Group additivity calculation of the standard molal thermodynamic properties of aqueous amino acids, polypeptides and unfolded proteins as a function of temperature, pressure and ionization state

International audienceThermodynamic calculation of the chemical speciation of proteins and the limits of protein metastability affords a quantitative understanding of the biogeochemical constraints on the distribution of proteins within and among different organisms and chemical environments. These calculations depend on accurate determination of the ionization states and standard molal Gibbs free energies of proteins as a function of temperature and pressure, which are not generally available. Hence, to aid predictions of the standard molal thermodynamic properties of ionized proteins as a function of temperature and pressure, calculated values are given below of the standard molal thermodynamic properties at 25°C and 1 bar and the revised Helgeson-Kirkham-Flowers equations of state parameters of the structural groups comprising amino acids, polypeptides and unfolded proteins. Group additivity and correlation algorithms were used to calculate contributions by ionized and neutral sidechain and backbone groups to the standard molal Gibbs free energy (? G°), enthalpy (? H°), entropy (S°), isobaric heat capacity (C°P), volume (V°) and isothermal compressibility (?°T) of multiple reference model compounds. Experimental values of C°P, V° and ?°T at high temperature were taken from the recent literature, which ensures an internally consistent revision of the thermodynamic properties and equations of state parameters of the sidechain and backbone groups of proteins, as well as organic groups. As a result, ? G°, ? H°, S° C°P, V° and ?°T of unfolded proteins in any ionization state can be calculated up to T~-300°C and P~-5000 bars. In addition, the ionization states of unfolded proteins as a function of not only pH, but also temperature and pressure can be calculated by taking account of the degree of ionization of the sidechain and backbone groups present in the sequence. Calculations of this kind represent a first step in the prediction of chemical affinities of many biogeochemical reactions, as well as of the relative stabilities of proteins as a function of temperature, pressure, composition and intra- and extracellular chemical potentials of O2 and H2, NH3, H2PO4 and CO2

Chemolithotrophy in the continental deep subsurface: Sanford Underground Research Facility (SURF), USA

The deep subsurface is an enormous repository of microbial life. However, the metabolic capabilities of these microorganisms and the degree to which they are dependent on surface processes are largely unknown. Due to the logistical difficulty of sampling and inherent heterogeneity, the microbial populations of the terrestrial subsurface are poorly characterized. In an effort to better understand the biogeochemistry of deep terrestrial habitats, we evaluate the energetic yield of chemolithotrophic metabolisms and microbial diversity in the Sanford Underground Research Facility (SURF) in the former Homestake Gold Mine, SD, USA. Geochemical data, energetic modeling, and DNA sequencing were combined with principle component analysis to describe this deep (down to 8100 ft below surface), terrestrial environment. SURF provides access into an iron-rich Paleoproterozoic metasedimentary deposit that contains deeply circulating groundwater. Geochemical analyses of subsurface fluids reveal enormous geochemical diversity ranging widely in salinity, oxidation state (ORP 330 to −328 mV), and concentrations of redox sensitive species (e.g., Fe(2+) from near 0 to 6.2 mg/L and Σ S(2-) from 7 to 2778μg/L). As a direct result of this compositional buffet, Gibbs energy calculations reveal an abundance of energy for microorganisms from the oxidation of sulfur, iron, nitrogen, methane, and manganese. Pyrotag DNA sequencing reveals diverse communities of chemolithoautotrophs, thermophiles, aerobic and anaerobic heterotrophs, and numerous uncultivated clades. Extrapolated across the mine footprint, these data suggest a complex spatial mosaic of subsurface primary productivity that is in good agreement with predicted energy yields. Notably, we report Gibbs energy normalized both per mole of reaction and per kg fluid (energy density) and find the later to be more consistent with observed physiologies and environmental conditions. Further application of this approach will significantly expand our understanding of the deep terrestrial biosphere

Evidence for microbial mediation of subseafloor nitrogen redox processes at Loihi Seamount, Hawaii

© The Author(s), 2016. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 198 (2017): 131-150, doi:10.1016/j.gca.2016.10.029.The role of nitrogen cycling in submarine hydrothermal systems is far less studied than that of other biologically reactive elements such as sulfur and iron. In order to address this knowledge gap, we investigated nitrogen redox processes at Loihi Seamount, Hawaii, using a combination of biogeochemical and isotopic measurements, bioenergetic calculations and analysis of the prokaryotic community composition in venting fluids sampled during four cruises in 2006, 2008, 2009 and 2013. Concentrations of NH4+ were positively correlated to dissolved Si and negatively correlated to NO3-+NO2-, while NO2- was not correlated to NO3-+NO2-, dissolved Si or NH4+. This is indicative of hydrothermal input of NH4+ and biological mediation influencing NO2- concentrations. The stable isotope ratios of NO3- (d15N and d18O) was elevated with respect to background seawater, with d18O values exhibiting larger changes than corresponding d15N values, reflecting the occurrence of both production and reduction of NO3- by an active microbial community. d15N-NH4+ values ranged from 0‰ to +16.7‰, suggesting fractionation during consumption and potentially N-fixation as well. Bioenergetic calculations reveal that several catabolic strategies involving the reduction of NO3- and NO2- coupled to sulfide and iron oxidation could provide energy to microbes in Loihi fluids, while 16S rRNA gene sequencing of Archaea and Bacteria in the fluids reveals groups known to participate in denitrification and N-fixation. Taken together, our data support the hypothesis that microbes are mediating N-based redox processes in venting hydrothermal fluids at Loihi Seamount.This work was supported by the NSF Microbial Observatories program (MCB 0653265), the Gordon and Betty Moore Foundation (GBMF1609), NSF-OCE 0648287, the Center for Dark Energy Biosphere Investigations (C-DEBI) and the NASA Astrobiology Institute — Life Underground (NAI-LU). Sequence data was generated as part of the Alfred P. Sloan Foundation's ICoMM field project and the W. M. Keck Foundation

A Measure of Expectancies for Alcohol Analgesia: Preliminary Factor Analysis, Reliability, and Validity

Rates of alcohol consumption are substantially higher among persons with pain, and recent research has focused on elucidating bidirectional pain-alcohol effects. Expectancies for alcohol analgesia could influence the degree to which alcohol confers acute pain-relieving effects, and may amplify the propensity to respond to pain with drinking behavior. However, no validated measures of expectancies for alcohol analgesia are available. The goal of this project was to examine psychometric properties of a measure of Expectancies for Alcohol Analgesia (EAA) across two samples (current alcohol users with and without chronic pain). Study 1 included 200 moderate-to-heavy drinkers with no current acute/chronic pain (Mage = 33.4; 39% female) who were recruited for a primary laboratory study. Results indicated that the hypothesized single-factor structure of the EAA provided good model fit (Bollen-Stine bootstrap p = .17). The EAA also showed excellent internal consistency (α = .97), and scores were positively associated with average daily drinks, binge drinking frequency, and alcohol outcome expectancies (ps \u3c .01). As expected, EAA scores were not associated with participant height (p \u3e .05). Study 2 included 273 current alcohol users with chronic musculoskeletal pain (Mage = 32.9; 34% female) who completed an online survey of pain and substance use. Results of Study 2 further supported the single-factor structure (Bollen-Stine bootstrap p = .13), and internal consistency of the EAA was excellent (α = .97). EAA scores were positively associated with quantity/frequency of alcohol use, alcohol outcome expectancies, coping-related drinking motives, and pain severity (ps \u3c .01). EAA scores were not associated with height (p \u3e .05). Collectively, these findings provide initial support regarding the single-factor structure, reliability, and validity of the EAA. Examination of predictive utility and further validation will be important next steps

Pain-Related Anxiety as a Predictor of Early Lapse and Relapse to Cigarette Smoking

Pain-related anxiety has been positively associated with tobacco dependence, smoking motives, self-reported barriers to smoking cessation, and expectancies for negative affect reduction via smoking. Although emerging research suggests that pain-related anxiety may play a role in the maintenance of tobacco dependence, no previous work has examined pain-related anxiety as a predictor of smoking cessation outcomes. The goal of the current study was to test the hypothesis that pain-related anxiety would predict early lapse and relapse to cigarette smoking among a sample of 55 daily tobacco smokers who participated in an unaided cessation attempt (i.e., without psychosocial or pharmacological intervention). Pain-related anxiety was assessed at baseline using the PASS-20, which yields a total score that ranges from 0-100. Number of days to early lapse (i.e., any instance of smoking during the first 14 days post-quit) and early relapse (i.e., 7 consecutive days of smoking that began during the first 28 days post-quit) were assessed using timeline follow-back procedures. Cox regression analyses indicated that pain-related anxiety was a significant predictor of both early smoking lapse and relapse, such that for every one point increase on the PASS-20, the risk of early lapse increased by 3.7% and the risk of early relapse increased by 3.6%. These effects were evident above and beyond the variance accounted for by tobacco dependence, past four-week pain severity, anxiety sensitivity, and the presence of current Axis I psychopathology. Kaplan-Meier survival analyses further revealed that among early lapsers, greater pain-related anxiety predicted a more rapid trajectory to lapse. Pain-related anxiety was also shown to be a significant predictor of early lapse when the sample was limited to smokers who endorsed past four-week pain. These findings lend support to the notion that pain-related anxiety may contribute to the maintenance of tobacco dependence among smokers who experience varying levels of pain intensity

Consumption of recommended food groups among children from medically underserved communities

This cross-sectional study of 2 to 12 year olds living in medically underserved areas examined the proportion of children meeting the food group intake recommendations for fruits, vegetables, total grains, dairy, and meat/meat alternatives by age group and body weight status. Based on 24-hour recalls collected between July 2004 and March of 2005, mean food group intake and deviation from the recommended intake amount were determined (actual intake minus recommended intake). Measured weight and height were used to calculate body mass index z-scores using the Centers for Disease Control and Prevention (CDC) growth charts. Analyses were conducted for two age groups (2 to 5 and 6 to 12 year olds) (n=214), by weight status categories (underweight or healthy weight ( 95th percentile)), and repeated for the subset of children with biologically plausible reports. The majority of children lived in lowincome households. More 2 to 5 year olds met intake recommendations compared to 6 to 12 year olds. Overall, the proportion of children meeting the food group intake recommendations was low with the exception of the meat group, which was met by 52% to 93% of children. There was a positive association between the proportion of younger children meeting the fruits or total grains recommendation and increasing body weight. The data support the importance of community-level nutrition intervention programs to improve children's diet quality in low income, medically underserved areas and suggest that such interventions may help reduce the risk of obesity. Originally published Journal of the American Dietetic Association, Vol. 109, No. 4, Apr 200

Hazardous Alcohol Use Among Community-Dwelling Older Adults With Persistent or Recurrent Pain: Findings From the Health and Retirement Study.

BACKGROUND: Although pain and alcohol use are highly prevalent and associated with deleterious health outcomes among older adults, a paucity of literature has examined hazardous drinking among older adults with pain. We aimed to examine the prevalence of hazardous drinking among a nationally representative sample of older adults with persistent or recurrent pain. METHODS: We conducted cross-sectional analyses of data collected from the 2018 wave of the Health and Retirement Study. Participants included 1  549 community-dwelling adults aged ≥65 with persistent or recurrent pain (ie, clinically significant pain present at 2 consecutive survey waves). RESULTS: More than one-quarter of older adults with persistent or recurrent pain reported regular alcohol use (≥weekly), nearly half of whom reported hazardous patterns of drinking. Specifically, 32% reported excessive drinking (ie, >2 drinks per day for older men; >1 drink per day for older women), and 22% reported binge drinking (ie, ≥4 drinks on one occasion). Exploratory analyses revealed a high prevalence of hazardous drinking among the subsample of older adults who used opioids (47%). CONCLUSIONS: Hazardous alcohol use-including both excessive and binge drinking-is common among older adults with persistent or recurrent pain, including those who take opioids. Given that hazardous drinking can complicate pain management and increase the risk for adverse opioid effects (eg, overdose), the current findings underscore the importance of assessing and addressing hazardous patterns of alcohol use among older adults with persistent or recurrent pain

Double Contrast Arthrography of the Knee

Arthrography is a safe and relatively simple diagnostic procedure which provides an accurate and graphic preoperative means of defining pathology of the knee. In those cases where the expeditious evaluation and diagnosis of knee injury are of prime importance, ie, the athlete and industrial compensation case, arthrography provides a significant contribution. The clinical pathological features, salient anatomy and technic of study of internal derangements of the knee are discussed. Selected double contrast arthrograms illustrate normal and abnormal findings. Arthrotomies were performed in 20 of the 32 patients in this study with a positive arthrogram-arthrotomy correlation of 85%