Biomedical subjects

T Yanagihara

Publications and source records attributed to T Yanagihara.

At least 109 records · Page 6Linked to original sources

PubMed1998

Immunohistochemical and urinary markers of podocyte injury.

Renal podocytes play an important role in glomerular filtration. We estimated podocyte injury by light microscopic examination of kidney specimens or by urinary excretion of substances related to podocytes. Fresh kidney sections from 69 patients and urinary sediments from 84 patients with various renal diseases were examined immunohistochemically using fluorescent labelling. Four kinds of monoclonal antibodies which recognize podocytes were used: (1) anti-podocalyxin (anti-PCX) antibody, (2) anti-C3b receptor (anti-C3bR) antibody, (3) anti-podocyte protein, 44 kilodalton, (anti-pp44) antibody, and (4) anti-alpha 3 integrin (anti-Int alpha3) antibody. Labelling of kidney sections by anti-C3bR (k-C3bR) was reduced in cases of severe glomerular injury, although there were no changes in k-PCX, k-pp44, or k-Int alpha3 labelling. PCX labelling of urinary sediments (u-PCX) was detected in nearly all cases of glomerulonephritis, u-C3bR was seen in some cases of glomerular injury, u-Int alpha3 was seen in only a small number of cases of severe glomerular injury, and u-pp44 was not detected in any urinary samples. u-PCX, u-C3bR, u-Int alpha3, and k-C3bR correlated with the degree of pathological change, the degree of proteinuria and hematuria. These results suggest that immunostaining kidney sections with anti-C3bR antibody and urinary sediments with anti-PCX, anti-C3bR, and anti-Int alpha3 antibodies might be useful in detecting podocyte injury.

Adolescent↗

PubMed1998

Separation and characterization of carboxyl-linked glucuronides of bile acids in incubation mixture of rat liver microsomes.

The carboxyl-linked 24-glucuronides of common bile acids have been identified by means of liquid chromatography (LC)/atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) in an incubation mixture with a male Wistar rat liver microsomal fraction. The authentic specimens of bile acid 24-glucuronide acetate-methyl esters were synthesized unequivocally using the Mitsunobu reaction, and the APCI-mass spectrometric properties of these glucuronide derivatives were also characterized. After incubation of common unconjugated bile acids with hepatic microsomes, glucuronides were extracted and purified with a Sep-Pak C18 cartridge and lipophilic ion exchange gel, piperidino-hydroxypropyl Sephadex LH-20, and then derivatized into the acetate-methyl esters. Subsequent resolution into alpha- and beta-isomers at the glucuronosyl linkage was attained by LC on Cosmosil 5C8 and Sumichiral OA-2500 columns using 200 mM ammonium acetate (pH 7.0)-methanol (1:4, v/v), where 24-glucuronides were monitored with characteristic positive ions [M + NH4]+. The 24-glucuronides of lithocholic, chenodeoxycholic, deoxycholic, ursodeoxycholic and cholic acid were definitely characterized, in contrast to no formation of corresponding 3-glucuronides.

Animals↗

PubMed1998

Fas has a crucial role in the progression of experimental autoimmune encephalomyelitis.

To investigate the role of Fas in experimental autoimmune encephalomyelitis (EAE) in mice, we examined the susceptibility of EAE in C57BL/6 (B6).lpr mice lacking Fas. The frequency of myelin oligodendrocyte glycoprotein (MOG)-induced EAE in B6.lpr mice was significantly lower than that in B6 mice (19% vs 94%). However, no significant difference was observed between them in either the lymphocyte proliferation response or antibody reactivity to MOG. In addition, the histological examination and semiquantitative reverse transcriptase polymerase chain reaction analysis revealed that the infiltration of inflammatory cells and the up-regulation of gene expression for inflammatory cytokines occurred in the central nervous system (CNS) of B6.lpr mice immunized with MOG, even if they showed no clinical sign. These results indicate that Fas may contribute to the pathogenesis of EAE and may play a crucial role in the expansion of inflammation and/or myelin destruction in the CNS rather than in the activation of encephalitogenic T cells in the periphery and/or the breakdown of blood brain barrier.

Animals↗

PubMed1998

Aminoguanidine, a selective inhibitor of the inducible nitric oxide synthase, has different effects on experimental allergic encephalomyelitis in the induction and progression phase.

To elucidate the role of excessive nitric oxide (NO) via the inducible nitric oxide synthase (iNOS) in experimental allergic encephalomyelitis (EAE), the effect of a selective iNOS inhibitor, aminoguanidine, was investigated using mice with actively induced EAE. Administration of aminoguanidine by intraperitoneal or intracisternal injection from day 2 to day 12 after immunization produced a significant delay in the onset of EAE. On the other hand, administration of aminoguanidine by intraperitoneal or intracisternal injection for 10 days after the onset of EAE enhanced the clinical severity and mortality rate and hastened the onset of relapse significantly. The histological study at day 11 after the onset revealed that more inflammatory cells were present in the central nervous system of mice treated with aminoguanidine as compared with mice without aminoguanidine treatment. These results suggested that NO via iNOS was a pathogenetic factor in the induction phase of EAE, but had an inhibitory role in the progression phase of EAE. Although the effect of NO synthase inhibitors on EAE has been controversial, the present study suggested that the timing of administration might be an important consideration and might explain the previous contradictory reports.

Acute Disease↗

PubMed1998

Brainstem auditory evoked potentials during brainstem ischemia and reperfusion in gerbils.

To evaluate the reversibility of neural function in the brainstem following ischemia, we investigated the effect of transient brainstem ischemia on the brainstem auditory evoked potential in gerbils. Brainstem ischemia was produced by bilateral extracranial occlusion of vertebral arteries. Local cerebral blood flow was measured by quantitative autoradiography after 5 min of ischemia and was reduced to less than 3 ml/100 g per min in the pons and lower midbrain, indicating severe and reproducible brainstem ischemia. During brainstem ischemia, brainstem auditory evoked potential waveforms disappeared completely. After a brief ischemic insult (5 min), all four brainstem auditory evoked potential components recovered to normal. After longer ischemic insults (10-30 min), brainstem auditory evoked potential components never recovered to normal. Microtubule-associated protein 2 immunoreactivity revealed differential vulnerability of the acoustic relay nuclei in the brainstem. Neurons in the lateral lemniscus were most vulnerable, followed in order by neurons in the trapezoid body, the superior olive and the cochlear nucleus. We also demonstrated a close relationship between the reversibility of ischemia-induced changes on brainstem auditory evoked potential and ischemic lesions of these relay nuclei. These data may be useful for evaluating the therapeutic window of thrombolytic therapy during acute vertebrobasilar occlusion.

Animals↗

PubMed1998

Alterations of Bcl-2 family proteins precede cytoskeletal proteolysis in the penumbra, but not in infarct centres following focal cerebral ischemia in mice.

Apoptosis has drawn attention in ischemic neuronal death recently. However, studies of apoptosis in cerebral ischemia have concentrated largely in DNA fragmentation, a late phase in apoptotic nuclei, at the expense of possible primary ischemic targets at the subcellular level and of upstream apoptotic signalling. To assess those issues, we used an intraluminal middle cerebral artery occlusion model in mice with or without reperfusion, and examined sequential changes of Bcl-2 family proteins modulating apoptotic signalling immunohistochemically and studied nuclear DNA fragmentation, to compare their chronology in relation to the development of infarct as detected by loss of microtubule-associated protein-2, an early marker of cytoplasmic damage. In the centre of the lesion, Bax protein increased and Bcl-2 and Bcl-x proteins decreased after loss of microtubule-associated protein-2 antigenicity occurred, but at the border of the lesion, the former changes preceded loss of microtubule-associated protein-2 antigenicity. Additionally, close morphologic analysis of DNA fragmentation in situ indicated that transient ischemia predominantly induced apoptotic cells but permanent ischemia produced necrosis of cells in the centre of the lesion. The contrasting cell death mechanisms, apoptosis and necrosis, are selectively involved in the pathology of cerebral ischemia, depending on its severity.

Animals↗

PubMed1998

Three-dimensional ultrasonographic assessment of fetal hands and feet.

OBJECTIVE: The aim of this study was to describe fetal hands and feet using three-dimensional ultrasonography. DESIGN: This was a randomized prospective study. METHODS: Ninety-seven fetuses from 12 to 40 weeks' gestation were studied with a specially developed trans-abdominal three-dimensional transducer (3.5 MHz). The imaging system used in this study can provide conventional two-dimensional ultrasound images and can also generate, within seconds, high-quality three-dimensional images in the surface and transparent modes with no need for an external workstation. The rate of visualization of the hands/fingers and feet/toes at each gestational-age interval was calculated using two-dimensional and three-dimensional ultrasonography. RESULTS: The ability to visualize fetal hands/fingers and feet/toes was better with three-dimensional than with two-dimensional ultrasonography in the late first trimester (detection rates were 65% and 41% by three-dimensional ultrasonography for hands and feet, respectively, and 41% and 12%, respectively, by two-dimensional ultrasonography). For the early second trimester, detection rates were 82% for hands and 72% for feet by three-dimensional ultrasonography, and 54% for hands and 45% for feet by two-dimensional ultrasonography. Optimal visualization of the fetal fingers using three-dimensional ultrasonography was achieved between 28 and 35 weeks of gestation, although at this stage there were no significant differences in detection rates for hands and feet between two- and three-dimensional imaging. During this period it was possible with three-dimensional ultrasonography adequately to depict at least one hand in 93% of the fetuses at 28-31 weeks and in 88% at 32-35 weeks. The percentage of visualization of at least one fetal foot between 16 and 35 weeks using three-dimensional ultrasonography ranged from 50 to 85%. Before 15 weeks or after 36 weeks, the respective percentages decreased. CONCLUSIONS: Three-dimensional ultrasonography provides a novel means of visualizing fetal fingers and toes. Our observations suggest that three-dimensional ultrasonography may enhance the diagnostic potential of two-dimensional ultrasonography and might be useful in identifying fetal malformations and anatomical markers of chromosomal abnormalities prenatally in high-risk pregnancies.

Embryonic and Fetal Development↗

PubMed1998

Induction of 72-kDa inducible heat shock protein (HSP72) in cultured rat astrocytes after energy depletion.

Protein synthesis is important in the readaptive processes for cultured astrocytes after hypoxia and subsequent reoxygenation. We have identified 72-kDa inducible heat shock protein (HSP72) as a major stress protein in reoxygenated astrocytes. To assess the mechanism for reoxygenation-mediated induction of HSP72, a reporter gene that consists of a human HSP promoter fused to the luciferase gene was transfected into cultured astrocytes. Analysis of cellular energy nucleotides showed an increase of the ADP/ATP ratio after reoxygenation, which synchronized with activation of the HSP promoter. Activation of the HSP promoter was also observed after an addition of iodoacetic acid to hypoxic astrocytes, which reached the maximum when the ADP/ATP ratio reached 50%, but further decline in the energy profile caused inactivation of this promoter. Inhibition of protein synthesis after reoxygenation resulted in temporary restoration of the energy profile and suppression of the DNA binding activity of the heat shock factor. Addition of quercetin greatly decreased the [3H]leucine incorporation in the polysome fraction without any effect on the mature mRNA formation. These data suggest that the energy depletion in reoxygenation triggers induction of HSP72 after reoxygenation, which may act as a pivotal mediator in the stress response of reoxygenated astrocytes by facilitating protein synthesis.

Adenine Nucleotides↗

PubMed1998

Functional characterization of renal chloride channel, CLCN5, mutations associated with Dent'sJapan disease.

BACKGROUND: The annual urinary screening of Japanese children above three years of age has identified a progressive renal tubular disorder characterized by low molecular weight proteinuria, hypercalciuria and nephrocalcinosis, and this represents a variant of Dent's disease. Hitherto, 12 mutations of the X-linked renal specific chloride channel, CLCN5, have been reported in the Dent'sJapan variant. To further identify such CLCN5 mutations and to define the structure-function relationships of this channel, we have investigated five unrelated, non-consanguinous Japanese families with this disorder. METHODS: Leukocyte DNA from probands was used with CLCN5 primers for PCR amplification of the coding region, and the DNA sequences of the products determined. Functional studies were performed by expressing the mutants in Xenopus oocytes. RESULTS: Five CLCN5 mutations consisting of two nonsense (R648X and R704X), two missense (S270R and L278F) and one acceptor splice site mutation (ag-->cg) in intron 4 were identified. The missense and splice site mutations represent novel abnormalities. Heterologous expression in Xenopus oocytes of wild-type and the missense mutants demonstrated that the mutations, which were translated, either abolished or markedly reduced chloride conductance. CONCLUSIONS: These results expand the spectrum of CLCN5 mutations associated with this renal disorder and provide insight into possible structure-function relationships. For example, both the missense mutations are located within a short putative loop between two transmembrane domains, and our results suggest that this region may have an important functional role in the regulation of channel activity.

Adolescent↗

PubMed1998

The development of autoimmune encephalomyelitis provoked by myelin oligodendrocyte glycoprotein is associated with an upregulation of both proinflammatory and immunoregulatory cytokines in the central nervous system.

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system (CNS). We previously reported upregulation of gene expression for a number of proinflammatory cytokines, interleukin-1beta (IL-1beta), IL-2, IL-6, tumor necrosis factor-alpha (TNF-alpha), TNF-beta, and interferon-gamma (IFN-gamma), in the CNS of mice with myelin basic protein (MBP)-induced relapsing EAE by using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). However, in these mice there was no significant increase of gene expression for immunoregulatory cytokines (IL-4, IL-10, transforming growth factor-beta [TGF-beta]). We report here that gene expression for both proinflammatory and immunoregulatory cytokines increased during the course of disease in the CNS of mice with myelin oligodendrocyte glycoprotein (MOG)-induced nonrelapsing EAE. These results indicate that the gene expression pattern of immunoregulatory cytokines in the CNS may be different between MBP-induced and MOG-induced EAE and that it may influence the type of disease. Accordingly, the course of the disease may be influenced by the interplay between the proinflammatory and immunoregulatory cytokines.

Animals↗

PubMed1998

IL-6-deficient mice are resistant to the induction of experimental autoimmune encephalomyelitis provoked by myelin oligodendrocyte glycoprotein.

The role of IL-6 in experimental autoimmune encephalomyelitis (EAE) provoked by myelin oligodendrocyte glycoprotein (MOG) was investigated using IL-6-deficient mice. We show here that IL-6-deficient mice were resistant to the MOG-induced EAE as compared to wild-type mice (one out of 18 versus 17 out of 20). The delayed-type hypersensitivity response, lymphocyte proliferation response and antibody reactivity to MOG in IL-6-deficient mice were significantly lower than those in wild-type mice. Furthermore, the histological examination revealed that no infiltration of inflammatory cells was observed in the central nervous system of IL-6-deficient mice. These results indicate that IL-6 may play a crucial role in the induction phase of EAE. Given the potential relevance of this animal model for multiple sclerosis (MS), it is possible that anti-IL-6 therapy may be useful in the prevention of relapses of MS.

Animals↗

PubMed1998

Cerebral ischemia after bilateral carotid artery occlusion and intraluminal suture occlusion in mice: evaluation of the patency of the posterior communicating artery.

Cerebral ischemia models using mice have drawn increasing attention, particularly because of the availability of transgenic animals. However, the variability of intracranial vasculature at the circle of Willis in mice can influence the degree of ischemia in both the bilateral common carotid artery (CCA) occlusion and intraluminal suture occlusion models. We have developed a method to predict the extent of the anastomosis between carotid and vertebrobasilar circulation in three mouse strains (C57BL/6, CBA, and DBA/2) by measuring cortical microperfusion with laser Doppler flowmetry during a 1-minute occlusion of both CCA. When animals showed residual cortical microperfusion of less than 12% during bilateral CCA occlusion, the mice showed absence of functional anastomosis, developed ATP depletion in the frontal cortex during occlusion, and had ischemic neuronal death in the hippocampus and caudoputamen after occlusion for 15 minutes and recirculation for 7 days. Furthermore, those mice exhibited decreased local cerebral blood flow and associated ischemic neuronal death in the hippocampus, within the territory supplied by the posterior cerebral artery, with the intraluminal suture occlusion model. The current study demonstrates the need for assessment of intracranial vasculature in each animal by measuring cortical microperfusion during temporary occlusion of both CCA, no matter whether cerebral ischemia is produced by bilateral CCA occlusion or intraluminal suture occlusion in transgenic mice.

Animals↗

PubMed1998

Deficiency of intercellular adhesion molecule 1 attenuates microcirculatory disturbance and infarction size in focal cerebral ischemia.

Recent evidence has shown crucial roles for cell-adhesion molecules in inflammation-induced rolling, adhesion, and accumulation of neutrophils in tissue. Intercellular adhesion molecule-1 (ICAM-1) is one of these adhesion molecules. Previous studies have shown marked reduction in the size of infarction after focal cerebral ischemia by depletion of granulocytes and administration of the antibody against ICAM-1. In the present study we investigated the role of ICAM-1 in the size of ischemic lesions, accumulation of granulocytes, and microcirculatory compromise in focal cerebral ischemia by using ICAM-1-knockout mice. Ischemic lesions were significantly mitigated in knockout mice after permanent and transient focal ischemia, even though the number of granulocytes in the infarcted tissue was almost the same between knockout and wild-type mice. Depletion of granulocytes further decreased the size of ischemic lesions after transient focal ischemia in ICAM-1-knockout mice. Microcirculation was reduced after focal ischemia, but it was better preserved in the cerebral cortex of knockout mice than that of wild-type mice. The present study demonstrated that ICAM-1 played a role in microcirculatory failure and subsequent development and expansion of infarction after focal cerebral ischemia. However, it is highly unlikely that ICAM-1 played a key role in accumulation of granulocytes after focal cerebral ischemia.

Animals↗

PubMed1998

Retinocochleocerebral vasculopathy.

We report 10 patients with retinocochleocerebral vasculopathy and review the clinical and diagnostic considerations in previously reported patients with this uncommonly recognized disease. The clinical manifestations include acute and subacute multifocal and diffuse encephalopathic symptoms, hearing loss, and visual loss attributable to microangiopathy affecting the arterioles of the brain, retina, and cochlea. Diagnosis is facilitated by demonstration of retinal arteriolar occlusions without uveitis or keratoconjunctivitis, mid- to low-frequency unilateral or bilateral sensorineural hearing loss, and numerous small foci of increased signal in the white and gray matter on T2 weighted brain magnetic resonance imaging. Because many conditions may produce any combination of strokelike cerebral symptoms, encephalopathy, hearing loss, and visual loss, the differential diagnosis for retinocochleocerebral vasculopathy includes connective tissue disease, demyelinating disease, procoagulant state, infection, neoplasm, and more routine mechanisms of cerebral and retinal ischemia. Brain biopsy specimens demonstrate only minimal nonspecific periarteriolar chronic inflammatory cell infiltration with or without microinfarcts. The demonstration of subclinical arteriolar microangiopathy in muscle biopsy specimens, documented in 3 of our patients may assist in making the diagnosis. The clinical course appears to be monophasic. In addition to corticosteroids, treatment options include immunosuppressant agents (cyclophosphamide or azathioprine) aspirin, calcium channel blockers (nimodipine), intravenous immunoglobulin, and plasmapheresis. The etiology of the disease is unknown, but histopathologic and laboratory evidence suggests that an immune-mediated mechanism may be involved.

Adolescent↗

PubMed1998

Effects of sex steroids and growth factors on invasive activity and 5'-deoxy-5-fluorouridine sensitivity in ovarian adenocarcinoma OMC-3 cells.

Effects of sex steroids (estradiol-17 beta, E2; progesterone, Prog) and growth factors (epidermal growth factor, EGF; transforming growth factor-alpha, TGF-alpha) on invasive activity and 5'-deoxy-5-fluorouridine (5'-dFUrd) sensitivity of ovarian adenocarcinoma OMC-3 cells were investigated. Tumor cell migration along a gradient of substratum-bound fibronectin and invasion into reconstituted basement membrane were inhibited by 10 microM Prog, but stimulated by 0.1-10 nM EGF and TGF-alpha in a concentration-dependent manner. E2 did not have any effect on tumor cell migration or invasion. The zymography of tumor conditioned medium showed that the treatment of OMC-3 cells with EGF and TGF-alpha resulted in increases of type IV collagenase, stromelysin and urokinase-type plasminogen activator (uPA). EGF and TGF-alpha up-regulated thymidine phosphorylase (dThdPase) expression of tumor cells and consequently enhanced the antiproliferative action of 5'-dFUrd, which is converted to 5-fluorouracil by dThdPase. E2 and Prog did not have significant effects on the expression of proteolytic enzymes and dThdPase, or on the 5'-dFUrd sensitivity of tumor cells. The inhibitory effect of Prog on tumor cell invasion may depend on its inhibitory action on the motility of tumor cells. These results suggest that EGF and TGF-alpha simultaneously up-regulate the potential of ovarian adenocarcinoma cells to invade extracellular matrices and their dThdPase expression, both of which are associated with the specific action of 5'-dFUrd selectively to kill tumor cells with high invasive and metastatic potential.

Basement Membrane↗

PubMed1998

Amnesia after a discrete basal forebrain lesion.

Destructive lesions of the basal forebrain are often associated with memory impairment and this structure is thought to contribute to memory function by providing a cholinergic input to critical structures associated with memory such as the hippocampus and amygdala. In previously reported cases of amnesia associated with damage in the basal forebrain, multiple neuroanatomical regions were damaged, and the critical lesion responsible for amnesia has not been identified clearly. We report a patient who developed primarily anterograde amnesia after clipping of an unruptured anterior communicating artery aneurysm. Postoperative magnetic resonance imaging showed a discrete lesion, centering in the right diagonal band of Broca and including the anterior hypothalamus, septal nucleus, lamina terminalis, and paraterminal gyrus, and an indiscrete patchy lesion in the corresponding area on the opposite side. The nucleus basalis of Meynert was minimally affected and the diencephalon was not damaged. Single photon emission computed tomography showed marked hypoperfusion in the midline frontobasal region corresponding to the MRI lesion and hypoperfusion in the hippocampus bilaterally. It is concluded that disconnection of the pathway between the diagonal band of Broca and the hippocampus contributed to memory impairment.

Amnesia↗

PubMed1998

Urinary excretion of podocytes reflects disease activity in children with glomerulonephritis.

The significance of the presence of podocytes in the urine was studied in various renal diseases in children. The podocytes were detected by immunofluorescence using monoclonal antibodies against the podocalyxin that is present on the surface of podocytes which serves as a glycocalyx. They were scored according to the numbers per partitioned area on cytospun urine sediments. Urine podocytes were absent in normal control, nonglomerular diseases such as urinary tract infection and nonglomerular hematuria, and glomerular, non-inflammatory diseases such as minimal change nephrotic syndrome and membranous nephropathy. Conversely, the excretion of podocytes in the urine were detected in various glomerular, inflammatory diseases. A significantly higher level of the podocyte score was found in the acute state of glomerular diseases which was defined as within 6 months after disease onset. Positive correlations were obtained between the presence of urinary podocytes and the histological features of active extracapillary changes and mesangial proliferation. Urinary podocytes were examined monthly for 12 months in 7 cases with IgA nephropathy and 2 cases with Henoch-Schönlein purpura nephritis, and a consistently higher urinary podocyte score was observed in the patients with histological progression. The scoring of urinary podocytes was found to be useful clinically, as a diagnostic tool for glomerular or nonglomerular diseases, inflammatory or noninflammatory diseases, a marker for the estimation of the severity of active glomerular injury and also as a predictor of disease progression.

Adolescent↗

PubMed1998

Glomerular injuries--excretion of glomerular epithelial cells-- induced by chemotherapy (antineoplastic drugs) independent of tubular damage.

For the purpose of studying glomerular injuries induced by antineoplastic drugs, the excretion of glomerular epithelial cells (GEC) was evaluated. In 13 children who received antineoplastic drugs, the excretion of GEC in urine samples was examined with an immunofluorescent study using a monoclonal antibody directed against podocalyxin, which was expressed on glomerular epithelial cells. GEC were detected in 20 of 25 chemotherapy courses. The excretion of GEC persisted until the next chemotherapy course in some cases. After an initiation of chemotherapy an increased urinary albumin-creatinine ratio (more than 2-fold) was found in 6 patients. A significant increase of N-acetylglucosaminidase was observed in 2 patients. Proteinuria and hematuria were not observed in all patients. These results indicate that glomerular injuries are frequently induced by chemotherapy independent of the tubular damage. Repeated glomerular injuries may result in late renal dysfunction.

Acetylglucosaminidase↗