Aroma and flavor are important factors of fruit quality and consumer preference. The specific pattern of aroma is generated during ripening by the accumulation of volatiles compounds, which are ...mainly esters. Alcohol acyltransferase (AAT) (EC 2.3.1.84) catalyzes the esterification reaction of aliphatic and aromatic alcohols and acyl-CoA into esters in fruits and flowers. In Fragaria x ananassa, there are different volatiles compounds that are obtained from different alcohol precursors, where octanol and hexanol are the most abundant during fruit ripening. At present, there is not structural evidence about the mechanism used by the AAT to synthesize esters. Experimental data attribute the kinetic role of this enzyme to 2 amino acidic residues in a highly conserved motif (HXXXD) that is located in the middle of the protein. With the aim to understand the molecular and energetic aspects of volatiles compound production from F. x ananassa, we first studied the binding modes of a series of alcohols, and also different acyl-CoA substrates, in a molecular model of alcohol acyltransferase from Fragaria x ananassa (SAAT) using molecular docking. Afterwards, the dynamical behavior of both substrates, docked within the SAAT binding site, was studied using routine molecular dynamics (MD) simulations. In addition, in order to correlate the experimental and theoretical data obtained in our laboratories, binding free energy calculations were performed; which previous results suggested that octanol, followed by hexanol, presented the best affinity for SAAT. Finally, and concerning the SAAT molecular reaction mechanism, it is suggested from molecular dynamics simulations that the reaction mechanism may proceed through the formation of a ternary complex, in where the Histidine residue at the HXXXD motif deprotonates the alcohol substrates. Then, a nucleophilic attack occurs from alcohol charged oxygen atom to the carbon atom at carbonyl group of the acyl CoA. This mechanism is in agreement with previous results, obtained in our group, in alcohol acyltransferase from Vasconcellea pubescens (VpAAT1).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Salmonella Typhimurium is the etiological agent of gastroenteritis in humans and enteric fever in mice. Inside these hosts, Salmonella must overcome hostile conditions to develop a successful ...infection, a process in which the levels of porins may be critical. Herein, the role of the Salmonella Typhimurium porin OmpD in the infection process was assessed for adherence, invasion and proliferation in RAW264.7 mouse macrophages and in BALB/c mice. In cultured macrophages, a ΔompD strain exhibited increased invasion and proliferation phenotypes as compared to its parental strain. In contrast, overexpression of ompD caused a reduction in bacterial proliferation but did not affect adherence or invasion. In the murine model, the ΔompD strain showed increased ability to survive and replicate in target organs of infection. The ompD transcript levels showed a down-regulation when Salmonella resided within cultured macrophages and when it colonized target organs in infected mice. Additionally, cultured macrophages infected with the ΔompD strain produced lower levels of reactive oxygen species, suggesting that down-regulation of ompD could favor replication of Salmonella inside macrophages and the subsequent systemic dissemination, by limiting the reactive oxygen species response of the host.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective
To determine the best timing for thoracoscopic drainage of clotted hemothorax in order to ensure safe and effective results and to identify risk factors associated with drainage failure.
...Materials and methods
Cohort retrospective study of 139 consecutive patients who underwent thoracoscopic retained hemothorax drainage between April 1997 and May 2005.
Results
The procedure was successful in 102 patients (73.4%), in whom complete evacuation was achieved, with no accumulation of fluid in the pleural cavity requiring reintervention. Conversion to thoracotomy was required in 22 patients (15.8%) because of the inability to attain adequate drainage of clots and collections and lung re-expansion. Fifteen patients (10.8%) required reintervention as a result of fluid accumulation in the pleural cavity and lung collapse, and thoracotomy was performed in all those cases. The best results were obtained when thoracoscopic drainage was performed before the fifth day. There were 33 major post-operative complications including 20 cases of empyema of which 10 required thoracotomy, and 13 bronchopleural leaks, four of which required open surgery. There were no fatal outcomes in the study group.
Conclusions
Videothoracoscopy must be considered the procedure of choice for the treatment of retained post-traumatic hemothorax. It is a safe and effective procedure allowing the successful treatment of up to 73.4% of patients. Best results are obtained when drainage is performed within the first five days after trauma.
Background The National Nosocomial Infections Surveillance (NNIS) and Efficacy of Nosocomial Infection Control (SENIC) indexes are designed to develop control strategies and to reduce morbidity and ...mortality rates resulting from infections in surgical patients. We sought to assess the application of these indexes in patients under-going surgery for abdominal trauma and to develop an alternative model to predict surgical site infections (SSIs). Methods We conducted a prospective cohort study between November 2000 and March 2002. The main outcome measure was SSIs. We evaluated the variables included in the NNIS and SENIC indexes and some preoperative, intraoperative and postoperative variables that could be risk factors related to the development of SSIs. We performed multivariate analyses using a forward logistic regression method. Finally, we assessed infection risk prediction, comparing the estimated probabilities with actual occurrence using the areas under the receiver operating characteristic (ROC) curves. Results Overall, 614 patients underwent an exploratory laparotomy. Of these, 85 (13.8%) experienced deep incisional and organ/intra-abdominal SSIs. The independent variables associated with this complication were an Abdominal Trauma Index score greater than 24, abdominal contamination and admission to the intensive care unit. We proposed a model for predicting deep incisional and organ/intra-abdominal SSIs using these variables (alternative model). The areas under the ROC curves were compared using the estimated probabilities for this alternative model and for the NNIS and SENIC scores. The analysis revealed a greater area under the ROC curve for the alternative model. The NNIS and SENIC scores did not perform as well as the alternative model in patients with abdominal trauma. Conclusion The NNIS and SENIC indexes were inferior to the proposed alternative model for predicting SSIs in patients undergoing surgery for abdominal trauma.
Resumen Objetivo. Determinar la utilidad de la tomografía computadorizada (TC) en la selección para manejo no operatorio de pacientes con heridas abdominales por arma de fuego. Materiales y métodos. ...Se llevó a cabo un estudio observacional con la información de 62 pacientes mayores de 15 años con heridas por arma de fuego sin indicación de cirugía emergente, a quienes se les practicó TC de abdomen con triple contraste. Resultados. Se analizaron 276 pacientes con heridas por arma de fuego; a su ingreso, 214 se sometieron a cirugía urgente y a 62 se les practicó TC. De estos 62, en 14 estuvo indicada la cirugía por la TC, de los cuales, 12 tuvieron lesiones que requerían manejo quirúrgico y en dos la laparotomía no fue terapéutica. En los restantes 48 pacientes, la TC indicó manejo no operatorio. No obstante, en 2 de estos, se practicaron laparotomías tempranas, las cuales fueron terapéuticas. Los otros 46 pacientes recibieron manejo no operatorio: 43 fueron dados de alta sin complicaciones y 3 fueron sometidos posteriormente a laparotomía que resultó no terapéutica. Se presentó una tasa global de intervenciones no terapéuticas de 10,1 % y manejo no operatorio exitoso en 69,3 %. La sensibilidad de de la TC fue de 85,7 % (IC95% 63,8-100 %), la especificidad de 95,8 % (IC95% 89,1% -100%), el valor predictivo positivo de 85,7% (IC95% 63,8%-100%), valor predictivo negativo de 95,8% (IC95% 89,1%-100%); la razón de verisimilitud de un resultado positivo (Likelihood Ratio, LR+) fue de 21,5 y el de un resultado negativo (LR-) fue de 0,15. Conclusión. La TC es segura y confiable para predecir si los pacientes con heridas abdominales por arma de fuego son candidatos a manejo no operatorio.
The study aimed to establish the benefits of using chest tubes with negative pleural suction against trapped water in patients with penetrating or blunt chest trauma who underwent tube thoracostomy, ...in terms of the incidence of complications, such as persistent air leak, clotted hemothorax, empyema, and duration of stay.
Patients who underwent tube thoracostomy because of traumatic pneumothorax, hemothorax, or hemopneumothorax were randomly assigned into one of two groups: in Group 1, the three-bottle drainage system was connected to a negative suction; in Group 2, no suction was given. Patients who required mechanical ventilation or emergency surgery (thoracotomy or thoracoscopy) either at the time of admission to the institution or immediately after the tube thoracostomy, patients who had histories of thoracic procedures or chronic pulmonary diseases (chronic obstructive pulmonary disease, diffuse interstitial lung disease), and patients with multiple injuries with severe traumatic brain injury and a Glasgow Coma Scale (GCS) score less than 8 of 15 were excluded from the study. Hospital stay, duration of tube thoracostomy, prolonged fistula, and other clinical variables were compared.
One hundred ten patients were included, 56 in the group with suction and 54 in the group without suction. There were no differences in the demographic characteristics of each group. There were no differences between the groups in terms of hospital stay (p = 0.22), duration of tube thoracostomy (p = 0.35) (3 days in each group), or complications. However, the probability of air leak presence in time was greater for the Group 1 patients with negative suction versus the Group 2 patients (p = 0.023).
The use of negative pleural suction did not demonstrate advantages over the three-bottle chest drainage system without suction in patients with uncomplicated traumatic pneumothorax, hemothorax, or hemopneumothorax.
Therapeutic study, level II.
Introducción. La cirugía abierta ha sido el abordaje quirúrgico estándar para los tumores del estroma gástrico (Gastrointestinal Stromal Tumors, GIST). En artículos recientes se propone la cirugía ...laparoscópica como una alternativa segura para su tratamiento. Se hizo una evaluación de las publicaciones disponibles en las que se comparaban la seguridad y la efectividad de la cirugía laparoscópica con las de la cirugía abierta, en aspectos como tiempo quirúrgico, estancia hospitalaria, complicaciones y recurrencia tumoral. Materiales y métodos. Se hizo una búsqueda sistemática de la literatura y se evaluaron los artículos de más altacalidad según los criterios del Journal of the American Medical Association, JAMA. Se siguió la metodología del Best Evidence Topic (BestBET). Resultados Se encontraron tres revisiones sistemáticas de estudios observacionales. No hay a la fecha ensayos clínicos aleatorios. Los pacientes sometidos a laparoscopia presentan menor tiempo de reinicio de la vía oral y de estancia hospitalaria, y menor número de complicaciones globales y complicaciones menores. En comparación con la cirugía abierta, no hay diferencia con respecto a la pérdida sanguínea y el tiempo quirúrgico. Tampoco hay diferencia en tiempo de recurrencia y supervivencia libre de enfermedad. Conclusión. La evidencia a partir de estudios no aleatorios sugiere que la resección laparoscópica de los GIST gástricos es tan segura y efectiva como la vía abierta. La aplicabilidad de las técnicas quirúrgicas laparoscópicas se basa en una serie de factores que comprenden características del paciente, tamaño del tumor, localización, invasión y la experiencia del grupo quirúrgico en el abordaje laparoscópico.
PDF
