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Biomedical subjects

I Kanazawa

Publications and source records attributed to I Kanazawa.

At least 73 records · Page 4Linked to original sources
PubMed2000

Cloning and expression study of the mouse tetrodotoxin-resistant voltage-gated sodium channel alpha subunit NaT/Scn11a.

We have cloned a tetrodotoxin-resistant (TTX-R) voltage-gated sodium channel alpha subunit from a mouse cDNA library and designated it as NaT. It encodes 1765 amino acid residues and is virtually identical to that of Scn11a, which has been reported recently, except for 40 nt and 14 aa substitutions. The amino acid identity of NaT/Scn11a with rat NaN/SNS2 is 88%. NaT/Scn11a was mapped to mouse chromosome 9F3-F4 by fluorescence in situ hybridization (FISH). While rat NaN/SNS2 has been reported to be expressed specifically in the peripheral sensory neurons, NaT/Scn11a is expressed not only in the peripheral sensory neurons but also in the spinal cord, uterus, testis, ovary, placenta, and small intestine. NaT is detectable in mouse embryos 15 days postcoitus (p.c.), around the phase of organogenesis and gonadal differentiation. These findings demonstrate a unique distribution of NaT/Scn11a and suggest some of its roles in the above-mentioned processes.

Amino Acid Sequence↗
PubMed2000

Identification of a novel human voltage-gated sodium channel alpha subunit gene, SCN12A.

We have cloned a cDNA encoding a novel human voltage-gated sodium channel alpha subunit gene, SCN12A, from human brain. Two alternative splicing variants for SCN12A have been identified. The longest open reading frame of SCN12A encodes 1791 amino acid residues. The deduced amino acid sequence of SCN12A shows 37-73% similarity with various other mammalian sodium channels. The presence of a serine residue (S360) in the SS2 segment of domain I suggests that SCN12A is resistant to tetrodotoxin (TTX), as in the cases of rat Scn10a (rPN3/SNS) and rat Scn11a (NaN/SNS2). SCN12A is expressed predominantly in olfactory bulb, hippocampus, cerebellar cortex, spinal cord, spleen, small intestine, and placenta. Although expression level could not be determined, SCN12A is also expressed in dorsal root ganglia (DRG). Both neurons and glial cells express SCN12A. SCN12A maps to human chromosome 3p23-p21.3. These results suggest that SCN12A is a tetrodotoxin-resistant (TTX-R) sodium channel expressed in the central nervous system and nonneural tissues.

Amino Acid Sequence↗
PubMed2000

Jugular foramen syndrome caused by varicella zoster virus infection in a patient with ipsilateral hypoplasia of the jugular foramen.

We report a patient with acute cranial polyneuropathy with unilateral involvement of the ninth, tenth, and eleventh cranial nerves. Although this patient lacked a typical cutaneous herpetic manifestation, elevated levels of IgM and IgG antibodies to varicella zoster virus (VZV) in both the serum and cerebrospinal fluid confirmed the clinical diagnosis of VZV infection and zoster sine herpete. Coexisting hypoplasia of the ipsilateral jugular foramen was detected using three-dimensional, surface-rendering displays reconstructed from the cranial helical CT scan. The patient recovered almost completely following treatment with an anti-inflammatory corticosteroid. Anatomical narrowing of the jugular foramen in this patient may have contributed to entrapment of the affected nerves at their passage through the foramen.

Accessory Nerve↗
PubMed2000

Cell cycle arrest enhances the in vitro cellular toxicity of the truncated Machado-Joseph disease gene product with an expanded polyglutamine stretch.

Machado-Joseph disease (MJD) is an inherited neurodegenerative disorder caused by the expansion of the polyglutamine stretch in the MJD gene-encoded protein, ataxin-3. Using a series of deletion constructs expressing ataxin-3 fragments with expanded polyglutamine stretches, we observed aggregate formation and cell death in cultured BHK-21 cells. The cytotoxic effect of N-terminal-truncated ataxin-3 with the expanded polyglutamine tract was enhanced under serum starvation culture, in which cells were arrested in the G(0)/G(1)phase. Coexpression of p21 (waf1/cip1/sdi1), a cyclin-Cdk inhibitor that induced cell cycle arrest in the G(1)phase, also increased the cell death susceptibility produced by the mutant ataxin-3 fragment in BHK-21 cells. The elevated susceptibility to cell death in the G(0)/G(1)phase was confirmed in nerve growth factor-treated, postmitotic neuronal PC12 cells compared with undifferentiated proliferating PC12 cells. These results strongly suggest that the cellular toxicity of truncated ataxin-3 with an expanded polyglutamine stretch is enhanced by cell cycle arrest in the G(0)/G(1)phase. Mutant ataxin-3 may confer a higher susceptibility to cell death on cells in the G(0)/G(1)phase.

Animals↗
PubMed2000

Secretory granules of pituitary adenomas: quantitative study of hormonal antigenicity.

Ultrastructurally, the antigenicity of major pituitary hormones in secretory granules was quantitatively investigated in five growth hormone (GH)-secreting adenomas, five prolactin (PRL)-secreting adenomas and eight clinically non-functioning (CN-F) adenomas. Sparsely granulated cells with a few or several small secretory granules (60-100 nm) exhibiting little or only weak antigenicity of various biochemically unrelated hormones were commonly observed in CN-F adenomas and occasionally in GH- and PRL-secreting adenomas. GH- or PRL-secreting adenomas consisted of many densely granulated cells with medium-sized (200-250 nm) or large (over 250 nm) secretory granules and a few or several sparsely granulated cells with small secretory granules. The densely granulated cells showed intense GH or PRL antigenicity and slight to moderate antigenicity for other hormones in large secretory granules and little or only weak antigenicity for various hormones including GH or PRL in small secretory granules. Their secretory granules larger than 160 nm or 140 nm significantly exhibited intense GH or PRL antigenicity (Fisher's exact test; P < 0.05 and < 0.01, respectively). Two CN-F adenomas showed sparsely and densely granulated cells as well as intermediate cells. The densely granulated cells closely resembled GH-secreting cells. The intermediate cells simultaneously included small and medium-sized or large secretory granules exhibiting little/slight and intense GH-antigenicity, respectively. This study indicates that sparsely granulated cells of different categories showing slight antigenicity for various hormones, antigenically share the same origin, and that their hormonality, single or multiple, may be selectively activated in the developmental course of secretory granules.

Adult↗
PubMed2000

Saccular cerebral aneurysms in young adults.

BACKGROUND: The formation and rupture of cerebral aneurysms has been controversial. In order to clarify their nature, this study investigates the size and location of ruptured and unruptured aneurysms in young adults and the results of surgery. METHODS: The subjects of this study are 35 patients with ruptured and two with unruptured aneurysms. They range in age from 20 to 39 years. The size and location of their aneurysms were determined by angiographic measure of their maximal inner diameters. Direct surgery was performed on 34 patients with ruptured aneurysms and on one with an unruptured aneurysm. RESULTS: Ruptured aneurysms in young adults increase in number and size as they grow older. In young adults showing no atherosclerosis or hypertension, ruptured aneurysms occurred in locations and with a frequency found in patients with hypertension. In young adults, aneurysms in the internal carotid artery larger than 3.5 mm (Fisher's exact test; p < 0.05) and the anterior communicating artery showed a tendency to rupture. The surgery produced excellent results in young adults with grade I to III by Hunt and Kosnik classification, but extremely poor results for those with grade IV resulting from vasospasm (Fisher's exact test; p < 0.05). CONCLUSION: It is possible that aneurysms found in young adults might in fact have been present from childhood and adolescence, increasing sufficiently in size to rupture in the forties and fifties. Accordingly, while aneurysm formation may be related to fragile arterial walls, aneurysm rupture may be the result of aging factors such as hypertension and atherosclerosis. Even in young adults, vasospasm had an impact on the outcome of surgery.

Adult↗
PubMed2000

Different cortical activity in reading of Kanji words, Kana words and Kana nonwords.

We report a positron emission tomography study on reading of Japanese Kanji (morphograms) words, Kana (phonograms) words and Kana nonwords using statistical parametric mapping. Activity was more pronounced in the lateral fusiform gyrus (Area 37) in Kanji, in contrast to the greater activation in the middle and inferior occipital gyri (Areas 18 and 19) and the deep perisylvian temporo-parietal area (Areas 40/22 and 22/21) in Kana, suggesting that Kanji and Kana are processed differently.

Adolescent↗
PubMed2000

The human hand motor area is transiently suppressed by an unexpected auditory stimulus.

OBJECTIVE: To study the effect of a loud auditory stimulus on the excitability of the human motor cortex. METHODS: Ten normal volunteers participated in this study. The size of responses to transcranial magnetic or electrical cortical stimulation (TMS or TES) given at different times (ISIs) after a loud sound were compared with those to TMS or TES alone (control response). Different intensities and durations of sound were used at several intertrial intervals (ITIs). In addition, we examined how the presence of a preceding click modulated the effect of a loud sound (prepulse inhibition). The incidence of startle response evoked by various stimuli was also studied. RESULTS: A loud auditory stimulus suppressed EMG responses to TMS when it preceded the magnetic stimulus by 30-60 ms, whereas it did not affect responses to TES. This suggests that the suppression occurred at a cortical level. Significant suppression was evoked only when the sound was louder than 80 dB and longer than 50 ms in duration. Such stimuli frequently elicited a startle response when given alone. The effect was not evoked if the ITI was 5 s, but was evoked when it was longer than 20 s. A preceding click reduced the suppression elicited by loud sounds. CONCLUSIONS: Auditory stimuli that produced the greatest effect on responses to TMS had the same characteristics as those which yielded the most consistent auditory startle. We suggest that modulation of cortical excitability occurs in parallel with the auditory startle and both may arise from the same region of the brain-stem.

Acoustic Stimulation↗
PubMed2000

Expanded polyglutamine stretches interact with TAFII130, interfering with CREB-dependent transcription.

At least eight inherited neurodegenerative diseases are caused by expanded CAG repeats encoding polyglutamine (polyQ) stretches. Although cytotoxicities of expanded polyQ stretches are implicated, the molecular mechanisms of neurodegeneration remain unclear. We found that expanded polyQ stretches preferentially bind to TAFII130, a coactivator involved in cAMP-responsive element binding protein (CREB)-dependent transcriptional activation, and strongly suppress CREB-dependent transcriptional activation. The suppression of CREB-dependent transcription and the cell death induced by polyQ stretches were restored by the co-expression of TAFII130. Our results indicate that interference of transcription by the binding of TAFII130 with expanded polyQ stretches is involved in the pathogenetic mechanisms underlying neurodegeneration.

Aged↗
PubMed2000

Guillain-Barré syndrome with antibody to a ganglioside, N-acetylgalactosaminyl GD1a.

A retrospective case study of 33 Guillain-Barré syndrome (GBS) patients with the antibody to the ganglioside N-acetylgalactosaminyl GD1a (GalNAc-GD1a) was made to investigate the clinical features of GBS with this antibody. Patients were classified into three groups: (i) 25 with IgG antibody (group G, titre >/= 1 : 40); (ii) 16 with high-titre IgG antibody (group G-high, titre >/=1:320; selected from group G patients), and (iii) eight with IgM antibody but without elevation of IgG (group M, normal range <1:40 for both IgM and IgG). The control group consisted of 72 GBS patients without anti-GalNAc-GD1a antibody. Compared with the control group, the G-high and G group patients were characterized as having had antecedent gastrointestinal infection (87% and 72% versus 31%, both P < 0.001), uncommon cranial nerve involvement (19% and 36% versus 54%, P = 0.02 and 0.2, respectively), distal-dominant weakness (94% and 68% versus 36%, P < 0.001 and P = 0.01, respectively) and no sensory signs (81% and 60% versus 25%, P < 0.001 and P = 0.003, respectively). Electrophysiological findings indicative of axonal dysfunction were significantly more common in the G-high and G group patients (63% and 52% versus 14%, both P < 0.001). The pure motor variant that showed neither sensory signs nor abnormalities in sensory conduction studies was also more frequent in these groups (44% and 32% versus 9%, both P < 0.001). IgG anti-GalNAc-GD1a antibody may be a marker of the pure motor and the axonal variants of GBS, and therefore it, as well as anti-GM1 antibody, must be investigated in these forms in order to diagnose and understand the variants. By contrast, mild weakness, frequent facial palsy (75%) and a high incidence of IgM anti-GM2 antibody reactivity (88%) were characteristic of group M, indicating that the GBS in that group resulted from a different immune mechanism from that in the G group.

Adult↗
PubMed2000

[Treatment of advanced Parkinson's disease].

After the advent of levodopa, treatment of Parkinson's disease has changed and the activity of daily life of patients has been remarkably improved; whereas, many patients experience various problems such as wearing-off, dyskinesia, dystonia, neuropsychiatric problems, and dysautonomia. Especially, wearing-off and dyskinesia emerge with the change of absorptional pattern of levodopa and could be solved by regulating the timing and the dose of it. Recently, some new drugs for Parkinson's disease have been available and we physician have a wide choice of them. It is important to make a careful choice of and manipulate of doses of drugs after understanding daily life of each patient enough.

Antiparkinson Agents↗
PubMed2000

[A case of unilateral recurrent calf myalgia with muscle edema due to venous congestion].

We report a 38-year-old man who had three episodes of pain and swelling in the right calf from the age of 27 years. On each episode, pain worsened gradually, lasted for a few months and subsided spontaneously. Venography performed at the first episode was reported to be unremarkable. At the third episode, physical examinations showed tender and hard muscles in the right calf without findings of knee arthritis. The right calf pain became stronger when standing than when lying and on the ankle dorsiflexion. Laboratory examinations showed leukocytosis, a slightly elevated level of CRP, and normal CK levels. MRI showed diffuse high intensities in the right soleus and the lateral head of right gastrocnemius on T2-weighted images, where CT showed slightly low densities. To rule out focal myositis, the right soleus was biopsied. The muscle specimen showed perimysial and endomysial edema, dilatation of venules and capillaries, and focal mononuclear cell infiltration in the venule wall. Intermyofibrillar networks were well preserved. There were no necrotic or regenerating fibers, nor sarcolemmal expression of HLA-ABC. On electron microscopy, the processes of fibroblasts in the endomysium were swollen. This case illustrated muscle edema caused by local venous congestion possibly due to venulitis of unknown cause.

Adult↗
PubMed1999

AP-2beta represses D(1A) dopamine receptor gene transcription in neuro2a cells.

Expression of the D(1A) dopamine receptor in brain is restricted to specific neuronal populations. To investigate the mechanism of this selective expression, we localized a silencer upstream of the human D(1A) gene and identified its binding transcription factor in the D(1A)-negative neural cell line Neuro2a. Using deletion CAT analysis, we narrowed this silencer to the region between nucleotides -561 and -532 relative to the CAP site. This 30-bp region, designated D1AS1, contains a sequence homologous to the AP-2 binding site and binds to a factor that also interacts with the AP-2 consensus sequence. In gel supershift assays, this factor is recognized by anti-AP-2beta antibody. Co-transfection of Neuro2a cells with an AP-2beta expression vector repressed the basal CAT activity of D(1A) promoter-reporter plasmids in a D1AS1-dependent manner. RT-PCR analysis indicated that, among AP-2 family members, Neuro2a cells express only AP-2beta. Furthermore, co-transfection of these cells with decoy oligonucleotides corresponding to the D1AS1 sequence de-repressed the D(1A) gene promoter. Unlike in Neuro2a cells, AP-2beta could not repress the D(1A) promoter in the D(1A)-positive neural cell line, NS20Y. In addition, the expression of AP-2beta in different brain regions does not inversely correlate with that of D(1A) dopamine receptor. These observations taken together indicate that AP-2beta is a repressive transcription factor that acts on the D1AS1 silencer of the D(1A) dopamine receptor gene via some cell-specific mechanism(s) in Neuro2a.

Animals↗
PubMed1999

Serum antibody against a peripheral nerve myelin ganglioside, LM1, in Guillain-Barré syndrome.

Serum IgG antibody against LM1, the predominant ganglioside in the human peripheral nerve myelin, was found in 7 out of 140 patients with Guillain-Barré syndrome (GBS) in the acute phase, 1 out of 33 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), and 2 out of 47 patients with Miller Fisher syndrome (MFS). Anti-LM1 IgM antibody was detected only in 2 patients, each with GBS and MFS. The clinical and electrophysiological features of the seven GBS patients with anti-LM1 IgG antibody in the serum were investigated. Six patients recovered to grade 1 within one month of the onset of neuropathy. Electrophysiological studies revealed demyelination in five patients, of which one had axonal damage in addition, whereas sufficient evidence of demyelination or axonal degeneration was not observed in the remaining two. Five had a respiratory tract infection before the onset of neuropathy, and also had serum anti-GQ1b IgG antibody. IgG antibody against LM1 might be involved in the pathogenetic mechanisms of GBS, as a possible demyelinating factor. Presence of both anti-GQ1b and anti-LM1 antibodies may be associated with some infectious agent(s) affecting the respiratory tract.

Antibodies, Bacterial↗
PubMed1999

Presenilin 1 suppresses the function of c-Jun homodimers via interaction with QM/Jif-1.

Presenilin 1 (PS1) is the causative gene for an autosomal dominant familial Alzheimer's disease (AD) mapped to chromosome 14. Here we show that QM/Jun-interacting factor (Jif)-1, a negative regulator of c-Jun, is a candidate to mediate the function of PS1 in the cell. We screened for proteins that bind to PS1 from a human embryonic brain cDNA library using the two-hybrid method and isolated one clone encoding the QM/Jif-1 gene. The binding of QM/Jif-1 to full-length PS1 was confirmed in vitro by pull-down assay, and in vivo by immunoprecipitation assays with human samples, including AD brains. Immunoelectronmicroscopic analysis showed that QM/Jif-1 and PS1 are colocalized at the endoplasmic reticulum, and the nuclear matrix in human brain neurons. Chloramphenicol acetyltransferase assays in F9 cells showed that PS1 suppresses transactivation by c-Jun/c-Jun but not by c-Jun/c-Fos heterodimers, consistent with the reported function of QM/Jif-1. By monitoring fluorescent recombinant protein and by gel mobility shift assays, PS1 was shown to accelerate the translocation of QM from the cytoplasm to the nucleus and to thereby suppress the binding of c-Jun homodimer to 12-O-tetradecanoylphorbol-13- acetate (TPA)-responsive element (TRE). PS1 suppressed c-jun-associated apoptosis by retinoic acid in F9 embryonic carcinoma cells, whereas this suppression of apoptosis is attenuated by mutation in PS1. Collectively, the novel function of PS1 via QM/Jif-1 influences c-jun-mediated transcription and apoptosis.

Adult↗
PubMed1999

Degeneration of rabbit sensory neurons induced by passive transfer of anti-GD1b antiserum.

Systemic infusion of high-titer anti-GD1b antiserum to two rabbits pre-inoculated with keyhole limpet hemocyanin and Freund's complete adjuvant was performed. The two rabbits had low-titer anti-GD1b antibody in sera. Although no apparent clinical signs were observed, pathological examinations showed vacuolar degeneration with macrophage infiltration in a few axons in the dorsal columns of the spinal cords from the two rabbits. No such pathological changes were observed in the other two pre-inoculated rabbits infused with normal rabbit sera. Anti-GD1b antibody therefore may cause degeneration in rabbit sensory neurons with central axons extending to the dorsal column.

Animals↗