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Inanimate models represent reproducible, low-cost and readily available tools for the teaching and training of laparoscopic skills., Background and Objective: The use of training models in laparoscopic surgery allows the surgical team to practice procedures in a safe environment. The aim of this study was to determine the capability of an inanimate laparoscopic appendectomy model to discriminate between different levels of surgical experience (construct validity). Methods: The performance of 3 groups with different levels of expertise in laparoscopic surgery—experts (Group A), intermediates (Group B), and novices (Group C)—was evaluated. The groups were instructed of the task to perform in the model using a video tutorial. Procedures were recorded in a digital format for later analysis using the Global Operative Assessment of Laparoscopic Skills (GOALS) score; procedure time was registered. The data were analyzed using the analysis of variance test. Results: Twelve subjects were evaluated, 4 in each group, using the GOALS score and time required to finish the task. Higher scores were observed in the expert group, followed by the intermediate and novice groups, with statistically significant difference. Regarding procedure time, a significant difference was also found between the groups, with the experts having the shorter time. The proposed model is able to discriminate among individuals with different levels of expertise, indicating that the abilities that the model evaluates are relevant in the surgeon's performance. Conclusions: Construct validity for the inanimate full-task laparoscopic appendectomy training model was demonstrated. Therefore, it is a useful tool in the development and evaluation of the resident in training.

Objective With the coming of the laparoscopy, multiple surgical techniques have been developed that have revolutionized the urological practice. Laparoscopic pyeloplasty has been one of the most developed techniques. However, there are very few training models that permit the surgeon to decrease the learning curve. An animal model of training for the laparoscopic pyeloplasty technique is described. Methods Eight procedures of laparoscopic pyeloplasty were performed using the animal model ( Gallus gallus ) in the laparoscopic practice laboratory of the Urology Service of the University Hospital of Caracas. The preparation times of the model and the operation times of each surgeon were compared. The statistical analysis was made calculating the mean operation time, standard deviation, frequencies and percentages. A significant value was considered as p Results The laparoscopic pyeloplasty procedure was performed successfully in all of the cases by two surgeons. The preparation time ranged from a maximum of 14 min to a minimum of 6 min, this being the same for both surgeons in the fourth case. The operation time ranged from a maximum of 65 min to a minimum of 43 min, observing significant differences when comparing the times individually for each surgeon. Only one case had filtration when comparing the patency of the specimen. Conclusions The animal model of training of laparoscopic pyeloplasty that is described is economical, reproducible, of easy availability and it makes it possible to develop laparoscopic surgical skills and competency necessary for reconstructive surgery and techniques that warrant intracorporeal suture.

The objective of this study is to determine the ability of the GEARS scale (Global Evaluative Assessment of Robotic Skills) to differentiate individuals with different levels of experience in robotic surgery, as a fundamental validation. This is a cross-sectional study that included three groups of individuals with different levels of experience in robotic surgery (expert, intermediate, novice) their performance were assessed by GEARS applied by two reviewers. The difference between groups was determined by Mann-Whitney test and the consistency between the reviewers was studied by Kendall W coefficient. The agreement between the reviewers of the scale GEARS was 0.96. The score was 29.8 ± 0.4 to experts, 24 ± 2.8 to intermediates and 16 ± 3 to novices, with a statistically significant difference between all of them (p

Resumen Introduccion El tratamiento de la enfermedad varicosa producto del reflujo de la union safenofemoral ha variado en los ultimos anos con el advenimiento de novedosas tecnicas menos traumaticas. En el presente estudio se describe una tecnica y se describen sus ventajas en relacion con otros procedimientos actuales. Pacientes y metodos RSe trata de un estudio prospectivo, comparativo, de una muestra seleccionada de 36 casos. Se realizo una crosectomia y una escleroterapia con espuma de etoxiesclerol en 18 casos y una safenectomia convencional en los restantes. Resultados Para la tecnica descrita, el tiempo quirurgico promedio fue de 30 minutos. El tiempo promedio de hospitalizacion fue de un dia, con un reintegro a las actividades cotidianas en la segunda semana en todos los casos y una elevada tasa de satisfaccion (94,4%). En el seguimiento durante un periodo de 3 a 12 meses no se encontraron recurrencias. Se describio un caso de hiperpigmentacion como unica complicacion postoperatoria asociada con el procedimiento. Se demostro un beneficio con respecto a la safenectomia convencional en cuanto a tasa de complicaciones menores postoperatorias (5,5 frente a 33,3%, p Conclusion La escleroterapia con espuma en el tratamiento de la insuficiencia venosa superficial es una tecnica que ha demostrado su eficacia. La tecnica propuesta, es decir, la crosectomia y la esclerosis con espuma es una tecnica factible, con una tasa de exito comparable a la safenectomia, que ofrece las ventajas del tratamiento minimamente invasivo sin la necesidad de requerir en el area quirurgica equipos de alto coste, lo cual la hace mas accesible para centros no especializados.

Gain-of-function alterations in several components and modulators of the Ras-MAPK pathway lead to dysregulation of the pathway and cause a broad spectrum of autosomal dominant developmental disorders, collectively known as RASopathies. These findings demonstrate the importance of tight multilevel Ras regulation to safeguard signaling output and prevent aberrant activity. We have recently identified ezrin as a novel regulatory element required for Ras activation. Homozygosity mapping and exome sequencing have now revealed the first presumably disease-causing variant in the coding gene EZR in two siblings with a profound intellectual disability. Localization and membrane targeting of the altered ezrin protein appeared normal but molecular modeling suggested protein interaction surfaces to be disturbed. Functional analysis revealed that the altered ezrin protein is no longer able to bind Ras and facilitate its activation. Furthermore, expression of the altered ezrin protein in different cell lines resulted in abnormal cellular processes, including reduced proliferation and neuritogenesis, thus revealing a possible mechanism for its phenotype in humans. To our knowledge, this is the first report of an autosomal recessively inherited loss-of-function mutation causing reduced Ras activity and thus extends and complements the pathogenicity spectrum of known Ras-MAPK pathway disturbances.

In order to show the importance of plastic recycling, a study of the mechanical, thermal and thermodegradative properties of low-density polyethylene (LDPE) blends with virgin and recycled high-density polyethylene (HDPE) was made to assess the possibility of using recycled polymers, and consequently, reducing environmental pollution brought about by those materials. The formation of an additional phase was determined through thermal analysis of LDPE blends with virgin and recycled HDPE. In the study of mechanical behavior of these blends, this intermediate phase was observed to increase tensile strength and flexibility of samples, thus acting as an interfacial agent. Regarding activation energy obtained in thermogravimetric studies, it was concluded that a phenomenon occurs which delays decomposition process at 30% and 40% recycled HDPE. because at higher compositions, properties completely deteriorate. It is possible to use recycled HDPE in blends with LDPE. since raw materials cost is reduced ...

The recovery of plastic waste may be an incentive to industry, since the use of such plastics represents a cheaper source of raw material. The aim of the present paper is to study the feasibility of recycling polyolefins with copolymer additives to improve the mechanical properties and increase the useful life of the blends. The values obtained for the mechanical and thermal properties for polypropylene (PP) with recycled high density polyethylene (HDPE) show that it is possible to use recycled HDPE up to 30% w/w. The properties and applications are similar to those obtained with PP alone, thereby reducing the cost of the raw material. The addition of the compatibilizer at 5% represents the optimal concentration for improving the final properties of the finished product. Analysis of the mechanical and thermal behavior of the low density polyethylene (LDPE) with recycled HDPE blends lead us to conclude that it is possible to use recycled HDPE because the properties of the finished product are ther...

Ethylene polymerization has been studied in the presence of catalyst based on vanadium or vanadium-chromium supported on a zeolite HY. The effect of vanadium over chromium has been investigated as a function of the sequence of exchange of metals on the support and metal contents. Both effects were investigated in relation to the characteristics of the polyethylene (PE) obtained. Low activity has been found for the V (II) zeolite HY catalyst. Moreover, vanadium acts either as an inhibitor or as a promoter for the polymerizing activity of the Cr (III)/zeolite catalyst, depending on the preparation method. © 1994 John Wiley & Sons, Inc.

Macromolecular ligands have been widely used in the past two decades with the objective of preparing structurally defined heterogeneous catalysts from soluble organometallic complexes. This activity has been largely reconsidered and focused on few specific systems. In this connection the present paper reviews recent data concerning the preparation of macromolecular metal complexes derived from transition metals which can produce active catalytic complexes for olefin polymerization and oligomerization and comparison is made about the suitability of both organic resins (crosslinked polystyrene) and inorganic materials (silica, alumina and zeolites).

With the coming of the laparoscopy, multiple surgical techniques have been developed that have revolutionized the urological practice. The laparoscopic pyeloplasty has been one of the techniques most developed. However, there are very few training models that permit the surgeon to decrease the learning curve. An animal model of training for the laparoscopic pyeloplasty technique is described.Eight procedures of laparoscopic pyeloplasty were performed using the animal model (Gallus gallus) in the laparoscopic practice laboratory of the Urology Service of the University Hospital of Caracas. The preparation times of the model and the operation times of each surgeon were compared. The statistical analysis was made calculating the mean operation time, standard deviation, frequencies and percentages. A significant value was considered as p0.05.The laparoscopic pyeloplasty procedure was performed successfully in all of the cases by two surgeons. The preparation time ranged from a maximum of 14 minutes to a minimum of 6 minutes, this being the same for both surgeons in the fourth case. The operation time ranged from a maximum of 65 minutes to a minimum of 43 minutes, observing significant differences when comparing the times individually for each surgeon. Only one case had filtration when comparing the patency of the specimen.The animal model of training of laparoscopic pyeloplasty that is described is economical, reproducible, of easy availability and it makes it possible to develop laparoscopic surgical skills and competency necessary for reconstructive surgery and techniques that warrant intracorporeal suture.

Macromolecular ligands have been widely used in the past two decades with the objective of preparing structurally defined heterogeneous catalysts from soluble organometallic complexes. This activity has been largely reconsidered and focused on few specific systems. In this connection the present paper reviews recent data concerning the preparation of macromolecular metal complexes derived from transition metals which can produce active catalytic complexes for olefin polymerization and oligomerization and comparison is made about the suitability of both organic resins (crosslinked polystyrene) and inorganic materials (silica, alumina and zeolites).

Presentamos un caso de fístula colecistobiliar y colecistoduodenal (síndrome de Mirizzi tipo Va) resuelto por abordaje laparoscópico. El síndrome de Mirizzi representa una complicación de la litiasis vesicular que supone un reto quirúrgico, especialmente desafiante si se realiza por laparoscopia, ya que su resolución puede requerir destrezas especiales y equipos e instrumentos a los que el cirujano general no está habituado. Describimos el caso de una paciente femenina de 58 años de edad que consultó por presentar cuadro de ictericia obstructiva de dos semanas de evolución, con alteración del perfil hepático y ultrasonido abdominal que evidencia litiasis vesicular y dilatación del colédoco, se realiza colangiopancreatografía retrógrada endoscópica (CPRE), donde se evidencia imagen de defecto a nivel de la unión císticocoledociana, sin lograr la extracción del mismo. Se realizó el abordaje por vía laparoscópica, evidenciando síndrome adherencial severo, con presencia de fístula colecistoduodenal y colecistobiliar. Se procedió a la disección y sección del trayecto fistuloso entre la vesícula y la primera porción del duodeno, con cierre primario de este último. Posteriormente se realizó coledocotomía longitudinal y exploración de la vía biliar con el uso del coledocoscopio extrayéndose un cálculo de 1,5 cm, se realizó el cierre primario de la coledocotomía, y finalmente colecistectomía subtotal a nivel de la bolsa de Hartman con autosuturadora lineal-cortante de 45 mm. El abordaje laparoscópico del paciente con litiasis vesicular y síndrome de Mirizzi enfrenta al equipo quirúrgico a una situación difícil, sin embargo, es una alternativa factible siempre y cuando sea realizado por cirujanos con experiencia en cirugía laparoscópica avanzada de la vía biliar y se cuente con los recursos necesarios. Case report of the laparoscopic resolution of a type V Mirizzi´s Syndrome. This syndrome is a rare complication of the choletihiasis that becomes a surgical challenge, especially if made under laparoscopy, because it demands special skills and equipments uncommon to the general surgeons. A 58 years old female patient who presents a two weeks history of obstructive biliary syndrome. Hepatic enzymes were high and abdominal ultrasonography revealed gallstones and a dilated common bile duct. Endoscopic retrograde pancreatography (ERCP) revealed biliary stones in the junction between cystic duct and the common bile duct and the instrumentation was not effective. The laparoscopic approach showed severe adherences around the gallbladder with a cholecystoduodenal fistula and a cholecystobiliary fistula. We continue with the dissection and resection of the cholecystoduodenal fistula using primary closure of the duodenum. Afterwards we performed the transcholedochal common bile duct exploration and the capture of a 1,5 cm stone. Then we proceed with the primary closure of the common bile duct and subtotal cholecystectomy at the Hartman’s pouch using a 45 mm lineal autosuture. The laparoscopic management of patient with gallstones and Mirizzi´s syndrome is a difficult situation for the surgical team. However it is possible and save whenever a surgical team and the require resources are available.

Acquired urachal anomalies are a rare pathology. Gold-standard treatment for this clinical situation remains the resection of the urachus in its entire tract with or without partial resection of the bladder. Our aim is to up-date authors's experience in the minimally invasive surgical treatment of acquired urachal disease.From 2001 to 2007, 14 patients were operated for acquired urachal disease at our institution. A three portal technique previously described by the authors was employed. The diagnosis of acquired uracal disease was confirmed in all cases and the resection of the urachus in its entire tract performed in cephalocaudal direction onto the bladder. Operative and demographic data was prospectively collected and analysis retrospectively performed.Mean operative time was 63 minutes (45,110), minimal blood loss, and no conversions to open surgery or perioperative complications were verified. The majority of the patients were discharged in the first 24 hours. At a follow-up of 22 months no recurrences of urachal pathology recurrences have been verified.Laparoscopy plays a significant role in the management of symptomatic urachus anomalies. It allows objective confirmation of clinical diagnosis and adequate resection of the urachus in a safe and efficient fashion, while providing the well-known advantages of minimally acces surgery. Preoperative evaluation work-up has minimal impact of therapeutical decision.

Para comparar la efectividad del abordaje laparoscópico en pacientes con colecodolitiasis compleja versus el manejo laparoscópico en un solo tiempo se realizó un estudio prospectivo, que incluyó a 20 pacientes con indicación de exploración laparoscópica de la vía biliar en el período comprendido entre febrero 2005 y octubre 2008. Se estudiaron los pacientes con CPRE fallida y se compararon con pacientes manejados en un solo tiempo. En siete pacientes (35 %) la indicación de exploración de vías biliares fueron: alta sospecha de coledocolitiasis y CPRE fallida. La tasa de éxitos en este grupo fue de 57 % versus 84,7 % para los pacientes manejados en un solo tiempo. El tiempo quirúrgico promedio (187’ vs 106’) y la estadía hospitalaria (4,5 vs 2,3 días) estuvieron probablemente relacionados con la mayor complejidad de los casos. Los pacientes en los que se presentan dificultades en la resolución mediante CPRE, deben ser considerados casos complejos, en los cuales la efectividad del procedimiento laparoscópico disminuye y la tasa de conversión aumenta considerablemente. In order to compare the success of the laparoscopic exploration in patient with complicated choledocholitiasis versus single stage laparoscopic management, we realized a prospective study of 20 patients with indication of laparoscopic common bile duct exploration admitted in the period February 2005 - October 2008. We studied patients in whom the PCRE was ineffective versus single stage laparoscopic management. In seven patients (35 %) the indication of the laparoscopic common bile duct exploration was high risk of common bile duct stones and ineffective PCRE. The success rate was 57 % versus 84.7 % in the laparoscopic single stage management group. The surgical mean time (187’ vs 106’) and the hospital stay (4.5 vs 2.3 days) were probably related with the higher complexity of these cases. The patients with common bile duct stones in whom the PCRE is ineffective, must be considered complex cases. In these patients, the laparoscopic management success is lower with an increase conversion rate.

Presentamos un caso de mielolipoma suprarrenal gigante, para ilustrar la expresión y el manejo de esta rara patología. Este tumor benigno poco frecuente, compuesto de tejido hematopoyético maduro y tejido adiposo en proporciones variables, generalmente se diagnostica de forma incidental y sólo tiene indicación quirúrgica en aquellos casos en los que producen síntomas o alcanza grandes dimensiones. Describimos el caso de una paciente de 56 años, asintomática, con el hallazgo incidental de tumor suprarrenal de grandes dimensiones, tratado mediante resección quirúrgica en el servicio de Cirugía III del Hospital Universitario de Caracas. Case report of giant adrenal myelolipoma to describe the presentation and the treatment for this rare entity. This uncommon benign tumor, composed of variables proportions of mature hemopoyetic tissue and fat, is diagnosed incidentally and has indication of surgery only in the few cases in which it turns symptomatic or it reach big dimensions. We report the case of a 56-years-old asymptomatic female, in who is incidentally detected a giant adrenal tumor, surgically resected at the Hospital Universitario de Caracas, Servicio Cirugia III.

Introducción: Las anomalías uracales son una patología poco frecuente, el tratamiento aceptado consiste en la resección del uraco en todo su trayecto con o sin resección parcial de la vejiga. Nuestro objetivo es actualizar nuestra experiencia en el tratamiento de anomalías sintomáticas del uraco mediante cirugía de mínimo acceso. Pacientes y Métodos: Entre los años 2001 y 2007 se operaron 14 pacientes con anomalías adquiridas sintomáticas del uraco en nuestra institución. Se utilizó una técnica de tres portales previamente descrita por los autores, mediante la cual se realiza abordaje de la cavidad abdominal, confirmación del diagnóstico clínico inicial y resección del uraco en todo su trayecto en sentido cráneo caudal hasta la vejiga. Los datos demográficos y operatorios fueron recolectados de manera prospectiva y el análisis se realizó retrospectivamente. Resultados: El tiempo quirúrgico promedio fue de 63 minutos (45, 110) con sangrado mínimo, sin casos de conversión y sin complicaciones asociadas a la técnica. La gran mayoría de los pacientes egresó durante las primeras 24 horas. En un tiempo promedio de seguimiento de 22 meses no se han reportado recurrencias de la patología uracal. Conclusión: La laparoscopia juega un importante papel en el manejo de las anomalías sintomáticas del uraco, ya que permite confirmar el diagnóstico clínico y realizar la resección del uraco de manera segura y eficaz, aportando las ya conocidas ventajas de la cirugía de mínimo acceso. Los estudios de evaluación preoperatoria son de poca utilidad en la confirmación de esta patología.

Introducción: Las anomalías uracales son una patología poco frecuente, el tratamiento aceptado consiste en la resección del uraco en todo su trayecto con o sin resección parcial de la vejiga. Nuestro objetivo es actualizar nuestra experiencia en el tratamiento de anomalías sintomáticas del uraco mediante cirugía de mínimo acceso. Pacientes y Métodos: Entre los años 2001 y 2007 se operaron 14 pacientes con anomalías adquiridas sintomáticas del uraco en nuestra institución. Se utilizó una técnica de tres portales previamente descrita por los autores, mediante la cual se realiza abordaje de la cavidad abdominal, confirmación del diagnóstico clínico inicial y resección del uraco en todo su trayecto en sentido cráneo caudal hasta la vejiga. Los datos demográficos y operatorios fueron recolectados de manera prospectiva y el análisis se realizó retrospectivamente. Resultados: El tiempo quirúrgico promedio fue de 63 minutos (45, 110) con sangrado mínimo, sin casos de conversión y sin complicaciones asociadas a la técnica. La gran mayoría de los pacientes egresó durante las primeras 24 horas. En un tiempo promedio de seguimiento de 22 meses no se han reportado recurrencias de la patología uracal. Conclusión: La laparoscopia juega un importante papel en el manejo de las anomalías sintomáticas del uraco, ya que permite confirmar el diagnóstico clínico y realizar la resección del uraco de manera segura y eficaz, aportando las ya conocidas ventajas de la cirugía de mínimo acceso. Los estudios de evaluación preoperatoria son de poca utilidad en la confirmación de esta patología. Introduction: Acquired urachal anomalies are a rare pathology. Gold-standard treatment for this clinical situation remains the resection of the urachus in its entire tract with or without partial resection of the bladder. Our aim is to up-date authors´s experience in the minimally invasive surgical treatment of acquired urachal disease. Methods: From 2001 to 2007, 14 patients were operated for acquired urachal disease at our institution. A three portal technique previously described by the authors was employed. The diagnosis of acquired uracal disease was confirmed in all cases and the resection of the urachus in its entire tract performed in cephalocaudal direction onto the bladder. Operative and demographic data was prospectively collected and analysis retrospectively performed. Results: Mean operative time was 63 minutes (45,110), minimal blood loss, and no conversions to open surgery or perioperative complications were verified. The majority of the patients were discharged in the first 24 hours. At a follow-up of 22 months no recurrences of urachal pathology recurrences have been verified. Conclusions: Laparoscopy plays a significant role in the management of symptomatic urachus anomalies. It allows objective confirmation of clinical diagnosis and adequate resection of the urachus in a safe and efficient fashion, while providing the well-known advantages of minimally acces surgery. Preoperative evaluation work-up has minimal impact of therapeutical decision.

Small contracted bladder remains a challenge in clinical urological practice and treatment options are not always effective. Urothelium sparing surgical techniques represent a reasonable therapeutical option. We aimed to evaluate the feasibility of a rabbit model (Oryctolagus cuniculus) in the teaching and training setting for laparoscopic vesical autoaugmentation.Transperitoneal laparoscopic bladder autoaugmentation was performed in five New Zealand male rabbits (Oryctolagus cuniculus). A three port technique was used for all cases. Circumferential detrusorectomy was performed with vascular pedicles sparing, subsequently submucosal detailed blunt dissection allowed the creation of a bladder diverticulum which was verified intraoperatively. Eye-ball cystometry was performed preoperatively and postoperatively to verify bladder capacity variations. Postoperatively cystometry was done immediately after the procedure and 7 and 15 days postoperatively. Statistical analysis was performed with T-student model. A p-value0.05 was considered of significance for the analysis. Surgical procedure and perioperative animal care was minutely precised according to the Guidelines of the Institute of Laboratory Animal Resources, Commission on Life Sciences, National Research Council.Five New Zealand male rabbits (Oryctolagus cuniculus) were surgically treated as described. Median operative time was 68.8 minutes (range 44 -120). Median preoperatory bladder capacity for the series was 25.8 cc (7-52). Median postoperative bladder capacity was diminished in 33% immediately after the operation. Then, bladder capacity augmented 72% and 52% for 7th and 15th postoperative days, respectively. Percentage variation in bladder capacity is statistically significant. Two operative complications (mucosal tear) were reported. A postoperatory abscess was observed in one animal.The rabbit (Oryctolagus cuniculus) model for the laparoscopic bladder autoaugmentation is feasible for teaching, training and research. Bigger series and longer follow-up should be addressed.

La incidencia de los cálculos intrahepáticos en las sociedades occidentales es muy baja, sin embargo, la presencia de estos es todo un reto, ya que el manejo con colangiopancreatografía retrógrada endoscópica, es efectivo sólo en un pequeño porcentaje de los pacientes. Las opciones quirúrgicas son muy variables. El objetivo de este trabajo es describir un caso clínico de litiasis biliar intrahepática resuelto con el uso de colangioscopia intraoperatoria mediante coledocotomía y extracción de cálculos bajo visión directa con canastillas helicoidales, la cual es considerada como una de las mejores opciones quirúrgicas. The incidence of intrahepatic lithiasis in western societys is low, however, the diagnosis of this entity is really a challenge. The endoscopic management using retrograde cholangiopancreatography is effective in a low percentage of the patients. There are many surgical options, the purpose of this paper is to describe a case of intrahepathic lithiasis treated using intraoperative cholangioscopic through choledochotomy and stones removal under direct vision with helicoidal baskets, as one of the best surgical option in this cases.

Los quistes esplénicos verdaderos constituyen una rareza, es por ello que presentamos el caso de una paciente de 21 años de edad tratada por un quiste esplénico gigante (30 cm) con elevación del Ca 19-9 (1670U/mL) a quien se le realizó esplenectomía con evolución satisfactoria y sin complicaciones. La biopsia definitiva reportó quiste esplénico verdadero, siendo estas lesiones poco frecuentes, más aun cuando cursan con elevación del Ca 19-9, encontramos que se han publicado en la literatura consultada alrededor de 30 casos. The true cyst spleen are a poor known pathology, for these reason we report the case of a 21-year-old woman with a giant true spleen cyst (30 cm) with a high CA 19-9 serum level (1670 U/mL). The patient underwent splenectomy without complications and she has a successful postoperative course. The histopathological diagnosis was a true splenic cyst being these lesions very rare; approximately 30 cases of benign true splenic cysts with a high CA 19-9 serum level have been published in the literature.

Background: Urachal disease is uncommon. The surgical treatment consists of the resection of the urachus throughout its entire length. Our objective is to demonstrate the use of minimally invasive surgery to treat this disease. Methods: Six patients were studied and diagnosed. The technique used three 10-mm ports on the right hemi abdomen, through which the dissection of the urachus was performed from the umbilical extreme to the bladder. We evaluated the perioperative records to assess morbidity and outcome. Results: Most patients suffered from episodes of umbilical discharge. The diagnosis was made mainly through clinical history and confirmed during the laparoscopic procedure. The urachus was resected throughout its entire length, and we did not perform a segmentary bladder resection in any patient. The average operative time was 66 minutes (range, 42 to 123), and no operative complications were associated with the technique. Discussion: Minimally invasive surgery is a safe and effective procedure that allows the dissection of the urachus through its entire length, providing optimal postoperative results.

This paper investigates the homo- and copolymerization of styrene with p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene and 2,4,6-trimethylstyrene using a Cp*TiCl3 (Cp: cyclopentadienyl) semimetallocene catalyst activated with methylaluminoxane. Syndiotactic homo- and copolymers were obtained only for the monosubstituted monomers. For the di- or trisubstituted monomers, reduced reactivities, stereoregularities, and degrees of polymerization were obtained with respect to the monosubstituted monomers. More specifically, the homopolymerization of 2,5-dimethylstyrene and 2,4,6-trimethylstyrene and their copolymerization with styrene was inhibited. The reason for this are combined steric and inductive effects. The presence of methyl groups in para position seems to inhibit crystallization of the syndiotactic polymers. In contrast, crystallinity was evidenced in the materials produced in the presence of m-methyl substituted monomers.

The determination of the active site for the olefin disproportionation catalyst Mo Al 2 O 3 is the object of the present ESR, uv and kinetic investigation. Comparison of the rate of disproportionation with that of reduction Mo 6+ → Mo 5+ shows that Mo 6+ is the active site, the aging of the catalyst being the result of the reduction of Mo 6+ to Mo 5+ by the reactant. The variation of catalytic activity with Mo content shows a maximum at 7% Mo, which is also the case for the number of oxidizing sites Mo 6+ . The highest activity is obtained for a pretreatment temperature of 580 °C under O 2 , which is also in favor of Mo 6+ as the active species. Ultraviolet spectroscopy shows that two types of symmetry occur in the case of Mo Al 2 O 3 catalyst: tetrahedral and octahedral. However, by comparing the ESR and uv spectrum of Mo 5+ , it seems that only Mo 6+ in octahedral coordination is the active species. A model of the active Mo 6+ site with a symmetry C 4 v , is proposed. New considerations must be advanced for the mechanism of disproportionation taking into account the C 4 v , symmetry and the high oxidation state of the active site. Kinetic studies have also shown a high selectivity in favor of the cis isomer of butene at low temperature.