Fibrin-glue-coated collagen fleece in lung surgery--experimental comparison with infrared coagulation and clinical experience.

Diffuse parenchymal bleeding and major air leaks still present a challenge to the thoracic surgeon. This study was therefore designed to evaluate efficacy and handling of fibrin-glue-coated collagen fleece, to address these problems. In an experimental part defects were produced in lungs of troll pigs to compare the use of the fleece with infrared coagulation. Immediate airtightness and postoperative adhesions were evaluated. Scores were designed to evaluate quality and extension of the adhesions. In a clinical study parenchymal resection sites were sealed with fibrin-glue-coated collagen fleece in 52 patients. No patient suffered from postoperative bleeding. In three cases air leaks were still present on the third postoperative day, representing a 5.8% failure rate. 92.3% of the patients showed neither postoperative hemorrhage nor prolonged air leaks. A fixed combination of collagen fleece and fibrin glue consequently can be considered as a valuable tool in thoracic surgery.

Haemostyptic preparations on the basis of collagen alone and as fixed combination with fibrin glue.

Preparations containing collagen play a prominent role among local haemostyptic agents in surgery. Sheets of collagen are used as degradable haemostyptic tampons. Various investigations have shown better haemostasis with collagen compared to other degradable materials, although the haemostyptic effect of these collagen preparations is limited. Concerning the mechanism of haemostasis, not all the reactions stimulated, e.g. by the collagen of an injured vessel wall, may be activated by a haemostyptic tampon from collagen. This depends very much on the kind of preparation. The combined application of a sheet of collagen with fibrin glue improved local haemostasis to a great extent. Large areas of capillary bleeding can be treated successfully with this method. Despite the very good results, this method has not been applied on a broad scale. This is due to the necessary skill and experience and the relatively cumbersome preparation required at the operation site. These drawbacks have been overcome with the latest development in this field--a sheet of collagen covered with a fixed layer of the solid components of a fibrin glue (fibrinogen, thrombin and aprotinin). The performance of this new local haemostyptic agent is described with special emphasis on the results of clinical trials. Haemostasis of large areas of capillary bleeding was very efficient and safe with the new material. Moreover, bile leakage and liquor, pancreatic and aerial fistulae could be sealed without problems.

The conjunctival approach to the orbital floor and maxilla--advantages and disadvantages.

The conjunctival approach to the infraorbital rim and the orbit is discussed. A series of patients is presented with a small number of complications. The technique is described and the important factors in preventing problems are emphasized.

The effect of polycations on the inhibitory action of antithrombin III on thrombin in the absence and presence of polyanions.

Polycations of biological and synthetic origin inhibit the action of AT III on thrombin activity. The effect is more pronounced with increasing molecular weight of branched polycations. Quantitatively protamine causes the same effect as quaternized polycations on the basis of charge equivalence. The accelerating effect of heparin or potassium polyvinylsulfate for the inhibitory action of AT III is abolished by charge equivalent amounts of polycation. The observations indicate a dual action of polycations in the heparin/AT III/thrombin interaction.

The role of surface charge on the accelerating action of heparin on the antithrombin III-inhibited activity of alpha-thrombin.

We have compared surface charge and the surface charge density on the polyanions heparin and potassium polyvinyl sulfate (KPVS), as well as on hydrolyzed heparin and KPVS, with their accelerating effect on the inhibitory action of antithrombin III on thrombin. Polyelectrolyte titration of thrombin with KPVS or heparin at pH 7.4 clearly indicates an electrostatic interaction. In contrast, at the same pH no electrostatic interaction is observed between polyanions and antithrombin III. KPVS accelerates the inhibitory action of antithrombin III to the same extent as heparin on the basis of charge equivalence. Heparin and KPVS with a mean distance between two charged centers of less than 0.75 and 0.95 nm, respectively, accelerate strongly whereas hydrolysates with lower charge densities are far less active. The following observations are indicated. Intramolecular neutralization of oppositely charged residues occurs within thrombin, antithrombin III, and partially hydrolyzed heparin. Heparin acts on the antithrombin III-thrombin reaction through cooperative electrostatic binding to thrombin and nonelectrostatic interaction with antithrombin III. This indicates a quasi-catalytic action of the polyelectrolyte. Hydrolysis of only a few N-sulfate residues within the heparin molecule decreases the linear surface charge density to such an extent that the accelerating action is drastically reduced. The loss of accelerating capacity agrees with the sudden loss of counterion condensation due to the decrease of the linear surface charge density beyond limits postulated by Manning in a theory of polyelectrolytes.

Diacylglycerol acyltransferase from rat liver microsomes. Separation and acyl-donor specificity.

1. Diacylglycerol acyltransferase was resolved from rat liver microsomes and separated from glycerolphosphate acyltransferase and 1-acylglycerolphosphate acyltransferase. The separation was achieved by sucrose-density-gradient centrifugation of the enzyme preparation which was obtained by molecular-sieve chromatography of microsomes solubilized with a nonionic detergent, Triton X-100. 2. Although diacylglycerol acyltransferase and 1-acylglycerolphosphorylcholine acyltransferase were not separated from each other, the two acyltransferases were distinguishable with respect to heat stability and sensitivity to sulfhydryl-binding reagents. 3. Studies with the diacylglycerol acyltransferase preparation obtained have shown that this enzyme possesses a broad acyl-donor specificity, utilizing saturated, monoenoic, dienoic and tetraenoic fatty acyl-CoA thioesters efficiently. 4. A simplified assay method for diacylglycerol acyltransferase is described.

Decreased dissociation of the 3-methylcrotonyl-CoA carboxylase complex from Achromobacter in the presence of 3-methylcrotonyl-CoA. A possible regulatory mechanism for the intracellular degradation of the enzyme.

By inactivation of different concentrations of 3-methylcrotonyl-CoA carboxylase from Achromobacter IVS with a fixed concentration of iodoacetamide, it was demonstrated that the degree of dissociation of the complex is considerably lower in the presence of 3-methylcrotonyl-CoA. ATP did not produce this effect. This property could serve to regulate the intracellular degradation of the enzyme, if the dissociated subunits were attacked preferentially.

Investigations of the structure of 3-methylcrotonyl-CoA carboxylase from Achromobacter.

It was shown by gel electrophoresis in sodium dodecylsulphate solution that 3-methylcrotonyl-CoA carboxylase from Achromobacter IVS is composed of two different subunits with molecular weights of about 78000 and 96000, respectively. The biotin is bound to the heavier subunit. It was previously found that 3-methylcrotonyl-CoA carboxylase contains four biotin molecules per complex. A complex composed of four of each subunit would thus have a molecular weight of about 700000. This is compatible with the molecular weight of 760000 determined earlier by analytical ultracentrifugation. Both subunits were isolated preparatively. As the subunits, unlike the complex, are very sensitive to oxygen, special precautions had to be taken during isolation. The biotin-containing subunit was isolated by chromatography on DEAE-cellulose in 5 M urea. It no longer catalyzed the overall reaction, yet could still carboxylate free biotin. The biotin-free subunit was separated after dissociation of the enzyme by three-days' dialysis at pH 9.8 under nitrogen. On chromatography over a Sepharose-bound avidin column, the biotin-subunit was fixed and the biotin-free subunit was eluted unretarded. The latter subunit showed no enzymic activity. After the addition of the biotin-containing subunit, overall activity was regenerated. The speed of reassociation is very much enhanced by 3-methylcrotonyl-CoA. It was shown by reassociation experiments under different conditions that probably an initial complex, AxBy is formed, possessing a binding site for 3-methylcrotonyl-CoA. Upon the binding of this substrate the conformation may be changed to a form favourable for reconstitution. Finally, the structures of biotin enzymes from different sources are compared. In the course of evolution there is a tendency toward integration of the different constituent proteins into only one polypeptide chain.