Selective proteolysis of ovine lutropin or its beta subunit by endoproteinase Arg-C. Properties of the Arg beta 43 cleaved hormone

Ovine lutropin (oLH) and its beta subunit (oLH beta) were nicked by short-term incubations with endoproteinase Arg-C. Isolated oLH beta was rapidly nicked and converted from an Mr 18,000 band on sodium dodecyl sulfate-polyacrylamide gels to an Mr 13,000 band. Partial nicking of only the beta subunit in intact oLH was also observed as indicated by the appearance of small amounts of the Mr 13,000 band detected in Arg-C-treated oLH samples. The alpha subunit was protected by association with the beta subunit, but free alpha subunit was rapidly degraded. Sequence analysis of nicked oLH beta indicated that one of the peptide bonds on either side of Arg43 was cleaved by the protease, with a slight preference for the amino side of this residue. Nicked oLH beta was reassociated with oLH alpha, and the resulting dimer was separated from unrecombined subunits. The biologic activity of nicked oLH beta + oLH alpha in an LH radioligand assay was only 2% that of intact oLH.     

Human Brain Microvascular Endothelial Cells Derived from the BC1 iPS Cell Line Exhibit a Blood-Brain Barrier Phenotype

The endothelial cells that form capillaries in the brain are highly specialized, with tight junctions that minimize paracellular transport and an array of broad-spectrum efflux pumps that make drug delivery to the brain extremely challenging. One of the major limitations in blood-brain barrier research and the development of drugs to treat central nervous system diseases is the lack of appropriate cell lines. Recent reports indicate that the derivation of human brain microvascular endothelial cells (hBMECs) from human induced pluripotent stem cells (iPSCs) may provide a solution to this problem. Here we demonstrate the derivation of hBMECs extended to two new human iPSC lines: BC1 and GFP-labeled BC1. These hBMECs highly express adherens and tight junction proteins VE-cadherin, ZO-1, occludin, and claudin-5. The addition of retinoic acid upregulates VE-cadherin expression, and results in a significant increase in transendothelial electrical resistance to physiological values. The permeabilities of tacrine, rhodamine 123, and Lucifer yellow are similar to values obtained for MDCK cells. The efflux ratio for rhodamine 123 across hBMECs is in the range 2–4 indicating polarization of efflux transporters. Using the rod assay to assess cell organization in small vessels and capillaries, we show that hBMECs resist elongation with decreasing diameter but show progressive axial alignment. The derivation of hBMECs with a blood-brain barrier phenotype from the BC1 cell line highlights that the protocol is robust. The expression of GFP in hBMECs derived from the BC1-GFP cell line provides an important new resource for BBB research.     

Synthesis of ABO histo-blood group type I and II antigens

The ABO histo-blood group system is one of the most clinically important antigen families. As part of our overall goal to prepare the entire set of the A, B and H type I-VI antigens for a range of biochemical investigations, we report herein the synthesis of the type I and II antigens with a 7-octen-1-yl aglycone. This linker was chosen to facilitate not only the future conjugation of the antigens to a protein or solid support but also the synthesis of the H type I and II octyl glycosides for enzyme kinetic studies.     

Radiation injury in rat lung. I. Prostacyclin (PGI2) production, arterial perfusion, and ultrastructure

Pulmonary prostacyclin (PGI2) production, arterial perfusion, and ultrastructure were correlated in rats sacrificed from 1 day to 6 months after a single exposure of 25 Gy of gamma rays to the right hemithorax. PGI2 production by the irradiated lung decreased to approximately half the normal value 1 day after irradiation (P less than 0.05), then increased steadily throughout the study. By 6 months postirradiation, the right lung produced two to three times as much PGI2 as did either shielded left lung or sham-irradiated lungs (P less than 0.05). Perfusion scans revealed hyperemia of the right lung from 1 to 14 days after irradiation. From its peak at 14 days postirradiation, however, perfusion of the irradiated lung decreased steadily, then reached a plateau from 3 to 6 months at less than half that in the shielded left lung. Electron micrographs of the right lung revealed perivascular edema from 1 to 30 days after irradiation. The right lung then exhibited changes typical of radiation pneumonitis followed by progressive interstitial fibrosis. Platelet aggregates were not observed at any time. Thus, decreased PGI2 production is an immediate but transient response of the lung to radiation injury. Then from 2 to 6 months after irradiation, the fibrotic, hypoperfused lung produces increasing amounts of the potent vasodilator and antithrombotic agent, PGI2. Pulmonary PGI2 production and arterial perfusion are inversely correlated for at least 6 months after hemithoracic irradiation.     

Voting with your feet: Payoff biased migration and the evolution of group beneficial behavior

Human migration is nonrandom. In small scale societies of the past, and in the modern world, people tend to move to wealthier, safer, and more just societies from poorer, more violent, less just societies. If immigrants are assimilated, such nonrandom migration can increase the occurrence of culturally transmitted beliefs, values, and institutions that cause societies to be attractive to immigrants. Here we describe and analyze a simple model of this process. This model suggests that long run outcomes depend on the relative strength of migration and local adaptation. When local adaption is strong enough to preserve cultural variation among groups, cultural variants that make societies attractive always predominate, but never drive alternative variants to extinction. When migration predominates, outcomes depend both on the relative attractiveness of alternative variants and on the initial sizes of societies that provide and receive immigrants.