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Structure and function of intestinal mucin: developmental aspects.

Mucin glycoproteins are thought to play an important role in protecting the intestine from chemical or physical injury but the mechanisms of protection and the possible relationship between mucin structure and function are incompletely understood. Structurally, purified intestinal mucins are a heterogeneous and polydisperse group of large-molecular-weight glycoproteins which have regional and developmental differences in composition. Newborn mucin contains more protein and less carbohydrate than adult mucin and differs from adult mucin in buoyant density and mobility on electrophoresis. The primary function of mucin, protection of the intestine, appears to be dependent upon at least four factors: the rate and quantity of mucin release; the physical barrier of the viscous mucus blanket; the provision of specific inhibitory binding sites to infectious agents and proteins, and the inclusion of secretory immunoglobulins to provide a link to the immunologic component of the intestinal host defense system. Immune as well as infectious and chemical agents appear to play an important role in mucus release but developmental effects have not been studied. Preliminary studies indicate that developmental differences may exist in the provision of inhibitory binding sites and the inclusion of secretory immunoglobulins in mucin. These studies indicate that mucus may provide a link between the physical and immunological components of the intestinal host defense system and point to the need for further studies in this area.

Animals↗

Clinical studies in adults presenting with giardiasis to a gastro-intestinal unit.

Eight adults presenting with giardiasis to a gastrointestinal unit during a two year period were studied in detail. Symptoms were varied, diarrhoea occurring in only five patients. Four of the eight gave a history of travel to endemic zones, and three of those who gave no such history had possible predisposing conditions (gastric surgery (2), and borderline IgA deficiency (1]. Most patients exhibited mild malabsorption of fat and vitamin B12, and some abnormality of jejunal disaccharidases was usual. Jejunal histology varied from normal to partial villous atrophy, and the intraepithelial lymphocyte count was raised in those patients with the most marked histological abnormality. Treatment with metronidazole was uniformly successful, and most of the above abnormalities reverted to normal within a month of treatment.

Adult↗

Immunological characteristics of patients infected with common intestinal helminths: results of a study based on reverse-transcriptase PCR.

To determine whether common helminth infections could modify the intestinal immunopathological status of the host, the expression in the human duodenal mucosa of cytokines, eosinophil- and mast-cell-specific molecules and monosaccharide transporters of the glucose-transporter (GLUT) family was explored. The 31 subjects were all patients at the gastro-intestinal disease unit of Nongkhai Hospital, Thailand. Four of the 10 patients who presented with eosinophilia (> or = 6.0% of their leucocytes were eosinophils), and five of the other 21 patients, had intestinal infections with helminths when they presented or within the previous 3 months. Studies based on semi-quantitative, reverse-transcriptase PCR revealed that the interleukin-5/interferon-gamma ratio was significantly higher in the noneosinophilic, helminth-infected patients than in the non-eosinophilic, uninfected patients, whereas the IgE receptor type I (Fc epsilon RI)/mast-cell tryptase ratio was significantly higher in the eosinophilic, helminth-infected patients than in the eosinophilic, uninfected patients. Expression of Charcot-Leyden-crystal protein, GLUT-1 and GLUT-5, however, showed no significant inter-group differences. Principal-components analysis of the data on eosinophils, interleukin-5, interferon-gamma, Fc epsilon RI and mast-cell tryptase revealed that one principal component could discriminate the patients who had helminth infection from the non-eosinophilic, uninfected patients, but not from the eosinophilic, uninfected patients. These results indicate that, whatever the intestinal pathology, patients infected with common intestinal helminths tend to develop a mucosal immunological response of the Th2 type.

Adult↗

Rectal bleeding in Egyptian children.

AIM: In a prospective study to outline the aetiology of bleeding per rectum (BPR) in Egyptian infants and children, a subsidiary aim was to define some of the clinical characteristics of the different aetiologies. SUBJECTS AND METHODS: 194 children with BPR are described. The diagnostic work-up included laboratory investigations, radiological and endoscopic assessment, radio-isotope scanning, angiography and histopathological examination of mucosal biopsies, as appropriate. RESULTS: Ages ranged from 3 to 192 months with a mean (SD) of 49.8 (43.5). Infectious enterocolitis was the most common cause (37.1%). Others included colorectal polyps (21.1%), chronic colitis (16%) including inflammatory bowel diseases (5.2%), allergic colitis (2.6%), solitary rectal ulcer syndrome (1.5%) and non-specific colitis (6.7%). Intussusception and Meckel's diverticulae were the cause in 7.3% and 2.6%, respectively, while other aetiologies included vascular (6.2%), systemic (3.6%), local anal (3.1%) and upper gastro-intestinal causes (1.5%). In 1.5% of cases, the cause remained 'obscure'. CONCLUSION: In Egyptian children, infectious enterocolitis followed by colorectal polyps and chronic colitis are major causes of BPR.

Acute Disease↗

Intestinal disease and the urban environment.

Factors in the urban environments of highly industralized societies are important causes of disease. This review examines urban diseases of small and large intestine. The urban environment is pervaded by chemicals including drugs, food additives, pesticides, industrial products, etc., which are potential causes of disease. Examples of typical urban, as contrasted with rural, intestinal disease are considered in terms of differing etiological factors. Urban intestinal disease is examined from the following standpoints: the population at risk; the chemical agents to which the population is exposed; a model for the physiology of distribution and metabolism of chemicals in relation to the alimentary tract; the application of this model to treatment of an industrial disease; a major urban disease of the alimentary tract, carcinoma of the colon, considered in terms of this model; approaches to characterizing, identifying, and controlling urban intestinal disease.

Bacterial Infections↗

Encysted parasitic larvae in the mouth.

Oral appearances of intestinal parasitic disease are rare. One such appearance is the presence in oral tissues of encysted or encapsulated larvae of organisms from the classes Cestoidea and Nematoda. Cestode larvae form cyst-like lesions that are often clinically diagnosed as mucoceles. In these lesions, the cyst cavity is lined by fibrous tissue with inflammatory cells, and contains fluid and the larval stage of a parasite. The diagnosis of these parasitic cysts is more frequently made in younger persons. The cysts may be treated by simple excision, but care must be taken that the cyst does not rupture, as in some parasites this may result in new cyst formation. Nematode infection in the oral cavity, the most common of which appears to be trichinosis, is rarely reported. Patients with oral or maxillofacial (or both) parasitic disease must undergo a thorough medical investigation to exclude possible life-threatening involvement in other parts of the body.

Adult↗

Nectomys squamipes (Rodentia: Cricetidae) as an experimental model for Schistosomiasis mansoni.

Twenty specimens of Nectomys squamipes born in captivity, were infected with 500 cercariae by the transcutaneous route. Coprologic examinations were carried out from the 5th to 23rd week after infection. On the 7th, 8th, 12th, 16th, and 23rd weeks the animals were sacrificed and perfused. The oogram was performed in segments of the small intestine (proximal, medial and distal portions) and the large intestine. The average pre-patent period was of 42 days. The average number of eggs varied from 350 on the 6th week, to 800 on the 13th. From the 14th week on, the average number of eggs eliminated was lower than 50 per gram of feces. The recovery of worms kept steady on the 7th, 8th and 12th week (16.85%; 15.45% and 11.95%), decreasing to 7.70% on the 16th week and 8.45% on the 23rd week. The proportion of male/female worms was about the same on the first two weeks, but from the 12th week on, the proportion was: 1.4/1 on the 12th week; 2.5/1 on the 16th week and 1.8/1 on the 23rd week. These observations suggest that N. squamipes may be used as an experimental model for schistosomiasis mansoni, to which it develops resistance mechanism, useful for immunity studies.

Animals↗

Intestinal fibrovascular nodules caused by Schistosoma mansoni infection in Calomys callosus Rengger, 1830 (Rodentia: Cricetidae): a model of concomitant fibrosis and angiogenesis.

Human schistosomiasis develops extensive and dense fibrosis in portal space, together with congested new blood vessels. This study demonstrates that Calomys callosus infected with Schistosoma mansoni also develops fibrovascular lesions, which are found in intestinal subserosa. Animals were percutaneously infected with 70 cercariae and necropsied at 42, 45, 55, 80, 90 and 160 days after infection. Intestinal sections were stained for brightfield, polarization microscopy, confocal laser scanning, transmission and scanning electron microscopies. Immunohistological analysis was also performed and some nodules were aseptically collected for cell culture. Numerous intestinal nodules, appearing from 55 up to 160 days after infection, were localized at the interface between external muscular layer and intestinal serosa, consisting of fibrovascular tissue forming a shell about central granuloma(s). Intranodular new vessels were derived from the vasculature of the external vascular layer and were positive for laminin, chondroitin-sulfate, smooth muscle alpha-actin and FVIII-RA. Fibroblastic cells and extracellular matrix components (collagens I, III and VI, fibronectin and tenascin) comprised the stroma. Intermixed with the fibroblasts and vessels there were variable number of eosinophils, macrophages and haemorrhagic foci. In conclusion, the nodules constitute an excellent and accessible model to study fibrogenesis and angiogenesis, dependent on S. mansoni eggs. The fibrogenic activity is fibroblastic and not myofibroblastic-dependent. The angiogenesis is so prominent that causes haemorrhagic ascites.

Animals↗

[Prevalence of anemia in pregnancy, Pucallpa Regional Hospital, Perú].

Population based health surveys in Peru show that the general fertility rates, proportion of pregnant adolescents, and maternal and child morbidity are higher in the jungle regions than in other parts of the country. Endemic intestinal parasitic diseases increase the risk of anemia in pregnant women already suffering from iron, folic acid, and other nutritional deficiencies. This is the most common complication of pregnancy in many Latin American countries and is often associated with premature labor, low birthweight, and perinatal mortality. There are very few studies on this subject based on jungle populations and no reliable estimates of the prevalence of anemia in local pregnant women. The present study was designed to determine the prevalence of anemia in pregnant women attending the Regional Hospital in Pucallpa, located in the Peruvian jungle, from January 1993 to June 1995. This cross-sectional study, which was based on the registries of prenatal and childbirth services encompassing 1,015 pregnant women, looked into the potential association between anemia and such variables as the mother's chronological age, schooling, previous pregnancies, and weight at the beginning of pregnancy. Maternal hemoglobin levels were compared with the newborns' weight at birth. The prevalence of anemia in this population sample was 70.1%. This value was not modified when adjusted for maternal age, schooling, or interval between births. Anemia prevalence was directly related to the number of previous pregnancies and inversely related to weight gain during pregnancy. The perinatal mortality rate was 37.7 per 1,000 births. Neither this rate nor the birthweights were associated with the mother's degree of anemia. A multivariate regression analysis showed that maternal body weight at the start of pregnancy (P = 0.0001), weight gain during pregnancy (P = 0.0001), and the number of pregnancies (P = 0.008) are predictors of birthweight. Results showed that the high prevalence of anemia in Pucallpa's pregnant women is not associated with low birthweight or a high perinatal mortality rate. Future studies should investigate the principal causes of anemia in the pregnant women of Pucallpa and how the disease affects the psychomotor development of their offspring.

Adolescent↗

Cestodiasis with intestinal diverticulosis in a lesser flamingo (Phoeniconaias minor).

An adult female lesser flamingo (Phoeniconaias minor), caught in the African Rift Valley in 1991 and subsequently housed at the Baltimore Zoo, died of severe visceral gout in 1996. Necropsy revealed a white, moderately firm, nodular lesion, 1 cm in diameter, in the serosal wall of the small intestine. Although it was initially thought to be a tumor or focal granuloma, histologic examination revealed multiple cestodes deeply embedded at the base of the crypts between the intestinal villi, with their massive scolices (up to 3.4 mm in diameter) distending these spaces into multiple diverticulae. The mucosal epithelium surrounding the scolices was severely attenuated. Around the diverticulae, in the submucosa and muscularis, was a mild to moderate lymphocytic reaction and mild fibrosis. The proximity of multiple scolices and extensive invasion of host tissue suggested that the infection occupied a preexisting lesion. The cestodes were cyclophyllids but were distinct from any species previously reported from flamingos. Helminths should be included in differential diagnoses for gastrointestinal nodules in flamingos.

Animals↗

Cryptosporidium sp.-associated enteritis without gastritis in rough green snakes (Opheodrys aestivus) and a common garter snake (Thamnophis sirtalis).

An epizootic of severe Cryptosporidium sp.-associated enteritis occurred in a group of 15 wild-caught juvenile rough green snakes (Opheodrys aestivus) at the Baltimore Zoo quarantine facility. All of the animals died with no premonitory signs. Histopathologic examination of the small and proximal large intestine of eight of the green snakes showed moderate to severe Cryptosporidium sp. infection and enteritis characterized by dense heterophilic and lymphocytic inflammatory infiltrates throughout the lamina propria with epithelial necrosis. Cryptosporidium sp. was also found in feces of an adult common garter snake (Thamnophis sirtalis) that was wild caught on zoo grounds and held in quarantine during the epizootic. After euthanasia, histologic examination of the garter snake showed a severe small intestinal Cryptosporidium sp. infection with only mild enteritis consisting of sparse heterophilic and lymphocytic infiltrates. There was no gross or histologic evidence of Cryptosporidium sp. gastritis in the nine snakes evaluated, and this is the first report of Cryptosporidium sp.-associated enteritis in snakes without gastric lesions.

Animals↗

Endogenous development of Eimeria minasensis in experimentally infected goats.

The endogenous development of Eimeria minasensis was studied in 9 coccidia-free goat kids inoculated with 10(5) sporulated oocysts/kg body weight. Kids were killed 4, 7 (2 animals), 10, 13, 16, 18, 19, and 22 days after inoculation (DAI). In tissue sections of the intestines stained with hematoxylin and eosin and examined by light microscopy, 2 generations of meronts, gamonts, gametes, and oocysts were found. The first generation of meronts developed in cells deep in the lamina propria of the jejunum and ileum. Mature giant meronts (299.4x243.8 microm) found 16 DAI were visible to the naked eye and contained a large number of crescent-shaped merozoites. The second generation of meronts developed in the epithelial cells of crypts of the ileum and above the host cell nuclei. Mature meronts (11.5x10.1 microm) with 18-28 comma-shaped merozoites were first seen 16 DAI. Gametogenesis took place in epithelial cells of the crypts and villi of the terminal part of the ileum, cecum, and colon. Macrogametes (27.8x17.6 microm), mature microgamonts (21.3x17.0 microm), microgametes, and oocysts (30.5x19.4 microm) were found 19 DAI. Sexual stages were below the host cell nucleus.

Animals↗

Potential interactions between the intestinal helminths of the cichlid fish Cichlasoma synspilum from southeastern Mexico.

This study presents and analyzes positional data on 18 helminth species forming the intestinal infracommunities of 59 Cichlasoma synspilum from southeastern Mexico. Interspecific interactions were found between 4 pairs of host specialists: Crassicutis cichlasomae (Digenea) with Neoechinorhynchus golvani (Acanthocephala), Spirocamallanus rebecae (Nematoda) with N. golvani, and Raillietnema kritscheri (Nematoda) with N. golvani. The interactions were expressed as negative correlations, positional shifts, and reductions in realized distribution. It is suggested that N. golvani produces unsuitable habitats for C. cichlasomae, S. rebecae, and R. kristscheri. All interactions were found among phylogenetically unrelated helminth specialists of cichlids.

Animals↗

Clinical coccidiosis in raccoons (Procyon lotor).

Clinical coccidiosis was diagnosed in wild-caught and captive raccoons. Eimeria procyonis-like oocysts were seen in 15 of 15 captive raccoons. In 6 of 6 juvenile wild-caught raccoons examined at necropsy, endogenous coccidian stages were seen in the small intestine. Two types of schizonts (large and small) were identified. Large schizonts were up to 110 microm long, contained 10-microm-long merozoites, and were in crypt glandular epithelial cells. Smaller schizonts were 10 microm long, contained 5-microm-long merozoites, and were at the tips of the villi. Only a few gamonts and no oocysts were seen in sections. These stages were thought to be of E. procyonis.

Animals↗