Biomedical subjects

K Izawa

Publications and source records attributed to K Izawa.

At least 19 recordsLinked to original sources

PubMed2006

Premedication with cyclooxygenase-2 inhibitor meloxicam reduced postoperative pain in patients after oral surgery.

The efficacy of the selective cyclooxygenase-2 (COX-2) inhibitor meloxicam for treatment of postoperative oral surgical pain was assessed in a randomized controlled trial. Patients undergoing unilateral mandibular 3rd molar extraction surgery were allocated to 3 groups, A, B and C. After oral premedication of meloxicam 10 mg in group A, ampiroxicam 27 mg in group B and placebo in group C, surgery was completed within 30 min under local anaesthesia using 2% lidocaine. For postoperative pain relief the patients were allowed to take oral loxoprofen (60 mg per tablet). Postoperative pain was evaluated at the clinic on the 1st, 7th and 14th postoperative day (POD) using a visual analogue scale (VAS), as was the number of loxoprofen tablets consumed, and the results were compared among the 3 groups with statistical significance of P<0.05. VAS scores on 1 POD were significantly lower in group A than in group C. Loxoprofen consumption on the day of surgery and 1 POD was significantly lower in group A than in group C (P<0.01). Total analgesic consumption was significantly lower in groups A and B than in group C (P<0.02). The COX-2 inhibitor, meloxicam 10 mg used for premedication reduced postoperative pain compared with control in oral surgery.

Administration, Oral↗

PubMed2006

Antiangiogenic activity of BAI1 in vivo: implications for gene therapy of human glioblastomas.

Glioblastomas are the most common primary brain tumors in adults. These tumors exhibit a high degree of vascularization, and malignant progression from astrocytoma to glioblastoma is often accompanied by increased angiogenesis and the upregulation of vascular endothelial growth factor and its receptors. In this study, we investigated the in vivo antiangiogenic and antitumor effects of brain-specific angiogenesis inhibitor 1 (BAI1) using human glioblastoma cell lines. Glioblastoma cells were transduced with an adenoviral vector encoding BAI1 (AdBAI1), and Northern and Western blot analyses, respectively, demonstrated BAI1 mRNA and protein expression in the transduced tumor cells. Using an in vivo neovascularization assay, we found that angiogenesis surrounding AdBAI1-transduced glioblastoma cells transplanted into transparent skinfold chambers of SCID mice was significantly impaired compared to control treated cells. Additionally, in vivo inoculation with AdBAI1 of established subcutaneous or intracerebral transplanted tumors significantly impaired tumor growth and promoted increased mouse survival. Morphologically, the tumors exhibited signs of impaired angiogenesis, such as extensive necrosis and reduced intratumoral vascular density. Taken together, these data strongly indicate that BAI1 may be an excellent gene therapy candidate for the treatment of brain tumors, especially human glioblastomas.

Adenoviridae↗

PubMed2005

Multiband superconductivity in the heavy fermion compound PrOs4Sb12.

The thermal conductivity of the heavy fermion superconductor Pr(Os(4)Sb(12) was measured down to T(c)/40 throughout the vortex state. At lowest temperatures and for magnetic fields H approximately 0.07H(c2), already 40% of the normal state thermal conductivity is restored. This behavior (similar to that observed in MgB2) is a clear signature of multiband superconductivity in this compound.

Journal Article↗

PubMed2005

Line nodes in the superconducting gap function of noncentrosymmetric CePt3Si.

The superconducting gap structure of recently discovered heavy fermion CePt(3)Si without spatial inversion symmetry was investigated by thermal transport measurements down to 40 mK. In zero field a residual T-linear term was clearly resolved as T --> 0, with a magnitude in good agreement with the value expected for a residual normal fluid with a nodal gap structure, together with a T2 dependence at high temperatures. With an applied magnetic field, the thermal conductivity grows rapidly, in dramatic contrast to fully gapped superconductors, and exhibits one-parameter scaling with T/sqrt[H]. These results place an important constraint on the order parameter symmetry; that is, CePt(3)Si is most likely to have line nodes.

Journal Article↗

PubMed2005

Thermal transport in the hidden-order state of URu2Si2.

We present a study of thermal conductivity in the normal state of the heavy-fermion superconductor URu2Si2. Ordering at 18 K leads to a steep increase in thermal conductivity and (in contrast with all other cases of magnetic ordering in heavy-fermion compounds) to an enhancement of the Lorenz number. By linking this observation to several other previously reported features, we conclude that most of the carriers disappear in the ordered state and this leads to a drastic increase in both the phononic and electronic mean free path.

Journal Article↗

PubMed2004

Flux-line lattice distortion in PrOs4Sb12.

We report that the flux-line lattice in the cubic superconductor Pr(Os4Sb12 is strongly distorted from an ideal hexagonal lattice at very low temperatures in a small applied field. We attribute this to the presence of gap nodes in the superconducting state on at least some Fermi-surface sheets.

Journal Article↗

PubMed2004

Giant Nernst effect in CeCoIn5.

We present a study of Nernst and Seebeck coefficients of the heavy-fermion superconductor CeCoIn5. Below 18 K, concomitant with a field-dependent Seebeck coefficient, a large sublinear Nernst signal emerges with a magnitude drastically exceeding what is expected for a multiband Fermi-liquid metal. In the mixed state, in contrast with all other superconductors studied before, this signal overwhelms the one associated with the motion of superconducting vortices. The results point to a hitherto unknown source of transverse thermoelectricity in strongly interacting electrons.

Journal Article↗

PubMed2003

Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12.

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.

Journal Article↗

PubMed2003

Effective transduction and stable transgene expression in human blood cells by a third-generation lentiviral vector.

Difficulty in gene transduction of human blood cells, including hematopoietic stem cells, has hampered the development of gene therapy applications for hematological disorders, encouraging the development and use of new gene delivery systems. In this study, we used a third-generation self-inactivating (SIN) lentiviral vector system based on human immunodeficiency virus type 1 (HIV-1) to improve transduction efficiency and prevent vector-related toxicity. The transduction efficiency of the HIV-1-based vector was compared directly with the Moloney murine leukemia virus (MLV) SIN vector in human leukemia cell lines. Initial transduction efficiencies were almost 100% for the HIV and less than 50% for the MLV vectors. Similar results were observed in 11 types of primary cells obtained from leukemia or myeloma patients. Transgene expression persisted for 8 weeks in cells transduced with the HIV vector, but declined with the MLV vector. In addition, resting peripheral blood lymphocytes and CD34(+) hematopoietic cells were transduced successfully with the HIV vector, but not with the MLV vector. Finally, we confirmed vector gene integration in almost all colony-forming cells transduced with the HIV vector, but not with the MLV vector. In conclusion, this lentiviral vector is an excellent gene transduction system for human blood cells because of its high gene transduction and host chromosome integration efficiency.

Cells, Cultured↗

PubMed2003

Interindividual variation in the ratio between plasma morphine and its metabolites in cancer patients.

In 25 cancer patients treated with slow-release oral morphine and in 10 cancer patients treated with continuous infusion of morphine, plasma steady-state concentrations of morphine (M), morphine-3-glucuronide (M-3-G) and morphine-6-glucuronide (M-6-G) were determined by high-performance liquid chromatography. Blood samples were withdrawn at 0, 2 and 6 h after oral administration in patients treated with slow-release oral morphine and once or twice a day in patients treated with continuous infusion of morphine. In four cancer patients treated with continuous infusion of morphine, in order to analyze chronopharmacokinetic variability, the M-3-G/M ratio was observed at 12:00 h and 24:00 h. No significant changes were observed in M-3-G/M ratios and M-6-G ratios at 0, 2, and 6 h after oral administration of morphine. The M-3-G/M ratio (38.6 +/- 25.7) in the oral morphine group was significantly higher than that (15.3 +/- 12.9) in the continuous infusion group (p < 0.01). There was an approximately 10-fold interindividual variation in the M-3-G/M ratio both in the continuous infusion group and in the oral morphine group. These results suggest that the activity of UDP glucuronosyltransferase 2B7 in the intestinal metabolism of morphine may play an active part in a large interindividual variation in the ratio of metabolites to morphine. Further studies are needed to clarify this hypothesis.

Administration, Oral↗

PubMed2002

Gap function with point nodes in borocarbide superconductor YNi2B2C.

To determine the superconducting gap function of YNi2B2C, the c-axis thermal conductivity kappa(zz) was measured in H rotated in various directions. The angular variation of kappa(zz) in H rotated within the ab plane shows a peculiar fourfold oscillation with narrow cusps. The amplitude of this fourfold oscillation becomes very small when H is rotated conically around the c axis with a tilt angle of 45 degrees. These results provide the first compelling evidence that the gap function has point nodes located along the a and b axes. This unprecedented gap structure challenges the current view on the pairing mechanism.

Journal Article↗

PubMed2001

Superconducting gap structure of kappa-(BEDT-TTF)2Cu(NCS)2 probed by thermal conductivity tensor.

The thermal conductivity of organic superconductor kappa-(BEDT-TTF)2Cu(NCS)2 (Tc = 10.4 K) has been studied in a magnetic field rotating within the 2D superconducting planes with high alignment precision. At low temperatures ( T < or = 0.5 K), a clear fourfold symmetry in the angular variation, which is characteristic of a d-wave superconducting gap with nodes along the directions rotated 45 degrees relative to the b and c axes of the crystal, was resolved. The determined nodal structure is inconsistent with recent theoretical predictions of superconductivity induced by the antiferromagnetic spin fluctuation.

Journal Article↗

PubMed2001

Synthesis of 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl)adenine (FddA) via a purine 3'-deoxynucleoside.

A synthesis of 9-(2,3-dideoxy-2-fluoro-beta-D-threo-pentofuranosyl)adenine (1, FddA) via a 6-chloro-9-(3-deoxy-beta-D-erythro-pentofuranosyl)-9H-purine (9), which was readily obtained from inosine (5), is described. Fluorination at the C2'-beta position of the purine 3'-deoxynucleoside with diethylaminosulfur trifluoride was improved by the introduction of a 6-chloro group and proceeded in moderate yield. Purine 3'-deoxynucleoside derivatives were also subjected to nucleophilic reactions with triethylamine trihydrofluoride and gave the desired fluorinated nucleoside in good yield. The safety and yield of the fluorination process were greatly improved by the use of triethylamine trihydrofluoride. The influence of the sugar ring conformation and 6-chloro group on the rate of the nucleophilic reaction against elimination are also discussed.

Anti-HIV Agents↗

PubMed2001

Angular position of nodes in the superconducting gap of quasi-2D heavy-fermion superconductor CeCoIn5.

The thermal conductivity of the heavy-fermion superconductor CeCoIn5 has been studied in a magnetic field rotating within the 2D planes. A clear fourfold symmetry of the thermal conductivity which is characteristic of a superconducting gap with nodes along the ( +/- pi,+/- pi) directions is resolved. The thermal conductivity measurement also reveals a first-order transition at H(c2), indicating a Pauli limited superconducting state. These results indicate that the symmetry most likely belongs to d(x(2)-y(2)), implying that the anisotropic antiferromagnetic fluctuation is relevant to the superconductivity.

Journal Article↗

PubMed2001

Superconducting gap structure of spin-triplet superconductor Sr2RuO4 studied by thermal conductivity.

To clarify the superconducting gap structure of the spin-triplet superconductor Sr2RuO4, the in-plane thermal conductivity has been measured as a function of relative orientations of the thermal flow, the crystal axes, and a magnetic field rotating within the 2D RuO2 planes. The in-plane variation of the thermal conductivity is incompatible with any model with line nodes vertical to the 2D planes and indicates the existence of horizontal nodes. These results place strong constraints on models that attempt to explain the mechanism of the triplet superconductivity.

Journal Article↗

PubMed2001

Low energy quasiparticle excitation in the vortex state of borocarbide superconductor yni2b2c.

We measured the heat capacity C(p) and microwave surface impedance Z(s) in the vortex state of YNi2B2C. In contrast to conventional s-wave superconductors, C(p) shows a square root[H] dependence. This square root[H] dependence persists even after the introduction of the columnar defects which change the electronic structure of the vortex core regime and destroy the regular vortex lattice. On the other hand, flux flow resistivity is nearly proportional to H. These results indicate that the vortex state of YNi2B2C is fundamentally different from the conventional s-wave counterparts, in that the delocalized quasiparticle states around the vortex core are important, similar to d-wave superconductors.

Journal Article↗

PubMed2001

Haematopoietic progenitor cells from the common marmoset as targets of gene transduction by retroviral and adenoviral vectors.

To establish a new non-human primate model for human cytokine and gene therapy, we characterized lymphocytes and haematopoietic progenitor cells of the small New World monkey, the common marmoset. We first assessed the reactions of marmoset bone marrow (BM) and peripheral blood (PB) cells to mouse anti-human monoclonal antibodies (mAbs) for the purpose of isolating marmoset lymphocytes and haematopoietic progenitor cells. Both cell fractions stained with CD4 and CD8 mAbs were identified as lymphocytes by cell proliferation assay and morphological examination. Myeloid-specific mAbs such as CD14 and CD33 did not react with marmoset BM and PB cells. No available CD34 and c-kit mAbs could be used to purify the marmoset haematopoietic progenitor cells. Furthermore, we studied the in vitro transduction of the bacterial beta-galactosidase (LacZ) gene into CFU-GM derived from marmoset BM using retroviral and adenoviral vectors. The transduction efficiency was increased by using a mixed culture system consisting of marmoset BM stromal cells and retroviral producer cells. It was also possible to transduce LacZ gene into marmoset haematopoietic progenitor cells with adenoviral vectors as well as retroviral vectors. The percentage of adenovirally transduced LacZ-positive clusters was 15% at day 4 (multiplicity of infection=200), but only 1-2% at day 14. The differential use of viral vector systems is to be recommended in targeting different diseases. Our results suggested that marmoset BM progenitor cells were available to examine the transduction efficiency of various viral vectors in vitro.

Adenoviridae↗

PubMed2001

Successful treatment of bleeding due to ileal varices in a patient with hepatocellular carcinoma.

This case report concerns a 62-year-old female who was known to have cirrhosis. An endoscopic examination showed no evidence of haemorrhaging due to either oesophageal or gastric varices. Angiographic studies demonstrated extravasation from the ileal varices. There was a prominent arterio-portal shunt in the liver, and the shunt was considered to be a contributing factor to induce portal hypertension and variceal bleeding in the ileum. Therefore, transcatheter arterial embolization was performed, but was unsuccessful. As a result, the patient underwent a laparotomy, and a dilatating ileocaecal vein and a communicating ovarian vein were selectively ligated. Following the procedure, the haemorrhaging stopped and she then recovered. The patient is doing well 21 months after surgery at the time of writing.

Carcinoma, Hepatocellular↗