康复训练对新生大鼠缺血缺氧后大脑皮质一氧化氮合酶阳性神经元的影响

目的　研究康复训练对新生大鼠缺血缺氧后大脑皮质一氧化氮合酶 (NOS)阳性神经元的影响。方法　生后 7dSD大鼠 18只 ,结扎右侧颈总动脉行缺血处理 ;吸入 8%O2 和 92 %N2 行缺氧处理。恢复吸氧后 ,康复组动物进行持续 7d的游泳训练 ,缺血缺氧组动物不进行游泳训练。生后 14dSD大鼠 9只作为正常对照组。取脑进行NADPH d染色 ,定量比较上述 3组动物大脑皮质NOS阳性神经元的数目。结果　大鼠大脑皮质第III、IV、V和VI层均见有NOS阳性细胞分布 ,阳性细胞的胞体大 ,呈多极或梭型 ,可见清晰的胞核 ,突起长且多。大脑皮层NOS阳性神经元数分别为 :正常对照组左侧 ( 191.4± 9.3 )、右侧 ( 190 .2± 6.3 ) ;缺血缺氧组左侧 ( 15 3 .6± 6.4)、右侧 ( 116.4± 11.9) ;康复组左侧 ( 161.8± 10 .1)、右侧 ( 13 8.0± 15 .8)。统计结果显示康复组与缺血缺氧组间右侧大脑皮质NOS阳性神经元数量的差异有显著性意义 (P <0 .0 5 )。结论　持续 7d的游泳训练能促进缺血缺氧新生大鼠大脑皮质NOS阳性神经元的康复。     

Effect of ultrasound on regional cerebral blood flow in neonatal rats

By employing a laser-Doppler flowmeter, an investigation was performed to determine whether ultrasound causes a change in regional cerebral blood flow (rCBF). rCBF in neonatal rats (age: 2–6 days postgestation) was measured before, during, and after exposure of both cerebral hemispheres to continuous-wave ultrasound (1.0 MHz) at an intensity of 2.0 W/cm² (SATA) for a period of 5 min. After 3 min of ultrasound treatment, there was a statistically significant augmentation in rCBF (p < 0.05) with rCBF increasing by a factor of 2.7 ± 0.4 (mean ± SEM) after 5 min of ultrasound. This response was demonstrated to be a transient effect, because rCBF returned to its original value 4–6 min after termination of the ultrasound treatment.     

Synchronized pulsed Doppler blood flow and ultrasonic dimension measurement in conscious dogs

An ultrasonic pulsed Doppler system for sensing blood flow in several vessels simultaneously has been developed and applied in the measurement of blood flow through the smaller vessels of chronically instrumented animals. The range gated, 20 MHz system is directional and can sense Doppler frequencies up to 25 kHz. The probes are single piece cuffs ranging in size from 2 to 8 mm diameter and contain a single piezoelectric crystal 1–2 mm². Calibration curves produced in vivo in dogs show good linearity and reproducibility and agree closely with theoretically predicted values. The pulsed Doppler technique is uniquely suited for synchronization with an ultrasonic transit-time dimension gauge allowing the simultaneous measurement of multiple flows and dimensions. The system has proved to be simple and reliable, and excellent quality signals have been recorded from multiple vessels for periods of several months.     

The influence of visual contrast on visually evoked cerebral blood flow responses

Transcranial Doppler (TCD) could be used to evaluate the visually evoked cerebral blood flow responses (VEFRs) during graded visual cortex activity. The purpose of the study was to evaluate the effects of visual contrasts on VEFR. The records were made from 30 healthy volunteers aged 38.0 +/- 9.6 years. The stimulus was a black-and-white checkerboard with visual contrasts of 1%, 10% and 100%. The VEFRs were measured in the posterior cerebral artery using TCD. We found that the VEFRs at 100% visual contrast were 36% higher than those at 10% visual contrast (p < 0.01). The VEFRs at 10% visual contrast were 81% higher than those at 1% visual contrast (p < 0.01). The linear regression showed significant relationships between the visual contrast and the VEFR (r = 0.61, p < 0.01). We have concluded that TCD monitoring of VEFR detects the changes of the blood flow in the visual cortex and that TCD could allow an assessment of neurovascular coupling.     

A preliminary assessment of an ultrasonic doppler method for the study of blood flow in human breast cancer

A 10 MHz, continuous wave ultrasonic Doppler system was used to study the blood flow associated with normal and malignant mammary tissue in patients with breast cancer. Some patients were receiving endocrine therapy and were examined repeatedly over a period of months. Each of 6 characteristics extracted from the time varying maximum Doppler-shift frequency were averaged over signals obtained from a number of sites in the vicinity of the tumour, and from corresponding sites in the normal breast. A method was devised to allow location of previously examined vessels for subsequent examinations. The preliminary results of analysing approx. 400 recordings of Doppler signals obtained from 16 patients (6 of whom received endocrine therapy) are presented.The most informative of the 6 characteristics were the maximum systolic frequency (A) and the “mean” frequency (M) (=A + B/2 where B is the maximum frequency during end diastole). The average values of A and M obtained from the tumourous breast were always greater than those obtained from the normal breast in the same patient. A and M were roughly proportional to tumour volume, with extrapolated values at zero volume only slightly greater than the corresponding mean values for normal breast tissue. On average, changes in the values of A and M obtained from tumour sites during endocrine therapy appeared to occur in association with, and possibly slightly in advance of, changes in the tumour volume.     

超声监测胎儿及新生儿脑血流进展

脑发育始于胎儿期,脑血流异常是导致儿童脑和神经系统发育不良的主要原因;准确、安全、有效地评估脑血流变化对临床干预和改善患儿预后至关重要。超声是评估胎儿和新生儿脑血流的重要影像学手段。本文就多普勒超声监测胎儿及新生儿脑血流进展进行综述。     

针刺对新生鼠缺血缺氧性脑损伤皮质Nestin表达的影响

目的 观察针刺对新生鼠缺血缺氧性损伤后皮质神经干细胞的影响。方法 新生7d龄SD大鼠72只，随机分为正常组（24只）、新生鼠缺血缺氧性脑病（HIE）模型组（24只）和HIE＋针刺组（24只），3组均于建模后第3，7，14，28天处死取脑，行免疫组化染色，巢蛋白（Nestin）标记神经干细胞。结果 正常SD大鼠生后早期的皮质存在一定数量的Nestin阳性细胞，随年龄增加而减少；缺血缺氧后，新生SD大鼠皮质损伤区及其周围、对侧镜区出现Nestin阳性细胞增多，并以病灶边缘更加突出，伤后3d达高峰，HIE＋针刺组阳性细胞明显增多（P＜0．01），并使高峰时间延长，高峰期推迟，至伤后28 d各组无差异。结论 针刺可促使新生SD大鼠缺血缺氧性损伤后皮质神经干细胞增多，高峰期延长。     

Fetal cerebral blood flow velocity during labor and the early neonatal period.

This study was performed to elucidate circulatory changes in the fetal cerebral circulation during uncomplicated labor and in early neonatal life. Eighteen healthy term singleton fetuses were followed longitudinally during labor. Using the transabdominal approach, and the color Doppler technique, the middle cerebral artery was identified and Doppler flow velocity waveforms recorded between and during uterine contractions. Neonatal recordings were made by insonating the middle cerebral artery from the temporal region before and immediately after the cutting of the umbilical cord, and at 1 hour and 1 day after birth. The recorded Doppler signals were evaluated for pulsatility index, heart rate, peak systolic flow velocity, end-diastolic flow velocity and time-averaged maximum velocity. There was no change in the pulsatility index between and during contractions (1.39 +/- 0.36 and 1.40 +/- 0.39, respectively, mean +/- SD). A significant decrease in the pulsatility index compared to fetal values was seen 4 min after birth (1.06 +/- 0.30, p < 0.01). One hour after birth, the pulsatility index values increased significantly (1.52 +/- 0.25, p < 0.001), to fall again between I hour and 1 day after birth (0.95 +/- 0.26, p < 0.001). Mechanical compression of the skull, blood gas changes and a decrease in ductal shunting may all have contributed to these changes. The present study has shown physiological neonatal circulatory adaptation and onset of breathing to cause manifest changes in cerebral blood flow velocity.     

经颅三维多普勒检测脑震荡患者脑血流演变的特点规律研究

目的探讨脑震荡所致的脑血管痉挛发生机制和尼莫地平治疗脑震荡作用。方法224例脑震荡患者随机分成尼莫地平组(113例)和对照组(111例)应用经颅三维多谱勒(3D-TCD)检测大脑中动脉(MCA),基底动脉(BA)脑血流平均峰流速度,分析脑血流变化规律、特点。结果脑震荡脑血流分为脑血流低灌扩张期、脑血管痉挛期、脑血流恢复期。尼莫地平组在脑血管痉挛期和恢复期临床主要症状消失率明显优于对照组,有非常显著差异(P<0.01)。结论脑血管痉挛和脑缺氧、缺血损害是脑震荡主要病理改变之一,脑神经功能障碍是否可逆,主要取决于脑血管痉挛持续时间长短。     

The effects of sodium nitroprusside on cerebral blood flow and cerebral venous blood gases

Abstract. Cerebral blood flow (CBF) and cerebral venous blood gases were studied in seven patients before, during and after intravenous sodium nitroprusside infusion. The ¹³³Xe intra-arterial injection method was used for the CBF measurements. A dose of sodium nitroprusside (mean 1·0 mg, mean infusion time 20 min), which reduced mean arterial blood pressure by a mean of 17%, resulted in a 13% decrease in CBF ( P <0·05). Measurements obtained 5 and 20 min after termination of the sodium nitroprusside infusion showed no signs of a hyperaemic rebound effect. Arterial PCO₂, metabolic rate of oxygen, arterio-venous oxygen difference and venous PO₂ remained unchanged during and after infusion. It is concluded that sodium nitroprusside has a minor effect on cerebral haemodynamics, an effect that might be mediated by the sympathetic nervous system.     

The effects of cardiopulmonary bypass and deep hypothermic circulatory arrest on blood viscoelasticity and cerebral blood flow in a neonatal piglet model

The purpose of this study is to determine the effects of cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) on the viscoelasticity (viscosity and elasticity) of blood and global and regional cerebral blood flow (CBF) in a neonatal piglet model. After initiation of CPB, all animals (n = 3) were subjected to core cooling for 20 min to reduce the piglets' nasopharyngeal temperatures to 18 degrees C. This was followed by 60 min of DHCA, then 45 min of rewarming. During cooling and rewarming, the alpha-stat technique was used. Arterial blood samples were taken for viscoelasticity measurements and differently labeled microspheres were injected at pre-CPB, pre- and post-DHCA, 30 and 60 min after CPB for global and regional cerebral blood flow calculations. Viscosity and elasticity were measured at 2 Hz, 22 degrees C and at a strain of 0.2, 1, and 5 using a Vilastic-3 Viscoelasticity Analyzer. Elasticity of blood at a strain = 1 decreased to 32%, 83%, 57%, and 61% (p = 0.01, ANOVA) while the viscosity diminished 8.4%, 38%, 22%, 26% compared to the baseline values (p = 0.01, ANOVA) at pre-DHCA, post-DHCA, 30 and 60 min after CPB, respectively. The viscoelasticity of blood at a strain of 0.2 and 5 also had similar statistically significant drops (p < 0.05). Global and regional cerebral blood flow were also decreased 30%, 66%, 64% and 63% at the same experimental stages (p < 0.05, ANOVA). CPB procedure with 60 min of DHCA significantly alters the blood viscoelasticity, global and regional cerebral blood flow. These large changes in viscoelasticity may have a significant impact on organ blood flow, particularly in the brain.     

The influence of brightness,colour and complexity on visual evoked doppler flow responses

The purpose of this study was to evaluate specific influence of colour, brightness and complexity on visual evoked flow responses (VEFRs). A total of 31 healthy subjects aged 35.1 +/- 7.7 years participated in the study. Mean arterial velocity was measured in the right posterior cerebral artery (v(pca)) and in the left middle cerebral artery (v(mca)) by Multi-DopX4 (DWL). Simple-white (SW), red (R) and complex-checkerboard (C) stimuli were used. VEFRs were determined by the difference of the v(pca):v(mca) ratio before and after stimulation. The VEFRs of SW with brightness of 21.4 cd/m(2), 10.5 cd/m(2) and 2 cd/m(2) were 8.7 +/- 3.4%, 9.1 +/- 3.0% and 8.0 +/- 3.7%, respectively (p < 0.001). The VEFRs of R and C stimuli were 10.4 +/- 6.5% and 12.4 +/- 6.1%, respectively (p < 0.001). ANOVA for repeated measurements did not show significant variances (p = 0.295) between VEFRs of SW of different brightness, but variances between VEFRs of SW, R and C stimuli were significant (p < 0.001). We found significant differences between VEFRs of SW and of C stimuli (3.8 +/- 1.9%, p < 0.001), VEFRs of SW and of R stimuli (1.8 +/- 2.4%, p = 0.008) as well as between VEFRs of C and of R stimuli (2.0 +/- 2.5%, p = 0.010). We have concluded that SW, R and C stimuli have a specific influence on VEFRs. Brightness does not appear to affect VEFRs.     

The effects of temperature on blood flow ultrasonic echogenicity in vitro.

An explanation of the mechanism of ultrasonic echogenicity in flowing blood is proposed based upon an in vitro study that indicates a causal relation between red cell aggregation and these echoes. Echogenicity was measured in vitro at 37 degrees, 24 degrees, and 0 degree C as blood flow shear rates were varied. Echogenicity increased at higher temperatures and lower shear rates. The directions of changes in blood echogenicity exactly paralleled previously known changes in red cell aggregation resulting from changes in temperature. The authors consider this to be further evidence that red cell aggregation is an important cause of low-intensity echoes observed in clinical ultrasonography of the heart and circulation.     

The detection of abnormal neonatal cerebral haemodynamics using principal component analysis of the doppler ultrasound waveform

Doppler ultrasound recordings were made from the anterior cerebral arteries of 40 normal full-term babies and 14 mature babies with intracranial pathology. The maximum velocity waveforms were extracted using spectral analysis and further analyzed using the Pourcelot resistance index method and the principal component method. Principal component analysis was found to be superior to the currently widely used resistance index method and may significantly enhance the value of Doppler ultrasound for detecting abnormal cerebral haemodynamics in neonates.     

Measurement of blood flow velocity in the basal cerebral circulation: Advantages of transcranial color-coded sonography over conventional transcranial doppler

Unlike conventional transcranial Doppler (TCD), transcranial color-coded sonography (TCCS) enables imaging of the basal cerebral arteries using color-flow ultrasonography and correction for the angle of insonation when determining blood flow velocities. We present hemodynamic data from 20 normal subjects, each studied with TCD and TCCS. Velocities derived using TCCS with angle correction were significantly greater than those derived using TCD in all vessels (mean velocities [cm/sec; mean with 95% confidence intervals])—anterior cerebral artery: TCD 48 (45–50), TCCS 62 (58–66), p < .0001; middle cerebral artery: TCD 61 (58–64), TCCS 70 (66–74), p < .0001; posterior cerebral artery: TCD 43 (41–46), TCCS 54 (50–57), p < .0001; basilar artery: TCD 40 (34–45), TCCS 45 (38–52), p <.01. Pulsatility index values were significantly greater in all arteries when determined by TCCS, and resistance index values were significantly greater except in the basilar artery. Correcting for the angle of insonation using TCCS may enable estimation of blood flow velocities closer to the “true” values than those derived using conventional TCD. © 1995 John Wiley & Sons, Inc.     

Cerebral blood flow and cerebral metabolism in normal and intrauterine growth retarded neonatal piglets

1. Cerebral blood flow and cerebral metabolism were measured in conscious, normally grown neonatal piglets and in littermates which had undergone intrauterine growth retardation. 2. Cerebral blood flow was measured by the Kety-Schmidt technique using [125I]iodoantipyrine as the tracer. The tissue: blood partition coefficient of this tracer was measured in separate groups of growth retarded and normal animals. Cerebral utilization rates of glucose and oxygen were calculated from the arteriovenous concentration differences on the Fick principle. 3. The mean body weight of the growth retarded animals was about half that of their normally grown littermates, and liver weight was reduced in proportion. Brain weight was slightly but significantly lower in the growth retarded animals. 4. Cerebral blood flow was lower in the growth retarded piglets but the rates of cerebral utilization of oxygen and glucose were not significantly different in the two groups. The fractional extraction of arterial oxygen by the brain was significantly higher in the growth retarded animals. 5. The partition coefficient of iodoantipyrine was significantly lower in the growth retarded animals, being about 75% of the normal value. It is clear that had the partition coefficients been assumed to have been the same in both groups the calculated cerebral blood flows would have been identical. 6. It is concluded that growth retarded neonatal piglets have relatively normal sized brains, with a rate of glucose and oxygen consumption that is not significantly different from normal, despite a reduction in cerebral blood flow of about 35%. Consequently the fractional extraction rate of arterial oxygen by the brain is increased from 50% to 70%.