• Journal of Yeungnam Medical Science
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• v.3 no.1
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• pp.261-267
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• 1986

Development of supervoltage treatment machine may minimize skin reaction by skin-sparing effect, but skin damage is still one of "the dose limiting factor" in radiation therapy. In spite of these importance, systemic histopathologic studies of skin in similar conditions which used in clinical treatment has not been performed so far. 60mice were irradiated with conventional fraction ($200{\times}5/wk$) and whole abdominal field ($2{\times}3cm$, from symphysis pubis to xyphoid process). Used machine was 250KV, 24mA, orthovoltage x-ray machine. Histopathological changes of acute skin reaction at the level of total irradiation dose were analyzed and the possible mechanism of later chronic changes were investigated. Obtained results are as follows: 1. In 1,000 rad irradiated group, only mild epidermal edema is noted. 2. In 2,000 rad irradiated group, slightly decreased number and size of hair follicles and appendages, dermal edema and scanty infiltration of inflammatory cells are visible. 3. In 3,000 rad irradiated group, marked increased capillary congestion and prominant infiltration of inflammatory cells are observed. 4. In 4,000 rad irradiated group, vascular wall thickening with proliferation of endothelial cells are prominant. Dermal thinning and hyalinization are newly developed. 5. In 5,000 rad irradiated group, complete desquamation of epidermis is not seen, despite of acceleration of all above mentioned changes.

• Animal Bioscience
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• v.35 no.1
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• pp.126-137
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• 2022

Objective: Efficient gene editing technology is critical for successful knock-in in domestic animals. RAD51 recombinase (RAD51) gene plays an important role in strand invasion during homologous recombination (HR) in mammals, and is regulated by checkpoint kinase 1 (CHK1) and CHK2 genes, which are upstream elements of RAD51 recombinase (RAD51). In addition, mismatch repair (MMR) system is inextricably linked to HR-related pathways and regulates HR via heteroduplex rejection. Thus, the aim of this study was to investigate whether clustered regularly interspaced short palindromic repeats/CRISPR-associated 9 (CRISPR/Cas9)-mediated knock-in efficiency of human lactoferrin (hLF) knock-in vector in the bovine β-casein gene locus can be increased by suppressing DNA MMR-related genes (MSH2, MSH3, MSH6, MLH1, and PMS2) and overexpressing DNA double-strand break (DSB) repair-related genes (RAD51, CHK1, CHK2). Methods: Bovine mammary epithelial (MAC-T) cells were transfected with a knock-in vector, RAD51, CHK1, or CHK2 overexpression vector and CRISPR/sgRNA expression vector to target the bovine β-casein gene locus, followed by treatment of the cells with CdCl₂ for 24 hours. After 3 days of CdCl₂ treatment, the knock-in efficiency was confirmed by polymerase chain reaction (PCR). The mRNA expression levels of DNA MMR-related and DNA DSB repair-related genes were assessed by quantitative real-time PCR (RT-qPCR). Results: Treatment with CdCl₂ decreased the mRNA expression of RAD51 and MMRrelated genes but did not increase the knock-in efficiency in MAC-T cells. Also, the overexpression of DNA DSB repair-related genes in MAC-T cells did not significantly affect the mRNA expression of MMR-related genes and failed to increase the knock-in efficiency. Conclusion: Treatment with CdCl₂ inhibited the mRNA levels of RAD51 and DNA MMR-related genes in MAC-T cells. However, the function of MMR pathway in relation to HR may differ in various cell types or species.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.6
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• pp.1023-1033
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• 2020

Objective: The efficiency of the knock-in process is very important to successful gene editing in domestic animals. Recently, it was reported that transient loosening of the nucleosomal folding of transcriptionally inactive chromatin might have the potential to enhance homologous recombination efficiency. The objective of this study was to determine whether histone deacetylases (HDAC) inhibitor and RAD51 recombinase (RAD51) expression were associated with increased knock-in efficiency on the β-casein (bCSN2) gene locus in mammary alveolar-large T antigen (MAC-T) cells using the transcription activator-like effector nucleases (TALEN) system. Methods: MAC-T cells were treated with HDAC inhibitors, valproic acid, trichostatin A, or sodium butyrate for 24 h, then transfected with a knock-in vector, RAD51 expression vector and TALEN to target the bCSN2 gene. After 3 days of transfection, the knock-in efficiency was confirmed by polymerase chain reaction and DNA sequencing of the target site. Results: The level of HDAC 2 protein in MAC-T cells was decreased by treatment with HDAC inhibitors. The knock-in efficiency in MAC-T cells treated with HDAC inhibitors was higher than in cells not treated with inhibitors. However, the length of the homologous arm of the knock-in vector made no difference in the knock-in efficiency. Furthermore, DNA sequencing confirmed that the precision of the knock-in was more efficient in MAC-T cells treated with sodium butyrate. Conclusion: These results indicate that chromatin modification by HDAC inhibition and RAD51 expression enhanced the homologous recombination efficiency on the bCSN2 gene locus in MAC-T cells.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.71-71
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• 2003

The study on magnetic field combined radiation therapy, as a new technique to modify the dose distributions using external magnetic field, has been investigated. The goal of the study is to develop the techniques for dose localization, as a particle beam, from the strong magnetic fields. In this study, in order to study the principle of dose deposition in external fields, as a basic approach, we have calculated approximately the paths of traveling electrons in water under external magnetic fields with numerical methods. The calculations are performed for a primary particle by cumulating the steps which are defined as small path lengths which energy loss can be ignored. In this calculation, the energy loss and direction change for a step was calculated by using total stopping power and Lorentz force equation respectively. We have examined the deflected paths of the electron through water as a function of external magnetic field and incident electron s energy. Since we did not take account of the multiple scattering effects for electrons through water, there are errors in this calculation. However, from the results we can explain the principle of dose variation and dose focusing for electron beams under strong magnetic fields in water.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10457-10462
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• 2015

Homologous recombination repair (HRR) plays an important role in protection against carcinogenic factors. Genes regulating the HRR mechanisms may impair their functions and consequently result in increased cancer susceptibility. RAD 51 and XRCC3 are key regulators of the HRR pathway and genetic variability in these may contribute to the appearance and progression of various cancers including head and neck cancer (HNC). The aim of the present study was to compare the distribution of genotypes of RAD51 (135G/C, 172 G/T) and XRCC3 (Thr241Met) polymorphisms between HNC patients and controls. Each polymorphism was genotyped using the polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP) technique in 200 pathologically confirmed HNC patients along with 150 blood samples from normal, disease free healthy individuals. We observed that homozygous variant CC genotype of RAD51 135G/C was associated with a 2.5 fold increased HNC risk (OR=2.5; 95%CI=0.69-9.53; p<0.02), while second polymorphism of RAD 51 172 G/T, heterozygous variant GT genotype was associated with a 1.68 fold (OR=1.68; 95%CI=1.08-2.61; p<0.02) elevation when compared with controls. In the case of the Thr241Met polymorphism of XRCC3, we observed a 16 fold (OR=16; 95% CI=3.78-69.67; p<0.0002) increased HNC risk in patients compared to controls. These results further suggested that RAD51 (135G/C, 172 G/T) and XRCC3 (Thr241Met) polymorphisms may be effective biomarkers for genetic susceptibility to HNC. Larger studies are needed to confirm our findings and identify the underlying mechanisms.

• Journal of the Korean Society of Radiology
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• v.6 no.2
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• pp.99-106
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• 2012

The radioprotective effects of white ginseng and Entomopathogenic Fugi Extract on liver damage induced by X-ray were investigated. To one group of ICR male mice were given white ginseng(150 mg/kg/day for 7days, orally) and Entomopathogenic Fugi (200 mg/kg/day for 7days, orally) before X-ray irradiation. To another group were irradiated by 5 Gy(1.01 Gy/min) dose of X-ray. Contrast group were given with saline(0.1 ml). The levels of reduced(GSH) and oxidized(GSSG) glutathione in liver tissue were measured. The ratio of GSSG/total GSH was significantly decreased in the white ginseng and Entomopathogenic Fugi (200 mg/kg/day)(150 mg/kg/day) groups than irradiation group.

• Journal of radiological science and technology
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• v.47 no.2
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• pp.87-95
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• 2024

Most knee axial radiographs, known as sunrise and skyline view, were performed with the patient in the prone position. The authors tried to address some of the shortcomings of conventional radiography by developing a new radiography method, K-RAD. According to previous research, the K-RAD method showed a wider patellar-femoral joint space than conventional radiography and provided a clear patellar hemi-lateral image with a constant gap between the femoral trochlear groove and tibial tuberosity. The authors worked with an orthopedic specialist to perform radiography using the K-RAD method rather than using existing methods, and as a result, the two knees were aligned correctly and a clear image of the patellar-femoral joint space was created. The authors propose the K-RAD method for knee axial radiography because the K-RAD method provides a sense of stability to the patient and provides images with high diagnostic value.

• Clinical and Experimental Pediatrics
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• v.46 no.6
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• pp.554-560
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• 2003

Purpose : To investigate the teratogenic effect of gamma-ray on the heart of chick embryo. Methods : 50 rad, 100 rad, 150 rad, 200 rad, 250 rad, and 300 rad of gamma-ray were used to irradiate three days old chick embryos. The control group was not irradiated. After three weeks, the embryos were sacrificed and examined for cardiovascular malformation. Results : The survival rate of the gamma-ray irradiated group was significantly lower than that of the control group(33.3-63.3% vs 76.4%, P=0.001). The cardiac malformation rate of the experimental group was 11.0%. In the control group, no congenital cardiac malformations were observed. The experimental groups had a significantly higher malformation rate(P=0.001). The types of malformation were ventricular septal defect, tricuspid atresia, Ebstein anomaly and aortic arch anomaly. In the gamma-ray irradiated group, the cardiac malformations were : 14 small ventricular septal defects (VSDs), five large VSDs, two tricuspid atresias, and one Ebstein anomaly. The higher the dose of radiation applied, the higher the incidence of cardiac malformation was noted. Conclusion : Gamma-ray irradiation of 3 days old chick embryos increased the rate of death and the rate of cardiac malformation significantly.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.243-249
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• 2007

The centromere is a highly differentiated structure of the chromosome that fulfills a multitude of essential mitotic and meiotic functions. Alphoid DNA (${\alpha}$-satellite) is the most abundant family of repeated DNA found at the centromere of all human chromosomes, and chromosomes of primates in general. The most important parts in the development of Human Artificial Chromosomes (HACs), are the isolation and maintenance of stability of centromeric region. For isolation of this region, we could use the targeting hook with alphoid DNA repeat and cloned by Transformation-Associated Recombination (TAR) cloning technique in yeast Saccharomyces cerevisiae. The method includes rolling-circle amplification (RCA) of repeats in vitro to 5 kb-length and elongation of the RCA products by homologous recombination in yeast. Four types of $35\;kb{\sim}50\;kb$ of centromeric DNA repeat arrays (2, 4, 5, 6 mer) are used to examine the stability of repeats in homologous recombination mutant strains (rad51, rad52, and rad54). Following the transformation into wild type, rad51 and rad54 mutant strains, there were frequent changes in inserted size. A rad52 mutant strain showed extremely low transformation frequency, but increased stability of centromeric DNA repeat arrays at least 3 times higher than other strains. Based on these results, the incidence of large mutations could be reduced using a rad52 mutant strain in maintenance of centromeric DNA repeat arrays. This genetic method may use more general application in the maintenance of tandem repeats in construction of HAC.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.145-156
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• 2007

The purposes of this study were to investigate kinematic parameters of racket head and upper extremities during squash back hand stroke and to provide quantitative data to the players. Five Korean elite male players were used as subjects in this study. To find out the swing motion of the players, the land-markers were attached to the segments of upper limb and 3-D motion analysis was performed. Orientation angles were also computed for angular movement of each segment. The results were as follows. 1) the average time of the back hand swing (downswing + follow-through) was 0.39s (0.24 s + 0.15 s). 2) for each event, the average racket velocity at impact was 11.17m/s and the velocity at the end of swing was 8.03m/s, which was the fastest swing speed after impact. Also, for each phase, 5.10m/s was found in down swing but 7.68m/s was found in follow-through. Racket swing speed was fastest after the impact but the swing speed was reduced in the follow-through phase. 3) in records of average of joints angle, shoulder angle was defined as the relative angle to the body. 1.04rad was found at end of back swing, 1.75rad at impact and it changes to 2.35 rad at the end of swing. Elbow angle was defined as the relative angle of forearm to upper arm. 1.73rad was found at top of backswing, 2.79rad at impact, and the angle was changed to 2.55rad at end of swing. Wrist angle was defined as the relative angle of hand to forearm. 2.48rad was found at top of backswing, 2.86rad at impact, and the angle changes to 1.96rad at end of swing. As a result, if the ball is to fly in the fastest speed, the body has to move in the order of trunk, shoulder, elbow and wrist (from proximal segment to distal segment). Thus, the flexibility of the wrist can be very important factor to increase ball speed as the last action of strong impact. In conclusion, the movement in order of the shoulder, elbow and the wrist decided the racket head speed and the standard deviations were increased as the motion was transferred from proximal to the distal segment due to the personal difference of swing arc. In particular, the use of wrist (snap) may change the output dramatically. Therefore, it was concluded that the flexible wrist movement in squash was very important factor to determine the direction and spin of the ball.