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The aim of this study was to describe the tracheal growth pattern and its zoometric relationship in related medium-sized mongrel puppies through adulthood. Fourteen puppies were studied. CT monitoring was performed monthly, starting in the 1st month of life through the 7th month and subsequently at the 9th and 12th months. Additionally, six zoometric measurements were performed. Dorsoventral (DV) and transverse (TV) diameters and the luminal area from C1 to T2 were obtained. The global tracheal growth pattern revealed an increase up to 13 times its initial size, reaching a plateau phase during the last trimester. The relationship between the DV and the TV internal diameters of the tracheal lumen did not change during growth. As previously reported, the cranial tracheal area was wider, while the caudal part gradually decreased towards T1-T2; this consideration is important since the more distal an endotracheal tube is inserted, the greater the risk that injury may occur. The linear correlation between the zoometric measurements and the tracheal ring areas was positive. This study provides evidence for the evaluation of the morphometry of the canine trachea during physiological growth using helicoidal CT as a non-invasive, accurate tool.

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OBJECTIVES: A longitudinal, randomized, single blind study was done to evaluate the efficacy of an antibacterial hybrid molecule (beta-lactamic-fluoroquinolone) named cephalone after biliary-enteric-bypass (BEB). MATERIAL AND METHODS: Four groups of mongrel dogs were operated on three consecutive periods. Cultures of bile and liver were obtained and assessed, followed by obliteration of common bile duct and BEB to groups A, B and C. Group D served as a control. Ten days later the group A received conventional treatment based on ampicillin/gentamicin and groups B and C, cephalone in two different concentration schemes during 10 consecutive days. Further samples were processed for bacteria and additional liver biopsies were obtained for histopathological analysis. RESULTS: All three treatments reverted bacterial contamination in the liver and most of the bile samples were negative or showed a significant decrease in the number of colony forming units (p = 0.002). Histopathological analysis proved no lesions. CONCLUSIONS: Comparison of efficacy among antibacterial treatments revealed undistinguishable efficacy in this short-term assessment of bacterial contamination after BEB in dogs. The use of cephalone could be considered as a viable treatment or prophylaxis in bacterial infections occurring after BEB. Further studies are needed to assess long-term impact of the cephalone in this setting.

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OBJECTIVE: Fibrocollagen-covered polyester meshes can be used as possible substitutions for tracheal segments if they become integrated into the tissue without complications. The aim of this study was to assess a fibrocollagen-covered polyester prosthesis to be used as a substitution for a tracheal segment. METHODS: We performed a blind, randomized experimental assay. Adult Wistar rats were assigned to one of 2 groups. Prostheses were made by implanting polyester tubing in a group of animals to cover them with homologous collagen. They were implanted as substitutions of tracheal segments in the experimental group after creating a defect in the anterior wall of the trachea. Clinical, histomorphologic, and immunohistochemical assessments were made at 4 different time points. RESULTS: The experimental group presented some respiratory distress signs during the first 7 to 10 days, such as stertors, hissing, and low motor activity. After this initial period, the symptoms subsided progressively and disappeared at the end of the first month. These respiratory symptoms caused no mortality. Initially undifferentiated monolayer cells predominated on the implant's surface, but during the last 2 months, the proportion of epithelial and ciliated cells was similar to that seen in control animals. Types I, III, and V collagen fibers were identified around the mesh. The intraluminal area of the tracheas with prostheses and prosthesis thickness were larger during the 4 months of the experiment. The increase in thickness was due to angiogenesis without evidence of fibrosis or chronic inflammation. CONCLUSIONS: Polyester-collagen prostheses used as substitutions of tracheal segments in rats enabled the proliferation of normal respiratory epithelium and maintained tracheal function without collapse, inflammatory reaction, or secondary stenosis.

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BACKGROUND: Medical professional proficiency comprises a set of skills, knowledge, and attitudes necessary to efficiently accomplish the practice of medicine. We undertook this study to identify the surgical/medical competencies (SMC) acquired by a group of students after graduating from the Faculty of Medicine, National Autonomous University of Mexico. METHODS: This was a cross-sectional, comparative, observational, and prospective study. Students from the class (1999-2003) who accepted to participate were included in the study. Thirty SMC were evaluated as well as demographic and academic background data from the graduates. Data were analyzed using Mann-Whitney, Kruskal-Wallis andX2tests. RESULTS: Of 341 interviewees, 310 subjects participated in the study; 61% of all participants were females. Mean age at graduation was 25 years; 66% of all participants concluded their medical training in 6 years; 30% of the interviewees had a < or = 8.0-point grade average score; 62% concluded their 6th school year in a Mexican Institute of Social Security (IMSS) and/or in a Ministry of Health (SSa) facility. Subjects reported having little or no command over 21/30 listed SMCs. Female participants rated themselves as less proficient than their male counterparts (p < or = 0.05). The presence of three other concomitant factors among several participants negatively influenced their self-perception of whether or not they possessed certain skills. CONCLUSIONS: A group of recently graduated physicians subjectively perceived themselves as possessing partial or no command over the SMCs included in the Surgery Department syllabus. These results must be completed through an objective assessment.

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Introducción: La principal complicación del uso de los expansores titulares (ET) son las infecciones. Una alternativa para evitarla, es agregar antibióticos que se difundan a través de la pared de un ET y eviten la colonización bacteriana. El objetivo de este trabajo fue evaluar la eficacia de una presentación nacional de cotrimoxazol, para difundirse a través de un ET en diferentes volúmenes de expansión. Material y método: Se realizó un experimento longitudinal con 12 ET, llenados a 50,100, 150 o 200% de su capacidad nominal, con solución fisiológica y cotrimoxazol a una concentración de 800/4000 ug/mL de trimetoprin/sulfametoxazol (TMX/SMX), sumergidos posteriormente en un sistema cerrado. Se midió la presión en el interior del ET, al inicio y al final del experimento. En los cuatro grupos se cuantificó la concentración de cotrimoxazol en la solución del contenedor, durante nueve días consecutivos. Los resultados se compararon mediante ANOVA de dos vías. Resultados: El SMX se precipitó dentro del ET. Las concentraciones de TMX en la solución del contenedor fueron diferentes en función del tiempo y el porcentaje de expansión. No hubo correlación entre el porcentaje de expansión y la presión dentro del ET. Conclusiones: La sinergia de cotrimoxazol de uso endovenoso disponible en nuestro país, no es una buena opción a emplearse en un ET a las dosis utilizadas, ya que el coeficiente de solubilidad de SMX se saturó y se formaron cristales. El incremento de difusión de TMX estuvo asociado con un mayor porcentaje de expansión, lo que es una ventaja, considerando que las infecciones son más frecuentes al final del proceso de expansión.

Introduction: Infection associated with tissue expansion is one of the main complications and force to take away the tissue expander. An alternative to avoid this action is to dilute antibiotics inside it. The aim of this experiment was to quantify the concentration of cotrimoxazole diffused through a tissue expander at different expansion and pressure volumes. Material and methods: A test was performed with 12 tissue expanders immersed in a closed system. These were divided in 4 sets according to the introduced expansion rate. Three independent variables were considered: percentage of lumen volume introduced into the expander, pressure inside the expander, and experiment duration. The concentration of the drug diffused through the expander was taken as dependent variable. The solution in which the expander was immersed was continuously sampled and drug concentration was determined by High Performance Liquid Chromatography (HPLC). ANOVA was used to determine differences between concentrations measured of every variable applied. Results: Only trimethoprim (TMX) diffused. No lineal correlation was observed between expansion rate and pressure inside the expander. The difference with respect to time and concentration of the drug outside the expander was statistically significant among the 4 sets of expanders (p = 0.0000). Conclusion: Sulfametoxazole (SMX) did not diffuse and crystallized inside the expander because of the different pk of the two drugs (SMX-TMX) respect to pH of dilution which was similar to pK of trimethoprim. The expansion rate had a proportional effect on TMX concentration outside the expander: an over-expansion of the system greater than 200% increases diffusion highly.

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INTRODUCTION: This study was undertaken to determine the characteristics of scientific articles published by Mexican pediatric surgeons (MPS) available in the major electronic databases for international and national medical information. MATERIAL AND METHODS: An observational, descriptive and transversal study was performed. Articles written by pediatric surgeons were localized in the most frequently accessed electronic searches: Medline, EMBASE, LILACS, and ARTEMISA, in the period from January 1991 to December 2002. Articles were grouped into three categories. RESULTS: A total of 247 publications were analyzed, 199 devoted to clinical research, 11 to basic research, and 37 reviews. Of the clinical research studies, 189 were observational-descriptive studies, and 151 of these were retrospective. Only 7.6% of the pediatric surgeons certified by the Mexican Council for Pediatric Surgery published an article (61 authors). Most studies (80%) was performed at Mexico City institutions. CONCLUSIONS: Most studies published by pediatric surgeons describe common problems of the Mexican pediatric population. A smaller percentage focus on comparing therapeutic actions or diagnostic strategies; however, result reliability is questionable due to experimental design. The contribution by MPS to the generation of medical publications during the last decade has been sparse, and more so from places other than Mexico City.

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BACKGROUND: Postsurgical complications in patients with esophageal atresia have remained unchanged during the last three decades. This study was aimed at investigating certain risk factors for small-sized esophageal anastomosis and to assess the probable relationship between esophageal length and body weight in rabbit. METHODS: Six groups of 10 adult rabbits were subjected to section or 1-cm segmental resection of thoracic esophagus followed by end-to-end anastomosis. Approximation strength of esophageal ends was measured. Three different suture materials were used, and three different surgeons carried out procedures. Observed morbidity was recorded, as well as leakage or stenosis frequency in suture line. Esophageal length and body weight of nonresected rabbits were measured. RESULTS: Fifteen leakages were observed in suture line; there were no differences in relative risk between groups with and without resection, or in ratio of this complication among surgeons; nonetheless, a greater number of leakages (p < 0.05) was observed at higher tension. There were no differences in magnitude of stenosis among surgeons, tension degree, or suture material used. Quadratic association was found between length of thoracic esophagus and body weight in nonresected rabbits. CONCLUSIONS: Rabbit esophagus is a suitable model to assess early surgical complications but not for late complications. Among three assessed factors, increased tension in patients with segmental deficit was the most significant factor in development of anastomotic leakage. Existence of nonlineal correlation between esophageal length and body weight in rabbit showed that resection of 1 cm of esophagus represented a different weight-dependent segmental deficit, which increased as weight decreased.

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Background. Short bowel syndrome (SBS) continues to be one of the most challenging problems in pediatric surgery. Intestinal transplantation (IT) seems to be best form of treatment for this pathology. However, it is thought that the development of an IT programs may be more expensive than the present manner of treatment. Methods. To assess this item, and to identify potential candidates for IT, we reviewed the charts of all the patients with SBS treated at our Institute from 1989 to 1994. Results. Nine patients were identified as carriers of SBS; six with intestinal atresia, two with midgut volvulus and one with post-traumatic mesenteric thrombosis. The small bowel remnants varied from 1 to 80 cm, seven patients had remnants shorter than 30 cm, and the ileocecal valve was resected in three. Results. The overall morbidity and mortality was extremely high; four patients died within the first 3 months postresection and those still alive have had several complications: sepsis; hydroelectrolyte imbalances secondary to loose stools; thrombosis or infection of the catheter; TPN-related cholestasis, and malabsorption syndromes, etc. No patient survived with an intestinal remnant shorter than 15 cm. Of the five survivors, four have a weight/age deficit greater than 40 percent, two have rickets, one still depends on TPN and all, except one, require special enteral diets. Multiple central venous accesses had to be performed in every patient (mean 4.8). They all required multiple readmissions and have spent a considerable part of their lives as inpatients. The mean of the calculated cost per patient was $50,000 USD, while the minimal wage in mexico is $1,616 USD/year (1). conclusions. The shorter the segment of the retained bowel and the longer the survival, the higher the cost. These results may be further improved with the development of IT and, probably, with the same economic burden

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La atresia de esófago es una malformación grave que requiere de una estrategia bien definida de manejo médico-quirúrgico; el diagnóstico temprano e integral representa el mejor medio para ubicar la ruta más apropiada de tratamiento y determinar el pronóstico del paciente. En México existe poca información escrita al respecto y la sobrevida difiere significativamente de lo descrito en países desarrollados. En esta revisión se señalan algunos de los aspectos mas sobresalientes de esta enfermedad y se presenta un esquema de toma de decisiones que permite agilizar el diagnóstico y tratamiento subsecuente

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Objetivo. Evaluar la respuesta funcional, morbilidad y posibles cambios histoestructurales en animales enterectomizados y sin ciego, sujetos a dos tipos de trasplante anteral singénico. Material y método. Ensayo terapéutico-quirúrgico, aleatorio, controlado. Cuatro grupos de ratas Lewis macho de 8-10 semanas de vida se sometieron a los siguientes tratamientos: 1. Resección enteral letal (n=10). 2. Resección enteral letal + trasplante yeyuno-ileal total (n=28). 3. Resección enteral letal + trasplante segmentario distal de 40 por ciento y ciego (n=32). 4. Grupo testigo (n=10). Resultados. El 11 por ciento de los animales trasplantados falleció por fallas quirúrgicas. Hubo una proporción similar de complicaciones tardías en ambos grupos trasplantados: la más común fue obstrucción enteral; 20 por ciento de los trasplantes yeyuno-ileales presentó diarrea persistente. En los dos grupos trasplantados no se detectaron diferencias significativas, de sobrevida, incremento de peso, niveles séricos de proteínas, triglicéridos y prueba de absorción de la maltosa. En ambos tipos de injertos se observó hipertrofia de vellosidades y criptas. El injerto enteral se acompaño de cambios estructurales semejantes a los que se presentan en los remanentes inestinales en condiciones de déficit enteral postresección. Conclusión. El trasplante segmentario distal de intestino, con válvula íleaca y ciega, puede ser una buena opción terapéutica en la insuficiencia enteral irreversible, dado que la respuesta funcional y la morbilidad asociada no difieren de las del trasplante total

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