Arterial baroreflex influence on heart rate variability: A mathematical model-based analysis

The influence of the arterial baroreflex on the heart rate variability is analysed by using a mathematical model of heart rate baroreceptor control. The basic mechanisms of the model, sufficient to elicit heart rate variability include: systemic circulation, a non-pulsatile cardiac pump and nonlinear negative feedback simulating arterial baroreflex closed-loop control of the heart rate (−3bpm/mmHg as maximum reflex sensitivity). The latter reproduces, through two distinct delayed branches (0.8 and 2.8 s), the short-term autonomic control effected respectively by sympathetic and parasympathetic divisions on the sinus node. By means of this model, two distinct self-sustained oscillatory components with incommensurate frequencies (0.1 and 0.26 Hz) are reproduced. Frequencies of these two oscillatory components closely agree with the main heart rate rhythms in humans (0.09±0.01 Hz and 0.26±0.01 Hz). When sympathetic-mediated regulation prevails over parasympathetic activity, simulated heart rate oscillation is characterised by a low frequency (∼0.1 Hz). On the other hand, a high-frequency oscillatory component (∼0.26 Hz) appears when enhanced vagal activation or partial inhibition of the sympathetic control is simulated. When both autonomic divisions are operative, both low- and high-frequency components are present and the heart rate oscillates quasi-periodically. This variability in heart rate at different frequencies is reproduced without including outside perturbations and is due to the nonlinear delayed structure of the closed-loop control. Bifurcation theory of nonlinear system is used to explain the high sensitivity of the heart rate oscillatory pattern to model parameter changes.     

Fibroblast growth factor-2 is selectively modulated in the rat brain by E-5842, a preferential sigma-1 receptor ligand and putative atypical antipsychotic

Fibroblast growth factor-2 (FGF-2) is a member of a large family of trophic factors whose expression is regulated under several conditions in different areas of the brain. The goal of our experiments was to determine whether the administration of 4-(4-fluorophenyl)-1,2,3,6-tetrahydro-1-[4-(1,2,4-triazol-1-il)butyl] pyridine citrate (E-5842), a sigma-1 receptor ligand and putative atypical antipsychotic, could regulate the expression of FGF-2. After chronic treatment with E-5842 (21 days, and the animals killed 24 h after the last administration), an up-regulation was observed of the expression of FGF-2 mRNA in the prefrontal cortex and the striatum, and a down-regulation of the expression of FGF-2 mRNA in the hypothalamus of the rat brain. Acute treatment with E-5842 (one single administration and animals killed 6 h later) up-regulated FGF-2 expression in the prefrontal cortex, the striatum, the hypothalamus and the hippocampus in a dose-dependent manner. The acute up-regulation was transient and disappeared 24 h after E-5842 administration. The induction of FGF-2 in the striatum after repeated administration has been described for clozapine, but our data concerning regulation in the prefrontal cortex suggest that this effect is unique to E-5852 among other antipsychotics. Given the neuroprotective activity of FGF-2, the data presented here might be relevant to the deficit in cognition and other symptoms that appear in schizophrenia.     

不同构建策略对D-氨基酸氧化酶表达的影响及发酵调节

目的 构建不含编码β-内酰胺酶编码基因的D-氨基酸氧化酶(D-amino acid oxidase,DAAO)工程菌,对不同构建策略构建的重组菌进行发酵调节研究.方法 采用分子生物学手段,利用不同的策略、不同的毕赤酵母宿主菌,构建DAAO工程菌;利用微生物发酵和调节手段,对工程菌的发酵条件进行优化.结果 获得了表型不同的3株重组菌(Muts的PDK13和PDGA10,Mut 的PDG27),它们的最佳生长条件基本相似,诱导表达条件却不相同,在Basal salts培养基内,当生长时间为36 h,诱导培养基起始pH为6.0、甲醇浓度为0.5%时,最有利于DAAO表达.在菌体密度相同的条件下,Mut 表型(PDG27)甲醇代谢快,诱导24 h,DAAO活力达到最高;Muts型(PDK13和PDGA10)甲醇代谢慢,诱导36 h,DAAO活力达最高;通气量一定时,菌体密度增加,DAAO表达量增加,菌体增加到一定程度表达量反而下降,表明通气量应随菌体密度的增大而增加.结论 Muts型重组菌对通气量要求低且更有利于高密度发酵.     

对某基层医疗机构药事管理混乱引发问题的思考

对某基层医疗机构在药事管理工作中存在的违规问题及其原因进行分析,提出了应加大药事管理工作的监管力度,规范基层医疗机构药事管理工作行为的建议。     

Translational Regulation as a Novel Mechanism for the Development of Cellular Drug Resistance

Cellular drug resistance is one of the principal obstacles to the clinical efficacy of cancer chemotherapy. In this review, we describe the potential role for translational regulation as a novel mechanism for modulating chemosensitivity. The evidence for the translational control of thymidylate synthase, dihydrofolate reductase, and p53 will be presented, as will experimental data showing how disruptions in this important regulatory process can lead to the rapid emergence of cellular drug resistance.     

情绪调节量表的信度和效度研究

目的考察情绪调节量表的信度和效度。方法采用新近编制的情绪调节量表对5个样本共1163名大学生被试进行了测试。结果情绪调节量表具有良好的信度指标,重新评价和表达抑制维度的重测信度系数分别是0.85和0.87;5个样本和总样本两个维度的α系数和G系数均达到了0.76以上。验证性因素分析的结果显示两因子相关为自由估计的标准测量模型与实际数据的拟合程度良好（2为364.21,2/DF为4.79,NFI为0.96,NNFI为0.96,IFI为0.97,CFI为0.97,RMSEA为0.057）,两因子相关为0的独立模型与标准测量模型之间无显著差异。效标效度的研究显示5个样本和总样本两个维度的效标指数均达到了0.70以上。实证效度的研究发现男性被试在表达抑制维度上的得分要显著高于女性被试。结论情绪调节量表具有良好的心理测量学品质,值得进一步推广和应用。     

空腹血糖受损人群血液流变学变化特点及临床意义

目的探讨空腹血糖受损人群血液流变学特性及临床意义。方法分别检测正常糖耐量对照者（NGT组）、空腹血糖受损者（IFG组）和糖尿病者（DM组）的血糖，血脂和血液流变学等指标。结果IFG组和DM组的血糖（GLU）、总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白胆固醇（LDL-C）、全血高切粘度（ηbH）、全血中切粘度（ηbM）、全血低切粘度（ηpL）、红细胞压积（HCT）、红细胞刚性指数（ERI）、红细胞聚集指数（EAI）、红细胞变形指数（TK）显著高于NGT组（P〈0．01），高密度脂蛋白胆回醇（HDL-C）显著低于NGT组（P〈0，01）；DM组的GLU、TG、ERI显著高于IFG组（P〈0，01），HDL-C显著低于IFG组（P〈0．01）。三组的血浆粘度差异无统计学意义（P〉0．05）。结论不仅DM者存在高粘血症．在IFG阶段就已经存在明显血液流变学的改变．血液流变学改变可能参与了糖尿病及其并发症的发生及发展。     

医患和谐需要"双向道德规范"

医患关系的特殊性,决定了协调医患关系需要双向道德规范。而对这一问题的探讨,不仅引发了人们思考特殊领域里人际伦理关系协调的双向性特点。而且也从一般意义上凸显了当前双向伦理规范研究的必要性和迫切性。