Biomedical subjects
Publications and source records attributed to W Seeger.
An anterolateral transfacial approach for tumors of the retromaxillary space, the nasopharynx, and the middle cranial fossa features a temporary removal of the malar complex and resection of the coronoid process and the pterygoid plates. Two cases demonstrate use of this approach. Results and complications are observed in six patients.
The effects of highly purified Pseudomonas aeruginosa cytotoxin were investigated on cultured pulmonary artery endothelial cells. This toxin dose-dependently (7.5-60 micrograms/ml) and time-dependently (20-75 minutes) stimulated the release of radiolabeled arachidonic acid and metabolites and the synthesis of prostacyclin in the absence of overt cell damage (no enhanced lactate dehydrogenase [LDH] release). Preincubation of the toxin with neutralizing antibodies abolished the effect. The toxin response on endothelial cells required extracellular calcium but not magnesium and was accompanied by a calcium influx. Interference with intracellular calcium function by TMB 8 or with (calcium)-calmodulin function by trifluoperazine and W7 dose-dependently reduced the cytotoxin mediated synthesis of prostacyclin. Calcium channel blockers (nimodipine, diltiazem, verapamil, D 888), however, were ineffective in this system. Following addition of cytotoxin to endothelial cells, an increased passive permeability for small marker molecules (potassium, 45calcium, 3H-sucrose), but for large ones (3H-inulin, 3H-dextran, LDH) was noted, suggesting that cytotoxin creates discrete hydrophilic transmembrane lesions of about 0.5-1.5 nm in diameter. These data are compatible with the notion that Pseudomonas aeruginosa cytotoxin triggers the arachidonic acid pathway in cultured pulmonary artery endothelial cells by calcium influx and suggest that this calcium influx may proceed through toxin created transmembrane lesions.
The authors studied how supralinearity influences individual "deep trap" terms (or levels) of a glow curve that represents the luminous flux emitted by heated LiF rods as a function of energy required for heating. It is assumed that a Gaussian function can be used for glow curve analysis, developing measured glow curves to represent individual "deep trap" terms. Analysis reveals that supralinearity occurs much earlier and more markedly with high temperature peaks than with low ones. This has a bearing on practice.
Studies in erythrocytes indicate that staphylococcal alpha-toxin generates discrete transmembrane channels with an effective diameter of 2-3 nm. In cultured, confluent, pig pulmonary arterial endothelial cells we studied the triggering of the arachidonic acid cascade and its dependence on calcium influx, possibly through toxin-created pores. In endothelial cells alpha-toxin time dependently (5-30 min) and dose dependently (0.1-8 micrograms/ml) stimulated the release of radiolabeled arachidonic acid and prostacyclin (PGI2) production in similar amounts as the calcium ionophore A23187 (10 microM). Preincubation of alpha-toxin with neutralizing antibodies abolished the effect. The toxin response was strictly dose dependent on extracellular calcium but not on magnesium. The toxin effect was accompanied by an up to 10-fold increased passive permeability of pulmonary arterial endothelial cells for 45Ca. Interference with calcium-calmodulin function (trifluoperazine, W7) dose dependently reduced production of PGI2, but blockers of physiological calcium channels (verapamil, nimodipine, nisoldipine, and diltiazem) did not. In contrast to the effect of the ionophore A23187, the toxin effect was accompanied by a release of potassium, but in neither system was there a release of lactate dehydrogenase. In addition, alpha-toxin but not ionophore-exposed endothelial cells showed an increased passive influx of small radiolabeled markers (45Ca and [3H]sucrose) but not of large markers [( 3H]inulin and [3H]dextran). These data are consistent with the concept that alpha-toxin triggers the arachidonic acid cascade in pulmonary arterial endothelial cells by calcium influx and suggest that this calcium influx may proceed through toxin-created transmembrane channels.
In isolated rabbit lungs standardized amounts of edema were induced. Stimulation with the Ca ionophore A23187, leukotriene C4, Pseudomonas aeruginosa cytotoxin and human serum (activated complement) all resulted in protein leakage into the alveolar space with no change in the total phospholipid content. The pressure-volume characteristics of the lungs and the characteristics of the lavage surfactant (Wilhelmy balance) were markedly altered, correlating to the lavage protein content. The surfactant alterations were reproduced by addition of perfusion fluid protein to control surfactant in vitro. All changes were far less expressed or even missing in isolated lungs developing the same amount of edema due to omittance of proteins from the perfusion liquid. Different proteins added to control surfactant in the Wilhelmy balance showed a marked rank order of potency in interfering with surfactant function: immunoglobulins G and M and elastin less than albumin less than fibrinogen less than fibrin monomers. The fibrin monomer effect was reproduced by addition of thrombin to a surfactant fibrinogen mixture and was partly reversed by subsequent incubation with plasmin. In conclusion, high-permeability edema induced by different means results in alterations of lung mechanics and surface activity of lavaged surfactant, presumably due to protein surfactant interaction. Among different proteins, fibrin monomers are especially effective in interfering with surfactant function.
In 58 patients the volume of the kidneys was established by continuous sonographies of the grafts during the first 25 days after operation. In non-rejecting patients it increased on average by 20%, in rejecting and rupturing patients by 35%. The transplants with rupture of the parenchyma revealed the greatest increase to the volume maximum per time unit. The sonography is a suitable screening method for the purpose of rejection diagnostics and can give prognostic statements concerning the threatening rupture of the parenchyma. Rapid increase of the volume, proof of an obstruction of the micturition and constantly high blood pressure levels indicate a threatening rupture of the transplant.
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A combined self-retaining retractor and hand-rest system for neurosurgery is presented. It was developed from the original Leyla system but has the advantage of an integrated hand-rest.
A survey is given of the craniocerebral traumas in children necessitating surgical treatment. The particularities of craniocerebral traumas in children are contrasted to those in adult persons. Diagnostic possibilities and consequences of the injury are discussed.
Two patients with severe, intravascular haemolysis due to drug-dependent antibodies are described. The antibodies were directed against presumptive metabolites of buthiazide (International Non-proprietary Name, butizide) and nomifensine. Their detection was possible only in the presence of ex vivo antigens (i.e. fresh serum of volunteers after ingestion of the drugs) while in vitro antigen preparations yielded inconclusive results. Both antibodies lysed normal red cells in the presence of ex vivo antigens and complement. The buthiazide-related antibody was IgG (subclass IgG1), the nomifensine-related antibody was IgM. We conclude that the use of ex vivo antigens is of great importance in the serological evaluation of cases with suspected drug-dependent immune haemolysis.
Staphylococcal alpha-toxin is known to damage mammalian cell membranes. Studies of erythrocytes indicate that the native toxin generates a discrete transmembrane channel with an effective diameter of 2-3 nm. (Füssle, R., S. Bhakdi, A. Szeigoleit, J. Tranum-Jensen, T. Kranz, and H.J. Wellensiek. 1981. J. Cell Biol. 91:83-94.) In isolated rabbit lungs, perfused with recirculating blood- and plasma-free perfusion fluid, the mediation of a toxin-provoked vascular pressor response by the triggering of the arachidonic acid cascade and its dependence on extracellular calcium were investigated. Dose-dependent pulmonary artery pressor responses were elicited by the injection of 0.5-5 micrograms staphylococcal alpha-toxin into the pulmonary artery. The pressor responses were completely abolished by preincubation of the toxin with neutralizing antibodies or by preformation of alpha-toxin hexamers in vitro. They were accompanied by the release of the arachidonic acid metabolites thromboxane B2 and 6-keto-prostaglandin F1 alpha (stable metabolites of thromboxane A2 and prostaglandin I2, respectively) into the perfusion fluid. They were blocked by inhibitors of thromboxane synthetase, cyclooxygenase, and phospholipase, as well as by substances that interfere with calcium-calmodulin function. alpha-Toxin induced selective release of potassium, but not lactatedehydrogenase into the medium. Calcium depletion of the intravascular space did not suppress the toxin-dependent potassium release but did abrogate the pressor response and the release of the arachidonic acid metabolites. When calcium was reintroduced into the circulation without the application of a second toxin stimulus, marked pressor responses paralleled by the release of arachidonic acid metabolites occurred. The conclusion drawn from these studies is that staphylococcal alpha-toxin provokes pulmonary vascular hypertension which is apparently mediated by thromboxane A2 formation, which surpasses the biological effect of the simultaneously formed prostaglandin I2. The triggering of the arachidonic acid cascade is strictly dependent on extracellular calcium and may be mediated by a nonphysiological calcium bypass through transmembrane toxin channels with subsequent stimulation of phospholipase activity.
A specific method for the detection of organic hydroperoxides in lung lavage fluid (lung surfactant system) and lung tissue homogenate is described. After the inactivation of endogenous GSH peroxidase and GSH reductase and preincubation with catalase, organic hydroperoxides are consumed by addition of GSH and GSH peroxidase. The increase of GSSG, compared to a blank without addition of GSH peroxidase, is measured in a second enzymatic step with GSH reductase. The recoveries of t-butyl hydroperoxide and of peroxidized, free fatty acids added to lavage fluid or to lung homogenate are higher than 85% in each case. The detection limits of this assay for organic hydroperoxides are 0.9 nmol/mg surfactant phospholipid (molar ratio of 0.00066) and 40 nmol/g wet lung weight. The assay detects organic hydroperoxides in the surfactant system of normal rabbit lungs, but not in lung tissue homogenate.
Staphylococcal alpha-toxin is produced by most strains of S. aureus and is considered a major pathogenic factor of these bacteria. The toxin is produced as a water-soluble molecule of MW 34000. Binding to a membrane target is accompanied by the formation of ring-structured hexamers with outer and inner diameters of 10 and 2-3 nm, respectively. The toxin rings carry lipid-binding surfaces that allow for insertion into and firm embedment within the membrane. Small transmembrane channels are thus generated that can induce a variety of pathological cellular changes. Large doses of toxin will generally cause cell lysis and death. However, sub-cytolytic toxin doses can also elicit major pathophysiological reactions. When introduced into the circulation of an isolated and perfused rabbit lung, the toxin causes steep rises in the pulmonary artery pressure, and lung edema results as a consequence of increases in vascular permeability occurring in parallel. These processes are the result of the activation of the arachidonic acid cascade by alpha-toxin in the lung. Studies using cultured endothelial cells as targets subsequently led to a hypothesis that would explain how membrane channel formation by a toxin could be linked to the observed arachidonic acid cascade activation. In essence, we propose that the toxin pores serve as non-physiological calcium channels, and that calcium influx triggers the observed reactions. It is probable that many other pathophysiological processes including inflammatory tissue reactions derive from such secondary effects of toxin action.(ABSTRACT TRUNCATED AT 250 WORDS)
The operative technique of limited approaches to extramedullary spinal tumours is described. The results after unilateral approaches are as satisfying as after standard laminectomies. The rationale of attempting an unilateral approach is to avoid damage to the dorsal static structures of the vertebral column. Access given by limited approach and possibilities of enlarging the bony defect depending on the topographical situation of the tumour are discussed in detail. It is emphasized that the dura should be opened only over the tumour in order to avoid protrusion of the cord.
In a model of isolated, ventilated and perfused rabbit lungs the influence of a fixed amount of edema (standardized at 7 g weight gain/kg body weight) on the pressure-volume characteristics of the isolated lungs was investigated. Periodical stimulation with A 23187 or A 23187 plus indomethacin or A 23187 plus indomethacin plus glutathione evokes an increase in vascular permeability with subsequent severe alterations of the pressure-volume characteristics, reflecting a disturbance in the alveolar surfactant system, which is more extensive the more rapidly the edema develops. The alterations caused this way are markedly more severe than those caused by the same amount of weight gain due to mechanically increased capillary filtration pressure.
In a model of isolated, ventilated rabbit lungs, perfused with Krebs-Henseleit albumin buffer in a recirculating system, increased availability of free AA (arachidonic acid) results in an increase in pulmonary vascular resistance and permeability. The former can be ascribed to cyclooxygenase products of AA, among which thromboxane A2 is mainly responsible. The increase of vascular permeability is, at least partly, due to lipoxygenase products of AA. Availability of free AA for the different oxygenation pathways can be achieved either by direct application of free AA to the perfusion fluid or by stimulation of AA release from the membrane phospholipid pool by the Ca-ionophore A 23187. The serine proteinase inhibitor gebaxate mesilate in a concentration range between 1 microM and 10 microM and aprotinin in a concentration range between 8 and 200 KIE/ml dose-dependently reduce the increase in vascular resistance after stimulation with A 23187. Correspondingly the increase in vascular permeability due to A 23187 is significantly reduced by gabexate mesilate (5 microM) to 52% and by aprotinin (200 KIE/ml) to 73%. On the contrary the increase in pulmonary vascular resistance and permeability after direct application of free AA to the perfusion fluid is not affected by gabexate mesilate and aprotinin. AA metabolism by cyclooxygenase from ram vesicular gland microsomes is inhibited in vitro by gabexate mesilate and by aprotinin only in very high concentrations (greater than 1mM respectively greater than 2130 KIE/ml). Measurements with porcine pancreas and bee venom phospholipase A2 reveal no influence of aprotinin on these enzymes. Gabexate mesilate inhibits pancreas phospholipase A2 in concentrations more than 10-fold higher than those necessary in the isolated lungs (IC50 = 430 microM), bee venom phospholipase A2 not being affected at all. It is thus apparent that the release of AA from the membrane phospholipid pool rather than any particular step in its oxygenation metabolism is the site of action of these proteinase inhibitors in the pulmonary vascular bed. The possible involvement of an intracellular proteinase is discussed.
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