Investigating the molecule-substrate interaction of prototypic tetrapyrrole compounds: adsorption and self-metalation of porphine on Cu(111).

We report on the adsorption and self-metalation of a prototypic tetrapyrrole compound, the free-base porphine (2H-P), on the Cu(111) surface. Our multitechnique study combines scanning tunneling microscopy (STM) results with near-edge X-ray absorption fine-structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) data whose interpretation is supported by density functional theory calculations. In the first layer in contact with the copper substrate the molecules adsorb coplanar with the surface as shown by angle-resolved NEXAFS measurements. The quenching of the first resonance in the magic angle spectra of both carbon and nitrogen regions indicates a substantial electron transfer from the substrate to the LUMO of the molecule. The stepwise annealing of a bilayer of 2H-P molecules sequentially transforms the XP and NEXAFS signatures of the nitrogen regions into those indicative of the coordinated nitrogen species of the metalated copper porphine (Cu-P), i.e., we observe a temperature-induced self-metalation of the system. Pre- and post-metalation species are clearly discriminable by STM, corroborating the spectroscopic results. Similar to the free-base porphine, the Cu-P adsorbs flat in the first layer without distortion of the macrocycle. Additionally, the electron transfer from the copper surface to the molecule is preserved upon metalation. This behavior contrasts the self-metalation of tetraphenylporphyrin (2H-TPP) on Cu(111), where both the molecular conformation and the interaction with the substrate are strongly affected by the metalation process.

Routine minimal invasive vein harvesting reduces postoperative morbidity in cardiac bypass procedures. Clinical report of 1400 patients.

OBJECTIVE: Minimal invasive endoscopic vein harvesting has not gained widespread acceptance although potential improvements in wound healing and patient comfort are undebatable. The main objections to routine application have been impaired graft quality and prolonged operation time. The feasibility of introducing the minimal invasive approach to vein harvesting into a high volume cardiac bypass surgery program was to be investigated in 1400 patients. METHODS: Our preferred technique is based on standard videoscopic equipment for endoscopic surgery. No disposables are used. The subcutaneous tissue above the saphenous vein is tunnelled by exclusively sharp dissection. No shear stresses are applied to the vein graft or its side branches. Side branches are closed by clips or bipolar coagulation. The differences between endoscopic and conventional surgical vein harvesting with regard to operation time, graft quality, wound healing disturbances and postoperative pain were compared in two groups of 300 concurrently operated patients. Subsequently, a further 1100 patients underwent endoscopic vein harvesting, giving a total experience of 1400 endoscopic procedures. RESULTS: After a learning curve of approximately 100 procedures for an experienced surgeon, harvesting time using minimal invasive techniques was 16 +/- 4 min/graft vs. 10 +/- 2 min for the conventional technique (P < 0.01). Severe wound healing disturbances requiring re-intervention were observed in 0.1% following endoscopic harvesting, moderate wound healing disturbances were observed in 1.7% of patients. By comparison, conventional harvesting led to severe wound healing disturbances in 5% and to moderate disturbances in 8% (P < 0.05). Incidence of peri-operative myocardial infarction as an indirect measure of graft quality was 1.7% with endoscopic vs. 2.3% (n.s.) with conventional technique. Early postoperative mobilisation was faster, pain and need of analgesics were distinctly reduced in patients with endoscopic harvesting. Overall operation time was not significantly prolonged by the described technique. CONCLUSIONS: Minimal invasive endoscopic vein harvesting can be developed into a routine procedure resulting in a lower incidence of wound complications, less postoperative pain and much superior cosmetic results. Graft quality appears to be comparable to standard saphenectomy. There is, however, a higher demand of surgical training and expertise.

Percutaneous dilatational tracheostomy done early after cardiac surgery--outcome and incidence of mediastinitis.

During November 95 to April 97, 45 percutaneous dilatational tracheostomies were performed in a nonselected patient series of 2788 open cardiac surgery cases. Tracheostomy was performed as early as the 2nd postoperative day (median: 6th day), when extubation was not foreseen within the next few days. Duration of intubation was 13 days (mean). We observed 6 complications in 5 patients (13.3%), namely bleeding, misplacement of the tube, subcutaneous emphysema, and superficial infection of the tracheostoma. Mediastinitis and wound infection of the sternal wound did not occur in any single case. There was no death due to tracheostomy. Clinically evident tracheal stenosis and inadequate granulation of the stoma were not observed after extubation. In our opinion, percutaneous dilatational tracheostomy is justifiable, shows good results, and entails minimal risk if done early after cardiac surgery, and it is also superior to standard surgical tracheostomy. Increased incidence of mediastinitis was not seen.

End-expiratory carbon monoxide levels as an estimate of passive smoking exposure aboard a nuclear-powered submarine.

Passive smoking is the involuntary inhalation of tobacco smoke by nonsmokers. The purpose of this study was to estimate the degree of passive smoking exposure sustained by smokers and nonsmokers in a nonventilated submarine through the measurement of end-expiratory carbon monoxide (EECO) levels. The initial and final EECO levels were compared for both smokers and nonsmokers. A simple linear regression equation was then used to compare the initial EECO levels in smokers (and their daily cigarette use) with the postsubmergence EECO levels in nonsmokers. Our results showed the postsubmergence EECO levels in the nonsmoking crew members approximated the initial EECO levels in crew members who smoked 21 cigarettes per day. Nonsmokers in a submerged submarine are exposed to significant levels of CO. Future studies are needed to determine the health consequences of this significantly increased level of exposure in nonsmokers.

[Hypertensive complications in pregnancy--a special evaluation of the Rhineland-Pfalz perinatal study]. / Hypertensive Komplikationen in der Schwangerschaft--eine Sonderauswertung der Perinatalerhebung Rheinland-Pfalz.

In a special analysis of the perinatal database Rheinl.-Pfalz of the years 1989 and 1990 1,876 pregnancies with the risk-factor "gestosis" (2.4% of all deliveries) were evaluated. In comparison to all deliveries (n = 78,250) significantly different incident-rates could be observed: Sterility, working during pregnancy, nationality, parity, psycho-social stress, multiples, adipositas, diabetes mellitus, pathological increase of body weight, urinary infection, number and duration of antenatal hospitalisation. Prematurity and fetal retardation as well as placental insufficiency, pathological antenatal CTG, green amniotic fluid and intrapartel acidosis was seen much more often in the risk group, resulting in a much higher rate of caesarean section (50.1 versus 13.7%) and an increased maternal and fetal morbidity. Perinatal mortality was twice as high in the risk group compared to the control. Thought data quality is limited in this study covering a very larger area, the results underline the unchanged importance of hypertensive disorders in perinatology.