PubMed Health⌕ Search

Biomedical subjects

G R Pearson

Publications and source records attributed to G R Pearson.

At least 19 recordsLinked to original sources
PubMed2006

Demonstration of Ollulanus tricuspis in the stomach of domestic cats by biopsy.

Ollulanus tricuspis is a small nematode of the family Ollulanidae, found in the stomach of domestic cats and other felids. Of 131 gastric biopsy samples collected at endoscopic examination, four were shown to contain the parasite. Vomiting was the main presenting sign in three cats and weight loss in the fourth. The stomachs were grossly normal on endoscopic examination. Chronic gastritis was observed histologically in two cases, while the remaining cases were microscopically normal. The significance of the parasite remained undetermined. To our knowledge, this is the first report of O. tricuspis infection in domestic cats in which the diagnosis was made by examining routine endoscopic biopsy samples.

Animals↗
PubMed2006

Influence of colostrum deprivation and concurrent Cryptosporidium parvum infection on the colonization and persistence of Escherichia coli O157 : H7 in young lambs.

Escherichia coli O157 : H7 and Cryptosporidium parvum infections of man have been associated with direct contact with small ruminants. Colostrum protects neonates against gastrointestinal pathogens, and orphan lambs, which are common on petting farms, may be deprived of this protection. In a recent study, it was demonstrated that high shedding of E. coli O157 : H7 by an 8-week-old goat kid was associated with coincidental C. parvum infection. Furthermore, both pathogens were co-located in the distal gastrointestinal tract. It was hypothesized that colostrum deprivation and pre-infection with C. parvum predisposed young ruminants to colonization and increased shedding of E. coli O157 : H7. To test this, 21 lambs 5 weeks of age were divided into four groups as follows: (A) colostrum-deprived and inoculated with E. coli O157 : H7, (B) colostrum-deprived and inoculated with C. parvum and then E. coli O157 : H7, (C) conventionally reared and inoculated with E. coli O157 : H7, (D) conventionally reared and inoculated with C. parvum and then E. coli O157 : H7. C. parvum was detected between 8 and 12 days post-inoculation in most of the infected lambs. At 24 h post-inoculation with E. coli O157 : H7, all lambs were shedding between 5 x 10(4) and 5 x 10(7) c.f.u. E. coli O157 : H7 per gram of faeces. E. coli O157 : H7 was shed in higher numbers in the groups pre-inoculated with C. parvum, whether conventionally reared or colostrum-deprived. Interestingly, for the colostrum-deprived lambs on day 3, a significant difference in shedding of E. coli O157 : H7 was observed (P = 0.038), with the lambs inoculated with E. coli alone yielding higher counts than those pre-inoculated with C. parvum. From day 15 onwards, shedding of E. coli O157 : H7 was highest from the colostrum-deprived C. parvum-infected lambs, then (in descending order of shedding) the colostrum-deprived lambs, the conventionally reared lambs infected with C. parvum, and the conventionally reared animals. In total, four animals were euthanized, two at 24 h and two at 96 h post inoculation with E. coli O157 : H7 (two conventionally reared and two colostrum-deprived). All animals euthanized were from groups pre-inoculated with C. parvum prior to challenge with E. coli O157 : H7. On examination of tissues, in three of the four animals examined, multifocal attaching and effacing lesions were observed in the caecum, colon, rectum and at the recto-anal junction, and were confirmed by immunohistochemistry to be associated with E. coli O157 : H7.

Animals↗
PubMed2006

Bacterial cholangitis/cholangiohepatitis with or without concurrent cholecystitis in four dogs.

OBJECTIVES: To evaluate the clinical, clinical pathology, diagnostic imaging, microbiological and pathological features of cholangitis/cholangiohepatitis in the dog. METHODS: The study design was a retrospective review of cases of bacterial cholangitis/cholangiohepatitis presented to the University of Bristol during the period 1995 to 2000. The diagnosis was made based on hepatic histopathological findings and positive bile culture results. RESULTS: Four dogs met the inclusion criteria. Common presenting signs included anorexia (n=4), jaundice (n=4), vomiting (n=4) and pyrexia (n=2). All four dogs had a leucocytosis or neutrophilia reported at some time in their history along with serum bilirubin elevation. In addition, serum alkaline phosphatase and alanine transaminase activity was increased in all of the dogs in which it was measured both before and at the time of referral. In general, the diagnostic imaging findings were non-specific. Organisms cultured from bile aspirates were Escherichia coli (n=3), Clostridium species (n=2) and a faecal Streptococcus species (n=1). Two cases resolved with medical treatment alone; two with concurrent cholecystitis required cholecystectomy. Following surgery, both of these cases showed a resolution of clinical signs. CLINICAL SIGNIFICANCE: This report highlights the fact that bacterial cholangitis/cholangiohepatitis with or without concurrent cholecystitis should be considered as a potential differential in dogs presenting with signs referable to biliary tract disease.

Alkaline Phosphatase↗
PubMed2005

Attaching-effacing bacteria in animals.

Enteric bacteria with a demonstrable or potential ability to form attaching-effacing lesions, so-called attaching-effacing (AE) bacteria, have been found in the intestinal tracts of a wide variety of warm-blooded animal species, including man. In some host species, for example cattle, pigs, rabbits and human beings, attaching-effacing Escherichia coli (AEEC) have an established role as enteropathogens. In other host species, AE bacteria are of less certain significance. With continuing advances in the detection and typing of AE strains, the importance of these bacteria for many hosts is likely to become clearer. The pathogenic effects of AE bacteria result from adhesion to the intestinal mucosa by a variety of mechanisms, culminating in the formation of the characteristic intimate adhesion of the AE lesion. The ability to induce AE lesions is mediated by the co-ordinated expression of some 40 bacterial genes organized within a so-called pathogenicity island, known as the "Locus for Enterocyte Effacement". It is also believed that the production of bacterial toxins, principally Vero toxins, is a significant virulence factor for some AEEC strains. Recent areas of research into AE bacteria include: the use of Citrobacter rodentium to model human AEEC disease; quorum-sensing mechanisms used by AEEC to modulate virulence gene expression; and the potential role of adhesion in the persistent colonization of the intestine by AE bacteria. This review of AE bacteria covers their molecular biology, their occurrence in various animal species, and the diagnosis, pathology and clinical aspects of animal diseases with which they are associated. Reference is made to human pathogens where appropriate. The focus is mainly on natural colonization and disease, but complementary experimental data are also included.

Animals↗
PubMed2005

Naturally acquired attaching and effacing Escherichia coli in sheep.

In a series of experiments involving the inoculation of sheep with Escherichia coli O157:H7, and subsequent detailed histopathological examination of the intestinal mucosa, attaching-effacing (AE) lesions formed by elements of the natural flora were observed in 18% of animals. These incidental AE lesions typically were small and sparse, and were not associated with clinical disease. It was possible to identify further some of the lesional bacteria, revealing that E. coli O115 had formed lesions in one of the seven affected animals, and similarly E. coli O26 had formed some of the lesions in another. As AE strains, source flocks, housing and feed sources were diverse, a common source of lesion-forming bacteria appears to be unlikely. It is postulated that subclinical AE lesions are a mechanism of persistence of AE bacteria in sheep.

Animals↗
PubMed2005

Colonization of 8-week-old conventionally reared goats by Escherichia coli O157 : H7 after oral inoculation.

Enterohaemorrhagic Escherichia coli O157 : H7 infections of man have been associated with consumption of unpasteurized goat's milk and direct contact with kid goats on petting farms, yet little is known about colonization of goats with this organism. To assess the contribution of flagella and intimin of E. coli O157 : H7 in colonization of the goat, 8-week-old conventionally reared goats were inoculated orally in separate experiments with 1x10(10) c.f.u. of a non-verotoxigenic strain of E. coli O157 : H7 (strain NCTC 12900 Nal(r)), an aflagellate derivative (DMB1) and an intimin-deficient derivative (DMB2). At 24 h after inoculation, the three E. coli O157 : H7 strains were shed at approximately 5x10(4) c.f.u. (g faeces)(-1) from all animals. Significantly fewer intimin-deficient bacteria were shed only on days 2 (P = 0.003) and 4 (P = 0.014), whereas from day 7 to 29 there were no differences. Tissues from three animals inoculated with wild-type E. coli O157 : H7 strain NCTC 12900 Nal(r) were sampled at 24, 48 and 96 h after inoculation and the organism was cultured from the large intestine of all three animals and from the duodenum and ileum of the animal examined at 96 h. Tissues were examined histologically but attaching-effacing (AE) lesions were not observed at any intestinal site of the animals examined at 24 or 48 h. However, the animal examined at 96 h, which had uniquely shed approximately 1x10(7) E. coli O157 : H7 (g faeces)(-1) for the preceding 3 days, showed a heavy, diffuse infection with cryptosporidia and abundant, multifocal AE lesions in the distal colon, rectum and at the recto-anal junction. These AE lesions were confirmed by immunohistochemistry to be associated with E. coli O157 : H7.

Adhesins, Bacterial↗
PubMed2003

Morphological, histological and histochemical studies of the pituitary glands of ovine freemartins.

Freemartins are XX/XY chimaeras that develop as a result of the fusion of the placental circulation of at least one male and one female fetus. The pituitary glands of eight normal ewes at various stages of the oestrous cycle and three rams were compared with those of two male-type and three undifferentiated-type freemartins. The pituitaries were heaviest in the male-type freemartins, and their pattern of gonadotrophs, assessed by differential staining, was more intense than in the normal males. The pituitaries of the undifferentiated-type freemartins weighed less than those of the normal ewes but had more stained gonadotrophs than the normal ewes or rams. In both types of freemartins the pattern of cells resembled that of a castrated male.

Animals↗
PubMed2003

Morphological, histological and histochemical studies of the gonads of ovine freemartins.

Freemartins are XX/XY chimaeras that develop as a result of the fusion of the placental circulation of at least one male and one female fetus. Of 19 freemartin ewes, 13 had testis-like structures, seven of them in an abdominal position and six in an inguinal position. Histologically, their gonads had structures resembling seminiferous tubules and interstitial cells, and grossly, most had structures derived from the mesonephric ducts (vasa deferentia, epididymides and vesicular glands). The other six freemartin ewes had small, undifferentiated gonads that lacked either follicles or seminiferous tubule-like structures. They also lacked any structures derived from the mesonephric ducts. No derivatives of the paramesonephric ducts were detectable in any of the freemartin ewes. The gonads of the male-type freemartins stained immunocytochemically for 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and histochemically for alkaline phosphatase (AP) in a similar way to, but more extensively and intensely than, the gonads of normal rams, and the staining was confined to interstitial cell-like structures. The staining in the undifferentiated-type freemartins was weak, but both 3beta-HSD and AP were present in unidentified cell types.

3-Hydroxysteroid Dehydrogenases↗
PubMed2002

Biomechanical and histopathological changes in the support structures of bovine hooves around the time of first calving.

Hooves were removed from heifers killed two weeks before calving (C-2), and four and twelve weeks post-calving (C+4 and C+12), and from age-matched maiden heifers. Segments were dissected from the anterior walls of lateral hind claws, to include horn, corium and bone, and the biomechanical properties were measured. There was reduced rigidity, both overall and at a physiologically appropriate displacement of 2 mm, and a greater displacement was required to reach initial and maximum support in the hooves of calving, compared with maiden, heifers. Histological examination revealed widened and distorted interdigitating laminae, progressing to C+12 in the hind claws, but with evidence of recovery in the front claws after C+4. Increased connective tissue strength from dorsal to ventral hoof segments was correlated with protein, proteoglycan, pro- and activated matrix metalloproteinase-2, and tissue inhibitors of metalloproteinases, and was inversely correlated with fat, water and collagen content. This implies that mechanical changes reflect alterations in the biochemistry of the connective tissue. This evidence supports the hypothesis that primary causal events associated with calving weaken the connective tissue of the hoof suspensory apparatus, leading to increased susceptibility to clinical lameness associated with sole ulcers and white line disease.

Animals↗
PubMed2001

Inconsistent detection of PrP in extraneural tissues of cats with feline spongiform encephalopathy.

Feline spongiform encephalopathy (FSE), a transmissible spongiform encephalopathy or prion disease of cats, first reported in Great Britain in 1990, is believed to result from the consumption of food contaminated by the agent of bovine spongiform encephalopathy (BSE). The accumulation of PrP in non-neural tissues of cats diagnosed as suffering from FSE was investigated by immunohistochemistry. In the majority of the cats no disease-specific PrP was detected in lymphoid tissues. Small amounts of PrP were detected in the spleen of only two of 13 samples examined, in Peyer's patches of one of the two cases for which suitable material was available, but in the myenteric plexus of all four cats in which sections of intestine were examined. In addition PrP immunostaining was found in the kidney of all the cats with FSE whose kidneys were examined.

Animals↗
PubMed2000

Natural and experimental infection of normal cattle with Escherichia coli O157.

The objective of the study was to determine the effects of inoculating cattle orally with a strain of Escherichia coli O157:H7 (A84/92). However, before they were challenged two of the six calves were found to be infected naturally with a wild-type strain of E coli O157 and two more of them became infected later. The number of daily faeces samples from which the wild-type E coli O157 was isolated ranged from one to 10. After they were inoculated, A84/92 was detected in all the calves' faeces on one to six of the next 14 days, and later from the faeces samples of three calves on two, three, and 11 occasions, the last occasion being between 19 and 51 days after inoculation. Two calves were redosed with A84/92, and the organism was isolated on a further five and 15 occasions, the last being after 20 and 58 days. In three dry cows, A84/92 was isolated from the faeces on three to 11 of the 14 days after they were inoculated. Two of the cows were redosed and from one of them it was isolated on 15 occasions, the last being 44 days after the initial infection; in the other cow no further isolation was made. In three lactating cows, it was detected on three to four of the 14 days after they were inoculated, and similar results were obtained after they were reinoculated. None of the animals showed clinical signs and no lesions were detected in the intestines of the calves. Three calves had a serological response to E coli O157 but, with the exception of one cow which had a slight increase to IgM levels, no serological changes were observed in the adult cattle.

Animals↗
PubMed2000

Frequent HHV-6 reactivation in multiple sclerosis (MS) and chronic fatigue syndrome (CFS) patients.

BACKGROUND: HHV-6 is a ubiquitous virus and its infection usually occurs in childhood and then becomes a latent infection. HHV-6 reactivation has been shown to play a role in the pathogenesis of AIDS and several other diseases. OBJECTIVES: To determine what role HHV-6 infection or reactivation plays in the pathogenesis of multiple sclerosis (MS) and chronic fatigue syndrome (CFS). RESULTS: Twenty-one MS and 35 CFS patients were studied and followed clinically. In these patients, we measured HHV-6 IgG and IgM antibody levels and also analyzed their peripheral blood mononuclear cells (PBMCs) for the presence of HHV-6, using a short term culture assay. In both MS and CFS patients, we found higher levels of HHV-6 IgM antibody and elevated levels of IgG antibody when compared to healthy controls. Seventy percent of the MS patients studied contained IgM antibodies for HHV-6 late antigens (capsid), while only 15% of the healthy donors (HD) and 20% of the patients with other neurological disorders (OND) had HHV-6 IgM antibodies. Higher frequency of IgM antibody was also detected in CFS patients (57.1%) compared to HD (16%). Moreover, 54% of CFS patients exhibited antibody to HHV-6 early protein (p41/38) compared to only 8.0% of the HD. Elevated IgG antibody titers were detected in both the MS and the CFS patients. PBMCs from MS, CFS and HD were analyzed in a short term culture assay in order to detect HHV-6 antigen expressing cells and to characterize the viral isolates obtained as either Variant A or B. Fifty-four percent of MS patients contained HHV-6 early and late antigen producing cells and 87% of HHV-6 isolates were Variant B. Isolates from CFS, patients were predominately Variant A (70%) and isolates from HD were predominately Variant B (67%). Moreover, one isolate from OND was also Variant B. Persistent HHV-6 infection was found in two CFS patients over a period of 2.5 years and HHV-6 specific cellular immune responses were detected in PBMCs from ten CFS patients. CONCLUSION: In both MS and CFS patients, we found increased levels of HHV-6 antibody and HHV-6 DNA. A decrease in cellular immune responses was also detected in CFS patients. These data suggest that HHV-6 reactivation plays a role in the pathogenesis of these disorders.

Antibodies, Viral↗
PubMed1999

Attaching and effacing lesions in the large intestine of an eight-month-old heifer associated with Escherichia coli O26 infection in a group of animals with dysentery.

Escherichia coli O26:K60, with genetic attributes consistent with a potentially human enterohaemorrhagic E. coli was isolated from the faeces of an eight-month-old heifer with dysentery. Attaching and effacing lesions were identified in the colon of a similarly affected heifer examined postmortem, and shown to be associated with E. coli O26 by specific immunolabelling.

Animals↗