Investigation into the role of an extracellular loop in mediating proton-evoked inhibition of voltage-gated sodium channels

Proton-evoked activation of sensory neurons is counteracted by inhibition of voltage-gated Na+ channels, and the low acid-sensitivity of sensory neuron of the African naked mole-rat (ANMr) was reported to be due to a strong proton-evoked block of ANMrNav1.7. Here we aimed to reevaluate the role of the suggested negatively-charged motif in the ANMrNav1.7 domain IV P-loop for inhibition by protons. Patch clamp recordings were performed on the recombinant α-subunits Nav1.2–1.8. The insertion of the negatively charged motif (EKE) of ANMrNav1.7 into human Nav1.7 results in an increased proton-evoked tonic inhibition, but also in a reduced channel function. While the voltage-dependency of fast inactivation is changed in hNav1.7-EKE, pH 6.4 fails to induce a significant shift in both constructs. Proton-evoked inhibition of other channel α-subunits reveals a discrete differential inhibition among α-subunits with hNav1.7 displaying the lowest proton-sensitivity. The mutant hNav1.7-EKE displays a similar proton-sensitivity as Nav1.2, Nav1.3, Nav1.6 and Nav1.8. Overall, a correlation between proton-evoked inhibition and motif charge was not evident. Accordingly, a homology model of hNav1.7 shows that the EKE motif residues do not contribute to the pore lumen. Our data confirms that a negative charge of a postulated proton-motif encodes for a high proton-sensitivity when inserted into hNav1.7. However, a negatively charged motif is not a reliable predictor for a high proton-sensitivity in other α-subunits. Given the distance of the proton-motif from the pore mouth it seems unlikely that a blocking mechanism involving direct obstruction of the pore underlies the observed proton-evoked channel inhibition

A systematic examination of the bone destruction pattern of the two-shot technique

Introduction: The two-shot technique is an effective stopping power method. The precise mechanisms of action on the bone and soft-tissue structures of the skull; however, remain largely unclear. The aim of this study is to compare the terminal ballistics of the two-shot and single-shot techniques. Materials and Methods: 40 fresh pigs′ heads were randomly divided into 4 groups (n = 10). Either a single shot or two shots were fired at each head with a full metal jacket or a semi-jacketed bullet. Using thin-layer computed tomography and photography, the diameter of the destruction pattern and the fractures along the bullet path were then imaged and assessed. Results: A single shot fired with a full metal jacket bullet causes minor lateral destruction along the bullet path. With two shots fired with a full metal jacket bullet, however, the maximum diameter of the bullet path is significantly greater (P < 0.05) than it is with a single shot fired with a full metal jacket bullet. In contrast, the maximum diameter with a semi-jacketed bullet is similar with the single-shot and two-shot techniques. Conclusion: With the two-shot technique, a full metal jacket bullet causes a destruction pattern that is comparable to that of a single shot fired with a semi-jacketed bullet

Clinical and molecular characteristics of HER2-low-positive breast cancer: pooled analysis of individual patient data from four prospective, neoadjuvant clinical trials

Background The development of anti-HER2 antibody-drug conjugates opens new therapeutic options for patients with breast cancer, including patients with low expression of HER2. To characterise this new breast cancer subtype, we have compared the clinical and molecular characteristics of HER2-low-positive and HER2-zero breast cancer, including response to neoadjuvant chemotherapy and prognosis. Methods In this pooled analysis of individual patient data, we evaluated a cohort of 2310 patients with HER2non-amplified primary breast cancer that were treated with neoadjuvant combination chemotherapy in four prospective neoadjuvant clinical trials (GeparSepto, NCT01583426; GeparOcto, NCT02125344; GeparX, NCT02682693; Gain-2 neoadjuvant, NCT01690702) between July 30, 2012, and March 20, 2019. Central HER2 testing was done prospectively before random assignment of participants in all trials. HER2-low-positive status was defined as immunohistochemistry (IHC) 1+ or IHC2+/in-situ hybridisation negative and HER2-zero was defined as IHC0, based on the American Society of Clinical Oncology/College of American Pathologists guidelines. Disease-free survival and overall survival data were available for 1694 patients (from all trials except GeparX) with a median followup of 46.6 months (IQR 35.0-52.3). Bivariable and multivariable logistic regression models and Cox-proportional hazards models were performed based on a predefined statistical analysis plan for analysis of the endpoints pathological complete response, disease-free survival, and overall survival. Findings A total of 1098 (47.5%) of 2310 tumours were HER2-low-positive and 1212 (52.5%) were HER2-zero. 703 (64.0%) of 1098 patients with HER2-low-positive tumours were hormone receptor positive, compared with 445 (36.7%) of 1212 patients with HER2-zero tumours (p<0.0001). HER2-low-positive tumours had a significantly lower pathological complete response rate than HER2-zero tumours (321 [29.2%] of 1098 vs 473 [39.0%] of 1212, p=0.0002). Pathological complete response was also significantly lower in HER2-low-positive tumours versus HER2-zero tumours in the hormone receptor-positive subgroup (123 [17.5%] of 703 vs 105 [23.6%] of 445, p=0.024), but not in the hormone receptor-negative subgroup (198 [50.1%] of 395 vs 368 [48.0%] of 767, p=0.21). Patients with HER2-low-positive tumours had significantly longer survival than did patients with HER2-zero tumours (3-year disease-free survival: 83.4% [95% CI 80.5-85.9] vs 76.1% [72.9-79.0]; stratified log-rank test p=0.0084; 3-year overall survival: 91.6% [84.9-93.4] vs 85.8% [83.0-88.1]; stratified log-rank test p=0.0016). Survival differences were also seen in patients with hormone receptor-negative tumours (3-year disease free survival: 84.5% [95% CI 79.5-88.3] vs 74.4% [70.2-78.0]; stratified log-rank test p=0.0076; 3-year overall survival: 90.2% [86.0-93.2] vs 84.3% [80.7-87.3], stratified log-rank test p=0.016), but not in patients with hormone receptor-positive tumours (3-year disease-free survival 82.8% [79.1-85.9] vs 79.3% [73.9-83.7]; stratified log-rank test p=0.39; 3-year overall survival 92.3% [89.6-94.4] vs 88.4% [83.8-91.8]; stratified log-rank test p=0.13). Interpretation Our results show that HER2-low-positive tumours can be identified as new subgroup of breast cancer by standardised IHC, distinct from HER2-zero tumours. HER2-low-positive tumours have a specific biology and show differences in response to therapy and prognosis, which is particularly relevant in therapy-resistant, hormone receptor-negative tumours. Our results provide a basis for a better understanding of the biology of breast cancer subtypes and the refinement of future diagnostic and therapeutic strategies. Funding German Cancer Aid (Deutsche Krebshilfe). Copyright (c) 2021 Elsevier Ltd. All rights reserved