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The aim of the present study was to develop methods for the rapid assessment of intimal quality of coronary bypass segments of venous origin, and to prevent endothelial damage by improved intraoperative handling of graft segments. Particular attention was paid to the influence of the composition of the preservation solution and the intravasal filling pressure on the degree of endothelialization. Intrava-sal exposure to Alcian blue at pH<3 resulted in highly specific staining of intimal regions with functionally or structurally damaged endothelium. Standardization of preparation, staining and image acquisition of the intimal surface of graft remnants and subsequent computer-aided planimetry of these images made it possible for the first time to perform rapid serial investigations for quality control of bypass grafts. Using saline as the rinsing and intraoperative storage medium resulted in the loss of more than 50% of the endothelium at intravasal pressures of 0-100 mmHg. Increasing the pressure resulted eventually in complete de-endothelialization. In contrast, grafts incubated in a customized plasma derivative tolerated pressures of up to 200 mmHg with no significant endothelial loss; and even after exposure to 1,000 mmHg (10 times the average mean arterial pressure!) more than 70% of the endothelium were intact and vital. These findings imply strongly that the quality of aortocoronary bypass grafts of venous origin can be improved substantially by the use of a plasma derivative solution for intraoperative preservation and by monitoring and controlling the intravasal pressures reached during sealing and storage.

Objective: Laryngomalacia is the most common cause of stridor in newborns and infants. The aim of the contribution was to present objectified data of the outcome of transoral CO(2) laser microsurgery in patients with laryngomalacia utilizing polysomnography (PSG)., Patients and Methods: This retrospective study comprised 21 patients who were diagnosed to suffer from laryngomalacia. Diagnosis was confirmed by pharyngo-laryngoscopy under spontaneous breathing. If there was evidence for laryngomalacia a transoral CO(2) lasersurgical intervention and/or epiglottopexy was performed in the same session. 8 patients, on whom the following should be focused, received pre- and postoperative PSG which was performed for efficiency control of the applied treatment., Results: All 21 patients underwent invasive treatment for laryngomalacia (lasersurgical division of the aryepiglottic folds: n=13; epiglottopexy: n=5; combined procedure: n=3). All patients were successfully extubated after surgery. In 20/21 cases breathing improved clearly after one single intervention. Stridor disappeared completely in the further course of the disease. In the 8 patients who received pre- and postinterventional PSG, lasersurgical interventions were performed. Statistical analysis of pre- and postoperative PSG revealed that MOAI/h (mixed obstructive apnea index/hour) improved significantly (p=0.016, Wilcoxon-Signed-Rank Test). Also desaturation/hour improved in the postoperative course (p=0.11)., Conclusion: The presented concept describes an effective and reliable approach for diagnostics and treatment for laryngomalacia. To objectify the success of supraglottoplaty in patients suffering from severe laryngomalacia a pre- and postoperative PSG seems to be useful and advisable. The present results of PSG demonstrate that children with laryngomalacia to benefit from lasersurgical division of the aryepiglottic folds and/or epiglottopexy. This fact is supported by the postoperative improved clinical aspect.

The soluble [NiFe]-hydrogenase (SH) of the facultative lithoautotrophic proteobacterium Ralstonia eutropha H16 has up to now been described as a heterotetrameric enzyme. The purified protein consists of two functionally distinct heterodimeric moieties. The HoxHY dimer represents the hydrogenase module, and the HoxFU dimer constitutes an NADH-dehydrogenase. In the bimodular form, the SH mediates reduction of NAD(+) at the expense of H(2). We have purified a new high-molecular-weight form of the SH which contains an additional subunit. This extra subunit was identified as the product of hoxI, a member of the SH gene cluster (hoxFUYHWI). Edman degradation, in combination with protein sequencing of the SH high-molecular-weight complex, established a subunit stoichiometry of HoxFUYHI(2). Cross-linking experiments indicated that the two HoxI subunits are the closest neighbors. The stability of the hexameric SH depended on the pH and the ionic strength of the buffer. The tetrameric form of the SH can be instantaneously activated with small amounts of NADH but not with NADPH. The hexameric form, however, was also activated by adding small amounts of NADPH. This suggests that HoxI provides a binding domain for NADPH. A specific reaction site for NADPH adds to the list of similarities between the SH and mitochondrial NADH:ubiquinone oxidoreductase (Complex I).

Molecular hydrogen is widely used by microorganisms as a source of energy. One of the best studied aerobic hydrogen oxidizers, the beta-proteobacterium Ralstonia eutropha (formerly Alcaligenes eutrophus), harbors two distinct [NiFe]-hydrogenases which catalyze the heterolytic cleavage of H2 into 2H+ and 2e-. The genes encoding the hydrogenase subunits are arranged in two large operons together with accessory and regulatory genes involved in hydrogenase biosynthesis. Both operons are transcribed from strong sigma54-dependent promoters. Transcription requires the activation by the HoxA protein, a member of the NtrC family of response regulators. HoxA is only active when H2 is present in the environment. H2 recognition is mediated by a signal transduction complex consisting of the soluble histidine protein kinase HoxJ and a regulatory [NiFe]-hydrogenase which acts as an H2 receptor. Biochemical and genetic data suggest that signal transduction between the RH and HoxJ involves an electron transport process. According to our current model the histidine protein kinase HoxJ inactivates HoxA by phosphorylation in the absence H2. This property of the HoxJ-HoxA regulator pair is quite different from the behaviour of common two-component regulatory systems. Phosphorylation of HoxA is blocked in the presence of H2 provided the RH can contact HoxJ and transmit the signal to the kinase. Furthermore, hydrogenase gene expression is subject to a global regulatory network in response to the carbon and energy source. HoxA is a major component of this epistatic control the molecular mechanism of which is not yet understood.