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Possible Underlying Mechanisms (possible + underlying_mechanism)
Selected AbstractsShift of attention in depth in a semi-realistic settingJAPANESE PSYCHOLOGICAL RESEARCH, Issue 3 2002Toshiaki Miura Abstract: This research was based on previous research on the useful field of view in real driving, however shift of attention was examined in depth by the use of an improved tunnel simulator. Despite of the importance of this area of research, nothing like this has been performed previously. The subjects' task was judgment of the relative distance of targets (farther, nearer, or the same), in comparison with a fixation point. Reaction times were measured. There were two variables. One was three observing conditions. Subjects moved at apparent speeds of 40 km/h or 80 km/h or were stationary. The second variable was the validity of the precue concerning the location of the appearance of the target relative to the fixation point. There were three conditions, valid, invalid and or neutral. The results clearly showed that reaction times for nearer targets were shorter than those for farther targets in all conditions. This supports a viewer-centered representation of three-dimensional space. Concerning the direction of shift of attention, reaction time for shift of attention from far locations to near locations was shorter than for the opposite. This difference was more remarkable in the moving condition than in the stationary condition. This was called the rubber band metaphor of attention in locomotion (asymmetrical viewer-centered mode of shift of attention in depth). These results are ecologically valid. Possible underlying mechanisms are discussed from the viewpoint of distribution of attention resource. [source] Combined R-,,lipoic acid and acetyl-L-carnitine exerts efficient preventative effects in a cellular model of Parkinson's diseaseJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 1-2 2010Hongyu Zhang Abstract Mitochondrial dysfunction and oxidative damage are highly involved in the pathogenesis of Parkinson's disease (PD). Some mitochondrial antioxidants/nutrients that can improve mitochondrial function and/or attenuate oxidative damage have been implicated in PD therapy. However, few studies have evaluated the preventative effects of a combination of mitochondrial antioxidants/nutrients against PD, and even fewer have sought to optimize the doses of the combined agents. The present study examined the preventative effects of two mitochondrial antioxidant/nutrients, R-,,lipoic acid (LA) and acetyl-L-carnitine (ALC), in a chronic rotenone-induced cellular model of PD. We demonstrated that 4-week pretreatment with LA and/or ALC effectively protected SK-N-MC human neuroblastoma cells against rotenone-induced mitochondrial dysfunction, oxidative damage and accumulation of ,-synuclein and ubiquitin. Most notably, we found that when combined, LA and ALC worked at 100,1000-fold lower concentrations than they did individually. We also found that pretreatment with combined LA and ALC increased mitochondrial biogenesis and decreased production of reactive oxygen species through the up-regulation of the peroxisome proliferator-activated receptor-, coactivator 1, as a possible underlying mechanism. This study provides important evidence that combining mitochondrial antioxidant/nutrients at optimal doses might be an effective and safe prevention strategy for PD. [source] Sonographic evaluation of gallbladder volume and ejection fraction in obese women without gallstonesJOURNAL OF CLINICAL ULTRASOUND, Issue 7 2003Ramazan Sari MD Abstract Purpose Obese people have an increased incidence of gallstones. Although the exact pathogenic mechanisms of gallstone development are unknown, impaired gallbladder emptying has been suggested as a possible underlying mechanism. Our aim was to investigate this possibility by evaluating gallbladder motility and related factors in obese and nonobese women without gallstones. Methods This study included 79 obese women and 25 nonobese healthy women. Using real-time sonography, we evaluated fasting and postprandial (15th-, 30th-, 45th-, 60th-, 75th-, 90th-, 120th-, and 150th-minute) gallbladder volumes and ejection fractions. The smallest postprandial volume was considered the residual volume. Results Mean (± standard deviation) fasting and residual gallbladder volumes were 43.2 ± 18.3 cm3 and 21.4 ± 11.2 cm3, respectively, in the obese women and 28.1 ± 12.3 cm3 and 7.9 ± 3.4 cm3, respectively, in the nonobese women. Maximal ejection fraction was 49 ± 19% in obese women and 63 ± 29% in nonobese women (p = 0.001). The fasting and residual volumes and the postprandial volumes at all time points were higher in obese women than in nonobese women (p < 0.001). In addition, 15th-, 30th-, 45th-, 60th-, 75th-, and 90th-minute postprandial ejection fractions were lower in obese women than in nonobese women (p < 0.001). Positive correlations were found between fasting gallbladder volume and body mass index and body fat weight and between residual volume and body mass index, waist circumference, body fat percentage, and body fat weight (p < 0.05 for all comparisons). Conclusions Our results show that fasting and postprandial gallbladder volumes are higher and that postprandial gallbladder motility is lower in obese than in nonobese women. There are positive correlations between fasting gallbladder volume and body weight, body mass index, and body fat weight. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31: 352,357, 2003 [source] A method to prevent cross contamination during 2-DE by ,-amyloid peptidesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 19 2010Heinke Schieb Abstract A method for the efficient decontamination of aluminium oxide ceramic 2-DE focusing trays from ,-amyloid peptides (A,) is reported. As these contaminations were resistant to the standard cleaning procedures, additional harsh cleaning steps were necessary for their efficient removal. Our observations suggest that specific surface properties affect the degree of adsorption of the A,-peptides. "Surface catalysed amyloid aggregation" in the aluminium oxide ceramic trays is proposed as a possible underlying mechanism for the occurrence of proteinase K-resistant forms of A,. [source] Duplication, divergence and formation of novel protein topologiesBIOESSAYS, Issue 10 2006Christine Vogel The rearrangement or permutation of protein substructures is an important mode of divergence. Recent work1 explored one possible underlying mechanism called permutation-by-duplication, which produces special forms of motif rearrangements called circular permutations. Permutation-by-duplication, involving gene duplication, fusion and truncation, can produce fully functional intermediate proteins1 and thus represents a feasible mechanism of protein evolution. In spite of this, circular permutations are relatively rare and we discuss possible reasons for their existence. BioEssays 28: 973,978, 2006. © 2006 Wiley Periodicals, Inc. [source] Skeletal muscle fibre diversity and the underlying mechanismsACTA PHYSIOLOGICA, Issue 4 2010M. Canepari Abstract The review first briefly summarizes how myosin isoforms have been identified as the major determinant of the functional variability among skeletal muscle fibres. The latter feature is a major characteristic of muscle fibres and a major basis of skeletal muscle heterogeneity and plasticity in vivo. Then, evidence is reported, which indicates that the properties of muscle fibres can vary with no change in the myosin isoform they express. Moreover, the physiological and pathological conditions (ageing, disuse, exercise training, muscular dystrophy) in which such myosin isoform independent change in functional properties occurs and the possible underlying mechanisms are considered. Finally, the known molecular bases of the functional differences among slow and fast isoforms are briefly dealt with. [source] Cardiac basal metabolism: energetic cost of calcium withdrawal in the adult rat heartACTA PHYSIOLOGICA, Issue 3 2010P. Bonazzola Abstract Aim:, Cardiac basal metabolism upon extracellular calcium removal and its relationship with intracellular sodium and calcium homeostasis was evaluated. Methods:, A mechano-calorimetric technique was used that allowed the simultaneous and continuous measurement of both heat rate and resting pressure in arterially perfused quiescent adult rat hearts. Using pharmacological tools, the possible underlying mechanisms related to sodium and calcium movements were investigated. Results:, Resting heat rate (expressed in mW g,1dry wt) increased upon calcium withdrawal (+4.4 ± 0.2). This response was: (1) unaffected by the presence of tetrodotoxin (+4.3 ± 0.6), (2) fully blocked by both, the decrease in extracellular sodium concentration and the increase in extracellular magnesium concentration, (3) partially blocked by the presence of either nifedipine (+2.8 ± 0.4), KB-R7943 (KBR; +2.5 ± 0.2), clonazepam (CLO; +3.1 ± 0.3) or EGTA (+1.9 ± 0.3). The steady heat rate under Ca2+ -free conditions was partially reduced by the addition of Ru360 (,1.1 ± 0.2) but not CLO in the presence of EGTA, KBR or Ru360. Conclusion:, Energy expenditure for resting state maintenance upon calcium withdrawal depends on the intracellular rise in both sodium and calcium. Our data are consistent with a mitochondrial Ca2+ cycling, not detectable under normal calcium diastolic levels. The experimental condition here analysed, partially simulates findings reported under certain pathological situations including heart failure in which mildly increased levels of both diastolic sodium and calcium have also been found. Therefore, under such pathological conditions, hearts should distract chemical energy to fuel processes associated with sodium and calcium handling, making more expensive the maintenance of their functions. [source] Gait characteristics of diabetic patients: a systematic reviewDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 3 2008L. Allet Abstract Patients with diabetes are at higher risk of experiencing fall-related injuries when walking than healthy controls. The underlying mechanism responsible for this is not yet clear. Thus we intend to summarize diabetic patients' gait characteristics and emphasize those which could be the possible underlying mechanisms for increased fall risk. This systematic review aims, in particular, to: (1) evaluate the quality of existing studies which investigate the gait characteristics of diabetic patients, (2) highlight areas of agreement and contradiction in study results, (3) discuss and emphasize parameters associated with fall risk, and (4) propose new orientations and further domains for research needed for their fall risk prevention. We conducted an electronic search of Pedro, PubMed, Ovid and Cochrane. Two authors independently assessed all abstracts. Quality of the selected articles was scored, and the study results summarized and discussed. We considered 236 abstracts of which 28 entered our full text review. Agreement on data quality between two reviewers was high (kappa: 0.90). Authors investigating gait parameters in a diabetic population evaluated in particular parameters either associated with fall risk (speed, step length or step-time variability) or with ulcers (pressure). There is agreement that diabetic patients walk slower, with greater step variability, and present higher plantar pressure than healthy controls. We concluded that diabetic patients present gait abnormalities, some of which can lead to heightened fall risk. To understand its' underlying mechanisms, and to promote efficient prevention, further studies should analyse gait under ,real-life' conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source] KAI1 gene suppresses invasion and metastasis of hepatocellular carcinoma MHCC97-H cells in vitro and in animal modelsLIVER INTERNATIONAL, Issue 1 2008Jian-min Yang Abstract Background: Downregulation of KAI1 gene expression has been found in many types of cancer cells and is closely related to cancer invasion and metastasis. This study was aimed at investigating the effects and possible underlying mechanisms of KAI1 gene on invasion and metastasis of human hepatocellular carcinoma (HCC). Methods: The invasive ability, visco-elastic properties and cell adhesion forces were analysed in different HCC cells originating from the MHCC97-H cell line transfected with either the sense or the antisense KAI1 expression plasmid. Tumuorigenicity, metastatic abilities, extracellular matrix (ECM) and intercellular adhesion molecule-1 (ICAM-1) expression were also evaluated in the nude mouse models of the xenografted and orthotopic liver cancer cells. Results: Compared with their parental cells, in the HCC cells transfected with the sense KAI1 gene, the invasive ability in vitro was significantly decreased (P<0.01); the cellular elastic coefficients K1, K2 and , were significantly higher (P<0.05); the cells adhesion forces to fibronectin were significantly lower (P<0.01). The sense KAI1 gene transfection into the cancer cells also inhibited their invasion and lung metastasis in the orthotopic liver cancer nude mice. However, the opposite changes were observed in the HCC cells transfected with the antisense KAI1 gene. KAI1 gene transfection also affected ECM and ICAM-1 expression in the transplanted liver cancer. Conclusion: The KAI1 gene plays an important role in the invasion and metastasis of human HCC and its upregulation in HCC cells suppresses their invasive and metastatic abilities. KAI1 gene functioned as a metastasis inhibitor by regulating the HCC cell biophysical behaviours including aggregation, adhesion, motility and visco-elastic properties. [source] Interleukin-1 gene cluster variants with innate cytokine production profiles and osteoarthritis in subjects from the Genetics, Osteoarthritis and Progression StudyARTHRITIS & RHEUMATISM, Issue 4 2010Ingrid Meulenbelt Objective To assess whether genetic variation in the interleukin-1 (IL-1) gene cluster contributes to familial osteoarthritis (OA) by influencing innate ex vivo production of IL-1, or IL-1 receptor antagonist (IL-1Ra). Methods Innate ex vivo IL-1, and IL-1Ra production upon lipopolysaccharide (LPS) stimulation of whole blood cells was measured in subjects from the Genetics, Osteoarthritis and Progression (GARP) Study, which includes sibling pairs in which at least one sibling has symptomatic OA at multiple sites. Radiographic OA (ROA) was assessed by Kellgren/Lawrence score. Subjects from the GARP Study and controls from the Rotterdam Study were genotyped for 7 single-nucleotide polymorphisms (SNPs) encompassing the IL-1 gene cluster on chromosome 2q13. Linkage disequilibrium analysis and genotype and haplotype association analysis were performed to assess the relationship between the IL-1 gene cluster SNPs, innate ex vivo cytokine production, and OA. Results Among subjects in the GARP Study, the haplotype variable-number tandem repeat in intron 2/T+8006C/T+11100C 2/2/1 of the IL1RN gene was significantly associated with reduced innate ex vivo bioavailability of IL-1, upon LPS stimulation (P = 0.026) and with ROA at the highest number of joint locations. Conclusion These results show that genetic variation at the IL-1 gene cluster is associated with lower IL-1, bioavailability and with OA at a large number of joint locations. The data further indicate that, among subjects with OA affecting the highest number of joints, the innate immune system may be activated, thereby obscuring possible underlying mechanisms. [source] The skeletal manifestations of the congenital disorders of glycosylationCLINICAL GENETICS, Issue 6 2008D Coman The congenital disorders of glycosylation (CDG) are a rapidly expanding disease group with protean presentations. Specific end-organ involvement leads to significant morbidity and mortality, and the skeletal manifestations are often not appreciated, apart from the common association of osteopaenia with CDG-Ia. We performed a literature review of all documented skeletal manifestations in reported CDG patients, revealing a diverse range of skeletal phenotypes. We discuss the possible underlying mechanisms of these skeletal manifestations observed in CDG that are important and frequently under-recognized. [source] | |||||||||||||