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1.
J Chem Phys ; 143(12): 124508, 2015 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-26429025

RESUMO

The progress in high performance computing we are witnessing today offers the possibility of accurate electron density calculations of systems in realistic physico-chemical conditions. In this paper, we present a strategy aimed at performing a first-principle computation of the low energy part of the X-ray Absorption Spectroscopy (XAS) spectrum based on the density functional theory calculation of the electronic potential. To test its effectiveness, we apply the method to the computation of the X-ray absorption near edge structure part of the XAS spectrum in the paradigmatic, but simple case of Cu(2+) in water. In order to keep into account the effect of the metal site structure fluctuations in determining the experimental signal, the theoretical spectrum is evaluated as the average over the computed spectra of a statistically significant number of simulated metal site configurations. The comparison of experimental data with theoretical calculations suggests that Cu(2+) lives preferentially in a square-pyramidal geometry. The remarkable success of this approach in the interpretation of XAS data makes us optimistic about the possibility of extending the computational strategy we have outlined to the more interesting case of molecules of biological relevance bound to transition metal ions.

2.
Horm Metab Res ; 46(4): 294-8, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24505030

RESUMO

One possible result of fine-needle aspiration (FNA) of thyroid nodules is "nondiagnostic" cytology. Consensus exists in these cases to repeat FNA guided by ultrasonography (US), but the result obtained may continue to be nondiagnostic. The objective of this study was to evaluate predictive factors of malignancy (including US) in nodules with indication for FNA whose cytology result was classified as "nondiagnostic" on 2 occasions. The sample consisted of 158 patients with thyroid nodules >5 mm with indication for FNA whose material obtained by US-guided FNA was classified as nondiagnostic on 2 occasions according to the criteria of the Bethesda classification. Papillary thyroid carcinoma (PTC) was confirmed by histology in 23/158 cases (14.5%). Sex, age, family history of PTC, palpation, number of nodules, serum TSH, or circulating antithyroperoxidase antibodies were not predictors of malignancy. Only US predicted risk of malignancy. US showed a sensitivity of 65.2% and a specificity of 90.4%. When US indicated the nodule to be "suspicious for malignancy", histology confirmed PTC in 15/28 cases (positive predictive value 53.4%). When the nodule showed no suspicious US features, histology detected malignancy in only 8/130 cases (negative predictive value 94%). The diagnostic accuracy of the US was 89.5%. The present results suggest that, in cases of patients with thyroid nodules and repeatedly nondiagnostic cytology, ultrasonographic findings represent an excellent parameter for the selection of those who could be followed up by periodic US and those who should be referred for thyroidectomy because of the risk of malignancy.


Assuntos
Citodiagnóstico/métodos , Nódulo da Glândula Tireoide/diagnóstico por imagem , Nódulo da Glândula Tireoide/patologia , Adolescente , Adulto , Idoso , Biópsia por Agulha Fina , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Ultrassonografia , Adulto Jovem
3.
Endocrine ; 2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-39080211

RESUMO

PURPOSE: This article aims to comprehensively analyze the unique challenges in managing patients with metastatic Differentiated Thyroid Cancer (DTC) that develop radioiodine-refractory disease, especially in developing countries in Latin America. We discuss key contentious aspects of their treatment, such as the optimal timing for initiating systemic therapy, the choice of first-line medications, the appropriate timing for requesting molecular interrogation, and the challenges associated with accessing these drugs and molecular panels. METHODS: To illustrate these challenges and enhance understanding, we present five real clinical cases from the authors' experiences. RESULTS: Patients with Differentiated Thyroid Cancer (DTC) generally have an excellent prognosis, with an overall 10-year survival rate exceeding 97%. However, approximately 5% of DTC patients, especially those with distant metastases, may develop radioiodine-refractory disease, reducing survival rates. Access to medications remains difficult and time-consuming, particularly for patients within the public healthcare system. Urgent discussions on drug pricing involving all stakeholders are imperative. To break free from complacency, stakeholders must prioritize patient well-being by advocating for evidence-based drug pricing, increased participation in clinical trials, and streamlined regulatory processes. CONCLUSION: Beyond the recognized need for prospective randomized clinical trials to determine the optimal first-line drug and the timing of molecular testing, this type of manuscript plays a pivotal role in stimulating discussions and disseminating comprehensive knowledge about the challenges associated with treating and monitoring patients with radioiodine-refractory thyroid carcinoma, especially in developing countries.

4.
Eur Phys J Plus ; 138(3): 216, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36911363

RESUMO

In this paper, we provide evidence that Zn 2 + ions play a role in the SARS-CoV-2 virus strategy to escape the immune response mediated by the BST2-tetherin host protein. This conclusion is based on sequence analysis and molecular dynamics simulations as well as X-ray absorption experiments [1].

5.
Front Mol Biosci ; 9: 878017, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35712353

RESUMO

This work studies the stability of wild-type frataxin and some of its variants found in cancer tissues upon Co2+ binding. Although the physiologically involved metal ion in the frataxin enzymatic activity is Fe2+, as it is customarily done, Co2+ is most often used in experiments because Fe2+ is extremely unstable owing to the fast oxidation reaction Fe2+ → Fe3+. Protein stability is monitored following the conformational changes induced by Co2+ binding as measured by circular dichroism, fluorescence spectroscopy, and melting temperature measurements. The stability ranking among the wild-type frataxin and its variants obtained in this way is confirmed by a detailed comparative analysis of the XAS spectra of the metal-protein complex at the Co K-edge. In particular, a fit to the EXAFS region of the spectrum allows positively identifying the frataxin acidic ridge as the most likely location of the metal-binding sites. Furthermore, we can explain the surprising feature emerging from a detailed analysis of the XANES region of the spectrum, showing that the longer 81-210 frataxin fragment has a smaller propensity for Co2+ binding than the shorter 90-210 one. This fact is explained by the peculiar role of the N-terminal disordered tail in modulating the protein ability to interact with the metal.

6.
Hematol Oncol Stem Cell Ther ; 14(2): 126-133, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32997971

RESUMO

OBJECTIVE/BACKGROUND: Hematopoietic stem cell transplantation (HSCT) is a treatment for benign and malignant hematological diseases. These aggressive treatments cause reduced levels of physical activity, decreased lung function, and worse quality of life. Alterations in pulmonary function tests before HSCT are associated with the risk of respiratory failure and early mortality. The objective of this study was to evaluate functional capacity and lung function before and after HSCT and identify the predictors of mortality after 2 years. METHODS: A prospective cohort study was carried out with individuals with oncohematological diseases. The evaluations were carried out in two moments during hospitalization and at hospital discharge. Follow-up was carried out after 48 months. Assessments were carried out on 34 adults, using spirometry, manovacuometry, 6-Minute Walk Test (6MWT), Handgrip Strength Test, and 30-Second Chair Stand Test (30-s CST). RESULTS: There was a statistically significant reduction for the variables in forced vital capacity, forced expiratory volume predicted in the 1st second, Tiffeneau index, handgrip strength, and distance covered (% predicted) on the 6MWT (p < .05). There was a significant difference in the 30-s CST when individuals were compared according to the type of transplant. We found that a 10% reduction in the values of maximum inspiratory pressure (MIP) can predict an increased risk for mortality. CONCLUSIONS: Individuals undergoing HSCT have reduced functional capacity, lung function, and muscle strength during the hospitalization phase. Reduction in the values of MIP increases the risk of nonrelapse mortality.


Assuntos
Neoplasias Hematológicas/terapia , Transplante de Células-Tronco Hematopoéticas , Pulmão/fisiologia , Força Muscular , Adulto , Humanos , Medidas de Volume Pulmonar , Cuidados Pré-Operatórios , Estudos Prospectivos , Qualidade de Vida , Testes de Função Respiratória , Adulto Jovem
7.
J Exp Med ; 181(2): 817-21, 1995 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-7836934

RESUMO

T cells play a major role in the development of insulin-dependent diabetes mellitus (IDDM) in nonobese diabetic (NOD) mice. Administration of interleukin 12 (IL-12), a key cytokine which guides the development of T helper type 1 (Th1) CD4+ T cells, induces rapid onset of IDDM in NOD, but not in BALB/c mice. Histologically, IL-12 administration induces massive infiltration of lymphoid cells, mostly T cells, in the pancreatic islets of NOD mice. CD4+ pancreas-infiltrating T cells, after activation by insolubilized anti T cell receptor antibody, secrete high levels of interferon gamma and low levels of IL-4. Therefore, IL-12 administration accelerates IDDM development in genetically susceptible NOD mice, and this correlates with increased Th1 cytokine production by islet-infiltrating cells. These results hold implications for the pathogenesis, and possibly for the therapy of IDDM and of other Th1 cell-mediated autoimmune diseases.


Assuntos
Doenças Autoimunes/imunologia , Diabetes Mellitus Tipo 1/imunologia , Interleucina-12/farmacologia , Linfócitos T/imunologia , Animais , Doenças Autoimunes/etiologia , Células CHO , Cricetinae , Diabetes Mellitus Tipo 1/etiologia , Feminino , Interferon gama/biossíntese , Interleucina-12/administração & dosagem , Interleucina-4/biossíntese , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos NOD , Linfócitos T/citologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismo
8.
J Exp Med ; 185(2): 317-28, 1997 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-9016880

RESUMO

The signals controlling the checkpoints of dendritic cells (DC) maturation and the correlation between phenotypical and functional maturational stages were investigated in a defined model system of growth factor-dependent immature mouse DC. Three sequential stages of DC maturation (immature, mature, and apoptotic) were defined and characterized. Immature DC (stage 1) had low expression of costimulatory molecules, highly organized cytoskeleton, focal adhesion plaques, and slow motility; accordingly, they were very efficient in antigen uptake and processing of soluble proteins. Further, at this stage most of major histocompatibility complex class II molecules were within cytoplasmic compartments consistent with a poor allostimulatory capacity. Bacteria or cytokines were very efficient in inducing progression from stage 1 towards stage 2 (mature). Morphological changes were observed by confocal analysis including depolymerization of F-actin and loss of vinculin containing adhesive structures which correlates with acquisition of high motility. Antigen uptake and presentation of native protein antigen was reduced. In contrast, presentation of immunogenic peptides and allostimulatory activity became very efficient and secretion of IL-12 p75 was detectable after antigen presentation. This functional DC maturation ended by apoptotic cell death, and no reversion to the immature phenotype was observed.


Assuntos
Células Dendríticas/citologia , Animais , Linhagem da Célula , Células Cultivadas , Citocinas/farmacologia , Células Dendríticas/imunologia , Endocitose , Feminino , Interleucina-12/biossíntese , Macrófagos/citologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Fenótipo , Baço/citologia
9.
Int J Androl ; 33(3): 475-88, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-19508330

RESUMO

Benign prostatic hyperplasia (BPH) is a common disorder affecting 50-80% of the aged male population. Androgens and age have been traditionally considered the main determinants of prostate enlargement, but in the last years a potentially important role of chronic inflammation in BPH pathogenesis has emerged. Bacterial and non-infectious chronic prostatitis could represent inciting factors leading to tissue hyperproliferation, possibly via the recently demonstrated antigen-presenting capacity of prostatic stromal cells, enabling them to induce and sustain intraglandular immune responses. The prostate growth-promoting chemokine IL-8 could represent a direct link between chronic prostate inflammation and autocrine/paracrine stromal cell proliferation, in agreement with its marked secretion induced in BPH stromal cells by a combination of Th1 and Th17 cell-derived inflammatory cytokines. BPH stromal cells express the vitamin D receptor (VDR), which is up-regulated by exposure to inflammatory stimuli. The non-hypercalcaemic VDR agonist elocalcitol, shown to arrest BPH development by decreasing the intra-prostatic androgen signalling without directly interfering with systemic androgen action, exerts immunoregulatory and anti-inflammatory properties in different prostatic pathology characterized by growth and inflammation. The mechanism of action of VDR agonists supports an important role of chronic inflammation in BPH pathogenesis and strengthens the concept of these agents as a therapeutic option for pharmacological treatment of BPH.


Assuntos
Inflamação/imunologia , Hiperplasia Prostática , Androgênios/fisiologia , Androgênios/uso terapêutico , Anti-Inflamatórios/uso terapêutico , Calcitriol/análogos & derivados , Quimiocinas/uso terapêutico , Doença Crônica , Citocinas/imunologia , Citocinas/uso terapêutico , Humanos , Inflamação/tratamento farmacológico , Interleucina-8/uso terapêutico , Masculino , Próstata/metabolismo , Próstata/patologia , Hiperplasia Prostática/tratamento farmacológico , Hiperplasia Prostática/etiologia , Hiperplasia Prostática/patologia , Prostatite/complicações , Prostatite/tratamento farmacológico , Prostatite/patologia , Receptores de Calcitriol/agonistas , Receptores de Calcitriol/metabolismo , Transdução de Sinais , Células Estromais/metabolismo , Células Estromais/patologia
10.
J Endocrinol Invest ; 33(10): 730-8, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20386089

RESUMO

BACKGROUND: Chronic inflammation is now considered a determinant of benign prostatic hyperplasia (BPH), promoting, together with the hormonal milieu, prostate overgrowth and lower urinary tract symptoms (LUTS). Prostatic urethra actively participates in determining progression of LUTS associated with BPH. AIM: To investigate the expression of the vitamin D receptor (VDR) and the ability of the VDR agonist elocalcitol to reduce inflammatory responses in human prostatic urethra (hPU) cells. MATERIALS AND METHODS: Human prostatic urethra, prostate and bladder neck were obtained from patients affected by BPH. Immunohistochemical studies for VDR expression were performed in tissue samples, from which primary cell cultures were also derived. In hPU cells, proliferation and chemiotaxis were studied, along with Rho kinase (ROCK) activity (MYPT-1 phosphorylation) by western blot. Quantitative RT-PCR was performed for VDR, cyclooxygenase (COX-2), and interleukin (IL)-8 expression. RESULTS: Urethra displays higher VDR expression compared to prostate and bladder neck tissues. The VDR agonist elocalcitol partially reverts COX-2 and IL-8 mRNA upregulation induced by a pro-inflammatory cytokine mixture (IL-17, interferon-γ, tumor necrosis factor-α) and inhibits cell migration in urethral cells. Elocalcitol prevents activation of ROCK, as previously demonstrated in bladder and prostate cell cultures. CONCLUSIONS: Our results suggest that prostatic urethra is, within the lower urinary tract, a novel target for VDR agonists, as shown by the capacity of elocalcitol to inhibit ROCK activity and to limit inflammatory responses in human primary urethra cells.


Assuntos
Calcitriol/análogos & derivados , Próstata/metabolismo , Receptores de Calcitriol/agonistas , Receptores de Calcitriol/genética , Uretra/metabolismo , Idoso , Calcitriol/farmacologia , Técnicas de Cultura de Células , Células Cultivadas , Citocinas/genética , Citocinas/metabolismo , Avaliação Pré-Clínica de Medicamentos , Expressão Gênica , Humanos , Ligantes , Masculino , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Próstata/efeitos dos fármacos , Próstata/patologia , Hiperplasia Prostática/genética , Hiperplasia Prostática/metabolismo , Hiperplasia Prostática/patologia , Hiperplasia Prostática/cirurgia , Receptores de Calcitriol/metabolismo , Uretra/efeitos dos fármacos , Uretra/patologia , Bexiga Urinária/metabolismo , Bexiga Urinária/patologia
11.
Int J Popul Data Sci ; 4(2): 1140, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-34095542

RESUMO

The Centre for Data and Knowledge Integration for Health (CIDACS) was created in 2016 in Salvador, Bahia-Brazil with the objective of integrating data and knowledge aiming to answer scientific questions related to the health of the Brazilian population. This article details our experiences in the establishment and operations of CIDACS, as well as efforts made to obtain high-quality linked data while adhering to security, ethical use and privacy issues. Every effort has been made to conduct operations while implementing appropriate structures, procedures, processes and controls over the original and integrated databases in order to provide adequate datasets to answer relevant research questions. Looking forward, CIDACS is expected to be an important resource for researchers and policymakers interested in enhancing the evidence base pertaining to different aspects of health, in particular when investigating, from a nation-wide perspective, the role of social determinants of health and the effects of social and environmental policies on different health outcomes.

12.
Curr Opin Immunol ; 12(1): 114-21, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10679408

RESUMO

Dendritic cells are known as the most efficient antigen-presenting cell type to activate naïve T cells; however, they are able to do more than just efficiently present antigen to T cells. They are key modulators of the immune response that can influence Th cell differentiation by preferentially inducing Th type 1 or 2 cell responses, and the differential polarisation of CD4(+) T cells appears to be mediated by discrete dendritic cell subsets.


Assuntos
Apresentação de Antígeno , Células Dendríticas/classificação , Linfócitos T/imunologia , Animais , Antígenos de Diferenciação de Linfócitos T , Citocinas/metabolismo , Humanos , Camundongos
13.
Benef Microbes ; 8(4): 597-604, 2017 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-28555501

RESUMO

In this study, we aimed to investigate some functional characteristics and the immunomodulatory properties of three strains of Lactobacillus plantarum of dairy origin which, in a previous screening, showed to be candidate probiotics. Genome sequencing and comparative genomics, which confirmed the presence of genes involved in folate and riboflavin production and in the immune response of dendritic cells (DCs), prompted us to investigate the ability of the three strains to accumulate the two vitamins and their immunomodulation properties. The ability of the three strains to release antioxidant components in milk was also investigated. Small amounts of folate and riboflavin were produced by the three strains, while they showed a good antioxidant capacity in milk with FRAP method. The immune response experiments well correlated with the presence of candidate genes influencing in DCs cytokine response to L. plantarum. Specifically, the amounts of secreted cytokins by DCs after stimulation with cells of Lp790, Lp813 and Lp998 resulted pro-inflammatory whereas stimulation with culture supernatants (postbiotics) inhibited the release of interleukin (IL)-12p70 and increased the release of the anti-inflammatory IL-10 cytokine. This study adds further evidence on the importance of L. plantarum in human health. Understanding how probiotics (or postbiotics) work in preclinical models can allow a rational choice of the different strains for clinical and/or commercial use.


Assuntos
Células Dendríticas/efeitos dos fármacos , Fatores Imunológicos/administração & dosagem , Lactobacillus plantarum/genética , Leite/microbiologia , Probióticos/administração & dosagem , Animais , Bovinos , Células Cultivadas , Células Dendríticas/imunologia , Genoma Bacteriano , Genômica , Humanos , Interleucina-10/genética , Interleucina-10/imunologia , Interleucina-12/genética , Interleucina-12/imunologia , Lactobacillus plantarum/classificação , Lactobacillus plantarum/imunologia , Lactobacillus plantarum/isolamento & purificação , Filogenia
14.
Int J Tuberc Lung Dis ; 21(7): 790-796, 2017 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-28633704

RESUMO

OBJECTIVE: To evaluate the impact of the Brazilian cash transfer programme (Bolsa Família Programme, BFP) on tuberculosis (TB) incidence in Brazil from 2004 to 2012. DESIGN: We studied tuberculosis surveillance data using a combination of an ecological multiple-group and time-trend design covering 2458 Brazilian municipalities. The main independent variable was BFP coverage and the outcome was the TB incidence rate. All study variables were obtained from national databases. We used fixed-effects negative binomial models for panel data adjusted for selected covariates and a variable representing time. RESULTS: After controlling for covariates, TB incidence rates were significantly reduced in municipalities with high BFP coverage compared with those with low and intermediate coverage (in a model with a time variable incidence rate ratio = 0.96, 95%CI 0.93-0.99). CONCLUSION: This was the first evidence of a statistically significant association between the increase in cash transfer programme coverage and a reduction in TB incidence rate. Our findings provide support for social protection interventions for tackling TB worldwide.


Assuntos
Modelos Estatísticos , Assistência Pública , Tuberculose/epidemiologia , Brasil/epidemiologia , Cidades , Humanos , Incidência , Vigilância da População , Pobreza , Fatores de Tempo , Tuberculose/prevenção & controle
15.
Microbes Infect ; 7(7-8): 1033-9, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15919222

RESUMO

Dendritic cells (DCs) induce and regulate T-cell responses, and tolerogenic DCs can promote the development of regulatory T cells with suppressive activity. The possibility of manipulating DCs using different pharmacological or biological agents, enabling them to exert tolerogenic activities, could be exploited to better control a variety of chronic inflammatory conditions, from autoimmune diseases to allograft rejection.


Assuntos
Células Dendríticas/fisiologia , Linfócitos T/fisiologia , Animais , Doenças Autoimunes/imunologia , Células Dendríticas/efeitos dos fármacos , Rejeição de Enxerto/imunologia , Humanos , Imunossupressores/farmacologia , Ativação Linfocitária , Receptores de Calcitriol/agonistas , Receptores de Superfície Celular/metabolismo
16.
Hum Gene Ther ; 12(8): 905-20, 2001 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-11387056

RESUMO

Systemic administration of antiinflammatory molecules to patients affected by immune-mediated inflammatory demyelinating diseases of the central nervous system (CNS) has limited therapeutic efficacy due to the presence of the blood-brain barrier (BBB). We found that three of five rhesus monkeys injected intrathecally with a replication-defective herpes simplex virus (HSV) type 1-derived vector engineered with the human interleukin 4 (IL-4) gene were protected from an hyperacute and lethal form of experimental autoimmune encephalomyelitis induced by whole myelin. The intrathecally injected vector consistently diffused within the CNS via the cerebrospinal fluid and infected ependymal cells, which in turn sustained in situ production of IL-4 without overt immunological or toxic side effects. In EAE-protected monkeys, IL-4-gene therapy significantly decreased the number of brain as well as spinal cord inflammatory perivenular infiltrates and the extent of demyelination, necrosis, and axonal loss. The protective effect was associated with in situ downregulation of inflammatory mediators such as tumor necrosis factor alpha (TNF-alpha) and monocyte chemoattractant protein 1 (MCP-1), upregulation of transforming growth factor beta (TGF-beta), and preservation of BBB integrity. Our results indicate that intrathecal delivery of HSV-1-derived vectors containing antiinflammatory cytokine genes may play a major role in the future therapeutic armamentarium of inflammatory CNS-confined demyelinating diseases and, in particular, in the most fulminant forms where conventional therapeutic approaches have, so far, failed to achieve a satisfactory control of the disease evolution.


Assuntos
Doenças Autoimunes/genética , Sistema Nervoso Central/metabolismo , Encefalomielite/genética , Terapia Genética/métodos , Vetores Genéticos , Herpesvirus Humano 1/genética , Interleucina-4/genética , Animais , Doenças Autoimunes/prevenção & controle , Barreira Hematoencefálica , Encéfalo/patologia , Divisão Celular , Quimiocina CCL2/biossíntese , Citocinas/biossíntese , Regulação para Baixo , Encefalomielite/prevenção & controle , Ensaio de Imunoadsorção Enzimática , Humanos , Interleucina-4/biossíntese , Macaca mulatta , Imageamento por Ressonância Magnética , Masculino , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Medula Espinal/imunologia , Linfócitos T/citologia , Fatores de Tempo , Fator de Crescimento Transformador beta/biossíntese , Fator de Necrose Tumoral alfa/biossíntese , Regulação para Cima
17.
Biopolymers ; 50(6): 613-29, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10508964

RESUMO

The local dynamics of a double-stranded DNA d(TpCpGpCpG)(2) is obtained to second order in the mode-coupling expansion of the Smoluchowski diffusion theory. The time correlation functions of bond variables are derived and the (13)C-nmr spin-lattice relaxation times T(1) of different (13)C along the chains are calculated and compared to experimental data from the literature at three frequencies. The DNA is considered as a fluctuating three-dimensional structure undergoing rotational diffusion. The fluctuations are evaluated using molecular dynamics simulations, with the ensemble averages approximated by time averages along a trajectory of length 1 ns. Any technique for sampling the configurational space can be used as an alternative. For a fluctuating three-dimensional (3D) structure using the three first-order vector modes of lower rates, higher order basis sets of second-rank tensor are built to give the required mode coupling dynamics. Second- and even first-order theories are found to be in close agreement with the experimental results, especially at high frequency, where the differences in T(1) for (13)C in the base pairs, sugar, and backbone are well described. These atomistic calculations are of general application for studying, on a molecular basis, the local dynamics of fluctuating 3D structures such as double-helix DNA fragments, proteins, and protein-DNA complexes. Copyright 1999 John Wiley & Sons, Inc.

18.
J Biomol Struct Dyn ; 17(4): 673-85, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10698105

RESUMO

The local dynamics of a double stranded DNA fragment [d(CpGpCpApApApTpTpTpGpCpG)]2 of twelve base pairs is obtained to second order in the mode-coupling expansion of the Smoluchowski diffusion theory. The DNA is considered a fluctuating three-dimensional (3D) structure undergoing rotational diffusion. The starting structure for the calculations is the B canonical structure of the fragment, while the fluctuations are evaluated using molecular dynamics simulations, with the ensemble averages approximated by time averages along a trajectory of length 1.5 ns. The rotational dynamics of the bonds along the double strands are calculated and compared to experimental NMR relaxation rates of different 13C along the sequence: R(Cz), R(Cxy) and R(Hz-->Cz). For a fluctuating 3D structure the mode-coupling diffusion theory is found to be in good agreement with several relative characteristics of the experimental relaxation parameters, while motivations are given for the few differences which are due mainly to poor statistics or to inaccuracies in the diffusion model. With a view to application to larger DNA fragments, discussion is dedicated to the validity of reducing the number of degrees of freedom in the double helix statistics by grouping the atoms in rigid fragments (e.g. the backbone atoms, the sugar atoms and the base atoms of each nucleotide). Consideration is given to the effect on local dynamics properties of reduced descriptions that include only three or four rigid bodies per nucleotide as well as five rigid bodies per base pair. It is found that in general these approximations almost uniformly produce slight increase in the correlation time pattern, which grows as the rigidity in the model increases. The relative effects on the dynamic pattern for the most accurate rigid body models are modest. The errors in C1' and C5' mobilities are more significant if C5' is included in the backbone rigid body. These results offer new tools to analyse NMR relaxation behaviour and new perspectives in studying the role of dynamics in biological macromolecules.


Assuntos
DNA/química , Oligonucleotídeos/química , Algoritmos , Simulação por Computador , Espectroscopia de Ressonância Magnética , Modelos Estatísticos , Conformação de Ácido Nucleico
19.
Braz J Med Biol Res ; 34(2): 195-202, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11175494

RESUMO

Until recently, dietary sources of nucleotides were thought not to be essential for good nutrition. Certain states with higher metabolic demands may require larger amounts that cannot be provided by endogenous production. The objective of the present study was to determine the action of nucleotides on the recovery from lactose-induced diarrhea in weaned rats. Thirty-six weanling Fisher rats were divided into two groups. Group 1 received a standard diet and group 2 received a diet containing lactose in place of starch. On the 10th day, six animals per group were sacrificed for histopathological evaluation. The remaining animals were divided into two other subgroups, each with 6 animals, receiving a control diet, a control diet with nucleotides (0.05% adenosine monophosphate, 0.05% guanosine monophosphate, 0.05% cytidine monophosphate, 0.05% uridine monophosphate and 0.05% inosine monophosphate), a diet with lactose, and a diet with lactose and nucleotides. On the 32nd day of the experiment all animals were sacrificed. Animals with diarrhea weighed less than animals without diarrhea. The introduction of nucleotides did not lead to weight gain. Mean diet consumption was lower in the group that continued to ingest lactose, with the group receiving lactose plus nucleotides showing a lower mean consumption. Animals receiving lactose had inflammatory reaction and deposits of periodic acid-Schiff-positive material in intestinal, hepatic and splenic tissues. The introduction of nucleotides led to an improvement of the intestinal inflammatory reaction. In lactose-induced diarrhea, when the stimulus is maintained--lactose overload--the nucleotides have a limited action on the weight gain and on recovery of intestinal morphology, although they have a protective effect on hepatic injury and improve the inflammatory response.


Assuntos
Diarreia/tratamento farmacológico , Intestinos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Nucleosídeos/uso terapêutico , Baço/efeitos dos fármacos , Análise de Variância , Animais , Peso Corporal , Estudos de Casos e Controles , Diarreia/etiologia , Diarreia/patologia , Intestinos/patologia , Lactose , Fígado/patologia , Ratos , Ratos Endogâmicos F344 , Baço/patologia , Desmame
20.
Rev Soc Bras Med Trop ; 33(5): 451-64, 2000.
Artigo em Português | MEDLINE | ID: mdl-11064582

RESUMO

Gonorrhea is a common bacterial infection caused by Neisseria gonorrhoeae, a Gram-negative diplococcus that is transmitted almost exclusively by sexual contact or perinatally. It primarily affects the mucous membranes of the lower genital tract and less frequently those of the rectum, oropharynx, and conjunctivae. Ascending genital infection in women leads to the predominant complication, acute salpingitis, one of the most common causes of female infertility in the world. Since the 1990s, a remarkable surge of information ensued regarding the pathogenesis of gonorrhea and its agent. Gonorrhea has proven difficult to control in most populations and remains a prime example of the influence that social, behavioral, and demographic factors can have on the epidemiology of an infectious disease. The management of gonorrhea and other sexually transmitted infections requires both treatment of the patient as an individual and of his or her sexual partner(s) as a public health measure to interrupt the onward spread of infection and prevent long-term complications.


Assuntos
Gonorreia , Feminino , Gonorreia/diagnóstico , Gonorreia/tratamento farmacológico , Gonorreia/epidemiologia , Gonorreia/etiologia , Humanos , Masculino , Saúde Pública
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