Assessments of thrombogenicity by three in vitro techniques. Student Research Award in the Undergraduate, Master Candidate, or Health Science Degree Candidate Category, 21st annual meeting of the Society for Biomaterials, San Francisco, CA, March 18-22, 1995

This study assessed three in vitro techniques designed to measure the thrombogenicity of vascular grafts. All techniques immersed vascular grafts in rotating blood. In the gravimetric analysis, the weight of adherent thrombi was recorded at 2 min intervals for 20 min. In the torque analysis, a microviscometer continuously recorded the amount of torque developed as the graft rotated for 20 min. In the thrombin analysis, the blood sample was analyzed for fibrinopeptide A production indicating fibrinogen cleavage. Expanded polytetrafluoroethylene grafts were treated by removal of air nuclei (denucleation), binding of heparin, or binding of polyethylene oxide (PEO). The gravimetric analysis determined that the time at which each group experienced clot initiation was as follows: control after 6 min, denucleation after 14 min, heparin after 18 min, and PEO after 10 min. Similarly, in the torque analysis all treatment groups significantly delayed the initial increase in torque from 8.0 min for control to 12.5 min for denucleation (P < .01), > 20 min for heparin (P < .01), and 12 min for PEO (p < .05). The thrombin analysis determined that coagulation activity was reduced relative to control at 12 min with the denucleation group (P < .05) and heparin group (P < .01) and at 18 min with all treatment groups (P < .01). The similarity of results among the techniques increases confidence that each measurement accurately predicts in vitro thrombogenicity.     

2-Phenyl-4-(aminomethyl)imidazoles as potential antipsychotic agents. Synthesis and dopamine D2 receptor binding

A series of 2-phenyl-4-(aminomethyl)imidazoles were designed as conformationally restricted analogs of the dopamine D2 selective benzamide antipsychotics. The title compounds were synthesized and tested for blockade of [3H]YM-09151 binding in cloned African green monkey dopamine D2 receptor preparations. The binding affinity data thus obtained were compared against that of the benzamides and a previously described series of 2-phenyl-5-(aminomethyl)-pyrroles.     

Ethanol increases GABAA responses in cells stably transfected with receptor subunits

Ethanol enhancement of GABAA receptor function has been found in some, but not all, studies. These results suggest the existence of ethanol-sensitive and -resistant receptors that may differ in subunit composition, although methodological differences (e.g., 36Cl- flux versus membrane currents) could also contribute to the different results. To examine these possibilities, we used mouse L(tk-) cells stably transfected with alpha 1 + beta 1 or alpha 1 + beta 1 + gamma 2L GABAA receptor subunit DNAs and compared 36Cl- flux with whole-cell, patch-clamp measurements of GABAA receptor function. Both techniques detected a similar modulation of the GABA receptor by ethanol, flunitrazepam, and pentobarbital. The potentiating action of ethanol required the gamma-subunit and was maximal at a concentration of 10 mM. Similar ethanol potentiation was obtained with brief (20 msec) or long (2 sec) applications of GABA. Analysis of data obtained from individual cells expressing alpha 1 beta 1-gamma 2L subunits showed considerable variability in sensitivity to ethanol, particularly with concentrations of 30 and 100 mM. Ethanol potentiated GABA action if the cells were grown on coverslips coated with polylysine, but had no effect on GABAA receptors of cells grown on uncoated coverslips. Thus, ethanol action was influenced by the growth matrix. Taken together, these data indicate that a gamma-subunit is necessary, but not sufficient, for ethanol sensitivity in this cell system. We suggest that posttranslational processing, particularly receptor phosphorylation, may also be important and that stably transfected cells will be useful in elucidating these events.     

Detection of a novel mutation at amino acid position 614 in the ryanodine receptor in malignant hyperthermia

Postural alignment is not an inherent trait. Proper alignment is acquired through training postural muscle groups. This training is based on scientific principles associated with improving the physiological parameters of muscle mechanics. The purpose of this report is to describe and demonstrate the application of exercise physiology training principles to the improvement of postural alignment, which may enhance vocal performance. Specific exercise principles are explained and key concepts highlighted. Selected exercises for training postural muscles are presented to assist in establishing techniques that result in the expected adaptations. The application of training principles to postural muscles has been shown to improve postural alignment by strengthening synergistic muscles and establishing a balance between the agonistic and antagonistic activity of these muscles. Since posture has been well established as an important component of vocal performance, the application of these principles to vocal training seems to warrant the attention of vocal trainers and performers.     

How much hydration is necessary for the stabilisation of DNA-duplex?

A combination of NOESY and ROESY experiments show that the higher stabilities (T(m)) of phenazine tethered matched (2) and G-A mismatched (4) DNA duplexes are due to the decrease of the exchange-rate (i.e. increase of the life-time) of the imino-protons and the reduced water activity in their minor grooves compared to their non-tethered counterparts (1) and (3).     

Adenosine-5'-tetraphosphate and guanosine-5'-tetraphosphate: new substrates of the cytosolic exopolyphosphatase of the yeast Saccharomyces cerevisiae

A cytosolic preparation of Saccharomyces cerevisiae is capable of hydrolyzing adenosine-5'-tetraphosphate and guanosine-5'-tetraphosphate with activities which are 1.5-2 times greater than that with polyP15. The apparent K(m) values for hydrolysis of adenosine-5'-tetraphosphate and guanosine-5'-tetraphosphate are 100 and 80 microM, respectively. A comparative study of inhibitors shows that these activities are inherent characteristics of these exopolyphosphatases.     

Molecular-biologic aspects of interaction between nervous and immune systems

The problem of the neuro-immuno interactions on the level of the protein trans-factors, stimulating interleukin-2 (IL-2) gene expression was discussed. The physico-chemical and functional parameters of the low molecular nuclear proteins (SP and BP- 14, 18, 19 kDs) isolated from splenic and brain cells of immunized rats were studied. The binding of these proteins to the regulatory region of IL-2 gene in vitro and stimulation of the IL-2mRNA synthesis in splenic T-lymphocytes culture in normal conditions were shown. The protective effect of SP and BP on the IL-2mRNA synthesis in stressful conditions and by the T-cells treatment with the CsA was demonstrated.