[A dust generator for inhalation experiments in a high-pressure chamber]. / Staubherstellung für Inhalationsversuche in einer Uberdruckkammer.

The health effect of inhalable dust particles at working places is predominantly related to "normal" conditions (i.e. temperature = 20 degrees C, atmospheric pressure = 1013 mbar). A probable risk for humans, working in pressurized places (tunnels) raises from modified respiration conditions. An inhalation experiment with rats was performed in a pressurized exposure chamber (1,5 bar). The dust generator was placed in the chamber and consisted of an endless ball-chain, which was lead through a glass-funnel as a dust-store. The average dust concentration ranged between 10 and 14 mg/m3 air. Short-time variations in case of the quartz dust DQ 12 were unavoidable.

[On the preparation of intermediates in cobyrinic acid biosynthesis by suspensions of Propionibacterium shermanii (author's transl)]. / Zur Cobyrinäure-Biosynthese. Gewinnung von Zwischenprodukten der Cobyrinsäure-Biosynthese mit Zellsuspensionen von Propionibacterium shermanii.

The preparation of a dimethyltetrahtdrouroporphyrin (Faktor II or sirohydrochlorin) using suspensions of Propionibacterium shermanii as well as a promising method for the isolation of tetrapyrrols with at least four carboxy substituents from cell-free extracts and growth media are described. Also a Faktor II-analogue with three methyl groups which are derived from L-methionine is reported. Incorporation experiments indicate that this is an intermediate in cobyrinic acid formation. Because of this, and from spectroscopic (field desorptionmass, visible absorption) studies it is concluded that the "extra" methyl group is located at the meso-carbon between two methylated reduced rings.

[On cobyrinic acid biosynthesis. Novel methylated hydroporphyrins and their role in cobyrinis acid formation (author's transl)]. / Zur Cobyrinsäure-Biosynthese. Neuartige, methylierte Hydroporphyrine und deren Bedeutung bei der Cobyrinsäure-Bildung

Clostridium tetanomorphum and Propionibacterium shermanii were examined for intermediates in the synthetic pathway uroporphyrinogen III leads to cobyrinic acid. The isolation of two novel methylated hydroporphyrins, whose methyl groups are derived from S-adenosyl-L-methionine, is described. Spectroscopic (field desorption-mass, visible absorption) und electrophoretic studies as well as incorporation of labelled substrates indicate that they are analogues of a dihyrouroporphyrin and a tetrahydrouroporphyrin with adjacent reduced rings. Field desorption spectra of the [C2H3]- and [CH3]-tetrahydrouroporphyrin analogues show that the compound contains two methyl groups; it is concluded that the chlorine-like compound has one methyl group. Dehydrogenation experiments indicate that the methyl groups are located at one beta-carbon of the reduced rings. Incorporation experiments suggest that the tetrahydrouroporphyrin-like compound is an intermediate in cobyrinic acid biosynthesis. Studies on the utilization of a heptacarboxyporphyrinogen from C. tetanomorphum for cobyrinic acid formation are also described.