topped pies stored at two different temperatures was examined. Bacillus, Streptococcus and Staphylococcus-Micrococcus spp. were the predominant organisms isolated from freshly prepared pies and those stored at 4 degrees and 37 degrees C. None of these groups of bacteria caused significant biodeterioration of pies held at 4 degrees C, but all groups grew well in pies stored at 37 degrees C and achieved counts of ca 10(8)/g of sample. Bacillus spp. were the first group to grow, followed by Streptococcus and Staphylococcus-Micrococcus spp. Growth which occurred at 37 degrees C did so at the expense of glucose, lactate accumulated and the pH of pie components decreased. Amylase activity detected in all pie components during storage was associated with the growth of Bacillus spp. and probably supplemented glucose already present in pies, by hydrolytic cleavage of potato, flour or binder starches. Spoilage caused by growth and activity of the bacteria isolated was not associated with visual signs of biodeterioration, nor production of 'off' odour usually associated with spoilage of meats. These results suggest that pre-cooked potato-topped pies held at inappropriate temperatures represent a potential public health risk.

Bacillus cereus↗
PubMed1988

Mast cells, elastic fibres and the lamina propria in the hard palate of the rat.

The hard palate tissue of four adult Sprague-Dawley rats was serially sectioned para-sagitally and coronally. Stains for collagen, elastic fibres, non-sulphated and sulphated GAG were used. The collagen fibre component of the lamina propria revealed a well ordered structure which in the ante-molar rugae (AMR) split to enclose a core, but in the inter-molar rugae (IMR) passed under the core. Elastic fibres were liberally distributed in the cores of the AMR, running mainly antero-posteriorly but much sparser in the IMR. Mast cells and GAG were identified by means of the alcian blue pH 2.5 stain and after mapping them through a microscope tracing tube and quantifying the distribution in AMR no 2, three zones of distribution were observed. The core was the least populated zone and a possible connection with the GAG content is suggested. The fibre and GAG constituents of the AMR suggested that they are structural elements aimed at resisting the demands of function.

Animals↗
PubMed1987

An improved statistical method for the racial classification of man by means of palatal rugae.

A classification of human ruga pattern disclosed interracial differences between six population groups. The conventional statistical procedures of linear and quadratic discriminant function and nearest neighbour-point-method delivered overall correct classification figures of 49.2, 45.3 and 29.1 per cent respectively. The jackknife-classification matrix for the kernel-function method delivered an overall percentage correctly classified of 61.1 per cent with an individual group figure range correctly classified of 37-100 per cent. Although computationally elaborate, this technique has led to new insights into the data compared with parametric methods.

Humans↗
PubMed1987

A note on adhesion of bacteria to chicken muscle connective tissue.

Laboratory cultures of bacteria were tested for the ability to attach to collagen fibres of intact chicken muscle connective tissue. All salmonellas, fimbriate strains of Escherichia coli and a strain of Campylobacter coli were able to attach to tissue only when suspended in distilled water. Prior immersion of tissue in sterile water for 20 min or extended immersion in these bacterial suspensions was a prerequisite for adhesion. Attachment could be prevented by the addition of physiological levels of sodium chloride to the attachment medium. Furthermore, attached bacteria could be removed by rinsing tissues in saline media.

Animals↗
PubMed1987

Elastic fibre and hyaluronic acid in the core of human palatal rugae.

The core within the palatal rugae of humans contains elements which are believed to contribute to the maintenance of its shape. A cross-sectional study was represented by 23 specimens of human palatal mucosa aged 3 months to 80 years and stained for sulphated and non-sulphated glycosaminoglycans (GAG), elastic tissue and collagen. Statistical correlations between core margin definition and age and elastic content were significant (p less than 0.005 and p less than 0.025). It was concluded that the main structural element of a ruga is not elastic tissue or collagen but GAG which by its hydrophilic nature causes the tissue to swell and contributes to the maintenance of the shape of a ruga throughout life.

Adolescent↗
PubMed1986

The Carabelli trait in the mixed deciduous and permanent dentitions of five South African populations.

The Carabelli trait in South African negroids, caucasoids, Coloured (Peninsula and Namaqualand) and Indians, classified according to Alvesalo, Nuutila and Portin (1975; Acta odont. scand. 33, 191-197) showed generally peak frequency of expression for dm2 falling into class 3 and for M1 into class 4, that dm2 displays more negative expression (class 2 and 3) and M1 more positive expression (class 4 and 5) and that overall expression in dm2 is higher than in M1. The Indian group was an exception with peak frequencies in class 2 for dm2 and class 1 (right) and class 2 (left) for M1. There was no sex dimorphism and there was a tendency for concordance of expression between sides but not within sides.

Child↗
PubMed1986

The angle of divergence in the palatal ruga pattern.

One of the variables in a classification of the palatal ruga pattern displayed an unusual bimodal distribution which occurred in 6 population groups. The two sub-groups involved were defined by means of a maximum likelihood estimation procedure, a stepwise discriminant analysis and a jackknife classification procedure. The variables which supported the bimodality were mostly concerned with palatal dimensions and the classifications were all above 50% with the Bushman groups classifying better than the others at 77.8% (left) and 70.8% (right).

Africa, Southern↗
PubMed1986

The palatal ruga pattern in possible paternity determination.

The use of a genetic marker in paternity determination has been successful with the ABO blood group system but unsuccessful in dermatoglyphics and palatal rugae because the genetic mechanism is polygenic. The palatal rugae of 17 families (34 parents and 49 children) were classified and recorded, and the data used to construct a statistical analysis system (SAS) cluster map. A positive result would have meant a father clustering with all his children at Level 83, where, in fact, the best result achieved was at Level 5. The best cluster occurred at Level 82 between the ten-year-old boy of Family 7 and the eleven-year-old girl of Family 3. It is thus clear that the palatal rugae cannot be used in a practical procedure to determine paternity.

ABO Blood-Group System↗
PubMed1985

Papillarity of the palatal mucosa.

A sample of 575 palatal casts was studied and found to possess varying degrees of papillary convolutions between and around the palatal rugae. No palatal appliances were worn and no irritative influence was present. A classification of 1-4 was established and the peak incidence was Class II at 48.4% (Class I, being an absence of papillarity, was 7.3%). It is postulated that the presence of a denture may well cause an inflammatory papillary hyperplasia to arise not by a progression through the various stages of denture stomatitis but directly, in an individual with a papillary palate.

Adolescent↗