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Biomedical subjects

B Pannen

Publications and source records attributed to B Pannen.

6 recordsLinked to original sources
PubMed1996

Different effects of early endotoxaemia on hepatic and small intestinal oxygenation in pigs.

OBJECTIVE: Study on simultaneous O2 supply/uptake relationships in liver and gut during endotoxaemia, to determine whether signs of dysoxia develop uniformly in the splanchnic region. DESIGN: Animal study to assess the early effects of endotoxaemia on oxygenation of both liver and small intestine. INTERVENTIONS: Eight anaesthetized pigs received a continuous portal venous infusion of lipopolysaccharide (0.5 microgram.kg-1.h-1) for 6 h. Systemic, pulmonary and splanchnic haemodynamics as well as systemic and splanchnic O2 supply/uptake relationships were determined. RESULTS: There was a multiphasic haemodynamic response pattern characterized by an early (within the 1st h) and a subsequent more prolonged phase (between the 2nd and 6th h) of decreases and recovery of hepatic arterial, portal venous and superior mesenteric arterial blood flows (electromagnetic flow probes) and splanchnic O2 deliveries. Unrelated to perfusion pressure and O2 delivery, there were early and sustained decreases in ileal mucosal surface partial pressure of oxygen (PO2) (multiwire PO2 electrode) and pH (tonometry). This was not reflected by ileal serosal surface PO2, O2 uptake and arteriomesenteric venous pH and partial pressure of carbon dioxide (PCO2) gradients. There was little evidence of concomitant hepatic dysoxia as evaluated by surface PO2. CONCLUSIONS: The study demonstrates early and sustained regional (mucosa) intestinal hypoxia with little evidence of simultaneous hepatic dysoxia during initial endotoxaemia.

Animals↗
PubMed1991

[Angiographic and histologic findings in high frequency rotational ablation in coronary arteries in vitro].

High-frequency rotational angioplasty is a recently developed method for coronary angioplasty in the catheter laboratory. An elliptical burr tip (phi 1.25-2.0 mm) with embedded diamant chips (phi 40-50 microns) is rotated by a helical drive shaft at 150,000-180,000 rpm. The burr is advanced over a 0.009-inch coaxial guide wire. To show the effects of this approach in diseased and healthy vessels, which may be present before and behind a stenosis, 17 atherosclerotic coronary arteries of nine human hearts, and 18 normal coronary arteries of nine pig hearts were treated by this method in vitro. Standardized coronary angiography was performed before and after Rotablator treatment, followed by histological examination. From these data the burr-to-vessel-diameter ratio was calculated for each vessel segment and compared with the angiographical and histological outcome. Partial or complete removal of the circumference of the innermost vessel wall layers was observed regularly. The average removal of tissue in human coronary arteries was limited to the intimal layer and in the pig coronary arteries to the internal elastic membrane. In the pig coronary arteries no intimal tears or dissections occurred, in human coronary arteries tears could be seen frequently (13 of 17 vessels (76%)). Media tears were observed in 3 of 17 vessels; one (2%) media dissection could be demonstrated; no perforation occurred. Thus, the in vitro studies suggest that coronary rotational angioplasty has only a slight effect on the vessel segment next to a stenosis, regardless of the burr-to-vessel-diameter ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1989

[The significance of laminin for the stability of endothelial-substrate adhesion in rheologic conditions].

The glycoprotein laminin is a component of the extracellular matrix and seems to be of considerable importance for cellular adhesion. In static cell cultures laminin revealed a profound influence on migration and proliferation of cultured endothelial cells. Coating of coverslips with laminin was found to have a profound and long-lasting effect on the adhesiveness of endothelial cells exposed to experimental fluid shear stress. By changing the seeding density of the cells per cm2 we could stimulate endogenous laminin production to a level that increased resistance of the monolayer against rheological shear stress by 200%.

Cell Adhesion↗
PubMed1988

Intercalated cells as a probable source for the development of renal oncocytoma.

Renal oncocytoma is a distinct type of epithelial tumor said to arise from the collecting duct system. Here we show that in nine of ten oncocytomas the tumor cells expressed an analog of the erythrocyte anion exchanger band 3. In the normal kidney band 3 is confined to the basolateral surface of the majority of intercalated cells which comprise up to 50% of the cortical collecting duct epithelium. Carbonic anhydrase c is another protein abundant in intercalated cells, and this was also expressed in six of the ten oncocytomas investigated. Immunoreactivity specific for band 3 and carbonic anhydrase c was not detected in any of the 20 renal cell carcinomas examined. At favourable section planes direct transitions between normal collecting ducts and oncocytic tubules were observed. These findings suggest that oncocytomas may develop from intercalated cells of the collecting duct epithelium.

Adenoma↗