Effects of variable water motion on regeneration of Hemipholis elongata (Echinodermata, Ophiuroidea)

Abstract. To determine whether increased water motion affects patterns of regeneration in the subtidal burrowing brittlestar Hemipholis elongata (phylum Echinodermata), individuals were subjected to laboratory-controlled turbulence conditions. Half of each replicate aquarium experienced oscillatory (wave-like) turbulence while the other half had no turbulence. Individual brittlestars from which arm-tips had been removed were allowed to burrow and to regenerate. Regenerated arm-tip length and weight were tested for differences between organisms in calm and turbulent conditions. Regenerated arm-tip length differed significantly between control and treatment, but arm-tip dry weight and skeleton/tissue ratio of regenerated arm-tips did not. To quantify plasticity in the skeleton, 15 morphological measurements made on the proximal face of vertebral ossicles (using scanning electron microscopy) were integrated as an index of overall ossicle size. We found a significant difference in the overall size index of the vertebral ossicles between treatments, but could not determine which of the measurements contributed most to the difference. The results indicate that regeneration in H. elongata is a complex process that can be modified by environmental conditions.     

Randomised controlled trial of computer assisted management of hypertension in primary care.

The hypothesis that general practitioners would obtain better outcomes for patients with hypertension using a computer than doctors not using a computer was tested. Sixty family physicians were randomised to two treatment strategies. "Test" physicians completed a data collection form after each visit from a patient with hypertension and mailed the forms to the test centre for processing. Computer feedback on management was mailed to the doctors. This encouraged doctors to apply the "stepped care" protocol, supplied charts of diastolic blood pressure v time, and ranked patients'' diastolic blood pressures by percentile. Letters were mailed to patients to remind them of appointments. "Control" doctors filled out the same data collection forms as test physicians, but neither doctors nor patients received computer feedback. Physicians who used the computer saw more patients per practice than control doctors (test 50 patients, control 40). For all patients the length of follow up was significantly longer in test practices (test 199 days, control 167), and a smaller percentage dropped out of active treatment in test practices (test 37.5%, control 42.1%). For patients with "moderate" hypertension of a baseline diastolic pressure of greater than 104 mm Hg the mean score of the last recorded pressure was below the goal of 90 mm Hg in test practices (88.5 mm Hg), but it failed to reach this goal in control practices (93.3 mm Hg). A greater average reduction of diastolic pressure was achieved in test practices (test 21.7 mm Hg, control 16.7 mm Hg). Though patients with "moderate" hypertension were better controlled in test practices than in control practices, the patients in test practices visited their doctors less often (test 13.3 visits per patient-year, control 17.4 visits). Among patients with newly detected hypertension test practices achieved a greater reduction in diastolic pressure than control practices (test 15.1 mm Hg v control 11.3 mm Hg) and more sustained control of hypertension (test 323 days per patient-year with a diastolic pressure of 90 mm Hg or less v control 259 days).     

Crystal structure of the core domain of RhoE/Rnd3: a constitutively activated small G protein

We report the 2.1 A crystal structure of the core G protein domain of the unusual Rho family member RhoE/Rnd3 in complex with endogenous GTP and magnesium. Unlike other small G proteins, RhoE, along with two other proteins Rnd1/Rho6 and Rnd2/RhoN, does not hydrolyze GTP. The main reason for this is the presence of serines in the positions equivalent to Ala59 and Gln61 in Ras. The structure shows that there are still water molecules in similar positions to the waters thought to be involved in the hydrolysis reaction in other G proteins. The structure suggests three not necessarily exclusive explanations for the lack of hydrolysis. The lack of the conserved glutamine raises the energy of the transition state inhibiting hydrolysis. The serines may restrain the waters from moving closer to the GTP, a step that is required to attain the transition state. They also stabilize the GTP-bound conformation of switch II and could prevent conformational changes required during hydrolysis. By superposition of the RhoE structure on structures of Rho family proteins in complex with binding partners, we make predictions on RhoE interactions with these partners.