Complex Repair Research Articles

Immunostaining for Mismatch Repair Complex Proteins Impacts on Clinical-Pathological Characteristics and Prognosis of Adenoid Cystic Carcinoma of Salivary Glands.

To evaluate the influence of MMR proteins on clinicopathological characteristics and prognosis of salivary gland adenoid cystic carcinoma (ACC). The solid pattern of ACC showed lower expression for MSH2 (p = 0.039). Significant imbalance in MSH2/MSH6 immunostaining was observed in all histological patterns (p < 0.001), and imbalance in PMS2/MLH1 immunostaining was observed in the cribriform pattern (p = 0.011). The presence of capsule was associated with high expression of MSH6 (p = 0.019), MLH1 (p = 0.045) and PMS2 (p = 0.009). The absence of cribriform pattern (p = 0.002) and capsule pattern (p = 0.025), as well as low expression for MSH6 (p = 0.006) and PMS2 (p = 0.037) were associated with lower overall survival. In multivariate analysis, loss of MSH2 (p = 0.039) and MLH1 (p = 0.017) were significantly associated with worse overall survival. Twenty-four ACC were clinical-pathologically evaluated and we perform immunohistochemistry for MSH2, MSH6, PMS2 and MLH1. Percentage counting of positive cells was performed in 10 fields of each histological pattern (cribriform, tubular and solid) and the averages of the 30 fields were considered for evaluation with other clinical-pathological variables (Kruskal-Wallis/Dunn, Friedman/Dunn, chi-square, Log-Rank Mantel-Cox tests and Cox regression; SPSS v20.0, p < 0.05). Salivary glands' ACC shows imbalance of the MMR complex and loss of expression of its components is associated with the overall survival of these patients.

Tough and anisotropic Janus hydrogel for tendon injury repair with controlled release of bFGF in tendon microenvironment

To address the high complexity and challenging nature of large-scale tendon injury repair, an innovative Janus structured hydrogel patch (JAHP@bFGF) was designed in this study. The patch combines microenvironmental responsiveness with efficient repair function, aiming to optimise and accelerate the tendon healing process. The outer layer is a PVA/SA/Na3Cit hydrogel with excellent mechanical properties, protein resistance, and low friction, which provides firm support to the tendon and reduces adhesions to ensure the recovery of gliding function. The inner layer of TCSB@bFGF microgel responds intelligently to changes in the microenvironment, precisely regulates the release of bFGF, promotes cell proliferation and migration, accelerates tissue regeneration, and has high adhesion strength and antimicrobial properties, which significantly reduces the risk of postoperative infection. Experimental results show that JAHP@bFGF significantly optimises the healing process, accelerates the repair speed and improves the repair quality under simulated large-scale tendon injury conditions. The unique Janus surface design and the intelligent drug release function, in synergy, not only bring new hope to patients with large-scale tendon injuries, but also provide an important reference for the application of biomedical materials in the repair of complex tissues, which heralds the arrival of the era of more efficient and personalised tendon repair.

Special-form radial collateral artery perforator flaps for the reconstruction of complex hand defects

BackgroundThe reconstruction of complex wounds of the hand still has challenges in achieving aesthetic, functional and sensory recovery. We presented our experience of using the polyfoliate and chimeric radial collateral artery perforator flaps (RCAPF) to repair complex hand defects, aiming to explore the feasibility of special-form RCAPFs in hand coverage and enhance the comprehension of their respective indications.MethodsFrom June 2014 to March 2021, 26 cases (19 males and 7 females, mean 44.4 years) underwent defect and sensation reconstruction of their hands with special-form RCAPFs, which manifested as multiple adjacent or irregular single wounds and composite tissue defects complicated with a degree of nerve injury. The clinical effects of the free RCAPFs were evaluated by integrating the postoperative and long-term follow-up outcomes of all cases.ResultsAltogether 8 polyfoliate flaps, 17 chimeric flaps and 1 polyfoliate-chimeric flap were harvested. Of them, 23 flaps survived uneventfully in one stage. Venous congestion occurred in 3 cases, two of which survived through vascular exploration and another one was finally repaired by the contralateral RCAPF. The follow-up results showed that the appearance of both the recipient and donor sites mostly recovered satisfactory. All the bone flaps properly healed. The BMRC sensory evaluation results of all skin flaps were S4 in 8 flaps, S3 in 18 flaps, and S2 in 9 flaps.ConclusionsThe free RCAPFs can be designed in various forms with a reliable blood supply, contributing to reconstructing simple and multiple wounds of the hand with or without bone defects and dead space.

3D chitosan scaffolds loaded with ZnO nanoparticles for bone tissue engineering

Bone defect has always been a difficult problem in clinical work. According to the current research results, tissue engineered scaffolds with a single function, structure, and composition are not sufficient to repair complex bone defects. In this work, a three-dimensional (3D) chitosan degradable composite scaffold loaded with zinc oxide (ZnO) was constructed, and the effect of ZnO content on scaffold performance and osteogenesis was explored. The 3D composite scaffold was prepared by freeze-drying technology. The microstructure, porosity, degradation performance, release performance, swelling performance, cytotoxicity, cell adhesion and osteogenic ability of ZnO nanoparticles and chitosan (ZnONPs/CS) composite scaffolds were measured. The results show that an appropriate amount of ZnO may be helpful to regulate the stability and degradation characteristics of the scaffold to a certain extent. Moreover, the composite scaffold could release ZnO into the simulated body fluid environment. The appropriate amount of ZnO helps to promote the proliferation, adhesion, and osteogenic differentiation of MC3T3-E1 cells. At a ZnO content of 3wt%, both in vitro and vivo results showed relatively optimal biocompatibility and bioactivity of the scaffolds. This work could at least provide some positive insights for the selection of ZnO dosage, construction of chitosan-based 3D scaffolds, tissue engineering applications, and clinical treatment.

PARP1-TRIM44-MRN loop dictates the response to PARP inhibitors.

PARP inhibitors (PARPi) show selective efficacy in tumors with homologous recombination repair (HRR)-defects but the activation mechanism of HRR pathway in PARPi-treated cells remains enigmatic. To unveil it, we searched for the mediator bridging PARP1 to ATM pathways by screening 211 human ubiquitin-related proteins. We discovered TRIM44 as a crucial mediator that recruits the MRN complex to damaged chromatin, independent of PARP1 activity. TRIM44 binds PARP1 and regulates the ubiquitination-PARylation balance of PARP1, which facilitates timely recruitment of the MRN complex for DSB repair. Upon exposure to PARPi, TRIM44 shifts its binding from PARP1 to the MRN complex via its ZnF UBP domain. Knockdown of TRIM44 in cells significantly enhances the sensitivity to olaparib and overcomes the resistance to olaparib induced by 53BP1 deficiency. These observations emphasize the central role of TRIM44 in tethering PARP1 to the ATM-mediated repair pathway. Suppression of TRIM44 may enhance PARPi effectiveness and broaden their use even to HR-proficient tumors.

Disease-Specific Patient-Reported Quality of Life after Fenestrated/Branched Endovascular Aortic Aneurysm Repair

ObjectivesFenestrated-branched endovascular technology (F/B-EVAR) is increasingly used to repair complex aortic aneurysms. While reintervention, morbidity and mortality after F/B-EVAR have been well-characterized, studies on patient-reported quality of life (QOL) after F/B-EVAR have been limited in their use of non-specific instruments and measures. We report on disease-specific QOL in patients that underwent F/B-EVAR using a validated QOL survey for aortic aneurysms. MethodsProspectively maintained databases were used to contact living patients that underwent F/B-EVAR for pararenal or thoracoabdominal aortic aneurysms at two institutions. Eligible patients (n=286) were asked to complete a disease-specific QOL survey previously validated in patients that underwent repair of an infrarenal abdominal aortic aneurysm. An emotional impact score (EIS) from 0-100 was derived from the survey with higher scores indicating more emotional impact and worse QOL. Respondent behavior change following F/B-EVAR was evaluated in four domains (strenuous activity, travel, heavy lifting, and sexual activity) previously identified by patients to be most impacted by an aortic aneurysm. ResultsIn total, 234 patients (82%) completed surveys. Mean post-operative interval to survey completion was 3.4±2.8 years. Mean EIS was 16 (range 0-91) for all patients surveyed, with higher mean EIS among those within the first year after F/B-EVAR (20 vs 14). Most respondents demonstrated limited adverse emotional impact after F/B-EVAR. However, the 4th quartile of EIS was broad (22-91), indicating that a subset of respondents had significantly worse QOL after repair. While most patients reported no post-procedure change in each of the activity domains, over 40% of patients did report decrease in strenuous activity and heavy lifting after F/B-EVAR. Those with decreased activity after repair had corresponding deficiencies in disease-specific knowledge for the domains of heavy lifting (p<0.001) and sexual activity (p=0.17). ConclusionsThe majority of patients who underwent F/B-EVAR in this cohort had low emotional impact on their QOL after repair. One-quarter of patients did report significant post-procedure anxiety about their aneurysm, with improvement observed beyond one year after repair. Most patients reported unchanged or decreased activity levels following F/B-EVAR, and less aneurysm-specific patient knowledge was associated with decreased activity after repair. These findings are similar to those seen in prior work using this survey instrument in patients that underwent infrarenal aneurysm repair. This work confirms the feasibility of using this survey to evaluate QOL in patients with complex aortic disease. Longitudinal evaluation in these patients may identify those at high-risk for worse QOL after F/B-EVAR.

Toward Lower Repair Bandwidth and Optimal Repair Complexity of Piggybacking Codes With Small Sub-Packetization

Toward Lower Repair Bandwidth and Optimal Repair Complexity of Piggybacking Codes With Small Sub-Packetization

Micronuclear collapse from oxidative damage.

Chromosome-containing micronuclei are a hallmark of aggressive cancers. Micronuclei frequently undergo irreversible collapse, exposing their enclosed chromatin to the cytosol. Micronuclear rupture catalyzes chromosomal rearrangements, epigenetic abnormalities, and inflammation, yet mechanisms safeguarding micronuclear integrity are poorly understood. In this study, we found that mitochondria-derived reactive oxygen species (ROS) disrupt micronuclei by promoting a noncanonical function of charged multivesicular body protein 7 (CHMP7), a scaffolding protein for the membrane repair complex known as endosomal sorting complex required for transport III (ESCRT-III). ROS retained CHMP7 in micronuclei while disrupting its interaction with other ESCRT-III components. ROS-induced cysteine oxidation stimulated CHMP7 oligomerization and binding to the nuclear membrane protein LEMD2, disrupting micronuclear envelopes. Furthermore, this ROS-CHMP7 pathological axis engendered chromosome shattering known to result from micronuclear rupture. It also mediated micronuclear disintegrity under hypoxic conditions, linking tumor hypoxia with downstream processes driving cancer progression.

Critical residues in the Ku70 von Willebrand A domain mediate Ku interaction with the LigIV-XRCC4 complex in non-homologous end-joining

The Ku heterodimer (Ku70/Ku80) is central to the non-homologous end-joining (NHEJ) pathway. Ku binds to the broken DNA ends and promotes the assembly of the DNA repair complex. The N-terminal Ku70 von Willebrand A (vWA) domain is known to mediate protein-protein interactions important for the repair process. In particular, the D192 and D195 residues within helix 5 of the Ku70 vWA domain were shown to be essential for NHEJ function, although the precise role of these residues was not identified. Here, we set up a miniTurbo screening system to identify Ku70 D192/D195 residue-specific interactors in a conditional, human Ku70-knockout cell line in response to DNA damage. Using fusion protein constructs of Ku70 wild-type and mutant (D192A/D195R) with miniTurbo, we identified a number of candidate proximal interactors in response to DNA damage treatment, including DNA Ligase IV (LigIV), a known and essential NHEJ complex member. Interestingly, LigIV was enriched in our wildtype screen but not the Ku70 D192A/D195R screen, suggesting its interaction is disrupted by the mutation. Validation experiments demonstrated that the DNA damage-induced interaction between Ku70 and LigIV was disrupted by the Ku70 D192A/D195R mutations. Our findings provide greater detail about the interaction surface between the Ku70 vWA domain and LigIV and offer strong evidence that the D192 and D195 residues are important for NHEJ completion through an interaction with LigIV. Altogether, this work reveals novel potential proximal interactors of Ku in response to DNA damage and identifies Ku70 D192/D195 residues as essential for LigIV interaction with Ku during NHEJ.

ТЕНДЕНЦИИ И ПЕРСПЕКТИВЫ РАЗВИТИЯ РЫБОХОЗЯЙСТВЕННОГО КОМПЛЕКСА КАМЧАТСКОГО КРАЯ

The trends and prospects for the development of the fishery complex (FHC) of the Kamchatka Territory are explored through the prism of analyzing program documents at the federal and regional levels. The main focus of development is aimed at creating a high-tech fishing cluster, modernizing fish processing enterprises, updating the fleet and developing maritime logistics. Special attention is paid to the integration of ports into the cargo turnover of the Northern Sea Route (NSR) and the creation of a competitive ship repair complex. Social aspects include improving the region's personnel self-sufficiency and creating social facilities. Environmental initiatives such as recycling fish waste and creating protected areas are particularly considered. The article presents conclusions about the strengths and weaknesses of each program document.

Outcomes using inverted iliac limb bifurcate components in fenestrated/branched endografting

BackgroundThe use of standard bifurcate pieces in fenestrated/branched endovascular aortic repair (F/BEVAR) requires adequate length from the lowest branch or fenestration to the aortic bifurcation. In patients with prior aortic surgery, the aortic bifurcation is often artificially established in a more proximal position, compromising the infrarenal length, which hinders the placement of a standard bifurcate component below the fenestrated/branched component. Short bifurcate bodies using an inverted contralateral limb have been purpose-built to address this challenge. However, reported outcomes for this device remain limited, with specific concerns about the durability of the inverted iliac limb sealing region. We sought to evaluate outcomes of F/BEVAR using an investigational inverted iliac limb bifurcate, manufactured by Cook Medical. MethodsThis study was a retrospective review of prospectively maintained data from the US-Aortic Research Consortium from 2005 to 2022. Patients were included if they underwent F/BEVAR for thoracoabdominal or complex abdominal aortic aneurysms. Patients were excluded if they did not have a bifurcate device placed. Patients were then compared based on the use of an inverted iliac limb or standard bifurcate component. The primary outcome for this study was technical success. Secondary outcomes included 30-day mortality, freedom from ischemic leg complications, freedom from type I endoleaks (TIELs), freedom from type II endoleaks (TIIELs), freedom from type III endoleaks (TIIIELs), and graft component separations. ResultsA total of 1944 patients met study criteria with 442 (22.8%) inverted iliac limb bifurcates and 1502 (77.2%) standard bifurcates. Patients who received inverted iliac limbs were more likely to have had prior aortic surgery (63.8% vs 28.5%; P < .001). Patients receiving inverted iliac limbs had longer procedure times (265 minutes; interquartile range [IQR], 201-342 minutes vs 241 minutes; IQR, 186-313 minutes; P < .001), more contrast use (89 mL [IQR, 55-135 mL] vs 109 mL [IQR, 75-156 mL]; P < .001), and higher estimated blood loss (250 mL [IQR, 150-500 mL] vs 250 mL [IQR, 110-400 mL]; P = .042). There were no differences in rates of technical success (97.3% vs 96.1%; P = .310), rates of endoleaks upon completion of the case (18.0% vs 21.4%; P = .123), or 30-day mortality rates (1.8% vs 2.5%; P = .466) between patients receiving inverted iliac limb and standard bifurcated components. There were no differences in cumulative survival, freedom from limb ischemia, freedom from aneurysm rupture, and freedom from TIIIELs over the course of 5 years between patients receiving inverted bifurcates and standard bifurcated components. Patients with inverted iliac limb bifurcate components had decreased freedom from reinterventions, TIELs, and TIIELs. After adjustment for potential confounders, the use of an inverted iliac limb was not associated with reinterventions (hazard ratio,1.044; 95% confidence interval, 0.849-1.285; P = .682). There was a total of 2 component separations (0.1%) of the bifurcate component from the fenestrated/branched component over the study period, both of which occurred in the standard bifurcate components. ConclusionsThe use of investigational inverted iliac limb bifurcate components is a safe option with favorable mid-term outcomes in patients who are not anatomical candidates for standard bifurcate components. Patients undergoing investigational inverted iliac limb bifurcate component implantation had decreased freedom from reinterventions, which likely corresponds with the complexity of repair associated with them.

Somatic CpG hypermutation is associated with mismatch repair deficiency in cancer

Somatic hypermutation in cancer has gained momentum with the increased use of tumour mutation burden as a biomarker for immune checkpoint inhibitors. Spontaneous deamination of 5-methylcytosine to thymine at CpG dinucleotides is one of the most ubiquitous endogenous mutational processes in normal and cancer cells. Here, we performed a systematic investigation of somatic CpG hypermutation at a pan-cancer level. We studied 30,191 cancer patients and 103 cancer types and developed an algorithm to identify somatic CpG hypermutation. Across cancer types, we observed the highest prevalence in paediatric leukaemia (3.5%), paediatric high-grade glioma (1.7%), and colorectal cancer (1%). We discovered germline variants and somatic mutations in the mismatch repair complex MutSα (MSH2-MSH6) as genetic drivers of somatic CpG hypermutation in cancer, which frequently converged on CpG sites and TP53 driver mutations. We further observe an association between somatic CpG hypermutation and response to immune checkpoint inhibitors. Overall, our study identified novel cancer types that display somatic CpG hypermutation, strong association with MutSα-deficiency, and potential utility in cancer immunotherapy.

Image inpainting algorithm based on double curvature-driven diffusion model with P-Laplace operator.

The method of partial differential equations for image inpainting achieves better repair results and is economically feasible with fast repair time. Addresses the inability of Curvature-Driven Diffusion (CDD) models to repair complex textures or edges when the input image is affected by severe noise or distortion, resulting in discontinuous repair features, blurred detail textures, and an inability to deal with the consistency of global image content, In this paper, we have the CDD model of P-Laplace operator term to image inpainting. In this method, the P-Laplace operator is firstly introduced into the diffusion term of CDD model to regulate the diffusion speed; then the improved CDD model is discretized, and the known information around the broken region is divided into two weighted average iterations to get the inpainting image; finally, the final inpainting image is obtained by weighted averaging the two image inpainting images according to the distancing. Experiments show that the model restoration results in this paper are more rational in terms of texture structure and outperform other models in terms of visualization and objective data. Comparing the inpainting images with 150, 1000 and 100 iterations respectively, Total Variation(TV) model and the CDD model inpainting algorithm always has inpainting traces in details, and TV model can't meet the visual connectivity, but the algorithm in this paper can remove the inpainting traces well, TV model and the CDD model inpainting algorithm always have inpainting traces in details, and TV model can't meet the visual connectivity, but the algorithm in this paper can remove the inpainting traces well. Of the images used for testing, the highest PSNR reached 38.7982, SSIM reached 0.9407, and FSIM reached 0.9781, the algorithm not only inpainting the effect and, but also has fewer iterations.

Clustered DNA Damage and its Complexity: Tracking the History.

The concept of radiation-induced clustered damage in DNA has grown over the past several decades to become a topic of considerable interest across the scientific disciplines involved in studies of the biological effects of ionizing radiation. This paper, prepared for the 70th anniversary issue of Radiation Research, traces historical development of the three main threads of physics, chemistry, and biochemical/cellular responses that led to the hypothesis and demonstration that a key component of the biological effectiveness of ionizing radiation is its characteristic of producing clustered DNA damage of varying complexities. The physics thread has roots that started as early as the 1920s, grew to identify critical nanometre-scale clusterings of ionizations relevant to biological effectiveness, and then, by the turn of the century, had produced an extensive array of quantitative predictions on the complexity of clustered DNA damage from different radiations. Monte Carlo track structure simulation techniques played a key role through these developments, and they are now incorporated into many recent and ongoing studies modelling the effects of radiation. The chemistry thread was seeded by water-radiolysis descriptions of events in water as radical-containing "spurs," demonstration of the important role of the hydroxyl radical in radiation-inactivation of cells and the difficulty of protection by radical scavengers. This led to the concept and description of locally multiply damaged sites (LMDS) for DNA double-strand breaks and other combinations of DNA base damage and strand breakage that could arise from a spur overlapping, or created in very close proximity to, the DNA. In these ways, both the physics and the chemistry threads, largely in parallel, put out the challenge to the experimental research community to verify these predictions of clustered DNA damage from ionizing radiations and to investigate their relevance to DNA repair and subsequent cellular effects. The third thread, biochemical and cell-based research, responded strongly to the challenge by demonstrating the existence and biological importance of clustered DNA damage. Investigations have included repair of a wide variety of defined constructs of clustered damage, evaluation of mutagenic consequences, identification of clustered base-damage within irradiated cells, and identification of co-localization of repair complexes indicative of complex clustered damage after high-LET irradiation, as well as extensive studies of the repair pathways involved in repair of simple double-strand breaks. There remains, however, a great deal more to be learned because of the diversity of clustered DNA damage and of the biological responses.

Polymorphism in the matrix metallopeptidase genes is associated with coronary artery disease risk with concomitant metabolic syndrome

Background: Metabolic syndrome (MS) and its components are the reasons of the development and progression of cardiovascular diseases. Nowadays, the association between coronary artery disease and MS remains ambiguous. The central role of matrix metallopeptidases (MMP) in the metabolism of connective tissue proteins, cell matrix remodeling, tissue repair and other complex biochemical processes has been shown, which implies their involvement in the pathogenesis of cardiovascular diseases. The aim of the study: To study the associations of polymorphic variants in the MMP genes with the risk of stable coronary artery disease with concomitant metabolic syndrome. Materials and methods: 170 patients with stable coronary artery disease concomitant with a visceral type of obesity in combination with two or more pathological conditions (elevated serum blood glucose level, elevated serum blood cholesterol level, hypertension) were included in the case group. Conditionally healthy volunteers (n=182) were recruited in the control group. Genotyping of five polymorphic sites in the four genes MMP1 (rs514921), MMP3 (rs6796620 and rs626750), MMP9 (rs17576) and TIMP2 (rs2277698) was performed by real-time PCR. The serum blood level of MMP was measured by ELISA. Gene-gene interactions were analyzed using MDR v.3.0.2 software. Results: The frequency of heterozygous C/T genotype in the MMP3 gene (rs626750) was higher in the control group (37.90%) compared to the case group (23.20%), which indicates its protective effect on the risk of coronary artery disease with concomitant metabolic syndrome (OR=0.47, 95%CI 0.29-0.75). 2.6-fold increased risk of coronary artery disease with concomitant metabolic syndrome was demonstrated for carriers of the A/G genotype in the TIMP2 gene (rs2277698) according to the codominant inheritance model. We found no associations of polymorphic variants in the MMP1 (rs514921), MMP3 (rs626750), MMP9 (rs17576) and TIMP2 (rs2277698) genes with the serum blood level of MMP, as well as their inhibitors. Four-loci model of gene-gene interactions (MMP9 (rs17576) – MMP3 (rs626750) – MMP1 (rs514921) – TIMP2 (rs2277698)) characterized by high sensitivity, specificity and risk effect to the coronary artery disease with concomitant metabolic syndrome development was discovered. Conclusion: This study revealed the association of polymorphic variants in the MMP genes and their inhibitors with the risk of coronary artery disease with concomitant metabolic syndrome. In addition, a four-locus model of intergenic interactions with high sensitivity and specificity was obtained.

FANCD2 counteracts O6-methylguanine-induced mismatch repair-dependent apoptosis.

Sn1-type alkylating agents methylate the oxygen atom on guanine bases thereby producing O6-methylguanine. This modified base could pair with thymine and cytosine, resulting in the formation of O6-methylguanine/thymine mismatch during DNA replication, recognized by the mismatch repair (MMR) complex, which then initiates the DNA damage response and subsequent apoptotic processes. In our investigation of the molecular mechanisms underlying MMR-dependent apoptosis, we observed FANCD2 modification upon the activity of alkylating agent N-methyl-N-nitrosourea (MNU). This observation led us to hypothesize a relevant role for FANCD2 in the apoptosis induction process. We generated FANCD2 knockout cells using the CRISPR/Cas9 method in the human cervical cancer cell line HeLa MR. FANCD2-deficient cells exhibited MNU hypersensitivity. Upon MNU exposure, FANCD2 colocalized with the MMR complex. MNU-treated FANCD2 knockout cells displayed severe S phase delay followed by increased G2/M arrest and MMR-dependent apoptotic cell death. Moreover, FANCD2 knockout cells exhibited impaired CtIP and RAD51 recruitment to the damaged chromatin and DNA double-strand break accumulation, indicated by simultaneously observed increased γH2AX signal and 53BP1 foci. Our data suggest that FANCD2 is crucial for recruiting homologous recombination factors to the sites of the MMR-dependent replication stress to resolve the arrested replication fork and counteract O6-methylguanine-triggered MMR-dependent apoptosis.

Bloom syndrome DNA helicase mitigates mismatch repair-dependent apoptosis

Generation of O6-methylguanine (O6-meG) by DNA-alkylating agents such as N-methyl N-nitrosourea (MNU) activates the multiprotein mismatch repair (MMR) complex and the checkpoint response involving ATR/CHK1 and ATM/CHK2 kinases, which may in turn trigger cell cycle arrest and apoptosis. The Bloom syndrome DNA helicase BLM interacts with the MMR complex, suggesting functional relevance to repair and checkpoint responses. We observed a strong interaction of BLM with MMR proteins in HeLa cells upon treatment with MNU as evidenced by co-immunoprecipitation as well as colocalization in the nucleus as revealed by dual immunofluorescence staining. Knockout of BLM sensitized HeLa MR cells to MNU-induced cell cycle disruption and enhanced expression of the apoptosis markers cleaved caspase-9 and PARP1. MNU-treated BLM-deficient cells also exhibited a greater number of 53BP1 foci and greater phosphorylation levels of H2AX at S139 and RPA32 at S8, indicating the accumulation of DNA double-strand breaks. These findings suggest that BLM prevents double-strand DNA breaks during the MMR-dependent DNA damage response and mitigates O6-meG-induced apoptosis.

Arrhythmic mitral valve prolapse with versus without prior mitral valve repair: clinical profiles, electrophysiological substrates, and long-term clinical outcomes

Abstract Background Arrhythmic mitral valve prolapse (AMVP) is characterized by an arrhythmogenic left ventricular substrate, with high prevalence of myocardial scar. Whether patients with prior mitral valve repair for mitral valve prolapse (MVP) and new-onset complex ventricular arrhythmias (VAs) after cardiac surgery have different electroanatomical substrate and arrhythmic outcomes compared with AMVP patients without prior mitral valve surgery is currently unknown. Purpose We sought to compare the electroanatomical substrate and long-term clinical outcomes of patients with new-onset complex VAs after mitral valve surgery to AMVP patients without prior surgery. Methods We conducted a multicenter, prospective, observational study, enrolling MVP patients with prior mitral valve repair and new-onset complex VAs (&amp;gt;1000 premature ventricular contractions [PVCs]/day, nonsustained ventricular tachycardia [NSVT], and sustained VT) after cardiac surgery (group A,n=9), and patients with MVP, complex VAs and no prior surgery (group B,n=20). Each patient underwent a comprehensive diagnostic workup, including left ventricular electroanatomical mapping. Clinical-imaging data, as well as the location and segmental extension of both low-voltage areas and late potentials were assessed and compared between the two groups. The primary outcome was the occurrence of sustained VT or ventricular fibrillation(VF) during follow-up. Results In group A, complex VAs were first diagnosed after a median of 30(8-56) months following mitral valve repair. The characteristics of patients from the two study groups are presented in the Table. Patients from group A were older, sustained VT was nonsignificantly more common at baseline, the PVC count nonsignificantly higher, and LVEF nonsignificantly lower. Mitral annular disjunction was never observed in group A, while it was found in 7 patients from group B (p=0.066). At LV electroanatomical voltage mapping, bipolar and unipolar low-voltage areas (LVAs) were equally common in the two groups overall, and typically involved basal perimitral regions. However, patients from group B had concomitant bipolar and unipolar LVAs 50% of times, with larger unipolar LVAs, while patients from group A mostly showed isolated bipolar LVAs. Over a median follow-up of 15 (12-41) months, patients from group A (n=3, 33%) had slightly higher incidence of sustained VT or VF (HR: 1.91; 95% CI, 1.06-42.65; log-rank p=0.02, Figure) than patients from group B (n=2, 10%). Conclusion Compared to patients with AMVP and no prior cardiac surgery, patients with new-onset complex VAs after mitral valve repair for MVP have a slightly different clinical profile and electroanatomical substrate, characterized by predominant bipolar LVAs in the perimitral region. The long-term risk of major ventricular arrhythmias appears slightly higher in MVP patients with prior mitral valve surgery, mandating at least an equally careful risk assessment in both groups.

The impact of developmental stage, tissue type, and sex on DNA double-strand break repair in Drosophila melanogaster.

Accurate repair of DNA double-strand breaks (DSBs) is essential for the maintenance of genome integrity, as failure to repair DSBs can result in cell death. The cell has evolved two main mechanisms for DSB repair: non-homologous end-joining (NHEJ) and homology-directed repair (HDR), which includes single-strand annealing (SSA) and homologous recombination (HR). While certain factors like age and state of the chromatin are known to influence DSB repair pathway choice, the roles of developmental stage, tissue type, and sex have yet to be elucidated in multicellular organisms. To examine the influence of these factors, DSB repair in various embryonic developmental stages, larva, and adult tissues in Drosophila melanogaster was analyzed through molecular analysis of the DR-white assay using Tracking across Indels by DEcomposition (TIDE). The proportion of HR repair was highest in tissues that maintain the canonical (G1/S/G2/M) cell cycle and suppressed in both terminally differentiated and polyploid tissues. To determine the impact of sex on repair pathway choice, repair in different tissues in both males and females was analyzed. When molecularly examining tissues containing mostly somatic cells, males and females demonstrated similar proportions of HR and NHEJ. However, when DSB repair was analyzed in male and female premeiotic germline cells utilizing phenotypic analysis of the DR-white assay, there was a significant decrease in HR in females compared to males. This study describes the impact of development, tissue-specific cycling profile, and, in some cases, sex on DSB repair outcomes, underscoring the complexity of repair in multicellular organisms.

Impact of surgeon volume, experience, and training on outcomes after arthroscopic rotator cuff repair: a nationwide analysis of 1489 surgeons

BackgroundGiven the complexity of arthroscopic rotator cuff repair (ARCR) and increasing prevalence, there is a need for comprehensive, large-scale studies that investigate potential correlations between surgeon-specific factors and postoperative outcomes after ARCR. This study examines how surgeon-specific factors including case volume, career length, fellowship training, practice setting, and regional practice impact two-year reoperation rates, conversion to total shoulder arthroplasty (anatomic or reverse) (TSA), and 90-day post-ARCR hospitalization. MethodsThe PearlDiver Mariner Database was used to collect surgeon-specific variables and query patients who underwent ARCR from 2015 to 2018. Patient outcomes were tracked for two years, including reoperations, hospitalizations, and ICD-10 codes for revision rotator cuff repair (RCR) laterality. Hospitalizations were defined as any emergency department (ED) visit or hospital readmission within 90 days after primary ARCR. Surgeon-specific factors including surgeon case volume, career length, fellowship training, practice setting, and regional practice were analyzed in relation to postoperative outcomes using both univariate and multivariate logistic regression. Results94,150 patients underwent ARCR by 1,489 surgeons. On multivariate analysis, high volume surgeons demonstrated a higher risk for two-year total reoperation (OR = 1.06, 95% CI: 1.01-1.12, P = 0.03) and revision RCR (OR = 1.06, 95% CI: 1.01-1.12, P = 0.02) compared to low volume surgeons. Early-career surgeons showed higher rates of 90-day ED visits (mid-career surgeons: OR = 0.78, 95% CI: 0.73-0.83, P < 0.001; late-career surgeons: OR = 0.73, 95% CI: 0.68-0.78, P < 0.001) and hospital readmission (mid-career surgeons: OR = 0.74, 95% CI: 0.63-0.87, P < 0.001; late-career surgeons: OR = 0.73, 95% CI: 0.61-0.88, P = 0.006) compared to mid- and late-career surgeons. Sports Medicine and/or Shoulder and Elbow fellowship-trained surgeons demonstrated lower two-year reoperation risk (OR = 0.95, CI: 0.91-0.99, P = 0.04) and fewer 90-day ED visits (OR = 0.93, 95% CI = 0.88-0.98, P = 0.002). Academic surgeons experienced higher readmission rates compared to community surgeons (OR = 1.16, 95% CI = 1.01-1.34, P = 0.03). Surgeons practicing in the Northeast demonstrated lower two-year reoperation (OR = 0.88, 95% CI: 0.83-0.93, P < 0.001) and revision (OR = 0.88, 95% CI: 0.83-0.94, P < 0.001) rotator cuff repair risk, compared to surgeons in the Southern United States. ConclusionsHigh-volume surgeons exhibit higher two-year reoperation rates after ARCR compared to low-volume surgeons. Early-career surgeons demonstrate increased hospitalizations. Sports Medicine or Shoulder and Elbow Surgery fellowships correlate with reduced two-year reoperation rates and 90-day ED visits.