496 research outputs found

    A Study of Micronucleus Induction with Methyl Formate and 2-Methylbutane in Bone Marrow Cells of Male ICR Mice

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    Objectives: We investigated the genotoxicity of two chemicals, methyl formate and 2-methylbutane, using male ICR mice bone marrow cells for the screening of micronucleus induction. Although these two chemicals have already been tested numerous times, a micronucleus test has not been conducted and the amounts used have recently been increased.Methods: 7 week male ICR mice were tested at dosages of 250, 500, and 1,000mg/kg for methyl formate and 500, 1,000, and 2,000mg/kg for 2-methlybutane, respectively. After 24 hours of oral administration with the two chemicals, the mice were sacrificed and their bone marrow cells were prepared for smearing slides.Results: As a result of counting the micronucleated polychromatic erythrocyte (MNPCE) of 2,000 polychromatic erythrocytes (PCE), all treated groups expressed no statistically significant increase of MNPCE compared to the negative control group. There were no clinical signs related with the oral exposure of these two chemicals.Conclusion: It was concluded that the two chemicals did not induce micronucleus in the bone marrow cells of ICR mice, and there was no direct proportion with dosage. These results indicate that the two chemicals have no mutagenic potential under each study condition

    Pneumocephalus in Patients With Orthostatic Headache

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    Cerebrospinal fluid (CSF) leak or shunt overdrainage is a well-known cause of orthostatic headaches and low CSF pressures. We report two cases of orthostatic headache with pneumocephalus on brain imaging. The orthostatic headache developed after drainage of spinal operation site and epidural block. Brain MRI revealed characteristic findings of CSF hypovolemia including pachymeningeal enhancement and mild subdural fluid collections. Air was also observed in the ventricular or subarachnoid space in both patients, which might enter the subarachnoid or ventricular space during a procedure via the pressure gradient or an injection

    Two levels above and one level below pedicle screw fixation for the treatment of unstable thoracolumbar fracture with partial or intact neurology

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    <p>Abstract</p> <p>Background</p> <p>Treatment of unstable thoracolumbar fractures is controversial regarding short or long segment pedicle screw fixation. Although long level fixation is better, it can decrease one motion segment distally, thus increasing load to lower discs.</p> <p>Methods</p> <p>We retrospectively analyzed 31 unstable thoracolumbar fractures with partial or intact neurology. All patients were operated with posterior approach using pedicle screws fixed two levels above and one level below the fracture vertebra. No laminectomy, discectomy or decompression procedure was done. Posterior fusion was achieved in all. Post operative and at final follow-up radiological evaluation was done by measuring the correction and maintenance of kyphotic angle at thoracolumbar junction. Complications were also reported including implant failure.</p> <p>Results</p> <p>Average follow-up was 34 months. All patients had full recovery at final follow-up. Average kyphosis was improved from 26.7° to 4.1° postoperatively and to 6.3° at final follow-up. And mean pain scale was improved from 7.5 to 3.9 postoperatively and to 1.6 at final follow-up, All patients resumed their activity within six months. Only 4 (12%) complications were noted including only one hardware failure.</p> <p>Conclusion</p> <p>Two levels above and one level below pedicle screw fixation in unstable thoracolumbar burst fracture is useful to prevent progressive kyphosis and preserves one motion segment distally.</p

    Fifteen Years After the Gozan-Dong Glass Fiber Outbreak, Incheon in 1995

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    Objectives: In 1995, an outbreak survey in Gozan-dong concluded that an association between fiberglass exposure in drinking water and cancer outbreak cannot be established. This study follows the subjects from a study in 1995 using a data linkage method to examine whether an association existed. The authors will address the potential benefits and methodological issues following outbreak surveys using data linkage, particularly when informed consent is absent. Methods: This is a follow-up study of 697 (30 exposed) individuals out of the original 888 (31 exposed) participants (78.5%) from 1995 to 2007 assessing the cancer outcomes and deaths of these individuals. The National Cancer Registry (KNCR) and death certificate data were linked using the ID numbers of the participants. The standardized incidence ratio (SIR) and standardized mortality ratio (SMR) from cancers were calculated by the KNCR. Results: The SIR values for all cancer or gastrointestinal cancer (GI) occurrences were the lowest in the exposed group (SIR, 0.73; 95% CI, 0.10 to 5.21; 0.00 for GI), while the two control groups (control 1: external, control 2: internal) showed slight increases in their SIR values (SIR, 1.18 and 1.27 for all cancers; 1.62 and 1.46 for GI). All lacked statistical significance. All-cause mortality levels for the three groups showed the same pattern (SMR 0.37, 1.29, and 1.11). Conclusions: This study did not refute a finding of non-association with a 13-year follow-up. Considering that many outbreak surveys are associated with a small sample size and a cross-sectional design, follow-up studies that utilize data linkage should become standard procedure.OAIID:oai:osos.snu.ac.kr:snu2011-01/102/0000040632/15SEQ:15PERF_CD:SNU2011-01EVAL_ITEM_CD:102USER_ID:0000040632ADJUST_YN:YEMP_ID:A077602DEPT_CD:902CITE_RATE:0FILENAME:fifteen years after the gozan-dong glass fiber outbreak, incheon in 1995..pdfDEPT_NM:보건학과CONFIRM:

    In vitro and in vivo Inhibitory Activity of NADPH Against the AmpC BER Class C β-Lactamase

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    β-Lactamase-mediated resistance to β-lactam antibiotics has been significantly threatening the efficacy of these clinically important antibacterial drugs. Although some β-lactamase inhibitors are prescribed in combination with β-lactam antibiotics to overcome this resistance, the emergence of enzymes resistant to current inhibitors necessitates the development of novel β-lactamase inhibitors. In this study, we evaluated the inhibitory effect of dinucleotides on an extended-spectrum class C β-lactamase, AmpC BER. Of the dinucleotides tested, NADPH, a cellular metabolite, decreased the nitrocefin-hydrolyzing activity of the enzyme with a Ki value of 103 μM in a non-covalent competitive manner. In addition, the dissociation constant (KD) between AmpC BER and NADPH was measured to be 40 μM. According to our in vitro susceptibility study based on growth curves, NADPH restored the antibacterial activity of ceftazidime against a ceftazidime-resistant Escherichia coli BER strain producing AmpC BER. Remarkably, a single dose of combinatory treatment with NADPH and ceftazidime conferred marked therapeutic efficacy (100% survival rate) in a mouse model infected by the E. coli BER strain although NADPH or ceftazidime alone failed to prevent the lethal bacterial infection. These results may offer the potential of the dinucleotide scaffold for the development of novel β-lactamase inhibitors
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