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Masato Maekawa

Publications and source records attributed to Masato Maekawa.

50 records · Page 3Linked to original sources
PubMed2003

Characterization of Pseudomonas aeruginosa isolates from patients with urinary tract infections during antibiotic therapy.

We characterized susceptibilities and genotypes in a series of Pseudomonas aeruginosa isolates from five cases of urinary tract infections (UTIs) to evaluate clonal shifts of carbapenem resistance. In one case, a series of isolates showed different susceptibility patterns for carbapenems but an identical genotype. In another case, genotypes varied among 4 P. aeruginosa isolates from recurrent UTIs over 9 months. Although the patient had been treated with no antibiotic immediately before isolation, the susceptibility patterns for carbapenems and ceftazidime varied. Further analysis in these two cases of outer membrane protein profiles showed that loss of OprD production resulted in reduced susceptibilities to carbapenems in all of the carbapenem-resistant isolates. Loss of OprD production was likely due to oprD gene inactivation in both of cases, since the carbapenem-resistant isolates showed no cross resistance to levofloxacin and chloramphenicol compared with the carbapenem-susceptible isolates. There was another case in which all isolates showed similar susceptibility patterns for carbapenems and ceftazidime, and an identical genotype during the intermittent use of antibiotics over 5 months. In two cases, a single course of antibiotic therapy resulted in eradication of P. aeruginosa. Our results suggest that clonal shifts of carbapenem resistance in P. aeruginosa may result from loss of OprD during antibiotic treatment. Therefore, it is important for clinicians to monitor susceptibilities to antibiotics, especially carbapenems, in P. aeruginosa isolated during therapy.

Adult↗
PubMed2003

Detection of macrolide resistance in Streptococcus pneumoniae.

We determined the susceptibilities of recent clinical isolates of Streptococcus pneumoniae to 19 antibiotics. The frequency of erythromycin nonsusceptibility was high, i.e. 8/13 (61.5%), 10/14 (71.4%) and 11/11 isolates (100%) from 13 penicillin-susceptible, 14 penicillin-intermediate and 11 penicillin-resistant S. pneumoniae, respectively. Macrolide resistance was detected by polymerase chain reaction (PCR) and disk diffusion methods. Of these erythromycin-nonsusceptible pneumococcal isolates, 13/29 (44.8%) isolates contained genomic copies of MEFA and showed non-'D'-shaped zones of inhibition observed around rokitamycin and/or clindamycin disks. Sixteen out of 29 isolates (55.2%) contained copies of ERMB and showed typical 'D'-shaped zones of inhibition, except one isolate. Although the macrolide resistance determinants, MEFA and ERMB, could be identified by PCR and disk diffusion methods, PCR methods were more reliable in elucidating these determinants. The susceptibility pattern to 14-, 15- and 16-membered macrolides and clindamycin differed between the MEFA+ and ERMB+ isolates. All isolates were susceptible to levofloxacin, sparfloxacin and vancomycin. The MICs of sitafloxacin were lowest among the fluoroquinolones examined for 38 isolates.

Anti-Bacterial Agents↗
PubMed2003

A common truncated variant of lipoprotein lipase in the Japanese population is characterized by pattern B phenotype.

To investigate the relationship between the lipoprotein lipase Ser447Ter (S447X) mutation, lipid profiles and risk of atherosclerotic disease, we studied two groups of Japanese subjects. These groups consisted of a dyslipidemic group (triglyceride (TG) > 1.69 mmol/l and high-density lipoprotein-cholesterol (HDL-C) < or = 0.91 mmol/l; n = 106) and a control group (TG < or = 1.69 mmol/l and HDL-C > or = 1.16 mmol/l; n = 106). All subjects in the control group were confirmed to the pattern A phenotype (normal low-density lipoprotein (LDL) pattern), and 21 individuals in this group were heterozygous for the S447X mutation, but not homozygous. In the patient group, pattern A was shown by 44 of 106 patients. The rest were of the pattern B phenotype, which is associated with an increased risk of coronary heart disease. Homozygosity was concentrated in the patient group (p < 0.05) and in those with the pattern B phenotype (p < 0.05). In contrast, heterozygosity between both groups was not statistically significant. In conclusion, heterozygous and homozygous status with respect to the LPL S447X mutation appears to have different meanings with respect to biochemical and clinical phenotypes of atherosclerosis.

Adolescent↗
PubMed2003

Relationship between high-density lipoprotein-cholesterol and malondialdehyde-modified low-density lipoprotein concentrations.

Several reports have suggested that HDL has anti-oxidative actions. We investigated the relationship between HDL-cholesterol (HDL-C) and malondialdehyde-modified LDL (MDA-LDL) concentrations using enzyme linked immunosolvent assay. We divided our study subjects into four groups on the basis of concentrations of triglyceride (TG) and HDL-C by the following lipid profiles: serum TG < or = 1.69 mmol/L and HDL-C > or = 1.16 mmol/L (control group, n = 26); TG >1.69 and HDL-C < or = 1.16 (high TG group, n = 22); TG >1.69 and HDL-C < or = 0.91 (high TG & low HDL group, n = 67); TG < or = 1.69 and HDL-C < or = 0.91 (low HDL group, n = 21). MDA-LDL concentrations, MDA-LDL/apolipoprotein B (apo B) ratio, and LDL size were different between subjects in high TG & low HDL and control groups. MDA-LDL concentrations in both high TG and low HDL groups did not differ significantly from those in the control. However, MDA-LDL/apo B ratio in low HDL group was significantly higher than that in the control (P < 0.05). The MDA-LDL/apo B ratio reflects the extent of MDA modification of apo B in LDL. Therefore, our data suggest that as HDL-C concentrations fall, the extent of MDA modification per one LDL particle increases. Moreover, accompanied by high TG concentration, LDL size in subjects with lower HDL-C concentrations became smaller.

Adult↗
PubMed2003

[Basic studies on mutation analysis of K-ras codon 12 by use of three-dimensional microarray system].

A next-generation DNA microarray system, FD10 has been developed. It is based around the PamChip, a custom-made microarray, which consists of a solid three-dimensional structure that facilitated the incorporation of probe molecules. We applied this microarray system on a detection of K-ras mutation at codon 12 in some cancer cell lines. The PCR products amplified by use of FITC labeled primers were applied onto probe-absorbed microarray. After hybridization, the signal was imaged by CCD camera and analyzed by the exclusive software. We confirmed the microarray results by PCR-SSCP and sequencing analyses. Ten, two and three out of 15 cell lines were homozygous for wild type allele, heterozygous for wild and mutant allele, and homozygous for mutant alleles, respectively. Signals hybridized with antisense probes were stronger than those with sense probes, without PSN1 cell line. The system had a good reproducibility. Essentially, the microarray results were consistent with PCR-SSCP and sequencing results. In conclusion, the FD10 microarray system was easy to operate and short to get results. It might be useful for a focused array applicable for specific purposes. The K-ras mutation detection system worked well and will be applied to clinical specimens soon.

Codon↗
PubMed2002

Role of Wnt pathway in medulloblastoma oncogenesis.

To clarify the roles of Wnt pathway in medulloblastoma oncogenesis, immunohistochemical staining of beta-catenin and Wnt-1 and genomic analyses of CTNNB1 (beta-catenin) and AXIN1 (axin 1) were examined in 23 sporadic cases. Accumulation of beta-catenin in tumor cells was immunohistochemically proven in 5 cases; 2 cases showed positive immunoreactivity for Wnt-1 and another 2 showed mutation of either CTNNB1 or AXIN1. AXIN1 mutation was in exon 3, corresponding to GSK-3beta binding site and CTNNB1 mutation was in exon 3, corresponding to its phosphorylation site. Disruption of these proteins could result in upregulation of the Wnt signaling and accumulation of beta-catenin, followed by cell proliferation and medulloblastoma oncogenesis.

Axin Protein↗
PubMed2002

Antibacterial activities of beta-lactamase inhibitors associated with morphological changes of cell wall in Helicobacter pylori.

BACKGROUND: Recent study has demonstrated that beta-lactamase inhibitors including clavulanate, sulbactam and tazobactam have an vitro antibacterial effect on Helicobacter pylori. Here we describe the relationship between viability and cell profiles of H. pylori exposed to beta-lactamase inhibitors and some antibiotics in a short-time course. MATERIALS AND METHODS: The antibacterial effects of beta-lactamase inhibitors including clavulanate, sulbactam and tazobactam on the bacterial viability of and morphological changes in H. pylori ATCC43504 were examined. RESULTS: The beta-lactamase inhibitors such as clavulanate and sulbactam alone decreased the viable counts of H. pylori, depending on the antibiotic concentrations. Exposure to these beta-lactamase inhibitors resulted in morphological changes of cell shape, cell-wall disintegration and cell lysis. Among these beta-lactamase inhibitors, clavulanate was the most active, causing a decrease in viable counts and morphological changes such as short filamentous to sphaeroplast formation and lysis. One x minimum inhibitory concentration (MIC) of amoxicillin plus 1 x MIC of clavulanate decreased viable counts effectively compared with 1 x MIC of amoxicillin or 1 x MIC of clavulanate alone, and induced morphological changes of cell shape and cell wall. CONCLUSION: Our results suggest that the beta-lactamase inhibitors alone have concentration-dependent antibacterial activities against H. pylori and affect the morphology of the cell shape and the cell wall in vitro.

Anti-Bacterial Agents↗
PubMed2002

Methylation status and expression of human telomerase reverse transcriptase mRNA in relation to hypermethylation of the p16 gene in colorectal cancers as analyzed by bisulfite PCR-SSCP.

BACKGROUND: The expression level of human telomerase reverse transcriptase (hTERT) is correlated with telomerase activity and is expressed at high levels in malignant tumors. It is of interest whether expression of hTERT is regulated by methylation of the CpG island in the promoter of the hTERT gene. We examined hTERT expression and methylation status of the hTERT and other genes including p16. METHODS: We analyzed methylation status by bisulfite treatment and polymerase chain reaction with single-strand conformation polymorphism analysis (PCR-SSCP) and expression of the hTERT by RT-PCR, in 13 cancer cell lines, eight white blood cell samples and 24 colorectal cancer tissues. RESULTS: In the cancer cell lines, hTERT was expressed and the CpG island of the hTERT promoter was methylated. Most colorectal cancer tissues showed similar results. The promoter of hTERT was methylated in six cases, partially methylated in 17 cases and unmethylated in one case. All cases with methylation of hMLH1 or p16 also showed methylation of hTERT; however, some of the cases lacking p16 methylation also had hTERT methylation. CONCLUSION: Increased expression of hTERT is related to hypermethylation of hTERT in colorectal cancerous tissues as well as some cancer cell lines and disconcordant with hypermethylation of p16.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Insulin treatment prevents LDL from accelerated oxidation in patients with diabetes.

In a study population, we compared the level of malondialdehyde-modified LDL (MDA-LDL) with the concentrations of lipid parameters in serum and found a strong correlation between MDA-LDL and apolipoprotein B (apo B) concentrations. Their interrelations had a turning point at an apo B concentration of 1,150 mg/l. In diabetic patients, the ratio of MDA-LDL/apo B increased at apo B concentrations above 1,150 mg/l. This ratio represents the extent of modification of apo B by MDA. In the control subjects, this ratio remained stable. When we divided the patients into medication groups (statins and insulin), we found that the 1,150 mg/l threshold disappeared. At apo B concentrations above 1,150 mg/l, the ratio of MDA-LDL/apo B in the statin group was as high as that in the non-drug group. In the insulin group, the means of MDA-LDL/apo B in all ranges of apo B levels decreased to an extent statistically indistinguishable from those of the control group. In conclusion, insulin therapy represses LDL oxidation even at apo B concentrations > 1,150 mg/l and should be noted for its anti-oxidation properties.

Adult↗
PubMed2002

Electrophoretic variant of a lactate dehydrogenase isoenzyme and selective promoter methylation of the LDHA gene in a human retinoblastoma cell line.

BACKGROUND: Lactate dehydrogenase (LD), a tetrameric product of the genes LDHA and LDHB, may be increased in sera of cancer patients. A variant isoenzyme with electrophoretic mobility between LD2 and LD3 (LD2ex) has been described in patients, but its molecular nature is largely unknown. METHODS: A newly established retinoblastoma cell line, NCC-RbC-51 (R51), showed an isoenzyme pattern with only two bands, LD1 and LD2ex. We investigated the isoenzymes by Northern blot, Western blot, and methylation analysis and PCR. RESULTS: Northern blot analysis revealed that R51 cells expressed no wild-type/somatic LDHA mRNA, but did express a small amount of LDHA-related mRNA with a slightly higher molecular mass. Western blot analysis confirmed the anti-LDHA-reactive protein with a 3-kDa higher molecular mass. Treatment of R51 cells with the demethylating agent 5-aza-2'-deoxycytidine restored the expression of the LD2, -3, -4, and -5 isoenzymes. PCR analysis of sodium bisulfite-treated genomic DNA revealed that the CpG island in the promoter region around exon a of the LDHA gene was completely methylated. Reverse transcription-PCR analysis and direct sequencing revealed that R51 cells expressed a RNA with the sequence of the human homolog of a murine testis-specific variant that has exon 0 as the 5' noncoding sequence. LDHB was expressed normally in R51 cells. CONCLUSIONS: The somatic LDHA in R51 cells is transcriptionally silenced by promoter hypermethylation around exon a, leaving only LDHB to be expressed normally and a testis-specific variant transcript of LDHA containing exon 0. LD2ex possibly results from tetramerization of three wild-type LDHB molecules and one variant LDHA product.

Blotting, Northern↗
PubMed2002

[Familial (hereditary) cancer].

When cancer patients accumulated in one pedigree, the cancer is named as familial cancer. Especially when there is strong genetic background, It is named as hereditary cancer. Most of them are caused by genetic mutation in a gene related to cancer susceptibility. The gene is classified among suppressor oncogenes, oncogenes or DNA repair genes. Although hereditary cancer is uncommon, genetic testing is very useful to confirm hereditary cancer and to diagnose it in the presymptomatic stage. On the other hand, it poses ethical problems, therefore a strategy including genetic counseling is essential.

DNA Repair↗