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PubMed1976

Inhibition of glycolytic enzymes of rat liver and hepatomas by free fatty acids.

The action of free fatty acids on glycolytic enzymes was compared in normal and neoplastic tissues. Preincubation of tissue supernatant fractions with octanoate or laurate caused an inhibition of the activities of hexokinase and phosphofructokinase. An inhibition was also observed of lactate production with either glucose or glucose 6-phosphate as substrate. A similar degree of inhibition was observed for actions on normal liver and kidney, on the 7800 and 3924-A hepatomas and on the MK-3 renal cortical tumor. The possible relationship between the inhibition of glycolytic enzymes by fatty acids and anti-tumor activity previously observed with these compounds was noted.

Animals↗

PubMed2002

Physically cross-linked chitosan hydrogels as topical vehicles for hydrophilic drugs.

Physically cross-linked chitosan hydrogels with lauric, myristic, palmitic or stearic acid were prepared by freeze-drying and have been studied for topical use. This study selected propranolol hydrochloride as a hydrophilic model drug to design a transdermal delivery system. We evaluated the effect of the nature of the cross-linker on drug permeation through porcine skin and the main permeation parameters (diffusion coefficient, flux and lag time) were calculated. All the chitosan hydrogels analysed provided more transcutaneous permeation of propranolol hydrochloride than the corresponding solution of the commercial drug. Among the different chitosan vehicles, chitosan-laurate and chitosan-myristate hydrogels enhanced lyophilised drug diffusion through the skin with respect to chitosan-palmitate and chitosan-stearate hydrogels. This can been explained by the interaction of the hydrogels with the stratum corneum, increasing the solubility of the drug in the skin.

Administration, Cutaneous↗

PubMed1999

The effect of immunosuppressive agents (FK-506, rapamycin) on renal P450 systems in rat models.

It is well known that cyclosporin, rapamycin and FK-506 (tacrolimus) are metabolized by the liver microsomal cytochrome P450 enzyme system. Although there have been reports of interaction between these drugs and the renal P450 enzyme system, differences among these immunosuppressants has not been comprehensively demonstrated. We have studied the individual capacities of these immunosuppressants to induce renal microsomal P450 enzymes similar to CYP2B4 and CYP4A2 by examining renal function in treated rats, and have correlated the results by means of biochemical, immunological and immunohistochemical assays of renal P450 enzymes. Cyclosporin caused impairment of renal function with an increase in renal-specific P450 content, but FK-506 and rapamycin did not. Laurate omega- and (omega-1)-hydroxylase activity increased in rats treated with rapamycin but decreased in those treated with FK-506. Prostaglandin A1 (PGA1) omega-hydroxylase activity increased in rats treated with FK-506 but was reduced by treatment with cyclosporin. Aminopyrine N-demethylase activity increased in rats treated with cyclosporin or FK-506, but not in those treated with rapamycin. Western-blot analysis revealed significant induction of P450, (similar to CYP2B4 of the rabbit P450 isozyme) in kidneys from rats treated with cyclosporin but not in those from rats receiving FK-506 or rapamycin. Histochemical studies clearly demonstrated a form of P450 such as CYP4A2 in the proximal tubules of rats treated with cyclosporin, but not in those of rats treated with FK-506 or rapamycin. These results show that although cyclosporin has a strong effect on renal P450 systems and induces such a system in kidney cortex (microsomal P450), FK-506 and rapamycin have no substantial effect on the induction of renal P450. These findings might clarify the nephrotoxicity induced by these immunosuppressive drugs.

Aminopyrine N-Demethylase↗

PubMed1992

Inhibitory effect of OP-41483.alpha-CD, a prostacyclin analog, on peripheral vascular lesion models in rats.

The effect of a chemically stable prostacyclin analog, OP-41483 alpha-cyclodextrin clathrate (OP-41483.alpha-CD), on vascular lesions, platelet aggregation and blood pressure were examined and compared with those of prostaglandin E1 alpha-cyclodextrin clathrate (PGE1.CD) in in vivo rat models. 1) In the laurate (1 mg/leg, i.a.)-induced arterial thrombotic model, OP-41483.alpha-CD (1 microgram/kg/min, i.v.) prevented the progression of femoral arterial vascular lesions and enhanced the development of collaterals in the femoral artery. PGE1.CD did not inhibit the progression of vascular damages. 2) In the model of vasoconstriction induced by epinephrine (0.05 mg/tail, s.c.) and ergotamine (2 mg/kg, s.c.), OP-41483.alpha-CD and PGE1.CD, at 1 microgram/kg/min, inhibited the progress of of tail gangrene and lessened the decrease in tail cutaneous blood flow. 3) OP-41483.alpha-CD (1 microgram/kg/min) suppressed the ADP (0.1 mg/kg/min, i.v.)-induced decrease in the number of circulating platelets without affecting the change in blood pressure. In contrast, PGE1.CD (3 micrograms/kg/min) inhibited ADP-induced thrombocytopenia with a decrease in blood pressure. These results indicate that OP-41483.alpha-CD has antiplatelet and cutaneous blood flow improving activities that are greater than its hypotensive effect and may be of therapeutic potential in peripheral vascular diseases.

Alprostadil↗

PubMed2005

Enzymatic chemoselective synthesis of secondary-amide surfactant from N-methylethanol amine.

Efficient selective synthesis of the secondary amide surfactant N-methyl lauroylethanolamide from methyl laurate and N-methylethanol amine by carrier-fixed Chirazyme L-2 (Candida antarctica) using a kinetic strategy has been demonstrated. When different solvents were screened for product yields using Chirazyme L-2, acetonitrile was found to be optimal. The rate of the reaction increased sharply by increasing the molar ratio of the reactants and the reaction temperature. When the reaction was performed at 50 degrees C for 36 h with 50 mmol ester and 100 mmol amine, the product was obtained in a 97.1% yield. With 50 mmol ester and 150 mmol amine, the highest yield (97.3%) was obtained after 16 h of incubation at 50 degrees C. It took only 5 h to get a yield of 95.8% at 60 degrees C using 50 mmol ester and 200 mmol amine. The enzyme activity in the amidation reaction mixture did not decrease notably even after six uses.

Enzyme Activation↗

PubMed1983

Distribution and some characteristics of cytochrome P-450 in the kidney.

Intrarenal distribution of cytochrome P-450 (P-450) was investigated with different segments of isolated single nephrons from rabbits and rats by using a new ultra-micro method of P-450 determination. In both animals, P-450 was localized only in the proximal tubule. Other segments such as the glomerulus, the loop of Henle, the distal tubule, and the collecting tubule possessed no P-450 at all. Within the proximal tubule, the straight portion (S2 and/or S3 segments) revealed a higher specific content of P-450 than the convoluted one. An inducer of P-450, 3, 4-benzo(a)pyrene increased the P-450 of a definite portion (second 3 mm from the glomerulus) almost doubly in rabbits. In rats, both 3-methylcholanthrene (3MC) and 48 hr starvation (Fast) induced P-450, but only the later increased laurate-omega-hydroxylation. P-450 in the proximal convoluted and straight tubules was induced separately by Fast and 3MC, respectively. These results indicate that renal mixed function oxidase should be confined to the proximal tubule and that, like the liver, multiple forms of renal P-450 should exist in the different proximal segments.

Animals↗

PubMedDate not supplied

Microemulsions of triglyceride-based oils: The effect of co-oil and salinity on phase diagrams.

Microemulsification of triglyceride-based oil is challenging due to the formation of undesirable phases such as macroemulsions, liquid crystals, or sponge phases. This research evaluates the formation of artificial sebum microemulsions using linker molecules, with the addition of co-oil to help enhance sebum solubilization. The microemulsion consists of a lipophilic linker (sorbitan monooleate), a hydrophilic linker (hexylglucocide), a main surfactant (sodium dioctyl sulfosuccinate), a co-oil, and artificial sebum. The effect of adding co-oil to the phase behavior and the microstructure of the resulting microemulsion is described. The effect of several types of co-oil is also studied; the co-oils evaluated here are squalene, squalane, isopropyl myristate, and ethyl laurate. The effect of salinity on the microemulsion phase behavior is also presented. Fish diagrams are obtained by plotting total surfactant/linker concentration as a function of sebum fraction in the oil mixture (co-oil + sebum). Different microemulsion types (Winsor Types I, II, III, and IV) are formed, depending on the total surfactant/linker concentration and the fraction of co-oil in the oil mixture. Winsor Type IV (single-phase) microemulsions are observed at high surfactant/linker concentrations. These single-phase, isotropic, and low-viscous fluids are particularly useful for cleansing and delivery of functional ingredients in skin care products. Salt addition shifts the fish diagram towards more hydrophobic oil systems and higher surfactant/linker concentrations.

Cosmetics↗

PubMed1978

Contribution of omega-oxidation to fatty acid oxidation by liver of rat and monkey.

Contributions of omega-oxidation to overall fatty acid oxidation in slices from livers of ketotic alloxan diabetic rats and of fasted monkeys are estimated. Estimates are made from a comparison of the distribution of 14C in glucose formed by the slices from omega-14C-labeled compared to 2-14C-labeled fatty acids of even numbers of carbon atoms and from [1-14C]acetate compared to [2-14C]acetate. These estimates are based on the fact that 1) the dicarboxylic acid formed via omega-oxidation of a omega-14C-labeled fatty acid will yield [1-14C]acetate and [1-14C]succinate on subsequent beta-oxidation, if beta-oxidation is assumed to proceed to completion; 2) only [2-14C]acetate will be formed if the fatty acid is metabolized solely via beta-oxidation; and 3) 14C from [1-14C]acetate and [1-14C]succinate is incorporated into carbons 3 and 4 of glucose and 14C from [2-14C]acetate is incorporated into all six carbons of glucose. From the distributions found, the contribution of omega-oxidation to the initial oxidation of palmitate by liver slices is estimated to between 8% and 11%, and the oxidation of laurate between 17% and 21%. Distributions of 14C in glucose formed from 14C-labeled palmitate infused into fasted and diabetic rats do not permit quantitative estimation of the contribution of omega-oxidation to fatty acid oxidation in vivo. However, the distributions found also indicate that, of the fatty acid metabolized by the whole animal in the environment of glucose formation, at most, only a minor portion is initially oxidized via omega-oxidation. As such, omega-oxidation cannot contribute more than a small extent to the formation of glucose.

Acetates↗

PubMed1999

Interaction between fatty acid salts and elastin: kinetics, absorption equilibrium, and consequences for elasticity.

Elastin from bovine ligamentum nuchae is incubated in aqueous solutions of sodium salts of fatty acids (FAS). The FAS are laurate, myristate, and palmitate. Absorption of FAS in the elastin network is studied as a function of time, FAS concentration, and ionic strength. The consequences of this uptake for the elasticity of the elastin are studied by static and dynamic stress-strain measurements. Generally, distinction must be made between the initial time-dependent stage (I) and the final equilibrium stage (II). In I the initial rate of absorption follows a second-order binding mechanism, with the rate constant increasing with decreasing length of the FAS. In this regime, the elasticity modulus remains more or less unaffected. Especially in regime II the absorption of FAS is enhanced by a reduction in the cross-link density in the elastin network. This is ascribed to an osmotic pressure primarily caused by the concomitant uptake of low molecular weight ions in the elastin. The absorption equilibrium can be described by Langmuir theory. The absorption affinity increases with increasing hydrocarbon chain length of the FAS, indicating the contribution of hydrophobic interaction. Although the elasticity is not lost, the modulus is now reduced and a concomitant viscous component is developed.

Animals↗

PubMed1999

Lipase-catalyzed regioselective acylation of sucrose in two-solvent mixtures.

The enzymatic synthesis of 6-O-lauroylsucrose and 6-O-palmitoylsucrose was performed by transesterification of sucrose with the corresponding vinyl esters in a medium constituted by two solvents. More specifically, the acylation was carried out in 2-methyl-2-butanol (tert-amyl alcohol) containing a low percentage (not higher than 20%) of dimethyl sulfoxide. Several lipases were able to catalyze the transesterification, but that from Humicola lanuginosa (adsorbed on diatomaceous earth) was particularly useful. We optimized the synthesis of 6-O-lauroylsucrose varying the percentage and nature of the cosolvent, the molar ratio sucrose/vinyl laurate, the nature of bulk solvent and the enzyme content. Under the best conditions (2-methyl-2-butanol/DMSO 4:1 v/v), a sucrose conversion of 70% to 6-O-lauroylsucrose was achieved in 24 h using 50 mg biocatalyst/mL. As a side process, a low percentage (<5% in 24 h) of the initial sucrose is converted into the diesters 6,1'-di-O-lauroylsucrose and 6,6'-di-O-lauroylsucrose. The above methodology was also extended to the synthesis of 6-O-palmitoylsucrose. The acylation process was even faster, giving rise to an 80% conversion to monoester in 48 h using 25 mg biocatalyst/mL. This study shows that the use of two-solvent mixtures may become a feasible alternative for the synthesis of sucrose esters, allowing to exploit the catalytic potential of lipases.

Acylation↗

PubMed1990

On the latency and nature of phenoloxidase present in the left colleterial gland of the cockroach Periplaneta americana.

The phenoloxidase system responsible for the sclerotization of cockroach ootheca is found to be present as an inactive form in the left colleterial gland of Periplaneta americana. The supernatant fraction obtained by centrifugation of the milky white secretions contained the inactive phenoloxidase which required both sodium dodecyl sulfate (SDS) and the insoluble sediment for exhibiting enzyme activity. Bovine serum albumin could replace the sediment in the activation process. Proteins separated from the supernatant fraction by molecular sieve chromatography on Sephadex G-25 did not require either albumin or the sediment, but required SDS for exhibiting the phenoloxidase activity. Among the detergents tested, SDS (anionic) and cetylpyridinium chloride (cationic) activated the phenoloxidase, but CHAPS (zwitterionic) or nonionic detergents failed to activate the enzyme. The activation caused by SDS occurred well below the critical micellar concentration of SDS indicating that SDS is causing the activation by binding to the protein and altering its conformation. Chloroform-methanol extracts of vestibulum or right gland could replace SDS confirming the presence of endogenous activator(s) of phenoloxidase system. A variety of exogenously added lipids could activate the latent enzyme, among which linoleate, oleate, laurate, linolenate, phosphatidylethanolamine, and phosphatidylglycerol proved to be the effective activators of the latent phenoloxidase. Partially purified phenoloxidase was found to be extremely labile and lost its activity on a) freezing and thawing, b) dialysis, and c) heating for 10 min at 55 degrees C. It exhibited a pH optimum of 7 and was inhibited drastically by phenylthiourea and diethyldithiocarbamate. It readily oxidized a number of o-diphenols such as 3,4-dihydroxybenzylalcohol, 3,4-dihydroxyphenethyl alcohol, catechol, N-acetyldopamine, N-acetylnorepinephrine, dopa, dopamine, etc., but failed to oxidize both 3,4-dihydroxybenzoic acid and 3,4-dihydroxybenzaldehyde. It neither converted the typical laccase substrate syringaldazine to its quinone methide product, nor oxidized the p-diphenols, hydroquinone and methylhydroquinone. Therefore, the enzyme participating in the quinone tanning of cockroach ootheca appears to be a typical o-diphenol oxidase and not a laccase as previously thought.

Animals↗

PubMed1989

[The contents of sabal fruits and testing of their anti-inflammatory effect].

From sabal fruits the beta-sitosterolderivates beta-sitosterolpalmitate, -myristate,-laurate, -6-0-myristyl-beta-D-glucoside, -6-0-lauryl-beta-D-glucoside, -6-0-caprinoyl-beta-D-glucoside, -beta-D- -diglucoside and free beta-sitosterol as well as the flavonoids rutin, rhoifolin, isoquercitrin and kaempferol-3-0-glucoside were isolated. The pharmacological experiments showed that the polysaccharides, beta-sitosterol-derivatives and flavonoids were not involved in the anti-inflammatory effect of the perorally given drug.

Animals↗

PubMed2007

Can an inactivating agent increase enzyme activity in organic solvent? Effects of 18-crown-6 on lipase activity, enantioselectivity, and conformation.

Lipase from Burkholderia cepacia (lipase BC) and lipase B from Candida antarctica (CALB) show an increase of the transesterification activity in toluene (up to 2.4- and 1.7-fold, respectively), when lyophilized with 18-crown-6. Nevertheless, the increase was observed only for low (less than 100) 18-crown-6/lipase molar ratio, while at higher ratios, the activity decreased for both enzymes to values lower than those obtained in the absence of the additive. In 1,4-dioxane, the activation is lower for lipase BC (1.7-fold) and for CALB (1.5-fold). Concerning enantioselectivity, tested in the kinetic resolution of 6-methyl-5-hepten-2-ol, only in the case of CALB, an effect of the additive (the E value varied from about 120 to 280) was observed. In water, 4% (w/w) of 18-crown-6 caused a loss of activity in the hydrolysis of p-nitrophenyl laurate of about 88 and 99.75%, compared to that observed in the absence of the crown ether for CALB and lipase BC, respectively. These data and the conformational analysis of both lipases, carried out by FT/IR spectroscopy indicate that the enzyme inactivation in water and in organic solvents at 18-crown-6/lipase molar ratios, higher than 100 might be due to conformational changes caused by the additive. Instead, at molar ratios lower than 100, 18-crown-6 might increase the activity - particularly, in toluene - thanks to the fact that in its presence, the enzyme has an hydrogen bonds pattern, more similar to that in water. This suggests that the additive would be able to provide the enzyme with more water.

Burkholderia cepacia↗

PubMedDate not supplied

The antioxidant effect of hydroxyl-substituent Schiff bases on the free-radical-induced hemolysis of human erythrocytes.

The major objectives of the present work were focused on assessing the antioxidant capacities of two hydroxyl-substituent Schiff bases, 2-((o-hydroxylphenylimino)methyl)phenol (OSAP) and 2-((p-hydroxylphenylimino)methyl)phenol (PSAP) either used alone or in combination with some familiar water-soluble antioxidants i.e. 6-hydroxyl-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) and L-ascorbic acid (VC), and lipophilic ones i.e. alpha-tocopherol (TOH) and L-ascorbyl-6-laurate (VC-12). 2,2'-Azobis(2-amidinopropane hydrochloride) (AAPH). Induced hemolysis of human erythrocytes functioned as the evaluation experimental system in this research. The present findings showed that either OSAP or PSAP not only was an antioxidant with high activity in protecting erythrocytes against AAPH-induced hemolysis concentration-dependently, but can also protect erythrocytes by acting with Trolox, TOH, VC and VC-12 synergistically. Based on chemical kinetic deduction, the number of trapping peroxyl radicals, n, of the above-mentioned antioxidants can be calculated in relation to Trolox that traps two peroxyl radicals; thus, TOH can trap 3.83 peroxyl radicals, VC-12 traps 2.87 and VC can only trap 1.08. As for OSAP and PSAP, 8.71 and 13.7 peroxyl radicals can be trapped, respectively, indicating that they were the most efficient inhibitors against AAPH-induced hemolysis. Moreover, the total number of peroxyl radicals trapped by OSAP+Trolox, OSAP+TOH, OSAP+VC and PSAP+VC were higher than the sum of the above individual antioxidant used alone, demonstrating that a mutual promotive effect existed in the above mixed antioxidants. In contrast, owing to the fact that the total number of peroxyl radicals trapped by OSAP+VC-12, PSAP+Trolox, PSAP+TOH and PSAP+VC-12 were less than the sum of the above individual antioxidant used alone, a mutual antagonistic effect was suggested in these combinative usages. This information may be helpful in the pharmaceutical application of two Schiff bases.

Ascorbic Acid↗

PubMedDate not supplied

Insight into the free-radical-scavenging mechanism of hydroxyl-substituent Schiff bases in the free-radical-induced hemolysis of erythrocytes.

This work aimed to explore the mechanism by which hydroxyl-substituent Schiff bases scavenge free-radicals. Thus, four Schiff bases, that is benzylidene aniline (BAN), 2-(phenyliminomethyl)phenol (BAH), 4-benzimidoylphenol (PBH) and 2-benzimidoylphenol (OBH), were applied to protect human erythrocytes against 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced hemolysis. The results revealed that the --OH attached to the ortho-position of methylene in Schiff base scavenges 1.46 radicals per molecule, the --OH attached to the para-position of the N atom scavenges 2.94 radicals and the --OH attached to the ortho-position of the N atom scavenges 3.63 radicals. In addition, four Schiff bases were used together with some familiar antioxidants, such as 6-hydroxyl-2,5,7,8-tetramethyl chroman-2-carboxylic acid (Trolox), L-ascorbic acid (VC), alpha-tocopherol (TOH) and L-ascorbyl-6-laurate (VC-12) in AAPH-induced hemolysis of erythrocytes. It was found that, except for BAN+VC-12, BAH + VC-12, OBH + VC-12 and PBH+TOH, all the other combinations protected erythrocytes more perfectly than when used individually. This result demonstrated that a promotive protection existed between Schiff base and other antioxidants and this improved their ability to scavenge free-radicals. Finally, IC(50) values of the aforementioned Schiff bases together with 2-((o-hydroxylphenylimino) methyl)phenol (OSAP) and 2-((p-hydroxylphenylimino)methyl)phenol (PSAP) were determined by reaction with two radical species, that is, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) radical (ABTS(+.)) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH). The results implied that the molecular framework of a Schiff base and an --OH attached to the ortho-position of methylene were apt to reduce radicals, but the --OH attached to the aniline ring in a Schiff base was prone to scavenge radicals directly.

Amidines↗

PubMed2003

Behavior of silica aerogel networks as highly porous solid solvent media for lipases in a model transesterification reaction.

Highly porous silica aerogels with differing balances of hydrophobic and hydrophilic functionalities were studied as a new immobilization medium for enzymes. Two types of lipases from Candida rugosa and Burkholderia cepacia were homogeneously dispersed in wet gel precursors before gelation. The materials obtained were compared in a simple model reaction: transesterification of vinyl laurate by 1-octanol. To allow a better comparison of the hydrophobic/hydrophilic action of the solid, very open aerogel networks with traditional organic hydrophobic/hydrophilic liquid solvents, this reaction was studied in mixtures containing different proportions of 2-methyl-2-butanol, isooctane, and water. The results are discussed in relation to the porous and hydrophobic nature of aerogels, characterized by nitrogen adsorption. It was found that silica aerogels can be considered as "solid" solvents for the enzymes, able to provide hydrophobic/hydrophilic characteristics different from those prevailing in the liquid surrounding the aerogels. A simple mechanism of action for these aerogel networks is proposed.

Adjuvants, Pharmaceutic↗

PubMed1980

Flow cytometric determination of esterase and phosphatase activities and kinetics in hematopoietic cells with fluorogenic substrates.

Viable and formaldehyde fixed rat bone marrow or spleen cells and rat or human blood leukocytes were incubated with fluorescein (fluorescein-diacetate, -dibutyrate and -laurate) or umbelliferone (4-methyl umbelliferyl acetate and -phosphate) fluorogenic substrates for subsequent flow cytometric determination of cell fluorescence and cell volume. Formaldehyde-fixed cells preserved between 14 and 20% of the enzyme activity of the unfixed cells and the number of cell clusters for fixed and unfixed cells was the same. The esterase substrates revealed one cell cluster for spleen cells, two for bone marrow cells and four for peripheral blood leukocytes. Phosphatase activity was only associated with a cell cluster of large cells. The time course of substrate cleavage was linear during the first 10 min of incubation. Later on a plateau was reached. Specific enzyme activities were calculated on a single cell level from the simultaneous cell volume and cell fluorescence measurement. Two enzyme activities could be measured simultaneously by using a substrate mixture of umbelliferone acetate and fluorescein acetate.

Animals↗

PubMed1990

Effect of exogenous fatty acids on lipid synthesis, marker-enzymes, and development of glial cells maintained in serum-free culture.

Glial cells were isolated from the cerebra of 7-day-old rats and maintained in culture in a chemically defined medium that favours the development of oligodendrocytes. Acetate, butyrate, or albumin-bound hexanoate, octanoate, decanoate, laurate, myristate, palmitate, oleate, linoleate, or arachidonate was added to the culture medium. The incorporation of [3H]acetate into fatty acids and cholesterol and [35S]sulphate into sulphatide, and the activities of the oligodendrocyte marker enzymes 2',3'-cyclic-nucleotide 3'-phosphodiesterase and glycerol 3-phosphate dehydrogenase were measured. The composition of the glial cell population (the number of astrocytes and oligodendrocytes) in these cultures was studied by immunocytochemistry. Results show that 1) long-chain fatty acids depress the synthesis of fatty acids, cholesterol, and sulphatide; and 2) the presence of long-chain, in contrast to short-chain, fatty acids in the culture medium lowers the activities of 2',3'-cyclic-nucleotide 3'-phosphodiesterase and glycerol 3-phosphate dehydrogenase and decreases the number of oligodendrocytes. Our results suggest that long-chain fatty acids exert a negative influence on the development of oligodendrocytes in the culture system used.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗