Relationship of Oxygen to the Activity of GR-S Reclaiming Agents

1955 ◽  
Vol 28 (1) ◽  
pp. 308-321
Author(s):  
R. B. Bennett ◽  
G. E. P. Smith
Keyword(s):  
Molecular Weight ◽  
Oxygen Content ◽  
Low Molecular Weight ◽  
Constant Amount ◽  
Experimental Conditions ◽  
Physical Conditions ◽  
Subsequent Exposure ◽  
Relationship Of

Abstract 1. An alkylphenol sulfide reclaiming agent was found to have little activity in the absence of oxygen ; conversely oxygen produced little activity without the reclaiming agent. Together, the oxygen and reclaiming agent showed exceptional activity in attacking a sulfur-cured GR-S gum vulcanizate to produce soluble, low molecular-weight fragments under relatively mild experimental conditions. 2. The solubilizing effects of oxygen with reclaiming oils and the alkylphenol sulfide reclaiming agent were produced without significant increase of the amount of combined oxygen in the acetone or chloroform insoluble portions of the vulcanizate. Large increases of oxygen content were produced quickly by subsequent exposure of the treated and extracted samples to an atmosphere of oxygen. 3. No significant quantity of combined sulfur was removed under experimental conditions involving an excess of liquid reclaiming oils and agents. However, a significant, constant amount of sulfur was removed under conditions in which only small amounts of the reclaiming oils and agents were carried on the surface of the ground vulcanizates. This loss of sulfur was independent of both oxygen and of reclaiming aid and appeared to depend solely on the type of stock and on the physical conditions employed.

scholarly journals Galloylglucoses of low molecular weight as mordant in electron microscopy. I. Procedure, and evidence for mordanting effect.

1976 ◽  
Vol 70 (3) ◽  
pp. 608-621 ◽  
Author(s):  
N Simionescu ◽  
M Simionescu
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Tannic Acid ◽  
Sodium Borohydride ◽  
Low Molecular Weight ◽  
High Contrast ◽  
Experimental Conditions ◽  
Complex Effect ◽  
Tissue Contrast ◽  
Tissue Specimens

Gallotannin, consisting mainly of low molecular weight esters such as penta- and hexagalloylglucoses (commercially available as tannic acid produced from Turkish nutgall), can be used for increasing and diversifying tissue contrast in electron microscopy. When applied on tissue specimens previously fixed by conventional methods (aldehydes and OsO4), the low molecular weight galloylglucoses (LMGG) penetrate satisfactorily the cells and induce general high contrast with fine delineation of extra- and intracellular structures, especially membranes. In some features, additional details of their intimate configuration are revealed. Various experimental conditions tested indicate that the LMGG display a complex effect on fixed tissues: they act primarily as a mordant between osmium-treated structures and lead, and concomitantly stabilize some tissue components against extraction incurred during dehydration and subsequent processing. Experiments with aldehyde blocking reagents (sodium borohydride and glycine) suggested that the LMGG mordanting effect is not dependent on residual aldehydes groups in tissues.

Design of Low Molecular Weight Hematoregulatory Agents from the Structure−Activity Relationship of a Dimeric Pentapeptide

1997 ◽  
Vol 40 (18) ◽  
pp. 2876-2882 ◽  
Author(s):  
Alan S. Cuthbertson ◽  
Mette Husbyn ◽  
May Engebretsen ◽  
Michael Hartmann ◽  
Meinolf Lange ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Low Molecular Weight ◽  
Structure Activity ◽  
Relationship Of

Characterization of Low Molecular Weight Hydrocarbons in Jingbian Gas Field and its Application to Gas Sources Identification

2011 ◽  
Vol 29 (6) ◽  
pp. 777-795 ◽  
Author(s):  
Guoyi Hu ◽  
Shuichang Zhang
Keyword(s):  
Molecular Weight ◽  
Stable Carbon Isotopes ◽  
Ordos Basin ◽  
Low Molecular Weight ◽  
Gas Field ◽  
Average Value ◽  
Weathered Crust ◽  
Relationship Of ◽  
Compound Specific Carbon Isotope ◽  
Coal Measures

Chemical and isotopic compositions of C6-C7 low molecular weight hydrocarbons (LMWHs) were used to determine the origin of gas in the Ordovician weathered crust (O1m5) reservoir of Jingbian gas field in Ordos Basin, China. GC quantification of LMWHs for 55 gas samples [20 of them from the Xiashihezi Formation (P1x) and Shanxi Formation (P1s) reservoirs, and the rest from the O1m5 reservoir] were conducted. The compound specific stable carbon isotopes of LMWHs for 24 gas samples (five gas samples from the P1s reservoir) were analyzed with GC-C-IRMS. The results show that cycloalkanes are abundant components and their concentrations range from 23.8–52.5% with an average of 41.1% among LMWHs. Methylcyclohexane (MCH) is the most abundant one among normal heptane ( n-C7), MCH and dimethylcyclopentane (DMCP), ranging from 50.1–81.4% with an average value of 71.6%. A13C enrichment for nine compounds of C6-C7 fraction was observed, and the δ13C values range from −25.4–16.3%. Based on the correlation of the Mango parameters (K1 and K2), the relationship of n-C7, MCH and DMCP and compound specific carbon isotope of C6-C7 compounds, the gas in the O1m5 reservoir shares the same origin with that in the P1x, P1s reservoirs, the natural gas in Ordovician weathered crust reservoir and Permian sandstone reservoir sourced from coal measures in Carboniferous and Permian.

Dermatan Sulfate Is a More Potent Inhibitor of Clot-bound Thrombin than Unfractionated and Low Molecular Weight Heparins

1994 ◽  
Vol 71 (05) ◽  
pp. 576-580 ◽  
Author(s):  
P Bendayan ◽  
H Boccalon ◽  
D Dupouy ◽  
B Boneu
Keyword(s):  
Molecular Weight ◽  
Dermatan Sulfate ◽  
Potent Inhibitor ◽  
Final Concentration ◽  
Coagulation Cascade ◽  
Low Molecular Weight ◽  
Dependent Manner ◽  
Low Molecular Weight Heparins ◽  
Experimental Conditions

SummaryClot-bound thrombin proteolyses fibrinogen and amplifies the coagulation cascade at its close vicinity, thereby ensuring the growth of fibrin-rich thrombus. The present study compares the ability of various glycosaminoglycans (GAGs) to inhibit these 2 properties. Unfractionated heparin (UH), 3 low molecular weight heparins (LMWHs) with increasing antifactor Xa/antifactor Ha ratio, the synthetic pentasaccharide (PS), devoid of antifactor Ha activity, and dermatan sulfate (DS), a catalyst of thrombin inhibition by heparin cofactor II, were selected on the basis of their different properties. Proteolysis of fibrinogen by clot-bound thrombin was evaluated by measuring fibrinopeptide A (FPA) generation after an incubation of standardized washed clots in plasma for 120 min in absence or in presence of increasing concentrations of heparins or of DS. The results were compared to those obtained when free a-thrombin (0.4 nM) was added to plasma in the same experimental conditions. On the basis of equivalent antithrombin units, UH and LMWHs gave identical results. To inhibit by 70% fibrinogen proteolysis induced by clot-bound thrombin (IC 70), 5- to 9-fold higher concentrations of UH or of LMWHs were required in comparison with those required to inhibit free thrombin. For DS, only a 1.3 times higher concentration was required. PS (final concentration 1 anti Xa U • ml-1) was devoid of any inhibitory effect. The amplification of the coagulation cascade induced by dot-bound thrombin was evaluated by measuring the shortening of whole blood clotting time (WBCT) resulting from the incubation of washed clots in native blood. In absence of GAG, clot-bound thrombin reduced WBCT from 18 ± 2 min to 9 ± 1 min. Each GAG prolonged WBCT in a dose-dependent manner but these prolongations were smaller in presence of washed clots. The most potent agent to suppress the shortening of WBCT was DS. LMWH and UH were less effective and PS (final concentration 1 anti Xa U/ml) was almost ineffective. Therefore, in these in vitro experiments, DS is a more potent inhibitor of clot-bound thrombin than heparin. Whether or not these observations are relevant for the treatment of established deep-vein thrombosis requires comparative clinical studies.

Catabolism of Fibrinogen and its Derivatives

1977 ◽  
Vol 38 (04) ◽  
pp. 0809-0822 ◽  
Author(s):  
Laurence A. Sherman
Keyword(s):  
Experimental Data ◽  
Molecular Weight ◽  
Degradation Products ◽  
Reticuloendothelial System ◽  
Hepatic Uptake ◽  
Low Molecular Weight ◽  
Cell Membrane Binding ◽  
Relationship Of ◽  
The Relationship

SummaryAlthough the site and manner of normal catabolism of most of the fibrinogen pool is uncertain, certain pathways have been defined for various fibrinogen derivatives. Several organs, including the kidneys and reticuloendothelial system (RES) have been directly implicated as catabolic sites for various fibrinogen derivatives. The catabolic sites are not the same for different derivatives. These differences in catabolism are probably in part related to biochemical differences between fibrinogen and its various derivatives. Fibrinogen itself may be catabolized in endothelial cells, although little experimental data is available. RES uptake of intact fibrinogen does not occur, and removal of sialic acid does not result in the rapid hepatic uptake seen with other desialop rote ins. In contrast, a variety of studies have shown that fibrin is taken up by the RES by at least 2 mechanisms. The first is phagocytosis of microparticulate fibrin. The second involves a RES cell membrane binding of soluble fibrin which remains soluble in the blood, when complexed to fibrinogen or degradation products. Fibrinogen degradation products alone may in part also be cleared in the RES. Fragments D and E appear to be catabolized in the kidney, although both the intrarenal site of catabolism and the means of cellular uptake is unknown. It is clear that normally there is no urinary excretion of D and E. Another fibrinogen derivative, low molecular weight clottable fraction 1–8, is derived in vivo from intact fibrinogen. 1–8 is found normally in the blood and has a shorter t ½ than fibrinogen although much longer than D and E. While originally thought to be the result of limited plasmin degradation, 1–8 may be the result of another type of proteolysis. The sites of both 1–8 formation and degradation are unknown. Catabolism via fibrin, 1–8, or D and E appears to be only a small percent of normal turnover, albeit of much greater significance in disease. The relationship of these pathways to the as yet unknown catabolic site for the bulk of normal fibrinogen remains to be determined.

Effect Of Some Experimental Conditions On The Activity Of A Low Molecular Weight (LMW) Heparin Fraction Compared To A Hight Molecular Weight (HMW) Fraction

1981 ◽  
Author(s):  
M Aiach ◽  
C Nussas ◽  
J Mardiguian
Keyword(s):  
Molecular Weight ◽  
Incubation Time ◽  
Factor Xa ◽  
Low Molecular Weight ◽  
Experimental Conditions ◽  
Assay Procedure ◽  
At Iii ◽  
Parabolic Function ◽  
Heparin Activity ◽  
Antiprotease Activity

In this work, we aimed to demonstrate that different methods can give different results when the same pair of heparin samples are compared, even when specific antiprotease assays are performed. For this purpose, the effect of heparin on factor Xa (Xa) or thrombin (IIa) inhibition by antithrombin III (AT III) was examined in the presence of varying amounts of AT III, during different incubation times.The molecular weight of the two heparins were 5,200 (LMW) and 42,000 (HMW). Solutions containing 2 y.g per ml of heparin and a 1.4 to 15 μM freshly purified human AT III were incubated with either bovine Xa or human Ila. After a 20, 30, 60 or 90 secondes incubation at 30° C, the remaining protease activity was measured by the initial velocity of a chromogenic substrate. The method was entirely automated using a reaction rate analyser and an adapted program.The antiprotease activity of the LMW heparin (related to the HMW heparin activity) varied from 0.23 to 0.89 in the anti Xa system, from 0.30 to 0.77 in the anti Ila system. The ratio of LMW to HMW activity was a parabolic function of either AT III concentration or incubation time. No meaning differences were observed between anti Xa and anti Ila activity when the inhibiting capacity was assayed in the same experimental conditions. These results suggest that the relative activities of HMW and LMW fractions depend upon the assay procedure. AT III concentration as well as incubation time are of particular importance.

scholarly journals Control of the fructose 6-phosphate/fructose 1,6-bisphosphate cycle in isolated hepatocytes by glucose and glucagon. Role of a low-molecular-weight stimulator of phosphofructokinase

1980 ◽  
Vol 192 (3) ◽  
pp. 887-895 ◽  
Author(s):  
Emile Van Schaftingen ◽  
Louis Hue ◽  
Henri-Géry Hers
Keyword(s):  
Molecular Weight ◽  
Incubation Medium ◽  
Liver Extract ◽  
Gel Filtration ◽  
Isolated Hepatocytes ◽  
Low Molecular Weight ◽  
Experimental Conditions ◽  
Fructose 1,6 Bisphosphate ◽  
Acid Labile

1. Recycling of metabolites between fructose 6-phosphate and triose phosphates has been investigated in isolated hepatocytes by the randomization of carbon between C(1) and C(6) of glucose formed from [1-14C]galactose. 2. Randomization of carbon atoms was regularly observed with hepatocytes isolated from fed rats and was then little influenced by the concentration of glucose in the incubation medium. It was decreased by about 50% in the presence of glucagon. 3. Randomization of carbon atoms by hepatocytes isolated from starved rats was barely detectable at physiological concentrations of glucose in the incubation medium, but was greatly increased with increasing glucose concentrations. It was nearly completely suppressed by glucagon. These large changes can be attributed to parallel variations in the activity of phosphofructokinase. 4. The main factors that appear to control the activity of phosphofructokinase under these experimental conditions are the concentration of fructose 6-phosphate, the concentration of fructose 1,6-bisphosphate and also the affinity of the enzyme for fructose 6-phosphate. 5. The affinity of phosphofructokinase for fructose 6-phosphate was diminished by incubation of the cells in the presence of glucagon and also by filtration of an extract of hepatocytes through Sephadex G-25 and by purification of the enzyme. When assayed at 0.25 or 0.5mm-fructose 6-phosphate, the activity of phosphofructokinase present in a liver Sephadex filtrate was increased by a low-molecular-weight effector, which could be isolated from a liver extract by ultrafiltration, gel filtration or heat treatment, but was rapidly destroyed in trichloroacetic acid, even in the cold. This effector appears to be a highly acid-labile phosphoric ester. Its concentration was greatly increased in hepatocytes incubated in the presence of glucose and was decreased in the presence of glucagon.

Assessment of venous thromboembolism treatment in patients with cancer on low molecular weight heparin, warfarin, and the direct oral anticoagulants

2017 ◽  
Vol 25 (2) ◽  
pp. 261-268 ◽  
Author(s):  
Ellen M Uppuluri ◽  
Kelly R Burke ◽  
Christina Mactal Haaf ◽  
Nancy L Shapiro
Keyword(s):  
Molecular Weight ◽  
Venous Thromboembolism ◽  
Low Molecular Weight Heparin ◽  
Oral Anticoagulants ◽  
Direct Oral Anticoagulants ◽  
Low Molecular Weight ◽  
Bleeding Events ◽  
Safety And Efficacy ◽  
Patients With Cancer ◽  
Relationship Of

Background Direct oral anticoagulants (DOACs) are not recommended for venous thromboembolism (VTE) treatment in patients with cancer because their safety and efficacy have not been compared to low molecular weight heparin (LMWH) in large trials. Routine anti-Xa monitoring in cancer patients on LMWH is also not recommended due to limited data correlating anti-Xa levels and outcomes. Objective Compare the safety and efficacy of DOACs to LMWH and warfarin and assess the relationship of anti-Xa monitoring and outcomes in patients with cancer taking LMWH in an urban university setting. Methods This retrospective, cohort study analyzed the recurrence of VTE and number of bleeding events in patients with cancer. Results There were 131 patients included in the analysis. There was no difference seen in the rate of recurrent VTEs between the LMWH, warfarin and DOAC groups (9.3%, 5.9%, 9.1%, p = 0.89). There was also no difference in the rate of bleeding between groups (10.5%, 14.7%, 9.1%, p = 0.576). There was an increased rate of mortality seen in the LMWH group (26.7% vs. 2.9% vs. 18.2%, p = 0.006). There was no difference seen in recurrent VTE (10.3% vs. 8.5%, p = 0.53) or bleeding (10.3% vs. 10.7%, p = 0.661) between the monitored and unmonitored LMWH patients. Conclusion Results of this analysis suggest DOACs may be as safe and effective as LMWH and warfarin for the treatment of VTE in patients with cancer, and there may be no clinical benefit to routine anti-Xa monitoring in patients on LMWH treatment. However, larger studies are needed to confirm these observations.

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