Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 181 records · Page 10Linked to original sources

PubMed1998

Syntheses and preventive effects of analogues related to 1alpha,25-dihydroxy-2beta-(3-hydroxypropoxy)vitamin D3 (ED-71) on bone mineral loss in ovariectomized rats.

Analogues related to 1alpha,25-dihydroxy-2beta-(3-hydroxypropoxy)vitamin D3 (ED-71) (2), 26,27-dimethyl ED-71 (3) and 26,27-diethyl ED-71 (4), were synthesized from lithocholic acid (5). In the study of the preventive effects of these analogues and ED-71 (2) on bone mineral loss in ovariectomized rats, 26,27-dimethyl ED-71 (3) showed the most potent activity.

Animals↗

PubMed1998

Burkitt's lymphoma involving the mandible: report of a case and review of Japanese cases.

A Japanese case of Burkitt's lymphoma is presented. The intraoral and panoramic images showed alveolar bone destruction with an infiltrative border, displacement of lower molars, root resorption, and loss of lamina dura and the follicular cortex of a developing tooth, similar to descriptions in previous reports. Computed tomography revealed that a primary lesion occupied the mandible and extended to the muscles of facial expression and to the sublingual and submandibular spaces. Another soft tissue mass was evident in the contralateral parapharyngeal space. Results of a survey of the Japanese literature are also presented; they indicate differences in the clinical features between Japanese cases and African and American cases of Burkitt's lymphoma.

Anti-Inflammatory Agents↗

PubMed1998

Visualization of PEO-PBLA-pyrene polymeric micelles by atomic force microscopy.

PURPOSE: To directly visualize and evaluate the aqueous block copolymeric micelles, poly(ethylene oxide)-poly(beta-benzyl L-aspartate) (PEO-PBLA) chemically conjugated with pyrene fluorescence molecule, by nanotechnology of atomic force microscopy (AFM). METHODS: The block copolymers' PEO-PBLA-Pyrene was first synthesized by reacting with pyrene sulfonyl chloride and PEO-PBLA in tetrahydrofuran (THF) solution and were identified by GPC reflect index, UV and fluorescence detectors. The characterization of physical and chemical properties of PEO-PBLA-Pyrene polymeric micellar solution were examined by the dynamic light scattering (DLS) and critical micelles concentrations (CMC). In addition, the nanotechnology of AFM was used to directly visualize the size and shape of nanopolymeric micelles. RESULTS: The pyrene fluorescence molecule were successfully conjugated at the amino group of the end of PBLA chain by GPC with three different detectors. The size of the aqueous PEO-PBLA-Pyrene polymeric micelles was detected around 57 nm with unimodal distribution by DLS measurement. As a result of this finding, the CMC test was also found out that the fluorescence intensity was increasing around 0.01 approximately 0.05 mg/ml. Using AFM evaluation of polymeric micellar solution, the morphology of aqueous PEO-PBLA-Pyrene polymeric micelles was observed on round shape and with the narrow dispersity of size range 50 approximately 80 nm. CONCLUSIONS: The presence of PEO-PBLA copolymers with pyrene in an aqueous system formed in a spherical and nano range of polymeric micelles.

Micelles↗

PubMed1998

Light-dependent expression of pinopsin gene in chicken pineal gland.

The phase of a circadian clock in the chicken pineal gland is reset by an environmental light signal, which is captured by the pineal photoreceptive molecule(s). Here we show that the mRNA level of pinopsin, a predominant photoreceptive molecule in the pineal gland, undergoes a diurnal fluctuation in chickens maintained on a light/dark cycle. The mRNA levels in the light were approximately six times higher than those in the dark. This fluctuation was not observed in constant darkness, where the mRNA levels remained low. Subsequent light exposure of chickens increased the amount of pinopsin mRNA regardless of the circadian time. Clearly, the expression of pinopsin gene is controlled by a light signal, independent of the circadian clock. In vitro experiments using cultured pineal glands isolated from the visual system also revealed the light-dependent increase in pinopsin mRNA level, indicating that the pineal photoreceptive molecule(s) is responsible for the induction. These results demonstrate the presence of a feedback loop through which the light signal captured by pinopsin stimulates the transcription of its own gene in the chicken pineal gland. In contrast, pinopsin protein remained at an almost constant level in chickens maintained under the same light/dark cycles. The protein level, however, decreased to approximately 50% of the light/dark level under constant darkness and subsequently increased upon exposure to light after the dark period. It is suggested that, under the light/dark cycles, the pinopsin protein level is kept constant by the light-dependent synthesis, which would compensate for a possible degradation of pinopsin in the daytime.

Animals↗

PubMed1998

Relations among interaural cross-correlation coefficient (IACCE), lateral fraction (LFE), and apparent source width (ASW) in concert halls.

Relations are determined between one of the important subjective attributes of concert hall acoustics, the apparent source width, ASW, and three acoustical measures, interaural cross-correlation coefficient IACCE, LFE, and strength factor G. Although these measures previously have been found to correlate with ASW, their relations with it have not been examined sufficiently, especially in respect to their frequency characteristics. Herein, ASW's are directly determined for electronically reproduced musical sound fields with extensive ranges of values for IACCE and LFE. Investigated as parameters are angles of incidence, the time delay difference between a pair of symmetric early lateral reflections, and the number of early lateral reflections. These studies indicate the relative efficacy of IACCE and LFE for determining ASW under conditions that are realistically encountered in concert halls. The results were compared with measured IACCE's, LFE's, and also the strength factor G's in existing concert halls. It is concluded that the arithmetic average of [1-IACCE]'s at 500, 1 k and 2 k Hz combined with the strength factor Glow of the sound field at frequencies below 250 Hz are physical measures highly correlated with the subjective rank ordering of concert halls and that they cover the effects on ASW of the entire octave-band frequency range from 125 to 4 k Hz.

Acoustics↗

PubMed1998

Two-dimensional manipulation of confluently cultured vascular endothelial cells using temperature-responsive poly(N-isopropylacrylamide)-grafted surfaces.

Temperature-responsive hydration/dehydration changes in surface-grafted poly(N-isopropylacrylamide) (PIPAAm) were utilized for hydrophilic/hydrophobic surface property alterations in cell culture. In this report, we utilized PIPAAm-grafted surfaces to recover confluently-cultured vascular endothelial cells as coherent monolayers from this cell culture substrate and to transfer to new cell culture substrates. For this purpose, we used two different methods to recover and transfer cell monolayer cultures: (1) chitin membranes used as an apical side cell support during cultured cell transfer, allowing cell basal side reattachment to new culture substrates after transfer; and (2) a cell culture insert (porous PET) used as both a support as well as new substrate, allowing basal surfaces of cultured cells to be exposed to the medium after transfer. In both cases, all cells grown on PIPAAm-grafted surfaces detach completely with maintenance of basement membrane-like structure. Recovered cells attach to the second culture surfaces, covering more than 60% of the new substrate, and retain approximately 90% viability and their original function as judged from tissue-type plasminogen activator secretion. This technique could be utilized to prepare novel bioartificial organs as well as cell co-culture systems by multi-layering different cell types to mimic tissue structures for tissue engineering.

Acrylic Resins↗

PubMed1998

Minimized platelet interaction with poly(2-hydroxyethyl methacrylate-block-4-bis(trimethylsilyl)methylstyrene) hydrogel showing anomalously high free water content.

Novel hydrophilic-hydrophobic block copolymers - poly(2-hydroxyethyl methacrylate-block-4-bis(trimethylsilyl)methylstyrene) (poly(HEMA-block-BSMS) or BH polymer) - were prepared as materials potentially useful for blood-contacting devices. Among the BH(X) series including poly(HEMA) itself, platelet adhesion and activation are minimum on the surface of BH(10), the block copolymer composed of 10 mol% of the hydrophobic segment. The unique physicochemical characteristics of BH(10) such as the high free water content and the increased mobility of PHEMA segments seem to play an important role in the prevention of platelet adhesion and activation. The water content of BH(10) was twice that of poly(HEMA) itself, even in the presence of 10 mol% of the hydrophobic moiety [poly(BSMS)]. Further, an anomalous increase in free water content was observed for the BH(10) sample measured by DSC. The glass transition temperature of BH(10) in the dry state was determined to be c. 10 degrees C, which was much lower than that observed for each of the homopolymers (c.f.: Tg [poly(HEMA)] = 70 degrees C; Tg [poly(BSMS)] = 160 degrees C), suggesting an increased mobility of tethered PHEMA segments in the BH(10) film.

Acrylic Resins↗

PubMed1998

Retinal pigmented epithelium cultures on thermally responsive polymer porous substrates.

A cross-linkable co-polymer of UV-sensitive 4-(N-cinnamoylcarbamide)methylstyrene (CCMS) and N-isopropylacrylamide (NIPAAm), was applied to porous tissue culture inserts. Surface chemical analyses of the inserts show an introduction of a thermally responsive polymer comparable to that on similarly incorporated non-porous polystyrene surfaces. Contact angle measurements as well as atomic force microscopy show a surface change in response to changing temperature in an aqueous environment, from hydrophilic, extended polymer chains below 32 degrees C to a dense hydrophobic film above 32 degrees C. Cell growth on porous inserts allowed measurement of cell expression, such as transepithelial resistance and fluid transport, which are not observable on cells from non-porous surfaces. Cultures of retinal pigmented epithelium (RPE) were able to restore an environment similar to in vivo by forming a tight junction barrier membrane upon confluence at 37 degrees C, as observed by changes in morphology, transepithelial resistance, and directionally-specific fluid transport. In addition, cells cultured on these surfaces detached as an oriented polarized sheet when the inserts were brought to 20 degrees C. This cell sheet was transplanted to other tissue culture surface without polymer detachment or dissolution, or cell damage caused by traditional detachment methods using proteolytic enzymes.

Acrylic Resins↗

PubMed1998

Singly dehydroxylated A-ring analogues of 19-nor-1alpha,25-dihydroxyvitamin D3 and 19-nor-22-oxa-1alpha,25-dihydroxyvitamin D3: novel vitamin D3 analogues with potent transcriptional activity but extremely low affinity for vitamin D receptor.

1Alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] mediates its biological activities through specific binding to the nuclear vitamin D receptor (VDR). The VDR, bound to 1alpha,25(OH)2D3, forms a heterodimer with a nuclear accessory factor, retinoid X receptor (RXR), and the complex subsequently binds to specific nucleotide sequences or a vitamin D-responsive element (VDRE) to induce gene transcriptions. Thus, an ideal analogue of 1alpha,25(OH)2D3 for therapeutic applications has been considered to be one which has a high binding affinity for VDR, thus forming a stable VDR/RXR complex, and binding strongly to VDRE. By contrast, we report here evidence contrary to this hypothesis. Several singly dehydroxylated A-ring analogues of 19-nor-1alpha,25-dihydroxyvitamin D3 and 19-nor-22-oxa-1alpha,25-dihydroxyvitamin D3, all of which have an extremely low binding affinity for VDR, and some of which lack the 1alpha-hydroxyl group that is considered to be essential for VDR-mediated gene expression, have greater or equivalent potencies to 1alpha,25(OH)2D3 for inhibiting the proliferation and inducing the differentiation of HL-60 cells, as well as inducing the transactivation of a luciferase reporter gene combining a rat 25-hydroxyvitamin D3 24-hydroxylase gene promoter containing two VDREs. The present findings open interesting possibilities as to the role of the VDR in the genomic action of 1alpha,25(OH)2D3 and the development of new 19-nor-analogues of 1alpha,25(OH)2D3.

Animals↗

PubMed1998

Hepatocyte growth factor in vitreous fluid of patients with proliferative diabetic retinopathy and other retinal disorders.

OBJECTIVE: To determine whether hepatocyte growth factor (HGF) is elevated in the vitreous fluid of patients with proliferative diabetic retinopathy (PDR). RESEARCH DESIGN AND METHODS: Vitreous fluid samples were obtained at the time of vitreoretinal surgery from 73 eyes of PDR patients and from 17 eyes of nondiabetic patients (control subjects) who had macular hole, rhegmatogenous retinal detachment, or epiretinal membrane (9, 4, and 4 eyes, respectively) but no associated proliferative vitreoretinopathy Stages of PDR were classified as active or quiescent. Concentrations of HGF and vascular endothelial growth factor (VEGF) in vitreous fluid were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Intravitreous concentrations of HGF (median [range]) were significantly higher in diabetic patients with PDR (6.00 ng/ml [0.75-22.21) than in control patients (2.86 ng/ml [0.75-5.801). Intravitreous concentrations of VEGF were also higher in diabetic patients with PDR (1.62 ng/ml [0.15-7.91) than in control patients (0.16 ng/ml [0.160.29]). Both VEGF and HGF concentrations were significantly higher in patients with active retinopathy than in those with quiescent retinopathy However, vitreous concentrations of HGF were unrelated to those of VEGE CONCLUSIONS: We found that levels of HGF in vitreous fluid of PDR patients are significantly higher than in nondiabetic patients and that the levels of HGF are elevated in the active PDR stage. This suggests that HGF stimulates or perpetuates neovascularization in PDR.

Diabetic Retinopathy↗

PubMed1998

Absorbability of calcium from a new calcium supplement prepared from bovine marrow-free bone in rats.

Powdered bovine marrow-free bone was completely solubilized with lactic and citric acids under reduced pressure. The resulting solution was lyophilized to obtain a stable powder form (total bone extract, TBE), and the calcium (Ca) absorbability of TBE from intestine was investigated in normal rats. Each animal perorally received 10 mg of Ca in 1 mL of distilled water as extrinsic 45Ca-labeled TBE, intrinsic 45Ca-labeled Ca lactate, or intrinsic 45Ca-labeled Ca carbonate. The amount of radioactivity in plasma was measured periodically up to 34 h after dosing, and pharmacokinetic parameters were calculated from the radioactivity in plasma. The time taken to reach the maximal 45Ca level (Tmax) did not differ among the three groups. The area under the plasma 45Ca level/time curve (AUC infinity) and the radioactivity at Tmax (Cmax) values for the TBE group were significantly higher than those of the Ca carbonate group. Similar results were observed between the Ca lactate and the Ca carbonate groups. No significant difference was observed in the AUC infinity and the Cmax values between the TBE and the Ca lactate groups. Radioactivity in a femur 34 h after dosing was highest in the Ca lactate group and lowest in the Ca carbonate group among the three groups. Both the TBE and the Ca lactate groups showed significant higher whole-body 45Ca retention than the Ca carbonate group did, although no significant difference was found between the TBE and the Ca lactate groups. These findings indicate that the Ca absorbability of TBE is almost comparable with that of Ca lactate and higher than that of Ca carbonate. Therefore TBE would be useful as a Ca supplement with relatively high absorbability from intestine.

Animals↗

PubMed1998

[Targeting of anticancer drug using intelligent polymers].

To fabricate the drug targeting system, it is very effective to combine passive targeting with intelligent polymeric system such as temperature-responsive polymers. We have been studying the passive targeting of anticancer drug bonded with or physically trapped in polymeric micelle derived from poly (ethylene oxide) (PEO) and poly (aspartic acid) block copolymer. On the other hand, Poly(N-isopropylacrylamide) (PIPAAm) is known to be a thermo-responsive polymer which has lower critical solution temperature (LCST, 32 degrees C). PIPAAm shows the reversible phase transition above and below LCST. Attempts to apply thermo-responsive drug carriers were made to enhance the site-specificity of polymeric micelle. Namely, novel type of polymeric micelle were prepared from block copolymers comprising N-isopropylacrylamide (IPAAm)-hydrophobic polymers. This temperature responsive micelles were expected to induce selective accumulation controlled by temperature modulation.

Acrylic Resins↗

PubMed1998

Interaction of beta-lactam antibiotics with H+/peptide cotransporters in rat renal brush-border membranes.

Two H+/peptide cotransporters, PEPT1 and PEPT2, are expressed in the kidney, mediating the renal tubular reabsorption of oligopeptides and beta-lactam antibiotics. We examined the interactions of beta-lactam antibiotics with peptide transporters in rat renal brush-border membranes by evaluating the inhibitory potencies of the antibiotics against glycylsarcosine transport. Western blot analysis revealed that PEPT1 and PEPT2 were expressed in the renal brush-border membranes with the apparent molecular masses of 75 and 105 kDa, respectively. Using renal brush-border membrane vesicles, the uphill transport of glycylsarcosine was observed in the presence of an inward H+ gradient and an inside-negative membrane potential. Two transport systems with high affinity (Km of 50 microM) and low affinity (Km of 1.2 mM) appeared kinetically to mediate the glycylsarcosine uptake. The inhibition constants of the antibiotics for glycylsarcosine transport were more closely correlated with those in stable LLC-PK1 cells transfected with rat PEPT2 rather than PEPT1 cDNA. The beta-lactam antibiotics with an alpha-amino group showed trans-stimulation effects on the glycylsarcosine uptake, suggesting that these antibiotics and glycylsarcosine share a common peptide transporter. However, the antibiotics lacking an alpha-amino group failed to show the trans-stimulation effect. It is concluded that amino-beta-lactam antibiotics at therapeutic concentrations interact predominantly with PEPT2 localized in the brush-border membranes of rat kidney.

Animals↗

PubMed1998

Lateral retropharyngeal node metastasis from carcinoma of the upper gingiva and maxillary sinus.

Clinically unsuspected metastases to the lateral retropharyngeal nodes from carcinomas of the upper gingiva or maxillary sinus were found in five patients on follow-up CT examinations. Such uncommon metastases may follow the afferent lymphatic channels from the palate or pharyngeal region or arrive by retrograde lymphatics from positive neck nodes. Careful examination of lateral retropharyngeal nodes may be required in cancers of these primary sites.

Aged↗

PubMed1998

[Targeting of anti-cancer drugs with nano-sized carrier system].

Feasibility of anticancer drug targeting to solid tumors with nano-sized drug carrier systems by a passive targeting mechanism is discussed. Selective delivery to solid tumor sites can be done by utilizing EPR effect (Enhanced Permeability and Retention effect) of solid tumor sites. Essential factors of carriers systems based on this mechanism is size and chemical character of carriers. Size and chemical character must be in a range of several nm to 200 nm and neutral or weakly negatively charged surface, respectively. Present status and future perspective of four types of nano-carrier systems (water-soluble polymer, nanosphere, liposome, and polymeric micelle) are described with recent developments of each system.

Animals↗

PubMed1997

Immunocytochemical identification of pinopsin in pineal glands of chicken and pigeon.

Pinopsin is a blue-sensitive photoreceptive molecule possibly involved in photic entrainment of the circadian pacemaker in the chicken pineal gland. To characterize pinopsin as a circadian photoreceptor, antibodies were raised against the C-terminal portion of pinopsin. As expected from the divergence of the amino acid sequence of this region, the resultant antibody cross-reacted with neither chicken rhodopsin nor red-sensitive cone pigment (chicken red). In Western blot analysis, the antibody stained a single band of 42-kDa protein in a detergent-extract of chicken pineal membranes, suggesting that pinopsin (calculated molecular weight, 38187) might be glycosylated and/or palmitoylated. Immunocytochemical examination of pineal sections of the chicken and the pigeon with this antibody revealed strong positive images for most of the membrane structures in the lumen of the follicles. This antibody also stained string- and bulb-shaped structures of the chicken parafollicular cells, the morphology of which resembles those of retinal photoreceptor cells. In contrast to the predominant distribution of pinopsin, a monoclonal antibody specific for chicken red stained a smaller number of membrane structures in the lumen of chicken pineal follicles. These results strongly suggest that the chicken pineal gland contains at least two types of photoreceptive molecules, pinopsin (major) and chicken red (minor). We show that the former molecule is localized in parafollicular pinealocytes and in the outer segments of pinealocytes that make contact with the follicular lumen.

Amino Acid Sequence↗

PubMed1997

Simplified method for the determination of 25-hydroxy and 1alpha,25-dihydroxy metabolites of vitamins D2 and D3 in human plasma. Application to nutritional studies.

A simplified method for the determination of 25-hydroxy and 1alpha,25-dihydroxy metabolites of vitamins D2 and D3 in human plasma was developed. Plasma samples were deproteinizated and applied to a Bond Elut C18OH cartridge to separate 25-hydroxyvitamin D (25-OH-D) and 1alpha,25-dihydroxyvitamin D [1,25(OH)2D] fractions. The 25-OH-D fraction was purified by a Bond Elut C18 cartridge and 25-OH-D2 and 25-OH-D3 were assayed by HPLC using a Zorbax SIL column. The 1,25(OH)2D fraction obtained above was subsequently applied to HPLC using a Zorbax SIL column to separate 1,25(OH)2D2 and 1,25(OH)2D3 fractions which were determined by a radioreceptor assay (RRA) using calf thymus receptor. The method was applied to nutritional studies.

25-Hydroxyvitamin D 2↗

PubMed1997

Temperature-responsive liquid chromatography. 2. Effects of hydrophobic groups in N-isopropylacrylamide copolymer-modified silica.

We recently reported the new concept of temperature-responsive liquid chromatography using temperature-responsive poly(N-isopropylacrylamide)-modified surfaces as high-performance liquid chromatography media with aqueous mobile phases. Incorporation of hydrophobic sites is an important factor to improve the efficacy (selectivity and retention) of temperature-responsive chromatography. Toward this goal, we have synthesized semitelechelic copolymers of N-isopropylacrylamide (IPAAm) and butyl methacrylate (BMA) having reactive terminal functional groups using telomerization. The lower critical solution temperatures of the copolymers shift to lower temperatures with increasing hydrophobic BMA content in the poly(IPAAm-co-BMA) relative to that of the IPAAm homopolymer. This temperature-responsive semitelechelic copolymer was grafted to the surface of (aminopropyl)silica through the reaction of activated ester-amine coupling. The polymer-modified silica was used as a column packing material. Separation of a mixture of five steroids having various hydrophobicities was investigated. Retention of steroids on poly(IPAAm-co-BMA)-modified columns is increased with an increase in column temperature. The capacity factors for steroids on the copolymer-modified silica beads was much larger than that on homopolymer PIPAAm-modified columns. The capacity factor for testosterone at 50 degrees C was 33.8 for poly(IPAAm-co-BMA) containing 5 mol% BMA, while that for the PIPAAm homopolymer was 15.0 at the same temperature. The influence of column temperature on steroid retention behavior on copolymer-modified stationary phases was significant compared with the case of homopolymer-modified columns. Furthermore, retention times for steroids increased remarkably with increasing BMA composition. The temperature-responsive elution behavior for the steroids was strongly affected by the hydrophobicity of the grafted polymer chains on silica surfaces. Possible protein separation in temperature-responsive liquid chromatography was explored using insulin chains A and B, and beta-endorphin fragment 1-27. On IBc-3.2-modified silica column, these three peptides were successfully separated at 30 degrees C with 0.5 M NaCl aqueous solution (pH 2.1) as mobile phase. The retention times of these peptides were related to the number of hydrophobic amino acid residues in the peptides. In the proposed chromatography system, elution of target substances is controlled only by a small change in column temperature without any further modification of the aqueous mobile phase.

Acrylamides↗