Butyrate and glucose metabolism by colonocytes in experimental colitis in mice

BACKGROUND/AIMS

Impaired colonocyte metabolism of butyrate has been implicated in the aetiopathogenesis of ulcerative colitis. Colonocyte butyrate metabolism was investigated in experimental colitis in mice.

METHODS

Colitis was induced in Swiss outbred white mice by oral administration of 4% dextran sulphate sodium (DSS). Colonocytes isolated from colitic and normal control mice were incubated with [(14)C]butyrate or glucose, and production of (14)CO(2), as well as of intermediate metabolites (acetoacetate, beta-hydroxybutyrate and lactate), was measured. The effect of different substrate concentrations on oxidation was also examined.

RESULTS

Butyrate oxidation (micromol/h per mg protein; mean (SEM)) was significantly reduced in DSS colitis, values on day 7 of DSS administration being 0.177 (0.007) compared with 0.406 (0.035) for control animals (p<0.001). Glucose oxidation (micromol/h per mg protein; mean (SEM)) on day 7 of DSS administration was significantly higher than in controls (0.06 (0.006) v 0.027 (0.004), p<0.001). Production of beta-hydroxybutyrate was decreased and production of lactate increased in DSS colitis compared with controls. Increasing butyrate concentration from 10 to 80 mM enhanced oxidation in DSS colitis (0.036 (0.002) to 0.285 (0.040), p<0.001), although it continued to remain lower than in controls. Surface and crypt epithelial cells showed similar ratios of butyrate to glucose oxidation. When 1 mM DSS was added to normal colonocytes in vitro, it did not alter butyrate oxidation. The initial histological lesion of DSS administration was very patchy and involved crypt cells. Abnormal butyrate oxidation became apparent only after six days of DSS administration, at which time histological abnormalities were more widespread.

CONCLUSIONS

Colonocyte metabolism of butyrate, but not of glucose, is impaired in DSS colitis, and may be important in pathophysiology. Histological abnormalities preceded measurable defects in butyrate oxidation.

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.

Segmental colonoscopic biopsies in the differentiation of ileocolic tuberculosis from Crohn's disease

BACKGROUND AND AIM

The differentiation between Crohn's disease (CD) and tuberculosis (TB) of the intestine can be difficult in areas where both diseases occur. The present study examined histological criteria that would enable the diagnosis in mucosal biopsies.

METHODS

Colonoscopic biopsies from 33 patients with TB and 31 patients with CD were examined for several specific histological features and their distribution.

RESULTS

The salient distinguishing features of TB were granulomas larger than 400 microm in maximum dimension, more than four sites of granulomatous inflammation per site, cessation, a band of epithelioid histiocytes in ulcer bases and location of granulomas in the caecum. The salient features of CD were granulomas not showing any of the above features, focally enhanced colitis, pericryptal granulomatous inflammation, and the presence of architectural alteration/activity/chronic inflammation/deep ulceration at sites that did not show granulomatous response in the same or adjacent segments. Although granulomas in CD were distributed throughout the colon, they were more frequent in the rectosigmoid than in TB. All biopsies from endoscopically abnormal sites did not show distinguishing features of TB or CD, emphasizing the need for multiple biopsies. There was an accrual in the number of diagnoses made with increasing numbers of biopsies from rectum to ileum.

CONCLUSIONS

Histology of mucosal biopsies can aid in the differentiation of TB from CD, but multiple biopsies from different colonic segments are important for complete evaluation.

Oxidative stress in the development of liver cirrhosis: a comparison of two different experimental models

BACKGROUND/AIMS

Oxidative stress has been implicated in liver cirrhosis. Carbon tetrachloride and thioacetamide are the most widely used models to develop cirrhosis in rats and the present study compares oxidative stress in the liver induced by these compounds at different stages of cirrhosis development.

METHODS

Twice-weekly intragastric or intraperitoneal administration of carbon tetrachloride or thioacetamide, respectively, produced liver cirrhosis after 3 months. Histology, serum markers and hepatic hydroxy proline content confirmed the cirrhosis.

RESULTS

An increase in oxidative stress parameters was seen in mitochondria, peroxisomes and microsomes from the liver after carbon tetrachloride or thioacetamide treatment. Oxidative stress was more severe in carbon tetrachloride treated animals than thioacetamide. Mild oxidative stress was evident at 1 and 2 months of treatment and a significant increase was seen by 3 months of treatment with either compound. By this time, frank liver cirrhosis was also observed.

CONCLUSIONS

These results suggest that evidence of oxygen free radicals is also found early in the development of fibrosis and cirrhosis in both models.

Increased permeability in dextran sulphate colitis in rats: time course of development and effect of butyrate

BACKGROUND

Increased mucosal permeability is an important factor in the genesis of mucosal inflammation in inflammatory bowel disease. This study examined the time course of increased permeability and the effect of butyrate on permeability in experimental colitis in rats.

METHODS

Colitis was induced in albino rats by administration of 4% dextran sulphate sodium (DSS) orally for up to 7 days. Rats were killed sequentially after 1-7 days of DSS feeding and compared with control animals. Distal colon sheets, from normal and DSS rats, were mounted in Ussing chambers. Electric resistance and passive permeation of 14C-mannitol were measured over 90 min. In control and 5-day DSS rats additional permeability measurements were made in the presence of butyrate (25 mmol/l) in the bathing solutions. The permeability of the normal distal colon was measured after addition of DSS in vitro. Sections of colon were examined by light microscopy. The viability of colonocytes, from normal and DSS rat colon, was measured by release of lactate dehydrogenase immediately and during a 60-min incubation after isolation.

RESULTS

Focal mild inflammation and shedding of epithelium were noted after 2 days of DSS administration; crypt loss with flattened epithelium in adjacent areas after 5 days; and fibrosis after 7 days. Decreased epithelial cell survival after 60 min of incubation was noted after 1 day of DSS administration, whereas decreased viability at the time of isolation was noted after 2 days of DSS administration (viability, 72.7% +/- 1.4%; mean +/- standard error) compared with control (89.3% +/- 0.8%) (P < 0.01). Increased permeability was noted after 1 day of DSS administration. Electric resistance (mu omega/cm2/h) was significantly reduced after 1 day of DSS administration to 85.9 +/- 4.6 (mean +/- standard error) compared with control animals (117.2 +/- 2.2; P < 0.001). Serosa-mucosa flux of mannitol (micromol/cm2/h) was also significantly increased after 1 day of DSS feeding (0.169 +/- 0.01) compared with control (0.061 +/- 0.08) (P < 0.01). Electric resistance and mannitol permeability were significantly returned towards normal by the presence of butyrate. DSS added directly to the bathing solution did not significantly alter the colon permeability in vitro.

CONCLUSIONS

Increased mucosal permeability is a very early change in colitis induced by DSS, is accompanied by decreased cell survival, and precedes detectable changes in histology. Reversal of increased mucosal permeability by butyrate may explain its utility in the therapy of inflammatory disease of the colon.

How reliable an indicator of inflammation is myeloperoxidase activity?

BACKGROUND

Myeloperoxidase (MPO) and interleukin-6 (IL-6) are often used as markers of inflammation. The aim of this study was to ascertain whether MPO activity is as reliable as IL-6 as an indicator of inflammation.

METHODS

Inflammation was induced in mice, using either turpentine or indomethacin. Duodenal tissue was removed from these animals at various time periods ranging from 6 h to 7 days later. Concentrations of IL-6 and MPO activity were estimated in the tissue. Histopathological examination was also carried out at some of the time periods to determine the presence of neutrophil infiltration in turpentine-treated mice.

RESULTS

Concentrations of IL-6 and MPO activity were significantly higher in tissue that had been treated with the agents used, at all the time periods studied, when compared with corresponding control tissue. Fold-increases in MPO activity were higher than fold-increases in IL-6. Concentrations of the 2 parameters showed significant positive correlation. Histopathological examination did not show significantly higher numbers of neutrophils infiltrating the tissue in response to turpentine, at the time periods studied.

CONCLUSIONS

Estimation of MPO activity is a reliable indicator of inflammation, being more sensitive than histopathological examination of tissue and as good as measurement of IL-6 concentrations.

Indomethacin-induced free radical-mediated changes in the intestinal brush border membranes

Nonsteroidal anti-inflammatory drugs (NSAIDs) cause small intestinal damage but the pathogenesis of this toxicity is not well established. Our earlier work has shown that villus enterocytes are most susceptible to the effects of indomethacin, a commonly used NSAID. This study looked at the acute effect of indomethacin on brush border membranes (BBM), which are present mainly in the villus cells and are in immediate contact with the contents of the small intestinal lumen. Evidence of oxidative stress was found in the mucosa of the small intestine of rats dosed with indomethacin, as indicated by increased activity of xanthine oxidase with corresponding decrease in the levels of several free radical scavenging enzymes. These changes were associated with an increase in peroxidation parameters in the BBM and a fall in the level of alpha-tocopherol. These BBM also exhibited impairment in glucose transport. Significant changes were seen in the lipid composition of these membranes, with upregulation of an 85kDa isoform of phospholipase A(2). Pretreatment of animals with allopurinol, arginine or zinc protected against these effects of indomethacin. Thus this study suggests that in an acute model of indomethacin dosing there is impairment in structure and function of the BBM in enterocytes, with the effects possibly mediated by free radicals and phospholipases.

In situ PCR for Mycobacterium tuberculosis in endoscopic mucosal biopsy specimens of intestinal tuberculosis and Crohn disease

Tuberculosis and Crohn disease are granulomatous disorders affecting the intestinal tract with similar clinical manifestations and pathologic features. We evaluated the use of in situ polymerase chain reaction (PCR) using Mycobacterium tuberculosis complex-specific primers for IS 6110 to differentiate these 2 disorders in archival mucosal biopsy specimens. In situ PCR was positive in 6 of 20 tuberculosis biopsy specimens and 1 of 20 Crohn disease biopsy specimens. Staining was localized to a site of granulomatous inflammation in 3 of the tuberculosis specimens and in the Crohn disease specimen. In the other tuberculosis biopsy specimens, positive staining was localized to inflammatory granulation tissue and to a focus of intact mucosa without granulomatous inflammation. The presence of M tuberculosis DNA in Crohn disease could be due to coexisting latent tuberculosis or indicate a role for these bacteria in triggering an abnormal immune response. Therefore, in situ PCR is potentially useful to differentiate intestinal tuberculosis from Crohn disease, if the sensitivity is improved.

Collagenous gastritis and collagenous colitis: a report with sequential histological and ultrastructural findings

The case is reported of a young adult man with collagenous gastritis, an extremely rare disorder with only three case reports in the English literature, who subsequently presented with collagenous colitis. Sequential gastric biopsies showed a notable increase in thickness of the subepithelial collagen band. Ultrastructural study of gastric and rectal mucosa showed the characteristic subepithelial band composed of haphazardly arranged collagen fibres, prominent degranulating eosinophils, and activated pericryptal fibroblasts.

Intestinal mucosal alterations in rats with carbon tetrachloride-induced cirrhosis: changes in glycosylation and luminal bacteria

Spontaneous bacterial peritonitis is a major cause of mortality after liver cirrhosis. Altered permeability of the mucosa and deficiencies in host immune defenses through bacterial translocation from the intestine due to intestinal bacterial overgrowth have been implicated in the development of this complication. Molecular mechanisms underlying the process are not well known. In order to understand mechanisms involved in translocation of bacteria, this study explored the role of oxidative stress in mediating changes in intestinal mucosal glycosylation and luminal bacterial content during cirrhosis. CCl4-induced cirrhosis in rats led to prolonged oxidative stress in the intestine, accompanied by increased sugar content of both intestinal brush border and surfactant layers. This was accompanied by changes in bacterial flora in the gut, which showed increased hydrophobicity and adherence to the mucosa. Inhibition of xanthine oxidase using sodium tungstate or antioxidant supplementation using vitamin E reversed the oxidative stress, changes in brush border membrane sugar content, and bacterial adherence. In conclusion, oxidative stress in the intestine during cirrhosis alters mucosal glycosylation, accompanied by an increased hydrophobicity of luminal bacteria, enabling increased bacterial adherence onto epithelial cells. This might facilitate translocation across the mucosa, resulting in complications such as spontaneous bacterial peritonitis.

Etiology of diarrhea in patients undergoing allogeneic bone marrow transplantation in South India

BACKGROUND

No studies so far have examined enteric infections in patients undergoing bone marrow transplantation (BMT) in developing countries where asymptomatic carriage and colonization with enteric pathogens is frequent.

METHODS

A prospective study followed 65 patients who underwent BMT in South India between 1995 and 1998. Patients were screened for enteric pathogens before transplantation, weekly during the first 4 weeks after transplantation, and during all episodes of diarrhea.

RESULTS

Enteric pathogens were found in 60% of patients before or after transplantation. Pretransplantation screening revealed asymptomatic excretion of enteric pathogens in 29% (19/65). Forty-eight percent of patients undergoing BMT developed diarrhea. Diarrhea was mainly of noninfectious origin in the first 20 days after transplantation. More than 20 days after transplantation, the major causes of diarrhea were graft-versus-host disease and infection. Parasitic infections other than Cryptosporidium did not contribute significantly to morbidity in the pre- and posttransplantation period. Rotavirus and adenoviruses were found in approximately 12% and 5% of subjects, respectively. Bacterial infections in the posttransplantation period were found to be more common in India than in developed countries. Clostridium difficile-associated diarrhea was seen in the posttransplantation period but not before transplantation. Enterotoxigenic and enterohemorrhagic Escherichia coli caused symptomatic infections in the posttransplantation period, but the association of other classes of diarrheogenic E. coli with diarrhea was doubtful.

CONCLUSIONS

There was significantly higher mortality (P<0.01) in patients with symptomatic or asymptomatic gastrointestinal infections caused by bacteria than in patients with parasitic or viral infections or without enteric infections.

Indomethacin-induced renal damage: role of oxygen free radicals

Nonsteroidal anti-inflammatory drugs are used extensively in clinical medicine. In spite of their therapeutic utility, however, they are known to cause significant gastrointestinal and renal toxicities, circumstances that limit their use. The side effects produced in these organs have been attributed mainly to the inhibitory effect of these drugs on the activity of cyclooxygenase, a key enzyme in prostaglandin synthesis. In addition to this, in the small intestine it is known that reactive oxygen species also contribute to the enteropathy seen in response to these drugs. In the kidney, however, there is little information whether other mechanisms contribute to the renal toxicity. This study was designed to look at the possible biochemical mechanisms involved in indomethacin-induced renal damage. Rats fasted overnight were dosed with indomethacin (20 mg/kg) by gavage and sacrificed 24 hr later. Histology of the kidney showed abnormalities in the mitochondria in the proximal tubules. Evidence of oxidative stress was found in the kidney associated with mitochondrial dysfunction and neutrophil infiltration. The lipid composition in the mitochondria was also altered. Such effects were abolished by the prior administration of arginine, a donor of nitric oxide. This study, thus, suggests that one of the mechanisms by which nonsteroidal anti-inflammatory drugs induce renal damage is through oxygen free radicals possibly generated by activated neutrophils and mitochondrial dysfunction.

Quantitative and ultrastructural analysis of rectal mucosal mast cells in acute infectious diarrhea

The role of mast cells, potential mediators of mucosal immunity and inflammation, was studied morphologically in the rectal mucosa in two acute diarrheal diseases, cholera and shigellosis. Quantitation of mucosal mast cells showed that they were significantly higher in the deeper lamina propria where blood vessels and nerves were more abundant. There was no difference in mast cell counts or degranulation in the mucosa in both groups of patients and controls. Intraepithelial mast cells were decreased in the patients. The prevalence of lipid bodies was significantly higher in mast cells from patients with cholera and shigellosis (P < 0.01). These findings suggest that mast cell populations are more dense around blood vessels and nerves and that inflammatory mediators derived from arachidonic acid metabolites, as indicated by the lipid bodies, are the response of mast cells to the alterations in diarrhea, despite differences in the etiology of diarrhea.

A monkey model for enterohemorrhagic Escherichia coli infection

Adult Macaca radiata (n=22) were infected intragastrically with 10(12) Escherichia coli O157:H7 strain 84-01, which produces Shiga toxins 1 and 2. Clinical symptoms and bacterial excretion were documented in each monkey for a specified time period before they were killed. At necropsy, samples were obtained for culture and histologic and ultrastructural examination. Seventeen monkeys had diarrhea: E. coli O157 was isolated from postinfection stool samples from all monkeys and from autopsy cultures for 14 of 22 monkeys. Histologic examination showed attaching-effacing lesions, which appeared at 12 h and persisted for 7 days, in 12 monkeys. Widening of the intercellular spaces, degeneration and vacuolization of the epithelial cells, epithelial tufting, extrusion of epithelial cells, and neutrophilic infiltration were characteristic features seen in 20 of the 22 infected monkeys but not in 4 control monkeys. This monkey model closely parallels the early stages of the disease produced by E. coli O157:H7 and would be useful in the further study of pathogenic mechanisms and prevention methods in enterohemorrhagic E. coli infections.

Retinoid metabolism during development of liver cirrhosis

The changes in retinoid metabolism have been documented in liver cirrhosis. However, the dynamic alterations in levels of this vitamin between circulation and liver during development of the liver cirrhosis are not well understood. The aim of this study was to measure retinoids in the liver and circulation in parallel, during and after development of cirrhosis induced by carbon tetrachloride and thioacetamide. Retinoid levels were measured by HPLC. A decrease in retinaldehyde and total retinol, together with an increase in retinoic acid was evident in liver from both carbon tetrachloride or thioacetamide treated rats within a month after initiation of treatment. Activity of enzymes involved in retinoid metabolism such as retinaldehyde oxidase, retinaldehyde dehydrogenase, and retinaldehyde reductase were decreased in the liver. In parallel, levels of retinol and retinaldehyde in the serum were increased while retinoic acid was decreased. This study indicates that during development of cirrhosis, there is reciprocal transfer of retinoid metabolites between the circulation and the liver.

Renal damage in experimentally-induced cirrhosis in rats: Role of oxygen free radicals

Cirrhosis with ascites is associated with impaired renal function accompanied by sodium and water retention. Although it has been suggested that mediators such as nitric oxide play a role in the development of renal failure in this situation, other mechanisms underlying the process are not well understood. This study examined the role of oxidative stress in mediating renal damage during the development of cirrhosis in order to understand mechanisms involved in the process. It was shown that carbon tetrachloride- or thioacetamide-induced cirrhosis in rats results in oxidative stress in the kidney as seen by increased lipid peroxidation and protein oxidation, accompanied by altered antioxidant status. Cirrhosis was also found to affect renal mitochondrial function, as assessed by measurement of the respiratory control ratio, the swelling of mitochondria, and calcium flux across mitochondrial membranes. Increased lipid peroxidation and changes in lipid composition were evident in the renal brush border membranes, with compromised transport of 14C glucose across these membranes. In conclusion, renal alterations produced as a result of cirrhosis in the rat are possibly mediated by oxidative stress.

Butyrate hastens restoration of barrier function after thermal and detergent injury to rat distal colon in vitro

BACKGROUND

Epithelial migration restores barrier function after superficial injury to any mucosa. The present study aimed to determine whether butyrate, important to colonic epithelial physiology in diverse ways, influences restoration of barrier function in the injured rat colon.

METHODS

Rat distal colon was transiently exposed in vitro to heat (55 degrees C for 10 sec) or to detergent (deoxycholic acid, 7.5 mM, for 15 min), and tissue damage was verified histologically. Epithelial barrier function was assessed, in colon tissue mounted in Ussing chambers, by measuring electric resistance and passive serosa-to-mucosa fluxes of 22Na and of 14C PEG 4000 under voltage clamp conditions. Studies were done in the absence and presence of 25 mM butyrate in the bathing solutions.

RESULTS

Heat exposure induced superficial epithelial damage, and the electric resistance decreased significantly. This was accompanied by increase in flux of 14C PEG and increased passive flux of 22Na. Electric resistance was significantly higher, and PEG flux significantly lower, in tissues bathed with butyrate. Exposure to deoxycholic acid also induced superficial epithelial damage, reduced tissue electric resistance, and increased passive flux of Na and PEG. Electric resistance was significantly higher, and PEG flux significantly lower, in injured tissues bathed in butyrate, than in injured tissues bathed in butyrate-free solution. The effect of butyrate on restoration of electric resistance towards normal was seen in colon both from adult rats and from younger rats that were 2 or 6 weeks old.

CONCLUSIONS

Butyrate enhanced restoration of mucosal barrier function in rat distal colon in response to heat and detergent injury.

Self-directed learning readiness of Indian medical students: a mixed method study

BACKGROUND

Self-directed learning (SDL) is defined as learning on one's own initiative, with the learner having primary responsibility for planning, implementing, and evaluating the effort. Medical education institutions promote SDL, since physicians need to be self-directed learners to maintain lifelong learning in the ever-changing world of medicine and to obtain essential knowledge for professional growth. The purpose of the study was to measure the self-directed learning readiness of medical students across the training years, to determine the perceptions of students and faculty on factors that promote and deter SDL and to identify the role of culture and curriculum on SDL at the Christian Medical College, Vellore, India.

METHODS

Guglielmino's SDL Readiness Scale (SDLRS) was administered in 2015 to six student cohorts (452 students) at admission, end of 1st, 2nd, 3rd and 4th year of training, and at the beginning of internship in the undergraduate medicine (MBBS) program. Analysis of variance (ANOVA) was used to compare SDL scores between years of training. 5 student focus groups and 7 interviews with instructors captured perceptions of self-direction. Transcripts were coded and analyzed thematically.

RESULTS

The overall mean SDLRS score was 212.91. There was no significant effect of gender and age on SDLR scores. There was a significant drop in SDLRS scores on comparing students at admission with students at subsequent years of training. Qualitative analysis showed the prominent role of culture and curriculum on SDL readiness.

CONCLUSIONS

Given the importance of SDL in medicine, the current curriculum may require an increase in learning activities that promote SDL. Strategies to change the learning environment that facilitates SDL have to be considered.

Investigation into celiac disease in Indian patients with portal hypertension

BACKGROUND

There is limited data on celiac disease in patients with cryptogenic cirrhosis or idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH). Our objective was to evaluate for celiac disease in patients with portal hypertension in India.

METHODS

Consecutive patients with portal hypertension having cryptogenic chronic liver disease (cases) and hepatitis B- or C-related cirrhosis (controls) were prospectively enrolled. We studied tissue transglutaminase (tTG) antibody and duodenal histology in study patients.

RESULT

Sixty-one cases (including 14 NCIPH patients) and 59 controls were enrolled. Celiac disease was noted in six cases (including two NCIPH patients) as compared to none in controls. In a significant proportion of the remaining study subjects, duodenal biopsy showed villous atrophy, crypt hyperplasia, and lamina propria inflammation, not accompanied by raised intraepithelial lymphocytes (IELs); this was seen more commonly in cases as compared to controls. An unexpectedly high rate of tTG antibody positivity was seen in study subjects (66 %) of cases as compared to 29 % in controls (p-value < 0.001), which could indicate false-positive test result.

CONCLUSION

In this study, 10 % of patients with unexplained portal hypertension (cryptogenic chronic liver disease) had associated celiac disease. In addition, an unexplained enteropathy was seen in a significant proportion of study patients, more so in patients with cryptogenic chronic liver disease. This finding warrants further investigation.

Correlation between coinfection with parasites, cytomegalovirus, and Clostridium difficile and disease severity in patients with ulcerative colitis

A cross-sectional study was undertaken to determine whether there was any association between intestinal infection (with parasites, cytomegalovirus, or Clostridium difficile) and clinical disease severity in patients with ulcerative colitis (UC). Consecutive cases of UC were enrolled after history and clinical examination, evaluated for presence of stool parasites (routine/special stains) and C. difficile toxins A and B (CDT) in stools. Segmental biopsies at colonoscopy were assessed for cytopathic changes of cytomegalovirus (CMV) infection. Statistical analysis was done to look for associations between the presence of infection and disease severity as assessed by the Truelove-Witts criteria. Eighty-seven patients (males = 51) of mean (SD) age 40.2 (12) years were enrolled. Thirty-nine patients (44.8 %) had severe disease, 11 (12.6 %) had moderate, and 37 (42.6 %) had mild disease. Ten (11.5 %) patients had parasites detected in stool, two (2.3%) had histological evidence of CMV, and three (3.4 %) were positive for CDT. The presence of pathogens was very significantly associated with moderate/severe UC. Thirteen of 15 cases (86 %) with detectable pathogens had moderate or severe UC compared to 37 of 72 cases (51 %) without detectable pathogens (p = 0.0194). The relative risk of a UC patient with stool pathogens having severe disease was 1.686 (95 % CI 1.250 to 2.276) compared to one without stool pathogens. The presence of stool pathogens was associated with disease severity in UC.

Zinc and zinc related enzymes in precancerous and cancerous tissue in the colon of dimethyl hydrazine treated rats

Trace element zinc deficiency or excess is implicated in the development or progression of some cancers. The exact role of zinc in the etiology of colon cancer is unclear. To cast light on this question, an experimental model of colon carcinogenesis was applied here. Six week old rats were given sub cutaneous injections of DMH (30 mg/kg body weight) twice a week for three months and sacrificed after 4 months (precancer model) and 6 months (cancer model). Plasma zinc levels showed a significant decrease (p<0.05) at 4 months and a greater significant decrease at 6 months (p<0.01) as compared with controls. In the large intestine there was a significant decrease in tissue zinc levels (p<0.005) and in CuZnSOD, and alkaline phosphatase activity (p<0.05) in the pre-cancerous model and a greater significant decrease in tissue zinc (p<0.0001), and in CuZnSOD and alkaline phosphatase activity (p<0.001), in the carcinoma model. The tissue zinc levels showed a significant decrease in the small intestine and stomach (p<0.005) and in liver (p<0.05) in the cancer model. 87% of the rats in the precancer group and 92% rats in the cancer group showed histological evidence of precancerous lesions and carcinomas respectively in the colon mucosa. This study suggests that the decrease in plasma zinc, tissue zinc and activity of zinc related enzymes are associated with the development of preneoplastic lesions and these biochemical parameters further decrease with progression to carcinoma in the colon.

Early activation of mucosal dendritic cells and macrophages in acute Campylobacter colitis and cholera: An in vivo study

BACKGROUND AND AIM

Macrophages and dendritic cells are closely related mononuclear phagocytic cells. Little is known about their in vivo role in acute intestinal bacterial infections in humans. We undertook to evaluate these cells in rectal mucosal biopsies of patients with acute colitis.

METHODS

All mucosal mononuclear phagocytic cells in rectal biopsies of patients with acute Campylobacter colitis (n = 5), shigellosis (n = 5), and cholera (n = 10) were evaluated ultrastructurally and compared with those in controls (n = 5).

RESULTS

Mononuclear phagocytic cells in the superficial rectal mucosa showed a higher prevalence of ultrastructural features of activation in Campylobacter colitis and cholera than in controls. A lower prevalence of features of activation with increased monocytes was seen in shigellosis. Cells with the ultrastructural morphology of activated dendritic cells constituted 41% and 45% of all mononuclear phagocytic cells in two of five patients with Campylobacter colitis and 4-22% of cells in four of 10 patients with cholera. Their presence in patients with Campylobacter colitis was associated with significant surface epithelial damage and prominent acute inflammatory changes in the mucosa.

CONCLUSIONS

This is the first ultrastructural study to show activated macrophages and dendritic cells in vivo in acute Campylobacter colitis and cholera. Dendritic cell activation occurred early in the clinical course of these infections. Surface epithelial damage may play a role in the activation of dendritic cells.

Cytokine gene expression in intestinal tuberculosis and Crohn's disease

BACKGROUND

Intestinal tuberculosis (TB) and Crohn's disease closely resemble each other clinically and morphologically. Little is known of cytokine regulation in intestinal TB.

OBJECTIVE

To compare cytokine gene expression in colonic mucosa and peripheral blood mononuclear cells (PBMC) in TB with that in Crohn's disease.

METHODS

Biopsies were obtained from normal and ulcerated colonic mucosa of 12 intestinal TB and 11 Crohn's disease patients, and PBMC from 15 intestinal TB and 12 Crohn's disease patients and 11 healthy volunteers. RNA was extracted, and the expression of selected cytokines, chemokines and pattern recognition receptors quantified by reverse transcriptase real-time polymerase chain reaction using SYBR green.

RESULTS

The mRNA expression of interleukin-8 (IL-8), induced protein-10, tumour necrosis factor-alpha, IL-23 p19 and IL-12 p40, and Toll-like receptors (TLR) 1 and 2 in the ulcerated mucosa was increased in both intestinal TB and Crohn's disease. Expression of growth-related oncogene-alpha was increased in intestinal TB, while expression of interferon-gamma (IFN-) and TLR 4, 5 and 9 was increased in Crohn's disease. Expression of RANTES (regulated upon activation, normal T-cell expressed and secreted) was decreased in Crohn's disease. Secretion of IFN- or IL-10 from PBMC was not significantly altered in either disease. PBMC mRNA expression of IL-1, IL-6 and IL-8 mRNA was upregulated in Crohn's disease, while that of IL-17 was upregulated in intestinal TB.

CONCLUSIONS

Cytokine gene expression patterns in intestinal mucosa and PBMC of intestinal TB were remarkably similar to Crohn's disease, and demonstrated innate immune activation and T-helper 1 polarisation.