[en] Surface properties and aggregation behaviour of mixed surfactant systems with varying molar ratios of hexadecyltrimethylammonium bromide (HTAB) and palm-based caprylic acid (OA) were studied in the present work. The critical micelle concentration (CMC), surface excess concentration (Γ_max), minimum area per molecule (A_min), surface pressure at CMC (Π_CMC), zeta potential and particle size were determined using instrumentations (e.g., surface tensiometer and particle sizer). CMC of HTAB-OA mixed surfactant systems was about 30% (0.532 mM) to 50% (0.359 mM) lower than HTAB single surfactant system (0.787 mM), indicating better surfactant adsorption efficiency. Results also showed that increasing the molar ratio of OA favoured the formation of micelles at low concentration; thus, lowering both CMC and surface tension. However, Γmax of mixed surfactant systems lowered with OA molar ratio, indicating the mixed surfactant systems tend to form stable ion pairs in bulk solution rather than orientating at the air-water interface. CMC values obtained via surface tension measurement were double confirmed by ultraviolet-visible (UV-VIS) absorbance measurement using dye solubilisation. The particle size of mixed surfactant aggregates (250 ± 50 nm) was 50 times larger than the one found in HTAB surfactant (5.6 ± 0.3 nm). Equimolar mixed surfactant system displayed highest colloids stability and aggregates populations. The results suggested the existence of strong synergism when two oppositely charged surfactants are mixed. (author)

[en] Highlights: • Olfactory receptor Olfr15 is expressed on the plasma membranes of mouse pancreatic β-cells. • Octanoic acid potentiates glucose-stimulated insulin secretion via Olfr15. • Long-term octanoic acid treatment increases the expression of glucokinase via Olfr15. • Olfr15 expression is decreased and octanoic acid-induced insulin secretion is impaired in islets of diabetic model mice. Olfactory receptors (ORs) are G protein-coupled receptors that mediate olfactory chemosensation, leading to the perception of smell. ORs are expressed in many tissues, but their functions are largely unknown. Here, we show that the olfactory receptor Olfr15 is highly and selectively expressed in both mouse pancreatic β-cells and MIN6 cells. In addition, octanoic acid (OA), a medium-chain fatty acid, potentiates glucose-stimulated insulin secretion (GSIS). The OA-induced enhancement of GSIS was inhibited by Olfr15 knockdown. Treatment with a PLC inhibitor or an Ins(1,4,5)P₃ receptor (IP₃R) antagonist also blocked the OA-induced enhancement of GSIS. These results suggest that OA potentiates GSIS via Olfr15 though the PLC-IP₃ pathway. Furthermore, long-term treatment with OA increased cellular glucose uptake in MIN6 cells by up-regulating the expression of glucokinase (GK). Moreover, this process was blocked by an IP₃R antagonist and a Ca²⁺/calmodulin-dependent protein kinase kinase (CaMKK) inhibitor. Similarly, OA stimulated GK promoter activity, while either Olfr15 or CaMKIV knockdown blocked the stimulatory effect of OA on GK promoter activity. These results suggest that long-term treatment of OA induces GK promoter activity via Olfr15 through the IP₃-CaMKK/CaMKIV pathway. In islets from type 2 diabetic mice, the expression level of Olfr15 and the OA-induced enhancement of GSIS were strongly reduced. Collectively, our results highlight the crucial role of the olfactory receptor Olfr15 in potentiating GSIS in pancreatic β-cells, suggesting that Olfr15 may be an important therapeutic target in type 2 diabetes.

No abstract available

[en] Solvent extraction of Am(III) and Eu(III) was investigated using two hydroxyoctanoic acids including a new 2-hydroxy-2-trifluoromethyl-octanoic acid (L1-CF₃) and two bidentate N-heteroaromatic compounds as extractants. The new lanthanide(III) complexes with bidentate N-heteroaromatic ligands were synthesized and the structures were characterized to eight- or nine-coordinate. Solvent extraction of Am(III) and Eu(III) in 1-octanol/acetic acid buffer solution was performed. The separation factor using L1-CF₃ was about 2. (author)

[en] The acidolysis reaction of terebinth fruit oil with caprylic and palmitic acid has been investigated. The reaction was catalyzed by lipase (Lipozyme IM from Rhizomucormiehei) and carried out in recirculating packed bed reactor. The effects of reaction parameters have been analyzed using response surface methodology. Reaction time (3.5–6.5 h), enzyme load (10–20%), substrate flow rate (4–8 mL·min−1 ) and substrate mole ratios (Terebinth oil : Palmitic acid : Caprylic acid, 1:1.83:1.22–1:3.07:2.05) were evaluated. The optimum reaction conditions were 5.9 h reaction time, 10% enzyme load, 4 mL·min−1 substrate flow rate and 1:3.10:2.07 substrate mole ratio. The structured lipid obtained at these optimum conditions had 52.23% desired triacylglycerols and a lower caloric value than that of terebinth fruit oil. The melting characteristics and microstructure of the structured lipid were similar to those of commercial margarine fat extracts. The results showed that the structured lipid had the highest oxidative stability among the studied fats. (Author)

[en] Biocompatibility studies of the autoxidized and unoxidized unsaturated medium-long chain length (m-lcl) co-poly-3-hydroxyalkanoates (m-lclPHAs) derived from soya oily acids have been reported. Pseudomonas oleovorans was grown on a series of mixtures of octanoic acid (OA) and soya oily acids (Sy) with weight ratios of 20:80, 28:72 and 50:50 in order to obtain unsaturated m-lcl copolyesters coded PHO-Sy-2080, PHO-Sy-2872 and PHO-Sy-5050, respectively. The PHA films were obtained by solvent cast from CHCl₃. They were all originally sticky and waxy except PHO-Sy-5050. Autoxidation of the unsaturated copolyester films was carried out on exposure to air at room temperature in order to obtain crosslinked polymers. They became a highly flexible elastomer after being autoxidized (about 40 days of autoxidation). The in vivo tissue reactions of the autoxidized PHAs were evaluated by subcutaneous implantation in rats. The rats appeared to be healthy throughout the implantation period. No symptom such as necrosis, abscess or tumorigenesis was observed in the vicinity of the implants. Retrieved materials varied in their physical appearance after 6 weeks of implantation. In vivo biocompatibility studies of the medical applications indicated that the microbial copolyesters obtained were all biocompatible and especially the PHOSy series of copolyesters had the highest biocompatibility among them.

[en] Specific conductance of uranyl soaps in dimethylformamide indicates two critical micelle concentrations CMC(I) and CMC(II). The value of CMC(II) decreases with the increase in chain length of the soap, whereas CMC(I) does not vary at all. The results show that the soaps behave as simple electrolyte. The major conductance at infinite dilution (μsub(o)) and dissociation constant (K) of these soaps have been evaluated. (author). 12 refs

[en] tThe viscosity results of uranyl soaps in dimethylformamide have been explained satisfactorily in terms of the equations proposed by Einstein, Vand, Moulik and Jones-Dole. The values of the CMC and molar volume of uranyl soaps calculated from these equations are in close agreement. (author)

[en] The present study was conducted in sandwich-cultured rat hepatocytes to investigate the chemical basis of glutathione (GSH) depletion by valproic acid (VPA) and evaluate the role of GSH depletion in VPA toxicity. Among the synthetic metabolites of VPA investigated, 4-ene-VPA and (E)-2,4-diene-VPA decreased cellular levels of total GSH, but only (E)-2,4-diene-VPA was more effective and more potent than the parent drug. The in situ generated, cytochrome P450-dependent 4-ene-VPA did not contribute to GSH depletion by VPA, as suggested by the experiment with a cytochrome P450 inhibitor, 1-aminobenzotriazole, to decrease the formation of this metabolite. In support of a role for metabolites, alpha-F-VPA and octanoic acid, which do not undergo biotransformation to form a 2,4-diene metabolite, CoA ester, or glucuronide, did not deplete GSH. A time course experiment showed that GSH depletion did not occur prior to the increase in 2',7'-dichlorofluorescein (a marker of oxidative stress), the decrease in [2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium] (WST-1) product formation (a marker of cell viability), or the increase in lactate dehydrogenase (LDH) release (a marker of necrosis) in VPA-treated hepatocytes. In conclusion, the cytochrome P450-mediated 4-ene-VPA pathway does not play a role in the in situ depletion of GSH by VPA, and GSH depletion is not an initiating event in VPA toxicity in sandwich-cultured rat hepatocytes.

[en] To explore the allelopathic effect of caprylic acid on Conyza canadensis, based on the proteomics data of C. canadensis under caprylic acid treatment, the complete cDNA sequence of CcLhca-Z6 gene was cloned by homologous cloning and RACE technology. The expression of CcLhca-Z6 gene was measured by fluorescence quantitative PCR at different time after caprylic acid application. The results showed that the full length of CcLhca-Z6 was 1016 bp (Gene Bank NO. MH512007.1), encoding 266 amino acid residues with a molecular mass of 28.14 kD and theoretical pI of 5.29. Phylogenetic analysis showed that CcLhca-Z6 protein was clustered into a group with Artemisia annua (PWA84283.1), and the CcLhca-Z6 protein had the closest genetic relationship with Artemisia annua (PWA84283.1). RT-qPCR results showed that the treatment with caprylic acid significantly affected the expression of Lhca-z6 gene in the leaves of C. canadensis which showed a trend of first increasing and then descending with time. It was speculated that the CcLhca-Z6 gene may be the key gene in response to caprylic acid stress. This study laid a foundation for further exploring the function mechanism of plant herbicide caprylic acid. (authors)