Structural snapshots of base excision by the cancer-associated variant MutY N146S reveal a retaining mechanism.

DNA glycosylase MutY plays a critical role in suppression of mutations resulted from oxidative damage, as highlighted by cancer-association of the human enzyme. MutY requires a highly conserved catalytic Asp residue for excision of adenines misinserted opposite 8-oxo-7,8-dihydroguanine (OG). A nearby Asn residue hydrogen bonds to the catalytic Asp in structures of MutY and its mutation to Ser is an inherited variant in human MUTYH associated with colorectal cancer. We captured structural snapshots of N146S Geobacillus stearothermophilus MutY bound to DNA containing a substrate, a transition state analog and enzyme-catalyzed abasic site products to provide insight into the base excision mechanism of MutY and the role of Asn. Surprisingly, despite the ability of N146S to excise adenine and purine (P) in vitro, albeit at slow rates, N146S-OG:P complex showed a calcium coordinated to the purine base altering its conformation to inhibit hydrolysis. We obtained crystal structures of N146S Gs MutY bound to its abasic site product by removing the calcium from crystals of N146S-OG:P complex to initiate catalysis in crystallo or by crystallization in the absence of calcium. The product structures of N146S feature enzyme-generated ß-anomer abasic sites that support a retaining mechanism for MutY-catalyzed base excision.

Association of parity with the timing and type of menopause: A longitudinal cohort study.

We investigated the time-varying association between parity and timing of natural menopause, surgical menopause, and premenopausal hysterectomy among 23,728 women aged 40-65 years at enrollment in the Alberta's Tomorrow Project cohort study (2000-2022), using flexible parametric survival analysis. Overall, natural menopause was most common by study end (57.2%), followed by premenopausal hysterectomy (11.4%) and surgical menopause (5.3%). Risks of natural menopause before age 50 years were elevated for 0 births (adjusted hazard ratio at age 45: 1.33, 95% CI 1.18-1.49) and 1 birth (age 45: 1.21, 1.07-1.38), but similar for ≥3 births (age 45: 0.95, 0.85-1.06), compared to 2 births (reference). Elevated risks of surgical menopause before age 45 years for 0 births (age 40: 1.37, 1.09-1.69) and 1 birth (age 40: 1.11, 0.85-1.45) attenuated when excluding women with past infertility or recurrent pregnancy loss, and reduced risks were observed over time for ≥3 births (age 50: 0.84, 0.75-0.94). Risks of premenopausal hysterectomy were lower before age 50 years for 0 births (age 45: 0.82, 0.76-0.88) but elevated after age 40 years for ≥3 births (age 50: 1.25, 1.08-1.45). These complex associations necessitate additional research on the sociobiological impacts of childbearing on gynecologic health.

Ligand-induced native G-quadruplex stabilization impairs transcription initiation.

G-quadruplexes (G4s) are noncanonical DNA secondary structures formed through the self-association of guanines, and G4s are distributed widely across the genome. G4 participates in multiple biological processes including gene transcription, and G4-targeted ligands serve as potential therapeutic agents for DNA-targeted therapies. However, genome-wide studies of the exact roles of G4s in transcriptional regulation are still lacking. Here, we establish a sensitive G4-CUT&Tag method for genome-wide profiling of native G4s with high resolution and specificity. We find that native G4 signals are cell type-specific and are associated with transcriptional regulatory elements carrying active epigenetic modifications. Drug-induced promoter-proximal RNA polymerase II pausing promotes nearby G4 formation. In contrast, G4 stabilization by G4-targeted ligands globally reduces RNA polymerase II occupancy at gene promoters as well as nascent RNA synthesis. Moreover, ligand-induced G4 stabilization modulates chromatin states and impedes transcription initiation via inhibition of general transcription factors loading to promoters. Together, our study reveals a reciprocal genome-wide regulation between native G4 dynamics and gene transcription, which will deepen our understanding of G4 biology toward therapeutically targeting G4s in human diseases.

Hysterectomy versus Uterine Preservation for Pelvic organ prolapse Surgery (HUPPS): A prospective cohort study.

BACKGROUND: One in five females will have surgery to treat pelvic organ prolapse in their lifetime. Uterine-preserving surgery involving suspension of the uterus is an increasingly popular alternative to the traditional use of hysterectomy with vaginal vault suspension to treat pelvic organ prolapse; however, comparative evidence with native tissue repairs remains limited in scope and quality. OBJECTIVE: To compare 1-year outcomes between hysterectomy-based and uterine-preserving native tissue prolapse surgeries performed through minimally invasive approaches. STUDY DESIGN: We used a non-randomized design with patients self-selecting their surgical group to integrate a pragmatic, patient-centred, and autonomy-focused approach. Participants chose between uterine-preserving surgery or hysterectomy-based surgery, guided by neutral, evidence-based discussions and individualized decision-making, with support from fellowship-trained urogynecologists. Inverse probability of treatment weighting based on high-dimensional propensity scores was used to balance baseline differences across surgical groups in an effort to resemble a randomized clinical trial. A prospective cohort study of 321 participants with stage ≥2 prolapse involving the uterus who desired surgical treatment were recruited between 2020 and 2022 and followed to 1 year (retention >90%). Patients chose to receive uterine-preserving POP surgery through hysteropexy (n=151) or hysterectomy with vaginal vault suspension (n=170; reference group), with repair of anterior and/or posterior prolapse if indicated. The primary outcome was anatomic prolapse recurrence within one year, defined as apical descent ≥50% of the total vaginal length. Secondary outcomes were peri-operative, functional, clinical, and healthcare outcomes measured at 6 weeks and 1 year. Inverse probability of treatment weighted linear regression and modified Poisson regression were used to estimate adjusted mean differences (aMD) and relative risks (aRR), respectively. RESULTS: Apical anatomic recurrence rates at 1 year were 17.2% following hysterectomy and 7.5% following uterine-preservation, resulting in an adjusted relative risk of 0.35 (95% CI 0.15, 0.83). Uterine-preserving surgery was associated with shorter length of surgery (aMD -0.68 hours [-0.80, -0.55]) and hospitalization (aMD -4.34 hours [-7.91, -0.77]), less use of any opioids within 24 hours (aRR 0.79 [0.65, 0.97]), and fewer procedural complications (aRR 0.19 [0.04, 0.83]) than hysterectomy. Up to 1 year, uterine-preserving surgery was associated with lower risk of composite recurrence (stage ≥2 prolapse in any compartment or retreatment; aRR 0.47 [0.32, 0.69]) than hysterectomy, driven by anatomic outcomes. There were no clinically meaningful differences in functional or healthcare outcomes between surgical groups. CONCLUSION: This study adds real-world evidence to the growing body of research supportive of uterine-preserving surgery as a safe, efficient, and effective alternative to hysterectomy during native tissue prolapse repair. Given mounting evidence on safety, efficiency, and effectiveness of uterine-preserving surgery and its alignment with the preferences of approximately half of patients to keep their uterus, the standard of care should include routine offering and patient choice between uterine-preserving and hysterectomy-based surgery for pelvic organ prolapse.

Unilateral Oophorectomy and Age at Natural Menopause: A Longitudinal Community-Based Cohort Study.

OBJECTIVE: To determine the association between unilateral oophorectomy (UO) and age at natural menopause. DESIGN: Secondary analysis of survey data from Alberta's Tomorrow Project (2000-2022). SETTING: Prospective cohort study in Alberta, Canada. POPULATION: 23 630 women; 548 experienced UO and 23 082 did not experience UO. METHODS: Flexible parametric survival analysis was used to analyse age at natural menopause, and logistic regression was used to analyse early menopause and premature ovarian insufficiency by UO status, controlling for birth year, parity, age at menarche, past infertility, hormonal contraceptive use and smoking. MAIN OUTCOME MEASURES: Age at natural menopause occurred by a final menstrual period without medical cause and sub-classified as early menopause (< 45 years) and premature ovarian insufficiency (< 40 years). RESULTS: Compared to no UO, any UO was associated with elevated risk of earlier age at natural menopause, which was strongest in early midlife (adjusted HR at age 40 1.71, 95% CI 1.31-2.19) and diminished over time. Compared to age 55 years at UO, risks of earlier age at natural menopause were largest and uniform in magnitude when UO occurred between approximately ages 20-40 years (adjusted HR for UO at age 30 2.32, 1.46-3.54) and then diminished as age at UO approached the average age at natural menopause. Any UO was associated with higher odds of early menopause (adjusted OR 1.90, 1.30-2.79) and premature ovarian insufficiency (adjusted OR 3.75, 1.72-8.16). CONCLUSIONS: Unilateral oophorectomy is associated with earlier age at natural menopause, particularly when performed before 40 years of age.

Babcock versus Scissor Tensioning for Retropubic Mid-Urethral Slings: Comparing Two Intra-Operative Techniques Through 5 Years of Follow-Up.

INTRODUCTION AND HYPOTHESIS: The objective was to determine if mid-urethral sling (MUS) tensioning with a Mayo Scissor as a sub-urethral spacer compared with a Babcock clamp holding a loop of tape under the urethra results in differences in patient-reported outcomes and rates of repeat surgery over a 5-year follow-up. METHODS: Follow-up 5 years after a randomized clinical trial, utilizing primary data collection linked to administrative health data, was carried out to create a longitudinal cohort. The primary outcome was participant-reported bothersome SUI symptoms, as defined by the Urogenital Distress Inventory (UDI-6) questionnaire. Secondary outcomes included participant-reported bothersome overactive bladder (OAB) scores, median scores of three validated urinary symptom questionnaires, and rates of subsequent surgery determined through patient report and administrative data. RESULTS: Two hundred and sixty (81.8%) of the original study participants provided participant-reported data at 5 years. Administrative data linkage was completed for all of the original participants (n = 318). Demographic characteristics remained similar in the two groups at the 5-year follow-up mark. No differences existed in the primary outcome of reported bothersome SUI symptoms (30.8% Scissors vs 26.8% Babcock, p = 0.559), proportion of participants with bothersome OAB, the median scores of three validated bladder questionnaires, or in rates and cumulative incidence of recurrent MUS surgery or surgical revision of mesh-related complications. CONCLUSION: Both the Scissor and Babcock tensioning techniques provided comparable outcomes at 5 years post-MUS surgery. The information from this study allows surgeons to better decide which technique to adopt in their practice, providing confidence in longer-term cure and safety.

Education level is associated with the occurrence and timing of hysterectomy: A cohort study of Canadian women.

INTRODUCTION: Hysterectomy is a common surgery with discernible practice variations that could be influenced by socioeconomic factors. We examined the association between level of educational attainment and the occurrence and timing of hysterectomy in Canadian women. MATERIAL AND METHODS: We conducted a prospective cohort study of 30 496 females in the Alberta's Tomorrow Project (2000-2015) followed approximately every 4 years using self-report questionnaires. Educational attainment was defined as high school diploma or less, college degree, university degree (reference group), and postgraduate degree. We used logistic regression analyzing hysterectomy occurrence at any time and before menopause, separately, and flexible parametric survival models analyzing hysterectomy timing with age as the time scale. Multivariable models controlled for race/ethnicity, rural/urban residence, parity, oral contraceptive use, and smoking. RESULTS: Overall, 39.1% of females reported a high school diploma or less, 28.9% reported a college degree, 23.5% reported a university degree, and 8.5% reported a postgraduate degree. A graded association was observed between lower education and higher odds of hysterectomy (high school or less: adjusted odds ratio [AOR] 1.68, 95% CI 1.55-1.82; college degree: AOR 1.58, 95% CI 1.45-1.72); results were similar for premenopausal hysterectomy. A graded association between lower education and earlier timing of hysterectomy was also observed up to approximately age 60 (eg at age 40: high school or less adjusted hazard ratio [AHR] 1.61, 95% CI 1.49-1.75; college degree AHR 1.53, 95% CI 1.40-1.67). CONCLUSIONS: Women with lower levels of education were more likely to experience hysterectomy, including hysterectomy before menopause and at younger ages.

Hydrogels as Durable Anti-Icing Coatings Inhibit and Delay Ice Nucleation.

The accumulation of ice on surfaces brings dangerous and costly problems to our daily life. Thus, it would be desirable to design anti-icing coatings for various surfaces. We report a durable anti-icing coating based on mussel-inspired chemistry, which is enabled via fabricating a liquid water layer, achieved by modifying solid substrates with the highly water absorbing property of sodium alginate. Dopamine, the main component of the mussel adhesive protein, is introduced to anchor the sodium alginate in order to render the coating applicable to all types of solid surfaces. Simultaneously, it serves as the cross-linking agent for sodium alginate; thus, the cross-linking degree of the coatings could be easily varied. The non-freezable and freezable water in the coatings with different cross-link degrees all remain liquid-like at subzero conditions and synergistically fulfill the aim of decreasing the temperature of ice nucleation. These anti-icing coatings display excellent stability even under harsh conditions. Furthermore, these coatings can be applied to almost all types of solid surfaces and have great promise in practical applications.

CT perfusion for Assessment of poor Neurological outcome in Comatose Cardiac Arrest Patients (CANCCAP): protocol for a prospective study.

INTRODUCTION: Cardiac arrest remains one of the most common causes of death with the majority occurring outside of hospitals (out of hospital cardiac arrest). Despite advancements in resuscitation management, approximately 50% of comatose cardiac arrest patients (CCAP) will suffer a severe unsurvivable brain injury. To assess brain injury, a neurological examination is conducted, however, its reliability in predicting outcomes in the first days following cardiac arrest is limited. Non-contrast CT is the most employed scan to assess hypoxic changes, even though it is not sensitive to early hypoxic-ischaemic changes in the brain. CT perfusion (CTP) has shown high sensitivity and specificity in brain death patients, although its use in predicting poor neurological outcome in CCAP has not yet been explored. The purpose of this study is to validate CTP for predicting poor neurological outcome (modified Rankin scale, mRS≥4) at hospital discharge in CCAP. METHODS AND ANALYSIS: The CT Perfusion for Assessment of poor Neurological outcome in Comatose Cardiac Arrest Patients study is a prospective cohort study funded by the Manitoba Medical Research Foundation. Newly admitted CCAP receiving standard Targeted Temperature Management are eligible. Patients undergo a CTP at the same time as the admission standard of care head CT. Admission CTP findings will be compared with the reference standard of an accepted bedside clinical assessment at the time of admission. Deferred consent will be used. The primary outcome is a binary outcome of good neurological status, defined as mRs<4 or poor neurological status (mRs≥4) at hospital discharge. A total of 90 patients will be enrolled. ETHICS AND DISSEMINATION: This study has been approved by the University of Manitoba Health Research Ethics Board. The findings from our study will be disseminated through peer-reviewed journals and presentations at local rounds, national and international conferences. The public will be informed at the end of the study. TRIAL REGISTRATION NUMBER: NCT04323020.

G-quadruplexes sense natural porphyrin metabolites for regulation of gene transcription and chromatin landscapes.

BACKGROUND: G-quadruplexes (G4s) are unique noncanonical nucleic acid secondary structures, which have been proposed to physically interact with transcription factors and chromatin remodelers to regulate cell type-specific transcriptome and shape chromatin landscapes. RESULTS: Based on the direct interaction between G4 and natural porphyrins, we establish genome-wide approaches to profile where the iron-liganded porphyrin hemin can bind in the chromatin. Hemin promotes genome-wide G4 formation, impairs transcription initiation, and alters chromatin landscapes, including decreased H3K27ac and H3K4me3 modifications at promoters. Interestingly, G4 status is not involved in the canonical hemin-BACH1-NRF2-mediated enhancer activation process, highlighting an unprecedented G4-dependent mechanism for metabolic regulation of transcription. Furthermore, hemin treatment induces specific gene expression profiles in hepatocytes, underscoring the in vivo potential for metabolic control of gene transcription by porphyrins. CONCLUSIONS: These studies demonstrate that G4 functions as a sensor for natural porphyrin metabolites in cells, revealing a G4-dependent mechanism for metabolic regulation of gene transcription and chromatin landscapes, which will deepen our knowledge of G4 biology and the contribution of cellular metabolites to gene regulation.

Molecular evolution of paclitaxel biosynthetic genes TS and DBAT of Taxus species.

Evolutionary patterns of sequence divergence were analyzed in genes from the conifer genus Taxus (yew), encoding paclitaxel biosynthetic enzymes taxadiene synthase (TS) and 10-deacetylbaccatin III-10 beta-O-acetyltransferase (DBAT). N-terminal fragments of TS, full-length DBAT and internal transcribed spacer (ITS) were amplified from 15 closely related Taxus species and sequenced. Premature stop codons were not found in TS and DBAT sequences. Codon usage bias was not found, suggesting that synonymous mutations are selectively neutral. TS and DBAT gene trees are not consistent with the ITS tree, where species formed monophyletic clades. In fact, for both genes, alleles were sometimes shared across species and parallel amino acid substitutions were identified. While both TS and DBAT are, overall, under purifying selection, we identified a number of amino acids of TS under positive selection based on inference using maximum likelihood models. Positively selected amino acids in the N-terminal region of TS suggest that this region might be more important for enzyme function than previously thought. Moreover, we identify lineages with significantly elevated rates of amino acid substitution using a genetic algorithm. These findings demonstrate that the pattern of adaptive paclitaxel biosynthetic enzyme evolution can be documented between closely related Taxus species, where species-specific taxane metabolism has evolved recently.

Metal-catechol complexes mediate ice nucleation.

The capability of mediating ice nucleation is pertinent to a broad range of fields. Herein, inspired by metal-catechol coordination found in adhesive proteins in which catechol moieties can construct strong complexes with a diverse array of metal ions, we develop a platform for mediating ice nucleation based on metal-catechol complexes and demonstrate that ice nucleation can be successively mediated by varying the characteristics and valence of the metal in metal-catechol complexes.

Phylogenetic relationships of the genus Taxus inferred from chloroplast intergenic spacer and nuclear coding DNA.

A cladistic analysis of the medicinal plant Taxus, using the sequences of one chloroplast (trnS-trnQ spacer) and three nuclear taxadiene synthase (TS), 10-deacetylbaccatin III-10beta-O-acetyltransferase (DBAT), and 18S rDNA) molecular markers, was carried out by distance, parsimony, likelihood, and Bayesian methods. Three of the four New World species (T. brevifolia, T. floridana and T. globosa) form a well-supported clade, whereas T. canadensis initially branches-appearing distantly related to both Old World taxa and New World species. In Asia, Taxus chinensis, T. mairei, T. sumatrana and T. wallichiana cluster together and are sister to a clade containing T. baccata and T. contorta. Taxus yunnanensis is more closely related to T. wallichiana than to four other Taxus species in our study from China; T. contorta is closer to the Euro-Mediterranean T. baccata than to the Asian species. This study provides a genetic method for authentication of economically important Taxus species and proposes a robust phylogenetic hypothesis for the genus. Using trnS-trnQ spacer sequences, we were able to distinguish T. mairei from all other species of Taxus.