[Granuloma inguinale (donovanosis)].
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Biomedical subjects
Publications and source records attributed to H Kojima.
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Apolipoprotein (apo)A-I alone or as a component of high density lipoprotein particles has antiatherogenic properties. The age-dependent decline in abundance of this protein may underlie the higher risk for developing occlusive coronary artery disease (CAD) in older individuals. Similar to humans, expression of rat apoA-I also declines with age. Results in rats showed that levels of serum apoA-I protein, hepatic mRNA, and transcription of the gene were decreased to 39%, 18%, and 38%, respectively, in 180-day-old animals compared to those of newborn rats. These findings suggest that a nuclear mechanism(s) may account for the decline in apoA-I expression. Accordingly, we examined hepatic nuclear binding activity to four specific cis-acting elements of the rat apoA-I promoter. There were age-dependent changes of binding activity to two proximal sites, B and C, but not to the more distal elements, IRCE and A. Decreased B-site binding activity correlated with lower mRNA levels encoding the activator, HNF-3beta. The age-dependent change in the pattern of binding to site C was due to a switch from the activator, HNF-4, to the repressor, ARP-1. In summary, the age-related decline in apoA-I expression may arise from a reduction in the activity of both cis-acting elements, B and C.
Circadian variations in chemotherapy toxicity and antitumor effects were investigated in experimental and clinical studies. In the experimental study, Balb/c mice bearing murine colon carcinoma Colon 26 were treated with 4 injections of 5-fluorouracil (5-FU) (80 mg/kg) at 0000 Hours After Light On (HALO), 0600 HALO, 1200 HALO and 1800 HALO. The antitumor effect of treatment at 0000 HALO (early resting phase) group was significantly better with lower toxicity than the 1200 HALO (early activity phase) group, resulting in significantly longer survival (p < 0.05). In the clinical study, the effect of circadian rhythm-modulated 5-FU plus leucovorin therapy was evaluated in an end-stage patient with recurrent gastric carcinoma. After continuous weekly infusion of 5-FU (1000 mg/m2/day x 2) was stopped because of its gastrointestinal toxicity, circadian rhythm-modulated chemotherapy (CRMC) was performed changing the dose of 5-FU to 666 mg/m2/day during the daytime (0500 to 1700) and to 1333 mg/m2/day from evening to night (1700 to 0500). The patient persevered with the 23 CRMC course without any signs of severe side effects and survived for nearly a year, suggesting the potential effect of CRMC in minimizing toxicity and prolonging survival.
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A 58-year-old man was referred to our hospital because of painful swelling in the left lower leg and leukocytosis in January 1999. Moderate hepatosplenomegaly but no lymph node swelling was observed. Marked leukocytosis (leukocytes 44.9 x 10(4)/microliter with 95% morphologically prolymphocytes) and thrombocytopenia were detected. The surface phenotype of the leukemia cells was CD1-2+3+5+7+4+8+25+. Magnetic resonance imaging revealed dilated veins in the left lower leg. An abnormal 47XY, +22 karyotype was detected in 1/20 cells. Tests for HTLV-I antibody were negative. A diagnosis of T-cell prolymphocytic leukemia (T-PLL) was made on the basis of data including cytochemical and electron microscopic findings. Although 2 courses of chemotherapy comprising vincristine, cyclophosphamide, and prednisolone improved the venous thrombosis in the leg, the leukemia cells were refractory to chemotherapy. To prevent the recurrence of venous thrombosis due to leukostasis, the patient underwent repeated leukapheresis. The leukocyte count was maintained at around 20.0 x 10(4)/microliter after total 7 courses of leukapheresis, one course of which comprised 7l of extracorporeal circulation. In addition to the rare presentation of venous thrombosis, the CD4+8+25+ phenotype observed in this case is rare in patients with T-PLL.
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Clinical observations indicate that a proportion of patients with schizophrenia experience cognitive impairment, which suggests that a neurodegenerative basis might be involved in the etiology of schizophrenia. Apolipoprotein E (ApoE), which has been confirmed to be genetically associated with Alzheimer's disease, is thus highlighted as a candidate gene for schizophrenia. Recently, novel functional polymorphisms in the ApoE transcriptional regulatory region have been found. To investigate whether these polymorphisms are associated with the risk of schizophrenia, we genotyped 144 patients with schizophrenia and 134 controls for two polymorphisms (-491A/T and -219G/T). No significant positive associations between both polymorphisms and schizophrenia were observed. Our findings exclude the regulatory region of the ApoE gene as a locus that might confer increased susceptibility to schizophrenia.
The biological functions of nitric oxide in the neuronal system remain controversial. Using a novel fluorescence indicator, DAF-2 DA, for direct detection of NO, we examined both acute rat brain slices and organotypic culture of brain slices to ascertain NO production sites. The fluorescence intensity in the CA1 region of the hippocampus was augmented, especially after stimulation with NMDA, in acute brain slices. This NO production in the CA1 region was also confirmed in cultured hippocampus. This is the first direct evidence of NO production in the CA1 region. There were also fluorescent cells in the cerebral cortex after stimulation with NMDA. Imaging techniques using DAF-2 DA should be very useful for the clarification of neuronal NO functions.
Previous studies have shown that many neuroleptics are metabolized by debrisoquine 4-hydrolase (CYP2D6), which exhibits genetic polymorphisms. In Oriental populations, poor metabolizers (PMs) with a lack of CYP2D6 activity are rare, although the CYP2D6*10 allele, which is associated with decreased CYP2D6 activity, is commonly found. The authors examined the relationship between tardive dyskinesia (TD) and CYP2D6 polymorphisms, including the CYP2D6*10 allele. Subjects consisted of 100 Japanese schizophrenics. TD was evaluated using the Abnormal Involuntary Movement Scale (AIMS). Genotyping for the presence of the CYP2D6*3, CYP2D6*4 and CYP2D6*10 alleles was performed using allele-specific PCR amplification and endonuclease digestions. The frequency of the CYP2D6*10 allele was 0.52, and only one allele showed the PM genotype. There was a significant difference in the allelic distribution of CYP2D6*10 between subjects with and without TD. We also found significant genotypic and allelic associations with dichotomized total AIMS scores of 6 or more (moderate or severe abnormal movements) and with scores of less than 6 (mild or no movements). After these associations were adjusted for confounding variables (gender, age, duration of illness and neuroleptic dose) by regression analysis, the CYP2D6*10 genotype showed significant association with the total AIMS score, and a modest association with TD occurrence. These results indicate that the CYP2D6*10 genotype may play a role in the development of moderate or severe abnormal movements.
Acquired multidrug resistance to anti-cancer agents has been associated with overexpression of the P-glycoprotein and other members of the ATP-binding cassette superfamily. The present studies demonstrate that SCC-25 cells selected for resistance to the alkylating agent cisplatin (CDDP) overexpress the anti-apoptotic Bcl-xL protein. In contrast to parental cells, the SCC-25/CDDP-resistant variant failed to exhibit activation of caspase-3, cleavage of protein kinase C delta, and other characteristics of apoptosis in response to CDDP. Similar results were obtained when SCC-25/CDDP cells were exposed to the structurally and functionally unrelated antimetabolite 1-beta-D-arabinofuranosyl-cytosine (ara-C). Other cells selected for resistance to doxorubicin or vincristine also exhibited overexpression of Bcl-xL and failed to respond to CDDP and ara-C with activation of caspase-3. The results further demonstrate that multidrug-resistant cells exhibit a block in the release of mitochondrial cytochrome c into the cytosol and that this effect is dependent on overexpression of Bcl-xL. The demonstration that lysates from the resistant cells respond to the addition of cytochrome c with activation of caspase-3 confirms that the block in apoptosis is because of inhibition of mitochondrial cytochrome c release. These findings demonstrate that cells respond to diverse classes of anti-cancer drugs with overexpression of Bcl-xL and that this response represents another mechanism of acquired multidrug resistance.
Nitric oxide is a gaseous, free radical which plays a role as an intracellular second messenger and a diffusable intercellular messenger. To obtain direct evidence for NO functions in vivo, we have designed and synthesized diaminofluoresceins (DAFs) as novel fluorescent indicators for NO. The fluorescent chemical transformation of DAFs is based on the reactivity of the aromatic vicinal diamines with NO in the presence of dioxygen. The N-nitrosation of DAFs, yielding the highly green-fluorescent triazole form, offers the advantages of specificity, sensitivity, and a simple protocol for the direct detection of NO (detection limit 5 nM). The fluorescence quantum efficiencies are increased more than 100 times after the transformation of DAFs by NO. Fluorescence detection with visible light excitation and high sensitivity enabled the practical assay of NO production in living cells. Membrane-permeable DAF-2 diacetate (DAF-2 DA) can be used for real-time bioimaging of NO with fine temporal and spatial resolution. The dye was loaded into activated rat aortic smooth muscle cells, where the ester bonds are hydrolyzed by intracellular esterase, generating DAF-2. The fluorescence in the cells increased in a NO concentration-dependent manner.
To perform the complex manipulation of the adenoviral genome for the construction of recombinant adenovirus vectors, we developed a cosmid vector (pacad1A) from which an infectious E1 and E3-deleted adenoviral genome can be released with PacI digestion. The cosmid vector, pacad1A, has unique restriction enzyme sites that are created for the insertion of foreign genes into the deleted E1 or E3 region of the adenoviral genome. To demonstrate the feasibility of the construction of adenovirus vectors with our developed vector, we showed that a recombinant adenovirus bearing a self-contained tetracycline-regulated expression system could be generated by transfection of cells with an infectious adenoviral genome that was released from pacad1A-derived plasmid DNA. The recombinant adenovirus vector was obtained easily by this method, and the expression of a transgene was proved to be regulated with tetracycline in CHO-K1 cells.
Tec is a non-receptor type tyrosine kinase which is tyrosine phosphorylated and activated upon stimulation of hematopoietic cells with various cytokines. The role of Tec in G protein-coupled receptor- and integrin-mediated signalings has not been elucidated. We therefore investigated the regulation of Tec in human blood platelets. Tec was rapidly tyrosine phosphorylated in response to platelet agonists which activate G protein-coupled receptors such as thromboxane A2 analog (U46619), thrombin, and thrombin receptor activating peptide (TRAP). TRAP-induced phosphorylation in Tec was significantly reduced under the conditions which abrogate fibrinogen binding to GP IIb-IIIa and subsequent platelet aggregation. However, TRAP induced significant levels of the phosphorylation even under these conditions and also in thrombasthenic platelets which lack functional GP IIb-IIIa molecules, suggesting that activation of G-protein-coupled receptor causes the phosphorylation. To clarify whether integrin engagement by itself causes the phosphorylation in Tec, we examined the state of the phosphorylation in platelets activated by integrin engagement. Platelet adhesion to immobilized fibrinogen or collagen induced significant levels of the phosphorylation. Furthermore, Tec was translocated to cytoskeleton in response to TRAP in a manner dependent on platelet aggregation, suggesting that Tec can be a component of integrin-mediated signalings. These results collectively indicate that Tec is involved in G protein-coupled receptor- and integrin-mediated signalings in human blood platelets.
The measurement of nitric oxide (NO) is important for direct examination of the regulatory roles of NO in various biological systems. Diaminofluoresceins (DAFs), new fluorescence indicators for NO, were applied to detect the release of NO from bovine aortic endothelial cells (ECs). DAFs react with NO to yield the corresponding green-fluorescent triazolofluoresceins, which provide the advantages of specificity, sensitivity and a simple protocol for the direct detection of NO. Using these DAFs, we could detect the generation of NO not only from inducible NO synthase expressed in macrophages, but also from constitutive NO synthase expressed in ECs.
Intratumoral inoculation of replication-competent, attenuated herpes simplex virus (HSV) mutants inhibits tumor growth by direct cytotoxic viral replication and induction of a tumor-specific immune response. To boost the antitumor response, we describe a defective HSV vector encoding IL-12 as an adjuvant to in situ vaccination by the replication-competent HSV helper virus. The defective HSV vector system consists of defective particles containing tandem repeats of the cytokine genes (p40 and p35) in combination with a HSV helper virus. Heterodimeric IL-12 was expressed and secreted after IL-12 defective vector infection of tumor cells. In a syngeneic, bilateral established tumor model with CT26 murine colon carcinoma, unilateral intratumoral inoculation with an IL-12 defective/replication-competent HSV vector combination significantly reduced tumor growth of the inoculated and noninoculated contralateral tumors. This antitumor effect was significantly greater than with a lacZ-defective/replication-competent HSV vector combination, which itself was significantly greater than the mock inoculation. Efficacy is associated with enhancement of tumor-specific CTL activity, including specificity against the CT26 immunodominant MHC class I restricted Ag AH1, and IFN-gamma production. There was no significant tumor growth inhibition after intratumoral inoculation of s.c. CT26 tumors in athymic mice. We conclude that this defective HSV vector system is an effective method for cytokine gene delivery to tumors in situ and IL-12 expression in tumors synergizes the antitumor activity mediated by the replication-competent HSV helper virus.
Two hours after its addition to cultures of a guinea pig cell line, 104C1, dilinoleoyl phosphatidylcholine monohydroperoxide (PCOOH) at concentrations of 5-160 microM induced a dissipation of the mitochondrial inner membrane potential (delta psi m), without any apparent morphological changes, in the cells. The PCOOH-induced loss of delta psi m was restored 4 hr after the replacement of the medium with PCOOH-free fresh medium. In contrast, 104C1/O4C cells, a stable clone from 104C1 cells transfected with the human phospholipid hydroperoxide glutathione peroxidase (PHGPx) gene encoding a sequence including a signal peptide towards mitochondria, were resistant to the loss of delta psi m after a 2-hr exposure to PCOOH at concentrations up to 160 microM. Even after an 8-hr exposure to 80 microM PCOOH, the transfected cells retained their delta psi m intact, though the parent cells were killed by the same treatment. The present results strongly suggest that the expression of PHGPx protected the host cells from PCOOH-mediated injury at least by protecting their mitochondria from lipid hydroperoxide-induced loss of delta psi m.
The pleiotropic biological activities of interleukin-18 (IL-18) are mediated by IL-18 receptor (IL-18R). When the ligand binds to the IL-18R, IL-18R initiates a signaling cascade that results in the activation of nuclear factor kappa B (NF-kappa B). When mouse EL-4 cells were exposed to IL-18, IL-1 receptor-associated kinase (IRAK) was recruited to IL-18R and was phosphorylated. In addition, tumor necrosis factor receptor-associated factor-6 (TRAF6) was associated with IRAK. Therefore, we concluded that IL-18/IL-18R-mediated signaling may share the IRAK/TRAF6 pathway through NF-kappa B activation with the IL-1/IL-1 receptor system.