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1.
Biomed Res Int ; 2021: 8899699, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33628828

RESUMO

The in vivo characterization of the passive mechanical properties of the human triceps surae musculotendinous unit is important for gaining a deeper understanding of the interactive responses of the tendon and muscle tissues to loading during passive stretching. This study sought to quantify a comprehensive set of passive muscle-tendon properties such as slack length, stiffness, and the stress-strain relationship using a combination of ultrasound imaging and a three-dimensional motion capture system in healthy adults. By measuring tendon length, the cross-section areas of the Achilles tendon subcompartments (i.e., medial gastrocnemius and soleus aspects), and the ankle torque simultaneously, the mechanical properties of each individual compartment can be specifically identified. We found that the medial gastrocnemius (GM) and soleus (SOL) aspects of the Achilles tendon have similar mechanical properties in terms of slack angle (GM: -10.96° ± 3.48°; SOL: -8.50° ± 4.03°), moment arm at 0° of ankle angle (GM: 30.35 ± 6.42 mm; SOL: 31.39 ± 6.42 mm), and stiffness (GM: 23.18 ± 13.46 Nmm-1; SOL: 31.57 ± 13.26 Nmm-1). However, maximal tendon stress in the GM was significantly less than that in SOL (GM: 2.96 ± 1.50 MPa; SOL: 4.90 ± 1.88 MPa, p = 0.024), largely due to the higher passive force observed in the soleus compartment (GM: 99.89 ± 39.50 N; SOL: 174.59 ± 79.54 N, p = 0.020). Moreover, the tendon contributed to more than half of the total muscle-tendon unit lengthening during the passive stretch. This unequal passive stress between the medial gastrocnemius and the soleus tendon might contribute to the asymmetrical loading and deformation of the Achilles tendon during motion reported in the literature. Such information is relevant to understanding the Achilles tendon function and loading profile in pathological populations in the future.


Assuntos
Tendão do Calcâneo/fisiologia , Fenômenos Biomecânicos/fisiologia , Músculo Esquelético/fisiologia , Adulto , Articulação do Tornozelo/fisiologia , Eletromiografia , Feminino , Humanos , Masculino , Amplitude de Movimento Articular/fisiologia , Torque
2.
PLoS Genet ; 15(12): e1008455, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31800589

RESUMO

SLC18B1 is a sister gene to the vesicular monoamine and acetylcholine transporters, and the only known polyamine transporter, with unknown physiological role. We reveal that Slc18b1 knock out mice has significantly reduced polyamine content in the brain providing the first evidence that Slc18b1 is functionally required for regulating polyamine levels. We found that this mouse has impaired short and long term memory in novel object recognition, radial arm maze and self-administration paradigms. We also show that Slc18b1 KO mice have altered expression of genes involved in Long Term Potentiation, plasticity, calcium signalling and synaptic functions and that expression of components of GABA and glutamate signalling are changed. We further observe a partial resistance to diazepam, manifested as significantly lowered reduction in locomotion after diazepam treatment. We suggest that removal of Slc18b1 leads to reduction of polyamine contents in neurons, resulting in reduced GABA signalling due to long-term reduction in glutamatergic signalling.


Assuntos
Encéfalo/metabolismo , Proteínas de Transporte de Cátions/genética , Memória de Longo Prazo , Memória de Curto Prazo , Poliaminas/metabolismo , Animais , Sinalização do Cálcio , Técnicas de Inativação de Genes , Ácido Glutâmico/metabolismo , Aprendizagem em Labirinto , Camundongos , Plasticidade Neuronal , Ácido gama-Aminobutírico/metabolismo
3.
Nano Lett ; 19(10): 7155-7163, 2019 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-31512480

RESUMO

The guided gliding of cytoskeletal filaments, driven by biomolecular motors on nano/microstructured chips, enables novel applications in biosensing and biocomputation. However, expensive and time-consuming chip production hampers the developments. It is therefore important to establish protocols to regenerate the chips, preferably without the need to dismantle the assembled microfluidic devices which contain the structured chips. We here describe a novel method toward this end. Specifically, we use the small, nonselective proteolytic enzyme, proteinase K to cleave all surface-adsorbed proteins, including myosin and kinesin motors. Subsequently, we apply a detergent (5% SDS or 0.05% Triton X100) to remove the protein remnants. After this procedure, fresh motor proteins and filaments can be added for new experiments. Both, silanized glass surfaces for actin-myosin motility and pure glass surfaces for microtubule-kinesin motility were repeatedly regenerated using this approach. Moreover, we demonstrate the applicability of the method for the regeneration of nano/microstructured silicon-based chips with selectively functionalized areas for supporting or suppressing gliding motility for both motor systems. The results substantiate the versatility and a promising broad use of the method for regenerating a wide range of protein-based nano/microdevices.


Assuntos
Técnicas Biossensoriais/instrumentação , Cinesina/química , Miosinas/química , Nanoestruturas/química , Adsorção , Animais , Citoesqueleto/química , Endopeptidase K/química , Desenho de Equipamento , Proteínas Imobilizadas/química , Octoxinol/química , Coelhos , Propriedades de Superfície
4.
Nano Lett ; 18(8): 4796-4802, 2018 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-30001138

RESUMO

Semiconductor nanowires can act as nanoscaled optical fibers, enabling them to guide and concentrate light emitted by surface-bound fluorophores, potentially enhancing the sensitivity of optical biosensing. While parameters such as the nanowire geometry and the fluorophore wavelength can be expected to strongly influence this lightguiding effect, no detailed description of their effect on in-coupling of fluorescent emission is available to date. Here, we use confocal imaging to quantify the lightguiding effect in GaP nanowires as a function of nanowire geometry and light wavelength. Using a combination of finite-difference time-domain simulations and analytical approaches, we identify the role of multiple waveguide modes for the observed lightguiding. The normalized frequency parameter, based on the step-index approximation, predicts the lightguiding ability of the nanowires as a function of diameter and fluorophore wavelength, providing a useful guide for the design of optical biosensors based on nanowires.


Assuntos
Técnicas Biossensoriais/instrumentação , Corantes Fluorescentes/química , Gálio/química , Nanofios/química , Fosfinas/química , Óxido de Alumínio/química , Fluorescência , Luz , Fibras Ópticas , Tamanho da Partícula , Semicondutores , Propriedades de Superfície
5.
Langmuir ; 34(30): 8777-8784, 2018 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-29969272

RESUMO

Molecular motor-based nanodevices require organized cytoskeletal filament guiding along motility-promoting tracks, confined by motility-inhibiting walls. One way to enhance motility quality on the tracks, particularly in terms of filament velocity but also the fraction of motile filaments, is to optimize the surface hydrophobicity. We have investigated the potential to achieve this for the actin-myosin II motor system on trimethylchlorosilane (TMCS)-derivatized SiO2 surfaces to be used as channel floors in nanodevices. We have also investigated the ability to supress motility on two new polymer resists, TU7 (for nanoimprint lithography) and CSAR 62 (for electron beam and deep UV lithography), to be used as channel walls. We developed a chemical-vapor deposition tool for silanizing SiO2 surfaces in a controlled environment to achieve different surface hydrophobicities (measured by water contact angle). In contrast to previous work, we were able to fabricate a wide range of contact angles by varying the silanization time and chamber pressure using only one type of silane. This resulted in a significant improvement of the silanization procedure, producing a predictable contact angle on the surface and thereby predictable quality of the heavy meromyosin (HMM)-driven actin motility with regard to velocity. We observed a high degree of correlation between the filament sliding velocity and contact angle in the range 10-86°, expanding the previously studied range. We found that the sliding velocity on TU7 surfaces was superior to that on CSAR 62 surfaces despite similar contact angles. In addition, we were able to suppress the motility on both TU7 and CSAR 62 by plasma oxygen treatment before silanization. These results are discussed in relation to previously proposed surface adsorption mechanisms of HMM and their relationship to the water contact angle. Additionally, the results are considered for the development of actin-myosin based nanodevices with superior performance with respect to actin-myosin functionality.


Assuntos
Actinas/química , Materiais Revestidos Biocompatíveis , Miosinas/química , Nanotecnologia/métodos , Dióxido de Silício/química , Polímeros , Propriedades de Superfície
6.
Front Mol Neurosci ; 10: 11, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28179877

RESUMO

Characterization of orphan transporters is of importance due to their involvement in cellular homeostasis but also in pharmacokinetics and pharmacodynamics. The tissue and cellular localization, as well as function, is still unknown for many of the solute carriers belonging to the major facilitator superfamily (MFS) Pfam clan. Here, we have characterized two putative novel transporters MFSD14A (HIAT1) and MFSD14B (HIATL1) in the mouse central nervous system and found protein staining throughout the adult mouse brain. Both transporters localized to neurons and MFSD14A co-localized with the Golgi marker Giantin in primary embryonic cortex cultures, while MFSD14B staining co-localized with an endoplasmic retention marker, KDEL. Based on phylogenetic clustering analyses, we predict both to have organic substrate profiles, and possible involvement in energy homeostasis. Therefore, we monitored gene regulation changes in mouse embryonic primary cultures after amino acid starvations and found both transporters to be upregulated after 3 h of starvation. Interestingly, in mice subjected to 24 h of food starvation, both transporters were downregulated in the hypothalamus, while Mfsd14a was also downregulated in the brainstem. In addition, in mice fed a high fat diet (HFD), upregulation of both transporters was seen in the striatum. Both MFSD14A and MFSD14B were intracellular neuronal membrane-bound proteins, expressed in the Golgi and Endoplasmic reticulum, affected by both starvation and HFD to varying degree in the mouse brain.

7.
BMC Neurosci ; 17(1): 43, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27364523

RESUMO

BACKGROUND: MCT14 (SLC16A14) is an orphan member of the monocarboxylate transporter (MCT) family, also known as the SLC16 family of secondary active transmembrane transporters. Available expression data for this transporter is limited, and in this paper we aim to characterize MCT14 with respect to tissue distribution and cellular localization in mouse brain. RESULTS: Using qPCR, we found that Slc16a14 mRNA was highly abundant in mouse kidney and moderately in central nervous system, testis, uterus and liver. Using immunohistochemistry and in situ hybridization, we determined that MCT14 was highly expressed in excitatory and inhibitory neurons as well as epithelial cells in the mouse brain. The expression was exclusively localized to the soma of neurons. Furthermore, we showed with our phylogenetic analysis that MCT14 most closely relate to the aromatic amino acid- and thyroid-hormone transporters MCT8 (SLC16A2) and MCT10 (SLC16A10), in addition to the carnitine transporter MCT9 (SLC16A9). CONCLUSIONS: We provide here the first histological mapping of MCT14 in the brain and our data are consistent with the hypothesis that MCT14 is a neuronal aromatic-amino-acid transporter.


Assuntos
Encéfalo/metabolismo , Proteínas de Transporte/metabolismo , Rim/metabolismo , Animais , Western Blotting , Encéfalo/citologia , Proteínas de Transporte/genética , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Hibridização In Situ , Rim/citologia , Fígado/citologia , Fígado/metabolismo , Masculino , Camundongos , Neurônios/citologia , Neurônios/metabolismo , Células PC12 , Filogenia , RNA Mensageiro/metabolismo , Ratos , Reação em Cadeia da Polimerase em Tempo Real , Testículo/citologia , Testículo/metabolismo , Transfecção , Útero/citologia , Útero/metabolismo
8.
BMC Med Imaging ; 13: 16, 2013 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-23758876

RESUMO

BACKGROUND: Tissue Velocity Imaging (TVI) is an ultrasound based technique used for quantitative analysis of the cardiac function and has earlier been evaluated according to myocardial velocities. Recent years several studies have reported applying TVI in the analysis of skeletal muscles. Skeletal tissue velocities can be very low. In particular, when performing isometric contractions or contractions of low force level the velocities may be much lower compared to the myocardial tissue velocities. METHODS: In this study TVI was evaluated for estimation of tissue velocities below the typical myocardial velocities. An in-house phantom was used to see how different PRF-settings affected the accuracy of the velocity estimations. RESULTS: With phantom peak velocity at 0.03 cm/s the error ranged from 31% up to 313% with the different PRF-settings in this study. For the peak velocities at 0.17 cm/s and 0.26 cm/s there was no difference in error with tested PFR settings, it is kept approximately around 20%. CONCLUSIONS: The results from the present study showed that the PRF setting did not seem to affect the accuracy of the velocity estimation at tissue velocities above 0.17 cm/s. However at lower velocities (0.03 cm/s) the setting was crucial for the accuracy. The PRF should therefore preferable be reduced when the method is applied in low-level muscle contraction.


Assuntos
Técnicas de Imagem por Elasticidade/instrumentação , Técnicas de Imagem por Elasticidade/métodos , Interpretação de Imagem Assistida por Computador/métodos , Contração Muscular/fisiologia , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologia , Imagens de Fantasmas , Algoritmos , Biomimética/métodos , Humanos , Aumento da Imagem/métodos , Esforço Físico/fisiologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
9.
Ultrasound Med Biol ; 37(7): 1151-60, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21640478

RESUMO

Tissue velocity imaging (TVI) is a Doppler based ultrasound technique that can be used to study regional deformation in skeletal muscle tissue. The aim of this study was to develop a biomechanical model to describe the TVI strain's dependency on the pennation angle. We demonstrate its impact as the subsequent strain measurement error using dynamic elbow contractions from the medial and the lateral part of biceps brachii at two different loadings; 5% and 25% of maximum voluntary contraction (MVC). The estimated pennation angles were on average about 4° in extended position and increased to a maximal of 13° in flexed elbow position. The corresponding relative angular error spread from around 7% up to around 40%. To accurately apply TVI on skeletal muscles, the error due to angle changes should be compensated for. As a suggestion, this could be done according to the presented model.


Assuntos
Articulação do Cotovelo/diagnóstico por imagem , Articulação do Cotovelo/fisiologia , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologia , Ultrassonografia Doppler/métodos , Adulto , Fenômenos Biomecânicos , Humanos , Masculino , Análise de Regressão , Processamento de Sinais Assistido por Computador , Software
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