bluuebunny/crossref_metadata_2025 huggingface dataset:
Anatomic and Hemodynamic Correlations in Carotid Artery Stenosis
Authors: DEWEESE JAMES A. , MAY ALLYN G. , LIPCHIK ELLIOT O. , ROB CHARLES G.
Published: June 2011

Pressures were measured in the carotid arteries of 61 patients proximal and distal to atherosclerotic plaques which were carefully studied by angiography and anatomical dissection.

(1) An atherosclerotic plaque causing a constriction of less than 47% luminal diameter leaving a lumen greater than 3.0 mm in diameter never caused pressure drops of greater than 10 mm Hg. Stenoses of greater than 63% luminal diameter leaving lumens less than 1.0 mm in diameter always caused pressure drops.

(2) Atherosclerotic plaques producing defects which narrowed the lumen fell into a distinct pattern:

(a) Type 1 lesions—This basic lesion filled the bulb of the internal carotid artery near its origin, causing a 1 to 2 cm smooth elliptical encroachment on the lumen.

(b) Type 2 lesions—Short localized areas of thickening in addition to the basic lesion caused bar-like defects of the lumen at the origin of the internal carotid artery or near the distal end of the lesion.

(c) Type 3 lesions—Multiple bar-like defects were sometimes seen.

(d) Type 4 lesions—The areas of increased thickening of the lesion were sometimes quite narrow, producing diaphragm-like defects on the lumen.

Although theoretically these various types of stenoses should produce different hemodynamic changes, insufficient numbers of observations were made to corroborate these presumptions.

(3) Angiograms in general mimicked the gross appearance of the plaques and predicted the actual degree of stenosis produced but did not identify many diaphragm defects, ulcerations, or small thrombi.
Effects of Breathing O
2
or O
2
+ CO
2
and of the Injection of Neurohumors on the PO
2
of Cat Cerebral Cortex
Authors: WHALEN WILLIAM J. , GANFIELD ROGER , NAIR PANKAJAM
Published: June 2011

Tissue PO
2
was measured in the outer 1.7 mm of the brain of the lightly anesthetized cat by means of a micro O
2
electrode introduced through a small hole in the skull. There was considerable variation from one location to another and from animal to animal. The interindividual variation was not related to the level of the arterial pressure or to rectal temperature. Individual values for the PO
2
in 569 locations in the 11 cats ranged from 0 to 90 mm Hg with a mean of 25. There was a significant downward trend in PO
2
from the surface layers inward. When the electrode was left in one location, the PO
2
usually fluctuated, though not often rhythmically as seen in skeletal muscle. Breathing pure O
2
(N=41) or 95% O
2
– 5% CO
2
(N = 33) caused an equal (50%) increase in PO
2
. The intravenous injection of epinephrine or norepinephrine caused a primary rise in PO
2
usually with a secondary decrease. Acetylcholine caused a primary decrease and usually a secondary increase.
Experimental Cerebral Infarction. II. Clinicopathological Model of Deep Cerebral Infarction
Authors: MOLINARI GAETANO F.
Published: June 2011

Injection of silicone rubber cylinders into the internal carotid system permits selective occlusion of the proximal middle cerebral artery segment in the dog. Occlusions of this segment obstruct the mouths of the lenticulostriate arteries and result in deep cerebral hemisphere infarctions.

Surface vessels distal to the occluded segment remain patent and the cortex of the hemisphere is spared, due to efficient collateral circulation.

Hemorrhage in cortical infarctions may occur distal to the point of vascular occlusion and, therefore, may be a function of patent meningocerebral anastomoses.

Hemorrhage into a deep infarction, however, occurred only when there was clinical and pathological evidence of distal migration of the embolus after an initial proximal occlusion.

Infarctions of deep hemisphere structures were otherwise bland or "ischemic," probably because of the paucity of anastomoses among the penetrating blood vessels of the brain.
Nonembolic Occlusion of the Middle Cerebral and Carotid Arteries—A Comparison of Predisposing Factors
Authors: HEYDEN SIEGFRIED , HEYMAN ALBERT , GOREE JOHN A.
Published: June 2011

Selected clinical characteristics of patients with nonembolic occlusion of the middle cerebral artery were compared with those of patients with atherosclerotic occlusive lesions at the bifurcation of the common carotid artery. Unexpected differences were observed in the race-age distribution, in the presence of systemic vascular disease, and in the frequency of factors predisposing to atherosclerosis. The group with intracranial arterial lesions included more Negro patients than the group with lesions in the extracranial carotid artery. Ischemic heart disease, intermittent claudication and hypercholesterolemia were more frequent among the patients with extracranial cerebrovascular lesions, but the incidence of hypertension and diabetes was the same in both groups. These findings suggest differences in the etiological and pathogenetical mechanisms of the vascular disease in patients with extracranial and intracranial cerebral arterial occlusive lesions.
Temporary Occlusion of the Middle Cerebral Artery in the Monkey: Clinical and Pathological Observations
Authors: CROWELL ROBERT M. , OLSSON YNGVE , KLATZO IGOR , OMMAYA AYUB
Published: June 2011

The right middle cerebral artery (MCA) was exposed in monkeys via a retro-orbital microsurgical approach. In 43 animals a temporary occlusive clip was placed on the MCA origin for one to 24 hours. In 20 animals, the origin of the MCA was permanently occluded.

Clinical evaluation of the monkeys one to three days postoperatively showed that one to two-hour clipping caused no or mild neurological deficits, four-hour clipping caused mild to moderate deficits, six to eight-hour clipping caused moderate to severe deficits, and 24-hour clipping produced severe deficits or death, a result equivalent to that produced by permanent occlusion. Gross and microscopical evaluation of the brains showed that one to two-hour clipping usually caused no or mild damage, four-hour clipping caused mild to moderate damage (often with capsular sparing), and six to eight-hour clipping and 24-hour clipping produced severe extensive infarction not different from that caused by permanent occlusion. Six to eight-hour clipping and 24-hour clipping were associated with a high incidence of hemorrhagic infarction, but other clipping times were not. The results suggest that reestablishment of flow by surgical means within a few hours after MCA occlusion in selected patients might result in significant restoration of neurological function. If flow renewal were done within about four hours, an increased incidence of hemorrhagic infarction might be avoided.
An Epidemiological Study of Hemiplegia due to Stroke in South India
Authors: ABRAHAM J. , RAO P. S. S. , INBARAJ S. G. , SHETTY G. , JOSE C. J.
Published: June 2011

The findings of a preliminary epidemiological survey of Vellore, South India, and adjoining rural areas are presented. The prevalence of "completed strokes" and hemiplegias due to any cause is 56.9 per 100,000. The high incidence of hemiplegia in the young has been pointed out. The need for concerted efforts for a proper evaluation of the incidence of cerebrovascular disease in India seems imperative.
Brain edema and blood-brain barrier permeability following quantitative cerebral microembolism.
Authors: Bralet A M , Beley A , Beley P , Bralet J
Published: June 2011

Cerebral microemboli were formed in rats by injecting 4,000 carbonized microspheres, 50 +/- 10 mu in diameter, labelled with 85Sr, into the internal carotid artery. The use of radioactive microspheres as embolic agents enabled the number of microspheres to be determined in each cerebral hemisphere. The microspheres were mainly distributed in the cerebral hemisphere on the side of the injection. In 61 rats this hemisphere contained 582 +/- 20 microspheres against 99 +/- 9 in the contralateral hemisphere. Brain edema was assessed by measuring brain content of water, sodium and potassium. Blood-brain barrier (BBB) permeability was determined by brain accumulation of 125I-albumin. In the ipsilateral hemisphere brain edema and an increase in BBB permeability appeared 6 hours after embolization and progressed up to 48 hours. Twenty-four hours after embolization, significant correlations were observed between the microsphere content of the cerebral hemispheres and 1) the increases in water and sodium levels, 2) the decrease in potassium level, 3) the increase in BBB permeability. The study of these correlations should make it possible to ignore the poor reproducibility of embolizations and to analyze with increased accuracy the results of various experiments.
Pathophysiological mechanisms of brain edema development: role of tissue factors.
Authors: Mchedlishvili G , Nikolaishvili L , Itkis M
Published: June 2011

In experiments carried out on adult rabbit "chest-head" preparations the volume changes of the exposed brain (BrV) were determined in repeated tests during a controlled increase of the systemic venous pressure (SVP) of about 13 mm Hg. The changes of both SVP and BrV were usually parallel at the onset of the experiments, but when the brains became preedematous hysteresis appeared in the plots of their relationships. The hysteresis increased gradually (sometimes with periods of partial decrease) thus indicating a delay in the draining of blood from the brain's venous system and in the removal of excess extracellular fluid from the cebral tissue. Evidence for water filtration through the capillary walls during increase of the SVP, and, thus, of brain intravascular pressure, was obtained by detecting the dynamics of [Na+] and [K+] in the extracellular fluid of the cerebral cortex by ion-selective electrodes. This process appeared reversible in normal brains while in the preedematous ones the excessive water filtration resulted in brain edema. The preedematous state of the brain is believed to be caused by changes of the mechanical properties of brain tissue and/or by changes in osmolarity.
Ischemic brain edema: comparative effects of barbiturates and hypothermia.
Authors: Simeone F A , Frazer G , Lawner P
Published: June 2011

The effect of pentobarbital and hypothermia on the development of ischemic brain edema was studied in 23 rhesus monkeys undergoing transorbital middle cerebral artery occlusion. Fifteen additional animals served as unclipped controls. Regional cortical cerebral blood flow (rCBF), arteriovenous oxygen content difference (AVDO2), and regional cortical metabolic rate of O2 (rCMRO2) were measured hourly until sacrifie 11 hours postocclusion, at which time ischemic cerebral edema was measured. In 8 animals no treatment followed the occlusion, and these developed edema. In 7 animals pentobarbial 14 mg/kg was administered intravenously 30 min after occlusion and 7 mg/kg every 2 hours thereafter. In this group ischemic brain edema was negligible. In 8 animals, hypothermia to 25.9 +/- 0.5 degrees C was started 30 min after occlusion and maintained until sacrifice; ischemic brain edema was not significantly altered from untreated-clipped animals. On the basis that both pentobarbital and hypothermia produced similar changes in rCBF, AVDO2, and rCMRO2, but only pentobarbital prevented edema, it is postulated that the mode of action of barbiturates in preventing ischemic brain edema is not entirely related to their known effect on blood flow and metabolism.
Intracranial saccular aneurysm and moyamoya disease.
Authors: Adams H P , Kassell N F , Wisoff H S , Drake C G
Published: June 2011

Moyamoya disease is a rare but well described entity which has been found in the angiographic investigation of subarachnoid hemorrhage, its most common symptom in adults. We present 4 patients in whom moyamoya disease and an intracranial saccular aneurysm were discovered. In 2 of the 3 patients suffering a hemorrhage, the aneurysm was the source of bleeding. Three of the aneurysms were located at the basilar artery bifurcation. We recommend a careful search for a concomitant aneurysm in all patients with subarachnoid hemorrhage in whom moyamoya disease is found. We believe these patients should be treated as though the aneurysm were the source of bleeding.
Adrenergic control of cerebral blood flow and energy metabolism in the rat.
Authors: Kogure K , Scheinberg P , Kishikawa H , Utsunomiya Y , Busto R
Published: June 2011

Studies in rats were designed to separate and define the roles of the intrinsic and extrinsic adrenergic neurons in the control of cerebral blood flow (CBF) and cerebral energy metabolism. The data suggest several conclusions: 1. Arterial sympathetic innervation plays a role in the autoregulation of cerebral circulation. 2. The central adrenergic neurons have several functions: a) they enhance cerebral vascular tone by action on alpha receptor sites. b) They play an important role in the metabolic control of CBF. The proton-sensitive receptor sites on blood vessel walls require beta-adrenergic input in order to function. c) They influence metabolic rate of brain tissue by acting on beta-receptor sites on the cell membrane.
Gastrointestinal complication of high-dose corticosteroid therapy in acute cerebrovascular patients.
Authors: Ottonello G A , Primavera A
Published: June 2011

Corticosteroids are commonly used in the treatment of stroke, although their clinical effectiveness has not been established. Side effects, especially gastrointestinal complications, occur in patients with cerebral disease. A necroscopy study of 124 patients investigated the occurrence of gastrointestinal lesions in patients with acute stroke treated with high-dose of corticosteroids compared to untreated patients with stroke and to patients dying from non-vascular neurological diseases. A significant relationship between the use of steroids and gastrointestinal lesion in strokes is demonstrated.
Scanning electron microscopic study of endothelial cells of cerebral arteries from spontaneously hypertensive rats.
Authors: Hazama F , Ozaki T , Amano S
Published: June 2011

Endothelial cells of the cerebral arterial system in spontaneously hypertensive rats were investigated by scanning electronmicroscopy and found to show progressive changes such as increased microvilli, numerous plasmalemmal pits, enlargement of the cells and well-developed marginal folds. Regressive changes, such as balloon-like protrusions and crater-like cave-ins, were also observed. Platelet adhesion to the injured endothelial surface of cerebral arteries was frequent. The significance of these changes in the development of hypertensive cerebrovascular lesions is discussed.
The electrocardiogram in stroke: relationship to pathophysiological type and comparison with prior tracings.
Authors: Goldstein D S
Published: June 2011

The author reviewed electrocardiographic records of 150 patients with acute stroke and 150 age- and sex-matched controls, to assess the relative frequencies of ECG abnormalities among the pathophysiologic categories of stroke, and to distinguish new abnormalities at the time of the stroke from those noted on prior tracings. Of the 150 patients with stroke, 138 (92%) showed ECG abnormalities. The most common abnormalities were also changes from prior tracings: QT prolongation (68 patients, 45%), ischemic changes (59, 35%), U waves (42, 28%), tachycardia (42, 28%), and arrhythmias (41, 27%). Patients with cerebral embolus had a significantly increased frequency of atrial fibrillation (9 patients, 47%); and with subarachnoid hemorrhage an increased frequency of QT prolongation (20, 71%) and sinus arrhythmia (5, 18%). The frequencies of QT prolongation and ischemic changes related strongly to admission systolic pressure but not to mortality. Stroke patients had an increased frequency of pathologic Q waves (30 patients, 20%) and left ventricular hypertrophy (39, 26%), but these were not new findings at the time of the stroke. The results are consistent with an interaction of underlying hypertensive or atherosclerotic cardiovascular disease, sympathetic hyperactivity, and possibly myocardial necrosis, in producing ECG changes.
Transient ischemic attacks. Retrospective study of 150 cases of ischemic infarct in the territory of the middle cerebral artery.
Authors: Martí-Vilalta J L , Lopez-Pousa S , Grau J M , Barraquer L
Published: June 2011

Transient ischemic attacks (TIA) are episodes of abrupt beginning, consisting of subjective or objective neurological dysfunction of short duration, with complete recovery of neurological function in the course of 24 hours. With this definition, the authors carried out a retrospective study of 150 patients suffering from ischemic infarct in the brain in the territory of the middle cerebral artery. Thirty-eight percent of the patients had had TIAs before their cerebral infarct. The symptoms, in order of frequency, were motor, sensory deficits, alterations of speech and vision. Most of the patients had a definite cerebral infarct, occurring one month after the last TIA; the symptoms of both processes were remarkably similar. The authors studied the angiographic characteristics, pharmacological and toxic antecedents, and associated diseases in these patients. The study indicates that TIA may be the first manifestation of cerebral vascular disease.
Brain hemorrhage from intracranial tumor.
Authors: Little J R , Dial B , Bélanger G , Carpenter S
Published: June 2011

Brain hemorrhage from an intracranial tumor was encountered in 7 males and 6 females during a 4-year period. In 5 patients, hemorrhage was responsible for the first signs of a previously unsuspected neoplasm. The intracranial lesion was demonstrated by computed tomography (CT scanning) in each patient. Characteristic CT scan findings included: a neoplastic core (high or low density); small, multifocal clots usually at the margin of the tumor; and, surrounding, often extensive, edema. Enhancement of the tumor tissue with intravenous injection of 60% Hypaque was observed in the 8 patients so studied. The regions which were enhanced had a peripheral distribution corresponding to the site of hemorrhage. Microscopic examination demonstrated 7 glioblastoma multiforme, 1 oligodendroglioma, 4 metastatic carcinomas (including 1 each of bronchogenic carcinoma, melanoma, hypernephroma, and adrenal carcinoma), and 1 hemangiopericytoma. High-grade malignancy and extensive, abnormal vascularity appeared to be predisposing factors.
Role of catecholamine degradative enzymes and the adrenergic innervation in determining the cerebrovascular response to infused norepinephrine.
Authors: McCalden T A , Mendelow A D , Coull A , Scriven D R , Rosendorff C , Eidelman B H
Published: June 2011

Cerebral blood flow responses to intra-arterial infusion of norepinephrine (NE) at 0.55 microgram/kg/min and 1.1 microgram/kg/min were studied in 3 groups of baboons. The flow was measured by the intracarotid 133xenon clearance technique using a computer program to calculate flow (height over area--H/A) flow (initial slope--is) and cerebral metabolic utilization of oxygen (CMRO2). The normal response to NE was to increase flow without significant changes in CMRO2. Blockade of catechol-o-methyl transferase (COMT) produced vasoconstrictor responses to these same NE doses. Monoamine oxidase blockade abolished the normal vasodilation. Denervation of the cerebral circulation with intracisternal 6-hydroxydopamine produced vasoconstrictor responses with flow (H/A) but not with flow (is). It is concluded that the extra-neuronal COMT enzyme is important in limiting the access of blood-borne NE to cerebrovascular constrictor receptors.
Fluctuation of lipid peroxides and related enzyme activities at time of stroke in stroke-prone spontaneously hypertensive rats.
Authors: Tomita I , Sano M , Serizawa S , Ohta K , Katou M
Published: June 2011

The levels of lipid peroxides, determined as thiobarbituric acid reactive substances (TBARS), and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), were examined in the blood from stroke-prone spontaneously hypertensive rats (SHRSP), with and without cerebral lesions, and normotensive Wistar Kyoto (WK) rats. The levels of TBARS in the blood from healthy SHRSP were not significantly different from those of WK rats, while the values of SHRSP (male) with stroke were more than twice as high as those of healthy SHRSP. The activities of SOD and GSH-Px in stroke SHRSP were also statistically different from those of healthy SHRSP.
Topical prostacyclin (PGI2) inhibits platelet aggregation in pial venules of the mouse.
Authors: Rosenblum W I , El-Sabban F
Published: June 2011

Local application of prostacyclin (PGI2) to cerebral (pial) microvessels, inhibited the aggregation of platelets induced in the vessels by exposing them to a filtered mercury light source following intravenous sodium fluorescein. The inhibition was consistantly observed in venules rather than arterioles and was manifest by a lengthening of the time required for the noxious stimulus to produce an initial aggregate, and/or by a lengthening of the time required for enlarging aggregates to totally block the venule. The consistency of the inhibition diminished at doses below 100 microgram/ml. Inhibition was observed whether or not alcohol was used as the vehicle for PGI2 and whether or not the body temperature of the anesthetized mouse was permitted to fall.
Effect of phenoxybenzamine on cerebral blood flow and metabolism in the baboon during hemorrhagic shock.
Authors: Hamar J , Kovách A G , Reivich M , Nyáry I , Durity F
Published: June 2011

Experiments were performed on 2 groups of baboons anesthetized with Sernylan. One group served as control and the other was premedicated with 5 mg/kg phenoxybenzamine (PBZ). A 2-step hypovolemic shock model was used followed by retransfusion of the shed blood. Cerebral blood flow was measured by the 133Xe clearance method. Arterial and cerebral venous samples were taken and analyzed for blood gases as well as glucose and lactate content. The cerebral metabolic rates of oxygen, glucose, and lactate were calculated. In addition, the effect of CO2 inhalation was studied before shock was induced. PBZ produced no effect on either CBF or the flow response to CO2 prior to bleeding. PBZ pretreatment prevented the fall in cerebral blood flow and CMRO2 produced by systemic hypotension due to bleeding. Lactic acid showed no evidence of change either in production or uptake by the brain during the experimental procedure. The cerebral metabolic pathway of glucose, however, seemed to be affected by PBZ both before and during shock.
A simplified method for measuring regional blood flow.
Authors: Ames A , Fischer E G
Published: June 2011

A method of measuring regional blood flow (RBF) that is simple in procedure and calculations is described. By arresting flow promptly after a short pulse of diffusible tracer, it is feasible to equate the tracer retained in the tissue (Cfi) with that delivered by the blood. If the arterial pulse is characterized by its mean concentration (Ca) over a known duration (delta t), RBF can be estimated from Cif/Ca delta t). The error involved is relatively small and can be corrected for. If the amount of tracer injected is known, this procedure also provides an estimate of cardiac output and its fractional distribution to the regions sampled. The values obtained for RBF in 4 regions of brain were similar to those previously reported.
Critical appraisal of cerebral blood flow measured from brain stem and cerebellar regions after 133 Xe inhalation in humans.
Authors: Juge O , Meyer J S , Sakai F , Yamaguchi F , Yamamoto M , Shaw T
Published: June 2011

Validity of regional blood flow (rCBF) measurements recorded over the human posterior fossa after 133Xe inhalation was tested. Recording of counts from both brain stem and cerebellum (BSC) was reproducible and contamination by counts derived from surrounding anatomical structures was low and no greater than that found over hemispheres. BSC values were F1 = 99 +/- 19 ml/100g brain/min, F2 = 17 +/- 4 in reasonable agreement with data reported from experimental animals. BSC flow values showed significant correlation with the state of awareness as judged by clinical and EEG evaluation with lowest F1 values in semicoma and step increases in stupor, non-REM sleep, drowsiness, rest, activation, REM sleep and highest values during focal and generalized epileptic seizures.
Deterimental effect of prolonged hypothermia in cats and monkeys with and without regional cerebral ischemia.
Authors: Steen P A , Soule E H , Michenfelder J D
Published: June 2011

In a previous study occlusion of a middle cerebral artery (MCA) followed by 48 h of hypothermia (29 degrees) was lethal in 5 of 5 monkeys as compared to only 3 of 9 normothermic animals. The present study extended these observations in monkeys and cats with or without MCA occlusion. In monkeys MCA occlusion plus 48 h of hypothermia was consistently lethal. Without MCA occlusion of 2 of 3 monkeys survived, but were comatose the first 12 h post-hypothermia. In normothermic cats, MCA occlusion was lethal in only one of 5 animals whereas hypothermia was lethal in 20 of 21 cats with or without MCA occlusion. The detrimental effects of hypothermia were not favorably influenced either by hemodilution or by deliberate alterations in PaCO2. The effect of 48 h of hypothermia and rewarming on cerebral blood flow (CBF) and cerebral metabolites was evaluated in 6 normal monkeys. CBF was reduced 60 to 70 percent at 29 degrees C and returned to only a maximum of 50 percent of control with re-warming. Prior to re-warming distribution of CBF was inhomogeneous. Cerebral metabolites were borderline normal prior to re-warming but energy stores decreased while lactate increased with re-warming.
Cerebral arteritis in scleroderma.
Authors: Estey E , Lieberman A , Pinto R , Meltzer M , Ransohoff J
Published: June 2011

Central nervous system (CNS) involvement is rare in scleroderma unless there are concomitant abnormalities in renal or lung function or malignant hypertension. A 43-year-old woman with typical scleroderma developed subacute encephalopathy despite absence of the above abnormalities. Cerebral angiography demonstrated a focal arteritis. The patient improved while being given corticosteroids. We believe this case indicates that cerebral arteritis can occur in scleroderma.
Prostaglandin I2 and indomethacin prevent impairment of post-ischemic brain reperfusion in the dog.
Authors: Hallenbeck J M , Furlow T W
Published: June 2011

Twenty-seven heparinized dogs were exposed to 35 min of cerebrospinal fluid compression ischemia followed by 30 min of recirculation. The degree and distribution of post-ischemic reperfusion was then assessed by means of a 14C-antipyrine autoradiographic blood flow study. The animals were assigned to 5 groups by the administration of drugs as follows: 1) no additional drugs; 2) indomethacin 1.5 or 4 mg/kg prior to ischemia; 3) indomethacin 4 mg/kg 5 min after ischemia; 4) prostaglandin I2 (PGI2) infusion 30--180 ng/kg/min beginning 5 min after ischemia; and 5) indomethacin 4 mg/kg 5 min after ischemia plus PGI2 infusion 30--130 ng/kg/min beginning 5 min after ischemia. Animals receiving no additional drugs had relatively low post-ischemic blood flows with focal zones of greatly impaired reperfusion. Animals receiving either indomethacin or PGI2 after ischemia did not differ significantly from the no additional drug group. A significant enhancement of post-ischemic reperfusion occurred in animals receiving indomethacin prior to ischemia and those receiving the combination of indomethacin and PGI2 after ischemia. These observations implicate an imbalance in prostaglandin pathways at the blood-endothelial interface in the genesis of post-ischemic reflow impairment and suggest novel drug therapy for enhancing nutrient flow after ischemia.
Levels in stroke patients of CSF astroprotein, an astrocyte-specific cerebroprotein.
Authors: Hayakawa T , Ushio Y , Mori T , Arita N , Yoshimine T , Maeda Y , Shimizu K , Myoga A
Published: June 2011

Astroprotein (an astrocyte-specific cerebroprotein) levels in cerebrospinal fluid (CSF) were determined by radioimmunoassay in 47 stroke patients. (Astroprotein is immunologically identical to glial fibrillary acidic protein.) Astroprotein levels in CSF increased markedly in acute cases of intracerebral hemorrhage and slightly to moderately in some acute cases of subarachnoid hemorrhage and cerebral infarction. In intracerebral hemorrhage, CSF astroprotein levels in the acute stage of the ictus reflected the size of the lesion and were used to estimate the clinical outcome. In subarachnoid hemorrhage and cerebral infarction, CSF astroprotein levels were related to the general neurological state. Evidence obtained indicated that fundamentally different destructive and/or degenerative processes in the brain may be involved in intracerebral hemorrhage, subarachnoid hemorrhage and cerebral infarction and that determination of CSF astroprotein may have clinical significance in stroke patients.
Effects of hemorrhagic hypotension on the cerebral circulation. II. Electrocortical function.
Authors: Gregory P C , McGeorge A P , Fitch W , Graham D I , MacKenzie E T , Harper A M
Published: June 2011

The effects of graded hemorrhagic hypotension on electrocortical function was investigated in 12 cats anesthetized with alpha-chloralose. Cerebral function was assessed both in terms of spontaneous activity (EEG) and the somatosensory evoked response. No significant changes in the EEG trace or in the amplitude of the positive/negative waves of the primary evoked response were observed at mean arterial pressures of between 120 mm Hg and 40 mm Hg. At levels of systemic arterial pressure of less than 40 mm Hg cortical rhythms became slower as pressure was decreased and an isoelectric EEG was recorded in the pressure range 10--30 mm Hg. The earliest sign of any change in the amplitude of the primary evoked responses was observed at arterial pressures of approximately 35--40 mm Hg. Below this value the amplitude decreased with decreasing systemic pressure and became zero in the pressure range 15--25 mm Hg.
Effect of phenobarbital on cerebral energy state and metabolism. Enzymatic activities.
Authors: Benzi G , Agnoli A , Dagani F , Ruggieri S , Villa R F
Published: June 2011

The changes induced by phenobarbital in cerebral enzymatic activities of the Krebs' cycle (citrate synthase, malate dehydrogenase) and electron transfer chain (total NADH-cytochrome c reductase and cytochrome oxidase) were studied. In addition, the activity of lactate dehydrogenase of acetylcholine esterase and of glutamate dehydrogenase was also studied. These enzymatic activities were evaluated in the homogenate in toto and in a crude mitochondrial fraction from rat brain. The modifications in some of these activities indicate that several new metabolic situations occur in brain tissue after phenobarbital treatment.
Cerebral pathophysiology in hemorrhagic shock. Nuclide scan data, fluorescence microscopy, and anatomic correlations.
Authors: Bronshvag M M
Published: June 2011

Nineteen unanesthetized sheep were given Evans blue dye or radionuclide and then were incrementally bled into hemorrhagic shock (BP less than 50/25) by withdrawal of blood over a period of approximately one hour. Four sheep served as controls for histologic data. Static nuclide brain scans performed in 6 bled sheep demonstrated immediate uptake of the radionuclide. Fluroescence microscopic examination of brain tissue obtained at autopsy in bled sheep demonstrated dye uptake in the perivascular areas, but not in the neuropil. Electron microscopic examination of collateral cortical biopsy specimens showed swelling of perivascular astrocytic foot processes, but no endothelial abnormality. We feel that the uptake of radionuclide and dye-albumin complex by the perivascular astrocytes represents enhanced transendothelial transport rather than passage of molecules between endothelial cells. The significance of this presumably transient phenomenon is discussed.
Carotid artery velocity patterns in normal and stenotic vessels.
Authors: Blackshear W M , Phillips D J , Chikos P M , Harley J D , Thiele B L , Strandness D E
Published: June 2011

Duplex scanning provides real time B-mode images of the carotid bifurcation vessels along with a single gate pulsed Doppler flow velocity detector. By using the B-mode output of the duplex system to measure the Doppler angle and spectrum analysis to measure the frequency content of the Doppler signal, instantaneous flow velocity can be calculated. Mean velocity at peak systole was calculated retrospectively in 68 common (CCA) and internal (ICA) carotid arteries of 39 patients who had undergone prior angiography and prospectively in 30 arteries of 15 healthy young controls. The ratio of mean peak ICA velocity to mean peak CCA velocity at systole (VICA/VCCA) was below 0.8 in all 36 normal arteries and above 1.5 in all 21 high-grade stenoses of 60% or greater diameter reduction. Sixty-one percent of 41 vessels with less than 10 to 55% diameter reduction had a velocity ratio between 0.8 and 1.5. Only 10% of all ICA's with any stenotic lesion were incorrectly classified as normal. VICA/VCCA appears to be an accurate indicator of the degree of ICA stenosis.
Spontaneous bilateral recanalization in bilateral internal carotid artery occlusion.
Authors: Markwalder T M , Starrett R W , Mumenthaler M
Published: June 2011

The authors report a young woman with bilateral internal carotid artery occlusion shown by carotid angiography. There was spontaneous bilateral recanalization demonstrated radiographically. The possible causes, e.g. the intake of oral contraceptive drugs, a spontaneous intimal dissection and other etiological features are discussed and the literature is reviewed.
Temporal profile (clinical course) of acute vertebrobasilar system cerebral infarction.
Authors: Jones H R , Millikan C H , Sandok B A
Published: June 2011

Records of 37 consecutive patients with acute brain infarction from vertebrobasilar artery disease, admitted to the cerebrovascular hospital service within 36 hours of the onset of symptoms, were studied to define the temporal profile of clinical events during the first week of illness. A stable course with unchanged neurologic deficit was found in 11% (4 patients). Progressive improvement in symptoms occurred in 35% (13 patients). Progressive disability occurred in 43% (16 patients). A remitting-relapsing course was noted in 11% (4 patients). In these latter 2 groups, stabilization of the clinical course occurred in the majority with 48 hours after the initial symptom; however, definite changes continued to develop up to 96 hours in a significant number of patients. Mortality at the conclusion of the first week was 27% for the entire group. This was 2.5 times greater than the 10.6% previously reported for a group of 179 patients with acute brain infarction due to carotid system disease who were concomitantly studied.
Bilateral Nothnagel syndrome. Clinical and roentgenological observations.
Authors: Derakhshan I , Sabouri-Deylami M , Kaufman B
Published: June 2011

The clinical features of a patient with bilateral oculomotor palsy, ataxia, disturbance of memory, and hypokinesia are described. Pneumography and CT scanning showed dilation of the posterior portion of the third ventricle, indicating involvement of the postero-medial thalamic structures. The relation of this finding to the patient's amnesia and hypokinesia is briefly discussed. It is concluded that the patient suffered an infarction within the region served by penetrating branches which arise from the cephalad end of the basilar artery, probably including the mesencephalic artery.
Hemorrhage-induced cerebral vasoconstriction in dogs.
Authors: Pearce W J , D'Alecy L G
Published: June 2011

Cerebrovascular responses to a 20% volume hemorrhage were studied in chloralose-anesthetized dogs with the Doppler cerebral venous outflow method. Arterial PCO2, PO2, and pH were held constant by servocontrol of ventilation. The experimental results were divided into 2 groups as determined by the spontaneous responses of mean arterial pressure (MAP) to hemorrhage. In Group 1 (n = 11), steady state MAP decreased 25%, cerebral blood flow (CBF) decreased 15%, and cerebrovascular resistance (CVR) decreased 13% (autoregulatory vasodilatation). In group 2 (n = 23), MAP changed less than 10 mm Hg, CBF decreased 13%, and CVR increased 15%. The hemorrhage-induced cerebral vasoconstriction in Group 2 was characterized by the following: phenoxybenzamine (2 mg/kg i.v., n = 3) reduced post-hemorrhage CVR from 116% to 95% of prehemorrhage CVR (cCVR); phentolamine (2 mg/kg i.v., n = 5) reduced post-hemorrhage CVR from 114% to 91% of cCVR; and verified local anesthetization of both superior cervical ganglia (n = 5) reduced post-hemorrhage CVR from 116% to 94% of cCVR. Thus in Group 2, sympathetic vasoconstriction contributed approximately 5% of cCVR; following normotensive hemorrhage, it accounted for up to 20% of post-hemorrhage CVR. In combination with prevous studies, these data suggest that cerebrovascular responses to hemorrhage balance between autoregulatory vasodilatation and sympathetic vasoconstriction.
Spinal cord infarction: a highly reproducible stroke model.
Authors: Zivin J A , DeGirolami U
Published: June 2011

The study of focal central nervous system ischemia has been impeded by the lack of animal models that are both reproducible and simulate human ischemic strokes. To circumvent these problems, we have developed a rabbit spinal cord infarction model. Infarction of the caudal lumbar cord is produced by temporary occlusion of the abdominal aorta below the renal arteries. One hour of ischemia causes all of the animals to develop spinal cord infarctions in a highly reproducible pattern. These animals can be maintained alive for at least 2 weeks post-operatively. We believe that the tissue changes in spinal cord infarction are qualitatively similar to infarction of most areas of the central nervous system. This model has numerous features which make it particularly useful for neurochemical, neuropathological, and neurophysiological studies.
Physiological mechanisms controlling cerebral blood flow.
Authors: Mchedlishvili G
Published: June 2011

The major conceptions of cerebral blood flow (CBF) control developed in the 19th and 20th centuries are listed. The systems of CBF regulation are considered from the viewpoint of automatic control. In the classification of CBF regulation mechanisms, 4 types are identified. The effectors of CBF regulation, i.e. the specific arterial segments through which each type of regulation is accomplished, were found to be mainly the major arteries of the brain and the small pial arteries rather than the intracerebral arterioles. Review of controlling influences on these effectors of regulation, (myogenic, humoral and neurogenic), show that priority should be given to neurogenic mechanisms. Several criteria governing efficiency of CBF regulation are proposed. Review of interactions of different types of CBF regulation shows that there may be both synergistic and antagonistic relationships. Information about the processes is important for medical practice.
Evidence for greater susceptibility of isolated dog cerebral arteries to Ca antagonists than peripheral arteries.
Authors: Shimizu K , Ohta T , Toda N
Published: June 2011

In helically-cut strips of dog cerebral, coronary and mesenteric arteries, contracted with prostaglandin (PG) F2 alpha or K+, the addition of verapamil caused a dose-related relaxation. Verapamil-induced relaxations were greater in cerebral than in the other arteries when contracted with PGF2 alpha, but did not significantly differ in the arteries contracted with K+. Similar results were obtained with diltiazem and nifedipine. The contractile response to PGF2 alpha was attenuated by pretreatment with verapamil, the ateenuation being greater in cerebral than in mesenteric arteries. Nitroglycerin and sodium nitroprusside relaxed cerebral, coronary and mesenteric arteries contracted with PGF2 alpha to a similar extent. It may be concluded that dog cerebral arteries contracted with PGF2 alpha, one of endogenous vasospastic substances, are more susceptible to agents which interfere with the influx of Ca++ across cell membranes than coronary and mesenteric arteries; these agents may thus be of value in the treatment and prophylaxis of cerebral vasopasm.
Morphometric study on cerebral vessels in spontaneously hypertensive rats.
Authors: Nordborg C , Johansson B B
Published: June 2011

The ratio between media thickenss and lumen radius was determined in cerebral arterial vessels of 15- and 200-day-old spontaneously hypertensive (SHR) and normotensive rats (Kyoto Wistar and local Wistar rats). A modification of Furuyama's morphometrical method was used. There was a statistically significant increase of media/radius ratio among medium size and large vessels in 15-day-old SHR. Furthermore, the media cross section area and lumen radius was increased in the internal carotid arteries of young SHR. These early vascular aberrations could be caused by the slight increase of blood pressure at this age or be due to other genetically determined mechanisms in SHR. In 200-day-old SHR a significantly increased media/radius ratio was seen in arterial vessels with a radius less than 80 microns when compared to local Wistar rats but only in the smaller arterioles (r less than 20 microns) when compared to Kyoto Wistar rats. The present results offer a likely explantation for the increased cerebrovascular resistance during maximum vasodilatation in SHR.
Amaurosis fugax associated with ophthalmic artery stenosis: clinical simulation of carotid artery disease.
Authors: Weinberger J , Bender A N , Yang W C
Published: June 2011

A 72 year old woman complained of transient loss of vision in the left eye. She had undergone a left carotid endarterectomy 10 years previously. Reduced ophthalmic artery pressure was found on noninvasive carotid artery testing and cerebral angiography was performed. No lesion was evident in the carotid artery, but significant ophthalmic artery stenosis was identified. We report this case as showing the occurrence of amaurosis fugax in association with ophthalmic artery stenosis.
Value of the non-invasive cerebrovascular laboratory in diagnosis of extracranial carotid artery disease. An analysis of 159 studies in 157 patients.
Authors: Goran A , Moore G
Published: June 2011

Non-invasive vascular testing has proven to be an effective means of identifying patients with significant extracranial carotid artery disease. Such tests can yield valuable physiologic data in patients with TIAs and can identify patients with soft signs who may have significant carotid artery disease and who may be candidates for angiography. It may be an effective means of reducing the number of negative carotid angiograms.
Pial vascular reaction to intravenous dihydralazine in the cat.
Authors: Johansson B B , Auer L M , Trummer U G
Published: June 2011

The diameters of pial vessels in the cat were measured through a closed cranial window after i.v. injection of dihydralazine (250 microgram or 1 mg x kg-1). The intracranial pressure was recorded from a needle in the cisterna magna. In 7 cats given 1 mg x kg-1 dihydralazine, arterial vessels with a resting diameter of 72 +/- 24 micron (SD) dilated by 58 +/- 21% (p < 0.01), with no significant change seen in the veins. The intracranial pressure increased by 95 +/- 30%. The maximum increase in intracranial pressure and arterial diameter was observed before the blood pressure had reached its lowest level. The dilatation far exceeded the autoregulatory dilatation observed at corresponding pressure reductions induced by bleeding. It is concluded that dihydralazine dilates pial arterial vessels.
Role of central aminergic fibers in experimental cerebral ischemia in stroke-prone SHR. Relation to anesthetic effect.
Authors: Akiguchi I , Horie R , Yamori Y
Published: June 2011

Dopamine and norepinephrine fluorescence in the nucleus caudatus and putamen and cerebral cortex was markedly depleted along with rCBF reduction in symptomatic stroke-prone spontaneously hypertensive rats (SHRSP) with bilateral carotid artery ligation under light pentobarbital anesthesia. An accumulation of fluorescence at the intima of blood vessels, especially in the nucleus caudatus and putamen, was noted in some SHRSP under the same experimental conditions. These changes were hardly seen in deeply anesthetized SHRSP, as well as in normotensive Wistar-Kyoto (WK) rats. It may be possible, therefore, that released cerebral amines in acute brain ischemia accelerate the vasoconstriction and permeability of cerebral arteries, which further decreases the blood supply to these areas. Also, a barbiturate protective effect against the release of central dopamine and norepinephrine during acute brain ischemia was noted in deeply anesthetized SHRSP.
Hemodynamic response to profound hypoxia in intact rhesus monkeys.
Authors: Myers R E , Kopf G S , Mirvis D M
Published: June 2011

Respiring rhesus monkeys with 2.5 or 4.5% oxygen greatly decreased their cardiac contractility, stroke volume and blood pressure but altered their total peripheral vascular resistance only slightly and inconsistently. All monkeys exposed to 15 minutes and 2 of 4 exposed to 30 minutes of hypoxia recovered and survived without brain injury. Though all animals recovered full cardiovascular function immediately after they were reoxygenated, 2 respired with 4.5% oxygen for 30 minutes began showing declines in blood pressure after a delay of 1 to 2 hours and both subsequently died in shock. Their reductions in blood pressure were associated with reductions in cardiac contractility and stroke volume. The hypotension the animals exhibited both during hypoxia and during development of shock afterwards resulted from pump failure rather than a reduced vascular resistance or an inadequate venous return.
Prediction of hemispheric blood flow from carotid velocity measurements. A study with the Doppler and 133Xe inhalation techniques.
Authors: Risberg J , Smith P
Published: June 2011

Doppler carotid velocity determinations were related to hemispheric blood flow measurements by the 133Xe inhalation method in 28 patients with psychiatric disorders without arterial pathology and in 2 normal subjects. Results from 39 double determinations showed a product-moment correlation of 0.88 (p < 0.001) between right hemispheric blood flow and right internal carotid end-diastolic velocity. The correlation for the left side was slightly lower (r = 0.83), while the common carotid end-diastolic velocity showed a considerably lower correlation of 0.71 (rt) and 0.69 (lt) respectively. The peak-systolic velocity values (internal carotids) showed a less close relationship to hemispheric flow (r = 0.71 (rt) and r = 0.61 (lt)). It is concluded that a fairly accurate (15-20% maximum error) prediction of hemispheric blood flow from Doppler internal carotid end-diastolic velocity values is possible in patients without abnormalities in these arterial systems. The high correlations found, in spite of the fact that arterial diameters were not taken into account, are further proof of the accuracy and validity of both methods.
Transient appearance of "no-reflow" phenomenon in Mongolian gerbils.
Authors: Ito U , Ohno K , Yamaguchi T , Tomita H , Inaba Y , Kashima M
Published: June 2011

We investigated the existence of the "no-reflow" phenomenon in focal cerebral ischemia. Regional cerebral blood flow was studied in Mongolian gerbils perfused with a carbon-black particle suspension after cerebral ischemia prior to decapitation and compared with 14C-antipyrine autoradiographic images. The correlation between the occurrence of the "no-reflow" phenomenon and systemic arterial blood pressure change was also examined. We found that the phenomenon was transient in character and that its manifestation was related to the transient fall in arterial blood pressure observed immediately after clip release and with stagnation of venous blood flow. The phenomenon disappeared in animals in which the arterial blood pressure was artificially increased after clip release.