Association between meatless diet and depressive episodes: A cross-sectional analysis of baseline data from the longitudinal study of adult health (ELSA-Brasil).

BACKGROUND: The association between vegetarianism and depression is still unclear. We aimed to investigate the association between a meatless diet and the presence of depressive episodes among adults. METHODS: A cross-sectional analysis was performed with baseline data from the ELSA-Brasil cohort, which included 14,216 Brazilians aged 35 to 74 years. A meatless diet was defined from in a validated food frequency questionnaire. The Clinical Interview Schedule-Revised (CIS-R) instrument was used to assess depressive episodes. The association between meatless diet and presence of depressive episodes was expressed as a prevalence ratio (PR), determined by Poisson regression adjusted for potentially confounding and/or mediating variables: sociodemographic parameters, smoking, alcohol intake, physical activity, several clinical variables, self-assessed health status, body mass index, micronutrient intake, protein, food processing level, daily energy intake, and changes in diet in the preceding 6 months. RESULTS: We found a positive association between the prevalence of depressive episodes and a meatless diet. Meat non-consumers experienced approximately twice the frequency of depressive episodes of meat consumers, PRs ranging from 2.05 (95%CI 1.00-4.18) in the crude model to 2.37 (95%CI 1.24-4.51) in the fully adjusted model. LIMITATIONS: The cross-sectional design precluded the investigation of causal relationships. CONCLUSIONS: Depressive episodes are more prevalent in individuals who do not eat meat, independently of socioeconomic and lifestyle factors. Nutrient deficiencies do not explain this association. The nature of the association remains unclear, and longitudinal data are needed to clarify causal relationship.

Water Behaviour: glass transition in hyperquenched water?

It has been unclear whether amorphous glassy water heated to around 140-150 K remains glassy until it crystallizes or whether instead it turns into a supercooled and very viscous liquid. Yue and Angell compare the behaviour of glassy water under these conditions to that of hyperquenched inorganic glasses, and claim that water stays glassy as it heats up to its crystallization point; they also find a 'hidden' glass-to-liquid transition at about 169 K. Here we use differential scanning calorimetry (DSC) heating to show that hyperquenched water deposited at 140 K behaves as an ultraviscous liquid, the limiting structure of which depends on the cooling rate--as predicted by theoretical analysis of the liquid-to-glass transition. Our findings are consistent with a glass-to-liquid transition-onset temperature (T(g)) in the region of 136 K (refs 3,4), and they indicate that measurements of the liquid's properties may clarify the anomalous properties of supercooled water.

Raman spectroscopic study of the phase transition of amorphous to crystalline beta-carbonic acid.

What's the matter? The laboratory Raman spectra for carbonic acid (H(2)CO(3)), both for the beta-polymorph and its amorphous state, are required to detect carbonic acid on the surface of the pole caps of Mars in 2009, when the Mars Microbeam Raman Spectrometer lands on the planet. The picture shows a martian crater with ice of unknown composition, possibly containing carbonic acid (image adapted from DLR, with permission from ESA, DLR, and FU Berlin--G. Neukum).

Radicals produced by gamma-irradiation of hyperquenched glassy water containing 2'-deoxyguanosine-5'-monophosphate.

Hyperquenched glassy water (HGW) has been suggested as the best model for liquid water, to be used in low-temperature studies of indirect radiation effects on dissolved biomolecules (Bednarek et al. J. Am. Chem. Soc. 1996, 118, 9387). In the present work, these effects are examined by X-band electron spin resonance spectroscopy (ESR) in gamma-irradiated HGW matrix containing 2'-deoxyguanosine-5'-monophosphate. Analysis of the complex ESR spectra indicates that, in addition to OH(*) and HO2(*) radicals generated by water radiolysis, three species are trapped at 77 K:(i) G(C8)H(*) radical, the H-adduct to the double bond at C8; (ii) G(- *) radical anion, the product of electron scavenging by the aromatic ring of the base; and (iii) dR(-H)(*) radicals formed by H abstraction from the sugar moiety, predominantly at the C'5 position. We discuss the yields of the radicals, their thermal stability and transformations, as well as the effect of photobleaching. This study confirms our earlier suggestion that in HGW the H atom addition/abstraction products are created at 77 K in competition with HO2(*) radicals, in a concerted process following ionization of water molecule at L-type defect sites of the H-bonded matrix. The lack of OH(*) reactivity toward the solute suggests that the H-bonded structure in HGW is much more effective in recombining OH(*) radicals than that of aqueous glasses obtained from highly concentrated electrolyte solutions. Furthermore, complementary experiments for the neat matrix have provided evidence that HO2(*) radicals are not the product of H atom reaction with molecular oxygen, possibly generated by ultrasounds used in the process of sample preparation.

Novel method to detect the volumetric glass --> liquid transition at high pressures: glycerol as a test case.

We report a novel method of detecting the glass --> liquid transition at high pressures, which comprises measuring the relative volume change incurred upon heating glassy samples into the liquid state. We show data on glycerol in the pressure range 0.050-1.00 GPa to demonstrate the viability of the method. The reversible glass --> liquid transition is observed by means of a kink in the relative volume change on heating the sample isobarically, which is attributed to the glass --> liquid transition temperature Tg. This kink can only be observed in the second and subsequent heating cycles since it is superposed by a compaction in the first heating cycle. The isobaric thermal expansivity beta, which is closely related to the first derivative of this curve, shows the features expected for a glass --> liquid transition, including a sharp rise of beta(glass) in a narrow temperature interval to beta(viscous liquid) and an accompanying overshoot effect. Both Tg and the size of the overshoot effect vary in accordance with theory upon changing the ratio of cooling to heating rates. From the shape of this curve the onset, inflection, overshoot peak, and endpoint of the glass --> liquid transition can be extracted, which can be employed to calculate the reduced glass transition width as a measure for the fragility of the liquid. Comparison with literature data allows quantifying the accuracy of the liquid's thermal expansivity beta to be at least +/-10%, while the error in beta is significantly larger for the expansivity of the glassy state. The reproducibility of the glass --> liquid transition temperature Tg is better than +/-2 K. Our glycerol data confirms literature studies showing a nonlinear increase of Tg with increasing pressure (approximately 35 K/GPa on average), which is accompanied by an increase in fragility.

Cancer metabolism: the volatile signature of glycolysis-in vitro model in lung cancer cells.

Discovering the volatile signature of cancer cells is an emerging approach in cancer research, as it may contribute to a fast and simple diagnosis of tumors in vivo and in vitro. One of the main contributors to such a volatile signature is hyperglycolysis, which characterizes the cancerous cell. The metabolic perturbation in cancer cells is known as the Warburg effect; glycolysis is preferred over oxidative phosphorylation (OXPHOS), even in the presence of oxygen. The precise mitochondrial alterations that underlie the increased dependence of cancer cells on aerobic glycolysis for energy generation have remained a mystery. We aimed to profile the volatile signature of the glycolysis activity in lung cancer cells. For that an in vitro model, using lung cancer cell line cultures (A549, H2030, H358, H322), was developed. The volatile signature was measured by proton transfer reaction mass spectrometry under normal conditions and glycolysis inhibition. Glycolysis inhibition and mitochondrial activity were also assessed by mitochondrial respiration capacity measurements. Cells were divided into two groups upon their glycolytic profile (PET positive and PET negative). Glycolysis blockade had a unique characteristic that was shared by all cells. Furthermore, each group had a characteristic volatile signature that enabled us to discriminate between those sub-groups of cells. In conclusion, lung cancer cells may have different subpopulations of cells upon low and high mitochondrial capacity. In both groups, glycolysis blockade induced a unique volatile signature.

Real-time metabolic monitoring with proton transfer reaction mass spectrometry.

We analysed the time evolution of several volatile organic compounds formed by the catabolism of ingested isotope-labelled ethanol using real-time breath gas analysis with proton-transfer-reaction mass spectrometry. Isotope labelling allowed distinguishing the emerging volatile metabolites from their naturally occurring, highly abundant counterparts in the human breath. Due to an extremely low detection limit of the employed technologies in the parts per trillion per volume range, it was possible to detect the emerging metabolic products in exhaled breath within ∼10 min after oral ingestion of isotope-labelled ethanol. We observed that ethanol was in part transformed into deuterated acetone and isoprene, reflecting the different fates of activated acetic acid (acetyl-coenzyme A), formed in ethanol metabolism. Using ethanol as a model clearly demonstrated the value of the here presented technique for the search for volatile markers for metabolic disorders in the exhaled breath and its potential usefulness in the diagnosis and monitoring of such diseases.

First observation of a potential non-invasive breath gas biomarker for kidney function.

We report on the search for low molecular weight molecules-possibly accumulated in the bloodstream and body-in the exhaled breath of uremic patients with kidney malfunction. We performed non-invasive analysis of the breath gas of 96 patients shortly before and several times after kidney transplantation using proton-transfer-reaction mass spectrometry (PTR-MS), a very sensitive technique for detecting trace amounts of volatile organic compounds. A total of 642 individual breath analyses which included at least 41 different chemical components were carried out. Correlation analysis revealed one particular breath component with a molecular mass of 114 u (unified atomic mass units) that clearly correlated with blood serum creatinine, which is the currently accepted marker for assessing the function of the kidney. In particular, daily urine production showed good correlation with the identified breath marker. An independent set of seven samples taken from three patients at the onset of dialysis and three controls with normal kidney function confirmed a significant difference in concentration between patients and controls for a compound with a molecular mass of 114.1035 u using high mass resolving proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). A chemical composition of C7H14O was derived for the respective component. Fragmentation experiments on the same samples using proton-transfer-reaction triple-quadrupole tandem mass spectrometry (PTR-QqQ-MS) suggested that this breath marker is a C7-ketone or a branched C7-aldehyde. Non-invasive real-time monitoring of the kidney function via this breath marker could be a possible future procedure in the clinical setting.

Cryoflotation: densities of amorphous and crystalline ices.

We present an experimental method aimed at measuring mass densities of solids at ambient pressure. The principle of the method is flotation in a mixture of liquid nitrogen and liquid argon, where the mixing ratio is varied until the solid hovers in the liquid mixture. The temperature of such mixtures is in the range of 77-87 K, and therefore, the main advantage of the method is the possibility of determining densities of solid samples, which are instable above 90 K. The accessible density range (~0.81-1.40 g cm(-3)) is perfectly suitable for the study of crystalline ice polymorphs and amorphous ices. As a benchmark, we here determine densities of crystalline polymorphs (ices I(h), I(c), II, IV, V, VI, IX, and XII) by flotation and compare them with crystallographic densities. The reproducibility of the method is about ±0.005 g cm(-3), and in general, the agreement with crystallographic densities is very good. Furthermore, we show measurements on a range of amorphous ice samples and correlate the density with the d spacing of the first broad halo peak in diffraction experiments. Finally, we discuss the influence of microstructure, in particular voids, on the density for the case of hyperquenched glassy water and cubic ice samples prepared by deposition of micrometer-sized liquid droplets.

Buffered end-tidal (BET) sampling-a novel method for real-time breath-gas analysis.

We present a novel method for real-time breath-gas analysis using mass-spectrometric techniques: buffered end-tidal (BET) on-line sampling. BET has several advantages over conventional direct on-line sampling where the subject inhales and exhales through a sampling tube. In our approach, a single exhalation is administered through a tailored tube in which the end-tidal fraction of the breath-gas sample is buffered. This increases sampling time by an order of magnitude to several seconds, improving signal quality and reducing the total measurement time per test subject. Furthermore, only one exhalation per minute is required for sampling and the test subject can otherwise maintain a normal breathing pattern, thereby reducing the risk of hyperventilation. To validate our new BET sampling method we conducted comparative measurements with direct on-line sampling using proton-transfer-reaction mass spectrometry. We find excellent agreement in measured acetone and acetonitrile concentrations. High variability observed in breath-by-breath isoprene concentrations is attributed to differences in exhalation depth and influences of hyperventilation on end-tidal concentrations.

Amorphous ice: stepwise formation of very-high-density amorphous ice from low-density amorphous ice at 125 K.

On compressing low-density amorphous ice (LDA) at 125 K up to 1.6 GPa, two distinct density steps accompanied by heat evolution are observable in pressure-density curves. Samples recovered to 77 K and 1 bar after the first and second steps show the x-ray diffraction pattern of high-density amorphous ice (HDA) and very HDA (VHDA), respectively. The compression of the once formed HDA takes place linearly in density up to 0.95 GPa, where nonlinear densification and HDA --> VHDA conversion is initiated. This implies a stepwise formation process LDA--> HDA --> VHDA at 125 K, which is to the best of our knowledge the first observation of a stepwise amorphous-amorphous-amorphous transformation sequence. We infer that the relation of HDA and VHDA is very similar to the relation between LDA and HDA except for a higher activation barrier between the former. We discuss the two options of thermodynamic versus kinetic origin of the phenomenon.

Liquid-like relaxation in hyperquenched water at < or = 140 K.

Micrometre-sized water droplets were hyperquenched on a solid substrate held at selected temperatures between 150 and 77 K. These samples were characterized by differential scanning calorimetry (DSC) and X-ray diffraction. 140 K is the upper temperature limit to obtain mainly amorphous samples on deposition within 16-37 min. DSC scans of glassy water prepared at 140 K exhibit on heating an endothermic step assignable to glass --> liquid transition, with an onset temperature (T(g)) of 136 +/- 2 K on heating at 30 K min(-1). For T(g) of approximately 136 K, water relaxes during deposition at 140 K for 16 min, moving towards metastable equilibrium. The apparent increase in heat capacity (deltaC(p)) depends, for a given rate of heating, on the rate of prior cooling, and a so-called overshoot develops. 140 K deposits cooled at a rate of 5, 2 or 0.2 K min(-1) show on subsequent reheating at a rate of 30 K min(-1) deltaC(p) values of 0.7, 1.1 and 1.7 J K(-1) mol(-1). This is consistent with liquid-like relaxation at 140 K, and it indicates that different limiting structures are obtained. When these 140 K deposits are in addition annealed at 130 K for 90 min, after slow-cooling at 5, 2 or 0.2 K min(-1), their deltaC(p) values on subsequent reheating are similar to those of hyperquenched glassy water (HGW) deposits made at 77 K and annealed at 130 K. Thus, the previous deltaC(p) value of 1.6 J K(-1) mol(-1) obtained with glassy water samples annealed at 130 K (A. Hallbrucker, E. Mayer and G. P. Johari, Philos. Mag. B, 1989, 60, 179) must be an upper-bound limit because it contains a contribution from an overshoot. The T(g) value of 140 K deposits, which had relaxed during deposition towards metastable equilibrium, is within experimental error the same as that of 140 K deposits annealed in addition at 130 K. This contradicts Yue and Angell's (Y. Yue and C. Angell, Nature, 2004, 427, 717) claim for assigning the endothermic step to a sub-T(g) peak or a "shadow" T(g). Our new data further support the proposed fragile-to-strong transition on cooling liquid water from ambient temperature into the deeply supercooled and glassy state. We also describe in detail experimental aspects to obtain HGW specimens, show the ultrastructure of the deposits using electron microscopy, and discuss the mechanism of our hyperquenching method.

Towards the experimental decomposition rate of carbonic acid (H2CO3) in aqueous solution.

Dry carbonic acid has recently been shown to be kinetically stable even at room temperature. Addition of water molecules reduces this stability significantly, and the decomposition (H2CO3 + nH2O --> (n+1)H2O + CO2) is extremely accelerated for n = 1, 2, 3. By including two water molecules, a reaction rate that is a factor of 3000 below the experimental one (10 s(-1)) at room temperature was found. In order to further remove the gap between experiment and theory, we increased the number of water molecules involved to 3 and took into consideration different mechanisms for thorough elucidation of the reaction. A mechanism whereby the reaction proceedes via a six-membered transition state turns out to be the most efficient one over the whole examined temperature range. The determined reaction rates approach experimental values in aqueous solution reasonably well; most especially, a significant increase in the rates in comparison to the decomposition reaction with fewer water molecules is found. Further agreement with experiment is found in the kinetic isotope effects (KIE) for the deuterated species. For water-free carbonic acid, the KIE (i.e., kH2CO3/kD2CO3) for the decomposition reaction is predicted to be 220 at 300 K, whereas it amounts to 2.2-3.0 for the investigated mechanisms including three water molecules. This result is therefore reasonably close to the experimental value of 2 (at 300 K). These KIEs are in much better accordance with the experiment than the KIE for decomposition with fewer water entities.