Recommendations for the reopening and activity resumption of the neurogastroenterology units in the face of the COVID-19 pandemic. Position of the Sociedad Latinoamericana de Neurogastroenterología. / Recomendaciones para la reapertura y reinicio de actividades de las Unidades de Neurogastroenterología ante la pandemia por COVID-19. Posicionamiento de la Sociedad Latinoamericana de Neurogastroenterología.

The COVID-19 pandemic has forced the establishment of preventive measures against contagion during the performance of diagnostic and therapeutic tests in gastroenterology. Digestive tract motility tests involve an intermediate and elevated risk for the transmission of COVID-19 infection. Given their elective or non-urgent indication in the majority of cases, we recommend postponing those tests until significant control of the infection rate in each Latin American country has been achieved during the pandemic. When the health authorities allow the return to normality, and in the absence of an effective treatment for or preventive vaccine against COVID-19 infection, we recommend a strict protocol for classifying patients according to their infectious-contagious status through the appropriate use of tests for the detection of the virus and the immune response to it, and the following of protective measures by the healthcare personnel to prevent contagion during the performance of a gastrointestinal motility test.

Action of cisapride on rat colonic secretion.

The stimulating effect of cisapride on the motility of the digestive tract is well known. However, there are only a few studies on the influence of this drug on the absorptive or secretory activity of the colonic mucosa. In the present study, the ability of cisapride to alter the mural transport of water and electrolytes in the colon and its effects on mucus secretion and albumin permeation were studied. The effects of cisapride on the rat colon in vivo were studied under different conditions, by means of an instillation of sodium acetate solution at pH 6.9, which induced absorption of water and electrolytes, and in two models of colonic secretion, one employing the instillation of an acetic acid solution at pH 2.9 and the other, an intravenous infusion of 5-hydroxytryptamine (serotonin) 45 micrograms.kg-1.min-1 together with intracolonic instillation of sodium acetate. Cisapride (i.v.), at a dose of 0.32 mg.kg-1, in rats whose colon was instilled with sodium acetate (pH 6.9) induced an increase in sodium absorption and a reduction in water absorption. Cisapride (i.v.), at doses of 0.32, 0.64 and 1.0 mg.kg-1, inhibited the secretion of water, Na+, Cl-, and mucus and the permeation of albumin induced by acetic acid instillation or by serotonin infusion. It is concluded that the effect of cisapride on the colonic mucosa varies in accordance with the functional mucosal conditions and that this action may be of clinical importance.

[Influence of sodium butyrate intake on murine colonic carcinogenesis]. / Influencia de la ingesta de butirato de sodio en la carcinogénesis colónica murina.

The role of short chain fatty acids (SCFA) in murine colonic carcinogenesis (MCC) has not yet been clarified. In rats, Freeman et al have reported an increased number of colonic tumors induced with dimethylhydrazine (DMH) and sodium butyrate in drinking water. On the other hand, Deschner et al showed that tributyrin intake did not increase MCC induced with azoxymethane. Both of them have reported high levels of fecal butyric acid with sodium butyrate and tributyrin intake. Although salt intake has been positively associated with colorectal cancer some authors do not support this association. We have evaluated the influence of right hemicolectomy (RH) (right colon as main source of SCFA) and the intake of 2%-pH 7 sodium butyrate (S.BUT) and 4 g/l sodium chloride (S.CHL) in drinking water, in MCC. Forty eight male Wistar rats weighing 150 g were divided into 4 groups: RH, S.BUT, S.CHL, control (C). Half of the animals received weekly DMH 20 mg/kg subcutaneously for 12 weeks. Necropsy was performed after 6 months. We have determined fecal SCFA content by gas chromatography. Neoplasm was present in 70% of rats treated with DMH. The number of animals with tumors was: RH 4/6, S.BUT 4/6, S.CHL 3/5, C 6/6. Tumor frequency was: RH 1.17 +/- 0.48, S.BUT 1.50 +/- 0.76, S.CHL 1.20 +/- 0.49, C 1.50 +/- 0.22. S.BUT group, treated with DMH, presented a lower butyric acid concentration (p < 0.05) in comparison with other groups. We have no explanation for this finding; gastric absorption of sodium butyrate may be an important factor.(ABSTRACT TRUNCATED AT 250 WORDS)

[Gastric solitary plasmacytoma associated with +Helicobacter pylori infection]. / Plasmocitoma solitario gástrico asociado a infección por Helicobacter pylori.

Solitary gastric plasmacitomas are infrequent tumors. They account for 5% of the extramedullary plasmacitomas. We report an unusual case in a 14 years old boy. The patient has had gastric symptoms for 2 years prior to an endoscopic examination. A fungating, ulcerated lesion was observed in the antrum. The biopsies showed a monoclonal, Lambda positive, diffuse, plasmocitic proliferation infiltrating the mucosa. Also a moderate number of Helicobacter pylori were identified in the gastric pits and numerous lymphoid follicules were observed in the deep portion of the mucosa. In view of the presence of HP infection the patient was treated with Orneprazole and Clarithromycin. Endoscopic examination and biopsies performed 3 and 5 months later showed a complete remission of the gastric lesion. At the time of this report the patient is in good physical condition, has recovered his weight and has grown 5 cm. Differential diagnosis with plasmo limpho in chronic gastritis and with lympheicitic lymphoma with plasmocitoid features had to be done. The macroscopic appearance of the gastric lesion, the absence of other inflammatory cells and monoclonality of the plasmocitic infiltration ruled out chronic gastritis. The negative staining for CD 20 as well as the abscence of lymphoid cells in the mucosal infiltrate give support: to the diagnosis of plasmocitoma. The close association between gastric MALT lymphoma and HP infection has been reported as well as its regression after antibiotic treatment for its erradication. In our review of the literature we failed to find any references to the association of HP with gastric plasmocitoma nor to its regression after antibiotic therapy.

Effect of loperamide and bisacodyl on intestinal transit time, fecal weight and short chain fatty acid excretion in the rat.

We analyzed the effect of drugs that modify the colonic motility on rat intestinal transit time (ITT) (measured with radiopaque markers), fecal weight (FW) and fecal concentration of short chain fatty acids (FSCFA) (assayed by gas liquid chromatography), over a four-week period. Bisacodyl was used to accelerate and Loperamide to retard the intestinal transit in rats maintained on a conventional diet. The first and 3rd week were drug-free control periods. The mean values of these periods were: ITT = 28.9h +/- 1.9 FW: 9.2 +/- 1.2 g/24 h and FSCFA = 60.6 +/- 17.9 mmol/g. After loperamide administration, we observed an increase in the mean ITT as compared to the control period (40.4 +/- 8.0h) and decrease in FW (4.8 +/- 3.6 g/24h) and in FSCFA = 32.2 +/- 5.6 mmol/g). After bisacodyl administration, we found a shorter ITT in relation to controls (24.8 +/- 2.5h), and increases in FW (27.5 +/- 3.6g/24h) and in FSCFA (108.2 +/- 39.9 mmol/g). There was a negative correlation between ITT and FW (R = 0.67 p less than 0.01) and a positive correlation between total SCFA concentration and FW (R = 0.71 p less than 0.01). The concentration of acetic, propionic and butyric acids increased with progressive increments in fecal weight, whereas concentrations of isovaleric and caproic acids decreased. The results of this study show that the FW and the FSCFA may be influenced by modifications in the intestinal transit time.

[The effect of different lactic acid isomers in the colon of rats]. / La acción de los diferentes isómeros del acido láctico en el colón de la rata.

Depending on quantity and/or quality, the presence of lactic acid in the colonic lumen may be associated with metabolic damage of the colon. The influence exerted on the rat colon by the different isomers and racemic of the lactic acid, used at two extreme dilutions (20 and 100 mEq/l), has been the subject of study in this paper. The modifications on pH, water and electrolytes are associated with the absorptive/secretory action of the colonic wall. In addition, a study has been made on the influence of lactic acid on the colonic mucus and albumin permeation. Histopathologic studies of the caecum and left colon have been performed. There is a different colonic wall behaviour for each of the different isomers of the lactic and its racemic; a larger absorption of water, Na+ and Cl- for the D (-) isomer at a low concentration; its behaviour is completely opposite at high concentration. The final pH is higher when the D (-) isomer takes part; comparing the different isomers, there are small variations as far as albumin permeation is concerned. At high concentration there is a decline in Cl- absorption. The high percentage of erosions that take place especially in the caecum, where L (+) isomer can be found at high concentration, it is remarkable. The present observations suggest that the presence of lactic acid in (the) ulcerative colitis deserves great attention, especially in about the quantity and quality in which the acid can be found.

[Do the physical characteristics of radiopaque markers modify the results of the measurement of colonic transit time?]. / Los caracteres físicos de los Marcadores Radiopacos modifican los resultados de la medición del tiempo de tránsito colónico?

UNLABELLED: This study was performed in 15 healthy control subjects (8 males- age 23-70 and 7 females age 20-74) as a way to compare the total and segmental colonic transit time with two different type of radiopaque markers. One type of markers was 3 mm cut sections of a radiopaque polietilene 14 French Levine tube, with a medium weight of 64.3 mg and a specific gravity (SG) of 1.28. The other type were 7 mm lenticular insoluble barium (lentils) with medium weight of 231 mg and a SG of 1.87. Each subject ingested 20 markers of each type with the breakfast and front and profile plain films of the abdomen were taken 24 and 48 hs after. The total colonic transit time for the polietilene markers was 17.7 hs and 27.3 hs for the barium type (BM) (p < 0.001). The segmental transit time for right colon was 2.4 hs (PM) and 9.7 hs (PM) and 9.7 hs (BM) (p < 0.001) in the left colon 9.5 hs (PM) and 11.3 hs (BM) and in rectoanun 5.9 hs (BM) with no statistical significance. CONCLUSION: the physical characteristics of the radiopaque markers can modify the results of the colonic transit times.

Stimulation of inflammatory mediators secretion by chemotactic peptides in rat colitis model.

Colonic inflammation was produced in rats by chemotactic peptides acting on polymorphonuclear leucocytes. Instillation during one hour of formylated tripeptide: formylmethionyl-leucyl-phenylalanine (FMLP) and a tetrapeptide: alanine-glycine-sefine-glutamine (AGSG) into rat colon caused erosions and exulcerations. Neutrophils increased secondary to instillation, predominantly with FMLP, and mucus depletion was marked in the cecum. Chloride ion secretion and mucosal permeability were significatively greater in the colonic lumen with the chemotactic peptides. Histamine and serotonin concentration were greater in the colonic fluid in animals treated with the peptides. These observations could suggest that the presence of chemotactic peptides at the colonic lumen produce changes at the mucosal wall, that would participate in generation and perpetuation of the colonic inflammation.

[Post-sectional antral peptic ulcer and antrofundic re-anastomosis in rats (manifestation of a probable antrofundic neuroendocrine center)]. / Ulcera péptica antral postsección y reanastomosis antrofúndica en la rata (puesta de manifiesto de un probable centro neuroendócrino antrofúndico).

The antrum-fundic section and re-anastomosis (AESR), liberates, in Wistar male rats, genuine antral peptic ulcers. They start within 20 days. They are progressive evolution, penetrating into all gastric walls. Between 7 and 8 months, they involve near organs (spleen, liver, pancreas) and produce a great inflammatory reaction of the peripancreatic ganglions. The antral peptic ulcer is induced if the gastric lesser curvature's nerves are sectioned and a concomitant pyloroplasty is done or not. The gastric hemisection, if anterior or posterior, break out the peptic ulcer only on the same side of the antrum-fundic interruption. In all this situations, except in cases of concomitant pyloroplasty, it is proved a pronounced and significantly increase of the gastric (g/kg), but not pancreatic index. In the AFSR series with nervous section on the lesser curvature and without pyloroplasty, the percentage of antral peptic ulcers in 56%. It is postulated the probably existence, at an antrum-fundic level, of a neuroendocrine center. Its nullification or disturbance by the section and re-anastomosis procedure could generate the antral ulcer and other histologic changes (increase of the "G" cells, hyperplasia of the parietal, ECL and "A like" cells) by one or various hypothetical ways: 1. Direct action, nullifying the normal blocking function of somatostative over the "G" cells and or parietal cells. 2. Disturbing or nullifying the motor pump effect of the gastric antrum, and on this way, enhancing the duodenum-gastric reflux with all know deleterious effects of the bile in the antrum particularly in an acid milieu. 3. Modifying, in the opposite direction, the sensitivity by one hand, of the "G" cells mass and by the other one, of the parietal, ECL and "A like" cells. The depression of the fundic sensitivity will induce the hyperplasia of the "G" cells, the hypersecretion of gastrin and, "a posteriori", all the secretory effects and trophic characteristic of it. 4. Disturbing the prostaglandins secretion, perhaps through a deficit of the nervous innervation, with the resulting epiphenomenon of a cytoprotection deficit mediated through the mucus and bicarbonate production. It is probably that the proposed physiopathogenic mechanism are associated and that the final result, the antral peptic ulcer is the consequence of an increase of the aggressive factors (acid, bile) and a concomitant depression of the defensive factors (cytoprotection), starting normally by the prostaglandins through the mucus and bicarbonate secretion.

Colonic motility in man: features in normal subjects and in patients with chronic idiopathic constipation.

The human colon is still a relatively unknown viscus, especially concerning its motor activity. However, in recent years, techniques have been perfected that allow a better understanding of colonic motility, especially through prolonged recording periods. In this way, it has been demonstrated that the viscus contracts according to a circadian trend, is responsive to physiological stimuli (meals, sleep), and features high amplitude, propulsive contractions that are part of the complex dynamic of the defecatory process. These physiological properties and their alterations in patients with chronic idiopathic constipation are reviewed in this article.

Organic anions induce colinic secretion.

Experiments were conducted by instilling test solutions into the cleaned colon of anesthetized rats. Isotonic test solutions at an acid (2.9% or neutral (7.0) pH and containing acetic acid or acetate ions were used. At the lower pH, acetic acid was absorbed well absorbed and the colon absorbed fluid. The secretory effect could not be reproduced by hydrochloric acid solutions at pH 2.9. Fluid secretion induced by acetic acid was associated with discharge of mucus from goblet cells. The interference of colonic absorption by acetic acid might be important in some diarrheal diseases.

Does secretin influence rat colonic absorption and secretion?

In rats, a secretin (Jorpes) intravenous infusion superimposed on an intracolonic sodium acetate perfusion elicits, with respect to control values, a significant depression of Na+ absorption (0.16 mEq./h-0.00 mEq./h.) and mucus secretion (230-40 mg.). When the hormone is superimposed upon an intracolonic infusion of acetic acid, mucus secretion is also significantly inhibited (790-340 mg.). The influence of secretin on organic anion movement was pH related. At pH values of 7.0, absorption was unchanged (0.34--0.33 mEq./h.), at pH values of 2.9, absorption was significantly reduced (0.67-0.41 mEq./h). The secretin impairment of colonic mucus secretion could influence the transport of watersoluble (Na+) and lipid soluble (acetic acid) substances, probably through changes at the "unstirred layer" level.

Pirenzepine as anti-inflammatory drug in a model of experimental colitis in rat.

Pirenzepine has been widely used for the treatment of gastric and duodenal ulcer. In this work we have proved that this drug could prevent the inflammatory reaction induced in the colon with an intraluminal stimuli as the acetic acid. These data suggest the cholinergic participation in the inflammatory colonic response.