Identification of stem cells in small intestine and colon by marker gene Lgr5

The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. It is currently believed that four to six crypt stem cells reside at the +4 position immediately above the Paneth cells in the small intestine; colon stem cells remain undefined. Lgr5 (leucine-rich-repeat-containing G-protein-coupled receptor 5, also known as Gpr49) was selected from a panel of intestinal Wnt target genes for its restricted crypt expression. Here, using two knock-in alleles, we reveal exclusive expression of Lgr5 in cycling columnar cells at the crypt base. In addition, Lgr5 was expressed in rare cells in several other tissues. Using an inducible Cre knock-in allele and the Rosa26-lacZ reporter strain, lineage-tracing experiments were performed in adult mice. The Lgr5-positive crypt base columnar cell generated all epithelial lineages over a 60-day period, suggesting that it represents the stem cell of the small intestine and colon. The expression pattern of Lgr5 suggests that it marks stem cells in multiple adult tissues and cancers.     

Dynamics of human adipose lipid turnover in health and metabolic disease

Adipose tissue mass is determined by the storage and removal of triglycerides in adipocytes. Little is known, however, about adipose lipid turnover in humans in health and pathology. To study this in vivo, here we determined lipid age by measuring (14)C derived from above ground nuclear bomb tests in adipocyte lipids. We report that during the average ten-year lifespan of human adipocytes, triglycerides are renewed six times. Lipid age is independent of adipocyte size, is very stable across a wide range of adult ages and does not differ between genders. Adipocyte lipid turnover, however, is strongly related to conditions with disturbed lipid metabolism. In obesity, triglyceride removal rate (lipolysis followed by oxidation) is decreased and the amount of triglycerides stored each year is increased. In contrast, both lipid removal and storage rates are decreased in non-obese patients diagnosed with the most common hereditary form of dyslipidaemia, familial combined hyperlipidaemia. Lipid removal rate is positively correlated with the capacity of adipocytes to break down triglycerides, as assessed through lipolysis, and is inversely related to insulin resistance. Our data support a mechanism in which adipocyte lipid storage and removal have different roles in health and pathology. High storage but low triglyceride removal promotes fat tissue accumulation and obesity. Reduction of both triglyceride storage and removal decreases lipid shunting through adipose tissue and thus promotes dyslipidaemia. We identify adipocyte lipid turnover as a novel target for prevention and treatment of metabolic disease.     

Eine Methode zur Durchführung vonin-vivo-Messungen bei Indikator-Untersuchungen mit radioaktiven Isotopen

Summary Anin-vivo-method is described measuring the activity of an exactly defined part of a greater system by means of a coincidence circuit, using only radioactive isotopes emitting two or more gamma-quanta per decay. The number of accidental coincidences can be made as small as necessary by means of a sufficiently short resolving-time (scintillation-counters).     

When Research and Practice Collide: The Role of Action Research When There Is a Conflict of Interest with Stakeholders

This article discusses problematic aspects of the role of the action researcher when working with multiple stakeholders on a complex research project concerning regional development. The case presented here deals with the improvement of the regional innovation system in a small region in the south of Norway. The project resulted in a conflict between stakeholders and the action research (AR) team. We claim that when working in a regional context, the role of the action researcher is set to be a collaborator in a context of power play; the ultimate stakeholders must be defined as the citizens in that region. Therefore, in some situations the action researcher must have a legitimatised right to abandon collaboration and present a critical voice in the public deliberation. Strategic power play and strategic action by stakeholders represent a clear threat to the soft approach of collaboration, reflectivity, and democratic dialogue that AR represents. The ultimate challenge and obligation of the action researcher is to improve democracy in society in a long-term perspective through representing a critical capacity in the public deliberation.