Sulbactam-durlobactam: a ß-lactam/ß-lactamase inhibitor combination targeting Acinetobacter baumannii.

Sulbactam-durlobactam is a pathogen-targeted ß-lactam/ß-lactamase inhibitor combination that has been approved by the US FDA for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia caused by susceptible isolates of Acinetobacter baumannii-calcoaceticus complex (ABC) in patients 18 years of age and older. Sulbactam is a penicillin derivative with antibacterial activity against Acinetobacter but is prone to hydrolysis by ß-lactamases encoded by contemporary isolates. Durlobactam is a diazabicyclooctane ß-lactamase inhibitor with activity against Ambler classes A, C and D serine ß-lactamases that restores sulbactam activity both in vitro and in vivo against multidrug-resistant ABC. Sulbactam-durlobactam is a promising alternative therapy for the treatment of serious Acinetobacter infections, which can have high rates of mortality.

Sulbactam­durlobactam: a drug for treating lung infectionsAcinetobacter is a type of bacteria. One type, called CRAB, causes serious infections and can be fatal. CRAB is very hard to treat because most drugs no longer work. Sulbactam­durlobactam (SUL-DUR) is a drug that can kill CRAB. The US FDA approved SUL-DUR in May of 2023 for treating lung infections (pneumonia) caused by CRAB. This article explains how SUL-DUR works. Use of SUL-DUR and other drugs to treat these types of infections are discussed. In conclusion, SUL-DUR is a promising therapy for serious infections caused by CRAB.

The Pharmacokinetics/Pharmacodynamic Relationship of Durlobactam in Combination With Sulbactam in In Vitro and In Vivo Infection Model Systems Versus Acinetobacter baumannii-calcoaceticus Complex.

Sulbactam-durlobactam is a ß-lactam/ß-lactamase inhibitor combination currently in development for the treatment of infections caused by Acinetobacter, including multidrug-resistant (MDR) isolates. Although sulbactam is a ß-lactamase inhibitor of a subset of Ambler class A enzymes, it also demonstrates intrinsic antibacterial activity against a limited number of bacterial species, including Acinetobacter, and has been used effectively in the treatment of susceptible Acinetobacter-associated infections. Increasing prevalence of ß-lactamase-mediated resistance, however, has eroded the effectiveness of sulbactam in the treatment of this pathogen. Durlobactam is a rationally designed ß-lactamase inhibitor within the diazabicyclooctane (DBO) class. The compound demonstrates a broad spectrum of inhibition of serine ß-lactamase activity with particularly potent activity against class D enzymes, an attribute which differentiates it from other DBO inhibitors. When combined with sulbactam, durlobactam effectively restores the susceptibility of resistant isolates through ß-lactamase inhibition. The present review describes the pharmacokinetic/pharmacodynamic (PK/PD) relationship associated with the activity of sulbactam and durlobactam established in nonclinical infection models with MDR Acinetobacter baumannii isolates. This information aids in the determination of PK/PD targets for efficacy, which can be used to forecast efficacious dose regimens of the combination in humans.

Immediate Breast Cancer Reconstruction with or without Dermal Matrix or Synthetic Mesh Support: A Review and Network Meta-Analysis.

BACKGROUND: The use of acellular dermal matrices (ADMs) and synthetic mesh as part of implant-based breast reconstruction (IBBR) has been widely adopted. The authors investigated the clinical efficacy and safety of human ADM (HADM), xenograft ADM (XADM), and synthetic mesh as part of IBBR in postmastectomy patients as compared with previous standard implant reconstruction techniques using only a submuscular pocket for coverage. METHODS: A systematic search for randomized controlled trials and observational studies was performed. A frequentist network meta-analysis was conducted using the R packages netmeta and Shiny. RESULTS: Thirty-one of 2375 studies identified met the predefined inclusion criteria. Traditional submuscular placement (no ADM or mesh) had fewer overall complications compared with HADM [OR, 0.51; credible interval (CrI), 0.34 to 0.74], but there was no significant difference between no ADM or mesh and XADM (OR, 0.63; CrI, 0.29 to 1.32) or synthetic mesh (OR, 0.77; CrI, 0.44 to 1.30). No one treatment was superior with regards to implant loss. No ADM or mesh was associated with fewer infectious complications than HADM (OR, 0.6; CrI, 0.39 to 0.89). Both no ADM or mesh (OR, 0.45; CrI, 0.27 to 0.75) and XADM (OR, 0.46; CrI, 0.23 to 0.88) had reduced seroma compared with HADM. CONCLUSIONS: Selecting the appropriate IBBR should evaluate effectiveness, adverse events, and cost. Although it is difficult to select a universal ideal IBBR, evaluation using this network analysis may help guide both physicians and patients in their choice of procedure, especially in the case of HADM, which in this study was shown to be significantly predisposed to complications of infection and seroma. Randomized data are required comparing XADM versus synthetic meshes, given the similar risk profiles but significant cost discrepancy between the techniques.

Optimal Management of Asymptomatic Carotid Artery Stenosis: A Systematic Review and Network Meta-Analysis.

OBJECTIVE: Management of asymptomatic carotid artery stenosis (ACAS), including carotid endarterectomy (CEA), carotid artery stenting (CAS), and best medical treatment (BMT), remains inconsistent in current practice. Early studies reported a benefit of CEA vs. BMT; however, the current risk-benefit profile of invasive therapy lacks consensus. By evaluating the effects of modern BMT vs. invasive intervention on patient outcomes, this study aimed to influence the future management of ACAS. METHODS: A systematic review and series of network meta-analyses were performed assessing peri-operative (within 30 days) and long term (30 days - 5 years) stroke and mortality risk between ACAS interventions. Total stroke, major, minor, ipsilateral, and contralateral stroke subtypes were assessed independently. Traditional (pre-2000) and modern (post-2000) BMT were compared to assess clinical improvements in medical therapy over the previous two decades. Risks of myocardial infarction (MI) and cranial nerve injury (CNI) were also assessed. RESULTS: Seventeen reports of 14 310 patients with > 50% ACAS were included. CEA reduced the odds of a peri-operative stroke event occurring vs. CAS (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.1 - 2.2 [0 - 20 fewer/1 000]). CEA and CAS reduced the long term odds of minor strokes (OR 0.35, 95% CI 0.21 - 0.59 [20 fewer/1 000]) and ipsilateral strokes (OR 0.27, 95% CI 0.19 - 0.39 [30 fewer/1 000]) vs. all BMT. CEA reduced the odds of major strokes and combined stroke and mortality vs. traditional BMT; however, no difference was found between CEA and modern BMT. CAS reduced the odds of peri-operative MI (OR 0.49, 95% CI 0. 26 - 0.91) and CNI (OR 0.07, 95% CI 0.01 - 0.42) vs. CEA. CONCLUSION: Modern BMT demonstrates similar reductions in major stroke, combined stroke, and mortality to CEA. The overall risk reductions are low and data were unavailable to assess subgroups which may benefit from intervention. However, BMT carries the potential to reduce the requirement for surgical intervention in patients with ACAS.

Radiomic Detection of Malignancy within Thyroid Nodules Using Ultrasonography-A Systematic Review and Meta-Analysis.

Background: Despite investigation, 95% of thyroid nodules are ultimately benign. Radiomics is a field that uses radiological features to inform individualized patient care. We aimed to evaluate the diagnostic utility of radiomics in classifying undetermined thyroid nodules into benign and malignant using ultrasonography (US). Methods: A diagnostic test accuracy systematic review and meta-analysis was performed in accordance with PRISMA guidelines. Sensitivity, specificity, and area under curve (AUC) delineating benign and malignant lesions were recorded. Results: Seventy-five studies including 26,373 patients and 46,175 thyroid nodules met inclusion criteria. Males accounted for 24.6% of patients, while 75.4% of patients were female. Radiomics provided a pooled sensitivity of 0.87 (95% CI: 0.86−0.87) and a pooled specificity of 0.84 (95% CI: 0.84−0.85) for characterizing benign and malignant lesions. Using convolutional neural network (CNN) methods, pooled sensitivity was 0.85 (95% CI: 0.84−0.86) and pooled specificity was 0.82 (95% CI: 0.82−0.83); significantly lower than studies using non-CNN: sensitivity 0.90 (95% CI: 0.89−0.90) and specificity 0.88 (95% CI: 0.87−0.89) (p < 0.05). The diagnostic ability of radiologists and radiomics were comparable for both sensitivity (OR 0.98) and specificity (OR 0.95). Conclusions: Radiomic analysis using US provides a reproducible, reliable evaluation of undetermined thyroid nodules when compared to current best practice.

Value of the 21-gene expression assay in predicting locoregional recurrence rates in estrogen receptor-positive breast cancer: a systematic review and network meta-analysis.

PURPOSE: The Oncotype DX© 21-gene Recurrence Score (RS) estimates the risk of distant disease recurrence in early-stage estrogen receptor-positive, human epidermal growth factor receptor-2-negative (ER+/HER2- ) breast cancer. Using RS to estimate risk of locoregional recurrence (LRR) is less conclusive. We aimed to perform network meta-analysis (NMA) evaluating the RS in estimating LRR in ER+/HER2- breast cancer. METHODS: A NMA was performed according to PRISMA-NMA guidelines. Analysis was performed using R packages and Shiny. RESULTS: 16 studies with 21,037 patients were included (mean age: 55.1 years (range: 22-96)). The mean RS was 17.1 and mean follow-up was 66.4 months. Using traditional RS cut-offs, 49.7% of patients had RS < 18 (3944/7935), 33.8% had RS 18-30 (2680/7935), and 16.5% had RS > 30 (1311/7935). Patients with RS 18-30 (risk ratio (RR): 1.76, 95% confidence interval (CI): 1.32-2.37) and RS > 30 (RR: 3.45, 95% CI: 2.63-4.53) were significantly more likely to experience LRR than those with RS < 18. Using TAILORx cut-offs, 16.2% of patients had RS < 11 (1974/12,208), 65.8% had RS 11-25 (8036/12,208), and 18.0% with RS > 30 (2198/12,208). LRR rates were similar for patients with RS 11-25 (RR: 1.120, 95% CI: 0.520-2.410); however, those with RS > 25 had an increased risk of LRR (RR: 2.490, 95% CI: 0.680-9.390) compared to those with RS < 11. There was a stepwise increase in LRR rates when applying traditional and TAILORx cut-offs (both P < 0.050). CONCLUSION: RS testing accurately estimates LRR risk for patients being treated for early-stage ER+/HER2- breast cancer. Future prospective, randomized studies may validate the predictive value of RS in estimating LRR.

Optimal localization strategies for non-palpable breast cancers -A network meta-analysis of randomized controlled trials.

PURPOSE: Mammographic screening programmes have increased detection rates of non-palpable breast cancers. In these cases, wire-guided localization (WGL) is the most common approach used to guide breast conserving surgery (BCS). Several RCTs have compared WGL to a range of novel localization techniques. We aimed to perform a network meta-analysis (NMA) of randomized controlled trials (RCTs) comparing methods of non-palpable breast cancer localization. METHODS: A NMA was performed according to PRISMA-NMA guidelines. Analysis was performed using R packages and Shiny. RESULTS: 24 RCTs assessing 9 tumour localization methods in 4236 breasts were included. Margin positivity and reoperation rates were 16.9% (714/4236) and 14.3% (409/2870) respectively. Cryo-assisted localization had the highest margin positivity (28.2%, 58/206) and reoperation (18.9%, 39/206) rates. Compared to WGL (n = 2045 from 24 RCTs) only ultrasound guided localization (USGL) (n = 316 from 3 RCTs) significantly lowered margin positivity (odds ratio (OR): 0.192, 95% confidence interval (CI): 0.079-0.450) and reoperation rates (OR: 0.182, 95%CI: 0.069-0.434). Anchor-guided localization (n = 52, 1 RCT) significantly lowered margin positivity (OR: 0.229, 95%CI: 0.050-0.938) and magnetic-marker localization improved patient satisfaction (OR: 0.021, 95%CI: 0.001-0.548). There was no difference in operation duration, overall complications, haematoma, seroma, surgical site infection rates, or specimen size/vol/wt between methods. CONCLUSION: USGL and AGL are non-inferior to WGL for the localization of non-palpable breast cancers. The reported data suggests that these techniques confer reduced margin positivity rates and requirement for re-operation. However, caution when interpreting results relating to RCTs with small sample sizes and further validation is required in larger prospective, randomized studies.

Outcomes of Saphenous Vein Intervention in the Management of Superficial Venous Incompetence: A Systematic Review and Network Meta-analysis.

OBJECTIVE: To determine the most effective modality of intervention to treat saphenous vein insufficiency. SUMMARY OF BACKGROUND DATA: Endovenous therapies have instigated a paradigm shift in the management of superficial venous incompetence. When compared with open surgery, endovenous interventions (foam sclerotherapy, radiofrequency ablation, endovenous laser ablation (EVLA), mechanochemical ablation, and CAE closure) potentially offer reduced morbidity with similar procedural efficacy. METHODS: A systematic review and series of network meta-analyses of randomized controlled trials were performed assessing risks of procedural failure (within 6-weeks) and recurrence (6-weeks to 5-years), defined by ultrasound, between the different modalities of intervention for superficial venous incompetence. Treatment comparisons addressing risks of common adverse events, venous clinical severity score, and pain were also performed. RESULTS: A systematic search identified 51 articles, describing 36 randomized controlled trials, incorporating 7576 limbs. Outcome data on 10 modalities of intervention were analyzed up to 5-year follow-up. CAE resulted in the lowest risk of procedural failure within 6-weeks. Foam sclerotherapy had the highest risk of recurrence while high ligation with stripping (HLS) and Conservatrice Hemodynamique de l'Insuffisance Veineuse en Ambulatoire were ranked best to reduce long-term recurrence. No intervention increased risks of venous thromboembolism and there was minimal difference in morbidity between treatments. All interventions improved venous clinical severity score (range -1.02 to -4.95), however, radiofrequency ablation demonstrated the greatest improvement, followed by EVLA and HLS between 2 to 5-years. EVLA was associated with the highest risk of pain, while mechanochemical ablation offered the least. CONCLUSIONS: Although CAE offered the lowest risk of initial procedural failure, HLS resulted in lower rates of long-term recurrence without considerably increasing morbidity when compared with other endovenous options.

General data protection regulations (2018) and clinical research: perspectives of patients and doctors in an Irish university teaching hospital.

BACKGROUND: Europe's General Data Protection Regulation, or GDPR, is a set of data protection rules on the acquisition, storage, use, and access of personal data. GDPR came into effect in May 2018 when it was introduced across all 27 European Union (EU) member states and the European Economic Area (EEA). Maintaining compliance with this legislation has presented significant new challenges for ongoing clinical research. AIMS: To evaluate the knowledge and expectations of patients and doctors regarding GDPR and implications for future clinical research. METHODS: An anonymous 12-item questionnaire was circulated to patients and doctors at a University Teaching Hospital. Data analysis included descriptive statistics. RESULTS: Five hundred nine participants were included: 261 females (51.3%) and 248 males (48.7%). Three hundred fifty were patients (68.8%) and 159 were doctors (31.2%). Three hundred thirty-four participants were aware of GDPR (65.7%): 116 doctors (73.0%) and 218 patients (62.3%, P = 0.018). 71.1% of doctors were willing to allow their personal data to be processed anonymously as part of a clinical research project compared to 43.4% of patients (P < 0.001). 80.2% of patients believed explicit consent is needed before using personal data in clinical research in comparison to 60.4% of doctors (P < 0.001). Level of education impacted awareness of GDPR (P < 0.001); a higher level of education among patients increased GDPR familiarity (P < 0.001), however failed to impact doctor familiarity (P = 0.117). CONCLUSION: GDPR has introduced complexity to the processing and sharing of personal data among researchers. This study has identified differences in the perception of GDPR and willingness to consent to data being used in clinical research between doctors and patients. Measures to adequately inform prospective research participants on data processing and the evolving landscape of data protection regulation should be prioritised.

The hypervariable region of atlastin-1 is a site for intrinsic and extrinsic regulation.

Atlastin (ATL) GTPases catalyze homotypic membrane fusion of the peripheral endoplasmic reticulum (ER). GTP-hydrolysis-driven conformational changes and membrane tethering are prerequisites for proper membrane fusion. However, the molecular basis for regulation of these processes is poorly understood. Here we establish intrinsic and extrinsic modes of ATL1 regulation that involve the N-terminal hypervariable region (HVR) of ATLs. Crystal structures of ATL1 and ATL3 exhibit the HVR as a distinct, isoform-specific structural feature. Characterizing the functional role of ATL1's HVR uncovered its positive effect on membrane tethering and on ATL1's cellular function. The HVR is post-translationally regulated through phosphorylation-dependent modification. A kinase screen identified candidates that modify the HVR site specifically, corresponding to the modifications on ATL1 detected in cells. This work reveals how the HVR contributes to efficient and potentially regulated activity of ATLs, laying the foundation for the identification of cellular effectors of ATL-mediated membrane processes.

Rational design of a new antibiotic class for drug-resistant infections.

The development of new antibiotics to treat infections caused by drug-resistant Gram-negative pathogens is of paramount importance as antibiotic resistance continues to increase worldwide1. Here we describe a strategy for the rational design of diazabicyclooctane inhibitors of penicillin-binding proteins from Gram-negative bacteria to overcome multiple mechanisms of resistance, including ß-lactamase enzymes, stringent response and outer membrane permeation. Diazabicyclooctane inhibitors retain activity in the presence of ß-lactamases, the primary resistance mechanism associated with ß-lactam therapy in Gram-negative bacteria2,3. Although the target spectrum of an initial lead was successfully re-engineered to gain in vivo efficacy, its ability to permeate across bacterial outer membranes was insufficient for further development. Notably, the features that enhanced target potency were found to preclude compound uptake. An improved optimization strategy leveraged porin permeation properties concomitant with biochemical potency in the lead-optimization stage. This resulted in ETX0462, which has potent in vitro and in vivo activity against Pseudomonas aeruginosa plus all other Gram-negative ESKAPE pathogens, Stenotrophomonas maltophilia and biothreat pathogens. These attributes, along with a favourable preclinical safety profile, hold promise for the successful clinical development of the first novel Gram-negative chemotype to treat life-threatening antibiotic-resistant infections in more than 25 years.

In Vitro Antibacterial Activity and In Vivo Efficacy of Sulbactam-Durlobactam against Pathogenic Burkholderia Species.

The Gram-negative bacterial genus Burkholderia includes several hard-to-treat human pathogens: two biothreat species, Burkholderia mallei (causing glanders) and B. pseudomallei (causing melioidosis), and the B. cepacia complex (BCC) and B. gladioli, which cause chronic lung infections in persons with cystic fibrosis. All Burkholderia spp. possess an Ambler class A Pen ß-lactamase, which confers resistance to ß-lactams. The ß-lactam-ß-lactamase inhibitor combination sulbactam-durlobactam (SUL-DUR) is in clinical development for the treatment of Acinetobacter infections. In this study, we evaluated SUL-DUR for in vitro and in vivo activity against Burkholderia clinical isolates. We measured MICs of SUL-DUR against BCC and B. gladioli (n = 150), B. mallei (n = 30), and B. pseudomallei (n = 28), studied the kinetics of inhibition of the PenA1 ß-lactamase from B. multivorans and the PenI ß-lactamase from B. pseudomallei by durlobactam, tested for blaPenA1 induction by SUL-DUR, and evaluated in vivo efficacy in a mouse model of melioidosis. SUL-DUR inhibited growth of 87.3% of the BCC and B. gladioli strains and 100% of the B. mallei and B. pseudomallei strains at 4/4 µg/ml. Durlobactam potently inhibited PenA1 and PenI with second-order rate constant for inactivation (k2/K) values of 3.9 × 106 M-1 s-1 and 2.6 × 103 M-1 s-1 and apparent Ki (Kiapp) of 15 nM and 241 nM, respectively, by forming highly stable covalent complexes. Neither sulbactam, durlobactam, nor SUL-DUR increased production of PenA1. SUL-DUR demonstrated activity in vivo in a murine melioidosis model. Taken together, these data suggest that SUL-DUR may be useful as a treatment for Burkholderia infections.

N-Hydroxyformamide LpxC inhibitors, their in vivo efficacy in a mouse Escherichia coli infection model, and their safety in a rat hemodynamic assay.

UDP-3-O-(R-3-hydroxyacyl)-N-acetylglucosamine deacetylase (LpxC), the zinc metalloenzyme catalyzing the first committed step of lipid A biosynthesis in Gram-negative bacteria, has been a target for antibacterial drug discovery for many years. All inhibitor chemotypes reaching an advanced preclinical stage and clinical phase 1 have contained terminal hydroxamic acid, and none have been successfully advanced due, in part, to safety concerns, including hemodynamic effects. We hypothesized that the safety of LpxC inhibitors could be improved by replacing the terminal hydroxamic acid with a different zinc-binding group. After choosing an N-hydroxyformamide zinc-binding group, we investigated the structure-activity relationship of each part of the inhibitor scaffold with respect to Pseudomonas aeruginosa and Escherichia coli LpxC binding affinity, in vitro antibacterial potency and pharmacological properties. We identified a novel, potency-enhancing hydrophobic binding interaction for an LpxC inhibitor. We demonstrated in vivo efficacy of one compound in a neutropenic mouse E. coli infection model. Another compound was tested in a rat hemodynamic assay and was found to have a hypotensive effect. This result demonstrated that replacing the terminal hydroxamic acid with a different zinc-binding group was insufficient to avoid this previously recognized safety issue with LpxC inhibitors.

Discovery of an Orally Available Diazabicyclooctane Inhibitor (ETX0282) of Class A, C, and D Serine ß-Lactamases.

Multidrug resistant Gram-negative bacterial infections are an increasing public health threat due to rapidly rising resistance toward ß-lactam antibiotics. The hydrolytic enzymes called ß-lactamases are responsible for a large proportion of the resistance phenotype. ß-Lactamase inhibitors (BLIs) can be administered in combination with ß-lactam antibiotics to negate the action of the ß-lactamases, thereby restoring activity of the ß-lactam. Newly developed BLIs offer some advantage over older BLIs in terms of enzymatic spectrum but are limited to the intravenous route of administration. Reported here is a novel, orally bioavailable diazabicyclooctane (DBO) ß-lactamase inhibitor. This new DBO, ETX1317, contains an endocyclic carbon-carbon double bond and a fluoroacetate activating group and exhibits broad spectrum activity against class A, C, and D serine ß-lactamases. The ester prodrug of ETX1317, ETX0282, is orally bioavailable and, in combination with cefpodoxime proxetil, is currently in development as an oral therapy for multidrug resistant and carbapenem-resistant Enterobacterales infections.

Nucleotide-Dependent Dimerization and Conformational Switching of Atlastin.

A common feature of dynamin-related proteins (DRPs) is their use of guanosine triphosphate (GTP) to control protein dynamics. In the case of the endoplasmic- reticulum- (ER)-resident membrane protein atlastin (ATL), GTP binding and hydrolysis result in membrane fusion of ER tubules and the generation of a branched ER network. In this chapter, we describe two independent methods for dissecting the mechanism underlying nucleotide-dependent quaternary structure and conformational changes of ATL, focusing on size-exclusion chromatography coupled with multi-angle light scattering (SEC-MALS) and Förster resonance energy transfer (FRET), respectively. The high temporal resolution of the FRET-based assays enables the ordering of the molecular events identified in structural and equilibrium-based SEC-MALS studies. In combination, these complementary methods report on the oligomeric states of a system at equilibrium and timing of key steps along the enzyme's catalytic cycle. These methods are broadly applicable to proteins that undergo ligand-induced dimerization and/or conformational changes.

The architecture of EMC reveals a path for membrane protein insertion.

Approximately 25% of eukaryotic genes code for integral membrane proteins that are assembled at the endoplasmic reticulum. An abundant and widely conserved multi-protein complex termed EMC has been implicated in membrane protein biogenesis, but its mechanism of action is poorly understood. Here, we define the composition and architecture of human EMC using biochemical assays, crystallography of individual subunits, site-specific photocrosslinking, and cryo-EM reconstruction. Our results suggest that EMC's cytosolic domain contains a large, moderately hydrophobic vestibule that can bind a substrate's transmembrane domain (TMD). The cytosolic vestibule leads into a lumenally-sealed, lipid-exposed intramembrane groove large enough to accommodate a single substrate TMD. A gap between the cytosolic vestibule and intramembrane groove provides a potential path for substrate egress from EMC. These findings suggest how EMC facilitates energy-independent membrane insertion of TMDs, explain why only short lumenal domains are translocated by EMC, and constrain models of EMC's proposed chaperone function.

Physical Principles of Membrane Shape Regulation by the Glycocalyx.

Cells bend their plasma membranes into highly curved forms to interact with the local environment, but how shape generation is regulated is not fully resolved. Here, we report a synergy between shape-generating processes in the cell interior and the external organization and composition of the cell-surface glycocalyx. Mucin biopolymers and long-chain polysaccharides within the glycocalyx can generate entropic forces that favor or disfavor the projection of spherical and finger-like extensions from the cell surface. A polymer brush model of the glycocalyx successfully predicts the effects of polymer size and cell-surface density on membrane morphologies. Specific glycocalyx compositions can also induce plasma membrane instabilities to generate more exotic undulating and pearled membrane structures and drive secretion of extracellular vesicles. Together, our results suggest a fundamental role for the glycocalyx in regulating curved membrane features that serve in communication between cells and with the extracellular matrix.

Plasma and Intrapulmonary Concentrations of ETX2514 and Sulbactam following Intravenous Administration of ETX2514SUL to Healthy Adult Subjects.

ETX2514 is a novel ß-lactamase inhibitor that broadly inhibits Ambler class A, C, and D ß-lactamases. ETX2514 combined with sulbactam (SUL) in vitro restores sulbactam activity against Acinetobacter baumannii ETX2514-sulbactam (ETX2514SUL) is under development for the treatment of A. baumannii infections. The objective of this study was to determine and compare plasma, epithelial lining fluid (ELF), and alveolar macrophage (AM) concentrations following intravenous (i.v.) ETX2514 and sulbactam. Plasma, ELF, and AM concentrations of ETX2514 and sulbactam were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in 30 healthy adult subjects following repeated dosing (ETX2514 [1 g] and sulbactam [1 g] every 6 h [q6h], as a 3-h i.v. infusion, for a total of 3 doses). A bronchoalveolar lavage (BAL) was performed once in each subject at either 1, 2.5, 3.25, 4, or 6 h after the start of the last infusion. Penetration ratios were calculated from area under the concentration-time curve from 0 to 6 h (AUC0-6) values for total plasma and ELF using mean and median concentrations at the BAL fluid sampling times. Respective ELF AUC0-6 values, based on mean and median concentrations, were 40.1 and 39.4 mg · h/liter for ETX2514 and 34.7 and 34.5 mg · h/liter for sulbactam. Respective penetration ratios of ELF to total/unbound plasma concentrations, based on mean and median AUC0-6 values, of ETX2514 were 0.37/0.41 and 0.36/0.40, whereas these same ratio values were 0.50/0.81 and 0.50/0.80 for sulbactam. ETX2514 and sulbactam concentrations in AM were measurable and fairly constant throughout the dosing interval (median values of 1.31 and 1.01 mg/liter, respectively). These data support further study of ETX2514SUL for the treatment of pneumonia caused by multidrug-resistant A. baumannii (This study has been registered at ClinicalTrials.gov under identifier NCT03303924.).

Disrupted Hydrogen-Bond Network and Impaired ATPase Activity in an Hsc70 Cysteine Mutant.

The ATPase domain of members of the 70 kDa heat shock protein (Hsp70) family shows a high degree of sequence, structural, and functional homology across species. A broadly conserved residue within the Hsp70 ATPase domain that captured our attention is an unpaired cysteine, positioned proximal to the site of nucleotide binding. Prior studies of several Hsp70 family members show this cysteine is not required for Hsp70 ATPase activity, yet select amino acid replacements of the cysteine can dramatically alter ATP hydrolysis. Moreover, post-translational modification of the cysteine has been reported to limit ATP hydrolysis for several Hsp70s. To better understand the underlying mechanism for how perturbation of this noncatalytic residue modulates Hsp70 function, we determined the structure for a cysteine-to-tryptophan mutation in the constitutively expressed, mammalian Hsp70 family member Hsc70. Our work reveals that the steric hindrance produced by a cysteine-to-tryptophan mutation disrupts the hydrogen-bond network within the active site, resulting in a loss of proper catalytic magnesium coordination. We propose that a similarly altered active site is likely observed upon post-translational oxidation. We speculate that the subtle changes we detect in the hydrogen-bonding network may relate to the previously reported observation that cysteine oxidation can influence Hsp70 interdomain communication.