Lene Hansen

Glucagon-Like Peptide-1-(7–36)Amide Is Transformed to Glucagon-Like Peptide-1-(9–36)Amide by Dipeptidyl Peptidase IV in the Capillaries Supplying the L Cells of the Porcine Intestine

The insulinotropic hormone glucagon-like peptide-1 (GLP-1) is stored in the intestinal L cell in an active form, GLP-1-(7–36)amide, but more than half of the endogenous peptide circulates in an inactive, N-terminally truncated form, GLP-1-(9–36)amide. This study examined the GLP-1 newly secreted from the porcine ileum, in vitro (isolated perfused preparation) and in vivo (anesthetized pig), to determine where this conversion occurs. Although the GLP-1 extractable from the porcine ileum is predominantly the intact peptide (94.6 ± 1.7%), a large proportion of the GLP-1 that is secreted has already been degraded to the truncated form both in vitro (53.8± 0.9% intact) and in vivo (32.9 ± 10.8% intact). In the presence of a specific dipeptidyl peptidase IV (DPP IV) inhibitor (valine-pyrrolidide), the proportion of intact GLP-1 released from the perfused ileum was increased under both basal (99% intact; P < 0.05) and stimulated (86–101% intact; P < 0.05) conditions. Immunohistochemical and histochemical studies...

Theorizing the image for Security Studies Visual securitization and the Muhammad Cartoon Crisis

This article provides a framework for the study of visual securitization, that is, when images constitute something or someone as threatened and in need of immediate defense or when securitizing actors argue that images ‘speak security’. To study security politics is to focus on the public constitution of threats and dangers; to study visual securitization, therefore, requires an analysis not just of the image as a free-standing entity, but of the ways it is constituted through spoken and written discourse. To analyze the process of visual securitization, this article advances an inter-visual/intertextual model consisting of four components: the visual itself, its immediate intertextual context, the wider policy discourse, and the constitutions of the image. Three additional sets of theoretical arguments deepen this model by pointing to the specificity of the image as comprised through immediacy, circulability, and ambiguity, the strategies of depiction that images employ, and the genres through which images are brought to the audience. The applicability of the theoretical framework is illustrated through a case study of one of the most conspicuous cases of visual securitization: the Muhammad Cartoon Crisis.

The end of International Relations theory

With a view to providing contextual background for the Special Issue, this opening article analyses several dimensions of ‘The end of International Relations theory?’ It opens with a consideration of the status of different types of theory. Thereafter, we look at the proliferation of theories that has taken place since the emergence of the third/fourth debate. The coexistence and competition between an ever-greater number of theories begs the question: what kind of theoretical pluralism should IR scholars embrace? We offer a particular account of theoretical engagement that is preferable to the alternatives currently being practised: integrative pluralism. The article ends on a cautiously optimistic note: given the disciplinary competition that now exists in relation to explaining and understanding global social forces, International Relations may find resilience because it has become theory-led, theory-literate and theory-concerned.

Glucagon-like peptide-1 secretion is influenced by perfusate glucose concentration and by a feedback mechanism involving somatostatin in isolated perfused porcine ileum

Glucagon-like peptide-1 (GLP-1) is released from intestinal L-cells in response to ingestion of meals. The mechanisms regulating its secretion are not clear, but local somatostatin (SS) restrains GLP-1 secretion. We investigated feedback and substrate regulation of GLP-1 and SS secretion, using isolated perfused porcine ileum (n=17). Effluents were measured for GLP-1 and SS. Perfusion pressure and motility were recorded. Investigated parameters included spontaneous fluctuations, changes in perfusate glucose concentrations (3.5, 5, 11 mM) and addition of insulin (1 nM). We also investigated the effect of proglucagon products, glucagon (10 nM), GLP-1 and GLP-2 (0.1, 1, and 10 nM) on GLP-1 and SS secretion, as well as on glucagon-like peptide-2 (GLP-2), peptide YY (PYY) and GIP secretion, all possible product of L-cells or neighbour cells. Perfusate glucose concentration dose-dependently stimulated GLP-1 secretion (p=0.011). Insulin had no effect. Glucagon weakly stimulated GIP secretion. GLP-1 stimulated SS secretion and motor activity, but inhibited GLP-2, GIP and PYY secretion and perfusion pressure. GLP-2 weakly stimulated SS secretion. We conclude (a) that GLP-1 secretion is influenced by perfusate glucose concentration and (b) that L-cell secretion is feedback regulated by GLP-1 itself, probably via paracrine SS activity.

Reconstructing desecuritisation: the normative-political in the Copenhagen School and directions for how to apply it

The concept of desecuritisation – the move of an issue out of the sphere of security – has been the subject of heated international political theory debate and adopted in case studies across a range of sectors and settings. What unites the political theory and the applied literature is a concern with the normative-political potential of desecuritisation. This article documents the political status and content of desecuritisation through four readings: one which shows how desecuritisation is a Derridarian supplement to the political concept of securitisation; one which traces the understanding of the public spheres ability to rework the friend-enemy distinction; one which emphasises the role of choice, responsibility, and decisions; and one which uncovers the significance of the historical context of Cold War detente. The last part of the article provides a reading of the varied use of desecuritisation in applied analysis and shows how these can be seen as falling into four forms of desecuritisation. Each of the latter identifies a distinct ontological position as well as a set of more specific political and normative questions.

The effects of duodenal peptides on glucagon-like peptide-1 secretion from the ileum. A duodeno--ileal loop?

Secretion of the gut hormone glucagon-like peptide-1 (GLP-1) is stimulated by meal ingestion. The response is rapid, suggesting a stimulatory pathway elicited from the upper gastrointestinal area. In pigs, we have been unable to demonstrate a neural stimulatory pathway, but GLP-1 secretion is regulated by local somatostatin secretion. In search for an endocrine pathway, we studied the effect of a range of concentrations of cholecystokinin octapeptide (26-33) (CCK 8), gastric inhibitory peptide 1-42 (GIP), secretin, motilin, calcitonin gene-related peptide (CGRP), and the modified amino acid, 5-hydroxytryptamine (serotonin, 5-HT) on GLP-1 and somatostatin release from isolated perfused segments of porcine ileum.GLP-1 secretion was stimulated by 1 nM CCK 8 and 10 nM GIP, but suppressed by 1 nM motilin and 1 microM 5-HT. Secretin and CGRP had no effect. Somatostatin secretion was stimulated by CCK 8 at 1 and 10 nM, by GIP at 1 and 10 nM and by 10 nM CGRP. Secretin, 5-HT and motilin had no effect on somatostatin secretion. We conclude that CCK 8 and GIP 1-42 stimulated GLP-1 secretion, but only in concentrations greatly exceeding normal postprandial concentrations. Thus, we find it unlikely that endocrine agents from the duodenum regulate GLP-1 secretion in pigs.

How images make world politics: International icons and the case of Abu Ghraib

This article introduces international icons to the field of International Relations. International icons are freestanding images that are widely circulated, recognised, and emotionally responded to. International icons come in the form of foreign policy icons familiar to a specific domestic audience, regional icons, and global icons. Icons do not speak foreign policy in and of themselves rather their meaning is constituted in discourse. Images rise to the status of international icons in part through images that appropriate the icon itself, either in full or through inserting parts of the icon into new images. Appropriations might be used and read as critical interventions into foreign policy debates, but such readings should themselves be subjected to analysis. A three-tier analytical and methodological framework for studying international icons is presented and applied in a case study of the hooded prisoner widely claimed to be emblematic of the Abu Ghraib prison scandal.

The politics of securitization and the Muhammad cartoon crisis: A post-structuralist perspective

A broad array of authors and schools have influenced Barry Buzan and Ole Wæver’s formulation of securitization theory, including John L. Austin, Jacques Derrida and Carl Schmitt. This article draws attention to and strengthens the post-structuralist elements in the writings of Buzan and Wæver, as this part of the theory has received less attention than those attributable to Schmitt and Austin. Starting from securitization theory as developed by Buzan and Wæver and engaging with later expansions of the theory, I suggest a post-structuralist framework built around three questions: Through which discursive structures are cases and phenomena represented and incorporated into a larger discursive field? What is the epistemic terrain through which phenomena are known? And, what are the substantial modalities that define what kind of an issue a security problem is? The last part of the article brings this framework to bear on the ‘Muhammad cartoon crisis’ that began with the publication of 12 cartoons depicting the Prophet Muhammad in the Danish newspaper Jyllands-Posten in 2005.

Metabolism of glucagon-like peptide-2 in pigs: Role of dipeptidyl peptidase IV

Little is known about the metabolism of the intestinotropic factor glucagon-like peptide-2 (GLP-2); except that it is a substrate for dipeptidyl peptidase IV (DPP-IV) and that it appears to be eliminated by the kidneys. We, therefore, investigated GLP-2 metabolism in six multicatheterized pigs receiving intravenous GLP-2 infusions (2 pmol/kg/min) before and after administration of valine-pyrrolidide (300 mumol/kg; a well characterized DPP-IV inhibitor). Plasma samples were analyzed by radioimmunoassays allowing determination of intact, biologically active GLP-2 and the DPP-IV metabolite GLP-2 (3-33). During infusion of GLP-2 alone, 30.9+/-1.7% of the infused peptide was degraded to GLP-2 (3-33). After valine-pyrrolidide, there was no significant formation of the metabolite. Significant extraction of intact GLP-2 was observed across the kidneys, the extremities (represented by a leg), and the splanchnic bed, resulting in a metabolic clearance rate (MCR) of 6.80+/-0.47 ml/kg/min and a plasma half-life of 6.8+/-0.8 min. Hepatic extraction was not detected. Valine-pyrrolidide addition did not affect extraction ratios significantly, but decreased (p=0.003) MCR to 4.18+/-0.27 ml/kg/min and increased (p=0.052) plasma half-life to 9.9+/-0.8 min. The metabolite was eliminated with a half-life of 22.1+/-2.6 min and a clearance of 2.07+/-0.11 ml/kg/min. In conclusion, intact GLP-2 is eliminated in the peripheral tissues, the splanchnic bed and the kidneys, but not in the liver, by mechanisms unrelated to DPP-IV. However, DPP-IV is involved in the overall GLP-2 metabolism and seems to be the sole enzyme responsible for N-terminal degradation of GLP-2.

A Case for Seduction? Evaluating the Poststructuralist Conceptualization of Security

This paper argues that the field of security studies would benefit from engaging more closely with the poststructuralist writings on security than has previously been the case. Poststructuralism advocates a position different from both the traditional realist and idealist perspectives in IR and offers important insights on the construction of the national-international dichotomy, the relationship between national identity and security politics, the discursive character of the concept of security, and the late-modern transformation of security. Specifically, poststructuralism is an important contribution to the debate on whether and/or how to expand the concept of security. It is argued from the poststructuralist position, most clearly by Ole Wæver, that security is a discursive practice and that the concept of security cannot therefore by definition be linked to the military domain: the crucial point is not to establish an objective relationship between the concept and the possible domains of security, but to study whether and how an issue is securitized. The paper concludes by pointing towards further research within poststructuralist security studies and argues in favour of more studies problematizing the possible and argues relationships between the state and the Other, asking whether security politics has to be built on a conquest of the Other.