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Biomedical subjects

G Schlag

Publications and source records attributed to G Schlag.

At least 145 records · Page 8Linked to original sources
PubMed1988

Development of a simple radioimmunoassay for human C3a.

A radioimmunoassay was devised for the human complement cleavage product, C3a, using charcoal separation and selective precipitation of interfering substances. When compared with the commercially available immunoassay now marketed, the assay reported here was somewhat simpler to perform; furthermore, it overcame delivery and availability problems in Europe. The assay showed a mean recovery of 87% of known amounts of C3a or C3adesarginine and had a sensitivity of 32 ng C3a per milliliter of plasma; coefficients of variance were comparable to other radioimmunoassays in common use. Using this assay in a first clinical application, we were able to document a small but statistically significant rise in [C3a] during cardiopulmonary bypass.

Anaphylatoxins↗
PubMed1988

Control of perfusion pressure and flow in isolated heart bioassays.

Bioassays using isolated animal hearts are important tools for the investigation of cardiac behaviour, but to obtain accurate results a proper perfusion circuit has to be designed. In particular, biophysical studies of contractile and vascular behaviour require a perfusion circuit which permits the adjustment of several experimental parameters within wide ranges. It must also be able to maintain the stability of these parameters when the behaviour of the isolated organ undergoes major changes. To meet this requirement, we have developed a perfusion circuit which makes it possible to control either the perfusion pressure or the coronary flow, with a high degree of precision. There is an electronic controller which satisfies the requirements of a variety of safety and experimental requirements and guarantees a well-defined perfusion system. Computer simulation of the interaction between the perfusion circuit and the heart identified the basic elements of this time-variable, nonlinear system.

Animals↗
PubMed1988

Cardiopulmonary responses to continuous administration of endotoxin.

The cardiopulmonary response to continuous administration of lipopolysaccharide (LPS) was studied in chronically instrumented sheep. LPS was administered in doses of 0 (sham), 6, 9, 12, and 24 ng.kg-1.h-1 for 24 h. No significant changes in the measured variables occurred in the sham group and in the 6 ng.kg-1.h-1-LPS group. With 9, 12, and 24 ng.kg-1.h-1-LPS, cardiac index rose and peripheral resistance fell to the same extent in all three groups. Lung lymph flow (QL) increased with increasing concentration of LPS. These elevations in QL occurred in the presence of only minor increases in the pulmonary artery pressure, which rose to the same extent in the 9, 12, and 24 ng.kg-1.h-1 groups. Consequently, the changes in QL were attributable to changes in fluid conductance of the pulmonary microvasculature rather than variations in hydrostatic pressure. The increase in QL correlated with a decrease in prekallikrein levels (r = 0.97), indicating that the changes in fluid conductance might have been kinin mediated.

Animals↗
PubMed1988

Fibrin sealant in orthopedic surgery.

The use of clotting substances from blood for hemostasis dates back to 1909. In 1972, modern fibrin sealing (FS) was developed in Vienna. For application, the two components, i.e., a sealer protein solution (mainly fibrinogen) and a thrombin solution, are mixed to produce the fibrin clot. The sealant may be applied with a needle, as a spray, or by premixing (e.g., with antibiotics, bone chips) for subsequent sealant application in cavities. While the positive effect of FS in normal wound healing has been conclusively demonstrated, its influence on bone healing remains controversial. The positive experimental results mostly refer to the early phase of bone healing in rabbits (cortical drill hole, autologous and heterologous (Kiel) cancellous transplants, osteotomies, osteochondral fractures) and dogs (cortical bone and spongiosa defects). Some authors observed no effects (in dogs, osteotomy) or delayed healing in artificial bone growth chambers with the use of heterologous sealant. FS was also applied in combination with implantation material (tricalcium phosphate and bone gelatin) to facilitate application. Clinical results are especially convincing as to osteochondral fractures, repair of the Achilles tendon, and in hemophiliacs. Fibrin sealant facilitates hemostasis, permits tissue fixation, enhances plasticity of granular implant material, and stimulates fibroblast growth. Although its direct osteogenic effect remains questionable, fibrin sealant is known to be an excellent tool in orthopedic and trauma surgery.

Animals↗
PubMed1988

A new technical of liver biopsy with plugging of the needle track using a double channel biopsy device. An experimental study.

A new liver biopsy technique with plugging of the intrahepatic needle track in one procedure using a double channel biopsy device (Austrian patent No 384,165 invented by K. Zatloukal and H.P. Dinges) is presented in an experimental study. This technique is similar to that described by Menghini, but is combined with a fibrin sealing system (Tissucol, Tisseel). Biopsy and sealing of the biopsy site is performed within less than two seconds. 15 liver biopsies were performed on 6 heparinized dogs after laparotomy. Heparinization was maintained for 6 hours and the efficiency of the sealing in preventing biopsy-related bleeding was checked before the abdominal wound was closed. No bleeding occurred after biopsy with the new needle system and occlusion of the needle track with fibrin sealant. The livers with the sealed needle tracks and all biopsies obtained were examined histologically. It was found that the needle tracks were filled with the fibrin sealant which was almost completely replaced by granulation tissue after 8 days. Biopsies performed with a conventional Menghini needle led to continuous bleeding from the needle track. The results show that this new biopsy device efficiently prevents bleeding from the biopsy site in animals with severely impaired blood coagulation. Therefore, application of this biopsy technique in humans might reduce bleeding complications particularly in patients with severe liver diseases and disturbed blood coagulation.

Animals↗
PubMed1988

Reduction of the cardiopulmonary response to endotoxin by the administration of aprotinin.

The antiprotease aprotinin (Trasylol) (20,000 KIU bolus/kg followed by 10,000 KIU/(kg x h) for 8 h) was administered to sheep which were then given a continuous dose of endotoxin (24 ng/(kg x h) for 24 h). Their cardiopulmonary response was compared to a group of sheep which received endotoxin alone as well as a sham group which received neither endotoxin nor aprotinin. The response to endotoxin was characterized by an increased lung lymph flow and cardiac output. This response was blocked by the administration of aprotinin. In the endotoxin group there was a fall in prekallikrein levels. The action of aprotinin suggests that the cardiopulmonary response to endotoxin may be mediated by the formation of bradykinin.

Animals↗
PubMed1988

The elastase-inhibitor eglin has no effect in an ovine model of endotoxemia.

Small doses of endotoxin have been shown to induce pulmonary microvascular injury in sheep, possibly by the action of granulocytes. Eglin, a potent inhibitor of neutrophil elastase, was tested in an ovine model of endotoxemia. The experiment was performed in 12 unanesthetized chronically instrumented sheep with a lung lymph preparation. Endotoxin (S. abort. equii) was infused at 24 ng/(kg x h) with application of 20 mg/kg eglin 1 h before endotoxin in the treatment group and followed by 5 mg/(kg x h). No significant improvement due to the treatment was seen for either cardiovascular status (pulmonary and systemic vascular resistance) or permeability changes in the lung (lymph flow and lymph/plasma protein ratio), although sufficient eglin concentrations were achieved in plasma and lymph. The lack of an effect of eglin might be because higher concentrations are needed to block elastase-like activity of ovine granulocytes or because of a minor role for neutrophil elastase in this shock model.

Animals↗
PubMed1988

Preliminary data on isolation of an elastase-like proteinase and its inhibitor from ovine neutrophil granulocytes.

Ovine polymorphonuclear leukocytes (PMNs) were purified by counterflow centrifugation of the buffy coat. The resulting cell preparation was gently sonicated and ultracentrifuged for separation of cytosol and cell organelles. The proteolytic activity of the isolated enzyme was determined with the specific substrate MeO-Suc-Ala-Ala-Pro-Val-Nan (methoxysuccinyl-[L-alanyl]2-L-prolyl-L-valine p-nitroanilide). Elastase-like activity was identified in the insoluble (particular) fraction, while an inhibitor of elastase activity was found in the supernatant (cytosolic fraction). Further purification of the elastase-like enzyme was achieved by cation exchange chromatography (SP-Sephadex C-25 and CM-Sephadex C-25) and gel permeation chromatography (Bio-Gel P-30). Purification of the inhibitor from cytosol was accomplished using anion exchange chromatography (DE32 diethylaminoethyl cellulose) and two gel permeation steps (Sephadex G-75 and TSK-G 2000 SW - HPLC column). Degrees of purity in all separation steps were controlled with SDS-polyacrylamide gel electrophoresis. The molecular mass of the elastase-like enzyme is in a range of 25 to 27 kDa. The isoelectric point is between 8.0 and 9.0. Three isoenzymes were found. The optimal activity lies at pH 8.0. The molecular mass of the inhibitor is about 40 kDa.

Animals↗