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Biomedical subjects

G Harbauer

Publications and source records attributed to G Harbauer.

At least 19 recordsLinked to original sources
PubMed1995

Comparative effects of secretin (SEC) and cholecystokinin-octapeptide (CCK-8) on pancreatic microcirculation.

Using epifluorescent microscopy, we investigated the dynamic changes in pancreatic microcirculation in vivo after bolus administration of secretin (SEC) (0.1-10.0 micrograms/100 g body wt) and cholecystokinin-octapeptide (CCK-8) (0.005-1.2 micrograms/100 g body wt) in pentobarbital-anesthetized rats. Pancreatic capillary red cell velocity as a monitor for pancreatic capillary blood flow was measured in 1-min intervals from 2 min prior to 8 min following bolus infusion of SEC or CCK-8. Physiological concentrations of SEC did not increase pancreatic capillary blood flow. However, pharmacological SEC concentrations induced a dose-dependent increase in pancreatic capillary blood flow (to 162 +/- 19% of baseline; P < 0.05), due to an increase in blood flow velocity (to 153 +/- 18% of baseline; P < 0.05). In contrast, bolus administration of physiological CCK-8 concentrations, which have been proven to stimulate enzyme secretion, induced a transient and dose-dependent increase in pancreatic capillary blood flow (to 235 +/- 24% of baseline; P < 0.05), due to an increase in blood flow velocity (to 184 +/- 13% of baseline; P < 0.05) and capillary diameters (+0.63 +/- 0.15 micron; P < 0.05).

Analysis of Variance↗
PubMed1995

[Bacterial clearance of the terminal ileum in relation to the ileocolic connection].

The ecology of the (neo-)terminal ileum was investigated in three groups of mongrel dogs (group 1 to 3; 6 animals per each group) depending on the ileocolic connection and the resection of the terminal ileum. The efficacy of a stabilized nipple-valve-anastomosis (SNVA) was evaluated comparing the physiological ileocecal valve and the conventional end-end-anastomosis. The relations of the aerobic and anaerobic bacterial counts of all 18 dogs (group 0) preoperatively served as reference-values. Under this physiological condition the median counts were found to be lower in the ileum than in the colon, two logs for the aerobic bacteria and three logs for the anaerobic bacteria, confirming statistical significance (p < or = 0.05). The resection of the terminal ileum conserving the ileocecal valve (group 1) had no influence on the bacterial flora of the neoterminal ileum, whereas the limited resection of the ileocecal valve with ileocolic end-end-anastomosis (group 2) induced a bacterial colonisation of the terminal ileum. In contrast, following wide ileocoecal resection and replacement of the ileocecal valve by the SNVA (group 3) the bacterial counts were lower in the terminal ileum than in the colon: five logs for aerobic and seven logs for anaerobic bacteria. This difference was statistically significant within this group between ileum and colon and between ileum preoperatively and postoperatively (p < or = 0.05). In conclusion, the bacterial clearance of the (neo-)terminal ileum depends more on the retrograde barrier-function of the ileocecal valve or an appropriate mechanical substitute than on the propulsive motility of the ileum.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1994

[An intestinal neosphincter attained by circumscribed muscle proliferation. Technical development and functional evaluation in the dog].

In an experimental study an intestinal neosphincter (INS) was constructed by modifying the principle of the ileocolic nipple-valve anastomosis by means of ultrasonic tissue fragmentation of the contacting serosa of the ileum and the corresponding mucosa of the ileum and colon. The healing of the muscle layers was studied histologically. The function of the INS was investigated in six dogs and compared intraindividually with that of the ileocecal valve and conventional end-to-end anastomosis. Morphologically the neospincters healed within 3 months without major fibrosis. The reference values of the aerobic and anaerobic bacterial counts in the terminal ileum were more than 2 logs lower than in the colon with the normal ileocecal valve, and after ileo-colonic end-to-end-anastomosis bacterial colonization of the terminal ileum was found both qualitatively and quantitatively. Subsequent interposition of the INS led to bacterial clearance of the terminal ileum. The median aerobic bacterial counts were lower by six logs and the an aerobic bacterial counts by 3 logs than in the colon. However, differences were not statistically significant owing to the wide variation in the individual values. Nevertheless, the demonstrable clearance of the terminal ileum could be explained by the orthograde passage with absolutely no stagnation and the relative competence of the INS in resisting retrograde pressure competence. In conclusion, ultrasonic fragmentation of the serosa and mucosa of the bowel allows construction of an INS from three muscle layers, which acts as a bacteriological barrier. Before it is introduced into the clinical setting its integration into the intestinal motility should be evaluated by further studies.

Anastomosis, Surgical↗
PubMed1992

[Evaluating the safety with reference to intravenous tolerance of immunoglobulins].

The section 'Plasmatic Blood Constituents' of DGTI (German Society for Transfusion Medicine and Immunohematology) performed four ACA (anticomplementary activity) ring tests with human immunoglobulins for intravenous application (IVIG). The laboratories carrying out the analyses presented relatively consistent ACA results for IVIG commercial preparations that were obtained by means of the ACA method elaborated based on these tests. The tolerance trials evaluating the IVIGs solely by means of in vitro tests are not sufficient to serve as safety controls since there is no clear correlation existing between the ACA values and their compatibility in the animal model (rat).

Animals↗
PubMed1992

Safety tests of the intravenous tolerance of immunoglobulins. Multicenter study of the section 'Blood Plasma Constituents' of the German Association of Transfusion Medicine and Immunohematology (DGTI).

The Working Group 'Blood Plasma Constituents' of the DGTI has carried out four multicenter trials with human immunoglobulins for intravenous application (IVIG). The ACA method elaborated here has led to relatively consistent ACA results for commercially available IVIG preparations in the participating laboratories. On their own, the in vitro tolerance tests of the IVIGs are not sufficient for safety testing, since there is no clear correlation between the ACA values and the tolerance in a rat model in which changes of blood pressure, pulse rate, ECG and respiratory resistance after administration of IVIGs are determined. The role of polymer constituents in tolerance reactions is to be regarded as substantiated, whereas the tolerance of the dimer fractions of beta-propiolactone-treated IVIGs does not differ appreciably from that of their monomer constituents. Determination of the IgG subclass composition requires standardization. The collation of the antibody specificities to the subclasses must be clarified before making inferences with regard to the clinical significance of the subclass composition of the preparations.

Animals↗
PubMed1991

Comparison of the effects of sodium pentosanpolysulfate and unfractionated heparin on venous thrombosis; an experimental study in rats.

Sodium pentosanpolysulfate (Fibrezym) and unfractionated heparin (Liquemin) had significant antithrombotic efficacy in rats. 1 mg/kg body weight (BW) FibrezymR had its maximal effect 2-4 hours after subcutaneous administration; 200 U/kg BW LiqueminR s.c. were most effective 4-6 hours after application. Both drugs caused frequent embolic break-offs of thrombi during the time periods of maximal antithrombotic efficiency.

Animals↗
PubMed1991

Microcirculatory disturbances and leucocyte adherence in transplanted livers after cold storage in Euro-Collins, UW and HTK solutions.

Integrity of the hepatic microcirculation and maintenance of endothelial cell viability are critical components in preventing primary non-function after liver transplantation. Therefore, hepatic microcirculation and leucocyte-endothelial interaction were studied in rat livers stored for 1 h in Euro-Collins (EC), University of Wisconsin (UW), and histidine-tryptophan-ketoglutarate (HTK) solutions and subsequently transplanted. One hour after transplantation surgery, the livers were exposed under an intravital fluorescence microscope. After injection of the leucocyte marker acridine orange (1 mumol/kg), six pericentral fields were observed for 30 s and experiments were recorded continuously. The percentage of perfused sinusoids was reduced in the livers in the EC group (82.9%) in contrast to the UW (93.2%) and HTK groups (91.0%). Livers in the EC group showed a reduction in the diameters of pericentral sinusoids (7.3 +/- 0.2 microns; mean +/- SEM) compared with the UW group (9.5 +/- 0.2 microns; P less than 0.05) and HTK group (10.2 +/- 0.8 microns; P less than 0.05), indicating substantial cell swelling in livers stored in EC solution. Permanent adherence of leucocytes was most frequently observed in the EC group (33.5 +/- 1%), while this phenomenon was less pronounced in the UW group (14.5 +/- 1.1%; P less than 0.05) and HTK group (16.3 +/- 0.7%; P less than 0.05). Conversely, temporary adherence of leucocytes was reduced in the EC group (19.7 + 1.3%) compared with the UW group (30.5 + 2.1%) and the HTK group (34.4 + 0.8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1991

Hepatic microcirculatory disturbances due to portal vein clamping in the orthotopic rat liver transplantation model.

Most modifications and applications of the orthotopic rat liver transplantation (ORLT) model require clamping of the portal vein, thus leading to ischemia of the gut. The purpose of this study was to evaluate the effect of portal vein clamping during ORLT on hepatic microcirculation and leukocyte--endothelial interaction by intravital fluorescence microscopy. ORLT were performed following 1 hr of cold storage in EuroCollins solution without (standard group) and with insertion of a portojugular shunt (shunt group) to minimize intestinal ischemia. ORLT induced reduction of perfused sinusoids (83%) and velocity of leukocytes (311 +/- 4.5 microns/sec; mean +/- SEM) compared with nontransplanted controls (99% and 417 +/- 4.9 microns/sec). Portojugular shunt during ORLT improved hepatic microvascular perfusion (89% and 355 +/- 3.4 microns/sec; P less than 0.05). Furthermore, percentage of permanent and temporary adherent leukocytes decreased significantly when a portosystemic shunt was applied (from 33.5 +/- 1% to 22.1 +/- 1% and 19.7 +/- 1.2% to 14.0 +/- 0.9%; P less than 0.05). The results of the study reveal that intestinal congestion and reperfusion results in a rise in leukocyte adhesion to the sinusoidal wall and in disturbances of the hepatic microcirculation. It seems likely that increased endotoxin concentrations in the portal vein induce an activation of hepatic macrophages that subsequently cause release of chemoattractant mediators. In conclusion, side effects of intestinal ischemia during experimental liver transplantation surgery on liver function due to release of chemoattractant mediators should be considered when experimental data are transferred to clinical settings.

Animals↗
PubMed1991

Quality control of immunoglobulins for intravenous administration.

Since there is as yet no official European pharmacopoeia or monograph for intravenously administrable immunoglobulins (IVIGs) and the manufacturers of IVIGs use different ACA methods to test their products until today, the study group 'Blood Plasma Constituents' of the DGTI carried out a multicenter study with six IVIGs from five manufacturers. The results of this first multicenter study have not been analysed statistically, because the participants have decided to carry out a second multicenter study using a uniform ACA method.

Animals↗
PubMed1990

Comparison of different prothrombin complex concentrates--in vitro and in vivo studies.

The potency and tests for thrombogenicity were studied prospectively in 7 different (two lots of each brand, A-G) prothrombin complex concentrates (PCC). Human albumine (H) and a factor IX concentrate (I), served as controls. The potency of coagulation factors and inhibitors varied considerably. Two brands (E, F) contained no protein S, additionally one brand contained no protein C. Two preparations exhibited high amidolytic activities, especially towards the thrombin-sensitive chromogenic substrate S-2238, in vitro. These activities could be quenched in part by the addition of hirudin or antithrombin III. The heparin and antithrombin III content of the PCCs was significantly different, and, after addition of antithrombin III an increase of thrombin-antithrombin III complexes in 2 preparations (B, D) was observed in vitro. Additionally, three brands (B, D, F) caused more severe cardio-pulmonary reactions in rabbits, associated with an increase of fibrin split products for brands B and D. We conclude that the use of these preparations in patients, in whom an acquired protein C or S defect, or a hypercoagulable state, can be suspected, cannot be recommended.

Animals↗
PubMed1988

Occlusion of experimental artery aneurysms by intrasaccular injection of fibrin sealant.

Aneurysms were produced by grafting a vein pouch onto the cervical carotid artery of rabbits following the removal of an elliptical piece of the arterial wall. The diameter of the opening was 3-4 mm and the maximum height 8 mm. Through direct puncture of the aneurysm a clot of the fibrin sealant Tissucol was injected into the aneurysm. The sequential morphological changes were studied by light microscopy. One case was examined after 3 weeks by scanning electron microscopy. Complete resorption of the fibrin sealant was observed. The aneurysm cavity was filled with a dense connective tissue covered by a layer of newly formed endothelial cells.

Animals↗
PubMed1988

Anti-IIa and anti-Xa plasma activities after subcutaneous low-dose application of low-molecular-weight heparins to rabbits.

Low-molecular-weight heparin (LMWH) derivatives differ among one another and from unfractioned heparin (UFH) in their half-life as well as in their mode of action. Our aim was to find out, whether the plasma activity levels and their time course after subcutaneous low-dose application of LMWH or UFH in the experimental rabbit are comparable to those in humans. Fairly reasonable standard curves for each LMWH preparation were obtained by using geometrical dilution series of spiked rabbit pool plasma and by applying the methods of Bartl et al. (anti-IIa) and Holmer et al. (anti-Xa). The latter method was slightly modified in order to achieve discernable photometric absorptions for activity levels less than 0.05 U/ml. Rabbits under intravenous general anesthesia received an anterior neck incision. The right external jugular vein was dissected free. A catheter was inserted, advanced into the upper caval vein and kept patent by continuous infusion of 10 ml/h of normal saline. Blood samples of 4 ml were collected in syringes containing 1 ml sodium citrate, before and 1, 2, 4 and 8 h after subcutaneous injection of a LMWH derivative or UFH. The samples were centrifuged and frozen to -30 degrees C. For the estimation of heparin-like anti-IIa and anti-Xa activities the samples were thawed and treated in the same manner as the samples from which the standard curves had been derived.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Experimental investigations on the thrombosis-preventing effect of low-molecular-weight heparins.

6 different preparations of low-molecular-weight heparin (LMWH) derivatives and 1 unfractionated heparin (UFH) were tested for their thromboprophylactic effects in an experimental model which closely simulates clinical conditions. Each preparation was tested in 5 rabbits 2 h and in 5 rabbits 12 h after subcutaneous application of 20-200 U/kg body weight (according to the suggestions of the manufacturers). The animals were anesthetized with intravenous pentobarbital sodium about 90 min or 11.5 h after the application of the heparin preparation. The right external jugular vein was dissected free and a thrombogenesis was provoked. There was no significant protection against occluding thrombosis 2 h after LMWH or UFH injection, when plasma levels of heparin-like activities were found to be high in another experimental series. Surprisingly, there were definite thromboprophylactic effects 12 h (when heparin-like plasma activities had disappeared) after application of 4 (out of 6) LMWH preparations. No protection against thrombosis was seen 12 h after application of UFH.

Animals↗
PubMed1987

Experimental aneurysms in the rabbit: occlusion by intrasaccular injection of fibrin sealant.

Experimental aneurysms of the carotid artery were produced using the microsurgical technique of grafting a venous sack onto the artery in the neck of rabbits after the removal of an elliptical piece of arterial wall. Twenty-five aneurysms were occluded with the fibrin sealant Tissucol. Microscopic examination showed complete resorption of the fibrin clot and the formation of dense granulation tissue within the aneurysm, which was covered with a layer of endothelial cells after 2 weeks. The results are only tentative and require further experimental studies.

Animals↗
PubMed1985

Radioimmunoassay of human serum serotonin.

A radioimmunoassay for extracted, N-acetylated human serum serotonin (5-hydroxytryptamine) is described. Antisera were raised in rabbits against a conjugate of bovine serum albumin with serotonin hemisuccinamide. Polyethylene glycol in combination with anti-rabbit immunoglobulins was used to separate bound and unbound 125I-Bolton Hunter-serotonin conjugate. Ethanol precipitation of serum proteins was used to extract serotonin, which was subsequently acetylated with acetic anhydride to N-acetyl serotonin. The average recovery was 66%. The minimal detectable concentration of N-acetyl serotonin was 0.012 mumol/l serum (25 fmol per tube). The intra-assay precision (CV) was 6.8% (n = 20) at a level of 0.9 +/- 0.06 mumol/l. The inter-assay CV was 10% at a level of 0.49 +/- 0.049 mumol/l, and 25% (n = 10) at a level of 2.16 +/- 0.53. Analytical recovery of serotonin, corrected for losses during extraction and acetylation, was 99 +/- 13%. The only substance cross-reacting with the antibody was endogenous N-acetyl serotonin. This was detectable when the acetylation step was omitted, and it can be removed by extraction before the acetylation. The observed range for the concentration of serotonin in serum was for 59 women 0.45 - 3.46 (mean +/- SD: 1.37 +/- 0.63 mumol/l) and for 59 men 0.19 - 2.8 (mean +/- SD: 1.18 +/- 0.56 mumol/l). All values are corrected for endogenous N-acetyl serotonin: observed range 0 - 0.18 (mean +/- SD: 0.03 +/- 0.03 mumol/l).

Adolescent↗
PubMed1976

[Experimental determination of blood-alcohol metabolism with dogs in haemorrhagic shock (author's transl)].

Ethanol at a dosage of 3 g/kg reduced body weight was injected i.v. into mongrel dogs resulting in a blood alcohol concentration of approximately 2.9 mg/ml. One hour after injection the dogs were anaesthetized with halothane-N20/02 and blood was withdrawn until the blood pressure was reduced to 40 mmHg. This usually required removal of about 30 - 40% of the total blood volume. The resulting haemorrhagic shock was ascertained by monitoring blood pH, pCO2, pO2, lactate, pyruvate and blood electrolytes. A blood specimen for enzymatic alcohol determination (ADH) was obtained every 30 min over a period of 3 hours. Compared with equally dosed controls the dogs in haemorrhagic shock showed a significant (p = 0.005) reduction of the blood alcohol decay rate (beta) which is explained by 1) the diminished blood flow through the liver and 2) the hypoxaemic metabolic situation in shock.

Animals↗