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K Hashikawa

Publications and source records attributed to K Hashikawa.

53 records · Page 3Linked to original sources
PubMed1994

Split dose iodine-123-IMP SPECT: sequential quantitative regional cerebral blood flow change with pharmacological intervention.

UNLABELLED: At least two quantitative rCBF measurements are needed to evaluate rCBF changes with pharmacological intervention. We have developed the split dose 123I-IMP SPECT method, which enables measurement of rCBF to be repeated in a short time. METHODS: Thirty-one cerebrovascular disease patients were investigated to assess reproducibility and vasoreactivity to acetazolamide. During 44-min dynamic SPECT imaging, 123I-IMP injection and respective arterial sampling were performed twice at an interval of about 25 min. The rCBF values were calculated using a microsphere model in which the washout of 123I-IMP from the brain can be negligible in the first several minutes after injection. For the second rCBF measurement, the remaining activity due to the first 123I-IMP injection was estimated and subtracted from the total brain activity. RESULTS: In ten patients, two consecutive resting mean rCBF values in the MCA territory (CBF1 and CBF2) had good correlation (CBF1 = 47.4 +/- 4.0 (ml/min/100 ml: mean +/- s.d.), CBF2 = 45.2 +/- 8.2, CBF2 = 0.900*CBF1 + 2.9, r = 0.915). In 11 patients with occlusive lesions in the unilateral ICA system, mean rCBF in the MCA territory was increased by only 27.7% +/- 14.0% in the affected side by a 1-g intravenous acetazolamide injection, while 44.5% +/- 12.3% increase was found in the nonaffected side. In 10 patients without a major arterial lesion, a 49.7% +/- 17.0% increase of rCBF was demonstrated. CONCLUSIONS: This split dose method 123I-IMP SPECT can be useful to estimate vascular reserve.

Acetazolamide↗
PubMed1994

Carbon dioxide reactivity by consecutive technetium-99m-HMPAO SPECT in patients with a chronically obstructed major cerebral artery.

UNLABELLED: In the management of major cerebral artery obstruction, cerebral perfusion reserve is key to introducing cerebral revascularization surgery. The purpose of this study was to evaluate the feasibility of assessing cerebral perfusion reserve by consecutive 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) SPECT with 5% carbon dioxide (CO2) inhalation. METHODS: The CO2 inhalation and consecutive 99mTc-HMPAO SPECT study was performed on 30 chronic ischemic cerebrovascular disease patients with unilateral major cerebral artery obstruction and on 27 patients without. CO2 reactivity was expressed as the percent increase of 99mTc-HMPAO accumulation from the baseline (%Change) and as a constant k' that was the ratio of 99mTc-HMPAO accumulation per 1 mmHg change of end-tidal CO2 tension by exponential curve fitting. RESULTS: The mean %Change and k' in the middle cerebral artery (MCA) territory on the side without an obstructive lesion or in the cerebellum ranged from 10.0% to 11.1% and from 0.98% to 1.13% per mmHg, respectively. In the MCA territory, an obstructive lesion was noted in 5.9% versus 0.54% per mmHg in the contralateral MCA territory (p < 0.01). Eleven of 30 patients with major cerebral artery obstruction revealed significant asymmetry in the k' value between bilateral MCA territories. CONCLUSION: The results showed compromised cerebral perfusion reserve in the obstructed major cerebral artery territory. The present method was proven clinically useful for evaluating cerebral perfusion reserve in patients with unilateral major cerebral artery obstruction.

Adult↗
PubMed1993

Non-invasive assessment of acute effects of cigarette smoking on cerebral circulation.

The usefulness of sequential single photon emission computed tomograph technique using Tc-99m hexamethylpropyleneamine oxime was tested to assess the acute effects on cerebral circulation of cigarette smoking and other activation task. The evaluation of reproducibility, photo-stimulation study, and carbon dioxide inhalation study were carried out. In the subjects, who were examined for cerebral perfusion under the resting condition repeatedly, no significant perfusion changes were detected in visual analysis, in quantitative analysis, or in distribution change mapping. The significant increase of CBF in the occipital lobes was found by photo-stimulation. The CO2 reactivity, estimated by a pair of perfusion images obtained under normocapnia and hypercapnia, was lower in the affected side than in the non-affected side of the patients with unilateral major occlusive lesions in the carotid system. These results showed our method was applicable to assess acute effects on regional CBF of cigarette smoking. Five normal volunteers were investigated for the CBF response to cigarette smoking. Although localized CBF increases were detected in two cases, no characteristic pattern could be found. These results suggested that in normal subjects, the effects of cigarette smoking on regional cerebral circulation varied among individuals, depending on the pharmacological properties of the absorbed nicotine including different sensitivity of each subject to nicotine.

Aged↗
PubMed1993

[Quantitative assessment of cerebral blood flow by 123I-IMP SPECT: venous sampling method with hand warming in the water bath].

In order to establish a noninvasive, quantitative method for measuring regional cerebral blood flow (rCBF) by N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPECT, we attempted to employ continuous venous sampling instead of arterial sampling. Forty two patients with cerebrovascular diseases were classified into two groups, with (group II: n = 35) and without (group I: n = 7) hand warming. In group II, either hand was warmed, wrapping in a hot blanket (group IIA) or immersed in a 44 degrees C water bath (group IIB). In each patient, immediately after intravenous bolus injection of 222 MBq IMP, arterial and venous blood samples were collected continuously for 5 min from the radial artery and the cubital vein, respectively. By octanol extraction, IMP was divided into the unmetabolized and metabolized fraction. The ratio of 123I-IMP radioactivity of venous blood compared to arterial blood (pass ratio, referred as %PR) was calculated in three fractions, whole blood, unmetabolized, and metabolized fraction. By using these parameters, we assessed the possibility to estimate the amount of unmetabolized IMP fraction of arterial blood, usually used as an input function, from venous samples. In group I, %PR demonstrated a considerable variation between individuals (whole IMP, 47.5 +/- 24.6% (mean +/- SD): unmetabolized IMP, 46.0 +/- 24.5%: metabolized IMP, 51.8 +/- 27.4%). In group II, especially in group IIB, both increase of %PR value and the decrease in variation (whole, 77.9 +/- 5.6%: unmetabolized, 75.7 +/- 5.7%: metabolized, 86.7 +/- 8.7%) were observed, which permitted the further calculation based on the assumption that %PR value was constant in each IMP fraction (whole blood and unmetabolized fraction).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Memory loss due to transient hypoperfusion in the medial temporal lobes including hippocampus.

A typical case of transient global amnesia (TGA) was investigated with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) with 1.5-tesler scans. During the amnesic episode, a marked decrease of cerebral blood flow was observed in the areas confined to the territory of the bilateral posterior cerebral arteries including the hippocampus. After the episode, cerebral blood flow returned to normal and a circumscribed lesion was detected in the middle portion of CA 1 field of the left hippocampus. The SPECT findings prove direct evidence that the medial temporal structures are involved in the establishment of new memories, as well as in process of recalling only recently acquired memories, but not in retrieval of memories acquired long ago. The MRI findings indicate that a unilateral partial damage to CA 1 sector of the hippocampus does not develop a definite memory impairment and that high-resolution MRI study on the hippocampus is necessary in TGA patients.

Amnesia↗
PubMed1991

[Left unilateral apraxia].

A 32-year-old right-handed man suffered a traffic accident with head injury, resulting in loss of spontaneity, right hemiparesis, severe aphasia, and unilateral apraxia, which was noticed on his non-paralyzed left hand. An MRI scan conducted 11 months after onset revealed a large lesion in the left frontal lobe, a small lesion in the right frontal lobe and a striking thinning of the trunk of the corpus callosum with remarkable dilatation of the lateral ventricles. An IMP-SPECT scan, performed 1 year after onset, showed a diffuse hypoperfusion extending to the left temporo-parietal area further than the MRI verified abnormal density areas. The patient's praxic abilities were precisely evaluated 1 year after onset. The performance on the object use task was characterized by content errors. For example, when using a match with his left hand, he always treated with it like a cigarette. The right hand performance of this task was clumsy due to his right hemiparesis but successful. The performance on his left hand did not improved even when the patient was given visual examples. The term "ideational apraxia" proposed by Liepmann, which was characterized by content errors, implies a conceptual deficit. Morlaas defined ideational apraxia as a agnosia of usage. Ideational apraxia has been so far investigated mainly on patients with these difficulties in both hands. On the other hand, left unilateral apraxia has been explained by callosal disconnection. Liepmann and Maas thought that a lesion of the corpus callosum would prevent the space-time engrams in the left hemisphere from reaching the right sensorimotor area necessary to carry out the skilled act with the left hand, thereby inducing apraxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

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

Platelet destruction mechanism was thought to play a primary role in autoimmune thrombocytopenia (ITP). There is, however, some evidence that anti-platelet antibodies in ITP impair megakaryocytopoiesis. Using autologous In-111 platelets, we tried to elucidate this point. We measured platelet survival, platelet turnover, platelet sequestration sites, and platelet production (turnover) to the clearance (sum of liver and spleen platelet uptake) ratio in 8 normal subjects and 12 patients with ITP whose platelet counts ranged from 9 x 10(9) to 40 x 10(9)/L. The sum of platelet uptake in the liver and spleen showed a significant inverse correlation with platelet survival. Platelet survival, platelet production to clearance ratio correlated significantly with the platelet count. No significant correlation was found between platelet turnover and platelet counts. The distribution of platelet turnover showed considerable individual variation; 8 of 12 patients showed platelet turnovers which were lower than the normal value, but the others were within the normal range. We concluded that although the platelet destruction mechanism in the reticuloendothelial system shows a primary role in thrombocytopenia, the impaired rate of effective thrombopoiesis may also contribute to the severity of ITP.

Adult↗
PubMed1990

[Functional alterations of human platelets following 111In labeling with different ligands and incubation media].

We studied the effects of various 111In-water soluble chelates and incubation media on labeling efficiency of platelets and in vitro platelet aggregability. High labeling efficiency of platelets in ACD-saline was achieved with 111In-oxine sulfate, 111In-tropolone and 111In-MPO (2-mercaptopyridine-N-oxide). In the condition with 4.8 x 10(6)/mm3 platelets in ACD-plasma, 111In-oxine-sulfate had low labeling efficiency and inconsistent labeling, while 111In-tropolone and 111In-MPO had high labeling efficiency. In vitro platelet aggregability (ADP 2 microM) was reduced when platelets were labeled in the absence of plasma. However, there was no significant difference in platelet aggregability among 111In-platelets labeled by three different chelates. In conclusion, to maintain aggregation activity of the platelets with relatively high labeling efficiency, the best result was obtained by using MPO or tropolone chelate in plasma at 4.8 x 10(6)/microliters platelet concentration.

Adult↗
PubMed1990

[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.

Adult↗
PubMed1990

A new apparatus for brain imaging: four-head rotating gamma camera single-photon emission computed tomograph.

The development of a new rotating gamma camera SPECT device for imaging the brain was undertaken with the objective of achieving the highest full volume imaging spatial and temporal resolution performance. For this purpose, four rectangular gamma camera detectors were arranged as close to the head as possible, and united in a block to insure detector head registration and alignment as well as to enable rotation stability at high speeds. Phantom and clinical studies performed demonstrated 42 sequential, 4-mm thick transaxial images acquired in one scan and with sufficient volume to permit the entire cerebrum and cerebellum to be imaged with high sensitivity. The central field of view reconstructed spatial resolution measured 7.0 mm full width of half maximum utilizing the high-resolution collimator, and tomographic images of arbitrary planes including sagittal and coronal demonstrated equally high resolution. The high sensitivity and high speed rotational acquisition capability of the device permits dynamic SPECT studies to be carried out in the analysis of rapidly varying radiotracer concentrations.

Brain↗
PubMed1989

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.

Adult↗
PubMed1988

Iodine-131-labeled fibronectin: potential agent for imaging atherosclerotic lesion and thrombus.

Fibronectin is known to interact with fibrin, collagen, etc. We have labeled fibronectin with 131I, and measured its accumulation in the deendothelialized lesion in the rabbit aorta to evaluate it as a candidate for imaging atherosclerotic lesions and thrombi. Accumulation of [131I] fibronectin in the deendothelialized lesion was apparent at 48 hr, and increased at 72 hr after injection of the agent. Our results indicate that radiolabeled fibronectin may be a useful tracer for imaging early atherosclerotic lesion and thrombus.

Animals↗
PubMed1987

A gamma camera system for atraumatic rCBF measurement using a new super high sensitivity collimator.

The purpose of this study is to develop a useful gamma camera system for atraumatic rCBF measurement by the 133Xe intravenous injection (i.v.) method. A super high sensitivity slant hole (SHS-SL) collimator was designed for this purpose. The gamma camera used with this collimator was able to move close to the patient's head and obtain satisfactory count rates (130 kcpm-178 kcpm in a hemisphere) with a low dosage (10 mCi) of 133Xe. To validate this rCBF measurement system three studies were carried out: a comparative evaluation was performed against the flow values with the intracarotid 133Xe injection (i.c.) method, reproducibility of flow values was assessed from two serial i.v. measurements, and flow values were compared with clinical severity of the patients. The comparative study showed good correlation in the hemispheric and regional values between the two methods; r values 0.98 and 0.64-0.93 for gray matter flow and 0.96 and 0.78-0.93 for initial slope index. In the reproducibility study, the variation coefficients in the hemispheric and regional values between the two serial measurements were 5.0% and 7.3%-14.2% for gray mater flow, 5.2% and 7.9%-12.9% for initial slope index. The reproducibility in this study was as good as those with the i.c. method reported previously. The hemispheric flow values from our gamma camera system correlated well with the clinical severity of cerebrovascular disease. These results show that the gamma camera system with the SHS-SL collimator is useful for atraumatic rCBF measurement.

Brain Ischemia↗
PubMed1987

Effect of hypocapnia on cerebral oxygen metabolism and blood flow in ischemic cerebrovascular disorders.

Effects of hypocapnia on cerebral oxygen consumption (CMRO2) and blood flow (CBF) in cerebral ischemia were studied in 19 patients. The CMRO2 did not change significantly during hypocapnia within the whole group of patients, because 10 out of 19 cases showed a decrease (p less than 0.001) and other 9 showed an increase (p less than 0.01) of CMRO2 during hypocapnia. The first 10 showed higher resting CMRO2 (p less than 0.001) and arteriovenous differences of oxygen content (AVDO2; p less than 0.02) than the other 9. However, the resting CBF and CO2 reactivity to hypocapnia were not different between them, and clinical situations were also similar. A dissociation between flow and metabolism was suggested in the first 10 with rather preserved CMRO2, while reduced metabolic demands were suggested in the other 9. Different responses of CMRO2 to hypocapnia are expected in cerebral ischemia, i.e. in cases with rather preserved CMRO2 it decreases despite an AVDO2 increase, suggesting a capability of CMRO2 to respond to CBF reduction, while it increases in cases with more decreased CMRO2, as the AVDO2 increase exceeds the CBF reduction to maintain the decreased CMRO2 for a further CBF reduction. The vascular CO2 reactivity, therefore, might be maintained to be constant between these patients.

Adult↗
PubMed1985

Synergistic induction of ornithine decarboxylase by diacylglycerol, A23187, and cholera toxin in guinea pig lymphocytes.

When guinea pig lymphocytes were cultured with 1-oleoyl-2-acetyl-glycerol (OAG), A23187, and cholera toxin, ornithine decarboxylase activity was induced synergistically, peaking at 6 h. Addition of 12-O-tetradecanoyl-phorbol 13-acetate (TPA), A23187, and dibutyryl cAMP caused the same kind of induction. Cholera toxin potentiated the ability of A23187 to induce ornithine decarboxylase, but not that of OAG. Dibutyryl cAMP augmented the induction caused by A23187 but not by TPA. These results suggest that both the activation of Ca++-sensitive, phospholipid-dependent protein kinase (protein kinase C) and the increase in intracellular levels of Ca++ and cAMP are necessary for this induction. cAMP may potentiate the induction by modulating a Ca++ messenger system other than that for protein kinase C activation.

Animals↗
PubMedDate not supplied

Effects of caloric vestibular stimulation on parietal and temporal blood flow in human brain: a consecutive technetium-99m-HMPAO spect study.

The effects of caloric vestibular stimulation on regional cerebral blood flow (rCBF) of the parietal and temporal cortex were examined in 10 healthy volunteers. The consecutive 99mTe-hexamethyl-propyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) method with region of interest analysis was used. Changes in rCBF induced by caloric stimulation with cold air (25 degrees C) were evaluated in comparison with those induced by control stimulation with air at body temperature (37 degrees C). Caloric stimulation with cold air induced vertigo in 4 subjects, dizziness in 2, and no sensation of self-motion in the remaining 4 subjects, whereas, control stimulation did not induce the sensation of self-motion in any subject. Although both parietal and temporal rCBF were slightly decreased during caloric stimulation, a correlation could be established between the magnitude of left-right differences in change of parietal rCBF and the degree of self-motion perception induced by cold-air caloric stimulation, as compared to control stimulation. Left-right differences in change of parietal rCBF in subjects with vertigo during caloric stimulation were significantly higher than those in subjects without any sensation of self-motion. In contrast, there was no correlation between the magnitude of left-right difference in change of parietal rCBF and maximum slow phase eye velocity induced by caloric stimulation. These findings suggest that the parietal lobe is involved in the perception of vertigo due to vestibular stimulation, but not in the vestibulo-ocular reflex.

Adult↗