8 research outputs found
Structure and function of the endothelial surface layer: unraveling the nanoarchitecture of biological surfaces
Among the unsolved mysteries of modern biology is the nature of a lining of blood vessels called the 'endothelial surface layer' or ESL. In venous micro-vessels, it is half a micron in thickness. The ESL is 10 times thicker than the endothelial glycocalyx (eGC) at its base, has been presumed to be comprised mainly of water, yet is rigid enough to exclude red blood cells. How is this possible? Developments in physical chemistry suggest that the venous ESL is actually comprised of nanobubbles of CO2, generated from tissue metabolism, in a foam nucleated in the eGC. For arteries, the ESL is dominated by nanobubbles of O2 and N2 from inspired air. The bubbles of the foam are separated and stabilized by thin layers of serum electrolyte and proteins, and a palisade of charged polymer strands of the eGC. The ESL seems to be a respiratory organ contiguous with the flowing blood, an extension of, and a 'lung' in miniature. This interpretation may have far-reaching consequences for physiology
Resurrecting FUS: Adrenal Androgens as an Ultimate Cause of Hematuria, Periuria, Pollakuria, Stranguria, Urolithiasis and Obstruction in Neutered Cats
Unexpected Regeneration in Middle-Aged Mice
Complete regeneration of damaged extremities, including both the epithelium and the underlying tissues, is thought to occur mainly in embryos, fetuses, and juvenile mammals, but only very rarely in adult mammals. Surprisingly, we found that common strains of mice are able to regenerate all of the tissues necessary to completely fill experimentally punched ear holes, but only if punched at middle age. Although young postweaning mice regrew the epithelium without typical pre-scar granulation tissue, they showed only minimal regeneration of connective tissues. In contrast, mice punched at 5–11 months of age showed true amphibian-like blastema formation and regrowth of cartilage, fat, and dermis, with blood vessels, sebaceous glands, hair follicles, and, in black mice, melanocytes. These data suggest that at least partial appendage regeneration may be more common in adult mammals than previously thought and call into question the common view that regenerative ability is lost with age. The data suggest that the age at which various inbred mouse strains become capable of epimorphic regeneration may be correlated with adult body weight
X-RAY CONSTRAINTS ON THE LOCAL SUPERMASSIVE BLACK HOLE OCCUPATION FRACTION
Distinct seed formation mechanisms are imprinted upon the fraction of dwarf
galaxies currently containing a central supermassive black hole. Seeding by Pop
III remnants is expected to produce a higher occupation fraction than is
generated with direct gas collapse precursors. Chandra observations of nearby
early-type galaxies can directly detect even low-level supermassive black hole
activity, and the active fraction immediately provides a firm lower limit to
the occupation fraction. Here, we use the volume-limited AMUSE surveys of ~200
optically-selected early-type galaxies to characterize simultaneously, for the
first time, the occupation fraction and the scaling of nuclear X-ray luminosity
with stellar mass, accounting for intrinsic scatter, measurement uncertainties,
and X-ray limits. For early-type galaxies with log(M_star/M_sun)<10, we obtain
a lower limit to the occupation fraction of >20% (at 95% confidence), but full
occupation cannot be excluded. The preferred dependence of log(L_X) upon
log(M_star) has a slope of about 0.7-0.8, consistent with the "downsizing"
trend previously identified from the AMUSE dataset, and a uniform Eddington
efficiency is disfavored at ~2 sigma. We provide guidelines for the future
precision with which these parameters may be refined with larger or more
sensitive samples.Comment: Changes from v1: slightly improved galaxy distances (analysis rerun
with nearly identical results), added table with sample properties, expanded
discussion of methodology, updated references. Resubmitted to Ap