Biomedical subjects

S Inao

Publications and source records attributed to S Inao.

At least 37 records · Page 2Linked to original sources

PubMed1997

Effect of glycerol on blood flow distribution in tumoral and peritumoral brain tissue.

To evaluate the effect of glycerol, thirty-two patients with brain tumor were directed to the study, including 17 gliomas and 15 meningiomas. Blood flow before and after the administration of glycerol were measured with Xe CT. Glioma was significantly hypo-perfused. The peritumoral edema of glioma and meningioma were also hypo-perfused. On the other hand, Meningioma was significantly hyper-perfused. After the administration of glycerol, blood flows were increased except for glioma. We suggested that, vascular responses to glycerol was different in the two tumor types. The steal phenomena of blood flow might occur in glioma.

Brain Neoplasms↗

PubMed1997

Assessment of vasoreactivity in brain edema by acetazolamide activation SPECT and PET.

Our study was performed to find out cerebrovascular reactivity post acetazolamide administration in patients with peritumoral edema. Adult patients (n = 9) underwent CBF measurement by 99mTc-HMPAO SPECT pre and post 1 gram i.v. acetazolamide. In all patients, this procedure was repeated once again within 10 days of performing tumor removal. Five of these patients also underwent CBF measurement pre and post 1 gram i.v. acetazolamide post surgery only using oxygen-15 labeled H2O PET. Asymmetry index (AI) was calculated as ratio of ROI counts in the peritumoral edematous area and symmetrical ROI on the contralateral normal hemisphere. The AI increased after acetazolamide in edematous gray matter post operatively though the resting AI remained almost same post operatively. AI in edematous white matter showed non-significant increase post operatively both at rest and after acetazolamide. Good linear correlation of AI between PET and SPECT was observed both in gray and white matter. The improvement of vascular reactivity in edematous gray matter after tumor removal suggests that mass effect not only reduces CBF but also suppresses vascular reactivity. White matter vascular reactivity in early post operative period is little improved, possibly due to factors other than mass effect i.e. excess water accumulation in white matter perivascular space.

Acetazolamide↗

PubMed1997

Induction of matrix metalloproteinases following brain injury in rats.

Matrix metalloproteinases (MMPs) are important in various pathophysiological processes related with the tissue remodeling. We planned the experiments to determine whether MMPs participate in disruption and repair of the tissue following brain injury. We have studied induction of MMP-9, a 92 kilodalton (kDa) gelatinase, in traumatic brain tissue, which may be produced by brain residual cells. We speculate that MMP-9 plays a role in post-traumatic brain edema formation.

Animals↗

PubMed1997

Responses of cerebral blood flow regulation to activation of the primary somatosensory cortex during electrical stimulation of the forearm.

We assessed the cerebral blood flow (CBF) response to electrical stimulation of the contralateral forearm over the primary somatosensory cortex (S-I) in anesthetized cats. CBF was monitored continuously using laser-Doppler flowmetry (LDF). In the first set of experiments, the effects of varying stimulus frequency and intensity were examined. During stimulation, CBF in S-I was increased significantly. At high stimulus intensity, response reached a near-plateau level. In the second set of experiments, the CBF response after introduction of an intracerebral mass was investigated using a mechanical microballoon model to simulate an intracerebral hematoma. A microballoon was inserted into the ventral posterolateral nucleus of the thalamus (VPL). Following gradual balloon inflation, there was a rapid reduction in CBF response. We conclude that CBF regulation to neuronal activation is affected by stimulation parameters, and is impaired by an intracerebral mass obstructing the afferent sensory pathway.

Animals↗

PubMed1997

Magnetic resonance imaging quantitation of superior sagittal sinus flow: correlation to cerebral blood flow measured by xenon-enhanced computed tomography.

We compared measurements of venous blood flow velocity in the superior sagittal sinus (SSS) obtained by magnetic resonance imaging (MRI) and quantitative measurements of cerebral blood flow (CBF) obtained by xenon-enhanced CT, in neurosurgical patients and normal volunteers, to assess the clinical usefulness of MRI for determination of CBF. Flow measurements were obtained in 15 neurosurgical patients and 3 normal volunteers. SSS velocimetry was performed using the direct bolus imaging technique with a 1.5-tesla MRI system near the point of lambda on a sagittal MR image. Quantitative CBF was measured by xenon-enhanced CT and correlated with SSS flow velocity. We also examined the effect of surgical evacuation of a hematoma or cranioplasty in 3 patients, mannitol in 5 patients and acetazolamide in 4 patients by performing SSS velocimetry. The peak SSS flow velocity during the entire cardiac cycle was 27.2 +/- 6.3 cm sec-1 (mean +/- SD) in normal volunteers and 23.5 +/- 8.9 cm sec-1 in patients. The SSS flow velocity increased after surgery. Mean SSS peak flow velocity increased by 24% and 48% at 10 min after administration of mannitol and acetazolamide, respectively. SSS peak flow velocity showed significant linear correlations with both cerebral cortical (r = 0.74) and hemispheric flows (r = 0.73). Our results suggest that SSS flow velocity reflects CBF and that MRI assessment of SSS flow provides a simple method for assessing and monitoring global changes in cerebral hemodynamics.

Acetazolamide↗

PubMed1997

Comparison of vasodilatory effect of carbon dioxide inhalation and intravenous acetazolamide on brain vasculature using positron emission tomography.

Carbon dioxide (CO2) and acetazolamide are increasingly being used as vasodilators to detect cerebrovascular reserve capacity in patients of chronic cerebrovascular disease. The functional cerebrovascular reserve or ability of cerebral vessels to lower their resistance in response to decrease in cerebral perfusion pressure is expressed as change in cerebral blood flow from baseline under a vasodilatory stimuli. Theoretically a vasodilator causing maximum vasodilation, and thereby expressing complete reserve capacity would be more suitable for such a purpose. We quantitatively compared the vasodilating effect of 5% CO2 inhalation and 1 g of intravenous acetazolamide by positron emission tomography. Cerebrovascular reserve was quantified in six patients with chronic cerebrovascular disease in the same sitting, using oxygen-15 labeled water (H2(15)O) positron emission tomography at rest, during 5% CO2 inhalation and after 1 g intravenous acetazolamide. A significant linear correlation in both nonlesion hemisphere (r = 0.701, p < 0.001) and in lesion hemisphere (r = 0.626, p < 0.005) was found between CO2 and acetazolamide for cerebrovascular reserve capacity. This correlation improved by considering cerebrovascular reserve per unit change in arterial carbon dioxide (r = 0.744, p < 0.001 in nonlesion hemisphere and r = 0.721, p < 0.001 in lesion hemisphere). The quantitative value of global reserve capacity was different by CO2 stimuli (5.2%) and acetazolamide (49.7%). Though a similar vasodilatory response is elicited by both vasodilators, acetazolamide seems to be more potent and therefore should be preferred to detect patients with exhausted cerebrovascular reserve capacity.

Acetazolamide↗

PubMed1997

Primary Charnley total hip arthroplasty for congenital dysplasia: effect of improved techniques of cementing.

We performed Charnley total hip arthroplasties on 64 patients (71 hips) between 1976 and 1984 for moderate congenital acetabular dysplasia in which a superolateral cement thickness of less than 20 mm was expected when the cup was placed in the true acetabulum at an angle of 45 degrees. Of these, 59 hips were examined 10 to 17 years after operation; 37 (group A) had been operated on between 1976 and 1982 using Charnley's original technique of cementing the acetabulum and 22 (group B) between 1983 and 1984 using more modern techniques. In group A, aseptic loosening of the socket was observed in ten hips (27.0%) and the 17-year survival rate was 81.5%. In group B, loosening was noted in only one socket (4.5%) and the 13-year survival rate was 100%. The improved techniques produced significantly better long-term results in fixation of the cup in dysplastic hips without bone grafting.

Adult↗

PubMed1997

Valgus-extension osteotomy for advanced osteoarthritis in dysplastic hips. Results at 12 to 18 years.

We treated 31 consecutive patients of mean age 43 years (22 to 59) with severe osteoarthritis of the hip secondary to dysplasia by valgus-extension osteotomy. The clinical results were analysed for factors which may have affected the outcome. The procedure was carried out only on one side and was combined with a Chiari pelvic osteotomy in four patients. The angle of valgus was between 30 and 40 degrees with 10 to 20 degrees of extension. The mean follow-up was 15 years (12 to 18). Clinical evaluation using Charnley's modification of the system of Merle d'Aubigné and Postel showed that the mean score for pain had improved from 2.3 before operation to 4.2 at 15 years, and function from 2.3 to 4.2. Range of movement had decreased from 4.2 to 3.5. Fifteen patients (48.4%) had a pain score of 5 or 6 and were evaluated as satisfactory. Kaplan-Meier survivorship analysis showed a survival rate of 51% at 15 years after operation. Two preoperative factors had a significant positive correlation with the radiological results, namely the thickness of the capital drop osteophyte and the length of the roof osteophyte. We suggest that this procedure is effective for advanced osteoarthritis in the dysplastic hip in young and active patients if these factors are satisfactory on the preoperative radiographs.

Adult↗

PubMed1997

Abducens nerve neurinoma--case report.

A 61-year-old female presented with an abducens nerve neurinoma manifesting as diplopia and facial numbness. The tumor was totally removed, and the exact origin was confirmed intraoperatively. Neuroradiological imaging and clinical history are frequently insufficient to obtain an accurate preoperative diagnosis of intracranial neurinoma.

Abducens Nerve↗

PubMed1997

Effect of glycerol on blood flow distribution in tumoral and peritumoral brain tissue.

The effect of glycerol on blood flow in tumoral and peritumoral tissue was measured in 32 patients with brain tumor, 17 gliomas and 15 meningiomas. Blood flow before and after the administration of glycerol was measured by stable xenon-enhanced computed tomography. The tumor part of glioma was significantly hypoperfused. In contrast, the tumor part of meningioma was significantly hyperperfused. Peritumoral edema of both glioma and meningioma was hypoperfused. After the administration of glycerol, blood flow increased in all regions except for the tumor part of glioma. Vascular responses to glycerol may be different in these two tumor types. The steal phenomena of blood flow might occur in cases of glioma.

Adolescent↗

PubMed1997

Human dural thickness measured by ultrasonographic method: reflection of intracranial pressure.

We measured changes in dural thickness to estimate intracranial pressure. The dural thickness on magnetic resonance imaging with contrast enhancement was compared in a hydrocephalic patient before and after shunt operation. Dural thickness also was measured directly using a micrometer at craniotomy for aneurysmal clipping in 11 patients. A small ultrasound probe (5 MHz) was held against the temporal scalp of 10 volunteers to extract convoluted interference echoes from the dura mater using a computer--based system for fast Fourier transform-Cepstrum analysis and maximum entropy analysis. The degree of intracranial pressure in the supine position was varied in the volunteers with transient neck compression. The enhanced dural thickness of the patient with hydrocephalus, barely visualized before shunt operation, increased after surgery. Dural thickness measurements obtained ultrasonographically in the supine position were similar to direct measurements of thickness. Changes in dural thickness on ultrasonography reflect changes in intracranial pressure.

Adolescent↗

PubMed1996

Posterior communicating artery section during surgery for basilar tip aneurysm.

Although dividing the posterior communicating artery (PComA) during surgery has been criticized for increasing the risk of ischaemia, this procedure increase working space improving visibility and the ability to manipulate during treatment of basilar tip aneurysms via the pterional approach. We divided a hypoplastic PComA in 4 of our cases of basilar tip aneurysm. This was necessary because either (1) the length of the PComA and intracranial internal carotid artery (ICA) limited medial retraction of the ICA and access to the basilar bifurcation region, or (2) the PComA and its perforators ran just in front of the aneurysm, interfering with its exposure. We were able to clip the aneurysm neck in all four patients, three of whom had complications including temporary impairment of consciousness, ocular movement disorders and altered sensation in the extremities. Patients with complications showed transient hypersomnolence immediately after surgery; computed tomography showed small thalamic infarctions. However, in two of three patients the ischaemic events occurred contralateral to the side of PComA section. All patients regained consciousness within a week and were discharged with mild ocular movement palsies. In our cases except one with ischaemic complications, thalamic infarction probably resulted from thalamo-perforating artery injury when the aneurysm neck was clipped, rather than tuberothalamic artery injury due to section of the PComA. Taking previous reports and our results into consideration, we believe that division of a hypoplastic PComA is a safe procedure in particular cases when the grade of subarachnoid haemorrhage is not poor and there are no cerebrovascular risk factors, although we realize it is desirable to preserve normal blood flow.

Aged↗

PubMed1996

Intraoperative laser flowmetry reflects levels of cerebral blood flow during neurosurgical procedures.

Changes in cerebral blood flow (CBF) during craniotomies (mean 62.2 years, n = 31) were studied using a laser flowmeter (LFM) to evaluate the utility in CBF monitoring. A small flat probe was applied to the brain surface near the surgical field. The output voltage from LFM was recorded as CBF changes. The percent change in CBF was calculated using the formula [intrasurgical-CBF-control-CBF]/control-CBF x 100. Post-operative neurologic status was evaluated. Control-CBF values were similar among the groups representing different pathologies. The mean CBF decrease ranged from -7.3% following phenytoin injection (n = 9) to -32.7% during induced intrathoracic pressure (n = 10). The mean CBF increase was 41.4% following vascular anastomosis. A decrease > 50% for more than 15 min was associated with a severe permanent neurologic deficit. The CBF monitoring using an LFM during craniotomy may be useful in detecting critical CBF levels for reducing post-operative neurological deficits.

Adolescent↗

PubMed1996

Intercellular adhesion molecule-1 expression on glia following brain injury: participation of interleukin-1 beta.

Interleukin-1 (IL-1), one of the most important inflammatory cytokines, promotes glia to express intercellular adhesion molecule-1 (ICAM-1) in vitro. IL-1 is known to be produced in situ immediately after brain insults and recently we have found that glia, including astrocytes, express ICAM-1 in vivo following cortical stab wounds. To evaluate the participation of IL-1 beta in posttraumatic ICAM-1 expression on glia in vivo, we performed the following experiments. A cortical stab wound was made in the brain of a mouse. ICAM-1-immunopositive glia began to emerge around the wound from 6 h postlesioning. The number of cells reached a maximum at 48 h and persisted until 7 days postlesioning. Next, a neutralizing monoclonal antibody against IL-1 beta was infused into the wound immediately following the injury. This treatment resulted in a significant reduction of ICAM-1-positive glia at 24 and 48 h postlesioning. We conclude, therefore, that IL-1 beta affects ICAM-1 expression on glia in vivo after experimental brain injury and presumably plays an important role in brain wound repair.

Animals↗

PubMed1996

Dynamics of cerebral blood flow and metabolism in patients with cranioplasty as evaluated by 133Xe CT and 31P magnetic resonance spectroscopy.

OBJECTIVE: Prolonged improvement in neurological and mental disorders has been seen after only cranioplasty in patients initially treated with external decompression for high intracranial pressure. The objective was to evaluate, using 133Xe CT and 31P magnetic resonance spectroscopy (MRS), how restoring the bone itself can influence cerebral blood flow and cerebral energy metabolism after high intracranial pressure is attenuated. METHODS: Seven patients (45-65 years old) who had undergone external decompression to prevent uncontrollable intracranial hypertension after acute subarachnoid haemorrhage were evaluated. Cerebral blood flow and metabolic changes were evaluated before and after cranioplasty. RESULTS: The ratio of phosphocreatine to inorganic phosphate (PCr/Pi), which is a sensitive index of cerebral energy depletion, was calculated and beta-ATP was measured. The cerebral blood flow value in the thalamus was normalised, from 44 (SD 9) to 56 (SD 8) ml/100 g/min (P < 0.01) and the value in the hemisphere increased from 26 (SD 3) to 29 (SD 4) ml/100 g/min on the side with the bone defect. The PCr/Pi ratio improved greatly from 2.53 (SD 0.45) to 3.01 (SD 0.24) (P < 0.01). On the normal side, the values of cerebral blood flow and PCr/Pi increased significantly (P < 0.01) after cranioplasty, possibly due to transneural suppression. The pH of brain tissue was unchanged bilaterally after cranioplasty. CONCLUSION: Cranioplasty should be carried out as soon as oedema has disappeared, because a bone defect itself may decrease cerebral blood flow and disturb energy metabolism.

Aged↗

PubMed1996

[Comparison of cerebral blood flow in primary visual cortex by administration of 99mTc-ECD while having eyes open or closed].

Four healthy volunteers were administered 99mTc-ECD while having their eyes open or closed (by an eye mask) on different days and the accumulation of the tracer in their primary visual cortex was compared. The accumulation in the cerebellum and the primary visual cortex was about the same when the volunteers were administered the tracer while having their eyes closed. On the other hand, the accumulation was higher in the primary visual cortex than the cerebellum when the volunteers were administered the tracer while having their eyes open. In the primary visual cortex, the accumulation of the tracer was 15% higher on the average when the tracer was administered while having their eyes open than the value obtained while having their eyes closed. It was assumed that 99mTc-ECD depicted the increase of the regional cerebral blood flow at natural state of opened eyes without active stimuli such as photic stimulation.

Adult↗

PubMed1995

Changes in dural thickness reflect changes in intracranial pressure in dogs.

The thickness of the dura mater was obtained from ultrasound probes on the skull and fast Fourier transform-Cepstrum through a probability process at various intracranial pressures (ICP), measured with pressure transducers, in 12 anesthetized dogs. There was a constant relationship between changes in thickness (micron) and changes in ICP (mmHg) from 5 to 80 mmHg. The estimated thickness at 0 mmHg of pressure and values obtained from measurements of dural samples were very similar. Our method provides estimations of ICP, and holds promise for measuring thicknesses below 1000 microns in biological systems in general.

Anesthesia↗

PubMed1995

Changes in the cerebrocortical capillary network following venous sinus occlusion in cats.

BACKGROUND: Although the important protective effect of venous collateral pathways in sinus occlusion on parenchymal injury has been demonstrated in previous works, the vascular response in the capillary microcirculation itself after cerebral venous occlusion has not been fully elucidated. We examined the morphology of the capillary network after venous occlusion by relating stereologic morphometric parameters to changes in local cerebral blood flow and the development of brain edema. METHODS: Experimental venous sinus occlusion was induced by injection of 0.5 mL of cyanoacrylate into the superior sagittal sinus and by immediate ligation of both external jugular veins in chloralose-urethane anesthetized cats (n = 24). Capillaries in the adjacent cortex (marginal and suprasylvian cortex) and remote cortex (piriform cortex) were injected with Evans blue dye 2 minutes before sacrifice at 15-minute and 120-minute postsinus occlusion. The stereologic morphometric parameters including volume density, minimum intercapillary distance, capillary diameter, and number of perfused capillaries were computed on a fluorescence microscopic photograph using an image analysis system. Cerebral blood flow (CBF) was measured by hydrogen clearance method, and brain tissue water content was measured using the dry-wet method. RESULTS: In the cortex adjacent to the superior sagittal sinus, the volume density and the number of perfused capillaries were increased significantly (p < 0.02, and p < 0.05, respectively) and the minimum intercapillary distance was decreased significantly (p < 0.02) at 15 minutes after venous occlusion (n = 10). Cerebral blood flow (CBF) was also decreased to 53% of that in the control group (p < 0.01). Although the morphologic parameters returned to the control level by 120 minutes after venous occlusion, the CBF remained decreased after venous occlusion. No change was observed in the water content of the adjacent gray matter at 15 minutes after venous occlusion; however, it was increased (p < 0.05) at 120 minutes. CONCLUSION: These results indicate that the recruitment of reserve capillaries occurs during the early phase of venous occlusion. While CBF decreased to half of the control after venous occlusion, capillary perfusion remained above or near the control level until 120 minutes postocclusion, suggesting that venous recruitment would be potentially beneficial in clinical patients in the early stage of venous occlusion.

Animals↗