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Biomedical subjects

G R Pearson

Publications and source records attributed to G R Pearson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Small intestinal malabsorption in the horse: an assessment of the specificity of the oral glucose tolerance test.

Specificity of the oral glucose tolerance test (OGTT) for the diagnosis of small intestinal malabsorption in the horse was assessed by comparing the results of OGTT with the results of a histopathological examination of the small intestine in 42 adult horses affected by chronic weight loss. The horses were assigned to three groups on the basis of the results of the test. Five horses were considered to have a normal OGTT absorption result (Group 1); all the horses had a histologically normal small intestine. Twenty-five horses had a partial malabsorption result (Group 2) seven of which had normal small intestinal morphology, whereas the remaining 18 had a variety of pathological lesions including lymphosarcoma, villous atrophy, granulomatous enteritis and eosinophilic gastroenteritis. Twelve of the 42 horses had a total malabsorption result (Group 3), and all had a severe infiltrative lesion in the small intestinal wall (either lymphosarcoma or granulomatous enteritis).

Animals↗
PubMed1991

Naturally acquired Pasteurella multocida infection in rabbits: clinicopathological aspects.

A cohort of 41 New Zealand White rabbits, 35 to 60 days old, from twelve litters were followed for twelve weeks for development of pasteurellosis. Eleven of 19 rabbits in five litters acquired Pasteurella multocida infection. The incubation period was difficult to determine as P. multocida infection was detected both before and after the onset of rhinitis. The response of rabbits to infection varied from subclinical infection to death from systemic pasteurellosis. Atrophy of the maxilloturbinates of the nares was detected in rabbits with chronic rhinitis associated with P. multocida infection.

Animals↗
PubMed1990

Concurrent cryptosporidium and coronavirus infections in an Arabian foal with combined immunodeficiency syndrome.

Combined immunodeficiency syndrome is an inherited disorder of the Arabian breed of horses. Affected foals usually die of infectious disease within the first few months of life, and the respiratory tract is the commonest site of infection. This report describes the clinical and pathological features of a case which showed signs of alimentary and respiratory infections. Intestinal infection by coronavirus (not previously recorded in cases of the syndrome) and cryptosporidia was identified. Histopathological evidence also suggested the presence of an adenovirus infection.

Animals↗
PubMed1990

Melanotic hamartoma of the hind brain in a riding horse.

A 3 1/2-year-old bay gelding of the cob type showed nervous signs and coughing associated with breaking-in and exercise. At post-mortem examination, heavy melanin pigmentation of the meninges of the hind brain and the medulla was identified and, on histological examination, melanin-containing cells were found within connective tissue extending into the medulla. The lesion was considered to be a melanotic hamartoma.

Animals↗
PubMed1990

Protein kinase activity associated with a cell cycle regulated, membrane-bound Epstein-Barr virus induced early antigen.

An Epstein-Barr virus protein associated with the restricted component of the early antigen complex was characterized in this study. This protein was of particular interest because of its homology to polyoma middle T antigen and to the product of the bcl-2 oncogene. The results from this study reveal that this protein had a number of unusual properties in comparison with other polypeptides associated with the early antigen complex. For example, the synthesis of this membrane-associated antigen was regulated by the cell cycle, and its expression was compatible with cell survival. Functional studies reveal that immunoprecipitates containing this protein exhibited a threonine-serine-specific protein kinase activity. The results suggest that this protein might function in both the immortalization and replication cycles of this virus.

Amino Acids↗
PubMed1989

Occurrence of 'attaching and effacing' lesions in the small intestine of calves experimentally infected with bovine isolates of verocytotoxic E coli.

Nine calves (five colostrum-fed, four colostrum-deprived) were challenged with two field strains of Escherichia coli which produced either verocytotoxin 1 (VT1) or verocytotoxin 2 (VT2). Although three colostrum-fed calves had blood and mucus in their faeces, no diarrhoea was observed. Three of the four colostrum-deprived calves had diarrhoea and in two of them severe lesions were detected in the small intestine. Focal changes were detected in the colon of three calves. E coli were associated with the lesions in the small and large intestine and were shown by transmission electron microscopy to be intimately attached to the enterocyte surface with effacement of microvilli (attaching and effacing lesions). This is the first report of E coli which produce VT2 being associated with disease in calves.

Animals↗
PubMed1989

Neoplasia involving the middle ear cavity of dogs.

Eleven cases of neoplasia which involved the middle ear cavity of dogs are recorded. Eight of the tumours originated in the external ear canal and comprised four adnexal tumours, one squamous papilloma and three adenocarcinomas of the ceruminous glands. Papillary adenomas were recognised within the middle ear cavity of two dogs. In one animal the precise origin of an anaplastic carcinoma involving the middle ear could not be determined. Only five of the tumours were amendable to surgical excision and four dogs survived for more than eight months after surgery.

Adenocarcinoma↗
PubMed1989

Neutralization of Epstein-Barr virus-induced ribonucleotide reductase with antibody to the major restricted early antigen polypeptide.

A previous study had established a relationship between the major polypeptide of the Epstein-Barr Virus (EBV)-induced restricted (R) component of the early antigen (EA) complex and the large subunit of ribonucleotide reductase. This association was confirmed in this study by the observation that a monoclonal antibody prepared against the 85-kDa R component reacted in immunoblotting with the protein product (molecular weight approximately 93 kDa) encoded by the Xbal fragment of the B-95-8 strain of EBV. This fragment encodes for both the small and large subunits of this virus-induced enzyme. This size of the reactive protein indicated that it was the large subunit. Direct evidence that the 85-kDa EA-R component was associated with the viral-induced ribonucleotide reductase was provided by enzyme inhibition studies. Two monoclonal antibodies prepared against the tertiary structure of the 85-kDa EA-R antigen significantly inhibited the in vitro activity of the viral-specified enzyme but had no effect on ribonucleotide reductase activity derived from two different cellular preparations. A monoclonal antibody prepared against the denatured form of this antigen was ineffective in neutralizing the virus-specific ribonucleotide reductase as were antibodies to different EBV polypeptides. These results therefore conclusively demonstrate that the 85-kDa EA-R polypeptide is associated with the large subunit of this viral-specified enzyme and further suggest that the active site of the enzyme is associated with the tertiary structure of the large subunit.

Antibodies, Monoclonal↗
PubMed1988

Aerosol infection of calves and mice with Salmonella typhimurium.

The likelihood of airborne spread and infection by Salmonella typhimurium was studied in calves and mice. S typhimurium survived in air sufficiently long to present a significant hazard of airborne spread. In a dry climate (32 per cent relative humidity) its predicted viability five minutes after aerosolization was 4 per cent relative to its initial value. This increased to 24.8 per cent in a humid atmosphere (72 per cent relative humidity). Inhalation of S typhimurium by mice caused disease and death at times dependent upon the dose. Even the lowest dose of about 150 colony forming units (cfu) produced disease. Inoculation of approximately 10(4) to 10(6) cfu S typhimurium by either 'mouth and nose only' or 'whole body' aerosol exposure caused infection in calves. The consequences for the control of salmonellosis in intensive calf husbandry are discussed in the light of this demonstration that airborne transmission can be a primary mode of infection of S typhimurium.

Aerosols↗
PubMed1988

Detection of antigens associated with Epstein-Barr virus replication in extracts from biopsy specimens of nasopharyngeal carcinomas.

By using monoclonal antibodies to different Epstein-Barr virus (EBV) polypeptides in combination with immunoblotting, we detected antigens associated with EBV replication in extracts from nasopharyngeal carcinoma (NPC) biopsy specimens. Major polypeptides associated with both the diffuse and the restricted components of the early antigen (EA) complex were found in extracts from nine of nine NPC biopsy specimens. Cells from an additional NPC biopsy specimen, passaged repeatedly in nude mice, were found to be positive for the major EA (restricted) polypeptide. This approach revealed that extracts from three of 14 biopsy specimens form other benign and malignant diseases also expressed these viral polypeptides. Therefore, for the first time, these results conclusively demonstrate the presence of EA polypeptides in extracts from NPC biopsy specimens. This finding provides at least a partial explanation for the reported prognostic value of antibodies to this antigen in patients with this disease.

Antibodies, Monoclonal↗
PubMed1988

Development of an enzyme-linked immunosorbent assay (ELISA) for detecting IgA antibodies to the Epstein-Barr virus.

A 3-step enzyme-linked immunosorbent assay (ELISA) was developed for detecting IgA antibodies to purified Epstein-Barr virus (EBV) polypeptides. The 3-step procedure included the use of a mouse anti-human IgA monoclonal antibody (MAb) to amplify the IgA reaction. The 2 major EBV proteins used in this assay were the 125-kDa component (gp125) associated with the viral capsid antigen (VCA) complex and a major glycoprotein (gp250/200) associated with the membrane antigen (MA) complex. Eighty-two sera were tested on ELISA plates containing either both of the glycoproteins or each one separately. These included 45 IgA antibody-positive sera from patients with nasopharyngeal carcinoma (NPC). With these sera, there was a good correlation, both qualitatively and quantitatively, between results with the immunofluorescence (IF) and ELISA procedures. Although most IgA antibody-positive sera contained antibodies reactive with both gp125 and gp250/200, a number of sera contained antibodies reactive with one of the glycoproteins but not with both. The data indicated that both of these glycoproteins should be used in assays for detecting IgA antibodies to EBV, to avoid false-negative results. This assay should be useful for screening large populations for IgA antibodies to EBV and also possibly for monitoring disease course in patients with NPC.

Antibodies, Viral↗
PubMed1988

Antigenic analysis of the Epstein-Barr virus major membrane antigen (gp350/220) expressed in yeast and mammalian cells: implications for the development of a subunit vaccine.

The Epstein-Barr virus (EBV) major surface membrane antigen, gp350/220, was expressed in recombinant yeast cells and in several recombinant mammalian cell lines. Each of the expressed proteins was analyzed for its ability to bind to a panel of anti-gp350/220 monoclonal antibodies and to a series of anti-EBV positive human sera. The antigens also were used as immunogens for the immunization of rabbits. Each expressed protein was found to be unique both in its pattern of reactivity to the various antibodies and in the spectrum of antibody induced following animal immunization. These results suggest that cell-specific post-translational modifications critically influence the antigenic presentation of the expressed proteins. Nonetheless, all of the mammalian cell-derived versions of the membrane antigen were found capable of inducing EBV-specific neutralizing antibodies.

Animals↗
PubMed1988

ELISA tests and monoclonal antibodies for EBV.

Monoclonal antibodies have now been prepared against a number of the major polypeptides associated with the different EBV-induced antigenic complexes. These antibodies have made it possible to purify and characterize most of these polypeptides and to identify the viral genes encoding for these proteins. In addition, new ELISA tests have been developed which measure antibodies in different immunoglobulin classes against the purified polypeptides. These assays have been useful in the diagnosis of EBV-associated diseases in clinical laboratories. The development of these antibodies and their application to the development of the new ELISA tests will be reviewed in this paper.

Antibodies, Monoclonal↗
PubMed1988

Recommended procedures for the diagnosis of persistent active herpesvirus infections.

While reliable tests are available to diagnose acute herpesvirus infections, this does not apply equally well to the identification of chronic active or recurrent infections. Common serology in most cases is not very reliable, unless the antibody response is carefully dissected to determine the response to some early antigens related to viral replication, such as against EA complex in Epstein-Barr virus infections. There are a number of techniques that hold some promise for the future: antigen demonstration by monoclonal antibodies such as in the shell vial assay or in tissue culture cells exposed to body fluids; in situ hybridization for viral DNA and polymerase chain reaction; and antigen assays by combined blotting/monoclonal antibody techniques. In developing meaningful parameters for defining persistent active or reactivated herpesvirus infections, techniques for quantitating virus and/or antigen should be helpful.

Antigens, Viral↗
PubMed1988

The sites of early viral replication in feline infectious peritonitis.

The sites of early replication of feline infectious peritonitis virus were studied following oral inoculation of specific-pathogen-free (SPF) cats with virus grown in cell cultures. Viral antigen was first detected by immunofluorescence in the tonsils and small intestine within 24 h of inoculation, and was later found in caecum, colon, mesenteric lymph nodes and liver. However, histological changes in the gut did not appear until relatively late in the course of infection. Virus was recovered from the oropharynx and the faeces from as early as the second or third day after inoculation, and shedding continued until euthanasia.

Animals↗