CNDO Calculations On The Structure Of A Liquid Sodium Carboxylate-carboxylic Acid Compound

The molecular interactions in a carboxylic acid/sodium carboxylate compound which is a liquid at room temperature were calculated using a CNDO/2 approach. The calculations gave results distinguishing the energy for different conformations in the molecular compound. The maximum binding energy was found for a structure in which the four acids were bridging with a hydrogen bond from the acid OH group to the carboxylate group and the acid carbonyl groups forming a ligand bond to the carboxylate sodium ion. © 1979 Academic Press, Inc

Intermolecular Interactions For Phosphatidyl Choline And Phosphatidyl Ethanolamine

Intermolecular interaction between pairs of methylphosphocholine (MPC) and methylphosphoethanolamine were calculated using an extended CNDO/2 program. Experimentally determined conformations were used for the ethanolamine and choline groups. In the methylphosphocholine the major interaction was intramolecular, involving the phosphate ester-choline groups, while in the ethanolamine the maximum attraction was intermolecular between the ethanolamine and the phophate ester of a neighboring molecule(s). © 1983

Immunosenescence in wild animals:Meta-analysis and outlook

Immunosenescence, the decline in immune defense with age, is an important mortality source in elderly humans but little is known of immunosenescence in wild animals. We systematically reviewed and meta-analysed evidence for age-related changes in immunity in captive and free-living populations of wild species (321 effect sizes in 62 studies across 44 species of mammals, birds and reptiles). As in humans, senescence was more evident in adaptive (acquired) than innate immune functions. Declines were evident for cell function (antibody response), the relative abundance of naive immune cells and an in vivo measure of overall immune responsiveness (local response to phytohaemagglutinin injection). Inflammatory markers increased with age, similar to chronic inflammation associated with human immunosenescence. Comparisons across taxa and captive vs free-living animals were difficult due to lack of overlap in parameters and species measured. Most studies are cross-sectional, which yields biased estimates of age-effects when immune function co-varies with survival. We therefore suggest longitudinal sampling approaches, and highlight techniques from human cohort studies that can be incorporated into ecological research. We also identify avenues to address predictions from evolutionary theory and the contribution of immunosenescence to age-related increases in disease susceptibility and mortality

Indirect Dark Matter Detection from Dwarf Satellites: Joint Expectations from Astrophysics and Supersymmetry

We present a general methodology for determining the gamma-ray flux from annihilation of dark matter particles in Milky Way satellite galaxies, focusing on two promising satellites as examples: Segue 1 and Draco. We use the SuperBayeS code to explore the best-fitting regions of the Constrained Minimal Supersymmetric Standard Model (CMSSM) parameter space, and an independent MCMC analysis of the dark matter halo properties of the satellites using published radial velocities. We present a formalism for determining the boost from halo substructure in these galaxies and show that its value depends strongly on the extrapolation of the concentration-mass (c(M)) relation for CDM subhalos down to the minimum possible mass. We show that the preferred region for this minimum halo mass within the CMSSM with neutralino dark matter is ~10^-9-10^-6 solar masses. For the boost model where the observed power-law c(M) relation is extrapolated down to the minimum halo mass we find average boosts of about 20, while the Bullock et al (2001) c(M) model results in boosts of order unity. We estimate that for the power-law c(M) boost model and photon energies greater than a GeV, the Fermi space-telescope has about 20% chance of detecting a dark matter annihilation signal from Draco with signal-to-noise greater than 3 after about 5 years of observation

El Niño Southern Oscillation signal in a new East Antarctic ice core, Mount Brown South

Abstract. Paleoclimate archives, such as high-resolution ice core records, provide a means to investigate long-term (multi-centennial) climate variability. Until recently, the Law Dome (Dome Summit South) ice core record remained one of few long-term high-resolution records in East Antarctica. A new ice core drilled in 2017/2018 at Mount Brown South, approximately 1000 km west of Law Dome, provides an additional high-resolution record that will likely span the last millennium in the Indian Ocean sector of East Antarctica. Here, we compare snowfall accumulation rates and sea salt concentrations in the upper portion (~21 m) of the Mount Brown South record, and an updated Law Dome record over the period 1975–2016. Annual sea salt concentrations from the Mount Brown South record preserves a stronger signal for the El Niño-Southern Oscillation (ENSO; in austral winter and spring, r = 0.521, p r = −0.387, p = 0.018, Niño 3.4). The Mount Brown South and Law Dome ice cores record inverse signals for the ENSO, suggesting the occurrence of distinct moisture and aerosol intrusions. We suggest that ENSO-related sea surface temperature anomalies in the equatorial Pacific drive atmospheric teleconnections in the southern mid-latitudes. These anomalies are associated with a weakening (strengthening) of regional westerly winds to the north of Mount Brown South that corresponds to years of low (high) sea salt deposition at Mount Brown South during La Niña (El Niño) events. The Mount Brown South annual sea salt record when complete will offer a new proxy record for reconstructions of the ENSO over the recent millennium, along with improved understanding of regional atmospheric variability in the southern Indian Ocean in addition to that derived from Law Dome

The Physics of Star Cluster Formation and Evolution

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe

Conformation Of The Lecithin Molecule With Attached Water Molecules

CNDO/2 studies on the conformation of the α chain of lecithin indicated a strong preference for a gauche-gauche arrangement about the phosphodiester group. Folding the α chain about[Figure not available: see fulltext.] and α4 was energetically very favorable. Hydration of the same segment revealed three levels of water-binding energies. The ion-dipole interactions of water and the choline moiety were energetically non-substantial. In contrast, binding of water to the unesterified phosphate oxygens produced the highest enthalpies. Attachment of water to the esterified phosphate oxygens or the ester oxygens of the β chain resulted in intermediate binding strengths. By investigating complete incorporation of nine water molecules into a chosen lipid structure, a plausible lecithin-water geometry was deduced for a liquid crystalline system. © 1981 Forum Press, Inc

A genetic basis for functional hypothalamic amenorrhea.

Background: Functional hypothalamic amenorrhea is a reversible form of gonadotropin-releasing hormone (GnRH) deficiency commonly triggered by stressors such as excessive exercise, nutritional deficits, or psychological distress. Women vary in their susceptibility to inhibition of the reproductive axis by such stressors, but it is unknown whether this variability reflects a genetic predisposition to hypothalamic amenorrhea. We hypothesized that mutations in genes involved in idiopathic hypogonadotropic hypogonadism, a congenital form of GnRH deficiency, are associated with hypothalamic amenorrhea. Methods: We analyzed the coding sequence of genes associated with idiopathic hypogonadotropic hypogonadism in 55 women with hypothalamic amenorrhea and performed in vitro studies of the identified mutations. Results: Six heterozygous mutations were identified in 7 of the 55 patients with hypothalamic amenorrhea: two variants in the fibroblast growth factor receptor 1 gene FGFR1 (G260E and R756H), two in the prokineticin receptor 2 gene PROKR2 (R85H and L173R), one in the GnRH receptor gene GNRHR (R262Q), and one in the Kallmann syndrome 1 sequence gene KAL1 (V371I). No mutations were found in a cohort of 422 controls with normal menstrual cycles. In vitro studies showed that FGFR1 G260E, FGFR1 R756H, and PROKR2 R85H are loss-of-function mutations, as has been previously shown for PROKR2 L173R and GNRHR R262Q. Conclusions: Rare variants in genes associated with idiopathic hypogonadotropic hypogonadism are found in women with hypothalamic amenorrhea, suggesting that these mutations may contribute to the variable susceptibility of women to the functional changes in GnRH secretion that characterize hypothalamic amenorrhea. Our observations provide evidence for the role of rare variants in common multifactorial disease. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others; ClinicalTrials.gov number, NCT00494169.

Incident diabetes in survivors of critical illness and mechanisms underlying persistent glucose intolerance: a prospective cohort study

OBJECTIVES:Stress hyperglycemia occurs in critically ill patients and may be a risk factor for subsequent diabetes. The aims of this study were to determine incident diabetes and prevalent prediabetes in survivors of critical illness experiencing stress hyperglycemia and to explore underlying mechanisms. DESIGN:This was a prospective, single center, cohort study. At admission to ICU, hemoglobin A1c was measured in eligible patients. Participants returned at 3 and 12 months after ICU admission and underwent hemoglobin A1c testing and an oral glucose tolerance test. Blood was also collected for hormone concentrations, whereas gastric emptying was measured via an isotope breath test. β-cell function was modeled using standard techniques. SETTING:Tertiary-referral, mixed medical-surgical ICU. PATIENTS:Consecutively admitted patients who developed stress hyperglycemia and survived to hospital discharge were eligible. MEASUREMENTS AND MAIN RESULTS:Consent was obtained from 40 patients (mean age, 58 yr [SD, 10], hemoglobin A1c 36.8 mmol/mol [4.9 mmol/mol]) with 35 attending the 3-month and 26 the 12-month visits. At 3 months, 13 (37%) had diabetes and 15 (43%) had prediabetes. At 12 months, seven (27%) participants had diabetes, whereas 11 (42%) had prediabetes. Mean hemoglobin A1c increased from baseline during the study: +0.7 mmol/mol (-1.2 to 2.5 mmol/mol) at 3 months and +3.3 mmol/mol (0.98-5.59 mmol/mol) at 12 months (p = 0.02). Gastric emptying was not significantly different across groups at either 3 or 12 months. CONCLUSIONS:Diabetes and prediabetes occur frequently in survivors of ICU experiencing stress hyperglycemia. Based on the occurrence rate observed in this cohort, structured screening and intervention programs appear warranted.Palash Kar, Mark P. Plummer, Yasmine Ali Abdelhamid, Emma J. Giersch, Matthew J. Summers, Luke M. Weinel ... et al