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T Shibuya

Publications and source records attributed to T Shibuya.

At least 19 recordsLinked to original sources
PubMed1996

Dose-dependent induction of recessive mutations with N-ethyl-N-nitrosourea in primordial germ cells of male mice.

Using a specific locus test, we previously found that N-ethyl-N-nitrosourea (ENU) induces recessive mutations at a relatively high rate in male mouse primordial germ cells (PGC) at 8.5, 10.5 and 13.5 days of development (G8.5, G10.5 and G13.5). A large difference was observed on the induced mutation rate between 30 and 50 mg/kg ENU in 10.5-day PGC. We therefore carried out specific locus tests to ascertain whether ENU induces recessive mutations in a dose-dependent manner in G8.5 and G10.5 PGC. We also gave multiple doses of 25 mg/kg ENU using an 18-h interval, the approximate doubling time of PGC at these developmental stages, to test for an additive effect on the induced mutations rate. A dose-dependent induction of recessive mutations by ENU was observed in both G8.5 and G10.5 PGC, and multiple dosing of 25 mg/kg ENU showed an additive effect. Comparing these results to data on spermatogonial stem cells, we conclude the capacity to repair ENU-induced premutagenic damages is less effective in male mouse PGC at these developmental stages than in spermatogonial stem cells.

Animals↗
PubMed1996

Hemostasis activation during sclerotherapy of lower extremity varices.

The influence of compression sclerotherapy upon hemostasis activation was investigated in 41 consecutive patients with lower extremity varices by serial measurement of thrombin-antithrombin III complexes (TAT), D-dimer, fibrinogen and C-reactive protein (CRP). Blood sampling was carried out before operation and on the 7th and 28th post-operative day in patients randomly assigned to either the control group (n = 18), in which high ligation of sapheno-femoral junction and local excision of varices were performed, or the sclerotherapy group (n = 23) in which the comparable surgical intervention and compression sclerotherapy using hypertonic saline were performed simultaneously. In both groups, the TAT, D-dimer and fibrinogen concentrations at day 7 were significantly elevated compared to the value before operation while CRP showed no significant change during the observation period. In the sclerotherapy group, higher incidence of superficial thrombosis was observed and the TAT concentration at day 7 was significantly higher than that in the control group (p < 0.01), and the TAT at day 28 was still significantly elevated compared to the pre-operative level (p < 0.05). However, no relationship between TAT and D-dimer concentrations and the extent of superficial thrombosis was observed. We conclude that compression sclerotherapy for lower extremity varices causes latent activation of coagulation system and can be a risk factor for venous thromboembolism.

Antithrombin III↗
PubMed1996

Mechanical and biological properties of two types of bioactive bone cements containing MgO-CaO-SiO2-P2O5-CaF2 glass and glass-ceramic powder.

In this study two types of bioactive bone cement containing either MgO-CaO-SiO2-P2O5-CaF2 glass (type A) or glass-ceramic powder (type B) were made to evaluate the effect of the crystalline phases on their mechanical and biological properties. Type A bone cement was produced from glass powder and bisphenol-a-glycidyl methacrylate (BIS-GMA) resin, and type B from glass-ceramic powder containing apatite and wollastonite crystals and BIS-GMA resin. Glass or glass-ceramic powder (30, 50, 70, and 80 by wt %) was added to the cement. The compressive strength of type A (153-180 MPa) and B (167-194 MPa) cement were more than twice that of conventional polymethylmethacrylate (PMMA) cement (68 MPa). Histological examination of rat tibiae showed that all the bioactive cements formed direct contact with the bone. A reactive layer was seen at the bone-cement interface. In specimens with type A cement the reactive layer consisted of two layers, a radiopaque outer layer (Ca-P-rich layer) and a relatively radiolucent inner layer (low-calcium-level layer). With type B cement, although the Ca-P-rich layer was seen, the radiolucent inner layer was absent. Up to 26 weeks there was progressive bone formation around each cement (70 wt %) and no evidence of biodegradation. The mechanical and biological properties of the cements were compared with those of a previously reported bone cement containing MgO-free CaO-SiO2-P2O5-CaF2 glass powder (designated type C).

Animals↗
PubMed1996

Bone bonding behavior of titanium and its alloys when coated with titanium oxide (TiO2) and titanium silicate (Ti5Si3).

It has been proposed that the essential requirement for artificial materials to bond to living bone is the formation of bonelike apatite on their surfaces in the body. Recent studies have shown that titanium hydrogel and silica gel induce apatite formation on their surface in a simulated body fluid. In this study, the influence of titanium oxide and titanium silicate on the bonding of titanium alloys to bone was studied. Rectangular implants (15 x 10 x 2.2 mm) of titanium, Ti-6Al-4V, Ti-6Al-2Nb-Ta, Ti-6Al-4V coated with TiO2, and Ti-6Al-4V coated with Ti5Si3 were implanted into the tibial metaphyses of mature rabbits. At 8 and 24 weeks after implantation, the tibiae containing the implants were dissected out and subjected to a detaching testing. The failure load for titanium, Ti-6Al-4V, Ti-6Al-2Nb-Ta, Ti-6Al-4V coated with TiO2, and Ti-6Al-4V coated with Ti5Si3 were, respectively, 0.68 +/- 0.48, 0.22 +/- 0.46, 0.67 +/- 0.59, 2.18 +/- 0.71 and 2.03 +/- 0.41 kgf at 8 weeks, and 2.7 +/- 0.91, 2.58 +/- 1.29, 2.38 +/- 0.41, 3.79 +/- 1.7, and 2.79 +/- 0.87 kgf at 24 weeks after implantation. Histological examination by Giemsa surface staining, CMR, and SEM-EPMA revealed the coated titanium alloy implants directly bonded to bone tissue during early implantation. A Ca-P layer was observed at the interface of the coated implants and the bone. The results of this study indicated that TiO2 and Ti5Si3 can enhance the early bonding of titanium alloys to bone by inducing a Ca-P layer (chemical apatite) on the surface of titanium alloys. It also is suggested that the direct bone contact occurs in relation to the calcium and phosphorus adsorption onto the surface of the titanium passive layer formed during long-term implantation.

Alloys↗
PubMed1996

Osteogenic differentiation of cultured marrow stromal stem cells on the surface of bioactive glass ceramics.

To investigate the significance of apatite-wollastonite-containing glass ceramic (AW ceramic) surfaces and the biological apatite layer formed on these surfaces, rat marrow cell culture, which shows osteogenic differentiation, was carried out on four different culture substrata (control culture dish, two AW ceramics, each having a different surface roughness, and a ceramic on which an apatite layer was formed. A culture period of 2 weeks in the presence of beta-glycerophosphate, ascorbic acid, and dexamethasone resulted in abundant mineralized nodule formations that were positive for alkaline phosphatase (ALP) stain on all substrata. The stain on the apatite-formed AW ceramic was the most intense, the enzyme activity being about twice that of the control culture dish, which had the lowest stain and activity of the four substrata. Northern blot analysis of bone Gla protein (BGP) showed the same tendency, that is, the amount of BGP mRNA from cultured cells on the apatite-formed AW ceramics was the highest and the mRNA on the control dish was the lowest. These data indicate that the glass ceramic surface promotes osteoblastic differentiation and that the promotion can be further enhanced by the formation of a biological apatite layer on the ceramic surface.

Alkaline Phosphatase↗
PubMed1996

Testicular development and fertility of mice treated prenatally with N-nitroso-N-ethylurea at various gestational stages.

N-nitroso-N-ethylurea (ENU) was injected intraperitoneally (i.p.) into ICR female mice at 50 mg/kg on day 8, 10, 12, or 16 of gestation (plug day = day 0). Male newborns treated prenatally with ENU were obtained. Body and testes weights of males were measured on postnatal days 4, 12, and 21 and at 12 weeks of age, as well as histopathological observation of their testes. The treated males were mated at 10 weeks to untreated females of the same strain. Subsequently, the plasma testosterone concentration in each group was determined by enzyme immunoassay. Body weight on postnatal day 4 in the group treated on day 16 of gestation was significantly lower compared to that of the control group. On postnatal day 21 and at 12 weeks of age, body weight was significantly lower in all groups treated with ENU compared to that of the control group. Among the embryonic stages tested, embryonic day 10 is the most susceptible to ENU insult with respect to the postnatal development of testes and epididymides, when judged by the relative weight at 12 weeks of age. The fertility of the male offspring was drastically impaired by the prenatal ENU treatment on embryonic day 10, followed by day 12, while the fertility of male offspring treated on embryonic days 8 and 16 was not affected. Histopathological sections of testes of male offspring treated with ENU on embryonic day 10 resulted in the most severe changes in the seminiferous tubules. The plasma testosterone concentration was drastically lower in male offspring treated on embryonic day 10 compared to the control level. These results demonstrate that the impaired fertility of the ENU-affected mice was the result of paucity of germ cells and that the critical period in the male mouse fetus with respect to the disturbance of postnatal testicular development and fertility was around embryonic day 10, which is the period of primordial germ cell migration.

Abnormalities, Drug-Induced↗
PubMed1996

Pseudointimal hyperplasia of ridged outer wall polytetrafluoroethylene vascular prostheses.

In addition to the polytetrafluoroethylene (PTFE) vascular graft (G) with its conventionally smooth surface, a unique PTFE graft with a ridged outer wall (T) is now also currently available for clinical use. Although an excellent antikinking property is provided by this unique outer structure, the possible influence of the structure on the formation of pseudointima has not yet been investigated in detail. Four kinds of T grafts (3 mm inner diameter, 3 cm long) with various fibril lengths (FL, T-15, T-30, T-60, T-90) and a G graft with 30 microns FL (G-30) were implanted into the inferior vena cava of rabbits. The patency of the grafts at 4 weeks were as follows: 6/8(T-15), 6/8(T-30), 5/8(T-60), 0/8(T-90) and 4/6 (G-30). Pseudointimal hyperplasia (PH) of the T grafts advanced as the FL increased, judging by the thickness of the pseudointima, cellular density, and maturity of fibroblasts. In addition, the maturity of endothelial-like cells on the luminal surface increased as the FL increased. The degree of pseudointimal hyperplasia in G-30 was comparable to that of T-15, although the maturity of the endothelial-like cells was similar to that of T-60. Microscopically, there was a micro-heterogeneity of cellular density in T grafts probably due to the uneven outer structure. In conclusion, not only FL but also the outer structure of PTFE may thus influence the formation of the pseudointima.

Animals↗
PubMed1996

Inducible osteonecrosis in a rabbit serum sickness model: deposition of immune complexes in bone marrow.

We established inducible osteonecrosis in a rabbit serum sickness model. Osteonecrosis with marrow necrosis could be induced by the intravenous injection of horse serum in two doses separated in time by a period of three weeks. In this model, osteonecrosis could be successfully produced in rabbit femoral metaphysis. The incidence of marrow necrosis was 45% (9 of 20 rabbits) and trabecular necrosis occurred in 6 of 20 rabbits (30%) at 7 days after the second injection of the horse serum. In bone marrow of the femoral metaphysis, extravasation of erythrocytes and the formation of micro-thrombi in arterioles were often observed in an early stage of the present model and both findings correlate well each other (p = 0.0001). Immune complexes could be demonstrated using immunohistochemistry in bone marrow of the femoral metaphysis as well as in glomeruli of the kidney. Extravasation of erythrocytes in bone marrow of the femoral metaphysis was observed in 8 of 12 (67%) cases with immune complex deposition in the sinusoidal space of the femoral metaphysis and in 12 of 21 (57%) cases with immune complex deposition in glomeruli of the kidney. Immune complex deposition both in the sinusoidal space of femoral bone marrow (p = 0.0385) and in glomeruli of the kidney (p = 0.0209) closely related to extravasation of erythrocytes and microthrombi in arterioles in the early stage of this model. Early microcirculatory injury (extravasation of erythrocytes and microthrombi in arterioles) adjacent to osteonecrosis could be induced by immune complex deposition in femoral bone marrow and might be predictable characteristics for the inducible osteonecrosis in the present serum sickness model. The important findings in this study were that early microcirculatory injury was closely related to the deposition of immune complexes in femoral bone marrow, and that early microcirculatory injury associated with immune complex deposition was located close to osteonecrotic regions.

Animals↗
PubMed1996

Uncoupling mechanism of glycoside antibiotic aculeximycin in isolated rat-liver mitochondria.

Effects of basic glycoside antibiotic aculeximycin (ACM) on the oxidative phosphorylation of rat-liver mitochondria were examined. ACM was shown to be a potent uncoupler of the oxidative phosphorylation. To cause the same extent of respiration release, higher concentration of ACM was required in phosphate (Pi)-free medium than in Pi medium. During the uncoupling caused by ACM in Pi medium, large amplitude swelling and oxidation of intramitochondrial NAD(P)H occurred, indicating that ACM remarkably enhances permeability of the inner mitochondrial membrane. The Pi uptake via Pi/H+ symporter was shown to play an important, but not essential, role in the uncoupling by ACM, indicating the increase in membrane permeability is mostly due to acceleration of Pi/H+ influx through Pi/H+ symporter activated by ACM. ACM is the first naturally occurring antibiotic, to our knowledge, which activates Pi/H+ symporter. However, since the inhibition of Pi/H+ symporter by N-ethylmaleimide did not completely abolish the uncoupling activity of ACM, and ACM induced the uncoupling even in Pi-free medium, an increase in the membrane permeability for other ions, such as Na+ and K+, due to a different action mechanism has also to be considered. On the other hand, positively charged amine local anesthetics, like dibucaine, prevented the uncoupling activity by ACM in both Pi and Pi-free medium. The uncoupling activity of N-diacetylated ACM lacking free amino groups was ca. 1/120th that of ACM, indicating that positively charged amino groups are important for the uncoupling activity. It is suggested that some specific interactions between positively charged amino groups of ACM and the binding site, which is probably negatively charged, are triggers that affect the permeability of the inner mitochondrial membrane. Amine local anesthetics may mask the negative charge of the binding site, thereby interfering with ACM binding.

Animals↗
PubMed1996

[A case of schistosomiasis suspected by circumoval precipitin test and diagnosed by rectal biopsy].

A forty-year-old female from Brazil was admitted to Teikyo Hospital because of easy fatigability, fullness of the abdomen and left hyochondralgia. She was anxious about Schistosoma mansoni infection, because three of her relatives died of the infection. Physical examinations revealed a tenderness at the left hypochondrium. Laboratory data showed no abnormal finding. No egg of S. mansoni was found in the stool. A circumoval precipitin test (COPT) with the serum showed a deposite around the egg. Enzyme-linked immunosorbent assay (ELISA) revealed the presence of antibody against S. mansoni in the serum. A colonoscopy showed no abnormal finding macroscopically. The rectal biopsy showed the existence of mild procitis. The diagnosis was made by finding the characteristic lateral-spined eggs in the biopsy specimens from the rectum. Treatment of 3 g of prazicantel per day for three days was started. She complained of mild nausea at the first dosing. A month later, another three-day-treatment was given. In the case where there are no eggs found in the stool, COPT and ELISA are usefull in detecting the disease, and colonoscopy is recommended in diagnosing the disease.

Adult↗
PubMed1996

Electron microscopic observation of eosinophils migrated to the thoracic cavity of Litomosoides carinii-infected mice.

In order to study the role of eosinophils in filarial infection, ddY mice were inoculated with 20 Litomosoides carinii 7-day larvae each by the artificial pneumothorax technique. Migrated cells and larvae were collected from the thoracic cavity of the infected mice weekly from the 1st to the 8th week after infection and prepared for transmission electron microscopic observation. The number of migrated eosinophils and the proportion of eosinophils in the total migrated cells reached a peak at the 5th week. At the same time, eosinophils with low density granules were observed in both unattached and attached cells. In particular, many attached eosinophils with low density granules were observed directly on the worm surface. These observations strongly suggest that eosinophils are associated with attack on filarial worms.

Animals↗
PubMed1996

Cytomegalovirus-induced interstitial pneumonitis in a patient with systemic lupus erythematosus.

We report an unusual case of cytomegalovirus (CMV) interstitial pneumonitis (IP) occurring in a 51-year-old Japanese woman with systemic lupus erythematosus (SLE). She developed hypoxemia after intensive immunosuppressive therapy with prednisolone and cyclophosphamide. Fine crackles were audible in the lower lungs bilaterally. Chest X-ray and computed tomography confirmed the presence of IP. CMV-antigenemia was confirmed by immunological staining of leukocytes using the peroxidase-labeled monoclonal antibody, HRP-C7. Hypoxemia improved gradually on methylprednisolone pulse therapy and gancyclovir, and CMV-antigen positive leukocytes disappeared from the peripheral blood. Data suggest the importance of CMV as a cause of IP in SLE, and the usefulness of the assay for CMV-antigenemia with C7-HRP for rapid diagnosis.

Antigens, Viral↗
PubMed1996

[Analysis of the proliferative potential of meningiomas with MIB-1 monoclonal antibodies].

Tumor recurrence was observed in 12 (11.3%) out of 106 cases of intracranial meningioma followed for more than 5 years. Proliferative potential was evaluated immunohistochemically with MIB-1 monoclonal antibodies in 37 cases of non-recurrent meningioma and 12 cases (21 samples) of recurrent meningioma. The proliferating cell index (PCI) was much higher in the non-recurrent meningiomas than the recurrent meningiomas (10.6 +/- 7.7 [mean +/- SD] versus 1.9 +/- 1.5). Most recurrent meningiomas had high PCI values, greater than 3%. High PCI values of more than 5% were found in 13 (62%) of the 21 samples of recurrent meningioma. However, only 4 of the 37 cases of nonrecurrent meningioma had high PCI values with MIB-1 of more than 3%. The 12 cases of recurrent meningioma were classified into 3 groups: 6 cases in which both the initial and recurrent meningiomas were benign (Group I), 5 cases in which the meningioma at the time of the initial operation was benign, but the recurrent meningioma was malignant (Group II), and one case in which malignant meningioma was diagnosed at the time of the initial operation (Group III). The PCI values with MIB-1 in most of the recurrent meningiomas were higher at the time of recurrence than at the time of the initial operation. Malignant meningiomas, such as anaplastic and atypical meningioma, and some meningotheliomatous meningiomas among the benign meningiomas recurred and had higher PCI with MIB-1 values than other meningiomas. It is concluded that PCI with MIB-1 is important as a predictive factor for the recurrence of meningiomas. Meningiomas having a PCI value with MIB-1 of more than 3% in particular should be followed carefully.

Antibodies, Monoclonal↗
PubMed1995

Functional expression of Fas antigen (CD95) on hematopoietic progenitor cells.

We investigated the expression of an apoptosis-associated antigen (Fas) (CD95) on hematopoietic progenitor cells in the presence or absence of interferon-gamma (IFN-gamma) and/or tumor necrosis factor-alpha (TNF-alpha). CD34+ cells freshly isolated from bone marrow did not express Fas. However, IFN-gamma and/or TNF-alpha induced the expression of both the mRNA of Fas and Fas itself in a dose-dependent fashion on the surface of CD34+ cells after 48 hours of serum-free culture. IFN-gamma and TNF-alpha had a synergistic effect on the induction of Fas, when both cytokines were added to the culture. The TNF-alpha-induced Fas expression is mediated by p55 TNF-alpha receptor. CD34+ cells cultured in medium alone or with stem cell factor (SCF) showed some slight expression of Fas. When anti-Fas antibody (IgM) was added to CD34+ cells after the induction of Fas expression, CD34+ cells underwent apoptosis, as shown by a decrease in the number of viable cells, morphologic changes, the induction of DNA fragmentation, and a decrease in the number of colony-forming cells (CFC) including colony-forming unit granulocytes/macrophages (CFU-GM) and burst-forming unit erythroids (BFU-E). These observations indicate that IFN-gamma and/or TNF-alpha, well known as negative hematopoietic regulators, induce functional Fas on hematopoietic progenitor cells. The suppression of hematopoiesis by negative hematopoietic regulators may be mediated in part by Fas induction.

Antigens, Surface↗
PubMed1995

Involvement of nitric oxide in intracerebroventricular beta-endorphin-induced neuronal release of methionine-enkephalin.

Previous work has suggested that the antinociceptive effect of nitrous oxide (N2O) in rats is mediated, at least in part, by beta-endorphin (beta-EP) and that centrally administered beta-EP stimulates release of methionine-enkephalin (ME) in the rat spinal cord. Since inhibition of central nitric oxide (NO) production has been found to suppress N2O antinociception, we examined the possible involvement of NO in the release of spinal cord ME by i.c.v. beta-EP. Urethane-anesthetized, male Sprague-Dawley rats were intrathecally (i.t.) perfused with artificial cerebrospinal fluid (aCSF) and fractions of perfusate were assayed for immunoreactive (i.r.) ME. The beta-EP-induced increase in ME concentration in the i.t. perfusate was significantly suppressed by perfusing the animal with aCSF containing 100 microM L-NG-nitro arginine (L-NOARG), an inhibitor of NO synthase (NOS). The further addition of 50 microM L-arginine (L-ARG), but not D-arginine (D-ARG), to the aCSF reversed the suppression of the ME change by L-NOARG. However, the potency of L-ARG decreased with increasing concentrations of L-ARG. On the other hand, increasing the concentration of L-NOARG in the aCSF to 250 microM failed to produce a greater suppression of the beta-EP-induced increase in ME. These findings suggest that NO may mediate the beta-EP-induced release of ME in the spinal cord and that interference with this mechanism might be an explanation for the antagonism of N2O antinociception in rats by NOS inhibitors.

Animals↗
PubMed1995

Bioactive bone cement: the effect of amounts of glass powder and histologic changes with time.

A study was conducted to examine the influence of the amount of glass powder added to a bioactive bone cement of our formula on its mechanical and biologic properties. Serial changes in the cement with time were also examined. The bioactive bone cement consisted of CaO-SiO2-P2O5-CaF2 glass powder and bisphenol-a-glycidyl methacrylate resin. Glass powder was added to the cement in 30, 50, 70, and 80% weight ratios. The compressive strengths of the resulting cements (171-239 MPa) were more than double that of polymethylmethacrylate cement (68 MPa). Histologic examination of rat tibiae bearing artificial defects packed with each bioactive cement showed direct bone contact 4 weeks after surgery. The cement with a higher percentage of glass powder showed better direct formation of bone around its periphery with a thicker reactive layer. Under scanning electron microscopic observation, the reactive layer showed increased levels of calcium and phosphorus. Examination of histologic changes up to 26 weeks showed progressive bone formation around the cement and no sign of biodegradation.

Animals↗