Alessandra Crescenzi

The Small Polyphenolic Molecule Kaempferol Increases Cellular Energy Expenditure and Thyroid Hormone Activation

Disturbances in energy homeostasis can result in obesity and other metabolic diseases. Here we report a metabolic pathway present in normal human skeletal muscle myoblasts that is activated by the small polyphenolic molecule kaempferol (KPF). Treatment with KPF leads to an ∼30% increase in skeletal myocyte oxygen consumption. The mechanism involves a several-fold increase in cyclic AMP (cAMP) generation and protein kinase A activation, and the effect of KPF can be mimicked via treatment with dibutyryl cAMP. Microarray and real-time PCR studies identified a set of metabolically relevant genes influenced by KPF including peroxisome proliferator–activated receptor γ coactivator-1α, carnitine palmitoyl transferase-1, mitochondrial transcription factor 1, citrate synthase, and uncoupling protein-3, although KPF itself is not a direct mitochondrial uncoupler. The cAMP-responsive gene for type 2 iodothyronine deiodinase (D2), an intracellular enzyme that activates thyroid hormone (T3) for the nucleus, is approximately threefold upregulated by KPF; furthermore, the activity half-life for D2 is dramatically and selectively increased as well. The net effect is an ∼10-fold stimulation of D2 activity as measured in cell sonicates, with a concurrent increase of ∼2.6-fold in the rate of T3 production, which persists even 24 h after KPF has been removed from the system. The effects of KPF on D2 are independent of sirtuin activation and only weakly reproduced by other small polyphenolic molecules such as quercetin and fisetin. These data document a novel mechanism by which a xenobiotic-activated pathway can regulate metabolically important genes as well as thyroid hormone activation and thus may influence metabolic control in humans.

Hypertension and Exercise Training Differentially Affect Oxytocin and Oxytocin Receptor Expression in the Brain

We have previously shown that exercise training activates nucleus tractus solitarii (NTS) oxytocinergic projections, resulting in blunted exercise tachycardia. The objective of this study was to determine the effects of hypertension and training on oxytocin (OT) and OT receptor expression in the hypothalamic paraventricular nucleus (PVN) and projection areas (dorsal brain stem [DBS]). Male, normotensive, Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats were trained (55% maximal exercise capacity, 3 months) or kept sedentary, and pressure was measured weekly. DBS sections were processed for immunohistochemistry (polyclonal guinea pig anti-OT) or in situ hybridization for OT and OT receptor (35S-oligonucleotide probes). Other groups of rats had brains removed and frozen to isolate the DBS and PVN; samples were processed for OT and OT receptor cDNA reverse transcription–polymerase chain reaction amplification with &bgr;-actin as the housekeeping gene. Training was equally effective in improving running distance in both groups, with pressure reduction only in SHR (−10%, P<0.05). In trained WKY, baseline bradycardia (P<0.05) occurred simultaneously with increased NTS OT immunostaining and mRNA expression (+3.5-fold), without any change in OT receptor mRNA expression. PVN OT mRNA and DBS OT receptor mRNA expressions were significantly lower in SHR versus WKY (−39% and −56%, respectively). Training did not alter DBS OT receptor density in the SHR group but increased OT mRNA in both PVN and DBS areas (+78% and +45%, respectively). Our results show a marked hypertension-induced reduction in OT receptor mRNA expression, not altered by training. In contrast, training increased OT mRNA expression in sedentary and hypertensive rats, which may facilitate training-induced cardiac performance.

Endogenous Angiotensin and Pressure Modulate Brain Angiotensinogen and AT1A mRNA Expression

Abstract—In the coarctation hypertension model, we showed both dissociation of plasma renin activity from cardiovascular-induced effects and the reversal of hypertension-induced responses by losartan. In this study, we investigated the effects of hypertension on the expression of brain renin-angiotensin system components and the simultaneous functional responses and effects of long-term angiotensin II (AT) receptor blockade on these responses. Rats were given vehicle or losartan for 9 days and subjected to subdiaphragmatic aortic constriction or sham surgery after 4 days of treatment. On the fifth postsurgical day, pressure and heart rate were measured in the conscious state; the brain was perfused and removed afterward. Sequential slices of brainstem were hybridized with 35S-oligodeoxynucleotide probes for angiotensinogen, AT1A, and AT1B receptors and processed for autoradiography and densitometry. In vehicle-treated rats, hypertension was accompanied by tachycardia and marked increments in angiotensinogen and AT1A mRNA expression in the cardiovascular system–controlling brainstem areas. In the nucleus tractus solitarii, AT1A density was correlated with both pressure and heart rate values (P <0.01), whereas angiotensinogen levels were correlated with pressure only (P <0.05). Losartan did not change the pressure of hypertensive rats (142±4 versus 146±2 mm Hg, losartan versus vehicle) and the hypertension-induced angiotensinogen mRNA expression but did block both tachycardic response and hypertension-induced AT1A mRNA expression. Hypertension and losartan did not change AT1B mRNA expression. The hypertension-induced positive feedback on angiotensinogen and AT1A mRNA expression supports the concept of a permissive role for brain angiotensin II in orchestrating circulatory responses during the development of hypertension. These data also explain the efficacy of long-term AT1 receptor blockade to reverse hypertension-induced effects.

Islet transplantation in rodents. Do encapsulated islets really work

CONTEXT Diabetes mellitus type I affects around 240 million people in the world and only in the USA 7.8% of the population. It has been estimated that the costs of its complications account for 5% to 10% of the total healthcare spending around the world. According to World Health Organization, 300 million people are expected to develop diabetes mellitus by the year 2025. The pancreatic islet transplantation is expected to be less invasive than a pancreas transplant, which is currently the most commonly used approach. OBJECTIVES To compare the encapsulated and free islet transplantation in rodents looking at sites of islet implantation, number of injected islets, viability and immunosuppression. METHODS A literature search was conducted using MEDLINE/PUBMED and SCIELO with terms about islet transplantation in the rodent from 2000 to 2010. We found 2,636 articles but only 56 articles from 2000 to 2010 were selected. RESULTS In these 56 articles used, 34% were encapsulated and 66% were nonencapsulated islets. Analyzing both types of islets transplantation, the majority of the encapsulated islets were implanted into the peritoneal cavity and the nonencapsulated islets into the liver, through the portal vein. In addition, the great advantage of the peritoneal cavity as the site of islet transplantation is its blood supply. Both vascular endothelial cells and vascular endothelial growth factor were used to stimulate angiogenesis of the islet grafts, increasing the vascularization rapidly after implantation. It also has been proven that there is influence of the capsules, since the larger the capsule more chances there are of central necrosis. In some articles, the use of immunosuppression demonstrated to increase the life expectancy of the graft. CONCLUSION While significant progress has been made in the islets transplantation field, many obstacles remain to be overcome. Microencapsulation provides a means to transplant islets without immunosuppressive agents and may enable the performance of xenotransplantation. The use of alternative donor sources, fewer islets per capsule and the appropriate deployment location, such as the peritoneal cavity, may give a future perspective to the application of immunoprotective capsules and viability in clinical practice. A variety of strategies, such as genetic engineering, co-encapsulation, improvement in oxygen supply or the establishment of hypoxia resistance will also improve the islet transplantation performance. It remains to be determined which combination of strategies with encapsulation can fulfill the promise of establishing a simple and safe transplantation as a cure for diabetes.

The Impact of the Introduction of MELD on the Dynamics of the Liver Transplantation Waiting List in São Paulo, Brazil

Until July 15, 2006, the time on the waiting list was the main criterion for allocating deceased donor livers in the state of São Paulo, Brazil. After this date, MELD has been the basis for the allocation of deceased donor livers for adult transplantation. Our aim was to compare the waitlist dynamics before MELD (1997–2005) and after MELD (2006–2012) in our state. A retrospective study was conducted including the data from all the liver transplant candidate waiting lists from July 1997 to December 2012. The data were related to the actual number of liver transplantations (Tr), the incidence of new patients on the list (I), and the number of patients who died while being on the waitlist (D) from 1997 to 2005 (the pre-MELD era) and from 2006 to 2012 (the post-MELD era). The number of transplantations from 1997 to 2005 and from 2006 to 2012 increased nonlinearly, with a clear trend to levelling to equilibrium at approximately 350 and 500 cases per year, respectively. The implementation of the MELD score resulted in a shorter waiting time until liver transplantation. Additionally, there was a significant effect on the waitlist dynamics in the first 4 years; however, the curves diverge from there, implying a null long-range effect on the waitlist by the MELD scores.

Trophic effects of adipose derived stem cells on Langerhans islets viability — Review

Langerhans islets transplantation has been proposed to provide an endogenous source of insulin in Type I diabetes. However, the hypoxic stress and the receptors immune reaction suffered by the implants cause them to fail in sustaining the insulin production along the time. Experimental studies have shown that adipose derived stem cells (ADSCs) can secrete cytokines that activate free radical scavengers, antioxidants and chaperone heat/shock proteins leading to reduction of apoptosis in damaged tissues. Therefore, using the PubMed database, we reviewed the experimental studies that investigated the trophic effects of ADSCs on Langerhans islets viability, in vitro and in vivo, from 2009 to 2014. We excluded articles that investigated the effects of other types of mesenchymal stem cells on β-cell survival as well articles that worked in the differentiation of ADSCs into insulin producing cells. The analysis of the experiments revealed that exposure of islets to ADSCs in vitro, even for a short period of time, can enhance islet cell viability and function. In vivo studies also corroborated the trophic effects of ADSCs leading to the improvement of islet function and reduction of the number of the islets required for controlling the receptors glucose levels. This review can contribute to guide future experiments looking for a long term diabetes treatment employing ADSC trophic effects for the enhancement of transplanted Langerhans islet viability and functioning.

Gastric fundus submucosa as a site for islets transplantation: An experimental study

Background Islets of Langerhans transplantation is a promising alternative for glycemic control in patients with type 1 diabetes. The graft site is a factor that has large impact on the functioning of this transplant, and the stomach appears to be a promising location. Our objective is to describe a new experimental model for the grafting of Islets of Langerhans in rat stomachs. Methodology Islets of Langerhans were extracted from 45 isogenic male rats of the Lewis lineage and transplanted into 9 isogenic rats of the Wistar lineage; 5 in the gastric body submucosa, and 4 in the gastric fundus submucosa. Normoglycemia was defined as two successive measurements of <250 mg/dL. No immunosuppression was used. The two groups glycemia control improvement were compared with t-student test. Results The results obtained following the transplantation of the islets in 9 rats showed between 995 and 2310 islets transplanted (mean of 1367). The rats from the gastric submucosa group had a better glycemic level improvement, with a confidence equal to 83.94%. Conclusion Islets graft into the gastric fundus submucosa is a viable model with potential for adequate glycemic control. This model gives potential for new perspectives and future studies in this area.