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31.
Unilateral lesion of the nigrostriatal pathway decreases the firing rate and alters the firing pattern of globus pallidus neurons in the rat 总被引:2,自引:0,他引:2
Activities of spontaneously firing neurons in the globus pallidus of intact rats and rats that survived unilateral lesions of the nigrostriatal pathway for 3 days, 1 week, or 6-11 weeks were compared. No significant differences in neuronal firing rate, firing pattern, and number of cells per pass were observed between chloral hydrate-anesthetized control and lesioned animals. However, in locally anesthetized animals, pallidal cells fired significantly faster than in chloral hydrate-anesthetized animals, and the lesion caused a decrease in the firing rates of pallidal cells 1 week and 6-9 weeks postlesion. In addition, significant differences in the firing pattern of pallidal cells, as determined by the ratio of the mean to median interspike intervals, were seen between locally anesthetized controls and animals surviving 3 days, 1 week, and 6-9 weeks postlesion. This altered firing pattern tended to return to normal with time. The number of cells per pass was not significantly altered by the lesion. Data from this study suggest that, in locally anesthetized animals, the removal of the tonic dopaminergic input to the basal ganglia causes pallidal cells to decrease their firing rates in a time-dependent fashion and causes reversable firing pattern changes. This suggests that tonically active dopamine neurons, probably acting through the striatopallidal pathway, regulate the firing rate and mechanisms controlling the temporal ordering of spontaneous discharges of globus pallidus neurons. 相似文献
32.
Evaluation of renal first pass blood flow with a functional image technique in hypertensive patients
Masatoshi Ishibashi Seiichiro Morita Noriyoshi Umezaki Hisashi Ohtake 《European journal of nuclear medicine and molecular imaging》1988,14(1):25-27
The renal circulation of patients with essential hypertension and renovascular hypertension was evaluated using 99mTc-DTPA. The first renal peak count (the first Cmax; FCmax), time phase distribution (the first Tmax; FTmax), and blood velocity (the FCmax/FTmax) were calculated by digital imaging. This yields a visual image of the renal circulation. We consider that the increase in the renal first pass blood flow in patients with essential hypertension is best observed pixel by pixel. The FCmax and FCmax/FTmax images before and after treatment by percutaneous transluminal renal angioplasty in patients with renovascular hypertension clearly show its therapeutic effect. The FI technique, therefore, has the advantage that it can be performed at the same time as the conventional routine examinations of renal function. This makes it very useful clinically. 相似文献
33.
Masaki Shinoda Tsuyoshi Yamaguchi Yoshimi Tanaka Osamu Sato Sin Kobayashi Yutaka Suzuki 《Child's nervous system》1992,8(4):219-221
Single photon emission computerized tomography (SPECT) is now widely used as one of the tools in evaluating cerebral blood flow (CBF). The authors report the CBF changes in childhood hydrocephalus. Five pediatric cases studied by 123I-IM SPECT in children are presented. The authors counted radioactivities both in early and delayed images in each patient, and calculated the reabsorption ratio (RR). Two negative-RR cases and three positive-RR cases were found. All of the negative-RR patients had a poor prognosis, while all of the positive-RR patients had a favorable outcome. 相似文献
34.
用单板计算机配合肾图仪,可自动采集肾图数据、计算并打印指标及曲线.75例病人的配对比较结果表明:计算机结果与原肾图仪无显著性差异.由此证明我们编制的应用程是合理可行的. 相似文献
35.
目的:分析74例更换起搏器时电极导线的各项参数的变化并探讨导线更换指标。方法:本组年龄12~87(62.8±18.4)岁,其中病窦综合征45例,房室传导阻滞29例,均为单腔VVI起搏。结果:至测量时原心室起搏电极导线的埋置时间60~148(97.4±22.8)月,首次埋置时起搏阈值为(0.48±0.24)V,更换时为(1.29±0.64)V(P(0.01),增加0.81V,增幅为168%,首次植入时R波幅为(7.8±3.6)mV,更换时为(5.9±3.4)mV(P(0.05)。植入时电极导线阻抗为(664±122)Ω,更换时阻抗为(726±148)Ω,增幅9.3%(P(0.05)。7例因起搏阈值大于2.0 V或阻抗大于1 250Ω而重新植入电极导线。原电极导线使用率为90.5%。结论:埋置起搏电极导线8~9年后,90.5%原电极导线仍在可使用的范围内,能否支持到再次更换需进一步随访。 相似文献
36.
37.
H. Oka T. Yamamoto T. Kawazoe K. Saratani Y. Hikida 《Medical & biological engineering & computing》1988,26(3):260-266
A new impact response method using a fracture of a pencil-lead to produce an excitation pulse is proposed. Impact excitations
(rectangular pulse, triangular pulse and half-sine pulse) are strictly given in physical and mathematical definitions and
complete solutions to the impact excitations are provided for Noyes' model of the human tooth. When a relatively long triangular
pulse is applied to Noyes' model, which can express the physical characteristic of periodontal tissues, a sinusoidal damped
vibration of a single degree-of-freedom model is approximately obtained. The acceleration response is characterised by the
physical parameters (T, δ and Ao) and mechanical elements (m1, c1 and k) of which a single degree-of-freedom model is composed. By means of this method, the values of the parameters and elements
in the cases of healthy maxillary, healthy mandibular and pathological mandibular incisors are obtained. The single degree-of-freedom
model can express the high-frequency spectra of Noyes' model. The pathological tooth is characterised by a longer damped time
constant and a larger acceleration maximum. This impact response method can effectively be applied to clinical diagnosis in
view of the physical parameters and mechanical elements which have been derived. 相似文献
38.
MRI and SPECT findings in amyotrophic lateral sclerosis 总被引:1,自引:0,他引:1
Summary MRI was performed in 21 patients and single photon emission computed tomography (SPECT) withN-isopropyl-p-123I iodoamphetamine in 16 patients, to visualize upper motor neurone lesions in amyotrophic lateral sclerosis. T2-weighted MRI revealed high signal along the course of the pyramidal tract in the internal capsule and cerebral peduncle in 4 of 21 patients. SPECT images were normal in 4 patients, but uptake was reduced in the cerebral cortex that includes the motor area in 11. 相似文献
39.
James A. Case Bai Ling Hsu Timothy M. Bateman S. James Cullom 《Journal of nuclear cardiology》2007,14(3):324-333
Background High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed
tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission
data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data.
Methods and Results The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially
weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and
bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom
studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the
phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients
(mean SD, 0.005 cm−1 vs 0.011 cm−1; P<.0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas
both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall
variability (4.8% to 4.1%, P=.02) for all BMI groups with the new method compared with FBP.
Conclusion This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum
of patient BMI values and significantly improves attenuation-corrected perfusion images. 相似文献
40.