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Biomedical subjects

K Nakajima

Publications and source records attributed to K Nakajima.

At least 91 records · Page 5Linked to original sources

Highly diastereoselective dihydride formation by activation of methanol with IrCl((S)-binap)(PPh3).

Reaction of [IrCl((S)-binap)(PPh3)] ((S)-3) with methanol gave one of the diastereomers of the cis,mer-dihydride, cis,mer-OC-6-44-A-[IrCl(H2)((S)-binap)(PPh3)] ((S)-4a) stereoselectively, the structure of which was determined crystallographically, whereas the reaction of (S)-3 with H2 produced a 1:1 mixture of the diastereomers of the cis,mer-dihydride, (S)-4a and cis,mer-OC-6-44-C-[IrCl(H2)((S)-binap)(PPh3)] ((S)-4b).

Journal Article↗

Neurotrophin secretion from cultured microglia.

Because microglia have been suggested to produce neurotrophins, we tested this ability in vitro. Rat primary microglia were found to constitutively secrete a limited amount of brain-derived neurotrophic factor (BDNF), but nerve growth factor (NGF) and neurotrophin-3 (NT-3) were undetectable in the conditioned medium. Stimulation of the cells with lipopolysaccharide (LPS) increased BDNF secretion, and induced NGF secretion. As a first step to examine this regulation system, the association of protein kinase C (PKC) was pharmacologically analyzed. A PKC activator, phorbol-12-myristate-13-acetate, enhanced the secretion of BDNF. Pre-treatment of microglia with a PKC inhibitor, bisindolylmaleimide, suppressed LPS-stimulated BDNF secretion as well as the constitutive one. These results suggest that the PKC signaling cascade is closely associated with BDNF secretion. Among PKC isoforms, PKCalpha probably plays a role in BDNF secretion, based on the results of experiments using a specific PKC activator, 1-oleoyl-2-acetyl-sn-glycerol, and a specific PKC inhibitor, Gö 6976, and by immunoblotting. Taken together, these findings suggest that the secretion of BDNF from microglia is regulated through PKCalpha-associated signal transduction mechanism.

Animals↗

Simultaneous determination of selegiline-N-oxide, a new indicator for selegiline administration, and other metabolites in urine by high-performance liquid chromatography-electrospray ionization mass spectrometry.

In order to discriminate selegiline (SG) use from methamphetamine (MA) use, the urinary metabolites of SG users have been investigated using high-performance liquid chromatography (HPLC)-electrospray ionization mass spectrometry (HPLC-ESI-MS). Selegiline-N-oxide (SGO), a specific metabolite of SG, was for the first time detected in the urine, in addition to other metabolites MA, amphetamine (AP) and desmethylselegiline (DM-SG). A combination of a Sep-pak C18 cartridge for the solid-phase extraction, a semi-micro SCX column (1.5 mm I.D.x 150 mm) for HPLC separation and ESI-MS for detection provided a simple and sensitive procedure for the simultaneous determination of these analytes. Acetonitrile-10 mM ammonium formate buffer adjusted to pH 3.0 (70:30, v/v) at a flow-rate of 0.1 ml/min was found to be the most effective mobile phase. Linear calibration curves were obtained over the concentration range from 0.5 to 100 ng/ml for all the analytes by monitoring each protonated molecular ion in the selected ion monitoring (SIM) mode. The detection limits ranged from 0.1 to 0.5 ng/ml. Upon applying the scan mode, 10-20 ng/ml were the detection limits. Quantitative investigation utilizing this revealed that SGO was about three times more abundant (47 ng/ml, 79 ng/ml) than DM-SG in two SG users' urine samples tested here. This newly-detected, specific metabolite SGO was found to be an effective indicator for SG administration.

Chromatography, High Pressure Liquid↗

Ability of rat microglia to uptake extracellular glutamate.

Since it has been suggested that microglia in vivo act as glutamate scavengers, this possibility was investigated in primary cultured microglia. The microglia showed specific abilities to uptake (14)C-glutamate depending on incubation time and numbers of cells used. The activity was suppressed by a specific inhibitor for a glial cell-type transporter, glutamate transporter-1 (GLT-1) (EAAT2). However, that of cultured astrocytes was not affected. These results suggest that microglia uptake glutamate by means of GLT-1. Supporting these results, immunoblotting revealed the presence of GLT-1 in the microglia, while only glutamate-aspartate transporter (GLAST) (EAAT1: another glial cell-type transporter) was detected in the astrocytes. All together, these results indicate that microglia can act as glutamate scavengers in vivo by expressing the glutamate transporter GLT-1.

ATP-Binding Cassette Transporters↗

Protective immunity against influenza A virus induced by immunization with DNA plasmid containing influenza M gene.

DNA vaccination is characterized by its preferential induction of the cytotoxic T cell lymphocyte (CTL) response and is expected to be a useful means of protection against viral infection. We examined the protective effect of an expression plasmid (pME18S-M) containing M1 and M2 genes of influenza A/PR/8/34. We detected the CTL activity by introducing these plasmids into BALB/c mice by either the intramuscular or the intranasal route. The influenza-specific antibody response was also induced, although its neutralizing effect against influenza virus was not observed. From 70 to 80% protection was observed in the mice immunized with the pME18S-M plasmid followed by lethal infection with influenza viruses of the A/WSN/33 and A/PR/8/34 strains, whereas all mice without the plasmid vaccination failed to survive. This protective activity was significantly weakened when the CD8(+) cells of these immunized mice were eliminated by several injections of anti-CD8 antibody. The protective activity was also weakened when anti-CD4 antibody was injected in the early phase of DNA vaccination. These data suggest that the pME18S-M plasmid is useful as a DNA vaccine for overcoming highly mutational influenza viruses.

Amino Acid Sequence↗

The YXXQ motif in gp 130 is crucial for STAT3 phosphorylation at Ser727 through an H7-sensitive kinase pathway.

The signal transducer and activator of transcription (STAT) 3 is essential for mediating signals from the receptors for a variety of cytokines and growth factors, including IL-6 and EGF, and from cytoplasmic tyrosine kinases. Upon stimulation, STAT3 is phosphorylated at Ser727 and Tyr705. However, the role of phosphorylation at Ser727, and the kinase pathways responsible for this phosphorylation in IL-6 signaling remain obscure. Here we show that IL-6 activates at least two distinct STAT3 serine kinase pathways and that an H7-sensitive pathway is dominant over a PD98059-sensitive one in HepG2 cells stimulated with a low concentration of IL-6. The analysis, using a series of chimeric receptors containing the extracellular domain of the G-CSF receptor, the truncated form of gp 130, and additional short peptides at the gp 130 carboxy-terminus, showed that the YXXQ motif of gp 130 was sufficient for the H7-sensitive STAT3 Ser727 phosphorylation. This YXXQ-mediated pathway does not involve Erk, p38, JNK, or PKCdelta, and requires a site in the region from 533 to 711 of STAT3 for phosphorylation in vivo. Moreover, we show that Ser727 is required for full transcriptional activity of STAT3 for two different response elements. Thus, the YXXQ motif regulates STAT3 activities in two ways in response to even a low concentration of IL-6: it recruits STAT3 to the receptor for tyrosine phosphorylation, and activates an unidentified H7-sensitive pathway leading to the serine phosphorylation of STAT3.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Involvement of platelet-derived growth factor and histocompatibility of DRB 1 in chronic renal allograft nephropathy.

BACKGROUND: The role of activated T cells in graft arteriosclerosis, which is observed in chronic renal allograft nephropathy, and the involvement of major histocompatibility complex (MHC) incompatibility remain to be determined. We examined the effect of T lymphocytes that were obtained from renal transplant patients undergoing chronic rejection treated with cyclosporine (CsA) on platelet-derived growth factor (PDGF)-induced proliferation of cultured human vascular smooth muscle cells (SMC) and compared the proliferation activity of T lymphocytes with MHC incompatibility, especially DRB 1 mismatch. METHODS: Renal transplant patients with continued allograft function, who survived more than 1 year after transplantation, were recruited. Chronic rejection was documented by graft-biopsy findings together with increasing serum creatinine levels (10-20% per year). After the incubation of supernatant (conditioning medium) of cultured T cells from CsA-treated renal transplant patients with chronic rejection (n=18) and with normal renal function (n=14) as control, normal subjects (n=11) and chronic hemodialysis (HD) patients (n=5) with cultured SMC in the presence or absence of PDGF, DNA synthesis (3H-thymidine uptake) of SMC was examined. The in vitro effects of CsA on DNA synthesis of cultured SMC were also evaluated. RESULTS: The supernatant of cultured T cells from renal transplant patients with chronic rejection stimulated PDGF-induced DNA synthesis of SMC in a dose-dependent manner, showing significant enhancement as compared with control transplant patients, normal subjects, and chronic HD patients. The supernatant itself did not significantly stimulate DNA synthesis of SMC. No significant in vitro stimulation of CsA on DNA synthesis was observed. The supernatant of T cells obtained from recipients undergoing chronic rejection with two DRB 1 mismatches showed significantly higher enhanced activity of PDGF-induced DNA synthesis than the supernatant from those recipients without mismatch of DRB 1. On the other hand, no significant correlation of the enhanced activity by T cell supernatant to HLA A and B mismatch numbers was observed. CONCLUSIONS: Growth factor-promoting factors(s) derived from activated T cells associated with MHC class II DR expression, which promotes PDGF-induced proliferation of SMC, exists in renal transplant patients with chronic renal allograft nephropathy, and is probably involved in arteriosclerosis of the graft kidney.

Adult↗

Medical malpractice and legal resolution systems in Japan.

Medical malpractice claims and dispute resolution systems have been examined in Western societies for their impact on the quality of care and efficient compensation for injured patients. However, little is known about the Japanese malpractice environment because claim information has been closely guarded. Based on data from the Japanese Supreme Court, the Ministry of Health, Labor, and Welfare (formerly the Ministry of Health and Welfare), and the Japan Medical Association (JMA), which provides malpractice insurance to 43.5% of Japan's 250 000 physicians, we review Japanese malpractice liability systems and the frequency of claims during the last 30 years. Annual premiums for physician professional liability insurance are relatively low (454 dollars-491 dollars). Although the frequency of claims in Japan is lower than that reported in the United States, England, and Germany, the number of claims is increasing in Japan. According to publicly available data from the Japanese Supreme Court, the annual number of medical malpractice suits filed in district courts has increased from 102 in 1970 to 629 in 1998 (from 0.09 to 0.25 per 100 physicians). The proportion of awards greater than 89 dollars 300 increased from 13.6% in 1976 to 65.4% in 1987. Among JMA members, claims increased 31% from 1987 to 1999, but the frequency of claims has remained at approximately 0.3 per 100 JMA members. The JMA's professional liability program offers a nonbinding out-of-court review of claims that is faster and less expensive than judicial resolution (a few months with no attorney required vs 35 months and attorney fees), but is a poor means of deterrence or discipline. Since JMA data represent only 43.5% of Japanese physicians, generalizations cannot be made about all Japanese physicians and institutions. The lack of data on all claims hinders adequate evaluation of dispute resolution methods, development of appropriate risk management activities, and proactive education for Japanese physicians.

Insurance, Liability↗

Correlation between loose density and compactibility of granules prepared by various granulation methods.

The objectives of this study were to prepare the lactose granules by various granulation methods using polyethylene glycol 6000 (PEG 6000) as a binder and to evaluate the effects of granulation methods on the compressibility and compactibility of granules in tabletting. Lactose was granulated by seven granulation methods -- four wet granulations including wet massing granulation, wet high-speed mixer granulation, wet fluidized bed granulation and wet tumbling fluidized bed granulation; and three melt granulations including melt high-speed mixer granulation, melt fluidized bed granulation and melt tumbling fluidized bed granulation. The loose density, angle of repose, granule size distribution, mean diameter of granules, and the tensile strength and porosity of tablets were evaluated. The compactibilities of granules were varied by the granulation methods. However, the difference in compactibility of granules could not be explained due to the difference in compressibility, since there was no difference in Heckel plots due to granulation methods. Among their granule properties, the loose density of granules seemed to have a correlation with the tablet strength regardless of the granulation methods.

Chemistry, Pharmaceutical↗

Anharmonic effective pair potentials in CaTiO3, SrTiO3 and CaGeO3 perovskite.

The temperature dependence of EXAFS Debye-Waller factors in CaTiO3, SrTiO3 and CaGeO3 perovskite was investigated with the cumulant expansion method. The CaGeO3 perovskite as an analogue of the Earth's lower-mantle mineral was synthesized in a cubic anvil type apparatus under 10 GPa 1250 K The Ca, Ti and Ge K-edge EXAFS spectra were measured in transmission mode at temperature up to 1100 K The effective pair potentials, V(u)= alpha (u2/2+ beta u3/3!, were evaluated and the Grüneisen parameter were calculated. The potential coefficients alpha and beta for Ti-O bond in CaTiO3 are 6.9 eVA(-2) and -38 eVA(-3), respectively. Those for Ge-O bond in CaGeO3 are 9.8 eVA(-2) and -36 eVA(-3), respectively.

Journal Article↗

Apolipoprotein(a): structure and biology.

Apolipoprotein(a), apo(a), the distinctive glycoprotein constituent of lipoprotein(a), Lp(a), is synthesized in the liver, links covalently to apoB100-lipoprotein, and travels so linked in the plasma to tissue sites where removal mechanisms are yet undetermined. Depending on the redox status of the surrounding milieu, apo(a) may re-acquire its unbound state shown to have structural and functional properties different from those of the bound form. Apo(a) is potentially athero-thrombogenic, a property which may be influenced by its size, sequence polymorphism, type of lipoprotein it is linked to and the inflammatory state of the vessel wall. This set of variables must be taken into account when assessing the cardiovascular pathogenicity of free and bound apo(a).

Animals↗

Nitric oxide induces metallothionein (MT) gene expression apparently by displacing zinc bound to MT.

The metal binding protein metallothionein (MT) is involved in zinc homeostasis since it typically binds large amounts of zinc. Free zinc can control MT gene expression by interacting with metal-sensitive transcription factors. However, the precise factors governing intracellular release of metal ions from MT remain unknown. Aerobic nitric oxide (NO) can nitrosate thiol groups in proteins, and MT-bound cadmium is released by NO exposure. Thus, we hypothesized that NO may also be effective at displacing zinc from MT in cultured cells and that this could be an important physiological control mechanism in zinc homeostasis and utilization. In this study, DETA/NO, an agent that spontaneously generates NO with a 20-h half life in physiological media, was used to study the release of zinc from MT and the induction of MT in TRL1215 cells (a normal rat liver cell line). Zinc or cadmium was given at levels inducing MT production, followed by DETA/NO (20-200 microM) to produce controlled NO exposure in both cell lines. Although both metals activated MT gene expression, MT-I mRNA and MT protein were further increased when DETA/NO was given after zinc or cadmium treatment. Additionally, NO from DETA/NO clearly displaced MT-bound zinc, as evidenced by G-75 gel-filtration chromatography. The released zinc or cadmium probably then stimulates further MT gene expression. These results suggest that NO may play an important role in regulation of cellular zinc homeostasis by providing a controlled release mechanism for metal ions stored in MT, and NO-mediated release of MT-bound zinc could in turn activate gene expression, such as with the MT gene.

Animals↗

Predominance of genotype A HBV in an HBV-HIV-1 dually positive population compared with an HIV-1-negative counterpart in Japan.

Hepatitis B virus (HBV) has seven genotypes, A to G. Previous studies have shown that genotype C is the most prevalent strain in chronic HBV carriers in East Asia. This study was undertaken to investigate the epidemiology of HBV genotypes among Japanese patients who are coinfected with human immunodeficiency virus type 1 (HIV-1). The sequences of the complete hepatitis B surface antifen (HBsAg) genes were obtained from 18 coinfected Japanese patients. Among the 18 patients, 12 of 13 men who had sex with men (MSM) had genotype A (92%), whereas only one of five heterosexual or hemophiliac patients had genotype A. The predominance of genotype A HBV in MSM showed a striking contrast to the current genotype prevalence in the Japanese population. Owing to the recent decrease in the rate of vertical transmission in Japan, the role of sexual behavior in the transmission of HBV cannot be overestimated. Thus, the relative proportion of genotype A may gradually increase in Japan.

Adult↗

CpG methylation of promoter region inactivates E-cadherin gene in renal cell carcinoma.

CpG methylation in the promoter region has been shown to be important in the regulation of genes implicated in malignant transformation. The present study was designed to test the hypothesis that CpG methylation of the promoter region of the E-cadherin gene may inactivate its expression in renal cell carcinoma. To test this hypothesis, five kidney cancer cell lines and 34 microdissected renal cell carcinoma samples were analyzed for gene and protein expression by reverse transcription-polymerase chain reaction and immunohistochemistry, respectively. CpG methylation in the promoter regions of the E-cadherin gene was analyzed by the sodium bisulfite genome sequencing technique. Our results show that all normal renal tissue expressed the E-cadherin gene and protein. Of the renal cancer tissues analyzed, 67% (23 of 34) lacked E-cadherin expression, with an associated increase in methylation, compared with normal tissue. E-cadherin gene promoter was methylated in all renal cancer cell lines and was accompanied by a loss of E-cadherin gene and protein expression. The treatment of renal cancer cell lines with the demethylating agent 5-aza-2'-deoxycytidine restored E-cadherin mRNA expression in all renal cancer cell lines. This is the first report that shows inactivation of the E-cadherin gene and protein in renal cell carcinoma through CpG hypermethylation in the promoter region of this gene. The results of these experiments may contribute to an understanding of the role of E-cadherin inactivation in renal cell carcinoma.

Azacitidine↗

A case of double cancers with myocardial metastasis mimicking acute myocardial infarction both on an electrocardiogram and on Tc-99m-MIBI myocardial SPECT.

We report a rare case of double cancers with myocardial metastasis presenting acute myocardial infarction (AMI)-like findings both on an electrocardiogram (ECG) and on Tc-99m-MIBI myocardial SPECT. The ECG showed abnormal Q-waves and ST-segment elevation in leads V1-V4, and Tc-99m-MIBI SPECT showed a photon deficient area in the anteroseptum. These findings were suggestive of AMI, but the patient had been simultaneously suffering from two adenocarcinomas, which were lung cancer and gastric cancer, and consecutive ultrasonic cardiography (UCG) demonstrated a growing mass lesion in the septal aspect of the left ventricle. After a month he died of severe heart failure. The histological diagnosis of a specimen of the cardiac mass lesion was invasive adenocarcinoma infiltrating to the heart, which revealed that the myocardial metastasis had mimicked AMI. This case shows that it is difficult to distinguish between myocardial infarction and myocardial metastasis with myocardial perfusion SPECT. It is necessary to consider the possibility of myocardial metastasis when a patient with malignancy presents AMI-like findings.

Adenocarcinoma↗

Esophageal hypomotility in systemic sclerosis: close relationship with pulmonary involvement.

PURPOSE: Esophageal motility was assessed in patients with systemic sclerosis (SSc) by scintigraphy and compared with (i) extent of scleroderma, (ii) duration of disease, (iii) index of anti-topoisomerase I antibody (topo I), and (iv) pulmonary involvement. METHODS: A multiple-swallow test was performed in 47 patients with SSc in the supine position with 99mTc-DTPA. A region of interest on the entire esophagus was defined and the retention ratio (RR) was calculated from a time-activity curve. RESULTS: Patients with diffuse scleroderma had higher RRs than those with limited scleroderma (48.8% vs. 30.0%; p < 0.05). There was no correlation between the RRs and the duration of disease. Patients with positive topo I had higher RRs than those who were negative (53.8% vs. 29.7%; p < 0.05). Patients with reduced % diffusion capacity for carbon monoxide (%DLCO) had higher RRs than those with normal %DLCO (40.5% vs. 19.6%; p = 0.03). Patients with reduced % vital capacity (%VC) had higher RRs than those with normal %VC (54.6% vs. 25.0%; p < 0.005). Patients with pulmonary fibrosis had higher RRs than those who were negative (58.5% vs. 20.3%; p < 0.00005). CONCLUSION: Esophageal dysfunction in patients with SSc showed a correlation with the extent of scleroderma, positive topo I, and pulmonary involvement. The RR can be an objective clinical marker for the severity of organ fibrosis.

Adolescent↗