157 research outputs found

    Comparison of personality traits among patients with psoriasis, atopic dermatitis, and stress: a pilot study

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    Background: Psoriasis and atopic dermatitis are chronic skin diseases that greatly affect the quality of life. Both diseases can be triggered or exacerbated by stress. Objective: We aimed to differentiate personality traits between patients with chronic skin conditions and people treated for stress in a pilot study. Methods: Patients participating voluntarily in educational programs in Belgium and Switzerland were recruited to complete personality trait questionnaires, including the Temperament and Character Inventory (TCI) and the Tridimensional Personality Questionnaire (TPQ). A comparison was made with patients treated for work-related stress. Results: A total of 48 and 91 patients suffering from skin diseases and work-related stress, respectively, were included in the study. Based on the questionnaires, we found that dermatology patients were less persistent and impulsive than those with work-related stress. Dermatology patients also exhibited more rigidness and less focus on performance. Finally, patients with work-related stress seem more likely to change in response to health-promoting programs than patients with chronic dermatoses. Conclusion: Patients with chronic skin diseases may perceive and cope with stress differently in comparison to patients with work-related stress due to inherent personality traits. Therefore, stress coping mechanisms may differ among different diseases. More research is needed into the design of educational interventions and the impact of personality traits in disease-specific groups

    Enamel Structure in Primates: A Review of Scanning Electron Microscope Studies

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    Comparative studies of dental enamel microstructure have involved three main areas of enquiry, with structural features having been investigated in relation to developmental mechanisms, function and/or phylogeny. The phylogenetic, or taxonomic aspect has been emphasized in the majority of studies involving the Order Primates, where efforts have focused upon attempts to recognise structural differences among various hierarchical groups. Studies of primate enamel microstructure by SEM are reviewed here, with emphasis on what has been learned concerning the most suitable preparative techniques that can be employed, and with particular emphasis to the relevance of enamel microstructure in taxonomic analyses of living and fossil primates. No one technique of enamel preparation can be held to be the most suitable for all types of material (e.g., fresh developing, wet mature, dry mature, and fossil enamel) but experience to date allows us to make some recommendations. Two aspects of enamel structure have been shown to possess considerable potential in taxonomic analyses: the enamel prism packing patterns, and the enamel formation rates as documented from prism cross-striation repeat intervals. Although the distribution of enamel prism packing patterns among primates suggests considerable homoplasy of this character, this feature does have considerable taxonomic interest at certain hierarchical levels in Primates. The study of rates of enamel secretion coupled with analyses of enamel thickness has considerable potential in resolving taxonomic and phylogenetic questions

    Reptile enamel matrix proteins: Selection, divergence, and functional constraint

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    The three major enamel matrix proteins (EMPs): amelogenin (AMEL), ameloblastin (AMBN), and enamelin (ENAM), are intrinsically linked to tooth development in tetrapods. However, reptiles and mammals exhibit significant differences in dental patterning and development, potentially affecting how EMPs evolve in each group. In most reptiles, teeth are replaced continuously throughout life, while mammals have reduced replacement to only one or two generations. Reptiles also form structurally simple, aprismatic enamel while mammalian enamel is composed of highly organized hydroxyapatite prisms. These differences, combined with reported low sequence homology in reptiles, led us to predict that reptiles may experience lower selection pressure on their EMPs as compared with mammals. However, we found that like mammals, reptile EMPs are under moderate purifying selection, with some differences evident between AMEL, AMBN, and ENAM. We also demonstrate that sequence homology in reptile EMPs is closely associated with divergence times, with more recently diverged lineages exhibiting high homology, along with strong phylogenetic signal. Lastly, despite sequence divergence, none of the reptile species in our study exhibited mutations consistent with diseases that cause degeneration of enamel (e.g. amelogenesis imperfecta). Despite short tooth retention time and simplicity in enamel structure, reptile EMPs still exhibit purifying selection required to form durable enamel.We calculated the percent identity between amino acid sequences of ameloblastin from various reptile groups. Crocodilians exhibit the highest sequence identity, while identity across squamates was substantially lower. Upon closer examination of the individual squamate clades, however, we found that identity values are actually much higher in snakes, with much of the variation existing between the various lizard infraorders.HIGHLIGHTSReptile enamel matrix proteins are under moderate purifying selection despite polyphyodonty and simple enamel structure.Sequence identity in reptile enamel matrix proteins exhibit correlation with divergence times in spite of differences in substitution rates.Reptile amelogenin operates under a distinct selection regime compared with ameloblastin and enamelin.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/1/jezb22857.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/2/jezb22857-sup-0001-Supplementary_file.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/3/jezb22857-sup-0007-Supplementary_file_S8-DAMBE-Saturation.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/4/jezb22857-sup-0002-Supplementary_file_S1-SpeciesTable.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/5/jezb22857-sup-0003-Supplementary_file_S2_Alignments.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/6/jezb22857-sup-0008-Supplementary_File_S9.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/7/jezb22857-sup-0005-Supplementary_file_S6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/8/jezb22857_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/9/jezb22857-sup-0009-Supplementary_file_Reptiles.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150577/10/jezb22857-sup-0006-Supplementary_file_S7-DIVERGE.pd

    Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei

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    The Plio-Pleistocene hominin Paranthropus boisei had enormous, flat, thickly enameled cheek teeth, a robust cranium and mandible, and inferred massive, powerful chewing muscles. This specialized morphology, which earned P. boisei the nickname “Nutcracker Man”, suggests that this hominin could have consumed very mechanically challenging foods. It has been recently argued, however, that specialized hominin morphology may indicate adaptations for the consumption of occasional fallback foods rather than preferred resources. Dental microwear offers a potential means by which to test this hypothesis in that it reflects actual use rather than genetic adaptation. High microwear surface texture complexity and anisotropy in extant primates can be associated with the consumption of exceptionally hard and tough foods respectively. Here we present the first quantitative analysis of dental microwear for P. boisei. Seven specimens examined preserved unobscured antemortem molar microwear. These all show relatively low complexity and anisotropy values. This suggests that none of the individuals consumed especially hard or tough foods in the days before they died. The apparent discrepancy between microwear and functional anatomy is consistent with the idea that P. boisei presents a hominin example of Liem's Paradox, wherein a highly derived morphology need not reflect a specialized diet

    Frontal sinuses and human evolution

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    The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species? holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species. Variation in frontal sinus shape and dimensions has high potential for phylogenetic discussion when studying human evolution
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