Pharmacodynamic effects of vecuronium: A dose response study

Vecuronium was administered to patients in dosages of 0.1, 0.2, 0.3, and 0.4 mg/kg to determine the clinical efficacy of large doses of vecuronium. Onset times shortened with larger doses up to 0.3 mg/kg. With 0.4 mglkg, however, there was no significant improvement in onset time and the duration of action became unpredictable and often prolonged. Mean onset times were 172, 138, 106, and 100 seconds for the four groups, respectively. Prolonged duration of action (43, 96, 111, and 174 minutes, respectively) was observed with increasing dosages. Recovery rates for the first twitch response of the train-of-four stimulus from 10% to 25% were similar in all groups. There were no adverse hemodynamic effects secondary to large doses of vecuronium.     

Tizanidine in Chronic Tension-Type Headache: A placebo controlled double-blind cross-over study

The efficacy of tizanidine in chronic tension-type headache was compared with placebo in a randomized, double-blind and cross-over study in 37 women aged 20 to 59 years with a history of headache for 7 months to 30 years (median 5 years). The treatment periods were 6 weeks with an intervening 2 week wash-out period. The treatment was started with 6 mg/day divided into three doses, and the daily dose could be increased to 18 mg/day depending on the treatment response. The effect of the treatment was measured by visual analogue scale, verbal rating scale, number of days free of headache, number of analgesics needed, and the dose of trial medication needed. In all these measurements, tizanidine was statistically significantly more effective than placebo. The pre-trial Beck Depression Inventory score did not predict the response to treatment, neither did the level of electromyographic activity of the trapezius muscle. Side-effects, drowsiness and dry mouth were significantly more common during tizanidine treatment but they were usually mild. The results of the present trial suggest that tizanidine is effective in the treatment of chronic tension-type headache in women.     

Sutureless “button and hole” splenopexy

A new technique for fixation of a mobile spleen is described. It offers the advantages of a minimally risky procedure that very effectively keeps a mobile spleen in its bed without foreign materials and is feasible even when the gastrosplenic ligament is absent and the splenic vessels are uncovered. Our “button and hole” sutureless splenopexy was performed in six patients from 1979 to 1995. Three had a gastric volvulus (GV) and an extremely mobile spleen; one of these also had a diaphragmatic eventration. Another three had torsion of the spleen; in one it occurred 9 months after repair of a diaphragmatic hernia. We achieved good results with splenopexy as the sole operation in two cases where a wandering spleen produced a GV. Accepted: 11 February 1997     

Disturbed GABAergic transmission in mutant Han-Wistar rats: Further evidence for basal ganglia dysfunction

A mutant strain of Wistar rats which carries an autosomal gene defect is characterized by a progressively developing hyperexcitability, tremor, olfactory and gustatory movements, bradykinesia, ataxia and a pathologically increased muscle tone of hindlimbs which can be measured by recording tonic activity in the electromyogram (EMG) of the gastrocnemius-soleus muscle. The activity of the GABA synthesizing enzyme glutamic acid decarboxylase (GAD) and the receptor binding of GABA as estimated by [3H]GABA binding to synaptic membranes were examined in olfactory bulbs, frontal cerebral cortex, corpus striatum, hippocampus, thalamus, hypothalamus, tectum, substantia nigra, medulla oblongata, cerebellum, and pons of mutant rats. Mutant rats exhibit a lower activity of GAD in synaptosomal fractions of olfactory bulbs and substantia nigra whereas GAD activity within the pons was increased. The changes in the activity of GAD were accompanied by alterations in [3H]GABA binding to synaptic membranes: GABA binding was significantly elevated in the olfactory bulbs and the substantia nigra, but it was markedly reduced in the pons. The functional importance of impaired nigral GABAergic transmission in mutant rats was demonstrated by the fact that intranigral injection of the GABA agonist muscimol reduced the tonic extension of the hindlimbs as indicated by reduced tonic EMG activity of the gastrocnemius-soleus muscle, while intranigral injection of the GABA antagonist bicuculline increased the disturbance.     

肌电图对腰椎间盘突出症手术前后检测结果分析

目的:根据腰椎间盘突出症患者手术前后的肌电图表现,了解肌电图定位与手术相符合程度及手术前后神经根压迫程度的变化。方法:使用日本充电MEB—5404K型肌电一诱发电位仪对34例腰椎间盘突出症患者进行手术前后肌电图检查。结果:术前肌电图检查提示的神经根受损部位与手术中所见相符率为94.1％。术后肌电图显示神经根受压程度明显减轻。结论:肌电图对腰椎间盘突出症的神经根受压有定位价值及对术后效果有一定的评价作用。     

Sex differences in the phenotypic expression of avian dystrophy

Although the gene for muscular dystrophy in chickens is not sex-linked, results from clinical tests suggest that it is expressed differently in males and females. As measurement of muscle contractile responses provides a quantitative index for the severity of the disease, the contractile properties of the extensor digitorum communis muscle were examined in normal and dystrophic chickens with respect to sex. Furthermore, these differences were examined in young (6 to 9 weeks) and old (greater than 6 months) chickens. Results showed that age-related sex differences were apparent for those mechanical parameters of the muscle (in particular the posttetanic potentiation and posttetanic contracture) known to distinguish normal and dystrophic birds. The sex differences observed in the younger group indicate that the female birds were more severely affected by the disease than were the male. In the older group, the male were affected by the disease more severely than age-matched female birds. If the inheritance pattern is truly autosomal then it is likely that one or more developmental factors interact with the dystrophic genotype and alter the dystrophic phenotype.     

Basal ganglia: Motor influences mediated by sensory interactions

Striatopallidal lesions in rats cause an increase in trigeminal motor nucleus excitability. This hyperexcitability is not due to disruption of basal ganglia-mediated inhibition of the motor nucleus. Rather, basal ganglia lesions disrupt an inhibitory influence upon either the sensory pathway or the link-up between the sensory pathway and the motor nucleus. These data suggest that one way in which the basal ganglia influence movement is by gating sensory influences into motor areas.     

Excitation frequency and muscle fatigue: electrical responses during human voluntary and stimulated contractions.

Changes in the electrical activity of the human adductor pollicis muscle during fatiguing maximal voluntary contractions (MVCs) were compared to those resulting from equal periods of maximal ulnar nerve stimulation at different frequencies. In each case the force and smoothed, rectified EMG (SRE) were monitored continuously, and the area of the evoked surface action potential (SAP) was measured at intervals. During high-frequency stimulation (50 and 80 Hz), both the SRE and SAP area increased in the first 10 to 20 s, thereafter declining to very low values. With low-frequency stimulation (20 Hz), both increased gradually throughout the contraction. The increases in SAP area were related to a slowing of conduction velocity. In all experiments in which the frequency of stimulation was constant, changes in the SRE and SAP area mirrored one another. In sustained MVCs, the rate of force loss was less than during high-frequency stimulation. SAPs evoked by periodic single maximal shocks to the nerve increased initially in area but then remained relatively constant. The SRE no longer paralleled the SAP; it generally increased initially, but then declined roughly in proportion to the force. When the nerve was maximally stimulated at a progressively reduced frequency (80 to 20 Hz), force loss and SAP area were similar to those recorded during an MVC. The SRE was also similar in form. It is concluded that (a) during continuous high-frequency stimulation, much of the fatigue is due to failure of electrical propagation, probably largely at the muscle fiber membrane; and (b) in voluntary contractions where no similar failure was observed, muscle fatigue is minimized by a progressive reduction in motor unit activation.     

A regional histochemical and electromyographic analysis of the cat respiratory diaphragm

We analyzed the fiber type composition and pattern of electromyogram (EMG) activity in selected regions of the cat diaphragm. The muscles were composed of three basic fiber types. The percentages of each type varied markedly between and within the different regions. The muscle bordering the esophageal hiatus was highest in slow-twitch oxidative (SO) fibers, which appeared specialized to constrict the esophagus and help prevent gastroesophageal reflux. The hiatal muscle was also unique because it received bilateral phrenic motor innervation. Fiber type composition and EMG activity patterns correlated in a consistent manner, i.e., the areas highest in SO fibers yielded patterns of activity characteristic of low-threshold, tonic motor units and the regions lowest in SO and highest in fast glycolytic fibers generated patterns of activity distinctive of high-threshold, phasic motor units. All areas were electrically silent during expiration. Thus, our findings further substantiate the striking nonhomogeneous composition of the diaphragm and indicate that this heterogeneity is a consequence of regional specialization of function.