bluuebunny/crossref_metadata_2025 huggingface dataset:
Pyridine nucleotide redox state and blood flow of the cerebral cortex following middle cerebral artery occlusion in the cat.
Authors: Ginsberg M D , Reivich M , Frinak S , Harbig K
Published: June 2011

Acute changes in the redox state of NADH in the cerebral cortex of cats were investigated following occlusion of the middle cerebral cortex (MCA) and were correlated with alterations of regional cerebral blood flow in the ischemic cortex determined autoradiographically. Arterial occlusion was accomplished via the transorbital approach. Cortical fluorescence and reflected light signals were recorded from the central MCA territory by means of a beam-splitting fluorometer, and a fluorescence signal corrected for alterations in intravascular hemoglobin was derived. Following arterial occlusion, there was a rapid increase in cortical NADH fluorescence, peaking within 30 to 70 seconds at 20% to 40% of full scale. This was followed by a slow linear decline in fluorescence over the next several minutes. The behavior of cortical NADH fluorescence was unaffected by replacement of the ambient air over the cortical surface with nitrogen. Mean regional blood flow values in the most ischemic gyri two to 15 minutes following arterial occlusion were 21% to 23% of the corresponding values in the opposite, nonischemic hemisphere. In individual animals, peak NADH fluorescence values following arterial occlusion correlated with the extent of blood flow reduction in the affected ischemic gyri (P less than 0.05).
Cerebral blood flow regulation: vascular resistance adjustments in the circle of Willis.
Authors: Levy L L , Wallace J D , Stolwijk J A , Poindexter E R
Published: June 2011

Continuous measurements of systemic blood pressure (BP), cerebral perfusion pressure and CBF were accomplished in the cat during transient hypertension, hypercapnia and bilateral carotid artery occlusion. From these measurements resistance values in the circle of Willis and in the cerebral arteries distal to the circle were calculated. The results indicate that the arteries of the circle of Willis and the arteries distal to the circle of Willis dilate and contract independently.
How often are brain infarcts caused by hypotensive episodes?
Authors: Torvik A , Skullerud K
Published: June 2011

Of 135 patients who were resuscitated after cardiac arrest and who died from one day to several weeks later with morphological signs of systemic cerebral anoxia, there were seven patients (5.2%) with brain infarcts probably caused by hypotensive episodes during or after the resuscitation. There was almost no increase in the frequency of recent brain infarcts with an increasing degree of cerebral atherosclerosis (P greater than 0.90). In contrast, the distribution of ten old brain infarcts in the same material showed a significant correlation to the degree of cerebral atherosclerosis (P less than 0.05). The findings suggest that the combination of cerebral atherosclerotic stenoses and hypotensive is not a major cause of brain infarcts in elderly people. It is suggested that the risk of precipitating brain infarcts by lowering BP in hypertensive patients is not much greater in atherosclerotic than in nonatherosclerotic subjects.
Long-term EKG monitoring in patients with cerebrovascular insufficiency.
Authors: McHenry L C , Toole J F , Miller H S
Published: June 2011

Cardiac dysrhythmia may be responsible for signs of cerebrovascular insufficiency in some patients. Ten patients with cerebrovascular insufficiency were monitored for up to 24 hours with the Holter EKG monitor. Eight of the patients had transient ischemic attacks and two had mild deficits from a completed stroke. Eight of the ten patients had associated abnormal cerebral angiography, the most frequent finding being carotid stenosis. Holter EKG monitor in these ten patients showed no abnormalities in four patients. The remaining six had a variety of cardiac dysrhythmias. Although there were a variety of cardiac, cerebrovascular, and neurological abnormalities in these ten patients, six of these patients had a disturbance in cardiac rhythm or conduction which could have been directly associated with or suggest an etiology for the patient's neurological event.
Neurological outcome of prolonged coma survivors of out-of-hospital cardiac arrest.
Authors: Yarnell P R
Published: June 2011

Nine adult survivors of out-of-hospital presumed cardiogenic cardiac arrest, who remained unresponsive for longer than their third hospital day and who eventually were discharged from the acute care hospital, are reported. Their neurological outcome fell into three distinct categories: (a) a persistent vegetative state, (b) able to follow some simple commands but requiring total nursing care, and (c) able to perform most activities of daily living but unemployable because of marked organic deficits.
Studies on the cerebral circulation of the baboon in acutely induced hypertension.
Authors: Strandgaard S , MacKenzie E T , Jones J V , Harper A M
Published: June 2011

The upper limit autoregulation of cerebral blood flow was investigated in eight young baboons with the intracarotid 133xenon clearance method. Blood pressure was increased by intravenous angiotensin infusion. Autoregulation was effective during blood pressure increase from normotensive levels to a mean pressure of 130 to 139 mm Hg. At this pressure, cerebrovascular resistance reached a maximum. With further blood pressure increase, autoregulation was broken, and the vascular resistance dropped significantly. This flow increase was restricted to the fast component of the 133xenon clearance curve, leaving slow component unchanged.
Isolated ophthalmic migraine in the differential diagnosis of cerebro-ocular ischemia.
Authors: Hedges T R , Lackman R D
Published: June 2011

Thirty-three of 129 patients who incurred isolated ophthalmic migraine had monocular attacks of scotomatous visual field loss. Fifteen of 33 patients with monocular attacks had immediate or remote evidence of vascular disease. Four patients had carotid bruits on the same side as the monocular attacks and low ophthalmodynamometer readings. One patient had ischemic optic neuropathy and two had atheromatous disease (advanced stage in one patient). Forty-five percent of the patients with monocular attacks and only 13% of the remaining patients with homonymous attacks had vascular complications. This represents an important finding even in such a small group of patients. It is felt that, whether the vascular problems are trigger mechanisms or coexistence pathology to the migraine-type attack, one should strongly suspect such an association when a patient describes a monocular attack and one should look for a possible vascular explanation other than migraine.
Apolipoprotein localization in human cranial arteries, coronary arteries, and the aorta.
Authors: Hoff H F
Published: June 2011

Apolipoproteins from human plasma high density (HDL), low density (LDL) and very low density lipoproteins (VLDL) were visualized in human arteries employing immunofluorescence techniques. Comparison between the localization patterns in extracranial and intracranial arteries and those in coronary arteries and the aorta was made. ApoA-I from HDL, apoB from LDL, and apoC-III from VLDL, as well as neutral lipid, were all localized to connective tissue and extracellular lipid pools in atherosclerotic lesions, and only to areas of intimal thickening in grossly "uninvolved" arteries. The degree of superposition of localizations was similiar in each vascular bed, and within the error resulting from the structural changes due to the focal nature of the atherosclerotic process. These results suggest a broad specificity in localization of apolipoproteins in most arterial lesions, and suggest that no differences in apolipoprotein accumulation exist between extracranial and intracranial arteries, coronary arteries, or the aorta. Variations in prevalence for atherosclerosis in each arterial bed must be accounted for on other bases.
Mechanisms of postischemic brain edema: contribution of circulatory factors.
Authors: Mchedlishvili G , Kapuściński A , Nikolaishvili L
Published: June 2011

Controlled cerebral ischemia was produced in rabbits by bilateral occlusion of the common carotid arteries and restriction of collateral blood flow by a decrease of the systemic arterial pressure to a desirable level (by hemorrhage into a pressurized reservior system). The following circulatory parameters were simultaneously monitored: systemic arterial pressure (SAP), pressure in the circle of Willis (Pcw), systemic venous pressure (SVP), and pressure in the sagittal venous sinus of brain (Pvs). The cerebral blood flow (CBF) was measured by means of the H2-clearance method, and the brain volume (BrV) changes were evaluated with a mechanical system of the sterotaxic device. It has been concluded that the pre-edematous changes in the brain tissue arise during deep ischemis but an important factor in the brain edema development is the recovery of the CBF with and increase of the intravascular pressure closely related to the brain blood volume augmentation. The latter may be pronouced because of diminution of the blood outflow from the brain when the SVP is increased. The compensation for the BrV increase (caused either by brain blood volume augmentation or by brain edema) is obtained by Pcw decrease probably due to resistance rise in the internal carotid and vertebral arteries. The brain edema may be additionally compensated by an active decrease of the systemic arterial pressure.
Fatal cerebral embolism following aorto-coronary bypass graft surgery.
Authors: Bounds J V , Sandok B A , Barnhorst D A
Published: June 2011

In a case of fatal cerebral embolic infarction following aorto-coronary bypass graft (ACBG) surgery, postmortem examination revealed thrombosis of the vein grafts to the left circumflex and left anterior descending coronary arteries. Continguous with the thrombus in the graft to the circumflex artery was thrombotic material adherent to the aortic sutures and extending several millimeters into the lumen of the aorta. A nonadherent thrombus of similar histologic character was found in the right middle cerebral artery, associated with localized brain infarction. In addition to the risks of cerebral complication associated with other types of open-heart surgery, the location of the vein grafts in patients undergoing ACBG operations seems to offer a unique mechansim for the occurrence of systemic and cerebral embolism, which may be operational in other cases.
Relative role of factors associated with cerebral infarction and cerebral hemorrhage. A matched pair case-control study.
Authors: Abu-Zeid H A , Choi N W , Maini K K , Hsu P H , Nelson N A
Published: June 2011

Comprehensive ascertainment of all possible new cases of stroke appearing between January 1, 1970 and June 30, 1971, and admitted to three major hospitals in Winnipeg, Manitoba, has been achieved by reviewing the Manitoba Health Services Commission claim reports. The medical records of these cases were reviewed, pertinent data were abstracted, and rigid criteria for diagnosis were followed. Also, data were obtained from death certificates, autopsy reports and long-term hospital records. A total of 606 ascertained cases (410 infarction, 137 hemorrhage, and 59 undetermined type) were matched for age, sex, residence and year of admission with 606 controls from admissions for other than cardiovascular and cerebrovascular disorders. The data were analyzed for elucidating the possible risk factors for infarction (INF) and hemorrhage (HGE). The findings suggested that hypertension was the main risk factor in hemorrhage, whereas in infarction, along with hypertension, other factors such as diabetes, heart enlargement in chest x-ray, ECG abnormalities, and smoking were suggested as risk factors. There was an association also between infarction, on one hand, and the history of receiving anticoagulants, diuretics, and medications for the heart, and the occurrence of myocardial infarction, on the other hand. These features indicate that infarction and ischemic heart disease have similar risk factors. Hemoglobin and hematocrit were higher in infarction cases than in their controls only when measured at stroke admission. No difference was revealed when they were measured prior to stroke. Their association with infraction therefore may be secondary to other factors and of no significance for its risk.
Experimental regional cerebral ischemia in the middle cerebral artery territory in primates. Part 1: Angio-anatomy and description of an experimental model with selective embolization of the internal carotid artery bifurcation.
Authors: Watanabe O , Bremer A M , West C R
Published: June 2011

Selective embolization of the internal carotid artery bifurcation (ICA bifurcation) was performed in monkeys (Macaca mulatta) to study acute regional cerebral ischemia in the middle cerebral artery (MCA) territory with minimum surgical intervention in the neck under sedated conditions. The anthropomorphic similarity in angio-anatomy of the carotid system of monkeys and the use of silastic spheres, as artificial emboli, of the critical diameter of 1.2 to 1.4 mm resulted in the overall success rate of 87% in localizing the site of embolization to the ICA bifurcation, producing ischemia in the whole middle cerebral artery territory. All the animals with ICA-bifurcation embolization had contralateral deep motor weakness and conjugate eye deviation with nystagmus toward the site of embolization. Simultaneous EEG recording showed flattening of the basic background activities over the affected MCA area and cerebral arteriograms showed definite retrograde filling of the proximally occluded MCA. Clinical recovery was observed in a few animals within two to five hours of embolization. Gross ischemic swelling in the affected MCA territory, particularly in the gray matter, became obvious in six of eight animals which were exposed to four to five hours of ischemia. The angio-anatomical study of the carotid system of this experimental animal as a background for this MCA stroke model confirmed the previous observations of other investigators that the extremely abundant leptomeningeal anastomoses would be one of the major factors leading to the variability in the clinicopathological pictures seen in the models of proximal MCA occlusion. In addition, the pre-parenchymal anastomoses in the base of brain between the medial striate arteries from the proximal anterior cerebral (ACA) and lateral lenticulostriate arteries from the MCA were observed and described as a possible functional collateral to the basal ganglia in case of proximal MCA occlusion.
Trigeminal artery and occlusive cerebrovascular disease.
Authors: Khodadad G
Published: June 2011

Two patients with persistent trigeminal artery who had an ipsilateral cerebral stroke are presented. The relevant literature is reviewed. The significance of the trigeminal artery in occlusive cerebrovascular disease is discussed and it is concluded that the presence of a trigeminal artery in patients with occlusive cerebrovascular disease may not be of major protective value.
Pleocytosis and elevation of prostaglandins F2a and E2 in cerebrospinal fluid following intracisternal injection of thrombin.
Authors: Hagen A A , Gerber J N , Sweeley C C , White R P , Robertson J T
Published: June 2011

A marked pleocytosis and increase in the levels of prostaglandin F2a (PGF2a) and prostaglandin E2 (PGE2) were noted in cerebrospinal fluid of dogs within two hours following the intracisternal injection of thrombin. Quantitation of the prostaglandins (PG's) was done by gas chromatography-mass spectroscopy using deuterated PGF2a and PGE2 as internal standards. Whereas the levels of these prostaglandins were below the sensitivity of the method in control animals, a marked increase was noted following thrombin. PGF2a levels were 15-21 ng/ml and the PGE2 levels were 55-72 ng/ml. This concentration of the PG's is adequate to cause spasm of the cerebral vessels and could explain the spasm which occurs following the intracisternal injection of thrombin. These two effects, a pleocytosis and elevation of PG levels, may be specific to thrombin.
Apolipoprotein B (apoB) retention in atherosclerotic intracranial arteries.
Authors: Hoff H F , Heideman C L , Gaubatz J W
Published: June 2011

Low (LDL) and very low (VLDL) density lipoproteins retained in grossly normal and atherosclerotic human intracranial arteries have been quantitated using an electro-immunoassay directed against apolipoprotein B (apoB), the major protein of these two lipoprotein fractions. Buffer-homogenates of grossly normal arteries contained apoB amounts ranging from less than 0.04 to 1.58 microng/mg tissue dry weight, while those of atherosclerotic plaques gave values ranging from 0.80 to 3.9 microng per mg tissue dry weight. These results were consistent with immunofluorescence studies localizing apoB in these arteries. Plaques also contained a remaining fraction of tightly-bound apoB as evidenced by positive immunofluorescence in sections of pellets from buffer homogenates. This was in contrast to the negative results from grossly normal arteries. These results would suggest that retention of apoB by intracranial arteries correlates positively with vessel lesions. Arterial apoB is present in both grossly normal regions and plaques in a loosely-bound form, possibly representing intact lipoprotein. ApoB is also present in a tightly-bound form in plaques.
Spectrum subtraction technique for minimizing extracranial influence on cerebral blood flow measurements by 133xenon inhalation.
Authors: Risberg J , Uzzell B P , Obrist W D
Published: June 2011

Estimates of regional cerebral blood flow (rCBF) by the 133Xe inhalation method are influenced by isotope contamination from slow clearing extracerebral tissues. Subtraction of x-ray (31 kev) from gamma-ray counts (81 kev) has been suggested as a means of yielding clearance curves that are relatively free of such contamination. In the present study, rCBF measurements based on the total 133Xe spectrum (x-ray plus gamma) were compared with those derived from the subtracted spectrum (x-ray minus gamma) in 20 young controls, using a two-compartmental analysis of the clearance curves. In comparison with addition, the subtraction data gave substantially higher estimates of blood flow for the slow (second) compartment. This, along with a shift in the relative weights of the two compartments, indicated a decreased contribution of slow tissue components, consistent with a reduction in extracerebral contamination. Blood flow values obtained by subtraction were in good agreement with those reported for the intracarotid injection method. A limitation of the subtraction technique, however, is the relatively high dose of isotope required for adequate signal-to-noise ratios.
Long-term prognosis for cerebral infarction in relation to brain circulation--a 7-year follow up study.
Authors: Fujishima M , Nishimaru K , Omae T
Published: June 2011

Seventy-seven patients with cerebral infarction have been re-examined every year and followed for 7 years. Thirty-one patients had normal cranial blood flow (BF) and the remaining 46 had subnormal cranial BF, determined by the intravenous RISA method at the time of the original attack. During a 7-year follow up, 7 patients (22.6%) of the normal cranial BF group died; 3 of stroke and the remaining 4 from other causes, while 24 patients (52.2%) of the subnormal cranial BF group died; 13 of stroke and the remaining 11 of various diseases. The cumulative survival rate was consistently lower in the subnormal cranial BF group than the normal one. This difference reached statistical significance at 5 and 7 years of follow up. However, stroke recurrence did not differ significantly between the 2 groups. This suggests that a decreased cranial BF is an indicator of a poor long-term prognosis.
Dose dependency of the post-insult protective effect of pentobarbital in the canine experimental stroke model.
Authors: Corkill G , Sivalingam S , Reitan J A , Gilroy B A , Helphrey M G
Published: June 2011

In a canine stroke model, dose dependent protection by postocclusion pentobarbital was suggested from 10--40 mg/kg. In 28 dogs investigated (10 from a previous study) a distinct, significant reduction in right cerebral hemisphere infarction occurred in animals given 15--20 mg/kg pentobarbital intramuscularly 1 hour postocclusion. Increased dosages did not alter statistically the infarct size and 2 dogs at the 50 mg/kg and 80 mg/kg levels died of barbiturate-induced respiratory failure.
Thromboendarterectomy for total occlusion of the internal carotid artery: a reappraisal of risks, success rate and potential benefits.
Authors: Kusunoki T , Rowed D W , Tator C H , Lougheed W M
Published: June 2011

Forty consecutive patients undergoing thromboendarterectomy for total internal carotid artery occlusion were studied in an attempt to determine a) whether careful case selection could be expected to reduce future postoperative mortality and morbidity, b) whether the achieved patency rate justified early operation and c) whether patients in whom patency was restored and maintained had a better long-term prognosis. The results show that a group of patients can be selected that will have low postoperative mortality and morbidity. The success rate for restoration of blood flow is high, particularly if the operation is performed soon after occlusion. The long-term prognosis in patients in whom patency of the internal carotid artery is restored and maintained appears to be better than in those with persistent occlusion of the carotid artery.
Regional brain blood flow in the conscious gerbil.
Authors: Van Uitert R L , Levy D E
Published: June 2011

Regional brain blood flow was determined in 23 awake, unparalyzed gerbils with a simplified indicator-fractionation technique. The use of intravenous 14C-butanol, an indicator that is freely diffusible into the brain, eliminated the need for repetitive sampling of arterial and cerebral venous blood and reduced the period of indicator circulation of 10 seconds. Gerbils spontaneously breathing room air (PaCO2 = 32 +/- 1 (SE) mm Hg) had blood flows in whole cerebrum, cerebellum, and brainstem of 102 +/- 4, 93 +/- 5, and 114 +/- 6 ml/100 gm/min respectively. Cerebral blood flow increased linearly with elevations in PaCO2 (r=0.969) and averaged 3.14 +/- 0.17 ml/100gm/min per mm Hg increase in PaCO2. Interpolated cerebral blood flow at a PaCO2 of 40 mm Hg was 127 +/- 2 ml/100 gm/min. This technique is easy and convenient to use, involves no intracranial surgery, requires steady state conditions for only 10 seconds, and minimizes blood loss in small animals. In more discrete brain regions a less volatile indicator is needed.
Experimental stroke in gerbils: correlation of clinical, pathological and electroencephalographic findings and protein synthesis.
Authors: Yanagihara T
Published: June 2011

Cerebral ischemia was produced in gerbils by ligation of the right common carotid artery and the resulting clinical manifestations and pathological alterations, along with electroencephalographic findings, were followed from 30 minutes to 24 hours. Protein synthesis was evaluated with brain slices in vitro and subsequent cellular and subcellular fractionations. One group of animals developed clinical signs of cerebral ischemia and stroke very rapidly and often died within 12 hours. In these animals cerebral infarction was diffuse in the right side of brain within a few hours post-operatively and there was persistent suppression in the electroencephalographic recordings. Amino acid incorporation into protein of subcellular fractions was decreased to 50% of the opposite side at 30 minutes and further declined to less than 10% in 8 to 10 hours. Another group of animals survived to 24 hours in spite of severe neurological manifestations, and protein synthesis was about 15% of the control side at 24 hours. The suppression of protein synthesis was observed both in the neuronal and neurologlial fractions indicating similar vulnerability of these cellular elements toward cerebral ischemia as shown with cerebral anoxia in the past. It was emphasized that the correlation of clinical manifestations and biochemical data is very important to extract meaningful information from biochemical investigations in this model.
Metabolic profiles of canine cerebrovascular tree: a histochemical study.
Authors: Cook B H , Granger H J , Granger D N , Taylor A E , Smith E E
Published: June 2011

Intriguing questions have recently been raised regarding the applicability of direct observations of the pial microcirculation to the behavior of the total cerebral microcirculation. Operating under the assumption that arteriolar tone and, thus, cerebrovascular resistance is, to some extent, directly related to the intrinsic energy metabolism of the arteriolar wall, a comparative histochemical analysis of cerebral microvessels, both pial and parenchymal, was undertaken. Reactions were chosen on the bases of representation of substrate and of enzymes of glycolysis, the hexose monophosphate shunt, beta-oxidation of fat, Krebs cycle, cytochrome system and ATP hydrolysis. Three metabolically distinct segments of the cerebral microvasculature were delineated with the pial vessels showing strong capacities for glycolysis, beta-oxidation of fats and utilization of glucose through the hexose monophosphate shunt. Microvessels of the gray matter have a qualitatively similar metabolic profile but the capacities of each pathway are lower when compared to pial arterioles. Arterioles of the white matter demonstrate the weakest energy-yielding capacities.
Strokes in children and adolescents.
Authors: Golden G S
Published: June 2011

Strokes in children and adolescents, although rare, are serious when they occur. A practical clinical approach is to differentiate between those events that occur in the presence of systemic disease and those that are restricted conditions involving just the intracranial circulation. Division on the basis of the presence or absence of intracranial hemorrhage further narrows down the differential diagnosis and dictates the urgency with which angiography should be performed. Treatment depends on the underlying condition and on the development of seizures, increased intracranial pressure, or subarachnoid hemorrhage. Prognostic statements are difficult and must be highly individualized.
Experimental cerebral infarction. Part 2: Electroencephalographic changes produced by experimental thalamic infarction in dogs.
Authors: Sakamoto T , Tanaka S , Yoshimoto T , Watanabe T , Suzuki J
Published: June 2011

Previously, one of the authors developed a reliable experimental model in dogs for producing cerebral infarction. The EEG increased detection of experimental cerebral infarction, and was useful in predicting ischemic regions or infarction.
Leptomeningeal artery atherosclerosis visualized by angiography: clinical correlates.
Authors: Knopman D S , Anderson D C , Mastri A , Larson D
Published: June 2011

Circumscribed atherosclerotic involvement of secondary and tertiary branches of major cerebral arteries is a common angiographic finding whose nature is rarely in question. However, widespread and severe changes are unusual, and radiologic interpretation may be more difficult. We recently cared for a patient whose angiogram demonstrated extensive involvement of leptomeningeal vessels and were prompted to review the clinical courses and autopsy findings of a number of other patients with similar angiographic findings. Our observations suggest that the radiological appearance of leptomeningeal artery atherosclerosis can be confused with that of an arteritis. Atherosclerosis of leptomeningeal arteries is strongly associated with a history of arterial hypertension and seems to parallel arterial lesions thought responsible for lacunar infarction and intraparenchymal hemorrhage.
Experimental regional cerebral ischemia in the middle cerebral artery territory in primates. Part 3: effects on brain water and electrolytes in the late phase of acute MCA stroke.
Authors: Bremer A M , Yamada K , West C R
Published: June 2011

Experimental regional cerebral ischemia was produced in the middle cerebral artery (MCA) territory in primates (M. mulatta) by macrosphere embolization. Determinations of percentage tissue dry weight and tissue sodium and potassium concentrations were obtained in samples from the ischemic and non-ischemic hemispheres at various time from 12 to 48 hours after the onset of cerebral ischemia. Samples from the cortex normally supplied by the occluded MCA showed maximal accumulation of edema fluid with fluxes in sodium and potassium in reciprocal directions at 12 hours and similar edematous changes in putamen at 24 hours after embolization By 48 hours after MCA occlusion and despite the presence of infarction, partial reversal was observed in the redistribution of water and electrolytes in these gray matter structures. In contrast to cerebral cortex and putamen, the adjacent subcortical white matter showed progressive increases in water content from 12 to 48 hours and definite increases in tissue sodium with decreases in potassium were not observed until 48 hours after MCA occlusion. This late severe white matter edema associated with cerebral infarction appears to be a major factor responsible for the hemispheric swelling observed at this state.
Free radicals in cerebral ischemia.
Authors: Flamm E S , Demopoulos H B , Seligman M L , Poser R G , Ransohoff J
Published: June 2011

The possibility that cerebral ischemia may initiate a series of pathological free radical reactions within the membrane components of the CNS was investigated in the cat. The normally occurring electron transport radicals require adequate molecular oxygen for orderly transport of electrons and protons. A decrease in tissue oxygen removes the controls over the electron transport radicals, and allows them to initiate pathologic radical reactions among cell membranes such as mitochondria. Pathologic radical reactions result in multiple products, each of which may be present in too small a concentration to permit their detection at early time periods. It is possible to follow the time course, however, by the decrease of a major antioxidant as it is consumed by the pathologic radical reactions. For this reason, ascorbic acid was measured in ischemic and control brain following middle cerebral artery occlusion. There was a progressive decrease in the amount of detectable ascorbic acid ranging from 25% at 1 hour to 65% at 24 hours after occlusion. The reduction of this normally occurring antioxidant and free radical scavenger may indicate consumption of ascorbic acid in an attempt to quench pathologic free radical reactions occurring within the components of cytomembranes.
Effect of DPPD (diphenyl-para-phenylenediamine) on stroke and cerebral edema in gerbils.
Authors: Butterfield J D , McGraw C P
Published: June 2011

Diphenyl-para-phenylenediamine (DPPD) is an antioxidant that has been shown to decrease liver damage due to the peroxidative process of carbon tetrachloride in rats and to ameliorate cold-induced cerebral edema in cats. Because lipid peroxidation disrupts the integrity of the plasma membrane, a process believed to occur in cerebral infraction, which is a major cause of cerebral edema. DPPD was tested for its protective effect against cerebral infarction. When given intraperitoneally in gerbils with unilateral ligation of the common carotid artery, DPPD had no effect on resultant incidence, morbidity, or mortality of cerebral infarction. Despite these findings, the authors believe, on the basis of what is known about free radical pathology, that DPPD and other antioxidants deserve further laboratory trials as possible drugs in the treatment of brain trauma and cerebral edema.
Vasoconstrictor effect of angiotensin on pial arteries.
Authors: Wei E P , Kontos H A , Patterson J L
Published: June 2011

The effect of topical application of angiotensin on pial arterioles was examined in anesthetized cats equipped with a cranial window for the direct observation of the pial microcirculation of the parietal cortex. Angiotensin in a dose of 0.01 to 1 microgram/ml constricted pial arterioles and arteries strongly. The response of the smaller vessels was greater than that of the larger ones. Intravenous administration of angiotensin in a dose of 0.04--3.8 microgram/min raised arterial blood pressure and constricted the larger pial arteries. While the infusion of angiotensin was continued at the same dose, the blood pressure was then reduced to the control level via bleeding into a reservoir. This abolished the vasoconstriction of the larger pial arteries, showing that this effect was due to autoregulatory adjustments to the rise in blood pressure and not due to a direct effect of angiotensin. We conclude that, despite the strong constrictor effect of angiotensin on pial arteries, intravenous angiotensin can be used to study the effects of arterial hypertension on the cerebral circulation.
Cerebral arterial lesions resulting from inflammatory emboli.
Authors: Foote R A , Reagan T J , Sandok B A
Published: June 2011

In order to study the effects of septic embolism on the brain, silicone rubber emboli of various types were injected into the carotid arteries of 35 dogs. Pathologic and angiographic studies were performed to assess the resultant arterial and parenchymal lesions. Pure silicone rubber emboli (14 dogs) produced occasional intra-arterial thrombosis but no arteritis. Sterile and bacterially contaminated emboli containing a lead-chromate pigment (similar to those used in previous studies of septic embolism) (11 dogs) and pure silicone rubber emboli with transversely oriented canals (10 dogs), after brief placement in a bacterial suspension, were associated with intense inflammatory arteritis. This was accompanied by focal meningitis, subarachnoid hemorrhage, thrombosis, and cerebritis of the underlying cortex. The findings resembled those found in mycotic aneurysm. Aneurysmal dilatation was observed in one postmortem angiogram. In previous models of mycotic aneurysm, the inflammation attributed to bacterial contamination was probably due to the lead-chromate pigment used.
Cerebrovascular evaluation: assessment of Doppler scanning of carotid arteries, ophthalmic Doppler flow and cervical bruits.
Authors: Shoumaker R D , Bloch S
Published: June 2011

In 38 patients who underwent cerebrovascular evaluation followed by angiography the Doppler ultrasound scanning technique was found to be an excellent screening procedure for detecting marked stenosis (greater than 50%) or occlusion of the internal carotid artery (93% correlation). It is noninvasive, easily reproducible and can be performed by a qualified technician. The major problems are: the inability to detect ulcerated plaques without marked stenosis, the requirement for patient cooperation (lying still for periods of 15 minutes), and the fact that it assesses only the extracranial circulation. Screening with just the directional ophthalmic Doppler flow signal yielded a high percentage of false negatives (13%). The presence of a cervical bruit may indicate an underlying stenosis of the internal carotid artery, but may also be due to stenosis of the external carotid artery or other factors such as increased blood flow, vessel tortuosity, etc. (12% false positives). Absence of a cervical bruit does not exclude internal carotid artery disease (ulcerated nonstenotic plaque or occlusion).
Cerebral blood flow and metabolism in man following cardiac arrest.
Authors: Beckstead J E , Tweed W A , Lee J , MacKeen W L
Published: June 2011

We measured cerebral oxygen extraction, cerebral blood flow(CBF), and cerebral metabolic rate (CMRO2) in comatose patients during the first 60 hours after resuscitation from cardiac arrest. Each patient was studied 2 or 3 times. CBF was determined by a modification of the Kety-Schmidt method using inhaled Xenon133. Over the study period jugular venous oxygen tension and saturation rose, while the oxygen content difference between arterial and jugular venous blood fell, indicating a progressive increase in the ratio of CBF to metabolism CBF and CMRO2 measurements confirmed this. Between 2 and 6 hours after resuscitation both measurements were severely but proportionately depressed to less than 50% of normal. After 6 hours CBF was increased disproportionately to CMRO2 so that a relative hyperemia developed and persisted for the duration of the study. Although regional inhomogeneity of flow and regional ischemia cannot be ruled out, we have found no evidence for global cerebral ischemia between 2 and 60 hours post-resuscitation as an explanation for failure of recovery. In man following cardiac arrest restoration of levels of global cerebral blood flow, which can be considered adequate relative to the depressed metabolic state of the tissue, is achieved within 2 hours of resuscitation.
Effects of anticoagulants in an animal model of septic cerebral embolization.
Authors: Foote R A , Reagan T J , Sandok B A
Published: June 2011

The effect of anticoagulation on lesions caused by cerebral emboli of different types was studied in 57 dogs. The resultant arterial and parenchymal lesions were assessed by pathologic and angiographic studies. Embolization with emboli that caused little or no inflammatory response in the artery (12 dogs) was not associated with hemorrhagic infarcts or with subdural or subarachnoid hemorrhage; furthermore, treatment with anticoagulants (9 dogs) did not change the character of the lesions. Embolization with emboli that caused arteritis, that is, bacterial contamination or presence of lead chromate in the embolus (21 dogs), was associated with hemorrhagic infarcts, focal subarachnoid hemorrhage, and increased incidence of acute subdural hemorrhage. Treatment with anticoagulants (16 dogs) was associated with a further increase in the incidence of subdural hemorrhage.
Cilostazol Promotes Vascular Smooth Muscles Cell Differentiation Through the cAMP Response Element-Binding Protein-Dependent Pathway
Authors: Chen Wei-Jan , Chen Ying-Hwa , Lin Kwang-Huei , Hsuan Ting Chiao , Yeh Yung-Hsin
Published: June 2011

Objective—

Cilostazol, a potent type 3 phosphodiesterase inhibitor, has recently been found to reduce neointimal formation by inhibiting vascular smooth muscle cell (VSMC) proliferation. The aim of this study is to investigate whether cilostazol exerts an action on phenotypic modulation of VSMCs, another important process in the pathogenesis of neointimal formation.

Methods and Results—

Cilostazol may convert VSMCs from a serum-induced dedifferentiation state to a differentiated state, as indicated by a spindle-shaped morphology and an increase in the expression of smooth muscle cell differentiation marker contractile proteins. The upregulation of contractile proteins by cilostazol involves the cAMP/protein kinase A (PKA) signaling pathway, because the cAMP analog mimicked and specific cAMP/PKA inhibitors opposed the effect of cilostazol. Furthermore, cilostazol-activated cAMP response element (CRE)-binding protein (CREB), including phosphorylation at Ser133 and its nuclear translocation. Deletion and mutational analysis of the contractile protein promoters along with chromatin immunoprecipitation using anti-CREB antibody showed that CRE is essential for cilostazol-induced contractile protein expression. Transfection of dominant-negative CREB (mutated Ser133) plasmid in VSMCs blocked cilostazol-stimulated contractile protein expression. In vivo, cilostazol upregulated contractile proteins and induced the activation of CREB in the neointima of balloon-injured arteries.

Conclusion—

Cilostazol promotes VSMC differentiation through the cAMP/PKA/CREB signaling cascade.
Short Communication: Flecainide Exerts an Antiarrhythmic Effect in a Mouse Model of Catecholaminergic Polymorphic Ventricular Tachycardia by Increasing the Threshold for Triggered Activity
Authors: Liu Nian , Denegri Marco , Ruan Yanfei , Avelino-Cruz José Everardo , Perissi Andrea , Negri Sara , Napolitano Carlo , Coetzee William A. , Boyden Penelope A. , Priori Silvia G.
Published: June 2011

Rationale:

Flecainide prevents arrhythmias in catecholaminergic polymorphic ventricular tachycardia, but the antiarrhythmic mechanism remains unresolved. It is possible for flecainide to directly affect the cardiac ryanodine receptor (RyR2); however, an extracellular site of action is suggested because of the hydrophilic nature of flecainide.

Objective:

To investigate the mechanism for the antiarrhythmic action of flecainide in a RyR2
R4496C+/−
knock-in mouse model of catecholaminergic polymorphic ventricular tachycardia.

Methods and Results:

Flecainide prevented catecholamine-induced sustained ventricular tachycardia in RyR2
R4496C+/−
mice. Cellular studies were performed with isolated RyR2
R4496C+/−
myocytes. Isoproterenol caused the appearance of spontaneous Ca
2+
transients, which were unaffected by flecainide (6 μmol/L). Flecainide did not affect Ca
2+
transient amplitude, decay, or sarcoplasmic reticulum Ca
2+
content. Moreover, it did not affect the frequency of spontaneous Ca
2+
sparks in permeabilized myocytes. In contrast, flecainide effectively prevented triggered activity induced by isoproterenol. The threshold for action potential induction was increased significantly (
P
<0.01), which suggests a primary extracellular antiarrhythmic effect mediated by Na
+
channel blockade.

Conclusions:

Flecainide prevents catecholaminergic polymorphic ventricular tachycardia in RyR2
R4496C+/−
mice; however, at variance with previous reports, we observed minimal effects on intracellular Ca
2+
homeostasis. Our data suggest that the antiarrhythmic activity of the drug is caused by reduction of Na
+
channel availability and by an increase in the threshold for triggered activity.
Aerospace Meteorology: Some Lessons Learned from the Development and Application of NASA Terrestrial Environment Design Criteria
Authors: Vaughan William W. , Johnson Dale L.
Published: June 2011

Aerospace meteorology plays an important role in the design, development, and operation of aerospace vehicles. Many of the issues and lessons presented occurred during the involvement of the authors with the development and interpretation of aerospace environment inputs, especially those of the terrestrial environment. Background for the actions needed to avoid the issue being repeated or the lesson having to be relearned is addressed. The engineering application importance and some issues associated with the presentation and interpretation of terrestrial environment guidelines associated with aerospace meteorology elements are presented.
Measuring Total Column Water Vapor by Pointing an Infrared Thermometer at the Sky
Authors: Mims Forrest M. , Chambers Lin Hartung , Brooks David R.
Published: June 2011

A 2-yr study affirms that the temperature indicated by an inexpensive ($20–$60) IR thermometer pointed at the cloud-free zenith sky (Tz) is a proxy for total column water vapor [precipitable water (PW)]. From 8 September 2008 to 18 October 2010 Tz was measured either at or near solar noon, and occasionally at night, at a field in south-central Texas. PW was measured by a MICROTOPS II sun photometer. The coefficient of correlation (r2) of PW and Tz was 0.90, and the rms difference was 3.2 mm. A comparison of Tz with PW from a GPS site 31 km northnortheast yielded an r2 of 0.79 and an rms difference of 5.8 mm. An expanded study compared Tz from eight IR thermometers with PW at various times during the day and night from 17 May to 18 October 2010, mainly at the Texas site, with an additional 10 days at Hawaii's Mauna Loa Observatory. The best results were provided by two IR thermometers that yielded an r2 of 0.96 and an rms difference with PW of 2.7 mm. The results of both the ongoing 2-yr study and the 5-month comparison show that IR thermometers can measure PW with an accuracy (rms difference/mean PW) approaching 10%, which is the accuracy typically ascribed to sun photometers. The simpler IR method, which works during both day and night, can be easily mastered by students, amateur scientists, and cooperative weather observers.
Microphysical Structure of the Marine Boundary Layer under Strong Wind and Spray Formation as Seen from Simulations Using a 2D Explicit Microphysical Model. Part I: The Impact of Large Eddies
Authors: Shpund J. , Pinsky M. , Khain A.
Published: June 2011

The effects of large eddies (LE) on the marine boundary layer (MBL) microphysics and thermodynamics is investigated using a 2D Lagrangian model with spectral bin microphysics including effects of sea spray. The 600 m × 400 m MBL computational area is covered by 3750 adjacent interacting Lagrangian parcels moving in a turbulent-like flow. A turbulent-like velocity field is designed as a sum of a high number of harmonics with random time-dependent amplitudes and different wavelengths including large eddies with scales of several hundred meters. The model explicitly calculates diffusion growth/evaporation, collisions, and sedimentation of droplets forming both as sea spray droplets and background aerosols, as well as aerosol masses within droplets. The turbulent mixing between parcels is explicitly taken into account. Sea spray generation is determined by a source function depending on the background wind speed assumed in the simulations to be equal to 20 m s−1. The results of simulations obtained by taking into account the effects of LE are compared to those obtained under the assumption that the vertical transport of droplets and passive scalars is caused by small-scale turbulent diffusion. Small-scale turbulence diffusion taken alone leads to an unrealistic MBL structure. Nonlocal mixing of the MBL caused by LE leads to the formation of a well-mixed MBL with a vertical structure close to the observed one. LE lead to an increase in the sensible and latent heat surface fluxes by 50%–100% and transport a significant amount of large spray droplets upward. Microphysical processes lead to formation of spray-induced drizzling clouds with cloud base near the 200-m level.
Effect of Quercetin on CYP3A Activity in Chinese Healthy Participants
Authors: Duan Kai‐Ming , Wang Sai‐Ying , Ouyang Wen , Mao Yan‐Mei , Yang Li‐Jun
Published: June 2011

The aims of this study were to investigate the effect of quercetin on CYP3A activity in vivo. An open, randomized, 2‐period crossover experiment was performed in 18 healthy male volunteers. Genotyped data were available from a total of 165 participants. The allelic frequency was 52.5%. Every volunteer ingested orally 500 mg quercetin or placebo once a day for 13 consecutive days. On day 14, a single 7.5‐mg midazolam tablet was administrated orally. The plasma concentrations of midazolam and 1‐OH‐midazolam were determined over 24 hours. The results showed that coadministration of quercetin in CYP3A5*1/*1 and CYP3A5*1/*3 individuals significantly decreased the area under the curve (AUC0–12 h) of midazolam (160.88 ± 45.58 ng·h/mL vs 188.07 ± 65.75 ng·h/mL, P < .05), significantly decreased the AUC0‐∞ of midazolam (165.46 ± 47.15 ng·h/mL vs 211.84 ± 75.80 ng·h/mL, P < .01), shortened t1/2 (2.06 ± 0.51 h vs 2.75 ± 0.89 h, P < .01), and decreased tmax significantly (0.48 ± 0.36 h vs 1.06 ± 0.69 h, P < .01), respectively. In conclusion, quercetin significantly induced CYP3A activity to substrate midazolam, and the induction was partly related to the CYP3A5 genotype, being more prominent in CYP3A5*1/*1 and CYP3A5*1/*3 individuals.