Convergence in the physical appearance of spouses

This study attempted to determine whether people who live with each other for a long period of time grow physically similar in their facial features. Photographs of couples when they were first married and 25 years later were judged for physical similarity and for the likelihood that they were married. The results showed that there is indeed an increase in apparent similarity after 25 years of cohabitation. Moreover, increase in resemblance was associated with greater reported marital happiness. Among the explanations of this phenomenon that were examined, one based on a theory of emotional efference emerged as promising. This theory proposes that emotional processes produce vascular changes that are, in part, regulated by facial musculature. The facial muscles are said to act as ligatures on veins and arteries, and they thereby are able to divert blood from, or direct blood to, the brain. An implication of the vascular theory of emotional efference is that habitual use of facial musculature may permanently affect the physical features of the face. The implication holds further that two people who live with each other for a longer period of time, by virtue of repeated empathic mimicry, would grow physically similar in their facial features. Kin resemblance, therefore, may not be simply a matter of common genes but also a matter of prolonged social contact.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45361/1/11031_2004_Article_BF00992848.pd

Dopamine Receptor Activation Increases HIV Entry into Primary Human Macrophages

Macrophages are the primary cell type infected with HIV in the central nervous system, and infection of these cells is a major component in the development of neuropathogenesis and HIV-associated neurocognitive disorders. Within the brains of drug abusers, macrophages are exposed to increased levels of dopamine, a neurotransmitter that mediates the addictive and reinforcing effects of drugs of abuse such as cocaine and methamphetamine. In this study we examined the effects of dopamine on HIV entry into primary human macrophages. Exposure to dopamine during infection increased the entry of R5 tropic HIV into macrophages, irrespective of the concentration of the viral inoculum. The entry pathway affected was CCR5 dependent, as antagonizing CCR5 with the small molecule inhibitor TAK779 completely blocked entry. The effect was dose-dependent and had a steep threshold, only occurring above 108 M dopamine. The dopamine-mediated increase in entry required dopamine receptor activation, as it was abrogated by the pan-dopamine receptor antagonist flupenthixol, and could be mediated through both subtypes of dopamine receptors. These findings indicate that the effects of dopamine on macrophages may have a significant impact on HIV pathogenesis. They also suggest that drug-induced increases in CNS dopamine may be a common mechanism by which drugs of abuse with distinct modes of action exacerbate neuroinflammation and contribute to HIV-associated neurocognitive disorders in infected drug abusers

Binding of apolipoprotein A-I model peptides to lipid bilayers : measurement of binding isotherms and peptide-lipid headgroup interactions

Amphiphatic alpha-helices are the lipid-binding motif in many apolipoproteins. Two model peptides, namely Asp-Trp-Leu-Lys-Ala-Phe-Tyr-Asp-Lys-Val-Ala-Glu-Lys-Leu-Lys-Glu-Ala-Phe (18A) and Lys-Trp-Leu-Asp-Ala-Phe-Tyr-Lys-Asp-Val-Ala-Lys-Glu-Leu-Glu-Lys-Ala- Phe (18R), have been synthesized previously to mimic the structural and functional properties of apolipoprotein A-1. Here a quantitative thermodynamic analysis of the binding process of 18A and 18R to neutral and negatively charged lipid membranes is provided. Peptide 18A has a higher lipid affinity than 18R, and both peptides bind better to mixed 1-palmitoyl-2-oleoyl-3-sn-glycero-phosphocholine-1- palmitoyl-2-oleoyl-3-sn-glycero-phosphoglycerol (POPC/POPG) bilayers than to pure POPC bilayers. At lipid-to-peptide ratios < 100, the binding of 18A and 18R to phospholipid bilayers can be described by an apparent surface partition equilibrium with binding constants in the range of 40-900 M-1. At high peptide concentrations, the membrane affinity of 18A and 18R increases dramatically. NMR studies provide evidence that peptide-peptide interactions make additional contributions to the binding energy. A cooperative binding model is developed to describe the binding process over the whole concentration range. The cooperativity parameter sigma is identical for 18A and 18R yielding a peptide-peptide interaction energy of about -2.4 kcal/mol. The free energy of membrane insertion is about -6.5 kcal/mol for 18A and -5.5 kcal/mol for 18R. The binding reaction is driven by the hydrophobic surface energy which is partially balanced by the loss in translational and rotational degrees of freedom. A molecular analysis of the free energy of binding predicts a 40-60% insertion of the peptides into the hydrophobic membrane environment. Deuterium and phosphorus solid state NMR were used to monitor the influence of 18A and 18R on the long range and short range order of the phospholipids. The spectra are characteristic of fluid-like lipid bilayers and provide no evidence for the formation of discoidal particles. However, both peptides change the conformation of the phosphocholine dipoles, moving the N+ end of the latter toward the water phase. The rotation of the -P-N+ dipoles is due to the interaction of the phospholipids with the positive charges on 18A and 18R, with 18A being more effective than 18R. For 18R the NMR data predict a pK shift and a partial charge neutralization of the carboxylate groups located at the edge of the polar/nonpolar interface