Biomedical subjects

Abel Moreno

Publications and source records attributed to Abel Moreno.

8 recordsLinked to original sources

PubMed2006

Colloidal aggregation phenomena: Spatial structuring of TEOS-derived silica aerogels.

In this contribution, the homogeneity of silica aerogels made from tetraethyl orthosilicate (TEOS) was studied by means of Fourier transform infrared (FTIR) and 29Si nuclear magnetic resonance (NMR) spectroscopies. FTIR spectra show a slight difference in the asymmetric Si-O-Si stretching vibration frequency in the outer and inner part of the aerogels. According to the 29Si NMR data, a higher relation Q4/Q3 was obtained in the inner parts of the gels compared with their outer parts, proving the difference in the cross linkage of the silica network. The obtained results are interpreted in terms of the specific spatial structuring of the colloidal suspensions due to the presence of gravity.

Journal Article↗

PubMed2006

Enzymatic polymerization of phenolic compounds using laccase and tyrosinase from Ustilago maydis.

Flavonoids are a big group of polyphenols of low molecular weight with in vitro antioxidant properties. In this study, the laccase and tyrosinase from Ustilago maydis were partially characterized and their effect on the antioxidant activity of some phenolic compounds was investigated. Since enzymatic polymerization of the phenolic compounds was detected, the size of the aggregates was determined and related to their antioxidant activity. Morphology of the polymers was analyzed by atomic force microscopy. The results showed that the laccase- and tyrosinase-catalyzed polymerization of quercetin produced aggregates with relatively low molecular weight and higher antioxidant activity than the monomeric quercetin. In the case of kaempferol, the aggregates reached higher sizes in the first 2 h of reaction and their antioxidant activity was increased. In the last case, the aggregates adopted fractal-ordered shapes similar to coral in the case of the kaempferol-laccase system and to fern in the case of the kaempferol-tyrosinase system. The kaempferol and quercetin polymers at low concentration had strong scavenging effect on Reactive oxygen species (ROS) and inhibition of lipoperoxidation in human hepatic cell line WRL-68.

Antioxidants↗

PubMed2005

Conceptions and first results on the electrocrystallization behaviour of ferritin.

The role of electrochemical processes on Fe and CdSO(4) in the crystallization of horse spleen ferritin has been investigated using the cyclic voltammetry technique. It was found that although both species exhibit important redox properties in the presence of an external applied potential, CdSO(4) played a leading role not only in the nucleation process but also in the growth behaviour and morphology of ferritin crystals.

Animals↗

PubMed2005

Heavy metal stress reduces the deposition of calcium oxalate crystals in leaves of Phaseolus vulgaris.

Calcium oxalate (CaOx) crystals in plants may serve as a sink for the absorption of excess calcium, and they could play an important role in heavy metal detoxification. In this study, the effect of heavy metals and different calcium concentrations on the growth of calcium oxalate crystals in leaves of Phaseolus vulgaris was investigated. Different analytical techniques were used to determine the influence of exogenous lead and zinc on CaOx deposition and to detect a presence of these metals in CaOx crystals. We found a positive correlation between the calcium concentration in the nutrient medium and the production of calcium oxalate crystals in leaves of hydroponically grown plants. On the other hand, addition of the heavy metals to the nutrient medium decreased the number of crystals. Energy dispersive X-ray spectrometry did not detect the inclusion of heavy metals inside the CaOx crystals. Our investigation suggests that CaOx crystals do not play a major role in heavy metal detoxification in P. vulgaris but do play an important role in bulk calcium regulation.

Calcium Oxalate↗

PubMed2004

Crystal structure of ovocleidin-17, a major protein of the calcified Gallus gallus eggshell: implications in the calcite mineral growth pattern.

Ovocleidin-17 (OC17) from Gallus gallus is one of the best candidates to control and regulate the deposition of calcium carbonate in the calcified eggshell layer. Here, the crystal structure of monomeric OC17, determined at a resolution of 1.5 A, was refined to a crystallographic R-factor of 20.1%. This is the first protein directly involved in a non-pathological biomineralization process resolved by x-ray diffraction to date. The protein has a mixed alpha/beta structure containing a single C-type lectin-like domain. However, although OC17 shares the conserved scaffold of the C-type lectins, it does not bind carbohydrates. Nevertheless, in vitro OC17 modifies the crystalline habit of calcium carbonate (CaCO3) and the pattern of crystal growth at intervals of 5-200 microg/ml. Determining the three-dimensional structure of OC17 contributes to a better understanding of the biological behavior of structurally related biomolecules and of the mechanisms involved in eggshell and other mineralization processes.

Amino Acid Sequence↗

PubMed2003

Crystallochemical characterization of calcium oxalate crystals isolated from seed coats of Phaseolus vulgaris and leaves of Vitis vinifera.

Calcium oxalate crystals are a major biomineralization product in higher plants. Their biological function and use are not well understood. In this work, we focus on the isolation and crystallochemical characterization of calcium oxalate crystals from seed coats of Phaseolus vulgaris (prisms) and leaves of Vitis vinifera (raphides and druses) using ultrastructural methods. A proposal based on crystal growth theory was used for explaining the existence of different morphologies shown by these crystals grown inside specialized cells in plants.

Calcium Oxalate↗

PubMed2002

Separating nucleation and growth in protein crystallization using dynamic light scattering.

A means of controlling crystallization is to separate the phases of nucleation and growth. Methods to achieve this, other than seeding, involve lowering the supersaturation by changing the temperature or diluting drops after incubating them for a given time at nucleation conditions. However, by the time nuclei or crystals are visible under the microscope too many nuclei will have formed. Dynamic Light Scattering was applied practically, to determine the most likely time for nucleation-growth decoupling to be performed successfully. The time at which DLS showed a significant change in the size-distribution of species in solution, corresponded to that optimal time.

Animals↗

PubMed2002

Crystallization and preliminary x-ray analysis of ovocleidin-17 a major protein of the gallus gallus eggshell calcified layer.

In this work, we report the crystallization of ovocleidin-17, the major protein of the avian eggshell calcified layer and the preliminary X-ray characterization of this soluble protein which is implied into the CaCO(3) formation of the eggshell in avians. Crystals belong to one of the trigonal space group P3 with cell dimensions a= b= 59.53 A and c = 83.33 A, and alpha=beta= 90 degrees and gamma=120 degrees. Crystals diffract up to 3.0 A.

Animals↗