integrating-continuous-renal-replacement-therapy-into-ex-situ

Integrating Continuous Renal Replacement Therapy into <em>Ex-situ</em> Normothermic Liver Machine Perfusion

Ex situ normothermic machine perfusion (NMP) of the liver has emerged as a dynamic preservation strategy, enabling the maintenance of metabolic activity ...

Hospital Universitario La Paz

The hypothalamus is the principal regulator of global energy balance, enclosing additionally essential neuronal centers for glucose-sensing and osmoregulation. Disturbances in these tightly regulated neuronal networks are thought to underlie the development of severe pandemic syndromes, including obesity and diabetes. In this work, we investigate  the response of individual hypothalamic nuclei to the i.p. administration of glucose or vehicle solutions, using two groups of adult male C57BL6/J fasted mice and a combination of non-invasive T -weighted and diffusion-weighted functional magnetic resonance imaging (fMRI) approaches. MRI parameters were assessed in both groups of animals before, during and in a  phase, following the administration of glucose or vehicle solutions. Hypothalamic nuclei depicted different patterns of activation characterized by: (i) generalized glucose-induced increases of neuronal activation and perfusion-markers in the lateral hypothalamus, arcuate and dorsomedial nuclei, (ii) cellular shrinking events and decreases in microvascular blood flow in the dorsomedial, ventromedial and lateral hypothalamus, following the administration of vehicle solutions and (iii) increased neuronal activity markers and decreased microperfusion parameters in the ARC nuclei of vehicle-administered animals. Immunohistochemical studies performed after the  phase confirmed the presence of  immunoreactive neurons in the arcuate nucleus (ARC) from both animal groups, with significantly higher numbers in the glucose-treated animals. Together, our results reveal that fMRI methods are able to detect  diverse patterns of glucose or vehicle-induced effects in the different hypothalamic nuclei.

Systemic Glucose Administration Alters Water Diffusion and Microvascular Blood Flow in Mouse Hypothalamic Nuclei - An fMRI Study.

Knowledge and quantification of the microcirculation are very important for estimating the status of an organ. Real-time contrast-enhanced sonography assesses microvascular tissue perfusion. This technique has been proposed as innocuous; however, data from experimental animals (rats) have shown renal interstitial microhemorrhage after the procedure. Therefore, we developed a porcine model to explore potential renal damage that in situ exposure might cause.

In situ kidney insonation with microbubble contrast agents does not cause renal tissue damage in a porcine model.

Ghrelin is the natural endogenous ligand for growth hormone secretagogue receptors. This peptide regulates energy homeostasis and expenditure and is a potential link between gut absorptive function and growth. We hypothesized that ghrelin may induce a proliferative and antiapoptotic action promoting the recovery of the hypotrophic gut mucosa. Therefore, the aim of the study was to determine the action of exogenous ghrelin following gut mucosal hypotrophia in rats fed an elemental diet. An elemental diet provides readily absorbable simple nutrients and is usually given to patients with absorptive dysfunction. Male Wistar rats (n = 48) were fed the elemental diet for one week to induce mucosal hypotrophy and then treated for another week with systemic ghrelin and pair-fed with either a normoproteic or hyperproteic isocaloric liquid diet. Another group received a standard diet instead of the elemental diet and served as control (normotrophy). The elemental diet induced intestinal hypotrophia characterized by decreased proliferation in the ileum and increased apoptosis in jejunum and ileum. Ghrelin administration restored normal levels of proliferation in the ileum and apoptosis in the jejunum, with partial apoptosis restoration in the ileum. Ghrelin levels in plasma and fundus were increased in all groups, although the highest levels were found in rats treated with exogenous ghrelin. Ghrelin administration has a positive effect in the hypotrophic gut, regulating both proliferation and apoptosis towards a physiological balance counteracting the negative changes induced by an elemental diet in the intestines.

Exogenous ghrelin regulates proliferation and apoptosis in the hypotrophic gut mucosa of the rat.

Benefits of n-3 polyunsaturated fatty acids (PUFAs) against cardiovascular diseases have been reported. Vascular tone regulation is largely mediated by endothelial factors whose release is modulated by sex hormones. Since the incidence of cardiovascular pathologies has been correlated with decreased levels of sex hormones, the aim of this study was to analyze whether a diet supplemented with the specific PUFA docosahexaenoic acid (DHA) could prevent vascular changes induced by an impaired gonadal function. For this purpose, control and orchidectomized rats were fed with a standard diet supplemented with 5% (w/w) sunflower oil or with 3% (w/w) sunflower oil plus 2% (w/w) DHA. The lipid profile, the blood pressure, the production of prostanoids and nitric oxide (NO), and the redox status of biological samples from control and orchidectomized rats, fed control or DHA-supplemented diet, were analyzed. The vasodilator response and the contribution of NO, prostanoids and hyperpolarizing mechanisms were also studied. The results showed that orchidectomy negatively affected the lipid profile, increased the production of prostanoids and reactive oxygen species (ROS), and decreased NO production and the antioxidant capacity, as well as the participation of hyperpolarizing mechanisms in the vasodilator responses. The DHA-supplemented diet of the orchidectomized rats decreased the release of prostanoids and ROS, while increasing NO production and the antioxidant capacity, and it also improved the lipid profile. Additionally, it restored the participation of hyperpolarizing mechanisms by activating potassium. Since the modifications induced by the DHA-supplemented diet were observed in the orchidectomized, but not in the healthy group, DHA seems to exert cardioprotective effects in physiopathological situations in which vascular dysfunction exists.

Effect of Dietary Docosahexaenoic Acid Supplementation on the Participation of Vasodilator Factors in Aorta from Orchidectomized Rats.

Experimental small bowel transplantation (SBT) in rats has been proven to be a useful tool for the study of ischemia-reperfusion and immunological aspects related to solid organ transplantation. However, the model is not completely refined, specialized literature is scarce and complex technical details are typically omitted or confusing. Most studies related to acute rejection (AR) use the orthotopic standard, with small sample sizes due to its high mortality, whereas those studying chronic rejection (CR) use the heterotopic standard, which allows longer term survival but does not exactly reflect the human clinical scenario. Various animal strains have been used, and the type of rejection and the timing of its analysis differ among authors. The double purpose of this study was to develop an improved unusual AR model of SBT using the heterotopic technique, and to elaborate a guide useful to implement experimental models for studying AR. We analyzed the model's technical details and expected difficulties in overcoming the learning curve for such a complex microsurgical model, identifying the potential problem areas and providing a step-by-step protocol and reference guide for future surgeons interested in the topic. We also discuss the historic and more recent options in the literature.

Difficulties, guidelines and review of developing an acute rejection model after rat intestinal transplantation.

In recent years, the number of lung transplantations performed as the last option for many respiratory diseases has grown considerably, both in adults and children. However, the causes for the relatively short survival of lungs compared to other organ transplants still need to be studied. Techniques have improved since the 1950s when experimental lung transplantation began, and the different animal species used now include rodents. The advantage of using these small species is that the surgical model has been expanded and standardized, and different respiratory problems can be studied. In this review we examine the different technical strategies used in experimental transplantation in rats and mice, focusing on surgical techniques and anesthesia and monitoring methods, and highlighting the major contributions of mouse lung transplantation to the field.

Technical Aspects and Benefits of Experimental Mouse Lung Transplantation.

Over the past few decades, the cardiovascular benefits of a high dietary intake of long-chain polyunsaturated fatty acids (PUFAs), like docosahexaenoic acid (DHA), have been extensively studied. However, many of the molecular mechanisms and effects exerted by PUFAs have yet to be well explained. The lack of sex hormones alters vascular tone, and we have described that a DHA-supplemented diet to orchidectomized rats improve vascular function of the aorta. Based on these data and since the mesenteric artery importantly controls the systemic vascular resistance, the objective of this study was to analyze the effect of a DHA-supplemented diet on the mesenteric vascular function from orchidectomized rats. For this purpose mesenteric artery segments obtained from control, orchidectomized or orchidectomized plus DHA-supplemented diet were utilized to analyze: (1) the release of prostanoids, (2) formation of NO and ROS, (3) the vasodilator response to acetylcholine (ACh), as well as the involvement of prostanoids and NO in this response, and (4) the vasoconstrictor response to electrical field stimulation (EFS), analyzing also the effect of exogenous noradrenaline (NA), and the NO donor, sodium nitroprusside (SNP). The results demonstrate beneficial effects of DHA on the vascular function in orchidectomized rats, which include a decrease in the prostanoids release and superoxide formation that were previously augmented by orchidectomy. Additionally, there was an increase in endothelial NO formation and the response to ACh, in which NO involvement and the participation of vasodilator prostanoids were increased. DHA also reversed the decrease in EFS-induced response caused by orchidectomy. All of these findings suggest beneficial effects of DHA on vascular function by reversing the neurogenic response and the endothelial dysfunction caused by orchidectomy.

Docosahexaenoic Acid Supplemented Diet Influences the Orchidectomy-Induced Vascular Dysfunction in Rat Mesenteric Arteries.

Diabetes is one of the major risk factors for peripheral arterial disease. In patients in whom surgery cannot be performed, cell therapy may be an alternative treatment. Since time is crucial for these patients, we propose the use of allogenic mesenchymal cells.

The effects of allogenic stem cells in a murine model of hind limb diabetic ischemic tissue.

 Modified multivisceral transplantation (MMVTx) refers to the use of a graft that includes all abdominal organs except the liver. The use of this type of transplant in children and adults expanded over the last years with good results. However, long-term survival in experimental models has not been reported. Our aim is to describe in detail some technical modifications of MMVTx to obtain long-term survival.

Article	Year
Systemic Glucose Administration Alters Water Diffusion and Microvascular Blood Flow in Mouse Hypothalamic Nuclei - An fMRI Study. Frontiers in neuroscience\| PubMed ID: 31551685	2019
In situ kidney insonation with microbubble contrast agents does not cause renal tissue damage in a porcine model. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine\| PubMed ID: 18946100	2008
Exogenous ghrelin regulates proliferation and apoptosis in the hypotrophic gut mucosa of the rat. Experimental biology and medicine (Maywood, N.J.)\| PubMed ID: 20407078	2010
Effect of Dietary Docosahexaenoic Acid Supplementation on the Participation of Vasodilator Factors in Aorta from Orchidectomized Rats. PloS one\| PubMed ID: 26540339	2015
Difficulties, guidelines and review of developing an acute rejection model after rat intestinal transplantation. Transplant immunology\| PubMed ID: 27102447	2016
Technical Aspects and Benefits of Experimental Mouse Lung Transplantation. Archivos de bronconeumologia\| PubMed ID: 27259359	2016
Docosahexaenoic Acid Supplemented Diet Influences the Orchidectomy-Induced Vascular Dysfunction in Rat Mesenteric Arteries. PloS one\| PubMed ID: 28068359	2017
The effects of allogenic stem cells in a murine model of hind limb diabetic ischemic tissue. PeerJ\| PubMed ID: 28852591	2017
Modified Multivisceral Transplantation with Native Spleen Removal in Rats. European journal of pediatric surgery : official journal of Austrian Association of Pediatric Surgery ... [et al] = Zeitschrift fur Kinderchirurgie\| PubMed ID: 29475213	2019

Carlota Largo

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