• Biomedical Science Letters
• /
• v.5 no.1
• /
• pp.27-40
• /
• 1999

This study was focused on the evaluation of MarB alongside with MarA for its regulatory effects upon the efflux function of AcrAB pump, which were induced or not, perhaps as a target. Transductions of marR and/or acrAB mutation which were derived from Mar and/or AcrAB mutants of wild type E. coli K-12, respectively, into the multicopy plasmid in wild type E. coli backgrounds or into the chromosome of isogenic parents were done. Minimal inhibitory concentration (MIC) of transduced mutants was compared with their original mutants. This study reports the indirect evidences that suggests a model in which MarB along with MarA have a putative negative regulatory effect upon the efflux function of AcrAB/TolC pump while MarA alone have a positive regulatory effect to the expression of acrRAB operon at transcription level. The target of MarB with MarA for its putative negative regulator might be the AcrAB efflux pump. Another efflux system (s) might be negatively regulated by MarB with MarA, and be involved in the efflux of antibiotics which were otherwise extruded preferentially by AcrAB efflux pump.

• Journal of radiological science and technology
• /
• v.41 no.5
• /
• pp.413-419
• /
• 2018

Magnetic Resonance Imaging for patients with metallic implant has poor image quality, and signal loss and artifacts including distortion can occur. The purpose of this study is to carry out a comparative evaluation on high receive bandwidth(hiBW), O-MAR, O-MAR XD to reduce artifacts in knee implant. To take MRI, 3.0T scanner and dual-source radiofrequency transmission were used. O-MAR XD technique's strong option showed a significant difference (p<0.001) with O-MAR XD technique's weak option, O-MAR and hiBW excluding the medium option. O-MAR XD's medium option had a significant difference (p<0.01) with O-MAR XD's weak, O-MAR and hiBW. O-MAR XD technique's weak option had a significant difference (p<0.01) with O-MAR XD's strong and medium options, O-MAR and hiBW. O-MAR technique had a significant difference (p<0.001) with strong, medium, weak options of O-MAR XD technique except for hiBW. HiBW had a significant difference (p<0.001) with strong, medium and weak options of O-MAR XD technique except for O-MAR. The results showed that O-MAR XD technique was more useful for MRI scan for patients with knee replacement surgery than traditional techniques such as hiBW or O-MAR, and susceptibility artifacts decreased more when O-MAR XD technique's strong or medium option was applied. Based on the results above, it is considered that it will be possible to acquire images whose susceptibility artifacts were highly decreased by using O-MAR XD technique's strong or medium option when conducting MRI for artificial knee joint and it will be helpful for checking and monitoring patients with knee joint replacement.

• Biomedical Science Letters
• /
• v.10 no.2
• /
• pp.153-161
• /
• 2004

Antibiotic resistance is often associated with the production of inner membrane proteins (for example, AcrAB/TolC efflux pump) that are capable to extrude antibiotics, detergents, dyes and organic solvents. In order to evaluate the unknown MarB function of Escherichia coli, especially focused on the function of OmpF porin, several mutants were construted by T4GT7 transduction. MarA plays a major roles in mar (multiple antibiotic resistance) phenotype with AcrAB/TolC efflux pump in E. coli K-12. Futhermore, MarA decreases OmpF porin expression via micF antisense RNA. Expression of acrAB is increased in strains containing mutation in marR, and in those carrying multicopy plasmid expressing marA. MarB protein of E. coli K-12 showed its activity at OmpF porin & TolC protein as target molecule. Some paper reported MarB positively regulates OmpF function. MarA shows mar phenotype, and MarB along with MarA show decreased MIC through OmpF function. By this experiment, MarB could decrease MIC through the OmpF porin & TolC protein as target.

• Biomedical Science Letters
• /
• v.5 no.1
• /
• pp.17-26
• /
• 1999

To evaluate the spreading possibilities of the marRAB mutation of E. coli Mar mutant among gram-negative bacilli, chromosomal marRAB mutations of Mar mutants were transduced by $\lambda$placMu9 into pUC19 (Lac$^{+}$, Ap$^{r}$) cloning site in another strains of E. coli or onto the chrmosome of S. typhimurium and P. aeruginosa, selected for transduction by Mar phenotype, Lac$^{-}$, or Ap$^{r}$, and tested for their antimicrobial resistance with or without addition of salicylate (SAL). Compared with wild type strains of JM109, NM522, harboring pUC19 or not, respectively, all strains of JM109 or NM522 carrying pUC19::marRAB mutation showed higher levels of antimicrobial resistance and SAL induction of Mar phenotype than those of wild type. However, in contrast to the original Mar mutants, there were some tendencies of decreased antimicrobial resistance of JM109 or NM522 harboring pUC19::marRAB mutation with SAL induction against chlorarnphenicol (Cm) and tetracycline (Tc), or Tc and ciprofloxacin (Cp), respectively. Almost the same results, as shown as the cases of E. coli JM109 or NM522, were obtained from all transductants of S. typhimurium and P. aeruginosa, except Cp, against which increased antimicrobial resistance with SAL induction was shown. This study, employed the methods of transformation or transduction among intercellular gene transfer methods between gram-negative bacteria, shows the evidences that suggest indirectly the spreading possibilities of marRAB mutation among gram-negative bacilli.

• The Journal of Korean Society for Radiation Therapy
• /
• v.29 no.2
• /
• pp.9-17
• /
• 2017

Purpose: The tissue description and electron density indicated by the Computed Tomography(CT) number (also known as Hounsfield Unit) in radiotherapy are important in ensuring the accuracy of CT-based computerized radiotherapy planning. The internal metal implants, however, not only reduce the accuracy of CT number but also introduce uncertainty into tissue description, leading to development of many clinical algorithms for reducing metal artifacts. The purpose of this study was, therefore, to investigate the accuracy and the clinical applicability by analyzing date from SMART MAR (GE) used in our institution. Methode: and material: For assessment of images, the original images were obtained after forming ROIs with identical volumes by using CIRS ED phantom and inserting rods of six tissues and then non-SMART MAR and SMART MAR images were obtained and compared in terms of CT number and SD value. For determination of the difference in dose by the changes in CT number due to metal artifacts, the original images were obtained by forming PTV at two sites of CIRS ED phantom CT images with Computerized Treatment Planning (CTP system), the identical treatment plans were established for non-SMART MAR and SMART MAR images by obtaining unilateral and bilateral titanium insertion images, and mean doses, Homogeneity Index(HI), and Conformity Index(CI) for both PTVs were compared. The absorbed doses at both sites were measured by calculating the dose conversion constant (cCy/nC) from ylinder acrylic phantom, 0.125cc ionchamber, and electrometer and obtaining non-SMART MAR and SMART MAR images from images resulting from insertions of unilateral and bilateral titanium rods, and compared with point doses from CTP. Result: The results of image assessment showed that the CT number of SMART MAR images compared to those of non-SMART MAR images were more close to those of original images, and the SD decreased more in SMART compared to non-SMART ones. The results of dose determinations showed that the mean doses, HI and CI of non-SMART MAR images compared to those of SMART MAR images were more close to those of original images, however the differences did not reach statistical significance. The results of absorbed dose measurement showed that the difference between actual absorbed dose and point dose on CTP in absorbed dose were 2.69 and 3.63 % in non-SMRT MAR images, however decreased to 0.56 and 0.68 %, respectively in SMART MAR images. Conclusion: The application of SMART MAR in CT images from patients with metal implants improved quality of images, being demonstrated by improvement in accuracy of CT number and decrease in SD, therefore it is considered that this method is useful in dose calculation and forming contour between tumor and normal tissues.

• Korean Journal of Community Nutrition
• /
• v.4 no.1
• /
• pp.46-56
• /
• 1999

A deep understanding of the dietary patterns and nutrient intake is important for assessment of possilbe nutritional risk and for establishing nutrition improvement strategies. This study was conducted toexamine the dietary characteristics of a nutritionally poor elderly group compared to the middle-and highly-nourished group. Elderly participant was recruited from local elderly centers in Suwon city in 1998. Trained dietitians interviewed 119 elderly(35 males, 84 females) aged 60 years and over for collecting dietary data(24-hour recall) and related variables. Male and female subjects were grouped into high, middle, and low according to the mean nutrient adequancy ratio(MAR) tertiles. An analysisof the percentage of RDA(Recommended Daily Allowances of Korea) for each of the 10 nutrients showed that the male low-MAR group consumed below the RDA in all kinds of nutrients, and the female low-MAR group consumed nutrients below the RDA except vitamin C. An evaluation of nutrient density by Index of Nutritonal Quality(INQ) also showed a similar tendency. Thus, the INQ level of the male low-MAR group was significantly lower than the middle-or high-MAR group, especially in protein, vitamin A, thiamin, riboflavin, and phosphorus(p<0.05). Moreover, INQ level of female low-MAR group was significantly lower than that of the high group(p<0.05) in all nutrients. The female low-MAR group's daily food intake were also lower than those of the high-MARgroup in gains, fish, fruits, oil and beverages. The energy distribution from carbohydrates, fats and proteins showed that the male low-MAR group had significantly higher carbohydrate and lower fat proportions compared to each gender high-MAR group, respectively. The male and female low-MAR group had low scores about eating all side dishes. These findings indicate that a moderate increase of the meat/egg/fishes intake was needed by the male low-MAR group for improving nutrition adequacy, and an overall increase of the food quantity and quality was desired for the female low-MAR group. These data could be used for planning a community elderly nutrition program and establishing strategies for tailored guidelines for the individuals.

• Proceedings of the KSAR Conference
• /
• 2003.06a
• /
• pp.40-40
• /
• 2003

형질전환체 제작 시 발현벡터가 삽입되는 위치에 따라 발현 또는 억제되는 현상인 ‘position effect(위치효과)’를 극복하기 위해 Matrix Attachment Region(MAR)을 포함하는 발현벡터를 제작하였다 MAR는 핵 기질(nuclear matrix) 부착 부위로 발현조절에 관여하는 전사인자 등이 존재하는 핵 기질 부착부위로, 삽입된 발현벡터가 전사활성을 할 수 있는 게놈 환경을 제공해 주어 형질전환 유전자 발현을 향상시켜 준다고 보고되고 있다. 본 연구에서는 사람에서 이미 분리되어 염기서열이 밝혀진 MAR를 PCR로 증폭하였다. 증폭된 1,270 bp의 human alpha-1-antitrypsin MAR와 1,080 bp human corticosteroid binding globulin promoter MAR를 T vector에 클로닝하여 염기서열을 확인했으며 발현벡터 클로닝에 사용하였다. 유용 유전자와 세포 형질전환에 사용할 선별 유전자로 neo를 포함하며, 그 외 벡터골격은 pGL3 control vector를 사용하여 기본 발현벡터를 제작하였다. 이 벡터에 MAR를 5', 3' 양쪽 또는 한쪽만 포함하도록 클로닝하였다. 이는 MAR의 위치에 따른 게놈내 삽입 및 발현효과를 확인하여 형질전환동물 생산용 발현벡터로 활용하고자 한다.

• Journal of the Korean Society of Radiology
• /
• v.16 no.2
• /
• pp.131-139
• /
• 2022

The purpose of this study was to insert a pedicle screw into a pig thoracic vertebrae, a general CT scan(Non MAR), and a thoracic axial image obtained with the Metallic Artifact Reduction for Orthopedic Implants (O-MAR) to reduce artifacts. The image obtained by reconstructing the algorithm (Standard, Soft, Bone, Detail) was used using the image J program. Signal to noise ratio(SNR) and contrast to noise ratio(CNR) were compared and analyzed by obtaining measured values based on the given equation. And this study was to investigate tube voltage and algorithm suitable for CT scan for thoracic pedicle screw insertion. As a result, when non-MAR was used, the soft algorithm showed the highest SNR and CNR at 80, 100, 120, and 140 kVp, On the other hand, when MAR was used, the standard algorithm showed the highest at 80 kVp, and the standard and soft algorithms showed similar values at 100 kVp. At 120 kVp, the Soft and Standard algorithms showed similar values, and at 140 kVp, the Soft algorithm showed the highest SNR and CNR. Therefore, when comparing Non-MAR and MAR, even if MAR was used, SNR and CNR did not increase in all algorithms according to the change in tube voltage. In conclusion, it is judged that it is advantageous to use the Soft algorithm at 80, 100, 120, and 140 kVp in Non MAR, the Standard algorithm at 80 and 100 kVp in MAR, and the Soft algorithm at 120 and 140 kVp. This study is expected to serve as an opportunity to further improve the quality of images by using selective tube voltage and algorithms as basic data to help evaluate images of pedicle screw CT scans in the future.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.16 no.2
• /
• pp.35-43
• /
• 2012

Purpose : PET/CT performed CT-based attenuation correction generates the beam hardening artifact by metallic implant. The attenuation correction causes over or underestimate of the area adjacent to metallic hip prosthetic material and change of $^{18}F$-FDG uptake. Also, the image quality and the diagnosability on genitourinary disease are reduced. Therefore, this study will evaluate the usefulness of MAR (Metal Artifact Reduction) algorithm method to improve the image quality on PET/CT. Materials and Methods : PET/CT was performed by fixing hip prosthesis in SPECT/PET phantom. In PET images with and Without MAR algorithm, the Bright streak, Dark streak, Metal region and Background area that appeared on CT were confirmed, and the change of each SUV (standardized uptake value) was analyzed. Also, in 15 patients who underwent total hip arthroplasty, each MAR algorithm and Without MAR algorithm and non attenuation correction was evaluated. Results : In PET image Without MAR algorithm, SUV of Bright streak region was $0.98{\pm}0.48$ g/ml; Dark streak region was $0.88{\pm}0.02$ g/ml; Metal region was $0.24{\pm}0.16$ g/ml, Background area was $0.91{\pm}0.18$ g/ml. In SUV of PET image with MAR algorithm, Bright streak region was $0.88{\pm}0.49$ g/ml, Dark streak region was $0.63{\pm}0.21$ g/ml, Metal region was $0.06{\pm}0.07$ g/ml, Background was $0.90{\pm}0.02$ g/ml. SUV generally decreased when applying MAR algorithm. In PET image Without MAR algorithm, SUVs of Bright region were higher than those measured in the Background, and it was false positive uptake. But, in PET image with MAR algorithm, SUVs of Bright region were similar to the Background, and false positive uptake disappeared. Conclusion : MAR algorithm could reduce an increase of $^{18}F$-FDG uptake due to attenuation correction in the hip surrounding tissue. However, decrease of SUV in Dark streak region should be considered in the future. Therefore, this study propose that the diagnostic accuracy can be improved in genitourinary diseases adjacent to metallic hip prosthesis, if provided PET images with and Without MAR algorithm, and non attenuation correction images at the same time.

• The Journal of Korean Society for Radiation Therapy
• /
• v.26 no.1
• /
• pp.107-114
• /
• 2014

Purpose : The purpose of this study is evaluation for the applicability of O-MAR(Metal artifact Reduction for Orthopedic Implants)(ver. 3.6.0, Philips, Netherlands) in head & neck radiation treatment planning CT with metal artifact created by dental implant. Materials and Methods : All of the in this study's CT images were scanned by Brilliance Big Bore CT(Philips, Netherlands) at 120kVp, 2mm sliced and Metal artifact reduced by O-MAR. To compare the original and reconstructed CT images worked on RTPS(Eclipse ver 10.0.42, Varian, USA). In order to test the basic performance of the O-MAR, The phantom was made to create metal artifact by dental implant and other phantoms used for without artifact images. To measure a difference of HU in with artifact images and without artifact images, homogeneous phantom and inhomogeneous phantoms were used with cerrobend rods. Each of images were compared a difference of HU in ROIs. And also, 1 case of patient's original CT image applied O-MAR and density corrected CT were evaluated for dose distributions with SNC Patient(Sun Nuclear Co., USA). Results : In cases of head&neck phantom, the difference of dose distibution is appeared 99.8% gamma passing rate(criteria 2 mm / 2%) between original and CT images applied O-MAR. And 98.5% appeared in patient case, among original CT, O-MAR and density corrected CT. The difference of total dose distribution is less than 2% that appeared both phantom and patient case study. Though the dose deviations are little, there are still matters to discuss that the dose deviations are concentrated so locally. In this study, The quality of all images applied O-MAR was improved. Unexpectedly, Increase of max. HU was founded in air cavity of the O-MAR images compare to cavity of the original images and wrong corrections were appeared, too. Conclusion : The result of study assuming restrained case of O-MAR adapted to near skin and low density area, it appeared image distortion and artifact correction simultaneously. In O-MAR CT, air cavity area even turned tissue HU by wrong correction was founded, too. Consequentially, It seems O-MAR algorithm is not perfect to distinguish air cavity and photon starvation artifact. Nevertheless, the differences of HU and dose distribution are not a huge that is not suitable for clinical use. And there are more advantages in clinic for improved quality of CT images and DRRs, precision of contouring OARs or tumors and correcting artifact area. So original and O-MAR CT must be used together in clinic for more accurate treatment plan.