Sodium currents in mammalian muscle

1. A method is described which allows the approximate computation of membrane current from measurements with three electrodes in the mid-region of a muscle fibre.     

Sedative but not anxiolytic properties of benzodiazepines are mediated by the GABA(A) receptor alpha1 subtype

Inhibitory neurotransmission in the brain is largely mediated by GABA(A) receptors. Potentiation of GABA receptor activation through an allosteric benzodiazepine (BZ) site produces the sedative, anxiolytic, muscle relaxant, anticonvulsant and cognition-impairing effects of clinically used BZs such as diazepam. We created genetically modified mice (alpha1 H101R) with a diazepam-insensitive alpha1 subtype and a selective BZ site ligand, L-838,417, to explore GABA(A) receptor subtypes mediating specific physiological effects. These two complimentary approaches revealed that the alpha1 subtype mediated the sedative, but not the anxiolytic effects of benzodiazepines. This finding suggests ways to improve anxiolytics and to develop drugs for other neurological disorders based on their specificity for GABA(A) receptor subtypes in distinct neuronal circuits.     

Peripheral blood lymphocytes from thermal injury patients are defective in their ability to generate lymphokine-activated killer (LAK) cell activity

We have previously shown that natural killer (NK) cell activity against K562 tumor cells is severely depressed in thermal injury patients. In this study we have investigated whether the low NK cell activity present in peripheral blood lymphocytes (PBL) from thermal injury patients could be enhanced byin vitro culture with interleukin 2 (IL2) and whether PBL obtained from these patients could generate lymphokine-activated killer (LAK) cell activity against NK insensitive tumor targets. NK cell activity in PBL obtained from 12 different patients was greatly enhanced against K562 tumor cells afterin vitro culture with IL2 for 3 days. In contrast, PBL obtained from these patients and incubated with IL2 had little to no cytotoxic activity when measured against a number of NK-insensitive tumor targets. The failure of PBL obtained from thermal injury patients to generate LAK cell activity was observed regardless of the culture time or the amount of IL2 added to the cultures. PBL from thermal injury patients demonstrated reduced proliferative responses to IL2 and, more importantly, contained suppressor cells which could inhibit the generation of LAK cell activity of normal PBL obtained from control individuals. These results clearly show that in some thermal injury patients NK cell activity can be enhanced by IL2 but these patients are defective in their ability to generate LAK cell activity.     

Antigenic variation in alkaline deoxyribonuclease induced by three different strains of Epstein-Barr virus

To determine whether biological and/or biochemical variants exist between strains of Epstein-Barr virus (EBV), we superinfected Raji cells with the nontransforming lytic strain of EBV (HR-1), and two isolates that both transform B-lymphocytes and superinfect Raji cells, B95–8, and NPC-EBV. The superinfected cells were assayed for EBV specific DNase. A new electrophoretic form of DNase was observed in cells superinfected with B95-8 EBV as compared to the enzymes induced by the HR-1 and NPC-EBV isolates. There were antigenic differences in the DNase induced by the EBV strains. Since antibody to EBV DNase is a marker for nasopharyngeal carcinoma (NPC), these data may have implications for EBV-associated disease.     

A microsatellite-based,physically anchored linkage map for the gray,short-tailed Opossum (<Emphasis Type="Italic">Monodelphis domestica</Emphasis>)

The genome of the gray, short-tailed opossum, Monodelphis domestica, will be the first of any marsupial to be fully sequenced. The utility of this sequence will be greatly enhanced by construction and integration of detailed genetic and physical maps. Therefore, it is important to verify the unusual recombinational characteristics that were suggested by the ‘first-generation’ M. domestica linkage map; specifically, very low levels of recombination and severely reduced female recombination, both of which are contrary to patterns in other vertebrates. We constructed a new linkage map based on a different genetic cross, using a new and much larger set of map markers, and physically anchored and oriented the linkage groups onto chromosomes via fluorescence in-situ hybridization mapping. This map includes 150 loci in eight autosomal linkage groups corresponding to the eight autosome pairs, and spans 86–89% of the autosomal genome. The sex-averaged autosomal map covers 715 cM, with a full-length estimate of 866 cM; the shortest full-length linkage map reported for any vertebrate. The sex-specific maps confirmed severely reduced female recombination in all linkage groups, and an overall F/M map ratio =  0.54. These results greatly extend earlier findings, and provide an improved microsatellite-based linkage map for this species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Physiological and Psychological Effects of Delivering Medical News Using a Simulated Physician–Patient Scenario

We examined the acute stress response associated with having to deliver either bad or good medical news using a simulated physician–patient scenario. Twenty-five healthy medical students were randomly assigned to a bad medical news (BN), a good medical news (GN), or a control group that read magazines during the session. Self-report measures were obtained before and after the task. Blood pressure and heart rate were measured throughout the task period. Four blood samples were obtained across the task period. The BN and GN tasks produced significant increases in self-reported distress and cardiovascular responses compared with the control group. There was also a significant increase in natural killer cell function 10 min into the task in the BN group compared with the control group. The BN task was also somewhat more stressful than the GN task, as shown by the self-report and cardiovascular data. These findings suggest that a simulated physician–patient scenario produces an acute stress response in the physician, with the delivery of bad medical news more stressful than the delivery of good medical news.     

The So-Called Borderline Patient: Aetiology,Diagnosis, and Treatment

This short paper examines the relationship between borderline psychopathology and various theories regarding the aetiology of this disorder. In the formation of borderline personality organization, distinct structural alterations in personality development are thought to arise from both genetic/neurobiological and environmental/trauma factors. We concur that these variables are instrumental in the formation of borderline personality organization. However, we believe that genetic/neurobiological variables are more closely related to developmental deficits, whereas environmental/trauma factors are primarily associated with either arrested development or regressive phenomenon. Regardless of aetiology, the resultant borderline personality organization disorders may present with comparable symptoms. Further, we hypothesize that the prognosis for response to treatment is related primarily to whether the borderline disorder arises from developmental deficits, arrested development, or regressive phenomena. Diagnostic indicators and treatment considerations for each of the borderline aetiologies are presented.