Hexavalent Chromium Induces Neurotoxicity by Triggering Mitochondrial Dysfunction and ROS-Mediated Signals.

Hexavalent chromium (Cr (VI)), one of the most detrimental pollutants, has been ubiquitously present in the environment and causes serious toxicity to humans, such as hepatotoxicity, nephrotoxicity, pulmonary toxicity, and cardiotoxicity. However, Cr (VI)-induced neurotoxicity in primary neuron level has not been well explored yet. Herein, potassium dichromate (K2Cr2O7) was employed to examine the neurotoxicity of Cr (VI) in rat primary hippocampal neurons. MTT test was used to examine the neural viability. Mitochondrial dysfunction was assessed by the JC-1 probe and Mito-Tracker probe. DCFH-DA and Mito-SOX Red were utilized to evaluate the oxidative status. Bcl-2 family and MAPKs expression were investigated using Western blotting. The results demonstrated that Cr (VI) treatment dose- and time-dependently inhibited neural viability. Mechanism investigation found that Cr (VI) treatment causes mitochondrial dysfunction by affecting Bcl-2 family expression. Moreover, Cr (VI) treatment also induces intracellular reactive oxygen species (ROS) generation, DNA damage, and MAPKs activation in neurons. However, inhibition of ROS by glutathione (GSH) effectually balanced Bcl-2 family expression, attenuated DNA damage and the MAPKs activation, and eventually improved neural viability neurons. Collectively, these above results above suggest that Cr (VI) causes significant neurotoxicity by triggering mitochondrial dysfunction, ROS-mediated oxidative damage and MAKPs activation.

When will the immune-stimulating antibody conjugates (ISACs) be transferred from bench to bedside?

Immunostimulatory antibody conjugates (ISACs) as a promising new generation of targeted therapeutic antibody-drug conjugates (ADCs), that not only activate innate immunity but also stimulate adaptive immunity, providing a dual therapeutic effect to eliminate tumor cells. However, several ISACs are still in the early stages of clinical development or have already failed. Therefore, it is crucial to design ISACs more effectively to overcome their limitations, including high toxicity, strong immunogenicity, long development time, and poor pharmacokinetics. This review aims to summarize the composition and function of ISACs, incorporating current design considerations and ongoing clinical trials. Additionally, the review delves into the current issues with ISACs and potential solutions, such as adjusting the drug-antibody ratio (DAR) to improve the bioavailability of ISACs. By leveraging the affinity and bioavailability-enhancing properties of bispecific antibodies, the utility between antibodies and immunostimulatory agents can be balanced. Commonly used immunostimulatory agents may induce systemic immune reactions, and BTK (Bruton's tyrosine kinase) inhibitors can regulate immunogenicity. Finally, the concept of grafting ADC's therapeutic principles is simple, but the combination of payload, linker, and targeted functional molecules is not a simple permutation and combination problem. The development of conjugate drugs faces more complex pharmacological and toxicological issues. Standing on the shoulders of ADC, the development and application scenarios of ISAC are endowed with broader space.

MALAT1 Polymorphisms and Lung Cancer Susceptibility in a Chinese Northeast Han Population.

Background: LncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) was competitive endogenous RNA (ceRNA) involved in various molecular processes for metastasis development in lung cancer. Single nucleotide polymorphisms (SNPs) in MALAT1 gene might be predictive markers for lung cancer. In our study, we selected rs619586 and rs3200401 in MALAT1 gene to explore their effects on lung cancer susceptibility. Methods: The case-control study included 444 lung cancer cases and 460 healthy controls. Genotyping was performed by Taqman allelic discrimination method. Logistic regression, Student t-test, and Chi-square test (χ2 ) were used to analyze the data. Results: The findings of the study showed that rs3200401 was significantly associated with the risk of non-small cell lung cancer (NSCLC) and lung squamous cell carcinoma (LUSC). Compared with homozygous CC genotype, CT heterozygous genotype decreased risk of NSCLC (Pa = 0.034) and LUSC (Pa = 0.025). In addition, no statistical association was detected between rs619586 and lung cancer susceptibility. The interactions between genes and cigarette smoking were discovered via crossover analysis. However, there were no remarkable gene-environment interactions in additive and multiplicative model. Conclusion: Rs3200401 in lncRNA MALAT1 was associated with the susceptibility of non-small-cell lung cancer and lung squamous cell carcinoma. The gene-environmental (cigarette smoking) interactions were not notable.

The tumor promoting roles of HSP60 and HIF2α in gastric cancer cells.

The roles of HSP60 and HIF2α in diagnosis, prognosis, and prevention and treatment of various human cancers have been detected. However, the combined roles of HSP60 and HIF2α on the prognosis of patients with gastric cancer remain unclear. In this work, we confirmed that the levels of HSP60 and HIF2α messenger RNA (mRNA) and protein were higher in gastric cancer tissues than that in matched normal tissues by using real-time PCR and Western blot. Furthermore, we confirmed that inhibition of HSP60 or HIF2α could induce apoptosis and inhibit cell mobility. Co-immunoprecipitation (co-IP) was performed to determine the interaction between HSP60 and HIF2α. Lastly, we confirmed that knockdown of HSP60 or HIF2α induced apoptosis in gastric cancer cells is negatively related to the MEK/ERK signaling in vitro. In summary, HSP60 or HIF2α protein expression may be a predictive marker for the prognosis of the patients with gastric cancer. Targeting HSP60 and HIF2α could be a future strategy to improve survival of gastric patients with poor prognosis.

Portulaca oleracea L. polysaccharide alleviates dextran sulfate sodium-induced ulcerative colitis by regulating intestinal homeostasis.

Portulaca oleracea L. (purslane) is a vegetable that contains a variety of active compounds with nutritional properties and has the potential to treat ulcerative colitis (UC). However, the mechanisms underlying the effects of Portulaca oleracea L. polysaccharide (POP) in alleviating UC remain unclear. In this study, we prepared an aqueous extract of purslane and separated a fraction with molecular weight >10 kDa using membrane separation. This fraction was used to isolate POP. The effect of POP on gut microbiota and colon transcriptome in dextran sulfate sodium-induced UC model mice was evaluated. POP treatment reduced inflammation and oxidative stress imbalance in UC mice. In addition, POP improved the intestinal barrier and regulated intestinal homeostasis. Importantly, POP was found to regulate gut microbiota, maintain the levels of retinol and short-chain fatty acids in the gut, promote the proliferation and differentiation of B cells in the colon, and increase the expression of immunoglobulin A. These results provide novel insights into the role of POP in regulating intestinal homeostasis, which should guide further development of POP as a functional food.

A prospective cohort-based artificial intelligence evaluation system for the protective efficacy and immune response of SARS-CoV-2 inactivated vaccines.

BACKGROUND: Novel coronaviruses constitute a significant health threat, prompting the adoption of vaccination as the primary preventive measure. However, current evaluations of immune response and vaccine efficacy are deemed inadequate. OBJECTIVES: The study sought to explore the evolving dynamics of immune response at various vaccination time points and during breakthrough infections. It aimed to elucidate the synergistic effects of epidemiological factors, humoral immunity, and cellular immunity. Additionally, regression curves were used to determine the correlation between the protective efficacy of the vaccine and the stimulated immune response. METHODS: Employing LASSO for high-dimensional data analysis, the study utilised four machine learning algorithms-logistical regression, random forest, LGBM classifier, and AdaBoost classifier-to comprehensively assess the immune response following booster vaccination. RESULTS: Neutralising antibody levels exhibited a rapid surge post-booster, escalating to 102.38 AU/mL at one week and peaking at 298.02 AU/mL at two weeks. Influential factors such as sex, age, disease history, and smoking status significantly impacted post-booster antibody levels. The study further constructed regression curves for neutralising antibodies, non-switched memory B cells, CD4+T cells, and CD8+T cells using LASSO combined with the random forest algorithm. CONCLUSION: The establishment of an artificial intelligence evaluation system emerges as pivotal for predicting breakthrough infection prognosis after the COVID-19 booster vaccination. This research underscores the intricate interplay between various components of immunity and external factors, elucidating key insights to enhance vaccine effectiveness. 3D modelling discerned distinctive interactions between humoral and cellular immunity within prognostic groups (Class 0-2). This underscores the critical role of the synergistic effect of humoral immunity, cellular immunity, and epidemiological factors in determining the protective efficacy of COVID-19 vaccines post-booster administration.

Protective Effects of Different Molecular Weights of Purslane (Portulaca oleracea L.) Aqueous Extract on DSS-Induced Ulcerative Colitis in Mice.

Purslane, a common wild vegetable, contains active substances with various biological functions. However, its effects have been under-investigated in ulcerative colitis (UC). Therefore, this study investigated the therapeutic effects of purslane macromolecular (POEM) and small molecular extracts (POES) on dextran sulfate sodium (DSS)-induced UC in mice. Membrane separation was used to obtain extracts of different molecular weights, and their compositional differences were compared using liquid chromatography-mass spectrometry (LC/MS). POEM contained more proteins and polysaccharides, whereas POES contained more organic acids and alkaloids. These differences in composition were directly responsible for the different degrees of remission of the alleviated UC in model mice. POEM may alleviate UC by regulating the antioxidant capacity and the gut microbiota, whereas the major alleviatory effect of POES was primarily related to the regulation of antioxidant capacity. The POEM and POES effects identified in this study provide a theoretical basis for the development of purslane as a functional food.

Age and seasonal variation and establishment of reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry.

OBJECTIVES: We aimed to establish reference intervals for water-soluble vitamins determined by liquid chromatography tandem mass spectrometry to improve the diagnosis of vitamin deficiency and outcomes of associated conditions. METHODS: In this retrospective analysis of 24 810 specimens, we aimed to examine sex-, age-, and season-related variations in vitamin levels in different groups, set reference-value intervals for vitamin levels, and evaluate these reference values against those recommended by manufacturers. RESULTS: Levels of vitamins B3, B5, B6, B7, and B12 were higher, and those of vitamins B2, B9, and C were lower, in men than in women. There were seasonal variations in levels of vitamins B1, B3, B5, B6, B9, B12, and C. Levels of vitamins B1, B2, B3, B5, B6, B7, B9, and C differed across age groups; vitamin B1 displayed significant differences between ages 0 to 14 years and adults compared with reference change values. The lower limits of vitamins B1 (ages 15-100 y), B2, B3, B7, and C were lower, and that of vitamin B5 was higher, than the recommended reference values. Finally, the upper limits of vitamins B1, B3, B5, B6, and B7 were lower than the recommended values. CONCLUSIONS: For values obtained using liquid chromatography tandem mass spectrometry, the lower limits of reference intervals for vitamins B1 (ages 15-100 y), B2, B3, B7, and C should be lowered, that of vitamin B5 should be raised, and the upper limits of reference intervals for vitamins B1, B3, B5, B6, and B7 should be lowered.

Incorporation of Laboratory Test Biomarkers Into Dual Antiplatelet Therapy Score Improves Prediction of Ischemic and Bleeding Events in Post-percutaneous Coronary Intervention Patients.

This study aimed to examine the performance of the dual antiplatelet therapy (DAPT) score in two retrospective cohorts of post-percutaneous coronary intervention (PCI) patients and to explore whether incorporating additional biomarkers could further improve the predictive power of the DAPT score. In a retrospective derivation cohort of 4,798 PCI patients, the validity of DAPT score for stratifying ischemic/bleeding risks was explored. Then, the association between the baseline status of 54 laboratory test biomarkers and ischemic/bleeding events was revealed while adjusting for the DAPT score. Combinations of individual laboratory test biomarkers that were significantly associated with ischemic/bleeding events were explored to identify the ones that improved discrimination of ischemic and bleeding events when incorporated into DAPT score. Finally, the impact of the combination of biomarkers with DAPT score was validated in an independent retrospective validation cohort of 1,916 PCI patients. Patients with a high DAPT score (DAPT score ≥ 2) had significantly higher risk of ischemic events and significantly lower risk of bleeding than patients with a low DAPT score (DAPT score < 2). Moreover, the addition of aspartate aminotransferase (AST) and red cell distribution width CV (RDW-CV) into the DAPT score further improved discrimination of ischemia and bleeding. Furthermore, the incremental predictive value of AST + RDW-CV maintained with measurements was updated at post-baseline time points. DAPT score successfully stratified the risks of ischemia/bleeding post PCI in the current cohorts. Incorporation of AST + RDW-CV into the DAPT score further improved prediction for both ischemic and bleeding events.

Top-Down Analysis of Small Plasma Proteins Using an LTQ-Orbitrap. Potential for Mass Spectrometry-Based Clinical Assays for Transthyretin and Hemoglobin.

Transthyretin (TTR) amyloidosis and hemoglobinopathies are the archetypes of molecular diseases where point mutation characterization is diagnostically critical. We have developed a Top-down analytical platform for variant and/or modified protein sequencing and are examining the feasibility of using this platform for the analysis of hemoglobin/TTR patient samples and evaluating the potential clinical applications. The platform is based on a commercial high resolution hybrid orbitrap mass spectrometer (LTQ-Orbitrap(™)) with automated sample introduction; automated data analysis is performed by our own software algorithm (BUPID topdown).The analytical strategy consists of iterative data capture, first recording a mass profile of the protein(s). The presence of a variant is revealed by a mass shift consistent with the amino acid substitution. Nozzle-skimmer dissociation (NSD) of the protein(s) yields a wide variety of sequence-defining fragment ions. The fragment ion containing the amino acid substitution or modification can be identified by searching for a peak exhibiting the mass shift observed in the protein mass profile. This fragment ion can then be selected for MS/MS analysis in the ion trap to yield sequence information permitting the identification of the variant. Substantial sequence coverage has been obtained in this manner. This strategy allows for a stepwise MS/MS analysis of the protein structure. The sequence information obtained can be supplemented with whole protein NSD fragmentation and MS/MS analysis of specific protein charge states. The analyses of variant forms of TTR and hemoglobin are presented to illustrate the potential of the method.

Can body mass index, waist circumference, waist-hip ratio and waist-height ratio predict the presence of multiple metabolic risk factors in Chinese subjects?

BACKGROUND: Obesity is associated with metabolic risk factors. Body mass index (BMI), waist circumference, waist-hip ratio (WHR) and waist-height ratio (WHtR) are used to predict the risk of obesity related diseases. However, it has not been examined whether these four indicators can detect the clustering of metabolic risk factors in Chinese subjects. METHODS: There are 772 Chinese subjects in the present study. Metabolic risk factors including high blood pressure, dyslipidemia, and glucose intolerance were identified according to the criteria from WHO. All statistical analyses were performed separately according to sex by using the SPSS 12.0. RESULTS: BMI, waist circumference and WHtR values were all significantly associated with blood pressure, glucose, triglyceride and also with the number of metabolic risk factors in both male and female subjects (all of P < 0.05). According to receiver operating characteristic (ROC) analysis, the area under curve values of BMI, waist circumference and WHtR did not differ in male (0.682 vs. 0.661 vs. 0.651) and female (0.702 vs. 0.671 vs. 0.674) subjects, indicating that the three values could be useful in detecting the occurrence of multiple metabolic risk factors. The appropriate cut-off values of BMI, waist circumference and WHtR to predict the presence of multiple metabolic risk factors were 22.85 and 23.30 kg/m² in males and females, respectively. Those of waist circumference and WHtR were 91.3 cm and 87.1 cm, 0.51 and 0.53 in males and females, respectively. CONCLUSION: The BMI, waist circumference and WHtR values can similarly predict the presence of multiple metabolic risk factors in Chinese subjects.

Zuogui Wan improves trabecular bone microarchitecture in ovariectomy-induced osteoporosis rats by regulating orexin-A and orexin receptor.

OBJECTIVE: To investigate the protective effects of Zuogui Wan (ZGW) on bone loss induced by ovariectomy (OVX) and its mechanism via orexin-A and orexin receptors in the osteoporosis rat model. METHODS: Fifty Sprague-Dawley female rats were randomly divided into sham-operated (sham) group and four OVX subgroups. Rats subjected to sham and OVX were treated with the vehicle (OVX, 1 mL/100 g weight, n = 10), 17ß-estradiol (E2, 50 µg*kg-1*d-1), and ZGW at the doses of 2.3 (ZGW-L) and 4.6 (ZGW-H) g/kg/day lyophilized powder daily for 3 months, respectively. The serum biochemical parameters of 17ß-estrogen (17ß-E2), tartrate-resistant acid phosphatase (TRACP-5b) and bone alkaline phosphatase (BALP) were measured by enzyme-linked immunosorbent assay. Hematoxylin-eosin staining was used to detect the changes in the morphological structure in bones. Microcomputed tomography was used to evaluate the bone mineral density and microarchitecture of the distal femur. The gene or protein expression of orexin-A, orexin receptor 1 (OX1R), orexin receptor 2 (OX2R), osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) were assayed by either quantitative polymerase chain reaction or Western blot analysis. RESULTS: Compared with the OVX group, ZGW could reduce the serum level of TRACP-5b and increased the serum levels of BALP and17ß-E2 (P < 0.01). Meanwhile, ZGW could prevent bone loss and improved bone trabecular microarchitecture by increasing the trabeculae structure thickness and trabecular number, and arranging the trabeculae structure properly. Compared with the OVX group, it was upregulated for the orexin-A and OX2R mRNA or protein expression from the hypothalamus and tibiae, and OPG in the tibiae of ZGW groups (P < 0.01, < 0.05), while downregulated for the OX1R mRNA and protein expression in the tibiae and hypothalamus and RANKL from the tibiae (P < 0.01). CONCLUSION: ZGW exhibited a protective effect for PMOP that may be mediated via orexin-A and orexin receptors regulation.

Feasibility of a 5G-Based Robot-Assisted Remote Ultrasound System for Cardiopulmonary Assessment of Patients With Coronavirus Disease 2019.

BACKGROUND: Traditional methods for cardiopulmonary assessment of patients with coronavirus disease 2019 (COVID-19) pose risks to both patients and examiners. This necessitates a remote examination of such patients without sacrificing information quality. RESEARCH QUESTION: The goal of this study was to assess the feasibility of a 5G-based robot-assisted remote ultrasound system in examining patients with COVID-19 and to establish an examination protocol for telerobotic ultrasound scanning. STUDY DESIGN AND METHODS: Twenty-three patients with COVID-19 were included and divided into two groups. Twelve were nonsevere cases, and 11 were severe cases. All patients underwent a 5G-based robot-assisted remote ultrasound system examination of the lungs and heart following an established protocol. Distribution characteristics and morphology of the lung and surrounding tissue lesions, left ventricular ejection fraction, ventricular area ratio, pericardial effusion, and examination-related complications were recorded. Bilateral lung lesions were evaluated by using a lung ultrasound score. RESULTS: The remote ultrasound system successfully and safely performed cardiopulmonary examinations of all patients. Peripheral lung lesions were clearly evaluated. Severe cases of COVID-19 had significantly more diseased regions (median [interquartile range], 6.0 [2.0-11.0] vs 1.0 [0.0-2.8]) and higher lung ultrasound scores (12.0 [4.0-24.0] vs 2.0 [0.0-4.0]) than nonsevere cases of COVID-19 (both, P < .05). One nonsevere case (8.3%; 95% CI, 1.5-35.4) and three severe cases (27.3%; 95% CI, 9.7-56.6) were complicated by pleural effusions. Four severe cases (36.4%; 95% CI, 15.2-64.6) were complicated by pericardial effusions (vs 0% of nonsevere cases, P < .05). No patients had significant examination-related complications. INTERPRETATION: Use of the 5G-based robot-assisted remote ultrasound system is feasible and effectively obtains ultrasound characteristics for cardiopulmonary assessment of patients with COVID-19. By following established protocols and considering medical history, clinical manifestations, and laboratory markers, this system might help to evaluate the severity of COVID-19 remotely.

Predicting Progression of COVID-19 Infection to Prioritize Medical Resource Allocation: A Novel Triage Model Based on Patient Characteristics and Symptoms at Presentation.

Background: The COVID-19 global pandemic has posed unprecedented challenges to health care systems all over the world. The speed of the viral spread results in a tsunami of patients, which begs for a reliable screening tool using readily available data to predict disease progression. Methods: Multicenter retrospective cohort study was performed to develop and validate a triage model. Patient demographic and non-laboratory clinical data were recorded. Using only the data from Zhongnan Hospital, step-wise multivariable logistic regression was performed, and a prognostic nomogram was constructed based on the independent variables identifies. The discrimination and calibration of the model were validated. External independent validation was performed to further address the utility of this model using data from Jinyintan Hospital. Results: A total of 716 confirmed COVID-19 cases from Zhongnan Hospital were included for model construction. Men, increased age, fever, hypertension, cardio-cerebrovascular disease, dyspnea, cough, and myalgia are independent risk factors for disease progression. External independent validation was carried out in a cohort with 201 cases from Jinyintan Hospital. The area under the curve (AUC) was 0.787 (95% confidence interval [CI]: 0.747-0.827) in the training group and 0.704 (95% CI: 0.632-0.777) in the validation group. Conclusions: We developed a novel triage model based on basic and clinical data. Our model could be used as a pragmatic screening aid to allow for cost efficient screening to be carried out such as over the phone, which may reduce disease propagation through limiting unnecessary contact. This may help allocation of limited medical resources.

Assessment of CPS + EG, Neo-Bioscore and Modified Neo-Bioscore in Breast Cancer Patients Treated With Preoperative Systemic Therapy: A Multicenter Cohort Study.

This study was to assess the prognosis stratification of the clinical-pathologic staging system incorporating estrogen receptor (ER)-negative disease, the nuclear grade 3 tumor pathology (CPS + EG), Neo-Bioscore, and a modified Neo-Bioscore system in breast cancer patients after preoperative systemic therapy (PST). A retrospective multicenter cohort study was conducted from 12 participating hospitals' databases from 2006 to 2015. Five-year disease free survival (DFS), disease specific survival (DSS), and overall survival (OS) were calculated using Kaplan-Meier Method. Area under the curve (AUC) of the three staging systems was compared. Wald test and maximum likelihood estimates in Cox proportional hazards model were used for multivariate analysis. A total of 1,077 patients were enrolled. The CPS + EG, Neo-Bioscore, and modified Neo-Bioscore could all stratify the DFS, DSS, and OS (all P < 0.001). While in the same stratum of Neo-Bioscore scores 2 and 3, the HER2-positive patients without trastuzumab therapy had much poorer DSS (P = 0.013 and P values < 0.01, respectively) as compared to HER2-positive patients with trastuzumab therapy and HER2-negative patients. Only the modified Neo-Bioscore had a significantly higher stratification of 5-year DSS than PS (AUC 0.79 vs. 0.65, P = 0.03). So, the modified Neo-Bioscore could circumvent the limitation of CPS + EG or Neo-Bioscore. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, identifier NCT03437837.

Gastric cancer in proximal site exerts poorer survival outcome with divergent genetic features than distal site.

BACKGROUND: Anatomical subsites always harbor specific biological features in carcinogenesis. The divergent prognosis of proximal gastric cancer (PGC) and distal gastric cancer (DGC) has been reported. The current study aimed to comprehensively interpret anatomic subsite-specific genomic profiles, which may improve the effectiveness of personalized management. METHODS: Survival and genomic data from the online Surveillance, Epidemiology, and End Results (SEER) and The Cancer Genome Atlas (TCGA) databases were queried for prognostic and genetic analysis, respectively. Propensity score matching (PSM) analysis was performed to balance patient epidemiological factors. Differentially expressed genes (DEGs) were analyzed using the DESeq algorithm. Functional enrichment was performed by the clusterProfiler package. The protein-protein interaction network of DEGs was predicted by the online STRING database. RESULTS: A total of 3,955 patient pairs were assembled by PSM in SEER data with even background characteristics. Prognostic analysis indicated worse overall survival of PGC than DGC (17 vs 20 months, p = 0.0002). Genetic analysis of TCGA database identified 280 DEGs, 90 of which were upregulated in the DGC group and the remaining 190 were upregulated in the PGC group. Functional enrichment analysis indicated that kallikrein serine protease activity, ion channel (Na+/Cl-) activity, and cytoskeleton constituent might be attributed to the poor prognosis observed in PGC. Furthermore, alcohol, retinol, and lipoprotein metabolism were the features for DGC malignancy. CONCLUSION: The current study first demonstrated that PGC exerts poorer survival outcome than DGC based on the SEER database. Further bioinformatic investigation depicts the specific genetic features for PGC and DGC, which may generate differences in tumor malignancy. Our findings provide promising genetic targets for future specific and individualized gastric cancer therapy.

Estimated prevalence and viral transmissibility in subjects with asymptomatic SARS-CoV-2 infections in Wuhan, China.

The role of subjects with asymptomatic SARS-CoV-2 infection in the current pandemic is not well-defined. Based on two different approaches to estimate the culminative attack rate (seroprevalence of antibodies against SARS-CoV-2, and a four compartment mathematical model) and the reported number of patients with COVID-19, the ratio of asymptomatic versus symptomatic SARS-CoV-2 infection was estimated to be 7 (95% CI: 2.8-12.4) in Wuhan, Hubei, China, the first epicenter of this pandemic, which has settled with no new cases. Together with detailed recording of the contact sources in a cohort of patients, and applying the estimations to an established mathematical model, the viral transmissibility of the subjects with asymptomatic SARS-CoV-2 infection is around 10% of that of the symptomatic patients (95% CI: 7.6%-12.3%). Public health measures/policies should address this important pool of infectious source in combat against this viral pandemic.

A four-compartment model for the COVID-19 infection-implications on infection kinetics, control measures, and lockdown exit strategies.

Objective: To analyse the impact and repercussions of the surge in healthcare demand in response to the COVID-19 pandemic, assess the potential effectiveness of various infection/disease control measures, and make projections on the best approach to exit from the current lockdown. Design: A four-compartment model was constructed for SARS-CoV-2 infection based on the Wuhan data and validated with data collected in Italy, the UK, and the US. The model captures the effectiveness of various disease suppression measures in three modifiable factors: (a) the per capita contact rate (ß) that can be lowered by means of social distancing, (b) infection probability upon contacting infectious individuals that can be lowered by wearing facemasks, personal hygiene, etc., and (c) the population of infectious individuals in contact with the susceptible population, which can be lowered by quarantine. The model was used to make projections on the best approach to exit from the current lockdown. Results: The model was applied to evaluate the epidemiological data and hospital burden in Italy, the UK, and the US. The control measures were identified as the key drivers for the observed epidemiological data through sensitivity analyses. Analysing the different lockdown exit strategies showed that a lockdown exit strategy with a combination of social separation/general facemask use may work, but this needs to be supported by intense monitoring which would allow re-introduction/tightening of the control measures if the number of new infected subjects increases again. Conclusions and relevance: Governments should act early in a swift and decisive manner for containment policies. Any lockdown exit will need to be monitored closely, with regards to the potential of lockdown reimplementation. This mathematical model provides a framework for major pandemics in the future.

Structure-based design of a T-cell receptor leads to nearly 100-fold improvement in binding affinity for pepMHC.

T-cell receptors (TCRs) are proteins that recognize peptides from foreign proteins bound to the major histocompatibility complex (MHC) on the surface of an antigen-presenting cell. This interaction enables the T cells to initiate a cell-mediated immune response to terminate cells displaying the foreign peptide on their MHC. Naturally occurring TCRs have high specificity but low affinity toward the peptide-MHC (pepMHC) complex. This prevents the usage of solubilized TCRs for diagnosis and treatment of viral infections or cancers. Efforts to enhance the binding affinity of several TCRs have been reported in recent years, through randomized libraries and in vitro selection. However, there have been no reported efforts to enhance the affinity via structure-based design, which allows more control and understanding of the mechanism of improvement. Here, we have applied structure-based design to a human TCR to improve its pepMHC binding. Our design method evolved based on iterative steps of prediction, testing, and generating more predictions based on the new data. The final design function, named ZAFFI, has a correlation of 0.77 and average error of 0.35 kcal/mol with the binding free energies of 26 point mutations for this system that we measured by surface plasmon resonance (SPR). Applying the filter that we developed to remove nonbinding predictions, this correlation increases to 0.85, and the average error decreases to 0.3 kcal/mol. Using this algorithm, we predicted and tested several point mutations that improved binding, with one giving over sixfold binding improvement. Four of the point mutations that improved binding were then combined to give a mutant TCR that binds the pepMHC 99 times more strongly than the wild-type TCR.

Direct Inhibition of MmpL3 by Novel Antitubercular Compounds.

MmpL3, an essential transporter involved in the export of mycolic acids, is the proposed target of a number of antimycobacterial inhibitors under development. Whether MmpL3 serves as the direct target of these compounds, however, has been called into question after the discovery that some of them dissipated the proton motive force from which MmpL transporters derive their energy. Using a combination of in vitro and whole-cell-based approaches, we here provide evidence that five structurally distinct MmpL3 inhibitor series, three of which impact proton motive force in Mycobacterium tuberculosis, directly interact with MmpL3. Medium- to high-throughput assays based on these approaches were developed to facilitate the future screening and optimization of MmpL3 inhibitors. The promiscuity of MmpL3 as a drug target and the mechanisms through which missense mutations located in a transmembrane region of this transporter may confer cross-resistance to a variety of chemical scaffolds are discussed in light of the exquisite vulnerability of MmpL3, its apparent mechanisms of interaction with inhibitors, and evidence of conformational changes induced both by the inhibitors and one of the most commonly identified resistance mutations in MmpL3.