Search results for "HAp"
showing 10 items of 2767 documents
17β-Estradiol-dependent regulation of chaperone expression and telomerase activity in the marine sponge Geodia cydonium
1999
It is known that species belonging to the lowest metazoan phylum, the Porifera (sponges), do not develop tumors. Sponge cells share with tumor cells of higher animals at least one characteristic; they contain high levels of telomerase activity, suggesting that they possess a high proliferation capacity. This assumption, however, has not been substantiated experimentally. In addition, sponges show a specific bauplan, leading us to postulate that they undergo apoptosis to replace a given set of cells at a given time. In the present study, 17β-estradiol (βE2) was used as a defined agent to assess its effect on both the telomerase activity and the process of apoptosis in the marine sponge Geodi…
Fluorescence excitation and emission spectroscopy on single MEH-PPV chains at low temperature.
2008
Fluorescence emission and excitation spectra of single MEH-PPV polymer molecules dispersed in thin PMMA films have been recorded at 1.2 and 20 K. We observe single as well as multichromophore emission in single chain emission spectra, whereby the relative fractions depend on the two different molecular weights (50 and 350 kDa) studied. The molecular weight also affects the distribution of peak emission maxima, which is monomodal (bimodal) for the low (high) molecular weight. The appearance of an additional "red" subpopulation for the high molecular weight sample is attributed to interactions of multiple chromophores from a sufficiently flexible single chain. The comparison of emission spect…
Distinct amino acids of the Oenococcus oeni small heat shock protein Lo18 are essential for damaged protein protection and membrane stabilization
2010
The small heat shock protein (smHsp) Lo18 from lactic acid bacteria Oenococcus oeni reduces in vitro thermal aggregation of proteins and modulates the membrane fluidity of native liposomes. An absence of information relating to the way in which the smHsp demonstrates a stabilizing effect for both proteins and membranes prompted this study. We expressed three Lo18 proteins with amino acid substitutions in Escherichia coli to investigate their ability to prevent E. coli protein aggregation and their capacity to stabilize E. coli whole-cell membranes. Our results showed that the alanine 123 to serine substitution induces a decrease in chaperone activity in denaturated proteins, and that the ty…
Evidence for the plant-specific intercellular transport of the Arabidopsis copper chaperone CCH
2001
Summary Arabidopsis copper chaperone (CCH) belongs to a family of eukaryotic proteins that participates in intracellular copper homeostasis by delivering this metal to the secretory pathway. In this work we show that the CCH protein is mainly located along the vascular bundles of senescing leaves and petioles, as shown by tissue prints and immunohistochemical detection. CCH protein also accumulates in stem sieve elements and is collected in phloem exudates. Accordingly, Arabidopsis CCH is the only member of the metallochaperone family described to function intercellularly to date. Moreover, the CCH protein remains stable when plants are subjected to excess copper that causes a rapid and spe…
Enzymatic Resolution of 3-oxodicyclopentadiene on a Decagram Scale
2018
The chiral building block 3-oxodicyclopentadiene (1) can be readily resolved on a decagram scale by a short sequence consisting of (1) reduction to the corresponding endo-alcohol, (2) enzymatic oxidative resolution with a ketoreductase enzyme to give (+)-1 and the (+)-form of the endo-alcohol, and (3) reoxidation of the (+)-endo-alcohol with another ketoreductase to give (–)-1. With a selectivity factor of 310, the enantiomeric ratios of the resolved (+)-endo-alcohol and (+)-ketone are both >99:1. Both enzymatic oxidations could be performed with a at least 300:1 substrate/catalyst ratio (w/w).
Regulatory Changes in Pterin and Carotenoid Genes Underlie Balanced Color Polymorphisms in the Wall Lizard
2018
ABSTRACTReptiles use pterin and carotenoid pigments to produce yellow, orange, and red colors. These conspicuous colors serve a diversity of signaling functions, but their molecular basis remains unresolved. Here, we show that the genomes of sympatric color morphs of the European common wall lizard, which differ in orange and yellow pigmentation and in their ecology and behavior, are virtually undifferentiated. Genetic differences are restricted to two small regulatory regions, near genes associated with pterin (SPR) and carotenoid metabolism (BCO2), demonstrating that a core gene in the housekeeping pathway of pterin biosynthesis has been co-opted for bright coloration in reptiles and indi…
An Insight into Substrate-Dependent Fluorination of some Highly Substituted Alicyclic Scaffolds
2017
The substrate-dependent fluorination of some highly-functionalized cyclopentane derivatives with multiple chiral centers has been investigated. The key steps of the stereocontrolled syntheses are the oxidative cleavage of the ring carbon–carbon double bond of readily available diexo or diendo norbornene β-amino acid derivatives followed by transformation of the resulted dialdehyde stereoisomers by reduction. Finally, substrate-directable chemodifferentiation of different types of hydroxy groups under fluorination procedures gave various densely functionalized alicyclic derivatives or heterocycles.
Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters – diastereomeric control o…
2020
Twenty clusters of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters. A catalytic mechanism involving an active Ru3 catalyst generated by CO loss from [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] has been investigated by DFT calculations. peerReviewed
Associations of age, body size, and maturation with physical activity intensity in different laboratory tasks in children
2021
We investigated the associations of age, sex, body size, body composition, and maturity with measures of physical activity (PA) intensity in children. PA intensity was assessed using VO2 as % of VO2reserve or VO2 at ventilatory threshold (VT), muscle activity measured by textile electromyography, mean amplitude deviation (MAD) measured by accelerometry, and metabolic equivalent of task (MET) during laboratory activities.Age, stature, and muscle mass were inversely associated with VO2 as % of VO2reserve and % of VT, during walking or running on a treadmill for 4, 6, and 8 km/h (Spearman r = -0.645 to -0.358). Age was inversely associated with MAD during walking on treadmill for 4 km/h (r = -…
Impacto de la alorreactividad NK en el trasplante haploidéntico de progenitores hematopoyéticos asociado al uso de ciclofosfamida postrasplante
2022
Introducción: El trasplante haploidéntico de progenitores hematopoyéticos (haplo-TPH) es una opción terapéutica, cuando no se dispone de donante HLA-idéntico. Sin embargo, existe controversia sobre qué factores son los que tienen implicación pronóstica en la selección del donante. Objetivos: Identificar factores relevantes para escoger el mejor donante haploidéntico. Para ello se analizaron aspectos clínicos e inmunológicos. Dentro de los distintos modelos de predicción de la alorreactividad NK, este estudio pretende conocer cuál aporta mayor información. Material y método: Estudio prospectivo multicéntrico de 113 parejas donante-receptor (D/R). Los pacientes, con diversas patologías, tras …