Biomedical subjects

S Uchida

Publications and source records attributed to S Uchida.

At least 91 records · Page 5Linked to original sources

PubMed2001

Blood pressure and heart rate are increased by AF-DX 116, a selective M2 antagonist, in autonomic imbalanced and hypotensive rats caused by repeated cold stress.

Rats exposed to SART (specific alternation of rhythm in temperature) stress, which are ideal animal models for vagotonia-type dysautonomia, show various changes in cardiac and circulatory systems. In this study, attention was directed to cholinergic function in the SART-stressed rat heart and the effects of AF-DX 116, a specific muscarinic M2 antagonist, on blood pressure and heart rate. The results were compared with those obtained for atropine and pirenzepine. In SART-stressed rats, systolic and diastolic blood pressures (SBP and DBP) were lower than in unstressed rats. Oral AF-DX 116 resulted in greater elevation of DBP than SBP in unstressed rats. In stressed rats, greater and more prolonged elevation of SBP than in unstressed rats was noted, particularly at higher doses. A dose-dependent SBP change in stressed rats, caused by intravenous AF-DX 116, was shifted upward in parallel with that in unstressed groups, unlike with oral administration. The positive chronotropic effect of this drug was smaller in stressed rats than in unstressed rats, in contrast to the pressor effect. SART-stressed rats may thus have an enhanced sympathetic tone in the heart, as well as changes in muscarinic M2 receptors at sympathetic nerve endings and at the heart muscle. The effects of AF-DX 116 on blood pressure and heart rate thus may arise from peripheral action and AF-DX 116 may be useful for treating hypotension related to autonomic imbalance of the vagotonia type.

Animals↗

PubMed2001

Effects of a 4.7 T static magnetic field on fetal development in ICR mice.

In order to determine the effects of a 4.7 T static magnetic field (SMF) on fetal development in mice, we evaluated fetal teratogenesis and endochondral ossification following exposure in utero. Pregnant ICR mice were exposed to a 4.7 T SMF from day 7.5 to 9.5 of gestation in a whole-body dose, and sacrificed on day 18.5 of gestation. We examined the incidence of prenatal death, external malformations and fetal skeletal malformations. There were no significant differences observed in the incidence of prenatal death and/or malformations between SMF-exposed mice and control mice. Further, we evaluated the immunoreactivity for the vascular endothelial growth factor (VEGF), which is implicated in angiogenesis and osteogenesis, in the sternum of fetal mice following magnetic exposure. Our studies also indicated that on day 16.5 of gestation following SMF exposure, the immunoreactivity for VEGF was increased compared to unexposed controls. However, it was decreased in the exposed group compared to the control group on day 18.5 of gestation. DNA and proteoglycan (PG) synthesis were also measured in rabbit costal growth plate chondrocytes in vitro. No significant differences were observed in DNA synthesis between the SMF exposed chondrocytes and the control chondrocytes; however, PG synthesis in SMF exposed chondrocytes increased compared to the controls. Based on these results, we suggest that while SMF exposure promoted the endochondral ossification of chondrocytes, it did not induce any harmful effects on fetal development in ICR mice.

Abnormalities, Radiation-Induced↗

PubMed2001

Determination of radionuclides produced by neutrons in heavily exposed workers of the JCO criticality accident in Tokai-mura for estimating an individual's neutron fluence.

In the Tokai-mura criticality accident, three workers were heavily exposed. Biological materials, such as blood, urine, vomit and hair, were collected from the workers and analyzed for radioactivities, produced by the neutron irradiation. Activation products. such as 24Na, -K and 82Br, were found in these materials by gamma-ray spectrometry. The radionuclide of the highest activity observed in biological materials was 24Na, e.g. the concentrations of this nuclide in the blood samples from the three patients at the accident time were 169, 92 and 23 Bq/ml, respectively. The concentrations of stable sodium in the same samples were determined by ICP-AES to obtain specific activities of 24Na (concentration ratio between the produced 24Na and stable 23Na), which are essential for estimating the neutron fluences and radiation doses. The specific activities of 24Na obtained for the three patients through the blood analysis were 8.2 x 10(4),4.3 x 10(4) and 1.2 x 10(4) Bq24Na/g23Na. Based on these values, individual's neutron fluences were estimated to be 5.7 x 10(11), 3.0 x 10(-1) and 0.85 x 10(11) cm(-2), respectively.

Adult↗

PubMed2001

IgA nephropathy with complement deficiency.

We treated a female patient suffering from immunoglobulin A (IgA) nephropathy and congenital deficiency of the ninth component of the complement system (C9). She was admitted with hematuria and proteinuria, and the C9 deficiency was diagnosed based on the low hemolytic activity of 50 % of the hemolytic unit of the complements (CH50) and the normal C3 level in the plasma. Renal biopsy revealed mild mesangial proliferation, and immunofluorescence examination revealed mild mesangial deposits of IgA and C3 with the same distribution. We discuss the pathogenesis of IgA nephropathy and the role of the complements in its progression.

Adult↗

PubMed2001

Treatments of non-parasitic giant hepatic cysts.

This retrospective study presents the results of surgical treatments for large cyst of the liver over 10 cm in diameter in 9 patients diagnosed and treated at Kurume University Hospital. There were 8 women and 1 man, with an average age of 71.6 years. Although the chief complaints were abdominal pain or fullness, 1 had obstructive jaundice due to biliary compression by a large cyst. Cyst size ranged from 10 cm to 27 cm. There are several treatment modalities for giant hepatic cyst, such as cyst resection, unroofing, and sclerotherapy after cyst drainage. Operative procedures in the patients reported here were surgical resection of the liver cyst in 3 patients, unroofing with ethanol sclerotherapy in 1 patient and laparoscopic treatment in 2 patients. Sclerotherapy after percutaneous transhepatic cyst drainage was performed in 3 patients because their general condition was poor. There were no postoperative complications among these patients. Costs varied among the patients and depended mainly on the method of treatment and period of hospital stay. We discuss operative procedures and costs of treatment of each patient and review the literature.

Aged↗

PubMed2001

Expression of angiogenic factors and apoptotic factors in leiomyosarcoma and leiomyoma.

Angiogenesis is essential for tumor growth and metastasis. Some angiogenic factors, such as vascular endothelial growth factor (VEGF), platelet-derived endothelial cell growth factor (PD-ECGF), transforming growth factor-alpha (TGF-alpha) and basic fibroblast growth factor (bFGF) are involved in increased angiogenic activity and disease progression in many carcinomas. However, there is little information regarding the association between angiogenic factors and leiomyosarcoma. Although there are abundant vessels in the sarcoma which enable it to easily receive nutrition and medicinal components, chemotherapy cannot effectively treat leiomyosarcoma. This means the resistance to anticancer drugs in leiomyosarcoma is very strong. However, the resistant mechanism is still unclear. In this study, expressions of VEGF, PD-ECGF, TGF-alpha, bFGF, intratumoral microvessel density (IMVD), and p53, Bcl-2 and Bax were examined by immunohistochemistry in 30 patients with leiomyosarcoma and 21 patients with leiomyoma. With regard to angiogenesis, PD-ECGF and TGF-alpha were closely associated with an increase in IMVD (p=0.012, 0.0196, respectively), and VEGF and PD-ECGF were significantly expressed in leiomyosarcoma compared with leiomyoma (p=0.041, 0.041, respectively). Although p53 expression in leiomyosarcoma was significantly higher than in leiomyoma (p=0.016), the frequency of p53 positivity was not so high (47%). On the other hand, the ratio of Bcl-2/Bax in leiomyosarcoma was significantly higher than that in leiomyoma (p=0.033). The findings of this study suggest that in leiomyosarcoma, angiogenic factors, such as PD-ECGF, VEGF and TGF-alpha expression may be involved in tumor angiogenesis, and the frequently high ratio of Bcl-2/Bax and expression of p53 gene mutation might be related to chemoresistance mechanism.

Angiogenesis Inducing Agents↗

PubMed2001

Two sporadic cases of Liddle's syndrome caused by De novo ENaC mutations.

Liddle's syndrome is a rare form of hereditary hypertension caused by mutations of the epithelial sodium (Na(+)) channel (ENaC). Analysis of the diseased pedigrees indicates an autosomal dominant inheritance, and the identified mutations are heterozygotes of gain-of-function mutations. However, sporadic cases of Liddle's syndrome have been reported in the literature, including one recently reported case caused by a de novo mutation of ENaC. We identified two patients with Liddle's syndrome who did not have family histories of hypertension. Sequence analysis showed a mutation in each case (P616L in betaENaC and W576X in gammaENaC), both confirmed to be de novo mutations. These data indicate that Liddle's syndrome should be considered even in patients without a family history of hypertension.

Adult↗

PubMed2001

The role of the human lateral pterygoid muscle in the control of horizontal jaw movements.

There is a limited understanding of the normal function of the lateral pterygoid muscle (LP) and the role that this muscle plays in temporomandibular disorders. This article addresses the hypothesis that a major function of the LP is in the control of horizontal jaw movements. The range of fiber alignments suited to generating a major horizontal force vector (magnitude and direction), together with the likelihood of independent activation of subcompartments (that is, functionally heterogeneous zones) within each head, provide the possibility of a finely graded range of force vectors on the condyle to effect the fine control of horizontal jaw movements. This level of control does not appear to extend to the control of resting jaw posture, as recent single motor unit (SMU) data indicate that the LP is inactive with the jaw in the postural jaw position. Available electromyographic data demonstrate graded changes in multiunit and SMU activity with small horizontal jaw displacements at low force levels, a single preferred direction of the SMU firing rate during horizontal isometric jaw tasks, and graded changes in the SMU firing rate with horizontal force magnitude and direction. The evidence suggests that a major function of the LP is in the generation and fine control of the horizontal component of jaw movement by the graded activation of a subset of SMUs within the LP. The data also suggest that the LP is involved in the generation of horizontal force vectors, as required in parafunctional activities and heavy mastication.

Electromyography↗

PubMed2000

Isolation and characterization of the human CLC-5 chloride channel gene promoter.

The human CLC-5 chloride channel is expressed mainly in the kidney and its mutations cause Dent's disease (a familial renal tubular syndrome with hypercalciuria, tubular proteinuria, rickets, nephrocalcinosis, and eventual renal failure). To gain insight into the regulatory mechanism of CLC-5 expression, a genomic clone that contains the 5'-flanking region of the human CLC-5 gene was isolated and characterized. Two types of 5'-ends of cDNA were isolated by 5'-rapid amplification of cDNA ends, and one of them, approximately 2.1 kbp upstream of ATG-containing exon II, was first identified in human. The major promoter activity was detected in the 5'-flanking region of this newly identified exon Ia. The sequence of the proximal 5'-flanking region contained an activator protein (AP)-1-like site and cAMP-responsive element, but it lacked a TATA box, a GC-rich element, and an SP-1 site. Deletion analysis of the 5'-flanking region showed that the fragments containing the AP-1-like element (TGACTCC) positioned at -38 exhibited high promoter activities in CLC-5 expressing LLC-PK1 cells, but that further deletions not containing this AP-1-like element resulted in a great loss of luciferase activities. Gel-retardation analysis demonstrated the existence of a specific protein binding to this AP-1-like element in LLC-PK1 cells, which seemed to differ from an authentic AP-1. This study clarified the key element of the human CLCN5 promoter, and the mutation in this region could be the cause of Dent's disease.

Animals↗

PubMed2000

Angle-resolved photoemission study of insulating and metallic Cu-O chains in PrBa2Cu3O7 and PrBa2Cu4O8

We compare the angle-resolved photoemission spectra of the hole-doped Cu-O chains in PrBa2Cu3O7 (Pr123) and in PrBa2Cu4O8 (Pr124). While, in Pr123, a dispersive feature from the chain takes a band maximum at k(b) (momentum along the chain) approximately pi/4 and loses its spectral weight around the Fermi level, it reaches the Fermi level at k(b) approximately pi/4 in Pr124. Although the chains in Pr123 and Pr124 are approximately 1/4 filled, they show contrasting behaviors: While the chains in Pr123 have an instability to charge ordering, those in Pr124 avoid it and show an interesting spectral feature of a metallic coupled-chain system.

Journal Article↗

PubMed2000

Effects of age on cholinergic vasodilation of cortical cerebral blood vessels in rats.

The present study examined the age-related changes in the cholinergic vasodilative system originating in the nucleus basalis of Meynert (NBM) and projecting to the cerebral cortex using Wistar rats of three different ages; young adult (4-7 months), old (24-25 months), and very old (32-42 months) rats. The vasodilative responses in frontal and parietal cortices, measured by laser Doppler flowmetry, induced by electrical stimulation of NBM without blood pressure response were well maintained in old rats, but declined significantly in very old rats. Extracellular acethylcholine (ACh) release in both cortices collected by a microdialysis technique showed both basal levels and response to NBM stimulation to be well maintained in both old and very old rats. The vasodilative cerebral blood flow response elicited by stimulation of the muscarinic ACh receptors, using their agonist, arecoline, was also well maintained in old and very old rats. Considering the present data and our previous finding that the cerebral cortical vasodilative response to activation of the nicotinic ACh receptors using their agonist, nicotine, was markedly reduced in very old rats (Neurosci. Lett., 228 (1997) 203), it was concluded that the age-related decline of nicotinic ACh receptor activity was a cause of the decline of the vasodilative responses elicited by NBM stimulation in very old rats. This result suggests that a reduction of the cholinergic vasodilative system in very old rats due to decreased activity of the nicotinic ACh receptor may cause insufficient blood flow in the cortex when the cortical neurons require.

Acetylcholine↗

PubMed2000

Neurotrophic function of conditioned medium from human amniotic epithelial cells.

Human amniotic epithelial cells (HAEC) may have pluripotent function because they are formed from the epiblast cells at the 8th day of fertilization. Previously, we reported that HAEC have the capacity to synthesize and release acetylcholine and catecholamine associated with the binding sites of catecholamine receptors. We show the neurotrophic function of a conditioned medium from HAEC using cultured cortical neurons of E18 rats. Extensive analyses with various techniques demonstrated that HAEC and immortalized HAEC synthesize and release brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and nerve growth factor (NGF). Other neurotrophic factors were not detected in a cultured medium of HAEC by enzyme immunoassay. Various neurotrophic factors or growth factors did not show neurotrophic effects on E18 rat neuron except for EGF. Because EGF was not detected in the conditioned medium of HAEC, these data indicate an unidentified neurotrophic factor presently that is synthesized and released from HAEC. The amniotic membrane may have a significant role in supplying neurotrophic factors to the amniotic fluid as well as neurotransmitters, suggesting an important function to the early stages of neural development in the embryo.

Amniotic Fluid↗

PubMed2000

Ultrafast optical nonlinearity in the quasi-one-dimensional mott insulator Sr2CuO3

We report strong instantaneous photoinduced absorption in the quasi-one-dimensional Mott insulator Sr2CuO3 in the IR spectral region. The observed photoinduced absorption is to an even-parity two-photon state that occurs immediately above the absorption edge. Theoretical calculation based on a two-band extended Hubbard model explains the experimental features and indicates that the strong two-photon absorption is due to a very large dipole coupling between nearly degenerate one- and two-photon states. Room temperature picosecond recovery of the optical transparency suggests the strong potential of Sr2CuO3 for all-optical switching.

Journal Article↗

PubMed2000

Local magnetic order vs superconductivity in a layered cuprate

We report on the phase diagram for charge-stripe order in La1.6-xNd0. 4SrxCuO4, determined by neutron and x-ray scattering studies and resistivity measurements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition temperature for local charge ordering decreases monotonically with x, and hence that local antiferromagnetic order is uniquely correlated with the anomalous depression of superconductivity at x approximately 1 / 8. This result is consistent with theories in which superconductivity depends on the existence of charge-stripe correlations.

Journal Article↗

PubMed2000

STM studies of the electronic structure of vortex cores in Bi(2)Sr(2)CaCu(2)O(8+delta)

We report on low temperature scanning tunneling microscopy (STM) studies of the electronic structure of vortex cores in Bi 2Sr 2CaCu 2O (8+delta). At the vortex core center, an enhanced density of states is observed at energies near Omega = +/-7 meV. Spectroscopic imaging at these energies reveals an exponential decay of these "core states" with a decay length of 22+/-3 A. The fourfold symmetry sometimes predicted for d-wave vortices is not seen in spectroscopic vortex images. A locally nodeless order parameter induced by the magnetic field may be consistent with these measurements.

Journal Article↗

PubMed2000

Vortex-like excitations and the onset of superconducting phase fluctuation in underdoped La(2-x)Sr(x)CuO4

Two general features of a superconductor, which appear at the critical temperature, are the formation of an energy gap and the expulsion of magnetic flux (the Meissner effect). In underdoped copper oxides, there is strong evidence that an energy gap (the pseudogap) opens up at a temperature significantly higher than the critical temperature (by 100-220 K). Certain features of the pseudogap suggest that it is closely related to the gap that appears at the critical temperature (for example, the variation of the gap magnitudes around the Fermi surface and their maximum amplitudes are very similar). However, the Meissner effect is absent in the pseudogap state. The nature of the pseudogap state, and its relation (if any) to the superconducting state are central issues in understanding copper oxide superconductivity. Recent evidence suggests that, in the underdoped regime, the Meissner state is destroyed above the critical temperature by strong phase fluctuations (as opposed to a vanishing of the superfluid density). Here we report evidence for vortices (or vortex-like excitations) in La(2-x)Sr(x)CuO4 at temperatures significantly above the critical temperature. A thermal gradient is applied to the sample in a magnetic field. Vortices are detected by the large transverse electric field produced as they diffuse down the gradient (the Nernst effect). We find that the Nernst signal is anomalously enhanced at temperatures as high as 150 K.

Journal Article↗

PubMed2000

Isolation and characterization of a novel liver-specific gene, hepassocin, upregulated during liver regeneration.

By differential cDNA cloning coupled with Xenopus oocyte expression screening, we isolated a cDNA encoding a novel protein, termed 'hepassocin', the expression of which is upregulated in the regenerating rat liver. The cDNA contained a single open reading frame encoding a protein of 314 amino acids (ca. 34 kDa), including 24 amino acids of signal sequence. The protein expressed from the cDNA in Verots cells had activity to stimulate DNA synthesis in primary rat hepatocytes and was of 66 kDa or 34 kDa, under non-reducing or reducing conditions, respectively. Using an affinity column conjugated with the antibody raised against a peptide in a hydrophilic region, we purified hepassocin from the rat liver: it had a DNA synthesis-stimulating activity in hepatocytes. The hepassocin obtained here was 66 kDa, and the 34 kDa protein obtained under reducing conditions contained five cysteine residues, indicating that hepassocin is active as a homodimer. Northern blot analysis revealed that hepassocin mRNA (1.4 kb in length) occurred only in the liver, and in situ hybridization studies revealed its presence in parenchymal hepatocytes but not in endothelial cells. Furthermore, the expression of hepassocin mRNA was upregulated during compensatory hyperplasia after partial hepatectomy and regeneration after galactosamine treatment in the rat liver. These results suggest that hepassocin plays an important role in stimulating liver cell growth, through an autocrine mechanism.

Amino Acid Sequence↗

PubMed2000

A new SUMO-1-specific protease, SUSP1, that is highly expressed in reproductive organs.

A full-length cDNA encoding a SUMO-1-specific protease, named SUSP1, was identified and cloned for the first time from the human brain. Nucleotide sequence analysis of the cDNA containing an open reading frame of 3336 base pairs revealed that the protease consists of 1112 amino acids with a calculated molecular mass of 126,116 Da. Like yeast Ulp1, SUSP1 is a cysteine protease containing the well conserved His/Asp/Cys catalytic triad. SUSP1 expressed in Escherichia coli cells efficiently released SUMO-1 from SUMO-1. beta-galactosidase fusion but not from other ubiquitin-like protein fusions, including Smt3.beta-galactosidase, suggesting its role in the generation of matured SUMO-1 specifically from its precursors. Interestingly, reproductive organs, such as testis, ovary, and prostate, contained much higher amounts of SUSP1 mRNA than colon and peripheral blood leukocyte, whereas other tissues, such as heart and spleen, had little or none. In addition, confocal microscopy using green fluorescent protein.SUSP1 fusion showed that SUSP1 is exclusively localized to the cytoplasm of NIH3T3 and HeLa cells. These results suggest that SUSP1 may play a role in the regulation of SUMO-1-mediated cellular processes particularly related to reproduction.

Amino Acid Sequence↗