Impact of the Multiple Sclerosis-Associated Genetic Variant CD226 Gly307Ser on Human CD8 T-Cell Functions.

BACKGROUND AND OBJECTIVES: The rs763361 nonsynonymous variant in the CD226 gene, which results in a glycine-to-serine substitution at position 307 of the CD226 protein, has been implicated as a risk factor of various immune-mediated diseases, including multiple sclerosis (MS). Compelling evidence suggests that this allele may play a significant role in predisposing individuals to MS by decreasing the immune-regulatory capacity of Treg cells and increasing the proinflammatory potential of effector CD4 T cells. However, the impact of this CD226 gene variant on CD8 T-cell functions, a population that also plays a key role in MS, remains to be determined. METHODS: To study whether the CD226 risk variant affects human CD8 T-cell functions, we used CD8 T cells isolated from peripheral blood mononuclear cell of 16 age-matched healthy donors homozygous for either the protective or the risk allele of CD226. We characterized these CD8 T cells on T-cell receptor (TCR) stimulation using high-parametric flow cytometry and bulk RNAseq and through characterization of canonical signaling pathways and cytokine production. RESULTS: On TCR engagement, the phenotype of ex vivo CD8 T cells bearing the protective (CD226-307Gly) or the risk (CD226-307Ser) allele of CD226 was largely overlapping. However, the transcriptomic signature of CD8 T cells from the donors carrying the risk allele presented an enrichment in TCR, JAK/STAT, and IFNγ signaling. We next found that the CD226-307Ser risk allele leads to a selective increase in the phosphorylation of the mitogen-activated protein kinases extracellular signal-regulated kinases 1 and 2 (ERK1/2) associated with enhanced phosphorylation of STAT4 and increased production of IFNγ. DISCUSSION: Our data suggest that the CD226-307Ser risk variant imposes immune dysregulation by increasing the pathways related to IFNγ signaling in CD8 T cells, thereby contributing to the risk of developing chronic inflammation.

Stool-based testing for post-polypectomy colorectal cancer surveillance safely reduces colonoscopies: The MOCCAS study.

BACKGROUND AND AIMS: Colonoscopy-based surveillance to prevent colorectal cancer (CRC) causes substantial burden for patients and healthcare. Stool tests may help to reduce surveillance colonoscopies, by limiting colonoscopies to individuals at increased risk of AN. METHODS: This cross-sectional observational study included individuals aged 50-75 with surveillance indication. Before bowel preparation, participants collected samples for a multitarget stool DNA (mt-sDNA) test and two fecal immunochemical tests (FITs). Test accuracies were calculated for all surveillance indications. Only for the post-polypectomy indication, most common and associated with a relatively low CRC risk, long-term impact of stool-based surveillance was evaluated with the ASCCA model. Stool-based strategies were simulated to tune each tests' positivity threshold to obtain strategies at least as effective as colonoscopy surveillance. RESULTS: 3453 individuals had results for all stool tests and colonoscopy. 2226 had previous polypectomy, 1003 previous CRC and 224 familial risk. Areas under the receiver operating characteristic curve for AN were 0.72 (95% CI; 0.69-0.75) for the mt-sDNA test, 0.61 (95% CI; 0.58-0.64) for the FIT OC-Sensor and 0.59 (95% CI; 0.56-0.61) for the FIT FOB-Gold. Stool-based post-polypectomy surveillance strategies at least as effective as colonoscopy surveillance, reduced the number of colonoscopies by 15-41% and required 5.6-9.5 stool tests over the lifetime of a person. Mt-sDNA-based surveillance was more costly than colonoscopy surveillance, whereas FIT-based surveillance saved costs. CONCLUSIONS: This study shows that stool-based post-polypectomy surveillance strategies can be safe and cost-effective, with potential to reduce the number of colonoscopies by up to 41%.

Discovery of Lacto-N-biosidases and a Novel N-Acetyllactosaminidase Activity in the CAZy Family GH20: Functional Diversity and Structural Insights.

The glycoside hydrolase family 20 (GH20) predominantly features N-acetylhexosaminidases (EC 3.2.1.52), with only few known lacto-N-biosidases (EC 3.2.1.140; LNBases). LNBases catalyze the degradation of lacto-N-tetraose (LNT), a prominent component of human milk oligosaccharides, thereby supporting a healthy infant gut microbiome development. We investigated GH20 diversity to discover novel enzymes that release disaccharides such as lacto-N-biose (LNB). Our approach combined peptide clustering, sequence analysis, and 3D structure model evaluation to assess active site topologies, focusing on the presence of a subsite -2. Five LNBases were active on pNP-LNB and four showed activity on LNT. One enzyme displayed activity on both pNP-LacNAc and pNP-LNB, establishing the first report of N-acetyllactosaminidase (LacNAcase) activity. Exploration of this enzyme cluster led to the identification of four additional enzymes sharing this dual substrate specificity. Comparing the determined crystal structure of a specific LNBase (TrpyGH20) and the first crystal structure of an enzyme with dual LacNAcase/LNBase activity (TrdeGH20) revealed a highly conserved subsite -1, common to GH20 enzymes, while the -2 subsites varied significantly. TrdeGH20 had a wider subsite -2, accommodating Gal with both ß1,4- and ß1,3-linkages to the GlcNAc in subsite -1. Biotechnological applications of these enzymes may include structural elucidation of complex carbohydrates and glycoengineering.

Nutrition intake, muscle thickness, and recovery outcomes for critically ill patients requiring non-invasive forms of respiratory support: A prospective observational study.

BACKGROUND: Use of high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) in the intensive care unit (ICU) is increasing, yet reporting of nutrition intake, muscle thickness, or recovery outcomes in this population is limited. OBJECTIVE: The objective of this study was to quantify muscle thickness, nutrition intake, and functional recovery outcomes for patients receiving HFNC/NIV within the ICU. METHODS: A single-centre, prospective, observational study in adult ICU patients recruited within 48 hrs of commencing HFNC/NIV. Change in quadriceps muscle layer thickness using ultrasound (primary outcome) and 24 hr nutrition intake from study inclusion to day 7 (D7), functional capacity (Barthel Index), and quality of life (EuroQol five-dimension five-level utility index) at D90 were assessed. Data are n (%), mean ± standard deviation or median [interquartile range], are compared using paired sample t-test, and a P value of <0.05 was considered significant. RESULTS: Primary outcome data were available for n = 28/42: 64 ± 13 y, 61% male, body mass index: 29.1 ± 9.0 kg/m2, and Acute Physiology and Chronic Health Evaluation II score: 17 ± 5. Quadriceps muscle layer thickness reduced from 2.41 ± 0.87 to 2.12 ± 0.73 cm; mean difference: -0.29 cm (95% confidence interval: -0.44, -0.13). Nutrition intake increased from study inclusion to D7: 1735 ± 1283 to 5448 ± 2858 kJ and 17.4 ± 16.6 to 60.9 ± 36.8g protein. Barthel Index was 87 ± 20 at baseline and 91 ± 15 at D90 (out of 100). Quality of life was impaired at D90: 0.64 ± 0.23 (health = 1.0). CONCLUSION: Critically ill patients receiving HFNC/NIV experienced muscle loss and impaired quality of life.

Optimal Medical Therapy and Outcomes Among Patients With Chronic Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Optimal medical therapy (OMT) scoring may stratify clinical risk in real-world chronic heart failure with reduced ejection fraction (HFrEF) by integrating use and dosing of guideline-directed medical therapy (GDMT) for HFrEF. OBJECTIVES: The purpose of this study was to characterize patients and associated long-term clinical outcomes by OMT score-derived treatment groups. METHODS: CHAMP-HF (Change the Management of Patients with Heart Failure) included U.S. outpatients with chronic HFrEF receiving ≥1 GDMT. OMT subgroups were defined as suboptimal (score <3), acceptable (score = 3), and optimal (score ≥4) by baseline use and dose of GDMT, as proposed by the HF Collaboratory consortium. Cox proportional hazard analyses were used to assess for all-cause and cardiovascular death across subgroups, after adjusting for demographic and clinical covariates. RESULTS: The authors studied 4,582 participants enrolled in CHAMP-HF with available 2-year follow-up. Median age was 68 years, 1,327 (29%) were women, and 2,842 (62%) were White, non-Hispanic. Median OMT score across the population was 4 (Q1-Q3: 2-5), and 1,628 (35%) had suboptimal, 665 (14%) had acceptable, and 2,289 (50%) had optimal therapy. Participants with optimal treatment were younger, had higher annual household income, and were enrolled from practices with dedicated HF clinics (all P < 0.001) than participants with acceptable or suboptimal treatment. Participants with optimal treatment had lower all-cause death (adjusted HR: 0.77; 95% CI: 0.64-0.92) and cardiovascular death (adjusted HR: 0.79; 95% CI: 0.65-0.96) than those with suboptimal treatment. CONCLUSIONS: Across a large cohort of chronic ambulatory HFrEF, OMT scores stratified risk of all-cause and cardiovascular death.

Assessing the immunogenicity risk of salmon calcitonin peptide impurities using in silico and in vitro methods.

Advances in synthetic peptide synthesis have enabled rapid and cost-effective peptide drug manufacturing. For this reason, peptide drugs that were first produced using recombinant DNA (rDNA) technology are now being produced using solid- and liquid-phase peptide synthesis. While peptide synthesis has some advantages over rDNA expression methods, new peptide-related impurities that differ from the active pharmaceutical ingredient (API) may be generated during synthesis. These impurity byproducts of the original peptide sequence feature amino acid insertions, deletions, and side-chain modifications that may alter the immunogenicity risk profile of the drug product. Impurities resulting from synthesis have become the special focus of regulatory review and approval for human use, as outlined in the FDA's Center for Drug Evaluation and Research guidance document, "ANDAs for Certain Highly Purified Synthetic Peptide Drug Products That Refer to Listed Drugs of rDNA Origin," published in 2021. This case study illustrates how in silico and in vitro methods can be applied to assess the immunogenicity risk of impurities that may be present in synthetic generic versions of the salmon calcitonin (SCT) drug product. Sponsors of generic drug abbreviated new drug applications (ANDAs) should consider careful control of these impurities (for example, keeping the concentration of the immunogenic impurities below the cut-off recommended by FDA regulators). Twenty example SCT impurities were analyzed using in silico tools and assessed as having slightly more or less immunogenic risk potential relative to the SCT API peptide. Class II human leukocyte antigen (HLA)-binding assays provided independent confirmation that a 9-mer sequence present in the C-terminus of SCT binds promiscuously to multiple HLA DR alleles, while T-cell assays confirmed the expected T-cell responses to SCT and selected impurities. In silico analysis combined with in vitro assays that directly compare the API to each individual impurity peptide may be a useful approach for assessing the potential immunogenic risk posed by peptide impurities that are present in generic drug products.

Mini-Review: The Distinct Carbohydrate Active Enzyme Secretome of Rhizopus spp. Represents Fitness for Mycelium Remodeling and Solid-State Plant Food Fermentation.

Rhizopus is a genus of filamentous fungi belonging to the Mucoromycota division. Rhizopus species produce a white, dense mycelium, which is used to create tempeh, a solid-state fermented Asian soybean product, that is gaining renewed attention as a proteinaceous plant food. The profile of carbohydrate-active enzymes (CAZymes) of a fungus or group of fungi, particularly the secretome CAZymes profile, reflects adaptation to different lifestyles and habitats, and has a significant impact on fermentative capacity. This review examines the CAZymes profiles of Rhizopus species focusing on their implication for carbohydrate utilization and solid-state fermentation of plant materials. Through comprehensive genomic assessments and comparisons with other filamentous fungi, we particularly highlight how the unique CAZymes secretome profile is closely correlated with the taxonomy and ecological niches of Rhizopus species. We discuss how the CAZymes secretome capacity of Rhizopus species differs from other fungi and summarize the current state of knowledge regarding the specific CAZymes involved in the modification of carbohydrates in the fungal cell wall and in plant cell walls. We foresee that advanced genomic and proteomic technologies will be used to expand the biotechnology applications of Rhizopus spp.

Robotic Resection of Spinal and Paraspinal Tumors.

BACKGROUND AND OBJECTIVES: Robotic arm surgical systems provide minimally invasive access and are commonly used in multiple surgical fields, with limited application in neurosurgery. Our institutional experience has led us to explore the benefits of a neurosurgeon trained to perform robotic surgery as part of a multidisciplinary team. The objective of this study is to evaluate the feasibility, safety, and outcomes of robotic resection for spinal nerve sheath tumors (NST). METHODS: Retrospective case series of robotic-assisted intracavitary approaches and resection of NSTs including thoracic, retroperitoneal, and transperitoneal. Surgical outcomes are compared to a historical cohort of open surgical resection of NSTs. RESULTS: Nineteen cases presented, of which 2 were combined posterior spinal followed by robotic tumor resection. One of 19 cases was converted to an open surgery. Gross total resection was achieved in all cases. There were 2 cases of postoperative Horner's syndrome, and 1 case with an intraoperative durotomy that was repaired primarily with no postoperative sequelae. Median estimated blood loss was 50 cc (range: 5-650) and median length of stay was 1 day (range: 0-6), with 9 (47.4%) patients discharged on postoperative day 1 and 3 (15.8%) patients discharged on an outpatient basis. Compared with our previously reported institutional outcomes for open resection of 25 tumors, there was a significant increase in rates of gross total resection (100 vs 60%, P = .002) and decrease in length of stay (median 1 vs 5 days, P < .0001). CONCLUSION: Robotic resection of complex paraspinal tumors appears safe and effective including for preservation of neurological function and may reduce surgical morbidity. Integration of robotic surgical platforms holds the potential to significantly affect neurological surgery.

Evaluating physiological barriers to oral intake in hospitalized patients: A secondary analysis.

BACKGROUND: Oral intake in hospitalized patients is frequently below estimated targets. Multiple physiological symptoms are proposed to impact oral intake, yet many have not been quantified objectively. AIM: To describe the challenges of objectively measuring physiological nutrition-impacting symptoms in hospitalized patients. METHOD: A secondary analysis of data from a single-center, descriptive cohort study of physiological nutrition-impacting symptoms in intensive care unit (ICU) survivors and general medical patients was conducted. Demographic and clinical characteristics were extracted for patients who completed the original study and collected retrospectively for those who were screened and recruited but did not complete the original study. Reasons for patient exclusion from the original study were quantified from the screening database. Descriptive data are reported as mean ± SD, median [interquartile range], or number (percentage). RESULTS: ICU survivors and general medical patients were screened for inclusion in the original study between March 1 and December 23, 2021. Of the 644 patients screened, 97% did not complete the study, with 93% excluded at screening. Of the 266 ICU survivors and 398 general medical patients screened, 89% and 95% were excluded, respectively. Major exclusion criteria included the inability to follow commands or give informed consent (n = 155, 25%), the inability to consume the easy-to-chew and thin-fluid buffet meal, and imminent discharge (both, n = 120, 19%). CONCLUSION: Understanding physiological factors that drive reduced oral intake in hospitalized patients is challenging. Exclusion criteria required to objectively quantify physiological nutrition-impacting symptoms significantly preclude participation and likely act as independent barriers to oral intake.

Leveraging Immunofocusing and Virus-like Particle Display to Enhance Antibody Responses to the Malaria Blood-Stage Invasion Complex Antigen PfCyRPA.

A vaccine protecting against malaria caused by Plasmodium falciparum is urgently needed. The blood-stage invasion complex PCRCR consists of the five malarial proteins PfPTRAMP, PfCSS, PfRipr, PfCyRPA, and PfRH5. As each subcomponent represents an essential and highly conserved antigen, PCRCR is considered a promising vaccine target. Furthermore, antibodies targeting the complex can block red blood cell invasion by the malaria parasite. However, extremely high titers of neutralizing antibodies are needed for this invasion-blocking effect, and a vaccine based on soluble PfRH5 protein has proven insufficient in inducing a protective response in a clinical trial. Here, we present the results of two approaches to increase the neutralizing antibody titers: (A) immunofocusing and (B) increasing the immunogenicity of the antigen via multivalent display on capsid virus-like particles (cVLPs). The immunofocusing strategies included vaccinating with peptides capable of binding the invasion-blocking anti-PfCyRPA monoclonal antibody CyP1.9, as well as removing non-neutralizing epitopes of PfCyRPA through truncation. Vaccination with PfCyRPA coupled to the AP205 cVLP induced nearly two-fold higher IgG responses compared to vaccinating with soluble PfCyRPA protein. Immunofocusing using a linear peptide greatly increased the neutralizing capacity of the anti-PfCyRPA antibodies. However, significantly lower total anti-PfCyRPA titers were achieved using this strategy. Our results underline the potential of a cVLP-based malaria vaccine including full-length PfCyRPA, which could be combined with other leading malaria vaccine antigens presented on cVLPs.

Impact of combining dental composite brushes with modeling resins on the color stability and topographic features of composites.

This study explores the effect of using dental brushes with or without metacrylate-based modeling resins on long-term color stability and surface topographies of resin-based composites. This study examined the effects of two variables: (1) the type of brush used (Art brush, Micro-brush, or Mylar strip) and (2) the application of a modeling resin (applied or not applied). The specimens were artificially aged through 10,000 cycles of thermocycling and subsequently immersed in coffee for 30 days. Measurements of color and surface roughness were taken at baseline and after the aging, using a non-contact profilometer for surface roughness and a spectrophotometer for color. Data were analyzed using paired t-tests and one-way ANOVA. Resin-based composites smoothed with dental brushes or micro brushes without modeling resins exhibited lower color change (ΔE) than other groups. Paired t-tests revealed significant differences in average surface roughness (Ra) and valley depth (Rv) for each surfacing technique before and after aging (p ⩽ 0.01). The root means square average of the profile heights (Rq) significantly increased in the control and micro-brush groups (p ⩽ 0.01). In conclusion, the use of brushes in resin-based composites placement does not increase the susceptibility to staining. Instead, the inclusion of resin modeling contributes to discoloration over time.

Dietary protein in the ICU in relation to health outcomes.

PURPOSE OF REVIEW: Critical care nutrition guidelines recommend provision of higher protein doses than recommended in health. These recommendations have been predominately based on lower quality evidence and physiological rationale that greater protein doses may attenuate the significant muscle loss observed in critically ill patients. This review discusses the mechanistic action of protein in the critically ill, details results from recent trials on health outcomes, discusses considerations for interpretation of trial results, and provides an overview of future directions. RECENT FINDINGS: Two recent large clinical trials have investigated different protein doses and the effect on clinical outcome. Important findings revealed potential harm in certain sub-groups of patients. This harm must be balanced with the potential for beneficial effects on muscle mass and physical function given that two recent systematic reviews with meta-analyses demonstrated attenuation of muscle loss with higher protein doses. Utilizing biological markers such as urea: creatinine ratio or urea levels may prove useful in monitoring harm from higher protein doses. SUMMARY: Future research should focus on prospectively investigating biological signatures of harm as well as taking into the consideration elements that will likely enhance the effectiveness of protein dose.

Restoration with a posterior CAD/CAM onlay after failure of a direct resin-based composite restoration: a case report.

A conservative approach to restoration assists in preserving the remaining tooth structure of extensively destroyed vital teeth. This case report describes a single-appointment chairside technique for placement of ceramic restorations in posterior teeth. A patient presented for treatment of her mandibular right first molar, which had a fractured resin-based composite restoration. Due to the presence of vital pulp, extent of the restoration, and presence of caries in the tooth, the following treatment plan was proposed: placement of a lithium disilicate glass-ceramic onlay fabricated with a computer-aided design/computer-aided manufacturing workflow. After the dentist removed the restoration and performed selective caries removal, structural analysis guided the reduction of the buccal cusps. Immediate dentin sealing was performed with a 2-step self-etching adhesive system, and a 1-mm-thick layer of flowable resin-based composite was placed as a resin coating. A digital impression was obtained, the onlay restoration was designed, and a lithium disilicate block was milled and subsequently crystallized. When the onlay was completed, the tooth preparation was sandblasted, selectively etched, and coated with a universal adhesive. The intaglio surface of the onlay was cleaned and primed, the onlay was bonded with dual-cure resin cement, and occlusal adjustments were completed. Follow-up examinations at 1 and 4 months revealed the clinical success of the case. From start to finish, it takes approximately 2.5 hours to produce a single-appointment chairside restoration. The technique used in this case offers a fast-paced workflow that is comfortable and practical for the patient and provides a predictable clinical outcome without the need for a temporary restoration.

Association of continuous subcutaneous insulin therapy and diabetic retinopathy in type 1 diabetes: A national cohort study.

AIM: This study aimed to investigate the short-and long-term effect on diabetic retinopathy (DR) in individuals with type 1 diabetes treated with continuous subcutaneous insulin injections (CSII) compared to those using multiple daily injections (MDI). METHODS: We conducted a register-based matched cohort study utilizing data from the Danish Registry of Diabetic Retinopathy as well as several other national Danish health registers. Our cohort consisted of all individuals with type 1 diabetes who attended the Danish screening program for DR from 2013 to 2022. We included individuals registered with CSII treatment, and compared them to individuals using MDI, matched by age, sex, and DR level. Cox regression analysis was performed to evaluate the outcomes. RESULTS: The study included 674 individuals treated with CSII and 2006 matched MDI users. In our cohort 53.4 % were female and median age was 36 (IQR 27-47). Average follow-up risk-time was 4.8 years. There was no difference in the risk of DR worsening between the CSII group and MDI group (HR 1.05 [95%CI 0.91; 1.22], p = 0.49). However, an increased risk of focal photocoagulation was observed in the CSII group (HR 2.40 [95%CI 1.11; 5.19], p = 0.03). CONCLUSIONS: Our findings indicate that CSII treatment does not confer a significant difference in the overall short- and long-term risk of DR worsening or ocular intervention compared to MDI treatment. These results provide insights into the DR outcomes of CSII treatment in individuals with type 1 diabetes.

Identification of pathways to high-level vancomycin resistance in Clostridioides difficile that incur high fitness costs in key pathogenicity traits.

Clostridioides difficile is an important human pathogen, for which there are very limited treatment options, primarily the glycopeptide antibiotic vancomycin. In recent years, vancomycin resistance has emerged as a serious problem in several gram-positive pathogens, but high-level resistance has yet to be reported for C. difficile, although it is not known if this is due to constraints upon resistance evolution in this species. Here, we show that resistance to vancomycin can evolve rapidly under ramping selection but is accompanied by fitness costs and pleiotropic trade-offs, including sporulation defects that would be expected to severely impact transmission. We identified 2 distinct pathways to resistance, both of which are predicted to result in changes to the muropeptide terminal D-Ala-D-Ala that is the primary target of vancomycin. One of these pathways involves a previously uncharacterised D,D-carboxypeptidase, expression of which is controlled by a dedicated two-component signal transduction system. Our findings suggest that while C. difficile is capable of evolving high-level vancomycin resistance, this outcome may be limited clinically due to pleiotropic effects on key pathogenicity traits. Moreover, our data identify potential mutational routes to resistance that should be considered in genomic surveillance.

Quantifying the Burden of Opioid Use Disorder and Non-fatal Opioid Overdose in American Indian and Alaskan Native Populations Using the Cerner Real-World Data™ Database.

OBJECTIVE: This study evaluated the prevalence and incidence of opioid use disorder (OUD), rates of opioid overdose (OD), and rates of non-fatal (NF) OD in American Indian/Alaskan Native (AI/AN) populations. METHODS: We used de-identified patient data from Oracle Cerner Real-World Data™. Rates were estimated over time, and stratified by sex, age, marital status, insurance, and region. Mann-Kendall trend tests and Theil-Sen slopes assessed changes over time for each group while autoregressive modeling assessed differences between groups. RESULTS: The study identified trends in OUD and OD among 700,225 AI/AN patients aged 12 and above. Between 2012 and 2022, there was a significant upward trend in both OUD and OD rates (p < 0.05) , with OUD diagnosed in 1.75% and OD in 0.38% of the population. The Western region of the US exhibited the highest rates of OUD and OD. The 35-49 age group showed the highest rates of OUD, while the 12-34 age group had the highest rates of OD. Marital status analysis revealed higher rates of OUD and OD among separated, widowed, or single patients. Additionally, individuals with Medicare or Medicaid insurance demonstrated the highest rates of OUD and OD. CONCLUSION: Results show that rates of OUD, OD, and NF OD continue to rise among AI/AN individuals, with some regional and demographic variation. Our study provides foundational estimates of key AI/AN populations bearing greater burdens of opioid-related morbidity that federal, state, and tribal organizations can use to direct and develop targeted resources that can improve the health and well-being of AI/AN communities.

A Qualitative Study of Internal Medicine Subspecialty Fellowship Program Directors' Perspectives on Short-Term Hospitalist Employment Prior to Fellowship.

Background Some internal medicine (IM) residents pursuing subspecialty training choose short-term hospitalist employment prior to fellowship, or "pre-fellowship hospitalist years." Residency and fellowship program directors (PDs) advise residents on this decision, but PD experience with fellows pursuing pre-fellowship hospitalist years and the impact on fellowship applications is unknown. Objective We aimed to explore perceptions of fellowship PDs regarding experience with fellows who pursued pre-fellowship hospitalist years, including perceived effects on how such years affect fellowship application candidacy. Methods A purposive sample of 20 fellowship PDs in the most highly competitive and commonly selected IM fellowships (cardiology, pulmonology/critical care medicine, hematology/oncology, gastroenterology) from 5 academic institutions were approached for participation in fall 2021. Interviews included semi-structured questions about pre-fellowship hospitalist employment. Utilizing rapid qualitative analysis, interview transcripts were summarized and reviewed to identify themes and subthemes describing fellowship PDs' perspectives of pre-fellowship hospitalist years. Results Sixteen fellowship PDs (80%) participated. PDs identified 4 major themes as important for trainees considering pre-fellowship hospitalist years: (1) Explain the "Why"-why the year was pursued; (2) Characteristics of the Hospitalist Position-what type of employment; (3) The Challenges-potential concerns faced with pre-fellowship hospitalist years; and (4) Describe the "What"-the experience's contribution to resident professional development. Conclusions Fellowship PDs in 4 competitive IM subspecialities placed a strong emphasis on explaining a clear, logical reason for seeking short-term hospitalist employment prior to fellowship, describing how it fits into the overall career trajectory, and selecting activities that demonstrate continued commitment to the subspecialty.

Muscle-driven predictive physics simulations of quadrupedal locomotion in the horse.

Musculoskeletal simulations can provide insights into the underlying mechanisms that govern animal locomotion. In this study, we describe the development of a new musculoskeletal model of the horse, and to our knowledge present the first fully muscle-driven, predictive simulations of equine locomotion. Our goal was to simulate a model that captures only the gross musculoskeletal structure of a horse, without specialized morphological features. We mostly present simulations acquired using feedforward control, without state feedback ("top-down control"). Without using kinematics or motion capture data as an input, we have simulated a variety of gaits that are commonly used by horses (walk, pace, trot, tölt, and collected gallop). We also found a selection of gaits that are not normally seen in horses (half bound, extended gallop, ambling). Due to the clinical relevance of the trot, we performed a tracking simulation that included empirical joint angle deviations in the cost function. To further demonstrate the flexibility of our model, we also present a simulation acquired using spinal feedback control, where muscle control signals are wholly determined by gait kinematics. Despite simplifications to the musculature, simulated footfalls and ground reaction forces followed empirical patterns. In the tracking simulation, kinematics improved with respect to the fully predictive simulations, and muscle activations showed a reasonable correspondence to electromyographic signals, although we did not predict any anticipatory firing of muscles. When sequentially increasing the target speed, our simulations spontaneously predicted walk-to-run transitions at the empirically determined speed. However, predicted stride lengths were too short over nearly the entire speed range unless explicitly prescribed in the controller, and we also did not recover spontaneous transitions to asymmetric gaits such as galloping. Taken together, our model performed adequately when simulating individual gaits, but our simulation workflow was not able to capture all aspects of gait selection. We point out certain aspects of our workflow that may have caused this, including anatomical simplifications and the use of massless Hill-type actuators. Our model is an extensible, generalized horse model, with considerable scope for adding anatomical complexity. This project is intended as a starting point for continual development of the model and code, which we make available in extensible open-source formats.

Thermodynamic profiles for cotranslational trigger factor substrate recognition.

Molecular chaperones are central to the maintenance of proteostasis in living cells. A key member of this protein family is trigger factor (TF), which acts throughout the protein life cycle and has a ubiquitous role as the first chaperone encountered by proteins during synthesis. However, our understanding of how TF achieves favorable interactions with such a diverse substrate base remains limited. Here, we use microfluidics to reveal the thermodynamic determinants of this process. We find that TF binding to empty 70S ribosomes is enthalpy-driven, with micromolar affinity, while nanomolar affinity is achieved through a favorable entropic contribution for both intrinsically disordered and folding-competent nascent chains. These findings suggest a general mechanism for cotranslational TF function, which relies on occupation of the exposed TF-substrate binding groove rather than specific complementarity between chaperone and nascent chain. These insights add to our wider understanding of how proteins can achieve broad substrate specificity.