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Materials (Basel) ; 14(7)2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33807282


The key goal of this study was to characterize polytetrafluoroethylene (PTFE) based composites with the addition of bronze particles and mineral fibers/particles. The addition of individual fillers was as follows: bronze-30-60 wt.%, glass fibers-15-25 wt.%, coke flakes-25 wt.% and graphite particles-5 wt.%. Both static and dynamic tests were performed and the obtained results were compared with the microscopic structure of the obtained fractures. The research showed that the addition of 60 wt.% bronze and other mineral fillers improved the values obtained in the static compression test and in the case of composites with 25 wt.% glass fibers the increase was about 60%. Fatigue tests have been performed for the compression-compression load up to 100,000 cycles. All tested composites show a significant increase in the modulus as compared to the values obtained in the static compression test. The highest increase in the modulus in the dynamic test was obtained for composites with 25 wt.% of glass fibers (increase by 85%) and 25 wt.% of coke flakes (increase by 77%), while the lowest result was obtained for the lowest content of bronze particles (decrease by 8%). Dynamic tests have shown that composites with "semi-spherical" particles are characterized by the longest service life and a slower fatigue crack propagation rate than in the case of the long glass fibers. In addition, studies have shown that particles with smaller sizes and more spherical shape have a higher ability to dissipate mechanical energy, which allows their use in friction nodes. On the other hand, composites with glass fiber and graphite particles can be successfully used in applications requiring high stiffness with low amplitude vibrations.

Molecules ; 24(19)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31574925


Biodegradable composites based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate), reinforced with 7.5% or 15% by weight of wood fibers (WF) or basalt fibers (BF) were fabricated by injection molding. BF reinforced composites showed improvement in all properties, whereas WF composites showed an increase in Young's modulus values, but a drop in strength and impact properties. When compared with the unmodified polymer, composites with 15% by weight of BF showed an increase of 74% in Young's modulus and 41% in impact strength. Furthermore, the experimentally measured values of Young's modulus were compared with values obtained in various theoretical micromechanical models. The Haplin-Kardas model was found to be in near approximation to the experimental data. The morphological aspect of the biocomposites was studied using scanning electron microscopy to obtain the distribution and interfacial adhesion of the fibers. Additionally, biodegradation tests of the biocomposites were performed in saline solution at 40 °C by studying the weight loss and mechanical properties. It was observed that the presence of fibers affects the rate of water absorption and the highest rate was seen for composites with 15% by weight of WF. This is dependent on the nature of the fiber. After both the first and second weeks mechanical properties decreased slightly about 10%.

Materiais Biocompatíveis/química , Fenômenos Químicos , Fenômenos Mecânicos , Poliésteres/química , Teste de Materiais , Microscopia Eletrônica de Varredura , Temperatura , Madeira/química
Neuropharmacology ; 143: 327-338, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30219501


Histaminergic (HA) neurons located in the tuberomamillary nucleus (TMN) of the posterior hypothalamus fire exclusively during waking and support many physiological functions. We investigated the role of the endovanilloid N-oleoyldopamine (OLDA) in TMN, where dopamine synthesis and its conjugation with oleic acid likely occur. We show that several known targets of OLDA including TRPV1 and cannabinoid receptors are expressed in HA neurons. In contrast to capsaicin, which failed to increase firing of HA neurons in TRPV1 knockout mice (TRPVI KO), OLDA was still able to induce excitation. This excitation was not sensitive to the blockade of cannabinoid receptors 1 and 2 and could result from OLDA interaction with GPR119, as the ligand of GPR119, oleoylethanolamide (OEA), also increased the firing of HA neurons. However, we ruled out this possibility as OEA- (but not OLDA-) excitation was abolished by the PPAR (peroxisome proliferator activated receptor) alpha antagonist MK886. The dopamine uptake blocker nomifensine blanked OLDA-excitation and dopamine receptor antagonists abolished the OLDA action in TRPV1 KO mice. Therefore OLDA excites HA neurons through multiple targets suggesting a central role of the histaminergic system in the behavioral stimulation seen after systemic OLDA application.

Dopamina/análogos & derivados , Histamina/metabolismo , Região Hipotalâmica Lateral/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurotransmissores/farmacologia , Animais , Dopamina/farmacologia , Região Hipotalâmica Lateral/citologia , Região Hipotalâmica Lateral/crescimento & desenvolvimento , Região Hipotalâmica Lateral/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/citologia , Neurônios/metabolismo , Técnicas de Patch-Clamp , Canais de Cátion TRPV/genética , Canais de Cátion TRPV/metabolismo , Técnicas de Cultura de Tecidos
Neuropharmacology ; 119: 111-122, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28400256


N-oleoyl-dopamine (OLDA) is an amide of dopamine and oleic acid, synthesized in catecholaminergic neurons. The present study investigates OLDA targets in midbrain dopaminergic (DA) neurons. Substantia Nigra compacta (SNc) DA neurons recorded in brain slices were excited by OLDA in wild type mice. In transient receptor potential vanilloid 1 (TRPV1) knockout (KO) mice, however, SNc DA neurons displayed sustained inhibition of firing. In the presence of the dopamine type 2 receptor (D2R) antagonist sulpiride or the dopamine transporter blocker nomifensine no such inhibition was observed. Under sulpiride OLDA slightly excited SNc DA neurons, an action abolished upon combined application of the cannabinoid1 and 2 receptor antagonists AM251 and AM630. In ventral tegmental area (VTA) DA neurons from TRPV1 KO mice a transient inhibition of firing by OLDA was observed. Thus OLDA modulates the firing of nigrostriatal DA neurons through interactions with TRPV1, cannabinoid receptors and dopamine uptake. These findings suggest further development of OLDA-like tandem molecules for the treatment of movement disorders including Parkinson's disease.

Dopaminérgicos/farmacologia , Dopamina/análogos & derivados , Neurônios Dopaminérgicos/efeitos dos fármacos , Mesencéfalo/citologia , Canais de Cátion TRPV/metabolismo , Acrilamidas/farmacologia , Potenciais de Ação/efeitos dos fármacos , Fatores Etários , Animais , Animais Recém-Nascidos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Antagonistas de Receptores de Canabinoides/farmacologia , Dopamina/farmacologia , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Inibição Neural/efeitos dos fármacos , Técnicas de Patch-Clamp , Piperidinas/farmacologia , Pirazóis/farmacologia , Canais de Cátion TRPV/antagonistas & inibidores , Canais de Cátion TRPV/genética , Tirosina 3-Mono-Oxigenase/metabolismo
Toxicol Ind Health ; 27(4): 315-21, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-20947654


We analyzed whether polychlorinated biphenyls (PCBs) interfere with the activity of 17 ß-estradiol in the proliferation and apoptosis of the MCF-7 cell line. MCF-7 cells were cultured in Dulbecco's modified Eagle's medium (DMEM) without phenol red supplemented with 5% charcoal-treated fetal bovine serum (CD-FBS) for 3 days with 10 nM 17 ß-estradiol or 0.1 µM, 0.5 µM and 1 µM of the tested PCB congeners (118, 138, 153 and 180), or both. Cell proliferation was determined by measuring 5-bromo-2'-deoxyuridine (BrdU) incorporation, and cell apoptosis was measured by caspase-9 activity. From the PCB congeners tested, PCB138 and 153 had the highest stimulatory effects on basal cell proliferation as well as the highest inhibitory actions on basal caspase-9 activity. The proliferative and anti-apoptotic actions of PCB138 and 153 were still observed in the presence of 17 ß-estradiol, while the actions of PCB118 and 180 were reversed. In conclusion, the results of this study suggest the possibility that PCB138 and 153 contribute to the action of endogenous 17 ß-estradiol on cell proliferation and apoptosis in the breast cancer cell line MCF-7.

Apoptose/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Estradiol/toxicidade , Bifenilos Policlorados/toxicidade , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Bromodesoxiuridina/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Interações Medicamentosas , Feminino , Humanos