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1.
Gels ; 9(8)2023 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-37623057

RESUMO

In this paper, we report the synthesis of acrylamide hydrogels (net-AAm) reinforced with cellulose nanocrystals (CNCs) using gamma radiation, a powerful tool to obtain crosslinked polymers without the use of chemical initiators and crosslinking agents. Some slight changes in the chemical structure and crystallinity of CNCs took place during gamma irradiation without affecting the nanofiller function. In fact, cellulose nanocrystals had a notable influence over the swelling and mechanical properties on the reinforced hydrogels (net-AAm/CNC), obtaining more rigid material since the Young compression modulus increased from 11 kPa for unreinforced net-AAm to 30 kPa for net-AAm/CNC (4% w/w). Moreover, the studies of retention and release of ciprofloxacin (Cx), a quinolone antibiotic drug, showed that reinforced hydrogels were able to load large amounts of ciprofloxacin (1.2-2.8 mg g-1) but they distributed 100% of the drug very quickly (<100 min). Despite this, they exhibited better mechanical properties than the control sample, allowing their handling, and could be used as wound dressings of first response because they can absorb the exudate and at the same time deliver an antibiotic drug directly over the injury.

2.
Polymers (Basel) ; 13(16)2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34451181

RESUMO

In this study, we carried out the synthesis of a thermo- and pH-sensitive binary graft, based on N-vinylcaprolactam (NVCL) and pH sensitive acrylic acid (AAc) monomers, onto chitosan gels (net-CS) by ionizing radiation. Pre-oxidative irradiation and direct methods were examined, and materials obtained were characterized by FTIR-ATR, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and swelling tests (equilibrium swelling time, critical pH, and temperature). The best synthesis radiation method was the direct method, which resulted in the maximum grafting percentages (~40%) at low doses (10-12 kGy). The main goal of this study was the comparison of the swelling behavior and physicochemical properties of net-CS with those of the binary system (net-CS)-g-NVCL/AAc with the optimum grafting percentage (~30%). This produced a material that showed an upper critical solution temperature (UCST) of 33.5 °C and a critical pH value of 3.8, indicating the system is more hydrophilic at higher temperatures and low pH values. Load and release studies were carried out using diclofenac. The grafted system (32%) was able to load 19.3 mg g-1 of diclofenac and release about 95% within 200 min, in comparison to net-CS, which only released 80% during the same period. When the grafted system was protonated before diclofenac loading, it loaded 27.6 mg g-1. However, the drug was strongly retained in the material by electrostatic interactions and only released about 20%.

3.
Head Neck ; 41(5): 1153-1160, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30620438

RESUMO

Few protocols have been published for the dental management of patients with head and neck cancer to prevent complications from head and neck radiation therapy. Radiation therapy not only affects the tumor cells targeted, but also the dentition, bone, salivary gland, and oral soft tissue structures. A comprehensive dental evaluation prior to head and neck radiation therapy can help prevent many complications. The following clinical guidelines were established by a workgroup of oral health providers within the Department of Veterans Affairs. This workgroup focused on developing a set of recommendations regarding dental care prior to the initiation of head and neck radiation therapy based on the best clinical evidence and expert consensus. A systematic algorithm was developed for the evaluation including pre-exam data gathering, examination, education, and treatment, followed by maintenance and postradiation dental follow-up. This document is evidence-based, patient-centered, consistent with accepted practices of care and safety, and in accordance with applicable statutes and regulations.


Assuntos
Assistência Odontológica/normas , Neoplasias de Cabeça e Pescoço/radioterapia , Diagnóstico Bucal , Humanos , Higiene Bucal , Educação de Pacientes como Assunto/normas , Doenças Dentárias/prevenção & controle , Doenças Dentárias/terapia
4.
J Pept Sci ; 24(1)2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29231280

RESUMO

The RPAR peptide, a prototype C-end Rule (CendR) sequence that binds to neuropilin-1 (NRP-1), has potential therapeutic uses as internalization trigger in anticancer nanodevices. Recently, the functionalization of gold nanoparticles with CendR peptides has been proved to be a successful strategy to target the NRP-1 receptor in prostate cancer cells. In this work, we investigate the influence of two gold surface facets, (100) and (111), on the conformational preferences of RPAR using molecular dynamics simulations. Both clustering and conformational analyses revealed that the peptide backbone becomes very rigid upon adsorption onto gold, which is a very fast and favored process, the only flexibility being attributed to the side chains of the two Arg residues. Thus, the different components of RPAR tend to adopt an elongated shape, which is characterized by the pseudo-extended conformation of both the backbone and the Arg side chains. This conformation is very different from the already known bioactive conformation, indicating that RPAR is drastically affected by the substrate. Interestingly, the preferred conformations of the peptide adsorbed onto gold facets are not stabilized by salt bridges and/or specific intramolecular hydrogen bonds, which represent an important difference with respect to the conformations found in other environments (e.g. the peptide in solution and interacting with NRP-1 receptor). However, the conformational changes induced by the substrate are not detrimental for the use of gold nanoparticles as appropriate vehicles for the transport and targeted delivery of the RPAR. Thus, once their high affinity for the NRP-1 receptor induces the targeted delivery of the elongated peptide molecules from the gold nanoparticles, the lack of intramolecular interactions facilitates their evolution towards the bioactive conformation, increasing the therapeutic efficacy of the peptide.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Simulação de Dinâmica Molecular , Peptídeos/química , Adsorção , Propriedades de Superfície
5.
Rev Panam Salud Publica ; 42: e101, 2018.
Artigo em Espanhol | MEDLINE | ID: mdl-31093129

RESUMO

OBJECTIVE: To determine the ability of cigarette-pack warning labels, of the minimum size required by the World Health Organization, to capture the attention of smokers and nonsmokers. METHODS: In this study, 30 smokers and 30 nonsmokers completed a dot-probe task in which they simultaneously observed images of cigarette packs split in two: the top contained the cigarette brand and the bottom contained the warning label. During the task, brain activity was recorded through two event-related potentials of the negative-polarity type--the potential that occurs in the posterior-contralateral zone approximately 200 ms after a stimulus (N2pc) and the sustained posterior contralateral negativity (SPCN) response--which are indicators of early and sustained attention. RESULTS: In both groups, a greater amplitude of N2pc and SPCN potentials was found for the part of the pack containing the cigarette brand. However, during the dot-probe task, reaction times were shorter for the warning label. CONCLUSIONS: These results suggest that, initially, attention is focused on the cigarette brand, and only then on the warning label. The inability of warning labels to capture early-phase attention decreases their effectiveness, especially in smokers. We suggest that warning labels be enlarged to facilitate increased attention response.


OBJETIVO: Determinar a capacidade das tarjas de advertência com o tamanho mínimo exigido pela Organização Mundial da Saúde (OMS) de atrair a atenção de fumantes e não fumantes. MÉTODOS: A amostra do estudo consistiu de 30 fumantes e 30 não fumantes que foram testados com uma tarefa de sondagem (dot-probe task) em que tiveram de observar simultaneamente imagens de um maço de cigarro dividido ao meio: a parte superior continha a marca do cigarro e a parte inferior continha a tarja de advertência. Durante o teste, foi registrada a atividade cerebral com a análise de potenciais evocados relacionados a eventos do tipo potencial negativo que ocorre em cerca de 200 ms na área posterior contralateral ao estímulo (N2pc) e da ocorrência de negatividade contralateral posterior sustentada (SPCN, em inglês), que são indicadores de atenção mais rápida e sustentada. RESULTADOS: Em ambos os grupos de participantes foi observada maior amplitude dos potenciais N2pc e SPCN na parte do maço que continha a marca. Porém, o tempo de reação na tarefa de sondagem foi menor diante da tarja de advertência. CONCLUSÕES: Os resultados deste estudo sugerem que, ao início, a atenção é dirigida à marca do cigarro e depois à tarja de advertência. A incapacidade da tarja de advertência de atrair a atenção nas primeiras fases diminui sua eficácia, sobretudo entre os fumantes. Recomenda-se aumentar o tamanho das tarjas de advertência para estimular um incremento na resposta de atenção.

6.
Rev. panam. salud pública ; 42: e101, 2018. tab, graf
Artigo em Espanhol | LILACS | ID: biblio-961716

RESUMO

RESUMEN Objetivo Establecer la capacidad que tienen las etiquetas de advertencia con el tamaño mínimo exigido por la Organización Mundial de la Salud para capturar la atención en fumadores y no fumadores. Métodos En el estudio se incluyeron 30 fumadores y 30 no fumadores, quienes realizaron una prueba de detección del punto (dot-probe) en la cual observaron, de manera simultánea, imágenes de cajetillas de cigarrillo divididas en dos: la parte superior contenía la marca de los cigarrillos y la parte inferior contenía la etiqueta de advertencia. Durante la tarea, se registró la actividad cerebral a través de los potenciales relacionados a eventos del tipo potencial negativo que ocurre aproximadamente a los 200 ms en la zona posterior contralateral al estímulo (N2pc) y negatividad contralateral posterior sostenida (SPCN, por sus siglas en inglés), los cuales son indicadores de atención temprana y sostenida. Resultados En ambos grupos se encontró mayor amplitud de los potenciales N2pc y SPCN hacia la porción de la cajetilla que contiene la marca de cigarrillos. Sin embargo, el tiempo de reacción fue menor ante la etiqueta de advertencia en la tarea dot-probe. Conclusiones Los resultados sugieren que, al inicio, la atención se dirige hacia la marca de los cigarrillos y luego hacia la etiqueta de advertencia. La incapacidad de las etiquetas de advertencia para capturar la atención en las primeras fases disminuye su eficacia, sobre todo en fumadores. Se sugiere aumentar el tamaño de las etiquetas de advertencia para favorecer un incremento en la respuesta de atención.


ABSTRACT Objective To determine the ability of cigarette-pack warning labels, of the minimum size required by the World Health Organization, to capture the attention of smokers and nonsmokers. Methods In this study, 30 smokers and 30 nonsmokers completed a dot-probe task in which they simultaneously observed images of cigarette packs split in two: the top contained the cigarette brand and the bottom contained the warning label. During the task, brain activity was recorded through two event-related potentials of the negative-polarity type--the potential that occurs in the posterior-contralateral zone approximately 200 ms after a stimulus (N2pc) and the sustained posterior contralateral negativity (SPCN) response--which are indicators of early and sustained attention. Results In both groups, a greater amplitude of N2pc and SPCN potentials was found for the part of the pack containing the cigarette brand. However, during the dot-probe task, reaction times were shorter for the warning label. Conclusions These results suggest that, initially, attention is focused on the cigarette brand, and only then on the warning label. The inability of warning labels to capture early-phase attention decreases their effectiveness, especially in smokers. We suggest that warning labels be enlarged to facilitate increased attention response.


RESUMO Objetivo Determinar a capacidade das tarjas de advertência com o tamanho mínimo exigido pela Organização Mundial da Saúde (OMS) de atrair a atenção de fumantes e não fumantes. Métodos A amostra do estudo consistiu de 30 fumantes e 30 não fumantes que foram testados com uma tarefa de sondagem (dot-probe task) em que tiveram de observar simultaneamente imagens de um maço de cigarro dividido ao meio: a parte superior continha a marca do cigarro e a parte inferior continha a tarja de advertência. Durante o teste, foi registrada a atividade cerebral com a análise de potenciais evocados relacionados a eventos do tipo potencial negativo que ocorre em cerca de 200 ms na área posterior contralateral ao estímulo (N2pc) e da ocorrência de negatividade contralateral posterior sustentada (SPCN, em inglês), que são indicadores de atenção mais rápida e sustentada. Resultados Em ambos os grupos de participantes foi observada maior amplitude dos potenciais N2pc e SPCN na parte do maço que continha a marca. Porém, o tempo de reação na tarefa de sondagem foi menor diante da tarja de advertência. Conclusões Os resultados deste estudo sugerem que, ao início, a atenção é dirigida à marca do cigarro e depois à tarja de advertência. A incapacidade da tarja de advertência de atrair a atenção nas primeiras fases diminui sua eficácia, sobretudo entre os fumantes. Recomenda-se aumentar o tamanho das tarjas de advertência para estimular um incremento na resposta de atenção.


Assuntos
Humanos , Rotulagem de Produtos , Nicotiana , Política de Saúde
7.
Carbohydr Polym ; 155: 303-312, 2017 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-27702516

RESUMO

The aim of this study was to synthesize chitosan hydrogels, in macro- and nano-size, grafted with N-vinylcaprolactam (NVCL) using gamma radiation, and evaluate their potential application as a drug delivery system, using 5-fluorouracil (5-FU) as a model drug. The effect of dose and monomer concentration in the grafting process was studied, and the materials were characterized by FTIR, TGA, DLS, SEM and AFM. Higher grafting percentages were observed for the nanogels system. Although both the grafted macro- and nanogels, (net-CS)-g-NVCL, showed a response to pH (4.75) and temperature (31-33°C), the nanogels showed a better swelling response to both stimuli because of their higher surface area. Both systems were able to load 5-FU in small amounts (2-3.5mgg-1) and the release was sustained for more than 12h, showing that the modified macro and nanogels can be a potential alternative for the administration of drugs.

8.
HIV Clin Trials ; 16(2): 57-65, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25874992

RESUMO

BACKGROUND AND OBJECTIVES: Cardiovascular disease is a major concern in HIV-infected patients. Lifetime risk estimations use the risk of developing it over the course of remaining lifetime, and are useful in communicating this risk to young patients. We aim to describe the prevalence of cardiovascular risk factors among a representative sample of HIV-infected subjects under antiretroviral therapy in Spain, and to estimate their lifetime risk of cardiovascular disease. METHODS: Cross-sectional survey about cardiovascular risk factors in 10 HIV units across Spain. Lifetime risk assessed according to Barry was classified in two major categories: low and high lifetime risk. RESULTS: We included 895 subjects, 72% men, median age 45.7 years; median CD4 lymphocyte count 598 cells/µl, median time since HIV diagnosis 11 years, median time on antiretroviral treatment 6.3 years, 87% had undetectable HIV viral load. Tobacco smoking was the most frequent risk factor (54%), followed by dyslipidemia (48.6%) and hypertension (38.6%). Estimated 10-year coronary risk (Framingham/Regicor Risk Score) risk was low ( < 5%) in 78% of the patients, and intermediate (5-10%) in 20%. Lifetime risk estimation showed a high risk profile for 71.4% of the population studied, which was associated with increasing age, prolonged antiretroviral therapy and patient's place of origin. CONCLUSIONS: Modifiable cardiovascular risk factors in this population are very common. There are significant disparities between the low 10-year risk estimated with the Framingham/Regicor score and the higher lifetime risk in HIV patients on antiretroviral therapy. A more aggressive management of modifiable cardiovascular risk factors in these patients seems advisable.


Assuntos
Antirretrovirais/uso terapêutico , Doenças Cardiovasculares/epidemiologia , Infecções por HIV/epidemiologia , Adulto , Idoso , Contagem de Linfócito CD4 , Doenças Cardiovasculares/complicações , Estudos Transversais , Dislipidemias , Feminino , Infecções por HIV/complicações , Infecções por HIV/tratamento farmacológico , Humanos , Hipertensão , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , Espanha/epidemiologia , Fumar Tabaco
9.
Acta biol. colomb ; 20(1): 109-116, ene.-abr. 2015. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-734905

RESUMO

Los marcadores genéticos del pelaje y malformaciones óseas han permitido caracterizar el perfil genético de más de 400 poblaciones del gato doméstico alrededor del mundo. Hace 15 años se estableció dicho perfil en la ciudad de Cali (Colombia). En este estudio se determinó si el norte y sur de Cali se comportan como subpoblaciones y se comparó el perfil total con el estudio pasado. Se encontró una disminución de la frecuencia alélica de a (no-agouti) y d (dilution), pero un aumento en cinco, especialmente en l (longhair) y c s (siamese). Dichas diferencias pueden atribuirse a la selección humana de características más atractivas y por el flujo génico resultante del crecimiento demográfico de la ciudad, lo que explicaría también el primer reporte de los alelos inhibitor y ticked abyssinian. Se evaluó el equilibrio Hardy-Weinberg para el norte, sur y las dos zonas juntas, usando los loci white spotting y orange, encontrándose desequilibrio en este último para las tres zonas evaluadas debido a un déficit de heterocigotos. Norte y sur se dividieron en dos, y cada sub-muestra presentó equilibrio Hardy-Weinberg, aunque las diferencias en las frecuencias alélicas y heterocigosidades resaltaron microestructura geográfica y una relación entre tiempo de fundación del barrio y heterocigosidad. Norte y sur resultaron ser una población y no subpoblaciones (F ST= 0,0004, D= 0,0017), al igual que las nueve poblaciones colombianas con las que se comparó la presente ciudad. Se sugiere realizar un análisis microgeográfico de flujo génico y la definición de posibles colonias de gatos en Cali.


The coat genetic markers and skeleton abnormalities have allowed characterize the profile from more than 400 domestic cat populations around the world. 15 years ago, that profile was established in the city of Cali (Colombia). In this study it was determined if north and south of the city are subpopulations and it was compared the total profile against past study. A decrease in allele frequency of a (non-agouti) and d (dilution) was found, but an increase of five alleles was found, especially in l (long hair) and c s (siamese). These differences could be attributed to human selection of more attractive characteristics and gene flow resulting from demographic growth city, which would also explain the first report of inhibitor and ticked abyssinian alleles. Hardy-Weinberg equilibrium was evaluated for the north, south and both areas together, using white spotting and orange loci, determining disequilibrium in orange for the three evaluated areas due to a heterozygotes deficit. North and south were divided into two, each sub-sample showed Hardy-Weinberg equilibrium, although allele frequencies and heterozygosities highlighted microgeographic structure and a relationship between founding time of the neighborhood and heterozygosity. North and south are a single population and aren´t subpopulations (F ST= 0,0004, D= 0,0017), as well as nine Colombian populations with which this city was compared. It is suggested to make a microgeographical gene flow analysis and the definition of possible cat colonies in Cali.

10.
J Vis Exp ; (62)2012 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-22525890

RESUMO

The development and maintenance of immunosuppressive CD4+ regulatory T cells (Tregs) contribute to the peripheral tolerance needed to remain in immunologic homeostasis with the vast amount of self and commensal antigens in and on the human body. Perturbations in the balance between Tregs and inflammatory conventional T cells can result in immunopathology or cancer. Although therapeutic injection of Tregs has been shown to be efficacious in murine models of colitis, type I diabetes, rheumatoid arthritis and graft versus host disease, several fundamental differences in human versus mouse Treg biology has thus far precluded clinical use. The lack of sufficient number, purity, stability and homing specificity of therapeutic Tregs necessitated a dynamic platform of human Treg development on which to optimize conditions for their ex vivo expansion. Here we describe a method for the differentiation of induced Tregs (iTregs) from a single human peripheral blood donor which can be broken down into four stages: isolation of peripheral blood mononuclear cells, magnetic selection of CD4+ T cells, in vitro cell culture and fluorescence activated cell sorting (FACS) of T cell subsets. Since the Treg signature transcription factor forkhead box P3 (FoxP3) is an activation-induced transcription factor in humans and no other unique marker exists, a combinatorial panel of markers must be used to identify T cells with suppressor activity. After six days in culture, cells in our system can be demarcated into naïve T cells, memory T cells or iTregs based on their relative expression of CD25 and CD45RA. As memory and naïve T cells have different reported polarization requirements and plasticities, pre-sorting of the initial T cell population into CD45RA(+) and CD45RO(+) subsets can be used to examine these discrepancies. Consistent with others, our CD25(Hi)CD45RA(-) iTregs express high levels of FoxP3, GITR and CTLA-4 and low levels of CD127. Following FACS of each population, resultant cells can be used in a suppressor assay which evaluates the relative ability to retard the proliferation of carboxyfluorescein succinimidyl ester (CFSE)-labeled autologous T cells.


Assuntos
Memória Imunológica , Linfócitos T Reguladores/imunologia , Técnicas de Cultura de Células , Diferenciação Celular/imunologia , Citometria de Fluxo/métodos , Corantes Fluorescentes/química , Humanos , Subunidade alfa de Receptor de Interleucina-2/biossíntese , Subunidade alfa de Receptor de Interleucina-2/imunologia , Antígenos Comuns de Leucócito/biossíntese , Antígenos Comuns de Leucócito/imunologia , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/imunologia , Magnetismo/métodos , Linfócitos T Reguladores/citologia
11.
Int J Mol Sci ; 11(10): 3906-21, 2010 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-21152308

RESUMO

Maxillofacial prostheses is a dental medicine specialty aimed at restoring anatomical facial defects caused by cancer, trauma or congenital malformations through an artificial device, which is commonly attached to the skin with the help of an adhesive. The purpose of our research was to develop a pressure-sensitive adhesive (PSA) based on acrylic monomers, characterizing and determining its drying kinetics, that is to say the time it takes to lose 50 to 90% of its moisture. The adhesive synthesis was realized by means of emulsion polymerization; the composition of formulations was: (AA-MMA-EA) and (AA-MMA-2EHA) with different molar ratios. The formulation based on (AA-MMA-2EHA) with 50 w% of solids, presented good adhesive properties such as tack, bond strength, and short drying time. We propose this formulation as a PSA, because it offers an alternative for systemically compromised patients, by less irritation compared to organic solvent-based adhesives.


Assuntos
Adesivos/síntese química , Prótese Maxilofacial , Metilmetacrilatos/síntese química , Emulsões/síntese química , Polimerização
12.
J Phys Chem B ; 113(22): 7879-89, 2009 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-19432404

RESUMO

A new amino acid has been designed as a replacement for arginine (Arg, R) to protect the tumor-homing pentapeptide CREKA (Cys-Arg-Glu-Lys-Ala) from proteases. This amino acid, denoted (Pro)hArg, is characterized by a proline skeleton bearing a specifically oriented guanidinium side chain. This residue combines the ability of Pro to induce turn-like conformations with the Arg side-chain functionality. The conformational profile of the CREKA analogue incorporating this Arg substitute has been investigated by a combination of simulated annealing and molecular dynamics. Comparison of the results with those previously obtained for the natural CREKA shows that (Pro)hArg significantly reduces the conformational flexibility of the peptide. Although some changes are observed in the backbone...backbone and side-chain...side-chain interactions, the modified peptide exhibits a strong tendency to accommodate turn conformations centered at the (Pro)hArg residue and the overall shape of the molecule in the lowest energy conformations characterized for the natural and the modified peptides exhibit a high degree of similarity. In particular, the turn orients the backbone such that the Arg, Glu, and Lys side chains face the same side of the molecule, which is considered important for bioactivity. These results suggest that replacement of Arg by (Pro)hArg in CREKA may be useful in providing resistance against proteolytic enzymes while retaining conformational features which are essential for tumor-homing activity.


Assuntos
Substituição de Aminoácidos , Arginina/química , Oligopeptídeos/química , Prolina/química , Sequência de Aminoácidos , Simulação por Computador , Guanidina/química , Modelos Moleculares , Conformação Proteica
13.
J Phys Chem B ; 112(44): 14045-55, 2008 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-18842022

RESUMO

Quantum mechanical calculations have been used to investigate how the incorporation of an amino group to the Cbeta- or Cgamma-positions of the pyrrolidine ring affects the intrinsic conformational properties of the proline. Specifically, a conformational study of the N-acetyl-N'-methylamide derivatives of four isomers of aminoproline, which differ not only in the beta- or gamma-position of the substituent but also in its cis or trans relative disposition, has been performed. To further understand the role of the intramolecular hydrogen bonds between the backbone carbonyl groups and the amino side group, a conformational study was also performed on the corresponding four analogues of (dimethylamino)proline. In addition, the effects of solvation on aminoproline and (dimethylamino)proline dipeptides have been evaluated using a self-consistent reaction field model, and considering four different solvents (carbon tetrachloride, chloroform, methanol and water). Results indicate that the incorporation of the amino substituent into the pyrrolidine ring affects the conformational properties, with backbone...side chain intramolecular hydrogen bonds detected when it is incorporated in a cis relative disposition. In general, the incorporation of the amino side group tends to stabilize those structures where the peptide bond involving the pyrrolidine nitrogen is arranged in cis. The aminoproline isomer with the substituent attached to the Cgamma-position with a cis relative disposition is the most stable in the gas phase and in chloroform, methanol and water solutions. Replacement of the amino side group by the dimethylamino substituent produces significant changes in the potential energy surfaces of the four investigated (dimethylamino)proline-containing dipeptides. Thus, these changes affect not only the number of minima, which increases considerably, but also the backbone and pseudorotational preferences. In spite of these effects, comparison of the conformational preferences, i.e., the more favored conformers, calculated for different isomers of aminoproline and (dimethylamino)proline dipeptides showed a high degree of consistency for the two families of compounds.


Assuntos
Conformação Molecular , Prolina/análogos & derivados , Gases/química , Metilação , Modelos Moleculares , Peptídeos/química , Prolina/química
14.
J Phys Chem B ; 112(29): 8692-700, 2008 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-18588341

RESUMO

Recently, a potentially powerful strategy based on phage-display libraries has been presented to target tumors via homing peptides attached to nanoparticles. The Cys-Arg-Glu-Lys-Ala (CREKA) peptide sequence has been identified as a tumor-homing peptide that binds to clotted plasmas proteins present in tumor vessels and interstitium. The aim of this work consists of mapping the conformational profile of CREKA to identify the bioactive conformation. For this purpose, a conformational search procedure based on modified simulated annealing combined with molecular dynamics was applied to three systems that mimic the experimentally used conditions: (i) the free peptide; (ii) the peptide attached to a nanoparticle; and (iii) the peptide inserted in a phage display protein. In addition, the free peptide was simulated in an ionized aqueous solution environment, which mimics the ionic strength of the physiological medium. Accessible minima of all simulated systems reveal a multiple interaction pattern involving the ionized side chains of Arg, Glu, and Lys, which induces a beta-turn motif in the backbone observed in all simulated CREKA systems.


Assuntos
Proteínas de Neoplasias/química , Oligopeptídeos/química , Fragmentos de Peptídeos/química , Sequência de Aminoácidos , Arginina/química , Arginina/metabolismo , Sítios de Ligação , Simulação por Computador , Ácido Glutâmico/química , Ácido Glutâmico/metabolismo , Lisina/química , Lisina/metabolismo , Dados de Sequência Molecular , Nanopartículas/química , Proteínas de Neoplasias/metabolismo , Oligopeptídeos/metabolismo , Fragmentos de Peptídeos/metabolismo , Estrutura Secundária de Proteína , Soluções/química , Termodinâmica , Fatores de Tempo , Água/química
15.
Ginecol. obstet. Méx ; 62(6): 157-60, jun. 1994. tab
Artigo em Espanhol | LILACS | ID: lil-198908

RESUMO

Mediante un estudio prospectivo realizado en el Hospital de Gineco-Obstetricia del Centro Médico León del Instituto Mexicano del Seguro Social, se estudiaron 60 pacientes con diagnóstico de embarazo ectópico confirmado por laparotomía, con el objetivo de describir los hallazgos clínicos y ultrasonográficos informados en estas pacientes. La edad promedio fue de 28.17 años. Las mujeres multigestas fueron más afectadas por esta patología (80 por ciento). Los antecedentes obstétricos más frecuentes fueron el legrado uterino (26.6 por ciento) y el uso previo de dispositivos intrauterino (23.3 por ciento). El síntoma clínico dolor pélvico fue referido en 48 pacientes (80 por ciento). Los datos de repercución hemodinámica solo se presentaron en 21.6 por ciento de los casos. Los hallazgos ultrasonográficos fueron referidos en la mayoría de las pacientes, predominando los datos masa anexial heterogénea (91.6 por ciento) y líquido libre en cavidad pélvica (61.6 por ciento). La variable masa anexial heterogénea tuvo una relación lineal con la confirmación del diagnóstico y obtuvo un coeficiente de correlación R = 0.99 (P < 0.01). Los hallazgos ultrasonográficos obtenidos con transductor transvaginal son similares a los obtenidos con transductor transvaginal son similares a los obtenidos mediante técnica transabdominal y se consideran técnicas complementarias. Se concluye que el ultrasonido continuá representando una importante ayuda en el protocolo de diagnóstico del embarazo ectópico


Assuntos
Humanos , Feminino , Gravidez , Adulto , Gravidez Ectópica/diagnóstico , Ultrassonografia Pré-Natal/métodos
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