Biomedical subjects

T Ishikawa

Publications and source records attributed to T Ishikawa.

At least 19 recordsLinked to original sources

PubMed2007

Expression of leptin and leptin receptor in the testis of fertile and infertile patients.

The aim of our study was to investigate the relationships between the expression of leptin, leptin receptor in the testis and spermatogenesis, and testosterone (T) concentration in infertile men. Testicular tissue samples were collected from the testes of five fertile volunteers, eight patients with obstructive azoospermia (OA), six patients with Sertoli cell-only syndrome (SCO) and 32 oligospermic patients with varicocele testis. In testicular tissue, leptin and leptin receptor were identified by staining with polyclonal antibodies. Serum follicle stimulating hormone, lutenising hormone (LH), and T were determined by chemiluminescence assays. Leptin was expressed on germ cells, mainly on spermatocytes. The ratio of immunostained germ cells to total germ cells was inversely correlated with the concentration of T (r = -0.32, P = 0.01), sperm concentration (r = -0.51, P = 0.002) and Johnsen's score (r = -0.44,P = 0.005). In contrast, leptin receptor immunostained cells were found in the interstitium, primarily in Leydig cells. Leptin receptor expression on Leydig cells was inversely correlated with serum T concentration (r = -0.50, P < 0.001). The dysfunction of spermatogenesis is associated with an increase in leptin and leptin receptor expression in the testis.

Adult↗

PubMed2006

Transcription-reverse transcription concerted reaction and minimal residual disease in axillary sentinel nodes of breast cancer.

AIMS: To investigate the use of transcription-reverse transcription concerted reaction (TRC) to detect axillary lymph node metastases. METHODS: Metastases in 423 lymph nodes obtained from 50 breast cancer patients were investigated by routine pathological hematoxylin and eosin (H and E) staining and quantitative analysis of carcinoembryonic antigen (CEA) mRNA by TRC. Enhanced pathological studies, serial sectioning and immunohistochemistry were conducted for cases which were negative by routine pathology, but positive by TRC. RESULTS: Pathological examination identified metastatic disease in 67 lymph nodes. TRC CEA mRNA results were concordant with 89.8% of these cases at a threshold of 100 copies. TRC identified 30 false negative nodes, which was reduced to 15 by excluding node biopsies yielding less than 40 microg total RNA. Twelve nodes were histologically negative for cancer, but positive according to TRC. Serial sectioning and immunohistochemical analysis of these nodes revealed macrometastatic lesions in three, micrometastasis in one, and isolated tumor cells in two. CONCLUSION: TRC for the detection of CEA mRNA may complement routine pathological examination by sentinel lymph node biopsy (SNB) in early breast cancer. We have started an enhanced pathological examination with serial sectioning on all excised sentinel nodes to set the best threshold for the TRC method.

Adult↗

PubMed2006

Isolation and characterization of sex chromosome rearrangements generating male muscle dystrophy and female abnormal oogenesis in the silkworm, Bombyx mori.

In deletion-mapping of W-specific RAPD (W-RAPD) markers and putative female determinant gene (Fem), we used X-ray irradiation to break the translocation-carrying W chromosome (W( Ze )). We succeeded in obtaining a fragment of the W( Ze ) chromosome designated as Ze (W), having 3 of 12 W-RAPD markers (W-Bonsai, W-Yukemuri-S, W-Yukemuri-L). Inheritance of the Ze (W) fragment by males indicates that it does not include the Fem gene. On the basis of these results, we determined the relative positions of W-Yukemuri-S and W-Yukemuri-L, and we narrowed down the region where Fem gene is located. In addition to the Ze (W) fragment, the Z chromosome was also broken into a large fragment (Z(1)) having the +( sch ) (1-21.5) and a small fragment (Z(2)) having the +( od ) (1-49.6). Moreover, a new chromosomal fragment (Ze (W)Z(2)) was generated by a fusion event between the Ze (W) and the Z(2) fragments. We analyzed the genetic behavior of the Z(1) fragment and the Ze (W)Z(2) fragment during male (Z/Z(1) Ze (W)Z(2)) and female (Z(1) Ze (W)Z(2)/W) meiosis using phenotypic markers. It was observed that the Z(1) fragment and the Z or the W chromosomes separate without fail. On the other hand, non-disjunction between the Ze (W)Z(2) fragment and the Z chromosome and also between the Ze (W)Z(2) fragment and the W chromosome occurred. Furthermore, the females (2A: Z/Ze (W)Z(2)/W) and males (2A: Z/Z(1)) resulting from non-disjunction between the Ze (W)Z(2) fragment and the W chromosome had phenotypic defects: namely, females exhibited abnormal oogenesis and males were flapless due to abnormal indirect flight muscle structure. These results suggest that Z(2) region of the Z chromosome contains dose-sensitive gene(s), which are involved in oogenesis and indirect flight muscle development.

Animals↗

PubMed2006

Differential cross section and photon-beam asymmetry for the gamma n --> K+ Sigma- reaction at E gamma = 1.5-2.4 GeV.

Differential cross sections and photon-beam asymmetries have been measured for the gamma n --> K+ Sigma- and gamma p --> K+Sigma0 reactions separately using liquid deuterium and hydrogen targets with incident linearly polarized photon beams of E gamma = 1.5-2.4 GeV at 0.6 < cos ThetacmK< 1. The cross section ratio of sigma K+ Sigma-/sigma K+ Sigma0, expected to be 2 on the basis of the isospin 1/2 exchange, is found to be close to 1. For the K+ Sigma- reaction, large positive asymmetries are observed, indicating the dominance of K* exchange. The large difference between the asymmetries for the K+ Sigma- and K+ Sigma0 reactions cannot be explained by simple theoretical considerations based on Regge model calculations.

Journal Article↗

PubMed2006

Identification of arginase in human placental villi.

l-Arginine is the common substrate for arginase and nitric oxide synthase (NOS). Arginase converts l-arginine to urea and ornithine, which is the principal precursor for production of polyamines required for cell proliferation. Human placenta expresses endothelial NOS (eNOS) in syncytiotrophoblasts, but the expression of arginase has not been fully elucidated. Our aim was to investigate the expression and distribution patterns of arginase-I (A-I) and arginase-II (A-II) in human placental villi in the first trimester and at term using immunohistochemistry, RT-PCR and Western blot analysis. The arginase enzyme activity in placental villi was also measured. Immunohistochemistry showed different distribution patterns of the arginase isoforms during gestation: A-I was observed only in cytotrophoblasts, while A-II was observed in both cytotrophoblasts and syncytiotrophoblasts. RT-PCR and Western blot analysis showed expression of A-I and A-II in the first trimester and at term in human placental villi. Expression of A-II and arginase activity was greater in the first trimester than at term. Differentiation of cytotrophoblasts into syncytiotrophoblasts may be associated with l-arginine metabolism through modulation of l-arginine availability for eNOS and A-I. And elevated arginase activity in the early gestational period may be responsible for proliferation of trophoblasts by increasing polyamines production. These results suggest that the l-arginine-ornithine-polyamine and l-arginine-nitric oxide pathways play a role in placental growth and development.

Arginase↗

PubMed2006

Effects of 24R,25- and 1alpha,25-dihydroxyvitamin D3 on mineralizing growth plate chondrocytes.

Time- and dosage-dependent effects of 1,25(OH)(2)D(3) and 24,25(OH)(2)D(3) on primary cultures of pre- and post-confluent avian growth plate (GP) chondrocytes were examined. Cultures were grown in either a serum-containing culture medium designed to closely mimic normal GP extracellular fluid (DATP5) or a commercially available serum-free media (HL-1) frequently used for studying skeletal cells. Hoechst DNA, Lowry protein, proteoglycan (PG), lactate dehydrogenase (LDH), and alkaline phosphatase (ALP) activity and calcium and phosphate mineral deposition in the extracellular matrix were measured. In preconfluent cultures grown in DATP5, physiological levels of 24,25(OH)(2)D(3) (0.10-10 nM) increased DNA, protein, and LDH activity significantly more than did 1,25(OH)(2)D(3) (0.01-1.0 nM). However, in HL-1, the reverse was true. Determining ratios of LDH and PG to DNA, protein, and each other, revealed that 1,25(OH)(2)D(3) specifically increased PG, whereas 24,25(OH)(2)D(3) increased LDH. Post-confluent cells were generally less responsive, especially to 24,25(OH)(2)D(3). The positive anabolic effects of 24,25(OH)(2)D(3) required serum-containing GP-fluid-like culture medium. In contrast, effects of 1,25(OH)(2)D(3) were most apparent in serum-free medium, but were still significant in serum-containing media. Administered to preconfluent cells in DATP5, 1,25(OH)(2)D(3) caused rapid, powerful, dosage-dependent inhibition of Ca(2+) and Pi deposition. The lowest level tested (0.01 nM) caused >70% inhibition during the initial stages of mineral deposition; higher levels of 1,25(OH)(2)D(3) caused progressively more profound and persistent reductions. In contrast, 24,25(OH)(2)D(3) increased mineral deposition 20-50%; it required >1 week, but the effects were specific, persistent, and largely dosage-independent. From a physiological perspective, these effects can be explained as follows: 1,25(OH)(2)D(3) levels rise in hypocalcemia; it stimulates gut absorption and releases Ca(2+) from bone to correct this deficiency. We now show that 1,25(OH)(2)D(3) also conserves Ca(2+) by inhibiting mineralization. The slow anabolic effects of 24,25(OH)(2)D(3)are consistent with its production under eucalcemic conditions which enable bone formation. These findings, which implicate serum-binding proteins and accumulation of PG in modulating accessibility of the metabolites to GP chondrocytes, also help explain some discrepancies previously reported in the literature.

24,25-Dihydroxyvitamin D 3↗

PubMed2006

X-ray diffractometer combining synchrotron radiation and pulsed magnetic fields up to 40 T.

A synchrotron X-ray diffractometer incorporating a pulsed field magnet for high fields up to 40 T has been developed and a detailed description of this instrument is reported. The pulsed field magnet is composed of two coaxial coils with a gap of 3 mm at the mid-plane for passage of the X-rays. The pixel detector PILATUS 100K is used to store the diffracted X-rays. As a test of this instrument, X-ray diffraction by a powder sample of the antiferromagnet CoO is measured below the Néel temperature. A field-dependent lattice distortion of CoO due to magnetostriction is observed up to 38 T.

Journal Article↗

PubMed2006

Endothelial expression of Fc gamma receptor IIb in the full-term human placenta.

In the third trimester, human placental endothelial cells express Fc gamma receptor IIb (FcgammaRIIb). This expression is unique because FcgammaRIIb is generally expressed on immune cells and is typically undetectable in adult endothelial cells. Recently, we found a novel FcgammaRIIb-defined, IgG-containing organelle in placental endothelial cells; this organelle may be a key structure for the transcytosis of IgG across the endothelial layer. In this study, we verify the expression of FcgammaRIIb in endothelial placenta cells and use reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing analyses to define the expressed FCGR2B mRNA transcript variant. We also investigated the distribution of FCGR2B mRNA and protein within the vascular tree of the full-term human placenta by RT-PCR and quantitative microscopy. The mRNA sequence of FCGR2B expressed specifically in placental endothelial cells is that of transcript variant 2. FcgammaRIIb expression and synthesis occur throughout the placental vascular tree but do not extend into the umbilical cord. This study provides additional information on FcgammaRIIb expression in the human placenta.

Endothelial Cells↗

PubMed2006

Clinical significance of circulating hepatocyte growth factor, a new risk marker of carotid atherosclerosis in patients with Type 2 diabetes.

AIMS: Recent studies have provided increasing evidence that hepatocyte growth factor (HGF) has a pathophysiological role in the development of diabetic complications. We set out to determine the relationship between serum HGF and risk factors for macroangiopathy including carotid atherosclerosis. Carotid atherosclerosis is an established and important risk factor for both cerebral and coronary artery diseases. METHODS: We studied 89 patients (48 males, 41 females, mean age 62.5 +/- 10.3 years) with Type 2 diabetes (DM). RESULTS: Serum levels of HGF correlated positively with both intimal-media thickness (IMT) (r = 0.24, P = 0.0248) and plaque score (r = 0.27, P = 0.0126). In multiple regression analysis, serum HGF was associated independently with IMT (standardized beta = 0.28, P = 0.0499). We also found that both IMT and plaque score were higher in patients with ischaemic heart disease (IHD) than in patients without IHD, and that plaque score in patients with lacunar infarcts was higher than in patients without lacunar infarcts. CONCLUSIONS: Serum HGF concentration may be a new marker of atherosclerotic complications in patients with Type 2 DM.

Age Factors↗

PubMed2006

Effects of therapeutic agents on cellular respiration as an indication of metabolic activity.

Animal experiments are indispensable in the investigation of the toxicity of drugs on cells, but may not be preferred for ethical reasons and sensitivity. As an alternative procedure, we investigated the susceptibility of cells to drugs using the effect on cellular respiration as an indicator of cell activity (toxicity). The primary cultures (cell lines) used in this study included human fetal myocardial cells, skeletal muscle cells, nerve cells, hypophyseal cells, epithelial cells of gastric mucosa, lymphocytes, hepatocytes, pancreatic (exocrine) cells, renal tubular epithelial cells and fetal adrenal cortex cells, which were obtained from the American Type Culture Collection (ATCC). The drugs used were diazepam, haloperidol and levomepromazine maleate (psychoactive drugs), cisplatin and doxorubicin hydrochloride (anticancer agents). The cells were used at a density of 2 x 10(6) cells/2 mL of growth medium and, to test the susceptibility, each drug was prepared at a concentration of 10 g/mL. Experiment results indicated that, even with the same drug, sensitivity was markedly different depending on the cell lines. Cardiac muscle cells showed the strongest respiratory inhibition by Serenace and were least inhibited by Hirnamin. The highest sensitivity to Cercine was noted for neurons, while gastric mucosa cells had almost no sensitivity. Sensitivity to Serenace, which was expected to have a strong nerve action, was higher in myocardial cells instead. In the present study, we suggested the possibility of studying individual differences in drug sensitivity through investigation of toxicity in each organ as opposed to toxicity in the individual. In addition, Serenace, which was developed as a neurotopic agent, showed a higher toxicity in cardiac muscle cells than in neurons. This finding appeared noteworthy, not only for forensic toxicology, but also for clinical practice and drug development.

Cell Count↗

PubMed2005

Performance of a whole-body counter with five high-purity germanium detectors.

A germanium (Ge) detector system has been installed in a whole-body counting facility at NIRS (Japan). The system employs five detectors that have relative efficiencies of more than 80%. A basic performance of the Ge detectors was tested and compared with that of the former NaI(Tl) detector system. Although the Ge detector system has advantages of improved radionuclide identification capability and MDA values, it also has disadvantages of high operation costs and demanding maintenance such as supply of liquid nitrogen.

Body Burden↗

PubMed2005

Near-threshold diffractive psi-meson photoproduction from the proton.

Photoproduction of a phi meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to Egamma = 2.37 GeV. The differential cross sections at t = -|t|min do not increase smoothly as Egamma increases but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that phi mesons are photoproduced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes.

Journal Article↗

PubMed2005

Evidence for suppressed screening on the surface of high temperature La(2-x)SrxCuO4 and Nd2(2-x)CexCuO4 superconductors.

Hard x-ray photoemission spectroscopy (PES) of Cu core electronic states, with a probing depth of approximately 60 A, is used to show that the Zhang-Rice singlet feature is present in La2CuO4 but is absent in Nd2CuO4. Hole and electron doping in La(2-x)SrxCuO4 (LSCO) and Nd(2-x)CexCuO4 (NCCO) result in new well-screened features which are missing in soft x-ray PES. Impurity Anderson model calculations establish screening from doped states as its origin, which is strongly suppressed within 15 A of the surface. Complemented with x-ray absorption spectroscopy, the small chemical-potential shift in core levels (approximately 0.2 eV) are shown to be consistent with modifications of valence and conduction band states spanning the band gap (approximately 1 eV) upon hole and electron doping in LSCO and NCCO.

Journal Article↗

PubMed2005

The transcriptional landscape of the mammalian genome.

This study describes comprehensive polling of transcription start and termination sites and analysis of previously unidentified full-length complementary DNAs derived from the mouse genome. We identify the 5' and 3' boundaries of 181,047 transcripts with extensive variation in transcripts arising from alternative promoter usage, splicing, and polyadenylation. There are 16,247 new mouse protein-coding transcripts, including 5154 encoding previously unidentified proteins. Genomic mapping of the transcriptome reveals transcriptional forests, with overlapping transcription on both strands, separated by deserts in which few transcripts are observed. The data provide a comprehensive platform for the comparative analysis of mammalian transcriptional regulation in differentiation and development.

3' Untranslated Regions↗

PubMed2005

Blue-dye technique complements four-node sampling for early breast cancer.

AIMS: To examine four-node axillary sampling assisted by a blue dye (4NAS/dye) technique as a sentinel node biopsy (SNB) for breast cancer. METHODS: Lymphatic mapping was performed by injection of patent blue for 33 consecutive cases with breast cancer. Axillary sampling was performed until four nodes were obtained. This was followed by back-up axillary lymph node dissection to examine the feasibility of 4NAS/dye. The same study with 30 cases was conducted at an independent hospital to confirm the feasibility of this method. This method was then applied to 101 consecutive clinically node-negative patients to avoid axillary-node dissection, with intraoperative diagnosis made by frozen section examination. RESULTS: The median numbers of blue-stained nodes and nodes excised by 4NAS/dye were 1.7 and 3.4, respectively. The identification rate of sentinel lymph nodes (SNs) was 81.8% using the dye alone and 97.0% when the combination was used. Pathological examination revealed that the nodal status was correctly predicted by the dye alone in 62.5% of cases with metastasis, whereas in 100% by 4NAS/dye. The dye alone was not sufficient to identify SNs, especially in cases with prior excisional biopsy. The identification rate of SNs and the accuracy rate in another feasibility study were 100% and 92.5% in 30 consecutive cases, respectively. 4NAS/dye successfully detected SNs in 100 of 101 cases of the subsequent observational study with an acceptable post-operative axillary morbidity and thus succeeded as an SNB. CONCLUSIONS: The 4NAS/dye method is reliable for the detection of SNs. This method could be applied to observational studies without radio-isotope.

Adult↗

PubMed2005

X-ray resonance in crystal cavities: realization of Fabry-Perot resonator for hard x rays.

X-ray back diffraction from monolithic two silicon crystal plates of 25-150 microm thickness and a 40-150 microm gap using synchrotron radiation of energy resolution DeltaE = 0.36 meV at 14.4388 keV clearly show resonance fringes inside the energy gap and the total-reflection range for the (12 4 0) reflection. This cavity resonance results from the coherent interaction between the x-ray wave fields generated by the two plates with a gap smaller than the x-ray coherence length. This finding opens up new opportunities for high-resolution and phase-contrast x-ray studies, and may lead to new developments in x-ray optics.

Journal Article↗

PubMed2005

Efficacy of epidermal growth factor receptor-targeted molecular therapy in anaplastic thyroid cancer cell lines.

Anaplastic thyroid cancer is one of the most aggressive human malignancies and the outcomes of conventional therapy have been far from satisfactory. Recently, epidermal growth factor receptor (EGFR)-targeted therapy has been introduced as an alternative therapeutic strategy for highly malignant cancers. This study was undertaken to investigate the expression of EGFR in anaplastic thyroid cancer cell lines, and to explore the potential of therapies targeting EGFR as a new therapeutic approach. EGFR was universally expressed in anaplastic cancer cell lines at a variety of levels. Specific EGFR stimulation with epidermal growth factor showed significant phosphorylation of ERK1/2 and Akt, and resulted in marked growth stimulation in an anaplastic thyroid cancer cell line, which highly expressed EGFR. This EGFR-transmitted proliferation effect of the cancer cell line was completely inhibited by gefitinib, an EGFR tyrosine kinase inhibitor. Moreover, growth of xenografts inoculated in mice was inhibited in a dose-dependent manner with 25-50 mg kg(-1) of gefitinib administrated orally. Inhibition of EGFR-transmitted growth stimulation by gefitinib was clearly observed in anaplastic thyroid cancer cell lines. Our results suggested that EGFR-targeted therapy, such as gefitinib, might be worth further investigation for the treatment of anaplastic thyroid cancer.

Animals↗

PubMed2005

Study on adsorption mechanism of proteins onto synthetic calcium hydroxyapatites through ionic concentration measurements.

To clarify the adsorption mechanism of proteins onto calcium hydroxyapatite (Hap), the kinetic studies of dissolution and ion-exchange properties of synthetic Hap particles in the absence and presence of proteins were examined at 15 degrees C. In the absence of proteins, Hap particles slightly dissolved to give low amounts of calcium ([Ca(2+)] = 0.09-0.14 micromol m(-2)) and phosphate [PO(4) (3-)] = 0.01-0.08 micromol m(-2)) ions in KCl, CaCl(2), BaCl(2) and AlCl(3) solutions. The [Ca(2+)] increased with increase in the Ca/P ratio of Hap, while the [PO(4) (3-)] decreased. The[ Ca(2+)] and [ PO(4) (3-)] were independent of the ionic strength. Ba(2+) and AI(3+) ions were completely ion-exchanged with calcium ions in Hap lattice within 2 hr. The solution pH was increased by 1.1-1.8 after the dissolution of OH(-) ions on the Hap surface. In the presence of bovine serum albumin (BSA), the Hap particles dissolved slightly faster than the systems without protein. This fact was explained by a complexation of dissolved ions to functional groups of BSA. The adsorption of BSA induced a reduction of [Ca(2+)] and [ PO(4) (3-)] in the aqueous medium and minima appeared on [Ca(2+)] and [PO(4) (3-)] profiles before the BSA adsorption reached a saturation. This result suggests that the adsorption of BSA onto Hap is governed by [Ca(2+)] ions complexing to BSA molecules (binding effect) together with the operation of [Ca(2+)] ions exposing on the Hap surfaces by dissolution of OH(-) ions, so-called "C-sites". The addition of BaCl(2) and AlCl(3 )steeply increased the amounts of adsorbed BSA (n(BSA)) at the initial adsorption step by the strong binding effect of these di- and tri-valent cations between BSA and Hap. However, after eliminating these cations from the Hap surface by the ion-exchange reaction, the binding effects disappeared and n(BSA) decreased. Since the number of functional groups is small, the binding effect of the counter ions was only slightly detected for the systems with di- and trivalent ions on the adsorption systems of lysozyme (LSZ).

Adsorption↗