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Biomedical subjects

R B de Oliveira

Publications and source records attributed to R B de Oliveira.

At least 19 recordsLinked to original sources
PubMed2006

Activation of neural cholecystokinin-1 receptors induces relaxation of the isolated rat duodenum which is reduced by nitric oxide synthase inhibitors.

Cholecystokinin (CCK) influences gastrointestinal motility, by acting on central and peripheral receptors. The aim of the present study was to determine whether CCK has any effect on isolated duodenum longitudinal muscle activity and to characterize the mechanisms involved. Isolated segments of the rat proximal duodenum were mounted for the recording of isometric contractions of longitudinal muscle in the presence of atropine and guanethidine. CCK-8S (EC50: 39; 95% CI: 4.1-152 nM) and cerulein (EC50: 58; 95% CI: 18-281 nM) induced a concentration-dependent and tetrodotoxin-sensitive relaxation. Nomeganitro-L-arginine (L-NOARG) reduced CCK-8S- and cerulein-induced relaxation (IC50: 5.2; 95% CI: 2.5-18 microM) in a concentration-dependent manner. The magnitude of 300 nM CCK-8S-induced relaxation was reduced by 100 microM L-NOARG from 73 +/- 5.1 to 19 +/- 3.5% in an L-arginine but not D-arginine preventable manner. The CCK-1 receptor antagonists proglumide, lorglumide and devazepide, but not the CCK-2 receptor antagonist L-365,260, antagonized CCK-8S-induced relaxation in a concentration-dependent manner. These findings suggest that CCK-8S and cerulein activate intrinsic nitrergic nerves acting on CCK-1 receptors in order to cause relaxation of the rat duodenum longitudinal muscle.

Animals↗
PubMed2001

Smooth muscle inclusion bodies in slow transit constipation.

Slow transit constipation (STC) is a disorder of intestinal motility of unknown aetiology. Myopathies, including those characterized by the finding of inclusion bodies, have been described in enteric disorders. Amphophilic inclusion bodies have been reported in the muscularis externa of the colon of STC patients. This study formally tested the hypothesis that these represent a primary muscle disorder, specific to STC. In a systematic, blinded, dual observer qualitative and quantitative analysis, colonic and ileal tissue from patients with STC (n=36) were compared with selected control populations: total colonic aganglionosis (n=10), Chagas' disease (n=6), isolated rectal evacuation disorders (n=6), and a control population of a range of ages (n=80). All sections were stained with haematoxylin and eosin and periodic acid Schiff. Further immunostains were used in an attempt to determine inclusion body composition. Round or ovoid (4-22 microm diameter) amphophilic inclusions increased in number in normal subjects with age. Inclusions were more frequent in idiopathic STC than in age-matched controls or rectal evacuation disorders [ileum (33% vs. 9%), ascending (50% vs. 19%, p<0.05), and sigmoid colon (43% vs. 20%)] and were very frequent in the sigmoid (71%) of patients with STC arising after pelvic surgery. The number of inclusions per unit area was significantly higher in patients with STC (p<0.001). Inclusions were found in all Chagas' patients, but not with aganglionosis. It was not possible to determine inclusion body composition, despite the use of a wide range of conventional and immunostains. This study demonstrates that inclusion body myopathy is identifiable in patients with STC and that it may arise secondary to denervation.

Adult↗
PubMed2001

A physiological manoeuvre to improve the positivity of the gastro-oesophageal reflux scintigraphic test.

One of the best examinations used routinely to detect gastro-oesophageal reflux (GOR) is scintigraphy and attempts are continuously being made to improve the performance of the test. We have tested a new manoeuvre to improve the results. Three hundred and twenty eight patients (190 males and 138 females, aged 1 month to 84 years, average 4.47 years) were studied after a 12 h fast period with 100 MBq of 99Tcm-phytate, 50 ml volume, directly delivered into the stomach in a mixture of orange juice. All patients were strongly suspected of having GOR. Conventional acquisition was done for 20 min, at a rate of one frame every 20 s. In the middle of the examination, small children were put in the upright position and held there for a few seconds or released in a way that allowed movement; adults were asked to stand up and walk a few metres. The test was then continued for the remaining 10 min. The global index of positivity was 64.6% (76 positive cases in the first half of the examination and 134 positive cases only after the manoeuvre). The mean of GOR episodes observed in the positive cases without the manoeuvre was 0.5 per patient, significantly different from the mean of 1.59 noted after the manoeuvre (P<0.01). In 28 cases the manoeuvre increased either the intensity or the frequency of reflux previously detected without it. We believe that this manoeuvre should be performed in all scintigraphic tests aiming to detect GOR. In the present series, the manoeuvre increased the frequency of GOR episodes.

Adolescent↗
PubMed1998

Gastrointestinal manifestations of Chagas' disease.

Chagas' disease is an infectious disease that affects millions of people in Latin America and is increasingly seen outside endemic areas. A substantial number of patients develop gastrointestinal disorders secondary to lesions of the enteric nervous system. The purpose of this article is to review the current knowledge about gastrointestinal manifestations of Chagas' disease, including disorders other than the well-known gross dilations of esophagus and colon.

Bile Duct Diseases↗
PubMed1997

Nonadrenergic-noncholinergic relaxations of isolated circular muscle from South American opossum esophagogastric junction: is nitric oxide the inhibitory mediator?

Nonadrenergic-noncholinergic (NANC) inhibitory nerves are responsible for most of the nerve induced relaxations of gastrointestinal muscle. It has recently been proposed that NANC nerves may release nitric oxide (NO) or a related compound derived from L-arginine. We have recently shown that the South American (SA) opossum is another suitable model to elucidate the mechanism involved in these NANC relaxations. In the present study the effect of NO synthase inhibitors as well as NO inactivators on the NANC-nerve induced relaxations of the circular muscle of the esophagogastric junction (EGJ) of the SA opossum was investigated. It was observed that the NO synthase inhibitors, L-NOARG and L-NAME, caused a concentration-dependent reduction of NANC-nerve induced relaxations which was reversed by L- but not D-arginine. The NO-donors sodium nitroprusside and hydroxilamine as well as NO caused concentration-dependent relaxations of the EGJ circular muscle. In the myenteric plexus of this region, NADPH-diaphorase positive neurons and nerve fibers were observed while in the circular muscle layer only numerous positive fibers were found. The NO inactivators, hydroquinone, pyrogallol and carboxy-PTIO, reduced NO-induced relaxations but failed to affect NANC nerve- and sodium nitroprusside-induced relaxations. Taken together, these findings indicate that NANC nerve induced relaxation of the SA opossum EGJ circular muscle is dependent on neural NO synthase activity and suggest that the neurotransmitter being released is a superoxide resistant molecule, which is unlikely to be the NO radical, or that the activity of NO synthase is required for the release of the actual neurotransmitter rather than for synthesizing the neuromediator.

Adrenergic beta-Agonists↗
PubMed1995

The spectrum of esophageal motor disorders in Chagas' disease.

OBJECTIVE: To determine the patterns of esophageal motility found in patients with Chagas' disease. METHODS: Clinical, manometric, and scintigraphic data were obtained from 43 subjects with positive serological tests for Chagas' disease and nondilated esophagus and 10 patients with Chagasic megaesophagus. RESULTS: Twenty (46.5%) of the seropositive subjects with nondilated esophagus were asymptomatic, and 23 (53.5%) had dysphagia, but only 12 (27.9%) had persistent dysphagia, a feature typical of Chagasic megaesophagus; only two (4.6%) had chest pain. Manometric findings within the seropositive group were: normal motility in 16 subjects, peristaltic multipeaked contractions in three, aperistalsis of the esophagus with relaxing lower esophageal sphincter in nine, and aperistalsis with nonrelaxing lower esophageal sphincter in 15 subjects. All of 10 megaesophagus patients had aperistalsis of the esophagus plus nonrelaxing lower esophageal sphincter. Scintigraphy was as sensitive as manometry in detecting esophageal dysmotility, but the erect scintigraphy was abnormal in subjects with complete aperistalsis only. CONCLUSION: In Chagas' disease, megaesophagus appears to be a disorder at the most severe end of a spectrum encompassing classical achalasia and its milder variants. Other esophageal motility disorders are rare, but normal esophageal function is common.

Adolescent↗
PubMed1992

Clinical characteristics of acute myocardial infarction in patients with Chagas' disease.

From 1981 to 1988, 404 patients at our institution were found to have acute myocardial infarction. Of them, 18 (4%) had a positive fixation test for Chagas' disease. Patient age ranged from 41 to 80 years (median = 59). Eleven patients were males. Eighteen nonchagasic patients were matched by 2 year age intervals and sex with each chagasic patient. Before acute myocardial infarction, there were no differences between chagasic and nonchagasic patients with regard to the proportion of stable angina, unstable angina and coronary risk factors. Atypical chest pain occurred in 8 of 15 (53%) chagasic patients for whom this information was found in the medical records and in 1 of 18 (5%) nonchagasic patients (p = 0.003); dyspnea and palpitations occurred in 6 of 15 (40%) chagasic and 1 of 17 (5%) nonchagasic patients (p = 0.025). There were no differences between chagasic and nonchagasic patients with respect to both clinical characteristics and cardiac complications of acute myocardial infarction. Nonetheless, 4 of 11 (36%) chagasic patients for whom this information was listed in the medical records but none of 16 nonchagasic patients had normal coronary arteries (p = 0.019). Thus, chagasic patients who develop acute myocardial infarction have some peculiarities both in the clinical profile before the acute event and in the anatomy of the coronary arteries.

Adult↗
PubMed1990

Clinical profile of patients with Chagas' disease before and during sustained ventricular tachycardia.

Sustained ventricular tachycardia was diagnosed in 15 patients undergoing ordinary activity with Chagas' disease seen at our Institute from 1978 to 1989. Palpitations were observed in 11 (66%) of the patients, dyspnea in 7 (46%), atypical chest pain in 5 (33%) and syncope in 2 (13%). Cardiac arrhythmia was detected in 4 (26%) on physical examination. The resting electrocardiogram showed premature ventricular contractions in 13 (86%) patients, ST-T changes in 12 (80%), left axis deviation in 9 (60%) and right bundle branch block in 4 (26%). Chest X-rays showed mild cardiomegaly in 8 (53%) and moderate cardiomegaly in 3 (20%) patients. Mild left ventricular dysfunction was detected echocardiographically in 1 (10%), moderate in 3 (30%) and severe in 1 (10%) of the 10 patients studied. During sustained ventricular tachycardia, dyspnea was found in 7 of 15 (46%) patients, palpitations in 6 (40%), atypical chest pain in 6 (40%), syncope in 1 (6%), systemic arterial hypotension in 3 (20%) and cardiogenic shock in 2 (13%). The electrocardiographic findings were as follows: mean heart rate was 201 bpm; mean QRS lengthening was 0.16 sec; right bundle branch block plus right axis deviation was seen in 5 of 15 (33%) patients; right bundle branch block plus left axis deviation in 4 (26%); and a positive concordance of all precordial leads in 5 (33%) patients. Based on these findings, we conclude that the majority of patients with Chagas' disease who develop sustained ventricular tachycardia do not have severe myocardial disease, show an uncommon electrocardiographic pattern of this arrhythmia, and most importantly, have a benign clinical course.

Adult↗
PubMed1988

Effect of isosorbide dinitrate and atropine on the lower esophageal sphincter pressure in Chagasic patients.

The effect of isosorbide dinitrate (5 mg, sublingually) and of atropine (12 micrograms/kg i.v.) on the lower esophageal sphincter pressure of chagasic patients with esophageal involvement and of control subjects was studied by the manometric method. The pressure was measured at 5 minute intervals for 60 minutes after drug administration. When the effect of isosorbide dinitrate was studied, basal sphincter pressure (mean +/- SEM) was 15.3 +/- 1.9 mmHg in chagasic patients (N = 15) and 25.4 +/- 5.6 mmHg in controls (N = 9) (P greater than 0.05). Isosorbide dinitrate reduced sphincter pressure between 10 and 20 minutes and at 40 minutes in controls, and froM 5 to 60 minutes in chagasics (P less than 0.05). The reduction was more intense in chagasics throughout the time of measurement (P less than 0.05). When the effect of atropine was studied, basal sphincter pressure was 20.6 +/- 1.8 mmHg in chagasic patients (N = 14) and 23.7 +/- 2.5 mmHg in controls (N = 9) (P greater than 0.05). Atropine reduced sphincter pressure both in chagasics and controls, but more intensely so in controls during the first 30 minutes of the study (P less than 0.05). The action of the musculature itself may be the main factor in the maintenance of sphincter pressure in chagasics, with secondary participation of the cholinergic excitatory system.

Administration, Sublingual↗
PubMed1985

Dysphagia lusoria and segmental aperistalsis in the upper third of the esophagus.

An aperistaltic zone located in the upper third of the esophagus was present in a young woman with dysphagia, who had undergone surgical treatment for dysphagia lusoria 3 months before. The segmental absence of contraction in the upper third of the esophagus was the most probable cause for the persistence of dysphagia, and could have resulted from damage related to compression or to surgical intervention in the area.

Adult↗
PubMed1984

The effect of a segmental gastrectomy with proximal gastric vagotomy on gastric secretion and gastric emptying.

Gastric acid secretory responses to graded doses of pentagastrin were measured in duodenal ulcer patients before and after either proximal gastric vagotomy (17 patients) or proximal gastric vagotomy associated with a segmental gastrectomy (11 patients). Calculated maximal output of acid and responsiveness of the acid-secreting cells to pentagastrin were reduced by both operations; after surgery, maximal acid output was lower in the proximal gastric vagotomy plus segmental gastrectomy group than in the proximal gastric vagotomy group. Gastric emptying of a liquid meal was assessed before and after either proximal vagotomy (13 patients) or proximal gastric vagotomy plus segmental gastrectomy (9 patients). The early phase of emptying was equally accelerated by both operations, and at later stages the emptying was only slightly, but not significantly, faster following proximal gastric vagotomy associated with segmental gastrectomy.

Adolescent↗
PubMedDate not supplied

An AC biosusceptometer to study gastric emptying.

A simple AC susceptometer was developed to study the gastric emptying when test meals labeled with 10% of a harmless magnetic tracer were ingested. The instrument allows the determination of T 1/2 of the stomach emptying with good precision compared to measurements with gamma camera and 99m Tc in the test meal.

Adult↗