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PubMed2004

Does socioeconomic status explain racial differences in urinary incontinence knowledge?

OBJECTIVE: This study was undertaken to discover whether urinary incontinence knowledge differs between racial/ethnic groups. If incontinence knowledge differs between racial/ethnic groups, is the difference explained by socioeconomic status (SES). STUDY DESIGN: In this cross-sectional study, 212 women from 3 counties in California were interviewed by telephone. Urinary incontinence knowledge was measured by an Incontinence Quiz. SES was calculated. Race was categorized as white or minority (non-Hispanic black, Hispanic, and other). RESULTS: White women scored better than minority women on the Incontinence Quiz (6.16 +/- 2.86 vs 5.46 +/- 2.66, P=.071). Higher SES was significantly associated with higher Incontinence Quiz total score (r=0.177, P=.010). Racial differences in Incontinence Quiz total score no longer trended toward significance after adjusting for SES in multivariable analysis. Race/ethnicity and SES were analyzed for association with each question of the Incontinence Quiz CONCLUSION: Socioeconomic status explains racial differences in total urinary incontinence knowledge. Consideration of socioeconomic status may improve the effectiveness of urinary incontinence educational programs.

Adult↗
PubMed2006

Explaining school children's fruit and vegetable consumption: the contributions of availability, accessibility, exposure, parental consumption and habit in addition to psychosocial factors.

We studied the contributions of parental fruit and vegetable (F&V) consumption, availability and accessibility of F&V in the home, exposure to F&V, and habit, in addition to psychosocial factors, in explaining F&V consumption in 4-12-year-old children. Furthermore, we looked for effect modification by ethnicity and gender. Children's parents (n = 1739) completed a questionnaire assessing psychosocial and additional factors regarding their children's F&V consumption. Consumption was assessed by a food-frequency questionnaire. The model explained the children's F&V consumption better when the additional factors were included (R2 = .49 and R2 = .50 for fruit consumption, and R2 = .33 and R2 = .33 for vegetable consumption). Stepwise multi-level regression analyses revealed that habit was the most influential correlate of F&V consumption. It is concluded that nutrition education interventions aimed at stimulating F&V consumption among children should take into account that the consumption of fruit and that of vegetables are clearly different behaviors, with different influencing factors for boys and girls and children of native or non-native background. Furthermore, interventions to increase F&V consumption should include strategies aimed at making these behaviors habitual.

Adult↗
PubMed2005

Loop model: mechanism to explain partial gene duplications in segmented dsRNA viruses.

Gene rearrangements in a head-to-tail fashion have been described several times for gene segments of the rota-, phytoreo-, and orbiviruses. Several mechanisms have been proposed to explain the occurrence of partial duplications, however, none of these models has been fully satisfactory to explain the occurrence of all the observed duplicated genes. Based on recently available structural data about the lambda3 RNA-dependent-RNA-polymerase of reoviruses, we propose the 'loop model' as a plausible explanation for the occurrence of partial gene duplications in dsRNA viruses.

Computer Simulation↗
PubMed2005

Head and neck cancer: to what extent can psychological factors explain differences between health-related quality of life and individual quality of life?

AIMS: To assess the extent to which individualised quality of life (QoL) was related to standardised health-related quality of life (HR-QoL), and to assess how much of the variation in each of these measures could be explained by psychological variables. METHODS: Fifty-five patients with newly diagnosed head and neck cancer completed the following outcome measures: the Patient Generated Index (PGI), the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 and the Short Form 12 version 2 (SF-12v2). Explanatory factors were measured with the following: the Illness Perceptions Questionnaire-Revised (IPQ-R), the Beliefs about Medicines Questionnaire (BMQ), the Hospital Anxiety and Depression Scale (HADS), and the Brief COPE (a shortened version of the COPE). MAIN FINDINGS: Standardised and individualised QoL measures were correlated only partly. The PGI correlated only with EORTC QLQ-C30 domains of emotional and cognitive functioning and SF-12 domains of mental health, emotional role, social, and physical role. The underlying psychological factors explaining each of the three outcome measures were different. CONCLUSIONS: Respondent-generated measures such as the PGI could be used as an adjunct to more standardised measures of HR-QoL clinically. This has implications for assessing the impact of head and neck cancer on individualised QoL and also for improving patients' outcome through interventions aimed at targeting underlying psychological factors.

Activities of Daily Living↗
PubMed2006

The reinnervation pattern of wounds and scars may explain their sensory symptoms.

Anaesthesia, pruritus and pain are common in cutaneous scars. The reinnervation pattern of healing wounds and scars might help to explain these symptoms, as sensory neurotransmitters are known to be mediators of inflammation and healing. We quantified the regeneration patterns of blood vessels and nerves in excisional skin wounds as they matured into scars. Mice underwent 1cm(2) full thickness skin excisions. Wounds were harvested between five and 84 days. Sections underwent immunohistochemical staining for protein gene product 9.5 (PGP9.5) a pan-neuronal marker, and the sensory neuropeptides calcitonin gene related peptide (CGRP) and substance P (SP). The endothelial marker von Willebrand factor (VWF) was used to allow co-localisation and quantification of blood vessels. Nerve fibre density was quantified at multiple sites within wounds. There was no difference in the reinnervation/revascularisation pattern between peripheral and central sites. The density of PGP9.5, CGRP, SP and VWF peaked between 14 and 42 days, and levels of PGP9.5, CGRP and VWF all decreased to approximately those found in unwounded skin by 84 days (mature scar). SP levels, however, remained elevated at approximately twice the density found in unwounded skin. Increased densities of SP and CGRP in healing wounds could explain the unpleasant sensory symptoms of healing wounds.

Animals↗
PubMed2005

The binding of aristolochic acid I to the active site of human cytochromes P450 1A1 and 1A2 explains their potential to reductively activate this human carcinogen.

Aristolochic acid (AA), a naturally occurring nephrotoxin and carcinogen, has been associated with the development of urothelial cancer in humans. Using the 32P-postlabeling assay we showed that AAI is activated by human recombinant cytochrome P450 (CYP) 1A1, CYP1A2 and NADPH:CYP reductase to species generating DNA adduct patterns reproducing those found in renal tissues from humans exposed to AA. 7-(Deoxyadenosin-N6-yl)aristolactam I, 7-(deoxyguanosin-N2-yl)aristolactam I and 7-(deoxyadenosin-N6-yl)aristolactam II were identified as AA-DNA adducts formed from AAI by the enzymes. The formation of these AA-derived DNA adducts indicates that all the human enzymes reduce the nitro group of AAI to the putative reactive cyclic nitrenium ion responsible for adduct formation. The concentrations of AAI required for its half-maximum DNA binding were 38, 65 and 126 microM AAI for reductive activation by human CYP1A2, CYP1A1 and NADPH:CYP reductase, respectively. CYP1A1 and 1A2 homology modeling followed by docking of AAI to the CYP1A1 and 1A2 active centers was utilized to explain the potential of these enzymes to reduce AAI. Models of human CYP1A1 and 1A2 were constructed on the basis of the crystallographic structure of truncated mammalian CYP enzymes, CYP2B4, 2C5, 2C8, 2C9 and 3A4. The in silico docking of AAI to the active sites of CYP1A1 and 1A2 indicates that AAI binds as an axial ligand of the heme iron and that the nitro group of AAI is in close vicinity to the heme iron of CYP1A2 in an orientation allowing the efficient reduction of this group observed experimentally. The orientation of AAI in the active centre of CYP1A1 however causes an interaction of the heme iron with both the nitro- and the carboxylic groups of AAI. This observation explains the lower reductive potential of CYP1A1 for AAI than CYP1A2, detected experimentally.

Amino Acid Sequence↗
PubMed2004

Limited effects of post-ischemic NHE blockade on [Na+]i and pHi in rat hearts explain its lack of cardioprotection.

OBJECTIVE: Na+/H+ exchanger (NHE) blockade fails as reperfusion therapy in patients with acute myocardial infarction. In experimental studies, the reports on the efficacy of NHE blockade only during reperfusion are inconsistent. Differences in the severity of ischemia and in drug delivery may explain these inconsistencies. Little is known about the primary goal of post-ischemic NHE blockade, i.e. reduction of Na+i overload. METHODS: Isolated rat hearts were subjected either to 60 min of low flow (0.2 ml/min) ischemia or 25 min of zero flow ischemia. Hearts were reperfused with or without the selective NHE blocker cariporide added to the perfusate. [Na+]i and pHi were measured with simultaneous 23Na and 31P NMR spectroscopy. RESULTS: After 60 min of low flow ischemia [Na+]i had risen to 424 +/- 14% of baseline and pHi was 6.36 +/- 0.03. After low flow ischemia [Na+]i and pHi recovered similarly in treated and untreated hearts. Recovery of the rate pressure product (RPP) was poorly in both groups. After 25 min of zero flow ischemia [Na+]i had risen to 279 +/- 7% of baseline and pHi was 6.12 +/- 0.02. NHE blockade after zero flow ischemia caused [Na+]i to decrease during the first 30 s of reperfusion, followed by a partial and transient rise during the second 30 s. Untreated hearts showed a very small rise in [Na+]i during the first minute. pHi recovered 30 s slower in cariporide treated hearts than in untreated hearts (p<0.05). No effect of cariporide on RPP could be detected since RPP recovered fully in untreated hearts. The end diastolic pressure, however, was increased during reperfusion to a similar extent in both groups. CONCLUSION: The lack of cardioprotection under these specific conditions of zero flow and low flow ischemia can be explained by the fact that NHE blockade only resulted in a small and transient effect on [Na+]i and pHi.

Animals↗
PubMed2005

A new hypothesis to explain the coexistence of n species in the presence of a single resource.

This paper presents a hypothesis allowing us to explain the coexistence of several species (here micro-organisms) in competition on a single resource (called a substrate) in a chemostat. We introduce a new class of kinetics that does not only depend on the substrate concentration in the medium, but also on the biomass concentration. From the study of elementary interactions (i) between micro-organisms, (ii) between micro-organisms and their environment in which they grow and from simulations, we show that this modelling approach can be interpreted in terms of substrate diffusion phenomena. A rigorous study of this new class of models allows us to hypothesize that abiotic parameters can explain the fact that an arbitrarily large number of species can coexist in the presence of a unique substrate.

Cell Physiological Phenomena↗
PubMed2004

Does a form of 'entanglement' between people explain healing? An examination of hypotheses and methodology.

Quantum entanglement is a phenomenon in which entangled systems exhibit correlations that cannot be explained by classical physics. It has recently been suggested that a similar process occurs between people and explains anomalous phenomena such as healing. This paper explores the hypothesis that the therapeutic interaction involves some kind of 'entanglement' between people. There are several different versions of the theory that entanglement is possible between people: the versions differ in the way entanglement between people is derived, and the way it has a therapeutic effect. The two main versions are generalised, specific entanglement, and global, emergent entanglement-specific entanglement. Two research ideas are presented for testing the hypothesis of entanglement between people, both of which are based on predicting variation in outcome in naturally occurring contexts (the naturalistic observational study).

Attitude to Health↗
PubMed2005

CARD15/NOD2 polymorphisms do not explain concordance of Crohn's disease in Swedish monozygotic twins.

BACKGROUND: CARD15/NOD2 polymorphisms are associated with Crohn's disease. There is a high concordance for disease and disease phenotype in monozygotic twin pairs with Crohn's disease. AIM: We studied CARD15/NOD2 polymorphisms in a Swedish, population-based cohort of monozygotic twins with Crohn's disease to assess whether these variants explain disease concordance. SUBJECTS AND METHODS: Twenty-nine monozygotic twin pairs (concordant n=9, discordant n=20) with Crohn's disease and 192 healthy controls were investigated for the CARD15/NOD2 variants Arg702Trp, Gly908Arg and Leu1007fsinsC. RESULTS: CARD15/NOD2 mutations were found in 5/38 (13%) twins with Crohn's disease, corresponding to a total allele frequency of 6.6%. Only 2/9 concordant twin pairs carried any of the variants and the remaining seven were wild type genotype. The total allele frequency was 4.4 times higher (95% confidence interval 1.0-21.5, p=0.06) in concordant twins than in discordant ones, 11.1% versus 2.5%. In healthy controls the total allele frequency was 2.6%. CONCLUSIONS: CARD15/NOD2 polymorphisms contribute but do not alone explain concordance of Crohn's disease in monozygotic twins and, at least in a Swedish population, other polymorphisms are required. The low occurrence of CARD15/NOD2 mutations in the study and other Northern European populations suggests that these variants are of less importance in Northern Europe.

Adolescent↗
PubMed2004

Demographic heterogeneity explains age-specific patterns of genetic variance in mortality rates.

The genetic variance of mortality rates in Drosophila melanogaster increases with age early in life, but declines at intermediate ages. A simulation study was done in order to evaluate two competing explanations for this age-specific pattern: (1) demographic heterogeneity, and (2) binomial sampling effects. The pattern can be explained by demographic heterogeneity among and within genotypes. In contrast, binomial sampling variance is not sufficient to explain this age-specific pattern of genetic variance in mortality rates. A previous publication that rejected the 'heterogeneity explanation' in favor of binomial sampling is shown to be mistaken.

Aging↗
PubMed2005

Complex pattern formation of marine gradient bacteria explained by a simple computer model.

We report on the formation of conspicuous patterns by the sulfide-oxidizing bacterium Thiovulum majus and a recently described vibrioid bacterium. These microaerophilic bacteria form mucus veils on top of sulfidic marine sediment exhibiting regular spaced bacterial patterns (honeycombs, interwoven bands, or inverse honeycombs). A simple qualitative computer model, based on chemotaxis towards oxygen and the ability of the bacteria to induce water advection when attached, can explain the formation of the observed patterns. Our study shows that complex bacterial patterns in nature can be explained in terms of chemotaxis and resource optimisation without involvement of cell-cell signalling or social behavior amongst bacteria.

Bacterial Physiological Phenomena↗
PubMed2004

A modified and unifying neurogenic hypothesis can explain the natural history of chronic Chagas heart disease.

The pathogenesis of chronic Chagas disease still is an unresolved and controversial issue. Parasite persistence and autoimmune responses cannot explain the spectrum of chronic Chagas disease. However, a modified neurogenic hypothesis, concerning the timing and mechanisms responsible for the cardiac parasympathetic damage and for the activation of the sympathetic nervous system and of other neurohormonal systems, unifies cardiac remodelling and neurohormonal activation to explain most of the events of the natural history of Chagas disease.

Animals↗
PubMed2004

Can changes in sexual behaviors among high school students explain the decline in teen pregnancy rates in the 1990s?

PURPOSE: To explore the utility of using national data from high school students to explain changes in national declines in pregnancy rates. Although declines in teen pregnancy and birthrates in the 1990s have been welcome news to those interested in adolescent health and welfare, the reasons for these declines are not readily apparent. Previous attempts to explain these declines focused on the period before 1995 and did not directly calculate the impact of improved contraceptive use. METHODS: The national Youth Risk Behavior Survey provided estimates for sexual activity and contraceptive use among teens aged 15-17 years between 1991 and 2001 (n = 31,058). These data were combined with method-specific contraceptive failure rates (CFRs) derived from the 1988 and 1995 National Survey of Family Growth and pregnancy rates from the National Vital Statistics System. We calculated weighted-average CFRs (WACFR) and used the annual rate of change in the WACFR and sexual activity to estimate their relative contributions to the annual change in risk of pregnancy. Weighted least-squares regression in SUDAAN was used to test change over time. RESULTS: Between 1991 and 2001, annual rates of change in sexual behaviors were -1.7% for sexual experience and -1.6% for the WACFR. Improvements in WACFR resulted primarily from a decline in use of withdrawal (from 20% to 13%) and use of no method (from 17% to 13%) and an increase in condom use (40% to 51%). Recent sexual intercourse (i.e., intercourse during the past 3 months among teens who had ever had intercourse) did not change over time. The change in the estimated risk of pregnancy closely approximated the annual decline in the pregnancy rates for blacks and Hispanics but underestimated the actual decline for whites. Overall, 53% of the decline in pregnancy rates can be attributed to decreased sexual experience (95%CI 26% to 79%) and 47% to improved contraceptive use (95%CI 21% to 74%). CONCLUSIONS: Use of school-based behavior data reflects well the pregnancy experience for school-age black and Hispanic adolescents, but does not track well with the pregnancy risk of white adolescents. Care should be taken in attributing changes in pregnancy rates to changes in behavior, given broad confidence intervals around these estimates. These data suggest that both delayed initiation of sexual intercourse and improved contraceptive practice contributed equally to declines in pregnancy rates among high school-aged teens during the 1990s; however, estimates varied among racial and ethnic groups.

Adolescent↗
PubMed2006

The challenge of cross-cultural assessment--The Test of Ability To Explain for Zulu-speaking Children.

UNLABELLED: A culturally appropriate test, The Test of Ability To Explain for Zulu-speaking Children (TATE-ZC), was developed to measure verbal problem solving skills of rural, Zulu-speaking, primary school children. Principles of 'non-biased' assessment, as well as emic (culture specific) and etic (universal) aspects of intelligence formed the theoretical backdrop. In addition, specific principles relating to test translation; test content; culturally appropriate stimulus material; scoring procedures and test administration were applied. Five categories of abstract thinking skills formed the basis of the TATE-ZC. These were: (a) Explaining Inferences, (b) Determining Cause, (c) Negative Why Questions, (d) Determining Solutions and (e) Avoiding Problem. The process of test development underwent three pilot studies. Results indicate that the TATE-ZC is a reliable and valid test for the target population. A critical analysis of the efficacy of creating a test of verbal reasoning for children from the developing world concludes the article. LEARNING OUTCOMES: As a result of this activity (1) the participant will have a clearer understanding of the principles that need to be followed when developing culturally appropriate test material; (2) the participant will understand the process of developing culturally appropriate test material for non-mainstream cultures; (3) the participant will be able to apply the process and principles to other cross-cultural testing situations.

Child↗
PubMed2006

Plant-induced changes in soil chemistry do not explain differences in uranium transfer.

A greenhouse experiment was set up with maize, ryegrass, Indian mustard, wheat and pea to evaluate to what extent differences in uranium (U) transfer factors can be explained by root-mediated changes in selected soil properties. The experiment involved an acid and an alkaline soil contaminated with (238)U. U soil-to-shoot transfer factors (TFs) ranged between 0.0005 and 0.021 on the acid soil and between 0.007 and 0.179 on the alkaline soil. Indian mustard showed the highest U uptake in shoots and maize the lowest. The root TFs, only available for the acid soil, ranged from 0.58 for maize and Indian mustard to 1.38 for ryegrass. The difference in U uptake between the two soils and the five plants was only partially explained by the different initial U concentrations in soil solution or differences in soil properties in the two soils. However, we obtained a significant relation for differences in shoot TFs observed between the two soils when relating shoot TFs with concentration of UO(2)(2+) and uranyl carbonate complexes in soil solution (R(2)=0.88). The physiological mechanisms by which root-to-shoot U transfer is inhibited or promoted seemed at least as important as the plant-induced changes in soil characteristics in determining soil-to-shoot TFs.

Plants↗
PubMed2005

The electric field induced by light can explain cellular responses to electromagnetic energy: a hypothesis of mechanism.

When cells are irradiated with visible and near-infrared wavelengths a variety of stimulatory effects are observed in their metabolism. To explain the observed light effects, researchers try to identify the chromophores that are involved in the processes. However, the mechanism of light absorption by a chromophore does not explain many of the experimental observations and therefore the primary mechanism for cellular light responses remains unproven. In addition to the ability of photons to produce electronic excitation in chromophores, light induces a wave-like alternating electric field in a medium that is able to interact with polar structures and produce dipole transitions. These dipole transitions are analyzed in the present article at different cellular and biochemical levels, leading to the proposal that the primary mechanism for the observed light effects is related to the light-induced electric field.

Adenosine Triphosphate↗
PubMed2006

Methodological issues concerning lifetime medically unexplained and medically explained symptoms of the Composite International Diagnostic Interview: a prospective 11-year follow-up study.

OBJECTIVE: The objectives of this study were (a) to elucidate the methodological problems arising when examining lifetime symptom data by exploring the accuracy of recall of medically unexplained symptoms (MUS) and medically explained symptoms (MES) in the general population, based on interviews using the Composite International Diagnostic Interview (CIDI) Somatoform Section C, in 1990 and 2001, and (b) to find predictors for failure at follow-up to recall symptoms reported previously at baseline (i.e., symptoms "lost"). METHODS: Four hundred twenty-one persons (response rate, 69.6%; 242 women and 179 men) were reinterviewed in 2001 from a baseline population of 605. Thirty-eight clinically significant MUS and MES were assessed. Linear multiple regression analyses with the numbers of MUS-lost (medically unexplained symptoms lost to recall) and MES-lost (medically explained symptoms lost to recall) as dependent variables were undertaken to find factors affecting symptom loss. RESULTS: A wide range of individual symptoms (22-100%) were lost to recall at follow-up, indicating a large degree of measurement error, mainly due to faulty recall. The number of symptoms recalled when they were grouped was better (approximately 50% for "1-3" symptoms). Recall variability and MUS/MES transition over time undermined the credibility of this distinction. Gender and age emerged as significant (P<.01) predictors for MUS-lost, and a decrease in physical morbidity for MES-lost. Men tended to forget more symptoms than women, and younger respondents with high levels of baseline MUS remembered slightly better at follow-up. CONCLUSION: Lifetime symptom data elicited in community surveys by such instruments as the CIDI should be viewed with caution. Methodological errors weakening data credibility could lead to false impressions of true change over time. A MUS/MES distinction is difficult to maintain.

Adult↗