Discriminative stimulus properties of ethanol in the rat: differential effects of selective and nonselective benzodiazepine receptor agonists

Rats were trained to discriminate between ethanol (1.0 g/kg; 10% v/v) and saline under a fixed ratio 10 schedule of sweetened milk reinforcement. Both diazepam [nonselective, full benzodiazepine (BZ) receptors agonist] and bretazenil (nonselective, partial BZ receptor agonist) produced dose-dependent ethanol-appropriate responding (>75%). Neither diazepam nor bretazenil affected the response rate at the doses producing maximal generalisation from ethanol. In contrast, zolpidem (full BZ1 receptor agonist) and abecarnil (full BZ1/full or partial BZ2 receptor agonist) produced only moderate (<50%) ethanol-appropriate responding when tested up to doses that markedly decreased the overall response rate. These results suggest that: 1) there are no major differences between full and partial, nonselective BZ receptor agonists in their ability to substitute for 1.0 g/kg dose of ethanol; 2) stimulation of BZ1 receptors alone is not sufficient to produce ethanol-like discriminative stimulus effects in the rat.     

Large-signal phase retardation with a poled electrooptic fiber

A linear electrooptic coefficient of 0.3 pm/V is induced in a germanosilicate fiber by thermal/electric-field poling. Reducing the fiber thickness by simple mechanical polishing following the poling, leads to a half-wave drive voltage of only 75 V for a 12-cm active length with no measurable linear optical loss in the fiber. The induced linear electrooptic coefficient shows no decay at room temperature for over four months, and only a 10% decay after heating to 90/spl deg/C for 1000 h.     

Stability of proximal femoral grafts in canine hip arthroplasty

In a canine model, the fixation stability of a prosthesis and proximal bone graft composite were measured relative to the distal femur. One group had the prosthesis graft composite cemented into the distal femur. The second group had the prosthesis graft composite press fit into the distal femur for biologic ingrowth. Displacements of the proximal femoral grafts relative to the host bone in each group were measured after ex vivo (acute with graft) implantation and 4 months after implantation. A third group with no osteotomy (acute intact) simulated perfect graft to host bone union. Relative displacements representing 6 degrees freedom (translation and rotation) were calculated from the displacement values measured by 9 eddy current transducers. Measurements of displacement were used to test the hypothesis that distal press fit fixation equals distal cement fixation at 4 months after implantation. In all cases the measured translations and rotations of the graft to implant construct were small and of a magnitude that should encourage bone ingrowth (< 0.05 mm and < 0.1 degree, respectively). The stability of the press fit group at 4 months was not significantly different from the cemented group in axial and transverse displacement during axial and transverse loading, respectively. There was no difference in stabilities at 4 months between distal press fit and cemented fixation in hip replacements requiring a proximal femoral graft.     

Near Shannon limit performance of low density parity check codes

The authors report the empirical performance of Gallager's low density parity check codes on Gaussian channels. They show that performance substantially better than that of standard convolutional and concatenated codes can be achieved; indeed the performance is almost as close to the Shannon limit as that of turbo codes     

Synovial cyst and degeneration of the transverse ligament: an unusual cause of high cervical myelopathy. Case report

A case of cystic degeneration of the transverse ligament located posteriorly to the dens and causing compression to the lower medulla and upper cervical spinal cord is reported. The clinical, pathological, and radiological findings are described and compared to the literature to characterize this syndrome more fully. The advantages of a posterolateral surgical approach are stressed.     

Epitope cleavage by Leishmania endopeptidase(s) limits the efficiency of the exogenous pathway of major histocompatibility complex class I-associated antigen presentation

The activation of CD8+ T cell responses is commonplace during infection with a number of nonviral pathogens. Consequently, there has been much interest in the pathways of presentation of such exogenous antigens for major histocompatibility complex class I-restricted recognition. We had previously shown that Leishmania promastigotes transfected with the ovalbumin (OVA) gene could efficiently target OVA to the parasitophorous vacuole (PV), with subsequent recognition by class II-restricted T cells. We now report the results of studies aimed at evaluating the PV as a route of entry into the exogenous class I pathway. Bone marrow-derived macrophages can present soluble OVA (albeit at high concentrations) to the OVA(257-264)-specific T cell hybridoma 13.13. In contrast, infection with OVA-transfected Leishmania promastigotes failed to result in the stimulation of this hybridoma. This appeared unrelated to variables such as antigen concentration, parasite survival, and macrophage activation status. These results prompted an analysis of the effects of promastigotes on class I peptide binding using RMA-S cells and OVA(257-264). Our data indicate that the major surface protease of Leishmania, gp63, inhibits this interaction by virtue of its endopeptidase activity against the OVA(257-264) peptide. The data suggest that this activity, if maintained within the PV, would result in loss of the OVA(257-264) epitope. Although we can therefore draw no conclusions from these studies regarding the efficiency of the PV as a site of entry of antigen into the exogenous class I pathway, we have identified a further means by which parasites may manipulate the immune repertoire of their host.     

The analysis of general axially symmetric antennas with a coaxialfeed line by the method of lines

The use of the method of lines in the analysis of various circular antennas-circular patch antennas and various forms of monopoles is proposed and substantiated. The antennas considered are fed by coaxial lines. Impedance/admittance transfer procedures are developed, which allow to calculate the antenna input impedance by a successive transfer from the aperture through the different sections. The described relations are also useful for other applications     

Effect of vitamin E and mannitol on renal calcium oxalate retention in experimental nephrolithiasis

STUDY OBJECTIVE: To assess the efficacy of laser laparoscopic photocoagulation of endometriomas (2-18 cm) in patients with pain, infertility, or a combination of the two. DESIGN: Retrospective review of all patients with endometriomas from June 1, 1983, to December 31, 1993. SETTING: Department of gynecology and obstetrics at a district general hospital and national training center in minimal access surgery. PATIENTS: One hundred sixty-five women with large endometriomas present at the time of laser laparoscopy. INTERVENTIONS: Carbon dioxide laser or potassium-titanyl-phosphate laser laparoscopic surgery. MEASUREMENTS AND MAIN RESULTS: Ninety (74%) of 122 patients reported improvement or resolution of pain; and 30 of 66 achieved a pregnancy, for a cumulative conception rate of 45%. CONCLUSION: Laser laparoscopy is a practical, safe, and effective technique for the management of large ovarian endometriomas.