Modulation of mucosal immunity in a murine model of food-induced intestinal inflammation.

BACKGROUND: Hypersensitivity or uncontrolled responses against dietary antigens can lead to inflammatory disorders like food allergy and current models reflect a variety of causes but do not reveal the detailed modulation of gut immunity in response to food antigens after breakdown in mucosal tolerance. OBJECTIVE: To develop and characterize a murine model for food-induced intestinal inflammation and to demonstrate the modulation of gut immune response by dietary allergenic antigens. METHODS: C57BL/6 mice were sensitized with peanut proteins, challenged with peanut seeds and their sera and gut segments were collected for subsequent analyses. RESULTS: Sensitization and challenged with peanut seeds led to alterations in gut architecture with inflammatory response characterized by oedema in lamina propria and cell infiltrate composed mainly by eosinophils, mast cells, phagocytes, natural killer and plasma cells, together with low percentage of gammadelta+ and CD4+CD25+Foxp3+ cells in Peyer's patches. These animals also presented high levels of specific IgE and IgG1 in sera and modulation of mucosal immunity was mediated by increased expression of GATA-3, IL-4, IL-13 and TNF-alpha in contrast to low IFN-gamma in the gut. CONCLUSION: A murine model for food-induced intestinal inflammation was characterized in which modulation of gut immunity occurs by peanut antigens in consequence of T-helper type 2 (Th2) allergic response and failure of regulatory mechanisms necessary for mucosa homeostasis, resembling food allergy. This work shed some light on the understanding of the pathogenesis of gastrointestinal disorders and intolerance in the gut and supports the development of therapies for food-related enteropathies like food allergy, focusing on gut-specific immune response.

Scanning electron microscopic study of the cleaning ability of chlorhexidine as a root-canal irrigant.

AIM: To evaluate in vitro the cleaning of root-canal walls after irrigation with different irrigants. METHODOLOGY: A total of 36 recently extracted human teeth were divided into four experimental groups according to the irrigating solution used: saline; 2% chlorhexidine; 2.5% sodium hypochlorite; and 2.5% sodium hypochlorite + EDTA. The cleaning of the apical, middle and coronal thirds of the root canals was evaluated by scanning electron microscope examination using a 4-point scoring system. RESULTS: The best cleaning was obtained using 2.5% sodium hypochlorite and EDTA, followed by 2.5% sodium hypochlorite only (P < 0.05), whose cleaning was similar to chlorhexidine only in the cervical third. Cleaning by saline and 2% chlorhexidine was worse than the other two groups and was similar in all thirds. Better cleaning was found in the cervical and middle thirds for all groups with the worst results in the apical third. CONCLUSIONS: The apical third of the root canals was not cleaned as well as the middle and coronal thirds. Cleaning by chlorhexidine and saline was inferior compared to the cleaning by sodium hypochlorite with and without EDTA.

The increase of phospholipase C activity induced by orotic acid is unrelated to lipid peroxidation.

Liver phospholipase-C (PL-C) activity proved to be promptly modified in rats fed with an orotic acid (OA) supplemented diet; an increased of PL-C basal activity was demonstrated after 2 days of diet. In the present work the possible involvement of lipid peroxidation was investigated, since 4-hydroxynonenal (HNE) and 4-hydroxyoctenal (HOE), two end-products of lipid peroxidation, have been shown to induce a strong stimulation of hepatic PL-C. Membrane-bound PL-C activity was evaluated together with the rate of TBArs production by liver homogenates obtained from rats fed with a diet containing 1% OA for 2 and 5 days. PL-C activity was measured by following the rate of formation of Ins-P3 from labelled PtdIns-P2 added to isolated liver membranes. TBArs production was unchanged in the livers of rats fed the OA diet, while basal and GTPgammaS-stimulated PL-C activity increased; furthermore PL-C stimulation by bombesin was deeply impaired by OA.

Early changes of liver phospholipase C activity in rats fed an orotic acid supplemented diet.

In this study of the effect of an orotic-acid (O.A.) diet on the activity of membrane-bound phosphoinositide-specific phospholipase C (PL-C) of rat liver, its enzymatic activity was evaluated in vitro on membranes obtained from the hepatic tissue of male Wistar rats fed a diet containing 1% O.A. for 2 and 5 days and from control rats. The rate of breakdown of labelled phosphatidylinositol-4,5-bisphosphate (Ptdins-P2) added to the isolated membranes was measured both in the absence and in the presence of guanosine-5'-O-thiotriphosphate (GTP gamma S). The enzyme stimulation by bombesin was also analysed. PL-C activity proved to be deeply and early modified by O.A. The basal activity was increased 2 days after feeding on the O.A.-supplemented diet, but the difference from control rats was no more significant after 5 days of this diet. The most interesting changes concerned the response to bombesin; the hormone failed to induce any stimulation of PL-C in O.A.-treated rats after either 2 or 5 days of diet, whereas it nearly doubled Ptdins-P2 breakdown in the liver membranes from control rats. The lack of any stimulation of the phospholipase C by bombesin in O.A.-treated rats indicates a deep impairment of this signal transmission system; its possible causes and consequences are discussed.

Quimioprofilaxia da doença de Chagas: bloqueio da transmissão transfusional por produtos naturais / Chemyprophylaxis of Chagas disease: blockage of blood transfusion transmission by natural products

Em busca da solução para o serio problema da transmissão transfusional da doença de Chagas em nosso meio, realizamos a avaliação de produtos naturais corn atividade tripanosomicida. Os testes "in vitro" foram realizados incubando-se a 4°C, sangue de camundongos contendo ± 10(6)/ ml formas tripomastigotas de Trypanosoma cruzi corn os extratos vegetais. Após diferentes períodos de incubação, frações sangüíneas foram examinadas em microscopia de fase. Os extratos que apresentaram atividade tripanosomicida ate 48 horas de incubação, foram examinados em microscopia eletrônica corn intuito de verificarmos sua toxicidade contra os elementos normais do sangue. Foram testados 242 extratos obtidos de 81 vegetais a 56 demonstraram atividade.

Considering the serius problem of blood transfusion transmission of Chagas disease in our environment, we realized the evalution of natural products against Chagas diseases. The tests were realized "in vitro" by in incubation at 4ºC mouse blood having ± 10(6)/ml of Trypanosoma cruzi, sample "y" and "Colombina" with the plant extracts. After different times of incubation, blood fractions were examined by phase microscopy. The drugs that showed activity until 48 hours of incubation, were examined by electron microscopy to virify the toxicity to blood elements. The tests were realized with 242 extracts from 81 plants and 56 extracts showed activity against T. cruzi.

[Failure of the treatment with penicillin in a case of Neisseria meningitidis meningitis]. / Fracaso del tratamiento con penicilina en un caso de meningitis por Neisseria meningitidis.

Most Neisseria meningitidis are susceptible to penicillin with a minimal inhibitory concentration (MIC) < or = 0.6 mg/L and mortality related to meningococcal meningitis has been low. In recent years, however, N. meningitidis moderately susceptible to penicillin (MIC 0.12-1 mg/L) has been isolated in South Africa, England, USA, and mainly Spain. We report a case of a 16-year old male patient, who was admitted with a diagnosis of meningitis. Because group C N. meningitidis was isolated from cerebrospinal fluid, the patient received 300,000 Ul/Kg penicillin G. Seventy-two hours later, a new lumbar puncture was performed, and N. meningitidis was again isolated from culture. Beta-lactamase activity of the isolate was negative and MIC measurement showed that it was moderately susceptible to penicillin, probably due to modification of a penicillin binding protein. Penicillin G was then discontinued, and the patient was given 50 mg/Kg ceftriaxone. A third lumbar puncture performed on the eighth day after admission showed a negative bacteriological culture. The patient was discharged without neurological sequelae after 14 days of treatment. This case report shows that small changes in N. meningitidis sensitivity may be of clinical relevance.

[Morphological study of the small intestine in rats with experimental zinc deficiency]. / Estudo morfológico do intestino delgado de ratos com carência experimental de zinco.

Rats were maintained 4 weeks on a zinc deficient diet from the time of weaning. A control group received the same basic diet supplemented with zinc. Zinc deficiency, was indicated by poor weight gain, diarrhea, exudative vesicular dermatitis around ears, eyes, nose and extremities, and lowering of blood zinc levels. The morphometric study of the small intestine showed: 1) decreased thickness of the intestinal wall and of the mucosa; 2) significant decrease of the mean villies length and of the mean crypt depth; 3) no alterations in the height of the enterocytes from the middle one third of the villis and in the number of Paneth cells; 4) a decreased mitotic index; 5) a diminished number of epithelial cells living the ville, and 6) a decreased population of intraepithelial lymphocytes, both in the proximal jejunum and distal ileum. These findings are compatible with an impairment of cell replication in the small intestine in experimental zinc deficiency in rats, and allow us to speculate that the diarrhea usually seen in states of zinc malnutrition, at least in part, could be dependent on these changes.

[The content of reduced glutathione in rat liver after poisoning with white phosphorus]. / Contenuto di glutatione ridotto nel fegato di ratto dopo intossicazione con fosforo bianco.

The content of hepatic GSH was evaluated in rats after poisoning with white phosphorus. In addition, liver damage following the administration of the hepatotoxin was assessed by determining hepatic triglyceride accumulation. Experiments in parallel were carried out in an attempt to evaluate the enhanced susceptibility of hepatic tissue to peroxidative decomposition of unsaturated lipids 'in vitro', as measured by the production of TBA-reacting substances. Our data indicate that only in the early stage of intoxication is it possible to detect a slight decrease of GSH content in the liver, while during the subsequent stages the concentration of GSH was unaffected. At 6 hours of intoxication the level of hepatic triglycerides was significantly increased. Pretreatment with GSH was followed by an amelioration of fatty infiltration, but the content of hepatic GSH was unchanged. The production of TBA-reacting products was found enhanced only at 6 hours of intoxication. These results are discussed in relation to the role of lipid peroxidation in liver injury by white phosphorus.

Hepatic damage produced by long-term alcohol consumption in well-nourished rats.

A study of the effect of long-term alcohol consumption on the liver of well-nourished rats is described. Rats fed for 16 weeks on a semipurified diet supplemented with high levels of vitamins and lipotropic factors and alcohol corresponding to 35% of the total caloric intake developed marked fatty changes of the liver. Mild fatty changes were observed in pair-fed controls receiving as isoenergetic equivalent of sucrose instead of alcohol. Intracellular hyaline bodies, corresponding ultrastructurally to giant mitochondria were abundantly found in the hepatocytes of alcoholic rats, while in the controls they were not seen. Te findings in this investigation are postulated to provide further evidence that the long-term intake of alcohol exerts a direct causative role in the pathogenesis of liver damage.