RESUMEN
OBJECTIVES: To reveal the gene expression profile and pathways involved in host-tumor interactions in a rat orthotopic syngeneic bladder cancer model. METHODS: Rat bladder cancer cells (AY-27 cell line) were inoculated intravesically into female Fischer rats. The bladders were analyzed at 7, 14, and 28 days by histologic examination and at 14 days with Affymetrix GeneChip with a newly developed bioinformatics program for the Kyoto Encyclopedia of Genes and Genomes (KEGG). RESULTS: The cancer had developed into Stage Ta and carcinoma in situ (Tis) after 7 days, Stage T1 after 14 days, and Stage T3 after 28 days in the bladder. At 14 days, >4000 genes were found to be differentially expressed and 20 KEGG pathways were actively involved in the bladder. The molecular pathway for (human) bladder cancer development was activated, and, at the same time, pathways in connection with the host immune responses were altered, including antigen processing and presentation, the T-cell receptor signaling pathway, natural killer cell-mediated cytotoxicity, the Toll-like receptor signaling pathway, and the B-cell receptor signaling pathway. Moreover, the cell adhesion molecules associated with the immune system were upregulated, but those associated with the neural system were downregulated. CONCLUSIONS: The bladder cancer developed aggressively despite active host immune responses. Conceivably, the cancer immunoediting process is associated with the progression of bladder cancer in this model.
Asunto(s)
Perfilación de la Expresión Génica , Neoplasias de la Vejiga Urinaria/genética , Animales , Femenino , Ratas , Ratas Endogámicas F344RESUMEN
BACKGROUND: The Medical Student Research Programme is a national education and grant scheme for medical students who wish to carry out research in parallel with their studies. The purpose of the programme is to increase recruitment of people with a standard medical degree to medical research. The Research Programme was established in 2002 and underwent a thorough evaluation during the spring of 2007. The evaluation should investigate if the programme had fulfilled its objectives of increased recruitment to medical research, in addition to the students' and supervisors' satisfaction of the programme, and unwanted differences between the universities. METHODS: Data was collected from students, supervisors and administrative staff via web-based questionnaires. Information about admission, implementation, results achieved and satisfaction was analysed and compared between the four Norwegian medical schools. In addition, the position of the scheme in relation to the national Quality Reform of Higher Education was analysed. RESULTS: At the end of 2006, the Medical Student Research Programme had recruited 265 medical students to research. These consisted of 214 active students, 35 who had completed their studies and only 17 who had dropped out. Both students and supervisors were generally very satisfied with the scheme, including the curriculum, the results achieved and the administrative service. The majority of students wanted to continue their research towards a PhD and, of those who had completed the Medical Student Research Programme, practically all had published one or several scientific papers. The survey showed only small differences between the four medical schools, despite their choice of somewhat different solutions in terms of administration and organisation. The Medical Student Research Programme satisfies the majority of the demands of the Quality Reform, however as an integrated research programme aimed at a PhD it presupposes access to PhD courses before the completion of medical studies, as well as the ability to include undergraduate scientific work in a PhD thesis. CONCLUSION: The Medical Student Research Programme has led to an increase in the recruitment of graduated physicians to medical research in Norway. It will only be possible to evaluate whether this in turn will result in a larger number of PhDs in 3-5 years; this will also depend on the access to grants and fellowships.
Asunto(s)
Academias e Institutos/estadística & datos numéricos , Investigación Biomédica , Selección de Profesión , Movilidad Laboral , Educación de Postgrado/estadística & datos numéricos , Estudiantes de Medicina , Análisis de Varianza , Actitud del Personal de Salud , Recolección de Datos , Escolaridad , Humanos , Motivación , Noruega , Selección de Personal , Evaluación de Programas y Proyectos de Salud , Encuestas y CuestionariosRESUMEN
BACKGROUND: It is a common dogma that gastric bypass (GB) induces early satiety and consequent reductions in food intake and nutrient absorption. The aim of the present study was to analyze feeding behavioral and metabolic changes in rats after GB. METHODS: Male Sprague-Dawley rats at the ages of 23 and 42 weeks were placed in metabolic cages connected with a comprehensive laboratory animal monitoring system. At the age of 48 weeks they were subjected to either GB or sham operation, and then placed in metabolic cages at 51 and 62 weeks (or 3 and 14 weeks postoperatively). RESULTS: GB rats lost 20% of the body weight within 2-3 weeks and remained at this lower level until the end of the study at 14 weeks postoperatively. Satiety ratio was higher during daytime than nighttime in both sham-operated and GB rats, but was not significantly different between the two groups. Neither daily accumulated food intake nor food intake per 100 g of body weight was different between sham-operated and GB rats. Apparently, GB rats ate more frequently during daytime and had smaller meal size during nighttime at 3 weeks postoperatively. These changes were not present at 14 weeks postoperatively. Energy density in the feces was the same in GB and sham-operated rats postoperatively. Energy expenditure declined with age, but increased in GB rats compared with age-matched sham-operated rats. CONCLUSIONS: GB reduced the body weight without causing early satiety, reducing food intake or inducing malabsorption. It did, however, increase energy expenditure.
Asunto(s)
Ingestión de Energía , Conducta Alimentaria , Derivación Gástrica , Pérdida de Peso , Animales , Apetito , Metabolismo Energético , Masculino , Ratas , Ratas Sprague-Dawley , Saciedad , Factores de TiempoRESUMEN
Bariatric surgery (Roux-en-Y or mini-gastric bypass) is designed to limit food intake by creating a small gastric pouch and to reduce nutrient absorption by bypassing the long limb of the intestine. We report 1-year follow-up results after micro-gastric bypass in rats. Micro-gastric bypass was performed by anastomosis of the esophagus and the proximal jejunum. Body weight, body composition, bone mineral density, food intake, and serum levels of ghrelin and obestatin were measured. Growing rats had a 40% weight reduction 2 months after micro-gastric bypass surgery compared to 20% after gastrectomy and 30% after stomach bypass (anastomosis of the esophagus and duodenal bulb). Six months after micro-gastric bypass surgery, the rats stopped growing compared to controls that gained continuously due to expansion of the fat compartment. Adult rats (600 g) lost 30% of their body weight 5 months after the micro-gastric bypass, while food intake was not reduced. Serum levels of obestatin (but not ghrelin) were reduced in rats with micro-gastric bypass. The results suggest that micro-gastric bypass efficiently reduced body weight, particularly fat mass; loss of the weight after micro-gastric bypass was not due to reduced food intake; and lean tissue and bone development were impaired in growing subjects after gastric bypass.
Asunto(s)
Derivación Gástrica/métodos , Pérdida de Peso , Anastomosis Quirúrgica , Animales , Metabolismo Energético , Esófago/cirugía , Estudios de Seguimiento , Ghrelina , Yeyuno/cirugía , Masculino , Hormonas Peptídicas/sangre , Ratas , Ratas Sprague-DawleyRESUMEN
OBJECTIVE: Enterochromaffin (EC) cells in the gastrointestinal tract have an important function as regulators of secretion, motility and sensation. The EC cell has traditionally been described as bottle-shaped, with basally located stores of serotonin. Stimuli acting on the apical membrane trigger serotonin release, which in turn activates the subepithelial sensory nerve terminals. To better describe the appearance of EC cells, we developed a new method for visualization of mucosal cells. MATERIAL AND METHODS: The stomach, small intestine and large intestine were excised from Sprague-Dawley rats and then fixed in formalin. The organs were everted and filled with pronase solution. Single cells and aggregates of formalin-fixed mucosal cells were collected by scraping the mucosa off the muscularis mucosa. EC cells were visualized by staining for immunoreactivity against serotonin. RESULTS: EC cells with luminal extensions and very long (up to 80 microM) basally located axon-like extensions, sometimes connecting to neuron-like structures, were found. Other EC cells had no or only short and blunt basal extensions. Dividing serotonin-containing EC cells were also seen. CONCLUSIONS: These findings could make an important contribution towards furthering our understanding of EC cell function in gastrointestinal physiology. This new method can also readily be used to give better visualization of the morphology of other mucosal cells.
Asunto(s)
Células Enterocromafines/citología , Mucosa Gástrica/citología , Mucosa Intestinal/citología , Animales , Separación Celular/métodos , Fijadores Externos , Femenino , Técnicas Histológicas , Inmunohistoquímica , Intestino Grueso/citología , Intestino Delgado/citología , Ratas , Ratas Sprague-Dawley , Serotonina/análisis , Coloración y Etiquetado , Fijación del Tejido/métodosRESUMEN
BACKGROUND: The rationale for bariatric surgery is to reduce food intake by gastric restriction and/or malabsorption by intestinal bypass. Unlike ghrelin, gastrin is released in response to food intake. Here we studied the possible role of gastrin in the reduction of body weight after gastric bypass surgery. METHODS: Rats were divided into four experimental groups and were subjected to different treatments: sham operation, gastric bypass, sham operation + gastrin infusion, and gastric bypass + gastrin infusion. The gastric bypass was done by anastomosing the esophagus to the duodenal bulb without bypassing the intestine. Gastrin-17 was infused continuously for 2 months via subcutaneously implanted osmotic minipumps. Body weights were recorded; serum gastrin and ghrelin levels were measured, and the stomachs were analyzed morphologically. RESULTS: Gastric bypass resulted in reducing the body weight, stomach weight, thickness of the oxyntic mucosa, serum gastrin concentration, and activity of the ECL cells. Gastrin infusion prevented mucosal atrophy and ECL cell inactivation, and attenuated the body weight reduction that occurred following gastric bypass. Circulating ghrelin and ghrelin-producing A-like cells in stomachs that had undergone gastric bypass were unchanged with or without gastrin infusion and are thus unlikely to be responsible for the reduced body weight. CONCLUSION: We suggest that hypogastrinemia and impaired ECL cell function in the oxyntic mucosa of the stomach might be partially responsible for the reduction in body weight that occurs after gastric bypass.
Asunto(s)
Derivación Gástrica/métodos , Gastrinas/sangre , Pérdida de Peso/fisiología , Anastomosis Quirúrgica , Animales , Duodeno/cirugía , Células Enterocromafines/fisiología , Esófago/cirugía , Mucosa Gástrica/citología , Mucosa Gástrica/fisiología , Gastrinas/farmacología , Ghrelina , Bombas de Infusión Implantables , Masculino , Tamaño de los Órganos , Células Parietales Gástricas/fisiología , Hormonas Peptídicas/sangre , Ratas , Ratas Sprague-Dawley , Pérdida de Peso/efectos de los fármacosRESUMEN
Urinary bladder augmentation with a segment of the stomach, i.e., gastrocystoplasty, has been used to improve capacity and compliance in patients with bladder dysfunction. In the present study, rats were subjected to gastrocystoplasty (using the oxyntic segment) with or without fundectomy (removal of the oxyntic part of stomach), and the acid secretion in the augmented bladder was measured. In freely fed rats, the pH values were neutral and not significantly decreased in the rats subjected to gastrocystoplasty with or without fundectomy compared to controls (no operation or sham operation). In response to food intake after being fasted, the rats subjected to gastocystoplasty + fundectomy produced significant amounts of acid. Immunohistochemical examination revealed that the ECL cells and parietal cells seemed to be normal in rats with gastrocystoplasty alone, and that micronodules of ECL appeared to develop in rats with gastrocystoplasty + fundectomy. We suggest that the rats subjected to gastrocystoplasty + fundectomy are capable of producing acid secretion in the bladder, probably due to the secretagogue and trophic effects of gastrin on the ECL cells in the segment of the oxyntic mucosal segment of the bladder.
Asunto(s)
Jugo Gástrico/metabolismo , Vejiga Urinaria/metabolismo , Procedimientos Quirúrgicos Urológicos/métodos , Animales , Ingestión de Alimentos/fisiología , Células Similares a las Enterocromafines/metabolismo , Células Similares a las Enterocromafines/patología , Células Similares a las Enterocromafines/trasplante , Femenino , Fundus Gástrico/metabolismo , Fundus Gástrico/fisiopatología , Fundus Gástrico/cirugía , Células Secretoras de Gastrina/metabolismo , Células Secretoras de Gastrina/trasplante , ATPasa Intercambiadora de Hidrógeno-Potásio/metabolismo , Histidina Descarboxilasa/metabolismo , Concentración de Iones de Hidrógeno , Inmunohistoquímica/métodos , Células Parietales Gástricas/metabolismo , Células Parietales Gástricas/trasplante , Ratas , Ratas Sprague-Dawley , Tasa de Supervivencia , Factores de Tiempo , Vejiga Urinaria/fisiopatología , Vejiga Urinaria/cirugía , Micción , Procedimientos Quirúrgicos Urológicos/mortalidadRESUMEN
BACKGROUND: The purpose of this study was to investigate whether rats dosed with serotonin develop changes similar to those seen in human carcinoid heart disease. METHODS AND RESULTS: Ten Sprague-Dawley rats were given serotonin injections subcutaneously once daily for 3 months; controls were given saline. A long-lasting hyperserotoninemia with a >10-fold increase in both platelet-poor plasma and dialysate from the femoral muscles appeared. The animals developed clinical signs such as flushing and loose stools. After 3 months, 6 of 10 rats given serotonin had pathological echocardiographs. Two animals had a combination of aortic and pulmonary valve insufficiency, 1 had isolated aortic valve insufficiency, and 3 had isolated pulmonary valve insufficiency. Histopathological examination revealed shortened and thickened aortic cusps and carcinoidlike plaques characterized by a collection of myofibroblasts within an extracellular matrix of collagen ground substance. Immunostaining for Ki-67 demonstrated an increased number of proliferating subendocardial cells. In the control group, no pathological changes were seen. With the use of reverse-transcription polymerase chain reaction, normal rat aortic cusps were shown to express mRNA for serotonin receptors 5-HT1A, 5-HT2A, and 5-HT2B and the serotonin transporter 5-HTT. CONCLUSIONS: For the first time, long-term serotonin administration was performed in rats. Morphological and echocardiographic changes similar to those seen in human carcinoid heart disease developed. This study demonstrates that serotonin most likely is involved in the pathogenesis of carcinoid heart disease.
Asunto(s)
Modelos Animales de Enfermedad , Enfermedades de las Válvulas Cardíacas/inducido químicamente , Serotonina/administración & dosificación , Animales , Cardiopatía Carcinoide/inducido químicamente , Cardiopatía Carcinoide/patología , Cardiopatía Carcinoide/fisiopatología , Electrocardiografía , Matriz Extracelular/química , Fibroblastos/patología , Enfermedades de las Válvulas Cardíacas/patología , Antígeno Ki-67/análisis , Glicoproteínas de Membrana/genética , Proteínas de Transporte de Membrana/genética , Proteínas del Tejido Nervioso/genética , ARN Mensajero/análisis , Ratas , Ratas Sprague-Dawley , Receptores de Serotonina/genética , Serotonina/sangre , Serotonina/farmacología , Proteínas de Transporte de Serotonina en la Membrana Plasmática , Factores de TiempoRESUMEN
The paper describes the use of laser-assisted microdissection to retrieve microscopically defined cell populations including single cells from tissue sections for subsequent analysis of genomic DNA and mRNA. A general background is given on the techniques available and requirements for PCR based on minute templates. Different pre-PCR approaches are briefly described and possibilities and limitations of using archival material compared to fresh frozen tissue are discussed. In the article we give one example on how we have used the PALM laser microscopy system in combination with a nested, multiplex PCR system to analyze single normal keratinocytes as well as tumor cells from a case of basal cell cancer. We found that p53 mutations are common in normal, chronically sun-exposed skin. Widespread yet common mutations in the p53 gene that were unrelated to immunoreactivity for the p53 antibody were found in tumor cells. In addition there were rare mutations in occasional tumor cells that apparently did not result in selective growth advantage. Perspectives for the future are presented and the potential of laser assisted microdissection is highlighted within the fields of cancer research, developmental studies as well as studies of inflammatory and degenerative diseases. The combination of a method that allows careful selection of defined cells with powerful micro array based techniques, provides a setting with potential to uncover pathogenic mechanisms for large variety of human diseases.
Asunto(s)
Técnicas Citológicas/métodos , Rayos Láser , Microscopía Confocal/métodos , Biología Molecular/tendencias , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Técnicas Citológicas/instrumentación , Técnicas Citológicas/tendencias , Genes p53/genética , Humanos , Microscopía Confocal/instrumentación , Microscopía Confocal/tendencias , Mutación , Neoplasias/genética , Neoplasias/ultraestructura , Análisis de Secuencia por Matrices de Oligonucleótidos/instrumentación , Análisis de Secuencia por Matrices de Oligonucleótidos/tendencias , Reacción en Cadena de la Polimerasa , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/ultraestructura , Manejo de EspecímenesRESUMEN
Gastrin plays a crucial role in maintaining a normal cellular composition and function of the oxyntic mucosa. It has been debated for decades whether parietal cells possess cholecystokinin-2 (CCK(2)) receptors and interact directly with gastrin. We investigated whether parietal cells express CCK(2) receptor mRNA by using new molecular biology techniques. Rat oxyntic mucosal cells were dispersed and enriched by elutriation, and single parietal and ECL cells were isolated from cell smears by means of laser microbeam microdissection and laser pressure catapulting. The mRNA from each single cell was isolated and subjected to one-step multiplex or conventional reverse transcription-polymerase chain reaction and subsequent nested PCR. Specific primers for the CCK(2) receptor were used in combination with primers for H,K-ATPase and histidine decarboxylase, specific markers for parietal and ECL cells, respectively. CCK(2) receptor mRNA was detected in 25% of the rat parietal cells and 40% of the ECL cells examined.
Asunto(s)
Disección/métodos , Perfilación de la Expresión Génica , Rayos Láser , Células Parietales Gástricas/metabolismo , Receptores de Colecistoquinina/metabolismo , Animales , Femenino , Células Parietales Gástricas/citología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptor de Colecistoquinina B , Receptores de Colecistoquinina/genéticaRESUMEN
The role of the gastric acid secretagogues acetylcholine, gastrin and histamine has been debated for decades. Initially, the mast cell was considered the source of acid stimulatory histamine. Later, Håkanson & Owman (1969) showed that the entero-chromaffinlike (ECL) cell produces and stores histamine in several species, including rat and man. Kahlson et al. (1964) showed that food and gastrin stimulated oxyntic mucosal histamine synthesis and release, Berglindh et at. (1976) that histamine and cholinergics but not gastrin induced acid secretion in isolated oxyntic glands and parietal cells, and Rangachari (1995) that acetylcholine or gastrin released histamine in isolated mucosa. These findings suggested that gastrin stimulates acid secretion through release of ECL cell histamine. Studying simultaneous histamine release and acid secretion in isolated oxyntic mucosal cells, we found that gastrin stimulated acid secretion only in preparations releasing histamine. Moreover, in the isolated rat stomach, gastrin stimulated both histamine release and acid secretion. Maximal acid output was higher with histamine than with gastrin, and augmented by acetylcholine but not by gastrin. These findings strongly suggested that gastrin acts by releasing histamine. Finally, a fluorescein-labelled gastrin analogue bound to the ECL cell, not to the parietal or stem cell regions. This is interesting, recalling that gastrin has a potent and specific trophic effect on the ECL cell and only a general effect on all other oxyntic cell types. In conclusion, physiological observations are best explained by localising the CCK2 receptor only to the ECL cell, the other effects of gastrin on the gastric mucosa being secondary to the release of mediators from the ECL cell.