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Biomedical subjects

M Ishikawa

Publications and source records attributed to M Ishikawa.

At least 55 records · Page 3Linked to original sources
PubMed2002

Nucleation and growth of hydroxyapatite on an amino organosilane overlayer.

An amino organosilane overlayer (NH(2)-overlayer) was successfully processed on Si/SiO(2) substrates. Remarkable nucleation and growth of hydroxyapatite were found to take place on an NH(2)-overlayer after Si/SiO(2) substrates covered with the NH(2)-overlayer were soaked in supersaturated solutions with respect to Ca(2+) and PO(4)(3-) ions [1.0SBF (simulated body fluid), which contains similar compositions to that in a living body and 1.5SBF in which only Ca(2+) and PO(4)(3-) concentrations are 1.5 times than that in 1.0SBF]. The experimental results demonstrated that HAp nucleation on an NH(2)-overlayer is related to the electrostatic attractive force between positive NH(2)-overlayer surface and negative incipient HAp microparticles homogeneously nucleated in 1.5SBF solution at 50 degrees C. On the contrary, fewer HAp particles were observed on negatively charged "OH" terminated self-assembled monolayer (SAM) because of the repulsive interaction. The Ca/P molar ratios of HAp particles increased from 0.92 at the beginning of nucleation in 1.5SBF to 1.63 in 14 days after growth in 1.0SBF at 37 degrees C. After 14 days of soaking in 1.0SBF, a dense HAp film with the thickness up to 8.6 microm was formed on the NH(2)-overlayer.

Biocompatible Materials↗
PubMed2002

Glossopharyngeal neuralgia caused by adhesive arachnoid.

Glossopharyngeal neuralgia (GPN) is an uncommon disorder characterized by a severe lancinating pain commonly induced by swallowing. When the pain is resistant to medical management, surgical treatment such as microvascular decompression (MVD) or partial rhizotomy is performed. We report a case of glossopharyngeal neuralgia caused by adhesive arachnoid, in which pain disappeared solely by dissection of the peripheral arachnoid around the glossopharyngeal nerve.

Aged↗
PubMed2002

Effects of rolipram on in vivo dopamine receptor binding.

In order to clarify whether changes in brain concentrations of the second messenger cyclic AMP (cAMP) affect in vivo receptor binding in the brain, the effects of rolipram, a selective inhibitor of phosphodiesterase type 4 (PDE(4)), on dopamine receptor binding in the mouse brain were studied. Rolipram significantly decreased in vivo (3)H-SCH 23390 (dopamine D(1) selective radioligand) binding in the mouse striatum in a dose-dependent manner. In vivo saturation experiments together with the kinetic analysis of (3)H-SCH 23390 binding revealed that the apparent association rate constant (k(on)) for (3)H-SCH 23390 binding rather than the maximum number of binding sites available (B(max)) was decreased by rolipram. (3)H-N-methylspiperone (NMSP, dopamine D(2) selective radioligand) binding in the mouse striatum was also decreased by rolipram whereas no significant changes in (3)H-raclopride (dopamine D(2) selective radioligand) binding were observed. As (3)H-raclopride binding has been reported to be much more sensitive than (3)H-NMSP binding to competition by endogenous dopamine, the decreases in (3)H-SCH 23390 and (3)H-NMSP binding cannot be attributed to competitive inhibition by endogenous dopamine. These results indicate that changes in second messenger cAMP concentrations may affect the apparent bimolecular association rate constant (k(on)) of dopamine receptor binding in intact brain. This may be mediated by changes in the receptor micro-environment and altered actual free ligand concentration surrounding the receptors.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2002

A cytogenetic study of in-vitro matured murine oocytes after ICSI by human sperm.

BACKGROUND: The purpose of this study was to investigate the chromosomal complement and developmental potential of in-vitro matured murine oocytes following ICSI by human sperm. METHODS: Heterologous ICSI fertilization between mouse oocytes and human sperm was employed in order to overcome the reduced fertilization rates observed after conventional IVF due to zona hardening during in-vitro maturation, and to assess separately maternal and paternal chromosome complements. Cytogenetic analyses were performed in four types of oocytes: (i) in-vitro matured metaphase II (MII) oocytes; (ii) in-vivo matured MII oocytes; (iii) in-vitro matured oocytes after ICSI; (iv) in-vivo matured oocytes after ICSI. RESULTS: Activation rates after ICSI of in-vitro matured oocytes was lower than that of in-vivo matured oocytes (69.9 versus 97.2%, P < 0.01), and premature chromosomal condensation was only observed in in-vitro matured oocytes. However, there were no significant differences in developmental rates after successful activation between in-vivo and in-vitro matured ICSI oocytes (69.7 versus 76.6%). The incidences of aneuploidy and structural aberrations were similar between the ICSI embryos and non-ICSI (MII) oocytes. Furthermore, the frequency of chromosomal aberrations was not associated with in-vitro or in-vivo maturation. Similar analyses of paternal chromosomes indicated that there were no significant differences in the incidence of chromosomal aberrations between the embryos derived from in-vitro and in-vivo matured oocytes. CONCLUSIONS: These results suggest that in-vitro matured oocytes following ICSI do not lead to an increase in the frequency of aneuploidy and structural aberrations when human sperm are injected into mouse oocytes.

Aneuploidy↗
PubMed2002

Microdosimetry of epithermal neutron field at the Kyoto University reactor.

Microdosimetric spectra were measured in order to gain the microdosimetric parameters of some epithermal neutron fields. Changes in dose mean lineal energy YD as a function of depth of heavy water showed a trend of softening with heavy water of the beam. The neutron absorbed dose was obtained by using the frequency mean lineal energy. Results show good agreement with measurements with the activation method using gold foil. This study demonstrated how microdosimetric parameters change in radiation quality as a function of heavy water depth.

Deuterium Oxide↗
PubMed2002

Characterisation of an ultra-miniature counter for microdosimetric measurements in a therapeutic 400 MeV/A carbon beam.

Single event spectra of a clinical carbon beam have been measured by an ultra-miniature tissue-equivalent proportional counter (UMC). In order to cover the energy range of the Bragg peak, the incident energy of the carbon beam was degraded by aluminium plates. Single event spectra for carbon-events incident to the UMC were analysed and selected at several carbon energies using thin scintillation counters. It was found that the dose weighted lineal energy distributions have a doublet peak structure due to incident carbon beam and fragment contributions.

Calibration↗
PubMed2002

Effects of N-alpha-methyl-histamine on human H(2) receptors expressed in CHO cells.

BACKGROUND: Production of N-alpha-methyl-histamine (NAMH), a histamine H(3) receptor (H3R) agonist, is reportedly promoted in Helicobacter pylori infected human gastric mucosa. NAMH was suggested to act directly on histamine H(2) receptors (H2Rs) in animals to stimulate acid secretion and to be a H2R agonist. As H2Rs and H3Rs play different roles in gastric acid secretion, it is very important to verify that NAMH is a H2R agonist. AIMS: To determine whether NAMH is a H2R agonist, as well as a H3R agonist. METHODS: We used a Chinese hamster ovary (CHO) cell line expressing human H2Rs (CHO-H2R) and control CHO cells. Expression of human H2Rs was confirmed by tiotidine binding. cAMP production in CHO-H2R and control cells in response to histamine or NAMH was measured. cAMP production in response to 10(-7) M NAMH was also measured in the presence or absence of the H2R antagonist famotidine and the H3R antagonist thioperamide. RESULTS: NAMH dose dependently stimulated cAMP productions in CHO-H2R cells. This production was inhibited by famotidine but not by thioperamide. Control CHO cells were unresponsive to either histamine or NAMH. In addition, the effect of NAMH, in terms of cAMP production in CHO-H2R cells, was more potent than that of histamine-that is, with a lower EC(50) concentration and higher maximal cAMP production. Both NAMH and histamine, but not R-alpha-methyl-histamine, effectively inhibited [(3)H] tiotidine binding to CHO-H2R cells. CONCLUSIONS: NAMH, which is produced in the gastric mucosa by H pylori, is a potent H2R agonist as well as a H3R agonist.

Animals↗
PubMed2002

Importance of transition zone biopsies in patients undergoing ultrasound-guided prostate systemic biopsies for the first time.

INTRODUCTION: We analyze the efficacy of routine transition zone biopsies in patients undergoing ultrasound-guided systemic prostate biopsies for the first time because of a suspicious digital rectal examination or an elevated serum prostate-specific antigen (PSA) level. PATIENTS AND METHODS: During systemic prostate biopsy two or four additional transition zone biopsies were performed in 192 consecutive patients: in 182 because of a serum PSA concentration >4.1 ng/ml and in 10 because of a suspicious digital rectal examination and a serum PSA level <4.0 ng/ml. RESULTS: The overall prostate cancer detection rate was 37.5% (72/192). In 24 patients (33.3%), cancer was only detected in the peripheral zone, in 3 (4.2%) only in the transition zone, and in 45 (62.5%) in both zones. CONCLUSION: Transition zone biopsies performed at the first time of systemic prostate biopsy seem to have a low efficacy.

Aged↗
PubMed2002

Lipo-prostaglandin E1 is absorbed by vascular smooth muscle cells and may enhance re-endothelialization of vein grafts.

BACKGROUND: Enhancement of re-endothelialization inhibits the progression of intimal hyperplasia. We investigated uptake of Lipoprostaglandin E(1) (LPGE(1)) by endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and effects of the LPGE(1) on re-endothelialization of vein grafts. METHODS: Primary cultured ECs and VSMCs were obtained from mongrel dogs, and incubated in mediums containing 0.5, 5, 50, and 250 ng/ml of DiI-LPGE(1) (DLPGE(1)); its uptake was visualized by the standard rhodamine excitation, and assessed by flow cytometry. In an implantation study, the bilateral femoral veins of 18 animals were implanted into the femoral artery, and the animals were given 0.2 microg/kg LPGE(1) for 2 weeks. Percentages of EC coverage area of the grafts (%EC) were measured by silver nitrate staining at intervals of 3, 7, and 21 days after implantation. RESULTS: VSMCs showed significant uptake in all of the mediums containing DLPGE(1), whereas the ECs revealed no fluorescence. In flow cytometry, histograms of VSMCs showed a specific notch of DLPGE(1), which increased the height according to the grade of the concentrations. The notch did not appear in the histograms of the ECs incubated with any concentration nor in the VSMCs incubated in control medium. These results suggested that LPGE(1) is predominantly absorbed by the VSMCs and exuded PGE(1) then acts on the VSMCs itself and on ECs alike. The %EC at 7 days was 58.4+/-1.9% in the DLPGE(1) group and 31.6+/-6.8% in controls (p<0.05) showing a significant enhancing effect of DLPGE(1) on re-endothelialization of the vein grafts. CONCLUSIONS: In an animal model, daily administration of LPGE(1) resulted in significant enhancement of vein graft re-endothelialization. LPGE(1) was absorbed by the VSMCs, whereas the ECs showed no uptake, therefore the enhancement is probably due to a paracrine effect of VSMCs.

Alprostadil↗
PubMed2001

Ferromagnetic exchange coupling of vanadium(IV) dpi spins across pyrimidine rings: dinuclear complexes of oxovanadium(IV) bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionate) bridged by pyrimidine derivatives.

Dinuclear oxovanadium(IV) complexes bridged by pyrimidine derivatives, L[VO(hfac)(2)](2) [L = pyrimidine (PM), 4-methylpyrimidine (MPM), 4,6-dimethylpyrimidine, 4-aminopyrimidine, and quinazoline; hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate], were synthesized and characterized. All of them showed intramolecular ferromagnetic interaction, and the magnetic susceptibilities were analyzed on the basis of the singlet-triplet model, giving 2J/k(B) = 2.2-5.5 K. PM[VO(hfac)(2)](2) crystallized in a monoclinic space group C2/c with a = 34.092(2), b = 6.9783(4), and c = 16.4940(9) A, beta = 109.104(1) degrees, V = 3707.8(4) A(3), and Z = 4 for C(24)H(8)F(24)N(2)O(10)V(2), and MPM[VO(hfac)(2)](2) gave isomorphous crystals. A semiempirical calculation study based on the determined structure suggests the presence of dpi-ppi interaction between vanadium and pyrimidine nitrogen atoms. Ferromagnetic coupling is explained in terms of a spin-polarization mechanism across the pyrimidine bridge. The intermolecular ferromagnetic interaction of PM[VO(hfac)(2)](2) can be interpreted by the contact between the spin-polarized pyrimidine moiety and the oxovanadium oxygen atom in an adjacent molecule.

Journal Article↗
PubMed2001

Association of the mitochondrial DNA 5178 A/C polymorphism with serum lipid levels in the Japanese population.

As one approach to exploring whether the mitochondrial DNA 5178 adenine/cytosine (mt5178 A/C) polymorphism is associated with atherosclerosis, we genotyped 461 healthy Japanese individuals and studied the relationship of mt5178 A/C genotypes to serum lipid levels. Blood specimens were obtained after at least a 12-h fasting period from the subjects. The mt5178 A/C was genotyped by the polymerase chain reaction/restriction fragment length polymorphism method. The relative frequency of mt5178 A was 41.6% (192/461) and of mt5178 C was 58.4% (269/461). After adjustments for age and body mass index, the high-density lipoprotein cholesterol concentration in males carrying mt5178 A was significantly higher than that in males carrying mt5178 C ( P=0.026). The tryglyceride (TG) concentration in females carrying mt5178 A was significantly lower than that in females carrying mt5178 C ( P=0.012). This difference in the TG level between the two genotypes was more evident in postmenopausal females than in premenopausal females. Mt5178 A seems to have an antiatherogenic effect. This is the first genetic epidemiological report on the association of mt5178 A/C polymorphism with serum lipid levels in the Japanese population.

Adenine↗
PubMed2001

Relationships between outcomes of conservative treatment and magnetic resonance imaging findings in patients with mild cervical myelopathy caused by soft disc herniations.

STUDY DESIGN: A retrospective follow-up study of conservatively treated patients with mild cervical myelopathy caused by cervical soft disc herniation. OBJECTIVE: To investigate the outcome of conservative treatment for patients with mild myelopathy caused by cervical soft disc herniation and to evaluate usefulness of magnetic resonance findings in the prediction of the outcomes. SUMMARY OF BACKGROUND DATA: Recent studies on conservative treatment for cervical soft disc herniation have focused mainly on radiculopathy, and not on myelopathy. METHODS: Twenty-seven patients with mild cervical myelopathy secondary to cervical soft disc herniation were treated conservatively for more than 6 months by cervical bracing and restriction of daily activities. Of the 27 patients, 17 patients (Group A) underwent conservative treatment only and it was associated with improvement in their neurologic deficits, while the other 10 patients (Group B) ultimately underwent decompression surgery because of neurologic deterioration. Comparisons between the two groups were made in regard to JOA scores, patient satisfaction, and magnetic resonance findings, including location of the disc herniation (focal or diffuse in the sagittal plane, median or paramedian in the axial plane). RESULTS: The JOA scores were 13.6 +/- 1.6 in Group A and 14.1 +/- 1.6 in Group B before treatment, 14.9 +/- 1.0 and 12.9 +/- 2.1, respectively, at 3 months, and 16.2 +/- 0.8 and 16.0 +/- 1.2, respectively, at the final follow-up. The JOA scores at 3 months were significantly lower in Group B than in Group A. Satisfaction with the results of treatment at the final follow-up was reported by 77% of the patients in Group A and 90% in Group B. Focal-type herniation was present in 47% of the patients in Group A and 70% in Group B, while median-type herniation was diagnosed in 77% in Group A and 30% in Group B. Follow-up magnetic resonance imaging of the patients in Group A showed spontaneous regression of a herniated mass in 10 patients (59%). Diffuse-type herniations were more likely to regress spontaneously than focal-type herniations (78% vs. 37%). CONCLUSIONS: Conservative treatment is an effective treatment option for mild cervical myelopathy caused by cervical soft disc herniation. A good outcome can be expected in patients with a median-type and/or diffuse-type herniation on magnetic resonance imaging.

Adult↗
PubMed2001

Discovery of a novel CCR3 selective antagonist.

In searching for a novel CCR3 receptor antagonist, we designed a library that included a variety of carboxamide derivatives based on the structure of our potent antagonists for human CCR1 and CCR3 receptors, and screened the new compounds for inhibitory activity against 125I-Eotaxin binding to human CCR3 receptors expressed in CHO cells. Among them, two 2-(benzothiazolethio)acetamide derivatives (1a and 2a) showed binding affinities with IC50 values of 750 and 1000 nM, respectively, for human CCR3 receptors. These compounds (1a and 2a) also possessed weak binding affinities for human CCR1 receptors. We selected la as a lead compound for derivatization to improve in vitro potency and selectivity for CCR3 over CCRI receptors. Derivatization of la by incorporating substituents into each benzene ring of the benzothiazole and piperidine side chain resulted in the discovery of a compound (1b) exhibiting 820-fold selectivity for CCR3 receptors (IC50 = 2.3 nM) over CCR1 receptors (IC50 = 1900 nM). This compound (1b) also showed potent functional antagonist activity for inhibiting Eotaxin (IC50 = 27 nM)- or RANTES (IC50 = 13 nM)-induced Ca2+ increases in eosinophils.

Acetamides↗
PubMed2001

Atomic resolution noncontact atomic force and scanning tunneling microscopy of TiO2(110)-(1 x 1) and - (1 x 2): simultaneous imaging of surface structures and electronic states.

We present simultaneous imaging of TiO2(110)-(1 x 1) and - (1 x 2) using noncontact atomic force microscopy (NC-AFM) and scanning tunneling microscopy (STM). The surface topography was imaged under NC-AFM feedback, while the surface electronic states were imaged by STM. The image contrasts of NC-AFM and STM were antiphase in (1 x 1) and in phase in (1 x 2). The uppermost oxygen and Ti atoms underneath were, respectively, imaged by NC-AFM and STM. The NC-AFM image contrast was close to the true surface topography in (1 x 2), but reduced in (1 x 1).

Journal Article↗
PubMed2001

Unnatural base pairs for specific transcription.

An unnatural base pair of 2-amino-6-(N,N-dimethylamino)purine (designated as x) and pyridin-2-one (designated as y) has been developed for specific transcription. The ribonucleoside triphosphates of y and a modified y, 5-methylpyridin-2-one, are selectively incorporated into RNA opposite x in the templates by T7 RNA polymerase. In addition, the sequences of the DNA templates containing x can be confirmed by a dideoxynucleotide chain-terminator method supplemented with the deoxynucleoside triphosphate of y. The bulky dimethylamino group of x in the templates effectively eliminates noncognate pairing with the natural bases. These results enable RNA biosynthesis for the specific incorporation of unnatural nucleotides at the desired positions.

Base Pairing↗
PubMed2001

On-demand droplet spotter for preparing pico- to femtoliter droplets on surfaces.

A droplet spotter for on-demand generation of pico- to femtoliter droplets was developed to meet the requirement for high-density spotting of chemicals on a surface. Our droplet spotter involves applying a approximately 1000-V and approximately 10-ms pulse voltage to the tip of a capillary tube (o.d. approximately 18 microns; i.d. approximately 11 microns) supplied with water or a dye solution. The capability of the spotter was demonstrated by preparing a microarray of dye molecules. The microarray was prepared by spotting approximately 30-fL droplets of a dye solution on a surface at the density of one spot per 20 x 20 micron 2.

Journal Article↗