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Study of the crosstalk between hepatocytes and endothelial cells using a novel multicompartmental bioreactor: a comparison between connected cultures and cocultures
No full textThe liver and other organs are connected to each other through the bloodstream. Therefore, the connection between tissues is generally mediated by soluble molecules able to cross the endothelial wall of capillaries. We developed a multicompartmental device, multicompartmental bioreactor (MCB), designed to mimic the connection between different tissues in which crosstalk is mediated by soluble molecules transported through the blood. A comparative study of the crosstalk between hepatocytes (HepG2) and endothelial cells (human umbilical vein endothelial cells) in connected culture in the MCB and in a traditional static coculture system was performed by analyzing glucose consumption and secretion of albumin, urea, and nitric oxide. When hepatocytes and endothelial cells were cultured together, the production of albumin and urea increased, and the increase was higher in the MCB than in traditional static coculture. In spite of this enhanced metabolic activity, the crosstalk between hepatocytes and endothelial cell leads to decreased glucose consumption with respect to hepatocytes alone, both in static and in dynamic conditions. However, the dynamic connected culture has a higher rate of metabolite synthesis and secretion with respect to cocultures. This means a more efficient use of energetic substrates and enhanced hepatocyte function in the MCB
Brain-gut-liver interactions across the spectrum of insulin resistance in metabolic fatty liver disease.
No full textBrain PET Imaging in Obesity and Food Addiction: Current Evidence and Hypothesis.
No full textThe ongoing epidemics of obesity is one main health concern of the present time. Overeating in some obese individuals shares similarities with the loss of control and compulsive behavior observed in drug-addicted subjects, suggesting that obesity may involve food addiction. Here, we review the contributions provided by the use of positron emission tomography to the current understanding of the cerebral control of obesity and food intake in humans. The available studies have shown that multiple areas in the brain are involved with the reward properties of food, such as prefrontal, orbitofrontal, somatosensory cortices, insula, thalamus, hypothalamus, amygdala, and others. This review summarizes the current evidence, supporting the concepts that i) regions involved in the somatosensory response to food sight, taste, and smell are activated by palatable foods and may be hyperresponsive in obese individuals, ii) areas controlling executive drive seem to overreact to the anticipation of pleasure during cue exposure, and iii) those involved in cognitive control and inhibitory behavior may be resistant to the perception of reward after food exposure in obese subjects. All of these features may stimulate, for different reasons, ingestion of highly palatable and energy-rich foods. Though these same regions are similarly involved in drug abusers and game-addicted individuals, any direct resemblance may be an oversimplification, especially as the heterogeneities between studies and the prevalent exclusion of sensitive groups still limit a coherent interpretation of the findings. Further work is required to comprehensively tackle the multifaceted phenotype of obesity and identify the role of food dependency in its pathophysiology. Copyright © 2012 S. Karger GmbH, Freibur
Metabolic control through hepatocyte and adipose tissue cross-talk in a multicompartmental modular bioreactor
No full textPhysiological processes involve a complex network of signaling molecules that act through paracrinal or endocrinal pathways; however, traditional in vitro models cannot mimic these interactions because of the lack of a dynamic cross-talk between cells belonging to different tissues. The multicompartmental modular bioreactor is a novel cell culture system where hepatocytes and adipose tissue are shown to interact in a more physiological manner. In the multicompartmental modular bioreactor, cells and tissues can be cultured in a common medium, which flows through the system acting as the bloodstream. Primary rat hepatocytes and adipose tissue were cultured separately and together in conventional conditions and in the bioreactor. Urea synthesis, albumin secretion, glycerol, free fatty acid, and glucose concentrations were analyzed and compared. The dynamic connected culture of adipose tissue and hepatocytes led to a significant enhancement of hepatic function in terms of increase of albumin and urea production with respect to conventional cultures. Interestingly, the glycerol gradually released from adipose tissue was buffered in the dynamic connected culture, manifesting a homeostatic-like control. These data show that the dynamic culture not only improves hepatocyte function, but also allows a cross-talk between tissues, leading to enhanced metabolic regulation in vitro
The interaction of blood flow, insulin, and bradykinin in regulating glucose uptake in lower-body adipose tissue in lean and obese subjects.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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