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Results for “PALMITIC ACID”

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PubMed2004

Effects of palmitic acid and cholesterol on proton transport across black lipid membranes.

We studied the effect of palmitic acid (PA) and cholesterol (approximately 17 wt.%) on proton translocation across asolectin (charged) and diphytanoylphosphatidylcholine (DPhPC, neutral) black lipid membranes (BLMs). Potential difference (PD), short circuit current (SCC), and conductance (G(total)) were measured with a digital electrometer. Membranes were exposed to pH gradients (0.4-2.0 units), followed by PA addition to bath (symmetrically, 40-65 microM). The membrane conductive pathway was subdivided into an unspecific and a proton-related routes. A computer program estimated the conductances (G(un) and G(H)) of the two pathways from the measured parameters. No significant differences in proton selectivity were found between DPhPC membranes and DPhPC/cholesterol membranes. By contrast, cholesterol incorporation into asolectin increases membranes selectivity to proton. Cholesterol dramatically reduced G(un) reflecting, probably, its ability of inducing order in lipid chains. In asolectin membranes, PA increases proton selectivity, probably by acting as a proton shuttle according to the model proposed by Kamp and et al. [Biochemistry 34 (1995) 11928]. Cholesterol incorporation into asolectin membranes eliminates the PA-induced increase in proton selectivity. In DPhPC and DPhPC/cholesterol membranes, PA does not affect proton selectivity. These results are discussed in terms of the presence of cardiolipin (CL) in asolectin, cholesterol/PA interactions, and cholesterol order-inducing effects on acyl-chains.

Cell Membrane↗

PubMed2000

The effect of palmitic acid on lipoprotein cholesterol levels.

The present study assessed the effect of high versus low palmitic acid intakes of plasma lipoprotein cholesterol levels and on rates for endogenous synthesis of cholesterol in normal and hypercholesterolemic subjects. On day 21 of each diet treatment, a fasting blood sample was drawn for lipoprotein determination and to provide a measure of the background level of deuterium. A priming dose of deuterium was consumed and a second blood sample obtained 24 hours after the first sample. Isotope ratio mass spectrometry was used to determine the incorporation of deuterium into the newly synthesized cholesterol molecule and fractional synthetic rates were calculated. Four diets were formulated to provide combinations of two levels of 16:0 at two levels of 18:2n-6. Subjects received each of the four diet treatments for 21 days, followed by washout periods of 21 days. Serum total cholesterol and LDL-cholesterol was not significantly affected by the high level of 16:0 when diets also contained a high level of 18:2n-6. Fractional synthesis rates of cholesterol observed for each diet treatment did not differ significantly, suggesting no relationship between the endogenous synthesis of cholesterol and dietary 16:0 content. The results indicate that 16:0 has no effect on serum lipoprotein profiles in the presence of recommended intakes for 18:2n-6.

Adult↗

PubMed1995

Protection of vitamin E, selenium, trolox C, ascorbic acid palmitate, acetylcysteine, coenzyme Q0, coenzyme Q10, beta-carotene, canthaxanthin, and (+)-catechin against oxidative damage to rat blood and tissues in vivo.

Male Sprague-Dawley rats were fed either a vitamin E and selenium deficient diet, a diet supplemented with vitamin E and selenium, or a diet supplemented with vitamin E, selenium, trolox C, ascorbic acid palmitate, acetylcysteine, Beta-carotene, canthaxanthin, coenzyme Q0, coenzyme Q10, and (+)-catechin. Rats were injected with CBrCl3 (0.05 mmol/100 g body weight) intraperitoneally. Oxidative damage to tissues was measured by formation of oxidized heme proteins (OHP) in blood, liver, kidney, heart, lung, and spleen. Diets supplemented with antioxidants showed protection against oxidative damage caused by CBrCl3. The protection was dependent on the diversity and quantity of antioxidants in the diet. In general, diets supplemented with both fat soluble and water soluble antioxidants provided better protection than diets supplemented only with vitamin E and selenium or with vitamin E, selenium, and fat soluble antioxidants.

Acetylcysteine↗

PubMed2001

Acute inhibition of proinsulin biosynthesis at the translational level by palmitic acid.

The effects of fatty acids on pancreatic beta cell are still controversial. Here, in order to determine whether free fatty acids acutely affect beta cell functions, we studied the effect of palmitic acid (PA) on proinsulin biosynthesis and insulin secretion using rat islets in vitro. Exposure of islets to PA for 1 h reduced glucose-stimulated proinsulin biosynthesis in a dose-dependent manner; in contrast, no change in insulin secretion was observed after 1 h incubation with PA. Furthermore, PA treatment did not cause any change of preproinsulin mRNA level during 1-h incubation period. Thus, our data indicate that PA primarily suppresses glucose-induced proinsulin biosynthesis within 1 h at the translational level.

Animals↗

PubMed2004

[Palmitic acid induces apoptosis in human hepatoma cell line, HepG2 cells].

OBJECTIVE: To investigate the effects of palmitic acid (PA) on human hepatocytes and its mechanism. METHODS: We administered a mimic hyperlipidemia condition of 0.2-0.4 mmol/L PA to human hepatoma cell line, HepG2 cells. Cell viability was determined by Trypan blue staining. Cell cycle and early apoptosis were determined by propidium iodide and/or Annexin V staining, and the levels of Bcl-2 and Bax were analyzed by flow cytometry. RESULTS: An inhibition of cell growth was observed at a dose- and time-dependent manner in HepG2 cells after the treatment of PA. An apoptosis with appearance of sub-G1 fraction determined by cell cycle analysis significantly increased after the treatment of PA for 4 days. Bcl-2 level slightly decreased; in contrast, Bax level elevated markedly, which resulted in a significant decrease of Bcl-2/Bax ratio. CONCLUSION: PA may induce cell death on hepatocytes via mitochondria-mediated apoptosis by reducing the level of Bcl-2/Bax.

Apoptosis↗

PubMed2002

AFM nanolithography on a mixed LB film of hexadecylamine and palmitic acid.

An evenly mixed Langmuir film of hexadecylamine (HDA) and palmitic acid (PA) was prepared on the air-water interface and transferred to a Si substrate for the fabrication of nano-sized patterns. Vibrational spectrum of the transferred film shows that all acid groups of PAs were deprotonated and amine groups of HDAs were protonated by an acid-base reaction. The effect of mixing ratios in atomic force microscopy anodization lithography on the mixed films was investigated in terms of the line width of the protruded pattern. While the line width fabricated on PA film was 221 nm, the width on the mixed film was reduced to 84 nm under the same lithographic conditions. It is believed that the phenomenon was originated from the mixed structure from the interaction of HDA and PA. The chemical composition difference caused by the presence of ammonium cation in resist resulted in reducing the line width fabricated in the mixed Langmuir-Blodgett film.

Journal Article↗

PubMed1978

[Distribution of 1-14C palmitic acid in brain tissue after intraventricular injection in the conscious cat].

The distribution of (1-14C) palmitic acid in the brain tissue following the injection into the cerebral ventricles of conscious cats was investigated. The radioactive material was found in the brain tissue surrounding the cerebral ventricles and in the cerebral cortex, but in varying amounts : the smallest amounts were found in the cerebral cortex, while the highest in the thalamus and in the hippocampus. Radioactive material was also found in the peripheral venous blood. The amount of the radioactive material in the grey matter lining the cerebral ventricles as well as in the cerebral cortex was time-dependant. The labelled material in the structures surrounding the cerebral ventricles and in the cerebral cortex increased within first four hours after its intraventricular administration. Thereafter, throughout subsequent 48 hours either it slowly disappeared in the caudate nucleus and in the thalamus, or it was retained in the hypothalamus and in the floor of the IV ventricle.

Animals↗

PubMedDate not supplied

[Formation of primary alcohols and palmitic acid in the microbiological oxidation of hexadecane].

Forty seven microbial strains oxidized hexadecane to form primary cetol and palmitic acid. The maximum quantitiy of the compounds was accumulated in the exponential phase of growing cultures (for 72 hours) and for 6 to 16 hours of incubation of resting cell suspensions. Candida yeast were shown by the gas-liquid chromatography method to be the most active producers of cetol.

Alcohols↗

PubMed1993

The G protein alpha s subunit incorporates [3H]palmitic acid and mutation of cysteine-3 prevents this modification.

We investigated whether alpha s could be acylated by palmitate by transfecting COS cells with the cDNA for the wild-type, long form of alpha s and metabolically labeling with [3H]palmitate or [35S]methionine. Cells were separated into particulate and soluble fractions and immunoprecipitated with a specific peptide antibody. [3H]Palmitate was incorporated into both endogenous and transfected alpha s. Inhibition of protein synthesis with cycloheximide did not block the radiolabeling of alpha s with [3H]palmitate. Hydroxylamine treatment caused a release of the tritium radiolabel, demonstrating that the incorporation was through a thioester bond. The tritium radiolabel was base-labile and comigrated with [3H]palmitate on thin-layer chromatography. The third residue of the wild-type alpha s was mutated from a cysteine to an alanine by site-directed mutagenesis. This mutant was expressed in COS cells and localized to the particulate fraction as determined by immunoprecipitation of the [35S]methionine-labeled cells. The cysteine-3 mutant did not undergo radiolabeling with [3H]palmitate, indicating that this residue is crucial for the modification.

Animals↗

PubMedDate not supplied

[Palmitic acid in amniotic fluid and its relation with gestational age and neonatal R.D.S. (author's transl)].

503 samplings of palmitic acid in amniotic fluid are correlated with gestational age during labor or not. In nine cases of R.D.S. determinations during labor were of very low values, but not in those before labor started. Results are discussed, indicating that values over 2 mg./100 ml. show adequate pulmonary maturity. Inferior values would only be valuable if samples are obtained during labor.

Amniotic Fluid↗

PubMed1983

Bacterial hydrophobicity measured as partition of palmitic acid between the two immiscible phases of cell surface and buffer.

Bacterial hydrophobicity was measured as the affinity of palmitic acid to the cell surface. Cell surface and buffer were regarded as two immiscible phases with different affinity for the fatty acid. After equilibration of the system, the partition quotient (PQ) between the two phases was calculated. The bacteria hydrophobicity was expressed as the amount of cell mass required to give a partition quotient of 10 between amount of fatty acid bound to cell surface and amount of fatty acid in buffer (PQ 10). This system permits measurement of changes in hydrophobicity during bacterial growth as shown for Staphylococcus aureus, strain V 8. The hydrophobicity of this bacterium increased 4-5 times during the exponential growth-phase of the culture. In the stationary growth-phase there was a loss of hydrophobicity, which continued for at least 48 hours, linearly with time. The system was also tested with a Salmonella typhimurium strain and its rough mutant. The results were consistent with findings in other test systems measuring the hydrophobicity of these bacteria.

Bacteria↗

PubMed1980

Palmitic acid transport in platelets of normal subjects and of patients with liver cirrhosis.

Bovine serum albumin bound 14C-palmitic acid (BSA-14C-PA) is transported into platelets of normal and cirrhotic subjects by simple diffusion. Initial uptake increases linearly with the concentration of BSA-14C-PA in the medium. The time course accumulation of BSA-14C-PA is found to be higher in the platelets of patients with cirrhosis compared to that of normals. At 50-min incubation, the amount of 14C-PA accumulated in the platelets of cirrhotic subjects is 52.43 +/- 7.40 nmol/10(9) platelets and in the platelets of normal controls it is 22.71 +/- 3.14 nmol/10(9) platelets. The diffusion rate of BSA-14C-PA is also higher in the platelets of cirrhotic patients where the slope of the concentration dependency curve for 10(9) platelets at 30 sec is 56.0 +/- 4.8 X 10(-4) liters. This value is 21.6 +/- 2.4 X 10(-4) liters for normal subjects.

Biological Transport↗

PubMed1976

[Effect of gamma rays from 60Co on the in vitro incorporation of palmitic acid in lipids of rat liver microsomes].

The gamma-rays of 60Co cause a diminution in the incorporation of palmitic acid in the phosphatidic acids and the neutral fats of rat-liver microsomes. This diminution occurs without morphological change in the microsomal membranes, where the enzymes responsible for this incorporation are situated. Some evidence is offered that lipid peroxides may be involved in this inhibition.

Animals↗

PubMed1995

Feeding premature newborn infants palmitic acid in amounts and stereoisomeric position similar to that of human milk: effects on fat and mineral balance.

The effect of the structure of human milk triglycerides on intestinal fat absorption remains controversial. Twelve infants were each fed, for 1 wk in a crossover design, two formulas that differed only in triglyceride configuration. The "beta" formula contained triglycerides similar to those in human milk (26% palmitic acid, esterified predominantly to the sn-2 position) whereas in the "alpha" formula, which contained triglycerides similar to those in formulas currently marketed, palmitate was mainly at the sn-1,3 positions. Fatty acid, fat, and mineral balances were measured at the end of each 1-wk period. Myristic, palmitic, and stearic acids were absorbed better from the beta formula, but total fat excretion was not reduced. During the feeding of beta formula fecal calcium excretion was lower, urinary calcium higher, and urinary phosphate lower. A formula containing triglycerides similar to those in human milk has significant effects on fatty acid intestinal absorption and improves mineral balance in comparison with a conventional formula.

Administration, Oral↗

PubMed1949