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At least 1,621 records · Page 90Linked to original sources
PubMed1984

A study of the activity of soft soaps prepared from a homologous series of saturated fatty acids against cells of Escherichia coli NCTC 9001.

Soaps were prepared by direct neutralization of a homologous series of fatty acids with potassium hydroxide, the acids used being lauric, myristic palmitic and stearic acids. The antibacterial activity of these soaps were studied using Escherichia coli as the test organism. From the various phenomena examined it can be concluded that all the soaps used had a measure of antibacterial activity, the order of this activity being myristate, laurate, palmitate, and stearate. The antibacterial activity of both the palmitate and the stearate can only be described as marginal.

Acriflavine↗
PubMed1983

The fatty acid composition of the tissues of streptozotocin-diabetic rats.

The authors studied acute changes in the fatty acid composition of the tissues of streptozotocin-diabetic rats. They found that streptozotocin diabetes led to changes in the total lipids fatty acid spectrum in serum and in tissues (liver, adipose tissue, renal cortex diaphragm). After only 7 days' diabetes there was an increase in the percentual proportion of saturated fatty acids and a decrease in the amount of polyene fatty acids in the serum and in all the above tissue of diabetic animals. Palmitic acid (16:0) participated in the increase in the proportion of saturated fatty acids in all the given tissues, while stearic acid (18:0) played a role in the increase in the renal cortex and the serum. Among the monoene acids, there was a drop in the proportion of palmitoleic acid (16:1) in the adipose tissue and serum and in the amount of oleic acid (18:1) in the renal cortex, liver and muscle. Linoleic acid (18:2) played a role in the decrease in the proportion of polyene acids in all the given tissues and the serum, while arachidonic acid (20:4) was involved in the drop in the renal cortex, liver and muscle. The results show that diabetes leads to changes in the fatty acid composition of the renal cortex and muscle, as well as of the liver and adipose tissue. At present it is not yet clear whether there is an absolute decrease in the proportion of essential fatty acids, or whether diabetes is characterized by an increase in the amount of lipids in both serum and tissues.

Adipose Tissue↗
PubMed2004

Multipoint recognition of basic proteins at a membrane model.

Cell surface recognition achieves high efficiency and specificity because of its polyvalent nature. A biomimetic model has been designed, which consists of a stearic acid monolayer with embedded calixarene tetraphosphonate receptor molecules. This system is able to distinguish between proteins of varying pI at nanomolar concentrations.

Calixarenes↗
PubMed1988

Different metabolic recycling of the lipid components of exogenous sulphatide in human fibroblasts.

Cultured human fibroblasts were fed with two differently labelled sulphatide molecules [one labelled on C-3 of the sphingosine (Sph) moiety [( Sph-3H]sulphatide), the second on C-1 of stearic acid [( stearoyl-14C]sulphatide)], and the intracellular metabolic fate of radioactivity was monitored. Incorporated radioactivity was almost all recovered in the total lipid extract, regardless of the labelling position of the added sulphatide; however, large differences in the level of incorporation occurred among labelled glycosphingolipids. For example, sphingomyelin was present as the major radiolabelled lipid after [Sph-3H]-sulphatide incubation, but was detectable only in trace amounts after [stearoyl-14C]sulphatide administration; in the latter case the radioactivity was located predominantly in glycerophospholipids. From this finding it can be inferred that the free long-chain base (sphingosine) that originates from lysosomal catabolism of sulphatide is mainly, and quite specifically, utilized for sphingomyelin biosynthesis, whereas the ceramide moiety is not; conversely the fatty acid released from ceramide is non-specifically re-utilized for phospholipid biosynthesis.

Carbon Radioisotopes↗
PubMed1992

[Incorporation of an antineoplastic drug aclarubicin into liposomes in relation to the conditions of its encapsulation].

The results of liposome drug encapsulation of aclarubicin (aclacinomycin A), an antitumor antibiotic, are presented. The method of flow detergent dialysis was applied. Conditions providing maximum encapsulation of aclarubicin (the ratio of lipid components and the lipid/detergent ratio), as well as conditions providing stability of liposomal emulsion (the presence of antioxidants, stearic acid and cholesterol) were defined.

Aclarubicin↗
PubMed1992

Fatty acid composition of normal and malignant cells and cytotoxicity of stearic, oleic and sterculic acids in vitro.

The aim of this study was to investigate the hypothesis that saturated fatty acids are differentially cytotoxic to cancer cells. Three studies were undertaken to: (1) measure the toxicities of stearic and oleic acids to normal and malignant cells in vitro, (2) assess if there is any relationship between toxicity and relative fatty acid composition and (3) determine whether the relative fatty acid composition of a cancer cell line could be modified by sterculic acid, an inhibitor of delta-9-desaturase. Stearic (18:0) and oleic (18:1) acids inhibited the colony-forming abilities of five human cancer cell lines and two non-neoplastic cell lines in a dose-dependent fashion. The concentration of oleic acid required to reduce colony formation ability by 50% was 2.5-6.0-fold greater than that of stearic acid. Addition of sterculic acid to a cancer cell line resulted in steady-state levels of stearic acid and increasing percentage of oleic acid.

Carcinoma, Transitional Cell↗
PubMed1977

Zero-order drug delivery system: theory and preliminary testing.

A new approach to zero-order drug delivery that includes geometric factors is described. An experimental device based on the theory was tested by following the release of stearic acid into ethanol. Three separate trials indicated that the solid was released via a zero-order process in a reproducible manner.

Delayed-Action Preparations↗
PubMed2001

Elasticity of vesicles assessed by electron spin resonance, electron microscopy and extrusion measurements.

The composition of vesicles determines the physical state and elasticity of their bilayers. Fatty acid spin labels were incorporated into vesicles, composed of the single chain non-ionic surfactant octaoxyethylenelaurate-ester (PEG-8-L), the sucrose laurate-ester L-595 and cholesterol sulfate (CS) to monitor local dynamic properties of lipid molecules in vesicle bilayers and to study the elasticity of vesicle bilayers. Studies with the spin label probes 5-, 12- and 16-doxyl stearic acid (DSA) indicated that both the order parameter and the rotational correlation times increased when the doxyl group was positioned closer to the headgroup region. These findings indicate that the fluidity of membranes decreased near the headgroup region. Comparing 16-DSA incorporated in vesicle formulations with either 30 or 70 mol% showed no difference in alkyl chain mobility as was reflected by the order parameter. The rotational correlation times, however, showed a slowdown from 0.38 to 0.71 and 1.13 ns when the PEG-8-L molar content was decreased from 100 to 70 and 30 mol% for PEG-8-L:L-595:CS vesicles, respectively. Extrusion measurements indicated an increase in elasticity of vesicle bilayers as the molar content of PEG-8-L was increased from 10 to 90 mol%. Incorporation of cholesterol sulfate stabilizes vesicles and thereby, decreases the elasticity. The increased elasticity correlated excellent with a reduction in the rotational correlation times observed. In conclusion, these results demonstrate that when the molar content of the single chain non-ionic surfactant PEG-8-L in vesicles is increased the elasticity is enhanced and the rotational correlation time is reduced. The enhanced elasticity might contribute to an optimal design of vesicles as drug carriers for transdermal application.

Caprylates↗
PubMed1978

Selective degradation with phospholipases D and C of radioactive isomeric spin-labelled lipids bound to guinea pig liver microsomal membranes.

Membrane-bound lipids of isolated guinea pig liver microsomal membranes were selectively enzymatically labelled with isomeric (5-, 12-, and 16-)doxyl stearic acid. After reisolation, the membranes were degraded with phospholipases D and C under conditions not requiring detergents or organic solvent activators. The degradation of membrane-bound lipids occurred according to the recognized specificity of phospholipases D and C. Temperature-induced changes of degraded membranes containing radioactive spin-labelled isomeric lipids were followed by the electron spin resonance and spectral changes correlated with the lipid composition of membranes. Discontinuities in plots of experimental spectral parameters versus temperature detected in the case of microsomal membranes before and after degradation with phospholipases D and C were attributed to lipid-protein and lipid-lipid interaction(s). On the basis of these and control experiments, discontinuity at around 10-12 degrees C was attributed to the microsomal membrane phosphatidylcholine intrinsic microsomal membrane protein interaction(s), while discontinuities detected at 19-21 degrees C approximately and at 20-30 degrees C approximately were attributed to the phase separation of Ca or Zn salts of membranous phosphatidic acid and to the similar phenomenon involving membrane-bound diglycerides respectively.

Animals↗
PubMed1985

Reduction in the stearic to oleic acid ratio in the circulating red blood cells: a possible tumour marker in solid human neoplasms.

Gas liquid chromatography study of the 18 carbon chain length fatty acids (C18FA) of the human red blood cells (RBCs) was performed on 65 patients with various clinical disorders. It was found that the stearic to oleic acid ratio (SI) of the RBCs was significantly lower (P less than 0.001) in patients with malignant conditions (n = 20, SI = 0.62 +/- 0.16) compared with pathological non-malignant diseases (n = 10, SI = 1.19 +/- 0.2) and the normal control group (n = 35, SI = 1.57 +/- 0.5). Our early results suggest that the increased unsaturation (oleic acid) in the circulating RBCs could be used as a chemical marker in various solid neoplasms.

Chromatography, Gas↗
PubMed1992

Fluorescence quenching of spectrin and other red cell membrane cytoskeletal proteins. Relation to hydrophobic binding sites.

The intrinsic fluorescence of spectrin is strongly quenched by low concentrations of 2-bromostearate. This results from binding at a series of hydrophobic sites. Analysis of dynamic fluorescence quenching by acrylamide, iodide and caesium ions, separately and in conjunction with 2-bromostearate, leads to the conclusion that most of the tryptophan side-chains are exposed to solvent. The sites at which the fatty-acid-quenched tryptophans are located apparently interact with the lipid bilayer in the cell, as judged by quenching by bromostearate dissolved in the lipid phase. A minor proportion of the side-chains in native spectrin give rise to sharp proton magnetic resonance signals, indicative of segmental mobility; these chain elements contain some tryptophan residues, as revealed by weak downfield signals from the heterocyclic ring protons. These signals are not appreciably perturbed by stearic acid or by phosphatidylserine liposomes, suggesting that the hydrophobic binding sites are not in mobile chain elements. By contrast with a series of globular proteins which, with the exception of serum albumins, show little or no quenching by 2-bromostearate, the peripheral red cell membrane skeletal proteins ankyrin (and its spectrin-binding domain), protein 4.1 and (to a lesser extent) actin show evidence of a high affinity for the hydrophobic ligand and may, like spectrin, interact directly with the bilayer in situ.

Binding Sites↗
PubMed2005

[Studies on chemical constituents from rhizome of Impatiens pritzellii var. hupehensis].

OBJECTIVE: To study the chemical constituents from the rhizome of Impatiens pritzellii var. hupehensis. METHOD: The rhizome were extracted with methanol, isolated and purified by column chromatography on silica gel. All the compounds were identified on the basis of spectral analysis (including IR, MS, NMR) and physico-chemical characters. RESULT: Five compounds were identified as a-spinasterol (I), alpha-spinasteryl-7, 22-dien-3-O-beta-D-glucopyranoside (II), stigmast-7, 22-dien-3-one (III), stearic acid (IV), hentriantane (V). CONCLUSION: Compound I is isolated from this plant for the first time, Compound II, III, IV, V are isolated from genus Balsaminaceae for the first time.

Impatiens↗
PubMed1963

Cell guidance by alterations in monomolecular films.

Monolayers of stearic and behenic acids were transferred to quartz slides by the Blodgett technique. Troughs of different depths were cut into these multilayers (substrata), and additional monolayers were superimposed. When cultured and fresh embryonic cells were grown on these substrata, the cells were entrapped within troughs whose depths were as small as 60 angstroms. The results demonstrate cellular responses to molecular changes in contact surfaces.

Cell Biology↗
PubMed1998

Arginine to glutamine substitutions in the fourth module of Xenopus interphotoreceptor retinoid-binding protein.

PURPOSE: Interphotoreceptor retinoid-binding protein (IRBP) is unusual for a lipid-binding protein in that its gene is expressed uniquely by cells of photoreceptor origin and consists of four homologous repeats, each coding for a module of approximately 300 amino acid residues. All-trans retinol binding domains, which appear to be present in each module, are composed of conserved hydrophobic regions [Baer et al, Exp Eye Res 1998; 66:249-262]. Here we investigate the role of highly conserved arginines contained in these regions. METHODS: To study the arginines in an individual module without the interference of ligand-binding activity elsewhere in the protein, we expressed in E. coli the fourth module of Xenopus IRBP by itself as a soluble thioredoxin fusion protein (X4IRBP). Arginines 1005, 1041, 1073 and 1122 were separately replaced by glutamine using PCR overlap extension mutagenesis. The glutamine substitutions were confirmed by liquid chromatography-tandem mass spectrometry. The binding of all-trans retinol and 9-(9-anthroyloxy)stearic acid (9-AS) to X4IRBP and each of the mutants was evaluated by fluorescence spectroscopy. Binding was followed by monitoring the enhancement of ligand fluorescence and the quenching of protein endogenous fluorescence. The ability of the recombinant proteins to protect all-trans retinol from oxidative degradation was evaluated by monitoring absorbance at 325 nm over time. RESULTS: The substitution of Gln for Arg1005 about doubled the amount of ligand necessary to attain saturation and about doubled the level of fluorescence enhancement obtained at saturation for both all-trans retinol and 9-AS. Although there was not a significant change in the Kd, the substitution increased the calculated number of binding sites (N) from approximately 2 to approximately 4 per polypeptide. The other Arg->Gln mutants did not significantly change the Kd or N. None of the mutations compromised the ability of the module to protect all-trans retinol from degradation. CONCLUSIONS: Our data suggest that the function of the conserved arginines in IRBP is fundamentally different from that of other retinoid-binding proteins. These residues do not appear to play a role in defining the specificity of the ligand-binding domain. Rather, Arg1005 appears to play a role in defining the capacity of the domain. Our data suggest that the binding site consists of a single hydrophobic cavity promiscuous for fatty acids and all-trans retinol.

Amino Acid Substitution↗
PubMed1994

Contact dermatitis from the old formula E45 cream.

In the past 4 years, a high incidence (118/362) of positive patch test reactions to E45 cream were noted in 2 patch testing clinics. 18/54 of those patch tested to all the ingredients demonstrated allergies to ingredients. The most frequent was triethanolamine; lanolin allergy occurring in only 1 patient. The remaining reactions may be explained as irritant reactions resulting from triethanolamine stearate (TES) formation within the cream. The irritancy of triethanolamine stearate was demonstrated in patients and controls. Conductivity studies showed that TES arises from the combination of the ingredients triethanolamine and stearic acid. The formulation of E45 cream was being changed at the time of writing, with the removal of triethanolamine from the product.

Chemistry, Pharmaceutical↗
PubMed2005

[The structure and properties of self-assembly complex LB films of silver nanoparticles].

The structure and properties of Ag self-assembly films have attracted much attention in the past decade, which are to a large extent influenced by the structure and properties of the nanoparticles. In the present work, the single-layer and multi-layer complex films of silver nanoparticles and their absorbates were fabricated by using self-assembly technique. The interaction of silver nanoparticle and its absorbate was studied using absorption spectroscopy and surface enhanced Raman scattering spectroscopy.The Raman enhanced properties of silver nanoparticles, and the structure and properties of the complex films were also investigated. The experimental results indicate that the interaction of octodecyl amic (OA) and silver nanoparticle takes place via the NH2 substitute and the active site on Ag, and there might exist photocatalysis under the laser excitation. In addition, the product from otcodecyl amic and stearic acid(SA) has a weak interaction with silver nanoparticle, which mainly takes place as spatial encumbrance in the self-assembly complex film.

Benzene Derivatives↗
PubMed2004

Investigating the structural and dynamic properties of n-doxylstearic acid in magnetically-aligned phospholipid bilayers by X-band EPR spectroscopy.

X-band electron paramagnetic resonance (EPR) spectroscopy has been employed to investigate the dynamic properties of magnetically-aligned phospholipid bilayers (bicelles) based on the molecular order parameters (S(mol)), the hyperfine splitting values and the line shapes of the EPR spectra. For the first time, a series of EPR spectra of n-doxylstearic acid spin-labels (n = 5, 7, 12, and 16) incorporated into Tm3+-doped parallel-aligned, Dy3+-doped perpendicular-aligned, and randomly dispersed 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dihexanoyl-sn-glycero-3-phosphocholine (DMPC/DHPC) bicelles with respect to the direction of the static magnetic field have been investigated as a function of cholesterol content and temperature variation to characterize the orientational aspects along the hydrocarbon acyl chains. Important general observations are that under conditions for which the bicelle is poised in the liquid crystalline phase, the degree of ordering decreases as the nitroxide moiety is transferred toward the end of the stearic acid acyl chains. The addition of cholesterol increases the phase transition temperature and alignment temperature of the DMPC/DHPC phospholipid bilayers and increases the chain order. However, increasing the temperature of the bicelle system decreases the chain order. This report reveals that the dynamic properties of DMPC/DHPC bicelles agree well with other biological and model membrane systems. The results indicate that magnetically-aligned phospholipid bilayers are an excellent model membrane system.

Cyclic N-Oxides↗
PubMed2001

X-ray diffraction study on ordered, disordered and reconstituted intercellular lipid lamellar structure in stratum corneum.

From small angle X-ray diffraction for the stratum corneum of hairless mouse, it was obtained that in the normal stratum corneum, the 1st, 2nd and 3rd order diffraction peaks for the intercellular lipid lamellar structure appear at 13.8, 6.87 and 4.59 nm, respectively and also a broad hump for the 4th order reflection appears as observed by the previous researchers. In the damaged stratum corneum prepared by the treatment of sodium dodecyl sulfate, these small-angle diffraction peaks disappear and only the broad maxima remain around the 1st, 2nd and 3rd order diffraction peaks. These facts indicate that in the normal stratum the lamellar structure is ordered and in the damaged stratum corneum the lamellar structure is disordered. Furthermore, in the reconstituted lamellar structure obtained by immersing into the dilute suspension of the mixture of ceramide 3, cholesterol and stearic acid, the 1st, 2nd and 3rd order diffraction peaks reappear at 13.3, 6.67 and 4.44 nm, respectively. This fact indicates that the reorganization of the ordered lamellar structure takes place by adding the mixture to the damaged stratum corneum.

Animals↗