Esterase activity and isoenzymes in relation to morphogenesis in Mammillaria gracillis Pfeiff. tissue culture

Cactus Mammillaria gracillis Pfeiff. (Cactaceae), cultivated in vitro, spontaneously switches from an organised to unorganised way of growth, producing a habituated organogenic callus which regenerates normal and hyperhydric shoots without the addition of any growth regulators. Tumour tissues, induced by A. tumefaciens wild strain B6S3 (tumour TW) and rooty mutant GV3101 (tumour TR), do not express any organogenic potential. The esterase (arylesterase EC 3.1.1.2 and carboxylesterase EC 3.1.1.1) activity and isoenzyme pattern of morphologically different cactus tissues: shoot, callus, hyperhydric regenerant, tumours TW and TR, were compared. Tissue samples were frozen at –80 °C and lyophilized before protein extraction. Two esterase substrates, 1- and 2-naphthylacetate, were used. Esterase activity of all tissues varied during the period of one subculture. In shoots and tumours, the highest esterase activity for both substrates was measured on the 21st day, while in the callus and hyperhydric regenerants the highest activity was on the 7th day. Esterases were separated electrophoretically in polyacrylamide gradient gels under non-denaturating conditions. In total, 13 isoesterases, reacting with both substrates, were resolved. No differences in isoenzyme profile were noticed in correlation with the age of tissues, but the esterase activity varied among tissues. The significance of these results is discussed

Esterase activity and isoenzymes in relation to morphogenesis in Mammillaria gracillis Pfeiff. tissue culture

Cactus Mammillaria gracillis Pfeiff. (Cactaceae), cultivated in vitro, spontaneously switches from an organised to unorganised way of growth, producing a habituated organogenic callus which regenerates normal and hyperhydric shoots without the addition of any growth regulators. Tumour tissues, induced by A. tumefaciens wild strain B6S3 (tumour TW) and rooty mutant GV3101 (tumour TR), do not express any organogenic potential. The esterase (arylesterase EC 3.1.1.2 and carboxylesterase EC 3.1.1.1) activity and isoenzyme pattern of morphologically different cactus tissues: shoot, callus, hyperhydric regenerant, tumours TW and TR, were compared. Tissue samples were frozen at –80 °C and lyophilized before protein extraction. Two esterase substrates, 1- and 2-naphthylacetate, were used. Esterase activity of all tissues varied during the period of one subculture. In shoots and tumours, the highest esterase activity for both substrates was measured on the 21st day, while in the callus and hyperhydric regenerants the highest activity was on the 7th day. Esterases were separated electrophoretically in polyacrylamide gradient gels under non-denaturating conditions. In total, 13 isoesterases, reacting with both substrates, were resolved. No differences in isoenzyme profile were noticed in correlation with the age of tissues, but the esterase activity varied among tissues. The significance of these results is discussed

From Bio-waste to Bone Substitute: Synthesis of Biomimetic Hydroxyapatite and Its Use in Chitosan-based Composite Scaffold Preparation

Nanocomposite structure of the bone can be mimicked by chitosan/hydroxyapatite (CS/HAp) composite scaffold. Biological hydroxyapatite (HAp) contains various ions, which have a crucial role in bone growth. The aim of the present work was to synthesize biomimetic hydroxyapatite and prepare composite scaffolds based on chitosan, where HAp was synthesised from hen eggshells, seashells and cuttlefish bone. The powders were composed of nano-structured calcium deficient HAp and amorphous calcium phosphate (ACP). In the as-prepared powders, Sr2+, Mg2+ and Na+ ions were detected as a result of using biogenic precursor of Ca2+ ions. Highly porous CS/HAp structures have been prepared by freeze-gelation technique. The CS/HAp scaffolds have shown highly porous structure with very well interconnected pores and homogeneously dispersed HAp particles. The MTT assay of CS/HAp scaffolds has shown no toxicity, and the live/dead assay has confirmed good viability and proliferation of seeded cells. This work is licensed under a Creative Commons Attribution 4.0 International License

Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy

The magnetization processes in binary magnetic/nonmagnetic amorphous alloy Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied with the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained with the superparamagnetic behaviour of the single domain magnetic clusters inside the nonmagnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found out that magnetic clusters occupy the characteristic volume from 25 up to 200 nm3 . The validity of the superparamagnetic model of Hf_{57}Fe_{43} is based on the concentration of iron in the Hf_{100-x}Fe_{43} system that is just below the threshold for the long range magnetic ordering. This work throws more light on magnetic behaviour of other amorphous alloys, too

8Li+alpha decay of 12B and its possible astrophysical implications

The 12B excitation energy spectrum has been obtained from coincidence measurements of the 9Be+7Li -> 2alpha+8Li reaction at E{0}=52 MeV. The decay of the states at excitations between 10 and 16 Mev into alpha$+8Li has been observed for the first time. Observed alpha-decay indicates possible cluster structure of the 12B excited states. The influence of these states on the cross section of the astrophysically important 8Li(alpha,n)11B and 9Be+t reactions is discussed and the results are compared with existing results.Comment: accepted for publication in Europhysics Letter

Composition and Morphology Investigation of NiCoB Nanoparticles, as-Prepared and Coated by SiO2

NiCoB nanoparticles, as-prepared and coated by SiO2, were synthesized by chemical reduction of metallic salts. The as-prepared samples were additionally annealed at 650 for 1 hour in argon atmos-phere. All samples (the as-prepared and annealed ones) were investigated by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). According to FE-SEM observations each of the investigated samples was composed of nearly spherical nanoparticles with average dimension smaller than 30 nm. Also, tendency of formation of irregular agglomerates was present in both cases of the as-prepared and annealed investigated samples. XRD measurements of as-prepared samples revealed fully amorphous structure. In case of annealed samples, crystallization of different phases was confirmed (as a consequence of heat treatment at 650 C). The existence of these phases was also observed from FE-SEM micrographs as different morphologies present in the samples.(doi: 10.5562/cca2234

Acute poisoning due to trichloroethylene ingestion

Opisan je slučaj akutnog otrovanja trikloretilenorn putem ingestije. Bolesnica je zabunom popila 50 ml trikloretilena umjesto rakije. Glavni simptom otrovanja bila je narkoza. Povodom ovog slučaja autori raspravljaju 31 slučaj otrovanja ingestijom iz stručne literature.A case of acute trichloroethylene poisoning due to accidental ingestion of approximately 50 ml of the toxic agent is presented. General anaesthaesia was the outstanding feature in the clinical course of the intoxication. The authors review the cases from the literature adding their case to the 31 already reported. Discussing the laboratory findings in the presented case the authors express their opinion that the metabolism of thrichloroethylene when ingested does not essentially differ from the metabolism of the same substance when inhaled

17.2 Cardiac resynchronization: Multicenter experience with a new coronary sinus lead

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