Characterisation of the mechano-chemical relationship between actin and microtubule cytoskeletons and the active motion of cytoplasmic components

The advancements in imaging techniques have markedly enhanced the ability to observe and reconstruct dynamic cellular processes, thereby deepening our understanding of cell behaviour. This study's primary objective is to probe the intricate dynamics influencing organelle motion within the Drosophila melanogaster oocyte, aiming to unravel the nuanced mechanochemical relationship between cytoskeletal networks and organelle dynamics, and the forces governing organelle motion in the cell. Utilizing a combination of confocal microscopy, differential dynamic microscopy and single particle tracking, this research explores the reciprocal relationship between actin and microtubules and their impact on the morphology, motion, and distribution of endosomes and mitochondria in the oocyte. The findings underscore a tightly interconnected system involving organelle dynamics and cytoskeletal function for proper distribution, morphology, and transport of organelles. Notably, this intricate orchestration suggests that susceptibility to certain types of motion and modes of transport extends beyond the physical characteristics of the cytoplasm and the mechanisms generating force in that environment. Instead, it is significantly shaped by the dynamic interplay with other cellular components, subtly influencing their mutual functions. The results reveal variations in advective and diffusive rates among organelle populations, with Rab5-positive early endosomes and mitochondria exhibiting the highest and most consistent advective motion, while Rab7-positive late endosomes display higher diffusive rates. The study also sheds light on the influence of mitochondrial dynamics and morphology on the motility of other organelles, namely endosomes. This investigation carries broader implications for disease research, drawing parallels with abnormal mitochondrial morphologies found in neuropathies and neurodegeneration. In essence, this research contributes to unravelling the intricate mechanisms governing organelle motion, adding to the foundational understanding of biophysical principles influencing cellular processes

Lupus Anticoagulunt Associated with Transient Severe Factor X Deficiency: A Report of Two Patients Presenting with Major Bleeding Complications

Abstract Acquired factor X (FX) deficiency is rare, but has been reported in diverse disease states, including systemic amyloidosis and respiratory infections. FX deficiency associated with lupus anticoagulant (LA) and a bleeding diathesis has not been previously reported. We report two patients both of whom presented with a severe bleeding diathesis after a preceding respiratory infection due to isolated FX deficiency associated with a LA. The FX deficiency and LA were transient. We conclude that patients with LA may rarely present with severe acquired FX deficiency. This may be another mechanism whereby patients with antiphospholipid antibodies present with bleeding complications

Using Artificial Neural Networks to Predict Intra-Abdominal Abscess Risk Post-Appendectomy

OBJECTIVE: To determine if artificial neural networks (ANN) could predict the risk of intra-abdominal abscess (IAA) development post-appendectomy. BACKGROUND: IAA formation occurs in 13.6% to 14.6% of appendicitis cases with complicated appendicitis as the most common cause of IAA. There remains inconsistency in describing the severity of appendicitis with variation in treatment with respect to perforated appendicitis. METHODS: Two reproducible ANN with different architectures were developed on demographic, clinical, and surgical information from a retrospective surgical dataset of 1574 patients less than 19 years old classified as either negative (n = 1,328) or positive (n = 246) for IAA post-appendectomy for appendicitis. Of 34 independent variables initially, 12 variables with the highest influence on the outcome selected for the final dataset for ANN model training and testing. RESULTS: A total of 1574 patients were used for training and test sets (80%/20% split). Model 1 achieved accuracy of 89.84%, sensitivity of 70%, and specificity of 93.61% on the test set. Model 2 achieved accuracy of 84.13%, sensitivity of 81.63%, and specificity of 84.6%. CONCLUSIONS: ANN applied to selected variables can accurately predict patients who will have IAA post-appendectomy. Our reproducible and explainable ANNs potentially represent a state-of-the-art method for optimizing post-appendectomy care

Optical flow analysis reveals that Kinesin-mediated advection impacts on the orientation of microtubules in the Drosophila oocyte.

The orientation of microtubule networks is exploited by motors to deliver cargoes to specific intracellular destinations, and is thus essential for cell polarity and function. Reconstituted in vitro systems have largely contributed to understanding the molecular framework regulating the behavior of microtubule filaments. In cells however, microtubules are exposed to various biomechanical forces that might impact on their orientation, but little is known about it. Oocytes, which display forceful cytoplasmic streaming, are excellent model systems to study the impact of motion forces on cytoskeletons in vivo. Here we implement variational optical flow analysis as a new approach to analyze the polarity of microtubules in the Drosophila oocyte, a cell that displays distinct Kinesin-dependent streaming. After validating the method as robust for describing microtubule orientation from confocal movies, we find that increasing the speed of flows results in aberrant plus end growth direction. Furthermore, we find that in oocytes where Kinesin is unable to induce cytoplasmic streaming, the growth direction of microtubule plus ends is also altered. These findings lead us to propose that cytoplasmic streaming - and thus motion by advection - contributes to the correct orientation of MTs in vivo. Finally, we propose a possible mechanism for a specialised cytoplasmic actin network (the actin mesh) to act as a regulator of flow speeds; to counteract the recruitment of Kinesin to microtubules. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

Sudden cardiac death in patients with ischemic heart failure undergoing coronary artery bypass grafting results from the STICH randomized clinical trial (Surgical Treatment for Ischemic Heart Failure)

Background—The risk of sudden cardiac death (SCD) in patients with heart failure following CABG has not been examined in a contemporary clinical trial of surgical revascularization. This analysis describes the incidence, timing and clinical predictors of SCD after CABG. Methods—Patients enrolled in the Surgical Treatment of Ischemic Heart Failure (STICH) trial who underwent CABG with or without surgical ventricular reconstruction (SVR) were included. We excluded patients with prior ICD and those randomized only to medical therapy. The primary outcome was SCD as adjudicated by a blinded committee. A Cox model was used to examine and identify predictors of SCD. The Fine and Gray method was used to estimate the incidence of SCD accounting for the competing risk of other deaths. Results—Over a median follow-up of 46 months, 113 patients of 1411 patients who received CABG without (n = 934) or with SVR (n = 477) had SCD; 311 died of other causes. The mean LVEF at enrollment was 28±9%. The 5-year cumulative incidence of SCD was 8.5%. Patients who had SCD and those who did not die were younger and had fewer comorbid conditions than those who died for reasons other than SCD. In the first 30 days after CABG, SCD (n=5) accounted for 7% of all deaths. The numerically greatest monthly rate of SCD was in the 31-90 day time period. In a multivariable analysis including baseline demographics, risk factors, coronary anatomy and LV function, ESVI and BNP were most strongly associated with SCD. Conclusions—The monthly risk of SCD shortly after CABG among patients with a low LVEF is highest between the first and third month, suggesting that risk stratification for SCD should occur early in the postoperative period, particularly in patients with increased preoperative ESVI and/or BNP

Sex Differences in Left Ventricular Electrical Dyssynchrony and Outcomes with Cardiac Resynchronization Therapy

BACKGROUND: Women seem to derive more benefit from cardiac resynchronization therapy (CRT) than men, even after accounting for the higher burden of risk factors for nonresponse often observed in men. OBJECTIVE: To assess for sex-specific differences in left ventricular (LV) electrical dyssynchrony as a contributing electrophysiological explanation for the greater degree of CRT benefit among women. METHODS: We compared the extent of baseline LV electrical dyssynchrony, as measured by the QRS area (QRSA), among men and women with left bundle branch block (LBBB) undergoing CRT at Duke University (n = 492, 35% women) overall and in relation to baseline QRS characteristics using independent sample t tests and Pearson correlation coefficients. Cox regression analyses were used to relate sex, QRSA, and QRS characteristics to the risk of cardiac transplantation, LV assist device implant, or death. RESULTS: Although the mean QRS duration (QRSd) did not differ by sex, QRSA was greater for women vs men (113.8 μVs vs 98.2 μVs, P < .001), owing to differences in the QRSd <150 ms subgroup (92.3 ± 28.7 μVs vs 67.6 ± 26.2 μVs, P < .001). Among those with nonstrict LBBB, mean QRSd was similar but QRSA was significantly greater among women than men (96.0 ± 25.0 μVs vs 63.6 ± 26.2 μVs, P < .001). QRSA was similar among men and women with strict LBBB (P = .533). Female sex was associated with better long-term outcomes in an unadjusted model (hazard ratio 0.623, confidence interval 0.454–0.857, P = .004) but sex no longer predicted outcomes after accounting for differences in QRSA. CONCLUSIONS: Our study suggests that sex-specific differences in LV dyssynchrony contribute to greater CRT benefit among women. Standard QRSd and morphology assessments seem to underestimate the extent of LV electrical dyssynchrony among women with LBBB

Assessment of the quality of existing patient educational tools focused on sudden cardiac arrest: a systematic evaluation by the Sudden Cardiac Arrest Thought Leadership Alliance

Background Conveying contemporary treatment options for those at risk of sudden cardiac arrest (SCA) is challenging. The purpose of the present research was to evaluate the quality and usability of available patient educational tools relevant to SCA and its treatment options, such as implantable cardioverter defibrillators (ICDs). We hypothesized that this review would identify gaps in areas of information for the enhancement of patient education and decision-making materials. Methods We used a formal instrument to assess specific domains of content, development, and effectiveness of 18 available SCA and ICD educational tools. The multidisciplinary review panel included two electrophysiologists, two general cardiologists, a cardiac psychologist, a health services researcher, and a patient advocate. Results Of the 18 education tools, four were rated as “good, may need revisions, but sufficient for use�, 12 were rated as “marginal, needs revision prior to use�, and two were rated as “poor, inadequate for use�. None of the tools were rated as being of “very good� or “excellent� quality. Conclusion There appear to be opportunities to improve the quality and completeness of existing educational tools for patients with SCA and ICD. While many tools have been developed, they fall below current standards for supporting informed medical decision-making