Growth hormone deficiency in megalencephaly-capillary malformation syndrome: An association with activating mutations in PIK3CA

Megalencephaly-capillary malformation syndrome (MCAP) is a brain overgrowth disorder characterized by cortical malformations (specifically polymicrogyria), vascular anomalies, and segmental overgrowth secondary to somatic activating mutations in the PI3K-AKT-MTOR pathway (PIK3CA). Cases of growth failure and hypoglycemia have been reported in patients with MCAP, raising the suspicion for unappreciated growth hormone (GH) deficiency. Here we report an observational multicenter study of children with MCAP and GH deficiency. Eleven participants were confirmed to have GH deficiency, all with very low or undetectable circulating concentrations of insulin-like growth factor-1 and insulin-like growth factor binding protein-3. Seven underwent GH stimulation testing and all had insufficient responses with a median GH peak of 3.7 ng/ml (range 1.1-8.6). Growth patterns revealed a drastic decline in length z-scores within the first year of life but then stabilized afterward. Five were treated with GH; one discontinued due to inconsolability. The other four participants continued on GH with improvement in linear growth velocity. Other endocrinopathies were identified in 7 of the 11 participants in this cohort. This study indicates that GH deficiency is associated with MCAP and that children with MCAP and hypoglycemia and/or postnatal growth failure should be evaluated for GH deficiency and other endocrinopathies

Impact of Stomatal Density and Morphology on Water-Use Efficiency in a Changing World

Global warming and associated precipitation changes will negatively impact on many agricultural ecosystems. Major food production areas are expected to experience reduced water availability and increased frequency of drought over the coming decades. In affected areas, this is expected to reduce the production of important food crops including wheat, rice, and maize. The development of crop varieties able to sustain or improve yields with less water input is, therefore, a priority for crop research. Almost all water used for plant growth is lost to the atmosphere by transpiration through stomatal pores on the leaf epidermis. By altering stomatal pore apertures, plants are able to optimize their CO2 uptake for photosynthesis while minimizing water loss. Over longer periods, stomatal development may also be adjusted, with stomatal size and density being adapted to suit the prevailing conditions. Several approaches to improve drought tolerance and water-use efficiency through the modification of stomatal traits have been tested in the model plant Arabidopsis thaliana. However, there is surprisingly little known about the stomata of crop species. Here, we review the current understanding of how stomatal number and morphology are involved in regulating water-use efficiency. Moreover, we discuss the potential and limitations of manipulating stomatal development to increase drought tolerance and to reduce water loss in crops as the climate changes

Impact of Personal, Familial, and Socioeconomic Factors on the Return of Remotely Collected Samples for Genetic Testing

There are a multitude of barriers known to impact access to medical care in the United States. COVID-19 has changed and compounded these barriers and led to a shift in the setting of the genetic counseling (GC) appointment, and in sample types used for genetic testing, specifically with use of telemedicine and remotely collected saliva kits. Previous studies have described lack of patient follow-through in returning these kits. Though the understanding of barriers to medical care, including access to genetics services, is well described, there is little in the literature for how these barriers impact the return of remotely collected saliva kits for genetic testing. This retrospective chart review of two hospital systems in Houston, Texas, one a specialty hospital and one a safety-net hospital, obtained personal and familial health, demographic, and socioeconomic information on 326 individuals who consented to hereditary cancer genetic testing and were sent a saliva collection kit for remote sample collection. The overall rate of saliva kit return was 84.3%. Non-White patients were less likely to return saliva kits at both hospital systems, and patients with higher measure of socioeconomic disadvantage were less likely to return their kits at the safety-net hospital. These results are consistent with previously reported barriers to health and genetics care. However, other variables associated with common barriers to medical care, or personal factors associated with genetic testing motivation, were not found to be statistically significant. Patient loss to follow-up for genetic testing may be inherent to remote sample collection, beyond what is associated with known barriers to genetics care. GCs can use this information to modify how they discuss remote sample collection with their patients. Gauging patient interest about what type of sample collection may work best for them and advocating for a blood draw instead of a remotely collected sample when feasible could improve the rates of return for remote collection kits, and therefore increase the number of patients receiving genetic results that may impact care for themselves and their families

Mechanical Properties of a Complete Microtubule Revealed through Molecular Dynamics Simulation

Microtubules (MTs) are the largest type of cellular filament, essential in processes ranging from mitosis and meiosis to flagellar motility. Many of the processes depend critically on the mechanical properties of the MT, but the elastic moduli, notably the Young's modulus, are not directly revealed in experiment, which instead measures either flexural rigidity or response to radial deformation. Molecular dynamics (MD) is a method that allows the mechanical properties of single biomolecules to be investigated through computation. Typically, MD requires an atomic resolution structure of the molecule, which is unavailable for many systems, including MTs. By combining structural information from cryo-electron microscopy and electron crystallography, we have constructed an all-atom model of a complete MT and used MD to determine its mechanical properties. The simulations revealed nonlinear axial stress-strain behavior featuring a pronounced softening under extension, a possible plastic deformation transition under radial compression, and a distinct asymmetry in response to the two senses of twist. This work demonstrates the possibility of combining different levels of structural information to produce all-atom models suitable for quantitative MD simulations, which extends the range of systems amenable to the MD method and should enable exciting advances in our microscopic knowledge of biology