Effect of self-learning media based on 360° virtual reality for learning periodontal instrument skills.

INTRODUCTION: Of 360° Virtual Reality (VR) is possibly produced and sufficiently effective as a consumer-friendly VR learning medium. Therefore, it is also expected to be useful in the dental practice field, as a self-learning medium for non-face-to-face skill training during the ongoing pandemic (COVID-19). Accordingly, this study was conducted to assess 360° VR self-learning media for a periodontal instrument operation. MATERIALS AND METHODS: We recruited 30 participants who had never experienced instrument training. We offered basic education and initial assessment (IA), then divided them into three groups: 1) PAPER: trained only with paper handouts; 2) 2D: trained with 2D video; 3) VR: trained with 360° VR. Each group performed self-learning and mid-term assessment (MA). Subjects then implemented home self-learning with the same media for one week, which was then followed by a final assessment (FA). RESULT: Analysis of IA-to-FA improvement scores showed that VR and 2D video were significantly higher than the PAPER groups. Meanwhile, analysis of MA-to-FA improvement scores showed that only VR was substantially higher than the PAPER group. Although VR and 2D video groups were not considerably different, VR scores were numerically higher than 2D video in all improvement score analyses. DISCUSSION: Both 2D video and 360° VR training were helpful to participants for an effective self-learning and also had good portability and accessibility as online-based learning methods. 360° VR showed higher learning efficiency than regular 2D video, possibly due to its autonomy, 360° visual information and physical and immersive characteristics, which positively affected self-training. CONCLUSION: Our findings showed the potential of 360° VR learning media and, further, suggest its usefulness as a novel self-learning method in future dental education.

Socioeconomic status, food security, and chewing discomfort of Korean elders: results from the Korea National Health and Nutrition Examination Survey.

BACKGROUND/OBJECTIVES: The purpose of this study was to investigate the association between socioeconomic status and chewing discomfort and identify the role of food insecurity in the association's causal pathway in a representative sample of Korean elders. MATERIALS/METHODS: We conducted cross-sectional analyses of the Korea National Health and Nutrition Examination Survey (2013-2015) data for elders aged ≥ 65 years. Socioeconomic status indicators used included household income and education level. Chewing discomfort was assessed according to the self-reported presence of chewing problems. Food security was surveyed using a questionnaire based on the US Household Food Security Survey Module. RESULTS: The odds ratios of chewing discomfort in the 1st and 2nd income quartiles were 1.55 (95% confidence interval [CI], 1.15-2.10) and 1.40 (95% CI, 1.03-1.90), respectively, compared to participants in the highest income quartile. Participants with the lowest education level were 1.89 (95% CI, 1.30-2.75) times more likely to have chewing discomfort than those without chewing discomfort. After including food security in the final model, the logistic coefficients were attenuated in the income and education quartiles. CONCLUSIONS: Low socioeconomic status was associated with chewing discomfort. In addition, the results confirm that food insecurity can mediate the association between socioeconomic inequalities and chewing discomfort among the elderly.

Nox4-IGF2 Axis Promotes Differentiation of Embryoid Body Cells Into Derivatives of the Three Embryonic Germ Layers.

Reactive oxygen species (ROS) play important roles as second messengers in a wide array of cellular processes including differentiation of stem cells. We identified Nox4 as the major ROS-generating enzyme whose expression is induced during differentiation of embryoid body (EB) into cells of all three germ layers. The role of Nox4 was examined using induced pluripotent stem cells (iPSCs) generated from Nox4 knockout (Nox4-/-) mouse. Differentiation markers showed significantly reduced expression levels consistent with the importance of Nox4-generated ROS during this process. From transcriptomic analyses, we found insulin-like growth factor 2 (IGF2), a member of a gene family extensively involved in embryonic development, as one of the most down-regulated genes in Nox4-/- cells. Indeed, addition of IGF2 to culture partly restored the differentiation competence of Nox4-/- iPSCs. Our results reveal an important signaling axis mediated by ROS in control of crucial events during differentiation of pluripotent stem cells.

Clinical risk factors and pattern of initial fungal contamination in endoscopic biopsy-derived gastrointestinal cancer organoid culture.

BACKGROUND/AIMS: Because gastrointestinal tract is not sterile, primary culture has contamination risk despite of massive washing with antimicrobial media. Microbial contamination can play a key role in initial failure during biopsy-derived primary tumor culture. METHODS: Tumor tissue was acquired from esophageal and gastric tumors using endoscopic biopsy. Three-dimensional cultures were performed, and separated spheroids were cultured in media for 7 to 10 days and then transferred to Matrigel (Corning Inc.). We investigated risk factors and patterns of initial fungal contamination. RESULTS: Initial tumor contamination was observed in 23% (7/30) of esophageal cancer and 20% (3/15) of gastric cancer samples. Two cases of bacterial contamination occurred during the establishment of culture protocol. Moderate to thick whitish plaques (p < 0.001) and food retention in lumen (p < 0.001) were risk factors for initial fungal contamination. After exclusion of high risk patients for contamination, no fungal contamination occurred in primary organoid cultures. Fungal contamination was usually detected within 3 days after tumor preparation. However, unusual fungal contamination (GC11 and EC29) was recognized after several passages. Growing spherical shapes resembled cancer organoids. Although they rapidly proliferated and multiple daughter spheroids appeared, the media were translucent. After several passages, yeasts and pseudohyphae were detected on the edges of the solid spherical structures and media. CONCLUSION: Moderate to thick whitish plaques and food retention are clinical risk factors for initial fungal contamination during biopsy-derived cancer organoid culture. Most initial fungal contamination was detected within 3 days, but it could be unusually recognized after several passages.

Ahnak deficiency attenuates high-fat diet-induced fatty liver in mice through FGF21 induction.

The AHNAK nucleoprotein has been determined to exert an anti-obesity effect in adipose tissue and further inhibit adipogenic differentiation. In this study, we examined the role of AHNAK in regulating hepatic lipid metabolism to prevent diet-induced fatty liver. Ahnak KO mice have reportedly exhibited reduced fat accumulation in the liver and decreased serum triglyceride (TG) levels when provided with either a normal chow diet or a high-fat diet (HFD). Gene expression profiling was used to identify novel factors that could be modulated by genetic manipulation of the Ahnak gene. The results revealed that fibroblast growth factor 21 (FGF21) was markedly increased in the livers of Ahnak KO mice compared with WT mice fed a HFD. Ahnak knockdown in hepatocytes reportedly prevented excessive lipid accumulation induced by palmitate treatment and was associated with increased secretion of FGF21 and the expression of genes involved in fatty acid oxidation, which are primarily downstream of PPARα. These results indicate that pronounced obesity and hepatic steatosis are attenuated in HFD-fed Ahnak KO mice. This may be attributed, in part, to the induction of FGF21 and regulation of lipid metabolism, which are considered to be involved in increased fatty acid oxidation and reduced lipogenesis in the liver. These findings suggest that targeting AHNAK may have beneficial implications in preventing or treating hepatic steatosis.

The association between oral health literacy and oral health behaviors in North Korean defectors: a cross-sectional study.

BACKGROUND: The present study aimed to investigate the association between oral health literacy and oral health behaviors among North Korean defectors. METHODS: This study involved the collection of self-reported questionnaires from 123 North Korean defectors visited a dental clinic that offered complimentary services, to receive dental treatment in a metropolitan area of South Korea from December 2017 to April 2018. Oral health literacy was measured with the Test of Korean Functional Health Literacy in Dentistry (TOKFHLiD), which consists of 30 items concerning verbal oral health literacy and 42 items concerning functional oral health literacy (28 items for reading comprehension and 14 items for numeracy). In addition, the questionnaire contains 15 and 14 items related to demographic characteristics and oral health behaviors (interest, lifestyle, diet, prevention), respectively, for a total of 101 items. RESULTS: The mean oral health literacy score was 44 (out of a maximum possible score of 72). Oral health literacy and oral health behaviors were positively correlated (r = 0.526, P < 0.001), and oral health literacy also had a significant effect on oral health behaviors (Beta = 0.26, 95% CI: 0.04-0.33). However, although functional oral health literacy had a significant effect on oral health behaviors (Beta = 0.20, 95% CI: 0.01-0.43), verbal oral health literacy did not (Beta = 0.13, 95% CI: - 0.06-037). CONCLUSIONS: Educational interventions are needed to improve oral health literacy, and thus oral health behaviors, as a part of the health promotion measures undertaken to facilitate the stable adjustment of North Korean defectors in South Korean society.

The association between Antonovsky's sense of coherence and job stress among dental hygienists in Korea.

OBJECTIVE: High stress levels experienced by medical professionals are a well-established phenomenon in current literature. However, there are few studies focusing on stress experienced in the field of oral health or on the sense of coherence (SOC) that helps to actively respond to job stress. The purpose of this study was to analyse if there is an association between SOC and job stress among dental hygienists in Korea. METHODS: A cross-sectional study was conducted on a convenience sample of 441 dental hygienists in the Seoul Gyeonggi province, Korea. The independent variable was SOC which had three dimensions: comprehensibility, manageability and meaningfulness. The dependent variable was job stress, which was evaluated using the Korean Occupational Stress Scale Short Form. Confounding factors were age, marital status, educational background, type of hospital, and work experience. The chi-square test and t test measures were used for bivariate analysis. Multiple logistic regression analysis was performed to confirm the association between SOC and job stress. The collected data were statistically analysed using SPSS version 22.0. RESULTS: The SOC score showed a significant difference in relation to the job stress score. The SOC score was high when the job stress was low (P < .001). Overall SOC scores showed an inverse correlation with job stress. CONCLUSION: This study reports that a higher SOC is associated with lower job stress in Korean dental hygienists. Since a higher SOC in dental hygienists indicated that they could cope with job stress more positively, it is important to increase their SOC.

The association between visual impairment and dental care utilization in the Korean elderly.

INTRODUCTION: Individuals with visual impairment cannot recognize early-stage oral diseases, thus fail to receive prompt treatment. AIMS: To evaluate the association between visual impairment and dental care utilization in patients aged ≥65 years. DESIGN: Retrospective analysis. MATERIALS AND METHODS: We analyzed annual pooled data collected by the Korean Health Panel between 2011 and 2014; a total of 1472 patients and 13,285 dental visits were analyzed. Visual impairment was categorized as follows: normal vision, moderate vision impairment, and severe vision impairment. Dental treatments were categorized as conservative, prosthodontic, implant, periodontal, surgical, preventive, or others. All data were statistically analyzed using a negative binomial regression. MAIN OUTCOME MEASURE: Frequency of dental care utilization. RESULTS: Approximately 50% of the subjects had visual impairment. The frequency of dental care utilization for patients with severe vision impairment was 41% less than patients with normal vision. The dental care utilization for implant treatment was two times higher and periodontal treatment was 1.7 times lower than the conservative treatments among patients who reported moderate and severe vision impairment, respectively. CONCLUSIONS: Visual impairment has a negative association with dental care utilization among older adults. It is imperative to implement systematic interventions to prevent visual impairment from becoming a barrier to dental care in this population.

Thymosin ß4 is associated with bone sialoprotein expression via ERK and Smad3 signaling pathways in MDPC-23 odontoblastic cells.

Thymosin ß4 (Tß4) regulates the expression of molecules associated with dentinogenesis, including bone sialoprotein (BSP). BSP regulates the initiation of mineralization and the direction of dentin growth. However, the association between Tß4 signaling and BSP expression in odontoblasts remains unclear. Therefore, the aim of the present study was to investigate Tß4 mRNA expression in odontoblasts during dentinogenesis and the association between the Tß4 signaling pathway and BSP expression in MDPC­23 odontoblastic cells. Expression and localization of Tß4 mRNA was determined by in situ hybridization during mouse tooth development. The effect of Tß4 signaling on BSP expression was investigated by reverse transcription polymerase chain reaction, western blot analysis, immunofluorescence and a luciferase reporter assay in the presence or absence of specific inhibitors of mitogen activated protein kinase kinase (PD98059) and mothers against decapentaplegic homolog 3 (Smad3; SIS3) in MDPC­23 cells. The expression of Tß4 mRNA in the odontoblast layer was highest at postnatal day 5, known as the advanced bell stage, when odontoblasts actively secrete dentin matrix proteins. Tß4 increased BSP mRNA and protein levels in MDPC­23 cells, but this was inhibited by PD98059 or SIS3 treatment. Tß4 increased levels of phosphorylated (p) extracellular signal­regulated kinase (ERK)1/2, pSmad3, pß­catenin, and runt­related transcription factor 2 (Runx2) protein, but these effects were inhibited by PD98059 or SIS3. Tß4 induced the nuclear translocation of Runx2 and pSmad3, while nuclear translocation of ß­catenin was decreased. Tß4 significantly increased BSP promoter activity, which was decreased by PD98059 or SIS3 treatment. Tß4 induced BSP expression in MDPC­23 cells via ERK and Smad3 signaling pathways, suggesting its role as a signaling molecule in odontoblasts for regulating BSP secretion during dentinogenesis.

AHNAK Loss in Mice Promotes Type II Pneumocyte Hyperplasia and Lung Tumor Development.

AHNAK is known to be a tumor suppressor in breast cancer due to its ability to activate the TGFß signaling pathway. However, the role of AHNAK in lung tumor development and progression remains unknown. Here, the Ahnak gene was disrupted to determine its effect on lung tumorigenesis and the mechanism by which it triggers lung tumor development was investigated. First, AHNAK protein expression was determined to be decreased in human lung adenocarcinomas compared with matched nonneoplastic lung tissues. Then, Ahnak -/- mice were used to investigate the role of AHNAK in pulmonary tumorigenesis. Ahnak -/- mice showed increased lung volume and thicker alveolar walls with type II pneumocyte hyperplasia. Most importantly, approximately 20% of aged Ahnak -/- mice developed lung tumors, and Ahnak -/- mice were more susceptible to urethane-induced pulmonary carcinogenesis than wild-type mice. Mechanistically, Ahnak deficiency promotes the cell growth of lung epithelial cells by suppressing the TGFß signaling pathway. In addition, increased numbers of M2-like alveolar macrophages (AM) were observed in Ahnak -/- lungs, and the depletion of AMs in Ahnak -/- lungs alleviated lung hyperplastic lesions, suggesting that M2-like AMs promoted the progression of lung hyperplastic lesions in Ahnak-null mice. Collectively, AHNAK suppresses type II pneumocyte proliferation and inhibits tumor-promoting M2 alternative activation of macrophages in mouse lung tissue. These results suggest that AHNAK functions as a novel tumor suppressor in lung cancer.Implications: The tumor suppressor function of AHNAK, in murine lungs, occurs by suppressing alveolar epithelial cell proliferation and modulating lung microenvironment. Mol Cancer Res; 16(8); 1287-98. ©2018 AACR.

Production of steviol from steviol glucosides using ß-glucosidase from a commercial pectinase, Sumizyme PX.

OBJECTIVE: To purify and characterize a specific enzyme from a commercial pectinase for the production of steviol from stevioside (Ste) without adding organic solvent and to improve steviol production. RESULTS: Commercial Sumizyme PX converted Ste to steviol with a yield of 98%. ß-Glucosidase from Sumizyme PX (ßglyPX) was purified in three steps with 12.5-fold purification and 51% yield. The specific activity of the purified ßglyPX was 141 U/mg. The molecular weight of ßglyPX was ~ 116 kDa on SDS-PAGE. Its optimum activity was at pH 3.5 and 65 °C. It was stable for 12 h up to 55 °C and for 24 h at pH 2-9.5. K m values of ßglyPX for pNPGal, oNPGlc, lactose, and Ste were 2.4, 0.7, 18, and 7.8 mM, respectively. The optimum conditions for steviol production were 55 °C, 900 U/ml, 80 mg Ste/ml, 12 h. CONCLUSION: ßglyPX contains great potential for industrial steviol production from Ste.

Inhibitory effect of flavonoids against NS2B-NS3 protease of ZIKA virus and their structure activity relationship.

OBJECTIVES: To determine the inhibitory activities of flavonoids against NS2B-NS3 protease of ZIKA virus (ZIKV NS2B-NS3pro) expressed in Escherichia coli BL21 (DE3) and their structure activity relationship. RESULTS: ZIKV NS2B-NS3pro was expressed in E. coli BL21(DE3) as a 35 kDa protein. It had a K m of 26 µM with the fluorogenic peptide Dabcyl-KTSAVLQSGFRKME-Edan. The purified ZIKV NS2B-NS3pro was used for inhibition and kinetic assays to determine the activities of 22 polyphenol compounds. These polyphenol compounds at 100 µM inhibited the activity of ZIKV NS2B-NS3pro by 6.2-88%. Seven polyphenol compounds had IC50 ranging from 22 ± 0.2 to 112 ± 5.5 µM. Myricetin showed a mixed type inhibitory pattern against ZIKV NS2B-NS3pro protease. Its IC50 value was 22 ± 0.2 µM with a K i value of 8.9 ± 1.9 µM. CONCLUSION: The chemical structure of a polyphenol compound and its inhibitory activity against ZIKV NS2B-NS3pro can be explored to develop highly selective inhibitors against ZIKV NS2B-NS3pro.

AHNAK deficiency promotes browning and lipolysis in mice via increased responsiveness to ß-adrenergic signalling.

In adipose tissue, agonists of the ß3-adrenergic receptor (ADRB3) regulate lipolysis, lipid oxidation, and thermogenesis. The deficiency in the thermogenesis induced by neuroblast differentiation-associated protein AHNAK in white adipose tissue (WAT) of mice fed a high-fat diet suggests that AHNAK may stimulate energy expenditure via development of beige fat. Here, we report that AHNAK deficiency promoted browning and thermogenic gene expression in WAT but not in brown adipose tissue of mice stimulated with the ADRB3 agonist CL-316243. Consistent with the increased thermogenesis, Ahnak(-/-) mice exhibited an increase in energy expenditure, accompanied by elevated mitochondrial biogenesis in WAT depots in response to CL-316243. Additionally, AHNAK-deficient WAT contained more eosinophils and higher levels of type 2 cytokines (IL-4/IL-13) to promote browning of WAT in response to CL-316243. This was associated with enhanced sympathetic tone in the WAT via upregulation of adrb3 and tyrosine hydroxylase (TH) in response to ß-adrenergic activation. CL-316243 activated PKA signalling and enhanced lipolysis, as evidenced by increased phosphorylation of hormone-sensitive lipase and release of free glycerol in Ahnak(-/-) mice compared to wild-type mice. Overall, these findings suggest an important role of AHNAK in the regulation of thermogenesis and lipolysis in WAT via ß-adrenergic signalling.

Regulation of c-Myc Expression by Ahnak Promotes Induced Pluripotent Stem Cell Generation.

We have previously reported that Ahnak-mediated TGFß signaling leads to down-regulation of c-Myc expression. Here, we show that inhibition of Ahnak can promote generation of induced pluripotent stem cells (iPSC) via up-regulation of endogenous c-Myc. Consistent with the c-Myc inhibitory role of Ahnak, mouse embryonic fibroblasts from Ahnak-deficient mouse (Ahnak(-/-) MEF) show an increased level of c-Myc expression compared with wild type MEF. Generation of iPSC with just three of the four Yamanaka factors, Oct4, Sox2, and Klf4 (hereafter 3F), was significantly enhanced in Ahnak(-/-) MEF. Similar results were obtained when Ahnak-specific shRNA was applied to wild type MEF. Of note, expressionof Ahnak was significantly induced during the formation of embryoid bodies from embryonic stem cells, suggesting that Ahnak-mediated c-Myc inhibition is involved in embryoid body formation and the initial differentiation of pluripotent stem cells. The iPSC from 3F-infected Ahnak(-/-) MEF cells (Ahnak(-/-)-iPSC-3F) showed expression of all stem cell markers examined and the capability to form three primary germ layers. Moreover, injection of Ahnak(-/-)-iPSC-3F into athymic nude mice led to development of teratoma containing tissues from all three primary germ layers, indicating that iPSC from Ahnak(-/-) MEF are bona fide pluripotent stem cells. Taken together, these data provide evidence for a new role for Ahnak in cell fate determination during development and suggest that manipulation of Ahnak and the associated signaling pathway may provide a means to regulate iPSC generation.

Down regulation of Jag-1 in VSMCs contributes to impaired angiogenesis under high glucose condition: Experimental study using aortic rings of rats.

The major cause of diabetes-related mortality is the complications involving aberrant angiogenesis. To understand the underlying mechanisms of such altered-angiogenesis in diabetes, examining the interaction between endothelial cells (ECs) and neighboring smooth muscle cells (VSMCs) rather than mainly focusing on EC might provide us useful information. Thus, in the present study, we examined the effect of high glucose on the expression of Jag1, one of the key trans-activating ligands of Notch receptors known to be involved in EC-SMC interaction, as well as angiogenic process, in vascular smooth muscle cells (VSMCs) to elucidate possible role of EC-VSMC interaction in diabetes-related angiopathy. Our data indicate that high glucose condition decreases the expression of Jag1 in VSMCs possibly by increasing Jag1-targeting micro RNAs (miRNAs) such as miR-21, and exogenous Jag1-simulating peptides increase proliferation and migration of ECs under high glucose condition in vitro. Ex vivo study using aortic rings from normal and streptozotocin (STZ)-treated diabetic mouse demonstrated that exogenous Jag1-simulating peptides increases EC sprouting of aortic rings from diabetic mouse under high glucose condition. Our data suggest that EC-VSMC interaction is altered under high glucose condition and restoring EC-VSMC interaction can be a feasible therapeutic target for treating diabetes-related angiopathy.

Interaction of NADPH oxidase 1 with Toll-like receptor 2 induces migration of smooth muscle cells.

AIMS: NADPH oxidase (Nox) isozymes that generate intracellular reactive oxygen species (ROS) and Toll-like receptor 2 (TLR2), an inflammatory mediator, are both involved in the development of atherosclerotic lesions. To identify the molecular connection between TLR2 and Nox isozymes in vascular remodelling, we analysed generation of ROS and pro-inflammatory cytokines in aortic smooth muscle cells from Nox1-deficient mice in response to the synthetic triacylated lipoprotein Pam3CSK, a TLR2 agonist. METHODS AND RESULTS: We showed that TLR2 signalling stimulates progression of the pro-inflammatory phenotype in mouse aortic smooth muscle cells (MASMCs) through activation of Nox1. We demonstrated the interaction of TLR2 with Nox1 using yeast two-hybrid and co-immunoprecipitation assays. MASMCs from Nox1-deficient mice failed to generate of ROS in response to Pam3CSK4, indicating that Nox1 is essential for TLR2-dependent production of ROS. We also found that Pam3CSK4 stimulated migration of MASMCs from wild-type mice in a Transwell system, but MASMCs from Nox1-deficient mice failed to show this response. Wild-type MASMCs produced matrix metalloprotease 2 in response to Pam3CSK4, whereas Nox1-deficient MASMCs failed to generate this protease. Moreover, stimulation of MASMCs with Pam3CSK4 resulted in increased expression of the pro-inflammatory cytokine macrophage inflammatory protein 2 in a Nox1-dependent manner, leading to enhanced monocyte-endothelial cell adhesion and trans-endothelial migration of U937 cells. CONCLUSION: These data suggest that Nox1 plays an important role in TLR2-mediated intracellular H2O2 generation, activation of matrix metalloprotease 2, and secretion of pro-inflammatory cytokines, which in turn stimulate MASMC migration and vascular remodelling.

Function of Ahnak protein in aortic smooth muscle cell migration through Rac activation.

AIMS: Ahnak protein acts as a scaffold protein networking phospholipase C-γ and protein kinase C-α, which subsequently stimulate an extracellular signal-regulated kinase (Erk) pathway. In mouse aortic smooth muscle cells (ASMCs), the activation of the signalling cascade ultimately promotes the cell migration through an unknown mechanism. We aimed to dissect the Ahnak-mediated cell signalling network involved in the migration of ASMCs. METHODS AND RESULTS: Migration of ASMCs from wild-type mice was significantly increased by platelet-derived growth factor (PDGF) stimulation in transwell chamber and wound-healing assays, whereas migration of ASMCs from Ahnak knockout mice was reduced. Consistently, stimulation of wild-type ASMCs with PDGF resulted in Rac activation-mediated lamellipodial protrusion in migrating cells. In contrast, Ahnak knockout ASMCs displayed lower activation of Rac in response to PDGF and slow lamellipodial protrusion rate and cell migration. Ahnak signalling complex was analysed by immunoprecipitation with antibody to p21-activated protein kinase (PAK). Ahnak protein was shown to function as the signalling scaffold interacting with the multiple protein complex of Erk, PAK, and p21-activated kinase-interacting exchange factor ß. The proposed role of Ahnak in cell migration was examined using a restenosis model in which the carotid arteries of mice were subjected to post-ligation injury. We show neointimal formation and SMC migration after ligation injury in Ahnak knockout mice were significantly retarded compared with wild-type mice. CONCLUSION: Ahnak protein plays an important scaffolding function connecting Erk and Rac activation in PDGF-dependent migration of ASMC.

Ahnak protein activates protein kinase C (PKC) through dissociation of the PKC-protein phosphatase 2A complex.

We have previously reported that central repeated units (CRUs) of Ahnak act as a scaffolding protein networking phospholipase Cgamma and protein kinase C (PKC). Here, we demonstrate that an Ahnak derivative consisting of four central repeated units binds and activates PKC-alpha in a phosphatidylserine/1,2-dioleoyl-sn-glycerol-independent manner. Moreover, NIH3T3 cells expressing the 4 CRUs of Ahnak showed enhanced c-Raf, MEK, and Erk phosphorylation in response to phorbol 12-myristate 13-acetate (PMA) compared with parental cells. To evaluate the effect of loss-of-function of Ahnak in cell signaling, we investigated PKC activation and Raf phosphorylation in embryonic fibroblast cells (MEFs) of the Ahnak knock-out (Ahnak(-/-)) mouse. Membrane translocation of PKC-alpha and phosphorylation of Raf in response to PMA or platelet-derived growth factor were decreased in Ahnak null MEF cells compared with wild type MEFs. Several lines of evidence suggest that PKC-alpha activity is regulated through association with protein phosphatase 2A (PP2A). A co-immunoprecipitation assay indicated that the association of PKC-alpha with PP2A was disrupted in NIH3T3 cells expressing 4 CRUs of Ahnak in response to PMA. Consistently, Ahnak null MEF cells stimulated by PMA showed enhanced PKC-PP2A complex formation, and add-back expression of Ahnak into Ahnak null MEF cells abolished the PKC-PP2A complex formation in response to PMA. These data indicate that Ahnak potentiates PKC activation through inhibiting the interaction of PKC with PP2A.

Development of anthropometry-based equations for the estimation of the total body water in Koreans.

For developing race-specific anthropometry-based total body water (TBW) equations, we measured TBW using bioelectrical impedance analysis (TBW(BIA)) in 2,943 healthy Korean adults. Among them, 2,223 were used as a reference group. Two equations (TBW(K1) and TBW(K2)) were developed based on age, sex, height, and body weight. The adjusted R2 was 0.908 for TBW(K1) and 0.910 for TBW(K2). The remaining 720 subjects were used for the validation of our results. Watson (TBW(W)) and Hume-Weyers (TBW(H)) formulas were also used. In men, TBW(BIA) showed the highest correlation with TBW(H), followed by TBW(K1), TBW(K2) and TBW(W). TBW(K1) and TBW(K2) showed the lower root mean square errors (RMSE) and mean prediction errors (ME) than TBW(W) and TBW(H). On the Bland-Altman plot, the correlations between the differences and means were smaller for TBW(K2) than for TBW(K1). On the contrary, TBW(BIA) showed the highest correlation with TBW(W), followed by TBW(K2), TBW(K1), and TBW(H) in females. RMSE was smallest in TBW(W), followed by TBW(K2), TBW(K1) and TBW(H). ME was closest to zero for TBW(K2), followed by TBW(K1), TBW(W) and TBW(H). The correlation coefficients between the means and differences were highest in TBW(W), and lowest in TBW(K2). In conclusion, TBW(K2) provides better accuracy with a smaller bias than the TBW(W) or TBW(H) in males. TBW(K2) shows a similar accuracy, but with a smaller bias than TBW(W) in females.

Plasma brain natriuretic peptide concentration on assessment of hydration status in hemodialysis patient.

BACKGROUND: Brain natriuretic peptide (BNP) is released into circulation in response to ventricular dilatation and pressure overload. Plasma BNP concentration correlates with left ventricular mass and dysfunction, which is prevalent in hemodialysis (HD) patients. METHODS: To evaluate the potential of BNP level for determination of hydration status, we measured inferior vena caval diameter (IVCD) and BNP levels and performed bioimpedance analysis in 49 HD patients. RESULTS: Pre-HD BNP levels remained unchanged after HD. Agreement between IVCD and pre-HD BNP level in overhydration was significant (kappa = 0.304). The area under the receiver operating characteristic (ROC) curve for overhydration was 0.819 for pre-HD BNP level. When extracellular fluid/total-body water (ECF/TBW) ratios of HD patients were compared with those of 723 controls, pre- and post-HD BNP levels were significantly greater in overhydrated patients. The area under the ROC curve for overhydration by ECF/TBW ratio was 0.781 for pre-HD BNP level. However, there was no significance for pre- or post-HD BNP levels on assessment of normohydration or underhydration. Pre-HD BNP level correlated significantly with post-HD BNP level, post-HD diastolic blood pressure, pulse pressure, and ECF/TBW ratio. IVCD correlated significantly with post-HD BNP level. CONCLUSION: BNP level seems to have a limited potential for assessment of overhydration in HD patients.