• Polymer(Korea)
• /
• v.33 no.3
• /
• pp.213-218
• /
• 2009

A cationic lipid emulsion containing 1,2-dioleoyl-3-trimethylammonium-propane(DOTAP), Tween80, squalene has been prepared as a gene delivery system. In order to increase the transfection efficiency of gene carrier, folate was used as the tumor-targeting ligand that was attached on PEG-DPPE. HeLa and 293 cells were used for the in vitro transfection experiment. HeLa cell is a folate-positive cell line. The mean particle sizes of polymeric lipid system and DNA/lipid complex system were 206.6 nm and 150.5 nm, respectively. The transfection efficiencies of our carriers(4:l(w:w) complex ratio)were 100 times higher than that of DOTAP only emulsion due to the targeting effect of folate.

• Biomedical Science Letters
• /
• v.2 no.2
• /
• pp.211-222
• /
• 1996

The conceptus which are resulted by mating between two genetically non-identical partners can be considered to be an allograft to the mother science which is not rejected by the mother's immunological attack. The present studies have been, therefore, attempted in order to elucidate the mechanism by which protection of the fete-placental allograft, between the C3H/HeJ female mouse and DBA/2 male mouse occurred. For this purpose, firstly systemic immunity was investigated by measuring T and B lymphocytes subsets. Natural killer cell activity in maternal splenic tissue and by observing the effects of pregnancy serums, progesterone and hCG on immune systems. Secondly, local immunity also investigated by measuring T lymphocytes subsets, natural killer cell activity in lymph nodes draining the uterus. The subsets of Thy-1.2$^+$ cells and L 3T4$^+$ cells decreased slightly while the subsets of Ly2$^+$ cell increased significantly compared with those of the control group beyond the mid-gestational stage. The subsets of B cell gradually in-creased from the mid-gestational stage untill delivery. The natural killer cell activity in the maternal splenic tissue significantly increased during the period of 5th to 8th day of gestation. The natural killer cell activity was significantly suppressed by the pregnancy serums and non-pregnant serums compared with those of serum-free group. The treatment of hCG significantly suppressed natural killer cell activity in the dose dependent manner (1 unit/ml-1000 unit/ml) while pro-gesterone increased the natural killer cell activity at phamarcological dose only. In the lymph nodes draining the uterus, the subsets of Thy-1.2$^+$ cells significantly increased during the period of implantation and L3T4$^+$ cell subsets slightly increased during the mid-gestational stage. The subsets of Ly2$^+$ cell increased significantly during the mid-gestational stage, but decreasing slightly be-fore delivery. The natural killer cell activity was significantly elevated after the implantation period in the lymph nodes draining the uterus. The natural killer cell activity of the lymph nodes draining the uterus was higher than those of splenic tissue during the same periods of gestation. It is therefore, concluded that during the pregnancy, the phenomena which the fete-placental allograft has not been rejected and rather protected from the maternal immunological attack might be due to local immune suppression in fete-maternal interface tissues rather than systemic immune suppression. And the subsets of Thy-1.2$^+$ cells and L3T4$^+$ cells mainly contribute to accepting allograft in early stage of pregnancy, while the subsets of Ly2$^+$ cell and the subsets of B cell increased significantly compared with those of the control group beyond the mid-gestational stage, so their role in systemic immunity and local immunity gradually increased from the mid-gestational stage until delivery.

• Archives of Pharmacal Research
• /
• v.25 no.1
• /
• pp.1-10
• /
• 2002

Attempts to develop drugs, specific for cancer cells, are dealt here according to the intended cell-target. While many target specific drugs were developed, they reach only moderate successes in clinics for reasons, such as, delivery problem, lack of in vivo efficacy or toxicity. However, recent efforts focusing on the diversity of tyrosine kinases, participating in cell-signal transduction, brought fruit. The first such drug, Givec, approved by the USFDA recently, is used in clinics with great success to threat CML. The drug inhibits tyrosin kinase of bcr-abl, c-abl and v-abl. Work is progressing on other tyrosin kinase inhibitors and on other type of specific cancer cell signal protein inhibitors. These efforts are hoped to yield better cures for cancer in the near future.

• Journal of Electrochemical Science and Technology
• /
• v.14 no.1
• /
• pp.38-50
• /
• 2023

Proton exchange membrane fuel cell (PEMFC) is a portable and clean power generation device. The structural arrangement of the flow field has a significant influence on the delivery efficiency of PEMFC. In this article, a new bionic flow channel is designed based on the inspiration of a spider shape. The branch channel width and branch corner are studied as the focus, and its simulation is carried out by the method of computational fluid dynamics (CFD). The results show that when channel width/rib width and corner of the branch are 1.5 and 130° , respectively, it is the best numerical combination and the cell comprehensive performance is excellent. The final model using this numerical combination is compared with the traditional flow channel model to verify the advancement of this scheme.

• The Korean Journal of Physiology and Pharmacology
• /
• v.17 no.1
• /
• pp.23-30
• /
• 2013

Neural stem cells (NSCs) have the ability to proliferate and differentiate into various types of cells that compose the nervous system. To study functions of genes in stem cell biology, genes or siRNAs need to be transfected. However, it is difficult to transfect ectopic genes into NSCs. Thus to identify the suitable method to achieve high transfection efficiency, we compared lipid transfection, electroporation, nucleofection and retroviral transduction. Among the methods that we tested, we found that nucleofection and retroviral transduction showed significantly increased transfection efficiency. In addition, with retroviral transduction of Ngn2 that is known to induce neurogenesis in various types of cells, we observed facilitated final cell division in rat NSCs. These data suggest that nucleofection and retroviral transduction provide high efficiency of gene delivery system to study functions of genes in rat NSCs.

• Applied Microscopy
• /
• v.38 no.2
• /
• pp.73-79
• /
• 2008

In Biology, Studies Using Electron Microscopy for making Cell Structure to 3D reconstruction very fast development. Recently, by using Cryo fixation, we can see cell 3D structure without structural change, instead of using chemical fixation which can change cell structure. Before using this technology, we could understand cell structures only in 2D images. But now, through cryo-ET, 3D reconstruction of cell structure without artificial structure changes can be possible and this technology will give us many advantages in Drug delivery and Nanothechnology.

• Journal of Veterinary Science
• /
• v.21 no.3
• /
• pp.42.1-42.22
• /
• 2020

Regenerative medicine using stem cells from various sources are emerging treatment modality in several refractory diseases in veterinary medicine. It is well-known that stem cells can differentiate into specific cell types, self-renew, and regenerate. In addition, the unique immunomodulatory effects of stem cells have made stem cell transplantation a promising option for treating a wide range of disease and injuries. Recently, the medical demands for companion animals have been rapidly increasing, and certain disease conditions require alternative treatment options. In this review, we focused on stem cell application research in companion animals including experimental models, case reports and clinical trials in dogs and cats. The clinical studies and therapeutic protocols were categorized, evaluated and summarized according to the organ systems involved. The results indicate that evidence for the effectiveness of cell-based treatment in specific diseases or organ systems is not yet conclusive. Nonetheless, stem cell therapy may be a realistic treatment option in the near future, therefore, considerable efforts are needed to find optimized cell sources, cell numbers and delivery methods in order to standardize treatment methods and evaluation processes.

• Journal of Pharmaceutical Investigation
• /
• v.38 no.1
• /
• pp.31-38
• /
• 2008

The objective of this work is to study transdermal delivery of levodopa using iontophoresis and evaluate various factors which affect the transdermal transport. Levodopa is unstable in aqueous solution, and, in order to establish a stable condition for levodopa for the duration of experiment, we investigated the stability of levodopa in aqueous solutions of different pHs with/without the addition of dextrose or the application of current. Using stable aqueous solution, we have studied the effect of pH, polarity and penetration enhancer (ethanol) on transdermal flux and compared the results. We also investigated the iontophoretic flux from hydroxypropyl cellulose (HPC) hydrogel. In vitro flux study was performed at $33^{\circ}C$, using side-by-side diffusion cell. Full thickness hairless mouse skin and rat skin were used for this work. Current densities applied were 0.4 or $0.6mA/cm^2$ and current was off after 6 hour application. Stability study showed that levodopa solution with a pH 2.5 or 4.5 maintained the initial concentration of levodopa for 24 hours with the addition of 5% dextrose. However, at pH 9.5, levodopa was unstable and 30 to 40% of levodopa degraded within 24 hours, even with the addition of 5% dextrose. Hydrogel swollen with dextrose added levodopa solution maintained about 97% of the initial concentration of levodopa for 13 days, when stored in $4^{\circ}C$. The application of current did not affect the stability of levodopa in hydrogel. Flux study from levodopa solution with pH 2.5 showed that cathodal delivery of levodopa was higher than passive or anodal delivery. When the pH of the donor solution was 4.5, anodal delivery of levodopa was higher than passive or cathodal delivery. These results seem to indicate that electroosmosis plays more dominant role than electrorepulsion in the flux of levodopa at pH 2.5, and the reverse situation applies for pH 4.5. The passive flux was unexpectedly high for the ionized levodopa. Similar to the results from aqueous solution, cumulative amount of levodopa transported trom HPC hydrogel by cathodal delivery was significantly higher than passive or anodal delivery. The treatment of 70% ethanol cotton ball by scrubbing increased passive, anodal and cathodal flux, with the largest increase for anodal flux. These results indicate that iontophoretic delivery of zwitterion such as levodopa is much complicated than that can be expected from small ionic molecules with single charge. The results also indicate that the balance between electroosmosis and electrorepulsion plays a very important role in the transport through skin.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.11a
• /
• pp.38.2-38.2
• /
• 2009

Regeration of natural tissuesor to create biological substitutes for defective or lost tissues and organs through the use of cells. In addition to cells and their porous, drugs are required to promote tissue regeneration. Therefore, the present studies were prepared using simvastatim loaded porous poly(lactide-co-glycolide) (PLGA) by double emulsion solvent evaporation water-in-oil-in-water technique (W/O/W) as drug delivery system strategies for injuring tissue. The resulting microspheres were evaluated for morphology, particle size, encapsulation efficiency, degradation of PLGA microspheres in vitro drug release and in vitro cell viability. Scanning electronic microscopic (SEM) showed that the porosities of the particles was changed by experimental conditions and cultured cells were attached well on porous microspheres surface. The X-ray diffraction (XRD) and differential scanning calometry (DSC) analysis indicate thatsimvastatim was highly dipersed in the microsphere at amorphousstate.

• Journal of Pharmaceutical Investigation
• /
• v.31 no.3
• /
• pp.181-184
• /
• 2001

The purpose of this study was to develop transdermal drug delivery system (TDDS) for the combination of physostigmine and procyclidine. The effects of various pressure sensitive adhesives (PSA) on the percutaneous absorption of procyclidine across hairless mouse skin were evaluated to select an appropriate PSA. In addition, the influences of various vehicles on the percutaneous absorption of procyclidine from PSA matrix across hairless mouse skin were evaluated using flow-through diffusion cell system at $37^{\circ}C$. Physostigmine did not have any influence on the permeation rate of procyclidine. The flux of procyclidine was the highest in silicone and PIB and was relatively lower in SIS, Acryl, and SBS adhesive matrices, however, their use was limited by the crystallization of the drug in the matrix. Among acrylic adhesives, the permeability of procyclidine was the highest from poly (ethylene oxide) grafted acrylic adhesive. Some enhancers show different enhancing effect depending on the drug, however, many of the tested enhancers showed enhancing effect for the permeation of both procyclidine and physostigmine to some extent. $Crovol^{\circledR}$ EP 40 showed the highest enhancing effect on the permeation of both compounds. The size of TDDS to provide required permeation rate was estimated to be $35\;cm^2$ based on available information.