Longitudinal study of myelin basic protein-specific T-cell receptors during the course of multiple sclerosis

This study analyzed the stability of the myelin basic protein (MBP)-specific T-cell receptor (TCR) repertoire during the course of multiple sclerosis (MS) in three patients who were monitored for three years by gadolinium-enhanced magnetic resonance imaging. Bulk-culture T-cell lines (TCLs) were generated from 3–4 time points for each patient, including times of active and quiescent disease. TCR analysis of these TCLs indicated that both the Vα and Vβ usage was similar over time for each patient. Sequencing of TCRs demonstrated conserved complementarity-determining region 3 (CDR3) sequences within TCLs that expressed the same Vα segment over time, although the Jα usage was different for each TCR. This indicates that the population of MBP-reactive T-cells is changing during the course of MS, but that host and/or environmental factors may be selecting T-cells with particular MHC/peptide binding domains.     

Life satisfaction and active coping style are important predictors of recovery from surgery

OBJECTIVE: The objectives of this study were to investigate the influence of psychological factors on the recovery of surgical patients and to explore whether there are any psychological variables other than anxiety that have a significant influence on recovery from surgery. METHODS: The participants were 112 adult patients undergoing a variety of surgical procedures. On the day prior to surgery, the Freiburg Personality Questionnaire, the State-Trait Anxiety Inventory, a coping schedule and the Questionnaire of Social Support were used to measure psychological parameters including personality, anxiety, coping and social support. The quality of the surgical outcome was rated by two independent and blinded surgeons by the length of hospital stay and analgesia and sedation requirements. The ratings controlled for the diagnosis, type of operation, intraoperative complications, postoperative medical problems and health limitations independent of the surgical procedure. RESULTS: Patients who had a complicated recovery were found to have reduced life satisfaction and lower situation-specific self-control expectations. Structural equation modeling revealed direct relationships between recovery from surgery and personality dimensions with the strongest correlations to life satisfaction, extraversion and attainment orientation. CONCLUSION: The data from this study suggests that valid predictions of the course of postoperative recovery need to take into account personality and coping behaviour orientated data as well as clinical variables. No direct influence on recovery could be predicted from preoperative state anxiety, but it seems likely that state anxiety may influence coping behaviour and that it is this that appears to have a significant impact to surgical recovery.     

Concentration-dependent effects of muscimol to enhance pulsatile GnRH release from GT1–7 neurons in vitro

Immortalized GT1–7 neurons were used to characterize the effect of muscimol, a GABA_A receptor agonist, to enhance pulsatile gonadotropin-releasing hormone (GnRH) release. GT1–7 neurons were grown on Cytodex-3 beads and placed in special superfusion microchambers. The cells were superfused at a rate of 6.2 ml·h⁻¹ with Media 199 (pH 7.35) using a commercially available perfusion system. After a pre-muscimol period of 120 min, the cells were exposed for 5 min to 0.35, 1, 5 or 10 μM muscimol or 5 μM muscimol+20 μM of the GABA_A receptor antagonist, bicuculline. Following removal of the muscimol (and bicuculline, in the case of the latter experiment), the superfusion was continued for another 115 min. Sample fractions were collected at 5 min intervals throughout the perfusion. Basal GnRH release from the GT1–7 neurons was pulsatile with an average interpulse interval of 45.4±0.5 min and an average pulse amplitude of 191.5±22.6 pg·min·ml⁻¹. Our results also demonstrated that the GABA_A receptor agonist, muscimol, enhances pulsatile GnRH release from GT1–7 neurons in culture. The response to muscimol was saturable and concentration-dependent with an EC₅₀ of 0.47 μM. The effects of 5 μM muscimol to increase GnRH pulsatility were blocked by co-exposure to the GABA_A receptor antagonist, bicuculline. The average GnRH interpulse intervals were 41.7±1.8 min, 32.5±2.9 min, 30.6±0.7 min and 25.5±0.4 min in the period following exposure to 0.35, 1, 5 and 10 μM of muscimol, respectively (post-muscimol period). GnRH pulse amplitude (mean-area for each pulse) was increased during exposure to muscimol but not during the pre- or post-muscimol periods. The GABA_A receptor antagonist, bicuculline, itself had no effect on pulsatile GnRH release. These results are consistent with previously published reports suggesting that activation of the GABA_A receptor stimulates hypothalamic GnRH release in embryonic and neonatal animals.     

Plasminogen Activation Without Changes in tPA and PAI-1 in Response to Subcutaneous Administration of Ancrod

Ancrod is a purified fraction of venom from the Malayan pit viper, Calloselasma rhodostoma, currently under investigation for treatment of ischemic stroke. The therapeutic effect is ascribed to a lowering of plasma fibrinogen. Thirty-two healthy volunteers received subcutaneous ancrod at doses of 1.0, 1.5 and 2.0 IU/kg body weight or placebo. Blood samples were drawn before the injection and at various time points until 96 h after the injection. Ancrod leads to the formation of desAA-fibrin, which serves as cofactor in tissue plasminogen activator activity (tPA)-induced plasminogen activation. Unchanged concentrations of prothrombin fragment F1.2 and thrombin–antithrombin complex (TAT) indicate that fibrin formation occurs independent of thrombin. Plasmin generation is independent of an increase in tPA activity or changes in plasminogen activator inhibitor-1 (PAI-1) concentration in plasma. Subcutaneous injection of ancrod leads to a generalized fibrino(geno)lytic response caused solely by providing tPA with soluble fibrin as its cofactor in plasminogen activation. Maximal plasmin activity is present 12 h after subcutaneous injection.     

Evidence of strain differences in GABA-benzodiazepine coupling

The effects of a single dose of oxazepam on seizure threshold, receptor occupancy and brain oxazepam concentration were investigated at several time points after drug treatment in two inbred strains of mice (NIH and C3H/HE). The C3H/HE strain showed a greater sensitivity to the effects of both pentylenetetrazol and oxazepam. Furthermore, the C3H/HE strain showed decreases in both receptor occupancy and seizure threshold across time, whereas the NIH strain showed no change in either measure. Although within-strain correlations were observed between seizure threshold and receptor occupancy, the C3H/HE strain had similar seizure thresholds to the NIH strain throughout but lower percentage receptor occupancies, thus a between-strain correlation was not observed. The C3H/HE strain had a higher number of specific benzodiazepine binding sites and these results may reflect a strain difference in GABA-benzodiazepine receptor coupling. In a further experiment, the development of acute tolerance to the effects of oxazepam was investigated. Brain concentrations of oxazepam and receptor occupancies were determined for each strain of mouse, at two different time points (1.5 and 7.5 h after drug treatment), at which equivalent seizure thresholds were obtained by manipulating the starting dose of oxazepam. For each strain, when equivalent seizure thresholds were observed at different time points, equivalent receptor occupancies were also observed. However, a trend towards higher brain concentrations of oxazepam at the later time point was detected for the two strains, suggesting that there may be some decrease across time in the affinity of the receptor for oxazepam.