Showing papers by "University of Extremadura published in 1987"
TL;DR: The fiber architecture of the ventricular myocardium has been studied in elasmobranchs and teleost fish species with hearts displaying mixed types of ventricular musculature (compact and trabecular) and the possible relationship between myocardial fiber architecture and ventricular shape is discussed.
Abstract: The fiber architecture of the ventricular myocardium has been studied in elasmobranch (Isurus oxyrhinchus, Galeorhinus galeus, Prionace glauca) and teleost (Xiphias gladius, Thunnus thynnus, Thunnus alalunga) fish species with hearts displaying mixed types of ventricular musculature (compact and trabecular). In all cases, the compact myocardium is organized in layers of fiber bundles with an orderly arrangement within the ventricular walls. The number of these layers appears to be dependent on the relative thickness of the compact myocardium. Differences in the pattern of myocardial fiber arrangement were observed among the different fish species. In elasmobranchs the compact myocardium at the level of the atrioventricular orifice is continuous with the trabeculated myocardium. Furthermore, in elasmobranchs the trabeculated myocardium displays a precise arrangement in arcuate trabeculae running from the auriculoventricular to the conoventricular orifices. In teleosts, the compact myocardium is independent of the trabeculated myocardium and a large number of fibers insert into the bulboventricular fibrous ring. The trabeculated myocardium in these species displays an anarchic arrangement except at the level of the bulboventricular orifice, where the fibers tend to be aligned longitudinally, also being inserted into the fibrous ring. Minor differences, consisting mainly of the presence of extra bundles of fibers, were also observed among different individuals of the same species. The possible relationship between myocardial fiber architecture and ventricular shape is discussed.
57 citations
TL;DR: In this article, the authors used sawdust, cubes (20 × 20 × 20 mm) and octagonal prisms (20× 20 × 80 mm) by heating in nitrogen under dynamic (sawdust and cubes) and isothermal (sawdust and prisms) conditions to different final temperatures.
50 citations
TL;DR: The results show that ridge removal causes condensation and rounding of the underlaying mesenchymal cells followed by chondrogensis after surgical removal of AER of the interdigital spaces of the chick leg bud at stage 28–30.
Abstract: In the present work we have studied the mechanism of formation and the possible morphogenetic significance of the process of ectopic chondrogenesis induced by surgical removal of AER of the interdigital spaces of the chick leg bud at stage 28–30 (Hurle and Ganan 1986). Our results show that ridge removal causes condensation and rounding of the underlaying mesenchymal cells followed by chondrogensis. The long-term study of the fate of these ectopic cartilages shows that in a high percentage of the cases the cartilages undergo morphogenesis taking by day 10 of incubation the appearance of the two distal phalanges of an extra-digit. These extra-digits lack tendons and are joined by thin interdigital membranes to the neighboring digits.
44 citations
TL;DR: In this article, the authors developed approximate bounded solutions of the equation x " +bx'+c 1 x'+ c 1 x +c 3 x 3 = 0 with b > 0, c 1 ≷0 and c 3 ≷ 0.
27 citations
01 Jun 1987
TL;DR: In this article, a numerical method which allows one to evaluate vibrational properties of solutes is presented, which derives from a combination of quantum-mechanical methods describing vibrations in vacuo and solvent effects in the continuum approximation.
Abstract: A numerical method which allows one to evaluate vibrational properties of solutes is presented The method derives from a combination of quantum-mechanical methods describing vibrations in vacuo and solvent effects in the continuum approximation The performances of the simplest case in a sequence of models that can be dealt with by this method are examined using HF and (HF) 2 as molecular probes in three different physical situations(in vacuo and in two solvents of different polarity) The results agree with the available knowledge on monomers and dimers in solution
25 citations
TL;DR: The effects produced in vitro by Cefmetazol, Cefoxitin and Imipenem on the chemotaxis, spontaneous mobility, adherence, phagocytosis and candidicide power of human polymorphonuclear neutrophils (PMNs) are investigated.
Abstract: 1. We have investigated the effects produced in vitro by Cefmetazol, Cefoxitin and Imipenem on the chemotaxis, spontaneous mobility, adherence, phagocytosis and candidicide power of human polymorphonuclear neutrophils (PMNs). 2. The three antibiotics tested significantly stimulated the adherence of neurtrophils to nylon fibre at doses either equal (50 mg/l) or superior (500 mg/l) to the therapeutic one. 3. Cefmetazol, Cefoxitin and Imipenem bring about a maximum increase of chemotaxis at the therapeutic dose, whereas the spontaneous mobility diminishes with any one of the doses used. 4. The capacity of the PMNs to phagocytize and produce lysis of Candida albicans is increased in Cefmetazol with therapeutic doses. Cefoxitin produced an increased lysis of candidas .
24 citations
TL;DR: Lipoxygenase was partially purified (26-fold) from tomato fruits by ammonium sulphate precipitation and hydrophobic chromatography, and further characterized by disc gel electrophoresis, chromatofocusing and M , determination.
23 citations
TL;DR: The kinetic analysis of the time dependence of the light-scattering data after the osmotic shock shows that, in the absence of local anesthetics, the Mg2+ influx can be described as proceeding through a unique type of channel, however, Ca2+, influx appears to involve two channel of different kinetic properties.
21 citations
TL;DR: The events that occur during the early development of the optic chiasm of the chick embryo have been studied by light and scanning electron microscope and primitive glial cells first appear in the ventrorostral region of the early chiasm in stage 26, increasing in number from this stage on.
Abstract: The events that occur during the early development of the optic chiasm of the chick embryo have been studied by light and scanning electron microscopy. In developmental stages previous to the arrival of the first optic fibres in the floor of the diencephalon, as well as during the arrival of the leading fibres, extracellular spaces can be seen in the diencephalon ventral wall. These spaces are defined by external cell prolongations which end in a foot-shaped formation. During stages 25 and 26 a prechiasmic degenerative centre appears in the area immediately rostral to the early chiasm, leading to a notable degree of disorganization in the diencephalon wall. This centre appears to be related to the reorganization of the system of external cell processes and extracellular spaces which become progressively more irregularly distributed, coinciding with the arrival of the first optic fibre fascicles to the midline of the floor of the diencephalon. The optic fibre fascicles change their latero-medial directionality in the medial-most regions of the ventral diencephalon, where their course becomes rostrocaudal. This reorientation of the optic fibres seems to be mediated by primitive glial cells which first appear in the ventrorostral region of the early chiasm (previously occupied by the system of external cell processes and extracellular spaces) in stage 26, increasing in number from this stage on. The morphology of the primitive glial cells is laminar in nature and the cells are seen to be densely packed together with no large extracellular spaces between them.
20 citations
TL;DR: The susceptibility of Listeria monocytogenes to hydrogen peroxide in sterilized and raw milk was studied and it was found that the microorganism was less susceptible to H2O2 than milk microflora.
19 citations
TL;DR: The main components of the mineral matter of a Spanish coal (ASTM classification as high volatile A bituminous) were shown, by X-ray diffraction studies and ash analyses, to be quartz, kaolin and mica.
TL;DR: In this article, a study of the catalytic effect of some compounds of the alkali and alkaline-earth metals on the gasification reactions in CO 2 and in steam of chars from a semi-anthracite with a high inorganic matter content was made.
TL;DR: In this paper, the position of acetylation on the imidazolidine-2-thione ring was demonstrated by spectroscopic data and by transformation of CSaC-O groups.
TL;DR: A kinetic method is described for determining trace amounts of manganese(II), based on its catalytic effect on the oxidation of salicylaldehyde guanylhydrazone by hydrogen peroxide, by measuring the rate of change of absorbance at 505 nm.
TL;DR: In this article, the Jacobian elliptic functions are applied to the motion of monzero-rest-mass particles in the Schwarzschild geometry, and the bound and unbound trajectories are analyzed together with their classical and special-relativity limits.
Abstract: The Jacobian elliptic functions are applied to the motion of monzero-rest-mass particles in the Schwarzschild geometry. The bound and unbound trajectories are analysed together with their classical and special-relativity limits.
TL;DR: In this paper, a molecular dynamics simulation is used to establish the dependence of the Helmholtz free energy on temperature and density, and the influence of the attractive forces on the structure of dense fluids.
TL;DR: It is suggested that the gel-to-liquid crystalline phase transition of the lipid is able to shift the conformational equilibrium E ⇌ E∗ of Ca2+, Mg2+-ATPase.
TL;DR: Cytosol 5'-nucleotidase (EC 3.3.1.5) has been purified near homogeneity from Artemia embryos, and the enzyme cleaves preferentially IMP and GMP, and to a lesser extent other 5'-mononucleotides.
Abstract: Cytosol 5'-nucleotidase (EC 3.1.3.5) has been purified near homogeneity from Artemia embryos. The enzyme cleaves preferentially IMP and GMP, and to a lesser extent other 5'-mononucleotides. The substrate-velocity plot was hyperbolic with GMP and sigmoidal with AMP. The hydrolysis of GMP is stimulated both by ATP and beta, gamma-methyleneadenosine 5'-triphosphate with the same activation constant of around 0.6 mM. Both nucleotides decreased S0.5 without affecting V. The molecular mass of the native purified enzyme was 165 kDa, and one major band of 42 kDa was detected after sodium dodecyl sulphate polyacrylamide gel electrophoresis.
TL;DR: Observations of glioblast morphology in different developmental stages suggest that these cells undergo radial migration toward peripheral regions of the stalk, which is discussed in relation to possible mechanisms through which optic fiber fascicles, initially located on the surface of the stalking stalk, come to lie in deeper areas ofThe stalk wall.
Abstract: Light and electron microscopy was used to study the chick embryo optic stalk from Hamburger and Hamilton stages 21 to 29. Observations of glioblast morphology in different developmental stages suggest that these cells undergo radial migration toward peripheral regions of the stalk. Immediately previous to and during migration, morphological changes were noted in the glioblasts, including the appearance of lateral prolongations which contribute to the subdivision of optic fiber fascicles and the radial elongation of their nucleus, which gives the impression of squeezing itself into the peripheral glioblastic prolongation. These phenomena occur in a retino-diencephalic direction, commencing in the distal optic stalk during stage 23 and continuing in subsequent stages. The significance of glioblastic migration is discussed in relation to possible mechanisms through which optic fiber fascicles, initially located on the surface of the stalk, come to lie in deeper areas of the stalk wall.
TL;DR: It is observed that the AER flattens out in the zone of cleft formation while in the digital portions of the autopodium it takes on a polystratified appearance.
Abstract: This report documents the development of the autopodium of the common chameleon (Chamaeleo chamaeleo) using light microscopy, scanning electron microscopy, and transmission electron microscopy. Three main periods were distinguished during the morphogenesis of this structure. In the first period (stages 33-35 of chameleon development) the autopodium is paddle-shaped with a prominent apical ectodermal ridge (AER) along the distal margin. During this period the AER has structural features similar to other reptilian and avian vertebrates except for the scarcity or absence of gap junctions. The second period of autopodium morphogenesis (stage 36 of chameleon development) is characterized by the formation of a central cleft which divides this structure into two digital segments. In the forelimb the autopodial cleft occupies the space between digits 3 and 4. In the hindlimb the cleft occupies the space between digits 2 and 3. Mesenchymal cell death constitutes a constant feature during cleft formation. In addition to cell death during this process, we have observed that the AER flattens out in the zone of cleft formation while in the digital portions of the autopodium it takes on a polystratified appearance. In the last period of autopodial morphogenesis (stage 37 of chameleon development) digits become free by means of interdigital mesenchymal cell death.
TL;DR: In the course of measurements of uranium contamination in rivers of the Guadiana basin, this paper found the logical contamination near the uranium mines and a234U/238U ratio near 1 in the neighbourhood of the sources.
Abstract: In the course of measurements of uranium contamination in rivers of the Guadiana basin we have found the logical contamination near the uranium mines and a234U/238U ratio near 1 in the neighbourhood of the sources. With distance we find not only the expected decreasing contamination but also higher values of the activity ratio234U/238U. This observation seems to contradict the usual explanation of preferential leaching of234U as origin of the general234U enrichment of ground water.
TL;DR: The results indicate that the vasodepressor effects induced by PB are essentially due to an interference of the barbiturate with the Ca2+ entry into the vascular smooth muscle cell in both kinds of arteries and with the intracellular Ca3+ movements in femoral ones.
TL;DR: The results suggest that the primary B action on the OPP pathway is at the first enzyme (glucose‐6P‐dehydrogenase) level and that the B effect on 6P‐gluconate‐deHydrogenase is secondary to this.
Abstract: Both enzymatic activities increased under B‐deficient and B‐toxic treatments. The ortho‐diphenolic content did not change with B levels. Our results suggest that the primary B action on the OPP pathway is at the first enzyme (glucose‐6P‐dehydrogenase) level and that the B effect on 6P‐gluconate‐dehydrogenase is secondary to this. The B action on the enzymatic activities seems not to be caused by any direct interaction with substrates, as B infiltration of B‐deficient culture “in vivo”; seems to result in long term effects on cell structures and/or processes not easily r In this paper the glucose‐6P‐dehydrogenase and 6P‐gluconate ‐ dehydrogenase activities and ortho‐diphenolic content of hydroponically‐cultivated sunflower‐leaves with moderately deficient, normal and toxic B levels were measured. The change in these parameters during time was considered, together with the restoration of enzymatic activities by means of borate infiltration of deficient and normal leaves. The micronutrient content o...
TL;DR: In this paper, a spectrofluorimetric method is described for the determination of trace amounts of beryllium, based on its reaction with Nuclear Fast Red, which can be used to determine between 10 and 80 ng ml-1 of BER.
Abstract: A spectrofluorimetric method is described for the determination of trace amounts of beryllium, based on its reaction with Nuclear Fast Red. The detection limit is 3 ng ml–1 and the method can be used to determine between 10 and 80 ng ml–1 of beryllium. The stoicheiometry of the complex is 1 : 1. The method has been satisfactorily applied to the determination of beryllium in rocks, alloys and steels.
TL;DR: In this article, the structure and coordination positions of pyrimidinic ligands have been proposed based on spectroscopic studies (IR, 1H-NMR and UV-visible) and magnetic measurements.
Abstract: Seven Hg(II), Pd(II), Cu(II), and Ag(I) complexes of two 7-oxo-vic-triazolo[4,5-d]pyrimidine derivatives have been obtained. The complexes were characterized by spectroscopic studies (IR,1H-NMR and UV-visible) and magnetic measurements. On the basis of these data both the structure of the complexes and the coordination positions of the pyrimidinic ligands have been proposed. Likewise, the thermal behaviour of the complexes has also been studied.
TL;DR: In this article, a violet complex with Fe(II) in strongly acid medium was used for the Spectrophotometric determination of Fe (II) (determination limit 0.20 μg · ml −1 in homogeneous medium and 0.022 μg · cm −1 by extraction with isoamyl alcohol).
TL;DR: In this paper, the 1H and 13C NMR chemical shifts and H-H couplings for five peracetylated 1-deoxy-1-nitroheptitols are reported.
Abstract: The 1H and 13C NMR chemical shifts and H-H couplings for five peracetylated 1-deoxy-1-nitroheptitols are reported. From these spectra the preponderant conformation at room temperature of each compound has been determined, and compared with other alditols with the same configuration.
TL;DR: In this paper, a new method for the spectrofluorometric determination of lanthanum traces is proposed (λex = 465 nm, λem = 580 nm), for concentrations between 0.1 and 1.0 μg ml−1.