Biomedical subjects

T Yamagata

Publications and source records attributed to T Yamagata.

At least 55 records · Page 3Linked to original sources

PubMed2000

Possible role of hepatocyte growth factor/scatter factor and activin A produced by the target organ in liver metastasis.

The molecular mechanism of organ-specific metastasis to the liver remains largely unknown. However, it is conceivable that paracrine growth factors produced by a target organ induce migration and proliferation of malignant cells to that organ, and this is the cause of organ-specific metastasis. In this study, we investigated the effect of hepatocyte growth factor/scatter factor (HGF/SF) and activin A, which are known to be produced by the liver, on the motility and growth of liver-metastatic cell line FBJ-LL. HGF/SF and activin A induced motility synergistically, but they did not affect the proliferation of FBJ-LL cells. Expression of the HGF/SF receptor, the c-met gene, and the activin-receptor type IA, type IB, and type IIA genes in FBJ-LL cells was detected by reverse transcription polymerase chain reaction. These findings suggest that both HGF/SF and activin A promote organ-specific metastasis to the liver by induction of migration through their specific receptors on liver-metastatic cells.

Activin Receptors, Type I↗

PubMed2000

Genomic rearrangement in NEMO impairs NF-kappaB activation and is a cause of incontinentia pigmenti. The International Incontinentia Pigmenti (IP) Consortium.

Familial incontinentia pigmenti (IP; MIM 308310) is a genodermatosis that segregates as an X-linked dominant disorder and is usually lethal prenatally in males. In affected females it causes highly variable abnormalities of the skin, hair, nails, teeth, eyes and central nervous system. The prominent skin signs occur in four classic cutaneous stages: perinatal inflammatory vesicles, verrucous patches, a distinctive pattern of hyperpigmentation and dermal scarring. Cells expressing the mutated X chromosome are eliminated selectively around the time of birth, so females with IP exhibit extremely skewed X-inactivation. The reasons for cell death in females and in utero lethality in males are unknown. The locus for IP has been linked genetically to the factor VIII gene in Xq28 (ref. 3). The gene for NEMO (NF-kappaB essential modulator)/IKKgamma (IkappaB kinase-gamma) has been mapped to a position 200 kilobases proximal to the factor VIII locus. NEMO is required for the activation of the transcription factor NF-kappaB and is therefore central to many immune, inflammatory and apoptotic pathways. Here we show that most cases of IP are due to mutations of this locus and that a new genomic rearrangement accounts for 80% of new mutations. As a consequence, NF-kappaB activation is defective in IP cells.

Exons↗

PubMed2000

Large expansion of the ATTCT pentanucleotide repeat in spinocerebellar ataxia type 10.

Spinocerebellar ataxia type 10 (SCA10; MIM 603516; refs 1,2) is an autosomal dominant disorder characterized by cerebellar ataxia and seizures. The gene SCA10 maps to a 3.8-cM interval on human chromosome 22q13-qter (refs 1,2). Because several other SCA subtypes show trinucleotide repeat expansions, we examined microsatellites in this region. We found an expansion of a pentanucleotide (ATTCT) repeat in intron 9 of SCA10 in all patients in five Mexican SCA10 families. There was an inverse correlation between the expansion size, up to 22.5 kb larger than the normal allele, and the age of onset (r2=0.34, P=0.018). Analysis of 562 chromosomes from unaffected individuals of various ethnic origins (including 242 chromosomes from Mexican persons) showed a range of 10 to 22 ATTCT repeats with no evidence of expansions. Our data indicate that the new SCA10 intronic ATTCT pentanucleotide repeat in SCA10 patients is unstable and represents the largest microsatellite expansion found so far in the human genome.

Animals↗

PubMed2000

Double ventricular response by a single ventricular extrastimulus to the inner loop of reentry in a patient without apparent heart disease.

In a patient without apparent heart disease, a ventricular extrastimulus delivered from the left ventricular apex where the electrogram was recorded 30 ms after the onset of the QRS complex during VT advanced the second QRS complex, but not the first QRS complex. The morphology of the second QRS complex was the same as that of VT. The postpacing interval was the same as the cycle length of the VT. These findings indicated that the site of stimulation was at the inner loop of the reentry circuit of the VT. A ventricular extrastimulus with a shorter coupling interval advanced the first and second QRS complexes, indicating that the ventricle was activated by antidromic and orthodromic activation from the extrastimulus. Radiofrequency ablation at that site of stimulation terminated the VT and no further VT could be induced.

Aged↗

PubMed2000

Scanning electron microscopic study of the neuromuscular junctions of the cricothyroid and thyroarytenoid muscles in rats.

Neuromuscular junctions were observed in the cricothyroid (CT) and thyroarytenoid (TA) muscles of adult rats by scanning electron microscopy after removing the intramuscular connective tissue components using the HCI hydrolysis method. Morphologically, the junctions were classified into three types in the CT muscle and two types in the TA muscle, based on the structural characteristics of the subneural apparatuses, including junctional folds. In the CT muscle, type 1 junctions (32%) consisted of more than 15 cup-like depressions with slit-like junctional folds. Type 2 junctions (20%) were characterized by approximately 10 cup-like depressions with a small number of pit- or slit-like junctional folds. Type 3 junctions (48%) had irregular labyrinthine gutters with slit-like junctional folds. In the TA muscle, type 1 (82%) and 2 (18%) junctions had similar structures to type 1 and 2 junctions in the CT muscle, respectively. Histochemical studies using myosin adenosine triphosphatase staining showed that both CT and TA muscles predominantly consisted of type II muscle fibers (78% and 82%, respectively), and that the diameter of type II fibers was larger than that of type I fibers. These findings suggest that the type 2 junction belongs to type I muscle fibers, while both type 1 and type 3 junctions belong to type II fibers, and that the type 3 junction is a structural variation of the type 1 junction. The significance of the structural differences of the subneural apparatuses in the intrinsic laryngeal muscles is discussed briefly.

Animals↗

PubMed2000

Hereditary persistent right oviduct in the chicken PNP/DO line.

Hereditary, persistent, right oviduct manifested in an inbred line (PNP/DO line) from the Fayoumi breed of chickens was investigated for form of expression and mode of inheritance. Females in the PNP/DO line have varying lengths of elongated right oviducts, besides the normal left ovary, and oviducts that generally possess, irrespective of their total length, regions similar to those normally observed in a left oviduct. Observations of embryos indicated that the existence of right oviduct in this line could be attributed to the slow regression of right Müllerian duct during the embryonic stage, and left-right asymmetry in female genital system is intrinsic in this line. Intracrosses of the PNP/DO line produced 93% of female embryos with persistent right Müllerian ducts at the next generation, and reciprocal crosses of the PNP/DO line and control strains produced 5 and 30% of female embryos with persistent right Müllerian ducts in the F1 and N2 generations, respectively. Mating results suggested that this mutant trait is controlled by two pairs of autosomal recessive genes with major effects and numerous loci that have minor effects. Thus, expression of this trait is due to the interaction of major loci and the background genotype.

Animals↗

PubMed2000

A Robertsonian translocation, rob(2;28), found in Vietnamese cattle.

A new Robertsonian translocation, rob(2;28), was discovered in a local population of the Vietnamese Cattle. The animal (2n = 59, XY) was found by Q- and R-banding to be a heterozygous carrier of a centric fusion translocation involving chromosomes 2 and 28. FISH analysis using a bovine satellite I DNA probe demonstrated that the centromeric heterochromatin block of the rob(2;28) chromosome become much smaller than its ancestors suggesting a monocentric nature of this centric fusion. This is the first report identifying a Robertsonian translocation in Southeast Asian cattle by karyotyping of banded chromosomes.

Animals↗

PubMed2000

CIZ, a zinc finger protein that interacts with p130(cas) and activates the expression of matrix metalloproteinases.

p130(cas) (Cas) is a docking protein that contains an SH3 domain and multiple tyrosine residues. p130(cas) is located at focal adhesions, is tyrosine phosphorylated in response to integrin stimulation, and is thought to transmit signals, via c-Crk and other proteins, for the remodeling of actin stress fibers and cell movement. In a search for the ligands of the SH3 domain of p130(cas) by far-Western screening, we cloned a novel protein named CIZ (for Cas-interacting zinc finger protein). CIZ consists of the following: a putative leucine zipper; a serine/threonine-rich region; a proline-rich sequence; five, six, or eight Krüppel-type C(2)H(2) zinc fingers; and the glutamine-alanine repeat. CIZ binds Cas in cells and is located in the nucleus and at focal adhesions. We showed that CIZ is a nucleocytoplasmic shuttling protein, by using the transient interspecies heterokaryon formation assay. In order to search for the targets of CIZ in nucleus, we determined the DNA binding consensus of CIZ as (G/C)AAAAA(A) by cyclic amplification and selection of targets analysis. The consensus-like sequences are found in several promoters of matrix metalloproteinases (MMPs), which are the enzymes used to degrade the extracellular matrix proteins. CIZ binds to a consensus-like sequence in the MMP-1 (collagenase) promoter. Overexpression of CIZ upregulates the transcriptions from MMP-1, MMP-3 (stromelysin), and MMP-7 (matrilysin) promoters, and this transactivation was enhanced in the presence of Cas. Furthermore, the stable overexpression of CIZ promoted the production of MMP-7 in culture medium. In summary, CIZ, a novel zinc finger protein, binds Cas, is a nucleocytoplasmic shuttling protein, and regulates the expression of MMPs.

Amino Acid Sequence↗

PubMed2000

The preventive effect of magnesium on coronary spasm in patients with vasospastic angina.

STUDY OBJECTIVES: Previous studies have reported that magnesium (Mg) deficiency is associated with coronary spasm. However, little is known about the preventive effect of Mg on coronary spasm. The present study investigated whether Mg prevents coronary spasm in patients with vasospastic angina (VSA). DESIGN: Effectiveness trial. SETTING: University medical center. PATIENTS: Twenty-two patients with VSA. INTERVENTION: Coronary spasm was induced with an intracoronary infusion of acetylcholine (Ach). After spontaneous relief of the coronary spasm, Mg sulfate (0.27 mmol/kg body weight) was infused IV over 20 min in 14 patients and isotonic glucose was infused in 8 patients as control subjects. Intracoronary infusion of Ach was then repeated, and the diameter of the coronary arteries was measured quantitatively. MEASUREMENTS AND RESULTS: Mg infusion caused coronary artery dilatation at baseline in both the spastic (5. 9 +/- 2.3%) and nonspastic segments (5.5 +/- 1.5%). Mg infusion reduced the severity of chest pain and ST-segment deviations during coronary spasm. After the Mg infusion, the percent change in the diameter of the spastic segments improved from - 62.8 +/- 2.6% to - 43.7 +/- 4.7% during coronary spasm. Overall, 10 of 14 patients (71%) responded favorably to Mg infusion. Isotonic glucose infusion did not elicit changes in chest pain severity, ST-segment deviations, or the diameter of the coronary arteries during spasm. CONCLUSIONS: Mg infusion produces nonsite-specific basal coronary dilatation and suppresses Ach-induced coronary spasm in patients with VSA.

Acetylcholine↗

PubMed2000

Postnatal morphodifferentiation of the subneural apparatuses of the posterior cricoarytenoid muscle in rats: a scanning electron microscopy study.

The subneural apparatus, i. e., the post-synaptic component of the neuromuscular junction, in the posterior cricoarytenoid muscle of the rat was studied by scanning electron microscopy, with special attention given to its postnatal differentiation along with the functional development of the muscle. Primitive synaptic troughs observed in the first postnatal week consisted of single cup-like depressions 5-6 microm in diameter. On the 7th day, low sarcoplasmic ridges appeared in the trough. In the second postnatal week, muscle fibers could be classified into two groups: large (10-15 microm in diameter) and small (less than 10 microm in diameter). In the large muscle fibers, many low ridges became circular and protruded to transform the single trough into numerous cup-like depressions (2-5 microm in diameter). In contrast, the subneural apparatus in the small muscle fibers consisted of a small number of cup-like depressions. The two types of subneural apparatus differentiated into adult forms by the 28th postnatal day, although they remained smaller in size than those of adults. In the large muscle fibers, the number of pit-like or elongated invaginations increased and gradually transformed into slit-like junctional folds by the 28th postnatal day, while the small muscle fibers still possessed a few pit-like or elongated junctional folds at this point in time. The two types of morphodifferentiation of the subneural apparatus are thought to reflect the two types of muscle fibers in the rat posterior cricoarytenoid muscle.

Age Factors↗

PubMed2000

Comparison of properties of slow pathway potential between successful and unsuccessful radiofrequency applications in patients who underwent catheter ablation for atrioventricular nodal reentrant tachycardia.

Findings concerning selective slow pathway radiofrequency ablation for atrioventricular nodal reentrant tachycardia (AVNRT) using the slow pathway potential (SPP) guided method are reported. The electrogram at the SPP recording site showed double potentials consisting of the atrial potential (A) and SPP. However, SPP is usually recorded widely in the right atrial posteroseptal region. To examine whether there was any characteristic marker in the electrogram at the SPP recording site specific to successful RF application, the properties of SPP and its anatomical locations in both successful (S) (38 sites) and unsuccessful (UN) (28 sites) application sites were analyzed in 38 patients who underwent SPP-guided ablation. The distance between the upper margin of the coronary sinus ostium (UCSO) and the ablation catheter (ABL) (DUCSO-ABL) was shorter in S than in UN (2.3 +/- 6.3 mm vs. 9.0 +/- 5.2 mm below the level of UCSO, p < 0.001). The interval between A and SPP (A-SPP) was longer in S than in UN (44.2 +/- 9.9 msec vs. 24.0 +/- 7.0 msec, p < 0.001). RF applications at the more anterior sites with longer A-SPP were more successful than at other sites. The sensitivity and specificity of A-SPP (more than 40 msec) were superior to those of DUCSO-ABL (within 5 mm) as the marker for the successful application (sensitivity; 73.7% v.s. 68.4%, specificity; 100% v.s. 82.1%, respectively). In conclusion, the sites with longer A-SPP might be specific for successful ablation.

Adolescent↗

PubMed2000

[A case of pulmonary cavernous hemangioma: immunohistological examination revealed its endothelial cell origin].

A 29-year-old woman was referred to our hospital for an abnormal shadow on chest roentgenogram. She had no symptom but its shadow was pointed out about 20 years ago. Chest CT scan showed a sharply demarcated homogenous mass measured 10 x 10 mm in the S4 segment. The tumor was resected with video-assisted thoracoscopic surgery under CT-guided marking wire inserted. Microscopic examination suspected cavernous hemangioma. Immunohistological staining demonstrated most lining cells of the cavernous structure stained positively for von Willebrand factor antibody, which suggests that this tumor was associated with endothelium. Then we decided that this tumor was pulmonary cavernous hemangioma.

Adult↗

PubMed1999

Suppression by ganglioside GD1A of migration capability, adhesion to vitronectin and metastatic potential of highly metastatic FBJ-LL cells.

Ganglioside GD1a, which is highly expressed in poorly metastatic FBJ-S1 cells, has been shown to inhibit the serum-induced migration capability of highly metastatic FBJ-LL cells. In the present study, the capacity of FBJ-S1 cells to adhere to vitronectin was found to be about half that of FBJ-LL cells. Pre-treatment of FBJ-LL cells with GD1a decreased this capacity by 30% that of the control, whereas GM1-pre-treatment caused only a 10% decrease, indicating that GD1a specifically inhibits FBJ-LL cell adhesion to vitronectin. Since FBJ-LL cells contain almost no GD1a, transfectants capable of expressing GD1a to varying degrees were produced in this study by transfection of FBJ-LL cells with GM2/GD2-synthase cDNA. Decrease in the serum-induced migration capacity of these transfectants was accompanied by an increment in GD1a expression. Adhesion of the transfectants to vitronectin decreased by 30% as compared with mock-transfected cells. Within 4 to 5 weeks after GD1a-expressing transfectant and mock-transfected cells were transplanted into mice, metastatic nodules were observed in liver, lung, kidney and adrenal glands of mock-transplanted mice, but not in those with GD1a-expressing transfectants, indicating that GD1a suppresses the metastasis of FBJ-osteosarcoma cells, possibly by inhibiting cell migration and cell adhesion. The involvement of the ganglioside in the suppression of metastasis is clearly demonstrated in the present study.

Animals↗

PubMed1999

Molecular dynamics of MHC genesis unraveled by sequence analysis of the 1,796,938-bp HLA class I region.

The intensely studied MHC has become the paradigm for understanding the architectural evolution of vertebrate multigene families. The 4-Mb human MHC (also known as the HLA complex) encodes genes critically involved in the immune response, graft rejection, and disease susceptibility. Here we report the continuous 1,796,938-bp genomic sequence of the HLA class I region, linking genes between MICB and HLA-F. A total of 127 genes or potentially coding sequences were recognized within the analyzed sequence, establishing a high gene density of one per every 14.1 kb. The identification of 758 microsatellite provides tools for high-resolution mapping of HLA class I-associated disease genes. Most importantly, we establish that the repeated duplication and subsequent diversification of a minimal building block, MIC-HCGIX-3.8-1-P5-HCGIV-HLA class I-HCGII, engendered the present-day MHC. That the currently nonessential HLA-F and MICE genes have acted as progenitors to today's immune-competent HLA-ABC and MICA/B genes provides experimental evidence for evolution by "birth and death," which has general relevance to our understanding of the evolutionary forces driving vertebrate multigene families.

Base Pairing↗

PubMed1999

Identification of three merB genes and characterization of a broad-spectrum mercury resistance module encoded by a class II transposon of Bacillus megaterium strain MB1.

The complete structure of a broad-spectrum mercury resistance module was shown by sequencing the Gram-positive bacterial transposon TnMERI1 of Bacillus megaterium MB1. The regions encoding organomercury resistance were identified. Upstream of a previously identified organomercurial lyase merB (merB1) region of TnMERI1, a second merR (merR2) and a second merB gene (merB2) were found. These genes constitute a second operon (mer operon 2) following a promoter/operator (P(merR2)) region. A third organomercurial lyase gene (merB3) was found immediately upstream of the mer operon (mer operon 1) followed by a promoter/operator (P(merB3)) region homologous to that of the mer operon 1 (P(merR1)-merR1-merE-like-merT-merP-merA). The complete genetic structure of the mercury resistance module is organized as P(merB3)-merB3-P(merR1)-merR1-merE-like-merT+ ++ -merP-merA-P(merR2)-merR2 -merB2-merB1. The subcloning analysis of these three merB genes showed distinct substrate specificity as different organomercury lyase genes.

Amino Acid Sequence↗

PubMed1999

A dipole mode in the tropical Indian Ocean.

For the tropical Pacific and Atlantic oceans, internal modes of variability that lead to climatic oscillations have been recognized, but in the Indian Ocean region a similar ocean-atmosphere interaction causing interannual climate variability has not yet been found. Here we report an analysis of observational data over the past 40 years, showing a dipole mode in the Indian Ocean: a pattern of internal variability with anomalously low sea surface temperatures off Sumatra and high sea surface temperatures in the western Indian Ocean, with accompanying wind and precipitation anomalies. The spatio-temporal links between sea surface temperatures and winds reveal a strong coupling through the precipitation field and ocean dynamics. This air-sea interaction process is unique and inherent in the Indian Ocean, and is shown to be independent of the El Niño/Southern Oscillation. The discovery of this dipole mode that accounts for about 12% of the sea surface temperature variability in the Indian Ocean--and, in its active years, also causes severe rainfall in eastern Africa and droughts in Indonesia--brightens the prospects for a long-term forecast of rainfall anomalies in the affected countries.

Journal Article↗

PubMed1999

Structure analysis of a class II transposon encoding the mercury resistance of the Gram-positive Bacterium bacillus megaterium MB1, a strain isolated from minamata bay, Japan.

A unique transposon was found in the chromosome of Bacillus megaterium MB1, a Gram-positive bacterium isolated from mercury-polluted sediments of Minamata Bay, Japan. The transposon region of a 14.5kb DNA fragment was amplified by PCR using a single PCR primer designed from the nucleotide sequence of an inverted repeat of class II transposons. The molecular analysis revealed that the PCR-amplified DNA fragment encodes a transposition module similar to that of Tn21. The transposon also encodes a broad-spectrum mercury resistance region having a restriction endonuclease map identical to that of Bacillus cereus RC607, a strain isolated from Boston Harbor, USA. The result of a phylogenetic analysis of the amino acid sequence of putative resolvase of the transposon showed that the transposon is phylogenetically closer to the transposons of Gram-positive bacteria than those of Gram-negative bacteria. Besides the transposition module and mer operon, the transposon encodes a mobile genetic element of bacterial group II introns between the resolvase gene and mer operon. The intron, however, does not intervene in any exon gene. The discovery of this newly found combination of the complex mobile elements may offer a clue to understanding the horizontal dissemination of broad-spectrum mercury resistance among microbes.

Bacillus megaterium↗

PubMed1999

ICSAT overexpression is not sufficient to cause adult T-cell leukemia or multiple myeloma.

ICSAT (Interferon Consensus Sequence binding protein for Activated T cells) is a lymphocyte-specific member of the interferon regulatory factor (IRF) family of transcription factors, originally identified through Southwestern screening of the ATL(Adult T-cell leukemia)-16T expression library. In this study, we created transgenic mice overexpressing ICSAT in lymphocytes. Although spontaneous tumorigenesis was not observed, IL-2 production with Concanavalin A stimulation was significantly increased in transgenic mice overexpressing ICSAT. ICSAT overexpression in lymphocytes seems insufficient for the leukemogenesis of ATL or multiple myeloma (MM), however, it may regulate T cell activation and its overexpression may lead to leukemogenesis via controlling IL-2 production.

Adult↗