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1.
Clin Oral Investig ; 27(6): 3199-3209, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36864278

RESUMO

OBJECTIVES: Synthetic bone substitutes which can be adapted preoperatively and patient specific may be helpful in various bony defects in the field of oral- and maxillofacial surgery. For this purpose, composite grafts made of self-setting and oil-based calcium phosphate cement (CPC) pastes, which were reinforced with 3D-printed polycaprolactone (PCL) fiber mats were manufactured. MATERIALS AND METHODS: Bone defect models were acquired using patient data from real defect situations of patients from our clinic. Using a mirror imaging technique, templates of the defect situation were fabricated via a commercially available 3D-printing system. The composite grafts were assembled layer by layer, aligned on top of these templates and fitted into the defect situation. Besides, PCL-reinforced CPC samples were evaluated regarding their structural and mechanical properties via X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM), and 3-point-bending testing. RESULTS: The process sequence including data acquisition, template fabrication, and manufacturing of patient specific implants proved to be accurate and uncomplicated. The individual implants consisting mainly of hydroxyapatite and tetracalcium phosphate displayed good processability and a high precision of fit. The mechanical properties of the CPC cements in terms of maximum force and stress load to material fatigue were not negatively affected by the PCL fiber reinforcement, whereas clinical handling properties increased remarkably. CONCLUSION: PCL fiber reinforcement of CPC cements enables the production of very freely modelable three-dimensional implants with adequate chemical and mechanical properties for bone replacement applications. CLINICAL RELEVANCE: The complex bone morphology in the region of the facial skull often poses a great challenge for a sufficient reconstruction of bony defects. A full-fledged bone replacement here often requires the replication of filigree three-dimensional structures partly without support from the surrounding tissue. With regard to this problem, the combination of smooth 3D-printed fiber mats and oil-based CPC pastes represents a promising method for fabricating patient specific degradable implants for the treatment of various craniofacial bone defects.


Assuntos
Implantes Dentários , Humanos , Teste de Materiais , Crânio/cirurgia , Durapatita , Cimentos Dentários , Cimentos de Ionômeros de Vidro , Fosfatos de Cálcio/química , Cimentos Ósseos/química
2.
Phys Rev Lett ; 122(6): 061301, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30822070

RESUMO

We revisit the status of scalar-tensor theories with applications to dark energy in the aftermath of the gravitational wave signal GW170817 and its optical counterpart GRB170817A. At the level of the cosmological background, we identify a class of theories, previously declared unviable in this context, whose anomalous gravitational wave speed is proportional to the scalar equation of motion. As long as the scalar field is assumed not to couple directly to matter, this raises the possibility of compatibility with the gravitational wave data, for any cosmological sources, thanks to the scalar dynamics. This newly "rescued" class of theories includes examples of generalized quintic Galileons from Horndeski theories. Despite the promise of this leading order result, we show that the loophole ultimately fails when we include the effect of large scale inhomogeneities.

3.
J Mol Cell Cardiol ; 120: 31-41, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29777691

RESUMO

The therapeutic potential of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) is limited by immature functional features including low impulse propagation and reduced cell excitability. Key players regulating electrical activity are voltage-gated Na+ channels (Nav1.5) and gap junctions built from connexin-43 (Cx43). Here we tested the hypothesis that enhanced Cx43 expression increases intercellular coupling and influences excitability by modulating Nav1.5. Using transgenic approaches, Cx43 and Nav1.5 localization and cell coupling were studied by confocal imaging. Nav1.5 currents and action potentials (APs) were measured using the patch-clamp technique. Enhanced sarcolemmal Cx43 expression significantly improved intercellular coupling and accelerated dye transfer kinetics. Furthermore, Cx43 modulated Nav1.5 function leading to significantly higher current and enhanced AP upstroke velocities, thereby improving electrical activity as measured by microelectrode arrays. These findings suggest a mechanistic link between cell coupling and excitability controlled by Cx43 expression in iPSC-CMs. Therefore, we propose Cx43 as novel molecular target for improving electrical properties of iPSC-CMs to match the functional properties of native myocytes.


Assuntos
Potenciais de Ação/fisiologia , Conexina 43/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Miócitos Cardíacos/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.5/metabolismo , Animais , Terapia Baseada em Transplante de Células e Tecidos , Células Cultivadas , Estimulação Elétrica , Imunofluorescência , Junções Comunicantes/metabolismo , Genes Reporter/fisiologia , Camundongos , Microscopia Confocal , Técnicas de Patch-Clamp , Plasmídeos , Sarcolema/metabolismo , Transdução Genética , Transfecção
4.
Am Nat ; 191(1): 1-20, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29244561

RESUMO

The large body of theory on speciation with gene flow has brought to light fundamental differences in the effects of two types of mating rules on speciation: preference/trait rules, in which divergence in both (female) preferences and (male) mating traits is necessary for assortment, and matching rules, in which individuals mate with like individuals on the basis of the presence of traits or alleles that they have in common. These rules can emerge from a variety of behavioral or other mechanisms in ways that are not always obvious. We discuss the theoretical properties of both types of rules and explain why speciation is generally thought to be more likely under matching rather than preference/trait rules. We furthermore discuss whether specific assortative mating mechanisms fall under a preference/trait or matching rule, present empirical evidence for these mechanisms, and propose empirical tests that could distinguish between them. The synthesis of the theoretical literature on these assortative mating rules with empirical studies of the mechanisms by which they act can provide important insights into the occurrence of speciation with gene flow. Finally, by providing a clear framework we hope to inspire greater alignment in the ways that both theoreticians and empiricists study mating rules and how these rules affect speciation through maintaining or eroding barriers to gene flow among closely related species or populations.


Assuntos
Fluxo Gênico , Especiação Genética , Preferência de Acasalamento Animal , Fenótipo , Animais , Evolução Biológica , Modelos Genéticos
5.
Bioscience ; 68(10): 805-812, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30364335

RESUMO

According to a recent survey, ecologists and evolutionary biologists feel that theoretical and empirical research should coexist in a tight feedback loop but believe that the two domains actually interact very little. We evaluate this perception using a citation network analysis for two data sets, representing the literature on sexual selection and speciation. Overall, 54%-60% of citations come from a paper's own category, whereas 17%-23% are citations across categories. These cross-citations tend to focus on highly cited papers, and we observe a positive correlation between the numbers of citations a study receives within and across categories. We find evidence that reviews can function as integrators between the two literatures, argue that theoretical models are analogous to specific empirical study systems, and complement our analyses by studying a cocitation network. We conclude that theoretical and empirical research are more tightly connected than generally thought but that avenues exist to further increase this integration.

6.
Phys Rev Lett ; 120(22): 221102, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29906131

RESUMO

Cold dark matter is a crucial constituent of the current concordance cosmological model. Having a vanishing equation of state (EOS), its energy density scales with the inverse cosmic volume and is thus uniquely described by a single number, its present abundance. We test the inverse cosmic volume law for dark matter (DM) by allowing its EOS to vary independently in eight redshift bins in the range z=10^{5} and z=0. We use the latest measurements of the cosmic microwave background radiation from the Planck satellite and supplement them with baryon acoustic oscillation (BAO) data from the 6dF and SDSS-III BOSS surveys and with the Hubble Space Telescope (HST) key project data. We find no evidence for nonzero EOS in any of the eight redshift bins. With Planck data alone, the DM abundance is most strongly constrained around matter-radiation equality ω_{g}^{eq}=0.1193_{-0.0035}^{+0.0036} (95% C.L.), whereas its present-day value is more weakly constrained: ω_{g}^{(0)}=0.16_{-0.10}^{+0.12} (95% C.L.). Adding BAO or HST data does not significantly change the ω_{g}^{eq} constraint, while ω_{g}^{(0)} tightens to 0.160_{-0.065}^{+0.069} (95% C.L.) and 0.124_{-0.067}^{+0.081} (95% C.L.), respectively. Our results constrain for the first time the level of "coldness" required of the DM across various cosmological epochs and show that the DM abundance is strictly positive at all times.

7.
J Math Biol ; 77(5): 1431-1458, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29980824

RESUMO

Continuous environmental change-such as slowly rising temperatures-may create permanent maladaptation of natural populations: Even if a population adapts evolutionarily, its mean phenotype will usually lag behind the phenotype favored in the current environment, and if the resulting phenotypic lag becomes too large, the population risks extinction. We analyze this scenario using a moving-optimum model, in which one or more quantitative traits are under stabilizing selection towards an optimal value that increases at a constant rate. We have recently shown that, in the limit of infinitely small mutations and high mutation rate, the evolution of the phenotypic lag converges to an Ornstein-Uhlenbeck process around a long-term equilibrium value. Both the mean and the variance of this equilibrium lag have simple analytical formulas. Here, we study the properties of this limit and compare it to simulations of an evolving population with finite mutational effects. We find that the "small-jumps limit" provides a reasonable approximation, provided the mean lag is so large that the optimum cannot be reached by a single mutation. This is the case for fast environmental change and/or weak selection. Our analysis also provides insights into population extinction: Even if the mean lag is small enough to allow a positive growth rate, stochastic fluctuations of the lag will eventually cause extinction. We show that the time until this event follows an exponential distribution, whose mean depends strongly on a composite parameter that relates the speed of environmental change to the adaptive potential of the population.


Assuntos
Extinção Biológica , Modelos Biológicos , Adaptação Fisiológica/genética , Animais , Evolução Biológica , Simulação por Computador , Meio Ambiente , Genética Populacional/estatística & dados numéricos , Aquecimento Global , Conceitos Matemáticos , Modelos Genéticos , Mutação , Fenótipo , Característica Quantitativa Herdável , Seleção Genética , Processos Estocásticos
8.
Mol Ecol ; 23(1): 239-50, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24168518

RESUMO

Although classically thought to be rare, female polyandry is widespread and may entail significant fitness benefits. If females store sperm over extended periods of time, the consequences of polyandry will depend on the pattern of sperm storage, and some of the potential benefits of polyandry can only be realized if sperm from different males is mixed. Our study aimed to determine patterns and consequences of polyandry in an amphibian species, the fire salamander, under fully natural conditions. Fire salamanders are ideal study objects, because mating, fertilization and larval deposition are temporally decoupled, females store sperm for several months, and larvae are deposited in the order of fertilization. Based on 18 microsatellite loci, we conducted paternity analysis of 24 female-offspring arrays with, in total, over 600 larvae fertilized under complete natural conditions. More than one-third of females were polyandrous and up to four males were found as sires. Our data clearly show that sperm from multiple males is mixed in the female's spermatheca. Nevertheless, paternity is biased, and the most successful male sires on average 70% of the larvae, suggesting a 'topping off' mechanism with first-male precedence. Female reproductive success increased with the number of sires, most probably because multiple mating ensured high fertilization success. In contrast, offspring number was unaffected by female condition and genetic characteristics, but surprisingly, it increased with the degree of genetic relatedness between females and their sires. Sires of polyandrous females tended to be genetically similar to each other, indicating a role for active female choice.


Assuntos
Reprodução/genética , Salamandra/genética , Comportamento Sexual Animal , Animais , Feminino , Fertilização/fisiologia , Aptidão Genética , Alemanha , Larva/genética , Masculino , Repetições de Microssatélites , Reprodução/fisiologia , Salamandra/fisiologia , Espermatozoides
9.
Adv Healthc Mater ; : e2400426, 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38607966

RESUMO

Melt Electrowriting (MEW) is a continuously growing manufacturing platform. Its advantage is the consistent production of micro- to nanometer fibers, that stack intricately, forming complex geometrical shapes. MEW allows tuning of the mechanical properties of constructs via the geometry of deposited fibers. Due to this, MEW can create complex mechanics only seen in multi-material compounds and serve as guiding structures for cellular alignment. The advantage of MEW is also shown in combination with other biotechnological manufacturing methods to create multilayered constructs that increase mechanical approximation to native tissues, biocompatibility, and cellular response. These features make MEW constructs a perfect candidate for small-diameter vascular graft structures. Recently, studies have presented fascinating results in this regard, but is this truly the direction that tubular MEW will follow or are there also other options on the horizon? This perspective will explore the origins and developments of tubular MEW and present its growing importance in the field of artificial small-diameter vascular grafts with mechanical modulation and improved biomimicry and the impact of it in convergence with other manufacturing methods and how future technologies like AI may influence its progress.

10.
Artigo em Inglês | MEDLINE | ID: mdl-38503505

RESUMO

Speciation can be mediated by a variety of reproductive barriers, and the interaction among different barriers has often been shown to enhance overall reproductive isolation, a process referred to as "coupling." Here, we analyze a population genetics model to study the establishment of linkage disequilibrium (LD) among loci involved in multiple premating barriers, an aspect that has received little theoretical attention to date. We consider a simple genetic framework underlying two distinct premating barriers, each encoded by a preference locus and its associated mating trait locus. We show that their interaction can lead to a decrease in overall reproductive isolation relative to a situation with a single barrier, a process we call "negative coupling." More specifically, in our model, negative coupling results either from sexual selection that reduces divergence at all loci, or from reduced LD that occurs because the presence of many females with "mismatched" preferences causes the mating success of recombinant males to become high. Interestingly, the latter effect may even cause LD among preference loci to become negative when recombination rates among loci are low. We conclude that coincident reproductive barriers may not necessarily reinforce each other, and that the underlying loci may not necessarily develop a positive association.

11.
Adv Sci (Weinh) ; : e2307627, 2024 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-38704690

RESUMO

Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis.

12.
Am Nat ; 182(6): E215-34, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24231546

RESUMO

Adaptive speciation with gene flow via the evolution of assortative mating has classically been studied in one of two different scenarios. First, speciation can occur if frequency-dependent competition in sympatry induces disruptive selection, leading to indirect selection for mating with similar phenotypes. Second, if a subpopulation is locally adapted to a specific environment, then there is indirect selection against hybridizing with maladapted immigrants. While both of these mechanisms have been modeled many times, the literature lacks models that allow direct comparisons between them. Here we incorporate both frequency-dependent competition and local adaptation into a single model and investigate whether and how they interact in driving speciation. We report two main results. First, we show that individually, the two mechanisms operate under separate conditions, hardly influencing each other when one of them alone is sufficient to drive speciation. Second, we also find that the two mechanisms can operate together, leading to a third speciation mode in which speciation is initiated by selection against maladapted migrants but completed by within-deme competition in a distinct second phase. While this third mode bears some similarity to classical reinforcement, it is considerably faster, and both newly formed species go on to coexist in sympatry.


Assuntos
Adaptação Biológica , Especiação Genética , Modelos Biológicos , Animais , Comportamento Competitivo , Fluxo Gênico , Densidade Demográfica , Dinâmica Populacional , Reprodução , Seleção Genética , Comportamento Sexual Animal
13.
IEEE Trans Image Process ; 32: 5737-5750, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37847620

RESUMO

The synthesis of high-resolution remote sensing images based on text descriptions has great potential in many practical application scenarios. Although deep neural networks have achieved great success in many important remote sensing tasks, generating realistic remote sensing images from text descriptions is still very difficult. To address this challenge, we propose a novel text-to-image modern Hopfield network (Txt2Img-MHN). The main idea of Txt2Img-MHN is to conduct hierarchical prototype learning on both text and image embeddings with modern Hopfield layers. Instead of directly learning concrete but highly diverse text-image joint feature representations for different semantics, Txt2Img-MHN aims to learn the most representative prototypes from text-image embeddings, achieving a coarse-to-fine learning strategy. These learned prototypes can then be utilized to represent more complex semantics in the text-to-image generation task. To better evaluate the realism and semantic consistency of the generated images, we further conduct zero-shot classification on real remote sensing data using the classification model trained on synthesized images. Despite its simplicity, we find that the overall accuracy in the zero-shot classification may serve as a good metric to evaluate the ability to generate an image from text. Extensive experiments on the benchmark remote sensing text-image dataset demonstrate that the proposed Txt2Img-MHN can generate more realistic remote sensing images than existing methods. Code and pre-trained models are available online (https://github.com/YonghaoXu/Txt2Img-MHN).

14.
Carbohydr Polym ; 319: 121145, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37567703

RESUMO

Recreating the intricate mechanical and functional gradients found in natural tissues through additive manufacturing poses significant challenges, including the need for precise control over time and space and the availability of versatile biomaterial inks. In this proof-of-concept study, we developed a new biomaterial ink for direct ink writing, allowing the creation of 3D structures with tailorable functional and mechanical gradients. Our ink formulation combined multifunctional cellulose nanofibrils (CNFs), allyl-functionalized gelatin (0.8-2.0 wt%), and polyethylene glycol dithiol (3.0-7.5 wt%). The CNF served as a rheology modifier, whereas a concentration of 1.8 w/v % in the inks was chosen for optimal printability and shape fidelity. In addition, CNFs were functionalized with azido groups, enabling the spatial distribution of functional moieties within a 3D structure. These functional groups were further modified using a spontaneous click chemistry reaction. Through additive manufacturing and a readily available static mixer, we successfully demonstrated the fabrication of mechanical gradients - ranging from 3 to 6 kPa in indentation strength - and functional gradients. Additionally, we introduced dual gradients by combining gradient printing with an anisotropic photocrosslinking step. The developed biomaterial ink opens up possibilities for printing intricate multigradient structures, resembling the complex hierarchical organization seen in living tissues.

15.
Adv Mater ; 35(32): e2300756, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37099802

RESUMO

Major challenges in biofabrication revolve around capturing the complex, hierarchical composition of native tissues. However, individual 3D printing techniques have limited capacity to produce composite biomaterials with multi-scale resolution. Volumetric bioprinting recently emerged as a paradigm-shift in biofabrication. This ultrafast, light-based technique sculpts cell-laden hydrogel bioresins into 3D structures in a layerless fashion, providing enhanced design freedom over conventional bioprinting. However, it yields prints with low mechanical stability, since soft, cell-friendly hydrogels are used. Herein, the possibility to converge volumetric bioprinting with melt electrowriting, which excels at patterning microfibers, is shown for the fabrication of tubular hydrogel-based composites with enhanced mechanical behavior. Despite including non-transparent melt electrowritten scaffolds in the volumetric printing process, high-resolution bioprinted structures are successfully achieved. Tensile, burst, and bending mechanical properties of printed tubes are tuned altering the electrowritten mesh design, resulting in complex, multi-material tubular constructs with customizable, anisotropic geometries that better mimic intricate biological tubular structures. As a proof-of-concept, engineered tubular structures are obtained by building trilayered cell-laden vessels, and features (valves, branches, fenestrations) that can be rapidly printed using this hybrid approach. This multi-technology convergence offers a new toolbox for manufacturing hierarchical and mechanically tunable multi-material living structures.


Assuntos
Bioimpressão , Alicerces Teciduais , Alicerces Teciduais/química , Engenharia Tecidual/métodos , Materiais Biocompatíveis/química , Hidrogéis/química , Impressão Tridimensional , Bioimpressão/métodos
16.
Front Bioeng Biotechnol ; 11: 1285565, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38053846

RESUMO

A previously developed cellularized collagen-based vascular wall model showed promising results in mimicking the biological properties of a native vessel but lacked appropriate mechanical properties. In this work, we aim to improve this collagen-based model by reinforcing it using a tubular polymeric (reinforcement) scaffold. The polymeric reinforcements were fabricated exploiting commercial poly (ε-caprolactone) (PCL), a polymer already used to fabricate other FDA-approved and commercially available devices serving medical applications, through 1) solution electrospinning (SES), 2) 3D printing (3DP) and 3) melt electrowriting (MEW). The non-reinforced cellularized collagen-based model was used as a reference (COL). The effect of the scaffold's architecture on the resulting mechanical and biological properties of the reinforced collagen-based model were evaluated. SEM imaging showed the differences in scaffolds' architecture (fiber alignment, fiber diameter and pore size) at both the micro- and the macrolevel. The polymeric scaffold led to significantly improved mechanical properties for the reinforced collagen-based model (initial elastic moduli of 382.05 ± 132.01 kPa, 100.59 ± 31.15 kPa and 245.78 ± 33.54 kPa, respectively for SES, 3DP and MEW at day 7 of maturation) compared to the non-reinforced collagen-based model (16.63 ± 5.69 kPa). Moreover, on day 7, the developed collagen gels showed stresses (for strains between 20% and 55%) in the range of [5-15] kPa for COL, [80-350] kPa for SES, [20-70] kPa for 3DP and [100-190] kPa for MEW. In addition to the effect on the resulting mechanical properties, the polymeric tubes' architecture influenced cell behavior, in terms of proliferation and attachment, along with collagen gel compaction and extracellular matrix protein expression. The MEW reinforcement resulted in a collagen gel compaction similar to the COL reference, whereas 3DP and SES led to thinner and longer collagen gels. Overall, it can be concluded that 1) the selected processing technique influences the scaffolds' architecture, which in turn influences the resulting mechanical and biological properties, and 2) the incorporation of a polymeric reinforcement leads to mechanical properties closely matching those of native arteries.

17.
Bioessays ; 32(7): 564-70, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20586053

RESUMO

The neutral theory of biodiversity purports that patterns in the distribution and abundance of species do not depend on adaptive differences between species (i.e. niche differentiation) but solely on random fluctuations in population size ("ecological drift"), along with dispersal and speciation. In this framework, the ultimate driver of biodiversity is speciation. However, the original neutral theory made strongly simplifying assumptions about the mechanisms of speciation, which has led to some clearly unrealistic predictions. In response, several recent studies have combined neutral community models with more elaborate speciation models. These efforts have alleviated some of the problems of the earlier approaches, while confirming the general ability of neutral theory to predict empirical patterns of biodiversity. However, the models also show that the mode of speciation can have a strong impact on relative species abundances. Future work should compare these results to diversity patterns arising from non-neutral modes of speciation, such as adaptive radiations.


Assuntos
Biodiversidade , Modelos Biológicos , Animais , Dinâmica Populacional , Especificidade da Espécie
18.
Int J Drug Policy ; 103: 103613, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35255391

RESUMO

BACKGROUND: People who use illicit drugs (PWUD) remain at significantly elevated risk for HIV infection and continue to have very low testing rates. HIV self-testing (HIVST) has been shown to be acceptable among many high-risk populations, but less is known about PWUD. METHODS: From May-June 2021, a HIVST program was implemented at a syringe services program (SSP) in Louisville, Kentucky. PWUD were given the option to privately self-test at the SSP or take the test home and follow-up with study staff. Primary outcomes were acceptability, ease of use, usability, reasons for self-testing, testing location, frequency of future testing, and preference for future testing location. RESULTS: Among 230 study participants, 77% reported high acceptability (i.e., the HIVST kits made them feel much more able to keep track of their HIV status compared to standard testing methods). Virtually all (97.4%) reported the test kits were very easy to use. Problems while using the HIVST kits were rare (range 1.3-3.0%). The most common reasons for testing were a desire to know their status (85.2%), the test was free (37%), and the short duration for results (30.9%). Testing primarily occurred onsite (87.8%). The majority (83%) reported they would use the HIVST kits at least every six months if made available through the health department and would prefer to test at home (71.7%). Multivariate analyses found that awareness of and intention to use pre-exposure prophylaxis (PrEP) were significantly associated with high acceptability and testing onsite. CONCLUSION: Study participants found HIVST to be acceptable and very easy to use. The multivariate findings suggest HIVST interventions should be packaged with PrEP interventions and harm reduction programs.


Assuntos
Infecções por HIV , Drogas Ilícitas , Profilaxia Pré-Exposição , Infecções por HIV/diagnóstico , Infecções por HIV/prevenção & controle , Teste de HIV , Humanos , Programas de Rastreamento , Autoteste
19.
Theor Popul Biol ; 79(3): 82-96, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21192962

RESUMO

We consider a model of sympatric speciation due to frequency-dependent competition, in which it was previously assumed that the evolving traits have a very simple genetic architecture. In the present study, we numerically analyze the consequences of relaxing this assumption. First, previous models assumed that assortative mating evolves in infinitesimal steps. Here, we show that the range of parameters for which speciation is possible increases when mutational steps are large. Second, it was assumed that the trait under frequency-dependent selection is determined by a single locus with two alleles and additive effects. As a consequence, the resultant intermediate phenotype is always heterozygous and can never breed true. To relax this assumption, here we add a second locus influencing the trait. We find three new possible evolutionary outcomes: evolution of three reproductively isolated species, a monomorphic equilibrium with only the intermediate phenotype, and a randomly mating population with a steep unimodal distribution of phenotypes. Both extensions of the original model thus increase the likelihood of competitive speciation.


Assuntos
Evolução Molecular , Modelos Genéticos , Animais , Ecologia , Feminino , Masculino
20.
Wien Klin Wochenschr ; 133(21-22): 1131-1136, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34528125

RESUMO

BACKGROUND: The addition of cisplatin or cetuximab to radiotherapy in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN) has significantly improved the outcome. While the superiority of cisplatin over cetuximab in combination with radiotherapy has been shown in a definitive setting, we set out to compare postoperative chemoradiotherapy with cisplatin to radioimmunotherapy with cetuximab and radiotherapy alone within the Austrian head and neck cancer registry of the Working Group on Pharmaceutical Tumor Treatment (AGMT) study group. MATERIAL AND METHODS: In the AGMT head and neck cancer registry, data of 557 patients with SCCHN from five Austrian cancer centers were prospectively collected between 2012 and 2017. Of these patients 120 received postoperative chemoradiotherapy with cisplatin, 26 patients received postoperative radioimmunotherapy with cetuximab and 56 patients were treated with adjuvant radiotherapy only. Patient characteristics, stage of disease, details on treatment as well as survival were analyzed by a chart-based review. RESULTS: In patients treated with postoperative radiotherapy the addition of cisplatin significantly improved progression-free survival (PFS) and overall survival (OS) compared to cetuximab (PFS 84.2 months vs. 17.0 months, p = 0.04, OS not reached vs. 46.0 months, p = 0.02) and PFS compared to radiotherapy alone (PFS 84.2 months vs. 28.5 months, p < 0.01). Patients treated with cetuximab were significantly older and had a worse performance score than patients receiving cisplatin or radiotherapy alone. CONCLUSION: This study confirmed the importance of multimodal treatment concepts in patients with locally advanced SCCHN. Postoperative cetuximab might be an option in patients not eligible for high-dose cisplatin but cisplatin should remain the standard of care.


Assuntos
Cisplatino , Neoplasias de Cabeça e Pescoço , Áustria , Cetuximab , Quimiorradioterapia , Humanos , Radioimunoterapia , Sistema de Registros
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