电刺激膈神经中枢端引起降压反应的外周机理

电刺激麻醉家兔膈神经中枢端呆引起动脉血压下降，此降压反应不能被剪断双侧迷走神经所阻断；但可被静脉注射心得１．０ｍｇ／ｋｇ部分阻断；也可被静注射酚妥拉明２．０ｍｇ／ｋｇ部分阻断，去除缓冲神经后其降压效应更为明显。     

CD4-positive/heat-stable antigen-positive thymocytes cause graft-versus-host disease across non-major histocompatibility complex incompatibilities

Single-positive thymocytes are the immediate precursors of peripheral recent thymic emigrants (RTE) which develop into mature peripheral T cells. The functional ability of RTE is unclear but their state of differentiation may be relevant to the development of tolerance to peripheral “self” antigens. Since RTE are difficult to analyze, precursor CD4⁺/8⁻ thymocytes were assessed in a model in vivo to determine their functional capability and their susceptibility to tolerance induction. The ability of both heat-stable antigen-positive (HSA⁺) (immature) and HSA⁻ (mature) single-positive thymocytes to cause graft-versus-host disease (GVHD) across non-major histocompatibility complex differences was examined. Both HSA⁻ and HSA⁺ CD4⁺/8⁻ thymocytes from C3H mice caused lethal GVHD in AKR recipients as did CD4⁺ peripheral T cells in controls. Further, neonatal C3H thymocytes also caused lethal GVHD in AKR recipients. Since CD4⁺/8⁻ thymocytes are the precursors of RTE, these results suggest that RTE are not susceptible to tolerance induction to “minor” antigens and may have a normal immune function in vivo. This would suggest that peripheral tolerance may be dependent upon the manner of antigen presentation rather than T cell maturity.     

Assessment of exposure to arsenic among smelter workers: A five-year follow-up

In a group of 43 smelter workers exposed to inorganic arsenic dust for 13-45 years, nerve conduction velocities (NCVs) were significantly lower in two peripheral nerves as compared with matching referents. With multivariate data analysis, a significant negative correlation was found between cumulative absorption of arsenic and NCV in four examined nerves and the sural amplitude. Clinical symptoms of neuropathy and other symptoms related to arsenic exposure were moderate, though the difference between the groups was significant. The mean total absorption of arsenic was calculated to be less than 5 g, and the maximal absorption about 20 g. These data indicate that the adverse effect of arsenic on the peripheral nerves is dependent on long-term exposure rather than on short-term fluctuations in exposure levels. © 1994 Wiley-Liss, Inc.     

平板式全数字心血管造影机在周围血管及非血管介入中的应用

目的 :评价平板式全数字心血管造影机在周围血管及非血管介入中的应用价值。方法 :对平板探测器(FPDD)X线成像与影像增强器 电视 (IITV)X线成像在动态范围、成像均匀性、对比度线性、对比分辨率等图像质量指标的检测及比较。随机选择上述两机型在周围血管及非血管介入诊疗病例图像资料各 6 0例 ,由三名高年资医师对其图像质量进行综合评价 ,记录评价结果 ,并进行比较。结果 :FPDD成像在动态范围、成像均匀性、对比度线性、对比分辨率等图像质量指标均优于IITV成像 ;在人体各部位周围血管及非血管介入诊疗中的图像综合评价结果也优于IITV成像。结论 :平板式全数字化心血管造影机不仅适用于心血管介入 ,同时能满足全身各部位周围血管及非血管介入诊疗的需要。     

生物人工周围神经修复大鼠不同长度周围神经缺损

目的 采用一种自行研制的具有良好生物相容性的部分脱乙酰甲壳质构建人工神经来修复大鼠坐骨神经不同长度的缺损，研究证实其修复效果。方法 选用24只健康雄性SD大鼠，随机分为3组造成不同长度（5、10、15mm）的坐骨神经缺损，右侧进行人工神经桥接修复，左侧进行原位神经移植。12周后进行神经电生理检测以及组织学检测。结果 5mm以及10mm组，光镜下能够观察到人工神经内新生的纤维延续存在。组织学证明。此种人工神经能够有效的修复10mm以内的大鼠坐骨神经缺损；神经肌肉复合动作电位的产生表明：12周后神经已经长过缺损段，神经传导功能恢复，并且已经长入远端靶器官。结论 结果证明这种套管能够有效的桥接10mm的大鼠坐骨神经缺损（神经直径的6～8倍）。可能应用于周围神经缺损的治疗。同时可以作为进一步开发组织工程化的人工神经的良好载体。     

陈旧性Denis Ⅱ型骶骨骨折合并骶神经损伤的诊断与治疗

目的：探讨陈旧性Denis Ⅱ型骶骨骨折合并骶神经损伤的诊断及手术方法。方法：取60具骶骨干标本及26具完整骨盆标本，测量S1棘突与S1后孔同位置关系、骶前区血管、骶神经及梨状肌之间关系；对14例陈旧性DenisⅡ型骶骨骨折合并骶神经损伤患者，在常规骨盆X线片，CT，螺旋CT三维重建的同时，又采用显示骶神经全长的骶骨斜冠状位MR扫描，观察神经走向及眦领关系。11例行自行设计的后略骶神经管扩大减压术，3例行非手术治疗。结果：S1棘突于S1后孔中上1/3者占90%，骶前区主要血管有骶外侧动静脉和骶外侧血管、骶正中血管及臀上血管进入骶前孔的分支。血管位于骶丛神经腹侧，骶外侧斑管距离S1前孔大于10mm，S2前孔大于5mm。骶骨斜冠状位MR扫描可以显示骶神经全长及周围眦领关系。骶神经损伤时，发现有神经根走行改变(13例），损伤处神经很周围脂肪消失（11例），神经根管狭窄(10例)。14例均获得随访。随访时间6--12个月。平均7.1个月，术后改善情况，优9例，无变化1例。结论螺旋CT三维重建及骶骨斜冠状位MR扫描对于骶神经损伤的定位及定性诊断有重要价值。后路骶神经管扩大减压术是针对骶神经管、骶前孔处神经损伤的较理想手术方法。     

Nd:YAG激光虹膜周边切除术治疗闭角型青光眼的临床研究

目的探讨Nd：YAG激光虹膜周边切除术治疗闭角型青光眼的疗效。 方法26例30只眼闭角型青光眼分为AB两组，A组为中周部高能量组（首次击射能量为7．4mJ），B组为极周边部低能量组（首次击射能量为5．3mJ），行Nd：YAG激光虹膜周边切除术。 结果两组患者均穿孔成功，A组并发症较B组明显减少，且一次穿孔率达100％。 结论Nd：YAG激光虹膜周边切除术治疗闭角型青光眼疗效可靠，并发症少，值得推广应用。     

Technetium-99m sestamibi scintigraphy for the assessment of lower extremity ischaemia in peripheral arterial disease

Technetium-99m sestamibi was used for functional investigation of the muscle perfusion of lower extremities in 35 patients with peripheral vascular disease. The aim was to test what useful information could be obtained by additional imaging of the legs in patients referred for risk stratification with dipyridamole myocardial scanning. Posterior images were acquired over the thighs and calves after postocclusive reactive hyperaemia and at rest. Inter- and intraextremity ratios and differences between the stress and rest data were used for the assessment of abnormal circulation. Arteriography was performed in every case, and surgical procedures or transluminal angioplasty in 31 patients. To estimate diagnostic accuracy, the results of^99mTc-sestamibi scintigraphy were compared with those of angiography and the functional consequences of revascularization procedures. The sensitivity and specificity of^99mTc-sestamibi scintigraphy were 55% and 25%, respectively, with an overall accuracy of 50%. Apparently methodological error was not responsible for these poor results. Instead, a paradoxically high uptake of the radiopharmaceutical in muscles supplied by significantly stenosed vessels was identified as the main source of both false-negative and false-positive results. This phenomenon resembles the findings of a previous study involving delayed administration of thallium-201 after exercise. In conclusion,^99mTc-sestamibi scintigraphy has not proved sufficiently reliable to help in the management strategy for patients with peripheral vascular disease.     

Peripheral nerve stimulation during MRI: Effects of high gradient amplitudes and switching rates

The application of high gradient amplitudes and switching rates for MRI and spectroscopy, resulting in short rise times for the gradient field and high changes of the magnetic flux density in the patient, is known to possibly evoke peripheral nerve stimulation (PNS) in patients. These effects have been studied on 20 volunteers under different experimental circumstances. The results of these measurements are partially in line with earlier findings reported in the literature. New information is found for the dependence of the PNS threshold level as a function of the rise time of the gradient waveform. The PNS threshold level, expressed in terms of dB/dt, is found to be proportional with t^?05, where t is the switch time for the gradients. Indications are found that |B|, the modulus of the gradient vector field, is more closely related to the PNS threshold level than B_z, the imaging component of the gradient field. From the experiments, it is furthermore concluded that only for the imaging protocols characterized by the application of long bipolar repetitive gradient pulse trains, such as echo-planar imaging, PNS is expected at the reported threshold levels. For the protocols based on spin echo, turbo spin echo, inversion recovery, fast field echo, etc., characterized by shorter gradient pulse trains, the threshold levels are expected to be much higher.     

Ulnar distribution of reflex sympathetic dystrophy due to compression of the brachial plexus by a primary venous malformation

An atypical variant of reflex sympathetic dystrophy (RSD) is presented in a 45 year old female with a vascular malformation of the right arm and chest wall. The mechanism was thought to be compression of the brachial plexus by the malformation. The unique scintigraphic features of this presentation of RSD in the ulnar arterial distribution are illustrated.