Blood polymorphonuclear leukocyte chemotaxis during experimental escherichia-coli bovine mastitis.

The relationship between the severity of experimental Escherichia coli mastitis and the chemotactic response of blood polymorphonuclear leukocytes was investigated before and during mastitis. Experimental E. coli mastitis was induced in 10 healthy cows by inoculation of the rear right quarters with 10(3) cfu of E. coli. Cows were classified into two groups based on the severity of the mastitis. Bacterial growth in the inoculated quarter was used as parameter that indicated severity. Before and during experimental mastitis, the chemotactic response and the number of circulating polymorphonuclear leukocytes were greater for the moderately diseased cows than for the severely diseased cows. During the first 24 h of the experimental mastitis, the chemotactic response of polymorphonuclear leukocytes decreased in both groups. Recovery of the chemotactic response of white blood cells was more rapid in moderately diseased cows than in severely diseased cows. Possibly, the larger proportion of band neutrophils (the less chemotactically active band neutrophils) partially accounts for the lower chemotactic response of the circulating polymorphonuclear leukocytes during experimental mastitis in the severely diseased cows

Велес – повелитель мертвих

In providing advice on herd health, veterinarians need to be aware of farmers' goals and priorities. To determine the level of awareness, 29 veterinarians from 15 practices completed questionnaires during visits to dairy farms within the scope of veterinary herd health management (VHHM) programmes. The farmers (n = 30) were asked to complete a questionnaire and their discussions with the veterinarian were recorded using a voice recorder. Herd performance goals were set by the farmer and veterinarian in 24% of cases. Veterinarians who did not set goals indicated that they and the farmer 'intuitively knew' what each wanted to achieve, and that the setting of performance goals was considered 'too formal'. Veterinarians often could not identify a farmer's main goal, and typically found milk production and nutrition significantly more important (P <0.01, and P <0.02, respectively), and fertility significantly less important (P <0.01) than the farmers. During on-farm conversations, veterinarians did not actively seek to identify farmers' goals or problems, suggest a co-operative strategy or summarise any advice given. The findings of this survey suggest that veterinarians need to focus more on goal setting, since awareness of goals and priorities is important for both communication and compliance with advice given. The needs of farmers with respect to herd health should also be more actively sought by veterinarians as the findings indicate that most farmers do not readily volunteer such information. (C) 2013 Published by Elsevier Ltd

Influence of Ser and Thr residues in the geometry of transmembrane helices : implications on the structure and function of G protein-coupled receptors

Consultable des del TDXTítol obtingut de la portada digitalitzadaEn aquesta tesi s'apliquen eines bioinformàtiques a l'estudi de determinats sistemes biològics. En particular, l'estudi teòric de la influència de determinats aminoàcids sobre l'estructura i la dinàmica dels elements d'estructura secundària de les proteïnes s'aplica a la modelització per homologia dels receptors acoblats a proteïna G (GPCRs) i a l'estudi dels seus mecanismes d'activació. Se sap que determinats residus, com prolina, serina o treonina, provoquen distorsions locals en l'estructura de les hèlices a. L'anàlisi de bases de dades de seqüències de segments transmembrana mostra com certes combinacions d'aquests residus són més comunes que d'altres, i que algunes d'elles estan sobre-representades de manera significativa, mentre que d'altres estan clarament sots-representades. La restricció d'aquesta anàlisi de seqüències a la regió transmembrana dels GPCRs de la Classe A mostra com aquestes combinacions es troben en posicions específiques i, a més, es troben conservades en certes subfamílies de receptors. L'estructura i la dinàmica de les hèlices transmembrana que contenen aquestes combinacions de prolina i serina o treonina s'han estudiat mitjançant simulacions de dinàmica molecular en un entorn hidrofòbic explícit. Els resultats mostren com algunes d'aquestes combinacions indueixen distorsions importants en l'estructura de l'hèlix a, degut al seu efecte desestabilitzador de la xarxa de ponts d'hidrogen que dóna estabilitat a l'hèlix. Aquests resultats s'han aplicat a la construcció d'un model tridimensional del receptor de quimiocines CCR5 , utilitzant tècniques de modelització molecular per homologia. En aquest model es proposa que les hèlices transmembrana (TMH) 2 i 3 del receptor CCR5 són estructuralment diferents del patró de rodopsina. TMH2 està més doblegada degut a la presència d'un motiu Thr-X-Pro, que, a més, fa que aquesta hèlix es doblegui cap a TMH3. Així doncs, es proposa que, en aquest receptor, aquestes dues hèlices interaccionen. Aquesta interacció estaria mediada per la presència de residus hidrofòbics conservats i específics en les dues hèlices. Aquestes hipòtesis han estat posades a prova mitjançant experiments de mutagènesi dirigida, gràcies a la col·laboració amb l'Institut de Recherche Interdisciplinaire en Biologie Humaine et Nucléaire (IRIBHN), Université Libre de Bruxelles. Els resultats experimentals permeten establir la hipòtesi que la interfície TMH2-TMH3 participa en l'activació induïda per quimiocines del receptor CCR5. Com a conclusió, aquesta tesi pretén mostrar com, mitjançant la utilització d'eines bioinformàtiques, és possible traduir les seqüències primàries de proteïnes i les interaccions a nivell atòmic en estructures tridimensionals de proteïnes. A més, aquesta tesi mostra que, encara que l'estructura tridimensional de la rodopsina bovina és un patró útil per la modelització per homologia de GPCRs, s'han de tenir en compte de manera explícita les especificitats de seqüència de cada receptor per tal de construir models de receptors particulars. Aquestes especificitats de seqüència consisteixen en patrons de seqüència conservats en determinades famílies, que es tradueixen en divergències estructurals. Entre aquests patrons de seqüència, es proposa que els residus de serina i treonina, sols o combinats amb residus de prolina propers, poden modular la geometria de les TMHs, degut a la seva capacitat d'interferir amb la xarxa de ponts d'hidrogen que dóna estabilitat a les hèlices a. Finalment, es proposa que la influència dels motius de serina, treonina i prolina en l'estructura de les TMHs pot estar relacionada amb els processos d'activació dels GPCRs de la Classe A i, possiblement, d'altres proteïnes de membrana. En els GPCRs, aquests motius poden haver evolucionat per tal d'adaptar uns mecanismes d'activació conservats als lligands característics de cada família de receptors.This thesis is framed in the study of particular biological systems through the use of bioinformatics. In particular, the theoretical study of the influence of certain amino acids on the structure and dynamics of the secondary structure elements of proteins has been applied to homology modelling of G protein-coupled receptors (GPCRs) and to the study of their mechanisms of activation. Certain residues, as proline, serine or threonine, are known to induce local distortions in the a-helical structure. Analysis of sequence databases of transmembrane segments evidence that certain combinations of these residues are more common than others, and that some of them are significantly over-represented, while others are clearly under-represented. The focusing this sequence analysis on the transmembrane region of Class A GPCRs illustrates that these combinations are located in some specific locations and conserved within certain subfamilies of receptors. The structure and dynamics of transmembrane a-helices containing these combinations of proline and serine or threonine have been studied using molecular dynamics simulations in an explicit hydrophobic environment. The results show how some of these combinations induce significant distortions in the a-helical structure, due to their effect on the hydrogen bond network that stabilizes the helix. These results have been applied to the building of a three-dimensional model of the chemokine CCR5 receptor, using homology modelling techniques. In this model, transmembrane helices (TMH) 2 and 3 of CCR5 are proposed to be different from the bovine rhodopsin template. TMH2 is more bent due to the presence of a Thr-X-Pro motif, which, in turn, induces this helix to lean towards TMH3. As a consequence, an interaction between these two helices is proposed for this particular receptor. This interaction would be mediated through the presence of specific and conserved hydrophobic and aromatic residues in both helices. These hypothesis have been tested through site-directed mutagenesis experiments, thanks to a collaboration with the Institut de Recherche Interdisciplinaire en Biologie Humaine et Nucléaire (IRIBHN), Université Libre de Bruxelles. The experimental results let us to hypothesize that the TMH2-TMH3 interface is involved in the chemokine-induced activation of the CCR5 receptor. As a conclusion, this thesis aims to show how through the use of bioinformatics tools, primary sequences of proteins and interactions at an atomic level can be translated to three-dimensional protein structures. In addition, this thesis illustrates that, even though the three-dimensional structure of bovine rhodopsin is a very useful template for homology modelling of GPCRs, the sequence specificities of each receptor have to be explicitly taken into account in order to build models. These sequence specificities consist in sequence patterns conserved within certain families, which are translated into structural divergences. Among these sequence patterns, we hypothesize that serine and threonine, alone or combined with nearby proline residues, can modulate the geometry of TMHs, due to its capability to interfere with the hydrogen bond network that stabilize a-helices. Finally, we propose that the influence of serine, threonine and proline motifs in the structure of TMHs may be related to processes of activation in the Class A of GPCRs, and, possibly, other membrane proteins as well. In GPCRs, these motifs may have evolved in order to adapt a conserved mechanism of activation of the G protein to the cognate ligands of each receptor family

Preinfection chemotactic response of blood polymorphonuclear leukocytes to predict severity of Escherichia-coli mastitis.

Experimental mastitis was induced by inoculating rear right quarters of 10 healthy cows with 10(3) cfu of Escherichia coli. The chemotactic responses of peripheral blood polymorphonuclear leukocytes at d -6, -5, -2, -1, and immediately prior to inoculation were measured. Chemiluminescence of polymorphonuclear leukocytes was measured immediately prior to inoculation. Severity of the experimental mastitis was assessed by bacterial growth in the inoculated quarters. Results of this study indicated that severity of the experimental mastitis may be predicted by the chemotactic response in vitro of polymorphonuclear leukocytes isolated from the peripheral blood at d 2, d 1, and immediately prior to inoculation. The number of circulating polymorphonuclear leukocytes immediately prior to inoculation also showed a negative relationship with the severity of mastitis. No relationship existed between preinfection chemiluminescence of polymorphonuclear leukocytes and the severity of the experimental mastitis. Preinfection chemotactic response of polymorphonuclear leukocytes and preinfection numbers of circulating polymorphonuclear leukocytes appeared to be valuable as predictors of severity of experimental E. coli mastitis in cows

Severity of Experimental Escherichia coli Mastitis in Ketonemic and Nonketonemic Dairy Cows

The severity of experimental Escherichia coli mastitis in relation to in vitro chemotaxis of polymorphonuclear leukocytes was investigated in cows during negative energy balance. The negative energy balance was induced by feed restriction. Cows were classified into two groups, ketonemic and nonketonemic, based on the beta-hydroxybutyrate concentration in the peripheral blood at the moment of inoculation. Bacterial growth in the inoculated quarter was used as a parameter to indicate the severity of experimental mastitis. In the nonketonemic cows, experimental mastitis ranged from moderate to severe. Severity of experimental mastitis was negatively related to preinfection chemotactic response of polymorphonuclear leukocytes. In contrast, the course of experimental mastitis in the ketonemic group was relatively severe in all cows, regardless of preinfection chemotactic response

Characterization of Brain Lysosomal Activities in GBA-Related and Sporadic Parkinson’s Disease and Dementia with Lewy Bodies

Mutations in the GBA gene, encoding the lysosomal hydrolase glucocerebrosidase (GCase), are the most common known genetic risk factor for Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). The present study aims to gain more insight into changes in lysosomal activity in different brain regions of sporadic PD and DLB patients, screened for GBA variants. Enzymatic activities of GCase, β-hexosaminidase, and cathepsin D were measured in the frontal cortex, putamen, and substantia nigra (SN) of a cohort of patients with advanced PD and DLB as well as age-matched non-demented controls (n = 15/group) using fluorometric assays. Decreased activity of GCase (− 21%) and of cathepsin D (− 15%) was found in the SN and frontal cortex of patients with PD and DLB compared to controls, respectively. Population stratification was applied based on GBA genotype, showing substantially lower GCase activity (~ − 40%) in GBA variant carriers in all regions. GCase activity was further significantly decreased in the SN of PD and DLB patients without GBA variants in comparison to controls without GBA variants. Our results show decreased GCase activity in brains of PD and DLB patients with and without GBA variants, most pronounced in the SN. The results of our study confirm findings from previous studies, suggesting a role for GCase in GBA-associated as well as sporadic PD and DLB

Wie is de dierenarts?

De samenleving lijkt de huidige manier van houden en omgaan met dieren en het produceren van voedsel van dierlijke oorsprong niet meer te accepteren. Veranderingen zijn meer dan ooit nodig. Dierenartsen kunnen vanuit hun specifieke expertise een belangrijke bijdrage leveren aan deze ontwikkelingen. De diergeneeskundige beroepsgroep moet zich daarvoor wel verder ontwikkelen. Kremer pleit ervoor dat de dierenarts zich meer dan nu het geval is moet laten horen én waarmaken dat hij dé deskundige is wanneer het gaat om: grondige kennis van gezonde en zieke dieren en verantwoorde dierhouderij. De focus van de dierenarts verschuift daarbij van het genezen naar het gezond houden van dieren. Dat gebeurt nu nog te weinig volgens Kremer. Startcompetentie “De dierenarts voor landbouwhuisdieren wordt opgeleid met een startcompetentie voor de verschillende rollen in het veld, niet alleen als practicus op de boerderij. maar ook in de wetenschap, bij de overheid, bedrijfsleven of andere plekken in de voedselketen. Postacademische scholing is daarbij niet meer weg te denken. De faculteit kan en wil daarbij graag een rol spelen" aldus Kremer. Maatschappelijke verantwoordelijkheid “De nieuwe generatie dierenarts moet zich, meer dan nu het geval is, bewust zijn van zijn maatschappelijke verantwoordelijkheid en de maatschappelijke legitimiteit van het vak. De toekomstige dierenarts beschikt over autoriteit op basis van zijn persoon en deskundigheid. Hij of zij zal zich daarbij meer moeten profileren als de sleutelfiguur bij uitstek wanneer het gaat om deskundigheid op het gebied van diergezondheid, dierwelzijn en volksgezondheid. De opleiding tot dierenarts aan de faculteit Diergeneeskunde zal hier, nog meer dan nu de nadruk op moeten leggen. In de opleiding gaan we nog beter selecteren aan de poort om ervoor te zorgen dat de juiste personen de opleiding tot dierenarts gaan volgen. Daarnaast moet de opleiding ook haar onderwijscultuur veranderen. We leiden onze studenten op met uitstekende kennis en vaardigheden in de diergeneeskunde, maar we moeten ze tevens meer dan nu de nodige bagage meegeven op het gebied van persoonlijke vorming en ontwikkeling, zodat ze ook als persoon klaar zijn voor hun rol als onafhankelijke, analytische, ontwikkelingsgerichte en academisch gevormde deskundige. Dat zijn speerpunten als het gaat over opleiden aan een universiteit”, aldus de nieuwe hoogleraar

Veterinary herd health management programs on dairy farms in the Netherlands: Use, execution, and relations on farmers characteristics

Veterinary herd health management (VHHM) programs are of growing importance to the dairy industry; they support farmers in the shift from curative to preventive health management, caused by increased herd sizes and quality standards in dairy farming. Farmers participating in VHHM are visited every 4 to 6 wk by their veterinarian, who checks the animals and herd management to intervene in a proactive way with problems regarding animal health and animal welfare. At present, no good overview exists of how VHHM is executed on Dutch dairy farms, and whether different farmers require different types of VHHM. Aims of this study were to (1) map out how many farmers participate in VHHM, (2) describe how VHHM is executed on the farms, and (3) see whether certain farmer characteristics are related to farmers’ participation in VHHM. In 2011, a questionnaire was sent to 5,000 Dutch dairy farmers per e-mail. Part 1 of the questionnaire focused on participation in and execution of VHHM and part 2 focused on farmer characteristics regarding external information. Returned questionnaires (n = 1,013) were summarized and statistically analyzed. In this study 68.6% of the responding farmers participated in any form of VHHM. The most important activities were fertility checks and advice about fertility; the least important were housing and claw health. Relationships between farmer characteristics (use of and trust in information) and participation in VHHM were found

Фактори, що визначають концентрацію ¹³⁷Cs у рослині на забрудненому грунті в природних умовах

Проведено аналіз експериментальних даних за вмістом ¹³⁷Cs й K у рослинах та у відповідному грунтовому розчині в природних умовах на кількох ділянках у Зоні відчуження ЧАЕС, які розглядаються. В усі досліджувані рослини на всіх ділянках ¹³⁷Cs надходив переважно по низькоселективному катіонному каналу незалежно від складу грунтового розчину та вологості грунту. Якщо рослина не відчуває нестачі калію, K надходить у рослини переважно по низькоселективному каналу. При нестачі калію в рослині вона крім низькоселективного використовує також високоселективний канал надходження K. При цьому відбувається сильна дискримінація ¹³⁷Cs.Experimental data on the concentration of ¹³⁷Cs and K in plants and in the corresponding soil solution from several experimental sites under natural conditions in the Chornobyl Exclusion Zone are analyzed. All the investigated plants at all our experimental sites uptake ¹³⁷Cs mainly via low-affinity cation channels at any composition of the soil solution and the soil humidity. The plant uptakes potassium mainly via low-affinity cation channels if the plant has enough potassium. At the potassium starvation, the plant uses the high-affinity potassium channel for the potassium uptake as well. The high discrimination of ¹³⁷Cs is observed in this case