Biomedical subjects

W Shahin

Publications and source records attributed to W Shahin.

12 recordsLinked to original sources

PubMed2000

Role of cGMP as a mediator of nerve-induced motor functions of the opossum esophagus.

Stimulation of esophageal nerves produces biphasic relaxation of the lower esophageal sphincter (LES) and an off response of circular esophageal muscle. Previously, we proposed that cGMP mediates nerve-induced hyperpolarization of circular LES muscle but not LES relaxation. These experiments explore whether cGMP mediates LES relaxation or the off response. Strips of muscle from the opossum esophagus and LES were connected to force-displacement transducers, placed in tissue baths containing oxygenated Krebs solution at 37 degrees C, and stimulated by an electrical field. 1H-[1,2, 4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), a selective inhibitor of guanylyl cyclase, antagonized the off response, shortened its latency, and blocked the first phase of LES relaxation. ODQ also antagonized LES relaxation by exogenous nitric oxide (NO) but not relaxations by vasoactive intestinal polypeptide (VIP). Part of the nerve-induced LES relaxation and the off response appear to be mediated by the second messenger cGMP. These studies indicate that VIP-induced LES relaxation is not mediated by cGMP and therefore do not support the hypothesis that VIP produces LES relaxation by causing the generation of NO.

Animals↗

PubMed1999

Esophageal cancer and Barrett's esophagus. How to approach surveillance, treatment, and palliation.

Esophageal cancer is an increasingly common problem with poor survival rates in patients who present with symptoms. The underlying cause for the progressive rise in the incidence of this cancer remains to be determined. Reducing mortality to requires either early identification of patients or prevention for progression from Barrett's esophagus to cancer. Significant questions remain regarding the cost effectiveness of endoscopic and nonendoscopic methods of surveillance. For local esophageal cancer, the traditional approach has been surgical resection. Radiation therapy is sometimes used alone, but chemotherapy alone is not helpful. Combination therapy consisting of chemotherapy along with surgery or radiation may be the best choice. A new option being tried in disease limited to the mucosa is ablation of neoplastic tissue with endoscopic techniques. Treatment of advanced-stage esophageal cancer is limited and may be hampered by the presence of micrometastatic disease. Morbidity and quality-of-life issues need to be considered and discussed with patients, given the current short survival time of most patients with esophageal cancer.

Adenocarcinoma↗

PubMed1974