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J Spencer

Publications and source records attributed to J Spencer.

At least 163 records · Page 9Linked to original sources
PubMed1995

Location and sequence of rearranged immunoglobulin genes in human thymus.

Thymic B cells are a proliferating B cell population concentrated in normal thymic medulla. They are large cells, some with dendritic morphology, and are not associated with any organized follicular structure. Previous work in this laboratory has shown that most of these B cells are surrounded by tightly adherent thymocytes. The literature on human thymic B cells contains many inconsistencies. There is no consensus on whether they express CD5. Even the existence of thymic B cells has been questioned. In this study we have undertaken the first analysis of rearranged immunoglobulin (Ig) genes, looking in particular for evidence of affinity maturation. The Ig VH genes of human thymic B cells in this study are those of the fetal repertoire, though the resemblence to fetal Ig genes is limited in other respects. They are mostly unmutated, but the presence of mutated sequences suggests that this is not a uniform population, as has been previously indicated by phenotypic studies.

Antigens, CD↗
PubMed1995

Influence of blood group and secretor status on carbohydrate structures in human gastric mucins: implications for peptic ulcer.

1. The content and distribution of carbohydrate was examined in mucus glycopolypeptides from human antral mucosae. 2. The mean amount of carbohydrate per 1000 amino acid residues was found to be similar in glycopolypeptides with A, B or H activity. It was slightly, though significantly, less in glycopolypeptides lacking these determinants, because carbohydrate chains were of a shorter average length than in the A-, B- or H-active preparations. This difference was reflected in the sizes of oligosaccharide-alcohols released from representative glycopolypeptides with alkaline borohydride. 3. Differences between A-, B- or H-active and non-secretor glycopolypeptides in terms of the mean number of carbohydrate chains per 1000 amino acid residues were found to be small, and without significance. 4. The average number of peripheral monosaccharide units per 1000 amino acid residues was greater in A-active than in H-active, and least in non-secretor, glycopolypeptides. This order was reversed for monosaccharide units incorporated into skeletal (core plus backbone) structures. The difference in each case was statistically significant. 5. These findings suggest that the increased risk of peptic ulcer associated with blood group O and non-secretor status is unlikely to be attributable to an inherent deficiency in the protective mucus layer, linked to differences between mucins that are associated with A, B or H activity. Other hypotheses linked to infection with Helicobacter pylori are examined.

Blood Group Antigens↗
PubMed1995

Value of laparotomy in the diagnosis of obscure gastrointestinal haemorrhage.

Over a nine year period a total of 137 patients were investigated for obscure gastrointestinal bleeding on one surgical unit. In 20 patients visceral angiography strongly suggested the presence of caecal or right colonic angiodysplasia. These patients were treated by an appropriate colectomy and they are not considered further in this study. Similarly lesions of the small bowel detected by preoperative investigations are not considered here. Fifty five patients were offered diagnostic laparotomy after the failure of other investigations to establish a diagnosis. Two patients refused. A diagnostic laparotomy was performed in the remaining 53. At operation if no visible lesion was seen an on table enteroscopy was performed using a colonoscope passed per oram and, if necessary, per anum. In nine (17%) patients no cause for bleeding was found. In 18 (34%) patients there was a small bowel vascular anomaly, in 14 (26%) a small bowel tumour, in four (7.5%) a bleeding Meckel's diverticulum, and in eight (15%) other miscellaneous lesions. Laparotomy, with on table enteroscopy where indicated, elucidated the cause of bleeding in 44 patients (83%). It was associated, however, with a postoperative death rate of 7.5% (four patients). After seemingly appropriate surgery, rebleeding occurred in 14 patients (26%). Of 18 patients with small bowel vascular anomalies seven rebled (39%), at an average follow up interval of 32 months.

Aged↗
PubMed1995

E-cadherin expression in intestinal epithelium.

AIMS: To investigate E-cadherin expression in normal and inflamed intestine, in the colonic adenocarcinoma cell line HT29, in normal fetal intestine, and in a fetal gut organ culture model where a T cell mediated enteropathy can be generated; to determine whether expression of E-cadherin changes in intestinal inflammation. METHODS: Immunohistochemistry was used to determine E-cadherin expression in following tissues: frozen and paraffin wax sections of normal and inflamed intestine; HT29 colonic adenocarcinoma cell line cultured on coverslips in the presence or absence of cytokines; frozen sections of fetal small intestinal tissue (gestational age 11-22 weeks); and frozen sections of cultured fetal gut in which a T cell mediated enteropathy had been induced. RESULTS: E-cadherin was strongly and evenly expressed by the epithelium in all specimens of intestine studied. Although there was no change in inflammation generally, in some cases of Crohn's disease groups of glands with the characteristic morphology of "ulcer associated cell lineage" showed lower expression of E-cadherin. In fetal gut organ cultures epithelial expression of E-cadherin was lower when local T cells were activated with mitogens, compared with control explants. By contrast, the HT29 cell line showed low levels of expression which increased after treatment with conditioned medium from activated tonsil cells. CONCLUSIONS: E-cadherin is strongly and evenly expressed by epithelium in normal and inflamed intestine, although an increase in E-cadherin expression in cytokine treated HT29 cells was observed. E-cadherin expression is reduced in the epithelium adjacent to ulcers (ulcer associated cell lineage), possibly to assist regeneration.

Adenocarcinoma↗
PubMed1995

Immunohistochemical analysis of T cell proliferation in normal tonsil and B cell lymphoma.

A double immunohistochemical technique, incorporating MIB1 and CD3, was used to identify proliferating T cells in paraffin wax sections of normal tonsil and B cell lymphomas. The number of double stained T cells as a percentage of the total T cells was then determined. In normal tonsil and follicular lymphoma the follicle centre and T cell zones were counted independently. In normal tonsil very few T cells in the follicle centre expressed MIB1. Proliferating T cells were concentrated in the T cell zones. The same pattern was observed in follicular lymphoma. In contrast, the percentage of T cells expressing MIB1 was higher in mucosa associated lymphoid tissue type lymphoma and lymphocytic lymphoma, suggesting that T cell activation occurs in these tumours. The highest percentage of MIB1 positive T cells was observed in high grade lymphoma. This suggests that transformation to high grade lymphoma is associated with an increase in T cell activation.

Cell Division↗
PubMed1995

Socialization to the culture of a rehabilitation hospital: an ethnographic study.

OBJECTIVES: Most previous research on rehabilitation of patients after spinal cord injuries has dealt with the attainment of outcomes valued by staff members or with the prediction of successful outcomes based on sociodemographic characteristics of patients. This study examined the rehabilitation process from the insider's perspective of an individual patient to determine his view of important adaptive problems and to examine how these problems were addressed. METHODS: Ethnographic methods were used for fine-grained documentation of the experiences of one 30-year-old man with spinal cord injury. Daily interview were conducted with this patient during his 116 days of inpatient rehabilitation. An interdisciplinary research team analyzed the data with the constant comparative method to identify a number of recurring themes. RESULTS: Findings indicate that in addition to learning how to function in the local world of the rehabilitation hospital, the patient also learned a new identify as a person with a long-term disability. DISCUSSION: A central theme was the patient's ongoing attempt to figure out how his future was related to his life before the injury and how he could use previous competencies in adapting to disability. Staff members seemed so intent on teaching the patient new skills that they often discounted the significance of his past experience and failed to engage in helping the patient connect his future life story to his past.

Activities of Daily Living↗
PubMed1995

Colectomy: the role of laparoscopy.

Laparoscopically assisted colonic surgery was performed in 23 patients in the last 12 months. In all cases, after an initial diagnostic laparoscopy, the colon was mobilized laparoscopically. The mesenteric and bowel division was performed extracorporeally, as was the anastomosis. No deaths occurred. There was a 13% complication rate; one patient suffered a late (10 days) anastomotic dehiscence at home, and two patients had postoperative upper respiratory chest infections. The mean number of lymph nodes excised for malignant cases was 12, and the total mean postoperative hospital stay was 7 days. The laparoscopic dissection required 40% of the operating time. Although this is our initial experience, we conclude that laparoscopically assisted bowel surgery replaces one operation with two, is more costly, requires a longer-lasting anaesthetic, and in our hands appears to offer little additional benefit to the patient compared with conventional surgery.

Adult↗
PubMed1994

Characterization of the stability of human and murine thymic B cell/thymocyte rosettes and investigation of unusual immunophenotypic findings.

In this study we have used immunohistochemistry to study the controversial expression of CD2 and cytokeratin by thymic B cells and also the expression of the adhesion molecules CD40 and CD80. The B cells were clearly CD2 and cytokeratin negative, however the majority expressed CD40 and some coexpression of CD80 was observed. We have previously observed that human thymic B cells are surrounded by rosetting thymocytes; a relationship which is maintained when cells are cultured. Here we show that the rosettes are remarkably stable in both man and mouse. They are dependent on intact surface protein but not on divalent cations, active metabolism, or components of the cytoskeleton. The rosettes could not be dissociated with antibodies to CD40 or CD80. Failure to consider such a stable rosette structure would result in sampling biases when purifying thymic B cell populations and could also contribute to some of the more unusual phenotypic findings such as the expression of CD2.

Animals↗