Characterization of the major dehydrogenase related to d-lactic acid synthesis in Leuconostoc mesenteroides subsp. mesenteroides ATCC 8293

Li, L.,Eom, H.J.,Park, J.M.,Seo, E.,Ahn, J.E.,Kim, T.J.,Kim, J.H.,Han, N.S. IPC Science and Technology Press ; Elsevier Scienc 2012 Enzyme and microbial technology Vol.51 No.5

Leuconostoc mesenteroides subsp. mesenteroides ATCC 8293 is a lactic acid bacterium that converts pyruvate mainly to d-(-)-lactic acid by using d-(-)-lactate dehydrogenase (ldhD). The aim of this study was to identify the gene responsible for d-lactic acid formation in this organism and to characterize the enzyme to facilitate the production of optically pure d-lactic acid. A genomic analysis of L. mesenteroides ATCC 8293 revealed that 7 genes encode lactate-related dehydrogenase. According to transcriptomic, proteomic, and phylogenetic analyses, LEUM_1756 was the major gene responsible for the production of d-lactic acid. The LEUM_1756 gene, of 996bp and encoding 332 amino acids (36.5kDa), was cloned and overexpressed in Escherichia coli BL21(DE3) Star from an inducible pET-21a(+) vector. The enzyme was purified by Ni-NTA column chromatography and showed a specific activity of 4450U/mg, significantly higher than those of other previously reported ldhDs. The gel permeation chromatography analysis showed that the purified enzyme exists as tetramers in solution and this was the first report among lactic acid bacteria. The pH and temperature optima were pH 8.0 and 30<SUP>o</SUP>C, respectively, for the pyruvate reduction reaction, and pH 11.0 and 20<SUP>o</SUP>C, respectively, for the lactate oxidation reaction. The K<SUB>m</SUB> kinetic parameters for pyruvate and lactate were 0.58mM and 260mM, respectively. In addition, the k<SUB>cat</SUB> values for pyruvate and lactate were 2900s<SUP>-1</SUP> and 2280s<SUP>-1</SUP>, respectively. The enzyme was not inhibited by Ca<SUP>2+</SUP>, Co<SUP>2+</SUP>, Cu<SUP>2+</SUP>, Mg<SUP>2+</SUP>, Mn<SUP>2+</SUP>, Na<SUP>+</SUP>, or urea, but was inhibited by 1mM Zn<SUP>2+</SUP> and 1mM SDS.

Docetaxel-Loaded Polylactic Acid-Co-Glycolic Acid Nanoparicles: Formulatuin, Physicochemical Characterization and Cytotoxicity Studies

( Roshan Pradhan ),( Bijay Kumar Poudel ),( Thiruganesh Ramasamy ),( Han Gon Choi ),( Chul Soon Yong ),( Jong Oh Kim ) 영남대학교 약품개발연구소 2013 영남대학교 약품개발연구소 연구업적집 Vol.23 No.0

In the present study, we developed novel docetaxel (DTX)-loaded polylactic acid-co-glycolic acid(PLGA) nanoparticles (NPs) using the combination of sodium lauryl sulfate (SLS) and poloxamer 407, the anionic and non-ionic surfactants respectively for stabilization. The NPs were prepared by emulsification/solvent evaporation method. The combination of these surfactants at weight ratio of 1:0.5 was able to produce uniformly distributed small sized NPs and demonstrated the better stability of NP dispersion with high encapsulation efficiency (85.9 +/- 0.6%). The drug/polymer ratio and phase ratio were 2:10 and 1:10, respectively. The optimized formulation of DTX-loaded PLGA NPs had a particle size and polydispersity index of 104.2 +/- 1.5 nm and 0.152 +/- 0.006, respectively, which was further supported by TEM image. In vitro release study was carried out with dialysis membrane and showed 32% drug release in 192 h. When in vitro release data were fitted to Korsmeyer-Peppas model, the n value was 0.481, which suggested the drug was released by anomalous or non-Fickian diffusion. In addition, DTX-loaded PLGA NPs in 72 h, displayed approximately 75% cell viability reduction at 10 microg/ml DTX concentration, in MCF-7 cell lines, indicating sustained release from NPs. Therefore, our results demonstrated that incorporation of DTX into PLGA NPs could provide a novel effective nanocarrier for the treatment of cancer.

건 유착 형성에 미치는 Polylactic Acid 흡수성 Film의 효용성

박상원(Sang Won Park),백종륜(Jong Ryoon Baek),이순혁(Soon Hyuck Lee),정종원(Jong Won Chung),조형준(Hyung Joon Cho) 대한정형외과학회 2006 대한정형외과학회지 Vol.41 No.1

목적: 건 봉합술 후 생기는 건의 유착 방지에 polylaetic acid 성분의 bioresorbable film이 유용한지 알아보고자 하였다. 대상 및 방법: 가토 24마리(48예)의 저113족지에서 심 족지 굴근을 절단하고 건을 봉합한 후 조작없이 건막을 봉합한 군을 제1군, 건과 건막 봉합 후에 건과 건막 사이에 hyaluronic acid를 주입한 군을 제2군, 건 봉합 후 film을 봉합건 주위에 피복 시킨 후 건막 봉합 술을 시행한 군을 제3군으로 나누어 수술 후 1주, 2주, 3주 및 6주에 조직학적 소견 및 생역학적 평가를 하였다. 결과: 광학 현미경 소견에서 섬유화의 정도는 제1군에서 가장 뚜렷하였고 제2군과 제3군에서는 큰 차이를 보이지 않았다. 만능 시험기를 통한 생역학적 검사상 모든 군에서 시간이 경과할수록 유착력(adhesion strength)은 증가하였다. 술 후 6주에는 제1군이 2군 및 3군에 비해 약 2.5-3배의 유착력을 나타냈고 통계적으로 유의성이 있었으며 제2군이 제3군에 비해 다소 높은 유착력을 나타냈으나 통계적으로 의미있는 차이는 보이지 않았다. 결론: 건 봉합 후 건이 치유됨에 따라 육아조직의 증식과 섬유화가 일어남을 확인하였고 polylactide resorbable film이건 봉합 후 건 유착 방지에 효과가 있었다. Purpose: To evaluate the effectiveness of a polylactic acid bioresorbable film in the prevention of tendon adhesion after tendon repair. Materials and Methods: Twenty-four adult rabbits (48 cases) were used in this study. In the first (control) group, the flexor tendons of the third toe were cut and a tenorrhaphy was performed. The 2nd group was injected with hyaluronic acid between the tendon and tendon sheath after suturing. The 3rd group underwent an enveloping of the tendon with polylactic acid film, followed by tenorrhaphy. The test animals were euthanized at 1, 2, 3, and 6 weeks after surgery, and the histology and biomechanics were evaluated. Results: Microscopic evaluations revealed fibrosis to be most apparent in group 1, while groups 2 and 3 showed no significant differences. The biomechanical tests, which were carried out using a Universal Testing Machine, revealed that an increase in adhesion strength with time. At 6 weeks after surgery, group 1 exhibited an adhesion strength that was 2.5-3 times greater than that exhibited by groups 2 and 3. Group 2 had a higher adhesion strength than group 3, but this difference was not statistically significant. Conclusion: Increases in granulation tissue and fibrosis during the healing of sutured tendons were observed, and the tested polylactide resorbable film was found to be effective in reducing the level of adhesion formation after tendon repair.

Polylactic Acid를 이용한 3D-printed 임시 수복물 제작 증례

송승례,정복영 대한통합치과학회 2023 대한통합치과학회지 Vol.12 No.2

This case report presents the clinical application of dental polylactic acid (PLA) interim prosthesis fabricated by fused deposition modeling (FDM) 3D printer and evaluates its clinical applicability as a substitute for conventional materials such as acrylic resin. FDM printed PLA interim prosthesis was applied in each case of the 3-unit bridge and the single crown in the maxillary posterior and mandibular posterior regions. After 10~14 days of short-term intraoral use, there was no deformation or fracture of the prosthesis and dissolution of the cement, and the patients were satisfied with the PLA prosthesis. The dimensional accuracy and flexural strength of PLA prosthesis are clinically acceptable for short-term use. However, due to surface roughness, esthetics can be reduced and plaque deposition can occur, requiring post-printing glazing and subsequent post-curing processes. The suitable polishing method for PLA prosthesis is currently unknown. Further study of output conditions such as nozzle diameter or layer thickness is required to print smooth surfaces, and increasing the heat resistance of the material to facilitate polishing can also be an improvement. FDM printed PLA interim prosthesis is noteworthy in a way that overcomes the disadvantages of polymerization shrinkage, marginal gap formation, tissue irritation of monomer, and patient discomfort that occur in the intraoral direct method using polymethyl methacrylate (PMMA), a conventional material. Glazing liquid application is necessary to enhance surface roughness.

Efficient production of polylactic acid and its copolymers by metabolically engineered Escherichia coli

Jung, Y.K.,Lee, S.Y. Elsevier Science Publishers 2011 Journal of biotechnology Vol.151 No.1

Polylactic acid (PLA) is one of the promising biodegradable polymers, which has been produced in a rather complicated two-step process by first producing lactic acid by fermentation followed by ring opening polymerization of lactide, a cyclic dimer of lactic acid. Recently, we reported the production of PLA and its copolymers by direct fermentation of metabolically engineered Escherichia coli equipped with the evolved propionate CoA-transferase and polyhydroxyalkanoate (PHA) synthase using glucose as a carbon source. When employing these initially constructed E. coli strains, however, it was necessary to use an inducer for the expression of the engineered genes and to feed succinate for proper cell growth. Here we report further metabolic engineering of E. coli strain to overcome these problems for more efficient production of PLA and its copolymers. This allowed efficient production of PLA and its copolymers without adding inducer and succinate. The finally constructed recombinant E. coli JLXF5 strain was able to produce P(3HB-co-39.6mol% LA) having the molecular weight of 141,000Da to 20gl<SUP>-1</SUP> with a polymer content of 43wt% in a chemically defined medium by the pH-stat fed-batch culture.

Study on the effect of compatibilizer on various properties of Polylactic acid/Polypropylene blending systems

김충희,민병각 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Various properties including thermal and mechanical properties of polylactic Acid(PLA) 20wt% / Polypropylene(PP) 80wt% blending systems were studied in terms of compatibilizer content in the range of 2 to 10 phr. The PLA 20wt% / PP 80wt% blending systems containing different content of compatibilizer were prepared by using twin screw extruder. The compatibilizer used in this experiment is BPMS-250 which is commercially available. Thermal properties of the blending systems containing different content of compatibilizer were investigated by using DSC and TGA analysis. Mechanical properties including tensile and flexural properties were measured by using universal test machine. The obtained thermal and mechanical property data were interpreted in terms of the content of compatibilizer. ** This was supported by Korea National University of Transportation in 2019.

Characterization of Polylactic Acid/Polypropylene blending Systems

문성준,민병각 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

The Polylactic Acid(PLA)/Polypropylene(PP) blending systems were prepared by using an extrusion molding technique at the extrusion temperature of 210°C. In order to investigate the mechanical and thermal properties of PLA/PP blending systems as a function of PLA concentration, PLA content were varied in the range of 0 to 100wt%. For mechanical properties tensile and flexural tests were carried out, and heat distortion temperature was measured for thermal characterization. In addition, the fractured surface of the blending systems was observed by using a scanning electron microscope for phase separation studies. All the property data obtained are presented and interpreted in terms of PLA content. ^** This was supported by Korea National University of Transportation in 2018.

PLA/PGA 차폐막과 실크 피브로인 차폐막을 이용한 발치와의 골유도재생술의 비교연구

황우진,정성념,김윤상,피성희,유형근,정종평,신형식,Hwang, Woo-Jin,Jeong, Seong-Nyum,Kim, Yun-Sang,Pi, Sung-Hee,You, Hyung-Keun,Chung, Chong-Pyoung,Shin, Hyung-Shik 대한치주과학회 2009 Journal of Periodontal & Implant Science Vol.39 No.2

Purpose: This study was designed to compare the bond regeneratiom effects of treatment using silk fibroin membrane ( Nanogide-S$^{(R)}$ ) resorbable barrier with control group treated by polyactic acid / polylacticglycolic acid membrane(Biomesh$^{(R)}$ ) Methods: 44 severe bone loss on extraction socket from 44 patients were used in this study. In experimental group 22 sites of them were treated by silk fibrin membrane as and the other 22 sites were treated by polyactic acid/ polylacticglycolic acid membrane as a control group. Clinical parameters including recovered bone width, length and radiographic parameter of vertical length were evlauated at base line and 3 months after surgery. Results: 1) Severe bone width, length was significantlly decreased in two group. 2) Bone width, length was significantlly decreased in two group. 3) Decreased bone width, length and radiographic examination differences between group. Conclusions: On the basis of these results, silk fibrin resorbable membrane has similar bone regeneration ability to polyactic acid / polylacticglycolic acid membrane in guided bone regeneration for severe bone loss defect on extraction socket.

비중격 외비성형술에서 이식 재료로써 Polylactic-Co-Glycolic Acid Plate의 유용성

강재윤,김민수,임세연,박수경,나기상,김용민 대한이비인후과학회 2021 대한이비인후과학회지 두경부외과학 Vol.64 No.9

Background and Objectives Polylactic-co-glycolic acid (PLGA) plate has been recognizedfor its biocompatibility and biomechanical properties and used widely in various clinicalfields. The aim of this study was to evaluate the usefulness and reliability of PLGA plate as agraft material in septorhinoplasty. Subjects and Method Medical records were retrospectively analyzed for patients who underwentseptorhinoplasty including extracorporeal septoplasty from January 2017 to June 2020. We evaluated demographics, diagnosis, operation techniques, and complications of PLGA plateas a graft material used in these patients. Results A total of 33 patients were enrolled in this study. Twenty-eight were male and 5 werefemale. The median age was 32 years old. The follow-up period after surgery was 6-32 months,and the mean follow-up period was 18.03 months. The PLGA plate was used in unilateralspreader graft (n=17), bilateral spreader graft (n=10), batten graft (n=3), strengthening of septalextension graft (n=2) and columellar strut graft (n=3), and fixing L-strut during extracorporealseptoplasty (n=12). During the follow-up period, no patient experienced extrusion orexposure of the grafts. Mild complications, such as redness of the columella skin, granulationin the marginal incision site, and pain on the nasal dorsum were observed in three patients;these complications were temporary and patients improved with conservative treatments. Conclusion The PLGA plate may be a useful graft material in correcting deviated nose especiallywhen the harvested septal cartilage is insufficient and if used carefully in limited locationssuch as L-strut and columella.

Reactive blending of polylactic acid/polyethylene glycol toward biodegradable film

Ali Salimi,Shervin Ahmadi,Mona Faramarzi,Jalal Faghihi 한국고분자학회 2023 Macromolecular Research Vol.31 No.9

Polyethylene glycol (PEG) was first modified with bis(trimethoxysilylpropyl) amine as an effective coupling agent. Different compositions of PEG and polylactic acid (PLA) were then prepared through melt blending. The silane modification of PEG was confirmed by infrared spectroscopy. The SEM micrographs of different PEG/PLA compositions showed rather homogenous single phase morphology in the compositions with silane-modified PEG. The efficacy of silane-modified PEG maybe due to interfacial compatibilization of PLA and the silane-modified PEG. According to TGA and DSC thermograms, the PEG loading into PLA resulted in somewhat higher thermal stability and increase in the degree of crystallinity of up to 52%. The dynamic mechanical thermal analysis showed lower glass transition temperatures and higher toughness for all the silane-modified PEG/PLA compositions than that of the neat PLA. The biodegradation behavior of silane-modified PEG/PLA compositions increased linearly as evidenced by material weight loss either in water absorption or fungi associated destruction tests.