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1.
Opt Lett ; 49(5): 1321-1324, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38427003

RESUMO

A phase-matching-free ultrashort pulse retrieval based on the defocusing of a laser-induced plasma is presented. In this technique, a pump pulse ionizes a rare gas providing a plasma lens whose creation time is ultrafast. A probe pulse propagating through this gas lens experiences a switch of its divergence. The spectrum of the diverging part, isolated by a coronograph, is measured as a function of the pump-probe delay, providing a spectrogram that allows for a comprehensive characterization of the temporal properties of the probe pulse. The method, called PI-FROSt for "plasma-induced frequency-resolved optical switching," is simple, is free of phase-matching constraints, and can operate in both self- and cross-referenced configurations at ultrahigh repetition rate in the whole transparency range of the gas. The assessment of the method demonstrates laser pulse reconstructions of high reliability in both near-infrared (NIR) and ultraviolet (UV) spectral ranges.

2.
J Int Bioethique Ethique Sci ; 34(3): 103-124, 2024.
Artigo em Francês | MEDLINE | ID: mdl-38423970

RESUMO

The idea of collaborative governance is gaining popularity. However, how can it be truly collaborative? Decision-making systems with diverse stakeholders must deal with different positions, roles, interests, missions, observations, and values. The co P·R·I·M·O·V (Position, Role, Interest, Mission, Observation, Values) bioethics tool aims to improve the practice of sustainable, collaborative, and democratic development of technosocial initiatives through its user-friendly format for professional ethicists. The tool follows the logic of Conflict of Interest (CoI) analysis used in organizational ethics frameworks. CoI, as an analytical unit in ethics, allows the anticipation and management of problems that may compromise the short- and long-term activities of a program and its governance. This tool was built on a case study for the implementation of monitoring of antibiotic use in animal health in Quebec, Canada. The use of this bioethics tool is strategic and can help negotiate positions and thus co-construct a common frame of reference between the stakeholders in view of a collaborative governance favoring cooperation.


Assuntos
Bioética , Humanos , Eticistas , Canadá , Quebeque
3.
Glob Chang Biol ; 30(1): e16991, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37905464

RESUMO

Sea turtles are vulnerable to climate change since their reproductive output is influenced by incubating temperatures, with warmer temperatures causing lower hatching success and increased feminization of embryos. Their ability to cope with projected increases in ambient temperatures will depend on their capacity to adapt to shifts in climatic regimes. Here, we assessed the extent to which phenological shifts could mitigate impacts from increases in ambient temperatures (from 1.5 to 3°C in air temperatures and from 1.4 to 2.3°C in sea surface temperatures by 2100 at our sites) on four species of sea turtles, under a "middle of the road" scenario (SSP2-4.5). Sand temperatures at sea turtle nesting sites are projected to increase from 0.58 to 4.17°C by 2100 and expected shifts in nesting of 26-43 days earlier will not be sufficient to maintain current incubation temperatures at 7 (29%) of our sites, hatching success rates at 10 (42%) of our sites, with current trends in hatchling sex ratio being able to be maintained at half of the sites. We also calculated the phenological shifts that would be required (both backward for an earlier shift in nesting and forward for a later shift) to keep up with present-day incubation temperatures, hatching success rates, and sex ratios. The required shifts backward in nesting for incubation temperatures ranged from -20 to -191 days, whereas the required shifts forward ranged from +54 to +180 days. However, for half of the sites, no matter the shift the median incubation temperature will always be warmer than the 75th percentile of current ranges. Given that phenological shifts will not be able to ameliorate predicted changes in temperature, hatching success and sex ratio at most sites, turtles may need to use other adaptive responses and/or there is the need to enhance sea turtle resilience to climate warming.


Assuntos
Tartarugas , Animais , Tartarugas/fisiologia , Temperatura , Mudança Climática , Reprodução , Razão de Masculinidade
4.
J Dent Res ; 102(11): 1252-1260, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37555395

RESUMO

The capacity of a tissue to continuously alter its phenotype lies at the heart of how an animal is able to quickly adapt to changes in environmental stimuli. Within tissues, differentiated cells are rigid and play a limited role in adapting to new environments; however, differentiated cells are replenished by stem cells that are defined by their phenotypic plasticity. Here we demonstrate that a Wnt-responsive stem cell niche in the junctional epithelium is responsible for the capability of this tissue to quickly adapt to changes in the physical consistency of a diet. Mechanical input from chewing is required to both establish and maintain this niche. Since the junctional epithelium directly attaches to the tooth surface via hemidesmosomes, a soft diet requires minimal mastication, and consequently, lower distortional strains are produced in the tissue. This reduced strain state is accompanied by reduced mitotic activity in both stem cells and their progeny, leading to tissue atrophy. The atrophied junctional epithelium exhibits suboptimal barrier functions, allowing the ingression of bacteria into the underlying connective tissues, which in turn trigger inflammation and mild alveolar bone loss. These data link the mechanics of chewing to the biology of tooth-supporting tissues, revealing how a stem cell niche is responsible for the remarkable adaptability of the junctional epithelium to different diets.


Assuntos
Inserção Epitelial , Gengiva , Animais , Mastigação , Tecido Conjuntivo , Biologia , Epitélio
5.
Vet Comp Oncol ; 21(4): 646-655, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37592810

RESUMO

Osteosarcoma is a highly metastatic primary bone tumour that occurs spontaneously in both pet dogs and humans. Patterns of metastasis to organs beyond the most common site (lung) are poorly characterised and it is unknown whether specific associations between patterns of metastatic progression and patient features exist. This retrospective study characterised the necropsy findings of 83 dogs receiving standardised therapy and clinical monitoring in a prospective clinical trial setting to document patterns of metastasis and correlate outcomes with these patterns and other patient and tumour-specific factors. A total of 20 different sites of metastasis were documented, with lung as the most common site, followed by bone, kidney, liver, and heart. Two distinct clusters of dogs were identified based on patterns of metastasis. There was no significant association between site of enrollment, trial arm, sex, serum alkaline phosphatase (ALP) activity, or tumour location and clinical outcomes. A second cancer type was identified at necropsy in 10 dogs (10/83; 12%). These data showcase the extensive nature of osteosarcoma metastasis beyond the lung and provide a benchmark for clinical monitoring of the disease. Further, this study provides insight into transcriptional features of primary tumours that may relate to a propensity for osteosarcoma metastasis to specific organs and tissues.


Assuntos
Neoplasias Ósseas , Doenças do Cão , Osteossarcoma , Humanos , Cães , Animais , Estudos Retrospectivos , Estudos Prospectivos , Doenças do Cão/patologia , Neoplasias Ósseas/veterinária , Neoplasias Ósseas/patologia , Osteossarcoma/patologia , Osteossarcoma/veterinária
6.
J Dent ; 136: 104652, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37544352

RESUMO

OBJECTIVES: This study compared the surface change on natural and polished enamel exposed to a joint mechanical and chemical wear regimen. METHODS: Human enamel samples were randomly assigned to natural (n = 30) or polished (n = 30) groups, subjected to erosion (n = 10, 0.3% citric acid, 5 min), abrasion (n = 10, 30 s), or a combination (n = 10). Wear in the form of step height was measured with a non-contact profilometer, and surface changes were inspected with SEM on selected sections. Data was normalised and underwent repeated measures MANOVA, accounting for substrate and erosive challenge as independent variables, with Bonferroni correction for significant post hoc interactions. RESULTS: After four cycles, polished samples had mean step heights of 3.08 (0.40) µm after erosion and 4.08 (0.37) µm after erosion/abrasion. For natural samples, these measurements were 1.52 (0.22) µm and 3.62 (0.39) µm, respectively. Natural surfaces displayed less wear than polished surfaces under erosion-only conditions (p<0.0001), but the difference disappeared with added abrasion. SEM revealed a shallow subsurface layer for polished surfaces and natural ones undergoing only erosion. However, natural surfaces exposed to both erosion and abrasion showed deeper subsurface changes up to 50 µm. CONCLUSION: Natural enamel, when exposed to erosion alone, showed less wear and minimal subsurface alterations. But with added abrasion, natural enamel surfaces saw increased wear and notable subsurface changes compared to polished ones. CLINICAL SIGNIFICANCE: The pronounced subsurface lesions observed on eroded/abraded natural enamel surfaces highlight how combined wear challenges may accelerate tooth tissue loss.


Assuntos
Abrasão Dentária , Atrito Dentário , Erosão Dentária , Desgaste dos Dentes , Humanos , Abrasão Dentária/etiologia , Abrasão Dentária/patologia , Erosão Dentária/induzido quimicamente , Erosão Dentária/patologia , Desgaste dos Dentes/etiologia , Escovação Dentária
7.
Nat Commun ; 14(1): 742, 2023 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-36765054

RESUMO

Whether snakes evolved their elongated, limbless bodies or their specialized skulls and teeth first is a central question in squamate evolution. Identifying features shared between extant and fossil snakes is therefore key to unraveling the early evolution of this iconic reptile group. One promising candidate is their unusual mode of tooth replacement, whereby teeth are replaced without signs of external tooth resorption. We reveal through histological analysis that the lack of resorption pits in snakes is due to the unusual action of odontoclasts, which resorb dentine from within the pulp of the tooth. Internal tooth resorption is widespread in extant snakes, differs from replacement in other reptiles, and is even detectable via non-destructive µCT scanning, providing a method for identifying fossil snakes. We then detected internal tooth resorption in the fossil snake Yurlunggur, and one of the oldest snake fossils, Portugalophis, suggesting that it is one of the earliest innovations in Pan-Serpentes, likely preceding limb loss.


Assuntos
Reabsorção de Dente , Dente , Animais , Evolução Biológica , Fósseis/diagnóstico por imagem , Serpentes/anatomia & histologia , Répteis/anatomia & histologia , Dente/diagnóstico por imagem , Filogenia
8.
Microbiol Res ; 266: 127248, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36335804

RESUMO

The effect of a probiotic on gut microbiota depends not only on the species of microorganism but specifically on the strain. In human beings, as in other animals, specific probiotics have been associated with numerous beneficial properties, which include weight modulation (gain or loss), immune modulation, and prevention of many disorders such as lactose intolerance, cardiovascular diseases, and antibiotic-associated diarrhoea. Streptomyces are an essential group of soil bacteria in the Actinomycetes family. They are related to producing a wide range of secondary metabolites known for their beneficial effects on human health. However, according to the human microbiome analysis, a lower prevalence of Streptomyces genus exists than in other non-human microbiomes. This difference can be associated with current lifestyles. In this article, we review the benefits associated with different compounds produced by Streptomyces, with a particular focus on the production of exopolysaccharides, antibiotics, and other secondary metabolites and the potential innovative use of Streptomyces spp. as probiotics.


Assuntos
Microbioma Gastrointestinal , Microbiota , Probióticos , Streptomyces , Animais , Antibacterianos/farmacologia
9.
Function (Oxf) ; 3(5): zqac043, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36168588

RESUMO

Telomerase reverse transcriptase (TERT) (catalytic subunit of telomerase) is linked to the development of coronary artery disease (CAD); however, whether the role of nuclear vs. mitchondrial actions of TERT is involved is not determined. Dominant-negative TERT splice variants contribute to decreased mitochondrial integrity and promote elevated reactive oxygen species production. We hypothesize that a decrease in mitochondrial TERT would increase mtDNA damage, promoting a pro-oxidative redox environment. The goal of this study is to define whether mitochondrial TERT is sufficient to maintain nitric oxide as the underlying mechanism of flow-mediated dilation by preserving mtDNA integrity.Immunoblots and quantitative polymerase chain reaction were used to show elevated levels of splice variants α- and ß-deletion TERT tissue from subjects with and without CAD. Genetic, pharmacological, and molecular tools were used to manipulate TERT localization. Isolated vessel preparations and fluorescence-based quantification of mtH2O2 and NO showed that reduction of TERT in the nucleus increased flow induced NO and decreased mtH2O2 levels, while prevention of mitochondrial import of TERT augmented pathological effects. Further elevated mtDNA damage was observed in tissue from subjects with CAD and initiation of mtDNA repair mechanisms was sufficient to restore NO-mediated dilation in vessels from patients with CAD. The work presented is the first evidence that catalytically active mitochondrial TERT, independent of its nuclear functions, plays a critical physiological role in preserving NO-mediated vasodilation and the balance of mitochondrial to nuclear TERT is fundamentally altered in states of human disease that are driven by increased expression of dominant negative splice variants.


Assuntos
Doença da Artéria Coronariana , Telomerase , Humanos , Telomerase/genética , Peróxido de Hidrogênio/metabolismo , Doença da Artéria Coronariana/genética , Vasodilatação , Oxirredução
10.
Rev Neurol (Paris) ; 178(6): 546-557, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35181159

RESUMO

BACKGROUND: Since 2015, mechanical thrombectomy (MT) is indicated as a treatment for patients with large vessel occlusion (LVO) at the acute phase of ischemic stroke. However, the number of stroke patients eligible for MT is poorly known. OBJECTIVE: The objective of our study was to estimate the number of patients eligible for thrombectomy within the first 24hours of an ischemic stroke, based on the clinical National Institute of Health Stroke Scale (NIHSS). METHOD: Our study concerned all ischemic strokes which occurred between January 2013 and December 2016 recorded in the population-based Brest Stroke Registry (BSR). Based on positive predictive value and negative predictive value from articles evaluating the performance of a defined NIHSS threshold to identify LVO, we first estimated the frequency of patients with LVO and then the frequency of patients eligible for MT depending on pre-stroke modified Rankin score (mRS). Our results were extrapolated to regions of metropolitan France. Two scenarios were considered: one called "stringent criteria" with mRS ≤1 and one called "real-life" criteria with mRS ≤2. RESULT: We analyzed data from 2,025 ischemic strokes with symptom onset ≤24hours. No statistical difference between patient characteristics according to the time of hospital admission (≤6H vs. 6-24H) was observed. Based on NIHSS scores, between 23.90% and 44.20% of ischemic strokes admitted within the first six hours had LVO clinical characteristics. Among them, 14.53% to 26.87% met the ``stringent eligibility'' criteria for MT and 16.9 to 31.25% for ``real-life'' criteria. Eligible patients represented 6.32% to 11.70% of all ischemic strokes, irrespective of admission time. In France, 75 to 162 persons per million inhabitants per year were eligible for endovascular therapy, depending on including criteria. Based on activity levels recorded by the French Neuroradiology Society (SFNR) in 2018, the estimated needed increase in MT showed a heterogeneous pattern region-by-region, with the greatest need in Brittany, Pays de la Loire, and Corsica. CONCLUSION: Based on NIHSS, our study provides coherent information concerning the estimated number of MT procedures to be performed in France: 4,877 to 10,494 ischemic strokes would be eligible each year in metropolitan France compared to the 6,596 thrombectomy procedures actually performed in 2018. Depending on the region, an estimated 10-20% to 90-100% increase in MT activity would be necessary to meet patient needs. These data suggest that there is still room for improvement in thrombectomy activity, particularly in certain regions of France, to allow equal access to MT to the entire French population.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/epidemiologia , Isquemia Encefálica/cirurgia , Humanos , Sistema de Registros , Estudos Retrospectivos , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/cirurgia , Trombectomia/métodos , Resultado do Tratamento
11.
Child Abuse Negl ; 116(Pt 2): 104761, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33077248

RESUMO

BACKGROUND: The ecosystemic approach to children's needs demands a cohesive response from societies, communities, and families. During the COVID-19 pandemic, the choices societies made to protect their community members from the virus could have created contexts of child neglect. With the closure of services and institutions, societies were no longer available to help meet the needs of children. OBJECTIVE: The purpose of this study is to examine parents' reports on the response their children received to their needs during the COVID-19 crisis. METHODS: During the period of the spring 2020 lockdown, 414 parents in the province of Quebec, Canada, completed an online questionnaire about the impact of the crisis on the response their children received to their needs. RESULTS: Compared to parents of younger children, parents of older children reported less fulfillment of their child's needs in three measured domains, namely cognitive and affective, security, and basic care needs. CONCLUSION: These results are discussed in light of the policies and the resources societies have put in place during the crisis to help families meet the needs of their children. Societies must learn from this crisis to put children at the top of their priorities in the face of a societal crisis. Thoughtful discussions and energy must be given to ensure that, while facing a crisis, the developmental trajectories of children are not sacrificed.


Assuntos
COVID-19 , Maus-Tratos Infantis , Meio Social , Adolescente , Adulto , Canadá , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pandemias , Pais/psicologia , Quebeque , SARS-CoV-2 , Inquéritos e Questionários
12.
J Appl Microbiol ; 130(5): 1412-1424, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-32955761

RESUMO

Lactic acid bacteria (LAB), widely used as starter cultures for the fermentation of a large variety of food, can improve the safety, shelf life, nutritional value and overall quality of the fermented products. In this regard, the selection of strains delivering health-promoting compounds is now the main objective of many researchers. Although most LAB are auxotrophic for several vitamins, it is known that certain strains have the capability to synthesize B-group vitamins. This is an important property since humans cannot synthesize most vitamins, and these could be obtained by consuming LAB fermented foods. This review discusses the use of LAB as an alternative to fortification by the chemical synthesis to increase riboflavin and folate concentrations in food. Moreover, it provides an overview of the recent applications of vitamin-producing LAB with anti-inflammatory/antioxidant activities against gastrointestinal tract inflammation. This review shows the potential uses of riboflavin and folates producing LAB for the biofortification of food, as therapeutics against intestinal pathologies and to complement anti-inflammatory/anti-neoplastic treatments.


Assuntos
Ácido Fólico/biossíntese , Alimentos Fortificados , Doenças Inflamatórias Intestinais/terapia , Lactobacillales/metabolismo , Mucosite/terapia , Riboflavina/biossíntese , Animais , Antioxidantes/análise , Fermentação , Alimentos Fermentados , Ácido Fólico/análise , Humanos , Lactobacillales/isolamento & purificação , Riboflavina/análise , Vitaminas/análise , Vitaminas/biossíntese
13.
Appl Microbiol Biotechnol ; 105(1): 327-340, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33205285

RESUMO

Chemotherapy is the most common treatment for breast cancer and its metastasis; however, it affects the patients' quality of life. Previously, it was demonstrated that milk fermented by Lactobacillus casei CRL431 (probiotic fermented milk (PFM)) exerted benefits against breast cancer metastasis by modulating the immune response in a mouse model. The aim of this work was to evaluate PFM administration on the side effects of capecitabine and on its anti-tumour/anti-metastatic effects. In vitro, 4T1 breast cancer cells were treated with capecitabine in the presence of immune cells' conditioned media from mice administered with PFM. Cell viability was evaluated by MTT assay. In vivo, BALB/c mice (healthy, bearing breast cancer or with potential metastasis) were treated or not with capecitabine and administered with PFM. Blood cell counts, intestinal damages, lung histology and serum cytokines were evaluated. Results showed that capecitabine's toxicity on 4T1 cells was improved by the immune cells from mice that received PFM when the lower dose of capecitabine was evaluated. PFM reduced capecitabine side effects in all the mouse models and decreased intestinal mucositis and mortality. PFM administration to mice under chemotherapy maintained the anti-cancer/anti-metastasis effect of capecitabine with similar or decreased values for serum IL-10 and TNF-α and decreased IL-6, a cytokine related to poor prognosis in advanced cancer patients. In addition, PFM by itself reduced metastasis without side effects and improved the host's immune response. PFM has a potential to be administered as an immune adjuvant in patients under chemotherapy without affecting the treatment. KEY POINTS: • Milk fermented by L. casei CRL431 (PFM) diminished capecitabine side effects. • Capecitabine's toxicity on 4T1 cells was improved by the PFM-stimulated immune cells. • PFM maintained anti-cancer/anti-metastasis effect of capecitabine in mouse models. Graphical abstract.


Assuntos
Neoplasias da Mama , Lacticaseibacillus casei , Probióticos , Animais , Neoplasias da Mama/tratamento farmacológico , Fermentação , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Leite , Qualidade de Vida
14.
Neuropsychopharmacology ; 46(3): 579-602, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32781459

RESUMO

Maternal immune activation (MIA) and poor maternal nutritional habits are risk factors for the occurrence of neurodevelopmental disorders (NDD). Human studies show the deleterious impact of prenatal inflammation and low n-3 polyunsaturated fatty acid (PUFA) intake on neurodevelopment with long-lasting consequences on behavior. However, the mechanisms linking maternal nutritional status to MIA are still unclear, despite their relevance to the etiology of NDD. We demonstrate here that low maternal n-3 PUFA intake worsens MIA-induced early gut dysfunction, including modification of gut microbiota composition and higher local inflammatory reactivity. These deficits correlate with alterations of microglia-neuron crosstalk pathways and have long-lasting effects, both at transcriptional and behavioral levels. This work highlights the perinatal period as a critical time window, especially regarding the role of the gut-brain axis in neurodevelopment, elucidating the link between MIA, poor nutritional habits, and NDD.


Assuntos
Ácidos Graxos Ômega-3 , Efeitos Tardios da Exposição Pré-Natal , Animais , Comportamento Animal , Encéfalo , Feminino , Humanos , Inflamação , Microglia , Gravidez
15.
J Appl Microbiol ; 130(6): 2063-2074, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33128836

RESUMO

AIMS: To evaluate a mixture of selected lactic acid bacteria (LAB) (a riboflavin-producer, a folate-producer and an immunomodulatory strain) as co-adjuvant for 5-fluorouracil (5-FU) chemotherapy in cell culture and using a 4T1 cell animal model of breast cancer. METHODS AND RESULTS: The viability of Caco-2 cells exposed to 5-FU and/or LAB was analysed. Mice bearing breast tumour were treated with 5-FU and/or LAB. Tumour growth was measured. Intestinal mucositis (IM) was evaluated in small intestine; haematological parameters and plasma cytokines were determined. The bacterial mixture did not negatively affect the cytotoxic activity of 5-FU on Caco-2 cells. The LAB mixture attenuated the IM and prevented blood cell decreases associated with 5-FU treatment. Mice that received 5-FU and LAB mixture decreased tumour growth and showed modulation of systemic cytokines modified by both tumour growth and 5-FU treatment. The LAB mixture by itself delayed tumour growth. CONCLUSIONS: The mixture of selected LAB was able to reduce the side-effects associated with chemotherapy without affecting its primary anti-tumour activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This bacterial mixture could prevent the interruption of conventional oncologic therapies by reducing undesirable side-effects. In addition, this blend would provide essential nutrients (vitamins) to oncology patients.


Assuntos
Adjuvantes Imunológicos , Neoplasias da Mama/terapia , Fluoruracila/uso terapêutico , Lactobacillales/imunologia , Lactobacillales/metabolismo , Animais , Antineoplásicos/uso terapêutico , Células CACO-2 , Linhagem Celular , Sobrevivência Celular , Citocinas/sangue , Modelos Animais de Doenças , Feminino , Ácido Fólico/metabolismo , Humanos , Imunomodulação , Mucosa Intestinal/microbiologia , Mucosa Intestinal/patologia , Camundongos , Camundongos Endogâmicos BALB C , Mucosite/microbiologia , Mucosite/patologia , Riboflavina/metabolismo , Vitaminas
16.
Biol Lett ; 16(12): 20200750, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33321067

RESUMO

Theropod dinosaurs are well known for having a ziphodont dentition: serrated, blade-shaped teeth that they used for cutting through prey. Serrations along the carinae of theropod teeth are composed of true denticles, a complex arrangement of dentine, enamel, and interdental folds. This structure would have supported individual denticles and dissipated the stresses associated with feeding. These particular serrations were previously thought to be unique to theropod dinosaurs and some other archosaurs. Here, we identify the same denticles and interdental folds forming the cutting edges in the teeth of a Permian gorgonopsian synapsid, extending the temporal and phylogenetic distribution of this dental morphology. This remarkable instance of convergence not only represents the earliest record of this adaptation to hypercarnivory but also demonstrates that the first iteration of this feature appeared in non-mammalian synapsids. Comparisons of tooth serrations in gorgonopsians with those of earlier synapsids and hypercarnivorous mammals reveal some gorgonopsians acquired a complex tissue arrangement that differed from other synapsids.


Assuntos
Dinossauros , Dente , Animais , Evolução Biológica , Dinossauros/anatomia & histologia , Fósseis , Mamíferos , Filogenia
17.
Opt Express ; 28(12): 17161-17170, 2020 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-32679929

RESUMO

We present a novel approach for measuring the carrier-envelope phase (CEP) stability of a laser source by employing the process of high harmonic generation (HHG) in solids. HHG in solids driven by few-cycle pulses is very sensitive to the waveform of the driving pulse, therefore enabling to track the shot-to-shot CEP fluctuations of a laser source. This strategy is particularly practical for pulses at long central wavelength up to the mid-infrared spectral range where usual techniques used in the visible or near-infrared regions are challenging to transpose. We experimentally demonstrate this novel tool by measuring the CEP fluctuations of a mid-infrared laser source centered at 9.5~µm.

18.
Opt Lett ; 45(8): 2267-2270, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32287210

RESUMO

We present a novel, to the best of our knowledge, approach for scaling the peak power of mid-infrared laser pulses with few-cycle duration and carrier-to-envelope phase stabilization. Using frequency domain optical parametric amplification (FOPA), selective amplification is performed on two spectral slices of broadband pulses centered at 1.8 µm wavelength. In addition to amplification, the Fourier plane is used for specific pulse shaping to control both the relative polarization and the phase/delay between the two spectral slices of the input pulses. At the output of the FOPA, intrapulse difference frequency generation provides carrier-envelope phase stabilized two-cycle pulses centered at 9.5 µm wavelength with 25.5 µJ pulse energy. The control of the carrier-envelope phase is demonstrated through the dependence of high-harmonic generation in solids. This architecture is perfectly adapted to be scaled in the future to high average and high peak powers using picosecond ytterbium laser technologies.

19.
Cancer Metab ; 8: 4, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32158544

RESUMO

BACKGROUND: Osteosarcoma (OS) is a malignant bone tumor that often develops during the period of rapid growth associated with adolescence. Despite successful primary tumor control accompanied by adjuvant chemotherapy, death from pulmonary metastases occurs in approximately 30% of patients within 5 years. As overall survival in patients remains unchanged over the last 30 years, urgent needs for novel therapeutic strategies exist. Cancer metastasis is characterized by complex molecular events which result from alterations in gene and protein expression/function. Recent studies suggest that metabolic adaptations, or "metabolic reprogramming," may similarly contribute to cancer metastasis. The goal of this study was to specifically interrogate the metabolic vulnerabilities of highly metastatic OS cell lines in a series of in vitro and in vivo experiments, in order to identify a tractable metabolically targeted therapeutic strategy for patients. METHODS: Nutrient deprivation and drug treatment experiments were performed in MG63.3, 143B, and K7M2 OS cell lines to identify the impact of glutaminase-1 (GLS1) inhibition and metformin treatment on cell proliferation. We functionally validated the impact of drug treatment with extracellular flux analysis, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry. 13C-glucose and 13C-glutamine tracing was employed to identify specific contributions of these nutrients to the global metabolic profiles generated with GLS1 inhibition and metformin treatment in vivo. RESULTS: Highly metastatic OS cell lines require glutamine for proliferation, and exposure to CB-839, in combination with metformin, induces both primary tumor growth inhibition and a distinct reduction in metastatic outgrowth in vivo. Further, combination-treated OS cells showed a reduction in cellular mitochondrial respiration, while NMR confirmed the pharmacodynamic effects of glutaminase inhibition in tumor tissues. We observed global decreases in glycolysis and tricarboxylic acid (TCA) cycle functionality, alongside an increase in fatty acid oxidation and pyrimidine catabolism. CONCLUSIONS: This data suggests combination-treated cells cannot compensate for metformin-induced electron transport chain inhibition by upregulating glutaminolysis to generate TCA cycle intermediates required for cell proliferation, translating into significant reductions in tumor growth and metastatic progression. This therapeutic approach could be considered for future clinical development for OS patients presenting with or at high risk of developing metastasis.

20.
Opt Express ; 27(20): 28998-29015, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31684642

RESUMO

In this paper, we introduce a pulse characterization technique that is free of phase-matching constraints, exploiting transient absorption in solids as an ultrafast optical switch. Based on a pump-probe setup, this technique uses pump pulses of sufficient intensity to induce the switch, while the pulses to characterize are probing the transmissivity drop of the photoexcited material. This enables the characterization of low-intensity ultra-broadband pulses at the detection limit of the spectrometer and within the transparency range of the solid. For example, by using zinc selenide (ZnSe), pulses with wavelengths from 0.5 to 20 µm can be characterized, denoting five octaves of spectral range. Using ptychography, we retrieve the temporal profiles of both the probe pulse and the switch. To demonstrate this approach, we measure ultrashort pulses from a titanium-sapphire (Ti-Sa) amplifier, which are compressed using a hollow core fiber setup, as well as infrared to mid-infrared pulses generated from an optical parametric amplifier (OPA). The characterized pulses are centered at wavelengths of 0.77, 1.53, 1.75, 4, and 10 µm, down to sub-two optical cycles duration, exceeding an octave of bandwidth, and with energy as low as a few nanojoules.

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