求和自回归滑动平均模型结合圆分布法分析脑卒中死亡率动态规律

通过1999年1月至2006年12月天津市脑卒中逐月死亡率数据,应用圆分布法探讨脑卒中死亡率的季节分布,动态变化规律,建立监测与预测的时间序列模型.通过模型辨识、参数估计及其检验、白噪声检验、模型的拟合度分析等过程,建立求和自回归滑动平均模型(ARIMA)的季节乘积模型(P,d,q)(P,D,Q)s.脑卒中死亡率以年为周期,一年中1月为高发月份.建立ARIMA(0,1,0)×(0,1,1)12:模型:(1-B)(1-B12)lnx1=0.001+(1-0.537B12)εt.结论:ARIMA乘积模型结合圆分布法是对脑卒中死亡率进行时间序列分析的重要方法;应用该方法可对脑卒中流行趋势及死亡率进行预测,为卫生资源合理分配、公共卫生政策计划制定和防治结果考核提供科学依据.     

利用圆形分布的统计方法分析急性脑梗死患者死亡时间昼夜节律特点

目的 回顾性分析64例急性脑梗死患者的死亡时间，探讨脑梗死患者死亡时间的昼夜节律变化的特点和规律，方法 分析64例死亡病例的临床资料，重点分析死亡时间，利用圆形分布的统计方法，计算出死亡高峰时刻和1天24小时内95％的死亡时间集中时段。结果 急性脑梗死患者的死亡高峰时刻为05：59：31，1天24小时内95％的死亡时间发生在01：04：23-10：54：39．结论 急性脑梗死患者的死亡时间有一定的昼夜节律分布的特点，清晨通常为死亡的高峰时段，与机体血栓性病理状态恶化或血压的昼夜波动有关，工作中应注意加强夜间和凌晨患者的管理和监测，必要时改变投药时间，最大限度地减少死亡率。     

The action of(±)-MDMA on medial prefrontal cortical neurons is mediated through the serotonergic system

The mechanism of action of systemitically administered(±)-MDMA (3, 4-methylenedioxymethamphetamine) on spontaneously active neurons in the medial prefrontal cortex (mPFc) of chloral hydrate anesthetized rats was examined using standard single unit extracellular recording techniques. Intravenously administered MDMA dose-dependently decreased the firing rates of the majority of mPFc neurons in control rats. In contrast, in rats that were pretreated withp-chlorophenylalanine (PCPA), which depletes the brain serotonin (5-hydroxytryptamine, 5-HT) content by inhibiting tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of 5-HT, MDMA was largely ineffective in inhibiting the firing of mPFc cells. In PCPA-treated animals, the administration of 5-hydroxytryptophan (5-HTP), which presumably restored the brain 5-HT content, but notl-DOPA, reinstated MDMA's inhibitory action in PCPA-treated rats. In rats that were pretreated withα-methyl-p-tyrosine (AMPT), which depletes the brain dopamine (DA) content by inhibiting tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of DA, MDMA inhibited the firing of all of the mPFc cells. MDMA's effect on mPFc neurons was reversed by 5-HT receptor antagonists such as granisetron and metergoline. These results strongly suggest that MDMA exerts its action on mPFc cells indirectly by releasing endogenous 5-HT.     

Light exposure required for optimum conversion of light activated resin systems

OBJECTIVE: The aim of this study was to evaluate the relationship between the degree of conversion (DC) of composites and the light intensity using LED-curing units and also to determine the amount of exposure required to achieve optimal curing. METHOD: The light outputs of light-curing units and the depths of cure of composites exposed to these units were determined using the methods outlined in modified ISO standards, ISO/TS10650 and ISO 4049, respectively. The distributions of DC in composites were investigated by IR spectra of microareas obtained at various depths from the irradiated surface of thin specimens cut out from the cured composites. IR spectra were measured using a Fourier transform infrared spectrometer equipped with a microscopic unit. DC was calculated from the changes in the amount of C=C double bonds in the IR spectra. RESULTS: The light intensity at various depths through the cured composite was calculated from the attenuation coefficient of each material, obtained from the linear relationship between the depth of cure and the logarithm of the amount of exposure, which is defined as the product of the irradiance and irradiation time. There was a third or fourth order regression relationship between DC and the logarithm of total light energy at a particular depth. SIGNIFICANCE: The minimum light energy required to produce a saturated DC was about 1000 s mW/cm2.     

Directional tuning of motion-sensitive cells in the anterior superior temporal polysensory area of the macaque

An investigation was made into the directional sensitivity of cells in the macaque anterior superior temporal polysensory region (STPa) to the motion of objects. The cells studied were sensitive to the presence of motion but showed little or no selectivity for the form of the stimulus. Directional tuning was not continuously distributed about all possible directions. The majority of cells were most responsive to motion in a direction within 15° of one of the three cartesian axes (up/down, left/right, towards/away). Tuning to direction varied in sharpness. For most (34/37) cells the angular change in direction required to reduce response to half maximal was between 45 and 70° (for 3/37 cells it was > 90°). The estimates of the directionality (median I _d = 0.97) of STPa cells was similar to that reported for posterior motion processing areas (the middle temporal area, MT, and the medial superior temporal area, MST). The tuning for direction (sharpness, distribution and discrimination) of the motion-sensitive STPa cells were found to be similar to the tuning for perspective view of STPa cells selective for static form of the head and body. On average the STPa responses showed a 100- to 300-ms transient burst of activity followed by a tonic discharge maintained at approximately 20% of the peak firing rate for the duration of stimulation. The responses of motion-sensitive STPa cells occurred at an earlier latency (mean 91 ms) than responses of cells selective for static form (mean 119 ms), but the time course of responses of the two classes of cell were similar in many other respects. The early response latency and directional selectivity indicate that motion sensitivity in STPa cells derives from the dorsal visual pathway via MT/MST. The similarity of tuning for direction and perspective view within STPa may facilitate the integration of motion and form processing within this high-level brain area.     

贫血患者血清红细胞生成素浓度的测定及临床意义

用小鼠胎肝细胞体外血浆凝块培养红系集落(Erythroid colong formig unit inculturc,E-CFUc)方法,以红细胞生成素(Erythropoietin,EPO)850323为标准试剂,测定正常人、贫血病人血清EPO浓度。实验用妊娠13～15d小鼠胎肝细胞。血清均经透析处理,培养液中加量最大不超过10％。EPO(850323)在培养液中浓度为2.5～100mU/ml。血清EPO(mU/ml)测定结果:28例正常人为48.O±17.7,12例再生障碍性贫血病人为946～>10000,1例巨幼细胞性贫血病人为500,1例缺铁性贫血病人为400和18例慢性肾功能衰竭病人则为94.2±87.6。结果表明:贫血病因对血清EPO浓度有影响。     

MELAS presenting as migraine complicated by stroke: case report

A case of MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) which presented as migraine complicated by stroke is reported. Strokes associated with migraine have often been reported, but the mechanism remains unclear and may include a variety of pathologies. MELAS also presents with migrainous headache, vomiting, and stroke-like symptoms. Magnetic resonance imaging demonstrates characteristic findings. MELAS should be considered in the differential diagnosis of infarct-like lesions with migrainous headaches in young adults, especially if the symptoms fluctuate and are accompanied by a homonymous hemianopia. Received: 23 September 1996 Accepted: 19 February 1997     

THE CONTROL OF HUMAN MOTOR UNITS

1. The motor unit, consisting of a single motor neuron and the skeletal muscle fibres that it innervates, is the final output pathway of the motor system. 2. Much is now known about the way that human motor neurons are recruited and controlled during voluntary and reflex movements. This review briefly summarizes some of the recent experimental data that has contributed to our present understanding. The review is largely limited to data obtained in human experiments. While much of what we know about the organization of the nervous system has come from studies of the anatomy and physiology of experimental animals, there are some questions that cannot be addressed in reduced animal preparations. The development of new techniques has made it possible to investigate the human nervous system at a level of detail that has not hitherto been possible.     

Interleukin-2, its soluble receptor,and soluble T8 antigen in acute ischemic stroke

The treatment of neoplasia with interleukin-2 (IL-2) can be complicated by neurological deficits resembling transient Ischemic attack and stroke. We investigated whether interleukin-2 contributes to the natural course of cerebrovascular ischemia and particularly to the pathogenesis of infection-associated stroke. Plasma levels of interleukin-2 were below the level of detectability in almost all measurements. Patients with and without previous infection (n = 11, 805 ±445 U/ml vs n = 19, 824 ± 501 U/ml) did not have significantly higher levels of soluble interleukin-2 receptors than control subjects with (n = 14, 667 ± 229 U/ml) or without vascular risk factors (n = 17, 567 ± 176 U/ml). Receptor levels increased in patients during the first week after stroke (n = 15, 1157 ± 1013, p < 0.02). Levels of soluble T8 antigen (sT8) were higher in patients (n – 26, 320 ± 112 U/ml) than in healthy control subjects (n = 15, 246 ± 92 U/ml; p < 0.05) and sT8 levels increased during the first week after stroke (p < 0.05). These results reflect an immunological response to the cerebral infarct; they do not indicate a general role of the IL-2 system in the pathogenesis of ischemic stroke with or without previous infection.     

经皮扩张性气管切开术的临床应用

目的：探讨经皮扩张性气管切开术行气管切开及气道套管插入的方法与效果。方法：在内科ICU病房内，采用一步性扩张气管切开术，对35例患者进行气管切开，同时采用纤维支气管镜对其中l0例患者进行气道内检查。结果：按照操作规程，均完成了气管切开及气管套管的插入，平均操作时间为5．4min．所有患者在带管过程中及拔管后，未发现有气道狭窄的发生，无瘘管或瘘道形成，且创口愈合良好。结论：经皮扩张性气管切开术操作简便易行，值得临床推广使用。