Effects of propafenone on calcium current in guinea-pig ventricular myocytes.

1. The modulation of L-type voltage-sensitive calcium channels in guinea-pig isolated ventricular myocytes by propafenone was examined by the whole cell voltage-clamp technique. 2. Propafenone, 10(-7) -5 x 10(-5) M, produced a concentration-dependent inhibition of Ca current (ICa) without any significant change in the current-voltage relation. Half-blocking concentration (IC50) of propafenone for the peak ICa at +10 mV was 5 x 10(-6) M. 3. The voltage-dependence of ICa inactivation was shifted in the hyperpolarizing direction in the presence of 5 x 10(-6) M propafenone. 4. A frequency-dependent relative block by propafenone was observed after repetitive depolarizing test pulses at a frequency of 0.5 and 1 Hz. The recovery of ICa from inactivation was prolonged by propafenone and the reactivation exhibited an additional exponential component attributed to the slow release from drug block of Ca channels. 5. These results suggest that propafenone, at therapeutic concentrations exhibits Ca channel blocking properties that may be involved in its antiarrhythmic mechanism.     

荧光原位杂交技术分析人结肠菌群方法研究

建立荧光原位杂交技术分析人体内结肠菌群的方法。取受试者新鲜粪便 ,选用 5种特异性的 16SrRNA寡核苷酸探针 ,检测粪便样本收集后的保存时间、温度 ,离心条件及样本固定液存放时间对杂交计数结果的影响。结果建立最佳实验条件为 :粪便样本收集后应尽快在 4℃下保存 ,放置时间不要超过 12小时即作处理 ;样本的适宜离心条件为 70 0g 2分钟 ;样本用多聚甲醛固定后在 - 80℃下存放时间不要超过 5个月。该方法具有较好的稳定性 ,可以有效地检出个体之间结肠菌群的差异。     

Effects of the two enantiomers, S-16257-2 and S-16260-2, of a new bradycardic agent on guinea-pig isolated cardiac preparations.

1. The electromechanical effects of two enantiomers, S-16257-2 (S57) and S-16260-2 (R60), were studied and compared in guinea-pig isolated atria and ventricular papillary muscles. The possible stereoselectivity of the interaction on the cardiac Na+ channel was analysed by comparing the effects of the two enantiomers on the onset and recovery kinetics of the frequency-dependent Vmax block. 2. In spontaneously beating right atria, S57 and R60 (10(-8)M-10(-4M) exerted a negative chronotropic effect (pIC50 = 5.07 +/- 0.19 and 4.76 +/- 0.18, respectively) and prolonged the sinus node recovery time, this effect being more marked with S57. In electrically driven left atria, S57 decreased (P < 0.05) contractile force only at 10(-4M) and R60 at concentrations > or = 5 x 10(-5M), whereas in papillary muscles the negative inotropic effect appeared at concentrations > 10(-5M). 3. In papillary muscles driven at 1 Hz, S57 and R60 at concentrations higher than 5 x 10(-6M) produced a concentration-dependent decrease in the maximum upstroke velocity (Vmax) and amplitude of the cardiac action potential without altering the resting membrane potential or the action potential duration. S57 and R60 had no effect on the characteristics of the slow action potentials elicited by isoprenaline in ventricular muscle fibres depolarized in high K+ (27 mM) solution. 4. At 5 x 10(-5M), S57 and R60 produced a small tonic Vmax block. However, in muscles driven at rates between 0.5 and 3 Hz both enantiomers produced an exponential decline in Vmax (frequency-dependent Vmax block) which augmented at higher rates of stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Extended pericranial flap and bone graft reconstruction in anterior skull base surgery.

OBJECTIVES: The objectives of this study was to establish a rationale for repairing large anterior skull base defects with an extended pericranial flap and split calvarial bone graft; to define large anterior skull base defects as those spanning the anterior cranial measuring at least 3.0 x 4.0 cm; and to describe the surgical technique and compare it with alternative strategies.Study design Thirty-four patients underwent anterior craniofacial resection of anterior skull-based tumors of varying histology with reconstruction using an extended pericranial flap and split calvarial bone graft. RESULTS: The survival of the pericranial flap and bone graft was maintained in 33 of 34 patients. There was 1 episode of postoperative cerebrospinal fluid leak, 1 episode of osteomyelitis of the bone graft and an epidural abscess, and 1 episode of asymptomatic pneumocephalus. CONCLUSION: Split calvarial bone graft with an extended pericranial flap is an effective technique for reconstructing large anterior skull base defects.