Murine models of erythroid 5ALA synthesis disorders and their conditional synthetic lethal dependency on pyridoxine.

X-linked sideroblastic anemia (XLSA) and X-linked protoporphyria (XLPP) are uncommon diseases caused by loss-of-function and gain-of-function mutations, respectively, in the erythroid form of 5-aminolevulinic acid synthetase, ALAS2, which encodes the first enzyme in heme biosynthesis. A related sideroblastic anemia is due to mutations in SLC25A38, which supplies mitochondrial glycine for ALAS2 (SLC25A38-CSA). The lack of viable animal models has limited studies on the pathophysiology and development of therapies for these conditions. Here, using CRISPR-CAS9 gene editing technology, we have generated knock-in mouse models that recapitulate the main features of XLSA and XLPP, and, using conventional conditional gene targeting in embryonic stem cells, we also developed a faithful model of the SLC25A38-CSA. In addition to examining the phenotypes and natural history of each disease, we determine the effect of restriction or supplementation of dietary pyridoxine (vitamin B6), the essential cofactor of ALAS2, on the anemia and porphyria. In addition to the well-documented response of XLSA mutations to pyridoxine supplementation, we also demonstrate the relative insensitivity of the XLPP porphyria, severe sensitivity of the XLSA models, and an extreme hypersensitivity of the SLC25A38-CSA model to pyridoxine deficiency, a phenotype that is not shared with another mouse hereditary anemia model, Hbbth3/+ -thalassemia intermedia. Thus, in addition to generating animal models useful for examining the pathophysiology and treatment of these diseases, we have uncovered an unsuspected conditional synthetic lethality between the heme synthesis-related CSAs and pyridoxine deficiency. These findings have the potential to inform novel therapeutic paradigms for the treatment of these diseases.

Globalizing transit worker stress.

Health scientists have claimed that urban transit workers suffer from higher rates of stress-related disease than workers in most other occupations. This paper examines how a network of scientists and labor organizers constructed the problem of transit worker stress as a global phenomenon. According to study participants, transit workers worldwide are subject to a similar set of stress-related risks, which can serve as a basis for worker solidarity. This paper analyzes how the concept of stress has been used to identify pathogenic environments and considers anthropological claims that the concept often abstracts and depoliticizes harmful arrangements. The findings show that scientists and labor organizers use the stress concept to construct a figure of a universally at-risk transit worker that serves the ends of transnational labor organizing. At the same time, by focusing on the case of San Francisco's transit workers, this analysis shows that a persistent association between stress and 'hard work'-in both lay and scientific discourses-may block recognition of stress-related harms for transit workers who are accused of being lazy and overpaid.

Heterotopic Ossification Is Associated with Painful Neuromas in Transtibial Amputees Undergoing Surgical Treatment of Symptomatic Neuromas.

BACKGROUND: A relationship between nerve and osseous regeneration has been described. During the surgical treatment of symptomatic neuroma in transtibial amputees, we have noticed that heterotopic ossification (HO) depicted on preoperative radiographs appears to be associated with the location of symptomatic neuromas in both the peroneal and tibial nerve distributions. METHODS: Data were collected for transtibial amputees who underwent surgical management of symptomatic neuroma and were prospectively enrolled from 2018 through 2023. Preoperative radiographs were assessed for the presence of HO located at the distal fibula and tibia. The presence of a peroneal and/or tibial neuroma was based on findings contained within the operative reports. Pain levels were measured on a numeric rating scale (0-10). RESULTS: Sixty-five limbs of 62 amputees were include. Peroneal neuroma and presence of fibular HO (P=0.001), and tibial neuroma and presence of tibial HO (P=0.038) demonstrated an association. The odds of having a symptomatic peroneal neuroma with fibular HO present are greater than the odds of a symptomatic peroneal neuroma when fibular HO is absent (OR 9.3; 95%CI [1.9-45.6], P=0.006). Pre-operative pain scores were significantly higher for all patients with HO (P<0.001), those with fibular HO (P<0.001), and those with tibial HO (P<0.001), compared to patients without HO. CONCLUSIONS: In patients with symptomatic neuromas, preoperative pain was worse when HO was present in the transtibial amputee's residual limb. Further research on the neuroma-HO-complex in symptomatic amputees is required. LEVEL OF EVIDENCE: Therapeutic Level IV.

Comprehensive Genomic Analysis Identifies a Diverse Landscape of Sideroblastic and Nonsideroblastic Iron-Related Anemias with Novel and Pathogenic Variants in an Iron-Deficient Endemic Setting.

Inherited iron metabolism defects are possibly missed or underdiagnosed in iron-deficient endemic settings because of a lack of awareness or a methodical screening approach. Hence, we systematically evaluated anemia cases (2019 to 2021) based on clinical phenotype, normal screening tests (high-performance liquid chromatography, α gene sequencing, erythrocyte sedimentation rate, C-reactive protein, and tissue transglutaminase), and abnormal iron profile by targeted next-generation sequencing (26-gene panel) supplemented with whole-exome sequencing, multiplex ligation probe amplification/mitochondrial DNA sequencing, and chromosomal microarray. Novel variants in ALAS2, STEAP3, and HSPA9 genes were functionally validated. A total of 290 anemia cases were screened, and 41 (14%) enrolled for genomic testing as per inclusion criteria. Comprehensive genomic testing revealed pathogenic variants in 23 of 41 cases (56%). Congenital sideroblastic anemia was the most common diagnosis (14/23; 61%), with pathogenic variations in ALAS2 (n = 6), SLC25A38 (n = 3), HSPA9 (n = 2) and HSCB, SLC19A2, and mitochondrial DNA deletion (n = 1 each). Nonsideroblastic iron defects included STEAP3-related microcytic anemia (2/23; 8.7%) and hypotransferrenemia (1/23; 4.3%). A total of 6 of 22 cases (27%) revealed a non-iron metabolism gene defect on whole-exome sequencing. Eleven novel variants (including variants of uncertain significance) were noted in 13 cases. Genotype-phenotype correlation revealed a significant association of frameshift/nonsense/splice variants with lower presentation age (0.8 months versus 9 years; P < 0.01) compared with missense variants. The systematic evaluation helped uncover an inherited iron defect in 41% (17/41) of cases, suggesting the need for active screening and awareness for these rare diseases in an iron-deficient endemic population.

True-Positive 18F-Flotufolastat Lesions in Patients with Prostate Cancer Recurrence with Baseline-Negative Conventional Imaging: Results from the Prospective, Phase 3, Multicenter SPOTLIGHT Study.

18F-rhPSMA-7.3 (18F-flotufolastat) is a high-affinity prostate-specific membrane antigen-targeted diagnostic radiopharmaceutical for PET imaging in patients with prostate cancer. Here, we report findings from the SPOTLIGHT study (NCT04186845), assessing the performance of 18F-flotufolastat PET/CT for identifying prostate-specific membrane antigen-positive lesions confirmed by standard of truth (SoT) in men with biochemical recurrence of prostate cancer and negative conventional imaging at baseline. Methods: Men with biochemical recurrence received 296 MBq of 18F-flotufolastat intravenously and then underwent PET/CT 50-70 min later. 18F-flotufolastat PET/CT findings were evaluated by 3 masked central readers and verified using histopathology or follow-up confirmatory imaging (CT, MRI, bone scan, or 18F-fluciclovine PET/CT) as the SoT. The present analysis evaluated all patients who had negative conventional imaging at baseline, underwent 18F-flotufolastat PET/CT, and had SoT verification by histopathology or follow-up confirmatory imaging to report detection rate (DR), which is the number of patients with at least 1 PET-positive lesion, divided by the number of evaluable patients, and verified DR (VDR), which is the proportion of patients with at least 1 true-positive lesion as verified by SoT, of all patients scanned (PET-positive and PET-negative scans). DR and VDR were calculated and stratified according to prior therapy. Majority read data (agreement between ≥2 readers) are reported. Results: In total, 171 patients with negative baseline conventional imaging and SoT by histopathology or post-PET confirmatory imaging were evaluated. By majority read, the overall 18F-flotufolastat DR among these patients was 95% (163/171; 95% CI, 91.0%-98.0%), and 110 of 171 of these patients had at least 1 true-positive lesion identified (VDR, 64%; 95% CI, 56.7%-71.5%). In the postprostatectomy group (133/171), 8.3% of patients had at least 1 true-positive lesion in the prostate bed, 28% in pelvic lymph nodes, and 35% in other sites. Among those who had received radiotherapy (36/171), 50% of patients had true-positive detections in the prostate, 8.3% in pelvic lymph nodes, and 36% in other sites. Conclusion: 18F-flotufolastat frequently identified true-positive prostate cancer lesions in patients with negative conventional imaging. 18F-flotufolastat may help to better define sites of disease recurrence and inform salvage therapy decisions than does conventional imaging, potentially leading to improved outcomes.

Prostate Cancer Foundation Screening Guidelines for Black Men in the United States.

BACKGROUND: In the United States, Black men are at highest risk for being diagnosed with and dying from prostate cancer. Given this disparity, we examined relevant data to establish clinical prostate-specific antigen (PSA) screening guidelines for Black men in the United States. METHODS: A comprehensive literature search identified 1848 unique publications for screening. Of those screened, 287 studies were selected for full-text review, and 264 were considered relevant and form the basis for these guidelines. The numbers were reported according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. RESULTS: Three randomized controlled trials provided Level 1 evidence that regular PSA screening of men 50 to 74 years of age of average risk reduced metastasis and prostate cancer death at 16 to 22 years of follow-up. The best available evidence specifically for Black men comes from observational and modeling studies that consider age to obtain a baseline PSA, frequency of testing, and age when screening should end. Cohort studies suggest that discussions about baseline PSA testing between Black men and their clinicians should begin in the early 40s, and data from modeling studies indicate prostate cancer develops 3 to 9 years earlier in Black men compared with non-Black men. Lowering the age for baseline PSA testing to 40 to 45 years of age from 50 to 55 years of age, followed by regular screening until 70 years of age (informed by PSA values and health factors), could reduce prostate cancer mortality in Black men (approximately 30% relative risk reduction) without substantially increasing overdiagnosis. CONCLUSIONS: These guidelines recommend that Black men should obtain information about PSA screening for prostate cancer. Among Black men who elect screening, baseline PSA testing should occur between ages 40 and 45. Depending on PSA value and health status, annual screening should be strongly considered. (Supported by the Prostate Cancer Foundation.).

Folate depletion induces erythroid differentiation through perturbation of de novo purine synthesis.

Folate, an essential vitamin, is a one-carbon acceptor and donor in key metabolic reactions. Erythroid cells harbor a unique sensitivity to folate deprivation, as revealed by the primary pathological manifestation of nutritional folate deprivation: megaloblastic anemia. To study this metabolic sensitivity, we applied mild folate depletion to human and mouse erythroid cell lines and primary murine erythroid progenitors. We show that folate depletion induces early blockade of purine synthesis and accumulation of the purine synthesis intermediate and signaling molecule, 5'-phosphoribosyl-5-aminoimidazole-4-carboxamide (AICAR), followed by enhanced heme metabolism, hemoglobin synthesis, and erythroid differentiation. This is phenocopied by inhibition of folate metabolism using the inhibitor SHIN1, and by AICAR supplementation. Mechanistically, the metabolically driven differentiation is independent of mechanistic target of rapamycin complex 1 (mTORC1) and adenosine 5'-monophosphate-activated protein kinase (AMPK) and is instead mediated by protein kinase C. Our findings suggest that folate deprivation-induced premature differentiation of erythroid progenitor cells is a molecular etiology to folate deficiency-induced anemia.