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Biomedical subjects

B B Scott

Publications and source records attributed to B B Scott.

At least 37 records · Page 2Linked to original sources
PubMed1997

Interleukin-8 and inducible nitric oxide synthase mRNA levels in inflammatory bowel disease at first presentation.

Interleukin-8 (IL-8) and nitric oxide (NO) may be important mediators in the pathogenesis of chronic idiopathic inflammatory bowel disease (CIIBD), but their roles in disease activity in ulcerative colitis (UC) and Crohn's disease (CD) are uncertain. The aim of this study was to measure mRNA for IL-8 and inducible NO synthase (iNOS) in small mucosal biopsies from untreated patients at first presentation and to relate these measurements to the histological levels of polymorph infiltration graded on a ten-point scale. For this purpose, a sensitive enzyme-linked oligonucleotide chemiluminescent assay (ELOCA) was developed to quantitate reverse transcription-polymerase chain reaction (RT-PCR) products amplified from RNA from paired biopsy samples. The levels of IL-8 and iNOS mRNAs were calculated as ratios of the RT-PCR products to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) RT-PCR product. In UC patients, median values of IL-8/GAPDH and iNOS/GAPDH were significantly elevated compared with controls and CD. However, in both UC and CD, the IL-8/GAPDH and iNOS/GAPDH ratios correlated significantly with polymorph infiltration. ELOCA enabled quantitation of multiple mRNAs in small mucosal biopsies from untreated patients with CIIBD and supported a role for IL-8 and iNOS in acute inflammation in both UC and CD.

Adult↗
PubMed1997

Rheumatoid arthritis synovial fibroblast and U937 macrophage/monocyte cell line interaction in cartilage degradation.

OBJECTIVE: To examine the interaction between synovial fibroblasts and macrophages in the context of cartilage degradation. METHODS: An in vitro model of human cartilage degradation was used, in which purified populations of fibroblasts and macrophages were added to a radiolabeled cartilage disc. Cartilage destruction was measured by the percentage of radiolabel release. RESULTS: Fibroblasts, obtained from either rheumatoid arthritis (RA) or osteoarthritis synovial tissue, could mediate cartilage degradation if cocultured with the U937 macrophage cell line. Skin and RA bone marrow fibroblasts had no degradative effect on cartilage. Fibroblast-macrophage contact was not required for cartilage degradation. Cartilage degradation by synovial fibroblasts was inhibited by antibodies to tumor necrosis factor alpha (TNF alpha), interleukin-1 beta (IL-1 beta), and IL-6. Cartilage degradation was almost completely abrogated by a combination of antibodies to TNF alpha and IL-1 beta. Contact between fibroblasts and cartilage was shown to be essential. Antibodies to CD44, but not to intercellular adhesion molecule 1, markedly inhibited cartilage degradation. CONCLUSION: TNF alpha, IL-1 beta, and IL-6 were involved in the activation of synovial fibroblasts to cause cartilage degradation. Cartilage degradation occurred only when fibroblasts were in contact with cartilage. CD44 was demonstrated to be involved in the fibroblast-cartilage interaction.

Antibodies↗
PubMed1997

A one-week quadruple eradication regimen for Helicobacter pylori in routine clinical practice.

BACKGROUND: The addition of omeprazole to 1 week of standard triple therapy (tripotassium dicitrato bismuthate, tetracycline and metronidazole) has given a 98% eradication rate in 54 patients at 4-6 weeks in a research setting. We report the result of a similar 1-week regimen in 52 patients in routine clinical practice assessed at a mean of 8 months. METHODS: Fifty-two patients with peptic ulcer disease and antral biopsies containing Helicobacter pylori sensitive to metronidazole were given a 7-day course of treatment: omeprazole 20 mg b.d., tetracycline 500 mg q.d.s. and tripotassium dictitrato bismuthate chelate tablets 120 mg q.d.s., with metronidazole 400 mg five times daily for the last 3 days only. Completeness of eradication was assessed by a 13C-urea breath test at 4-26 months (mean 8 months). RESULTS: Forty-eight patients (92%) had a negative breath test. Three patients vomited on the last day of the course, otherwise the treatment was well tolerated with the expected minor side-effects of tongue discoloration, nausea and unpleasant taste. CONCLUSIONS: The efficacy of a modified 1-week standard triple therapy with omeprazole is confirmed and shown to be almost as effective in routine clinical practice as a similar regimen in a research setting.

Adult↗
PubMed1997

Simple objective criteria for diagnosis of causes of acute diarrhoea on rectal biopsy.

AIM: To identify simple, objective, accurate histological criteria for distinguishing acute infective-type colitis, chronic idiopathic inflammatory bowel disease, and irritable bowel syndrome on rectal biopsy in patients with acute onset diarrhoea at first presentation, one to 10 weeks after onset. METHODS: Cell counts and measurements of mucosal architecture were made on initial rectal biopsies from 18 patients with acute infective-type colitis, 17 patients with first acute presentation of chronic idiopathic inflammatory bowel disease, and 23 patients with irritable bowel syndrome. The data were analysed by ANOVA and discriminant analysis. RESULTS: Lamina propria cells were mainly in the upper third in irritable bowel syndrome patients. Increased lamina propria cellularity, mainly in the middle third, and numbers of crypt intraepithelial neutrophils distinguished acute infective-type colitis from irritable bowel syndrome in 93% of cases. Chronic idiopathic inflammatory bowel disease differed from irritable bowel syndrome and acute infective-type colitis in a decreased number of crypts and altered crypt architecture. Chronic idiopathic inflammatory bowel disease showed higher lamina propria cellularity, especially in the basal third, with an increased number of lamina propria neutrophils. On discriminant analysis, crypt numbers distinguished 86% of the cases of chronic idiopathic inflammatory bowel disease from the other groups. CONCLUSION: At one week or more from onset, acute infective-type colitis is characterised by a superficial increase in lamina propria cellularity, with only a slight increase in the number of polymorphs. At this stage, chronic idiopathic inflammatory bowel disease is characterised by a transmucosal increase in cellularity together with crypt loss and architectural abnormality. Thus, measurement of mucosal architecture establishes simple, accurate, objective criteria for routine biopsy diagnosis of chronic idiopathic inflammatory bowel disease from acute infective-type colitis and irritable bowel syndrome at initial presentation, one to 10 weeks after onset.

Acute Disease↗
PubMed1996

Analysis of V kappa genes in rheumatoid arthritis (RA) synovial B lymphocytes provides evidence for both polyclonal activation and antigen-driven selection.

To define mechanisms of sustained activation of synovial B lymphocytes in RA, we studied hybridomas established from the local synovial B cell repertoire of two RA patients for V kappa gene expression and for antigen-binding specificity. The analyses revealed that members of the main V kappa families (I, II and III) were utilized at frequencies consistent with random V kappa gene family use. Furthermore, although the hybridomas expressed genes frequently seen in response to other self- and exogenous antigens, only one V kappa I- and two of three V kappa III-expressing hybridomas exhibited reactivity with self-antigens. Nucleotide sequence analysis revealed that all hybridomas, with the exception of rheumatoid factor (RF)-producing hybridomas, expressed V kappa genes highly related to known germ-line genes (99.3-100% homology) and that diversity was generated by deletions and random nucleotide insertions at the V kappa-J kappa junction. Examination of the few nucleotide changes seen with the V kappa genes revealed a predominance of silent to replacement changes. Moreover, most of these changes can be attributable either to allotypic variations or to limited random nucleotide replacements independent of antigen selection. In contrast, one IgG-RF (B4D8) exhibited predominantly replacement nucleotide changes in the complementarity-determining regions, suggestive of antigen-driven selection. The random expression of immunoglobulin variable region genes with no, or little, evidence of mutation in the synovial B lymphocyte repertoire, including natural polyreactive antibodies, alongside mutated IgG-RF, suggest that both polyclonal activation and antigen-driven responses occur in RA synovia.

Amino Acid Sequence↗
PubMed1995

Gastroenterology in the Trent Region in 1992 and a review of changes since 1975.

A survey of all gastroenterologists in the Trent Region (population 4.7 million) showed that in 1992 the number of upper gastrointestinal endoscopies had continued to rise considerably. There were 8.6 per thousand of the population. Colonoscopies had also increased to 1.4 per thousand. There had been a large fall in barium meal examinations to 4.8 per thousand. Barium enema examinations had increased slightly to 5.3 per thousand. The number of endoscopic retrograde cholangiopancreatographies (ERCPs) and variceal sclerotherapies had also increased by 54% and 21% respectively since 1986 and were available in most of the 20 hospitals. Percutaneous endoscopic gastrostomy had been introduced at most hospitals. Emergency endoscopy was readily available at night in only half the hospitals. Fourteen hospitals offered formal open access endoscopy. Intravenous sedation was used routinely in 12 hospitals. The rate for perforation at routine upper gastrointestinal endoscopy was 1 in 4500 and for death was 1 in 20,000. There were serious deficiencies in provision of facilities or staff, or both at 14 hospitals. The total number of gastroenterologists had only increased from 25 to 26 since 1986. Thus endoscopy workload continues to increase and diversify often without adequate staffing, facilities, and funding.

Barium Sulfate↗
PubMed1994

Affinity maturation and isotype switch in clonally related anti-erythrocyte autoantibodies.

The NZB mouse is genetically predisposed to develop, at approximately 6 months of age, a spontaneous and severe autoimmune anaemia caused by production of pathogenic anti-mouse erythrocyte autoantibodies. Molecular analysis of a panel of five anti-erythrocyte monoclonal antibodies (MoAb) derived from splenocytes of unimmunized NZB mice revealed that these autoantibodies all had functionally rearranged genes from the VH J558 family of immunoglobulin genes with closest homology to germline genes H10 and H30. Owing to clustering of nucleotide differences within the CDRs, compared with the germline, it was concluded that these antibodies were most likely generated by an antigen-driven mechanism. We report here further molecular analysis of two (4.16.1 and B4.13.2) of the panel of five anti-mouse erythrocyte producing hybridomas which are apparently clonally related. Nucleotide analysis of the light chain cDNA indicated that both antibodies had closest homology to germline gene V kappa 24 and use J kappa 2 gene. Determination of the functional affinities of the MoAb reveal that B4.13.2 (IgG2a) has a > 10-fold higher affinity for mouse erythrocytes when compared to 4.16.1 (IgG1). This finding supports the view that these two autoantibodies are generated by an antigen-driven mechanism. The proposed mechanism would involve the selection and expansion of a small population of B-lymphocytes by antigen leading to isotype switch, somatic mutation and increased affinity. Our data also point to the possibility that some framework residues may be involved in the binding to antigen.

Amino Acid Sequence↗
PubMed1994

Identification of hybridomas derived from mouse CD5+ B lymphocytes by fluorescent staining for cytoplasmic CD5 expression.

The production of hybridomas derived from CD5+ B lymphocytes is important for studying the immunoglobulin gene repertoire and antibody specificity of this B-lymphocyte subpopulation. However, hybridomas derived from these lymphocytes invariably lose surface membrane expression of CD5 following hybridization. This impedes the unequivocal assignment of the generated hybridomas to the CD5+ B-lymphocyte subpopulation from unsorted, or partially sorted, cells. Recent studies have shown that mRNA transcripts of the CD5 gene and the protein product can be detected in the cytoplasm of some mouse hybridomas, indicating that although surface expression has been lost, they may have been generated from CD5+ B lymphocytes. These studies, however, have been unable to discount completely the possibility that aberrant cytoplasmic expression of the CD5 gene occurred as a direct consequence of the hybridization process. To confirm that cytoplasmic CD5 expression in the hybridomas is in fact directly related to the B-lymphocyte origin we have generated hybridomas from FACS-sorted CD5+ and CD5- murine splenic B lymphocytes, and determined their surface and cytoplasmic CD5 expression by fluorescence-activated cell sorting. Our findings reveal that all hybridomas derived from CD5+ B lymphocytes (nine hybridomas) were negative for surface but positive for cytoplasmic CD5 expression, whereas all hybridomas derived from CD5- B lymphocytes (nine hybridomas) were negative for both surface and cytoplasmic CD5 expression. This finding shows that staining for cytoplasmic CD5 expression provides an accurate method of determining the cellular origin of murine B-lymphocyte hybridomas.

Animals↗
PubMed1993

Molecular mechanisms resulting in pathogenic anti-mouse erythrocyte antibodies in New Zealand black mice.

The New Zealand black (NZB) mouse strain is genetically predisposed to develop, at approximately 6 months of age, a spontaneous and severe autoimmune anaemia caused by production of pathogenic anti-mouse erythrocyte autoantibodies. In order to investigate the molecular mechanisms which lead to anti-mouse erythrocyte autoantibody production we have generated eight anti-mouse erythrocyte MoAbs producing hybridomas from splenocytes of 9- and 12-month-old NZB with spontaneous autoimmune anaemia. IgG2a was the predominant isotype, while IgM, IgG1 and IgG2b were each produced by one hybridoma cell line. All anti-mouse erythrocyte MoAbs were characterized for their antigen specificities. None of the MoAbs cross-reacted with ss- or dsDNA or with other species' erythrocytes, with the exception of one MoAb which cross-reacted with rat erythrocytes. None of the eight hybridomas was demonstrated to express surface or cytoplasmic CD5, suggesting that they derived from CD5- B lymphocytes. All hybridomas when implanted intraperitoneally into BALB/c mice caused anaemia. In order to define the genetic basis and investigate the molecular mechanisms resulting in pathogenic anti-mouse erythrocyte autoantibody production, the pattern of immunoglobulin variable region gene use has been studied. Five of the eight MoAbs whose IgVH genes were sequenced all have functionally rearranged genes from the VH J558 gene family. There is evidence for somatic point mutations in the complementarity-determining regions (CDR) of the IgVH genes in all of these five MoAbs when compared with the closest known germline gene. We suggest that these nucleotide sequence changes are likely to reflect selection by an antigen-driven mechanism. Furthermore, the data indicate that pathogenic anti-mouse erythrocytes are not derived from 'natural' autoantibodies.

Amino Acid Sequence↗
PubMed1993

Iron deficiency anaemia--how far to investigate?

Since 1980 investigations, by this group, of patients with iron deficiency anaemia and no obvious cause, have been limited to upper gastrointestinal endoscopy, with small bowel biopsy, and barium enema. This study attempted to follow up 93 consecutive patients whose anaemia remained obscure after these investigations to determine the outcome and assess the safety of this limited approach. In 1991/92 questionnaires were sent to the general practitioners. Eighty three completed questionnaires were received. Ten patients had died all unrelated to the iron deficiency anaemia. The mean follow up of the 73 living patients was six years (range 4-12). Sixty five (89%) had a normal haemoglobin concentration and only 15 were still taking oral iron. Possible causes for the anaemia were found in 17-non-steroidal anti-inflammatory drug use in 10, menstruation in two, gastrectomy in three, poor nutrition in two. No other cause emerged. It is concluded that this limited investigative approach is safe.

Adult↗
PubMed1993

Inflammatory bowel disease and refractory anaemia (myelodysplasia).

Two patients with colitis and refractory anaemia requiring multiple transfusions are described. In one the anaemia was detected at the onset of colitis before drug treatment; in the other it started after 21 years of treatment with sulphasalazine and during an exacerbation of colitis with perianal abscess for which he had just been started receiving prednisolone, cofluampicil and metronidazole. Glomerulonephritis developed two weeks after the onset of anaemia. These findings together with a recent report of four patients with Crohn's disease and refractory anaemia suggests that the association may be more than coincidental and may be immune mediated.

Aged↗
PubMed1993

Painful rib syndrome--a review of 76 cases.

The painful rib syndrome consists of three features: pain in the lower chest or upper abdomen, a tender spot on the costal margin, and reproduction of the pain on pressing the tender spot. This is a common cause for referral to a general medical/gastroenterology clinic, accounting for 3% of new referrals in Lincoln. Seventy six consecutive patients were studied. The mean age was 48 years and 70% were women. Forty three per cent had been investigated, often extensively, before referral, and eight had had a non-curative cholecystectomy. The case notes from all patients were reviewed and a follow up questionnaire was sent after a mean period of four years to those 72 still alive, of which 56 replied. Thirty nine (70%) still had the pain although all except three had learnt to live with it. Despite a firm diagnosis being given, 25 (33%) patients were referred again to hospital by their general practitioner. All further investigations were negative apart from the finding of gall stones in three patients. The four patients who died had died from unrelated causes. The painful rib syndrome is common but underdiagnosed. It is a safe, clinical diagnosis requiring no investigation. Systematic firm palpation of the costal margin in recommended in all patients presenting with pain in the lower chest or upper abdomen.

Abdominal Pain↗
PubMed1993

Anti-mouse red blood cell monoclonal antibodies use functionally rearranged genes from the VH J558 family and are derived from the CD5- B-lymphocyte subpopulation.

The NZB mouse strain is genetically predisposed to develop, at approximately 6 months of age, a spontaneous and severe autoimmune anaemia caused by the production of pathogenic anti-mouse red blood cell (MRBC) autoantibodies. Although it is believed that the predisposition to autoimmune anaemia is multigenic in nature, the main pathogenic mechanism is attributed to anti-MRBC autoantibodies. We have generated eight anti-MRBC monoclonal antibody (mAb)-producing hybridomas derived from splenocytes of 9- and 12-month-old NZB mice with spontaneous autoimmune anaemia to dissect the molecular and cellular mechanisms resulting in the production of these pathogenic antibodies. The predominant immunoglobulin isotype was IgG2a, produced by five out of eight hybridomas (63%), while IgM, IgG1 and IgG2b were each produced by one hybridoma cell line (12%). Antigen specificity analysis of all eight hybridomas revealed that antibodies from seven out of eight hybridomas were monospecific for MRBC antigen(s). Only one hybridoma (clone 4-16-1) cross-reacted with rat RBC. None of the hybridomas produced antibodies reactive with single- or double-stranded DNA (ss- or dsDNA). Surface and cytoplasmic staining for the CD5 antigen revealed that none of the hybridomas was derived from CD5+ B lymphocytes. All hybridomas cause anaemia when implanted intraperitoneally into normal BALB/c mice. Molecular studies of five of the eight anti-MRBC mAb reveal that all use functionally rearranged genes from the VH J558 gene family. Three of these five mAb used FL16.1 DH genes while one had a CDR3 that resulted from a fusion between two DH genes (SP2.3 and SP2.2) from the SP family.

Anemia↗
PubMed1992

Randomised controlled trial of azathioprine withdrawal in ulcerative colitis.

OBJECTIVE: To determine whether azathioprine can prevent relapse in ulcerative colitis. DESIGN: One year placebo controlled double blind trial of withdrawal or continuation of azathioprine. SETTING: Outpatient clinics of five hospitals. SUBJECTS: 79 patients with ulcerative colitis who had been taking azathioprine for six months or more. Patients in full remission for two months or more (67), and patients with chronic low grade or corticosteroid dependent disease (12) were randomised separately. 33 patients in remission received azathioprine and 34 placebo; five patients with chronic stable disease received azathioprine and seven placebo. MAIN OUTCOME MEASURE: Rate of relapse. Relapse was defined as worsening of symptoms or sigmoidoscopic appearance. RESULTS: For the remission group the one year rate of relapse was 36% (12/33) for patients continuing azathioprine and 59% (20/34) for those taking placebo (hazard rate ratio 0.5, 95% confidence interval 0.25 to 1.0). For the subgroup of 54 patients in long term remission (greater than six months before entry to trial) benefit was still evident, with a 31% (8/26) rate of relapse with azathioprine and 61% (17/28) with placebo (p less than 0.01). For the small group of patients with chronic stable colitis (six were corticosteroid dependent and six had low grade symptoms) no benefit was found from continued azathioprine therapy. Adverse events were minimal. CONCLUSIONS: Azathioprine maintenance treatment in ulcerative colitis is beneficial for at least two years if patients have achieved remission while taking the drug. Demonstration of the relapse preventing properties of azathioprine has implications for a large number of patients with troublesome ulcerative colitis, who may benefit from treatment with azathioprine.

Azathioprine↗