Southwestern Medical Center

Friedreich's ataxia (FRDA) is a multisystem, autosomal recessive disease caused by biallelic expansion of GAA repeats in intron 1 of the frataxin gene (FXN). While ∼96% of FRDA patients carry expanded GAA repeats on both FXN alleles, ∼4% are compound heterozygous with expanded GAA repeats on one allele and another mutation on the second allele. We generated induced pluripotent stem cells from blood lymphocytes from a FRDA patient carrying the FXN c.165+5G>C point mutation, which interferes with canonical splicing of intron 1 of the FXN gene. These cells allow for development of therapeutic approaches that target splicing defect in FRDA.

To assess factors associated with retinal detachment (RD) in eyes presenting with endogenous endophthalmitis (EE). Multicenter retrospective study of individuals with an EE diagnosis from seven tertiary care centers. Demographics, medical history, ocular examination findings, microbial cultures (blood or intraocular), and management strategies were assessed relative to subsequent RD occurring within 6 months of EE diagnosis. Of note, this study did not distinguish between intraocular cultures without growth and eyes that were not sampled for an intraocular organism. A total of 201 eyes from 171 patients presented with EE. Of these, 22.4% (45/201) had a subsequent RD. Eyes that experienced a subsequent RD had worse presenting visual acuity ( P = 0.006) and lower intraocular pressure at presentation (RD: 13.7 ± 5.4 mmHg vs. No RD: 15.7 ± 6.5 mmHg, P = 0.04). Compared with other forms of bacteremia, S. aureus bacteremia was associated with increased odds of subsequent RD (OR: 6.10, CI: 1.82-20.41, P = 0.003). Eyes with a subsequent RD did not have significantly greater rates of therapeutic pars plana vitrectomy (RD: 11/48, 22.9% vs. No RD: 36/153, 23.5%). Eyes presenting with visual acuity ≤ light perception or S. aureus bacteremia had a higher risk of subsequent RD and may warrant closer surveillance. Although no therapeutic strategies were associated with reduced odds of subsequent RD, a pars plana vitrectomy was not associated with an increased risk of RD, suggesting that it may aid in eyes with lackluster responses to systemic and intravitreal pharmacotherapy.

Pituitary adenoma (pituitary neuroendocrine tumor) can present a diagnostic pitfall when it involves the sinonasal tract ectopically or by direct extension due to morphologic and immunohistochemical overlap with sinonasal small round blue cell tumors. T-box transcription factor (T-PIT), pituitary-specific transcription factor (PIT-1), and steroidogenic factor 1 (SF-1) have emerged as lineage-specific markers for corticotroph, somatotroph, and gonadotroph-type adenomas, respectively, but have not been extensively tested in sinonasal tumors. We examined T-PIT, PIT-1, and SF-1 expression across sinonasal and skull base tumors to assess their specificity in this differential diagnosis. Staining for T-PIT, PIT-1, and SF-1 was performed on tissue microarrays including 199 sinonasal tumors and 12 nonsinonasal head and neck neuroendocrine carcinomas. Whole tissue sections from 20 adenomas, 2 olfactory carcinomas, and 1 Merkel cell carcinoma of nasal skin also underwent staining for all 3 markers, while 9 other sinonasal or skull base tumors underwent staining for T-PIT and PIT-1 only. All 223 sinonasal tumors and neuroendocrine carcinomas of the head and neck were negative for T-PIT and PIT-1. Only 7 of 214 nonpituitary tumors (3.3%) showed SF-1 expression, including 2 of 43 HPV-positive squamous cell carcinomas, 1 of 75 HPV-negative squamous cell carcinomas, 2 of 8 SMARCB1-deficient sinonasal carcinomas, 1 of 4 salivary neuroendocrine carcinomas, and 1 of 5 NUT carcinomas. All pituitary tumors stained as expected. These findings demonstrate that T-PIT and PIT-1 are highly specific for pituitary origin, while SF-1 shows limited off-target expression in certain high-grade sinonasal tumors with chromatin remodeling (e.g., NUT carcinoma and SMARCB1-deficient carcinoma).

Fat body-specific FASN1 loss leads to fat-depleted but viable Drosophila that complete their developmental lifecycle by rewiring energy metabolism to store glycogen instead of fat FASN1-deficient larvae functionally rely on glycogen synthesis and glycolysis, but not lactate metabolism, and display blunted TCA metabolismMetabolic screening reveals a SREBP-dependent TG:glycogen metabolic switch in response to blockage of DNL fatty acid biosynthesisHistone acetyltransferases (HATs) Nej and Tip60, and acetyl-CoA synthase, are required for the TG:glycogen metabolic switch.

Objective.While FLASH radiotherapy (FLASH-RT) is recognized for normal tissue sparing, its effect in mitigating the toxicity of late-responding organs remains uncertain, limiting clinical adoption. With its clinical importance and steep dose-response, spinal cord is an ideal model for evaluating the FLASH effect on late toxicity. This work introduces a robust image-guided research platform for high-precision irradiation at both conventional (CONV) and ultra-high dose rates (UHDR) to enable FLASH late toxicity studies using a rat spinal cord model.Approach.A modified LINAC was employed to irradiate the C1-T2 rat spinal cord with 18 MeV UHDR and CONV beams. A custom rat immobilization device, a portable x-ray imaging system, and an ion-chamber-based UHDR output monitoring system were integrated to ensure accurate C1-T2 localization and precise dose delivery. A Monte Carlo (MC) dose engine was developed to provide accurate dosimetry and support the interpretation ofin vivoresults. Scintillator measurements at UHDR were performed within the spinal cord to verify MC results and the precision of our platform.Results.We observed submillimeter deviation in C1-T2 localization between 2D x-ray and 3D cone beam computed tomography imaging, as well as between pre- and post-irradiation 2D x-ray assessments. Ion chamber readings showed linear correlation with UHDR output (R2= 1). MC calculations indicated uniform irradiation (<5% non-uniformity) along the central ∼13 mm cord, avoiding dose-volume effects. Our CONV beam exhibited dose distribution close to that of the UHDR beam, with differences < 3%, isolating dose rate as the only variable. Scintillator-measured dose agreed with MC within 4%, with a 100% gamma passing rate (2%/2 mm), confirming both MC accuracy and the platform's high-precision delivery.Significance.We developed the first comprehensive, image-guided preclinical platform for accurate UHDR and CONV irradiation to investigate FLASH-mitigated spinal cord toxicity in rats. This work thus establishes a robust foundation for systematic evaluation of the FLASH effect in late-responding organs and for assessing relevant clinical applicability of FLASH-RT.

To evaluate the validity of the 3-item visual analog scale (3VAS) and 4-item VAS (4VAS) and determine the minimal clinically important difference (MCID) and minimal detectable change (MDC) for each measure using data from 3 phase III randomized clinical trials of guselkumab in psoriatic arthritis (PsA). Pooled data (1405 participants) from the DISCOVER-1, DISCOVER-2, and COSMOS studies were used. 3VAS/4VAS MCID and MDC were estimated using established formulas. Receiver-operating characteristic curve analysis was used to identify 3VAS/4VAS thresholds for low, moderate, and high disease activity. Criterion validity was assessed by correlating 3VAS/4VAS with other PsA measures. Mixed models evaluated the association between changes from baseline in 3VAS/4VAS at week 8 of guselkumab treatment with the total PsA-modified Sharp-van der Heijde (SvdH) score through week 100. 3VAS/4VAS showed moderate-to-strong correlation with all outcome measures assessed, with coefficients ranging from 0.56/0.62 for Health Assessment Questionnaire-Disability Index to 0.92/0.94 for patient global assessment. MCID was 0.9 for both 3VAS (range 0.7-1.3 depending on method used) and 4VAS (0.6-1.3); MDC was 3.1 and 3.0, respectively. 3VAS cutoffs for low, moderate, and high disease activity were 2.1, 3.3, and 4.8, respectively, and 2.1, 3.4, and 5.0 for 4VAS. Change in 4VAS at week 8 of guselkumab treatment significantly associated with change in SvdH score through week 100 (P = 0.04). These analyses support the validity of 3VAS/4VAS as multidimensional measures of PsA disease activity. 4VAS may be preferred owing to its greater face validity and separate measurements of the 2 cardinal aspects of PsA (joint/skin disease) and pain.

Stimulator of interferon genes (STING) is an essential adaptor in the cytosolic DNA-sensing innate immune pathway1. STING is activated by cyclicGMP-AMP (cGAMP) produced by theDNA sensor cGAMP synthase (cGAS)2-5. cGAMP-induced high-order oligomerization and translocation of STING from the endoplasmic reticulum to theGolgi and post-Golgi vesicles are critical for STING activation6-11. Other studies have shown that phosphatidylinositol phosphates (PtdInsPs) and cholesterol also have important roles in STING activation, but the underlying mechanisms remain unclear12-17. Here we demonstrate that cGAMP-induced high-order oligomerization of STING is enhanced strongly by phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2 and PtdIns(4,5)P2, and by PtdIns4P to a lesser extent. Our cryo-electron microscopy structures reveal that PtdInsPs together with cholesterol bind at the interface between STING dimers, directly promoting the high-order oligomerization. The structures also provide an explanation for the preference of the STING oligomer to different PtdInsPs. Mutational and biochemical analyses confirm the binding modes of PtdInsPs and cholesterol and their roles in STING activation. Our findings shed light on the regulatory mechanisms of STING mediated by specific lipids, which may underlie the role of intracellular trafficking in dictating STING signalling.