Mouse mucosal-associated invariant T cell receptor recognition of MR1 presenting the vitamin B metabolite, 5-(2-oxopropylideneamino)-6-d-ribitylaminouracil.

Mucosal-associated invariant T (MAIT) cells can elicit immune responses against riboflavin-based antigens presented by the evolutionary conserved MHC class I related protein, MR1. While we have an understanding of the structural basis of human MAIT cell receptor (TCR) recognition of human MR1 presenting a variety of ligands, how the semi-invariant mouse MAIT TCR binds mouse MR1-ligand remains unknown. Here, we determine the crystal structures of 2 mouse TRAV1-TRBV13-2+ MAIT TCR-MR1-5-OP-RU ternary complexes, whose TCRs differ only in the composition of their CDR3ß loops. These mouse MAIT TCRs mediate high affinity interactions with mouse MR1-5-OP-RU and cross-recognize human MR1-5-OP-RU. Similarly, a human MAIT TCR could bind mouse MR1-5-OP-RU with high affinity. This cross-species recognition indicates the evolutionary conserved nature of this MAIT TCR-MR1 axis. Comparing crystal structures of the mouse versus human MAIT TCR-MR1-5-OP-RU complexes provides structural insight into the conserved nature of this MAIT TCR-MR1 interaction and conserved specificity for the microbial antigens, whereby key germline-encoded interactions required for MAIT activation are maintained. This is an important consideration for the development of MAIT cell-based therapeutics that will rely on preclinical mouse models of disease.

Trauma bypass performed by vascular surgeons demonstrate excellent long-term outcomes and limb preservation.

OBJECTIVE: Long-term outcomes in civilian trauma patients requiring upper or lower extremity revascularization is poorly studied secondary to limitations of certain large databases and the nature of the patients in this specific vascular subset. This study reports on the experience and outcomes of a Level 1 trauma center that serves both an urban and a large rural population over a 20-year period to identify bypass outcomes and surveillance protocols. METHODS: Database of a single vascular group at an academic center was queried for trauma patients requiring upper or lower extremity revascularization between January 1, 2002, and June 30, 2022. Patient demographics, indications, operative details, operative mortality, 30-day nonoperative morbidity, revisions, subsequent major amputations, and follow-up data were analyzed. RESULTS: A total of 223 revascularizations were performed, 161 (72%) lower and 62 (28%) upper extremities. One hundred sixty-seven patients (74.9%) were male, with a mean age of 39 years (range, 3-89 years). Comorbidities included hypertension (n = 34; 15.3%), diabetes (n = 6; 2.7%), and tobacco use (n = 40; 17.9%). Mean follow-up time was 23 months (range, 1-234 months), with 90 patients (40.4%) lost to follow-up. Mechanisms included blunt trauma (n = 106; 47.5%), penetrating trauma (n = 83; 37.2%), and operative trauma (n = 34; 15.3%). Bypass conduit was reversed vein (n= 171; 76.7%), prosthetic (n = 34; 15.2%), and orthograde vein (n = 11; 4.9%). Bypass inflow artery was superficial femoral (n = 66; 41.0%), above-knee popliteal (n = 28; 17.4%), and common femoral (n = 20; 12.4%) in the lower extremity, and brachial (n = 41; 66.1%), axillary (n = 10; 16.1%), and radial (n = 6; 9.7%) in the upper extremity. Lower extremity outflow artery was posterior tibial (n = 47; 29.2%), below-knee popliteal (n = 41; 25.5%), superficial femoral (n = 16; 9.9%), dorsalis pedis (n = 10; 6.2%), common femoral (n = 9; 5.6%), and above-knee popliteal (n = 10; 6.2%). Upper extremity outflow artery was brachial (n = 34; 54.8%), radial (n = 13; 21.0%), and ulnar (n = 13; 21.0%). Total operative mortality was nine patients (4.0%), all involving lower extremity revascularization. Thirty-day non-fatal complications included immediate bypass occlusion (n = 11; 4.9%), wound infection (n = 8; 3.6%), graft infection (n = 4; 1.8%), and lymphocele/seroma (n = 7; 3.1%). All major amputations (n = 13; 5.8%) were early and in the lower extremity bypass group. Late revisions in the lower and upper extremity groups were 14 (8.7%) and four (6.4%), respectively. CONCLUSIONS: Revascularization for extremity trauma can be performed with excellent limb salvage rates and has demonstrated long-term durability with low limb loss and bypass revision rates. The poor compliance with long-term surveillance is concerning and may require adjustment in patient retention protocols; however, emergent returns for bypass failure are extremely low in our experience.

Uncomplicated Urinary Tract Infection in Ambulatory Primary Care Pediatrics: Are We Using Antibiotics Appropriately?

OBJECTIVES: Antimicrobial stewardship programs target antimicrobial use within the inpatient care setting. However, most antimicrobials are prescribed at ambulatory sites. We aim to determine the appropriateness of the diagnosis and treatment of uncomplicated urinary tract infection (UTI) in children within the outpatient setting at our institution, and to evaluate the cost of antibiotic treatment in our patient cohort. METHODS: This retrospective study was conducted by reviewing electronic records of patients aged 2 to 18 years diagnosed with uncomplicated UTI and treated with antibiotics in the outpatient setting from January 1, 2016, to April 30, 2016. Appropriate diagnosis was defined as confirmed UTI that included: pyuria (>5 white blood cells per high-power field or positive for leukocyte esterase), a positive urine culture (≥50,000 colony units/mL of a single uropathogen for a catheterized sample or ≥100,000 colony units/mL for a clean catch urine sample), and lower urinary tract symptoms. Treatment was considered appropriate if the patient was prescribed first-line antibiotic for the susceptible isolate (trimethoprim sulfamethoxazole, amoxicillinclavulanate, nitrofurantoin, and cephalexin), and if the appropriate dose was used. RESULTS: We included 178 patients receiving a diagnosis of uncomplicated UTI and treated with antibiotics. Of these, 70% received an inappropriate diagnosis (n = 125). 58% (n= 72) of improperly diagnosed patients had polymicrobial growth in their urine cultures. Antibiotics prescribed mostly in this group were trimethoprim-sulfamethoxazole (53%, n = 66) and cephalexin (22%, n = 27). Only 30% of all included patients received an appropriate diagnosis (n = 53). Of all appropriate diagnosis patients (n = 53), 26% were treated inappropriately (n = 14) with either wide-spectrum antibiotics (n = 8) or with low calculated dose (n = 6). The estimated cost of antibiotic treatment for the inappropriate diagnosis group (n = 125) was $10,755.87. CONCLUSION: Antimicrobial stewardship programs should target the pediatric outpatient setting and antibiograms should be developed. Education of providers about the appropriate diagnosis and treatment of uncomplicated UTI in children is essential for reducing the cost of inappropriate therapy.

A Novel IMP1 Inhibitor, BTYNB, Targets c-Myc and Inhibits Melanoma and Ovarian Cancer Cell Proliferation.

The oncofetal mRNA-binding protein, IMP1 or insulin-like growth factor-2 mRNA-binding protein 2 (IGF2BP1), binds to and stabilizes c-Myc, ß-TrCP1, and other oncogenic mRNAs, leading to increased expression of the proteins encoded by its target mRNAs. IMP1 is frequently overexpressed in cancer and is strongly correlated with a poor prognosis and reduced survival in melanoma, ovarian, breast, colon, and lung cancer. While IMP1 is an attractive anticancer drug target, there are no small molecule inhibitors of IMP1. A fluorescence anisotropy-based assay was used to screen 160,000 small molecules for their ability to inhibit IMP1 binding to fluorescein-labeled c-Myc mRNA. The small molecule, BTYNB, was identified as a potent and selective inhibitor of IMP1 binding to c-Myc mRNA. In cells, BTYNB downregulates several mRNA transcripts regulated by IMP1. BTYNB destabilizes c-Myc mRNA, resulting in downregulation of c-Myc mRNA and protein. BTYNB downregulates ß-TrCP1 mRNA and reduces activation of nuclear transcriptional factors-kappa B (NF-κB). The oncogenic translation regulator, eEF2, emerged as a new IMP1 target mRNA, enabling BTYNB to inhibit tumor cell protein synthesis. BTYNB potently inhibited proliferation of IMP1-containing ovarian cancer and melanoma cells with no effect in IMP1-negative cells. Overexpression of IMP1 reversed BTYNB inhibition of cell proliferation. BTYNB completely blocked anchorage-independent growth of melanoma and ovarian cancer cells in colony formation assays. With its ability to target c-Myc and to inhibit proliferation of difficult-to-target melanomas and ovarian cancer cells, and with its unique mode of action, BTYNB is a promising small molecule for further therapeutic evaluation and mechanistic studies.