Biomedical subjects

H Tamura

Publications and source records attributed to H Tamura.

At least 73 records · Page 4Linked to original sources

PubMed2000

Solubilized cell wall beta-glucan, CSBG, is an epitope of Candida immune mice.

Antibody to beta-glucan is generally difficult to produce in mice. We have recently developed a protocol to obtain a soluble Candida spp. beta-(1-->3)-D-glucan (CSBG) by sodium hypochlorite (NaClO) oxidation and subsequent dimethyl sulfoxide (Me2SO) extraction. CSBG is composed mainly of beta-(1-->3) and beta-(1-->6)-glucosidic linkages with a small amount of branch. In this paper, mice were immunized with Candida albicans and the specificity of the resulting sera to CSBG was examined by ELISA. Using CSBG coated plate, sera of the Candida immune mice showed higher reactivity than non-immune, normal mice and the reactivity was neutralized by adding soluble CSBG as a competitor. However, the reactivity could not be neutralized by a beta-(1-->6) branched beta-(1-->3)-glucan, grifolan. Similar specificity of the sera was obtained by commercially available beta-glucan particle, zymosan or zymocel, immune mice. These facts strongly suggested that CSBG included epitopes of the specific antibody in Candida immune mice.

Animals↗

PubMed2000

Inhibitory effects of green tea and grape juice on the phenol sulfotransferase activity of mouse intestines and human colon carcinoma cell line, Caco-2.

Tea and fruit juices are beverages consumed daily all over the world. The present study reports the inhibitory effects of these beverages on the activity of mammalian intestinal phenol sulfotransferases (P-STs). Green tea strongly inhibited the E. coli-expressed mouse intestinal P-ST activity in vitro. (-)-Epigallocatechin gallate (EGCG) was found to be the most potent inhibitor among the catechins tested (IC50=0.93 microM). (-)EGCG also inhibited the P-ST activity of the human colon carcinoma cell line, Caco-2. Kinetic analysis showed that the inhibition was competitive. Among fruit juices examined (apple, grape, grapefruit and orange), grape juice exhibited the most potent inhibitory action on the P-ST activity of mouse intestines and human colon carcinoma cells. The inhibitory activity of grape juice was located mainly in the skin and seeds. Flavonols, such as quercetin and kaempferol, inhibited the P-ST activity at low concentrations. These observations suggest the possible inhibition of P-ST activity in human intestines by green tea or grape juice.

Animals↗

PubMed2000

Sulfotransferases in a human colon carcinoma cell line, Caco-2.

We investigated the expression of sulfotransferases (STs) in the human colon carcinoma cell line, Caco-2, which is widely used as a human intestine model for orally administered drugs. By reverse transcription-polymerase chain reaction (RT-PCR), we could detect mRNA expressions of phenol STs (P-ST), hydroxysteroid ST (HS-ST) and estrogen ST (E-ST). Treatment with 1,25-dihydroxyvitamine D3, which induces CYP3A4 expression in Caco-2 cells, did not affect the ST expression of the cells. We detected significant P-ST activity toward 2-naphthol and dopamine in the cell extract. We also observed detectable HS-ST activity toward dehydroepiandrosterone (DHEA), but no E-ST activity toward beta-estradiol was observed in the extract. Analyses by RT-PCR and separation of P-ST activities on ion-exchange column chromatography showed that the thermolabile monoamine phenol sulfotransferase (M-PST) is dominant in Caco-2 cells.

Arylsulfotransferase↗

PubMed2000

Involvement of hepatocyte growth factor on hepatocarcinogenesis induced by peroxisome proliferators.

Hepatocyte growth factor (HGF) has been known to enhance the growth of normal hepatocytes, but also to inhibit the growth of neoplastic cells. This article examines the involvement of HGF in the hepatocarcinogenesis caused by peroxisome proliferators (PPs). Up to 78 wk after male F-344 rats were orally given (4-chloro-6-[2,3-xylidino]-2-pyrimidinylthio) acetic acid (Wy-14,643), the hepatocarcinomas and (pre)neoplastic nodules in the livers were observed. At that time, the content of HGF and the expression of HGF mRNA in the liver tumors were significantly decreased. These changes were observed also in the liver of rats treated with other PPs, such as dehydroepiandrosterone and di(2-ethylhexyl)phthalate, but were not observed in tumors induced by genotoxic carcinogens (diethylnitrosamine-phenobarbital). In in vivo experiments, the formation of preneoplastic lesions and the tumors caused by Wy-14,643 administration were markedly suppressed by i.v.-injection of HGF in a dose-dependent manner. In the colony assay using (pre)neoplastic cells from livers of Wy-14,643-treated rats, HGF inhibited the colony formation of (pre)neoplastic cells in a dose-dependent manner. These findings may indicate that decreases in hepatic HGF levels are common and specific events induced by PPs, but not by genotoxic carcinogens, and that those changes play an important role in the promotion of neoplastic or preneoplastic cell growth induced by PPs.

Animals↗

PubMed2000

Phosphorylation of 13 kDa nuclear protein in hepatocarcinomas induced by peroxisome proliferators.

Peroxisome proliferators (PPs) are nongenotoxic compounds causing the emergence of hepatocellular carcinoma in rodents, but the mechanisms of the hepatocarcinogenesis have been unclear. The authors examined the changes in phosphorylation of nuclear proteins after treatment with (4-chloro-6-[2,3-xylidino]-2-pyrimidinylthio) acetic acid (Wy-14,643). Wy-14,643 (0.1% w/w in diet) was given orally to male F-344 rats for up to 80 wk. In the hepatocarcinomas induced by Wy-14,643, phosphorylation of 13 kDa nuclear protein (NP 13), which was resistant to alkaline treatment, was significantly increased. NP 13 phosphorylation gradually increased, dependent on treatment period. Furthermore, in the hepatocarcinomas induced by other PP, di(2-ethylhexyl)phthalate, increase in NP13-phosphorylation was also observed. Therefore, NP 13-phosphorylation may relate to development of preneoplastic or neoplastic lesions induced by PPs.

Animals↗

PubMed2000

Primary insertion of implants in the zygomatic bone following subtotal maxillectomy.

A case of maxillary carcinoma treated with primary insertion of Brånemark implants into the zygomatic bone following subtotal maxillectomy is reported. This method has several advantages. First, early detection of postoperative recurrence is easier than with closing the flap. Second, when the implant is inserted into the midfacial region, zygomatic bone can be useful because of thickness. In addition, applying a maxillary prosthesis in the early stages avoids contracture of facial soft tissue. This primary reconstructive method is effective in cases of preserved zygoma after total maxillectomy.

Carcinoma↗

PubMed2000

[Equilibration period for PaO2 following alteration of FIO2 in mechanically ventilated patients].

To determine arterial oxygen tension (PaO2) in mechanically ventilated patients, we repeatedly measured arterial blood gas (ABG) to examine changes in PaO2 until equilibration following alteration of fractional concentrations of oxygen in inspired gas (FIO2). Forty anesthetized patients with normal arterial oxygenation were randomly assigned to one of four groups. Group 1 (n = 10): Arterial blood samples were drawn every one minute during a 15-min period of equilibration after change of FIO2 from 1.0 to 0.21. Then FIO2 was returned to 1.0 and the similar sampling was repeated. Group 2 (n = 10): The protocol was same as in Group 1 except for FIO2 targeted for 0.8 and 0.4. Group 3 (n = 10): Blood sampling was every two minutes during a 14-min period and repeated while FIO2 was altered as in Group 1. Group 4 (n = 10): The protocol was same as in Group 3 except for the target FIO2 similar to Group 2. PaO2 was stabilized in 4 min at earliest and in 6 min at latest after change of FIO2 in every settings of this study. In mechanically ventilated patients with normal arterial oxygenation, PaO2 could be stabilized after a 6-min period of equilibration following alteration of FIO2.

Blood Gas Analysis↗

PubMed2000

[Randomized comparative study of CMF (cyclophosphamide, methotrexate and 5-fluorouracil) and UFT-tamoxifen regimens as adjuvant chemotherapy after surgery for breast cancer: Tochigi Prefectural Study Group for Post-Breast Cancer Adjuvant Chemotherapy].

This prospective randomized study aimed at establishing the optimal postoperative adjuvant chemotherapy regimen for premenopausal n+ breast cancer patients. The treatments were Regimen A, comprising 6 courses of CMF (cyclophosphamide, 100 mg/body on days 1-14; methotrexate, 40 mg/m2 on days 1 and 8; and 5-fluorouracil, 500 mg/m2 on days 1 and 8), and Regimen B, consisting of UFT (300 mg/day) and tamoxifen (30 mg/day) administered orally each day for 2 years. Telephone registration allocated the patients to the treatment groups by the minimization method in relation to the T category, number of n+ lesions and estrogen receptor status. Forty-five patients were registered, and 44 of them were eligible (22 cases each to Regimen A and Regimen B). The principal background factors showed no biases between the groups. The adverse reaction incidence was significantly higher with Regimen A (90.9% vs 22.7%). The 5-year survival rate was 89.8% with Regimen A and 100% with Regimen B, while the 5-year disease-free rates were 64.5% and 76.3%, showing no statistical significance. Regimen B showed a better QOL rating after 6 months of therapy in relation to nausea-vomiting and hair loss, and after 24 months in relation to appetite, sleep, performance status, happiness, anorexia and hair loss.

Adult↗

PubMed2000

[Imaging of perivascular spaces of the brain: MR-clinical correlation].

1. We evaluated the perivascular spaces(PVS) of the intraparenchymal arteries of the brain obtained from MRI, and compared them with the microangiograms of the injected autopsied brains of normal adults. 2. The three dimensional microangiograms revealed 3 types of intraparenchymal arteries: intracortical, subcortical(including arteries of arcuate fibers) and medullary arteries. PVS of those arteries had punctuated or small linear-shaped appearances according to the dimension and level of MR slices. 3. Basic MR findings of normal PVS showed smooth and well-defined round or elliptical configurations up to 3 mm in diameter without a halo in the surrounding tissue, located along the intraparenchymal arteries, and isointense with cerebro-spinal fluid. 4. PVS around the medullary arteries was dilated with age. Definite PVS was found in the lower portion of the basal ganglia in almost all healthy children and relatively young adults, however, it was less frequent in the subcortical white matter of frontal and parietal lobes. In adults over 60 years of age, dilatation of PVS along the medullary arteries was quite common and progressed into the frontal and parietal lobes. 5. Dilatation of PVS around the medullary arteries was prominent and increased with the number of lacunar infarcts. The sclerotic change of medullary arteries was more accelerated in subjects with hypertension.

Adult↗

PubMed2000

Thrombopoietin and myelodysplastic syndromes.

Thrombopoietin (TPO), a major cytokine involved in megakaryocystopoiesis/thrombopoiesis, may be effective for the treatment of thrombocytopenia associated with myelodysplastic syndromes (MDS). We reviewed the available data relating to the therapeutic potential of TPO for MDS and found the following. The endogenous TPO level is elevated in MDS patients, especially in those with refractory anemia (RA). In RA patients, but not in patients with RA with excess blasts (RAEB) or RAEB in transformation (RAEB-t), both the platelet and megakaryocyte counts correlate inversely with the endogenous TPO level. This scenario indicates that the physiological mechanism for regulating the endogenous TPO level is conserved, at least in part, in RA patients. The number of TPO receptors (TPO-R) expressed on platelets and CD41+ and/or CD34+ cells in MDS is reduced to nearly half the number present in normal subjects. This is consistent with the finding that TPO-induced in vitro megakaryocytopoiesis is not uniformly observed in MDS. Meanwhile, in some patients with RAEB, RAEB-t, or chronic myelomonocytic leukemia, blasts have the TPO-R mRNA and probably TPO-R protein. This fact may explain the lack of correlation between the endogenous TPO level and the platelet and megakaryocyte counts in RAEB and RAEB-t and suggests that TPO may induce blast proliferation in some cases. These findings may be of use when designing a clinical trial of TPO for MDS.

Anemia, Refractory↗

PubMed1999

Effect of insulin-like growth factor-I on growth hormone-releasing factor receptor expression in primary rat anterior pituitary cell culture.

We examined the effect of insulin-like growth factor-I (IGF-I) on GH-releasing factor (GRF) receptor expression in the primary rat anterior pituitary cell culture. The levels of GRF receptor mRNA were dose-dependently reduced by IGF-I treatment for 24 h. To clarify whether altered levels of GRF receptor mRNA contribute to GRF receptor concentrations, we examined the GH response to GRF in vitro. There was no difference in basal GH secretion between control and IGF-I pretreated cells, while GRF-stimulated GH secretion in cells pretreated with IGF-I for 24 h was significantly lower than that in control cells. Moreover, specific [125I] Tyr10-human GRF binding to pituitary cells was reduced significantly by IGF-I treatment. These results suggest that IGF-I acts directly on the pituitary and participates in the regulation of GRF receptor expression.

Animals↗

PubMed1999

Protein tyrosine phosphatase zeta/RPTPbeta interacts with PSD-95/SAP90 family.

PTPzeta/RPTPbeta is a proteoglycan-type receptor-like protein tyrosine phosphatase specifically expressed in the brain. Although several ligands of PTPzeta have been identified, proteins interacting with the intracellular region of PTPzeta are still unknown. We performed yeast two-hybrid screening using the intracellular region of PTPzeta as a bait, and found that the C-terminal sequence of PTPzeta binds to the PSD-95/SAP90 family through the second PDZ domain. Immunohistochemical analysis revealed that PTPzeta and PSD-95/SAP90 are similarly distributed in the dendrites of pyramidal neurons of the hippocampus and neocortex. Furthermore, subcellular fractionation experiments indicated that PTPzeta is concentrated in the postsynaptic density fraction. These results suggested that PTPzeta is involved in the regulation of synaptic function as postsynaptic macromolecular complexes with PSD-95/SAP90.

Animals↗

PubMed1999

Mutation induction by N-propyl-N-nitrosourea in eight MutaMouse organs.

As a part of the 2nd Collaborative Study for the Transgenic Mouse Mutation Assay, we studied the organ specificity and the temporal changes in mutant frequency (MF) of the lacZ gene following intraperitoneal injection of 250 mg/kg N-propyl-N-nitrosourea into male MutaMouse. We used a positive selection system and examined eight organs, i.e., bone marrow, liver, kidney, lung, spleen, brain, heart, and testis. The chemical caused a significant increase in MF in all organs except for brain, and the bone marrow was the most sensitive organ, exhibiting a MF on day 7 that was 10 times that of the control. The MF increased from day 7 to day 28 in liver, kidney, and testis, while it decreased in bone marrow. The relationship between the results of this study and the target organs of carcinogenesis, and the cause of the temporal changes in MF, are discussed.

Animals↗

PubMed1999

Chemical and immunochemical characterization of limulus factor G-activating substance of Candida spp.

The limulus test is a well-established method for the diagnosis of both gram (-) sepsis and invasive fungal infection. To diagnose deep-seated fungal infections, a (1-->3)-beta-D-glucan-specific chromogenic kit (Fungitec G test MK) has been developed and applied clinically. It is suggested that the limulus reactive substance was released from the fungi to the blood, however, its chemical properties were not precisely examined in detail because of the limited quantity available. In this study, we used chemically defined liquid medium to culture Candida spp. and collected the water soluble fraction, CAWS. The yield of CAWS was circa 100 mg/l, independent of the strain of Candida. CAWS reacted with limulus factor G (Fungitec G test MK) at concentrations as low as 100 ng/ml. Limulus factor G reactivity of CAWS was sensitive to (1-->3)-beta-glucanase, zymolyase and was, at least in part, bound to ConA-agarose. The ConA-bound fraction also reacted with anti-beta-glucan antibody. CAWS is mainly composed of mannan and (1-->6)-beta-glucan, in addition to protein, assessed by 1H-NMR spectroscopy. CAWS also reacted with typing sera of Candida spp., specific for cell wall mannan. Chemical, immunochemical and biochemical analyses of CAWS strongly suggested that the limulus factor G-activating substance was a mannan-beta-glucan complex, present within the architecture of the yeast cell wall.

Candida↗

PubMed1999

Solubilization of yeast cell-wall beta-(1-->3)-D-glucan by sodium hypochlorite oxidation and dimethyl sulfoxide extraction.

The limulus test is a well-established method for the diagnosis of both Gram-negative sepsis and invasive fungal infection. To diagnose fungal infections, a beta-(1-->3)-D-glucan-specific chromogenic kit (Fungitec G test MK) has been developed and applied clinically. We are concentrating our main efforts on developing a better standard to improve the precision of this method. To this end, we have successfully developed a protocol to obtain a soluble Candida spp. beta-(1-->3)-D-glucan (CSBG) by sodium hypochlorite (NaClO) oxidation and subsequent dimethyl sulfoxide (Me2SO) extraction (yield of 9.6 +/- 4.1%) of acetone-dried whole-cell preparations. The beta-glucan fraction is free from the cell-wall mannan, gives a symmetrical peak by gel filtration, and is soluble in dilute NaOH. The product is composed mainly of beta-(1-->3)- and beta-(1-->6)-D-glucosidic linkages. The specific activity of the beta-glucan is comparable with pachyman when combined with the Fungitec G test as the standard glucan and reacted as low as 10(-11) g/mL.

Candida↗

PubMed1999

Wy-14,643, a peroxisome proliferator, inhibits compensative cell proliferation and hepatocyte growth factor mRNA expression in the rat liver.

Previously, we found that a peroxisome proliferator significantly reduced hepatic and plasma hepatocyte growth factor (HGF) levels in male F-344 rats, and that the growth of preneoplastic or neoplastic cells induced by this peroxisome proliferator was markedly inhibited by HGF. Here, we examined the effects of [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (Wy-14,643), a peroxisome proliferator, on cell proliferation and HGF mRNA levels in the liver of rats after stimulation of compensative cell proliferation. After 2 weeks of treatment with Wy-14,643, hepatic DNA synthesis caused by partial hepatectomy was decreased by 50% compared with untreated controls. DNA synthesis was maintained at the same reduced level for up to 10 weeks. During this period, hepatic HGF mRNA level was also much lower in Wy-14,643-treated rats than untreated controls. Therefore Wy-14,643, a peroxisome proliferator, would inhibit the growth of normal hepatocytes, and then produce an advantageous circumstance for the selective growth of neoplastic or preneoplastic cells.

Animals↗

PubMed1999

The Relationship between Urinary Pyridinoline, Deoxypyridinoline and Bone Metastasis in a Rat Breast Cancer Model.

BACKGROUND: Bone metastasis from breast cancer is often recognized clinically, but there are nonetheless several difficulties in diagnosis. In this study we used an animal model of bone metastasis from breast cancer and clarified the relationship between the urinary Pyd/Cr and Dpd/Cr and the progression of bone metastasis, compared with other bone related markers: serum alkaline phosphatase bone isozyme (ALP-BI), osteocalcin, and calcium. METHODS: The evaluation of bone metastasis was assessed by histological examination of the thoracic and lumbar vertebrae. According to the histological findings 4 weeks after the tumor cell injection, 11 animals were retrospectively divided into 2 subgroups: (1) tumor-bearing rats with bone destruction due to bone metastasis (TBR-BD(+), n = 5), (2) tumor-bearing rats without bone destruction (TBR-BD(-), n =6). These animals were compared to age-matched controls without tumor cell injection (n =6). An additional 5 animals were sacrificed at 2 weeks after the tumor cell injection to evaluate micrometastasis to bone. RESULTS: The values of other markers for bone metastasis in animals with micrometastatic foci in bone marrow did not differ significantly from those of the controls. Pyd/Cr and Dpd/Cr in the TBR-BD(+) group were significantly higher than those of the TBR-BD(-) and the control group (233 +/- 78.3 vs 93.8 +/- 6.5, 98.5 +/- 18.7, 123.1 +/- 35.9 vs 67.9 +/- 6.2, 60.6 +/- 9.8, p< 0.01), while there were no significant differences between TBR-BD(-) and the control. CONCLUSION: Both Pyd/Cr and Dpd/Cr are correlated significantly with the volume of bone metastasis, and are useful for the diagnosis and evaluation of progression of bone metastasis compared with other markers.

Journal Article↗

PubMed1999

Surface Hydroxyl Site Densities on Metal Oxides as a Measure for the Ion-Exchange Capacity.

Hydroxyl groups on metal oxide in water are the sites for ion exchange, and the surface hydroxyl site density on oxides is a measure of the ion-exchange capacity. Here, the Grignard reagent method was applied to determine the surface hydroxyl site density of oxide samples. The results were similar to those reported for different oxides with other methods (dehydration by heating, tritium exchange, crystallographic calculations, etc.), and they are comparable with those calculated from the closest packing of hydroxide ions. A mechanism of hydroxylation is proposed: lattice oxide ions (extremely strong bases) are exposed to aqueous solutions and are neutralized by water to become hydroxide ions. Also, the saturated deprotonation method was applied to hematite, and it was found that all the acid hydroxyl groups on hematite were deprotonated in very high concentrations of alkali solutions ( approximately 5 mol dm-3 NaOH), and from the saturated amount of OH- consumed by deprotonation, the same result as that by the Grignard method was obtained. It is shown that all hydroxyl groups take part in ion exchange and that the unusually small values reported elsewhere with the saturated (de)protonation method may contain errors. Hetero- or homogeneity of hydroxyl groups in contact with water as ion-exchange sites is also discussed. It is suggested that intensely hydrated layers at the oxide/water interface may result in homogeneous discrete sites. The development of microstructures in the oxides was suggested from the measured values of specific surface areas, and the effect of the microstructure environments on the reactivity of internal surface hydroxyl sites is discussed. Copyright 1999 Academic Press.

Journal Article↗