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Biomedical subjects

Y Fukuuchi

Publications and source records attributed to Y Fukuuchi.

At least 19 recordsLinked to original sources
PubMed1998

Platelet adhesion to aortic endothelial cells in vitro after thrombin treatment: observation with video-enhanced contrast microscopy.

Secondary thrombus formation following arterial occlusion is suggested to play an important role in the exacerbation of ischemic organ damage. We investigated the effect of thrombin on endothelial cells from the aspect of morphological changes and induction of platelet adhesion to the endothelial cells. Using a video-enhanced contrast microscopy, we observed human aortic endothelial cells (HAEC) following perfusion of human alpha-thrombin of 1.0 U/ml (n = 7) or vehicle (n = 7) for 30 minutes. The endothelial cells began to shrink 15 minutes after thrombin administration. Gaps between the cells were formed. The cells became rearranged orderly in the same direction 30 minutes later. In another study, following pretreatment with human alpha-thrombin 1.0 U/ml (n = 10) or vehicle (n = 7) for 20 minutes and washout, platelets were perfused over HAEC for 30 minutes. Platelets adhered directly to thrombin-treated endothelial cells and became flat on the endothelial cells. Then other platelets were observed to approach to the flattened platelets and aggregated onto it. After washout of floating platelets, adhesion of platelets was further confirmed. These results suggest that thrombin may be involved in the endothelial damage and formation of platelet thrombi on the endothelial cells after blood flow disturbance.

Aorta↗
PubMed1998

Microglia-specific localisation of a novel calcium binding protein, Iba1.

Recently it has been shown that mRNA of Iba1 (ionized calcium binding adaptor molecule 1), which was a novel calcium binding protein cDNA-cloned by our group, is specifically expressed in microglia in cultures of rat brain cells [Imai et al. Biophys. Biochem. Res. Commun., 224 (1996) 855-862]. In the present study, immunocytochemical and immunohistochemical examinations demonstrated that Iba1 protein is expressed in microglia alone both in cultured brain cells and in the brain, respectively. In a mixed cell culture of embryonic rat brain, immunocytochemically positive for Iba1 protein were the microglia but it was not detectable in neurons, astroglia, or oligodendroglia. Immunohistochemical staining of adult rat brain sections showed Iba1 protein to be specifically localised in ramified microglia. In addition, immunohistochemical staining and immunoblot analysis of activated microglia in the facial nucleus after facial nerve axotomy shows that expression of Iba1 protein was upregulated and peaked at 7 days. These results indicated that localisation of Iba1 protein is restricted to microglia both in vitro and in vivo, and that Iba1 protein plays a role in regulating the function of microglia, especially in the activated microglia.

Animals↗
PubMed1998

Binding capacity of FK506 binding protein after 2-hour hemispheric ischemia in gerbil brain.

The binding capacity of FK506 binding protein (FKBP) was examined after 2-h hemispheric ischemia in the gerbil brain in order to clarify the precise mechanism of the neuroprotective effects of FK506. Firstly, the FK506 binding was evaluated in vitro in the normal gerbil brain using 1 nM [3H]dihydro-FK506 as a specific ligand. FK506 binding sites were distributed in a rather homogeneous manner, although the greatest binding was noted in the hippocampus CA1. Secondly, Scatchard analysis demonstrated that the binding sites of FK506 could be composed of two components in each brain region. Thirdly, 18 Mongolian gerbils were divided into two groups: an ischemia group (n = 12) and a sham group (n = 6). The right common carotid artery was ligated to induce hemispheric ischemia for 2 h in the ischemia group. The local cerebral blood flow was measured at the end of the experiment by the [14C]iodoantipyrine method. The ligated animals with levels of local cerebral blood flow in the lateral nuclei of the thalamus of less than 50 ml/100 g/min were utilized as the ischemia group (n=6) for further data analysis. No significant differences in FK506 binding between the ischemia and sham groups were observed in any regions. The above data indicate that the binding capacity of FKBP tends to remain normal during 2-h ischemia, suggesting that FK506 may exert its neuroprotective effects through its binding to FKBP in the brain during the early phase of cerebral ischemia.

Animals↗
PubMed1998

Hydrogen peroxide enhances phagocytic activity of ameboid microglia.

Microglia are considered to serve as a guardian of the brain. In achieving this task, they have been observed to transform into a reactive form and then an ameboid form. Several substances are implicated in the control of such behavior. We examined the effect of hydrogen peroxide on cultured microglia of ameboid form obtained from the fetal rat brain employing video-enhanced contrast-differential interference contrast microscopy. Microglia harvested from the culture bottle were observed to float in a spherical shape with abundant filopodia on the surface. However, on coming into contact with the glass surface of a cover slip, they immediately transformed into an ameboid form. The microglia spread themselves out, surrounded by thin transparent lammellipodia, which would not be clearly observable by either light microscopy or electron microscopy. In a concentration-dependent fashion, 10(-3)-10(-1) M hydrogen peroxide solution enhanced the ruffling process of the lamellipodia and formation of vesicles (phagosomes), which displayed a typical phagocytotic form. It is concluded that an increase in free radicals in ischemic tissue tends to facilitate the phagocytosis of ameboid microglia as macrophages.

Animals↗
PubMed1998

Novel mutations of the peripheral myelin protein 22 gene in two pedigrees with Dejerine-Sottas disease.

Peripheral myelin protein 22 (PMP22), a membrane glycoprotein, plays a significant role in the formation and/or maintenance of compact myelin in the peripheral nervous system. We studied two pedigrees with Dejerine-Sottas disease and identified two novel mutations in the PMP22 gene: one a 2-bp deletional mutation at nucleotide positions 426 and 427 of exon 4 (this is predicted to alter the reading frame at leucine 80 and thus to lead to frame-shifted translation), and the other a guanine to thymine substitution at nucleotide position 636 leading to a cysteine substitution for glycine 150. Both mutations were located in the putative transmembrane domains reported in many cases of Charcot-Marie-Tooth neuropathy, Dejerine-Sottas disease, and hereditary neuropathy with liability to pressure palsies. The results suggest an important role for the putative transmembrane domains of PMP22 in its function.

Adult↗
PubMed1998

Brain SPECT imaging using three different tracers in subacute cerebral infarction.

Two patients with subacute cerebral infarction underwent benzodiazepine receptor imaging using I-123-iomazenil and cerebral perfusion imaging with Tc-99m HMPAO and Tc-99m ECD. Iomazenil early images resembled HMPAO images, which demonstrated increased uptake in a part of the infarcted site. Iomazenil delayed images and ECD images showed reduced accumulation in the same area. Crossed cerebellar diaschisis was observed in HMPAO, ECD, and iomazenil early images, but it was not remarkable in iomazenil delayed images. These cases suggest that sequential iomazenil images visualized increased uptake with relatively impaired viability in the infarcted site and hypoperfusion with preserved viability in the contralateral cerebellar hemisphere, which could not be recognized without using both HMPAO and ECD in the subacute phase of cerebral infarction.

Adult↗
PubMed1998

Changes in benzodiazepine receptor binding detected with SPECT in patients with cerebral infarction.

SPECT (single photon emission computed tomography) using iomazenil (IMZ) as a ligand for benzodiazepine receptors has recently been developed. Feasibility of the technique for detecting neuronal damage in the cerebral cortex was evaluated in 17 patients with cerebral infarction, specifically, patients with internal carotid artery (ICA) thrombosis (n = 6), middle cerebral artery (MCA) thrombosis (n = 5) and embolism (n = 6). IMZ SPECT was performed 5 to 17 days after stroke. Following the injection of 123I-IMZ 167 or 222 MBq intravenously, images were obtained at 15 minutes (early image) and 180 minutes (late image). In 11 cases, 99mTc-HM-PAO (hexamethyl-propylamine oxime) SPECT was also performed to measure cerebral blood flow (CBF). MRI was performed in all cases to elucidate areas of infarct. Early images from IMZ SPECT correlated well with those from HM-PAO, suggesting that early scans using IMZ SPECT reflect mainly CBF. In late images from IMZ SPECT, observed lesions were consistent with infarcted areas on MRI in most cases. However, in 3 cases of ICA thrombosis, 1 case of MCA thrombosis and 1 case of embolism, late IMZ SPECT imaging showed that the affected area was wider than apparent infarcts on MRI, indicating that the cerebral cortex, which was intact on MRI, was also involved. In these patients, clinical signs of cortical involvement were observed as well. These results suggest that moderately reduced CBF may affect cortical neurons without inducing apparent infarct, and such damage can be detected with IMZ SPECT.

Adult↗
PubMed1998

Fluorometric measurement of intracellular pH in vivo in feline cerebral cortex during ischemia and reperfusion.

Intracellular acidosis has been considered to play an pivotal role in the progression of neuronal damage after cerebral ischemia. However, continuous measurement of the intracellular potential of hydrogen (pH) has not been done during and after ischemia. We measured temporal changes in intracellular pH in the feline cerebral cortex in vivo during and after ischemia using a novel fluorescent pH probe, 2',7'-biscarboxyethyl carboxyfluorescein (BCECF). A closed cranial window was installed in the left temporal skull. BCECF acetoxymethyl ester was superfused over the cortex, hydrolyzed and trapped in cortical cells. Intracellular pH was measured utilizing excitation light at 507 nm and fluorescent light at 550.5 nm. Focal cerebral ischemia for 60 minutes was induced by means of middle cerebral artery occlusion. Intracellular pH in the severely ischemic group became significantly acidic (p < 0.01) during ischemia and the acidosis persisted for at least 30 minutes after recirculation. The pH change was not significant in the mildly ischemic group. The severity of ischemia was determined based on the mean transit time, which was calculated from the hemodilution curve obtained by bolus injection of saline. The extent of ischemia was further confirmed pathologically (p < 0.01). The above results suggest that intracellular acidosis resulting from severe ischemia persists even after recirculation.

Animals↗
PubMed1997

Effects of increased extracellular potassium on influx of sodium ions in cultured rat astroglia and neurons.

Membrane depolarization by elevated extracellular K+ concentration ([K+]o) causes rapid Na+ influx through voltage-sensitive Na+ channels into excitable cells. The consequent increases in intracellular Na+ concentration ([Na+]i) and/or [K+]o stimulate Na+,K+-ATPase activity, which in turn stimulates energy metabolism and rates of glucose utilization (CMR[glc]) in neurons. We previously reported that in cultured cells elevated [K+]o stimulated CMR(glc) in neurons but not astroglia; but increasing [Na+]i by opening voltage-sensitive Na+ channels with veratridine stimulated CMR(glc) in both. These results indicated that Na+ influx plays a key role in the regulation of energy metabolism in neurons and astroglia, but that depolarization of astroglial membranes by elevated [K+]o does not open voltage-sensitive Na+ channels as it does in neurons. To examine this possibility directly we have measured the effects of increased [K+]o and of veratridine on Na+ influx into cultured rat astroglia and neurons. Cells were incubated in bicarbonate buffer containing ouabain (1 mM), tracer amounts of 22NaCl, and various concentrations (5.4, 28, 56 mM) of K+ or 75 microM veratridine for 0-60 min. Cells were digested and assayed for intracellular 22Na+ content. Elevated extracellular K+ stimulated tetrodotoxin-sensitive 22Na+ accumulation in cultured neurons but inhibited 22Na+ influx in astroglia. Veratridine-stimulated Na+ influx in both astroglia and neurons (144% and 133%, respectively), and these effects were completely blocked by 10 microM tetrodotoxin. These results indicate that increased [K+]o does not open voltage-sensitive Na+ channels and may inhibit Na+ influx in astroglia.

Animals↗
PubMed1997

Immunohistochemical detection of nitrotyrosine in postischemic cerebral cortex in gerbil.

We examined whether or not nitration of tyrosine residues takes place in the ischemic and postischemic reperfused brain. The nitration of tyrosine residues to produce nitrotyrosine is a sensitive marker elicited by peroxynitrite, a powerful oxidant formed by the reaction of nitric oxide (NO) with superoxide. Mongolian gerbils were subjected to 60 min ischemia induced by occlusion of the right common carotid artery (ischemia group), to 30 min recirculation following 60 min ischemia (reperfusion group) or to sham surgery (sham group). Immunohistochemical staining with polyclonal anti-nitrotyrosine antibody revealed the widespread and distinct occurrence of nitrotyrosine in cortical neurons on the reperfused side of the brain in the reperfusion group, while only partial or weak immunoreactivity was noted on the contralateral side. On the other hand, nitrotyrosine was not detected in the brain of the ischemia and sham groups. These findings suggest that nitration of tyrosine residues in various proteins may be closely associated with reperfusion injury of the brain.

Animals↗
PubMed1997

Acute ischemic vulnerability of PKA in the dendritic subfields of the hippocampus CA1.

Alterations of [3H]cyclic AMP (cAMP) binding, an indicator of the binding activity of particulate cyclic AMP-dependent protein kinase (PKA), were examined after 15 and 30 min of ischemia in the gerbil brain. Severe hemispheric cerebral ischemia was induced by occluding the right common carotid artery. Significant reductions in cAMP binding were noted only in the dendritic subfields of the hippocampus CA1 such as the strata oriens, radiatum and lacunosum-moleculare, on the ischemic side after 15 min of ischemia. After 30 min ischemia cAMP binding was significantly decreased not only in each dendritic subfield of the hippocampus CA1, but also in the layer of pyramidal cell bodies (stratum pyramidale) on the occluded side; other brain regions such as the hippocampus CA3, dentate gyrus and cerebral cortices revealed no significant changes in cAMP binding. These findings suggest that derangement of PKA may begin in the dendritic subfields of the hippocampus CA1 after as little as 15 min of severe ischemia, and proceed centrally to the neuronal cell bodies of the hippocampus CA1.

Animals↗
PubMed1997

Cerebral hemodynamics in patients with moyamoya disease and in patients with atherosclerotic occlusion of the major cerebral arterial trunks.

To determine the difference in cerebral hemodynamics between Moyamoya disease and atherosclerotic occlusion of the major cerebral arterial trunks, we measured local cerebral blood flow (CBF) and local CO2 reactivity (CO2R) by xenon-enhanced computed tomography (CT). A total of 11 adult patients with Moyamoya disease (mean age, 39.6 +/- 7.8 years) and eight patients with atherosclerotic occlusion of the major arterial trunks (mean age, 62.4 +/- 15.4 years) were studied. Regions of interest were frontal, temporal and occipital cortex, caudate, putamen and thalamus in each hemisphere. In patients with Moyamoya disease, local CBF values in the internal carotid artery territory (frontal and temporal cortex, caudate, putamen) were significantly higher than those in the occluded side of patients with atherosclerotic occlusion. Local CO2R values in the caudate and putamen were significantly higher than those in the occluded side of patients with atherosclerotic occlusion. These results suggest that the cerebral hemodynamics of Moyamoya disease differ from those of atherosclerotic occlusion of the major cerebral arterial trunks, and may be a result of the abundant collateral circulation through basal 'Moyamoya' vessels.

Adult↗
PubMed1997

Calcineurin inhibitor, FK506, prevents reduction in the binding capacity of cyclic AMP-dependent protein kinase in ischemic gerbil brain.

We examined the effects of FK506, a specific inhibitor of calcineurin, on the binding capacity of cyclic AMP-dependent protein kinase (cAMP-DPK) in gerbils subjected to 2-h cerebral hemispheric ischemia. FK506 (0.1 mg/kg) was infused intravenously at 15 min prior to the induction of ischemia by common carotid artery occlusion. The binding capacity of cAMP-DPK was evaluated by autoradiographic analysis of the cAMP binding, and cerebral blood flow (CBF) was measured by the [14C] iodoantipyrine method. In the sham-operated gerbils. FK506 significantly increased mean arterial blood pressure and tended to decrease CBF, suggesting that FK506 may constrict systemic blood vessels as well as cerebral blood vessels. On the other hand, cAMP binding was not altered by FK506 in the sham-operated gerbils. In the ischemia group of gerbils, FK506 prevented any significant reduction of cAMP binding in the hippocampus CA1 and cerebral cortices on the ischemic side, whereas it exerted no significant influence on the cAMP binding of the nonischemic side. The values of CBF were comparable between the vehicle-treated gerbils and FK506-treated gerbils in the ischemic regions. Preservation of cAMP binding indicates that intracellular signal transduction via cAMP-DPK can be maintained by FK506 despite ischemia, suggesting that this agent may be beneficial for reducing ischemic tissue damage.

Animals↗
PubMed1997

Prognostic value of admission blood pressure in patients with intracerebral hemorrhage. Keio Cooperative Stroke Study.

BACKGROUND AND PURPOSE: Patients with acute stroke on admission to the hospital are often found to have high blood pressure. The purpose of the present study was to investigate the prognostic value of admission blood pressure in patients with acute intracerebral hemorrhage, including putaminal, thalamic, subcortical, cerebellar, and pontine hemorrhage. METHODS: A total of 1701 patients with intracerebral hemorrhage of the putamen (n = 776; mean +/- SD age, 58 +/- 14 years) thalamus (n = 538; 63 +/- 12 years), subcortex (n = 153; 61 +/- 16 years), cerebellum (n = 110; 64 +/- 11 years), and pons (n = 124; 59 +/- 13 years) were examined. The mean blood pressure on admission in patients with a fatal outcome was compared with that in patients who survived. RESULTS: The mean age in each patient group (putaminal, thalamic, subcortical, cerebellar, and pontine hemorrhage) with fatal outcome was older than that with nonfatal outcome, while ANCOVA indicated no correlation between age and blood pressure on admission or age and volume of hematoma. The mean arterial blood pressure on hospital admission was 126.9 +/- 25.8 mm Hg (+/-SD) in cases of putaminal. 127.4 +/- 22.6 mm Hg in thalamic, 116.4 +/- 20.6 mm Hg in subcortical, 123.5 +/- 23.9 mm Hg in cerebellar, and 133.0 +/- 26.0 mm Hg in pontine hemorrhage. The mean blood pressure on admission in patients with a fatal outcome among those with putaminal (136.0 +/- 36.3 mm Hg) and thalamic (133.2 +/- 22.1 mm Hg) hemorrhage was significantly higher than that in those with a nonfatal outcome (123.8 +/- 20.6 mm Hg for putaminal, 101.6 +/- 22.5 mm Hg for thalamic) (P < .01). No correlation between mean blood pressure and outcome was observed in the patients with subcortical (116.5 +/- 22.2 mm Hg for nonfatal, 114.9 +/- 22.0 mm Hg for fatal outcome), cerebellar (125.2 +/- 22.2 mm Hg, 116.9 +/- 28.8 mm Hg), and pontine (129.9 +/- 23.8 mm Hg, 136.0 +/- 27.7 mm Hg) hemorrhage. The volume of hematoma on admission in patients with fatal outcome with putaminal (58.2 +/- 24.4 mL), thalamic (27.0 +/- 13.1 mL), subcortical (32.9 +/- 14.4 mL), and cerebellar (31.4 +/- 28.6 mL) hemorrhage was greater than that in those with nonfatal outcome (20.8 +/- 11.4 mL, 7.1 +/- 4.8 mL, 18.3 +/- 10.6 mL, and 8.1 +/- 4.2 mL, respectively; P < .01), while no correlation between volume of hematoma and outcome was observed in patients with pontine hemorrhage. CONCLUSIONS: The above data suggest that an increased mean blood pressure and volume of hematoma on admission in putaminal and thalamic hemorrhage were related to increased mortality, while in patients with subcortical, cerebellar, and pontine hemorrhage, the mean blood pressure was not related to the clinical outcome.

Age Factors↗
PubMed1997

Familial idiopathic brain calcification with autosomal dominant inheritance.

We report a family with brain calcification, predominantly in the basal ganglia, and no evident cause such as abnormal calcium or phosphorus metabolism. The proband, a 48-year-old man, had intellectual decline, parkinsonism, and mild cerebellar ataxia. He had bilateral and symmetric calcification of the basal ganglia, thalamus, dentate nucleus, cerebral cortex, subcortical white matter, and hippocampus on CT. Calcified areas showed low- or high-intensity signals on MRI T1-weighted images, and low-intensity signals on MRI T2-weighted images. Two sons and both parents, all asymptomatic, also showed calcification of the basal ganglia, suggesting an autosomal dominant inheritance. Familial idiopathic brain calcification is a rare disorder with less than 20 previously reported families. Twelve families with autosomal dominant inheritance showed a relatively homogeneous clinical picture, which may represent a distinct clinical entity. Mental deterioration, parkinsonism, and cerebellar ataxia appear in adult life and progress gradually. CT imaging, rather than MRI, is a simple and useful means to screen family members for this condition.

Brain Diseases↗
PubMed1997

Rapid changes in pial arterial diameter and cerebral blood flow caused by ipsilateral carotid artery occlusion in rats.

We investigated rapid changes in pial arterial diameter and in cerebral blood flow (CBF) caused by transient ipsilateral common carotid artery occlusion (CCA-O) in anesthetized rats in order to elucidate how the cerebral circulation reacts to acute stem artery occlusion. In separate groups of rats, pial arterial diameter was recorded through a closed cranial window and CBF was recorded by laser-Doppler flowmetry. CCA-O was performed for 5 minutes under normotension and normocapnia (control) and under graded hypotension, hypercapnia and hypocapnia. In the control condition, pial arterial diameter increased rapidly, triggered by CCA-O. It took 12 +/- 3 s to reach the maximum of 204 +/- 42% of the value before CCA-O, and 60 +/- 24 s to become stable at 131 +/- 11%. CBF decreased rapidly to 66 +/- 11%, then increased reactively to 135 +/- 9%, and again decreased to 91 +/- 3%. The reactive increase in CBF caused by CCA-O decreased in parallel with the degree of hypotension, and also became barely detectable under hypercapnia. Our data suggest that active vascular dilation in the territory of the occluded artery is important for inducing collateral circulation.

Animals↗
PubMed1997

Rapid reduction in ryanodine binding of hippocampus CA1 in cerebral ischemia.

Ryanodine receptors located on the sarcoplasmic or endoplasmic reticulum, play an important role in the regulation of the intracellular Ca2+ level via the mechanism of Ca(2+)-induced Ca2+ release (CICR). Perturbation of intracellular Ca2+ regulation has been considered to be one of the most important mechanisms underlying acute ischemic neuronal damage. The ryanodine binding, an indicator of intracellular channels of CICR, and local cerebral blood flow (LCBF) were therefore examined at 15 min post-ischemia in the gerbil brain. The autoradiographic method developed in our laboratory enabled us to determine both parameters within the same brain. Severe hemispheric cerebral ischemia was induced by occluding the right common carotid artery. LCBF was measured at the end of the experiment using [14C]iodoantipyrine method. The ryanodine binding was evaluated autoradiographically in vitro using [3H] ryanodine. A group of gerbils who underwent a sham procedure served as controls. LCBF was found to be significantly decreased in most cerebral regions on the occluded side. In contrast, a significant reduction in ryanodine binding was noted only in the hippocampus CA1 on the occluded side. Taken together, these findings indicate that the CICR in the hippocampus CA1 may be especially susceptible to acute ischemic stress, and be closely associated with the pathophysiological mechanisms of the selective vulnerability of this region.

Animals↗