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Polymers Feb 2020A very important issue that needs to be solved as simply and correctly as possible is how to establish the thermal performance of phase-changing materials (PCM). The...
A very important issue that needs to be solved as simply and correctly as possible is how to establish the thermal performance of phase-changing materials (PCM). The undertaken researches have analyzed the values of the thermal performances of the PCM taking into account the method of finite elements and the experimental research, respectively, based on a modern measurement system that was designed and implemented. Butyl stearate which has been encapsulated through complex coacervation in polymethyl methacrylate has been used as a PCM. Samples were made containing 10%, 20%, 30% and 40% PCM, respectively, within their structure. The research has established that at both the hot plate and the cold plate interface, the evolution of the temperature over time, established by both the finite element method (FEM) and experimental research, are quite close, and the best results have been obtained for the P30 sample. A very important thing observed during the finite element method (FEM) is that the simulated thermal flow variation extends between 2700-3110W/m being small enough not to influence the temperature measurement at the interface of hot or cold plates. Thus, the use of the FEM or the experimental research method can be applied with good results, provided that the correct initial conditions are used in the finite element method and that the experimental research is performed using the best possible apparatus.
PubMed: 32085434
DOI: 10.3390/polym12020467 -
The Journal of Biological Chemistry Mar 2022Most mammalian phospholipids contain a saturated fatty acid at the sn-1 carbon atom and an unsaturated fatty acid at the sn-2 carbon atom of the glycerol backbone group....
Most mammalian phospholipids contain a saturated fatty acid at the sn-1 carbon atom and an unsaturated fatty acid at the sn-2 carbon atom of the glycerol backbone group. While the sn-2 linked chains undergo extensive remodeling by deacylation and reacylation (Lands cycle), it is not known how the composition of saturated fatty acids is controlled at the sn-1 position. Here, we demonstrate that lysophosphatidylglycerol acyltransferase 1 (LPGAT1) is an sn-1 specific acyltransferase that controls the stearate/palmitate ratio of phosphatidylethanolamine (PE) and phosphatidylcholine. Bacterially expressed murine LPGAT1 transferred saturated acyl-CoAs specifically into the sn-1 position of lysophosphatidylethanolamine (LPE) rather than lysophosphatidylglycerol and preferred stearoyl-CoA over palmitoyl-CoA as the substrate. In addition, genetic ablation of LPGAT1 in mice abolished 1-LPE:stearoyl-CoA acyltransferase activity and caused a shift from stearate to palmitate species in PE, dimethyl-PE, and phosphatidylcholine. Lysophosphatidylglycerol acyltransferase 1 KO mice were leaner and had a shorter life span than their littermate controls. Finally, we show that total lipid synthesis was reduced in isolated hepatocytes of LPGAT1 knockout mice. Thus, we conclude that LPGAT1 is an sn-1 specific LPE acyltransferase that controls the stearate/palmitate homeostasis of PE and the metabolites of the PE methylation pathway and that LPGAT1 plays a central role in the regulation of lipid biosynthesis with implications for body fat content and longevity.
Topics: Acyltransferases; Animals; Carbon; Fatty Acids; Mammals; Mice; Mice, Knockout; Palmitates; Phosphatidylcholines; Phosphatidylethanolamines; Stearates
PubMed: 35131264
DOI: 10.1016/j.jbc.2022.101685 -
The Journal of Biological Chemistry Oct 2009The mechanisms of free fatty acid-induced lipoapoptosis are incompletely understood. Here we demonstrate that Mcl-1, an anti-apoptotic member of the Bcl-2 family, was...
The mechanisms of free fatty acid-induced lipoapoptosis are incompletely understood. Here we demonstrate that Mcl-1, an anti-apoptotic member of the Bcl-2 family, was rapidly degraded in hepatocytes in response to palmitate and stearate by a proteasome-dependent pathway. Overexpression of a ubiquitin-resistant Mcl-1 mutant in Huh-7 cells attenuated palmitate-mediated Mcl-1 loss and lipoapoptosis; conversely, short hairpin RNA-targeted knockdown of Mcl-1 sensitized these cells to lipoapoptosis. Palmitate-induced Mcl-1 degradation was attenuated by the novel protein kinase C (PKC) inhibitor rottlerin. Of the two human novel PKC isozymes, PKCdelta and PKC, only activation of PKC was observed by phospho-immunoblot analysis. As compared with Jurkat cells, a smaller PKC polypeptide and mRNA were expressed in hepatocytes consistent with an alternative splice variant. Short hairpin RNA-mediated knockdown of PKC reduced Mcl-1 degradation and lipoapoptosis. Likewise, genetic deletion of Pkc also attenuated Mcl-1 degradation and cytotoxicity by palmitate in primary hepatocytes. During treatment with palmitate, rottlerin inhibited phosphorylation of Mcl-1 at Ser(159), a phosphorylation site previously implicated in Mcl-1 turnover. Consistent with these results, an Mcl-1 S159A mutant was resistant to degradation and improved cell survival during palmitate treatment. Collectively, these results implicate PKC-dependent destabilization of Mcl-1 as a mechanism contributing to hepatocyte lipoapoptosis.
Topics: Animals; Apoptosis; Cell Line, Tumor; Fatty Acids; Hepatocytes; Humans; Jurkat Cells; Mice; Myeloid Cell Leukemia Sequence 1 Protein; Palmitates; Proteasome Endopeptidase Complex; Protein Denaturation; Protein Kinase C; Proto-Oncogene Proteins c-bcl-2; Stearates
PubMed: 19734538
DOI: 10.1074/jbc.M109.039545 -
Open Life Sciences 2021Microplastics (MPs) have been documented in different foodstuffs and beverages, that could affect human health due to their ingestion. Furthermore, seafood contamination...
Microplastics (MPs) have been documented in different foodstuffs and beverages, that could affect human health due to their ingestion. Furthermore, seafood contamination with MPs puts pillars of food availability and utilization at risk. The present study investigates MPs and toxic elements pollution in commercially canned fishes from Taif governorate markets. Seven different canned fishes' brands were used in the present study from different manufacturer countries and purchased from Taif markets. Tissue samples were digested by 10% of KOH; then, dry filters were analyzed by Fourier-transform infrared spectroscopy to detect MPs. Filtrates were used to detect any potentially toxic elements by inductively coupled plasma. Different MPs were detected in edible tissue, such as canned Tuna contaminated with nylon, 1,2-polybutadiene, and ethylene vinyl alcohol. Sardines contain ethylene vinyl alcohol and poly(vinyl stearate), but Salmon does not have any MPs. Different elements were present in the selected samples in the decreasing order of Al > Se > Zn and traces of As and Sb. Canned fishes were contaminated with MPs and potentially toxic elements. This contamination could be a warning of the potential health risks with the long-term exposure. Therefore, it is recommended to include micro-, meso-, and even nanoplastics in the guidelines of testing food safety management systems.
PubMed: 34485701
DOI: 10.1515/biol-2021-0086 -
Materials (Basel, Switzerland) Aug 2022Applying a concrete surface treatment method (epoxy or primer) can prevent water from penetrating concrete through surface pores. However, if the concrete surface is...
Applying a concrete surface treatment method (epoxy or primer) can prevent water from penetrating concrete through surface pores. However, if the concrete surface is damaged, the subsequent reconstruction can be expensive and time-consuming. Concrete that is resistant to internal and external water has been extensively developed and used to supplement the surface treatment method. Herein, we prepared specimens by mixing cement mortar with fatty-acid-salt-based calcium stearate attached to two natural pozzolanic materials—diatomite and yellow clay. The physical tests measured (1) the air content, (2) flow test, (3) compressive strength, and (4) activity Factor. Durability experiments were performed on (1) the contact angle, (2) chloride ion diffusion coefficient, and (3) water absorption test. The results revealed that the compressive strength of concrete decreased as the calcium stearate content increased. Furthermore, it was confirmed that the contact angle of the test piece using the pozzolanic substance and calcium stearate was twice as high. It was confirmed that the sand test specimen had the highest water absorption rate, and the DT3% had the lowest. (Sand%: 11.8 > OPC: 6.5 > DT3%: 2.4), the chloride diffusion coefficient also showed similar results. (Sand%: 12.5 > OPC: 8.4 > DT1%: 8.8)Due to its unique insolubility, calcium stearate retards hydrate formation when mixed alone and negates compressive strength loss when combined with pozzolanic mixtures rich in SiO2 and Al2O3. Furthermore, the ideal method for producing water-resistant cement mortar is to evenly disperse calcium stearate in the porous powder of cement mortar.
PubMed: 36013898
DOI: 10.3390/ma15165762 -
Experimental Biology and Medicine... Feb 2021To determine if meconium fatty acid ethyl esters (FAEE) in rat pups is a good biomarker of prenatal exposure and effect to alcohol, three groups of pregnant rats were...
To determine if meconium fatty acid ethyl esters (FAEE) in rat pups is a good biomarker of prenatal exposure and effect to alcohol, three groups of pregnant rats were studied: one control (pair fed) and two treatment groups given 25% alcohol at 2.2 or 5.5 g kg d. The pups were delivered on day 20 and, for each dam, were separated into a male and female group. The body, brain, intestines, and placenta of the pups were obtained, weighed, and stored at -20°C. The pups' intestines (as surrogate of meconium) from each group were pooled, and meconium was analyzed by gas chromatography/mass spectroscopy for FAEE. The meconium showed the following FAEE: ethyl palmitate, ethyl stearate, and ethyl linolenate and were only found in the alcohol-treated group and with high specificity but low sensitivity. Mean body weight of the pups was lower in the treatment groups compared to the control groups. Ethyl palmitate concentration correlated negatively to the pups' mean body and brain weights. Therefore, ethyl palmitate, stearate, and linolenate, in meconium of rat pups prenatally exposed to alcohol, are useful biomarkers of prenatal alcohol exposure, with ethyl palmitate a good biomarker of adverse effect on the pups' body and brain weight.
Topics: Animals; Biomarkers; Body Weight; Brain; Esters; Fatty Acids; Female; Fetal Alcohol Spectrum Disorders; Male; Meconium; Organ Size; Placenta; Predictive Value of Tests; Pregnancy; Prenatal Exposure Delayed Effects; Rats, Sprague-Dawley; Sensitivity and Specificity; Rats
PubMed: 33210553
DOI: 10.1177/1535370220971562 -
Molecules (Basel, Switzerland) Dec 2019Firstly, metformin and repaglinide were degraded under high temperature/humidity, UV/VIS light, in different pH and oxidative conditions. Secondly, a new validated LC-UV...
Firstly, metformin and repaglinide were degraded under high temperature/humidity, UV/VIS light, in different pH and oxidative conditions. Secondly, a new validated LC-UV method was examined, as to whether it validly determined these drugs in the presence of their degradation products and whether it is suitable for estimating degradation kinetics. Finally, the respective LC-MS method was used to identify the degradation products. In addition, using FT-IR method, the stability of metformin and repaglinide was scrutinized in the presence of polyvinylpyrrolidone (PVP), mannitol, magnesium stearate, and lactose. Significant degradation of metformin, following the first order kinetics, was observed in alkaline medium. In the case of repaglinide, the most significant and quickest degradation, following the first order kinetics, was observed in acidic and oxidative media (0.1 M HCl and 3% HO). Two new degradation products of metformin and nine new degradation products of repaglinide were detected and identified when the stressed samples were examined by our LC-MS method. What is more, the presence of PVP, mannitol, and magnesium stearate proved to affect the stability of metformin, while repaglinide stability was affected in the presence of PVP and magnesium stearate.
Topics: Administration, Oral; Carbamates; Chromatography, Liquid; Drug Stability; Excipients; Hypoglycemic Agents; Kinetics; Mass Spectrometry; Metformin; Piperidines; Reproducibility of Results; Solutions; Spectroscopy, Fourier Transform Infrared; Ultraviolet Rays
PubMed: 31817112
DOI: 10.3390/molecules24244430 -
Anesthesiology Sep 2008A newly developed microemulsion propofol consisted of 10% purified poloxamer 188 and 0.7% polyethylene glycol 660 hydroxystearate. The authors studied the...
BACKGROUND
A newly developed microemulsion propofol consisted of 10% purified poloxamer 188 and 0.7% polyethylene glycol 660 hydroxystearate. The authors studied the physicochemical properties, aqueous free propofol concentration, and plasma bradykinin generation. Pharmacokinetics and pharmacodynamics were also evaluated in rats.
METHODS
The pH, particle size, and osmolarity of microemulsion propofol were measured using a pH meter, particle size analyzer, and cryoscopic osmometer, respectively. The aqueous free propofol and plasma bradykinin were measured by a dialysis method and radioimmunoassay, respectively. Microemulsion propofol was administered by zero-order infusion of 0.5, 1.0, and 1.5 mg . kg . min for 20 min in 30 rats. The electroencephalographic approximate entropy was used as a surrogate measure of propofol effect.
RESULTS
The pH, osmolarity, and particle size of microemulsion propofol are 7.5, 280 mOsm/l, and 67.0 +/- 28.5 nm, respectively. The aqueous free propofol concentration in microemulsion propofol was 63.3 +/- 1.2 mug/ml. When mixed with human blood, microemulsion propofol did not generate bradykinin in plasma. Although microemulsion propofol had nonlinear pharmacokinetics, a two-compartment model with linear pharmacokinetics best described the time course of the propofol concentration as follows: V1 = 0.143 l/kg, k10 = 0.175 min, k12 = 0.126 min, k21 = 0.043 min. The pharmacodynamic parameters in a sigmoid Emax model were as follows: E0 = 1.18, Emax = 0.636, Ce50 = 1.87 mug/ml, gamma = 1.28, ke0 = 1.02 min.
CONCLUSIONS
Microemulsion propofol produced a high concentration of free propofol in the aqueous phase. For the applied dose range, microemulsion propofol showed nonlinear pharmacokinetics.
Topics: Adult; Anesthetics, Intravenous; Animals; Bradykinin; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Electroencephalography; Emulsions; Female; Humans; Hydrogen-Ion Concentration; Male; Osmolar Concentration; Pain; Pain Measurement; Particle Size; Poloxamer; Polyethylene Glycols; Propofol; Rats; Rats, Sprague-Dawley; Reference Values; Stearates; Surface-Active Agents
PubMed: 18719441
DOI: 10.1097/ALN.0b013e318182a486 -
International Journal of Molecular... Jun 2022One of the indispensable applications of lipases in modification of oils and fats is the possibility to tailor the fatty acid content of triacylglycerols (TAGs), to meet...
One of the indispensable applications of lipases in modification of oils and fats is the possibility to tailor the fatty acid content of triacylglycerols (TAGs), to meet specific requirements from various applications in food, nutrition, and cosmetic industries. Oleic acid (C18:1) and stearic acid (C18:0) are two common long fatty acids in the side chain of triglycerides in plant fats and oils that have similar chemical composition and structures, except for an unsaturated bond between C9 and C10 in oleic acid. Two lipases from (RML) and (ROL) show activity in reactions involving oleate and stearate, and share high sequence and structural identity. In this research, the preference for one of these two similar fatty acid side chains was investigated for the two lipases and was related to the respective enzyme structure. From transesterification reactions with 1:1 (molar ratio) mixed ethyl stearate (ES) and ethyl oleate (EO), both RML and ROL showed a higher activity towards EO than ES, but RML showed around 10% higher preference for ES compared with ROL. In silico results showed that stearate has a less stable interaction with the substrate binding crevice in both RML and ROL and higher tendency to freely move out of the substrate binding region, compared with oleate whose structure is more rigid due to the existence of the double bond. However, Trp88 from RML which is an Ala at the identical position in ROL shows a significant stabilization effect in the substrate interaction in RML, especially with stearate as a ligand.
Topics: Fungal Proteins; Lipase; Molecular Docking Simulation; Oleic Acids; Rhizomucor; Rhizopus oryzae; Sequence Analysis, Protein; Stearates; Structure-Activity Relationship; Substrate Specificity
PubMed: 35806072
DOI: 10.3390/ijms23137072 -
Journal of Oleo Science Apr 2022Sunflower oil oleogels consisting of 3% and 8% polyglycerol stearate (PGSO) were studied as an alternative frying media for onion rings. The physicochemical properties...
Sunflower oil oleogels consisting of 3% and 8% polyglycerol stearate (PGSO) were studied as an alternative frying media for onion rings. The physicochemical properties and thermo-rheological characteristics of oleogels were provided. The sensorial quality and texture profiles of onion rings fried in oleogels were compared with those fried in control sunflower oil. Free fatty acids at the end of 6 h were determined, and decreasing trend was reported in order as PGSO-8, control (sunflower) oil, and PGSO-3. The oxidation induction time for PGSO-8 was significantly lower (1.46 min) than those of the control and PGSO-3 samples following frying. Compared to the control group, the onion ring samples fried in oleogels absorbed approximately 33-37% less oil. It was thought that this reduction would help consumers to less total calorie and weight gain from the fried products. There were no negative effects of oleogel usage on the L* value, aroma, crispness/texture, and overall acceptability scores for the onion ring samples fried in the oleogels.
Topics: Glycerol; Onions; Organic Chemicals; Polymers; Stearates; Sunflower Oil
PubMed: 35296574
DOI: 10.5650/jos.ess21446