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Biomedical subjects

F E Silverstein

Publications and source records attributed to F E Silverstein.

At least 37 records · Page 2Linked to original sources
PubMed1989

Experimental evaluation of an endoscopic ultrasound probe: in vitro and in vivo canine studies.

We developed an endoscopic echo probe that can be passed via the biopsy channel of a flexible fiberoptic or video endoscope with a 3.5-mm channel. The probe moves along the gastrointestinal wall under direct endoscopic vision. The translational scanning action is sensed by a position potentiometer and combines with the ultrasonic B-mode echoes to produce a cross-sectional image of the wall. The system uses an ultrasound frequency of 20 MHz to produce high-resolution images. The device was used to image canine gastrointestinal tissue in vitro and in vivo during endoscopy. Ultrasound images of the gut wall correlate with histologic structure. This probe overcomes some of the problems associated with the combined ultrasound endoscopes now in use. Use of the probe with video endoscopy allows the endoscopic and ultrasound images to be displayed side by side, simplifying coordination of application of the two techniques.

Animals↗
PubMed1989

A 20-MHz ultrasound system for imaging the intestinal wall.

An ultrasound system has been developed which uses high-frequency (20 MHz) ultrasound to provide high-resolution images of tissue. The system provides 0.21-mm range and 0.65-mm lateral resolution. The transducer aperture size is 1.8 mm maximum. Miniature probes have been developed which can image via the biopsy channels of standard fiberoptic endoscopes as well as probes for imaging in vitro. A commercially available video "frame grabber" is used in conjunction with a standard microcomputer for image acquisition. This allows images to be displayed and recorded on standard television equipment and be stored and manipulated digitally. The features of the system allow in vivo imaging, in vitro imaging after resection, and histological images of the same tissue region to be acquired and compared. This method is particularly useful in learning how to correctly interpret ultrasonic images of the intestinal wall. The use of 20 MHz is advantageous in achieving excellent resolution and small size probes. The system provides a unique approach to imaging the intestinal wall.

Analog-Digital Conversion↗
PubMed1989

Misoprostol reduces gastroduodenal injury from one week of aspirin: an endoscopic study.

Misoprostol is a synthetic prostaglandin E1 analogue that inhibits gastric acid production and may augment mucosal defense. A double-blind trial examined the effect of misoprostol on the endoscopic appearance of gastroduodenum at the end of 1 wk of aspirin ingestion. One hundred thirty healthy subjects were randomized to take either 50, 100, or 200 micrograms of misoprostol, or placebo along with 975 mg of aspirin four times daily. Fewer subjects developed acute endoscopic gastric ulcers in the group taking any dose of misoprostol compared with the placebo group (1% vs. 43%). No subject taking the 100- or 200-micrograms dose of misoprostol developed an acute endoscopic duodenal ulcer compared with 13% of subjects taking placebo (p less than 0.05). Significantly fewer subjects developed gastric erosions and significantly fewer subjects developed duodenal erosions in each of the three groups taking misoprostol compared with the placebo group (p less than 0.01). There were fewer subjects with a gastric erosion (p less than 0.05) and fewer subjects with a duodenal erosion (p less than 0.05) in the group taking the 200-micrograms dose compared with the group taking the 50-micrograms dose of misoprostol. Gastrointestinal symptoms causing a modification in usual activities were infrequent but there was significantly more diarrhea in the 200-micrograms misoprostol group. There was no correlation between endoscopic scores and symptoms in any group. We conclude that misoprostol can protect the normal gastroduodenum from acute ulceration and reduce the chance of erosion after 1 wk of aspirin ingestion.

Adolescent↗
PubMed1988

Role of H2-receptor blockers in the prevention of gastric injury resulting from nonsteroidal anti-inflammatory agents.

Nonsteroidal anti-inflammatory drugs (NSAIDs) can produce injury to the gastric and duodenal mucosa. The histamine (H2)-receptor blocker cimetidine was studied to determine whether protection of the gastric mucosa of normal volunteers could be provided against a single dose of aspirin, 1,300 mg. Gastric mucosal injury was assessed with gastroscopy performed two hours after aspirin intake. Three liquid cimetidine doses were administered over 24 hours prior to the aspirin dose, the last dose one hour before the aspirin. The 200-mg and 400-mg doses of cimetidine protected a sufficient number of subjects to warrant further study. In the second study, these two doses were further examined to determine whether three doses were necessary and whether the final dose could be coadministered with the aspirin instead of one hour before. Concomitant administration of a single dose of cimetidine with aspirin was found to protect the gastric mucosa from aspirin damage as effectively as the other cimetidine regimens employed. A final, double-blind comparison of cimetidine, 200 mg, with placebo administered with the aspirin, 1,300 mg, confirmed that cimetidine protected the gastric mucosa from the hemorrhagic effects of aspirin.

Aspirin↗
PubMed1987

Gastric protection by misoprostol against 1,300 mg of aspirin. An endoscopic dose-response study.

Misoprostol at a dose of 200 micrograms inhibits gastric acid secretion and protects the gastric mucosa against the injurious effects of a single 1,300-mg dose of aspirin. The purpose of this study was to determine whether lower subantisecretory doses of misoprostol protect the gastric mucosa in this single-dose aspirin model. Protection was defined as no more than 10 hemorrhagic spots and no more than two hemorrhagic streaks. A total of 140 men participated in the two phases of the study. In the first phase, groups of 10 subjects each received placebo or misoprostol in doses of 200 micrograms, 100 micrograms, 50 micrograms, or 25 micrograms in a double-blind design. All misoprostol doses protected 50 to 70 percent of subjects as compared with 20 percent of subjects in the placebo group. To expand the number of observations, 90 additional subjects in groups of 30 each were evaluated after receiving misoprostol 50 micrograms or 25 micrograms or placebo. Misoprostol 50 micrograms protected 14 of 30 subjects (47 percent), 25 micrograms protected 11 of 30 (37 percent), and placebo protected six of 30 (20 percent). The dose-response trend was statistically significant (p less than 0.05). It is concluded that misoprostol protects the gastric mucosa against a single 1,300-mg dose of aspirin and that there is a significant dose-response relationship.

Adolescent↗
PubMed1987

Reduction of endoscopically assessed acute aspirin-induced gastric mucosal injury with cimetidine.

We studied the influence of cimetidine on the gastroscopically visible effects of a single 1296-mg dose of aspirin. An initial dose-response study in 48 subjects showed that 200- and 400-mg doses of cimetidine conferred a sufficient reduction in gastric mucosal injury to warrant further study. A second study showed that coadministration of a single 200- or 400-mg cimetidine tablet with the aspirin conferred the same degree of injury reduction as when cimetidine was given before the aspirin. Reduction in mucosal injury by a 200-mg cimetidine tablet, coadministered with four aspirin tablets, was then compared to placebo in a double-blind trial. A reduction of mucosal injury was observed in 14 of 20 (70%) subjects receiving cimetidine and 0 of 10 subjects receiving placebo (P less than 0.001). Two hundred milligrams of cimetidine is therefore a rational dose for further studies of the reduction of chronic aspirin-induced gastric mucosal injury.

Acute Disease↗
PubMed1987

Cross-sectional imaging method. A system to compare ultrasound, computed tomography, and magnetic resonance with histologic findings.

Studies comparing imaging modalities require a precise knowledge of the type and location of tissue structures. When comparing cross-sectional techniques such as ultrasound, computed tomography, and magnetic resonance imaging, the images must be obtained through the same tissue section that is examined histologically. An experimental system that permits comparison of these modalities with histologic sections of precisely corresponding tissue is described. Application in 30 gastrointestinal tissue specimens shows a high degree of correspondence between cross-sectional images and histologic sections. This method should be useful in tissue imaging research for anatomic correlation and for comparisons between imaging modalities.

Digestive System↗
PubMed1987

Colorectal neoplasms: accuracy of US in demonstrating the depth of invasion.

Six normal and 16 neoplastic colorectal specimens were examined with 8.5-MHz ultrasound (US). An articulated system facilitated precise spatial correlation between US and histologic sections. Images were blindly interpreted and then compared with histologic results. All six normal specimen showed five distinct echo layers and were distinguished from neoplastic specimens by all the observers. The central echogenic layer, corresponding to the submucosa, is useful in determining the depth of origin of a neoplasm and the presence of submucosal invasion. US had an accuracy of 92.5% in demonstrating invasion of the submucosa and 77% for invasion of the muscularis externa. For mucosal neoplasms with invasion through the muscularis externa and extension into the subserosal tissues, nearly 90% of US interpretations were correct. High-frequency US may be useful in determining the depth of invasion of mucosal tumors with respect to the submucosa and in differentiating mucosal from extramural masses.

Biopsy↗
PubMed1986

Inflammatory polyposis two years after ischemic colon injury.

Inflammatory polyps occur in association with ulcerative colitis, Crohn's disease, and other inflammatory diseases of the colon. The occurrence of inflammatory polyps following ischemic colitis has not been well documented. A 49-year-old man suffered complications of hypoperfusion, including renal insufficiency, hepatic failure, shock lung, and ischemic colitis following emergent repair of an acute aortic dissection. Although the renal, hepatic, and pulmonary complications resolved, the patient continued to experience intermittent bloody diarrhea more than two years after his initial presentation. Barium enema and colonoscopy revealed numerous pedunculated polyps in the descending and sigmoid colon. Histopathology of the polyps removed by snare electrocautery showed them to be inflammatory polyps. We believe these are the sequelae of chronic ischemic colitis.

Colitis↗
PubMed1986

Gastric protection by misoprostol against 1300 mg of aspirin. An endoscopic study.

Misoprostol, a synthetic prostaglandin E1 analog, is being evaluated in the treatment of peptic ulcer. It has been reported to have both antisecretory and cytoprotective properties. In this placebo-controlled, double-blind study, pretreatment with 200-micrograms doses of misoprostol was evaluated in the prevention of gastric injury caused by aspirin. Five oral doses of misoprostol or placebo were administered over 24 hr followed by a single oral 1296-mg dose of aspirin 30 min after the fifth dose of test agent. Two hours later the gastric mucosa was examined with a small-caliber fiberendoscope. Protection was defined as no more than 10 petechiae and no more than two hemorrhagic streaks in the gastric mucosa. Twenty of 30 (67%) subjects who received misoprostol was protected, whereas only one of 30 (3%) subjects receiving placebo was protected. The difference between the effects of misoprostol and placebo was highly significant (P less than 0.001). We concluded that five 200-micrograms doses of misoprostol given over 24 hr protects the gastric mucosa from the injurious effect of a single dose of aspirin.

Adolescent↗
PubMed1984

Prevention of acute aspirin-induced gastric mucosal injury by 15-R-15 methyl prostaglandin E2: an endoscopic study.

The deleterious effects of aspirin on gastric mucosa have been well documented in experimental and clinical studies. Prostaglandins offer a potential method by which this injury may be prevented. In these studies, we developed a single-dose endoscopic assay system of aspirin-induced gastric mucosal injury in normal volunteers. With this system, 27 of 30 volunteers (90%) demonstrated severe mucosal injury after ingestion of aspirin. Subsequently, we evaluated whether pretreatment with 15-R-15 methyl prostaglandin E2 prevented severe injury after ingestion of aspirin. Following an initial dose-response study, a double-blind crossover trial was performed using pretreatment with placebo or with 10-micrograms doses of 15-R-15 methyl prostaglandin E2 for 24 h before treatment with aspirin. The results of this trial indicate that prostaglandin pretreatment significantly prevented the occurrence of endoscopically visible severe gastric mucosal injury after single-dose aspirin administration.

Adolescent↗
PubMed1982

Double duct sign: reassessed significance in ERCP.

The double duct sign, defined as an abnormality of both the pancreatic duct and the contiguous part of intrapancreatic common bile duct, was found in 52 of 1180 patients studied by endoscopic retrograde cholangiopancreatography. Thirty patients were proved to have pancreatic malignancy and 22, benign pancreatic disease. Specific ductal characteristics found to indicate a malignant process were ductal obstruction, especially of the common bile duct, close proximity of the biductal lesions, a short stenotic segment of the common bile duct removed from the papilla, an abrupt, irregular transition from normal to stenotic or obstructed duct. Ductal characteristics suggesting a benign process were long length of common bile duct stenosis, calcium deposits, pseudocyst formation, and ectasia of pancreatic ductal branches central to the main duct lesion. This analysis indicates that the double duct sign per se is not disease specific, but when other ductal characteristics are assessed as a component of this finding, the ability to differentiate benign from malignant pancreatic disease is enhanced.

Adenocarcinoma↗
PubMed1981

Upper gastrointestinal tract bleeding. Predisposing factors, diagnosis, and therapy.

The mortality from upper gastrointestinal (GI) tract bleeding has remained constant at 10% during the past 40 years. Many drugs may precipitate upper GI tract bleeding by disrupting the gastric mucosal barrier. Aspirin-induced injury to the gastric mucosa and GI tract bleeding have been documented in many studies; some of the mechanisms involved are known, but others are still being investigated. An approach to the bleeding patient is suggested; initial resuscitation, history taking, physical examination, determination of bleeding levels, and diagnostic procedures to determine the cause of bleeding are reviewed. Also described are available therapies for GI tract bleeding-gastric lavage, drug therapy, endoscopic control, electrocautery, thermal probe, tissue adhesive, and laser photocoagulation. The merits of the argon laser and the neodymium-yttrium aluminum garnet laser (both still in experimental stages) are described and compared. No pharmacologic or endoscopic therapies for upper GI tract bleeding have been proved effective.

Angiography↗
PubMed1981

National ASGE survey on upper gastrointestinal bleeding: complications of endoscopy.

Data about the risks of upper endoscopy in patients with upper gastrointestinal bleeding was gathered as part of a prospective national survey of the ASGE membership. Endoscopic complications occurred in 21 of 2320 endoscopies (0.9%). These included 12 major (perforation, aspiration, bleeding) and 9 minor (mucosal tear, medication reaction, transient cardiac or pulmonary episode) complications. There were 3 deaths attributable to major complications of the procedure. These fatalities all occurred in patients with severe major underlying illnesses. Although these results indicate a higher complication rate than earlier retrospective ASGE surveys on endoscopy, they are comparable to other available data about the risks of endoscopy in the specific group of patients with upper gastrointestinal bleeding.

Adult↗