Acides gras conjugués : effets biologiques et intérêt pour moduler la synthèse des matières grasses du lait chez la vache

Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2009-2010L'ajout de certains acides linoléiques conjugués (ALC) dans l'alimentation diminue la synthèse du gras du lait chez la vache. Les ALC alimentaires peuvent cependant être hydrogénés par les microorganismes du rumen. La formation de sels de calcium est considérée comme une méthode pour prévenir l'hydrogénation des ALC au cours de leur passage dans le rumen. Afin de déterminer les effets des ALC sous forme inerte sur la production et la composition du lait et sur le profil métabolique sanguin en conditions commerciales, 240 vaches laitières provenant de 8 troupeaux québécois ont été réparties selon un dispositif en blocs, selon la date de vêlage. Les traitements consistaient en quatre différentes doses d'ALC (0, 8, 16 et 32 g/j) distribuées de façon aléatoire à l'intérieur de chaque bloc. La production de gras a été diminuée de 11, 20 et 28 %, et la teneur en gras diminuée de 13, 22 et 28 % par rapport au témoin lorsque les animaux ont reçu 8, 16 et 32 g/j d'ALC (effet linéaire : P 0,15). Ces résultats démontrent que les mécanismes expliquant les effets inhibiteurs du 18:2 trans-10, cis-12 sur la lipogenèse du tissu mammaire sont différents de ceux rencontrés dans les autres tissus de l'organisme. Dans plusieurs situations où une chute de gras du lait est observée, celle-ci est beaucoup plus importante que celle prédite par la concentration en 18:2 trans-10, cis-12 du lait. Ces observations suggèrent que d'autres acides gras intermédiaires de la biohydrogénation puissent être impliqués dans le syndrome de chute de gras du lait. L'objectif du troisième volet de cette étude était d'évaluer les effets d'une perfusion intraveineuse de deux isomères de 18:3 diènes conjugués (DC; 18:3 cis-9, trans-11, cis-15 et 18:3 cis-9, trans-13, cis-15), lesquels constituent deux intermédiaires de la biohydrogénation ruminale de l'acide a-linolénique (AAL), sur la synthèse de la matière grasse laitière. Trois vaches Holstein multipares ont été réparties dans un dispositif en carré latin 3x3. Au cours des 5 premiers jours de chaque période, les vaches recevaient, via une perfusion intraveineuse, une emulsion lipidique 15 %, fournissant : 1) 18:3 cis-9, trans-11, cis-15 + 18:3 cis-9, trans-13, cis-15 + 18:2 trans-10, cis-12 (18:3 DC + JALC); 2) 18:3 cis-9, cis-12, cis-15 + 18:2 cis-9, cis-12 comme témoin (AAL + AL); ou 3) 18:3 cis-9, cis-12, cis-15 + 18:2 trans-10, cis-12, comme témoin positif (AAL + ALC). La consommation volontaire de matière sèche, la production laitière et la teneur en protéines n'ont pas été affectées par les traitements (P > 0,10). À la fin de la période expérimentale, la teneur en gras du lait était diminuée de 7 % pour les vaches recevant les traitements AAL + ALC ou 18:3 DC + ALC comparativement à celles recevant le traitement témoin (AAL + AL; P < 0,05). L'effet du traitement 18:3 DC + ALC sur la teneur en matières grasses du lait n'était attribuable qu'au contenu en 18:2 trans-10, às-12 du supplément perfusé. Les résultats de cette étude n'offre donc aucun support quant à une possible implication des isomères de 18:3 cis-9, trans-11, cis-15 et 18:3 cis-9, trans-13, cis-15 dans le syndrome de chute de gras du lait. Finalement, la forme des lipides influence leur absorption à travers la paroi intestinale. L'objectif de cette dernière étude était d'évaluer le coefficient de bioaccessibilité des acides gras d'un lait enrichi en 18:2 cis-9, trans-11 à l'aide du modèle gastro-intestinal dynamique in vitro TIM-1 (TNO, Zeist, The Netherlands). Le lait enrichi en 18:2 cis-9, trans-11 a été recueilli d'une vache Holstein recevant 4 % d'huile de carthame dans sa ration. Les autres traitements étaient constitués de 18:2 cis-9, trans-11 synthétiques sous forme d'acides gras libres ou de triacylglycérols, incorporés sous forme d'émulsion à un lait à faible teneur en 18:2 cis-9, trans-11. Le chyme excrété du compartiment iléal a été analysé pour sa composition en acides gras ainsi que la distribution des différentes classes de lipides. Les résultats ont révélé que la bioaccessibilité des acides gras s'élevait à 81,8 ± 3,1 % (P = 0,97). Le degré d'absorption des acides gras saturés était inversement proportionnel à la longueur de leur chaîne carbonée (effets linéaire et quadratique : P < 0,01). La bioaccessibilité était plus grande pour les acides gras insaturés que pour leurs équivalents saturés (P < 0,01). Enfin, la bioaccessibilité du 18:2 cis-9, trans-11 était la même pour tous les traitements et s'élevait à 87,0 ± 3,4 % (P = 0,99). Les résultats suggèrent que la distribution régiospécifique du 18:2 cis-9, trans-11 sur la structure du triacylglycérol n'influence pas sa disponibilité pour une absorption ultérieure à travers la membrane intestinale. De plus, cette étude aura permis de déterminer que le modèle gastrointestinal dynamique in vitro utilisé constitue un moyen efficace d'obtenir de l'information utile sur la digestibilité des acides gras chez l'humain

Abortion Decisions as Humanizing Acts: The Application of Ambivalent Sexism and Objectification to Women-Centered Anti-Abortion Rhetoric

Women-centered anti-abortion rhetoric, grounded in ostensibly positive beliefs that pregnant people are precious objects who must be protected from having abortions, has proliferated anti-abortion activism and legislation. However, abortion stigma, marked by negative perceptions of people who terminate pregnancies, is the most widely used theoretical tool for understanding the social and psychological implications of abortion. In this article, we first integrate these two seemingly contradictory perspectives on abortion through the lens of ambivalent sexism theory. We then argue that ambivalent sexism paves the way for objectifying perceptions and treatment of pregnant people; specifically, our typology of reproductive objectification provides a tool for exploring how the abortion decision-making of pregnant people is undermined. Through this lens, abortion decisions can represent a subversion of these portrayals and treatment by affirming people who seek and have abortions as whole human beings. Throughout, we aim to counter White supremacy and cisheteropatriarchy, which have marked public discourse and psychological research on abortion. Finally, using this reproductive objectification framework, recommendations for clinicians and researchers are provided

Voluntary exercise-induced changes in β2-adrenoceptor signalling in rat ventricular myocytes

Regular exercise is beneficial to cardiovascular health. We tested whether mild voluntary exercise training modifies key myocardial parameters [ventricular mass, intracellular calcium ([Ca2+]i) handling and the response to β-adrenoceptor (β-AR) stimulation] in a manner distinct from that reported for beneficial, intensive training and pathological hypertrophic stimuli. Female rats performed voluntary wheel-running exercise for 6–7 weeks. The mRNA expression of target proteins was measured in left ventricular tissue using real-time reverse transcriptase-polymerase chain reaction. Simultaneous measurement of cell shortening and [Ca2+]i transients were made in single left ventricular myocytes and the inotropic response to β1- and β2-AR stimulation was measured. Voluntary exercise training resulted in cardiac hypertrophy, the heart weight to body weight ratio being significantly greater in trained compared with sedentary animals. However, voluntary exercise caused no significant alteration in the size or time course of myocyte shortening and [Ca2+]i transients or in the mRNA levels of key proteins that regulate Ca2+ handling. The positive inotropic response to β1-AR stimulation and the level of β1-AR mRNA were unaltered by voluntary exercise but both mRNA levels and inotropic response to β2-AR stimulation were significantly reduced in trained animals. The β2-AR inotropic response was restored by exposure to pertussis toxin. We propose that in contrast to pathological stimuli and to beneficial, intense exercise training, modulation of Ca2+ handling is not a major adaptive mechanism in the response to mild voluntary exercise. In addition, and in a reversal of the situation seen in heart failure, voluntary exercise training maintains the β1-AR response but reduces the β2-AR response. Therefore, although voluntary exercise induces cardiac hypertrophy, there are distinct differences between its effects on key myocardial regulatory mechanisms and those of hypertrophic stimuli that eventually cause cardiac decompensation

Hiding or hospitalising? On dilemmas of pregnancy management in East Cameroon

Current international debates and policies on safe motherhood mainly propose biomedical interventions to reduce the risks during pregnancy and delivery. Yet, the conceptualisations of risk that underlie this framework may not correspond with local perceptions of reproductive dangers; consequently, hospital services may remain underutilised. Inspired by a growing body of anthropological literature exploring local fertility-related fears, and drawing on 15 months of fieldwork, this paper describes ideas about risky reproduction and practices of pregnancy protection in a Cameroonian village. It shows that social and supernatural threats to fertility are deemed more significant than the physical threats of fertility stressed at the (inter)national level. To protect their pregnancies from those social and supernatural influences, however, women take very physical measures. It is in this respect that biomedical interventions, physical in their very nature, do connect to local methods of pregnancy management. Furthermore, some pregnant women purposefully deploy hospital care in an attempt to reduce relational uncertainties. Explicit attention to the intersections of the social and the physical, and of the supernatural and the biomedical, furthers anthropological knowledge on fertility management and offers a starting point for more culturally sensitive safe motherhood interventions

Resisting the mantle of the monstrous feminine : women's construction and experience of premenstrual embodiment

The female reproductive body is positioned as abject, as other, as site of defciency and disease, the epitome of the ‘monstrous feminine.’ Premenstrual change in emotion, behavior or embodied sensation is positioned as a sign of madness within, necessitating restraint and control on the part of the women experiencing it (Ussher 2006). Breakdown in this control through manifestation of ‘symptoms’ is diagnosed as PMS (Premenstrual Syndrome) or PMDD (Premenstrual Dysphoric Disorder), a pathology deserving of ‘treatment.’ In this chapter, we adopt a feminist material-discursive theoretical framework to examine the role of premenstrual embodiment in relation to women’s adoption of the subject position of monstrous feminine, drawing on interviews we have conducted with women who self-diagnose as ‘PMS sufferers.’ We theorize women’s self-positioning as subjectifcation, wherein women take up cultural discourse associated with idealized femininity and the reproductive body, resulting in self-objectifcation, distress, and self-condemnation. However, women can resist negative cultural constructions of premenstrual embodiment and the subsequent self-policing. We describe the impact of women-centered psychological therapy which increases awareness of embodied change, and leads to greater acceptance of the premenstrual body and greater self-care, which serves to reduce premenstrual distress

Implications for sequencing of biologic therapy and choice of second anti-TNF in patients with inflammatory bowel disease:results from the IMmunogenicity to Second Anti-TNF therapy (IMSAT) therapeutic drug monitoring study

BACKGROUND: Anti-drug antibodies are associated with treatment failure to anti-TNF agents in patients with inflammatory bowel disease (IBD).AIM: To assess whether immunogenicity to a patient's first anti-TNF agent would be associated with immunogenicity to the second, irrespective of drug sequence METHODS: We conducted a UK-wide, multicentre, retrospective cohort study to report rates of immunogenicity and treatment failure of second anti-TNF therapies in 1058 patients with IBD who underwent therapeutic drug monitoring for both infliximab and adalimumab. The primary outcome was immunogenicity to the second anti-TNF agent, defined at any timepoint as an anti-TNF antibody concentration ≥9 AU/ml for infliximab and ≥6 AU/ml for adalimumab.RESULTS: In patients treated with infliximab and then adalimumab, those who developed antibodies to infliximab were more likely to develop antibodies to adalimumab, than patients who did not develop antibodies to infliximab (OR 1.99, 95%CI 1.27-3.20, p = 0.002). Similarly, in patients treated with adalimumab and then infliximab, immunogenicity to adalimumab was associated with subsequent immunogenicity to infliximab (OR 2.63, 95%CI 1.46-4.80, p &lt; 0.001). For each 10-fold increase in anti-infliximab and anti-adalimumab antibody concentration, the odds of subsequently developing antibodies to adalimumab and infliximab increased by 1.73 (95% CI 1.38-2.17, p &lt; 0.001) and 1.99 (95%CI 1.34-2.99, p &lt; 0.001), respectively. Patients who developed immunogenicity with undetectable drug levels to infliximab were more likely to develop immunogenicity with undetectable drug levels to adalimumab (OR 2.37, 95% CI 1.39-4.19, p &lt; 0.001). Commencing an immunomodulator at the time of switching to the second anti-TNF was associated with improved drug persistence in patients with immunogenic, but not pharmacodynamic failure.CONCLUSION: Irrespective of drug sequence, immunogenicity to the first anti-TNF agent was associated with immunogenicity to the second, which was mitigated by the introduction of an immunomodulator in patients with immunogenic, but not pharmacodynamic treatment failure

Implications for sequencing of biologic therapy and choice of second anti-TNF in patients with inflammatory bowel disease:results from the IMmunogenicity to Second Anti-TNF therapy (IMSAT) therapeutic drug monitoring study

BACKGROUND: Anti-drug antibodies are associated with treatment failure to anti-TNF agents in patients with inflammatory bowel disease (IBD).AIM: To assess whether immunogenicity to a patient's first anti-TNF agent would be associated with immunogenicity to the second, irrespective of drug sequence METHODS: We conducted a UK-wide, multicentre, retrospective cohort study to report rates of immunogenicity and treatment failure of second anti-TNF therapies in 1058 patients with IBD who underwent therapeutic drug monitoring for both infliximab and adalimumab. The primary outcome was immunogenicity to the second anti-TNF agent, defined at any timepoint as an anti-TNF antibody concentration ≥9 AU/ml for infliximab and ≥6 AU/ml for adalimumab.RESULTS: In patients treated with infliximab and then adalimumab, those who developed antibodies to infliximab were more likely to develop antibodies to adalimumab, than patients who did not develop antibodies to infliximab (OR 1.99, 95%CI 1.27-3.20, p = 0.002). Similarly, in patients treated with adalimumab and then infliximab, immunogenicity to adalimumab was associated with subsequent immunogenicity to infliximab (OR 2.63, 95%CI 1.46-4.80, p &lt; 0.001). For each 10-fold increase in anti-infliximab and anti-adalimumab antibody concentration, the odds of subsequently developing antibodies to adalimumab and infliximab increased by 1.73 (95% CI 1.38-2.17, p &lt; 0.001) and 1.99 (95%CI 1.34-2.99, p &lt; 0.001), respectively. Patients who developed immunogenicity with undetectable drug levels to infliximab were more likely to develop immunogenicity with undetectable drug levels to adalimumab (OR 2.37, 95% CI 1.39-4.19, p &lt; 0.001). Commencing an immunomodulator at the time of switching to the second anti-TNF was associated with improved drug persistence in patients with immunogenic, but not pharmacodynamic failure.CONCLUSION: Irrespective of drug sequence, immunogenicity to the first anti-TNF agent was associated with immunogenicity to the second, which was mitigated by the introduction of an immunomodulator in patients with immunogenic, but not pharmacodynamic treatment failure