PubMed Health⌕ Search

Biomedical subjects

S Keren

Publications and source records attributed to S Keren.

11 recordsLinked to original sources
PubMed2003

Distributed three-dimensional fiber Bragg grating refractometer for biochemical sensing.

We demonstrate a three-dimensional (3-D) distributed refractometer that measures refractive index in a small volume. The sensor is based on an evanescent-wave fiber Bragg grating that is interrogated by low-coherence spectral interferometry. The measurement can be performed on a short time scale without the need for a mechanical scan. The new sensor was used to simultaneously measure glucose concentration in several droplets along a single sensor and to interrogate the time-dependent evaporation process of a water droplet. The new measurement technique might enable novel 3-D distributed sensors to be developed and multiple discrete measurements to be made in a small volume.

Journal Article↗
PubMed1995

The role of Helicobacter pylori in children with recurrent abdominal pain.

OBJECTIVES: Our major goals in this study were to determine the prevalence of Helicobacter pylori among Israeli children with recurrent abdominal pain and to establish whether a link exists between eradication of Helicobacter pylori and the recovery from abdominal pain. The alternative target was to examine whether the serological test can replace endoscopy in children. METHODS: Upper gastrointestinal endoscopy was performed in 80 children with recurrent abdominal pain. During endoscopy, antral biopsies were taken and sent for histological and bacteriological examination. RESULTS: The prevalence of H. pylori, which was indicated by Gram stain and urease test, was 54%. The positive cases were treated with bismuth combined with amoxycillin and metronidazole. Two months after completion of the treatment, 34 patients were reexamined. Twenty-nine of them (85%) became symptom free, and five (15%) remained symptomatic. These five children were retreated, and they also became symptom free. Eight months after completion of treatment, all 34 patients were reexamined and found to be asymptomatic. CONCLUSIONS: We found a high prevalence of H. pylori (54%) among Israeli children with recurrent abdominal pain; we also found that symptoms were effectively and significantly reduced by the eradication of H. pylori. The endoscopic examination cannot be replaced by serological test.

Abdominal Pain↗
PubMed1992

Solid swallowing versus water swallowing: manometric study of dysphagia.

The aim of the study was to investigate whether a soft solid bolus can induce abnormal manometric patterns in patients with dysphagia and normal standard manometry. The study group comprised 12 normal volunteers and 22 patients with dysphagia. Manometry was performed using 10 wet swallows followed by 10 swallows of marshmallow. The results show: (1) in normal subjects the mean contraction amplitude is significantly greater (P less than 0.035) and the velocity of propagation significantly slower (P less than 0.003) for soft solid swallows compared with wet swallows; (2) in normal subjects there are fewer abnormal contractions after soft solid swallows than after wet swallows; (3) in 15 patients, soft solid swallows induced non-peristaltic contractions and/or contractions of extreme amplitude and/or duration that were not observed after wet swallows; (4) in patients, the probability of inducing abnormal contractions after soft solid swallows is significantly greater than after wet swallows (P less than 0.0001). We conclude that soft solid swallowing is useful in the study of patients with dysphagia.

Adult↗
PubMed1992

[Marshmallow for investigating functional disturbances of the esophageal body].

Manometric studies using water boluses do not always demonstrate disturbances in esophageal motility. We tested the use of a marshmallow bolus to induce abnormal manometric patterns in patients with dysphagia in whom manometric studies using water boluses were normal or nearly so. The study group included 12 normal volunteers and 22 patients with dysphagia and nearly normal manometric studies. Pressure was recorded along the esophageal body using 10 "wet" swallows followed by 10 "solid" swallows of marshmallow. In normal subjects there were fewer abnormal contractions after solid swallows than after wet swallows. In 15 patients solid swallows induced abnormal motility patterns which were not observed after wet swallows. The probability of inducing abnormal contractions in patients after solid swallows is significantly greater than after wet swallows (p < 0.0001). Solid swallowing is therefore useful in evaluating functional disturbances of the esophagus in patients with dysphagia.

Adult↗
PubMed1992

Screening for colorectal neoplasia: a multicenter study in Israel.

We report the design and results of the first Israeli multicenter screening program for colorectal neoplasia. The screening protocol comprised a risk questionnaire, fecal occult blood testing, flexible sigmoidoscopy and colonoscopy. A total of 5,601 individuals were screened in five medical centers, 55% being asymptomatic with low or average risk. Colorectal tumors were found in 12.3% of screenees, the majority being adenomas. The risk for large bowel neoplasia was greatest in persons with a personal history of colorectal neoplasia (neoplasia rate 473.2/10(3)) and was increased in those with inflammatory bowel disease, a family history of colorectal tumor, or past history of cured breast cancer. European-born Jews had a 50% greater risk than non-European-born Jews. Persons at high risk were more likely to return for repeat screening than those at low or average risk. However, approximately 15% of persons at high risk actually thought that they were of average risk. Fecal occult blood testing was markedly less reliable than flexible sigmoidoscopy and had a false-negative rate of 84.4%. The results demonstrate that existing medical facilities in Israel can be used to screen at least those individuals with increased risk for colorectal neoplasia.

Adenoma↗
PubMed1988

Studies of manometric abnormalities of the rectoanal region during defecation in constipated and soiling children: modification through biofeedback therapy.

Anorectal manometry was performed on 12 normal children and 18 patients suffering from constipation and soiling. In both groups, the results of the rectoanal inhibitory reflex and the squeezing anal pressure were similar. The pressure recording in all the normal children showed that the anal canal relaxed during defecation. Fourteen (78%) constipated children closed the anal canal while straining by contracting the anal sphincter. This paradoxical contraction appears to be the cause of chronic constipation. Twelve children with paradoxical anal closure were treated by biofeedback therapy. The results show that all these children were successfully conditioned to relax their anal sphincter during defecation. This therapy improved their bowel habits and relieved them from constipation and soiling. It is proposed that the paradoxical anal closure itself is the result of a self-conditioning process. In this process, the patient learns to paradoxically contract the external anal sphincter in response to the urge and the act of defecation. Biofeedback therapy seems to be the appropriate treatment in such cases.

Anal Canal↗
PubMed1981

Effect of nitrates on LOS pressure in achalasia: a potential therapeutic aid.

The effect of a long-acting nitrate, isosorbide dinitrate (ID) 5 mg sublingually, on the lower oesophageal sphincter was tested in 24 patients with achalasia. The drug caused a reduction in LOS pressure in all cases. The mean LOS pressure fell from 46.32.7 mmHg to 15.31.8 mmHg (p less than 0.01). The pressure began to drop after several minutes, reaching its lowest levels after 15 minutes. This measured manometric effect lasted for 60 minutes or more in 10 patients studied. The reported clinic effect lasted for two to three hours, permitting the ingestion of a meal. Twenty-three patients were followed clinically for two to 19 months while receiving the drug three times daily before meals. Nineteen reported a marked to complete relief of dysphagia. Five of these patients had previous pneumatic dilatation, cardiomyotomy, or both, and had recurrence at time of study. Side-effect, mainly headache, were reported in eight patients. In six this was alleviated by substituting oral isosorbide dinitrate, 10 mg. Two patients became refractory to treatment after two to six months. The potential role of long-acting nitrates in the treatment of achalasia has yet to be established.

Adult↗