Effect of vitamin D on depression: an experimental study

Background: There is a scarcity of studies regarding antidepressant activity of vitamin D in animals while there are some contradictory reports regarding the same in humans. Therefore the present study was planned to investigate the antidepressant effect of vitamin D and its interaction with standard antidepressant drugs in animals.Methods: Forced swim test (FST) in adult male Wistar rats and tail suspension test (TST) in adult male Swiss albino mice were used to investigate antidepressant activity of vitamin D administered in single dose and multiple doses. Imipramine, a tri-cyclic antidepressant and fluoxetine, a selective serotonin reuptake inhibitor were used as standard antidepressant drugs. For interaction studies, half the therapeutic equivalent dose of vitamin D was combined with sub-effective dose (SED) of imipramine or fluoxetine. Data was expressed as Mean±SD and analyzed by standard statistical tests. P<0.05= significant. Present study was ethically approved.Results: Single dose administration of vitamin D did not show significant antidepressant effect either in FST or TST. Multiple dose administration of vitamin D showed significant antidepressant activity in TST but not in FST. Combination of vitamin D (half dose) with SED of either standard antidepressant drugs did not show any significant antidepressant activity. None of the treatment groups showed any significant difference on locomotor activity.Conclusions: In the present study, multiple dose administration of vitamin D showed some antidepressant activity. Further studies are needed to confirm and elaborate the role of vitamin D in behavioral disorders like depression

A missense variant (P10L) of the melanopsin (OPN4) gene in seasonal affective disorder

Background: Melanopsin, a non-visual photopigment, may play a role in aberrant responses to low winter light levels in Seasonal Affective Disorder (SAD). We hypothesize that functional sequence variation in the melanopsin gene could contribute to increasing the light needed for normal functioning during winter in SAD. Methods: Associations between alleles, genotypes, and haplotypes of melanopsin in SAD participants (n = 130) were performed relative to controls with no history of psychopathology (n = 90). Results: SAD participants had a higher frequency of the homozygous minor genotype (T/T) for the missense variant rs2675703 (P10L) than controls, compared to the combined frequencies of C/C and C/T. Individuals with the T/T genotype were 5.6 times more likely to be in the SAD group than the control group, and all 7 (5%) of individuals with the T/T genotype at P10L were in the SAD group. Limitations: The study examined only one molecular component of the non-visual light input pathway, and recruitment methods for the comparison groups differed. Conclusion: These findings support the hypothesis that melanopsin variants may predispose some individuals to SAD. Characterizing the genetic basis for deficits in the non-visual light input pathway has the potential to define mechanisms underlying the pathological response to light in SAD, which may improve treatment. © 2008 Elsevier B.V

Enabling Sharing in Auctions for Short-Term Spectrum Licenses

Wireless spectrum is a valuable and scarce resource that currently suffers from under-use because of the dominant paradigm of exclusive-use licensing. We propose the SATYA auction (Sanskrit for truth), which allows short-term leases to be auctioned and supports diverse bidder types, including those willing to share access and those who require exclusive-use access. Thus, unlike unlicensed spectrum such as Wi-Fi, which can be shared by any device, and exclusive-use licensed spectrum, where sharing is precluded, SATYA improves efficiency through supporting sharing alongside quality-of-service protections. The auction is designed to be scalable, and also strategy proof, so that simple bidding protocols are optimal. The primary challenge is to handle the externalities created by allocating shared-use alongside exclusive-use bidders. Using realistic Longley-Rice based propagation modeling and data from the FCC’s CDBS database, we conduct extensive simulations that demonstrate SATYA’s ability to handle heterogeneous bidders involving different transmit powers and spectrum needs.Engineering and Applied Science

Microbially induced sedimentary structures in the Paleoproterozoic, upper Huronian Supergroup, Canada

The Paleoproterozoic Gordon Lake and Bar River formations, Huronian Supergroup, contain a variety of sedimentary structures in the Flack Lake area of Ontario, Canada, that have been considered of debatable origin. We identify these structures as microbially induced sedimentary structures (MISS). The preserved MISS are related to microbial mat destruction and decay, and include sand cracks, mat chips, remnant gas domes, pyrite patches, and iron laminae. A biological origin for the fossil structures is supported by their similarities to modern and ancient documented examples of MISS, the sand-dominated nature of the substrate in which they are preserved, and key microtextures identified in thin section. Microtextures include curled, frayed and layered mat chips, carbonaceous laminae, oriented grains, and concentrated heavy minerals. On outcrop scale, the presence of desiccation cracks, flaser and lenticular bedding, and ripples in association with the types of MISS identified in the Gordon Lake Formation support the interpretation of a tidal flat depositional environment. The Gordon Lake Formation contains a greater number and diversity of MISS than the overlying Bar River Formation, as a result of lower energy deposition in the former. The quartz arenite of the Bar River Formation contains fine-grained to pebbly granulestone characterized mainly by tangential and planar cross beds, which is consistent with a tidal channel or sand shoal setting. Although fossil evidence of life is rare in the rocks of the Huronian Supergroup, identification of MISS in the Flack Lake area provides a significant and convincing indication of microbial colonization at the time of deposition

Are Particles in Advection-Dominated Accretion Flows Thermal?

We investigate the form of the momentum distribution function for protons and electrons in an advection-dominated accretion flow (ADAF). We show that for all accretion rates, Coulomb collisions are too inefficient to thermalize the protons. The proton distribution function is therefore determined by the viscous heating mechanism, which is unknown. The electrons, however, can exchange energy quite efficiently through Coulomb collisions and the emission and absorption of synchrotron photons. We find that for accretion rates greater than \sim 10^{-3} of the Eddington accretion rate, the electrons have a thermal distribution throughout the accretion flow. For lower accretion rates, the electron distribution function is determined by the electron's source of heating, which is primarily adiabatic compression. Using the principle of adiabatic invariance, we show that an adiabatically compressed collisionless gas maintains a thermal distribution until the particle energies become relativistic. We derive a new, non-thermal, distribution function which arises for relativistic energies and provide analytic formulae for the synchrotron radiation from this distribution. Finally, we discuss its implications for the emission spectra from ADAFs.Comment: 29 pages (Latex), 3 Figures. Submitted to Ap

The Radiopacity and Antimicrobial Properties of Different Radiopaque Double Antibiotic Pastes Used in Regenerative Endodontics

Introduction We evaluated the radiopacity and antibacterial properties of various concentrations of double antibiotic paste (DAP) containing barium sulfate (BaSO4) or zirconium oxide (ZrO2) radiopaque agents. Methods The radiopacity of 1, 10, and 25 mg/mL DAP containing 30% (w/v) BaSO4 or ZrO2, DAP-free radiopaque pastes, and commercially available radiopaque calcium hydroxide (Ca[OH]2) were evaluated according to ISO 6876/2001 with slight modifications (n = 6 per group). Dentin samples (n = 70) infected anaerobically for 3 weeks with bacterial biofilms obtained from a root canal of an immature tooth with pulpal necrosis were treated with similar experimental pastes or received no treatment (n = 7). After 1 week, the pastes were rinsed off, and biofilm disruption assays were conducted. To show the residual antibacterial effects, sterile dentin samples (n = 70) were pretreated for 1 week with the same pastes (n = 7). The pastes were rinsed off, and the samples were immersed in phosphate-buffered saline for 24 hours and infected anaerobically with the same bacterial biofilm mentioned earlier for 3 weeks before conducting biofilm disruption assays. Sterile dentin blocks were used in both antibacterial analyses as negative control groups (n = 7). Wilcoxon rank sum tests were used for statistical analyses. Results No tested concentrations of BaSO4 DAP or ZrO2 DAP showed significant differences from Ca(OH)2 in radiopacity. However, all tested concentrations of BaSO4 DAP, ZrO2 DAP, and Ca(OH)2 exhibited significant direct antibacterial effects. ZrO2 DAP at 1 mg/mL and Ca(OH)2 did not show significant residual antibacterial effects. Conclusions BaSO4 DAP at 1 mg/mL provided significantly superior residual antibacterial effects and comparable radiopacity with the commercially available Ca(OH)2

Gamma-ray Emission From Advection-Dominated Accretion Flows Around Black Holes: Application to the Galactic Center

We calculate the flux and spectrum of \gamma-rays emitted by a two-temperature advection-dominated accretion flow (ADAF) around a black hole. The \gamma-rays are from the decay of neutral pions produced through proton-proton collisions. We discuss both thermal and power-law distributions of proton energies and show that the \gamma-ray spectra in the two cases are very different. We apply the calculations to the \gamma-ray source, 2EG J1746-2852, detected by EGRET from the direction of the Galactic Center. We show that the flux and spectrum of this source are consistent with emission from an ADAF around the supermassive accreting black hole Sgr A^* if the proton distribution is a power-law. The model uses accretion parameters within the range made likely by other considerations. If this model is correct, it provides evidence for the presence of a two temperature plasma in Sgr A^*, and predicts \gamma-ray fluxes from other accreting black holes which could be observed with more sensitive detectors.Comment: 19 pages (Latex), 4 Figures. ApJ 486. Revised Tables and Figure