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Biomedical subjects

M Kurita

Publications and source records attributed to M Kurita.

At least 19 recordsLinked to original sources
PubMed2004

Agrobacterium tumefaciens-mediated transformation of embryogenic tissue and transgenic plant regeneration in Chamaecyparis obtusa Sieb. et Zucc.

A genetic transformation procedure for Chamaecyparis obtusa was developed after co-cultivation of embryogenic tissues with disarmed Agrobacterium tumefaciens strain C58/pMP90, which harbours the sgfp (synthetic green fluorescent protein) visual reporter and nptII (neomycin phoshotransferase II) selectable marker genes. The highest transformation frequency was 22.5 independent transformed lines per dish (250 mg embryogenic tissue) following selection on kanamycin medium. Transgenic plantlets were regenerated through the maturation and germination of somatic embryos. The intensity of GFP fluorescence, observed under a fluorescence microscope, varied from very faint to relatively strong, depending on the transgenic line or part of the transgenic plant. The integration of the genes into the genome of regenerated plantlets was confirmed by Southern blot analysis.

Agrobacterium tumefaciens↗
PubMed2004

Somatic embryogenesis and plant regeneration from immature zygotic embryos of Hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.).

We established a plant regeneration system for Hinoki cypress (Chamaecyparis obtusa) via somatic embryogenesis. Embryogenic tissues were successfully induced on three kinds of Smith media from megagametophyte explants containing pre-cotyledonary embryos of C. obtusa plus-trees. Factors affecting somatic embryo maturation were examined. The concentration of polyethylene glycol 4000 in the medium was a critical factor for embryo maturation and its effective concentration was 150 g/l. The addition of 30 g/l maltose to the medium had a positive effect on embryo maturation, but sucrose was ineffective. The mature somatic embryos germinated at a germination frequency of approximately 60%, and the presence of activated charcoal was effective in stimulating plantlet growth. The plantlets acclimatized successfully in a greenhouse. To our knowledge, this is first report describing details of a plant regeneration method for C. obtusa via somatic embryogenesis.

Cell Culture Techniques↗
PubMed2001

Evaluation of waste pyrolysis characteristics in a pressurized fluidized bed reactor.

To obtain the distribution of fuel components to gas, tar and char in a pressurized fluidized bed waste pyrolyzer, experiments were conducted with a laboratory scale fluidized bed reactor. Waste samples were fed batchwise from the top of the reactor into the fluidized bed of silica sand and pyrolyzed by nitrogen/nitrogen-O2 gas and the effects of pressure, particle size, heating rate and oxygen addition were investigated. In the case of rubber, the char yield tended to increase a little and the tar yield decrease over the pressure of 304-709 kPa. In comparison with the thermogravimetry data it was clearly demonstrated that the char yield from fluidized bed pyrolysis is much lower. A small amount of oxygen addition decreased both tar and char yields but its further increase did not affect them very much.

Air Pollution↗
PubMed2001

A new technique for monitoring the behaviour of free-ranging Adélie penguins.

Measurement of the time allocation of penguins at sea has been a major goal of researchers in recent years. Until now, however, no equipment has been available that would allow measurement of the aquatic and terrestrial behaviour of an Antarctic penguin while it is commuting between the colony and the foraging grounds. A new motion detector, based on the measurement of acceleration, has been used here in addition to current methods of inferring behaviour using data loggers that monitor depth and speed. We present data on the time allocation of Adélie penguins (Pygoscelis adeliae) according to the different types of behaviours they display during their foraging trips: walking, tobogganing, standing on land, lying on land, resting at the water surface, porpoising and diving. To illustrate the potential of this new technique, we compared the behaviour of Adélie penguins during the chick-rearing period in a fast sea-ice region and an ice-free region. The proportion of time spent standing, lying on land and walking during foraging trips was greater for penguins in the sea-ice region (37.6+/-13.3% standing, 21.6+/-15.6% lying and 5.9+/-6.3% walking) than for those in the ice-free region (12.0+/-15.8 % standing, 0.38+/-0.60% lying and 0 % walking), whereas the proportion of time spent resting at the water surface and porpoising was greater for birds in the ice-free region (38.1+/-6.4% resting and 1.1+/-1.1% porpoising) than for those in the sea-ice region (3.0+/-2.3% resting and 0% porpoising; means +/- s.d., N=7 for the sea-ice region, N=4 for the ice-free region). Using this new approach, further studies combining the monitoring of marine resources in different Antarctic sites and the measurement of the energy expenditure of foraging penguins, e.g. using heart rates, will constitute a powerful tool for investigating the effects of environmental conditions on their foraging strategy. This technique will expand our ability to monitor many animals in the field.

Animals↗
PubMed2001

The masculinization of the fetus during pregnancy due to inhalation of diesel exhaust.

This study was conducted to determine the impact of diesel exhaust inhalation on the fetus. Seventy-two pregnant rats and 18 nonpregnant rats were divided into three groups: a group exposed to total diesel engine exhaust containing 5.63 mg/m(3) particulate matter, 4.10 ppm nitrogen dioxide, and 8.10 ppm nitrogen oxide; a group exposed to filtered exhaust without particulate matter; and a group exposed to clean air. The exposure period was from day 7 until day 20 of pregnancy. In addition, 15 pregnant rats were treated with aromatase inhibitors or testosterone to clarify the process by which diesel exhaust exerts its toxicity. The anogenital distance was significantly longer in male and female fetuses from both exhaust-exposed groups than in those of the control. Differentiation of the testis, ovary, and thymus was delayed and disturbed. Maternal testosterone and progesterone levels, which increased due to pregnancy whether or not the rats were exposed, were significantly higher and lower, respectively, in the pregnant rats exposed to total exhaust and filtered exhaust. The serum adrenocorticotropic hormone (ACTH) level and urinary excretion of 17-hydroxycorticosteroids (OHCS) did not differ among the pregnant groups. These results indicate that elevated testosterone did not result from elevated maternal adrenal function. The feto-placental-ovarian unit and inhibition of aromatase activity and synthesis caused by diesel exhaust inhalation might have played an essential role in the accumulation of testosterone. Since both exhaust-exposed groups showed almost the same reactions toward the inhalation, the gaseous phase must have included the relevant toxicants.

Adrenal Glands↗
PubMed2001

[Statistics on operations at the Department of Urology, Tatebayashi-Kosei Hospital during a ten-year period (June 1990-May 2000)].

A clinical statistic survey was made on the operations performed at the department of urology, Tatebayashi-Kosei Hospital between June 1990 and May 2000. The total number of operations was 2,680, consisting of 217 operations of the kidney, 126 operations of the ureter, 454 operations of the bladder, 1,354 operations of the prostate, 186 operations of the penis and ureter, 305 operations of the scrotum, 16 urologic operations performed by laparoscopy and 22 other operations.

Female↗
PubMed2000

Discrimination of histamine H1 and muscarinic receptor-mediated signalling pathways by phorbol ester in human astrocytoma cells.

1. Histamine H1 receptor-mediated signalling was compared with muscarinic receptor-mediated signalling in 1321N1 human astrocytoma cells. 2. Short-term (2 min) treatment of cells with phorbol 12-myristate 13-acetate (PMA) resulted in a reduction of increases in intracellular Ca2+ ([Ca2+]i) induced by carbachol or histamine. 3. Carbachol-induced increases in [Ca2+]i were 10-fold more sensitive to PMA than the histamine-induced increases. 4. When cells were treated with PMA for 48 or 72 h (long-term treatment), protein kinase C (PKC) was down-regulated and PMA did not inhibit carbachol-induced increases in [Ca2+]i. 5. Histamine-induced increases in [Ca2+]i were significantly reduced by long-term treatment with PMA. 6. These findings suggest that the signalling pathways mediated by histamine H1 and muscarinic receptors can be distinguished by using PKC in 1321N1 human astrocytoma cells.

Astrocytoma↗
PubMed2000

Pathologic examination of renal cell cancer by means of step-sectioning.

BACKGROUND: Because incidental detection of small renal cell cancers (RCC) has recently become increasingly common, nephron-sparing surgery for these cases has been more widely performed. Renal cell cancer was investigated by means of step-sectioning in order to determine which cases were suitable for nephron-sparing surgery and how it should be performed. METHODS: Pathology specimens obtained from 90 cases of radical nephrectomy were examined in 5 mm sections. We excluded large and invasive tumors from the present study. Particular attention was given to satellite tumor nodules (STN), pseudocapsules of the main tumor and vascular invasion. RESULTS: Satellite tumor nodules of cancer (STN-Ca) were found in seven of 90 cases (7.8%). Tumor size and grade was not correlated with the existence of STN-Ca. The distance between the main tumor and STN-Ca varied. with the pathology of the STN-Ca mostly resembling that of the main tumor. Pseudocapsules of the main tumor were incomplete in 53 cases (58.9%), but extracapsular invasion of more than 1 mm was not seen in tumors less than 50 mm in diameter. Through step-sectioning, a further six cases with microscopic vascular invasion were found. Vascular invasion within the main tumor was confirmed in 16 of 17 cases (94.1%) and within normal renal tissue in only one case. CONCLUSIONS: The incidence of existing STN-Ca was not high (7.8%) in the present study, we had not any characteristics in the cases with STN-Ca. As STN-Ca were rarely near the main tumor, we could not expect to resect STN-Ca with main tumor, resection to more than 1 mm outside the pseudocapsule was needed for complete resection of main tumor less than 50 mm in diameter. Normal renal tissue between the tumor and pelvis is a requirement for selecting appropriate cases in nephron-sparing surgery, but we could not remove the risk of leaving STN-Ca completely.

Adenoma↗
PubMed2000

[A case of prostate cancer treated with combined androgen-blockade].

A 62-year-old man was admitted to our hospital because of urinary retention. A digital rectal examination revealed an enlarged, elastic, and hard prostate with an irregular surface. Prostatic biopsy was done and the pathological diagnosis was moderately differentiated adenocarcinoma. He was diagnosed as stage D2 by bone scan and MRI. We gave him 250 mg of fosfestrol intravenously for 13 days. Afterward, he underwent orchiectomy castrate and was given flutamide for two years. His condition has improved and he has experienced no relapse.

Adenocarcinoma↗
PubMed2000

[Statistics of the operations at the Department of Urology, Tone Chuo Hospital during a six-year period (June 1993-May 1999)].

A clinical statistic survey was made on the operations performed at the Department of Urology, Tone Chuo Hospital between June 1993 and May 1999. The total number of operations was 1296, consisting of 97 (7.5%) operations of the kidney, 67 (5.2%) operations of the ureter, 190 (14.7%) operations of the bladder, 454 (35.0%) operations of the prostate, 63 (4.9%) operations of the urethra, 92 (7.1%) operations of the penis, 149 (11.5%) operations of the scrotum and 184 (14.2%) other operations. With the aging society, the number of operations for those over 60 years old has exceeded 60%.

Adolescent↗
PubMed1999

Antibody-independent classical complement pathway activation and homologous C3 deposition in xeroderma pigmentosum cell lines.

Of human malignantly transformed cell lines, xeroderma pigmentosum (XP) cell lines were found to be highly susceptible to homologous complement (C): cells were opsonized by C3 fragments on incubation with diluted normal human serum. C3 fragment deposition on XP cells was Ca2+-dependent and occurred on live cells but not UV-irradiated apoptotic cells. (Ca2+ is required for activation of the classical C pathway via C1q and the lactin pathway via mannose binding lectin (MBL), and the surface of apoptotic cells usually activates the alternative C pathway.) In this study we tested which of the pathways participates in XP cell C3 deposition. In seven cell lines that allowed C3 deposition (i), Clq was shown to be essential but MBL played no role in C activation, (ii) Cls but not MASP bound XP cells for activation, (iii) no antibodies recognizing XP cells were required for homologous C3 deposition, and (iv) the alternative pathway barely participated in C3 deposition. Furthermore, the levels of C-regulatory proteins for host cell protection against C, decay-accelerating factor (DAF, CD55) and membrane cofactor protein (MCP, CD46), were found to be relatively low in almost all XP cell lines compared with normal cells. These results indicate that XP cells activate the classical C pathway in an antibody-independent manner through the expression of a molecule which directly attracts C1q in a C-activating form, and that relatively low levels of DAF and MCP on XP cells facilitate effective C3 deposition. The possible relationship between the pathogenesis of XP and our findings is discussed.

Antibodies↗
PubMed1999

Purification, characterization, and gene analysis of a chitosanase (ChoA) from Matsuebacter chitosanotabidus 3001.

The extracellular chitosanase (34,000 M(r)) produced by a novel gram-negative bacterium Matsuebacter chitosanotabidus 3001 was purified. The optimal pH of this chitosanase was 4.0, and the optimal temperature was between 30 and 40 degrees C. The purified chitosanase was most active on 90% deacetylated colloidal chitosan and glycol chitosan, both of which were hydrolyzed in an endosplitting manner, but this did not hydrolyze chitin, cellulose, or their derivatives. Among potential inhibitors, the purified chitosanase was only inhibited by Ag(+). Internal amino acid sequences of the purified chitosanase were obtained. A PCR fragment corresponding to one of these amino acid sequences was then used to screen a genomic library for the entire choA gene encoding chitosanase. Sequencing of the choA gene revealed an open reading frame encoding a 391-amino-acid protein. The N-terminal amino acid sequence had an excretion signal, but the sequence did not show any significant homology to other proteins, including known chitosanases. The 80-amino-acid excretion signal of ChoA fused to green fluorescent protein was functional in Escherichia coli. Taken together, these results suggest that we have identified a novel, previously unreported chitosanase.

Amino Acid Sequence↗
PubMed1999

Precise monitoring of porpoising behaviour of Adélie penguins determined using acceleration data loggers.

A new method using acceleration data loggers enabled us to measure the porpoising behaviour of Adélie penguins (Pygoscelis adeliae), defined as a continuous rapid swimming with rhythmic serial leaps. Previous hydrodynamic models suggested that leaping would be energetically cheaper when an animal swims continuously at depths of less than three maximum body diameters below the water surface. In the present study, free-ranging Adélie penguins leapt at a mean speed of 2.8 m s(-)(1) above the predicted threshold speed (0.18-1. 88 m s(-)(1)). Wild penguins reduced drag by swimming deeper (0.91 m) and did not swim continuously within the high-drag layer while submerged. This indicates that previous calculations may be incomplete. Moreover, leaps represented an average of only 3.8 % of the total distance travelled during the porpoising cycle, which would make energy savings marginal. Among the six penguins used in our study, two did not porpoise and three porpoised for less than 7 min, also indicating that this behaviour was not important during travel to and from foraging sites, as has been previously suggested. Birds mainly porpoised at the start and end of a trip. One explanation of porpoising might be an escape behaviour from predators.

Animals↗
PubMed1999

Purification, characterization and gene analysis of N-acetylglucosaminidase from Enterobacter sp. G-1.

Enterobacter sp. G-1 is a bacterium isolated previously as a chitinase-producing bacterium. We found this bacterium also produced N-acetylglucosaminidase and characterized that in this study. Extracellular N-acetylglucosaminidase of 92.0 kDa was purified near homogeneity by 8.57-fold from Enterobacter sp. G-1. The optimum temperature and the optimum pH of the purified N-acetylglucosaminidase was 45 degrees C and 6.0, respectively. The N-terminal amino acid sequence of 23 residues of N-acetylglucosaminidase was identified. Based on the N-terminal sequence, we amplified pieces of the DNA fragments by PCR. Using these PCR products as probes, we screened the genomic library and successfully isolated the entire N-acetylglucosaminidase gene (designated nag1) from Enterobacter sp. G-1. The nucleotide sequence of the nag1 gene was found to consist of 2,655 bp encoding a protein of 885 amino acid residues. Comparison of the deduced amino acid sequence from the nag1 gene found 97.3% identity with chitobiase from Serratia marcescens, 54.4% identity with N,N'-diacetylchitobiase from Vibrio harveyi, and 42.7% identity with N-acetylglucosaminidase (ExoI) from Vibrio furnissii. Enzymatic activity assay of N-acetylglucosaminidase indicated stronger activity toward PNP-GlcNAc than PNP-(GlcNAc)2 or PNP-(GlcNAc)3.

Acetylglucosaminidase↗
PubMed1998

Molecular cloning of membrane cofactor protein (MCP; CD46) on B95a cell, an Epstein-Barr virus-transformed marmoset B cell line: B95a-MCP is susceptible to infection by the CAM, but not the Nagahata strain of the measles virus.

Measles virus (MV) infects not only human beings but also some simian species. The MV receptor on Vero cells (a cell line established from African Green monkey kidney cells) and human cells has been shown to be the membrane cofactor protein MCP/CD46, which is an inhibitor of autologous complement (C) activation. B95a, an Epstein-Barr virus (EBV)-transformed marmoset B cell line, is a simian cell line used for MV selection and is much more susceptible to MV than Vero cells. In the present study, we isolated cDNAs encoding MCP homologues from B95a cDNA library and assessed whether B95a-MCP is responsible for the high susceptibility of B95a to MV. The deduced amino acid sequence of the cDNA of B95a-MCP was 76% identical to that of human-MCP, and the recombinant B95a-MCP exerts C inhibitor activity. Although CAM, a vaccine strain of MV, infected Chinese hamster ovary (CHO) cells expressing B95a-MCP, Nagahata strain, a wild type of MV, failed to infect the CHO transfectants, suggesting that additional membrane molecules of B95a are responsible for the high susceptibility of B95a to the Nagahata strain.

Amino Acid Sequence↗
PubMed1998

Moesin is not a receptor for measles virus entry into mouse embryonic stem cells.

The involvement of moesin in measles virus (MV) entry was investigated with moesin-positive and -negative mouse embryonic stem (ES) cells. MV infection of these cells was very ineffective and was independent of moesin expression. Furthermore, when these cells were transfected to express human CD46, a 100-fold increase in syncytium formation was observed with these cells and was independent of the expression of moesin. The only obvious difference between moesin-positive and -negative ES cells was the shape of the syncytia formed. Moesin-negative ES cells expressing or not expressing human CD46 formed separate pieces of fragmented syncytia which were torn apart during spreading, whereas ES cells expressing moesin exhibited typical syncytia. In addition, moesin was not detected on the surface of any murine cells or cell lines that we have tested by a flow cytometric assay with moesin-specific antibodies. These findings indicate that murine moesin is neither a receptor nor a CD46 coreceptor for MV entry into mouse ES cells. Moesin is involved in actin filament-plasma membrane interactions as a cross-linker, and it affects only the spreading and shape of MV-mediated syncytia.

Animals↗
PubMed1998

A wild-type Japanese measles virus strain inducing predominant early down-regulation of CD46.

Down-regulation of CD46 secondary to stimulation with measles virus (MV) was investigated using CD46-positive cell lines and Japanese wild-type MV strains. The cells used were simian cell lines B95a and Vero in which MV strains have been adapted to be amplified, and Chinese hamster ovary (CHO) cell transfectants expressing human CD46 with (CHO(tail+)) or without (CHO(tail-)) the cytoplasmic tail. Of four Vero-adapted and three B95a-adapted MV strains, one Vero-adapted strain named Khono (KO), down-regulated CD46 within 60 min (early down-regulation) in all cell lines examined except Vero. No strains other than Toyoshima (TY), which induced early down-regulation only in CHO(tail+) cells, induced early down-regulation of CD46 in any combination. On the other hand, conventional down-regulation of CD46 was observed 24 h post-MV inoculation (late down-regulation) when cell lines used were adapted to MV strains. Thus, we concluded that there are two modes of CD46 down-regulation by MV and the unique strain KO markedly induces early down-regulation. Also, the CD46 homologue of B95a, which fails to act as a MV receptor, is down-regulated concomitantly with MV replication (>24 h) in cells principally by competent virus strains.

Amino Acid Sequence↗