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At least 199 records · Page 11Linked to original sources
PubMed1998

The social environment and health in rheumatoid arthritis: marital quality predicts individual variability in pain severity.

OBJECTIVE: To examine prospective relations between a wide array of measures of social functioning and pain, while controlling for disease duration and activity and functional grade. METHODS: As part of a larger study on health care utilization, longitudinal data were collected from 136 Dutch and 98 German outpatients on clinical status and pain. Social data included information on sexual handicap, spouse behavior, loneliness, daily emotional support, and the maintenance of pleasurable life domains. Pain severity was assessed at baseline and 12 months later with standard measures of pain and analyzed with hierarchical regressions. RESULTS: Social measures obtained at baseline were consistently associated with pain at followup. Depression was a moderate correlate of pain in the Dutch and German samples. The regressions revealed that patient reports of negative spouse behavior (such as avoidance and critical remarks) and baseline depression predicted worse pain outcome, and this association remained significant in analyses controlling for baseline pain. The level of formal education was a weak correlate of disability, emotional support, and pain. Daily emotional support and social life domains associated with positive affect had an indirect influence on outcome. The absence of strong rather than weak social ties was the component of the loneliness construct linked to pain. These associations between social prognostic factors and pain severity, however, were mediated by psychological functioning at baseline. CONCLUSION: The social environment was found to operate on the core health outcome, pain severity, via several pathways. Social functioning may be affected by rheumatoid arthritis (RA) progression, but it also appears to form a determinant of future health outcome. Not only the status of being married but also the quality of the relationship in terms of long-term stress and emotional support may be useful prognostic factors in RA.

Activities of Daily Living↗
PubMed2000

[Intra-individual variability of blue-yellow perimetry].

BACKGROUND: Short wavelength automated perimetry (SWAP) is a sensitive method in detection of early glaucomatous damage. In this study, we compared intra-subject variability of global indices of SWAP and conventional white-on-white perimetry (WWP) in normal clinical conditions (without correction for lens yellowing). METHODS: SWAP and WWP (Humphrey field analyzer, 24-2 field, full threshold strategy) was performed in 68 eyes with glaucoma or glaucoma suspect and at the same day. The tests were repeated within 45 days (mean follow-up 16 +/- 13 days). RESULTS: At the follow-up test the mean defect was significantly reduced for both conditions, more pronounced for SWAP. Pattern standard deviation remained statistically equal for both conditions. The coefficient of correlation of baseline to follow-up was for SWAP PSD 0.88 with a slope of 1.05, for WWP PSD 0.7 with a slope of 0.83. The coefficient of variation for PSD was 17% for SWAP and 34% for WWP. CONCLUSIONS: The low intraindividual variability of SWAP enables early detection of glaucomatous field damage in the follow-up.

Adult↗
PubMed2006

Assessment of dosing impact on intra-individual variability in estimation of parameters for basic indirect response models.

The application of D-optimization and the assessment of bias and precision of parameter estimates for four basic pharmacodynamic (PD) indirect response (IDR) models for ascending doses was examined using simulated data. While D-optimization provided four sampling times, each IDR model was used to generate eight data points per dose level. The PD parameters were: input rate constant (k (in)), disposition rate constant (k (out)), capacity constant (I (max) or S (max)), and sensitivity constant (IC (50) or SC (50)). A monoexponential pharmacokinetic function was applied with single doses increased by a factor of 10 to generate responses that vary from weak to fully saturable. For each dose, 100 replications of response data were simulated using independent normally distributed errors of CV = 20%. The original IDR model was fitted and PD parameters estimated. Histograms and descriptive statistics were generated. All parameters exhibited asymmetric distributions with positive coefficients of skewness except for I (max). Higher doses resulted in unbiased estimates of all PD parameters. The precision of parameter estimates improved with increasing doses except for IC (50) and SC (50) indicating that a single dose experimental design cannot be corrected by increasing dose in order to improve precision of estimates of IC (50) or SC (50). Highest variability was for IC (50) and SC (50) parameters. This study provides new insights into optimum study designs and recovery of parameters for basic IDR models.

Biological Availability↗
PubMed1982

Benzodiazepine effects upon Geller-Seifter conflict test in rats: analysis of individual variability.

The aim of the present study was to investigate in a large group of "drug sophisticated" animals the effect of several doses of oxazepam upon conflict behavior. To this end 43 rats, trained according to the original Geller-Seifter paradigm, were tested with 5 doses (6.25, 12.5, 20.9, 25, and 50 mg/kg IP) of oxazepam. In addition the influence of prior drug experience on the effects of benzodiazepines on punished and unpunished responding was investigated comparing data from the same animals relative to a single oxazepam treatment before and after "drug sophistication." It was found that: (1) after "drug sophistication" oxazepam effect upon the unpunished schedule is decreased, while the disinhibitory action upon punished behavior is increased, unchanged or even decreased; (2) sedative and anticonflict activities of the drug cannot be explained in terms of rate dependency and are independently assessable since, even when unpunished responding is lowered by high doses, the anxiolytic effect is masked in only 27% of the cases; (3) about 20% of the animals appear to be insensitive to the anticonflict effect of oxazepam; (4) the responsiveness to the anxiolytic effect of the drug is related to the shock intensities given during training and to the animal variability under control conditions.

Animals↗
PubMed2005

Inter-individual variability during morning choruses in Japanese quail males (Coturnix coturnix japonica).

We compared the organization of dawn choruses in five groups of Japanese quail, Coturnix coturnix japonica, males (four groups of kin-related males and one group of unrelated males). We documented the structure of chorus groups: one male sang much more than the others during the dawn peak in four of the five groups, and this regardless of the number of males in the group. The dominant singers were then removed from two similar-sized groups, one of kin-related (K3) and the other of unrelated (NK) males. The quantity of song emitted by the remaining NK males was modified, but not that emitted by the K3 males.

Animals↗
PubMed2005

Gene - environment interactions determine the individual variability in cocaine self-administration.

Research into factors that determine the propensity to self-administer cocaine has shown that stressors can determine the amount of cocaine self-administered as well as the rate of acquisition. However, the interaction between the genetic make-up of the animal and stress is unknown. This study investigated this interaction by using the genetic animal model consisting of apomorphine susceptible (APO-SUS) and unsusceptible (APO-UNSUS) rats. Animals were allowed to self-administer 0.25 mg/kg cocaine under stressful and habituated conditions. This study revealed that the amount of cocaine consumed was highly dependent on the genetic make-up of the animal as well as the amount of stress during self-administration. Under habituated circumstances the APO-UNSUS rats took far more cocaine than the APO-SUS rats. Under stressful circumstances, however, the APO-SUS rats took far more cocaine than the APO-UNSUS rats. This difference in the amount consumed by APO-SUS and APO-UNSUS rats is likely to be due to the specific neurobiological features of their dopaminergic and, possibly, noradrenergic system as well as the reactivity of their HPA-axis. It is suggested that the amount of a drug consumed and, accordingly, its addictive potential and 'drug-vulnerability' are determined by the interaction between the genetic make-up of the animals and stress, and not by either component alone.

Analysis of Variance↗
PubMed1997

Intra-individual variability of fibrinogen levels.

Elevated fibrinogen concentrations are recognized as playing an important role in the pathogenesis of atherosclerosis. In the framework of a risk factor survey in 342 middle-aged working men, screened twice over a period of five months, plasma fibrinogen levels were found to be fairly unstable as large discrepancies between both measurements were observed. Due to a substantial proportion of within-person variability, the reliability coefficient was only R = 0.56. Repeatability was highest in higher educated and physically more active men. Our data suggest that the impact of elevated fibrinogen levels on the development of ischemic heart disease and stroke, is likely to be under-estimated.

Adult↗
PubMedDate not supplied

Search for genetic determinants of individual variability of the erythropoietin response to high altitude.

There is marked variability in the erythropoietin (Epo) and erythrocytic response to extreme high altitude among mountain dwellers, as well as to hypoxic training among athletes, at least in part because of the variation in the erythropoietic response to hypoxia. We hypothesized that this may be genetically determined. Forty-eight athletes were exposed to 24 h of simulated altitude to 2,800 m in a hypobaric chamber. Serum Epo concentrations were determined at baseline and after 24 h. The Epo responses ranged from -41 to 433% of baseline values after 24 h at simulated altitude. The association of the Epo response to hypoxia with the EPO gene and eight genes involved in Epo regulation utilizing 16 polymorphic dinucleotide repeats was examined. Initial analysis showed a possible association between the EPO gene (marker D7S477) and the increase of the Epo level (P = 0.018). We then tested the possibility that sequence abnormalities in the 3' and 5' hypoxia response elements (3' HRE) and (5' HRE) of the EPO gene could explain the differences in Epo response. We found a 3434 C --> T polymorphism in the 3' HRE sequence. However, this polymorphism showed no correlation with the differences in Epo levels. Further, when we analyzed two additional markers flanking the EPO gene by less than 0.3 cM, we found no association of the allelic variants at these loci with the Epo hypoxic response. In conclusion, we could find not convincing association between markers tightly linked to EPO or eight genes involved in Epo regulation and Epo differential responses to hypoxia.

Adult↗
PubMed2005

Metabolism of antioxidant and chemopreventive ellagitannins from strawberries, raspberries, walnuts, and oak-aged wine in humans: identification of biomarkers and individual variability.

Ellagitannins (ETs) are dietary polyphenols, containing ellagic acid (EA) subunits, with antioxidant and cancer chemopreventive activities that might contribute to health benefits in humans. However, little is known about their metabolic fate. We investigate here the metabolism of different dietary ETs and EA derivatives in humans. Forty healthy volunteers were distributed in four groups. Each group consumed, in a single dose, a different ET-containing foodstuff, i.e., strawberries (250 g), red raspberries (225 g), walnuts (35 g), and oak-aged red wine (300 mL). After the intake, five urine fractions (F) were collected at 8 (F1), 16 (F2), 32 (F3), 40 (F4), and 56 (F5) h. Neither ETs nor EA were detected in urine after LC-MS/MS analysis. However, the microbial metabolite 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one (urolithin B) conjugated with glucuronic acid was detected along the fractions F3-F5 in all of the subjects, independently of the consumed foodstuff. The mean percentage of metabolite excretion ranged from 2.8 (strawberries) to 16.6% (walnuts) regarding the ingested ETs. Considerable interindividual differences were noted, identifying "high and low metabolite excreters" in each group, which supported the involvement of the colonic microflora in ET metabolism. These results indicate that urolithin B (a previously described antiangiogenic and hyaluronidase inhibitor compound) is a biomarker of human exposure to dietary ETs and may be useful in intervention studies with ET-containing products. The antioxidant and anticarcinogenic effects of dietary ETs and EA should be considered in the gastrointestinal tract whereas the study of potential systemic activities should be focused on the bioavailable urolithin B derivatives.

Adult↗