Characterization of amino acid and glutathione adducts of cis-2-butene-1,4-dial, a reactive metabolite of furan

Metabolic activation of the hepatocarcinogen furan yields metabolites that react covalently with proteins. cis-2-Butene-1,4-dial is a microsomal metabolite of furan. This reactive aldehyde is thought to be the toxic metabolite that is responsible for the carcinogenic activity of furan. In order to characterize the chemistry by which this unsaturated dialdehyde could alkylate proteins, the products formed upon reaction of cis-2-butene-1,4-dial with model nucleophiles in pH 7.4 buffer were investigated. N(alpha)-Acetyl-L-lysine (AcLys) reacts with cis-2-butene-1,4-dial to form N-substituted pyrrolin-2-one adducts. N-Acetyl-L-cysteine (AcCys) reacts rapidly with cis-2-butene-1,4-dial to form multiple uncharacterized products. The inclusion of AcLys in this reaction mixture yielded an N-substituted 3-(S-acetylcysteinyl)pyrrole adduct which links the two amino acid residues. Related compounds were isolated when cis-2-butene-1,4-dial and glutathione (GSH) were combined. In this case, cis-2-butene-1,4-dial cross-linked two molecules of GSH resulting in either cyclic or acyclic adducts depending on the relative GSH concentration. Incubation of furan with rat liver microsomes in the presence of [glycine-2-3H]GSH led to the formation of radioactive peaks that coeluted with synthetic standards for the bisgluthathione conjugates. These studies demonstrate that the reactive cis-2-butene-1,4-dial formed during the microsomal oxidation of furan reacts rapidly and completely with amino acid residues to form pyrrole and pyrrolin-2-one derivatives. Therefore, this metabolite is a likely candidate for the activated furan derivative that binds to proteins. The ease with which cis-2-butene-1,4-dial cross-links amino acids suggests that pyrrole-thiol cross-links may be involved in the toxicity observed following furan exposure.     

Structural aspects of glucans formed in solution and on the surface of hydroxyapatite

Streptococcus mutans glucosyltransferases (GtfB, -C, and -D) and their products formed from sucrose, glucans, play an essential role in the pathogenesis of dental caries. Enzymatically active Gtf is found in whole human saliva (solution), and incorporated into the salivary pellicle that is formed on teeth in vivo (surface). GtfB glucans are predominantly 1,3-linked; however, surface-formed glucans from GtfB contain greater amounts of 3-linked glucose than glucans formed in solution. In contrast, the major linkage of glucans formed on the surface by GtfB in the presence of sucrose and starch hydrolysates in 4-linked glucose. GtfC-derived glucans in solution have a major linkage of 6-linked glucose, while surface-formed glucans from the same enzyme have 3-linked glucose as the major linkage. GtfD glucans formed either in solution or on the surface are predominantly 1,6-linked; however, surface-formed glucans contain more 6-linked glucose than solution-formed glucans. Digestion with the glucanohydrolases mutanase and dextranase shows differences in susceptibility among glucans formed either in solution or on the surface by each of the Gtf enzymes, and differences are also seen in the soluble end products from these digestions. Our results show that the same Gtf enzyme can form structurally distinct glucans in solution and on a surface. These observations are important in the study of naturally occurring microbial films.     

Dietary inulin lowers plasma cholesterol and triacylglycerol and alters biliary bile acid profile in hamsters

The mechanisms by which inulin may elicit its lipid-lowering effect are not well elucidated. To examine the lipid-lowering potential of inulin and especially its effect on bile acid metabolism, male golden Syrian hamsters were fed semipurified diets containing 20 g/100 g fat, 0.12 g/100 g cholesterol and 0 (control), 8, 12 or 16% inulin for 5 wk. Plasma total cholesterol concentrations were significantly lowered by 18, 15 and 29% in hamsters fed 8, 12 and 16% inulin, respectively. Dietary inulin specifically decreased VLDL cholesterol, which was significantly lower in hamsters fed 16% inulin compared with controls (1.1 +/- 0.3 vs. 2.9 +/- 0.6 mmol/L). LDL and HDL cholesterol were not significantly affected by dietary inulin. Plasma triacylglycerol was significantly reduced by 40 and 63% in hamsters fed 12 and 16% inulin, respectively. Hepatic total cholesterol and particularly esterified cholesterol accumulation were significantly lower in hamsters fed 8% inulin compared with controls. All three levels of dietary inulin caused distinct alterations in the bile acid profile of gallbladder bile. Taurochenodeoxycholic acid was significantly lower, whereas glycocholic and glycodeoxycholic acid were greater in hamsters fed inulin. Daily fecal bile acid excretion (micromol/d) tended to be greater (P = 0.056) in inulin-fed hamsters compared with controls, whereas daily neutral sterol excretion was not affected. These data demonstrate that the lipid-lowering action of inulin is possibly due to several mechanisms, including altered hepatic triacylglycerol synthesis and VLDL secretion and impaired reabsorption of circulating bile acids.     

Increases in hematopoietic responses caused by beta-glucans in mice

The effects of various (1-->3)-beta-D-glucans on hematopoietic responses of mice were investigated by measuring colony stimulating activity in sera and ascites of the mice administered glucan. We have demonstrated that the hematopoietic response was increased by various structures of (1-->3)-beta-D-glucans, i.e. soluble glucans (linear, branched, single helix, triple helix) and particulate glucans. From the viewpoint of structure and activity relationships, we found several characteristic features: i) hematopoietic response induced by the particulate glucan disappeared faster than that by the soluble glucans, ii) conformation of the glucans, single vs. triple helix, are relatively independent of the response, iii) linear glucan had a weaker response, and iv) there is a strong strain-dependency of the response. These results corresponded well with the fact that branched (1-->3)-beta-D-glucans, but not linear and not particulate, are often used as biological response modifiers for cancer patients.     

Predictability of creatinine clearance estimates in critically ill patients

OBJECTIVES: a) To evaluate the predictive ability of different creatinine clearance methods as compared with the criterion standard, inulin clearance; and b) to determine which of the predictive methods yields the most accurate estimation of creatinine clearance. DESIGN: Prospective study. SETTING: Medical intensive care unit (ICU) of a university-affiliated tertiary care hospital. INTERVENTIONS: Glomerular filtration rate was measured by the criterion standard, inulin clearance. PATIENTS: Twenty mechanically ventilated adults. MEASUREMENTS: Renal function was assessed by the following procedures: inulin clearance using a standard protocol, 30-min creatinine clearance, 24-hr creatinine clearance, and creatinine clearance estimates by the Cockcroft-Gault equation. Ideal body weight, total body weight or lean body mass with actual serum creatinine or serum creatinine concentration corrected to 1 mg/dL (85 mumol/L) in cachectic patients were sequentially incorporated into the Cockcroft-Gault equation. RESULTS: The Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration, was the best predictor of inulin clearance with the smallest bias (9.7 +/- 8.6, 95% confidence interval 5.7 to 13.8). The bias encountered with the 30-min creatinine clearance was not different from that value with the 24-hr creatinine clearance (21.6 +/- 33.0, 95% confidence interval 6.2 to 37.1 vs. 25.4 +/- 28.3, 95% confidence interval 11.8 to 42.9). Good correlations existed between inulin clearance and the Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration (r2 = .81; p = .0001), as well as between inulin clearance and the Cockcroft-Gault equation, using the lower of ideal or total body weight and the higher of the actual serum creatinine concentration or corrected serum creatinine (r2 = .75; p = .0001). The 30-min creatinine clearance and the 24-hr creatinine clearance had poorer agreement with inulin clearance. The incorporation of a corrected serum creatinine value into the Cockcroft-Gault equation consistently led to better predictions and higher correlation coefficients. CONCLUSIONS: The utilization of the Cockcroft-Gault equation as used clinically (the lower of ideal or total body weight and the higher of actual serum creatinine or corrected serum creatinine concentration to 1 mg/dL [85 mumol/L]) results in more accurate predictions of glomerular filtration rate in the medical, critically ill patient than urine creatinine clearance measures. If creatinine clearance measures are used, the 30-min collection provided results not different from those results obtained with 24-hr urinary collections.     

Helium-oxygen improves Clinical Asthma Scores in children with acute bronchiolitis

Sprague-Dawley rats (n = 32) were fed diets without fiber (control) or containing 1 or 5% chicory extract or 5% inulin for 4 wk; 0.2% cholesterol was added to all diets. Rats fed chicory extract and inulin diets had significantly higher serum high density lipoprotein (HDL) cholesterol and generally lower low density lipoprotein (LDL) cholesterol concentrations, thus significantly greater ratios of HDL/LDL cholesterol compared with the controls (P < 0.05). The serum apolipoprotein B/apolipoprotein A-1 ratio was significantly lower in rats fed diets containing chicory extract or inulin than that in rats fed fiber-free diets, due to significant reductions in apolipoprotein B concentration (P < 0.05). Greater liver lipid and triglyceride concentrations were observed in rats fed chicory extract or inulin diets compared with the controls (P < 0.05). However, liver phospholipid and cholesterol concentrations were not significantly different among groups (P > 0.05). Addition of 5% inulin to the diet resulted in greater cecal weight, whereas both 5% chicory extract and 5% inulin resulted in greater cecal propionic acid concentration compared with the controls (P < 0.05). Rats fed chicory extract and inulin had significantly greater fecal lipid, cholesterol and bile acid excretions than those fed fiber-free diets (P < 0.05). The results of this study suggest that the improved lipid metabolism observed in rats fed chicory extract (mainly inulin component) may be caused by an alteration in the absorption and/or synthesis of cholesterol, which might result from the changes in cecal fermentation, and by an increase in the fecal excretion of lipid, cholesterol and bile acid.     

Cell-associated glucans of Burkholderia solanacearum and Xanthomonas campestris pv. citri: a new family of periplasmic glucans

The cell-associated glucans produced by Burkholderia solanacearum and Xanthomonas campestris pv. citri were isolated by trichloroacetic acid treatment and gel permeation chromatography. The compounds obtained were characterized by compositional analysis, matrix-assisted laser desorption ionization mass spectrometry, and high-performance anion-exchange chromatography. B. solanacearum synthesizes only a neutral cyclic glucan containing 13 glucose residues, and X. campestris pv. citri synthesizes a neutral cyclic glucan containing 16 glucose residues. The two glucans were further purified by high-performance anion-exchange chromatography. Methylation analysis revealed that these glucans are linked by 1,2-glycosidic bonds and one 1,6-glycosidic bond. Our 600-MHz homonuclear and 1H-13C heteronuclear nuclear magnetic resonance experiments revealed the presence of a single alpha-1,6-glycosidic linkage, whereas all other glucose residues are beta-1,2 linked. The presence of this single alpha-1,6 linkage, however, induces such structural constraints in these cyclic glucans that all individual glucose residues could be distinguished. The different anomeric proton signals allowed complete sequence-specific assignment of both glucans. The structural characteristics of these glucans contrast with those of the previously described osmoregulated periplasmic glucans.     

Scavenging activity of furan derivatives against hydroxyl radical generated by Fenton system

As the continuation of the work on the antioxidant properties of furan derivatives, we have studied hydroxyl radical (OH.) scavenging activity of dimethylfuran (DMF) and diphenylfuran (DPF), which are well-known as an effective scavenger of singlet oxygen, by an ESR spin trapping technique. The incubation mixture of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapping agent with FE2+ and H202 in 50% acetonitrile aqueous solution gave 1:2:2:1 line signals characteristic of DMPO-OH spin adduct. The additions of furan derivatives to the incubation mixture decreased the intensity of the DMPO-OH spin adduct signal in a dose-dependent manner. The activities of furan derivatives were in the order of DMF > DPF > furan. The decrease in the intensity of the signals was not due to the inhibition of OH. generating system itself and the destruction of the spin adduct by furan derivatives. By comparison with the common OH. scavengers, DMF and DPF were found to scavenge OH. more effectively than dimethylsulfoxide and mannitol. These results indicate that DMF and DPF can act as a OH. scavenger as well as a singlet oxygen scavenger.     

The occurrence of furan fatty acids in Isochrysis sp. and Phaeodactylum tricornutum

Two algae species with a fundamentally different fatty acid composition were investigated for their furan fatty acid (F-acid) content. Isochrysis sp. contains different F-acids with a pentyl side chain in alpha'-position of the furan ring. In consideration of its fatty acid composition which is predominated by compounds with a C-18 chain, this result supports the assumption that pentyl-F-acids derive from linoleic acid. In contrast, only F-acids with propyl side chain were found in Phaeodactylum tricornutum. The low content of C-18 fatty acids in this diatomae contradicts the previous hypothesis that linolenic acid is the precursor of propyl-F-acids. But the presence of (n - 4) unsaturated fatty acids with 16 carbon atoms in Phaeodactylum tricornutum suggests that propyl-F-acids are synthesized from 9,12-hexadecadienoic acid in a very similar biogenetic pathway than pentyl-F-acids.     

Special features of feeding in ecologic animal husbandry

Food produced in ecological agriculture becomes popular more and more. In the interest of consumers (to protect against deception) and of producers (to contrast with conventionally produced food) it is necessary to define the conditions and circumstances when products can be declared as ecological. Up to now definitions of housing and feeding animals in organic agriculture only are set up by private organizations and associations, but in the future we will have a direction of the European community (Nr. 2092/91 EWG), extended by directives and restrictions focussed on animal husbandry and feeding. Aim of this contribution is to give information on special restrictions on feeds and feeding of food producing animals in organic agriculture (preconditions in the case that labelling as "ecologically produced" is intended). Conventionally produced feedstuffs are restricted, common complete diets and some special feed additives (for example growth promoters) are not allowed. Feeding according to species specific requirements (herbivorous animals) as well as according to age and development (for example minimum duration of suckling periods) is intended. On the other hand there is a conscious renunciation of maximizing animals' performance (and plant yields). Consequences, risks and conflicts of different aims in feeding in accordance with ideas of organic agriculture are discussed. Various efforts at sustainability of conventional agriculture are influenced markedly by ideas and concepts established in organic agriculture primarily.     

Characterization of a strictly specific acid beta-galactosidase from Achatina achatina

An acid beta-galactosidase was isolated from the digestive juice of Achatina achatina and purified to homogeneity by anion exchange, gel-filtration and hydroxyapatite chromatographies. This enzyme is soluble, as are the cytosolic beta-galactosidases, functions at acid pH like the lysosomal enzymes but differs from the other soluble animal beta-galactosidases in that it is highly specific for the beta-D-galactosyl residue. In addition, it cleaves the beta1-4 linkage much faster than the beta1-3 and beta1-6 linkages. The enzyme is a monomeric glycoprotein with a molecular mass of 120-125 kDa and the carbohydrate moiety makes up approximately 6% (w/w) of the protein. The amino acid composition displays an important amount of acidic/amide and hydroxy amino acid residues and a low content of basic residues. The enzyme activity is markedly affected by the ionic strength of the medium and the rate-pH curve was shifted towards higher pH values in the presence of added salt. Acid beta-galactosidase is capable of catalysing transgalactosylation reactions. The yields of galactosylation of hydroxy amino acid derivatives, catalysed by the enzyme in the presence of lactose as the glycosyl donor, were higher than those reported previously with conventional sources of beta-galactosidases. In addition, the pH optimum is different for the hydrolysis (pH 3.2) and transgalactosylation (pH 5.0) reactions. On the basis of this work, the enzyme could be used as a tool in the structural analysis of D-galactose-containing oligosaccharide chains, as well as for the synthesis of glycoconjugates.     

Microsurgical pterional approach to aneurysms of the basilar bifurcation

The ultrastructure and component polysaccharides of the cell wall of Pythium debaryanum IFO-5919 were investigated. From results obtained by means of acid, alkali, Schweitzer reagent and beta-1, 3-glucanase treatments and electron microscopy, it was concluded that 1) the acid-extracted fraction was a 1,3-linked branched glucan, 2) the alkali-extranded fraction was a mixture of 1,3-, 1,6-, and 1,3,6-linked highly branched two glucans, 3) the Schweitzer reagent-extracted fraction was a beta-1, 4-linked glucan, 4) the cell wall was constructed from two types of cullulosic microfibrils, as a frame and as a finer network, and amorphous beta-1, 3-glucan including beta-1, 6-linkage, 5) cellulosic microfibrils were covered by matrix material consisting of a mixture of amorphous beta-1, 3-linked and beta-1, 6-linked branching glucans.     

Operation at High Pellet Ratio and Without External Slag Formers – Trials in an Experimental Blast Furnace

Blast furnaces that operate with pellets and sinter normally use high basicity sinter and acid pellets to balance the slag chemistry. When external additives are used, irregular slag formation occurs due to their uneven distribution in the burden. If basic sinter is used together with a large amount of acid pellets, all additives are incorporated in the iron bearing materials with an improved burden mixture as a consequence. During a campaign in the LKAB Experimental Blast Furnace, pellets and sinter were operated at an ultra low slag volume. A high amount of pellets was balanced with high basicity sinter. An improved blast furnace operation is shown when operating at ultra low slag volume and without external slag formers. During the test period, the blast furnace operation was smooth and stable, and the reductant rate was decreased.     

Studies on the reductive amination of 3-deoxy-D-manno-octulosonic acid (Kdo)

Reductive amination of 3-deoxy-D-manno-octulosonic acid (Kdo) with allylamine (AIIN) or 2-(4-aminophenyl)ethylamine (APEA) yields epimer pairs of 2-N-allylamino and 2-N-[2-(4-aminophenyl)ethylamino]-2,3-dideoxy-D-glycero-D-galacto- and -2,3-dideoxy-D-glycero-D-talo-octonic acid. The yields were 50-60% due to reduction of Kdo to the respective polyols as side reaction products. Mass spectrometric analyses proved the amination derivatives to be the expected glycamines. Nuclear magnetic resonance (NMR) studies were performed on 2-N-allylamino-2,3-dideoxyoctonic acid which represents the chain terminus of allylaminated oligosaccharides derived from bacterial lipopolysaccharides (LPS) after acid hydrolysis and reductive allylamination.     

Abnormal c-fos expression in the lateral habenula during dystonic attacks in a hamster model of idiopathic dystonia

Synthetic sulfated bis-lactobionic acid amides are important heparin-like pharmaceuticals. The synthesis of these compounds yields molecules differing in the number of sulfate groups, and, during the isolation procedure, the required species may partially decompose or take in some impurities. This article shows that capillary zone electrophoresis may serve well as an expedient method for the analysis of the above-mentioned pharmaceuticals. Complex-forming equilibria between the analytes and bivalent cations present in the background electrolyte bring selectivity necessary for the separation, and the detection at various wavelengths serves as an aid in the characterization of admixtures, decomposition products, and impurities. Capillary isotachophoresis may also be used for the analysis of these species, bringing about the potential of micropreparation of individual compounds and opening the chance for continuous free-flow electrophoresis.     

Measurement of glomerular filtration rate by the 99mTc-DTPA renogram is less precise than measured and predicted creatinine clearance

The work was devised to compare measurements of glomerular filtration rate (GFR) by technetium-99m-diethylenetriaminepentacetic acid (99mTc-DTPA) renogram to those by creatinine clearance (measured and predicted by Cockroft and Gault) and by inulin clearance. A total number of 65 individuals were enrolled: 15 healthy controls and 50 patients with renal disease. Compared to inulin clearance used as the gold standard, 99mTc-DTPA overestimated at low and underestimated at high GFRs. 99mTc-DTPA measurements were less precise than creatinine clearance except for individuals with GFR >100 ml/min x 1.73 m2. Measured creatinine clearance had the highest correlation coefficient with inulin clearance, 99mTc-DTPA clearance the lowest. In correlation analyses, 81.5% of the interindividual variability for measured creatinine clearance could be explained by true differences in inulin clearance; this value dropped to 59.1 and 57.4% for predicted creatinine clearance and 99mTc-DTPA, respectively. In patients with GFR <25 ml/min x 1.73 m2, all 99mTc-DTPA measurements were out of the 95% confidence interval for the inulin measurement. It can be inferred that 99mTc-DTPA clearance from the renogram is less precise than measured and predicted creatinine clearance.     

Computer-aided stochastic modeling of the radiolysis of liquid water

A computer-aided stochastic model of the radiolysis of liquid water has been developed. It is based on Monte Carlo simulation of charged-particle tracks, a random-flight method to simulate diffusion of species and the Debye-Smoluchowski theory of reactions between radicals. The model takes into account the formation of ionizations, excitations and subexcitation electrons at the physical stage. The corresponding initial yields at approximately 1 fs were found to be G(ion) = 4.37, G(exc) = 2.81 and G(e-sub) = 4.38. The energy spectrum of subexcitation electrons has been calculated. Autoionizations and dissociations of excited molecules, hole migration, electron thermalization, geminate recombination and the cage effect are considered at the physico-chemical stage. The mean thermalization distance of subexcitation electrons is 24.5 nm. The initial yields of e(aq)-, H+, OH, H, H2 and O are 4.89, 4.86, 5.96, 1.10, 0.15 and 0.15, respectively. The reactions between radicals and products as well as their diffusion are simulated at the chemical stage. The decay kinetics of the most important radicals is reported together with the time evolution of the most important reactions. The yields of the reactive radicals, e(aq)-, H+, OH, H and OH-, at 1 ps are 4.84, 4.85, 5.87, 1.09 and 0.0, respectively. The respective steady-state yields at 10 micros are 2.70, 3.58, 2.89, 1.17 and 0.79. The yields of molecular products, H2O2 and H2, are 0.73 and 0.47 at 10 micros. The concentration-dependent yields of e(aq)-, OH and H2O2 are calculated in three different aqueous solutions. The predictions of the model agree fairly well with experimental data.     

Recovering REEs from NdFeB wastes with high purity and efficiency by leaching and selective precipitation process with modified agents

A leaching and selective precipitation approach is proposed in this work to recover rare earth elements (REEs) from NdFeB magnet wastes collected from industry. Hydrochloric acid and oxalic acid were employed as the leaching and precipitation agents, respectively. Hexamethylenetetramine (HMTA) or tartaric acid was used as the chelating agent during leaching. Both leaching and precipitation processes were optimized individually. For leaching process, the effects of two different chelating agents, the concentrations of leaching agent, chelating agent, and temperature on the extraction and recovery yields were investigated. The optimized process based on the factorial experiment was determined to be the hydrochloric acid concentration of 6 mol/L, the tartaric acid concentration of 50 g/L, and the temperature of 313 K, by which the extraction yields of Fe and REEs up to 67.99% and 99.27%, respectively, are obtained. For the precipitation process, the optimized oxalic acid dosage and pH value were also determined. The produced RE oxide products have the purity and recovery yield up to 95.83% and 90.18%, respectively. These results indicate that the present method with low acid consumption and high product purity has advantages over many other approaches for REE recovery.     

Largescale Preparation of Organic-Dispersible Lanthanide Fluorides Nanocrystals via Colloid-Extraction Route

Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large Scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.