Effect of the growth-stimulating bacterium <i>Pseudomonas protegens</i> DA1.2 and its metabolites on damage to rapeseed by soil residues of metsulfuron-methyl

An extract of Ascaris suum perienteric fluid was fractionated on Sephadex G-200 and the resulting high molecular weight (approx. 600,000 daltons) and low molecular weight (approx. 16,000 daltons) fractions examined for allergenicity using human sera. Radioallergosorbent (RAST) and RAST-inhibition assays showed that the high molecular weight fraction was 15- to 40-fold more potent than the low molecular weight fraction. Crossed radio-immunoelectrophoretic analysis showed that the high molecular weight fraction contained 10 allergens in contrast to the 6 comprising the low molecular weight fraction. Polyacrylamide gel electrophoretic studies in combination with RAST indicated that two high molecular weight glycoprotein-staining components may be major allergens. A. suum cross-reacted allergenically with Toxocara canis and various life cycle stages of Nippostrongylus brasiliensis but not with Strongyloides ratti or Schistosoma mattheei. The cross-reacting allergens were predominantly of high molecular weight and the molecular weight distribution pattern obtained for A. suum, T. canis and N. brasiliensis paralleled that obtained for the distribution of the carrier of the hapten phosphorylcholine (Pc). However, it was shown that the hapten per se was not allergenic. In contrast, analysis of the allergens from N. brasiliensis using sera from rats infected with the same parasite showed that the homologous allergens were predominantly of low molecular weight (approx. 20,000 daltons) and did not contain Pc.

203Hg binding in the liver and kidney of the frog, Rana tigrina

The biological and immunological properties of fractionated atrial extracts from young and old rats

The application of HPLC–SEC for the simultaneous characterization of NOM and nitrate in well waters

Porcine intestinal mucosal heparin induced aggregation of platelets in citrated platelet-rich plasma and enhanced platelet aggregation and serotonin secretion induced by other agents. This action of heparin was blocked by substances that elevate platelet cyclic AMP and by EDTA but not by inhibitors of platelet cyclooxygenase. The effect was not inhibited by apyrase or by N-amylthio-5'-AMP and therefore did not require the action of ADP, nor was there activation of platelet phospholipase. Platelet aggregation by heparin required a plasma cofactor different from the cofactor required for ristocetin. Fractionation of heparin yielded preparations that varied in molecular weight and, within a given molecular weight fraction, in affinity for antithrombin III. Fractions of high molecular weight (average 20,000) were more reactive with platelets than were fractions of low molecular weight (7,000). Anticoagulant activity did not parallel the platelet reactivity of heparin fractions. Among high molecular weight fractions, preparations of high or low antithrombin affinity were equally active in induction of platelet aggregation. In low molecular weight fractions, there was an inverse relationship between platelet reactivity and anticoagulant activity in normal platelet-rich plasma, but, in platelet-rich plasma depleted of antithrombin, low molecular weight fractions of high and low antithrombin affinity reacted equally with platelets. These results suggest that formation of an antithrombin-heparin complex protected platelets from aggregation by heparin. Selection of heparin fractions of low molecular weight and high antithrombin affinity may improve anticoagulant therapy and development of thromboresistant heparin-coated artificial materials.

Long-term aging of bitumen causes formation of oxidation products that can be associated with polar and strongly interacting functional groups leading to a tremendous influence on bitumen properties. This can lead to an aggregation of the most polar molecules in the asphaltene fraction. Other types of aggregation have also been described in the literature, with larger and more aliphatic compounds through wax interactions. These aggregate phases can be studied using gel permeation chromatography (GPC) for the separation of heavy petroleum products based on their molecular weight. Three molecular weight fractions of native bitumen and its aged state by a long-term pressure aging vessel (PAV-72h) were obtained with low molecular weight (LMW), medium molecular weight (MMW), and high molecular weight (HMW) fractions. To characterize oxidative aging on each fraction at the molecular level, Fourier transform ion cyclotron resonance (FTICR) was used. Indeed, the ultrahigh resolution and mass accuracy of this analyzer allow to attribute molecular formulas to each signal of complex matrices unambiguously. An electrospray ionization (ESI) source was used to selectively ionize acid molecules, while atmospheric pressure photoionization source (APPI) was used to have a nonselective ionization of low polarity molecules from bitumen. With both ionization sources, the LMW fraction exhibited the most aromatic and heteroelement-enriched molecules. In terms of variation with aging, the LMW fraction showed the most pronounced variations. Molecular maps evidenced the occurrence of low DBE oxidation markers for Oz and OzSy families. Low variations were observed on distributions of MMW and HMW fractions. Concerning HMW, these unexpected results, obtained by ESI and APPI ionization sources, may be due to a protection of the molecules against oxidation within aggregates. In addition, APPI results underlined that the higher molecular weight distribution containing most of the aggregate molecules was mainly composed of large aliphatic molecules. Overall, this study demonstrated that oxidation products corresponded to small and aliphatic molecules majorly found in the LMW fraction and that aggregated molecules form HMW fraction were relatively protected from oxidation.

Blood plasma from tumor-bearing rats was incubated with 67Ga-citrate, and two fractions of high molecular weight (proteins) and low molecular weight were isolated by dialysis and by gel-filtration chromatography. Both fractions showed a different in vivo uptake by DS-sarcoma-bearing animals, the high molecular weight fraction being accumulated to a lesser extent. Compared to 67Ga-citrate the low molecular weight fraction showed a different uptake which for most tissues was significatively higher. This behavior suggests the presence of 67Ga in chemical forms other than citrate in the low molecular weight fraction. The lower uptake of the blood protein fraction is discussed.

Since a great quantity of dissolved Hg in natural waters was shown to be bonded onto colloidal organic matter (COM), Hg speciation, transport, biological availability and cycling are affected by interactions between Hg and COM. They are in large proportion dependent on the chemical composition and structure of COM. Macroaggregates (macrogels), produced episodically in the northern Adriatic by agglomeration of dissolved organic macromolecules—mostly heteropolysaccharides—of prevalently phytoplankton (diatom) origin, offer a rare opportunity to study these topics. The chemical speciation of macroaggregate Hg in the Gulf of Trieste (northern Adriatic Sea) was studied using filtration and centrifugation discriminating between matrix (water insoluble) and interstitial water (water soluble) colloidal fraction. The colloidal fraction was subsequently ultrafiltered through membranes with a nominal pore size of 30, 10 and 5 kDa cutoff sequentially (in a cascade fashion), and fractions analyzed for carbohydrate, Corg. and Ntot. contents, and FTIR. The highest carbohydrate content and the lower Corg./Ntot. ratio were associated with higher molecular weight (MW) fraction (>30 kDa) suggesting that aminopolysaccharides and glycoproteins can be important constituents of this fraction. Analyses of MW of permeates, assayed by high-pressure size exclusion chromatography (HPSEC), revealed that they are composed of macromolecules of a rather narrow MW distribution. Analyses of Hg concentrations revealed the highest concentration in high MW fraction in connection with the highest content of organic N constituents. This scenario was confirmed during a degradation experiment showing the preservation of Hg associated with higher MW fraction containing organic N constituents. Conversely, Hg in lower MW fractions, composed mostly of carbohydrates and subjected to degradation, is released into solution. The higher Hg concentration and lower Hg/Corg. ratio observed in matrix, characterized by the important presence of lipids in addition to polysaccharides and proteins, suggests the possible interaction between macrogel and HgS particles originating from Idrija (NW Slovenia) mining district.

The synthesis of a 70,000 dalton-heat shock protein (hsp70) is one of several heat shock proteins induced in HeLa cells during the incubation in medium containing zinc sulphate. The synthesis of hsp70 was increased in the presence of 200 microM zinc sulphate and above, but not at 100 microM zinc sulphate. On the other hand, the synthesis of metallothionein was activated in the presence of 100 microM zinc sulphate and above. Uptake of zinc into the cells depended on the concentration of zinc sulphate in the medium. The separation of intracellular zinc into three fractions by gel filtration chromatography; high molecular, metallothionein, and low molecular fractions, showed that zinc in the low molecular weight and metallothionein fractions was elevated in the presence of 100 microM zinc sulphate in the medium, whereas increase in the zinc content of the high molecular weight fraction occurred at 200 microM zinc sulphate and above. Inhibition of cell growth and cellular protein synthesis was also observed at 200 microM zinc sulphate and above, but not at 100 microM. From these findings, since the induction of hsp70 synthesis and inhibition of cell growth occurred concomitantly with the increase of zinc in the high and low molecular weight fractions, hsp70 seemed not to function in the detoxification of zinc, but it may participate in the repair of zinc-induced damage.

The foam stability of beer is impacted by positive and negative forces that counteract each other. A series of beers was investigated to assess whether foam performance was primarily impacted by the level of foam-promoting polypeptide or by the presence of inhibitory lipids. The studies involved ultrafiltration of beers and comparison of the foam stability of a standard protein (egg albumin) when foamed in the ultrafiltrates, the retentate, a reference alcohol solution, and the native beer. In all cases, the foam stability of the beers was boosted by adding protein, and there was also evidence of foam-inhibitory material in both the low and high molecular weight fractions. Hydrolysis studies with papain generated some evidence that there may be low molecular weight peptide material that is foam negative. Experiments in which beers and ultrafiltration fractions were treated with an immobilized lipid-binding protein confirmed there are foam-damaging lipids in both the high and low molecular weight fractions from beer. Improved foam performance of commercial beers demands attention both to boosting foam-promoting polypeptide levels and to attending to lipids and lipid oxidation throughout the process.

Currently, elemental chlorine-free (ECF) and totally chlorine-free (TCF) bleaching systems are widely used for pulp production. Low and medium molecular weight lignin break-down products are known to have harmful effects on the environment. According to some recent results, also high molecular weight (HMW) material consisting mainly of lignin and carbohydrates may cause toxic effects to the environment. For these reasons, toxicity and structure studies of HMW materials are of great importance. This investigation is a part of a larger project to obtain more structure information of HMW materials and toxicity of ECF and TCF bleaching effluents. Size-exclusion chromatography (SEC) has been commonly used for the characterization of organic macromolecules such as lignin, but to our knowledge, no reports have appeared dealing with the comparison of SEC of ECF and TCF bleaching liquors. The aim of the present study was to get more information about the molecular weight distribution (MWD) of HMW fractions of waste liquors from ECF and TCF bleaching sequences by SEC. The MWDs of organic materials dissolved during different stages of ECF bleaching (O-D-EOP-D-ED) and TCF bleaching (O-Z-Q-P-Z-Q-P-P) of softwood (Pinus sylvestris) kraft pulp were determined and compared by SEC. All effluent samples from the above bleaching stages were ultrafiltrated using a membrane with a cutoff value of 1,000Da. SEC was performed on high and also low molecular weight fractions and non-fractionated effluents. In the SEC experiments, a Superdex 75 column was used with 0.1M NaOH solution as the eluent. Standards used for calibrating the SEC system were albumin, carboanhydrase, cytochrome C, tannic acid, dehydrodiacetovanillone, and vanillin. The chromatograms of liquors from TCF bleaching stages vary more than those from ECF bleaching. Peroxide and chelating stages contained mostly high molecular weight (HMW) matter whereas chlorine dioxide and ozone stages had more low molecular weight compounds. The lignin content in HMW matter was higher than in stages that consisted of low molecular matter. Bleaching effluents contained the highest amounts of HMW material, mainly lignin, in the beginning of the sequences; the amounts decreased towards the end of the bleaching sequence. Determinations of MWD by the SEC method showed that effluents from the TCF sequence contained more HMW material than those from the ECF stage. This might be due to peroxide stages (P) that dissolve HMW lignin effectively. However, the molecular weights of ozone stages (Z) were very low compared to other stages. Chlorine dioxide stages also dissolved mostly low molecular weight lignin. Ultrafiltration of bleaching liquors showed that high molecular weight fraction also included some low molecular weight compounds and vice versa. High polydispersity and high lignin content correlated with the amount of HMW material in ECF and TCF bleaching stages. Our liquor samples were studied by using a UV detector commonly used for lignin preparations; in upcoming investigations, it will be interesting to determine carbohydrates such as hemicelluloses. The results are applicable in papermaking in order to improve commonly used bleaching procedures, to test new potential bleaching systems, and to study chemical behavior of HMW materials in various bleaching liquors. The present results also form a good basis for toxicity measurements of ECF and TCF bleaching effluents and for more comprehensive spectroscopic and chromatographic experiments with samples taken from various bleaching stages. From the behavior of liquors studied, it appears that our other structure investigations by spectroscopic and chromatographic (NMR, Py-GC/MS, etc.) methods mostly correlate well with the present results.

Soil humic acid was fractionated on a molecular weight basis either using Sephadex gel filtration or electrophoresis on a discontinuous polyacrylamide gel. Low and high molecular weight fractions obtained by these two methods were choosen for subsequent subfractionation using electrophoretic methods. The high and low molecular weight fractions yielded several subfractions after separation by isotachophoresis or isoelectric focusing. Components of the high molecular weight fractions occupied the upper portion of the mobility train; components of the low molecular weight fractions lead the mobility train. Adsorption by Sephadex was avoided by using 4M urea as an eluent. The elution of the humic substances adsorbed to the polyacrylamide gel matrix was achieved by using a 0.1M Tris −0.025M EDTA solution.

To determine the allergens of mite allergic rhinitis, we studied 31 patients with mite allergic rhinitis by skin tests and nasal provocation tests (15 for skin and 16 for nasal tests) using 6 fractions of Dermatophagoides pteronyssinus (Dp) extract differing in molecular weights (15, 25, 32, 53, 95 and 190 kDMW). In skin testing, patients showed intense positive reactions to the fractions of 15, 25, 32, 95 and 190 kDMW, among which the most patients showed positive reactions to the fractions of 15 and 25 kDMW. Significant differences were found in patients' positive reactivity among each fraction and between low (15 and 25 kD) and high (95 and 190 kD) molecular weight fractions as well. In nasal provocation tests, patients showed intense positive reactions to the fractions of 15, 32, 53 and 95 kDMW, especially to the fractions of 15 and 95 kDMW. Furthermore, the insidence of positive reactions to the 15 kDMW fraction was significantly higher than that to any other fraction in the skin tests (P < 0.05). From these results, the low molecular weight fraction, 15 kDMW, is considered to be the main allergen of this mite and the high molecular weight fractions, 95 and 190 kDMW, may also be considered to be allergens of this mite.

1. Young female Wistar rats were fed for 18 d on diets containing dextrose, 43 dextrose equivalent (DE) glucose syrup, fractions of 43 DE glucose syrup of high and low molecular weight or sucrose.2. All rats gained weight and showed no gross external abnormalities or significant dental caries scores.3. The concentrations of cholesterol, triglycerides, free fatty acids and glucose were determined in samples of liver and serum. Generally, these values tended to increase with increasing molecular weight of dietary carbohydrate in the order dextrose, glucose syrup fraction of low molecular weight, and glucose syrup fraction of high molecular weight.4. Rats given the high-molecular weight glucose syrup fraction were found to have caecums twice the normal size.

This article evaluates the H2O2/UV process for the removal of color and dissolved organic carbon (DOC) from textile effluent samples in a batch UV photoreactor. Experimental variables studied include pH, hydrogen peroxide dosage, oxidation time, and UV intensity. Results show that the H2O2/UV process showed better removal of DOC and color at pH 4 than at pH 7, suggesting that the pH should be controlled at both 4 and 7 for color removal, whereas only at 4 for DOC removal. Oxidation time was extended to 30 and 60 min, respectively, which resulted in removal of more than 70% of the color and DOC. Color and DOC removal followed pseudo first-order kinetics and the reaction rate constants increased with increasing both H2O2 dosage and UV intensity. Increase of H2O2 dosage is more efficient than the increase of UV intensity for promoting the treatment performance of the H2O2/UV process. Further, about 80% of DOC with a high molecular weight (MW) fraction was oxidized into DOC with medium and low MW fractions. DOC with low MW fractions predominated more than 60% of the residual DOC. Therefore, the oxidation of DOC with a high MW fraction into medium and low MW fractions was more important than the mineralization of DOC by H2O2/UV oxidation.