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Biomedical subjects

H Osada

Publications and source records attributed to H Osada.

At least 91 records · Page 5Linked to original sources
PubMed1999

A novel recognition motif of human NKT antigen receptor for a glycolipid ligand.

Murine NKT cells can recognize alpha-galactosylceramide (alpha-GalCer) in the context of a class Ib CD1d molecule. Here we show that alpha-GalCer can selectively activate freshly isolated human Valpha24(+)Vbeta11(+) cells, functionally defining the human NKT cells. The naive human NKT cell repertoire consisted of cells expressing an invariant Valpha24JalphaQ chain and a diverse array of beta chains derived from a single Vbeta11 gene segment. Stimulation with alpha-GalCer expanded a polyclonal subset of the human NKT cell repertoire carrying a novel complementarity-determining region (CDR) 3beta consensus motif that may directly interact with the sugar moiety of alpha-GalCer. Our data suggest that certain redundancy is allowed for CDR3beta of NKT antigen receptor to interact with the ligand and provide a first clue to understand the novel protein-carbohydrate interaction mechanisms.

Adult↗
PubMed1999

Protein phosphatase 2A inhibitors, phoslactomycins. Effects on the cytoskeleton in NIH/3T3 cells.

Protein phosphorylation is a key regulatory mechanism of the organization and dynamics of the actin cytoskeleton during cell motility, differentiation, and cytokinesis. The level of protein phosphorylation is dependent on the relative activities of both protein kinases and protein phosphatases. In this paper, we examined the effect of phoslactomycins (PLMs) on the regulation of the cytoskeleton of NIH/3T3 fibroblasts. Treatment of cells with PLM-F (10 microM) induced actin filament depolymerization after 4 h. This effect was reversible and actin filaments were reformed 1 h after removal of the inhibitors. As PLM-F had no effect at all on polymerization of purified actin in vitro, it is thought that PLMs induce actin depolymerization through an indirect mechanism. An in vitro assay showed PLMs inhibited protein phosphatase 2A at lower concentrations (IC50 4.7 microM) than protein phosphatase 1. An in situ phosphorylation assay also revealed that PLM-F treatment stimulated the phosphorylation of intracellular vimentin. These results suggest that phoslactomycins are protein phosphatase 2A-specific inhibitors and that protein phosphatase 2A is involved in regulation of the organization of the actin cytoskeleton.

3T3 Cells↗
PubMed1999

Low-dose GnRH agonist therapy for the management of endometriosis.

OBJECTIVE: In order to examine whether treatment with a GnRH agonist alone can maintain estrogen levels within the "estrogen window" that inhibits endometriosis without influencing bone-mineral density, we studied the effects of GnRH agonist therapy and changes in bone-mineral density. METHODS: Buserelin acetate nasal spray was administered 3 times a day for 8 weeks (daily dose, 900 micrograms) to 21 women with endometriosis. The drug was then given twice a day for 16 weeks (daily dose, 600 micrograms). The total duration of treatment was 24 weeks. The bone-mineral density of the lumbar vertebrae was measured by dual-energy X-ray absorptiometry before treatment (baseline), at the end of treatment, and 24 weeks after the end of treatment. RESULTS: The bone-mineral density of the lumbar vertebrae at the end of treatment was 2.44% +/- 0.46% (mean +/- standard error) lower than the baseline value. The value at 24 weeks after the end of treatment was 1.10% +/- 0.64% lower than the baseline value. More than 80% of the patients had serum-estradiol levels of 45 pg/ml or less. During treatment, more than 90% of the patients had serum-estradiol levels of 60 pg/ml or less. Genital bleeding was inhibited in 90% of the patients. After 8 weeks of treatment, the clinical symptoms improved in 75% of the patients; such improvement persisted for the duration of the treatment. CONCLUSION: Decreasing the dose of GnRH agonist during treatment can minimize the loss of bone-mineral density without lessening the beneficial effects on endometriosis. This technique might be useful in the management of endometriosis.

Abdominal Pain↗
PubMed1999

Pseudohypoparathyroidism type 1b in pregnancy.

Calcium-regulating hormones were serially measured during the second pregnancy in a woman with pseudohypoparathyroidism type 1b. Calcium levels corrected for serum albumin were maintained almost normal during her second pregnancy with 1alpha-hydroxycalciferol (2.0 microg daily) though they were slightly decreased in late pregnancy. 1,25-Dihydroxyvitamin D levels were higher in early and mid-pregnancy, but not in late pregnancy compared to those after delivery. Parathyroid hormone levels were higher in late pregnancy than after delivery.

Adult↗
PubMed1999

The effect of hyaluronic acid-carboxymethylcellulose in reducing adhesion reformation in rabbits.

The effect of hyaluronic acid-carboxymethylcellulose film (Seprafilm) in reducing postoperative adhesion formation was examined in a rabbit induced-adhesion model. During laparotomy, the ileocaecal region was mechanically and chemically abraded to induce lesions. After a 28-day recovery period, adhesions were lysed by microsurgery and Seprafilm was applied to the lysed lesion in 10 rabbits and six rabbits received physiological saline. A third laparotomy was performed 10-14 days later and the area of adhesion reformation was compared to that found prior to application of test materials. The area of adhesion reformation with Seprafilm decreased to (mean +/- standard deviation) 11.71 +/- 10.97% of the originally lysed lesion and, the area was significantly reduced compared with controls treated with physiological saline. These results suggest that the use of Seprafilm may be a valuable new anti-adhesion material for abdominal or pelvic surgery and may be superior to existing anti-adhesion materials and techniques.

Animals↗
PubMed1999

Large empty sella with an intrasellar herniation of an elongated third ventricle. Case report.

A 73-year-old female presented with a large empty sella with herniation of an elongated third ventricle concomitant with herniation of the surrounding subarachnoid space into the sella, manifesting as visual impairment and amenorrhea without galactorrhea. Magnetic resonance imaging and computed tomography cisternography clearly showed the large empty sella, without evidence of either hydrocephalus or benign intracranial hypertension, which is extremely rare.

Aged↗
PubMed1999

Thrombopoietin expression in normal and hypobaric hypoxia-induced thrombocytopenic rats.

Thrombopoietin (TPO) is important as the physiologic regulator of platelet production. High-altitude hypoxia is a well-known cause of polycythemia and thrombocytopenia in animals. Fifty-two Wistar rats were housed for 0.5 to 21 days in a mechanical chamber in an environment equivalent to that found at 5500 m to determine (a) the cellular localization of TPO and (b) whether the decreased platelet and megakaryocyte counts in rats exposed to a hypobaric hypoxic environment (HHE) are associated with an altered TPO mRNA expression. In normal rats, there were high levels of TPO mRNA in the liver and kidney, intermediate levels in the brain and large intestine, and low levels in the skeletal muscle and small intestine. TPO mRNA and protein were expressed in Purkinje cells and neuronal cells in the brain, in proximal tubular cells and the mesangial cells of the glomeruli in the kidney, in hepatocytes and biliary duct epithelial cells, in absorptive epithelial cells in the large intestine, in the epidermis, and in the lung. The platelet count in the blood and megakaryocyte counts in the bone marrow and spleen were all decreased significantly after 5 or more days of exposure to HHE. In major producers such as the liver and kidney and in minor producers such as the brain, TPO mRNA levels, which tended to be decreased after 0.5 to 3 days of exposure to HHE, had returned to normal by about Day 5 or 7. Thus, during the HHE period with a decreased platelet count, no changes in TPO mRNA levels were detected in these three organs. In conclusion, we have demonstrated that TPO production occurs in various types of cells. In HHE, however, factors other than TPO may be involved in hypobaric hypoxia-induced thrombocytopenia in rats.

Animals↗
PubMed1999

Surviving and proliferating faculty of fibroblasts cultured under no-serum and poor nutritional conditions. The basic study on hybridation of cultured cells with an artificial matrix.

BACKGROUND: In this study, we measured survival periods of fibroblasts cultured under conditions providing minimal nutrition. This investigation aims to develop the high affinity hybrid artificial organs on tissues or organs finally. METHODS: Dermal fibroblasts were inoculated on 96-well multiplate according to routine technique. The medium of these cells maintained for 24 hours replaced the new DME medium containing 10% FBS (group 1) or without FBS (group 2) and then cultured for 10 days without medium change. The surviving cell numbers were measured using MTS assay. RESULTS: Surviving cell numbers of both groups decreased progressively during the 10-day assay period. Overall 25-40% of the fibroblasts survived for at least 10 days. It decreased significantly, however, in group 2 from day 2 through day 4 as compared to group 1. In contrast, the cell number decreased in group 1 to a greater extent than in group 2 after day 6. When the cells that survived until day 10 were then cultured with fresh DME medium containing 10% FBS for 3 more days, the cell numbers returned to 50-100% of the initial level CONCLUSIONS: These results suggest that fibroblasts cell function is maintained under poor nutritional conditions, i.e., without serum, possibly via an autocrine or paracrine mechanism. These data could contribute much to the research of hybrid artificial organs, including an artificial trachea, in which hybridization of cultured cells with artificial matrices remains to be a basic process, and has to serve in bloodless postimplantation period.

Cell Count↗
PubMed1999

Expression of endothelin-1 in rats developing hypobaric hypoxia-induced pulmonary hypertension.

Experimental pulmonary hypertension induced in a hypobaric hypoxic environment (HHE) is characterized by structural remodeling of the heart and pulmonary arteries. Endothelin-1 (ET-1), a 21-amino acid peptide, is a novel and long-lasting vasoconstrictor that increases pulmonary arterial pressure in both in vivo and in vitro experiments. To study the effects of HHE on ET-1 activity in the lungs, 59 male rats were subjected to the equivalent of an altitude of 5500 m for 1 to 4 weeks. In rats exposed to HHE, the mean pulmonary arterial pressure increased significantly from 15.2+/-0.3 (ground level) to 30.6+/-1.5 mm Hg (5500-m level) at 4 weeks, whereas their mean systemic arterial pressure remained normal. The levels of ET-1 mRNA and protein, measured respectively by Northern blot analysis and enzyme immunoassay, increased rapidly in the lungs on exposure to HHE. By in situ hybridization and immunohistochemistry, respectively, ET-1 mRNA and protein were detected in control rats in nonciliated bronchiolar epithelial cells and alveolar epithelial cells, as well as in the endothelial cells of pulmonary arteries, but minimally in the smooth muscle cells of pulmonary arteries. ET-1 mRNA- and protein-reactive smooth muscle cells in pulmonary arteries and ET-1 mRNA-reactive airway epithelial cells were significantly more abundant in rats exposed to HHE than in ground level controls. These results suggest the possibility that in smooth muscle cells in pulmonary arteries and airway epithelial cells, ET-1 may play an autocrine or paracrine role in the remodeling of blood vessels during the development of the pulmonary hypertension that is induced by HHE.

Altitude↗
PubMed1999

[An intervention trial to postpone aging in competent elderly. Trial of nutritional improvement in the retirement home].

The purpose of this study was to evaluate the effectiveness of a comprehensive intervention program in changing dietary habits and nutritional status, for postponing aging in competent elderly. The intervention group (n = 44, 11 men, 33 women, mean age: 74.3 +/- 5.4 years) comprised residents of a retirement home in a suburb of Tokyo. The intervention program, which consisted of 82 lectures and practice sessions focusing mainly on improvement of life styles, was performed between May 1993 and May 1995. In addition, individualized dietary consultations were provided every week during the intervention period. The age and sex matched control group (n = 133, 33 men, 100 women) was randomly selected from participants of the community-based health examination in Tokyo. Changes in dietary habits were measured by a 15-food frequency questionnaire method. As parameters of nutritional status, serum albumin (ALB), total cholesterol (TC), HDL cholesterol (HDL-C) and body mass index (BMI) were simultaneously examined at pre- and post-intervention. The results obtained were as follows: 1) The mean score of Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG Index of Competence) was 11.3 +/- 1.6 in the intervention group, 12.0 +/- 1.6 in the control group, the competent level of functional capacity was equally high in both groups. 2) Food frequencies of meat, fruit, and fat and oil significantly increased in the intervention group. A significant increase in the food frequency of meat was seen in the control group. 3) Significant increases in ALB, HDL-C and BMI were consequently observed in the intervention group, whereas levels of ALB and BMI significantly decreased in the control group. 4) The number of times of participation in the comprehensive intervention program was significantly positively related to the change in ALB between pre- and post-intervention, after adjusted for age, sex, education, TMIG Index of Competence score and ALB level at baseline. These results indicate that the comprehensive intervention program is effective for postponing aging in the competent elderly.

Aged↗
PubMed1998

Caspase-mediated activation of a 36-kDa myelin basic protein kinase during anticancer drug-induced apoptosis.

A novel anticancer drug, cytotrienin A, isolated from Streptomyces sp., induces apoptosis (or programmed cell death) in human promyelocytic leukemia HL-60 cells within 4 h. To elucidate the mechanism of this process, we performed an in-gel kinase assay using myelin basic protein (MBP) as a substrate and found the activation of kinase with an apparent molecular mass of 36 kDa (p36 MBP kinase). The dose of cytotrienin A required to activate p36 MBP kinase was consistent with that required to induce apoptotic DNA fragmentation in HL-60 cells. This p36 MBP kinase was activated with kinetics distinct from the activation of JNK (c-Jun N-terminal kinase)/stress-activated protein kinase and p38 MAPK (mitogen-activated protein kinase). Importantly, the p36 MBP kinase was immunologically different from MAPK superfamily molecules such as ERK1, JNK isoforms, and p38 MAPK. In addition, the p36 MBP kinase activation and apoptotic DNA fragmentation were inhibited by antioxidants such as N-acetylcysteine and reduced-form glutathione. The p36 MBP kinase activation was also observed during hydrogen peroxide (H2O2) and okadaic acid-induced apoptosis. Although a specific inhibitor of caspase-3-like proteases (Ac-DEVD-CHO) or a specific inhibitor of caspase-1-like proteases (Ac-YVAD-CHO) did not block the cytotrienin A-, H2O2-, or okadaic acid-induced apoptosis, a broad specificity inhibitor of caspases (Z-Asp-CH2-DCB) strongly inhibited the apoptosis of HL-60 cells. Surprisingly, Z-Asp-CH2-DCB inhibited the activation of p36 MBP kinase induced by cytotrienin A or H2O2, but did not inhibit the activation of JNK/stress-activated protein kinase and p38 MAPK. Taken together, these results indicate that p36 MBP kinase activation is downstream of the activation of Z-Asp-CH2-DCB-sensitive caspases, and reactive oxygen species could be included in the apoptotic events. Moreover, according to the Western blotting using the antibodies against MST1/Krs2 or MST2/Krs1, it is suggested that the p36 MBP kinase is an active proteolytic product of MST1/Krs2 and MST2/Krs1, which are originally cloned by virtue of its homology to the budding yeast Ste20 kinase. Thus, the p36 MBP kinase might be a common component of the diverse signaling pathways leading to apoptosis, and controlling this p36 MBP kinase pathway might be a novel strategy for cancer chemotherapy.

Antibiotics, Antineoplastic↗
PubMed1998

Induction of apoptosis by Smad3 and down-regulation of Smad3 expression in response to TGF-beta in human normal lung epithelial cells.

Smad family members are essential intracellular signaling components of the transforming growth factor-beta (TGF-beta) superfamily involved in a range of biological activities. Two highly homologous molecules, Smad2 and Smad3, have so far been identified as receptor-activated Smads for TGF-beta signaling and have become the focus of intensive studies. However, no definite differences in regulation or function have been established between these TGF-beta signaling molecules. In the present study, we show that the expression of Smad3, but not its close relative, Smad2, is down-regulated by TGF-beta mediated signals themselves in human lung epithelial cells. This down-regulation of Smad3 by TGF-beta treatment did not appear to result from shortening of the half-life of Smad3 mRNA. Constitutive expression of Smad3 in the presence of TGF-beta induced apoptotic cell death, with an adverse effect on the cell growth of human lung epithelial cells. Apoptotic cell death could also be induced by forced expression of Smad2 in the presence of TGF-beta, but less efficiently than by that of Smad3. These findings clearly define the distinctions between Smad2 and Smad3 for the first time in that a qualitative difference was observed with regard to the regulation of their expression in response to TGF-beta, while Smad2 and Smad3 appeared to have quantitatively different capabilities regarding the induction of apoptotic cell death in human lung epithelial cells.

Apoptosis↗
PubMed1998

Tryprostatin A, a specific and novel inhibitor of microtubule assembly.

We have investigated the cell cycle inhibition mechanism and primary target of tryprostatin A (TPS-A) purified from Aspergillus fumigatus. TPS-A inhibited cell cycle progression of asynchronously cultured 3Y1 cells in the M phase in a dose- and time-dependent manner. In contrast, TPS-B (the demethoxy analogue of TPS-A) showed cell-cycle non-specific inhibition on cell growth even though it inhibited cell growth at lower concentrations than TPS-A. TPS-A treatment induced the reversible disruption of the cytoplasmic microtubules of 3Y1 cells as observed by indirect immunofluorescence microscopy in the range of concentrations that specifically inhibited M-phase progression. TPS-A inhibited the assembly in vitro of microtubules purified from bovine brains (40% inhibition at 250 microM); however, there was little or no effect on the self-assembly of purified tubulin when polymerization was induced by glutamate even at 250 microM TPS-A. TPS-A did not inhibit assembly promoted by taxol or by digestion of the C-terminal domain of tubulin. However, TPS-A blocked the tubulin assembly induced by inducers interacting with the C-terminal domain, microtubule-associated protein 2 (MAP2), tau and poly-(l-lysine). These results indicate that TPS-A is a novel inhibitor of MAP-dependent microtubule assembly and, through the disruption of the microtubule spindle, specifically inhibits cell cycle progression at the M phase.

Animals↗
PubMed1998

Cell cycle arrest and antitumor activity of pironetin and its derivatives.

The biological effects of pironetin and its derivatives on cell cycle progression and antitumor activity were studied. At 10-20 ng/ml, both pironetin and its demethyl derivative, NK10958P completely inhibited the cell proliferation of 3Y1 cells, however, epoxypironetin showed only a weak inhibitory activity. The cell cycle analysis revealed that these compounds arrested the cell cycle progression at the M-phase in a dose-dependent manner. These antiproliferative effects of pironetin were also observed in the range 5-25 ng/ml with several tumor cell lines. In CDF1-SLC mice bearing P388 leukemia cells, the intraperitoneal administration of 6.3 mg/kg pironetin over a 5-day period showed a moderate antitumor effect (T/C, 128%). As the chemical structure of pironetin is different from other M-phase inhibitors such as colchicine or vinblastine, pironetin will be the lead compound for a potential new antitumor drug.

Animals↗
PubMed1998

p27KIP1 in human lung cancers: differential changes in small cell and non-small cell carcinomas.

Small cell lung cancers (SCLCs) and non-small cell lung cancers (NSCLCs), two major categories of human lung cancers, have been shown to exhibit considerably different clinicopathological, biological, and molecular genetic characteristics. Inactivation of cyclin-dependent kinase inhibitors is now thought to play an important part in the pathogenesis of this fatal disease. In the present study, we show that in vitro p27KIP1 expression was associated with cell density-dependent growth inhibition in human lung epithelial cells in vitro, whereas in vivo, p27KIP1 expression in lung cells showed an inverse correlation with proliferative activity in the developing and adult normal lungs. Our immunohistochemical examination of 166 lung tumor specimens also revealed a striking difference in p27KIP1 expression between SCLCs and NSCLCs. Of 149 NSCLCs, 107 (72%) showed reduced p27KIP1 expression, with 8 being virtually negative. Furthermore, p27KIP1 expression status was found to be a significant prognostic factor for patient survival in the analysis of the 149 primary, resected NSCLC cases (P = 0.03 by the log-rank test). In contrast, all SCLC specimens thus far examined exhibited significantly increased staining when compared to the corresponding normal lung epithelium. These findings provide additional evidence for the heterogeneity prevalent in human lung cancers and suggest that p27KIP1 might play distinct biological roles in the pathogenesis of the two major histological categories, warranting additional studies to elucidate the functional consequences of such differences.

Adult↗
PubMed1998

Inhibition of cyclin D1 expression and phosphorylation of retinoblastoma protein by phosmidosine, a nucleotide antibiotic.

In this report, we studied the effect of phosmidosine, a proline-containing nucleotide on the serum-induced cell cycle progression in human lung fibroblast WI-38 cells. Phosmidosine suppressed S-phase entry and arrested cell cycle progression at the G1 phase. In serum-stimulated cells, phosmidosine did not affect the activation of the mitogen-activated protein kinase cascade. However, phosmidosine inhibited hyperphosphorylation of retinoblastoma (RB) protein by RB-kinases such as cyclin-dependent kinase 4 and cyclin-dependent kinase 2, probably as a result of the inhibition of cyclin D1 expression. Furthermore, in tsFT210 cells, a temperature-sensitive cdc2 mutant isolated from the mouse mammary carcinoma cell line FM3A, phosmidosine, irreversibly inhibited the cell cycle progression at G1 without affecting the G2 to M transition. Phosmidosine acts at an earlier point in G1 compared with mimosine or aphidicolin, well-known cell cycle blockers at the G1-S boundary. Taken together, phosmidosine arrested cells at a specific point between the start point and restriction point in G1 and is a useful drug that may contribute to the understanding of the regulatory mechanisms of G1 progression.

Animals↗