Pinosylvin methyl ether deters snowshoe hare feeding on green alder.

Pinosylvin methyl ether (PME), a toxic phenol, is a potent deterrent to showshoe hare feeding on green alder. Concentrations of PME found in green alder parts can account for the low palatability of winter-dormant foliar buds and staminate catkins but cannot affect internode palatability. The lack of a PME-related defense system in internodes suggests that green alder has at least a two-level defense system: defense of growth stages and defense of parts within growth stages.

Fast neutron sensitivities of Geiger-Mueller counter gamma dosemeters.

The sensitivities to 4.2 and 5.5 MeV neutrons of different types of energy-compensated Geiger-Mueller counters used in mixed field dosimetry were measured using a field produced by the 2H(d, n)3He reaction with an isotropic gamma-dose component. Further results are presented on sensitivities to 14.7 MeV neutrons.

Measurement of the fast neutron sensitivities of Geiger-Mueller counter gamma dosemeters.

An associated-particle coincidence technique was used to measure the sensitivity of 14-7 MeV neutrons of three types of energy-compensated Geiger--Mueller counters used in mixed field dosimetry. These were then used to measure the gamma-dose component of a 14-7 MeV neutron flux. The thermal neutron sensitivities were also measured.

Comparison of the fast-neutron sensitivity of a Geiger-Müller counter using different techniques.

The sensitivity of an energy-compensated Geiger-Müller counter to neutrons with approximate energies of 0.6, 5 and 15 MeV, relative to its sensitivity to gamma rays (kU-value), has been determined at different centres in Europe. The time-of-flight, angular difference, associated-particle coincidence and lead filtration technique have been compared, using the same Geiger-Müller counter. For 15 MeV neutrons, a consistent kU-value of 1.9% was obtained. For the lower neutron energies, lower kU values were observed with reasonable agreement.

The response of thermoluminescence dosemeters to fast (14-7 MeV) and thermal neutrons.

The response of common TLD materials has been measured in a 14-7 MeV neutron field with a small and well known gamma component. Values for the thermal neutron response of some TLD materials with low thermal neutron sensitivity have been determined in the NPL standard thermal flux facility.

Hypertension and facial palsy in middle aortic syndrome.

A female infant presented with facial palsy and was found to be severely hypertensive. Plasma renin activity was raised and an angiogram showed middle aortic syndrome. This condition is of unknown aetiology, but positive antineutrophil cytoplasmic antibodies may indicate a vasculitis which heals by intimal fibrosis, causing the observed findings.

Australian lawyers' views on competency issues in older adults.

Lawyers are often called upon by their older clients to draft contracts, make up wills or powers of attorney, or provide other forms of legal advice or service. With the increasing numbers of older people in the population, the numbers of older clients for legal practitioners is likely to increase. Older people are also at increased risk for impaired cognitive processes that can affect their ability to make reasoned judgements in civil contracts and other legal arrangements. Here we report on the results of a survey of 302 Australian solicitors as to their experience and practices in determining the capacity of older clients to make legal decisions. The responses, reflecting a 20.7% return rate, showed a wide range of experience in conducting capacity assessments, with a mean of 15.7 years (SD = 10.59). There was a very wide range of practices in determining capacity with no consensus. The most frequent form of questions older clients were asked related to personal and family history. Less than one-quarter asked for the rationale of the decision: the most appropriate form of question in the literature. The results suggest a need for further training of solicitors in the assessment of the capacity of older clients to make legal decisions.

Mechanism and stereochemical course at phosphorus of the reaction catalyzed by a bacterial phosphotriesterase.

The reaction mechanism for the phosphotriesterase from Pseudomonas diminuta has been examined. When paraoxon (diethyl 4-nitrophenyl phosphate) is hydrolyzed by this enzyme in oxygen-18-labeled water, the oxygen-18 label is found exclusively in the diethyl phosphate product. The absolute configurations for the (+) and (-) enantiomers of O-ethyl phenylphosphonothioic acid have been determined by X-ray diffraction structural determination of the individual crystalline 1-phenylethylamine salts. The (+) enantiomer of the free acid corresponds to the RP configuration. The RP enantiomer of O-ethyl phenylphosphonothioic acid has been converted to the SP enantiomer of EPN [O-ethyl O-(4-nitrophenyl) phenylphosphonothioate]. (SP)-EPN is hydrolyzed by the phosphotriesterase to the SP enantiomer of O-ethyl phenylphosphonothioic acid. The enzymatic reaction therefore proceeds with inversion of configuration. These results have been interpreted as an indication of a single in-line displacement by an activated water molecule directly at the phosphorus center of the phosphotriester substrate. (RP)-EPN is not hydrolyzed by the enzyme at an appreciable rate.

Structure-activity relationships in the hydrolysis of substrates by the phosphotriesterase from Pseudomonas diminuta.

The mechanism and substrate specificity of the phosphotriesterase from Pseudomonas diminuta have been examined. The enzyme hydrolyzes a large number of phosphotriester substrates in addition to paraoxon (diethyl p-nitrophenyl phosphate) and its thiophosphate analogue, parathion. The two ethyl groups in paraoxon can be changed to propyl and butyl groups, but the maximal velocity and Km values decrease substantially. The enzyme will not hydrolyze phosphomonoesters or -diesters. There is a linear correlation between enzymatic activity and the pKa of the phenolic leaving group for 16 paraoxon analogues. The beta value in the corresponding Brønsted plot is -0.8. No effect on either Vmax or Vmax/Km is observed when sucrose is used to increase the relative solvent viscosity by 3-fold. These results are consistent with rate-limiting phosphorus-oxygen bond cleavage. A plot of log V versus pH for the hydrolysis of paraoxon shows one enzymatic group that must be unprotonated for activity with a pKa of 6.1. The deuterium isotope effect by D2O on Vmax and Vmax/Km is 2.4 and 1.2, respectively, and the proton inventory is linear, which indicates that only one proton is "in flight" during the transition state. The inhibition patterns by the products are consistent with a random kinetic mechanism.