Disulfide stabilization reveals conserved dynamic features between SARS-CoV-1 and SARS-CoV-2 spikes.

SARS-CoV-2 spike protein (S) is structurally dynamic and has been observed by cryo-EM to adopt a variety of prefusion conformations that can be categorized as locked, closed and open. The locked conformations feature tightly packed trimers with structural elements incompatible with RBD in "up" position. For SARS-CoV-2 S, it has been shown that the locked conformations are transient under neutral pH. Probably due to their transience, locked conformations remain largely uncharacterized for SARS-CoV-1 S. Intriguingly, locked conformations were the only conformations captured for S proteins of bat and pangolin origin SARS-related coronaviruses. In this study, we introduced x1, x2, and x3 disulfides into SARS-CoV-1 S. Some of these disulfides have been shown to preserve rare locked conformations when introduced to SARS-CoV-2 S. Introduction of these disulfides allowed us to image a variety of locked and other rare conformations for SARS-CoV-1 S by cryo-EM. We identified bound cofactors and structural features that are associated with SARS-CoV-1 S locked conformations. We compare newly determined structures to other available spike structures of Sarbecoviruses to identify conserved features and discuss their possible functions.

Evidence-based practice of the puncture management in hemodialysis patients with difficult new arteriovenous fistula / 中国实用护理杂志

Objective:To explore the puncture management in hemodialysis patients with difficult new arteriovenous fistula based on the finest evidence-based best practice evidence and evaluate the clinical effects.Methods:A team was formed, according to theoretical framework basing on the evidence of continuous quality improvement model, the best evidence-based interventions were obtained by adopting evidence-based practice. Formulated review indicators, evaluated obstacles and promoting factors in the process of practice, and took corresponding action strategies. From February 2020 to June 2020, 30 patients admitted to the dialysis center of Sir Run Run Shaw Hospital of Zhejiang University were recruited in the baseline review group by convenience sampling method. From September 2020 to January 2021, 30 patients from September 2020 to January 2021 were recruited in the after-effect evaluation group. The baseline review group adopted the original difficult new arteriovenous fistula puncture management scheme, and the after-effect evaluation group adopted the difficult autologous new internal fistula puncture management scheme based on the best evidence. The success rate of one puncture of fistula, the incidence rate of hematoma during puncture and dialysis, the incidence rate of discontinuation of treatment and the compliance with examination indexes were compared in the patients before and after applying for the evidences.Results:Compared with the baseline review group, the success rate of one-time puncture of internal fistula in the aftereffect evaluation group increased from 36.7% (11/30) to 73.3% (22/30), the incidence rate of hematoma during puncture and dialysis were decreased from 33.3%(10/30) to 6.67%(2/30) and 40%(12/30) to 0, the incidence rate of discontinuation of treatment were decreased from 40%(12/30) to3.33% (1/30), the difference was statistically significant ( χ2 values were 6.67-11.88, P<0.05). The implementation rate of review indexes in the aftereffect evaluation group was higher than that in the baseline review group, and the difference was statistically significant ( P<0.05). Conclusions:Evidence-based practice can improve the success rate of difficult new arteriovenous fistula, and reduce the incidence of arteriovenous fistula hematoma, reduce treatment interruption, and better maintain the lifeline of patients.

Structures and function of locked conformations of SARS-CoV-2 spike

The spike (S) protein of SARS-CoV-2 has been observed in three distinct pre-fusion conformations: locked, closed and open. Of these, the function of the locked conformation remains poorly understood. Here we engineered a SARS-CoV-2 S protein construct "S-R/x3" to arrest SARS-CoV-2 spikes in the locked conformation by a disulfide bond. Using this construct we determined high-resolution structures confirming that the x3 disulfide bond has the ability to stabilize the otherwise transient locked conformations. Structural analyses reveal that wild-type SARS-CoV-2 spike can adopt two distinct locked-1 and locked-2 conformations. For the D614G spike, based on which all variants of concern were evolved, only the locked-2 conformation was observed. Analysis of the structures suggests that rigidified domain D in the locked conformations interacts with the hinge to domain C and thereby restrains RBD movement. Structural change in domain D correlates with spike conformational change. We propose that the locked-1 and locked-2 conformations of S are present in the acidic high-lipid cellular compartments during virus assembly and egress. In this model, release of the virion into the neutral pH extracellular space would favour transition to the closed or open conformations. The dynamics of this transition can be altered by mutations that modulate domain D structure, as is the case for the D614G mutation, leading to changes in viral fitness. The S-R/x3 construct provides a tool for the further structural and functional characterization of the locked conformations of S, as well as how sequence changes might alter S assembly and regulation of receptor binding domain dynamics.

Elastography for the diagnosis of high-suspicion thyroid nodules based on the 2015 American Thyroid Association guidelines: a multicenter study.

BACKGROUND: An accurate diagnosis for high-suspicion nodules based on the 2015 American Thyroid Association (ATA) guidelines would reduce unnecessary invasive examinations. Elastography is a useful tool for discriminating benign and malignant thyroid nodules. The aim of this study is to investigate the diagnostic efficiency of elastography for high-suspicion thyroid nodules based on the 2015 ATA guidelines in the Chinese population. METHODS: Thyroid nodules with high-suspicion characteristics based on the 2015 ATA guidelines were subjected to conventional ultrasound (US) and ultrasound strain elastography (USE) examinations at 12 hospitals from 4 geographic regions across China. Cytology/histology of thyroid nodules was used as a reference method. Receiver operating characteristic (ROC) curves were plotted to evaluate the diagnostic performance of the elasticity score (ES) and strain ratio (SR). Logistic regression analysis was used to determine the predictors of malignancy. RESULTS: Overall, a total of 1445 thyroid nodules (834 malignant, 611 benign) from 12 centers were included in the final analysis. The areas under the curve of the ES and SR were 0.828 and 0.732, respectively. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the ES were 92.4, 60.7, 79.0, 76.3 and 85.5%, respectively, and those of the SR were 81.1, 50.1, 68.9, 65.9 and 67.9%, respectively. The combination of the Thyroid Imaging Reporting and Data System (TI-RADS) and ES led to a significant increase in the sensitivity and NPV (97.1 and 91.9%, respectively) compared with the TI-RADS alone. Logistic regression analysis showed that microcalcifications (OR = 5.290), taller than wide (OR = 12.710), irregular margins (OR = 10.117), extrathyroidal extension (ETE; OR = 6.412), the ES (OR = 3.741) and the SR (OR = 1.083) were independent predictors of malignant thyroid nodules. The sensitivity, specificity, accuracy, PPV and NPV of the ES were all superior in nodules ≥1 cm than in those < 1 cm (95.0% vs 90.4, 68.8% vs 56.8, 85.9% vs 74.4, 85.2% vs 69.9, and 87.8% vs 84.2%, respectively). CONCLUSIONS: Elastography combined with the ES is a valuable tool for the assessment of high-suspicion thyroid nodules based on the 2015 ATA guidelines, especially in nodules ≥1 cm.

Correlation between treatment-related lymphopenia and pathologic response in esophageal squamous cell carcinoma patients undergoing neoadjuvant chemoradiotherapy / 中华放射肿瘤学杂志

Objective To investigate the relationship between treatment-related lymphopenia and pathologic complete response (pCR) to neoadjuvant chemoradiotherapy (CRT) in patients with esophageal squamous cell carcinoma (ESCC).Methods Clinical data of 220 ESCC patients treated with neoadjuvant CRT followed by surgery between 2002 and 2016 were retrospectively analyzed.Absolute lymphocyte count was determined before and at 1 month after neoadjuvant CRT.Treatment-related lymphopenia was graded using Common Terminology Criteria for Adverse Events (CTCAE,4.0 version).The relationship between lymphopenia,pCR and recurrence was evaluated by chi-square test and Cox's regression model.Results Ninety-five patients (43.2％) achieved a pCR after neoadjuvant CRT and 71 cases (32.3％) recurred postoperatively.During neoadjuvant CRT,the incidence rates of grade 0,1,2,3,and 4 lymphopenia were 1.8％,6.8％,31.4％,38.2％,and 21.8％,respectively.Patients with grade 4 lymphopenia had a significantly lower pCR rate than those with grade 0-3 lymphopenia (22.9％ vs.48.8％,P=0.001).Moreover,grade 4 lymphopenia was significantly associated with a higher risk of recurrence (45.8％ vs.28.5％,P=0.023).Multivariate analysis identified that primary tumor length,tumor location and radiation dose were the independent predictors for grade 4 lymphopenia during neoadjuvant CRT (P=0.013,0.001,0.002).Conclusions The incidence of grade 4 lymphopenia in ESCC patients undergoing neoadjuvant CRT is correlated with a low pCR rate and a high risk of recurrence.Lymphopenia can be used as an economic and effective predictor for pCR.

Preliminary research of sound velocity tissue quantification on liver fibrosis stage / 中华超声影像学杂志

Objective To evaluate sound velocity tissue quantification ( SVQ ) for the quantitative assessment of liver fibrosis stage in chronic hepatitis B ,and to evaluate the correlation between diagnostic performance of sound velocity tissue quantification and blood parameters . Methods From the May of 2013 to May of 2014 ,collect ninety‐nine patients with chronic hepatitis B who was diagnosed by clinic and / or liver biopsy as experiment group ,and thirty healthy volunteers as control group at the same time . The experiment group and control group were evaluated with to measurement the zone speed index ( ZSI) ,and blood cell count . The AST/PLT ratio index ( APRI) was calculated according the following formula , APRI=AST(ULN)/PLT(109/L) . The liver biopsy was performed in the same day with SVQ and all blood parameters .ZSI and APRI were compared by correlation with liver fibrosis stage in chronic hepatitis B . Referring to the histologic fibrosis stage on liver biopsy ,all the ZSI and the APRI value were assessed by using ROC curve analysis . The corresponding cut‐off value ,sensitivity and specificity were also calculated andcompared.Results 1)ThemeanvaluesofAPRIwere(15.9±5.7)m/sforpatientswithS0,(28.1± 2 .8)m/s for patients with S1 ,(35 .8 ± 1 .2)m/s for patients with S2 ,(42 .6 ± 0 .8)m/s for patients with S3 , and (46 .3 ± 1 .3)m/s for patients with S4 .2)Accordingly ,the areas under the ROC curve for ZSI and APRI were 0 .875 and 0 .762 for S≥S1 ,0 .832 and 0 .597 for S≥S2 ,0 .913 and 0 .675 for S≥S3 ,0 .891 and 0 .709 for S≥S4 ,respectively . Conclusions The ZSI and APRI all could be used to evaluate the stage of liver fibrosis ,but the ZSI index is superior to APRI in assessing the stage of liver fibrosis . SVQ could provide object and accurate image ,the quantitative analysis of tissue could timely and accurately evaluate the severity of liver fibrosis .

Stability of phonetics to determine the horizontal jaw relation in healthy adults / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The aim of this study was to compare the mandibular position when speaking with the intercuspal position and to check the stability of phonetics when determining the horizontal jaw relation in healthy adults.</p><p><b>METHODS</b>A total of 19 healthy volunteers were recruited. Seven Chinese letters, namely, /xi/, /er/, /yi/, /ci/, /mi/, /ni/, and /ri/, were chosen in the test. O-bite was used to record the mandibular position when speaking these letters. A full-adjusted articulator was used to find the mandibular position during speech, and the mandibular position was measured using a vernier caliper. The mandibular position during speech with intercuspal position was compared in both anterior-posterior and left-right directions of the horizontal plane. Multi-factor analysis of variance was conducted for the statistical analysis of the effect of objects and letters on the mandibular position.</p><p><b>RESULTS</b>1) The mandibular position was in front of the intercuspal occlusion position when speaking all seven letters, and almost no deviation was observed in the left and right directions (the mandibular position value of 82% was in the range of 0.5 mm). 2) Different objects had different mandibular positions during speech, whereas different letters did not. The distance between the centric relation position and the intercuspal position had a positive correlation with the range of the mandibular position during speech.</p><p><b>CONCLUSION</b>The mandibular position was in front of the intercuspal position when speaking all seven words in the test. In the same object, the mandibular position was stable during speech.</p>

Quantitative evaluation in the stage of chronic nephrosis by shear-wave elasticity technology / 中华超声影像学杂志

Objective To investigate the diagnostic value of the shear-wave elasticity (SWE) imaging technology on the quantitative diagnosis of chronic nephrosis stage.Methods Sixty patients with nephrosis (nephrosis group) were evaluated with SWE and the renal function test.The Young's modulus value and the renal function were measured,and the results were compared with those of twenty healthy subjects (control group).Results Twenty cases of healthy control group were definited as R0.Sixty patients of nephrosis group were divided into four groups according to renal function:R1-R4.The Young's modulus of the nephrosis group was significantly higher than the control group (P ＜0.01).There were also statistically significant differences among each stage of the nephrosis group (except R1 and R2 of nephrosis group)(P ＜ 0.01).According the ROC curve,the cut-off value of the Young's modulus was 5.53 kPa when maximum area under the curve equal to 0.886,the sensitivity and specificity were 81.70％ and 80.40％.The Young's modulus value and renal function were positively correlated with the stage of nephrosis.The areas under the ROC curves for the Young's modulus,urea nitrogen and csytatin C were 0.965,0.950,0.965 for ≥R3,0.978,0.912,0.961 for =R4,respectively.Conclusions SWE imaging technology provided a new quantitative index for the stage of nephrosis through quantizing the elasticity of the tissue.

Evaluation of shear wave elastography in diffuse thyroid disease / 中华超声影像学杂志

Objective To explore the value of shear wave elastography (SWE) in diffuse thyroid disease.Methods The elastic modulus were detected by SWE in 41cases of diffuse thyroid disease [including 16 cases of Graves' disease (GD),16 cases of Hashimoto' s thyroiditis (HT) and 9 cases of subacute thyroiditis(SAT)] and 30 cases of healthy volunteers.The elastic modulus,including Emean,Emin and Emax,were measured and compared.Results Compared with the normal group[Emean(15.7-± 2.5)kPa,Emin(11.6 ± 2.4)kPa and Emax (20.2 ± 3.0)kPa],the Emean[(20.4 ± 4.7)kPa],Emin[(14.4-± 3.8)kPa] and Emax [(27.8 ± 7.3)kPa] of GD,the Emean [(18.4-± 5.0)kPa] and Emax [(25.2 ± 5.8)kPa] of HT,and the Emean[(11.0 ± 2.9)kPa] and Emin [(6.0 ± 2.7)kPa] of the SAT were different significantly(P =0.001,0.007,0.001 ; P =0.045,0.001 ; P =0.000,0.000).There were significant differences between the SAT and the other two groups,namely GD and HT (P ＜0.05).Such differences,however,were not found between GD and HT (P ＞0.05).Conclusions SWE can be used to measure the elastic modulus of the thyroid tissue quantitatively and objectively,serving as a useful technique to predict the diffuse thyroid disease.