Showing papers by "University of Extremadura published in 1997"
TL;DR: Data suggest that, in addition to the proposed role for BMP-2 and OP-1 in the establishment of the anteroposterior axis of the limb, they may also play direct roles in limb morphogenesis: (i) in regulating the amount and spatial distribution of the undifferentiated prechondrogenic mesenchyme and (ii) in controlling the location of the joints and the diaphyses of the cartilaginous primordia of the long bones
Abstract: Bone Morphogenetic Protein 2 (BMP-2) and Osteogenic Protein 1 (OP-1, also termed BMP-7) are members of the transforming growth factor beta superfamily. In the present study, we have analyzed the effects of administering them locally at different stages and locations of the chick limb bud using heparin beads as carriers. Our results show that these BMPs are potent apoptotic signals for the undifferentiated limb mesoderm but not for the ectoderm or the differentiating chondrogenic cells. In addition, they promote intense radial growth of the differentiating cartilages and disturb the formation of joints accompanied by alterations in the pattern of Indian hedgehog and ck-erg expression. Interestingly, the effects of these two BMPs on joint formation were found to be different. While the predominant effect of BMP-2 is alteration in joint shape, OP-1 is a potent inhibitory factor for joint formation. In situ hybridizations to check whether this finding was indicative of specific roles for these BMPs in the formation of joints revealed a distinct and complementary pattern of expression of these genes during the formation of the skeleton of the digits. While Op-1 exhibited an intense expression in the perichondrium of the developing cartilages with characteristic interruptions in the zones of joint formation, Bmp-2 expression was a positive marker for the articular interspaces. These data suggest that, in addition to the proposed role for BMP-2 and OP-1 in the establishment of the anteroposterior axis of the limb, they may also play direct roles in limb morphogenesis: (i) in regulating the amount and spatial distribution of the undifferentiated prechondrogenic mesenchyme and (ii) in controlling the location of the joints and the diaphyses of the cartilaginous primordia of the long bones once the chondrogenic aggregates are established.
349 citations
TL;DR: In this article, the role of weight restrictions in Data Envelopment Analysis (DEA) is examined and an alternative approach called contingent weight restriction is proposed, which is both practical and intellectually consistent with the DEA philosophy.
Abstract: This paper examines the role that weight restrictions play in Data Envelopment Analysis (DEA). It is argued that the decision to include a factor (input or output) in a DEA model represents an implicit judgement that the factor has a non-trivial weight. It therefore seems perverse to allow DEA to assign a trivial weight to that factor in assessing the efficiency of a unit. There is therefore a strong case for imposing restrictions on factor weights. However, many existing methods of weight restriction are in practice unwieldy. This paper proposes an alternative approach we term contingent weight restriction which is both practical and intellectually consistent with the DEA philosophy. The paper explores the implications of alternative methods of weight restriction using simulated data from a well known production process.
238 citations
TL;DR: Thirty Iberian × Duroc pigs allotted in groups of ten animals were fed in three traditional different management systems, and Muscle from MO pigs had greater quantities of monounsaturated fatty acids (MUFA) in the total lipids, triglyceride and phospholipid fractions than the other feedings.
186 citations
TL;DR: In this paper, student teachers of primary and secondary science education were compared with their classroom practice when teaching a science lesson and the results indicated that there was no correspondence between the conceptions of the nature of science and the classroom practice.
Abstract: The present article describes research carried out in Badajoz (Spain) with student teachers of Primary and Secondary science education. The preservice teachers‘ conceptions of the nature of science were analyzeda and compared with their classroom practice when teaching a science lesson. The results indicated that there was no correspondence between the conceptions of the nature of science and the classroom practice. The implications of the research for science teacher education are dealt with.
185 citations
TL;DR: In this paper, the dynamics for a system of hard spheres with dissipative collisions is described at the levels of statistical mechanics, kinetic theory, and simulation, where the Liouville operator and associated binary scattering operators are defined as the generators for time evolution in phase space.
Abstract: The dynamics for a system of hard spheres with dissipative collisions is described at the levels of statistical mechanics, kinetic theory, and simulation. The Liouville operator(s) and associated binary scattering operators are defined as the generators for time evolution in phase space. The BBGKY hierarchy for reduced distribution functions is given, and an approximate kinetic equation is obtained that extends the revised Enskog theory to dissipative dynamics. A Monte Carlo simulation method to solve this equation is described, extending the Bird method to the dense, dissipative hard-sphere system. A practical kinetic model for theoretical analysis of this equation also is proposed. As an illustration of these results, the kinetic theory and the Monte Carlo simulations are applied to the homogeneous cooling state of rapid granular flow.
180 citations
TL;DR: In this article, the oxidation of two wastewaters with ozone combined with hydrogen peroxide or UV radiation (254 nm) was compared with those from ozonation alone at similar experimental conditions.
126 citations
TL;DR: In this paper, the solvent response is described by means of point charges chosen in such a way that they reproduce the average value of the solvent electrostatic potential calculated from molecular dynamics data.
Abstract: We present the theory and implementation of a new approach for studying solvent effects. The electronic structure of the solute, calculated at the ab initio level, is obtained in the presence of the surrounding medium. We employ a mean field theory in which the solvent response is described by means of point charges chosen in such a way that they reproduce the average value of the solvent electrostatic potential calculated from molecular dynamics data. In this way, the complete solvent potential can be introduced into the solute Hamiltonian without making use of a one-center multiple expansion of the solute-solvent potential. In the proposed method, only one quantum calculation has to be performed and a great number of configurations can easily be included making the calculation statistically significant. We show that, despite the large fluctuations in the solute charge distribution induced by the solvent, the proposed mean field theory adequately reproduces the energetics and properties of formamide and water molecules in aqueous solution. © 1997 by John Wiley & Sons, Inc.
119 citations
TL;DR: The degradation of olive mill wastewater by aerobic microorganisms has been investigated in a batch reactor, by conducting experiments where the initial concentration of organic matter, quantified by the chemical oxygen demand, and the initial biomass were varied.
Abstract: The degradation of olive mill wastewater by aerobic microorganisms has been investigated in a batch reactor, by conducting experiments where the initial concentration of organic matter, quantified by the chemical oxygen demand, and the initial biomass were varied. The evolution of the chemical oxygen demand, biomass and the total contents of phenolic and aromatic compounds were followed through each experiment. According to the Contois model, a kinetic expression for the substrate utilization rate is derived, and its biokinetic constants are evaluated. This final predicted equation agrees well with all the experimental data.
110 citations
TL;DR: In this paper, a simple and effective procedure to select wine yeasts for industrial use based on technological characteristics of the yeasts was designed, which consists of just two steps: a preselection based on resistance to sulfur dioxide, killer phenotype, growth at high temperature and low foam production and a selection based on volatile acidity, ethanol production, and residual sugars.
107 citations
TL;DR: In this paper, the authors investigated the effect of UV radiation and hydrogen peroxide on tomato wastewaters and found that the contribution of radical reactions in this process was higher than 60%.
104 citations
TL;DR: In this article, a pyrolysis of grape and olive bagasse under different experimental conditions has been studied, where variables were temperature and type and concentration of catalysts, and experiments were carried out in an isothermal manner.
Abstract: Catalyzed pyrolysis of grape and olive bagasse under different experimental conditions has been studied. Variables investigated were temperature and type and concentration of catalysts. Experiments were carried out in an isothermal manner. Products of pyrolysis are gases (H2, CO, CO2, and CH4), liquids (methanol, acetone, furfurylic alcohol, phenol, furfural, naphthalene, and o-cresol), and solids (chars). Temperature is a significant variable, yielding increases of fixed carbon content, gases, and to a lesser extent, ash percentage. Catalyst presence also yields increases of solid phase content, but the amount of liquid components decrease. Among catalysts applied those of Fe and Zn are the most advisable to obtain gases. Chemical treatment of bagasses with sulfuric or phosphoric acid washing leads to lower char yields, although fixed carbon content is higher and ash presence diminishes with respect to catalyst pyrolysis without chemical pretreatment. A pyrolysis kinetic study based on gas generation fro...
TL;DR: A comparatively high hematocrit in males with experimentally enlarged tail ornaments may be a response to increased energetic requirements and, hence, to oxygen demands for flying imposed by their tail morphology.
Abstract: Ornamental tail feathers of male barn swallows (Hirundo rustica) confer an advantage in sexual selection because long-tailed males are preferred by females. However, the size of tail ornaments exceeds the natural selection optimum and males are predicted to pay an energetic cost for flying, directly related to tail length. An increase in hematocrit is an adaptive response to enhance oxygen uptake, for example during periods of intense locomotory activity. In this study, we analyzed the effect of experimental manipulation of tail length on the hematocrit of male barn swallows from an Italian and a Spanish population. We predicted that the natural decrease in hematocrit during the breeding season would be reduced by experimental elongation and enhanced by experimental shortening of tail ornaments. The results showed that the decrease in hematocrit was significantly different among tail treatments, and tail-elongated males had the smallest hematocrit reduction. In Italy, the hematocrit of tail-elongated males did not change after tail manipulation, while that of two control groups and tail-shortened males decreased. A comparatively high hematocrit in males with experimentally enlarged tail ornaments may be a response to increased energetic requirements and, hence, to oxygen demands for flying imposed by their tail morphology.
TL;DR: A brief survey of nonlinear effects in asymmetric reactions can be found in this paper, with a focus on catalysis and autocatalysis applications in the context of catalysis.
Abstract: A brief survey discussing the conceptual considerations of nonlinear effects in asymmetric reactions as well as their recent applications in catalysis and autocatalysis
TL;DR: In this paper, the ac response of ZnO varistors has been investigated over thetemperature range 100 to 380°C using impedance and modulusspectroscopy, and the two components have temperature-dependent activation energies in the ranges,0.52-1.00 and 0.54-0.64 eV, respectively but their resistancesdiffer by 1 to 2 orders of magnitude.
Abstract: The ac response of ZnO varistors has been investigated over thetemperature range 100 to 380°C using impedance and modulusspectroscopy. Impedance spectra show only a single peak, which representsthe most resistive component in the sample and is responsible for the dcproperties, whereas an additional peak appears in the modulus spectrum. Thetwo components have temperature-dependent activation energies in the ranges,0.52–1.00 and 0.54–0.64 eV, respectively but their resistancesdiffer by 1 to 2 orders of magnitude. From their capacitance values, eachrepresents a region ∼100 to 500 A thick; they aretentatively assigned to an electrically-active interface and anintergranular layer.
TL;DR: In this paper, the main characteristics of the charcoals formed and the nature and quantity of gases produced have been determined and a kinetic model of pyrolysis based on gas generation has been accomplished.
Abstract: Pyrolysis of four agricultural residues (maize, sunflower, grape and tobacco) has been carried out in order to quantify their energy content. The main characteristics of the charcoals formed and the nature and quantity of gases produced have been determined. The process was studied batchwise by varying the reaction time (15–60 min) and temperature (400–700°C). Reaction times higher than 30 min do not exert any influence while increasing temperature yields high fixed carbon solids, low volatile content and slight increases in ash. The increase in temperature is specially important to increase the production of gas, mainly hydrogen. From gas composition and proximate analysis, the heating power of gas and solid phases have been determined. A kinetic model of pyrolysis based on gas generation has been accomplished. From this model, rate constants of gas formation at different temperatures and activation energies have also been determined. ©1997 SCI
TL;DR: The aim was to determine the arrangement of the superficial musculature in the area of the triangle of Koch in normal hearts and in hearts with documented AVNRT, to ascertain anatomic features that might contribute to the debate.
Abstract: Atrial Fibers. Introduction: Recent studies suggest that atrial fibers in the approaches to the AV node form part of the dual pathways recognized electrophysiologically in patients with AV nodal reentrant tachycardia (AVNRT). Our aim was to determine, by gross dissection, the arrangement of the superficial musculature in the area of the triangle of Koch In normal hearts and in hearts with documented AVNRT. hoping to ascertain anatomic features that might contribute to the debate.
Methods and Results: We used blunt dissection to study the architecture of the superficial atrial musculature in 16 autopsied hearts from adults who died of noncardiac disease. A well-defined pattern of architecture of muscle fibers was found in the region of the triangle of Koch, showing marked variations in 7 of the 16 specimens. The relationship of these fibers to the histologically specialized AV node was confirmed by histology in three cases. Two hearts from patients with known AVNRT, treated by ablation in one, were examined further histologically. These sections showed that the site of ablation was well distant from the histologically discrete AV node.
Conclusion: The variability in the arrangement of the superficial atrial muscle fibers in the area of the triangle of Koch may be one of the factors influencing the route for impulses entering the AV node. Lesions that ablate nodal reentry are within these atrial fibers rather than the histologically specialized AV node.
TL;DR: Wet air oxidation is presented as a technique for removal of organic pollutants found in waste water streams The oxidation of phenol has been achieved at moderate temperatures (T=473 K) and pressures (30 MPa total pressure) with up to 95% destruction in less than 30 minutes.
TL;DR: In this article, a new current source for low-voltage applications is proposed, which is well suited for biasing differential pairs and source followers and measured compliance voltage is slightly smaller than that of a single transistor.
Abstract: A new current source for low-voltage applications is proposed. This current source is well suited for biasing differential pairs and source followers. Measured compliance voltage is slightly smaller than that of a single transistor. Its output resistance is a factor of 25 larger than that of a single transistor current source and was measured to be 8 M/spl Omega/. The use of the new current source improves the common-mode input range and the common-mode rejection ratio of fully balanced and single-ended differential amplifiers.
TL;DR: Differences in membrane lipid oxidation, between groups followed a similar pattern to that of meat, and Muscle samples from rabbits given the POLY diet were more susceptible to lipid oxidation.
Abstract: The effects of olive (MONO) or sunflower (POLY) oil-enriched (30 g/kg) diets with either a basal (10 mg/kg food) or supplemented (200 mg/kg) level of a-tocopheryl acetate on some measures of production, fatty acid composition of animal tissues and susceptibility to oxidation of rabbit meat and membrane extracts have been studied. MONO diet produced higher levels of C18:1 in animal tissues. Animals that received POLY diet had a higher level of C18:2 in perirenal and neutral fraction of intramuscular fat and higher levels of C18:2, C20:4, C22:4 and C22:5 in phospholipid, reaching a higher overall unsaturation (P = 0·001). Muscle samples from rabbits given the POLY diet were more susceptible to lipid oxidation (P = 0·0001). Differences in membrane lipid oxidation, between groups followed a similar pattern to that of meat. Diets rich in C18:2 resulted in increases in concentration of pentanal (P < 0·001), hexanal (P = 0·0001) and total volatile aldehydes (P = 0·0001) in meat as monitored by headspace gas liquid chromatography. Dietary supplementation with α-tocopheryl acetate reduced the overall concentration of volatile aldehydes (P < 0·05), particularly hexanal (P < 0·05). Dietary administration of monounsaturated fatty acids not only reduces membrane and meat lipid oxidation but also modifies the relative proportion of volatile aldehydes generated upon heating, with a specific decrease in those generally related to rancidity and off-flavour of meats.
TL;DR: It is concluded that corticosterone and prolactin may mediate the increased chemotaxis of peritoneal macrophages induced by exercise.
Abstract: 1. Exercise provokes changes in the immune system, including macrophage activity. Chemotaxis is a necessary function of macrophages if they are to reach the focus of infection and strenuous acute exercise may modulate chemotaxis. However, the precise mechanisms remain unknown. 2. Three experiments were performed in the present study. (1) The effect of strenuous acute exercise (swimming until exhaustion) on the chemotactic capacity of macrophages was evaluated. (2) Peritoneal macrophages from control mice were incubated with plasma from exercised mice or control (no exercise) mice. The differences in the resulting chemotactic capacity were measured. (3) Changes in the concentration of plasma corticosterone and prolactin after exercise were also measured, and the effect of incubation with the post-exercise levels of plasma corticosterone and prolactin on the chemotactic capacity of the peritoneal macrophages was then studied in vitro. 3. Exercise induced an increase in the macrophage chemotaxis index (103 +/- 8 vs. 47 +/- 11 in controls). Incubation with plasma from exercised mice led to an increased level of chemotaxis (68 +/- 18 vs. 40 +/- 6 with plasma from controls). Incubation with concentrations of corticosterone and prolactin similar to those observed in plasma immediately after exercise (corticosterone, 0.72 mumol l-1; prolactin, 88 pmol l-1) raised the chemotactic capacity with respect to that following incubation with the basal concentrations of the hormones in control animals (90 +/- 9 vs. 37 +/- 4 for corticosterone; 72 +/- 9 vs. 41 +/- 4 for prolactin). 4. It is concluded that corticosterone and prolactin may mediate the increased chemotaxis of peritoneal macrophages induced by exercise.
TL;DR: The active constituents in the inhibition of germination are low molecular weight phenolic compounds and the flavonoids appear to exert no direct effect on germination of the species tested, but do provoke a reduction in cotyledon and root size, and could thereby inhibit subsequent seedling development.
Abstract: 1. The allelopathic effect of the exudate secreted by Cistus ladanifer leaves was tested on different plant species. Cynodon dactylon and Rumex crispus, species absent from C. ladanifer scrub (jarales), were clearly inhibited by the exudate.
2. Species present in the jarales, Medicago polymorpha and Lolium rigidum, showed no direct inhibition of germination, but the process this was delayed, and cotyledon and root size was diminished. This implies inhibition of seedling growth, and may explain the low abundance of these species inside the jarales.
3. The active constituents in the inhibition of germination are low molecular weight phenolic compounds. The flavonoids appear to exert no direct effect on germination of the species tested, but do provoke a reduction in cotyledon and root size, and could thereby inhibit subsequent seedling development.
TL;DR: Examination of whether protein kinase C (PKC) activation, calcium mobilization, cytoskeletal organization and small G-protein p21(rho) activation play a role in mediating the stimulation of tyrosine phosphorylation by CCK-8 in acini demonstrates that, in pancreatic acini, CCk-8 causes rapid p125(FAK) and paxillin phosphorylated that is mediated by both phospholipase C-dependent and -
Abstract: Recent studies show that the effects of some oncogenes, integrins, growth factors and neuropeptides are mediated by tyrosine phosphorylation of the cytosolic kinase p125 focal adhesion kinase (p125(FAK)) and the cytoskeletal protein paxillin. Recently we demonstrated that cholecystokinin (CCK) C-terminal octapeptide (CCK-8) causes tyrosine phosphorylation of p125(FAK) and paxillin in rat pancreatic acini. The present study was aimed at examining whether protein kinase C (PKC) activation, calcium mobilization, cytoskeletal organization and small G-protein p21(rho) activation play a role in mediating the stimulation of tyrosine phosphorylation by CCK-8 in acini. CCK-8-stimulated phosphorylation of p125(FAK) and paxillin reached a maximum within 2.5 min. The CCK-8 dose response for causing changes in the cytosolic calcium concentration ([Ca2+]i) was similar to that for p125(FAK) and paxillin phosphorylation, and both were to the left of that for receptor occupation and inositol phosphate production. PMA increased tyrosine phosphorylation of both proteins. The calcium ionophore A23187 caused only 25% of the maximal stimulation caused by CCK-8. GF109203X, a PKC inhibitor, completely inhibited phosphorylation with PMA but had no effect on the response to CCK-8. Depletion of [Ca2+]i by thapsigargin had no effect on CCK-8-stimulated phosphorylation. Pretreatment with both GF109203X and thapsigargin decreased CCK-8-stimulated phosphorylation of both proteins by 50%. Cytochalasin D, but not colchicine, completely inhibited CCK-8- and PMA-induced p125(FAK) and paxillin phosphorylation. Treatment with Clostridium botulinum C3 transferase, which inactivates p21(rho), caused significant inhibition of CCK-8-stimulated p125(FAK) and paxillin phosphorylation. These results demonstrate that, in pancreatic acini, CCK-8 causes rapid p125(FAK) and paxillin phosphorylation that is mediated by both phospholipase C-dependent and -independent mechanisms. For this tyrosine phosphorylation to occur, the integrity of the actin, but not the microtubule, cytoskeleton is essential as well as the activation of p21(rho).
TL;DR: The results are consistent with the handicap principle because long-tailed males experience lower mortality and larger seasonal reproductive success compared with short-tailed male, and the relationships between haematocrit values recorded after migration and the size of ordinary and sexually selected morphological characters in three Barn Swallow populations were analysed.
Abstract: Summary 1. Handicap models of sexual selection propose that male ornaments are indicators of male quality and that honesty is enforced by the costs imposed by the exaggerated ornamental traits. In long-distance migratory birds that feed on the wing, the aerodynamic cost of exaggerated ornamental characters should be particularly high because the size of the ornaments deviates from the natural selection optimum. During migration, birds are expected to raise their oxygen consumption in relation to the energetic demands imposed by their morphology. An increase of haematocrit is an adaptive response to enhance oxygen uptake and efficiency of transfer to the muscular tissues during spells of intense muscular activity. 2. The change of haematocrit of Barn Swallows (Hirundo rustica) after their arrival to the breeding sites, and the relationships between haematocrit values recorded after migration and the size of ordinary and sexually selected morphological characters in three Barn Swallow populations were analysed. 3. Males had higher haematocrit values than females. Individual haematocrit values declined after arrival to the breeding sites. Haematocrit values of males were significantly and positively correlated with the size of their ornamental tail but not correlated with other characters, thus suggesting that well-ornamented males, in order to arrive early, have to raise their haematocrit above the level of short-tailed males. 4. Males and females of similar tail length did not differ in their haematocrit, thus suggesting that sexual dimorphism in haematocrit might be functionally related to dimorphism in tail length. 5. Our results are consistent with the handicap principle because long-tailed males experience lower mortality and larger seasonal reproductive success compared with short-tailed males.
TL;DR: In the combined process, the ozonation pretreatment of OMW achieves a great reduction in the phenolic compounds, leading to a significant increase in the methane yield coefficient in the following anaerobic digestion, its value being 266 ml CH4/g COD.
Abstract: The purification of olive mill wastewaters (OMW) is investigated by a single anaerobic digestion in a batch reactor containing immobilized microorganisms, and by the combination of an ozonation pretreatment followed by an anaerobic digestion. In the single anaerobic digestion the removal of the COD is determined and the methane yield coefficient, which is the best measure of the extent of transformation of the biodegradable substrate, is also obtained, its value being 194 ml CH4/g COD. A kinetic study is performed by using the Monod model combined with the Levenspiel model, due to the presence of inhibition effects. Both models lead to the determination of the kinetic parameters of this anaerobic treatment: kinetic constants, critical substrate concentration of inhibition and inhibitory parameter. In the combined process, the ozonation pretreatment of OMW achieves a great reduction in the phenolic compounds, leading to a significant increase in the methane yield coefficient in the following anaerobic digestion, its value being 266 ml CH4/g COD.
TL;DR: In this article, the degradation of four phenolic acids by single UV radiation and by the advanced oxidation process constituted by the combination of ozone and UV radiation has been conducted, and the quantum yields for each individual reaction are evaluated by means of a competitive kinetic method.
Abstract: The degradation of four phenolic acids by single UV radiation and by the advanced oxidation process constituted by the combination of ozone and UV radiation has been conducted. The phenolic acids, caffeic, p-coumaric, syringic and vanillic, were selected because they are major pollutants which are present in wastewaters from the production of olive oil and from wine distillery plants. In the single photochemical oxidation, the influence of the operating variables is established and the quantum yields for each individual reaction are evaluated by means of a competitive kinetic method. In the combined ozone/UV radiation process, the generation of the hydroxyl radicals improves the degradation rate in comparison to the single oxidations performed: ozonation and UV photodegradation. ©1997 SCI
TL;DR: A cork stopper quality classification system using morphological filtering and contour extraction and following (CEF) as the feature extraction method, and a fuzzy-neural network as a classifier is described, which will be used on a daily basis.
Abstract: Cork is a natural material produced in the Mediterranean countries. Cork stoppers are used to seal wine bottles, Cork stopper quality classification is a practical pattern classification problem. The cork stoppers are grouped into eight classes according to the degree of defects on the cork surface. These defects appear in the form of random-shaped holes, cracks, and others. As a result, the classification cork stopper is not a simple object recognition problem. This is because the pattern features are not specifically defined to a particular shape or size. Thus, a complex classification form is involved, Furthermore, there is a need to build a standard quality control system in order to reduce the classification problems in the cork stopper industry. The solution requires factory automation meeting low time and reduced cost requirements. This paper describes a cork stopper quality classification system using morphological filtering and contour extraction and following (CEF) as the feature extraction method, and a fuzzy-neural network as a classifier. This approach will be used on a daily basis. A new adaptive image thresholding method using iterative and localized scheme is also proposed, A fully functioning prototype of the system has been built and successfully tested. The test results showed a 6.7% rejection ratio, It is compared with the 40% counterpart provided by traditional systems. The human experts in the cork stopper industry rated this proposed classification approach as excellent.
TL;DR: The results of this study confirm that individual housing of female rats provoke variations in certain biochemical parameters, and that if this is not taken into account in performing different scientific studies, it could give rise to unreliable or even dubious results.
Abstract: Individual housing has been reported to modify animal behaviour. The present study compares the plasma levels of glucose, triglycerides and total cholesterol, weight, and food and water intake in two groups of female rats. Group A: 10 rats who remained grouped in two cages for 21 days; and Group B: 10 rats housed in two cages for 7 days, then isolated in individual cages from day 8 to day 15, and finally grouped together again for the last 7 days of the study.The results showed that the plasma values of glucose declined (P<0.05) in the Group B rats when they had been returned to group condition (4.79±0.72 mM) than when they had been isolated (5.45±0.94 mM). Plasma triglyceride levels were lower (P<0.05) in isolated rats (0.70±0.26 mM) than in any determination of the grouped rats. Group B: 1st week 1.21±0.21 mM, 3rd week 0.88±0.20 mM; and Group A: 1.22±0.20, 0.96±0.16, and 0.96±0.36 mM, in the first, second, and third week, respectively. There were no statistically significant differences in total cholest...
TL;DR: Male-male interactions may have played a role in the evolution of plumage brightness, either in the context of competition for mates or for resources when males gather into unisexual groups.
TL;DR: The method proposed was used, with good results, for the determination of the three compounds in milk, and a potential of -600 mV was selected as the working potential.
TL;DR: This PCR detection protocol provides a sensitive and relatively rapid technique for the routine detection of Clostridium botulinum in foods.
Abstract: A PCR procedure was developed for the detection of Clostridium botulinum in foods. PCR products were detected in agarose gels and by Southern hybridization. The sensitivity of PCR was tested in broth cultures and in canned asparagus, dry cured ham and honey. The sensitivity of the method in broth was high (2.1-8.1 cfu ml-1) for types A and B, but rather low (10(4) cfu ml-1) for types E and F. However, after enrichment at 37 degrees C for 18 h, it was possible to detect Cl. botulinum types A, B, E and F in food samples at initial levels of about 1 cfu 10 g-1 of food. This PCR detection protocol provides a sensitive and relatively rapid technique for the routine detection of Cl. botulinum in foods.