oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Plasma Levels of Amino Acids in Japanese Men and Their Changes after the Administration of Glucose and Sucrose  [PDF]
Akikazu Takada, Fumiko Shimizu, Yukie Ishii, Mutsumi Ogawa, Tetsuya Takao
Food and Nutrition Sciences (FNS) , 2019, DOI: 10.4236/fns.2019.101005
Abstract: Background: It is not known whether plasma amino acids levels are different between young and old men in Japan. No research has been reported about changes in plasma levels of amino acids after the administration of glucose or sucrose to young and aged men. Objective: We want to know whether there are age differences in plasma levels of amino acids and if the administration of glucose or sucrose influences their levels. Results: Old people had lower plasma levels of most of amino acids, especially essential and branched-chain amino acids than young men. Plasma levels of amino acids were measured after the administration of 50 grams of glucose or sucrose to young (18 - 22 years old) and aged (≥50 years old) male adults. Plasma levels of total amino acids decreased after the administration of glucose. Decrease in the total amino acid levels was significant in aged men after the administration of sucrose. A significant decrease in plasma levels of total non-essential amino acids was observed at 120 min after the administration of glucose but not sucrose in both aged and young men. Both glucose and sucrose administrations resulted in a significant decrease in the plasma levels of the total essential amino acid levels and branched amino acids in young and aged men. Conclusion: These results suggest that there are age differences in plasma levels of amino acids. Upon the administration of glucose or sucrose amino acids, particularly essential amino acids, decreased in plasma. These amino acids may be transported from the blood soon after the administration of sugar (glucose or sucrose) to the tissues, such as muscles, possibly due to an increase in the insulin levels.
Volumetric, viscometric and refractive index behaviour of amino acids in aqueous glycerol at different temperatures
A. ALI,S. KHAN,F. NABI
Journal of the Serbian Chemical Society , 2007,
Abstract: Densities, ρ, viscosities, η, and refractive indices, nD, of solutions of some amino acids (glycine, DL–alanine, DL–α–amino–n–butyric acid, L valine and L leucine) in the concentration range 0.02 to 0.10 m in 5 % (v/v) aqueous glycerol were determined at 298.15, 303.15, 308.15 and 313.15 K. These experimental data were used to calculate the apparent molar volumes, Φν, the infinite dilution apparent molar volumes, Φν0, the partial molar volumes of transfer, Φν0 (tr), of the amino acids from aqueous to aqueous glycerol solution, as well as the viscosity A and B coefficients of the Jones–Dole equation of the amino acids. The free energies of activation of viscous flow, Δμ10# and Δμ20# per mole of solvent and solute, respectively, were obtained by application of the transition–state theory to the B coefficient data and the corresponding activation enthalpy, ΔH*, and entropy, ΔS*, were also determined. The Φν0, B coefficients and Δμ20# were found to vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from the zwitterionic end groups (NH3+, COO-) and methylene (CH2) groups of the amino acids. The experimental values of the refractive indices, nD, were used to calculate the molar refractive indices, RD, of the amino acids + aqueous glycerol ternary mixtures. The results were interpreted in the light of the solute–solvent and solute–solute interactions in the mixed solvents.
Effects of the Biomolecules: Vitamins, Proteins, Amino Acids, and Surfactants: DTAB, MTOAC, TMSOI, Orcinol on Upper Critical Solution Temperatures  [cached]
Man Singh,Vinod Kumar
International Journal of Thermodynamics , 2007, DOI: 10.5541/ijot.196
Abstract: Upper critical solution temperatures (UCSTS ± 0.05 K) and mutual solubilities of phenol + water systems are reported separately with 0.5 millimol kg-1 (mm kg-1) proteins (casein, pepsin, egg-albumin), vitamins (B1-thiamine, B2-riboflavin, B6-pyridoxine), amino acids (glycine, β-alanine, L-leucine) and surfactants (dodecyl trimethylammonium bromide- DTAB, trimethylsulphoxonium iodide-TMSOI, methyltrioctylammonium chloride- MTOAC, orcinol). The additives decrease the UCSTs by about 0.50-2 0C with slight enhancement in mutual solubilities but the leucine with two –CH3 (methyl) and two - CH2- (methylene) groups produce negligible increase in the solubilities. The –CH3 and - CH2- groups develop stronger hydrophobic interactions but the glycine develops stronger hydrophilic interactions due to –N+H3 (amino) and –COO- (carboxylic) groups and weaker hydrophobic due to single –CH2- group. The leucine increases the solubility by 0.009 mole fractions with a 0.7 0C decrease in USCT as compared to phenol-water. The mole fractions of additives restricted to 0.002 to 0.005 range, the conjugations of casein and vitamins in place of –CH3 groups of amino acids enhance the solubility with lower UCST values.
Examination of the Composition of the Luminal Fluid in the Small Intestine of Broilers and Absorption of Amino Acids under Various Ambient Temperatures Measured In vivo  [PDF]
A. Lemme,M.A. Mitchell
International Journal of Poultry Science , 2008,
Abstract: Composition and normal concentrations of nutrients (glucose, methionine, sodium and potassium) as well as the pH and osmolarity were determined in digesta collected from different segments of the small intestine of broilers both under thermoneutral and heat stress conditions in order to formulate a perfusate closely simulating physiologically normal conditions of the small intestine. Whilst glucose and methionine levels of the luminal fluid decreased with passage (p<0.05) sodium and potassium increased (p<0.05). Heat stress (30°C) partly decreased concentrations of glucose and methionine in digesta (p<0.05). Based on these analyses, a luminal perfusate was composed and used to study the absorption of DL-methionine (DL-Met) and the liquid hydroxy analogue of methionine (DL-HMB) as well as of the DL-HMB di-and oligomers under different ambient temperature conditions in vivo. Adaptive responses on length and weight of small intestine (jejunum) as well as on absorption of both methionine sources were observed which were dependent on the magnitude of imposed heat load. At higher temperature (35°C) length and weight of the small intestine decreased while absorption rate of both Met sources increased compared to the thermoneutral condition (22°C). Data suggested higher absorption velocity for DL-Met compared to that for DL-HMB (p>0.05). There was no interaction between DL-Met and DL-HMB absorption and ambient temperature. It was demonstrated that only a marginal portion of the di-and oligomer fraction of DL-HMB was absorbed. Results suggest that the perfusate formulated on basis of luminal fluid analyses was suitable for investigating absorption of amino acids.
Structure-making and Breaking Behaviour of Some a-amino Acids in Aqueous Sodium Butyrate Medium at 298.15K  [PDF]
S. Thirumaran,K. Job Sabu
Journal of Applied Sciences , 2011,
Abstract: The present study aims for the structure-making and structure-breaking behaviour of some amino acids in aqueous sodium butyrate solution at 298.15 K. The present investigation exploring the possible molecular interactions between the amino acids and organic salts such as sodium butyrate, which is known to have much dissociation of proteins in the solvent mixture. Experimental values of density, viscosity and ultrasonic velocities were carried out on the ternary mixtures of water+sodium butyrate+amino acids namely (L-asparagine, L-glutamine, L-serine and L-threonine) at 298.15 K. The present study was carried out by varying the different mass percentages of binary mixtures (water+sodium butyrate) varying from pure water to 20% (0, 5, 10, 15 and 20%) in increments of 5%. The related and relevant parameters correlated to our present study such as adiabatic compressibility (), molar hydration number (nH), apparent molar compressibility (fK), apparent molar volume (fV), limiting apparent molar compressibility (fk), limiting apparent molar volume (fv) and their associated constants (SK, SV), transfer volume (?fv) from water to aqueous solution viscosity B-Coefficient of Jones-Dole equations were meticulously evaluated. The molecular associations such as ion-ion, ion-solvent, solute-solvent, solute-solute etc are identified and critically discussed in terms of the structure-making and structure-breaking behaviour of amino acids in the solvent mixture.
Comparison of Sugars, Iridoid Glycosides and Amino Acids in Nectar and Phloem Sap of Maurandya barclayana, Lophospermum erubescens, and Brassica napus  [PDF]
Gertrud Lohaus, Michael Schwerdtfeger
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087689
Abstract: Background Floral nectar contains sugars and amino acids to attract pollinators. In addition, nectar also contains different secondary compounds, but little is understood about their origin or function. Does nectar composition reflect phloem composition, or is nectar synthesized and/or modified in nectaries? Studies where both, the nectar as well as the phloem sap taken from the same plant species were analyzed in parallel are rare. Therefore, phloem sap and nectar from different plant species (Maurandya barclayana, Lophospermum erubescens, and Brassica napus) were compared. Methodology and Principal Findings Nectar was collected with microcapillary tubes and phloem sap with the laser-aphid-stylet technique. The nectar of all three plant species contained high amounts of sugars with different percentages of glucose, fructose, and sucrose, whereas phloem sap sugars consisted almost exclusively of sucrose. One possible reason for this could be the activity of invertases in the nectaries. The total concentration of amino acids was much lower in nectars than in phloem sap, indicating selective retention of nitrogenous solutes during nectar formation. Nectar amino acid concentrations were negatively correlated with the nectar volumes per flower of the different plant species. Both members of the tribe Antirrhineae (Plantaginaceae) M. barclayana and L. erubescens synthesized the iridoid glycoside antirrhinoside. High amounts of antirrhinoside were found in the phloem sap and lower amounts in the nectar of both plant species. Conclusions/Significance The parallel analyses of nectar and phloem sap have shown that all metabolites which were found in nectar were also detectable in phloem sap with the exception of hexoses. Otherwise, the composition of both aqueous solutions was not the same. The concentration of several metabolites was lower in nectar than in phloem sap indicating selective retention of some metabolites. Furthermore, the existence of antirrhinoside in nectar could be based on passive secretion from the phloem.
Amino acids in retinitis pigmentosa  [cached]
Singh M
Indian Journal of Ophthalmology , 1988,
Abstract: Retinitis pigmentosa may be associated with amino acid′ disorders; whether the association is incidental or consequential is not known. The present investigation on amino acids in retinitis pigmentosa indicates that the level of plasma amino acids does not differ significantly in pa-tients with retinitis pigmentosa compared to that of normal subjects, hence it has no etiological bearing.
Amino acids in Arctic aerosols
E. Scalabrin, R. Zangrando, E. Barbaro, N. M. Kehrwald, J. Gabrieli, C. Barbante,A. Gambaro
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2012,
Abstract: Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids and quantify compounds at fmol m 3 levels. Mean total FAA concentration was 1070 fmol m 3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45–60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m 3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (< 0.49 μm) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanic emissions.
The Measurement of Sucrose Content of Sugar Cane Using Ultrasonic Waves
Amoranto Trisnobudi, Tjia Liong Hoei, Enung Rosihan Nugraha
Jurnal Teknologi dan Industri Pangan , 2001,
Abstract: The measurement of sucrose content of sugar cane is usually carried out by using polarimeter and Brix Wager scale. These two apparatus are operated manually so that the accuracy of the measurement results is depended on the operator skill. To overcome this problem we have developed an alternative method that can measure the sucrose content more quickly and accurately than the conventional methods. This new method was carried out by using ultrasonic waves whose velocity depends on the sucrose content. Firstly, the electronic apparatus used was calibrated with 37 samples of sugar cane with various sucrose content from 4.46 % to 7.29 %. The result of this calibration was an empirical equation between the ultrasonic wave velocity V and the sucrose content R, i.e. R = 2.65 V2 - 11,95 V + 17,65 where R in % and V in km/s. Then this equation was stored as database in a computer program that will be used to calculate the sucrose content. Finally, this sucrose content measurement system was tested by using 30 samples of sugar cane. The maximum error of the measurement result was 6.4 %.
Supernovae and the Chirality of the Amino Acids  [PDF]
R. N. Boyd,T. Kajino,T. Onaka
Physics , 2010, DOI: 10.1089/ast.2009.0427
Abstract: A mechanism for creating amino acid enantiomerism that always selects the same global chirality is identified, and subsequent chemical replication and galactic mixing that would populate the galaxy with the predominant species is described. This involves: (1) the spin of the 14N in the amino acids, or in precursor molecules from which amino acids might be formed, coupling to the chirality of the molecules; 2) the neutrinos emitted from the supernova, together with magnetic field from the nascent neutron star or black hole formed from the supernova selectively destroying one orientation of the 14N, and thus selecting the chirality associated with the other 14N orientation; (3) chemical evolution, by which the molecules replicate and evolve to more complex forms of a single chirality on a relatively short timescale; and (4) galactic mixing on a longer timescale mixing the selected molecules throughout the galaxy.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.