Recurrence of Non-Small Cell Lung Cancer With Visceral Pleural Invasion: A Secondary Analysis of a Randomized Clinical Trial.

Importance: The randomized clinical trial Cancer and Leukemia Group B (CALGB) 140503 showed that for patients with clinically staged T1N0 non-small cell lung cancer (NSCLC; ≤2 cm), sublobar resections were associated with similar oncological outcomes to those after lobar resection. The association of the extent of parenchymal resection with recurrence and survival in patients with tumors pathologically upstaged to T2 based on visceral pleural invasion (VPI) is controversial. Objective: To determine survival and recurrence rates in patients with small peripheral pT2 NSCLC (≤2 cm) that was treated by either lobar or sublobar resection in CALGB 140503. Design, Participants, and Setting: CALGB 140503, a randomized multicenter noninferiority trial, included 697 patients with small peripheral NSCLC that was clinically staged as T1N0. Enrollment was from June 2007 through March 2017 at 83 participating institutions, and after a median follow-up of 7 years, the primary outcome of disease-free survival after sublobar resection was noninferior to that after lobar resection. Intervention: Lobar or sublobar resection. Main Outcomes and Measures: Survival end points were estimated by the Kaplan-Meier estimator. Hazard ratios and 95% CIs were estimated using stratified Cox proportional hazard models. Results: Of 679 participants, 390 (57.4%) were female, and the median (range) age was 67.8 (37.8-89.7) years. Among 697 patients randomized, 566 (81.2%) had pT1 tumors (no VPI) and 113 (16.2%) had pT2 tumors (VPI). Five-year disease-free survival was 65.9% (95% CI, 61.9%-70.2%) in patients with pT1 compared with 53.3% (95% CI, 44.3%-64.1%) in patients with pT2 tumors (stratified log-rank: P = .02). Disease recurrence developed in 27.6% of patients with pT1 (locoregional only: 60 [10.8%]; distant only: 81 [14.6%]) and 41.6% of those with pT2 (locoregional only: 17 [15.0%]; distant only: 27 [23.9%]). Five-year recurrence-free survival was 73.1% (95% CI, 69.2%-77.1%) for pT1 tumors and 58.2% (95% CI, 49.2%-68.8%) for pT2 tumors (stratified log-rank: P = .01). There were no intergroup differences in disease-free or recurrence-free survival based on the extent of parenchymal resection. Conclusions and Relevance: The results of this secondary analysis suggest that compared with patients with tumors without VPI, patients who had tumors with VPI had worse disease-free and recurrence-free survival and a higher rate of local and distant disease recurrence. These high rates of recurrence were independent of the extent of parenchymal resection, and these data support the inclusion of these patients in adjuvant therapy trials. Trial Registration: ClinicalTrials.gov Identifier: NCT0049933.

Family-centred care interventions for children with chronic conditions: A scoping review.

INTRODUCTION: Children with chronic conditions have greater health care needs than the general paediatric population but may not receive care that centres their needs and preferences as identified by their families. Clinicians and researchers are interested in developing interventions to improve family-centred care need information about the characteristics of existing interventions, their development and the domains of family-centred care that they address. We conducted a scoping review that aimed to identify and characterize recent family-centred interventions designed to improve experiences with care for children with chronic conditions. METHODS: We searched Medline, Embase, PsycInfo and Cochrane databases, and grey literature sources for relevant articles or documents published between 1 January 2019 and 11 August 2020 (databases) or 7-20 October 2020 (grey literature). Primary studies with ≥10 participants, clinical practice guidelines and theoretical articles describing family-centred interventions that aimed to improve experiences with care for children with chronic conditions were eligible. Following citation and full-text screening by two reviewers working independently, we charted data covering study characteristics and interventions from eligible reports and synthesized interventions by domains of family-centred care. RESULTS: Our search identified 2882 citations, from which 63 articles describing 61 unique interventions met the eligibility criteria and were included in this review. The most common study designs were quasiexperimental studies (n = 18), randomized controlled trials (n = 11) and qualitative and mixed-methods studies (n = 9 each). The most frequently addressed domains of family-centred care were communication and information provision (n = 45), family involvement in care (n = 37) and access to care (n = 30). CONCLUSION: This review, which identified 61 unique interventions aimed at improving family-centred care for children with chronic conditions across a range of settings, is a concrete resource for researchers, health care providers and administrators interested in improving care for this high-needs population. PATIENT OR PUBLIC CONTRIBUTION: This study was co-developed with three patient partner co-investigators, all of whom are individuals with lived experiences of rare chronic diseases as parents and/or patients and have prior experience in patient engagement in research (I. J., N. P., M. S.). These patient partner co-investigators contributed to this study at all stages, from conceptualization to dissemination.

Risk-adjusted discrete increases in length of stay by complication following anatomic lung resection: an analysis of 32 133 cases across the USA.

OBJECTIVES: Prior studies have associated morbidity following anatomic lung resection with prolonged postoperative length of stay; however, each complication's individual impact on length of stay as a continuous variable has not been studied. The purpose of this study was to determine the risk-adjusted increase in length of stay associated with each individual postoperative complications following anatomic lung resection. METHODS: Patients who underwent anatomic lung resection cataloged in the prospectively collected American College of Surgeons National Surgical Quality Improvement Program participant use file, 2005-2018, were targeted. The association between preoperative characteristics, postoperative complications and length of stay in days was tested. A negative binomial model adjusting for the effect of preoperative characteristics and 18 concurrent postoperative complications was used to generate incidence rate ratios. This model was fit to generate risk-adjusted increases in length of stay by complication. RESULTS: Of 32 133 patients, 5065 patients (15.8%) experienced at least one post-operative complication. The most frequent complications were pneumonia (n = 1829, 5.7%), the need for transfusion (n = 1794, 5.6%) and unplanned reintubation (n = 1064, 3.3%). The occurrence of each of the 18 individual complications was associated with significantly increased length of stay. This finding persisted after risk-adjustment, with the greatest risk-adjusted increases being associated with prolonged ventilation (+17.4 days), followed by septic shock (+17.2 days), acute renal failure (+16.5 days) and deep surgical site infection (+13.2 days). CONCLUSIONS: All 18 postoperative complications studied following anatomic lung resection were associated with significant risk-adjusted increases in length of stay, ranging from an increase of 17.4 days with prolonged ventilation to 2.6 days following the need for transfusion.

ECG and Atrial Appendage Doppler Discordance Is Common in Patients Undergoing Cardiac Surgery: Prospective Study.

Background: Patients with atrial fibrillation (AF) remain at increased risk of thromboembolism despite apparent maintenance of sinus rhythm with the cause often attributed to periods of asymptomatic AF. Atrial mechanical discordance, with the body of the left atrium (LA) in sinus rhythm and the left atrial appendage (LAA) in AF may also be a contributor. Objectives: The purpose of this study was to assess the frequency of electrocardiogram (ECG) rhythm and LAA and/right atrial appendage (RAA) Doppler ejection phenotype (transesophageal echocardiography [TEE]) discordance in patients undergoing cardiac surgery. Methods: A total of 124 patients undergoing coronary artery bypass graft (CABG), CABG and valve surgery, or isolated valve repair or replacement (valve ± CABG) were prospectively studied. Intraoperative surface ECG rhythm strip and TEE were performed before cardiopulmonary bypass. The ECG and TEE LAA/RAA Doppler spectrum were independently classified as sinus or AF. Results: Of 107 patients (age 65 ± 12 years; 31% female; 65% CABG, 31% valve ± CABG) without a history of AF, 39 (36%) had ECG and LAA and/or RAA discordance (ECG/LAA Doppler discordance, n = 12 [11%]; ECG/RAA Doppler discordance, n = 35 [33%]). There was no significant difference between concordant and discordant groups with regard to age, gender, history of hypertension, diabetes, heart failure, or stroke (all P > 0.05). Conclusions: A large minority of patients without a history of AF undergoing cardiac surgery have ECG/atrial appendage Doppler discordance, a setting that may promote thromboembolism in non-anticoagulated patients. Clinical parameters do not identify patients at increased risk for discordance.

Revisiting the Application of Machine Learning Approaches in Predicting Aqueous Solubility.

The solubility of chemical substances in water is a critical parameter in pharmaceutical development, environmental chemistry, agrochemistry, and other fields; however, accurately predicting it remains a challenge. This study aims to evaluate and compare the effectiveness of some of the most popular machine learning modeling methods and molecular featurization techniques in predicting aqueous solubility. Although these methods were not implemented in a competitive environment, some of their performance surpassed previous benchmarks, offering gradual but significant improvements. Our results show that methods based on graph convolution and graph attention mechanisms demonstrated exceptional predictive abilities with high-quality data sets, albeit with a sensitivity to data noise and errors. In contrast, models leveraging molecular descriptors not only provided better interpretability but also showed more resilience when dealing with inherent noise and errors in data. Our analysis of over 4000 molecular descriptors used in various models identified that approximately 800 of these descriptors make a significant contribution to solubility prediction. These insights offer guidance and direction for future developments in solubility prediction.

Robotic-assisted ectopic mediastinal parathyroidectomy: a single institution experience and operative review for the thoracic surgeon.

Background: Parathyroidectomy remains the only definitive cure for primary hyperparathyroidism (PHPT). In rare cases, ectopic hyperfunctioning glands are located in the mediastinum, necessitating a thoracic surgical approach. The objective of this project was to review a single high-volume institutional experience of this presentation, with specific attention to the use of a robotic-assisted thoracic surgery (RATS) approach. Methods: This was a single-center, 5-year retrospective cohort study. All patients who underwent RATS mediastinal mass resection (MMR) for PHPT at the University of Colorado Anschutz Medical Campus were targeted for inclusion. Patient cases were reviewed for demographics, history, operative data, laboratory values, and postoperative course. Results: Eight patients underwent RATS-MMR for PHPT between 2018-2023. Median [interquartile range] operative time was 178 [138-213] minutes, and length of stay was 2.0 [1.5-2.0] days. One patient experienced post-operative chylothorax requiring dietary modification. There were no other 30-day complications or readmissions. Final pathology confirmed intrathymic parathyroid tissue in all patients. All patients achieved cure of PHPT. Conclusions: The robotic-assisted approach has low morbidity and associated hospital length of stay and can be safely used to cure PHPT. As this is a rare pathology with an infrequently utilized surgical approach, it is important to critically discuss the diagnostic evaluation and operative course, aimed at educating the thoracic surgeon who may encounter and assist in the management of these patients.

Syncope in the Emergency Department: A Case Report of a Rare Presentation of Favism.

Consumption of fava beans in a patient with glucose-6-phosphate dehydrogenase (G6PD) deficiency, also called favism, can lead to a haemolytic crisis. We report the case of a 69-year-old patient of Iranian origin admitted to the emergency department following syncope. The patient's comprehensive interview and blood analysis revealed that the patient presented a haemolytic crisis triggered by fava beans consumption, due to previously undiagnosed G6PD deficiency. The pathophysiology of favism is complex and clinical presentations of G6PD deficiency are numerous due to multiple genetic variants. Indirect signs, such as the presence of methemoglobinaemia and hemighosts on the blood smear, can aid in the diagnosis. This case highlights the importance of considering G6PD deficiency as a potential diagnosis in case of haemolytic crisis, even in elderly patients.

Corrigendum: Do we need to reframe risk once again?

[This corrects the article DOI: 10.4102/jamba.v15i1.1587.].

Virtual Reality Training for Central Venous Catheter Placement: An Interventional Feasibility Study Incorporating Virtual Reality Into a Standard Training Curriculum of Novice Trainees.

OBJECTIVES: This study assess the feasibility of integrating virtual reality (VR) simulation into the central venous catheter (CVC) placement training curriculum. DESIGN: The study consists of 3 parts: (1) Evaluating current manikin-based training for CVC placement through surveys for senior first-year anesthesia residents and cardiac anesthesia faculty who supervise resident performing the procedure; (2) Interventional study training novice trainees with VR simulator and assessing their reaction satisfaction; and (3) pilot study integrating VR training sessions into CVC training curriculum for first-year anesthesia residents. SETTING: Conducted at a single academic-affiliated medical center from December 2022 to August 2023. PARTICIPANTS: Junior first-year anesthesia residents. INTERVENTIONS: VR training sessions for CVC placements using the Vantari VR system. MEASUREMENTS AND MAIN RESULTS: Primary outcome: novice trainees' satisfaction with VR training for CVC procedure. Satisfaction of resident and faculty with standard manikin-based training was also collected. Faculty expressed concerns about residents' confidence and perceived knowledge in performing CVC placement independently. Novice trainees showed high satisfaction and perceived usefulness with VR training, particularly in understanding procedural steps and developing spatial awareness. Pilot integration of VR training into the curriculum demonstrated comparable training times and emphasized structured stepwise training modules to ensure completion of vital procedural steps. CONCLUSIONS: This study underscores the potential of VR simulation as a complementary training tool for CVC placement rather than a substitution of standard manikin training. VR is offering immersive experiences and addressing limitations of traditional manikin-based training methods. The integration of VR into training curricula warrants further exploration to optimize procedural proficiency and patient safety in clinical practice.

Effectiveness of Erector Spinae Plane Block as Perioperative Analgesia in Midline Sternotomies: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

ABSTRACT: With the advancements in regional anesthesia and ultrasound techniques, the use of non-neuraxial blocks like the erector spinae plane block (ESPB) has been increasing in cardiac surgeries with promising outcomes. A total of 3,264 articles were identified through a literature search. Intervention was defined as ESPB. Comparators were no regional technique performed or sham blocks. Four studies with a total of 226 patients were included. Postoperative opioid consumption was lower in the group that received ESPB than the group that did not (weighted mean difference [WMD]: -204.08; 95% CI: -239.98 to -168.19; P < 0.00001). Intraoperative opioid consumption did not differ between the two groups (WMD: -398.14; 95% CI: -812.17 to 15.98; P = 0.06). Pain scores at 0 hours were lower in the group that received ESPB than the group that did not (WMD: -1.27; 95% CI: -1.99 to -0.56; P = 0.0005). Pain scores did not differ between the two groups at 4-6 hours (WMD: -0.79; 95% CI: -1.70 to 0.13; P = 0.09) and 12 hours (WMD: -0.83; 95% CI: -1.82 to 0.16; P = 0.10). Duration of mechanical ventilation in minutes was lower in the group that received ESPB than the group that did not (WMD: -45.12; 95% CI: -68.82 to -21.43; P = 0.0002). Given the limited number of studies and the substantial heterogeneity of measured outcomes and interventions, further studies are required to assess the benefit of ESPB in midline sternotomies.

Memory-making interventions for children and their families receiving pediatric palliative or bereavement care: A systematic review protocol.

Background: In paediatric palliative and bereavement care, providing comprehensive support that extends beyond medical treatment to address the emotional and psychosocial needs of children and their families is essential. Memory-making interventions play a critical role in capturing cherished moments and fostering emotional resilience. However, widespread consensus on the foundation and scope of memory-making interventions for children and young people remains sparse. This review aims to identify, appraise, and synthesise the evidence on memory-making interventions for children and young people with life-limiting or life-threatening conditions and their family members receiving palliative or bereavement care. Methods: This systematic review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). A systematic search will be undertaken from January 1, 1985, to February 27, 2024, across the following databases: PubMed, EMBASE, CINAHL (EBSCO), PsycINFO (EBSCO), Web of Science, the Cochrane Library, and Scopus. Studies across diverse research designs that examine children (0-19 years) with life-limiting or life-threatening conditions undergoing memory-making interventions with psychosocial or other outcomes will be included. Screening, data extraction, and quality appraisal will be performed by two independent reviewers, with a third reviewer resolving discrepancies. Joanna Briggs Institute guidelines for conducting mixed methods systematic reviews will be used to inform the data analysis and synthesis process. Conclusions: This review will provide critical insights into the existing evidence base on memory-making interventions in paediatric palliative and bereavement care, highlighting psychosocial and other impacts, implementation factors, and evidence quality. By identifying best practices and gaps in knowledge, this evidence review may inform future research and intervention design, or adaptation, and contribute to the enhancement of healthcare for children and young people with life-limiting and life-threatening conditions and their families as well as families in bereavement. Registration: This review was registered in PROSPERO, the International Prospective Register of Systematic Reviews (CRD42024521388; 18/03/2024).

Strict compliance to a thoracic enhanced recovery after surgery protocol is associated with improved outcomes compared with partial compliance: A prospective cohort study.

BACKGROUND: Benefits of thoracic enhanced recovery after surgery programs have been described. However, there is ongoing discussion on the importance of full protocol compliance. The objective of this study was to determine whether strict adherence to an enhanced recovery after surgery protocol leads to further improvement in outcomes compared with less strict compliance. METHODS: This was a multihospital prospective cohort study of all consecutive anatomic lung resection patients on the thoracic enhanced recovery after surgery pathway from May 2021 to March 2023, with comparison with a historical control from January 2019 to April 2021. Compliance to 5 key protocol elements was tracked. Patients were grouped into high- and low-compliance cohorts, defined as adherence to 4-5/5 or 0-3/5 elements, respectively. The primary outcome was overall morbidity; secondary outcomes included cardiac, respiratory, and infectious morbidity and length of stay. RESULTS: Of the 960 patients, 429 (44.7%) were enhanced recovery after surgery patients and 531 (55.3%) were in the historical control group. Across all patients, 250 (26.0%) were considered high compliance and 710 (74.0%) were considered low compliance. After adjustment for enhanced recovery after surgery status and confounders, the association between high compliance and improved outcomes persisted for all but infectious morbidity. Compared with low compliance, high compliance was associated with decreased odds of any morbidity (0.41 [95% CI, 0.22-0.77]), cardiac morbidity (0.31 [0.11-0.91]), respiratory morbidity (0.46 [0.23-0.90]) and decreased length of stay (0.38 [0.18-0.87]). CONCLUSION: Enhanced recovery after surgery protocols improve outcomes after anatomic lung resection. Increasing compliance to individual elements (>80%) further improves patient outcomes. Continued efforts should be directed at increasing compliance to individual protocol elements.

Analyzing the Evolution of Needle and Ultrasound Probe Manipulation Skills of Interventional Radiology Trainees With Time and Experience.

PURPOSE: To test the hypothesis that hand motion analysis can measure the progression of needle and ultrasound probe manipulation skills of interventional radiology trainees in central venous line placement. MATERIALS AND METHODS: An expert cohort of 6 interventional radiologists and 4 anesthesiologists and a trainee cohort of 6 novice trainees (<50 central lines) and 5 experienced trainees (>50 central lines) performed simulated central venous access. Four novices and 1 experienced trainee repeated the task 1 year later. An electromagnetic motion tracking system tracked the needle hand and ultrasound probe. Path length, translational, and rotational movements were calculated separately for the needle hand and probe sensor. These metrics were used to calculate motion metrics based scores on a scale of 0 to 3 for each sensor. Nonparametric statistics were used, and the data are reported as median ± interquartile range. RESULTS: Comparing novice and experienced trainees, there was a significant difference in probe scores (experienced vs. novice: 1 ± 2 vs. 0 ± 0, P = 0.04) but not in needle-hand scores (1 ± 1.5 vs. 0 ± 1, P = 0.26). Trainees showed a significant increase in probe scores at the 1-year follow-up (baseline vs. follow-up: 0 ± 1 vs. 2.5 ± 1.8, P = 0.003), but no significant difference was observed in the needle manipulation metrics. Experts differed significantly from experienced trainees for all metrics for both sensors (P < 0.05), with the exception of the path length of the probe. CONCLUSIONS: Acquisition of improved dexterity of the probe may occur before improvement in the dexterity with the needle hand for interventional radiology trainees.

Representation of women among cardiothoracic surgery editorial boards: Trends over the past 2 decades.

OBJECTIVE: The objective of this study was to examine representation of women on the editorial boards of cardiothoracic surgery-focused journals over the past 2 decades to identify changes over time compared with women cardiothoracic surgeon and trainee representation, and to highlight additional opportunities for improvement. METHODS: The editorial boards of 2 high-impact cardiothoracic surgery journals were reviewed from 2000 to 2023. Data on editorial board positions, including editors-in-chief, associate/deputy editors, feature editors, and general members of the editorial board were abstracted. The proportion of women editors was assessed. Data were compared with publicly available information from the Association of American Medical Colleges on physician specialty by sex. RESULTS: Of 3460 editorial positions, 332 (9.6%) were held by women. Women occupied 2.2% (1 out of 45) of editor-in-chief positions, 13.2% (78 out of 592) of senior editor positions, 11.5% (33 out of 287) of feature editor positions, and 8.3% (221 out of 2663) of general editorial board positions. The proportion of women holding any editorial board position significantly increased from 2.4% in 2000 to 18.2% in 2023 (P = .01). Overall, editorial board representation increased at a rate of 0.7% ± 1.3% per year, not significantly different from the growth of practicing women cardiothoracic surgeons at 0.3% ± 0.5% per year (P = .584). DISCUSSION: Representation of women on the editorial boards of cardiothoracic surgery-focused journals has increased commensurate with the increasing proportion of practicing women cardiothoracic surgeons, although remains at 16%. Work remains to continue the recruitment of women to cardiothoracic surgery as well as to identify the key elements that can support them in positions of leadership.

Does cardiorespiratory fitness mediate or moderate the association between mid-life physical activity frequency and cognitive function? findings from the 1958 British birth cohort study.

BACKGROUND: Physical activity (PA) is associated with a lower risk of cognitive decline and all-cause dementia in later life. Pathways underpinning this association are unclear but may involve either mediation and/or moderation by cardiorespiratory fitness (CRF). METHODS: Data on PA frequency (exposure) at 42y, non-exercise testing CRF (NETCRF, mediator/moderator) at 45y and overall cognitive function (outcome) at 50y were obtained from 9,385 participants (50.8% female) in the 1958 British birth cohort study. We used a four-way decomposition approach to examine the relative contributions of mediation and moderation by NETCRF on the association between PA frequency at 42y and overall cognitive function at 50y. RESULTS: In males, the estimated overall effect of 42y PA ≥once per week (vs.

Clinical validation of C12FDG as a marker associated with senescence and osteoarthritic phenotypes.

Chronic conditions associated with aging have proven difficult to prevent or treat. Senescence is a cell fate defined by loss of proliferative capacity and the development of a pro-inflammatory senescence-associated secretory phenotype comprised of cytokines/chemokines, proteases, and other factors that promotes age-related diseases. Specifically, an increase in senescent peripheral blood mononuclear cells (PBMCs), including T cells, is associated with conditions like frailty, rheumatoid arthritis, and bone loss. However, it is unknown if the percentage of senescent PBMCs associated with age-associated orthopedic decline could be used for potential diagnostic or prognostic use in orthopedics. Here, we report senescent cell detection using the fluorescent compound C12FDG to quantify PBMCs senescence across a large cohort of healthy and osteoarthritic patients. There is an increase in the percent of circulating C12FDG+ PBMCs that is commensurate with increases in age and senescence-related serum biomarkers. Interestingly, C12FDG+ PBMCs and T cells also were found to be elevated in patients with mild to moderate osteoarthritis, a progressive joint disease that is strongly associated with inflammation. The percent of C12FDG+ PBMCs and age-related serum biomarkers were decreased in a small subgroup of study participants taking the senolytic drug fisetin. These results demonstrate quantifiable measurements in a large group of participants that could create a composite score of healthy aging sensitive enough to detect changes following senolytic therapy and may predict age-related orthopedic decline. Detection of peripheral senescence in PBMCs and subsets using C12FDG may be clinically useful for quantifying cellular senescence and determining how and if it plays a pathological role in osteoarthritic progression.

Current Advances and Material Innovations in the Search for Novel Treatments of Phenylketonuria.

Phenylketonuria (PKU) is a genetically inherited disease caused by a mutation of the gene encoding phenylalanine hydroxylase (PAH) and is the most common inborn error of amino acid metabolism. A deficiency of PAH leads to increased blood and brain levels of phenylalanine (Phe), which may cause permanent neurocognitive symptoms and developmental delays if untreated. Current management strategies for PKU consist of early detection through neonatal screening and implementation of a restrictive diet with minimal amounts of natural protein in combination with Phe-free supplements and low-protein foods to meet nutritional requirements. For milder forms of PKU, oral treatment with synthetic sapropterin (BH4), the cofactor of PAH, may improve metabolic control of Phe and allow for more natural protein to be included in the patient's diet. For more severe forms, daily injections of pegvaliase, a PEGylated variant of phenylalanine ammonia-lyase (PAL), may allow for normalization of blood Phe levels. However, the latter treatment has considerable drawbacks, notably a strong immunogenicity of the exogenous enzyme and the attached polymeric chains. Research for novel therapies of PKU makes use of innovative materials for drug delivery and state-of-the-art protein engineering techniques to develop treatments which are safer, more effective, and potentially permanent.

Allosteric activation unveils protein-mass modulation of ATP phosphoribosyltransferase product release.

Heavy-isotope substitution into enzymes slows down bond vibrations and may alter transition-state barrier crossing probability if this is coupled to fast protein motions. ATP phosphoribosyltransferase from Acinetobacter baumannii is a multi-protein complex where the regulatory protein HisZ allosterically enhances catalysis by the catalytic protein HisGS. This is accompanied by a shift in rate-limiting step from chemistry to product release. Here we report that isotope-labelling of HisGS has no effect on the nonactivated reaction, which involves negative activation heat capacity, while HisZ-activated HisGS catalytic rate decreases in a strictly mass-dependent fashion across five different HisGS masses, at low temperatures. Surprisingly, the effect is not linked to the chemical step, but to fast motions governing product release in the activated enzyme. Disruption of a specific enzyme-product interaction abolishes the isotope effects. Results highlight how altered protein mass perturbs allosterically modulated thermal motions relevant to the catalytic cycle beyond the chemical step.

Use of marine occurrent extracts to enhance the stability of dentin extracellular matrix.

Chitosan (CS) and phloroglucinol (PhG), two extracts abundantly found in marine life, were investigated for their ability to biomodify demineralized dentin by enhancing collagen crosslinks and improving dentin extracellular matrix (ECM) mechanical and biochemical stability. Dentin obtained from non-carious extracted human molars were demineralized with phosphoric acid. Baseline Fourier-transform infrared (FTIR) spectra, apparent flexural elastic modulus (AE) and dry mass (DM) of each specimen were independently acquired. Specimens were randomly incubated for 5 min into either ultrapure water (no-treatment), 1% glutaraldehyde (GA), 1% CS or 1% PhG. Water and GA were used, respectively, as a negative and positive control for collagen crosslinks. Specimens' post-treatment FTIR spectra, AE, and DM were obtained and compared with correspondent baseline measurements. Additionally, the host-derived proteolytic activity of dentin ECM was assessed using hydroxyproline assay (HYP) and spectrofluorometric analysis of a fluorescent-quenched substrate specific for matrix metalloproteinases (MMPs). Finally, the bond strength of an etch-and-rinse adhesive was evaluated after application of marine compounds as non-rinsing dentin primers. Dentin specimens FTIR spectral profile changed remarkably, and their AE increased significantly after treatment with marine compounds. DM variation, HYP assay and fluorogenic substrate analysis concurrently indicated the biodegradation of CS- and PhG-treated specimens was significantly lesser in comparison with untreated specimens. CS and PhG treatments enhanced biomechanical/biochemical stability of demineralized dentin. These novel results show that PhG is a primer with the capacity to biomodify demineralized dentin, hence rendering it less susceptible to biodegradation by host-proteases.