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1.
Proc Natl Acad Sci U S A ; 118(33)2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34385329

RESUMO

The pairing of homologous chromosomes represents a critical step of meiosis in nearly all sexually reproducing species. In many organisms, pairing involves chromosomes that remain apparently intact. The mechanistic nature of homology recognition at the basis of such pairing is unknown. Using "meiotic silencing by unpaired DNA" (MSUD) as a model process, we demonstrate the existence of a cardinally different approach to DNA homology recognition in meiosis. The main advantage of MSUD over other experimental systems lies in its ability to identify any relatively short DNA fragment lacking a homologous allelic partner. Here, we show that MSUD does not rely on the canonical mechanism of meiotic recombination, yet it is promoted by REC8, a conserved component of the meiotic cohesion complex. We also show that certain patterns of interspersed homology are recognized as pairable during MSUD. Such patterns need to be colinear and must contain short tracts of sequence identity spaced apart at 21 or 22 base pairs. By using these periodicity values as a guiding parameter in all-atom molecular modeling, we discover that homologous DNA molecules can pair by forming quadruplex-based contacts with an interval of 2.5 helical turns. This process requires right-handed plectonemic coiling and additional conformational changes in the intervening double-helical segments. Our results 1) reconcile genetic and biophysical evidence for the existence of direct homologous double-stranded DNA (dsDNA)-dsDNA pairing, 2) identify a role for this process in initiating RNA interference, and 3) suggest that chromosomes can be cross-matched by a precise mechanism that operates on intact dsDNA molecules.


Assuntos
Cromossomos Fúngicos/fisiologia , DNA Fúngico/genética , Regulação Fúngica da Expressão Gênica/fisiologia , Meiose/fisiologia , Neurospora crassa/fisiologia , Recombinação Genética/fisiologia , Cromossomos Fúngicos/genética , Meiose/genética , Recombinação Genética/genética
2.
Cell Commun Signal ; 21(1): 276, 2023 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-37803478

RESUMO

BACKGROUND: Extracellular vesicles (EVs) originating from the central nervous system (CNS) can enter the blood stream and carry molecules characteristic of disease states. Therefore, circulating CNS-derived EVs have the potential to serve as liquid-biopsy markers for early diagnosis and follow-up of neurodegenerative diseases and brain tumors. Monitoring and profiling of CNS-derived EVs using multiparametric analysis would be a major advance for biomarker as well as basic research. Here, we explored the performance of a multiplex bead-based flow-cytometry assay (EV Neuro) for semi-quantitative detection of CNS-derived EVs in body fluids. METHODS: EVs were separated from culture of glioblastoma cell lines (LN18, LN229, NCH82) and primary human astrocytes and measured at different input amounts in the MACSPlex EV Kit Neuro, human. In addition, EVs were separated from blood samples of small cohorts of glioblastoma (GB), multiple sclerosis (MS) and Alzheimer's disease patients as well as healthy controls (HC) and subjected to the EV Neuro assay. To determine statistically significant differences between relative marker signal intensities, an unpaired samples t-test or Wilcoxon rank sum test were computed. Data were subjected to tSNE, heatmap clustering, and correlation analysis to further explore the relationships between disease state and EV Neuro data. RESULTS: Glioblastoma cell lines and primary human astrocytes showed distinct EV profiles. Signal intensities were increasing with higher EV input. Data normalization improved identification of markers that deviate from a common profile. Overall, patient blood-derived EV marker profiles were constant, but individual EV populations were significantly increased in disease compared to healthy controls, e.g. CD36+EVs in glioblastoma and GALC+EVs in multiple sclerosis. tSNE and heatmap clustering analysis separated GB patients from HC, but not MS patients from HC. Correlation analysis revealed a potential association of CD107a+EVs with neurofilament levels in blood of MS patients and HC. CONCLUSIONS: The semi-quantitative EV Neuro assay demonstrated its utility for EV profiling in complex samples. However, reliable statistical results in biomarker studies require large sample cohorts and high effect sizes. Nonetheless, this exploratory trial confirmed the feasibility of discovering EV-associated biomarkers and monitoring circulating EV profiles in CNS diseases using the EV Neuro assay. Video Abstract.


Extracellular vesicles (EVs) are tiny particles released by cells, carrying unique biomolecules specific to their cell of origin. EVs from the central nervous system (CNS) can reach the blood, where they could serve as liquid-biopsy markers for diagnosing brain diseases like neurodegenerative disorders and tumors. This study evaluated a flow cytometry platform (here termed EV Neuro assay), which can detect multiple EV-associated markers simultaneously, to assess its potential for identifying CNS-derived EVs and disease-specific markers in complex samples including the blood. The study compared different sample materials and methods for isolating EVs. We found distinct EV profiles in EVs derived from glioblastoma and human astrocytes, with signal intensities increasing as more EVs were present. Analyzing serum or plasma from patients with brain diseases and healthy individuals, we observed that EV marker intensities were varying between individuals. Importantly, data normalization improved the identification of disease-specific markers, such as CD36+EVs in glioblastoma and GALC+EVs in multiple sclerosis, which were significantly higher in disease compared to healthy controls. Advanced clustering analysis techniques effectively distinguished glioblastoma patients from controls. Furthermore, a potential correlation between CD107a+EVs and neurofilament levels in multiple sclerosis patients was discovered. Overall, the semi-quantitative EV Neuro assay proved useful for profiling EVs in complex samples. However, for more reliable results in biomarker studies, larger sample cohorts and higher effect sizes are necessary. Nonetheless, this initial trial confirmed the potential of the EV Neuro assay for discovering disease-associated EV markers and monitoring circulating EV profiles in CNS diseases.


Assuntos
Vesículas Extracelulares , Glioblastoma , Esclerose Múltipla , Humanos , Glioblastoma/metabolismo , Citometria de Fluxo , Sistema Nervoso Central , Vesículas Extracelulares/metabolismo , Biomarcadores/metabolismo , Esclerose Múltipla/metabolismo
3.
Artigo em Inglês | MEDLINE | ID: mdl-37200213

RESUMO

Strain MDTJ8T is a chain-elongating thermophilic bacterium isolated from a thermophilic acidogenic anaerobic digestor treating human waste while producing the high commodity chemical n-caproate. The strain grows and produces formate, acetate, n-butyrate, n-caproate and lactate from mono-, di- and polymeric saccharides at 37-60 °C (optimum, 50-55 °C) and at pH 5.0-7.0 (optimum, pH 6.5). The organism is an obligate anaerobe, is motile and its cells form rods (0.3-0.5×1.0-3.0 µm) that stain Gram-positive and occur primarily as chains. Phylogenetic analysis of both the 16S rRNA gene and full genome sequence shows that strain MDTJ8T belongs to a group that consists of mesophylic chain-elongating bacteria within the family Oscillospiraceae, being nearest to Caproicibacter fermentans EA1T (94.8 %) and Caproiciproducens galactitolivorans BS-1T (93.7 %). Its genome (1.96 Mbp) with a G+C content of 49.6 mol% is remarkably smaller than those of other chain-elongating bacteria of the family Oscillospiraceae. Pairwise average nucleotide identity and DNA-DNA hybridization values between strain MDJT8T and its mesophilic family members are less than 70 and 35 %, respectively, while pairwise average amino acid identity values are less than 68 %. In addition, strain MDJT8T uses far less carbohydrate and non-carbohydrate substrates compared to its nearest family members. The predominant cellular fatty acids of strain MDTJ8T are C14 : 0, C14 : 0 DMA (dimethyl acetal) and C16 : 0, while its polar lipid profile shows three unidentified glycophospholipids, 11 glycolipids, 13 phospholipids and six unidentified lipids. No respiratory quinones and polyamines are detected. Based on its phylogenetic, genotypic, morphological, physiological, biochemical and chemotaxonomic characteristics, strain MDTJ8T represents a novel species and novel genus of the family Oscillospiraceae and Thermocaproicibacter melissae gen. nov., sp. nov. is proposed as its name. The type strain is MDTJ8T (=DSM 114174T=LMG 32615T=NCCB 100883T).


Assuntos
Ácidos Graxos , Lactobacillales , Humanos , Ácidos Graxos/química , Filogenia , RNA Ribossômico 16S/genética , Caproatos , Composição de Bases , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Análise de Sequência de DNA , Fosfolipídeos/análise , Bactérias Anaeróbias , Polímeros , Lactobacillales/genética
4.
Int J Mol Sci ; 24(11)2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37298421

RESUMO

The gut and the brain communicate via the nervous system, hormones, microbiota-mediated substances, and the immune system. These intricate interactions have led to the term "gut-brain axis". Unlike the brain-which is somewhat protected-the gut is exposed to a variety of factors throughout life and, consequently, might be either more vulnerable or better adapted to respond to these challenges. Alterations in gut function are common in the elder population and associated with many human pathologies, including neurodegenerative diseases. Different studies suggest that changes in the nervous system of the gut, the enteric nervous system (ENS), during aging may result in gastrointestinal dysfunction and initiate human pathologies of the brain via its interconnection with the gut. This review aims at summarizing the contribution of normal cellular aging to the age-associated physiological changes of the ENS. Morphological alterations and degeneration of the aging ENS are observed in different animal models and humans, albeit with considerable variability. The aging phenotypes and pathophysiological mechanisms of the aging ENS have highlighted the involvement of enteric neurons in age-related diseases of the central nervous system such as Alzheimer's or Parkinson's disease. To further elucidate such mechanisms, the ENS constitutes a promising source of material for diagnosis and therapeutic predictions, as it is more accessible than the brain.


Assuntos
Sistema Nervoso Entérico , Doença de Parkinson , Animais , Humanos , Idoso , Sistema Nervoso Entérico/fisiologia , Sistema Nervoso Central , Encéfalo , Envelhecimento
5.
Fungal Genet Biol ; 161: 103711, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35597448

RESUMO

The Crippled Growth (CG) cell degeneration of the model ascomycete Podospora anserina (strain S) is controlled by a prion-like element and has been linked to the self-activation of the PaMpk1 MAP kinase cascade. Here, we report on the identification of the "86-11" locus containing twelve genes, ten of which are involved either in setting up the self-activation loop of CG or in inhibiting this loop, as demonstrated by targeted gene deletion. Interestingly, deletion of the whole locus results only in the elimination of CG and in no detectable additional physiological defect. Sequence comparison shows that these ten genes belong to four different families, each one endowed with a specific activity: two encode factors activating the loop, a third one encodes a factor crucial for inhibition of the loop and the fourth one participates in inhibiting the loop in a pathway parallel to the one controlled by the previously described PDC1 gene. Intriguingly, a very distant homologue of this "86-11" locus is present at the syntenic position in Podospora comata (strain T) that do not present Crippled Growth. Introgression of the P. comata strain T locus in P. anserina strain S and the P. anserina strain S in P. comata strain T showed that both drive CG in the P. anserina strain S genetic background, but not in the genetic background of strain P. comata T, indicating that genetic determinants outside the twelve-gene locus are responsible for lack of CG in P. comata strain T. Our data question the role of this twelve-gene locus in the physiology of P. anserina.


Assuntos
Família Multigênica , Podospora , Deleção de Genes , Sistema de Sinalização das MAP Quinases , Podospora/genética , Podospora/crescimento & desenvolvimento
6.
Arch Virol ; 167(11): 2163-2171, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35840863

RESUMO

Globally, rotavirus C (RVC) causes diarrhoeal outbreaks, mainly in swine, with sporadic incidents in human, bovine, and canine populations. In this study, two human RVC strains, RVC/Human-wt/KOR/CAU13-1-77/2013 and RVC/Human-wt/KOR/CAU14-1-242/2014, were isolated in South Korea, and their complete genome sequences were compared with those of other human- and animal-origin RVC strains found worldwide. Genetic analysis revealed that these viruses have a G4-P[2]-I2-R2-C2-M3-A2-N2-T2-E2-H2 genotype constellation. Phylogenetic analysis indicated that these Korean RVC strains belong to the M3 lineage of the VP3 gene in human RVC from Japan and China and porcine RVC from Japan. These results suggest that RVC circulates in northeast Asia in both the human and porcine populations. These results also provide evidence of interspecies RVC reassortment events.


Assuntos
Infecções por Rotavirus , Rotavirus , Animais , Bovinos , Cães , Genoma Viral , Genótipo , Humanos , Filogenia , Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/veterinária , Suínos
7.
Biophys J ; 120(20): 4325-4336, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34509507

RESUMO

Repeat-induced point mutation is a genetic process that creates cytosine-to-thymine (C-to-T) transitions in duplicated genomic sequences in fungi. Repeat-induced point mutation detects duplications (irrespective of their origin, specific sequence, coding capacity, and genomic positions) by a recombination-independent mechanism that likely matches intact DNA double helices directly, without relying on the annealing of complementary single strands. In the fungus Neurospora crassa, closely positioned repeats can induce mutation of the adjoining nonrepetitive regions. This process is related to heterochromatin assembly and requires the cytosine methyltransferase DIM-2. Using DIM-2-dependent mutation as a readout of homologous pairing, we find that GC-rich repeats produce a much stronger response than AT-rich repeats, independently of their intrinsic propensity to become mutated. We also report that direct repeats trigger much stronger DIM-2-dependent mutation than inverted repeats. These results can be rationalized in the light of a recently proposed model of homologous DNA pairing, in which DNA double helices associate by forming sequence-specific quadruplex-based contacts with a concomitant release of supercoiling. A similar process featuring pairing-induced supercoiling may initiate epigenetic silencing of repetitive DNA in other organisms, including humans.


Assuntos
Citosina , DNA Fúngico , Recombinação Genética , Timina , DNA Fúngico/genética , Mutação , Neurospora crassa/genética
8.
J Exp Bot ; 72(2): 636-653, 2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33529338

RESUMO

Proline (Pro) metabolism plays important roles in protein synthesis, redox balance, and abiotic stress response. However, it is not known if cross-talk occurs between proline and brassinosteroid (BR) signaling pathways. Here, an Arabidopsis intergenic enhancer double mutant, namely proline content alterative 41 (pca41), was generated by inserting a T-DNA tag in the Arabidopsis thaliana ring zinc finger 1 (atrzf1 ) mutant background. pca41 had a T-DNA inserted at the site of the gene encoding BES1/BZR1 Homolog 3 (BEH3). pca41 has a drought-insensitive phenotype that is stronger than atrzf1 under osmotic stress, including high Pro accumulation and decreased amounts of reactive oxygen species. Analysis of physiological, genetic, and molecular networks revealed that negative regulation of BEH3 during abiotic stress was linked to the BR signaling pathway. Our data also suggest that AtRZF1, an E3 ubiquitin ligase, might control osmotic stress, abscisic acid, and BR responses in a BEH3-dependent manner. Under darkness, pca41 displays a long hypocotyl phenotype, which is similar to atrzf1 and beh3, suggesting that BEH3 acts in the same pathway as AtRZF1. Overexpression of BEH3 results in an osmotic stress-sensitive phenotype, which is reversed by exogenous BR application. Taken together, our results indicate that AtRZF1 and BEH3 may play important roles in the osmotic stress response via ubiquitination and BR signaling.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Brassinosteroides , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica de Plantas , Pressão Osmótica , Plantas Geneticamente Modificadas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo
9.
Acta Paediatr ; 110(12): 3261-3268, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34473855

RESUMO

AIM: The aim of this study was to determine clinician opinion regarding oxygen management in moderate-late preterm resuscitation. METHODS: An anonymous online questionnaire was distributed through email/social messaging platforms to neonatologists in 21 countries (October 2020-March 2021) via REDCap. RESULTS: Of the 695 respondents, 69% had access to oxygen blenders and 90% had pulse oximeters. Respondents from high-income countries were more likely to have oxygen blenders than those from middle-income countries (72% vs. 66%). Most initiated respiratory support with FiO2 0.21 (43%) or 0.3 (36%) but only 45% titrated FiO2 to target SpO2 . Most (89%) considered heart rate as a more important indicator of response than SpO2 . Almost all (96%) supported the need for well-designed trials to examine oxygenation in moderate-late preterm resuscitation. CONCLUSION: Most clinicians resuscitated moderate-late preterm infants with lower initial FiO2 but some cannot/will not target SpO2 or titrate FiO2 . Most consider heart rate as a more important indicator of infant response than SpO2 .Large and robust clinical trials examining oxygen use for moderate-late preterm resuscitation, including long-term neurodevelopmental outcomes, are supported amongst clinicians.


Assuntos
Salas de Parto , Oxigênio , Feminino , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Oximetria , Gravidez , Ressuscitação , Inquéritos e Questionários
10.
J Trop Pediatr ; 67(1)2021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33346849

RESUMO

BACKGROUND: Preterm infants in low- and middle-income countries are at high risk of poor physical growth, but their growth data are still scarce. OBJECTIVES: To describe the growth of Vietnamese preterm infants in the first 2 years, and to compare with references: World Health Organization (WHO) child growth standards, and healthy Southeast Asian (SEA) infants. Further, to assess the association between growth in the first year and neurodevelopment at 2 years corrected age (CA). METHODS: We conducted a cohort study to follow up preterm infants discharged from a neonatal intensive care unit for 2 years. Weight, length and head circumference (HC) were measured at 3, 12 and 24 months CA. Neurodevelopment was assessed using Bayley Scales of Infant and Toddler Development-3rd Edition at 24 months CA. RESULTS: Over 90% of the cohort showed catch-up weight at 3 months CA. Weight and length were comparable to healthy SEA but were lower than WHO standards. HC was significantly smaller than those of WHO standards with HC Z-scores steadily decreasing from -0.95 at 3 months CA to -1.50 at 24 months CA. Each one decrement of HC Z-score from 3 to 12 months CA was associated with nearly twice an increase in odds of mental delay at 24 months CA (odds ratio 1.89; 95% confidence interval 1.02-3.50). CONCLUSION: Vietnamese preterm infants exhibited early catch-up weight but poor head growth, which was associated with later delays in mental development. Our findings support the importance of HC measures in follow-up for preterm infants.


Assuntos
Desenvolvimento Infantil , Recém-Nascido Prematuro , Povo Asiático , Estudos de Coortes , Seguimentos , Humanos , Lactente , Recém-Nascido
11.
Fungal Genet Biol ; 136: 103316, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31821884

RESUMO

The development of a tetO/TetR system in the fungus Neurospora crassa is described. The system includes (i) a synthetic gene encoding a TetR variant fused to GFP, and (ii) a standard tetO array integrated homologously, as a proof of principle, near the his-3 gene. The localization of TetR-GFP at the tetO array (observed by fluorescence microscopy) can be disrupted by the application of tetracycline. The full-length array is stable during vegetative growth, but it triggers strong repeat-induced point mutation (RIP) by the RID-dependent as well as the DIM-2-dependent pathways during the sexual phase. Thus, both RIP pathways must be inactivated to allow the faithful inheritance of the unmodified construct. In summary, this study introduces a new molecular tool into Neurospora research, and suggests that the standard tetO array can self-engage in recombination-independent homologous pairing.


Assuntos
Neurospora crassa/genética , Regiões Operadoras Genéticas , Proteínas Repressoras/genética , Tetraciclina/farmacologia , Proteínas de Ligação a DNA/efeitos dos fármacos , Proteínas de Ligação a DNA/genética , Proteínas Fúngicas/efeitos dos fármacos , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Genes Sintéticos , Genoma Fúngico , Recombinação Homóloga , Neurospora crassa/efeitos dos fármacos , Fotomicrografia , Mutação Puntual , Proteínas Recombinantes de Fusão/genética , Sequências Repetitivas de Ácido Nucleico , Proteínas Repressoras/efeitos dos fármacos , Saporinas
12.
Polym Degrad Stab ; 1822020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36936609

RESUMO

The ultraviolet (UV)-induced degradation of graphene/polymer nanocomposites was investigated in this study. Specifically, the effect of few-layer graphene nanofillers on the degradation of a thermoplastic polyurethane (TPU) and the release potential of graphene from the degraded nanocomposite surfaces were assessed. Graphene/TPU (G/TPU) nanocomposites and neat TPU were UV-exposed under both dry and humid conditions in the NIST SPHERE, a precisely controlled, high intensity UV-weathering device. Neat TPU and G/TPU were characterized over the time course of UV exposure using color measurements and infrared spectroscopy, for appearance and chemical changes, respectively. Changes in thickness and surface morphology were obtained with scanning electron microscopy. A new fluorescence quenching measurement approach was developed to identify graphene sheets at the nanocomposite surface, which was supported by contact angle measurements. The potential for graphene release from the nanocomposite surface was evaluated using a tape-lift method followed by microscopy of any particles present on the tape. The findings suggest that graphene improves the service life of TPU with respect to UV exposure, but that graphene becomes exposed at the nanocomposite surface over time, which may potentially lead to its release when exposed to small mechanical forces or upon contact with other materials.

13.
Plant Mol Biol ; 99(4-5): 363-377, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30637572

RESUMO

KEY MESSAGE: Destruction of PAP phosphatase AHL suppresses atrzf1 phenotype in abiotic stress responses. AHL plays an intermediate role in the regulation of proline accumulation by PAP nucleotidase. Proline (Pro) metabolism is important for environmental responses, plant development, and growth. However, the role of Pro in abiotic stress process is unclear. Using atrzf1 (Arabidopsis thaliana ring zinc finger 1) mutant as a parental line for T-DNA tagging mutagenesis, we identified a suppressor mutant designated as proline content alterative 17 (pca17) that suppressed insensitivity of atrzf1 to abiotic stresses during early seedling growth. Pro content of pca17 was lower than that in both wild type (WT) and atrzf1 while complementary lines were less sensitive to abscisic acid (ABA) and abiotic stresses compared to WT. Thermal Asymmetric Interlaced (TAIL)-PCR of pca17 showed that T-DNA was inserted at site of At5g54390 (AHL for Arabidopsis Halotolerance 2-like) encoding 3'-phosphoadenosine-5'-phosphate (PAP) phosphatase. Under drought stress condition, products of sulfate metabolism such as PAP and adenosine monophosphate were significantly lower in pca17 than those in WT and atrzf1. Furthermore, pca17 showed significantly higher levels of several important drought parameters including malondialdehyde, ion leakage, and water loss than WT and atrzf1. Fluorescence signal of green fluorescent protein (GFP)-tagged AHL was quite strong in nuclei of the root and guard cells of transgenic seedlings. Additionally, AHL promoter-ß-glucuronidase (GUS) construct revealed substantial gene expression in vasculature tissues and pollen. Collectively, these findings demonstrate that pca17 acts as a dominant suppressor mutant of atrzf1 in abiotic stress response by modulating proline and sulfate metabolism.


Assuntos
Difosfato de Adenosina/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Ligação a DNA/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Estresse Fisiológico , Ácido Abscísico/farmacologia , Monofosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Secas , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Proteínas de Fluorescência Verde , Peróxido de Hidrogênio/farmacologia , Malondialdeído/metabolismo , Manitol/farmacologia , Mutação , Plantas Geneticamente Modificadas , Prolina/metabolismo , Plântula , Alinhamento de Sequência , Sulfatos/metabolismo
14.
Mol Microbiol ; 110(4): 499-512, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30069939

RESUMO

The model fungus Podospora anserina exhibits Crippled Growth (CG), a cell degeneration process linked to the spreading of a prion-like hereditary element. Previous work has shown that the PaMpk1 MAP kinase and the PaNox1 NADPH oxidase are key player in setting up CG. Here, we identified PDC1, a new gene that negatively regulates the PaMpk1 pathway, by identifying the gene mutated in the PDC2205 mutant. This mutant exhibits strong CG in conditions where the wild-type does not. PDC1 encodes a small protein conserved in other Pezizomycotina. The protein contains four evolutionary-conserved cysteines, a tryptophan and a histidine; all six amino-acid are essential for function. PDC1 is located in the cytosol and is present in lower amounts in stationary hyphae in accordance with its role as a repressor. Epistasis analyses place PDC1 between PaMpk1 and PaNox1.


Assuntos
Proteínas Fúngicas/genética , Proteínas Quinases Ativadas por Mitógeno/genética , NADPH Oxidase 1/genética , Podospora/crescimento & desenvolvimento , Podospora/genética , Piruvato Descarboxilase/genética , Sequência de Aminoácidos/genética , Regulação Fúngica da Expressão Gênica , Hifas/metabolismo , Mutação/genética
15.
Carbon N Y ; 116: 191-200, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28603293

RESUMO

Multiwall carbon nanotubes (MWCNTs) are nanofillers used in consumer and structural polymeric products to enhance a variety of properties. Under weathering, the polymer matrix will degrade and the nanofillers may be released from the products potentially impacting ecological or human health. In this study, we investigated the degradation of a 0.72 % (by mass) MWCNT/amine-cured epoxy nanocomposite irradiated with high intensity ultraviolet (UV) light at various doses, the effects of UV exposure on the surface accumulation and potential release of MWCNTs, and possible mechanisms for the release resistance of the MWCNT surface layer formed on nanocomposites by UV irradiation. Irradiated samples were characterized for chemical degradation, mass loss, surface morphological changes, and MWCNT release using a variety of analytical techniques. Under 295 nm to 400 nm UV radiation up to a dose of 4865 MJ/m2, the nanocomposite matrix underwent photodegradation, resulting in formation of a dense, entangled MWCNT network structure on the surface. However, no MWCNT release was detected, even at very high UV doses, suggesting that the MWCNT surface layer formed from UV irradiation of polymer nanocomposites resist release. Four possible release resistance mechanisms of the UV-induced MWCNT surface layer are presented and discussed.

16.
Artigo em Inglês | MEDLINE | ID: mdl-32855584

RESUMO

The role of the interphase on mechanical performance of glassy polymer/single-walled carbon nanotube composites has been investigated by finite element (FE) method. The matrix and the interphase are modeled using continuum elements and the nanotube is analyzed by Timoshenko beam elements. Stress distribution and mechanical property of the nanocomposites are quantified as a function of the interphase's modulus and thickness. For composites that include an interphase, the predicted moduli are comparable to the values calculated by the rule of mixtures, but are much lower than those of an interphase-free composite. For composites consisting of only the CNT and the matrix, the predicted modulus values are in good agreement with those computed by the rule of mixtures and with theoretical data reported in the literature, although the predicted values are considerably higher than those of real polymer/CNT composites. Using Griffin's fracture analysis for dissimilar materials, we have proved that fracture stress of the weak boundary layer in the CNT/polymer interphase is lower than that of the CNT/polymer interface or of the matrix. The weak boundary layer, which is always existing in a CNT/polymer's three dimensional interphase, is proposed as the main reason for the large discrepancy between Young's moduli predicted by the model observed in this study and reported in the literature and those measured experimentally from real-world polymer/SWCNT composites.

17.
Nanotechnology ; 26(8): 085703, 2015 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-25649345

RESUMO

Despite many studies of subsurface imaging of carbon nanotube (CNT)-polymer composites via scanning electron microscopy (SEM), significant controversy exists concerning the imaging depth and contrast mechanisms. We studied CNT-polyimide composites and, by three-dimensional reconstructions of captured stereo-pair images, determined that the maximum SEM imaging depth was typically hundreds of nanometers. The contrast mechanisms were investigated over a broad range of beam accelerating voltages from 0.3 to 30 kV, and ascribed to modulation by embedded CNTs of the effective secondary electron (SE) emission yield at the polymer surface. This modulation of the SE yield is due to non-uniform surface potential distribution resulting from current flows due to leakage and electron beam induced current. The importance of an external electric field on SEM subsurface imaging was also demonstrated. The insights gained from this study can be generally applied to SEM nondestructive subsurface imaging of conducting nanostructures embedded in dielectric matrices such as graphene-polymer composites, silicon-based single electron transistors, high resolution SEM overlay metrology or e-beam lithography, and have significant implications in nanotechnology.

18.
J Community Health ; 39(1): 23-8, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23877953

RESUMO

Due to the significant rise in pertussis cases reported in 2012, these authors investigated the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine administration at our institution from 2009 to 2012 to determine if changes in prescribing practices reflected published updates from the Advisory Committee on Immunization Practices (ACIP). A single large, urban, private, non-teaching hospital. Documented Tdap vaccines administered from January 2009 through December 2012 were retrieved using an electronic data pull. The incidence of Tdap vaccine administration was reported as number of events per 1,000 patient visits. This data pull served to provide the longitudinal context to prescribing pattern changes at our facility, which were then compared to ACIP vaccination recommendation changes. Tdap administrations increased from 1,365 vaccinations in 2009 to 3,048 vaccinations in 2012. Tdap vaccine administration increased significantly each successive year from 2009 to 2012 from 23.96 ± 1.25 to 47.15 ± 1.63 vaccines per 1,000 patient visits to the facility. Confidence intervals did not overlap for consecutive years representing statistically significant differences between vaccination rates from year to year. Review of Tdap administrations demonstrates a clear and significant increase over consecutive years from 2009 to 2012. Over this time period there were no institutional initiatives aimed at increasing appropriate Tdap use at our institution. This study suggests a correlation between ACIP vaccination recommendations and provider prescribing of Tdap, although no definitive association can be made.


Assuntos
Vacinas contra Difteria, Tétano e Coqueluche Acelular/administração & dosagem , Hospitais Urbanos/estatística & dados numéricos , Guias de Prática Clínica como Assunto , Fidelidade a Diretrizes , Humanos
19.
Pediatr Hematol Oncol ; 31(3): 271-81, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24308730

RESUMO

Hemophagocytic lymphohistiocytosis (HLH) is a rare and fatal hematological syndrome that causes a disturbance of the immune system. Overall mortality of HLH is greater than 50% and the majority of patients who die do so within the first 8 weeks of chemotherapy treatment. To find clinical parameters relating to high-risk HLH patients, this study examined associations between an early fatal outcome and potential prognostic clinical factors and laboratory findings on admission. Eighty-nine pediatric HLH patients were prospectively recruited in Children's Hospital No. 1, Ho-Chi-Minh City, Vietnam, during the period from January 2010 to August 2012. Associations between early fatal outcome and clinical and laboratory findings, including a cerebrospinal fluid examination and virological test on admission, were examined. During the 8-week therapy, 25 (28%) HLH patients died. Persistent fever (>2 weeks), severe thrombocytopenia (<75 × 10(9)/L), hyperbilirubinemia, and prolonged activated partial thromboplastin time (APTT) (>33 sec) were significant risk factors of early fatal outcome. Multivariate logistic regression analysis revealed that thrombocytopenia and prolonged APTT (P for trend was 0.054 and 0.013, respectively) were independently associated with the early fatal outcome. Persistent fever, severe thrombocytopenia, hyperbilirubinemia, and prolonged APTT on admission will be useful and practical predictors to determine high-risk HLH patients.


Assuntos
Linfo-Histiocitose Hemofagocítica/mortalidade , Tempo de Tromboplastina Parcial/mortalidade , Trombocitopenia/mortalidade , Adolescente , Criança , Pré-Escolar , Terapia Combinada , Feminino , Seguimentos , Humanos , Lactente , Linfo-Histiocitose Hemofagocítica/complicações , Linfo-Histiocitose Hemofagocítica/terapia , Masculino , Prognóstico , Estudos Prospectivos , Fatores de Risco , Taxa de Sobrevida , Trombocitopenia/diagnóstico , Trombocitopenia/etiologia , Vietnã/epidemiologia
20.
Cureus ; 16(6): e62317, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38882227

RESUMO

Background The characteristics of amplitude-integrated electroencephalography (aEEG) are associated with neurological outcomes in neonates with hypoxic-ischemic encephalopathy (HIE). We perform a longitudinal analysis of continuous monitoring of aEEG during therapeutic hypothermia and explore the association between aEEG interpretation and clinical neurological outcomes. Method We conducted a prospective cohort study on HIE neonates undergoing hypothermia with aEEG monitoring. Results A total of 37 HIE infants underwent hypothermia with improved aEEG background activity in 28 (75.7%) neonates, of which 18 (48.6%) neonates had background activity returned to a continuous pattern, and the median recovery time was 26.5 hours. Sleep-wake cycle (SWC) appeared in 14 (37.8%) cases, with a median onset time of 34.5 hours. Seizure activity on aEEG was present in 26 (70.3%) infants. Factors associated with poor outcomes at discharge included low voltage or flat trace background activity, a lack of improvement in background activity after hypothermia, and the absence of SWC. Neonates who took longer than 62 hours to return to continuous background activity (time to normal trace) or did not have SWC before the end of hypothermia were more likely to have unfavorable outcomes at discharge. Conclusions Longitudinal analysis of aEEG during hypothermia should be implemented in neonatal care units. The progression of these features on aEEG may predict neurological outcomes for HIE neonates.

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