Search PubMed⌕ Search

Biomedical subjects

M Yoshinari

Publications and source records attributed to M Yoshinari.

At least 19 recordsLinked to original sources
PubMed2001

Sodium-coupled glucose transporter as a functional glucose sensor of retinal microvascular circulation.

To clarify the function of the Na(+)-coupled glucose transporter in the regulation of cellular tone of cultured retinal pericytes, we investigated the effects of extracellular glucose concentration on cell size. The surface area and diameter of cultured bovine retinal pericytes under different glucose concentrations were measured by using a light microscope with a digital camera. We also examined the effects of extracellular Na(+) and Ca(2+), inhibitors of the Na(+)-coupled glucose transporter and Na(+)-Ca(2+) exchanger, a Ca(2+) channel blocker, and nonmetabolizable sugars on cell size. The surface area and diameter of the cells changed according to extracellular glucose concentrations. alpha-Methyl glucoside, which enters the cell through the Na(+)-coupled glucose transporter, induced cellular contraction. However, the cells did not contract in response to 2-deoxyglucose, which enters the cell through a facilitated glucose transporter. Glucose-induced cellular contraction was abolished in the absence of extracellular Na(+) and Ca(2+). Moreover, phlorizin, an inhibitor of the Na(+)-coupled glucose transporter, and 2',4'-dichlorobenzamil-HCl, an inhibitor of the Na(+)-Ca(2+) exchanger, also abolished glucose-induced cellular contraction, whereas nicardipine, a Ca(2+) channel blocker, did not. Our results indicate that high extracellular glucose concentrations induce contraction of bovine retinal pericytes via Na(+) entry through a Na(+)-coupled glucose transporter, suggesting that the Na(+)-coupled glucose transporter may act as a functional glucose sensor of retinal microvascular circulation.>

Amiloride↗
PubMed2001

Immobilization of bisphosphonates on surface modified titanium.

The efficiency of surface modifications on the immobilization of bisphosphonates on titanium was investigated with Ca-ion implantation and thin hydroxyapatite coatings. The ALP activity of osteoblastic cells and the inhibitory effects on the initial adherence of P. gingivalis were also evaluated using bisphosphonate-immobilized titanium. X-ray photoelectron spectroscopy analysis suggested that titanium surfaces modified with Ca-ion implantation and thin hydroxyapatite coatings caused the immobilization of bisphosphonate on titanium plates. The ALP activity of osteoblastic cells cultured on plates immobilized with bisphosphonate was almost the same as that of cells cultured on titanium plates, indicating that the bisphosphonate-immobilization showed no toxic effect on osteoblastic cells, and that it provides a favorable micro-environment with osteogenetic ability. Data of the adherence of oral bacteria showed that a bisphosphonate-immobilized titanium surface inhibited the initial adherence of P. gingivalis. These results indicate that the immobilization of bisphosphonates on titanium modified with Ca-ion implantation and thin hydroxyapatite coatings are useful for dental implants.

Animals↗
PubMed2001

Influence of surface modifications to titanium on antibacterial activity in vitro.

The antibacterial effect of surface modifications to titanium on Porphyromonas gingivalis ATCC 33277 and Actinobacillus actinomycetemcomitans ATCC 43718 was evaluated. Surface modifications were performed with dry processes including ion implantation (Ca+, N+, F+), oxidation (anode oxidation, titania spraying), ion plating (TiN, alumina), and ion beam mixing (Ag, Sn, Zn, Pt) with Ar+ on polished pure titanium plates. F+-implanted specimens significantly inhibited the growth of both P. gingivalis and A. actinomycetemcomitans than the polished titanium. The other surface-modified specimens did not exhibit effective antibacterial activity against both bacteria. No release of the fluorine ion was detected from F-implanted specimens under dissolution testing. This result and the characterization of the F+-implanted surfaces suggested that the possible antibacterial mechanism of the F+-implanted specimen was caused by the formation of a metal fluoride complex on the surfaces. In addition, F+-implanted surfaces did not inhibit the proliferation of fibroblast L929-cells. These findings indicate that surface modification by means of a dry process is useful in providing antibacterial activity of oral bacteria to titanium implants exposed to the oral cavity.

Aggregatibacter actinomycetemcomitans↗
PubMed2001

Substrate affects the initial attachment and subsequent behavior of human osteoblastic cells (Saos-2).

Interaction between implant materials and bone cells contributes to the clinical success of dental implants. The object of this study was to investigate the initial attachment and subsequent behavior of human osteoblastic cells (Saos-2) to pure titanium (Ti), hydroxyapatite (HA), and glass. We, therefore, performed a time-course study for examining the area, attachment rate, distribution of focal adhesion kinase (FAK) vinculin, and actin, and the motility of Saos-2 cells on the materials. On Ti, cell area increased gradually, whereas on HA, cells spread quickly, but quitted spreading at 12 h after cell seeding. The number of cells on HA was greater than on the other materials. On Ti, the numbers of FAK- and vinculin-positive focal adhesions increased continuously. On HA, although the number of FAK-positive focal adhesions also increased continuously, the number of vinculin-positive focal adhesions decreased. Furthermore, actin staining showed that the cells on HA poorly formed stress fibers with weak polarity, whereas the cell on Ti possessed well-defined polarized stress fibers. On HA, cells started extension earlier than on Ti, motility was inactive, and the cells settled on the materials. These results suggest that the earlier settling of osteoblasts on HA might result in earlier osteogenesis on HA than other materials.

Actins↗
PubMed2001

Pancreatic islet blood flow in conscious rats during hyperglycemia and hypoglycemia.

Anesthesia affects general hemodynamics and regulation of organ perfusion. We used colored microspheres to measure pancreatic islet blood flow in conscious rats at two time points, during either hyperglycemia or hypoglycemia. This method, using black and green microspheres, was validated by comparison with previous microsphere experiments and by lack of effect of a nonmetabolizable glucose analog, 3-O-methylglucose, on islet perfusion. Basal and glucose-stimulated islet blood flow levels were similar in pentobarbital sodium-anesthetized and conscious rats. However, the basal distribution of pancreatic blood flow was altered by anesthesia (fractional islet blood flow 5.8 +/- 0.4% in conscious rats, 7.9 +/- 0.8% in pentobarbital-anesthetized rats, P < 0.05). Insulin-induced hypoglycemia significantly increased whole pancreatic blood flow in conscious rats, whereas islet blood flow remained unchanged and fractional islet blood flow was decreased (5.8 +/- 0.5% in the basal state, 4.2 +/- 0.4% during hypoglycemia, P < 0.001). Methylatropine pretreatment significantly increased islet blood flow during hypoglycemia by 181%. This result suggests that prevention of hypoglycemia-induced increase in islet perfusion may be mediated, at least in part, by a cholinergic, vagal muscarinic mechanism.

3-O-Methylglucose↗
PubMed2001

Monitoring of minimal residual disease in children with acute promyelocytic leukemia by RT-PCR detecting PML/RARalpha chimeric gene: a retrospective study of clinical feasibility.

We studied retrospectively the clinical feasibility of minimal residual disease (MRD) monitoring by reverse transcription-polymerase chain reaction (RT-PCR) detecting the PML/retinoic acid receptor alpha (RARalpha) chimeric gene in children with acute promyelocytic leukemia (APL). MRD monitoring of APL was performed with standard and nested RT-PCR for PML/RARalpha gene, the sensitivity of which was 1 leukemic cell in 10(3)-10(4) and 1 in 10(4)-10(5) cells, respectively. Patients were nine children with APL (average age: 8.3 year; average period of follow-up: 69.2 months) who, after achieving remission with all-trans retinoic acid (ATRA), received treatment either with multidrug chemotherapy or with a combination of chemotherapy and ATRA. Out of six patients treated with multidrug-combined chemotherapy, two patients exhibited PCR positivity after six months of post- remission therapy, which shifted from the detectable range of the nested PCR to that of the standard PCR. These two patients subsequently relapsed and, together with two of the other patients receiving multidrug-combined chemotherapy, underwent allogeneic bone marrow transplantation. No MRD was detected in these patients after transplantation. In the remaining three patients who underwent cyclic treatment with alternative chemotherapy and ATRA, two showed positive RT-PCR at the nested or standard level, respectively, after six months of combined therapy, and one of them relapsed. Overall, three of four patients with MRD detected in post-remission period ultimately relapsed, while all of five patients without detectable MRD had a good prognosis. These findings suggest that impending relapse may be predicted by the detection of preceding PCR positivity with an increasing quantity of the PML/RARalpha mRNA that appears beyond six months of post-remission chemotherapy, with or without combined ATRA therapy.

Adolescent↗
PubMed2001

Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.

The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases.

Aluminum↗
PubMed2001

Orthostatic hypertension in patients with type 2 diabetes.

OBJECTIVE: The prevalence and clinical importance of orthostatic hypertension (OHT) in diabetic patients has not been elucidated, in contrast to orthostatic hypotension, which is occasionally found in diabetic patients with autonomic neuropathy. RESEARCH DESIGN AND METHODS: The prevalence and severity of orthostatic hypertension was investigated in 277 Japanese male patients with type 2 diabetes, including 90 hypertensive patients and 128 nondiabetic age-matched male subjects. Patients treated with antihypertensive drugs were excluded from the study. OHT was defined as an increase in diastolic blood pressure (DBP) from <90 to >or=90 mmHg and/or an increase in systolic blood pressure (SBP) from <140 to >or=140 mmHg after standing from supine position. Clinical profiles and several serum biochemical parameters were determined in addition to chest X-rays and electrocardiograms. RESULTS: The prevalence of OHT in normotensive and hypertensive diabetic patients was significantly higher than in control subjects (12.8 vs. 1.8%, P < 0.01, for normotensive patients; 12.6 vs. 11.1%, not significant, for hypertensive patients). Orthostasis induced a mean increase of 6.8 +/- 11.4 mmHg in SBP and 9.1 +/- 5.2 mmHg in DBP in diabetic patients with OHT compared with those without OHT (-1.0 +/- 9.0 and 3.8 +/- 6.6 mmHg, respectively). Vibration sensation in the lower limb was reduced in diabetic patients with OHT, but the percent coefficient of variation of RR interval, cardio-to-thoracic ratio on chest X-ray, and serum triglyceride levels were higher in these patients compared with normotensive diabetic patients without OHT. CONCLUSIONS: Orthostatic hypertension is a novel complication in normotensive diabetic patients and may associate with early stage neuropathy and development of sustained hypertension.

Diabetes Mellitus, Type 2↗
PubMed2001

Casting accuracy of experimental Ti-Cu alloys.

The purpose of the present study was to investigate the casting accuracy and the dimensional change of experimental titanium-copper alloys (3.0 and 5.0 mass% Cu; hereafter, only "%" will be used) and to compare the findings with those of pure titanium. Castings were made using an argon-arc melting/pressure difference-casting unit. The fit of the metals cast in both full crown and MOD inlay dies was evaluated by measuring the distance between the shoulder margin and the cervical shoulder of the die. The changes in the inner diameter of castings were determined. In addition, surface roughness measurements inside the castings were carried out using a conventional profilometer, and thermal expansion measurements were made on cast cylindrical specimens using a differential dilatometer. There were no significant differences in dimensional change between pure titanium and the titanium-copper alloys. The fit of the titanium-copper alloys was inferior to pure titanium. The results of surface roughness measurements showed significance differences between the roughness of the pure titanium and titanium-copper alloys.

Analysis of Variance↗
PubMed2000

Nuclear transfer in cattle using colostrum-derived mammary gland epithelial cells and ear-derived fibroblast cells.

To assess the developmental potential of nuclear transfer embryos in cattle using mammary gland epithelial (MGE) cells derived from the colostrum, we compared the effectiveness of cloning using those cells and fibroblast cells derived from the ear. The fusion rate of the enucleated oocytes with fibroblast cells (75 +/- 4%) was significantly higher than that with MGE cells (56 +/- 7%, P<0.05). There were no significant differences in the cleavage rate (85 +/- 3% vs. 91+/- 2%) or in the developmental rate to the blastocyst stage (35 +/- 6% vs. 35 +/- 5%) using MGE cells vs. fibroblast cells as donor nuclei (P>0.05). After transfer of blastocysts derived from nuclear transfer embryos produced using MGE cells and fibroblast cells, 13% (4/31) and 16% (6/37) of recipient heifers were pregnant on Day 42 as assessed by ultrasonography, respectively. Two of the 4 and 4 of the 6 recipients of embryos with MGE cell- and fibroblast cell-derived nuclei, respectively, aborted within 150 days of pregnancy. Four live female calves were obtained from MGE cells or fibroblast cells. However, one died from internal hemorrhage of the arteria umbilicalis. The other three calves were normal and healthy. There were no differences in the pregnancy rate or calving rate when using MGE cells vs. fibroblast cells. Microsatellite DNA analyses confirmed that the cloned calves were genetically identical to the donor cows and different from the recipient heifers. We conclude that colostrum-derived MGE cells have the developmental potential to term by nuclear transfer, and the efficiency of development of those cloned embryos was the same as that of embryos obtained using fibroblast cells as donor nuclei, although there was a significant difference in the fusion rate. This method using MGE cells derived from colostrum, which is obtained easily and safely from live adult cows, is more advantageous for cloning with somatic cells.

Animals↗
PubMed2000

Peroxisome proliferator-activated receptor gamma1 (PPARgamma1) expresses in rat mesangial cells and PPARgamma agonists modulate its differentiation.

Thiazolidinediones, synthetic ligands of peroxisome proliferator-activated receptor gamma (PPARgamma), are reported to have direct beneficial effects on diabetic nephropathy without lowering blood glucose levels in human and rat. We hypothesized these effects of thiazolidinediones might be derived from PPARgamma activation of kidney cells, and we examined the expression of PPARgamma and the effect of PPARgamma agonists, troglitazone and 15-deoxy-delta-prostaglandin J2 (15d-PGJ2), on the proliferation and differentiation in rat mesangial cells. A single band of mRNA of PPARgamma with a predicted size was detected in reverse transcription-polymerase chain reaction products (RT-PCR) using established PCR probes of PPARgamma. PPARgamma protein in rat mesangial cells was identified as PPARgamma1 by a Western blot. In a gel mobility shift assay to determine a binding activity of PPARgamma, the nuclear protein from rat mesangial cells bound to a (32)P-labeled oligonucleotide probe, including PPAR response elements. A synthetic and a natural ligand of PPARgamma, troglitazone and 15d-PGJ2, decreased thymidine incorporation in a dose dependent manner. After 7 days incubation with troglitazone and 15d-PGJ2, alpha-smooth muscle actin expression, a marker of mesangial cell de-differentiation, was decreased significantly compared to that of control. These results indicate that PPARgamma1 is expressing in rat mesangial cells, and PPARgamma1 activation with its agonists modulates the proliferation and differentiation of cultured rat mesangial cells.

Animals↗
PubMed2000

In vivo gene gun-mediated DNA delivery into rodent brain tissue.

Various types of gene transfer into live tissues have been tried. However, in vivo gene transfer into brain tissue or neuronal cells without virus vector has required a great effort. Particle-mediated gene transfer into live brain tissue was thought to be impossible because of its fragility and the mechanical problem of a previous type of gene gun. In addition, particle-mediated DNA transfer into monolayer-cultured cells without mechanical damage has been difficult. We successfully transferred DNA into rodent live brain tissue and also into monolayer-cultured cells without mechanical damage by using a new type of gene gun and also confirmed gene expression in the brain. This new method represents another variation of gene transfer into the brain.

Animals↗
PubMed2000

Influence of surface modifications to titanium on oral bacterial adhesion in vitro.

The influence of surface modifications to titanium on the initial adherence of Porphyromonas gingivalis ATCC33277 and Actinobacillus actinomycetemcomitans ATCC43718 was evaluated. Surface modifications were performed with dry processes including ion implantation (Ca(+), N(+), F(+)), oxidation (anode oxidation, titania spraying), ion plating (TiN, alumina), and ion beam mixing (Ag, Sn, Zn, Pt) with Ar(+) on polished pure titanium plates. Comparatively large amounts of P. gingivalis and A. actinomycetemcomitans adhered to polished titanium plates. The degree of P. gingivalis adhesion showed a positive correlation with surface energy and the amount of calcium-ion adsorption. Adherence of both P. gingivalis and A. actinomycetemcomitans increased on calcium-implanted surfaces compared with polished titanium surfaces, whereas adherence of P. gingivalis was remarkably decreased on alumina-coated surfaces. These findings indicate that titanium implants exposed to the oral cavity require surface modification to inhibit the adherence of oral bacteria, and that surface modification with a dry process is useful in controlling the adhesion of oral bacteria as well as ensuring resistance against wear.

Aggregatibacter actinomycetemcomitans↗
PubMed2000

Impaired expression of MHC class I molecules on mouse testicular germ cells is mainly caused by the post-transcriptional mechanism.

In this study, we examined expression of the major histocompatibility complex (MHC) class I molecules and of the mRNAs for MHC class I-mediated antigen presentation machinery molecules in highly purified C57BL/6 mouse testicular germ cells. Although H2 class I molecules were not detected on the cell surface, small amounts of the molecules were detected inside the cells by flow cytometric and immunoprecipitation analyses. Interferon (IFN)gamma treatment did not affect expression of the molecules on the surface by flow cytometric analysis. In addition, expression of mRNAs for MHC class I-mediated antigen presentation machinery molecules in the germ cells was analyzed by reverse transcription-polymerase chain reaction analysis. The faint constitutive expression of mRNAs for H2-K, beta2-microglobulin (beta2m), tapasin, and calnexin was observed in the cells. IFNgamma treatment up-regulated expression of mRNAs for H2-K, beta2m, TAP1 (a peptide transporter), and LMP2 (a proteosomal subunit). These findings indicate that impaired expression of MHC class I molecules on the cell surface of mouse testicular germ cells is mainly caused by the post-transcriptional regulatory mechanism.

Animals↗