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Biomedical subjects

Reiko Tanaka

Publications and source records attributed to Reiko Tanaka.

54 records · Page 3Linked to original sources
PubMed2003

A duodenally absorbable CXC chemokine receptor 4 antagonist, KRH-1636, exhibits a potent and selective anti-HIV-1 activity.

A low molecular weight nonpeptide compound, KRH-1636, efficiently blocked replication of various T cell line-tropic (X4) HIV type 1 (HIV-1) in MT-4 cells and peripheral blood mononuclear cells through the inhibition of viral entry and membrane fusion via the CXC chemokine receptor (CXCR)4 coreceptor but not via CC chemokine receptor 5. It also inhibited binding of the CXC chemokine, stromal cell-derived factor 1alpha, to CXCR4 specifically and subsequent signal transduction. KRH-1636 prevented monoclonal antibodies from binding to CXCR4 without down-modulation of the coreceptor. The inhibitory effect against X4 viral replication by KRH-1636 was clearly reproduced in the human peripheral blood lymphocytesevere combined immunodeficiency mouse system. Furthermore, this compound was absorbed into the blood after intraduodenal administration as judged by anti-HIV-1 activity and liquid chromatography MS in the plasma. Thus, KRH-1636 seems to be a promising agent for the treatment of HIV-1 infection.

Animals↗
PubMed2003

Potential antitumor promoting diterpenoids from the stem bark of Thuja standishii.

Six diterpenes, including one new natural product, were isolated from a CHCl 3 extract of the stem bark of Thuja standishii. The new compound has been characterized as 15-oxolabda-8(17),13 Z-dien-19-oic acid. The known compounds were identified as ferruginol (2), sugiol (3), isocupressic acid (4), sandaracopimaric acid (5) and 15-oxolabda-8(17),13 E-dien-19-oic acid (6). Compounds 2-5 and the derivatives 4a and 4b were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). Compounds 2, 3, 4 and 5 showed strong inhibitory effect on EBV-EA induction (100 % inhibition at 1000 mol ratio/TPA).

Antineoplastic Agents, Phytogenic↗
PubMed2003

Two new anti-tumor promoting serratane-type triterpenoids from the stem bark of Picea jezoensis var. jezoensis.

Two new serratane-type triterpenoids, 1 and 2, were isolated from the stem bark of Picea jezoensis Carr. var. jezoensis (Pinaceae). Their structures were determined to be 3beta-methoxyserrat-13-en-21beta-ol (1) and 13beta, l4beta-epoxy-3beta-methoxyserratan-21beta-ol (2) on the basis of spectroscopic methods and partial syntheses. Compounds 1 and 2 and their acetates were screened as potential anti-tumor promoters by using the in vitro short-term 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced Epstein-Barr virus early antigen (EBV-EA) activation assay. IC50 value evaluation showed that compound 1 was more effective than others. In addition, compounds 1 and 2 were examined for anti-tumor promoting activities in a two-stage carcinogenesis assay of mouse skin tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. Compounds 1 and 2 exhibited significant anti-tumor promoting effects on mouse skin carcinogenesis.

Animals↗
PubMed2003

Induction of protective immune responses against R5 human immunodeficiency virus type 1 (HIV-1) infection in hu-PBL-SCID mice by intrasplenic immunization with HIV-1-pulsed dendritic cells: possible involvement of a novel factor of human CD4(+) T-cell origin.

The potential of a dendritic cell (DC)-based vaccine against human immunodeficiency virus type 1 (HIV-1) infection in humans was explored with SCID mice reconstituted with human peripheral blood mononuclear cells (PBMC). HIV-1-negative normal human PBMC were transplanted directly into the spleens of SCID mice (hu-PBL-SCID-spl mice) together with autologous mature DCs pulsed with either inactivated HIV-1 (strain R5 or X4) or ovalbumin (OVA), followed by a booster injection 5 days later with autologous DCs pulsed with the same respective antigens. Five days later, these mice were challenged intraperitoneally with R5 HIV-1(JR-CSF). Analysis of infection at 7 days postinfection showed that the DC-HIV-1-immunized hu-PBL-SCID-spl mice, irrespective of the HIV-1 isolate used for immunization, were protected against HIV-1 infection. In contrast, none of the DC-OVA-immunized mice were protected. Sera from the DC-HIV-1- but not the DC-OVA-immunized mice inhibited the in vitro infection of activated PBMC and macrophages with R5, but not X4, HIV-1. Upon restimulation with HIV-1 in vitro, the human CD4(+) T cells derived from the DC-HIV-1-immunized mice produced a similar R5 HIV-1 suppressor factor. Neutralizing antibodies against human RANTES, MIP-1alpha, MIP-1beta, alpha interferon (IFN-alpha), IFN-beta, IFN-gamma, interleukin-4 (IL-4), IL-10, IL-13, IL-16, MCP-1, MCP-3, tumor necrosis factor alpha (TNF-alpha), or TNF-beta failed to reverse the HIV-1-suppressive activity. These results show that inactivated HIV-1-pulsed autologous DCs can stimulate splenic resident human CD4(+) T cells in hu-PBL-SCID-spl mice to produce a yet-to-be-defined, novel soluble factor(s) with protective properties against R5 HIV-1 infection.

AIDS Vaccines↗
PubMed2003

Noninvasive method for monitoring Pneumocystis carinii pneumonia.

The progression of Pneumocystis carinii pneumonia was temporally monitored and quantified by real-time polymerase chain reaction of P. carinii-specific DNA in oral swabs and lung homogenates from infected rats. DNA levels correlated with the number of P. carinii organisms in the rats' lungs, as enumerated by microscopic methods. This report is the first of a noninvasive, antemortem method that can be used to monitor infection in a host over time.

Animals↗
PubMed2003

Analysis of serotype AD strains from F1 progenies between urease-positive- and negative-strains of Cryptococcus neoformans.

Cryptococcus neoformans is a pathogenic basidiomycete with a defined sexual cycle involving mating between haploid yeast cells with a transient diploid state. We examined F1 progeny from a crossing between the urease-negative strain (environmental isolate, serotype A, mating type alfa, haploid) and a tester strain (B 3502 from NIH of USA; urease-positive, serotype D, mating type a, haploid) for serotype, mating type, ploidy and urease activity, and performed partial sequencing of the urease gene. Phenotypes of the F1 progeny and results of SSCP analyses suggested that the serotype AD strain of the F1 progeny is a hybrid of the parental serotype A and D strains.

Cryptococcus neoformans↗
PubMed2002

Serologic responses to epitopes of the major surface glycoprotein of Pneumocystis jiroveci differ in human immunodeficiency virus-infected and uninfected persons.

The major surface glycoprotein (Msg) of Pneumocystis jiroveci (P. jiroveci) is important in the immunopathogenesis of Pneumocystis pneumonia (PcP), but is difficult to study in humans. We generated 3 overlapping recombinant Msg fragments (MsgA, MsgB and MsgC), and analyzed their reactivity with serum samples from 95 healthy blood donors and 94 human immunodeficiency virus (HIV)-infected persons. Reactivity to the Msg fragments varied with HIV infection and prior episodes of PcP but not with geographic origin. Recognition of MsgA was lower-and recognition of MsgB was significantly lower-in HIV(+) serum compared with donor serum. Serum samples from HIV-positive patients with prior PcP recognized MsgC more frequently than did serum samples from those without PcP. None of the serum samples drawn from 9 patients before they had developed PcP recognized MsgC. These data suggest that these novel recombinant proteins are useful for the analysis of antibody responses to Msg.

Amino Acid Sequence↗
PubMed2002

Lack of modification of rat hepatocarcinogenesis by fernane-type triterpenoids, isolated from a Euphorbia genus.

Inhibitors of topoisomerases, enzymes that produce an unusual type of DNA damage, are considered as antitumor agents. Recently it has been reported that the fernane-type triterpenoid EC-2 and its hydroxyl derivative, isolated from Euphorbia, are potent topoisomerase II inhibitors. In this study, the modifying effects of EC-2 and EC-4 on the development of putative preneoplastic lesions, glutathione S-transferase placental form (GST-P)-positive foci, in the liver of rats were investigated using a medium-term bioassay system. Fisher 344 male, 6-week-old rats were given a single intraperitoneal injection (200 mg/kg b.w.) of diethylnitrosamine or saline at the beginning of the experiment and subjected to 2/3 partial hepatectomy at the 3rd week. The test compounds were administered five times/week by i.g. gavage at a dose of 1 mg/kg b.w. from 2 to 8 weeks. Quantitation of the numbers and areas per cm(2) of induced GST-P positive foci did not demonstrated any significant differences among the groups and no variation in cell proliferation as indicated by 5-bromo- 2'-deoxyuridine (BrdU) labeling. Our results suggest that EC-2 and EC-4 have no modifying effects on rat hepatocarcinogenesis.

Animals↗
PubMed2002

Potential antitumor-promoting diterpenes from the cones of Pinus luchuensis.

A new nor-labdane-type diterpene, 15-nor-labda-8(17),12E-dien-13,19-dienoic acid (1), along with five known diterpenes, 15-nor-14-oxolabda-8(17),12E-dien-19-oic acid (2), trans-communic acid (3), sandaracopimaric acid (4), dehydroabietic acid (5), and abieta-8,11,13-triene-15,18-diol (6), was isolated from the cones of Pinus luchuensis. The structure of 1 was established by chemical and spectroscopic methods. Among these isolates, compounds 2, 4, and 6 showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate.

Antigens, Viral↗
PubMed2002

Triterpenoid constituents isolated from the bark of Abies sachalinensis.

Three new lanostane-type triterpenoids (1-3) were isolated from the bark of Abies sachalinensis along with a known compound (4). The structures of 1-4 were characterized by spectroscopic methods including NMR and MS. Compound 4 and some derivatives were tested for inhibitory effects on in vitro DNA topoisomerases I and II and found to be selective catalytic inhibitors of topoisomerase II activity with IC(50) values in the range 43-76 microM.

Abies↗
PubMed2002

Aromatase inhibitory activities of standishinal and the diterpenoids from the bark of Thuja standishii.

The absolute stereostructure of a novel skeletal diterpene, standishinal (1), from the bark of Thuja standishii was confirmed by X-ray crystallographic analyses of 1 and its p-bromobenzoate derivative. Aromatase inhibitory activities of standishinal, eight known diterpenes, totarol, 12-methoxyabieta-8,11,13-trien-11-ol, 12-hydroxy-6,7-seco-abieta-8,11,13-triene-6,7-dial, trans-communic acid, labda-8(17),13-dien-12 R,15-olid-19-oic acid, 12 S-hydroxylabda-8(17),13(16),14-trien-19-oic acid, 13-oxo-15,16-dinorlabda-8(17),11 E-dien-19-oic acid and 14-oxo-15-norlabda-8 (17),12 E-dien-19-oic acid from the plant, and four synthetic analogs were evaluated using a recombinant human aromatase. Among them, standishinal and its diacetate derivative had significant inhibitory activities.

Abietanes↗
PubMed2002

A relative high dose of vitamin E does not attenuate unweighting-induced oxidative stress and ubiquitination in rat skeletal muscle.

We previously reported that intragastric administration of cysteine could be beneficial to prevent unweighting-induced ubiquitination and degradation of muscle protein in association with redox regulation [Ikemoto et al., Biol. Chem., 383 (2002), 715-721]. In this study, we investigated whether vitamin E, another potent antioxidative nutrient, also had beneficial effects on the muscle protein catabolism. However, daily intragastric supplementation of 1.5 or 15 mg/rat of alpha-tocopherol did not prevent weight loss of hindlimb skeletal muscle in tail-suspended rats. To elucidate the reason for the non-effectiveness of vitamin E, we further examined concentrations of oxidative stress markers, ubiquitination of muscle proteins and fragmentation of myosin heavy chain in gastrocnemius muscle of rats daily treated with 15 mg of alpha-tocopherol. Unexpectedly, vitamin E increased concentrations of glutathione disulfide and thiobarbituric acid-reactive substance and decreased glutathione level in the muscle, compared with those of vehicle treatment, indicating that vitamin E enhanced unweighting-induced oxidative stress in skeletal muscle. The vitamin E supplementation did not suppress the ubiquitination of muscle proteins and fragmentation of myosin heavy chain caused by tail-suspension. Our results suggest that supplementation of a relative high dose of vitamin E could not inhibit ubiquitin-dependent degradation of muscle protein in tail-suspended rats possibly due to its prooxidant action.

Animals↗
PubMed2002

The first isolation of Hortaea werneckii from a household guinea pig.

Hortaea werneckii, a black yeast and the causative agent of tinea nigra (a superficial type of dermatomycosis), is a human pathogen and is also found in the environment. It is not highly pathogenic but in the last fifteen to twenty years has been isolated from various human and environmental sources in Japan. As far as we know, there has been no report on the isolation of H. werneckii from animals. Recently, we found a case of a guinea pig with dark superficial lesions on the palm and dorsal areas. Cultural and morphological studies of scrapings from the lesion showed that the causative agent was a black yeast, which was identified as H. werneckii by morphological study and molecular biological screening. D1/D2 region of the 26S large subunit rDNA gene of this isolate was identical to those of 11 other H. werneckii isolates used as reference strains in this study. This is the first case recorded of tinea nigra caused by H. werneckii in a guinea pig.

Animals↗
PubMed2002

Histopathological examination of in vitro bone degeneration caused by a black yeast, Exophiala spinifera.

Exophiala spinifera, a black yeast, rarely causes systemic infection, and only a very few cases of its infection by the invasion of internal organs or bones have been reported. We examined the ability of E. spinifera to invade bone tissues in vitro. The fungus was inoculated on the surface of murine bones, and then these bones were incubated at 30 C for 2, 4, and 12 weeks on water agar plates and on brain heart infusion agar supplemented with 1%glucose (BHIA) plates. Histopathological examination demonstrated that the fungus was initially found in the non-calcified parts of the bone tissue, such as the growth plate and articular cartilage. Thereafter, the fungus invaded the calcified parts: cancellous and cortical bones. Our experiments showed that the capability of E. spinifera to invade bone tissue is higher than that of Candida albicans or other black fungi. E. spinifera grew in the mycelial form and C. albicans in the yeast form in these experiments. Our results suggest that E. spinifera may have a high potential to invade bone tissues, and that the mycelial form can invade bone more deeply than the yeast form. Therefore, bone degeneration should/ must be carefully monitored in any systemic infection with E. spinifera.

Animals↗
PubMed1998

Tetracyclic triterpenes and other constituents from the leaves and bark of Larix kaempferi.

Two new triterpenes were isolated from the leaves of Larix kaempferi together with two known compounds, 24-methylenecycloartanone and 24-methylenecycloartanol. A new triterpene-triol, nine known compounds, n-alkyl trans-ferulates and trans-p-coumarates, rheosmin, five stigmastanes and friedelin were isolated from the stem bark. These new compounds were characterized as cycloartan-3,24-dione, 24-methylenecycloartan-3alpha-ol and lanost-9(11)-en-3alpha,24S,25-triol on the basis of chemical and spectroscopic evidence.

Journal Article↗
PubMedDate not supplied

Cysteine supplementation prevents unweighting-induced ubiquitination in association with redox regulation in rat skeletal muscle.

We have previously reported that spaceflight and tail suspension enhanced degradation of rat myosin heavy chain (MHC) in association with activation of a ubiquitin-dependent proteolytic pathway [Ikemoto et al., FASEB J. 15 (2001), 1279-1281]. To elucidate whether the ubiquitination is accompanied by oxidative stress, we measured markers for oxidative stress, such as thiobarbituric acid-reactive substance (TBARS) and glutathione disulfide (GSSG), in gastrocnemius muscle of tail-suspended rats. Glutathione (GSH) concentration in the muscle significantly decreased from day 5 and reached a minimum value on day 10. Tail suspension reciprocally increased concentrations of TBARS and GSSG in parallel with enhancement of protein ubiquitination, suggesting that oxidative stress may play an important role in protein ubiquitination caused by tail suspension. To prevent ubiquitination associated with oxidative stress, we also administered an antioxidative nutrient, cysteine, to tail-suspended rats. Intragastric supplementation of 140 mg/rat of cysteine for 2 weeks or longer normalized the ratio of GSH to GSSG in the muscle and suppressed protein ubiquitination and MHC fragmentation, compared with supplementation of the equimolar amount of alanine. The cysteine supplementation significantly suppressed the loss of hindlimb muscle mass. Our results suggest that supplementation of antioxidative nutrients, such as cysteine, may be beneficial for preventing ubiquitination of muscle proteins caused by unweighting.

Animals↗