Biomedical subjects
I Inoue
Publications and source records attributed to I Inoue.
Lipophilic HMG-CoA reductase inhibitor has an anti-inflammatory effect: reduction of MRNA levels for interleukin-1beta, interleukin-6, cyclooxygenase-2, and p22phox by regulation of peroxisome proliferator-activated receptor alpha (PPARalpha) in primary endothelial cells.
We examined the effects of four 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (pravastatin, simvastatin, fluvastatin, and cerivastatin) on the production and expression of inflammatory cytokines and on enzyme expression involving prostaglandin and superoxide production in cultured human umbilical vein endothelial cells (HUVEC). All HMG-CoA reductase inhibitors significantly reduced interleukin-1beta and -6 mRNA expression and their protein levels in the culture medium, and also inhibited cyclooxygenase-2 mRNA expression and their protein levels. And these drugs induced peroxisome proliferator-activated receptor alpha (PPARalpha) and PPARgamma mRNA expression and their protein levels in HUVEC and hepatocyte. Moreover, the mRNA levels of p22phox, a 22-kD subunit and the protein levels of p47phox, a 47-kD subunit of nicotine adenine dinucleotide phosphate (NADPH) oxidase, was decreased by treatment with either simvastatin, fluvastatin or cerivastatin, and this effect was reversed by mevalonate, geranylgeraniol, farnesol, and cholesterol. The changes induced by HMG-CoA reductase inhibitors might be due to regulation of cellular cholesterol content level, cellular cholesterol metabolic pathway, and cellular PPARalpha activity, which was related with inflammation. This unique anti-inflammatory effect in addition to its hypolipidemic action, may be beneficial in preventing the vascular complications that are induced by hyperlipidemia.
Missense variations of the gene responsible for Wolfram syndrome (WFS1/wolframin) in Japanese: possible contribution of the Arg456His mutation to type 1 diabetes as a nonautoimmune genetic basis.
Recently, a novel gene for a putative transmembrane protein (WFS1/wolframin) was found to be mutated in patients with Wolfram syndrome or DI-DM-OA-D (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness) syndrome. It is suggested that the WFS1 protein is important in the survival of islet beta-cells. We studied the WFS1 gene in a Japanese population to assess its possible role in common type 1 diabetes. Mutation screening revealed four missense mutations; R456H, G576S, H611R, and I720V. By genetic association studies of 185 type 1 diabetes patients and 380 control subjects, we found that R456H was significantly increased in the type 1 diabetes group compared to the control group (P = 0.0005); H611R and I720V were also significantly increased with weaker significance. Furthermore, in patients with the R456H mutation, type 1 diabetes-resistant HLA-DRB1 alleles (DRB1*0406, 1501, and 1502) were significantly increased compared to mutation-negative patients while susceptible DRB1*0901 was significantly decreased. Frequencies of autoimmunity characteristics (ICA or GAD-Ab positiveness and combination of autoimmune thyroid disease) were decreased in the R456H-positive patients compared to the R456H-negative patients. These data suggest that the WFS1 gene may have a role in the development of common type 1 diabetes as a nonautoimmune genetic basis.
Cloning of cDNA and the gene encoding human hepatocyte nuclear factor (HNF)-3 beta and mutation screening in Japanese subjects with maturity-onset diabetes of the young.
AIMS/HYPOTHESIS: Molecular defects of the genes for transcription factors, hepatocyte nuclear factor (HNF)-4 alpha, HNF-1 alpha, HNF-1 beta and insulin promoter factor-1 cause maturity-onset diabetes of the young (MODY1, 3, 5, and 4, respectively). This suggests the HNF-related transcription cascade is important in insulin secretion which is induced by glucose. These genes and the gene encoding glycolytic enzyme glucokinase (MODY2) are, however, responsible for only 15-20% of cases of MODY in the Japanese. Searching for a novel form of MODY in this population, we cloned a new candidate gene encoding human HNF-3 beta, a winged helix transcription factor, which also belongs to the same HNF-transcription cascade. METHODS: The cDNA clone for human HNF-3 beta was isolated from a liver cDNA library. The gene was also cloned from a genomic library and its organization and chromosomal localization were determined. We screened 68 Japanese subjects with MODY/early-onset diabetes for mutations in this gene. RESULTS: Human HNF-3 beta is composed of 457 amino acids. The human gene, which was mapped to the segment 30 cR from SHGC-37039 on chromosome 20p by radiation hybrid mapping, spans approximately 4.5 kb and consists of three exons. Direct sequencing of the exons and flanking regions identified one missense mutation A328 V and seven polymorphisms, although the functional significance of the mutation in the pathogenesis of diabetes is not known. CONCLUSION/INTERPRETATION: The characterization of the structure of the HNF-3 beta gene and its mapping in the framework of markers will be helpful in genetic studies of the various forms of diabetes mellitus.
Lack of association of the Ala45Thr variant in the BETA2/NEUROD1 with type 1 diabetes in Japanese.
To evaluate the role of the Ala45Thr variant of BETA2/NEUROD1 in the development of type 1 or type 2 diabetes, we studied a Japanese population consisting of 383 control subjects, 234 type 1 diabetes patients and 160 type 2 diabetes patients. Both genotypewise and allelewise, there was no significant association of the variant with type 1 diabetes or type 2 diabetes in Japanese. Also, there were no significant differences in clinical characteristics with and without the variant. Our present results do not support a recent report which described an association of the Ala45Thr variant with type 1 diabetes in Japanese.
Activation of locomotor and grasping spine muscle fibres in chaetognaths: a curious paradox.
Chaetognath muscle fibres resemble vertebrate muscle fibres in having an abundant sarcoplasmic reticulum (SR) and analogues of the transverse (T) tubular system. but contraction is regulated differently. In intact chaetognaths electrically-evoked contractions of the striated locomotor muscles were largely or totally blocked by d-tubocurarine, by surgical removal of the ventral ganglion and by Co2 +. Contractions of single cells enzymatically dissociated from locomotor muscles were likewise blocked by Co2+, they twitched once only after calciseptine, showed neither contractures nor elevated intracellular Ca2+ with caffeine, and ryanodine did not block contractions. Whole cell voltage-clamped locomotor muscle cells displayed a typical inward rectified Ca2 + current that was sensitive to the Ca2+ channel blockers nifedipine and calciseptine and showed voltage-dependent activation with a threshold at approximately-25 mV and a peak inward current at approximately + 10 mV. In contrast, whole cell voltage-clamped cells from the muscles operating the grasping spines of the head showed an initial very rapid and rapidly-inactivating inward current abolished by tetrodotoxin (TTX), followed by a slower and slowly-inactivating inward current blocked by calciseptine. The relation between these observations and the unusual 'vertebrate-like' structure of the muscle cells is discussed.
Molecular cloning of a novel brain-type Na(+)-dependent inorganic phosphate cotransporter.
We have isolated a human cDNA encoding a protein, designated DNPI, that shows 82% amino acid identity and 92% similarity to the human brain-specific Na(+)-dependent inorganic phosphate (Na(+)/P(i)) cotransporter (BNPI), which is localized exclusively to neuron-rich regions. Expression of DNPI mRNA in Xenopus oocytes resulted in a significant increase in Na(+)-dependent P(i) transport, indicating that DNPI is a novel Na(+)/P(i) cotransporter. Northern blot analysis shows that DNPI mRNA is expressed predominantly in brain, where the highest levels are observed in medulla, substantia nigra, subthalamic nucleus, and thalamus, all of which express BNPI mRNA at low levels. In contrast, DNPI mRNA is expressed at low levels in cerebellum and hippocampus, where BNPI mRNA is expressed at high levels. No hybridizing signal for DNPI mRNA is observed in the glia-rich region of corpus callosum. In other regions examined, both mRNAs are moderately or highly expressed. These results indicate that BNPI and DNPI, which coordinate Na(+)-dependent P(i) transport in the neuron-rich regions of the brain, may form a new class within the Na(+)/P(i) cotransporter family.
Localization of oxidized HDL in atheromatous plaques and oxidized HDL binding sites on human aortic endothelial cells.
We examined the localization of oxidized high-density lipoprotein (HDL) in atheromatous plaques and the oxidized HDL binding sites on endothelial cells. Histochemical analysis using CuSO4-oxidized HDL-specific 9F5-3a antibody indicated the presence of oxidized HDL in the intima of atheromatous plaques in human abdominal aortae. The cell surface binding of 125I-oxidized HDL to cultured human aortic endothelial cells (HAEC) was saturable, with an apparent dissociation constant (Kd) of 1.43 micromol/L. Competition for 125I-oxidized HDL binding was strong for oxidized HDL, moderate for native HDL and low for acetylated low-density lipoprotein (LDL) or oxidized LDL. Using oxidized HDL as a ligand for blotting, a major 130-kDa band was detected in HAEC. These results suggest that oxidized HDL and its putative binding protein are present in atheromatous plaques and endothelial cells, respectively.
[Usefulness of ultrasonography in a case of spontaneous carotid-cavernous fistula: a case report].
Since spontaneous carotid-cavernous fistula (CCF) is a dural arterio-venous fistula at the cavernous sinus, which is different from traumatic CCF and CCF associated with a ruptured aneurysm at the cavernous internal carotid artery, cerebral angiography is required in order to differentiate these condition. We here report a case of spontaneous CCF, in which a result of ultrasonographic evaluation of cervical arteries well corresponded with that of cerebral angiography. Ultrasonography showed increased blood flow and decreased pulsatility index in the ipsilateral external carotid artery, contralateral internal and external arteries, and these values in all arteries resolved within normal range after the interventional embolization. Ultrasonography is less invasive examination and can be easily performed even in outpatients for observation of spontaneous CCF.
[A case of amoxapine-induced tardive dystonia successfully treated with a low dose anti-cholinergic agent].
We report a 63-year-old man who presented with amoxapine-induced tardive dystonia. At 49 years of age, he developed depression and was administrated 50 mg amoxapine, 4 mg cloxazoram and 3 mg biperiden per day. The daily dose of amoxapine was gradually increased up to 150 mg at 58 years of age. At 61 years of age and after having been taking amoxapine for twelve years, he noticed a rotating left arm and muscle pain in his left shoulder and arm while walking. At 62 years of age, he stopped taking these three drugs. However, the dystonic movements and pain both continued to get worse. Neurological findings revealed no abnormality except for a dystonic posture and movements in the neck and bilateral arms while sitting, standing and walking. Positron emission tomography with C-11 raclopride revealed a mild decrease in the dopamine D 2 receptor numbers in the bilateral striatum. However, two dopamine agonists, pergolide and bromocriptine, worsened his dystonia. In contrast, the daily administration of 2 mg of trihexyphenidyl, an anti-cholinergic agent, markedly ameliorated the dystonia symptoms. As a result, the long-term co-administration of biperiden, an anti-cholinergic agent, may mask the toxicity of amoxapine, which may induce tardive dystonia.
[A patient with limb-girdle type myasthenia gravis and atopic dermatitis, both of which improved after thymectomy].
We herein report a patient with myasthenia gravis (MG) and atopic dermatitis (AD). Heretofore, there have been no reports of patients with MG and AD. Nine years ago, a 25-year-old man noted muscle weakness of upper and lower extremities on physical labor, and the muscle weakness was gradually exacerbated. Two years ago, he noted acute skin eczema with itching on his hands and feet. Neurological examination revealed mild left ptosis, facial muscle weakness and proximal muscle weakness of upper and lower extremities, but no diplopia, ophthalmoplegia or dysphagia. Although anti-nicotinic acetylcholine receptor antibody was negative, edrophonium test was positive and 54% waning in the thenar muscles was observed on Harvey-Masland test. Thus, he was diagnosed as limb-girdle type MG. IgE level in his serum elevated (1,818 U/ml). After thymectomy, the muscle weakness markedly improved as well as waning in the thenar muscles (11%). Simultaneously, AD markedly improved and serum IgE level was decreased (1,245 U/ml). Thus, MG and AD in this case may be derived from some common immunological aberrancy in the thymus.
[Hypertension and reactive oxygen species].
Explore the source record for details and available documents.
[A case of mortor neuron syndrome with onset 9 months after electrical injury].
A 72-year-old man noticed progressive weakness of both upper limbs, more severe on the left side, 9 months after an electric shock of a 20,000 V alternating current. He had diffuse scars of superficial burns with skin graft in four limbs, more on the right side. A neurological examination revealed diffuse muscle atrophy, weakness and fasciculation in both upper limbs, predominantly on the left side, hyper-reflexia in four limbs with mildly exaggerated jaw jerk, left Babinski sign, and mild decrease of touch and pain sensation in the right C6 and C7 segments. Painful dysesthesia was present in the left hand and right lower limb. The search for serum antibodies against GM1, GM2, GM3, GD1a, Gd1b, GQ1b, GA1, and GT1b was negative. No abnormality except mild cervical spondylotic changes was evident in the magnetic resonance imaging of the brain and spinal cord. The upper limb motor evoked potentials (MEPs) were not elicited by the left cortical stimulation and the central motor conduction time by the right cortical stimulation was remarkably prolonged in the upper limb MEPs. Nerve conduction study showed a delay of motor conduction velocity and distal latency in the right median and bilateral ulnar nerves with low amplitude and delayed velocity of sensory nerves of those nerves. Needle EMG revealed diffuse ongoing denervation potentials in bilateral upper limbs and giant motor unit potentials in the right triceps and first dorsal interossei muscles. These findings indicate that the delayed motor neuron syndrome induced by electrical shock is characteristic for having demyelination as well as axonal changes in both central and peripheral nervous systems.
[A patient with motor neuron syndrome clinically similar to amyotrophic lateral sclerosis, presenting spontaneous recovery].
We report a patient with motor neuron syndrome similar to amyotrophic lateral sclerosis (ALS) and with spontaneous recovery. At the age 40, the woman developed progressive muscular weakness, atrophy and fasciculation in extremities. She also noted a dyspnea, tongue atrophy and dysphagia. A neurological examination 6 months after onset revealed i) a tongue atrophy and fasciculation, ii) diffuse muscule weakness and atrophy in face, neck and extremities, and iii) marked hyperreflexia in the four limbs and bilateral Babinski reflex, but iv) neither sensory disturbance nor ophthalmoplegia. Electromyogram (EMG) detected such denervation potentials as fibrillation potentials, fasciculation potentials, positive sharp waves and polyphasic or giant MUPs diffusely in the limb muscles. Peripheral nerve conduction study detected neither conduction block nor delay. Thus, she was diagnosed as suffering from ALS. However, since approximate 1 year after onset, her muscle weakness has gradually been getting better. Simultaneously, the dyspnea and dysphagia gradually improved. Two years after onset, an EMG examination detected chronic denervation potentials in the left musculus sternocleidomastoideus and a few on-going denervation potentials in the left musculus extensor carpi radialis, but no denervation potentials in other limb muscles. Fasciculation potentials were found in tongue muscles. Thus, the present case was thought to have a reversible motor neuron syndrome clinically quite similar to ALS. A mild increase in IgE (346 U/ml) and a low-titer IgM-class anti-GM1 antibody were found in her serum though its pathological significance was uncertain. Any immunological aberrance may account for the pathogenesis. It should be noted that clinically diagnosed cases of ALS may rarely recover spontaneously.
Functional analysis of a mutation occurring between the two in-frame AUG codons of human angiotensinogen.
Angiotensinogen (ANG) is the specific substrate of the renin-angiotensin system, a major participant in blood pressure control. We have identified a natural mutation at the -30 amino acid position of the angiotensinogen signal peptide, in which an arginine is replaced by a proline (R-30P). Heterozygous individuals with R-30P showed a tendency to lowered plasma angiotensinogen level (1563 ng of ANG I/ml (range 1129-1941)) compared with normal individuals in the family (1892 ng of ANG I/ml (range 1603-2072)). Human angiotensinogen mRNA has two in-phase translation initiation codons (AUG) starting upstream 39 and 66 nucleotides from the cap site. R-30P occurs in a cluster of basic residues adjacent to the first AUG codon that may affect intracellular sorting of the nascent protein. Pulse-chase experiments in transiently transfected cultured cells revealed that the R-30P mutation was associated with reduced amounts of both intra- and extracellular protein. In a cell-free system, we found that two forms of native angiotensinogen were generated by alternative initiation of translation at either AUG codon. Alteration of either the first or second AUG codons abolished the synthesis of the longer and the shorter form of native angiotensinogen, respectively. Furthermore, the rate of secretion of the shorter form was lower than that of the longer form. By transplanting angiotensinogen signal peptide onto green fluorescence protein, however, we found that both forms of the signal peptide could target green fluorescence protein, normally localized in the cytoplasm, to the secretory pathway. Although the R-30P mutation may not affect intracellular sorting of angiotensinogen in a qualitative manner, it leads to a quantitative reduction in the net secretion of mature angiotensinogen through decreased translocation or increased residence time in the endoplasmic reticulum.
Reactive oxygen species as a risk factor in verotoxin-1-exposed rats.
It has been suggested the the interaction of Escherichia coli O157-derived verotoxins (VTs) with the vascular endothelium plays a central role in the pathogenesis of the thrombotic microangiopathy and ischemic lesions characteristic of hemolytic uremic syndrome (HUS) and E. coli O157-associated hemorrhagic colitis. Intravenous administration of both E. coli O157-derived VT1 and lipopolysaccharide (LPS) in the rat induced a synergistic increase in thiobarbituric acid (TBA) values in those animal's plasma, as compared with that injected with VT1 or LPS alone. We then hypothesized that an increase in lipid peroxidation in the rat plasma was due to an enhanced production of endothelial cell-derived reactive oxidant. Based on determination of rat sera and cultured human aortic endothelial cells (HAECs), VT1 had little if any effect on LPS-stimulated increase of nitric oxide and the resultant peroxynitrite generations. Both RT-PCR and Western blot studies of reactive oxygen species-related enzymes showed that VT1 markedly decreased the expression of catalase mRNA and protein in HAECs, but caused less alteration in the levels of Cu, Zn-superoxide dismutase, and NADPH oxidase mRNA. Further studies by spin trapping analysis using 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) revealed a time-dependent increase in hydroxyl radicals by VT1 in HAECs. The accumulated data thus suggest that bacterial VT1 reduces mainly catalase levels in endothelial cells, which is synergistically potentiated by LPS, and that the resulting hydroxyl radical participates in endothelium injury through a marked enhancement of lipid peroxidation, leading to HUS.
Loss-of-function and dominant-negative mechanisms associated with hepatocyte nuclear factor-1beta mutations in familial type 2 diabetes mellitus.
Hepatocyte nuclear factor (HNF)-1beta, a homeodomain-containing transcription factor, regulates gene expression in a dimerized form in pancreas, liver, and some other tissues. Recent genetic studies have identified two HNF-1beta mutations, R177X and A263fsinsGG, in subjects with a monogenic form of type 2 diabetes. Despite the defects being in the same gene, diverse severities of disease are observed in the affected subjects. To investigate the molecular mechanism by which mutations might cause various phenotypic features, wild type and mutant proteins were transiently expressed in insulin-producing (MIN6) and hepatic (HepG2) cells. Luciferase reporter assay showed that both mutations resulted in a marked reduction of transactivation activity. Because their dimerization activity was found to be intact by the yeast two-hybrid system, it was possible that they were dominant-negative to wild type activity. When co-expressed with wild type, both of the mutants significantly decreased wild type activity in HepG2 cells. In contrast, although A263fsinsGG functioned similarly in MIN6 cells, R177X failed to affect wild type activity in this cell line. Immunohistochemical analysis of the mutants suggests that this functional divergence might be generated by the modification of nuclear localization. These results suggest that HNF-1beta mutations may impair pancreatic beta-cell function by loss-of-function and dominant-negative mechanisms.
Identification of genes differentially expressed in canine vasospastic cerebral arteries after subarachnoid hemorrhage.
To understand the molecular processes of continuous vasospasm of cerebral arteries after subarachnoid hemorrhage, mRNA differential display and screening of cDNA expression array were performed to identify genes that are differentially expressed in vasospastic arteries of canine two-hemorrhage models. The expression levels of 18 genes were found to be upregulated, and those of two genes to be downregulated. Of these, 12 represent known genes or homologues of genes characterized previously, and the other eight genes are not related to any sequences in the databases. The known genes include five upregulated inflammation-related genes encoding monocyte chemotactic protein-1, cystatin B, inter-alpha-trypsin inhibitor family heavy chain-related protein, serum amyloid A protein, and glycoprotein 130, suggesting that inflammatory reaction may be involved in the development of cerebral vasospasm. The upregulation of three known genes encoding stress-related proteins of vascular endothelial growth factor, BiP protein, and growth-arrest and DNA-damage-inducible protein may be involved in possible cell survival in the damaged arteries. A full-length cDNA for the unknown clone DVS 27, whose expression was most highly upregulated, was isolated from the cerebral artery cDNA library by hybridization. Characterization of these genes should help to clarify the molecular mechanism of continuous cerebral vasospasm after subarachnoid hemorrhage.