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Emerging Hypothesis (emerging + hypothesis)
Selected AbstractsOccupational stress and work-related upper extremity disorders: Concepts and models,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 5 2002Grant D. Huang MPH Abstract Background While research has suggested that interventions targeted at occupational stress (job stress) factors may improve clinical and work outcomes related to work-related musculoskeletal disorders, the emerging hypotheses relating occupational stress to work-related upper extremity disorders (WRUEDs) are not particularly well known among occupational health providers and researchers. Methods Generic job stress and health models and multivariable models of WRUEDs were described and evaluated. Results Models on occupational stress and health/WRUEDs offer unique perspectives on the role of occupational stressors on WRUEDs. However, the limited support for the structure and proposed mechanisms of these models suggest that investigations examining and validating proposed biobehavioral pathways are still needed. Discussion Difficulties in conceptualizing occupational stress have, in the past, hindered its systematic incorporation into occupational health research and prevention/intervention strategies. The present paper provides a common basis for researchers and practitioners with diverse backgrounds to understand job stress and its relation to WRUEDs in order to enhance future efforts. Given the present limitations in the field and the need for comprehensive approaches to WRUEDs, there is great potential for occupational health researchers and clinicians to advance knowledge in this area. Am. J. Ind. Med. 41:298,314, 2002. © 2002 Wiley-Liss, Inc. [source] Nestling sex ratio of golden-winged warblers Vermivora chrysoptera in an introgressed populationJOURNAL OF AVIAN BIOLOGY, Issue 6 2008Kate J. Neville Sex ratio biases in avian species remain controversial, although several studies have documented apparent facultative adjustment of offspring sex ratios. While hybridizing pied and collared flycatchers have exhibited sex ratio skews that may be a response to sex-based costs associated with hybridization, this appears not to be true of a hybridized population of blue-winged Vermivora pinus and golden-winged V. chrysoptera warblers. We examined the primary sex ratio of nestlings in a population of hybrid and introgressed golden-winged warblers. The sex ratio of 298 nestlings from 81 nests in the population was approximately 50:50. We conducted paternity assignments and analyzed groups of nestlings with shared genetic parents ("genetic broods") and found no difference from the expected binomial distribution, and no statistically significant relationship between parental species phenotype and nestling sex ratio. We saw no evidence of preferential production of male or female nestlings, and female hybrids were found to mate and breed in the population. This suggests that heterogametic (female) hybrids are both viable and fertile, and thus that Haldane's Rule does not apply to this system. While populations of hybridizing golden-winged warblers should be monitored for evidence of costs of heterospecific pairings, it is unlikely that adjustment of sex ratios would be the form of compensation for sub-optimal mating conditions. Our results provide support for the emerging hypothesis that hybrids suffer no disadvantage relative to golden-winged and blue-winged warblers. [source] Characterization of HasB, a Serratia marcescens TonB-like protein specifically involved in the haemophore-dependent haem acquisition systemMOLECULAR MICROBIOLOGY, Issue 4 2001Annick Paquelin In Gram-negative bacteria, the TonB,ExbB,ExbD inner membrane multiprotein complex is required for active transport of diverse molecules through the outer membrane. We present evidence that Serratia marcescens, like several other Gram-negative bacteria, has two TonB proteins: the previously characterized TonBSM, and also HasB, a newly identified component of the has operon that encodes a haemophore-dependent haem acquisition system. This system involves a soluble extracellular protein (the HasA haemophore) that acquires free or haemoprotein-bound haem and presents it to a specific outer membrane haemophore receptor (HasR). TonBSM and HasB are significantly similar and can replace each other for haem acquisition. However, TonBSM, but not HasB, mediates iron acquisition from iron sources other than haem and haemoproteins, showing that HasB and TonBSM only display partial redundancy. The reconstitution in Escherichia coli of the S. marcescens Has system demonstrated that haem uptake is dependent on the E. coli ExbB, ExbD and TonB proteins and that HasB is non-functional in E. coli. Nevertheless, a mutation in the HasB transmembrane anchor domain allows it to replace TonBEC for haem acquisition. As the change affects a domain involved in specific TonBEC,ExbBEC interactions, HasB may be unable to interact with ExbBEC, and the HasB mutation may allow this interaction. In E. coli, the HasB mutant protein was functional for haem uptake but could not complement the other TonBEC -dependent functions, such as iron siderophore acquisition, and phage DNA and colicin uptake. Our findings support the emerging hypothesis that TonB homologues are widespread in bacteria, where they may have specific functions in receptor,ligand uptake systems. [source] Probiotics effects on gastrointestinal function: beyond the gut?NEUROGASTROENTEROLOGY & MOTILITY, Issue 5 2009E. F. Verdu Abstract, The digestive tract works through a complex network of integrative functions. At the level of the gut, this integration occurs between the immune, neuromotor and enteroendocrine systems, coordinating the physical and chemical elements of the intestinal barrier in order to facilitate digestion whilst protecting the gut from unwanted components of the luminal contents. Gastrointestinal function is controlled and coordinated by the central nervous system to ensure effective motility, secretion, absorption and mucosal immunity. It follows that perturbations in this complex network could lead to gut dysfunction and symptom generation. Recently, attention has been focused on the emerging hypothesis that gut luminal content contributes to determine normal GI function and on the therapeutic possibilities arising from modulating its impact on gut physiology and immunity using probiotic bacteria. In this issue of Neurogastroenterology and Motility, two papers explore the effect of specific probiotic bacteria on spinal neuronal activation and in vitro muscle contractility. These papers support the notion that the composition of the intestinal microbiota can influence gut neuro-motor function and enhance our understanding on the mechanisms of action underlying the effects of specific probiotics on gut functional disorders. [source] A new amyloid , variant favoring oligomerization in Alzheimer's-type dementiaANNALS OF NEUROLOGY, Issue 3 2008Takami Tomiyama PhD Objective Soluble oligomers of amyloid , (A,), rather than amyloid fibrils, have been proposed to initiate synaptic and cognitive dysfunction in Alzheimer's disease (AD). However, there is no direct evidence in humans that this mechanism can cause AD. Here, we report a novel amyloid precursor protein (APP) mutation that may provide evidence to address this question. Methods A Japanese pedigree showing Alzheimer's-type dementia was examined for mutations in APP, PSEN1, and PSEN2. In addition, 5,310 Japanese people, including 2,121 patients with AD, were screened for the novel APP mutation. The pathogenic effects of this mutation on A, production, degradation, aggregation, and synaptotoxicity were also investigated. Results We identified a novel APP mutation (E693,) producing variant A, lacking gulutamate-22 (E22,) in Japanese pedigrees showing Alzheimer's-type dementia and AD. Although the secretion of total A, was markedly reduced by this mutation, the variant A, was more resistant to proteolytic degradation. The mutant peptides showed the unique aggregation property of enhanced oligomerization but no fibrillization, and inhibited hippocampal long-term potentiation more potently than wild-type peptide in rats in vivo. Consistent with the nonfibrillogenic property of the variant A,, a very low amyloid signal was observed in the patient's brain on positron emission tomography using Pittsburgh compound-B. Interpretation The E693, mutation has been suggested as a cause of dementia because of enhanced formation of synaptotoxic A, oligomers. Our findings may provide genetic validation in humans for the emerging hypothesis that the synaptic and cognitive impairment in AD is primarily caused by soluble A, oligomers. Ann Neurol 2008 [source] | |||||||||||||