Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 359
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Nature ; 629(8012): 567-572, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38720079

RESUMO

Entanglement has evolved from an enigmatic concept of quantum physics to a key ingredient of quantum technology. It explains correlations between measurement outcomes that contradict classical physics and has been widely explored with small sets of individual qubits. Multi-partite entangled states build up in gate-based quantum-computing protocols and-from a broader perspective-were proposed as the main resource for measurement-based quantum-information processing1,2. The latter requires the ex-ante generation of a multi-qubit entangled state described by a graph3-6. Small graph states such as Bell or linear cluster states have been produced with photons7-16, but the proposed quantum-computing and quantum-networking applications require fusion of such states into larger and more powerful states in a programmable fashion17-21. Here we achieve this goal by using an optical resonator22 containing two individually addressable atoms23,24. Ring25 and tree26 graph states with up to eight qubits, with the names reflecting the entanglement topology, are efficiently fused from the photonic states emitted by the individual atoms. The fusion process itself uses a cavity-assisted gate between the two atoms. Our technique is, in principle, scalable to even larger numbers of qubits and is the decisive step towards, for instance, a memory-less quantum repeater in a future quantum internet27-29.

2.
Cell ; 156(1-2): 146-57, 2014 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-24439374

RESUMO

Misfolded proteins are often cytotoxic, unless cellular systems prevent their accumulation. Data presented here uncover a mechanism by which defects in secretory proteins lead to a dramatic reduction in their mRNAs and protein expression. When mutant signal sequences fail to bind to the signal recognition particle (SRP) at the ribosome exit site, the nascent chain instead contacts Argonaute2 (Ago2), and the mutant mRNAs are specifically degraded. Severity of signal sequence mutations correlated with increased proximity of Ago2 to nascent chain and mRNA degradation. Ago2 knockdown inhibited degradation of the mutant mRNA, while overexpression of Ago2 or knockdown of SRP54 promoted degradation of secretory protein mRNA. The results reveal a previously unappreciated general mechanism of translational quality control, in which specific mRNA degradation preemptively regulates aberrant protein production (RAPP).


Assuntos
Biossíntese de Proteínas , Dobramento de Proteína , Estabilidade de RNA , Partícula de Reconhecimento de Sinal/metabolismo , Sequência de Aminoácidos , Animais , Proteínas Argonautas/metabolismo , Cães , Células HeLa , Humanos , Dados de Sequência Molecular , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alinhamento de Sequência
3.
Nature ; 608(7924): 677-681, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-36002484

RESUMO

The central technological appeal of quantum science resides in exploiting quantum effects, such as entanglement, for a variety of applications, including computing, communication and sensing1. The overarching challenge in these fields is to address, control and protect systems of many qubits against decoherence2. Against this backdrop, optical photons, naturally robust and easy to manipulate, represent ideal qubit carriers. However, the most successful technique so far for creating photonic entanglement3 is inherently probabilistic and, therefore, subject to severe scalability limitations. Here we report the implementation of a deterministic protocol4-6 for the creation of photonic entanglement with a single memory atom in a cavity7. We interleave controlled single-photon emissions with tailored atomic qubit rotations to efficiently grow Greenberger-Horne-Zeilinger (GHZ) states8 of up to 14 photons and linear cluster states9 of up to 12 photons with a fidelity lower bounded by 76(6)% and 56(4)%, respectively. Thanks to a source-to-detection efficiency of 43.18(7)% per photon, we measure these large states about once every minute, which is orders of magnitude faster than in any previous experiment3,10-13. In the future, this rate could be increased even further, the scheme could be extended to two atoms in a cavity14,15 or several sources could be quantum mechanically coupled16, to generate higher-dimensional cluster states17. Overcoming the limitations encountered by probabilistic schemes for photonic entanglement generation, our results may offer a way towards scalable measurement-based quantum computation18,19 and communication20,21.

4.
Cell ; 148(1-2): 164-74, 2012 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-22265409

RESUMO

Misfolding of ΔF508 cystic fibrosis (CF) transmembrane conductance regulator (CFTR) underlies pathology in most CF patients. F508 resides in the first nucleotide-binding domain (NBD1) of CFTR near a predicted interface with the fourth intracellular loop (ICL4). Efforts to identify small molecules that restore function by correcting the folding defect have revealed an apparent efficacy ceiling. To understand the mechanistic basis of this obstacle, positions statistically coupled to 508, in evolved sequences, were identified and assessed for their impact on both NBD1 and CFTR folding. The results indicate that both NBD1 folding and interaction with ICL4 are altered by the ΔF508 mutation and that correction of either individual process is only partially effective. By contrast, combination of mutations that counteract both defects restores ΔF508 maturation and function to wild-type levels. These results provide a mechanistic rationale for the limited efficacy of extant corrector compounds and suggest approaches for identifying compounds that correct both defective steps.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/química , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Supressão Genética , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Fibrose Cística/genética , Fibrose Cística/terapia , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Humanos , Camundongos , Modelos Moleculares , Dobramento de Proteína , Estrutura Terciária de Proteína
5.
J Chem Phys ; 160(20)2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38804495

RESUMO

Strong coupling between light and molecules is a fascinating topic exploring the implications of the hybridization of photonic and molecular states. For example, many recent experiments have explored the possibility that strong coupling of photonic and vibrational modes might modify chemical reaction rates. In these experiments, reactants are introduced into a planar cavity, and the vibrational mode of a chemical bond strongly couples to one of the many photonic modes supported by the cavity. Some experiments quantify reaction rates by tracking the spectral shift of higher-order cavity modes that are highly detuned from the vibrational mode of the reactant. Here, we show that the spectral position of these cavity modes, even though they are highly detuned, can still be influenced by strong coupling. We highlight the need to consider this strong coupling-induced frequency shift of cavity modes if one is to avoid underestimating cavity-induced reaction rate changes. We anticipate that our work will assist in the re-analysis of several high-profile results and has implications for the design of future strong coupling experiments.

6.
J Appl Microbiol ; 134(8)2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37580171

RESUMO

AIMS: To provide an alternative to ultra violet light and vapourized hydrogen peroxide to enhance decontamination of surfaces as part of the response to the COVID-19 pandemic. METHODS AND RESULTS: We developed an indirect method for in situ delivery of cold plasma and evaluated the anti-viral activity of plasma-activated mist (PAM) using bacteriophages phi6, MS2, and phiX174, surrogates for SARS-CoV-2. Exposure to ambient air atmospheric pressure derived PAM caused a 1.71 log10 PFU ml-1 reduction in phi6 titer within 5 min and a 7.4 log10 PFU ml-1 reduction after 10 min when the the PAM source was at 5 and 10 cm. With MS2 and phiX174, a 3.1 and 1.26 log10 PFU ml-1 reduction was achieved, respectively, after 30 min. The rate of killing was increased with longer exposure times but decreased when the PAM source was further away. Trace amounts of reactive species, hydrogen peroxide and nitrite were produced in the PAM, and the anti-viral activity was probably attributable to these and their secondary reactive species. CONCLUSIONS: PAM exhibits virucidal activity against surrogate viruses for COVID-19, which is time and distance from the plasma source dependent.


Assuntos
Bacteriófagos , Desinfecção , Peróxido de Hidrogênio , Nitritos , Gases em Plasma , Bacteriófagos/efeitos dos fármacos , Bacteriófagos/fisiologia , COVID-19/virologia , Desinfetantes/química , Desinfecção/métodos , Peróxido de Hidrogênio/farmacologia , Nitritos/farmacologia , Gases em Plasma/farmacologia , Espécies Reativas de Nitrogênio/análise , Espécies Reativas de Oxigênio/análise , SARS-CoV-2/fisiologia , Água/química , Microbiologia do Ar
7.
Int J Mol Sci ; 24(2)2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36674498

RESUMO

The relationship between sleep and micronutrients, including magnesium, is implicated in its regulation. The effects of low magnesium and other micronutrients on sleep disruption and telomere loss are not well understood. The present study was carried out in 172 healthy elderly subjects from South Australia. Plasma micronutrients including magnesium were measured. Each participant provided information about their sleep hours (<7 h or ≥7 h). Lymphocyte telomere length (TL) was measured by real-time qPCR assay. Plasma magnesium level was significantly low in subjects who sleep less than 7 h (p = 0.0002). TL was significantly shorter in people who are low in magnesium and sleep less than 7 h (p = 0.01). Plasma homocysteine (Hcy) is negatively associated with magnesium (r = −0.299; p < 0.0001). There is a significant interaction effect of magnesium and Hcy on sleep duration (p = 0.04) and TL (p = 0.003). Our results suggest that inadequate magnesium levels have an adverse impact on sleep and telomere attrition rate in cognitively normal elderly people, and this may be exacerbated by low levels of vitamin B12 and folate that elevate Hcy concentration.


Assuntos
Magnésio , Vitamina B 12 , Humanos , Idoso , Austrália , Ácido Fólico , Telômero/genética , Sono , Micronutrientes , Homocisteína
8.
Int J Mol Sci ; 24(18)2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37762467

RESUMO

Nutritional imbalances have been associated with a higher risk for cognitive impairment. This study determined the red blood cell (RBC) fatty acid profile of newly diagnosed mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients compared to age and gender-matched controls. There was a significant increase in palmitic acid (p < 0.00001) for both MCI and AD groups. Saturated fatty acids were significantly elevated in the MCI group, including stearic acid (p = 0.0001), arachidic acid (p = 0.003), behenic acid (p = 0.0002), tricosanoic acid (p = 0.007) and lignoceric acid (p = 0.001). n-6 polyunsaturated fatty acids (PUFAs) were significantly reduced in MCI, including linoleic acid (p = 0.001), γ-linolenic acid (p = 0.03), eicosatrienoic acid (p = 0.009) and arachidonic acid (p < 0.00004). The n-3 PUFAs, α-linolenic acid and docosahexaenoic acid, were both significantly reduced in MCI and AD (p = 0.0005 and p = 0.00003). A positive correlation was evident between the Mini-Mental State Examination score and nervonic acid in MCI (r = 0.54, p = 0.01) and a negative correlation with γ-linolenic acid in AD (r = -0.43, p = 0.05). Differences in fatty acid profiles may prove useful as potential biomarkers reflecting increased risk for dementia.

9.
Phys Rev Lett ; 126(13): 130502, 2021 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33861090

RESUMO

Quantum teleportation enables the deterministic exchange of qubits via lossy channels. While it is commonly believed that unconditional teleportation requires a preshared entangled qubit pair, here we demonstrate a protocol that is in principle unconditional and requires only a single photon as an ex-ante prepared resource. The photon successively interacts, first, with the receiver and then with the sender qubit memory. Its detection, followed by classical communication, heralds a successful teleportation. We teleport six mutually unbiased qubit states with average fidelity F[over ¯]=(88.3±1.3)% at a rate of 6 Hz over 60 m.

10.
Phys Rev Lett ; 126(25): 253603, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34241514

RESUMO

Nondestructive quantum measurements are central for quantum physics applications ranging from quantum sensing to quantum computing and quantum communication. Employing the toolbox of cavity quantum electrodynamics, we here concatenate two identical nondestructive photon detectors to repeatedly detect and track a single photon propagating through a 60 m long optical fiber. By demonstrating that the combined signal-to-noise ratio of the two detectors surpasses each single one by about 2 orders of magnitude, we experimentally verify a key practical benefit of cascaded nondemolition detectors compared to conventional absorbing devices.

11.
J Chem Phys ; 154(2): 024704, 2021 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-33445885

RESUMO

Strong coupling between surface plasmons and molecular excitons may lead to the formation of new hybrid states-polaritons-that are part light and part matter in character. A key signature of this strong coupling is an anti-crossing of the exciton and surface plasmon modes on a dispersion diagram. In a recent report on strong coupling between the plasmon modes of a small silver nano-rod and a molecular dye, it was shown that when the oscillator strength of the exciton is large enough, an additional anti-crossing feature may arise in the spectral region where the real part of the permittivity of the excitonic material is zero. However, the physics behind this double anti-crossing feature is still unclear. Here, we make use of extensive transfer matrix simulations to explore this phenomenon. We show that for low oscillator strengths of the excitonic resonance, there is a single anti-crossing arising from strong coupling between the surface plasmon and the excitonic resonance, which is associated with the formation of upper and lower plasmon-exciton polaritons. As the oscillator strength is increased, we find that a new mode emerges between these upper and lower polariton states and show that this new mode is an excitonic surface mode. Our study also features an exploration of the role played by the orientation of the excitonic dipole moment and the relationship between the modes we observe and the transverse and longitudinal resonances associated with the excitonic response. We also investigate why this type of double splitting is rarely observed in experiments.

12.
Nano Lett ; 20(9): 6412-6419, 2020 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-32709208

RESUMO

Light-matter interactions can occur when an ensemble of molecular resonators is placed in a confined electromagnetic field. In the strong coupling regime the rapid exchange of energy between the molecules and the electromagnetic field results in the emergence of hybrid light-matter states called polaritons. Multiple criteria exist to define the strong coupling regime, usually by comparing the splitting of the polariton bands with the line widths of the uncoupled modes. Here, we highlight the limitations of these criteria and study strong coupling using spectroscopic ellipsometry, a commonly used optical characterization technique. We identify a new signature of strong coupling in ellipsometric phase spectra. The combination of ellipsometric amplitude and phase spectra yields a distinct topological feature that we suggest could serve as a new criterion for strong coupling. Our results introduce the idea of ellipsometric topology and could provide further insight into the transition from the weak to strong coupling regime.

13.
J Stroke Cerebrovasc Dis ; 30(6): 105757, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33873077

RESUMO

OBJECTIVES: Accurate and timely diagnosis of pneumonia complicating stroke remains challenging and the diagnostic accuracy of chest X-ray (CXR) in the setting of stroke-associated pneumonia (SAP) is uncertain. The overall objective of this study was to evaluate the use of pulmonary computed tomography (CT) in diagnosis of suspected SAP. MATERIALS AND METHODS: Patients with acute ischemic stroke (IS) or intracerebral hemorrhage (ICH) were recruited within 24h of clinically suspected SAP and underwent non-contrast pulmonary CT within 48h of antibiotic initiation. CXR and pulmonary CT were reported by two radiologists. Pulmonary CT was used as the reference standard for final diagnosis of SAP. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and diagnostic odds ratio (OR) for CXR were calculated. RESULTS: 40 patients (36 IS, 4 ICH) with a median age of 78y (range 44y-90y) and a median National Institute of Health Stroke Scale score of 13 (range 3-31) were included. All patients had at least one CXR and 35/40 patients (88%) underwent pulmonary CT. Changes consistent with pneumonia were present in 15/40 CXRs (38%) and 12/35 pulmonary CTs (34%). 9/35 pulmonary CTs (26%) were reported normal. CXR had a sensitivity of 58.3%, specificity of 73.9%, PPV of 53.8 %, NPV of 77.2 %, diagnostic OR of 3.7 (95% CI 0.7 - 22) and an accuracy of 68.5% (95% CI 50.7% -83.1%). DISCUSSION: CXR has limited diagnostic accuracy in SAP. The majority of patients started on antibiotics had no evidence of pneumonia on pulmonary CT with potential implications for antibiotic stewardship. CONCLUSIONS: Pulmonary CT could be applied as a reference standard for evaluation of clinical and biomarker diagnostic SAP algorithms in multi-center studies.


Assuntos
Acidente Vascular Cerebral Hemorrágico/complicações , AVC Isquêmico/complicações , Pulmão/diagnóstico por imagem , Pneumonia/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Gestão de Antimicrobianos , Inglaterra , Feminino , Acidente Vascular Cerebral Hemorrágico/diagnóstico , Humanos , AVC Isquêmico/diagnóstico , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Pneumonia/tratamento farmacológico , Pneumonia/etiologia , Valor Preditivo dos Testes , Estudos Prospectivos , Reprodutibilidade dos Testes
14.
Anthropol Med ; 28(4): 420-428, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34282672

RESUMO

Colonial thinking runs deep in psychiatry. Recent anti-racist statements from the APA and RCPsych are to be welcomed. However, we argue that if it is to really tackle deep-seated racism and decolonise its curriculum, the discipline will need to critically interrogate the origins of some of its fundamental assumptions, values and priorities. This will not be an easy task. By its very nature, the quest to decolonise is fraught with contradictions and difficulties. However, we make the case that this moment presents an opportunity for psychiatry to engage positively with other forms of critical reflection on structures of power/knowledge in the field of mental health. We propose a number of paths along which progress might be made.


Assuntos
Psiquiatria , Racismo , Antropologia Médica , Currículo , Humanos , Saúde Mental
15.
Mol Phylogenet Evol ; 153: 106952, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32889136

RESUMO

The genus Taxus (Taxaceae) consists of 16 genetically well-defined lineages that are predominantly distributed across the Northern hemisphere. We investigated its biogeographic origin and evolutionary history by sampling 13 chloroplast gene sequences, the nuclear internal transcribed spacers (ITS) and NEEDLY sequences for all 16 lineages. We applied Maximum Parsimony and Bayesian Inference analyses to infer their phylogenetic relationships, time-calibrated phylogenies using BEAST and inferred the ancestral area of occupancy with BioGeoBEARS. We found strong evidence for the hybrid origin of three lineages and dated these events to a rather narrow time window of 6.8-4.9 million years ago (Mya). The dated phylogenies inferred an Upper Cretaceous origin of the genus, with the extant lineages diversifying in North America much later during the Oligocene/early Miocene. Repeated migrations via the Bering land bridge to Eurasia and back were further inferred, with the return to North America as a possible result of vicariance. The diversification in Eurasia (from ~8 Mya onwards) coincided with the orogeny of the Hengduan Mountains, the intensification of the East Asian summer monsoon and the occupancy of ecological niches by lineages that experienced secondary contacts and hybridizations in the Hengduan Mountains and Qinling Mountain, especially around the Sichuan basin. We provide a hypothesis for the evolution of extant lineages of Taxus, a genus with an old and complex evolutionary history. The study highlights that the history of complex species can be unravelled with a careful dissection of phylogenetic signals.


Assuntos
Filogenia , Taxus/classificação , Teorema de Bayes , Hibridização Genética , América do Norte , Taxus/genética
16.
J Sex Med ; 17(5): 1033-1040, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32205085

RESUMO

BACKGROUND: Penile inversion vaginoplasty is a commonly performed genital gender-affirming procedure in transgender women. The creation of an adequate functional neovaginal depth in cases of too little usable penile skin is a challenge. The bilateral pedicled epilated scrotal flap (BPES-flap) can be used as an easy adjunctive technique and may serve as a tool in the surgical armamentarium of the gender surgeon. AIM: To describe the use, dissection, design subtypes, and surgical outcomes of the BPES-flap in vaginoplasty. METHODS: Perioperative considerations and different flap design subtypes were described to illustrate the possible uses of the BPES-flap in vaginoplasty. A retrospective chart study was performed on the use of this flap in 3 centers (blinded for review purposes). OUTCOMES: The main outcome measures are description of surgical technique, flap design possibilities, and postoperative complications. RESULTS: A total of 42 transgender women were included (median age: 28 years (range 18-66), mean body mass index: 24.5 ± 3.5). The mean penile length and width preoperatively were 9 ± 3.1 and 2.9 ± 0.2 cm, respectively. With a mean follow up of 13 ± 10 months, total flap necrosis occurred in one case (2.4%). Partial flap necrosis occurred also in one. Neovaginal reconstruction was successful in all patients with a mean vaginal depth of 13.5 ± 1.3 cm and width of 3.3 ± 1.3 cm. Partial prolapse of the neovaginal top occurred in 3 patients (7%). CLINICAL IMPLICATIONS: The BPES-flap is a useful addition to the arsenal of surgeons performing feminizing genital reconstructive surgery. STRENGTHS & LIMITATIONS: Strenghts comprise (1) the description of the surgical technique with clear images, (2) completeness of data, and (3) that data are from a multicenter study. A weakness is the retrospective nature with limited follow-up time. CONCLUSION: The BPES-flap is a vascularized scrotal flap that can be raised on the bilateral inferior superficial perineal arteries. It may be used for neovaginal depth creation during vaginoplasty and may be quicker to perform than full-thickness skin grafting. Nijhuis THJ, Özer M, van der Sluis WB, et al. The Bilateral Pedicled Epilated Scrotal Flap: A Powerful Adjunctive for Creation of More Neovaginal Depth in Penile Inversion Vaginoplasty. J Sex Med 2020;17:1033-1040.


Assuntos
Cirurgia de Readequação Sexual , Pessoas Transgênero , Transexualidade , Adolescente , Adulto , Idoso , Feminino , Procedimentos Cirúrgicos em Ginecologia , Humanos , Masculino , Pessoa de Meia-Idade , Pênis/cirurgia , Estudos Retrospectivos , Transexualidade/cirurgia , Vagina/cirurgia , Adulto Jovem
17.
Aust N Z J Obstet Gynaecol ; 60(1): 141-148, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31583699

RESUMO

BACKGROUND: Melatonin is a potent oxygen scavenger and is capable of altering blood flow in various vascular beds. AIMS: We aimed to determine the effect of melatonin on ovarian vascular indices during ovarian stimulation for in vitro fertilisation (IVF). MATERIALS AND METHODS: This is a pilot double-blind placebo-controlled randomised trial. Sixty-nine women (mean age 35.8 ± 4.3 years) undergoing their first cycle of IVF were randomised to receive either placebo, 2, 4 or 8 mg of melatonin, twice a day. Each participant underwent a transvaginal ultrasound at days 6-10 assessing follicular number and size. The vascularisation index (VI), flow index (FI) and vascularisation-flow index (VFI) were measured. These indices were then correlated with embryological outcomes. Informed consent was obtained from participants. This trial was registered with the Australia New Zealand Clinical Trials Registry (ACTRN12613001317785). RESULTS: The number of follicles did not differ between groups (P = 0.4). There were no differences in the VI (P = 0.4), FI (P = 0.1) or VFI (P = 0.3) in the right ovary or the FI (P = 0.3) or VFI (P = 0.3) in the left ovary between groups. When comparing placebo to any dose of melatonin, there were no differences in any measured parameter. While there was correlation between the number of follicles on ultrasound and all measured embryological outcomes, there was no correlation between ovarian vascular indices and these important clinical outcomes. CONCLUSIONS: Melatonin does not appear to change ovarian vascular indices during ovarian stimulation. In addition, such vascular indices cannot predict the number or quality of oocytes or embryos obtained in an IVF cycle. These findings require confirmation in future larger studies.


Assuntos
Fertilização in vitro/efeitos dos fármacos , Melatonina/administração & dosagem , Folículo Ovariano/efeitos dos fármacos , Adulto , Biomarcadores , Método Duplo-Cego , Feminino , Humanos , Oócitos/efeitos dos fármacos , Folículo Ovariano/diagnóstico por imagem , Indução da Ovulação , Projetos Piloto , Ultrassonografia , Ultrassonografia Doppler
18.
Cell Physiol Biochem ; 52(1): 141-155, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30790510

RESUMO

BACKGROUND/AIMS: Type 1 Diabetes (T1D) involves autoimmune attack due to reduced regulatory T cells as an effect of mutant Stat5b(C1462A) in non-obese diabetic (NOD) mice, a T1D model resulting in pancreatic ß-cell destruction. Although reactive oxygen species are considered to orchestrate the immune attack, the role of nitric oxide (·NO) still remains debatable. Since JAK-STAT pathway is known to induce Nos2, we investigated the role of STAT5B in nitric oxide generation and oxidative stress. METHODS: In this study, we have used chromatin immunoprecipitation with STAT5B antibody to explore whether STAT5B binds Nos2 promoter. Using Stat5b gene silencing and overexpression models in MIN6 mouse pancreatic ß-cell line we have assayed nitric oxide and its end products, superoxide levels, H2O2 levels, and expression of genes related to redox pathway by immunocytochemistry, biochemical assays, quantitative real time PCR and western blotting. RESULTS: Our results prove that STAT5B binds to the candidate gamma-interferon-activated (GAS) element in Nos2 promoter thereby inducing Nos2 mRNA transcription resulting in NOS2 protein expression in MIN6, a mouse pancreatic ß-cell line. Our findings are substantiated by reduced ·NO as well as nitric oxide end products (nitrate and nitrite), and increased superoxide production in Stat5b silenced MIN6 cells. Our results indicate that C1462A mutant STAT5B shows lack of ·NO generation ability. To detoxify excess superoxide as a consequence of lowered Nos2, an overexpressed SOD2 in Stat5b silenced cells results in increased H2O2 production. H2O2 metabolizing enzymes do not show upregulation upon Stat5b silencing, and thus oxidative stress is brought about by amassed H2O2. Stat5b silencing finally reduces AKT expression, a prosurvival signal. CONCLUSION: Our study enables us to conclude that ß-cell stress is aggravated by the incapability of STAT5B to induce Nos2 resulting in H2O2 accumulation and the ensuing oxidative stress enhances ß-cell damage.


Assuntos
Células Secretoras de Insulina/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico/metabolismo , Fator de Transcrição STAT5/metabolismo , Substituição de Aminoácidos , Animais , Linhagem Celular , Peróxido de Hidrogênio/farmacologia , Camundongos Endogâmicos NOD , Mutação de Sentido Incorreto , Óxido Nítrico/genética , Óxido Nítrico Sintase Tipo II/genética , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Regiões Promotoras Genéticas , Ligação Proteica , Fator de Transcrição STAT5/genética
19.
Ann Bot ; 123(1): 153-167, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30124771

RESUMO

Background and Aims: Rapid evolutionary divergence and reticulate evolution may result in phylogenetic relationships that are difficult to resolve using small nucleotide sequence data sets. Next-generation sequencing methods can generate larger data sets that are better suited to solving these puzzles. One major and long-standing controversy in conifers concerns generic relationships within the subfamily Cupressoideae (105 species, approx. 1/6 of all conifers) of Cupressaceae, in particular the relationship between Juniperus, Cupressus and the Hesperocyparis-Callitropsis-Xanthocyparis (HCX) clade. Here we attempt to resolve this question using transcriptome-derived data. Methods: Transcriptome sequences of 20 species from Cupressoideae were collected. Using MarkerMiner, single-copy nuclear (SCN) genes were extracted. These were applied to estimate phylogenies based on concatenated data, species trees and a phylogenetic network. We further examined the effect of alternative backbone topologies on downstream analyses, including biogeographic inference and dating analysis. Results: Based on the 73 SCN genes (>200 000 bp total alignment length) we considered, all tree-building methods lent strong support for the relationship (HCX, (Juniperus, Cupressus)); however, strongly supported conflicts among individual gene trees were also detected. Molecular dating suggests that these three lineages shared a most recent common ancestor approx. 60 million years ago (Mya), and that Juniperus and Cupressus diverged about 56 Mya. Ancestral area reconstructions (AARs) suggest an Asian origin for the entire clade, with subsequent dispersal to North America, Europe and Africa. Conclusions: Our analysis of SCN genes resolves a controversial phylogenetic relationship in the Cupressoideae, a major clade of conifers, and suggests that rapid evolutionary divergence and incomplete lineage sorting probably acted together as the source for conflicting phylogenetic inferences between gene trees and between our robust results and recently published studies. Our updated backbone topology has not substantially altered molecular dating estimates relative to previous studies; however, application of the latest AAR approaches has yielded a clearer picture of the biogeographic history of Cupressoideae.


Assuntos
Cupressaceae/classificação , Cupressaceae/genética , Proteínas de Plantas/análise , Transcriptoma , Filogenia
20.
Am J Physiol Lung Cell Mol Physiol ; 315(2): L313-L327, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29722564

RESUMO

While primary cystic fibrosis (CF) and non-CF human bronchial epithelial basal cells (HBECs) accurately represent in vivo phenotypes, one barrier to their wider use has been a limited ability to clone and expand cells in sufficient numbers to produce rare genotypes using genome-editing tools. Recently, conditional reprogramming of cells (CRC) with a Rho-associated protein kinase (ROCK) inhibitor and culture on an irradiated fibroblast feeder layer resulted in extension of the life span of HBECs, but differentiation capacity and CF transmembrane conductance regulator (CFTR) function decreased as a function of passage. This report details modifications to the standard HBEC CRC protocol (Mod CRC), including the use of bronchial epithelial cell growth medium, instead of F medium, and 2% O2, instead of 21% O2, that extend HBEC life span while preserving multipotent differentiation capacity and CFTR function. Critically, Mod CRC conditions support clonal growth of primary HBECs from a single cell, and the resulting clonal HBEC population maintains multipotent differentiation capacity, including CFTR function, permitting gene editing of these cells. As a proof-of-concept, CRISPR/Cas9 genome editing and cloning were used to introduce insertions/deletions in CFTR exon 11. Mod CRC conditions overcome many barriers to the expanded use of HBECs for basic research and drug screens. Importantly, Mod CRC conditions support the creation of isogenic cell lines in which CFTR is mutant or wild-type in the same genetic background with no history of CF to enable determination of the primary defects of mutant CFTR.


Assuntos
Brônquios/metabolismo , Diferenciação Celular , Fibrose Cística/metabolismo , Células-Tronco Multipotentes/metabolismo , Células 3T3 , Animais , Brônquios/patologia , Sistemas CRISPR-Cas , Técnicas de Cultura de Células , Células Cultivadas , Técnicas de Reprogramação Celular , Fibrose Cística/tratamento farmacológico , Fibrose Cística/genética , Fibrose Cística/patologia , Regulador de Condutância Transmembrana em Fibrose Cística , Edição de Genes , Humanos , Camundongos , Células-Tronco Multipotentes/patologia , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa