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Biomedical subjects

R E Pounder

Publications and source records attributed to R E Pounder.

At least 55 records · Page 3Linked to original sources
PubMed1998

Focal reduction of villous blood flow in early indomethacin enteropathy: a dynamic vascular study in the rat.

BACKGROUND: Oral indomethacin causes villous shortening, microvascular damage, and distortion, which might induce mucosal ischaemia and necrosis. AIMS: In order to determine the early events in indomethacin induced jejunal injury we examined the temporal relations between morphological damage and changes in villous blood flow following indomethacin. METHODS: In anaesthetised rats, mid jejunal villi were exteriorised in a chamber and observed by fluorescence microscopy. Blood flow in surface capillaries was calculated from velocities and diameters. Indomethacin was applied by both luminal and intravenous routes for 90 minutes, after which the animal was perfusion fixed and the villi were processed for histological examination. Control animals received intravenous or luminal bicarbonate (1.25%). RESULTS: Blood flow slowed in individual villi at 20 minutes, and progressed to complete stasis (in another group) by 45 minutes. Histological examination at 20 minutes revealed microvascular distortion, but no villous shortening; crypt depth:villous height ratios were 0.356 (0.02) in test and 0.386 (0.01) in surrounding villi (p > 0.05). At stasis, the villi under study showed epithelial clumping and were shortened: crypt depth:villous height ratios were 0.92 (0.2) in test and 0.42 (0.06) in surrounding villi (p < 0.02). Vehicle alone had no effect on either blood flow or histology. CONCLUSIONS: Focal slowing of villous blood flow and microvascular distortion precede villus shortening and epithelial disruption, and indicate that damage to surface microvasculature is an early event in indomethacin induced mucosal injury in this model.

Animals↗
PubMed1998

A simple clinical colitis activity index.

BACKGROUND: The appropriate medical treatment of patients with ulcerative colitis is determined largely by the severity of symptoms. Hospital assessment of the severity of disease activity includes investigation of laboratory indices and sigmoidoscopic assessment of mucosal inflammation. AIMS: To develop a simplified clinical colitis activity index to aid in the initial evaluation of exacerbations of colitis. METHODS: The information for development of the simple index was initially evaluated in 63 assessments of disease activity in patients with ulcerative colitis where disease activity was evaluated using the Powell-Tuck Index (which includes symptoms, physical signs, and sigmoidoscopic appearance). The new index was then further evaluated in 113 assessments in a different group of patients, by comparison with a complex index utilising clinical and laboratory data, as well as five haematological and biochemical markers of disease severity. RESULTS: The newly devised Simple Clinical Colitis Activity Index, consisting of scores for five clinical criteria, showed a highly significant correlation with the Powell-Tuck Index (r = 0.959, p < 0.0001) as well as the complex index (r = 0.924, p < 0.0001) and all laboratory markers (p = 0.0003 to p < 0.0001). CONCLUSIONS: This new Simple Colitis Activity Index shows good correlation with existing more complex scoring systems and therefore could be useful in the initial assessment of patients with ulcerative colitis.

Acute Disease↗
PubMed1998

Absence of Escherichia coli, Listeria monocytogenes, and Klebsiella pneumoniae antigens within inflammatory bowel disease tissues.

BACKGROUND: Escherichia coli, listeria, and streptococcal antigens have been found in Crohn's disease tissues. Antibodies to Klebsiella pneumoniae have been found in patients with inflammatory bowel disease and ankylosing spondylitis. The presence of these bacterial antigens in Crohn's granulomas would be of aetiological interest, while their presence in ulcers alone would be more likely to indicate secondary infection. AIM: To investigate inflammatory bowel disease tissues for the presence of these bacteria. METHODS: Formalin fixed, paraffin processed sections from 53 patients (19 ulcerative colitis, 23 Crohn's disease; 11 normal tissues from cancer resections) were studied by immunohistochemistry. Control tissue consisted of normal human small bowel injected submucosally with either E coli, Listeria monocytogenes, Proteus mirabilis, or Klebsiella pneumoniae serotypes K2, 3, 17, 21, 26, 36, and 50, and colonic biopsies from a child with E coli 0114 infection. Tissues were stained by Gram-Twort, and with specific antibodies for E coli (Dako B357), L monocytogenes (Difco 2302-50), and K pneumoniae (Biogenesis 5580-5208) using an immunoperoxidase technique. RESULTS: Positive staining for E coli was observed on the luminal surface epithelium and in ulcers in 35% of Crohn's disease patients, 26% of ulcerative colitis patients, and no normal controls. Superficial staining for L monocytogenes was observed in one case of ulcerative colitis only. Staining for K pneumoniae was observed in one case of ulcerative colitis and one of Crohn's disease. No granulomas, giant cells, or germinal centres stained positively for any of the three bacterial antigens. CONCLUSIONS: These data do not support a primary role for E coli, L monocytogenes, and K pneumoniae in inflammatory bowel disease. The presence of E coli antigens in ulcers suggests secondary infection in these lesions.

Antigens, Bacterial↗
PubMed1998

Comparison of three RNA amplification methods as sources of DNA for sequencing.

DNA products generated from a region of the measles virus genome by three RNA reverse transcription and amplification methods were cloned and sequenced, and the results were compared in order to evaluate the methods' relative fidelities. The methods were: (i) reverse transcription followed by a nested polymerase chain reaction (RT-nPCR), (ii) a combined RT-PCR using rTth polymerase and (iii) nucleic acid sequence-based amplification (NASBA). NASBA was followed by RT-PCR with rTth polymerase or RT using AMV reverse transcriptase to generate DNA products for cloning. Products from all three sets of reactions were cloned into a vector, pT7Blue, and 790 bp of cloned DNA were sequenced and analyzed for base changes to determine the error rates for each amplification method. Sequence analysis of cloned RT-nPCR products showed no errors, whereas cloned rTth mediated RT-PCR products possessed an error rate of 0.38% and cloned NASBA products 0.38%. Products generated by NASBA followed by RT-PCR with rTth polymerase possessed an error rate of 1.9%. The results indicated that cloned DNA products generated by RT-nPCRs possessed least errors and that for NASBA, RT of reaction products before cloning and sequencing was preferable to using RT-PCR.

Animals↗
PubMed1998

What are appropriate end-points for Helicobacter pylori eradication in the treatment of duodenal ulcer?

The end-point of Helicobacter pylori eradication trials in peptic ulcer disease should be the presence or absence of continuing H. pylori infection, and not ulcer healing or recurrence. This is not to suggest that ulcer healing or prevention of recurrence is not the desired clinical end-point. It is to allow large trials to be conducted in a 'patient-friendly' manner and in a shorter time-scale, both of which reduce patient withdrawals, protocol violations and cost. For the same reasons, diagnosis of cure should be made by noninvasive means whenever possible. It is currently impossible to make anything other than generalisations regarding the relative efficacies of modern eradication regiments. As it seems unlikely that definitive head-to-head studies will be performed, the conduct and reporting of current trials needs to be improved and standardised, to allow meaningful comparisons. In particular, the course of each and every patient through the trial should be fully and clearly reported, especially withdrawals and dropouts. The primary efficacy analysis should be the intention-to-treat analysis, with per protocol and modified intention-to-treat analyses also reported, where appropriate.

Clinical Trials as Topic↗
PubMed1998

Measles virus RNA is not detected in inflammatory bowel disease using hybrid capture and reverse transcription followed by the polymerase chain reaction.

Recent epidemiological and immunohistochemical studies have indicated a possible link between measles virus and inflammatory bowel disease (IBD). The aim of this study was to use a sensitive and robust method for the detection of measles virus RNA in IBD and control clinical samples. Peripheral blood mononuclear cells and intestinal resection tissue from IBD and control patients were studied. Two methods were used to determine the presence of measles virus RNA: hybrid capture, using measles virus-specific oligonucleotides linked to paramagnetic solid-phase supports, was carried out on total cellular RNA to enrich for measles virus RNA sequences. Reverse transcription followed by the polymerase chain reaction (RT-PCR) using rTth DNA polymerase was employed for amplification of measles virus N-gene sequences amongst the enriched species. Total RNA was also used for RT-PCR of a housekeeping mRNA species to assess RNA quality. RT-PCR for another region of the measles genome (the haemagglutinin (H) gene) was also undertaken in order to confirm the results obtained using N-gene primers for analysis of these samples. None of the samples were positive for measles N- or H-gene RNA using RT-PCR. Positive control samples confirmed the sensitivity of the methods employed. These results show that either measles virus RNA was not present in the samples, or was present below the sensitivity limits known to have been achieved.

Adolescent↗
PubMed1998

Measles IgM immunoreactivity in patients with inflammatory bowel disease.

AIM: The purpose of our study was to examine measles IgM immunoreactivity in patients with inflammatory bowel disease. PATIENTS AND METHODS: In an International collaborative study, serum measles IgM immunoreactivity was assayed in consecutive outpatients with Crohn's disease (n = 95), ulcerative colitis (n = 79), viral hepatitis (n = 63) and blood donors (n = 30). Two commercial measles assays--enzyme linked immunosorbent assay and indirect fluorescence assay--and a Public Health Laboratory Service (PHLS) "in house" antibody capture radioimmunoassay were used. Results were compared with serum rubella and Epstein-Barr virus-specific IgM immunoreactivity, total serum IgM, and measles IgG immunoreactivity. Twenty patients with inflammatory bowel disease were studied serially over a 4-month period. RESULTS: By enzyme linked immunosorbent assay, the prevalence of raised serum measles IgM immunoreactivity was significantly greater in patients with Crohn's disease 23/95 (24%) and ulcerative colitis 20/79 (27%) compared with hepatitis patients 2/63 (3%) and normal controls 0/30 (0%) (p < 0.001). Indirect fluorescence assay produced significantly more positive results than enzyme linked immunosorbent assay in both Crohn's disease (50/87; 57%) and ulcerative colitis (35/68; 51%) but not in controls (0%) (p < 0.001). In contrast, no sera were positive using MCRIA. In the enzyme linked immunosorbent assay, measles IgM immunoreactivity did not correlate with either total IgM, rubella or Epstein-Barr virus IgM immunoreactivities-which were not raised-measles IgM immunoreactivity, or disease activity. Patients not receiving steroids were more likely to have raised measles IgM immunoreactivity (p < 0.5). All sera tested for Rheumatoid factor were negative. Of 20 patients with inflammatory bowel disease studied by ELISA over a 4-month period, 50% showed raised measles IgM immunoreactivity at some stage. CONCLUSION: The data suggest a specific and fluctuating immune response to measles virus in patients with Crohn's disease and ulcerative colitis, that may be modified by corticosteroid therapy.

Adult↗
PubMed1997

In situ immune responses in Crohn's disease: a comparison with acute and persistent measles virus infection.

The implied aetiological association of measles virus with Crohn's disease would be supported by detection of an immune response to infected cells in affected tissues. This study sought to detect and characterise in situ immune responses to measles virus in both acutely and persistently infected tissues, and in particular, Crohn's granulomata. Tissue sections from patients with Crohn's disease (n = 17), tuberculosis (n = 9), acute intestinal ischaemia (n = 5), acute measles pneumonitis (n = 2), acute measles appendicitis (n = 1), subacute sclerosing panencephalitis (SSPE; n = 1), and measles inclusion body encephalitis (MIBE; n = 1), were examined. Single and double immunohistochemical labelling was performed to identify both cytotoxic lymphocytes (CD8, TIA, perforin, Leu 7, CD45RO, CD45RA) and macrophages (KP1). The relationship of these cells to measles infected cells was examined by double immunolabelling with antimeasles virus nucleoprotein antibody. In both acute measles appendicitis and SSPE, CD8+/TIA cytotoxic lymphocytes (CTL) targeted infected cells. In the cases of Crohn's disease (13/17), MIBE, fatal pneumonitis, and one tuberculous granuloma, that were positive for measles virus, infected cells appeared to be targeted by macrophages rather than CTL. CTL in both tuberculous and Crohn's granulomata were similar in their peripheral distribution, number, and phenotype. The data suggest that measles-specific CTL responses may be attenuated in Crohn's disease compared with acute measles appendicitis and SSPE, and secondly, that an abnormal macrophage response to persistent measles virus infection of the intestine may result in granulomatous inflammation.

Acute Disease↗
PubMed1997

The treatment of Helicobacter pylori infection.

Indications for eradication of Helicobacter pylori infection have widened since the National Institutes of Health consensus conference in 1994. It is argued that they should now include infected patients with non-ulcer dyspepsia, those concerned about the risk of gastric cancer, patients with gastric lymphoma, and those requiring long-term treatment with a proton pump inhibitor. Problems with existing clinical trials are discussed, and the results of different treatment regimens are discussed. It is proposed that future eradication trials should investigate H. pylori-infected subjects identified by serology, rather than ulcer patients, and that eradication is proved only by a pair of 13C-urea breath tests.

Anti-Bacterial Agents↗
PubMed1997

Seven-day treatment for Helicobacter pylori infection: ranitidine bismuth citrate plus clarithromycin and tetracycline hydrochloride.

BACKGROUND: Dual therapy with ranitidine bismuth citrate plus clarithromycin twice daily for 14 days is an effective regimen for eradicating Helicobacter pylori infection. AIM: To determine whether this regimen can be improved by the addition of a second antibiotic, tetracycline hydrochloride, whilst reducing the duration of treatment to 7 days. METHODS: Sixty-one out-patients were enrolled to this open treatment study. All had H. pylori infection, as determined by 13C-urea breath test and, for those undergoing endoscopy, by rapid urease test. Patients were treated with ranitidine bismuth citrate 400 mg. clarithromycin 500 mg and tetracycline hydrochloride 500 mg all twice daily for 7 days. Eradication of H. pylori was assessed by two separate 13C-urea breath tests, the first 28-68 days after the completion of treatment, the second 28-162 days later. H. pylori infection was considered cured if both tests were negative. RESULTS: All 61 patients were included in the intention-to-treat efficacy analysis. Successful eradication of H. pylori was achieved in 55/61 patients (90%; 95% CI; 82-98%). Fifty-nine out of sixty-one patients reported 100% compliance; one patient missed a single dose of medication and the other withdrew at 48 h due to nausea and vomiting. Minor adverse events were reported by 30/61 patients. CONCLUSION: One-week triple therapy with ranitidine bismuth citrate, clarithromycin and tetracycline, all twice daily, is a safe and well-tolerated regimen which eradicates H. pylori in 90% of infected patients.

Adult↗
PubMed1997

Ranitidine bismuth citrate with clarithromycin for the eradication of Helicobacter pylori and for ulcer healing.

BACKGROUND: In a pilot study, ranitidine bismuth citrate (RBC; Pylorid, Tritec) in coprescription with clarithromycin achieved a Helicobacter pylori eradication rate (based on 13C urea breath test alone) of 83%. The aim of the current study was to validate this finding by using three diagnostic tests and a larger group of H. pylori-positive patients with active duodenal ulcer. METHODS: In a blinded study, 95 patients were given either 4 weeks of treatment with RBC, 400 mg bid, alone (RBC400, n = 31) or RBC, 400 mg bid or 800 mg bid, in coprescription with clarithromycin, 250 mg qid for 14 days, followed by 14 days of RBC, 400 mg bid, alone (RBC400 + CLAR and RBC800 + CLAR, respectively; n = 32 for each). Rates of ulcer healing at week 4 and of H. pylori eradication (assessed by antral and corpus urease tests and histology and by 13C urea breath test) at week 8 were compared, together with the incidence of adverse events. RESULTS: All three regimens were effective at duodenal ulcer healing and were tolerated well. The coprescription regimens gave significantly higher observed H. pylori eradication rates (82% and 74% for RBC400 + CLAR and RBC800 + CLAR) compared with RBC400 (0%; p < .001). CONCLUSIONS: RBC in dual therapy with clarithromycin provides excellent H. pylori eradication therapy and is an effective duodenal ulcer healing drug.

Adult↗
PubMed1997

Antineutrophil cytoplasm autoantibodies against bactericidal/permeability-increasing protein in inflammatory bowel disease.

BACKGROUND: Bactericidal/permeability-increasing protein (BPI), a constituent of primary neutrophil granules, is a potent natural antibiotic and an antineutrophil cytoplasm antibody (ANCA) antigen in cases of vasculitis in which the target antigen is neither myeloperoxidase (MPO) nor proteinase-3 (PR3). AIM: To investigate BPI as a possible target antigen for ANCAs in inflammatory bowel disease. METHODS: ANCAs were detected by routine immunofluorescence (IIF) and solid phase enzyme linked immunosorbent assay (ELISA) performed for antibodies to the purified neutrophil granule proteins; MPO, PR3, cathepsin-G, lactoferrin, and BPI in serum samples from 88 patients with inflammatory bowel disease (36 with Crohn's disease, 52 with ulcerative colitis). Thirty patients with bacterial enteritis acted as controls. RESULTS: Significantly more patients with ulcerative colitis were ANCA positive by IIF (60%) than patients with Crohn's disease (28%) or infectious enteritis (23%) (p < 0.001). IgG anti-BPI antibodies were present in 29% of patients with ulcerative colitis, 14% of patients with Crohn's disease, and 23% of patients with infectious enteritis, occurring in 44% of those patients with inflammatory bowel disease who were ANCA positive by IIF. Antibodies to other ANCA antigens were rare. The presence of ANCAs was not related to either disease activity or extent; presence of anti-BPI antibodies was significantly related to both a lower serum albumin concentration (p = 0.001) and a higher erythrocyte sedimentation rate (p = 0.02) in patients with ulcerative colitis, and to colonic involvement in patients with Crohn's disease (p = 0.01). CONCLUSION: BPI is a significant minority target antigen for ANCAs in inflammatory bowel disease that seems related to colonic Crohn's disease and disease activity in ulcerative colitis. Anti-BPI antibodies occur in infectious enteritis.

Adult↗
PubMed1997

Vascular anatomy defines sites of indomethacin induced jejunal ulceration along the mesenteric margin.

BACKGROUND: Indomethacin induces ulceration in the rat jejunum with sparing of the ileum. The ulcers localise between vasa recta along the mesenteric margin of the bowel, observations that have not been fully explained. AIM: To examine the relationship between the localisation of experimental ulcers and the vascular anatomy of the rat small intestine. METHODS: The normal vascular anatomy of the rat jejunum and ileum was studied and compared using arterial carbon ink perfusion. The anatomical localisation of early and advanced lesions induced by indomethacin was examined with particular reference to the vasculature. Mucosal injury induced by feeding vessel ligation for 24 hours or brief ischaemia-reperfusion injury was examined. The existence of anatomically sensitive sites to indomethacin was tested in a two dose study. RESULTS: In the rat jejunum, poorly vascularised sites along the mesenteric margin were highly susceptible to indomethacin induced injury, such sites being absent from the ileum. Villous contraction was a feature of both early indomethacin injury and ischaemia-reperfusion injury in the rat jejunum. Twenty four hour ligation of jejunal vasa brevia selectively induced ischaemic injury along the mesenteric margin. Two doses of indomethacin to rats did not induce greater injury than a single dose. CONCLUSIONS: Results support the hypothesis that the rat jejunum possesses vascularly compromised sites along the mesenteric margin that are susceptible to indomethacin induced injury. Indomethacin may cause ischaemia-reperfusion injury selectively at these sites.

Animals↗
PubMed1997

Ulceration of the ileum in Crohn's disease: correlation with vascular anatomy.

BACKGROUND: Ileal ulcers in Crohn's disease tend to lie along the same side of the bowel wall as the mesenteric attachment; the mesenteric and antimesenteric borders are supplied by short and long arteries, respectively. AIM: To examine the localisation of ileal Crohn's ulcers and to test the hypothesis that predilection of Crohn's ulcers for the ileal mesenteric margin is explained by the existence of end arteries that supply the mesenteric margin. METHODS: The localisation of ulcers in the bowel wall was examined in eight resection specimens of Crohn's disease of the terminal ileum. The vascular anatomy of normal terminal ileum (n = 8) and proximal jejunum (n = 8) postmortem specimens was studied; isolated long and short vessels were ligated before perfusion in four of these specimens. RESULTS: All eight specimens of Crohn's disease of the terminal ileum showed longitudinal ulceration along the mesenteric margin. In the postmortem study, the submucosal vascular plexus derived from ileal, but not jejunal short vessels, comprised end arteries with little or no communication with the submucosal plexus arising from long vessels. Prior ligation of ileal, but not jejunal, short vessels resulted in a filling defect of the submucosal plexus along the mesenteric margin in three of the four specimens. Ligation of ileal and jejunal long vessels did not affect carbon ink perfusion of the bowel wall. CONCLUSIONS: In the human terminal ileum, the short vessels supplying the mesenteric margin are end arteries, and their pathological occlusion might cause ischaemia of this region. These findings support a vascular hypothesis for Crohn's disease and may explain, in part, both the ileal and mesenteric distribution of Crohn's disease ulcers.

Aged↗
PubMed1997

Detection and comparative analysis of persistent measles virus infection in Crohn's disease by immunogold electron microscopy.

AIMS: To determine the specificity of persistent measles virus infection in intestinal samples from Crohn's disease patients using quantitative immunogold electron microscopy. To compare the results with samples from ulcerative colitis, a granulomatous inflammatory control (tuberculous lymphadenitis), and a positive control. METHODS: Formalin fixed, paraffin embedded intestinal tissue from patients with Crohn's disease was reprocessed and stained with antimeasles nucleocaspid protein primary antibody followed by 10 nm gold conjugated secondary antibody. Tissue samples were taken from granulomatous and non-granulomatous areas of the intestine. Intestinal samples from patients with ulcerative colitis, tuberculous lymphadenitis, or acute mesenteric ischaemia were similarly processed. Brain tissue from a patient with subacute sclerosing panencephalitis (SSPE) was used as the positive control. Duplicate sections of all tissues were processed without the primary antibody. Stained specimens were examined by electron microscopy. RESULTS: In Crohn's disease patients, 8/9 foci of granulomatous inflammation and 0/4 foci of non-specific inflammation were positive for measles virus. Of controls, 0/5 non-inflamed intestinal tissues, 1/8 tuberculous tissues, 1/5 ulcerative colitis tissues, and 1/1 SSPE tissues were positive. Gold grain counts per nuclear field-of-view in both Crohn's disease granulomas (43.29) and SSPE (36.94) were significantly higher than in tissues from patients with ulcerative colitis (13.52) or tuberculous lymphadenitis (15.875), and nongranulomatous areas of Crohn's disease (4.89) (p < 0.001, p < 0.001, p = 0.0006, respectively), with no significant difference between Crohn's disease and SSPE (p > 0.1). In both SSPE and Crohn's disease staining was confined to a small population of cells exhibiting characteristic cytopathology. CONCLUSION: These data support a role for measles virus in the aetiology of Crohn's disease.

Adolescent↗
PubMed1997

New developments in Helicobacter pylori eradication therapy.

BACKGROUND: The optimal strategy for the eradication of Helicobacter pylori has yet to be determined. This paper summarizes some of the latest treatment strategies for eradicating H. pylori infection. METHOD: Literature review by author. RESULTS: Successful eradication of H. pylori requires the use of combination therapy involving control of gastric acid secretion together with anti-microbial drugs. The two most popular strategies use either a proton-pump inhibitor or an H2 antagonist plus two antibiotics-usually metronidazole, amoxycillin or clarithromycin. Ranitidine bismuth citrate is a co-precipitate of ranitidine hydrochloride and bismuth citrate, producing a high rate of H. pylori eradication when combined with clarithromycin. Future development of this combination may involve the addition of a second antibiotic. CONCLUSION: Modern combination therapy usually results in an 80-95% H. pylori eradication rate in compliant patients.

Anti-Bacterial Agents↗