Stimulation Crosstalk Between Cochlear And Vestibular Spaces During Cochlear Electrical Stimulation

OBJECTIVES

Possible beneficial "crosstalk" during cochlear implant stimulation on otolith end organs has been hypothesized. The aim of this case-control study is to analyze the effect of electrical cochlear stimulation on the vestibule (otolith end-organ), when using a cochleo-vestibular implant, comparing vestibular stimulation (VI) and cochlear stimulation (CI).

METHODS

Four patients with bilateral vestibulopathy were included. A double electrode array research implant was implanted in all cases. Dynamic Gait Index (DGI), VOR gain measured by using vestibular head impulse test (vHIT), acoustic cervical myogenic responses (cVEMP) recordings, and electrical cVEMP were used in all cases. Trans-impedance Matrix (TIM) analysis was used to evaluate the current flow from the cochlea to the vestibule.

RESULTS

While patients did not have any clinical vestibular improvement with the CI stimulation alone, gait metrics of the patients revealed improvement when the vestibular electrode was stimulated. The average improvement in the DGI was 38% when the vestibular implant was activated, returning to the normal range in all cases. Our findings suggest that any current flow from the cochlear space to the otolith organs was insufficient for effective cross-stimulation. The functional results correlated with the data obtained in TIM analysis, confirming that there is no current flow from the cochlea to the vestibule.

CONCLUSION

The only way to produce effective electrical otolith end-organ stimulation, demonstrated with this research implant, is by direct electrical stimulation of the otolith end organs. No effective cross-stimulation was found from cochlear electrode stimulation.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:2349-2355, 2024.

Basic Science in Movement Disorders: Fueling the Engine of Translation into Clinical Practice

Basic Science is crucial for the advancement of clinical care for Movement Disorders. Here, we provide brief updates on how basic science is important for understanding disease mechanisms, disease prevention, disease diagnosis, development of novel therapies and to establish the basis for personalized medicine. We conclude the viewpoint by a call to action to further improve interactions between clinician and basic scientists. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Approaches to nonlinear curve fitting in laboratory medicine

Nonlinear curve fitting is an important process in laboratory medicine, particularly with the increased use of highly sensitive antibody-based assays. Although the process is often automated in commercially available software, it is important that clinical scientists and physicians recognize the limitations of the various approaches used and are able to select the most appropriate model. This article summarizes the key nonlinear functions and demonstrates their application to common laboratory data. Following this, a basic overview of the statistical comparison of models is presented and then a discussion of important algorithms used in nonlinear curve fitting. An accompanying Microsoft Excel workbook is available that can be used to explore the content of this article.

Changes in Cross-sectional Area of the Median Nerve and Boston Carpal Tunnel Questionnaire Scores After Carpal Tunnel Release

BACKGROUND

We hypothesized that postoperative Boston Carpal Tunnel Questionnaire (BCTQ) scores and ultrasound (US) measurements of the median nerve cross-sectional area (CSA) at the distal wrist crease are significantly decreased at 2-week, 6-week, and ≥ 6 months follow-up appointments, compared with baseline values.

METHODS

This study was a retrospective chart review of patients who presented to a single hand clinic with evidence of carpal tunnel syndrome over a 6-year period (2014-2020). Patients received baseline US measurements of the median nerve CSA as well as completion of the BCTQ, and for the patients who underwent carpal tunnel release (CTR), postoperative US measurements and questionnaire scores were obtained at 2 weeks, 6 weeks, or ≥ 6 months postoperatively.

RESULTS

This study included 224 separate wrists. Median Nerve CSA measurements were 13.2 ± 4.5 mm2 at baseline, 11.9 ± 3.6 mm2 at 2 weeks postoperatively, 11.6 ± 4.5 mm2 at 6 weeks postoperatively, and 11.7 ± 4.3 mm2 at 6 months or more (P = .002). The BCTQ Symptom Severity Scale scores were 3.14 ± 0.76 at baseline, 1.76 ± 0.63 at 2 weeks, 1.68 ± 0.70 at 6 weeks, and 1.41 ± 0.64 at 6 months or longer (P < .001). The BCTQ Functional Status Scale scores were 2.56 ± 0.89 at baseline, 2.03 ± .1.0 at 2 weeks, 1.65 ± 0.77 at 6 weeks, and 1.36 ± 0.61 at 6 months or longer (P < .001).

CONCLUSIONS

These findings demonstrated a sustained decrease in median nerve CSA and patient-reported outcomes following CTR at 2 weeks, 6 weeks, and between 6 and 12 months.

Conduit/Wrap Repairs to Digital Nerves Provide Residual Strength After Peak Loading

BACKGROUND

Many techniques are used for digital nerve repair, most commonly coaptation by sutures. Nerve repairs must be strong while offering an environment for nerve regeneration. Sutures can damage the nerve and thereby limit growth and regeneration. Sutures can rip and cause sudden catastrophic failure. Fibrin glue and conduit-wraps allow a good environment for growth, but neither provides much strength. A benefit to conduit repair would arise if the repair maintained integrity after the peak load so that the path for regrowth stayed in place. The goal for this study was to determine whether conduit with glue provides continued strength after a maximum load is reached.

METHODS

Digital cadaveric nerves were harvested and repaired with 2 epineurial sutures, conduit, and fibrin glue in all combinations. Tests to failure were performed, gap displacement between nerve ends recorded, and the postpeak load energy to dissociation of the nerve and conduit was calculated.

RESULTS

Conduit with glue and 2 sutures at the end had the greatest energy and displacement after the peak load but was not significantly different than conduit with glue and 1 suture. Conduit with glue alone obtained statistically the same displacement as conduit with glue and 2 sutures. Conduit, with or without glue, and 2 sutures was statistically the same as suture only repair for peak load.

CONCLUSION

Conduit/wrap maintains a load capacity and a path for nerve regeneration after the peak. Suture at the ends of conduit, not at the coaptation site, reduces damage at the point of injury.

Distal femur fractures: basic science and international perspectives

Distal femur fractures are challenging injuries to manage, and complication rates remain high. This article summarizes the international and basic science perspectives regarding distal femoral fractures that were presented at the 2022 Orthopaedic Trauma Association Annual Meeting. We review a number of critical concepts that can be considered to optimize the treatment of these difficult fractures. These include biomechanical considerations for distal femur fixation constructs, emerging treatments to prevent post-traumatic arthritis, both systemic and local biologic treatments to optimize nonunion management, the relative advantages and disadvantages of plate versus nail versus dual-implant constructs, and finally important factors which determine outcomes. A robust understanding of these principles can significantly improve success rates and minimize complications in the treatment of these challenging injuries.

Preclinical models of orthopaedic trauma: Orthopaedic Research Society (ORS) and Orthopaedic Trauma Association (OTA) symposium 2022

Orthopaedic trauma remains a leading cause of patient morbidity, mortality, and global health care burden. Although significant advances have been made in the diagnosis, treatment, and rehabilitation of these injuries, complications such as malunion, nonunion, infection, disuse muscle atrophy and osteopenia, and incomplete return to baseline function still occur. The significant inherent clinical variability in fracture care such as differing patient demographics, injury patterns, and treatment protocols make standardized and replicable study, especially of cellular and molecular based mechanisms, nearly impossible. Hence, the scientists dedicated to improving therapy and treatments for patients with orthopaedic trauma rely on preclinical models. Preclinical models have proven to be invaluable in understanding the timing between implant insertion and bacterial inoculation on the bioburden of infection. Posttraumatic arthritis (PTOA) can take years to develop clinically, but with a porcine pilon fracture model, posttraumatic arthritis can be reliably induced, so different surgical and therapeutic strategies can be tested in prevention. Conversely, the racehorse presents a well-accepted model of naturally occurring PTOA. With preclinical polytrauma models focusing on chest injury, abdominal injury, multiple fractures, and/or head injury, one can study how various injury patterns affect fracture healing can be systemically studied. Finally, these preclinical models serve as a translational bridge to for clinical application in human patients. With selection of the right preclinical model, studies can build a platform to decrease the risk of emerging technologies and provide foundational support for therapeutic clinical trials. In summary, orthopaedic trauma preclinical models allow scientists to simplify a complex clinical challenge, to understand the basic pathways starting with lower vertebrate models. Then, R&D efforts progress to higher vertebrate models to build in more complexity for translation of findings to the clinical practice.

Social Media Posts About Carpal Tunnel Release: A Cross-Sectional Analysis of Patient and Surgeon Perspectives

BACKGROUND

Social media provides an increasingly popular, unfiltered source of perspectives on healthcare. The objective of this study is to characterize the landscape of social media posts regarding carpal tunnel release (CTR).

METHODS

Content was queried from Instagram between February 2, 2019 to August 12, 2021 using the hashtags #carpaltunnelrelease and #carpaltunnelsurgery. The 1500 most-liked posts were analyzed. Poster demographics including age, gender, region, and symptom qualities and post characteristics including type, number, timing relative to surgery, tone, and satisfaction were collected. Categorical variables were compared utilizing chi-squared test. Univariate and multivariate regression were performed.

RESULTS

The most popular post types included single photo (55.2%), multiple photos (18.8%), or single video (18.2%). Of all, 70.6% posts had fewer than 50 "likes." Patients accounted for 51.8% of posts, followed by surgeons (13.3%), other health care providers (11.7%), and physical therapists (8.8%). Women (66.7%) outnumbered men (33.3%). Fifty-five percent of posts were domestic. Posts mostly depicted postoperative care (85.6%). The most frequently mentioned symptoms were pain, burning, numbness, and tingling. Of all posts, 45.1% had a positive tone, 49.1% neutral, and 5.7% negative. Univariate analysis revealed that posters who were patients, underwent open CTR, and were female were more likely to post negative sentiments.

CONCLUSIONS

Most posts regarding CTR are from patients, are postoperative, and are positive or neutral. Although rare, negative posts were more likely to originate from posters who are patients, female, or underwent open CTR. With this information, surgeons will be better prepared to address patient concerns, set patient expectations, and enter the social media themselves.

Medical Students' Perception of Pathology in Saudi Arabia

Pathology is the bridge between basic science and clinical practice. An inadequate perception of pathology leads to an incomplete understanding of diseases, which consequently affects its management. This study aims to identify medical students' perceptions of pathology in medical colleges around Saudi Arabia and use their feedback to improve teaching strategies. A validated online self-structured questionnaire form was distributed to medical students in basic and clinical years, including private and governmental universities in all regions of Saudi Arabia. The study comprised a total of 476 medical students. It revealed that n = 226 (48%) of the participants were not aware of pathologists' roles, and n = 262 (55%) of students reported that the main reason was insufficient exposure to actual pathology practice. A total of n = 209 (44%) students believed the current teaching methods in the basic years were insufficient to provide clear perceptions of pathology. The majority of participants n = 366 (77%) chose practical sessions as the most effective strategy in teaching pathology. Our study demonstrated that medical students require more engagement in laboratories to improve their perception. We suggest that Saudi medical schools need to deliver more comprehensive and practical teaching methods that reflect the actual practice of pathology.

Pepsin Inhibitors Prevent Inflammation and Loss of Laryngeal Barrier Function in Mice with Gastroesophageal Reflux

OBJECTIVE

This study aimed to evaluate the role of pepsin inhibitors in the inflammatory response and their effects on laryngeal mucosal integrity during gastroesophageal reflux (GERD) under in vivo conditions.

METHODS

A surgical model of GERD was used, in which mice were treated with pepstatin (0.3 mg/kg) or darunavir (8.6 mg/kg) for 3 days. On the third day after the experimental protocol, the laryngeal samples were collected to assess the severity of inflammation (wet weight and myeloperoxidase activity) and mucosal integrity (transepithelial electrical resistance and paracellular epithelial permeability to fluorescein).

RESULTS

The surgical GERD model was reproduced. It showed features of inflammation and loss of barrier function in the laryngeal mucosa. Pepstatin and darunavir administration suppressed laryngeal inflammation and preserved laryngeal mucosal integrity.

CONCLUSION

Pepsin inhibition by the administration of pepstatin and darunavir improved inflammation and protected the laryngeal mucosa in a mouse experimental model of GERD.

LEVEL OF EVIDENCE

NA Laryngoscope, 2024.

Three-dimensional changes in the cranial base associated with soft-diet feeding

BACKGROUND

Masticatory activity affects the morphology of the maxillo-mandibular complex, however, its influence on the cranial base remains to be elucidated. The recent integration of quantitative morphometric analysis with 3D imaging enabled a comprehensive and high-resolution morphological characterization of the craniofacial complex. We aimed to investigate the influence of masticatory activity on the morphology of the growing cranial base by three-dimensional (3D) geometric morphometric approach using micro-CT.

METHODS

The micro-CT data was reanalyzed to illustrate the 3D shape of the cranial base, and wireframe models were generated by connecting landmarks on the images. In the original study, mice were fed a soft diet (SD) of powdered pellets or a conventional hard diet (HD) for 6 weeks from 3 to 9 weeks of age, immediately after weaning. A principal component (PC) analysis analyzed shape variations and assessed their significance, while canonical variate (CV) analysis facilitated the comparison and differentiation of groups based on shape, unveiling meaningful shape distinctions.

RESULTS

Three PCs were extracted that significantly separated the SD and HD groups among those explaining variations in shape. These PCs were related to the length of the sphenoid bone, the width of the anterior part of the sphenoid bone, and the length of the cranial base. Furthermore, one CV effectively distinguished SD from HD, and CV analysis showed that the sphenoid was shortened in the length and narrowed at the border of the temporal bone in SD mice.

CONCLUSIONS

Masticatory loading affects the skeletal development of the cranial base. The morphology of the sphenoid bone was affected in both the sagittal and transverse axes.

Forearm Lipoma Causing PIN Compression: Literature Review and Meta-Analysis of Predictors for Motor Recovery

BACKGROUND

Lipomas are a rare cause of posterior interosseous nerve (PIN) compression. A systematic review of predictors for motor recovery has not been performed. This study sought to evaluate whether patient or lipoma characteristics are associated with motor recovery and could be used to determine when immediate tendon transfers at the time of excision should be performed.

METHODS

Articles describing patients with forearm lipomas resulting in PIN compression with motor weakness were included. Patient age, gender, symptom duration, laterality and largest dimension of lipoma, surgical intervention, and motor recovery were identified. Article quality was assessed via the Methodological Index for Non-Randomized Studies criteria.

RESULTS

Thirty articles reporting on 34 patients were identified. Average age was 58.2 years. Average largest lipoma dimension was 5.7 cm. All patients underwent lipoma removal, and 2 had concomitant tendon transfers. In all, 73.5% of patients had complete motor recovery at an average of 9.7 months. Patient age and largest dimension of lipoma, and duration of symptoms were not significant predictors of motor recovery. Symptom duration was a significant predictor of motor recovery in binary regression, particularly if < 18 months.

CONCLUSIONS

The majority of patients with PIN weakness secondary to lipoma are likely to have complete motor recovery after excision alone. Concomitant tendon transfers should be considered for patients symptomatic for greater than 18 months. Further, adequately powered, studies are required to stratify risk factors and evaluate other modalities to identify the minority of patients who would benefit from immediate tendon transfer.

Suppressing Effects of Docosahexaenoic Acid-Containing Diets on Oxidative Stress and Fibrosis in 5/6 Nephrectomized Rats

Key Points

Increased albuminuria on 5/6 nephrectomized rats, as reported earlier, is attenuated by arachidonic acid–containing and docosahexaenoic acid (DHA)–containing diets. This study established that DHA affects both oxidative stress and fibrosis in the kidney. DHA suppressed the oxidative stress and fibrosis, hence suppressing the progression of renal failure.

Background

Urinary albumin excretion gradually increases after nephrectomy, which eventually progresses toward renal failure. Our previous study had reported that arachidonic acid (ARA)–containing or docosahexaenoic acid (DHA)–containing diet attenuates the increasing urinary albumin excretion. This study aimed to investigate the effects of ARA-containing or/and DHA-containing diets on oxidative stress and fibrosis that cause kidney injury in 5/6 nephrectomized rats.

Methods

Sprague–Dawley rats were randomly divided into control group, ARA group, DHA group, and ARA+DHA group. Rats underwent 5/6 kidney removal and were fed ARA-containing or/and DHA-containing diet each five groups continuously for 4 weeks. We collected urine, plasma, and kidney samples 4 weeks after surgery and investigated the effects of ARA-containing and DHA-containing diets on oxidative stress, inflammation, and fibrosis in the kidney.

Results

Urinary albumin excretion, indoxyl sulfate, reactive oxygen species, TNF-α levels, and fibrosis in the kidney were all increased on nephrectomy; however, they were attenuated after feeding the rats with DHA-containing diet.

Conclusion

One possible mechanism of preventing chronic renal failure would be the suppression of indoxyl sulfate accumulation, oxidative stress, and kidney fibrosis arising due to nephrectomy. The results collectively suggested that DHA-containing diets can suppress the progression of renal failure.

The importance of appraising articles and conducting psychiatric journal clubs

OBJECTIVE

To describe the importance of scientifically rigorous journal clubs in psychiatric education, and to provide a framework to effectively run journal clubs and appraise articles in a journal club format. This paper explores the concept of journal clubs and describes issues with the current state of academic science. It then lists factors associated with effectiveness of journal clubs and outlines a structure for appraising articles relevant to psychiatric practice in a journal club format.

CONCLUSIONS

Current models of academic research and publishing, which can reward practices vulnerable to multiple forms of bias, make the consistent and valued use of journal clubs in psychiatric education and continuing professional development more important than ever. The literature shows that journal clubs can provide a valuable forum for mental health clinicians to update themselves on recent medical and scientific knowledge, while practicing and teaching skills in critical appraisal of research, statistics, clinical decision-making and epidemiology.

Diagnostic Performance of 10 Mathematical Formulae for Identifying Blood Donors with Thalassemia Trait

OBJECTIVE

To compare the diagnostic performance of 10 mathematical formulae for identifying thalassemia trait in blood donors.

METHODS

Compete blood counts were conducted on peripheral blood specimens using the UniCel DxH 800 hematology analyzer. Receiver operating characteristic curves were used to evaluate the diagnostic performance of each mathematical formula.

RESULTS

In the 66 donors with thalassemia and 288 subjects with no thalassemia analyzed, donors with thalassemia trait had lower values for mean corpuscular volume and mean corpuscular hemoglobin than subjects without thalassemia donors (77 fL vs 86 fL [P < .001]; 25 pg vs 28 pg [P < .001]). The formula developed by Shine and Lal in 1977 showed the highest area under the curve value, namely, 0.9. At the cutoff value of <1812, this formula had maximum specificity of 82.35% and sensitivity of 89.58%.

CONCLUSIONS

Our data indicate that the Shine and Lal formula has remarkable diagnostic performance in identifying donors with underlying thalassemia trait.

Accuracy and Safety of Non-Image Guided Trigger Finger Injections: A Cadaveric Study

BACKGROUND

Stenosing flexor tenosynovitis is commonly treated by injection of corticosteroids into the flexor tendon sheath. However, there is no consensus in the literature regarding the optimal technique, specifically when not utilizing ultrasound guidance. Here, we present a cadaver study in which 3 common techniques of flexor sheath injection were compared with regard to their accuracy and safety profiles.

METHODS

Fifteen fresh-frozen cadaver hands (60 digits) were evenly divided into 3 groups (20 digits per group). Digits in each group were injected with methylene blue dye using 1 of the 3 techniques (palmar-to-bone, palmar supra-tendinous, and mid-axial). The fingers were then dissected and were inspected for location of dye, as well as injury to tendon or digital nerves.

RESULTS

The mid-axial technique demonstrated the greatest accuracy with the highest rate of all intra-sheath injection, 15 of 20 digits (75%), while the palmar-to-bone technique produced the most combined intra- and extra-sheath injections, 13 of 20 digits, (65%) and the palmar supra-tendinous technique resulted in the most all extra-sheath injections, 9 of 20 digits (45%). The difference in rates of all intra-sheath injection was significant (P = .01). The mid-axial technique also produced the fewest intra-tendinous injections 0 of 20, although this result did not reach statistical significance (P = .15).

CONCLUSIONS

Compared to other common non-image guided flexor tendon sheath injection techniques, the mid-axial injection technique was found to be the most accurate in producing all intra-sheath injection and least likely to result in intra-tendinous injection.

Contrast Enhanced Computed Tomography in the Diagnosis of Acute Pyogenic Flexor Tenosynovitis

BACKGROUND

The diagnosis of infectious flexor tenosynovitis (FTS) has historically been made based on physical exam using Kanavel's signs. The specificity of these findings has come into question. We looked to evaluate the use of contrast-enhanced computed tomography (CT) in increasing the successful diagnosis of FTS.

METHODS

Two adult cohorts were formed, one of patients with FTS confirmed in the operating room and the second of patients with ICD.10 identified finger cellulitis (FC), without concomitant FTS. Demographics, laboratory values, CT scans, and examination findings were evaluated. Axial CTs were evaluated in the coronal and sagittal planes and tendon sheath/tendon width were measured. The tendon sheath/tendon was recorded as a ratio in the coronal (CR) and sagittal (SR) planes. Continuous and dichotomous variables were analyzed and measures of sensitivity, specificity, and predictivity were calculated. Seventy patients were included, 35 in the FTS cohort and 35 with FC.

RESULT

A higher number of Kanavel signs were present in the FTS group (2.9 vs. 0.5, P < .05), with CR and SR both being significantly larger in the FTS group (P < .05). CR and SR cutoffs ≥ 1.3 provided high sensitivity, specificity, and positive predictive value (PPV) for FTS. Likelihood of FTS increased 5.9% and 5.5% for every 0.1 increase in CR and SR, respectively, with a 14% increase for every additional Kanavel sign.

CONCLUSION

In conclusion, CT ratios are useful in identifying FTS; and when used on their own or in combination with Kanavel's signs, CR and SR objectively improve the diagnosis of FTS.

Radial Sided Triangular Fibrocartilage Complex Tears: A Comprehensive Review

When evaluating the available literature on the diagnosis and management of triangular fibrocartilage complex tears (TFCC), ulnar tears comprise the major focus of TFCC literature. Radial-sided (Class 1D) tears are seldom researched or discussed. The purpose of this study was to review the methods for identifying and treating radial-sided TFCC lesions, by examining the anatomy of the TFCC, the pathology of its radial portion, diagnostic techniques, and both surgical and nonoperative treatments. The avascular nature of the radial TFCC may influence its healing potential. Magnetic resonance arthrogram is the gold standard for non-invasively diagnosing a radial-sided tear. Non-operative management should be exhausted prior to surgical intervention, which commonly involves an inside-out repair involving radial trans-osseous sutures. Still, the literature is limited by patient sample size and therefore requires a greater population of class 1-D tears to confirm optimal diagnostic and treatment methods.

Extensor Tendon Integrity After Percutaneous Placement of Intramedullary Metacarpal Screws: A Cadaveric Study

BACKGROUND

Intramedullary implants are an increasingly common method for fixation of metacarpal fractures. Numerous techniques for instrumentation have been described with varied consideration for the risk of extensor tendon injury. The current cadaveric study evaluates the prevalence and degree of extensor tendon injury and compares percutaneous approaches with different drilling techniques.

METHODS

Ninety-six metacarpals (thumbs excluded) from 24 fresh-frozen cadaveric upper extremities were used to compare 2 percutaneous approaches and 2 drilling techniques. This resulted in 4 subgroups available for comparison: oscillate to bone (OB), forward to bone (FB), oscillating through the skin (OS), and forward through the skin (FS). After instrumentation, the extensor tendons were dissected and disruption was characterized. The main outcome measures were tendon "hit rate" and relative extensor tendon defect width.

RESULTS

Tendon hit rate was significantly higher in the long finger (LF), that is, 79.2%, compared with other metacarpals: index finger, 20.8%; ring finger, 12.5%; and small finger 25%. The mean relative tendon disruption was significantly less in the OB group (16.05%) compared with the other groups: FB (31.84%), FS (31.50%), and OS (29.85%).

CONCLUSION

Retrograde intramedullary screw fixation of metacarpal fractures can be performed using percutaneous approaches without a significant disruption of the extensor mechanism. Instrumentation through a longitudinal stab incision down to the metacarpal head and the use of drill oscillation minimize injury to the extensor tendons. The LF extensor tendon is most at risk with retrograde intramedullary implant placement.

Professional Identity Formation of Basic Science Medical Educators: A Qualitative Study of Identity Supports and Threats

PURPOSE

Basic science medical educators (BSME) play a vital role in the training of medical students, yet little is known about the factors that shape their professional identities. This multi-institutional qualitative study investigated factors that support and threaten the professional identity formation (PIF) of these medical educators.

METHOD

A qualitative descriptive study was conducted with a purposive sample of 58 BSME from 7 allopathic medical schools in the U.S. In-depth semi-structured interviews of individual BSME were conducted between December 2020 and February 2021 to explore the facilitators and barriers shaping the PIF of BSME. Thematic analysis was conducted.

RESULTS

Factors shaping PIF were grouped into 3 broad domains: personal, social, and structural. Interrelated themes described a combination of factors that pushed BSME into teaching (early or positive teaching experiences) and kept them there (satisfaction and rewards of teaching, communities of like-minded people), as well as factors that challenged their PIF (misunderstanding from medical students, clinical, and research faculty, lack of formal training programs, and lack of tenure-track educator positions). The structural environment was reported to be crucial for PIF and determined whether BSME felt that they belonged and were valued.

CONCLUSIONS

This study shows that although most BSME derive a sense of fulfillment and meaning from their role as medical educators, they face considerable obstacles during their PIF. Structural change and support are needed to increase recognition, value, promotion, and belonging for BSME to improve the satisfaction and retention of this important group of faculty.

Good sleep is a mood buffer for young women during menses

STUDY OBJECTIVES

We sought to elucidate the interaction between sleep and mood considering menstrual cycle phase (menses and non-menses portions of the cycle) in 72 healthy young women (18-33 years) with natural, regular menstrual cycles and without menstrual-associated disorders. This work fills a gap in literature of examining mood in context of sleep and menstrual cycle jointly, rather than individually.

METHODS

Daily subjective measures of sleep and mood, and date of menses were remotely, digitally collected over a 2-month period. Each morning, participants rated their sleep on the previous night, and each evening participants rated the extent of positive and negative mood for that day. Objective sleep was tracked with a wearable (ŌURA ring) during month 2 of the study. Time-lag cross-correlation and mixed linear models were used to analyze the significance and directionality of the sleep-mood relationship, and how the interaction between menstrual cycle status and sleep impacted mood levels.

RESULTS

We found that menstrual status alone did not impact mood. However, subjective sleep quality and menstrual status interacted to impact positive mood (p < .05). After a night of perceived poor sleep quality, participants reported lower positive mood during menses compared to non-menses portions of the cycle, while after a night of perceived good sleep quality participants reported equivalent levels of positive mood across the cycle.

CONCLUSIONS

We suggest that the perception of good sleep quality acts as a mood equalizer, with good sleep providing a protective buffer to positive mood across the menstrual cycle.

Effects of Premixing Betamethasone and Lidocaine on Chondrocyte Inflammation in an In Vitro Model

BACKGROUND

It is common practice for hand surgeons to premix corticosteroids with a local anesthetic and store the mixture in pre-loaded syringes for rapid use during clinic. However, any possible loss of efficacy with this practice has never been studied. The purpose of this study, therefore, is to determine whether premixing betamethasone sodium phosphate/betamethasone acetate (BSP) and lidocaine (L) at different time intervals from injection has diminishing anti-inflammatory effects on chondrocytes in vitro.

METHODS

Human articular chondrocytes were partitioned into six groups: two controls and four experimental conditions. The negative control had growth media only. The positive control had growth media and inflammatory cytokines (interleukin-1β and oncostatin M). Experimental conditions were additionally treated with BSP alone or BSP mixed with lidocaine (BSP + L) at the time of treatment (0 hours), or at 4 or 24 hours prior. Relative expressions of inflammatory genes were measured.

RESULTS

Relative to the positive control, chondrocytes in all experimental conditions decreased expression of TNF-α, MMP-3, and ADAMTS-4. Chondrocytes exposed to BSP only or BSP + L at 4 hours or 24 hours prior to treatment decreased expression of IL-8. Chondrocytes exposed to BSP only or BSP + L at 0 hours or 4 hours prior to treatment decreased expression of MMP-1. There were no significant differences in expression of IL-6 or MMP-13.

CONCLUSIONS

Treatment with BSP + L prepared in pre-loaded syringes at varying time intervals up to 24 hours prior to injection does not significantly impact the ability of the mixture to reduce expression of certain key inflammatory mediators in vitro.

In vitro Nasodine Can be an Effective Antibiofilm Agent for Biofilms that May Cause CRS

OBJECTIVES

Bacterial biofilms on the sinonasal mucosa, especially biofilms of Staphylococcus aureus, are associated with greater severity and recalcitrance of chronic rhinosinusitis (CRS). There are few, if any, antibiofilm agents suitable for sinonasal application available for the management of this problem. Nasodine® Nasal Spray (Nasodine) is a 0.5% povidone-iodine-based formulation that has been developed for sinonasal application. We investigated the antibiofilm efficacy of Nasodine to determine whether it may be a candidate for the treatment of biofilm-associated CRS.

METHODS

Biofilms of S. aureus ATCC 6538 were grown in vitro using the Centers for Disease Control biofilm reactor. Intact biofilms were treated by immersion in 0.9% saline (control), half concentration Nasodine, or full concentration Nasodine for between 5 min and 6 h. Further biofilm cells were dispersed into suspension then treated for between 30 s and 5 min. Surviving bacteria were then enumerated by culture and counting colonies, and the log10 reduction in viable bacteria was compared with control.

RESULTS

Nasodine demonstrated time and concentration-dependent bacterial killing against intact biofilm. Statistically significant reductions in viable bacteria from intact biofilms were seen with exposures as brief as 5 min. Nasodine consistently eradicated dispersed biofilm within 1 min.

CONCLUSION

Nasodine is highly active against biofilms of S. aureus ATCC 6538 in vitro. Biofilm killing is impeded by the presence of the intact biofilm structure.

LAY SUMMARY

In chronic rhinosinusitis (CRS), bacterial communities called biofilms are associated with more severe inflammation. An iodine-based nasal spray called Nasodine almost completely eradicates bacterial biofilms after 6 h of exposure. Nasodine may be useful for treating CRS. Laryngoscope, 133:2490-2495, 2023.

Insights into the Regulation of GFR by the Keap1-Nrf2 Pathway

Key Points

Kelch-like erythroid cell-derived protein with CNC homology (ECH)-associated protein 1-NF (erythroid-derived 2)–like 2 pathway increases GFR without an appreciable increase in intraglomerular pressure. Kelch-like ECH-associated protein 1-NF (erythroid-derived 2)–like 2 pathway regulates GFR through changes in filtration area by modulating calcium dynamics and contractility in glomerular cells.

Background

Literature data suggest that the activation of the Kelch-like ECH-associated protein 1 (Keap1)-NF (erythroid-derived 2)–like 2 (Nrf2) pathway increases GFR in patients with type 2 diabetes and CKD. However, the mechanisms whereby the Keap1-Nrf2 pathway regulates GFR are unknown.

Methods

Various renal physiological parameters were assessed in C57BL/6 mice (wild-type), Nrf2 -deficient mice, and Nrf2 -activated Keap1- knockdown mice. In addition, these parameters were assessed after the administration of receptor targeting agent (RTA) dh404 (CDDO‐dhTFEA), an Nrf2 activator.

Results

Pharmacologic and genetic Keap1 -Nrf2 activation increased renal blood flow (P < 0.05), glomerular volume (P < 0.05), and GFR (P < 0.05) but did not alter the afferent-to-efferent arteriolar diameter ratio or glomerular permeability. Calcium influx into the podocytes through transient receptor potential canonical (TRPC) channels in response to H2O2 was suppressed by Keap1-Nrf2 activation and TRPCs inhibition. Treatment with a TRPC6 and TRPC5 inhibitors increased single-nephron GFR in wild-type mice.

Conclusions

In conclusion, the Keap1-Nrf2 pathway regulates GFR through changes in ultrafiltration by modulating redox-sensitive intracellular calcium signaling and cellular contractility, mediated through TRPC activity, in glomerular cells, particularly the podocytes.

Overview of The the Clinician Investigator Trainees' Research Presented at The 2022 CSCI-CITAC Joint Meeting

The 2022 Annual Joint Meeting (AJM) and Young Investigators' Forum of the Canadian Society for Clinical Investigation / Société Canadienne de recherches clinique (CSCI/SCRC) and Clinician Investigator Trainee Association of Canada/Association des cliniciens-chercheurs en formation du Canada (CITAC/ACCFC) was held in Montréal, November 13-14, 2022. The theme of this year's AJM was "Strength in Perseverance" and focused on highlighting clinician-investigator trainee achievements and resilience in research engagement through recent challenging and unprecedented times. The opening remarks were given by Nicola Jones (president of CSCI/SCRC) and Heather Whittaker (past president of CITAC/ACCFC). The keynote speaker was Dr. Michael Strong, who delivered the presentation "The Future of Clinician Scientists in Canada." Dr. Caroline Quach (Université de Montréal) received the CSCI Distinguished Scientist Award and Dr. Amy Metcalfe (University of Calgary) received the CSCI Joe Doupe Young Investigator Award. Each of the clinician-scientists delivered presentations on their award-winning research. The four interactive workshops included "Social Media in Science and Medicine," "Diversity in Science and Medicine," "Running a Successful Research Program," and "Mentorship in Action." The AJM also included presentations from clinician investigator trainees from across the country. Over 90 abstracts were showcased at this year's meeting, most of which are summarized in this review. Six outstanding abstracts were selected for oral presentations during the President's Forum.

Where Does Ultrasound Fit in the Diagnostic Algorithm for Cubital Tunnel Syndrome?

BACKGROUND

Ultrasound (US) has emerged as a promising supplement to electrodiagnostic studies (EDX) in the diagnosis of cubital tunnel syndrome (CuTS) and has potential to be performed by novice operators. Our objective is to understand the discrepancies in assessment between the two modalities and to assess the utility of US in CuTS diagnosis by a novice operator.

METHODS

Patients who presented to a single tertiary academic medical center and clinically diagnosed with CuTS were prospectively enrolled. Electrodiagnostic studies were performed along with US measurements of the cross-sectional area (CSA) of the ulnar nerve by both a board-certified physiatrist and novice operator. Electrodiagnostic study and US outcomes were compared among four diagnostic impression groups: EDX-/US-, EDX+/US-, EDX-/US+, and EDX+/US+.

RESULTS

Sixteen patients were classified as abnormal by both EDX and US, 14 were classified abnormal by US only, 3 were classified abnormal by EDX only, and 6 were classified normal by both EDX and US (P = .008, K = 0.14). The EDX+/US+ group had a significantly reduced sensory amplitude compared with the EDX-/US+ (P = .04) group. Diagnostic classifications between a board-certified physiatrist and novice operator were in moderate agreement (K = 0.58, P = .08).

CONCLUSIONS

Ultrasound detected a greater proportion of patients as abnormal than EDX. A subset of patients with clinical diagnoses of CuTS had normal sensory amplitudes but increased maximum nerve CSAs. Competency in US may be easily acquired with minimal training, suggesting its potential to be extended for use by other members of the health care team.

Accuracy of MRI in Assessment of High-Grade Partial Distal Biceps Tears

BACKGROUND

Magnetic resonance imaging (MRI) is commonly used to diagnose and assess the extent of partial distal biceps injuries. The aim of this study was to report on the accuracy of MRI and the effect of injury history and study timing on its performance.

METHODS

A retrospective review of all patients who underwent surgical treatment of partial thickness distal biceps tears at a single center by multiple surgeons was performed. Inclusion criteria consisted of the performance of a preoperative MRI and documentation of the intraoperatively visualized extent of the tear, and 68 patients met the criteria for inclusion. A chart review was completed to evaluate the symptom duration, injury history, and tear extent.

RESULTS

All patients had distal biceps tears of greater than 50% intraoperatively. However, MRI did not indicate any tearing in 20 (29%) patients, and its sensitivity for high-grade tear was 44%. Magnetic resonance imaging was significantly less likely to be read as high-grade tears in patients with insidious onset of their symptoms in comparison with patients who reported a traumatic onset (27% vs 55%, P = .024). However, the time from symptom onset to MRI did not significantly correlate with diagnosis of a high-grade tear on MRI (r = -0.15, P = .21).

CONCLUSIONS

These results indicate that MRI can underreport partial distal biceps tear extent, and this more commonly occurs in patients with insidious onset of pain.

Computational fluid dynamics simulate optimal design of segmental arteries reattachment: Influence of blood flow stagnation

Objectives

This study aimed to simulate blood flow stagnation using computational fluid dynamics and to clarify the optimal design of segmental artery reattachment for thoracoabdominal aortic repair.

Methods

Blood flow stagnation, defined by low-velocity volume or area of the segmental artery, was simulated by a 3-dimensional model emulating the systolic phase. Four groups were evaluated: direct anastomosis, graft interposition, loop-graft, and end graft. Based on contemporary clinical studies, direct anastomosis can provide a superior patency rate than other reattachment methods. We hypothesized that stagnation of the blood flow is negatively associated with patency rates. Over time, velocity changes were evaluated.

Results

The direct anastomosis method led to the least blood flow stagnation, whilst the end-graft reattachment method resulted in worse blood flow stagnation. The loop-graft method was comparatively during late systole, which was also influenced by configuration of the side branch. Graft interposition using 20 mm showed a low-velocity area in the distal part of the side graft. When comparing length and diameter of an interposed graft, shorter and smaller branches resulted in less blood flow stagnation.

Conclusions

In our simulation, direct anastomosis of the segmental artery resulted in the most efficient design in terms of blood flow stagnation. A shorter (<20 mm) and smaller (<10 mm) branch should be used for graft interposition. Loop-graft is an attractive alternative to direct anastomosis; however, its blood flow pattern can be influenced.

Kir1.1 and SUR1 are not implicated as subunits of an adenosine triphosphate-sensitive potassium channel involved in diazoxide cardioprotection

Objective

The adenosine triphosphate-sensitive potassium channel opener diazoxide mimics ischemic preconditioning and is cardioprotective. Clarification of diazoxide's site and mechanism of action could lead to targeted pharmacologic therapies for patients undergoing cardiac surgery. Several mitochondrial candidate proteins have been investigated as potential adenosine triphosphate-sensitive potassium channel components. Renal outer medullary potassium (Kir1.1) and sulfonylurea sensitive regulatory subunit 1 have been suggested as subunits of a mitochondrial adenosine triphosphate-sensitive potassium channel. We hypothesized that pharmacologic blockade or genetic deletion (knockout) of renal outer medullary potassium and sensitive regulatory subunit 1 would result in loss of diazoxide cardioprotection in models of global ischemia with cardioplegia.

Methods

Myocyte volume and contractility were compared after Tyrode's physiologic solution (20 minutes), stress (hyperkalemic cardioplegia ± diazoxide, ± VU591 (Kir1.1 inhibitor), N = 9 to 23 each, 20 min), and Tyrode's (20 minutes). Isolated mouse (wild-type, sensitive regulatory subunit 1 [-/-], and cardiac knockout renal outer medullary potassium) hearts were given cardioplegia ± diazoxide (N = 9-16 each) before global ischemia (90 minutes) and 30 minutes reperfusion. Left ventricular pressures were compared before and after ischemia.

Results

Stress (cardioplegia) was associated with reduced myocyte contractility that was prevented by diazoxide. Isolated myocytes were not responsive to diazoxide in the presence of VU591. In isolated hearts, diazoxide improved left ventricular function after prolonged ischemia compared with cardioplegia alone in wild-type and knockout (sensitive regulatory subunit 1 [-/-] and cardiac knockout renal outer medullary potassium) mice.

Conclusions

Isolated myocyte and heart models may measure independent and separate actions of diazoxide. By definitive genetic deletion, these data indicate that sensitive regulatory subunit 1 and renal outer medullary potassium are not implicated in cardioprotection by diazoxide.

Usage Trends and Safety Profile of Recombinant Human Bone Morphogenetic Protein-2 for Spinal Column Tumor Surgery: A National Matched Cohort Analysis

STUDY DESIGN

Retrospective Cohort Analysis.

OBJECTIVE

The purpose of this study is to investigate national rates of rhBMP-2 utilization in spinal tumor surgery and examine its association with postoperative complications, revisions, and carcinogenicity.

METHODS

All patients diagnosed with primary or metastatic spinal tumors with subsequent surgical intervention involving a spinal fusion procedure were identified in PearlDiver. Patients were 1:1 matched into 2 cohorts according to rhBMP-2 usage. Postoperative complications and revisions were examined at 1 month, 3 months, 6 months, and 1 year after fusion. New cancer incidence following spinal tumor surgery was assessed until 5 years postoperatively.

RESULTS

A total of 11,198 patients underwent fusion surgery after resection of spinal tumors between 2005 and 2020, with 909 cases reporting the use of rhBMP-2 (8.1%). An annualized analysis revealed that the proportion of spine tumor fusion procedures utilizing rhBMP-2 has been significantly decreasing (R2 = .859, P < .001), with the most recent annual utilization rate at 1.1%. At least 3 months after surgery, significantly increased incidences of surgical site (11.4% vs 3.3%, P = .03) and systemic infections (8.1% vs 1.6%, P = .02) were observed in patients who underwent fusion with rhBMP-2. Across all time points, no significant differences were observed in survival, implant removal, revision rates, or new cancer diagnoses.

CONCLUSION

This analysis demonstrated significantly declining national utilization rates. Spinal tumor cases utilizing rhBMP-2 sustained greater rates of surgical site and systemic infections. rhBMP-2 usage did not significantly reduce the risk of mortality, implant failure, or reoperation.

Building Career Paths for Ph.D., Basic and Translational Scientists in Clinical Departments in the United States: An Official American Thoracic Society Workshop Report

Rationale: To identify barriers and opportunities for Ph.D., basic and translational scientists to be fully integrated into clinical units. Objectives: In 2022, an ad hoc committee of the American Thoracic Society developed a project proposal and workshop to identify opportunities and barriers for scientists who do not practice medicine to develop successful careers and achieve tenure-track faculty positions in clinical departments and divisions within academic medical centers (AMCs) in the United States. Methods: This document focuses on results from a survey of adult and pediatric pulmonary, critical care, and sleep medicine division chiefs as well as a survey of workshop participants, including faculty in departmental and school leadership roles in both basic science and clinical units within U.S. AMCs. Results: We conclude that full integration of non-clinically practicing basic and translational scientists into the clinical units, in addition to their traditional placements in basic science units, best serves the tripartite mission of AMCs to provide care, perform research, and educate the next generation. Evidence suggests clinical units do employ Ph.D. scientists in large numbers, but these faculty are often hired into non-tenure track positions, which do not provide the salary support, start-up funds, research independence, or space often associated with hiring in basic science units within the same institution. These barriers to success of Ph.D. faculty in clinical units are largely financial. Conclusions: Our recommendation is for AMCs to consider and explore some of our proposed strategies to accomplish the goal of integrating basic and translational scientists into clinical units in a meaningful way.

Connecting Biochemistry Knowledge to Patient Care in the Clinical Workplace: Senior Medical Students' Perceptions about Facilitators and Barriers

Phenomenon: Medical students have difficulties applying knowledge about biomedical mechanisms learned before clerkships to patient care activities. Many studies frame this challenge as a problem of basic science knowledge transfer predominantly influenced by students' individual cognitive processes. Social cognitive theory would support extending this framing to the interplay between the individual's cognition, the environment, and their behaviors. This study investigates senior medical students' experiences of biochemistry knowledge use during workplace learning and examines how their experiences were influenced by interactions with people and other elements of the clinical learning environment. Approach: The authors used a qualitative approach with a constructivist orientation. From September to November 2020 they conducted semi-structured interviews with 11 fourth-year medical students at one institution who had completed the pre-clerkship curriculum, core clinical clerkships, and the United States Medical Licensing Exam Step 1. The authors identified themes using thematic analysis. Findings: Participants reported that they infrequently used or connected to biochemistry knowledge in workplace patient care activities, yet all had examples of such connections that they found valuable to learning. Most participants felt the responsibility for making connections between biochemistry knowledge and activities in the clinical workplace should be shared between themselves and supervisors, but connections were often recognized and acted on only by the student. Connections that participants described prompted their effort to retrieve knowledge or fill a perceived learning gap. Participants identified multiple barriers and facilitators to connecting, including supervisors' behaviors and perceived knowledge, and "patients seen" in clerkships. Participants also reported learning biochemistry during USMLE Step 1 study that did not connect to patient care activities, underscoring a perception of disconnect. Insights: This study identifies specific personal, social, and physical environmental elements that influence students' perceived use of biochemistry during patient care activities. Though these findings may be most significant for biochemistry, they likely extend to other basic science disciplines. Students' self-directed efforts to connect to their biochemistry knowledge could be augmented by increased social support from clinical supervisors, which in turn likely requires faculty development. Opportunities for connection could be enhanced by embedding into the environment instructional strategies or technologies that build on known authentic connections between biochemistry and "patients seen" in clerkships. These efforts could strengthen student learning, improve clinical supervisors' self-efficacy, and better inform curriculum design.

Energy Metabolism Dysregulation in Chronic Kidney Disease

Key Points

There is significant enrichment in metabolic pathways in early stages in the subtotal nephrectomy model of CKD. Proximal tubular mitochondrial respiration is suppressed likely from mitochondrial dysfunction in substrate utilization and ATP synthesis. There is significant suppression of pyruvate dehydrogenase and increased glycolysis in proximal tubules.

Background

CKD is a significant contributor to morbidity and mortality. A better understanding of mechanisms underlying CKD progression is indispensable for developing effective therapies. Toward this goal, we addressed specific gaps in knowledge regarding tubular metabolism in the pathogenesis of CKD using the subtotal nephrectomy (STN) model in mice.

Methods

Weight- and age‐matched male 129X1/SvJ mice underwent sham or STN surgeries. We conducted serial GFR and hemodynamic measurements up to 16 weeks after sham and STN surgery and established the 4-week time point for subsequent studies.

Results

For a comprehensive assessment of renal metabolism, we conducted transcriptomic analyses, which showed significant enrichment of pathways involved in fatty acid metabolism, gluconeogenesis, glycolysis, and mitochondrial metabolism in STN kidneys. Expression of rate-limiting fatty acid oxidation and glycolytic enzymes was increased in STN kidneys, and proximal tubules in STN kidneys exhibited increased functional glycolysis but decreased mitochondrial respiration, despite an increase in mitochondrial biogenesis. Assessment of the pyruvate dehydrogenase complex pathway showed significant suppression of pyruvate dehydrogenase, suggesting decreased provision of acetyl CoA from pyruvate for the citric acid cycle to fuel mitochondrial respiration.

Conclusion

Metabolic pathways are significantly altered in response to kidney injury and may play an important role in the disease progression.

A Simple and Versatile Test for Elbow Posterolateral Rotatory Instability

BACKGROUND

Posterolateral rotatory instability (PLRI) results from lateral ulnar collateral ligament (LCL) deficiency. The lateral pivot shift test is used to diagnose PLRI but can be difficult to perform and is poorly tolerated. We present a new maneuver, the Posterior Radiocapitellar Subluxation Test (PRST), that we believe is easier to perform. The purpose of this study was to compare the efficacy and reproducibility of the PRST with the lateral pivot shift test.

METHODS

We obtained 10 cadaveric upper extremity specimens, performed a Kocher approach on each, released the LCL origin in 5, then closed. The specimens were randomized, and 3 attending orthopedic surgeons and 1 resident blindly performed the PRST then the lateral pivot shift test after re-randomization and assessed presence or absence of PLRI. This process was repeated the following day. The data for each test were analyzed for sensitivity, specificity, and accuracy.

RESULTS

For the blinded testing when comparing PRST with the pivot shift test, overall accuracy was 77.5%, compared with 67.5% (P = .03), sensitivity was 75.0%, compared with 50.0% (P = .003), and specificity was 80.0%, compared with 85.0% (P = .55). Conclusions: The PRST appears to be at least as accurate as the lateral pivot shift test, with comparable intraobserver and interobserver reliability.

Psychosocial Risk Stratification in Upper Extremity Transplantation Candidates

BACKGROUND

Candidate selection for upper extremity transplantation remains an inherently subjective process. This work evaluated the effect that psychosocial factors have on outcomes, both to standardize evaluation of potential candidates and in optimizing these factors prior to transplantation. Our goal was to measure and quantify the risk that various psychosocial factors have on transplant outcomes.

METHODS

Given that we do not have sufficient post-transplant patients to examine specific factors, we chose to have experts in the field evaluate hypothetical patients based on their experience. We used a Generalized Estimating Equation to estimate and compare surgical candidacy scores using patient scenario vignettes based on the presence or absence of permutations of the following: (1) depression; (2) participation in occupational therapy (OT); (3) expectation of post-transplant function; (4) punctuality; and (5) family support were given to experts in the field.

RESULTS

This work suggests there is a decrease in predicted success with increasing numbers of negative factors with participation in OT and realistic expectations of outcomes being most important. An increase in the summarizing risk score from 0 to 1.7 was associated with a decrease in the outcome surgical candidacy score from 8.6 to 5.3, meaning candidates with 2 risk factors would often observe a large drop in surgical candidacy score.

CONCLUSIONS

Focusing on optimizing psychosocial variables in transplant candidates may help improve hand transplant success.

CyclosporinA Derivative as Therapeutic Candidate for Alport Syndrome by Inducing Mutant Type IV Collagen Secretion

Key Points

Screening of natural product extracts to find candidate compounds that increase mutant type IV collagen α 3,4,5 (α 345(IV)) trimer secretion in Alport syndrome (AS). Cyclosporin A (CsA) and alisporivir (ALV) increase mutant α 345(IV) trimer secretion in AS. PPIF/cyclophilin D mediates the effect of CsA and ALV on mutant trimer secretion.

Background

Type IV collagen α 3,4,5 (α 345(IV)) is an obligate trimer that is secreted to form a collagen network, which is the structural foundation of basement membrane. Mutation in one of the genes (COL4A3 , A4 , A5 ) encoding these proteins underlies the progressive genetic nephropathy Alport syndrome (AS) due to deficiency in trimerization and/or secretion of the α 345(IV) trimer. Thus, improving mutant α 345(IV) trimerization and secretion could be a good therapeutic approach for AS.

Methods

Using the nanoluciferase-based platform that we previously developed to detect α 345(IV) formation and secretion in HEK293T cells, we screened libraries of natural product extracts and compounds to find a candidate compound capable of increasing mutant α 345(IV) secretion.

Results

The screening of >13,000 extracts and >600 compounds revealed that cyclosporin A (CsA) increased the secretion of mutant α 345(IV)-G1244D. To elucidate the mechanism of the effect of CsA, we evaluated CsA derivatives with different ability to bind to calcineurin (Cn) and cyclophilin (Cyp). Alisporivir (ALV), which binds to Cyp but not to Cn, increased the trimer secretion of mutant α 345(IV). Knockdown studies on Cyps showed that PPIF/cyclophilin D was involved in the trimer secretion-enhancing activity of CsA and ALV. We confirmed that other α 345(IV) mutants are also responsive to CsA and ALV.

Conclusions

CsA was previously reported to improve proteinuria in patients with AS, but owing to its nephrotoxic effect, CsA is not recommended for treatment in patients with AS. Our data raise the possibility that ALV could be a safer option than CsA. This study provides a novel therapeutic candidate for AS with an innovative mechanism of action and reveals an aspect of the intracellular regulatory mechanism of α 345(IV) that was previously unexplored.

Canal Fill of the Forearm Bones When Placing Intramedullary Nails in the Pediatric and Adolescent Populations

BACKGROUND

In the lower extremity, studies have suggested an optimal nail diameter to medullary canal diameter (ND/MCD) ratio to minimize postoperative complications. The goal of this study was to determine whether a correlation exists between the occurrence of complications, angulation, and range of motion and the ratio of the ND/MCD in the upper extremity.

METHODS

A total of 85 radius and ulna fractures treated with flexible intramedullary nails had ND/MCD ratios measured. Random-effects models were developed to determine the association between complications and ND/MCD ratio, angulation and ND/MCD ratio, and range of motion and ND/MCD ratio. The results were reported for unadjusted models and adjusted models.

RESULTS

Of the 85 forearm fractures treated with intramedullary nailing, there were 3 complications. The average follow-up was 6 months. The ND/MCD ratios were categorized as <0.50, 0.50 to 0.59, and ≥0.60. There was not a significant association between the different ratios and angulation, or risk of complication. There was an association between the ND/MCD ratio ≥0.60 and decreased pronation of -1.58° (-2.77° to -0.38°) and supination of -2.68° (-4.91° to -0.46°) (P < .05).

CONCLUSION

This study found that there was not an association between the nail to canal diameter ratio and postoperative angulation in forearm fractures treated with flexible intramedullary nails. When choosing a flexible nail for forearm fractures, there does not appear to be an optimal ratio; it is therefore reasonable to use the ND that passes more easily.

The Transosseous Internal Four Strand Technique: A New All-Inside Technique for Zone 1 Flexor Tendon Repairs

BACKGROUND

Multiple techniques for the repair of flexor tendon injuries in zone 1 have been proposed over time. While pull-out suture techniques and bone anchor seem to be stronger than internal suture techniques, they are associated with a higher complication rate. We therefore developed an alternative internal suture repair with similar biomechanical stability to those of pull-out sutures and bone anchors.

METHODS

Twenty porcine distal phalanges and deep flexor tendons were randomized to 2 groups of 10 each. The tendons were transsected at the level of the distal interphalangeal joint. In group 1, repairs were performed with a well-established intraosseous suture repair and in group 2 with our new multistrand technique. The repairs were biomechanically tested with linear distraction until failure.

RESULTS

We recorded a significantly higher 2-mm gap force (2GF)-and thus higher stability-of the repairs in group 1 in comparison to group 2. With a 2GF of more than 50 N, our suture technique allows for a modern early active motion rehabilitation protocol. Breakage of the suture construct occurred at random places in the repair in both groups. No pull-outs were noted.

CONCLUSIONS

This study presents a strong transosseous multistrand repair technique for flexor tendon repair in zone 1 that is simple and fast to perform and should have enough strength to withstand early active motion rehabilitation.

Orthopaedic infections: what have we learned?

Orthopaedic infections remain challenging complications to treat, with profound economic impact in addition to patient morbidity. The overall estimates of infection after orthopaedic surgery with internal devices has been estimated at 5%, with hospital costs eight times that of those without fracture-related infections and with significantly poorer functional and pain interference PROMIS scores. Orthopaedic infection interventions have been focused on prevention and treatment options. The creation of new modalities for orthopaedic infection treatment can benefit from the understanding of the temporal relationship between bacterial colonization and host-cell integration, a concept referred to as "the race for the surface." Regarding prevention, host modulation and antibiotic powder use have been explored as viable options to lower infection rates. Orthopaedic infection treatment has additionally continued to evolve, with PO antibiotics demonstrating equivalent efficacy to IV antibiotics for the treatment of orthopaedic infections in recent studies. In conclusion, orthopaedic infections remain difficult clinical dilemmas, although evolving prevention and treatment modalities continue to emerge.

Lrpap1 (RAP) Inhibits Proximal Tubule Clathrin Mediated and Clathrin Independent Endocytosis, Ameliorating Renal Aminoglycoside Nephrotoxicity

Key Points

Proximal tubule endocytosis of toxins often leads to nephrotoxicity. Inhibition of endocytosis with receptor-associated protein may serve as a clinical approach to reduce or eliminate kidney damage from a potential nephrotoxin.

Background

Proximal tubules (PTs) are exposed to many exogenous and endogenous nephrotoxins that pass through the glomerular filter. This includes many small molecules, such as aminoglycoside and myeloma light chains. These filtered molecules are rapidly endocytosed by the PTs and lead to nephrotoxicity.

Methods

To investigate whether inhibition of PT uptake of filtered toxins can reduce toxicity, we evaluated the ability of Lrpap1 or receptor-associated protein (RAP) to prevent PT endocytosis. Munich Wistar Frömter rats were used since both glomerular filtration and PT uptake can be visualized and quantified. The injury model chosen was the well-established gentamicin-induced toxicity, which leads to significant reductions in GFR and serum creatinine increases. CKD was induced with a right uninephrectomy and left 40-minute pedicle clamp. Rats had 8 weeks to recover and to stabilize GFR and proteinuria. Multiphoton microscopy was used to evaluate endocytosis in vivo and serum creatinine, and 24-hour creatinine clearances were used to evaluate kidney functional changes.

Results

Studies showed that preadministration of RAP significantly inhibited both albumin and dextran endocytosis in outer cortical PTs. Importantly, this inhibition was found to be rapidly reversible with time. RAP was also found to be an excellent inhibitor of PT gentamicin endocytosis. Finally, gentamicin administration for 6 days resulted in significant elevation of serum creatinine in vehicle-treated rats, but not in those receiving daily infusion of RAP before gentamicin.

Conclusions

This study provides a model for the potential use of RAP to prevent, in a reversible manner, PT endocytosis of potential nephrotoxins, thus protecting the kidney from damage.

Fracture healing-orthobiologics: from basic science to clinical application

Orthopaedics as a field and a profession is fundamentally concerned with the treatment of musculoskeletal disease, in all of its many forms. Our collective understanding of the cellular mechanisms underlying musculoskeletal pathology resulting from injury continues to evolve, opening novel opportunities to develop orthobiologic treatments to improve care. It is a long path to move from an understanding of cellular pathology to development of successful clinical treatment, and this article proposes to discuss some of the challenges to achieving translational therapies in orthopaedics. The article will focus on challenges that clinicians will likely face in seeking to bring promising treatments forward to clinical practice and strategies for improving success in translational efforts.

Area Deprivation Index Is Not Associated With the Severity of Carpal Tunnel Syndrome

BACKGROUND

While living in a socially disadvantaged neighborhood is linked with numerous health outcomes, its effect on patient-reported outcome scores and diagnostic measures in carpal tunnel syndrome (CTS) is not fully understood. This study examines the effect of neighborhood socioeconomic deprivation on CTS severity as measured by the Boston Carpal Tunnel Questionnaire (BCTQ), 6-item Carpal Tunnel Symptoms Scale (CTS-6), and diagnostic testing modalities.

METHODS

This was a retrospective analysis of patients who presented to the hand clinic at a single hospital system with symptoms consistent with CTS. Ultrasound cross-sectional area (CSA) of the median nerve, CTS-6, Symptom Severity Scale (SSS) and Functional Status Scale (FSS) of the BCTQ, and the Area Deprivation Index (ADI) national rank percentile were collected. Patients were grouped into 4 quartiles based on their ADI national percentile. Analyses of variance (ANOVAs) were conducted to test for statistical differences between the 4 quartiles based on the average values of median nerve CSA, CTS-6, SSS, and FSS score. The bottom quartile was compared with the upper 75% of the sample (26th-100th percentile) and to the upper quartile via Student t test. Statistical significance was set at P < .05.

RESULTS

Analyses of variance revealed no statistically significant differences between the 4 quartiles for either median nerve CSA, CTS-6, SSS, or FSS. When comparing the bottom quartile with the upper 75% of the sample and the upper quartile, no significant statistical differences were identified.

CONCLUSIONS

No relationships were found between social deprivation (ADI) and patient-reported outcomes, CTS-6 scores, or median nerve CSA.

Computed Tomography Neurography for Visualization of the In Vivo Nervous System: A Proof of Concept

BACKGROUND

The human peripheral nervous system embodies anatomical, physiologic, and diagnostic perplexities that remain unexplained. Yet in the course of human history, there are no mechanisms, such as computed tomography (CT) or radiography, by which to image the peripheral nervous system in vivo using a contrast agent that is identified by ionizing radiation, which would aid in surgical navigation, diagnostic radiology, and basic science thereof.

METHODS

A novel class of contrast was created by linking iodine to lidocaine. The radiodensity of 0.5% experimental contrast molecule was compared with a control of 1% lidocaine by placing 1.5-mL aliquots of each liquid into centrifuge tubes and performing micro-computed tomography (micro-CT) synchronously under identical settings. Physiologic binding to the sciatic nerve was evaluated by injecting 10 mg of the experimental contrast and 10 mg of the control into the contralateral sciatic nerve, and documenting loss of hindlimb function and recovery. In vivo visualization of the sciatic nerve was evaluated by injecting 10 mg of experimental contrast or control into either sciatic nerve and imaging the hindlimbs under identical conditions using micro-CT.

RESULTS

The mean Hounsfield unit of the contrast was 56.09 compared with -0.48 for control (116-fold increase, P = .0001). Hindlimb paresis revealed similar degree of paresis, baseline recovery, and time to recovery. In vivo enhancement between the contralateral sciatic nerves was similar.

CONCLUSION

Iodinated lidocaine offers a viable mechanism for in vivo peripheral nerve imaging using CT; however, it requires modification to improve in vivo radiodensity.

Students' Perspectives on Basic and Clinical Science Integration When Step 1 is Administered After the Core Clerkships

Phenomenon: According to adult learning theories, effective cognitive integration of basic and clinical science may promote the transfer of knowledge to patient care. The placement of the U.S. Medical Licensing Examination (USMLE) Step 1 after the core clerkships is one strategy intended to facilitate cognitive integration, though learner experiences with this model are unexplored. The purpose of this study is to understand students' perspectives on basic and clinical science integration in a post-clerkship Step 1 curriculum. Approach: Focus groups were conducted between August and September 2020 with senior medical students from the University of California, San Francisco School of Medicine and University of Michigan Medical School. Data were analyzed using a constructivist approach to thematic analysis. Findings: Thirty-three students participated in six focus groups. Participants described multiple barriers to cognitive integration in the clerkship learning environment, though they also identified examples of teaching and learning that facilitated integration. Early in their clerkships, students struggled to integrate because of their tenuous basic science foundation, cognitive overload, and difficulty perceiving the relevance of basic science to patient care. They felt that educators primarily focused on clinical science, and many basic science teaching sessions during clerkships felt irrelevant to patient care. However, students also described experiences that made the connection between basic and clinical science more explicit, including modeling by educators and clerkship learning activities that more overtly encouraged the application of basic science to clinical care. In addition, the return to basic science studying during the post-clerkship dedicated Step 1 study period offered powerful integration opportunities. These facilitators of cognitive integration helped students recognize the value of integration for enduring learning. Insights: There are myriad barriers to cognitive integration of basic and clinical science during clerkships in a post-clerkship Step 1 curriculum. The relevance of basic science to patient care needs to be made more explicit to students through modeling by clinician educators to augment the potential benefits of curricular change. The post-clerkship Step 1 study period appears to offer a unique opportunity for cognitive integration later in a learner's trajectory that may be related to curricular design. When learners recognize the applicability of basic science to patient care, they may more intentionally transfer basic science knowledge to clinical practice.

Modulating T Cell Phenotype and Function to Treat Hypertension

Hypertension is the leading modifiable risk factor of worldwide morbidity and mortality because of its effects on cardiovascular and renal end-organ damage. Unfortunately, BP control is not sufficient to fully reduce the risks of hypertension, underscoring the need for novel therapies that address end-organ damage in hypertension. Over the past several decades, the link between immune activation and hypertension has been well established, but there are still no therapies for hypertension that specifically target the immune system. In this review, we describe the critical role played by T cells in hypertension and hypertensive end-organ damage and outline potential therapeutic targets to modulate T-cell phenotype and function in hypertension without causing global immunosuppression.

Effect of PARP-1 Inhibition on Rotator Cuff Healing: A Feasibility Study Using Veliparib in a Rat Model of Acute Rotator Cuff Repair

BACKGROUND

PARP-1 (poly[ADP-ribose]) was shown to influence the inflammatory response after rotator cuff tear, leading to fibrosis, muscular atrophy, and fatty infiltration in mouse rotator cuff degeneration. So far, it is not known how PARP-1 influences enthesis healing after rotator cuff tear repair.

HYPOTHESIS/PURPOSE

This study aimed to examine the feasibility of oral PARP-1 inhibition and investigate its influence on rat supraspinatus enthesis and muscle healing after rotator cuff repair. The hypothesis was that oral PARP-1 inhibition would improve enthesis healing after acute rotator cuff repair in a rat model.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 24 Sprague-Dawley rats, the supraspinatus tendon was sharply detached and immediately repaired with a single transosseous suture. The rats were randomly allocated into 2 groups, with the rats in the inhibitor group receiving veliparib with a target dose of 12.5 mg/kg/d via drinking water during the postoperative recovery period. The animals were sacrificed 8 weeks after surgery. For the analysis, macroscopic, biomechanical, and histologic methods were used.

RESULTS

Oral veliparib was safe for the rats, with no adverse effects observed. In total, the inhibitor group had a significantly better histologic grading of the enthesis with less scar tissue formation. The macroscopic cross-sectional area of the supraspinatus muscles was 10.5% higher (P = .034) in the inhibitor group, which was in agreement with an 8.7% higher microscopic muscle fiber diameter on histologic sections (P < .0001). There were no statistically significant differences in the biomechanical properties between the groups.

CONCLUSION

This study is the first to investigate the influence of PARP-1 inhibition on healing enthesis. On the basis of these findings, we conclude that oral veliparib, which was previously shown to inhibit PARP-1 effectively, is safe to apply and has beneficial effects on morphologic enthesis healing and muscle fiber size.

CLINICAL RELEVANCE

Modulating the inflammatory response through PARP-1 inhibition during the postoperative healing period is a promising approach to improve enthesis healing and reduce rotator cuff retearing. With substances already approved by the Food and Drug Administration, PARP-1 inhibition bears high potential for future translation into clinical application.