Pilot Study Evaluating Critical Time Intervention for Individuals With Hoarding Disorder at Risk for Eviction.

Hoarding disorder has significant health consequences, including the devastating threat of eviction. In this pilot study, critical time intervention (CTI), an evidence-based model of case management shown to be effective for vulnerable populations, was adapted for individuals with severe symptoms of hoarding disorder at risk for eviction (CTI-HD). Of the 14 adults who enrolled, 11 participants completed the 9-month intervention. Completers reported a modest decrease in hoarding severity, suggesting that, while helpful, CTI-HD alone is unlikely to eliminate the risk of eviction for individuals with severe symptoms of hoarding disorder.

Search for extraterrestrial life using chiral molecules: mandelate racemase as a test case.

We have investigated an enzymatic racemization reaction as a marker for extraterrestrial life, which resulted in a change in optical rotation of a mandelic acid over time, as measured by polarimetry. Mandelate racemase was active in aqueous buffer in a temperature range between 0 degrees C and 70 degrees C and also in concentrated ammonium salt solutions and water-in-oil microemulsions in a temperature range between -30 degrees C and 60-70 degrees C; however, the enzyme was not active in several organic cryosolvents. Thus, we have demonstrated that concentrated ammonium salt solutions and water-in-oil microemulsions, both of which are able to form on extraterrestrial planets and moons in the presence of liquid water, are suitable media for enzyme reactions at subzero temperatures. Kinetic data for the mandelate racemase reaction obtained by polarimetry, while reproducible and internally consistent, differed significantly from several sets of data obtained previously by other methods such as chromatography and hydrogen-deuterium exchange. However, we conclude that reactions yielding a polarimetric signal, such as the racemizations employed in this work, are suitable mechanisms by which to utilize a change in chirality over time as a tool to detect signs of life.

Astrobiological polarimeter.

Chirality is an excellent indicator of life, but naturally occurring astrobiological (as well as terrestrial) samples nearly always exhibit massive depolarizing light scattering, which renders conventional polarimeters useless. For astrobiological applications, we instead consider a novel polarimeter originally developed for non-invasive human-glucose measurement. It involves deliberately rotating in time the plane of polarization of a linearly polarized beam and detecting the shift in the plane of the rotating linearly polarized component of the transmitted light from a chiral sample relative to the input polarization plane. We find that this polarimeter can operate in 3 orders of magnitude more depolarizing scattering than conventional polarimeters. Furthermore, it can also be designed to be lightweight, compact, and energy efficient.

The crystal structure of NAD(P)H oxidase from Lactobacillus sanfranciscensis: insights into the conversion of O2 into two water molecules by the flavoenzyme.

The FAD-dependent NAD(P)H oxidase from Lactobacillus sanfrancisensis (L.san-Nox2) catalyzes the oxidation of 2 equivalents of either NADH or NADPH and reduces 1 equivalent of O(2) to yield 2 equivalents of water. During steady-state turnover only 0.5% of the reducing equivalents are detected in solution as hydrogen peroxide, suggesting that it is not released from the enzyme after the oxidation of the first equivalent of NAD(P)H and reaction with O(2). Here we report the crystal structure of L.san-Nox2 to 1.8 A resolution. The enzyme crystallizes as a dimer with each monomer consisting of a FAD binding domain (residues 1-120), a NAD(P)H binding domain (residues 150-250), and a dimerization domain (residues 325-451). The electron density for the redox-active Cys42 residue located adjacent to the si-face FAD is consistent with oxidation to the sulfenic acid (Cys-SOH) state. The side chain of Cys42 is also observed in two conformations; in one the sulfenic acid is hydrogen bonded to His10 and in the other it hydrogen bonds with the FAD O2' atom. Surprisingly, the NAD(P)H binding domains each contain an ADP ligand as established by electron density maps and MALDI-TOF analysis of the ligands released from heat-denatured enzyme. The ADP ligand copurifies with the enzyme, and its presence does not inhibit enzyme activity. Consequently, we hypothesize that either NADPH or NADH substrates bind via a long channel that extends from the enzyme exterior and terminates at the FAD re-face. A homology model of the NADH oxidase from Lactococcus lactis (L.lac-Nox2) was also generated using the crystal structure of L.san-Nox2, which reveals several important similarities and differences between the two enzymes. HPLC analysis of ligands released from denatured L.lac-Nox2 indicates that it does not bind ADP, which correlates with the specificity of the enzyme for oxidation of NADH.