Biomedical subjects

H Sato

Publications and source records attributed to H Sato.

At least 127 records · Page 7Linked to original sources

PubMed2002

Activation of prostaglandin E2-receptor EP2 and EP4 pathways induces growth inhibition in human gastric carcinoma cell lines.

The effect of prostaglandin E2 (PGE2) on the proliferation of gastric cancer cells is still unclear. PGE2 receptors are divided into four subtypes - EP1, EP2, EP3, and EP4 - which are coupled to three different intracellular signal-transduction systems. Stimulation of EP2 and EP4 is linked with cyclic adenosine 3', 5'-monophosphate (cAMP)-dependent protein kinase A (PKA). In some human gastric cancer cells, PGE2 has been suggested to have an antiproliferative effect by way of increased cAMP production. Expression of EP2 and EP4 in human gastric carcinoma cells, however, has not been examined. We examined the expression of EP2 and EP4 and the antiproliferative effects of specific EP2 and EP4 agonists on four different human gastric cancer cell lines. Our data clarified that all the cell lines investigated in this study expressed EP2 and EP4 and that the specific agonists of these receptors induced growth inhibition with an accompanying increase in cAMP production. In summary, gastric cancer cells have EP2 and EP4 receptors, and their selective activation is linked with the decreased cell proliferation.

Cell Division↗

PubMed2002

Notch3 gene polymorphism and ischaemic cerebrovascular disease.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a type of hereditary stroke and dementia. More than 90% of patients with CADASIL have mutations in the Notch3 gene. All mutations either create or destroy a cysteine residue in the epidermal growth factor-like repeats. In addition, five polymorphisms, which lead to amino acid substitutions, have been identified within the Notch3 coding sequence. However, whether these polymorphisms affect Notch signalling or are involved in cerebrovascular diseases is unknown. In the present study, we investigated a possible association between a T6746C polymorphism in the Notch3 coding region and the occurrence of symptomatic ischaemic cerebrovascular disease (CVD) was investigated. Two hundred and thirty five patients with CVD, as confirmed by brain CT or MRI, and 315 age and sex matched control subjects were analyzed for genotype frequencies of the T6746C polymorphism in Notch3. The genotype distributions were: patients with CVD, C/C 14.0%, C/T 45.5%, and T/T 40.4%; controls, C/C, 14.3%; C/T, 47.9%; T/T, 37.8%. The Japanese population has a higher C allele frequency of the T6746C polymorphism than European populations. There was no significant difference between the T6746C polymorphism in patients with CVD and controls (chi(2)=0.414, p=0.813). This was confirmed by the results of multiple logistic regression analysis including established risk factors (chi(2) =4.65, p=0.311). In conclusion, the results indicate that T6746C polymorphism in the intracellular domain of the Notch3 gene is not associated with an increased risk for CVD.

Aged↗

PubMed2002

Peripheral mechanisms in tremor after traumatic neck injury.

Tremor is a rare manifestation after neck injury, and its physiological mechanism has not been elucidated. We studied the effects of torque loading and ischaemic nerve block on coarse postural tremor in the right upper extremity, which had developed in association with a C7-C8 radiculopathy after traumatic neck injury in a 55 year old man. Loading reduced the tremor frequency from 6.1 Hz to 4.2 Hz with corresponding electromyography (EMG) bursts at the same frequencies as the tremor. Ischaemic nerve block also reduced the tremor frequency from 6.2 Hz to 2.8 Hz, and the time course of the frequency was not in parallel with that of the size of the maximal M wave. A significant reduction of the tremor frequency by loading and ischaemic nerve block indicates a mechanical reflex mechanism underlying the tremor, and association of synchronous EMG bursts suggests an increase in gain in the stretch reflex loop. The stretch reflex loop plays an important role in generation of oscillation in tremor after neck injury.

Cervical Vertebrae↗

PubMed2002

Mutagenesis by environmental pollutants and bio-monitoring of environmental mutagens.

There is serious concern about the adverse effects of environmental pollutants on human health. Various mutagens, which pollute air, water, and food, possibly induce mutations in humans, and are suspected of causing cancer. Environmental mutagens, such as polycyclic aromatic hydrocarbons (PAH) and heterocyclic amines are known to bind to nucleotides, resulting in the formation of DNA adducts. Some DNA adducts are fixed as mutations through replication of DNA. Reactive oxygen species generated by pollutants also induce the formation of DNA adducts. DNA adducts have been detected as a marker for the exposure of humans and wild life to mutagens. Because of its high sensitivity the 32P-postlabel-thin layer chromatography (TLC) method is widely used for the analysis of DNA adducts formed by PAH and related bulky compounds. However, new systems are required for detecting mutations induced in genomic DNA in vivo to monitor environmental mutagens. Recently, transgenic animals, in which a target gene for detecting mutations is integrated, have been developed. With these transgenic animals, not only mutant frequency but mutation spectra can be determined. We review here recent advances in the detection of DNA adducts formed by environmental pollutants and their application for biological monitoring of environmental mutagens. We also discuss transgenic animals as important tools for evaluating the total mutagenic potential of environmental chemicals.

Animals↗

PubMed2002

[Unruptured aneurysm of the noncoronary sinus of Valsalva protruded into the left atrium; report of a case].

A successful operative treatment of an unruptured aneurysm of the noncoronary sinus of Valsalva protruded into the left atrium is reported. A 64-year-old female was unexpectedly found an aneurysm of the sinus of Valsalva during the examination of bradycardia. Cardiac angiography and two dimensional echocardiography demonstrated the unruptured aneurysm of the noncoronary sinus of Valsalva of 35 mm in diameter, which protruded into the left atrium. She underwent the surgery. The aneurysm was excised and the aortic root defect was closed with a Woven dacron patch. The postoperative course was uneventful. Pathologic examination revealed the atherosclerotic change of the aorta. As far as we know, this patient is the first reported case of the unruptured aneurysm of the noncoronary sinus of Valsalva protruded into the left atrium in this country.

Aortic Aneurysm↗

PubMed2001

99.6% spin-flip efficiency in the presence of a strong Siberian snake.

We recently studied the spin-flipping efficiency of an rf-dipole magnet using a 120-MeV horizontally polarized proton beam stored in the Indiana University Cyclotron Facility Cooler Ring, which contained a nearly full Siberian snake. We flipped the spin by ramping the rf dipole's frequency through an rf-induced depolarizing resonance. By adiabatically turning on the rf dipole, we minimized the beam loss. After optimizing the frequency ramp parameters, we used 100 multiple spin flips to measure a spin-flip efficiency of 99.63+/-0.05%. This result indicates that spin flipping should be possible in very-high-energy polarized storage rings, where Siberian snakes are certainly needed and only dipole rf-flipper magnets are practical.

Journal Article↗

PubMed2001

Neurogenesis of heterotopic gray matter in the brain of the microcephalic mouse.

Neurogenesis of heterotopic gray matter in the brain of the microcephalic mouse prenatally exposed to X-rays at embryonic day 13 (E13) was studied immunohistochemically. Bromodeoxyuridine (BrdU) as a marker to label the migrating position of neuroblasts generated at various embryonic stages showed that no "inside-out" pattern of neuronal migration occurred in the heterotopic cell mass similar to that seen in the laminated cortex. Further results in which midkind (MK) immunoreactive radial glial fibers did not appear in the heterotopic cell mass demonstrated that heterotopia formed in the absence of radial glia system. Different types of cells (pyramidal and non-pyramidal neurons) in the heterotopic cell mass were identified with immunoreactivity for anti-parvalbumin and anti-calbindin D-28K antibodies in addition to current histological methods. Two major types of neurons were mixed together with random distribution in the heterotopic cell mass. This finding indicates that irradiation might have no selective effects on the precursors of pyramidal and non-pyramidal neurons. Moreover, anti-glial fibrillary acidic protein (GFAP) immunostaining showed that numerous astrocytes were present in the heterotopic cell mass. The fact that astrocytes appeared in the heterotopia without the transition from classic radial glial cells to astrocytes suggests that astrocytes might be generated directly from a separate astroglial precursor.

Animals↗

PubMed2001

Suppression of membrane-type 1 matrix metalloproteinase (MMP)-mediated MMP-2 activation and tumor invasion by testican 3 and its splicing variant gene product, N-Tes.

Using expression cloning to screen a human fetal kidney cDNA library for regulator(s) of pro-matrix metalloproteinase (MMP)-2 processing mediated by membrane-type (MT) 1 MMP, we isolated a cDNA whose product interfered with pro-MMP-2 activation. It encodes the NH(2)-terminal 313-amino acid region of a calcium-binding proteoglycan, testican 3, with a 3-amino acid substitution at the COOH terminus and thus was named N-Tes. N-Tes comprises a signal peptide, a unique domain, a follistatin-like domain, and a Ca(2+)-binding domain but lacks a COOH-terminal thyroglobulin domain and two putative glycosaminoglycan attachment sites of testican 3. Pro-MMP-2 activation by MT3-MMP was also inhibited by the coexpression of N-Tes. Immunoprecipitation analysis demonstrated direct interaction of N-Tes with either MT1-MMP or MT3-MMP. Expression of testican 1 or testican 3 but not testican 2 also inhibited pro-MMP-2 activation by either MT1-MMP or MT3-MMP. Deletion and substitution of amino acids residues in N-Tes revealed that the unique NH(2)-terminal domain of N-Tes is responsible for the inhibition of pro-MMP-2 activation by MT-MMPs. Expression of N-Tes and testican 3 was detected in normal brain but down-regulated in glioma tissues. Transfection of either the N-Tes or testican 3 gene into U251 glioma cells or Madin-Darby canine kidney cells transformed by erbB2 suppressed their invasive growth in collagen gel. These results suggest that both N-Tes and testican 3 would interfere with tumor invasion by inhibiting MT-MMPs.

Alternative Splicing↗

PubMed2001

Acidic fibroblast growth factor (FGF-1) in the anterior horn cells of ALS and control cases.

The expression and localization of acidic fibroblast growth factor (aFGF; FGF-1) were examined in the spinal cord of patients with amyotrophic lateral sclerosis (ALS) and controls by reverse transcription-polymerase chain reaction (RT-PCR) method and immunohistochemistry. The RT-PCR experiments demonstrated that aFGF amplification products were clearly detected in all control cases but could be scarcely seen in ALS patients. aFGF immunoreactivity was detected in the anterior horn cells of the spinal cord. Double immunostaining for aFGF and choline acetyltransferase revealed that the majority (95.9%) of cholinergic neurons expressed aFGF. In ALS cases, the number and the staining intensity of aFGF-positive neurons were markedly decreased. These results suggest that aFGF is involved in ALS pathology.

Acetylcholine↗

PubMed2001

Expression of dominant-negative form of Ets-1 suppresses fibronectin-stimulated cell adhesion and migration through down-regulation of integrin alpha5 expression in U251 glioma cell line.

Ets transcription factors are associated with tumor malignancy. We reported previously that the stable transfection of the dominant-negative form of Ets-1 (Ets-DN) in the glioma cell line U251 induced down-regulation of urokinase-type plasminogen activator mRNA expression and invasiveness (M. Nakada et al., J. Neuropathol. Exp. Neurol., 58: 329-334, 1999). Here we analyzed effects of Ets-DN expression on cell adhesion, migration, and phosphorylation of focal adhesion kinase. U251 cells expressing Ets-DN (U251-DN) showed reduced cell adhesion, spreading, and extension of actin stress fibers on dishes coated with fibronectin but not on dishes coated with collagen. Migration of U251-DN cells was found to be significantly inhibited compared with that of parental cells when examined by wound-induced migration assay on fibronectin-coated dishes. Phosphorylation levels of focal adhesion kinase in U251-DN cells were also attenuated on dishes coated with fibronectin. Reduced expression level of integrin alpha5 subunit in U251-DN cells was demonstrated by semiquantitative reverse transcription-PCR analysis. Semiquantitative reverse transcription-PCR of surgical samples of brain tumors revealed that the expression level of Ets-1 mRNA correlated with that of integrin alpha5 mRNA in glioma. The experimental metastatic ability of U251-DN cells examined in chick embryo was considerably lower than that of parental cells. These results suggest that Ets-1 contributes to glioma malignancy by up- regulating expression of the integrin alpha5 subunit, which composes integrin alpha5beta1 and mediates intracellular signaling and the subsequent acceleration of the invasive process, including cell adhesion and migration.

Animals↗

PubMed2001

Genomic organization and transcription units of the human acyl-CoA synthetase 3 gene.

Acyl-CoA synthetases (ACSs) play an essential role in fatty acid metabolism. ACS3 is an arachidonate-preferring enzyme expressed in a wide range of human tissues including brain, heart, placenta, prostate, skeletal muscle, testis and thymus. As an initial step to understanding the transcriptional regulation of the human ACS3 gene, we analyzed the genomic organization and transcription units of the human ACS3 gene. Sequence analysis of genomic clones demonstrates that the human ACS3 gene spans at least 80.6 kb and contains 17 exons. The human ACS3 gene was mapped between the sequence-tagged site markers D2S360 and WI-21901. Sequence inspection of the 5'-flanking region revealed potential DNA elements including CCAAT, AP-1, Oct-1, GATAs, SRY, CdxA, Nkx-2.5, c-Myb, HSF2, NF-AT, AP-2, NF-Y, and p300. A minimal promoter region required for the expression of the human ACS3 gene in melanoma G361 cells was determined.

5' Flanking Region↗

PubMed2001

Human breast cancer MDA-MB-231 cells fail to express the neurofibromin protein, lack its type I mRNA isoform and show accumulation of P-MAPK and activated Ras.

Neurofibromin is a tumor suppressor protein, which is similar in function to the GTPase activating protein (GAP), p120GAP, in that it accelerates inactivation of Ras. Mutations in the NF1 gene cause neurofibromatosis type 1, NF1, an autosomal dominant disease with a diverse spectrum of clinical manifestations, including neurofibromas. Ras activation (GTP binding) is induced by the GTP exchange factor Sos and its inactivation is regulated through the GAPs (p120GAP and neurofibromin). Strikingly, neurofibromin was nearly absent in MB-231 human breast cancer cells and present in the remaining four cell lines studied, with higher levels in BT-474 and MB-453 than in MCF-7 and BT-20 cells, as tested with polyclonal antibodies to both the N-terminal as well as the C-terminal peptides. Coordinated with the near absence of neurofibromin, these cells also presented with much greater levels of P-MAPK and activated Ras. Further, RT-PCR analysis demonstrated the absence of expression of NF1 mRNA type I isoform only in the MB-231 cell lines. This result documents for the first time an altered NF1 expression at the protein and mRNA levels in MDA-MB-231 breast cancer cells.

Animals↗

PubMed2001

Otolith-activated vestibulothalamic neurons in cats.

The components of the vestibular ascending pathway that transmit otolith information to the thalamus were studied electrophysiologically in anesthetized cats. Thalamic-projecting vestibular neurons (confirmed antidromically) were recorded extracellularly in the various vestibular nuclei. Otolith inputs to these neurons were examined with selective stimulation of the utricular (UT) or the saccular (SAC) nerves. Vestibular nerve branches other than the tested nerve were transected. Of 40 UT-activated vestibulothalamic neurons, 40% (16/40) were activated by UT nerve stimulation with latencies ranging between 0.9-1.4 ms, suggesting they were second-order neurons from the UT nerve. UT-activated vestibulothalamic neurons were recorded in the medial vestibular nucleus (MVN; 24/40), the lateral vestibular nucleus (LVN; 9/40), the descending vestibular nucleus (DVN; 6/40), and the superior vestibular nucleus (SVN; 1/40). Most of the neurons (38/40) were antidromically activated by focal stimulation of the ventral part of the ipsilateral thalamus. Antidromic stimulation of the pontine area revealed that trajectories of the ascending axons (14 of 38 neurons) to the ipsilateral thalamus passed through the pontine reticular formation, ventral to the ascending tract of Deiters (ATD) and the medial longitudinal fasciculus (MLF). Only three SAC-activated vestibulothalamic neurons were encountered in the LVN. All these neurons were second-order neurons from the SAC nerve and were antidromically activated by stimulation of the contralateral thalamus, in marked contrast to the UT-activated vestibulothalamic neurons. Only three UT-activated and two SAC-activated neurons sent descending collaterals to the spinal cord.

Action Potentials↗

PubMed2001

Practical asymmetric synthesis of a selective endothelin A receptor (ETA) antagonist.

[structure: see text]. A practical, chromotography-free asymmetric synthesis was developed for the large scale preparation of an endothelin receptor antagonist 2. This synthesis includes a new efficient process for the preparation of 6-bromo-2,3-dihydrobenzofuran, a stereoselective conjugate addition of an aryllithium followed by stereospecific addition of the Grignard reagent of the top aryl bromide, and an aminophosphate-mediated sterospecific intramolecular enolate alkylation, which led to the formation of the five-membered ring bearing three contiguous asymmetric centers.

Antihypertensive Agents↗

PubMed2001

Quantitative changes in glycosaminoglycans in the lungs of rats exposed to diesel exhaust.

Exposure to diesel exhaust (DE) induces lesions in lung epithelium by generation of reactive oxygen species. Glycosaminoglycans (GAG), components of extracellar matrix, are thought to play important roles in cell proliferation and differentiation in the repair process of injured tissue. We investigated how GAG are related to the recovery of lung tissue from injury. Using high-performance liquid chromatography analysis, we determined the amounts of GAG, such as chondroitin sulfate (CS), dermatan sulfate (DS), and hyaluronan (HA) in the lungs of rats exposed to DE for 4 weeks at concentrations of 0.3 or 3 mg/m(3) as suspended particulate matter, or to filtered air. The contents of CS and HA in the surroundings of the bronchi were significantly increased after exposure to DE. In addition, immunohistochemical staining showed that the number of 8-hydroxydeoxyguanosine-positive cells as a marker of cell damage, and proliferating cell nuclear antigen-positive cells also increased in the same areas in which the levels of GAG were elevated in the lungs of rats exposed to 3 mg/m(3) DE. These results suggest that CS and HA in the lung contribute to cell proliferation and remodeling in the process of recovery from injury caused by exposure to DE.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

Intracerebroventricular injection of pipecolic acid inhibits food intake and induces sleeping-like behaviors in the neonatal chick.

It has been demonstrated that L-pipecolic acid (L-PA), a major metabolic intermediate of L-Lysine (L-Lys) in the brain, is involved in the functioning of Gamma-aminobutyric acid. In the present work the effect of intracerebroventricular (i.c.v.) administration of L-PA, and its relatives, on food intake and behavior in neonatal chicks was investigated. The i.c.v. injection of 1 mg of L-PA and D-PA significantly inhibited food intake during the 2 h following injection, whereas greater than 2 mg of L-Lys was required to inhibit food intake. In behavioral tests, the i.c.v. injection of L-PA reduced active wakefulness and feeding behavior while inducing sleeping-like behavior in chicks. These results suggest that L-PA has an important role for the regulation of behaviors in the neonatal chick after conversion from L-Lys in the brain.

Age Factors↗

PubMed2001

Homophilic complex formation of MT1-MMP facilitates proMMP-2 activation on the cell surface and promotes tumor cell invasion.

Activation of proMMP-2 by MT1-MMP is considered to be a critical event in cancer cell invasion. In the activation step, TIMP-2 bound to MT1-MMP on the cell surface acts as a receptor for proMMP-2. Subsequently, adjacent TIMP-2-free MT1-MMP activates the proMMP-2 in the ternary complex. In this study, we demonstrate that MT1-MMP forms a homophilic complex through the hemopexin-like (PEX) domain that acts as a mechanism to keep MT1-MMP molecules close together to facilitate proMMP-2 activation. Deletion of the PEX domain in MT1-MMP, or swapping the domain with the one derived from MT4-MMP, abolished the ability to activate proMMP-2 on the cell surface without affecting the proteolytic activities. In addition, expression of the mutant MT1-MMP lacking the catalytic domain (MT1PEX-F) efficiently inhibited complex formation of the full-length enzymes and activation of pro MMP-2. Furthermore, expression of MT1PEX-F inhibited proMMP-2 activation and Matrigel invasion activity of invasive human fibrosarcoma HT1080 cells. These findings elucidate a new function of the PEX domain: regulating MT1-MMP activity on the cell surface, which accelerates cellular invasiveness in the tissue.

Animals↗

PubMed2001

Simultaneous determination of six adenyl purines in human plasma by high-performance liquid chromatography with fluorescence derivatization.

A sensitive method was developed for the simultaneous determination of six adenyl purines in human plasma by high-performance liquid chromatography. The adenyl purines (adenine, adenosine, AMP, ADP, ATP and cyclic AMP) were derivatized using 2-chloroacetaldehyde for fluorescence detection, and the reaction and separation conditions were reinvestigated to improve sensitivity for small volume sample analysis. Each derivatized purine was separated on a Capcell Pack SG120A column with mobile phase consisting of 0.05 M citric acid-0.1 M dipotassium hydrogen phosphate (pH 4.0)-methanol (97+3). The detection limits were 100-1000 fmol/ml by fluorescence detection, some 500 times better than previous reports. The proposed method was applied to determine adenyl purines in human plasma. The purine levels were as follows: ATP (9.2-22.2 pmol/ml), ADP (5.5-22.2 pmol/ml), AMP (0.8-3.2 pmol/ml). Other purines, adenine, adenosine, cAMP were lower than 0.1 pmol/ml.

Calibration↗