• Korean Journal of Acupuncture
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• v.21 no.3
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• pp.89-96
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• 2004

Objectives : In order to prove the effect of Phospholipase $A_2(PLA_2)$ Herbal-acupuncture, this experimental studies were performed by using rats that had neuronal damage due to the Middle Cerebral Artery Occulsion(MCAO). Methods : Microdialysis probes were implanted into the coordinate of striatum of anesthetized rats which consist of sham-operated 8 rats, MCAO-operated 8 rats and $PLA_2$ Herbal-acupuncture administrated 8 rats before MCAO operating. The $PLA_2$ Herbal-acupuncture(0.5mg/kg) was administrated to rats 30 minutes before having an operation causing the MCAO. The surgical excision lead the cross resected brain to the acute ischemic state. The brain was sliced in 2mm thickness and stained with cresyl violet buffer for the measurement of cerebral infarcted area and volume. Results : Based on the result of the tissue inspection for the cerebral ischemic cell, $PLA_2$ Herbal-acupuncture significantly protect neurocytes. Conclusions : We suggest $PLA_2$ Herbal-acupuncture produces protective effects against the neuronal damage induced by MCAO. Therefore, $PLA_2$ Herbal-acupuncture may prevent delayed neuronal death(DND) in selectively vulnerable focal areas of the brain effectively.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.93-98
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• 2020

The blends of Poly(lactic acid) (PLA) and Poly(butylene adipate-co-terephthalate) (PBAT) have been recognized as a replacement for commodity plastic films and bags in biodegradable packaging industries. The purpose of this study is to identify changes in the thermal and mechanical properties of PLA/PBAT blends with the addition of poly(ethylene oxide)(PEO). PLA (80%) and PBAT (20%) were melt mixed with 0 to 10 phr of PEO and processed using a hot press. The addition of PEO into PLA/PBAT increased the elongation at break and improved thermal stability. With PEO addition, two melting temperature (T_m) peaks of PLA/PBAT merged into one peak showing improved miscibility. The result of this study showed that the addition of PEO increased the ductility and thermal stability of PLA/PBAT blends.

• Biomedical Science Letters
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• v.18 no.1
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• pp.71-75
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• 2012

The PLA2G4A catalyzes the hydrolysis of membrane phospholipids to release arachidonic acid, which is metabolized into lipid-based cellular hormones that regulate inflammatory response. The circulating blood cell numbers can be influenced by stress, infection or inflammation. Quantitative blood cell count traits analysis for the 19 SNPs in the PLA2G4A gene in the Korean Association Resource (KARE) cohort (7551 subjects) was performed. The only one SNP (rs10752979) in the all blood cell count was satisfied with the Bonferroni corrected P-value (<0.00263). Furthermore, 6 of the 19 SNPs in the PLA2G4A gene showed a weak or moderate association with blood cell count (P-values: 0.0048~0.042), suggesting the clue of an association between the PLA2G4A gene and blood cell count, especially white blood cell count. This study may provide insight into the genetic basis of blood cell count related with reaction of infection.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.95-101
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• 2012

To manufacture of a completely biodegradable and compostable biomass -based blend polymer film, two types of cellulose acetates(DS=2.4 and DS=2.7) were blended with 5 - 50 wt% of low average molecular weight polylactide(PLA) by mixing each polymer solution having same viscosity in 10 wt% methanol/dichloromethane. Their surface morphology, thermal and mechanical properties were studied. The chemical structures of blend films were confirmed by the fourier transform IR spectroscopy with attenuated total reflection(FT-IR ATR) spectrophotometer. Scanning electron microscope(SEM) photos of blend films of both CAs with less than 5 % of PLA showed homogeneous morphology. On the contrary, the other blends with higher than 20 wt% of PLA content showed a large phase separation with spherical domains. The thermal property of blend films was also analyzed with thermogravimetric analysis(TGA) and differential scanning calorimeter(DSC). The tensile strength of CA/PLA blend films was increased up to $820kg_f/cm^2$ for TAC/PLA and $600kg_f/cm^2$ for DAC/PLA.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.1
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• pp.71-78
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• 1997

In an attempt to investigate the role of phospholipase $A_2$($PLA_2$) in interleukin-l (IL-l) induced acute lung injury, mepacrine was tried to inhibit $PLA_2$ in IL-l induced ARDS rats. For confirmation of acute lung injury by IL-l, and to know the role of neutrophils in this injury, lung leak index, lung myeloperoxidase(MPO), number of neutrophils and protein content in the bronchoalveolar lavage (BAL) and wet lung weight were measured. At the same time lung $PLA_2$ was measured to know the effect of IL-l on $PLA_2$ activity. Pulmonary surfactant was also measured for an investigation of type II alveolar cell function. Neutrophil adhesion assay was performed to know the effect of $PLA_2$ inhibition in vitro with human umbilical vein endothelial cells (HUVEC). For precise location of injury by IL-l, morpholgical study was performed by electron microscopy. Five hours after instillation of IL-l (50 ng/rat), lung leak index, protein content, number of neutrophils, lung MPO and wet lung weight were increased significantly. Five hours after IL-l instillation lung $PLA_2$ activity was increased significantly, and increased surfactant release was observed in IL-l induced ARDS rats' BAL. In contrast, in rats given mepacrine and IL-l, there was decrease of acute lung injury i.e. decrease of lung leak index, wet lung weight, protein content, number of neutrophils in BAL and decreased lung MPO activity. Mepacrine decreased surfactant release also. Interestingly, inhibition of $PLA_2$ decreased adhesion of human neutrophils to HUVEC in vitro. Morphologically, IL-l caused diffuse necrosis of endothelial cells, type I and II epithelial cells and increased the infiltration of neutrophils in the interstitium of the lung but after mepacrine treatment these pathological findings were lessened. On the basis of these experimental results it is suggested that $PLA_2$ has a major role in the pathogenesis of acute lung injury mediated by neutrophil dependent manner in IL-l induced acute lung injury.

• Textile Coloration and Finishing
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• v.34 no.3
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• pp.197-206
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• 2022

The purpose of this study was to confirm the optimal spinning conditions for PLA (Polylactic acid) as a fiber forming polymer. According to the melt spinning test results of PLA, the optimal spinning temperature was 258℃. However, it needs to note that relatively high pack pressure was required for spinning at 258℃. At an elevated temperature, 262℃, mono filament was broken easily due to hydrolysis of PLA at a higher temperature. In case of fiber strength, it was confirmed that the draw ratios of 2.7 to 3.3 were optimal for maximum strength of melt spun PLA. Above the draw ratio, 3.3, the strength of the PLA fibers was lowered. It was presumed that cleavage of the PLA polymer chain over maximum elongation. The heat setting temperature of GR (Godet roller) showed that the maximum strength of the PLA fibers was revealed around 100℃. The degree of crystallinity and the strength of the PLA fibers were decreased above 100℃. The optimal take-up speed (Spinning speed) was around 4,000m/min. Thermal analysis of PLA showed 170℃ and 57℃ as Tm (melting temperature) and Tg (glass transition temperature), respectively.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.323-324
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• 2003

생분해성 고분자 중에서 폴리락타이드 (poly(1-lactide), PLA)는 대량생산이 가능하기 때문에 많은 관심을 끌고 있다.[l,2] 그러나 상온에서 딱딱하고, 쉽게 가수분해가 일어나기 때문에 일반적인 용도로 다양하게 사용되기 위해서는 이런 단점이 개선되어야 한다. 본 연구에서는 생분해성 포장재료로 사용할 목적으로 PLA에 저밀도폴리에틸렌 (LDPE)를 혼합하여 PLA/LDPE 블렌드를 제조하였다. PLA/LDPE 블렌드는 비상용성이므로 이를 제어하기 위한 반응형 상용화제 첨가효과를 연구하였다. (중략)

• Journal of Chest Surgery
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• v.35 no.7
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• pp.501-510
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• 2002

Background: The various pathogeneses of acute respiratory distress syndrome have been suggested but not established yet. In the present study, the role of group II phospholipase $A_2$($PLA_2$) in the pathogenesis of gut ischemia-reperfusion(I/R) induced acute lung injury (ALI), especially in the pulmonary oxidative stress with infiltration of neutrophils was investigated. Material and Method: To induce ALI, reperfusion of mesentery was done for 120 min after clamping of superior mesenteric artery for 60 min in Sprague-Dawley rats that weighed about 300g. To exmaine the role of group II $PLA_2$ in ALI, especially endothelial injury associated with the action of neutrophils, lung myeloperoxidase activity, lung leak index, bronchoalveolar lavage fluid protein were measured, and pulmonary $PLA_2$ activity changes in gut I/R were also measured. The role of group II $PLA_2$in the neutrophilic generation of free radicals was assessed by inhibiting group II $PLA_2$ with rutin, manoalide and scalaradial. Furthermore, to verify the oxidative stress in the lung, histologic and free radical detecting cytochemical electron microscopy were done. Result: After reperfusion, ALI was developed with accumulation of neutrophils in the lung, which was confirmed by the increase of myeloperoxidase activity, lung leak index and bronchoalveolar lavage protein (p<0.001). The pulmonary and intestinal group II $PLA_2$ activities significantly increased after gut I/R which were reversed by rutin(p<0.001). In vitro, cytochrome-c reduction assay denoted the inhibitory effects of rutin, scalaradial and manoalide on the production of free radicals from isolated human neutrophils. Histologically, neutrophilic accumulation and pericapillary edema in the lung after gut I/R was detected by light microscopy which was suppressed by rutin. In $CeCl_3$ cytochemical electron microscopy, the increased production of hydrogen peroxide in the lung after gut I/R was confirmed and also the production of hydrogen peroxide was decreased by rutin. Conclusion: On the basis of these experimental results, the inhibition of group II $PLA_2$ seemed to mitigate gut I/R-induced ALI by suppressing the production of free radicals from the infiltrated neutrophils. Collectively, group II $PLA_2$ seems to play a crucial role in gut I/R-induced ALI by neutrophilic oxidative stress.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.198-199
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• 2003

Chronic inflammatory processes are associated with pathology of Alzheimer's disease(AD). The expression of both cyclooxygenase-2(COX-2) and phospholipase A2(PLA2) appears to be strongly activated during AD, indicating the importance of inflammatory gene pathways as a response to brain injury. Stimulation of heterotrimeric G protein-coupled receptors including muscarinic receptors activates cytosolic PLA2 and receptor-mediated activation of PLA2 generates free fatty acids (i.e., arachidonic acid). (omitted)

• The monthly packaging world
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• s.222
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• pp.58-63
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• 2011

포장재별로 처리한 콩나물의 저장 중 품질변화를 살펴보았다. 중량 감소율은 OPP필름에 비해 PLA 필름이 더 높은 것으로 나타났으나 0.025% 이하의 감소율로 큰 차이를 보이진 않았다. 수분함량의 경우 P3 포장구가 다른 처리구 보다 가장 적은 감소율을 보였으며, 총균수 변화에서는 P2, P3 포장구가 가장 적은 증가율을 나타내었으며, 외관상태에서 OPP 포장구는 봉투 개봉시 모든 포장구에서 부패취가 발생하였다. 비타민C 함량 변화는 PLA2 포장구가 변화율이 적었으며, PLA3 필름구가 그 다음으로 나타났으며, 기호도 조사에서는 PLA2 포장구가 모든 항목에서 높은 점수를 나타냈다. 결과적으로 OPP 포장구 보다는 PLA 포장구의 변화가 적었음을 알 수 있었으며, 그 중PLA2와 PLA3 필름이 콩나물 저장에 가장 효과적임을 알 수 있었다.