Changes in regional cerebral blood flow following stereotactic psychosurgery.

Serial measurements of regional cerebral blood flow by the 133Xe inhalation method were performed in a pilot study in 6 patients undergoing stereotactic psychosurgical procedures (anterior capsulotomy, cingulotomy, frontobasal tractotomy). Average hemispheric flow did not change significantly from pre- to post-operative, but changes were seen in the patterns of regional flow distribution. The most striking finding was frontal flow reduction following capsulotomy. In view of the coupling of blood flow and function in the brain, the results indicate that this method offers a new way for exploring the effects of functional neurosurgery on brain activity.     

Changes in regional cerebral blood flow distribution during postexercise hypotension in humans.

This investigation compared patterns of regional cerebral blood flow (rCBF) during exercise recovery both with and without postexercise hypotension (PEH). Eight subjects were studied on 3 days with randomly assigned conditions: 1) after 30 min of rest; 2) after 30 min of moderate exercise (M-Ex) at 60-70% heart rate (HR) reserve during PEH; and 3) after 30 min of light exercise (L-Ex) at 20% HR reserve with no PEH. Data were collected for HR, mean blood pressure (MBP), and ratings of perceived exertion and relaxation, and rCBF was assessed by use of single-photon-emission computed tomography. With the use of ANOVA across conditions, there were differences (P < 0.05; mean +/- SD) from rest during exercise recovery from M-Ex (HR = +12 +/- 3 beats/min; MBP = -9 +/- 2 mmHg), but not from L-Ex (HR = +2 +/- 2 beats/min; MBP = -2 +/- 2 mmHg). After M-Ex, there were decreases (P < 0.05) for the anterior cingulate (-6.7 +/- 2%), right and left inferior thalamus (-10 +/- 3%), right inferior insula (-13 +/- 3%), and left inferior anterior insula (-8 +/- 3%), not observed after L-Ex. There were rCBF decreases for leg sensorimotor regions after both M-Ex (-15 +/- 4%) and L-Ex (-12 +/- 3%) and for the left superior anterior insula (-7 +/- 3% and -6 +/- 3%), respectively. Data show that there are rCBF reductions within specific regions of the insular cortex and anterior cingulate cortex coupled with a postexercise hypotensive response after M-Ex. Findings suggest that these cerebral cortical regions, previously implicated in cardiovascular regulation during exercise, may also be involved in PEH.     

Regional cerebral blood flow of the rat in acute carbon monoxide intoxication.

The effect of carbon monoxide (CO) on the regional cerebral blood flow was studied by exposing lightly anesthetized rats for 30 min to 0.5, 1.0, 1.5, and 2.0% CO gas mixtures. Cortical cerebral blood flow (CBF) increases of near 200%, 300%, and 400% control were observed at 0.5, 1.0, and 1.5% CO, respectively; whereas at 2.0% CO a reversal of the CBF increase was observed with values declining to near 300% control. The CBF response of subcortical, cerebellar, and brain stem areas was quantitatively similar to that of cortex, indicating that the CBF changes in CO intoxication are general. The decrease in CBF at 2.0% CO was related to significant decreases in arterial CO2 tension. Comparison of the CBF data to previous metabolic results in CO poisoning suggests that the CBF increases are a principal factor in the maintenance of an intact energy state in CO poisoning.     

Total and regional cerebral blood flow during moderate and severe exercise in miniature swine.

To determine the influence of exercise on cerebral blood flow, we ran 14 swine at 3-6 mph and at 0-10% grades on a treadmill for 30 min at moderate and severe levels of exercise. Measuring heart rate, cardiac output, and aortic pressure via implanted probes, we injected 15-mum radiolabeled microspheres via the left atrium before and during exercise. We measured their distribution by gamma spectrometry, determining total cerebral blood flow, regional blood flow, and ratio of flow to gray and white matter. Heart rate, cardiac output, and aortic pressure rose progressively with increasing exercise. Total cerebral flow resembled that reported in humans, i.e., it did not change significantly with exercise. Regional flow distribution also failed to change significantly with exercise. The ratio of gray to white matter flow did not change except to the cerebellum where it rose significantly from resting values at both moderate and severe exercise. Gray matter received more flow than white matter during all three conditions of observation. Cerebral blood flow was remarkably constant during even severe exercise.     

急性脑梗死患者相关生化指标检测的临床意义

目的：探讨急性脑梗死（ACI）患者治疗前后Hcy、ET-1、hs-CRP、TXA2水平和凝血纤溶指标的变化及临床意义。方法：分别采用ELISA法、发色底物法、凝血酶法、放射免疫法和免疫透射比浊法对68例ACI患者治疗前后Hcy、ET-1、hs-CRP、TXA2和各凝血纤溶指标水平进行检测,并以30例正常健康人作为对照组。结果：①ACI患者治疗前血浆Hcy、ET-1和血清hs-CRP、TXA2含量高于对照组（P〈0.01）,经过治疗,含量均明显下降,其中血浆Hcy、ET-1恢复至正常水平,与对照组间比较差异无统计学意义（P〉0.05）②轻、中、重型组间血浆ET-1和血清hs-CRP、TXA2含量逐渐增加,组间差异有显著性（P〈0.01或0.05）,而中重型患者血浆Hcy含量明显高于轻型患者（P〈0.01）。③经过治疗,ACI患者血浆vWF、GMP-140、Fg和F1＋2含量较治疗前显著下降,而血浆PS活性、PC活性与AT水平较治疗前明显上升（P〈0.01）,其中血浆PS和PC活性与对照组间比较差异无统计学意义（P〉0.05）。④ACI患者血浆中tPA水平低于对照组,血浆PAI-1含量高于对照组（P〈0.01）。治疗后血浆tPA增加,与对照组间差异无统计学意义（P〉0.05）,PAI-1减少,但仍显著高于对照组（P〈0.05）。结论：检测急性脑梗死（ACI）患者Hcy、ET-1、hs-CRP、TXA2和凝血纤溶指标水平的变化对于指导用药、病情观察和预后评估均有重要的临床意义。     

Microsphere maps of regional blood flow and regional ventilation.

Systematically mapped samples cut from lungs previously labeled with intravascular and aerosol microspheres can be used to create high-resolution maps of regional perfusion and regional ventilation. With multiple radioactive or fluorescent microsphere labels available, this methodology can compare regional flow responses to different interventions without partial volume effects or registration errors that complicate interpretation of in vivo imaging measurements. Microsphere blood flow maps examined at different levels of spatial resolution have revealed that regional flow heterogeneity increases progressively down to an acinar level of scale. This pattern of scale-dependent heterogeneity is characteristic of a fractal distribution network, and it suggests that the anatomic configuration of the pulmonary vascular tree is the primary determinant of high-resolution regional flow heterogeneity. At approximately 2-cm(3) resolution, the large-scale gravitational gradients of blood flow per unit weight of alveolar tissue account for <5% of the overall flow heterogeneity. Furthermore, regional blood flow per gram of alveolar tissue remains relatively constant with different body positions, gravitational stresses, and exercise. Regional alveolar ventilation is accurately represented by the deposition of inhaled 1.0-microm fluorescent microsphere aerosols, at least down to the approximately 2-cm(3) level of scale. Analysis of these ventilation maps has revealed the same scale-dependent property of regional alveolar ventilation heterogeneity, with a strong correlation between ventilation and blood flow maintained at all levels of scale. The ventilation-perfusion (VA/Q) distributions obtained from microsphere flow maps of normal animals agree with simultaneously acquired multiple inert-gas elimination technique VA/Q distributions, but they underestimate gas-exchange impairment in diffuse lung injury.     

Effect of microwave radiation on regional blood flow and tissue oxygenation in the brain

The effect of irradiation of the central nervous system by microwaves (MW) at a frequency of 2450 MHz and power 5-40 W on the regulation of cerebral circulation and oxygen supply to the nervous tissue were studied in rabbits. Local irradiation of the exposed cerebral cortex resulted in hyperemia and hyperoxia in the zone of exposure induced by the hyperthermal effect of MW. When the region of the medulla oblongata was irradiated even with low MW power (not leading to hyperthermia), the local circulation and oxygen tension increased in the whole brain, apparently due to the impairment of the regulation of the cerebral blood flow and oxygen supply to the brain tissue.     

Effect of the limbic cortex on regional lymph and blood flow in dogs]

Electrical stimulation of the anterior limbic area of the cortex in dogs resulted in increase of the lymph flow from the intestinal lymph duct, in enlargement of the mesenteric lymph nodes, in a fall of arterial pressure in the cranial mesenteric artery, and in decrease of the blood-stream from the homonymous vein and in the tone of the mesenteric veins. Constriction of the mesenteric veins and increase in the intestinal lymph-stream are considered to be a compensatory reaction to restore the arterial pressure to the initial level.     

Effect of acetazolamide on cerebral blood flow and tympanic temperature in healthy subjects and patients with subacute subarachnoid haemorrhage

The influence of the increased cerebral blood flow (CBF) induced by acetazolamide on tympanic temperature (T _ty) was examined in three healthy male volunteers and in five patients with subacute subarachnoid haemorrhage (SAH). The CBF was estimated by means of stable xenon-enhanced computed tomography before and after the administration of acetazolamide. The T _ty was recorded continuously in both ears using thermistor thermometers. In all subjects, CBF increased ranging from 11% to 108% after acetazolamide administration. In all the healthy subjects and in two patients with mild SAH, T _ty was higher than the oesophageal temperature (T _oes) and T _ty decreased bilaterally, ranging from 0.07 to 0.35°C as CBF increased. Three patients with severe SAH were febrile, their T _oes exceeding T _ty, and their T _ty rose by 0.30 to 0.53°C with increased CBF. These observations suggest that T _ty follows brain temperature which changes with an increase in CBF in euthermic subjects as well as in febrile subjects. Accepted: 3 September 1996     

Changes of regional myocardial blood flow during and after acute focal experimental ischaemia.

The regional blood flow through the myocardium of the left ventricle was measured in 11 dogs after ligation of the left anterior descending coronary artery, by means of a local injection of 133Xe depot and precordial detection of its washout 2 hours after ligation. Immediately after ligation the blood flow in the ischaemic area declined considerably but at the same time there was a significant increase of blood flow in the non-ischaemic left ventricular myocardium. The regional flow in the ischaemic and non-ischaemic area increased insignificantly for 2 hrs. These changes were not due to alterations in coronary artery pressure, as the mean arterial pressure declined significantly during the first hour. After temporary ischaemia by ligation of the left anterior descending coronary artery for 2--4 minutes, an intensive reactive hyperaemia developed in the ischaemic region (the blood flow reached 221% of control values on the average) which was the more intensive, the greater the drop of blood flow in the ischaemic area after ligation.