oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2018 ( 8 )

2017 ( 5 )

2016 ( 12 )

2015 ( 98 )

Custom range...

Search Results: 1 - 10 of 4063 matches for " PA Contreras "
All listed articles are free for downloading (OA Articles)
Page 1 /4063
Display every page Item
Plasma retinol concentration in grazing heifers: First data obtained from a dairy herd in the south of Chile
Chihuailaf,RH; González,CS; Wittwer,F; Contreras,PA;
Archivos de medicina veterinaria , 2008, DOI: 10.4067/S0301-732X2008000100009
Abstract: there is no information available about plasma retinol concentration in grazing heifers in chile, for this reason the plasma retinol concentration was measured in dairy heifers grazing during the winter and spring seasons on paddocks in the south of chile. fifteen clinically healthy friesian heifers from a dairy farm located in the valdivia province, chile, aged between 16 and 18 months, were used. the animals were grazing on fertilized natural pastures from july to december. blood samples were taken monthly from each animal and plasma retinol concentrations were determined using reverse-phase high performance liquid chromatography. mean (± sd) plasma retinol concentration was 0.46 ± 0.09 μg/ml with values fluctuating between 0.18 - 0.69 μg/ml. plasma retinol concentration was lower in winter (0.42 ± 0.09 μg/ml, with values fluctuating between 0.18 to 0.57 hg/ml) and higher in spring (0.50 ± 0.09 μg/ml; with values fluctuating between 0.29 to 0.69 μg/ml). the average values obtained in this study constitute the first data currently available in chile regarding plasma retinol concentration in grazing cattle
Plasma retinol concentration in grazing heifers: First data obtained from a dairy herd in the south of Chile Concentraciones plasmáticas de retinol en vaquillas a pastoreo: Primeros valores obtenidos en un reba o del sur de Chile
RH Chihuailaf,CS González,F Wittwer,PA Contreras
Archivos de medicina veterinaria , 2008,
Abstract: There is no information available about plasma retinol concentration in grazing heifers in Chile, for this reason the plasma retinol concentration was measured in dairy heifers grazing during the winter and spring seasons on paddocks in the south of Chile. Fifteen clinically healthy Friesian heifers from a dairy farm located in the Valdivia Province, Chile, aged between 16 and 18 months, were used. The animals were grazing on fertilized natural pastures from July to December. Blood samples were taken monthly from each animal and plasma retinol concentrations were determined using reverse-phase high performance liquid chromatography. Mean (± SD) plasma retinol concentration was 0.46 ± 0.09 μg/ml with values fluctuating between 0.18 - 0.69 μg/ml. Plasma retinol concentration was lower in winter (0.42 ± 0.09 μg/ml, with values fluctuating between 0.18 to 0.57 Hg/ml) and higher in spring (0.50 ± 0.09 μg/ml; with values fluctuating between 0.29 to 0.69 μg/ml). The average values obtained in this study constitute the first data currently available in Chile regarding plasma retinol concentration in grazing cattle En Chile no existen antecedentes sobre la concentración de retinol en plasma sanguíneo de bovinos a pastoreo, por ello el objetivo de este estudio fue medir las concentraciones plasmáticas de retinol en vaquillas a pastoreo en invierno y primavera y comparar ambos períodos. Para el estudio se utilizaron 15 vaquillas Frisón negro, clínicamente sanas, entre 16 y 18 meses de edad, mantenidas a pastoreo sobre praderas naturales mejoradas. Mensualmente de cada animal se obtuvo muestras de sangre, desde julio hasta diciembre. Las concentraciones plasmáticas de retinol se midieron utilizando cromatografía líquida de alto rendimiento en fase reversa. Los valores promedios de las concentraciones plasmáticas de retinol fueron de 0,46 ± 0,09 μg/ml (rango de 0,18 a 0,69 μg/ml). En invierno se observan los valores más bajos 0,42 ± 0,09 μg/ml (rango 0,18 a 0,57 μg/ml)y en primavera los más altos 0,50 ± 0,09 μg/ml (rango 0,29 a 0,69 μg/ml). Los valores promedio de concentraciones plasmáticas de retinol, obtenidos en este estudio, son los primeros datos presentes en Chile en bovinos mantenidos a pastoreo
Concentraciones séricas de triyodotironina, tiroxina y perfil lipídico en bovinos lecheros alimentados con una ración con bajo contenido de selenio Serum concentrations of triiodothyronine, thyroxine and lipid profile in dairy cows fed with a low selenium diet
R Matamoros,A Ceballos,PA Contreras,C Quiroga
Archivos de medicina veterinaria , 2008,
Abstract: El objetivo de este estudio fue evaluar el efecto de un bajo consumo de Se y su suplementación sobre la concentración sérica de T3 y T4 y sobre el perfil lipídico en vacas lactantes bajo estrés oxidativo inducido. Fueron seleccionadas 12 vacas Frisón Negro gestantes, asignadas auno de dos grupos homogéneos, control (n = 6, Se-D) y tratado (n = 6, Se-S) con selenato de bario (BaSe0(4)), ambos recibieron una ración Se-deficiente (el Se en base seca fue 0,03 ppm para la dieta preparto y 0,05 ppm para la dieta posparto) y sebo oxidado (0,5 kg/vaca/día). El grupo Se-S se suplemento con (1 mg Se/kg) bajo la forma de BaSe0(4) (1 mL/50 kg, s.c). Previo a la suplementación y cada 15 días, se tomaron muestras de sangre heparinizada y sin anticoagulante mediante venopunción coccígea. Se evaluó la actividad de glutatión peroxidasa (GSH-Px, EC 1.15.1.9), además la concentración sérica de T3 y T4, colesterol total, lipoproteínas (HDL, LDL y VLDL) y triacilgliceroles (TAG). La significancia se estableció empleando un PROC MIXED de S AS mediante la opción REPEATED, considerándose significativo P < 0,05. La suplementación con BaSe0(4) no produjo cambios en la producción de leche entre los grupos (P > 0,05), y la actividad de GSH-Px aumentó significativamente en el grupo Se-S a partir de 45 días postsuplementación (P < 0,05), la actividad en el grupo Se-D se mantuvo baja a lo largo del estudio (P < 0,05). No hubo diferencias para T3 y T4 (P > 0,05). La concentración de colesterol, LDL, VLDL y TAG fue similar entre los grupos (P > 0,05), siendo la concentración de HDL levemente mayor en el grupo Se-D (P = 0,047). Los resultados permiten se alar que una dieta baja en Se no indujo cambios en la función tiroidea o en el metabolismo de las lipoproteínas, excepto una mayor concentración de HDL, lo que en el bovino requiere la realización de estudios posteriores The aim of this study was to evaluate the effect of a low Selenium diet and its supplementation on the serum levels of T3, T4 and on the lipid profile in dairy cows under an induced oxidative stress. Twelve pregnant dairy Chilean-Friesian cows were selected and assigned to one of two groups, control (n = 6, Se-D) and treated (n = 6, Se-S) with barium selenate (BaSe0(4)), both receiving a Selenium-deficient diet (based on a 0.03 ppm Se-content of the DM in the diet before calving, and 0.05 ppm after calving) and oxidized tallow (0.5 kg/cow/day). The Se-S group was supplemented with selenium (1 mg/kg) in the form of BaSe0(4) (1 mL/50 kg, s.c). Prior to the supplementation and every 15 days, heparinized blood and plain bloo
Concentraciones séricas de triyodotironina, tiroxina y perfil lipídico en bovinos lecheros alimentados con una ración con bajo contenido de selenio
Matamoros,R; Ceballos,A; Contreras,PA; Quiroga,C; Andaur,M; Wittwer,F;
Archivos de medicina veterinaria , 2008, DOI: 10.4067/S0301-732X2008000100003
Abstract: the aim of this study was to evaluate the effect of a low selenium diet and its supplementation on the serum levels of t3, t4 and on the lipid profile in dairy cows under an induced oxidative stress. twelve pregnant dairy chilean-friesian cows were selected and assigned to one of two groups, control (n = 6, se-d) and treated (n = 6, se-s) with barium selenate (base04), both receiving a selenium-deficient diet (based on a 0.03 ppm se-content of the dm in the diet before calving, and 0.05 ppm after calving) and oxidized tallow (0.5 kg/cow/day). the se-s group was supplemented with selenium (1 mg/kg) in the form of base04 (1 ml/50 kg, s.c). prior to the supplementation and every 15 days, heparinized blood and plain blood samples were taken by venous puncture. the blood activity of glutathione peroxidase (gsh-px, ec 1.15.1.9) was evaluated, also the serum concentrations of t3, t4, total cholesterol, lipoproteins (hdl, ldl and vldl) and triacylglycerols (tag). the differences were settled by means of a proc mixed of sas, and the option repeated, significance was set at p < 0.05. the se-supplementation with base04 did not produce changes in the milk yield (p > 0.05), and the blood activity of gsh-px was higher in the group se-s starting 45 days after supplementation (p < 0.05), while the activity in the group se-d was lower along the study (p < 0.05). there were no differences for t3 and t4 (p > 0.05). serum concentration of cholesterol, ldl, vldl and tag were similar between groups (p > 0.05), there was a tendency to a higher concentration of hdl in the non-supplemented group (p = 0.047). the results suggested that a low se-diet does not induce changes in either the thyroid function or the serum concentration of cholesterol and lipoproteins, except for the concentration of hdl, being further studies in dairy cows necessary
Evaluation of Activity Patterns in Quinpirole-Treated Rats  [PDF]
Carlos L. Paíno
Journal of Behavioral and Brain Science (JBBS) , 2014, DOI: 10.4236/jbbs.2014.47030
Abstract: The present study aims to evaluate in rats the activity changes associated to treatments with D2-like receptor agonists using a simple behavioral procedure. Rats receiving a single dose of 1 mg/kg quinpirole or vehicle were scored for 6 spontaneous behaviors at different post-injection times. In each time point, the animals were placed in testing cages for 12 min and video-recorded during the last 2 min. The number of forelimb steps and the time spent sniffing were significantly increased by 15 min post-injection in the quinpirole group. Forelimb steps remained increased for at least 24 h. Scores of time spent sniffing, as well as time inactive and number of hindlimb steps appeared greatly altered at 90 and 180 min, but not at later time points. By 48 h, no differences between control and quinpirole-treated rats were observed. In conclusion, the simple behavioral procedure here proposed—or adaptations of it—provides a sensitive test to evaluate the time course of the effects of D2-like receptor agonists on rat spontaneous activity. Additionally, this test takes into account context-dependent sensitization. It can be adapted to different treatment conditions. This methodology would be useful for the preclinical screening of D2-like receptor drugs, using reduced numbers of animals to test those doses and treatment schedules producing less side-effects.
An Alternative View to the Cause of Market Failures: A Dynamic Approach  [PDF]
Salvador Contreras
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.47069
Abstract:

This paper presents an alternative view to the cause and size of market failures. The work here suggest that the size of the market failure is not man made per se but rather given a full set of initial conditions it is endogenous to the dynamical forces at play. It is shown that the level and variance of market failures is tied to the location of the steady state (i.e. level of development). The paper finds that only changes to the location of the steady state produces changes to the potential level of the market failure. This paper adds to the increasing body of literature the notion that institutional change is not a sufficient condition to sustained economic development.

Penile ectopic testis: experience of an adolescent
PA Ongom
East and Central African Journal of Surgery , 2011,
Abstract: This report describes a case of a penile ectopic testis a 14 years old. The condition had been present since birth. Social reasons hampered earlier referral for appropriate medical care. There had been progressive penile development, in association with a swelling, and normal secondary sexual characteristics. The scrotum was well developed on the right side. The right testis and spermatic cord were normal in size and position. The left scrotum was empty. There was an ovoid mass (the left testis) at the right (contralateral), dorsal, proximal half of the penile shaft. It was normal in size with a palpable spermatic cord. An ultrasound scan confirmed these findings. Surgical exploration and mobilization of the ectopic testis was done through a left inguinal incision. A gubernaculum was present. Colle’s fascia of the left scrotum was dissected. A left scrotal incision was used to anchor (orchidopexy) the left testis in a sub-Dartos pouch. Postoperative recovery was normal. It was concluded that a penile ectopic testis, normal in size, may present during adolescence. The condition is correctible though there is need for screening and early detection in children through national Health Policy interventions. East and Central African Journal of Surgery. 2011 Nov/ December;16 (3)
Environmental ethics: An African understanding
PA Ojomo
African Journal of Environmental Science and Technology , 2011,
Abstract: Global concerns about the current environmental crisis have culminated into some controversial environmental ethical theories, that is, normative environmental ethics, sentientist ethics, biocentric ethics, ecocentric ethics and eco-feminist ethics. One of the fundamental underlying features connecting these environmental ethical theories is their grounding in Western perspectives and cultural experiences. Given that environmental concerns are global concerns, and that the imperative of environmental ethics is challenging those life-threatening concerns, critical explorations of environmental ethics need to go beyond the Western horizon. But with respect to the African perspective to environmental ethics and the people’s cultural understanding of the environmental crisis, little has been done in this penultimate area. However, Segun Ogungbemi and Godfrey Tangwa have pioneered philosophical discussions on environmental ethics from an African vantage point. Hence, Ogungbemi defends what he calls “ethics of nature-relatedness,” while Tangwa proposes “ecobio-communitarianism” as a definitive theory of an African orientation to environmental ethics. This paper is therefore a contribution to the consolidation of an African orientation to environmental ethics through a critique and reconstruction of some of the misrepresentations of the African perspective to the environment, implicit in the arguments of Ogungbemi and Tangwa.
The use of traps and the need for conservation of Synodontis fisheries in Asa Lake, Ilorin, Nigeria
PA Araoye
African Journal of Biotechnology , 2009,
Abstract: The basket conical traps are commonly used to catch Synodontis species by the fishermen in Asa Lake, Ilorin, Nigeria because these species are caught alive to attract higher market values. Fleets of these traps randomly set at the bottom shoreline by fishermen at three different locations around the lake from the dam site to the river source were examined for Synodontis catch in 12 months. The specimen of Synodontis schall and Synodontis gambiensis were encountered with the latter occurring in August to October corresponding only with the flood season around the lake. S. schall occurred throughout the seasons but more abundantly in the traps during the dry season. All the specimens of Synodontis caught were found alive with mean standard length ranging from 7.8 to 16.75 cm for S. schall and 16.8 to 22.48 for S. gambiensis. Their corresponding weights ranges are 12.50 to 77.45 g and 49.75 to 92.76, for S. schall and S. gambiensis, respectively. Gravid specimens of both species were caught between the months of June to August in both the fixed and the lost traps. A total of 18 lost traps were recovered during the 12 months of research particularly during the flood seasons. There were no lost traps in November to March. The period of low catch (October and November) also corresponded with the season when the juveniles of S. schall became abundant in the lake. The total fish catch in the wet and dry season was significantly different (P<0.05) in both species. ‘Ghost fishing’ a phenomenon that usually occurred when the set traps were lost due to high floods around the lake and the need for conservation of these valuable water resources are discussed.
Manipulating legume/cereal mixtures to optimize the above and below ground interactions in the traditional African cropping systems
PA Ndakidemi
African Journal of Biotechnology , 2006,
Abstract: The purpose of mixing legume and cereals in the cropping systems is to optimise the use of spatial, temporal, and physical resources both above- and below ground, by maximising positive interactions (facilitation) and minimising negative ones (competition) among the components. The complex interactions in legume/cereal cropping systems such as those used by traditional farmers have received little research attention. Information from such studies is likely to provide an understanding of plant survival strategies when subjected to stress in mixtures. Current knowledge on how plants in mixtures change their biological and chemical environments and the potential benefits associated with such processes are assessed in this review.
Page 1 /4063
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.