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PubMed2006

Pegylated nanocapsules produced by an organic solvent-free method: Evaluation of their stealth properties.

PURPOSE: To develop from an original process, a novel generation of stealth lipidic nanocapsules in order to improve the lipophilic drug delivery in accessible sites. MATERIALS AND METHODS: Nanocapsules covered by PEG1500 stearate were obtained by a low energy emulsification method. Conductivity measurements and ternary diagram were performed to describe the formulation mechanism. Hemolytic dosage CH50 and pharmacokinetic study in rats have been achieved in order to study the stealth properties of nanocapsules. RESULTS: Transition from an O/W emulsion to a w/O/W emulsion was necessary to produce PEG1500 stearate nanocapsules. Interestingly nanocapsules with a size around 26 nm and a polydispersity index inferior to 0.1 were obtained. The CH50 test has revealed a very weak complement consumption in the presence of such nanocapsules. Moreover, after intravenous injection into rats, PEG1500 stearate nanocapsules exhibited long circulating properties. The experimental data support the concept of steric repulsion of the surface towards proteins, displayed by nanocapsules covered with PEG1500 stearate. These in vivo results were in agreement with the PEG1500 density calculated at the nanocarrier surface. CONCLUSIONS: Injectable drug carriers have been developed. Their long-circulating properties could confer them a strong potential for lipophilic drug targeting.

Algorithms↗
PubMed2005

The fate and intermediary metabolism of stearic acid.

Coming from the Greek for "hard fat," stearic acid represents one of the most abundant FA in the Western diet. Otherwise known as n-octadecanoic acid (18:0), stearate is either obtained in the diet or synthesized by the elongation of palmitate, the principal product of the FA synthase system in animal cells. Stearic acid has been shown to be a very poor substrate for TG synthesis, even as compared with other saturated fats such as myristate and palmitate, and in human studies stearic acid has been shown to generate a lower lipemic response than medium-chain saturated FA. Although it has been proposed that this may be due to less efficient absorption of stearic acid in the gut, such findings have not been consistent. Along with palmitate, stearate is the major substrate for the enzyme stearoyl-CoA desaturase, which catalyzes the conversion of stearate to oleate, the preferred substrate for the synthesis of TG and other complex lipids. In mice, targeted disruption of the stearoyl-CoA desaturase-1 (SCD1) gene results in the generation of a lean mouse that is resistant to diet-induced obesity and insulin resistance. SCD1 also has been shown to be a key target of the anorexigenic hormone leptin, thus underscoring the importance of this enzyme, and consequently the cellular stearate-to-oleate ratio, in lipid metabolism and potentially in the treatment of obesity and related disorders.

Animals↗
PubMed1991

Sexual dimorphism in the preferential secretion of unsaturated lysophosphatidylcholine by rat hepatocytes but no secretion by sheep hepatocytes.

(1) Rat and ovine hepatocytes were incubated in monolayer culture with various fatty acids to determine their effects on the composition of the lysophosphatidylcholine that was secreted. (2) No lysophosphatidylcholine was detected in the medium from the ovine hepatocytes even though these cells were hormonally responsive and they secreted phosphatidylcholine and triacylglycerol in very-low-density lipoprotein. (3) Lysophosphatidylcholine was readily detected in the incubation medium of rat hepatocytes. The predominant fatty acids in this lipid were unsaturated. Stearate and arachidonate contributed 15 and 34%, and 24 and 26% of the total fatty acids when hepatocytes from male and female rats were used, respectively. The relative proportions of stearate and arachidonate in the phosphatidylcholine secreted from the hepatocytes were 20 and 14%, and 28 and 21% for the males and females, respectively. The equivalent values for stearate and arachidonate for phosphatidylcholine in the hepatocytes were 18 and 17% and 33 and 22% for male and female rats. These results provide further indications of sex differences in hepatic phospholipid metabolism and extend this to the secretion of phosphatidylcholine and lysophosphatidylcholine. (4) The addition of 1 mM stearate to the incubation medium did not significantly decrease the proportion of arachidonate in the lysophosphatidylcholine obtained from the hepatocytes of the male rats. However, the relative proportion of arachidonate was decreased in incubations that contained 1 mM oleate or linoleate. (5) The results provide evidence that the preferential secretion of unsaturated lysophosphatidylcholine by the liver may provide a system for transporting unsaturated fatty acids and choline to other organs in non-ruminant animals. However, this mechanism may not operate for ruminants.

Animals↗
PubMed1988

A prospective randomized trial on efficacy of antibiotic prophylaxis in asymptomatic teeth with pulpal necrosis and associated periapical pathosis.

A recent study from a private endodontic practice compared "prophylactic" antibiotic (high-dose, 1-day) regimens of penicillin V and erythromycin (base or stearate) for patients who had asymptomatic teeth with pulpal necrosis and associated periapical radiolucent lesions (PN/PL). A 2.2% flare-up incidence was found, with no statistically significant differences for penicillin (0.0%), base (2.9%), and stearate (3.8%). No hypersensitivity responses occurred, and gastrointestinal side effects were found primarily with the erythromycins (12.4%). To ascertain whether or not similar results would occur with student operators in a dental school clinic population, the current study was undertaken. One-hundred ninety-five patients with quiescent PN/PL were randomly given either penicillin V or erythromycin (base or stearate). A 2.6% flare-up incidence was found, with no statistically significant differences for penicillin (3.1%), base (1.5%), and stearate (3.1%). No hypersensitivity responses occurred, and GI side effects were found primarily with the erythromycins (17.7%). As can be seen, the results were very similar to those of the recent endodontic practice study. Hence, it can be concluded that the results of the previous endodontic practice study were not unique to any one clinician or method. A comparison was also made between the "prophylactic" penicillin group of the current study and the placebo control group of our previous dental school clinic, student operator study (in which the methods, population, and regimen were almost identical to those of the current study). The results showed that the "prophylactic" penicillin group had significant fewer flare-ups and non-flare-up-associated swelling and pain than did the placebo group. In view of these findings and those from studies from the literature in which "prophylactic" antibiotics were not used, it is our opinion that the antibiotic regimens used in the current study should be a component of clinical endodontic therapy for quiescent PN/PL.

Adolescent↗
PubMed2006

A nanoscale study of particle friction in a pharmaceutical system.

Studies of single particle interactions in dry powder inhaler (DPI) formulations using atomic force microscopy (AFM) have recently grown in popularity. Currently, these experiments are all based on measuring particle adhesion forces. We broaden this approach by presenting a novel AFM friction study of single particles in a pharmaceutical system, to examine forces acting parallel to a surface. The sliding friction signal of lactose particles attached to AFM cantilevers was recorded in lateral force (LF) mode over 5 microm x 5 microm areas on five different surfaces chosen to represent both relevant inter-particle and particle-surface interactions. A ranking of friction forces was obtained as follows: glass approximately equal to zanamivir >zanamivir-magnesium stearate (99.5%/0.5%, w/w) blend approximately equal to magnesium stearate approximately equal to PTFE. The addition of magnesium stearate to the zanamivir surface dominated and significantly reduced the friction (Kruskal-Wallis test, P<0.001). AFM images of the contacting asperities of the lactose particles show changes in contact morphology due to two processes. Firstly the asperity wears flat due to abrasion and secondly small magnesium stearate particles transfer onto the asperity. It is proposed that in combination with AFM particle adhesion measurements, this method could be used to screen new formulations and the effectiveness of tertiary components in modifying carrier-drug interactions.

Drug Combinations↗
PubMed1999

Unbound rather than total concentration and saturation rather than unsaturation determine the potency of fatty acids on insulin secretion.

Isolated mouse islets were used to compare the effects of three saturated (myristate, palmitate and stearate) and three unsaturated (oleate, linoleate and linolenate) long-chain fatty acids on insulin secretion. By varying the concentrations of fatty acid (250-1250 micromol/l) and albumin simultaneously or independently, we also investigated whether the insulinotropic effect is determined by the unbound or total concentration of the fatty acids. Only palmitate and stearate slightly increased basal insulin secretion (3 mmol/l glucose). All tested fatty acids potentiated glucose-induced insulin secretion (10-15 mmol/l), and the following rank order of potency was obtained when they were compared at the same total concentrations: palmitate approximately = stearate > myristate > or = oleate > or = linoleate approximately = linolenate. The effect of a given fatty acid varied with the fatty acid to albumin molar ratio, in a way which indicated that the unbound fraction is the important one for the stimulation of beta cells. When the potentiation of insulin secretion was expressed as a function of the unbound concentrations, the following rank order emerged: palmitate > myristate > stearate approximately = oleate > linoleate approximately = linolenate. In conclusion, the acute and direct effects of long-chain fatty acids on insulin secretion are due to their unbound fraction. They are observed only at fatty acid/albumin ratios higher than those normally occurring in plasma. Saturated fatty acids are stronger insulin secretagogues than unsaturated fatty acids. Unbound palmitate is by far the most potent of the six common long-chain fatty acids.

Animals↗
PubMed1995

Magic-angle spinning and solution 13C nuclear magnetic resonance studies of medium- and long-chain cholesteryl esters in model bilayers.

The incorporation of cholesteryl esters (CE) with saturated acyl chains into the lamellar structure of phospholipids was studied by 13C nuclear magnetic resonance (NMR) spectroscopy. The CE (octanoate, palmitate, and stearate) were 13C-enriched in the carboxyl carbon to enhance the signals of the small amounts of bilayer-incorporated CE. Magic-angle spinning (MAS) NMR was used to detect signals in unsonicated multilamellar phosphatidylcholine (PC), and solution NMR was used to detect signals in PC small unilamellar vesicles (SUV). All CE showed a carbonyl peak reflecting localization of the carbonyl at the aqueous interface (Hamilton & Small, 1982). The maximal incorporation decreased with chain length, from 5 mol % for octanoate to 1.4 mol % for stearate in multilayers; the stearate ester had a solubility slightly lower than that of cholesteryl oleate (2 mol %). The maximal incorporation of a specific CE was 1.2-2.0 times higher in SUV than in multilayers. Cholesteryl oleate did not prevent solubilization of cholesteryl stearate in the PC interface. CE in excess of the solubility maximum in multilayer samples was shown to be crystalline at 35 degrees C by MAS NMR; thus, in the bilayer the CE gained considerable mobility compared to its mobility in its pure bulk phase at body temperature. Furthermore, CE with two saturated chains were not distinguishable from esters with an unsaturated chain with respect to mobility and position in the interface. These fundamental interfacial properties assure utilization of CE with common dietary fatty acyl chains.

Carbon Isotopes↗
PubMed2005

Synthesis of high surface area hydroxyapatite nanoparticles by mixed surfactant-mediated approach.

A new surfactant-mediated approach was developed to synthesize hydroxyapatite (HAp) nanoparticles with high surface areas by calcination of their precursors encapsulated with calcium stearate using mixed surfactant-containing reaction mixtures. Acidic aqueous solution of calcium phosphate was mixed with both or either nonaoxyethylene dodecyl ether (C12EO9) and polyoxyethylene(20) sorbitan monostearate (Tween 60) and then was treated with aqueous ammonium at 25 degrees C. The C12EO9-based single surfactant system yielded an aggregate of platy HAp nanoparticles 20-40 nm in size, whereas the Tween 60-based single and mixed systems led to lath-shaped HAp nanoparticles 2-8 nm wide and encapsulated with calcium stearate. On calcination at 500 degrees C, the stearate-encapsulated HAp nanoparticles in the latter two systems were deorganized into high surface area HAp nanoparticles. Particularly, the HAp nanoparticles in the mixed system exhibited a specific surface area as high as 364 m2 g(-1) that is roughly 3 times larger than 160 m2 g(-1) for those in the single system. The significantly high surface area for the former is attributed to much less adhesion of decapsulated HAp nanoparticles, which originated from the particle-separating effect of the C12EO9 molecules adsorbed on the outer surface of the stearate-encapsulated HAp nanoparticles to inhibit their agglomeration or interfacial coordination. The present results demonstrate that the mixed use of two different surfactants as a source of encapsulating and templating agent and a particle-separating agent is specifically effective for the synthesis of high surface area HAp nanoparticles.

Journal Article↗
PubMed1996

Excipient interaction with cetylpyridinium chloride activity in tablet based lozenges.

PURPOSE: The purpose of the investigation was to determine the effect of tablet excipients on the activity of cetylpyridinium chloride (CPC) and the relative interaction between excipients and CPC. METHODS: An analytical assay was developed to evaluate the interaction between CPC and the excipients. In vivo activity was investigated using six volunteers by determining the reduction in colony forming units recoverable from the oropharynx after sucking each proprietary lozenge separately on different days. In vitro determinations investigated the relative antimicrobial activity of aqueous solutions of the lozenges and, the effect of pH and tablet base excipients on that activity against Staphylococcus aureus, Streptococcus pyogenes and Candida albicans. RESULTS: Both in vivo and in vitro results showed that the tablet based lozenges had markedly reduced antimicrobial activities compared with previous results with a candy based lozenge (in vivo and in vitro) or the same concentration of aqueous CPC (in vitro). Magnesium stearate suspensions in CPC 250 micrograms/ml indicated that magnesium stearate adsorbed CPC and at 0.4% lozenge weight and above significantly reduced the antimicrobial activity of CPC 250 micrograms/ml. CONCLUSIONS: The reduced activity of CPC in tablet based lozenges resulted from a decreased availability of CPC in solution due to an adsorption of CPC on magnesium stearate. To avoid this reduction in activity tablet based lozenges containing CPC 250 micrograms/ml, or similar concentrations, plus magnesium stearate should contain not more than 0.3% w/w lozenge weight of the lubricant.

Administration, Oral↗
PubMed2001

Uterotrophic effect of a saturated fatty acid 17-ester of estradiol-17beta administered orally to juvenile rats.

In comparison to estradiol-17beta, the naturally synthesized estradiol-17beta-17-fatty acid esters are potent estrogens when administered subcutaneously. A lipophilic character of estradiol-17-esters could partially protect them from metabolic inactivation. In order to compare their relative estrogenic potency when administered orally, the uterotrophic response to different dosages (0, 2.5, 25, 250 and 2500 nmol/kg BW/day) of estradiol-17beta and estradiol-17beta-17-stearate was assessed in juvenile Sprague-Dawley female rats. Estrogens were administered by oral gavage once a day for 6 days. On the 7th day uterus and vagina were dissected, weighed, and examined microscopically. At 2.5 and 25 nmol/kg BW/day, no difference was detected in the uterus weight compared to control animals which received the vehicle alone (corn oil). At 250 nmol/kg BW/day, the uterotrophic response was maximal in estradiol-17beta-17-stearate-treated animals (x2.40-2.70), whereas it was moderate in estradiol-17beta-treated rats (x1.86) at the same dosage. This differential weight gain effect of estradiol-17beta-17-stearate was correlated with typical microscopic changes in uterus and vagina. The results are in favour of a stronger estrogenic effect of orally given lipoidal estrogens compared to estradiol-17beta. This could be explained by a slower but sustained absorption of estradiol-17beta released from estradiol-17beta-17-stearate by esterases and/or by a facilitated transfer of esters in the lymphatic circulation.

Administration, Oral↗
PubMed2006

Final report on the safety assessment of Triethylene Glycol and PEG-4.

Triethylene Glycol and PEG-4 (polyethylene glycol) are polymers of ethylene oxide alcohol. Triethylene Glycol is a specific three-unit chain, whereas PEG-4 is a polymer with an average of four units, but may contain polymers ranging from two to eight ethylene oxide units. In the same manner, other PEG compounds, e.g., PEG-6, are mixtures and likely contain some Triethylene Glycol and PEG-4. Triethylene Glycol is a fragrance ingredient and viscosity decreasing agent in cosmetic formulations, with a maximum concentration of use of 0.08% in skin-cleansing products. Following oral doses, Triethylene Glycol and its metabolites are excreted primarily in urine, with small amounts released in feces and expired air. With oral LD50 values in rodents from 15 to 22 g/kg, this compound has little acute toxicity. Rats given short term oral doses of 3% in water showed no signs of toxicity, whereas all rats given 10% died by the 12th day of exposure. At levels up to 1 g/m3, rats exposed to aerosolized Triethylene Glycol for 6 h per day for 9 days showed no signs of toxicity. Rats fed a diet containing 4% Triethylene Glycol for 2 years showed no signs of toxicity. There were no treatment-related effects on rats exposed to supersaturated Triethylene Glycol vapor for 13 months nor in rats that consumed 0.533 cc Triethylene Glycol per day in drinking water for 13 months. Triethylene Glycol was not irritating to the skin of rabbits and produced only minimal injury to the eye. In reproductive and developmental toxicity studies in rats and mice, Triethylene Glycol did not produce biologically significant embryotoxicity or teratogenicity. However, some maternal toxicity was seen in dams given 10 ml/kg/day during gestation. Triethylene Glycol was not mutagenic or genotoxic in Ames-type assays, the Chinese hamster ovary mutation assay, and the sister chromatid exchange assays. PEG-4 is a humectant and solvent in cosmetic products, with a maximum concentration of use of 20% in the "other manicuring preparations" product category. This ingredient, with an oral LD50 in rats of 32.77 g/kg, has low acute toxicity. Rats given up to 50,000 ppm PEG-4 in drinking water for 5 days showed no permanent signs of toxicity. Rats given daily oral doses up to 2 g/kg/day of PEG-4 for 33 days showed no signs of toxicity. Undiluted PEG-4 produced only minimal injury to the rabbit eye. PEG-4 was not mutagenic in Ames-type assays, did not induce chromosome aberration in an in vivo bone marrow assay, and was negative for genotoxicity in a dominant lethal assay using rats. Other PEG compounds, which have previously been reviewed by the Cosmetic Ingredient Review (CIR) Expert Panel, e.g., PEG-6, are mixtures that likely include Triethylene Glycol and PEG-4, so these data were also considered. PEG-6 and PEG-8 were not dermal irritants in several rabbit studies. PEG-2 Stearate had a potential for slight irritation in rabbits but was not a sensitizer in guinea pigs. PEG-2 Cocamine was a moderate irritant in rabbits, producing severe erythema. In one dermal study, PEG-2 Cocamine was determined to be corrosive to rabbit skin, causing eschar and necrosis. PEG-6 and PEG-8 caused little to no ocular irritation. PEG-8 was not mutagenic or genotoxic in a Chinese hamster ovary assay, a sister-chromatid exchange assay, and in an unscheduled DNA synthesis assay. In clinical studies on normal skin, PEG-6 and PEG-8 caused mild cases of immediate hypersensitivity; PEG-8 was not a sensitizer; PEG-2 Stearate was not an irritant, a sensitizer, or a photosensitizer; and PEG-6 Stearate was not an irritant or sensitizer. In damaged skin, cases of systemic toxicity and contact dermatitis in burn patients were attributed to a PEG-based topical ointment. The CIR Expert Panel acknowledged the lack of dermal sensitization data for Triethylene Glycol and dermal irritation and sensitization data for PEG-4. That PEG-6, PEG-8, and PEG-2 Stearate were not irritants or sensitizers suggested that Triethylene Glycol and PEG-4 also would not be irritants or sensitizers, and the absence of any reported reactions in the case literature and the professional experience of the Expert Panel further supported the absence of any significant sensitization potential. The need for additional data to demonstrate the safety of PEGs Cocamine was related to the Cocamine moiety and is not relevant here. The Panel reminded formulators of cosmetic products that, as with other PEG compounds, Triethylene Glycol and PEG-4 should not be used on damaged skin because of cases of systemic toxicity and contact dermatitis in burn patients have been attributed to a PEG-based topical ointment. Based on its consideration of the available information, the CIR Expert Panel concluded that Triethylene Glycol and PEG-4 are safe as cosmetic ingredients in the present practices and concentrations of use as described in this safety assessment.

Animals↗
PubMed1999

The effect of formulation on radioiodide thyroid uptake in the hyperthyroid cat.

This investigation was designed to compare in vitro dissolution profiles from sodium iodide capsules with radioiodide thyroid uptake in hyperthyroid cats using sodium iodide capsules prepared with a formulation exhibiting a complete release of radioiodide (I-123) in vitro and a formulation with an incomplete release of radioiodide. In vitro dissolution profiles for I-123 sodium iodide capsules with two different formulations were determined using the USP XXIII dissolution test. The two formulations studied in vitro were sodium phosphate dibasic powder with 1% magnesium stearate and calcium phosphate dibasic powder with 3% magnesium stearate. By 20 min after initiation of the dissolution test, over 95% of the I-123 was released from capsules of sodium phosphate dibasic powder. The capsules of calcium phosphate dibasic powder reached 75% at 65 min, with no further release occurring thereafter. There was a statistically significant difference in the dissolution profiles of the two formulations. The thyroid uptake of I-123 from capsules exhibiting complete release and incomplete release of radioiodide was determined in hyperthyroid cats. At 4 hr, the mean percentage thyroid uptake value for sodium phosphate dibasic powder with 1% magnesium stearate (complete release formulation) was 12.0% compared to 9.4% for calcium phosphate dibasic powder with 3% magnesium stearate (incomplete release formulation); at 24 hr, the values were 34.4% compared to 23.7%. The data suggest that the incomplete dissolution profile observed in vitro may correlate with a reduction in the bioavailability of the radioiodide in vivo. However, using the Wilcoxon signed rank test, statistically significant differences did not occur between the complete release formulation and incomplete release formulation at either 4 hr or 24 hr (p > .05). The results of the in vivo study with five hyperthyroid cats were not conclusive due to the variability in response between individual cats.

Abdomen↗
PubMed2002

Effect of formulation variables on the floating properties of gastric floating drug delivery system.

PURPOSE: To evaluate the contribution of formulation variables on the floating properties of a gastric floating drug delivery system (GFDDS) using a continuous floating monitoring system and statistical experimental design. METHODS: A modified continuous floating monitoring system, which consisted of an electric balance interfacing with a PC, was designed to perform the continuous monitoring of floating kinetics of GFDDS. Several formulation variables, such as different types of hydroxypropyl methylcellulose (HPMC), varying HPMC/Carbopol ratio, and addition of magnesium stearate, were evaluated using Taguchi design, and the effects of these variables were subjected to statistical analysis. RESULTS: The continuous floating monitoring system developed was validated, using capsules with different density, and a good correlation between theoretical and experimental values was obtained (R2 = 0.9998), indicating the validity of the setup. The statistical analysis indicated that magnesium stearate had a significant effect on the floating property of GFDDS (p < 0.05), and addition of magnesium stearate could significantly improve the floating capacity of the GFDDS. It was found that the HPMC of higher viscosity grade generally exhibited a greater floating capacity, but the effect was not statistically significant. For polymers with the same viscosity, i.e., K4M and E4M, the degree of substitution of the function group did not show any significant contribution. A better floating behavior was achieved at higher HPMC/Carbopol ratio. Carbopol appeared to have a negative effect on the floating behavior of GFDDS. CONCLUSIONS: It was concluded that by using a validated continuous floating monitoring system, the effect of formulation variables on the floating property of the delivery system and their ranges could be identified. Incorporation of hydrophobic agents, such as magnesium stearate, could significantly improve the floating capacity of the GFDDS.

Acrylic Resins↗
PubMed2004

Kinetics of LCFA inhibition on acetoclastic methanogenesis, propionate degradation and beta-oxidation.

Kinetics of long-chain fatty acids (LCFAs) inhibition on acetoclastic methanogenesis, propionate degradation and beta-oxidation were studied with granular sludge under mesophilic batch conditions. Mathematical expressions used for reaction rates were as shown below: [formula: see text]. The simulated results revealed that the methane production rates from acetate decreased with an increase in both concentration and the number of double bonds of LCFAs. The concentrations of oleate (C18:1), linoleate (C18:2), palmitate (C16:0), and stearate (C18:0) were 0.54 mM, 0.11 mM 1.62 mM, and 2.58 mM, respectively, at which the methane production rates from acetate dropped 10%, and 3.10 mM, 0.72 mM, 5.71 mM, and 5.37 mM, respectively, at which the rates dropped 50%. The inhibitory effects of LCFAs on propionate degradation showed a similar tendency with acetoclastic methanogenesis; however, were less severe. The concentrations of oleate, linoleate, palmitate, and stearate were 1.02 mM, 0.18 mM, 2.34 mM, and 1.92 mM, respectively, at which the propionate degradation rates dropped 10%, and 4.38 mM, 1.17 mM, 5.88 mM, and 5.18 mM, respectively, at which the rates dropped 50%. The observed maximum beta-oxidation rates of oleate, linoleate, palmitate, and stearate were 0.21 mmol (gVSS)(-1) d(-1), 0.09 mmol (gVSS)(-1) d(-1), 0.12 mmol (gVSS)(-1) d(-1), and 0.08 mmol (gVSS)(-1) d(-1), respectively. The lag-phase times in beta-oxidation were also dependent on LCFA concentrations. The concentrations of oleate, linoleate, palmitate, and stearate, at which the lag-phase times became 5 days, were 5.93 mM, 2.24 mM, 4.02 mM, and 2.81 mM, respectively.

Fatty Acids↗
PubMed1992

Fatty acid composition and fatty acid elongase and stearoyl-CoA desaturase activities in tissues of steers fed high oleate sunflower seed.

The effects of a high oleate sunflower seed diet on tissue composition and on fatty acid elongation and desaturation enzyme activities were investigated. Three Simmental calves were fed a standard corn-based diet (2.6% fat); three others were fed the corn-based diet containing 20% high oleate sunflower seed (10.4% fat). Blood samples and perianal adipose tissue samples were obtained at 7, 90 and 180 d on trial. Samples of liver, longissimus dorsi muscle and intestinal mucosa were obtained at the termination of the experiment (195 d on trial). Plasma oleate was higher (P < 0.05) in the cattle fed the sunflower seed, and oleate, myristate (P < 0.05) and stearate (P < 0.06) were elevated in perianal adipose tissue in response to the greater lipid content of the dietary sunflower seed. Dietary sunflower seed decreased the concentration of stearate (P < 0.05) in liver. The high oleate diet significantly (P < 0.05) increased the activity of stearoyl-CoA desaturase activity in muscle, and numerical increases in desaturase activity were observed in liver, adipose and small intestine samples. Elongase activity was unaffected by diet. Because stearate is the primary fatty acid available for absorption in ruminants, elevated oleate in plasma and depressed stearate in liver of cattle fed sunflower seed may have reflected an adaptive response of stearoyl-CoA desaturase in their tissues.

Acetyltransferases↗
PubMed1997

Liver microsomal membrane fluidity and microsomal desaturase activities in adult spontaneously hypertensive rats.

OBJECTIVE: The purpose of the present study was to investigate liver microsomal membrane fluidity simultaneously with membrane fatty acid composition and desaturase activities in spontaneously hypertensive rats (SHR). DESIGN AND METHODS: The membrane fluidity was determined, after electron spin resonance (ESR) measurement, in SHR compared with normotensive Wistar-Kyoto (WKY) rats, by calculating the order parameter S from ESR spectra of 5-nitroxide stearate and 10-nitroxide stearate, used as spin-labelled fatty acids. Desaturase activities were measured by incubating SHR and WKY rat liver microsomes with [14C]-radiolabeled fatty acids as substrates for desaturation reactions. The fatty acid composition of liver microsomal membranes was determined by gas-liquid chromatography. RESULTS: Whereas no significant difference between S of 5-nitroxide stearate was observed for SHR and WKY rats, S of 10-nitroxide stearate was significantly lower in SHR than it was in WKY rat microsomal membrane, indicating that the core microsomal membrane fluidity was higher in SHR. Significant differences between fatty acid compositions were observed for SHR and WKY rat microsomal membranes. Delta9 and n-6 delta6 microsomal desaturase activities were significantly lower in SHR. CONCLUSION: These results suggest that the higher liver core microsomal membrane fluidity observed in SHR might be dependent on the increased proportion of mono-unsaturated fatty acids. Such observed modifications and the alterations in delta9 and n-6 delta6 desaturase activities suggest that an impaired polyunsaturated fatty acid biosynthesis is related to changes in microsomal membrane fluidity in hypertension.

Animals↗
PubMed1982

Dose-related pharmacokinetics after oral administration of a new formulation of erythromycin base.

1 Erythromycin concentrations in serum and urine were determined in 24 healthy male, fasting subjects after oral administration of 250, 500, or 1000 mg of erythromycin base (250 mg capsules containing enteric-coated pellets). The subjects also received a film-coated erythromycin stearate tablet (equivalent to 500 mg base). 2 The mean +/- s.d. maximal serum erythromycin concentrations were 1.9 +/- 0.8, 3.8 +/- 1.4, 6.5 +/- 2.9 and 2.9 +/- 1.7 mg/l for 250, 500, or 1000 mg base and 500 mg stearate, respectively. The serum peaks usually occurred after 2 h irrespective of dosage form given. 3 The mean +/- s.d. areas under the serum concentration v time curves (AUC0-infinity) were 4.5 +/- 1.7, 11.2 +/- 4.3, 27.2 +/- 10.6 and 7.5 +/- 3.4 mg l -1 . h after 250, 500, or 1000 mg base, and 500 mg stearate, respectively. 4 The urinary recoveries were 5.0, 6.7, 8.6% of the base doses given and 4.4% of the stearate dose given. 5 Dose-dependent excretion of erythromycin occurred. The increase in AUC was larger than multiples of the lowest base dose.

Administration, Oral↗
PubMed1968

Mammary and whole animal metabolism of glucose and fatty acids in fasting lactating goats.

1. Measurements were made of milk yield, mammary blood flow and mammary arteriovenous differences during the measurement of substrate entry rate by the isotope dilution method using [U-(14)C]glucose, acetate, palmitate, stearate or oleate in conscious lactating goats after 24 hr starvation.2. As previously reported, in fasting, milk yield fell to 40 +/- 3.4 (S.E.)%, lactose secretion to 31 +/- 3.4%, milk fat secretion to 81 +/- 6.7% and mammary blood flow fell to 53 +/- 7.5% of the values before fasting. Mammary O(2) uptake was only 45 +/- 5% of the mean value in fed animals and there were marked falls in the uptakes of glucose, acetate and triglycerides, a smaller fall in beta-hydroxybutyrate uptake, and a large increase in free fatty acid uptake.3. Glucose was found to enter the circulation of the fasting animal at 1-1.6 mg/min/kg body wt. (entry rate) and it gave rise to 3-5% of the total CO(2). The udder took up 10.7-16.1 mg/min/kg of tissue and 8-10% of mammary CO(2) was derived from glucose, although only 5-10% was oxidized. Mammary uptake accounted for 35-43% of the total glucose entering the circulation.4. In the whole animal acetate entry rate was 1-1.4 mg/min/kg and 9-10% of total CO(2) was derived from it. The udder used 0.8-2.4 mg/min/kg of tissue and 9-13% of mammary CO(2) was derived from acetate, 46-79% of that taken up being oxidized. Mammary uptake accounted for only 2-6% of the total acetate entry rate. Negligible quantities of isotope were found in milk fatty acids and there was a fall in the proportion of milk fatty acids of chain length up to C(14) which in fed animals are synthesized from acetate and beta-hydroxybutyrate.5. Palmitate, stearate and oleate entered the circulation as free fatty acids at 0.94-6.8 mg/min/kg and 6-9% of total CO(2) was derived from each. The udder took up 3.0-5.7 mg/min/kg of tissue and 4-8% of mammary CO(2) was derived from each acid. In the udder 8 and 5.5% of stearate and oleate were oxidized and 25% of palmitate. Mammary uptake of stearate was 31.5% of the total entry rate, palmitate 1%, and oleate 7.5%. Only long chain milk fatty acids were labelled.6. During fasting the mammary R.Q. was 0.85 +/- 0.045 compared with a value in fed animals of 1.24 +/- 0.02, when the udder is synthesizing fatty acids from acetate. The total mammary uptake of lipid precursors was only 74% of the rate of milk fat secretion and there was an 18% shrinkage in empty udder volume, suggesting the use of endogenous mammary tissue substrates.

Acetates↗