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1.
Nanotechnology ; 35(23)2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38422541

RESUMO

Structural and electrochemical properties of bismuth ferrite nanostructures produced by pulsed laser deposition with various morphologies are reported. The nanostructures are also explored as electrode materials for high-performance supercapacitors. Scanning electron microscopy images revealed that various bismuth ferrite morphologies were produced by varying the background pressure (10-6, 0.01, 0.10, 0.25, 0.50, 1.0, 2.0 and 4.0 Torr) in the deposition chamber and submitting them to a thermal treatment after deposition at 500◦C. The as-deposited bismuth ferrite nanostructures range from very compact thin-film (10-6, 0.01, 0.10 Torr), to clustered nanoparticles (0.25, 0.50, 1.0 Torr), to very dispersed arrangement of nanoparticles (2.0 and 4.0 Torr). The electrochemical characteristic of the electrodes was investigated through cyclic voltammetry process. The increase in the specific surface area of the nanostructures as background pressure in the chamber increases does not lead to an increase in interfacial capacitance. This is likely due to the wakening of electrical contact between nanoparticles with increasing porosity of the nanostructures. The thermal treatment increased the contact between nanoparticles, which caused an increase in the interfacial capacitance of the nanostructure deposited under high background pressure in the chamber.

2.
Materials (Basel) ; 16(24)2023 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-38138762

RESUMO

Considering the increased anthropogenic emissions of CO2 into the atmosphere, it is important to develop economic incentives for the use of CO2 capture methodologies. The conversion of CO2 into heterocyclic carbonates shows significant potential. However, there is a need for suitable organocatalysts to reach the required efficiency for these reactions. Given this, there has been an increasing focus on the development of organocatalytic systems consisting of a nucleophile and a hydrogen bond donor (HBD) so that CO2 conversion can occur in ambient conditions. In this work, we evaluated the potential of fluorescent carbon dots (CDs) as catalytic HBDs in the ring-opening reaction of epoxides, which is typically the rate-limiting step of CO2 conversion reactions into heterocyclic carbonates. The obtained results demonstrated that the CDs had a relevant catalytic effect on the studied model reaction, with a rate constant of 0.2361 ± 0.008 h-1, a percentage of reactant conversion of 70.8%, and a rate constant enhancement of 32.2%. These results were better than the studied alternative molecular HBDs. Thus, this study demonstrated that CDs have the potential to be used as HBDs and employed in organocatalyzed CO2 conversion into value-added products.

3.
RSC Adv ; 13(41): 28676-28685, 2023 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-37790103

RESUMO

In the present work, Eu2+/Dy3+ ions doped/co-doped into persistent SrAl2O4 microparticles have been developed through solid-state synthesis followed by homogenization and particle size reduction in a ball milling device. These particles have shown a broad and long-persistent afterglow around the 528 nm wavelength of electromagnetic radiation through a broad excitation at around 400 nm. The luminescence intensity was optimized through the selection of different annealing temperatures in the range of 1100 °C to 1500 °C, with intervals of 100 °C. Several structural and optical characterization techniques, such as XRD, SEM, FTIR, thermogravimetric analysis, and photoluminescence, were utilized to judge the preparation and ability of these particles in possible applications in latent fingermark detection on various difficult surfaces. The persistency and stability of these particles were calculated using a digital lux meter.

4.
PLoS One ; 18(3): e0282705, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36893145

RESUMO

Minimizing antibiotic resistance is a key motivation strategy in designing and developing new and combination therapy. In this study, a combination of the antibiotics (cefixime, levofloxacin and gentamicin) with Lysobacter enzymogenes (L. enzymogenes) bioactive proteases present in the cell- free supernatant (CFS) have been investigated against the Gram-positive methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA) and the Gram-negative Escherichia coli (E. coli O157:H7). Results indicated that L. enzymogenes CFS had maximum proteolytic activity after 11 days of incubation and higher growth inhibitory properties against MSSA and MRSA compared to E. coli (O157:H7). The combination of L. enzymogenes CFS with cefixime, gentamicin and levofloxacin at sub-MIC levels, has potentiated their bacterial inhibition capacity. Interestingly, combining cefixime with L. enzymogenes CFS restored its antibacterial activity against MRSA. The MTT assay revealed that L. enzymogenes CFS has no significant reduction in human normal skin fibroblast (CCD-1064SK) cell viability. In conclusion, L. enzymogenes bioactive proteases are natural potentiators for antimicrobials with different bacterial targets including cefixime, gentamicin and levofloxacin representing the beginning of a modern and efficient era in the battle against multidrug-resistant pathogens.


Assuntos
Staphylococcus aureus Resistente à Meticilina , Humanos , Levofloxacino/farmacologia , Peptídeo Hidrolases , Cefixima , Escherichia coli , Virulência , Antibacterianos/farmacologia , Meticilina , Staphylococcus aureus , Gentamicinas/farmacologia , Testes de Sensibilidade Microbiana
5.
Front Vet Sci ; 9: 972057, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36524226

RESUMO

Outcomes research is a relatively recent field of study in animal health and veterinary medicine despite being well-established in human medicine. As the field of animal health is broad-ranging in terms of animal species, objectives, research methodologies, design, analysis, values, and outcomes, there is inherent versatility in the application and impact of the discipline of outcomes research to a variety of stakeholders. The major themes of outcomes relevant to the animal health industry have been distilled down to include, but are not limited to, health, production, economics, and marketing. An outcomes research approach considers an element of value along with an outcome of interest, setting it apart from traditional research approaches. Elements of value are determined by the stakeholders' use of products and/or services that meet or exceed functional, emotional, life-changing, and/or societal needs. Stakeholder perception of value depends on many factors such as the purpose of the animal (e.g., companion vs. food production) and the stakeholder's role (e.g., veterinarian, client, pet-owner, producer, consumer, government official, industry representative, policy holder). Key areas of application of outcomes research principles include comparative medicine, veterinary product development, and post-licensure evaluation of veterinary pharmaceuticals and/or biologics. Topics currently trending in human healthcare outcomes research, such as drug pricing, precision medicine, or the use of real-world evidence, offer novel and interesting perspectives for addressing themes common to the animal health sector. An approach that evaluates the benefits of practices and interventions to veterinary patients and society while maximizing outcomes is paramount to combating many current and future scientific challenges where feeding the world, caring for our aging companion animals, and implementing novel technologies in companion animal medicine and in production animal agriculture are at the forefront of our industry goals.

6.
Anim Health Res Rev ; 23(1): 1-24, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35678500

RESUMO

OBJECTIVE: The objective of this study was to summarize peer-reviewed literature on the prevalence and concentration of non-O157 STEC (O26, O45, O103, O111, O121, and O145) serogroups and virulence genes (stx and eae) in fecal, hide, and carcass samples in pre- and peri-harvest cattle worldwide, using a systematic review of the literature and meta-analyses. DATA SYNTHESIS: Seventy articles were eligible for meta-analysis inclusion; data from 65 articles were subjected to random-effects meta-analysis models to yield fecal prevalence estimates. Meta-regression models were built to explore variables contributing to the between-study heterogeneity. RESULTS: Worldwide pooled non-O157 serogroup, STEC, and EHEC fecal prevalence estimates (95% confidence interval) were 4.7% (3.4-6.3%), 0.7% (0.5-0.8%), and 1.0% (0.8-1.1%), respectively. Fecal prevalence estimates significantly differed by geographic region (P < 0.01) for each outcome classification. Meta-regression analyses identified region, cattle type, and specimen type as factors that contribute to heterogeneity for worldwide fecal prevalence estimates. CONCLUSIONS: The prevalence of these global foodborne pathogens in the cattle reservoir is widespread and highly variable by region. The scarcity of prevalence and concentration data for hide and carcass matrices identifies a large data gap in the literature as these are the closest proxies for potential beef contamination at harvest.


Assuntos
Escherichia coli Shiga Toxigênica , Animais , Bovinos , Fezes , Prevalência , Sorogrupo , Escherichia coli Shiga Toxigênica/genética , Virulência
7.
Arq. Asma, Alerg. Imunol ; 6(2): 285-291, abr.jun.2022. ilus
Artigo em Inglês | LILACS | ID: biblio-1400223

RESUMO

Introduction: The home environment is one of the most favorable spaces for the development of mites because of its low light, humidity, and temperature. Thus, it contributes to the growing cases of allergies among atopic individuals. Objective: To investigate the faunal profile of house dust mites in the city of Rio de Janeiro and the allergenic potential in this region. Methods: Thirty dust samples were collected from homes in the city of Rio de Janeiro, and the species found were classified according to their morphology, family, and genus by classification key. For the collection region, the total protein level was assessed by the Lowry method and electrophoresis under denaturing conditions (SDSPAGE). Results: There was a predominance of Pyroglyphidae mites, accounting for 84.9% of samples; Tyrophagus putrescentiae accounted for 8%, Blomia tropicalis for 6%, Cheyletus malaccensis for 1%, and Acarus siro for 0.1%. The allergen protein content of the samples was the following: group 1 ­ 25 kDa (Der 1, Der p 1, and Blo t 1), group 2 ­ 15 kDa (Der f 2, Der 2, Tyr p 2, and Blo t 2), and group 3 ­ 29-30 kDa (Der f 3 and Blo t 3), which indicates that people in this region are susceptible to sensitization to these mites. Conclusion: Knowledge of the mite fauna in the region under study allows the guidance of health care professionals to perform skin tests for specific mites and conduct treatment according to the pool of mite extracts containing antigens, making immunotherapy more effective.


Introdução: O ambiente domiciliar é um dos espaços favoráveis para o desenvolvimento de ácaros, tendo em vista a baixa luminosidade, umidade e temperatura, o que contribui para os crescentes casos de alergias em indivíduos atópicos. Objetivo: Investigar o perfil faunístico dos ácaros na cidade do Rio de Janeiro e o potencial alergêncio para essa região. Métodos: Foram coletadas 30 amostras de poeira em residências na cidade do Rio de Janeiro, e as espécies encontradas foram classificadas quanto à morfologia, família e o gênero por chave de classificação. Para as regiões das coletas, a carga total de proteínas contendo os alérgenos foi determinada pelo método de Lowry e eletroforese em condições desnaturantes (SDS-PAGE). Resultados: Os resultados mostram a predominância de 84,9% de ácaros da família Pyroglyphidae; para os demais ácaros o percentual corresponde a 8% Tyrophagus putrescentiae, 6% Blomia tropicalis, 1% Cheyletus malaccensis, e 0,1% de Acarus siro. O conteúdo proteico alergêncio constituinte das amostras foram, grupo 1: 25 kDa (Der 1, Der p 1 e Blo t 1); grupo 2: 15 kDa (Der f 2, Der 2, Tyr p 2 e Blo t 2); e para o grupo 3: 29-30 kDa (Der f 3 e Blo t 3), o que indica uma região passível à sensibilização de indivíduos por estes ácaros. Conclusão: O conhecimento da acarofauna nas regiões em estudo permite orientar a comunidade médica quanto à realização de testes cutâneos, além da terapêutica a partir do pool de extratos de ácaros contendo os antígenos, a fim de tornar a imunoterapia mais eficaz.


Assuntos
Humanos , Pyroglyphidae , Poeira , Hipersensibilidade , Ácaros , Terapêutica , Testes Cutâneos , Alérgenos , Características de Residência , Diagnóstico , Ambiente Domiciliar , Umidade , Imunoterapia
8.
Brain Sci ; 11(7)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34356122

RESUMO

Impairments of action semantics (a cognitive domain that critically engages motor brain networks) are pervasive in early Parkinson's disease (PD). However, no study has examined whether action semantic skills in persons with this disease can be influenced by non-invasive neuromodulation. Here, we recruited 22 PD patients and performed a five-day randomized, blinded, sham-controlled study to assess whether anodal transcranial direct current stimulation (atDCS) over the primary motor cortex, combined with cognitive training, can boost action-concept processing. On day 1, participants completed a picture-word association (PWA) task involving action-verb and object-noun conditions. They were then randomly assigned to either an atDCS (n = 11, 2 mA for 20 m) or a sham tDCS (n = 11, 2 mA for 30 s) group and performed an online PWA practice over three days. On day 5, they repeated the initial protocol. Relative to sham tDCS, the atDCS group exhibited faster reaction times for action (as opposed to object) concepts in the post-stimulation test. This result was exclusive to the atDCS group and held irrespective of the subjects' cognitive, executive, and motor skills, further attesting to its specificity. Our findings suggest that action-concept deficits in PD are distinctively grounded in motor networks and might be countered by direct neuromodulation of such circuits. Moreover, they provide new evidence for neurosemantic models and inform a thriving agenda in the embodied cognition framework.

9.
RSC Med Chem ; 12(2): 245-253, 2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-34046613

RESUMO

The human normal breast cell line MCF-10A is being widely used as a model in toxicity studies due to its structural similarity to the normal human mammary epithelium. Over the years, application of carbon dots (C-dots) in biomedicine has been increasing due to their photoluminescence properties, biocompatibility, biosafety and possible applications in bioimaging and as drug carriers. In this work we prepared three different C-dots from the same set of carbon and nitrogen precursors (citric acid and urea, respectively) via three distinct bottom-up synthetic routes and their safety was tested against the normal breast cell line MCF-10A. The characterization results demonstrated a similar size range and composition for all the C-dots. The MCF-10A cells were treated with different concentrations of C-dots for 24, 48 and 72 h to evaluate the cell viability over time. For the 24 h incubation, there were no significant decreases in the viability of the MCF-10A cells. For the 48 h treatment, there was a significant decrease in the viability of the cells treated with calcination-based C-dots, but without significant cellular viability changes for microwave and hydrothermal-based C-dots. For 72 h, cells treated with hydrothermal-based C-dots have the most promising viability profile. Also, compared with paclitaxel, these C-dots have a safety profile very close to that of an antineoplastic in non-tumor cells. Our results suggest that these new C-dots have potential as imaging candidates or biosensing tools as well as drug carriers, and further investigation in animal models is needed for future application in medicine.

10.
Foodborne Pathog Dis ; 18(1): 16-23, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32898446

RESUMO

The objective of this study was to evaluate the effectiveness of a direct-fed microbial (DFM) product in reducing fecal shedding of Escherichia coli O157:H7 in finishing commercial feedlot cattle in Kansas (KS) and Nebraska (NE). Utilizing a randomized complete block design within the feedlot (KS, n = 1; NE, n = 1), cattle were randomly allocated to 20 pens, grouped in blocks of two based on allocation date, and then, within the block, randomly assigned to a treatment group (DFM or negative control). The DFM product was included in the diet at a targeted daily dose of 1 × 109 colony-forming units (CFU) of the Lactobacillus acidophilus and Lactobacillus casei combination per animal for at least 60 d before sampling. Feedlots were sampled for four consecutive weeks; weekly sampling consisted of collecting 20 pen floor fecal samples per pen. Fecal samples were subjected to culture-based methods for detection and isolation of E. coli O157, and positive samples were quantified using real-time polymerase chain reaction. Primary outcomes of interest were fecal prevalence of E. coli O157:H7 and E. coli O157 supershedding (≥104 CFU/g of feces) prevalence. Data for each feedlot were analyzed at the pen level using mixed models accounting for the study design features. Model-adjusted mean E. coli O157:H7 fecal prevalence estimates (standard error of the mean [SEM]) for DFM and control groups were 8.2% (SEM = 2.2%) and 9.9% (SEM = 2.5%) in KS and 14.6% (SEM = 2.8%) versus 14.3% (SEM = 2.6%) in NE; prevalence did not differ significantly between treatment groups at either site (KS, p = 0.51; NE, p = 0.92). Mean E. coli O157 supershedding prevalence estimates for DFM and control groups were 2.2% (SEM = 0.7%) versus 1.8% (SEM = 0.7%) in KS (p = 0.66) and 6.7% (SEM = 1.5%) versus 3.2% (SEM = 1.0%) in NE (p = 0.04). In conclusion, administering the DFM product in the finishing diet of feedlot cattle did not significantly reduce E. coli O157:H7 fecal prevalence or supershedding prevalence in study pens at either commercial feedlot.


Assuntos
Doenças dos Bovinos/prevenção & controle , Infecções por Escherichia coli/prevenção & controle , Escherichia coli O157 , Lacticaseibacillus casei , Lactobacillus acidophilus , Probióticos/administração & dosagem , Ração Animal/microbiologia , Animais , Derrame de Bactérias , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/microbiologia , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Fezes/microbiologia , Kansas/epidemiologia , Nebraska/epidemiologia
11.
Front Neurol ; 11: 597955, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33329353

RESUMO

Cognitive deficits are increasingly being recognized as a common trait in Parkinson's disease (PD). Recently, transcranial direct current stimulation (tDCS) has been shown to exert positive effects as an adjunctive therapy on motor and non-motor symptoms in PD. This systematic review and meta-analysis aims to provide an overview of reported evidence on the efficacy of tDCS interventions in the treatment of cognitive impairments in PD. A systematic literature review was conducted to examine articles that were published in the past 10 years and that study the effects of tDCS on cognitive deficits in PD patients. The PubMed, Scopus and Scielo databases were searched. Eight tDCS studies involving 168 participants were included for the analysis. Our meta-analysis results showed that anodal tDCS (atDCS) had various levels or no evidence of effectiveness. In the pre-post stimulation analysis, a strong effect was reported for executive functions (pre-post: g = 1.51, Z = 2.41, p = 0.016); non-significant effects were reported for visuospatial skills (pre-post: g = 0.27, Z = 0.69, p = 0.490); attention (pre-post: g = 0.02, Z = 0.08, p = 0.934), memory (pre-post: g = 0.01, Z = 0.03, p = 0.972) and language (pre-post: g = 0.07, Z = 0.21, p = 0.832). However, in the pre-follow-up stimulation analysis, the duration of the effect was not clear. This study highlights the potential effectiveness of atDCS to improve cognitive performance in PD patients but failed to establish a cause-effect relationship between tDCS intervention and cognitive improvement in PD. Future directions and recommendations for methodological improvements are outlined.

12.
Inorg Chem ; 59(18): 12983-12987, 2020 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-32897061

RESUMO

Two air-stable, isostructural, mononuclear six-coordinate manganese(II) and cobalt(II) oxamate complexes, [M(4-HOpa)2(H2O)2] [4-HOpa = N-4-hydroxyphenyloxamate; M= Mn2+ (1) or Co2+ (2)], exhibit field-induced slow magnetic relaxation. A bottleneck process is observed throughout the temperature range of 2-20 K for 1, while for 2, it dominates only at low temperatures (2-4 K). Additionally, the Raman process [n = 6.9(2)] is responsible for an increase in the relaxation time at higher temperatures to 2.

13.
Nanomaterials (Basel) ; 10(7)2020 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-32635483

RESUMO

Carbon dots (CDs) are carbon-based nanoparticles with very attractive luminescence features. Furthermore, their synthesis by bottom-up strategies is quite flexible, as tuning the reaction precursors and synthesis procedures can lead to an endless number of CDs with distinct properties and applications. However, this complex variability has made the characterization of the structural and optical properties of the nanomaterials difficult. Herein, we performed a systematic evaluation of the effect of three representative bottom-up strategies (hydrothermal, microwave-assisted, and calcination) on the properties of CDs prepared from the same precursors (citric acid and urea). Our results revealed that these synthesis routes led to nanoparticles with similar sizes, identical excitation-dependent blue-to-green emission, and similar surface-functionalization. However, we have also found that microwave and calcination strategies are more efficient towards nitrogen-doping than hydrothermal synthesis, and thus, the former routes are able to generate CDs with significantly higher fluorescence quantum yields than the latter. Furthermore, the different synthesis strategies appear to have a role in the origin of the photoluminescence of the CDs, as hydrothermal-based nanoparticles present an emission more dependent on surface states, while microwave- and calcination-based CDs present an emission with more contributions from core states. Furthermore, calcination and microwave routes are more suitable for high-yield synthesis (~27-29%), while hydrothermal synthesis present almost negligible synthesis yields (~2%). Finally, life cycle assessment (LCA) was performed to investigate the sustainability of these processes and indicated microwave synthesis as the best choice for future studies.

14.
Nanomaterials (Basel) ; 10(6)2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32575837

RESUMO

Spent coffee grounds (SCGs) are known for containing many organic compounds of interest, including carbohydrates, lipids, phenolic compounds and proteins. Therefore, we investigated them as a potential source to obtain carbon dots (CDs) via a nanotechnology approach. Herein, a comparison was performed between CDs produced by SCGs and classic precursors (e.g., citric acid and urea). The SCG-based CDs were obtained via the one-pot and solvent-free carbonization of solid samples, generating nanosized particles (2.1-3.9 nm). These nanoparticles exhibited a blue fluorescence with moderate quantum yields (2.9-5.8%) and an excitation-dependent emission characteristic of carbon dots. SCG-based CDs showed potential as environmentally relevant fluorescent probes for Fe3+ in water. More importantly, life cycle assessment studies validated the production of CDs from SCG samples as a more environmentally sustainable route, as compared to those using classic reported precursors, when considering either a weight- or a function-based functional unit.

15.
BMC Vet Res ; 15(1): 394, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31690309

RESUMO

BACKGROUND: Osteoarthritis (OA) affects nearly 20% of all dogs greater than one year of age. Clinical signs include pain, discomfort, lameness, and ultimately lead to disability. Although there is currently no known cure, there are many therapeutic options that can slow the progression and alleviate the associated signs. There is ample supportive evidence demonstrating the efficaciousness of carprofen, a non-steroidal anti-inflammatory drug, in managing signs of OA. Since the approval of the pioneer product (Rimadyl®, Zoetis; Kalamazoo, Michigan), the United States Food and Drug Administration (FDA) has assented to several other generic, bioequivalent products. The objective of this 2 × 2 complete cross-over design was to assess the acceptance of two bioequivalent carprofen liver-flavored chewable tablets (containing 25 mg carprofen), Rimadyl® and Carprieve® (Norbrook Laboratories Limited; Newry, Northern Ireland) in 37 healthy purpose-bred dogs. RESULTS: Overall, 73.0% (27/37) and 70.3% (26/37) of dogs voluntarily accepted Rimadyl® and Carprieve®, respectively. Considering acceptability tests paired by individual dog, 64.9% of dogs (n = 24) voluntarily accepted both Rimadyl® and Carprieve® chewable tablets whereas 21.6% (8) of dogs denied or partially accepted both products offered. Three dogs (8.1%) fully accepted Rimadyl® but did not accept Carprieve®. Conversely, two dogs (5.4%) fully accepted Carprieve® but did not accept Rimadyl®. Canine acceptability did not significantly differ between Carprieve® and Rimadyl® carprofen chewable tablets (P = 0.65). CONCLUSIONS: Utilizing a 2 × 2 complete cross-over design, this study provides evidence that canine acceptability of a single-dose did not differ between Carprieve® and Rimadyl® chewable tablets.


Assuntos
Anti-Inflamatórios não Esteroides/administração & dosagem , Carbazóis/administração & dosagem , Cães , Animais , Estudos Cross-Over , Feminino , Masculino , Comprimidos , Paladar
16.
Science ; 366(6462): 250-254, 2019 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-31601771

RESUMO

The unconventional N-methyl-d-aspartate (NMDA) receptor subunits GluN3A and GluN3B can, when associated with the other glycine-binding subunit GluN1, generate excitatory conductances purely activated by glycine. However, functional GluN1/GluN3 receptors have not been identified in native adult tissues. We discovered that GluN1/GluN3A receptors are operational in neurons of the mouse adult medial habenula (MHb), an epithalamic area controlling aversive physiological states. In the absence of glycinergic neuronal specializations in the MHb, glial cells tuned neuronal activity via GluN1/GluN3A receptors. Reducing GluN1/GluN3A receptor levels in the MHb prevented place-aversion conditioning. Our study extends the physiological and behavioral implications of glycine by demonstrating its control of negatively valued emotional associations via excitatory glycinergic NMDA receptors.


Assuntos
Comportamento Animal , Emoções , Glicina/metabolismo , Habenula/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Animais , Cálcio/metabolismo , Linhagem Celular , Condicionamento Psicológico , Sinais (Psicologia) , Glicina/farmacologia , Humanos , Camundongos , Camundongos Knockout , Neuroglia/metabolismo , Neurônios/metabolismo , Técnicas de Patch-Clamp
17.
Phys Chem Chem Phys ; 21(37): 20919-20926, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31517344

RESUMO

Carbon dots have attracted great attention from the research community given their very attractive luminescent properties. However, the recent discovery that some of these properties may result from fluorescent impurities originating from the synthesis process, and not from the carbon dots themselves, constitute a significant setback to our knowledge of these materials. Herein, we proceeded to the study of carbon dots generated from citric acid and urea via a microwave-assisted synthesis, focusing on their analysis by AFM, HR-TEM, XPS, FT-IR, ESI-MS, UV-Vis and fluorescence spectroscopy. We have found that this synthesis process does generate molecular fluorophores that can mask the luminescence of the carbon dots. More importantly, our data demonstrates that when present in the same solution, the carbon dots and these fluorophores do not behave as separated species with individual emission. Instead, they interact to produce a hybrid luminescence, which excited state properties and reactivity are different from the properties of the individual species. These results indicate the possibility for the development of hybrid materials composed by carbon dots and related molecular fluorophores with new and improved properties.

18.
Crit Rev Anal Chem ; 49(6): 542-552, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30739473

RESUMO

Diabetes mellitus is a chronic disease and leading cause of death worldwide, affecting more than 420 million people. High blood glucose levels are a common effect of uncontrolled diabetes, which can cause serious health damage. Diabetic individuals must measure their blood glucose levels regularly in order to control glycemic levels and minimize the effects of the disease. Glucose sensors have been used in the management of diabetes for more than 50 years, when Clark and Ann Lyons developed the first glucose enzyme electrode in 1962. Electrochemical sensors have become the leading technology for glucose concentration measuring with most of the commercially available devices being based on amperometric detection. However, the detection of glucose in the blood is still an object of intense research. The development of new fluorescent nanomaterials begins to constitute an alternative for glucose blood quantification. These sensors include carbon dots, quantum dots, graphene quantum dots, gold, silver and upconversion nanoparticles. This paper reviews the last 10 year fluorescent nanoparticles based technologies proposed for glucose monitoring and provide an insight into emerging optical fluorescence glucose biosensors.


Assuntos
Glicemia/análise , Nanopartículas Metálicas/química , Carbono/química , Corantes Fluorescentes , Humanos , Pontos Quânticos , Espectrometria de Fluorescência
19.
J Fluoresc ; 29(1): 265-270, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30612287

RESUMO

The selective fluorescence sensing of fructose was achieved by fluorescence quenching of the emission of hydrothermal-synthesized carbon quantum dots prepared by 3-hydroxyphenylboronic acid. Quantification of fructose was possible in aqueous solutions with pH of 9 (Limit of Detection LOD and Limit of Quantification LOQ of 2.04 and 6.12 mM), by quenching of the emission at 376 nm and excitation ~380 nm with a linearity range of 0-150 mM. A Stern-Volmer constant (KSV) of 2.11 × 10-2 mM-1 was obtained, while a fluorescent quantum yield of 31% was calculated. The sensitivity of this assay towards fructose was confirmed by comparison with other sugars (such as glucose, sucrose and lactose). Finally, the validity of the proposed assays was further demonstrated by performing recovery assays in different matrixes. Graphical Abstract.

20.
Neuroimage Clin ; 18: 543-552, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29845003

RESUMO

The frontal lobes are one of the most complex brain structures involved in both domain-general and specific functions. The goal of this work was to assess the anatomical and cognitive affectations from a unique case with massive bilateral frontal affectation. We report the case of GC, an eight-year old child with nearly complete affectation of bilateral frontal structures and spared temporal, parietal, occipital, and cerebellar regions. We performed behavioral, neuropsychological, and imaging (MRI, DTI, fMRI) evaluations. Neurological and neuropsychological examinations revealed a mixed pattern of affected (executive control/abstraction capacity) and considerably preserved (consciousness, language, memory, spatial orientation, and socio-emotional) functions. Both structural (DTI) and functional (fMRI) connectivity evidenced abnormal anterior connections of the amygdala and parietal networks. In addition, brain structural connectivity analysis revealed almost complete loss of frontal connections, with atypical temporo-posterior pathways. Similarly, functional connectivity showed an aberrant frontoparietal network and relative preservation of the posterior part of the default mode network and the visual network. We discuss this multilevel pattern of behavioral, structural, and functional connectivity results. With its unique pattern of compromised and preserved structures and functions, this exceptional case offers new constraints and challenges for neurocognitive theories.


Assuntos
Cognição/fisiologia , Função Executiva/fisiologia , Lobo Frontal/anormalidades , Lobo Frontal/diagnóstico por imagem , Rede Nervosa/diagnóstico por imagem , Criança , Imagem de Tensor de Difusão , Feminino , Lobo Frontal/fisiopatologia , Humanos , Idioma , Imageamento por Ressonância Magnética , Memória/fisiologia , Rede Nervosa/fisiopatologia , Testes Neuropsicológicos
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