scholarly journals Structural investigations on the lignin–carbohydrate complexes of Lolium perenne

1974 ◽  
Vol 139 (1) ◽  
pp. 197-204 ◽  
Author(s):  
Ian M. Morrison
Keyword(s):  
Molecular Weight ◽  
Leaf Blade ◽  
Alkaline Treatment ◽  
Leaf Sheath ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Coumaric Acid ◽  
Borohydride Reduction ◽  
Structural Investigations ◽  
The Individual

1. Lignin–carbohydrate complexes isolated from leaf blade, leaf sheath and stem tissue of ryegrass by extraction with dimethyl sulphoxide were examined by fractionation procedures. Although the complexes are heterogeneous, heterogeneity is shown only in the ratio of the individual monosaccharide residues and not in the ratio of lignin to carbohydrate. 2. The molecular weight of the complexes is high (≥150000), but chemical modification by alkaline hydrolysis, borohydride reduction or lead tetra-acetate oxidation does not drastically decrease it. Low-molecular-weight fragments released by alkaline treatment were shown to contain acetic acid, ferulic acid and p-coumaric acid. 3. On the basis of the chemical stability of the complexes, it is postulated that at least three types of bonding may be present between lignin and carbohydrate, namely one cleaved on borohydride reduction, another cleaved by alkali and a linkage resistant to alkali. 4. The carbohydrate portion of the complexes is composed of β-(1→4)-linked d-glucose residues (cellulose) and β-(1→4)-linked chains of xylose residues. Side chains involving arabinose and galactose residues are linked to C-3 of some of the xylose residues. 5. How the components of the complexes are held together is not certain, but it is suggested that the phenolic acids may act as cross-linking agents.

Molecular weight determines the frequency of delayed type hypersensitivity reactions to heparin and synthetic oligosaccharides

2005 ◽  
Vol 94 (12) ◽  
pp. 1265-1269 ◽  
Author(s):  
Susanne Alban ◽  
Roland Kaufmann ◽  
Edelgard Lindhoff-Last ◽  
Wolf-Henning Boehncke ◽  
Ralf J. Ludwig ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Heparin Therapy ◽  
Delayed Type Hypersensitivity ◽  
Published Data ◽  
Low Molecular Weight ◽  
Hypersensitivity Reactions ◽  
Type Iv ◽  
Total Data ◽  
The Individual

SummaryEczematous lesions, resulting from type IV sensitizations are well-known and relatively frequent cutaneous adverse effects of s.c. heparin therapy. If anticoagulation is further required intravenous heparin, heparinoids or lepirudin may be used as a substitute. However, these alternatives are not optimal in terms of practicability and/or safety-profiles. As molecular weight of different heparin preparations has repetitively been implied to determine the frequency of sensitization, we hypothesized, that due to its low molecular weight the pentasaccharide fondaparinux may provide a practicable and safe anticoagulant therapy in patients with delayed type hypersensitivity reactions (DTH) to heparin and other oligosaccharides. To test this concept, patients referred for diagnosis of cutaneous reactions after s.c. anticoagulant treatment underwent a series of in vivo skin allergyand challenge-tests with unfractionated heparin, a series of low molecular weight heparins (nadroparin, dalteparin, tinzaparin, enoxaparin and certoparin), the heparinoid danaparoid and the synthetic pentasaccharide fondaparinux. In total, data from twelve patients was evaluated. In accordance with previously published data, we report a high crossreactivity among heparins and heparinoids. In contrast – and in support of our initial hypothesis – sensitization towards the synthetic pentasaccharide fondaparinux was rarely observed. Plotting the cumulative incidence against the determined molecular weight of the individual anticoagulant preparations, shows that molecular weight generally is a key determinant of sensitization towards heparins and other oligosaccharides (r2=0.842, p=0.009). Hence, fondaparinux may be used as a therapeutic alternative in patients with cutaneous DTH relations towards heparin and other polysaccharides.

Calcium-Dependent Cross-Linking Processes in Platelets

1979 ◽  
Author(s):  
I. Cohen ◽  
T. Glaser
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Tracer Concentration ◽  
Calcium Dependent ◽  
A 23187 ◽  
Polymer Formation ◽  
Total Disappearance ◽  
Low Molecular Weight Proteins

When platelet cytoplasmic Ca2+ is increased by the ionophore A 23187, there is the coincident appearance of a cross-linked polymer and the partial disappearance of five high molecular weight polypeptide bands (> 145,000). The glycoproteins show a partial disappearance of bands lb, IIb and IV and the total disappearance of hands la and Ilia. The disappearance of the protein bands, possibly contributing to the polymer formation, is prevented by histamine, aminoacetonltrile and cystamlne, which, as pseudodonor amines are known Inhibitors of factor XHIa-catalyzed cross-linking. 14C-histamine, at a tracer concentration, was incorporated into the polymer as well as into myosin, glycoproteins IIb and IIIa (α-actinln), actin and two unidentified low-molecular weight proteins. The polymer formed is also apparent in isolated membranes following the iono-phore-stimulated increase in intracellular Ca2+. These findings are unrelated to a proteolytic activity since the platelet Ca2+-dependent proteases are inhibited by leupep-tin. Ca2+-activation of a platelet cytosol transamidase would explain the data obtained. This platelet transamidase(s) may couple membrane proteins to cytoplasmic contra-tlle proteins. Thus, a new concept is proposed for the stabilization of platelet membranes and platelets as they form the hemostatic plug.

scholarly journals Low molecular weight ε-caprolactone-p-coumaric acid copolymers as potential biomaterials for skin regeneration applications

PLoS ONE ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. e0214956 ◽  
Author(s):  
Marco Contardi ◽  
Alejandro Alfaro-Pulido ◽  
Pasquale Picone ◽  
Susana Guzman-Puyol ◽  
Luca Goldoni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Skin Regeneration ◽  
Low Molecular Weight ◽  
Coumaric Acid

scholarly journals Binding Affinity, Cellular Uptake, and Subsequent Intracellular Trafficking of the Nano-Gene Vector P123-PEI-R13

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Yaguang Zhang ◽  
Hongmei Shu ◽  
Jing Hu ◽  
Min Zhang ◽  
Junweng Wu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Cellular Uptake ◽  
Intracellular Trafficking ◽  
Transfection Efficiency ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Gene Vector ◽  
Dna Complexes ◽  
Dynamic Source

A nano-gene vector PEI-P123-R13 was synthesized by cross-linking low molecular weight PEI with P123 and further coupling bifunctional peptide R13 to the polymer for targeting tumor and increasing cellular uptake. The binding assessment of R13 toαvβ3 positive cells was performed by HRP labeling. The internalization pathways of P123-PEI-R13/DNA complexes were investigated based on the effect of specific endocytic inhibitors on transfection efficiency. The mechanism of intracellular trafficking was investigated based on the effect of endosome-lysosome acidification inhibitors, cytoskeleton, and dynein inhibitors on transfection efficiency. The results indicated that the bifunctional peptide R13 had the ability of binding toαvβ3 positive cellsin vitro. The modification of P123-PEI-R13 with R13 made it display new property of internalization. P123-PEI-R13/DNA complexes were conducted simultaneously via clathrin-mediated endocytosis, caveolin-mediated endocytosis, macropinocytosis, and possible energy-independent route. After internalization, P123-PEI-R13/DNA complexes could escape from the endosome-lysosome system because of its acidification and further took microtubule as the track and dynein as the dynamic source to be transported toward the microtubule (+) end, to wit nucleus, under the action of microfilament, and with the aid of intermediate filament.

Mechanically robust, readily repairable polymers via tailored noncovalent cross-linking

Science ◽  
2017 ◽  
Vol 359 (6371) ◽  
pp. 72-76 ◽  
Author(s):  
Yu Yanagisawa ◽  
Yiling Nan ◽  
Kou Okuro ◽  
Takuzo Aida
Keyword(s):  
Molecular Weight ◽  
Polymer Chains ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Structural Element ◽  
Reasonable Time ◽  
Diffusion Dynamics ◽  
Important Challenge ◽  
Sustainable Societies ◽  
Hydrogen Bonded

Expanding the range of healable materials is an important challenge for sustainable societies. Noncrystalline, high-molecular-weight polymers generally form mechanically robust materials, which, however, are difficult to repair once they are fractured. This is because their polymer chains are heavily entangled and diffuse too sluggishly to unite fractured surfaces within reasonable time scales. Here we report that low-molecular-weight polymers, when cross-linked by dense hydrogen bonds, yield mechanically robust yet readily repairable materials, despite their extremely slow diffusion dynamics. A key was to use thiourea, which anomalously forms a zigzag hydrogen-bonded array that does not induce unfavorable crystallization. Another key was to incorporate a structural element for activating the exchange of hydrogen-bonded pairs, which enables the fractured portions to rejoin readily upon compression.

THE ANIONIC POLYMERIZATION OF ALLYL ACRYLATE AND OF ALLYL METHACRYLATE

1966 ◽  
Vol 44 (6) ◽  
pp. 695-702 ◽  
Author(s):  
S. Bywater ◽  
P. E. Black ◽  
D. AM. Wiles
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
Allyl Alcohol ◽  
Polymer Chains ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Carbonyl Groups ◽  
Double Bonds ◽  
Soluble Product ◽  
Allyl Methacrylate

The low temperature polymerization of allyl acrylate in toluene solution has been investigated with n-butyllithium and 1,1-diphenyl-n-hexyllithium initiators. The latter was also used in a study of the polymerization of allyl methacrylate under the same conditions. The reactions between initiator and monomer were rapid in all cases. More than half of the initiator molecules reacted with monomer acrylic double bonds to start polymer chains, only a few of which grew to a high molecular weight, highly isotactic product. Most of the chains remained as a low molecular weight, precipitant-soluble product. The remaining initiator molecules reacted with the carbonyl groups of the monomers to produce species which could be detected as allyl alcohol, after termination of the reaction with acetic acid. The allyl double bonds were not involved in reactions during polymerization but were presumably responsible for the cross-linking which occurred when the polymers were exposed to air.

Clinical and Laboratory Validation of the 2nd International Standard of Low Molecular Weight Heparin (IS 2003-01/608) in the Anti-Xa, Anti-LIA Heptest and Prothrombinase Induced Clotting (PiCT) Tests.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4147-4147
Author(s):  
D. Hoppensteadt ◽  
W. Jeske ◽  
D. Fareed ◽  
F. Baltasar ◽  
J. M. Walenga ◽  
...  
Keyword(s):  
Molecular Weight ◽  
International Standards ◽  
Clinical Monitoring ◽  
Low Molecular Weight ◽  
Therapeutic Trial ◽  
Global Test ◽  
International Standard ◽  
Assay Methods ◽  
The Individual ◽  
Concentration Curves

Abstract Background: Because of the relative insensitivity of the global clot based assays such as the activated partial thromboplastin time (APTT), the low molecular weight heparins (LMWHs) are potency evaluated/optimized in the anti-Xa (AXa) and heptest. A new clot based assay namely, prothrombin induced clotting time (PiCT) is sensitive to the anticoagulant effects of LMWHs and related drugs. As the LMWHs are standardized using the anti-Xa methods, using the International Standards, this study was designed to cross validate the 2nd International Standard for LMWHs(NIBSC 01/608) in various assay methods. Methods: Commercially available LMWHs, Dalteparin (D), Enoxaparin (E), Tinzaparin (T) and the 1st International Standard (85/600) were crossed referenced against the 2nd International Standard (NIBSC 01/608) using an amidolytic AXa method. Each of these LMWHs were compared in the AXa, adjusted concentration range of 0–1.0 U/ml using the Heptest, AXa, AIIa and PiCT. In addition plasma samples from patients receiving a LMWH, E for therapeutic and interventional purposes were measured using various tests. Results: The AXa potency adjusted LMWHs (D, E, and T) and 1st International Standard provided superimposable concentration curves in the amidolytic AXa assays. However marked differences in the heptest and PiCT were noted. Major differences were noted in the AIIA levels, even between the two International standards. When patients samples (n=75) from a therapeutic trial (1.0 mg/kg BID/SC) were evaluated, assay based differences were further amplified. The amidolytic AXa assay consistently measured higher AXa levels. When the two standards were cross-referenced with one another in different assays, major differences were noted in the clot-based assays. Even in the AXa assay at equivalent AXa levels, differences were obvious. Conclusions: These results suggest that both of the International Standards of LMWH are valid for only the cross standardization of the AXa activities of LMWHs. If any of the other methods were used, significantly different results were obtained with each of the individual LMWHs. Thus, the 2nd International Standard should only be used for amidolytic AXa assay for potency referencing purposes. Moreover, the stated potency of the 2nd Internation Standard may need to be readjusted against the 1st Standard to obtain valid results. These standards are of limited value in the clinical monitoring of LMWHs. It is therefore proposed that each of the LMWHs should be cross referenced by its own standard and the clinical monitoring of these drugs should only be carried out utilizing the specific drug used in a given patient. The PiCT test offers a global test which is capable of monitoring the effects of all components of heparins regardless of their affinity to serpines. Moreover, the effect of TFPI released on clotting processes is also measured. Thus, the PiCT test provides a physiologically relevant anticoagulant index.

Thrombin Generation Is a Sensitive Measure of Low Molecular Weight Heparin Anticoagulant Activity.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1099-1099
Author(s):  
Alexander Gatt ◽  
Anne Riddell ◽  
Lesley Lanning ◽  
Saman Aghighi ◽  
Pamala Kanagasapathy ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Thrombin Generation ◽  
Conflicts Of Interest ◽  
Anticoagulant Activity ◽  
Coagulation Cascade ◽  
Low Molecular Weight ◽  
Acute Thrombosis ◽  
Coagulation Proteins ◽  
Risk Patients ◽  
The Individual

Abstract Abstract 1099 Current guidelines recommend monitoring of low molecular weight heparins (LMWHs) using the anti-Xa assay in high risk patients like those with renal impairment, pregnancy or overweight and in children. However, it is well accepted that this test does not accurately predict the anticoagulant effect of these drugs1. This is understandable since the various LMWHs available affect the coagulation cascade in different ways relative to their different molecular structure. Notoriously, the larger LMWHs like Tinzaparin have a higher anti-IIa to anti-Xa ratio that is not detected by the anti-Xa assay. We hypothesized that thrombin generation (TG) is a better, more sensitive way how to monitor LMWH anticoagulant activity since it is a measure of the interplay of all coagulation proteins. Blood samples from patients with acute thrombosis, pregnancy and other conditions and having LMWH monitoring were analysed using a chromogenic anti-Xa assay and a TG assay as per Hemker et al2 together with a chromogenic anti-IIa and FVIII clotting assay (FVIII:C). A tissue factor trigger of 10pM Innovin was used for the TG experiments. Patient samples were divided into 2 groups: those on Tinzaparin (n=45) or Enoxaparin (n=39). There was no difference between the FVIII:C levels of the Tinzaparin and Enoxaparin groups (mean 250 vs 327IU/ml P>0.05). A higher lower mean anti-Xa and a higher mean anti-IIa level was achieved with Tinzaparin (0.48 vs 0.63 U/ml P= >0.05 for anti-Xa and 0.3 vs 0.15U/ml P=0.005 for anti-IIa respectively). The endogenous thrombin potential (ETP) was significantly lower with Tinzaparin than Enoxaparin despite a higher anti-Xa (705 vs 1216nM.min P=0.006). Linear regression analysing TG with anti-Xa of the two LMWHs shows that 1.0U/ml antiXa activity for Enoxaparin is as potent as 0.7U/ml Tinzaparin in suppressing TG to similar levels. Significant inter-individual variation in TG suppression was noted with both LMWHs. This study demonstrates that anti-Xa results achieved for different LMWHs do not have the same anticoagulant significance. Using TG, we achieved similar therapeutic anti-Xa levels as achieved from the individual LMWH clinical trials3. It is clear that TG is a better test to predict LMWH anticoagulant activity. This needs to be proven in clinical studies. 1. Baglin T et al British Journal of Haematol. 2006; 133(1): 19–34. 2. Hemker HC et al Pathophysiol Haemost Thromb, 33, 4-15. Boneu B and de Moorloose P. Semin Thromb Hemost 2001; 27(5): 519–522. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Exploring the Critical Factors Limiting Polyaniline Biocompatibility

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 362 ◽  
Author(s):  
Věra Kašpárková ◽  
Petr Humpolíček ◽  
Jaroslav Stejskal ◽  
Zdenka Capáková ◽  
Patrycja Bober ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Flow Cytometry ◽  
Cell Death ◽  
Ammonium Persulfate ◽  
Low Molecular Weight ◽  
Synergic Effect ◽  
Critical Factors ◽  
Aniline Hydrochloride ◽  
Crucial Information ◽  
The Individual

Today, the application of polyaniline in biomedicine is widely discussed. However, information about impurities released from polyaniline and about the cytotoxicity of its precursors aniline, aniline hydrochloride, and ammonium persulfate are scarce. Therefore, cytotoxicity thresholds for the individual precursors and their combinations were determined (MTT assay) and the type of cell death caused by exposition to the precursors was identified using flow-cytometry. Tests on fibroblasts revealed higher cytotoxicity of ammonium persulfate than aniline hydrochloride. Thanks to the synergic effect, both monomers in combination enhanced their cytotoxicities compared with individual substances. Thereafter, cytotoxicity of polyaniline doped with different acids (sulfuric, nitric, phosphoric, hydrochloric, and methanesulfonic) was determined and correlated with impurities present in respective sample (HPLC). The lowest cytotoxicity showed polyaniline doped with phosphoric acid (followed by sulfuric, methanesulfonic, and nitric acid). Cytotoxicity of polyaniline was mainly attributed to the presence of residual ammonium persulfate and low-molecular-weight polar substances. This is crucial information with respect to the purification of polyaniline and production of its cytocompatible form.

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