Search PubMed⌕ Search

Biomedical subjects

Hidehiro Mizusawa

Publications and source records attributed to Hidehiro Mizusawa.

At least 73 records · Page 4Linked to original sources
PubMed2003

Inhibition of intracellular hepatitis C virus replication by synthetic and vector-derived small interfering RNAs.

Small interfering RNAs (siRNAs) efficiently inhibit gene expression by RNA interference. Here, we report efficient inhibition, by both synthetic and vector-derived siRNAs, of hepatitis C virus (HCV) replication, as well as viral protein synthesis, using an HCV replicon system. The siRNAs were designed to target the 5' untranslated region (5' UTR) of the HCV genome, which has an internal ribosomal entry site for the translation of the entire viral polyprotein. Moreover, the 5' UTR is the most conserved region in the HCV genome, making it an ideal target for siRNAs. Importantly, we have identified an effective site in the 5' UTR at which approximately 80% suppression of HCV replication was achieved with concentrations of siRNA as low as 2.5 nM. Furthermore, DNA-based vectors expressing siRNA against HCV were also effective, which might allow the efficient delivery of RNAi into hepatocytes in vivo using viral vectors. Our results support the feasibility of using siRNA-based gene therapy to inhibit HCV replication, which may prove to be valuable in the treatment of hepatitis C.

5' Untranslated Regions↗
PubMed2003

Mutation of the EYA1 gene in patients with branchio-oto syndrome.

Branchio-oto-renal (BOR) and branchio-oto (BO) syndromes are autosomal dominant disorders, characterized by the presence of branchial, otic and renal anomalies of varying degrees of severity. We investigated the presence of EYA1 mutation in two unrelated patients with autosomal dominant hereditary deafness and congenital preauricular fistula. Case 1 had a mutation and polymorphisms, while Case 2 had polymorphisms with no mutations. In Case 1 we detected a heterozygous A-->G mutation at nucleotide 625 resulting in a serine to glycine substitution at codon 189 (S189G). The S189G mutation was not detected in 54 controls (108 alleles). Pure-tone audiometry showed bilateral mixed hearing loss of mild to moderate severity in Case 1. Case 2 had suffered from bilateral hearing loss since the age of 5 years and pure-tone audiometry showed bilateral moderate mixed hearing loss. These results suggest that the S189G mutation is a candidate mutation for BOR/BO syndrome.

Adult↗
PubMed2003

TNF-related apoptosis-inducing ligand (TRAIL) induces neuronal apoptosis in HIV-encephalopathy.

Neuronal loss is, frequently found in brains of patients with human immunodeficiency virus (HIV)-encephalopathy. Extensive apoptosis of neurons is probably involved in the development of HIV-encephalopathy. The present study was designed to investigate the mechanism of neuronal apoptosis. For this purpose, we examined autopsy brains of two patients with HIV-encephalopathy. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells and active forms of caspase-3- and -8-positive cells, including neurons, were found in the perivascular regions of the brains. In these regions, TNF-related apoptosis-inducing ligand (TRAIL)+ macrophages were also observed. We also examined brains of HIV-1-infected mouse model inoculated with human cells. In these brains, TUNEL+ neurons were also found in the perivascular region, the site where infiltrated HIV-1-infected and TRAIL-expressing macrophages were observed. Using an in vitro-culture system, we also demonstrated that the HIV-1-infected monocyte-derived macrophages preferentially expressed TRAIL and that the addition of HIV-1-infected macrophages or human TRAIL-overexpressing mouse cells to cultured mouse primary neurons/glia resulted in neuronal apoptosis. Our results suggest the involvement of TRAIL expressed on HIV-1-infected macrophages in the induction of neuronal apoptosis in infected brain.

AIDS Dementia Complex↗
PubMed2003

[Bilateral medial medullary infarction presented with monoplegia of the lower limb, followed by paraplegia and finally by tetraplegia].

A 69-year-old Japanese man suddenly developed monoplegia of left lower extremity, followed by paraplegia and finally by tetraplegia. MRI revealed an infarction in bilateral medial medulla extending from the cervicomedullary junction up to the upper limit of the medulla. Both hypoglossal nerve palsy and sensory disturbance were absent. At the pyramidal decussation, fibers to the lower extremities cross caudal to the fibers going to the upper extremities, therefore right below the decussation, fibers to the lower extremities run medial side of the fibers to the upper extremities, but later the former run lateral side of the latter. In this patient, the authors considered that the lesion initially damaged the pyramidal decussation at a slightly lower level, involving the tract to left lower extremity, and then extended to right lower extremity, to the left upper extremity, finally to the right upper extremity. Bilateral medial medullary infarction must be considered in the clinical course seen as in this patient.

Cerebral Infarction↗
PubMed2003

[Pneumatosis intestinalis in a patient of myasthenia gravis treated with high-dose corticosteroid].

We report a patient who developed persistent and severe diarrhea in the course of high-dose corticosteroid therapy for myasthenia gravis (MG). The patient, a 37-year-old woman, developed diplopia, ptosis, and muscle weakness with fatigability. She was admitted to our hospital and was diagnosed as having MG. Five months after thymectomy and oral corticosteroid administration, she developed abdominal pain and severe diarrhea. Abdominal X-ray, showed extensive pericolic gas accumulation surrounding the ascending and transverse colon. She was diagnosed as having pneumatosis intestinalis (PI). Hyperbaric therapy was not effective. Symptoms began to improve gradually when the dose of prednisolone was reduced. PI is a rare condition characterized by gas-filled cysts or linear gas in the bowel wall caused by a variety of disorders and drugs such as necrotizing colitis, obstructive pulmonary diseases, and immunosuppressants. In the present case, PI appeared to be induced by corticosteroid therapy. To our knowledge, MG complicated by PI is unusual, but this rare case highlights the importance of taking it into consideration during steroid therapy for MG.

Adult↗
PubMed2003

[Multiple cerebral embolism caused by a patent foramen ovale and a uterine myoma].

Recently, patent foramen ovale(PFO) has been highlighted as an important risk factor of cerebral infarctions in young adults. We report a patient of multiple cerebral embolism associated with PFO and deep venous thrombosis caused by a uterine myoma. A 40-year-old woman suddenly suffered from right hemiparesis with motor aphasia. Brain angiography showed an occlusion of M2 portion of the left middle cerebral artery, but atherosclerotic changes were not seen. She developed left facial paresis 23 days later and admitted to our hospital. Brain MRI revealed multiple cerebral infarcts in the left insular cortex, the deep white matter of the right frontal lobe, and bilateral thalamus. Hypoxia with the perfusion defects of S1 and S2 sections of the right lung demonstrated by scintigraphy suggested pulmonary embolism. Transesophageal echocardiography showed a PFO with spontaneous left-to-right shunt and right-to-left shunt evoked by the Valsalva maneuver. Although venography could not detect thrombi, it revealed severe compression of the right external iliac vein by a uterine myoma. These findings suggested thrombi in the right external iliac vein were the embolic source when combined with elevated coagulation markers. An uterine myoma should be considered as an important risk factor for an embolic source in case of cerebral embolism with PFO.

Adult↗
PubMed2003

[Two distinct types of neuropathy associated with Sjögren's syndrome developed in one patient. The importance of the selection of an appropriate therapeutic regimen].

A 62-year-old woman was admitted to our hospital because of muscle weakness and sensory disturbance in extremities. She showed weakness, muscle atrophy and sensory abnormality in four limbs with patchy distribution, suggesting involvement of multiple peripheral nerve trunks. Serum titers of anti-SS-A, SS-B, and antinuclear antibody were elevated. Sural nerve biopsy showed recanalization and lymphocytic infiltration in the epineural small vessels, suggesting the presence of vasculitis. She was diagnosed as having vasculitic neuropathy complicated with Sjögren's syndrome. Methylprednisolone pulse therapy followed by oral prednisolone was started and these symptoms gradually improved in one month. At age 63, she felt dysesthesia in the right lower limb and this sensory abnormality spreaded to upper limbs. Two years later, she was admitted again due to clumsiness of hands and gait disturbance. Neurological examination showed decreased vibration and position sense of lower limbs and limb ataxia in addition to dysesthesia. Electrophysiological studies demonstrated significant decrease in amplitude of sensory nerve action potentials and delayed somatosensory evoked potentials after N13, indicating impairment of dorsal root ganglions. She was treated with intravenous immunoglobulin (400 mg/kg, total 15 g/day) for 5 days. One week later, sensory ataxia was improved. It has been known that Sjögren's syndrome is often complicate with various types of neuropathies including vasculitic neuropathy and sensory neuropathy. Our patient developed these two different types of neuropathies which were dramatically improved after two different therapeutic regimens; indicating the importance to select a suitable treatment regimen in accordance with the mechanism of neuropathy associated with Sjögren's syndrome.

Adrenal Cortex Hormones↗
PubMed2003

[Brain ischemia--regenerative therapy using human neural stem cells].

The mortality of stroke is still the those of single organs. Even if patients survive the brain attack they often suffer from not only motor functional disability but also psychiatric problems such as post-stroke depression and decrease in spontaneity. The stoke is the number one cause of the bed-ridden state "Netakiri". Presently only anti-thrombotic and anti-oxidative stress therapies are available and the ischemic core destroyed immediately after the stroke could never be rescued. We have started to study the basic aspect of transplantation therapy of cerebral infarction using neural stem cells. Using a focal ischemic model of the gerbil by repeated occlusion of the unilateral carotid artery, we grafted human neural stem cells which were cultured and proliferated for a long period. Grafted animals showed significant and marked improvement in all three functions including motor, sensory and cognitive functions associated with a significant reduction of infarction volume. Synaptic contacts between neurons from grafted human neural stem cells and host neurons were confirmed by immuno-electron microscopy. This is a very encouraging report although it is necessary to elucidate the precise mechanism of the functional recovery or the effect of neural stem cell transplantation.

Animals↗
PubMed2002

Motor weakness and cerebellar ataxia in Sjögren syndrome--identification of antineuronal antibody: a case report.

We report here a combination of rare neurological manifestations of primary Sjögren syndrome (SS), such as motor-dominant motor weakness of peripheral origin, cerebellar ataxia and depression, in a Japanese female patient. An autoantibody in her serum and cerebrospinal fluid immunolabelled spinal motor neurons and cerebellar Purkinje cells. On Western blot, this antibody reacted with a protein of 34 kDa from the extract of spinal cord, dorsal root ganglion, or cerebellar cortex, which might correspond to motor weakness and cerebellar ataxia, respectively. The absence of its reactivity to the liver tissue indicates that this autoantibody targets an antigen represented exclusively in the neural tissues. Although it remains to be proved how autoantibodies, sometimes associated with SS, are involved in the development of clinical pictures, some of them are present in the cerebrospinal fluid and exhibit an exclusive affinity to neural tissues, which indicates its plausible link to neurological manifestations. Recognition of these antineuronal antibodies in SS will potentially provide a chance to treat these patients by removing or inactivating the antibody.

Animals↗
PubMed2002

Biochemical characterization of the core structure of alpha-synuclein filaments.

Intracellular filamentous aggregates comprised of alpha-synuclein such as Lewy bodies and glial cytoplasmic inclusions are the defining hallmarks of a subset of neurodegenerative diseases including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. We have analyzed biochemical and structural properties of alpha-synuclein filaments assembled in vitro or extracted from brains of patients with multiple system atrophy and found that both types of filaments are insoluble to detergents and partially resistant to proteinase K digestion. Immunoelectron microscopy and immunoblot analysis showed that both amino and carboxyl termini of alpha-synuclein in in vitro assembled filaments were degraded by proteinase K treatment, whereas the central portion of alpha-synuclein is resistant to proteinase K and retains filamentous structures. Protein sequencing and mass spectrometric analyses of the proteinase K-resistant, minimal fragment of 7 kDa revealed that amino acid residues 31-109 of alpha-synuclein constitute the core unit of the filaments. These observations suggest that the central half of the alpha-synuclein polypeptide, containing five tandem repeats as well as a part of the carboxyl-terminal acidic region, forms the core structure of alpha-synuclein filaments, which is coated by the amino- and carboxyl-terminal portions at the periphery.

Amino Acid Sequence↗
PubMed2002

A novel mutation in the GNE gene and a linkage disequilibrium in Japanese pedigrees.

Distal myopathy with rimmed vacuoles (DMRV) is an autosomal recessive muscular disorder characterized by weakness of the anterior compartment of the lower limbs with onset in early adulthood and sparing of the quadricep muscles. The UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE) gene was recently identified as the causative gene for hereditary inclusion body myopathy (HIBM). To investigate whether DMRV and HIBM are allelic diseases, we conducted mutational analysis of the GNE gene of six Japanese DMRV pedigrees and found that all the pedigrees share a homozygous mutation (V572L) associated with a strong linkage disequilibrium, suggesting a strong founder effect in Japanese DMRV pedigrees.

Carbohydrate Epimerases↗
PubMed2002

Electrophysiological evaluation of conduction in the most proximal motor root segment.

Root conduction time (RCT), defined as the time difference between M-wave latency by cervical magnetic stimulation (CMS) and the total peripheral motor conduction time calculated from the shortest F-wave latency, was investigated in patients with inflammatory demyelinating neuropathies (IDP) and amyotrophic lateral sclerosis (ALS). The minimal threshold for CMS also was studied. In the IDP patients, conduction in the proximal motor root segment was considered abnormal in 52% by the RCT and in 47% by the minimal threshold for CMS, whereas both were normal in 85% of the ALS patients. These findings suggest that the RCT and minimal threshold for CMS might be additional parameters for evaluating motor nerve conduction in IDP.

Action Potentials↗
PubMed2002

Heterogeneity of nigral and cortical Lewy bodies differentiated by amplified triple-labeling for alpha-synuclein, ubiquitin, and thiazin red.

Alpha-synuclein(alpha-S) and ubiquitin(Ub) are constituents of the Lewy bodies (LBs), composed of fibrillary structures. To clarify morphological heterogeneity of LBs, we looked for localization of these epitopes in relation to fibrillary structure possibly detectable by a fluorochrome, thiazin red (TR). On the sections of the substantia nigra (SN) and the cingulate gyrus (CG) obtained from Parkinson's disease brains, double amplification by CARD fluorescent immunohistochemistry with anti-alpha-S monoclonal (LB509) and anti-Ub polyclonal antibodies was performed, followed by staining with TR. These triple-labeled images were captured by a confocal laser microscope and subsequently stained with Campbell-Switzer method, a silver staining specific for LBs. Staining profiles of LBs were different between those in the SN and in the CG. Immunolabeling either with the anti-alpha-S or anti-Ub antibody was diffuse without halo structure in LBs of CG. In addition to this diffuse staining, a lot of LBs of SN exhibited a halo structure immunopositive for alpha-S and Ub, probably representing later stages of LB evolution. Irrespective of the presence of this halo structure, the TR signal was always concentrated in the center of LBs, as the silver-stained material was, suggesting that fibrillary components in the central portion of LBs undergo some conformational changes detectable by TR and the silver-staining. This technique reveals different epitopes in relation to LB evolution in vivo. Heterogeneity in staining profile of LBs, as clarified by this method, may represent evolutional changes of LBs, related to conformational states of their constituents.

Aged↗
PubMed2002

Ultrastructural and MRI study of the substantia nigra evolving exofocal post-ischemic neuronal death in the rat.

To clarify the morphological characteristics of exofocal post-ischemic neuronal death (EPND) in the substantia nigra (SN), we investigated the course of light- and electron-microscopic changes of the SN of rats subjected to occlusion of the left middle cerebral artery (MCA) for 1, 2, 4, 7 and 12 days. To assess cellular edema, sequential magnetic resonance (MR) mapping of the apparent diffusion coefficient (ADC) and the T2 value test was performed. Histological and electron-microscopic examination on day 1 showed dotted chromatin clumps in the nuclei of some neurons and mild swelling of the perivascular endfeet of astrocytes in the ipsilateral SN. On day 2, a few cells of the ipsilateral SN pars reticulata (SNr) revealed key morphological signs of apoptosis--apoptotic body-like condensation and segregation of the chromatin and DNA fragmentation-like nuclear remnants. On day 4, 38% of neurons became swollen (pale neurons) with cytoplasmic microvacuoles, which appeared to originate from rough endoplasmic reticulum (rER), mitochondria and Golgi apparatus. Twenty percent of neurons showed massive proliferation of the cisternae of the rER, some of which were fragmented or had lost their normal parallel arrangement. In addition, MR mapping revealed a transient ADC decrease with a T2 increase (signifying a phase of cellular edema), which coordinated with the phase of ultrastructural cellular swelling. Further, the total number of neurons started to decrease gradually, the perivascular endfeet of astrocytes were markedly swollen, and the neuropil became loose on day 4. On day 7, reactive astrocytes and dark neurons occurred most frequently. These results suggest that the EPND in the SN after occlusion of the MCA in adult rats is due to both apoptosis and necrosis, although necrosis seems to be the dominant mechanism of the EPND. However, the morphologic resemblances of EPND to delayed neuronal death suggest these processes have a common pathomechanism.

Animals↗
PubMed2001

Novel Cav2.1 splice variants isolated from Purkinje cells do not generate P-type Ca2+ current.

The alpha(1)2.1 (alpha(1A)) subunits of P-type and Q-type Ca(2+) channels are encoded by a single gene, Cacna1a. Although these channels differ in the inactivation kinetics and sensitivity to omega-agatoxin IVA, the mechanism underlying these differences remains to be clarified. Alternative splicings of the Cacna1a transcript have been postulated to contribute to the respective properties, however, the splice variants responsible for P-type Ca(2+) channels have not been identified. To explore P-type-specific splice variants, we aimed at cloning alpha(1)2.1 from isolated mouse Purkinje cells using single-cell reverse transcription-PCR, because in Purkinje cells P-type currents dominate over the whole currents (>95%) with Q-type currents undetected. As a result, two novel splice variants were cloned. Compared with the previously cloned mouse alpha(1)2.1, two novel variants had additional 48 amino acids at the amino termini, six single amino acid changes, and splicing variations at the exon 46/47 boundary, which produced different carboxyl termini. Furthermore, one variant had one RNA editing site. However, electrophysiological and pharmacological studies indicated that these variants did not generate P-type current in cultured cells. These results suggest that P-type-specific splice variants may exist but that post-translational processing or modification by uncharacterized interacting proteins is also required for generating the P-type current.

Alternative Splicing↗