Simulation of laser tomoscopy in a heterogeneous biological medium

A Monte Carlo model has been developed to study the propagation of an ultrashort light pulse through a heterogeneous thick biological specimen. A circular blood vessel is moved within a tissular slab to simulate biological specimen scanning using a picosecond laser source and a collimated ultrafast multichannel opticl shutter. Features of the transmitted light are computed for each position of the blood vessel. The computer program gives an account of the transmitted photons, the flight time which does not exceed straightforward crossing time plus time gate of known duration. A small blood vessel (radius R=2 mm) placed in a 40 mm thick slab is easily located when a time gate of 10 ps duration is employed. Such a time gate also allows the detection of a middle-sized vessel (R=4 mm) embedded in a thicker sample (80 mm). The contrast computed for the transmittance profile is greatly improved when a time gate is used. In addition, shifting of the blood vessel towards the unilluminated side of the sample decreases the contrast. We demonstrate that the time selection process may provide a substantial improvement to the laser tomoscopy technique when used for imaging biological media.     

Laser tomography of heterogeneous scattering media using spatial and temporal resolution

Time-resolved tomography is performed in transillumination by using 527 nm picosecond pulses from a passively mode-locked doubled Nd/glass laser and a streak camera to select photons according to their flight time. This work reports on the increase in contrast of a time-resolved profile of a 2 mm radius opaque object embedded in a scattering medium, constituted of diluted milk in a 30 mm thick cell. For spatial analysis, the emerging photons are detected through a 6 mm slit at the outlet face of the cell. Transmission profiles obtained as a function of time show that the contrast is enhanced for the shortest flight times, while the ‘shadow’ of the object is no longer detected after about 100 ps. Moreover, improvements in contrast are studied for different configurations of the model, to analyse separately the role of collimated and scattered photons. It is expected that such a tomographic method based on time-resolved absorption could be applied to imaging for more complex biological structures in the red and near-infra-red range.     

局限性癫痫脑电时间序列的分形维数计算比较

为探索应用非线性动力学理论诊断癫痫病的新方法，对局限性癫痫病患者脑电时间序列进行了相关维数（Ｄｃ）和波形维数（Ｄｗ）的计算比较。观察到，痫性导联脑电的分形维数多低于对侧导联的值；相关维数Ｄｃ的相对变化量较波形维数Ｄｗ大；而波形维数Ｄｗ对痫性棘波敏感；结果提示，脑电时间序列的分形维数有可能成为诊断癫痫的特征参数，值得进一步深入研究。     

Interaction of a Motor Response, and Reaction Time and Time Estimation Tasks, on Heart Rate and Skin Conductance

The influence of motor responding and typical psychophysiological tasks on heart rate was tested by manipulating motor requirements of reaction time (RT) and time estimation (TE) tasks. Thirty-four volunteers were assigned randomly to four groups. Two groups squeezed a hand dynamometer at the start of a trial and the other two groups squeezed at the finish of the trial. The force of the squeeze was also manipulated: either 3 kg (3) or 7 kg (7). The four groups were Start 3, Start 7, Finish 3, and Finish 7. All subjects participated in the TE and RT tasks. The dependent variables were measurements of forearm flexor muscle tension, heart rate and skin conductance. It was found that the manipulations of when and with what force a person squeezed the dynamometer resulted in reliable group differences in muscle tension. The magnitude of acceleratory components of the triphasic (acceleration-deceleration-acceleration) cardiac response was amplified by tension. The magnitude of the deceleratory component seemed to depend on both muscle tension and stimulus processing. Except for the magnitude of the response-bound deceleration, RT and TE produced very similar heart rate responses, and skin conductance did not differ among groups. The data were interpreted as providing evidence that motor response acts as an amplifier for the phasic HR produced by common psychological paradigms.     

SARS病人外周血T淋巴细胞的动态变化及其在发病进程和发病机理中的意义

目的 :通过研究严重急性呼吸综合征 (SevereAcuteRespiratorySyndrome,SARS)患者外周血免疫细胞的动态变化 ,探讨外周血免疫细胞在SARS发病进程中的意义 ,初步探讨SARS的发病机理 ,并为SARS的诊断和治疗提供有力的实验室依据。方法 :回顾性动态观察我院收治的已治愈SARS病例和SARS死亡病例外周血CD4 + 和CD8+ T淋巴细胞 ,评估外周血免疫细胞在SARS发病进程及预后中的作用。实验方法为流式细胞术检测和分析免疫细胞表面特异性荧光抗体标记 ,T细胞表面标志组合为CD3 CD8 CD4 5 CD4。结果 :所有治愈的SARS病人的CD4 + 和CD8+ T淋巴细胞都有不同程度的可逆性下降 ,而所有的死亡病例有不可逆性显著下降 ,直至死亡。T细胞下降程度和维持的时间与病情密切相关。普通型SARS病例最低CD4 + T淋巴细胞数为 30 5± 15 0cells μl(P <0 .0 0 1)、重型为 139± 6 9cells μl(P <0 .0 0 1) ,普通型SARS病例最低CD8+ T淋巴细胞数为 2 2 3± 89cells μl(P <0 .0 0 1)、重型为 171± 92cells μl(P <0 .0 0 1)。所有普通型病例和大部分重型病例T淋巴细胞恢复正常 ,个别重型病例低于正常或接近正常 ,恢复后普通型平均为 991± 2 86cells μl,重型平均为 5 4 5± 2 2 5cells μl。恢复时间有所不同 ,普通型平均为 17± 5天     

Processing of binaural stimuli by cat superior olivary complex neurons

Summary A method was developed to record stereotactically from the cat Superior Olivary Complex (SOC) using glass micropipettes. Sound stimulation was given through a closed system that permitted independent variation of interaural time (time) and intensity (int) differences. The most common binaural units found (n = 34) were ipsilateral excitatory, contralateral inhibitory (EI¹), cells of the Lateral Superior Olive (LSO). Some Medial Superior Olive (MSO) cells and presumed MSO ascending afferents were found but, as noted by other authors, we found it difficult to obtain single unit recordings from this nucleus. The LSO EI cells were mostly sensitive to higher frequencies and showed Peristimulus Time Histograms (PSTHs) consisting of a sharp On response followed by a plateau when stimulated with Best Frequency (BF) tone bursts or noise bursts. This On response was sensitive to time and int such that ipsilateral time lead or intensity increase resulted in a stronger response. The response reached a minimum around zero time or int. No sharp peaks or dips were seen in the physiological range needed for localization, instead the response increased with increasing ipsilateral lead or intensity to the maximum values tested (2048 s time, 30 dB int). In the physiological range the time and int response were complementary (both increasing response as ipsilaterality was increased). Provided enough sound energy in the unit's sensitive region was present, the same time curves were produced when BF tone bursts, masked tone bursts, sharp onset tone bursts or noise bursts were used. Changing the time of the carrier of the tone burst alone had no effect (except for one cell with a BF of 560 Hz), only the relative time of arrival of the stimulus envelope seemed to be important. In contrast to these LSO EI cells MSO-type units showed EI or EE predominantly low frequency phase-locked responses. When stimulated with interaurally phase shifted (pha) BF tones the unit response was a cyclic function of pha. Some cells (all that were tested, n = 6 including the 560 Hz LSO EI cell) showed these cyclic responses when stimulated with noise bursts or non-BF tones. However, these characteristic delays were not necessarily in the physiological range, i.e. we could find no evidence that these units were responding to time/pha values corresponding to a particular sound source direction. In both LSO and MSO it seems that integration of information higher in the CNS from a population of these cells is necessary for unambiguous coding of sound source direction. The time intensity trading ratios measured in two MSO type cells (11 and 26 /dB) were clearly different to those measured in LSO EI cells (n = 6, 99–550 s/dB). These ratios correspond approximately to those of the psychophysical time and int images measured by Hafter and Jeffress (1968).Supported by the Deutsche Forschungsgemeinschaft (SFB 45)     

Extrapelvic colon--areas of failure in a reoperation series: implications for adjuvant therapy

A total of 230 patients had planned single or multiple reoperative procedures following "curative" resection of colorectal cancer at the University of Minnesota. The site of the primary lesion was extrapelvic in 91, and later evidence of cancer was found in 58 patients (64%) at re-operation and/or other follow-up. Eight of the 58 (14%) were converted to disease-free status. Incidence and patterns of failure were correlated with initial operative-pathologic extent of disease (87 of the 91 at risk had initial tumor extension beyond the bowel wall, involved nodes or both) and comparisons were made with the previously analyzed rectal reoperation patients. While a component of local-regional failure was more common with rectal lesions (48/74 at risk, 65%), it was not uncommon with extrapelvic primaries (44/91-48%). The incidence of hematogenous metastasis (DM) was equal, but the pattern of initial DM differed (extrapelvic colon--primarily liver; rectum--liver and lung). Peritoneal seeding was a more common component of failure with the extrapelvic primaries (19/91--21% vs 3/74-4%). Since surgery alone is inadequate treatment for many patients with colon as well as rectal cancer, the rationale of adjuvant radiation and systemic therapy, alone or in combination, is discussed.     

刍议祖国医学中时间与人体的关系——34年1054例住院心脏病患者死亡时间规律探讨

本文从中医“天人相参”的基本观点出发,根据祖国医学中大量关于时间与人体关系方面的资料记载,结合本院34年住院心脏病死亡病例,就其死亡时间与人体关系进行分析讨论,应证了时间节律不但存在,而且对疾病的发生发展及预防和治疗都有十分重要意义.     

大气污染物短期效应对上海市浦东新区居民肺癌死亡影响的病例交叉研究

目的 分析大气污染物与浦东新区居民每日肺癌死亡人数的相关性,为制定针对肺癌病人的保护措施提供依据。方法 采集浦东新区2005年1月1日至2019年12月31日之间的每日大气污染物浓度、气象因素以及居民肺癌死亡资料,利用时间分层-病例交叉设计并结合分布滞后非线性模型,探讨大气污染物短期暴露对浦东新区居民肺癌死亡的影响。结果 大气污染物(PM₁₀, SO₂, NO₂)浓度与浦东新区居民肺癌死亡风险呈正相关。PM₁₀, SO₂, NO₂浓度对居民肺癌死亡风险的影响均在累积8 d(Lag 0～7)最强。PM₁₀, SO₂, NO₂浓度上升10 μg/m³累积8 d(Lag 0～7)居民肺癌死亡风险分别上升1.09%(95%CI:0.35%～1.83%), 3.78%(95%CI:1.98%～5.61%)与2.76%(95%CI:1.10%～4.44%)。女性人群肺癌死亡对PM₁₀与NO₂的影响不敏感(P>0.05)。大气污染物对高龄人群与低文化水平人群肺癌死亡效应较强,人群间效应差异不显著。结论 大气污染物短期暴露可以升高浦东新区居民肺癌死亡风险,以累积8 d(Lag 0～7)效应最强。     

1990—2019年中国人群早发性结直肠癌疾病负担及变化趋势分析

目的 分析1990—2019年我国早发结直肠癌（early-onset colorectal cancer,EOCRC）疾病负担及时间变化趋势。方法 利用全球疾病负担2019（Global Burden of Disease 2019,GBD 2019）数据库获取我国14～49岁人群1990—2019年间结直肠癌发病、死亡及伤残调整寿命年（disability-adjusted life years,DALYs）的数量和率,以及危险因素所致EOCRC相关DALYs百分比。计算年龄标化发病率（age-standardized incidence rate,ASIR）及死亡率（age-standardized mortality rate,ASMR）,并用Joinpoint软件对我国EOCRC的ASIR及ASMR行时间变化趋势分析。结果 2019年我国EOCRC新发病例及死亡人数为87383及26274,相比1990年分别增加264.53%及76.92%。我国EOCRC的ASIR及ASMR为10.31/10万及3.07/10万,较1990年分别增加140.32%及14.13%。时间变化趋势分析显示,我国EOCRC的ASIR及ASMR均呈显著上升趋势,其平均年变化百分比（average annual percentage change,AAPC）分别为3.0（95%CI为2.8～3.3）及0.3（95%CI为0.1～0.6）。我国EOCRC相关DALYs为1304828,占我国总体结直肠癌相关DALYs的20.40%及全球EOCRC相关DALYs的30.63%。归因分析提示我国42.85%的EOCRC相关DALYs可归因于饮食、行为及代谢因素。结论 我国EOCRC发病率及死亡率均明显升高,其导致的疾病负担十分严峻。