Surface Properties Of The Arterial Wall And Their Relevance To Atherosclerosis

Adhesion of platelets to the arterial subendothelium exposed by injury to the endothelium, is thought to initiate atherosclerosis. Thermodynamically, adhesion will occur if it decreases the free energy of the system. Here, I have developed a contact angle technique to measure relative changes in the interfacial free energy of the arterial wall, before and after removal of the endothelium. Sections of aorta were tested with an equilibrium two phase system of 4% poly (ethylene glycol) (PEG)/4% dextran, in buffered physiological saline. The tissue was immersed in the PEG phase and droplets of the denser dextran phase were placed on its lumenal surface. After testing, the endothelium was removed with a saline jet, and the tissue was retested. Contact angles of 86.0 (+OR-) 1.1(DEGREES) (SEM), n = 64 for the intact endothelium, and 20.0 (+OR-) 0.08 (SEM), n = 61 on the subendothelium, were measured from photomicrographs. Since the physical behavior of blood is similar to the PEG phase, the subendothelium probably represents a high energy surface in vivo, thus promoting platelet adhesion.;Factors which cause endothelial injury may act chronically at the cell surface to cause desquamation. To test this hypothesis, rabbits fed a 2% cholesterol diet to induce atherosclerosis were divided into 3 experimental groups: continuous feeding, interrupted feeding, and controls. Areas proximal and distal to intercostal orifices, where no plaque had yet developed, were tested with the PEG/dextran system. Proximal areas on the diseased arteries, and both the proximal and distal locations in controls gave contact angles of approximately 90(DEGREES); however those areas distal to orifices, where lesions eventually occur, yielded significantly different angles, 78(DEGREES). This difference indicates a change in the glycocalyx, which could weaken the cell resistance to injury, leading to desquamation, platelet adhesion and plaque formation

CAG expansion affects the expression of mutant huntingtin in the Huntington's disease brain

AbstractA trinucleotide repeat (CAG) expansion in the huntingtin gene causes Huntington's disease (HD). In brain tissue from HD heterozygotes with adult onset and more clinically severe juvenile onset, where the largest expansions occur, a mutant protein of equivalent intensity to wild-type huntingtin was detected in cortical synaptosomes, indicating that a mutant species is synthesized and transported with the normal protein to nerve endings. The increased size of mutant huntingtin relative to the wild type was highly correlated with CAG repeat expansion, thereby linking an altered electrophoretic mobility of the mutant protein to its abnormal function. Mutant huntingtin appeared in gray and white matter with no difference in expression in affected regions. The mutant protein was broader than the wild type and in 6 of 11 juvenile cases resolved as a complex of bands, consistent with evidence at the DNA level for somatic mosaicism. Thus, HD pathogenesis results from a gain of function by an aberrant protein that is widely expressed in brain and is harmful only to some neurons

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Hitomi (ASTRO-H) X-ray Astronomy Satellite

The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E  >  2  keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month