Bistrand lesions embedded within a single helical turn of tridecameric deoxyoligonucleotide duplexes represent a model system for exploring the impact of clustered lesions that occur in vivo and pose a significant challenge to cellular repair machineries. Such investigations are essential for understanding the forces that dictate lesion‐induced mutagenesis, carcinogenesis, and cytotoxicity within a context that mimics local helical perturbations caused by an ionizing radiation event. This study characterizes the structural and energy profiles of DNA duplexes harboring synthetic abasic sites (tetrahydrofuran, F) as models of clustered bistrand abasic (AP) lesions. The standard tridecameric dGCGTACCCATGCG·dCGCATGGGTACGC duplex is employed to investigate the energetic impact of single and bistrand AP sites by strategically replacing one or two bases within the central CCC/GGG triplet. Our combined analysis of temperature‐dependent UV and circular dichroism (CD) profiles reveals that the proximity and relative orientation of AP sites within bistrand‐damaged duplexes imparts a significant thermodynamic impact. Specifically, 3′‐staggered lesions (CCF/GFG) exert a greater destabilizing effect when compared with their 5′‐counterpart (FCC/GFG). Moreover, a duplex harboring the central bistrand AP lesion (CFC/GFG) is moderately destabilized yet exhibits distinct properties relative to both the 3′ and 5′‐orientations. Collectively, our energetic data are consistent with structural studies on bistrand AP‐duplexes of similar sequence in which a 3′‐staggered lesion exerts the greatest perturbation, a finding that provides significant insight regarding the impact of orientation on lesion repair processing efficiency.
Portal vein aneurysms are rare vascular malformations with unclear etiologies and optimal treatment guidelines. Although Doppler ultrasonography is the most commonly used diagnostic tool, there is no gold standard imaging modality. Despite recommendations of surgical treatment for symptomatic aneurysms, there are limited options in the management of portal vein aneurysm-related complications in patients unfit for surgical intervention. We describe an 85-year-old man who presented with abdominal pain and low-grade fever with clinical signs consistent with cholangitis. Endoscopic retrograde cholangiopancreatography revealed a common hepatic duct stricture and concomitant intraductal ultrasonography identified adjacent aneurysmal portal vein dilatation. The final diagnosis of portal vein aneurysm was made using contrast computerized tomography scan. The patient was considered unsuitable for surgery due to his advanced age and multiple comorbidities. Instead, an endoscopic biliary plastic stent was inserted as a therapeutic alternative, which successfully achieved complete resolution of symptoms 3 days after the procedure. The patient was regularly followed at the outpatient clinic with repeated stent replacements every 3 to 4 months. After a follow-up of over 3.5 years, the patient remained symptom-free without signs of portal vein aneurysm compression. The result suggests that repeated stent replacements may be a therapeutic option for biliary compression by portal vein aneurysm in patients contraindicated for surgical intervention.
Purpose To compare the performance of non-contrast MRI with HASTE versus contrast-enhanced MRI/3D-MRCP for assessment of suspected choledocholithiasis in hospitalized patients. Methods and Materials 123 contrast-enhanced abdominal MRI/MRCP scans in the hospital setting for possible choledocholithiasis were retrospectively evaluated. ERCP, intraoperative cholangiogram or documented clinical resolution served as the reference standard. Readers first evaluated the biliary tree using coronal and axial HASTE and other non-contrast sequences, and later reviewed the entire exam with post-contrast sequences and 3D-MRCP. Test performance for the image sets was compared for choledocholithiasis, acute hepatitis, cholangitis, and acute cholecystitis. Reader agreement, MRCP image quality, and confidence levels were also assessed. Clinical predictors of age and fever were tested for association with perceived need for contrast in biliary assessment. Results There were 27 cases of choledocholithiasis, 31 cases of acute hepatitis, 37 cases of acute cholecystitis, and 3 clinically diagnosed cases of acute cholangitis. Both the abbreviated and full contrast-enhanced/MRCP image sets resulted in high accuracy for choledocholithiasis (91.1–94.3% versus 91.9–92.7%). There was no difference in sensitivity or specificity for either reader for any diagnosis between image sets (p>0.40). 1 reader showed improved confidence (p<0.001) with inclusion of MRCP and contrast-enhanced images, but neither confidence nor MRCP quality scores were associated with diagnostic accuracy. Patient age and fever did not predict the need for contrast-enhanced images. Conclusion In hospitalized patients with suspected choledocholithiasis, performance of non-contrast abdominal MRI with HASTE is similar to contrast-enhanced MRI with 3D-MRCP, offering potential for decreased scanning time and improved patient tolerability.
Minimally invasive surgery has made a profound impact on how urologists approach the challenges in reconstruction of the urinary tract. The advent of laparoscopic approaches to reconstructive urology have demonstrated comparable outcomes to open surgery with improved morbidity. The recent adoption of robotic surgery has seen further advancements such as improved visibility and, freedom of movement, and an easier technical learning curve. With these advantages, more reconstructive urology procedures are being performed robotically. Herein, we review reconstructive urology procedures for which robotics have been applied.
Mammography is considered the gold standard for breast cancer screening. Multiple risk factors that affect breast cancer development have been identified; however, there is an ongoing debate regarding the significance of these factors. Machine learning (ML) models and Shapley Additive Explanation (SHAP) methodology can rank risk factors and provide explanatory model results. This study used ML algorithms with SHAP to analyze the risk factors between two different age groups and evaluate the impact of each factor in predicting positive mammography. The ML model was built using data from the risk factor questionnaires of women participating in a breast cancer screening program from 2017 to 2021. Three ML models, least absolute shrinkage and selection operator (lasso) logistic regression, extreme gradient boosting (XGBoost), and random forest (RF), were applied. RF generated the best performance. The SHAP values were then applied to the RF model for further analysis. The model identified age at menarche, education level, parity, breast self-examination, and BMI as the top five significant risk factors affecting mammography outcomes. The differences between age groups ranked by reproductive lifespan and BMI were higher in the younger and older age groups, respectively. The use of SHAP frameworks allows us to understand the relationships between risk factors and generate individualized risk factor rankings. This study provides avenues for further research and individualized medicine.
Gastric hemangiomas (GHs) are extremely rare vascular lesions of mesodermal origin that may occur in isolation or in conjunction with underlying congenital pathology. Due to the scarcity of these tumors, there is no standardized diagnostic method; however, many have found the combination of endoscopic investigation and radiographic imaging to be most effective, with the presence of phleboliths on computerized tomography as being pathognomonic for GHs. Surgical treatment for symptomatic lesions is curative with no reports of recurrence. We describe a 21-year-old woman who presented with epigastric pain and one episode of 250 mL hematemesis earlier that morning. Under the impression of an upper gastrointestinal bleed due to peptic ulcer disease, esophagogastroduodenoscopy was performed which revealed a 5-cm blood clot-like mass similar in appearance to that of a II-b peptic ulcer, but the presence of a bridging fold led to the suspicion of a possible submucosal tumor. Dynamic computerized tomography scan showed similar findings, and the patient was referred for surgical intervention. Laparoscopic distal gastrectomy was performed with the final diagnosis of cavernous GH made via histological evaluation. The patient was discharged 9 days later with no complications. This case puts emphasis on the importance of considering cavernous GH as a potential cause of severe upper GI bleeding especially in those with atypical demographic profile and history.
CONCLUSIONS: RYVBNR with a Y-V plasty is a feasible, and effective technique for managing the difficult reconstructive problem of recalcitrant BNC.
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