Sleep and inflammation in resilient aging.

Sleep quality is important to health, and increasingly viewed as critical in promoting successful, resilient aging. In this review, the interplay between sleep and mental and physical health is considered with a focus on the role of inflammation as a biological pathway that translates the effects of sleep on risk of depression, pain and chronic disease risk in aging. Given that sleep regulates inflammatory biologic mechanisms with effects on mental and physical health outcomes, the potential of interventions that target sleep to reduce inflammation and promote health in aging is also discussed

The Optical Velocity of the Antlia Dwarf Galaxy

We present the results of a VLT observing program carried out in service mode using FORS1 on ANTU in Long Slit mode to determine the optical velocities of nearby low surface brightness galaxies. Outlying Local Group galaxies are of paramount importance in placing constraints the dynamics and thus on both the age and the total mass of the Local Group. Optical velocities are also necessary to determine if the observations of HI gas in and around these systems are the result of gas associated with these galaxies or a chance superposition with high velocity HI clouds or the Magellanic Stream. The data were of sufficient signal-to-noise to obtain a reliable result in one of the galaxies we observed - Antlia - for which we have found an optical helio-centric radial velocity of 351 $\pm$ 15 km/s.Comment: 11 pages, 4 figures, 5 tables MNRAS, in pres

Mindfulness meditation and improvement in depressive symptoms among Spanish- and English speaking adults: A randomized, controlled, comparative efficacy trial.

ObjectiveLatino immigrants experience acculturative stress and increased depression risk. Mindfulness meditation improves depressive symptoms, yet the vast majority of research has focused on English speaking populations.MethodsIn this randomized clinical trial with 2 parallel treatment groups, adults with moderate levels of perceived stress (n = 76) were recruited from the Los Angeles community from October 2015 to March 2016, stratified into Spanish- (n = 36) and English speaking (n = 40) language groups, and randomized for 6 weeks of treatment with standardized mindful awareness practices (MAPs) or health education (HE). Main outcome measure was depressive symptoms, measured by the Beck Depression Inventory.ResultsUsing an intent-to-treat analysis, the primary outcome, depressive symptoms as indexed by the Beck Depression Inventory, showed greater improvement in MAPs vs. HE, with a between-group post-intervention mean difference of -2.2 (95% CI -4.4 - -0.07) and effect size of 0.28; similar effect sizes were found in the the Spanish- (0.29) and English speaking (0.30) groups. MAPs showed significant improvement relative to HE on secondary outcome of mindfulness with between group difference of 10.7 (95% CI4.5-16.9), but not perceived stress.ConclusionThe comparable efficacy of Spanish and English formats of mindfulness meditation in improving depressive symptoms suggests that this community based intervention may mitigate depression risk in Latino adults who are experiencing social adversity.Trial registrationClinicalTrials.gov NCT03545074

Galactic Halo substructure in the Sloan Digital Sky Survey: the ancient tidal stream from the Sagittarius dwarf galaxy

Two studies have recently reported the discovery of pronounced Halo substructure in the Sloan Digital Sky Survey (SDSS) commissioning data. Here we show that this Halo substructure is almost in its entirety due to the expected tidal stream torn off the Sagittarius dwarf galaxy during the course of its many close encounters with the Milky Way. This interpretation makes strong predictions on the kinematics and distances of these stream stars. Comparison of the structure in old horizontal branch stars, detected by the SDSS team, with the carbon star structure discovered in our own survey, indicates that this halo stream is of comparable age to the Milky Way. It would appear that the Milky Way and the Sagittarius dwarf galaxy have been a strongly interacting system for most of their existence. Once complete, the SDSS will provide a unique dataset with which to constrain the dynamical evolution of the Sagittarius dwarf galaxy, it will also strongly constrain the mass distribution of the outer Milky Way.Comment: 7 pages, 3 figures (1 color figure chunky due to PS compression), minor revisions,accepted by ApJ

MOLECULAR ARCHITECTURE OF ROD PHOTORECEPTOR PHOSPHODIESTERASE IN ITS NONACTIVATED AND G-PROTEIN ACTIVATED STATES

The photoreceptor phosphodiesterase (PDE6) plays an important role in the G-protein coupled visual signaling pathway which uses cGMP as a second messenger to convert light stimuli into electrical signals. PDE6 is a tetrameric peripheral membrane protein consisting of two catalytic subunits and two inhibitory subunits and is localized to the outer segment membranes of rod and cone photoreceptors. Mutations in this enzyme are one cause of retinitis pigmentosa and other retinal degenerative diseases resulting in blindness or visual dysfunction that lack adequate therapeutic intervention due to inadequate knowledge of PDE6 structure and regulation PDE6 is tightly regulated in the nonactivated state, as well as during activation and deactivation of the visual signaling pathway. In the nonactivated state, the rod PDE6 catalytic dimer (consisting of the Pα and Pβ catalytic subunits) is inhibited by a pair of identical inhibitory subunits (Pγ) to form the PDE6 holoenzyme (Pαβγγ). Activation of PDE6 results from displacement of the Pγ subunit by the light-activated G protein alpha-subunit (Gtα). Deactivation of PDE6 is the result of the GTPase activity of Gtα which is aided by a GTPase accelerating complex consisting of the Regulator of G Protein Signaling 9 (RGS9-1), the obligate dimer to RGS9-1, Gβ5L, and the RGS9-1 anchoring protein (R9AP). Together this inactivation complex allows PDE6 to return to the nonactivated conformation. The hypotheses of my research are: (1) silica particles encased by large unilamellar phospholipid vesicles will mimic the photoreceptor membrane and provide a surface suitable for enhancing the interactions of PDE6 and Gtα as well as the proteins involved in the deactivation complex; (2) one Gtα molecule binds to each PDE6 catalytic domain and induces a large conformational change in the inhibitory Pγ subunit; (3) interaction of RGS9-1 with Gtα will induce changes in the interaction surface between activated Gtα and PDE6, allowing Pγ to resume the conformation which inhibits PDE6 activity. The first aim of my research is to establish a methodology to study PDE6 and its associated complexes in a system that mimics the rod outer segment. In order to achieve this, a protocol for encasing silica particles in large unilamellar phospholipid vesicles (called “lipobeads”) was developed. This methodology not only allowed for an increase in the extent of Gtα activation when compared to PDE6 in solution, but also allowed for study of membrane-attached PDE6 and Gtα at concentrations that more closely mimic those observed in the rod outer segment. The second aim of my research is to characterize the structure of membrane-attached PDE6 in its nonactivated state and in the fully activated state upon binding of Gtα. This was achieved using chemical crosslinking and mass spectrometry in conjunction with a computational modeling program called the Integrative Modelling Platform. In the nonactivated state, it was observed the Pγ has significant interaction with the regulatory GAFa domain as well as the catalytic domain of Pαβ while displaying a less well defined structure in the central cationic region of Pγ. Upon activation, two Gtα are bound to specific docking sites on PDE6 resulting in the displacement of Pγ from both catalytic domains as well as a predicted shift of Pγ away from GAFa. The third aim of my research is to understand the sequential activation mechanism of PDE6 by Gtα. Chemical crosslinking and mass spectrometry was again used in order to characterize the structures of PDE6 with a sub-stoichiometric amount of Gtα as well as a slight stoichiometric excess of Gtα (0.4:1 and 3:1 Gtα:PDE6, respectively). In the case of the stoichiometric excess, a high molecular weight cross-linked band on SDS-PAGE indicative of two Gtα bound to PDE6 was structurally analyzed; the sub-stoichiometric condition resulted in a single Gtα bound species which was also analyzed. Comparisons were also made between the inactive (Gtα-GDP) and activated (Gtα*-GDP-AlF4-) states. This work showed that when two activated Gtα* molecules were bound to PDE6 both Gtα subunits were associated with the catalytic domains of PDE6. When Gtα was present at sub-stoichiometric levels relative to PDE6, a single docking site was identified in proximity to the GAFb domains of PDE6. The inactive state of Gtα (Gtα-GDP) also was capable of binding PDE6 but bound only to the GAFb domains. Measurements of PDE catalytic activity established two Gtα-GDP-AlF4- molecules were able to produce significant activation of PDE6, whereas the sub-stoichiometric condition (0.4 Gtα per PDE6) did not produce activity above basal levels. These results indicate that the binding of a single Gtα is not sufficient to stimulate activity of PDE6. The final aim of my research is to establish a methodology for the study of the deactivation complex of PDE6. To achieve this aim, lipobeads were used in order to anchor the integral membrane protein R9AP to produce “proteolipobeads”. This membrane-embedded R9AP preparation was then able to bind the RGS9-1/Gβ5L without affecting the ability of PDE6 and Gtα to also bind to the proteolipobeads. Chemical crosslinking and mass spectrometry analysis confirmed that all of the proteins were present on the membrane and in close enough proximity to allow future analysis of the PDE6 inactivation complex

MOLECULAR ARCHITECTURE OF ROD PHOTORECEPTOR PHOSPHODIESTERASE IN ITS NONACTIVATED AND G-PROTEIN ACTIVATED STATES

The photoreceptor phosphodiesterase (PDE6) plays an important role in the G-protein coupled visual signaling pathway which uses cGMP as a second messenger to convert light stimuli into electrical signals. PDE6 is a tetrameric peripheral membrane protein consisting of two catalytic subunits and two inhibitory subunits and is localized to the outer segment membranes of rod and cone photoreceptors. Mutations in this enzyme are one cause of retinitis pigmentosa and other retinal degenerative diseases resulting in blindness or visual dysfunction that lack adequate therapeutic intervention due to inadequate knowledge of PDE6 structure and regulation PDE6 is tightly regulated in the nonactivated state, as well as during activation and deactivation of the visual signaling pathway. In the nonactivated state, the rod PDE6 catalytic dimer (consisting of the Pα and Pβ catalytic subunits) is inhibited by a pair of identical inhibitory subunits (Pγ) to form the PDE6 holoenzyme (Pαβγγ). Activation of PDE6 results from displacement of the Pγ subunit by the light-activated G protein alpha-subunit (Gtα). Deactivation of PDE6 is the result of the GTPase activity of Gtα which is aided by a GTPase accelerating complex consisting of the Regulator of G Protein Signaling 9 (RGS9-1), the obligate dimer to RGS9-1, Gβ5L, and the RGS9-1 anchoring protein (R9AP). Together this inactivation complex allows PDE6 to return to the nonactivated conformation. The hypotheses of my research are: (1) silica particles encased by large unilamellar phospholipid vesicles will mimic the photoreceptor membrane and provide a surface suitable for enhancing the interactions of PDE6 and Gtα as well as the proteins involved in the deactivation complex; (2) one Gtα molecule binds to each PDE6 catalytic domain and induces a large conformational change in the inhibitory Pγ subunit; (3) interaction of RGS9-1 with Gtα will induce changes in the interaction surface between activated Gtα and PDE6, allowing Pγ to resume the conformation which inhibits PDE6 activity. The first aim of my research is to establish a methodology to study PDE6 and its associated complexes in a system that mimics the rod outer segment. In order to achieve this, a protocol for encasing silica particles in large unilamellar phospholipid vesicles (called “lipobeads”) was developed. This methodology not only allowed for an increase in the extent of Gtα activation when compared to PDE6 in solution, but also allowed for study of membrane-attached PDE6 and Gtα at concentrations that more closely mimic those observed in the rod outer segment. The second aim of my research is to characterize the structure of membrane-attached PDE6 in its nonactivated state and in the fully activated state upon binding of Gtα. This was achieved using chemical crosslinking and mass spectrometry in conjunction with a computational modeling program called the Integrative Modelling Platform. In the nonactivated state, it was observed the Pγ has significant interaction with the regulatory GAFa domain as well as the catalytic domain of Pαβ while displaying a less well defined structure in the central cationic region of Pγ. Upon activation, two Gtα are bound to specific docking sites on PDE6 resulting in the displacement of Pγ from both catalytic domains as well as a predicted shift of Pγ away from GAFa. The third aim of my research is to understand the sequential activation mechanism of PDE6 by Gtα. Chemical crosslinking and mass spectrometry was again used in order to characterize the structures of PDE6 with a sub-stoichiometric amount of Gtα as well as a slight stoichiometric excess of Gtα (0.4:1 and 3:1 Gtα:PDE6, respectively). In the case of the stoichiometric excess, a high molecular weight cross-linked band on SDS-PAGE indicative of two Gtα bound to PDE6 was structurally analyzed; the sub-stoichiometric condition resulted in a single Gtα bound species which was also analyzed. Comparisons were also made between the inactive (Gtα-GDP) and activated (Gtα*-GDP-AlF4-) states. This work showed that when two activated Gtα* molecules were bound to PDE6 both Gtα subunits were associated with the catalytic domains of PDE6. When Gtα was present at sub-stoichiometric levels relative to PDE6, a single docking site was identified in proximity to the GAFb domains of PDE6. The inactive state of Gtα (Gtα-GDP) also was capable of binding PDE6 but bound only to the GAFb domains. Measurements of PDE catalytic activity established two Gtα-GDP-AlF4- molecules were able to produce significant activation of PDE6, whereas the sub-stoichiometric condition (0.4 Gtα per PDE6) did not produce activity above basal levels. These results indicate that the binding of a single Gtα is not sufficient to stimulate activity of PDE6. The final aim of my research is to establish a methodology for the study of the deactivation complex of PDE6. To achieve this aim, lipobeads were used in order to anchor the integral membrane protein R9AP to produce “proteolipobeads”. This membrane-embedded R9AP preparation was then able to bind the RGS9-1/Gβ5L without affecting the ability of PDE6 and Gtα to also bind to the proteolipobeads. Chemical crosslinking and mass spectrometry analysis confirmed that all of the proteins were present on the membrane and in close enough proximity to allow future analysis of the PDE6 inactivation complex