漫反射光谱法研究维生素C与片剂辅料的相互作用

漫反射是一束光射到一定厚度的不透明不光滑固体表面上,光被部分吸收和部分散射后,向各个方向的反射。反射光的分数称为反射率。测定反射率时一般与某种白色粉末(例如硫酸钡)相比较,测得的反射率为相对反射率。以相对反射率对波长作图所得的曲线称为漫反射光     

Blood flow imaging with MR: spin-phase phenomena

Blood flow phenomena occurring when flow is within the magnetic resonance (MR) imaging plane were analyzed. In this situation, the signal intensity of vascular lumina is predominantly determined by spin-phase change phenomena, and section transition effects of moving spins can be neglected. In this paper, we develop the concepts of in-plane flow, with emphasis on the notion that the spatial variations in velocity and acceleration of blood, which mainly occur along vessel walls, are important determinants of intravascular signal loss in MR images. Flow patterns in the large mediastinal arteries were qualitatively and quantitatively analyzed in six healthy subjects and 14 patients with hemodynamic abnormalities using multiple electrocardiograph-gated image acquisition; ungated studies of 30 patients were analyzed for venous flow effects. Intraluminal signal was strongly dependent on the phase of the cardiac cycle and the echo number. Signal loss was found to occur along vessel walls, in vascular bends, and at bifurcations.     

维生素K3粉末降解动力学

在温度为50～90℃,相对湿度为50～93%范围内,维生素K₃的变色速率方程为—dR/dt=k_RR,降解速率方程为d(C_o—c)/dt=k_C(c_o—c)^1/2,光解速率方程为—dR/dt=k_P(R_o—R)^-1。k_R和_C与热力学温度T和相对湿度RH的关系通式为k=k′exp(—E_A/RT)exp(m′RH)。在实验温度和湿度范围内,变色和降解的表观活化能平均值分别为105.51和130.72 kJ/mol。     

指数程序升温药物稳定性试验

介绍了一种新的程序升温(指数程序升温)药物稳定性预测加速试验方法及计算方法。在这一新的程序升温方法中,温度每升高10℃,升温速率将增大2～4倍:dT/dt=a^(T-T₀)/10·(dT/dt)₀,使药物在高温和低温范围内的降解程度尽可能一致,提高了试验准确度。采用单因素优选法和数值积分法处理试验数据,避免了任何近似处理,使计算结果准确可靠。与线性升温、倒数升温和对数升温加速试验进行了对比,结果表明,指数程序升温法的准确性优于其它3种升温法。     

A study of twins--in search of an optimal age for delivery

The question regarding the optimal age of delivery in twins remains unanswered. A prospective observational study was carried out in the gynaecology and obstetrics department of RG Kar Medical College and Hospital, Kolkata during 2008-2009 to arrive at a logical conclusion to this question. The objective of this study was to evaluate the optimal timing of delivery in twins and compare the perinatal outcome in these babies by dividing them into 3 groups: 34 weeks to 35 weeks 6 days, 36 weeks to 37 weeks 6 days and >38 weeks. Perinatal outcome was also compared between different modes of delivery. Few maternal complications like pre-eclampsia, anaemia, premature rupture of membrane, preterm labour and antepartum haemorrhage were also evaluated.     

Mitochondrial oxidative stress and permeability transition in isoniazid and rifampicin induced liver injury in mice

BACKGROUND/AIMS: To evaluate the role of mitochondrial oxidative stress and permeability transition (MPT) in isoniazid (INH) and rifampicin (RMP) induced hepatotoxicity in mice. METHODS: Liver damage was induced by co-treatment of INH (50 mg/kg) and RMP (100 mg/kg). Pre-treatment with either methionine or phorone was done to modulate hepatic GSH level. Liver cell injury was assessed biochemically and histologically.Evidence of apoptosis was sought by TUNEL test, caspase assay and histology. RESULTS: INH and RMP co-treatment caused steatosis and increased apoptosis of the hepatocytes, hepatic oxidative stress, particularly in the mitochondrial fraction with increased mitochondrial permeability transition (MPT).Mitochondrial oxidative stress as well as liver cell injury was increased by prior treatment with phorone. This was attenuated by pretreatment with methionine suggesting a glutathione (GSH) dependent phenomenon. CONCLUSIONS: Oxidative stress in the mitochondria and inappropriate MPT are important in the pathogenesis of apoptotic liver cell injury in INH-RMP hepatotoxicity. The phenomenon is GSH dependent and methionine supplementation might have a protective role.