Cytomegalovirus infection of the human gastrointestinal tract.

BACKGROUND: Current interest in cytomegalovirus (CMV) is largely due to an increase in the number of cases of acquired immunodeficiency syndrome and organ transplantation in recent years. The proper recognition of CMV-infected cells in gastrointestinal mucosal biopsies is critical for effective treatment of this condition. METHODS: A total of 6580 endoscopic mucosal biopsies from 6323 patients in the 8-year period (1989-1996) were examined for CMV inclusion bodies. The endoscopic appearance and particularly the presence of ulcers were also analysed. RESULTS AND CONCLUSIONS: The prevalence of cytomegalovirus (CMV) inclusions was 9 per thousand in the gastrointestinal mucosal biopsies from an unselected group of patients. Of the 54 patients with CMV infection, 37 were immunocompromised and 17 apparently immunocompetent. Typical Cowdry inclusions and atypical inclusions were present, the latter more frequently in immunocompromised patients. The maximum prevalence of inclusions was in the oesophageal mucosa in immunocompromised individuals.

Endoscopic mucosal biopsies are useful in distinguishing granulomatous colitis due to Crohn's disease from tuberculosis.

BACKGROUND: Intestinal tuberculosis and Crohn's disease are chronic granulomatous disorders that are difficult to differentiate histologically. AIMS: To characterise distinctive diagnostic features of tuberculosis and Crohn's disease in mucosal biopsy specimens obtained at colonoscopy. METHODS: Selected histological parameters were evaluated retrospectively in a total of 61 biopsy sites from 20 patients with tuberculosis and 112 biopsy sites from 20 patients with Crohn's disease. The patients were chosen on the basis of clinical history, colonoscopic findings, diagnostic histology, and response to treatment. RESULTS: The histological parameters characteristic of tuberculosis were multiple (mean number of granulomas per section: 5.35), large (mean widest diameter: 193 microm), confluent granulomas often with caseating necrosis. Other features were ulcers lined by conglomerate epithelioid histiocytes and disproportionate submucosal inflammation. The features characteristic of Crohn's disease were infrequent (mean number of granulomas per section: 0.75), small (mean widest diameter: 95 microm) granulomas, microgranulomas (defined as poorly organised collections of epithelioid histiocytes), focally enhanced colitis, and a high prevalence of chronic inflammation, even in endoscopically normal appearing areas. CONCLUSIONS: The type and frequency of granulomas, presence or absence of ulcers lined by epithelioid histiocytes and microgranulomas, and the distribution of chronic inflammation have been identified as histological parameters that can be used to differentiate tuberculosis and Crohn's disease in mucosal biopsy specimens obtained at colonoscopy.

Eosinophilic gastroenteritis--an Indian experience.

Eosinophilic gastroenteritis is an uncommon disorder with varied presentation. Records of 7 patients (6 men) with eosinophilic gastroenteritis, presenting to a large referral hospital over a 10-year period, were analyzed. The patients were young adults (mean age 32 years) with short duration (median 2 months) of illness. Symptoms included abdominal pain and vomiting (100%), weight loss (57%), diarrhea (43%) and abdominal distension (43%). Peripheral eosinophilia was present in all the patients. The diagnosis was made at duodenal (2 patients) or cecal (1) biopsy or surgical full-thickness jejunal biopsy (4). Three patients had predominantly mucosal disease (Klein type I), whereas two patients each had predominantly muscular (type II) and submucosal (type III) disease. Surgical resection was curative in one patient with type II disease. The other six responded to prednisolone, with complete resolution in one patient.

Salicylate inhibits fimbriae mediated HEp-2 cell adherence of and haemagglutination by enteroaggregative Escherichia coli.

Enteroaggregative Escherichia coli (EAggEC) are associated with both acute and persistent diarrhoea in children. Bowel colonisation due to fimbrial adherence factors appears to play a major role in the disease process. In this study, we investigated the effect of sodium salicylate and 5-aminosalicylic acid on adherence of a type strain and 40 clinical isolates of EAggEC to HEp-2 cells and erythrocytes from different species. Growth in the presence of 10 mM salicylate resulted in markedly decreased adherence to tissue culture cells with 33/40 (82.5%) isolates, and was also associated with inhibition of haemagglutination in 20/33 (60.6%) isolates. Complete or partial inhibition of adherence was also seen in two of five isolates showing localised adherence and three of five isolates with diffuse adherence. Decrease in adherence was associated with decreased or absent expression of fimbriae in 28/40 (70%) of the EAggEC isolates, although production of outer membrane proteins was not affected. Salicylates appear to inhibit adherence mediated by fimbrial adhesins.

Immunoproliferative small intestinal disease in South India: a clinical and immunomorphological study.

Immunoproliferative small intestinal disease (IPSID), a proliferative disorder affecting the intestinal immune system, has only been reported sporadically in India. Fifteen patients with malabsorption syndrome who were diagnosed to have IPSID were included in this study. Mucosal biopsies from all patients, full thickness surgical biopsies from 10 and autopsy material from four patients were examined by light microscopy and immunohistochemistry. The patients were predominantly young (aged 16-36 years) and male (13 of 15). Diarrhoea, weight loss, vomiting and abdominal pain were the major symptoms. The upper small bowel was involved in all cases. Involvement of large bowel was detected antemortem in three patients, but was found in all autopsied patients. Involvement of the stomach was noted in one patient at autopsy. Mesenteric lymph nodes were involved in all patients who underwent laparotomy. The plasmacytic infiltrate was uniformly positive for alpha-heavy chain, and either negative for light chain production or showed monotypic light chain production. Some of the blasts were also positive for alpha-heavy chain. Three patients died before therapy could be commenced. One patient with stage A disease is alive and clinically free of disease at 7 years. Of the remainder, there have been four long-term survivors with chemotherapy. Immunoproliferative small intestinal disease occurs in southern India and has characteristics similar to that in other parts of the world. Early diagnosis may improve outcome in this disease.

Ultrastructural changes in the upper small intestinal mucosa in patients with cholera.

BACKGROUND & AIMS: Small intestinal mucosal ultrastructural abnormalities were reported in a limited number of patients with cholera in the 1970s. This study extends these observations by examining distal duodenal biopsy samples from 19 patients with cholera and 10 controls. METHODS: Endoscopic biopsy samples obtained, usually during the first 24 hours of illness, were processed for electron microscopy. RESULTS: Widening of intercellular spaces and alteration of apical junctional complexes were prominent in the villus epithelium, whereas blebbing of microvillus border and mitochondrial changes were more prominent in the crypt epithelium. The apical junctional and intercellular space changes were not altered by oral rehydration. Degranulation of argentaffin cells, mucosal mast cells, and eosinophils; increase in neutrophil polymorphs; and changes in the enteric nerve fibers and microvasculature were also present. The extent of the changes correlated with clinical severity. CONCLUSIONS: The differential involvement of the villus and crypt suggests that factors responsible for secretion may act differentially on surface and crypt epithelium and that both regions may contribute to secretion. The contribution of the enteric nervous system, vasculature, argentaffin cells, mucosal mast cells, eosinophils, and neutrophils in the secretory process and in determining the severity of the clinical illness must be determined by further clinical studies.

Prevalence of Helicobacter pylori in southern Indian controls and patients with gastroduodenal disease.

The spiral organism Helicobacter pylori has been causally implicated in the genesis of various gastroduodenal diseases. Since these diseases are common in southern India, this study was undertaken to determine the prevalence of H. pylori in the gastric mucosa of asymptomatic adults and patients with various gastroduodenal diseases. H. pylori was detected in the gastric mucosa of 25 of 30 (83.3%) normal volunteers. Prevalence rates in the disease groups were also high, and included 38 of 41 patients with duodenal ulcer (92.6%), 13/16 with gastric ulcer (81.3%), and 85/119 subjects (71.4%) with non-ulcer dyspepsia. Light microscopic examination of the gastric mucosa provided the best method of detecting H. pylori. H. pylori colonization was significantly associated with histological abnormalities, mainly chronic atrophic gastritis (147) and superficial gastritis (11), while only three of 161 H. pylori positive patients had histologically normal antral mucosa. Ultrastructural examination revealed changes in the apical complex of the gastric mucosal cells in response to bacterial adhesion, with mucus depletion and cellular damage. Bacteria were also noted disrupting the tight junctions and entering the intercellular spaces. The high prevalence of H. pylori infection may explain the high incidence of gastritis, duodenal ulceration and gastric carcinoma in this population. However, in this population, the prevalence of infection in asymptomatic individuals was nearly as high as that in duodenal ulcer, underlining the need for further study to identify the differences in host response or bacterial pathogenicity that lead to the development of ulcer in only some individuals.

Alteration of colonic absorption by long-chain unsaturated fatty acids. Influence of hydroxylation and degree of unsaturation.

Unabsorbed dietary unsaturated fatty acids may cause diarrhea in patients with steatorrhea, but their ability to cause colonic fluid secretion is not known. The present study investigated the effect of several dietary long-chain unsaturated fatty acids on colonic absorption and morphology in the rat colon in vivo. The fatty acids tested induced concentration-dependent net water secretion. The ability of these fatty acids to induce net water secretion varied as follows: linolenic acid (18:3) > linoleic acid (18:2), ricinoleic acid (18:1 OH) > oleic acid (18:1), palmitoleic acid (16:1). Net absorption of sodium and chloride were decreased in fatty acid perfusions. Mucosal activity of sodium potassium adenosine triphosphate and adenyl cyclase were not significantly altered by fatty acids. Epithelial cell damage was noted and correlated with the ability of the fatty acid to induce fluid secretion. Unsaturated fatty acids induce epithelial cell damage and fluid secretion in the colon, their effect being related to the degree of unsaturation.

Interaction of melittin with endotoxic lipid A.

Several amphipathic and cationic substances are known to bind lipid A, the toxic component of bacterial lipopolysaccharides. In this report, we have characterized, by fluorescence methods, the interaction of melittin, an amphipathic and basic 26-residue polypeptide isolated from bee venom, with lipid A. The stoichiometry of the complex appears to be two molecules of melittin to one of lipid A with a dissociation constant of 2.5 x 10(-6) M. The binding of melittin not only modifies the endotoxic properties of lipid A in a number of biological assays, but also results in abrogation of the hemolytic activity of melittin. A model of the complex is proposed based on the known structures of lipid A and melittin, and the observed stoichiometry of binding.

Morphology of rectal mucosa of patients with shigellosis.

Biopsy specimens of rectal mucosa from 46 consecutive patients with dysentery, from whom shigellae were isolated, were examined. On examination it appeared that the specialized epithelial cells overlying lymphoid follicles were the first to be damaged, and subsequently a vascular lesion led to detachment of epithelial cells. The vascular lesion was widespread in the lamina propria mucosae. Extensive ulceration was associated with invasion of epithelial cells by the organism. There was marked depletion of mucus and an increase in mitotic activity in the crypts. Abscesses of the crypts were rare. The only difference between patients from whom the Shiga bacillus was isolated and patients from whom other shigellae were isolated was a higher prevalence of epithelial cell detachment and luminal exudate. In patients who had been ill for greater than 1 week, cell damage of the crypts was associated with cell-mediated cytolysis, a release of cytotoxic substances from eosinophils and mast cells, and relative vascular insufficiency, all of which may contribute to persistence of dysentery.

A combined TDDA-PVC pH and reference electrode for use in the upper small intestine.

Incorporation of a ligand into polyvinylchloride allows the production of ion selective electrodes that are soft-bodied and disposable. With features make them especially suitable for clinical, particularly gastroenterological, investigations. We report here on the construction of a combined reference and pH electrode suitable for use at jejunal biopsy. With this type of pH electrode, the pH of the mucosal surface of the jejunum in UK and in Indian subjects, without evidence of upper gastrointestinal disease, was about pH 6.0. This was almost identical to previous values measured using a separate reference electrode. Both the polymer electrode and a suitable data logger can be conveniently produced in the laboratory and compare favourably with commercially available systems, provided the range of pH likely to be encountered is within the operating range of the incorporated ligand.

Jejunal surface pH measurements in tropical sprue.

The mucosal surface pH of jejunal biopsy samples incubated in vitro in Krebs-phosphate buffer was measured. Biopsies from 7 healthy individuals or tropical sprue subjects in complete remission had a mean surface pH of 5.8 +/- 0.09, similar to values for normal Caucasian subjects living in the UK. The mean surface pH of biopsies from 20 sprue patients, 6.0 +/- 0.08, was significantly higher (P less than 0.05) than that of the control subjects. Sprue patients could be sub-divided into those with 2 or more abnormal results in 3 intestinal function tests, and those with one or no abnormal test. The 9 low scorers showed a mean surface pH of 5.75 +/- 0.06 resembling the control mean, whereas the 11 high scorers had a higher (P less than 0.01) mean surface pH of 6.17 +/- 0.08. Mucosal surface pH correlated directly with 3 d mean faecal fat excretion and inversely with xylose and vitamin B12 absorption values but not with the nutritional indicators serum albumen, folate or blood haemoglobin levels. As in coeliac disease, mucosal surface pH in the jejunum is elevated above normal in tropical sprue and may reflect the extent to which normal ion transport processes are affected.

Absorption of water and sodium and activity of adenosine triphosphatases in the rectal mucosa in tropical sprue.

In 10 southern Indian patients with tropical sprue, in vivo dialysis showed a defect of absorption of water and sodium from the rectum, when compared with 11 healthy volunteers. Sodium-potassium-ATPase activity, measured in homogenates of rectal biopsies, was significantly diminished in patients with sprue. Magnesium-ATPase and alkaline phosphatase were normal in biopsy homogenates. Decreased activity of colonic sodium-potassium-ATPase may contribute to diarrhoea in some patients with tropical sprue.

Epithelial cell renewal and turnover and relationship to morphologic abnormalities in jejunal mucosa in tropical sprue.

A morphometric study confirmed that increasing severity of the jejunal mucosal morphologic lesion is accompanied by increased crypt height and reduced villus length in patients with tropical sprue. Mitotic activity in the crypts was increased. Pulse labeling of jejunal mucosal biopsies cultured in vitro with [3H]thymidine confirmed that there was increased uptake of label in tropical sprue with more rapid migration of labeled cells to the villi. The label was also lost more rapidly. Earlier ultrastructural studies have shown enterocyte damage and extrusion in the crypt and villus epithelium. The present data suggest that in the jejunal mucosa of patients with tropical sprue, the loss of damaged enterocytes leads to villus shortening and increased cell production in the crypts, with hypertrophy of the crypts.

A comparison of the susceptibility of three human gut tumour-derived differentiated epithelial cell lines, primary monkey kidney cells and human rhabdomyosarcoma cell line to 66-prototype strains of human enteroviruses.

The growth of prototype strains of 31 serotypes of ECHO, 3 polio, 6 Coxsackie B, 24 Coxsackie A and enterovirus serotypes 70 and 71 were tested in parallel in primary monkey kidney cells (PMK), RD cells and three gut tumour-derived differentiated epithelial cell lines (HRT-18 HT-29 in SKCO-1). All 31 serotypes of ECHO viruses grew in HT-29, 27 and SKCO-1, 5 in HRT-18, 29 in PMK and 29 in RD. There was good growth of poliovirus serotypes in all five cell types. Coxsackie B viruses grew well in all the cell lines except RD. Fifteen of the Coxsackie A viruses grew in SKCO-1, 4 in HT-29, 3 in HRT-18 and 7 in RD. Enterovirus serotypes 70 and 71 grew only in RD cells after 3 serial passages. These results showed that 2 of the gut tumour-derived cell lines, HT-29 and SKCO-1 had a markedly wider susceptibility, with comparable or wider sensitivity, for enteroviruses, than PMK and RD. While their use for field isolation from clinical samples is not yet fully established HT-29 and SKCO-1 would appear to be ideal for a variety of laboratory manipulations of the majority of enteroviruses.

An epidemic of acute diarrhoea in rural southern India associated with echovirus type 11 infection.

An epidemic of diarrhoea with two distinct waves affected a village of 1375 people in southern India in 1983. The first wave of the epidemic, from the last week of December 1982, had a sharp peak in January 1983 and was over by March. Echovirus type 11 was isolated from patients, who also had a serum antibody response to the virus. During the second wave of the epidemic, from May to September 1983, the clinical features were different and Shigella flexneri was isolated without significant viral isolates. Infection during the first wave did not protect from the second wave. Virus isolation was in human intestinal tumour-derived differentiated epithelial cell lines; such cell lines may be useful for the isolation and identification of enteroviruses in clinical samples.

Isolation and identification of enteroviruses from faecal samples in a differentiated epithelial cell line (HRT-18) derived from human rectal carcinoma.

A human rectal carcinoma-derived differentiated epithelial cell line, HRT-18, was inoculated with faecal samples in an attempt to grow coronavirus-like particles (CVLP), which are widely prevalent in human stools in southern India. While CVLP did not grow in this cell line, a variety of enteroviruses were isolated from 48 of the 114 stool samples from healthy controls and patients with diarrhoea. The results suggest that human gastrointestinal tumour-derived differentiated epithelial cells in continuous culture may be useful for the primary isolation of enteroviruses and merit further study.

Faecal free fatty acids in tropical sprue and their possible role in the production of diarrhoea by inhibition of ATPases.

Faecal excretion of fatty acids is increased in patients with tropical sprue because of unabsorbed dietary fatty acids. The excretion of fatty acids correlates well with faecal wet weight. In vitro unsaturated fatty acids inhibited Na K-ATPase and Mg-ATPase isolated from basolateral membranes of enterocytes and colonocytes. These findings are a possible explanation for the observed abnormalities in water and electrolyte absorption by the colon in patients with tropical sprue and steatorrhoea.

Evidence regarding the minimal daily requirement of dietary vitamin B12.

The minimal daily requirement of dietary vitamin B12 is defined as that amount which must be ingested in the diet to prevent the occurrence of megaloblastosis, anemia, or other manifestations of vitamin B12 deficiency. An attempt has been made to define this requirement by studying hematological responses to varying amounts of the vitamin in five south Indian subjects with vitamin B12 deficiency anemia (one due to gastric atrophy and four due to dietary deficiency). Amounts ranging from 0.07 to 0.25 micrograms of dietary vitamin B12 were shown to be inadequate but amounts ranging from 0.3 to 0.65 microgram were adequate or possibly more than adequate. It is concluded that the minimal daily requirement of dietary vitamin B12 for the average south Indian adult is in the region of 0.5 microgram/day and that an intake of 1.0 microgram/day would cover the needs of the vast majority of the population and allow a wide margin of safety.