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Biomedical subjects

H Koyama

Publications and source records attributed to H Koyama.

At least 91 records · Page 5Linked to original sources
PubMed2000

Overexpression of mitochondrial citrate synthase in Arabidopsis thaliana improved growth on a phosphorus-limited soil.

The gene for mitochondrial citrate synthase (CS) was isolated from Daucus carota (DcCS) and introduced into Arabidopsis thaliana (strain WS) using Agrobacterium tumefaciens-mediated transformation. Characteristics of citrate excretion were compared between T3 transgenic plants, which were derived from the initial transgenic plants by self-fertilization and homozygous for DcCS, and the control plants that had no DcCS. The highest CS activity 0.78 micromol protein min(-1) exhibited by the transgenic plants was about threefold greater than that found in the control plants (0.23-0.28 micromol protein min(-1)). Western analysis of the transgenic plants showed two CS signals corresponding to signals obtained from both D. carota and A. thaliana. Thus, it appears that the CS polypeptides by ectopic expression of DcCS were processed into the mature form and localized in the mitochondria of A. thaliana. The signal corresponding to the mature form of DcCS were greater in the transgenic plants having higher levels of CS activity. When the transgenic plants were grown in Al-phosphate media, a correlation between the levels of CS activity and the amounts of citrate excreted into the medium. The highest value (5.1 nmol per plant) was about 2.5-fold greater than that from control plants (1.9 nmol per plant). Both growth and P accumulation were greater in transgenic plants with high CS activity than that in control plants when they were grown on an acid soil where the availability of phosphate was low due to the formation of Al-phosphate. It appears that the overexpression of CS in A. thaliana improves the growth in phosphorous limited soil as a result of enhanced citrate excretion from the roots.

Arabidopsis↗
PubMed2000

Prognostic significance of occult bone marrow micrometastases of breast cancer detected by quantitative polymerase chain reaction for cytokeratin 19 mRNA.

Amplification of cytokeratin 19 (CK19) transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) has been shown to be a highly sensitive assay for the detection of bone marrow micrometastases (BMM) of breast cancer, but recent studies have demonstrated the occurrence of false-positive results due to low-level, illegitimately transcribed CK19 in normal bone marrow tissue. One approach to solve this problem is to develop a quantitative CK19 RT-PCR assay and to introduce a cut-off value which can distinguish between illegitimate expression and cancer-specific expression levels. In the present paper, we describe a quantitative CK19 RT-PCR assay using a real-time automated PCR system. The number of CK19 transcripts was normalized to that of GAPDH transcripts as an internal control for quality and quantity of cDNA. The cut-off value for the ratio of CK19 to GAPDH transcripts was set at 10(-4) since the ratio never exceeded this value in the control bone marrow samples (n = 12). In total, 117 bone marrow aspirates from stage I - III patients with invasive breast cancers were subjected to CK19 RT-PCR assay and immunocytological examination. Forty (34.2%) were found to be BMM-positive by CK19 RT-PCR assay whereas only three (2.6%) were found to be BMM-positive by immunocytology. Multivariate analysis has shown that occult BMM detected by CK19 RT-PCR is a significant risk factor for relapse, being independent of axillary lymph node metastases.

Bone Marrow Neoplasms↗
PubMed2000

Quantitative analysis of bowel gas using plain abdominal radiograph in patients with irritable bowel syndrome.

OBJECTIVE: Ideally, the diagnosis of irritable bowel syndrome (IBS) would be achieved using a minimal number of procedures. It is presumed that bowel gas is related to IBS, and it is easily visualized by plain abdominal radiograph. In the present study, to clarify the relationship between IBS and the quantity of bowel gas, the measured bowel gas volume using plain abdominal radiographs was compared with the pathology of IBS. METHODS: Plain abdominal radiographs were digitized and transmitted to a computer (computed radiography) in 30 IBS patients and 30 normal controls. The quantity of bowel gas, determined as the pixel value on images and standardized by physique, was defined as the gas volume score (GVS). Using the mean +/- 2SD of GVS in the control group as the normal score, IBS patients were divided into three groups: high, normal, and low. To examine the sequential reproducibility of a similar quantity of bowel gas, a second plain abdominal radiography was performed about 2 months later, and the GVS were compared. The colonic transit time was determined using radiopaque markers. RESULTS: There was a strong correlation between the quantities of bowel gas measured by two independent gastroenterologists. The mean GVS of IBS patients was significantly higher than that in the control group (p < 0.001). The sequential reproducibility was recognized in all 10 IBS patients. There was no significance between colonic transit time and GVS, nor between symptoms and GVS. CONCLUSIONS: Abdominal gas was analyzed objectively by using GVS, and GVS was considered to represent a useful tool for the diagnosis of IBS.

Adult↗
PubMed2000

The extracellular matrix dynamically regulates smooth muscle cell responsiveness to PDGF.

Focal accumulation of smooth muscle (SMC) within the arterial intima contributes to the formation of lesions of atherosclerosis. Platelet-derived growth factor (PDGF) is a potent stimulant of SMC migration and proliferation in culture that may play a role in the accumulation of SMC in atherogenesis. SMCs normally reside in the media of the artery wall surrounded by extracellular matrix (ECM), including type I collagen. In atherogenesis, the ECM is degraded, new ECM components, such as fibronectin, are synthesized and assembled, and these alterations in ECM components are associated with changes in SMC phenotype. To model the changes in ECM in normal and diseased arteries, we have analyzed SMCs cultured on different forms of type I collagen. Our studies demonstrate that integrin-mediated signals from various forms of type I collagen lead to specific and rapid modulation of the integrin signaling complex, including cytoskeletal connections, and of the responsiveness of SMC to PDGF stimulation.

Animals↗
PubMed2000

Nitric oxide affects angiotensin II pressor response: possible mechanism of attenuated pressor response during pregnancy and etiology of pregnancy-induced hypertension.

OBJECTIVE: To investigate the mechanism of attenuated pressor responses to several vasoconstrictors during gestation, we sought to characterize the effects of N(G)-monomethyl-L-arginine (L-NMMA) and L-arginine (L-Arg) on the pressor response to the infusion of angiotensin II in rats. METHODS: L-NMMA and L-Arg were infused intraperitoneally into rats at a constant rate by means of an osmotic minipump. The L-NMMA group received an infusion of L-NMMA (3 mg/day) daily for 13 days, whereas the L-NMMA plus L-Arg group received L-NMMA (3 mg/day) daily for 4 days, followed by L-NMMA plus L-Arg (12 mg/day) daily for 9 days. Sham-operated rats served as controls. The animals were anesthetized on day 13, and catheters were placed into the femoral artery and vein. After the animals had recovered from anesthesia, the pressor response to intravenous bolus doses of angiotensin II (50, 100, 200, and 400 ng/kg) were determined after recovery from anesthesia. RESULTS: While the baseline mean arterial blood pressure was not affected by L-NMMA, with or without L-Arg, the pressor response to angiotensin II in the L-NMMA group was significantly increased as compared with that in the control group, at doses of 50, 100, and 200 ng/kg. The response of the L-NMMA plus L-Arg group did not differ significantly from that of the control group. CONCLUSION: Results indicate that the infusion of a nitric oxide synthase inhibitor, at a dose insufficient to produce hypertension, increases the pressor response to angiotensin II.

Angiotensin II↗
PubMed2000

Demonstration and diagnostic significance of pro-gastrin-releasing peptide in medullary thyroid carcinoma.

The expression of pro-gastrin-releasing peptide (proGRP) in medullary thyroid carcinoma (MTC) and other histological types of thyroid carcinoma was studied by an immunohistochemical technique, using polyclonal anti-proGRP antiserum. Immunoreactivity for proGRP was detected exclusively in MTC (n = 7); other histological types (n = 12) were all negative for proGRP. In addition, serum proGRP levels were elevated in patients with primary or recurrent MTC (n = 3), and they changed in parallel with serum calcitonin (CT), and carcinoembryonic antigen (CEA). These results show that proGRP, which is considered to be a specific marker for small-cell lung carcinoma, may be also a potential tumor marker for MTC, in addition to CT and CEA.

Biomarkers, Tumor↗
PubMed2000

Airflow limitation in Japanese smokers: significance of serum neutrophil elastase/alpha(1)-proteinase inhibitor ratio and FEV(1) (%pred) adjusted by pack-years.

BACKGROUND: In spite of the known role of cigarette smoking in the development of airflow limitation (AL), fewer than 20% of smokers actually develop chronic obstructive pulmonary disease (COPD). OBJECTIVES: We examined how smoking histories and indices in blood are related to the degree of AL in asymptomatic smokers in order to determine whether they can predict the development of AL. METHODS: Spirometry and peripheral blood tests were examined in 433 Japanese asymptomatic current smokers at the initial examination. Forced expiratory volume in 1 s (FEV(1)) was measured periodically for 2 or more years (2-13 years) in 66 of the subjects. RESULTS: AL defined as an FEV(1)/vital capacity of less than 0.7, was found in 11.3% (49 of 433) of the smokers. Pack-years of smoking, serum amounts of alpha(1)-proteinase inhibitor, and serum procollagen III peptide activities were correlated with the degree of AL. Fifteen percent (10 of 66) of subjects underwent rapid declines in FEV(1) that were found to be related not with smoking amounts or initial FEV(1), but with low FEV(1) (%pred) adjusted by pack-years and an elevated serum neutrophil elastase/alpha(1)-proteinase inhibitor ratio. These results suggest that smokers with a low FEV(1) out of proportion to pack-years are susceptible smokers at a high risk of developing COPD, and further, that increased proteinase burden relative to antiproteinase activity may contribute to the development of COPD. CONCLUSIONS: We conclude that the serum neutrophil elastase/alpha(1)-proteinase inhibitor ratio and FEV(1) (%pred) adjusted by pack-years can be reliable predictors of the development of COPD.

Adult↗
PubMed2000

Phosphatidylinositol 3-kinase signaling is important for smooth muscle cell replication after arterial injury.

The phosphoinositide 3-kinase [PI(3)K] pathway is a key signaling pathway important for replication of mammalian cells. In this study, we examined the role of PI(3)K in smooth muscle cell (SMC) replication after balloon catheter injury of rat carotid arteries. Protein kinase B (PKB), a downstream target of PI(3)K, was phosphorylated at 30 and 60 minutes after injury and to a lesser degree after 6 hours and 1 and 2 days but not after 7 days. Wortmannin (10 microgram per rat), a PI(3)K inhibitor, given to rats 60 and 5 minutes before and 11 hours after balloon injury, reduced the levels of phosphorylated PKB. SMC replication quantified between 24 to 48 hours was significantly reduced compared with control replication, as were the levels of cyclin D(1). Wortmannin was also administered to rats between days 7 and 8 and between days 7 and 9 after balloon catheter injury. A reduction in levels of phosphorylated PKB was detected, but no decrease in the replication of intimal SMCs was observed in either experiment. These data demonstrate that the PI(3)K signal transduction pathway plays an important role in medial but not intimal SMC replication.

Androstadienes↗
PubMed2000

C19 odd-chain polyunsaturated fatty acids (PUfas) are metabolized to C21-PUfas in a rat liver cell line, and curcumin, gallic acid, and their related compounds inhibit their desaturation.

It was demonstrated that the rat liver cell line BRL-3A converted exogenous C19 odd chain-polyunsaturated fatty acids (PUFAs) into the corresponding C21- and C23-PUFAs as follows: 21:3n-8, 21:4n-8, 23:3n-8, and 23:4n-8 (from 19:3n-8); 21:4n-5, 21:5n-5, 23:4n-5, and 23:5n-5 (from 19:4n-5); 21:5n-2, 21:6n-2, 23:5n-2, and 23:6n-2 (from 19:5n-2). It presumed that these C19 PUFAs were converted through the mimic route to docosahexaenoic acid (22:6n-3) from eicosapentaenoic acid (20:5n-3). In addition, the characterization of the change of fatty acid composition of cellular lipids in rat liver cells were examined, using 19:4n-5 and several fatty acid desaturation inhibitors. Curcumin related compounds, curcumin, capsaicin, isoeugenol, 4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-one, and gallic acid esters with near five carbon numbered alcohol had great changes of fatty acid composition of cellular lipids based on inhibition of the A6 desaturation of C24-PUFAs in rat liver cells.

Alkylation↗
PubMed2000

Automatic control of a robot camera for broadcasting based on cameramen's techniques and subjective evaluation and analysis of reproduced images.

With the goal of achieving an intelligent robot camera system that can take dynamic images automatically through humanlike, natural camera work, we analyzed how images were shot, subjectively evaluated reproduced images, and examined effects of camerawork, using camera control technique as a parameter. It was found that (1) A high evaluation is obtained when human-based data are used for the position adjusting velocity curve of the target; (2) Evaluation scores are relatively high for images taken with feedback-feedforward camera control method for target movement in one direction; (3) Keeping the target within the image area using the control method that imitates human camera handling becomes increasingly difficult when the target changes both direction and velocity and becomes bigger and faster, and (4) The mechanical feedback method can cope with rapid changes in the target's direction and velocity, constantly keeping the target within the image area, though the viewer finds the image rather mechanical as opposed to humanlike.

Algorithms↗
PubMed2000

[In vitro activity of faropenem against beta-lactamase producing clinical isolates].

Each 20 strains of beta-lactamase producing methicillin susceptible Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, and Bacteroides fragilis group were used as the test strains. Drug susceptibility of these strains to faropenem (FRPM), cefdinir, cefditoren, cefcapene, cefteram, cefaclor, and ampicillin was determined by an agar dilution method according to the NCCLS guideline M100-S9. beta-Lactamase activity of the test strains was determined by a spectrophotometric method. In the present study, FRPM was highly active against beta-lactamase-producing strains, and no close correlation was found between the MICs of FRPM for the test strains and their beta-lactamase activities. These results suggest that FRPM has potential in successful application for the treatment of infectious diseases with various types of bacterial pathogens including beta-lactamase producing strains.

Anti-Bacterial Agents↗
PubMed2000

[Antibacterial activities of piperacillin for several resistant strains from respiratory infections--in reference to MRSA, PRSP, BLNAR and P. aeruginosa].

We investigated antibacterial activities of piperacillin (PIPC) for several resistant strains of bacteria isolated from patients with respiratory infections from 1998 to 1999 in comparison with reference drugs and obtained the following results: 1. The majority of methicillin resistant strains of Staphylococcus aureus (MRSA) showed high resistance to beta-lactam antibiotics including PIPC. 2. MIC90 of PIPC was 1 and 4 micrograms/ml for penicillin intermediate and penicillin resistant strains of Streptococcus pneumoniae (PISP/PRSP), respectively. 3. MIC90 of PIPC was 0.25 microgram/ml for beta-lactamase negative ampicillin resistant strains of Haemophilus influenzae (BLNAR), showing higher antibacterial activity than the reference drugs. 4. PIPC exhibited the MICs of 8 micrograms/ml or less in 19 out of 40 IPM resistant (MIC > or = 16 micrograms/ml) strains of Pseudomonas aeruginosa. From these results, PIPC is proved to possess extremely favorable antibacterial activities for BLNAR, and it was suggested that PIPC might be a drug of choice even for PISP/PRSP and IPM resistant strains of P. aeruginosa.

Ampicillin↗
PubMed2000

[Antibacterial activities of piperacillin in several fresh clinical isolates].

We investigated activity of piperacillin (PIPC) in comparison with 8 antibacterial reference drugs against several fresh clinical strains isolated from patients with infectious diseases in the respiratory tract and after surgical interventions in 1999. The following results were obtained: 1. PIPC had its MIC90 of 0.12-6 micrograms/ml in Gram-positive bacteria (Methicillin susceptible Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, Enterococcus faecalis) and showed its MIC of 1 microgram/ml or higher in 9 possible PRSP strains out of 38 isolates of S. pneumoniae but there were no possible isolates with evident resistance in other species of bacteria. 2. PIPC showed favorable antibacterial activities as its MIC90 were 2-8 micrograms/ml in Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, Pseudomonas aeruginosa, Moraxella (Branhamella) catarrhalis, Haemophilus influenzae), except for P. mirabilis in which its MIC90 was as high as 64 micrograms/ml. 11 out of 39 isolates of P. mirabilis were resistant to other drugs such as PIPC, ABPC, CTM and CZOP. 3. PIPC had its MIC90 of > 128 micrograms/ml in Bacteroides fragilis. From these results, PIPC was considered highly effective in several infections in view of maintaining its favorable antibacterial activities in several causative bacteria even today when 20 years had passed since its first application to clinical practice.

Bacteroides fragilis↗