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1.  Phosphoacceptors Threonine 162 and Serines 170 and 178 within the Carboxyl-Terminal RRRS/T Motif of the Hepatitis B Virus Core Protein Make Multiple Contributions to Hepatitis B Virus Replication 
Journal of Virology  2014;88(16):8754-8767.
Phosphorylation of serines 157, 164, and 172 within the carboxyl-terminal SPRRR motif of the hepatitis B virus (HBV) core (C) protein modulates HBV replication at multiple stages. Threonine 162 and serines 170 and 178, located within the carboxyl-terminal conserved RRRS/T motif of HBV C protein, have been proposed to be protein kinase A phosphorylation sites. However, in vivo phosphorylation of these residues has never been observed, and their contribution to HBV replication remains unknown. In this study, [32P]orthophosphate labeling of cells expressing C proteins followed by immunoprecipitation with anti-HBc antibody revealed that threonine 162 and serines 170 and 178 are phosphoacceptor residues. A triple-alanine-substituted mutant, mimicking dephosphorylation of all three residues, drastically decreased pregenomic RNA (pgRNA) encapsidation, thereby decreasing HBV DNA synthesis. In contrast, a triple-glutamate-substituted mutant, mimicking phosphorylation of these residues, decreased DNA synthesis without significantly decreasing encapsidation. Neither triple mutant affected C protein expression or core particle assembly. Individual alanine substitution of threonine 162 significantly decreased minus-strand, plus-strand, and relaxed-circular DNA synthesis, demonstrating that this residue plays multiple roles in HBV DNA synthesis. Double-alanine substitution of serines 170 and 178 reduced HBV replication at multiple stages, indicating that these residues also contribute to HBV replication. Thus, in addition to serines 157, 164, and 172, threonine 162 and serines 170 and 178 of HBV C protein are also phosphorylated in cells, and phosphorylation and dephosphorylation of these residues play multiple roles in modulation of HBV replication.
IMPORTANCE Threonine 162, within the carboxyl-terminal end of the hepatitis B virus (HBV adw) core (C) protein, has long been ignored as a phosphoacceptor, even though it is highly conserved among mammalian hepadnaviruses and in the overlapping consensus RxxS/T, RRxS/T, and TP motifs. Here we show, for the first time, that in addition to the well-known phosphoacceptor serines 157, 164, and 172 in SPRRR motifs, threonine 162 and serines 170 and 178 in the RRRS/T motif are phosphorylated in cells. We also show that, like serines 157, 164, and 172, phosphorylated and dephosphorylated threonine 162 and serines 170 and 178 contribute to multiple steps of HBV replication, including pgRNA encapsidation, minus-strand and plus-strand DNA synthesis, and relaxed-circular DNA synthesis. Of these residues, threonine 162 is the most important. Furthermore, we show that phosphorylation of C protein is required for efficient completion of HBV replication.
PMCID: PMC4136252  PMID: 24850741
2.  Molecular Basis for SMC Rod Formation and Its Dissolution upon DNA Binding 
Molecular Cell  2015;57(2):290-303.
SMC condensin complexes are central modulators of chromosome superstructure in all branches of life. Their SMC subunits form a long intramolecular coiled coil, which connects a constitutive “hinge” dimerization domain with an ATP-regulated “head” dimerization module. Here, we address the structural arrangement of the long coiled coils in SMC complexes. We unequivocally show that prokaryotic Smc-ScpAB, eukaryotic condensin, and possibly also cohesin form rod-like structures, with their coiled coils being closely juxtaposed and accurately anchored to the hinge. Upon ATP-induced binding of DNA to the hinge, however, Smc switches to a more open configuration. Our data suggest that a long-distance structural transition is transmitted from the Smc head domains to regulate Smc-ScpAB’s association with DNA. These findings uncover a conserved architectural theme in SMC complexes, provide a mechanistic basis for Smc’s dynamic engagement with chromosomes, and offer a molecular explanation for defects in Cornelia de Lange syndrome.
Graphical Abstract
•Prokaryotic Smc-ScpAB complexes form rod-like structures•Binding of ATP and DNA induces a rod-to-ring transition in prokaryotic condensin•The condensin hinge is rigidly anchored to its coiled coil•The rod-like conformation is a conserved feature of SMC protein dimers
Soh et al. show that the rod-like conformation is a conserved architectural scheme of SMC complexes. Upon ATP-induced binding to DNA, the juxtaposed coiled coils of prokaryotic Smc-ScpAB adopt an open conformation to expose a DNA binding site at the inner surface of the hinge domain.
PMCID: PMC4306524  PMID: 25557547
3.  Oral toxicity of isotretinoin, misoprostol, methotrexate, mifepristone and levonorgestrel as pregnancy category X medications in female mice 
An oral toxicity study of several pregnancy category X drugs was performed in female ICR mice. The drugs were administered orally once daily for 3 days at doses of 1, 10 and 100 μg/kg for isotretinoin; 6.7, 67 and 670 μg/kg for misoprostol; 83, 830 and 8,300 μg/kg for methotrexate; 3.3, 33 and 330 μg/kg for mifepristone; and 25, 250 and 2,500 μg/kg for levonorgestrel. During the test period, clinical signs, mortality, body weight, hematology, serum biochemistry and necropsy findings were examined. Following administration of methotrexate at 8,300 μg/kg, a number of animals exhibited decreased spontaneous activity, and one animal died. In the hematological analysis, compared with those treated with the control, the animals treated with the drugs exhibited similar significant decreases in the number of granulocytes and granulocyte differentiation, and increases in lymphocyte differentiation. In the serum biochemical analysis, animals receiving high doses of the five drugs demonstrated significant changes in uric acid, glucose, alkaline phosphatase, total bilirubin, lipase, total cholesterol and calcium. At necropsy, intestinal redness was frequently observed in animals that received the high dose of methotrexate. Uterus enlargement and ovary dropsy were also detected in the groups receiving mifepristone and levonorgestrel. Despite the short-term exposure, these drugs exhibited significant side effects, including white blood cell toxicity, in the mouse model. Category X drugs can be traded illegally via the internet for the purpose of early pregnancy termination. Thus, illegal abuse of the drugs should be further discouraged to protect mothers.
PMCID: PMC4316989  PMID: 25667641
toxicity; pregnancy category X drugs; mice
4.  Incidence and Prognostic Impact of DNMT3A Mutations in Korean Normal Karyotype Acute Myeloid Leukemia Patients 
BioMed Research International  2015;2015:723682.
Background. DNA methyltransferase 3A (DNMT3A) mutation was recently introduced as a prognostic indicator in normal karyotype (NK) AML and we evaluated the incidence and prognostic impact of DNMT3A mutations in Korean NK AML patients. Methods. Total 67 NK AML patients diagnosed during the recent 10 years were enrolled. DNMT3A mutations were analyzed by direct sequencing and categorized into nonsynonymous variations (NSV), deleterious mutations (DM), and R882 mutation based on in silico analysis results. Clinical features and prognosis were compared with respect to DNMT3A mutation status. Results. Three novel (I158M, K219V, and E177V) and two known (R736H and R882H) NSVs were identified and the latter three were predicted as DMs. DNMT3A NSVs, DMs, and R882 mutation were identified in 14.9%–17.9%, 10.3%–10.4%, and 7.5% of patients, respectively. DNMT3A mutations were frequently detected in FLT3 ITD mutated patients (P = 0.054, 0.071, and 0.071 in NSV, DMs, and R882 mutation, resp.) but did not affect clinical features and prognosis significantly. Conclusions. Incidences of DNMT3A NSVs, DMs, and R882 mutation are 14.9%–17.9%, 10.3%–10.4%, and 7.5%, respectively, in Korean NK AML patients. DNMT3A mutations are associated with FLT3 ITD mutations but do not affect clinical outcome significantly in Korean NK AML patients.
PMCID: PMC4306257  PMID: 25650308
5.  Evaluation of cervical lymph node metastasis in thyroid cancer patients using real-time CT-navigated ultrasonography: preliminary study 
Ultrasonography  2014;34(1):39-44.
To evaluate the diagnostic accuracy of real-time neck computed tomography (CT)-guided ultrasonography (US) in detecting cervical neck lymph node metastasis (LNM) in patients with papillary thyroid cancer (PTC).
We retrospectively reviewed data from 176 patients (mean age, 43 years; range, 23 to 74 years) with surgically confirmed PTC who underwent preoperative US, neck CT, and neck CTguided US. We then compared the sensitivities and diagnostic accuracies of each of the three above modalities in detecting cervical LNM.
Preoperative US showed 17.3% sensitivity and 58.5% diagnostic accuracy in detecting central LNM compared with 64.3% sensitivity and 89.2% diagnostic accuracy in detecting lateral neck LNM. Neck CT showed 23.5% sensitivity and 55.7% diagnostic accuracy in detecting central LNM and 71.4% sensitivity with 90.9% diagnostic accuracy in detecting lateral neck LNM. CT-guided US exhibited 37.0% sensitivity and 63.1% diagnostic accuracy in detecting central LNM compared with 92.9% sensitivity and 96.0% diagnostic accuracy in detecting lateral LNM. CT-guided US showed higher diagnostic accuracy with superior sensitivity in detecting central and lateral LNM than did US (P<0.001, P=0.011) and CT (P=0.026, P=0.063).
Neck CT-guided US is a more accurate technique with higher sensitivity for detecting cervical LNM than either US or CT alone. Therefore, our data indicate that neck CT-guided US is an especially useful technique in preoperative examinations.
PMCID: PMC4282224  PMID: 25327528
Thyroid cancer, papillary; Lymph nodes; Neoplasm metastasis; Ultrasonography; Multidetector computed tomography
6.  Effect of zinc oxide nanoparticles on dams and embryo–fetal development in rats 
International Journal of Nanomedicine  2014;9(Suppl 2):145-157.
This study investigated the potential adverse effects of zinc oxide nanoparticles (ZnOSM20[−] NPs; negatively charged, 20 nm) on pregnant dams and embryo–fetal development after maternal exposure over the period of gestational days 5–19 with Sprague Dawley rats. ZnOSM20(−) NPs were administered to pregnant rats by gavage at 0 mg/kg/day, 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day. All dams were subjected to caesarean section on gestational day 20, and all the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight at 400 mg/kg/day and decreased liver weight, and increased adrenal glands weight at 200 mg/kg/day and 400 mg/kg/day. However, no treatment-related difference in the number of corpora lutea, the number of implantation sites, the implantation rate (%), resorption, dead fetuses, litter size, fetal deaths, fetal and placental weights, and sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in the incidences of abnormalities between the groups. No significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that a 15-day repeated oral dose of ZnOSM20(−) was minimally maternotoxic at dose of 200 mg/kg/day and 400 mg/kg/day.
PMCID: PMC4279755  PMID: 25565833
nanotoxicology; nanoparticles; zinc oxide; maternal toxicity; developmental toxicity; teratogenicity
7.  Prenatal development toxicity study of zinc oxide nanoparticles in rats 
International Journal of Nanomedicine  2014;9(Suppl 2):159-171.
This study investigated the potential adverse effects of zinc oxide nanoparticles ([ZnOSM20(+) NPs] zinc oxide nanoparticles, positively charged, 20 nm) on pregnant dams and embryo–fetal development after maternal exposure over the period of gestational days 5–19 with Sprague-Dawley rats. ZnOSM20(+) NPs were administered to pregnant rats by gavage at 0, 100, 200, and 400 mg/kg/day. All dams were subjected to a cesarean section on gestational day 20, and all of the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight after administration of 400 mg/kg/day NPs; reduced food consumption after administration of 200 and 400 mg/kg/day NPs; and decreased liver weight and increased adrenal glands weight after administration of 400 mg/kg/day NPs. However, no treatment-related difference in: number of corpora lutea; number of implantation sites; implantation rate (%); resorption; dead fetuses; litter size; fetal deaths and placental weights; and sex ratio were observed between the groups. On the other hand, significant decreases between treatment groups and controls were seen for fetal weights after administration of 400 mg/kg/day NPs. Morphological examinations of the fetuses demonstrated significant differences in incidences of abnormalities in the group administered 400mg/kg/day. Meanwhile, no significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that oral doses for the study with 15-days repeated of ZnOSM20(+) NPs were maternotoxic in the 200 mg/kg/day group, and embryotoxic in the 400 mg/kg/day group.
PMCID: PMC4279776  PMID: 25565834
developmental toxicity; maternal toxicity; nanotoxicology; teratogenicity
8.  Monosomal and complex karyotypes as prognostic parameters in patients with International Prognostic Scoring System higher risk myelodysplastic syndrome treated with azacitidine 
Blood research  2014;49(4):234-240.
Azacitidine (AZA) is standard care for patients with myelodysplastic syndrome (MDS) who have not had allogeneic stem cell transplantation. Chromosomal abnormalities (CA) including complex karyotype (CK) or monosomal karyotype (MK) are associated with clinical outcome in patients with MDS.
We investigated which prognostic factors including CAs would predict clinical outcomes in patients with International Prognostic Scoring System (IPSS) higher risk MDS treated with AZA, retrospectively. CK was defined as the presence of three or more numerical or structural CAs. MK was defined as the presence of two or more distinct autosomal monosomies or single autosomal monosomy with at least one additional structural CA.
A total of 243 patients who treated with AZA, were enrolled. CK was present in 124 patients and MK was present in 90 patients. Bone marrow blasts ≥15% and CK were associated with poorer response (P=0.038, P=0.007) and overall survival (OS) (P<0.001, P<0.001) independently. Although MK in CK group was not associated with prognosis, non-MK status in non-CK group reflected favorable OS (P=0.005). The group including >3 CAs was associated with poorer OS (group including <3 CAs vs. only three CAs, P=0.001; group with >3 CAs vs. only three CAs, P=0.001).
CK was an important prognostic parameter associated with worse outcome. MK may predict poor survival in only non-CK status. The higher number of CAs was associated with poorer survival.
PMCID: PMC4278004  PMID: 25548756
Myelodysplastic syndrome; Azacitidine; Complex karyotype; Monosomal karyotype; Chromosomal abnormalities
9.  Clinical significance of nuclear factor κB and chemokine receptor CXCR4 expression in patients with diffuse large B-cell lymphoma who received rituximab-based therapy 
This study investigated the expression of nuclear factor κB (NF-κB) and the chemokine receptor (CXCR4) in patients with diffuse large B-cell lymphoma (DLBCL) who received rituximab-based therapy.
Seventy patients with DLBCL and treated with rituximab-CHOP (R-CHOP) were included, and immunohistochemistry was performed to determine the expression of NF-κB (IκB kinase α, p50, and p100/p52) and CXCR4. To classify DLBCL cases as germinal center B-cell-like (GCB) and non-GCB, additional immunohistochemical expression of CD10, bcl-6, or MUM1 was used in this study. The expression was divided into two groups according to the intensity score (negative, 0 or 1+; positive, 2+ or 3+).
The median age of the patients was 66 years (range, 17 to 87), and 58.6% were male. Twenty-seven patients (38.6%) had stage III or IV disease at diagnosis. Twenty-three patients (32.9%) were categorized as high or high-intermediate risk according to their International Prognostic Indexs (IPIs). The overall incidence of bone marrow involvement was 5.7%. Rates of positive NF-κB and CXCR4 expression were 84.2% and 88.6%, respectively. High NF-κB expression was associated with CXCR4 expression (p = 0.002), and 56 patients (80.0%) showed coexpression. However, the expression of NF-κB or CXCR4 was not associated with overall survival and EFS. On multivariate analysis that included age, gender, performance status, stage, and the IPI, no significant association between the grade of NF-κB or CXCR4 expression and survival was observed.
The current study suggests that the tissue expression of NF-κB and CXCR4 may not be an independent prognostic marker in DLBCL patients treated with R-CHOP.
PMCID: PMC4219968  PMID: 25378977
Lymphoma; NF-kappa B; CXCR4
10.  Ginseng Gintonin Activates the Human Cardiac Delayed Rectifier K+ Channel: Involvement of Ca2+/Calmodulin Binding Sites 
Molecules and Cells  2014;37(9):656-663.
Gintonin, a novel, ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand, elicits [Ca2+]i transients in neuronal and non-neuronal cells via pertussis toxin-sensitive and pertussis toxin-insensitive G proteins. The slowly activating delayed rectifier K+ (IKs) channel is a cardiac K+ channel composed of KCNQ1 and KCNE1 subunits. The C terminus of the KCNQ1 channel protein has two calmodulin-binding sites that are involved in regulating IKs channels. In this study, we investigated the molecular mechanisms of gintonin-mediated activation of human IKs channel activity by expressing human IKs channels in Xenopus oocytes. We found that gintonin enhances IKs channel currents in concentration- and voltage-dependent manners. The EC50 for the IKs channel was 0.05 ± 0.01 μg/ml. Gintonin-mediated activation of the IKs channels was blocked by an LPA1/3 receptor antagonist, an active phospholipase C inhibitor, an IP3 receptor antagonist, and the calcium chelator BAPTA. Gintonin-mediated activation of both the IKs channel was also blocked by the calmodulin (CaM) blocker calmidazolium. Mutations in the KCNQ1 [Ca2+]i/CaM-binding IQ motif sites (S373P, W392R, or R539W)blocked the action of gintonin on IKs channel. However, gintonin had no effect on hERG K+ channel activity. These results show that gintonin-mediated enhancement of IKs channel currents is achieved through binding of the [Ca2+]i/CaM complex to the C terminus of KCNQ1 subunit.
PMCID: PMC4179134  PMID: 25234465
ginseng; gintonin; heart; IKs channel; LPA receptor
11.  Evaluating the Utility of Rapid Point-of-Care Potassium Testing for the Early Identification of Hyperkalemia in Patients with Chronic Kidney Disease in the Emergency Department 
Yonsei Medical Journal  2014;55(5):1348-1353.
Severe hyperkalemia leads to significant morbidity and mortality if it is not immediately recognized and treated. The concentration of potassium (K+) in the serum increases along with deteriorating renal function. The use of point-of-care K+ (POC-K+) in chronic kidney disease (CKD) could reduce the time for an accurate diagnosis and treatment, saving lives. We hypothesized that POC-K+ would accurately report K+ serum level without significant differences compared to reference testing, regardless of the renal function of the patient.
Materials and Methods
The retrospective study was performed between January 2008 and September 2011 at an urban hospital in Seoul. The screening program using POC was conducted as a critical pathway for rapid evaluation and treatment of hyperkalemia since 2008. When a patient with CKD had at least one warning symptom or sign of hyperkalemia, both POC-K+ and routine laboratory tests were simultaneously ordered. The reliability of the two assays for serum-creatinine was assessed by intra-class correlation coefficient (ICC) analysis using absolute agreement of two-way mixed model.
High levels of reliability were found between POC and the laboratory reference tests for K+ (ICC=0.913, 95% CI 0.903-0.922) and between two tests for K+ according to changes in the serum-creatinine levels in CKD patients.
The results of POC-K+ correlate well with values obtained from reference laboratory tests and coincide with changes in serum-creatinine of patients with CKD.
PMCID: PMC4108822  PMID: 25048495
Point-of-care testing; hyperkalemia; chronic kidney disease
12.  Influence of NK cell count on the survival of patients with diffuse large B-cell lymphoma treated with R-CHOP 
Blood research  2014;49(3):162-169.
Although adding rituximab to the chemotherapy regimen of cyclophosphamide, vincristine, doxorubicin, and prednisone (R-CHOP) has improved clinical outcomes of patients with diffuse large B-cell lymphoma (DLBCL), several recent studies have shown that the effect of rituximab is dominantly in the non-germinal center (non-GC) subtype compared to the germinal center (GC) subtype. Natural killer (NK) cell count, a surrogate marker of immune status, is associated with clinical outcomes in DLBCL patients in the rituximab era. We investigated whether the impact of NK cells on clinical outcomes differed according to the immunophenotype of DLBCL.
This study analyzed 72 DLBCL patients treated with R-CHOP between January 2010 and January 2014.
Low NK cell counts (<100/µL) were associated with poor progression-free survival (PFS) and overall survival (OS) compared to high NK cell counts. In multivariate analysis, low NK cell count was an independent prognostic factor for PFS and OS. However, survival did not significantly differ between the GC and non-GC subtypes. We examined the clinical influence of NK cells according to the immunophenotype and found that low NK cell counts were significantly associated with poor PFS and OS in non-GC cases, but not in GC cases.
Low NK cell counts at diagnosis are associated with poor clinical outcomes in DLBCL patients treated with R-CHOP therapy. However, the impact is significant only in non-GC subtype DLBCL, not in the GC subtype.
PMCID: PMC4188781  PMID: 25325035
Natural killer cell coun; Diffuse large B-cell lymphoma; Rituximab; Germinal center type; Non-germinal center type
13.  Anesthetic management of transoral natural orifice transluminal endoscopic surgery: two cases report 
Korean Journal of Anesthesiology  2014;67(2):148-152.
Natural orifice transluminal endoscopic surgery (NOTES) is an evolving field of minimally invasive surgery. NOTES reaches the target organ by inserting the endoscope through a natural orifice (e.g. mouth, anus, urethra, vagina) and offers advantages of less postoperative pain and lower complication rate. Since its first description in 2004, NOTES has progressed from use on animal models to humans. We experienced anesthetic care of two patients who underwent transoral NOTES under general anesthesia.
PMCID: PMC4166389  PMID: 25237454
Anesthesia; Natural orifice transluminal endoscopic surgery
14.  Binding of fullerenes and nanotubes to MscL 
Scientific Reports  2014;4:5609.
Multi-drug resistance is becoming an increasing problem in the treatment of bacterial infections and diseases. The mechanosensitive channel of large conductance (MscL) is highly conserved among prokaryotes. Evidence suggests that a pharmacological agent that can affect the gating of, or block the current through, MscL has significant potential as a new class of antimicrobial compound capable of targeting a range of pathogenic bacteria with minimal side-effects to infected patients. Using molecular dynamics we examine the binding of fullerenes and nanotubes to MscL and demonstrate that both are stable within the MscL pore. We predict that fullerenes will attenuate the flow of ions through MscL by reducing the pore volume available to water and ions, but nanotubes will prevent pore closure resulting in a permanently open pore. Moreover, we confirm experimentally that it is possible to attenuate the flow of ions through MscL using a C60-γ cyclodextrin complex.
PMCID: PMC4101527  PMID: 25030051
15.  Performance of coumarin-derived dendrimer-based fluorescence-linked immunosorbent assay (FLISA) to detect malaria antigen 
Malaria Journal  2014;13:266.
Due to limitation of conventional malaria diagnostics, including microscopy, polymerase chain reaction (PCR), and enzyme-linked immunosorbent assay (ELISA), alternative accurate diagnostics have been demanded for improvement of sensitivity and specificity.
Serially diluted Plasmodium LDH antigens, Plasmodium falciparum-infected human red blood cells (RBC) derived from in vitro culture or patient’s samples were used for evaluation of the performance of fluorescence-linked immunosorbent assay (FLISA). Microscopic examination was used to determine parasite density and the performance of FLISA was compared to ELISA. Finally, sensitivity and specificity of FLISA was determined by human specimens infected with P. falciparum, Plasmodium vivax, Toxoplasma gondii, and amoebae.
As a result of FLISA, the fluorescent intensity was highly correlated with antigen amount and FLISA was more sensitive than ELISA. FLISA detected at least 0.01 ng/ml of pLDH antigen, which showed 1,000-fold higher sensitivity than ELISA. In vitro-cultured P. falciparum was detected up to 20 parasite number/μL in FLISA but 5120 parasite number/μLin sandwich ELISA. In vitro P. falciparum-infected RBC number was highly correlated with fluorescent intensity (R2 = 0.979), showing that FLISA was reliable for detection of P. falciparum and available for quantification of parasite numbers. Furthermore, eighteen patient samples infected with P. falciparum (n = 9) and P. vivax (n = 9) showed 100% of sensitivity (18/18). FLISA showed 96.3% of specificity (26/27) because one sample of patient blood infected with T. gondii gave a false positive reactivity among healthy donors (n = 9), T. gondii-infected patients (n = 9), and amoeba-infected patients (n = 9).
FLISA has a keen and high performance to detect malaria antigen, suggesting a potential assay as malaria immunodiagnostic.
PMCID: PMC4105783  PMID: 25011624
Coumarin-derived dendrimer; Fluorescence-linked immunosorbent assay (FLISA); Lactate dehydrogenase (LDH); ELISA; Plasmodium falciparum; Plasmodium vivax
16.  Clinical Significance of Non-Alcoholic Fatty Liver Disease as a Risk Factor for Prehypertension 
Journal of Korean Medical Science  2014;29(7):973-979.
Previous epidemiologic studies have shown the clinical association between non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD). However, there is only limited information about the effect of NAFLD on the development of hypertension. Accordingly, we investigated the clinical association between NAFLD and prehypertension. A prospective cohort study was conducted on the 11,350 Korean men without prehypertension for 5 yr. The incidences of prehypertension were evaluated, and Cox proportional hazard model was used to measure the hazard ratios (HRs) for the development of prehypertension according to the degree of NAFLD (normal, mild, moderate to severe). The incidence of prehypertension increased according to NAFLD states (normal: 55.5%, mild: 63.7%, moderate to severe: 70.3%, P<0.001). Even after adjusting for multiple covariates, the HRs (95% confidence interval) for prehypertension were higher in the mild group (1.18; 1.07-1.31) and moderate to severe group (1.62; 1.21-2.17), compared to normal group, respectively (P for trend <0.001). The development of prehypertension is more potentially associated with the more progressive NAFLD than normal and milder state. These findings suggest the clinical significance of NAFLD as one of risk factors for prehypertension.
PMCID: PMC4101786  PMID: 25045230
Non-Alcoholic Fatty Liver Disease; Blood Pressure; Prehypertension
17.  Binding Modes of Two Scorpion Toxins to the Voltage-Gated Potassium Channel Kv1.3 Revealed from Molecular Dynamics 
Toxins  2014;6(7):2149-2161.
Molecular dynamics (MD) simulations are used to examine the binding modes of two scorpion toxins, margatoxin (MgTx) and hongotoxin (HgTx), to the voltage gated K+ channel, Kv1.3. Using steered MD simulations, we insert either Lys28 or Lys35 of the toxins into the selectivity filter of the channel. The MgTx-Kv1.3 complex is stable when the side chain of Lys35 from the toxin occludes the channel filter, suggesting that Lys35 is the pore-blocking residue for Kv1.3. In this complex, Lys28 of the toxin forms one additional salt bridge with Asp449 just outside the filter of the channel. On the other hand, HgTx forms a stable complex with Kv1.3 when the side chain of Lys28 but not Lys35 protrudes into the filter of the channel. A survey of all the possible favorable binding modes of HgTx-Kv1.3 is carried out by rotating the toxin at 3° intervals around the channel axis while the position of HgTx-Lys28 relative to the filter is maintained. We identify two possible favorable binding modes: HgTx-Arg24 can interact with either Asp433 or Glu420 on the vestibular wall of the channel. The dissociation constants calculated from the two binding modes of HgTx-Kv1.3 differ by approximately 20 fold, suggesting that the two modes are of similar energetics.
PMCID: PMC4113748  PMID: 25054783
margatoxin; hongotoxin; Kv1.3; molecular dynamics; scorpion toxins
18.  Clinical Factors Associated with Response or Survival after Chemotherapy in Patients with Waldenström Macroglobulinemia in Korea 
BioMed Research International  2014;2014:253243.
Waldenström's macroglobulinemia (WM) is a B-cell proliferative malignancy characterized by immunoglobulin M monoclonal gammopathy and bone marrow infiltration by lymphoplasmacytic cells. Clinical features and cytogenetics of WM in Asia including Republic of Korea remain unclear. Moreover, no study has reported treatment outcomes in patients with WM treated with novel agent combined with conventional chemotherapy. This study investigated clinical features and assessed treatment outcomes with novel agent and conventional chemotherapy in Republic of Korea. Data from all (n = 71) patients with newly diagnosed WM at 17 hospitals who received chemotherapy between January 2005 and December 2012 were collected retrospectively. The median age of patients was 66 years (range: 37–92 years) and male to female ratio was 5 : 1. Patients treated with novel agent combined chemotherapy displayed higher overall response rate (ORR) compared to conventional chemotherapy alone (92.9% versus 52.6%, P = 0.006). The 5-year overall survival rate was 62.6% (95% confidence interval: 34.73–111.07). Use of novel agents produced higher ORR but survival benefit was not apparent due to the small number of patients and short follow-up duration. Further studies are needed to confirm the efficacy of novel agents in patients with WM.
PMCID: PMC4065725  PMID: 24995279
19.  Clinical characteristics, pathological distribution, and prognostic factors in non-Hodgkin lymphoma of Waldeyer's ring: nationwide Korean study 
In Asia, the incidence of non-Hodgkin lymphoma (NHL) has increased in recent decades. Waldeyer's ring (WR) is the most common site of NHL involving the head and neck. In this study, the pathological distribution of WR-NHL and its clinical features were analyzed retrospectively.
From January 2000 through December 2010, we analyzed the medical records of 328 patients from nine Korean institutions who were diagnosed with WR-NHL.
The study group comprised 197 male and 131 female patients with a median age of 58 years (range, 14 to 89). The rate of localized disease (stage I/II) was 64.9%, and that of low-risk disease (low/low-intermediate, as defined by the International Prognostic Index) was 76.8%. Diffuse large B-cell lymphoma (DLBCL; 240 patients, 73.2%) was the most common pathologic subtype, followed by peripheral T-cell lymphoma (14 patients, 4.3%) and nasal NK/T-cell lymphoma (14 patients, 4.3%). WR-NHL occurred most frequently in the tonsils (199 patients, 60.6%). Extranodal involvement was greater with the T-cell subtype (20 patients, 42.5%) compared with the B-cell subtype (69 patients, 24.5%). Multivariate analyses showed that age ≥ 62 years, T-cell subtype, and failure to achieve complete remission were significant risk factors for overall survival.
DLBCL was found to have a higher incidence in Korea than those incidences reported by other WR-NHL studies. T-cell lymphoma occurred more frequently than did follicular lymphoma. T-cell subtype, age ≥ 62 years, and complete remission failure after first-line treatment were significant poor prognostic factors for overall survival according to the multivariate analysis.
PMCID: PMC4028525  PMID: 24851070
Head and neck; Non-Hodgkin lymphoma; Diffuse large B-cell lymphoma; T-cell lymphoma
20.  Mechanism of μ-Conotoxin PIIIA Binding to the Voltage-Gated Na+ Channel NaV1.4 
PLoS ONE  2014;9(3):e93267.
Several subtypes of voltage-gated Na+ (NaV) channels are important targets for pain management. μ-Conotoxins isolated from venoms of cone snails are potent and specific blockers of different NaV channel isoforms. The inhibitory effect of μ-conotoxins on NaV channels has been examined extensively, but the mechanism of toxin specificity has not been understood in detail. Here the known structure of μ-conotoxin PIIIA and a model of the skeletal muscle channel NaV1.4 are used to elucidate elements that contribute to the structural basis of μ-conotoxin binding and specificity. The model of NaV1.4 is constructed based on the crystal structure of the bacterial NaV channel, NaVAb. Six different binding modes, in which the side chain of each of the basic residues carried by the toxin protrudes into the selectivity filter of NaV1.4, are examined in atomic detail using molecular dynamics simulations with explicit solvent. The dissociation constants (Kd) computed for two selected binding modes in which Lys9 or Arg14 from the toxin protrudes into the filter of the channel are within 2 fold; both values in close proximity to those determined from dose response data for the block of NaV currents. To explore the mechanism of PIIIA specificity, a double mutant of NaV1.4 mimicking NaV channels resistant to μ-conotoxins and tetrodotoxin is constructed and the binding of PIIIA to this mutant channel examined. The double mutation causes the affinity of PIIIA to reduce by two orders of magnitude.
PMCID: PMC3968119  PMID: 24676211
22.  Vaccination with Lentiviral Vector Expressing the nfa1 Gene Confers a Protective Immune Response to Mice Infected with Naegleria fowleri 
Naegleria fowleri, a pathogenic free-living amoeba, causes fatal primary amoebic meningoencephalitis (PAM) in humans and animals. The nfa1 gene (360 bp), cloned from a cDNA library of N. fowleri, produces a 13.1-kDa recombinant protein which is located on pseudopodia, particularly the food cup structure. The nfa1 gene plays an important role in the pathogenesis of N. fowleri infection. To examine the effect of nfa1 DNA vaccination against N. fowleri infection, we constructed a lentiviral vector (pCDH) expressing the nfa1 gene. For the in vivo mouse study, BALB/c mice were intranasally vaccinated with viral particles of a viral vector expressing the nfa1 gene. To evaluate the effect of vaccination and immune responses of mice, we analyzed the IgG levels (IgG, IgG1, and IgG2a), cytokine induction (interleukin-4 [IL-4] and gamma interferon [IFN-γ]), and survival rates of mice that developed PAM. The levels of both IgG and IgG subclasses (IgG1 and IgG2a) in vaccinated mice were significantly increased. The cytokine analysis showed that vaccinated mice exhibited greater IL-4 and IFN-γ production than the other control groups, suggesting a Th1/Th2 mixed-type immune response. In vaccinated mice, high levels of Nfa1-specific IgG antibodies continued until 12 weeks postvaccination. The mice vaccinated with viral vector expressing the nfa1 gene also exhibited significantly higher survival rates (90%) after challenge with N. fowleri trophozoites. Finally, the nfa1 vaccination effectively induced protective immunity by humoral and cellular immune responses in N. fowleri-infected mice. These results suggest that DNA vaccination using a viral vector may be a potential tool against N. fowleri infection.
PMCID: PMC3697439  PMID: 23677321
23.  Clinical Outcomes and Prognostic Factors of Empirical Antifungal Therapy with Itraconazole in the Patients with Hematological Malignancies: A Prospective Multicenter Observational Study in Korea 
Yonsei Medical Journal  2013;55(1):9-18.
To identify prognostic factors for the outcomes of empirical antifungal therapy, we performed a multicenter, prospective, observational study in immunocompromised patients with hematological malignancies.
Materials and Methods
Three hundred seventy-six patients (median age of 48) who had neutropenic fever and who received intravenous (IV) itraconazole as an empirical antifungal therapy for 3 or more days were analyzed. The patients with possible or probable categories of invasive fungal disease (IFD) were enrolled.
The overall success rate was 51.3% (196/376). Age >50 years, underlying lung disease (co-morbidity), poor performance status [Eastern Cooperative Oncology Group (ECOG) ≥2], radiologic evidence of IFD, longer duration of baseline neutropenic fever (≥4 days), no antifungal prophylaxis or prophylactic use of antifungal agents other than itraconazole, and high tumor burden were associated with decreased success rate in univariate analysis. In multivariate analysis, age >50 years (p=0.009) and poor ECOG performance status (p=0.005) were significantly associated with poor outcomes of empirical antifungal therapy. Twenty-two patients (5.9%) discontinued itraconazole therapy due to toxicity.
We concluded that empirical antifungal therapy with IV itraconazole in immunocompromised patients is effective and safe. Additionally, age over 50 years and poor performance status were poor prognostic factors for the outcomes of empirical antifungal therapy with IV itraconazole.
PMCID: PMC3874917  PMID: 24339281
Hematological malignancy; prognosis; itraconazole; empirical antifungal therapy
24.  Spinal Noradrenergic Modulation and the Role of the Alpha-2 Receptor in the Antinociceptive Effect of Intrathecal Nefopam in the Formalin Test 
The Korean Journal of Pain  2013;27(1):23-29.
Nefopam has shown an analgesic effect on acute pain including postoperative pain. The reuptake of monoamines including serotonin and noradrenaline has been proposed as the mechanism of the analgesic action of nefopam, but it remains unclear. Although alpha-adrenergic agents are being widely used in the perioperative period, the role of noradrenergic modulation in the analgesic effect of nefopam has not been fully addressed.
Changes in the antinociceptive effect of intrathecal (i.t.) nefopam against formalin-elicited flinching responses were explored in Sprague-Dawley rats pretreated with i.t. 6-hydroxydopamine (6-OHDA), which depletes spinal noradrenaline. In addition, antagonism to the effect of nefopam by prazosin and yohimbine was evaluated to further elucidate the antinociceptive mechanism of i.t. nefopam.
Pretreatment with i.t. 6-OHDA alone did not alter the flinching responses in either phase of the formalin test, while it attenuated the antinociceptive effect of i.t. nefopam significantly during phase 1, but not phase 2. The antagonist of the alpha-2 receptor, but not the alpha-1 receptor, reduced partially, but significantly, the antinociceptive effect of i.t. nefopam during phase 1, but not during phase 2.
This study demonstrates that spinal noradrenergic modulation plays an important role in the antinociceptive effect of i.t. nefopam against formalin-elicited acute initial pain, but not facilitated pain, and this action involves the spinal alpha-2 but not the alpha-1 receptor.
PMCID: PMC3903796  PMID: 24478897
alpha-2 receptor; formalin; nefopam; noradrenergic system; spinal cord
25.  Practice guideline for the performance of breast ultrasound elastography 
Ultrasonography  2013;33(1):3-10.
Ultrasound (US) elastography is a valuable imaging technique for tissue characterization. Two main types of elastography, strain and shear-wave, are commonly used to image breast tissue. The use of elastography is expected to increase, particularly with the increased use of US for breast screening. Recently, the US elastographic features of breast masses have been incorporated into the 2nd edition of the Breast Imaging Reporting and Data System (BI-RADS) US lexicon as associated findings. This review suggests practical guidelines for breast US elastography in consensus with the Korean Breast Elastography Study Group, which was formed in August 2013 to perform a multicenter prospective study on the use of elastography for US breast screening. This article is focused on the role of elastography in combination with B-mode US for the evaluation of breast masses. Practical tips for adequate data acquisition and the interpretation of elastography results are also presented.
PMCID: PMC4058975  PMID: 24936489
Breast, neoplasms; Ultrasonography; Elasticity imaging techniques

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