Search PubMed⌕ Search

Biomedical subjects

N Senninger

Publications and source records attributed to N Senninger.

At least 127 records · Page 7Linked to original sources
PubMed1993

Use of the hydrogen clearance technique for measurements of pancreatic blood flow.

The hydrogen clearance technique (HCT) was employed for measurements of local pancreatic blood flow (PBF) in dogs, opossums, and rats under normal conditions and in opossums during biliary pancreatitis. Local PBF (ml/min/100 g) in dogs was 57.6 +/- 10.4, in opossums 60.6 +/- 9.5, and in rats 144.7 +/- 23.4, under resting conditions. Regional distribution of local PBF in dogs showed no statistical differences. Technical aspects of the HCT were described in detail. Under physiological conditions parenchymal trauma following electrode implantation was negligible in nearly all cases. More than 95% of registered clearance curves were monoexponential and showed excellent reproducibility of PBF values in repeated measurements (percentage deviation < or = 6.7). Five days after initiating biliary pancreatitis by common channel ligation in opossums local PBF was 72.1 +/- 14.7 after implantation of new electrodes. Chronically implanted electrodes, however, recorded only 39.7 +/- 15.8, due to massive fibro-proliferative alterations around the implanted electrode tips. We therefore conclude that the HCT as described is a useful tool for measuring local PBF in acute experimental settings only. Biliary pancreatitis in our model causes no significant alterations of PBF after 5 days.

Animals↗
PubMed1993

Is the hydrogen clearance technique a useful tool for measurements of pancreatic blood flow during acute experimental pancreatitis?

Changes of pancreatic blood flow (PBF) during acute pancreatitis (AP) have been under investigation by means of electromagnetic flowmeters, radioactive microspheres, isotope fractionation, radioactive gas clearance, and venous outflow techniques. All methods, however, have certain drawbacks, which make the application of other techniques desirable. In this study, the hydrogen clearance technique (HCT) was tested for the first time in a well-established foxhound model of AP. PBF, systemic blood pressure, and heart rate were monitored over 90 min after the onset of AP and 60 min after therapeutic infusion of Dextran-40 (10 ml/kg body wt). Our results fully agree with the data found by other techniques in this experimental model. Sixty-five of 73 electrodes implanted into the pancreas of eight foxhounds were found working. From 1,024 registered clearance curves, 876 were identified as monoexponential. In the other cases, and only then, we found either dislocation of the electrode tips (n = 6) or perielectrodal hemorrhage during histological examination (n = 4). We believe that the HCT is a feasible and reliable tool for measuring PBF in experimental settings like AP.

Acute Disease↗
PubMed1992

Hormonal control of opossum sphincter of Oddi motility: role of myoneural continuity to duodenum.

Motilin and caerulein are known to affect motility of the sphincter of Oddi (SO) and the gastrointestinal tract. The role of SO-duodenal myoneural continuity in the action of these peptides was studied. Five opossums had translocation of the duodenal papilla into the jejunum, while preserving the blood supply to the SO and duodenum. Serosal electrodes were placed in the SO, duodenum, and jejunum. Five control animals had electrode placement alone. Myoelectric recording was obtained during fasting and after administration of motilin (400 ng/kg) or caerulein (500 ng/kg/hr). Motilin induced premature phase III-like activity in the SO and intestine in controls. After the translocation of the papilla, the spike frequencies during phase II and phase III were significantly lower than in controls, whereas those during phase I and phase IV were not different. Motilin caused premature intestinal phase III and increased SO spike activity. However, the increase in SO spike activity was insufficient to form phase III. Caerulein produced a sustained increase in spike activity in both regions in both groups, but the increase was less in the translocation group than in controls. These data suggest that duodenal activity stimulated by motilin and caerulein participates in the activation of SO motility via intrinsic myoneural pathways.

Animals↗
PubMed1992

Bile-induced pancreatitis.

The main bile-induced pancreatitis models are described with special attention to the duct injection models in dogs and the obstruction/reflux model in opossums. Practical problems of setup, study controls and monitoring are addressed. As for the opossum model, due to its clinical relevance the high variability of problems in the pathogenesis of pancreatitis that may be tackled by this model makes it a very useful, simple and not too expensive tool in the hands of a pancreatitis researcher.

Acute Disease↗
PubMed1992

Advantages and disadvantages of using the hydrogen clearance technique to measure pancreatic blood flow.

This study was undertaken to identify the advantages and disadvantages of using the hydrogen clearance technique (HCT) to measure pancreatic blood flow (PBF) in the opossum over short and long periods. An open study was performed on 8 opossums. A total of 72 platinum electrodes were implanted into the pancreas. On the fifth day 41 additional electrodes were implanted. All implantation sites were examined histologically after five days. Measurements of pancreatic blood flow were taken every other day for five days. Three measurements were taken from each electrode and the mean of the three was used for analysis. In the anaesthetized animal mean PBF (SD) was 63.5 (12.8) ml min-1 100 g-1 immediately after electrode implantation and 34.3 (11.4) ml min-1 100 g-1 on the 5th postoperative day. Of the implanted electrodes, 35% failed during the experimental course, mainly as the result of proliferation of scar tissue around the electrodes. Mild to moderate fibroproliferation had taken place around the platinum tips of the remaining 65%. Primary electrode implantation caused no or negligible trauma to the pancreas. We recommend the HCT only for short-term measurements of PBF. Implantation of electrodes for any length of time leads to inflammatory changes around the platinum tips that cause proliferation of scar tissue and lead to failure of the electrodes, misleadingly low PBF recordings, and fewer monoexponential clearance curves.

Animals↗
PubMed1992

[Liver transplantation after trans-jugular intrahepatic portosystemic stent shunt].

Every third patient with parenchymal liver disease bleeds from esophageal varices. Treatment of this complication is of special interest with regard to liver transplantation which may become necessary later on. The mesocaval H-shunt excluded, surgical shunting results in technical and hemodynamic problems during transplantation. They may be avoided by the new approach of transjugular intrahepatic portosystemic stent shunt (TIPSS). We report our experience with liver transplantation in two patients after TIPSS.

Adult↗
PubMed1991

Arterial steal: an unusual cause for hepatic hypoperfusion after liver transplantation.

Case reports of two patients with an unusual cause for a rapid increase in transaminases following liver transplantation are described. In the postoperative course, angiography revealed an arterial hypoperfusion of the liver due to a steal phenomenon with blood shunting from the hepatic to the splenic artery. In one case, the underlying pathophysiology was a pre-existing filiform stenosis of the celiac trunk with insufficient recruitment of arterial blood from the superior mesenteric artery via the pancreatic arcade. Adequate liver perfusion was restored by simple ligation of the common hepatic artery. In the other case, angiography showed an arteriovenous fistula formation of the splenic vessels and minimal blood flow through the hepatic vessels. This was successfully corrected by angiographic embolization of the splenic artery with metal coils. After therapeutic intervention, both patients rapidly recovered with excellent liver function.

Adult↗
PubMed1990

Sphincter of Oddi cyclic motility. Effect of translocation of the papilla in opossums.

The role of myoneural continuity between the sphincter of Oddi and duodenum in coordinating sphincter cyclic motility and the duodenal migrating myoelectric complex was studied in conscious opossums. Five animals underwent implantation of the duodenal papilla into the jejunum. Myoelectric recording was obtained from the sphincter, duodenum, and jejunum in these animals and from 5 other animals as controls. The mean spike frequency of the sphincter of controls was 1.6 per min during phase I, 4.2 per min during phase II, 11.0 per min during phase III, and 3.6 per min during phase IV of the duodenal migrating myoelectric complex. After translocation of the papilla, the spike rates during phase II (2.2 per min) and phase III (2.8 per min) were lower than in controls (p less than 0.02), while those during phases I and IV remained unchanged. Feeding disrupted the migrating myoelectric complex and increased sphincter spike activity in both groups; however, the plateau frequency after feeding was lower after the translocation. These data suggest that the duodenum does not control cyclicity of sphincter motility but sphincter-duodenal intrinsic myoneural continuity is important in the increase in sphincter spike activity during phases II and III and after feeding.

Ampulla of Vater↗
PubMed1990

Prostanoid release in experimental liver transplantation.

Prostanoids are biologically active mediators of inflammation and tissue injury. To investigate the role of prostanoids in orthotopic liver transplantation we used a porcine model and determined prostaglandin E2, 6-keto-prostaglandin F1 alpha, and thromboxane B2 in arterial, portal, and hepatic venous blood during organ harvesting, the recipient operation, and the early postoperative period. There were no significantly increased serum levels during the donor operation or at the end of cold storage. As early as 1 or 5 min after initiation of reperfusion of the transplanted organ, prostanoids in hepatovenous blood increased dramatically (100-500-fold). Changes in arterial and portal blood (10-50-fold) were less pronounced but still statistically significant. In surviving animals these values returned to normal within 24 hr. The hepatic release of metabolites of the arachidonic acid cascade after liver grafting indicates that the synthesis of prostanoids might contribute to morphological and functional alterations of the transplanted graft. In addition, the increased arterial values of circulating prostanoids may potentially participate in severe cardiovascular, hemostatic, and immunological alterations known to occur after liver transplantation.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Evaluation of preservation damage after porcine liver transplantation by assessment of hepatic microcirculation.

The ischemic damage following liver transplantation (LTX) is predominantly located at the endothelial cell level and is a major cause for a disturbance of microcirculation. The present study was designed to test the hypothesis that changes in the quality of organ preservation are correlated with changes in microcirculation: 16 pigs underwent LTX, preservation by Bretschneider's HTK-solution (Histidin, Tryptophan, alpha-Ketoglutarat) complemented by indomethacin (50 mumol/L). Cold ischemia times were 9 hr (n = 8) and 18 hr (n = 8), respectively. Using the H2-clearance technique, hepatic microcirculation was measured before, 30 min, and 20 hr after LTX. Normal tissue perfusion was 107 +/- 16 ml/100 g/min, at 30 min posttransplantation 91 +/- 13 ml/100 g/min in the short-term and 48 +/- 7 ml/100 g/min in the long-term preservation group. Whereas no animal of the long-term preservation group survived longer than 8 hr, all animals of the short-term preservation group survived, and tissue perfusion could be measured 20 hr postoperatively (101 +/- 19 ml/100 g/min). At 30 min postoperatively, all surviving animals had tissue perfusion rates greater than 70, and all nonsurvivors had values below 60 ml/100 g/min. We conclude therefore that the extent of decrease of microcirculation after LTX may be a useful predictor of organ function and survival.

Alanine Transaminase↗
PubMed1987

Effect of nifedipine on the motility of the sphincter of Oddi and small bowel of the opossum.

The effect of the calcium-channel blocker nifedipine on the electromyographic activity of the small bowel and sphincter of Oddi was studied in conscious opossums. Electromyographic and arterial pressure recordings were started 7-10 days after implantation of seven pairs of electrodes along the small bowel and sphincter of Oddi. Continuous infusion of nifedipine caused a dose-dependent reduction of the frequency of spike bursts in the small bowel and sphincter of Oddi. Nifedipine at high doses abolished the migrating motor complex in the gastrointestinal tract. The frequency of slow waves was unchanged. This drug possibly inhibits the membrane influx of calcium into the smooth muscle cells of the gastrointestinal tract. We conclude that nifedipine causes an intense decrease in the motility of the small bowel and sphincter of Oddi.

Ampulla of Vater↗