RESUMO
Magnetite nanoparticles (MNPs) have attracted basic and applied research due to their immense potential to enable applications in fields as varied as drug delivery and bioremediation. Conventional synthesis schemes led to wide particle size distributions and inhomogeneous morphologies and crystalline structures. This has been attributed to the inability to control nucleation and growth processes under the conventional conditions of bulk batch processes. Here, we attempted to address these issues by scaling down the synthesis process aided by microfluidic devices, as they provide highly controlled and stable mixing patterns. Accordingly, we proposed three micromixers with different channel configurations, namely, serpentine, triangular, and a 3D arrangement with abrupt changes in fluid direction. The micromixers were first studied in silico, aided by Comsol Multiphysics® to investigate the obtained mixing patterns, and consequently, their potential for controlled growth and the nucleation processes required to form MNPs of uniform size and crystalline structure. The devices were then manufactured using a low-cost approach based on polymethyl methacrylate (PMMA) and laser cutting. Testing the micromixers in the synthesis of MNPs revealed homogeneous morphologies and particle size distributions, and the typical crystalline structure reported previously. A life cycle assessment (LCA) analysis for the devices was conducted in comparison with conventional batch co-precipitation synthesis to investigate the potential impacts on water and energy consumption. The obtained results revealed that such consumptions are higher than those of the conventional process. However, they can be reduced by conducting the synthesis with reused micromixers, as new PMMA is not needed for their assembly prior to operation. We are certain that the proposed approach represents an advantageous alternative to co-precipitation synthesis schemes, in terms of continuous production and more homogeneous physicochemical parameters of interest such as size, morphologies, and crystalline structure. Future work should be directed towards improving the sustainability indicators of the micromixers' manufacturing process.
RESUMO
Antimicrobial peptides (AMPs) are small cationic molecules that display antimicrobial activity against a wide range of bacteria, fungi and viruses. For an AMP to be considered as a therapeutic option, it must have not only potent antibacterial properties but also low hemolytic and cytotoxic activities [1]. Even though many studies have been conducted in order to correlate the antimicrobial activity with affinity toward model lipid membranes, the use of these membranes to explain cytotoxic effects (especially hemolysis) has been less explored. In this context, we studied lipid selectivity in two related novel AMPs, peptide 6 (P6) and peptide 6.2 (P6.2). Each peptide was designed from a previously reported AMP, and specific amino acid replacements were performed in an attempt to shift their hydrophobic moment or net charge. P6 showed no antimicrobial activity and high hemolytic activity, and P6.2 exhibited good antibacterial and low hemolytic activity. Using both peptides as a model we correlated the affinity toward membranes of different lipid composition and the antimicrobial and hemolytic activities. Our results from surface pressure and zeta potential assays showed that P6.2 exhibited a higher affinity and faster binding kinetic toward PG-containing membranes, while P6 showed this behavior for pure PC membranes. The final position and structure of P6.2 into the membrane showed an alpha-helix conversion, resulting in a parallel alignment with the Trps inserted into the membrane. On the other hand, the inability of P6 to adopt an amphipathic structure, plus its lower affinity toward PG-containing membranes seem to explain its poor antimicrobial activity. Regarding erythrocyte interactions, P6 showed the highest affinity toward erythrocyte membranes, resulting in an increased hemolytic activity. Overall, our data led us to conclude that affinity toward negatively charged lipids instead of zwitterionic ones seems to be a key factor that drives from hemolytic to antimicrobial activity.
Assuntos
Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Hemólise/efeitos dos fármacos , Lipídeos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Peptídeos Catiônicos Antimicrobianos/síntese química , Peptídeos Catiônicos Antimicrobianos/química , Relação Dose-Resposta a Droga , Membrana Eritrocítica/efeitos dos fármacos , Humanos , Lipídeos/química , Testes de Sensibilidade Microbiana , Relação Estrutura-AtividadeRESUMO
Con el objeto de determinar las causas y consecuencias psico-somáticas del aborto en las mujeres que ingresaron al Departamento de Ginecología y Obstetricia del Instituto Autónomo Hospital Universitario de Los Andes de Mérida, en el año 2003-2004, se planteo un trabajo de serie clínica retrospectiva, transversal, descriptivo y observacional, basada en la revisión de historias clínicas en los Archivos de Registro y Estadística. Seleccionando aquellas pertenecientes a mujeres que ingresaron con dicho diagnóstico entre enero 2003 a diciembre 2004, teniendo como variables: Edad Materna, Procedencia, Ocupación, Grado de Instrucción, Menarquia, Sexarquia, Contactos Sexuales, Gestaciones anteriores, abortos previos, Uso de métodos anticonceptivos, Edad gestacional por fecha de ultima regla o ecosonograma, Patología médica asociada, Diagnóstico clínico de ingreso, Complicaciones físicas, Complicaciones psicológicas. Se incluyeron 30 historias clínicas, en las cuales encontró que un gran porcentaje de los abortos se producen en la juventud (16) 60.4 por ciento; y el 47,1 por ciento procedía del Distrito Sanitario Mérida; se desempeñaban en los oficios del hogar el 47.1 por ciento y solo una tercera parte habrían alcanzado la secundaria completa, el 38.2 por ciento tuvo su menarquia a los 13 años y el 28.4 por ciento había iniciado su vida sexual a los 17 años; referían tener una pareja sexual el 48.2 por ciento y un poco mas de la mitad negaron el uso de métodos anticonceptivos 52 por ciento. Una tercera parte cursaban con su segundo embarazo y 95 mujeres (27) por ciento) ya habían abortado; la cuarta parte desconocía sus semanas de gestación, sin embargo el 55.9 por ciento de los abortos fueron precoces. Ninguna historia clínica registró signo-sintomatología psicológico o psiquiátrico, y en consecuencia tampoco hubo asistencia psicológica durante la hospitalización o posterior al egreso. En general, el comportamiento socio demográfico de las mujeres estudiadas.
Assuntos
Humanos , Feminino , Aborto , Aborto Induzido , Avaliação de Consequências de Desastres , Impacto PsicossocialRESUMO
The agenesis of the gall bladder is a rare congenital abnormality that usually is diagnosed as cholecystolithiasis. Therefore it is an intraoperative discovery. In this work two new cases are added to casuistry; both them have received laparotomic treatment. As those cases were symptomatic patients, the most common clinical manifestations are described. We insist in tactics to discard ectopic locations and the different options for the intraoperative and postoperative study; this last situation seems to be the most used behavior on patients approached laparoscopically.
Assuntos
Doenças Biliares/cirurgia , Vesícula Biliar/anormalidades , Adulto , Doenças Biliares/diagnóstico , Ducto Cístico/anormalidades , Feminino , Humanos , MasculinoRESUMO
The agenesis of the gall bladder is a rare congenital abnormality that usually is diagnosed as cholecystolithiasis. Therefore it is an intraoperative discovery. In this work two new cases are added to casuistry; both them have received laparotomic treatment. As those cases were symptomatic patients, the most common clinical manifestations are described. We insist in tactics to discard ectopic locations and the different options for the intraoperative and postoperative study; this last situation seems to be the most used behavior on patients approached laparoscopically.
RESUMO
The agenesis of the gall bladder is a rare congenital abnormality that usually is diagnosed as cholecystolithiasis. Therefore it is an intraoperative discovery. In this work two new cases are added to casuistry; both them have received laparotomic treatment. As those cases were symptomatic patients, the most common clinical manifestations are described. We insist in tactics to discard ectopic locations and the different options for the intraoperative and postoperative study; this last situation seems to be the most used behavior on patients approached laparoscopically. (AU)
Assuntos
Adulto , Humanos , Masculino , Feminino , Vesícula Biliar/anormalidades , Doenças Biliares/cirurgia , Doenças Biliares/diagnóstico , Ducto Cístico/anormalidadesRESUMO
The agenesis of the gall bladder is a rare congenital abnormality that usually is diagnosed as cholecystolithiasis. Therefore it is an intraoperative discovery. In this work two new cases are added to casuistry; both them have received laparotomic treatment. As those cases were symptomatic patients, the most common clinical manifestations are described. We insist in tactics to discard ectopic locations and the different options for the intraoperative and postoperative study; this last situation seems to be the most used behavior on patients approached laparoscopically.
Assuntos
Humanos , Masculino , Feminino , Adulto , Doenças Biliares/cirurgia , Vesícula Biliar/anormalidades , Doenças Biliares/diagnóstico , Ducto Cístico/anormalidadesRESUMO
The case of an intracranial tumor with intraventricular localization, in an usually healthy patient is presented. The main clinical symptom was the sudden onset of a strong intensity cephalea, which was persistent and unusual. The neurological examination did not show any abnormalities. Clinical aspects corresponding to this case are revised and compared with those reported in the literature.
Assuntos
Cistos do Sistema Nervoso Central/complicações , Cefaleia/etiologia , Terceiro Ventrículo , Adulto , Feminino , HumanosRESUMO
Este estudio compara la inmunogenicidad (seroconversión, seroprotección e hiperrespuesta), producida por dos vacunas recombinantes contra la hepatitis B (Engerix-B de Bélgica y Cubana), en dos esquemas (012 y 016 meses), empleando los métodos de cuantificación para anti-HBsAg (Abbott y Organón), los cuales fueron también comparados. En el estudio participaron 257 voluntarios, divididos al azar en 4 grupos (dos vacunas, dos esquemas). Resultados: los dos métodos de Abbott y Organon, no presentan diferencias estadísticas significativas. La vacuna cubana muestra una mayor respuesta inmunogénica para dos dosis de vacuna y para el esquema 012. No hay diferencia entre los esquemas 012 y 016 y en el esquema 016 no se ven diferencias estadísticamente significativas con la vacuna Engerix-B. En esta última el esquema 016 muestra mejores resultados que el 012
Assuntos
Vacinas contra Hepatite B/imunologia , Vacinas Sintéticas/imunologiaRESUMO
Non-ulcer dyspepsia is a frequent clinical entity characterized by chronic upper gastrointestinal symptoms without organic lesions by radiology, sonography or endoscopy. We studied simultaneously the rate of gastric emptying and gallbladder contraction in 10 patients with non-ulcer dyspepsia and in 10 healthy controls after ingestion of 500 cc of isotonic saline, and 500 cc of a liquid mixed meal, hypercaloric and hyperosmotic. The measurements were done by direct real-time ultrasonic imaging in fasting and were repeated at regular intervals (15-30 minutes) after the liquid meal, until complete gastric emptying was established. We found with the liquid mixed meal, the patients with non-ulcer dyspepsia had a significant delay in gastric emptying and gallbladder hypokinesis with faulty contraction and slow refilling. Dynamic ultrasonographic studies are useful in patients with non-ulcer dyspepsia.
Assuntos
Dispepsia/fisiopatologia , Vesícula Biliar/fisiopatologia , Esvaziamento Gástrico/fisiologia , Adulto , Dispepsia/diagnóstico por imagem , Feminino , Humanos , Soluções Isotônicas , Masculino , Pessoa de Meia-Idade , UltrassonografiaRESUMO
The most significant facts in the development of Chilean cardiology since 1930 are reviewed. The preeminence of great clinicians in the thirties was followed by the creation of Departments of Cardiology in University Hospitals. The emergence of powerful diagnostic tools and cardiac surgery allowed an accelerated develpment of this specialty in our country. Some of the problems faced by physicians and public in general as a consequence of the increasing use of sophisticated technology are discussed (AU)
Assuntos
História do Século XX , Cardiologia/história , História do Século XX , ChileRESUMO
The most significant facts in the development of Chilean cardiology since 1930 are reviewed. The preeminence of great clinicians in the thirties was followed by the creation of Departments of Cardiology in University Hospitals. The emergence of powerful diagnostic tools and cardiac surgery allowed an accelerated develpment of this specialty in our country. Some of the problems faced by physicians and public in general as a consequence of the increasing use of sophisticated technology are discussed