Time Trends in Adolescent School Absences and Associated Bullying Involvement Between 2000 and 2019: A Nationwide Study.

Education is a central determinant of adolescent health. School absences and bullying involvement jeopardize wellbeing, mental health, and educational attainment. We analyzed time trends in school absenteeism over two decades and examined the association of absenteeism with bullying involvement.We analyzed data from the nationwide School Health Promotion study, with self-reported data from Finnish middle school students in grades 8 and 9 (ages 14-17, N = 1 000 970). Questionnaires assessed frequency of illness absences (IA), truancy, frequency of bullying victimization, bullying perpetration, and involvement in both bullying perpetration and victimization. Frequent school absences were defined as occurring on more than 3 days during the prior month (2000-2015), or at least weekly (2017-2019).Frequent IA increased from 12% to 2000 to 22% in 2015. In 2017-2019, frequent IA was reported by 3.5%. Frequent truancy declined from 9% to 2000 to 4% in 2015, and remained at 4% during 2017-2019. Bully victimization was reported at least weekly by 6.9%, perpetration by 5.4% and victimization-perpetration by 1.9% of participants in total. In a logistic regression model, every type of bullying involvement increased odds for both IA and truancy.Since bullying involvement was associated with both IA and truancy, particular concern should be raised for adolescents involved in bullying, and for their social and educational functioning. The concurrent increase in IA and decrease in truancy may reflect destigmatization of mental health problems or other changes in reporting absenteeism.

Tactile friction of topical creams and emulsions: Friction measurements on excised skin and VitroSkin® using ForceBoard™.

Tactile perception can be investigated through ex vivo friction measurements using a so-called ForceBoard™, providing objective assessments and savings in time and money, compared to a subjective human panel. In this work we aim to compare excised skin versus VitroSkin® as model substrates for tactile friction measurements. A further aim is to detect possible differences between traditional surfactant-based creams, and a particle-stabilized (Pickering) cream and investigate how the different substrates affect the results obtained. It was found that the difference in tactile friction between excised skin and VitroSkin® was small on untreated substrates. When topical creams were applied, the same trends were observed for both substrates, although the frictional variation over time relates to the difference in surface structure between the two substrates. The results also confirmed that there is a difference between starch-based Pickering formulations and surfactant-based creams after application, indicating that the latter is greasier than Pickering cream. It was also shown that the tactile friction of Pickering emulsions was consistently high even with high amounts of oil, indicating a non-greasy, and non-sticky formulation. The characteristics of starch-stabilized Pickering formulations make them promising candidates in the development of surfactant-free topical formulations with unique tactile properties.

Relationship between sensorial and physical characteristics of topical creams: A comparative study on effects of excipients.

Rising consumer demands for safer, more natural, and sustainable topical products have led to increased interest in finding alternative excipients, while retaining functionality and cosmetic appeal. Particle-stabilized Pickering creams have emerged as possible alternatives to replace traditional surfactant-stabilized creams and are thus one of the focuses in this study. The aim of this paper was to study relationships between sensorial characteristics and physical properties to understand how different excipients affect these aspects, comparing one starch particle-stabilized and three surfactant-stabilized formulations. A human panel was used to evaluate sensorial perception, while physical properties were deduced by rheology and tactile friction, together with in vivo and ex vivo skin hydration measurements. The results show that sensorial attributes related to the application phase can be predicted with rheology, while afterfeel attributes can be predicted with tactile friction studies. Differences in rheological and sensory properties among surfactant-based creams could mainly be attributed to the type of emollients used, presence of thickeners and surfactant composition. Differences between surfactant-based creams and a Pickering cream were more evident in relation to the afterfeel perception. Presence of starch particles in the residual film on skin results in high tactile friction and low perception of residual coating, stickiness, greasiness, and slipperiness in sensorial afterfeel.

The role of self-rated health in the association between chronic somatic diseases and climacteric-related symptoms.

OBJECTIVES: We have previously shown an association between several chronic somatic diseases and climacteric-related symptoms. This time, we investigated whether self-rated health (SRH) contributes to this association. METHODS: The Women's Health Questionnaire was used to evaluate the climacteric-related symptoms, and existence of the diseases was investigated in 3421 women (41-54 years). In our previous study, the associations were defined with multivariable analyses. In the present study, SRH (good, moderate or bad) was included as a covariate. RESULTS: Most of the previously found associations between the diseases and the symptoms lost their significance. Accordingly, SRH played an important role in the association between the diseases and the symptoms related to the climacteric. CONCLUSIONS: SRH seems to be of significant importance regarding the relationship between the chronic somatic diseases and the symptoms related to climacteric. Most of the diseases are not associated with the climacteric-related symptoms if the disease does not deteriorate the SRH. Thus, women's own perception of their health is crucial for their symptomatology.

Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics - a double-blind, randomized and controlled study.

OBJECTIVES: The mammalian skin is a barrier that effectively separates the water-rich interior of the body from the normally dryer exterior. Changes in the external conditions, for example ambient humidity, have been shown to affect the skin barrier properties. The prime objective of this study was to evaluate the effect of water activity of a topical formulation on skin hydration and permeability. A second objective was to gain more understanding on how two commonly used humectants, urea and glycerol, affect skin barrier function in vivo. METHODS: Simple aqueous formulations were applied under occlusion to the volar forearm of healthy volunteers. Following 4-h exposure, skin water loss (by transepidermal water loss measurements), skin hydration (by Corneometry) and skin permeability (by time to vasodilation due to benzyl nicotinate exposure) were monitored. RESULTS: The results demonstrate that a relatively small change in the water activity of a topical formulation is sufficient to induce considerable effects on stratum corneum hydration and permeability to exogenous substances. Exposing the skin to high water activity leads to increased skin hydration and also increased permeability. Furthermore, urea and glycerol promote skin hydration and permeability even at reduced water activity of the applied formulation. CONCLUSION: These results highlight the importance of considering the water activity in topically applied formulations and the potential benefit of using humectants. The results may impact formulation optimization in how to facilitate skin hydration and to modify skin permeability by temporarily open and close the skin barrier.

Effects of water gradients and use of urea on skin ultrastructure evaluated by confocal Raman microspectroscopy.

The rather thin outermost layer of the mammalian skin, stratum corneum (SC), is a complex biomembrane which separates the water rich inside of the body from the dry outside. The skin surface can be exposed to rather extreme variations in ambient conditions (e.g. water activity, temperature and pH), with potential effects on the barrier function. Increased understanding of how the barrier is affected by such changes is highly relevant for regulation of transdermal uptake of exogenous chemicals. In the present study we investigate the effect of hydration and the use of a well-known humectant, urea, on skin barrier ultrastructure by means of confocal Raman microspectroscopy. We also perform dynamic vapor sorption (DVS) microbalance measurements to examine the water uptake capacity of SC pretreated with urea. Based on novel Raman images, constructed from 2D spectral maps, we can distinguish large water inclusions within the skin membrane exceeding the size of fully hydrated corneocytes. We show that these inclusions contain water with spectral properties similar to that of bulk water. The results furthermore show that the ambient water activity has an important impact on the formation of these water inclusions as well as on the hydration profile across the membrane. Urea significantly increases the water uptake when present in skin, as compared to skin without urea, and it promotes formation of larger water inclusions in the tissue. The results confirm that urea can be used as a humectant to increase skin hydration.

The skin barrier from a lipid perspective.

This contribution summarises the results from a number of investigations undertaken in the spirit of the Domain Mosaic Model proposed by Forslind in 1994. Atomic Force Microscopy (AFM) studies on the two-dimensional phase behaviour of some stratum corneum lipids revealed phase separation of the lipids in the typical case and the ability of cholesterol to reduce the line tension between phases. A theoretical model was developed describing the response of an oriented stack of polar lipid bilayers in the presence of a gradient in water chemical potential (water solution to humid air). The gradient gives rise to an inhomogeneous water swelling, and presumably to a liquid crystal-to-gel transition in the lamellar region closest to humid air. Skin penetration enhancers such as Azone and oleic acid cause phase transformations in lipid bilayer systems which may be relevant in the context of skin permeation.

Structure-related aspects on water diffusivity in fatty acid-soap and skin lipid model systems.

Simplified skin barrier models are necessary to get a first hand understanding of the very complex morphology and physical properties of the human skin barrier. In addition, it is of great importance to construct relevant models that will allow for rational testing of barrier perturbing/occlusive effects of a large variety of substances. The primary objective of this work was to study the effect of lipid morphology on water permeation through various lipid mixtures (i.e., partly neutralised free fatty acids, as well as a skin lipid model mixture). In addition, the effects of incorporating Azone((R)) (1-dodecyl-azacycloheptan-2-one) into the skin lipid model mixture was studied. Small- and wide-angle X-ray diffraction was used for structure determinations. It is concluded that: (a) the water flux through a crystalline fatty acid-sodium soap-water mixture (s) is statistically significantly higher than the water flux through the corresponding lamellar (L(alpha)) and reversed hexagonal (H(II)) liquid crystalline phases, which do not differ between themselves; (b) the water flux through mixtures of L(alpha)/s decreases statistically significantly with increasing relative amounts of lamellar (L(alpha)) liquid crystalline phase; (c) the addition of Azone((R)) to a skin lipid model system induces a reduction in water flux. However, further studies are needed to more closely characterise the structural basis for the occlusive effects of Azone((R)) on water flux.

A new computer-based evaporimeter system for rapid and precise measurements of water diffusion through stratum corneum in vitro.

It is important to have reliable methods for evaluation of skin barrier function when questions such as barrier perturbing effects of different agents and occlusive effects of different formulations are to be elucidated. A wealth of clinical work relates to measurements of transepidermal water loss in vivo, a method much affected by ambient air relative humidity, temperature, skin irritation processes, psychologic status of the subject, etc., factors that cause the method to suffer from low precision (i.e., high random error). Relating to these obstacles, we have developed a closed in vitro system for measurements of water diffusion rate through pieces of isolated stratum corneum at steady-state conditions, where the relative humidity and temperature is held constant and data can be collected continuously. Our evaporimeter-based in vitro system has a more than 3-fold higher precision (lower random error) ( approximately 10%) than measurements of transepidermal water loss in vivo ( approximately 35%). The results of our study show that: (i) the corneocyte envelopes contribute to the barrier capacity of stratum corneum; (ii) removal of the lipid intercellular matrix results in approximately a 3-fold increase in the water diffusion rate through the isolated stratum corneum (n = 20; p < 0.05), not a 100-fold as has previously been suggested; (iii) exposure to sodium dodecyl sulfate in water does neither alter the water diffusion rate (n = 10; p > 0.05) nor the water holding capacity (n = 10; p > 0.05) of stratum corneum; (iv) exposure to 1 M CaCl2 in water yields an increased water diffusion rate through stratum corneum (n = 10; p < 0.05); and (v) when applied to the stratum corneum in excess concentrations, the penetration enhancer Azone has occlusive effects on water diffusion through the stratum corneum (n = 6; p < 0.05).

Phase coexistence in cholesterol-fatty acid mixtures and the effect of the penetration enhancer Azone.

Small and wide-angle X-ray diffraction was used to study the phase behaviour of cholesterol-fatty acid mixtures in an attempt to understand lipid interaction occurring in the stratum corneum, the outermost layer of skin. The effect of the penetration enhancer Azone was investigated as well. It was found that equimolar mixtures of cholesterol, palmitic acid and oleic acid (with the acids neutralised to 41 mol%) in 25% (wt/wt) water typically showed three phases at room temperature, two crystalline and one gel phase. The crystalline phases consisted mainly of palmitic acid:soap and cholesterol, respectively. The water present was unevenly distributed and was associated with the gel phase. Both cholesterol and palmitic acid seemed to be depleted from their crystalline phases by Azone. The electrostatic effects on titration of fatty acids in lamellar aggregates were calculated in view of the present results, and the effects of phase separation were discussed.

A novel approach to the understanding of human skin barrier function.

The basis for externally caused skin disorders is penetration of the skin barrier. A recent model for the skin barrier, the domain mosaic model, based on current knowledge of the physics of lipid bilayer organization gave tentative explanations for several aspects of function. It is demonstrated here that a development of the model explains how the requirements are met for a water-tight structure that will still allow a controlled, minute loss of water, the perspiratio insensibilis, necessary for maintaining plasticity of the keratin. A major advantage of the extended model is that it allows an interpretation of the changes imposed on the structure when in contact with detergents and/or penetration enhancers.

Bicontinuous cubic phase: a model for investigating the effects on a lipid bilayer due to a foreign substance.

Biological effects of foreign substances are usually caused by their interaction within lipid bilayers with the membrane lipids. It is therefore desirable in many situations to determine the effects and the partition of xenobiotic substances, as well as drugs, added to amphiphile-water systems. Bicontinuous cubic liquid crystals provide three-dimensional isotropic matrices with symmetries easily obtained by X-ray diffraction, and were shown to be a useful tool for an initial investigation of the molecular properties possessed by a foreign substance. The concept is illustrated by adding the transdermal penetration enhancer Azone (n-dodecyl-caprolactam) to V2-phases in the glycerol monooleate (GMO)-water system. The weakly polar, water immiscible, Azone is known to favour reversed types of phases in liquid crystals. In the present investigation, Azone was shown to prefer the lipid bilayer interior, with about 19% anchored in the lipid-water interfacial region. Some dependence of its location on water concentration was indicated. The unexpected swelling behaviour of monoacylglycerols in water (L2-->L alpha-->V2) were postulated to result from the lipids changing their polar headgroup conformation, thus allowing for an increase in packing parameter upon increasing the water content.

Effects of pre- and postnatal haloperidol administrations to pregnant and nursing rats on brain catecholamine levels in their offspring.

Effects of perinatal, maternal treatments with haloperidol on brain catecholamine and serotonin concentrations in maturing offspring were examined. The drug was administered orally, at three different dosages, each day from the 14th gestational day to postnatal day 12. At 14, 22, 53 and 90 days of age offspring were selected for regional assays of amine neurotransmitter concentrations. The results indicate that haloperidol can alter the developmental accumulation of central catecholaminergic neurotransmitters. The drug-induced decreases in cortical and spinal norepinephrine levels and in striatal dopamine content in the offspring persisted into adulthood. Regional serotonin concentrations in offspring were not affected by the maternal haloperidol treatments. These findings suggest that central catecholamine receptors are necessary for normal development of dopaminergic and noradrenergic innervation in the central nervous system.

High density lipoprotein metabolism in normolipidemic and cholesterol-fed rabbits.

New Zealand white rabbits were used to determine the compositional and metabolic changes induced in high density lipoproteins (HDL, rho = 1.063--1.21 g/ml) in response to cholesterol feeding. There was no change in total HDL cholesterol in plasma due to cholesterol feeding (12 weeks), but the triglyceride level was decreased to 29% of pretreatment values. Total protein content of HDL was decreased in response to cholesterol feeding, resulting in a significant increase in the cholesterol/protein ratio. There was a decrease in some isomer of the major apolipoproteins (A-I2) of HDL. The decay of radioactivity in HDL or its apolipoproteins was biphasic in both normolipidemic and hypercholesterolemic rabbits. The first phase was much more rapid than the second. The decay rates for the radioactivity in HDL depended upon the dietary status of the recipient animal.