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Biomedical subjects

J Thomson

Publications and source records attributed to J Thomson.

At least 73 records · Page 4Linked to original sources
PubMed1997

Ubch9 conjugates SUMO but not ubiquitin.

Ubiquitin conjugating enzymes participate in the thioester cascade that leads to protein ubiquitination. Although Ubc9 is homologous to E2 ubiquitin conjugating enzymes we have shown that it is unable to form a thioester with ubiquitin, but can form a thioester with the small ubiquitin-like protein SUMO. Thus Ubc9 is a SUMO conjugating enzyme rather than a ubiquitin conjugating enzyme. Transacetylation of Ubc9 by SUMO is not mediated by the E1 ubiquitin activating enzyme, but by a distinct enzymatic activity. SUMO conjugation to target proteins is mediated by a different, but parallel pathway to ubiquitination.

Acetylation↗
PubMed1997

Serum free prostate-specific antigen in the diagnosis of prostate cancer.

OBJECTIVE: To determine the value of the ratio of free prostate-specific antigen (fPSA) to total PSA (tPSA) in the diagnosis of benign prostatic hyperplasia (BPH) and prostate cancer in a cohort of patients undergoing prostatic transrectal ultrasonography (TRUS). PATIENTS AND METHODS: The study comprised 153 patients (99 with BPH and 54 with prostate cancer) undergoing diagnostic TRUS of the prostate. Patients with a tPSA of > 30 ng/mL were excluded from analysis. Free PSA was assayed using an immunoassay specific for unbound PSA (CanAg Diagnostics, Sweden). Total PSA was measured using the HybriTech Tandem-R PSA immunoradiometric assay in routine clinical use and this estimate was validated using the CanAg tPSA assay. RESULTS: The measurements of tPSA from both assay systems correlated closely. The f/tPSA ratios in patients with prostate cancer were significantly lower than in those with BPH (median values 0.152 and 0.2, respectively, P<0.01). In patients with prostate cancer, the median f/t PSA levels apparently declined with increasing tPSA levels but in those with BPH, the levels of tPSA were not significantly associated with the f/tPSA ratio; the ratios did not vary significantly with age in either group. A f/tPSA ratio at a threshold of 0.16 had positive and negative predictive values of 44% and 74%, respectively; the corresponding values for a tPSA of > 4 ng/mL were 30% and 52%. CONCLUSION: The f/tPSA ratio differs significantly between patients with BPH and cancer but because there is a considerable overlap of f/tPSA ratios between the groups, f/tPSA values alone were not sufficiently specific to be used as a single diagnostic test.

Biopsy↗
PubMed1997

Laryngopharyngeal sensory testing with modified barium swallow as predictors of aspiration pneumonia after stroke.

Improved diagnostic tests that can accurately identify subjects at high risk for aspiration pneumonia (AP) are needed. One measure of this accuracy is the false-negative rate (FNR), which determines the failure of a test to identify a group at high risk. This study compares FNRs for AP among dysphagic stroke patients for two prognostic techniques: modified barium swallow (MBS) alone and MBS combined with laryngopharyngeal sensory discrimination testing (MBS + LPSDT). MBS and LPSDT were performed within 4 weeks of stroke in 20 subjects who were prospectively followed for at least 2 years to identify the frequency of AP. MBS identified 10 patients as not at risk based on the finding of no aspiration on initial MBS; four of these patients developed AP (FNR = 40%). MBS + LPSDT identified five patients as not at risk based on the findings of neither aspiration nor bilateral sensory deficits; none of these patients developed AP (FNR = 0%). The combination of MBS criterion (aspiration) with the LPSDT criterion (bilateral sensory deficits) improves prognostication of outcome in dysphagic stroke patients by identifying a subgroup at high risk for developing AP (nonaspirators with bilateral deficits).

Adult↗
PubMed1997

Identification of Serpulina species associated with porcine colitis by biochemical analysis and PCR.

A PCR system for the detection and identification of group IV spirochetes (Serpulina pilosicoli) was designed to complement biochemical tests, e.g., the hippurate hydrolysis and beta-glucosidase tests, and to verify the accuracy of a previously proposed biochemical classification system. The PCR assay was based on amplification of a segment of the 16S rRNA gene. Both primers were constructed to selectively amplify the 16S rRNA gene of Serpulina pilosicoli. All analyzed Serpulina strains exhibiting the capacity to hydrolyze hippurate and lacking beta-glucosidase activity, including the type strain for spirochetal diarrhea, P43, were amplified with the PCR system. All other tested strains, including type and field strains of different phenotypes of Serpulina species, as well as Salmonella species, Campylobacter species, and Escherichia coli strains, were negative in the assay. Among the tested strains were 18 Scottish field isolates originating from the mucosae of pigs with colitis. A simple classification scheme, suitable for routine classification of porcine intestinal spirochetes, is also presented. The scheme is based on hemolysis, indole production, and the hippurate hydrolysis test.

Animals↗
PubMed1997

Diagnostic pitfalls and therapeutic strategies in the treatment of pancreatic duct haemorrhage.

Haemorrhage via the pancreatic duct, a rare cause of upper gastrointestinal bleeding (GIB), often poses a diagnostic dilemma. We analysed our experience with 10 patients (8 men, 2 women; mean age 44 years, range 34-62) treated during a 12 year period. All had a history of alcohol abuse and presented with major upper GIB requiring a median of 8 units (range 2-40) blood transfusion. Nine had upper abdominal pain at the time of admission and nine had a history of pancreatitis. Upper gastroduodenal endoscopy (median 4; range 1-9), was diagnostic in only one. Side-viewing endoscopy showed bleeding from the pancreatic duct in 7 of 8 patients. Visceral aneurysms were demonstrated in 7 of 9 patients in whom coeliac angiography was carried out: (splenic artery 4, gastroduodenal artery 2, and pancreaticoduodenal artery 1). Two of 4 selective embolisations were successful. Six patients underwent distal pancreatectomy, 1 had gastroduodenal artery ligation and 1 died of coagulopathy following a total pancreatectomy. Pancreatic duct haemorrhage should be considered in patients with unexplained recurrent upper GIB, alcohol abuse and epigastric pain, particularly in those with established chronic pancreatitis. Selective angiography is essential for diagnosis and management. For bleeding sites in the head of the pancreas, embolisation should be attempted to avoid major resection. Distal pancreatectomy is preferred for splenic artery lesions.

Adult↗
PubMed1997

Silent laryngopharyngeal sensory deficits after stroke.

Dysphagia and aspiration are two devastating sequelae of stroke. Recent work has shown that laryngopharyngeal (LP) sensory deficits are associated with aspiration in stroke patients with dysphagia. The phenomenon of silent LP sensory deficits, where the patient exhibits no subjective or objective evidence of dysphagia, yet has an LP sensory deficit, has not been previously described. The aim of this study was to evaluate the sensory capacity of the laryngopharynx in stroke patients who had no subjective or objective complaints of dysphagia. We determined the sensory threshold in the laryngopharynx using air pulse stimulation of the mucosa of the pyriform sinus and aryepiglottic fold. Eighteen stroke patients (mean age 65.6 +/- 11.5 years) and 18 age-matched controls were prospectively evaluated. Normal thresholds were defined as < 4.0 mm Hg air pulse pressure (APP). Deficits were defined as either a moderate impairment in sensory discrimination thresholds (4.0 to 6.0 mm Hg APP) or a severe sensory impairment (> 6.0 mm Hg APP). Stroke patients were followed up for 1 year to determine the incidence of aspiration pneumonia (AP) as verified by chest radiography. In 11 of the stroke patients studied, either unilateral (n = 6) or bilateral (n = 5) severe sensory deficits were identified. The elevations in sensory discrimination thresholds were significantly greater than those in age-matched controls (7.1 +/- 0.6 mm Hg APP versus 2.5 mm Hg APP; p < .01, Wilcoxon score). Among patients with unilateral deficits, sensory thresholds were severely elevated in all cases on the affected side compared with the unaffected side (p < .01, Wilcoxon score). Moreover, the sensory thresholds of the unaffected side were not significantly different from those of age-matched controls. Aspiration pneumonia did not occur in the patients with normal LP sensation or in the patients with unilateral severe LP sensory deficits. However, in the 5 patients with bilateral, severe LP sensory deficits, 2 developed AP, both within 3 months of their LP sensory test. The results of this study showed, for the first time, that stroke patients without subjective or objective clinical evidence of dysphagia could have silent LP sensory deficits. These impairments could contribute to the development of AP following stroke. The findings in this study suggest that LP sensory discrimination threshold testing should not be restricted only to patients with clinical dysphagia.

Aged↗
PubMed1997

Anaemia in pregnant women in eastern Caprivi, Namibia.

OBJECTIVE: To describe the prevalence, character and possible aetiology of anaemia in the study region. DESIGN: A cross-sectional study involving a lifestyle and dietary questionnaire, a clinical examination and an analysis of blood and stool samples. SETTING: Katima Mulilo antenatal clinic, East Caprivi, Namibia. SUBJECTS: 171 pregnant women attending the clinic in September 1995. MAIN OUTCOME MEASURES: Effects on haemoglobin concentration of age, trimester, parity, residential area, sociodemographic factors, malaria, parasites, geophagy, diet, cooking pot used, vitamin and mineral supplementation and malaria prophylaxis. RESULTS: 41.5% of the women were found to be anaemic (haemoglobin < 11 g/dl) and there was a significant risk of their being iron-deficient (P = 0.01). Three maternal characteristics were found to have a significant effect on a woman's risk of anaemia: urban residence (P < 0.05), geophagy (P < 0.01) and the taking of prophylactic chloroquine (P < 0.05). CONCLUSION: Mild anaemia affects a large proportion of the pregnant women in East Caprivi; severe anaemia (< 7 g/dl) is not common. The picture is predominantly one of iron deficiency, possibly complicated by concomitant folate deficiency. There is no single easily identifiable cause of this anaemia; it appears to have a multifactorial aetiology. Further studies on the effect of the current malaria prophylaxis programme are warranted.

Adolescent↗
PubMed1997

Advances in the generation of transgenic pigs via embryo-derived and primordial germ cell-derived cells.

The development of new technologies that would increase the efficiency for generation of transgenic livestock and would overcome some of the problems associated with random insertion of the transgene will greatly benefit animal agriculture. A potential alternative technology to pronuclear injection for the generation of transgenic pigs involves the isolation, culture and genetic manipulation of cell lines that can be reintroduced into the embryo for participation in the formation of the germ cells. We have isolated and cultured pig primordial germ cells (PGC) while maintaining them in an undifferentiated state as determined by morphology and alkaline phosphatase (AP) activity. More importantly, PGC-derived cells were stably transformed with the green fluorescent protein marker driven by the cytomegalovirus promoter. After visual identification of transgenic colonies, the pluripotential characteristics of the transgenic PGC-derived cells were tested by chimaera formation and to date we have identified, by genomic Southern blots, two chimaeric fetuses that contain tissues with the transgene incorporated into their chromosomes. To our knowledge, this is the first report of a chimaeric transgenic pig fetus obtained via a cultured cell line.

Animals↗
PubMed1996

Development of a sandwich ELISA for ovine granulocyte/macrophage colony-stimulating factor.

Recombinant ovine granulocyte/macrophage colony-stimulating factor (rOv GM-CSF) has been expressed in Chinese hamster ovary cells. A stable, cloned line of these cells has been established which secretes high levels (40 mu g ml(-1)) of rOv GM-CSF. Three murine monoclonal antibodies (mAbs) were produced which reacted with rOv GM-CSF on Western blots. These mAbs also neutralised the activity of both recombinant and native Ov GM-CSF in a bone marrow haemopoietic progenitor cell assay. Two of the mAbs, which recognise mutually exclusive epitopes, were selected for the development of a sandwich enzyme-linked immunosorbent assay (ELISA) to measure GM-CSF in biological samples of ovine origin.

Animals↗
PubMed1996

The activation status of ovine CD45R+ and CD45R- efferent lymph T cells after orf virus reinfection.

The dynamics and activation status of CD4+ and CD8+ T-cells differentially expressing the CD45R (220 kDa) antigen were studied in prefemoral efferent lymph draining the site of cutaneous reinfection with orf virus. CD4+, CD45R+ lymphoblasts preceded CD4+, CD45R- lymphoblasts during the first 48 h after reinfection. Thereafter, the output of both total and blast-transformed CD4+, CD45R- T-cells increased in proportion to the CD4+, CD45R+ cells for the duration of the virus reinfection. Output of CD8+, CD45R+ T-cells exceeded that of the CD8+, CD45R+ cells both before and after reinfection. However, within the lymphoblast population, CD8+, CD45R+ and CD8+, CD45R- T-cells increased and decreased in parallel. CD4+, CD45R- and CD8+, CD45R- T-cells produced interleukin-2, interferon-gamma and granulocyte-macrophage colony-stimulating factor after culture for 24 h without exogenous restimulation, whereas CD4+, CD45R+ T-cells produced only interleukin-2. The results show that although both CD45R+ and CD45R- alpha beta receptor+ T-cell subsets are activated as a consequence of virus reinfection in vivo, it is the CD45R- subset that predominates in the later stages of reinfection and is the principal cellular source of lymphokines in the efferent lymph.

Animals↗
PubMed1996

Cytolytic activity and associated serine protease expression by skin and afferent lymph CD8+ T cells during orf virus reinfection.

Following orf virus reinfection in sheep, CD8+ T cells were recruited to the lesion site in the skin during the period of viral replication and appeared in increased numbers in afferent lymph draining the infection site. A proportion of the CD8+ T cells were activated, particularly in the skin, as determined by their expression of the cytolytic cell-associated serine protease, BLT-esterase. This was a useful marker for activated cytolytic cells as there was a good correlation between afferent lymph CD8+ T cell-mediated lysis of autologous orf virus-infected skin cells and their expression of BLT-esterase in vitro. The majority of the cells that expressed BLT-esterase in the skin and lymph were CD8+ T cells and cytolysis in vitro was predominately by the MHC class I antigen presentation pathway. The conclusion is that orf virus reinfection is characterized by limited viral replication and stimulation of an activated CTL response in the skin.

Animals↗
PubMed1996

Evaluation of the 2-mm punch biopsy in dermatological diagnosis.

This prospective study was undertaken to determine whether the 2-mm punch biopsy technique yields specimens of sufficient size and quality to allow a reliable histological diagnosis to be made. A histopathological comparison was made between tissue obtained from a 2-mm punch biopsy and a standard ellipse biopsy taken from a wide range of dermatoses and benign and malignant skin tumours. In 79 of the 84 cases studied, the same histopathological diagnosis was reached with the 2-mm punch biopsy and the standard ellipse. Use of the 2-mm punch biopsy technique produces specimens which allow an accurate histological diagnosis to be made in a wide range of dermatological conditions. Skin biopsy techniques should ideally be quick and easy to perform, yielding specimens of high quality and adequate size while leaving the smallest possible tissue defect and a good cosmetic result. The aim of this study was to compare the effectiveness of the 2-mm punch biopsy with that of the standard ellipse biopsy technique in providing skin specimens which permit an accurate pathological diagnosis to be made.

Biopsy↗
PubMed1995

Haemopoietic cell responses in the blood and bone marrow of sheep infected with the abomasal nematode Telodorsagia circumcincta.

The generation of bone marrow and blood haemopoietic progenitor colony-forming cells (CFCs) in sheep given primary or challenge infections with the nematode parasite Telodorsagia circumcincta is described. Ten days after a primary infection, the frequency of early multipotential-CFCs, eosinophil-CFCs, macrophage-CFCs and mast cell or basophil-CFCs was greater than in controls. These frequencies then declined to pre-infection levels by day 21. Blood CFCs (mainly macrophage-CFCs and eosinophil-CFCs) also increased after infection, indicating a migration of CFCs, presumably to the site of infection. Ten days after challenge infection there was less marked myelopoiesis than in the primary infection on day 10, though both eosinophil-CFCs and mast cell or basophil-CFCs were significantly above control values. Blood CFC output (mainly macrophage-CFCs and eosinophil-CFCs) reached a peak 2-6 days after challenge, evidence of rapid recruitment to the site of infection. Telodorsagia circumcincta infection is therefore associated with an increase in myelopoiesis, particularly for the cell types characteristic of the local inflammatory response to abomasal nematodes. There was no correlation between any of the haemopoietic cell responses measured and worm burdens in individual animals after either primary or challenge infection.

Animals↗
PubMed1995

Recurrent chancriform pyoderma: report of a case with tongue lesions. Is Staphylococcus aureus implicated?

We report a case of recurrent chancriform pyoderma. Staphylococcus aureus was isolated from only one of seven lesions. Immunological responses to S. aureus, as measured by peripheral neutrophil function, were normal. We question the notion that chancriform pyoderma represents an abnormal immune response to a primary staphylococcal infection. To our knowledge, this is only the third reported patient with lesions affecting the tongue.

Adolescent↗
PubMed1995

Adjuvant chemotherapy for non-metastatic osteosarcoma of the extremities in two New Zealand cancer centres.

BACKGROUND: Adjuvant chemotherapy significantly improves survival of patients with non-metastatic osteosarcoma but most of the data come from trials conducted in major international cancer centres. AIM: To review the efficacy and toxicity of an adjuvant chemotherapy regimen used in two regional cancer centres in New Zealand. METHODS: Retrospective review of patients treated for non-metastatic high-grade osteosarcoma of the extremities. The regimen (POMA) consists of high-dose-methotrexate 8 g/m2 and vincristine 1.5 mg/m2 (maximum 2 mg) on days 1 and 8 followed by folinic acid then doxorubicin 50 mg/m2 and cisplatin 100 mg/m2 on day 15. This cycle was repeated every 35 days. Following amputation patients received six cycles while in selected patients two cycles were planned prior to limb salvage surgery followed by a further four cycles. Actuarial survival was calculated using the Kaplan-Meier method. RESULTS: Twenty patients were treated with POMA between 1986 and 1993. Amputation was performed in 16 patients and limb-salvage surgery in four. Sixteen patients (80%) remain alive with no evidence of disease at a median follow-up of 40 months. Thirteen patients (65%) have been continuously disease-free. Actuarial survival at five years is 70%. Seven patients relapsed, six in lungs, of whom four underwent pulmonary metastasectomy; three of these remain free of disease 31, 35 and 40 months later. There was no local relapse. The toxicity of POMA is significant but tolerable. CONCLUSION: The results obtained at two regional cancer centres in New Zealand using POMA compare favourably to those achieved in clinical trials performed at major international cancer centres.

Adolescent↗
PubMed1995

Primary gastrointestinal lymphosarcoma with epitheliotropism in three Shar-pei and one boxer dog.

Three male Shar-pei dogs and one female spayed Boxer dog ranging in age from 4 years, 4 months to 7 years, 8 months had 4-7-week histories of diarrhea, progressive anorexia, weight loss, and vomiting. The dogs were depressed, lethargic, and hypoalbuminemic, with losses of 23-39% of body weight. Endoscopic examination revealed gastric ulceration with areas of mucosal hyperemia and pallor. Small nodules with occasional central depressions were present in three dogs. Gastric and proximal duodenal mucosal biopsies showed neoplastic lymphocytes infiltrating the lamina propria, with invasion of the superficial and glandular epithelial basement membrane. Immunohistochemical evaluation of two dogs was negative for anti-canine IgG and positive for anti-CD3. Necropsy of the Boxer and two Shar-peis confirmed epitheliotropic gastric and small intestinal lymphoma in all three dogs, with mesenteric lymph node and hepatic involvement in two and one dog, respectively.

Animals↗