Search PubMed⌕ Search

Biomedical subjects

I Kanazawa

Publications and source records attributed to I Kanazawa.

At least 37 records · Page 2Linked to original sources
PubMed2001

Age-dependent and tissue-specific CAG repeat instability occurs in mouse knock-in for a mutant Huntington's disease gene.

Huntington's disease (HD) is a neurodegenerative disorder characterized by the expansion of CAG repeats in exon 1 of the HD gene. To clarify the instability of expanded CAG repeats in HD patients, an HD model mouse has been generated by gene replacement with human exon 1 of the HD gene with expansion to 77 CAG repeats. Chimeric proteins composed of human mutated exon 1 and mouse huntingtin are expressed ubiquitously in brain and peripheral tissues. One or two CAG repeat expansion was found in litters from paternal transmission, whereas contraction of CAG repeat in litters was observed through maternal transmission. Elderly mice show greater CAG repeat instability than younger mice, and a unique case was observed of an expanded 97 CAG repeat mouse. Somatic CAG repeat instability is particularly pronounced in the liver, kidney, stomach, and brain but not in the cerebellum of 100-week-old mice. The same results of expanded CAG repeat instability as observed in this HD model mouse were confirmed in the human brain of HD patients. Glial fibrillary acidic protein (GFAP)-positive cells have been found to be increased in the substantia nigra (SN), globus pallidus (GP), and striatum (St) in the brains of 40-week-old affected mice, although without neuronal cell death. The CAG repeat instability and increase in GFAP-positive cells in this mouse model appear to mirror the abnormalities in HD patients. The HD model mouse may therefore have advantages for investigations of molecular mechanisms underlying instability of CAG repeats.

Age Factors↗
PubMed2001

SCA17, a novel autosomal dominant cerebellar ataxia caused by an expanded polyglutamine in TATA-binding protein.

Genetic etiologies of at least 20% of autosomal dominant cerebellar ataxias (ADCAs) have yet to be clarified. We identified a novel spinocerebellar ataxia (SCA) form in four Japanese pedigrees which is caused by an abnormal CAG expansion in the TATA-binding protein (TBP) gene, a general transcription initiation factor. Consequently, it has been added to the group of polyglutamine diseases. This abnormal expansion of glutamine tracts in TBP bears 47--55 repeats, whereas the normal repeat number ranges from 29 to 42. Immunocytochemical examination of a postmortem brain which carried 48 CAG repeats detected neuronal intranuclear inclusion bodies that stained with anti-ubiquitin antibody, anti-TBP antibody and with the 1C2 antibody that recognizes specifically expanded pathological polyglutamine tracts. We therefore propose that this new disease be called SCA17 (TBP disease).

Adult↗
PubMed2001

Two consecutive zinc fingers in Sp1 and in MAZ are essential for interactions with cis-elements.

The zinc finger proteins Sp1 and Myc-associated zinc finger protein (MAZ) are transcription factors that control the expression of various genes. Regulation of transcription by these factors is based on interactions between GC-rich DNA-binding sites (GGGCGG for Sp1 and GGGAGGG for MAZ) and the carboxyl-terminal zinc finger motifs of the two proteins. Sp1 and MAZ have three and six zinc fingers, respectively, and the details of their interactions with cis-elements remain to be clarified. We demonstrate here that Sp1 and MAZ interact with the same GC-rich DNA-binding sites, apparently sharing DNA-binding sites with each other. We found that the DNA binding activities of Sp1 and MAZ depended mainly on consecutive zinc fingers, namely the second and third zinc fingers in Sp1 and the third and fourth zinc fingers in MAZ. Furthermore, the interactions of the zinc finger proteins with the same cis-elements appear to play a critical role in the regulation of gene expression. It seems plausible that two consecutive zinc finger motifs in a zinc finger protein might be essential for interaction of the protein with DNA.

3T3 Cells↗
PubMed2001

Variability in immunohistochemistries of IgM M-proteins binding to sulfated glucuronyl paragloboside.

Serum IgMs from 4 of 12 patients with polyneuropathy and IgM M-proteins that bind to sulfated glucuronyl paragloboside (SGPG) strongly immunostained the human peripheral nerve myelin (group A), whereas those from the other eight patients strongly immunostained the cytoplasm of the Schwann cells surrounding the myelin sheath with only weak staining of the myelin (group B). Strong immunostaining of peripheral myelin by IgMs from group A patients may be due to the strong cross-reactivities against P0 and peripheral myelin protein-22 (PMP-22), which are localized in compact myelin. Only three patients (all in group B) showed some response to the immunotherapies. Weak reactivities to P0 and and PMP-22 might indicate the possibility of improvement after the immunotherapies.

Aged↗
PubMed2001

Guillain-Barré syndrome associated with IgG monospecific to ganglioside GD1b.

The authors examined serum antiglycolipid antibodies in 445 patients with Guillain-Barré syndrome (GBS). Among them, nine had anti-GD1b IgG antibodies with no reactivity to other glycolipids tested. All those patients had sensory disturbance, and none had the primary axonal form. Anti-GD1b IgG antibodies may bind to primary sensory neurons and paranodal myelin, where GD1b is localized, and be involved in the pathogenesis of sensory disturbance and demyelination. However, more study is needed to substantiate the roles of anti-GD1b IgG antibodies.

Adult↗
PubMed2001

Independent repression of a GC-rich housekeeping gene by Sp1 and MAZ involves the same cis-elements.

The transcription factors Sp1 and MAZ (Myc-associated zinc finger protein) contain several zinc finger motifs, and each functions as both a positive and a negative regulator of gene expression. In this study, we characterized the extremely GC-rich promoter of the human gene for MAZ, which is known as a housekeeping gene. Unique symmetrical motifs in the promoter region (nucleotides -383 to -334) were essential for the expression of the gene for MAZ, whereas an upstream silencer element (nucleotides -784 to -612) was found to act in a position-dependent but orientation-independent manner. Sp1 and MAZ bound to the same cis-elements in the GC-rich promoter, apparently sharing DNA-binding sites. The relative extent of binding of Sp1 and MAZ to these cis-elements corresponded to the extent of negative regulation of the expression of the gene for MAZ in various lines of cells. Furthermore, novel repressive domains in both Sp1 (amino acids 622-788) and MAZ (amino acids 127-292) were identified. Suppression by Sp1 and suppression by MAZ were independent phenomena; histone deacetylases were involved in the autorepression by MAZ itself, whereas DNA methyltransferase 1 was associated with suppression by Sp1. Our results indicate that both deacetylation and methylation might be involved in the regulation of expression of a single gene via the actions of different zinc finger proteins that bind to the same cis-elements.

Animals↗
PubMed2001

Interhemispheric facilitation of the hand motor area in humans.

1. We investigated interhemispheric interactions between the human hand motor areas using transcranial cortical magnetic and electrical stimulation. 2. A magnetic test stimulus was applied over the motor cortex contralateral to the recorded muscle (test motor cortex), and an electrical or magnetic conditioning stimulus was applied over the ipsilateral hemisphere (conditioning motor cortex). We investigated the effects of the conditioning stimulus on responses to the test stimulus. 3. Two effects were elicited at different interstimulus intervals (ISIs): early facilitation (ISI = 4-5 ms) and late inhibition (ISI > or = 11 ms). 4. The early facilitation was evoked by a magnetic or anodal electrical conditioning stimulus over the motor point in the conditioning hemisphere, which suggests that the conditioning stimulus for early facilitation directly activates corticospinal neurones. 5. The ISIs for early facilitation taken together with the time required for activation of corticospinal neurones by I3-waves in the test hemisphere are compatible with the interhemispheric conduction time through the corpus callosum. Early facilitation was observed in responses to I3-waves, but not in responses to D-waves nor to I1-waves. Based on these results, we conclude that early facilitation is mediated through the corpus callosum. 6. If the magnetic conditioning stimulus induced posteriorly directed currents, or if an anodal electrical conditioning stimulus was applied over a point 2 cm anterior to the motor point, then we observed late inhibition with no early facilitation. 7. Late inhibition was evoked in responses to both I1- and I3-waves, but was not evoked in responses to D-waves. The stronger the conditioning stimulus was, the greater was the amount of inhibition. These results are compatible with surround inhibition at the motor cortex.

Conditioning, Psychological↗
PubMed2001

Hemispheric lateralization in the cortical motor preparation for human vocalization.

To investigate the cortical information processing during the preparation of vocalization, we performed transcranial magnetic stimulation (TMS) over the cortex while the subjects prepared to produce voice in response to a visual cue. The control reaction time (RT) of vocalization without TMS was 250-350 msec. TMS prolonged RT when it was delivered up to 150-200 msec before the expected onset of voice (EOV). The largest delay of RT was induced bilaterally over points 6 cm to the left and right of the vertex (the left and right motor areas), resulting in 10-20% prolongation of RT. During the early phase of prevocalization period (50-100 msec before EOV), the delay induced over the left motor area was slightly larger than that induced over the right motor area, whereas, during the late phase (0-50 msec before EOV), it was significantly larger over the right motor area. Bilateral and simultaneous TMS of the left and right motor areas induced delays not significantly different from that induced by unilateral TMS during the early phase, but induced a large delay well in excess of the latter during the late phase. Thus, during the cortical preparation for human vocalization, alternation of hemispheric lateralization takes place between the bilateral motor cortices near the facial motor representations, with mild left hemispheric predominance at the early phase switching over to robust right hemispheric predominance during the late phase. Our results also suggested involvement of the motor representation of respiratory muscles and also of supplementary motor cortex.

Adult↗
PubMed2001

Guillain-Barré syndrome with IgM antibody to the ganglioside GalNAc-GD1a.

We analyzed the characteristics of 29 Guillain-Barré syndrome (GBS) patients with IgM anti-GalNAc-GD1a antibodies. Fourteen of them had had an antecedent cytomegalovirus infection (CMV group) and 12 gastrointestinal infection (G-I group). Most of the G-I group patients (nine of 12) were subsequent to Campylobacter jejuni infection. Electrophysiological results in both groups patients predominantly indicated demyelinating neuropathy. The CMV group patients were characterized by slow progression and frequent facial and sensory deficits. IgM antibodies in their sera recognized an epitope shared by GalNAc-GD1a and GM2. The G-I group patients frequently showed motor type of GBS with cranial nerves spared. IgM antibodies specific to GalNAc-GD1a were present in their sera.

Adult↗
PubMed2001

Characterization and promoter analysis of the mouse gene for transcription factor Sp4.

Transcription factor Sp4 is a member of the Sp1 family. It functions differently from other members of this family, such as Sp1 and Sp3, and the gene for Sp4 is transcribed in a tissue-specific manner. Recent studies in mice suggest that Sp4 might play an important role in growth, viability, and male fertility. We report here the isolation and characterization of the gene for Sp4 from a mouse genomic library. The mouse gene for Sp4 was about 80 kb in length and it consisted of six exons and five introns. The promoter was found in a CpG island and had a high G+C content. The proximal promoter contained multiple putative binding sites for the transcription factors Sp1 and MAZ but lacked a consensus TATA box. Multiple sites for the initiation of transcription were mapped in a GC-rich region from 286 bp to 211 bp upstream of the ATG triplet at the site of initiation of translation, and all of the sites were either C or G. Transfection experiments and deletion analysis allowed us to localize the promoter to a region that was no more than 93 bp upstream from the first site of initiation of transcription. We also found that ectopic expression of Sp1 and of MAZ, but not of Sp3, suppressed expression of the Sp4 promoter in a dose-dependent manner.

Amino Acid Sequence↗
PubMed2001

Diphenylpyraline-responsive parkinsonism in cerebrotendinous xanthomatosis: long-term follow up of three patients.

A long-term follow-up study was made of three patients with cerebrotendinous xanthomatosis (CTX) associated with parkinsonism, two of whom were siblings. Besides typical CTX symptoms, all three patients showed severe parkinsonism. This observation has been rarely reported in CTX. The fact that the two siblings showed parkinsonism strongly suggests the genetic propensity to parkinsonism in these CTX patients. Positron emission tomography studies of the two patients revealed presynaptic dysfunction of the nigro-striatal dopaminergic system. Treatment with the reductase inhibitor hydroxymethyl glutaryl coenzyme successfully corrected the serum cholestanol level in the early stage of the disease, which, however, did not arrest the progression of clinical symptoms, particularly their parkinsonism. Clinically, levodopa had a little effect on parkinsonism, whereas an antihistamine drug, diphenylpyraline hydrochloride (DPP) had excellent effects on all three patients throughout the long-term follow up. The mechanism of the action of DPP on parkinsonism is unclear, however, the drug seems to be a therapeutic choice for treating parkinsonism in CTX.

Adult↗
PubMed2001

The genomic structure and expression of MJD, the Machado-Joseph disease gene.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder that is clinically characterized by cerebellar ataxia and various associated symptoms. The disease is caused by an unstable expansion of the CAG repeat in the MJD gene. This gene is mapped to chromosome 14q32.1. To determine its genomic structure, we constructed a contig composed of six cosmid clones and eight bacterial artificial chromosome (BAC) clones. It spans approximately 300kb and includes MJD. We also determined the complete sequence (175,330bp) of B445M7, a human BAC clone that contains MJD. The MJD gene was found to span 48,240bp and to contain 11 exons. Northern blot analysis showed that MJD mRNA is ubiquitously expressed in human tissues, and in at least four different sizes; namely, 1.4, 1.8, 4.5, and 7.5kb. These different mRNA species probably result from differential splicing and polyadenylation, as shown by sequences of the 21 independent cDNA clones isolated after the screening of four human cDNA libraries prepared from whole brain, caudate, retina, and testis. The sequences of these latter clones relative to the MJD gene in B445M7 indicate that there are three alternative splicing sites and eight polyadenylation signals in MJD that are used to generate the differently sized transcripts.

Alternative Splicing↗
PubMed2001

Recurrence of convexity meningiomas: tumor cells in the arachnoid membrane.

BACKGROUND: It remains open to debate why totally removed benign meningiomas recur. Two recurrent cases forced us to reconsider something corresponding to their recurrence that we had overlooked during Simpson grade I surgery. METHODS: This study is based on 24 recent and 9 earlier cases in which benign convexity meningiomas were totally removed by Simpson's grade I surgery. Tough or thick arachnoid membranes continuing to normal arachnoid membranes and contiguous to meningiomas but different from dura mater were encountered in 11 recent and at least 2 earlier cases. Such thick arachnoid membranes were left in place or only partially resected in two earlier cases but extensively resected in all recent cases. RESULTS: Light microscopy showed clusters of meningioma cells not in the removed dura mater but in the thick arachnoid membranes of an earlier case and 10 out of the 11 recent cases. Six and twelve years after initial surgery, recurrence of the 2 earlier cases was confirmed at subsequent surgery or diagnosed by neuro-imaging. By contrast, neuro-imaging from 30 to 132 months after initial surgery showed no recurrence in the 10 recent cases. A follow-up study over 5 years showed a significant difference in recurrence between Simpson's grade I surgery with and without extensive removal of surrounding thick arachnoid membranes (Fisher's exact test: p < 0.05). CONCLUSION: This study emphasizes the possibility that thick arachnoid membranes contiguous to meningiomas and continuous to normal arachnoid membranes, involving clusters of tumor cells, may relate to meningioma recurrence.

Adult↗
PubMed2001

Zonisamide has beneficial effects on Parkinson's disease patients.

Zonisamide (ZNS) is a generally well tolerated anticonvulsant that has beneficial effects on Parkinson's disease (PD). ZNS (300 mg/day) given to a patient with PD who incidentally had convulsive attacks, ameliorated the attacks and, surprisingly, his parkinsonian symptoms. We, therefore, carried out an open trial of ZNS on nine patients with PD. Patients were given 50-200 mg/day ZNS in addition to their anti-PD drugs. Seven clearly showed lessening of symptoms, especially wearing-off. We speculate that long lasting activation of dopamine synthesis by ZNS ameliorates parkinsonian symptoms, in particular wearing-off.

Aged↗
PubMed2001

Cortical activity associated with vocalization and reading proper.

To determine whether motor and premotor areas are involved in silent reading, we report a positron emission tomography study on reading aloud and covert reading. The anterior insula, primary sensorimotor cortex and supplementary motor area were activated separately in reading aloud compared with covert reading, but they were not activated in covert reading compared with fixation control, nor in a conjunction involving reading aloud and covert reading, suggesting the role of articulation or vocalization.

Brain Mapping↗
PubMed2001

Cortical activation in reading assessed by region of interest-based analysis and statistical parametric mapping.

Reanalysis of our positron emission tomography study on the reading of Japanese Kanji (morphograms) and Kana (phonograms) with Statistical Parametric Mapping (SPM) Version 96 (Cogn. Brain Res. 9 (2000) 111) were described in comparison with our previous region of interest (ROI)-based analysis. Some areas were activated in one analysis but not in the other, which was due to the methodological differences. Furthermore, we conducted cognitive subtraction analysis between Kanji and Kana and between Kana words and nonwords and confirmed that Kana words activated the lateral occipital gyri more extensively than Kanji words.

Adolescent↗
PubMed2001

A single motor unit recording technique for studying the differential activation of corticospinal volleys by transcranial magnetic stimulation.

The purpose of this method is to establish a single motor unit recording technique to study the differential activation of corticospinal volleys by various types of transcranial magnetic stimulation (TMS). TMS is performed with various coil orientations over the hand or leg motor areas and surface EMG, and single motor unit recordings are made either from the studied hand or leg muscle. Transcranial electrical stimulation (TES) is also performed over the motor cortex as well as at the foramen magnum level to determine the latency of D waves. The intensity of stimulation is set just above the motor threshold for each type of stimulation. This method makes it possible to activate some I volleys (especially I1 and I3 waves) preferentially, if not selectively, from the hand and leg motor areas. The obtained results accord well with recent epidural recording studies, which lends support to the validity of this method.

Differential Threshold↗