RESUMEN
BACKGROUND: Multidrug resistant microorganisms are a growing challenge and new substances that can be useful to treat infections due to these microorganisms are needed. Silver nanoparticle may be a future option for treatment of these infections, however, the methods described in vitro to evaluate the inhibitory effect are controversial. RESULTS: This study evaluated the in vitro activity of silver nanoparticles against 36 susceptible and 54 multidrug resistant Gram-positive and Gram-negative bacteria from clinical sources. The multidrug resistant bacteria were oxacilin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., carbapenem- and polymyxin B-resistant A. baumannii, carbapenem-resistant P. aeruginosa and carbapenem-resistant Enterobacteriaceae. We analyzed silver nanoparticles stabilized with citrate, chitosan and polyvinyl alcohol and commercial silver nanoparticle. Silver sulfadiazine and silver nitrate were used as control. Different methods were used: agar diffusion, minimum inhibitory concentration, minimum bactericidal concentration and time-kill. The activity of AgNPs using diffusion in solid media and the MIC methods showed similar effect against MDR and antimicrobial-susceptible isolates, with a higher effect against Gram-negative isolates. The better results were achieved with citrate and chitosan silver nanoparticle, both with MIC90 of 6.75 µg mL(-1), which can be due the lower stability of these particles and, consequently, release of Ag(+) ions as revealed by X-ray diffraction (XRD). The bactericidal effect was higher against antimicrobial-susceptible bacteria. CONCLUSION: It seems that agar diffusion method can be used as screening test, minimum inhibitory concentration/minimum bactericidal concentration and time kill showed to be useful methods. The activity of commercial silver nanoparticle and silver controls did not exceed the activity of the citrate and chitosan silver nanoparticles. The in vitro inhibitory effect was stronger against Gram-negative than Gram-positive, and similar against multidrug resistant and susceptible bacteria, with best result achieved using citrate and chitosan silver nanoparticles. The bactericidal effect of silver nanoparticle may, in the future, be translated into important therapeutic and clinical options, especially considering the shortage of new antimicrobials against the emerging antimicrobial resistant microorganisms, in particular against Gram-negative bacteria.
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Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Infecciones Bacterianas/tratamiento farmacológico , Nanopartículas del Metal/química , Pruebas de Sensibilidad Microbiana/métodos , Plata/farmacología , Antibacterianos/química , Bacterias/citología , Bacterias/crecimiento & desarrollo , Infecciones Bacterianas/microbiología , Farmacorresistencia Bacteriana Múltiple , Humanos , Plata/químicaRESUMEN
PURPOSE: To analyze in an experimental animal model the effect of 4 different levels of stents-graft oversizing on non-atherosclerotic aortas such as those found in young individuals who undergo stent-graft repair for traumatic aortic injuries. METHODS: The diameter of the porcine thoracic aorta is similar to the aorta of young adults (18-20 mm), so 25 pigs were randomized into 5 groups: 1 control (without stent-graft) and 4 oversizing groups (A: 10%-19%, B: 20%-29%, C: 30%-39%, and D: >40%). Two types of biomechanical tests were performed on all aortas 4 weeks after endoprosthesis deployment. RESULTS: The results of the detachment test, which analyzed the strength necessary to remove the stent-graft from the aorta, were similar in the 4 groups (A: 42 N, B: 41 N, C: 46 N, and D: 46 N). However, 2 aortas ruptured during the tests (groups C and D). The second test was performed in 3 aortic segments. Maximum shear strength, maximum stress, and maximum tension supported by the aortic wall had a negative and linear correlation with oversizing. There were significant differences in all 4 groups when compared with the control group. Strain, which reflects the elastic properties of the aortic wall, was very similar in all 4 groups, but a great difference was found when compared with the control group (p<0.0001). CONCLUSION: The study showed an important subacute change in the biomechanical properties of the aortic wall after implantation of an oversized endoprosthesis. This weakness of the aortic wall was confirmed by 2 ruptures during the detachment test. These results partially explain the interaction of stent-grafts with non-atherosclerotic thoracic aortas and may serve as a basis for further studies and the development of specific material to be used in vascular trauma and young patients.
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Aorta Torácica/cirugía , Implantación de Prótesis Vascular/instrumentación , Prótesis Vascular , Procedimientos Endovasculares/instrumentación , Stents , Animales , Aorta Torácica/diagnóstico por imagen , Aorta Torácica/patología , Aortografía , Fenómenos Biomecánicos , Implantación de Prótesis Vascular/efectos adversos , Elasticidad , Procedimientos Endovasculares/efectos adversos , Modelos Animales , Diseño de Prótesis , Estrés Mecánico , Porcinos , Factores de TiempoRESUMEN
Sepsis remains a challenge for intensive care physicians, as it keeps up with high mortality rate in spite of the high costs associated with its treatment. Several studies indicate that the infusion of Drotrecogin-alpha activated (DrotAA) reduce mortality in patients at high risk of death when administered early and secured the appropriate initial treatment of sepsis as recommended by Surviving Sepsis Campaign. Europe and United States of America differ regarding the criteria of high risk of death in sepsis, two or more organ dysfunctions and Acute Physiology and Chronic Health Evaluation 25 or more, respectively. In addition to varied definitions of high risk of death for inclusion of patients in sepsis studies, the possibility of bleeding related to drug use and intrinsic limitations related to study design led the Company to develop a new randomized, multinational, placebo-controlled, double-blind study to assess the effectiveness of drug in patients with septic shock in adults.
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Estudios Multicéntricos como Asunto , Proteína C/uso terapéutico , Ensayos Clínicos Controlados Aleatorios como Asunto , Choque Séptico/tratamiento farmacológico , APACHE , Adulto , Animales , Factores de Coagulación Sanguínea/metabolismo , Protocolos Clínicos , Método Doble Ciego , Europa (Continente) , Fibrinólisis , Promoción de la Salud , Humanos , Inflamación , Cooperación Internacional , Estudios Multicéntricos como Asunto/métodos , Estudios Multicéntricos como Asunto/estadística & datos numéricos , Insuficiencia Multiorgánica/tratamiento farmacológico , Insuficiencia Multiorgánica/etiología , Insuficiencia Multiorgánica/mortalidad , Proteína C/efectos adversos , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto/estadística & datos numéricos , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico , Proyectos de Investigación , Choque Séptico/mortalidad , Trombofilia/tratamiento farmacológico , Trombofilia/etiología , Trombofilia/fisiopatología , Estados UnidosRESUMEN
Sepsis is a syndrome related to severe infections. It is defined as the systemic host response to microorganisms in previously sterile tissues and is characterized by end-organ dysfunction away from the primary site of infection. The normal host response to infection is complex and aims to identify and control pathogen invasion, as well as to start immediate tissue repair. Both the cellular and humoral immune systems are activated, giving rise to both anti-inflammatory and proinflammatory responses. The chain of events that leads to sepsis is derived from the exacerbation of these mechanisms, promoting massive liberation of mediators and the progression of multiple organ dysfunction. Despite increasing knowledge about the pathophysiological pathways and processes involved in sepsis, morbidity and mortality remain unacceptably high. A large number of immunomodulatory agents have been studied in experimental and clinical settings in an attempt to find an efficacious anti-inflammatory drug that reduces mortality. Even though preclinical results had been promising, the vast majority of these trials actually showed little success in reducing the overwhelmingly high mortality rate of septic shock patients as compared with that of other critically ill intensive care unit patients. Clinical management usually begins with prompt recognition, determination of the probable infection site, early administration of antibiotics, and resuscitation protocols based on "early-goal" directed therapy. In this review, we address the research efforts that have been targeting risk factor identification, including genetics, pathophysiological mechanisms and strategies to recognize and treat these patients as early as possible.
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Insuficiencia Multiorgánica/etiología , Sepsis , Humanos , Sepsis/complicaciones , Sepsis/fisiopatología , Sepsis/terapiaRESUMEN
Although cardiovascular effects of cocaine have been well studied, little is known about its effects on splanchnic perfusion. We studied systemic and regional hemodynamic effects of acute cocaine intoxication in dogs under volatile anesthesia. Mechanically ventilated beagle dogs, randomized at 1.5% halothane (n = 7) or 2.25% sevoflurane (n = 7) anesthesia, received an intravenous bolus of cocaine (12 mg/kg over 5 min) followed by 0.22 mg/kg/min infusion over 30 min. They were observed for 60 min thereafter. Cardiac index (CI), heart rate (HR), mean arterial pressure (MAP), portal blood flow (PBF), gastric PCO(2) (gas tonometry), blood gases, and lactate and cocaine levels were assessed. Cocaine bolus promoted significant reductions in CI (~50%), HR (~20%), MAP (~20%), and PBF (~50%), accompanied by increase in systemic and splanchnic oxygen extractions and in gastric mucosal-arterial PCO(2) gradient. Those changes were maintained during cocaine infusion and returned to baseline values parallel to plasmatic cocaine clearance. Unlike other shock states, regional parameters, including gastric mucosal-arterial PCO(2) gradient, were restored before systemic variables. A possible local vasodilatory effect of volatile agents could play a role in this phenomenon. Cocaine infusion in anesthetized animals promoted marked systemic and regional hemodynamic derangement, which was rapidly reversible with decay of cocaine plasmatic concentration.
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Cocaína/farmacología , Circulación Esplácnica/efectos de los fármacos , Anestesia , Animales , Presión Sanguínea/efectos de los fármacos , Gasto Cardíaco/efectos de los fármacos , Cocaína/sangre , Perros , Halotano/farmacología , Frecuencia Cardíaca/efectos de los fármacos , MasculinoRESUMEN
CONTEXT: Spontaneous cholecystocutaneous abscess or fistula is an extremely uncommon complication secondary to cholecystitis. Over the past 50 years fewer than 20 cases of spontaneous cholecystocutaneous fistulas have been described in the medical literature. We here report a case of subcutaneous gallstone as a rare clinical presentation of the already uncommon cholecystocutaneous fistula. CASE REPORT: An 81-year-old man presented with a large subcutaneous abscess in the right subcostal area with surrounding cellulitis and crepitus. An abdominal computed tomography scan showed two subcutaneous gallstones and communication between the abscess and the gallbladder. Cholecystectomy was performed and the abdominal wall abscess was drained externally. This case report demonstrates that maintaining a high degree of suspicion of this rare entity is helpful in achieving correct preoperative diagnosis, and that computed tomography scan should be performed in all cases of unexplained abdominal wall suppuration or cellulitis.
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Fístula Biliar/etiología , Colecistitis/complicaciones , Fístula Cutánea/etiología , Cálculos Biliares/etiología , Absceso/etiología , Anciano de 80 o más Años , Colecistectomía , Enfermedad Crónica , Resultado Fatal , Humanos , MasculinoRESUMEN
BACKGROUND: The surface of the implant is one of the many factors often associated with the occurrence of capsular contracture, the etiopathogeny of which remains unclear. The purpose of this study was to analyze the behavior of capsular contracture by means of applanation tonometry and histology using a midsized animal model. METHODS: Silicone breast implants were implanted into 33 pigs and observed at 30, 60, 180, and 270 postoperative days. RESULTS: Capsular contracture in smooth implants showed significantly greater pressure values of tonometry, and the smooth implant capsule was significantly thicker than the textured implant capsule. Both pressure and thickness of the capsules increased at each period. The collagenous layer did not show any difference considering the periods of time in which the total thickness was analyzed; on the other hand, the increase in total capsular thickness occurred by thickening of the noncollagenous layer in both smooth and textured implants. Taking into consideration both kinds of implants, histomorphometric analysis showed that thin fibers were replaced by thick fibers in later postoperatives periods (180 and 270 days). CONCLUSIONS: The greater incidence of capsular contracture in smooth implants was correlated with the progressive increase in total capsule thickness, due to a higher concentration of collagenous fibers, when compared with textured implants (p = 0.011; mean difference, 6.61), and a higher concentration of thick fibers (p = 0.034; average, >5.51 percentage points per field of thick fibers than the textured implants in all periods). Pigs are good animal models for studying the healing process after breast augmentation with implants.
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Materiales Biocompatibles/efectos adversos , Implantación de Mama/efectos adversos , Implantes de Mama/efectos adversos , Fibrosis/patología , Geles de Silicona/efectos adversos , Animales , Materiales Biocompatibles/administración & dosificación , Modelos Animales de Enfermedad , Fibrosis/etiología , Fibrosis/fisiopatología , Masculino , Manometría , Geles de Silicona/administración & dosificación , PorcinosRESUMEN
In order to increase the number of practical and discussion classes offered to students in the traditional-curriculum scenario, while decreasing the lecture-based ones and to create an online community to share knowledge on surgery, we developed and assessed the first online course for undergraduate medical students on experimental surgery at the Federal University of Sao Paulo-UNIFESP, Brazil. The purposes of the present study are: describe and discuss the process and the lessons learned involved in developing an undergraduate web-based course and analyze the students' attitude towards this educational environment. A group of medical students was taught online during 5 weeks on the theory of experimental surgery through video quizzes, required readings, collaborative activities using discussion board and asynchronous communication. The students' knowledge gain, their web session variables and the results of the course evaluation were used to support our study. The students have significantly improved their knowledge on experimental surgery after the course. Among factors in the online course that could possibly have contributed to this gain, the interactive activities (video quizzes), key element in our online material, seemed to be promising for candidates. The evaluation results demonstrated high levels of course functionality, effectiveness of its online content and acceptance among medical students. This study indicated that a web-based course for undergraduate students may be successfully developed and implemented in medical settings and the students seem to be quite supportive. We encourage undergraduate medical learning strategies involving the Web.
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Educación de Pregrado en Medicina/tendencias , Cirugía General/economía , Internet , Adulto , Actitud , Curriculum , Educación de Pregrado en Medicina/normas , Humanos , Conocimiento , Desarrollo de ProgramaRESUMEN
INTRODUCTION: We conducted the present study to investigate whether early large-volume crystalloid infusion can restore gut mucosal blood flow and mesenteric oxygen metabolism in severe sepsis. METHODS: Anesthetized and mechanically ventilated male mongrel dogs were challenged with intravenous injection of live Escherichia coli (6 x 10(9) colony-forming units/ml per kg over 15 min). After 90 min they were randomly assigned to one of two groups - control (no fluids; n = 13) or lactated Ringer's solution (32 ml/kg per hour; n = 14) - and followed for 60 min. Cardiac index, mesenteric blood flow, mean arterial pressure, systemic and mesenteric oxygen-derived variables, blood lactate and gastric carbon dioxide tension (PCO2; by gas tonometry) were assessed throughout the study. RESULTS: E. coli infusion significantly decreased arterial pressure, cardiac index, mesenteric blood flow, and systemic and mesenteric oxygen delivery, and increased arterial and portal lactate, intramucosal PCO2, PCO2 gap (the difference between gastric mucosal and arterial PCO2), and systemic and mesenteric oxygen extraction ratio in both groups. The Ringer's solution group had significantly higher cardiac index and systemic oxygen delivery, and lower oxygen extraction ratio and PCO2 gap at 165 min as compared with control animals. However, infusion of lactated Ringer's solution was unable to restore the PCO2 gap. There were no significant differences between groups in mesenteric oxygen delivery, oxygen extraction ratio, or portal lactate at the end of study. CONCLUSION: Significant disturbances occur in the systemic and mesenteric beds during bacteremic severe sepsis. Although large-volume infusion of lactated Ringer's solution restored systemic hemodynamic parameters, it was unable to correct gut mucosal PCO2 gap.
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Bacteriemia/terapia , Fluidoterapia , Mucosa Gástrica/irrigación sanguínea , Soluciones Isotónicas/administración & dosificación , Resucitación/métodos , Sepsis/terapia , Circulación Esplácnica/efectos de los fármacos , Animales , Bacteriemia/sangre , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Gasto Cardíaco/efectos de los fármacos , Gasto Cardíaco/fisiología , Perros , Escherichia coli/fisiología , Masculino , Modelos Animales , Lactato de Ringer , Sepsis/sangre , Sepsis/microbiología , Circulación Esplácnica/fisiología , Resistencia VascularRESUMEN
Transesophageal Doppler (TED) monitoring has been considered a noninvasive and accurate alternative to pulmonary artery catheterization for volume replacement and cardiac output measurement in patients undergoing major surgery. This study tested the hypothesis that TED can accurately predict cardiac output during hemorrhage, shock, and resuscitation, by comparing it to total pulmonary artery blood flow (PABF) and to standard intermittent bolus cardiac output (ICO). In eight anesthetized dogs (18 +/- 1.0 kg), PABF was measured with an ultrasonic flowprobe while ICO and mixed venous O2 saturation (SvO2) were measured through a Swan-Ganz catheter. A TED probe (CardioQ, Deltex Medical Inc., Irving, TX, U.S.A.), designed for adult use (minimum 30 kg, 16 years), was placed in midesophageous to evaluate stroke volume. A graded hemorrhage (20 mL/min) was produced (H5-H35) to a mean arterial pressure (MAP) of 40 mm Hg and maintained by additional blood removal for 30 min (S1-S30). Total shed blood volume was retransfused (541 +/- 54.2 mL) over 30 min (T5-T30), after which a massive hemorrhage, 100 mL/min rate, was produced over 10 min (MH5-MH10). In general, TED overestimated PABF (r2 = 0.3472), but changes in TED paralleled PABF throughout the experimental protocol, particularly during massive hemorrhage (r2 = 0.9001). We concluded that TED accurately reflected the direction and magnitude of the changes of cardiac output over time during abrupt hemodynamic changes. Probes designed for lower weights and smaller aortas may improve its accuracy in medium size animal models under less dramatic alterations induced by hemorrhage, shock, and resuscitation.