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S Bar-Meir

Publications and source records attributed to S Bar-Meir.

At least 55 records · Page 3Linked to original sources
PubMed1996

Preoperative assessment of blood vessel involvement in patients with pancreatic cancer.

The major prerequisite for resection of a pancreatic tumor is non-involvement of large blood vessels. Preoperative assessment of blood vessel infiltration may prevent unnecessary surgery. The aim of our study was to investigate the accuracy of endoscopic ultrasonography (EUS) in diagnosis of pancreatic cancer and in preoperative staging. Thirteen patients (7 females, 6 males; mean age 64 years) with a pancreatic tumor, but no evidence of distant metastases, underwent EUS and computerized tomography (CT) in order to assess blood vessel involvement by the tumor. The results were compared with intraoperative findings in 12 patients and with postmortem findings in 1 patient. A tumor was demonstrated by EUS in 12 patients and was confirmed at surgery in all 12 patients. In one patient no tumor was demonstrated by EUS, although a tumor was visible by CT; no tumor was found at surgery. In two patients CT failed to demonstrate a pancreatic tumor that was demonstrated by EUS; at surgery a tumor was detected in both patients. EUS detected blood vessel involvement in seven patients, which was confirmed at surgery in six of them. In the other six patients surgery confirmed the EUS finding of no blood vessel involvement. CT detected blood vessel involvement in two patients only. The overall accuracy of EUS and CT for detecting the tumor was 100% and 77% respectively, and for blood vessel involvement 92% and 61% respectively. In conclusion, EUS is an accurate procedure for preoperative assessment of blood vessel involvement in patients with pancreatic cancer. This procedure may enable the selection of those patients who may benefit from surgery, and should be part of the evaluation of patients with pancreatic cancer who are candidates for curative surgery.

Adenocarcinoma↗
PubMed1994

Famotidine has no effect on cardiac performance and liver blood flow in the rat.

Conflicting results have been reported on the effect of famotidine on cardiac performance and visceral hemodynamics, studied by non-invasive techniques. It is for that reason that we used the radioactive microsphere technique to study the effect of famotidine on cardiac performance in the rat. Hepatic blood flow (HBF) and portal blood flow (PBF) were measured during the same experiment. Rats were either given famotidine (2.0 mg/kg per day) or drinking water for 7 days through an orogastric tube. Administration of famotidine had no effect on cardiac output (CO), HBF, PBF, or liver blood flow (LBF), which is the sum of HBF and PBF. In both groups, LBF consisted of a similar fraction of CO, 14.5 +/- 3.9% and 15.7 +/- 4.38%, in the control and the famotidine groups, respectively. Pulse rate, systolic pressure and left ventricular contractility were not affected by famotidine. It is concluded that in the rat, administration of famotidine for 7 days has no effect on systemic, hepatic or portal hemodynamics.

Animals↗
PubMed1994

Vanadate has no effect on insulin-extraction by the rat liver.

The mechanism(s) responsible for the insulin-like effects of vanadate are still unclear, although several possible explanations have been raised. However, the possibility that vanadate induces inhibition of insulin degradation in the liver was not examined yet. Therefore, in the present study we examined the effect of vanadate on the extraction of insulin by the perfused rat liver using an open, non-recycling system. Baseline insulin extraction (44 +/- 2% and 37 +/- 3%) was not affected by the administration of 1 and 5 microM vanadate (decreased to 42 +/- 2% and 36 +/- 1, respectively, p = NS). Vanadate had no adverse effects on liver viability, and the bile flow remained stable during and after vanadate administration (0.87 +/- 0.08 microliter/min/g liver prior to Vs. 0.084 +/- 0.11 microliter/min/g liver following vanadate administration). This study shows that vanadate does not inhibit insulin extraction by the perfused liver, and that does of vanadate that effectively inhibit hepatic glucose production possess no adverse effects on liver viability.

Animals↗
PubMed1993

Recovery of pressor response to norepinephrine following relief of the obstructed common bile duct in the rat.

Jaundice caused by common bile duct (CBD) obstruction is associated with a blunted pressor response to norepinephrine (NE). We studied the rate and extent of recovery of the pressor response in the rat following relief of the obstruction. Three groups of male Wistar rats underwent CBD ligation. In the first and second group blood pressure measurements were obtained at 72 and 144 h after CBD ligation, respectively. In the third group pressure measurements were recorded 72 h after the relief of a 72-h obstruction. A fourth group served as control, and measurements were obtained 72 h after a sham operation. In all four groups measurements included basal blood pressure and pressure change following escalating doses of NE, ranging from 0.5 to 10 micrograms/kg. Basal blood pressure was similar in all four groups. In the control group the change of blood pressure was 23.4% +/- 6.7% in response to the lowest dose of NE, and 83.5% +/- 24.9% in response to the highest dose. A blunted pressor response to NE was recorded in all three groups with CBD obstruction. The duration of CBD ligation (72 or 144 h) did not affect this blunded response. Re-establishment of bile flow for 72 h made only a slight improvement in the response to NE. Obstruction of the CBD was associated with hyperbilirubinemia which disappeared following the re-anastomosis of the CBD to the duodenum. This most significant decrease in serum bilirubin was not associated with a similar improvement in pressor response to NE. We conclude that in the rat CBD obstruction is associated with a blunted pressor response to NE, that relief of CBD obstruction for 72 h is insufficient to abolish this response, and that there is no full correlation between serum bilirubin and pressor response.

Animals↗
PubMed1992

Recovery of hepatic clearance and extraction following a release of common bile duct obstruction in the rat.

The rate of recovery for hepatic clearance and extraction following release of common-duct obstruction was investigated in the rat. Male Wistar rats underwent ligation of a cannulated common bile duct. Two weeks later, the cannula was opened and implanted into the duodenum, thus re-establishing enterohepatic circulation. Hepatic extraction and indocyanine green clearance were determined in three groups of six rats each, which differed by the time elapsed from the re-establishment of communication between the common bile duct and duodenum, i.e., 1, 48 and 168 h, respectively. A fourth group, in which a sham operation was performed, served as a control. Clearance was reduced from 16.9 +/- 2.5 ml/min per kg in the control group to 2.9 +/- 0.8, 5.4 +/- 2.4, and 8.5 +/- 3.3 ml/min per kg 1, 48, and 168 h, respectively, after release of common-bile-duct obstruction. Extraction rate was reduced from 37.3 +/- 5.9% to 17.5 +/- 2.7% in the 1st hour and recovered completely at 1 week. Thus, in the rat, release of a 2-week common-bile-duct obstruction is associated with complete recovery of the extraction capacity of the liver within a week, but only incomplete recovery of clearance. This decrease in clearance seems to be due to a decrease in effective hepatic blood flow, mostly probably due to the development of porto-systemic shunts.

Animals↗
PubMed1991

Vanadate inhibits glucose output from isolated perfused rat liver.

Previous studies have demonstrated that vanadate ions mimic many of the actions of insulin in in vitro systems. Also, vanadate administered to diabetic hyperglycemic rats lowers their blood glucose levels to normal values. In this study we demonstrate that vanadate inhibits glucose output in the isolated perfused rat liver. Glucose production was suppressed maximally (about 50% to 60%), on addition of extremely low vanadate ion concentrations (0.5 to 1 mumol/L). This concentration is about two log units lower than the vanadate ion concentrations that are required to activate hexose uptake and glucose metabolism in vitro and is within the range of endogenous intracellular vanadium concentration. Insulin had little or no effect in inhibiting hepatic glucose output in this experimental system. The effect of vanadate ions is rapid in onset and is not accompanied by any signs of liver toxicity as assessed by various criteria. In conclusion, the study indicates that (a) vanadate ions inhibits hepatic glucose output, maximally and at extremely low, nontoxic concentrations (ID50 = 0.7 +/- 0.1 mumol/L). (b) The modulation action of the ion is fast and probably occurs at point(s) distal to the insulin receptor itself. (c) The liver participates in the process of maintaining euglycemia in diabetic rats receiving optimal doses of vanadate orally.

Animals↗
PubMed1990

Cimetidine and omeprazole have different effects on hepatic extraction of lidocaine in rats.

The effect of two antisecretory drugs, omeprazole and cimetidine, on the hepatic extraction of indocyanine green and lidocaine was studied in the isolated perfused rat liver. Both indocyanine green and lidocaine are removed by the liver with high extraction efficiency in a flow-dependent manner. The elimination of lidocaine, but not indocyanine green, involves metabolism by the mixed-function oxidase in the liver. A selective effect on the hepatic extraction of lidocaine, but not indocyanine green, may therefore indicate an inhibition of hepatic mixed-function oxidase. To test this hypothesis, a nonrecycling system at a fixed perfusion flow rate was used to measure the extraction of lidocaine. Under control conditions, the extraction rate of lidocaine was 83% +/- 8%. In the presence of omeprazole at concentrations of 0.9, 2.0, and 4.5 micrograms/mL, the extraction rates were 81% +/- 9%, 82% +/- 7%, and 75% +/- 7%, respectively. These changes were not significantly different than control rates. In contrast, the increasing concentrations of cimetidine caused significant decreases in the hepatic extraction of lidocaine to values of 78% +/- 8%, 63% +/- 14%, and 48% +/- 14% at concentrations of 0.25, 0.50 and 1.25 micrograms/mL, respectively. The hepatic extraction of indocyanine green, 39% +/- 6%, was not affected by the administration of either omeprazole or cimetidine. Thus, in the rat, omeprazole seems to be a less potent inhibitor of cytochrome P-450 than cimetidine.

Animals↗
PubMed1990

The effect of chronic captopril administration on hepatic blood flow of the rat.

The effect of chronic captopril administration on indocyanine green (ICG) clearance and hepatic extraction has been studied in the rat using the intact liver for ICG clearance and the isolated perfused liver for ICG extraction. The captopril was added to the drinking water to give a calculated daily intake from 0-45 mg kg-1. Hepatic clearance of ICG was dose related from 16.5 +/- 2.4 (control) to 7.2 +/- 1.6 mL min-1 kg-1, respectively. The hepatic extraction of ICG was not significantly different (37 +/- 6%) from the control value in groups on 4 and 45 mg kg-1 daily. Since ICG clearance and extraction are dependent on hepatic blood, a change in ICG clearance without a change in the extraction reflects a similar change in the hepatic blood flow. This remained unchanged at daily captopril intakes of 1 and 4 mg kg-1 and decreased when the daily intake was 10 mg kg-1 or higher. If these results in the rat are applicable to man, the chronic administration of therapeutic doses of captopril (0.5-2 mg kg-1) will not affect the hepatic blood flow.

Animals↗