Showing papers by "University of Extremadura published in 1996"

Role of TGF beta s and BMPs as signals controlling the position of the digits and the areas of interdigital cell death in the developing chick limb autopod

Abstract: The establishment of the digital rays and the interdigital spaces in the developing limb autopod is accompanied by the occurrence of corresponding domains of expression of TGF beta s and BMPs. This study analyzes whether these coincident events are functionally correlated. The experiments consisted of local administration of TGF beta-1, TGF beta-2 or BMP-4 by means of heparin or Affi-gel blue beads to the chick limb autopod in the stages preceding the onset of interdigital cell death. When beads bearing either TGF beta-1 or -2 were implanted in the interdigits, the mesodermal cells were diverted from the death program forming ectopic cartilages or extra digits in a dose- and stage-dependent fashion. This change in the interdigital phenotype was preceded by a precocious ectopic expression of ck-erg gene around the bead accompanied by down-regulation of bmp-4, msx-1 and msx-2 gene expression. When BMP-beads were implanted in the interdigital spaces, programmed cell death and the freeing of the digits were both accelerated. Implantation of beads bearing BMP-4 at the tip of the growing digits was followed by digit bifurcation, accompanied by the formation of an ectopic area of cell death resembling an extra interdigit, both morphologically and molecularly. The death-inducing effect of the BMP beads and the chondrogenic-inducing effect of the TGF beta beads were antagonized by the implantation of an additional bead preabsorbed with FGF-2, which constitutes a signal characteristic of the progress zone. It is concluded that the spatial distribution of digital rays and interdigital spaces might be controlled by a patterned distribution of TGF beta s and BMPs in the mesoderm subjacent to the progress zone.

Pyrolysis of two agricultural residues: Olive and grape bagasse. Influence of particle size and temperature

Abstract: The pyrolysis of olive and grape bagasse has been studied with the aim of determining the main characteristics of the charcoals formed and the nature and quantity of gases and liquids produced. Variables investigated were temperature between 300 and 900°C and particle size between 0.4 and 2 mm diameter. Experiments were carried out in an isothermal manner. As a general rule, particle size does not exert any influence, whereas temperature is a very significant variable. Thus an increase in this variable yields an increase in the fixed carbon content, gases produced and, to a lesser extent, ash percentage. On the other hand, volatile material and solid yields decrease with increasing temperature. The principal gases generated are H2, CH4, CO and CO2, while among the liquid components the presence of methanol, acetone, furfuryl alcohol, phenol, furfural, naphthalene and o-cresol has to be highlighted. Heating values of both gas and solid phases were determined from gas composition and elemental carbon analysis. The quality of charcoals and heating value allow the conclusion that the most convenient temperature for the pyrolysis should be between 600 and 700°C, at which the production of liquids is at its maximum. Finally, a kinetic study of the pyrolysis, based on gas generation from thermal decomposition of residues, has been carried out. From this model, rate constants for the formation of each gas and their corresponding activation energies were determined.

Pollen production in anemophilous trees

Abstract: A study was made of the total pollen production per individual tree in ten anemophilous arboreal species (including wild, cultivated and ornamental species) of considerable aerobiological importance: Pinus pinaster, Ulmus minor, Juglans regia, Platanus hispanica, Quercus rotundifolia, Salix atrocinerea, Populus nigra, Acer negundo, Olea europaea and Fraxinus angustifolia. For each species three isolated well-shaped specimens of medium height were chosen, and the number of flowers per individual tree and the number of pollen grains per anther was estimated. The values of total pollen production varied between a little over 1000 million grains in Juglans regia and more than 500,000 million in one single tree in Quercus rotundifolia. For the production of pollen grains per anther, the values oscillated between 3000 grains in Juglans regia and 100,000 in Olea europaea. There is an exponential correlation between the size of the anthers and the number of pollen grains they contain. A linear correlatio...

Ventricular myoarchitecture in tetralogy of Fallot.

Abstract: BACKGROUND: Little attention has been paid to the architecture of the muscle fibres of the ventricular walls in congenitally malformed hearts. In this study the gross pattern of myocardial fibres in normal hearts was compared with that in cases of tetralogy of Fallot. METHODS AND RESULTS: After morphological examination nine specimens with tetralogy were dissected to study the ventricular myoarchitecture. Changes were found in the shape of the malformed ventricles. The ventricular walls were arranged in layers in all hearts. Superficial and deep layers were present in both ventricles, with the superficial layer showing a more oblique orientation in the specimens with tetralogy than in normal hearts. Modifications of muscle fibre that were related to the type of malformation were seen in the deep layer. A middle layer was present in the left ventricles of normal hearts and specimens with tetralogy: this showed a horizontal orientation in both groups. In contrast, a middle layer was found in the right ventricle only in specimens showing tetralogy. CONCLUSIONS: The malformed hearts showed modifications in ventricular shape, in the arrangement of muscle in the right ventricle, and in the overall myoarchitecture. These changes could well be the consequence of the same agent (or agents) that caused the structural defect.

Concepciones y prácticas de aula de profesores de ciencias, en formación inicial de primaria y secundaria

Abstract: The present article describes a research carried out with four student teachers of primary and secondary science education. The preservice teachers’ conceptions of the nature of science and learning and teaching of science were analyzed and compared with their classroom practice when teaching science lessons. Transfer of the conceptions to the classroom was not immediate and there was influence from other factors. Lastly the implications of the research for teacher education are discussed.

Data envelopment analysis applied to quality in primary health care

Abstract: The performance of primary care should ultimately be judged on its effect on the health outcome of individual patients. However, for the foreseeable future, it is inconceivable that the outcome data necessary to come to a judgement on performance will be available. And in any case, specification of the statistical model necessary to analyze outcome is fraught with difficulty. This paper therefore sets out a model of primary care performance which is based on the premise that certain measurable quality indicators can act as proxies for outcome. This being the case, a model of performance can be deduced which takes into account the effect of resources and patient characteristics on outcome. The most appropriate analytic technique to make this model operational is data envelopment analysis (DEA). It is argued that DEA can handle multiple dimensions of performance more comfortably, and is less vulnerable to the misspecification bias that afflicts statistically based models. The issues are illustrated with an example from English Family Health Service Authorities.

Disposition of fluvoxamine in humans is determined by the polymorphic CYP2D6 and also by the CYP1A2 activity.

Abstract: Background Fluvoxamine is a selective serotonin reuptake inhibitor used widely in the treatment of depression and other psychiatric diseases, but little is known about the specific isozymes involved in its metabolism. This study investigated the relationship between fluvoxamine disposition and the polymorphic CYP2D6 and the polycyclic aromatic hydrocarbon (as contained in cigarette smoke) inducible CYP1A2. Methods Fluvoxamine (50 mg orally) was given to 10 extensive metabolizers and four poor metabolizers of debrisoquin, and concentrations were assessed in plasma by high performance liquid chromatography. Five of the extensive metabolizers and one of the poor metabolizers were smokers of more than 10 cigarettes per day. The CYP1A2 activity was determined by means of a urinary caffeine test. Results Compared with nonsmoking extensive metabolizers, nonsmoking poor metabolizers had a statistically significant (p = 0.02, Mann-Whitney Utest) about twofold higher maximum plasma concentration, longer half-life, and fivefold lower oral clearance of fluvoxamine. The oral clearance of fluvoxamine correlated to the CYP1A2 index in the 14 subjects (rs = 0.58; p < 0.05; Spearman rank correlation). Conclusion The disposition of fluvoxamine in humans is associated with the polymorphic CYP2D6 activity, but CYP1A2 also seems to be involved. Clinical Pharmacology & Therapeutics (1996) 60, 183–190; doi:

Determination of Lennard-Jones interaction parameters using a new procedure

Abstract: For theoretical and chemical engineering applications, accurate and, if possible, simple models of molecular interactions are needed. We have recently proposed a new procedure for determining Lennard-Jones interaction parameters for fluids, forcing agreement between the values of the pressure obtained from empirical equations of state and those obtained from computer simulations. In this work we obtain new intermolecular Lennard-Jones parameters for non-polar molecules, taking into account their deviation from the spherical shape by means of an acentric factor. Our procedure could help to connect the microscopic and macroscopic worlds and it will be progressively implemented in order to obtain a better representation of other substances and mixtures of chemical interest.

Oxidation of Polynuclear Aromatic Hydrocarbons in Water. 3. UV Radiation Combined with Hydrogen Peroxide

Abstract: Oxidation in water of three polynuclear aromatic hydrocarbons (PAHs), fluorene, phenanthrene, and acenaphthene, with UV radiation combined with hydrogen peroxide has been studied. The effect of hydrogen peroxide concentration, pH, and bicarbonate ion has been investigated. Disappearance rates of PAHs are substantially increased with respect to those from UV radiation alone if proper conditions of hydrogen peroxide concentration and pH are established. Direct photolysis contribution decreases with the increasing hydrogen peroxide concentration and is the main way of degradation at acid pH (76% at pH 2 with 10-3 M hydrogen peroxide concentration, for fluorene oxidation). Rate constants of reactions between the hydroxyl radical and PAHs were found to be 9.9 × 109, 8.8 × 109, and 13.4 × 109 M-1 s-1, for fluorene, acenaphthene, and phenanthrene, respectively. Both UV radiation and UV/H2O2 oxidation of PAHs yield numerous intermediate compounds. Most of these compounds disappear as oxidation time is increased.

Interethnic differences in drug metabolism: influence of genetic and environmental factors on debrisoquine hydroxylation phenotype.

Abstract: Genetic and environmental factors are determinants of the interindividual and interethnic variability in drug metabolism. The metabolism of several important drugs (e.g. haloperidol) cosegregates with that of debrisoquine. Thus, interethnic differences in debrisoquine hydroxylation polymorphism (CYP2D6) might be partly responsible for the variation in haloperidol disposition between races. The influence of tobacco, ethanol, caffeine, gender, and oral contraceptive use on the debrisoquine metabolic ratio (MR) has been analyzed in 633 Spanish healthy volunteers. MR was also determined in panels of healthy volunteers. 18 smokers were studied during a tobacco abstinence period, and 31 women three times during the same menstrual cycle. Among EMs, debrisoquine MR was significantly (P < 0.05) lower during smoking cessation (mean antilog +/- SD, 0.48 +/- 0.29) compared to a smoking period (0.61 +/- 0.23). During the lutheal phase of the menstrual cycle, debrisoquine MR was also significantly (P < 0.01) lower (0.33 +/- 0.41) compared to the ovulatory-phase (0.41 +/- 0.34) and the phase before ovulation (0.44 +/- 0.36). Among EMs, it is suggested that debrisoquine MR may be modified by tobacco smoking and sexual hormones. The clinical relevance of these findings remains unclear.

Measuring sensorial quality of Iberian Ham by Rasch model

Abstract: This paper focuses on a fresh way to determine quality of ham according to sensorial analysis. It is an application of latent traits theory to biometry. “Quality of Iberian Ham” can be considered a latent variable defined by a set of sensorial analysis factors (items). The theoretical background is Item Response Theory (IRT), which suggests that if we can understand how each item in a set of items operates with an object, then we can estimate a measure for the object. The Rasch model is the most common model for that theory. This technique has been applied to data from 8 different hams assessed by 15 expert judges tasting ham in order to obtain Rasch measurements for hams and calibrations for the items.

Environmental and human influence on the ecology of Trichinella spiralis and Trichinella britovi in Western Europe.

Abstract: Surveys on Trichinella parasites in domestic and sylvatic animals collected in France, Italy, and in the Extremadura region of Spain showed that the distribution of Trichinella spiralis and Trichinella britovi is influenced by both environmental and human behaviour factors. In France, both Trichinella species are prevalent in the fox population from mountain areas and natural parks but are infrequent in wild boars (< 0.001%). In Italy, only T. britovi is present in sylvatic animals (foxes, wolves, and mustelids) living 500 m above sea level. This species is rare in wild boars (< 0.001%) in that area. Sylvatic trichinellosis is found in only 24% and 34% of French and Italian territory, respectively, while lowland areas may generally be considered Trichinella-free, because the domestic cycle is absent. The ecology of T. spiralis and T. britovi in the Extremadura shows a different picture from that observed in France and Italy because of the presence of both domestic and sylvatic cycles. The domestic cycle not only allows the maintenance of T. spiralis in the domestic environment, but it also has a great impact on the prevalence in wild boar populations. It does not influence the prevalence in vulpine populations. These data suggest (1) that domestic trichinellosis occurs only in rural areas of Western Europe in association with traditional swine-rearing practices, but not in industrialized pig farms; (2) that sylvatic trichinellosis occurs only in natural habitats which, in Western Europe, are widespread in mountain areas; (3) that the fox is the primary reservoir in the sylvatic cycle, where the parasite is maintained in a closed circuit and (4) that among sylvatic animals T. spiralis is present at lower altitude than is T. britovi.

Sexual selection for male body mass and the evolution of litter size in mammals

Abstract: Interspecific variation in litter size is one of the most puzzling features of mammalian life-history diversity. In polygynous mammals, sexual selection by male-male competition often favors increased body size. Because adult body size, and hence reproductive success, are commonly related to maternal expenditure, I hypothesize that sexual selection for male body size can favor female reproductive strategies of single-birth parental allocation. To test this hypothesis, I made comparisons of sexual dimorphism in body size and litter size variations, after controlling for the effect of body mass, for 106 species of mammals. The results show that increases in sexual dimorphism are accompanied by decreases in the number of offspring per litter. Body mass is related to reductions in litter size only for larger mammals, whereas sexual dimorphism is negatively correlated with litter size throughout the whole range of species of all included taxa. Thus, the results support the hypothesis that sexual selection for ...

Monte Carlo simulation method for the Enskog equation.

Abstract: A Monte Carlo simulation method to numerically solve the Enskog equation for a hard-sphere fluid is proposed. The method is based on and extends Bird's direct simulation Monte Carlo method to solve the Boltzmann equation. The main modifications are (a) the two particles of a collision pair are taken from cells separated a distance equal to the diameter of the spheres; (b) the collision rate is enhanced by a factor that accounts for the spatial correlations. The method is applied to uniform shear flow and proved to be consistent with (i) the exact pressure tensor obtained from the Enskog equation at local equilibrium for large shear rates, (ii) the viscous heating equation, and (iii) the Navier-Stokes shear viscosity obtained from the Enskog equation. \textcopyright{} 1996 The American Physical Society.

Identification and prevalence study of 17 allelic variants of the human NAT2 gene in a white population.

Abstract: The prevalence and distribution of seven point mutations at the coding region of the highly polymorphic NAT2 gene were studied in 1008 chromosomes from healthy Spanish subjects. Most of the genes studied (78.4%) had one or more mutations, distributed in seventeen allelic variants of the NAT2 gene. Three alleles were present at high frequencies, namely NAT2*5B (41.6%), NAT2*6A (23.6%) and NAT2*4 (21.6%). The frequencies for the rest of alleles were: NAT2*12A (2.5%), NAT2*6B (2.0%), NAT2*13 (1.9%), NAT2*5A (1.5%), NAT2*7B (1.2%), NAT2*12C (1.0%), NAT2*5C (0.8%), NAT2*14C (0.8%), NAT2*14A (0.6%), NAT2*5D (0.3%), NAT2*12B (0.2%), and NAT2*14D (0.1%). In addition, we identified two new allelic variants with mutations at 191A + 341C + 803G (0.1%) and 282T + 590A + 803G (0.3%) which to our knowledge are described here for the first time. No other combination of mutations was identified, including the previously described allelic variants NAT2*14B, NAT2*14E, NAT2*5E and NAT2*7A. The phenotype predictive capacity of simplified PCR tests including analyses for mutations at 341C and 590A, and more sophisticated tests analysing seven mutations revealed that, in the population studied, the analysis of these two mutations is enough to predict as rapid acetylators over 99.5% subjects with two rapid genes, and about 94% subjects with one rapid gene. Given a prevalence of poor acetylators of about 55% subjects, the simplified analysis would predict the phenotype in about 97.5% subjects.

Presence of antibodies in the aqueous humour and cerebrospinal fluid during Leishmania infections in dogs. Pathological features at the central nervous system

Abstract: In the present paper we show that in dogs, naturally infected with Leishmania infantum, the aqueous humour and the cerebrospinal fluid contain anti-Leishmania IgGs and that the specificity of antigen recognition of these fluids is similar to that of the sera. We also show that in the encephalon and cerebellum of these dogs there is a pathological sponge-like reaction accompanied by neuronal degeneration, mobilization of glial cells together with accumulation of amyloid deposits. The interstitial and intravascular deposition of IgGs and Leishmania antigens in choroid plexus suggest that in these animals there is a failure of the blood-cerebrospinal and ciliary bodies filtration barriers which may allow the transfer of anti-Leishmania IgGs from the blood stream to these fluids. We suggest that the failure of the blood-cerebrospinal barrier and the in situ concentration of anti-Leishmania IgGs and antigens in brain tissues may predispose to the pathological features detected in this compartment.

In vivo inhibition of programmed cell death by local administration of FGF-2 and FGF-4 in the interdigital areas of the embryonic chick leg bud.

Abstract: The formation of the digits in amniote vertebrates is accompanied by a massive degeneration process that accounts for the disappearance of the interdigital mesenchyme. The establishment of these areas of interdigital cell death (INZs) is concomitant with the flattening of the apical ectodermal ridge (AER), but a possible causal relationship between these processes has not been demonstrated. Recent studies have shown that the function of the AER can be substituted for by implantation of beads bearing either FGF-2 or FGF-4 into the apical mesoderm of the early limb bud. According to these observations, if the onset of INZs is triggered by the cessation of the AER function, local administration of FGFs to the interdigital tissue prior to cell death should delay or inhibit interdigit degeneration. In the present study we have confirmed this prediction. Implanting Affi-gel blue or heparin beads pre-absorbed with either FGF-2 or FGF-4 into the interdigital tissue of the chick leg bud in the stages prior to cell death stimulates cell proliferation and causes the formation of webbed digits. Vital staining with neutral red confirmed an intense temporal inhibition of interdigital cell death after FGF treatment. This inhibition of interdigital cell death was not accompanied by modifications in the pattern of expression of Msx-1 or Msx-2 genes, which in normal development display a domain of expression in the interdigital tissue preceding the onset of degeneration.

Antigenic cross-reactivity in mice between third-stage larvae of Anisakis simplex and other nematodes

Abstract: We used ELISA and immunoblotting to investigate antigenic cross-reactivity in mice between third-stage larvae of Anisakis simplex and five other nematodes: the ascaridoids Ascaris suum, Toxocara canis and Hysterothylacium aduncum, and the nonascaridoids Trichinella spiralis and Trichuris muris. Two sera were raised against each species (including A. simplex, but excluding A. suum), by infection or by immunization with somatic antigens. Serum against A. suum was raised by immunization only. The reactivities of each serum with A. simplex somatic antigens (SA), excretion-secretion antigens (ES), pseudocoelomic fluid antigens (PF) and cuticular antigens (CA) were investigated. The results of ELISA indicated high antigenic cross-reactivity between A. simplex and the remaining ascaridoid nematodes, confirming that there is extensive antigenic similarity within this group of nematode parasites. Immunoblotting again confirmed the high degree of cross-reactivity between the SA of A. simplex and SAs of the other ascaridoids, although several A. simplex SA components in the 11-18 kDA range were only recognized by sera from mice infected with A. simplex. In addition, two A. simplex PF components of 22 and 27 kDA, were recognized only by sera from mice infected with, or immunized with the SA of, A. simplex. Finally, the anti-phosphorylcholine monoclonal antibody BH8 recognized only a small number of A. simplex antigens, indicating that phosphorylcholine epitopes are not significant contributors to the observed cross-reactivity with the other nematodes.

Gram-positive, catalase-positive cocci from dry cured Iberian ham and their enterotoxigenic potential

Abstract: Iberian ham is an uncooked, cured meat product ripened under natural uncontrolled conditions for 18 to 24 months. Gram-positive, catalase-positive cocci are the main microbial population in Iberian ham for most of the ripening time. Since some of these organisms are able to produce enterotoxins, adequate characterization and toxicological study are needed. For this, 1,327 gram-positive, catalase-positive cocci, isolated from Iberian hams at different stages and locations, were characterized by physiological and biochemical tests. Selected isolates were further characterized by guanine-cytosine (G+C) content and restriction enzyme analysis of genes coding for 16S rRNA. The toxigenic potential of these organisms was tested with specific DNA gene probes for staphylococcal enterotoxins A, B, C, and D and confirmed by semiquantitative sandwich enzyme immunoassay. The majority of the isolates were identified as Staphylococcus spp. and Micrococcus spp. Non-identified gram-positive, catalase-positive cocci which were moderately halophilic and showed a 42 to 52% G+C content were detected. A great variety of staphylococcal strains were found within the different species at any sampling time. Two strains of Staphylococcus xylosus, one Staphylococcus cohnii strain, and four of the non-identified organisms with 42 to 52% G+C contents hybridized with some of the DNA probes for C and D staphylococcal enterotoxin genes. S. xylosus hybridizing with C-enterotoxin probe reacted with both C and D enterotoxins in the immunological test. In addition, enterotoxin D was confirmed in the nonidentified strains. Some toxigenic organisms were isolated from the final product, posing a health hazard for the consumer.

Recalibration of Two Earlier Potential Energy Surfaces for the CH4 + H → CH3 + H2 Reaction. Application of Variational Transition-State Theory and Analysis of the Kinetic Isotope Effects Using Rectilinear and Curvilinear Coordinates

Abstract: We present a recalibration of the two most recent analytical potential energy surfaces for the CH4 + H → CH3 + H2 reaction. Assuming a correct functional form, the recalibration process allows one to update the original parameters in light of new experimental and theoretical data. As calibration criteria we use the reactant and product experimental properties, and the most recent ab initio saddle-point properties, which differ from the original values, especially the imaginary frequency. For both modified surfaces we use rectilinear and curvilinear coordinates to calculate the vibrational frequencies at nonstationary points. The rate coefficients are calculated with variational transition-state theory and, in general, agree with the experimental data in the temperature range 300−1500 K. They present only a slight dependence on the modified surfaces used but a major dependence on the choice of coordinate system, especially at low temperatures where the rectilinear coordinates yield rate coefficients practi...

Increased risk for hepatocellular carcinoma in NAT2-slow acetylators and CYP2D6-rapid metabolizers

Abstract: The arylamine N-acetyltransferase (NAT2) is a polymorphic enzyme which is expressed in the liver in a genotype-determined manner. NAT2 is involved in activation and inactivation of carcinogens through N-acetylation. We studied the role of this polymorphism in the development of hepatocellular carcinoma (HCC). One hundred consecutive patients diagnosed for HCC and 258 healthy volunteers were studied for NAT2 genotype. The occurrence of seven enzyme-inactivating and silent point mutations in the coding region of the NAT2 gene was studied by mutation-specific PCR amplification. An excess of subjects homozygous for NAT2 loss of function alleles was observed among patients with HCC (68% vs 53.9% controls). The relationship between the slow acetylator NAT2 genotype and HCC risk is more pronounced in patients lacking serum HBV and HCV markers. The additional determination of alleles of the cytochrome P450 2D6 (CYP2D6) gene in the same subjects confirmed our previous findings that subjects with two active CYP2D6 genes are at increased risk of developing HCC. The genetic polymorphism of NAT2 is a relevant factor in the risk for developing HCC (inverse odds ratio slow vs rapid = 1.8; 95% CI 1.1-3.0). The inverse odds ratio for subjects with two risk genotypes (two defect NAT2 genes and two or more active CYP2D6 genes) is 2.6 (95% CI 1.6-4.4) for all patients with HCC, and 5.6 (95% CI 1.4-33.3) for patients without serum viral markers.

Perspectives on the mitochondrial multiple conductance channel.

Abstract: A multiple conductance channel (MCC) with a peak conductance of over 1 nS is recorded from mitoplasts (mitochondria with the inner membrane exposed) using patch-clamp techniques. MCC shares many general characteristics with other intracellular megachannels, many of which are weakly selective, voltage-dependent, and calcium sensitive. A role in protein import is suggested by the transient blockade of MCC by peptides responsible for targeting mitochondrial precursor proteins. MCC is compared with the peptide-sensitive channel of the outer membrane because of similarities in targeting peptide blockade. The pharmacology and regulation of MCC by physiological effectors are reviewed and compared with the properties of the pore hypothesized to be responsible for the mitochondrial inner membrane permeability transition.

A study on the glycaemic balance in streptozotocin-diabetic rats treated with an aqueous extract of Ficus carica (fig tree) leaves

Abstract: The hypoglycaemic effect of an aqueous extract of Ficus carica leaves was studied in streptozotocin-diabetic rats The extract induced a significant hypoglycaemic effect after either oral- or intraperitoneal (ip) administration Body weight loss was prevented in treated diabetic rats and the survival index was significantly affected by plasma insulin levels Results show that Ficus carica aqueous extract has a clear hypoglycaemic activity in treated versus non-treated diabetic rats The mechanism involved in such an effect is not elucidated

Detection of leishmania infantum amastigotes in canine choroid plexus

Abstract: not be easily detected in coloured hair. Due to the restricted numbers of suitable animals, this initial trial was run in two parts. In the first part four animals were treated with ivermectin/clorsulon and four animals acted as controls. In the second part, four animals were treated with doramectin and again four animals were used as controls. Animals treated with ivermectin/clorsulon in this initial trial became infested when challenged on days 21 and 28, while the doramectin treated animals remained louse-free. In the trial reported here, more animals were available, both to be infested and for use as donors, to increase the numbers and period of time that L vituli was available for challenge. Louse-free Friesian or Ayrshire calves were housed in groups of four prior to and during the experimental period. As before, the trial was carried out in two equal parts (Table 1). In each part, one group of four animals was treated with ivermectin/clorsulon (Ivomec Super Injection; MSD Agvet) and another group of four animals with doramectin (Dectomax; Pfizer), both drugs being given at the manufacturer's recommended dose rate. A further group of four animals remained as untreated controls which were infested on day zero and then observed for louse infestation twice a week throughout the trial period. Two ivermectin/clorsulon and two doramectin treated calves were infested individually with 50 L vituli on day 14 after drug injection and were observed for louse attachment four and seven days later. On day 21, two more ivermectin/clorsulon and a further two doramectin treated calves were infested individually with 50 L vituli lice and observed for louse attachment four and seven days later. Provided the animals remained clear of lice they were reinfested 14 days after the first challenge thus calves used on day 14 were reused on day 28 and those used on day 21 were reused on day 35. In part 1, one calf from day 21 was showing seasonal hair loss making it unsuitable for rechallenge and so a louse-free animal from day 28 was rechallenged as a substitute for it on day 35. All untreated control calves became infested with lice, demonstrating the reliability of the infestation technique. Results obtained from the treated animals showed that all of the calves treated with either ivermectin/clorsulon or doramectin remained louse-free after challenge on day 14. In each part of the trial, one of the animals treated with ivermectin/clorsulon and challenged on day 21 became infested. In the case of the doramectin treatment, all animals challenged on days 21 and 28 remained lousefree. In the first part of the trial both doramectin-treated animals remained louse-free after challenge on day 35 but at this point in the second part one of them became positive for louse establishment (Table 2). The present results thus confirm that ivermectin/clorsulon will give persistent protection against L vituli for more than 14 days but less than 21, while doramectin will give more than 28 days protection but less than 35. Endectocides have given farmers the opportunity to control ectoparasites at the same time as worming their cattle. In the case of lice the main advantage is seen to be a curative rather than a preventive one, and farmers sometimes complain, usually after a time interval of some months, that louse infestations have returned. Some of these could be the results of reinfestation following mixing of treated and untreated animals in common housing, and in this case the longer the preventive action of the endectocide the less the likelihood of complaints.

Morphology and significance of programmed cell death in the developing limb bud of the vertebrate embryo

Abstract: Cell death constitutes a basic mechanism accounting for many morphogenetic and histogenetic events during normal and abnormal development of embryonic organs and tissues. This article focuses on the major areas of mesodermal cell death occurring during vertebrate limb development. In early stages of limb development, cell death appears to reduce the amount of mesodermal tissue destined to form the anlage of the autopodium. In later stages, cell death plays a role sculpturing the shape of the digits. The morphology of the dying cells corresponds with apoptosis, but internucleosomal DNA fragmentation by endonuclease activation does not appear to be a precocious feature. The cell death program can be inhibited in vivo and in vitro by changing the environmental conditions of the prospective dying cells up to 6-10 h before death. In this review, we survey possible factors controlling the establishment of the cell death program. Information concerning the biochemical basis of cell death in the developing limb is also revised. Finally, the possible role of genes whose pattern of expression is coincident with the dying processes is discussed.

Changes in plasma enzyme activities in professional racing cyclists.

Abstract: OBJECTIVE: To reports changes in plasma levels in professional racing cyclists. METHODS: Plasma levels of the intracellular enzymes aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transpeptidase, lactate dehydrogenase, and alkaline phosphatase were measured resting and after exercise in professional cyclists participating in two road races: Vuelta Ciclista a Valencia (800 km, beginning of the cyclist season), and the top rank race Vuelta a Espana (2700 km, at the end of cyclist season). RESULTS: A significant increase in plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase was observed at the end of the race over the corresponding paired start values (P < 0.05). The increase in plasma lactate dehydrogenase after the race was only statistically significant (P < 0.05) in the Vuelta a Espana. The longer the duration of the cycle tour race, the greater were the increases in aspartate aminotransferase and alanine aminotransferase levels. The high levels returned to their start values during the overnight resting period. CONCLUSIONS: The presence of these enzymes in the blood is probably due to mechanically damaged muscle cells leaking their contents into the interstitial fluid.