PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al

Biomechanical effects of rapid maxillary expansion on the craniofacial skeleton, studied by the finite element method

The aim of this study was to evaluate the biomechanical effect of rapid maxillary expansion (RME) on the craniofacial complex by using a three-dimensional finite element model (FEM) of the craniofacial skeleton. The construction of the three-dimensional FEM was based on computer tomography (CT) scans of the skull of a 12-year-old male subject. The CT pictures were digitized and converted to the finite element model by means of a procedure developed for the present study. The final mesh consisted of 2270 thick shell elements with 2120 nodes. The mechanical response in terms of displacement and von Mises stresses was determined by expanding the maxilla up to 5 mm on both sides. Viewed occlusally, the two halves of the maxilla were separated almost in a parallel manner during 1-, 3-, and 5-mm expansions. The greatest widening was observed in the dento-alveolar areas, and gradually decreased through the superior structures. The width of the nasal cavity at the floor of the nose increased markedly. However, the postero-superior part of the nasal cavity was moved slightly medially. No displacement was observed in the parietal, frontal and occipital bones. High stress levels were observed in the canine and molar regions of the maxilla, lateral wall of the inferior nasal cavity, zygomatic and nasal bones, with the highest stress concentration at the pterygoid plates of the sphenoid bone in the region close to the cranial base

Outcome of Very Low and Low Birth Weight Infants with Esophageal Atresia: Results of the Turkish Esophageal Atresia Registry

Introduction The data of the Turkish Esophageal Atresia Registry (TEAR) was evaluated to define the outcome of very low birth weight (VLBW) and low BW (LWB) infants with esophageal atresia (EA). Materials and Methods The data registered by 24 centers between 2014 and 2018 were evaluated for demographic features, prenatal findings, associated anomalies, surgical treatment, and outcome. Patients were enrolled in three groups according to their BWs (VLBW 1,500g), LWB=1,500-2,500g), and normal BW (NBW; >2,500g). Results Among the 389 cases, there were 37 patients (9.5%) in the VLBW group, 165 patients (42.4%) in the LBW group, and 187 patients (48.1%) in the NBW group. Prenatal diagnosis rates were similar among the three groups (29.7, 34.5, and 24.6%, respectively). The standard primary anastomosis was achieved at a significantly higher rate in NWB cases than in the other groups ( p 0.05). In patients with tracheoesophageal fistula (TEF), patients of the NBW group had significantly higher rates of full oral feedings, when compared with VLBW and LBW cases ( p 0.05). At the end of the first year, when we evaluate all patients, the number of cases with fistula recanalization and esophageal anastomotic strictures (AS) requiring esophageal dilatation was similar among the groups. The weight and height measurements at 6 months and 1 year of age of the survivors were similar in all the groups. The overall mortality rate was significantly higher in the VLBW and LBW groups, when compared with the NBW patients, even in patients with tension-free anastomosis ( p 0.05). The incidence of the associated anomalies was 90.6% in cases with mortality, which was significantly higher than in survivors (59.6%; p 0.05). According to Spitz's classification, the survival rate was 87.1% in class I, 55.3% in class II, and 16.7% in class III. The most common causes of mortality were associated with cardiovascular diseases, pneumonia, and sepsis. Conclusion The national data of TEAR demonstrates that the developmental and feeding parameters are better in NBW patients. Although VLBW patients have higher risk of developing fistula canalization than the LBW and NBW groups, long-term complications, such as anastomotic strictures, weight, and height values, after 1 year are similar in both groups. According to our results, associated anomalies and LBWs are still significant risk factors for mortality in cases with EA

Arginine vasopressin in cerebrospinal fluid is a marker of sociality in nonhuman primates

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by core social impairments. ASD remains poorly understood because of the difficulty in studying disease biology directly in patients and the reliance on mouse models that lack clinically relevant, complex social cognition abilities. We use ethological observations in rhesus macaques to identify male monkeys with naturally occurring low sociality. These monkeys showed differences in specific neuropeptide and kinase signaling pathways compared to socially competent male monkeys. Using a discovery and replication design, we identified arginine vasopressin (AVP) in cerebrospinal fluid (CSF) as a key marker of group differences in monkey sociality; we replicated these findings in an independent monkey cohort. We also confirmed in an additional monkey cohort that AVP concentration in CSF is a stable traitlike measure. Next, we showed in a small pediatric cohort that CSF AVP concentrations were lower in male children with ASD compared to age-matched male children without ASD (but with other medical conditions). We demonstrated that CSF AVP concentration was sufficient to accurately distinguish ASD cases from medical controls. These data suggest that AVP and its signaling pathway warrant consideration in future research studies investigating new targets for diagnostics and drug development in ASD. © 2018 The Authors