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1.
J Eur Acad Dermatol Venereol ; 34(8): 1842-1850, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31919901

RESUMO

BACKGROUND: Several studies have achieved high-level performance of melanoma detection using convolutional neural networks (CNNs). However, few have described the extent to which the implementation of CNNs improves the diagnostic performance of the physicians. OBJECTIVE: This study is aimed at developing a CNN for detecting acral lentiginous melanoma (ALM) and investigating whether its implementation can improve the initial decision for ALM detection made by the physicians. METHODS: A CNN was trained using 1072 dermoscopic images of acral benign nevi, ALM and intermediate tumours. To investigate whether the implementation of CNN can improve the initial decision for ALM detection, 60 physicians completed a three-stage survey. In Stage I, they were asked for their decisions solely on the basis of dermoscopic images provided to them. In Stage II, they were also provided with clinical information. In Stage III, they were provided with the additional diagnosis and probability predicted by the CNN. RESULTS: The accuracy of ALM detection in the participants was 74.7% (95% confidence interval [CI], 72.6-76.8%) in Stage I and 79.0% (95% CI, 76.7-81.2%) in Stage II. In Stage III, it was 86.9% (95% CI, 85.3-88.4%), which exceeds the accuracy delivered in Stage I by 12.2%p (95% CI, 10.1-14.3%p) and Stage II by 7.9%p (95% CI, 6.0-9.9%p). Moreover, the concordance between the participants considerably increased (Fleiss-κ of 0.436 [95% CI, 0.437-0.573] in Stage I, 0.506 [95% CI, 0.621-0.749] in Stage II and 0.684 [95% CI, 0.621-0.749] in Stage III). CONCLUSIONS: Augmented decision-making improved the performance of and concordance between the clinical decisions of a diverse group of experts. This study demonstrates the potential use of CNNs as an adjoining, decision-supporting system for physicians' decisions.


Assuntos
Melanoma , Neoplasias Cutâneas , Dermoscopia , Humanos , Melanoma/diagnóstico por imagem , Redes Neurais de Computação , Neoplasias Cutâneas/diagnóstico por imagem
2.
Int J Cosmet Sci ; 42(5): 482-493, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32692411

RESUMO

OBJECTIVE: It is conventionally understood that occlusive effects are the retention of excessive water in the stratum corneum (SC), the increase of SC thickness (swelling) and a decrease of the transepidermal water loss. However, the influence of occlusion on water binding properties in the SC is unknown. METHODS: The action of plant-derived jojoba and almond oils, as well as mineral-derived paraffin oil and petrolatum topically applied on human skin, is investigated in vivo using confocal Raman microspectroscopy. To understand the oils' influence on the SC on the molecular level, the depth-dependent hydrogen bonding states of water in the SC and their relationship to the conformation of keratin, concentration of natural moisturizing factor (NMF) molecules and lipid organization were investigated. RESULTS: A significant SC swelling was observed only in petrolatum-treated skin. The water concentration was increased in oil-treated skin in the intermediate SC region (40-70% SC depth). Meanwhile, the amount of free, weakly and tightly bound water increased, and strongly bound water decreased in the uppermost SC region (0-30% SC depth). The NMF concentration of oil-treated skin was significantly lower at 50-70% SC depth. The lateral organization of lipids in oil-treated skin was lower at 0-30% SC depth. The secondary structure of keratin was changed towards an increase of ß-sheet content in mineral-derived oil-treated skin and changed towards an increase of α-helix content in plant-derived oil-treated skin. CONCLUSION: The occlusive properties can be summarized as the increase of free water and the transformation of water from a more strongly to a more weakly hydrogen bonding state in the uppermost SC, although some oils cause insignificant changes of the SC thickness. The accompanied changes in the keratin conformation at the intermediate swelling region of the SC also emphasize the role of keratin in the SC's water-transporting system, that is the water in the SC transports intercellularly and intracellularly in the intermediate swelling region and only intercellularly in the uppermost non-swelling region. Bearing this in mind, almond, jojoba and paraffin oils, which are not occlusive from the conventional viewpoint, have an occlusion effect similar to petrolatum on the SC.


OBJECTIF: Il est généralement entendu que les effets occlusifs consistent en la rétention d'un excès d'eau dans la couche cornée (stratum corneum, SC), l'augmentation d'épaisseur de la SC (gonflement) et une diminution de la perte d'eau trans-épidermique. Cependant, l'influence de l'occlusion sur les propriétés de fixation de l'eau dans le SC est inconnue. MÉTHODES: L'action des huiles de jojoba et d'amande d'origine végétale, ainsi que des huiles de paraffine et de pétrolatum d'origine minérale appliquées topiquement sur la peau humaine est étudiée in vivo à l'aide de la microspectroscopie Raman confocale. Pour comprendre l'influence des huiles sur le SC au niveau moléculaire, on a étudié les états de liaison hydrogène de l'eau dans le SC en fonction de la profondeur et leur relation avec la conformation de la kératine, la concentration des molécules du facteur naturel d'hydratation (NMF) et l'organisation des lipides. RÉSULTATS: Un gonflement significatif de le SC n'a été observé que dans la peau traitée au pétrolatum. La concentration en eau a été augmentée dans la peau traitée au pétrolatum dans la région SC intermédiaire (40-70% de profondeur du SC). En meme temps, la quantité d'eau libre, faiblement et fortement liée augmentait, tandis que l'eau fortement liée diminuait dans la région SC supérieure (0-30% de profondeur du SC). La concentration en NMF de la peau traitée à l'huile était plus basse d´une manière significative à 50-70% de profondeur du SC. L'organisation latérale des lipides dans la peau huilée était plus basse à une profondeur du SC de 0 à 30 %. La structure secondaire de la kératine a été modifiée pour augmenter la teneur en feuillet-ß dans les peaux huilées d'origine minérale et pour augmenter la teneur en hélice α dans les peaux huilées d'origine végétale. CONCLUSION: Les propriétés occlusives peuvent être résumées comme l'augmentation de l'eau libre et la transformation de l'eau d'un état de liaison hydrogène plus fort à un état de liaison hydrogène plus faible dans le SC supérieure, bien que certaines huiles provoquent des changements insignifiants de l'épaisseur de la SC. Les modifications de la conformation de la kératine dans la zone de gonflement intermédiaire du SC soulignent également le rôle de la kératine dans le système de transport de l'eau du SC, c'est-à-dire que l'eau est transportée du SC de manière intercellulaire et intracellulaire dans la zone de gonflement intermédiaire et seulement de manière intercellulaire dans la zone non gonflée la plus élevée. En considérant cela, les huiles d'amande, de jojoba et de paraffine, qui ne sont pas occlusives du point de vue conventionnel, ont un effet d'occlusion similaire à celui du pétrolatum sur le SC.


Assuntos
Epiderme/química , Análise Espectral Raman/métodos , Água/química , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
3.
Hum Reprod ; 33(6): 1071-1078, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29659826

RESUMO

STUDY QUESTION: Are the concentrations of five criteria air pollutants associated with probabilities of biochemical pregnancy loss and intrauterine pregnancy in women? SUMMARY ANSWER: Increased concentrations of ambient particulate matter (PM10), nitrogen dioxide (NO2), carbon monoxide (CO) during controlled ovarian stimulation (COS) and after embryo transfer were associated with a decreased probability of intrauterine pregnancy. WHAT IS KNOWN ALREADY: Exposure to high ambient air pollution was suggested to be associated with low fertility and high early pregnancy loss in women. STUDY DESIGN, SIZE, DURATION: Using a retrospective cohort study design, we analysed 6621 cycles of 4581 patients who underwent one or more fresh IVF cycles at a fertility centre from January 2006 to December 2014, and lived in Seoul at the time of IVF treatment. PARTICIPANTS/MATERIALS, SETTING, METHODS: To estimate patients' individual exposure to air pollution, we computed averages of hourly concentrations of five air pollutants including PM10, NO2, CO, sulphur dioxide (SO2) and ozone (O3) measured at 40 regulatory monitoring sites in Seoul for each of the four exposure periods: period 1 (start of COS to oocyte retrieval), period 2 (oocyte retrieval to embryo transfer), period 3 (embryo transfer to hCG test), and period 4 (start of COS to hCG test). Hazard ratios (HRs) from the time-varying Cox-proportional hazards model were used to estimate probabilities of biochemical pregnancy loss and intrauterine pregnancy for an interquartile range (IQR) increase in each air pollutant concentration during each period, after adjusting for individual characteristics. We tested the robustness of the result using generalised linear mixed model, accounting for within-woman correlation. MAIN RESULTS AND THE ROLE OF CHANCE: Mean age of the women was 35 years. Average BMI was 20.9 kg/m2 and the study population underwent 1.4 IVF cycles on average. Cumulative pregnancy rate in multiple IVF cycles was 51.3% per person. Survival analysis showed that air pollution during periods 1 and 3 was generally associated with IVF outcomes. Increased NO2 (adjusted HR = 0.93, 95% CI: 0.87, 0.99) and CO (0.94, 95% CI: 0.89, 1.00) during period 1 were associated with decreased probability of intrauterine pregnancy. PM10 (0.92, 95% CI: 0.85, 0.99), NO2 (0.93, 95% CI = 0.86, 1.00) and CO (0.93, 95% CI: 0.87, 1.00) levels during period 3 were also inversely associated with intrauterine pregnancy. Both PM10 (1.17, 95% CI: 1.04 1.33) and NO2 (1.18, 95% CI: 1.03, 1.34) during period 3 showed positive associations with biochemical pregnancy loss. LIMITATIONS, REASONS FOR CAUTION: The district-specific ambient air pollution treated as an individual exposure may not represent the actual level of each woman's exposure to air pollution. Smoking, working status, parity or gravidity of women, and semen analysis data were not included in the analysis. WIDER IMPLICATIONS OF THE FINDINGS: This study provided evidence of an association between increased ambient concentrations of PM10, NO2 and CO and reduced probabilities for achieving intrauterine pregnancy using multiple IVF cycle data. Specifically, our results indicated that lower intrauterine pregnancy rates in IVF cycles may be linked to ambient air pollution during COS and the post-transfer period. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013 R1A6A3A04059017, 2016 R1D1A1B03933410 and 2018 R1A2B6004608) and the National Cancer Center of Korea (NCC-1810220-01). The authors report no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.


Assuntos
Poluentes Atmosféricos/toxicidade , Poluição do Ar/efeitos adversos , Fertilização in vitro/estatística & dados numéricos , Taxa de Gravidez , Adulto , Poluição do Ar/estatística & dados numéricos , Monóxido de Carbono/toxicidade , Feminino , Fertilização in vitro/métodos , Humanos , Modelos Lineares , Dióxido de Nitrogênio/toxicidade , Material Particulado/toxicidade , Gravidez , Modelos de Riscos Proporcionais , República da Coreia , Estudos Retrospectivos
4.
Eur Cell Mater ; 35: 209-224, 2018 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-29652075

RESUMO

The success of cell-based approaches for the treatment of cartilage defects requires an optimal autologous cell source with chondrogenic differentiation ability that maintains its differentiated properties and stability following implantation. The objective of this study was to compare the chondrogenic capacity of mesenchymal stem cells (MSCs) isolated from lipoaspirates (ASCs) and the infrapatellar fat pad (IFPSCs) of osteoarthritic patients and treated with transforming growth factor (TGF)-ß family-related growth factors. Cells were cultured for 6 weeks in a 3D pellet culture system with the chimeric activin A/bone morphogenic protein (BMP)-2 ligand (AB235), the chimeric nodal/BMP-2 ligand (NB260) or BMP-2. To investigate the stability of the new cartilage, ASCs-treated pellets were transplanted subcutaneously into severe combined immunodeficiency (SCID) mice. Histological and immunohistochemical assessment confirmed that the growth factors induced cartilage differentiation in both isolated cell types. However, reverse transcription-quantitative PCR results showed that ASCs presented a higher chondrogenic potential than IFPSCs. In vivo results revealed that AB235-treated ASCs pellets were larger in size and could form stable cartilage-like tissue as compared to NB260-treated pellets, while BMP-2-treated pellets underwent calcification. The chondrogenic induction of ASCs by AB235 treatment was mediated by SMAD2/3 activation, as proved by immunofluorescence analysis. The results of this study indicated that the combination of ASCs and AB235 might lead to a cell-based cartilage regeneration treatment.


Assuntos
Tecido Adiposo/patologia , Diferenciação Celular/efeitos dos fármacos , Separação Celular , Condrogênese/efeitos dos fármacos , Lipectomia , Osteoartrite/patologia , Células-Tronco/patologia , Fator de Crescimento Transformador beta/farmacologia , Idoso , Animais , Feminino , Humanos , Masculino , Camundongos SCID , Pessoa de Meia-Idade , Fenótipo , Proteínas Smad/metabolismo , Transplante de Células-Tronco
5.
Asian-Australas J Anim Sci ; 29(11): 1664-1674, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27488844

RESUMO

This research analyzed the effect of ß-glucan that is expected to alleviate the production of the inflammatory mediator in macrophagocytes, which are processed by the lipopolysaccharide (LPS) of Escherichia. The incubated layer was used for a nitric oxide (NO) analysis. The DNA-binding activation of the small unit of nuclear factor-κB was measured using the enzyme-linked immunosorbent assay-based kit. In the RAW264.7 cells that were vitalized by Escherichia coli (E. coli) LPS, the ß-glucan inhibited both the combatant and rendering phases of the inducible NO synthase (iNOS)-derived NO. ß-Glucan increased the expression of the heme oxygenase-1 (HO-1) in the cells that were stimulated by E. coli LPS, and the HO-1 activation was inhibited by the tin protoporphyrin IX (SnPP). This shows that the NO production induced by LPS is related to the inhibition effect of ß-glucan. The phosphorylation of c-Jun N-terminal kinases (JNK) and the p38 induced by the LPS were not influenced by the ß-glucan, and the inhibitory κB-α (IκB-α) decomposition was not influenced either. Instead, ß-glucan remarkably inhibited the phosphorylation of the signal transducer and activator of transcription-1 (STAT1) that was induced by the E. coli LPS. Overall, the ß-glucan inhibited the production of NO in macrophagocytes that was vitalized by the E .coli LPS through the HO-1 induction and the STAT1 pathways inhibition in this research. As the host immune response control by ß-glucan weakens the progress of the inflammatory disease, ß-glucan can be used as an effective immunomodulator.

7.
J Periodontal Res ; 50(6): 737-47, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25601508

RESUMO

BACKGROUND AND OBJECTIVE: Caffeic acid phenethyl ester (CAPE) has numerous potentially beneficial properties, including antioxidant, immunomodulatory and anti-inflammatory activities. However, the effect of CAPE on periodontal disease has not been studied before. This study was designed to investigate the efficacy of CAPE in ameliorating the production of proinflammatory mediators in macrophages activated by lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen implicated in periodontal disease. MATERIAL AND METHODS: LPS from P. intermedia ATCC 25611 was isolated by using the standard hot phenol-water method. Culture supernatants were assayed for nitric oxide (NO), interleukin (IL)-1ß and IL-6. We used real-time polymerase chain reaction to quantify inducible NO synthase, IL-1ß, IL-6, heme oxygenase (HO)-1 and suppressors of cytokine signaling (SOCS) 1 mRNA expression. HO-1 protein expression and levels of signaling proteins were assessed by immunoblot analysis. DNA-binding activities of NF-κB subunits were analyzed by using the enzyme-linked immunosorbent assay-based kits. RESULTS: CAPE exerted significant inhibitory effects on P. intermedia LPS-induced production of NO, IL-1ß and IL-6 as well as their mRNA expression in RAW264.7 cells. CAPE-induced HO-1 expression in cells activated with P. intermedia LPS, and selective inhibition of HO-1 activity by tin protoporphyrin IX attenuated the inhibitory effect of CAPE on LPS-induced NO production. CAPE did not interfere with IκB-α degradation induced by P. intermedia LPS. Instead, CAPE decreased nuclear translocation of NF-κB p65 and p50 subunits induced with LPS, and lessened LPS-induced p50 binding activity. Further, CAPE showed strong inhibitory effects on LPS-induced signal transducer and activator of transcription 1 and 3 phosphorylation. Besides, CAPE significantly elevated SOCS1 mRNA expression in P. intermedia LPS-stimulated cells. CONCLUSION: Modulation of host response by CAPE may represent an attractive strategy towards the treatment of periodontal disease. In vivo studies are required to appraise the potential of CAPE further as an immunomodulator in the treatment of periodontal disease.


Assuntos
Ácidos Cafeicos/metabolismo , Citocinas/metabolismo , Fatores Imunológicos/metabolismo , Lipopolissacarídeos/metabolismo , Macrófagos/efeitos dos fármacos , Óxido Nítrico/metabolismo , Álcool Feniletílico/análogos & derivados , Animais , Perfilação da Expressão Gênica , Lipopolissacarídeos/isolamento & purificação , Camundongos , NF-kappa B/metabolismo , Álcool Feniletílico/metabolismo , Prevotella intermedia/química , Reação em Cadeia da Polimerase em Tempo Real
8.
Phys Chem Chem Phys ; 17(28): 18449-55, 2015 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-26107530

RESUMO

The gel-liquid crystal phase transition has been studied by the temperature and frequency dependent dielectric relaxation behavior of liposomes in an aqueous solution (40 g L(-1) DPPC-water mixture). Four relaxation processes were observed in the frequency range from 40 Hz to 30 GHz which were ascribed to different molecular mechanisms, related to the structural units of the system. The gel-liquid crystal phase transition was also described very accurately from the temperature-dependent dielectric relaxation strength, relaxation time and symmetric shape parameter of the relaxation functions obtained from the fitting procedure. Relaxation process 3, obtained from the dielectric fitting procedure, was confirmed by dielectric modulus analysis. A comparison of the lipid membrane with non-biological systems like liquid crystals was performed. It was determined that the lipid membrane has a ferroelectric liquid crystal like behavior. Process 3 is comparable to the soft mode relaxation process observed in ferroelectric liquid crystals which was detected close to the smectic-C*-smectic-A phase transition. Differential scanning calorimetry was also used to confirm the gel-liquid crystal phase transition of this mixture.


Assuntos
Lipossomos/química , 1,2-Dipalmitoilfosfatidilcolina/química , Varredura Diferencial de Calorimetria , Géis/química , Cristais Líquidos/química , Simulação de Dinâmica Molecular , Temperatura , Água/química
10.
J Nanosci Nanotechnol ; 11(7): 6122-5, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22121670

RESUMO

Understanding the interaction between the magnetic domain wall and the various artificial defects in ferromagnetic nanowires has been of utmost importance for the future realization of the spintronic devices based on the magnetic domain wall motion in nanowires. In this work, the chirality filter effect of the magnetic domain wall in T-shaped ferromagnetic nanowires with a stray field filter was investigated via micromagnetic simulation. A tapered wire was attached to the flat nanowires to form a potential barrier or well for the domain wall propagating along them. For the domain wall passing through the potential barrier or the potential well, the spin structure of the domain wall and the interaction between the domain wall and the potential barrier/well were investigated in detail. The chirality-dependent translational positioning of the domain wall was intensively examined for the potential barrier and potential well cases. The domain wall chirality transmission on relatively long length scales using a series of potential wells was explored.

11.
J Exp Med ; 185(4): 621-8, 1997 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-9034141

RESUMO

Recent studies have identified several coreceptors that are required for fusion and entry of Human Immunodeficiency Virus type 1 (HIV-1) into CD4+ cells. One of these receptors, CCR5, serves as a coreceptor for nonsyncytium inducing (NSI), macrophage-tropic strains of HIV-1, while another, fusin or CXCR-4, functions as a coreceptor for T cell line-adapted, syncytium-inducing (SI) strains. Using sequential primary isolates of HIV-1, we examined whether viruses using these coreceptors emerge in vivo and whether changes in coreceptor use are associated with disease progression. We found that isolates of HIV-1 from early in the course of infection predominantly used CCR5 for infection. However, in patients with disease progression, the virus expanded its coreceptor use to include CCR5, CCR3, CCR2b, and CXCR-4. Use of CXCR-4 as a coreceptor was only seen with primary viruses having an SI phenotype and was restricted by the env gene of the virus. The emergence of variants using this coreceptor was associated with a switch from NSI to SI phenotype, loss of sensitivity to chemokines, and decreasing CD4+ T cell counts. These results suggest that HIV-1 evolves during the course of infection to use an expanded range of coreceptors for infection, and that this adaptation is associated with progression to AIDS.


Assuntos
Infecções por HIV/imunologia , Receptores Virais/metabolismo , Contagem de Linfócito CD4 , Linhagem Celular , Progressão da Doença , Produtos do Gene env/metabolismo , Infecções por HIV/metabolismo , HIV-1/isolamento & purificação , Humanos
12.
Br J Anaesth ; 104(5): 563-76, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20299348

RESUMO

BACKGROUND: The aims of this study were to investigate the effectiveness, safety, pharmacokinetics, and pharmacodynamics of microemulsion propofol, Aquafol (Daewon Pharmaceutical Co., Ltd, Seoul, Republic of Korea). METHODS: In total, 288 patients were randomized to receive 1% Aquafol or 1% Diprivan (AstraZeneca, London, UK) (n=144, respectively). A 30 mg test dose of propofol was administered i.v. over 2 s for assessing injection pain. Subsequently, a bolus of propofol 2 mg kg(-1) (-30 mg) was administered. Anaesthesia was maintained with a variable rate infusion of propofol and a target-controlled infusion of remifentanil. Mean infusion rates of both formulations and times to loss of consciousness (LOC) and recovery of consciousness (ROC) were recorded. Adverse events and pharmacokinetic and pharmacodynamic characteristics were evaluated. RESULTS: Mean infusion rate of Aquafol was not statistically different from that of Diprivan (median: 6.2 vs 6.3 mg kg(-1) h(-1)). Times to LOC and ROC were slightly prolonged in Aquafol (median: 21 vs 18 s, 12.3 vs 10.8 min). Aquafol showed similar incidence of adverse events to Diprivan. Aquafol (vs Diprivan caused more severe (median VAS: 72.0 vs 11.5 mm) and frequent (81.9 vs 29.2%) injection pain. The dose-normalized AUC(last) of Aquafol and Diprivan was 0.71 (0.19) and 0.74 (0.20) min litre(-1). The V(1) of both formulations were proportional to lean body mass. Sex was a significant covariate for k(12) and Ce(50) of Aquafol, and for k(e0) of Diprivan. CONCLUSIONS: Aquafol was as effective and safe as Diprivan, but caused more severe and frequent injection pain. Aquafol demonstrated similar pharmacokinetics to Diprivan.


Assuntos
Anestésicos Intravenosos/química , Propofol/química , Adulto , Analgésicos Opioides/administração & dosagem , Anestesia Intravenosa/métodos , Anestésicos Intravenosos/efeitos adversos , Anestésicos Intravenosos/sangue , Química Farmacêutica , Método Duplo-Cego , Esquema de Medicação , Procedimentos Cirúrgicos Eletivos , Emulsões , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dor/induzido quimicamente , Medição da Dor/métodos , Dor Pós-Operatória/prevenção & controle , Náusea e Vômito Pós-Operatórios/induzido quimicamente , Propofol/efeitos adversos , Propofol/sangue
13.
Science ; 259(5099): 1288-93, 1993 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-8446897

RESUMO

The x-ray crystal structure of a peptide designed to form a double-stranded parallel coiled coil shows that it is actually a triple-stranded coiled coil formed by three alpha-helices. Unlike the designed parallel coiled coil, the helices run up-up-down. The structure is stabilized by a distinctive hydrophobic interface consisting of eight layers. As in the design, each alpha-helix in the coiled coil contributes one leucine side chain to each layer. The structure suggests that hydrophobic interactions are a dominant factor in the stabilization of coiled coils. The stoichiometry and geometry of coiled coils are primarily determined by side chain packing in the solvent-inaccessible interior, but electrostatic interactions also contribute.


Assuntos
Proteínas de Ligação a DNA , Estrutura Secundária de Proteína , Proteínas de Saccharomyces cerevisiae , Sequência de Aminoácidos , Cristalografia , Proteínas Fúngicas/química , Proteínas Fúngicas/ultraestrutura , Ligação de Hidrogênio , Leucina/química , Modelos Moleculares , Dados de Sequência Molecular , Peptídeos/química , Proteínas Quinases/química , Proteínas Quinases/ultraestrutura , Tropomiosina/química , Tropomiosina/ultraestrutura
14.
Science ; 286(5446): 1939-42, 1999 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-10583954

RESUMO

The actin-binding protein gelsolin is involved in remodeling the actin cytoskeleton during growth-factor signaling, apoptosis, cytokinesis, and cell movement. Calcium-activated gelsolin severs and caps actin filaments. The 3.4 angstrom x-ray structure of the carboxyl-terminal half of gelsolin (G4-G6) in complex with actin reveals the basis for gelsolin activation. Calcium binding induces a conformational rearrangement in which domain G6 is flipped over and translated by about 40 angstroms relative to G4 and G5. The structural reorganization tears apart the continuous beta sheet core of G4 and G6. This exposes the actin-binding site on G4, enabling severing and capping of actin filaments to proceed.


Assuntos
Actinas/metabolismo , Gelsolina/química , Gelsolina/metabolismo , Actinas/química , Sítios de Ligação , Cristalografia por Raios X , Ligação de Hidrogênio , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
15.
Science ; 294(5547): 1679-84, 2001 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-11721045

RESUMO

We determined a crystal structure of bovine Arp2/3 complex, an assembly of seven proteins that initiates actin polymerization in eukaryotic cells, at 2.0 angstrom resolution. Actin-related protein 2 (Arp2) and Arp3 are folded like actin, with distinctive surface features. Subunits ARPC2 p34 and ARPC4 p20 in the core of the complex associate through long carboxyl-terminal alpha helices and have similarly folded amino-terminal alpha/beta domains. ARPC1 p40 is a seven-blade beta propeller with an insertion that may associate with the side of an actin filament. ARPC3 p21 and ARPC5 p16 are globular alpha-helical subunits. We predict that WASp/Scar proteins activate Arp2/3 complex by bringing Arp2 into proximity with Arp3 for nucleation of a branch on the side of a preexisting actin filament.


Assuntos
Citoesqueleto de Actina/química , Citoesqueleto de Actina/metabolismo , Actinas/química , Actinas/metabolismo , Proteínas do Citoesqueleto , Proteína 2 Relacionada a Actina , Proteína 3 Relacionada a Actina , Trifosfato de Adenosina/metabolismo , Animais , Bovinos , Cristalografia por Raios X , Substâncias Macromoleculares , Modelos Biológicos , Modelos Moleculares , Músculo Esquelético , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Subunidades Proteicas , Eletricidade Estática , Timo
16.
Trends Biochem Sci ; 24(9): 345-9, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10470033

RESUMO

Electrical excitability is a fundamental property of the neuromuscular systems of metazoans. The varied response of neurons to electrical excitation is largely accounted for by a diverse set of voltage-gated potassium (KV) channels in the excitable membrane. The complete structure of a KV channel is not yet available. However, recent structural biological experiments have begun to provide new insight into how specific KV channels are formed and regulated, and how they function and interact with other proteins. In particular, the selectivity of KV channels for K+ and suggestions as to how these structural elements might assemble into a functional KV channel are discussed.


Assuntos
Citoplasma/metabolismo , Ativação do Canal Iônico/fisiologia , Canais de Potássio/química , Canais de Potássio/metabolismo , Animais , Caenorhabditis elegans/genética , Eletrofisiologia , Modelos Moleculares , Canais de Potássio/genética , Conformação Proteica , Especificidade por Substrato
17.
Mol Cell Biol ; 13(5): 2644-54, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8474435

RESUMO

In vitro conditions are reported under which an EcoRI-HpaI fragment of the Saccharomyces cerevisiae ribosomal gene spacer will enhance transcription from an adjacent RNA polymerase I promoter. Enhancement is largely independent of orientation and distance and is proportional to copy number. Mapping experiments reveal that two separate regions of the EcoRI-HpaI fragment are independently capable of promoter stimulation. These regions appear to correspond to elements which have been shown by previous workers to cause enhancement in vivo. Using the detergent Sarkosyl to limit the number of rounds of transcription from each promoter, we found that the degree of enhancement is similar whether one or many rounds of transcription occur. This finding supports a model in which the enhancer increases the number of stable promoter complexes but does not alter the loading of polymerase on an active promoter. Once the stable promoter complex is formed, the enhancer can be physically severed from the promoter with no loss of enhancement. Likewise, the upstream activation region of the promoter can be severed from the core promoter domain once the stable complex has been formed. These results are interpreted to mean that the enhancer functions only to assist stable complex formation and, once that is accomplished, the enhancer is dispensable.


Assuntos
DNA Ribossômico/genética , Elementos Facilitadores Genéticos , RNA Polimerase I/genética , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Sequência de Bases , Cromossomos Fúngicos , Desoxirribonuclease EcoRI , Desoxirribonucleases de Sítio Específico do Tipo II , Íntrons , Cinética , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Mapeamento por Restrição , Regiões Terminadoras Genéticas , Transcrição Gênica
18.
Curr Opin Struct Biol ; 10(4): 456-61, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10981635

RESUMO

Since the determination of the structure of a bacterial potassium channel, the ion channel community has managed to gain momentum in the quest for a complete picture. The information is coming at a steady flow, on a domain by domain basis. Recent discoveries are starting to reveal clues to the complex manner in which potassium channels show enormous diversity of function and also to their methods of regulation. Currently, the structures of four domains are known, with the most recent addition being the Kvbeta structure. As efforts continue in the study of the transmembrane domains, especially the voltage-sensing apparatus, there has been a new realization with respect to the identification and role of the cytoplasmic domains in protein-protein interactions in particular. An additional discovery, considerably aided by recent genomic analysis, is that potassium channels comprising subunits with two pore regions and four transmembrane helices combined in a dimeric fashion are abundant and are probable targets for local anesthetics.


Assuntos
Canais de Potássio , Animais , Humanos , Ativação do Canal Iônico , Transporte de Íons , Canais de Potássio/química , Canais de Potássio/metabolismo , Conformação Proteica , Relação Estrutura-Atividade
19.
Theriogenology ; 68(2): 265-75, 2007 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-17559922

RESUMO

The present study examined the expression pattern of oxygen (O(2)) and stress-responsive gene transcripts at various preimplantation developmental stages of in vitro produced (IVP) and in vivo derived (IVD) bovine embryos. Embryos were produced in vitro from oocytes matured, fertilized and cultured in synthetic oviductal fluid (SOF) medium under low (5%) and high (20%) O(2) concentrations. In vivo embryos were derived from 18 superovulated and artificially inseminated cows. In IVP and IVD groups, embryos were collected at 2-, 4-, 8-, 16-cell morula and blastocyst stages at specific time points for gene expression analysis. The cleavage rates (69.8+/-4.8%) did not differ significantly, but blastocyst rates were significantly higher (28.5+/-3.7%) in low O(2) than those in high O(2) group (18.7+/-3.9%). Mean cell number in low O(2) (145+/-12) and high O(2) (121+/-73) IVP blastocyst were lower (P<0.05) than those of IVD blastocyst (223+/-25). The ICM ratio of IVD blastocyst (26+/-4) was lower (P<0.05) than that of IVP embryos under 5% O(2) (33+/-5) and 20% O(2) (34+/-4) concentrations, respectively. Using real time PCR, for the set of target transcripts (Glut1, Glut5, Sox, G6PD, MnSOD, PRDX5, NADH and Hsp 70.1) analyzed, there were differences in the mRNA expression pattern at 2-, 4-, 8-, 16-cell morula and Day 7 blastocyst stages between the two embryo sources. It can be concluded that, although in vitro bovine embryo culture in SOF medium under low (5%) O(2) concentration provided a more conducive environment in terms of blastocyst formation; differences in the total cell number and gene expression pattern between the IVP and IVD embryos reflected the effect of O(2) concentration.


Assuntos
Blastocisto/metabolismo , Bovinos/embriologia , Desenvolvimento Embrionário/genética , Regulação da Expressão Gênica no Desenvolvimento , Estresse Oxidativo/genética , Oxigênio/metabolismo , RNA Mensageiro/metabolismo , Animais , Antioxidantes/metabolismo , Transporte Biológico/genética , Bovinos/genética , Técnicas de Cultura Embrionária , Glucose/metabolismo , Mitocôndrias/metabolismo
20.
J Thromb Haemost ; 15(6): 1095-1102, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28339142

RESUMO

Essentials Antiangiogenic drugs are indicated as therapies for hereditary hemorrhagic telangiectasia. We interrogated the response to four antiangiogenic drugs for anemia and intestinal bleeding. Sorafenib and a pazopanib analog significantly improved while erlotinib worsened anemia. Some oral antiangiogenic drugs were effective in reducing intestinal bleeding. SUMMARY: Background Epistaxis and gastrointestinal (GI) tract hemorrhages are common symptoms of aged hereditary hemorrhagic telangiectasia (HHT) patients that result in anemia. Clinical as well as animal studies have suggested that vascular endothelial growth factor (VEGF) neutralizing antibodies lessen hemorrhage associated with adult-onset arteriovenous malformations (AVMs). Objectives The goal of this study is to evaluate potential therapeutic effects of oral delivery of four antiangiogenic tyrosine-kinase inhibitors (TKIs) in the development of adult-onset AVMs in a murine model of HHT. Methods An adult activin receptor-like kinase 1 (Alk1)-inducible knockout (iKO) model was utilized to evaluate the effect of oral administration of sorafenib, sunitinib, erlotinib and a pazopanib analog (GW771806) on hemoglobin level, GI hemorrhages and formation of wound-induced skin AVMs. Results and Conclusions Sorafenib and GW771806 significantly improved, yet erlotinib worsened, anemia and GI-bleeding in the Alk1-iKO model. However, none of these TKIs appeared to be effective for inhibiting the development of wound-induced skin AVMs. Taken together, these results suggest that oral delivery of antiangiogenic TKIs is selectively more effective for GI bleeding than mucocutaneous AVMs, and it may provide an experimental basis for selective therapeutic options depending on the symptoms of HHT.


Assuntos
Inibidores da Angiogênese/uso terapêutico , Inibidores de Proteínas Quinases/uso terapêutico , Telangiectasia Hemorrágica Hereditária/tratamento farmacológico , Telangiectasia Hemorrágica Hereditária/genética , Receptores de Ativinas Tipo I/metabolismo , Receptores de Activinas Tipo II , Administração Oral , Administração Tópica , Anemia/tratamento farmacológico , Anemia/genética , Animais , Malformações Arteriovenosas , Modelos Animais de Doenças , Cloridrato de Erlotinib/administração & dosagem , Hemorragia Gastrointestinal , Hemoglobinas/análise , Processamento de Imagem Assistida por Computador , Indazóis/administração & dosagem , Camundongos , Camundongos Knockout , Niacinamida/administração & dosagem , Niacinamida/análogos & derivados , Compostos de Fenilureia/administração & dosagem , Pirimidinas/administração & dosagem , Pele/irrigação sanguínea , Sorafenibe , Sulfonamidas/administração & dosagem , Sulfonas/administração & dosagem , Tirosina/química , Fator A de Crescimento do Endotélio Vascular/metabolismo , Cicatrização
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