Phosphine-imine and -enamido ligands for acceptorless dehydrogenation catalysis.

A highly tunable phosphine-imine ligand family is introduced. Following metallation with ruthenium, deprotonation of the ligand affords a phosphine-enamido species. Complexes with the ligand in both the imine and enamido forms are active toward acceptorless dehydrogenation reactions.

Catalytic cyclization and competitive deactivation with Ru(PR2NR'2) complexes.

The first successful use of the PR2NR'2 (1,5-R'-3,7-R-1,5-diaza-3,7-diphosphacyclooctane) ligand family toward an organic synthesis is described. The precatalysts [Ru(Cp)(PR2NBn2)(MeCN)]PF6 are active toward cyclization of 2-ethynylbenzyl alcohol at low catalyst loading and mild temperatures. Catalyst performance however is limited by both low conscription and by competitive deactivation.

Platelet function in humans is not altered by hyperbaric oxygen therapy.

A pilot survey of platelet function was performed on 6 patients undergoing hyperbaric oxygen therapy (2.0 ATA O2 for 2 hours, 6 days/week) for prophylaxis against osteoradionecrosis. Blood was drawn immediately prior to and after the first, tenth and twentieth treatment for measurements of platelet aggregation, ATP release and expression of activated alphalIb3 integrin. No significant differences were observed due to hyperbaric oxygen exposures.

Ventriculo-peritoneal shunt performance under hyperbaric conditions.

A novice scuba diver with an implanted ventriculo-peritoneal (VP) shunt inquired about the performance characteristics of his shunt while diving. A literature search revealed no information regarding shunt performance under hyperbaric conditions. The manufacturer could not certify that the shunt would function under pressure. Therefore, four VP shunts were tested according to the manufacturer's testing protocol at 1 and 4 atm abs in a multiplace hyperbaric chamber. The pressure (in mm of H2O) required to establish flow through the shunts was recorded. Trials at 1 atm abs (n = 12) and 4 atm abs (n = 12) show that all shunts performed within the pressure range specified by the manufacturer.

A controlled trial of educational strategies to teach medical students brief intervention skills for alcohol problems.

OBJECTIVES: Comparatively little is known about the most effective educational strategies to train medical students to successfully intervene in their patients' alcohol problems. The relative effectiveness of two educational programs to teach medical students brief intervention skills for managing alcohol problems was examined. METHODS: Teaching took place over 3 hr and was either the traditional didactic teaching program on the principles and practice of brief and early intervention or an interactive program involving a shortened lecture, clinical practice, and small group feedback on clinical performance. Students were assessed on a 10-min videotaped encounter with a simulated patient before and after teaching according to how they addressed alcohol-related issues and on their general interactional skills. RESULTS: Performance on alcohol-related issues and interactional skills were significantly improved after teaching, although still poor in terms of clinical performance. A between-groups comparison on pre/ postteaching difference scores indicated interactive training was no more effective than traditional didactic lectures in developing the knowledge and skills needed for a brief alcohol intervention. CONCLUSION: The need for more detailed teaching sessions on sensitive areas such as alcohol use in indicated.

Management and treatment efficacy of drug and alcohol problems: what do doctors believe?

We conducted a survey of the attitudes of postgraduate medical trainees in Australia on the management of drug and alcohol problems and examined the medical practitioner's role in managing drug and alcohol problems, factors influencing prognosis and beliefs about the efficacy of a number of treatment interventions. Of 2461 trainees enrolled in specialty training programmes in internal medicine, psychiatry and general practice 1361 (55%) participated. There was a high level of acceptance of responsibility for management of alcohol and drug problems, with the strongest support observed among psychiatry trainees. However, views of the efficacy of various treatment interventions were less positive. Alcoholics Anonymous was considered to be an approach well supported by the research literature. Dynamic psychotherapy was less well supported, and there was considerable uncertainty about the evidence for brief advice and cognitive-behaviour therapies. The opinions expressed on treatment efficacy were in many cases in striking contrast to the research evidence. The implications for future training in drugs and alcohol in specialty programmes are discussed.

Ultrastructural and biochemical characterization of the epidermal hairs of the seeds of Cuphea procumbens.

Rehydration of desiccated Cuphea seeds results in a rapid morphological change in the seed. Within 20 min thread like epidermal hairs are present on the seed surface. The hairs, which are highly ordered helical structures, are present in the epidermal cells of the desiccated seed. Following emergence the hairs increase in length by means of an eversion process, the mechanism for which is proposed in the text. The hairs were purified to homogeneity and found to be composed of 55% carbohydrate and 45% protein. Following ß-elimination of the carbohydrate using NaOH/NaBH4 one major protein of MW 31,000 was seen upon polacrylamide gel electrophoresis in the presence of sodium dodecylsulphate. The protein, here termed helexin, probably plays a major structural role in determining the helical shape of the hairs.

Electron microscopy of network structures in thermally-induced globular protein gels.

Thin sections of heat-set proteins gels formed from bovine serum albumin, insulin, lysozyme, ribonuclease, and alpha-chymotrypsin, have been studied by transmission electron microscopy. Micrographs have been interpreted as showing protein networks with strands between one and two times as thick as the native protein diameters. Considerable differences in the persistence characteristics, and frequencies of cross-linking, of the strands are observed, and there are variations in network homogeneity over long distances which correlate well with changes in gel opacity caused by alterations in pH and ionic strength. Evidence that artefacts are unlikely to have influenced these interpretations has been obtained in the BSA case in particular, by studying the aggregation process in solution, using alternative microscope approaches such as heavy-metal shadowing and negative staining. assuming that artefacts are absent, gel section micrographs have been simulated by a computer procedure, and the results suggest that, in most cases, the simplest interpretation of the microscope data is in terms of a "string of beads" model for the aggregation process, involving only moderately unfolded, and still globular, protein molecules. Other structural interpretations cannot be ruled out, however, as the degree of protein unfolding, and the exact mode of incorporation of the monomers into the network filaments, cannot be established by the microscope technique alone.

Electron microscopic study of membranes and walls of bacteria and changes occurring during growth initiation.

Thin sections of stationary-phase Streptococcus lactis cells showed that the wall and membrane are 20 and 7 nm thick, respectively. Whole cells were examined by negative staining with ammonium molybdate and by shadowing. On air-drying of whole cells, the membrane pulled away from the wall revealing adhesions between these organelles. Adhesions could not be seen after subculture of the stationary-phase cells into complex media or into solutions containing glucose, KCl, and CaCl(2) in tris(hydroxymethyl)aminomethane buffer. The adhesions were also observed in stationary-phase cells of other gram-positive bacteria. Fractured freeze-etched cells of S. lactis had a smooth outside surface, but the inside of the wall (or outside of the membrane) had a regular structure, repeating at 10 nm, which could correspond to the adhesions observed in the negatively stained air-dried cells. Freeze-etching also revealed holes in the outside wall which had the shape of inverted truncated cones. The outside diameter of the cone was 60 nm, and the diameter on the inside surface of the wall was 20 nm. The membrane had upstanding plugs, 20 nm in diameter, which could fill the holes in the wall.