RESUMO
Multifractal properties of diurnal temperature range (DTR) have been analyzed in this work, using validated data of maximum and minimum temperature from 197 weather stations in Southern Spain (Andalusia region). DTR is a crucial factor to characterize the regional climate, providing more information than the average daily temperature. Apart from climate change studies, one of the most important applications of DTR in Agrometeorology is as an input variable in the solar radiation or reference evapotranspiration estimation models based on the temperature. With the aim of obtaining a detailed information for different time scales, different multifractal approaches have been applied. Different quality control methods such as range/limits or persistence tests were previously applied in order to detect incorrect and anomalous values, being discarded in the subsequent analysis. The DTR scaling of moments has been analyzed and the moment scaling exponent function K(q) has been obtained, finding some differences between weather stations. In addition, multifractal dimension (D1) and multifractal degree (MD) were also estimated, revealing differences at coastal and inland locations that show heterogeneity across the region, including its multifractal nature and its invariance for a range of scales. The nonlinear characterization carried out in this work improves the understanding of DTR as an indicator of climate changes, and it can have a very positive impact on the calibration of regional models for estimating solar radiation or reference evapotranspiration based on the temperature. This multifractal characterization can be used to group stations with similar nonlinear dynamics, regardless of their geographical features, in such a way that more accurate coefficients than conventional ones are used.
RESUMO
High- or moderate-intensity endurance training leads to mitochondrial biogenesis via the peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α)/mitochondrial transcription factor A (Tfam) signaling pathway. Although this pathway is stimulated during acute exercise, the relationship between its activity and the intensity of the exercise has not been characterized. In animal studies, individualized running speeds have not previously been assessed. Here, we sought to determine whether this pathway was modulated after a bout of exhaustive exercise at different relative intensities (at and over critical speed (CS)). Our starting hypotheses were that (i) exercise-induced overexpression of PGC-1α in skeletal muscle falls at intensities above CS, and (ii) transcriptional activity of the mitochondrial biogenesis signaling cascade is intensity-sensitive at and above CS. To test these hypothesis, male Friend Virus B-Type mice were divided into a control group and three exercise groups (exercising at CS, peak velocity (vPeak) and 150 % CS, respectively). mRNA expression levels for genes involved in mitochondrial biogenesis signaling were analyzed in the quadriceps muscle. PGC-1α was overexpressed at all exercise intensities. We also identified that, PGC-1α mRNA expression was negatively correlated with exercise intensity and blood lactate levels but not with maximal oxygen uptake, vPeak, or CS. Expression of the PGC-1α co-activator peroxisome proliferator-activated receptor ß was negatively correlated with the exercise intensity. In contrast, expression levels of Tfam were dissociated from exercise intensity. Our data indicate that at the intensities used in endurance training, the expression of mitochondrial biogenesis genes is finely modulated by the relative intensity of exhaustive exercise.
Assuntos
Vias Biossintéticas/genética , Mitocôndrias Musculares/genética , Transcrição Gênica/genética , Animais , Proteínas de Ligação a DNA/genética , Feminino , Proteínas de Grupo de Alta Mobilidade/genética , Masculino , Camundongos , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Oxigênio/metabolismo , PPAR beta/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Condicionamento Físico Animal/métodos , RNA Mensageiro/genética , Fatores de Transcrição/genéticaRESUMO
University students have to handle crucial challenges for their future lives, such as succeeding in academic studies and finding attachment figures. These processes could potentially involve their well-being and mental health, with possible sociocultural differences based on the country of study. In order to explore such potential differences, a cross-sectional, multi-center survey was performed involving students from the University of Torino (Italy), Sevilla (Spain), and Lusòfona (Portugal). The survey, conducted from May to November 2023, investigated students' demographic and educational details, socioeconomic status, social support, mental health, academic environment, perceived COVID-19 pandemic impact, and future plans. Demographic profiles showed a predominance of female participants and straight sexual orientation, followed by bisexuality. Italian students showed the lowest levels of mental well-being and the highest rates of mental problems (anxiety and depression) and suicidal risk across the three countries despite the relatively similar profiles of social support. The prevalence of the students' confidence in their professional future is higher in Spain than in Italy and Portugal. This study provides a comprehensive examination of university students' mental health and well-being in three Southern European countries, addressing the major mental health challenges among university students and offering valuable insights for public health purposes.
Assuntos
COVID-19 , Saúde Mental , Estudantes , Humanos , Feminino , Estudantes/psicologia , COVID-19/epidemiologia , COVID-19/psicologia , Universidades , Masculino , Estudos Transversais , Itália/epidemiologia , Adulto Jovem , Espanha/epidemiologia , Inquéritos e Questionários , Adulto , Portugal/epidemiologia , Depressão/epidemiologia , Depressão/psicologia , Ansiedade/epidemiologia , Ansiedade/psicologia , Adolescente , Apoio Social , SARS-CoV-2/isolamento & purificaçãoRESUMO
Structural and functional effects of exposing murine fibroblasts (NIH 3T3) to therapeutic ultrasound at 1 MHz frequency are described. These bioeffects can be attributed to the formation of free radical species by sonolysis of water. When cavitation occurs, dissociation of water vapor into H atoms and OH radicals is observed; these H atoms and OH radicals combine to form H(2), H(2)O(2), and HO(2). The radicals can chemically modify biomolecules, for example enzymes, DNA, and lipids. Generation of free radicals during exposure to ultrasound with or without encapsulated microbubbles (contrast agents) was studied by use of electron paramagnetic resonance with DMPO spin trapping. Recently the potential for possible use of these microbubbles in gene therapy has been investigated, because of the ability of the stabilized microbubbles to release their content when exposed to ultrasound. Structural changes were studied by Fourier-transform infrared spectroscopy, and induction of possible genotoxic damage by exposure of the cells to therapeutic ultrasound at 1 MHz frequency with our experimental device was verified by use of the cytokinesis-block micronucleus assay.
Assuntos
Espectroscopia de Ressonância de Spin Eletrônica/métodos , Fibroblastos/efeitos dos fármacos , Fibroblastos/efeitos da radiação , Microbolhas , Som , Espectroscopia de Infravermelho com Transformada de Fourier , Terapia por Ultrassom , Animais , Soluções Tampão , Linhagem Celular , Óxidos N-Cíclicos/química , Citocinese/genética , Fibroblastos/citologia , Terapia Genética/métodos , Radical Hidroxila/química , Radical Hidroxila/metabolismo , Camundongos , Microbolhas/efeitos adversos , Testes para Micronúcleos , Células NIH 3T3 , Fosfatos/química , Som/efeitos adversos , Detecção de Spin , Terapia por Ultrassom/efeitos adversosRESUMO
Cardiac allograft vasculopathy (CAV) is an accelerated form of coronary artery disease affecting both intramyocardial and epicardial coronary arteries and is observed in patients during long-term survival after cardiac transplantation. We report a case of CAV complicated with silent transmural myocardial infarction and massive left ventricular thrombus formation associated with silent pericarditis and with ischemic and non-ischemic scar tissue, as detected by cardiac magnetic resonance imaging (CMRI). The authors suggest CMRI as an additional technique along with echocardiography during follow-up of heart transplant recipients. CMRI may contribute to the early identification of areas of myocardial wall abnormalities suggestive of CAV, thus guiding diagnosis and prompt percutaneous treatment.
Assuntos
Cicatriz/complicações , Cicatriz/diagnóstico , Doença da Artéria Coronariana/complicações , Doença da Artéria Coronariana/diagnóstico , Ecocardiografia , Processamento de Imagem Assistida por Computador , Imagem Cinética por Ressonância Magnética , Infarto do Miocárdio/complicações , Infarto do Miocárdio/diagnóstico , Complicações Pós-Operatórias/diagnóstico , Idoso , Cicatriz/terapia , Comorbidade , Doença da Artéria Coronariana/terapia , Diagnóstico Precoce , Ventrículos do Coração , Humanos , Masculino , Infarto do Miocárdio/terapia , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/etiologia , Isquemia Miocárdica/terapia , Pericardite/diagnóstico , Pericardite/etiologia , Pericardite/terapia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/terapia , Prevenção Secundária , Sobreviventes , Trombose/diagnóstico , Trombose/etiologiaRESUMO
We have made a preliminary analysis of the results about the effects on tumoral cell line (lymphoid T cell line Jurkat) induced by UVB radiation (dose of 310 mJ/cm(2)) with and without a vegetable mixture. In the present study, we have used two techniques: Fourier transform infrared spectroscopy (FTIR) and flow cytometry. FTIR spectroscopy has the potential to provide the identification of the vibrational modes of some of the major compounds (lipid, proteins and nucleic acids) without being invasive in the biomaterials. The second technique has allowed us to perform measurements of cytotoxicity and to assess the percentage of apoptosis. We already studied the induction of apoptotic process in the same cell line by UVB radiation; in particular, we looked for correspondences and correlations between FTIR spectroscopy and flow cytometry data finding three highly probable spectroscopic markers of apoptosis (Pozzi et al. in Radiat Res 168:698-705, 2007). In the present work, the results have shown significant changes in the absorbance and spectral pattern in the wavenumber protein and nucleic acids regions after the treatments.
Assuntos
Apoptose/efeitos dos fármacos , Células Jurkat/efeitos da radiação , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Raios Ultravioleta , Apoptose/fisiologia , Células Cultivadas , Citometria de Fluxo/métodos , Humanos , Espectrofotometria Infravermelho/métodosRESUMO
BACKGROUND: Type 5 phosphodiesterase (PDE5) expression in the normal and pathological prostate is controversial. OBJECTIVES: This study aimed at identifying the cell type/s, if any, expressing PDE5 in human healthy or pathological prostate sections in order to further validate the rationale of PDE5 inhibitor (PDE5i) treatment of benign prostatic hyperplasia (BPH) and their safety in the treatment of erectile dysfunction following prostate cancer (PCa) surgery. MATERIALS AND METHODS: By immunohistochemical analysis, we studied PDE5 expression in tissue microarrays containing sections obtained from healthy, BPH, and PCa samples. RESULTS: Our results showed that PDE5 is barely expressed in the epithelial or stromal compartment of normal human prostates, but it is highly expressed in the stromal compartment of BPH sections. We also found that a low but significant number of PCa samples (22%) expressed PDE5 in the epithelial cancer cells but not in stromal cells and that such expression was not correlated with the tumor aggressiveness, according to their Gleason score. DISCUSSION AND CONCLUSION: PDE5 overexpression in the stromal compartment of BPH samples supports the rationale of PDE5 as a target in lower urinary tract symptoms of BPH. PDE5 expression in a significant percentage of PCa samples but the lack of correlation with the Gleason score suggests that this enzyme is not correlated with tumor aggressiveness; however, a role of PDE5 in the minimal residual disease of PCa cannot be excluded.
Assuntos
Adenocarcinoma/enzimologia , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/biossíntese , Próstata/enzimologia , Hiperplasia Prostática/enzimologia , Neoplasias da Próstata/enzimologia , Adenocarcinoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/análise , Humanos , Masculino , Pessoa de Meia-Idade , Próstata/patologia , Hiperplasia Prostática/patologia , Neoplasias da Próstata/patologia , Adulto JovemRESUMO
AIMS/HYPOTHESIS: Due to their ability to regulate various signalling pathways (cytokines, hormones, growth factors), the suppressor of cytokine signalling (SOCS) proteins are thought to be promising therapeutic targets for metabolic and inflammatory disorders. Hence, their role in vivo has to be precisely determined. METHODS: We generated transgenic mice constitutively producing SOCS-3 in skeletal muscle to define whether the sole abundance of SOCS-3 is sufficient to induce metabolic disorders and whether SOCS-3 is implicated in physiological roles distinct from metabolism. RESULTS: We demonstrate here that chronic expression of SOCS-3 in skeletal muscle leads to overweight in mice and worsening of high-fat diet-induced systemic insulin resistance. Counter-intuitively, insulin sensitivity in muscle of transgenic mice appears to be unaltered. However, following constitutive SOCS-3 production, several genes had deregulated expression, among them other members of the SOCS family. This could maintain the insulin signal into skeletal muscle. Interestingly, we found that SOCS-3 interacts with calcineurin, which has been implicated in muscle contractility. In Socs-3 transgenic muscle, this leads to delocalisation of calcineurin to the fibre periphery. Relevant to this finding, Socs-3 transgenic animals had dilatation of the sarcoplasmic reticulum associated with swollen mitochondria and decreased voluntary activity. CONCLUSIONS/INTERPRETATION: Our results show that constitutive SOCS-3 production in skeletal muscle is not in itself sufficient to induce the establishment of metabolic disorders such as diabetes. In contrast, we reveal a novel role of SOCS-3, which appears to be important for muscle integrity and locomotor activity.
Assuntos
Atividade Motora/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Sobrepeso/genética , Proteínas Supressoras da Sinalização de Citocina/fisiologia , Animais , Calcineurina/metabolismo , Calorimetria , Técnicas In Vitro , Insulina/metabolismo , Camundongos , Camundongos Transgênicos , Atividade Motora/genética , Músculo Esquelético/citologia , Análise de Sequência com Séries de Oligonucleotídeos , Ligação Proteica , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Proteína 3 Supressora da Sinalização de Citocinas , Proteínas Supressoras da Sinalização de Citocina/genética , Proteínas Supressoras da Sinalização de Citocina/metabolismoRESUMO
We reported recently that peroxisome proliferator-activated receptor beta (PPARbeta) activation promotes a calcineurin-dependent exercise-like remodelling characterised by increased numbers of oxidative fibres and capillaries. As physical exercise also induces myonuclear accretion, we investigated whether PPARbeta activation alters myonuclear density. Transgenic muscle-specific PPARbeta over-expression induced 14% increase of myonuclear density. Pharmacological PPARbeta activation promoted rapid and massive myonuclear accretion (20% increase after 48 h), which is dependent upon calcineurin/nuclear factor of activated T cells signalling pathway. In vivo bromodeoxyuridine labelling and proliferating cell nuclear antigen immunodetection revealed that PPARbeta activation did not promote cell proliferation, suggesting that the PPARbeta-promoted myonuclear accretion involves fusion of pre-existing muscle precursor cells to myofibres rather than cell division. Finally, we showed that in skeletal muscle, ageing led to a down-regulation of PPARbeta accompanied by decrease of both oxidative fibre number and myonuclear density. PPARbeta pharmacological activation counteracts, at least in part, the ageing-driven muscle remodelling.
Assuntos
Envelhecimento/fisiologia , Núcleo Celular/fisiologia , Músculo Esquelético/citologia , PPAR beta/fisiologia , Envelhecimento/efeitos dos fármacos , Envelhecimento/patologia , Animais , Calcineurina/metabolismo , Inibidores de Calcineurina , Divisão Celular/efeitos dos fármacos , Fusão Celular , Citrato (si)-Sintase/metabolismo , Ciclosporina/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Camundongos Transgênicos , Fibras Musculares de Contração Rápida/citologia , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Fatores de Transcrição NFATC/metabolismo , PPAR beta/agonistas , Antígeno Nuclear de Célula em Proliferação/metabolismo , Células Satélites de Músculo Esquelético/citologia , Células Satélites de Músculo Esquelético/efeitos dos fármacos , Succinato Desidrogenase/metabolismo , Tiazóis/farmacologiaRESUMO
Adipose tissue development takes place primarily around birth but adipose cell number can increase throughout life in response to nutritional changes. At the molecular level, adipogenesis is the result of transcriptional remodeling that leads to activation of a considerable number of genes. Several transcription factors act cooperatively and sequentially in this process. This article attempts to review the roles of peroxisome proliferator-activated receptors gamma and delta in the control of preadipocyte proliferation and differentiation during adipose tissue development or during the adaptive response of adipose tissue mass to high-fat feeding.
Assuntos
Adipócitos/metabolismo , Adipócitos/fisiologia , Tecido Adiposo/metabolismo , Receptores Citoplasmáticos e Nucleares/fisiologia , Transdução de Sinais/fisiologia , Fatores de Transcrição/fisiologia , Animais , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Diferenciação Celular , Células Cultivadas , Ácidos Graxos/metabolismo , Humanos , Insulina/metabolismo , Transcrição GênicaRESUMO
Adequate treatment of panfacial injuries often requires tracheostomy or alternating intubation through the nose and the mouth to keep the field free during the operation. Altemir's submental technique is an attractive option in these patients. We used the method with a slight modification in 107 operations in our unit to treat panfacial injuries. We had a low rate of complications and no increased operative time.
Assuntos
Traumatismos Faciais/cirurgia , Intubação Intratraqueal/métodos , Dissecação/métodos , Ossos Faciais/lesões , Ossos Faciais/cirurgia , Humanos , Intubação Intratraqueal/instrumentação , Mandíbula , Fraturas Maxilares/cirurgia , Soalho Bucal/cirurgia , Fraturas Cranianas/cirurgia , Resultado do TratamentoRESUMO
e realizó un analisis de la tasa de cesáreas en dos maternidades públicas de referencia de Uruguay (Hospital de Clínicas y Centro Hospitalario Pereira Rossell) utilizando la clasificación de Robson para compararlas entre sí, mediante un estudio observacional, descriptivo, retrospectivo y transversal en un periodo de 10 años y 10 meses (2009-2019). Se analizaron 85.526 nacimientos (7.685 (8,9%) en el Clínicas vs 77.841 (91.1%) Pereira Rossell). El porcentaje de cesáreas por año en el Clínicas fue 49,2% ± 5 vs 29,3% ± 3 en Pereira Rossell. Los grupos de Robson más prevalentes fueron 1, 5A y 10 en el Clínicas vs 3, 1 y 5A en Pereira Rossell. En ambos centros los grupos con mayor contribución relativa a la tasa global de cesáreas fueron: 5A, 10 y 1. Ambos centros presentan un aumento en la tasa de cesárea en la última década, pese a que se asisten poblaciones dispares entre cada uno de ellos. Se debe seguir buscando estrategias que ayuden a reducir la tasa de cesáreas principalmente en pacientes sin cesáreas anteriores o con una única cesárea previa, en caso de no presentan contraindicaciones para el parto vaginal.(AU)
An analysis of the caesarean section rate was carried out in two reference public maternity wards in Uruguay (Hospital de Clínicas and Centro Hospitalario Pereira Rossell) using Robson's classification to compare them with each other, through an observational, descriptive, retrospective and cross-sectional study in a period 10 years and 10 months (2009-2019). 85,526 births were analyzed (7,685 (8.9%) in the Clinics vs 77,841 (91.1%) Pereira Rossell). The percentage of caesarean sections per year in the Clinics was 49.2% ± 5 vs 29.3% ± 3 in Pereira Rossell. The most prevalent Robson groups were 1, 5A and 10 in the Clinicas vs 3, 1 and 5A in Pereira Rossell. In both centers, the groups with the highest relative contribution to the overall rate of cesarean sections were: 5A, 10 and 1. Both centers show an increase in the rate of cesarean section in the last decade, despite the fact that different populations are attended between each of them. Strategies should continue to be sought to help reduce the rate of cesarean sections, mainly in patients without previous cesarean sections or with a single previous cesarean section, if they do not present contraindications for vaginal delivery. (AU)
Foi realizada análise da taxa de cesárea em duas maternidades públicas de referência do Uruguai (Hospital de Clínicas e Centro Hospitalario Pereira Rossell), utilizando a classificação de Robson para compará-las, por meio de estudo observacional, descritivo, retrospectivo e transversal. em um período de 10 anos e 10 meses (2009-2019). Foram analisados 85.526 partos (7.685 (8,9%) nas Clínicas vs 77.841 (91,1%) Pereira Rossell). A porcentagem de cesarianas por ano nas Clínicas foi de 49,2% ± 5 vs 29,3% ± 3 em Pereira Rossell. Os grupos de Robson mais prevalentes foram 1, 5A e 10 nas Clínicas vs 3, 1 e 5A em Pereira Rossell. Em ambos os centros, os grupos com maior contribuição relativa para a taxa global de cesárea foram: 5A, 10 e 1. Ambos os centros apresentam aumento da taxa de cesárea na última década, apesar de diferentes populações serem atendidas entre cada um deles. Estratégias devem continuar a ser buscadas para ajudar a reduzir a taxa de cesárea, principalmente em pacientes sem cesárea anterior ou com cesárea única, se não apresentarem contra-indicações para parto normal. (AU)
Assuntos
Uruguai/epidemiologia , Cesárea/classificação , PrevalênciaRESUMO
The adipose conversion of ob 17 preadipose cells can be irreversibly blocked when prostaglandin F2alpha is included post-confluence for a minimum of 24 h in insulin-containing media. Prostaglandins E1 and E2 are inactive. The lack of adipose conversion is accompanied by the maintenance of a fusiform cell shape, by a slow increase in cell number and by a potent rise in de novo prostaglandin synthesis; it is paralleled by the absence of the characteristic phenotypes of adipose conversion. The multiple effects of prostaglandin F2alpha are dose-dependent, with half-maximal concentrations ranging from 10 to 40 nM. The absence of differentiation and the high rate of prostaglandin synthesis in the presence of prostaglandin F2alpha are likely a consequence of a sustained growth, as also observed with other growth-promoting agents (bovine retinal extract and cat serum). Indomethacin, while suppressing endogenous prostaglandin synthesis, is unable to reverse the long-term and multiple effects of prostaglandin F2alpha. Although adipose conversion normally follows a decrease in prostaglandin production (R. Négrel and G. Ailhaud, Biochem. Biophys. Res. Commun. (1981) 98, 768-777), these results indicate that both events can be dissociated.
Assuntos
Tecido Adiposo/citologia , Prostaglandinas F/farmacologia , Prostaglandinas/biossíntese , Tecido Adiposo/efeitos dos fármacos , Animais , Diferenciação Celular/efeitos dos fármacos , Coenzima A Ligases/metabolismo , Dinoprosta , Dinoprostona , Relação Dose-Resposta a Droga , Glicerolfosfato Desidrogenase/metabolismo , Indometacina/farmacologia , L-Lactato Desidrogenase/metabolismo , Masculino , Camundongos , Camundongos Obesos , Prostaglandinas E/farmacologiaRESUMO
Binding of human lipoproteins to cultured mouse Ob17 preadipose and adipose cells was studied, using labeled VLDL, LDL and apoprotein E-free HDL. In each case, saturation curves were obtained, yielding linear Scatchard plots. The Kd values were found to be respectively 6.4, 31 and 24 micrograms/ml for VLDL, LDL and apoprotein E-free HDL, whereas the maximal numbers of binding sites per cell were 4.2 X 10(4), 1.5 X 10(4) and 2.5 X 10(5). The binding of 125I-LDL was competitively inhibited by LDL greater than VLDL greater than total HDL; human LDL and mouse LDL were equipotent in competition assays. Methylated LDL and apoprotein E-free HDL were not competitors. In contrast, the binding of 125I-apoprotein E-free HDL was competitively inhibited by apoprotein E-free HDL greater than total HDL and the binding of 125I-HDL3 by mouse HDL. Thus, mouse adipose cells possess distinct apoprotein B, E and apoprotein E-free HDL binding sites which can recognize heterologous or homologous lipoproteins. The cell surface receptor of LDL in mouse preadipose cells shows similarities with that described for human fibroblasts, since: (1) the LDL binding initiated the process of internalization and degradation of the apoprotein B and apoprotein E-containing lipoproteins; (2) receptor-mediated uptake of cholesterol LDL led to a parallel but incomplete decrease in the [14C]acetate incorporation into cholesterol and in the activity of HMG-CoA reductase. Growing (undifferentiated) or growth-arrested cells (differentiated or not) showed no significant changes in the Kd values for lipoprotein binding. In contrast, the maximal number of binding sites correlated with the proliferative state of the cells and was independent of cell differentiation. The results are discussed with respect to cholesterol accumulation in adipose cells.
Assuntos
Tecido Adiposo/metabolismo , Colesterol/biossíntese , Lipoproteínas/metabolismo , Animais , Apolipoproteínas/metabolismo , Sítios de Ligação , Ligação Competitiva , Células Cultivadas , Humanos , Cinética , Lipoproteínas HDL/metabolismo , Lipoproteínas LDL/metabolismo , Lipoproteínas VLDL/metabolismo , CamundongosRESUMO
Binding of high-density lipoproteins to cultured mouse Ob1771 adipose cells was studied, using labeled human HDL3, mouse HDL and apolipoprotein AI- or AII-containing liposomes. In each case, saturation curves were obtained, yielding linear Scatchard plots. The Kd values were found to be respectively 18, 42, 30 and 3.4 micrograms/ml, whereas the maximal binding capacities were found to be 160, 100, 90 and 21 ng/mg of cell protein. Apoprotein AI not inserted into liposomes did not bind. The binding of 125I-HDL3 was competitively inhibited by apolipoprotein AI-containing liposomes greater than mouse HDL greater than HDL3. The binding of 125I-labeled apolipoprotein AI- and 125I-labeled apolipoprotein AII-containing liposomes was competitively inhibited by HDL3, apolipoprotein AI- and apolipoprotein AII-containing liposomes. Dimyristoylphosphatidylcholine liposomes containing or not cholesterol did not interfere with the binding of labeled HDL3 or apolipoprotein-containing liposomes. Binding studies on crude membranes of Ob1771 adipose cells revealed the presence of intracellular binding sites for LDL and HDL3. Thus, adipose cells have specific binding sites for apolipoprotein E-free HDL and apolipoprotein AI (or AII) is the ligand for these binding sites. Long-term exposure of adipose cells to LDL cholesterol as a function of LDL concentration led to an accumulation of cellular unesterified cholesterol. This process was saturable and reversible as a function of time and concentration by exposure to HDL3 or apolipoprotein AI-containing liposomes, whereas apolipoprotein AII-containing liposomes did not promote any cholesterol efflux. Since long-term exposure of adipose cells to LDL and HDL3 did not affect the number of apolipoprotein B,E receptors and apolipoprotein E-free binding sites, respectively, it appears that adipose cells do not show efficient cholesterol homeostasis and thus could accumulate or mobilize unesterified cholesterol.
Assuntos
Tecido Adiposo/metabolismo , Colesterol/metabolismo , Lipoproteínas HDL/metabolismo , Animais , Apolipoproteínas A/metabolismo , Apolipoproteínas B/metabolismo , Apolipoproteínas E/metabolismo , Ligação Competitiva , Diferenciação Celular , Membrana Celular/metabolismo , Células Cultivadas , Cinética , Lipoproteínas LDL/metabolismo , Camundongos , Receptores de Superfície Celular/metabolismo , TemperaturaRESUMO
Conversion of ob 17 preadipocytes to mature adipose cells is accelerated by addition of clofenapate or of indomethacin, in either the absence or presence of insulin. General stimulation of triacylglycerol-pathway enzymes is observed, as well as dramatic increase in endogenous fatty-acid synthesis. This increase is a function of drug concentration and exposure time. In contrast to indomethacin, the continuous presence of clofenapate after the cells reached confluence was required to observe the effects on adipose conversion. Growth of ob 17 fibroblasts in the presence of 5-bromo-2'-deoxyuridine normally prevents their differentiation to adipose cells. Addition of either clofenapate or indomethacin to these cells at confluence overrides this block. The effects of hypolipidemic drugs such as clofenapate observed on a long-term basis in vitro are consistent with the results of studies on adipose tissue in vivo.
Assuntos
Tecido Adiposo/fisiologia , Butiratos/farmacologia , Clofenapato/farmacologia , Indometacina/farmacologia , Lipídeos/biossíntese , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/ultraestrutura , Animais , Bromodesoxiuridina/farmacologia , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Insulina/farmacologia , Camundongos , Camundongos Obesos , Microscopia Eletrônica , Triglicerídeos/biossínteseRESUMO
Peroxisome proliferator-activated receptors (PPAR) mediate some of the transcriptional effects of fatty acids and control many physiological functions, especially in the field of development and metabolism. Three isotypes are known, alpha, gamma, and B/delta. Roles of PPAR alpha and PPARgamma are now quite well-known, particularly since their pharmacologic ligands have been marketed, respectively the lipid-normalizing class of fibrates and the antidiabetic class of thiazolidinediones (glitazones). However, functions of PPARdelta are uncompletely known to date, but some recent data enlight its role in the regulation of fatty acid oxidation in several tissues, such as skeletal muscle and adipose tissue. Overexpression of PPARdelta using a transgenic murine model promotes an increase of muscle oxidative capability. This is accompanied by a redistribution of fatty acid flux, redirected from adipose tissue towards skeletal muscle. Finally, adipose mass is reduced, due to a decreased adipocyte size. These data strongly suggest that PPARdelta play a major role in the metabolic adaptations to western diet characterized by an excessive amount of saturated fat. Considering the metabolic properties of the two other PPAR isotypes, alpha and gamma, it is likely that the three PPAR isotypes have complementary effects in the pathophysiology of obesity and metabolic syndrome. Future therapeutical perspectives in this field should consider combined treatment, adding delta agonists (for all that their safety will be established) to the already available alpha and gamma agonists.
Assuntos
PPAR delta/fisiologia , Animais , Arteriosclerose/genética , Regulação da Expressão Gênica , Homeostase , Humanos , Metabolismo dos Lipídeos , Modelos Biológicos , PPAR delta/genética , Transcrição GênicaRESUMO
Adipose differentiation is a multistep process with the following sequence: adipoblasts --> preadipocytes --> adipocytes. Adipogenic agents are only involved in the terminal differentiation of preadipocytes to adipocytes by means of circulating hormones (growth hormone, glucocorticoids, or triiodothyronine) and locally produced hormones (prostacyclin). Fatty acids also behave as hormones and act as transcriptional regulators of lipid-related genes. Once differentiated, adipocytes become secretory cells able to synthetize and release an impressive number of peptide and nonpeptide compounds, suggesting a potential link between excess of adipose tissue mass and various physiopathphysiologic consequences.
RESUMO
The hormonal regulation of the human urokinase type plasminogen activator (uPA) gene has been studied by introducing into mouse and rat Sertoli cell primary cultures a recombinant plasmid, in which the transcription regulatory elements of the cloned human uPA gene drive the expression of the bacterial chloramphenicol-acetyl-transferase gene. It was found to be expressed and regulated by FSH and (Bu)2cAMP in the mouse cells only, in agreement with data on the expression of the endogenous gene in rat and mouse gonads. The stimulation of transcription by FSH was evident in cultures from 13-day-old but not from 18-day-old mice, even though (Bu)2cAMP induction could be observed at both ages. Phorbol-myristate acetate was found to activate the human uPA promoter in Sertoli cell cultures from mice of both ages, even though the effect was less evident in cultures of 18-day-old animals. Deletion analysis of the human uPA 5'-flanking region showed that the distal enhancer element is not needed for (Bu)2cAMP induction, and that at least two promoter regions are involved in (Bu)2cAMP induced transcription. One of these cAMP responsive regions lies between nucleotides -72 and -29 from the CAP site. The sequence of this region would suggest the binding of transcription factor AP-2, a cell-specific mediator of both cAMP and phorbol esters action on gene expression. However, these sequences do not mediate phorbol ester activation of human uPA promoter in mouse Sertoli cells.
Assuntos
AMP Cíclico/farmacologia , Hormônio Foliculoestimulante/farmacologia , Ativadores de Plasminogênio/genética , Regiões Promotoras Genéticas/genética , Células de Sertoli/metabolismo , Transcrição Gênica/efeitos dos fármacos , Ativador de Plasminogênio Tipo Uroquinase/genética , Animais , Sequência de Bases , Células Cultivadas , AMP Cíclico/análogos & derivados , Fibrinolíticos/metabolismo , Masculino , Camundongos , Dados de Sequência Molecular , Ésteres de Forbol/farmacologia , Plasmídeos , Ativadores de Plasminogênio/metabolismo , Ativadores de Plasminogênio/fisiologia , Células de Sertoli/efeitos dos fármacos , Transfecção , Ativador de Plasminogênio Tipo Uroquinase/metabolismo , Ativador de Plasminogênio Tipo Uroquinase/fisiologiaRESUMO
Transcription factors which recognize both the SV40 promoter and the proximal promoter region of the human urokinase-type plasminogen activator (h-uPA) gene are present in nuclear extracts from primary cultures of mouse Sertoli cells; prolonged (more than 12 h) (Bu)2cAMP stimulation of Sertoli cells induces the formation of different specific DNA-protein complexes. A discrete region in the h-uPA promoter, between -54 and -42, is essential for the formation of the cAMP-induced DNA-protein complexes. Mutation of the sequence between -54 and -42 abolishes the response to cAMP of the proximal h-uPA promoter in Sertoli cells. A protein, recognizing a sequence centered around the GC-box present between -48 and -43, is detected by Southwestern analysis, and it is clearly induced by (Bu)2cAMP stimulation. Interaction between this protein and a second factor, recognizing a purine-rich sequence between -53 and -46, partially overlapping the GC-box, is needed for the formation of the cAMP-induced DNA-protein complexes. A preformed complex between the cAMP-induced GC-box-binding factor and the second factor can be detected using nondenaturing conditions during Southwestern analysis.