scholarly journals Arachidonate cannot be released directly from diacyl-sn-glycero-3-phosphocholine in thrombin-stimulated platelets

1989 ◽  
Vol 259 (2) ◽  
pp. 333-339 ◽  
Author(s):  
O Colard ◽  
M Breton ◽  
D Pepin ◽  
F Chevy ◽  
G Bereziat ◽  
...  
Keyword(s):  
Specific Activity ◽  
Head Group ◽  
Polar Head Group ◽  
Lipoxygenase Inhibitor ◽  
Phospholipid Molecular Species ◽  
Degree Of Unsaturation ◽  
The Mean ◽  
Specific Activities ◽  
Derivatives Of ◽  
Rat Platelets

The origin of the arachidonate released from platelets on stimulation with thrombin was investigated by comparing the specific activities of released arachidonate and of arachidonoyl-containing phospholipids using rat platelets prelabelled with arachidonate. Quantification of the released arachidonate was determined in the presence of BW 755 C, a dual cyclo-oxygenase/lipoxygenase inhibitor, which was found not to modify the arachidonate mobilization between the platelet phospholipids. The phospholipid molecular species were analysed by h.p.l.c. of diradylglycerol benzoate derivatives of diacyl, alkylacyl and alkenylacyl classes. The labelled/unlabelled arachidonate ratio varied greatly in the phospholipids depending on whether an ether or acyl bond was present in sn-1 position of the glycerol, on the length and degree of unsaturation of this fatty chain and on the polar head group. Between 15 s and 5 min of stimulation by thrombin, the released arachidonate kept a constant specific activity which was considerably lower than the specific activity of diacyl-GPC. The specific activity of the released arachidonate was intermediate between the specific activities of the 16:0-20:4 and 18:0-20:4 species of diacyl-GPI and diacyl-GPE, and corresponded to the mean specific activity of alkylacyl-GPC. The data indicate that the released arachidonate cannot come directly from diacyl-GPC, and that two phospholipids in particular can act as direct precursors of the released arachidonate. These are (1) the alkylacyl-GPC and (2) the diacyl-GPE whose hydrolysis would induce an arachidonate transfer from diacyl-GPC.

scholarly journals Specific Activities of Natural Radionuclides and Annual Effective Dose Due to the Intake of Some Types of Children Powdered Milk Available in Baghdad Markets

2017 ◽  
Vol 14 (3) ◽  
pp. 619-624
Author(s):  
Baghdad Science Journal
Keyword(s):  
Effective Dose ◽  
Sodium Iodide ◽  
Specific Activity ◽  
Annual Effective Dose ◽  
Natural Radionuclides ◽  
Mean Value ◽  
Powdered Milk ◽  
Effective Doses ◽  
The Mean ◽  
Specific Activities

In this research the specific activity of natural radionuclides 226Ra, 232Th and 40K were determined by sodium iodide enhanced by thallium NaI(TI) detector and assessed the annual effective dose in Dielac 1 and 2 and Nactalia 1 and 2 for children of less than 1 year which are available in Baghdad markets. The specific activity of 40K has the greater value in all the types which is in the range of allowed levels globally that suggested by UNSCEAR. The mean value of annual effective doses were 2.92, 4.005 and 1.6325 mSv/y for 226Ra, 232Th and 40K respectively.

scholarly journals Studies on mixed monolayers of phospholipids and fusogenic lipids

1975 ◽  
Vol 149 (3) ◽  
pp. 597-608 ◽  
Author(s):  
B Maggio ◽  
J A Lucy
Keyword(s):  
Specific Interaction ◽  
Erythrocyte Membranes ◽  
Head Group ◽  
Mixed Monolayers ◽  
Asymmetrical Distribution ◽  
Group 4 ◽  
Degree Of Unsaturation ◽  
Mixed Films ◽  
The Mean ◽  
Erythrocyte Lipids

1. The behaviour of mixed monolayers of 14 different lipids with preparations of erythrocyte lipids, purified natural and synthetic phospholipids, cholesterol and galactosylceramide was investigated. 2. The mean areas occupied per molecule in mixed films containing lipids that are fusogenic for hen erythrocytes were compared with those for corresponding films containing lipids that are inactive as fusogens. 3. Fusogenic lipids were found to exhibit interactions, which were not shown by non-fusogenic lipids, in mixed monolayers with several species of phospholipid, particularly those containing a choline head group. 4. Heterogeneity in the hydrophobic chains of phosphatidylcholine, their degree of unsaturation and the presence of cholesterol had little effect on the interaction of phosphatidylcholine with fusogenic lipids. 5. Fusogenic lipids showed little specific interaction with natural or synthetic preparations of phosphatidylethanolamine. 6. The possible significance of these observations in relation to the action of fusogenic lipids on biological membranes is discussed in the light of the asymmetrical distribution of phospholipids in erythrocyte membranes.

scholarly journals Transfer of Radiocesium into Wild Boar Meat

2010 ◽  
Vol 79 (9) ◽  
pp. S85-S91 ◽  
Author(s):  
Petr Dvořák ◽  
Petr Snášel ◽  
Katarína Beňová
Keyword(s):  
Wild Boar ◽  
Specific Activity ◽  
Natural Ecosystem ◽  
Fruiting Bodies ◽  
Mean Values ◽  
Main Emphasis ◽  
Wild Boar Meat ◽  
The Mean ◽  
Specific Activities ◽  
Remarkable Reduction

The aim of the study was to find the sources of 137Cs in wild boar food in the natural ecosystem. The main emphasis is focused on the analyses of wild boar muscles and the content of wild boar stomach. Boars weighing 20 to 100 kg were killed at two locations. The highest specific activities of muscles were measured in boars originated from the Dvorce location; the average specific activity in boars killed on 14 April 2007 and 9 March 2008 achieved 132 Bq kg-1. Due to high fluctuation the differences between the mean values of 31 Bq kg-1 in males and 43 Bq kg-1 in females were not significant. Earthworms from grass fields with a specific activity of 16 Bq kg-1, rootlets from the Šabrava location with 200 Bq kg-1 and Elaphomyces granulatus fruiting bodies with 4,743 Bq kg-1 and 2,858 Bq kg-1 are the components of boar food with the 137Cs specific activities higher than that of the detection limit. Consequently, underground mushrooms probably represent the main source of radiocesium in the food chain of boars. A remarkable reduction of 137Cs specific activities in boar muscles is not expected at the post-Chernobyl radiocesium contaminated locations with the occurrence of Elaphomyces granulatus within next two decades.

Distribution of Radioactive and Stable Zinc in an Experimental Marine Ecosystem

1971 ◽  
Vol 28 (11) ◽  
pp. 1783-1788 ◽  
Author(s):  
Ford A. Cross ◽  
James N. Willis ◽  
John P. Baptist
Keyword(s):  
Sea Water ◽  
Specific Activity ◽  
Marine Ecosystem ◽  
Water Concentration ◽  
Benthic Algae ◽  
Particulate Material ◽  
The Mean ◽  
Concentration Factors ◽  
Specific Activities ◽  
Extractable Zn

The distribution of radioactive and stable Zn in an experimental marine ecosystem is described. We added 1 mCi of 65Zn to 2000 liters of sea water and a mixed community of planktonic and benthic algae in a fiberglass tank, after which the ecosystem was left undisturbed for 9 months. We then measured the 65Zn specific activities for (1) particulate Zn (0.45 μ filterable), (2) extractable Zn (from water passed through a 0.45-μ filter and then treated with dithizone), (3) total dissolved Zn (from samples passed through a 0.45-μ filter and treated with acid prior to extraction with dithizone), and (4) dialyzable Zn. Zinc-65 specific activities were not significantly different among the extractable, dialyzable, or acid-treated samples of the water. Further, absolute concentrations of 65Zn and total Zn were no higher in the acid-treated samples than in the extracted or dialyzed samples, which indicates that nearly all of the soluble Zn in the water was dithizone-extractable and dialyzable. Zinc-65 specific activities were significantly less, however, in the particulate material than in the water. This difference indicates that equilibrium of Zn between particulate material and water had not been reached after 9 months. Three months later (December 1969) 65Zn specific activities were determined again for particulate material and total dissolved Zn. The mean specific activity of 65Zn in the particulate samples showed a small but significant increase, but it was still less than in the water. Concentration factors in the particulate matter were 980 for 65Zn and 1400 for total Zn. Samples of benthic algae taken in March 1970 had a mean specific activity of 65Zn similar to the mean 65Zn specific activity of water samples taken 3 months earlier.

scholarly journals Assessment of Levels of Natural Radioactivity in Sand Samples Collected from Ekalakala in Machakos County, Kenya

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Lucia Nyiva Munyao ◽  
Daniel Kipngetich Ketui ◽  
Calford Otieno ◽  
Margaret Wairimu Chege
Keyword(s):  
Dose Rate ◽  
Specific Activity ◽  
Mean Value ◽  
Average Dose ◽  
Radiation Dose Rate ◽  
World Average ◽  
The World ◽  
The Mean ◽  
Specific Activities ◽  
Significant Health

Construction sand is naturally polluted with radionuclides of terrestrial origin. In this study, specific activities of 238U, 232Th, and 40K in 30 sand samples collected along the Ekalakala River, Machakos County, Kenya, were measured using a high-purity germanium γ-ray spectrometer. The specific activities ranged between 9.7 Bqkg−1 and 24.0 Bqkg−1, 11.5 Bqkg−1 and 26.2 Bqkg−1, and 820 Bqkg−1 and 1850 Bqkg−1 for 238U, 232Th, and 40K, respectively. While the mean specific activities for 238U and 232Th were less than half of the world average values of 33 Bqkg−1 and 45 Bqkg−1, respectively, the average specific activity of 40K was significant since it was three times the global mean value of 420 Bqkg−1. A calculated absorbed radiation dose rate for the sand varied between 46.8 nGyh−1 and 94.2 nGyh−1 with a mean of 68.5 ± 13.3 nGyh−1. This is not significantly different from the world average dose rate of 60 nGyh−1 for geological samples. The AEDR and Hex had maximum values of 0.29 mSvy−1 and 0.52, respectively, both within the recommended limits of radiation exposure for members of the general public. Based on these results, the sand from Ekalakala River does not pose significant health implication to the sand harvesters as well as the inhabitants of the houses constructed using this sand.

scholarly journals The exploration of Thermococcus barophilus lipidome reveals the widest variety of phosphoglycolipids in Thermococcales.

2021 ◽  
Author(s):  
Maxime Tourte ◽  
Sarah Coffinet ◽  
Lars Wormer ◽  
Julius Sebastian Lipp ◽  
Kai-Uwe Hinrichs ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Lipid Extraction ◽  
General Nature ◽  
Head Group ◽  
Polar Head Group ◽  
Polar Head ◽  
Archaeal Lipids ◽  
Group Compositions ◽  
First Time ◽  
Derivatives Of

One of the most distinctive characteristics of Archaea is their unique lipids. While the general nature of archaeal lipids has been linked to their tolerance to extreme conditions, little is known about the diversity of lipidic structures Archaea are able to synthesize, which hinders the elucidation of the physicochemical properties of their cell membrane. In an effort to widen the known lipid repertoire of the piezophilic and hyperthermophilic model archaeon Thermococcus barophilus, we comprehensively characterized its intact polar lipid (IPL), core lipid (CL), and polar head group compositions using a combination of cutting-edge liquid chromatography and mass spectrometric ionization systems. We tentatively identified 82 different IPLs based on five distinct CLs and 10 polar head group derivatives of phosphatidylhexoses, including compounds reported here for the first time, e.g., di-N-acetylhexosamine phosphatidylhexose-bearing lipids. Despite having extended the knowledge on the lipidome, our results also indicate that the majority of T. barophilus lipids remain inaccessible to current analytical procedures and that improvements in lipid extraction and analysis are still required. This expanded yet incomplete lipidome nonetheless opens new avenues for understanding the physiology, physicochemical properties, and organization of the membrane in this archaeon as well as other Archaea.

Temperature-induced alterations in phospholipids of Fusarium oxysporum f. sp. lycopersici

1976 ◽  
Vol 22 (4) ◽  
pp. 557-562 ◽  
Author(s):  
Leslie R. Barran ◽  
Richard W. Miller ◽  
Ian de la Roche
Keyword(s):  
Fusarium Oxysporum ◽  
Growth Temperature ◽  
Group Composition ◽  
Head Group ◽  
Polar Head Group ◽  
Membrane Phospholipids ◽  
Polar Head ◽  
Degree Of Unsaturation ◽  
Total Membrane

Ten phospholipids were identified in hyphal membrane preparations of Fusarium oxysporum f. sp. lycopersici when the cells were grown to the late log phase at 15, 25, and 37 °C, respectively. The major phospholipids present were phosphatidylcholine (PC) and phosphatidylethanolamine (PE), which together made up about 70% of the total membrane phospholipids. The degree of unsaturation in the acyl group of the phospholipids was inversely related to growth temperature. The polar head group composition was also affected by growth temperature. Cells grown at 15 and 25 °C contained the same relative proportions of PC and PE, but when the growth temperature was raised to 37 °C, the ratio of PC to PE was doubled. A methylating system capable of converting PE to PC was demonstrated in vitro.

scholarly journals Profile of Phosphatidylserine Modifications under Nitroxidative Stress Conditions Using a Liquid Chromatography-Mass Spectrometry Based Approach

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 107 ◽  
Author(s):  
Bruna Neves ◽  
Pedro Domingues ◽  
Maria Oliveira ◽  
Maria Domingues ◽  
Tânia Melo
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Acyl Chain ◽  
Fatty Acyl ◽  
Head Group ◽  
Fatty Acyl Chain ◽  
Polar Head Group ◽  
Derivatives Of

Nitrated lipids have been detected in vitro and in vivo, usually associated with a protective effect. While nitrated fatty acids have been widely studied, few studies reported the nitration and nitroxidation of the phospholipid classes phosphatidylcholine, and phosphatidylethanolamine. However, no information regarding nitrated and nitroxidized phosphatidylserine can be found in the literature. This work aims to identify and characterize the nitrated and nitroxidized derivatives of 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphoserine (POPS), obtained after incubation with nitronium tetrafluoroborate, by liquid chromatography (LC) coupled to mass spectrometry (MS) and tandem MS (MS/MS). Several nitrated and nitroxidized products were identified, namely, nitro, nitroso, nitronitroso, and dinitro derivatives, as well as some nitroxidized species such as nitrosohydroxy, nitrohydroxy, and nitrohydroperoxy. The fragmentation pathways identified were structure-dependent and included the loss of HNO and HNO2 for nitroso and nitro derivatives, respectively. Combined losses of PS polar head group plus HNO or HNO2 and carboxylate anions of modified fatty acyl chain were also observed. The nitrated POPS also showed antiradical potential, demonstrated by the ability to scavenge the ABTS●+ and DPPH● radicals. Overall, this in vitro model of nitration based on LC-MS/MS provided additional insights into the nitrated and nitroxidized derivatives of PS and their fragmentation fingerprinting. This information is a valuable tool for targeted analysis of these modified PS in complex biological samples, to further explore the new clues on the antioxidant potential of nitrated POPS.

Influence of temperature and growth phase on desaturase activity of the mesophilic yeast Candida lipolytica

1983 ◽  
Vol 61 (4) ◽  
pp. 171-177 ◽  
Author(s):  
G. Ferrante ◽  
Y. Ohno ◽  
M. Kates
Keyword(s):  
Desaturase Activity ◽  
Specific Activity ◽  
Aeration Rate ◽  
C Cells ◽  
Candida Lipolytica ◽  
Influence Of Temperature ◽  
Degree Of Unsaturation ◽  
Microsomal Membranes ◽  
Specific Activities ◽  
Temperature And Growth

Microsomal membranes prepared from Candida lipolytica cells grown at 10 °C had a higher lipid content and degree of unsaturation than membranes prepared from cells grown at 25 °C. The specific activities of stearoyl-CoA (18:0-CoA), oleoyl-CoA (18:1-CoA), and dioleoyl phosphatidylcholine (18:1-PC) desaturases in microsomes of cells grown at either 25 or 10 °C showed maximum values near midlog phase, coinciding with the respective maximum absolute content of linoleic (18:2) in the microsomal preparations. The 18:1-CoA desaturase activity in 10 °C cells was nearly double that in 25 °C cells, while the 18:0-CoA and 18:1-PC desaturases had considerably lower activities in 10 °C cells. An increase in aeration rate (shaking speed, 70 to 130 rpm) resulted in increased proportions of 18:2 (32 to 47%, respectively) in microsomes of cells grown at 25 °C and in increased 18:1-CoA desaturase specific activity (83 to 140 pmol∙min−1∙mg−1); however, no significant changes occurred in 18∙0-CoA or 18:1-PC desaturase activities.

An International Collaborative Study to Investigate Standardisation of Hirudin Potency

1993 ◽  
Vol 69 (05) ◽  
pp. 430-435 ◽  
Author(s):  
Colin Longstaff ◽  
Man-Yu Wong ◽  
Patrick J Gaffney
Keyword(s):  
Specific Activity ◽  
Collaborative Study ◽  
Residual Activity ◽  
Quality Standard ◽  
Upper Limit ◽  
Assay Procedure ◽  
Specific Activities ◽  
International Collaborative ◽  
Range Of Values ◽  
International Collaborative Study

SummaryAn international collaborative study has been carried out to investigate the reproducibility of hirudin assays in 13 laboratories using four recombinant hirudins and one natural, sulphated product. A simple assay procedure was proposed involving the titration of α-thrombin with inhibitor and measurement of residual activity using a chromogenic substrate. A standard α-thrombin preparation was supplied to ensure that this reagent was of uniform quality throughout the study. The method appeared to present no difficulties and laboratories reported similar potencies for the 5 hirudin samples, in line with expected values. This gave 200–222 Thrombin Inhibitory Units/ampoule (TIU/ampoule) of lyophilised hirudin, with geometric coefficient of variation (gcv) values ranging from 10.15–15.97%. This corresponds to specific activities of approximately 14,300–15,900 TIU/mg protein. This is close to the upper limit of previously reported values of specific activity. We conclude that the precision of this determination compared with the wider range of values in the literature (8,000–16,000 thrombin inhibitory units [TIU]/mg) results from the use of good quality standard α-thrombin by all laboratories. This study has important implications for hirudin standardisation.

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