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1.
Res Vet Sci ; 137: 208-216, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34020336

RESUMO

The present study aimed to verify the changes in the expression levels of 13 candidate genes associated with chemotherapy resistance and to construct a scoring system to predict resistance to these drugs. The expression levels of the 13 candidate genes were compared between 20 dogs with lymphoma that were sensitive to drugs used in CHOP-based protocol and 16 dogs with lymphoma that were resistant to these drugs. The expression levels of six genes; ASNS, CCR3, CALCA, FCER1A, LOC448801, and EDNRB were significantly different between the two groups. A scoring system to predict resistance to cyclophosphamide, doxorubicin and vincristine, which are used in CHOP-based protocol, was constructed based on expression levels of the six genes in these 36 dogs using logistic regression models. After internal validation, sensitivity and specificity of the scoring system were 0.759 and 0.853, respectively. External validation was conducted in another cohort of 33 dogs with lymphoma, and sensitivity and specificity of the scoring system were 0.800 and 0.696, respectively. In conclusion, this study identified six genes associated with resistance to drugs used in CHOP-based protocol in canine lymphoma and proposed a novel scoring system to predict resistance to these drugs. This system might be beneficial in selecting the most appropriate chemotherapy protocol for individual dogs with lymphoma.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Doenças do Cão/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/genética , Linfoma/veterinária , Transcriptoma , Animais , Estudos de Coortes , Ciclofosfamida/uso terapêutico , Cães , Doxorrubicina/uso terapêutico , Feminino , Linfoma/tratamento farmacológico , Masculino , Prednisona/uso terapêutico , Projetos de Pesquisa , Vincristina/uso terapêutico
2.
Phys Rev E ; 97(6-1): 062124, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30011507

RESUMO

For liquid rubidium the Stokes-Einstein (SE) relation is well fulfilled near the melting point with an effective hydrodynamic diameter, which agrees well with a value from structural investigations. A wealth of thermodynamic and microscopic data exists for a wide range of temperatures for liquid rubidium and hence it represents a good test bed to challenge the SE relation with rising temperature from an experimental point of view. We performed classical molecular dynamics simulations to complement the existing experimental data using a pseudopotential, which describes perfectly the structure and dynamics of liquid rubidium. The derived SE relation from combining experimental shear viscosity data with simulated diffusion coefficients reveals a weak violation at about 1.3T_{melting}≈400 K. The microscopic relaxation dynamics on nearest neighbor distances from neutron spectroscopy demonstrate distinct changes in the amplitude with rising temperature. The derived average relaxation time for density fluctuations on this length scale shows a non-Arrhenius behavior, with a slope change around 1.5T_{melting}≈450 K. Combining the simulated macroscopic self-diffusion coefficient with that microscopic average relaxation time, a distinct violation of the SE relation in the same temperature range can be demonstrated. One can conclude that the changes in the collective dynamics, a mirror of the correlated movements of the particles, are at the origin for the violation of the SE relation. The changes in the dynamics can be understood as a transition from a more viscous liquid metal to a more fluid-like liquid above the crossover temperature range of 1.3-1.5 T_{melting}. The decay of the amplitude of density fluctuations in liquid aluminium, lead, and rubidium demonstrates a remarkable agreement and points to a universal thermal crossover in the dynamics of liquid metals.

3.
Rev Epidemiol Sante Publique ; 65(4): 277-284, 2017 Aug.
Artigo em Francês | MEDLINE | ID: mdl-28410864

RESUMO

BACKGROUND: In Algeria, few studies have been conducted to determine the prevalence of genetic and environmental risk factors of cardiovascular diseases as a function of residence. The objective of this study was therefore to determine the prevalence of cardiovascular risk factors according to sex and age in urban and rural communities in the Wilaya of Tlemcen (Algeria). MATERIAL AND METHODS: A population survey was conducted on a representative sample of 864 individuals aged 20years and over, among inhabitants in urban and rural communes in the Wilaya of Tlemcen. Each subject answered the questionnaire on cardiovascular risk factors, underwent a physical examination and had a blood sample drawn. RESULTS: The prevalence of hypercholesterolemia was 6.6%, it was found to be higher in urban areas (8.4%) than in rural areas (4.6%). The prevalence of low HDL cholesterol levels was higher in urban (28.8%) than rural (23.9%) areas. The prevalence of family history of cardiovascular disease did not differ between the two sexes and between urban (15.7%) and rural (14.0%) areas. The prevalence of hypertension was higher in urban (28.0%) than in rural (16.8%) areas, and was highest among women aged 65 years or older in urban areas (67.3%) and in rural areas (66.6%). The prevalence of diabetes was higher among women living in urban areas (21.4%) compared with rural areas (15.4%). Obesity was much more frequent among women than among men in urban areas (24.7% in women and 9.5% in men) and in rural areas (28.3% in women and 8.3% in men). The prevalence of smoking was 45.8% for men and with no significant variations between urban areas and rural areas. CONCLUSION: The prevalence of cardiovascular risk factors according to sex and age in the two communes are high in two communes in the Wilaya of Tlemcen. However, the prevalence of hypertension, hypercholesterolemia and diabetes were higher in women in urban than in rural areas. This finding focuses attention on the need for measures to reduce the prevalence of these cardiovascular risk factors in these communities. Factors such as sex age and area of residence are indicators to consider when targeting interventions.


Assuntos
Doenças Cardiovasculares/epidemiologia , População Rural/estatística & dados numéricos , População Urbana/estatística & dados numéricos , Adulto , Idoso , Idoso de 80 Anos ou mais , Argélia/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Adulto Jovem
4.
J Obstet Gynaecol ; 35(7): 711-5, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25543526

RESUMO

Endometriosis is a chronic gynaecological disorder that is accompanied by inflammation and oxidative stress. Atherosclerosis has a long subclinical progression in arteries of children and young adults decades before overt clinical manifestations of the disease. In this study, we determined arterial stiffness by measuring brachial-ankle pulse wave velocity (baPWV) in women with endometriosis to assess the presence of subclinical atherosclerosis. We also measured markers of inflammation and oxidative stress in women with endometriosis. baPWV in women with endometriosis aged over 30 years was significantly higher than that in women without endometriosis aged over 30 years (p < 0.05), but not in women aged less than 30. Serum high-sensitivity C-reactive protein level in women with endometriosis was significantly higher than that in controls (p < 0.05). Young women with endometriosis show significantly increased arterial stiffness, suggesting that women with endometriosis need to be cautious of the future onset of atherosclerosis.


Assuntos
Endometriose/fisiopatologia , Rigidez Vascular , Adulto , Proteína C-Reativa/metabolismo , Antígeno Ca-125/sangue , Estudos de Casos e Controles , Endometriose/sangue , Feminino , Humanos , Análise de Onda de Pulso
6.
Climacteric ; 17(2): 191-6, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24164272

RESUMO

Abstract Background Ultra-low-dose estradiol is known to improve menopausal symptoms and increase bone mineral density. However, the effect of ultra-low-dose estradiol on vascular function has not been clarified. Objectives We examined the effects of ultra-low-dose estradiol on brachial-ankle pulse wave velocity (baPWV) and circulating markers of cardiovascular risk. Patients and methods Twenty-eight postmenopausal women were enrolled in this study. Fourteen women received oral estradiol (0.5 mg) and dydrogesterone (5 mg) every day for 12 months (ultra-low-dose group) as hormone replacement therapy (HRT) and 14 women as a control group did not receive HRT. The baPWV, lipid profiles, homeostasis model assessment of insulin resistance (HOMA-IR) and vascular inflammatory markers were measured. Results The baPWV level significantly decreased in the ultra-low-dose group (p = 0.037), while the baPWV level did not significantly change in the control group. HOMA-IR tended to decrease in the ultra-low-dose group (p = 0.076). Systolic blood pressure and diastolic blood pressure did not change significantly in either group. Conclusion An HRT regimen using oral ultra-low-dose estradiol and dydrogesterone has an effect on arterial stiffness and insulin resistance.


Assuntos
Doença da Artéria Coronariana/tratamento farmacológico , Didrogesterona/administração & dosagem , Estradiol/administração & dosagem , Terapia de Reposição de Estrogênios , Pós-Menopausa , Administração Oral , Colesterol/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Doença da Artéria Coronariana/sangue , Doença da Artéria Coronariana/fisiopatologia , Quimioterapia Combinada , Feminino , Humanos , Pessoa de Meia-Idade , Resultado do Tratamento , Triglicerídeos/sangue
7.
J Endocrinol Invest ; 36(11): 982-5, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23765418

RESUMO

OBJECTIVE: High-molecular weight (HMW) isoform level and HMW ratio have been shown to be better predictors of insulin sensitivity and metabolic syndrome than total adiponectin level.We examined the changes in circulating levels of HMW adiponectin and ratios of HMW to total adiponectin in women during the menopausal transition. METHODS: We conducted a cross-sectional study in 217 healthy women and divided them into 4 stages: 58 women in pre-menopausal, 69 women in perimenopausal, 62 women in early post-menopausal and 28 women in late post-menopausal phase. Serum levels of total adiponectin and HMW adiponectin were measured by an enzyme-linked immunosorbent assay. RESULTS: In late post-menopausal women, HMW adiponectin level was significantly higher than that in peri-menopausal women and the HMW to total adiponectin ratio was significantly lower than that in early post-menopausal women. In peri-menopausal women, HMW adiponectin level was significantly lower than that in pre-menopausal women and HMW to total adiponectin ratio was significantly lower than the ratios in pre-menopausal and early post-menopausal women. CONCLUSION: The ratio of HMW to total adiponectin is low in late post-menopausal women, though both levels of total and HMW adiponectin were high after menopause in our cross-sectional study.


Assuntos
Adiponectina/sangue , Pós-Menopausa/sangue , Adulto , Estudos Transversais , Feminino , Humanos , Resistência à Insulina , Menopausa/sangue , Síndrome Metabólica/sangue , Pessoa de Meia-Idade , Peso Molecular , Pré-Menopausa/sangue
8.
Phys Rev E Stat Nonlin Soft Matter Phys ; 83(3 Pt 1): 031201, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21517485

RESUMO

We propose a method by which the generalized transport properties and coefficients at all wavelengths and frequencies can be obtained by inversion of an exact kinetic equation. The necessary data are the density-density, energy-energy, and density-energy time correlation functions, which can be obtained by molecular-dynamics simulation. In addition, also the coupling between viscous stress tensor and energy flux vector can be obtained without approximation. This allows one to check the validity of the Markov assumption in a straightforward way. As a first test case, the theory is applied to liquid argon in two thermodynamic states. For this system, we calculate and discuss generalized thermodynamic (enthalpy, specific heats, and thermal expansion) and transport properties (longitudinal viscosity, thermal conductivity).


Assuntos
Física/métodos , Simulação por Computador , Temperatura Alta , Cinética , Cadeias de Markov , Modelos Estatísticos , Modelos Teóricos , Simulação de Dinâmica Molecular , Temperatura , Termodinâmica , Viscosidade
9.
Phys Rev E Stat Nonlin Soft Matter Phys ; 83(3 Pt 1): 031202, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21517486

RESUMO

In the present paper, we extend the method described in paper I [D. Bertolini and A. Tani, preceding paper, Phys. Rev. E 83, 031201 (2011)] to molecular liquids, which allows us to solve the exact kinetic equation proposed by de Schepper et al. [Phys. Rev. A 38, 271 (1988)] without approximations. In particular, generalized thermodynamic properties (enthalpy, specific heat, and thermal expansion coefficient) and transport properties (longitudinal viscosity, thermal conductivity) have been calculated for three liquids of increasing complexity, namely dimethyl sulfoxide, hydrogen fluoride, and SPC/E water. All results have been obtained by the molecular formalism as well as the atomic one, corrected for intramolecular correlations that are due to the models adopted. As done for simple liquids, the coupling between the viscous stress tensor and the energy flux vector has been calculated exactly. We also show that the Markov assumption for the dynamics related to thermal conductivity can only be adopted with caution.


Assuntos
Física/métodos , Simulação por Computador , Temperatura Alta , Cinética , Cadeias de Markov , Modelos Estatísticos , Modelos Teóricos , Simulação de Dinâmica Molecular , Temperatura , Termodinâmica , Viscosidade
10.
J Math Pures Appl ; 94(6): 571-596, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22163369

RESUMO

A topological derivative is defined, which is caused by kinking of a crack, thus, representing the topological change. Using variational methods, the anti-plane model of a solid subject to a non-penetration condition imposed at the kinked crack is considered. The objective function of the potential energy is expanded with respect to the diminishing branch of the incipient crack. The respective sensitivity analysis is provided by a Saint-Venant principle and a local decomposition of the solution of the variational problem in the Fourier series.

11.
Poult Sci ; 87(2): 329-34, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18212377

RESUMO

Forty-five strains of lactic acid bacteria were isolated from poultry feces sampled from an industrial farm located in the Nantes area (France), and most of them belong to the Streptococcus or Lactobacillus genus according to the results obtained by Galerie API and molecular methods. The most representative lactic acid bacteria strains were screened for antibacterial compound production against 2 indicator organisms (Listeria innocua F and Campylobacter jejuni 11168) by means of the agar diffusion test. Strain S37, identified as Enterococcus faecalis, exhibited a clear anti-listerial activity and a slight anti-Campylobacter activity, whereas strain S42, identified as Lactobacillus reuteri, exhibited only anti-Campylobacter activity. Regarding the results of proteolytic, heat, and neutralizing treatments of supernatants from the aforementioned strains, we can conclude that antagonism observed is attributed to antimicrobial peptide or bacteriocin in the case of strain S37, whereas it is ascribable to a nonbacteriocin, likely a reuterin, in the case of strain S42.


Assuntos
Antibacterianos/análise , Antibacterianos/farmacologia , Bactérias/isolamento & purificação , Bactérias/metabolismo , Galinhas/microbiologia , Fezes/química , Ácido Láctico/metabolismo , Animais , Bactérias/classificação , Bactérias/efeitos dos fármacos , Campylobacter/efeitos dos fármacos , Listeria/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Filogenia
12.
Toxicol In Vitro ; 22(2): 308-17, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17981006

RESUMO

Although several studies have shown that chlorhexidine digluconate (CHX) has bactericidal activity against periodontal pathogens and exerts toxic effects on periodontal tissues, few have been directed to evaluate the mechanisms underlying its adverse effects on these tissues. Therefore, the aim of the present study was to investigate the in vitro cytotoxicity of CHX on cells that could represent common targets for its action in the surgical procedures for the treatment of periodontitis and peri-implantitis and to elucidate its mechanisms of action. Osteoblastic, endothelial and fibroblastic cell lines were exposed to various concentrations of CHX for different times and assayed for cell viability and cell death. Also analysis of mitochondrial membrane potential, intracellular Ca2+ mobilization and reactive oxygen species (ROS) generation were done in parallel, to correlate CHX-induced cell damage with alterations in key parameters of cell homeostasis. CHX affected cell viability in a dose and time-dependent manners, particularly in osteoblasts. Its toxic effect consisted in the induction of apoptotic and autophagic/necrotic cell deaths and involved disturbance of mitochondrial function, intracellular Ca2+ increase and oxidative stress. These data suggest that CHX is highly cytotoxic in vitro and invite to a more cautioned use of the antiseptic in the oral surgical procedures.


Assuntos
Anti-Infecciosos Locais/toxicidade , Clorexidina/análogos & derivados , Células Endoteliais/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Osteoblastos/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Sinalização do Cálcio/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Clorexidina/toxicidade , Relação Dose-Resposta a Droga , Células Endoteliais/ultraestrutura , Fibroblastos/ultraestrutura , Humanos , Marcação In Situ das Extremidades Cortadas , Potenciais da Membrana/efeitos dos fármacos , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Membranas Mitocondriais/efeitos dos fármacos , Osteoblastos/ultraestrutura , Espécies Reativas de Oxigênio/metabolismo
13.
Appl Microbiol Biotechnol ; 68(5): 639-46, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15726348

RESUMO

A gene (pegC) encoding aldehyde dehydrogenase (ALDH) was located 3.4 kb upstream of a gene encoding polyethylene glycol (PEG) dehydrogenase (pegA) in Sphingomonas macrogoltabidus strain 103. ALDH was expressed in Escherichia coli and purified on a Ni-nitrilotriacetic acid agarose column. The recombinant enzyme was a homotetramer consisting of four 46.1-kDa subunits. The alignment of the putative amino acid sequence of the cloned enzyme showed high similarity with a group of NAD(P)-dependent ALDHs (identity 36-52%); NAD-binding domains (Rossmann fold and four glycine residues) and catalytic residues (Glu225 and Cys259) were well conserved. The cofactor, which was extracted from the purified enzyme, was tightly bound to the enzyme and identified as NADP. The enzyme contained 0.94 mol NADP per subunit. The enzyme was activated by Ca(2+), but by no other metals; no metal (Zn, Fe, Mg, or Mn) was detected in the purified recombinant enzyme. Activity was inhibited by p-chloromercuric benzoate, and heavy metals such as Hg, Cu, Pb and Cd, indicating that a cysteine residue is involved in the activity. Enzyme activity was independent of N,N-dimethyl-p-nitrosoaniline as an electron acceptor. Trans-4-(N,N-dimethylamino)-cinnamaldehyde was not oxidized as a substrate, but the compound worked as an inhibitor for the enzyme, as did pyrazole. The enzyme acted on n-aldehydes C(2)-C(14)) and PEG-aldehydes. Thus the enzyme was concluded to be a novel Ca(2+)-activating nicotinoprotein (NADP-containing) PEG-aldehyde dehydrogenase involved in the degradation of PEG in S. macrogoltabidus strain 103.


Assuntos
Álcool Desidrogenase/metabolismo , Aldeído Desidrogenase/metabolismo , Polietilenoglicóis/metabolismo , Aldeídos/metabolismo , Sequência de Aminoácidos , Catálise , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Sphingomonas/enzimologia , Sphingomonas/metabolismo , Especificidade por Substrato , Temperatura
14.
Rheumatology (Oxford) ; 44(5): 607-13, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15728417

RESUMO

OBJECTIVE: Evidence shows that peripheral nervous system (PNS) is involved in systemic sclerosis (SSc), but few morphological studies have assessed the ultrastructural pathological modifications. The aim was to study ultrastructural modifications of skin PNS fibres in SSc according to subsets [limited SSc (lSSc) and diffuse SSc (dSSc)] and phases (early and advanced) of the disease. METHODS: Skin biopsies were taken from the forearms of 23 SSc patients (11 lSSc and 12 dSSc) and 10 controls. Each biopsy was processed for transmission electron microscopy (TEM). RESULTS: At TEM, observation in skin from early lSSc, signs of inflammation were evident, while PNS fibres were not damaged. The microvascular wall showed hypertrophic endothelial cells bulging into the lumen. In advanced lSSc, fibrosis prevailed on inflammation and slight ultrastructural alterations of PNS fibres were evident in the papillary derma. In early dSSc, ultrastructural alterations of PNS fibres, similar to those observed in the advanced phase of lSSc, were found together with signs of inflammation and fibrosis. In advanced dSSc, in the papillary and reticular dermis PNS fibres were reduced and showed relevant ultrastructural alterations. CONCLUSIONS: In SSc, PNS ultrastructure damage is linked to the progression and severity of skin involvement. The alterations evolve from the early to the advanced phase mainly in the diffuse subset. In particular, the severe PNS lesions found in advanced lSSc are already present and widely diffuse in early dSSc and the microvascular involvement in early lSSc seems to precede the modification of the PNS in the skin. Thus, an early therapeutic approach can be useful to reduce the progression of PNS and skin damage in SSc patients.


Assuntos
Doenças do Sistema Nervoso Periférico/etiologia , Escleroderma Sistêmico/complicações , Pele/inervação , Adulto , Biópsia , Progressão da Doença , Feminino , Humanos , Masculino , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Doenças do Sistema Nervoso Periférico/patologia , Esclerodermia Difusa/etiologia , Esclerodermia Difusa/patologia , Esclerodermia Limitada/etiologia , Esclerodermia Limitada/patologia , Escleroderma Sistêmico/patologia , Pele/ultraestrutura
15.
J Chem Phys ; 120(8): 3648-56, 2004 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-15268527

RESUMO

Extensive ab initio calculations at the MP2/6-31G* level have been carried out to sample the energy surface for the interactions of the benzene dimers. This database has been used to parameterize two anisotropic single-site models, meant to be used as building blocks in hybrid models of complex, liquid crystal forming molecules. A quadrupolar Gay-Berne (GBQIII) and an S-function (SF) Corner potentials have been obtained in this way. Their ability to reproduce, qualitatively at least, the phase diagram as well as energetic and structural properties of benzene has been tested with Monte Carlo simulations and compared with previous literature potentials, GBQI [S. Gupta et al., Mol. Phys. 65, 961 (1988)] and GBQII [T. R. Walsh, Mol. Phys. 100, 2867 (2002)]. It turned out that GBQI showed no melting transition in the temperature range explored (100-400 K), while GBQII underwent a phase transition from solid to gas, with no liquid phase. Conversely, both models parameterized on our database of ab initio interaction energies (GBQIII and SF) gave rise to a stable liquid phase. Melting has been observed between 100 and 150 K (GBQIII) and in the range 300-350 K (SF), i.e., substantially below and slightly above the experimental value at ambient pressure, 278 K. The description of the crystal structure of benzene at atmospheric pressure is also in better agreement with experimental data if the SF model is used, while positional correlations in the liquid are better described by the GBQIII potential. The S-function potential is also computationally more convenient. These results could be useful in the semirealistic modeling of more complex molecules.

16.
Appl Microbiol Biotechnol ; 65(3): 344-8, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-14740194

RESUMO

When aluminum (Al) was added to a culture, growth of Rhodotorula glutinis IFO1125 was temporarily arrested, showing longer lag phases, depending on the Al concentrations (50-300 microM) added, but the growth rates were not affected at all. Resistant strains obtained by one round of plate treatment containing Al reverted the resistance level to the wild-type level when cultivated without Al. Repeated Al treatments, however, induced heritable and stable Al resistance, the level of which was increased up to 4,000 microM by stepwise increments in Al concentrations. Thus, the heritable Al resistance adaptively acquired was due neither to adaptation nor to mutation, but to a mechanism which has yet to be studied. Heritable Al resistance seemed to release the Al inhibition of magnesium uptake.


Assuntos
Compostos de Alumínio/farmacologia , Cloretos/farmacologia , Farmacorresistência Fúngica , Rhodotorula/efeitos dos fármacos , Adaptação Fisiológica , Cloreto de Alumínio , Meios de Cultura , Magnésio/metabolismo , Mutação , Rhodotorula/genética , Rhodotorula/crescimento & desenvolvimento
17.
J Cell Physiol ; 198(1): 1-11, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14584038

RESUMO

We have previously shown that sphingosine 1-phosphate (S1P) can induce intracellular Ca(2+) mobilization and cell contraction in C2C12 myoblasts and that the two phenomena are temporally unrelated. Although Ca(2+)-independent mechanisms of cell contraction have been the focus of numerous studies on Ca(2+) sensitization of smooth muscle, comparatively less studies have focused on the role that these mechanisms play in the regulation of skeletal muscle contractility. Phosphorylation and activation of myosin by Rho-dependent kinase mediate most of Ca(2+)-independent contractile responses. In the present study, we examined the potential role of Rho/Rho-kinase cascade activation in S1P-induced C2C12 cell contraction. First, we showed that depletion of Ca(2+), by pre-treatment with BAPTA, did not affect S1P-induced myoblastic contractility, whereas it abolished S1P-induced Ca(2+) transients. These results correlated with the absence of troponin C and with the immature cytoskeletal organization of these cells. Experimental evidence demonstrating the involvement of Rho pathway in S1P-stimulated myoblast contraction included: the activation/translocation of RhoA to the membrane in response to agonist-stimulation in cells depleted of Ca(2+) and the inhibition of dynamic changes of the actin cytoskeleton in cells where Rho functions had been inhibited either by overexpression of RhoGDI, a physiological inhibitor of GDP dissociation from Rho proteins, or by pretreatment with Y-27632, a specific Rho kinase inhibitor. Contribution of protein kinase C in this cytoskeletal rearrangement was also evaluated. However, the pretreatment with Gö6976 or rottlerin, specific inhibitors of PKC alpha and PKC delta, respectively, failed to inhibit the agonist-induced myoblastic contraction. Single particle tracking of G-actin fluorescent probe was performed to statistically evaluate actin cytoskeletal dynamics in response to S1P. Stimulation with S1P was also able to increase the phosphorylation level of myosin light chain II. In conclusion, our results strongly suggest that Ca(2+)-independent/Rho-Rho kinase-dependent pathways may exert an important role in S1P-induced myoblastic cell contraction.


Assuntos
Cálcio/metabolismo , Diferenciação Celular/fisiologia , Lisofosfolipídeos , Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/metabolismo , Esfingosina/análogos & derivados , Esfingosina/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Actinas/metabolismo , Animais , Fracionamento Celular , Células Cultivadas , Citoesqueleto/metabolismo , Corantes Fluorescentes/metabolismo , Humanos , Camundongos , Microscopia de Força Atômica , Fibras Musculares Esqueléticas/citologia , Toxina Pertussis/metabolismo , Proteína Quinase C/metabolismo , Troponina C/metabolismo
18.
Reumatismo ; 56(4): 247-52, 2004.
Artigo em Italiano | MEDLINE | ID: mdl-15643479

RESUMO

OBJECTIVES: PNS is involved in Systemic Sclerosis (SSc) since the earliest phases. Our aim is to perform an ultrastructural study on skin PNS fibers in SSc. METHODS: Skin biopsies were taken from forearms of 8 patients affected by limited SSc (lSSc) and 3 controls and processed for transmission electron microscopy (TEM). The semithin sections (2 mm) were observed at light microscope and optical fields were chosen for ultrathin sections (1 mm) preparation and TEM examination. RESULTS: In lSSc skin, in the semithin sections, damaged areas are close to apparently spared areas. At TEM, in early lSSc patients, signs of inflammation and damaged microvessels are visible in derma. PNS fibers are no damaged. In advanced lSSc, fibrosis prevails on inflammation, and slight ultrastructural alterations of PNS fibers are evident in papillar derma. CONCLUSIONS: PNS lesions are different in severity in lSSc according to the disease duration, resulting more severe in advanced than in early phase.


Assuntos
Fibras Nervosas/ultraestrutura , Sistema Nervoso Periférico/fisiopatologia , Esclerodermia Limitada/fisiopatologia , Pele/inervação , Biópsia , Distribuição de Qui-Quadrado , Interpretação Estatística de Dados , Feminino , Fibrose , Técnicas de Preparação Histocitológica , Humanos , Masculino , Microcirculação , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade , Esclerodermia Limitada/patologia , Pele/patologia , Fatores de Tempo
19.
Cells Tissues Organs ; 178(3): 129-38, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15655330

RESUMO

Sphingosine-1-phosphate (S1P) is a lipid mediator, which affects many essential processes such as cell proliferation, differentiation and contraction in many cell types. We have previously demonstrated that the lipid mediator elicits Ca(2+) transients in a myoblastic cell line (C2C12) by interacting with its specific receptors (S1PR(s)). In the present study, we wanted to correlate the Ca(2+) response with activation of myoblastic cell contractility. C2C12 cells were first investigated for the expression and cellular organization of cytoskeletal proteins by immunoconfocal microscopy. We found that myoblasts exhibited a quite immature cytoskeleton, with filamentous actin dispersed as a web-like structure within the cytoplasm. To evaluate intracellular Ca(2+) mobilization, the cells were loaded with a fluorescent Ca(2+) indicator (Fluo-3), stimulated with S1P and simultaneously observed with differential interference contrast and fluorescence optics. Exogenous S1P-induced myoblastic cell contraction was temporally unrelated to S1P-induced intracellular Ca(2+) increase; cell contraction occurred within 5-8 s from stimulation, whereas intracellular Ca(2+) increase was evident only after 15-25 s. To support the Ca(2+) independence of myoblastic cell contraction, the cells were pretreated with a Ca(2+) chelator, BAPTA/AM, prior to stimulation with S1P. In these experimental conditions, the myoblasts were still able to contract, whereas the S1P-induced Ca(2+) transients were completely abolished. On the contrary, when C2C12 cells were induced to differentiate into skeletal myotubes, they responded to S1P with a rapid cell contraction concurrent with an increase in the intracellular Ca(2+). These data suggest that Ca(2+)-independent mechanism of cell contraction may be replaced by Ca(2+)-dependent ones during skeletal muscle differentiation.


Assuntos
Sinalização do Cálcio/efeitos dos fármacos , Cálcio/metabolismo , Ácido Egtázico/análogos & derivados , Lisofosfolipídeos/farmacologia , Contração Muscular/efeitos dos fármacos , Esfingosina/análogos & derivados , Esfingosina/farmacologia , Actinas/efeitos dos fármacos , Animais , Linhagem Celular , Tamanho Celular/efeitos dos fármacos , Quelantes/farmacologia , Citoesqueleto/efeitos dos fármacos , Ácido Egtázico/farmacologia , Técnica Indireta de Fluorescência para Anticorpo , Corantes Fluorescentes , Processamento de Imagem Assistida por Computador , Cinética , Camundongos , Microscopia Confocal , Mioblastos
20.
Plant Cell Environ ; 26(4): 497-503, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12817604

RESUMO

A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 degrees C, a relative humidity of 18% and an irradiance of 260 W m-2. Mean leaf temperatures increased by 0.9-1.0 degrees C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 degrees C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 degrees C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s-1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection.


Assuntos
Ar Condicionado , Gravitação , Folhas de Planta/fisiologia , Voo Espacial , Temperatura , Ausência de Peso , Convecção , Ambiente Controlado , Hordeum , Ipomoea batatas , Termografia , Fatores de Tempo
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