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1.
Cytotherapy ; 26(7): 700-713, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38483360

RESUMO

BACKGROUND AIMS: Parkinson's disease (PD) is the second most common neurodegenerative disorder. The etiology of the disease remains largely unknown, but evidence have suggested that the overexpression and aggregation of alpha-synuclein (α-syn) play key roles in the pathogenesis and progression of PD. Mesenchymal stromal cells (MSCs) have been earning attention in this field, mainly due to their paracrine capacity. The bioactive molecules secreted by MSCs, i.e. their secretome, have been associated with enhanced neuronal survival as well as a strong modulatory capacity of the microenvironments where the disease develops. The selection of the appropriate animal model is crucial in studies of efficacy assessment. Given the involvement of α-syn in the pathogenesis of PD, the evidence generated from the use of animal models that develop a pathologic phenotype due to the action of this protein is extremely valuable. Therefore, in this work, we established an animal model based on the viral vector-mediated overexpression of A53T α-syn and studied the impact of the secretome of bone marrow mesenchymal stromal cells MSC(M) as a therapeutic strategy. METHODS: Adult male rats were subjected to α-syn over expression in the nigrostriatal pathway to model dopaminergic neurodegeneration. The impact of locally administered secretome treatment from MSC(M) was studied. Motor impairments were assessed throughout the study coupled with whole-region (striatum and substantia nigra) confocal microscopy evaluation of histopathological changes associated with dopaminergic neurodegeneration and glial cell reactivity. RESULTS: Ten weeks after lesion induction, the animals received secretome injections in the substantia nigra pars compacta (SNpc) and striatum (STR). The secretome used was produced from bone marrow mesenchymal stromal cells MSC(M) expanded in a spinner flask (SP) system. Nine weeks later, animals that received the viral vector containing the gene for A53T α-syn and treated with vehicle (Neurobasal-A medium) presented dopaminergic cell loss in the SNpc and denervation in the STR. The treatment with secretome significantly reduced the levels of α-syn in the SNpc and protected the dopaminergic neurons (DAn) within the SNpc and STR. CONCLUSIONS: Our results are aligned with previous studies in both α-syn Caenorhabditis elegans models, as well as 6-OHDA rodent model, revealing that secretome exerted a neuroprotective effect. Moreover, these effects were associated with a modulation of microglial reactivity supporting an immunomodulatory role for the factors contained within the secretome. This further supports the development of new studies exploring the effects and the mechanism of action of secretome from MSC(M) against α-syn-induced neurotoxicity.


Assuntos
Modelos Animais de Doenças , Células-Tronco Mesenquimais , Microglia , Neuroproteção , Doença de Parkinson , alfa-Sinucleína , Animais , Células-Tronco Mesenquimais/metabolismo , alfa-Sinucleína/metabolismo , alfa-Sinucleína/genética , Ratos , Masculino , Microglia/metabolismo , Doença de Parkinson/terapia , Doença de Parkinson/metabolismo , Secretoma/metabolismo , Neurônios Dopaminérgicos/metabolismo , Transplante de Células-Tronco Mesenquimais/métodos , Células Cultivadas , Humanos
2.
J Oral Rehabil ; 51(7): 1213-1220, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38606658

RESUMO

OBJECTIVE: The Ecological Momentary Assessment (EMA) concept was the basis for developing a smartphone application for the real-time report of awake bruxism (AB) activities. The aim of this study was to assess the effects of the EMA with a randomised controlled trial designed to compare the frequency of AB reported in two separate single observation points between a group of students monitored over time with an EMA smartphone application and a non-EMA monitored group. METHODS: Sixty-four (N = 64) dental students (22.3 YO [±2.6]; 52F; 12 M) answered the Oral Behaviour Checklist (OBC-1) and were randomised into an EMA-group (EG) and control group (CG). EG were monitored with a smartphone application for AB report during seven consecutive days and completed three EMA monitoring periods (EMA-1, 2 and 3) at one-month intervals. After the third period (EMA-3), both EG and CG answered again the OBC (OBC-2). Descriptive statistics were performed to characterise the sample. Pearson's chi-squared test, Fixer Exact test and post hoc Z test with Bonferroni correction were performed. The study hypothesis was that EMA could influence the AB reported by the participants because it implies an increase in the awareness, self-recognition, and self-control of bruxism behaviours. The level of significance was set at p < .05. RESULT: The percentage of participants who changed the report of the activity of clenching their teeth while awake between OBC-1 and OBC-2 was significantly higher among participants in EG, when compared to CG (p = .027). For all other behaviours reported the within- and between-group differences from OBC-1 to OBC-2 were not significant. Clenching and bracing were the most frequently reported, whilst grinding was the less frequent behaviour. CONCLUSION: A smartphone-based EMA approach demonstrated be useful to monitor AB over time, increasing individual's awareness, particularly to bracing and clenching behaviours.


Assuntos
Bruxismo , Avaliação Momentânea Ecológica , Aplicativos Móveis , Smartphone , Estudantes de Odontologia , Humanos , Masculino , Feminino , Estudantes de Odontologia/psicologia , Adulto Jovem , Vigília/fisiologia , Adulto
3.
Sensors (Basel) ; 23(4)2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36850801

RESUMO

The ocean has a huge impact on our way of life; therefore, there is a need to monitor and protect its biodiversity [...].


Assuntos
Biodiversidade , Oceanos e Mares
4.
Biomed Microdevices ; 24(2): 20, 2022 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-35670892

RESUMO

The efficient separation of blood components using microfluidic systems can help to improve the detection and diagnosis of several diseases, such as malaria and diabetes. Therefore, a novel multi-step microfluidic device, based on passive crossflow filters was developed. Three different designs were proposed, fabricated and tested in order to evaluate the most suitable geometry to perform, simultaneously, blood cells separation and cell deformability measurements. All the proposed geometries include a main channel and three sequential separation steps, all comprised of symmetrical crossflow filters, with multiple rows of pillars, to reduce the amount of red blood cells (RBCs) flowing to the outlets of the microfluidic device (MD). Sets of hyperbolic constrictions located at the outlets allow the assessment of cells deformability. Based on the proposed geometries, the three correspondent MD were evaluated and compared, by measuring the RBCs velocities, the cell-free layer (CFL) effect through the microchannels and by quantifying the amount of RBCs at the outlets. The results suggest that the proposed MD 3 configuration was the most effective one for the desired application, due to the formation of a wider CFL. As a result, a minor amount of RBCs flow through the hyperbolic contraction at the third separation level of the device. Nevertheless, for all the proposed geometries, the existence of three separation levels shows that it is possible to achieve a highly efficient cell separation. If needed, such microdevices have the potential for further improvements by increasing the number of separation levels, aiming the total separation of blood cells from plasma.


Assuntos
Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas , Separação Celular , Contagem de Eritrócitos , Deformação Eritrocítica , Eritrócitos
5.
Sensors (Basel) ; 22(4)2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-35214242

RESUMO

A linear electromagnetic energy harvesting device for underwater applications, fabricated with a simple manufacturing process, was developed to operate with movement frequencies from 0.1 to 0.4 Hz. The generator has two coils, and the effect of the combination of the two coils was investigated. The experimental study has shown that the energy capture system was able to supply energy to several ocean sensors, producing 7.77 mJ per second with wave movements at 0.4 Hz. This study shows that this energy is enough to restore the energy used by the battery or the capacitor and continue supplying energy to the sensors used in the experimental work. For an ocean wave frequency of 0.4 Hz, the generator can supply power to 8 sensors or 48 sensors, depending on the energy consumed and its optimization.


Assuntos
Fontes de Energia Elétrica , Movimento , Fenômenos Físicos
6.
Int J Mol Sci ; 23(22)2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36430308

RESUMO

Spinal cord injury (SCI) is a disabling condition that disrupts motor, sensory, and autonomic functions. Despite extensive research in the last decades, SCI continues to be a global health priority affecting thousands of individuals every year. The lack of effective therapeutic strategies for patients with SCI reflects its complex pathophysiology that leads to the point of no return in its function repair and regeneration capacity. Recently, however, several studies started to uncover the intricate network of mechanisms involved in SCI leading to the development of new therapeutic approaches. In this work, we present a detailed description of the physiology and anatomy of the spinal cord and the pathophysiology of SCI. Additionally, we provide an overview of different molecular strategies that demonstrate promising potential in the modulation of the secondary injury events that promote neuroprotection or neuroregeneration. We also briefly discuss other emerging therapies, including cell-based therapies, biomaterials, and epidural electric stimulation. A successful therapy might target different pathologic events to control the progression of secondary damage of SCI and promote regeneration leading to functional recovery.


Assuntos
Traumatismos da Medula Espinal , Humanos , Regeneração Nervosa/fisiologia , Recuperação de Função Fisiológica/fisiologia , Neuroproteção
7.
Sensors (Basel) ; 21(9)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-34068811

RESUMO

Three-dimensional (3D) in vitro models, such as organ-on-a-chip platforms, are an emerging and effective technology that allows the replication of the function of tissues and organs, bridging the gap amid the conventional models based on planar cell cultures or animals and the complex human system. Hence, they have been increasingly used for biomedical research, such as drug discovery and personalized healthcare. A promising strategy for their fabrication is 3D printing, a layer-by-layer fabrication process that allows the construction of complex 3D structures. In contrast, 3D bioprinting, an evolving biofabrication method, focuses on the accurate deposition of hydrogel bioinks loaded with cells to construct tissue-engineered structures. The purpose of the present work is to conduct a systematic review (SR) of the published literature, according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, providing a source of information on the evolution of organ-on-a-chip platforms obtained resorting to 3D printing and bioprinting techniques. In the literature search, PubMed, Scopus, and ScienceDirect databases were used, and two authors independently performed the search, study selection, and data extraction. The goal of this SR is to highlight the importance and advantages of using 3D printing techniques in obtaining organ-on-a-chip platforms, and also to identify potential gaps and future perspectives in this research field. Additionally, challenges in integrating sensors in organs-on-chip platforms are briefly investigated and discussed.


Assuntos
Bioimpressão , Dispositivos Lab-On-A-Chip , Animais , Humanos , Hidrogéis , Impressão Tridimensional , Engenharia Tecidual
8.
J Neuroinflammation ; 17(1): 282, 2020 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-32967684

RESUMO

BACKGROUND: Alterations in the immune system are a complication of spinal cord injury (SCI) and have been linked to an excessive sympathetic outflow to lymphoid organs. Still unknown is whether these peripheral immune changes also contribute for the deleterious inflammatory response mounted at the injured spinal cord. METHODS: We analyzed different molecular outputs of the splenic sympathetic signaling for the first 24 h after a thoracic compression SCI. We also analyzed the effect of ablating the splenic sympathetic signaling to the innate immune and inflammatory response at the spleen and spinal cord 24 h after injury. RESULTS: We found that norepinephrine (NE) levels were already raised at this time-point. Low doses of NE stimulation of splenocytes in vitro mainly affected the neutrophils' population promoting an increase in both frequency and numbers. Interestingly, the interruption of the sympathetic communication to the spleen, by ablating the splenic nerve, resulted in reduced frequencies and numbers of neutrophils both at the spleen and spinal cord 1 day post-injury. CONCLUSION: Collectively, our data demonstrates that the splenic sympathetic signaling is involved in the infiltration of neutrophils after spinal cord injury. Our findings give new mechanistic insights into the dysfunctional regulation of the inflammatory response mounted at the injured spinal cord.


Assuntos
Fibras Adrenérgicas/fisiologia , Infiltração de Neutrófilos/fisiologia , Transdução de Sinais/fisiologia , Traumatismos da Medula Espinal/fisiopatologia , Baço/inervação , Baço/fisiologia , Fibras Adrenérgicas/química , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Traumatismos da Medula Espinal/imunologia , Vértebras Torácicas
9.
Small ; 16(51): e2003517, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33236819

RESUMO

Despite the progress achieved in nanomedicine during the last decade, the translation of new nanotechnology-based therapeutic systems into clinical applications has been slow, especially due to the lack of robust preclinical tissue culture platforms able to mimic the in vivo conditions found in the human body and to predict the performance and biotoxicity of the developed nanomaterials. Organ-on-a-chip (OoC) platforms are novel microfluidic tools that mimic complex human organ functions at the microscale level. These integrated microfluidic networks, with 3D tissue engineered models, have been shown high potential to reduce the discrepancies between the results derived from preclinical and clinical trials. However, there are many challenges that still need to be addressed, such as the integration of biosensor modules for long-time monitoring of different physicochemical and biochemical parameters. In this review, recent advances on OoC platforms, particularly on the preclinical validation of nanomaterials designed for cancer, as well as the current challenges and possible future directions for an end-use perspective are discussed.


Assuntos
Microfluídica , Nanomedicina , Humanos , Dispositivos Lab-On-A-Chip , Análise de Sequência com Séries de Oligonucleotídeos , Engenharia Tecidual
10.
Am Heart J ; 226: 114-126, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32531501

RESUMO

BACKGROUND: Fabry disease (FD) is a treatable cause of hypertrophic cardiomyopathy (HCM). We aimed to determine the independent predictors of FD and to define a clinically useful strategy to discriminate FD among HCM. METHODS: Multicenter study including 780 patients with the ESC definition of HCM. FD screening was performed by enzymatic assay in males and genetic testing in females. Multivariate regression analysis identified independent predictors of FD in HCM. A discriminant function analysis defined a score based on the weighted combination of these predictors. RESULTS: FD was found in 37 of 780 patients with HCM (4.7%): 31 with p.F113L mutation due to a founder effect; and 6 with other variants (p.C94S; p.M96V; p.G183V; p.E203X; p.M290I; p.R356Q/p.G360R). FD prevalence in HCM adjusted for the founder effect was 0.9%. Symmetric HCM (OR 3.464, CI95% 1.151-10.430), basal inferolateral late gadolinium enhancement (LGE) (OR 10.677, CI95% 3.633-31.380), bifascicular block (OR 10.909, CI95% 2.377-50.059) and ST-segment depression (OR 4.401, CI95% 1.431-13.533) were independent predictors of FD in HCM. The score ID FABRY-HCM [-0.729 + (2.781xBifascicular block) + (0.590xST depression) + (0.831xSymmetric HCM) + (2.130xbasal inferolateral LGE)] had a negative predictive value of 95.8% for FD, with a cut-off of 1.0, meaning that, in the absence of both bifascicular block and basal inferolateral LGE, FD is a less probable cause of HCM, being more appropriate to perform HCM gene panel than targeted FD screening. CONCLUSION: FD prevalence in HCM was 0.9%. Bifascicular block and basal inferolateral LGE were the most powerful predictors of FD in HCM. In their absence, HCM gene panel is the most appropriate step in etiological study of HCM.


Assuntos
Cardiomiopatia Hipertrófica/etiologia , Doença de Fabry/complicações , Doença de Fabry/diagnóstico , Adulto , Idoso , Doença de Fabry/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem
11.
Int J Mol Sci ; 21(14)2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32709070

RESUMO

Citalopram is a selective serotonin reuptake inhibitor, and although widely used as an antidepressant, this drug has also demonstrated interesting repairing properties leading to motor recovery and pathology amelioration in animal models of stroke and degeneration. Here, we tested the efficacy of both 7-day and 8-week citalopram treatment in a contusive spinal cord injury (SCI) rat model. A combination of behavioral tests, histological and serum cytokine analysis was used to assess overall recovery. Despite promoting a mild reduction of inflammatory cells as well as an early, but transient increase of specific serum cytokines, citalopram administration showed no overall beneficial effects on motor performance or lesion extension. Our results do not support citalopram treatment as a therapeutic strategy for SCI.


Assuntos
Citalopram/uso terapêutico , Inibidores Seletivos de Recaptação de Serotonina/uso terapêutico , Traumatismos da Medula Espinal/tratamento farmacológico , Animais , Citalopram/administração & dosagem , Modelos Animais de Doenças , Feminino , Ratos , Ratos Wistar , Recuperação de Função Fisiológica/efeitos dos fármacos , Inibidores Seletivos de Recaptação de Serotonina/administração & dosagem , Medula Espinal/efeitos dos fármacos , Medula Espinal/patologia , Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/patologia , Traumatismos da Medula Espinal/fisiopatologia , Resultado do Tratamento
12.
Health Res Policy Syst ; 16(1): 102, 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30376876

RESUMO

OBJECTIVE: To describe the implementation, main intervention areas and initial results of the Integrated Strategy for the Promotion of Healthy Eating (EIPAS) in Portugal. METHODS: EIPAS was published as a Law, in December of 2017, as a result of a collaboration between several ministries, including the Finance, Internal Affairs, Education, Health, Economy, Agriculture, and Sea Ministries, aiming at improving the dietary habits of the Portuguese population. The working group, led by the Ministry of Health, developed this strategy for over a year. The framework produced was based on WHO and European Commission recommendations as well as on relevant data from the last Portuguese dietary intake survey (2015/2016). EIPAS also reflects the results of a public hearing, including the food industry, among others, and the experience gathered, since 2012, through the National Programme for the Promotion of Healthy Eating. It considers the 'health in all policies' challenge set by WHO and has four different strategic areas, namely (1) creation of healthier food environments, (2) improvement of the quality and accessibility of healthy food choices for consumers, (3) promotion and development of literacy, in order to encourage healthy food choices, and (4) promotion of innovation and entrepreneurship. In order to achieve these goals, a set of 51 actions was established and assigned to the seven ministries involved. RESULTS: Under the scope of this strategy, Portugal has already implemented several actions, including (1) definition of standards for food availability at all public healthcare institutions; (2) implementation of a sugar tax on sweetened beverages; (3) implementation of a voluntary agreement with the food industry sector for food reformulation (work in progress); (4) design of a proposal for an interpretative model of front-of-pack food labelling; (5) improvement of the nutritional quality of food aid programmes for low-income groups; and (6) regulation of marketing of unhealthy foods to children. CONCLUSIONS: For the first time, Portugal has a nutrition policy based on the WHO concept of 'health in all policies' and on the national data on food intake. The implementing process of all 51 actions and the inherent complexities and difficulties found so far have made this process be an authentic political and social laboratory that deserves to be followed.


Assuntos
Dieta Saudável , Comportamento Alimentar , Órgãos Governamentais , Promoção da Saúde/métodos , Política Nutricional , Adulto , Bebidas , Criança , Açúcares da Dieta , Assistência Alimentar , Indústria Alimentícia , Rotulagem de Alimentos , Regulamentação Governamental , Humanos , Marketing , Valor Nutritivo , Saúde Pública , Impostos
13.
Biomed Microdevices ; 19(1): 6, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28092011

RESUMO

Gas embolisms can hinder blood flow and lead to occlusion of the vessels and ischemia. Bubbles in microvessels circulate as tubular bubbles (Taylor bubbles) and can be trapped, blocking the normal flow of blood. To understand how Taylor bubbles flow in microcirculation, in particular, how bubbles disturb the blood flow at the scale of blood cells, experiments were performed in microchannels at a low Capillary number. Bubbles moving with a stream of in vitro blood were filmed with the help of a high-speed camera. Cell-free layers (CFLs) were observed downstream of the bubble, near the microchannel walls and along the centerline, and their thicknesses were quantified. Upstream to the bubble, the cell concentration is higher and CFLs are less clear. While just upstream of the bubble the maximum RBC concentration happens at positions closest to the wall, downstream the maximum is in an intermediate region between the centerline and the wall. Bubbles within microchannels promote complex spatio-temporal variations of the CFL thickness along the microchannel with significant relevance for local rheology and transport processes. The phenomenon is explained by the flow pattern characteristic of low Capillary number flows. Spatio-temporal variations of blood rheology may have an important role in bubble trapping and dislodging.


Assuntos
Dispositivos Lab-On-A-Chip , Microbolhas , Reologia
14.
Proc Natl Acad Sci U S A ; 111(14): 5183-8, 2014 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-24706863

RESUMO

Symbiosis between rhizobia soil bacteria and legume plants results in the formation of root nodules where plant cells are fully packed with nitrogen fixing bacteria. In the host cells, the bacteria adapt to the intracellular environment and gain the ability for nitrogen fixation. Depending on the host plants, the symbiotic fate of bacteria can be either reversible or irreversible. In Medicago and related legume species, the bacteria undergo a host-directed multistep differentiation process culminating in the formation of elongated and branched polyploid bacteria with definitive loss of cell division ability. The plant factors are nodule-specific symbiotic peptides. Approximately 600 of them are nodule-specific cysteine-rich (NCR) peptides produced in the rhizobium-infected plant cells. NCRs are targeted to the endosymbionts, and concerted action of different sets of peptides governs different stages of endosymbiont maturation, whereas the symbiotic function of individual NCRs is unknown. This study focused on NCR247, a cationic peptide exhibiting in vitro antimicrobial activities. We show that NCR247 acts in those nodule cells where bacterial cell division is arrested and cell elongation begins. NCR247 penetrates the bacteria and forms complexes with many bacterial proteins. Interaction with FtsZ required for septum formation is one of the host interventions for inhibiting bacterial cell division. Complex formation with the ribosomal proteins affects translation and contributes to altered proteome and physiology of the endosymbiont. Binding to the chaperone GroEL amplifies the NCR247-modulated biological processes. We show that GroEL1 of Sinorhizobium meliloti is required for efficient infection, terminal differentiation, and nitrogen fixation.


Assuntos
Medicago truncatula/metabolismo , Peptídeos/fisiologia , Proteínas de Plantas/química , Simbiose , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Proteínas de Bactérias/biossíntese , Medicago truncatula/microbiologia , Fixação de Nitrogênio , Ligação Proteica
15.
Biomed Microdevices ; 17(6): 108, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26482154

RESUMO

Blood flow presents several interesting phenomena in microcirculation that can be used to develop microfluidic devices capable to promote blood cells separation and analysis in continuous flow. In the last decade there have been numerous microfluidic studies focused on the deformation of red blood cells (RBCs) flowing through geometries mimicking microvessels. In contrast, studies focusing on the deformation of white blood cells (WBCs) are scarce despite this phenomenon often happens in the microcirculation. In this work, we present a novel integrative microfluidic device able to perform continuous separation of a desired amount of blood cells, without clogging or jamming, and at the same time, capable to assess the deformation index (DI) of both WBCs and RBCs. To determine the DI of both WBCs and RBCs, a hyperbolic converging microchannel was used, as well as a suitable image analysis technique to measure the DIs of these blood cells along the regions of interest. The results show that the WBCs have a much lower deformability than RBCs when subjected to the same in vitro flow conditions, which is directly related to their cytoskeleton and nucleus contents. The proposed strategy can be easily transformed into a simple and inexpensive diagnostic microfluidic system to simultaneously separate and assess blood cells deformability.


Assuntos
Deformação Eritrocítica , Eritrócitos/citologia , Dispositivos Lab-On-A-Chip , Leucócitos/citologia , Técnicas Analíticas Microfluídicas/instrumentação , Desenho de Equipamento , Humanos , Processamento de Imagem Assistida por Computador , Contagem de Leucócitos
16.
Micromachines (Basel) ; 15(2)2024 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-38399009

RESUMO

This review attempts to provide a comprehensive assessment of recent methodologies, structures, and devices for pool boiling heat transfer enhancement. Several enhancement approaches relating to the underlying fluid route and the capability to eliminate incipient boiling hysteresis, augment the nucleate boiling heat transfer coefficient, and improve the critical heat flux are assessed. Hence, this study addresses the most relevant issues related to active and passive enhancement techniques and compound enhancement schemes. Passive heat transfer enhancement techniques encompass multiscale surface modification of the heating surface, such as modification with nanoparticles, tunnels, grooves, porous coatings, and enhanced nanostructured surfaces. Also, there are already studies on the employment of a wide range of passive enhancement techniques, like displaced enhancement, swirl flow aids, and bi-thermally conductive surfaces. Moreover, the combined usage of two or more enhancement techniques, commonly known as compound enhancement approaches, is also addressed in this survey. Additionally, the present work highlights the existing scarcity of sufficiently large available databases for a given enhancement methodology regarding the influencing factors derived from the implementation of innovative thermal management systems for temperature-sensitive electronic and power devices, for instance, material, morphology, relative positioning and orientation of the boiling surface, and nucleate boiling heat transfer enhancement pattern and scale. Such scarcity means the available findings are not totally accurate and suitable for the design and implementation of new thermal management systems. The analysis of more than 100 studies in this field shows that all such improvement methodologies aim to enhance the nucleate boiling heat transfer parameters of the critical heat flux and nucleate heat transfer coefficient in pool boiling scenarios. Finally, diverse challenges and prospects for further studies are also pointed out, aimed at developing important in-depth knowledge of the underlying enhancement mechanisms of such techniques.

17.
Micromachines (Basel) ; 15(6)2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38930640

RESUMO

Polydimethylsiloxane (PDMS) has attracted great attention in various fields due to its excellent properties, but its inherent hydrophobicity presents challenges in many applications that require controlled wettability. The purpose of this review is to provide a comprehensive overview of some key strategies for modifying the wettability of PDMS surfaces by providing the main traditional methods for this modification and the results of altering the contact angle and other characteristics associated with this property. Four main technologies are discussed, namely, oxygen plasma treatment, surfactant addition, UV-ozone treatment, and the incorporation of nanomaterials, as these traditional methods are commonly selected due to the greater availability of information, their lower complexity compared to the new techniques, and the lower cost associated with them. Oxygen plasma treatment is a widely used method for improving the hydrophilicity of PDMS surfaces by introducing polar functional groups through oxidation reactions. The addition of surfactants provides a versatile method for altering the wettability of PDMS, where the selection and concentration of the surfactant play an important role in achieving the desired surface properties. UV-ozone treatment is an effective method for increasing the surface energy of PDMS, inducing oxidation, and generating hydrophilic functional groups. Furthermore, the incorporation of nanomaterials into PDMS matrices represents a promising route for modifying wettability, providing adjustable surface properties through controlled dispersion and interfacial interactions. The synergistic effect of nanomaterials, such as nanoparticles and nanotubes, helps to improve wetting behaviour and surface energy. The present review discusses recent advances of each technique and highlights their underlying mechanisms, advantages, and limitations. Additionally, promising trends and future prospects for surface modification of PDMS are discussed, and the importance of tailoring wettability for applications ranging from microfluidics to biomedical devices is highlighted. Traditional methods are often chosen to modify the wettability of the PDMS surface because they have more information available in the literature, are less complex than new techniques, and are also less expensive.

18.
Polymers (Basel) ; 16(10)2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38794609

RESUMO

Over the last decade, researchers have developed a variety of new analytical and clinical diagnostic devices. These devices are predominantly based on microfluidic technologies, where biological samples can be processed and manipulated for the collection and detection of important biomolecules. Polydimethylsiloxane (PDMS) is the most commonly used material in the fabrication of these microfluidic devices. However, it has a hydrophobic nature (contact angle with water of 110°), leading to poor wetting behavior and issues related to the mixing of fluids, difficulties in obtaining uniform coatings, and reduced efficiency in processes such as plasma separation and molecule detection (protein adsorption). This work aimed to consider the fabrication aspects of PDMS microfluidic devices for biological applications, such as surface modification methods. Therefore, we studied and characterized two methods for obtaining hydrophilic PDMS surfaces: surface modification by bulk mixture and the surface immersion method. To modify the PDMS surface properties, three different surfactants were used in both methods (Pluronic® F127, polyethylene glycol (PEG), and polyethylene oxide (PEO)) at different percentages. Water contact angle (WCA) measurements were performed to evaluate the surface wettability. Additionally, capillary flow studies were performed with microchannel molds, which were produced using stereolithography combined with PDMS double casting and replica molding procedures. A PDMS microfluidic device for blood plasma separation was also fabricated by soft lithography with PDMS modified by PEO surfactant at 2.5% (v/v), which proved to be the best method for making the PDMS hydrophilic, as the WCA was lower than 50° for several days without compromising the PDMS's optical properties. Thus, this study indicates that PDMS surface modification shows great potential for enhancing blood plasma separation efficiency in microfluidic devices, as it facilitates fluid flow, reduces cell aggregations and the trapping of air bubbles, and achieves higher levels of sample purity.

19.
Front Immunol ; 15: 1354479, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38444856

RESUMO

Introduction: The inflammatory response after spinal cord injury (SCI) is an important contributor to secondary damage. Infiltrating macrophages can acquire a spectrum of activation states, however, the microenvironment at the SCI site favors macrophage polarization into a pro-inflammatory phenotype, which is one of the reasons why macrophage transplantation has failed. Methods: In this study, we investigated the therapeutic potential of the macrophage secretome for SCI recovery. We investigated the effect of the secretome in vitro using peripheral and CNS-derived neurons and human neural stem cells. Moreover, we perform a pre-clinical trial using a SCI compression mice model and analyzed the recovery of motor, sensory and autonomic functions. Instead of transplanting the cells, we injected the paracrine factors and extracellular vesicles that they secrete, avoiding the loss of the phenotype of the transplanted cells due to local environmental cues. Results: We demonstrated that different macrophage phenotypes have a distinct effect on neuronal growth and survival, namely, the alternative activation with IL-10 and TGF-ß1 (M(IL-10+TGF-ß1)) promotes significant axonal regeneration. We also observed that systemic injection of soluble factors and extracellular vesicles derived from M(IL-10+TGF-ß1) macrophages promotes significant functional recovery after compressive SCI and leads to higher survival of spinal cord neurons. Additionally, the M(IL-10+TGF-ß1) secretome supported the recovery of bladder function and decreased microglial activation, astrogliosis and fibrotic scar in the spinal cord. Proteomic analysis of the M(IL-10+TGF-ß1)-derived secretome identified clusters of proteins involved in axon extension, dendritic spine maintenance, cell polarity establishment, and regulation of astrocytic activation. Discussion: Overall, our results demonstrated that macrophages-derived soluble factors and extracellular vesicles might be a promising therapy for SCI with possible clinical applications.


Assuntos
Interleucina-10 , Traumatismos da Medula Espinal , Humanos , Animais , Camundongos , Fator de Crescimento Transformador beta1 , Proteômica , Secretoma , Traumatismos da Medula Espinal/terapia
20.
Appl Environ Microbiol ; 79(21): 6737-46, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23995935

RESUMO

Leguminous plants establish symbiosis with nitrogen-fixing alpha- and betaproteobacteria, collectively called rhizobia, which provide combined nitrogen to support plant growth. Members of the inverted repeat-lacking clade of legumes impose terminal differentiation on their endosymbiotic bacterium partners with the help of the nodule-specific cysteine-rich (NCR) peptide family composed of close to 600 members. Among the few tested NCR peptides, cationic ones had antirhizobial activity measured by reduction or elimination of the CFU and uptake of the membrane-impermeable dye propidium iodide. Here, the antimicrobial spectrum of two of these peptides, NCR247 and NCR335, was investigated, and their effect on the transcriptome of the natural target Sinorhizobium meliloti was characterized. Both peptides were able to kill quickly a wide range of Gram-negative and Gram-positive bacteria; however, their spectra were only partially overlapping, and differences were found also in their efficacy on given strains, indicating that the actions of NCR247 and NCR335 might be similar though not identical. Treatment of S. meliloti cultures with either peptide resulted in a quick downregulation of genes involved in basic cellular functions, such as transcription-translation and energy production, as well as upregulation of genes involved in stress and oxidative stress responses and membrane transport. Similar changes provoked mainly in Gram-positive bacteria by antimicrobial agents were coupled with the destruction of membrane potential, indicating that it might also be a common step in the bactericidal actions of NCR247 and NCR335.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Membrana Celular/metabolismo , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Sinorhizobium meliloti/metabolismo , Transcriptoma/genética , Sequência de Aminoácidos , Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Catiônicos Antimicrobianos/metabolismo , Biologia Computacional , Cisteína/metabolismo , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica/genética , Dados de Sequência Molecular , Propídio , Análise de Sequência de RNA , Sinorhizobium meliloti/genética
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