Cycloheximide (CHX) Chase Assay to Examine Protein Half-life.

Cycloheximide (CHX) is a small molecule derived from Streptomyces griseus that acts as fungicide. As a ribosome inhibitor, CHX can restrict the translation elongation of eukaryotic protein synthesis. Once protein synthesis is inhibited by CHX, the level of intracellular proteins decreases by degradation through the proteasome or lysosome system. Thus, the CHX chase assay is widely recognized and used to observe intracellular protein degradation and to determine the half-life of a given protein in eukaryotes. Here, we present a complete experimental procedure of the CHX chase assay. Graphical overview.

Relationship between left-behind status and cognitive function in older Chinese adults: a prospective 3-year cohort study.

Background: Due to the inaccuracy of the traditional geographical distance-based definition of left-behind status, data on the negative effect of left-behind status on cognitive function among older adults are controversial. Aims: This study examined the cross-sectional and longitudinal associations of left-behind status with cognitive function in older Chinese adults. The left-behind status definition was based on the frequency of face-to-face parent-child meetings. Methods: Data from a nationally representative sample of 8 682 older adults (60+ years) in 2015 (5 658 left behind and 3 024 non-left behind), of which 6 933 completed the follow-up in 2018, were obtained from the China Health and Retirement Longitudinal Study. Left-behind older adults were broadly defined as those aged 60+ years who had living adult children and saw their children less than once per month. The cognitive function was assessed with a composite cognitive test with higher total scores indicating better cognitive function. Results: Left-behind older adults had significantly lower cognitive test scores than non-left-behind older adults in both 2015 (11.1 (6.0) vs 13.2 (5.9), t=15.863, p<0.001) and 2018 (10.0 (6.6) vs 12.4 (6.7), t=14.177, p<0.001). After adjusting for demographic factors, lifestyle factors, chronic medical conditions and the baseline cognitive test score (in the longitudinal analysis only), on average, the cognitive test score of left-behind older adults was 0.628 lower than their non-left-behind counterparts in 2015 (t=5.689, p<0.001). This difference in cognitive test scores attenuated to 0.322 but remained significant in 2018 (t=2.733, p=0.006). Conclusions: Left-behind older Chinese adults have a higher risk of poor cognitive function and cognitive decline than their non-left-behind counterparts. Specific efforts targeting left-behind older adults, such as encouraging adult children to visit their parents more regularly, are warranted to maintain or delay the progression of cognitive decline.

E3 ubiquitin ligase MID1 ubiquitinates and degrades type-I interferon receptor 2.

Type I interferon (IFN-I) is a common biological molecule used for the treatment of viral diseases. However, the clinical antiviral efficacy of IFN-I needs to be greatly improved. In this study, IFN-I receptor 2 (IFNAR2) was revealed to undergo degradation at the protein level in cells treated with IFN-I for long periods of time. Further studies found a physical interaction between the E3 ubiquitin ligase midline-1 (MID1) and IFNAR2. As a consequence, MID1 induced both K48- and K63-linked polyubiquitination of IFNAR2, which promoted IFNAR2 protein degradation in a lysosome-dependent manner. Conversely, knockdown of MID1 largely restricted IFN-I-induced degradation of IFNAR2. Importantly, MID1 regulated the strength of IFN-I signalling and IFN-I-induced antiviral activity. These findings reveal a regulatory mechanism of IFNAR2 ubiquitination and protein stability in IFN-I signalling, which could provide a potential target for improving the antiviral efficacy of IFN-I.

Depression compromises antiviral innate immunity via the AVP-AHI1-Tyk2 axis.

Depression is a serious public-health issue. Recent reports have suggested higher susceptibility to viral infections in depressive patients. However, how depression affects antiviral innate immune signaling remains unknown. Here, we revealed a reduction in expression of Abelson helper integration site 1 (AHI1) in the peripheral blood mononuclear cells (PBMCs) and macrophages from the patients with major depressive disorder (MDD), which leads to attenuated antiviral immune response. We found that depression-related arginine vasopressin (AVP) induces reduction of AHI1 in macrophages. Further studies demonstrated that AHI1 is a critical stabilizer of basal type-I-interferon (IFN-I) signaling. Mechanistically, AHI1 recruits OTUD1 to deubiquitinate and stabilize Tyk2, while AHI1 reduction downregulates Tyk2 and IFN-I signaling activity in macrophages from both MDD patients and depression model mice. Interestingly, we identified a clinical analgesic meptazinol that effectively stimulates AHI1 expression, thus enhancing IFN-I antiviral defense in depression model mice. Our study promotes the understanding of the signaling mechanisms of depression-mediated antiviral immune dysfunction, and reveals meptazinol as an enhancer of antiviral innate immunity in depressive patients.

Targeting PARP11 to avert immunosuppression and improve CAR T therapy in solid tumors.

Evasion of antitumor immunity and resistance to therapies in solid tumors are aided by an immunosuppressive tumor microenvironment (TME). We found that TME factors, such as regulatory T cells and adenosine, downregulated type I interferon receptor IFNAR1 on CD8+ cytotoxic T lymphocytes (CTLs). These events relied upon poly-ADP ribose polymerase-11 (PARP11), which was induced in intratumoral CTLs and acted as a key regulator of the immunosuppressive TME. Ablation of PARP11 prevented loss of IFNAR1, increased CTL tumoricidal activity and inhibited tumor growth in an IFNAR1-dependent manner. Accordingly, genetic or pharmacologic inactivation of PARP11 augmented the therapeutic benefits of chimeric antigen receptor T cells. Chimeric antigen receptor CTLs engineered to inactivate PARP11 demonstrated a superior efficacy against solid tumors. These findings highlight the role of PARP11 in the immunosuppressive TME and provide a proof of principle for targeting this pathway to optimize immune therapies.

High salt activates p97 to reduce host antiviral immunity by restricting Viperin induction.

High-salt diets have recently been implicated in hypertension, cardiovascular disease, and autoimmune disease. However, whether and how dietary salt affects host antiviral response remain elusive. Here, we report that high salt induces an instant reduction in host antiviral immunity, although this effect is compromised during a long-term high-salt diet. Further studies reveal that high salt stimulates the acetylation at Lys663 of p97, which promotes the recruitment of ubiquitinated proteins for proteasome-dependent degradation. p97-mediated degradation of the deubiquitinase USP33 results in a deficiency of Viperin protein expression during viral infection, which substantially attenuates host antiviral ability. Importantly, switching to a low-salt diet during viral infection significantly enhances Viperin expression and improves host antiviral ability. These findings uncover dietary salt-induced regulation of ubiquitinated cellular proteins and host antiviral immunity, and could offer insight into the daily consumption of salt-containing diets during virus epidemics.

HSV-1-encoded ICP0 degrades the host deubiquitinase BRCC36 to antagonize interferon antiviral response.

Type I interferon (IFN-I) plays pivotal roles in defense against viral infection. HSV-1 has evolved multiple strategies to evade IFN-I antiviral response. In this study, we revealed a new mechanism that HSV-1-encoded ICP0 regulates the host deubiquitinase BRCC36 to inhibit IFN-I antiviral response. We found that HSV-1 infection rapidly downregulates BRCC36 proteins at the early stage of infection. Further studies demonstrated that HSV-1-encoded ICP0 induces K48-linked polyubiquitination and degradation of BRCC36. Importantly, HSV-1-induced BRCC36 degradation promotes downmodulation of IFN-I receptor IFNAR1, thus restricting host IFN-I antiviral response to facilitate HSV-1 early infection. These findings uncover a novel immune evasion mechanism exploited by HSV-1 and could provide potential strategies for anti-HSV-1 therapy.

Ubiquitin E3 ligase MID1 inhibits the innate immune response by ubiquitinating IRF3.

Interferon regulatory factor 3 (IRF3) is a critical transcription factor for inducing production of type I interferons (IFN-I) and regulating host antiviral response. Although IRF3 activation during viral infection has been extensively studied, the inhibitory regulation of IRF3 remains largely unexplored. Here, we revealed that Midline-1 (MID1) is a ubiquitin E3 ligase of IRF3 that plays essential roles in regulating the production of IFN-I. We found that MID1 physically interacts with IRF3 and downregulates IRF3 protein levels. Next, we demonstrated that MID1 can induce K48-linked polyubiquitination of IRF3, thus lowing the protein stability of IRF3. Our further studies identified Lys313 as a major ubiquitin acceptor lysine of IRF3 induced by MID1. Finally, MID1-mediated ubiquitination and degradation of IRF3 restrict IFN-I production and cellular antiviral response. This study uncovers a role of MID1 in regulating innate antiviral immunity and may provide a potential target for enhancing host antiviral activity.

Ubiquitin E3 Ligase c-Cbl Is a Host Negative Regulator of Nef Protein of HIV-1.

Nef is an accessory protein encoded by human immunodeficiency virus type-1 (HIV-1) and plays important roles in regulating HIV-1 infection and viral replication. Interestingly, HIV-1 Nef can promote degradation of numerous host proteins to disrupt cellular antiviral immune response. However, how HIV-1 Nef is degraded by host factors remains largely unexplored. Here, we identified c-Cbl as a host ubiquitin E3 ligase of HIV-1 Nef. We found that c-Cbl interacts with Nef and reduces protein levels of HIV-1 Nef. Further studies demonstrated that c-Cbl promoted Lys48-linked polyubiquitination of HIV-1 Nef, thus attenuating protein stability of HIV-1 Nef. Importantly, cellular c-Cbl ubiquitinated and degraded Nef proteins produced by HIV-1 NL4-3 virions, and ultimately attenuated HIV-1 virulence for infection of THP1 cells. This study reveals a ubiquitination and proteasome-dependent degradation mechanism of HIV-1 Nef protein, and could provide potential strategies for fighting against HIV-1.

Exchange-biased hybrid γ-Fe2O3/NiO core-shell nanostructures: three-step synthesis, microstructure, and magnetic properties.

A two-step solvothermal method combining a calcination process was conducted to synthesize γ-Fe2O3/NiO core-shell nanostructures with controlled microstructure. The formation mechanism of this binary system has been discussed, and the influence of microstructures on magnetic properties has been analyzed in detail. Microstructural characterizations reveal that the NiO shells consisted of many irregular nanosheets with disordered orientations and monocrystalline structures, packed on the surface of the γ-Fe2O3 microspheres. Both the grain size and NiO content of nanostructures increase with the increasing calcination temperature from 300 °C to 400 °C, accompanied by an enhancement of the compactness of NiO shells. Magnetic studies indicate that their magnetic properties are determined by four factors: the size effect, NiO phase content, interface microstructure, i.e. contact mode, area, roughness and compactness, and FM-AFM (where FM and AFM denote the ferromagnetic γ-Fe2O3 and the antiferromagnetic NiO components, respectively) coupling effect. At 5 K, the γ-Fe2O3/NiO core-shell nanostructures display certain exchange bias (HE = 60 Oe) and enhanced coercivity (HC = 213 Oe).

A coordinated PCP-Cardiologist Telemedicine Model (PCTM) in China's community hypertension care: study protocol for a randomized controlled trial.

BACKGROUND: Hypertension is a major risk factor for cardiovascular disease, and its control rate has remained low worldwide. Studies have found that telemonitoring blood pressure (BP) helped control hypertension in randomized controlled trials. However, little is known about its effect in a structured primary care model in which primary care physicians (PCPs) are partnering with cardiology specialists in electronic healthcare data sharing and medical interventions. This study aims to identify the effects of a coordinated PCP-cardiologist model that applies telemedicine tools to facilitate community hypertension control in China. METHODS/DESIGN: Patients with hypertension receiving care at four community healthcare centers that are academically affiliated to Shanghai Chest Hospital, Shanghai JiaoTong University are eligible if they have had uncontrolled BP in the previous 3 months and access to mobile Internet. Study subjects are randomly assigned to three interventional groups: (1) usual care; (2) home-based BP telemonitor with embedded Global System for Mobile Communications (GSM) module and unlimited data plan, an app to access personal healthcare record and receive personalized lifestyle coaching contents, and proficiency training of their use; or (3) this plus coordinated PCP-cardiologist care in which PCPs and cardiologists share data via a secure CareLinker website to determine interventional approaches. The primary outcome is mean change in systolic blood pressure over a 12-month period. Secondary outcomes are changes of diastolic blood pressure, HbA1C, blood lipids, and medication adherence measured by the eight-item Morisky Medication Adherence Scale. DISCUSSION: This study will determine whether a coordinated PCP-Cardiologist Telemedicine Model that incorporates the latest telemedicine technologies will improve hypertension care. Success of the model would help streamline the present community healthcare processes and impact a greater number of patients with uncontrolled hypertension. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02919033 . Registered on 23 September 2016.

Status of HBsAg seroprevalence in 15 million rural couples in China: a cross-sectional study.

A cross-sectional analysis of prevalence of hepatitis B virus infection (HBV) among rural couples was conducted between 2010 and 2014. Serologic HBV markers, including hepatitis B surface antigen (HBsAg) and e antigen (HBeAg), were tested. Primary outcome of interest comprised HBsAg positivity in couples (both positive: F+M+, only wife positive: F+M-, only husband positive: F-M+), and secondary outcome consisted of prevalence and risk factors of HBsAg positivity among husbands or wives. Of 14,816,300 couples included, 0.7% were F+M+; 6.3% were F-M+; 4.4% were F+M-, resulting in the overall seroprevalence of 11.4%. Individually, 6.1% were HBsAg positive with a higher rate seen in husbands (7.0%) than in wives (5.2%). Wife's HBeAg(+)/HBsAg (+) (AOR = 2.61), HBeAg(-)/HBsAg (+) (AOR = 2.23), positivity of syphilis (AOR = 1.50), living in a high-risk region (AOR = 1.46) were significantly predictors of HBsAg positivity in husbands. Prevalence and predictors of HBsAg positivity in wives had similar results. Our data show a high burden and discordant pattern of HBV infection in rural couples, and partner's double positivity of HBeAg and HBsAg was the most significant factor of HBV infection in couples. A comprehensive strategy that emphasizes vaccination and education is needed.

[Local Regression Algorithm Based on Net Analyte Signal and Its Application in Near Infrared Spectral Analysis].

Abstract To overcome the problems of significant difference among samples and nonlinearity between the property and spectra of samples in spectral quantitative analysis, a local regression algorithm is proposed in this paper. In this algorithm, net signal analysis method(NAS) was firstly used to obtain the net analyte signal of the calibration samples and unknown samples, then the Euclidean distance between net analyte signal of the sample and net analyte signal of calibration samples was calculated and utilized as similarity index. According to the defined similarity index, the local calibration sets were individually selected for each unknown sample. Finally, a local PLS regression model was built on each local calibration sets for each unknown sample. The proposed method was applied to a set of near infrared spectra of meat samples. The results demonstrate that the prediction precision and model complexity of the proposed method are superior to global PLS regression method and conventional local regression algorithm based on spectral Euclidean distance.

Effects of tripterygium glycosides on restenosis following endovascular treatment.

The mechanism and associated factors of restenosis following intravascular stent implantation remain to be elucidated. The present two­part experimental and clinical study aimed to investigate the effects of tripterygium glycosides on in­stent restenosis subsequent to intra­arterial therapy. Following endovascular stent implantation in rabbit iliac arteries, post­stent outcomes were evaluated in cyclosporine groups, low­dose and high­dose tripterygium glycosides groups and controls. Post­operative angiography indicated that vessel diameters were similar between groups; however, at 28 days after receiving the therapeutic agents, vessels of the cyclosporine and tripterygium glycosides groups were significantly larger than those of the controls. Furthermore, three groups of patients had comparable baseline levels of interleukin (IL)­10, IL­18 and C­reactive protein, and intima­media thickness. However, 1 month after stent implantation, levels of IL­10 and IL­18 were markedly reduced in the high­ and low­dose tripterygium glycosides groups compared with controls. At 6 months after surgery, the stent patency rate in patients with bare stents was significantly lower than in patients receiving tripterygium glycosides (P≤0.009). In addition, the ankle­brachial index was also higher than in those without tripterygium glycosides (P<0.001). Results of the experimental and clinical studies suggest that tripterygium glycosides may inhibit and possibly aid in the prevention of in­stent restenosis formation following endovascular treatment of lower­extremity artery disease.

[An Improved ELM Algorithm for Near Infrared Spectral Quantitative Analysis].

Extreme learning machine (ELM) has been applied in near infrared spectral analysis as a novel chemometric method which attracted the attentions of various researchers. However, the dimension of spectral data is usually very high while more hidden nodes should be incorporated in original ELM model for spectral data. Thus the problems of high dimension and high colinearity in the output matrix of hidden layer of ELM model are inevitable. The solutions obtained with the existing Moore-Penrose generalized inverse can be ill-conditional due to the high dimension and high colinearity in the hidden layer output matrix. This study aims to propose an improved ELM to build spectral regression model. The proposed method firstly uses extreme learning machine (ELM) to relate spectral variables to response variable; then the output of each hidden node are treated as new variables; VIP-SPLS ( improved stacked PLS based on variable importance in the projection) proposed by our group recently is used to build the regression model between those new variables and the response variable. In this paper, this method is called as improved ELM (iELM). VIP-SPLS model can fully utilize the output information of each hidden node and can effectively solve the problems of high dimension and high colineariy. At the same time, VIP-SPLS also has the advantage of model ensemble. Therefore, the performance of ELM model used for spectral data can be improved if the VIP-SPLS is incorporated to relate the hidden layer output matrix and response variable. The proposed method is applied to a commonly used benchmark NIR spectral data for evaluation. The results demonstrate that the precision improvement of iELM model is 29.06% to PLS model and 27.47% to original ELM model, respectively.

Melanocortin-4 receptor agonists alleviate intestinal dysfunction in secondary intra-abdominal hypertension rat model.

BACKGROUND: Intra-abdominal hypertension (IAH) is a potentially life-threatening disease. Melanocortin-4 (MC4) receptor activation exhibits life-saving properties. The aim of the present study was to examine whether treatment with the MC4 receptor agonist RO27-3225 ameliorates intestinal injury in IAH rats. METHODS: A total of 72 male Sprague-Dawley rats were randomized into six groups. Group 1 was the sham group. Group 2, the sham + RO group, received RO27-3225 (180 µg/kg, intraperitoneally). IAH was induced in group 3, the IAH group, by blood draw (mean arterial pressure = 30 mm Hg for 90 min) followed by shed blood and/or Ringer solution reinfusion. Intra-abdominal pressure was increased to 20 mm Hg by injecting air into the peritoneal cavity. Group 4, the RO group, was administered RO27-3225 at 5 min after blood draw. Groups 5 and 6 were the chlorisondamine (Chl) and HS024 groups, in which the rats were pretreated with the nicotinic acetylcholine receptor antagonist Chl or selective MC4 receptor antagonist (HS024), respectively, at 2 min before RO27-3225 was administered. RESULTS: RO27-3225 restored mean arterial pressure, reduced tumor necrosis factor-α, and interleukin-1ß messenger RNA expression increased by IAH, alleviated histologic damage, and improved superoxide dismutase activity in the intestine. Compared with the IAH group, the levels of intestinal fatty acid-binding protein, intestinal edema and intestinal permeability were lower in the RO group. Furthermore, the RO27-3225 treatment increased the expression of Rho-associated coiled-coil-containing protein kinase 1 and phosphorylated myosin light chain. Chl and HS024 abrogated the protective effects of RO27-3225. CONCLUSIONS: These data indicate that the MC4 receptor agonist counteracts the intestinal inflammatory response, ameliorating intestinal injury in experimental secondary IAH by MC4 receptor-triggered activation of the cholinergic anti-inflammatory pathway. It may represent a promising strategy for the treatment of IAH in the future.

Melanocortin MC4 receptor agonists alleviate brain damage in abdominal compartment syndrome in the rat.

Intra-abdominal hypertension (IAH) is accompanied by high morbidity and mortality in surgical departments and ICUs. However, its specific pathophysiology is unclear. IAH not only leads to intra-abdominal tissue damage but also causes dysfunction in distal organs, such as the brain. In this study, we explore the protective effects of melanocortin 4 receptor agonists in IAH-induced brain injury. The IAH rat models were induced by hemorrhagic shock/resuscitation (with the mean arterial pressure (MAP) maintained at 30 mm Hg for 90 min followed by the reinfusion of the withdrawn blood with lactated Ringer's solution). Then, air was injected into the peritoneal cavity of the rats to maintain an intra-abdominal pressure of 20 mm Hg for 4 h. The effects of the melanocortin 4 receptor agonist RO27-3225 in alleviating the rats' IAH brain injuries were observed, which indicated that RO27-3225 could reduce brain edema, the expressions of the IL-1ß and TNF-α inflammatory cytokines, the blood-brain barrier's permeability and the aquaporin4 (AQP4) and matrix metalloproteinase 9 (MMP9) levels. Moreover, the nicotinic acetylcholine receptor antagonist chlorisondamine and the selective melanocortin 4 receptor antagonist HS024 can negate the protective effects of the RO27-3225. The MC4R agonist can effectively reduce the intracerebral proinflammatory cytokine gene expression and alleviate the brain injury caused by blood-brain barrier damage following IAH.

Prevention of pulmonary embolisms associated with vena cava filter implantation.

OBJECTIVE: To investigate the prevention of pulmonary embolism (PE) by the implantation of inferior vena cava filters (IVCFs). METHODS: Data of 1058 patients treated for lower extremity deep vein thrombosis (DVT) between January 2005 and January 2012 were analyzed retrospectively and divided into those with and without PE. RESULTS: Of the 1058 patients, 34 had PEs (3.2%) and 1024 did not. Multivariable analyses showed that PEs were less likely to occur in patients with IVCFs than in those without IVCFs (odd ratio [OR] = 0.028, P < 0.001), and were more likely to occur in patients with vena cava thrombosis than in those without vena cava thrombosis (OR = 19.094, P < 0.001). Analyses stratified by DVT site showed that vena cava thrombosis was the only risk factor of PE for patients with a left DVT (crude OR = 12.814, P < 0.001), and IVCF implantation was the only protective factor for PE for patients with a right or bilateral DVT (crude OR = 0.028, P = 0.001). IVCF patency rate for follow-up was 98.7% with no filter migration, declination, or failure of expansion. CONCLUSIONS: IVCFs can reduce the occurrence of PEs in patients with DVTs.

[Discrimination of types of polyacrylamide based on near infrared spectroscopy coupled with least square support vector machine].

In this paper, a novel discriminant methodology based on near infrared spectroscopic analysis technique and least square support vector machine was proposed for rapid and nondestructive discrimination of different types of Polyacrylamide. The diffuse reflectance spectra of samples of Non-ionic Polyacrylamide, Anionic Polyacrylamide and Cationic Polyacrylamide were measured. Then principal component analysis method was applied to reduce the dimension of the spectral data and extract of the principal compnents. The first three principal components were used for cluster analysis of the three different types of Polyacrylamide. Then those principal components were also used as inputs of least square support vector machine model. The optimization of the parameters and the number of principal components used as inputs of least square support vector machine model was performed through cross validation based on grid search. 60 samples of each type of Polyacrylamide were collected. Thus a total of 180 samples were obtained. 135 samples, 45 samples for each type of Polyacrylamide, were randomly split into a training set to build calibration model and the rest 45 samples were used as test set to evaluate the performance of the developed model. In addition, 5 Cationic Polyacrylamide samples and 5 Anionic Polyacrylamide samples adulterated with different proportion of Non-ionic Polyacrylamide were also prepared to show the feasibilty of the proposed method to discriminate the adulterated Polyacrylamide samples. The prediction error threshold for each type of Polyacrylamide was determined by F statistical significance test method based on the prediction error of the training set of corresponding type of Polyacrylamide in cross validation. The discrimination accuracy of the built model was 100% for prediction of the test set. The prediction of the model for the 10 mixing samples was also presented, and all mixing samples were accurately discriminated as adulterated samples. The overall results demonstrate that the discrimination method proposed in the present paper can rapidly and nondestructively discriminate the different types of Polyacrylamide and the adulterated Polyacrylamide samples, and offered a new approach to discriminate the types of Polyacrylamide.