RESUMO

The Atacama Desert is the most arid desert on Earth, focus of important research activities related to microbial biodiversity studies. In this context, metabolic characterization of arid soil bacteria is crucial to understand their survival strategies under extreme environmental stress. We investigated whether strain-specific features of two Microbacterium species were involved in the metabolic ability to tolerate/adapt to local variations within an extreme desert environment. Using an integrative systems biology approach we have carried out construction and comparison of genome-scale metabolic models (GEMs) of two Microbacterium sp., CGR1 and CGR2, previously isolated from physicochemically contrasting soil sites in the Atacama Desert. Despite CGR1 and CGR2 belong to different phylogenetic clades, metabolic pathways and attributes are highly conserved in both strains. However, comparison of the GEMs showed significant differences in the connectivity of specific metabolites related to pH tolerance and CO2 production. The latter is most likely required to handle acidic stress through decarboxylation reactions. We observed greater GEM connectivity within Microbacterium sp. CGR1 compared to CGR2, which is correlated with the capacity of CGR1 to tolerate a wider pH tolerance range. Both metabolic models predict the synthesis of pigment metabolites (ß-carotene), observation validated by HPLC experiments. Our study provides a valuable resource to further investigate global metabolic adaptations of bacterial species to grow in soils with different abiotic factors within an extreme environment.

Assuntos

RESUMO

Robust fermentation performance of microbial cell factories is critical for successful scaling of a biotechnological process. From shake flask cultivations to industrial-scale bioreactors, consistent strain behavior is fundamental to achieve the production targets. To assert the importance of this feature, we evaluated the impact of the yeast strain design and construction method on process scalability -from shake flasks to bench-scale fed-batch fermentations- using two recombinant Saccharomyces cerevisiae strains capable of producing ß-carotene; SM14 and ßcar1.2 strains. SM14 strain, obtained previously from adaptive evolution experiments, was capable to accumulate up to 21 mg/gDCW of ß-carotene in 72 h shake flask cultures; while the ßcar1.2, constructed by overexpression of carotenogenic genes, only accumulated 5.8 mg/gDCW of carotene. Surprisingly, fed-batch cultivation of these strains in 1L bioreactors resulted in opposite performances. ßcar1.2 strain reached much higher biomass and ß-carotene productivities (1.57 g/L/h and 10.9 mg/L/h, respectively) than SM14 strain (0.48 g/L/h and 3.1 mg/L/h, respectively). Final ß-carotene titers were 210 and 750 mg/L after 80 h cultivation for SM14 and ßcar1.2 strains, respectively. Our results indicate that these substantial differences in fermentation parameters are mainly a consequence of the exacerbated Crabtree effect of the SM14 strain. We also found that the strategy used to integrate the carotenogenic genes into the chromosomes affected the genetic stability of strains, although the impact was significantly minor. Overall, our results indicate that shake flasks fermentation parameters are poor predictors of the fermentation performance under industrial-like conditions, and that appropriate construction designs and performance tests must be conducted to properly assess the scalability of the strain and the bioprocess.

RESUMO

INTRODUCTION: Capsule endoscopy (CE) is a non-invasive technique that allows visualization of small intestine mucosa. It is used for diagnosis of lesions not accessible with other tests. Our goal was to describe the experience using CE in a pediatric public hospital in Chile. PATIENTS AND METHOD: A retrospective study was carried out to review the cases in which CE was used at Dr. Luis Calvo Mac- kenna Hospital from 2010 to date. Demographic and clinical data, findings, complications, diagnosis and treatment were recorded. RESULTS: Twenty procedures were performed in 16 patients, 11 men (69%), median age 12 years (range 3 to 15 years). Indications included polyposis study (60%), sus pected Crohn disease (20%), obscure gastrointestinal bleeding (15%) and undiagnosed anemia (5%). Seventeen studies were altered (85%) and 11 led to a diagnosis or clinical behavior change (55%). There were no complications. CONCLUSIONS: CE is a useful and safe technique in children, feasible to perform in a pediatric public hospital.

Assuntos

RESUMO

INTRODUCCIÓN: La cápsula endoscópica (CE) es a una técnica no invasiva que permite la visualización de la mucosa del intestino delgado. Se utiliza para el diagnóstico de lesiones no accesibles con otros exámenes. El objetivo fue describir la experiencia de uso de CE en un hospital público pediátrico en Chile. PACIENTES Y MÉTODO: Estudio retrospectivo en que se revisaron los casos en que se utilizó CE en el Hospital Dr. Luis Calvo Mackenna desde 2010 hasta la fecha. Se registraron datos demográficos, clínicos, hallazgos, complicaciones, diagnóstico y conducta. RESULTADOS: Se realizaron 20 procedimientos en 16 pacientes, 11 varones (69%), mediana de edad 12 años (rango 3 a 15 años). Las indicaciones incluyeron estudio de poliposis (60%), sospecha de enfermedad de Crohn (20%), hemorragia digestiva de origen desconocido (15%) y anemia de causa desconocida (5%). Diecisiete estudios estaban alterados (85%) y 11 llevaron a un diagnóstico o cambio de conducta clínica (55%). Los hallazgos principales fueron pólipos y erosiones intestinales. No se produjeron complicaciones. CONCLUSIONES: La CE es una técnica útil y segura en niños, factible de realizar en un hospital público pediátrico.

INTRODUCTION: Capsule endoscopy (CE) is a non-invasive technique that allows visualization of small intestine mucosa. It is used for diagnosis of lesions not accessible with other tests. Our goal was to describe the experience using CE in a pediatric public hospital in Chile. PATIENTS AND METHOD: A retrospective study was carried out to review the cases in which CE was used at Dr. Luis Calvo Mac kenna Hospital from 2010 to date. Demographic and clinical data, findings, complications, diagnosis and treatment were recorded. RESULTS: Twenty procedures were performed in 16 patients, 11 men (69%), median age 12 years (range 3 to 15 years). Indications included polyposis study (60%), suspected Crohn disease (20%), obscure gastrointestinal bleeding (15%) and undiagnosed anemia (5%). Seventeen studies were altered (85%) and 11 led to a diagnosis or clinical behavior change (55%). There were no complications. CONCLUSIONS: CE is a useful and safe technique in children, feasible to perform in a pediatric public hospital.

Assuntos

RESUMO

BACKGROUND: Pichia pastoris shows physiological advantages in producing recombinant proteins, compared to other commonly used cell factories. This yeast is mostly grown in dynamic cultivation systems, where the cell's environment is continuously changing and many variables influence process productivity. In this context, a model capable of explaining and predicting cell behavior for the rational design of bioprocesses is highly desirable. Currently, there are five genome-scale metabolic reconstructions of P. pastoris which have been used to predict extracellular cell behavior in stationary conditions. RESULTS: In this work, we assembled a dynamic genome-scale metabolic model for glucose-limited, aerobic cultivations of Pichia pastoris. Starting from an initial model structure for batch and fed-batch cultures, we performed pre/post regression diagnostics to ensure that model parameters were identifiable, significant and sensitive. Once identified, the non-relevant ones were iteratively fixed until a priori robust modeling structures were found for each type of cultivation. Next, the robustness of these reduced structures was confirmed by calibrating the model with new datasets, where no sensitivity, identifiability or significance problems appeared in their parameters. Afterwards, the model was validated for the prediction of batch and fed-batch dynamics in the studied conditions. Lastly, the model was employed as a case study to analyze the metabolic flux distribution of a fed-batch culture and to unravel genetic and process engineering strategies to improve the production of recombinant Human Serum Albumin (HSA). Simulation of single knock-outs indicated that deviation of carbon towards cysteine and tryptophan formation improves HSA production. The deletion of methylene tetrahydrofolate dehydrogenase could increase the HSA volumetric productivity by 630%. Moreover, given specific bioprocess limitations and strain characteristics, the model suggests that implementation of a decreasing specific growth rate during the feed phase of a fed-batch culture results in a 25% increase of the volumetric productivity of the protein. CONCLUSION: In this work, we formulated a dynamic genome scale metabolic model of Pichia pastoris that yields realistic metabolic flux distributions throughout dynamic cultivations. The model can be calibrated with experimental data to rationally propose genetic and process engineering strategies to improve the performance of a P. pastoris strain of interest.

Assuntos

RESUMO

OBJECTIVE: Recurrent tracheoesophageal fistula (RTEF) is a serious complication after primary repair of esophageal atresia and tracheoesophageal fistula (EA/TEF). Treatment of RTEF involved an open surgery by thoracotomy. Technically it is a challenge with a high morbidity and mortality. Congenital tracheoesophageal fistula (CTEF) traditionally involved an open surgery by thoracotomy or cervicotomy. Many endoscopic techniques have been developed since the past decades: thoracoscopic or bronchoscopic approach for the treatment of RTEF and CTEF; nevertheless, optimal treatment is not still determined because of few numbers of patients, short-term follow-up, and different procedures. We report our experience and evaluated the efficacy in the chemocauterization of CTEF and RTEF, with the use of 50% trichloroacetic acid (TCA) as a technique minimally invasive. MATERIALS AND METHODS: From 2010 to 2014, fourteen patients with TEF (twelve RTEF and two CTEF) were selected for endoscopic management in two centers. Twelve patients had RTEF after primary repair of EA/TEF by thoracotomy approach, and two patients had CTEF in the upper pouch, diagnosed after EA/TEF (Type B) long gap, treated by thoracotomy and thoracoscopy, respectively. In all cases the diagnosis was confirmed by esophagram, bronchoscopy, and clinical evaluation. Under general anesthesia, a rigid pediatric bronchoscope with a 0° rod lens telescope and tele-monitoring was used to localize the TEF. Cotton soaked with 50% TCA was applied on the TEF during 30 s, and the procedure was repeated 3 times. The endoscopic treatment was performed monthly until TEF closure was achieved. RESULTS: RTEF and CTEF were closed in all patients. The mean number of procedure in each patient was 1.8. Closure of TEF was confirmed by esophagram, bronchoscopy, and clinical evaluation. There were a bacterial pneumonia and bronchospasm as postoperative complications. Median follow-up was 41 months (8-72). All of these TEF remain completely obliterated, and all patients are asymptomatic. CONCLUSION: Endoscopic management of congenital and recurrent TEF with the use of 50% TCA is as a minimally invasive, effective, simple and safe technique in these patients and avoids the morbidity of open surgery.

Assuntos

RESUMO

PURPOSE/BACKGROUND: The ingestion or accidental insertion of foreign bodies is extremely rare before 6 months of age. We report the case of a 3-month-old infant with a sewing needle into the right hepatic lobe, without symptoms. The extraction was performed through laparotomy. The issue is revisited, and the decision making tree is discussed.

Assuntos

RESUMO

UNLABELLED: Gastroesophageal reflux (GER) is a common disease in children less one year old. It is present around 10% of unselected infant population. 40-50% have abnormal 24 h pH monitoring. An early diagnosis and treatment should be done in order to avoid complications. AIM: To establish the consensus for the diagnosis and treatment of children with GER, to rule out similar diseases avoid the use of unnecessary drugs and the secondary side effects as well as unnecessary surgery. METHOD: The consensus was done with the participation of general pediatricians, pediatrics gastroenterologist, pediatric surgeons, radiologist and endoscopist. An initial paper was done by pediatric surgeon and pediatric gastroenterologist who submitted to the rest of participants. Second stage: the paper was review through E-mail for all participants who send their suggestions and modifications. A new paper was done and discussed by medical and surgery area. During the Congress of Pediatric Surgery, in an open session was discuss again with the participation of the main authors and all the audience present. Finally, a paper was done and review for the main authors.

Assuntos