Theoretical study on electronic spectra and interaction in [Au3]-L-[Au3] (L = C6F6,Ag+) complexes

The electronic structure and spectroscopic properties of [Au₃(μ-C(OEt) = NC₆H₄CH₃)₃]_n-(C₆F₆)_m and [Au₃(μ-C²,N³-bzim)₃]_n-(Ag⁺)_m were studied at the B3LYP, PBE and TPSS levels. The interaction between the [Au₃] cluster and L (C₆F₆, Ag⁺) was analyzed. Grimme’s dispersion correction is used for those functionals. Weak π-interactions (Au-C₆F₆) were found to be the main contribution short-range stability in the models; while in the models with Ag⁺, an ionic interaction is obtained. The absorption spectra of these models at the PBE level agree with the experimental spectra.     

Effect of a chronic infusion of atrial natriuretic peptide on vascular reactivity in normotensive and renal hypertensive rats

In a previous study, we found that a long-term infusion of atrial natriuretic peptide (ANP) produced a sustained reduction of mean arterial pressure and peripheral vascular resistance in two-kidney, one-clip (2K-1C) hypertensive rats, whereas in control rats it had only a transient effect on cardiac output. However, plasma levels of ANP were actually 3-fold higher in normotensive than in hypertensive rats. Previous studies suggested that plasma ANP levels might modulate the vascular reactivity to the peptide. The present study examined whether the lack of chronic hemodynamic effects of ANP in control rats was due to changes in vascular reactivity to the peptide. In control rats, vascular reactivity to ANP was reduced 50% by a chronic infusion of ANP. However, in 2K-1C hypertensive rats, a long-term infusion of ANP had no effect on the vascular reactivity to ANP. The results of the present study indicate that the lack of persistent hemodynamic effects of a chronic infusion of ANP in control rats may be due to a decrease in the vascular reactivity to the peptide. The sustained hypotensive and vasodilatory effects of a long-term infusion of ANP in 2K-1C hypertensive rats are associated with no changes in the vascular reactivity to ANP.     

Cardiac GPCRs: GPCR signaling in healthy and failing hearts

G protein-coupled receptors (GPCRs) are widely implicated in human heart disease, making them an important target for cardiac drug therapy. The most commonly studied and clinically targeted cardiac GPCRs include the adrenergic, angiotensin, endothelin, and adenosine receptors. Treatment options focusing on the complex and integrated signaling pathways of these GPCRs are critical for the understanding and amelioration of heart disease. The focus of this review is to highlight the most commonly studied and clinically targeted cardiac GPCRs, placing emphasis on their common signaling components implicated in cardiac disease.     

Characterization of the two rRNA gene operons present in Thiobacillus ferrooxidans

The organization of rRNA genes from the autotrophic, acidophilic bacterium Thiobacillus ferrooxidans has been examined. Two rRNA operons were found in this microorganism by means of genomic hybridization studies. Recombinant plasmids, pTR-3 and pTR-1 that carry a portion of 16/23 S rDNA from one operon and the 5'-flanking region of the second operon, respectively, were identified and characterized.     

Sluggish Movement and Repugnant Odor Are Positively Interacting Insect Defensive Traits in Encounters with Frogs

Sluggish movement is common in chemically defended insects. We have recently shown that sluggish movement can be beneficial to prey when it fails to release the attack response of an ambush (=motion-oriented) predator. Here, we test the hypothesis that sluggish movement and chemical defense (i.e., repugnant odor) together are more defensive than either alone. We manipulated the movement and odor of lubber grasshoppers to produce four prey types: (1) sluggish-moving and high odor, (2) sluggish-moving and low odor, (3) fast-moving and high odor, and (4) fast-moving and low odor. We then offered these prey to frogs. In two independent experiments, frogs attacked prey type 1 (i.e., sluggish-moving and high-odor prey) significantly later than they attacked the other prey types. Hence, the defenses of sluggish movement and repugnant odor can act together to produce a prey that is better defended than prey with either defense alone. This may help explain why these two traits commonly cooccur in insects.