bluuebunny/crossref_metadata_2025 huggingface dataset:
A venous outflow method for measurement of rapid changes of the cerebral blood flow and oxygen consumption in the rat.
Authors: Nilsson B , Siesjö B K
Published: June 2011

A technique for continuous measurement of cerebral venous outflow in the rat is described. The method involves cannulation of one retroglenoid vein close to its exit from the skull, and diversion of cerebral venous blood through a closed extracorporal circuit with a drop recording device, the blood being returned to the central venous circulation via a catheter in the external jugular vein. Occlusion of the contralateral retroglenoid vein increases measured flow and minimizes extracerebral contamination of the diverted cerebral venous blood. The venous outflow system is not further isolated from cerebral or potential extracerebral collaterals. Thus, the mass of tissue drained cannot be exactly defined anatomically. However, the experiments involving changes of PP, arterial CO2 tension, and induction of epileptic seizure activity, and simultaneous indirect measurements with radioactive tracer technique, indicate that significant extracerebral contamination does not occur and that in short term measurements the venous outflow represents cerebral blood flow (CBF) in a constant mass of (dorsal and central, mainly forebrain) cerebral tissue. Measurement of arterial blood pressure and pressure in the cisterna magna allows calculation of cerebral perfusion pressure (PP). By simultaneous measurement of arterial and cerebral venous oxygen content changes in cerebral oxygen consumption (CMRO2) can be calculated. The method has been applied to document several situations of transient CBF and CMRO2 changes.
Regional cerebral blood flow during hypercapnia in the anesthetized rabbit.
Authors: Orr J A , DeSoignie R C , Wagerle L C , Fraser D B
Published: June 2011

These experiments were designed to test the hypothesis that increases in blood flow to the lower brainstem would be greater than forebrain regions during arterial hypercapnia. Total and regional cerebral blood flow (CBF) was measured via the tracer microsphere technique in seven anesthetized New Zealand white rabbits during normocapnia (arterial PCO2 congruent to 40 torr) and hypercapnia (arterial PCO2 congruent to 80 torr). During normocapnia average CBF was 0.77 ml/min/g, and regional measurements of blood flow indicated significantly greater flow to the cerebrum (0.86 ml/min/g) than either the medulla (0.52 ml/min/g) or the pons (0.49 ml/min/g). When arterial PCO2 was increased average CBF increased 113%, and a significant linear regression was calculated for arterial PCO2 vs CBF [CBF (ml/min/g) = 0.028 PCO2 (torr) - 0.502]. The distribution of blood flow within the brain was similar to normocapnia except that blood flow to the cerebellum was now greater than any other brain region (1.97 ml/min/g for the cerebellum compared to 1.66 ml/min/g for the cerebrum). Absolute increases in blood flow to the lower brainstem were equal to or less than other areas of the brain. We conclude that ponto-medullary blood flow does not increase disproportionate to other areas of the brain during hypercapnia, but some redistribution of CBF does occur in that cerebellar blood flow increased significantly more than the cerebrum, medulla, or pons.
A cerebrovascular accident with unusual features.
Authors: Gautier J C , Awada A , Loron P
Published: June 2011

A 64 y/o man experienced during 2 weeks TIA's or TIA's like episodes, once or twice a day, with or without contralateral pain in the head. CT Scans showed peculiar enhanced areas appended to the superior sagittal sinus. Angiography was refused. Twenty-seven months later during mild exertion a left frontal hematoma developed. Among frontal symptoms and signs laconism, abulia and a striking whispering were prominent. Angiography showed a dural arteriovenous fistula draining into cortical veins on the inner aspect of the left hemisphere. The fistula was successfully operated.
Transient aortic arch syndrome with dysphasia due to ergotism.
Authors: Feneley M P , Morgan J J , McGrath M A , Egan J D
Published: June 2011

A 55-year-old woman with an aortic arch syndrome of acute onset and dysphasia, resulting from the excessive administration of ergotamine tartrate suppositories, is described. Complete resolution of symptoms and return of upper limb and carotid artery pulses to normal occurred within four days of cessation of the ergot derivative. Lower limb involvement was conspicuously absent in this case.
Disruption of blood-brain barrier following bilateral carotid artery occlusion in spontaneously hypertensive rats. A quantitative study.
Authors: Sadoshima S , Fujishima M , Ogata J , Ibayashi S , Shiokawa O , Omae T
Published: June 2011

The present study was designed to clarify the relationship of cerebral blood flow (CBF) to blood-brain barrier (BBB) in the ischemic brains with or without recirculation, which were produced by clipping of both common carotid arteries in spontaneously hypertensive rats. CBF was measured by the hydrogen clearance method and BBB function was evaluated by the permeability of 131I-albumin and Evans blue dye. Cortical CBF was reduced from 48.8 +/- 9.5 to 4.0 +/- 1.2 ml/100 gm/min during 1 hr ischemia and further to 2.6 +/- 0.3 ml/100 gm/min during 3 hrs ischemia, while thalamic CBF was reduced much less from 50.0 +/- 3.6 to 17.9 +/- 6.5 ml/100 gm/min and to 17.5 +/- 11.0 ml/100 gm/min, respectively. There was no increase in permeability to protein tracers observed in such 1 hr or 3 hrs ischemic brain. Both cortical and thalamic CBF were markedly increased 2.5 to 6 fold of resting values at 5 min after recirculation in the 1 hr ischemic brain. In the 3 hrs ischemic brain, however, both CBF were only slightly increased but never restored to the resting level even at 30 min after recirculation. In such reperfused brains, exudation to Evans blue dye was observed in none of 16 animals with 1 hr ischemia, but in 18 of 23 with 3 hrs ischemia. Disruption of BBB was twice more frequent in the cortex (77.8%) than in either thalamus (33.3%) or hippocampus (33.3%). Permeability index of 131I-albumin (brain albumin/blood albumin) was significantly higher in the ischemic areas stained with blue dye (2.07 +/- 0.45%) than in non-ischemic control brain (0.10 +/- 0.01%).(ABSTRACT TRUNCATED AT 250 WORDS)
Cerebral amyloid angiopathy: incidence and complications in the aging brain. I. Cerebral hemorrhage.
Authors: Gilbert J J , Vinters H V
Published: June 2011

The clinical and pathologic findings in eleven patients with fatal cerebral hemorrhages related to cerebral amyloid angiopathy (CAA) are described. The hemorrhages were bihemispheric, though not necessarily of simultaneous onset in four patients, and favoured the fronto-parietal cortex and white matter in ten patients. Dissection into the subarachnoid space was common. Cerebrovascular lesions or cardiomegaly related to hypertension coexisted with those of CAA in three cases. Seven patients were not demented prior to the ictus. Ten of eleven brains contained abundant senile plaques and/or neurofibrillary tangles, whether or not the patient had been clinically demented. In the elderly, CAA is an important etiologic consideration for cerebral hemorrhage, especially if the hemorrhage occurs in a peripheral location in the brain and is superimposed on a history of dementia.
Doppler ultrasound assessment of the internal carotid artery following carotid endarterectomy.
Authors: Padayachee T S , Lewis R R , Yates A K , Gosling R G
Published: June 2011

Doppler-shifted ultrasound with spectral analysis was used to assess the internal carotid arteries of 48 patients who had undergone carotid endarterectomy (58 carotid endarterectomies). Three patients died in the immediate post-operative period, therefore 45 patients, who represented 54 endarterectomies, were assessed for up to six years following surgery (mean--thirty-four months). Ultrasound tests demonstrated total occlusion of the internal carotid artery in 7 patients within the first post-operative week. Sonograms from the supraorbital and common carotid arteries exhibit two peaks during cardiac systole (A and B). The post-operative A/B ratios were abnormal in 24 instances and these were associated with symptoms in seven. Of these 24, 7 developed severe disease in the internal carotid artery during the six year follow-up period; five were associated with symptoms. Post-operative A/B ratios were normal in 23 instances, 19 of which remained normal at follow-up. None of these nineteen developed symptoms. Only patients with abnormal post-operative A/B ratios subsequently developed severe occlusive disease in the internal carotid artery during the follow-up assessment. Thirty-eight patients underwent unilateral carotid endarterectomy, eight of whom had severe internal carotid artery disease at the contralateral bifurcation at the time of carotid endarterectomy. A further four patients developed severe occlusive disease in the contralateral internal carotid artery during the follow-up period, one of whom was symptomatic.
Enovid-induced exacerbation of the propensity for stroke in low protein fish diet-fed stroke-prone/SHR.
Authors: Wexler B C
Published: June 2011

Weanling, male and female, stroke-prone, spontaneously hypertensive rats (SP/SHR) were fed either a regular diet, a low protein diet derived from fish tissue + 1% saline drinking water, or the fish diet + 1% saline + daily injections of 0.1 mg Enovid/100 g bw/sc. After 48 days, the Enovid-treated animals developed acute and lethal strokes characterized by massive thrombonecrogenic lesions of the parietal lobe. The blood pressure of the Enovid-treated SP/SHR rose most acutely. The low protein fish diet was markedly catabolic and caused hyperlipidemia, hyperglycemia, elevated ACTH and beta-endorphin levels concomitant with reduced gonadotrophic function. Treatment with Enovid caused severe exacerbation of all of the foregoing changes. It is proposed that a low protein fish diet + 1% saline will accelerate the appearance of strokes in SP/SHR and that Enovid will enhance this effect through its anti-gonadotrophic activity and ability to stimulate increased pituitary-adrenal secretion.
Cerebrovascular response to hypoxia in young vs aged rats.
Authors: Hoffman W E , Albrecht R F , Miletich D J
Published: June 2011

Cerebrovascular responses of young and aged rats were tested to graded levels of hypoxia using a modification of the Levine ischemic-hypoxic rat model in which one carotid artery was ligated. Rats were anesthetized with 70% N2O, 30% O2 and cortical and subcortical cerebral blood flow (CBF) were measured with radioactive microspheres. CBF and cerebral cortical oxygen consumption (CMRO2) were measured under control conditions and during hypoxia with arterial oxygen content maintained at approximately 9, 5 and 3 ml . dl-1. CBF responses in cortical and subcortical tissues were similar between young and aged under control conditions and during moderate hypoxia (CaO2 = 9 ml . dl-1). Maximum cerebrovascular responses to severe hypoxia were greater in young than in aged rats and these trends were significant in both ligated and unligated cortical tissue (p less than 0.05). CMRO2 was maintained at control levels during moderate hypoxia but decreased significantly more in aged than in young rats when CaO2 was decreased to 3 ml . dl-1. These results suggest that baseline CBF and the sensitivity of cerebrovascular receptors to moderate hypoxia are similar in young vs aged rats but that maximum reactivity severe hypoxia is attenuated in aged subjects. CBF measured after one minute of hypoxia, before the induction of brain tissue acidosis, produced no significant change in the CBF response to hypoxia or in the difference between young and aged rats. Brain tissue pH changes do not appear to be the major factor for mediating CBF increases during hypoxia in young or aged rats, although it may interact with other mediators of the response.
Rapid freezing and frozen sectioning as a means of preserving brain vessel morphometric characteristics.
Authors: Hart M N , Hansen K E
Published: June 2011

A study was performed for the purpose of determining whether ordinary frozen sections of brain could preserve in vivo parenchymal arteriole morphometric characteristics. The results showed that flash-freezing followed by frozen sectioning is just as reliable a means of preserving brain arteriole morphometric characteristics as the time consuming process of flash-freezing followed by freeze substitution.
Cranial nerve paralysis following carotid endarterectomy.
Authors: Massey E W , Heyman A , Utley C , Haynes C , Fuchs J
Published: June 2011

During the past seven years 347 patients have been entered into a data bank at the Duke University Medical Center for evaluation of transient neurologic ischemia. One hundred fifty eight of these patients had carotid endarterectomies of whom 24 (15.1%) developed 26 (16.4%) peripheral cranial nerve palsies. Injury to the peripheral portion of the hypoglossal nerve was noted in 13 patients, to the cervical branch of the facial nerve in five and to the recurrent laryngeal nerve branch of the vagus in eight. Complete recovery of nerve function usually occurred within four months but residual deficit was present at one year in two patients with facial nerve and four with hypoglossal nerve involvement. Even though these complications of carotid endarterectomy are generally benign and transient, the frequency of occurrence can be reduced if careful attention is given to anatomic localization of the cranial nerves during surgery.
Assessment of regional cerebral blood flow (rCBF) in stroke using SPECT and N-isopropyl-(I-123)-p-iodoamphetamine (IMP).
Authors: Hill T C , Magistretti P L , Holman B L , Lee R G , O'Leary D H , Uren R F , Royal H D , Mayman C I , Kolodny G M , Clouse M E
Published: June 2011

In this study we assessed regional cerebral blood flow in patients with signs and symptoms of acute stroke using single-photon emission computed tomography (SPECT) and N-isopropyl I-123 p-iodoamphetamine (IMP). Twenty-five patients with acute cerebral infarction had both IMP brain perfusion studies and CT scans performed within one week of each other; 22 had positive and three had negative perfusion studies. Of the 22 patients who had positive perfusion studies, six had negative CT studies initially. In the 16 patients who had abnormal CT studies, eight of the studies depicted areas of edema that were smaller than the perfusion deficits noted on the IMP studies and eight had areas of edema that were approximately equal in size to the perfusion defect. Of the three patients with normal IMP studies, two had normal CT studies and one had a positive CT study showing a 3-mm lacunar infarction. Using eight control patients, mean count rates per tissue volume normalized for the injected dose was calculated. Similarly, the quantitative data from regions of interest in the stroke patients were calculated and compared to the control patients or to a normal region in the uninvolved hemisphere in the same patients. SPECT with IMP was used to assess regional brain perfusion in acute cerebral infarction. Perfusion abnormalities were seen in our patients when the CT scan was normal, and quantitative data could be used to approximate regional cerebral blood flow in these patients when compared to the normal patient population.
Hypoaggregability of washed platelets from stroke-prone spontaneously hypertensive rats (SHRSP).
Authors: Tomita T , Umegaki K , Hayashi E
Published: June 2011

The aggregation properties of washed SHRSP platelets were investigated in comparison with normotensive WKY platelets at prehypertensive (4 weeks), early hypertensive (11 weeks) and late hypertensive (17 weeks) ages in the absence of plasma factors. The number of platelets in SHRSP was markedly lower with the development of hypertension than that in WKY. The thrombin- and collagen-induced aggregation was markedly reduced in the platelets from 11 and 17 week old SHRSP compared with that of age-matched WKY, whereas the degree of platelet aggregation in 4 week old SHRSP showed a tendency to be even greater than that in WKY. The changes in blood pressure and platelet aggregability were correlated inversely. ADP did not induce aggregation in the same system used for thrombin and collagen stimulation but in another system it aggregated washed rat platelets. Aggregation responses to ADP and ionophore A23187 were also significantly lower in 14 week old SHRSP platelets than age-matched WKY platelets. Together with other evidence, these results suggest that defective Ca2+ function, rather than the presence of exhausted platelets, is responsible for hypoaggregability in SHRSP platelets.
Responses of isolated canine basilar artery and human platelet to chlorpromazine and amitriptyline.
Authors: Sukenaga A , Tani E , Fukumori T , Maeda Y
Published: June 2011

Sustained contraction of isolated canine basilar artery was induced by addition of prostaglandin F2 alpha, prostaglandin E2, hemoglobin-containing solution, or serum. Human platelet aggregation was induced by 1.0 microM adenosine diphosphate. The sustained contraction of basilar artery and the aggregation of platelet, particularly its secondary aggregation, were inhibited in a dose-dependent manner by addition of chlorpromazine or amitriptyline; calmodulin antagonist. The molar concentrations at 50% inhibition by chlorpromazine or amitriptyline were 5.9 to 7.7 microM or 28 to 39 microM for the contraction of basilar artery and 57 microM or 111 microM for the secondary aggregation of platelet. The results were discussed mainly on the basis of interaction of psychotropic drugs and Ca2+, calmodulin-dependent enzymes, particularly myosin light chain phosphorylation.
Hypoxia induced preferential ketone utilization by rat brain slices.
Authors: Kirsch J R , D'Alecy L G
Published: June 2011

When exposed to hypoxia, intact mice, with elevated blood ketones, live longer than mice with normal blood ketones. To evaluate a possible mechanism responsible for this phenomenon a rat brain slice preparation was used to determine if brain tissue would utilize glucose or ketones preferentially during exposure to reduced oxygen. Reducing available oxygen in the incubation medium from 95%, in steps, to 5% produced the expected gradual reduction in the carbon dioxide formation from glucose. In contrast, reducing the oxygen level to 40 and 20% resulted in a statistically significant stimulation of the production of carbon dioxide from the ketone beta-hydroxybutyrate. At very low oxygen levels carbon dioxide production from either substrate was reduced. These results are consistent with the hypothesis that ketones can be used in addition to glucose as a substrate for brain energy production even during reduced oxygen availability. If the increase in carbon dioxide production from ketones can be equated with an increase in energy production from this supplemental substrate then ketones may be therapeutically useful in avoiding the collapse of brain function during moderate hypoxia.
Protective action by methylprednisolone, allopurinol and indomethacin against stroke-induced damage to adenylate cyclase in gerbil cerebral cortex.
Authors: Taylor M D , Palmer G C , Callahan A S
Published: June 2011

Adenylate cyclase activity was investigated in either homogenate or particulate fractions from the frontal cerebral cortex of the gerbil following five experimental conditions of bilateral ischemia. After periods of 15 min ischemia, 15 min ischemia plus 15 min of recirculation or 60 min ischemia the enzyme generally displayed enhanced responses to GTP, norepinephrine (NE), dopamine (DA), NE + GTP and DA + GTP. Pretreatment of the gerbils with methylprednisolone, allopurinol or indomethacin did not significantly influence the outcome of these findings. When the animals were subjected to 60 min ischemia plus 15 min of reflow, enzyme responses to the stimulatory agents including forskolin and NaF were all reduced. Pretreatment with methylprednisolone, allopurinol or indomethacin prevented the damage to adenylate cyclase in the 60 min ischemia plus 15 min reflow animals. When animals were made ischemic for 15 min followed by one week of recovery, enzyme sensitivity to GTP, calmodulin-Ca++, NE, combinations thereof and forskolin were reduced in only the particulate fractions. Enzyme damage was reversed following methylprednisolone. Enzyme damage may result from generation of free radicals during reflow and drugs that either inhibit synthesis pathways generating free radicals, stabilize cell membranes or act as free radical scavengers may be therapeutically beneficial under specific conditions of stroke.
Regional cerebral blood flow and oxygen consumption of the canine brain during hemorrhagic hypotension.
Authors: Chen R Y , Fan F C , Schuessler G B , Simchon S , Kim S , Chien S
Published: June 2011

The sequential changes in systemic and cerebral hemodynamics, systemic and cerebral oxygen transport and consumption rates, and the regional blood flows (measured with 15 micron microspheres) to the cortical and subcortical brain tissues were determined in nine dogs subjected to graded hemorrhage (10 ml/kg X 4 at 15 min intervals). As hemorrhage progressed, both mean arterial pressure and cardiac output decreased progressively. In contrast to the systemic circulation, the mean cerebral blood flow (mCBF) was well maintained by cerebral vasodilation and the cerebral O2 consumption rate (CMRO2) increased during the first three stages of hemorrhage. At 40 ml/kg of hemorrhage, there were significant reduction in mCBF and CMRO2 despite the increase in O2 extraction, suggesting the occurrence of cerebral hypoxia and decompensation of the cerebral circulation. There were remarkable regional variations in the responses of regional cerebral blood flows (rCBF) to hypovolemia, resulting in a significant redistribution of cerebral blood flow. The fractions of cardiac output supplying the diencephalon (thalamus and hypothalamus), the brain stem (pons and medulla oblongata) and the cervical spinal cord increased after hemorrhage up to 40 ml/kg. The redistribution of rCBF favors those areas where neurons related to cardiovascular control are located. These findings have significant implications relating to hemodynamic regulation during hemorrhagic hypotension.
Doppler power frequency spectrum analysis in the diagnosis of carotid artery disease.
Authors: Krause H , Segard M , Carey P , Bernstein E F , Fronek A
Published: June 2011

Power Frequency Spectral Analysis (PFSA) which evaluates the power of the frequency components at a selected interval, was applied in this preliminary study using a 5MHz Doppler continuous wave flow velocity meter and a modified Edwards Spectraview 500 analyzer. PFSA was used to study the common, internal and external carotid arteries of ten young adult control subjects and 31 patients with angiographically documented carotid bifurcation lesions. Two useful indices are described: (1) the frequency band width at 50% of maximum power (f50%) and (2) the highest frequency recorded (fmax). An f50% wider than 1900 Hz (corresponding to spectrum broadening) identified stenoses as low as a 15% diameter reduction. An fmax higher than 6500 Hz practically always indicated a 50% or greater diameter reduction. Eighty two percent of stenoses with 11-25% diameter reduction were detected, as were 95% of stenoses from 36-50%. All stenoses from 51-99% were identified.
Italian multicenter study on reversible cerebral ischemic attacks: III--Influence of age and risk factors on cerebrovascular atherosclerosis.
Authors: Candelise L , Bianchi F , Galligoni F , Albanese V , Bonelli G , Bozzao L , Inzitari D , Mariani F , Rasura M , Rognoni F
Published: June 2011

The influence of age and other risk factors (history of hypertension and diabetes, cigarette smoking, dyslipidemia) on cerebral atherosclerosis was studied in 462 patients with RIA who had cerebral angiography. The degree of atherosclerosis was quantified using extracranial and intracranial cerebrovascular scores (ECS, ICS) based on the number and severity of the lesion in 11 extracranial and 21 intracranial arterial segments. Thirty-six percent of the patients under age 45 had a normal angiogram compared with 17% of the patients over 45. In the subgroup of patients with abnormal angiogram the mean ECS and ICS vascular scores were not significantly different in the two age groups. Cigarette smoking was the only risk factor to show a strong association with the extracranial score, and it was independent of the effect of age and other risk factors.
Subarachnoid hemorrhage in an isolated population. Incidence on the Faroes during the period 1962-1975.
Authors: Joensen P
Published: June 2011

In a retrospective study of a 14-year period (1962-1975) the annual incidence of subarachnoid hemorrhage (SAH) was found to be 7.4 per 100,000 in an isolated population of about 40,000. The age-specific incidences in the age groups from 15-25 to 60 years are on the same level as found in Sweden, Rochester USA, England, and Iceland, but lower than the findings in Finland. The age-specific incidence among persons over 60 years of age was far lower than in Sweden, Rochester USA, and Finland. The possible causes of the lower incidence in all age groups than reported in the above-mentioned studies are discussed. Forty patients had a history of SAH. Two months after the episode 38% had died and at the end of 5 years 53%. The recurrence rate at 5 years was 24%.
Distribution of the blood flow supplied by the vertebral artery in humans as assessed by emission CT.
Authors: Taki W , Handa H , Higa T , Tanada S , Fukuyama H , Fujita T , Yonekawa Y , Kameyama M , Torizuka K
Published: June 2011

Though unilateral blood distribution of the vertebral artery has not been studied in humans, it is significant when considering the ischemic events especially embolic occlusion in vertebrobasilar system. To clarify the blood distribution, Krypton-81m was continuously infused into the vertebral arteries of 10 patients. Radioactivity was recorded by a rotating gamma camera. The perfusion images, reconstructed by computer in the transaxial plane, were classified according to whether the distribution was equal, or predominantly unilateral. Overlapping of blood supply from each vertebral artery was studied. In addition, the perfusion from one of the vertebral arteries revealed four distribution patterns with respect to laterality. A) ipsilateral; B) contralateral; C) bilateral; D) mosaic. Images obtained following perfusion of the vertebral artery show less uniformity compared to that of the internal carotid artery, suggesting a complicated vascular supply of the vertebral basilar territory. This complex distribution can be classified by the use of continuous infusion of Krypton-81m.
Response of local blood flow in the caudate nucleus of the cat to intraventricular administration of carbachol.
Authors: De Ley G , Weyne J , Demeester G , Leusen I
Published: June 2011

The effect of perfusion of the cerebral ventricles with artificial cerebrospinal fluid containing carbachol on the blood flow in the caudate nucleus of the cat and the possibility to inhibit this effect by anticholinergic drugs was studied by means of the hydrogen clearance technique. After a control period during which both lateral ventricles were perfused with artificial CSF of identical composition, the drug under study was added on one side (experimental side) while the other side continued to be perfused with the control artificial CSF (control side). The blood flow on the experimental side and on the control side were compared. A dose dependent response to carbachol was observed. Lower concentrations of carbachol (10(-6) up to 10(-4)M) caused vasodilatation whereas high concentrations (10(-3)M) caused local vasoconstriction. The increase in the local blood flow caused by the low carbachol concentrations was reduced by both atropine (10(-5)M) and hexamethonium (10(-3)M). The fall in CBF observed with the high carbachol concentration was prevented by atropine (10(-5)M). It may be concluded that low, physiologically more meaningful, carbachol concentrations cause a local vasodilatation due to interaction with both muscarinic and nicotinic receptors.
PH changes on the surface of brain and in cisternal fluid in dogs in cardiac arrest.
Authors: Javaheri S , Clendening A , Papadakis N , Brody J S
Published: June 2011

We measured brain surface pH and cisternal cerebrospinal fluid (CSF) acid-base variables in Na-pentobarbital anesthetized dogs during KCl induced cardiac arrest. Electrocardiographically, an agonal rhythm occurred within seconds, presumably resulting in rapid fall in cerebral blood flow. The mean arterial blood pressure fell from 125 +/- 22 (mean +/- 1 SD) to 35 +/- 28 mm Hg at 30 seconds and to 19 +/- 3 mm Hg at 60 seconds after KCl injection. The mean brain surface pH (n = 8) dropped abruptly from 7.30 to 6.80 within 3 minutes after induction of cardiac arrest. Changes in cisternal CSF pH, however, occurred slowly with the mean pH falling from 7.33 to 7.27 at 4 minutes and to 6.99 at 10 minutes after induction of cardiac arrest. The fall in cisternal CSF pH was due to a rise in CSF concentration of organic acids as well as a rise in CSF Pco2; the mean cisternal CSF [HCO3-] fell 3.6 mEq/l while the mean cisternal CSF lactate concentration and the mean CSF Pco2 rose, respectively, 2.1 mEq/l and 37.8 mm Hg 10 minutes after induction of cardiac arrest. We conclude that during acute ischemic anoxia gross pH disequilibria develop between brain extracellular fluid and cisternal CSF; analyses of the latter fluid provide unreliable information about brain metabolic status and its acid-base balance even up to ten minutes after induction of cardiac arrest.
A physical model for the formation of evaginations: a prospective precursor to the creation of saccular aneurysms.
Authors: Campbell G J , Roach M R
Published: June 2011

The actual spatial geometry of separate regions of normal and enlarged fenestrations from the internal elastic lamina of human cerebral arteries have been replicated in sheets of latex rubber from scanning electron microscope (SEM) photomicrographs. Geometrical models which assume a constant diameter for the fenestrations, a constant ligament efficiency for the regions of fenestrations and a uniform array of rows and columns have also been created in sheets of latex rubber. The stress (load per unit of cross-sectional area) and strain (percent elongation) were computed for each of the samples during uniaxial stretching. The elongation of the sample representing the region of enlarged fenestrations increased an average of 47% compared to the similar representation of normal fenestrations, at the same increments of stress. This suggests that regions of enlarged fenestrations would form a bulge, indicative of an evagination of the internal elastic lamina. The model configurations demonstrate very similar stress/strain characteristics to the replications. This finding justified the use of the modelling technique using equivalent ligament efficiencies, to represent the actual spatial geometry. During elongation, the average area of the enlarged fenestrations increased at a rate which was an order of magnitude greater than the normal fenestrations. Since a number of observations associated with the development of intracranial saccular aneurysms can be correlated to a region of enlarged fenestrations, the region of enlarged fenestrations may be a defect in the internal elastic lamina which could play a prominent role in the development of intracranial saccular aneurysms.
The protective effect of combined administration of anti-oxidants and perfluorochemicals on cerebral ischemia.
Authors: Suzuki J , Fujimoto S , Mizoi K , Oba M
Published: June 2011

We previously published results of investigations which indicated that the combination of mannitol, which acts as a free radical scavenger, and perfluorochemicals (PFC), which have a strong oxygen-carrying capacity, can be therapeutic in cases of brain infarction. The present experiment tested the hypothesis that the effectiveness of such treatment could be increased by an optimal combination of such scavengers and other chemicals. Fifty-two dogs were used, employing the "canine model of a completely ischemic brain regulated with the perfusion method." A total of six drugs with free radical scavenger capacities were tested: mannitol, vitamin E, vitamin C, Nizofenone (Y-9197), dexamethasone (DEXA) and suloctidil (MY-103). These drugs were administered intravenously 15 minutes prior to the production of ischemia, when cerebral blood flow was reduced to one-tenth its normal volume. After one hour, recirculation was allowed and the recovery of electrical activity of the brain observed for three hours. Judged by the degree of recovery of brain electrical activity, five drugs were considered to have protective effect against brain ischemia: mannitol, vitamin E, MY-103, DEXA and Y-9197. Among these five drugs, mannitol, vitamin E and DEXA are known to be safe and easily used clinically. The combined administration of these three drugs, together with PFC, was also investigated. It was found that the speed and degree of recovery of brain electrical activity were greater when these drugs were given together than when one was administered alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Pial arterial pressure in cats following middle cerebral artery occlusion. II. Relationship to regional disturbance of energy metabolism.
Authors: Paschen W , Shima T , Hossmann K A
Published: June 2011

Focal cerebral ischemia was produced in 16 cats by occluding the left middle cerebral artery (MCA) for 120 min. Cortical blood flow and pial artery pressure were determined prior to vascular occlusion and after 15, 60 and 120 min. At the end of the experiments (after 120 min MCA occlusion) heads were frozen in situ with liquid nitrogen. Cooled brains were cut into 0.5 cm thick slices. From these slices twenty-micron sections passing through the territory of the MCA were prepared in a cryostat and used in the pictorial presentation of glucose and ATP. NADH-fluorescence was recorded from the tissue slice, immersed in liquid nitrogen. In addition, tissue samples were taken from regions of interest and used for quantitative determination of biochemical substrates. In all but two animals permanent MCA occlusion led to disturbances in the energy-producing metabolism, as indicated by reduction in glucose and ATP, and increase in lactate. The regions exhibiting bright NADH-fluorescence were much smaller than those in which ATP was absent. In 6 animals NADH-fluorescence was not increased but even decreased in areas with disturbed energy-producing metabolism. A close correlation was obtained after comparing cortical blood flow measured 15 min after MCA occlusion with the area of ATP-depletion at the end of the experiments. However, the size of ATP-depletion did not correlate with flow measured 60 or 120 min after MCA occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)
Regional blood flow in canine brain during nicotine infusion: pentobarbital vs. chloralose anesthesia.
Authors: Bedran de Castro M T , Crystal G J , Downey H F , Bashour F A
Published: June 2011

We compared vasoactive effects of intravenous nicotine (36 micrograms/kg/min) in regional cerebral circulations under pentobarbital and chloralose anesthesia. Experiments were conducted in three groups of dogs: Group I, pentobarbital anesthesia with fixed ventilation; Group II, chloralose anesthesia with fixed ventilation; Group III, chloralose anesthesia with free breathing. Values for regional cerebral blood flow measured with 15 mu radioactive microspheres were used to compute regional cerebral vascular resistance (rCBR). In Group I, nicotine had no effect on rCVR in cerebral cortex, and it increased significantly rCVR in cerebellum (+17%), pons (+13%), medulla (+23%), and spinal cord (+19%). Using chloralose instead of pentobarbital in dogs with fixed ventilation (Group II), caused a significant reduction in rCVR in the cerebral cortex during nicotine, although it did not alter significantly nicotine-induced changes in rCVR in other regions of the brain. Hypocapnic alkalosis during nicotine-induced hyperventilation (Group III) resulted in significant increases in rCVR in all regions of the brain; however, the increases in rCVR in non-cortical regions more than doubled those in the cerebral cortex. The present results indicate: Nicotine-induced vasodilation in cerebral cortex was blunted by pentobarbital anesthesia. Nicotine-induced vasodilation in cerebral cortex under chloralose anesthesia was sufficient to nullify in part the potent vasoconstrictor effect of hypocapnic alkalosis.
Trends in stomach cancer and stroke in Finland. Comparison to northwest Europe and USA.
Authors: Tuomilehto J , Geboers J , Joossens J V , Salonen J T , Tanskanen A
Published: June 2011

The mortality rates of stomach cancer and stroke were found to decrease in a similar way over a given time in different countries. The same phenomenon can be observed in Finland for both sexes. Salt is suggested to be the linking factor in the stroke-stomach cancer relationship. Recent studies indicate that salt intake in Finland is very high. Actual salt consumption levels are in Finland as high as they were in Belgium 15 years ago. The same observations can be made for cerebrovascular and stomach cancer mortality, making the salt hypothesis plausible. In contrast from 1972-73 on stroke mortality decreases faster than stomach cancer mortality. This could be observed in other western countries: USA, Austria, England and Wales, Belgium, West Germany, etc. The steeper decline may be the consequence of mass drug treatment of hypertension which started in Finland during the early years of 1970's, and also the consequence of changes in dietary habits, especially in fat intake in Finland.
The effect of Fluosol-DA on oxygen availability in focal cerebral ischemia.
Authors: Sutherland G R , Farrar J K , Peerless S J
Published: June 2011

The effects of Fluosol-DA 35% (15 ml/Kg, IV) on cortical oxygen availability (O2a), a relative measurement of cortical oxygen tension, were examined in 16 cats subjected to temporary middle cerebral artery (MCA) occlusion. The cats were divided equally into control and treatment groups and half of each group underwent MCA occlusion at room air ventilation and the other half at 100% O2 ventilation. Prior to occlusion, Fluosol had no effect on arterial PO2 or cortical O2a at normoxia, however, there was a significant increase in both arterial PO2 and O2a following 100% O2 ventilation (pre vs post Fluosol). In an additional 5 cats, Fluosol resulted in a transient decrease in blood oxygen content due to hemodilution. Concurrent to this decrease, cerebral blood flow increased substantially resulting in a net increase in oxygen delivery. Within ipsilateral hemispheres, MCA occlusion resulted in decreased O2a to levels below the pre-occlusion normoxic values in all animals except those treated with Fluosol and ventilated with 100% O2. During reperfusion, O2a immediately recovered to hyperoxic levels in the Fluosol 100% O2 animals, whereas in the other three groups, O2a returned more gradually towards the pre-occlusion value. Since neither 100% O2 alone nor Fluosol plus room air ventilation significantly improved O2a in the ischemic cortex, we conclude that increased delivery of plasma plus Fluosol bound oxygen was responsible for the observed improvements in O2a following MCA occlusion.
Relationship between longitudinal changes in blood pressure and stroke incidence.
Authors: Shimizu Y , Kato H , Lin C H , Kodama K , Peterson A V , Prentice R L
Published: June 2011

The relationship of changes in blood pressure with time to stroke incidence was examined on members of the Adult Health Study sample who have participated in biennial clinical examinations at the Radiation Effects Research Foundation since their inception in 1958. The regression coefficient of blood pressure regressed on time (the increase in blood pressure per cycle) was used as an index of the change in blood pressure with time. Cox's regression analysis, a technique which is suitable for follow-up studies was used. The data suggest that a single blood pressure measurement is not sufficient for predicting risk; the accumulated value or average over a period of time should be considered for this purpose. In addition to the actual blood pressure, the increase in blood pressure with time is a risk factor, particularly for cerebral hemorrhage. Cerebral hemorrhage was more strongly related to diastolic than to systolic blood pressure, while cerebral infarction appeared to be more strongly related to systolic than to diastolic blood pressure.
Correlation between brain surface potassium and glucose utilization after bilateral cerebral ischemia in the gerbil.
Authors: Choki J , Greenberg J , Sclarsky D , Reivich M
Published: June 2011

The correlation between cerebral glucose utilization and brain surface potassium concentration (BS-K+) was studied during reperfusion following bilateral cerebral ischemia in the gerbil. Cerebral glucose utilization rate was measured by the 14C-2-deoxyglucose method and BS-K+ was continuously monitored by a potassium sensitive membrane electrode. BS-K+ increased from 3.0 +/- 0.6 mM (mean +/- S.D.) before ischemia to 58.7 +/- 17.3 mM 30 minutes after the occlusion of both common carotid arteries. The rate of decline of BS-K+ after release of occlusion differed between animals. Glucose utilization rate in the cerebral cortex immediately under the potassium electrode was low but homogeneous in 7 animals while in 5 animals the metabolic pattern was heterogeneous with areas of both low and high glucose metabolism. The former animals exhibited a fast recovery of potassium flux while the latter animals showed a slow recovery. Glucose utilization rate and potassium half recovery time were linearly correlated. These studies suggest that the reason that potassium flux may not recover rapidly in postischemic brain tissue is due to the lack of sufficient energy for a rapid re-establishment of the ion gradient across the cell due to the inefficient energy production of anaerobic glycolysis.
Disablement and quality of life after stroke.
Authors: Ahlsiö B , Britton M , Murray V , Theorell T
Published: June 2011

This study concerns the quality of life of patients after stroke and how this is influenced by disablement and emotional factors. Ninety-six consecutive patients of mean age 71 years were followed for two years. At the end of that time 23% had experienced a recurrence of stroke and 27% were deceased. Of the survivors 76% were independent as regards activities of daily life (ADL) and lived in their own homes. Age as well as initial function were prognostically important factors. Patients who could participate in interviews marked on a visual analogue scale their evaluation of quality of life before and after stroke. Most of them had experienced a decrease and no improvement was observed during the two years. The deterioration was more pronounced in ADL dependent patients than among the independent. However, depression and anxiety were found to be of similar importance for quality of life as was physical disablement. These findings call for a greater emphasis on psychological support in the care of post stroke patients. The visual analogue scale can be a useful tool for detecting special needs.
Cerebral infarction secondary to unsuspected intracranial fibromuscular dysplasia following bypass of aortic coarctation.
Authors: Malloy D S , Sangalang V E , Fraser G M
Published: June 2011

Fibromuscular dysplasia (FMD) is an uncommon finding in the cerebral circulation. We present a case of unsuspected intracranial FMD in a patient dying from a large cerebral infarct following a bypass operation for coarctation of the aorta. The need for recognizing the possible co-existence of these two lesions is emphasized.
The effects of calcium antagonism on the epicerebral circulation in early vasospasm.
Authors: Leblanc R , Feindel W , Yamamoto L Y , Milton J G , Frojmovic M M , Hodge C P
Published: June 2011

We have studied the effects of the calcium antagonist verapamil on the epicerebral arteriovenous transit time and regional epicerebral circulation of dogs by direct measurement of arterial diameters, fluorescein angiography, and krypton-85 regional epicerebral blood flow analysis. A large craniectomy was performed and vasoconstriction was induced by the subarachnoid injection of human platelet-rich plasma (PRP) pretreated with 25 mu M of ADP to cause maximum aggregation. Once vasoconstriction was established, verapamil (0.1 mg/kg) was topically applied to the perforated arachnoid. The PRP-ADP produced a mean decrease in the arterial diameters of 38.2 +/- 1.6% (p less than 0.01) at 10 minutes after its injection and verapamil produced a mean dilatation of 19.5 +/- 2.5% (p less than 0.01), compared to control values. Regional epicerebral blood flow was 54.9 +/- 3.4 ml/100 g/min in the control state, 34.8 +/- 3.2 ml/100 g/min (p less than 0.01) during vasospasm, and 78.2 +/- 4.5 ml/100 g/min (p less than 0.01) after verapamil. Fluorescein angiography, after verapamil, demonstrated a mean acceleration of the arteriovenous circulation time of 4.5 +/- 0.8 seconds (p less than 0.01) compared to the spasm value. We concluded that the topical application of verapamil can dilate previously constricted cortical arteries and that this dilatation is associated with acceleration of the epicerebral transit time and increased cerebral blood flow.
The performance of endarterectomy for disease of the extracranial arteries of the head.
Authors: Dyken M L , Pokras R
Published: June 2011

Data from the National Hospital Discharge Survey, the Veterans Administration Hospitals and Armed Forces Hospitals were reviewed to estimate the number of endarterectomies of extracranial vessels of head and neck performed in the United States. The number increased from around 15,000 in 1971 to around 85,000 in 1982. An estimated 2.8% of those operated in non-federal hospitals were discharged dead.
Review of a community hospital experience with carotid endarterectomy.
Authors: Slavish L G , Nicholas G G , Gee W
Published: June 2011

Carotid endarterectomy was performed 743 times during 56 months in a community hospital by 24 surgeons. The mortality rate was 2.7% and permanent stroke occurred in 1.8%. Temporary postoperative neurologic deficit occurred in 3.5%. The frequency with which the surgeon performed the procedure did not appear significant in the incidence of postoperative morbidity and mortality.
Outcome of surgical treatment of 110 patients with transient ischemic attack.
Authors: Muuronen A
Published: June 2011

Between 1980 and 1982, 227 consecutive patients with transient ischemic attack (TIA) or ischemic brain infarction (IBI) were evaluated as possible candidates for carotid surgery in the Department of Neurology, University of Helsinki. One hundred and ten patients (mean age 58, range 41-72 years) were selected for surgery; 82 of them had had TIA and 28 IBI as the presenting symptom. After a total of 128 operations (84 unilateral and 18 bilateral endarterectomies, and 8 arterial reconstructions), 16 patients (14.5%) developed neurological deficits. In 7 patients (6.4%), the deficit was severe and 4 of them (3.6%) died within the first four days after surgery. Ten patients had occlusion of the contralateral internal carotid artery and/or severe hypertension. Five of them suffered ischemic brain infarction after the operation and two died. Operation on an occluded internal carotid artery in 7 patients was complicated by hemiparesis in two patients, one of whom died. Patients with surgical complications more often had severe hypertension (p less than .001), total occlusion of the contralateral internal carotid artery, (n.s.) and severe angiographic changes (n.s.) compared with patients without complications. During the follow-up the annual rate for IBI was 3.3% and for acute myocardial infarction (AMI) 4.4%. Vascular death occurred with a frequency of 1.7% per year. The results emphasize that patients with TIA or IBI should be carefully evaluated before recommending surgical treatment for prevention of threatened stroke. Patients with severe risk factors may fare better on medical treatment than with surgical intervention.