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Biomedical subjects

T A Casey

Publications and source records attributed to T A Casey.

7 recordsLinked to original sources
PubMed1992

Characterization of Serpulina (Treponema) hyodysenteriae and related intestinal spirochetes by ribosomal RNA gene restriction patterns.

Serpulina (Treponema) hyodysenteriae strain A-1 partially purified rRNA, labelled with photobiotin, was used as a non-radioactive probe to identify the rRNA gene restriction patterns of S. hyodysenteriae strains and other spirochetes. Sau3A restriction enzyme digests resulted in similar rRNA gene restriction patterns in S. hyodysenteriae strains from five different countries. Some S. hyodysenteriae strains could be differentiated by variations in their rRNA gene restriction patterns after cleavage of DNA by restriction enzymes SspI or BglII. S. innocens and Treponema succinifaciens, non-pathogenic pig intestinal spirochetes, had rRNA gene restriction patterns that differed markedly from the S. hyodysenteriae patterns, and from each other.

Animals↗
PubMed1992

Susceptibility of porcine intestine to pilus-mediated adhesion by some isolates of piliated enterotoxigenic Escherichia coli increases with age.

Two porcine isolates of enterotoxigenic Escherichia coli (ETEC) (serogroup O157 and O141) derived from fatal cases of postweaning diarrhea and lacking K88, K99, F41, and 987P pili (4P- ETEC) were tested for adhesiveness to small-intestinal epithelia of pigs of different ages. Neither strain adhered to isolated intestinal brush borders of newborn (1-day-old) pigs in the presence of mannose. However, mannose-resistant adhesion occurred when brush borders from 10-day- and 3- and 6-week-old pigs were used. Electron microscopy revealed that both strains produced fine (3.5-nm) and type 1 pili at 37 degrees C but only type 1 pili at 18 degrees C. Mannose-resistant in vitro adhesion to brush borders of older pigs correlated with the presence of fine pili. These strains produced predominantly fine pili in ligated intestinal loops of both older and newborn pigs, but adherence was greater in loops in older pigs. Immunoelectron microscopic studies, using antiserum raised against piliated bacteria and absorbed with nonpiliated bacteria, of samples from brush border adherence studies revealed labelled appendages between adherent bacteria and intestinal microvilli. Orogastric inoculation of pigs weaned at 10 and 21 days of age indicated significantly (P less than 0.001) higher levels of adhesion by the ETEC to the ileal epithelia of older pigs than to that of younger ones. We suggest that small-intestinal adhesion and colonization by these ETEC isolates is dependent on receptors that develop progressively with age during the first 3 weeks after birth. Furthermore, our data are consistent with the hypothesis that the fine pili described mediate intestinal adhesion by the 4P- ETEC strains studied.

Age Factors↗
PubMed1992

Pathogenicity of porcine enterotoxigenic Escherichia coli that do not express K88, K99, F41, or 987P adhesins.

Three-week-old weaned and colostrum-deprived neonatal (less than 1 day old) pigs were inoculated to determine the pathogenicity of 2 enterotoxigenic Escherichia coli isolates that do not express K88, K99, F41, or 987P adhesins (strains 2134 and 2171). Strains 2134 and 2171 were isolated from pigs that had diarrhea after weaning attributable to enterotoxigenic E coli infection. We found that both strains of E coli adhered in the ileum and caused diarrhea in pigs of both age groups. In control experiments, adherent bacteria were not seen in the ileum of pigs less than 1 day old or 3 weeks old that were noninoculated or inoculated with a nonpathogenic strain of E coli. These control pigs did not develop diarrhea. Antisera raised against strains 2134 and 2171 and absorbed with the autologous strain, grown at 18 C, were used for bacterial-agglutination and colony-immunoblot assays. Both absorbed antisera reacted with strains 2134 and 2171, but not with strains that express K99, F41, or 987P adhesins. A cross-reaction was observed with 2 wild-type K88 strains, but not with a K12 strain that expresses K88 pili. Indirect immunofluorescence with these absorbed antisera revealed adherent bacteria in frozen sections of ileum from pigs infected with either strain. We concluded that these strains are pathogenic and express a common surface antigen that may be a novel adhesin in E coli strains that cause diarrhea in weaned pigs.

Adhesins, Escherichia coli↗
PubMed1992

Prevalence of mitral valve prolapse in keratoconus patients.

Fifty patients with advanced degrees of keratoconus, requiring corneal transplantation, were screened for mitral valve prolapse by two dimensional echocardiography. The overall prevalence of 58% was found to be statistically higher than the prevalence of 7% found in a group of age and sex-matched controls. It was also found to be higher than the previously reported prevalence of 38% in a group of keratoconus patients with similar age and sex match to our series. The findings of our study in conjunction with the histopathological and biochemical similarities between the two conditions strongly suggest that they may be different manifestations of similar defects in collagen metabolism.

Adolescent↗
PubMed1978

Posterior polymorphous keratopathy.

Seven cases with posterior polymorphous changes of the cornea are reported. After clinical and pathological examination of the above cases, as well as a short review of the literature, the following points are made: (1) Some cases are congenital, being either familial or sporadic, but others are acquired. (2) The term "posterior polymorphous keratopathy" covers all the variants of the condition and is preferred to the traditional "posterior polymorphous dystrophy". (3) The congenital type is a mild variant of the mesodermal dysplasia, whereas the acquired type follows local disease. (4) The condition can be static, but over 50% of cases are slowly progressive, calling for penetrating keratoplasty.

Aged↗
PubMed1976

HLA matching and corneal grafting.

A series of 200 cases of full-thickness corneal allografts have been followed to determine whether HLA and ABO incompatibility influence prognosis of the grafts. 85% of patients with avascular corneas had clear, functioning grafts one year after transplantation. Only 33% of patients with severely vascularised corneas had successful grafts one year after transplantation. A significant association was found between severe vascularisation of the patient's cornea and irreversible graft rejection. In this group of patients, the proportion of grafts functioning was found to be ranked according to the number of HLA antigens shared by graft donor and recipient. Patients receiving grafts matching for 2 HLA antigens showed a failure-rate due to irreversible rejection of 26% at one year, in comparison with 57% and 62% of grafts matching for 1 or 0 HLA antigens respectively. ABO incompatibility or ABO phenotype of the recipient did not influence graft prognosis. The results indicate that patients with severely vascularised corneas should receive HLA-matched corneal grafts. The institution of HLA-typed cornea "banks" for treatment of such patients is advocated.

ABO Blood-Group System↗