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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 163 records · Page 9Linked to original sources
PubMed1995

Diversity of sites for measles virus binding and for inactivation of complement C3b and C4b on membrane cofactor protein CD46.

The complement system membrane cofactor protein (MCP) CD46 serves as a C3b/C4b inactivating factor for the protection of host cells from autologous complement attack and as a receptor for measles virus (MV). MCP consists of four short consensus repeats (SCR) which are the predominant extracellular structural motif. In the present study, we determined which of the four SCR of MCP contribute to its function using Chinese hamster ovary cell clones expressing each SCR deletion mutants. The results were as follows: 1) SCR1 and SCR2 are mainly involved in MV binding and infection; 2) SCR2, SCR3, and SCR4 contribute to protect Chinese hamster ovary cells from human alternative complement pathway-mediated cytolysis; and 3) SCR2 and SCR3 are essential for protection of host cells from the classical complement pathway. These results on cell protective activity of the mutants against the human classical and the alternative complement pathways were compatible with factor I-mediated inactivation profiles of C4b and C3b, respectively, in the fluid-phase assay using solubilized mutants and factor I; the results were mostly consistent with those reported by Adams et al. (Adams, E. M., Brown, M. C., Nunge, M., Krych, M., and Atkinson, J. P. (1991) J. Immunol. 147, 3005-3011). SCR2 and SCR3 were required for C3b and C4b inactivation, and SCR4-deleted MCP showed weak cofactor activity for C4b cleavage but virtually no cofactor activity for C3b cleavage. The functional domains of MCP for the three natural ligands C3b, C4b, and MV, therefore, map to different, although partly overlapping, SCR domains.

Animals↗
PubMed1995

High-performance liquid chromatographic determination of diadenosine 5',5'"-p1,p4-tetraphosphate with precolumn fluorescence derivatization and its application to metabolism study in whole blood.

Diadenosine 5',5'"-p1,p4-tetraphosphate (Ap4A) was converted with chloroacetaldehyde to the fluorescent di-1,N6-ethenoadenosine derivative within 60 min at 80 degrees C. It was separated by reversed-phase HPLC and detected fluorimetrically (excitation and emission wavelengths of 275 and 410 nm, respectively). The detection limit of Ap4A was ca. 0.2 microgram/ml in plasma when 10 microliters of the sample was applied to the column. The rate of degradation of Ap4A added to whole blood (5 micrograms/ml) was examined using this method. Half-lives (means +/- S.E., n = 3) were 0.88 +/- 0.30 min (in rat blood), 13.7 +/- 3.6 min (in dog blood) and 17.2 +/- 1.4 min (in human blood). A marked species difference in the degradation rate of Ap4A in blood was observed.

Adenosine↗
PubMed1995

Fos induction in the medullary dorsal horn and C1 segment of the spinal cord by acute inflammation in aged rats.

In order to elucidate the effect of aging on nociceptive neurons in the central nervous system, c-fos was used as a marker of excitability of neurons in the medullary dorsal horn (MDH) and the first spinal segment (C1) following noxious stimulation of the lateral face of young and aged rats. The distribution of c-fos-positive cells was dense in the superficial laminae and sparse in the deep laminae of the MDH and C1 in both young and aged animals following subcutaneous injection of formalin into the lateral face, whereas few c-fos-positive cells were labeled after saline injection. The distribution of c-fos-positive cells in the superficial laminae of the aged rats was found to be denser and more rostro-caudally expanded compared to that in the young rats. C-fos-positive cells were distributed more rostro-caudally in aged than in young rats. There was no difference between young and aged rats in the distribution of c-fos-positive cells in the deep laminae. Substance P (SP), 5-HT and calcitonin gene-related peptide-like immunoreactive (CGRP-LI) fibers and varicosities showed similar distribution density in the MDH and C1. Furthermore, many 5-HT-LI aberrant fibers and varicosities were observed in the MDH and C1 of the aged rats. The SP-LI and CGRP-LI cells in the trigeminal ganglion of aged rats were larger than those of young rats. These findings suggest that a deficit of the descending 5-HT inhibitory system produces the increment of c-fos-positive cells in the MDH and C1 of aged rats, resulting in the recruitment of a larger number of neurons in the superficial laminae of the MDH and C1 for conveying nociceptive sensory information to the central nervous system.

Age Factors↗
PubMed1995

Effect of JTP-2942, a novel thyrotropin-releasing hormone analogue, on pentobarbital-induced anesthesia in rats.

The effects of a novel thyrotropin-releasing hormone (TRH) analogue, N alpha-((1S,2R)-2-methyl-4-oxocyclopentylcarbonyl)-L-histidyl-L-pro linamide monohydrate (JTP-2942), on pentobarbital-induced anesthesia in rats were investigated and compared with those of TRH. Intravenous administration of both JTP-2942 and TRH caused a dose-dependent decrease in the recovery time from pentobarbital-induced anesthesia. The minimum effective doses of JTP-2942 and TRH were respectively 0.03 and 1 mg/kg. The effect of JTP-2942 was antagonized by intraperitoneal scopolamine (0.5 mg/kg). Intraperitoneal JTP-2942 (1 mg/kg) caused an increase of acetylcholine release and a decrease of choline release in the frontal cortex and hippocampus of pentobarbital-treated rats. In addition, JTP-2942 ameliorated the decrease of hemicholinium-3-sensitive high-affinity choline uptake and the increase of acetylcholine in these brain regions. However, JTP-2942 had no effect on choline acetyltransferase activity or the choline content, which were also not changed by pentobarbital. Our results indicate that the effect of JTP-2942 on pentobarbital-induced anesthesia was about 30 times more potent than that of TRH, and suggest that JTP-2942 may act by accelerating acetylcholine turnover.

Acetylcholine↗
PubMed1995

Arterial-injection chemotherapy for hepatocellular carcinoma using monodispersed poppy-seed oil microdroplets containing fine aqueous vesicles of epirubicin. Initial medical application of a membrane-emulsification technique.

BACKGROUND: Iodized poppy-seed oil (IPSO) has a property of depositing itself selectively in the cells of hepatocellular carcinoma (HCC). A mixture of anticancer agents and IPSO has been used widely because IPSO accumulates in tumors, but its usefulness appears limited because the anticancer agents become separated easily from IPSO and do not remain in the tumor. The authors prepared a long term inseparable, water-in-oil-in-water emulsion (W/O/W) for use in arterial-injection therapy for patients with HCC and evaluated its clinical usefulness. METHODS: The W/O/W was prepared by a membrane-emulsification technique using a controlled pore glass with 10.6-microns pores. From December 1992 to January 1994, the W/O/W containing 8-60 mg of epirubicin was applied to the hepatic arterial-injection therapy for 21 patients with HCC to determine its antitumor and side effects. RESULTS: After arterial infusions with W/O/W, an evident antitumor effect was observed in all 13 patients treated with W/O/W containing 40 mg or more of epirubicin with or without gelatin-sponge particles used simultaneously. In the group treated with the W/O/W containing a high dose (40 mg or more) of epirubicin, even though the gelatin-sponge particles were not used, tumor size was reduced in six of seven patients, and a 50% or greater decrease of initial alpha-fetoprotein (AFP) levels within 14 days was observed in all four patients who showed abnormal levels of serum AFP before treatment. One partial necrosis and two complete necroses of three resected tumors were confirmed histopathologically. Fever (in all patients), nausea (in two), pain in the right upper quadrant of the abdomen (in two), and slight cough (in one) were noted as minor side effects. CONCLUSIONS: To the authors' knowledge, this is the first clinical trial using this emulsion prepared by the membrane-emulsification technique. Emulsification using a fine-pore glass membrane of equal pore size (i.e., controlled-pore glass membrane) is a new technique for preparing lipid microdroplets of equal size (monodispersed) containing aqueous fine microdroplets to form W/O/W: This technique of chemoembolization can be used to treat patients with HCC.

Aged↗
PubMed1995

One-step sandwich enzyme immunoassays for human C4b-binding protein (C4BP) and protein S-C4BP complex using monoclonal antibodies.

C4b-binding protein (C4BP), a regulatory component in the complement system, binds to an anticoagulant vitamin K-dependent plasma protein S (PS) which acts as a cofactor of activated protein C. We raised monoclonal antibodies against C4BP and PS, and developed two different one-step sandwich enzyme immunoassay (EIA) systems for human total C4BP (assay A) and PS-C4BP complex (assay B) by using a solid phase monoclonal antibody and a horseradish peroxidase-labeled monoclonal antibody (Fab'). The reaction time of the assay was 45 min in both EIA systems: 30 min for the immunoreaction and 15 min for the color reaction. The sensitivities were 12 and 20 mg/l in assays A and B, respectively. Linearity was obtained between 31 and 500 mg/l in both EIA systems. Assay A could detect both uncomplexed C4BP and PS-C4BP complex with equal efficiency so that total C4BP level was not affected by PS. The levels of total C4BP and PS-C4BP complex were found to significantly increase in sera from patients with membranous nephropathy and decrease with liver cirrhosis in comparison with the levels in normal subjects. On the other hand, a difference in the total C4BP and PS-C4BP complex levels was not shown between IgA nephropathy and normal subjects. Affinity column analysis and difference of total C4BP and PS-C4BP complex levels showed that most of C4BP in sera exists as PS-C4BP complex.

Animals↗
PubMed1995

Interleukin-1 beta induction of tissue inhibitor of metalloproteinase (TIMP-1) is functionally antagonized by prostaglandin E2 in human synovial fibroblasts.

Elevated levels of tissue inhibitor of metalloproteases-1 (TIMP-1) have been demonstrated in inflamed synovial membranes, and it is believed that the inhibitor may play a critical role in the regulation of connective tissue degradation. The present study was undertaken to define the cellular mechanism of action of the inflammatory mediators, interleukin-1 beta (IL-1 beta) and prostaglandin E2 (PGE2), in the control of TIMP-1 synthesis and expression in human synovial fibroblasts. Recombinant human IL-1 beta induced a time- and dose-dependent saturable response in terms of TIMP-1 mRNA expression (effective concentration for 50% maximal response, EC50 = 31.5 +/- 3.3 pg/ml) and protein synthesis (EC50 = 30 +/- 3.3 pg/ml). The protein kinase C (PKC) inhibitors, H-7, staurosporine, and calphostin C, reversed the rhIL-1 beta induction of TIMP-1 mRNA. PGE2 also inhibited rhIL-1 beta-stimulated TIMP-1 mRNA expression and protein secretion in a dose-dependent fashion. The concentration of PGE2 necessary to block 50% of rhIL-1 beta-stimulated TIMP-1 secretion, IC50, was 1.93 ng/ml (4.89 nM). Forskolin, and other stable derivatives of cAMP, mimicked, to a large extent, the effects of PGE2. The phorbol ester, PMA, up-regulated considerably the mRNA expression of TIMP-1 but had no effect on protein production. Calphostin C substantially reduced PMA-activated TIMP-1 expression. Staurosporine, calphostin C, H-7, and substances that elevate cellular levels of cAMP, like PGE2, also reduced basal expression and synthesis of TIMP-1. Taken together, the data suggest that PKA and C may mediate opposing effects in terms of TIMP-1 expression and secretion in human synovial fibroblasts.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Endoscopic injection sclerotherapy for esophageal variceal hemorrhage in myeloproliferative disorder: case report.

A 70-year-old woman with myeloproliferative disorder and massive splenomegaly presented with hematemesis. Emergency endoscopy demonstrated bleeding from esophageal varices. Management of variceal hemorrhage by endoscopic injection sclerotherapy, using 5% ethanolamine oleate, was successful. Following the control of variceal bleeding, she was treated with hydroxyurea, a myelosuppressive agent. The spleen size markedly decreased and she was discharged 3 months later. Variceal hemorrhage in myeloproliferative disorder has been reported to be fatal on many occasions, despite different therapeutic approaches, including surgery. In this report, we demonstrated that endoscopic injection sclerotherapy followed by treatment with a myelosuppressive agent was effective in a patient with myeloproliferative disorder and variceal hemorrhage.

Aged↗
PubMed1995

Serum HCV RNA titer at the end of interferon therapy predicts the long-term outcome of treatment.

BACKGROUND/AIMS: Serum HCV RNA was quantitated by the competitive polymerase chain reaction before, at the end of, and after interferon therapy. We assessed whether serum HCV RNA titer at the end of interferon therapy predicts the long-term outcome of treatment. METHODS/RESULTS: Of 71 patients treated with various doses of interferons, 21 became negative for HCV RNA persistently during follow up of 2 years, and they were considered as complete responders. The serial determinations of HCV RNA titer for each individual showed that in patients with HCV RNA negative at the end of therapy, the complete response rate was quite high (78.6%), while in patients with HCV RNA titer > or = 10(4) copies/ml at the end of therapy, none became complete responders in long-term follow up. The percentage decreasing to < or = 10(2) copies/ml of HCV RNA at termination of interferon tended to be higher in patients with genotype 2a (14/21, 66.7%) than in those with genotype 1b (18/42, 42.9%). The complete response rate of patients whose viral load was < or = 10(2) copies/ml at termination of interferon was significantly higher in genotype 2a (11/14, 78.6%) than in genotype 1b (5/18, 27.8%) (p < 0.01). Pretreatment HCV RNA titer appeared to correlate to the titer at the end of therapy (r = 0.596, p < 0.001); even when HCV RNA decreased to < or = 10(2) copies/ml, the higher pretreatment titer indicated a lower likelihood of complete response (p < 0.05). CONCLUSIONS: These results indicate that HCV genotype and pretreatment viral titer are important factors in the response to interferon therapy. In addition, our study suggests that it is possible to stop interferon therapy at an appropriate time by monitoring HCV RNA titer.

Adult↗
PubMed1995

Interferon gamma production by peripheral blood lymphocytes to hepatitis C virus core protein in chronic hepatitis C infection.

Evidence suggests that cellular immunity to hepatitis C virus (HCV) core protein may be important in the pathogenesis of viral infection. Therefore, interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) derived from patients with chronic HCV infection (genotype 1b) was examined. The cellular immune response was evaluated with a recombinant HCV core fusion protein derived from a patient with genotype 1b. To identify the immunodominant epitopes, IFN-gamma production in responders was also assessed with a panel of nine synthetic peptides that covered the entire core region. It was found that mononuclear cells from 24 (52%) of 46 patients with chronic liver disease responded to the core protein; asymptomatic HCV carriers demonstrated a lower response rate (14%, P < .05). More important, individuals who had received IFN-alpha treatment and went into clinical and virological remission had a higher response rate (75%, P < .05) compared with those with ongoing hepatitis whose treatment failed (31%). Of 25 patients whose mononuclear cells responded to HCV core protein, 18 had a significant response to one or more peptides; 12 patients reacted to a peptide mixture containing hydrophilic sequences. The core peptide amino acid sequence 141 to 160 was recognized in 9 patients. Interestingly, 7 of 8 patients bearing HLA DR 4 and w53 haplotypes recognized the peptide sequence 141 to 160. Thus, IFN-gamma production of the mononuclear cell response appeared to be HLA DR restricted, and the responding cells were identified as CD4+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

HCV RNA monitoring for tailored regimens of interferon therapy in hepatitis C.

Sustained non-viraemia is prerequisite for a virological cure of hepatitis C virus (HCV) disease. We monitored serum HCV RNA in our patients during interferon therapy and for 6 months of follow-up. The rate of sustained responders (RNA-negative at the end of follow-up) differed significantly by whether or not RNA became sero-negative within 24 weeks of the initiation of therapy (71% vs 7%); and also by whether or not the RNA-seronegativity lasted for 12 weeks during therapy (88% vs 11%). Thus, by monitoring viraemia in individual patients, we can tailor the duration of therapy and minimize waste of interferon.

Follow-Up Studies↗
PubMed1995

Purification and functional properties of soluble forms of membrane cofactor protein (CD46) of complement: identification of forms increased in cancer patients' sera.

Normal human sera contained 10-60 ng/ml of soluble membrane cofactor protein (MCP, CD46) whereas sera of > 50% of the cancer patients contained > 60 ng/ml. MCP purified by immunoaffinity chromatography from both normal and cancer patients' sera consisted of three bands of 56, 47 and 29 kDa on SDS-PAGE/immunoblotting. The upper two components were increased in cancer patient sera. The 56 and 47 kDa soluble forms served as a cofactor for factor I-mediated cleavage of C3b. MCP expressed on Chinese hamster ovary (CHO) cells protects host cells from human C3 deposition and complement-mediated cytolysis, especially by activation of the alternative pathway. In this same assay system, exogenously added soluble MCP also protected untransfected CHO cells; however, its potency was much less than that of the endogenous membrane form. For example, 8 micrograms/ml of soluble MCP was equal to 10(4) copies/cell of the expressed MCP. Recombinant soluble forms possessed similar activity to the naturally occurring soluble forms and high doses (> 150 micrograms) blocked Arthus-like reaction induced in guinea-pigs by anti-Forssman antibody. These data establish that soluble forms of MCP are present in human sera that possess cofactor activity and their concentrations, especially the 56 and 47 kDa forms, are increased in sera of cancer patients. High doses of the recombinant soluble forms may be therapeutically useful for suppressing inflammatory responses.

Animals↗
PubMed1995

The precore/core promoter mutant (T1762A1764) of hepatitis B virus: clinical significance and an easy method for detection.

Recently, a new hepatitis B virus (HBV) mutant with HBe antigen-negative phenotype has been characterized, in which one TATA box-like motif of the precore/core promoter had degenerated: most frequently by both A-->T and G-->A mutations at positions 1762 and 1764, respectively. The clinical significance of this mutant is as yet unknown. In our present study, the T1762 A1764 mutant was sought in sera from HBV-infected blood donors and chronic liver disease patients by directly sequencing a PCR-amplified region of HBVDNA. Also, because the A1764 mutation generates a Sau3AI cleavage site (GGTC-->GATC), we digested the PCR products with Sau3AI to see if cleavage would occur at this specific site. Our results mostly corroborated the earlier report but we found a higher-than-predicted frequency of HBe antigen-positive blood donors positive for the mutant (22%). The titres of HBe antigen in these mutant-positive sera were slightly decreased compared to the titres in wild-type HBV infection. In addition, these blood donors had relatively high (though within the normal range) serum alanine aminotransferase (ALT) levels, suggesting that the T1762 A1764 mutation could be used as a sensitive laboratory marker for insidious hepatitis in these otherwise 'asymptomatic' carriers. The Sau3AI assay, which is much more convenient than sequencing, was shown to be useful for the detection of the T1762 A1764 mutant in an extensive number of clinical samples.

Alanine Transaminase↗
PubMed1995

Predictive factors in the response to interferon therapy in chronic hepatitis C.

Factors predicting the efficacy of interferon therapy were statistically analyzed on 111 patients with chronic hepatitis C. Of the treated patients (total doses of interferon; 96-468 MU), 35 (31.5%) had a long-term remission. On multivariate analysis, hepatitis C virus genotype (p < 0.0001), histological diagnosis (p < 0.05), fibrosis score of histological activity index (p < 0.01) and source of infection (p < 0.05) were found useful for predicting the response to interferon therapy. Our findings suggest that the outcome of interferon therapy can be predicted to some degree from pretreatment data, and that a new therapeutic strategy is necessary for the group of patients who are predicted to be nonresponders.

Adult↗
PubMed1995

Clearance of serum hepatitis C virus RNA after interferon therapy in relation to virus genotype.

The effect of recombinant interferon-alfa on serum HCV RNA levels in Japanese patients with chronic hepatitis C was investigated. At 24 weeks of treatment, 41 (32.5%) of 126 patients lost HCV RNA from serum, and aminotransferases were normalized in 31 (75.6%) of these 41 cases. HCV genotypes were categorized into four types (Type I, II, III, IV); the frequencies among the patients were: Type I: 0%, Type II: 70.6%, Type III: 20.6%, and Type IV: 6.3%. At the end of the 24-week treatment, HCV RNA levels were remarkably decreased in Type III patients and became undetectable in 18 (69.2%) of 26. In contrast, only 18 (20.2%) of 89 patients with Type II and two of eight with Type IV lost HCV RNA from sera. The relation between HCV genotype (Type III) and response to IFN therapy was also confirmed using a logistic regression model. HCV genotype seems to be an important factor in determining the response to IFN in patients with chronic hepatitis C.

Alanine Transaminase↗
PubMed1995

Quantitative immunoelectron microscopic analysis of the localization and induction of 25-hydroxyvitamin D3 24-hydroxylase in rat kidney.

25-Hydroxyvitamin D3 24(R)-hydroxylase (24-hydroxylase) is involved in the metabolism and regulation of vitamin D3 and is markedly induced by administration of vitamin D3. We detected this enzyme by electron microscopy and an immunogold technique along nephrons of normal and vitamin D3-administered rats. After the rats were administered vitamin D3, 50,000 IU/day for 1 week, they were perfusion-fixed with a paraformaldehyde solution. The fixed kidneys were then removed and embedded in LR White resin. Ultrathin sections were prepared and labeled by the immunogold technique using a mouse anti-rat 25-hydroxyvitamin D3 24-hydroxylase monoclonal antibody. We counted the number of gold particles bound per micron 2 of the mitochondria (particle density) of the tubule epithelial cells along the nephrons. In normal and vitamin D3-administered rats, gold particles were observed in the mitochondria of epithelial cells along the tubules. In normal rats, gold labeling for 24-hydroxylase was statistically significant (p < 0.05), in the S1-S2 segments, the S3 segment of the proximal tubules, and in the distal convoluted tubules. In the rats administered vitamin D3, the particle density increased significantly (p < 0.05) by about 12-fold in the S1-S2 segments of the proximal tubules, whereas it increased less markedly in other parts of the nephron. The marked induction of the S1-S2 segments of the proximal tubules suggests that these segments play an important role in the regulation of vitamin D3 metabolism.

Animals↗
PubMed1995

Quantitative cryoimmunogold electron microscopic studies on induction of serine: pyruvate aminotransferase in rat liver mitochondria by administration of glucagon.

Induction of mitochondrial serine: pyruvate aminotransferase (SPT) in rat liver by administration of glucagon was studied quantitatively by immunoblot analysis and cryoimmunogold electron microscopy. Immunoblot analysis revealed that two daily injections of glucagon produced marked increase of SPT protein mass to a level as much as 18 times that of the untreated rat. Cryoimmunogold electron microscopic analysis showed that the labeling density of the mitochondria increased in a parallel manner. Thus the induction of SPT analyzed by two methods showed an excellent correlation with a relative correlation coefficient of 0.98, indicating that the induction of SPT can be analyzed quantitatively by immunogold electron microscopy on cryoultrathin sections.

Animals↗