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J Yoshida

Publications and source records attributed to J Yoshida.

At least 199 records · Page 11Linked to original sources
PubMed1997

Vasodilator effects of C-type natriuretic peptide on cerebral arterioles in rats.

The vasodilator effects of C-type natriuretic peptide (CNP) were investigated in isolated rat cerebral arterioles. CNP caused dose-dependent vasodilation, maximally by 10.0 +/- 2.2% at 10(-6) M. The median effective concentration (EC50) was 5.2 x 10(-10) M. In contrast, atrial natriuretic peptide and B-type natriuretic peptide, other members of the natriuretic peptide family, produced little or no vasodilation. Pretreatment with methylene blue (10(-4) M) abolished CNP-induced vasodilation, whereas pretreatment with NG-monomethyl-L-arginine or indomethacin did not inhibit vasodilation. Thus, CNP is suggested to cause significant vasodilation in cerebral arterioles via a cyclic guanosine monophosphate-dependent mechanism.

Animals↗
PubMed1997

Granulocyte colony stimulating factor-producing tongue carcinoma.

BACKGROUND: Leukocytosis without infection in patients with malignancies is known as the leukemoid reaction. The mechanisms involved in this phenomenon remain uncertain. METHODS: We describe the clinical, biochemical and immunohistochemical findings in a patient with recurrent tongue carcinoma accompanied by marked leukocytosis as high as 96200/ mm3. RESULTS: The serum granulocyte colony stimulating factor (G-CSF) concentration was increased to 204 (normal: < 30) pg/ml, which paralleled to the elevation of white blood cell (WBC) count and the tumor growth. The G-CSF content of the tumor tissue was also elevated (131 pg/mg protein) compared to that in control patients (6.63 +/- 2.63 pg/mg protein). Production of G-CSF from the tumor was evidenced by immunohistochemical staining with monoclonal antibody against human recombinant G-CSF. CONCLUSIONS: We suggest that the G-CSF production of the tumor participates in the mechanisms of the leukemoid reaction.

Aged↗
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

A new table-fixed soft tissue retractor for the anterior cervical spinal surgery.

Since surgeons sometimes encounter difficulty in keeping self- retaining soft tissue retractors in the proper position for anterior cervical spinal surgery, we have developed a new, simple soft tissue retractor system, which is fixed to the side rails of the operating table via retractor stands. All three joints of the retractor can be tightened simultaneously with a single handle. Each of two retractor blades can keep its position independent of the other thereby maintaining a well-exposed operative field for a long period of time. Fine adjustments of the blade position, after fixation of the retractors, is possible by sliding the head of the blade assembly along the axis of a ratchet mechanism. We have used these retractors in 43 surgical exposures, including 35 for anterior cervical fusion, 2 for posterior thoraco-lumbar decompression, and 6 for carotid endarterectomy. There have been no complications related to tissue damage.

Cervical Vertebrae↗
PubMed1997

Accessory parotid gland tumor: a case report.

We report a case of pleomorphic adenoma which was assessed pre-operatively as arising from the accessory parotid gland. Computed tomography (CT)-sialography provided information about the relationship between the tumor and the remaining normal accessory parotid tissue, and fine-needle aspiration of the tumor provided additional information as to the histologic features of the tumor, i.e. it was identified as of salivary origin. Zygomatic and buccal branches of the facial nerve extended over the accessory parotid gland tumor and the parotid duct was located just beneath the tumor. Therefore, pre-operative assessment of the tumor's nature was important for prevention of facial nerve damage and salivary fistula. The normal accessory parotid gland tissue associated with the accessory parotid tumor was histologically different from that of normal parotid gland tissue dissected in other patients with pleomorphic adenoma of the parotid gland. It is suggested that the difference in cell composition between these glands affects the development of the associated tumors.

Adenoma, Pleomorphic↗
PubMed1997

Warthin's tumor of the parotid gland with extension into the parapharyngeal space.

A case of Warthin's tumor of the parotid gland which extensively extended into the parapharyngeal space is presented. The tumor border against the parotid gland was ill-defined but the border towards the parapharyngeal structures was clear. Solid portions of the tumor appeared hypointense relative to the gland on both unenhanced T1- and T2-weighted MR images without fat suppression, whereas cystic portions appeared hypointense on T2-weighted images and hyperintense on unenhanced T1-weighted images. Pathologic study showed that the ill-defined margin was caused by inflammation and cystic material consisted of highly proteinaceous material. We concluded that the atypical extension into the parapharyngeal space of the tumor was caused by its location in the deep lobe of the parotid gland and its bulky size.

Adenolymphoma↗
PubMed1997

Assessment of parotid masses: which MR pulse sequences are optimal?

The objective of this paper is to determine which MR pulse sequences are optimal for delineation of lesion and predicting pathologic nature of lesion with signal intensity. A prospective study was performed in 53 parotid masses (39 benign and 14 malignant lesions) in 53 patients. Signal intensity of lesion was visually assessed and lesion/parotid contrast-to-noise ratios were measured. On visual assessment, detection sensitivity was 100% for nonenhanced nonfat-suppressed T1-weighted images, 91% for nonfat-suppressed fast spin-echo (FSE) T2-weighted images, 83% for gadolinium-enhanced fat-suppressed T1-weighted images, and 75% for fat-suppressed FSE T2-weighted images. The highest contrast-to-noise ratios were obtained with nonenhanced T1-weighted images. Hypointensity of lesion relative to the parotid gland on nonfat-suppressed FSE T2-weighted images was seen in 11 of 14 malignancies, 12 of 15 Warthin tumors, and two of 18 pleomorphic adenomas. Cystic portion of hyperintensity on nonenhanced T1-weighted images was solely seen in benign tumors (n = 11). Thus, the highest accuracy (81%) (79% sensitivity and 82% specificity) for predicting malignancy was obtained with a criterion of hypointensity on nonfat-suppressed FSE T2-weighted images plus absence of cystic portion of hyperintensity on nonenhanced T1-weighted images. Nonenhanced T1-weighted images combined with nonfat-suppressed FSE T2-weighted images is optimal for delineation of lesion and prediction of pathologic nature of parotid masses.

Adolescent↗
PubMed1997

Augmentation of anti-Fas antibody-mediated apoptosis on human glioma cells by liposomes associated with the antibody.

We investigated the susceptibility of five human glioma cell lines to anti-Fas antibody. All human glioma cells tested constitutively expressed Fas antigen on their surfaces and the level of the expression varied slightly in each cell line. The cells had a low susceptibility to anti-Fas antibody-mediated apoptosis. There were four moderately resistant cell lines (U251-SP, U251-MG, SK-MG-1, T98) and one highly resistant cell line (U251 nu/nu). For this study we prepared liposomes containing anti-Fas antibody and studied the augmentation of the antibody-mediated apoptosis. The liposomes induced apoptosis significantly more often than did anti-Fas antibody alone. These results indicate that anti-Fas antibody-mediated apoptosis does not require a critical level of cell surface expression of Fas antigen but rather depends on the intensity of Fas signal transduction.

Antibodies, Monoclonal↗
PubMed1997

Experimental use of semiconductor diode laser for neuroendoscopic surgery.

The authors demonstrate an experimental use of the newly developed high power aluminium-gallium-arsenide (AlGaAr) diode laser (DIOMED 25, Olympus Optical Company, Tokyo, Japan). The unit consists of a compact body and fiberoptic probes with small accessories. There are two types (contact and non-contact) of probes. Tissue effects on rat liver, femoral artery, and brain tissue were examined. Adding that, we measured the thermal changes on the liver surface produced by the laser beam with a thermography system. For coagulation with the contact probe, 5 or 7 W was adequate but 10 W was too excess because of tissue adhesion. For cutting, low absorption of the laser in less vascularized tissue like brain white matter provided a deeper tissue damage compared with more vascularized tissue. The temperature at the center reached over 100 degrees C during 10 seconds after laser treatment with the cutting probe. These findings suggest that this system proved to be a good candidate for endoscopic hemostasis and cutting with meticulous maneuver.

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

Intravenous infusion of adrenomedullin and increase in regional cerebral blood flow and prevention of ischemic brain injury after middle cerebral artery occlusion in rats.

The intravenous infusion of rat adrenomedullin, at concentrations ranging from 0.1 to 1.0 microgram/kg/min, for 60 min increased the regional cerebral blood flow (rCBF) in a dose-dependent manner in rats. rCBF was measured using a laser Doppler flowmetry device placed on the surface of the parietal cortex. The increase in rCBF induced by 1.0 microgram/kg/min of adrenomedullin was up to 145 +/- 10.8% of controls at 60 min (n = 5, p < 0.001). These concentrations of adrenomedullin did not affect systemic blood pressure or other physiologic parameters, including pH, PaCO2, PaO2, hemoglobin, and blood glucose. Repeated infusion of 1.0 microgram/kg/min of adrenomedullin at 2-h intervals caused tachyphylaxis (n = 5, p < 0.01). Rat adrenomedullin (1.0 microgram/kg/min) demonstrated a more potent effect than the same dose of human adrenomedullin. The C-terminal fragment of human adrenomedullin (0.5 and 5.0 micrograms/kg/min), adrenomedullin22-52, which did not affect rCBF alone, inhibited the effect of rat adrenomedullin (0.5 microgram/kg/min) as a receptor antagonist in a dose-dependent manner. In a model of middle cerebral artery (MCA) occlusion in spontaneously hypertensive rats, pre- and postinfusion of 1.0 microgram/kg/min of adrenomedullin suppressed the reduction in rCBF following MCA occlusion (control, 29 +/- 15.1%; adrenomedullin group, 45 +/- 14.4%; not significant) and decreased the volume of ischemic brain injury (control, 288 +/- 35 mm3; adrenomedullin group, 232 +/- 35 mm3; p < 0.05). These results suggest that adrenomedullin increases rCBF and prevents ischemic brain injury, partly by increasing the collateral circulation.

Adrenomedullin↗
PubMed1997

Vasodilator effects on canine basilar artery induced by intracisternal interleukin-1 beta.

The effect of interleukin-1 beta (IL-1 beta) on a cerebral artery was investigated in anesthetized dogs. Intracisternal administration of IL-1 beta (0.03 and 0.3 micrograms) dilated the canine basilar artery in a dose-dependent manner, without affecting systemic blood pressure or heart rate. The increase in diameter induced by 0.3 micrograms of IL-1 beta was 28.4% +/- 13.4% of control at 2 hours and was inhibited by 30 micrograms of the IL-1 beta receptor antagonist, zinc protoporphyrin (4.5% +/- 13.5%, P < 0.05). Interleukin-1 beta did not affect the concentration of nitric oxide metabolites in CSF. However, there was an increase in the concentration of eicosanoids in CSF, and the elevation of 6-keto-PGF1 alpha paralleled the vasodilation. Pretreatment with 30 micrograms of the selective inducible cyclooxygenase (COX-2) inhibitor NS-398 also inhibited the IL-1 beta-induced vasodilation significantly (5.9% +/- 9.4% at 2 hours, P < 0.01). Western blot analysis revealed the expression of a 68-kD COX-2-like protein in basilar artery extracts. These findings suggest that the IL-1 beta-induced vasodilator effect is linked to the prostaglandin cascade, predominantly to prostaglandin I2, by induction of COX-2, but not to the stimulation of nitric oxide metabolism.

Animals↗
PubMed1997

Surgical treatment for pediatric moyamoya disease: use of the superficial temporal artery for both areas supplied by the anterior and middle cerebral arteries.

OBJECTIVE: To revascularize ischemic territories of both the anterior cerebral artery (ACA) and the middle cerebral artery (MCA), a simple and effective combined bypass operation was performed in 36 pediatric patients with moyamoya disease during the past 8 years. METHODS: The branches of the superficial temporal artery (STA) were used to revascularize the ACA and MCA territories. In children older than 5 years, the parietal branch of the STA was usually used for an end to side anastomosis with a cortical branch of the MCA. In children who were younger than 5 years, the parietal branch of the STA was used for an encephaloduroarteriosynangiosis instead of a direct anastomosis. Encephaloduroarteriosynangiosis, using the proximal part of the intact frontal branch of the STA, and encephalomyosynangiosis, using the temporal muscle, were also performed in all patients to stimulate spontaneous anastomosis. In addition, bilateral frontal burr holes were made in all patients to induce vascularization of the ACA territories from the distal part of the intact frontal branch of the STA. The first operation was performed on the dominant side, then a similar procedure was performed on the opposite side after an interval of at least 3 months. RESULTS: Postoperative clinical symptoms and the findings from magnetic resonance imaging, magnetic resonance angiography, angiography, and electroencephalography demonstrated improvement in all patients. CONCLUSION: These results suggest that the placement of bilateral burr holes (while leaving the frontal branch of the STA intact), in addition to the STA-MCA anastomosis, encephaloduroarteriosynangiosis, and encephalomyosynangiosis, is very effective in vascularizing the ischemic ACA and MCA territories in pediatric patients with moyamoya disease.

Adolescent↗