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.

Similarities between ileal Crohn's disease and indomethacin experimental jejunal ulcers in the rat.

BACKGROUND: Both Crohn's disease ileal ulcers and indomethacin-induced jejunal ulcers in the rat have a predilection for the mesenteric margin of the bowel wall. Unlike the anti-mesenteric margin, the mesenteric margin is supplied by small end-arteries that might render it more sensitive to ischaemic injury. AIM: To examine, in both situations, the histological relationship between the precise localization of small bowel ulcers and the mesenteric margin. METHODS: Ileal Crohn's disease ulcers identified in surgical resection specimens (n=5) and indomethacin-induced lesions in the rat jejunum (n=6) were examined macroscopically and histologically. RESULTS: In both the human ileum and the rat jejunum, ulcers occurred consistently along the mesenteric margin, with the most extensive mucosal injury occurring at two adjacent sites on either side of the midline of this margin. At these two sites, feeding arteries entered the muscularis propria. CONCLUSIONS: For anatomical reasons apparently related to the vasculature of the human and rodent small bowel, specific sites along the mesenteric margin are susceptible to Crohn's disease ulceration and NSAID damage, respectively.

The colonic mesenteric margin is most susceptible to injury in an experimental model of colonic ulceration.

BACKGROUND: Crohn's disease ileal ulcers and indomethacin-induced jejunal ulceration in the rat tend to occur in the mucosa nearest to the mesentery (mesenteric margin), an area of the bowel wall that has a critical blood supply. Mercuric chloride induces caecal and colonic ulceration in the Brown Norway rat. AIM: To examine whether the mesenteric margin is more sensitive to injury by a substance known to be vasculotoxic in the caecum and colon. METHODS: Brown Norway rats received a single subcutaneous dose of either mercuric chloride 1 mg/kg or saline. The gastrointestinal tract was examined macro- and microscopically for lesions 48 h later. The vascular anatomy of the normal rat colon and caecum was also examined using the carbon ink perfusion technique. RESULTS: Mercuric chloride induced caecal and colonic ulceration preferentially along the mesenteric margin of the bowel wall. Histologically, the lesions showed mucosal necrosis and neutrophil infiltration. There was also extensive vascular degeneration/necrosis with microaneurysm formation and extensive submucosal haemorrhage. Cellular infiltration of the vasculature was not a feature. The caecal and colonic mesenteric margins in control rats were supplied by small end arteries. CONCLUSIONS: The colonic and caecal mesenteric margins are susceptible to injury by mercuric chloride, a chemical known to induce haemorrhagic vasculopathy in the rat gastrointestinal tract. The large bowel mesenteric margin may be susceptible to injury by mercuric chloride because of the critical blood supply to that side of the bowel wall.

Review article: the pharmacological implications of leucocyte-endothelial cell interactions in Crohn's disease.

The importance of leucocyte-endothelial cell interactions in the inflammatory process is now recognized. In Crohn's disease, we have proposed that these interactions mediate not only the development of the parenchymal cell infiltrate, but also initiate a process (multifocal gastrointestinal infarction) that leads to ischaemic damage to the bowel wall. We review data on the actions of drugs in the treatment of Crohn's disease and, where known, we highlight their effects on leucocyte adhesion to the endothelium. Corticosteroids inhibit adhesion by inhibiting production of interleukin-1, tumour necrosis factor, interferon gamma, leukotrienes and platelet activating factor. Drugs liberating 5-aminosalicylate inhibit leukotriene production. Cyclosporin inhibits T-cell activation, and amplification of the immune response. Inhibition of leucocyte--endothelial cell interactions probably accounts for some of the beneficial effects of these drugs in Crohn's disease.

Reversal and protection against indomethacin-induced blood stasis and mucosal damage in the rat jejunum by a beta3-adrenoceptor agonist.

BACKGROUND: In the rat, indomethacin causes jejunal villous shortening, microvascular distortion, and blood stasis prior to ulceration. The beta3-adrenoceptor agonist CL316,243 (CL) prevents both the early histological changes and ulceration. AIM: To test the hypothesis that the beta3-adrenoceptor agonist CL316,243 exerts its protective effect by prevention and/or reversal of blood flow changes in the rat jejunum exposed to indomethacin. METHODS: In anaesthetized rats, jejunal villous blood flow was measured in surface capillaries using fluorescence microscopy. Stasis of superficial capillary blood flow was induced by combined topical and i.v. indomethacin (100 microg/mL, 2.8 x 10(-4) M). To examine the effect of CL on blood stasis, CL was applied either i.v. (1 mg/kg) or luminally (100 microg/mL, 2.5 x 10(-5)M) at the onset of stasis. Prophylactic protection was assessed by giving i.v. CL simultaneously with indomethacin. Results were compared with controls which received luminal saline applied at blood stasis. The effect of i.v. CL (1 mg/kg) alone, or luminal CL (100 microg/mL) alone on basal villous blood flow was also examined. The small intestines were perfusion-fixed with 10% formol saline, and removed for histology, n = 5 for all groups. RESULTS: Luminal CL given at stasis reversed indomethacin-induced stasis within 10 min, whereas i.v. CL did not. Pretreatment with i.v. CL prevented the onset of stasis. Basal blood flow was raised slightly only by luminal CL. CONCLUSION: The beta-adrenoceptor agonist CL316,243 can protect against indomethacin-induced blood stasis in rat jejunal villi.

Endothelial changes precede mucosal ulceration induced by indomethacin: an experimental study in the rat.

BACKGROUND: Indomethacin has been shown to damage the villous microvasculature concomitant with alterations in villous blood flow in the rat. AIM: To test the hypothesis that alterations in blood flow result from ultrastructural damage to microvasculature endothelium. METHODS: In anaesthetized rats, jejunal villi were exteriorized in a chamber and blood flow in surface capillaries visualized by fluorescence microscopy. Villi were exposed both luminally and systemically to indomethacin (100 microg/mL) for 10 min or until blood slowing or stasis had occurred in superficial capillaries (n=3 per group). Control animals received both a luminal and intravenous vehicle for 45 min (n=3). The small intestines were vascular perfusion-fixed with 1.5% glutaraldehyde and studied by transmission electron microscopy. RESULTS: All controls appeared to be ultrastructurally normal. A 10 min exposure to indomethacin had no effect upon the epithelium but resulted in mild endothelial vacuolization and the development of small finger-like projections into the lumen of villus surface microvasculature. At the point of blood slowing, villus tip epithelium was again normal but the endothelial vacuolization and finger-like projections became more obvious. The endothelial projections and vacuolization became severe at the point of blood stasis; this also coincided with epithelial degeneration. CONCLUSION: This study shows that villus surface microvasculature is the earliest site of morphological damage after indomethacin exposure.

Dexamethasone promotes ulcer plugging in experimental enteritis.

AIM: We investigated the effect of dexamethasone on indomethacin-induced ulceration in the rat. METHODS: Groups of four rats received oral indomethacin (15 mg/kg) and the jejunal mucosa was examined 24 h later for mucosal ulceration. Three of the groups received oral dexamethasone (1, 3 and 6 mg/kg) 0.5 h prior to indomethacin, while the fourth received vehicle. Haematological evaluation was performed and ulcers were assessed both histologically and immunohistochemically. RESULTS: Indomethacin caused multifocal jejunal ulceration that was reduced only by the highest dose of dexamethasone (6 mg/kg). Indomethacin caused a significant fall in the blood haemoglobin concentration that was prevented by dexamethasone at all doses. The ulcers induced by indomethacin alone were deep, punched-out and haemorrhagic while the ulcers arising in rats pre-treated with dexamethasone (all doses) were 'plugged' by a white fibrino-purulent exudate. Histologically, the dexamethasone ulcer exudate was composed of bacteria, fibrin, mucus and a significant increase in the numbers of neutrophils. Dexamethasone alone had no significant pathological effect on the small intestine. CONCLUSIONS: We report the observation that dexamethasone at high doses inhibits indomethacin-induced jejunal ulceration in the rat while at low doses it promotes 'plugging' of ulcers with bacteria, fibrin, mucus and neutrophils that probably reduces haemorrhage from the ulcer base.

Ulceration, fibrosis and diaphragm-like lesions in the caecum of rats treated with indomethacin.

BACKGROUND: Patients on nonsteroidal anti-inflammatory drugs can develop curious intestinal fibrotic diaphragms. METHODS: Groups of rats received indomethacin mixed into a powdered diet at 3 mg.kg/day for 6 and 12 weeks and 6 mg.kg/day for up to 6 weeks. In an attempt to reproduce a human dosing regimen, another group of rats, for a total of 30 weeks, received consecutive periods of indomethacin at 3 mg.kg/day for 12 weeks, 4.5 mg.kg/day for 1 week, 6 mg.kg/day for 1 week, control diet for 6 weeks, 4.5 mg.kg/day for 2 weeks and finally, a control diet for a healing period of 8 weeks. Control rats received powdered diet alone. At termination, the small and large intestines were examined macroscopically and histologically. RESULTS: Indomethacin caused microcytic anaemia, hypoalbuminaemia, small intestinal ulceration, caecal ulceration and inconspicuous raised mucosal lesions in the caecum that histologically showed submucosal fibrosis with disruption and thickening of the apical muscularis mucosae. No control rats showed any abnormality. CONCLUSION: These fibrotic lesions of the rat caecum resemble human diaphragms and may arise from healed caecal ulcers.

Pre-ulcerative villous contraction and microvascular occlusion induced by indomethacin in the rat jejunum: a detailed morphological study.

BACKGROUND: In indomethacin-induced jejunal ulceration in the rat, villi undergo both early microvascular injury and shortening that may involve activation of villous smooth muscle. AIM: This study sought to substantiate light microscopic observations using three-dimensional imaging of early villous architectural changes in response to indomethacin. METHODS: At both 2 and 6 h after oral indomethacin 15 mg/kg or vehicle to groups of rats, the vasculature of the small intestine was visualised by both carbon-ink perfusion/confocal microscopy and injection casting. The mucosa was also examined for lesions by dissection microscopy and scanning electron microscopy. RESULTS: In indomethacin-dosed rats examined by scanning electron microscopy and histology, the mucosa at 2 h showed villous shortening and wrinkling of the surface epithelium without epithelial loss; at 6 h, the mucosa was flattened, often with epithelial loss to expose a 'contracted' villous core. Examination of the 'vasculature in carbon-injected tissues indicated significant reductions of both mucosal height and inter-capillary distance at both 2 and 6 h post-indomethacin. Scanning electron microscopy of injection casts at 2 and 6 h indicated similar changes. These changes were not seen in control tissues. CONCLUSION: Histology, confocal microscopy and scanning electron microscopy support the proposal that villous shortening with disruption of surface capillary architecture are early changes in the ulcerative enteropathy induced by nonsteroidal anti-inflammatory drugs.

Intestinal site-dependent susceptibility to chronic indomethacin in the rat: a morphological and biochemical study.

BACKGROUND: The cyclo-oxygenase inhibitor indomethacin induces a pattern of gastrointestinal injury in the rat that is site-dependent. This study compared the extent of injury to different regions of the rat intestine (small intestine, caecum and colon) with the corresponding changes in arachidonic acid metabolism in these areas, following long-term, low-dose indomethachin. METHODS: Rats (eight per group) received either indomethacin (3 mg.kg/day) or control diet for either 6 or 12 weeks. At termination animals were bled, examined both macroscopically and microscopically for ulcers, and assayed for blood thromboxane B2, intestinal tissue prostaglandin E2 content and production of leukotriene B4. In a further eight animals luminal indomethacin concentrations from the small intestine, caecum and colon were measured following 6 weeks of chronic drug ingestion. RESULTS: At 6 weeks, macroscopic ulcers were observed in 2/8 (small intestine), 3/8 (caecum) and 1/8 (colon) animals. The corresponding ratios at 12 weeks were 5/8, 8/8 and 0/8. In control animals, a site-dependent gradient of the prostaglandin E2 concentration was found. In indomethacin-dosed animals the intestinal prostaglandin E2 content was reduced significantly in the caecum at 6 weeks, and in all tissues at 12 weeks. An increased leukotriene B4 production was observed in the caecum only, at 12 weeks (P < 0.01), and the blood thromboxane B2 was reduced at both time points (P < 0.05). CONCLUSION: There is a site-dependent gradient of the prostaglandin E2 concentration in the rat intestine. The rat caecum is particularly sensitive to long-term low-dose indomethacin, both in terms of chronic intestinal inflammation and changes in prostanoid metabolism. This site-dependent degree of injury may be associated with a local cyclo-oxygenase inhibition.

Beta(beta)3-adrenergic receptors in human pancreatic islet and duodenal somatostatin neuroendocrine cells.

BACKGROUND: We previously localized beta3-adrenergic receptors immunohistochemically in human gastrointestinal smooth muscle and incidently found a population of human pancreatic islet cells and duodenal epithelial neuroendocrine cells that also expressed beta3-adrenergic receptors. AIM: To identify the nature of the islet and duodenal cells that stained positive for beta3-adrenergic receptors. METHODS: Paraffin sections of human pancreas and duodenum and Chinese hamster ovary cells transfected with the human beta3-adrenergic receptor were immuno-stained for beta3-adrenergic receptors using an affinity-purified rabbit polyclonal antibody (anti-P12) raised against a 15 amino acid sequence (P12) of the human receptor. Immunohistochemical staining for the receptor was carried out in the presence and absence of P12 peptide and both somatostatin 14 and 18 peptides. beta3-adrenergic receptor-stained sections were also double-immunostained with anti-insulin, -glucagon, -somatostatin and -pancreatic polypeptide antibodies. RESULTS: A subpopulation of human pancreatic islet cells and duodenal epithelial cells expressed positive cytoplasmic beta3-adrenergic receptor immunostaining. Using distribution and double-staining techniques, these cells were found to be somatostatin-positive D cells but not A or B cells. The positive staining of D cells with anti-P12 antibody was inhibited by prior incubation of the antibody with P12 peptide but not somatostatin-14 or -28 peptides. Pancreatic vascular smooth muscle and duodenal vascular and non-vascular smooth muscle also stained with anti-P12 antibody. Transfected Chinese hamster ovary cells showed positive membrane staining. CONCLUSION: We have identified a population of neuroendocrine cells in the human pancreas and duodenum that express beta3-adrenergic receptors. These cells appear to be somatostatin D cells.

Review article: the concept of entero-colonic encephalopathy, autism and opioid receptor ligands.

There is growing awareness that primary gastrointestinal pathology may play an important role in the inception and clinical expression of some childhood developmental disorders, including autism. In addition to frequent gastrointestinal symptoms, children with autism often manifest complex biochemical and immunological abnormalities. The gut-brain axis is central to certain encephalopathies of extra-cranial origin, hepatic encephalopathy being the best characterized. Commonalities in the clinical characteristics of hepatic encephalopathy and a form of autism associated with developmental regression in an apparently previously normal child, accompanied by immune-mediated gastrointestinal pathology, have led to the proposal that there may be analogous mechanisms of toxic encephalopathy in patients with liver failure and some children with autism. Aberrations in opioid biochemistry are common to these two conditions, and there is evidence that opioid peptides may mediate certain aspects of the respective syndromes. The generation of plausible and testable hypotheses in this area may help to identify new treatment options in encephalopathies of extra-cranial origin. Therapeutic targets for this autistic phenotype may include: modification of diet and entero-colonic microbial milieu in order to reduce toxin substrates, improve nutritional status and modify mucosal immunity; anti-inflammatory/immunomodulatory therapy; and specific treatment of dysmotility, focusing, for example, on the pharmacology of local opioid activity in the gut.

Localization of the beta(beta)3-adrenoceptor in the human gastrointestinal tract: an immunohistochemical study.

BACKGROUND: Activation of human and non-human colonic beta(beta)3-adrenoceptors causes smooth muscle relaxation. beta3-Adrenoceptor agonists protect against experimental indomethacin-induced jejunal ulceration. The mechanism of protection may involve spasmolytic/vasodilatory agonist activity. The precise localization of beta3-adrenoceptors in the human gut is not known. AIM: To localize the beta3-adrenoceptor within the human gastrointestinal tract using the immunohistochemical technique. METHODS: Human beta3-adrenoceptors were immuno-localized in paraffin sections of human oesophagus (OS), stomach (ST), duodenum (DU), ileum (IL), sigmoid colon (SC), rectum (R) and gall-bladder (GB) using the rabbit polyclonal antibody anti-P12. Staining was graded , ++, + and 0. Immunostaining of SC was also done with pre-incubation of anti-P12 with P12 peptide. Western blotting of anti-P12 on human and murine IL and SC isolated membrane proteins was performed. RESULTS: All epithelia, vascular endothelial cells and ganglia scored 0. Smooth muscle of the vasculature, muscularis propria, muscularis mucosae and mucosa was graded, respectively, as follows; OS ( , , ,-), ST (++, , ++, ++), DU (++, , , +), IL (++, ++, ++, +), SC ( , ++, ++, ++), R (++, ++, +, +), GB ( , , -, 0). Pre-incubation of anti-P12 with P12 peptide almost abolished SC smooth muscle positivity. Western blot analysis using anti-P12 on human, but not murine, IL and SC membrane proteins revealed a single 5 5 kDa band, a size consistent with the predicted size of a partially glycosylated form of the human beta3-adrenoceptor. CONCLUSIONS: This immunohistochemical study has localized the beta3-adrenoceptor to vascular and nonvascular smooth muscle in the human gastrointestinal tract. These findings support a role for the beta3-adrenoceptor in the control of blood flow and motility in the human gastrointestinal tract.

Immunohistochemical study of vascular injury in acute multiple sclerosis.

AIMS: To examine the vascular changes occurring in three archival cases of acute multiple sclerosis, and to provide immunohistochemical evidence of early endothelial cell activation and vascular occlusion in this condition. METHODS: Central nervous system tissues from three cases of acute active multiple sclerosis and six non-inflammatory controls were stained using the following methods: haematoxylin and eosin, Luxol fast blue, cresyl violet, Bielschowsky's silver, and reticulin. Tissues were also immunostained with specific antibodies against collagen type IV, factor XIIIa, class II antigens, glial fibrillary acidic protein, and fibrinogen. RESULTS: Early vascular endothelial cell activation which may progress to vasculitis and vascular occlusion including class II antigen expression and fibrin deposition were identified. The vascular changes were seen prior to cerebral parenchymal reaction and demyelination, and were not seen in control cerebral tissues. CONCLUSION: It is proposed that vascular endothelial cell activation may be an early and pivotal event in the evolution of multiple sclerosis, and that demyelination may have an ischaemic basis in this condition. The vascular endothelium may contain an early element in the evolution of multiple sclerosis.

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.

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.

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.

Immunohistochemical study of tissue factor expression in normal intestine and idiopathic inflammatory bowel disease.

AIMS: To investigate the localisation of tissue factor expression in normal and inflamed intestine. METHODS: Serial cryostat sections of tissue taken from patients with Crohn's disease (n = 8), ulcerative colitis (n = 5), and from controls (n = 5) were stained with haematoxylin and eosin and immunostained for tissue factor, collagen type IV, fibrinogen and platelet glycoprotein IIIa. RESULTS: In control tissues tissue factor was present as a continuous layer along the epithelial basal lamina: sections from controls did not immunostain for fibrinogen or platelets. In non-ulcerated inflamed mucosa, tissue factor staining intensified in cases of Crohn's disease and was associated with fibrin deposition. Staining for tissue factor was either patchy or absent in cases of ulcerative colitis and there was no fibrin deposition. This change accompanied the early destruction of the epithelial basal lamina in ulcerative colitis that was not seen in Crohn's disease. In both diseases tissue factor expression in severely inflamed and ulcerated mucosa was present on lamina propria macrophages and vascular endothelium and was associated with fibrin or platelet thrombi. In three of eight cases of Crohn's disease tissue factor expression and thrombi were evident in areas of submucosal vasculitis. These were not seen in adjacent normal vessels. CONCLUSIONS: These observations are consistent with a tissue factor haemostatic barrier in the intestine: this barrier seems to be incomplete or defective in ulcerative colitis. Tissue factor expression by macrophages and endothelial cells may be important, particularly in the microvascular thrombosis and induration which are characteristic of Crohn's disease.

Direct in situ reverse transcriptase polymerase chain reaction for detection of measles virus.

New methods are described for combined intracellular reverse transcription (RT) and polymerase chain reaction (PCR) using single primer pairs, with direct incorporation of digoxigenin-11-dUTP into amplificants (direct in situ RT/PCR). Routinely used fixatives and minimal pre-treatments were employed. Target sequences of measles virus nucleocapsid (N) and phosphoprotein genes were detected within measles virus infected Vero cells, both in suspension and in formalin-fixed sections, that had been treated by in situ reverse transcription and 30 cycles of direct in situ PCR. Uninfected cells, omission of Taq polymerase, and irrelevant primers were used as controls. Distribution of measles virus within infected cells was determined by in situ hybridisation and immunocytochemistry for measles virus N gene and protein, respectively. Confirmation of amplification within sections was by gel electrophoresis, Southern blotting and sequencing of extracted amplicons. In the majority of cases, measles-infected cells exhibited intense cytoplasmic signal after direct in situ PCR; this was not seen in uninfected cells or infected cells reacted either with irrelevant primers or without Taq polymerase. Unfixed cells in suspension required nested reaction. Measles-specific in situ hybridisation and immunocytochemistry gave an identical signal distribution in sections. Nuclear artifact occurred in some sections and was unpredictable, although it was greatest either in areas of cellular damage, following DNase predigestion, or with vigorous protease pre-treatment. In situ RT-PCR is feasible for measles virus in acutely infected cells both in sections and in suspension. Further work is required to improve the procedure and to eliminate artefactual nuclear signal.

Perinatal and childhood risk factors for inflammatory bowel disease: a case-control study.

OBJECTIVE: To determine whether exposure to a measles epidemic in utero or in infancy is a risk factor for the development of Crohn's disease, and to determine whether such an association can be found in individuals with subacute sclerosing panencephalitis (SSPE), a condition in which early infection with measles is known to be of aetiological importance. METHODS: A postal questionnaire was sent to 16,875 members of two national inflammatory bowel disease patient support groups. A control group was composed of friends or neighbours. Birth data were compared with the dates of measles epidemics and six possible periods of susceptibility were examined. Birth data from a national register of patients with SSPE were analysed similarly. Previously identified risk factors were also examined. RESULTS: The answers from 2522 members and 2379 controls were analysed. We found no evidence of an association between the development of Crohn's disease and exposure to a measles epidemic. The birth dates of both groups were distributed normally throughout the year. No other early risk factor for the development of inflammatory bowel disease was detected. Exposure to a measles epidemic before the age of 1 year did not emerge as a risk factor for SSPE. CONCLUSION: These data contradict reports from a recent study in central Sweden, but relatively early exposure to measles in childhood may still be a risk factor for the development of Crohn's disease.