Biomedical subjects
G Triadafilopoulos
Publications and source records attributed to G Triadafilopoulos.
A modification of the quininium resin test for assessing gastric acidity.
BACKGROUND: Gastric acid is an important defence against enteric infection. Studies investigating the relationship between hypochlorhydria and enteric infections or gastric malignancy have been limited by difficulties in the non-invasive measurement of gastric acidity. AIM: To develop a blood test for hypochlorhydria based on the quininium resin test. METHODS: Quininium resin dissociates to liberate free quinine at pH <or= 3.5. Ten fasting adult volunteers ingested 100 mg/kg of quininium resin twice: once before (control) and once after acid suppression with rabeprazole (10 mg b.d. for 3 days). Blood and serum samples were collected at baseline and 45, 60, 75, 90 and 120 min after ingestion. Quinine levels were measured fluorometrically from 100 microL samples after simple extraction. Results obtained by the quininium resin test were compared with gastric juice pH measurements. RESULTS: After quininium resin ingestion, mean quinine levels were lower in the acid-suppressed than in the control condition at all times (P < 0.001). Optimized cut-off values at 90 min post-ingestion yielded 95% accuracy rates in both serum and blood. Quininium resin was well tolerated. CONCLUSIONS: Using blood or serum, the quininium resin test identifies hypochlorhydria accurately and non-invasively. This test may be useful in screening for gastric atrophy and in studies investigating hypochlorhydria.
Reasons for current practices in managing Barrett's esophagus.
We evaluated the reasons for current practices in managing Barrett's esophagus. Using a questionnaire, we assessed the practices and beliefs of 162 Californian gastroenterologists in managing Barrett's esophagus, using descriptive statistics as well as multivariate logistic regression. Out of the 103 respondents, 87% screened for Barrett's esophagus in patients with > 12 months of reflux symptoms, but only 72% believed that screening would improve survival, and 48% believed it to be cost-effective. In total, 98% surveyed patients with long-segment Barrett's esophagus at least biennially (76% thought this would improve survival and 49% believed it to be cost-effective) and 82% surveyed short-segment Barrett's esophagus at least biennially (57% thought this would improve survival and 30% believed it to be cost-effective). Finally, 44% surveyed microscopic intestinal metaplasia at least biennially (26% thought this would improve survival and 11% believed it to be cost-effective). In total, 18% performed endoscopic ablation, whereas 3% referred patients with low-grade dysplasia and 85% referred patients with high-grade dysplasia for esophagectomy. Finally, 81% treated asymptomatic Barrett's esophagus patients with proton pump inhibitors, but only 56% believed that this would reduce the risk of cancer. Logistic regression showed that the only independent factor predictive of surveillance practices was belief in efficacy. Practice patterns tend to be more aggressive than those recommended by recent guidelines and those reported by previous surveys. Medico-legal considerations affect practice substantially.
Decompressive colonoscopy with intracolonic vancomycin administration for the treatment of severe pseudomembranous colitis.
BACKGROUND: We explored the potential of early decompressive colonoscopy with intracolonic vancomycin administration as an adjunctive therapy for severe pseudomembranous Clostridium difficile colitis with ileus and toxic megacolon. METHODS: We reviewed the symptoms, signs, laboratory tests, radiographic findings, and outcomes from the medical records of seven patients who experienced eight episodes of severe pseudomembranous colitis with ileus and toxic megacolon. All seven patients underwent decompressive colonoscopy with intracolonic perfusion of vancomycin. RESULTS: Fever, abdominal pain, diarrhea, abdominal distention, and tenderness were present in all patients. Five of seven patients were comatose, obtunded, or confused, and six of the seven required ventilatory support. The white blood cell count was greater than 16,000 in seven cases (six patients). Colonoscopy showed left-side pseudomembranous colitis in one patient, right-side colitis in one patient, and diffuse pseudomembranous pancolitis in five patients. Two patients were discharged with improvement. Five patients had numerous medical problems leading to their death. Complete resolution of pseudomembranous colitis occurred in four patients. One patient had a partial response, and two patients failed therapy. CONCLUSION: Colonoscopic decompression and intracolonic vancomycin administration in the management of severe, acute, pseudomembranous colitis associated with ileus and toxic megacolon is feasible, safe, and effective in approximately 57% to 71% of cases.
Review article: Barrett's oesophagus, dysplasia and pharmacologic acid suppression.
Barrett's oesophagus, a significant complication of gastro-oesophageal reflux disease (GERD), is the single most important risk factor for oesophageal adenocarcinoma. The strong association between Barrett's oesophagus and chronic GERD suggests that abnormal oesophageal acid exposure plays an important role in this condition. The progression of Barrett's oesophagus from specialized intestinal metaplasia to dysplasia and finally invasive carcinoma is incompletely understood, but increased and disordered proliferation is a key cellular event. In ex vivo organ culture experiments, cell proliferation is increased after exposure to short pulses of acid, whilst proliferation is reduced in Barrett's oesophagus specimens taken from patients with oesophageal acid exposure normalized by antisecretory therapy. In long-term clinical studies, consistent and profound intra-oesophageal acid suppression with proton pump inhibitors decreases cell proliferation and increases differentiation in Barrett's oesophagus, but the clinical importance of such favourable effects on these surrogate markers is not clear. In clinical practice, proton pump inhibitors relieve symptoms and induce partial regression to squamous epithelium, but abnormal oesophageal acid exposure and the risk for dysplasia or adenocarcinoma persist in many patients. The ability of proton pump inhibitors to suppress acid profoundly and consistently may be critical in the long-term management of Barrett's oesophagus.
Upright versus supine reflux in gastroesophageal reflux disease.
BACKGROUND: Postural measures are early recommendations in the management of heartburn, and are aimed at preventing acid reflux through an incompetent lower esophageal sphincter (LES). However, LES incompetence is found in only a minority of patients, and transient LES relaxations, primarily in the upright position, are currently recognized as the main pathophysiological abnormality in gastroesophageal reflux disease (GERD). We investigated the importance of supine acid reflux in patients with GERD. METHODS: Upon review of their clinical, manometric, pH monitoring and endoscopic characteristics, 85 patients with reflux symptoms were classified into three groups: Group A (n=22), consisting of symptomatic patients without esophagitis or pathological reflux; group B (n=38), symptomatic patients with reflux but no endoscopic esophagitis; and group C (n=25), symptomatic patients with both ulcerative or complicated esophagitis and pathological reflux. RESULTS: All groups were similar in age distribution. Groups B and C had a higher prevalence of hiatal hernia and reflux symptoms. Manometry revealed similar LES pressures in groups A and B, but lower LES pressure in group C (P < 0.005). In groups A and B, supine reflux, in terms of percentage of time with pH < 4, was less pronounced than upright reflux (P < 0.0001). In contrast, group C supine reflux was as pronounced as the upright reflux. CONCLUSIONS: The majority of patients reflux in the upright position. Only patients with complicated esophagitis have significant bipositional acid reflux. These findings suggest that unless the patient has severe reflux disease, postural measures may not be indicated.
Acid and bile reflux in Barrett's esophagus: a tale of two evils.
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Radiofrequency energy delivery to the gastroesophageal junction for the treatment of GERD.
BACKGROUND: In this multi-center study, the feasibility, safety, and efficacy of radiofrequency (RF) energy delivery to the gastroesophageal junction (GEJ) for the treatment of gastroesophageal reflux disease (GERD) were investigated. METHODS: Forty-seven patients with classic symptoms of GERD (heartburn and/or regurgitation), a daily anti-secretory medication requirement, and at least partial symptom response to drugs were enrolled. All patients had pathologic esophageal acid exposure by 24-hour pH study, a 2 cm or smaller hiatal hernia, grade 2 or less esophagitis, and no significant dysmotility or dysphagia. RF energy was delivered with a catheter and thermocouple-controlled generator to create submucosal thermal lesions in the muscle of the GEJ. GERD symptoms and quality of life were assessed at 0, 1, 4, and 6 months with the short-form health survey (SF-36). Anti-secretory medications were withdrawn 7 days before each assessment of symptoms and pH/motility study. Medication use, endoscopic findings, esophageal acid exposure, and motility were assessed at 0 and 6 months. RESULTS: Thirty-two men and 15 women underwent treatment. At 6 months there were improvements in the median heartburn score (4 to 1, p < or = 0.0001), GERD score (26 to 7, p < or = 0.0001), satisfaction (1 to 4, p < or = 0.0001), mental SF-36 (46.2 to 55.5, p = 0.01), physical SF-36 (41.1 to 51.9, p < or = 0.0001), and esophageal acid exposure (11.7% to 4.8%, p < or = 0.0001). Esophagitis was present in 25 patients before treatment (15 grade 1 and 10 grade 2) and 8 had esophagitis at 6 months (4 grade 1 and 4 grade 2, p = 0.005). At 6 months, 87% no longer required proton pump inhibitor medication. There was no significant change in median lower esophageal sphincter pressure (14.0 to 12.0 mm Hg, p = 0.19), peristaltic amplitude (64 to 66 mm Hg, p = 0.71), or lower esophageal sphincter length (3.0 to 3.0, p = 0.28). There were 3 self-limited complications (fever for 24 hours, odynophagia lasting for 5 days, and a linear mucosal injury that was healed after 3 weeks). CONCLUSION: RF energy delivery significantly improved GERD symptoms, quality of life, and esophageal acid exposure while eliminating the need for anti-secretory medication in the majority of patients with a heterogeneous spectrum of clinical disease severity but with minimal active esophagitis or hiatal hernia.
Novel adaptation of brush cytology technique for short-term primary culture of squamous and Barrett's esophageal cells.
BACKGROUND: Esophageal disease research is impeded by a paucity of nonmalignant cell lines. Furthermore, culture of primary esophageal cells is difficult because of a lack of cell adhesion and contamination. The aim of this study was to develop a short-term culture method to facilitate cell physiologic studies by using primary esophageal cells. METHODS: By using a cytology brush, squamous and Barrett's epithelial cells were obtained from the esophagus of patients undergoing upper endoscopy. Cells were brushed onto chamber slides and allowed to adhere to the surface. Primary culture media was then added and cells were maintained at 37 degrees C for up to 72 hours. Cell yield and viability were calculated after trypan blue staining. For cell physiologic studies, cells were loaded with pH-sensitive dye BCECF-AM and intracellular pH measured on a dual excitation fluorescence microscope after an ammonium chloride prepulse. At the end of the physiologic experiments, cells were fixed in methanol and acetone and the cell type was verified with cytokeratin immunocytochemistry. RESULTS: Viable human esophageal cells were maintained in culture for up to 72 hours. The cells extruded trypan blue, and BCECF-AM was cleaved to BCECF by an intact cell membrane and permitted intracellular pH measurements. The epithelial cell origin of the cells was confirmed by cytokeratin staining. There was no contamination over the culture period and no overgrowth by lymphocytes or fibroblasts. CONCLUSIONS: This novel adaptation of brush cytology technique enables short-term culture of esophageal cells for in vitro studies. This rapid, simple primary culture technique is suitable for endoscopy and does not require the immediate, time-consuming laboratory techniques.
Temperature-controlled radiofrequency energy delivery for gastroesophageal reflux disease: the Stretta procedure.
BACKGROUND: The delivery of temperature-controlled radiofrequency (RF) energy has been utilized effectively for the treatment of benign prostatic hyperplasia, sleep-disordered breathing, joint laxity, tumors, and cardiac dysrhythmias. The mechanism of action of RF delivery, depending on the specific disease pathophysiology, is related to wound contraction/remodeling or nerve pathway ablation. More recently, temperature-controlled RF energy delivery has been applied for the treatment of gastroesophageal reflux disease (GERD). PURPOSE: To review the use of temperature-controlled RF energy in clinical applications, specifically the safety and efficacy data regarding endoluminal delivery of RF energy for the treatment of GERD (Stretta procedure). RESULTS: Endoluminal RF energy delivery to the gastroesophageal junction for the treatment of GERD is performed using conscious sedation on an outpatient basis. After treatment, medication use is significantly reduced or eliminated at 6 and 12 months, and there is a significant reduction in both the distal and proximal esophageal acid exposure on 24-hour ambulatory pH testing. All studies reviewed demonstrate improvement in GERD symptom scores, heartburn, satisfaction, and quality of life after treatment. There have been no cases of achalasia or stricture resulting from this procedure. Data support both an augmentation of the physical barrier function of the gastroesophageal junction and a reduction in triggering of transient LES relaxations as plausible mechanisms of action for this procedure. CONCLUSION: Endoluminal RF energy delivery has been shown in several studies to be safe and effective for the treatment of GERD and is a promising new technology for this chronic disorder.
Proton pump inhibitors and their drug interactions: an evidence-based approach.
The proton pump inhibitors (PPIs) are the most effective antisecretory agents used to treat acid-related disorders. As such, they are frequently prescribed for patients who are concurrently using other medications. PPIs may interact with other drugs through numerous mechanisms. The most important include competitive inhibition of hepatic cytochrome P (CYP) 450 enzymes involved in drug metabolism, and alteration of the absorption of other drugs via changes in gastric pH levels. Poor metabolizers, who lack CYP2C19, may be particularly predisposed to drug interactions. Although the potential for drug interactions is high, few clinically significant interactions have been reported for the PPIs. Nevertheless, caution is indicated when certain drugs are co-prescribed with these agents. The incidence of clinically significant drug interactions increases proportionately with the number of drugs taken and with the age of the patient. The drug interaction with the greatest clinical importance is the reduction in benzodiazepine clearance by omeprazole.
Is colorectal cancer screening necessary in the preoperative assessment of inguinal herniorrhaphy? A case-control study.
OBJECTIVES: The question of whether patients presenting for inguinal hernia repair require pre-operative assessment for colon cancer has remained unanswered. A case-control study is necessary to assess whether the prevalence of premalignant or malignant colonic lesions is higher in patients presenting with inguinal hernia compared to the general population. METHODS: Between 1990-2000, 614 inguinal herniorrhaphies were performed at the Veterans Affairs Palo Alto Health Care System (VAPAHCS). We retrospectively studied the 149 (24%) patients from this group with no prior history of colonic polyps, malignancy, or gastrointestinal bleeding who had flexible sigmoidoscopy or colonoscopy performed during the peri-operative period. Comparison was made to 149 controls undergoing colonoscopy or sigmoidoscopy during the same time period for colon cancer (CRC) screening. RESULTS: The mean (+/-SEM) patient age was 67 +/- 0.7 (range 31-92) yr in the hernia patients and 66 +/- 0.8 (range 46-93) in the control group (p = 0.7). Eighty-two of the inguinal hernia patients had screening procedures performed preoperatively with a mean time (+/-SEM) of 1.4 +/- 0.14 yr, while endoscopy was performed in the post-operative period for the remaining 67 patients (average time 2.7 +/- 0.2 yr, p < 0.001). More patients underwent colonoscopy in the control group compared to the hernia cohort (p = 0.004). Seven (5%) patients in the hernia group were found to have colorectal cancer compared to six (4%) in the control group (p = 0.8). CONCLUSIONS: This study does not support previously published findings that patients with inguinal hernias are more likely to have premalignant colonic lesions. Patients with inguinal hernias should undergo screening for colon cancer at the same rate as the general population.
Use of a simple symptom questionnaire to predict Barrett's esophagus in patients with symptoms of gastroesophageal reflux.
OBJECTIVE: Accurately predicting Barrett's esophagus (BE) in patients with gastroesophageal reflux disease (GERD) is difficult. Using logistic regression analysis of symptom questionnaire scores we created a model to predict the presence of BE. METHODS: We conducted a logistic regression analysis of symptom data collected prospectively on 517 GERD patients and created a prediction model based on patient gender, age, ethnicity, and symptom severity. RESULTS: There were 337 (65%) males and 180 (35%) females, of whom 99 (19%) had Barrett's esophagus (BE). Multiple logistic regression analysis was performed to determine the predictive ability of gender, age, and ethnicity along with symptoms of heartburn, nocturnal pain, odynophagia, presence of belching, dysphagia, relief of symptoms with food, and nausea. The only significant predictors (at the 0.05 level) were male gender, heartburn, nocturnal pain, and odynophagia (all with positive effects on the presence of BE) and dysphagia (which had a negative effect). A nomogram was produced to show the effect of a given predictor on the probability of having BE in the context of the effects of the other predictors, and to estimate the probability of having BE for a given individual. The mean score (+/-SD) for the BE patients in our sample was 397.4+/-46.2 with a range of 292-530. For the patients without BE, the mean score (+/-SD) was 351.3+/-60.3 with a range of 190 - 528 (p < 0.001). If screening for BE is performed at a score of 375 or more, our model would have a specificity of 63% with a sensitivity of 77% (95% CI 61-86% given the 63% specificity). CONCLUSIONS: By asking seven questions about symptom severity, clinicians may be able to assign a probability to the presence of BE, and thus, determine the need for endoscopy in GERD patients.
Barrett's-related esophageal adenocarcinoma: is chemoprevention a potential option?
OBJECTIVE: Review the rationale behind secondary prevention of Barrett's related esophageal adenocarcinoma and critically appraise the emerging literature regarding prevention of neoplasia in Barrett's esophagus with antisecretory and/or cyclo-oxygenase inhibition therapy. METHODS: The existing English language literature regarding secondary cancer prevention in patients with Barrett's esophagus is reviewed and its potential clinical implications discussed. RESULTS: There is biologic plausibility to pursue "chemoprevention" trials with antisecretory and/or cyclo-oxygenase inhibition therapy in patients with Barrett's esophagus. CONCLUSION: Chemoprevention trials using potent antisecretory therapy coupled with cyclo-oxygenase 2 inhibition are warranted and may provide a means of decreasing the occurrence of cancer and cancer-related mortality in this disease.
Dietary habits and right-sided colonic diverticulosis.
PURPOSE: In Asian populations, there is a high prevalence of right-sided colonic diverticulosis, the cause of which is uncertain. It is suspected that dietary habits may interact with a congenital predilection to cause this condition. To evaluate the relationship between long-term dietary habits and the prevalence of right-sided diverticulosis in the general population, we performed a retrospective case-control study. METHODS: We reviewed the records of 3,105 screening colonoscopies performed on healthy, asymptomatic adults. All cases of right-sided diverticulosis were selected, and a similar number of gender-matched and age-matched controls with negative colonoscopies were randomly sampled from the same cohort. All case and control subjects were interviewed by a single-blinded nurse to establish their dietary habits during the past decade, in addition to other demographic characteristics. Based on consumption frequency, they were assigned to one of three diet classes for each of three food categories of interest: meat, vegetable, and fruit products. Staple foods such as rice were not included. Odds ratios were then calculated using multivariate conditional logistic regression and tests for trend were performed. RESULTS: A total of 86 cases of right-sided diverticulosis were included, whereas 106 controls were randomly selected. There was a marked association between meat consumption frequency and right-sided diverticulosis, with a trend P value of <0.01 and an odds ratio of 24.81 between the most and least frequent consumers of meat products. CONCLUSIONS: The prevalence of right-sided diverticulosis is strongly positively associated with past meat consumption frequency. There is no association with vegetable or fruit consumption frequency, laxative use, supplemental fiber intake, smoking, or family history.
Cyclooxygenase 2 expression in Barrett's esophagus and adenocarcinoma: Ex vivo induction by bile salts and acid exposure.
BACKGROUND & AIMS: Barrett's esophagus (BE) results from chronic, severe gastroesophageal reflux and predisposes to esophageal adenocarcinoma. Cyclooxygenase (COX)-2 is involved in chronic inflammation and epithelial cell growth. We investigated COX-2 expression in BE and esophageal adenocarcinoma to explore a potential relation between COX-2 expression and metaplasia or carcinogenesis. METHODS: Endoscopic mucosal biopsy specimens of Barrett's intestinal metaplasia (n = 30), Barrett's dysplasia (n = 11), and esophageal adenocarcinoma (n = 5) were compared with normal esophagus (n = 46) and duodenum (n = 46) and analyzed by Western blotting and immunohistochemistry. RESULTS: Immunoblots revealed constitutive expression of COX-2 in normal esophagus and duodenum. COX-2 protein expression was significantly higher in patients with Barrett's metaplasia, dysplasia, and adenocarcinoma compared with normal squamous esophageal or columnar duodenal epithelia and was heterogenous in different regions of the BE surface. Immunohistochemistry revealed prominent staining in the glands of BE, dysplasia, and adenocarcinoma and faint staining in the basal layers of squamous esophagus and the surface of the duodenum. In response to pulses of acid or bile salts in an ex vivo organ culture system, COX-2 expression increased significantly in BE tissues, and this effect was attenuated by the selective COX-2 inhibitor NS-398. CONCLUSIONS: The results show COX-2 expression in normal esophagus, which increases significantly in BE and esophageal adenocarcinoma. COX-2 is regulated ex vivo by exposure to acid or bile salts.
Clinical and fiscal impact of lansoprazole intolerance in veterans with gastro-oesophageal reflux disease.
BACKGROUND: Omeprazole was replaced by lansoprazole as the only proton pump inhibitor on the Veterans Affairs (VA) formulary in February 1997. We aimed to assess the clinical and fiscal impact of this conversion at two VA hospitals. METHODS: We identified lansoprazole intolerant patients using pharmacy databases. We reviewed medical records to obtain data regarding reasons for lansoprazole intolerance. The costs of the formulary change and the savings to the VA were calculated. RESULTS: A total of 3833 patients required long-term proton pump inhibitor therapy; 2224 (58%) were started on lansoprazole and 1479 (39%) were converted from omeprazole to lansoprazole. The remaining 130 (3.4%) patients were never converted from omeprazole to lansoprazole. Of the 3833 patients, 325 (8.5%) currently receive omeprazole therapy; of these, 195 out of 3703 (5.3%) patients are true lansoprazole failures; 172 of these 195 patients completed the study. Most (87%) of the lansoprazole intolerant patients received prior omeprazole. Discontinuation of lansoprazole was due to poor symptom control in 69% and/or side-effects (22%) including diarrhoea (10%), abdominal pain (5%), or hives (1%). The 1-year cost of managing lansoprazole failure in 195 patients was $61 690. However, the savings to the VA during the same time period, which totalled $321 360, more than offset the costs associated with the conversion. CONCLUSIONS: Lansoprazole intolerance requiring omeprazole conversion occurred in 5% of veterans on proton pump inhibitor therapy for chronic gastro-oesophageal reflux disease (GERD) symptoms and in 10% of patients with prior omeprazole success. The VA realized substantial cost savings in association with the formulary change.