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Biomedical subjects

T Miyata

Publications and source records attributed to T Miyata.

At least 307 records · Page 17Linked to original sources
PubMed1997

[Assessment of auscultatory blood pressure measurements versus intra-arterial pressure in patients with atrial fibrillation].

The accuracy of auscultatory blood pressure (BP) determination was assessed in patients with chronic atrial fibrillation by performing simultaneous auscultatory BP determination on the upper arm and a direct BP determination on the contralateral arm. The subjects were three hospitalized patients, aged from 52 to 75 years. A Teflon catheter was introduced into the radial artery which was connected to a pressure transducer, and a cuff was twisted around the contralateral upper arm in the supine position. Simultaneous recording of directly determined BP and cuff pressure enabled the comparison of direct BP with auscultatory BP. The appearance of the Korotkoff I sound (systolic BP) and V sound (diastolic BP) was marked on the cuff pressure curve. This maneuver was repeated five times in each patient. The method of Bland and Altman was employed to assess the agreement between auscultatory and direct determinations. The auscultatory method estimated BP with differences of -14.3 to +27.3 mmHg in systolic BP and -12.1 to +11.9 mmHg (+/-2SD) in diastolic BP compared with the direct method. The difference in systolic BP between the auscultatory and the direct methods was greater than that in diastolic BP. Thus, there are unacceptable differences in systolic BP between auscultatory and direct methods that can be attributed to BP fluctuations. The auscultatory method in diastolic BP is more accurate than that in systolic BP and may be more useful in the clinical setting.

Aged↗
PubMed1996

Immunohistochemical study of advanced glycation end products in aging and Alzheimer's disease brain.

Advanced glycation end products (AGEs) in the brain were immunohistochemically examined in Alzheimer's disease (AD) and aging using anti-AGE antibody recognizing mainly carboxymethyllysine. AGE positive staining diffusely located in the neuronal perikarya of hippocampus and parahippocampus in AD and aged brains without dementia, but not in young brains less than 17 years of age. Extra-neuroperikaryal AGE deposits were also detected in the neuropil of AD and aged brains. The extra-neuroperikaryal AGE deposits markedly increased in AD brains as compared to aged brains. These AGE-positive deposits in the neuropil were not related to the senile plaque identified by anti-beta amyloid protein antibody. These findings suggest a potential link of AGE accumulation in the central nervous system to the aging process of neurons and the degenerating process of AD neurons.

Adolescent↗
PubMed1996

Identification of advanced glycation end products of the Maillard reaction in Pick's disease.

The recent identification of advanced glycation end products (AGEs) of the Maillard reaction in the central nervous system suggests their potential involvement in the aging process. Other studies have also suggested a possible link between AGEs and Alzheimer's disease. To investigate the role of AGEs in Pick's disease, another neurodegenerative disease associated with dementia, we examined the AGE-immunoreaction in Pick's bodies and ballooned neurons, two characteristic neuropathological features of Pick's disease, using antibodies against identified AGE-structures, N epsilon-(carboxymethyl)lysine and pentosidine. These two structures were observed immunohistochemically in Pick's bodies and ballooned neurons of brain tissues obtained at autopsy from three elderly patients diagnosed with Pick's disease. These immunoreactions were further confirmed by absorption experiments and double-immunostaining. The present findings suggest that AGEs are involved in the pathology of Pick's disease.

Aged↗
PubMed1996

Homocysteine-respondent genes in vascular endothelial cells identified by differential display analysis. GRP78/BiP and novel genes.

An elevated blood level of homocysteine is associated with arteriosclerosis and thrombosis. The mechanisms by which homocysteine may promote vascular diseases have not been elucidated yet. In the present study, we have applied a modified nonradioactive differential display analysis to evaluate changes in gene expression induced by homocysteine treatment of cultured human umbilical vein endothelial cells (HUVEC). We identified six up-regulated and one down-regulated genes. One up-regulated gene was GRP78/BiP, a stress protein, suggesting that misfolded proteins would accumulate in the endoplasmic reticulum because of redox potential changes caused by homocysteine. Another up-regulated gene encoded a bifunctional enzyme with activities of methylenetetrahydrofolate dehydrogenase and methenyltetrahydrofolate cyclohydrolase, which is involved in a homocysteine metabolism. A third up-regulated gene encoded activating transcription factor 4, and a fourth was a gene whose function is not identified yet. The remaining three were novel genes. We isolated a full-length cDNA of one of the up-regulated genes from a HUVEC library. It encoded a novel protein with 394 amino acids, which was termed reducing agents and tunicamycin-responsive protein (RTP). Northern blot analysis revealed that RTP gene expression was induced in HUVEC after 4 h incubation with homocysteine. RTP mRNA was also observed in unstimulated cells and induced by not only homocysteine but also 2-mercaptoethanol and tunicamycin. The mRNA was ubiquitously expressed in human tissues. These observations indicate that homocysteine can alter the expressivity of multiple genes, including a stress protein and several novel genes. These responses may contribute to atherogenesis.

Amino Acid Sequence↗
PubMed1996

The receptor for advanced glycation end products (RAGE) is a central mediator of the interaction of AGE-beta2microglobulin with human mononuclear phagocytes via an oxidant-sensitive pathway. Implications for the pathogenesis of dialysis-related amyloidosis.

An important component of amyloid fibrils in dialysis-related amyloidosis is a form of beta2microglobulin modified with advanced glycation end products (AGEs) of the Maillard reaction, known as AGE-beta2M. We demonstrate here that the interaction of AGE-beta2M with mononuclear phagocytes (MPs), cells important in the pathogenesis of the inflammatory arthropathy of dialysis-related amyloidosis, is mediated by the receptor for AGEs, or RAGE. 125I-AGE-beta2M bound to immobilized RAGE or to MPs in a specific, dose-dependent manner (Kd approximately 53.5 and approximately 81.6 nM, respectively), a process inhibited in the presence of RAGE blockade. AGE-beta2M-mediated monocyte chemotaxis was prevented by excess sRAGE or anti-RAGE IgG. Induction of tumor necrosis factor-alpha (TNF) expression by MPs exposed to AGE-beta2M resulted from engagement of RAGE, as appearances of TNF transcripts and TNF antigen release into culture supernatants were prevented by addition of sRAGE, a process mediated, at least in part, by oxidant stress. AGE-beta2M reduced cytochrome c and the elaboration of TNF by MPs was inhibited by N-acetylcysteine. Consistent with these data, immunohistochemical studies of AGE-laden amyloid deposits of a long-term hemodialysis patient revealed positive staining for RAGE in the MPs infiltrating these lesions. These data indicate that RAGE is a central binding site for AGEs formed in vivo and suggest that AGE-beta2M-MP-RAGE interaction likely contributes to the initiation of an inflammatory response in amyloid deposits of long-term hemodialysis patients, a process which may ultimately lead to bone and joint destruction.

Amyloidosis↗
PubMed1996

Distribution of a reeler gene-related antigen in the developing cerebellum: an immunohistochemical study with an allogeneic antibody CR-50 on normal and reeler mice.

We have immunohistochemically investigated the expression of a reeler gene-related antigen in the mouse cerebellum by using a monoclonal antibody, CR-50. This antibody probes a distinct allelic antigen present in normal but not in reeler mutant mice, and this antigen is localized in the brain regions in which morphological abnormalities occur in reeler mice (Ogawa et al., Neuron 14: 899-912, 1995). The developing normal cerebellum showed transient immunoreactivity to CR-50 in a limited set of neurons and in the extracellular space near the pial surface. An early population of CR-50-labeled cells emerged on embryonic day (E) 13 along the dorsal cerebellar surface, comprising the nuclear transitory zone (NTZ). Bromodeoxyuridine labeling revealed the time of origin of these cells to be at E11-12. From E14 to E18, some CR-50-labeled cells were stacked in the inner border of the external granular layer (EGL), whereas others were scattered in deep areas, such as the cerebellar nuclei and the surrounding intermediate zone or white matter. In the first postnatal week, these subcortical structures became immunonegative. However, CR-50 antigen was continuously produced until the second postnatal week by another population of cells occupying i) the premigratory zone (PMZ), the inner half of the EGL, and ii) the internal granular layer (IGL). These later CR-50-positive cells were smaller than the earlier type and showed the morphology typical of granule neurons. Both types of CR-50-labeled cells were positive for a DNA-binding protein, zic. By treating living cerebellar slices with CR-50, the extracellular antigen was localized as a puncutate staining pattern in the NTZ, PMZ, and molecular layer (ML), but not in the subcortical regions and IGL. Purkinje cells were negative for CR-50 and aligned as a monolayer adjacent to the PMZ, though their dendritic trees were closely associated with the extracellular CR-50-antigen in the PMZ and ML. Staining of dissociated cells suggested that the extracellular antigen is initially present throughout the surfaces of the CR-50/anti-zic double positive neurons, and is then rearranged to concentrate on their processes contacting with Purkinje cells. The spatiotemporal expressions of the CR-50 antigen in the cerebellum are consistent with the possibility that this antigen is involved in cell-cell interactions related to the histogenetic assembly of Purkinje cells.

Animals↗
PubMed1996

Mouse-Musashi-1, a neural RNA-binding protein highly enriched in the mammalian CNS stem cell.

There is increasing interest in the role of RNA-binding proteins during neural development. Drosophila Musashi is one of the neural RNA-binding proteins essential for neural development and required for asymmetric cell divisions in the Drosophila adult sensory organ development. Here, a novel mammalian neural RNA-binding protein, mouse-Musashi-1, was identified based on the homology to Drosophila Musashi and Xenopus NRP-1. In the developing CNS, mouse-Musashi-1 protein was highly enriched in the CNS stem cell. Single-cell culture experiments indicated that mouse-Musashi-1 expression is associated with neural precursor cells that are capable of generating neurons and glia. In contrast, in fully differentiated neuronal and glial cells mouse-Musashi-1 expression is lost. This expression pattern of mouse-Musashi-1 is complementary to that of another mammalian neural RNA-binding protein, Hu (a mammalian homologue of a Drosophila neuronal RNA-binding protein Elav), that is expressed in postmitotic neurons within the CNS. In vitro studies indicated that mouse-Musashi-1 possesses binding preferences on poly(G) RNA homopolymer, whereas Hu is known to preferentially bind to short A/U-rich regions in RNA. Based on their differential expression patterns and distinct preferential target RNA sequences, we believe that the mouse-Musashi-1 and Hu proteins may play distinct roles in neurogenesis, either through sequential regulatory mechanisms or differential sorting of mRNA populations during asymmetric division of neural precursor cells.

Amino Acid Sequence↗
PubMed1996

Amino acid sequence and carbohydrate structure of a recombinant human tissue factor pathway inhibitor expressed in Chinese hamster ovary cells: one N-and two O-linked carbohydrate chains are located between Kunitz domains 2 and 3 and one N-linked carbohydrate chain is in Kunitz domain 2.

Human tissue factor pathway inhibitor is a protease inhibitor with three tandem Kunitz-type inhibitory domains. The recombinant protein (r-hTFPI) was produced using Chinese hamster ovary cells, and its polypeptide and carbohydrate chain structures were analyzed. The complete amino acid sequence, composed of 276 residues, was determined using a protein sequencer after protease digestion and it was identical to that predicted from the cDNA sequence. Among three potential N-glycosylation sites, both Asn117 and Asn167 were fully N-glycosylated but Asn228 was not. Thr175 was also fully O-glycosylated, but Ser174 was partially O-glycosylated. Carbohydrate composition and mass spectrometric analyses of the undecapeptide OG-11 (residues Leu 170approximately Leu180) showed that two O-linked carbohydrate chains consisted of a type-1 core structure (Gal-GalNAc-Ser/Thr) with 0-3 mol of N-acetylneuraminic acid(s). The N-linked carbohydrate chains were analyzed by two-dimensional carbohydrate mapping combined with sequential glycosidase digestion, after the reducing-ends of carbohydrate residues were tagged with 2-aminopyridine and non-reducing-end sialic acids were removed with sialidase. All the N-linked structures in r-hTFPI were complex-type carbohydrate chains with one fucose residue attached to the reducing-end GlcNAc and consisted of bi-, tri-, and tetraantennary carbohydrate chains in the ratio 1.9:1.3:1.0. Fucosylated tri- and tetraantennary carbohydrate chains with one or two N-acetyllactosaminyl repeats were also found (30% of carbohydrate chains determined). Thus, the region between Kunitz domains 2 and 3 encoded by exon 7 was highly glycosylated by two O-linked carbohydrate chains at Ser174 and Thr175 and one N-linked carbohydrate chain at Asn167. These results indicated that the region is occupied by a cluster of three bulky and acidic carbohydrate chains.

Amino Acid Sequence↗
PubMed1996

Clinical significance of activated protein C resistance as a potential marker for hypercoagulable state.

The activated protein C (APC)-resistance test is a simple and reliable method for detecting reduced sensitivity to the anticoagulant action of this protein. We investigated the sensitivity to APC in 180 Japanese controls and in 96 Japanese patients with venous and arterial thrombosis (28 with deep vein thrombosis; 13 with pulmonary thromboembolism; 41 with cerebral infarction; and 14 with coronary artery disease). All of the patient groups showed significantly reduced sensitivity to APC, reflected by the lower normalized APC-sensitivity ratio (n-APC-SR), as compared with healthy control. The APC-sensitivity ratio was negatively correlated with plasma activated factor VII levels. These results suggest that the low n-APC-SR is related to venous or arterial thrombotic disease. The APC resistance may serve as a potential marker for assessing the hypercoagulable state.

Adult↗
PubMed1996

Identification of pentosidine as a native structure for advanced glycation end products in beta-2-microglobulin-containing amyloid fibrils in patients with dialysis-related amyloidosis.

beta-2-Microglobulin (beta-2m) is a major constituent of amyloid fibrils in patients with dialysis-related amyloidosis (DRA). Recently, we found that the pigmented and fluorescent adducts formed nonenzymatically between sugar and protein, known as advanced glycation end products (AGEs), were present in beta-2m-containing amyloid fibrils, suggesting the possible involvement of AGE-modified beta-2m in bone and joint destruction in DRA. As an extension of our search for the native structure of AGEs in beta-2m of patients with DRA, the present study focused on pentosidine, a fluorescent cross-linked glycoxidation product. Determination by both HPLC assay and competitive ELISA demonstrated a significant amount of pentosidine in amyloid-fibril beta-2m from long-term hemodialysis patients with DRA, and the acidic isoform of beta-2m in the serum and urine of hemodialysis patients. A further immunohistochemical study revealed the positive immunostaining for pentosidine and immunoreactive AGEs and beta-2m in macrophage-infiltrated amyloid deposits of long-term hemodialysis patients with DRA. These findings implicate a potential link of glycoxidation products in long-lived beta-2m-containing amyloid fibrils to the pathogenesis of DRA.

Amyloid↗
PubMed1996

Rapid growth of hepatocellular carcinoma after or during interferon treatment of chronic hepatitis C: report of three cases.

We report herein the cases of three patients in whom marked rapid growth of hepatocellular carcinoma (HCC) became evident after or during interferon (IFN) treatment for chronic hepatitis C. The HCC tumors were 10, 4.7, and 3.1 cm in size, and were found 7 months, 10 weeks, and 10 weeks after the initiation of IFN, respectively, in cases 1, 2, and 3. The clinical courses of these three patients suggest that the progression of HCC was more rapid during the IFN treatment period. Thus, we propose that abdominal ultrasonic (US) examination should be performed monthly in patients with chronic hepatitis who undergo IFN treatment.

Adult↗
PubMed1996

Use of a nondissection method in lower extremity revascularization: a report on our 12-year experience of autogenous vein bypass surgery.

We report herein on our 12-year experience of performing autogenous vein grafting in the lower extremity using a nondissection method. This method involves limiting preparation for the distal anastomosis to exposure of the anterior surface of the vascular sheath, and substituting an Esmarch's rubber bandage or a pneumatic tourniquet for vascular clamps. A series of 86 consecutive patients who received 101 autogenous vein grafts employing this method were retrospectively analyzed. The causes of arterial occlusion were atherosclerosis in 55 patients, Buerger's disease in 23, and other causes in 9. There was one operative death, and 12 late deaths were recorded within a follow-up period extending to 12 years. Of four early occlusions and two stenoses, three were successfully revised within 30 days of surgery. A total of 11 revision operations were required for 10 grafts during the follow-up period, and late graft closure occurred in 9 bypasses. The primary, primary revised, and secondary patency rates at 5 years for the entire series (n = 101) were 65%, 85%, and 86%, respectively, with 42 bypasses to the tibial or peroneal artery having 84% primary revised and 86% secondary patency rates. These findings led us to conclude that minimization of the surgical injury at the distal anastomosis contributed to the long-term patency of the distal bypass.

Adult↗
PubMed1996

Bleeding gastric varices as a result of splenic vein compression by a celiac arterial aneurysm.

Celiac arterial aneurysms are very unusual and often lack clinical manifestations. According to our review of the literature, this is the first report of a patient with a large celiac arterial aneurysm who exhibited hematemesis from gastric varices. Arteriography, as well as color Doppler ultrasonography and enhanced computed tomography, contributed to the diagnosis of this aneurysm, which was best exposed by a left thoracoabdominal approach. In this patient the lesion was a false aneurysm with perforation of the celiac artery, so simple closure of the orifice was carried out and the revascularization of the celiac artery was not necessary, but we should take care not to ignore the possible recurrence of vascular lesions. The risk of celiac arterial aneurysm rupture is relatively high, but the operative mortality of unruptured aneurysms is now so low that operation is strongly recommended for all patients with this type of aneurysm.

Aneurysm↗
PubMed1996

Local expression of IFN-gamma mRNA in skin lesions of patients with dermatophytosis.

Delayed type hypersensitivity (DTH) response to dermatophyte antigens is one of the host defense mechanisms in dermatophytosis. Skin lesions of dermatophytosis were examined for the cytokine mRNAs expression using the reverse transcriptase/polymerase chain reaction (RT-PCR) method. Interferon-gamma (IFN-gamma) mRNA was expressed in all of the dermatophytosis lesions. IFN-gamma plays an important role in the effector phase of the DTH reaction. Therefore, these findings indicate that DTH response is elicited in the skin lesions with dermatophytosis.

Adult↗
PubMed1996

Alternate repetition of short fore- and backfiltrations reduces convective albumin loss.

An effective therapeutic means to remove relatively large polypeptide uremic toxins seems to be a hemofiltration (HF) or hemodiafiltration (HDF) employing a larger-pore membrane, that is, a protein-permeable membrane. With either method, however, a significant amount of albumin will be lost into the ultrafiltrate or dialysate. Now, repetition of alternate short fore- and backfiltrations may prevent the development of the ultrafiltration-induced higher albumin concentration on the membrane surface (protein concentration polarization), where a single forefiltration time is shorter than the time needed for completion of protein concentration polarization. Since the albumin concentration on the protein-permeable membrane surface will be one of the determinants of albumin loss by convection, such HDF treatment may reduce protein loss into the dialysate. To examine this assumption, we alternately repeated short and rapid fore- and backfiltrations (push/pull HDF) through a protein-permeable membrane, each less than 1 second in duration and at each filtration volume of 15 ml, where a pyrogen-free dialysate was supplied. The present results indicated that the albumin amount lost by push/pull HDF was approximately one-third of that by conventional HDF. Nevertheless, the reduction rates of beta 2-microglobulin and myoglobin were significantly greater by push/pull HDF than by conventional HDF.

Blood Proteins↗