Cell-based therapeutics for cardiac repair have been extensively used during the last decade. Preclinical studies have demonstrated the effectiveness of adoptively transferred stem cells for ...enhancement of cardiac function. Nevertheless, several cell-based clinical trials have provided largely underwhelming outcomes. A major limitation is the lack of survival in the harsh cardiac milieu as only less than 1% donated cells survive. Recent efforts have focused on enhancing cell-based therapeutics and understanding the biology of stem cells and their response to environmental changes. Stem cell metabolism has recently emerged as a critical determinant of cellular processes and is uniquely adapted to support proliferation, stemness, and commitment. Metabolic signaling pathways are remarkably sensitive to different environmental signals with a profound effect on cell survival after adoptive transfer. Stem cells mainly generate energy through glycolysis while maintaining low oxidative phosphorylation (OxPhos), providing metabolites for biosynthesis of macromolecules. During commitment, there is a shift in cellular metabolism, which alters cell function. Reprogramming stem cell metabolism may represent an attractive strategy to enhance stem cell therapy for cardiac repair. This review summarizes the current literature on how metabolism drives stem cell function and how this knowledge can be applied to improve cell-based therapeutics for cardiac repair.
Nowadays, development of new biobased/biodegradable polymers from biological resources is of great interest from a sustainability standpoint. Polyhydroxybutyrate (PHB) and polylactic acid (PLA) are ...two biopolymers obtained from renewable resources. In this study, the flame-retardant effect of a newly developed flame retardant (FR) based on melamine in a PLA/PHB blend was studied. Several combinations containing this new FR combined with ammonium polyphosphate (APP) and sepiolite were introduced in a PLA/PHB blend. 20 wt% of FR were introduced into a matrix containing 75 wt% PLA and 25 wt% PHB blended with a microcompounder. According to pyrolysis combustion flow calorimeter (PCFC) analyses, all the FR formulations exhibited reduced flammability. The results revealed a considerable decrease in the peak of heat release rate (pHRR) by 33 % in the presence of the new FR while a reduction of about 60 % for combinations with APP and sepiolite. The new FR system significantly enhanced the fire behaviour of PLA/PHB blend. The work presents the first cone calorimeter analyses of PLA/PHB composites. The fire behaviour evolved from thin sample to a thick charring behaviour highlighted by an increase of the residue after cone calorimeter from 0 to 14.7 % with this FR system.
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► High silica MFI zeolites show selective adsorption for p-cresol in solution. ► Adsorption isotherms in aqueous media performed containing BSA, and in vitro (HS). ► Zeolites to be ...applied without direct contact with serum albumin (ultra-filtrate). ► Completion of haemodialysis procedures by zeolite based selective adsorption units.
The removal of uremic toxins by zeolites is investigated in the context of the exploration of alternative methods to blood purification by dialysis. The case of a partially protein bound molecule, p-cresol, is studied here. High silica MFI type zeolites show a selective adsorption for p-cresol without major ion exchange with the cations present under equilibrium conditions in solution. Adsorption isotherms in different media were performed: pure water, artificial blood serum containing bovine serum albumin and human serum (HS obtained from a pool of 50 dialysis patients). p-Cresol elimination levels of 80–85% were obtained under in vitro conditions. However, in HS, p-cresol affinities for the zeolites are generally reduced as compared with pure water due to a partial obstruction of the pore system by adsorption of proteins on the external surface of zeolites particles. These results show that zeolites can be successfully employed as specific adsorbents for uremic toxins but without direct contact with serum albumin, which means only in the ultra-filtrate.
The aim of this study was to evaluate the efficiency of two Tunisian mineral clays to capture chromium(III) and cadmium(II) present in landfills leachate and to understand the corresponding ...mechanisms of sorption. Kinetic studies, adsorption isotherms, particle size distributions as well as zeta potential evolution with adsorbed amount, and pH were studied. The kinetic study revealed that a pseudo-second-order model agrees with the heavy metals adsorption experimental values for both clays. Negative zeta potential was obtained over the entire studied pH range (3–8) and no isoelectric point was found. Adsorption of Cr(III) had a significant effect on the zeta potential which goes from negative values to positive ones, indicating specific adsorption. Upon the addition of Cd(II), the clay surfaces stayed negatively charged whatever the cadmium concentration.
In this work we present a detailed study on the elastic and magnetoelastic contributions for thin films and bulk materials with hexagonal and cubic crystalline structures. In contrast to bulk ...materials, the effective elastic anisotropy for thin films shows a strong dependence on the epitaxial order of the film on the substrate and the stress-free condition of the out-of-plane strain. The contributions of the elastic and magnetoelastic energies in the effective magnetic anisotropy of films with cubic or hexagonal lattice are obtained for certain epitaxial growth directions.
► Elastic and magnetoelastic anisotropies in thin films and bulk materials. ► Bulk materials are free to deform in all directions and thin films are clamped on a substrate. ► Effects of the constraint magneto-mechanics play a role on the magnetic anisotropies.
a- Influence of benzene (PCA) used in wet MA on the powder properties is studied. a- Nature of exothermic peak, linked to benzene presence on the particles wet milled. a- Adsorbed benzene on the ...particles during wet milling is decomposed by annealing. a- IR and TG-MS studies showed that CO2, CO and C are the main fragments obtained. Nanocrystalline Ni3Fe powders were obtained via wet mechanical alloying using benzene as surfactant. The differential scanning calorimetry (DSC) measurements showed the presence of an exothermic peak which does not correspond to any phase transformation or phase formation as was proved by X-ray diffraction measurements. The exothermic peak was observed neither for the dry milled samples nor for the wet milled and subsequently annealed powders at 350A degree C for 4h. The infra-red (IR) spectra registered for the wet milled samples showed a series of vibration bands corresponding to C6H6 and also to a series of fragments resulting from benzene decomposition. The results obtained by IR investigation were confirmed by thermogravimetry and mass spectrometry (TG+MS) investigations. The main fragments resulting from the benzene decomposition on the surface of the nanocrystalline Ni3Fe powders are: CO2, CO and C. The evolution of the particle size distribution versus the milling time has been determined for the wet mechanical milling process of nanocrystalline Ni3Fe powders. The DSC analysis reveals a displacement of the exothermic peak onset towards lower temperatures and an increase of the surface of this peak attributed to the changes in the particles specific surface and to the quantity of benzene added in the milling experiments.
Purpose
Epinephrine is considered the gold standard vasoconstrictor for hypertensive patients, but few studies report felypressin’s effects. The present study aimed to analyze and compare the effects ...of these two vasoconstrictors, injected by the intravenous route, on the arterial pressure of normotensive, hypertensive and atenolol-treated hypertensive rats.
Method
The hypertension model was one-kidney-one-clip (1K1C): the main left renal artery was partially constricted and the right kidney was surgically removed in 45-day-old male Wistar rats. 1K1C hypertensive rats received atenolol (90 mg/kg/day) by gavage for 2 weeks. 28–35 days after hypertension induction, a catheter was inserted into the left carotid artery to record direct blood pressure values. The following parameters were recorded: minimal hypotensive response, maximal hypertensive response, response duration and heart rate.
Results
Epinephrine, but not felypressin, exerted an important hypotensive action; non-treated hypertensive rats showed more pronounced vasodilation. Treated and non-treated rats showed hypertensive responses of the same magnitudes in all groups; 1K1C atenolol rats showed reduced hypertensive responses to both vasoconstrictors. Felypressin’s response duration was longer than that of epinephrine in all groups. Epinephrine increased heart rate while felypressin reduced this parameter only in the normotensive group.
Conclusions
Our results suggest that felypressin has equipotent pressure responses when compared with epinephrine, showing a greater extent of action. Atenolol’s reduction of hypertensive effects surprisingly suggests that atenolol β-blockade may also be important for felypressin’s cardiovascular effect, as is widely known for epinephrine. Our data suggest that felypressin is safe for hypertensive subjects, in particular those receiving atenolol.
Adsorption properties of zeolites were investigated for the removal of
p
-cresol from aqueous solutions at 37 °C within the context of studying alternative methods to dialysis for removing uremic ...toxin from blood. MFI-framework type zeolites with different degrees of hydrophobicity and charge compensating cations were prepared: one pure silica MFI and four alumino-silicate MFIs (Si/Al = 30), with H
+
, Na
+
, K
+
and Mg
2+
as charge compensating cations. Adsorption isotherms and microcalorimetric measurements show a high affinity of
p
-cresol for all MFI type zeolites. The best capacity is obtained for the pure silica MFI, whereas the alumino-silicate samples show a higher affinity in the low concentration range. In the case of pure silica sample, the microscopic adsorption mechanism including the role of confined water is elucidated with the help of NMR, X-ray analysis (including Rietveld refinement) and Monte Carlo simulations. For all samples the high affinity is preserved in physiological serum solution, even in the presence of other toxin molecules such as urea. It is also shown that the compensating cation state of the samples is imposed by the physiological medium.
Cellular replacement in the heart is restricted to postnatal stages with the adult heart largely postmitotic. Studies show that loss of regenerative properties in cardiac cells seems to coincide with ...alterations in metabolism during postnatal development and maturation. Nevertheless, whether changes in cellular metabolism are linked to functional alternations in cardiac cells is not well studied. We report here a novel role for uncoupling protein 2 (UCP2) in regulation of functional properties in cardiac tissue derived stem‐like cells (CTSCs). CTSC were isolated from C57BL/6 mice aged 2 days (nCTSC), 2 month (CTSC), and 2 years old (aCTSC), subjected to bulk‐RNA sequencing that identifies unique transcriptome significantly different between CTSC populations from young and old heart. Moreover, results show that UCP2 is highly expressed in CTSCs from the neonatal heart and is linked to maintenance of glycolysis, proliferation, and survival. With age, UCP2 is reduced shifting energy metabolism to oxidative phosphorylation inversely affecting cellular proliferation and survival in aged CTSCs. Loss of UCP2 in neonatal CTSCs reduces extracellular acidification rate and glycolysis together with reduced cellular proliferation and survival. Mechanistically, UCP2 silencing is linked to significant alteration of mitochondrial genes together with cell cycle and survival signaling pathways as identified by RNA‐sequencing and STRING bioinformatic analysis. Hence, our study shows UCP2‐mediated metabolic profile regulates functional properties of cardiac cells during transition from neonatal to aging cardiac states.
Loss in cardiac regeneration coincides with metabolic alterations. Whether cellular metabolism regulates cardiac cells function from young to old age remains unknown. Here we demonstrate that uncoupling protein 2 (UCP2) promotes increased glycolysis, proliferation, and survival in cardiac tissue derived stem‐like cells in neonatal heart. In aging, UCP2 is reduced increasing oxidative phosphorylation, reducing glycolysis parallel with reduced proliferation and survival.
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