This study consists of a retrospective cohort study, a systematic review, and a meta-analysis which were separately conducted. This study aimed to investigate the prevalence of atlas arch defects, generate an evidence-based synthesis, and propose a common classification system for the anterior and combined atlas arch defects. Atlas arch defects are well-corticated gaps in the anterior or posterior arch of the atlas. When both arches are involved, it is known as a combined arch defect. Awareness of these defects is essential for avoiding complications during surgical procedures on the upper spine. The prevalence of arch defects was investigated in an open-access OPC-Radiomics (Radiomic Biomarkers in Oropharyngeal Carcinoma) dataset comprising 606 head and neck computed tomography scans from oropharyngeal cancer patients. A systematic review and meta-analysis were performed to generate prevalence estimates of atlas arch defects and propose a classification system for the anterior and combined atlas arch defects. The posterior arch defect was found in 20 patients (3.3%) out of the 606 patients investigated. The anterior arch defect was not observed in any patient, while a combined arch defect was observed in one patient (0.2%). A meta-analysis of 13,539 participants from 14 studies, including the present study, yielded a pooled-posterior arch defect prevalence of 2.07% (95% confidence interval [CI], 1.22%–2.92%). The prevalences of anterior and combined arch defects were 0.00% (95% CI, 0.00%–0.10%) and 0.14% (95% CI, 0.04%–0.25%), respectively. The anterior and combined arch defects were classified into five subtypes based on their morphology and frequency. The present study showed that atlas arch defects were present in approximately 2% of the general population. For future studies, larger sample sizes should be used for studying arch defects to avoid the small-study effect and to predict the prevalence accurately.

Considerable controversy has surrounded the functional anatomy of the cytoskeleton of the contractile vascular smooth muscle cell. Recent studies have suggested a dynamic nature of the cortical cytoskeleton of these cells, but direct proof has been lacking. Here, we review past studies in this area suggesting a plasticity of smooth muscle cells. We also present images testing these suggestions by using the technique of immunoelectron microscopy of metal replicas to directly visualize the cortical actin cytoskeleton of the contractile smooth muscle cell along with interactions by representative cytoskeletal binding proteins. We find the cortical cytoskeletal matrix to be a branched, interconnected network of linear actin bundles. Here, the focal adhesion proteins talin and zyxin were localized with nanometer accuracy. Talin is reported in past studies to span the integrin–cytoplasm distance in fibroblasts and zyxin is known to be an adaptor protein between alpha-actinin and VASP. In response to activation of signal transduction with the alpha-agonist phenylephrine, we found that no movement of talin was detectable but that the zyxin-zyxin spacing was statistically significantly decreased in the smooth muscle cells examined. Contractile smooth muscle is often assumed to have a fixed cytoskeletal structure. Thus, the results included here are important in that they directly support the concept at the electron microscopic level that the focal adhesion of the contractile smooth muscle cell has a dynamic nature and that the protein–protein interfaces showing plasticity are protein-specific.

Background and Objectives: Pancreas divisum (PD) is the most common congenital anomaly of the pancreatic ductal system and has been suggested to contribute to pancreatic pathology. However, its true prevalence and relationship with pancreatic diseases remain debated. This systematic review and meta-analysis aimed to estimate the global prevalence of PD and evaluate its association with pancreatic disease. Materials and Methods: A comprehensive search of Google Scholar, Scopus, and PubMed was conducted to identify studies reporting the prevalence of PD across all populations and diagnostic modalities. Pooled prevalence estimates were calculated using a random-effects model. Between-study heterogeneity was assessed using the I² statistic, and publication bias was evaluated using Egger’s test. Results: A total of 117 studies comprising 193,672 subjects were included. The pooled global prevalence of PD was 11.1% (95% CI: 8.0–14.2%) with substantial heterogeneity (I² = 99.96%). PD prevalence was higher among individuals with pancreatic disease (18.7%) compared with cadaveric/autopsy studies (8.8%), healthy individuals (5.6%), and consecutive patients (4.7%). Both complete and incomplete PD were more common in subjects with pancreatic diseases. Among PD subtypes, type I was the most prevalent. Egger’s test demonstrated significant publication bias (p < 0.01). Conclusions: PD affects approximately one in ten individuals worldwide and appears more prevalent in patients with pancreatic diseases. However, this finding should be interpreted with caution due to potential selection bias from predominantly ERCP-based studies.