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A scanning densitometry-based method was used to determine absolute surface concentrations and homogeneity of a spray-coating treatment with a model dye, 5,8-dihydroxy-[1,4]-naphthoquinone (DHNQ), on hardwood veneers (Beech, Fagus sylvatica; Birch, Betula pendula; Oak, Quercus alba). An automatic TLC sampler sprayed accurately known amounts of several concentrations of DHNQ as rectangles on the surface. Scanning was then used to acquire the color intensities of each rectangle. After an adequate data treatment, three models – Michaelis-Menten and two logarithmic – were selected to fit the obtained intensities to the deposited surface concentrations. Based on the quality of fit and the residuals, the logarithmic model is examined in detail in this work. The method was validated by comparing expected concentrations to back-calculated ones, and produced correct results with acceptable error within ±20%. The applicability of the method was shown by a sprayed specimen. By comparing our method to two widely applied techniques, CIELAB color system and x-ray fluorescence, we demonstrated that densitometry is advantageous as it measures an absolute surface concentration, also of coatings containing atoms lighter than silicon. In production, densitometry can be adapted from current technologies and would quickly control the quality of the coated wood, or any other surface, with good sensitivity.

The present work aimed to treat a polyethylene terephthalate (PET) surface to make the biomaterial more 'attractive' in terms of attachment and shear stress response to endothelial cells with a view to possible applications in vascular grafting. A surface wet-chemistry protocol was applied to graft track-etched PET membranes with RGD peptidomimetics based on the tyrosine template and active at the nano-level vs. isolated human αvβ3 receptor, which was monitored by X-ray photoelectron spectroscopy, contact angle measurement and atomic force microscopy for characterization. A primary culture of human saphenous vein endothelial cells was used before and after sterilization of the membranes (heat treatment or γ-ray irradiation) to test the benefit of grafting. The optimal surface concentrations of grafted molecules were around 50 pmol/cm². Compared to GRGDS, the peptidomimetics promoted cell attachment with similar or slightly better performances. Endothelialized grafted supports were further exposed to 2 h of shear stress mimicking arterial conditions. Cells were lost on non-grafted PET whereas cells on grafted polymers sterilized by γ-ray irradiation withstood forces with no significant difference in focal contacts. At the mRNA level, cells on functionalized PET were able to respond to shear stress with NFkB upregulation. Thus, grafting of peptidomimetics as ligands of the αvβ3 integrin could be a relevant strategy to improve the adhesion of human endothelial cells and to obtain an efficient endothelialized PET for the surgery of small-diameter vascular prostheses.

This paper deals with the thermal degradation and fire performance of silicone-based coatings for protecting steel. In this study, the fire performance of silicone coatings as virgin or formulated materials is evaluated using two homemade fire testing methodologies: one similar to the “torch test” fire testing method and the other using a heat radiator test. It was shown that the performance of the silicone-based coating used as thermal barrier can be improved incorporating a modifier (a mixture of polydimethylsiloxane and silica coated by a silane). In this case, silicone-based coating swells and exhibits same fire performance as commercial intumescent coating at the torch test. It is shown that the incorporation of modifier in the silicone makes it to swell upon heating resulting in the formation of expanded material exhibiting low heat conductivity. Thermal degradation of the coating is also investigated: it occurs in three main steps leading to the formation of a tridimensional network characterized by the formation of Q4 structure at high temperature. Copyright © 2012 John Wiley & Sons, Ltd.

The surface of two commercial meltblown polypropylene (PP) membranes, used for the filtration of blood products, were modified by wet chemistry treatments (carbodiimide, tosyl chloride and trihalogeno-triazines) in the case of the oxygen-plasma treated membrane (O-2-PP), and by photochemistry using molecular clips in the case of the native PP membrane. The most efficient technique uses trifluoro-triazine reagent for the activation of both hydroxyl- and carboxyl-functions of O-2-PP. It enables the fixation of amine-terminated molecules with high degrees of derivatization (similar to 700 pmol/cm(2)), without inducing modification of the membrane morphology nor cytotoxicity. Only a weak decrease of surface hydrophilicity was measured after the treatments and steam-sterilization. This method was applied for the grafting of peptides (Gly-Gly-Gly-Gly-Gly, Gly-Arg-Gly-Asp-Ser, home-made modified Leu-Asp-Val) on O-2-PP membranes incorporated into multi-layer filter devices. These modified filters showed improved properties of leukocyte depletion in blood filtration experiments, principally due to the wetting properties of the membranes. (C) 2011 Elsevier Ltd. All rights reserved.

Ultrasmall particles of iron oxide (USPIOs) coated with 3,3'-bis(phosphonate)propionic acid were covalently coupled to a home-made Arg-Gly-Asp (RGD) peptidomimetic molecule via a short oligoethylene-glycol (OEG) spacer. The conjugation rate was measured by X-ray photoelectron spectroscopy (XPS). The particle size and magnetic characteristics were kept. Our novel conjugate targeted efficiently Jurkat cells (increase of 229% vs the control).

A two-step wet chemistry protocol has been developed for the surface derivatization of poly(ethylene terephthalate) (PET) track-etched membrane used as cell culturing support, that is, (a) activation by trifluorotriazine (1 M in acetonitrile (ACN), 30 degrees C, 3 h); (b) coupling to amine-terminated molecules, namely 3,5-bis(trifluoromethyl)benzylamine ((F)Tag), (L)-4,5-[H-3]-lysine, and Gly-Arg-Gly-Asp-Ser (GRGDS) pentapeptide (10(-3) M in PB-ACN, 1:1 (v/v), 20 degrees C, 17 h). The grafting rates determined by X-ray photoelectron spectroscopy, from the F/C and N/C atomic ratios, are in the range of 100-140 pmol/cm(2) (apparent surface), whereas the liquid scintillation counting assays give higher values (180-d230 pmol/cm(2)) corresponding to the open surface reactivity. PET-g-(F)Tag is reasonably stable under two usual sterilization conditions of biomaterials, that is, steam heating at 121 degrees C and gamma-irradiation at 25 kGy. On the other hand, PET-g-GRGDS is found to be stable only under ionization radiation (84% of remaining peptide molecules), but damaged in a large extent by the autoclave treatment (23% of remaining peptide molecules). The surfaces of the sterilized PET and PET-g-GRGDS samples have been characterized by water contact angle measurement and by atomic force microscopy analysis in air and under water. Comparatively to the corresponding nonsterilized surfaces, gamma-irradiated surfaces are slightly more hydrophilic and also slightly more rough and jagged. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 195-208, 2010

RGD peptides are used in biomaterials science for surface modifications with a view to elicit selective cellular responses. Our objective is to replace peptides by small peptidomimetics acting similarly. We designed novel molecules targeting alpha(v)beta(3) integrin and featuring spacer-arms (for surface grafting), which do not disturb the biological activity, from (l) N-(3-(trifluoromethyl)benzenesulfonyl) tyrosine used as scaffold. Various Arg-mimics were fixed on the phenol function, and the ortho position was used for the coupling of OEG spacers. All peptidomimetics were active in the nM range in a binding test toward human alpha(v)beta(3) integrin (IC(50) = 0.1 to 1.7 nM) and selective versus platelet integrin alpha(IIb)beta(3). Selected compounds revealed excellent ability to inhibit bone cells adhesion on vitronectin. Modeling and docking studies were performed for comparing the most active RGD peptidomimetic to cilengitide, i.e., cyclo-[RGDfN(Me)V]-. Lastly, the adhesion of endothelial cells on a cultivation support grafted with RGD peptidomimetics was significantly improved.

Fragile X syndrome (FXS), the most common cause of inherited intellectual disability and autistic spectrum disorder, is typically caused by transcriptional silencing of the X-linked FMR1 gene. Work in animal models has described altered synaptic plasticity, a result of the up-regulation of metabotropic glutamate receptor 5 (mGluR5)-mediated signaling, as a putative downstream effect. Post hoc analysis of a randomized, placebo-controlled, crossover phase 2 trial suggested that the selective mGluR5 antagonist mavoglurant improved behavioral symptoms in FXS patients with completely methylated FMR1 genes. We present the results of two phase 2b, multicenter, randomized, double-blind, placebo-controlled, parallel-group studies of mavoglurant in FXS, designed to confirm this result in adults (n = 175, aged 18 to 45 years) and adolescents (n = 139, aged 12 to 17 years). In both trials, participants were stratified by methylation status and randomized to receive mavoglurant (25, 50, or 100 mg twice daily) or placebo over 12 weeks. Neither of the studies achieved the primary efficacy end point of improvement on behavioral symptoms measured by the Aberrant Behavior Checklist-Community Edition using the FXS-specific algorithm (ABC-C(FX)) after 12 weeks of treatment with mavoglurant. The safety and tolerability profile of mavoglurant was as previously described, with few adverse events. Therefore, under the conditions of our study, we could not confirm the mGluR theory of FXS nor the ability of the methylation state of the FMR1 promoter to predict mavoglurant efficacy. Preclinical results suggest that future clinical trials might profitably explore initiating treatment in a younger population with longer treatment duration and longer placebo run-ins and identifying new markers to better assess behavioral and cognitive benefits.

ISBN 3-8055-3546-5

Crystal and molecular structures of hexachlorobenzene C6Cl6 were investigated by molecular-packing analysis with a computed dynamical model. This model includes thermal motions and molecular deformations. Several crystalline structures with monoclinic symmetry P21/c have been found by the calculation. Factors which influence the stability of these structures are investigated. The lowest-energy structure, labeled I, agrees with the experimental one. Calculated crystal and molecular parameters agree with data determined by x-ray diffraction at 296 K. While no temperature-induced phase transition has been found from 296 to 124 K at ambient pressure, a phase transformation has been evidenced numerically at 0.43 GPa and 296 K. The monoclinic pressure-induced phase, stable above 0.43 GPa, is labeled II.

In order to study the influence of pancreatic enzyme secretion on the intestinal absorption of mediumchain fatty acids (MCFA), three growing pigs (mean body-weight 61 kg) with ligated and severed pancreatic ducts were fitted with a permanent fistula in the duodenum and with two catheters in the portal vein and carotid artery respectively. An electromagnetic flow probe was also set up around the portal vein. A mixture of octanoic and decanoic acids, esterified as medium-chain triacylglycerols, together with maltose dextrine and a nitrogenous fraction was continuously infused for 1 h into the duodenum. Samples of blood were withdrawn from the two vessels at regular intervals of time for 8 h and further analysed for their non-esterified octanoic and decanoic acid contents. The concentrations of non-esterified octanoic and decanoic acid in the portal blood increased slowly after the beginning of each infusion, reaching about 10 times higher values than the basal level. Only 26% of octanoic acid infused in the duodenum and 27% of decanoic acid were recovered in the portal flow throughout each experiment. The possible mechanisms underlying the appearance of MCFA in the portal blood in the absence of pancreatic enzyme secretions and the importance of duodenal absorption of MCT in such physiological conditions have been discussed.

The objectives of the study were to assess the 13C bicarbonate dilution technique using an automatic blood sampling system and to use this technique to estimate energy expenditure (EE) based on the CO2 production of 14 lactating Holstein cows on pasture or in a freestall barn. The effects of physical activity and eating behavior on EE were also assessed. Cows were exposed to each feeding system in a crossover design with two 14-d experimental periods, each consisting of an adaptation period and a 7-d data collection period. Cows either grazed on pasture or had ad libitum access, in the freestall barn, to grass cut daily from the same paddock. All cows were supplemented with a cereal-based concentrate. The EE of each cow was determined from 0700 to 1300 h on 1 d of each collection period. Blood samples for the 13C bicarbonate dilution technique were taken either manually in the barn or using an automatic blood sampling system on pasture. Eating pattern and physical activity were recorded from 0700 to 1300 h using a behavior recorder and an activity meter, respectively. Milk yield was recorded daily. Individual feed intake was estimated using the alkane double-indicator technique. Two preceding experiments confirmed that the sampling technique (manual or automatic) and the following storage of the blood samples (frozen directly after withdrawal or first cooled on ice and then frozen 6 h later) had no effect on 13CO2 enrichment in the extracted blood CO2 or on the subsequent calculation of CO2 production. During the 6-h measurement period, the EE of cows on pasture was higher than that of cows in the freestall barn. Daily feed intake and milk production were not affected by the feeding treatment. Grazing cows spent more time walking and less time standing and lying than did cows fed indoors. Time spent eating was greater and time spent ruminating was lower for cows on pasture compared with grass-fed cows in the barn. In conclusion, the 13C bicarbonate dilution technique, combined with an automatic blood sampling system, is a suitable method to determine the EE of lactating dairy cows on pasture. Positive correlations between EE and walking and eating time indicate that the higher energy requirements of dairy cows on pasture may be at least partly caused by a higher level of physical activity. However, before specific recommendations about additional energy supply can be given, it must be determined whether EE measured over 6 h can be extrapolated to 24 h. Furthermore, the apparent inconsistency between EE, feed intake, and milk production needs to be resolved.

A graftable LDV (Leu-Asp-Val) peptidomimetic molecule (B-c) has been prepared from 3-(5-amino-2-hydroxy)phenyl-propionic acid, as alpha(4)beta(1) (VLA-4) integrin ligand. For that purpose, the mechanism of 3-(4-azidophenyl)propionic acid rearrangement has been revisited. Activation of Durapore DVPP-hydrophilic membrane, by surface wet chemistry using triazine trifluoride, followed by covalent coupling of B-c produced a modified filter (0.8% of derivatisation from XPS analysis) with improved capacity of leukocyte retention.

The purpose of the present study was to determine the amount of cocaine and benzoylecgonine in the plasma of Aymara Indians from the Bolivian Andes after traditional chewing of coca leaves during exercise performance. The determination was carried out by high performance liquid chromatography after solid-liquid extraction. The results showed that such use of coca leaves is well correlated with pharmacologically active concentration of cocaine in plasma.

In order to study the rate of intestinal absorption and hepatic uptake of medium-chain fatty acids (MCFA), six growing pigs, mean body weight 65 kg, were fitted with a permanent fistula in the duodenum and with three catheters in the portal vein, carotid artery and hepatic vein respectively. Two electromagnetic flow probes were also set up, one around the portal vein and one around the hepatic artery. A mixture of octanoic and decanoic acids, esterified as medium-chain triacylglycerols, together with maltose dextrine and a nitrogenous fraction was continuously infused for 1 h into the duodenum. Samples of blood were withdrawn from the three vessels at regular intervals for 12 h and further analysed for their non-esterified octanoic and decanoic acid contents. The concentration of non-esterified octanoic and decanoic acids in the portal blood rose sharply after the beginning of each infusion and showed a biphasic time-course with two maximum values, one after 15 min and a later one between 75 and 90 min. Only 65 % of octanoic acid infused into the duodenum and 54 % of decanoic acid were recovered in the portal flow throughout each experiment. The amounts of non-esterified MCFA taken up per h by the liver were close to those absorbed from the gut via the portal vein within the same periods of time, showing that the liver is the main site of utilization of MCFA in pigs. These results have been discussed with a special emphasis laid on the possible mechanisms of the biphasic time-course of MCFA absorption and the incomplete recovery in the portal blood of the infused fatty acids.

Comparison is made between X-ray data and estimated secondary structures from amino acid sequence in using adapted predictive rules of Chou and Fasman (3, 4) and from circular dichroism.X-ray data revealed 6 % α helix, 45 % β sheet, 15 % β turns and 34 % aperiodic structure.The predictive scheine yielded 30 % α helix, 21 % β sheet, 28 % β turns and 21 % aperiodic structure. Only β sheet prediction was given with a confidence limit of 99 %.Circular dichroism from data of three laboratoires would yield 1 ± 10 % α helix, 43 ± 20 % β sheet and a very variable aperiodic structure content depending on the standards and methods of fitting used.

A 2.5 A resolution electron density map of human plasma prealbumin has been calculated using three isomorphous derivatives. Interpretation of the map shows that the molecule is a tetramer composed of identical subunits. Each subunit is composed of a single polypeptide chain containing between 124 and 128 residues, which is consistent with the tetramer molecular weight of 54,000. Half the residues in each monomer are organized into two extensive β-sheets each composed of four strands. All the strand interactions are antiparallel, with one exception. The remaining residues are involved in loops of various kinds that link the β-strands together, one of which contains a very short α-helix. The isolated monomer has the shape of a prolate ellipsoid, with the two β-sheets forming a large part of its surface. The monomers are linked into stable dimers by further antiparallel β-sheet interactions involving equivalent strands at the edge of each of the monomer's β-sheets. This gives the dimer two β-sheets each composed of eight strands, four of which derive from one monomer and four from the other. The dimers are assembled into the complete tetrameric molecule with equivalent β-sheets from each dimer opposed at the centre of the molecule. These β-sheets are kept at greater than contact distance by a short loop of chain from each monomer that forms the major dimer-dimer interaction. The opposed, but separated, β-sheets, form the surface of a large slot that runs through the centre of the molecule. Low-resolution X-ray analysis of the binding of thyroxine and tri-iodothyronine to prealbumin shows that the hormones are bound in two symmetry-related binding sites located deeply in the central slot.

1. An experiment was carried out on growing male rats to study the effects of a phosphorus deficiency on voluntary energy intake, estimated by the separate-feeding technique, as well as the consequences on growth and metabolic utilization of energy, protein and minerals. After a preliminary period of P deprivation, three groups of twelve animals were fed separately and simultaneously two dietary rations. A protein ration provided 1.2 g protein/d to which was added one of three levels of P in the form of monosodium phosphate: a normal level of 35.4 mg/d (treatment A), half the normal level (19.1 mg/d, treatment B) or one-quarter the normal level (9.6 mg/d, treatment C). Another protein-free ration was fedad lib.2. It was only when the level of P represented one quarter the normal level that a significant decrease in growth rate was noticed, accompanied by a definite decrease in daily energy consumption. The food conversion ratio (g dry matter intake/g body-weight gain) increased whereas the protein efficiency ratio (g body-weight gain/g protein intake) was lower. The nitrogen and energy retentions changed in the same way: both dectreased with treatment C compared to treatment A and B. Independently of the protein supply, the voluntary energy intake was closely related to the intensity of protein retention, which depended on the dietary level of P. The daily retention of P only slightly decreased at the lowest ingestion level (9.6 mg/d in treatment C), compared to that of the higher levels. On the other hand, the amount of calcium retained regularly decreased with the decreasing supply of P. The result of this was a progressive reduction in retained Ca:P as the level of P decreased.3. From these results it appeared that the primary effect of a P deficiency in the growing rat was a decrease in bone mineralization. At a more advanced stage, the tissue P levels were affected and the resulting metabolic alterations reduced protein deposition and consequently the voluntary energy intake. The level of energy consumption, in separate-feeding, is more generally dependent on the level of protein deposition allowed by the limiting factor for growth, either protein, minerals or vitamins.

In the present work, we determined the activity of voltage-dependent dihydropyridine (DHP)-sensitive Ca2+ channels related to PRL, GH, and LH secretion in primary cultures of pituitary cells from male or female rats. We investigated their modulation by 17 beta-estradiol (E2) and their involvement in dopamine (DA) and somatostatin (SRIF) inhibition of PRL and GH release. BAY-K-8644 (BAYK), a DHP agonist which increases the opening time of already activated channels, stimulated PRL and GH secretion in a dose-dependent manner. The effect was more pronounced on PRL than on GH release. BAYK-evoked hormone secretion was further amplified by simultaneous application of K+ (30 or 56 mM) to the cell cultures; in parallel, BAYK-induced 45Ca uptake by the cells was potentiated in the presence of depolarizing stimuli. In contrast, BAYK was unable to stimulate LH secretion from male pituitary cells, but it potentiated LHRH- as well as K+-induced LH release; it had only a weak effect on LH secretion from female cell cultures. Basal and BAYK-induced pituitary hormone release were blocked by the Ca2+ channel antagonist nitrendipine. Under no condition did BAYK affect the hydrolysis of phosphoinositides or cAMP formation. Pretreatment of female pituitary cell cultures with E2 (10(-9) M) for 72 h enhanced LH and PRL responses to BAYK, but was ineffective on GH secretion. DA (10(-7) M) inhibited basal and BAYK-induced PRL release from male or female pituitary cells treated or not treated with E2 (10(-9) M). SRIF (10(-9) and 10(-8) M) reversed BAYK-evoked GH release to the same extent in cell cultures derived from male or female animals. It was ineffective on BAYK-induced PRL secretion in the absence of E2, but antagonized it after E2 pretreatment. The effect was dependent upon the time of steroid treatment and was specific, since 17 alpha-estradiol was inactive. In addition, DA and SRIF decreased the 45Ca uptake induced by the calcium agonist. These data demonstrate that DHP-sensitive voltage-dependent calcium channels of the L type present on different pituitary cells are not equally susceptible to BAYK activation under steady state basal conditions, indicating that their spontaneous activity and/or distribution vary according to the cell type; their activity is modulated by sex steroids. In addition, these data suggest that Ca2+ channels represent a possible site of DA and SRIF inhibition of PRL and GH release, respectively, by gating calcium entry into the corresponding cells.

The principal elements of the secondary, tertiary and quaternary structure of the tetrameric human plasma prealbumin molecule have been determined by Fourier refinement of X-ray diffraction data at 1.8 A resolution. The subunit has an extensive β-structure composed of eight strands organised into two four-stranded sheets. There is also one short α-helix. The tertiary structure is largely determined by the association of the two β-sheets. Important contributions to the tertiary structure are made by three tyrosines and one aspartic acid involved in side-chain-main-chain interactions; a buried histidine associated with a group of internal water molecules; and a compact cluster of seven aromatic residues. Quaternary interactions occur at two sets of interfaces closely organised around two of the three molecular 2-fold axes. The exclusive monomer-monomer interface is chiefly concerned with antiparallel hydrogen bond interactions which extend the two four-stranded sheets in the monomers to eight-stranded sheets in the dimer. One of the sheet interactions includes water molecules and tyrosine hydroxyls in the hydrogen bond pattern. The dimers associate through both hydrophilic and hydrophobic interactions at interfaces that involve all four monomers.

Lobster muscle arginine kinase crystals have been grown by a procedure of gaseous diffusion. The resulting crystals are monoclinic. space group P21 with unit cell dimensions of a = 75.9 A , b = 88.3 A , c = 58.2 A , β = 102.0 ° . Considerations of cell volume and protein molecular weight indicated the presence of two molecules in the asymmetric unit. A search for heavy-atom derivatives is in progress.

Prealbumin is a plasma protein which, in conjunction with another protein, is responsible for the plasma transport of vitamin A. X-ray examination of prealbumin crystals has shown that the protein crystallizes in the orthorhombic system but with such a high degree of pseudo body-centring that the real space group is concealed. This has been found to be a consequence of molecular symmetry in the prealbumin molecule. Examination of the pseudosymmetry in terms of models of the protein molecule has permitted the quaternary structure of prealbumin and the real space group to be defined. The prealbumin molecule appears to be a tetramer with a molecular weight of 54,000 ± 5000, composed of identical or nearly identical subunits arranged tetrahedrally.

ISBN 3-8055-3546-5

The kinetics of appearance of various nutrients in the portal vein during the postprandial period was studied in conscious pigs by means of a technique based on measurement of the porto-arterial differences in nutrient concentrations simultaneously with that of the portal blood flow rate. The rate and level of appearance of sugars in the portal vein varied with the carbohydrate ingested. It was very rapid after intake of glucose and sucrose, slower after that of maize starch and very slow after that of lactose. The absorption of the latter became very rapid again if it was hydrolysed prior to its ingestion. During absorption, some sugars (fructose or galactose) released from the corresponding sucrose and lactose, respectively during digestion, were partly metabolized into glucose by the enterocyte. The rate of absorption of amino acids released in the digestive tract varied according to the origin of the food ingested, i.e. it was more rapid after intake of wheat or fish proteins than after that of barley. In the case of barley the absorption rate of amino acids differed from that of glucose of the starch. The profile of the amino acid mixtures appearing in the portal vein during absorption differed a little from the profiles of those present in the ingested proteins in the case of essential amino acids and differed much in the case of non essential amino acids. Some essential amino acids (histidine, aromatic amino acids) appeared more rapidly and others more slowly, (lysine, sulphur amino acids, arginine). Because of transaminations, only small amounts of glutamic acid occurred in the portal vein whereas the amounts of alanine as compared to those ingested, were very large. The hierarchy of amino acid absorption was the same whatever the protein studied (fish, wheat, barley). The appearance in the portal vein of alpha-amino nitrogen from enzyme hydrolysates perfused through the duodenum was more rapid than after perfusion of a mixture of free amino acids. During digestion of diets containing 6% cellulose, large amounts of volatile fatty acids (about 2200 mmol/24 h, i.e. 2500 kJ/24h) and lactic acid (60-85 g/24 h) appeared in the portal vein.

We previously demonstrated a specific stimulatory action of estrogens on phosphatidylethanolamine methylation in rat pituitary membranes. To investigate the physiological relevancy of this effect, the activity of methylating enzyme(s) was evaluated during the rat estrous cycle, a period in which both endogenous ovarian steroid levels and the sensitivity of pituitary membrane receptors fluctuate. Anterior pituitary membranes (P2) were prepared from adult female rats at different stages of the estrous cycle and assayed for phospholipid methylation in the presence of S-adenosyl-[methyl-3H]methionine as a donor of 3H-methyl groups. Methylated phospholipids were separated by TLC. Formation of phosphatidyl-mono- and dimethylethanolamine and that of phosphatidylcholine increased significantly in the morning, reaching maximal values on the afternoon of proestrus; they decreased thereafter during estrus, metestrus, and diestrus. Plasma estradiol concentrations increased in late diestrus and then varied similarly with the fluctuations of phospholipid methyltransferase activity throughout the cycle. In parallel, plasma levels of LH and PRL were significantly elevated during the afternoon of proestrus, but remained low throughout the rest of the cycle. Under the same experimental conditions, phospholipid methylation in membranes prepared from mediobasal-hypothalamic structures was not affected. These data demonstrate that under physiological conditions the increased pituitary methyltransferase activity is associated with the progressive increment of plasma estradiol levels occurring shortly before proestrus and precedes the release of LH and PRL. Ovariectomy significantly decreased methyltransferase activity; however, 17 beta-estradiol treatment of ovariectomized rats for 5 days restored the enzyme activity, which was further augmented after progesterone administration. Attempting to investigate variations of pituitary methyltransferase activity in male rats, we demonstrated that the intact males showed weaker activity than that of females; orchidectomy diminished the phospholipid methylation, but adrenalectomy had no effect.

(1986). Recycling of Endogenous Nitrogen in the Pig (Preliminary Results of a Collaborative Study) Archiv fur Tierernaehrung: Vol. 36, No. 2-3, pp. 269-274.

cited By 1; International audience; Solid [CuI(piperazine)0.5]∞, characterized by a structure with an infinite double chain of CuI, presents an unexpected dual luminescence. The short copper-copper distances allow the existence of both cluster-centered and 1-D delocalized electronic transitions, as emerged from theoretical calculations. Beyond the more common cluster-centered emission a higher energy band, which differs in lifetime and in temperature dependence, is observed. © The Royal Society of Chemistry 2015.

cited By 48; International audience; We present the results of a first principles study on the ordered Ge 0. 50C 0.50 and Sn 0.50C 0.50 cubic alloys. A linear combination of atomic orbitals approach in the framework of density functional theory is employed for total energy calculations in the zincblende phase. A fitting of the energy surface to the equation of state yields the lattice constant of 4.61 and 5.17 Å and the bulk modulus of 181 and 119 GPa for GeC and SnC, respectively. Analysis of band structure suggests a crossover of the nature of the band gap from indirect to direct in going from SiC to GeC to SnC. Although both alloys predicted to be unstable with respect to their elemental components at zero pressure and temperature, GeC appears to become stable at higher pressure. It appears that both the lattice constant and bulk modulus of the ordered alloys do not follow Végard's linear rule, though the calculated dielectric constant of the cubic alloys is approximately the average of the dielectric constant of their elemental components.