Second-Coordination-Sphere Effects Reveal Electronic Structure Differences between the Mitochondrial Amidoxime Reducing Component and Sulfite Oxidase.

A combination of X-ray absorption and low-temperature electronic absorption spectroscopies has been used to probe the geometric and electronic structures of the human mitochondrial amidoxime reducing component enzyme (hmARC1) in the oxidized Mo(VI) and reduced Mo(IV) forms. Extended X-ray absorption fine structure analysis revealed that oxidized enzyme possesses a 5-coordinate [MoO2(SCys)(PDT)]- (PDT = pyranopterin dithiolene) active site with a cysteine coordinated to Mo. A 5-coordinate geometry is retained in the reduced state, with the equatorial oxo being protonated. Low-temperature electronic absorption spectroscopy of hmARC1 reveals a spectrum for the oxidized enzyme that is significantly different from what has been reported for sulfite oxidase family enzymes. Time-dependent density functional theory computations on oxidized and reduced hmARC1, and a small molecule analogue for hmARC1ox, have been used to assist us in making detailed band assignments and developing a greater understanding of enzyme electronic structure contributions to reactivity. Our understanding of the hmARCred HOMO and the LUMO of the benzamidoxime substrate reveal a potential π-bonding interaction between these redox orbitals, with two-electron occupation of the substrate LUMO along the reaction coordinate activating the O-N bond for cleavage and promoting oxygen atom transfer to the Mo site.

Increased kidney stone risk following total pancreatectomy with islet autotransplantation.

BACKGROUND/OBJECTIVES: Chronic pancreatitis (CP) is associated with increased risk of calcium-oxalate kidney stones, likely due to enteric hyperoxaluria. However, the risk of kidney stones for patients with CP after total pancreatectomy with islet autotransplantation (TPIAT) is unknown. We aimed to evaluate kidney stone risk in patients with CP after TPIAT. METHODS: A retrospective analysis of 629 patients who underwent TPIAT was conducted to identify patients who developed kidney stones post-TPIAT. Kaplan-Meier analysis estimated time to first event. An Anderson-Gill proportional-hazards analysis of all kidney stone events described key clinical associations. RESULTS: Mean age at TPIAT was 33 years (SD 15.3, range 3-69); 69.8 % (n = 439) were female. The estimated chance of any kidney stone episodes by 5 years post-TPIAT was 12.8 % (95 % CI: 8.8-16.6 %); by 10 years, 23.2 % (CI: 17.5-28.6 %); by 15 years, 29.4 % (CI: 21.8-36.2 %). Significant associations with kidney stones post-TPIAT included older age (HR 1.25 per 10 years), smoking history (HR 1.72), mild chronic kidney disease (HR 1.96), renal cysts (HR 3.67), pre-TPIAT kidney stones (HR 4.06), family history of kidney stones (HR 4.10), and Roux-en-Y reconstruction (HR 2.68). Of the 77 patients who developed kidney stones, 34 (44.1 %) had recurrent episodes. Of 143 total kidney stone events, 35 (24.5 %) required stone removal, 79 (55.2 %) resolved spontaneously, and 29 (20.3 %) were missing this data. CONCLUSIONS: Patients with CP post-TPIAT commonly have kidney stones: nearly 3 in 10 have ≥1 kidney stone episodes within 15 years. Clinicians should be aware of this risk and counsel patients on prevention.

Treatment of skin lesions related to pseudoxanthoma elasticum in plastic surgery.

BACKGROUND: Pseudoxanthoma elasticum (PXE) is a hereditary disorder of connective tissue characterized by progressive calcification and fragmentation of elastic fibers, which primarily affects the skin, retinal and arterial walls. Skin damage takes the form of yellow papules that can merge to create a cutaneous fold. This is accompanied by an excess of skin on the different sides of the neck and in the largest folds. These changes to the skin have a significant aesthetic, functional and psychological impact, especially among women. PATIENTS AND METHODS: We evaluated the treatment options in all patients with PXE of our University-Hospital. This group contains people who have been hospitalized for the assessment of their disease and applicants for surgical correction. The goal of the surgery was not the total removal of the lesions but instead a decrease in their size and a tightening of the skin. RESULTS: In total, 250 patients were seen between 2007 and 2022. Surgical treatment was advised for 29 women and 1 man. The main interventions were based on standard techniques such as cervico-facial facelifts, brachioplasties and cruroplasties. The results obtained during postoperative follow-up consultations were rated satisfactory to very good, both aesthetically and functionally. There were no postoperative complications recorded: neither bruising nor scarring issues. Patients with PXE heal as normal. CONCLUSION: Surgical treatment for excess skin observed during PXE is poorly described. Yet, these excesses can be removed when they become troublesome by making use of and adapting the traditional methods of plastic surgery for tightening of the skin.

Surgical Necrotizing Enterocolitis and Spontaneous Intestinal Perforation Lead to Severe Growth Failure in Infants.

OBJECTIVE: We aimed to determine the incidence of growth failure in infants with necrotizing enterocolitis (NEC) or spontaneous intestinal perforation (SIP) and whether initial laparotomy versus peritoneal drainage (PD) impacted the likelihood of growth failure. SUMMARY BACKGROUND DATA: Infants with surgical NEC and SIP have high mortality, and most have neurodevelopmental impairment and poor growth. Existing literature on growth outcomes for these infants is limited. METHODS: This is a preplanned secondary study of the Necrotizing Enterocolitis Surgery Trial dataset. The primary outcome was growth failure (Z-score for weight <-2.0) at 18 to 22 months. We used logistic regression, including diagnosis and treatment, as covariates. Secondary outcomes were analyzed using the Fisher exact or Pearson χ2 test for categorical variables and the Wilcoxon rank sum test or one-way ANOVA for continuous variables. RESULTS: Among 217 survivors, 207 infants (95%) had primary outcome data. Growth failure at 18 to 22 months occurred in 24/50 (48%) of NEC infants versus 65/157 (42%) SIP (P=0.4). The mean weight-for-age Z-score at 18 to 22 months in NEC infants was -2.05±0.99 versus -1.84±1.09 SIP (P=0.2), and the predicted mean weight-for-age Z-score SIP (Beta -0.27; 95% CI: -0.53, -0.01; P=0.041). Median declines in weight-for-age Z-score between birth and 18 to 22 months were significant in all infants but most severe (>2) in NEC infants (P=0.2). CONCLUSIONS: This first ever prospective study of growth outcomes in infants with surgical NEC or SIP demonstrates that growth failure is very common, especially in infants with NEC, and persists at 18-22 months.

Lipoprotein metabolism mediates hematopoietic stem cell responses under acute anemic conditions.

Hematopoietic stem cells (HSCs) react to various stress conditions. However, it is unclear whether and how HSCs respond to severe anemia. Here, we demonstrate that upon induction of acute anemia, HSCs rapidly proliferate and enhance their erythroid differentiation potential. In severe anemia, lipoprotein profiles largely change and the concentration of ApoE increases. In HSCs, transcription levels of lipid metabolism-related genes, such as very low-density lipoprotein receptor (Vldlr), are upregulated. Stimulation of HSCs with ApoE enhances their erythroid potential, whereas HSCs in Apoe knockout mice do not respond to anemia induction. VldlrhighHSCs show higher erythroid potential, which is enhanced after acute anemia induction. VldlrhighHSCs are epigenetically distinct because of their low chromatin accessibility, and more chromatin regions are closed upon acute anemia induction. Chromatin regions closed upon acute anemia induction are mainly binding sites of Erg. Inhibition of Erg enhanced the erythroid differentiation potential of HSCs. Our findings indicate that lipoprotein metabolism plays an important role in HSC regulation under severe anemic conditions.

Bone marrow edema-like signal after cartilage repair does not affect outcomes in a five-year follow-up.

OBJECTIVES: Bone marrow edema-like signal (BMELS) after cartilage repair is common, but its clinical significance remains uncertain. This study aimed to investigate the clinical and structural significance of BMELS following microfracturing (MFX) and matrix-induced autologous chondrocyte implantation (MACI). METHODS: In this multicenter study, MRI examinations were performed over a period of 5 years after cartilage repair surgery (MFX n = 17; MACI n = 28) in 45 patients. Morphological assessments, including the MOCART 2.0 (magnetic resonance observation of cartilage repair tissue), quantitative imaging biomarkers (QIB) with T2 mapping of the repair tissue, and, specifically, assessment of the presence and size of BMELS, were conducted along with patient-reported outcome measures, such as the Knee injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC). BMELS structural and clinical assessments were obtained after 3 months, 12 months, and 60 months. Statistical analysis included the Mann-Whitney U-test, Wilcoxon rank test, Shapiro-Wilk test, and simulation-based power analysis. RESULTS: BMELS were a common finding 60 months after cartilage repair. The size of BMELS differed significantly only between MACI and MFX patients after 3 months, with larger BMELS occurring in the MFX group. There were no significant differences in patients with or without BMELS regarding the T2 ratio of the treated area, the MOCART 2.0, or clinical scores. CONCLUSION: BMELS frequently appeared after cartilage repair procedures. We could show that the postoperative size and change in the size of BMELS after MACI and MFX did not affect clinical scores, morphological MRI results, or biochemical properties of the treated area after 60 months. KEY POINTS: Question What is the clinical significance of bone marrow edema-like signal (BMELS) appearance after matrix-induced autologous chondrocyte implantation (MACI) or microfracture (MFX)? Finding There were no significant differences in patients with or without BMELS regarding the T2 ratio of the treated area, the MOCART 2.0, or clinical scores. Clinical relevance BMELS frequently appeared after cartilage repair, the appearance or the size dynamic after MACI and MFX did not affect clinical scores, morphological MRI results, or biochemical properties after 60 months.

Novel COL5A1 variants and associated disease phenotypes in dogs with classical Ehlers-Danlos syndrome.

BACKGROUND: Human patients with Ehlers-Danlos syndrome (EDS) are categorized into subtypes based on causative genetic variants and phenotypes. The classical form of EDS, primarily caused by variants in COL5A1 or COL5A2, is a very common subtype in people but is poorly characterized in dogs. OBJECTIVE: Describe likely causal COL5A1 variants in dogs with classical EDS, summarize clinical histories, discuss potential disease mechanisms, and draw conclusions about disease prognosis. ANIMALS: Seven client-owned dogs that exhibited clinical signs of classical EDS. METHODS: Clinical information was recorded from medical records and communication with attending veterinarians and dog owners. To identify potential causal gene sequence variants whole-genome sequence analyses (n = 6) or Sanger sequencing (n = 1) were performed on DNA isolated from the probands. Pathological abnormalities in skin biopsy samples were assessed using histology and electron microscopy in 3 dogs. RESULTS: Six distinct heterozygous COL5A1 sequence variants were identified. The most common clinical signs included fragile skin (n = 7), hyperextensible skin (n = 7), joint hypermobility (n = 6), and atrophic scars (n = 5). The median age at last follow-up or death was 12 years (range, 6.5-14 years). Ultrastructural abnormalities in dermal collagen differed among dogs with different COL5A1 variants. CONCLUSION AND CLINICAL IMPORTANCE: We describe the genotypic and phenotypic spectrum of the classical subtype of EDS by identifying 6 novel COL5A1 variants in conjunction with detailed clinical histories that included long-term follow-up information in 7 dogs.

Beyond Clinical Examination: Utilizing MRI Surveillance to Detect Recurrence of Soft Tissue Sarcomas and Differentiate from Posttherapeutic Changes.

BACKGROUND: Early detection of soft tissue sarcoma (STS) recurrence is essential; however, the role and timeline of Magnetic resonance imaging (MRI) surveillance are still under debate. The aim of this study was to determine whether local recurrence (LR) could be identified via clinical examination alone and to assess the MRI morphology of primary STS and LR. METHODS: This retrospective study included all patients with STS recurrence after surveillance for at least five years from the tumor database of the Medical University of Vienna from 2000 until December 2023. The characteristics of primary STS and LR and the time interval to recurrence and clinical detectability were assessed. The MRIs of LR and posttherapeutic changes (PTC) were compared with the initial MRIs. RESULTS: A total of 57 patients (60% male; mean age 58.5 ± 18.0 years) with STS and histologically confirmed LR were included. The mean time interval to LR was 2.3 ± 1.8 years (range 108 to 3037 days). The clinically detectable recurrences were significantly larger than the inapparent ones (71.9 cm3 vs. 7.0 cm3; p < 0.01). The MRI morphology of all LRs (26/26) closely resembled the initial STS. For comparison, nine patients were included with clinically suspected LRs, which were histologically proven to be PTC. None of these resembled the primary STS. CONCLUSION: Based on clinical symptoms alone, especially small and early recurrences can be missed, which supports the importance of MRI surveillance.

Alleviation of cadmium toxicity in soybean (Glycine max L.): Up-regulating antioxidant capacity and enzyme gene expressions and down-regulating cadmium uptake by organic or inorganic selenium.

Although much interest has been focused on the role of selenium (Se) in plant nutrition over the last 20 years, the influences of organic selenium (selenomethionine; Se-Met) and inorganic selenium (potassium selenite; Se-K) on the growth and physiological characters of cadmium (Cd)-stressed Glycine max L.) seedlings have not yet been studied. In this study, the impacts of Se-Met or Se-K on the growth, water physiological parameters (gaseous exchange and leaf water content), photosynthetic and antioxidant capacities, and hormonal balance of G. max seedlings grown under 1.0 mM Cd stress were studied. The results showed that 30 µM Se-K up-regulates water physiological parameters, photosynthetic indices, antioxidant systems, enzymatic gene expression, total antioxidant activity (TAA), and hormonal balance. In addition, it down-regulates levels of reactive oxygen species (ROS; superoxide free radicals and hydrogen peroxide), oxidative damage (malondialdehyde content as an indicator of lipid peroxidation and electrolyte leakage), Cd translocation factor, and Cd content of Cd-stressed G. max seedlings. These positive findings were in favor of seedling growth and development under Cd stress. However, 50 µM Se-Met was more efficient than 30 µM Se-K in promoting the above-mentioned parameters of Cd-stressed G. max seedlings. From the current results, we conclude Se-Met could represent a promising strategy to contribute to the development and sustainability of crop production on soils contaminated with Cd at a concentration of up to 1.0 mM. However, further work is warranted to better understand the precise mechanisms of Se-Met action under Cd stress conditions.

The mevalonate pathway contributes to breast primary tumorigenesis and lung metastasis.

The mevalonate pathway plays an important role in breast cancer and other tumor types. However, many issues remain obscure as yet regarding its mechanism of regulation and action. In the present study, we report that the expression of mevalonate pathway enzymes is mediated by the RHO guanosine nucleotide exchange factors VAV2 and VAV3 in a RAC1- and sterol regulatory element-binding factor (SREBF)-dependent manner in breast cancer cells. Furthermore, in vivo tumorigenesis experiments indicated that the two most upstream steps of this metabolic pathway [3-hydroxy-3-methylglutaryl-coenzyme A synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR)] are important for primary tumorigenesis, angiogenesis, and cell survival in breast cancer cells. HMGCR, but not HMGCS1, is also important for the extravasation and subsequent fitness of breast cancer cells in the lung parenchyma. Genome-wide expression analyses revealed that HMGCR influences the expression of gene signatures linked to proliferation, metabolism, and immune responses. The HMGCR-regulated gene signature predicts long-term tumor recurrence but not metastasis in cohorts of nonsegregated and chemotherapy-resistant breast cancer patients. These results reveal a hitherto unknown, VAV-catalysis-dependent mechanism involved in the regulation of the mevalonate pathway in breast cancer cells. They also identify specific mevalonate-pathway-dependent processes that contribute to the malignant features of breast cancer cells.

Probing the killing potency of tumor-infiltrating lymphocytes on microarrayed colorectal cancer tumoroids.

Immunotherapy has emerged as a new standard of care for certain cancer patients with specific cellular and molecular makeups. However, there is still an unmet need for ex vivo models able to readily assess the effectiveness of immunotherapeutic treatments in a high-throughput and patient-specific manner. To address this issue, we have developed a microarrayed system of patient-derived tumoroids with recreated immune microenvironments that are optimized for the high-content evaluation of tumor-infiltrating lymphocyte functionality. Here we show that this system offers unprecedented opportunities to evaluate tumor immunogenicity, characterize the response to immunomodulators, and explore novel approaches for personalized immuno-oncology.

Hypoaldosteronism due to a novel SEC61A1 variant successfully treated with fludrocortisone.

Background: Genetic variants in SEC61A1 are associated with autosomal dominant tubulointerstitial kidney disease. SEC61A1 is a translocon in the endoplasmic reticulum membrane and variants affect biosynthesis of renin and uromodulin. Methods: A patient is described that presented at 1 year of age with failure-to-thrive, kidney failure (glomerular filtration rate, GFR, 18 ml/min/1.73m2), hyperkalemia and acidosis. Genetic evaluation was performed by whole genome sequencing. Results: The patient has a novel de novo heterozygous SEC61A1 variant, Phe458Val. Plasma renin was low or normal, aldosterone was low or undetectable and uromodulin was low. Kidney biopsy at 2 years exhibited subtle changes suggestive of tubular dysgenesis without tubulocystic or glomerulocystic lesions and with renin staining of the juxtaglomerular cells. The patient experienced extreme fatigue due to severe hypotension attributed to hypoaldosteronism and at 8 years of age fludrocortisone treatment was initiated with marked improvement in her well-being. Blood pressure and potassium normalized. Biopsy at 9 years showed extensive glomerulosclerosis and mild tubulointerstitial fibrosis, as well as tubular mitochondrial abnormalities, without specific diagnostic changes. Her GFR improved to 54 ml/min/1.73m2. Conclusions: As the renin-angiotensin system promotes aldosterone release, and the patient had repeatedly undetectable aldosterone levels, the SEC61A1 variant presumably contributed to severe hypotension. Treatment with a mineralocorticoid had a beneficial effect and corrected the electrolyte and acid-base disorder. We suggest that the increased blood pressure hemodynamically improved the patient's kidney function.

Evaluation of Clinical Performance of Ponto Implantation Using a Minimally Invasive Surgical Technique-A Prospective Multicenter Study.

OBJECTIVE: To investigate the clinical outcomes of bone-anchored hearing implant surgery using the MONO procedure. STUDY DESIGN: Multicenter, multinational, single-arm, prospective trial with a 12-month follow-up. SETTING: Seven European university hospitals from the United Kingdom, Sweden, Denmark, and The Netherlands. PATIENTS: Fifty-one adult patients requiring surgical intervention for bone conduction hearing. INTERVENTION: Bone-anchored hearing implant surgery using the MONO procedure. MAIN OUTCOME MEASURES: The primary endpoint assessed implant usability 3 months after surgery. Implant status, soft tissue reactions, pain and numbness, postoperative events, and sound processor usage were assessed at all follow-up visits. Hearing-related quality of life was evaluated using the Glasgow Benefit Inventory (GBI). RESULTS: At 3 months, 94.2% of the implant/abutment complexes provided reliable anchorage for sound processor usage. No severe intraoperative complications occurred. Sixty-nine percent of surgeries were performed under local anesthesia, with surgery lasting 10 minutes on average. Four implants were lost due to trauma (n = 2), spontaneous loss of osseointegration (n = 1), or incomplete insertion (n = 1). Adverse soft tissue reactions occurred in 2.6% of visits, with a maximum Holgers grade of 3 (n = 1) and grade 2 (n = 5) across patients. Hearing-related quality of life at 3 months improved in 96% of patients. CONCLUSION: The MONO procedure provides a safe and efficient surgical technique for inserting bone-anchored hearing implants with few and minor intra- and postoperative complications.

Self-Assembled Fibroblast Growth Factor Nanoparticles as a Therapeutic for Oxidant-Induced Neuronal and Skin Cell Injury.

Traumatic brain injury (TBI) and spinal cord injury (SCI) are neurological conditions that result from immediate mechanical injury, as well as delayed injury caused by local inflammation. Furthermore, TBI and SCI often lead to secondary complications, including pressure wounds of the skin, which can heal slowly and are prone to infection. Pressure wounds are localized areas of damaged tissue caused by prolonged pressure on the skin due to immobility and loss of neurological sensation. With the aim to ameliorate these symptoms, we investigated whether fibroblast growth factors 2 (FGF-2) could contribute to recovery. FGF-2 plays a significant role in both neurogenesis and skin wound healing. We developed a recombinant fusion protein containing FGF-2 linked to elastin-like polypeptides (FGF-ELP) that spontaneously self-assembles into nanoparticles at around 33 °C. The nanoparticle's size was ranging between 220 and 250 nm in diameter at 2 µM. We tested this construct for its ability to address neuronal and skin cell injuries. Hydrogen peroxide was used to induce oxidant-mediated injury on cultured neuronal cells to mimic the impact of reactive oxidants released during the inflammatory response in vivo. We found that FGF-ELP nanoparticles protected against hydrogen peroxide-mediated injury and promoted neurite outgrowth. In the skin cell models, cells were depleted from serum to mimic the reduced levels of nutrients and growth factors in chronic skin wounds. FGF-ELP increased the proliferation and migration of human keratinocytes, fibroblasts, and endothelial cells. FGF-ELP is, therefore, a potentially useful agent to provide both neuroprotection and promotion of cellular processes involved in skin wound healing.

[Assessment tool's validation study for a simulation-based skin suturing skill]. / Étude de validation d'une grille d'évaluation d'un exercice de suture cutanée en simulation.

CONTEXT: Health simulation is a recognized educational method for teaching and validating surgical procedural skills. The latter requires the development of adapted assessment tools, reaching different validity criteria. The aim of this study was to validate a multimodal assessment tool for a complex skin suturing exercise, combining a manual knot, an intradermal linear suturing and a needle holder tied knot. METHODOLOGY: The suturing exercise was realized on a synthetic skin model by voluntary participants after having obtained their written consent, including 9 postgraduate medical students, 40 surgical residents of different levels of experience, and a group of 9 senior surgeons. The multimodal assessment tool (MAT) combined a checklist, a speed score and a global rating scale. Each exercise was scored by two evaluators. Medical students' performances were filmed anonymously so that they could be scored iteratively. Content validity was tested through a satisfaction questionnaire randomly completed by participants. RESULTS: The MAT was considered relevant or very relevant by 98% of the participants, with a better appreciation for the checklist than for the global rating scale. Internal consistency was strong with a Cronbach α coefficient at 0.78, and a good correlation between the results of the checklist and the global rating scale (r=0.79, P<0.0001). The MAT showed continuous improvement in mean scores from 34.4±3.6 for novices to 47.4±2.5/50 points for experts, passing through three intermediate levels groups, and allowed for significant discrimination between groups. The MAT was reliable, with a coefficient of correlation set at 0.88 for intra-observer reliability, and 0.72 for inter-observer reliability. On sub score analysis, the global rating scale and the speed score better discriminated between groups than the checklist, the latter moreover showing slightly lower reliability than the global rating scale. CONCLUSION: Despite its banality in any surgeon's practice and the fact that it is taught from the 2nd cycle of medical studies, suturing and its technical components have rarely been the subject of publications dedicated to the validation of specific assessment tools. Hence, this work on the MAT and its sub scores made it possible to validate them on many validity and reliability criteria. They can therefore be proposed to surgical teachers for evaluating a complex suturing exercise, with a checklist that is easier to use even for novices and a global rating scale showing better discrimination capacity.

Artificial intelligence coronary computed tomography, coronary computed tomography angiography using fractional flow reserve, and physician visual interpretation in the per-vessel prediction of abnormal invasive adenosine fractional flow reserve.

Aims: A comparison of diagnostic performance comparing AI-QCTISCHEMIA, coronary computed tomography angiography using fractional flow reserve (CT-FFR), and physician visual interpretation on the prediction of invasive adenosine FFR have not been evaluated. Furthermore, the coronary plaque characteristics impacting these tests have not been assessed. Methods and results: In a single centre, 43-month retrospective review of 442 patients referred for coronary computed tomography angiography and CT-FFR, 44 patients with CT-FFR had 54 vessels assessed using intracoronary adenosine FFR within 60 days. A comparison of the diagnostic performance among these three techniques for the prediction of FFR ≤ 0.80 was reported. The mean age of the study population was 65 years, 76.9% were male, and the median coronary artery calcium was 654. When analysing the per-vessel ischaemia prediction, AI-QCTISCHEMIA had greater specificity, positive predictive value (PPV), diagnostic accuracy, and area under the curve (AUC) vs. CT-FFR and physician visual interpretation CAD-RADS. The AUC for AI-QCTISCHEMIA was 0.91 vs. 0.76 for CT-FFR and 0.62 for CAD-RADS ≥ 3. Plaque characteristics that were different in false positive vs. true positive cases for AI-QCTISCHEMIA were max stenosis diameter % (54% vs. 67%, P < 0.01); for CT-FFR were maximum stenosis diameter % (40% vs. 65%, P < 0.001), total non-calcified plaque (9% vs. 13%, P < 0.01); and for physician visual interpretation CAD-RADS ≥ 3 were total non-calcified plaque (8% vs. 12%, P < 0.01), lumen volume (681 vs. 510 mm3, P = 0.02), maximum stenosis diameter % (40% vs. 62%, P < 0.001), total plaque (19% vs. 33%, P = 0.002), and total calcified plaque (11% vs. 22%, P = 0.003). Conclusion: Regarding per-vessel prediction of FFR ≤ 0.8, AI-QCTISCHEMIA revealed greater specificity, PPV, accuracy, and AUC vs. CT-FFR and physician visual interpretation CAD-RADS ≥ 3.

Active Site Characterization of a Campylobacter jejuni Nitrate Reductase Variant Provides Insight into the Enzyme Mechanism.

Mo K-edge X-ray absorption spectroscopy (XAS) is used to probe the structure of wild-type Campylobacter jejuni nitrate reductase NapA and the C176A variant. The results of extended X-ray absorption fine structure (EXAFS) experiments on wt NapA support an oxidized Mo(VI) hexacoordinate active site coordinated by a single terminal oxo donor, four sulfur atoms from two separate pyranopterin dithiolene ligands, and an additional S atom from a conserved cysteine amino acid residue. We found no evidence of a terminal sulfido ligand in wt NapA. EXAFS analysis shows the C176A active site to be a 6-coordinate structure, and this is supported by EPR studies on C176A and small molecule analogs of Mo(V) enzyme forms. The SCys is replaced by a hydroxide or water ligand in C176A, and we find no evidence of a coordinated sulfhydryl (SH) ligand. Kinetic studies show that this variant has completely lost its catalytic activity toward nitrate. Taken together, the results support a critical role for the conserved C176 in catalysis and an oxygen atom transfer mechanism for the catalytic reduction of nitrate to nitrite that does not employ a terminal sulfido ligand in the catalytic cycle.

Assembly of respiratory syncytial virus matrix protein lattice and its coordination with fusion glycoprotein trimers.

Respiratory syncytial virus (RSV) is an enveloped, filamentous, negative-strand RNA virus that causes significant respiratory illness worldwide. RSV vaccines are available, however there is still significant need for research to support the development of vaccines and therapeutics against RSV and related Mononegavirales viruses. Individual virions vary in size, with an average diameter of ~130 nm and ranging from ~500 nm to over 10 µm in length. Though the general arrangement of structural proteins in virions is known, we use cryo-electron tomography and sub-tomogram averaging to determine the molecular organization of RSV structural proteins. We show that the peripheral membrane-associated RSV matrix (M) protein is arranged in a packed helical-like lattice of M-dimers. We report that RSV F glycoprotein is frequently observed as pairs of trimers oriented in an anti-parallel conformation to support potential interactions between trimers. Our sub-tomogram averages indicate the positioning of F-trimer pairs is correlated with the underlying M lattice. These results provide insight into RSV virion organization and may aid in the development of RSV vaccines and anti-viral targets.

Patient-derived mini-colons enable long-term modeling of tumor-microenvironment complexity.

Existing organoid models fall short of fully capturing the complexity of cancer because they lack sufficient multicellular diversity, tissue-level organization, biological durability and experimental flexibility. Thus, many multifactorial cancer processes, especially those involving the tumor microenvironment, are difficult to study ex vivo. To overcome these limitations, we herein implemented tissue-engineering and microfabrication technologies to develop topobiologically complex, patient-specific cancer avatars. Focusing on colorectal cancer, we generated miniature tissues consisting of long-lived gut-shaped human colon epithelia ('mini-colons') that stably integrate cancer cells and their native tumor microenvironment in a format optimized for real-time, high-resolution evaluation of cellular dynamics. We demonstrate the potential of this system through several applications: a comprehensive evaluation of drug effectivity, toxicity and resistance in anticancer therapies; the discovery of a mechanism triggered by cancer-associated fibroblasts that drives cancer invasion; and the identification of immunomodulatory interactions among different components of the tumor microenvironment. Similar approaches should be feasible for diverse tumor types.

Thymic epithelial organoids mediate T-cell development.

Although the advent of organoids has opened unprecedented perspectives for basic and translational research, immune system-related organoids remain largely underdeveloped. Here, we established organoids from the thymus, the lymphoid organ responsible for T-cell development. We identified conditions enabling mouse thymic epithelial progenitor cell proliferation and development into organoids with diverse cell populations and transcriptional profiles resembling in vivo thymic epithelial cells (TECs) more closely than traditional TEC cultures. In contrast to these two-dimensional cultures, thymic epithelial organoids maintained thymus functionality in vitro and mediated physiological T-cell development upon reaggregation with T-cell progenitors. The reaggregates showed in vivo-like epithelial diversity and the ability to attract T-cell progenitors. Thymic epithelial organoids are the first organoids originating from the stromal compartment of a lymphoid organ. They provide new opportunities to study TEC biology and T-cell development in vitro, paving the way for future thymic regeneration strategies in ageing or acute injuries.