Showing papers by "National University of La Plata published in 1980"
TL;DR: The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition and the Δ6 and Δ5 desaturases were inhibited by ethanol whereas the Δ9 desaturase and fatty acid synthetase were apparently modified only by diet composition.
Abstract: The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition. Acute ethanol administration increased triacylglycerols of total liver lipids, but did not modify significantly the lipidic composition of microsomes. The Δ6 and Δ5 desaturases were inhibited by ethanol whereas the Δ9 desaturase and fatty acid synthetase were apparently modified only by diet composition. NADH-cytochrome (cyt.) c reductase was partially inhibited, whereas NADH-cyt. b5 reductase remained practically unaltered and NADPH-cyt. c reductase activity was enhanced. Decreased electrons supplied by the microsomal cyt. b5 electron transport chain would not be the reason for the inhibition of Δ6 and Δ5 desaturases by ethanol.
144 citations
TL;DR: It is evident from the current investigation that partial deprivation of protein during early development may impair the conversion of linoleate to arachidonate in the rat and that the lack of arachidonic acid observed in the liver cells during protein deficiency would be the consequence of this impairment.
Abstract: The influence of protein restriction and EFA deficiency during early development in the rat on the activities of delta 5, delta 6 and delta 9 desaturases was studied. The effect of these diets on body weights and in the fatty acid composition of liver phospholipids was also investigated. The results indicate that the body weights of pups were lowered by feeding the dams both the low-protein and the EFA-deficient diet. The activities of delta 5, delta 6 and delta 9 desaturases were reduced in about 60% by protein deficiency but a rise in the activity of delta 9 desaturase of 362.2% was promoted by feeding the dams the low-fat diet. The fatty acid composition of liver phospholipids indicates that partial deprivation of proteins during early development is associated with a decreased ratio of arachidonate to linoleate. Besides the low-fat group shows in the fatty acid composition of liver phospholipids the typical pattern of EFA deficiency, increased 18:1 and 20:3 omega 9 and decreased 18:2 and 20:4. It is evident from the current investigation that partial deprivation of protein during early development may impair the conversion of linoleate to arachidonate in the rat and that the lack of arachidonic acid observed in the liver cells during protein deficiency would be the consequence of this impairment.
65 citations
TL;DR: By the end of the gonad development, a considerable increase of gonadal lipids and polyenoic fatty acids of 20 and 22 carbons was observed, and sexual maturation modified the lipid composition of gametes.
61 citations
TL;DR: It was concluded that nutritional factors can modify a taxonomic distance in three different ways: evoking morphological differences among populations of the same racial group, altering differences among racial groups, and modifying the pattern of sexual dimorphism of a population.
Abstract: Wistar and Holtzman rats were fed (a) control diet ad libitum (controls); (b) restricted control diet (undernourished); and (c) low-protein diet ad libitum (malnourished), from weaning to 70 days of age. Mahalanobis D2 distances between cranial groups were assessed. Besides, differences among traits were assessed by the analysis of variance and Tukey test. The relative influence of each factor yielded a decreasing sequence: protein-calorie malnutrition (PCM)-Protein deficit (PD)-race-sex. However, this sequence differed between races. The significant sexual dimorphism in Wistar controls disappeared because of PCM and PD. Race and sex, race and nutrition, and race, sex, and nutrition interacted. Traits were classified into: (a) specific, (b) nonspecific, and (c) invariable. The specific race traits were alveolar length and foraminal width. The specific nutritional traits were neurocranial and splanchnocranial lengths and heights, alveolar and neurocranial widths, and the neuro-splanchnorcranial index (NSI) and the neurocranial vertico-transversal index (NVTI). There were no specific sexual traits. It was concluded that nutritional factors can modify a taxonomic distance in three different ways: (a) evoking morphological differences among populations of the same racial group, (b) altering differences among racial groups, and (c) modifying the pattern of sexual dimorphism of a population. It is suggested that craniological studies should take into account only the set of specific traits, disregarding both specific traits due to other factors and nonspecific ones.
44 citations
TL;DR: Since birds lack the pars intermedia of the pituitary gland, the presence of ACTH-, α-MSH-, and β-MSh-containing cells in the pars distalis of the duck was investigated and the coexistence of α- MSH and ACTH in all cells containing either of the two hormones could be established.
35 citations
TL;DR: In this paper, the authors investigated the effect of interfacial adsorption on the gas chromatographic retention behavior of lower aromatic hydrocarbons using glycols as stationary phases.
24 citations
TL;DR: In this paper, the reaction of NH3 with the pentacyanonitrosylferrate(II) ion has been studied spectrophotometrically at different pH values and concentrations of base.
23 citations
TL;DR: The extraction of vanadium(V) from HCl solutions into pure and CCl4 solutions of TBP (tri-n-butylphosphate) has been studied as a function of acid and TBP concentrations as mentioned in this paper.
22 citations
TL;DR: Fasting produced a decrease of the amount of ethanolamine fraction in HTC cells together with a significant increase in the specific activity of the same fraction and modified the fatty acid composition of HTC cells and rat liver microsomes.
Abstract: The effect of fasting on Δ5 desaturation activity in Minimal Deviation Hepatoma 7288c (HTC) cells and in rat liver microsomes was studied. When HTC cells were incubated in the absence of carbon sources in the medium (fasted cells) the conversion of [1-14C] eicosa-8,11,14-trienoic acid to arachidonic acid increased significantly compared to those cells incubated in complete medium (fed cells). This effect was also shown in rat liver microsomes of rats fasted for 12, 24 and 48 hr. Fasting produced a decrease of the amount of ethanolamine fraction in HTC cells together with a significant increase in the specific activity of the same fraction. Fasting also modified the fatty acid composition of HTC cells and rat liver microsomes. There was observed a relative increase of 18:2ω6 acid. The importance of the difference in fatty acid and lipid composition among fasted and fed HTC cells and rat liver microsomes on Δ5 desaturation activity was discussed.
16 citations
Journal Article•
16 citations
TL;DR: A single intraperitoneal (ip) injection of α-methyl-p -tyrosine (400 μg/g body wt) produced an intense and long-lasting darkening response in animals adapted to a white illuminated background as discussed by the authors.
TL;DR: The introduction of negative turns by DNA gyrase seems to make early genes unavailable for transcription, which could be taken as an indication that the appropriate secondary structure of the parental phage DNA is a requisite for the recognition of promoters.
TL;DR: In this article, the constrained Hartree-Fock approach of Elliott and Evans is studied in detail with reference to two quasi-spin models, and their predictions compared with those arising from a projection method.
TL;DR: The infrared spectra of orthoarsenates with apatite structure, of the formulaM5(AsO4)3X (M=Ca, Sr, Ba, Pb andX=F, Cl,Br) are measured and interpreted on the basis of a site-symmetry analysis as mentioned in this paper.
Abstract: The infrared spectra of orthoarsenates with apatite structure, of the formulaM5(AsO4)3X (M=Ca, Sr, Ba, Pb andX=F, Cl,Br) are measured and interpreted on the basis of a site-symmetry analysis. The influence of the different cations on the internal vibrations of the AsO34-ions is discussed.
TL;DR: It is suggested that increased cGMP levels interfere with cAMP and cAMP-dependent protein kinase in the mechanical effects of cyclic nucleotide phosphodiesterase inhibitors.
TL;DR: The results presented here strengthen the view that 5-HT is a natural releasing factor in Anolis, and indicate that this effect is exerted directly on the glandular cells of the NIL.
TL;DR: The effect of epinephrine on Δ5-desaturation activity was postulated to be evoked through an increase of the intracellular concentration of cyclic AMP.
Abstract: The effect of epinephrine and dibutyryl cyclic AMP on the oxidative desaturation of [1-14C]-eicosatrienoic acid to arachidonic acid of rat liver microsomes has been studied. Epinephrine, at a dose of 1 mg/kg/body weight, produced a significant decrease on Δ5-desaturation activity 3 hr after the injection. This effect was maintained up to 12 hr and reached the control values 48 hr after the hormone administration. Dibutyryl cyclic AMP treatment for 24 hr (5 mg/8 hr/100 g body weight) also produced a significant decrease of the conversion of eicosatrienoic acid to arachidonic acid in rat liver microsomes. The effect of epinephrine on Δ5-desaturation activity was postulated to be evoked through an increase of the intracellular concentration of cyclic AMP.
Journal Article•
TL;DR: In this article, a detailed study on the calibration of vapour pressure osmometry (VPO) using thirteen polystyrenes in a range of molecular weights up to 50 000 as solutes and chloroform, dichloromethane, ethyl methyl ketone, cyclohexane, and acetone as solvents is carried out.
Abstract: A detailed study on the calibration of vapour pressure osmometry (VPO) using thirteen different samples (eight of them polystyrenes) in a range of molecular weights up to 50 000 as solutes and chloroform, dichloromethane, ethyl methyl ketone, cyclohexane, and acetone as solvents is carried out. The results show that contrary to the commonly used calibration equation M = K · (ΔV/c), the relationship between the measuring result (ΔV/C)c=0 and molecular weight M obeys a function of the type M = K · (ΔV/c) in which the exponent a differs from 1. For each of the above mentioned solvents the values of K and a are determined. The limits of applicability of VPO with respect to polymers are discussed in view of these terms and recent theoretical considerations.
TL;DR: In this paper, the infrared spectra of different phases of composition Cd X M 10−X (PO 4 ) 6 X 2 structurally related to calcium fluoroapatite has been investigated and the distortive effects produced by the Cd(II) ion In these lattices discussed.
TL;DR: In this paper, the same method was applied to calculate the stability constants of the mixed ligands complexes of the system cadmium-acetate-propionate, and some theoretical, experimental and statistical aspects of the method applied to the mixed-ligands system have been discussed.
TL;DR: In this paper, the thermoelectric power and the resistivity of V2O5-TiO2 mixtures over ranges of composition and temperature from 20° to 500° in air have been measured, the mixtures were obtained by coprecipitation of aqueous solutions of NH4VO3 and TiCl4.
Abstract: The thermoelectric power and the resistivity of V2O5- TiO2 mixtures over ranges of composition and temperature from 20° to 500° in air have been measured, The mixtures were obtained by coprecipitation of aqueous solutions of NH4VO3 and TiCl4. calcined during 90 h at 550° and then sintered. Resistances were measured by the four points method. At the VO5/2 35–100% M range, the activation energies for conductivity change from 0,36 to 0.62eV, while for the thermoelectric power they change from 0,18 to 0.24eV. It can be assumed from these values that the conduction mechanism over this concentration range is due to the “hopping” of small polarons, arising principally, from the presence of V4+ ions. In the samples with a high TiO2 content, the activation energies for conductivity were 0.82 and 0.36eV, for the different samples. From the variation of thermoelectric power with temperature, it can be assumed that the ionization energy of the donors centers lies at 0.83eV under the conducting band. A mechanism for band conduction is inferred from the results, being the V4+ donating centers and the V5+ receptive centers.
TL;DR: Perfusion of the isolated rat heart at constant heart rate and coronary flow with the inhibitor of cyclic nucleotide phosphodiesterase, pentoxifylline, produced no significant effect on the maximum rate and the peak of contraction, but increased themaximum rate of relaxation.
Abstract: Perfusion of the isolated rat heart at constant heart rate and coronary flow with the inhibitor of cyclic nucleotide phosphodiesterase, pentoxifylline (10(-4) moles/l), produced no significant effect on the maximum rate and the peak of contraction, but increased the maximum rate of relaxation. cAMP level and cAMP-dependent protein kinase activity were increased in the absence of changes in cGMP. The results were identical in hearts of reserpinized rats.
TL;DR: It is concluded that the bulk of melanotrophic activity of the duck pituitary corresponds to a peptide which behaves as α-MSH in the analytical systems used.
TL;DR: Theorem 3.7 as mentioned in this paper shows that any q-dimensional algebraic cycle of X, 0 < q < n, is the analytic residue of a semimeromorphic (n-q)-form on X, having poles in the union of a family of complex hypersurfaces in X such that N ~ contains the support of ~.
Abstract: According to a classical result of Weil [15,1, a divisor ~ of a smooth n-dimensional projective variety X is homologous to zero if and only if it is the residue of a closed meromorphic 1-form on X. Griffiths proved recently [9, pp. 3-8,1 that a 0-cycle ~t of X is homologous to zero if and onty if it is the Grothendieck residue of a meromorphic n-form & on X having poles in the union of a family of complex hypersurfaces Yl . . . . . II, of X, such that (~ Y~ is 0-dimensional and contains the support of ~. We show in this paper (Theorem 3.7) that, in fact, any q-dimensional algebraic cycle ~ of X, 0< q < n, is the analytic residue of a semimeromorphic (n-q)-form on X, having poles in the union of a family ~ = {Y1 . . . . . Yn-q} of hypersurfaces in X such that N ~ contains the support of ~. The form & is not closed, in general, but its differential verifies
TL;DR: In this paper, the microwave spectrum of normal thiomorpholine (CH 2 ) was investigated within the region 8-40 GHz, and that of N -deuterothiomorphic (ND) within the range 26.5 -40 GHz.
TL;DR: In this paper, the extraction of Ti(IV) from aqueous sulphuric acid solutions using TBP (tri- n -butylphosphate) undiluted and in carbon tetrachloride solution has been studied.
TL;DR: In this paper, the deviation of MVPO from the true number average molecular weight Mn is estimated from its dependence on the polydispersity and the exponent a of the calibration function.
Abstract: Provided that in molecular weight determinations by vapor pressure osmometry (VPO) the relationship between M and the measured quantity (δV/c)c=0 obeys a calibration function of the type (δV/c)c=0 = KM−a, the kind of molecular weight average MVPO delivered by this method is derived. The deviation of MVPO from the true number average molecular weight Mn is estimated from its dependence on the polydispersity and the exponent a of the calibration function.