Temporal summation of repetitive click stimuli

Monaural loudness balances were performed by eight normal-hearing subjects to determine the effect of click repetition rate on loudness sensation. Click trains of 500 msec duration were matched in loudness to a standard 500 msec 1000 Hz tone burst presented at three reference loudness levels (70, 80, and 90 phons). Click trains were presented at repetition rates of 11, 31, 51, and 91 clicks per sec. It was found that click trains at faster repetition rates required lower intensities for judgments of equal loudness sensation. This finding was attributed to the process of temporal loudness summation. The magnitude and nature of the temporal summation process as well as the influence of the reference loudness level are discussed.     

Symptoms, acid exposure and motility in patients with Barrett's esophagus.

INTRODUCTION: Barrett's esophagus, a syndrome in which the squamous mucosa that normally lines the distal esophagus is replaced with columnar epithelium, is found in a small percentage of patients presenting with gastroesophageal reflux disease (GERD). The columnar epithelium may be protective, guarding people afflicted with Barrett's esophagus from experiencing symptoms related to acid reflux. The purpose of this study was to investigate whether people with Barrett's esophagus subjectively experience fewer symptoms or symptoms of decreased severity, despite sustaining greater acid exposure, than those with GERD but without Barrett's syndrome. METHODS: We conducted a chart review of patients with GERD. Criteria for inclusion in the study were esophagogastroscopy, motility testing and a 24-hour pH study. Fifty-eight patients (29 men, 29 women) fulfilled these criteria. The diagnosis of GERD was based on an abnormal 24-hour pH study (DeMeester score). Of these 58 patients, 21 (14 men, 7 women) were found to have histologically confirmed Barrett's esophagus. A questionnaire to assess the key symptoms of GERD was administered, with a severity score ranging from 0 to 3 (3 being the most severe) for each symptom. RESULTS: Patients with Barrett's esophagus experienced symptoms significantly less severe (p < 0.01) than those with GERD. Patients with Barrett's esophagus also had a greater degree of acid exposure as identified by higher DeMeester scores (p = 0.056), longer episodes of acid exposure, a greater number of long episodes (> 5 min) of acid exposure (p = 0.033) and an increased percentage of time when their pH was less than 4. Patients with Barrett's esophagus had decreased resting lower esophageal sphincter tone, and number and amplitude of peristaltic contractions. CONCLUSIONS: For patients with Barrett's esophagus, the columnar epithelium may serve a protective function in guarding against symptoms of acid reflux. This has implications for the diagnosis and management of this condition.     

Canadian Association of General Surgeons Evidence Based Reviews in Surgery. 6. "GERD" as a risk factor for esophageal cancer. Symptomatic gastroesophageal reflux as a risk factor for esophageal adenocarcinoma.

Question: Is gastroesophageal reflux a risk factor for the development of esophageal adenocarcinoma? Design: A case control study. Setting: A population-based study in Sweden between 1994 and 1997. Participants: Cases included all patients with gastric or esophageal adenocarcinoma and half of all patients with esophageal squamous cell cancer, under the age of 80 years and living in Sweden between Dec. 1, 1994, and Dec. 31, 1997. Controls were selected randomly from among persons matched for age (within 10 yr) and sex in the entire Swedish population, through the use of a population register, which is computerized and updated continuously. Assessment of risk factors: Symptomatic reflux was assessed according to the severity of the symptoms (heartburn only, regurgitation only, heartburn and regurgitation combined, nightly symptoms), frequency and duration. Adjustment was made for age, sex, body mass index, smoking history, alcohol ingestion, socioeconomic status, intake of fruit and vegetables, overall energy intake, posture and the degree of physical activity both at work and during leisure. Main outcome measures: Gastric and esophageal adenocarcinoma and esophageal squamous cell cancer. Main results: Among participants with recurrent symptoms of reflux, as compared with those without such symptoms, the odds ratios were 7.7 (95% CI, 5.3–11.4) for development of esophageal adenocarcinoma and 2.0 (95% CI, 1.4–2.9) for adenocarcinoma of the cardia. The more frequent, more severe and longer duration the symptoms of reflux were, the greater was the risk. Among persons with long-standing, severe symptoms of reflux, the odds ratios were 43.5 (95% CI, 18.3–103.5) for development of esophageal adenocarcinoma and 4.4 (95% CI, 1.7–11.0) for adenocarcinoma of the cardia. The risk of esophageal squamous cell carcinoma was not increased with reflux (odds ratio, 1.1; 95% CI, 0.7–1.9). Conclusion: The study identified a strong and probably causal relation between symptomatic reflux as a strong risk factor for esophageal adenocarcinoma and a relatively weak risk factor for adenocarcinoma of the gastric cardia.     

Gastro-oesophageal reflux disease: Medical or surgical treatment? Report of an interactive workshop

Gastroesophageal reflux disease (GERD) is the most common disease of the upper gastrointestinal tract. With the introduction of proton pump inhibitors medical treatment of GERD has been significantly improved. However, the development of laparoscopic antireflux surgery resulted in an increasing interest of surgeons in this disease. An interactive meeting was organized in order to develop an agreement between gastoenterologists and surgeons regarding therapeutic decisions and this is the main topic of this paper.     

The MTT assay for chemosensitivity testing of human tumors of the central nervous system

In this study we assessed the influence of patient- and drug-specific parameters in the short-term MTT-chemosensitivity assay in 150 primary cell cultures derived from human brain tumors. In 45 patients the MTT assay was directly compared with the CFA (Colony Forming Assay). Resistance was 10-20% higher in the MTT assay than in the CFA, but there was a good agreement in both assays, that more malignant gliomas had a higher in vitro chemosensitivity against ACNU and BCNU. Overall the results demonstrate, that there is no uniform correlation between the in vitro chemosensitivity and the histopathological classification of the tumors, which corresponds well to the clinical situation. On the basis of this study we suggest prospective clinical trials with the MTT assay in human brain tumors.