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Biomedical subjects

M Naito

Publications and source records attributed to M Naito.

At least 343 records · Page 19Linked to original sources
PubMed1994

Characterization of newly established adriamycin resistant human leukemic cell lines (KY-ADR1 and KY-ADR2).

New adriamycin (ADR) resistant human leukemic cell lines (KY-ADR1 and KY-ADR2) have been established. KY-ADR1 was selected from a cytosine arabinoside (Ara C) resistant cell line by gradually increasing the concentration of ADR and KY-ADR2 from the parental cell line, KY-821, by the same method. The IC50s of both cell lines were 4.3 x 10(-5) and 3.6 x 10(-5) M ADR, respectively. Both lines revealed a similar cross resistance to various anticancer drugs, but KY-ADR1 was resistant to Ara C, whereas KY-ADR2 was sensitive. MDR1 gene was over-expressed and P-glycoprotein was expressed on the cytoplasmic membrane in both lines. Neither verapamil nor cyclosporin A could completely reverse ADR resistance. In addition, no significant changes in topoisomerase II and glutathione-s-transferase levels were detected. These findings indicate that ADR resistance in both cell lines is mainly mediated by P-glycoprotein and some other mechanism may be present. Interestingly, growth of both cell lines was stimulated by natural IL-1 and not affected by TNF alpha and IFN gamma, whereas growth of parental KY-821 was inhibited by these factors. These cell lines will provide new biological aspects on drug resistant leukemic cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Serial quantitative analysis of serum hepatitis C virus RNA level in patients with acute and chronic hepatitis C.

To examine changes in the serum level of hepatitis C virus RNA in acute and chronic phases of hepatitis C virus infection, we tested serial serum samples of six patients with acute hepatitis C (posttransfusion: three; sporadic: three) and 11 patients with chronic hepatitis C using a competitive reverse transcription and polymerase chain reaction assay. The internal standard consisted of known amounts of synthetic mutated RNA. No patient with acute hepatitis showed resolution during the follow-up period (24-57 weeks). In posttransfusion cases, titers of hepatitis C virus RNA (log10[hepatitis C virus RNA copies/ml serum]) rose to a high level (7.5-9.5) in the early phase of infection (4-12 weeks after the transfusions) in association with the first serum alanine aminotransferase peaks. Titers of hepatitis C virus RNA then decreased, while serum alanine aminotransferase levels fluctuated with multiple peaks. In sporadic cases, titers of hepatitis C virus RNA had already reached a high level (7.0-7.5) at the first alanine aminotransferase peaks 2-3 weeks after the clinical onset. In chronic hepatitis C virus infection, titers of hepatitis C virus RNA remained high for follow-up periods of 6-12 years in patients with chronic active hepatitis. These results indicate that the replication of hepatitis C virus rose to a high level in the early phase of infection and that a high replicative level of hepatitis C virus might be related with progression of liver disease in the chronic phase of infection.

Acute Disease↗
PubMed1994

Hepatitis C virus replication and antibodies to structural and nonstructural viral proteins in chronic hepatitis C.

The correlation between hepatitis C virus replication and antibodies to both structural (core) and nonstructural (C100-3) hepatitis C virus proteins (anti-HCVcore and anti-C100-3, respectively) was assessed. The concentration of serum hepatitis C virus RNA was determined by a competitive reverse transcription-polymerase chain reaction assay, and antibody titers were determined by endpoint dilution. No correlation was found between viremic levels and antibody titers in 42 chronic hepatitis C patients. At the end of a 6-month course of interferon-alpha therapy, 18 patients became negative for hepatitis C virus RNA. In the other 24 patients, post-treatment viremic levels ranged from 10(-6.5)-10(0.5) of pretreatment levels. Both anti-C100-3 and anti-HCVcore frequently decreased in patients whose viremic levels dropped to the negative range or to < 10(-2) of pretreatment levels. Anti-C100-3 decreased in all such cases (25/25), while anti-HCVcore decreased in 18/25 (72%) (p < 0.01), indicating that anti-C100-3 is more likely to decrease following suppression of viral replication than anti-HCVcore. These data suggest that hepatitis C virus antibodies may serve as a marker of suppression of viremia following interferon therapy even in patients who do not clear the virus.

Adult↗
PubMed1994

IgG and IgM core antibodies and viral replication in hepatitis C virus carriers.

We studied IgG and IgM antibodies to hepatitis C virus core protein (anti-HCVcore) in relation to serum virus RNA levels in 71 hepatitis C virus carriers. Viremic levels ranged from 10(4)-10(9) copies/ml and were high in 34 chronic active hepatitis patients compared with 17 asymptomatic carriers and 20 cases of chronic persistent hepatitis (p < 0.01). IgG anti-HCVcore was found in 67/71 (94%), but four asymptomatic carriers with low levels of viremia (10(4)-10(5.5) copies/ml) tested negative. IgM anti-HCVcore was found in patients with high levels of viremia (10(8)-10(9) copies/ml), and one (6%) asymptomatic carrier and nine (26%) chronic active hepatitis patients tested positive. In chronic hepatitis patients, viremic levels were significantly higher in cases positive for IgM anti-HCVcore than in negative ones (p < 0.01). However, no correlation was found between the occurrence of IgM anti-HCVcore and serum aminotransferase levels or the histologic activity index. These findings suggest that although IgG anti-HCVcore is sensitive, low viremic patients can escape this screening, and that the IgM anti-HCVcore is induced in association with high levels of virus replication.

Adult↗
PubMed1994

Cyclosporin A enhances susceptibility of multi-drug resistant human cancer cells to anti-P-glycoprotein antibody-dependent cytotoxicity of monocytes, but not of lymphocytes.

Cyclosporin A (CsA) was previously found to bind to P-glycoprotein expressed on multidrug-resistant (MDR) cancer cells. In the present study, the effect of CsA on anti-P-glycoprotein monoclonal antibody (mAb)-dependent cell-mediated cytotoxicity (ADCC) against human MDR cells was examined. The ADCC reaction was assessed by 4-h 51Cr-release assay. Highly purified lymphocytes (> 99%) and monocytes (> 99%) obtained from blood mononuclear cells (MNC) of healthy donors were used as effector cells. CsA decreased the cytotoxic activity of MNC against MDR cells, but enhanced their ADCC activity in the presence of anti-P-glycoprotein mAb MRK16. Lymphocyte-mediated ADCC and natural killer activity against MDR cells were also suppressed by addition of CsA. CsA induced a significant dose-dependent increase in monocyte-mediated ADCC activity. Interestingly, pretreatment of MDR cancer cells, but not of monocytes, with CsA significantly enhanced ADCC activity mediated by monocytes, but not by lymphocytes. A CsA analog (PSC833) and FK-506, but not verapamil also increased the sensitivity of MDR cells to ADCC by monocytes. CsA did not affect the binding of monocytes to MDR cells in the presence of MRK16 mAb. These results indicate that CsA may directly enhance the susceptibility of MDR cancer cells to the monocyte-mediated ADCC reaction.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Modulation of adriamycin resistance in human breast carcinoma MCF-7 cells in vitro and in vivo by medroxyprogesterone acetate.

The combination effect of adriamycin (ADM) and medroxyprogesterone acetate (MPA) was examined in vitro against human breast carcinoma MCF-7 and its ADM-resistant line (MCF-7/ADM). MCF-7 cells, which are positive for estrogen receptors, progesterone receptors and high-affinity MPA-binding activity, were more susceptible to the growth-inhibitory activity of ADM or MPA than MCF-7/ADM cells. A combination effect of ADM and MPA was observed against MCF-7/ADM cells, which are negative for steroid receptors, and furthermore against human nasopharynx carcinoma KB and its ADM-resistant line KB-A1. This combination effect of ADM and MPA against MCF-7/ADM cells was demonstrated to be synergistic by using the median effect plot method. The activity of MPA was almost equivalent to that of chlormadinone acetate or tamoxifen, greater than that of progesterone, and less than that of verapamil. The accumulation of ADM in MCF-7/ADM cells was enhanced by treatment with 10 microM MPA as well as 10 microM verapamil. The efflux of accumulated ADM from MCF-7/ADM cells was also partially inhibited by treatment with MPA or verapamil. MPA augmented the growth-inhibitory activity of ADM against MCF-7/ADM tumors inoculated into nude mice, although statistical significance was not observed. It is suggested that the clinical advantage of the combination of MPA with ADM against advanced breast cancers may be partly explained by the modulation of ADM resistance by MPA.

Animals↗
PubMed1994

Hepatitis C virus antibodies and virus replication in asymptomatic blood donors.

We assessed hepatitis C virus (HCV) infection in 99 asymptomatic blood donors positive using a first-generation HCV antibody assay. When tested with second-generation assays, 86 (87%) donors were reactive (group 1), 2 (2%) were indeterminate (group 2), and 11 (11%) were non-reactive (group 3). Viraemia was revealed by polymerase chain reaction in all group 1 cases. The 2 group 2 cases and 6 (55%) group 3 cases were also viraemic. Viraemia was confirmed by a branched DNA assay in the 2 group 2 cases and 4 (36%) group 3 cases. Serum HCV RNA levels were further studied using a competitive reverse transcription-polymerase chain reaction assay. All cases in groups 2 and 3 were low viraemic (range 10(4)-10(5.5) copies/ml) compared with the 9 group 1 cases examined (range 10(7)-10(9) copies/ml). No correlation was evident between viraemic levels and antibody cut-off index in the first-generation assay. These findings indicate the possibility that low levels of viraemia can occur in individuals non-reactive in second-generation HCV antibody assays.

Adult↗
PubMed1994

Peripheral carcinoid tumor of the lung with focal melanin production.

A case of carcinoid tumor of the lung with focal melanin production was encountered in a 56 year old Japanese woman. The tumor was found 16 years previously by mass survey chest X-ray and had enlarged two-fold in the intervening period. The tumor consisted of a variety of tumor cells showing a spindle, polygonal and pleomorphic appearance with abundant vasculature in the stroma. All tumor cells showed argyrophilia, together with a few showing argentaffinity. Melanin-containing tumor cells were also present in parts. Ultrastructurally, most tumor cells possessed various numbers of neurosecretory granules and a few of them contained granular type melanosomes. Tumor cells were connected with desmosomes and a few of them contained tonofilament-like microfilaments. Only a few contained both neurosecretory granules and melanin. By immunohistochemistry, serotonin, met-enkephalin and beta-endorphin positive cells were observed scattered throughout the tumor. A few tumor cells positive for tyrosine hydroxylase were also detected. Additionally, most tumor cells were positive for keratin. On the basis of these findings, the tumor of the current case is a pulmonary carcinoid tumor with focal melanin production.

Carcinoid Tumor↗
PubMed1994

Adult Chédiak-Higashi syndrome presenting as parkinsonism and dementia.

Chédiak-Higashi syndrome (CHS) in children can be a fatal disease. We describe the oldest known CHS patient first seen with a neurologic disorder in early adult life. From the age of 22, this 39-year-old woman developed mental deterioration, parkinsonism including resting tremor at the tongue, mandible, and hands, oculogyric crisis, muscular atrophy of limbs, and loss of tendon reflexes. MRI showed marked temporal dominant brain atrophy and diffuse spinal cord atrophy. Partial albinism, pan-leukocytic giant granules, and profoundly decreased NK-cell activity were compatible with childhood CHS, but apparently normal neutrophil function prolonged her survival. Stimulated proliferation of lymphocytes was less than 40% that of normal controls.

Adult↗
PubMed1994

Preservation of chick primordial germ cells in liquid nitrogen and subsequent production of viable offspring.

Conservation of genetic material in chickens was attempted by preserving primordial germ cells in liquid nitrogen. Primordial germ cells collected from the blood of embryos at stage 13-15 of White Leghorn and Barred Plymouth Rock breeds were concentrated by Ficoll density gradient centrifugation. The primordial germ cells were then suspended in a freezing medium containing 10% dimethyl sulfoxide. The temperature of the cell suspension was decreased by 1 degree C min-1 to -80 degrees C; the suspension was then placed in liquid nitrogen (-196 degrees C) and stored for 4-5 months. The cell suspension was thawed by taking it out of liquid nitrogen and placing it in water at 4 degrees C. The viability of the frozen-thawed primordial germ cells was 94.2%. One hundred frozen-thawed cells were injected into the bloodstream of recipient embryos (stage 14-15) from the other breed, from which blood had been drawn before the injection. These embryos were cultured in recipient eggshells until hatching. Viable offspring derived from the frozen-thawed primordial germ cells were obtained by mating male and female germline chimaeras or by mating the chimaeras with Barred Plymouth Rock chickens, and the offspring showed normal reproductive performance. This technique for cryopreservation of primordial germ cells giving rise to viable offspring makes it possible to conserve genetic material in avian species.

Animals↗
PubMed1994

Japanese family with a deficiency of lecithin:cholesterol acyltransferase (LCAT).

We present findings in the ninth known Japanese family with lecithin:cholesterol acyltransferase (LCAT) deficiency. A 54-year-old man (proband) and his 58-year-old brother presented with corneal opacity. Both subjects showed a marked decrease in serum high density lipoprotein (HDL)-cholesterol and in the cholesteryl ester ratio. Although apo A-I and A-II were low, apo E tended to be high. Serum LCAT activity and mass were not detectable. Urinary examination showed microhematuria or proteinuria. Renal function was normal and no anemia was demonstrated, but blood smears showed poikilocytosis with target cells. The serum LCAT activity of the proband's three sons, obligate heterozygotes of LCAT deficiency, was about one-half the normal level, and HDL-cholesterol and apo A-I levels were low normal.

Adult↗
PubMed1994

Increased serum hepatitis C virus RNA levels among alcoholic patients with chronic hepatitis C.

Hepatitis viruses and alcohol are major causes of liver disease. This study was aimed at investigating the effect of alcohol intake on the replication of hepatitis C virus and the efficacy of interferon therapy. Fifty-three patients who were histologically proved to have chronic hepatitis C were tested. Of these, 16 were diagnosed as habitual drinkers whose cumulative total consumption of alcohol was more than 100 kg or who had consumed at least 60 gm of ethanol daily for at least 5 yr. The quantities of hepatitis C virus RNA in serum were measured with a competitive assay that combined reverse transcription and polymerase chain reaction. The subjects received a 26-wk course of interferon-alpha therapy. There were no significant differences in age and ALT levels between habitual drinkers and nonhabitual drinkers. The titer of viral RNA (logarithmic transformed copy numbers per milliliter of serum) of habitual drinkers (8.5 +/- 0.5) was higher than that of nonhabitual drinkers (7.7 +/- 0.8) (p < 0.01). Neopterin levels in serum, a marker for the activation of cell-mediated immunity, were lower for habitual drinkers (5.7 +/- 1.5 pmol/ml) than for nonhabitual drinkers (8.1 +/- 5.0 pmol/ml) (p < 0.01). Eleven of the nonhabitual drinkers (30%) were long-term responders whose alanine aminotransferase levels remained within normal range during the 24 wk after interferon therapy, whereas only one (6%) of the habitual drinkers was a long-term responder (p = 0.06). These findings suggest that alcohol intake increases hepatitis C virus RNA levels in serum--at least in part--impairment of cellular immunity, and modulates the efficacy of interferon therapy.

Adult↗
PubMed1994

Enhanced expression by the brain matrix of P-glycoprotein in brain capillary endothelial cells.

P-glycoprotein (PGP), an active efflux pump of antitumor agents in multidrug-resistant tumor cells, exists in brain capillary endothelium and could be functionally involved in the blood-brain barrier. To study the regulatory mechanism of PGP expression in brain capillary endothelium, various mouse tissue matrices were tested for their abilities to enhance the expression of PGP in mouse brain capillary endothelial cells (MBEC), which express relatively small amounts of PGP. Of the four tissue matrices we examined, PGP expression in MBEC cultured on the brain matrix increased 2.0-fold. The PGP-inducing activity was similarly detected in bovine brain matrix, and the activity was enriched in the fraction of pl 9.0 by isoelectric focusing. The fraction, named PIC-fraction (PGP-inducing component), increased the PGP expression in MBEC 3.5-fold. By Northern blot analysis, a 3.3-fold enhancement of mdr gene expression was observed in MBEC cultured on the PIC-fraction. The PGP-inducing activity of the PIC-fraction was reduced by the treatment with trypsin but not with collagenase, suggesting that a proteinaceous factor distinct from type I collagen might be responsible for the PGP-inducing activity of PIC-fraction. Although the PIC-fraction increased the PGP expression in other mouse brain capillary endothelial cells, the PIC-fraction did not increase PGP expression in mouse aortic endothelial cells and KB carcinoma cell lines expressing various amounts of PGP. These observations suggest that PGP expression in brain capillary endothelium is specifically regulated by a tissue-specific factor in the brain matrix.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

[Enhancement of cellular accumulation of cyclosporine by anti-P-glycoprotein monoclonal antibody MRK-16, and their synergistic modulation of multidrug resistance].

Drug resistance is a major obstacle to successful cancer chemotherapy. P-glycoprotein, which transports various antitumor agents outside the resistant tumor cells, plays a key role in multidrug resistance. We found that MRK-16, a monoclonal antibody against P-glycoprotein, and cyclosporine, synergistically enhanced the antitumor effects of vincristine and adriamycin in multidrug-resistant K562/ADM cells. On the other hand, the combined use of MRK-16 with verapamil or FK-506 did not show such synergistic effects. Drug accumulation studies revealed that MRK-16 remarkably increased the accumulation of cyclosporine, but not verapamil, in K562/ADM cells. This increased accumulation of cyclosporine by MRK-16 in K562/ADM cells directly resulted in the enhanced accumulation of vincristine and adriamycin in the cells. The synergistic effect of MRK-16 and cyclosporine was further confirmed by isobologram analysis in three different highly multidrug-resistant tumor cells. Moreover, while MRK-16 alone did not enhance the sensitivity of the KB-8-5 cells moderately resistant to vincristine, it increased two-fold the reversing effect of cyclosporine at 1 microM, an achievable blood concentration. Since MRK-16 alone showed therapeutic effects against multidrug-resistant tumors, the combined use of MRK-16, cyclosporine and antitumor agents would provide therapeutic benefits for the treatment of resistant tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Endocytic pathway of scavenger receptors via trans-Golgi system in bovine alveolar macrophages.

BACKGROUND: The scavenger receptors are trimeric membrane glycoproteins present on the surface membrane of macrophages and macrophage-derived foam cells and are implicated in the deposition of cholesterol in the arterial walls during atherogenesis. This receptor mediates endocytosis of a diverse alley of negatively charged macromolecules including modified low density lipoproteins. EXPERIMENTAL DESIGN: We tried biochemical and morphologic approaches to elucidate in more detail the endocytic and intracellular pathway of the scavenger receptors during endocytosis of acetylated low density lipoproteins (AcLDL) and oxidized LDL (OxLDL) by bovine alveolar macrophages. Biochemically, cell interaction and subsequent intracellular degradation of AcLDL and OxLDL were examined using [125I]AcLDL or [125I]OxLDL. At the ultramorphologic level, the scavenger receptors were detected by a mouse monoclonal antibody against bovine macrophages, D2, with colloidal gold particles (AcLDL-Au or OxLDL-Au particles) as tracer of ligands. RESULTS: The biochemical studies demonstrated that after binding of AcLDL and OxLDL to the cell surface, these ligands were internalized and degraded intracellularly. Immunoelectron microscopy revealed that after a 2-hour incubation at 4 degrees C AcLDL-Au or OxLDL-Au particles were bound to the scavenger receptors present on the cell surfaces. Upon a temperature shift from 4 to 37 degrees C, these particles were concentrated in coated pits and internalized in endosomes. After subsequent dissociation of the particles from the receptors within the endosomes, the ligands were transported to secondary lysosomes, the receptors were transported to a trans-Golgi system. In the Golgi complex, the receptors were packed in secretory vesicles and recycled to the cell surface membrane. The transport and recycling of the receptors via the trans-Golgi system were completely inhibited by incubation below 18 degrees C or pretreatment with monensin. CONCLUSIONS: These results suggest that during endocytosis of modified low density lipoprotein, the Golgi complex plays a crucial role in sorting and recycling of the scavenger receptors in macrophages.

Animals↗
PubMed1994

Hepatitis B virus carrier with low titer of antibody to hepatitis B core antigen.

Of 798 hepatitis B virus (HBV) carriers, 22 had low titers (lower than 80% inhibition in 200- or 400-fold diluted serum) of antibody to hepatitis B core antigen (anti-HBc). Among these 22 patients, there were 12 (1.50%) with viremia who were positive for hepatitis B e antigen and had a high titer of HBV-associated DNA polymerase activity. Among these 12 patients, four showed no significant change in the anti-HBc titer, while four others showed significant increases in the anti-HBc titer during the follow-up periods. The former all remained asymptomatic carriers (ASCs), while the latter all developed chronic hepatitis (CH). The liver histology of four patients (ASC: 2, CH: 2) showed mild inflammation, and the localization of hepatitis B core antigen (HBcAg) in the liver specimens showed a nuclear pattern in the two ASCs, but a nuclear plus cytoplasmic pattern in the two CH cases. In HBV carriers, the increase in anti-HBc titer seems to be closely correlated to the change in HBcAg localization from the nucleus to the cytoplasm in the liver. Therefore, rising titers of anti-HBc were assumed to be associated with increased expression of HBcAg on the hepatocyte, and hence increased immune-mediated hepatic damage and the onset of hepatitis in ASC with low titer of anti-HBc.

Adolescent↗