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Biomedical subjects

T Okamoto

Publications and source records attributed to T Okamoto.

At least 217 records · Page 12Linked to original sources
PubMed2000

Function and X chromosome inactivation analysis of B lymphocytes in myelodysplastic syndromes with immunological abnormalities.

To investigate the pathogenesis of immunological abnormalities (IA) in myelodysplastic syndrome (MDS), we examined B cells for their ability to produce cytokine and their X chromosome inactivation pattern (XCIP). An IA was defined as being positive for at least one autoimmune laboratory test (e.g. antinuclear antibody, rheumatoid factor). Seventy-three MDS patients [65 with refractory anemia (RA), 3 with RA with excess blasts (RAEB), and 5 with RAEB in transformation] were examined; 47 had IA and 26 had no IA. To examine the function of B cells in MDS, the production of interleukin (IL)-6 and IL-10 was measured in cultures of purified B cells with or without stimulators. Both IL-6 and IL-10 production rates in patients with IA were significantly higher than in patients without IA and normal controls. The skewing of XCIP of B cells was analyzed by using the polymerase chain reaction, and the skewing rate of B cell XCIP was quantitatively assayed by compared to control T lymphocytes. The skewing rate of B cells was higher in patients with IA than in those without IA and normal controls. Therefore, a small population of B cells in patients with IA might be derived from MDS clones, and be associated with the induction of IA.

Adolescent↗
PubMed2000

New imaging findings in a patient with central nervous system dysfunction after bone marrow transplantation.

Central nervous system disorders are an important complication of bone marrow transplantation (BMT). We have recently performed cerebral angiography to examine central nervous system dysfunction in a 22-year-old woman with acute lymphoblastic leukaemia who had undergone BMT. Angiography demonstrated multiple stenoses and occlusions in the peripheral branches of the anterior and middle cerebral arteries, a pattern similar to that seen in vasculitis. She was thought to most likely have cytomegalovirus (CMV) vasculitis, but other forms of vasculitis, such as angiitis-like-syndrome-associated graft-versus-host disease could not be excluded. This case suggests that CMV vasculitis may cause central nervous system dysfunction after BMT and that imaging studies may provide useful information about central nervous system disorders in these patients.

Adult↗
PubMed2000

Acute promyelocytic leukemia with marrow fibrosis at initial presentation: possible involvement of transforming growth factor-beta(1).

Although the occurrence of marrow fibrosis in acute myeloid leukemia has been described, there have been no reports of acute promyelocytic leukemia (APL) associated with marrow fibrosis. Here we describe an APL patient with severe marrow fibrosis at initial presentation. He had the typical manifestations of APL, except for marrow fibrosis. Complete remission was achieved by treatment with all-trans retinoic acid plus chemotherapy, and his marrow fibrosis gradually improved concomitantly with the decrease in leukemic cells. To clarify the mechanism of marrow fibrosis in this patient, we investigated the expression of genes for several cytokines promoting fibrosis by the reverse transcriptase polymerase chain reaction methods. An overexpression of transforming growth factor-beta(1) was noted in his leukemic cells at initial presentation, whereas no increase in expression was observed at the time of relapse when he no longer had marrow fibrosis. These findings suggest that overexpression of transforming growth factor-beta(1) was involved in the development of marrow fibrosis in this APL patient.

Adult↗
PubMed2000

Deletion polymorphisms in the angiotensin converting enzyme gene are associated with pulmonary hypertension evoked by exercise challenge in patients with chronic obstructive pulmonary disease.

Angiotensin converting enzyme (ACE) plays an important role in the pathogenesis of pulmonary hypertension. In this study we determined whether the deletion (D)/insertion (I) polymorphism in the ACE gene may be associated with pulmonary hypertension evoked by exercise challenge in patients with chronic obstructive pulmonary disease (COPD). ACE genotypes were determined in 19 patients with COPD. All patients underwent right heart catheterization followed by a constant-load exercise test while breathing room air or oxygen. Subgroups were created of seven patients with the II genotype, six with the ID genotype, and six with the DD genotype who were well-matched with respect to age, blood gas data at rest or after exercise, baseline lung function, results of incremental exercise testing, and hemodynamic data at rest. The mean pulmonary arterial pressure (Ppa) and pulmonary vascular resistance (Rpv) at rest in the three subgrpoups did not differ significantly during breathing of either room air or oxygen. However, the Ppa after exercise challenge in patients with the DD genotype (55.7 +/- 4.9 mm Hg [mean +/- SD]) was significantly higher than in patients with the II genotype (42.6 +/- 7.1 mm Hg, p = 0.008). The Rpv after exercise in patients with the DD genotype was also significantly higher than in patients with the ID and II genotypes. During breathing of oxygen to diminish acute hypoxic pulmonary vasoconstriction, the Ppa in patients with the DD genotype (52.3 +/- 3.1 mm Hg) was higher than in patients with the ID genotype (40.5 +/- 5.9 mm Hg, p = 0.0049) or the II genotype (37.7 +/- 5.9 mm Hg, p = 0.0027). In addition, the Rpv in patients with the DD genotype was higher than in patients with the ID and II genotypes. These results suggest that D-I polymorphism in the ACE gene may be associated with pulmonary hypertension evoked by exercise challenge in patients with COPD. However, the number of patients in this study was very small for a genetic association study, and our results should be examined in larger studies.

Aged↗
PubMed2000

Characteristic elevation of matrix metalloproteinase activity in idiopathic interstitial pneumonias.

Destruction of subepithelial basement membrane is a key event in the pathogenesis of idiopathic pulmonary fibrosis (IPF). To evaluate the role of matrix metalloproteinases (MMPs) in parenchymal remodeling in idiopathic interstitial pneumonia (IIP), we studied MMP-2 and -9 activity, in bronchoalveolar lavage fluid (BALF) by zymography and the expression of MMP-2 and -9 and TIMP-2 in lung tissue by immunohistochemistry. BALF and lung tissues were collected from 26 patients with usual interstitial pneumonia (IPF-UIP), 11 with nonspecific interstitial pneumonia (NSIP), and 6 with bronchiolitis obliterans organizing pneumonia (BOOP). IPF-UIP cases showed predominant expression of MMP-9, whereas NSIP and BOOP cases showed predominant MMP-2 expression in BALF and in tissues. In BALF samples from rapidly progressive IPF-UIP cases, neutrophil-derived MMP-9 activity, as well as MMP-9 active form were characteristically detected. Furthermore, the MMP-9 activity correlated significantly with an increase of neutrophils in BALF, whereas the MMP-2 activity associated with NSIP and BOOP correlated with an increase of lymphocytes. These results indicate that MMP-9 in IPF-UIP and MMP-2 in NSIP and BOOP may contribute to pulmonary structural remodeling through type IV collagenolytic activity. The characteristic contributions of matrix-degrading proteins may relate to the distinct prognostic features of these diseases.

Adult↗
PubMed2000

A potential role of activated NF-kappa B in the pathogenesis of euthyroid sick syndrome.

Euthyroid sick syndrome, characterized by low serum 3,5, 3'-triiodothyronine (T(3)) with normal L-thyroxine levels, is associated with a wide variety of disorders including sepsis, malignancy, and AIDS. The degree of low T(3) in circulation has been shown to correlate with the severity of the underlying disorders and with the prognosis. Elevated TNF-alpha levels, which accompany severe illness, are associated with decreased activity of type I 5'-deiodinase (5'-DI) in liver, leading us to speculate that high levels of this factor contribute to euthyroid sick syndrome. Here we demonstrate that the activation of NF-kappa B by TNF-alpha interferes with thyroid-hormone action as demonstrated by impairment of T(3)-dependent induction of 5'-DI gene expression in HepG2 cells. Inhibition of NF-kappa B action by a dominant-negative NF-kappa B reversed this effect and allowed T(3) induction of 5'-DI. Furthermore, we show that an inhibitor of NF-kappa B activation, clarithromycin (CAM), can inhibit TNF-alpha-induced activation of NF-kappa B and restore T(3)-dependent induction of 5'-DI mRNA and enzyme activity. These results suggest that NF-kappa B activation by TNF-alpha is involved in the pathogenesis of euthyroid sick syndrome and that CAM could help prevent a decrease in serum T(3) levels and thus ameliorate euthyroid sick syndrome.

Anti-Bacterial Agents↗
PubMed2000

Expression of cyclooxygenase mRNA in the livers of mice with interferon-gamma chronic hepatitis.

Interferon-gamma (IFN-gamma) transgenic mice expressed the IFN-gamma gene in the liver and developed chronic hepatitis. The expression of cyclooxygenase (Cox)-1 and -2 mRNA were studied in the livers of these mice. A faint band of Cox-1 mRNA was observed in the livers of both normal and transgenic mice. Slight expression of Cox-2 mRNA was observed in the normal mouse liver, and this mRNA expression was induced in the transgenic mouse liver. The present results showed the induction of Cox-2 mRNA expression in the livers of transgenic mice with chronic hepatitis.

Animals↗
PubMed2000

Concanavalin A-induced discharge of glycocalyx of raphidophycean flagellates, Chattonella marina and Heterosigma akashiwo.

Chattonella marina and Heterosigma akashiwo, known as red tide phytoplankton, are naturally wall-less and have quite fragile cell structures. In this study, we found that an equilibrium dialysis technique allowed the study of lectin binding to these flagellates. The results suggested that concanavalin A (Con A) binds to these flagellate cells through the specific carbohydrate moieties on the cell surface. Interestingly, the binding of an excess of Con A on the cell surface caused morphological changes concomitant with discharge of glycocalyx, a polysaccharide-containing common structure on the external cell surface of these flagellates. Fluorescent microscopic observation using FITC-labeled Con A (F-Con A) confirmed that F-Con A molecules are localized on the discharged glycocalyx.

Animals↗
PubMed2000

Family 19 chitinases from Streptomyces thermoviolaceus OPC-520: molecular cloning and characterization.

Family 19 chitinase genes, chi35 and chi25 of Streptomyces thermoviolaceus OPC-520, were cloned and sequenced. The chi35 and chi25 genes were arranged in tandem and encoded deduced proteins of 39,762 and 28,734 Da, respectively. Alignment of the deduced amino acid sequences demonstrated that Chi35 has an N-terminal domain and a catalytic domain and that Chi25 is an enzyme consisting of only a catalytic domain. Amino acid sequences of the catalytic domains of both enzymes, which are highly similar to each other, suggested that these enzymes belong to the family 19 chitinases. The cloned Chi35 and Chi25 were purified from E. coli and S. lividans as a host, respectively. The optimum pH of Chi35 and Chi25 were 5-6, and the optimum temperature of Chi35 and Chi25 were 60 and 70 degrees C, respectively. Chi35 bound to chitin, Avicel, and xylan. On the other hand, Chi25 bound to these polysaccharides more weakly than did Chi35. These results indicate that the N-terminal domain of Chi35 functions as a polysaccharide-binding domain. Furthermore, Chi35 showed more efficient hydrolysis of insoluble chitin and stronger antifungal activity than Chi25. In the polysaccharide-binding domain of Chi35, there are three reiterated amino acid sequences starting from C-L-D and ending with W, and the repeats were similar to xylanase (STX-I) from the same strain. However, the repeats did not show sequence similarity to any of the known chitin-binding domains and cellulose-binding domains.

Amino Acid Sequence↗
PubMed2000

Identification and characterization of a potent antibacterial agent, NH125 against drug-resistant bacteria.

New imidazole compounds were synthesized to develop a novel and effective antibacterial agent (1-benzyl-3-cetyl-2-methylimidazolium iodide, NH125). In vitro experiments demonstrated that NH125 effectively inhibited a number of different histidine protein kinases. Furthermore, oxacillin-resistant Staphylococcus aureus (ORSA), vancomycin-resistant Enterococcus faecalis (VRE), penicillin-resistant Streptococcus pneumoniae (PRS), and other Gram-positive and Gram-negative bacteria were found to be very sensitive to NH125.

Anti-Bacterial Agents↗
PubMed2000

Isolation and serum-free culture of epithelial cells derived from epithelial rests of Malassez in human periodontal ligament.

To study biological character and function of epithelial rests of Malassez (ERM) in human periodontal ligament, we have developed a serum-free culture system of epithelial cells (ME) derived from ERM. The mitogenic effects of fibroblast growth factor (FGF)-1, FGF-2, and FGF-7/keratinocyte growth factor (KGF) on ME, human periodontal ligament-derived fibroblasts (PLF), human oral epithelial cells (OE), and human submandibular gland-derived epithelial cells (SGE) were investigated under a serum-free culture condition. FGF-1 and FGF-7/KGF stimulated the growth of both ME and SGE but FGF-2 had no effect. On the other hand, FGF-1, FGF-2, and FGF-7/KGF increased the OE proliferation. These results suggested that the divergent requirement of FGF ligands among these cells would be attributed to the different expression pattern of FGF receptor (FGFR) messenger ribonucleic acid (mRNA) isotypes. Therefore, we examined the expression of FGFR isotypes in these cells. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of ME-and SGE-derived mRNAs revealed the presence of mRNA encoding FGFR2-IIIb, a high affinity receptor for FGF-1 and FGF-7/KGF. However, no mRNAs for other FGFR isotypes were detected in both ME and SGE. On the contrary, OE expressed FGFR1-IIIc, FGFR3-IIIb, and FGFR4 mRNAs as well as FGFR2-IIb. These results indicate that FGF binding sites on ME dominantly bind to FGF-1 and FGF-7/KGF, which transduce their signals via FGFR2-IIIb. Immunohistochemical analysis, PCR-Southern, ribonuclease protection assay (RPA), and Western blotting revealed that PLF expressed FGF-7/KGF mRNA and its peptide. These observations suggest that FGF-7/KGF might mediate epithelial-mesenchymal interactions between ME and PLF to maintain normal structure and function of periodontal ligament.

Blotting, Southern↗
PubMed2000

Optical waveguide absorption sensor using a single coupling prism.

We propose an optical waveguide sensor that uses a leaky guided mode for measuring absorption of liquid samples. The sensor is composed of a single coupling prism on which a cladding layer and a waveguide layer are deposited. The guided mode generates dips in the reflectance spectrum; the depths of the dips depend on the extinction coefficient of a sample facing the layer. The sensitivity of the sensor is controlled by the thickness of the cladding layer. A simple theoretical model has been developed to analyze the behaviors of the sensor. In experiments we obtained sensitivity 17 times higher than that obtained by the conventional attenuated total reflection method.

Journal Article↗
PubMed2000

Ultraviolet absorbance at 260 and 280 nm in RNA measurement is dependent on measurement solution.

RNA measurement is conducted by measuring ultraviolet absorbance at 260 nm and 280 nm. Calculation of the RNA concentration is based on the absorbance at 260 nm. Furthermore, RNA purity is judged as the 260 nm/280 nm ratio and a low ratio indicates contamination by protein. Diethyl-pyrocarbonate (DEPC)-treated water is used to dissolve RNA and 2-amino-2-hydroxymethyl-1,3-propandiol (Tris) is frequently added to the RNA dissolving solution in order to stabilize the RNA. In the present study, RNA was isolated from mouse liver, and then the influence of DEPC-treated water and Tris-buffer on RNA measurement was studied. The 260 nm/280 ratio of RNA determined after diluting it with distilled water was 1.82+/-0.01 (n=5). DEPC-treated water did not affect the absorbance at 260 nm, but elevated that at 280 nm. Thus, the 260 nm/280 nm ratio was as low as 1.52+/-0.01 (n=5). Tris-HCl (1 M, pH 7.0 or 10.0) lowered the absorbance at 260 nm and even more at 280 nm. Thus, the 260 nm/280 nm ratio was elevated to more than 2.17 (n=5). The present results clearly showed the influence of the measurement solution on RNA measurement.

Animals↗
PubMed2000

Carbon tetrachloride treatment induces anorexia independently of hepatitis in rats.

Oxidative stress is involved in the development of anorexia. In the present study, we examined the possible involvement of anorexia in oxygen radical-induced hepatitis. A low dose of carbon tetrachloride (1 ml/kg of a 1:1 solution with olive oil) was orally administered to rats with and without food restriction. In rats with food restriction, carbon tetrachloride treatment induced hepatitis and reduced the body weight gain. In contrast, carbon tetrachloride treatment did not induce hepatitis in rats without food restriction, but the body weight was decreased. In these rats, the loss of body weight was accompanied by a decrease in food intake. The present results indicate that the administration of a low dose of carbon tetrachloride to rats without food restriction induced anorexia independently of hepatitis.

Animals↗
PubMed2000

Expression of the inducible form of the nitric oxide synthase gene in the livers of mice with chronic hepatitis.

The interferon-gamma (IFN-gamma) transgenic mouse expresses the exogenous IFN-gamma gene in the liver and develops chronic hepatitis. For the present experiment, four IFN-gamma transgene (+) mice of 48 weeks of age and 16 IFN-gamma transgene (+) mice of 8 weeks of age were used. The four IFN-gamma transgene (+) mice of 48 weeks of age showed significantly elevated plasma alanine aminotransferase (ALT) and expressed the inducible form of nitric oxide synthase (iNOS) mRNA in the liver. Of the 16 IFN-gamma transgene (+) mice of 8 weeks of age, iNOS mRNA was expressed in the livers of three. These three mice exhibited higher plasma ALT levels than the other mice of 8 weeks of age. The present results suggest that iNOS mRNA expression in the liver might be correlated with the progression of hepatitis.

Alanine Transaminase↗
PubMed2000

Expression of cyclooxygenase-1 and -2 mRNA in rat tissues: tissue-specific difference in the expression of the basal level of mRNA.

The expression of cyclooxygenase (Cox)-1 and -2 mRNA was studied in tissues of Fisher 344 (F344) (n=3) and Brown Norway (BN) (n=3) strain rats using the reverse transcription polymerase chain reaction. Cox-1 mRNA was expressed in the liver, kidney and lung, but not in the heart. Cox-2 mRNA was expressed in the kidney, heart and lung, but not in the liver. The present results showed the differential expression of basal Cox-1 and Cox-2 mRNA in the rat tissues, suggesting that Cox-1 and Cox-2 may contribute to the regulation of normal pathophysiological conditions in a tissue-specific manner. Thus, it is desirable to perform mapping of the basal expression of Cox-1 and Cox-2 in specific organs in the body in order to anticipate the effects of non-steroidal anti-inflammatory drugs on normal pathophysiological conditions. Finally, no difference was observed between F344 and BN rat tissues in the levels of Cox-1 and Cox-2 mRNA expression.

Animals↗