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PubMed2001

Plasma transport and tissue distribution of beta-carotene, vitamin A and retinol-binding protein in domestic cats.

The objective of this study was to determine retinol, retinyl esters and retinol-binding protein (RBP) as well as carotenoids in plasma, urine, liver and kidneys of randomly selected domestic cats. Retinol (240+/-64 ng/ml, mean+/-S.D.) represented one-third of total retinyl esters (736+/-460 ng/ml) in plasma. Retinyl esters were stearate, palmitate and oleate representing 61+/-6, 36+/-13 and 5+/-3% of total retinyl esters, respectively. In half of the cats, retinyl esters (22+/-21 ng/ml) were found in the urine. Vitamin A in the livers (4317+/-1956 microg/g) was significantly higher than in the kidney cortex and medulla (14.16+/-8.92 and 7.59+/-4.52 microg/g, respectively, both P<0.001). RBP was detected in the plasma but not in the urine. Immunoreactive RBP was observed in hepatocytes and in the cells of the proximal tubules. beta-Carotene was present in plasma but never in tissues. The results show that similar to canines differences in vitamin A metabolism in cats are related to the occurrence of retinyl esters in plasma. They differ, however, with regard to the tissue distribution of beta-carotene and the excretion of vitamin A in the urine.

Animals↗
PubMed1994

Location of M13 coat protein in sodium dodecyl sulfate micelles as determined by NMR.

The major coat protein (gVIIIp) of bacteriophage M13 solubilized in sodium dodecyl sulfate (SDS) detergent micelles was used as a model system to study this protein in the lipid-bound form. In order to probe the position of gVIIIp relative to the SDS micelles, stearate was added, spin-labeled at the 5- or 16-position with a doxyl group containing a stable nitroxide radical. The average position of the spin-labels in the micelles was derived from the line broadening of the resonances in the 13C spectrum of SDS. Subsequently, we derived a model of the relative position of gVIIIp in the SDS micelle from the effect of the spin-labels on the gVIIIp resonances, monitored via 1H-15N HSQC and TOCSY experiments. The results are consistent with the structure of gVIIIp having two helical strands. One strand is a long hydrophobic helix that spans the micelle, and the other is a shorter amphipathic helix on the surface of the micelle. These results are in good agreement with the structure of gVIIIp in membranes proposed by McDonnell et al. on the basis of solid state NMR data [McDonnell, P. A., Shon, K., Kim, Y., & Opella, S. J. (1993) J. Mol. Biol. 233, 447-463]. This study indicates that high-resolution NMR on this membrane protein, solubilized in detergent micelles, is a very suitable technique for mimicking these proteins in their natural environment. Furthermore, the data indicate that the structure of the micelle near the C-terminus of the major coat protein is distorted.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage M13↗
PubMed2006

Sum-frequency spectroscopy analysis of two-component langmuir monolayers and the associated interfacial water structure.

Sum-frequency spectroscopy (SFS) in the CH and OH stretching regions was employed to obtain structural information about Langmuir monolayers on the H(2)O subphase of the model lipid dioctadecyldimethylammonium bromide (DOMA) and of the neutral surfactant methyl stearate (SME) and their mixtures and about the interfacial water structure underneath the films. These results were compared with the sum-frequency spectra of the interface between Langmuir monolayers of stearic acid and stearic acid-DOMA monolayers and water to prove that the uncompensated headgroup charge of DOMA at the interface is the reason for structuring of interfacial water close to the studied monomolecular films. Sum-frequency spectra on D(2)O subphase were also studied to account for the interference between the CH and OH spectral signatures because of the coherent nature of the SFS signals. Interfacial water structure proved to be a determining factor in the behavior of the mixed lipid monolayers. A mixing induced amplification in the surface potential DeltaV observed in our previous work was explained with total increase of the dipole moment for the mixed films, bigger than the arithmetic average for DOMA and SME monolayers alone. The increase is due to the better packing of the molecules in the mixed films and to the decrease in the interfacial water dipole moment arising from a more disordered water structure underneath the mixed monolayers.

Membranes, Artificial↗
PubMed2006

Magnetic Langmuir-Blodgett films of ferritin with different iron contents.

Magnetic Langmuir-Blodgett films of four ferritin derivatives with different iron contents containing 4220, 3062, 2200, and 1200 iron atoms, respectively, have been prepared by using the adsorption properties of a 6/1 mixed monolayer of methyl stearate (SME) and dioctadecyldimethylammonium bromide (DODA). The molecular organization of the mixed SME/DODA monolayer is strongly affected by the presence of the water-soluble protein in the subphase as shown by pi-A isotherms, BAM images, and imaging ellipsometry at the water-air interface. BAM images reveal the heterogeneity of this mixed monolayer at the air-water interface. We propose that the ferritin is located under the mixed matrix in those regions where the reflectivity is higher whereas the dark regions correspond to the matrix. Ellipsometric angle measurements performed in zones of different brightness of the mixed monolayer confirm such a heterogeneous distribution of the protein under the lipid matrix. Transfer of the monolayer onto different substrates allowed the preparation of multilayer LB films of ferritin. Both infrared and UV-vis spectroscopy indicate that ferritin molecules are incorporated within the LB films. AFM measurements show that the heterogeneous distribution of the ferritin at the water-air interface is maintained when it is transferred onto solid substrates. Magnetic measurements show that the superparamagnetic properties of these molecules are preserved. Thus, marked hysteresis loops of magnetization are obtained below 20 K with coercive fields that depend on the number of iron atoms of the ferritin derivative.

Animals↗
PubMed2002

Long-chain fatty acid uptake and oxidation in the perfused liver of Walker-256 tumour-bearing rats.

AIMS/BACKGROUND: The effect of the Walker-256 tumour on uptake and oxidation of long-chain fatty acids was investigated in perfused livers of rats. METHODS: Isolated livers were perfused in a non-recirculating system. Fatty acid uptake, ketogenesis, oxygen uptake and 14CO2-production were measured as well as the activities of the acyl carnitine transferases I and II (CAT I and CAT II). RESULTS: Basal oxygen uptake of livers from tumour-bearing rats was lower. Ketone bodies production derived from the long-chain fatty acids in livers from starved tumour-bearing rats was lower relative to the controls, but 14CO2 production was similar in both groups. The oxygen uptake increment and the mitochondrial NADH/NAD+ redox ratio were also decreased in tumour-bearing rats. The extent of these differences was dependent on the chain length and structure of the fatty acid, the following decreasing sequence of differences between control and tumour-bearing animals being valid: palmitate > oleate > stearate. The CAT I activity of the enzyme isolated from livers of tumour-bearing rats was half that from normal rats when palmitoyl-CoA and oleoyl-CoA were the substrates. CONCLUSIONS: Ketogenesis from exogenous fatty acids is decreased in the livers of Walker-256 tumour-bearing rats in consequence of the diminished activity of the mitochondrial CAT I. The lower rates of oxygen uptake indicate a decreased ATP synthesis, which is consistent with the in vivo lower phosphorylation potential.

Animals↗
PubMed1986

Identification of ecdysone 22-long-chain fatty acyl esters in newly laid eggs of the cattle tick Boophilus microplus.

The five major apolar ecdysone esters present in newly laid eggs of the cattle tick Boophilus microplus have been purified by h.p.l.c. The quantities of the apolar esters present in the eggs were increased by administration of ecdysone to the mature females. G.c.-m.s. analysis, as their methyl esters, of the fatty acids released from the apolar ecdysone derivatives by alkali, coupled with positive-ion fast-atom-bombardment m.s. of the intact ecdysone esters, showed that the compounds consisted of a series of fatty acyl esters of ecdysone. The position of esterification of the ecdysone was established by p.m.r. spectroscopy. The combined data show that the novel apolar derivatives of ecdysone consist of the 22-palmitate, -palmitoleate, -stearate, -oleate, and -linoleate esters respectively. Confirmation was obtained by comparison with synthetic ecdysone 22-palmitate. The significance of the ecdysone fatty acyl esters as a possible source of free hormone during embryogenesis is discussed.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Chemical constituents from Mahkota dewa.

A new phenolic glycoside (1), mahkoside A, together with six known compounds including mangiferin (2), kaempferol-3-O-beta-D-glucoside (3), dodecanoic acid (4), palmitic acid (5) ethyl stearate (6) and sucrose (7), were isolated from the pit of Mahkota dewa. Their structures were identified on the basis of spectroscopic analysis. All the compounds were isolated from the title plant for the first time.

Glucosides↗
PubMedDate not supplied

Fatty Acid ethyl esters in scalp, pubic, axillary, beard and body hair as markers for alcohol misuse.

AIMS: This study examined the possibility of using hair samples other than scalp hair for analysis of fatty acid ethyl esters (FAEE) as markers for alcohol misuse. METHODS: Samples of scalp and pubic hair and, if available, axillary, beard and body hair of one teetotaller, five moderate social drinkers and 22 fatalities were analysed for FAEE by head-space solid-phase microextraction and gas chromatography-mass spectrometry. The sum of the concentrations of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate (C(FAEE)) in the hair samples was compared with information about the drinking behaviour of the individuals. RESULTS: Although there were large differences in the analyte concentrations in hair from different sites in the same individual, cases of chronic excessive alcohol consumption were characterized by C(FAEE) > 1.0 ng/mg in almost all samples. CONCLUSION: FAEE concentrations in hair other than scalp hair can be used as markers of chronic alcohol misuse.

Alcoholism↗
PubMed1977

The properties of tablets containing microcrystalline cellulose.

Tablets have been prepared from mixtures of microcrystalline cellulose (Avicel) and spray dried lactose. Tests on these showed that a maximum value of dissolution rate occurred as the percentage of the cellulose increased. This maximum was at 4% w/w for mixtures containing Avicel PH 101 and coincided with the point of maximum liquid penetration rate. With grade PH 105 this maximum was at 2% w/w and corresponded to the optimum balance between the opposing factors of disintegration and liquid penetration rate. Addition of up to 2% w/w magnesium stearate to the formulation containing 4% w/w PH 101 grade had little effect on pore structure, but decreased the dissolution rate by retarding water penetration. Similar concentrations of Carbowax 4000 caused no such decrease.

Cellulose↗
PubMed1977

The influence of additives on the presentation of a drug in hard gelatin capsules.

The influence of the concentration of lactose, magnesium stearate and sodium lauryl sulphate in the in vitro dissolution and the drug content of hard gelatin capsules filled under conditions which result in a maximum tapped bulk density, has been evaluated by a factorially-designed experiment. The 3 factors have a significant effect on both drug release and capsule filling. Interactions between the 3 factors, however, limit the exact quantification of the magnitude of their influence by a simple linear model. A quadratic relation, when only 2 factors are considered, can be used to provide a prediction of the influence of these factors. The relations between 2 factors are demonstrated as contours of equal in vitro drug release and equal drug content of capsule, at constant concentrations of the third factor. The contours show the important influence of lactose concentration drug release and capsule filling, and the large changes in response which can occur by the addition of a third factor. They also provide a clear guide to the formulation of hard gelatin capsules.

Capsules↗
PubMed1992

Physiochemical interactions of praziquantel, oxamniquine and tablet excipients.

A differential scanning calorimetry and infrared spectrophotometry study of potential interactions between oxamniquine and praziquantel, two synergistic anti-parasitic drugs, indicated that they did not interact on fusion. Mixtures of the two drugs with each of nine common pharmaceutical excipients (Ac-Di-Sol, Avicel, Crospovidone, calcium phosphate, magnesium stearate, starch, lactose, PEG 6000, stearic acid) appeared to interact only with stearic acid. These results suggested that a combination solid dosage form was feasible.

Calorimetry, Differential Scanning↗
PubMed1986

Growth characteristics of selected fungi on polyvinyl chloride film.

The objective of this study was to determine if plasticized polyvinyl chloride film would support the growth of any of nine species of fungi. The film was suspended in distilled water with no nutrients or with glucose or ammonium sulfate. Spores of each of the test species were inoculated into the suspension medium, and the mixture was incubated at 30 degrees C for up to 18 weeks. Most species were found to be capable of utilizing the film for carbon or nitrogen when the other nutrient was supplied. Only two species, Aspergillus fischeri and Paecilomyces sp., were found to be capable of utilizing components of the film without added nutrients. Components of the polyvinyl chloride film were then incorporated into mineral salts medium to determine if these components could serve as carbon sources in the presence of ammonium nitrate. The only component found to be utilized by all the fungi as a carbon source was epoxidized oil, a plasticizer-stabilizer. Calcium-zinc stearate was an available carbon source for all except the Penicillium and Verticillium strains. The only other component utilized was a stearamide, which was metabolized solely by the Aspergillus sp. Only the stearamide contained enough nitrogen to serve as a primary source in the film. The compound, however, did not support growth of fungi in the presence of glucose. It was theorized that either the nitrogen of the stearamide was more readily available to the fungi in the whole film due to the presence of trace nutrients or the nitrogen was supplied by exogenous sources.

Aspergillus↗
PubMed1980

Plasma and salivary concentrations of erythromycin after administration of three different formulations.

In a 6-volunteer cross-over study the pharmacokinetics of 3 erythromycin preparations were compared. A single oral dose of 500 mg of each preparation was administered at each occasion and the levels measured in timed samples of plasma and saliva. Markedly higher blood concentrations of the estolate and propionate were obtained compared to the stearate. Comparison of serum and plasma concentration of the drugs from each split sample showed no significant differences. Plasma concentrations always exceeded those in saliva but for any one preparation a similar ratio was obtained at different times. This may be useful to ascertain compliance and to measure concentration of the compounds where direct measurement in plasma is not practicable.

Adult↗
PubMed1980

Plasma and sputum erythromycin concentrations in chronic bronchitis.

Plasma and sputum concentrations of erythromycin were measured in 10 patients with chronic bronchitis during an eight-day course of a new formulation of erythromycin stearate. The plasma erythromycin levels compared favourably with the minimal inhibitory concentrations for common respiratory pathogens and indicated adequate gastrointestinal absorption when the drug was taken immediately before food. Sputum erythromycin levels were variable and in some patients low or undetectable. Measurable sputum erythromycin levels were approximately 10% of plasma levels with no evidence of accumulation and were of similar order of magnitude to the minimal inhibitory concentrations for common respiratory pathogens except Haemophilus influenzae. There was no correlation between sputum and plasma erythromycin levels. There was a trend for higher erythromycin levels in sputum containing increasing amounts of pus and also when plasma levels increased.

Aged↗
PubMed1975

Phosphatidylethanolamine in liver mitochondria and endoplasmic reticulum: molecular species distribution and turnover.

Phosphatidylethanolamine from mitochondria and microsomes of guinea pig liver was separated by thin-layer chromatography into eight different classes differing in degree of unsaturation. The fatty acid compositions and molar proportions of each class isolated from microsomes were very similar to the corresponding class in mitochondria. In both organelles about half of the total was dienoic species while tetraenes comprised approximately 20%. Stearic acid was the major saturated fatty acid and in each membrane a greater selectivity for stearate over palmitate was found in each sub-class of phosphatidylcholine. Following the intraperitoneal injection of [2 minus-3 H]glycerol, the labelling of each molecular class of phosphatidylethanolamine showed very similar progressions in microsomes and mitochondria over a 3 h interval. In both organelles the highest relative specific activity was attained by penta-plus hexaenoic classes, while the large dienoic class had the lowest relative activity, which, however, increased with time. Analysis of the dienoic class of phosphatidyl-ethanolamine from whole liver showed it to be constituted by a rapidly turning over palmitoyl-linoleoyl fraction and a slowly labelled stearoyl-linoleoyl fraction, a pattern also exhibited by dienoic phosphatidylcholines. The similarities in profile of molecular classes of phosphatidylethanolamine and in the kinetics of labelling in vivo point to a close metabolic relation between the lipids of both organelles, suggestive of a transfer of different molecular classes at comparable rates from the endoplasmic reticulum, the site of synthesis, to the mitochondria. This is consistent with numerous other studies in vitro that have demonstrated inter-organelle exchange of lipids.

Animals↗
PubMed1989

Increased sinusoidal volume and solute extraction during retrograde liver perfusion.

Retrograde isolated liver perfusion has been used to probe acinar functional heterogeneity, but the hemodynamic effects of backward flow have not been characterized. In this study, extraction of a long-chain fatty acid derivative, 12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazol-amino stearate (12-NBDS), was greater during retrograde than during anterograde perfusion of isolated rat liver. To determine whether hemodynamic differences between anterograde and retrograde perfused livers could account for this finding, the hepatic extracellular space was measured for both directions of flow by means of [14C]sucrose washout during perfusion as well as by direct measurement of [14C]sucrose entrapped during perfusion. A three- to fourfold enlargement of the total hepatic extracellular space was found during retrograde perfusion by both approaches. Examination of perfusion-fixed livers by light microscopy and morphometry revealed that marked distension of the sinusoids occurred during retrograde perfusion and that this accounts for the observed increase in the [14C]sucrose space. These findings support the hypothesis that maximum resistance to perfusate flow in the isolated perfused rat liver is located at the presinusoidal level. In addition, increased transit time of perfusate through the liver and greater sinusoidal surface area resulting from sinusoidal distension may account for the higher extraction of 12-NBDS and possibly other compounds by retrograde perfused liver.

4-Chloro-7-nitrobenzofurazan↗
PubMed1990

Vitamin A storage in lungs during perinatal development in the rat.

We examined the ontogeny of vitamin A storage in fetal and neonatal lungs during perinatal development in the rat. High-performance liquid chromatography was used to measure concentrations of vitamin A and its esters, retinyl palmitate and stearate, in various fetal and neonatal tissues at times ranging from gestational day 14 through 21, and from postnatal day 1 through 21. The data show that significant vitamin A storage occurs in the fetal lung during the latter one-third of prenatal life. Depletion of these stores that begins before birth and continues into the early postnatal period suggests that the developing lung may be dependent on these local vitamin A stores during active growth and differentiation. The utilization of vitamin A stores in the developing lung appears to be independent of the liver stores of vitamin A.

Animals↗
PubMed1978

Effect of substrate composition and concentration on aortic cholesterol ester hydrolase activity.

Cholesterol ester hydrolase activity of pig aorta has been examined under optimum experimental conditions for hydrolysis of different cholesterol esters. The enzyme specific activity values were in the numerical order of substrates hydrolyzed: cholesteryl linoleate larger than or equal to linolenate greater than palmitate larger than or equal to stearate greater than oleate. The results are discussed in relation to the arterial accumulation of cholesterol esters.

Animals↗