Terminal Peptide Research Articles

Liquid Crystal Behavior of Uniform Short Rods Made from Computationally Designed Parallel Coiled Coil Building Blocks.

Parallel, homotetrameric coiled coils were computationally designed using 29 amino acid peptides. These parallel coiled coils, called "bundlemers", have C2 symmetry, with all N-termini displayed from one end of the nanoparticle and all C-termini from the opposite end. This anisotropic display of the peptide termini allowed for the functionalization of two sets of nanoparticles with either maleimide or thiol functionality at the N-terminal region of the constituent peptides. The thiol-Michael conjugation reaction between the N-terminal end of complementary bundlemer nanoparticles formed monodisperse, rigid bundlemer dimer, called "dibundlemer", rods. The constituent, individual bundlemer nanoparticles were characterized with small-angle X-ray scattering (SAXS), Förster resonance energy transfer (FRET), and circular dichroism (CD) spectroscopy to confirm the parallel assembly of the coiled coils, consistent with the computational design. The dibundlemer rods were characterized with SAXS to reveal the uniform dibundlemer nature of the rods. Optical birefringence is observed in concentrated samples of the rods, with polarized optical microscopy (POM) revealing a nematic liquid crystalline behavior.

The in-hospital administration of sacubitril/valsartan in acute myocardial infarction: A meta-analysis.

There is a need to address the evidence gap regarding the in-hospital administration of sacubitril/valsartan in acute myocardial infarction patients. After searching MEDLINE, Google Scholars and Scopus, a random-effects meta-analysis of randomized controlled trials comparing the in-hospital administration of the angiotensin receptor-neprilysin inhibitors (ARNis) versus the standard therapy in patients with reduced heart failure due to myocardial infarction was performed. The primary outcome was major adverse cardiovascular events. All-cause mortality, cardiac death, rehospitalization for heart failure, non-fatal myocardial infarction (MI), changes in left ventricular ejection fraction, left ventricular volumes, N terminal pro brain natriuretic peptide and adverse events were the secondary endpoints. Nine studies (eight randomized controlled trials and one echo-substudy) with a total 6597 individuals (angiotensin-converting enzyme inhibitor/angiotensin receptor blocker: 3300 patients vs. ARNis: 3297 patients) were included for quantitative analysis. Median follow-up was 6months. Patients receiving an in-hospital coadministration of ARNi had a lower risk of major cardiovascular event [odds ratio (OR) 0.45, 95% confidence interval (CI) 0.32-0.63, P<0.0001] and lower rate of repeat rehospitalization for heart failure (OR 0.40, 95% CI 0.26-0.62, P<0.0001), compared with a standard regimen. Additionally, left ventricle volumes were significantly lower in the ARNi group [left ventricular end-diastolic volume, mean difference (MD) 11.48mL, 95% CI 6.10-16.85, P<0.0001; left ventricular end-systolic volume, MD 7.09mL, 95% CI 2.89-11.29, P=0.0009] with a significant change in left ventricular ejection fraction (MD 3.07, 95% CI 1.61-4.53, P<0.0001), compared with standard therapy. No significant differences were observed in terms of cardiac death, all cause of mortality, non-fatal myocardial infarction and N terminal pro brain natriuretic peptide. Higher rates of iatrogenic hypotensive events were observed in the ARNi group compared with the standard therapy (OR 1.42, 95% CI 1.26-1.60, P value<0.00001). In patients with acute myocardial infarction related heart failure, the in-hospital administration of ARNis was associated with a reduced risk of major cardiovascular events and re-hospitalization for heart failure, as well as cardiac remodelling, but higher rates of hypotensive events compared with standard therapy.

A Clickase-Mediated Immunoassay Based on Nanopore and Bionic Signal Labels for Ultrasensitive, Portable, and On-Site Detection of Ricin.

It is of particular importance to develop an effective method that possesses several merits simultaneously of rapid, ultrasensitive, portable, and on-site detection potential for food safety detection. Herein, we propose a clickase-mediated immunoassay based on nanopore and bionic signal labels for the detection of ricin. The introduction of Cu/Cys clickase and nanopore simultaneously effectively addressed the inherent limitations of natural enzymes and colorimetric signal output, respectively. Using this method, bionic signal labels can be easily formed through DNA and Gram-positive bacterial cell wall terminal peptide fragments (labeled by alkynyl and azide, respectively) and vancomycin. Translocation of the D-P@vancomycin through the nanopore generated highly specific oscillation current traces. This method showed a great on-site detection potential and superior analytical performance owing to the combination of the specificity of antibodies, high CuAAC click reaction catalytic efficiency of clickase, ultrasensitivity of the nanopore, and high signal resolution of D-P@vancomycin. Moreover, the practical applicability of the established method was also verified, achieving a limit of detection (LOD) down to 200.9 ag/mL with a wide linear relationship under the optimized conditions. In conclusion, this method is promising for rapid, portable, ultrasensitive, and on-site food safety detection.

Two-way Dispatched function in Sonic hedgehog shedding and transfer to high-density lipoproteins.

The Sonic hedgehog (Shh) signaling pathway controls embryonic development and tissue homeostasis after birth. This requires regulated solubilization of dual-lipidated, firmly plasma membrane-associated Shh precursors from producing cells. Although it is firmly established that the resistance-nodulation-division transporter Dispatched (Disp) drives this process, it is less clear how lipidated Shh solubilization from the plasma membrane is achieved. We have previously shown that Disp promotes proteolytic solubilization of Shh from its lipidated terminal peptide anchors. This process, termed shedding, converts tightly membrane-associated hydrophobic Shh precursors into delipidated soluble proteins. We show here that Disp-mediated Shh shedding is modulated by a serum factor that we identify as high-density lipoprotein (HDL). In addition to serving as a soluble sink for free membrane cholesterol, HDLs also accept the cholesterol-modified Shh peptide from Disp. The cholesteroylated Shh peptide is necessary and sufficient for Disp-mediated transfer because artificially cholesteroylated mCherry associates with HDL in a Disp-dependent manner, whereas an N-palmitoylated Shh variant lacking C-cholesterol does not. Disp-mediated Shh transfer to HDL is completed by proteolytic processing of the palmitoylated N-terminal membrane anchor. In contrast to dual-processed soluble Shh with moderate bioactivity, HDL-associated N-processed Shh is highly bioactive. We propose that the purpose of generating different soluble forms of Shh from the dual-lipidated precursor is to tune cellular responses in a tissue-type and time-specific manner.

Two-way Dispatched function in Sonic hedgehog shedding and transfer to high-density lipoproteins

The Sonic hedgehog (Shh) signaling pathway controls embryonic development and tissue homeostasis after birth. This requires regulated solubilization of dual-lipidated, firmly plasma membrane-associated Shh precursors from producing cells. Although it is firmly established that the resistance-nodulation-division transporter Dispatched (Disp) drives this process, it is less clear how lipidated Shh solubilization from the plasma membrane is achieved. We have previously shown that Disp promotes proteolytic solubilization of Shh from its lipidated terminal peptide anchors. This process, termed shedding, converts tightly membrane-associated hydrophobic Shh precursors into delipidated soluble proteins. We show here that Disp-mediated Shh shedding is modulated by a serum factor that we identify as high-density lipoprotein (HDL). In addition to serving as a soluble sink for free membrane cholesterol, HDLs also accept the cholesterol-modified Shh peptide from Disp. The cholesteroylated Shh peptide is necessary and sufficient for Disp-mediated transfer because artificially cholesteroylated mCherry associates with HDL in a Disp-dependent manner, whereas an N-palmitoylated Shh variant lacking C-cholesterol does not. Disp-mediated Shh transfer to HDL is completed by proteolytic processing of the palmitoylated N-terminal membrane anchor. In contrast to dual-processed soluble Shh with moderate bioactivity, HDL-associated N-processed Shh is highly bioactive. We propose that the purpose of generating different soluble forms of Shh from the dual-lipidated precursor is to tune cellular responses in a tissue-type and time-specific manner.

The correlation between serum bone metabolism indexes and bone disease and survival in newly diagnosed multiple myeloma patients

ABSTRACT Objective Myeloma-related bone disease (MBD) is one of the most common complications of multiple myeloma (MM). This study aims to investigate the correlation between serum bone metabolism indexes (BMIs), the clinical characteristics and prognosis of newly diagnosed MM (NDMM) patients. Methods: The serum BMIs of 148 patients with NDMM in a single hematological disease treatment center from April 2014 to December 2019 were analyzed retrospectively, including type I collagen amino terminal elongation peptide (PINP), β-C-terminal telopeptide of type I collagen (β-CTX) and N-terminal osteocalcin (N-MID). Other clinical indexes were simultaneously collected and the degree of bone damage in patients was evaluated. We explored the effect of serum BMIs on the prognosis and identified independent prognostic factors. Another 77 NDMM patients from April 2018 to February 2021 served as the validation cohort. Results: The area under the curve (AUC) predicted by β-C-terminal telopeptide of type I collagen (β-CTX), type I collagen amino terminal elongation peptide (PINP), and N-terminal osteocalcin (N-MID) for overall survival (OS) were 0.708, 0.613, and 0.538, respectively. Patients with high serum levels had shorter OS (p < .001, p = .004, p = .027, respectively). Cox multivariate analysis indicated that serum β- CTX、lactic dehydrogenase、hemoglobin and the degree of bone injury were independent prognostic factors. A COX regression model was established with a C-index of 0.782 and validated with a C-index of 0.711. Conclusion: The serum BMIs are correlated with the patients’ OS, and β- CTX can be an independent prognostic factor.

Biomarkers of COVID-19 short-term worsening: a multiparameter analysis within the prospective multicenter COVIDeF cohort.

During a pandemic like COVID-19, hospital resources are constrained and accurate severity triage of the patients is required. The objective of this study is to estimate the predictive performances of candidate biomarkers for short-term worsening (STW) of COVID-19. Prospective, multicenter (20 hospitals in Paris) cohort study of consecutive COVID-19 patients with systematic biobanking at admission, during the first waves of COVID-19 in France in 2020 (COVIDeF cohort). Consecutive COVID-19 patients were screened for inclusion. They were excluded in presence of severity criteria defined by either an ICU admission, mechanical ventilation (including noninvasive ventilation), acute respiratory distress, or in-hospital death before sampling. Routine blood tests measured during usual care and centralized systematic measurement of creatine kinase, C-reactive protein (CRP), procalcitonin, soluble urokinase plasminogen activator receptor (suPAR), high-sensitive troponin T (TnT-hs), N terminal pro-B natriuretic peptide (NT-proBNP), calprotectin, platelet factor 4, mid-regional pro-adrenomedullin (MR-proADM), and proendothelin were performed. The primary outcome was STW, defined by a severity criteria within 7 days. A backward stepwise logistic regression model and a 'best subset' approach were used to identify independent association, and the area under the receiving operator characteristics (AUROC) was computed. Five hundred and eleven patients were analyzed, of whom 60 (11.7%) experienced STW. Median time to occurrence of a severity criteria was 3 days. At admission, lower values of eosinophils, lymphocytes, platelets, alanine aminotransferase, and higher values of neutrophils, creatinine, urea, CRP, TnT-hs, suPAR, NT-proBNP, calprotectin, procalcitonin, MR-proADM, and proendothelin were predictive of worsening. Stepwise logistic regression identified three biomarkers significantly associated with worsening: CRP [adjusted odds ratio (aOR): 1.10, 95% confidence interval (95% CI): 1.06-1.15 for a 10-unit increase, AUROC: 0.73 (0.66-0.79)], procalcitonin [aOR: 0.42, 95% CI: 0.22-0.81, AUROC: 0.69 (0.64-0.88)], and MR-proADM [aOR: 2.85, 95% CI: 1.74-4.69, AUROC: 0.75 (0.69-0.81)]. These biomarkers outperformed clinical variables except diabetes and cancer comorbidities. In this multicenter prospective study that assessed a large panel of biomarkers for COVID-19 patients, CRP, procalcitonin, and MR-proADM were independently associated with the risk of STW. ClinicalTrials.gov NCT04352348.

КАРДИОМЕТАБОЛИЧЕСКИЙ ПРОФИЛЬ С УЧЕТОМ СТАДИРОВАНИЯ ПО CMDS У ЛИЦ МОЛОДОГО ВОЗРАСТА

Abstract. Introduction. The burden of cardiovascular disease, diabetes mellitus, and the associated mortality remains high. One classification system that predicts the development of cardiovascular events and type 2 diabetes mellitus is Cardiometabolic Disease Staging (CMDS). The study of new cardiometabolic profile parameters is relevant in the context of their association with residual cardiovascular risk. The aim of the study was to evaluate the cardiometabolic profile, including extended parameters, in young adults, while taking into account the CMDS. Materials and Methods. 185 male and female subjects aged 35.0 [30.0–39.0] years were examined. The participants were divided into groups according to the CMDS classification: Stage 0, metabolically healthy; Stage 1 (low risk), one or two risk factors (RFs) other than prediabetes; Stage 2 (intermediate risk), presence of ≥3 risk factors or prediabetes; Stage 3 (high risk), presence of ≥3 risk factors and prediabetes. The study examined visceral adiposity index, visceral fat level, insulin resistance, leptinemia, hyperuricemia, glomerular filtration rate, C–reactive protein, and N–terminal brain natriuretic peptide concentrations. The data were processed in SPSS Statistics 26. Results and Discussion. The cardiometabolic profile demonstrated unfavorable alterations with the progression of CMDS stages. Across the spectrum from CMDS 0 to CMDS 3, we observed a significant rise in the prevalence of abdominal obesity (0% to 100%, p&lt;0,001), body mass index ≥25 kg/m2 (16.2% to 100%, p&lt;0.001), and excess visceral fat level (0% to 23.8%, p&lt;0.001). Simultaneously, the prevalence of hypercholesterolemia demonstrated a significant rise (24.3% to 52.4%, p=0.025), as did elevated low–density lipoprotein cholesterol (32.4% to 76.1%, p=0.014), insulin resistance (2.7% to 66.7%, p&lt;0.001), leptinemia (45.9% to 90.5%, p=0.009), C–reactive protein (2.7% to 57.1%, p&lt;0.001) and hyperuricemia (16.2% to 61.9%, p&lt;0.001). The median values of these parameters also increased. Conclusions. Our data confirm the simultaneous increase in both the quantity and intensity of risk factors, manifestations of adiposopathy associated with increasing residual cardiovascular risk. Our results substantiate the feasibility of using the CMDS classification at the stage of primary prevention of cardiometabolic diseases to identify groups with the most significant metabolism disorders of lipid, carbohydrate and purine metabolism in young adults.

IL-6 and hsCRP predict cardiovascular mortality in patients with heart failure with preserved ejection fraction.

Inflammation accompanies heart failure (HF) and elevated levels of inflammatory biomarkers are linked to new onset of HF. However, whether the prognostic relevance of inflammatory biomarkers is different in HF with reduced (HFrEF) and preserved ejection fraction (HFpEF) is unclear. The aim of the current study is to explore the role of inflammation on the mortality risk in patients with HF. We analysed interleukin-6 and hsCRP levels by ELISA and immunonephelometry, respectively, in HFpEF and HFrEF patients referred for coronary angiography and assessed the prognostic value in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study. HF was present in 1086 patients (N=506 HFpEF; N=580 HFrEF; mean age 65±10years; 28% female). Increasing IL-6 levels were significantly associated with increased CV mortality in HFpEF [1.5 (95% CI: 1.1-2.2), P=0.018] but not HFrEF [HR 1.3 (95% CI: 1.0-1.7), P=0.06] patients. High-sensitive CRP followed a similar pattern but failed to reach statistical significance after full-adjustment (HFpEF: HR 1.4 95%C I: 1.0-2.0; P=0.065; HFrEF HR: 1.0 95% CI: 0.7-1.3; P=0.800). Interaction analysis in patients stratified by IL-6 and N terminal pro brain natriuretic peptide (NT-proBNP) above and below the median revealed a stepwise increase in CV-mortality in HFpEF (P=0.036) but not HFrEF patients (P=0.220). To investigate the relationship between IL-6 and NT-proBNP, we assessed the genetic IL6-Receptor variant p.Asp358Ala (rs2228145) which is linked to impaired IL-6 receptor signalling. Homozygous carriers with HFpEF but not HFrEF exhibited significantly lower NT-pro-BNP levels compared with wildtype carriers (HFpEF 779pg/mL±787 vs. 1180pg/ mL±1532; P=0.008; HFrEF 2289pg/ mL±3439 vs. 2326pg/ mL±3386; P=0.94), raising the hypothesis that IL-6 signalling may play a pathophysiological role in HFpEF. These data suggest a predictive value of elevated IL-6 for CV-mortality in HFpEF but not in HFrEF patients.

Thiol/Disulfide Homeostasis: A New Oxidative Marker in Heart Failure Patients with Preserved Ejection Fraction.

It is suggested that myocardial dysfunction in heart failure patients may result from increased oxidative stress-related membrane changes. Thiol/disulfide homeostasis is a new oxidative stress indicator. The aim of this study was to evaluate serum thiol levels and thiol/disulfide homeostasis in patients with heart failure with preserved ejection fraction (HFpEF). Eighty-four overweight patients who applied to our clinic between November 2016 and February 2018 and diagnosed with hypertension and left ventricule concentric hypertrophy with normal systolic function are included in the study. Forty-two patients who were asymptomatic and had normal N terminal pro-B type natriuretic peptide (NT-proBNP) levels (≤125) were in the control group. Forty-two patients who have cardiac failure symptoms and have high NT-roBNP levels (>125) were in the patient group. Native thiol, total thiol, and disulfide values of the patient group are found to be significantly lower than the control group (P =.001; P <.001; P =.041 respectively). There is a statictically significant negative correlation between native thiol, total thiol values, and NT-proBNP. There is a statictically significant negative correlation between native thiol, total thiol values, and carbohydrate antigen 125 (CA-125) values. As far as we know from literature, this is the first study on HFpEF and thiol/disulfide homeostasis. It is found that native, total thiol, and disulfide values are low in HFpEF patients and that there is a negative correlation between native, total thiol values and NT-proBNP, CA-125 values. It can be said that oxidant/antioxidant balance is impaired in patients with HFpEF and that larger, randomized studies are needed in order to use oxidant/antioxidant balance in diagnosis and treatment of HFpEF.

An ultrasensitive nanozyme-based immunochromatographic platform for quantitative detection of NT-proBNP using V2(Sn0.8Pt0.2)C MAX phase

terminal pro-brain natriuretic peptide (NT-proBNP) has been demonstrated to be as a sensitive and specific biomarker for the heart failure (HF) management, while the development of timely and accurate point-of-care testing methods for frequent quantitative monitoring of NT-proBNP remains challenging. Nanozymes are gaining increasing attention as an alternative to natural enzymes for colorimetric lateral flow immunoassay (LFIA). However, the development of nanozymes with high catalytic activity and colorimetric signal amplification still poses challenges. Herein, we develop a novel nanozyme system with peroxidase (POD)-like activity by incorporating Pt into the A layer of V2SnC MAX phase. V2(Sn0.8Pt0.2)C MAX displays enhanced brightness in colorimetric signal and remarkably high peroxidase mimicking activity (2542.9 U mg−1), which contributes to the improvement of LFIA sensitivity through catalytic amplification. Density functional theory (DFT) calculations reveal that the presence of Pt effectively lowers the energy barrier for H2O2 adsorption at the A site in V2SnC. Specifically, V2(Sn0.8Pt0.2)C-immunolabeled LFIA strips were developed for the detection of NT-proBNP, exhibiting an unprecedented limit of detection at 0.0016 ng mL−1, which is remarkably enhanced by 1437-fold compared to conventional Au nanoparticles-based LFIA methods. Furthermore, these LFIA strips also demonstrated excellent performance in detecting human plasma-containing samples with a sensitivity of 0.02 ng mL−1 within a linear detection range of 0.02–71.64 ng mL−1. These findings suggest that V2(Sn0.8Pt0.2)C holds great potential as a signal reporter for the development of highly sensitive LFIA assays aimed at accurately monitoring HF progression and prognosis.

Correlation between serum HDL/LDL and t-PINP /β-CTX and osteoporotic vertebral fractures in elderly women

To explore high density lipoprotein (HDL)/low density lipoprotein (LDL) and total typeⅠcollagen amino terminal extender peptide (t-PINP)/ C-terminal peptide of typeⅠcollagen β special sequence(β-CTX)and risk of osteoporosis vertebral fractures (OPVFs) in elderly women. The clinical data of 446 female OPVFs patients aged above 60 years old from January 2019 to December 2020 were retrospectively analyzed. According to whether or not fracture, patients were divided into non-fracture group (186 patients) and fracture group(260 patients). Univariate analysis was performed to analysis age, body mass index(BMI), N-terminal mioldle molecular fragment of osteocalcin, N-MID OC), t-PINP, β-CTX, 25-hydroxyvitamin D[25-(OH) VitD], blood sugar (Glu), total cholesterol(TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), Ca, P, Mg, urea (UREA), creatinine (Cr) and Cystatin C(CysC), and correlation between OPVFs and the above indexes and lipid, bone metabolism indexes between two groups;Logistic regression was performed to analyze risk factors and stratification relationship between vertebral fracture and HDL/LDL, t-PINP/β-CTX. Logistic regression was used to analyze risk factors and stratification relationship between OPVFs and HDL/LDL, t-PINP/β-CTX. There were no significant difference in age and BMI between non-fracture group and fracture group (P>0.05). Compared with non-fracture group, contents of HDL, t-PINP/β-CTX and HDL/LDL in fracture group were decreased, and contents of β-CTX were increased (P<0.05). OPVFs was positively correlated with β-CTX (r=0.110, P<0.05), and negatively correlated with HDL, HDL/LDL and t-PINP/β-CTX (r=-0.157, -0.175, -0.181, P<0.05). HDL and HDL/LDL were negatively correlated with β-CTX (r=-0.22, -0.12, P<0.05) and t-PINP (r=-0.13, -0.10, P<0.05). 25-(OH) VitD was positively correlated with TC and HDL (r=0.11, 0.18, P<0.05). HDL/LDL was positively correlated with t-PINP/β-CTX(r=0.11, P=0.02). t-PINP/β-CTX[OR=0.998, 95%CI(0.997, 1.000), P<0.05], HDL/LDL[OR=0.228, 95%CI(0.104, 0.499), P<0.01] were risk factors for vertebral fracture. The lower levels between two tristratified indicators, the higher the vertebral fracture rate. The risk of fracture was 2.5 and 2 times higher in the lowest stratum than in the highest stratum, with an adjusted OR was[2.112, 95%CI(1.310, 3.404)] and [2.331, 95%CI(1.453, 3.739)], respectively. Serum low HDL/LDL and t-PINP /β-CTX are independent risk factors for OPVF in elderly women, and have good predictive value for OPVF risk.

Characterization of a methyltransferase for iterative N-methylation at the leucinostatin termini in Purpureocillium lilacinum

N-methyltransferase (NMT)-catalyzed methylation at the termini of nonribosomal peptides (NRPs) has rarely been reported. Here, we discover a fungal NMT LcsG for the iterative terminal N-methylation of a family of NRPs, leucinostatins. Gene deletion results suggest that LcsG is essential for leucinostatins methylation. Results from in vitro assays and HRESI-MS-MS analysis reveal the methylation sites as NH2, NHCH3 and N(CH3)2 in the C-terminus of various leucinostatins. LcsG catalysis yields new lipopeptides, some of which demonstrate effective antibiotic properties against the human pathogen Cryptococcus neoformans and the plant pathogen Phytophthora infestans. Multiple sequence alignments and site-directed mutagenesis of LcsG indicate the presence of a highly conserved SAM-binding pocket, along with two possible active site residues (D368 and D395). Molecular dynamics simulations show that the targeted N can dock between these two residues. Thus, this study suggests a method for increasing the variety of natural bioactivity of NPRs and a possible catalytic mechanism underlying the N-methylation of NRPs.

Calcineurin and CK2 Reciprocally Regulate Synaptic AMPA Receptor Phenotypes via α2δ-1 in Spinal Excitatory Neurons.

Calcineurin inhibitors, such as cyclosporine and tacrolimus (FK506), are commonly used immunosuppressants for preserving transplanted organs and tissues. However, these drugs can cause severe and persistent pain. GluA2-lacking, calcium-permeable AMPA receptors (CP-AMPARs) are implicated in various neurological disorders, including neuropathic pain. It is unclear whether and how constitutive calcineurin, a Ca2+/calmodulin protein phosphatase, controls synaptic CP-AMPARs. In this study, we found that blocking CP-AMPARs with IEM-1460 markedly reduced the amplitude of AMPAR-EPSCs in excitatory neurons expressing vesicular glutamate transporter-2 (VGluT2), but not in inhibitory neurons expressing vesicular GABA transporter, in the spinal cord of FK506-treated male and female mice. FK506 treatment also caused an inward rectification in the current-voltage relationship of AMPAR-EPSCs specifically in VGluT2 neurons. Intrathecal injection of IEM-1460 rapidly alleviated pain hypersensitivity in FK506-treated mice. Furthermore, FK506 treatment substantially increased physical interaction of α2δ-1 with GluA1 and GluA2 in the spinal cord and reduced GluA1/GluA2 heteromers in endoplasmic reticulum-enriched fractions of spinal cords. Correspondingly, inhibiting α2δ-1 with pregabalin, Cacna2d1 genetic knock-out, or disrupting α2δ-1-AMPAR interactions with an α2δ-1 C terminus peptide reversed inward rectification of AMPAR-EPSCs in spinal VGluT2 neurons caused by FK506 treatment. In addition, CK2 inhibition reversed FK506 treatment-induced pain hypersensitivity, α2δ-1 interactions with GluA1 and GluA2, and inward rectification of AMPAR-EPSCs in spinal VGluT2 neurons. Thus, the increased prevalence of synaptic CP-AMPARs in spinal excitatory neurons plays a major role in calcineurin inhibitor-induced pain hypersensitivity. Calcineurin and CK2 antagonistically regulate postsynaptic CP-AMPARs through α2δ-1-mediated GluA1/GluA2 heteromeric assembly in the spinal dorsal horn.

Bone metabolism factors in predicting the risk of osteoporosis fracture in the elderly

ObjectiveOsteoporosis (OS) is a systemic bone disease characterized by low bone mass and bone microstructure damage. This study.MethodsAccording to the T value, 88 elderly fracture patients were grouped as the control group (without OS, 43 cases) and observation group (with T value <-2.5, which could be diagnosed as OS, 45 cases). The content of boney containing protein (BGP), total type 1 collagen amino terminal extender peptide (TPINP), β-Crosslaps (β-CTX), parathyroid hormone (PTH) and insulin-like growth factors-1 (IGF-1) was compared. Multivariate logistic regression was adopted to analyze the correlation between biochemical indexes and the occurrence of senile OS fracture and the related risk factors. The diagnostic value in the elderly was analyzed by receiver operating characteristic (ROC) curve.ResultsThe levels of BGP, TPINP, β-CTX, PTH and IGF-1 were elevated, and the level of IGF-1 was decreased in the observation group compared with the control group (P < 0.05). The elevated content of BGP, TPINP, β-CTX and PTH, and the decreased expression of IGF-1 were influencing factors for OS fractures in the elderly (P < 0.05). The sensitivity and specificity to predict the occurrence of OS fractures in the elderly were 91.70% and 90.50%, respectively. The AUC of combined detection was 0.976 (95% CI: 0.952-1.000), which was memorably higher than single indicator detection (P < 0.05). Among 45 patients, 32 cases had good prognosis and 13 had poor prognosis. In comparison with the good prognosis group, the content of BGP, TPINP, β-CTX and PTH were sensibly higher, the level of IGF-1 was prominently lower, and the proportion of fracture history was much higher in poor prognosis group (P < 0.05). Fracture history, BGP, TPINP, β-CTX, PTH and IGF-1 were independent risk factors for poor prognosis of elderly OS fractures (P < 0.05).ConclusionBone metabolism factors were associated with poor prognosis of OS in the elderly. The combined detection had higher diagnostic value in calculating the risk of OS fracture in the elderly than single indicator detection.

Helix Formation from Hydrogen Bond Kinetics in Alanine Homopeptides

We present an analysis of α-helix folding in the coarse-grained coordinate of number of formed helical hydrogen bonds (NHBs) for four alanine peptides (ALA)n, with n = 5, 8, 15, and 21 residues. Starting with multi-microsecond all-atom molecular dynamics trajectories in aqueous solution, we represent the system dynamics in a space of between four (for ALA5) and twenty (for ALA21) hydrogen-bonding microstates. In all cases, transitions changing the hydrogen bond count by 1–2 dominate and the coil formation, NHB 1 → 0, is the fastest process. The calculation of global maximum weight paths shows that, when analyzed at a sufficiently long lag time, folding in the NHB coordinate is consecutive, with direct folding, 0 → 3, for ALA5 and bottlenecks at transitions 4 → 6 for ALA8, 0 → 5 for ALA15, and 0 → 9 for ALA21. Further coarse-graining to 2–4 dimensions was performed with the optimal dimensionality reduction method, allowing the identification of crucial folding intermediates and time scales of their formation in ALA8, ALA15, and ALA21. The detailed analysis of hydrogen bonding patterns revealed that folding is initiated preferentially at both peptide termini. The kinetic model was also used to estimate diffusion and friction coefficients for helix propagation. The description of the helix formation process in the hydrogen bonding coordinate NHB was in good general agreement with the experimental data and qualitatively similar to previous kinetic models of higher dimensions based on structural clustering. Use of the low-dimensional hydrogen bonding picture thus provides a different, complementary way of describing the complex and fascinating mechanism of helix formation.

Principles of peptide selection by the transporter associated with antigen processing

Our ability to fight pathogens relies on major histocompatibility complex class I (MHC-I) molecules presenting diverse antigens on the surface of diseased cells. The transporter associated with antigen processing (TAP) transports nearly the entire repertoire of antigenic peptides into the endoplasmic reticulum for MHC-I loading. How TAP transports peptides specific for MHC-I is unclear. In this study, we used cryo-EM to determine a series of structures of human TAP, both in the absence and presence of peptides with various sequences and lengths. The structures revealed that peptides of eight or nine residues in length bind in a similarly extended conformation, despite having little sequence overlap. We also identified two peptide-anchoring pockets on either side of the transmembrane cavity, each engaging one end of a peptide with primarily main chain atoms. Occupation of both pockets results in a global conformational change in TAP, bringing the two halves of the transporter closer together to prime it for isomerization and ATP hydrolysis. Shorter peptides are able to bind to each pocket separately but are not long enough to bridge the cavity to bind to both simultaneously. Mutations that disrupt hydrogen bonds with the N and C termini of peptides almost abolish MHC-I surface expression. Our findings reveal that TAP functions as a molecular caliper that selects peptides according to length rather than sequence, providing antigen diversity for MHC-I presentation.

N terminal pro-brain natriuretic peptide level and benefits of chronic total occlusion revascularization

BackgroundThe management of revascularization of chronic total occlusions (CTOs) remains controversial. Whether specific patients gain survival benefit from CTO revascularization remains unknown. ObjectivesWe investigated whether (i) patients with CTO have higher N terminal pro-brain natriuretic peptide (NT pro-BNP) levels than patients without CTO, (ii) in patients with CTO, NT pro-BNP levels predict adverse events, and (iii) those with elevated levels benefit from revascularization. MethodsIn 392 patients with stable, significant coronary artery disease (CAD) and CTO undergoing coronary angiography, rates of all-cause mortality, cardiovascular death, and a composite (cardiovascular death, myocardial infarction and heart failure hospitalizations) were investigated. Unadjusted and adjusted Cox proportional and Fine and Gray sub-distribution hazard models were performed to determine the association between NT pro-BNP levels and incident event rates in patients with CTO. ResultsNT pro-BNP levels were higher in patients with, compared to those without CTO (median 230.0 vs. 177.7 pg/mL, p ≤0.001). Every doubling of NT pro-BNP level in patients with CTO was associated with a > 25% higher rate of adverse events. 111 (28.5%) patients underwent CTO revascularization. In patients with elevated NT pro-BNP levels (> 125 pg/mL), those who underwent CTO revascularization had substantially lower adverse event rates compared to patients without CTO revascularization (adjusted cardiovascular death hazard ratio 0.29, 95% confidence interval (0.09–0.88). However, in patients with low NT pro-BNP levels (≤ 125 pg/mL), event rates were similar in those with and without CTO revascularization. ConclusionNT pro-BNP levels can help identify individuals who may benefit from CTO revascularization.

The Impact of Terminal Peptide Extensions of Retinal Inosine 5´Monophosphate Dehydrogenase 1 Isoforms on their DNA-binding Activities.

The main structural difference between the mutation-susceptible retinal isoforms of inosine 5´-monophosphate dehydrogenase-1 (IMPDH-1) with the canonical form resides in the C- and N-terminal peptide extensions with unknown structural/functional impacts. In this report, we aimed to experimentally evaluate the functional impact of these extensions on the specific/non-specific single-stranded DNA (ssDNA)-binding activities relative to those of the canonical form. Our in silico findings indicated the possible contribution of the C-terminal segment to the reduced flexibility of the Bateman domain of the enzyme. In addition, the in silico data indicated that the N-terminal tail acts by altering the distance between the tetramers in the concave octamer complex (the native form) of the enzyme. The overall impact of these predicted structural variations became evident, first, through higher Km values with respect to either of the substrates relative to the canonical isoform, as reported previously (Andashti et al. in Mol Cell Biochem 465(1):155-164, 2020). Secondary, the binding of the recombinant mouse retinal isoform IMPDH1 (603) to its specific Rhodopsin target gene was significantly augmented while its binding to non-specific ssDNA was lower than that of the canonical isoform. The DNA-binding activity of the other mouse retinal isoform, IMPDH1(546), to specific and non-specific ssDNA was lower than that of the canonical form most probably due to the in silico predicted rigidity created in the Bateman domain by the C-terminal peptide extension. Furthermore, the DNA binding to the Rhodopsin target gene by each of the IMPDH isoforms influenced in the presence of GTP (Guanosine triphosphate) and ATP (Adenosine triphosphate).

Prediction model for low bone mass mineral density in type 2 diabetes: an observational cross-sectional study.

Considering the prevalence of type 2 diabetes (T2D), osteoporosis should be considered a serious complication. However, an effective tool for the assessment of low bone mass mineral density (BMD) in T2D patients is not currently available. Therefore, the aim of our study was to establish a simple-to-use risk assessment tool by exploring risk factors for low BMD in T2D patients. This study included 436 patients with a low BMD and 381 patients with a normal BMD. Multiple logistic regression analysis was performed to evaluate risk factors for low BMD in T2D patients. A nomogram was then developed from these results. A receiver operating characteristic (ROC) curve, calibration plot, and goodness-of-fit test were used to validate the nomogram. The clinical utility of the nomogram was also assessed. Multivariate logistic regression indicated that age, sex, education, body mass index (BMI), fasting C-peptide, high-density cholesterol (HDL), alkaline phosphatase (ALP), estimated glomerular filtration rate (eGFR), and type I collagen carboxy terminal peptide (S-CTX) were independent predictors for low BMD in T2D patients. The nomogram was developed from these variables using both the unadjusted area under the curve (AUC) and the bootstrap-corrected AUC (0.828). Calibration plots and the goodness-of-fit test demonstrated that the nomogram was well calibrated. The nomogram-illustrated model can be used by clinicians to easily predict the risk of low BMD in T2D patients. Our study also revealed that common factors are independent predictors of low BMD risk. Our results provide a new strategy for the prediction, investigation, and facilitation of low BMD in T2D patients.