Effects of ranitidine 150 mg four times a day on 24-hour intragastric acidity and 24-hour plasma gastrin concentration

Twenty-four-hour integrated intragastric acidity and 24-hr integrated plasma gastrin concentration was measured twice in 23 healthy male volunteers on the seventh day of oral dosing with placebo or ranitidine 150 mg four times a day. The study was a randomized, double-blind, placebo-controlled, two-way crossover investigation. The mean integrated 24-hr intragastric acidity during dosing with ranitidine 150 mg four times a day decreased to 32% of the placebo value (placebo 825 mmol/hr/liter; ranitidine 265 mmol/hr/liter). The mean integrated 24-hr plasma gastrin concentration during dosing with ranitidine 150 mg four times a day was 904 pmol/hr/liter compared with placebo (410 pmol/hr/liter)--an increase of 122%. The median number of hours of pH > 3 during dosing with placebo and with ranitidine 150 mg four times a day were 5 and 11 hr, respectively. Ranitidine 150 mg four times a day caused a significant decrease of mean integrated intragastric acidity for each meal-related interval and also during the night.

Evaluation of the polymerase chain reaction for detecting the urease C gene of Helicobacter pylori in gastric biopsy samples and dental plaque

A polymerase chain reaction (PCR) assay with oligonucleotide primers homologous to a portion of the urease C gene of Helicobacter pylori was evaluated for specificity with pure DNA and biopsy material. The assay was used to test for the presence of the organism in dental plaque. The species specificity of detection was confirmed by ensuring that the primers did not amplify DNA extracts from H. cinaedi, H. felis, H. fennelliae, H. mustelae and H. nemestrinae. Sixty-two gastric biopsy samples collected from 14 patients (antrum, body and duodenal sites) were cultured and PCR was performed on the samples after culture. Primer sites were conserved in genomically diverse strains. Samples prepared by single-step heat lysis of bacterial cells and biopsy material did not inhibit PCR. The overall specificity was 96% irrespective of genotype. H. pylori was not cultured from dental plaque (15 patients), neither was H. pylori DNA detected by PCR in either urea breath test-positive or -negative individuals. The results showed that primer pair sequences within the urease C gene are conserved in most strains and provide an accurate basis for detecting H. pylori. As the PCR assay was not inhibited and did not yield false positive results with crude extracts from organisms or in the presence of biopsy material, its value as a diagnostic test was confirmed.

Audit of endoscopic surveillance biopsy specimens in HIV positive patients with gastrointestinal symptoms

An audit of upper gastrointestinal endoscopy in HIV infected patients with gastrointestinal symptoms assessed the frequency of disease detected by endoscopy and routine laboratory analysis of surveillance biopsy specimens. Sixty nine consecutive endoscopies were performed in 59 HIV infected patients. Endoscopic biopsy specimens were taken from the lower oesophagus, gastric antrum, and third part of the duodenum for virology, histopathology, parasitology, bacteriology, and mycobacterial culture. Endoscopic appearances detected disease in 25/59 (42.4%) patients (oesophageal candida, 14; oesophageal ulcer, 3; Kaposi's sarcoma, 4; others, 4), but only 4/43 (9.3%) specimens showed evidence of disease in the absence of endoscopic abnormality. Virology for cytomegalovirus (detection of early antigenic fluorescent foci and culture) was positive in 6/59 (10.2%) patients, but parasitology and mycobacterial culture were negative in all cases. Histopathology was abnormal in 11/52 (21%) oesophageal biopsy specimens, 13/47 (28%) gastric biopsy specimens, and 4/65 (6%) duodenal biopsy specimens. Abnormal findings were found predominantly in those with advanced HIV disease (CDC Stage IV) (21/33 patients (64%)) compared with those with early HIV disease (CDC Stage II) (5/26 (19%)). In conclusion, upper gastrointestinal endoscopy detects macroscopic disease in AIDS patients and those with low CD4 counts, but routine surveillance biopsy specimens of apparently normal bowel in early HIV disease (or where CD4 counts are greater than 0.2 x 10(9)/1) are of little value.

Gastric secretion and peptic ulceration in cirrhosis

Stomach function and secretions are altered significantly in patients with cirrhosis, both with or without portal hypertension. This review covers the abnormalities of gastric acid and pepsin secretion, and gastrin release. Histological and endoscopic changes, and the impaired cytoprotection associated with cirrhosis, are discussed in the context of abnormal gastric secretion. In addition, the symptomatology and association of H. pylori, and treatment of duodenal ulceration in cirrhosis are discussed. It is clear from this review that additional studies are needed to further understand gastric function in cirrhotic patients.

Intestinal permeability and function in patients infected with human immunodeficiency virus. A comparison with coeliac disease

The relationships among intestinal permeability, advancing human immunodeficiency virus (HIV) infection, and the presence of diarrhoea or weight loss were investigated in 51 HIV patients and 20 healthy controls. Ten patients with untreated coeliac disease were also investigated for comparison. Fasting subjects drank an isosmolar test solution containing D-xylose, lactulose (LL), L-rhamnose (R) and 3-O-methyl-D-glucose. Urine was collected for 5 h, test sugar content being subsequently measured by thin-layer chromatography for the dosing sugars. Intestinal permeability (LL/R excretion ratio) and recovery of D-xylose and 3-O-methyl-D-glucose in urine were abnormal in patients with HIV disease, and especially those with diarrhoea, as they were in coeliac disease. Patients with coeliac disease and HIV disease, especially when diarrhoea and/or weight loss were present, had significantly reduced 5-h excretion of L-rhamnose, D-xylose, and 3-O-methyl-D-glucose. These data indicate that abnormal permeability and reduced intestinal absorption capacity are common in HIV patients, occur at all stages of HIV disease, especially in the presence of diarrhoea, and, with the exception of lactulose permeation, are relatively similar to the alterations seen in coeliac disease.

Short report: the absorption of fluconazole and itraconazole under conditions of low intragastric acidity

The study investigated the oral absorption of two antifungal agents, fluconazole and itraconazole, under conditions of low intragastric acidity. Twelve healthy male volunteers received each of 4 dosing regimens: 200 mg itraconazole alone, 200 mg itraconazole and famotidine, 100 mg fluconazole alone, and 100 mg fluconazole and famotidine. Two oral doses of 40 mg famotidine were used to induce hypochlorhydria. Serum drug concentrations were measured (by high pressure liquid chromatography) for 48 h after a single dose of each anti-fungal agent. When dosed with famotidine, there was a significant 52.9% decrease of the peak intraconazole concentration (P < 0.011), and a significant 51.1% decrease of the 48-h integrated serum intraconazole concentration (P = 0.005). Famotidine-induced hypochlorhydria did not affect the absorption of fluconazole.

Evidence of persistent measles virus infection in Crohn's disease

Transmission electron microscopy was used to examine the microvasculature of perfusion-fixed tissues from Crohn's disease and control patients. Paramyxovirus-like particles, and inclusions consisting of condensations of nucleocapsid, in giant cells and endothelium at foci of vascular injury were identified in all 9 Crohn's disease patients. Tissues from patients with Crohn's disease were also examined by either in situ hybridisation (n = 10) or immunohistochemistry (n = 15), and compared to inflammatory and noninflammatory controls (n = 22). Hybridisation for measles virus N-protein genomic RNA was positive in all cases of Crohn's disease localising to foci of granulomatous vasculitis and lymphoid follicles. Positive immunohistochemical staining for measles virus nucleocapsid protein was positive in 13 of 15 patients with Crohn's disease, localising to foci of granulomatous inflammation. Hybridisation for measles virus RNA was positive in a minority of control intestinal tissues; viral inclusions were not seen ultrastructurally. Immunostaining was negative in control cases of intestinal tuberculosis. These observations suggest that measles virus is capable of causing persistent infection of the intestine and that Crohn's disease may be caused by a granulomatous vasculitis in response to this virus.

Gastric acid secretion and intragastric acidity: measurement in health and disease

Gastric acid secretion tests have limited use in clinical practice. For practical purposes, a pH measurement on a fasting gastric aspirate will provide strong evidence of the presence or absence of achlorhydria. Tests of gastric acidity, in particular 24-h acidity studies, have provided considerable insight into normal and abnormal gastric physiology, and have largely determined the dosing regimens for the management of acid-peptic diseases. Acid tests may be simple to perform, so much so that they have been suggested as 'practicals' for student teaching (Nicol et al, 1991). However, reproducible and meaningful results require careful attention to detail, and the appropriate mathematical analysis is still subject to some debate. It is important that the presentation of the data should allow the reader to assess the response over the 24-h period, and also the range of individual responses. Despite the many years of research into gastric acid secretion, only recently have the effects of age, sex, diet, smoking and mental stress been identified. In addition, many data need to be reviewed in the light of the effects of H. pylori infection on gastrin release. H2-receptor antagonists had been studied extensively before and since their first clinical use in 1974, but surprisingly only recently have the issues of tolerance and rebound been defined. The 24-h intragastric acidity profile remains an essential study before the start of clinical trials on any new drug to be used for the treatment of acid-peptic diseases.

Effect of ranitidine bismuth citrate on postprandial plasma gastrin and pepsinogens

Ranitidine bismuth citrate was compared with an equipotent dose of ranitidine, to determine whether the former, by an anti-Helicobacter pylori activity, would counteract the rise of gastrin resulting from ranitidine's gastric acid antisecretory activity. Twenty four men with duodenal ulcers were studied before and on the 8th day of dosing with either ranitidine bismuth citrate 800 mg twice daily or ranitidine 300 mg twice daily (double blind, randomised, parallel groups). Fasting and postprandial plasma gastrin and plasma pepsinogen I and II concentrations were measured, and a 13C-urea breath test was performed before and on the 8th day of dosing. The 13C-urea breath tests were positive in 21 patients before dosing and remained positive in nine of nine of the ranitidine dosed patients, whereas only two of 12 patients treated with ranitidine bismuth citrate remained positive. The expected rise in meal stimulated plasma gastrin with ranitidine was seen in the 12 patients who received ranitidine but, despite suppression of H pylori urease activity in 10 of 12 patients taking ranitidine bismuth citrate, there was no attenuation of the meal stimulated gastrin rise. There was no significant difference in the mean derived (4 hour) plasma pepsinogen I and II concentrations after dosing with ranitidine or ranitidine bismuth citrate.

Early mucosal changes in Crohn's disease

Aphthoid ulceration has been regarded as an early macroscopic feature of Crohn's disease, yet the cause of this mucosal lesion is unknown. Examination of areas of apparently normal and non-inflamed bowel in Crohn's disease has allowed the identification of mucosal changes which occur before macroscopic and microscopic ulceration. Thirty five resection specimens from patients with Crohn's disease were compared with 12 specimens from patients with ulcerative colitis and 13 controls. Specimens were fixed either by immersion in formalin in the routine way or by perfusion fixation with formalin at mean arterial pressure. Immunostaining for macrophages, vessel wall, and blood constituents allowed identification of small mucosal capillaries which were not apparent otherwise. In Crohn's disease damage and rupture of these small capillaries occurred before infiltration of the lamina propria by inflammatory cells. Loss of the overlying epithelium seemed to follow this vascular damage.

Ranitidine has no effect on postbreakfast ethanol absorption

The effect of ranitidine, the H2-receptor antagonist, on the systemic bioavailability of ethanol (0.3 g/kg body weight) taken orally 1 h after breakfast, was investigated in a randomized, placebo-controlled, double-blind cross-over study. Twenty normal male subjects (age, 19-26 yr) were studied on the morning of the 8th day of twice-daily dosing with either 150 mg ranitidine or placebo. Plasma ethanol concentration was measured by the alcohol dehydrogenase method from 0 to 240 min after oral ingestion of ethanol (100% ethanol made up to 200 ml orange juice). Compared with placebo, dosing with ranitidine resulted in nonsignificant changes in either the mean integrated 4-h plasma ethanol concentration (27.8 vs. 32.4 mg.h/dl), the peak plasma ethanol concentration (18.0 vs. 21.1 mg/dl), or the time to peak (43 vs. 40 min). There is no clinically important interaction between ranitidine and a low dose of ethanol taken orally 1 h after breakfast.

Early histological features of small intestinal injury induced by indomethacin

The early histological features of indomethacin-induced jejunal injury in the rat are described in tissues preserved by perfusion-fixation with 10% formol-saline. After an oral dose of indomethacin (15 mg/kg, known to cause severe multifocal ulceration of the rat jejunum), groups of rats were anaesthetized with subsequent perfusion-fixation of the gastrointestinal tract at 1, 2, 3, 6 and 48 h after dosing. Using routine light microscopic techniques, we have observed a sequence of four distinct stages, in time, of small intestinal injury. The earliest histological features were shortening of the villi, epithelial stratification, basal lamina degeneration, eosinophil degranulation and infiltration of the epithelium prior to infiltration of the mucosa by neutrophils. We consider that these earliest changes, seen at 1, 2 and 3 h, represent a distinct histological entity termed Type 1 change or villous 'tufting'. Type 2 change includes all of the features of Type 1 change plus the subsequent infiltration of the mucosa by neutrophils at 2, 3 and 6 h. Type 3 change includes necrosis of the upper-third of the villi and was mainly seen at 3 and 6 h. Type 4 change describes extreme injury to more than one-third of the mucosa with severe, acute inflammation and perforation of the bowel wall by 48 h. Although a small number of neutrophils had appeared to infiltrate the mucosa as early as 2 h after dosing, they were only significantly increased at 3, 6 and 48 h. Possible pathogenic mechanisms involved in shortening of villi as a result of smooth muscle contraction and the role of mucosal eosinophils in NSAID-induced jejunal injury in the rat are discussed.

Crohn's disease and anastomotic recurrence: microvascular ischaemia and anastomotic healing in an animal model

Microvascular injury and ischaemia may be factors in anastomotic recurrence after resection for Crohn's disease. This hypothesis was explored in a ferret model of multifocal intestinal infarction. At laparotomy, isolated loops of small intestine were injected intraarterially with styrene microspheres (test loop) or saline (control). At a second laparotomy 72 h later, test and control loops were divided and an end-to-end anastomosis performed between test loops (n = 2), test and control loops (n = 9) or control loops (n = 2). Abnormalities including chronic transmural inflammation, ulceration and granuloma formation were identified 2 weeks after the second operation in ten of the 11 surviving animals; changes were confined to the test loops and were more prominent adjacent to the anastomosis. No abnormalities were seen in control loops. The combination of two self-limiting ischaemic insults can produce a pattern of intestinal inflammation similar to that seen in anastomotic recurrence in Crohn's disease.

Factor XIIIA subunit and Crohn's disease

Factor XIIIA is the active subunit of plasma factor XIII that is responsible for cross linking fibrin into a stable clot. Sixteen patients with Crohn's disease were studied prospectively from relapse (Crohn's disease activity index > 150) into remission. Plasma factor XIIIA concentrations were significantly lower in active disease (median 63 (95% CI 46-72) U/dl) than remission (median 90 (95% CI 60-112) U/dl; p = 0.002). Plasma factor XIIIA concentrations correlated positively with the activity index (p = 0.005) and platelet count (p = 0.003), and negatively with serum albumin (p = 0.006). In five patients with persistent aggressive disease, the factor XIIIA concentration remained below the lower range of normal despite apparent clinical improvement in response to medical treatment. Tissues from three patients who underwent surgical resection during the study were immunostained for factor XIIIA. Gut mucosal and submucosal macrophages stained strongly for factor XIIIA. In one patient, capillary thrombi near superficial mucosal erosions immunostained for factor XIIIA in macroscopically normal mucosa. Similar changes were identified in more severely inflamed sections of intestine from the other two patients. The demonstration of significantly low plasma factor XIIIA concentrations in active Crohn's disease, and the immunostaining of factor XIIIA in capillary thrombi in the bowel wall, suggest that activation of coagulation may be involved in the pathogenesis of Crohn's disease. The plasma factor XIIIA concentration may prove a useful laboratory marker of disease activity.

Evidence for activation of coagulation in Crohn's disease

Haemostatic changes in 16 patients with Crohn's disease were studied from active disease into clinical remission and beyond. Elevated concentrations of fibrinopeptide A (FpA) and prothrombin fragments F1 + 2 (F1 + 2) were found at times of both active (FpA median 3.2, range [0.3-40] ng/ml and F1 + 2 median 2.3, range [0.3-18] nm/l) and inactive disease (FpA median 2, range [0.4-40] ng/ml and F1 + 2 median 1.3, range [0.2-20) nm/l]. We also measured the physiological inhibitors of coagulation and fibrinolysis; there was no significant difference in the levels of antithrombin III, protein C or the Exner ratio between active and inactive disease. Free protein S levels were significantly lower in active disease (median 34, range 9-54 U/dl) than in remission (median 40, range 12-65 U/dl). Plasminogen activator inhibitor type 1 (PAI-1) was significantly raised in remission (median 11, range 3-32 ng/ml) when compared to active disease (median 7, range 3-42 ng/ml). The D-dimer correlated significantly with fibrinopeptide A (P < 0.001), suggesting reactive fibrinolysis in some patients. Most (35/52, 67%) samples showed evidence of persistent haemostatic activation (elevated FpA and/or F1 + 2) during phases of apparent clinical remission in Crohn's disease, a factor that is not reflected by clinical activity scores. This study supports the hypothesis that coagulation is activated in the mesenteric vasculature of patients with Crohn's disease.

Ranitidine, cimetidine, famotidine have no effect on post-prandial absorption of ethanol 0.8 g/kg taken after an evening meal

Forty-seven healthy male subjects were studied twice using a randomized, placebo-controlled design. Each subject took an 8-day course of two of the following four regimens; 300 mg ranitidine, 800 mg cimetidine, 40 mg famotidine or placebo (identical either to 300 mg ranitidine or 800 mg cimetidine). The systemic bioavailability of ethanol (integrated 6-h plasma ethanol concentration, peak plasma ethanol concentration, and the time to peak plasma ethanol concentration) was measured after the oral ingestion of 0.8 g of ethanol per kg body weight, given one hour after an evening meal on Day 8 of each regimen. There was no significant difference of integrated 6-h plasma ethanol concentration, peak ethanol concentration, or time to reach peak ethanol concentration after dosing with either ranitidine, cimetidine or famotidine or placebo.

DNA fingerprints of Helicobacter pylori before and after treatment with omeprazole

AIMS

To test whether a hypoacidic environment may potentially "stress" Helicobacter pylori DNA, encouraging the emergence of strain variation.

METHODS

This hypothesis was tested by inducing prolonged hypoacidity with omeprazole, a potent antisecretory drug. The genomic DNA of H pylori was studied by electrophoretic separation of restriction endonuclease fragments followed by rRNA gene hybridisation in seven patients infected with H pylori before and after treatment with omeprazole 20-40 mg daily for six to eight weeks. DNA was isolated and purified using the guanidium thiocyanate reagent method. DNA samples were digested with Hae III, electrophoresed, vacublotted, and hybridised using a biotinylated cDNA probe prepared from 16S and 23S rRNA from H pylori NCTC 11638. Isolates were compared using their ribopatterns (DNA fingerprints).

RESULTS

A total of 26 isolates were obtained; all DNA isolates were cut by Hae III, which was the enzyme that gave the best resolved hybridisation patterns for analysis. No two patients harboured the same strain. The isolates from two patients showed evidence of subtypic variation; one patient had two distinct strains and four patients had their own indistinguishable strains before and after treatment with omeprazole. For each patient, the paired ribopatterns of H pylori DNA were not affected by treatment with omeprazole for six to eight weeks.

CONCLUSION

The H pylori genome is relatively stable when exposed to the conditions of prolonged hypoacidity that result from treatment with omeprazole.

Detection of herpesvirus DNA in the large intestine of patients with ulcerative colitis and Crohn's disease using the nested polymerase chain reaction

The prevalence of herpesvirus DNA was examined in inflammatory bowel disease tissue. DNA was extracted from resection and biopsy specimens of the large intestine from patients with ulcerative colitis (n = 21), patients with Crohn's disease (n = 29), and patients with noninflammatory bowel disease (controls) (n = 21). The nested polymerase chain reaction was used to detect viral DNA using primer pairs specific for either cytomegalovirus (CMV), herpes simplex virus 1 (HSV1), human herpesvirus 6 (HHV6), varicella zoster virus (VZV), or Epstein Barr virus (EBV). HSV1 and VZV DNA were not detected in any of tissue samples. There was a high prevalence of CMV (81%), HHV6 (76%), and EBV (76%) DNA in ulcerative colitis tissue compared to Crohn's disease tissues (CMV 66%, HHV6 45%, EBV 55%). Control tissue had a relatively low frequency of CMV (29%) and EBV (19%) DNA but a prevalence of HHV6 DNA similar to that of ulcerative colitis (86%). However, the simultaneous presence of HHV6 and CMV and/or EBV DNA in ulcerative colitis tissue (76%) was much greater than in either Crohn's disease tissues (38%) or control tissue (29%) (P < 0.05). There was a low prevalence of CMV, HHV6, and EBV DNA in peripheral blood mononuclear cells from all patient groups. CMV and EBV are capable of reactivating HHV6: the high prevalence of coexistent HHV6 infection with either or both of these two viruses in ulcerative colitis tissue suggests that they may play a synergistic role in the pathogenesis of this disease.

Mucosal capillary thrombi in rectal biopsies

We studied the initial rectal biopsy from 46 patients in whom subsequent follow-up established the diagnosis of either self-limited colitis or inflammatory bowel disease. An additional 12 non-inflamed rectal biopsies were also studied. There was between 2 and 8 years of follow-up in each of these cases. Staining for fibrin (MSB, fibrinogen), platelets (factor XIIIA, Y2/51), and capillary basement membrane (reticulin, collagen 4) was performed to identify thrombotic material within capillaries. Mucosal capillary thrombi were best identified by staining for factor XIIIA; thrombi were observed in 8/13 cases of ulcerative colitis, 4/10 cases of Crohn's disease, 1/3 cases of unspecified inflammatory bowel disease and 5/20 cases of self-limited colitis. The presence of capillary thrombi was not related to the severity of inflammation, but none of the control biopsies showed capillary thrombi. Their presence seems of little diagnostic value in distinguishing inflammatory bowel disease from self-limited colitis. The pathogenetic significance of these mucosal capillary thrombi is uncertain.

The long-term management of duodenal ulceration using an H2-antagonist: symptomatic self-care compared with maintenance treatment

In a 48-week study of 319 duodenal ulcer patients, symptomatic self-care with an histamine H2-receptor antagonist (flexible self-chosen dosing with cimetidine 0, 400 or 800 mg/day) was compared with maintenance treatment (cimetidine 400 mg nocte). The rate of withdrawal from the study was similar in both groups. The mean consumption of cimetidine 400 mg tablets was significantly higher in the maintenance group (7.2 vs. 5.4 tablets/week; P less than 0.0001), but the mean cumulative number of days with ulcer symptoms was higher in the symptomatic self-care group (47.2 vs. 29.1 days in 48 weeks). The estimated number of days of work-loss due to ulcer symptoms was similar in both groups (approximately 4 days in the 48 weeks of observation). It is concluded that symptomatic self-care using an H2-antagonist can provide not only an economic but also an effective strategy for the long-term management of uncomplicated duodenal ulceration.

Short report: twenty-four-hour hyperpepsinogenaemia in Helicobacter pylori-positive subjects is abolished by eradication of the infection

Twenty-four-hour plasma pepsinogen I and II concentrations were determined in 8 healthy subjects with antibody to Helicobacter pylori, before and after treatment with tripotassium dicitrato bismuthate, amoxycillin and metronidazole, Therapy was successful in the 5 subjects with active H. pylori infection. In these subjects, median integrated 24-h plasma pepsinogen I and II concentrations significantly decreased from 2288 and 357 micrograms.h/L before treatment, respectively, to 1811 and 171 micrograms.h/L at 4-6 weeks after treatment, and 1643 and 150 micrograms.h/L at 20-24 weeks. By contrast, in the 3 subjects without evidence of active H. pylori infection, pre-treatment plasma pepsinogen I and II concentrations were similar to values found in the H. pylori-infected subjects after successful therapy, and they did not change significantly in response to therapy. H. pylori infection is associated with reversible hyperpepsinogenaemia.

A ferret model of acute multifocal gastrointestinal infarction

Based on the demonstration of mural granulomatous vasculitis in Crohn's disease, it was hypothesized that this vasculitis may account for the discontinuous pattern of lesions in this condition. Accordingly, the present study investigated the histological changes produced by interruption of the submucosal and mucosal microcirculation in the ferret midgut. Two techniques were used. First, up to 30 adjacent vasa recta were ligated using microsurgical techniques; this produced no evidence of ischemic damage. Second, interruption of the submucosal collateral plexus by the intra-arterial injection of styrene microspheres (27-, 50-, or 90-microns diameter) produced acute intestinal mucosal damage. A combination of 27- and 90-microns spheres resulted in focal mucosal inflammation, necrosis, and ulceration. "Summit" lesions with normal adjacent mucosa were observed 48 hours after embolization, with evidence of regeneration of the mucosa overlying the occluded vessels at 72 hours. This model shows that focal gastrointestinal infarction with normal adjacent mucosa can be produced by acute occlusion of submucosal and mucosal arteries.

Neuroendocrine changes in rat stomach during experimental diabetes mellitus

The effects of 48 days of streptozotocin-induced diabetes mellitus in rats on plasma concentrations of gastrin, somatostatin, pancreatic glucagon, and enteroglucagon have been assessed. In addition, neuroendocrine changes in sections of gastric mucosa were quantified using a computer-assisted morphometric system following immunohistochemical staining with polyclonal antibodies directed against gastrin, PGP 9.5 (a neural protein), and somatostatin. Diabetes resulted in significantly increased fasting plasma concentrations of somatostatin, and entero- and pancreatic glucagon. In contrast, lower plasma gastrin concentrations and decreased antral G-cell density were noted in diabetic rats. Gastric somatostatin and neuronal PGP 9.5 stain densities were unaltered by diabetes. Stomachs of diabetic rats weighed less, but both the jejunum and ileum showed evidence of mucosal hyperplasia. The gastric neuroendocrine atrophy observed in diabetes may be a consequence of elevated plasma somatostatin derived from nongastric sources. The enhanced growth of the intestinal mucosa may be related, directly or indirectly, to raised intraluminal glucose concentration in diabetes.

Gastric epithelial cell proliferation and histological damage after hypertonic sodium chloride: the effect of variation in the strain of rat

Two strains of rat, Sprague-Dawley and inbred Piebald Virol Glaxo pigmented (PVG) strain, were dosed orally with hypertonic sodium chloride at a dose of 0.25, 0.5, 1.0 or 1.33 g/kg. Gastric epithelial cell proliferation was compared 16 hours after a single dose. The rats were given intraperitoneal bromodeoxyuridine (20 mg/kg) 1 hour before sacrifice, and cells undergoing DNA synthesis (S-phase) were assessed using a monoclonal antibody to bromodeoxyuridine. The number of labelled cells per gastric gland was counted using video image analysis, assessing ten low-power fields (160-180 gastric glands) per rat. Tissue injury was graded for submucosal oedema, inflammation and necrosis; it was minimal after dosing with 0.25 and 0.5 g/kg of sodium chloride. The PVG rats were more susceptible to tissue injury after dosing with 1.0 or 1.33 g/kg of sodium chloride: submucosal oedema, 80% in the PVG and 10% in the Sprague-Dawley; inflammation, 70% compared with 10%; necrosis, 70% compared with 20%. The number of labelled cells per fundic gland increased with increasing dose concentration of sodium chloride and the response was similar for both strains of rat. Plasma gastrin concentration at the time of sacrifice was significantly higher in the PVG rat for the 0.5, 1.0 and 1.33 g/kg doses. These strain differences may be useful in the further evaluation of the mechanisms of sodium chloride-induced tissue damage and repair.