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PubMed1977

Fatty acid profiles of phospholipids in rabbit and bovine dental pulp.

The fatty acid profiles of purified phospholipids were similar in dental pulp from rabbit and bovine teeth. The characteristic fatty acid profile of each phospholipid was similar to that found in several other mammalian tissues. The ethanolamine phosphoglycerides had high levels of arachidonic acid and docosapolyenoic acids. Phosphatidylserine and phosphatidic acid contained high amounts of stearic acid and low levels of polyunsaturated fatty acids. Phosphatidylcholine and sphingomyelin contained high amounts of palmitic acid and low levels of C20 and C22 unsaturated fatty acids, and sphingomyelin contained C24 fatty acids. Phosphatidylinositol contained mainly stearic, oleic, and arachidonic acids. The fatty acid compositions of the purified pulp phospholipids are markedly different from those reported for dentin lipids which have been reported to contain little or no arachidonic acid and docosapolyenoic acids. The possible significance of the polyunsaturated fatty acids and phospholipids in tooth formation and maintenance is discussed.

Animals↗
PubMed1983

Role of cholesterol in the capping of surface immunoglobulin receptors on murine lymphocytes.

Previously, we have shown that the capping of surface immunoglobulins on murine lymphocytes can be affected by modulating the lipid environment of the surface membrane with free fatty acids. In the present study, murine lymphocytes were depleted of cholesterol by incubation with phospholipid vesicles. As the cellular cholesterol:phospholipid ratio decreased, the capping of the surface immunoglobulin was seen to decrease. This inhibition of capping could not be reversed by calcium and is not accompanied by changes in either the cytoskeletal element alpha-actinin or cellular ATP levels. Incubation of the cholesterol-depleted cells with cholesterol-containing phospholipid vesicles raised both the cholesterol:phospholipid ratio and capping levels to values close to those of untreated control cells. Remarkably, stearic acid, a saturated fatty acid, could also restore the capping levels in the cholesterol-depleted cells. On the basis of the present data and measurements of the fluorescence polarization of the probe diphenyl hexatriene, we propose a model in which the protein(s) involved in capping is located in a gel-like lipid domain, and that removal of cholesterol makes this domain less gel-like and inhibits capping. Restoration of the gel-like nature of this domain by the addition of either cholesterol or stearic acid enables the protein(s) to function normally.

Actinin↗
PubMed1999

Metabolism of individual fatty acids during infusion of a triacylglycerol emulsion.

The triacylglycerol emulsion Intralipid was infused into six normal subjects to investigate the metabolism of individual fatty acids in subcutaneous adipose tissue and forearm muscle, by measurement of arteriovenous differences. The composition of plasma nonesterified fatty acids changed steadily after passage through adipose tissue and became similar to that of the emulsion, reflecting hydrolysis of the Intralipidtriacylglycerol by lipoprotein lipase, since endogenous lipolysis (hormone-sensitive lipase activity plus lipoprotein lipase hydrolysis of very low density lipoprotein triacylglycerol) was decreased. There was no significant net release of total or individual fatty acids from forearm muscle although there was a tendency for the composition of the fatty acids in forearm venous plasma to change during passage through the tissue to reflect the composition of the emulsion. This may reflect hydrolysis of emulsion particles by lipoprotein lipase situated in capillaries which drain into the forearm vein. The behavior of stearic acid in the plasma nonesterified fatty acid pool was consistently aberrant, with arterialized concentrations considerably higher than predicted from adipose tissue release, both before and during Intralipid infusion. We conclude that there are no significant differences in the metabolism of specific fatty acids, with the exception of stearic acid.

Adipose Tissue↗
PubMed1987

Spin label study of the perturbation effect of the local anaesthetics tetracaine and dibucaine on synaptosomes at pharmacological concentrations.

The method of electron spin resonance spectroscopy of spin probes was used to determine the lowest concentrations of the local anaesthetics dibucaine and tetracaine exerting perturbations on synaptosome membranes. The perturbation depends on the temperature and the membrane depth, as well as on the concentration and the structure of the anaesthetics. Using spin labelled stearic acid at the 5th carbon position a negligible effect of the anaesthetics on the order parameter was found in the membrane both at 1 degree and 22 degrees, within the buffer concentration 0.01-10 mmol/l, but at 37 degrees and concentrations higher than 0.1 mmol/l the disordering effect was significant and of comparable efficiency for dibucaine and tetracaine. Employing stearic acid labelled at the 16th carbon position, disordering of the hydrocarbon core of the membrane caused by tetracaine or dibucaine was detected at 1 degree and 22 degrees, as well as at 37 degrees. The disordering effect occurred at buffer concentrations higher than 0.01 mmol/l for dibucaine, and higher than 0.1 mmol/l for tetracaine. At equal anaesthetic membrane concentrations and at the 16th carbon membrane depth, dibucaine was approximately twice as effective as tetracaine in perturbing synaptosomes. Tetracaine induced nonlamellar phases in the rat brain lipid membrane as detected by 31P NMR spectroscopy. The dynamic and structural perturbation effects of the local anaesthetics was found in that concentration range at which the anaesthetics influence various activities of biological membranes.

Anesthetics, Local↗
PubMed1993

In vitro and in vivo studies on slow release propranolol hydrochloride suppositories. Pharmacokinetic and pharmacodynamic evaluation.

Matrix-based slow release (SR) compressed propranolol HCl (25 mg) suppositories were formulated using PEG 4000 and either stearic acid or bees wax at different concentrations (5, 7.5 and 10%). In vitro studies revealed good slow release characteristics from the suppositories. Their in vivo performances--pharmacokinetics and pharmacodynamics--were evaluated in rabbits. Different pharmacokinetic parameters were determined from the plasma concentration-time profiles using a model-independent computer programme, RAMKIN. The relative bioavailability of propranolol (CAS 525-66-6) from three SR suppositories containing stearic acid, 7.5 and 10% and bees wax, 5%, was 86.4, 87.8, and 83.6% respectively. Pharmacodynamic response (beta-blockade) was assessed by determining the degree of reduction of isoprenaline-induced tachycardia at different time intervals. A minimum concentration of 40-60 ng/ml drug in plasma was maintained during 1-10 h, and there has been a minimum of about 40-50% of beta-blockade during 1-9 h post administration. A good correlation between pharmacokinetic and pharmacodynamic profiles was observed.

Animals↗
PubMed1988

pH-dependent phase transition of chlorpromazine micellar solutions in the physiological range.

The effects of pH and drug concentration on aggregation properties of chlorpromazine-HCl (CPZ) are examined. The critical micelle concentration (cmc) changes from 0.2 mM at pH 7.3 to 2 mM at pH 5.6 as estimated from the stearic acid spin label solubility measurements. For concentrations above the cmc CPZ micelles undergo a concentration-, temperature- and pH-dependent transition leading to phase separation. This phase transition is followed by a sudden increase of light scattering. The phase diagram pH vs. concentration is obtained by observation of the cloud point for concentrations ranging from 0.01 to 10 mM. The intramicellar environment is probed at pH ranging from 5.5 to 8.0 using a stearic acid spin label. The intramicellar compactness increases smoothly with increasing pH suggesting the weakening of polar heads repulsion due to charge decrease. The reported results indicate that pH effects are relevant and should be properly taken into account in the performance and interpretation of experiments with CPZ.

Chlorpromazine↗
PubMedDate not supplied

Effects of idebenone on the composition of brain synaptosomal membranes of rats.

Male and female CFY rats of 21 months of age were treated per os by 50 mg idebenone per kg body weight/day for 5 weeks while the controls received only the solvent. Synaptosomal fractions of the brain cortex were prepared and tested as follows: (1) Labeling by 1,6-diphenyl-1,3,5-hexatriene (DPH) and the fluorescence anisotropy (r) of this label was measured at various optical densities. The average values of r extrapolated to zero optical density were 0.1831 +/- 0.0025 in the control group and 0.1854 +/- 0.0019 in the idebenone-treated animals; the difference is statistically not significant. (2) Labeling with 3 different spin labels (5-NS, N-oxyl-4', 4'-dimethyloxazolidine derivative of stearic acid with the doxyl groups in C-5; 16-NS, the same derivative of stearic acid with the doxyl groups in C-16 position; and MAL-SL, 3-maleimido-2,2,5,5-tetramethyl-1-pyrrolidinyloxy). Routine ESR spectroscopy was applied to characterize the molecular motion of these labels in their microenvironment. These spin labels did not display any significant change in their environment under the influence of idebenone treatment. (3) Protein contents of the samples were measured and samples of synaptosomes containing 3.5 mg protein were dissolved in 1% Na(Dod)SO4 + 1% beta-mercaptoethanol and boiled for 2 min, then elaborated by gel filtration chromatography on a column of sepharose 2B. The elution fluid was collected in separate fractions of 1 ml volume and their protein content was estimated by measuring the absorbance at 280 nm. Distribution histogram of the protein fractions revealed no difference between the placebo- and verum-treated animals. These studies demonstrate that in vivo application of idebenone does not alter the composition of synaptosomal membranes.

Journal Article↗
PubMed1998

Factor VIIa response to a fat-rich meal does not depend on fatty acid composition: a randomized controlled trial.

A fat-rich meal increases activated factor VII (FVIIa), but it is not clear whether this increase depends on the fatty acid composition of the meal. Therefore, we studied the FVIIa response to fat-rich meals with different fatty acid composition in a randomized controlled crossover trial and investigated whether this response is mediated by an increase in serum triglycerides. Elderly women (> 60 years, n=91) received on separate days four different fat-rich breakfasts (50 energy percent [en%] of fat) and a control breakfast (1.5 en% fat; crossover). The fat-rich breakfasts differed in fatty acid composition: one rich in palmitic acid (21.7 g), one in stearic acid (18.6 g), and the other two in linoleic and linolenic acid-one with a ratio 3:1 (12.5/3.9 g) and the other with a ratio of 15:1 (18.8/1.2 g). At 8 AM before the breakfast (fasting) and at 1 and 3 PM, blood samples were taken, in which FVIIa and serum triglycerides were measured. FVIIa response to the fat-rich meals ranged from 11.6 mU/mL (95% confidence interval: 8.3,14.9) on the stearic meal to 15.9 mU/mL (12.0,19.8) on the linoleic/linolenic 15:1 meal at 1 PM and from 14.9 mU/mL (10.6,19.2) to 21.1 mU/mL (16.6,25.6) for the same meals at 3 PM. The responses did not differ between the fat-rich meals. After the control breakfast, FVIIa decreased, with 6.3 mU/mL (3.9,8.7) at 1 PM and 8.7 mU/mL (6.3,11.1) at 3 PM. The triglyceride response was lower after both linoleic/linolenic rich breakfasts compared with the palmitic and stearic breakfast (P<.05) and was not associated with the FVIIa response at any of the blood sampling occasions. The results of this study show that the response of FVIIa to a fat-rich meal is independent of its fatty acid composition and is not mediated by serum triglycerides.

Aged↗
PubMed1975

Biosynthesis of unsaturated fatty acids in cultured minimal deviations hepatoma 7288 C cells.

Minimal Deviation Hepatoma 7288 C cells were cultured in confluent layer with labeled linoleic, alpha-linolenic, eicosa-8,11,14-trienoic and stearic acids. The cells in culture preserved their ability to convert stearic acid to oleic acid. They also synthesized arachidonic acid from linoleic acid or eicosa-8,11,14-trienoic acid. The conversion was very low with linoleic acid and high with eicosatrienoic acid. Eicosapentaenoic acid and other homologs of the alpha-linolenic acid family were synthesized from alpha-linolenic acid. The biosynthetic patterns were the cells was modified by the fatty acid composition of the media.

Carcinoma, Hepatocellular↗
PubMed1965

FURTHER INVESTIGATIONS OF THE INCORPORATION OF (1-14C)ACETATE INTO THE LIPIDS OF THE SILKWORM BOMBYX MORI L.

1. After the injection of sodium [1-(14)C]acetate, the highest incorporation of (14)C into the lipids of the silkworm was observed after 24hr. 2. The specific radioactivity of the palmitic acid fraction was greater and increased more rapidly than that of the stearic acid fraction, which was consistent with the precursor-product relationship to be expected on the basis of current concepts of fatty acid synthesis in vivo. 3. The results indicate the probability of synthesis of lipid components in tissues other than the fat body. 4. Fractionation studies indicate considerable differences in the rate of incorporation of [1-(14)C]acetate into neutral lipids and phospholipids between larvae and pupae as well as among tissues of larvae. 5. The rate of incorporation of [1-(14)C]acetate remains constant throughout pupal development.

Acetates↗
PubMed1976

Photobleaching. A novel fluorescence method for diffusion studies in lipid system.

(1) The fluorescent molecular 12(9-anthroyloxy)-stearic acid dimerises on irradiation with light of 366 nm wavelength. (2) The dimer is nonfluorescent and can be reconverted to the parent compound by irradiation at 254 nm. (3) Kinetic analysis suggests that the dimerisation proceeds by a diffusion-limited second order mechanism in many solvents. (4) Anomalously high rates seen in other systems can be attributed to localised high concentration regions (clusters) of the fluorescent molecule. (5) The analysis has been extended to oriented lipid bilayers and the results suggest that below the gel-liquid crystalline transition temperature the 12(9-anthroyloxy)-stearic acid is excluded by the lipid matrix and forms regions of localised high concentration. (6) In fluid lipid the results suggest an isotropic distribution of the probe. Calculated diffusion coefficients correspond to those found by other techniques.

Diffusion↗
PubMed2004

Inert medication ingredients causing nonadherence due to religious beliefs.

OBJECTIVE: To report 4 cases of medication nonadherence due to presence of inert ingredients forbidden by the patients' religion. CASE SUMMARIES: We describe 4 cases in which religious concerns about prescribed medications' inert components led to discontinuation of these medications. These inert components are gelatin and stearic acid, which might be derived from pork or beef products. In these 4 cases, patients of Muslim, Orthodox Christian, and Seventh Day Adventist faiths, who consider it against their religion to consume pork products, stopped their medications on discovering this possibility. This led to relapse of their illnesses. DISCUSSION: These cases demonstrate that, for some patients, inert medication components that are forbidden by their religion may lead to discontinuation of medications. This could lead to relapse of symptoms and might even lead to hospitalization. Therefore, it is important for prescribers to inform patients of this possibility when treating patients whose religious background might conflict with these inert medication components. CONCLUSIONS: Patients with religion prohibitions against consumption of pork and/or beef products might stop their medications when prescribed those with pork- and beef-derived gelatin and/or stearic acid. Prescribers should discuss this possibility with their patients, perhaps as part of informed consent.

Adult↗
PubMed1989

Synergistic inhibition of DNA synthesis in Ehrlich ascites tumour cells by a combination of unsaturated fatty acids and hyperthermia.

Wide attention has been given to hyperthermia as a new measure for cancer treatment. Clinical trials of hyperthermia, as they possess antitumour activity on some occasions. When cells were incubated with oleic we examine if fatty acids exert a synergistic effect on Ehrlich ascites tumour cells when combined with hyperthermia, as they possess antitumour activity on some occasions. When cells were incubated with oleic acid and linoleic acid (unsaturated fatty acids) at 37 degrees C, the DNA synthesis of cells was significantly inhibited. Palmitic and stearic acids, which are saturated fatty acids, did not suppress DNA synthesis. Hyperthermic treatment without the presence of fatty acids at 42 degrees C for 1 h decreased DNA synthesis to 62% of the control level of 37 degrees C. The combination of an unsaturated fatty acid and hyperthermia synergistically suppressed DNA synthesis. When the cells were incubated in serum-free medium containing 0.1% albumin, unsaturated fatty acids were more effective in inhibiting DNA synthesis. However, saturated fatty acids had little or no effect on DNA synthesis in control or hyperthermia-treated cells. These results indicate that unsaturated fatty acids are useful for enhancing the inhibitory effect of hyperthermia on DNA synthesis, which may increase the in vitro antitumour effects of hyperthermia.

Animals↗
PubMed1988

Changes of membrane fluidity and Na+,K+-ATPase activity during cellular differentiation in the guinea pig epidermis.

The dynamic properties of plasma membrane in epidermal cells were determined by means of electron spin resonance using two kinds of doxyl stearic acid spin labeling agents: 5-DSA and 12-DSA. 5-DSA and 12-DSA are stearic acid analogues with a nitroxide radical ring at the 5th and 12th carbon positions, and these motions reflect molecular motion of lipid bilayer surrounding the hydrophilic region and the hydrophobic region, respectively. Guinea pig epidermal cells were separated into three regions of keratinocytes by Percoll density gradient centrifugation; the upper, middle, and lower epidermal cells. The order parameter S values for 5-DSA and 12-DSA incorporated into the isolated keratinocytes increased, suggesting a decrease in the plasma membrane fluidity, as cells approached the upper epidermal cell layer. The Na+,K+-ATPase activity as a plasma membrane-bound enzyme was determined in each epidermal cell region, and was found to decrease gradually as the cells approached the upper layer. Accordingly, the differentiation of epidermal cells in the keratinization process was found to be associated with a decrease in plasma membrane fluidity and with a decline of Na+,K+-ATPase activity.

Animals↗
PubMed1983

Electron spin resonance studies of the effects of lipids on the environment of proteins in mitochondrial membranes.

The physical state of mitochondrial membranes has been investigated by means of stearic acid spin labels and of a maleimide spin label covalently bound to protein sulfhydryl groups. Stearic acid spin labels 5-NS and 16-NS show that n-butanol enhances the lipid fluidity of mitochondrial membranes in the whole temperature range between 4 and 37 degrees C; the effects in the hydrophobic membrane core, probed by 16-NS, are already apparent at 10 mM butanol. In liposomes formed of mitochondrial phospholipids, a fluidizing effect appears only at much higher concentration. Such results are compatible with the idea that butanol destabilizes lipid-protein interactions. On the other hand, the ratio between weakly and strongly immobilized SH groups probed by maleimide spin label is only slightly affected in the temperature range of 4-37 degrees C by addition of high concentrations of n-butanol, indicating that the environments probed are stable to agents inducing fluidity changes in the lipids. There are, however, indications that the environment probed by maleimide is affected by lipids, since the spin label, when bound to lipid-depleted mitochondria, becomes more immobilized, reconstitution of such lipid-depleted membranes with phospholipids restores the original spectra.

Adenosine Triphosphatases↗
PubMed2005

Influence of surfactant on gas bubble stability.

Gas-bubble stability is achieved either by a reduction in the Laplace pressure or by a reduction in the permeability of the gas-liquid interface. Although insoluble surfactants have been shown definitively in many studies to lower the permeability of the gas-liquid interface and hence increase the resistance to interfacial mass transfer, remarkably little work has been done on the effects of soluble surfactants. An experimental system was developed to measure the effect of the soluble surfactant dodecyl trimethylammonium bromide on the desorption and absorption of carbon dioxide gas through a quiescent planar interface. The desorption experiments conformed to the model of non-steady-state molecular diffusion. The absorption experiments, however, produced an unexpected mass transfer mechanism, with surface renewal, probably because of instability in the density gradient formed by the carbon dioxide. In general, the soluble surfactant produced no measurable reduction in the rate of interfacial mass transfer for desorption or absorption. This finding is consistent with the conclusion of Caskey and Barlage that soluble surfactants produce a significantly lower resistance to interfacial mass transfer than do insoluble surfactants. The dynamic adsorption and desorption of the surfactant molecules at the gas-liquid interface creates short-term vacancies, which presumably permit the unrestricted transfer of the gas molecules through the interface. This surfactant exchange does not occur for insoluble surfactants. Gas bubbles formed in the presence of a high concentration of soluble surfactant were observed to dissolve completely, while those formed in the presence of the insoluble surfactant stearic acid did not dissolve easily, and persisted for very long periods. The interfacial concentration of stearic acid rises during bubble dissolution, as it is insoluble, and must eventually achieve full monolayer coverage and a state of compression, lowering the permeability of the interface. Thus, insoluble surfactants or hydrophobic impurities from solid surfaces may account for increased bubble stability.

Journal Article↗
PubMed1976

Serum lipids and fatty acid composition of serum lecithin in the non-pregnant state in patients with previous cholestasis of pregnancy.

Serum lipids and fatty acid composition of serum lecithin were studied 8-21 months after delivery in 20 non-pregnant women who during their latest pregnancy had presented signs of CP. These women were compared with normal non-pregnant women (n=18) and with patients with cholestasis of pregnancy (CP) (n=28). In the non-pregnant state women with previous cholestasis of pregnancy (CP) showed in serum lecithin a low relative content of palmitic (16:0) and linoleic (18:2) acids and a high portion of stearic acid (18:0). These findings indicate as a basic defect in CP, a reduction in liver lecithin synthesis via pathway I (Kennedy's pathway) in favour of an increased pathway II (Greenberg's pathway). These data further support the hypothesis of increased estrogen activity as an etiological factor in CP. The basic influence by pregnancy on serum lipids and serum lecithin fatty acid composition was the same in women with CP as in women with a normal pregnancy.

Adult↗
PubMed1979

Immunosuppression in experimental African trypanosomiasis. Polyclonal B-cell activation and mitogenicity of trypanosome-derived saturated fatty acids.

Changes in antibody responses in adult mice infected with Trypanosoma congolense and subsequently challenged with unrelated antigens (sheep red blood cells and pneumococcal polysaccharide) were studied. Immune responses were significantly depressed within 1 week of infection, and complete suppression of both IgM and IgG responses to both types of antigen was established 15 days after immunization. Coincidentally with the development of high parasitaemias, background IgM plaque-forming cell responses to sheep red cell antigen significantly increased in non-immunized T. congolense-infected animals. Autolysates of T. congolense and chloroform-soluble extracts of the autolyzed trypanosome were found to be mitogenic in vitro for the spleen cells of normal mice. Fractionation of these extracts by thin-layer chromatography indicated that the mitogenic activity migrated with the free fatty acids. Substitution of the relevant saturated and unsaturated free fatty acids in the autolyzed trypanosome extracts with commercial pure fatty acids in the mouse spleen cultures indicated that the mitogenicity was due to palmitic and stearic acids. It is suggested that the general immunosuppressing effect of trypanosomes may be attributed, at least in part, to the polyclonal activation, and subsequent depletion and/or clonal exhaustion of B-cells as a result of blastogenic stimulus from the parasites. This may operate, at least in part, through the generation of B-cell mitogenic saturated fatty acids.

Animals↗