Anisotropic expansion of hepatocyte lumina enforced by apical bulkheads.

Lumen morphogenesis results from the interplay between molecular pathways and mechanical forces. In several organs, epithelial cells share their apical surfaces to form a tubular lumen. In the liver, however, hepatocytes share the apical surface only between adjacent cells and form narrow lumina that grow anisotropically, generating a 3D network of bile canaliculi (BC). Here, by studying lumenogenesis in differentiating mouse hepatoblasts in vitro, we discovered that adjacent hepatocytes assemble a pattern of specific extensions of the apical membrane traversing the lumen and ensuring its anisotropic expansion. These previously unrecognized structures form a pattern, reminiscent of the bulkheads of boats, also present in the developing and adult liver. Silencing of Rab35 resulted in loss of apical bulkheads and lumen anisotropy, leading to cyst formation. Strikingly, we could reengineer hepatocyte polarity in embryonic liver tissue, converting BC into epithelial tubes. Our results suggest that apical bulkheads are cell-intrinsic anisotropic mechanical elements that determine the elongation of BC during liver tissue morphogenesis.

Specificities of exosome versus small ectosome secretion revealed by live intracellular tracking of CD63 and CD9.

Despite their roles in intercellular communications, the different populations of extracellular vesicles (EVs) and their secretion mechanisms are not fully characterized: how and to what extent EVs form as intraluminal vesicles of endocytic compartments (exosomes), or at the plasma membrane (PM) (ectosomes) remains unclear. Here we follow intracellular trafficking of the EV markers CD9 and CD63 from the endoplasmic reticulum to their residency compartment, respectively PM and late endosomes. We observe transient co-localization at both places, before they finally segregate. CD9 and a mutant CD63 stabilized at the PM are more abundantly released in EVs than CD63. Thus, in HeLa cells, ectosomes are more prominent than exosomes. By comparative proteomic analysis and differential response to neutralization of endosomal pH, we identify a few surface proteins likely specific of either exosomes (LAMP1) or ectosomes (BSG, SLC3A2). Our work sets the path for molecular and functional discrimination of exosomes and small ectosomes in any cell type.

Localized Intercellular Transfer of Ephrin-As by Trans-endocytosis Enables Long-Term Signaling.

Ephrins can elicit either contact-mediated cell-cell adhesion or repulsion, depending on the efficiency of the removal of their ligand-receptor complexes from the cell surface, thus controlling tissue morphogenesis and oncogenic development. However, the dynamic of the turnover of newly assembled ephrin-Eph complexes during cell-cell interactions remains mostly unexplored. Here, we show that ephrin-A1-EphA2 complexes are locally formed at the tip of the filopodia, at cell-to-cell contacts. Clusters of ephrin-A1 from donor cells surf on filopodia associated to EphA2-bearing subdomains of acceptor cells. Full-length ephrin-A1 is transferred to acceptor cells by trans-endocytosis through a proteolysis-independent mechanism. Trans-endocytosed ephrin-A1 bound to its receptor enables signaling to be emitted from endo-lysosomes of acceptor cells. Localized trans-endocytosis of ephrin-A1 sustains contact-mediated repulsion on cancer cells. Our results uncover the essential role played by local concentration at the tip of filopodia and the trans-endocytosis of full-length ephrin to maintain long-lasting ephrin signaling.

Encefalomielitis aguda diseminada en el adulto Caso de asociación con infección por el virus de la hepatitis A / Acute disseminated encephalomyelitis in adults Association with infection by hepatitis A virus

Resumen La encefalomielitis aguda diseminada (ADEM) es una enfermedad desmielinizante monofásica, queusualmente sigue a una infección o vacunación, principalmente por el virus del sarampión, y ocurre principalmente en niños y adultos jóvenes. Su asociación con la infección por el virus de la hepatitis A es rara, y se halla poco documentada. Se presenta el caso de una paciente femenina de 53 años con ADEM e infección por hepatitis A. Se resalta la inclusión de la hepatitis A dentro del tamiz causal de pacientes adultos con ADEM. (Acta Med Colomb 2014; 39: 64-68).

Abstract Acute disseminated encephalomyelitis (ADEM) is a monophasic demyelinating disease that usually follows an infection or vaccination, mainly by the measles virus and occurring primarily in children and young adults. His association with infection by hepatitis A virus is rare, and is poorly documented. The case of a 53 years old female patient with ADEM and infection by hepatitis A is presented. The inclusion of hepatitis A within the causal screening of adult patients with ADEM is highlighted. (Acta Med Colomb 2014; 39: 64-68).

Síndrome de Blesovsky Pseudotumor pulmonar infrecuente y subdiagnosticado / Blesovsky syndrome Uncommon and underdiagnosed pulmonary pseudotumor

Resumen Se presenta el caso de un hombre de 68 años inmunosuprimido, en periodo tardío postrasplante hepático por cirrosis alcohólica en quien se encuentra de manera incidental atelectasia redonda del pulmón en estudios imagenológicos. El paciente cursaba asintomático y como único hallazgo positivo al examen físico presentaba estertores finos basales. No fue posible encontrar factores etiológicos relacionados, por lo que se categorizó como un caso idiopático. (Acta Med Colomb 2013; 38: 258-261).

Abstract We present the case of a 68 year old immunosuppressed man, in the late period after liver transplant for alcoholic cirrhosis and in whom incidentally imaging studies showed a lung round atelectasis. The patient was asymptomatic and the only positive finding on physical examination was fine basal rales. It was impossible to find related etiological factors, so the case was categorized as idiopathic. (ActaMed Colomb 2013; 38: 258-261).

Costo-efectividad de la colecistectomía laparoscópica y de la abierta en una muestra de población colombiana / Cost-effectiveness of laparoscopic versus open cholecystectomy

Introducción. La colecistectomía ha sido objeto de varios estudios clínicos y de costos a nivelmundial. Objetivo. Evaluar el costo-efectividad de la colecistectomía abierta y de la laparoscópica desde laperspectiva del tercer pagador. Materiales y métodos. Se llevó a cabo un estudio de costo-efectividad en dos hospitales de Bogotá. Se obtuvieron los datos de efectividad de las cirugías a partir de un estudio de cohortes, y se obtuvo enforma retrospectiva el tipo de colecistectomía y en forma prospectiva, el resultado. Se incluyeron 376 pacientes intervenidos por colecistitis o litiasis de mayo de 2005 a junio de 2006; 156 pacientes fueron intervenidos por colecistectomía abierta y 220 por laparoscopia. Los resultados que se analizaron fueron los siguientes: frecuencia de complicaciones, estancia hospitalaria, reincorporación a las labores cotidianas y duración de la cirugía. Los costos se recolectaron según el tipo de estudio económico y sólo se incluyeron los costos directos. Posteriormente, se planteó un estudio de costo-efectividad a un año desde la perspectiva del tercer pagador; se propuso un modelo de árbol de decisiones y se calcularon las razones de incremento de costo-efectividad para cada uno de los desenlaces propuestos. Resultados. Los resultados de la colecistectomía abierta frente a la laparoscópica fueron: OR ajustado de complicaciones: 2,02 (IC95% 0,94-4,37); conversión quirúrgica (tasa): 3,2%; estancia: 2,2 Vs. 1,6,p=0,003; reincorporación a cotidianidad: 32,5 Vs. 9,6, p<0,001; duración quirúrgica: 22 minutos (p<0,001) menor en la colecistectomía abierta; desde la perspectiva del tercer pagador, costo promedio: US$995 Vs. US$ 1.048; incremento del costo-efectividad: US$ 7,4 favoreciendo la laparoscópica; desde la perspectiva paciente, costo promedio: US$ 53.2 Vs. US$ 104,8; incremento del costo-efectividad: US$-7.3 favoreciendo la laparoscópica; cero mortalidad. La variable que más impactó tiene en la toma de decisiones en términos de costos es el costo del procedimiento quirúrgico. Conclusiones. Hubo mayor estancia hospitalaria en la colecistectomía abierta frente a la mayor duración quirúrgica en la laparoscópica; en el costo directo de la laparoscópica: menor para IPS y pacientes; y en costo-efectividad equiparable para ambos procedimientos.

Introduction. Cholecystectomy has been the subject of several clinical and cost comparison studies. Objective. The results of open or laparoscopy cholecystectomy were compared in terms of cost and effectiveness from the perspective of health care institutions and from that of the patients. Materials and methods. The cost-effectiveness study was undertaken at two university hospitals in Bogotá, Colombia. The approach was to select the type of cholecystectomy retrospectively and then assess the result prospectively. The cost analysis used the combined approach of micro-costs and daily average cost. Patient resource consumption was gathered from the time of surgery room entry to time of discharge. A sample of 376 patients with cholelithiasis/cystitis (May 2005-June 2006) was selected--156 underwent open cholecystectomy and 220 underwent laparoscopic cholecystectomy. The following data were tabulated: (1) frequency of complications and mortality, post-surgical hospital stay, (2) reincorporation to daily activities, (3) surgery duration, (4) direct medical costs, (5) costs to the patient, and (6) mean and incremental cost-effectiveness ratios. Results. Frequency of complications was 13.5% for open cholecystectomy and 6.4% for laparoscopic cholecystectomy (p=0.02); hospital stay was longer in open cholecystectomy than in laparoscopic cholecystectomy (p=0.003) as well as the reincorporation to daily activities reported by the patients (p<0.001). The duration of open cholecystectomy was 22 min longer than laparoscopic cholecystectomy (p<0.001). The average cost of laparoscopic cholecystectomy was lower than open cholecystectomyand laparoscopic cholecystectomy was more cost-effective than open cholecystectomy (US$ 995 vs. US$ 1,048, respectively). The patient out-of-pocket expenses were greater in open cholecystectomy compared to laparoscopic cholecystectomy (p=0.015). Mortality was zero. Conclusions: The open laparoscopy procedure was associated with longer hospital stays, where asthe cholecystectomy procedure required a longer surgical duration. The direct cost of the latter was lower for both for the health care institution and patients. The cost-effectiveness for both procedures was comparable.

[Cost-effectiveness of laparoscopic versus open cholecystectomy]. / Costo-efectividad de la colecistectomía laparoscópica y de la abierta en una muestra de población colombiana.

INTRODUCTION: Cholecystectomy has been the subject of several clinical and cost comparison studies. OBJECTIVE: The results of open or laparoscopy cholecystectomy were compared in terms of cost and effectiveness from the perspective of health care institutions and from that of the patients. MATERIALS AND METHODS: The cost-effectiveness study was undertaken at two university hospitals in Bogotá, Colombia. The approach was to select the type of cholecystectomy retrospectively and then assess the result prospectively. The cost analysis used the combined approach of micro-costs and daily average cost. Patient resource consumption was gathered from the time of surgery room entry to time of discharge. A sample of 376 patients with cholelithiasis/cystitis (May 2005-June 2006) was selected--156 underwent open cholecystectomy and 220 underwent laparoscopic cholecystectomy. The following data were tabulated: (1) frequency of complications and mortality, post-surgical hospital stay, (2) reincorporation to daily activities, (3) surgery duration, (4) direct medical costs, (5) costs to the patient, and (6) mean and incremental cost-effectiveness ratios. RESULTS: Frequency of complications was 13.5% for open cholecystectomy and 6.4% for laparoscopic cholecystectomy (p=0.02); hospital stay was longer in open cholecystectomy than in laparoscopic cholecystectomy (p=0.003) as well as the reincorporation to daily activities reported by the patients (p<0.001). The duration of open cholecystectomy was 22 min longer than laparoscopic cholecystectomy (p<0.001). The average cost of laparoscopic cholecystectomy was lower than open cholecystectomy and laparoscopic cholecystectomy was more cost-effective than open cholecystectomy (US$ 995 vs. US$ 1,048, respectively). The patient out-of-pocket expenses were greater in open cholecystectomy compared to laparoscopic cholecystectomy (p=0.015). Mortality was zero. CONCLUSIONS: The open laparoscopy procedure was associated with longer hospital stays, where as the cholecystectomy procedure required a longer surgical duration. The direct cost of the latter was lower for both for the health care institution and patients. The cost-effectiveness for both procedures was comparable.

Percepciones de los trabajadores del sector salud frente a Internet y las tecnologías móviles en Colombia / Health care workers' perception of the Internet and mobile technologies in Colombia

In July 2007 in Medellín, Colombia, 1 200 health care professionals were asked to complete a questionnaire: of the 493 who participated, the mean age was 31.2 years; 58.8 percent were physicians; and 97.6 percent had Internet access, 60.5 percent on a daily basis and 27.7 percent, weekly. The preferred place to access the Internet was from home (58 percent) or from the work place (12.5 percent); 98 percent reported having a cell phone, and of those, 80 percent were interested in using health education tools via cell phone. These are the first data published regarding Internet and cellular phone penetration among health care workers in Colombia. Acceptance of the Internet and mobile systems as health information tools is gaining, and as such, creating a new opportunity for training and harnessing of these new technologies.