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Additional Explanation (additional + explanation)
Selected AbstractsIntravenous Bisphosphonate Therapy Increases Radial Width in Adults With Osteogenesis Imperfecta,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2005Davide Gatti Abstract Neridronate therapy in adult patients with OI significantly increases the cross-sectional area of the proximal radius. This observation may provide an additional explanation for the antifracture efficacy of bisphosphonates. Introduction: Bisphosphonate therapy decreases by 70-90% the fracture risk in patients with osteogenesis imperfecta (OI). This decrease is somewhat greater than that expected from the BMD changes, supporting the hypothesis that bisphosphonate therapy is associated with structural changes, not detectable by BMD measurements. Materials and Methods: To explore this hypothesis, pQCT measurements at the nondominant radius were obtained in a group of adult OI patients participating in a randomized clinical trial with neridronate. Results: The total volumetric BMD of the ultradistal radius rose significantly in patients treated with neridronate and calcium + vitamin D (neridronate group) compared with patients treated with calcium + vitamin D alone (control group). No significant differences were observed in trabecular BMD and in volumetric cortical density in either group. In the neridronate group, the cross-sectional area rose significantly versus both baseline values and the control group. These latter changes were associated with ,20% increases in bending breaking resistance index (BBRI). Conclusion: Our observation, if extended to postmenopausal osteoporosis, may provide a new explanation for the fracture risk reduction observed in osteoporotic patients treated with bisphosphonates. [source] AMP-activated protein kinase enhances the expression of muscle-specific ubiquitin ligases despite its activation of IGF-1/Akt signaling in C2C12 myotubesJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2009Jun F. Tong Abstract Two muscle-specific ubiquitin ligases (UL), muscle atrophy F box (MAFbx) and muscle RING finger 1 (MuRF1), are crucial for myofibrillar protein breakdown. The insulin like growth factor-1 (IGF-1) pathway inhibits muscle UL expression through Akt-mediated inhibition of FoxO transcription factors, while AMP-activated protein kinase (AMPK) promotes UL expression. The underlying cellular mechanism, however, remains obscure. In this study, the effect of AMPK and its interaction with IGF-1 on ubiquitin ligases expression was investigated. C2C12 myotubes were treated with 0, 0.1, 0.3, and 1.0,mM 5-aminoimidazole-4-carboxamide-1-,- D -ribofuranoside (AICAR) in the presence or absence of 50,ng/ml IGF-1. IGF-1 activated Akt, which enhanced phosphorlytion of FoxO3a at Thr 318/321 and reduced the expression of UL. Intriguingly, though activation of AMPK by 0.3 and 1.0,mM AICAR synergized IGF-1-induced Akt activation, the expression of UL was not attenuated, but strengthened by AMPK activation. AICAR treatment decreased FoxO3a phosphorylation at 318/321 in the cytoplasm and induced FoxO3 nuclear relocation. mTOR inhibition increased basal MAFbx expression and reversed the inhibitory effect of IGF-1 on UL expression. In conclusion, our data show that AMPK activation by AICAR stimulates UL expression despite the activation of Akt signaling, which may be due to the possible antagonistic effect of FoxO phosphorylation by AMPK on phosphorylation by Akt. In addition, AMPK inhibition of mTOR may provide an additional explanation for the enhancement of UL expression by AMPK. J. Cell. Biochem. 108: 458,468, 2009. © 2009 Wiley-Liss, Inc. [source] When a Grandiose Self-Image Is Threatened: Narcissism and Self-Concept Clarity as Predictors of Negative Emotions and Aggression Following Ego-ThreatJOURNAL OF PERSONALITY, Issue 4 2002Tanja S. Stucke ABSTRACT Two studies examined the relation between narcissism, self-concept clarity, negative emotions, and aggression based on theoretical assumptions proposed by Baumeister, Smart, and Boden (1996). Narcissism and self-concept clarity were examined as predictors for anger, depression, and verbal aggression following ego-threat, which was operationalized by a bogus performance feedback on an intelligence test. The second study also examined the mediating effects of participants' negative emotions to provide an additional explanation for the aggressive reactions after failure. As expected, narcissism and self-concept clarity were significant predictors of negative emotions and aggression after failure. In accordance with our hypothesis, high narcissists with low self-concept clarity reacted with anger and aggression after failure, whereas less narcissistic individuals with high self-concept clarity showed feelings of depression and no aggression. The results also indicated that aggression was always directed toward the source of the ego-threatening feedback. Additionally, anger and depression could predict the aggressive response after failure but they did not mediate the relation between narcissism, self-concept clarity, performance feedback, and aggression. [source] When does ecosystem engineering cause invasion and species replacement?OIKOS, Issue 8 2008Andrew Gonzalez Introduced exotic species can dominate communities and replace native species that should be better adapted to their local environment, a paradox that is usually explained by the absence of natural enemies and by habitat alteration resulting from anthropogenic disturbance. Additionally, introduced species can enhance their invasion success and impact on native species by modifying selection pressures in their new environment through ecosystem engineering. We analyse a simple dynamic model of indirect competition for habitat between a non-engineering resident species and an engineering exotic species. The conditions for invasion and competitive exclusion of the resident by the exotic species and the range of dynamic outcomes suggested by the model are determined by the form of density dependence. We give simple criteria for the success of the invading species on dimensionless quantities involving rates of ecosystem engineering and of habitat degradation. The model's predictions offer an additional explanation for a range of invasion dynamics reported in the literature, including lag times between introduction and establishment. One intriguing result is that a series of failed invasions may successively reduce environmental resistance to subsequent invasion, through a cumulative effect of habitat transformation. More work is needed to determine the frequency and conditions in which engineering is required for successful establishment, and whether highly-successful (or high-impact) invaders are more likely to possess ecosystem engineering traits. [source] Trade theorems with search unemploymentCANADIAN JOURNAL OF ECONOMICS, Issue 3 2010Yu Sheng Abstract We revisit the Heckscher-Ohlin-Samuelson model in the presence of labour market frictions à la Mortensen-Pissarides. Relaxing the assumption of the one-worker-one-firm matching rule, we show that the Stolper-Samuelson theorem and the Rybczynski theorem may not hold in specific circumstances. We also demonstrate that the Factor Price Equalization theorem is valid only for capital and unemployed labour across countries, but not for employed labour. In equilibrium, trade patterns are determined by countries' factor endowments and relative factor intensities in sectors (independent of factor intensities in production). Finally, our results suggest an additional explanation for the ,missing trade' phenomenon. On ré-examine le modèle de Heckscher-Ohlin-Samuelson quand il y a des frictions à la Mortensen-Pissarides sur le marché du travail. En relaxant la règle d'appariement un-travailleur-une-entreprise, on montre que le théorème de Stolper-Samuelson et celui de Rybczybski peuvent ne pas être valides dans certaines circonstances spécifiques. On montre aussi que le théorème d'égalisation du prix des facteurs est valide seulement pour le capital et le travail non employé entre pays, mais non pour le travail employé. En équilibre, les patterns de commerce sont déterminés par la dotation en facteurs de production des pays et les intensités relatives d'utilisation des facteurs de production entre secteurs (sans rapport avec les intensités de facteurs dans la production). Finalement, les résultats suggèrent une explication additionnelle du phénomène du ,commerce manquant.' [source] Breeding system, branching processes, hybrid swarm theory, and the humped-back diversity relationship as additional explanations for apparent monophyly in the Macaronesian island floraJOURNAL OF ECOLOGY, Issue 4 2005N. ELIZABETH SAUNDERS Summary 1Niche pre-emption and competitive exclusion is unsatisfactory as a sole explanation for the apparent paradox of a large number of monophyletic taxa in the Macaronesian island flora. 2Undetected hybridizations have been proposed as an additional plausible explanation. In addition, hybrid swarm theory predicts that hybridizations between invading species would promote adaptive radiation. 3We suggest that branching processes and coalescence offer yet another plausible explanation allowing for multiple colonizations of closely related taxa, which, because of their later local extinction or hybridization, would lead to apparent monophyly in the molecular record. 4The cause of such widespread radiation of a few taxa has not been explained, but may involve intermediate conditions of disturbance or productivity. This proposition has, to date, only been tested in a microbial model system, but it offers a reasonable explanation for the patterns observed in the Macaronesian flora, and perhaps in other island floras worldwide. [source] National Study of the Relation of Primary Care Shortages to Emergency Department UtilizationACADEMIC EMERGENCY MEDICINE, Issue 3 2007Ilana B. Richman BA Background: Emergency department (ED) visit volumes are increasing nationwide. Objectives: To determine whether states with primary care shortages have higher rates of ED use. Methods: Populations residing in primary care shortage areas were abstracted from the Health Resources and Services Administration Geospatial Database. Annual ED visit volumes were available from the 2001 National ED Inventory. Population data and potential confounders were abstracted from federal data sets. All analyses were conducted at the state level. Results: Primary care shortage densities varied greatly across states, ranging from 3 (New Jersey) to 28 (Mississippi) medically underserved individuals per 100 people. States also varied in their annual ED visit densities, ranging from 23 visits (Hawaii) to 65 visits (Washington, DC) per 100 people. Of the 17 states in the top tertile for primary care shortage, 7 also were in the top tertile for ED visits. Primary care shortage density was positively associated with ED visit density. An increase of 10 medically underserved individuals per 100 people was associated with an annual increase of 4.2 ED visits per 100 people (p = 0.04). The association remained after controlling for six factors, with an increase of 10 medically underserved individuals per 100 people associated with an annual increase of 3.3 ED visits per 100 people (p = 0.04). Nevertheless, five states had high ED visit densities despite comparatively low primary care shortage densities (Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont), whereas five others had low ED visit densities despite high primary care shortage densities (Arizona, Idaho, Montana, New Mexico, and South Dakota). Conclusions: A positive association between primary care shortage densities and ED visit densities was found. Although most states adhere to this pattern, some states do not. Further investigation of this dissociation may yield additional explanations for rising ED visit volumes. [source] | |||||||||||||