Rotation function studies of human C-reactive protein

Rotation function studies of two tetragonal crystal forms of human C-reactive protein have confirmed the pentameric structure of the molecule. The two crystal forms have space groups P4122 (I) and P4222 (II) with closely similar unit cells and are often twinned together. Investigation of the crystallization conditions indicates that dissociation heterogeneity has been a major limiting factor in the reproducible growth of good single crystals. The orientation of the pentameric molecule is shown to be almost identical in both forms, about the axial direction omega = 57 degrees, phi = 45 degrees, i.e. 57 degrees away from c in the (110) plane.     

In silico study of bone tissue regeneration in an idealised porous hydrogel scaffold using a mechano-regulation algorithm

Mechanical stimulation, in the form of fluid perfusion or mechanical strain, enhances osteogenic differentiation and overall bone tissue formation by mesenchymal stems cells cultured in biomaterial scaffolds for tissue engineering applications. In silico techniques can be used to predict the mechanical environment within biomaterial scaffolds, and also the relationship between bone tissue regeneration and mechanical stimulation, and thereby inform conditions for bone tissue engineering experiments. In this study, we investigated bone tissue regeneration in an idealised hydrogel scaffold using a mechano-regulation model capable of predicting tissue differentiation, and specifically compared five loading cases, based on known experimental bioreactor regimes. These models predicted that low levels of mechanical loading, i.e. compression (0.5% strain), pore pressure of 10 kPa and a combination of compression (0.5%) and pore pressure (10 kPa), could induce more osteogenic differentiation and lead to the formation of a higher bone tissue fraction. In contrast greater volumes of cartilage and fibrous tissue fractions were predicted under higher levels of mechanical loading (i.e. compression strain of 5.0% and pore pressure of 100 kPa). The findings in this study may provide important information regarding the appropriate mechanical stimulation for in vitro bone tissue engineering experiments.     

Why Did U.S. Healthcare Professionals Become Involved in Torture During the War on Terror?

This article examines why U.S. healthcare professionals became involved in “enhanced interrogation,” or torture, during the War on Terror. A number of factors are identified including a desire on the part of these professionals to defend their country and fellow citizens from future attack; having their activities approved and authorized by legitimate command structures; financial incentives; and wanting to prevent serious harm from occurring to prisoners/detainees. The factors outlined here suggest that psychosocial factors can influence health professionals’ ethical decision-making.     

Contraction of bovine coronary vascular smooth muscle induced by cocaine is not mediated by norepinephrine

This study was designed to assess the effects of cocaine on coronary arterial smooth muscle and to determine whether previously reported cocaine-induced coronary vasospasm is mediated by substances released from the endothelium or by increased adrenergic receptor stimulation. Concentration-response relationships for cocaine (0.1-300 microM) and norepinephrine (0.1-300 microM) were studied in vitro using 2 mm segments of bovine proximal left anterior descending coronary artery. Each segmental ring was mounted in a 70 ml tissue bath for the measurement of isometric tension. Cocaine (3-300 microM) caused significant, concentration-dependent, increases in developed tension (p less than 0.05). Removal of the endothelium or pretreatment with prazosin (0.1 microM) or propranolol (1 microM) did not significantly alter this action of cocaine. In contrast to cocaine, norepinephrine (10-300 microM) caused significant decreases in developed tension (p less than 0.01). These findings suggest that cocaine-induced contraction of bovine coronary vascular smooth muscle is not mediated by endothelium derived contracting substances or norepinephrine.     

Preliminary X-ray study of crystals of human C-reactive protein

Two different crystal forms of human C-reactive protein have been grown from solutions of 2-methyl-2,4-pentanediol. Both crystal forms are tetragonal, the space group for form I is P4(1)22 (or P4(3)22), and that for form II is P4(2)22. The unit cell parameters for form I are a = b = 103.0(5) A, c = 308.5(7) A and for form II are a = b = 103.1(2) A, c = 312.7(6) A. The crystals of form II diffract to at least 3.0 A resolution, and are suitable for detailed structural studies.