Structural properties of DNO investigated with pyrene excimer formation.

Four diamino acid-Nalpha-substituted oligopeptide (DNO) oligomers substituted with pyrenyl as photophysical probes were synthesized. The excimer formation and ground-state association of the pyrenyl groups were investigated by means of absorption and steady-state fluorescence spectroscopy together with time-resolved fluorescence techniques. The photophysical parameters obtained from the different derivatives reflect the secondary structural properties of the DNO backbones.

Continuous flow-resonance Raman spectroscopy of an intermediate redox state of cytochrome C.

An intermediate redox state of cytochrome c at alkaline pH, generated upon rapid reduction by sodium dithionite, has been observed by resonance Raman (RR) spectroscopy in combination with the continuous flow technique. The RR spectrum of the intermediate state is reported for excitation both in the (alpha, beta) and the Soret optical absorption band. The spectra of the intermediate state are more like those of the stable reduced form than those of the stable oxidized form. For excitation of 514.5 nm, the most prominent indication of an intermediate state is the wave-number shift of one RR band from 1,562 cm-1 in the stable oxidized state through 1,535 cm-1 in the intermediate state to 1,544 cm-1 in the stable reduced state. For excitation at 413.1 nm, a band, present at 1,542 cm-1 in the stable reduced state but not present in the stable oxidized state, is absent in the intermediate state. We interpret the intermediate species as the state where the heme iron is reduced but the protein remains in the conformation of the oxidized state, with methionine-80 displaced as sixth ligand to the heme iron, before relaxing to the conformation of the stable reduced state, with methionine-80 returned as sixth ligand.

Time-resolved resonance Raman spectroscopy of cytochrome c reduced by pulse radiolysis.

The first investigation of the dynamics of a redox transition of an electron-transfer enzyme by time-resolved resonance Raman spectroscopy in combination with pulse-radiolytic reduction is described by an application to cytochrome c. A long-lived transient state is observed upon reduction of the alkaline form of cytochrome c as a distinct frequency shift of one resonance Raman band. From the frequency in the stable oxidized state, 1567 cm(-1), this particular resonance Raman band shifts within less than 1 microsecond to 1533 cm(-1) in the transient reduced state, which has a lifetime longer than 20 ms but shorter than a few seconds. Finally, in the stable reduced state, this band is located at 1547 cm(-1). According to a previous normal coordinate analysis, this resonance Raman band can be assigned predominantly to a stretching mode of the outermost C-C bonds in the four pyrrole rings of porphyrin. This vibrational mode is influenced by the protein most directly through the covalent thioether linkages of two cysteines to porphyrin. We interpret the long lifetime of the transient state as due to the slow return of Met-80 as sixth ligand to the heme iron upon reduction of the alkaline form of cytochrome c.

Electro-optical multichannel spectrometer for transient resonance Raman and absorption spectroscopy.

An optical multichannel system is described, used for time-dependent absorption measurements in the gas phase and the liquid phase and for resonance Raman spectroscopy of short-lived transient species in the liquid phase in pulse radiolysis. It consists of either an image converter streak unit or an image intensifier coupled to a TV camera with computerized data handling. The system enables the recording of time-dependent absorption spectra or resonance Raman spectra of short-lived radicals and excited states with single electron and light pulses.

[Filtration and irradiation of the dialysis fluid to prevent bacteriemia during hemodialysis (author's transl)]. / Entkeimung der Dialyselösung durch Filtration oder Bestrahlung.

For prevention of bacteriemia caused by contaminated dialysis fluid it is necessary to protect the dialysator by decontamination of the fluid immediately before entering the dialysator. Using filters with a pore size of 0.2 micrometer or 0.45 micrometer sterile samples of dialysis fluid could be obtained, but flow rate and pressure of the fluid could not be kept constant, when the resistance of the filter increased during use. With UV-lamps no problems concerning flow rate or pressure were encountered, but really satisfying results emerged only in laboratory experiments. This was due to causes which can be influenced by technical improvements of the irradiation unit, while the use of filters implies additional measures at the monitor unit to control flow rate and pressure. The success of the applied antimicrobial techniques should be monitored for not inducing a false conviction of safety.

[Primary malignant nephrosclerosis (author's transl)]. / Primäre maligne Nephrosklerose

Primary malignant nephrosclerosis shows a haemolytic-uraemic symptomatology and can be differentiated from secondary malignant nephrosclerosis on clinical and histological grounds. The disease was observed in 4 patients: a 25-year-old man and 3 women aged 19, 28 and 49 years. The disease is characterized by a fulminating course, malignant hypertension with progressive retinopathy, and development of progressive renal failure with subsequent irreversible anuria. In addition haemolytic anaemia or posthaemolytic states as well as consumption coagulopathy occur. In 2 cases schizozytes and in particular helmet-shaped forms could be demonstrated. On histology an obliterating necrotizing vascular change is seen which is limited to the kidneys as was demonstrated in one case by angiography. Therapeutic attempts included antibiotics, steroids, heparin, streptokinase, antihypertensive drugs, and haemodialysis. The 3 female patients died, the man survived after bilateral nephrectomy.