Comparison of the effects of heat shock and metal-ion stress on gene expression in cells undergoing myogenesis.

Subjecting 9-day-old quail embryos to an elevated temperature in ovo causes limb, breast, and brain tissues to shift their patterns of protein synthesis from the production of a broad spectrum of different proteins to the new and (or) enhanced synthesis of a small number of heat-shock proteins (HSPs). The HSPs synthesized by undifferentiated breast tissue in ovo (relative masses (Mrs) 88 000, 82 000, 64 000, and 25 000) are similar to those synthesized by explanted breast tissue or by primary cultures of breast myoblasts heat-shocked in culture. Heat-shocked, 120-hour-old myotube cultures synthesize HSPs similar to those detected in heat-shocked myoblasts except that myotubes also exhibit enhanced synthesis of a 55 000 dalton polypeptide and little or no synthesis of a 25 000 dalton HSP; the failure to thermally induce a 25 000 dalton polypeptide in myotubes is related to the fused nature of these cells rather than to their state of differentiation.

The effect of inoculum, culture medium and antimicrobial combinations on the in-vitro susceptibilities of Legionella pneumophila.

The in-vitro susceptibility of 14 strains of Legionella pneumophila to 17 anti-microbial agents were determined. The most active antibiotics were cefoxitin, erythromycin and doxycycline while the least active were cephalothin, cefamandole and cefazolin. Subculturing, type of medium and duration of incubation did not alter the effect of the antimicrobial agents.

Effect of clavulanic acid on minimal inhibitory concentrations of 16 antimicrobial agents tested against Legionella pneumophila.

A total of 15 Legionella pneumophilia isolated were tested against 16 antimicrobial agents used singly and in combination with clavulanic acid. When combined with clavulanic acid, 4 of the 16 antimicrobial agents produced no enhanced effect. However, the minimal inhibitory concentrations of 12 of the antimicrobial agents were reduced by one-half to one-third when in combination with clavulanic acid.

Axoplasmic flow in myelinated and unmyelinated nerves.

[14C]Leucine was injected into the floor of the IVth ventricle of rabbits in order to label the axoplasmic flow of proteins in the efferent fibres of the vagus nerve. At intervals from 6 h to 180 days after injection, the rabbits were sacrificed and the cervical and abdominal vagus and recurrent laryngeal nerves removed. The radioactivity in the protein, lipid and low molecular weight fractions of the nerve segments was estimated by liquid scintillation counting.