Effects of antimicrobial peptides on membrane dynamics: A comparison of fluorescence and NMR experiments.

Antimicrobial peptides (AMPs) represent a promising class of compounds to fight resistant infections. They are commonly thought to kill bacteria by perturbing the permeability of their cell membranes. However, bacterial killing requires a high coverage of the cell surface by bound peptides, at least in the case of cationic and amphipathic AMPs. Therefore, it is conceivable that peptide accumulation on the bacterial membranes might interfere with vital cellular functions also by perturbing bilayer dynamics, a hypothesis that has been termed "sand in the gearbox". Here we performed a systematic study of such possible effects, for two representative peptides (the cationic cathelicidin PMAP-23 and the peptaibol alamethicin), employing fluorescence and NMR spectroscopies. These approaches are commonly applied to characterize lipid order and dynamics, but sample different time-scales and could thus report on different membrane properties. In our case, fluorescence anisotropy measurements on liposomes labelled with probes localized at different depths in the bilayer showed that both peptides perturb membrane fluidity and order. Pyrene excimer-formation experiments showed a peptide-induced reduction in lipid lateral mobility. Finally, laurdan fluorescence indicated that peptide binding reduces water penetration below the headgroups region. Comparable effects were observed also in fluorescence experiments performed directly on live bacterial cells. By contrast, the fatty acyl chain order parameters detected by deuterium NMR spectroscopy remained virtually unaffected by addition of the peptides. The apparent discrepancy between the two techniques confirms previous sporadic observations and is discussed in terms of the different characteristic times of the two approaches. The perturbation of membrane dynamics in the ns timescale, indicated by the multiple fluorescence approaches reported here, could contribute to the antimicrobial activity of AMPs, by affecting the function of membrane proteins, which is strongly dependent on the physicochemical properties of the bilayer.

A BMI above 30 results in satisfying outcomes in patients undergoing fixed-bearing lateral unicompartmental knee arthroplasty.

PURPOSE: The purpose of this study is to analyse the effect of BMI on clinical outcomes of cemented fixed-bearing lateral unicompartmental knee arthroplasty (UKA) on a 2- to 12-year follow-up. METHODS: Between January 2010 and January 2020, a total of 103 lateral UKAs were implanted. The Oxford Knee Score (OKS) and the Western Ontario and McMaster University Osteoarthritis Index for pain, stiffness, function, and total score were administered to estimate patients' overall health status pre- and post-operatively. Results were considered good or excellent for WOMAC values > 85 points and OKS > 40 points. Survivorship, described with Kaplan-Meier method, was defined as the lack of revision at the latest follow-up. Complications or further operations were recorded. p values of < 0.05 were considered significant. RESULTS: One hundred one lateral UKAs were assessed at a mean follow-up of 77.8 months. No patients underwent revision, but 2 patients (2, 0%) developed aseptic loosening of the implant 2 and 5 years after surgery but for clinical reasons neither undergo revision (5-year survivor 97.2%). Overall satisfaction was generally high, with excellent scores in all WOMAC subscales and OKS for all BMI groups. Considering the pain subscale (WOMAC pain), patients with normal weight and overweight achieve excellent results more frequently [10 (25.64%) vs 10 (23.81%) p = 0.026] than obese patients (n = 0); on the other hand, considering the quality of life (WOMAC QoL), obese patients most frequently reach excellent values, even statistically significant [n = 15 (75.00%) p = 0.040]. CONCLUSION: Although obesity has historically been described as a contraindication to UKA, improved outcomes with modern UKA implant designs have challenged this perception. Therefore, the classic contraindication of UKAs in patients with BMI > 30 kg/m2 may not be justified. According to the present study, lateral UKA patients with BMI > 30 kg/m2 had satisfactory patient-reported outcome measures compared to non-obese patients on a long term with survival rates comparable to medial UKA. Obese patients should not be excluded from the benefit of lateral UKA surgery.

Increased Time to Surgery After Anterior Cruciate Ligament Tear in Female Patients Results in Greater Risk of Medial Meniscus Tear: A Study of 489 Female Patients.

PURPOSE: This study assessed the incidence of meniscal tears in anterior cruciate ligament (ACL)-deficient knees, considering the time between injury and reconstruction in a large sample of female patients. Furthermore, we evaluated whether the rate of meniscal repair or meniscectomy was affected by age and body mass index (BMI). METHODS: The medical records of 489 patients who underwent ACL-reconstructive surgery between January 2011 and April 2021 were analyzed to collect data on the prevalence of meniscal tears, surgical timing, patient age, and BMI. Logistic regression was performed to estimate the association between the prevalence of meniscal tears and the independent variables of surgical timing, age, and BMI. RESULTS: Between 24 and 60 months after their injury, female patients showed a statistically significant increase in the presence of associated meniscal lesions when compared with ACL reconstruction performed earlier (odds ratio [OR] of 3.11; 95% 1.06-9.10 confidence interval [CI]), especially for medial meniscal tears, with an OR of 1.94 (95% CI 1.23-3.05, P = .004) between 12 and 24 months. There is a statistically significant difference after 12 months in the rate of meniscal suturing for medial meniscus tears (OR 3.30; CI 1.37-7.91 P = .007). Increasing age was associated with a greater prevalence of meniscal tears up to 30-50 years, but there was no clear association between BMI and associated lesions other than a greater rate of meniscectomies. CONCLUSIONS: In female patients who experienced an ACL injury, a delay in surgery greater than 12 months is associated with a gradual increase in the risk of nonrepairable medial meniscal tear; this risk becomes statistically significant after 24 months. A high BMI does not seem to have relevance in the onset of associated lesions in women but results in a greater rate of meniscectomies compared with meniscal sutures, whereas age between 30 and 50 years is associated with a greater risk of associated injuries. LEVEL OF EVIDENCE: III, retrospective comparative prognostic trial.

Short-term results of intra-articular injections of stromal vascular fraction for early knee osteoarthritis.

BACKGROUND: In knee osteoarthritis, progressive degeneration of the articular cartilage surface produces disability and chronic pain. Intra-articular injections of stromal vascular fraction (SVF) could be an innovative approach to manage patients with early knee osteoarthritis. METHODS: Between June 2019 and November 2020, 123 patients were recruited to receive intra-articular injection of SVF. Radiographic evidence of degenerative joint disease was classified according to Kellgren and Lawrence grades. Knee injury and osteoarthritis outcome score (KOOS) and visual analog scale (VAS) were collected preoperatively, at 1 month, and after 6 months from injection. RESULTS: There was a statistically significant improvement of KOOS and VAS of all patients to 6 months (p < 0.05). The mean KOOS before injection was 51.4 ± 16.5, after 1 month it was 75.5 ± 15.8, and at 6 months it was 87.6 ± 7.7. Stratifying the mean KOOS according to Kellgren-Lawrence Grades, the difference remained statistically significant (p < 0.05). The patients' mean VAS before injection was 6.5, after 1 month it was 3.5, and after 6 months it was 2.4. No complications were observed. CONCLUSIONS: Intra-articular knee injection of SVF is safe and effective to ameliorate the clinical and functional scores in patients with early knee osteoarthritis for 6 months.

Prolotherapy for chronic low back pain: a review of literature.

INTRODUCTION: Low back pain is common and imposes major societal burdens for patient suffering and costs. Prolotherapy injections are used for musculoskeletal conditions including tendinopathies, osteoarthritis and low back pain to enhance soft-tissue healing. This review aims to clarify the place of prolotherapy in chronic low back pain (CLBP). SOURCES OF DATA: Using multiple databases, a systematic search was performed to identify studies detailing the use of prolotherapy to manage CLBP. A total of 12 articles was included in the present work. AREAS OF AGREEMENT: Considering the level of evidence and the quality of the studies assessed using the modified Coleman Score, prolotherapy is an effective management modality for CLBP patients in whom conservative therapies failed. AREAS OF CONTROVERSY: The presence of co-interventions and the clinical heterogeneity of the work contributes to confound the overall conclusions. GROWING POINTS AND AREAS FOR RESEARCH: The analysis of the studies included in the review, using appropriate tools, showed how their quality has decreased over the years, reflecting the need for appropriately powered well planned and performed randomized control trials.

Impact of Covid-19 on undergraduate and residency training.

BACKGROUND: The covid-19 pandemic has dramatically changed lives of residents and medical students. In particular, the learning process has undergone widely changes, especially due to the rules of social distancing which have forced universities and various institutes to modify lessons, work shifts and internships. PURPOSE: The purpose of our review is to evaluate how the various institutes have faced the covid-19 emergency and guaranteed the perpetuation of the learning process of resident and students. METHODS: A comprehensive search of the medical literature in PubMed and Google Scholar was performed including all the works explaining how the institutes have reorganized teaching for resident and undergraduate students. MAIN FINDINGS: The use of internet for the dissemination of teaching material and educational meetings has built bridges, albeit virtual, between resident and teachers. New techniques for teaching and conducting exams have been introduced. The rotating team system allowed the continuation of the teaching activity in safety. CONCLUSION: Thanks to remodulation of the teach modalities, the massive use of internet platforms, a wise distribution of work shifts, and others, universities and hospitals have not only reduced the impact on the learning process of resident and students but also turn this pandemic into a moment of personal and professional growth for the new generation of healthcare professionals.

Therapeutic potential of microRNA in tendon injuries.

INTRODUCTION: The regulatory role of microRNA (miRNA) in several conditions has been studied, but their function in tendon healing remains elusive. This review summarizes how miRNAs are related to the pathogenesis of tendon injuries and highlights their clinical potential, focusing on the issues related to their delivery for clinical purposes. SOURCES OF DATA: We searched multiple databases to perform a systematic review on miRNA in relation to tendon injuries. We included in the present work a total of 15 articles. AREAS OF AGREEMENT: The mechanism of repair of tendon injuries is probably mediated by resident tenocytes. These maintain a fine equilibrium between anabolic and catabolic events of the extracellular matrix. Specific miRNAs regulate cytokine expression and orchestrate proliferation and differentiation of stromal cell lines involved in the composition of the extracellular matrix. AREAS OF CONTROVERSY: The lack of effective delivery systems poses serious obstacles to the clinical translation of these basic science findings. GROWING POINT: In vivo studies should be planned to better explore the relationship between miRNA and tendon injuries and evaluate the most suitable delivery system for these molecules. AREAS TIMELY FOR DEVELOPING RESEARCH: Investigations ex vivo suggest therapeutic opportunities of miRNA for the management of tendon injuries. Given the poor pharmacokinetic properties of miRNAs, these must be delivered by an adequate adjuvant transport system.

The temporal effect of intra-articular ozone injections on pain in knee osteoarthritis.

BACKGROUND: Osteoarthritis (OA) is a most common orthopaedic condition, often complicated by inflammatory features. SOURCES OF DATA: A systematic search in PubMed, Embase, Google Scholar and Scopus databases (to January 2019) was performed to define the effect obtained in patients with OA of the knee by injections of ozone, on pain and physical function. Six RCTs and 353 patients were included. AREAS OF AGREEMENT: Recently, an increasing number of physicians have used ozone therapy to alleviate the symptoms of acute and chronic OA of the knee. Ozone can allow greater mobility of the knee joint, pain relief and decrease in effusion. AREAS OF CONTROVERSY: The volume and concentration of ozone injected are different in the various treatment protocols published. GROWING POINTS: The action of ozone is unclear, but it is a promising therapeutic modality capable of impacting, favourably, function and quality of life. AREAS TIMELY FOR DEVELOPING RESEARCH: The lack of a clear protocol of use is a major limitation, and to date there is no clear evidence of long-term efficacy.

The presence of residents during orthopedic operation exerts no negative influence on outcome.

BACKGROUND: Operative procedural training is a key component of orthopedic surgery residency. It is unclear how and whether residents participation in orthopedic surgical procedures impacts on post-operative outcomes. SOURCES OF DATA: A systematic search was performed to identify articles in which the presence of a resident in the operating room was certified, and was compared with interventions without the presence of residents. AREAS OF AGREEMENT: There is a likely beneficial role of residents in the operating room, and there is only a weak association between the presence of a resident and a worse outcome for orthopedic surgical patients. AREAS OF CONTROVERSY: Most of the studies were undertaken in USA, and this represents a limit from the point of view of comparison with other academic and clinical realities. GROWING POINT: The data provide support for continued and perhaps increased involvement of resident in orthopedic surgery. AREAS OF RESEARCH: To clarify the role of residents on clinically relevant outcomes in orthopedic patients, appropriately powered randomized control trials should be planned.

[Digoxin poisoning: new prospects for therapy].

The filter has been approved by the Food and Drug Administration for the removal of beta-2 microglobulin in patient undergoing hemodialysis. We used the filter (the patient agrees) off label, in the course of digitalis intoxication and we have shown that the filter is capable of removing the drug effectively.

The lipid dependence of antimicrobial peptide activity is an unreliable experimental test for different pore models.

Antimicrobial peptides usually kill bacteria by making their membranes permeable. Two main models (barrel-stave and Shai-Matsuzaki-Huang) have been proposed to describe the peptide-induced pores. Although several experimental tests can be exploited to discriminate between these two models, the dependence of peptide activity on lipid properties (intrinsic curvature and membrane thickness) is routinely used for this purpose. Here, we show that, contrary to what is currently accepted, this criterion is unreliable.