Effect of neurotensin and epinephrine on sinus arrhythmia caused by burst stimulation of the vagus nerve

Administration of neurotensin against the background of sinus arrhythmia caused by burst stimulation of the vagus nerve in cats restores synchronization of the cardiac and vagal rhythms or modulates the proportion between them. This either stops the arrhythmia or changes its parameters. The effects of the peptide are similar to those of epinephrine and are abolished by β-adrenoreceptor blockage. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 123, No. 5, pp. 494–497, May, 1997     

经食道心房调搏测定窦房结功能

对27例病窦综合征患者和42例正常对照组,经食道心房调搏,测定窦房结功能。发现病窦患者,窦房结恢复时间>1450ms;校正窦房结恢复时间≥550ms;窦房结传异时间>191ms;固有心率均明显低于正常对照组(R<0.01)。用阿托品,心得安进行功能性植物阻滞前、后观察,发现阻滞后各次参数在正常对照组中有明显降低,而病窦组则无明显差异。实验证明,经食道心房调搏方法是无创性窦房结功能检查的有效方法。     

蝶塞及毗邻关系的解剖对蝶窦手术重要性探讨

蝶窦居于颅底，毗邻结构复杂，常有变异。本文报告开展各类型蝶窦手术１２５例，并就蝶窦区域应用解剖对蝶窦手术的重要性，进行研究与探讨。     

Frontal versus transcorneal stimulation to induce maximal electroshock seizures or kindling in mice and rats

Frontal stimulation, i.e. electrical stimulation where electrodes are pressed on the skin of the intact frontal skull of mice or rats, may represent a more humane alternative to the widely used transcorneal stimulation to induce electroshock seizures. The aim of this work was to directly compare transcorneal and frontal stimulation in eliciting maximal electroshock-induced seizures (MES) in mice and the anticonvulsant effect of carbamazepine (CBZ) and phenytoin (PHT) on thus produced seizures. In addition, we stimulated mice and rats repeatedly via transcorneal and frontal electrodes to see whether kindling is produced by this procedure. Two electroshock tests were used in mice, i.e. maximal electroshock seizure threshold (MEST) test and MES generated by supramaximal stimulation (50 mA). Frontal stimulation resulted in lower convulsive threshold than in the case of corneal stimulation. Both CBZ and PHT produced dose-dependent increases in seizure threshold for both sites of stimulation, i.e. transcorneal and frontal. As regards type of electrodes, higher doses of PHT were required to increase seizure threshold in the case of frontal than transcorneal stimulation. Supramaximal stimulation (50 mA) yielded comparable ED₅₀ values regardless of the site of stimulation. Furthermore, once-daily stimulation of mice, regardless of the placement of electrodes, did not induce any changes in convulsive threshold. We also attempted to kindle mice and rats via corneal and frontal electrodes by repetitive electrical stimulation using currents which initially did not produce generalized clonic seizures. Mice were stimulated once daily for 2 s with 3 mA (corneal electrodes) or 2 mA (frontal electrodes) and rats were stimulated twice daily for 4 s at 8 mA (corneal electrodes) or 5 mA (frontal electrodes). With corneal stimulation in rats there was a clear progression of kindling development which was not the same in nature when compared with corneally-stimulated mice. Frontal stimulation did not produce kindling. Moreover, corneal stimulation was better tolerated by rats, while in mice high mortality was seen after either method of current delivery. Our data indicate that frontal electrodes can be used as an alternative to transcorneal stimulation to produce MES by supramaximal or threshold current intensities as screening procedures in antiepileptic drug (AED) development. Nevertheless, this type of stimulation cannot be used to produce minimal electroshock seizures and seems not to be useful to produce kindling in rats and mice.     

脑静脉血栓病人的死亡因素分析(附5例分析)

目的分析脑静脉血栓(CVT)病人的死亡原因。方法回顾分析136例CVT病人中5例死亡病例的病因、临床表现、影像学资料、治疗经过及死亡原因。结果病死率为3.7%。2例在急性期死亡,3例在慢性期死亡。直接死亡因素均为脑疝;间接死亡因素为颅内多发性出血和多个部位的脑静脉血栓形成,死亡组(3.20±0.84)支静脉受累,存活组(2.09±1.00)支静脉受累(P=0.016)。而性别、年龄、确诊时间、癫疒间发作、病灶部位及治疗前颅内压等没有显著增加死亡的危险性。某些临床表现,如失语、运动障碍、精神症状及意识障碍与死亡有关,但其系多发性颅内出血及多个部位脑静脉血栓所致。结论CVT病人的直接死亡原因为脑疝,间接原因为多发性脑静脉血栓和颅内多发性出血。死亡不仅可以发生在急性期,也可以出现在慢性期。     

Sinoatrial Node Electrogram Studies in Patients with Sick Sinus Syndrome

Sinoatrial node electrogram (SNE) was recorded successfully in recent years, using transvenous electrode catheter. Via SNE and intratrialelectrogram (IEG), one could measure sinoatrial conduction time(SACT) directly, observe sinoatrial node (SN) potential changes in cadiac cycles, diagnose some sinus arrhythmias which couldn't be confirmed by surface ECG. All these could offer accurate evidence for differential diagnosis of sick sinus syndrome (SSS). The authors recommend a modified method for the location of the electrode catheter, by which one can increase success rate of obtaining stable SNE. Using this method, the authors recorded SNE in 10 cases with SSS successfully.     

三种去神经法对清醒大鼠动脉压力感受性反射功能的影响

目的：测定急、慢性去主动脉神经（ＡＤ）、去颈动脉窦神经（ＳＤ）、同时去主动脉和窦神经（ＳＡＤ）后大鼠动脉压力感受性反射对血压控制（ＡＢＲ－ＢＰ）和心动周期控制（ＡＢＲ－ＨＰ）的影响。方法：测定ＡＢＲ－ＢＰ采用阻断动脉压力感受性反射传出通路前后，比较机体对去氧肾上腺素升压反应面积差异的方法，所得数值与改良的Ｓｍｙｔｈ方法测定的ＡＢＲ－ＨＰ值进行比较。结果：（１）大鼠ＳＡＤ后ＡＢＲ－ＨＰ为零，且代偿不明显；而ＡＢＲ－ＢＰ约为３０％，且代偿明显；（２）ＳＤ后ＡＢＲ－ＢＰ与ＡＢＲ－ＨＰ无显著差异，而ＡＤ和ＳＡＤ后ＡＢＲ－ＢＰ的作用显著大于ＡＢＲ－ＨＰ的作用。结论：（１）大鼠的ＡＢＲ－ＨＰ传入冲动全部来自于主动脉弓和颈动脉窦的压力感受器，而ＡＢＲ－ＢＰ传入冲动大部分来自于这两处的感受器；（２）主动脉神经和窦神经感受传入在ＡＢＲ－ＢＰ中的作用是相当的，并有明显的相互代偿；而在ＡＢＲ－ＨＰ中，主动脉神经的作用比窦神经重要，其代偿能力也比窦神经显著。     

The discriminative stimulus effects of ethanol are mediated by NMDA and GABAA receptors in specific limbic brain regions

 This study was conducted to assess the involvement of N-methyl-d-aspartate (NMDA) and γ-aminobutyric acid (GABA) receptor systems, located in specific limbic brain regions, in the discriminative stimulus effects of ethanol. Male Long-Evans rats were trained to discriminate between intraperitoneal (IP) injections of ethanol (1 g/kg) and saline on a two-lever drug discrimination task. The rats were then implanted with bilateral injector guides aimed at the nucleus accumbens core (AcbC), prelimbic cortex (PrLC), hippocampus area CA1 (CA1), or extended amygdala (i.e., at the border of the central and basolateral nuclei). Infusions of the non-competitive NMDA antagonist MK 801 in the AcbC or CA1 resulted in dose-dependent full substitution for IP ethanol. MK 801 infusion in the PrLC or amygdala failed to substitute for ethanol. Injection of the competitive NMDA antagonist CPP in the AcbC also failed to substitute for ethanol. Co-infusion of MK 801 in the hippocampus potentiated the effects of MK 801 in the AcbC, whereas NMDA infusion in the hippocampus attenuated the ability of MK 801 in the AcbC to substitute for ethanol. The direct GABA_A agonist muscimol resulted in dose-dependent full substitution for IP ethanol when it was injected into the AcbC or amygdala, but failed to substitute when administered in the PrLC. Co-infusion of MK 801, but not CPP, potentiated the effects of muscimol in the AcbC. These results demonstrate that ethanol’s discriminative stimulus function is mediated centrally by NMDA and GABA_A receptors located in specific limbic brain regions. The data also suggest that the discriminative stimulus effects of ethanol are mediated by interactions between ionotropic GABA_A and NMDA receptors in the nucleus accumbens, and by interactions among brain regions. Received: 2 December 1997 / Final version: 24 January 1998     

The influence of intravenous magnesium sulphate on the occurrence of atrial fibrillation after coronary artery by-pass operation

To examine the influence of (Mg) on hypomagnesaemia and atrialfibrillation (AF) following coronary artery by-pass surgery,140 consecutive patients were randomized to receive 70 mmolof magnesium sulphate intravenously (n = 69) or placebo (n =71). Serum magnesium concentrations fell to 0.77 ± 0.10mmol. l^–1 in the control group but rose to 1.09 ±0.17 mmol. l^–1 in the Mg group (P <0.001). The incidenceof AF was 29% in the Mg group and 26% in the placebo group (NS).The AF patients were older, more of them had had prior AF episodes,their sinus rates (SR) were slower (78 ± 10 vs 86 ±12 beats. Min^–1; P <0.01) and serum Mg concentrationshigher (0.89 ± 0.21 vs 0.11 mmol. ^l–1; P <0.05)The incidence of AF was 43% in the highest quartile of serumMg and 23% among the rest (P = 0.056). In patients experiencingAF during the first three post-operative days, serum Mg concentrationswere higher and SR slower on each day compared with non-AF patients.SR increased post-operatively less with high Mg levels (P =0.044). In the Mg group, serum Mg and SR were the only independentpredictors of AF. In conclusion, the incidence of post-operativeAF is not decreased with magnesium. High Mg levels are likelyto provoke AF probably by mechanisms that modify SR.