Search PubMed⌕ Search

Biomedical subjects

B Krevsky

Publications and source records attributed to B Krevsky.

At least 55 records · Page 3Linked to original sources
PubMed1990

Failure of (+)-naloxone to accelerate feline colonic transit.

To determine whether the colonic transit accelerating effect of (-)-naloxone (0.3 mg/kg, i.m.) is due to an action at opioid receptors or a direct pharmacologic effect, its enantiomer, (+)-naloxone (0.3 mg/kg, i.m.), was administered to cats and compared to saline control using colonic transit scintigraphy. Transit was not accelerated by (+)-naloxone. The effects of naloxone on colonic transit are thus stereospecific, and are probably mediated by opioid receptors.

Animals↗
PubMed1990

Feline cholescintigraphy. Studies on role of cholecystokinin in regulation of gallbladder function.

Quantitative cholescintigraphy using technetium-99m-disofenin was employed to study the kinetics of gallbladder filling and emptying in cats. The radionuclide rapidly visualizes the gallbladder, with activity continuing to rise during the 60 minutes after injection. The gallbladder emptied in a dose-response manner to the intravenous administration of the octapeptide of cholecystokinin (CCK-OP). An infusion of 10 ng/kg/min of CCK-OP resulted in 75% emptying of the gallbladder at 30 min compared to control. This was significantly greater emptying than with an infusion of either 0.1 or 1.0 ng/kg/min. After administration of a fatty meal, the 30-min gallbladder emptying was 73% of control, similar to the response to CCK-OP at a dose of 10 ng/kg/min. Intravenous administration of 1 mg/kg of L-364,718 (a CCK-receptor antagonist) completely inhibited the gallbladder response to a fatty meal but had no effect on gallbladder filling in the fasting state. These results suggest that feline cholescintigraphy can be used for the quantitative study of gallbladder emptying. While CCK appears to be the primary modulator of gallbladder contraction after a fatty meal, no influence of CCK was detected in the interdigestive (fasting) state.

Animals↗
PubMed1989

Effects of morphine and naloxone on feline colonic transit.

The effects of endogenous and exogenous opioid substances on feline colonic transit were evaluated using colonic transit scintigraphy. Naloxone (0.3 mg/kg, i.m.) accelerated emptying of the cecum and ascending colon, and filling of the transverse colon. Endogenous opioid peptides thus appear to play a significant role in the regulation of colonic transit. At a moderate dose of morphine (0.1 mg/kg, i.m.), cecum and ascending colon transit was accelerated, while at a larger dose (1.0 mg/kg, i.m.) morphine had no effect. Since naloxone, a relatively nonspecific opioid antagonist, and morphine, a principally mu opioid receptor agonist, both accelerate proximal colonic transit, a decelerating role for at least one of the other opioid receptors is inferred.

Animals↗
PubMed1989

Scintigraphic evaluation of gastric emptying: are radiolabeled solids necessary?

A standard, dual-isotope meal (Tc-99m-egg sandwich and In-111 DTPA in water) was administered to 14 normal volunteers and 37 patients, who had not undergone gastric surgery, to determine if the emptying characteristics of the liquid phase alone could accurately predict delayed solid emptying. Delayed gastric emptying was defined clinically as a solid half-emptying time more than two standard deviations greater than the mean for normal volunteers. Linear regression analysis was performed on the natural logarithm of liquid fractional retention at each time interval to yield a slope and y-intercept for each subject. There was no significant difference (0.6 less than P less than 0.8) between volunteers and patients with normal solid emptying for the liquid slope. In patients who exhibited delayed gastric emptying for solids, the liquid slopes were significantly different from the normal values (P less than .001). There was a high correlation of liquid slope to solid half-emptying time in all patients and volunteers (r = -0.80, P less than .001). Comparison of the liquid slope measurement to solid half-emptying time criteria revealed a sensitivity of 96%, a specificity of 100%, and a predictive value of 100% for the slope test. These results suggest that delayed gastric emptying can be accurately detected with a liquid-solid meal using only a single-liquid label.

Adult↗
PubMed1989

Cisapride accelerates colonic transit in constipated patients with colonic inertia.

A double-blind cross-over trial of oral cisapride 10 mg before meals and placebo was performed to determine its effects on colonic transit in patients with severe idiopathic constipation. Nine patients with less than 3 spontaneous bowel movements/wk were studied. After passing a tube to the cecum, 50 muCi of 111In-DTPA were instilled into the cecum and followed for 48 h using colonic transit scintigraphy. In the group as a whole, cisapride had little effect on transit. The patients were then divided into two groups based on transit: functional rectosigmoid obstruction (FRSO) and colonic inertia (CI). In the CI group, cisapride accelerated the half emptying time of the cecum and ascending colon from 2.50 to 1.21 h (p less than 0.05). The progression of the geometric center was also faster after cisapride in CI. In FRSO, the geometric center was unchanged by cisapride except at 48 h. Cisapride thus has a prokinetic effect on colonic transit in patients with severe idiopathic constipation, colonic inertia subtype. It may be a useful agent in the treatment of this group of patients.

Adult↗
PubMed1989

Patterns of colonic transit in chronic idiopathic constipation.

Rectosigmoid motility, anal manometry, and radiopaque marker studies have suggested the presence of several patterns of altered colonic transit in patients with chronic idiopathic constipation. Colonic transit scintigraphy was used to evaluate 23 constipated patients. After oral passage of a tube to the cecum, 50 microCi of 111In-diethylenetriaminepentaaceticacid (111In-DTPA) were instilled, and abdominal images were obtained for 48 h with a gamma camera. The 95% confidence limit for the geometric center in normals at 24 h was used as a criterion to differentiate patients with colonic inertia from those with functional rectosigmoid obstruction. In patients with functional rectosigmoid obstruction, colonic transit was essentially normal. In colonic inertia, transit was delayed in the cecum and ascending colon, hepatic flexure, and transverse colon. These two distinct patterns of colonic transit may have different pathogenetic and therapeutic implications.

Adult↗
PubMed1988

Role of opiate receptors in the regulation of colonic transit.

The effects of morphine and the opiate antagonist naloxone on human colonic transit were investigated. In a crossover, double-blind fashion, two groups of 6 normal volunteers were studied using colonic transit scintigraphy during the administration of a test drug or control. The test drugs were morphine (0.1 mg/kg every 6 h s.c.) or naloxone (0.8 mg every 6 h s.c.); control was saline (1 ml every 6 h s.c.). Morphine significantly delayed transit in the cecum and ascending colon (p less than 0.05), slowed the progression of the geometric center (p less than 0.01), and decreased the number of bowel movements per 48 h (p less than 0.005). Naloxone accelerated transit in the transverse colon and rectosigmoid colon (p less than 0.05) and accelerated the progression of the geometric center (p less than 0.05), but had no effect on the number of bowel movements per 48 h (p greater than 0.05). These results suggest that narcotic analgesics may cause constipation in part by slowing colonic transit in the proximal colon and by inhibiting defecation. Acceleration of transit by naloxone suggests that endogenous opiate peptides may play an inhibitory role in the regulation of human colonic transit.

Adult↗
PubMed1988

Biphasic nature of gastric emptying.

The existence of a lag phase during the gastric emptying of solid foods is controversial. It has been hypothesised that among other early events, the stomach requires a period of time to process solid food to particles small enough to be handled as a liquid. At present no standardised curve fitting techniques exist for the characterisation and quantification of the lag phase or the emptying rate of solids and liquids. We have evaluated the ability of a modified power exponential function to define the emptying parameters of two different solid meals. Dual labelled meals were administered to 24 normal volunteers. The subjects received meals consisting of either Tc-99m in vivo labelled chicken liver or Tc-99m-egg, which have different densities, and In-111-DTPA in water. The emptying curves were biphasic in nature. For solids, this represented an initial delay in emptying or lag phase followed by an equilibrium emptying phase characterised by a constant rate of emptying. The curves were analysed using a modified power exponential function of the form y(t) = 1-(1-e-kt)beta, where y(t) is the fractional meal retention at time t, k is the gastric emptying rate in min-1, and beta is the extrapolated y-intercept from the terminal portion of the curve. The length of the lag phase and half-emptying time increased with solid food density (31 +/- 8 min and 77.6 +/- 11.2 min for egg and 62 +/- 16 min and 94.1 +/- 14.2 min for chicken liver, respectively). After the lag phase, both solids had similar emptying rates, and these rates were identical to those of the liquids. In vitro experiments indicated that the egg meal disintegrated much more rapidly than the chicken liver under mechanical agitation in gastric juice, lending further support to the hypothesis that the initial lag in emptying of solid food is due to the processing of food into particles small enough to pass the pylorus. We conclude that the modified power exponential model permits characterisation of the biphasic nature of gastric emptying allowing for quantification of the lag phase and the rate of emptying for both solids and liquids.

Adult↗
PubMed1988

Quantitative measurement of feline colonic transit.

Colonic transit scintigraphy, a method for quantitatively evaluating the movement of the fecal stream in vivo, was employed to evaluate colonic transit in the cat. Scintigraphy was performed in duplicate in five cats and repeated four times in one cat. After instillation of an 111In marker into the cecum through a surgically implanted silicone cecostomy tube, colonic movement of the instillate was quantitated for 24 h using gamma scintigraphy. Antegrade and retrograde motion of radionuclide was observed. The cecum and ascending colon emptied rapidly, with a half-emptying time of 1.68 +/- 0.56 h (mean +/- SE). After 24 h, 25.1 +/- 5.2% of the activity remained in the transverse colon. The progression of the geometric center was initially rapid, followed later by a delayed phase. Geometric center reproducibility was found to be high when analyzed using simple linear regression (slope = 0.92; r = 0.73; P less than 0.01). Atropine (0.1 mg/kg im) was found to delay cecum and ascending colon emptying and delay progression of the geometric center. These results demonstrate both 1) the ability of colonic transit scintigraphy to detect changes in transit induced by pharmacological manipulation and 2) the fact that muscarinic blockade inhibits antegrade transit of the fecal stream. We conclude that feline colonic transit may be studied in a quantitative and reproducible manner with colonic transit scintigraphy.

Animals↗
PubMed1988

Endoscopic laser therapy for carcinoma involving the esophagus: the value of pretreatment computed tomography.

Computed tomographic (CT) scans of the esophagus were performed on 15 patients with carcinoma of the esophagus or gastroesophageal junction prior to endoscopic laser therapy (ELT). The scans were evaluated for proximity to adjacent structures, symmetry, and luminal deviation, to help the endoscopist plan the route for therapy. A total of 50 procedures were performed without any serious complications. Pretreatment CT scans are a useful adjunct to ELT for carcinomas of the esophagus.

Adult↗
PubMed1987

Prolonged survival and effective palliation in patients with squamous cell carcinoma of the esophagus following endoscopic laser therapy.

Endoscopic laser therapy provides effective symptomatic palliation for patients with squamous cell carcinoma of the esophagus. To investigate whether this treatment also prolongs survival, a retrospective case-control study was performed. Ten patients with squamous cell carcinoma of the esophagus, diagnosed between 1983 and 1985, were treated with the neodymium: yttrium aluminum garnet laser (Cooper Lasersonics, Model 8000, Santa Clara, CA). Twenty patients with the same diagnosis observed between 1979 and 1984 served as age-matched controls. There was no significant difference in sex, race, location of the cancer, prior treatment, or dysphagia scores for the two groups. Laser therapy produced a significant improvement in the mean dysphagia score. Life table analysis demonstrated a median survival of 17.5 months for the patients treated with endoscopic laser therapy compared with 5.7 months for the control subjects (P less than 0.05). One-year survival after laser treatment was 75%, compared with 20% in the control group (P less than 0.05). These results suggest that endoscopic laser therapy is effective for prolonging survival and improving the quality of life in patients with squamous cell carcinoma of the esophagus.

Actuarial Analysis↗
PubMed1987

The effect of oral cisapride on colonic transit.

A prospective double-blind cross-over trial of oral cisapride 10 mg and placebo was performed to determine the effects of cisapride on the transit of colonic contents in normal humans. Six male volunteers were studied twice using colonic transit scintigraphy. After passing a tube to the caecum, 50 mu Ci of 111Indium diethylene triamine pentaacetic acid were instilled into the bowel lumen. The movement of radiolabelled material was followed using a gamma camera interfaced to a digital computer. Cisapride decreased the half-emptying of the caecum and ascending colon from 1.68 +/- 0.4 hours to 0.72 +/- 0.15 hours (P less than 0.05). The total colon half-emptying time was reduced from 38.5 +/- 7.2 hours to 11.1 +/- 2.9 hours on cisapride (P less than 0.05). Cisapride accelerated transit through the transverse colon, but not the descending colon. The progression of the geometric centre was faster during cisapride administration than with placebo (P less than 0.05). The number of bowel movements 48-hours-1 increased after cisapride from 2.5 +/- 0.8 to 5.0 +/- 0.4 (P less than 0.05). This study demonstrates that cisapride has a marked prokinetic effect on colonic transit in normal subjects. Cisapride may be a useful agent in the treatment of constipation.

Adult↗
PubMed1986

Mixed hyperplastic and adenomatous polyp arising from ectopic gastric mucosa of the duodenum.

We report an unusual case of a polyp arising from ectopic gastric mucosa in the duodenum. The polyp demonstrated both hyperplastic and adenomatous proliferation. Adenomatous proliferation in a duodenal polyp arising from ectopic gastric mucosa is, to our knowledge, unique. The areas of adenomatous change were morphologically indistinguishable from those of adenomatous polyps arising in the stomach; hence, the adenomatous change observed in this polyp was regarded as a neoplastic process.

Aged↗
PubMed1986

Colonic transit scintigraphy. A physiologic approach to the quantitative measurement of colonic transit in humans.

Colonic transit scintigraphy was developed to quantitatively evaluate colonic transit. Using this technique the progression of a radiolabeled marker from cecal instillation to defecation was studied in 7 normal male volunteers. An 8-ml bolus containing 50 mu Ci of indium 111-diethylene triamine pentaacetic acid was instilled into the cecum via a 2-mm tube, which was passed orally, and serial scintigrams were obtained over 48 h. By 48 h, 70.7% +/- 9.1% (mean +/- SEM) of the instilled activity had been defecated. The cecum and ascending colon emptied rapidly, with a half-emptying time of 87.6 +/- 27.0 min. Geometric center analysis showed an initial logarithmic progression of activity in the proximal colon and a linear progression distally. This study suggests that the transverse colon, not the cecum and ascending colon, may be the primary site for fecal storage. Colonic transit scintigraphy is a safe, physiologic, and quantitative method for evaluating the colonic transit of fecal material and may provide a useful tool for evaluating normal and abnormal large intestinal physiology.

Adult↗
PubMedDate not supplied

Nonexpandable silicone esophageal stents for treatment of malignant tracheoesophageal fistulas: complications and radiographic appearances.

BACKGROUND: The aim was to evaluate the radiologic appearances and complications that occurred after placement of nonexpandable silicone stents used as palliative therapy for patients with malignant tracheoesophageal fistulas (TEFs). METHODS: Records of 11 patients (6 males, 5 females) who underwent placement of esophageal stents for malignant TEF between 1988 and 1994 were reviewed. Nine patients had esophageal carcinoma and two patients bronchogenic carcinoma. A TEF was documented radiographically in all patients. Silicone stents were placed in all patients under endoscopic guidance. A chest radiograph was obtained for each patient immediately following stent placement to confirm proper positioning and to assess complications. A contrast study was performed within 24 hours after the procedure to evaluate the function of the stent and its efficacy for occluding the fistulous tract. The patients were followed until January 1995 or until their death (range 1.5-24. 0 months). RESULTS: Seven of the patients developed stent-related complications. Within the first 24 hours after stent insertion (which was successful in 100% of cases), 2 of the 11 patients developed minor complications. One patient had pooling of contrast around the proximal portion of the stent leading to aspiration of contrast, and one patient experienced transient, asymptomatic, idiopathic, esophagovenous intravasation. Delayed (>24 hours) complications related to stent placement occurred in five of the patients: one patient each had pooling at the proximal end of the stent with aspiration, worsening esophageal dysphagia causing reflux through the stent, caudad stent migration, superior stent migration, epithelial hyperplasia causing obstruction of the stent, and pressure necrosis. There were no cases of hemorrhage. Two patients were lost to long-term follow-up, and eight patients died of their disease, all unrelated to the stent placement. CONCLUSION: Silicone esophageal stents provide successful short-term palliation for most patients with malignant TEF but are not without associated complications. These complications, however, can usually be detected early using radiographic imaging, permitting remediation.

Aged↗