Biomechanical, Histologic, and Micro-Computed Tomography Characterization of Partial-Width Full-Thickness Supraspinatus Tendon Injury in Rats.

PURPOSE: Partial rotator cuff tears can cause shoulder pain and dysfunction and are more common than complete tears. However, few studies examine partial injuries in small animals and, therefore a robust, clinically relevant model may be lacking. This study aimed to fully characterize the established rat model of partial rotator cuff injury over time and determine if it models human partial rotator cuff tears. METHODS: We created a full-thickness, partial-width injury at the supraspinatus tendon-bone interface bilaterally in 31 Sprague-Dawley rats. Rats were euthanized immediately, and at 2-, 3-, 4-, and 8-weeks after surgery. Fourteen intact shoulders were used as controls. Samples were assessed biomechanically, histologically, and morphologically. RESULTS: Biomechanically, load to failure in controls and 8 weeks after injury was significantly greater than immediately and 3 weeks after injury. Load to failure at 8 weeks was comparable to control. However, the locations of failure were different between intact shoulders and partially injured samples. Bone mineral density at 8 weeks was significantly greater than that at 2 and 3 weeks. Although no animals demonstrated propagation to complete tear and the injury site remodeled histologically, the appearance at 8 weeks was not identical to that in the controls. CONCLUSIONS: The biomechanical properties and bone quality decreased after the injury and was restored gradually over time with full restoration by 8 weeks after injury. However, the findings were not equivalent to the intact shoulder. This study demonstrated the limitations of the current model in its application to long-term outcome studies, and the need for better models that can be used to assess chronic partial rotator cuff injuries. CLINICAL RELEVANCE: There is no small animal model that mimics human chronic partial rotator cuff tears, which limits our ability to improve care for this common condition.

A zeolite family with expanding structural complexity and embedded isoreticular structures.

The prediction and synthesis of new crystal structures enable the targeted preparation of materials with desired properties. Among porous solids, this has been achieved for metal-organic frameworks, but not for the more widely applicable zeolites, where new materials are usually discovered using exploratory synthesis. Although millions of hypothetical zeolite structures have been proposed, not enough is known about their synthesis mechanism to allow any given structure to be prepared. Here we present an approach that combines structure solution with structure prediction, and inspires the targeted synthesis of new super-complex zeolites. We used electron diffraction to identify a family of related structures and to discover the structural 'coding' within them. This allowed us to determine the complex, and previously unknown, structure of zeolite ZSM-25 (ref. 8), which has the largest unit-cell volume of all known zeolites (91,554 cubic ångströms) and demonstrates selective CO2 adsorption. By extending our method, we were able to predict other members of a family of increasingly complex, but structurally related, zeolites and to synthesize two more-complex zeolites in the family, PST-20 and PST-25, with much larger cell volumes (166,988 and 275,178 cubic ångströms, respectively) and similar selective adsorption properties. Members of this family have the same symmetry, but an expanding unit cell, and are related by hitherto unrecognized structural principles; we call these family members embedded isoreticular zeolite structures.

The Origin of Selective Adsorption of CO2 on Merlinoite Zeolites.

The CO2 adsorption behavior at 25-75 °C and 0-1.0 bar of various alkali cation-exchanged forms of merlinoite (framework type MER) zeolites with Si/Al=2.3 and 3.8 is described. The adsorption isotherms at 25 °C on the Na+ , K+ , Rb+ , and Cs+ forms of MER zeolite with Si/Al=2.3 are characterized by a clear step, the CO2 pressure of which differs notably according to the type of their extraframework cations. Structural analysis shows that CO2 adsorption on the former three zeolites includes the relocation of gating cations with high site occupancy and the remarkable concomitant structural breathing. We define this unusual adsorption phenomenon as a cooperative cation gating-breathing mechanism. The overall results suggest that the actual mechanism of selective CO2 adsorption on intermediate-silica small-pore zeolites can change from cation gating to cooperative cation gating-breathing to breathing, depending on a combination of their topological and compositional flexibilities.

Topical Antibiotic Elution in a Collagen-Rich Hydrogel Successfully Inhibits Bacterial Growth and Biofilm Formation In Vitro.

Chronic wounds are a prominent concern, accounting for $25 billion of health care costs annually. Biofilms have been implicated in delayed wound closure, but they are susceptible to developing antibiotic resistance and treatment options continue to be limited. A novel collagen-rich hydrogel derived from human extracellular matrix presents an avenue for treating chronic wounds by providing appropriate extracellular proteins for healing and promoting neovascularization. Using the hydrogel as a delivery system for localized secretion of a therapeutic dosage of antibiotics presents an attractive means of maximizing delivery while minimizing systemic side effects. We hypothesize that the hydrogel can provide controlled elution of antibiotics leading to inhibition of bacterial growth and disruption of biofilm formation. The rate of antibiotic elution from the collagen-rich hydrogel and the efficacy of biofilm disruption was assessed with Pseudomonas aeruginosa Bacterial growth inhibition, biofilm disruption, and mammalian cell cytotoxicity were quantified using in vitro models. The antibiotic-loaded hydrogel showed sustained release of antibiotics for up to 24 h at therapeutic levels. The treatment inhibited bacterial growth and disrupted biofilm formation at multiple time points. The hydrogel was capable of accommodating various classes of antibiotics and did not result in cytotoxicity in mammalian fibroblasts or adipose stem cells. The antibiotic-loaded collagen-rich hydrogel is capable of controlled antibiotic release effective for bacteria cell death without native cell death. A human-derived hydrogel that is capable of eluting therapeutic levels of antibiotic is an exciting prospect in the field of chronic wound healing.

Descriptive Overview of Primary Cleft Palate Surgeries in the Low- and Middle-Income Countries.

OBJECTIVE: To increase access to high-quality and multiregional databases in global epidemiology of cleft surgeries through partnership with an NGO. DESIGN: The study retrospectively analyzes 34 801 primary palate surgeries in 70+ countries from the 2016 electronic health records of an non-governmental organization (NGO). The study also utilizes the Kids' Inpatient Database to compare the epidemiology of primary cleft palate surgeries in the United States. PARTICIPANTS: Patient records of those undergoing primary cleft palate surgeries only. MAIN OUTCOME MEASURES: Region, age, sex, type of cleft, laterality of cleft. RESULTS: Key findings show that average age of those receiving primary cleft palate surgery in the low- and middle-income countries (LMICs) was 1.95 years. The distribution of males and females receiving surgery corresponds to the US national data. More hard cleft palates were on the left side (66.18%) than the right side (33.82%), independent of gender and region. CONCLUSIONS: Databases from an established NGO can be used to enhance our understanding of the disease characteristics in these regions. By increasing the information available regarding cleft surgeries in the LMIC, we hope to increase awareness of the similarities and differences in surgeries across various regions, as part of an effort to inform the goals set by Global Surgery 2030 initiative by the Lancet Commission.

A Novel Technology for Free Flap Monitoring: Pilot Study of a Wireless, Biodegradable Sensor.

BACKGROUND: Accurate monitoring of free flap perfusion after complex reconstruction is critical for early recognition of flap compromise. Surgeons use a variety of subjective and objective measures to evaluate flap perfusion postoperatively. However, these measures have some limitations. We have developed a wireless, biodegradable, and flexible sensor that can be applied to real-time postoperative free flap monitoring. Here we assess the biocompatibility and function of our novel sensor. METHODS: Seven Sprague-Dawley (SD) rats were used for biocompatibility studies. The sensor was implanted around the femoral artery near the inguinal ligament on one leg (implant side) and sham surgery was performed on the contralateral leg (control side). At 6 and 12 weeks, samples were harvested to assess the inflammation within and around the implant and artery. Two animals were used to assess sensor function. Sensor function was evaluated at implantation and 7 days after the implantation. Signal changes after venous occlusion were also assessed in an epigastric artery island flap model. RESULTS: In biocompatibility studies, the diameter of the arterial lumen and intima thickness in the implant group were not significantly different than the control group at the 12-week time point. The number of CD-68 positive cells that infiltrated into the soft tissue, surrounding the femoral artery, was also not significantly different between groups at the 12-week time point. For sensor function, accurate signaling could be recorded at implantation and 7 days later. A change in arterial signal was noted immediately after venous occlusion in a flap model. CONCLUSION: The novel wireless, biodegradable sensor presented here is biocompatible and capable of detecting arterial blood flow and venous occlusion with high sensitivity. This promising new technology could combat the complications of wired sensors, while improving the survival rate of flaps with vessel compromise due to its responsive nature.

Effect of Head Rotation on Jugular Vein Patency Under General Anesthesia.

Head rotation causes compression and occlusion of the ipsilateral internal jugular (IJ) vein. This can result in raised intracranial pressure and increased bleeding if the patient is having or has recently had surgery. The amount of head rotation in adults resulting in occlusion of the ipsilateral IJ vein is unknown however. We measured the amount of head turn that produced occlusion of the ipsilateral IJ vein in 25 patients having surgery under general anesthesia. On average, 80% of IJ veins occlude at a mean of 55.6° on the left and 53.3° on the right.

Influence of Flexibility on the Separation of Chiral Isomers in STW-Type Zeolite.

Molecular simulation, through the computation of adsorption isotherms, is a useful predictive tool for the selective capacity of nanoporous materials. Generally, adsorbents are modelled as rigid frameworks, as opposed to allowing for vibrations of the lattice, and this approximation is assumed to have negligible impact on adsorption. In this work, this approach was tested in an especially challenging system by computing the adsorption of the chiral molecules 2-pentanol, 2-methylbutanol and 3-methyl-2-butanol in the all-silica and germanosilicate chiral zeolites STW and studying their lattice vibrations upon adsorption. The analysis of single- and multicomponent adsorption isotherms showed the suitability of STW-type zeolites as molecular sieves for chiral separation processes, which pose a challenging task in the chemical and pharmaceutical industries. Moreover, new experimental adsorption data validate the force field employed. The results reveal that the lattice vibrations of the all-silica framework are sorbate-independent, while those of germanosilicate STW show host-guest coupling modulated by uptake and sorbate type that disrupts the chiral recognition sites. This study indicates that the effects of intrinsic flexibility on the selective capacity of nanoporous materials may range from low to high impact, and some of them could not have been foreseen even after examination of the structural dynamics of an empty framework.

Stepped Propane Adsorption in Pure-Silica ITW Zeolite.

Gas adsorption over zeolites is at the basis of important applications of this class of microporous crystalline solids, notably as separation media and catalysts, but it may also be complex and not straightforward to understand. Here we report that for temperature below 323 K propane adsorption on the small-pore pure-silica zeolite ITW exhibits a clear step (pseudosaturation). This is absent in the case of propene and the other small linear alkanes. An intermediate plateau, clearly observed in the 293 K isotherm, always occurs when one molecule of propane is loaded in every other cage, i.e., at half-saturation. The simulation results show a swelling of the ITW structure upon propane adsorption. The strong dependence of available pore volume on the adsorbate loading level implies that adsorption cannot occur on the void structure while saturation can only be reached on highly loaded structures. To account for this unprecedented adsorption phenomenon, we propose the term "guest-modulated effect".

Targeted Synthesis of Two Super-Complex Zeolites with Embedded Isoreticular Structures.

A novel structural coding approach combining structure solution, prediction, and the targeted synthesis of new zeolites with expanding complexity and embedded isoreticular structures was recently proposed. Using this approach, the structures of two new zeolites in the RHO family, PST-20 and PST-25, were predicted and synthesized. Herein, by extending this approach, the next two higher generation members of this family, PST-26 and PST-28, have been predicted and synthesized. These two zeolites have much larger unit cell volumes (422,655 Å(3) and 614,912 Å(3), respectively) than those of the lower generations. Their crystallization was confirmed by a combination of both powder X-ray and electron diffraction techniques. Aluminate and water concentrations in the synthetic mixture were found to be the two most critical factors influencing the structural expansion of embedded isoreticular zeolites under the synthetic conditions studied herein.

Assessment of a Synergistic Effect of Platelet-Rich Plasma and Stem Cell-Seeded Hydrogel for Healing of Rat Chronic Rotator Cuff Injuries.

Outcomes after repair of chronic rotator cuff injuries remain suboptimal. Type-1 collagen-rich tendon hydrogel was previously reported to improve healing in a rat chronic rotator cuff injury model. Stem cell seeding of the tendon hydrogel improved bone quality in the same model. This study aimed to examine whether there was a synergistic and dose-dependent effect of platelet-rich plasma (PRP) on tendon-bone interface healing by combining PRP with stem cell-seeded tendon hydrogel. Human cadaveric tendons were processed into a hydrogel. PRP was prepared at two different platelet concentrations: an initial concentration (initial PRP group) and a higher concentration (concentrated PRP group). Tendon hydrogel was mixed with adipose-derived stem cells and one of the platelet concentrations. Methylcellulose, as opposed to saline, was used as a negative control due to comparable viscosity. The supraspinatus tendon was detached bilaterally in 33 Sprague-Dawley rats (66 shoulders). Eight weeks later, each detached tendon was repaired, and a hydrogel mixture or control was injected at the repair site. Eight weeks after repair, shoulder samples were harvested and assigned for biomechanical testing (n = 42 shoulders) or a combination of bone morphological and histological assessment (n = 24 shoulders). Biomechanical testing showed significantly higher failure load and stiffness in the concentrated PRP group than in control. Yield load in the initial and concentrated PRP groups were significantly higher than that in the control. There were no statistically significant differences between the initial and concentrated PRP groups. The addition of the highly concentrated PRP to stem cells-seeded tendon hydrogel improved healing biomechanically after chronic rotator cuff injury in rats compared to control. However, synergistic and dose-dependent effects were not seen.

An intrinsic synthesis parameter governing the crystallization of silico(zinco)aluminophosphate molecular sieves.

One of the most fundamental but yet unanswered questions in the synthesis of zeolites and zeolite-like materials is whether or not any parameter controlling the microporosity of the crystallized product from synthesis mixtures with feasible chemical compositions exists. Here we report that an experimentally optimized parameter (ca. 3.3 ≤ MOH/P2O5 ≤ 5.3, where M is alkali metal ions) is the criterion bringing about the successful formation of various high-charge-density silicoaluminophosphate (SAPO) and zincoaluminophosphate (ZnAPO) molecular sieves, without the aid of organic structure-directing agents. The materials obtained using this empirical concept include SAPO molecular sieves with CHA and LTA topologies, as well as a SAPO FAU/EMT intergrowth, and ZnAPO ones with CZP and SOD topologies. This study demonstrates the existence of an essential factor determining not only phase selectivity but also microporosity (0.3-2 nm) in the synthesis of zeotypes with charged frameworks which may offer interesting opportunities for more efficiently producing novel zeolite structures and/or compositions.

Efficacy of intercostal cryoneurolysis as an analgesic adjunct for chest wall pain after surgery or trauma: systematic review.

BACKGROUND: There is a critical need for non-narcotic analgesic adjuncts in the treatment of thoracic pain. We evaluated the efficacy of intercostal cryoneurolysis as an analgesic adjunct for chest wall pain, specifically addressing the applicability of intercostal cryoneurolysis for pain control after chest wall trauma. METHODS: A systematic review was performed through searches of PubMed, EMBASE, and the Cochrane Library. We included studies involving patients of all ages that evaluated the efficacy of intercostal cryoneurolysis as a pain adjunct for chest wall pathology. Quantitative and qualitative synthesis was performed. RESULTS: Twenty-three studies including 570 patients undergoing cryoneurolysis met eligibility criteria for quantitative analysis. Five subgroups of patients treated with intercostal cryoneurolysis were identified: pectus excavatum (nine studies); thoracotomy (eight studies); post-thoracotomy pain syndrome (three studies); malignant chest wall pain (two studies); and traumatic rib fractures (one study). There is overall low-quality evidence supporting intercostal cryoneurolysis as an analgesic adjunct for chest wall pain. A majority of studies demonstrated decreased inpatient narcotic use with intercostal cryoneurolysis compared with conventional pain modalities. Intercostal cryoneurolysis may also lead to decreased hospital length of stay. The procedure did not definitively increase operative time, and risk of complications was low. CONCLUSIONS: Given the favorable risk-to-benefit profile, both percutaneous and thoracoscopic intercostal cryoneurolysis may serve as a worthwhile analgesic adjunct in trauma patients with rib fractures who have failed conventional medical management. However, further prospective studies are needed to improve quality of evidence. LEVEL OF EVIDENCE: Level IV systematic reviews and meta-analyses.

Intercostal nerve cryoablation during surgical stabilization of rib fractures.

BACKGROUND: Intercostal nerve cryoablation (IC) offers potential for targeted and durable analgesia for patients with traumatic rib fractures. Our pilot study aimed to investigate thoracoscopic IC's safety, feasibility, and preliminary efficacy for patients undergoing surgical stabilization of rib fractures (SSRF). We hypothesized that concurrent surgical stabilization of rib fractures and intercostal nerve cryoablation (SSRF-IC) is a safe and feasible procedure without immediate or long-term complications. METHODS: We retrospectively evaluated patients 18 years or older who underwent SSRF (with or without IC) for acute rib fractures at our level I trauma center between September 1, 2019, and September 30, 2020. We performed IC under thoracoscopic visualization (-70°C for 2 minutes per intercostal nerve bundle). Among patients whose only operative procedure during hospitalization was SSRF, we evaluated post-SSRF length of stay, operative times, opioid requirements (oral morphine equivalents), and pain scores (Numerical Rating Scale). Generalized estimating equations compared SSRF and SSRF-IC group outcomes (population mean [robust standard error]). We assessed long-term outcomes of patients who underwent SSRF-IC. RESULTS: Thirty-four patients (144 ribs) underwent SSRF; of these, 20 patients (135 ribs) underwent SSRF-IC. Patients who did and did not undergo concurrent IC had no significant difference demographic, injury, or hospitalization characteristics. Among 20 patients who did not undergo other operations, 12 underwent SSRF-IC. We did not find significant difference between SSRF and SSRF-IC groups' median operative times or post-SSRF length of stay. Compared with SSRF group, SSRF-IC group did not have statistically significant change in pain score (0.2 [1.5] lower) or opioid use (43.9 [86.1] mg/d greater) between 12 hours before SSRF and last 24 admission hours. Among 17 SSRF-IC patients who followed-up postdischarge (median [range], 160 [9-357] days), one reported mild chest wall paresthesia; no other complications were reported. CONCLUSION: This pilot study performing 135 intercostal nerve cryoablations on 20 patients suggests that IC is safe and feasible for patients undergoing SSRF. Evaluating IC's analgesic efficacy for rib fractures requires further study. LEVEL OF EVIDENCE: Therapeutic, Level V.

Scoping review of traumatic hemothorax: Evidence and knowledge gaps, from diagnosis to chest tube removal.

BACKGROUND: Traumatic hemothorax is a common injury that invites diagnostic and management strategy debates. Evidence-based management has been associated with improved care efficiency. However, the literature abounds with long-debated, re-emerging, and new questions. We aimed to consolidate up-to-date evidence on traumatic hemothoraces, focusing on clinical conundra debated in literature. METHODS: We conducted a scoping review of 21 clinical conundra in traumatic hemothorax diagnosis and management according to PRISMA-ScR guidelines. Experimental and observational studies evaluating patients (aged ≥18 years) with traumatic hemothoraces were identified through database searches (PubMed, EMBASE, Web of Science, Cochrane Library; database inception to Sep, 26 2020) and bibliography reviews of selected articles. Three reviewers screened and selected articles using standardized forms. RESULTS: We screened 1,440 articles for eligibility, of which 71 met criteria for synthesis. The review comprises 6 sections: (1) Presumptive antibiotics before tube thoracostomy; (2) Initial diagnostic and intervention decisions; (3) Chest tubes; (4) Retained hemothoraces; (5) Delayed hemothoraces; and (6) Chest tube removal). The 21 conundra across these sections follow the format of a question, our recommendation based on interpretation of available evidence, and succinct rationale. Rationale sections detail knowledge gaps and opportunities for future research. CONCLUSION: Even practices engrained into surgical dogma, such as obtaining chest x-rays after inserting or removing chest tubes and mandating operation for patients who develop chest tube output above a certain threshold, deserve re-evaluation. Some knowledge gaps require rigorous future investigation; sound clinical judgment can likely supplement others.

Intraoperative Transcranial Motor-evoked Potential Stimulation Does Not Seem to Cause Seizures.

BACKGROUND: Intraoperative neurophysiological monitoring is of critical importance in evaluating the functional integrity of the central nervous system during surgery of the central or peripheral nervous system. In a large recent study, transcranial motor-evoked potentials (TcMEPs) were found to be associated with a 0.7% risk of inducing a seizure as diagnosed by clinical observation and electromyography in patients having general anesthesia with intravenous anesthetics. The gold standard for seizure diagnosis, however, is electroencephalography (EEG). The aim of this single-institution retrospective study is to ascertain the risk of intraoperative seizures detected using EEG during surgeries in adult patients undergoing intraoperative monitoring with TcMEPs. METHODS: The authors retrospectively reviewed the intraoperative EEG records of 1175 patients anesthetized with a variety of anesthetic agents, including volatile and intravenous anesthetics, to ascertain the rate of EEG-diagnosed seizures attributable to TcMEPs. RESULT: Our analysis did not reveal a single seizure event attributable to TcMEPs in 1175 patients. CONCLUSION: The intraoperative use of TcMEPs does not seem to cause seizures.

Continued nursing education in low-income and middle-income countries: a narrative synthesis.

Introduction: Continued nursing education and development can reduce mortality and morbidity of patients and can alleviate the shortage of healthcare workers by training of nurses for high-demand skill sets. We reviewed patterns of educational interventions and strategies in initiating behaviour change, improving patient outcomes or knowledge for nurses in low- and middle-income countries (LMICs). Methods: The study searched the MEDLINE (PubMed), Embase, CINAHL, Google Scholar and Web of Science databases. The study included interventional studies on continued nursing education from 2007 to 2017. Of the 6216 publications retrieved, 98 articles were included and analysed by three independent reviewers. Results: Of the 98 studies that met inclusion criteria, five were randomised controlled trials, two were qualitative in design and the remaining 91 were quasi-experimental, before-and-after studies. Of these studies, the median sample size of participants was 64, and the majority were conducted in Asia (53.1%). During the 10-year study period, 20.4% was conducted in 2015, the highest proportion, with a general increase in number of studies over time from 2007 to 2017. Main themes that arose from the review included train-the-trainer models, low-dose/high-frequency models, use of multiple media for training, and emphasis on nurse empowerment, strong international partnerships, and the integration of cultural context. Overall, the studies were limited in quality and lacked rigorous study design. Conclusion: Continued nursing education in LMICs is essential and effective in improving nurses' knowledge base, and thus patient outcomes and quality of care. Long-term, randomised studies are needed to understand how training strategies compare in impact on nurses and patients.

Colloidal Porous AuAg Alloyed Nanoparticles for Enhanced Photoacoustic Imaging.

Colloidal porous AuAg alloyed nanoparticles (pAuAgNPs) were synthesized by galvanic replacement reaction from Ag nanocubes. pAuAgNPs have a 50 nm exterior diameter and half of their inner space consists of voids that have a bimodal size distribution with peaks at 21 and 8.3 nm. pAuAgNPs showed a plasmonic peak at 750 nm, which was exploited for photoacoustic (PA) imaging. Gold nanorods (AuNRs) were prepared and used as the control; they have a strong plasmonic peak at 720 nm. In in vitro experiments at respective plasmonic peak excitations, pAuAgNPs gave stronger PA signals than AuNRs by 8.9 times per particle and 11.7 times per dosage by exogenous atom. The high surface area per volume as a result of the inner voids amplified the PA signals by efficient thermoacoustic conversion. In experiments of chicken-tissue phantoms, pAuAgNPs showed PA signals through 4.5 cm thick tissue, whereas AuNRs gave no detectable signal. In whole-body in vivo experiments, pAuAgNPs injected into the body showed 2.7 times stronger PA signals than AuNRs. Coating the pAuAgNPs with a silica layer additionally increased their PA signal by 1.8 times when compared to the uncoated ones.