Conversion process of chlorine containing polysilanes into silicon carbide

The crystallization of pyrolysed chlorine containing polycarbosilanes (PCS) into silicon carbide is suggested to begin at about 1000 °C by X-ray diffraction experiments. The crystallite size and the crystallite amount were also estimated from the X-ray diffraction patterns. Electron spin resonance, nuclear magnetic resonance and Raman-spectroscopy were used to describe the structure of the material. In addition to these methods a combustion method was used to investigate the carbon and the oxygen contents.     

Metabolic factors have a major impact on kidney allograft survival

BACKGROUND: At the present time, late graft loss is the major cause of kidney failure after transplantation. However, the influence of metabolic factors on this process is ill-defined. METHODS: To identify the impact of lipid metabolism, glucose metabolism, and blood pressure and their prognostic value for graft survival, data for all recipients of a kidney allograft with a potential graft survival of >15 years and a minimum graft survival of 1 month were analyzed retrospectively. Recipients of kidney grafts functioning more than 15 years (n=32) were compared with those with a graft function of less than 10 years (n=152, controls) and evaluated in a multivariate analysis. RESULTS: Low levels of serum cholesterol, triglycerides, and glucose, before and after transplantation, were accompanied by a prolonged graft survival. Prognostic factors for early graft failure included serum triglycerides >300 mg/dl, cholesterol >250 mg/dl before transplantation, serum creatinine >4.0 mg/dl 1 month after transplantation, and donor age above 45 or less than 10 years. Additionally, systolic and, particularly, diastolic blood pressure was lower in the group with a prolonged graft function as compared with controls immediately before and after transplantation. In addition, the incidence of primary graft function was lower and the incidence of acute rejection episodes higher in controls. Cold and warm ischemic time, body mass index, recipient age, and gender did not differ significantly. CONCLUSIONS: Our data suggest that metabolic parameters play an important role in the process of late graft loss after kidney transplantation.     

Direct and GTP-dependent interaction of ADP ribosylation factor 1 with coatomer subunit beta

A site-directed photocrosslink approach was used to elucidate components that interact directly with ADP- ribosylation factor (ARF)-GTP during coat assembly. Two ARF mutants were generated that contain a photolabile amino acid at positions distant to each other within the ARF molecule. Here we show that one of the two positions specifically interacts with coatomer subunit beta both on Golgi membranes and in isolated coat protein complex type I (COPI)-coated vesicles. Thus, a direct and GTP-dependent interaction of coatomer via beta-coat protein complex (COP) with ARF is involved in the coating of COPI-coated vesicles. These data implicate a bivalent interaction of the complex with the donor membrane during vesicle formation.     

Holistic nursing--definition and realization

Single-channel properties of a delayed rectifier voltage-gated K+ channel (I-type) were investigated in peripheral myelinated axons from Xenopus laevis. Channels activated between -60 and -40 mV with a potential of half-maximal activation, E50, at -47.5 mV. Averaged single-channel currents activated with a time delay at all membrane potentials tested. Time to half-maximal activation decreased from 80 to 1.6 msec between -60 and +40 mV. The channel inactivated monoexponentially with a time constant of 10.9 sec at -40 mV. The time constant of deactivation was 126 msec at -80 mV and 16.9 msec at -110 mV. In symmetrical 105 mM K+, the single-channel conductance (gamma) was 22 and 13 pS at negative and positive membrane potentials, respectively, at 13-15 degrees C. In Na+ -rich solution with 2.5 mM extracellular K+ gamma was 7 pS and the reversal potential was negative to -80 mV, indicating a high selectivity for K+ over Na+. gamma depended on extracellular K+ concentration (KD = 19.6 mM) and temperature (Q10 = 1.45). External tetraethylammonium (TEA) reduced the apparent single-channel amplitude at all potentials tested with a half-maximal inhibiting concentration (IC50) of 0.6 mM. Open probability of the channel, but not single-channel current amplitude was decreased by extracellular dendrotoxin (DTX, IC50 = 6.8 nM). mast cell degranulating peptide (MCDP, IC50 = 41.9 microM). In Ringer solution the membrane potential of macroscopic I-channel patches was about -65 mV and depolarized under TEA and DTX. It is concluded that besides their activation during action potentials, I-channels may also stabilize the resting membrane potential.