Adhesive and invasive characteristics appear to be crucial for organ-specific metastasis formation. Using intravital microscopy we investigated the relation between the metastatic potential of colon carcinoma cells and their adhesive and invasive behavior during early steps of metastasis within microvasculatures of rat liver, lung, intestine, skin, muscle, spleen, and kidney in vivo. Colorectal carcinomas will affect ϳ6% of the population in the Western countries during their lifetime. These carcinomas are the third leading cause of cancer-related deaths among women and men and are the most important malignancies of the gut.1 Approximately 50% of the cancer patients die within 5 years because of cancerrelated problems, mostly attributable to metastatic lesions caused by the spread of cancers to near and distant sites. Even after potentially curative surgery, more than 30% of the patients with colorectal carcinomas subsequently develop metastases demonstrating that the spread from primary tumors to distant organs is usually the life-limiting aspect in colorectal carcinoma patients. 2Similar to other cancer entities, colorectal carcinomas often show organ preference of metastasis formation. The liver is the most common organ in which colorectal carcinomas establish distant metastases, and the liver is involved in more than 70% of patients with colorectal metastases. However, in 40 to 50% of these patients with liver metastases, other organs are also involved in metastatic colonization. The second most important organ for colorectal cancer metastasis is the lung, and 20 to 30% of all distant colorectal carcinoma metastases are found primarily in the lung. Isolated lung metastases with no evidence of other organ involvement are found in 5 to 10% of colorectal cancer patients. Other organs, such as the central nervous system, adrenal glands, spleen, skeleton, or skin together account for less than 10% of all colorectal metastases. 2,3The metastatic process consists of a number of sequential, interrelated steps that can all be rate limiting. 4,5 An important and early step during formation of distant metastasis appears to be the arrest of circulating tumor cells within the host organ.6,7 Approximately a century ago, two major hypotheses on the mechanisms of tumor cell arrest in metastatic host organs were proposed. Ewing 8 assumed that the random mechanical lodgment of Supported by the Innovative Medizinische Forschung Fund (University Hospital Mü nster) (Ha 1 2 01 01 to J.H.).K.S. and P.G. contributed equally to this study.

Objective: This international multicenter study by the Upper GI International Robotic Association aimed to gain insight in current techniques and outcomes of RAMIE worldwide. Background: Current evidence for RAMIE originates from single-center studies, which may not be generalizable to the international multicenter experience. Methods: Twenty centers from Europe, Asia, North-America, and South-America participated from 2016 to 2019. Main endpoints included the surgical techniques, clinical outcomes, and early oncological results of ramie. Results: A total of 856 patients undergoing transthoracic RAMIE were included. Robotic surgery was applied for both the thoracic and abdominal phase (45%), only the thoracic phase (49%), or only the abdominal phase (6%). In most cases, the mediastinal lymphadenectomy included the low paraesophageal nodes (n=815, 95%), subcarinal nodes (n = 774, 90%), and paratracheal nodes (n = 537, 63%). When paratracheal lymphadenectomy was performed during an Ivor Lewis or a McKeown RAMIE procedure, recurrent laryngeal nerve injury occurred in 3% and 11% of patients, respectively. Circular stapled (52%), hand-sewn (30%), and linear stapled (18%) anastomotic techniques were used. In Ivor Lewis RAMIE, robot-assisted hand-sewing showed the highest anastomotic leakage rate (33%), while lower rates were observed with circular stapling (17%) and linear stapling (15%). In McKeown RAMIE, a hand-sewn anastomotic technique showed the highest leakage rate (27%), followed by linear stapling (18%) and circular stapling (6%). Conclusion: This study is the first to provide an overview of the current techniques and outcomes of transthoracic RAMIE worldwide. Although these results indicate high quality of the procedure, the optimal approach should be further defined.

The remarkable capacity of the liver to regenerate after injury and the prospects of organ self-renewal have attracted much interest in the understanding and modulation of the underlying molecular events. We investigated the effect of mammalian target of rapamycin (mTOR) inhibitor rapamycin (RAPA) on liver by correlating intravital microscopy, immunohistochemistry, and reverse transcriptase polymerase chain reaction in a rat model of 2/3 hepatectomy. RAPA significantly retarded proliferation of hepatocytes, endothelial cells, and hepatic stellate cells (HSCs) mostly between days 2 and 4 after hepatectomy and downregulated major cytokines and growth factors (tumor necrosis factor alpha, hepatocyte growth factor, platelet-derived growth factor, platelet-derived growth factor receptor, insulin-like growth factor-1, transforming growth factor beta 1) important for liver regeneration. These effects were almost absent at later time points. RAPA also had a transient, but broad effect on angiogenesis, and impaired sinusoidal density as well as mRNA levels of vascular endothelial growth factor, vascular endothelial growth factor receptor 1, vascular endothelial growth factor receptor 2, and angiopoietin-1. Activation of HSC was also transiently suppressed as observed by smooth muscle protein 1 alpha protein expression and intercellular adhesion molecule-1 mRNA levels. The rate of apoptosis in liver was significantly increased by RAPA between day 3 and day 7. The effect of RAPA on liver repair, angiogenesis, and HSC activation is confined to the phase of active cell proliferation. This transient effect might allow further exploration of mTOR inhibitors in clinical situations that involve liver regeneration, and seems to have implications beyond immunosuppression.

During the education of the next generation of scientists in experimental research, careful instruction in surgical techniques is of major importance. This applies in particular to complicated microsurgical models, which require a structured teaching concept with clearly laid-down working steps and adequate didactic resources. Transplantations in rats are undoubtedly among the most difficult models in experimental surgery. Because completely sutured orthotopic liver transplantation and kidney transplantation have been practiced for many years in our Surgical Research Unit, techniques must be transmitted to future generations. A microsurgical training program has been set up with the aim of being efficient, transparent, and motivating. Simply learning-by-doing in the sense of "laissez-faire" is ineffective and costly. Our training program is based on "three-phase didactics," in which the learning targets are presented in sequence and are clearly defined. This report is intended to give a brief overview of the principal transplantation models and to serve as a guide for teaching these models.

Non-alcoholic fatty liver disease (NAFLD) is a common problem with a wide variety of phenotypes. While its pathogenesis is still not fully understood, several risk factors for disease progression have been identified. Therefore, defining adequate animal models may serve to unreveal the pathogenesis in NAFLD. We studied Lewis and Sprague-Dawley rats of both genders (n ¼ 6) fed standard (Std) or high-fat (HF) diet for three weeks. Disease stage was assessed by haematoxylin -eosin, Azan Heidenheim and Oil-Red staining, apoptosis by single-stranded DNA (ssDNA) detection and liver regeneration by Ki-67 staining. Serum markers of liver injury and lipid metabolism including adipocytokines were analysed. Livers of both strains and genders fed with HF diet demonstrated evidence of steatosis. Lewis rats developed microvesicular steatosis whereas Sprague-Dawley rats presented macrovesicular steatosis accompanied by pronounced fibrosis. Female gender of both strains was associated with lower steatosis grade and higher proliferation rate (P , 0.05). Gender-specific differences were most prominent in Lewis rats on a HF diet, where females showed lower alkaline phosphatase, cholesterol, triglyceride and leptin levels and a more favourable low-density lipoprotein/high-density lipoprotein ratio than males (P , 0.05). Reverse transcriptase-polymerase chain reaction analysis was performed to demonstrate changes in expression of various genes important for liver regeneration, fibrosis and steatosis. HF diet induced downregulation of proangiogenic genes such as vascular endothelial growth factor receptor 1 and 2 (P , 0.05) in males was not present in females. In conclusion, strain and gender served major roles in disease progression. These differences should be considered when designing studies and may offer new ways to advance therapeutic strategies.Keywords: NAFLD, steatosis, rat strain, gender differences, high-fat diet Laboratory Animals 2013; 47: 43-52. DOI: 10.1177/0023677212473717The increasing burden of non-alcoholic fatty liver disease (NAFLD) has resulted in greater attention towards its associated rise in morbidity and mortality. Even children can be affected. Among the various risk factors identified so far, a high-fat (HF) diet is one major prerequisite.1 The spectrum of NAFLD ranges from bland fatty infiltration to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis and can eventually lead to end-stage liver disease with an increased risk of hepatocellular carcinoma.2 Our current understanding of the pathogenesis may be explained by the two-hit hypothesis, where steatosis induced by increased fatty acid synthesis and hepatic uptake is followed by oxidative stress and release of proinflammatory and profibrogenic mediators. Gender-specific differences in prevalence, degree of liver injury and adipocytokine levels of adolescents with NAFLD have been reported. 4 In general, NAFLD is more common in men than in women and a reversal in gender distribution following menopause suggests an oestrogen-mediated protec...