Freeze dehydration vs. supercooling of mesophyll cells: Impact of cell wall, cellular and tissue traits on the extent of water displacement.

The extent of freeze dehydration of mesophyll cells in response to extracellular ice varies from supercooling to severe freezing cytorrhysis. The structural factors involved are poorly understood. In a comparison of mesophyll cells of 11 species, the factors "cell wall", "cellular" and "tissue" traits were investigated. The extent of freeze dehydration was quantified as reduction in the sectional area during controlled freezing in the presence of ice. The cell wall thickness, cell size, cell area and the relative area of intercellular spaces were determined. The modulus of elasticity was determined by psychrometry. To grasp the relationships between factors and with freeze dehydration, we applied a principal component analysis. The first two components explain 84% of the variance in the dataset. The first principal component correlated negatively with the extent of freeze dehydration and relative area of intercellular spaces, and positively with the squared cell wall thickness to cell size ratio, elasticity and cell wall thickness. The cell size parameters determined the second principal component. Supercooling appeared preferable in cells with a high squared cell wall thickness to cell size ratio and a low relative area of intercellular spaces. Such factors are hypothesised to affect the magnitude of negative turgor pressure being built up below the turgor loss point. Negative turgor pressure slows dehydration by reducing the water potential gradient to the extracellular ice. With high levels of freeze dehydration, sufficient intercellular spaces for extracellular ice accommodation are needed. The low relative area of intercellular spaces increases cell-to-cell contact area and could support tissue stability.

Reduced ability to discriminate colours - an under-recognised feature of depressive disorders? A pilot study.

Background: Although in clinical practice an impairment of sensory perception is frequently reported by depressed patients no mention of these symptoms is made in DSM-5, ICD-10 or ICD-11. Previous studies on colour perception have largely relied on patient self-reports and few have studied colour discrimination.Methods: The ability to discriminate small colour differences was assessed in 30 patients currently experiencing a moderate to severe depressive episode (ICD-10: F32.1-2, F33.1-2 or F31.3-4) and 32 healthy controls using the colour buttons of the Farnsworth Munsell 100-Hue test. Data were analysed by standard tests for comparing two groups (t-test, Mann-Whitney U-test, Chi-square test) and by ordinal regression and generalised estimating equation models.Results: Depressed patients failed significantly earlier (i.e., at larger differences between adjacent buttons) to discriminate between colours. This finding was retained after adjustment for potential confounders. There was no significant association with age, gender or depression score.Conclusions: We found a reduction in the ability to discriminate colours in depressed patients. This finding underlines the importance of sensory deficits as part of the symptomatology of depression. Sensory impairments should be taken into account in clinical care of patients with depression and should be included in diagnostic manuals. Further studies in larger samples including intra-individual comparisons between the depressed and the remitted state of patients are needed.Key pointsIn clinical practice, an impairment of sensory perception is frequently reported by depressed patients.However, no mention of these symptoms is made in the commonly used diagnostic manuals.In this pilot study, depressed patients and controls differed significantly in terms of the ability to discriminate colours with patients performing worse than their healthy counterparts.Sensory impairments should be taken into account in clinical care of patients with depression and should be included in diagnostic manuals.

Teleology first: Goals before knowledge and belief.

Comparing knowledge with belief can go wrong in two dimensions: If the authors employ a wider notion of knowledge, then they do not compare like with like because they assume a narrow notion of belief. If they employ only a narrow notion of knowledge, then their claim is not supported by the evidence. Finally, we sketch a superior teleological view.

"I Can't Get No Satisfaction"-Psychosocial Aspects and Awareness of Negative Impacts in Chemsex Users: Results from an Anonymous Online Survey.

Chemsex is the interplay of substance use by men who have sex with men (MSM) in sexual contexts. The minority stress model and the identity process theory are explanatory models. In this study, we investigated whether (i) differences in certain psychosocial aspects (i.e., shame, aspects of queer identity, and sexual self-concepts) exist between chemsex users and non-users, and (ii) which factors influence an awareness of negative impacts in chemsex users. We conducted an anonymous, cross-sectional, online survey, including sociodemography, sexual history, history of substance use, validated scales for shame-proneness, aspects of queer identity, and sexual self-concepts. Our analysis comprised descriptive statistics, t-tests, Spearman's correlations, and a multiple linear regression model. We recorded a total of 3257 datasets with 107 chemsex users. Chemsex users showed higher rates for risky sexual behavior. Values for shame proneness, more negative aspects of queer identity, and sexual self-concepts were elevated in chemsex users with an awareness of negative impacts. Sexual anxiety, intravenous substance use, and having had a difficult process coming out were significant predictors of feeling negative impacts. Aspects of shame, queer identity aspects, and sexual self-concepts play an important role in the field of chemsex. Different explanatory models seem to be relevant for different subgroups of chemsex users. Chemsex users with an awareness of a problem were particularly vulnerable and distressed but had the highest motivation for change. Prevention, counseling, and care might profit from the inclusion of these aspects. Further anti-stigma campaigns and a specialization of the healthcare system are needed. Registration: DRKS00022336, date: 29th of October, 2020.