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- Escamilla-García, E, et al.
(författare)
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Antimicrobial Activity of a Cationic Guanidine Compound against Two Pathogenic Oral Bacteria
- 2017
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Ingår i: International journal of microbiology. - : Hindawi Limited. - 1687-918X .- 1687-9198. ; 2017, s. 5924717-
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluated the potential antimicrobial properties of a polyguanidine (CatDex) on two oral bacteria. Chlorhexidine gluconate 1340 μmoL L−1(CHX 0.12%) was used as control.Streptococcus mutans (S. mutans)andPorphyromonas gingivalis (P. gingivalis)were grown in BHI media. Bacterial sensitivity and antimicrobial activity were determined by the minimum inhibitory concentration (MIC) and Kirby-Bauer methods. To study side effects, that is, toxicity, dental pulp stem cells (DPSCs) were used. Fluorometric cytotoxicity and confocal microscopy assays were used in order to test cell viability. CatDex inhibited growth ofS. mutansat all concentrations and growth ofP. gingivalisat all concentrations except 25 μmoL L−1. The MIC of CatDex was 50 μmoL L−1for bothS. mutansandP. gingivalis. The inhibition of bacteria exposed for 8 h at 50 μmoL L−1of CatDex exhibited increased antimicrobial activity over time, with 91% inhibition in both bacteria. The antimicrobial activities of CatDex and CHX were similar when tested on two common bacteria. CatDex was significantly less toxic to DPSCs. CatDex toxicity depended on time and not on concentration. With regard to clinical relevance, CatDex may have potential as a novel antimicrobial agent. Further studies are in progress.
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- De La Garza, Randolph Glenn, et al.
(författare)
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A fossil sea turtle (Reptilia, Pan-Cheloniidae) with preserved soft tissues from the Eocene Fur Formation of Denmark
- 2021
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Ingår i: Journal of Vertebrate Paleontology. - : Informa UK Limited. - 0272-4634 .- 1937-2809. ; 41:3
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Tidskriftsartikel (refereegranskat)abstract
- A new hard-shelled sea turtle (Pan-Cheloniidae) with vestigial soft tissues from the lower Eocene (Ypresian) Fur Formation of Denmark is described and illustrated. The fossil (DK 807) comprises a partial, yet fully articulated carapace (estimated original length ∼50 cm) where the individual bones mostly are preserved in three dimensions, together with an intact sacrum, a consecutive series of articulated caudal vertebrae, a complete pelvic girdle, and both hind limbs. Primitive characters in the pelvis and limbs, along with free ribs that contact the posterior peripherals suggest affinity with the extinct pan-cheloniid Eochelone; however, because of the incomplete nature of the fossil, DK 807 is kept in open nomenclature. Associated with the skeletal elements are soft-tissue residues that include remnant epidermal scutes and a nearly complete outline of a rear paddle. The flipper-shaped halo likely represents traces of skin preserved as a dark bedding-parallel film. Its wrinkled and striated surface texture attests to an originally scaleless configuration comparable to the soft integument of living adult dermochelyid (leatherback) turtles, and unlike that of extant cheloniids. Scratches, scars and indentations on the bony carapace likely represent incompletely healed bite marks inflicted by a crocodylian or another large-sized seagoing tetrapod.
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- De La Garza, Randolph Glenn, et al.
(författare)
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An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes
- 2022
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Ingår i: Scientific Reports. - : Nature Research. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid—unlike its scaly living descendants—combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle. © 2022, The Author(s).
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- De La Garza, Randolph G., et al.
(författare)
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Preservational modes of some ichthyosaur soft tissues (Reptilia, Ichthyopterygia) from the Jurassic Posidonia Shale of Germany
- 2023
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Ingår i: Palaeontology. - : John Wiley and Sons Inc. - 0031-0239 .- 1475-4983. ; 66:4
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Tidskriftsartikel (refereegranskat)abstract
- Konservat-Lagerstätten, such as the Toarcian (Early Jurassic) Posidonia Shale of southwestern Germany, are renowned for their spectacular fossils. Ichthyosaur skeletons recovered from this formation are frequently associated with soft tissues; however, the preserved material ranges from three-dimensional, predominantly phosphatized structures to dark films of mainly organic matter. We examined soft-tissue residues obtained from two ichthyosaur specimens using an integrated ultrastructural and geochemical approach. Our analyses revealed that the superficially-looking ‘films’ in fact comprise sections of densely aggregated melanosome (pigment) organelles sandwiched between phosphatized layers containing fibrous microstructures. We interpret this distinct layering as representing condensed and incompletely degraded integument from both sides of the animal. When compared against previously documented ichthyosaur fossils, it becomes readily apparent that a range of preservational modes exists between presumed ‘phosphatic’ and ‘carbonized’ soft-tissue remains. Some specimens show high structural fidelity (e.g. distinct integumentary layering), while others, including the fossils examined in this study, retain few original anatomical details. This diversity of soft-tissue preservational modes among Posidonia Shale ichthyosaurs offers a unique opportunity to examine different biostratinomic, taphonomic and diagenetic variables that potentially could affect the process of fossilization. It is likely that soft-tissue preservation in the Posidonia Shale was regulated by a multitude of factors, including decay efficiency and speed of phosphatic mineral nucleation; these in turn were governed by a seafloor with sustained microbial mat activity fuelled by high organic matter input and seasonally fluctuating oxygen levels. © 2023 The Authors.
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- De La Garza, Randolph
(författare)
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Preservation of Marine Reptile Soft Parts: Reconstructing the Life and Death of Ancient Leviathans
- 2022. - Litholund theses
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Marine reptiles constitute a diverse group of secondarily aquatic tetrapods that have inhabited the world’s oceans for the greater part of the last 250 million years. While certain large-scale anatomical changes have been observed through progressive alterations of their skeletal morphology (e.g., the evolution of fin-like limbs), little is known about those changes that have occurred in the integument during their transition from landlubbers to leviathans.This thesis has three main objectives: (1) to obtain novel ultrastructural and chemical information from fossilized marine reptile skin using a combination of cutting-edge analytical tools (e.g., mass spectrometry and spectroscopy); (2) to infer aspects of evolution, paleobiology and paleoecology from the acquired data; and (3) to deduce how skin is retained in the fossil record. To accomplish these aims, four exceptionally preserved soft-tissue fossils representing two major marine reptile clades were used as exemplary animals: a sea turtle from the earliest Eocene (~54 Ma) Fur Formation of Denmark and three ichthyosaurs from the Early Jurassic (~183 Ma) Posidonia Shale of Germany.The fossil sea turtle comprises a partial but semi-articulated skeleton with adhering scutes and dark-colored organic matter that surrounds one of the hind limbs. Comparisons with previously reported Eocene turtles identify the Fur Formation specimen as a stem pan-cheloniid, and more specifically as a close relative of Eochelone. Furthermore, the fossil preserves a mosaic of integumental features not previously documented in any living or extinct turtle: a shell covered in scutes and limbs devoid of scales. Collectively, my findings suggest that the adaptive transition to neritic waters by the ancestral panchelonioids was more complex than hitherto appreciated.Ichthyosaur skeletons with associated body outlines, have been the focus of scientific studies for almost 200 years. The recent discovery of relict blubber and countershading in an exceptionally preserved Stenopterygius indicates that derived ichthyosaurs were warm-blooded and thus even more dolphin-like than previously thought. This new knowledge has been used to create the most scientifically accurate sculptural model of an ichthyosaur to date, and the process on how this was achieved is the focus of my third paper.Ichthyosaurs from the Jurassic Posidonia Shale exhibit a range of preservational modes. An isolated dorsal fin and tail fluke were examined and compared against a previously documented semi-complete individual to determine potential qualitative differences in preservation between the three specimens. Microscopic and molecular examination revealed that the fin fossils comprise mats of densely packed melanosomes sandwiched between layers enriched in calcium phosphate. I interpret this structural arrangement as representing incompletely preserved skin from both sides of the fins. When compared against specimens with higher structural fidelity (such as the semi-complete specimen), it is readily apparent that the fins had reached an advance stage of decay before entering the fossil record. I conclude that differences in preservational modes between Posidonia Shale soft-tissue ichthyosaurs largely are a function of when and how fast mineralization could outpace decomposition.
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| 10. |
- Eriksson, Mats E., et al.
(författare)
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A review of ichthyosaur (Reptilia, Ichthyopterygia) soft tissues with implications for life reconstructions
- 2022
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252. ; 226
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Forskningsöversikt (refereegranskat)abstract
- The dolphin-like ichthyosaurs – also known as ‘fish lizards’ – are extinct marine reptiles that roamed the Mesozoic oceans for some 160 million years. As for most ancient vertebrates, our knowledge of these iconic animals largely derives from biomineralized hard parts (teeth and bones). However, soft tissues are also known from a number of Lagerstätte specimens, and have opened up new avenues for deciphering their biology and ecology. Herein, we present a review of ichthyosaur research and life style iconography with particular focus on soft-tissue structures and inferences made from these, including aspects of coloration and thermoregulation. We then distill novel insights on ichthyosaur anatomy and physiology gained from an exceptionally preserved, sub-adult specimen of the parvipelvian Stenopterygius from the Jurassic Posidonia Shale in Germany, and describe the process in which a detailed, three-dimensional reconstruction in scale 1:1 was produced. Our new sculpture is based on empirical evidence obtained directly from the fossil record, including uniquely preserved soft-tissue structures (e.g., original pigments and blubber), resulting in the scientifically most up-to-date reconstruction of an ichthyosaur currently available.
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| 12. |
- Heidbuchel, Hein, et al.
(författare)
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Recommendations for participation in leisure-time physical activity and competitive sports of patients with arrhythmias and potentially arrhythmogenic conditions. Part 2: ventricular arrhythmias, channelopathies, and implantable defibrillators.
- 2021
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Ingår i: Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology. - : Oxford University Press (OUP). - 1532-2092. ; 23:1, s. 147-148
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Tidskriftsartikel (refereegranskat)abstract
- This paper belongs to a series of recommendation documents for participation in leisure-time physical activity and competitive sports by the European Association of Preventive Cardiology (EAPC). Together with an accompanying paper on supraventricular arrhythmias, this second text deals specifically with those participants in whom some form of ventricular rhythm disorder is documented, who are diagnosed with an inherited arrhythmogenic condition, and/or who have an implanted pacemaker or cardioverter defibrillator. A companion text on recommendations in athletes with supraventricular arrhythmias is published in the European Journal of Preventive Cardiology. Since both texts focus on arrhythmias, they are the result of a collaboration between EAPC and the European Heart Rhythm Association (EHRA). The documents provide a framework for evaluating eligibility to perform sports, based on three elements, i.e. the prognostic risk of the arrhythmias when performing sports, the symptomatic impact of arrhythmias while performing sports, and the potential progression of underlying structural problems as the result of sports.
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| 13. |
- Levitis, E, et al.
(författare)
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Centering inclusivity in the design of online conferences-An OHBM-Open Science perspective
- 2021
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Ingår i: GigaScience. - : Oxford University Press (OUP). - 2047-217X. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- As the global health crisis unfolded, many academic conferences moved online in 2020. This move has been hailed as a positive step towards inclusivity in its attenuation of economic, physical, and legal barriers and effectively enabled many individuals from groups that have traditionally been underrepresented to join and participate. A number of studies have outlined how moving online made it possible to gather a more global community and has increased opportunities for individuals with various constraints, e.g., caregiving responsibilities.Yet, the mere existence of online conferences is no guarantee that everyone can attend and participate meaningfully. In fact, many elements of an online conference are still significant barriers to truly diverse participation: the tools used can be inaccessible for some individuals; the scheduling choices can favour some geographical locations; the set-up of the conference can provide more visibility to well-established researchers and reduce opportunities for early-career researchers. While acknowledging the benefits of an online setting, especially for individuals who have traditionally been underrepresented or excluded, we recognize that fostering social justice requires inclusivity to actively be centered in every aspect of online conference design.Here, we draw from the literature and from our own experiences to identify practices that purposefully encourage a diverse community to attend, participate in, and lead online conferences. Reflecting on how to design more inclusive online events is especially important as multiple scientific organizations have announced that they will continue offering an online version of their event when in-person conferences can resume.
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| 14. |
- Liddell, P. A., et al.
(författare)
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Photonic switching of photoinduced electron transfer in a dihydropyrene-porphyrin-fullerene molecular triad
- 2004
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Ingår i: Journal of the American Chemical Society. ; 126:15, s. 4803-4811
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Tidskriftsartikel (refereegranskat)abstract
- Photonic control of photoinduced electron transfer has been demonstrated in a dimethyldihydropyrene (DHP) porphyrin (P) fullerene (C-60) molecular triad. In the DHP-P-C-60 form of the triad, excitation of the porphyrin moiety is followed by photoinduced electron transfer to give a DHP-P.+-C-60(.-) charge-separated state, which evolves by a charge shift reaction to DHP.+-P-C-60(.-). This final state has a lifetime of 2 mus and is formed in an overall yield of 94%. Visible (greater than or equal to300 nm) irradiation of the triad leads to photoisomerization of the DHP moiety to the cyclophanediene (CPD). Excitation of the porphyrin moiety of CPD-P-C-60 produces a short-lived (
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