The aim of the present study was to develop a classifier able to discriminate between healthy controls and dyspeptic patients by analysis of their electrogastrograms. Fifty-six electrogastrograms were analyzed, corresponding to 42 dyspeptic patients and 14 healthy controls. The original signals were subsampled, filtered and divided into the pre-, post-, and prandial stages. A time-frequency transformation based on wavelets was used to extract the signal characteristics, and a special selection procedure based on correlation was used to reduce their number. The analysis was carried out by evaluating different neural network structures to classify the wavelet coefficients into two groups (healthy subjects and dyspeptic patients). The optimization process of the classifier led to a linear model. A dimension reduction that resulted in only 25% of uncorrelated electrogastrogram characteristics gave 24 inputs for the classifier. The prandial stage gave the most significant results. Under these conditions, the classifier achieved 78.6% sensitivity, 92.9% specificity, and an error of 17.9 ± 6% (with a 95% confidence level). These data show that it is possible to establish significant differences between patients and normal controls when time-frequency characteristics are extracted from an electrogastrogram, with an adequate component reduction, outperforming the results obtained with classical Fourier analysis. These findings can contribute to increasing our understanding of the pathophysiological mechanisms involved in functional dyspepsia and perhaps to improving the pharmacological treatment of functional dyspeptic patients.

Background: Recent studies have described a high percentage of small intestinal bacterial overgrowth (SIBO) in patients with irritable bowel syndrome (IBS). However, the prevalence of SIBO has not been well established in other functional disorders. Aim: To evaluate the prevalence of SIBO in patients with different functional gastrointestinal disorders (FGID). Material and methods: Patients with FGID completed a self-administered questionnaire providing information to diagnose functional disorders on the basis of Rome II criteria. SIBO was assessed using a standardized lactulose breath test. A basal value of breath hydrogen (H2) >20 ppm and/or two lectures of HZ values >20 ppm during the first 60 minutes were considered suggestive of SIBO. Results: We studied 367 patients with a mean age of 50 years (87% females). Of these, 225 had IBS (45 constipation predominant, 121 diarrhea predominant and 59 alternating type), 33 had functional constipation, 83 had functional bloating and 26 had functional diarrhea. SIBO was found in 76% of patients with IBS, 73% of those with functional constipation, 69% of those with functional diarrhea and 68% of those with functional bloating. Conclusions: This study confirms a high percentage of SIBO in patients with IBS and other FGID. The eradication of SIBO should be considered as a therapeutic tool in these patients

Background: Helicobacter pylori is a pathogenic bacterium that infects a significant number of individuals. At present, therapeutic strategies to eradicate this bacterium depend on our knowledge of its resistance to antimicrobials. Aims: To evaluate the primary resistance of H pylori to metronidazole (Mtz), clarithromycin (Cla), and tetracycline (Tet) in symptomatic out-patients. Material and Methods: Fifty independent isolates of H pylori were obtained by endoscopy-assisted gastric biopsy from patients attending the University of Chile Clinical Hospital, that previously had not been treated with an eradication regime against this bacterium. The minimal inhibitory concentration of each antimicrobial was determined by agar dilution method. Results: Forty five and 27% of the isolates were found to be resistant to Mtz and Tet, respectively; the majority of these resistant isolates were from patients older than 21 years. Twenty percent of isolates were resistant to Cla; these were distributed evenly among different ages. Thirty two percent of the isolates were resistant to two or more of the antimicrobials. Conclusions: The high frequency of naturally occurring, antimicrobial-resistant strains of H pylori poses a national and world-wide problem for public health

Background: Many patients with irritable bowel syndrome (IBS) have lowered sensory thresholds to rectal distention when compared to control subjects, a phenomenon called visceral hypersensitivity. Aim: To investigate the usefulness of a rectal barostat as a diagnostic tool in IBS and if there are differences in visceral hypersensitivity in different groups of IBS patients. Patients and Methods: Ten healthy subjects and 19 IBS patients, defined using Rome II criteria (12 with constipation, three with diarrhea and four alternating between diarrhea and constipation), were studied. Sequential isobaric rectal distentions, from 2 mmHg up to a maximal pressure of 52 mmHg or when the patients reported pain, were carried out. Visceral hypersensitivity was defined as a pain threshold under 38 mmHg. Results: Only 26% of IBS patients had visceral hypersensitivity (16% and 43% of patients with IBS and constipation and IBS and diarrhea or alternating symptoms, respectively, p =NS). Pain threshold in controls, patients with IBS and constipation and patients with IBS and diarrhea or alternating symptoms was 43.8±6.6, 45.3±9.2 and 40.8±9.2 mmHg, respectively (p =NS). Conclusions: Our results do not support the usefulness of the electronic rectal barostat as a diagnostic method to diagnose IBS

Background: Studies in patients with chronic severe constipation, suggest the presence of a diffuse motor disorder of the gastrointestinal tract. Aim: To investigate small bowel motor activity in a group of patients with severe constipation. Material and Methods: Forty three patients (age range 13 to 70 years, 40 women) with severe constipation referred to our motility laboratory, where studied. Ten had a previous colectomy. Radiological examinations showed a megacolon in 30 and dilatation of small intestinal loops in nine; the remaining X rays studies were normal. Small intestinal motility was studied using perfused catheters and external transducers. Results: Ten patients had normal motor recordings. Eight patients showed a neuropathic disorder characterized by a continuous irregular pattern of contractions of normal amplitude, with absence of phase III of the migrating motor complex (MMC). Sixteen presented a normal MMC associated to a decreased amplitude of contractions (Miopatic disorder). Nine showed both types of motor disorders (Mixed pattern). Normal radiological findings were more commonly associated to normal manometric recordings. By contrast, an altered motor activity, mainly of myopathic and mixed type motor disorder, was observed in all patients with dilated small intestinal and colonic loops. Conclusions: The presence of small intestinal motor disorders was a frequent finding in this selected group of patients with chronic constipation

Background: Esophageal candidiasis is associated with conditions that cause an immune depression. It is a defining disease for AIDS, is observed in poorly controlled diabetics, in patients with renal or hepatic failure, in patients with cancer and in subjects using medications causing immunosuppression or broad spectrum antimicrobials. Aim: To report the features of 10 immunocompetent patients with esophageal candidiasis. Patients and methods: Six males and four females aged between 48 and 82 years, without conditions associated with immunosuppression, in whom an esophageal candidiasis was found on an upper gastrointestinal endoscopy. Delayed skin hypersensitivity to eight antigens, Iymphocyte subpopulations, yeast phagocytosis and neutrophil chemotaxis were measured. Results: Six patients had a low CD4 Iymphocyte count and seven had a low CD8 count. Seven patients were anergic on skin hypersensitivity challenge. Yeast phagocytosis was abnormal in one patient and neutrophil chemotaxis was abnormal in two. Humoral immunity was normal in all subjects. All patients were treated with oral fluconazole in doses of 150 mg/day for 14 days, with complete resolution of candidiasis in all. Conclusions: Patients with esophageal candidiasis, have frequent alterations of cellular immunity, that must be diagnosed and treated

Serum antibodies against Trypanosoma Cruzi have been observed in 19% of the Chilean population. Marked differences in organ involvement have been reported in patients with Chagas disease. Chagas disease is rarely an aetiological factor for achalasia in Chile, which is different from reports in other countries of South America. In contrast, a high incidence of megacolon among these patients have been reported. Aim: To study the incidence of gastric and small intestinal motor disorders among these patients and their relationship to esophageal and colon motility disorders. Patients and Methods: We studied 18 patients, 12 women (mean age 45 years); with positive antibodies against T Cruzi. Seven had radiological evidence of megacolon and no one had radiological or manometric evidence for achalasia. Non specific motor esophageal abnormalities were found in 11 patients. Nine had an abnormal electrocardiogram, suggesting a myocardial disease. A questionnaire for gastrointestinal symptoms, an electrogastrography and a small intestinal motility study, were performed in each patient. Results: All patients had evidences of abnormalities in at least one segment of the digestive tract. Twelve patients had an abnormal electrogastrographic study, with bradygastria as the most common finding. Nine had an abnormal small intestinal manometry with a myophatic pattern evidenced by a decreased amplitude of contractions (18.5±3 mmHg). Also an increased number of clustered contractions was observed. Conclusions: Gastric dysrhythmias and small intestinal motor abnormalities are frequently associated to non specific esophageal motor disorders and megacolon in patients with Chagas disease (Rev Méd Chile 2004; 132: 939-4)

Background: Small intestinal bacterial overgrowth generates endogenous ethanol production both in experimental animals and humans. Patients with cirrhosis have small intestinal bacterial overgrowth, but endogenous ethanol production has not been studied in them. Aim: To investigate endogenou ethanol production in patients with cirrhosis, altered intestinal motility and small intestinal bacterial overgrowth. Patients and methods: Eight patients with cirrhosis of different etiologies and altered gastrointestinal motility, consisting in changes in the migrating motor complex, were studied. All had also small intestinal bacterial overgrowth, measured by means of the H2 breath test with lactulose. Plasma ethanol levels were measured by gas liquid chromatography in fasting conditions and 120 min after a carbohydrate rich meal. Results: In fasting conditions, no patient had endogenous ethanol production. Alter the meal, ethanol in concentrations of 11.3 and 8.2 mg/del were detected in two patients. Negligible amounts of ethanol were detected in 4 patients and two patients had undetectable alcohol levels. Conclusions: A low endogenous production of ethanol was demonstrated in six of eight patients with cirrhosis (Rev Méd Chile 2002; 130: 1329-34)

Background: Gastric electrical activity can be accurately recorded and analyzed by cutaneous electrogastrography. Different types of abnormalities have been described in a variety of disorders. Aim: To analyze a group of asymptomatic subjects and assess the prevalence and patterns of dysrrhythmias in patients with type 1 and 2 diabetes and patients with functional dyspepsia. Patients and methods: One hundred subjects were studied (32 male, mean age 45 years old, 10 asymptomatic, 11 type 1 diabetics, 22 type 2 diabetics and 57 subjects with functional gastrointestinal disturbances). Gastric myoelectrical activity was recorded using surface electrogastrography for 1 hour in the fasting state and 1 hour after a test meal (350 kcal). Results: The electrogastrogram was normal in 90% of asymptomatic controls. It was abnormal in 64% of type 1 diabetic patients, in 55.5% of type 2 diabetic patients and in 61% of patients with functional dyspepsia. Different types of dysrrhythmias were observed in each group. Conclusions: Electrogastrography might define a subgroup of patients with electrical rhythm disturbances, that may have a different approach to treatment than patients with normal gastric electrical activity (Rev Méd Chile 2002; 130: 1209-16 ).

Background: Abnormal small bowel motility, observed in liver cirrhosis, can be reversed with cisapride. Since both cisapride and liver disease are associated with prolonged QT interval, the possibility of adverse cardiovascular effects might be expected with cisapride treatment in these patients. Aim: To evaluate QT interval and other electrocardiographic changes during long term treatment with cisapride in cirrhotic patients. Patients and methods: Forty seven cirrhotic patients were studied. Electrocardiogram was recorded and the QT interval corrected according to Bazzett’s formula was determined (normal value <0.44 s). Seventeen patients were treated with cisapride, 10 mg tid for seven months and electrocardiographic controls were performed at the end of the treatment. Results: The mean corrected QT interval was 0.46 ± 0.03 s (range 0.4-0.53). 34 patients (64%) had QTc prolongation (0.47 ± 0,02 s). Statistically significant higher values of QTc were observed in patients at Child Pugh stage B and C compared to stage A. No statistically significant difference according to the etiology of liver disease, were observed. No changes in mean QTc duration were observed during cisapride treatment. Conclusions: In spite that a prolonged QTc was a frequent finding in our serie of selected patients, no cardiovascular adverse effects were observed with long term cisapride treatment. (Rev Méd Chile 2000; 128: 847-52).

Background: Small intestinal manometry is a relatively simple technique. However, its use is usually limited to very few centers and mainly related to research studies. Aim: To report our experience with small intestinal motility studies in a group of normal controls and patients with symptoms suggesting a gastrointestinal motor disorder. Patients and methods: Seventy three studies were performed in 71 subjects: 18 asymptomatic controls and 55 patients presenting with symptoms characterized by abdominal pain, vomiting, bloating, constipation and diarrhea. In 33 patients the same symptoms remained without diagnosis, in spite of extensive laboratory studies. In 10 of these, dilated small intestinal loops were observed and intestinal pseudoobstruction was suspected. Twenty two additional patients with systemic disorders such as scleroderma, diabetes and previous vagotomies, were studied. Motility was assessed by means of perfused catheters connected to external transducers for a mean lapse of 280 min. Results: An abnormal pattern of small intestinal motility suggesting neuropathic, myopathic or a mixed disorder was observed in 76% of all studied patients, with the exception of patients with scleroderma, in whom only myopathic and mixed alterations were observed. In 82% of patients, the results of manometry were useful for the management of the clinical condition. Conclusions: small intestinal manometry is a relatively simple technique that, when used in selected groups of patients, provides useful information for clinical management.