• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.753-756
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• 2005

Rapid prototyping (RP) technologies are mainly performed by layered manufacturing (LM) process which manufactures 3D physical objects by depositing 2D sections in a direction. Thus, deformations are apt to occur in overhanging area of the RP processed part. Also, excessive adhesion between part and platform of the RP apparatus is generated. In order to prevent these problems, most of the RP technologies adopt support structure. Main element to support a part in the support structure is strand. In actual field, however, the number of strand is determined by the software operating reference guide or RP system operator's experience. In this paper, a methodology to determine the optimal strand spacing is presented through experiments and measurements for the SL part deformation by change of strand spacing and part weight in the support structure of the stereolithography.

• 대한관절경학회지
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• 제2권1호
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• pp.45-50
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• 1998

Recently, a variety of arthroscopic techniques have been reported for the treatment of the displaced tibial eminence fracture. The purpose of this study was to describe details of arthroscopic technique using pull-out wire and to evaluate the results. Eleven patients with irreducible type II and type III tibial eminence fractures underwent the arthroscopic reduction and internal fixation using double strand pull-out wiring. The anterior cruciate ligament tibial drill guide was utilized for the reduction of fracture and passage of the guide pins. The tibial eminence fracture was firmly fixed with double strand 26-gauge pull-out wire(0.45mm diameter). Fracture union was achieved at 7.2 weeks (range, six to eight weeks) after operation. All cases were united at the last follow-up. Subjectively, nine patients had no pain and no restriction of daily activities. Two patients with combined injuries had limitation of knee motion(10 to 130 degrees, respectively) and one patient showed mild anterior laxity. Early rehabilitation was enabled without loss of reduction and breakage of pull-out wire. The arthroscopic reduction and internal fixation using pull-out wire showed good results including early rehabilitation, early fracture union, minimal morbidity, and no requirement of the second operation for hard ware removal.

• Genomics & Informatics
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• 제19권4호
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• pp.47.1-47.12
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• 2021

Kaposi's sarcoma-associated herpesvirus (KSHV) is one of the few human oncogenic viruses, which causes a variety of malignancies, including Kaposi's sarcoma, multicentric Castleman disease, and primary effusion lymphoma, particularly in human immunodeficiency virus patients. The currently available treatment options cannot always prevent the invasion and dissemination of this virus. In recent times, siRNA-based therapeutics are gaining prominence over conventional medications as siRNA can be designed to target almost any gene of interest. The ORF57 is a crucial regulatory protein for lytic gene expression of KSHV. Disruption of this gene translation will inevitably inhibit the replication of the virus in the host cell. Therefore, the ORF57 of KSHV could be a potential target for designing siRNA-based therapeutics. Considering both sequence preferences and target site accessibility, several online tools (i-SCORE Designer, Sfold web server) had been utilized to predict the siRNA guide strand against the ORF57. Subsequently, off-target filtration (BLAST), conservancy test (fuzznuc), and thermodynamics analysis (RNAcofold, RNAalifold, and RNA Structure web server) were also performed to select the most suitable siRNA sequences. Finally, two siRNAs were identified that passed all of the filtration phases and fulfilled the thermodynamic criteria. We hope that the siRNAs predicted in this study would be helpful for the development of new effective therapeutics against KSHV.

• BMB Reports
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• 제52권8호
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• pp.475-481
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• 2019

The evolution of genome editing technology based on CRISPR (clustered regularly interspaced short palindromic repeats) system has led to a paradigm shift in biological research. CRISPR/Cas9-guide RNA complexes enable rapid and efficient genome editing in mammalian cells. This system induces double-stranded DNA breaks (DSBs) at target sites and most DNA breakages induce mutations as small insertions or deletions (indels) by non-homologous end joining (NHEJ) repair pathway. However, for more precise correction as knock-in or replacement of DNA base pairs, using the homology-directed repair (HDR) pathway is essential. Until now, many trials have greatly enhanced knock-in or substitution efficiency by increasing HDR efficiency, or newly developed methods such as Base Editors (BEs). However, accuracy remains unsatisfactory. In this review, we summarize studies to overcome the limitations of HDR using the CRISPR system and discuss future direction.

• BMB Reports
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• 제57권1호
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• pp.66-70
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• 2024

Prime editors (PEs), which are CRISPR-Cas9 nickase (H840A)-reverse transcriptase fusion proteins programmed with prime editing guide RNAs (pegRNAs), can not only edit bases but also install transversions, insertions, or deletions without both donor DNA and double-strand breaks at the target DNA. As the demand for in-locus tagging is increasing, to reflect gene expression dynamics influenced by endogenous genomic contexts, we demonstrated that PEs can be used to introduce the hemagglutinin (HA) epitope tag to a target gene locus, enabling molecular and biochemical studies using in-locus tagged plants. To promote genome-wide in-locus tagging, we also implemented a publicly available database that designs pegRNAs for in-locus tagging of all the Arabidopsis genes.

• BMB Reports
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• 제54권2호
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• pp.98-105
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• 2021

The clustered regularly interspaced short palindromic repeats (CRISPR) system is a family of DNA sequences originally discovered as a type of acquired immunity in prokaryotes such as bacteria and archaea. In many CRISPR systems, the functional ribonucleoproteins (RNPs) are composed of CRISPR protein and guide RNAs. They selectively bind and cleave specific target DNAs or RNAs, based on sequences complementary to the guide RNA. The specific targeted cleavage of the nucleic acids by CRISPR has been broadly utilized in genome editing methods. In the process of genome editing of eukaryotic cells, CRISPR-mediated DNA double-strand breaks (DSB) at specific genomic loci activate the endogenous DNA repair systems and induce mutations at the target sites with high efficiencies. Two of the major endogenous DNA repair machineries are non-homologous end joining (NHEJ) and homology-directed repair (HDR). In case of DSB, the two repair pathways operate in competition, resulting in several possible outcomes including deletions, insertions, and substitutions. Due to the inherent stochasticity of DSB-based genome editing methods, it was difficult to achieve defined single-base changes without unanticipated random mutation patterns. In order to overcome the heterogeneity in DSB-mediated genome editing, novel methods have been developed to incorporate precise single-base level changes without inducing DSB. The approaches utilized catalytically compromised CRISPR in conjunction with base-modifying enzymes and DNA polymerases, to accomplish highly efficient and precise genome editing of single and multiple bases. In this review, we introduce some of the advances in single-base level CRISPR genome editing methods and their applications.