Nanostructures in various Au ion-implanted ZnO facets modified using energetic O ions.

Noble metal nanoparticles dispersed in semiconductors, mainly in ZnO, have been intensively investigated. Au dispersion and possible precipitation as well as damage growth were studied in ZnO of various orientations, a-plane (112[combining macron]0) and c-plane (0001), using 1 MeV Au-ion implantation with an ion fluence of 1.5 × 10 cm and subsequently annealed at 600 °C in an ambient atmosphere for one hour.

Alanine or pyruvate is required for the development of myotubes from myoblasts and cortisol satisfies this requirement.

Development of myotubes from chick embryo breast muscle myoblasts has been shown to occur in the combined presence of insulin, and both the low and high molecular weight components (LMW, HMW) of chick embryo extract. We report here that alanine, or pyruvate, will replace the LMW component with serine enhancing this effect. In addition, extracts of embryonic kidneys were the most active of five embryonic tissues tested in replacing the LMW component, which led to the finding that cortisol is active in promoting both the development of myotubes and the expression of creatine phosphokinase activity, a muscle-specific indicator of myogenesis.

Strategic positioning: a case study in governance and management.

This case describes the experience of the Detroit Medical Center (DMC) in restructuring its governance and management. It provides a background on the DMC, examines the driving forces that led to modification of its structure, identifies key principles in guiding the change, and describes the strategies and specific steps taken in managing structural change. Finally, the critical lessons learned about leadership style, communication, agenda development, and relations with the board, medical staff, and management are discussed.

Streptonigrin toxicity in Escherichia coli: oxygen dependence and the role of the intracellular oxidation--reduction state.

The bacterial physiology of streptonigrin toxicity was further investigated. An optimal oxygen concentration for toxicity was inferred from data showing that streptonigrin at 5 micrograms/mL was rapidly lethal to aerobic cultures of Escherichia coli K12JF361, but was without effect on anaerobic cultures and was bacteriostatic to cultures inhibited in 5 atm of oxygen plus 1 atm of air (5 atm O2 plus air) (1 atm = 101.325 kPa).

Hyperbaric oxygen toxicity and ribosome destruction in Escherichia coli K12.

The viability of resting suspensions of Escherichia coli K12 Ymel exposed to air plus 300 psi (1 psi = 6.895 kPa) oxygen (hyperbaric oxygen) decreased as an apparent first-order process after an initial period of constant viability. Control suspensions exposed to air plus 300 psi nitrogen (hyperbaric nitrogen) did not lose viability over the 96 h of the experiment.

New chromosomal location for structural genes of ribosomal proteins.

An Escherichia coli mutant, ts9, previously reported by Flaks et al. (Cold Spring Harbor Symp. Quant.

Binding of dihydrostreptomycin to Escherichia coli ribosomes: kinetics of the reaction.

Investigations were carried out on the binding of dihydrostreptomycin to purified (and reassociated) 70S ribosomes and 30S subunits from streptomycin-susceptible strains, and the results were compared with those of similar studies with native (run-off) 70S ribosomes. At 0 C, only a small fraction of purified 70S ribosomes and 30S sub-units bound 1 molecule of the antibiotic tightly, and at a rate comparable to the binding occurring with native 70S ribosomes. At temperatures of 10 C and above, there was a temperature-dependent increase in the extent of antibiotic binding to purified 70S and 30S particles up to a maximum of 1 molecule/ribosomal particle, but the kinetics of binding was slow in comparison to that taking place at 0 C.

Binding of dihydrostreptomycin to Escherichia coli ribosomes: characteristics and equilibrium of the reaction.

The binding of dihydrostreptomycin to ribosomes and ribosomal subunits of a number of different Escherichia coli strains was studied, and the Mg(2+) and pH dependence, as well as the effect of salts and polynucleotides, was determined. The only requirement for binding with ribosomes and subunits from susceptible strains was 10 mm Mg(2+). Monovalent salts weakened the binding in a manner similar to the effects on ribonucleic acid secondary structure, and this was antagonized to some extent by increased amounts of Mg(2+).

Topography of the Escherichia coli 30S ribosomal subunit and streptomycin binding.

Treatment of Escherichia coli 30S ribosomal subunits with trypsin sequentially removes a number of different ribosomal proteins, as revealed by polyacrylamide gel electrophoresis. Proteins that are removed early by trypsin correlate well with those that are added last during reconstitutive assembly of the 30S subunit from 16S ribosomal RNA and the total protein complement. Proteins that are resistant to removal from the subunit by the highest trypsin concentration used correlate with those that are added early during assembly.

Congenital methylmalonic acidemia: enzymatic evidence for two forms of the disease.

Methylmalonic acidemia is an inherited metabolic disorder thus far found in children and characterized by the excessive excretion of methylmalonate in the urine. Typically these children exhibit vomiting, lethargy, ketoacidosis, and failure to grow. Many of the patients are mentally retarded and die early in life.