Gas Phase Infrared Spectroscopy of Glycolipids

Carbohydrates and lipids are not only energy sources and structural components of cells but fulfill very diverse and important roles in a multitude of cellular processes. The combination of a carbohydrate and a lipid linked via a glycosidic bond yields a glycolipid. Glycolipids occur in all kinds of organisms where they constitute major components of cell membranes, mediate cell-cell interactions and modulate immune responses. Their biological activities are highly dependent on their exact three-dimensional structures; however, the elucidation of glycolipid structures is inherently challenging due to the non-template-driven regio- and stereoselective synthesis of the carbohydrate and additional variations of the lipid moiety, such as length, saturation and hydroxylation. The modular biosynthesis of glycolipids generates many different and often isomeric combinations of glycans and lipids, which are not always distinguishable by standard analytical workflows based on liquid chromatography-mass spectrometry. The structural analysis of isomeric glycolipids thus requires orthogonal techniques yielding complementary information. In some cases, ion mobility spectrometry can be used to distinguish isomers based on their different cross sections in the gas phase. Another promising structure-sensitive technique is cryogenic gas phase infrared spectroscopy, which falls under the term action spectroscopy and yields highly resolved, reproducible IR spectra of isolated ions in the clean gas phase environment. In this work, sets of isomeric glycolipids were systematically investigated using ion mobility-mass spectrometry and cryogenic gas phase IR spectroscopy in helium nano- droplets. The obtained IR spectra of various isomeric glycosphingolipids bearing different monosaccharide headgroups are diagnostic for both the type of monosaccharide and the anomeric configuration because of very characteristic and reproducible absorption bands in the fingerprint region (1000–1150 cm-1). A more complex trisaccharide headgroup still yields a well-resolved IR fingerprint. The influence of the lipid part was examined by comparing IR spectra of glycolipids bearing the same headgroup but a different sphingoid base or a diacylglycerol. The exchange of phytosphingosine for sphingosine does not alter the fingerprint region significantly but influences the intensity of the amine bending vibration, whereas the introduction of a diacylglycerol changes the whole spectrum. The data show that cryogenic gas phase IR spectroscopy is a powerful technique to distinguish glycolipids bearing isomeric glycans up to a certain size, anomeric configurations and also subtle variations in the lipid moiety. Furthermore, the applicability of IR spectroscopy to distinguish double bond isomers was tested on synthetic derivatives of 1-deoxysphingosine. Depending on the position and configuration of the C C double bond, distinct N H bending modes of the protonated amine are observed. Gas phase IR spectroscopy could thus fill a gap in lipidomics, where lipid double bond isomers still pose a major challenge

Conscientiousness, hair cortisol concentration, and health behaviour in older men and women

Conscientious is associated with greater longevity and other favourable health outcomes, but the processes underlying these links are poorly understood. Health behaviours such as physical activity and avoidance of smoking and excessive alcohol consumption may contribute, but direct associations with neuroendocrine and inflammatory processes may also be relevant. We tested the associations between conscientiousness and hair cortisol concentration in 2318 older men and women (mean age 66.2 years) from the English Longitudinal Study of Ageing. Conscientiousness was positively associated with physical activity and fruit and vegetable consumption, and negatively related to alcohol intake, sedentary behaviour, body mass index and depressive symptoms (all p<0.001). We found an inverse association between conscientiousness and hair cortisol concentration that was independent of age, sex, education and wealth (β=-0.053, p=0.012), and the relationship remained significant with additional adjustment for health behaviour and depressive symptoms (β=-0.048, p=0.025). The observation that greater conscientiousness was correlated with lower hair cortisol indicates that this trait might impact central nervous regulation of hypothalamic-pituitary-adrenocortical function, with effects that are possibly advantageous for health

Hair cortisol and adiposity in a population-based sample of 2,527 men and women aged 54 to 87 years

OBJECTIVE: Chronic cortisol exposure is hypothesized to contribute to obesity. This study examined associations between hair cortisol concentrations, a novel indicator of long-term cortisol exposure, and adiposity in a large population-based sample. METHODS: Data were from 2,527 men and women aged 54 and older (98% white British) participating in the English Longitudinal Study of Ageing. Hair cortisol concentrations were determined from the scalp-nearest 2 cm hair segment, and height, weight, and waist circumference were objectively measured. Covariates included age, sex, socioeconomic status, smoking status, diabetes, and arthritis. RESULTS: In cross-sectional analyses, hair cortisol concentrations were positively correlated with weight (r = 0.102, P < 0.001), BMI (r = 0.101, P < 0.001), and waist circumference (r = 0.082, P = 0.001) and were significantly elevated in participants with obesity (BMI ≥30 kg/m(2) ) (F = 6.58, P = 0.001) and raised waist circumference (≥102 cm in men, ≥88 cm in women) (F = 4.87, P = 0.027). Hair cortisol levels were also positively associated with the persistence of obesity (F = 12.70, P < 0.001), evaluated in retrospect over 4 years. CONCLUSIONS: Chronic exposure to elevated cortisol concentrations, assessed in hair, is associated with markers of adiposity and with the persistence of obesity over time

Perceived weight discrimination and chronic biochemical stress: A population-based study using cortisol in scalp hair

Objective: There is increasing evidence for weight-based discrimination against persons with obesity. This study aimed to examine the physiological impact of perceived weight discrimination on cortisol in hair, an indicator of chronic stress exposure. - - Methods: Data were from 563 nonsmoking individuals with obesity (body mass index, BMI ≥30 kg/m2) participating in the English Longitudinal Study of Ageing. Experiences of discrimination were reported via questionnaire, and hair cortisol concentrations were determined from the scalp-nearest 2-cm hair segment. Height and weight were objectively measured. ANCOVAs tested associations between perceived weight discrimination and hair cortisol concentration overall and by degree of obesity. All analyses were adjusted for age, sex, ethnicity, socioeconomic status, and BMI. - - Results: Mean hair cortisol concentrations were 33% higher in those who had experienced weight discrimination than those who had not (mean log pg/mg 1.241 vs. 0.933, F = 12.01, P = 0.001). The association between weight discrimination and hair cortisol was particularly pronounced in individuals with severe (class II/III) obesity (1.402 vs. 0.972, F = 11.58, P = 0.001). - - Conclusions: Weight discrimination is associated with the experience of stress at a biological level. Chronic exposure to elevated levels of cortisol may play a role in generating a vicious circle of weight gain and discrimination and contribute to obesity-associated health conditions

Automated Satellite-Based Landslide Identification Product for Nepal

Landslide event inventories are a vital resource for landslide susceptibility and forecasting applications. However, landslide inventories can vary in accuracy, availability, and timeliness as a result of varying detection methods, reporting, and data availability. This study presents an approach to use publicly available satellite data and open source software to automate a landslide detection process called the Sudden Landslide Identification Product (SLIP). SLIP utilizes optical data from the Landsat 8 OLI sensor, elevation data from the Shuttle Radar Topography Mission (SRTM), and precipitation data from the Global Precipitation Measurement (GPM) mission to create a reproducible and spatially customizable landslide identification product. The SLIP software applies change detection algorithms to identify areas of new bare-earth exposures that may be landslide events. The study also presents a precipitation monitoring tool that runs alongside SLIP called the Detecting Real-time Increased Precipitation (DRIP) model that helps identify the timing of potential landslide events detected by SLIP. Using SLIP and DRIP together, landslide detection is improved by reducing problems related to accuracy, availability, and timeliness that are prevalent in the state-of-the-art of landslide detection. A case study and validation exercise was performed in Nepal for images acquired between 2014 and 2015. Preliminary validation results suggest 56% model accuracy, with errors of commission often resulting from newly cleared agricultural areas. These results suggest that SLIP is an important first attempt in an automated framework that can be used for medium resolution regional landslide detection, although it requires refinement before being fully realized as an operational tool

Controlling the uncontrolled: Are there incidental experimenter effects on physiologic responding?

The degree to which experimenters shape participant behavior has long been of interest in experimental social science research. Here, we extend this question to the domain of peripheral psychophysiology, where experimenters often have direct, physical contact with participants, yet researchers do not consistently test for their influence. We describe analytic tools for examining experimenter effects in peripheral physiology. Using these tools, we investigate nine data sets totaling 1,341 participants and 160 experimenters across different roles (e.g., lead research assistants, evaluators, confederates) to demonstrate how researchers can test for experimenter effects in participant autonomic nervous system activity during baseline recordings and reactivity to study tasks. Our results showed (a) little to no significant variance in participants' physiological reactivity due to their experimenters, and (b) little to no evidence that three characteristics of experimenters that are well known to shape interpersonal interactions-status (using five studies with 682 total participants), gender (using two studies with 359 total participants), and race (in two studies with 554 total participants)-influenced participants' physiology. We highlight several reasons that experimenter effects in physiological data are still cause for concern, including the fact that experimenters in these studies were already restricted on a number of characteristics (e.g., age, education). We present recommendations for examining and reducing experimenter effects in physiological data and discuss implications for replication

Associations between hair cortisol concentration, income, income dynamics and status incongruity in healthy middle-aged women.

A body of research demonstrates that financial disadvantage is associated with general health inequalities and higher mortality rates. Most studies make use of cross-sectional analyses, although income can also be viewed as a dynamic concept. The use of endocrine-markers as proxies for health can provide information about the pathways involved in these associations. Hair cortisol analysis has been developed as a method for assessing sustained cortisol output as it provides an estimate of cumulative cortisol secretion over a prolonged time. The present study assessed income and income trajectory over a 4-year period in 164 working women (aged 26-65) in relation to hair cortisol in a longitudinal design. A negative association between hair cortisol and concurrent income was found (p=0.025) and hair cortisol and changes in income over 4 years (p<0.001), after adjustment for age, BMI, smoking status, hair treatment and country. Status incongruity, a mismatch between educational status and income group, was related to higher cortisol levels compared with status congruity (p=0.009). These findings suggest that psychoneuroendocrinological pathways might partially explain the relationship between lower socio-economic status and adverse health outcomes. Future longitudinal research using hair cortisol analysis is warranted to clarify the time course of social mobility in relation to long-term cortisol, to investigate other underlying psychosocial factors implicated in these associations, and to determine the exact health implications of the neuroendocrine perturbations in individuals with limited economic resources