Insulin degradation by adipose tissue is increased in human obesity

White adipose tissue samples from obese and lean patients were used for the estimation ofinsulin protease and insulin:glutathione transhydrogenase using 1251-labeled insulin. There was no activity detected in the absence of reduced glutathione, which indicates that insulin is cleaved in human adipose "tissue through reduction of the disulfide bridge between the chains. O bese patients showed higher transhydrogenase activity (per U tissue protein wt, per U tissue wt, and in the total adipose tissue mass) than the lean group. There is a significant correlation between the activity per U tissue wt, and protein and total activity in the whole adipose tissue with respect to body mass index, with a higher activity in obese patients. The potential ofinsulin cleavage by adipose tissue in obese patients was a mean 5.6-fold higher than that in controla. The coexistence of high insulinemia and high cleavage capability implies that insulin secretion and turnover are increased in the o bese. Thus, white adipose tissue may be crucial in the control of energy availability through modulation ofinsulin cleavage

Methodological approaches to assess body-weight regulation and aetiology of obesity

Obesity, which is becoming one of the major health hazards in developed and developing societies, results from a long-term positive energy balance. Body-weight regulation and stability depend on an axis with three interrelated components: food intake, energy expenditure and adipogenesis, although there are still many unknown features concerning fuel homeostasis and energy balance. Biochemical processes are interconnected, and a separate consideration of each component is often useful for methodological purposes and to achieve a better understanding of the whole system. Thus, many different experimental approaches can be applied by using laboratory animals, cell culture or human subjects to unravel the molecular mechanisms which participate in body-weight regulation. Thus, both in vitro (cellular and subcellular models) and in vivo methods have dramatically increased our knowledge of weight control. Several strategies in obesity research are reported here, exploiting the opportunities of the molecular era as well as novel whole-body approaches, which will impact on the development of new targets for obesity management and prevention

Treatment of rats with a self-selected hyperlipidic diet, increases the lipid content of the main adipose tissue sites in a proportion similar to that of the lipids in the rest of organs and tissues

Adipose tissue (AT) is distributed as large differentiated masses, and smaller depots covering vessels, and organs, as well as interspersed within them. The differences between types and size of cells makes AT one of the most disperse and complex organs. Lipid storage is partly shared by other tissues such as muscle and liver. We intended to obtain an approximate estimation of the size of lipid reserves stored outside the main fat depots. Both male and female rats were made overweight by 4-weeks feeding of a cafeteria diet. Total lipid content was analyzed in brain, liver, gastrocnemius muscle, four white AT sites: subcutaneous, perigonadal, retroperitoneal and mesenteric, two brown AT sites (interscapular and perirenal) and in a pool of the rest of organs and tissues (after discarding gut contents). Organ lipid content was estimated and tabulated for each individual rat. Food intake was measured daily. There was a surprisingly high proportion of lipid not accounted for by the main macroscopic AT sites, even when brain, liver and BAT main sites were discounted. Muscle contained about 8% of body lipids, liver 1-1.4%, four white AT sites lipid 28-63% of body lipid, and the rest of the body (including muscle) 38-44%. There was a good correlation between AT lipid and body lipid, but lipid in"other organs" was highly correlated too with body lipid. Brain lipid was not. Irrespective of dietary intake, accumulation of body fat was uniform both for the main lipid storage and handling organs: large masses of AT (but also liver, muscle), as well as in the"rest" of tissues. These storage sites, in specialized (adipose) or not-specialized (liver, muscle) tissues reacted in parallel against a hyperlipidic diet challenge. We postulate that body lipid stores are handled and regulated coordinately, with a more centralized and overall mechanisms than usually assumed

Aportes al debate sobre investigación teórica o conceptual

This article aims to support the debate on the delimitation and scope of what in some research reports and in the existing bibliography has been nominated as theoretical research or conceptual research. Although several authors refer to this type of research, we have found ambiguities in the use of these terms, as well as non-specificities or overlaps in these nominations and in the connotations and classifications that underlie them. Some of the divergences found are those that tend to confuse conceptual research with qualitative research, bibliographic or documentary research, case studies, monographs or even far from being framed in a certain type of research, extending the confusion to concepts methodologies suchas theoretical framework or tracking of the state of the art.We propose to review the foundations, implications and specific scope of this particular type of research based on some epistemological and methodological reflectionsCet article vise à soutenir le débat sur la délimitation et la portée de ce qui dans certains rapports de recherche et dans la bibliographie existante a été nommé comme recherche théorique ou recherche conceptuelle. Bien que plusieurs auteurs se réfèrent à ce type de recherche, nous avons trouvé des ambiguïtés dans l'utilisation de ces termes, ainsi que des non-spécificités ou des chevauchements dans ces nominations et dans les connotations et classifications qui les sous-tendent. Certaines des divergences constatées sont celles qui tendent à confondre la recherche conceptuelle avec la recherche qualitative, la recherche bibliographique ou documentaire, les études de cas, les monographies ou même loin de s'inscrire dans un certain type de recherche, étendant la confusion aux concepts méthodologiques tels que cadre théorique ou suivi de l'état de l'art.Nous proposons de passer en revue les fondements, les implications et la portée spécifique de ce type particulier de recherche à partir de quelques réflexions épistémologiques et méthodologiques.Este artigo tem como objetivo apoiar o debate sobre a delimitação e o alcance do que em alguns relatórios de pesquisa e na bibliografia existente tem sido denominado como pesquisa teórica ou pesquisa conceitual. Embora vários autores façam referência a esse tipo de pesquisa, encontramos ambigüidades no uso desses termos, bem como não especificidades ou sobreposições nessas nomeações e nas conotações e classificações que as fundamentam. Algumas das divergências encontradas são aquelas que tendem a confundir pesquisa conceitual com pesquisa qualitativa, pesquisa bibliográfica ou documental, estudos de caso, monografias ou mesmo longe de estarem enquadradas em um determinado tipo depesquisa, estendendo a confusão a conceitos metodológicos como referencial teórico ou acompanhamento do estado da arte.Propomo-nos a fazer uma revisão dos fundamentos, implicações e alcance específico deste tipo particular de investigação a partir de algumas reflexões epistemológicas e metodológicasEl presente artículo pretende abonar el debate sobre la delimitación y alcance de lo que en algunos informes de investigación y en la bibliografía existente se ha nominado como investigación teórica o investigación conceptual. Aunque varios autores hacen referencia a este tipo de investigaciones hemos encontrado ambigüedades en el uso de estos términos, así como inespecificidades o superposiciones en estas nominaciones y en las connotaciones y clasificaciones que les subyacen. Algunas de las divergencias relevadas son las que tienden a confundir la investigación conceptual con la investigación cualitativa, la investigación bibliográfica o documental, el estudio de caso, las monografías o incluso lejos de encuadrarse en un cierto tipo de investigación, hacer extensiva la confusión a conceptos metodológicos tales como marco teórico o rastreo del estado del arte.Proponemosrevisar los fundamentos, implicancias y alcances específicos de este tipo particular de investigaciones a partir de algunas reflexiones epistemológicas y metodológicas

Short-term oleoyl-estrone treatment affects capacity to manage lipids in rat adipose tissue

Background: Short-term OE (oleoyl-estrone) treatment causes significant decreases in rat weight mainly due to adipose tissue loss. The aim of this work was to determine if OE treatment affects the expression of genes that regulate lipid metabolism in white adipose tissue. Results: Gene expression in adipose tissue from female treated rats (48 hours) was analysed by hybridization to cDNA arrays and levels of specific mRNAs were determined by real-time PCR. Treatment with OE decreased the expression of 232 genes and up-regulated 75 other genes in mesenteric white adipose tissue. The use of real-time PCR validate that, in mesenteric white adipose tissue, mRNA levels for Lipoprotein Lipase (LPL) were decreased by 52%, those of Fatty Acid Synthase (FAS) by 95%, those of Hormone Sensible Lipase (HSL) by 32%, those of Acetyl CoA Carboxylase (ACC) by 92%, those of Carnitine Palmitoyltransferase 1b (CPT1b) by 45%, and those of Fatty Acid Transport Protein 1 (FATP1) and Adipocyte Fatty Acid Binding Protein (FABP4) by 52% and 49%, respectively. Conversely, Tumour Necrosis Factor (TNF¿) values showed overexpression (198%). Conclusion: Short-term treatment with OE affects adipose tissue capacity to extract fatty acids from lipoproteins and to deal with fatty acid transport and metabolism