Evaluation of false positive results in microbial inhibitor tests for screening antibiotics in goat milk

Tesis por compendioGoat milk is primarily destined for the production of fermented products, in particular cheese. Therefore, the control of antibiotic residues in milk is of great importance, since these could have negative repercussions on technological properties of the milk as well as on the health of consumers. In milk quality control programs, microbial inhibitor tests are widely applied to detect antibiotics during the screening stage. However, tests are non-specific and may be affected by substances other than antimicrobials which could inhibit the growth of the test micro-organism, causing false positive results. The aim of this thesis was to evaluate the interference, related to the presence of different contaminants in goat milk, on the response of microbial inhibitor tests commonly used in Spain to detect antibiotics (BRT MRL, Delvotest SP-NT MCS and Eclipse 100 tests). The influence of the physicochemical characteristics of goat milk on the false positive outcomes in microbial screening tests was also investigated. The suitability of microbial inhibitor tests for screening antibiotics in colostrum secretions was studied by analysing antibiotic-free colostrum and milk samples from forty-three Murciano-Granadina goats, collected every 12 hours during the first week post-partum. Microbial inhibitor tests were not suitable for the analysis of goat colostrum because they presented a high percentage of doubtful and positive results (up 37.2% in the 36 hours after partum). To evaluate the effect of caprine colostrum on the microbial test response, antimicrobial-free goat milk spiked with different concentrations of colostrum was analysed to calculate the inhibitory concentrations producing 5% of positive results. The highest interferences were obtained for the addition of colostrum from 12 to 24 hours post-partum and the colostrum concentrations producing 5% positive results were between 5.1 and 34.6%. The BRT MRL was the test the most affected. In another study, the interference of detergents and disinfectants used for the cleaning of milking equipment and milk storage tanks of dairy farms was investigated. Antimicrobial-free goat milk was spiked with eight concentrations of different cleaning products (5 acid, 5 alkaline, 5 domestic washing-up liquids, and 1 disinfectant) and analysed using microbial screening tests. The presence of acid detergent and disinfectant based on sodium hypochlorite in goat milk did not affect the microbial test response. However, alkaline detergents at concentrations ≥ 1 ml/l could lead to false positive results in microbial inhibitor tests (up to 16.7%) and from 4 ml/l on 100% positive results were obtained. Regarding the products used for home use, and those used on farms and small size dairies, washing-up liquid containing sodium laureth sulphate and ethanol had the greatest effects on microbial inhibitor tests, even starting from a relatively low concentration (1 ml/l). On the other hand, the presence of a relatively low concentration of detergents in goat milk (0.5 ml/l) slightly modified the detection capability of the microbial inhibitor tests for amoxicillin, ampicillin, benzylpenicillin, and cloxacillin, although the detection of these drugs at MRL (safe level) was not compromised. Antiparasitic agent residues in goat milk could be another possible cause of false positive results in microbial screening tests. An in vitro study to evaluate the effect of seven parasiticides commonly used in dairy goats was carried out. Further two studies, where albendazole and ivermectin were applied to two groups of dairy goats in lactation were performed. It should be noted that the parasiticide ivermectin is banned for the treatment of animals producing milk for human consumption, although its inclusion in this study was considered interesting to understand the potential effect of their residues in milk, in the event the practice was performed illegally. In the in vitro study, raw antibiotic-free milk from goats was spiked individually with eight different concentrations of albendazole, closantel, diclazuril, febendazole, levamisole, diazinon, and ivermectin. The microbial inhibitor test results showed a great variability according to the test and the drug under study. Of the tests considered, the BRT MRL test was the most sensitive to antiparasitic agents, with the lowest concentrations of antiparasitic agent causing 5, 10, and 50% of positive results. Generally, closantel and diazinon were the antiparasitic agents that produced higher interferences in all tests, since low concentrations already resulted in positive results, while only higher concentrations of diclazuril and ivermectin showed an inhibitory effect. To evaluate the effect of albendazole residues on the microbial inhibitor test response, eighteen healthy Murciano-Granadina goats in mid-lactation were treated with a single oral administration of the commercially available albendazole registered for dairy sheep (7.5 mg/kg b.w. of active compound) with a withdrawal period of 4 days for milk production in ovine. Albendazole and its metabolite residues in goat milk after under cascade treatment were not detected above MRL from the third day post-administration. However, a high occurrence of non-compliant results was obtained for the BRT MRL test during the first six days after treatment, suggesting that factors related to the albendazole application other than the drug concentration are able to affect the microbial inhibitor test response in some cases. Regarding the ivermectin study, twenty-eight Murciano-Granadina goats infested with Sarcoptes scabiei var. caprae were treated with a subcutaneous injection of ivermectin (200 μg/kg b.w.), with a second dose applied seven days after the first treatment. Drug residues in goat milk were recorded during the first fifteen days of the experiment with concentrations ranging from 8.13 to 24.25 ng/ml. In addition, all the microbial screening tests seem to be affected by the ivermectin treatment, with BRT MRL the most affected (20%) compared with Delvotest SP-NT MCS and Eclipse 100 (6.6 and 5.7%, respectively). These positive results cannot be associated with the ivermectin concentration in goat milk, as the concentrations measured were lower than the inhibitory concentrations as reported in a previous in vitro study for these microbial tests. Thus, as suggested by some authors, interferences could be related to changes or alterations caused by the application of the parasiticide agent or by the parasitic disease itself, which could affect the immune response of the animals favouring the presence of inhibitory substances in milk. The study of the effect of the goat milk composition on the specificity (rate of false positive results) of microbial inhibitor tests for screening antibiotics was also considered. Thus, individual goat milk samples (n=200) were analysed by microbial inhibitor tests using both visual and instrumental classification of the test results. The highest specificity values were obtained for the instrumental interpretation of the test results (94-99% vs 90-96%) due to the occurrence of samples with intermediate colorations (green-yellow, yellow-blue) making the visual classification more difficult and subjective. A relation was found between positive results in BRT MRL and Eclipse 100 tests and an elevated fat content in the goat milk. Positive outcomes in Eclipse 100 were associated with the butyric acid concentration in the milk. Further, the Delvotest SP-NT MCS test response was affected by elevated pH values, high lactoferrrin and myristoleic acid concentrations in the goat milk. This percentage of positive results could be minimized by a pre-treatment prior to microbial inhibitor test analysis, such as fat removal by centrifugation (3,100 g for 10 min at 4 ºC) and/or heating (80 ºC for 10 min). Undoubtedly, improvements on the specificity of the microbial inhibitor tests for screening antibiotics in goat milk are desirable to avoid the destruction of milk compliant for human due to the occurrence of false positive results. The related financial losses affect farmers and dairies. However, it should be noted that the presence of contaminants in goat milk could be avoided by applying good farming practices designed to ensure that milk is obtained from healthy animals under proper hygienic conditions so ensuring the food safety of goat milk and related dairy products.Romero Rueda, T. (2015). Evaluation of false positive results in microbial inhibitor tests for screening antibiotics in goat milk [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48552TESISCompendi

Information and Communication Technologies (ICTS) as a Tool for Intercultural Education. A collaborative experience in secondary education in Tlapa de Comonfort, Guerrero, Mexico

This paper discusses the collaborative experience of creating educational materials for a secondary school in Tlapa de Comonfort, Guerrero, México. In this school, students from Nahuatl, Tun savi, Me'phaa and Spanish speaking communities live and learn together. The intercultural context provides challenges for science education that we sought to address. The use of collaborative technologies in science classes has made visible the cultural diversity in the classroom, helping students and teachers recognize themselves as active agents in the construction of common knowledge and in sharing their\ud knowledge. This experience also shows the importance of ICTs as technologies of expression that reinforce individual and collective identity in intercultural contexts

Cortical development associated with conjugation of Paramecium

The cortical cytoskeleton of Paramecium is characterized by a complex, polarized and asymmetrical organization. In order to analyse the cortical development of Paramecium tetraurelia during the sexual process of conjugation, different antibodies have been used to follow the development of five cortical components: basal bodies, ciliary rootlets, outer lattice, epiplasm and cytospindle. This study demonstrates that the cortex of Paramecium undergoes an elaborate development process following conjugation. Some of the cortical structures that are not renewed at any other moment of the cell cycle, are resorbed after conjugation and replaced by other newly formed ones. The reorganization of the cortical components occurs according to different morphogenetic waves that spread over the cell surface. The oral system and the preoral suture line act as morphogenetic epicentres.Junta de Andalucía y Departamento General de Investigación Científica y Técnica (DGICYT) PB91/062

Energy balance data from lactating dairy goats offered total mixed diets

[EN] The objective of the study was to develop a univariate model for analyzing energy balance data from lactating goats at mid lactation and determine maintenance requirements and partial efficiencies of energy utilization. Energy balance data from eight studies involving lactating Murciano-Granadina goats fed total mixed diets, which accounted for a variation in metabolizable energy (MEI) intake, milk energy output (EI), and tissue energy balance, were used. The database included records obtained by indirect calorimetry. Data were adjusted with a mixed model that included the study as a random effect. Then, two multivariate linear models were obtained: metabolizable and net energy models. The metabolizable model was MEI=ß0+ß2E1+ß3Tg+ß4T1+¿ and the net energy model was E1=ß0+ß1MEI+ß2Tg+ß3T1+¿; where ß0, ß1, ß2 and ß3 were the parameters, Tg was tissue energy retention and Tl the milk energy derived from body stores. For a better fitted proposed model, net energy for maintenance (NEm) was 283 kJ/kg of Body Weight 0.75 (BW) per day, and the efficiency of utilization of ME for lactation (k1), body weight gain (kg) and body tissue mobilization for milk production (kt) were 62%, 83% and 78%, respectively. Maintenance requirements and partial efficiencies for milk production and tissue energy mobilization were similar to the values proposed by INRA (2018). The increase in the efficiency of utilizing dietary energy for gain, compared with other feeding systems, was partially attributed to the stage of lactation, due to that goats were feeding at mid lactationFernández Martínez, CJ.; Romero Rueda, T. (2019). Energy balance data from lactating dairy goats offered total mixed diets. Open Journal of Animal Sciences (Online). 9(4):385-400. https://doi.org/10.4236/ojas.2019.94031S3854009

Arabidopsis thaliana DOF6 negatively affects germination in non-after ripened seeds and interacts with TCP14

Seed dormancy prevents seeds from germinating under environmental conditions unfavourable for plant growth and development and constitutes an evolutionary advantage. Dry storage, also known as after-ripening, gradually decreases seed dormancy by mechanisms not well understood. An Arabidopsis thaliana DOF transcription factor gene (DOF6) affecting seed germination has been characterized. The transcript levels of this gene accumulate in dry seeds and decay gradually during after-ripening and also upon seed imbibition. While constitutive over-expression of DOF6 produced aberrant growth and sterility in the plant, its over-expression induced upon seed imbibition triggered delayed germination, abscisic acid (ABA)-hypersensitive phenotypes and increased expression of the ABA biosynthetic gene ABA1 and ABA-related stress genes. Wild-type germination and gene expression were gradually restored during seed after-ripening, despite of DOF6-induced over-expression. DOF6 was found to interact in a yeast two-hybrid system andin planta with TCP14, a previously described positive regulator of seed germination. The expression of ABA1 and ABA-related stress genes was also enhanced in tcp14 knock-out mutants. Taken together, these results indicate that DOF6 negatively affects seed germination and opposes TCP14 function in the regulation of a specific set of ABA-related gene

VIE Project: Cultural values and socioeconomic factors as determinants of entrepreneurial intentions

This paper describes a research project currently being developed by the authors. It aims to analyse the role played by psychosocial, cultural and socioeconomic factors in shaping the entrepreneurial intention. Survey methods will be used on a population of potential entrepreneurs (having not yet performed actual entrepreneurial behaviours). In this sense, undergraduate students and individuals contacting business support centres will be considered as part of the sample. We expect to get a clearer understanding of the psychosocial elements, socioeconomic factors and cultural values affecting the venture-creation decision. The results would be important to policy makers (showing them what to encourage), to practitioners (what to do better), and to researchers (what to clarify)

RENDIMIENTO Y CALIDAD DE FORRAJE DE CUATRO CEREALES DE GRANO PEQUEÑO EN TRES ETAPAS DE CRECIMIENTO Y DOS NIVELES DE NITROGENO EN EL VALLE DE TOLUCA MEXICO

Tesis de licenciatura de Ia carrea de Ingeniero Agrónomo Fitotecnista en donde se estudió el efecto de la etapa de corte y la dosis de nitrógeno sobre el rendimiento y calidad nutricional de forraje en avena, cebada, triticale y trigoEn el valle de Toluca la producción de forraje se deriva principalmente de cultivos de cereales como son la avena y el maíz, establecidos bajo condiciones de temporal. Si bien la producción de forraje obtenida por estos cultivos cumple con la demanda para alimentación del ganado, no siempre está relacionado con la calidad nutricional requerida para optimizar dicho proceso. En el presente trabajo se evaluaron dos variedades de avena (Avemex y Karma), dos de cebada (Capuchona y Esmeralda), una variedad y una línea avanzada de triticale (Bicentenario y L3) y dos variedades de trigo (Baguette y Tollocan). El experimento se llevó a cabo en el ciclo primavera-verano 2015 en el valle de Toluca, México. La siembra se realizó el 26 de junio de 2015, con una densidad de siembra de 300 semillas por m2, bajo un diseño experimental de parcelas divididas en tiempo bajo un arreglo de bloques completos al azar con tres repeticiones, donde la parcela experimental constó de 4 surcos a doble hilera de 6 m de longitud con una separación de 80 cm entre surcos y 20 cm entre hileras. Se estudió el efecto de dos dosis de nitrógeno (60 y 120 kgN ha) y tres etapas fenológicas al corte (embuche, antesis y grano lechoso-masoso), sobre el rendimiento del forraje y algunos componentes de calidad nutricional en las tres etapas de corte mencionadas. La producción de materia seca y el contenido nutricional del forraje mejoró al aumentar la dosis de fertilización nitrogenada. El rendimiento de forraje se incrementó a medida que se retrasó la etapa de corte pero la calidad nutricional se vio disminuida conforme avanzó la madures de la planta. La L3 de triticale presentó mayor acumulación de biomasa en la etapa de grano lechoso-masoso (16.5 t ha-1), mientras que la variedad de trigo Baguette destacó en la etapa de embuche, ya que mostró el mejor comportamiento en los componentes de calidad nutricional de forraje, además de sobresalir por su alto contenido de proteína cruda incluso en la etapa de grano lechoso-masoso (103 g kg-1). Los resultados obtenidos indican que algunas de las variedades evaluadas pueden ser una opción viable para cumplir con la demanda de forraje con buena calidad para la alimentación de ganado lechero y de engorda en el valle de Toluca, México.UNIVERSIDAD AUTÓNOMA DEL ESTADO DE MÉXICO, FACULTAD DE CIENCIAS AGRÍCOLAS PROYECTO: Cambios en los Caracteres Ecofisiológicos del Rendimiento y Composición del Grano de Triticale en Función de la Disponibilidad de Nitrógeno Clave: 3793/2014/CI

Desarrollo de modelo didáctico de columnas filtrantes a partir de los requerimientos técnicos de los laboratorios del área de geotecnia e hidráulica

Trabajo de InvestigaciónEste proyecto se realizó con el fin de dotar los laboratorios de la Universidad Católica de Colombia para facilitar el aprendizaje del proceso de filtración por columnas filtrantes y sus diferentes capas granulares. Esta metodología, sirve para grupos de investigación, ya que se compone de capas granulométricas y se puede experimentar con demás materiales de filtración como son las diatomeas.43 p.INTRODUCCIÓN JUSTIFICACIÓN 1. ANTECEDENTES 2. OBJETIVOS 3. DELIMITACIÓN 4. METODOLOGÍA 5. PRODUCTO A ENTREGAR 6. CRONOGRAMA 7. PRESUPUESTO 8. MARCO CONCEPTUAL 9. MARCO TEÓRICO 10. CONCLUSIONES 11. RECOMENDACIONES 12. BIBLIOGRAFÍAPregradoIngeniero Civi

Escuela Superior de Hostelería y Restauración El Palmar

[ES] Ubicado en el pueblo de El Palmar, en pleno centro del Parque Natural de la Albufera. Un pueblo caracterizado por la cantidad de restaurantes que alberga y por un turismo masivo de sólo unas horas al día. Con esta intervención se pretende aumentar la actividad profesional y residencial de dicha zona. Para ello, se realizan pequeñas intervenciones urbanísticas a lo largo de todo el pueblo. Se potencia el eje izquierdo como el eje público, disponiendo arbolado y acondicionando terrazas de restaurantes. Por último, se colmata el pueblo con un conjunto edificado que alberga una escuela de hostelería. En la cual se impartirán los grados medios y superiores relacionados con la hostelería, así como también una zona destinada a la innovación e investigación culinaria.Rueda Romero, V. (2018). Escuela Superior de Hostelería en el Palmar. http://hdl.handle.net/10251/14077

Finite Element Simulation of a Bolted Steel Joint in Fire Using ABAQUS Program

The research on the performance of steel connections at elevated temperatures is of great importance for the understanding of structural collapses caused by fire; concerning fire safety in building design. The joints of any steel building are significant structural components, as they provide links between principal members. This study presents a detailed three-dimensional (3-D) finite element (FE) model of a steel endplate beam-to-column joint subjected to simulations at ambient and elevated temperatures. The model was defined using ABAQUS software, on the basis of experimental tests performed in Al-Jabri et al., 1999. Good agreement between simulations and experimental observations confirms that the finite element ABAQUS solver is suitable for predicting the behaviour of the structural steel joint in fire. Using the European standards (EN 1993-1-8, 2005), a component based model was also developed to predict the behaviour of the joint, and to compare against the FE model at both ambient and elevated temperatures. Comparison of the results provided a high level of accuracy between models, especially in the elastic zone. The validated FE model was used to conduct further studies with new 3D loading conditions in order to enhance the understanding of steel joints behaviour on fire. The Component Method model was extended and compared against ABAQUS model, providing useful results which enforced the use of this method on 3D. /Kir1