Open conformers of HLA-F are high-affinity ligands of the activating NK-cell receptor KIR3DS1.

The activating natural killer (NK)-cell receptor KIR3DS1 has been linked to the outcome of various human diseases, including delayed progression of disease caused by human immunodeficiency virus type 1 (HIV-1), yet a ligand that would account for its biological effects has remained unknown. We screened 100 HLA class I proteins and found that KIR3DS1 bound to HLA-F, a result we confirmed biochemically and functionally. Primary human KIR3DS1(+) NK cells degranulated and produced antiviral cytokines after encountering HLA-F and inhibited HIV-1 replication in vitro. Activation of CD4(+) T cells triggered the transcription and surface expression of HLA-F mRNA and HLA-F protein, respectively, and induced binding of KIR3DS1. HIV-1 infection further increased the transcription of HLA-F mRNA but decreased the binding of KIR3DS1, indicative of a mechanism for evading recognition by KIR3DS1(+) NK cells. Thus, we have established HLA-F as a ligand of KIR3DS1 and have demonstrated cell-context-dependent expression of HLA-F that might explain the widespread influence of KIR3DS1 in human disease.

Lipidomic Analysis of α-Synuclein Neurotoxicity Identifies Stearoyl CoA Desaturase as a Target for Parkinson Treatment.

In Parkinson's disease (PD), α-synuclein (αS) pathologically impacts the brain, a highly lipid-rich organ. We investigated how alterations in αS or lipid/fatty acid homeostasis affect each other. Lipidomic profiling of human αS-expressing yeast revealed increases in oleic acid (OA, 18:1), diglycerides, and triglycerides. These findings were recapitulated in rodent and human neuronal models of αS dyshomeostasis (overexpression; patient-derived triplication or E46K mutation; E46K mice). Preventing lipid droplet formation or augmenting OA increased αS yeast toxicity; suppressing the OA-generating enzyme stearoyl-CoA-desaturase (SCD) was protective. Genetic or pharmacological SCD inhibition ameliorated toxicity in αS-overexpressing rat neurons. In a C. elegans model, SCD knockout prevented αS-induced dopaminergic degeneration. Conversely, we observed detrimental effects of OA on αS homeostasis: in human neural cells, excess OA caused αS inclusion formation, which was reversed by SCD inhibition. Thus, monounsaturated fatty acid metabolism is pivotal for αS-induced neurotoxicity, and inhibiting SCD represents a novel PD therapeutic approach.

Dissecting the stability determinants of a challenging de novo protein fold using massively parallel design and experimentation.

Designing entirely new protein structures remains challenging because we do not fully understand the biophysical determinants of folding stability. Yet, some protein folds are easier to design than others. Previous work identified the 43-residue ɑßßɑ fold as especially challenging: The best designs had only a 2% success rate, compared to 39 to 87% success for other simple folds [G. J. Rocklin et al., Science 357, 168-175 (2017)]. This suggested the ɑßßɑ fold would be a useful model system for gaining a deeper understanding of folding stability determinants and for testing new protein design methods. Here, we designed over 10,000 new ɑßßɑ proteins and found over 3,000 of them to fold into stable structures using a high-throughput protease-based assay. NMR, hydrogen-deuterium exchange, circular dichroism, deep mutational scanning, and scrambled sequence control experiments indicated that our stable designs fold into their designed ɑßßɑ structures with exceptional stability for their small size. Our large dataset enabled us to quantify the influence of universal stability determinants including nonpolar burial, helix capping, and buried unsatisfied polar atoms, as well as stability determinants unique to the ɑßßɑ topology. Our work demonstrates how large-scale design and test cycles can solve challenging design problems while illuminating the biophysical determinants of folding.

Strategic combination of bacteriophages with highly susceptible cells for enhanced intestinal settlement and resistant cell killing.

Avian pathogenic Escherichia coli (APEC) causes enormous economic losses and is a primary contributor to the emergence of multidrug resistance (MDR)-related problems in the poultry industry. Bacteriophage (phage) therapy has been successful in controlling MDR, but phage-resistant variants have rapidly emerged through the horizontal transmission of diverse phage defense systems carried on mobile genetic elements. Consequently, while multiple phage cocktails are recommended for phage therapy, there is a growing need to explore simpler and more cost-effective phage treatment alternatives. In this study, we characterized two novel O78-specific APEC phages, φWAO78-1 and φHAO78-1, in terms of their morphology, genome, physicochemical stability and growth kinetics. Additionally, we assessed the susceptibility of thirty-two O78 APEC strains to these phages. We analyzed the roles of highly susceptible cells in intestinal settlement and fecal shedding (susceptible cell-assisted intestinal settlement and shedding, SAIS) of phages in chickens via coinoculation with phages. Furthermore, we evaluated a new strategy, susceptible cell-assisted resistant cell killing (SARK), by comparing phage susceptibility between resistant cells alone and a mixture of resistant and highly susceptible cells in vitro. As expected, high proportions of O78 APEC strains had already acquired multiple phage defense systems, exhibiting considerable resistance to φWAO78-1 and φHAO78-1. Coinoculation of highly susceptible cells with phages prolonged phage shedding in feces, and the coexistence of susceptible cells markedly increased the phage susceptibility of resistant cells. Therefore, the SAIS and SARK strategies were demonstrated to be promising both in vivo and in vitro.

Lung cancer-specific symptoms and fear of cancer recurrence among recurrence-free non-small cell lung cancer survivors.

PURPOSE: Lung cancer survivors have more psychosocial problems, including depression and anxiety disorder, than other cancer survivors. Lung cancer-specific symptoms, such as cough, dyspnea, or pain in chest, might increase FCR among survivors. We aimed to evaluate the association between lung cancer-specific symptoms and FCR among recurrence-free non-small cell lung cancer (NSCLC) survivors. METHODS: This is a cross-sectional study. Recurrence-free NSCLC survivors were recruited from January to October 2020 at a tertiary hospital in Seoul, Korea. We measured FCR using the Korean version of FCRI-SF and categorized them into three groups: non-clinical FCR (nFCR, < 13), subclinical FCR (sFCR, 13 to 21), and clinical FCR (cFCR, ≥ 22). Lung cancer-specific symptoms were measured using the Korean version of EORTC QLQ-LC13 and EORTC QLQ-C30. RESULTS: A total of 727 survivors were enrolled. One-third (30.8%) of survivors reported sFCR, and 19.7% had cFCR. In a multivariate analysis, survivors with severe pain in chest were 4.7 times (95% CI: 2.4-9.0) more likely to experience cFCR compared to those without it. Mild dyspnea (OR 1.7, 95% CI: 1.1-2.7) and mild dysphagia (OR 2.4, 95% CI: 1.3-4.4) were associated with cFCR. Survivors with sFCR (Coef. - 6.3, 95% CI: - 9.8, - 2.8) and cFCR (Coef. - 11.3, 95% CI: - 15.5, - 7.2) had poorer quality of life compared to survivors with nFCR. CONCLUSION: NSCLC survivors were experiencing lung cancer-specific symptoms even a few years after treatment, which were associated with cFCR, resulting in poor HRQoL. It is necessary to develop a lung cancer-specific symptom checklist and use it during even long-term surveillance.

Obstetric factors and neonatal outcomes of depressed skull fractures in newborns.

PURPOSE: To determine the obstetric factors affecting the development of depressed skull fracture in neonates. MATERIALS AND METHODS: This was a retrospectively cohort study on neonates born between July 2016 and August 2021. Neonates diagnosed with depressed skull fractures within one week of birth through X-ray and/or brain ultrasonography were included, and their mothers' obstetric characteristics were reviewed. RESULTS: There were 12 cases in 6791 live births. Five women were over 35 years old. All except two were nulliparous. Five cases were delivered from labor induction and others presented with spontaneous labor. Except for two cases, delivery occurred within an hour after full cervical dilatation. Two cases were assisted by vacuum. None displayed fetal distress signs such as low Apgar scores below 7, meconium staining, and umbilical cord pH under 7.2. All depressed fractures were found in the right parietal area. Three cases resulted in focal hyperechoic lesion in brain ultrasonography and two of them showed small hemorrhage-like lesion in magnetic resonance imaging. All depressed skull fractures improved within 6 months in followed X-rays or ultrasonography. CONCLUSIONS: There was no definitely associated obstetric condition for depressed skull fracture of neonates although nulliparous women were majority of the affected cases.

Excess membrane binding of monomeric alpha-, beta- and gamma-synuclein is invariably associated with inclusion formation and toxicity.

α-Synuclein (αS) has been well-documented to play a role in human synucleinopathies such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB). First, the lesions found in PD/DLB brains-Lewy bodies and Lewy neurites-are rich in aggregated αS. Second, genetic evidence links missense mutations and increased αS expression to familial forms of PD/DLB. Third, toxicity and cellular stress can be caused by αS under certain experimental conditions. In contrast, the homologs ß-synuclein (ßS) and γ-synuclein (γS) are not typically found in Lewy bodies/neurites, have not been clearly linked to brain diseases and have been largely non-toxic in experimental settings. In αS, the so-called non-amyloid-ß component of plaques (NAC) domain, constituting amino acids 61-95, has been identified to be critical for aggregation in vitro. This domain is partially absent in ßS and only incompletely conserved in γS, which could explain why both homologs do not cause disease. However, αS in vitro aggregation and cellular toxicity have not been firmly linked experimentally, and it has been proposed that excess αS membrane binding is sufficient to induce neurotoxicity. Indeed, recent characterizations of Lewy bodies have highlighted the accumulation of lipids and membranous organelles, raising the possibility that ßS and γS could also become neurotoxic if they were more prone to membrane/lipid binding. Here, we increased ßS and γS membrane affinity by strategic point mutations and demonstrate that these proteins behave like membrane-associated monomers, are cytotoxic and form round cytoplasmic inclusions that can be prevented by inhibiting stearoyl-CoA desaturase.

Different Impact of Metabolic Syndrome on the Risk of Incidence of the Peripheral Artery Disease and the Venous Thromboembolism: A Nationwide Longitudinal Cohort Study in South Korea.

Background: Limited data is available between metabolic syndrome (MetS) and the development of peripheral arterial disease (PAD) or venous thromboembolism (VTE) in the Asian population. We investigated the incidence of PAD and VTE according to the prevalence of MetS and evaluated the impact of individual components in MetS on the development of PAD and VTE using Korean national data. Methods: Data obtained from national health screening examinations of the Korean National Health Insurance Service from January 1, to December 31, 2009. In total, 9,927,538 participants, 7,830,602 participants were included in this study and the incidence rate of PAD and VTE was investigated retrospectively during a 7-year follow-up. Using the National Cholesterol Education Program Adult Treatment Panel III criteria, patients were placed into one of three groups depending on MetS component numbers: 0 (normal), 1-2 (Pre-MetS), or 3-5 (MetS). Results: The incidence rates of PAD and VTE in MetS were 2.25% and 0.71%, respectively. After multivariable adjustment, the risk of PAD was significantly associated with MetS (hazard ratio (HR) 1.45, 95% confidence interval (CI) 1.42-1.49), the risk of VTE was not associated with MetS (HR 1.01, 95% CI 0.96-1.05). When subgroup analyses were conducted according to MetS components, elevated fasting glucose (HR 1.26, 95% CI 1.23-1.27), abdominal obesity (HR 1.15, 95% CI 1.12-1.17), and elevated blood pressure (HR 1.13, 95% CI 1.12-1.15) were the most related to PAD. Abdominal obesity (HR 1.104, 95% CI 1.064-1.146) was associated with an increased risk of VTE. Conclusions: MetS was significantly associated with an increased incidence rate of PAD among the general Korean population. On the other hand, MetS was not associated with the VTE incidence rate. Of the MetS components, only abdominal obesity was a significant predictor of VTE.

Analysis of facial vascular pattern characteristics in the Korean population.

BACKGROUND: Facial erythema is a common problem among patients visiting dermatologists. However, data on the clinical characteristics of facial erythema in healthy people are lacking. We aimed to compare and analyze the severity and pattern of facial vascularity in healthy subjects based on their age and gender. MATERIALS AND METHODS: This study included 198 Korean volunteers (126 females and 72 males) with Fitzpatrick skin types II, III, or IV. Fourteen different anatomical areas on the face were divided into facial erythema units. Each unit was scored from one (least erythematous) to five (most erythematous) according to the observed level of erythema on the red images implemented as hemoglobin content. We also evaluated the presence of facial telangiectatic macules. RESULTS: On average, the perinasal, nasal, and cheek units were the most hypervascular regions. In contrast, the degree of facial erythema was lowest in the labial (perioral), neck, and temporal regions. The average value of erythema was higher in males than in females. Additionally, the severity of erythema tended to increase with age. In both males and females, the number of telangiectatic macules increased with age. CONCLUSIONS: We analyzed the clinical characteristics of erythema in healthy subjects with Fitzpatrick skin types II, III, or IV in the Korean population. This study is expected to be used to identify the neurovascular pathogenesis of the most common regions of facial dermatosis in the future.

Impact of bevacizumab and secondary cytoreductive surgery on survival outcomes in platinum-sensitive relapsed ovarian clear cell carcinoma: A multicenter study in Korea.

OBJECTIVE: This study investigated survival outcomes for platinum-sensitive relapsed ovarian clear cell carcinoma (OCCC) by treatment method. METHODS: OCCC patients with platinum-sensitive recurrence that received secondary treatment at five institutions between July 2007 and June 2021 were included. Patient characteristics and survival outcomes were compared according to the use of bevacizumab (BEV) during second-line chemotherapy and secondary cytoreductive surgery (CRS). RESULTS: 138 patients were included. The BEV (n = 36) and non-BEV (n = 102) groups had similar initial FIGO stages and proportions of secondary CRS. The BEV group showed improved progression-free survival (PFS; median, 15.4 vs. 7.5 months; P = 0.042) and overall survival (OS; P = 0.043) compared to the non-BEV group. In multivariate analyses, BEV was identified as an independent prognostic factor for PFS (adjusted hazard ratio [aHR], 0.571; 95% confidence interval [CI], 0.354-0.921; P = 0.022) and OS (aHR, 0.435; 95%CI, 0.195-0.970; P = 0.042). The secondary CRS group (n = 42) had early-stage disease at diagnosis more frequently (P = 0.009) and multi-site metastasis (P < 0.001) at recurrence less frequently than the no surgery group (n = 96). The secondary CRS group showed significantly better PFS (median, 33.7 vs. 7.2 months; P < 0.001) and OS (P < 0.001). Secondary CRS was associated with a significantly improved PFS (aHR, 0.297; 95% CI, 0.183-0.481; P < 0.001) and OS (aHR, 0.276; 95% CI, 0.133-0.576; P = 0.001). The BEV and non-BEV groups showed similar PFS and OS among the patients who underwent secondary CRS. In contrast, the BEV group showed improved PFS and OS among patients who did not undergo surgery. CONCLUSIONS: The use of BEV during second-line chemotherapy and secondary CRS may improve PFS and OS in patients with platinum-sensitive relapsed OCCC. Further prospective studies are warranted.

Cell models of lipid-rich α-synuclein aggregation validate known modifiers of α-synuclein biology and identify stearoyl-CoA desaturase.

Microscopy of Lewy bodies in Parkinson's disease (PD) suggests they are not solely filamentous deposits of α-synuclein (αS) but also contain vesicles and other membranous material. We previously reported the existence of native αS tetramers/multimers and described engineered mutations of the αS KTKEGV repeat motifs that abrogate the multimers. The resultant excess monomers accumulate in lipid membrane-rich inclusions associated with neurotoxicity exceeding that of natural familial PD mutants, such as E46K. Here, we use the αS "3K" (E35K+E46K+E61K) engineered mutation to probe the mechanisms of reported small-molecule modifiers of αS biochemistry and then identify compounds via a medium-throughput automated screen. αS 3K, which forms round, vesicle-rich inclusions in cultured neurons and causes a PD-like, l-DOPA-responsive motor phenotype in transgenic mice, was fused to YFP, and fluorescent inclusions were quantified. Live-cell microscopy revealed the highly dynamic nature of the αS inclusions: for example, their rapid clearance by certain known modulators of αS toxicity, including tacrolimus (FK506), isradipine, nilotinib, nortriptyline, and trifluoperazine. Our automated 3K cellular screen identified inhibitors of stearoyl-CoA desaturase (SCD) that robustly prevent the αS inclusions, reduce αS 3K neurotoxicity, and prevent abnormal phosphorylation and insolubility of αS E46K. SCD inhibition restores the E46K αS multimer:monomer ratio in human neurons, and it actually increases this ratio for overexpressed wild-type αS. In accord, conditioning 3K cells in saturated fatty acids rescued, whereas unsaturated fatty acids worsened, the αS phenotypes. Our cellular screen allows probing the mechanisms of synucleinopathy and refining drug candidates, including SCD inhibitors and other lipid modulators.

Serum 25-Hydroxy Vitamin D Levels and Association of Vitamin D Receptor Gene Polymorphisms in Vitiligo.

BACKGROUND: The role of vitamin D deficiency and vitamin D receptor (VDR) gene polymorphisms has been established in many autoimmune diseases, including vitiligo, but the result is still controversial. OBJECTIVES: The aim of this study was to investigate the serum vitamin D levels in vitiligo patients and to compare the association of VDR gene polymorphisms in vitiligo patients and healthy controls. METHODS: We collected the data of age, sex, serum 25-hydroxy vitamin D (25[OH]D) level, thyroid autoantibodies, disease duration, types of vitiligo, family history and the affected body surface area of vitiligo from 172 patients. And we analyzed the VDR gene polymorphisms in 130 vitiligo and 453 age-sex-matched control subjects. RESULTS: The mean serum level of 25(OH)D in 172 vitiligo patients was 18.75 ± 0.60 ng/mL, which had no significant difference with a mean serum value of 25(OH)D in the Korean population. However, there were significant differences according to the duration of the disease and family history. Also, there were no significant differences in the genotypic and allelic distributions of 37 examined SNPs of VDR gene between vitiligo patients and healthy controls. CONCLUSION: Serum level of 25(OH)D in vitiligo patients was not significantly different from the mean serum value of the Korean population. Also, there were no significant differences in the genotypic distributions of VDR gene between vitiligo patients and healthy controls.

Cholecalciferol- and α-tocopherol-loaded walnut oil emulsions stabilized by whey protein isolate and soy lecithin for food applications.

BACKGROUND: To overcome the limitations in the use of protein as an emulsifier, soy lecithin, a natural surfactant, was used along with whey protein isolate (WPI) to produce o/w emulsions containing cholecalciferol and α-tocopherol. The physical stability of the emulsions prepared with WPI and varying concentrations of lecithin (0, 1, 2, and 3% w/w) was measured in different heat, pH, and ionic-strength food environmental conditions. RESULTS: All emulsions were shown to be less than 250 nm in size and less than 0.3 in polydispersity index (PDI). The morphology of the emulsions was spherical, and the droplets of the emulsion containing lecithin were thicker and larger than those of the emulsion without lecithin (WPI_L0). After autoclaving, WPI_L0 increased in size from 197.8 ± 1.7 nm to 528.5 ± 28.4 nm, and the retention of cholecalciferol and α-tocopherol decreased to 40.83 ± 0.63% and 49.68 ± 1.84%, respectively. At pH 5.5, near the isoelectric point of WPI, WPI_L0 increased in size due to aggregation, but emulsions containing lecithin remained stable at a PDI under 0.3. Turbiscan stability index of the emulsion prepared with WPI and 3% lecithin was the lowest, indicating good storage stability. In addition, it was confirmed that the higher the lecithin content, the higher the viscosity, and the higher the amount of free fatty acids released in the in vitro digestion model. CONCLUSION: This study can provide theoretical evidence for enhancing the physical stability of protein emulsions by co-stabilization with lecithin, promoting their application in various foods. © 2022 Society of Chemical Industry.

Reports of anaphylaxis after coronavirus disease 2019 vaccination, South Korea, 26 February to 30 April 2021.

The South Korea mass vaccination programme administered 3.8 million doses of COVID-19 vaccinations between 26 February and 30 April 2021. After 173 suspected anaphylaxis reports to the nationwide monitoring system for adverse events following immunisation, 44 anaphylaxis cases were confirmed using Brighton Collaboration case definitions. The rates per million doses were 18.2 cases and 6.2 cases for Vaxzevria and Comirnaty, respectively. Median time of onset was 14 min after vaccination and most cases had recovered at the time of review.

Vaccine-related Anaphylaxis Cases Confirmed by KCDC from 2001-2016.

BACKGROUND: A national immunization program (NIP) to prevent disease and reduce mortality from vaccine preventable diseases (VPD) is very important. METHODS: We analyzed only the anaphylaxis cases that occurred between 2001 and 2016 that Korea Centers for Disease Control and Prevention (KCDC) determined had a definite causal relationship with a vaccine. The clinical symptoms were assessed according to the Brighton Collaboration case definition (BCCD) level. RESULTS: During the period, there were 13 cases of vaccine-related anaphylaxis. The median age was 9 years (range, 1 month to 59 years). The incidence of anaphylaxis per million doses was 0.090 in 2005, 0.079 in 2012, 0.071 in 2013, 0.188 in 2015, and 0.036 in 2016. Of those cases, 23.1% were influenza vaccines, and 76.9% were BCCD level 2. Epinephrine was used in 46.2%. CONCLUSION: Vaccine-related anaphylaxis seems to have been very rare in the past, but health care professionals must always be aware of anaphylaxis.

Clinical Role of the Chronic Obstructive Pulmonary Disease Assessment Test in Prediction of the Response to Treatment for Exacerbations.

BACKGROUND: The chronic obstructive pulmonary disease (COPD) assessment test (CAT) is a validated, eight-item questionnaire used to quantify the health status of patients. The aim of this study was to evaluate the usefulness of the CAT questionnaire as a tool to assess the response to treatment in acute exacerbations of COPD in an outpatient setting. METHODS: A multicenter, phase 3 randomized controlled trial was conducted previously to examine the efficacy and safety of oral zabofloxacin for the treatment of COPD exacerbations. In the present post hoc analysis of the original study, patients with COPD exacerbation were categorized as responders or non-responders according to the respiratory symptoms persisting on day 10 (visit 3) of treatment. The CAT questionnaire was completed daily by patients at home from the initial visit to the second visit on day 5. Subsequently, the questionnaire was completed in the presence of a physician on days 10 (visit 3) and 36 (visit 4). Multivariate regression analysis was performed to determine the association between CAT scores and the therapeutic response. RESULTS: The CAT scores decreased more rapidly in responders compared to non-responders during the first 5 days (23.3-20.4 vs. 23.5-22). Among responders, patients with higher severity of illness also revealed higher CAT scores on the first day of an exacerbation (mild, 19.8; moderate, 21.4; severe, 23.8; very severe, 28.6). Multivariate analysis revealed that a change in the CAT score during the first 3 days influenced the therapeutic response. A significant decrease in scores in the domains of sputum production, chest tightness, and activities of daily living was seen among responders. CONCLUSION: Early improvement in CAT scores may be associated with a more favorable response to the treatment of COPD exacerbations. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01658020. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0000532.

Bioanalytical Method Using Ultra-High-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry (UHPL-CHRMS) for the Detection of Metformin in Human Plasma.

Metformin is the first-line medicine for the treatment of type 2 diabetes. Drug interactions between metformin and other drugs, food, or beverages cannot only cause changes in the pharmacokinetic profiles but also affect the efficacy of metformin. The purpose of this study was to develop a rapid and reliable bioanalytical method for the detection of plasma metformin concentration in humans. To remove interfering substances in plasma, acidified acetonitrile (acetonitrile containing 0.1% formic acid) was added to samples. Ultra-high-performance liquid chromatography (UHPLC) coupled with high resolution mass spectrometry (HRMS) was used to analyze metformin and its internal standard (metformin-d6). Analyte separation was performed on a BEH HILIC analytical column (100 × 2.1 mm, 1.7 µm) using a gradient elution of 0.1% formic acid (A) and acetonitrile with 0.1% formic acid (B). The total chromatographic run time was 2 min. The developed method was validated for its linearity, accuracy and precision, selectivity (signal of interfering substance; analyte, lower limit of quantification (LLOQ) ≤ 20%; IS, IS ≤ 5%), sensitivity (LLOQ, 5 ng/mL; S/N ratio ≥ 10), stability (low quality control (LQC, 15 ng/mL), 2.95-14.19%; high quality control (HQC, 1600 ng/mL), -9.49-15.10%), dilution integrity (diluted QC (4000 ng/mL); 10-folds diluted QC (400 ng/mL); 5-folds diluted QC (800 ng/mL); accuracy, 81.30-91.98%; precision, ≤4.47%), carry-over (signal of double blank; analyte, LLOQ ≤20%; IS, IS ≤5%), and matrix effect (LQC, 10.109%; HQC, 12.271%) under various conditions. The constructed calibration curves were shown linear in the concentration range of 5-2000 ng/mL, with within- and between-run precision values of <8.19% and accuracy in the range of 91.13-105.25%. The plasma metformin concentration of 16 healthy subjects was successfully measured by applying the validated bioanalytical method.

Dynamic behaviors of α-synuclein and tau in the cellular context: New mechanistic insights and therapeutic opportunities in neurodegeneration.

α-Synuclein (αS) and tau have a lot in common. Dyshomeostasis and aggregation of both proteins are central in the pathogenesis of neurodegenerative diseases: Parkinson's disease, dementia with Lewy bodies, multi-system atrophy and other 'synucleinopathies' in the case of αS; Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy and other 'tauopathies' in the case of tau. The aggregated states of αS and tau are found to be (hyper)phosphorylated, but the relevance of the phosphorylation in health or disease is not well understood. Both tau and αS are typically characterized as 'intrinsically disordered' proteins, while both engage in transient interactions with cellular components, thereby undergoing structural changes and context-specific folding. αS transiently binds to (synaptic) vesicles forming a membrane-induced amphipathic helix; tau transiently interacts with microtubules forming an 'extended structure'. The regulation and exact nature of the interactions are not fully understood. Here we review recent and previous insights into the dynamic, transient nature of αS and tau with regard to the mode of interaction with their targets, the dwell-time while bound, and the cis and trans factors underlying the frequent switching between bound and unbound states. These aspects are intimately linked to hypotheses on how subtle changes in the transient behaviors may trigger the earliest steps in the pathogenesis of the respective brain diseases. Based on a deeper understanding of transient αS and tau conformations in the cellular context, new therapeutic strategies may emerge, and it may become clearer why existing approaches have failed or how they could be optimized.

Loss of native α-synuclein multimerization by strategically mutating its amphipathic helix causes abnormal vesicle interactions in neuronal cells.

α-Synuclein (αS) forms round cytoplasmic inclusions in Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Evidence suggests a physiological function of αS in vesicle trafficking and release. In contrast to earlier tenets, recent work indicates that αS normally exists in cells in a dynamic equilibrium between monomers and tetramers/multimers. We engineered αS mutants incapable of multimerization, leading to excess monomers at vesicle membranes. By EM, such mutants induced prominent vesicle clustering, leading to round cytoplasmic inclusions. Immunogold labeling revealed abundant αS intimately associated with vesicles of varied size. Fluorescence microscopy with marker proteins showed that the αS-associated vesicles were of diverse endocytic and secretory origin. An αS '3K' mutant (E35K + E46K + E61K) that amplifies the PD/DLB-causing E46K mutation induced αS-rich vesicle clusters resembling the vesicle-rich areas of Lewy bodies, supporting pathogenic relevance. Mechanistically, E46K can increase αS vesicle binding via membrane-induced amphipathic helix formation, and '3K' further enhances this effect. Another engineered αS variant added hydrophobicity to the hydrophobic half of αS helices, thereby stabilizing αS-membrane interactions. Importantly, substituting charged for uncharged residues within the hydrophobic half of the stabilized helix not only reversed the strong membrane interaction of the multimer-abolishing αS variant but also restored multimerization and prevented the aberrant vesicle interactions. Thus, reversible αS amphipathic helix formation and dynamic multimerization regulate a normal function of αS at vesicles, and abrogating multimers has pathogenic consequences.

Validation of Previous Spirometric Reference Equations and New Equations.

BACKGROUND: Pulmonary functions are interpreted using predicted values from reference equations that vary with ethnicity, gender, age, height, and weight. The universally used Choi's reference equations are not validated for Korean populations, and the purpose of this study was to validate them and develop new reference equations. METHODS: Subjects with normal spirometry and chest radiographs, no co-morbidities, and non-smokers, from the Korean National Health and National Examination Survey (KNHANES)-VI were enrolled (n = 117). Intraclass correlation coefficient (ICC) was assessed for reliability of reference equations. New reference equations were developed using linear regression analysis. Differences between observed and predicted values were assessed to compare the reference equations from Choi's, Global Lung Function Initiative 2012, KNHANES-IV, and newly developed equations. RESULTS: The ICC of Choi's reference equations was 0.854 (P < 0.001). The new reference equations for men were: forced vital capacity (FVC) (L) = - 4.38775 - 0.01184 × age + 0.05547 × height, forced expiratory volume - 1 second (FEV1) (L) = - 2.40147 - 0.02134 × age + 0.04103 × height; and for women: FVC (L) = - 3.09063 + 0.003904 × age + 0.038694 × height; FEV1 (L) = - 1.32933 - 0.00872 × age + 0.02762 × height. The differences between the predicted and observed means were largest in Choi's equations, but lowest in the new equations with highest goodness of fit. CONCLUSION: Because Choi's reference equations presented larger differences from the observed values, despite reliability, and the new reference equations showed better goodness of fit, we suggest the latter for Korean populations.