Aspartate glucan, glycine glucan, and serine glucan for the removal of cobalt and copper from solutions and brines

Aspartate glucan, glycine glucan, and serine glucan obtained by reductive amination of oxalacetic acid, glyoxylic acid, and beta-hydroxypyruvic acid, respectively, with polyglucosamine were tested as chromatographic chelating media. Crosslinked glycine glucan exhibited high capacities for cobalt and copper, even in acidic solutions (pH 2.9). Breakthrough points for 10 mg/L solutions through 6.0 x 0.6 cm columns containing 200 mg of polymer were at 1.8 L for both ions; for 1 mg/L solutions, they were at 4.0 and 12.0 L for cobalt and copper, respectively. Crosslinked glycine glucan could remove microgram amounts of cobalt and copper from fluoride and chloride brines. Cobalt and copper could be separated by elution with 0.25M sulfuric acid.     

Platelet-activating factor contracts human myometrium in vitro

The myometrial contractile responses to synthetic 1-0-octadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (platelet-activating factor, PAF) and to oxytocin were evaluated in vitro on uterine (lower segment) strips obtained from pregnant women at term (39th week), undergoing elective cesarean section. Contractility was measured isometrically in an isolated organ bath using a superfusion technique. PAF in a concentration range between 5 and 100 nM as well as oxytocin (0.1-10 mU/ml) induced a dose-dependent contraction which could be categorized in two patterns, depending on whether spontaneous activity was present. In resting strips, oxytocin induced a prompt (0.5-1 min) development of active tension, followed by a prolonged (6-18 min), slow contraction and a final relaxation. However, at variance with oxytocin, PAF-induced contractions were rhythmic (3-8/hr), and characterized by a prompt (0.5-2 min) development of tension, followed by a brief (0.5-2 min) plateau, and a final, rapid relaxation. In spontaneously active strips, both stimuli induced a marked potentiation of the contractile activity. PAF response was dependent on both cyclooxygenase- and lipoxygenase-derived products as inferred from the abrogating effects of indomethacin and FPL 55712. A receptor-mediated mechanism of action was inferred from the occurrence of specific desensitization to PAF (but not to oxytocin), and from the blocking effect of CV 3988, a specific PAF receptor antagonist. The present study indicates that PAF stimulates the contraction of human myometrium in vitro and suggests that this mediator may have a role in labor.     

NAD biosynthesis in human placenta: purification and characterization of homogeneous NMN adenylyltransferase.

Nicotinamide mononucleotide (NMN) adenylyltransferase has been purified to homogeneity from human placenta. The purification procedure consists of several chromatographic steps, including dye-ligand, adsorption, and hydrophobic interaction chromatography. The final enzyme preparation is homogeneous as judged by a single silver stainable band on both nondenaturating and denaturating polyacrylamide gels. The native enzyme shows a molecular weight of about 132,000, as determined by gel filtration on a Superose 12 HR 10/30 fast protein liquid chromatography column. The protein possesses a quaternary structure and is composed of four apparently identical M(r) 33,000 subunits. Isoelectrofocusing experiments give multiple pI values ranging from pH 4.7 to 6.6. Optimum pH study shows a plateau extending from pH 6.0 to pH 9.0. Km values for NMN, ATP, NAD+, and PPi are 38, 23, 67, and 125 microM, respectively. Kinetic analysis reveals a behavior consistent with an ordered sequential Bi-Bi mechanism. Among several metabolites tested only ADP-ribose and beta-NMNH were found to significantly inhibit the enzyme activity.     

Regulatory action of prolactin on the in vitro growth of CD34+ve human hemopoietic progenitor cells

The pituitary hormone prolactin (Prl) is known to act as a local regulator of immune cell function, and Prl-binding receptors (Prl-R) have been described to share distinctive features with the members of the newly described cytokine/hemopoietin receptor superfamily. Here we show that the hormone can functionally interact with lineage-specific hemopoietic factors. When highly purified progenitor cells (CD34+ve) were seeded in semisolid methylcellulose cultures in the presence of interleukin (IL)-3, granulocyte-macrophage colony stimulating factor (GM-CSF), and erythropoietin (Epo), a selective enhancing effect of Prl on the formation of colony forming unit-granulocyte (CFU-G) and burst forming unit-erythroid (BFU-E) colonies was observed. The effect of the hormone was plotted as a bell shaped curve, with the optimal response at the supraphysiological concentration of 50 ng/ml. Limiting dilution analysis showed that Prl acted directly on hemopoietic progenitors. This was confirmed by the observation on the CD34+ve cells of Prl-binding sites reacting with the specific monoclonal antibodies (mAbs), U5 and PrR-7A. Immunoprecipitation of the metabolically labeled CD34+ve cells with the PrR-7A mAb revealed a structure of 43 kD under reducing conditions. Analysis of the early events associated with the Prl/Prl-R interaction showed an increased number of cells engaged in DNA and hemoglobin synthesis. Enhanced erythroid differentiation of CD34+ve cells in the presence of Prl was secondary to upmodulation of receptors for the lineage-specific factor Epo. Together these data demonstrate the existence of a functional interplay between Prl. and hemopoietic factors. © 1995 Wiley-Liss, Inc.     

Chelating derivatives of chitosan obtained by reaction with ascorbic acid

Ascorbic acid immediately dissolves Euphausia superba chitosan upon mixing and forms chitosan ascorbate; during the 6-h period after dissolution in water at pH 5–7, ascorbate is oxidized to dehydroascorbate which undergoes Schiff reaction with the amino groups of chitosan, thus yielding a viscous solution of a polymeric ketimine. The latter is characterized by infrared spectrometry, circular dichroism spectropolarimetry, viscometry and alkalimetry. When brought into contact with transition metal ions, the chitosan ascorbate ketimine yields insoluble metal chelates. Upon reduction with sodium cyanoborohydride, the water-insoluble N-[2-(1,2-dihydroxyethyl)tetrahydrofuryl] chitosan (NDTC) is obtained, which shows enhanced capacity for uranium, up to 800 mg U/g from solutions at pH 4·5.     

Gamma-Decanolactone Alters the Expression of GluN2B,A1 Receptors,and COX-2 and Reduces DNA Damage in the PTZ-Induced Seizure Model After Subchronic Treatment in Mice

Neurochemical Research - Gamma-decanolactone (GD) has been shown to reduce epileptic behavior in different models, inflammatory decreasing, oxidative stress, and genotoxic parameters. This study...     

Linkage Mapping and Molecular Diversity at the Flower Sex Locus in Wild and Cultivated Grapevine Reveal a Prominent SSR Haplotype in Hermaphrodite Plants

Cultivars used for wine and table grape have self-fertile hermaphrodite flowers whereas wild European vines and American and Asian species are dioecious, having either male or female flowers. Consistent with previous studies, the flower sex trait was mapped as a single major locus on chromosome 2 based on a pure Vitis vinifera population segregating for hermaphrodite and female progeny, and a hybrid population producing all three flower sex types. The sex locus was placed between the same SSR and SNP markers on both genetic maps, although abnormal segregation hampered to fine map the genomic region. From a total of 55 possible haplotypes inferred for three SSR markers around the sex locus, in a population of 132 V. sylvestris accessions and 171 V. vinifera cultivars, one of them accounted for 66 % of the hermaphrodite individuals and may be the result of domestication. Specific size variants of the VVIB23 microsatellite sequence within the 3′-UTR of a putative YABBY1 gene were found to be statistically significantly associated with the sex alleles M, H and f; these markers can provide assistance in defining the status of wild grapevine germplasm.     

Fire‐sensitive species dominate seed rain after fire suppression: Implications for plant community diversity and woody encroachment in the Cerrado

Woody encroachment is becoming common in tropical savannas. We studied natural seed rain and performed seed addition experiments in a Brazilian savanna that had not been burned for several decades. We found greater abundance of fire‐sensitive species in the seed rain, likely contributing to woody encroachment. Flexible fire management policies that allow for natural and prescribed fires may be required to maintain savanna diversity.