34 resultados para drugs and the hormones of male reproduction

em Deakin Research Online - Australia


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Although it is generally considered that stress can impair reproduction, we suggest that the impact of acute or repeated acute stress or acute or repeated acute elevations of cortisol are of little consequence in female pigs, even if these occur during the series of endocrine events that induce oestrus and ovulation. It is important to understand the impact of acute stress on reproduction because, in the intensive production of livestock, animals are often subjected to short-term challenges. There seems little doubt that reproduction in a proportion of female pigs is susceptible to impairment by severe and prolonged stress or the sustained elevation of cortisol but only when this continues for a substantial period. In female pigs, where reproduction is susceptible to impairment by severe prolonged stress, it is possible that the mediators of this suppression are cortisol, corticotrophin-releasing factor and vasopressin but, in pigs, there is evidence to suggest that adrenocorticotrophic hormone is not involved. Other substances secreted during stress may be involved but these are not considered in this review. It is possible that the mediators of stress act at any level of the hypothalamo-pituitary-ovarian axis. Although a variety of experimental manipulations have provided potential mediators and mechanisms for the stress-induced suppression of reproduction, these experimental manipulations rarely represented physiological circumstances so it is not clear if such mechanisms would be important in a physiological context. The precise mediators and mechanisms by which hormones released during stress may inhibit reproductive processes during severe prolonged stress are yet to be determined.

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Glucocorticoids hormones (GCs) are intuitively important for mediation of age-dependent vertebrate life-history transitions through their effects on ontogeny alongside underpinning variation in life-history traits and trade-offs in vertebrates. These concepts largely derive from the ability of GCs to alter energy allocation, physiology and behaviour that influences key life-history traits involving age-specific life-history transitions, reproduction and survival. Studies across vertebrates have shown that the neuroendocrine stress axis plays a role in the developmental processes that lead up to age-specific early life-history transitions. While environmental sensitivity of the stress axis allows for it to modulate the timing of these transitions within species, little is known as to how variation in stress axis function has been adapted to produce interspecific variation in the timing of life-history transitions. Our assessment of the literature confirms that of previous reviews that there is only equivocal evidence for correlative or direct functional relationships between GCs and variation in reproduction and survival. We conclude that the relationships between GCs and life-history traits are complex and general patterns cannot be easily discerned with current research approaches and experimental designs. We identify several future research directions including: (i) integration of proximate and ultimate measures, including longitudinal studies that measure effects of GCs on more than one life-history trait or in multiple environmental contexts, to test explicit hypotheses about how GCs and life-history variation are related and (ii) the measurement of additional factors that modulate the effects of GCs on life-history traits (e.g. GC receptors and binding protein levels) to better infer neurendocrine stress axis actions. Conceptual models of HPA/I axis actions, such as allostatic load and reactive scope, to some extent explicitly predict the role of GCs in a life-history context, but are descriptive in nature. We propose that GC effects on life-history transitions, survival probabilities and fecundity can be modelled in existing quantitative demographic frameworks to improve our understanding of how GC variation influences life-history evolution and GC-mediated effects on population dynamics Lay Summary Functional Ecology

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Pharmaceutical benefits provide a stable framework within which consumers, prescribers, suppliers, pharmacists and other actors undertake transactions. The state in effect delivers a good that enhances individual autonomy. A major reason for the legitimacy enjoyed by pharmaceutical benefits in both Australia and Sweden is that these programs have strong attributes of universalism (rather than targeting). Sweden's predominantly public health system allows greater scope for pharmaceutical policy innovation. Australia's Pharmaceutical Benefits Scheme (PBS), while historically resilient and effective, is now wedged precariously between traditional considerations of equity and public health on the one hand, and constant pressure for increased marketisation on the other.

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Environmental pollutants which alter endocrine function are now known to decrease vertebrate reproductive success. There is considerable evidence for endocrine disruption from aquatic ecosystems, but knowledge is lacking with regard to the interface between terrestrial and aquatic ecosystems. Here, we show for the first time that birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour. We found that male European starlings (Sturnus vulgaris) exposed to environmentally relevant levels of synthetic and natural estrogen mimics developed longer and more complex songs compared to control males, a sexually selected trait important in attracting females for reproduction. Moreover, females preferred the song of males which had higher pollutant exposure, despite the fact that experimentally dosed males showed reduced immune function. We also show that the key brain area controlling male song complexity (HVC) is significantly enlarged in the contaminated birds. This is the first evidence that environmental pollutants not only affect, but paradoxically enhance a signal of male quality such as song. Our data suggest that female starlings would bias their choice towards exposed males, with possible consequences at the population level. As the starling is a migratory species, our results suggest that transglobal effects of pollutants on terrestrial vertebrate physiology and reproduction could occur in birds.

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Developmental stress has recently been shown to have adverse effects upon adult male song structure in birds, which may well act as an honest signal of male quality to discriminating females. However, it still remains to be shown if females can discriminate between the songs of stressed and non-stressed males. Here we use a novel experimental design using an active choice paradigm to investigate preferences in captive female zebra finches (Taeniopygia guttata). Nine females were exposed to ten pairs of songs by previously stressed and non-stressed birds that had learned their song from the same tutor. Song pairs differed significantly in terms of song complexity, with songs of stressed males exhibiting lower numbers of syllables and fewer different syllables in a phrase. Song rate and peak frequency did not differ between stressed and non-stressed males. Females showed a significant preference for non-stressed songs in terms of directed perching activity and time spent on perches. Our results therefore indicate that developmental stress affects not only the structure of male song, but that such structural differences are biologically relevant to female mate choice decisions.

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The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae.

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Different cultures and the specific culture manifested within them are intrinsically linked to addiction in a complex fashion which has a long history. For important thinkers, such as Nietzsche, addiction actually embodies human culture, rendering addiction and culture inseparable. This is clearly seen within the Western world’s addiction to the consumption of material goods and the damage that results.

Utopia has often become dystopia. Not only is an understanding of addiction key to understanding culture but to an understanding of the very act thinking itself and the way of being in the world. Addiction raises key philosophical questions, such as: do people really have a choice in their behavior, and what governs them; is it free will or predetermination? Is it biology or environment is it the external world or the internal that drives addiction, or a complex combination of both?

In a contemporary context the media frenzy around celebrity addiction continually fuels public debate in this area, and this book deepens the understanding of addiction within this contentious context. This book addresses a key concern over how addiction became the norm, and it seeks to understand its dominance comprehensively. How did it come to pass that not being an addict was a transgressive act and way of being?

While there has been a great deal of debate about addiction utilizing the discourse of individual and often competing disciplines such as biology and psychology, little attention has been paid to the cultural aspects of addiction. The innovative approach taken by this book is to offer insights into this complex area through a contemporary methodology that covers diverse interrelated areas. Drawing on different disciplines, offering deeper insights, from the analysis of music lyrics to empirical social science and anthropological work in AA groups in Mexico and the portrayal of the “addiction’ to therapy in film and television, amongst other areas, this book addresses the need for a more comprehensive approach.

Academic analysis is also given to the discourse on celebrity culture and addiction. A contemporary fusion of the humanities and the social sciences is the best way forward to tackle this subject and move the debate on. The focus of this study is an innovative interdisciplinary and intercultural approach to addiction, from the social sciences to the humanities, including cultural studies, film and media studies, and literary studies. Areas that have been overlooked, such as lost women’s writings, are examined, in addition to comics, popular film and television, and the work of AA groups.

This edited collection is the first study to provide such a comprehensive analysis of the cultures of addiction. Traversing cultures across the globe, including Asia, Central America, as well as Europe and America, this book opens up the debate in addiction studies and cultural studies. The important insights the book delivers helps to answer questions such as: In what way can Deleuze further the understanding of addiction through the analysis of rock lyrics? How does anthropology improve the understanding of AA groups? How can cultural studies deepen knowledge on the “addiction” to therapy? These are just some of the vast array of areas this book covers. Other areas include the condemnation of “addiction” to comic reading through an historical examination, violence in popular culture, and lost women’s writing on addiction. No other book has such depth and contemporary breadth.

Cultures of Addiction is an important book for those taking cultural studies courses across a range of interrelated disciplines, including English and literary studies, history, American studies, and film and media studies. This will be invaluable to library collections in these fields and beyond in the social sciences, and specifically in addiction studies and psychology.

(Jason Lee, Editor)

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The movements and submergence behaviour of two male green turtles (Chelonia mydas) on their mating grounds at Ascension Island were investigated by satellite telemetry. During the mating season, males tended to conduct much shorter dives (typically <15 min) than those recorded previously for females during the internesting period at this rookery. This suggests that throughout the mating season males maintained relatively high activity levels, presumably associated with locating and mating with as many females as possible to maximise their reproductive output. At the end of their residence at the mating ground, the two males conducted longer dives (48 min and 21 min, respectively), suggesting that they rested before their migration away from the island. Although very few locations were obtained during this migration, those obtained showed that males migrate to South America, as has been shown previously for females from this population.

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This article considers the decision of the Family Court of Australia in Re Kevin (Validity of Marriage of a Transsexual) [2001] FamCA 1074, which was upheld by the Full Court of the Family Court of Australia in February 2003. Re Kevin was the first case in Australia to deal directly with the question of whether a transsexual person could marry under Australian law. In the past, Australia had adhered to the judgement of Ormrod J in Corbett v Corbett [1971] P. 83, which set the benchmark for what is ‘maleand what is ‘female’ under the common law. Prior to Re Kevin the question of what is a man and what is a woman for the purposes of marriage in Australia mirrored the strict biological test established in Corbett. In other words, the Australian courts relied upon biological factors, as espoused by Ormrod J, when determining a person's true sex. In Re Kevin, Chisholm J examined in detail what it is to be a man or woman, but unlike Ormrod J considered ‘brain sex’ to have a significant impact on a person's view of their own innate sexual identity. The Full Court of the Family Court agreed with the powerful and well-reasoned judgement of Chisholm J at first instance.

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The paper examines the wage structure in the Chinese state enterprise sector between 1981 and 1987. This period is of particular interest given the introduction of major labour market reforms in China during the early 1980s. In essence the reforms represented a movement away from administratively determined prices towards a market–oriented system combined with a relatively flexible system of labour allocation. The Juhn, Murphy and Pierce (1991) decomposition is employed to shed light on the role of changing labour market institutions over the period.

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Background Interventions that increase participation in physical activity and positive dietary changes may improve the health of the community through modifying the lifestyle contribution to preventable disease. However, previous evaluations have identified concerns about inequitable and unsustainable uptake, adherence and retention within healthy lifestyle schemes.

Intervention study The intervention evaluated here was designed to be a 12-week intervention for participants, offering free testing of physiological indicators of health, one-to-one health advice and a range of exercise, activity and cookery classes, at no or reduced cost, at local venues throughout the community. This paper reports the findings from a small qualitative study undertaken to explore the experiences and reflections of those who took part in the intervention to different extents, including those who fully and partially participated as well as those who dropped out or declined to take part.

Method Sixteen respondents took part in semi-structured interviews (5 male, 11 female; 8 black, 8 white; age range 25–85).

Findings The findings suggest that participants assessed the healthy lifestyle intervention in terms of how well it met their pre-existing needs and opportunities for change, and that they selected the aspects of the scheme that suited them, interested them and were perceived as delivering salient results. There is also evidence for a stronger role of perceived support in influencing uptake and maintenance of lifestyle changes, and that support was conceptualised by participants as one of the services offered by the scheme. Perceived support and related perceptions of reliance on the scheme to sustain lifestyle changes also suggested that in some cases full adherence to a scheme is not as likely to produce long-term adherence to lifestyle changes as compared to partial, but more realistic adherence and smaller lifestyle changes. Implications for delivering and evaluating healthy lifestyle interventions are also discussed.

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This article provides a synopsis of the new dynamics of the global biopharma industry. The emergence of global generics companies with capabilities approximating those of 'big pharma' has accelerated the blurring of boundaries between the innovator and generics sectors. Biotechnology-based products form a large and growing segment of prescription drug markets and regulatory pathways for biogenerics are imminent. Indian biopharma multinationals with large-scale efficient manufacturing plants and growing R&D capabilities are now major suppliers of Active Pharmaceutical Ingredients (APIs) and generic drugs across both developed and developing countries. In response to generic competition, innovator companies employ a range of life cycle management techniques, including the launch of 'authorised generics'. The generics segment in Australia will see high growth rates in coming years but the prospect for local manufacturing is bleak. The availability of cheap generics in international markets has put pressure on Pharmaceutical Benefits Scheme (PBS) pricing arrangements, and a new policy direction was announced in November 2006. Lower generics prices will have a negative impact on some incumbent suppliers but industrial renewal policies for the medicines industry in Australia are better focused on higher value R&D activities and niche manufacturing of sophisticated products.

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In this paper we consider the significance of cyber 'LAN' cafeacutes as sites where on and off-line practices meet in way that complicates binary notions of the gendered gamer. Existing research into computer games culture suggests a male dominated environment and points to girls' lower levels of competence and participation in games. Building on recent studies interested in the constitution of gender through engagement with online technologies, we draw on Judith Butler's politics of performative resignification, and conceptualise digital culture as a resource through which 'girl' gamers are mobilised and potentially reformulated, experiencing their gaming identities in contradictory ways, and fragmenting the category 'girl' in the very act of articulating their place in a male dominated gaming culture. It is argued that through the meeting of on and off-line practices, LAN cafeacutes operate as a location that is particularly amenable to reformulative work in relation to gendered gaming identities.