Effect of phenytoin on smoke inhalation injury in sheep

To determine whether the anti-inflammatory effects of phenytoin might reduce cardiopulmonary dysfunction we studied the effects of phenytoin treatment on acute lung injury induced by smoke inhalation. Twenty-one chronically instrumented sheep were observed for 24 h after smoke inhalation injury. Myocardial contractility was evaluated by left ventricular end-systolic pressure-diameter relationship (LVESPDR) with a pair of ultrasonic transducers and strain-gauge transducer. In the control group (n = 6), uninjured sheep were given a bolus of phenytoin (12.5 mg/kg). Smoke-insufflated sheep were divided into nontreatment (n = 7) and phenytoin (n = 8) groups. Phenytoin alone had no effects in uninjured sheep except an early rise in heart rate and LVESPDR. In the group given smoke without treatment, there was a significant increase in pulmonary artery pressure and pulmonary vascular resistance index and a decrease in cardiac index. Pulmonary vascular changes were attenuated by treatment with phenytoin. Pulmonary transvascular fluid flux was evaluated by using a lung lymph fistula. LVESPDR fell in the smoke group but not in the group given phenytoin. There was a marked increase in lung lymph flow with smoke inhalation but this phenomenon was not affected by phenytoin treatment. In conclusion, phenytoin treatment reduced early hemodynamic depression.     

Disturbance of peripheral microvascular function in congestive heart failure secondary to idiopathic dilated cardiomyopathy

OBJECTIVES: Previous studies of peripheral microvascular function in human heart failure have concentrated on changes in flow, and there is little information concerning the impact of heart failure on the principal determinants of transcapillary fluid exchange. This study investigated whether alterations in capillary pressure and microvascular fluid permeability can be detected in subjects with idiopathic dilated cardiomyopathy. METHODS: Finger nailfold capillary pressure and calf capillary filtration coefficient (CFC) were measured in parallel studies of two overlapping groups of 12 non-oedematous subjects with idiopathic dilated cardiomyopathy and mild to moderate heart failure and in age- and sex-matched healthy controls. Capillary pressure was measured by direct cannulation using an electronic resistance feedback servonulling technique, and CFC by mercury-in-silastic strain gauge plethysmography using a modification of the technique which avoids assumptions concerning isovolumetric venous pressure. RESULTS: Following correction for differences in skin temperature, capillary pressure was lower in the subjects with heart failure (P = 0.02). Both CFC and isovolumetric venous pressure were greater in the subjects with heart failure than in controls (3.4 +/- 0.9 vs. 2.6 +/- 0.7 ml.min-1.mmHg-1.100 ml-1, P = 0.03; 27.1 +/- 8.4 vs. 17.2 +/- 7.2 mmHg, P = 0.01). CONCLUSIONS: These data suggest that factors other than changes in arterial inflow and venous outflow pressures are likely to play an important role in the disruption of microvascular homeostasis which occurs in heart failure. Changes in capillary hydraulic conductance may contribute to the pathogenesis of oedema.     

Cloned and expressed rat Ca2+-sensing receptor

We have stably expressed cDNA for the rat brain Ca2+ sensing receptor in Chinese hamster ovary cells. Stimulation of phosphatidylinositol hydrolysis and arachidonic acid (AA) release displayed markedly cooperative responses to Ca2+ with Hill coefficients of 4-5. Both phosphatidylinositol and AA responses were not detected below a threshold of 1.5 mM Ca2+. Mg2+ behaved as a partial agonist with only half the maximal inositol phosphate and AA responses displayed by Ca2+ and with a more shallow concentration-response slope. The potency of Mg2+ in augmenting inositol phosphate and AA responses, in the presence of 1.5 mM Ca2+, implies that serum Mg2+ concentrations attained in clinical conditions will influence the Ca2+-sensing receptor.     

Comparisons of intravaginal and intrauterine insemination of bitches with fresh or frozen semen

To compare the importance of the route of insemination when using fresh or frozen semen, six groups of five bitches were inseminated either into the uterus (groups 4, 5 and 6) or the vagina (groups 1, 2 and 3) with fresh (groups 1 and 4) or frozen semen (groups 2, 3, 5 and 6). The fresh semen was collected when needed from the same dog. The frozen semen used in groups 2 and 5 was obtained from seven dogs on the same day, and pooled and processed simultaneously so that the groups were inseminated with exactly the same semen. The frozen semen used in groups 3 and 6 was obtained from different dogs and processed independently to evaluate not only the effect of the route of insemination but also the potential effect of the dog. The mean concentration of the fresh semen was 310 x 10(6) spermatozoa/ml, its motility was greater than 80 per cent and the percentage of normal live spermatozoa was 80 to 92 per cent. The mean spermatozoal concentration of the frozen semen was 200 x 10(6) spermatozoa/ml, its motility was greater than 60 per cent and the percentage of normal live spermatozoa was 80 per cent. In all the groups there were fewer than 15 per cent abnormal spermatozoa. The animals inseminated with fresh semen received significantly more spermatozoa than the others. The bitches were inseminated twice, three and five days after the estimated peak of luteinising hormone, with a total volume of 5 ml for the vaginal inseminations and 2 ml for the intrauterine inseminations. Sixty per cent of the bitches inseminated with frozen semen and 100 per cent of the bitches inseminated with fresh semen became pregnant, irrespective of the insemination technique used.     

Analysis of Contact and Rupture Behaviour Under Non-Constant Contact Surface Conditions

The present paper addresses the problem of contact between a rigid hemisphere and a thin elastic layer strongly bonded on a rigid plane support, which can be thought of as an adhesive obeying a geometrically non-linear behaviour due to the change of contact area. Using the asymptotic expansion method from a three-dimensional analysis of the layer, a two-dimensional model is derived, under the assumptions of large displacements and small strains. The leading term of the solution of the asymptotic development is such that the displacement field varies linearly through the layer thickness and the stress tensor is constant. A quasi-linear relation is obtained between the area of contact and the penetration of the hemisphere within the layer, and the variation with penetration of the compressive load exerted by the hemisphere is seen to give satisfactory agreement with experiments. In the last part, we present theoretical results concerning the rupture behaviour; the effect of adhesion energy between the hemisphere and the layer on the radius of curvature at the rupture point between both solids is assessed. Further, the thickness of an hypothetical interphase through which failure propagates is determined theoretically.     

Single-crystal neutron diffraction: a valuable tool for probing bond activation in transition metal σ complexes

Transition metal complexes are ubiquitous intermediates in metal-catalyzed reactions, including hydrogenations, activation and functionalization reactions of hydrocarbons, and hydroborations. For over 20years, single-crystal neutron diffraction has been exploited to investigate bond activation in these systems. Topics investigated include H–H activation in H2 complexes, C–H activation in agostic systems and, most recently, B–H activation in a catecholborane metal complex. These results are illustrated here drawing upon studies carried out at both pulsed neutron sources and steady-state reactors. Despite notable successes such as those that we highlight, however, single-crystal neutron diffraction has seen somewhat limited application here to date primarily due to the need for large crystals. Revolutionary improvements are anticipated with the advent of a new generation of sources including the Spallation Neutron Source (SNS) that is scheduled to become operational at Oak Ridge, TN in 2006. At the SNS, it will be possible to work with crystals approaching the size commonly used in X-ray studies employing laboratory sources and to greatly expand the range of materials that are open to investigation.*To whom correspondence should be addressed.     

Rapid measurements of elastic modulus and density in polypropylene sheet during aging

New methods for rapidly obtaining elastic modulus and density measurements during isothermal polymer aging are given. The elastic measurements are performed using a Rockwell hardness tester. In this case, the elastic recovery is measured. Rapid density measurements are performed using a “double drop” density gradient columan method. Here, a fully aged and a freshly quenched specimen are dropped simultaneously into the column. Simultaneous column height differences directly measure the density difference of the two specimens. The results of these two experiments extend previously reported aging measurements to relatively low times of aging. A log (time) law for both properties is found to the smallest times measured.