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At least 757 records · Page 42Linked to original sources
PubMed1979

Effects of diets of homogeneous saturated triglycerides on cholesterol balance in rats.

The effects of a diet of 10% homogeneous triglycerides of 12 to 18-carbon chain saturated fatty acids on cholesterol absorption and turnover were studied in rats. Cholesterol absorption was successively significantly less in rats fed tristearin than in groups fed tripalmitin, trimyristin and trilaurin. Lesser fatty acid absorption may explain the differences in part, since cholesterol absorption was significantly correlated with fat absorption. Cholesterol removal from plasma was fastest in rats fed tristearin. Plasma cholesterol levels were increased with the trilaurin diet although the rate of cholesterol accumulation in lymph after gavage was slower with trilaurin. Lymph triglycerides were highest with trilaurin and trimyristin diets perhaps indicating endogenous mobilization of triglyceride for lipoprotein formation. Lymph triglycerides were, however, decreased with tristearin. Sterol turnover (production, absorption plus synthesis) was increased with tristearin or trilaurin by kinetic or balance methods.

Animals↗
PubMed1978

Aliesterase activity in normal and postheparin human blood sera.

An enzyme with characteristics typical of aliesterase has been found in human blood serum using a gas solid chromatographic assay technique. This conflicts with the findings of several authors that aliesterase is absent in the human blood. Another aliesterase is released into the blood stream after intravenous administration of heparin. Partial purification of the aliesterase in normal (preheparin) and postheparin sera was effected by column chromatography using CM- and DEAE-Sephadex. The preheparin aliesterase and postheparin aliesterase have different pH optima of 7.0 and 8.5 respectively. The preheparin aliesterase activity was very sensitive to sodium fluoride and insensitive to a negatively charged detergent, sodium lauryl sulfate, unlike the postheparin esterase which was highly sensitive to sodium lauryl sulfate and comparatively less sensitive to sodium fluoride.

Butyrates↗
PubMed2005

Oleoylethanolamide protects human sperm cells from oxidation stress: studies on cases of idiopathic infertility.

N-acylethanolamides are naturally occurring hydrophobic molecules usually present in a very small amount in many mammalian tissues and cells. The presence of N-acylethanolamides has also been demonstrated in human reproductive tracts and fluids, although their biological effects and molecular mechanisms of action are not yet completely elucidated. It is known that some N-acylethanolamides, such as oleoylethanolamide, have antioxidative properties. The aim of this study was to test whether oleoylethanolamide could protect sperm cells from reactive oxygen species-induced oxidative damage in cases of idiopathic infertility, because the excessive generation of these radicals was associated with this pathology. Our results show that 2.5 nM oleoylethanolamide in vitro supplementation significantly reduces DNA strand breaks both in fertile and infertile subjects. Moreover, oleoylethanolamide increases kinematic parameters, such as curvilinear velocity and amplitude of lateral head displacement and hyperactivation, both in the presence and in the absence of oxidative stress. Results of this study support the hypothesis of a possible protective action of oleoylethanolamide against reactive oxygen species, which could explain its beneficial effects on in vitro capacitated spermatozoa.

2-Naphthylamine↗
PubMed2003

Conditional preparation of a quantum state in the continuous variable regime: generation of a sub-Poissonian state from twin beams.

We report the first experimental demonstration of conditional preparation of a nonclassical state of light in the continuous variable regime. Starting from a nondegenerate optical parametric oscillator which generates above threshold quantum intensity correlated signal and idler "twin beams," we keep the recorded values of the signal intensity only when the idler intensity falls inside a band narrower than its standard deviation. By this very simple technique, we generate a sub-Poissonian state 4.4 dB (64%) below shot noise from twin beams exhibiting 7.5 dB (82%) of noise reduction in the intensity difference.

Journal Article↗
PubMed2006

Direct measurement of decoherence for entanglement between a photon and stored atomic excitation.

Violations of a Bell inequality are reported for an experiment where one of two entangled qubits is stored in a collective atomic memory for a user-defined time delay. The atomic qubit is found to preserve the violation of a Bell inequality for storage times up to 21 micros, 700 times longer than the duration of the excitation pulse that creates the entanglement. To address the question of the security of entanglement-based cryptography implemented with this system, an investigation of the Bell violation as a function of the cross correlation between the generated nonclassical fields is reported, with saturation of the violation close to the maximum value allowed by quantum mechanics.

Journal Article↗
PubMed2003

Crystallization of the bovine ADP/ATP carrier is critically dependent upon the detergent-to-protein ratio.

The ADP/ATP carrier is an integral membrane protein located in the mitochondrial inner membrane. It mediates the exchange of cytosolic ADP for ATP generated in the mitochondrial matrix. Here, the purification and crystallization of the bovine ADP/ATP carrier in complex with the inhibitor carboxyatractyloside in the presence of LAPAO, an aminoxide detergent, is reported. High-quality crystals were only obtained when excess detergent was removed to reach a controlled detergent-to-protein ratio.

Animals↗
PubMed1987

Surfactants cause in vitro chemotaxis and chemokinesis of human neutrophils.

The surfactant sodium lauryl sulfate (SLS) and alkyldimethylbenzylammonium chloride (ADB) cause erythema and leukocyte infiltration on epicutaneous application. To elucidate the mechanism of this inflammatory response, the in vitro effect of the same agents was studied on human neutrophil migration, basophil histamine release, and leukocyte lysosomal enzyme (beta-glucuronidase) release. At concentrations of greater than 0.02%, both surfactants were cytotoxic, as was evident by decreased eosin exclusion, massive histamine and beta-glucuronidase-release, and absent migration of cells. At dilutions of less than 0.002% of both surfactants, viability of cells was normal, and small amounts of histamine and beta-glucuronidase were released at a dilution of 0.001%. The most striking finding was a dose-dependent chemotactic and chemokinetic response at dilutions from 10(-3) to 10(-8)%. These observations offer a possible explanation for the pathomechanisms of irritant dermatitis due to surfactants.

Benzalkonium Compounds↗
PubMed1990

Activation process of macrophages after in vitro treatment of mouse lymphocytes with dodecylglycerol.

Alkylglycerols, inflammation products of cancerous membrane lipids, efficiently activate macrophages. A brief in vitro treatment (30 min) of peritoneal cells (mixture of non-adherent and adherent cells) with a small amount (50 ng/ml) of synthetic dodecylglycerol (DDG) resulted in greatly enhanced Fc-receptor-mediated ingestion activity of macrophages. However, treatment of adherent cells (macrophages) alone with DDG produced no significant enhancement of macrophage ingestion activity, implying that macrophage activation requires a contribution of non-adherent cells. DDG-treated non-adherent cells were found to generate a macrophage-activating signal factor. Studies with a serum free-0.1% egg albumin-supplemented RPMI 1640 medium revealed that a serum factor is essential for macrophage activation process. Time course analysis of stepwise transfers of conditioned media of DDG-treated or untreated B cells and T cells revealed that DDG-treated B cells rapidly transmit a factor to untreated T cells which yield the ultimate macrophage-activating factor. This signal transmission among these cells for the macrophage activation process is too rapid to allow time for synthesis of inducible gene products. Thus, we hypothesized that a serum factor is modified by the pre-existing function of DDG-treated B cells and further modified by the pre-existing function of untreated T cells to yield macrophage-activating factor. This hypothesis was confirmed by the demonstration that DDG-treated splenic non-adherent cell ghosts modify a serum factor to yield macrophage-activating factor.

Animals↗
PubMed1979

Effects of amphiphiles on structure and activity of human erythrocyte membrane acetylcholinesterase.

Detergents above their critical micellar concentration dissociate the aggregated forms of pure acetylcholinesterase from human erythrocyte membranes to a 6.5-S form, the protomer. This form is active only in presence of amphiphiles. 1. Uncharged (Triton X-100, Tweens, beta-D-octylglycoside), anionic (sodium dodecyl sulfate) and zwitterionic (lysophosphatidylcholine) detergents or bile salts (sodium cholate, deoxycholate) stabilize the 6.5-S enzyme at concentrations well below their critical micellar concentration. 2. Total erythrocyte lipids fully sustain catalytic activity of the 6.5-S form. 3. Protein-protein interactions stabilize the activity of the 6.5-S form of acetylcholinesterase. Above a critical acetylcholinesterase concentration (2.5 microgram/ml) enzyme activity no longer depends on the presence of an amphiphile as reaggregation to multiple molecular forms occurs. It is concluded that human erythrocyte membrane acetylcholinesterase is fully active only if the enzyme can undergo hydrophobic interactions with amphiphiles such as detergents, lipids or proteins.

Acetylcholinesterase↗
PubMed2006

Synthesis of poly (3-hydroxybutyrate-co-3-hydroxyoctanoate) by a Sinorhizobium fredii strain.

AIMS: The potential of a Sinorhizobium fredii strain to produce a copolymer from glucose and sodium dodecanoate substrates was investigated. METHODS AND RESULTS: Using an orthogonal design in a flask-shaker culture system, the vital regulation conditions for copolymer synthesis were optimized. These optimal results were applied to further studies in a two-stage fed-batch fermentation with a 10-l fermentor. When the biomass approached 33.5 g l(-1) dry cells at 35 h, 7 mmol l(-1) sodium dodecanoate was added into the broth to trigger the copolymer synthesis. After further culturing for 3 h, the copolymer product could be 17.14 g l(-1). The molecular structure of the copolymer was determined to be a poly (3-hydroxybutyrate-co-3-hydroxyoctanoate) [P (HB-HO)] by nuclear magnetic resonance. The content of HB and HO in P (HB-HO) was 79.2% (w/w) and 20.8% (w/w) respectively. The molecular weight of the P (HB-HO) was measured as 1.85 x 10(5) Da by a viscosity method. CONCLUSION: The results demonstrated that the S. fredii strain used could be a potential candidate for the industrial production of the copolymer. SIGNIFICANCE AND IMPACT OF THE STUDY: Some basic fermentation parameters were acquired through the fed-batch culturing experiments and they should be applicable in developing large-scale fermentation technologies for producing the P (HB-HO) copolymers.

Glucose↗
PubMed1999

Co-expression of polyhydroxyalkanoate synthase and (R)-enoyl-CoA hydratase genes of Aeromonas caviae establishes copolyester biosynthesis pathway in Escherichia coli.

Polyhydroxyalkanoate biosynthesis genes of Aeromonas caviae were expressed in Escherichia coli LS5218 (fadR atoC(Con)), and the polyhydroxyalkanoate-producing ability of the recombinants was investigated. A LS5218 strain harboring only phaCAc (polyhydroxyalkanoate synthase gene) did not accumulate any polyhydroxyalkanoate from dodecanoate in spite of the existence of translated polyhydroxyalkanoate synthase protein, whereas co-expression phaCAc and phaJAc ((R)-specific enoyl-CoA hydratase gene) resulted in the accumulation of P(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer up to 7-11 wt% of dry cell weight from octanoate and dodecanoate. These results indicated that both phaCAc and phaJAc are essential for E. coli LS5218 to establish the polyhydroxyalkanoate biosynthesis pathway from alkanoic acids. The copolyester content in the strain expressing both the genes under the lac promoter control reached to 38 wt% from dodecanoate. Enzyme assays suggest that efficient monomer formation via beta-oxidation by a high level expression of phaJAc was important to achieve a high polyhydroxyalkanoate content in the recombinant E. coli.

Acyltransferases↗
PubMed1999

Co-expression of 3-ketoacyl-ACP reductase and polyhydroxyalkanoate synthase genes induces PHA production in Escherichia coli HB101 strain.

The Escherichia coli 3-ketoacyl-ACP reductase gene (fabGEc) was cloned using a PCR technique to investigate the metabolic link between fatty acid metabolism and polyhydroxyalkanoate (PHA) production. Three plasmids respectively harboring fabGEc and the poly-3-hydroxyalkanoate synthesis genes phaCAc and phaC1Ps from Aeromonas caviae and Pseudomonas sp. 61-3 respectively were constructed and introduced into E. coli HB101 strain. On a two-stage cultivation using dodecanoate as the sole carbon source, recombinant E. coli HB101 strains harboring fabGEc and phaC genes accumulated PHA copolymers (about 8 wt% of dry cell weight) consisting of several (R)-3-hydroxyalkanoate units of C4, C6, C8, and C10. It has been suggested that overexpression of the fabGEc gene leads to the supply of (R)-3-hydroxyacyl-CoA for PHA synthesis via fatty acid degradation.

3-Oxoacyl-(Acyl-Carrier-Protein) Reductase↗
PubMed1993

Modulation and dynamics of phase properties in phospholipid mixtures detected by Laurdan fluorescence.

Steady-state and dynamic fluorescence properties of 6-lauroyl-2-dimethylaminonaphthalene (Laurdan) have been used to ascertain the coexistence of separate phase domains and their dynamic properties in phospholipid vesicles composed of different mole ratios of dilauroyl- and dipalmitoyl-phosphatidylcholine (DLPC and DPPC, respectively). The recently introduced generalized polarization together with time-resolved emission spectra have been utilized for detecting changes. The results indicate the coexistence of phospholipid phase domains in vesicle compositions in the range between 30 mol% and 70 mol% DPPC in DLPC. Below and above these concentrations a homogeneous phase is observed, with averaged properties. In the case of coexisting phase domains, the properties of each individual phase are largely influenced by the presence of the other phase. Implications on fluctuations between the coexisting phases and on the size and shape of domains are discussed.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

Lipid phases in renal brush border membranes revealed by Laurdan fluorescence.

Steady-state fluorescence properties of 6-dodecanoyl-2-dimethylaminonapththalene (Laurdan) have been used to determine the coexistence of separate lipid-phase domains in apical brush border membrane vesicles isolated from the rat renal cortex. The temperature dependence of generalized polarization has been utilized to quantitate the lipid phases. Finally, the effect of cholesterol enrichment on these parameters has been studied. The results indicate the coexistence of lipid-phase domains in brush border membranes based on the values of the generalized polarization and assuming that the membrane state can be described by coexistence of gel and liquid crystalline state. At 37 degrees C, approximately 19-32% of the brush border membrane lipids are in the gel phase, and cholesterol enrichment causes a further concentration-dependent increase in the gel phase of brush border membrane lipids.

2-Naphthylamine↗