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Characterization of Synthetic Polyamides by MALDI-TOF Mass Spectrometry
Haeyoung Choi,최은경,Eun Kyung Yang,Sungwoo Jang,Chan Ryang Park* 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.12
MALDI-TOF-MS technique was applied to obtain structural and compositional information of synthetic polyamides, Nylon6 and Nylon66. Mass spectra of both the original and the hydrolyzed polyamide samples were analyzed using the self calibration method as well as the internal calibration method with the standard materials of known masses. The MALDI-TOF mass spectra of Nylon6 samples showed the presence of protonated, sodiated, and potassiated ions that were assigned to cyclic and NH2/COOH terminated linear oligomers. From the MALDI-TOF mass spectra of Nylon66 samples, the potassiated linear oligomers with three different end groups are identified as well as the cyclic oligomers, i.e., NH2/COOH terminated oligomers, NH2/NH2 terminated oligomers, and COOH/COOH terminated oligomers. Full characterization of the molecular species and end groups present in the polyamide samples has been achieved, and also the changes in mass spectral patterns after the hydrolysis of the samples are presented.
Choi, Chan-Il,Yoon, Sang-Phil,Choi, Jung-Mi,Kim, Sung-Soo,Lee, Young-Don,Birnbaumer, Lutz,Suh-Kim, Haeyoung Nature Publishing Group 2014 Experimental and molecular medicine Vol.46 No.5
<P>The Cre/LoxP system is a well-established approach to spatially and temporally control genetic inactivation. The calcium/calmodulin-dependent protein kinase II alpha subunit (CaMKIIα) promoter limits expression to specific regions of the forebrain and thus has been utilized for the brain-specific inactivation of the genes. Here, we show that CaMKIIα-Cre can be utilized for simultaneous inactivation of genes in the adult brain and in male germ cells. Double transgenic Rosa26<SUP>+/stop-lacZ</SUP>::CaMKIIα-Cre<SUP>+/Cre</SUP> mice generated by crossing CaMKIIα-Cre<SUP>+/Cre</SUP> mice with floxed ROSA26 lacZ reporter (Rosa26<SUP>+/stop-lacZ</SUP>) mice exhibited lacZ expression in the brain and testis. When these mice were mated to wild-type females, about 27% of the offspring were whole body blue by X-gal staining without inheriting the Cre transgene. These results indicate that recombination can occur in the germ cells of male Rosa26<SUP>+/stop-lacZ</SUP>::CaMKIIα-Cre<SUP>+/Cre</SUP> mice. Similarly, when double transgenic Gnao<SUP>+/f</SUP>::CaMKIIα-Cre<SUP>+/Cre</SUP> mice carrying a floxed <I>Go-alpha</I> gene (Gnao<SUP>f/f</SUP>) were backcrossed to wild-type females, approximately 22% of the offspring carried the disrupted allele (Gnao<SUP>Δ</SUP>) without inheriting the Cre transgene. The Gnao<SUP>Δ/Δ</SUP> mice closely resembled conventional Go-alpha knockout mice (Gnao<SUP>−/−</SUP>) with respect to impairment of their behavior. Thus, we conclude that CaMKIIα-Cre mice afford recombination for both tissue- and time-controlled inactivation of floxed target genes in the brain and for their permanent disruption. This work also emphasizes that extra caution should be exercised in utilizing CaMKIIα-Cre mice as breeding pairs.</P>
Choi, Jung-Mi,Kim, Sung-Soo,Choi, Chan-Il,Cha, Hye Lim,Oh, Huy-Hyen,Ghil, Sungho,Lee, Young-Don,Birnbaumer, Lutz,Suh-Kim, Haeyoung National Academy of Sciences 2016 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.113 No.39
<P>In mammals, initial detection of olfactory stimuli is mediated by sensory neurons in the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). The heterotrimeric GTP-binding protein G(o) is widely expressed in the MOE and VNO of mice. Early studies indicated that G(o) expression in VNO sensory neurons is critical for directing social and sexual behaviors in female mice [Oboti L, et al. (2014) BMC Biol 12:31]. However, the physiological functions of G(o) in the MOE have remained poorly defined. Here, we examined the role of G(o) in the MOE using mice lacking the a subunit of G(o). Development of the olfactory bulb (OB) was perturbed in mutant mice as a result of reduced neurogenesis and increased cell death. The balance between cell types of OB interneurons was altered in mutant mice, with an increase in the number of tyrosine hydroxylase-positive interneurons at the expense of calbindin-positive interneurons. Sexual behavior toward female mice and preference for female urine odors by olfactory sensory neurons in the MOE were abolished in mutant male mice. Our data suggest that G(o) signaling is essential for the structural and functional integrity of the MOE and for specification of OB interneurons, which in turn are required for the transmission of pheromone signals and the initiation of mating behavior with the opposite sex.</P>
Choi, Haeyoung,Bae, YeoJi,Lee, Sang-Min,Ha, Yoon-Cheol,Shin, Heon-Cheol,Kim, Byung Gon The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.1
ANODE-free Li-metal batteries (AFLMBs) operating with Li of cathode material have attracted enormous attention due to their exceptional energy density originating from anode-free structure in the confined cell volume. However, uncontrolled dendritic growth of lithium on a copper current collector can limit its practical application as it causes fatal issues for stable cycling such as dead Li formation, unstable solid electrolyte interphase, electrolyte exhaustion, and internal short-circuit. To overcome this limitation, here, we report a novel dual-salt electrolyte comprising of 0.2 M LiPF<sub>6</sub> + 3.8 M lithium bis(fluorosulfonyl)imide in a carbonate/ester co-solvent with 5 wt% fluoroethylene carbonate, 2 wt% vinylene carbonate, and 0.2 wt% LiNO<sub>3</sub> additives. Because the dual-salt electrolyte facilitates uniform/dense Li deposition on the current collector and can form robust/ionic conductive LiF-based SEI layer on the deposited Li, a Li/Li symmetrical cell exhibits improved cycling performance and low polarization for over 200 h operation. Furthermore, the anode-free LiFePO<sub>4</sub>/Cu cells in the carbonate electrolyte shows significantly enhanced cycling stability compared to the counterparts consisting of different salt ratios. This study shows an importance of electrolyte design guiding uniform Li deposition and forming stable SEI layer for AFLMBs.
Nonlinear Absortption processes in Triphenyamine-dithienothiophene-Triphyenylamine
Haeyoung Choi,Myoungsik Cha,han-Young Woo,Jong-Hyup Lee,kwanghee Lee,Kwang-sup Lee,Oh-Kil Kim 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
We investigated the nonlinear absorption mechanism in the triphenylamine-dithienothiophenetriphenylamine molecule by using laser pulses with two different pulse widths, 7 ns and 35 ps. The single-beam transmission measurement with a 7-ns pulse resulted in a larger nonlinear absorption than that with a 35-ps pulse and saturated at high input intensities due to the excited state absorption (ESA) initiated by two-photon absorption (TPA). For a quantitative characterization of the TPA and ESA contributions to the nonlinear absorption, we estimated the ESA spectrum and lifetime by using a pump-probe transmission measurement with a 35-ps pulse. A 5-level model was used to explain both the nonlinear absorption and the one-photon and the two-photon pumped fluorescence.
Haeyoung Kim,Won Park,Su Ssan Kim,Sung Ja Ahn,Yong Bae Kim,Tae Hyun Kim,Jin Hee Kim,Jin-Hwa Choi,Hae Jin Park,Jee Suk Chang,Doo Ho Choi 대한방사선종양학회 2021 Radiation Oncology Journal Vol.39 No.2
Purpose: This study was conducted to evaluate prognosis of patients with level I/II axillary lymph node metastases from occult breast cancer (OBC). Materials and Methods: Data of 53 patients with OBC who received axillary lymph node dissection (ALND) positive/negative (+/-) breast-conserving surgery between 2001 and 2013 were retrospectively collected at seven hospitals in Korea. The median number of positive lymph nodes (+LNs) was 2. Seventeen patients (32.1%) had >3 +LNs. A total of 48 patients (90.6%) received radiotherapy. Extents of radiotherapy were as follows: whole-breast (WB; n = 11), regional lymph node (RLN; n = 2), and WB plus RLN (n = 35). Results: The median follow-up time was 85 months. Recurrence was found in four patients: two in the breast, one in RLN, and one in the breast and RLN. The 5-year and 7-year disease-free survival (DFS) rates were 96.1% and 93.5%, respectively. Molecular subtype and receipt of breast radiotherapy were significantly associated with DFS. Patients with estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor 2 negative (ER-/PR-/HER2-) subtype had significantly lower 7-year DFS than those with non-ER-/PR-/HER2- tumor (76.9% vs. 100.0%; p = 0.03). Whole breast irradiation (WBI) was significantly associated with a higher 7-year DFS rate (94.7% for WBI group vs. 83.3% for non-WBI group; p = 0.01). Other factors including patient’s age, number of +LNs, taxane chemotherapy, and RLN irradiation were not associated with DFS. Conclusion: Patients with OBC achieved favorable outcome after ALND and breast-targeting treatment. Molecular subtype and receipt of WBI was significant factors for DFS.
Kim, Haeyoung,Cho, Dae-Yeon,Choi, Doo Ho,Choi, Su-Youn,Shin, Inkyung,Park, Won,Huh, Seung Jae,Han, Sung-Hee,Lee, Min Hyuk,Ahn, Sei Hyun,Son, Byung Ho,Kim, Sung-Won,Haffty, Bruce G M. Nijhoff ; Kluwer Academic Publishers 2012 Breast cancer research and treatment Vol.134 No.3
<P>This investigation is aimed at evaluating the epidemiologic characteristics of BRCA1/2 germline mutations in Korean patients with breast and ovarian cancer (BOC). We analyzed the entire mutational data of BRCA1/2 genes in BOC patients who were tested in Korea since the first Korean report of BRCA1 mutation in 1995 with the exception of the data covered in the Korean Hereditary Breast Cancer (KOHBRA) study, the project launched in 2007 for establishing BRCA1/2 carrier cohorts in Korea. In total, BRCA1/2 gene mutations of 3,922 Korean BOC patients were evaluated, including the unpublished data of 2,139 breast cancer patients examined by four Korean institutions and the data of 1,783 BOC patients covered in ten previous reports. Overall, 420 (150 distinct) pathogenic mutations were identified, 211 (73 distinct) in BRCA1 and 209 (77 distinct) in BRCA2. The majority (134 of 150) of the distinct mutations resulted in premature termination codon of the BRCA1/2 translation. BRCA1 c.4186-1593_4676-1465del was the only large genomic rearrangements mutation. Out of 150 distinct BRCA1/2 mutations, 84 (56 %) mutations were considered specific to Korean BOC. Eighty-five BRCA1/2 mutations were detected in at least two unrelated patients. These recurrent mutations account for 84.5 % (355 of 420) of mutations detected in the Korean population. In the pooled mutational data of BRCA1/2 genes, this study discovered the prevalence of BRCA1/2 mutations in the Korean BOC patients is similar to those found in other ethnic groups. Large genomic rearrangements in BRCA1/2 genes were infrequently detected among the Korean patients with BOC. There were several BRCA1/2 mutation candidates for founder mutations. To further establish a Korean cohort for BRCA1/2 mutations, the nationwide KOHBRA study is in progress.</P>
Choi, Ji Soo,Leem, Joong Woo,Lee, Kyung Hee,Kim, Sung-Soo,SuhKim, Haeyoung,Jung, Se Jung,Kim, Un Jeng,Lee, Bae Hwan The Korean Society of Pharmacology 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.6
The spontaneous axon regeneration of damaged neurons is limited after spinal cord injury (SCI). Recently, mesenchymal stem cell (MSC) transplantation was proposed as a potential approach for enhancing nerve regeneration that avoids the ethical issues associated with embryonic stem cell transplantation. As SCI is a complex pathological entity, the treatment of SCI requires a multipronged approach. The purpose of the present study was to investigate the functional recovery and therapeutic potential of human MSCs (hMSCs) and polymer in a spinal cord hemisection injury model. Rats were subjected to hemisection injuries and then divided into three groups. Two groups of rats underwent partial thoracic hemisection injury followed by implantation of either polymer only or polymer with hMSCs. Another hemisection-only group was used as a control. Behavioral, electrophysiological and immunohistochemical studies were performed on all rats. The functional recovery was significantly improved in the polymer with hMSC-transplanted group as compared with control at five weeks after transplantation. The results of electrophysiologic study demonstrated that the latency of somatosensory-evoked potentials (SSEPs) in the polymer with hMSC-transplanted group was significantly shorter than in the hemisection-only control group. In the results of immunohistochemical study, ${\beta}$-gal-positive cells were observed in the injured and adjacent sites after hMSC transplantation. Surviving hMSCs differentiated into various cell types such as neurons, astrocytes and oligodendrocytes. These data suggest that hMSC transplantation with polymer may play an important role in functional recovery and axonal regeneration after SCI, and may be a potential therapeutic strategy for SCI.