Hyung Wook Park

Conjugation of the photosensitizer Chlorin e6 to pluronic F127 for enhanced cellular internalization for photodynamic therapy.

To improve the cellular internalization and tumor-specific targeting efficiency of a photosensitizer, Chlorin e6 (Ce6), was conjugated to Pluronic F127(®) (PF127) by esterification between the carboxylic groups of Ce6 and the two hydroxyl groups of PF127 (PCe6). After conjugation, two different PCe6 conjugates, PF127/Ce6 (PCe6-1) and Ce6/PF127/Ce6 (PCe6-2), were obtained and separated by hydrophobic interaction chromatography. In this study, PCe6-1 was employed because it has good solubility in aqueous media. The singlet oxygen generation (SOG) efficiency and fluorescence activity of PCe6-1 in aqueous media dramatically increased compared to free Ce6. Moreover, confocal imaging and fluorescence-activated cell sorting (FACS) analysis confirmed its enhanced internalization rate in mouse colon tumor (CT-26) cells. After light irradiation, the cellular phototoxicity of PCe6-1 against CT-26 was approximately 3 times higher than that of free Ce6 in vitro. Furthermore, PCe6-1 exhibited enhanced tumor-specific distribution and tumor growth inhibition after intravenous injection into tumor-bearing mice. These results suggest that PCe6-1 is a good candidate as a photosensitizer due to its high cellular internalization rate and tumor targeting efficiency.

Sequential Therapy for Helicobacter pylori Infection in Korea: Systematic Review and Meta-Analysis

Background/Aims Sequential therapy (ST) for Helicobacter pylori infection in countries other than Korea has shown higher eradication rates than triple therapy (TT). The aim of this study was to evaluate the efficacy of ST in Korea by performing a meta-analysis. Methods We performed a comprehensive literature search on the efficacy of ST as a first-line therapy. The odds ratios (ORs) of eradicating H. pylori infection after ST compared with TT were pooled. Pooled estimates of the eradication rates of ST and TT were also calculated. Results A total of six studies provided data on 1,759 adult patients. The ORs for the intention to treat (ITT) and the per-protocol (PP) eradication rate were 1.761 (95% confidence interval [CI], 1.403 to 2.209) and 1.966 (95% CI, 1.489 to 2.595). Pooled estimates of the ITT and PP eradication rate were 79.4% (95% CI, 76.3% to 82.2%) and 86.4% (95% CI, 83.5% to 88.8%), respectively, for the ST group, and 68.2% (95% CI, 62.1% to 73.8%) and 78.9% (95% CI, 68.9% to 81.7%), respectively, for the TT group. Conclusions Although ST presented a higher eradication rate than TT in Korea, the pooled eradication rates were lower than expected. Further studies are needed to validate ST as a first-line treatment for H. pylori in Korea.

Lipase-Sensitive Transfersomes Based on Photosensitizer/Polymerizable Lipid Conjugate for Selective Antimicrobial Photodynamic Therapy of Acne.

Acne vulgaris is a common skin problem affecting nearly 90% of adolescents and its development is associated with a colonization of Propionibacterium acnes (P. acnes). Although antibiotics have commonly been used to treat acne, antibiotic resistance of P. acnes is an emerging issue to be solved. In this study, a new way of photodynamic acne therapy is developed using P. acnes lipase-sensitive transfersome (DSPE-PEG-Pheo A (DPP) transfersome). For enhanced selectivity and skin penetration efficiency, DPP transfersomes are prepared from 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000], pheophorbide A (Pheo A), cholesterol, and Tween-80. Incorporation of Tween-80 as an edge activator increases the deformability of DPP transfersomes, enhancing skin penetration efficiency to four times that of free Pheo A. The photoactivity of Pheo A quenched by DPP transfersomes is gradually recovered by selective cleavage of the ester linkage in DPP transfersomes by P. acnes lipases. In vitro P. acnes-specific photoactivity and subsequent selective antimicrobial effect exhibit a greater than 99% loss of P. acnes viability. In vivo antiacne therapeutic effect is confirmed by reduction of swelling volume and thickness of P. acnes-induced nude mice skin. These results demonstrate that DPP transfersome-mediated photodynamic therapy can be used as an alternative method to treat bacterial skin infections.

The Transient Intermediate Plexiform Layer, a Plexiform Layer-like Structure Temporarily Existing in the Inner Nuclear Layer in Developing Rat Retina

The retina is a highly specialised part of the brain responsible for visual processing. It is well-laminated; three layers containing five different types of neurons are compartmentalised by two synaptic layers. Among the retinal layers, the inner nuclear layer (INL) is composed of horizontal, bipolar, and amacrine cell types. Bipolar cells form one sublayer in the distal half of the IPL, while amacrine cells form another sublayer in the proximal half, without any border-like structure. Here, we report that a plexiform layer-like structure exists temporarily in the border between the bipolar and amacrine sublayers in the INL in the rat retina during retinal development. This transient intermediate plexiform layer (TIPL) appeared at postnatal day (PD) 7 and then disappeared around PD 12. Most apoptotic cells in the INL were found near the TIPL. These results suggest that the TIPL may contribute to the formation of sublayers and the cell number limit in the INL.