Masatoshi Imaizumi

Decreased cerebrovascular dilatory capacity in subjects with asymptomatic periventricular hyperintensities.

BACKGROUND AND PURPOSE The clinical significance of the periventricular hyperintensity incidentally found on magnetic resonance images of the brain is questionable. We evaluated resting cerebral blood flow and cerebrovascular dilatory capacity of subjects with asymptomatic periventricular hyperintensities to study their cerebral hemodynamics. METHODS Magnetic resonance imaging of the brain was performed in 28 asymptomatic subjects with cerebrovascular risk factors to determine the severity of periventricular hyperintensity. Mean gray matter flow was computed by a 133Xe-clearance technique in subjects at rest and after the administration of 1 g acetazolamide. Flow values were correlated with the scores for periventricular hyperintensity. RESULTS Resting gray matter flow was not significantly correlated with the severity of periventricular hyperintensity for the whole brain (rs = -.364), whereas flow after acetazolamide loading (rs = -.783, P < .001) and the absolute value of increased flow (rs = -.567, P < .01) were significantly and negatively correlated with the severity of periventricular hyperintensity. CONCLUSIONS A decrease in vasodilatory capacity and compensatory vasodilation occur in the cerebral cortex of subjects with asymptomatic periventricular lesions and maintain cerebral blood flow.

An electron microscopic study on the interstitial cells of the gizzard in the love-bird (Uroloncha domestica)

SummaryA type of cells morphologically resembling fibroblasts or Schwann cells and identical with the interstitial cells as firstly described byCajal was studied electronmicroscopically.Examinations of serial sections reveal that cell membranes of these cells make close appositions (nexus) to those of all surrounding smooth muscle cells. The surfaces of these cells are also provided with nerve endings of certain axons derived from plexus myentericus.On the basis of these findings, the possible nature and function of interstitial cells are discussed.

High Signal Intensity on T2-Weighted Magnetic Resonance Imaging and Cerebral Hemodynamic Reserve in Carotid Occlusive Disease

BACKGROUND AND PURPOSE The importance of MR imaging in carotid artery disease is unclear. We evaluated the sensitivity and specificity of the high signal intensity changes on MR images for diagnosis of hemodynamically compromised unilateral internal carotid artery disease. METHODS We evaluated the association of high signal intensities on T2-weighted MR images with changes in cerebral perfusion reserve measured using 99mTc-hexamethylpropyleneamine oxime single-photon emission CT and acetazolamide in 23 patients. RESULTS Eleven patients had a type I response (normal flow and normal perfusion reserve), 8 patients had a type II response (normal flow and decreased perfusion reserve), and 4 patients had a type III response (decreased flow and decreased perfusion reserve). High signal intensities in the centrum semiovale (11/12) and/or posterior periventricular white matter (6/12) were frequently seen in the hemodynamically compromised groups. Extensive high signal intensities were associated with severely impaired cerebral circulation. MR imaging had high sensitivity (0.92) and specificity (1.0) in predicting hemodynamically compromised patients when we used the presence of T2 high intensity in the centrum semiovale as a criterion. CONCLUSIONS The centrum semiovale T2 hyperintensities lateralized to the side of carotid occlusion are specific and sensitive for the presence and severity of hemodynamic compromise from carotid occlusive disease.

Subclavian steal in Takayasu's arteritis. A hemodynamic study by means of ultrasonic Doppler flowmetry.

Blood flow in the vertebral artery and the upper extremity was studied in five cases of Takayasus arteritis with subclavian steal by use of ultrasonic Doppler flowmetry and finger plethysmography. The diagnosis of subclavian steal was made by observation of flow reversal in the vertebral artery on the subclavian steal side during grip exercise and, in addition, the vertebral flow change with brachial artery occlusion. The blood flow increase of both internal carotid and non-affected (non-subclavian steal side) vertebral arteries during a common carotid compression was almost normal in patients with Takayasus arteritis in this study. During carotid compression on the side of the subclavian steal, ipsilateral vertebral blood flow greatly decreased, and the amplitude of the ipsilateral finger plethysmogram decreased slightly or moderately. It is suggested that there are significantly important factors in suppressing symptoms of vertebrobasilar ischemia in these patients with Takayasus arteritis with subclavian steal. These factors are believed to be (1) good function of the circle of Willis, (2) good blood supply to the brain stem, and (3) collateral circulation to the distal subclavian artery not via the vertebral artery.

Platelet production, clearance and distribution in patients with idiopathic thrombocytopenic purpura

We have studied 8 normal subjects, and 12 patients with idiopathic thrombocytopenic purpura whose platelet counts ranged from 9 x 10(9)/L to 40 x 10(9)/L. Autologous platelets labeled with 111Intropolone were used for evaluation of mean platelet survival, platelet turnover, platelet sequestration sites, and platelet production (turnover) to clearance (sum of platelet uptake in the liver and the spleen) ratio. Platelet survival correlated directly with platelet counts. There was no significant correlation between the platelet sequestration pattern and platelet count, survival, or turnover. Sum of platelet uptake in the liver and the spleen showed a significant inverse correlation with platelet survival. No significant correlation was found between platelet turnover and platelet count. There was a significant correlation between the platelet production to clearance index when all subjects were analyzed. The distribution of platelet turnover showed considerable individual variation; eight of twelve patients showed platelet turnover less than mean minus 2SD of the control value, but others showed normal range. We conclude that although platelet destruction mechanism in RES shows a primary role of thrombocytopenia, impaired rate of effective thrombopoiesis may also contribute to disease severity in ITP.

Plasma concentrations of thromboxane B2 in patients with hypertension or cerebrovascular disease

Abstract The peripheral venous plasma levels of thromboxane B 2 (TxB 2 ) were determined by radioimmunoassay in 22 control subjects, 12 patients with essential hypertension, 15 patients with cerebrovascular disease (CVD) not taking aspirin and 14 patients with CVD taking aspirin. There was no significant difference in TxB 2 levels among the control subjects, hypertensive patients and CVD patients not taking aspirin. In CVD patients taking aspirin, the plasma TxB 2 levels were significantly lower than those in the other groups. The internal jugular venous concentrations of TxB 2 were measured in 10 CVD patients not taking aspirin. Four of 10 studied patients exhibited significant increases only in the internal jugular venous TxB 2 levels, while peripheral venous and/or femoral arterial TxB 2 levels were not significantly different from peripheral venous TxB 2 levels of control subjects.

Behcet's disease with sinus thrombosis and arteriovenous malformation in brain

SummaryA 55-year-old man suffered from Behcets disease with bilateral sigmoid sinus thrombosis and dural arteriovenous malformation has been studied clinically and pathologically. A possible causal relationship between Behcets disease and sigmoid sinus thrombosis is discussed.ZusammenfassungBei einem 55jährigen Patienten mit Behcetscher Krankheit fand sich sowohl eine Thrombose des Sinussigmoides wie auch eine arteriovenöse Mißbildung der Dura und des Gehirnes. Es wird über das Ergebnis der klinischen und pathologisch-anatomischen Untersuchung dieses Falles berichtet und die möglichen Beziehungen zwischen den obengenannten Besonderheiten des Falles untereinander kommentiert.

Evaluation of cross-circulation through circle of Willis using an ultrasonic Doppler technique. Part I. Comparison between blood flow velocity by ultrasonic Doppler flowmetry and angiogram.

In 24 patients with cerebrovascular disease and 6 without organic brain lesions, the increased Telocity of blood flow in both the internal carotid and rertebral arteries daring a contralateral carotid compression was compared with the angiographlc appearance of the drde of Willis. The flow vdodty was measured using ultrasonic Doppler flowmetry. It was not possible to investigate fully the relationship between the increase of velocity of blood flow in the internal carotid artery and the anatomical variations of the circle of Willis, specifically the anterior cerebral and communicating arteries. The velocity of flow in the patients with an aplastic proximal portion of the anterior cerebral artery showed no increase. There were no differences in the increase of velocity of flow in the vertebral artery in patients with hypoplastk, normal and fetal posterior communicating arteries. It is considered that although anatomical variations of the drde vessels influence the cross-drculation via the drde of Willis, peripheral vascular factors distal to the drde also play an Important role in the quantity of cross-circulation through the drde. Stroke, Voll2, No4, 1981

Platelet aggregability and in vivo platelet deposition in patients with ischemic cerebrovascular disease - evaluation by indium-111-platelet scintigraphy -

In ischemic cerebrovascular disease, it is not clear whether platelet function in vitro actually reflects the situation in vivo. Using indium-111 platelet scintigraphy as a method for detecting platelet activation in vivo, we tried to elucidate this problem. Twenty eight patients with chronic stage of ischemic cerebrovascular disease (CVD) and 17 control subjects were examined. Platelet scintigrams were positive in 9 of 28 patients in CVD, while all were negative in control. A comparison of the results obtained from qualitative platelet imaging and platelet aggregability was performed to evaluate whether threshold aggregation concentration (TAC) grade differed across the three groups (control, CVD patients without platelet deposition and CVD patients with platelet deposition). CVD patients with platelet deposition showed a higher TAC than those patients who did not show platelet deposition (P less than 0.05) or control subjects without platelet deposition (P less than 0.05). These results suggest that some patients in chronic stages of CVD may have active platelet deposition on carotid atheromatous lesions, and presence of platelet deposition in vivo could contribute to reduce platelet reactivity in peripheral blood.

Noninvasive Measurement of Cerebral Blood Flow With 99mTc-Hexamethylpropyleneamine Oxime Single-Photon Emission Computed Tomography and 1-Point Venous Blood Sampling

Background and Purpose The arterial and venous blood concentration of technetium 99m–labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) reaches an equilibration more rapidly than other CBF tracers. We hypothesized that 99mTc radioactivity of a venous sample at equilibrium, which is similar to that of an arterial sample, would allow estimation of the integrated input function for the clinical measurement of CBF by use of single-photon emission CT. Methods In 53 patients with stable cerebrovascular disease, the radioactivity of a venous sample 5 minutes after injection of 99mTc-HMPAO was correlated with 5-minute arterial blood radioactivity and the first 5 minutes of the integrated arterial curves of the lipophilic tracer. The measured CBF values were compared with those of xenon 133. Results The radioactivity of 5-minute venous blood was almost equivalent to that of 5-minute arterial blood (r2=0.987;y =0.993 x +1.63;P <0.0001). The correlation between the venous blood radioactivity and the integrated arterial lipophilic fraction was excellent (r2=0.935, P <0.0001). A strong correlation was obtained between 99mTc-HMPAO and 133Xe CBF values (r2=0.825, P <0.0001). CBF values were reproducible (coefficient of variation, 8.6%). Conclusions This approach is fast, simple, and an alternative to continuous blood sampling in clinical quantitative 99mTc-HMPAO CBF studies.