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Little Correlation (little + correlation)
Selected AbstractsREVIEW: Understanding the construct of impulsivity and its relationship to alcohol use disordersADDICTION BIOLOGY, Issue 2 2010Danielle M. Dick ABSTRACT There are well-established links between impulsivity and alcohol use in humans and other model organisms; however, the etiological nature of these associations remains unclear. This is likely due, in part, to the heterogeneous nature of the construct of impulsivity. Many different measures of impulsivity have been employed in human studies, using both questionnaire and laboratory-based tasks. Animal studies also use multiple tasks to assess the construct of impulsivity. In both human and animal studies, different measures of impulsivity often show little correlation and are differentially related to outcome, suggesting that the impulsivity construct may actually consist of a number of more homogeneous (and potentially more meaningful) subfacets. Here, we provide an overview of the different measures of impulsivity used across human and animal studies, evidence that the construct of impulsivity may be better studied in the context of more meaningful subfacets, and recommendations for how research in this direction may provide for better consilience between human and animal studies of the connection between impulsivity and alcohol use. [source] Variable Temperature Mobility Analysis of n-Channel, p-Channel, and Ambipolar Organic Field-Effect TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Joseph A. Letizia Abstract The temperature dependence of field-effect transistor (FET) mobility is analyzed for a series of n-channel, p-channel, and ambipolar organic semiconductor-based FETs selected for varied semiconductor structural and device characteristics. The materials (and dominant carrier type) studied are 5,5,,,-bis(perfluorophenacyl)-2,2,:5,,2,:5,,2,,,-quaterthiophene (1, n-channel), 5,5,,,-bis(perfluorohexyl carbonyl)-2,2,:5,,2,:5,,2,,,-quaterthiophene (2, n-channel), pentacene (3, p-channel); 5,5,,,-bis(hexylcarbonyl)-2,2,:5,,2,:5,,2,,,-quaterthiophene (4, ambipolar), 5,5,,,-bis-(phenacyl)-2,2,: 5,,2,:5,,2,,,-quaterthiophene (5, p-channel), 2,7-bis((5-perfluorophenacyl)thiophen-2-yl)-9,10-phenanthrenequinone (6, n-channel), and poly(N -(2-octyldodecyl)-2,2,-bithiophene-3,3,-dicarboximide) (7, n-channel). Fits of the effective field-effect mobility (µeff) data assuming a discrete trap energy within a multiple trapping and release (MTR) model reveal low activation energies (EAs) for high-mobility semiconductors 1,3 of 21, 22, and 30,meV, respectively. Higher EA values of 40,70,meV are exhibited by 4,7 -derived FETs having lower mobilities (µeff). Analysis of these data reveals little correlation between the conduction state energy level and EA, while there is an inverse relationship between EA and µeff. The first variable-temperature study of an ambipolar organic FET reveals that although n-channel behavior exhibits EA,=,27,meV, the p-channel regime exhibits significantly more trapping with EA,=,250,meV. Interestingly, calculated free carrier mobilities (µ0) are in the range of ,0.2,0.8,cm2,V,1 s,1 in this materials set, largely independent of µeff. This indicates that in the absence of charge traps, the inherent magnitude of carrier mobility is comparable for each of these materials. Finally, the effect of temperature on threshold voltage (VT) reveals two distinct trapping regimes, with the change in trapped charge exhibiting a striking correlation with room temperature µeff. The observation that EA is independent of conduction state energy, and that changes in trapped charge with temperature correlate with room temperature µeff, support the applicability of trap-limited mobility models such as a MTR mechanism to this materials set. [source] Screening for target Rabs of TBC (Tre-2/Bub2/Cdc16) domain-containing proteins based on their Rab-binding activityGENES TO CELLS, Issue 9 2006Takashi Itoh It has recently been proposed that the TBC (Tre2/Bub2/Cdc16) domain functions as a GAP (GTPase-activating protein) domain for small GTPase Rab. Because of the large number of Rab proteins in mammals, however, most TBC domains have never been investigated for Rab-GAP activity. In this study we established panels of the GTP-fixed form of 60 different Rabs constructed in pGAD-C1, a yeast two-hybrid bait vector. We also constructed a yeast two-hybrid prey vector (pGBDU-C1) that harbors the cDNA of 40 distinct TBC proteins. Systematic investigation of 2400 combinations of 60 GTP-fixed Rabs and 40 TBC proteins by yeast two-hybrid screening revealed that seven TBC proteins specifically and differentially interact with specific Rabs (e.g. OATL1 interacts with Rab2A; FLJ12085 with Rab5A/B/C; and Evi5-like with Rab10). Measurement of in vitro Rab-GAP activity revealed that OATL1 and Evi5-like actually possess significant Rab2A- and Rab10-GAP activity, respectively, but that FLJ12085 do not display Rab5A-GAP activity at all. These results indicate that specific interaction between TBC protein and Rab would be a useful indicator for screening for the target Rabs of some TBC/Rab-GAP domains, but that there is little correlation between the Rab-binding activity and Rab-GAP activity of other TBC proteins. [source] Health care funding levels and patient outcomes: a national studyHEALTH ECONOMICS, Issue 4 2007Margaret M. Byrne Abstract Background: Health care funding levels differ significantly across geographic regions, but there is little correlation between regional funding levels and outcomes of elderly Medicare beneficiaries. Our goal was to determine whether this relationship holds true in a non-Medicare population cared for in a large integrated health care system with a capitated budget allocation system. Methods: We explored the association between health care funding and risk-adjusted mortality in the 22 Veterans Affairs (VA) geographic Networks over a six-year time period. Allocations to Networks were adjusted for illness burden using Diagnostic Cost Groups. To test the association between funding and risk-adjusted three-year mortality, we ran logistic regressions with single-year patient cohorts, as well as hierarchical regressions on a six year longitudinal data set, clustering on VA Network. Results: A $1000 increase in funding per unit of patient illness burden was associated with a 2,8% reduction in three-year mortality in cross sectional regressions. However, in longitudinal hierarchical regressions clustering on Network, the significant effect of funding level was eliminated. Conclusions: When longitudinal data are used, the significant cross sectional effect of funding levels on mortality disappear. Thus, the factors driving differences in mortality are Network effects, although part of the Network effect may be due to past levels of funding. Our results provide a caution for cross sectional examinations of the association between regional health care funding levels and health outcomes. Copyright © 2006 John Wiley & Sons, Ltd. [source] Should TPMT genotype and activity be used to monitor 6-mercaptopurine treatment in children with acute lymphoblastic leukaemia?JOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 6 2007M. Fakhoury PharmD PhD Summary Background and objective: The activity of thiopurine S -methyltransferase (TPMT), a key enzyme in the metabolism of purine analogues, displays wide inter-subject variability partly due to a genetic polymorphism. Previous studies have suggested adjusting purine analogues dosing according to TPMT activity but measurements are costly and time-consuming. It is still unclear, especially under treatment, whether the simpler TPMT genotyping reliably predicts enzyme activity. Our aim was to study the possible correlation of TPMT genotype with phenotype. Methods: We determined the genotypic status and TMPT activity, at diagnosis and after 6 months of maintenance therapy, of 118 children with acute lymphoblastic leukaemia (ALL). Results and Discussion: Eighty-nine per cent of the children had a homozygous wild-type genotype (group 1), 11% had one or two mutant allele(s) (group 2). At both time points, TPMT activity (U/mL peripheral red blood cell) was significantly higher in group 1 than in group 2 (P < 0·001) but inter-group levels overlapped considerably. There was considerable heterogeneity in the percentage increase in TPMT activity after therapy, and little correlation between metabolites ratio [6-methylmercaptopurine derivative/6-thioguanine nucleotides (6-TGN)] and TPMT activity at the end of 6 months' maintenance treatment. These results show that TPMT activity cannot be used as an accurate tool for 6-mercaptopurine monitoring. Conclusion: Genotyping at diagnosis identifies patients with a homozygous mutant TPMT and may prevent severe and life-threatening toxicity. ALL treatment monitoring should preferentially be based on repeated determinations of intracellular active metabolites (6-TGN) and methylated metabolites. [source] G1 cyclins in oral epithelial dysplasiaJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 2 2001R. J. Oliver Abstract: The G1 cyclins, D1, D3 and E, were investigated in 38 lesions of oral epithelial dysplasia from the floor of the mouth or the lateral border of the tongue. Their immunohistochemical expression was observed and compared with that of Ki-67 and with the degree of dysplasia assessed by the semi-objective technique of Smith & Pindborg. Antibody labelled cells were quantified and expressed as a percentage (LI%) of the total nucleated cell population and per mm basement membrane length (LI/mm). The labelling indices of all of the antibodies were high and quantitatively similar. There were no significant correlations with the degree of dysplasia assessed by the atypia scores. There was a correlation between labelling indices for the various antibodies expressed as LI/mm but little correlation between the indices expressed as LI%. The distribution of the D cyclins was similar to that of Ki-67 with relatively few of the basal cells demonstrating immunoreactivity. The reasons for this are discussed in the paper. Some cross-reactivity was observed with the cyclin antibodies. We conclude that the antibodies against the cyclins used in the present study are not a useful adjunct in the study of the cell kinetics of oral epithelial dysplasia. [source] Activation of cyclin-dependent kinases CDC2 and CDK2 in hepatocellular carcinomaLIVER INTERNATIONAL, Issue 3 2002Kay K. W. Li Abstract: Background: The cyclin-dependent kinases (CDKs) CDC2 and CDK2 are key regulators of the cell cycle. The expression of the CDK alone does not necessary reflect their true activities because they are highly regulated by post-translational mechanisms. Human hepatocellular carcinoma (HCC) is one of the most common cancers in the world, but the kinase activities of CDKs in HCC have not been examined. Methods: Here we examined the protein expression and kinase activities associated with CDC2 and CDK2 in HCC and the corresponding non-tumorous liver tissues. Results: CDC2 and CDK2 are activated in HCC in over 70% and 80% of the cases, respectively, but have little correlation with clinical parameters and PCNA expression. Interestingly, PCNA was readily detectable in extracts from non-tumorous liver, but more than 60% of samples contain higher concentration of PCNA in HCC than the corresponding non-tumorous tissues. CDC2 and CDK2 are generally activated in the same HCC samples, but the extent of their activation varied significantly, suggesting that the pathways leading to the activation of CDC2 and CDK2 can be regulated independently. Both positive regulators of CDK activity like cyclins and CDKs, and negative regulators of CDK activity like p21CIP1/WAF1 and Thr14/Tyr15 phosphorylation were up-regulated in HCC. Conclusion: CDC2 and CDK2 are activated in HCC, and this may be due to a complex interplay between the level of the cyclin, CDK, CDK inhibitors, and inhibitory phosphorylation. [source] Meta-analysis of risk for relapse to substance use after transplantation of the liver or other solid organs,LIVER TRANSPLANTATION, Issue 2 2008Mary Amanda Dew For patients receiving liver or other organ transplants for diseases associated with substance use, risk for relapse posttransplantation is a prominent clinical concern. However, there is little consensus regarding either the prevalence or risk factors for relapse to alcohol or illicit drug use in these patients. Moreover, the evidence is inconsistent as to whether patients with pretransplantation substance use histories show poorer posttransplantation medical adherence. We conducted a meta-analysis of studies published between 1983 and 2005 to estimate relapse rates, rates of nonadherence to the medical regimen, and the association of potential risk factors with these rates. The analysis included 54 studies (50 liver, 3 kidney, and 1 heart). Average alcohol relapse rates (examined only in liver studies) were 5.6 cases per 100 patients per year (PPY) for relapse to any alcohol use and 2.5 cases per 100 PPY for relapse with heavy alcohol use. Illicit drug relapse averaged 3.7 cases per 100 PPY, with a significantly lower rate in liver vs. other recipients (1.9 vs. 6.1 cases). Average rates in other areas (tobacco use, immunosuppressant and clinic appointment nonadherence) were 2 to 10 cases per 100 PPY. Risk factors could be examined only for relapse to any alcohol use. Demographics and most pretransplantation characteristics showed little correlation with relapse. Poorer social support, family alcohol history, and pretransplantation abstinence of ,6 months showed small but significant associations with relapse (r = 0.17-0.21). Future research should focus on improving the prediction of risk for substance use relapse, and on testing interventions to promote continued abstinence posttransplantation. Liver Transpl 14:159,172. 2008. © 2008 AASLD. [source] Serotonin and Parkinson's disease: On movement, mood, and madness,MOVEMENT DISORDERS, Issue 9 2009Susan H. Fox MRCP Abstract An appreciation of the multiple roles that serotonin (5-HT) may play in Parkinson's disease (PD) has increased in recent years. Early pathological studies in PD demonstrated nonselective reductions of 5-HT in brain tissue but little correlation to comorbidities such as dyskinesia and mood disturbance. This, combined with treatment failures using serotonergic drugs in comparison to levodopa, meant the field was largely neglected until recently. The multitude of subtypes of 5-HT receptors in the brain and an increased understanding of the potential function 5-HT may play in modulating other neurotransmitter systems, including dopamine, GABA, and glutamate, have meant an expansion in efforts to develop potential serotonergic drugs for both motor and nonmotor symptoms in PD. However, several unanswered questions remain, and future studies need to focus on correlating changes in 5-HT neurotransmission in both pathological and in vivo imaging studies with a full clinical phenotype. © 2009 Movement Disorder Society [source] Review: Neuropathology of acute phase encephalitis lethargica: a review of cases from the epidemic periodNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2009L. L. Anderson Introduction: Encephalitis lethargica (EL), an epidemic disease of the early 20th century, has continued to be diagnosed sporadically since that time, including a report of 20 new cases in 2004. Many of the recent case reports state that the primary neuropathology of acute EL consists of inflammatory changes and lesions within the midbrain, basal ganglia and substantia nigra. However, the neuropathology of acute EL cases from the epidemic period was actually much more widespread. Methods: In order to characterize the neuropathology of acute phase EL, we developed a database of EL pathology based on 112 cases from the years 1915 to 1940, of which most died within 2 weeks of EL onset. Results: Our analysis revealed that cortical damage was prevalent in 75% of the 112 cases; damage to the meninges and brainstem occurred in approximately half of the cases; and the substantia nigra was damaged in only 13% of these acute cases. We also found that after 1921, damage to cranial nerve nuclei was not reported. An analysis of the neuropathology and clinical symptoms revealed little correlation. Conclusions: Based on these findings, putative modern cases of acute EL with MRI/CT indicated lesions confined solely to the midbrain, brainstem, and/or basal ganglia should not be considered, consistent with that reported during epidemic period. [source] The effects of age and sex on chondroitin sulfates in normal synovial fluidARTHRITIS & RHEUMATISM, Issue 8 2002Yoshihito Nakayama Objective To examine how age and sex influence chondroitin sulfates (CS) in normal synovial fluid, we measured the concentrations of chondroitin 6-sulfate (C6S), chondroitin 4-sulfate (C4S), and hyaluronic acid (HA) in healthy subjects of different ages. Methods Synovial fluid samples were obtained from 82 healthy volunteers, ages 20,79 years. Results The concentrations of CS and HA and the C6S:C4S ratio varied with age. Their values were highest between 20 and 30 years of age, and thereafter they showed a tendency to decrease. Statistically, the C6S concentration and the C6S:C4S ratio at ages 60,70 years were significantly lower than those at 20,30 years of age. There was also a clear between-sex difference, in which the CS concentrations and the C6S:C4S ratio in women were significantly lower than those in men (P = 0.0003 for C6S, P = 0.02 for C4S, P = 0.002 for C6S:C4S ratio). In sharp contrast, little between-sex difference was found in the HA concentration. In multiple regression analysis, age correlated strongly with the C6S concentration and the C6S:C4S ratio (r = ,0.521 and r = ,0.617, respectively), weakly with the C4S concentration (r = ,0.202), and moderately with the HA concentration (r = ,0.483). Sex showed a weak correlation with the concentrations of C6S and C4S and the C6S:C4S ratio (r = 0.307, r = 0.225, and r = 0.237, respectively), and little correlation was seen between sex and the HA concentration. Conclusion The CS concentrations and the sulfation patterns in normal synovial fluid vary with age and sex, and these physiologic variations need to be taken into account when using synovial fluid CS as markers for arthritic conditions. [source] Small revisions to predicted distances around metal sites in proteinsACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2006Marjorie M. Harding A new analysis has been made of distances around metal sites in protein structures in the Protein Data Bank determined with resolution ,1.25,Å and equivalent distances have been extracted from the Cambridge Structural Database. They are for the metals Na, Mg, K, Ca, Mn, Fe, Co, Cu, Zn and the donor atoms O of water, O of Asp and Glu, O of the main-chain carbonyl group, N of His and S of Cys. Some revisions are recommended to the tables of `target distances' previously given [Harding (2001), Acta Cryst. D57, 401,411; Harding (2002), Acta Cryst. D58, 872,874]. As well as small changes in many distances and a large improvement for Mg,Ocarboxylate, the table includes an indication of how reliable each prediction may be. Special attention was given to carboxylate interactions. When the carboxylate group is monodentate, the M,Ocarboxylate distance is well defined, but for bidentate carboxylate groups a wide range of distances is allowable; when the metal is Co, Cu or Zn the M,O1 and M,O2 distances are clearly inversely correlated; for the more purely electrostatic interactions involving Na, K and Ca there is a wider scatter of distances and little correlation. [source] A clinical classification of the status of the pulp and the root canal systemAUSTRALIAN DENTAL JOURNAL, Issue 2007PV Abbott Abstract Many different classification systems have been advocated for pulp diseases. However, most of them are based on histopathological findings rather than clinical findings which leads to confusion since there is little correlation between them. Most classifications mix clinical and histological terms resulting in misleading terminology and diagnoses. This in turn leads to further confusion and uncertainty in clinical practice when a rational treatment plan needs to be established in order to manage a specific pathological entity. A simple, yet practical classification of pulp diseases which uses terminology related to clinical findings is proposed. This classification will help clinicians understand the progressive nature of the pulp disease processes and direct them to the most appropriate and conservative treatment strategy for each condition. With a comprehensive knowledge of the pathophysiology of pain and inflammation in the pulp tissues, clinicians may accomplish this task with confidence. [source] | |||||||||||||