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At least 217 records · Page 12Linked to original sources
PubMed2004

Epithelial ovarian cancer risk by invasiveness and cell type in the Central Valley of California.

OBJECTIVE: To evaluate epithelial ovarian cancer (EOC) risk factors by level of invasiveness and histology. METHODS: A population-based epidemiologic case-control study of EOC was conducted over a 2-year period (January 2000 to December 2001) in 22 counties of Central California that comprise the reporting area for two regional cancer registries. Telephone interviews were conducted with 256 cases and 1122 control frequencies matched on age and ethnicity. The interview obtained information on demographic factors as well as information pertinent to the respondent's menstrual and reproductive experience, use of exogenous hormones, surgical history, and family history of cancer. Adjusted odds ratios were calculated using stratification as well as Logistic regression methods. Analyses were completed by level of invasiveness and cell type. RESULTS: Strong protective associations were observed for use of oral contraceptives and parity. Risk increased with a family history of ovarian, but not breast cancer and age at first birth was positively associated with increased risk. Hormone replacement therapy was associated with increased risk only in long-term users. Many of the relationships were observed only in specific histologic subtypes of EOC. CONCLUSION: Risk of EOC is associated with several lifestyle and environmental exposures but the impact of these effects appears to be dependent upon level of invasiveness and histologic subtypes of EOC. However, the sample size available for analysis limits our statistical power and our ability to analyze data by histologic subtype, thus limiting interpretation of our results.

Adolescent↗
PubMed2000

Population genetics of black abalone, Haliotis cracherodii, along the central California coast.

Over the past three decades, the black abalone, Haliotis cracherodii, has experienced precipitous declines in abundance over portions of its range in southern and central California. The potential for recovery of these populations is dependent in part on dispersal processes; that is, can distant populations serve as sources of recruits to locales that no longer harbor H. cracherodii? Here we use population genetic analysis to assess levels of population subdivision and infer recruitment processes. Epipodial tissue samples were obtained from over 400 black abalone from seven geographic sites between Santa Cruz and Santa Barbara counties in central California. Allelic frequencies were determined for each population at three polymorphic enzyme-encoding loci (GPI, AAT-1 and PGM). Significant allelic frequency differentiation among sites was observed at all three loci. Genetic distance was found to be independent of geographic distance over the approximately 300-km sampling range. In addition, a limited number of DNA sequences (total N=51) were obtained for the mitochondrial cytochrome oxidase subunit I gene (COI) from five of the populations. Since the same common COI haplotype dominated each population, this analysis had little statistical power and failed to detect population structure. The observed level of population differentiation at allozyme loci was three-fold higher than that observed in California red abalone, H. rufescens. The species differ in their breeding period and it is suggested that the relatively short, summer breeding season of black abalone limits dispersal because larvae experience reduced variance in oceanographic conditions relative to red abalone that spawn year-round. Based on these results, rates of recolonization and recovery of locally depressed or extirpated black abalone populations are likely to be slow despite harvest restrictions.

Journal Article↗
PubMed2002

The natural course of MRI white matter hyperintensities.

The rate and extent of progression of white matter hyperintensities (WMH) over time in elderly subjects is yet unclear. These abnormalities may represent an early form of subcortical vascular dementia. As to whether such changes could be used, as a surrogate marker for this subtype of vascular dementia remains to be determined. So far there exists only a very limited number of studies determining the rate, clinical predictors and cognitive consequences of WMH evolution. There is evidence that these changes do progress over time, however the results of the different studies cannot be compared due to methodological differences. The Austrian Stroke Prevention Study reported that 17.9% of normal individuals show progression over time. The only published quantitative data demonstrated an absolute increase of 1.1 cm(3) over an observational period of 4 years in healthy subjects. Diastolic blood pressure, early confluent or confluent WMH at baseline and genetic variants in the angiotensinogen gene are so far the only known predictors of WMH progression. The Austrian Stroke Prevention Study did not find an association between the evolution of WMH and cognitive functioning but the statistical power of this analysis was small and the relationship needs to be further explored.

Aged↗
PubMed2001

The performance of the refractive status and vision profile survey in a contact lens clinical trial.

OBJECTIVE: To evaluate the Refractive Status and Vision Profile (RSVP) questionnaire in a contact lens clinical trial and to assess the feasibility of its use in future trials. DESIGN: Randomized, crossover clinical trial and survey. PARTICIPANTS: The RSVP was administered to 50 contact lens-wearing participants recruited from a large contact lens clinic. METHODS: RSVP scores were calculated for subjects at three outcome visits: (1) baseline, (2) after wearing daily disposable contact lenses, and (3) after wearing disposable extended wear contact lenses. One-sample t tests were used to compare baseline survey scores with those previously reported for the instrument. The relation of survey scores within and between subjects was assessed with repeated measures analysis of variance. Statistical power and sample size calculations were performed to determine the number of subjects required in future studies to detect differences in RSVP subscale scores. MAIN OUTCOME MEASURES: Eight subscale scores (concern, driving, expectations, glare, optical problems, physical and social functioning, problems with corrective lenses, and symptoms) and the overall RSVP score were calculated on the basis of guidelines reported for scoring of the instrument. RESULTS: Five of eight mean subscale scores (concern, expectations, driving, optical problems, and problems with corrective lenses) and the overall score were significantly lower than those previously reported. No differences were found in the following subscales after contact lens treatment: concern, expectations, physical and social functioning, driving, optical problems, problems with corrective lenses, or the overall RSVP score. Significant differences were found on the symptoms (P = 0.03) and glare (P = 0.05) subscales; post hoc testing revealed that the significant differences in these scores occurred between baseline and daily disposable lens wear and not between treatment modalities (daily disposable and disposable extended wear). A sample size of 420 would be required to find clinically relevant significant differences (25%) for all subscales in a similar one-sample clinical trial. A more restrictive difference (10%) would require more than 1100 subjects for four of the nine subscales. CONCLUSIONS: The RSVP questionnaire may not be the appropriate quality-of-life instrument for use in a contact lens clinical trial. The instrument seems to lack sensitivity and discriminative validity in evaluating contact lens treatments.

Adolescent↗
PubMed1996

DNA content proportionality and persistence of radiation-induced chromosomal aberrations studied by FISH.

Chromosome aberrations induced by radiation have been used for the purpose of dosimetry for a long time. Translocations are especially useful for retrospective dosimetry, since they are assumed to be stable. The method of chromosome painting (FISH) has facilitated objective scoring of aberrations considerably. Translocation frequencies, obtained by FISH, for retrospective dosimetry rely on the main assumptions of neutral selection value and that the distribution of aberrations over the chromosomes is a known function of the DNA content of the chromosomes. Data scrutinising the two above-mentioned assumptions indicate deviations from both. Other factors potentially causing problems for retrospective dosimetry, such as inter-individual variations in background and induction patterns, are discussed. Finally, a brief analysis of the statistical power of dosimetry studies shows that establishing low doses (approximately 0.25 Gy) with good precision requires a great effort, which is probably unrealistic for individual dose estimates in epidemiological studies.

Chromosome Aberrations↗
PubMed2003

Heart rate variability during sleep as a function of the sleep cycle.

In this work, in order to evaluate whether autonomic differences distinguish REM sleep and NREM sleep through the whole sleeping period, statistical analysis on spectral power associated with low frequency and high frequency bands were performed on the whole polysomnographic recording, considering the sleep cycle as a unit of sleep. Our results from nine subjects show that power associated with low frequency is higher in REM sleep than in NREM sleep, while power associated with high frequency is significantly higher in NREM sleep than in REM sleep. Differences between REM sleep and NREM sleep are not of the same magnitude within the whole sleep episode and, independent of sleep stages, specific trends are observable in the autonomic control of heart rate during the night.

Adult↗
PubMed2002

Sensory stimulation (TENS): effects of parameter manipulation on mechanical pain thresholds in healthy human subjects.

Transcutaneous electrical nerve stimulation (TENS) is a popular form of electrostimulation. Despite an extensive research base, there remains no consensus regarding the parameter selection required to achieve maximal hypoalgesic effects. The aim of this double blind, sham-controlled study was to investigate the relative hypoalgesic effects of different TENS parameters (frequency, intensity and stimulation site) upon experimentally induced mechanical pain. Two hundred and forty participants were recruited in order to provide statistical analysis with 80% power at alpha = 0.05. Subjects were randomised to one of the six TENS groups, a control, and a sham TENS group (n = 30, 15 males, 15 females, per group). TENS groups differed in their combinations of stimulation; frequency (4 or 110 Hz), intensity ('to tolerance' or 'strong but comfortable') and stimulation site (segmental--over the distribution of the radial nerve or, extrasegmental--over acupuncture point 'gall bladder 34', or a combination of both segmental and extrasegmental). Pulse duration was fixed at 200 micros. Stimulation was delivered for 30 min and subjects were then monitored for a further 30 min. Mechanical pain threshold (MPT) was measured using a pressure algometer and taken from the first dorsal interosseous muscle of the dominant hand, ipsilateral to the stimulation site. MPT measures were taken, at baseline, and at 10-min intervals for 60 min. Difference scores were analysed using repeated measures and one-way ANOVA and relevant post hoc tests. Low frequency, high intensity, extrasegmental stimulation produced a rapid onset hypoalgesic effect, which increased during the stimulation period (P < 0.0005 control and sham) and was sustained for 30 min post-stimulation (P < 0.0005(control), P = 0.024(sham)). Whilst high frequency, 'strong but comfortable' intensity, segmental stimulation produced comparable hypoalgesic levels during stimulation, this effect was not sustained post-stimulation. Stimulation at a combination of the two sites did not produce any greater hypoalgesic effects. These results may have implications for the clinical use of sensory stimulation.

Acupuncture↗
PubMed1999

Randomized clinical comparison of Healon GV and Viscoat.

PURPOSE: To compare the ability of Healon GV (sodium hyaluronate 1.4%) and Viscoat (sodium chondroitin sulfate 4.0%-sodium hyaluronate 3.0%) to protect the corneal endothelium during endocapsular phacoemulsification and foldable intraocular lens (IOL) implantation. SETTING: A small ophthalmology group practice. METHODS: One hundred forty patients were randomized, 70 per group, in a prospective, partially masked study of cataract surgery using Healon GV or Viscoat. One ophthalmologist performed all surgery. Primary outcome variables were the 2 week postoperative changes in corneal thickness, endothelial cell density, mean endothelial cell size, and endothelial cell hexagonality. Several secondary variables were measured, and an analysis of the statistical power of the study was performed. RESULTS: There were no statistically significant differences between groups in terms of age (P = .856), cataract density (P = .117), preoperative best corrected visual acuity (BCVA) (P = .892), postoperative BCVA (P = .969), amount of viscoelastic material used during surgery (P = .444), amount of irrigating solution used (P = .125), or phacoemulsification time (P = .088). It took longer to remove the Viscoat than the Healon GV (P < .001), and total operating time for the Viscoat group was longer (P < .001). Two weeks after surgery, there were no significant differences between groups in corneal thickness (P = .362), endothelial cell density (P = .351), or mean endothelial cell size (P = .610). However, Viscoat preserved the hexagonal shape of endothelial cells slightly better than Healon GV (P = .043). The study had sufficient power to detect clinically significant differences in corneal thickness, endothelial cell density, and endothelial cell size. CONCLUSIONS: Healon GV and Viscoat were comparable in their ability to protect the corneal endothelium during endocapsular phacoemulsification and foldable IOL implantation. Results may vary, however, if phacoemulsification is performed anterior to the iris plane.

Aged↗
PubMed1999

Familial dilated cardiomyopathy: clinical features in French families.

UNLABELLED: The aims of the study were to analyze the clinical features, the penetrance and the mode of inheritance of 13 French families with dilated cardiomyopathy using diagnostic criteria recently established by a European collaboration. METHODS: Screening consisted of physical examination, ECG and Echo of all the probands first degree relatives (n = 118). Using major Echo criteria [ejection fraction (EF) < 45% or FS < 25% and left ventricular diameter (LVD) > 117% of the predictive value], or combined minor Echo/ECG criteria, relatives were classified as affected, unknown or healthy. RESULTS: (1) Adult affected relatives (n = 31) were identified with major Echo criteria in 74% of cases, and with combined minor Echo/ECG criteria in 26% of cases. (2) In the unknown relatives (n = 21), the most common abnormality was an isolated left ventricular dilation (67%). (3) Mode of inheritance was autosomal dominant (AD) in 11 families and possibly autosomal recessive in two. (4) In AD families, the penetrance was incomplete in adults (72%), age-related (O.R.: 1.3 per 10 years; 95% CI 1.03-1.56) and sex-related [greater in men (87%) than in women (61%), actuarial survival curve: P<0.002]. (5) Mortality related to end stage heart failure was 2.2 times as high as mortality related to sudden death (11% vs. 5%). CONCLUSIONS: (1) In the absence of a specific phenotype of FDC, the characterization of relatives appears more accurate when minor criteria were added. (2) Since high mortality (16%) and incomplete penetrance frequently give rise to small nuclei of clinically affected and alive relatives per family, the accurate model of penetrance that we proposed might be helpful in the future to enhance the statistical power of linkage analysis in this disease.

Adult↗
PubMed2003

Slow progression of white-matter changes.

A three-year follow-up of 273 participants (mean age 60 years) of the Austrian Stroke Prevention Study provides the first information on the rate, clinical predictors, and cognitive consequences of MRI white-matter lesions in elderly individuals without neuropsychiatric disease. Lesion progression was found in 17.9% of individuals over a time period of 3 years. Diastolic blood pressure and early confluent or confluent white-matter hyperintensities at baseline were the only significant predictors of white-matter hyperintensity progression. Lesion progression had no influence on the course of neuropsychologic test performance over the observational period, but the statistical power of this analysis was low.

Aged↗
PubMed2001

Protein structural motif recognition via NMR residual dipolar couplings.

NMR residual dipolar couplings have great potential to provide rapid structural information for proteins in the solution state. This information even at low resolution may be used to advantage in proteomics projects that seek to annotate large numbers of gene products for entire genomes. In this paper, we describe a novel approach to the structural interpretation of dipolar couplings which is based on structural motif pattern recognition, where a predefined gapless structural template for a motif is used to search a set of residual dipolar couplings for good matches. We demonstrate the applicability of the method using synthetic and experimental data. We also provide an analysis of the statistical power of the method and the effects of order tensor frame orientation, motif size, and structural complexity on motif detection. Finally, we discuss remaining problems that must be overcome before the method can be used routinely to identify protein homologies.

Nuclear Magnetic Resonance, Biomolecular↗
PubMed1997

Followup after 11 years--update of mortality results in the Stockholm mammographic screening trial.

Results from several randomised mammography screening trials have shown that it is possible to reduce mortality in breast cancer by mammographic screening at least for women above 50 years of age. The purpose of this article is to present data on mortality in breast cancer in study and control groups of the Stockholm trial after 11 years of followup, to analyse which age group benefits most from screening. In March 1981, 40,318 women in Stockholm, aged 40 through 64 years, entered a randomized trial of breast cancer screening by single view mammography alone, versus no intervention in a control group of 20,000 women. Two screening rounds were performed and the attendance rate was over 80% in the two rounds. During 1986 the control group was invited once to screening. Totally 428 and 217 cases of breast cancer were diagnosed in the study and control groups respectively. After a mean follow-up of 11.4 years a nonsignificant mortality reduction of 26% was observed for the whole study group, with a relative risk (RR) of death in breast cancer of 0.74 (CI(confidence interval) = 0.5-1.1). For women aged 50-64 years a significant 38% mortality reduction was observed with a RR of 0.62 (CI = 0.38-1.0). For women aged 40-49 years no effect on mortality was found, with a RR of death in breast cancer of 1.08 (CI = 0.54-2.17). The breakpoint for benefit in this study seemed to be at 50 years of age when 5-year age groups were analysed, but this tendency is uncertain because of the low statistical power in the analysis of the younger age groups. Long screening intervals, the use of single-view mammography, and the fact that more than 50% of the women in age group 40-49 years were still below 50 years of age when the study was closed, were all facts that could have influenced the results in age group 40-49 years. Larger studies are needed to answer the question whether mammographic screening can be successful in younger age groups.

Adult↗
PubMed2002

Genetic and environmental influences on problematic masturbatory behavior in children: a study of same-sex twins.

Child sexual behavior problems, such as excessive or public masturbation, are often judged to result from environmental stress or trauma. We studied the relative importance of genetic and environmental factors for problematic masturbatory behavior among nonreferred prepubertal children. All twins born in Sweden in 1985-86 were identified from the Swedish Twin Registry. Parents, mainly mothers, completed Child Behavior Checklist (CBCL) ratings (Achenbach, 1991) for 401 monozygotic (MZ) and 248 dizygotic (DZ) same-sex twin pairs (male-male or female-female) at age 7-9 years. Scores of two CBCL items concerning specific sexual behavior problems (Plays with own sex parts in public and Plays with own sex parts too much) were summed and the influence of genetic and environmental factors on variability assessed. The prevalence of problematic child masturbatory behavior was low and associated with other emotional and behavioral problems. The degree of problematic child masturbatory behavior resemblance was higher within MZ twin pairs as compared to DZ same-sex twin pairs. Model fitting indicated that genetic factors substantially influenced the studied behaviors (77%, 95% CI = 9-96%), although family environment also played a role. Our results suggest that hereditary factors should be considered together with stressful experiences such as sexual victimization in the evaluation of elementary school children presenting with problematic masturbatory behaviors. When interpreting the findings, the very brief measure of sexual problem behavior and low statistical power, precluding the analysis of possible coinheritance with other symptoms or disorders, should be borne in mind.

Child↗
PubMed2000

Measurement models for sexual orientation in a community twin sample.

Multivariate structural equation modeling techniques have been applied to examine the causes of individual differences in responses to several items concerning sexual orientation. To minimize potential ascertainment and response biases, the study sample involved a large (N = 4901) community-based cohort of Australian twins aged 18-52 who answered an anonymous questionnaire on sexual behavior and attitudes. The statistical power of the analysis was increased by the availability of multiple measures of sexual orientation (behaviors, attitudes and feelings), providing stronger evidence for the existence of additive genetic influences on this phenotype than in a previous analysis (Bailey et al., 2000). Estimates of the heritability of homosexuality in this sample ranged between 50 and 60% in females but were significantly lower (heritability of approximately 30%) in males.

Adolescent↗
PubMed2001

A family-based strategy to identify genes for diabetic nephropathy.

Diabetic nephropathy (DN) clusters in families and specific ethnic groups, suggesting a genetic basis of disease transmission. Identification of DN susceptibility loci should reveal new therapeutic targets but requires accurate phenotyping. A powerful family-based strategy, which is novel to the pursuit of nephropathy genes in type 2 diabetes, is being used to collect a sample for candidate gene and genome scan analyses. Sib pairs that include DN index cases plus (1) sibs concordant for type 2 diabetes and DN (affected sib pairs [ASPs]) and (2) sibs concordant for type 2 diabetes but discordant for DN (discordant sib pairs [DSPs]) are targeted specifically for recruitment. Type 2 diabetes and DN phenotype criteria for index cases include diabetes onset after 38 years of age, duration 10 years or longer, no initial insulin treatment, diabetic retinopathy, end-stage renal disease (ESRD), and history of nephrotic proteinuria. ESRD patients were screened by questionnaire and medical record review (n = 2114). Of 666 patients with ESRD secondary to DN, 227 had a family history of ESRD, 150 had a living diabetic sib, and 124 families were enrolled. Sixty-five families, with 86 diabetic relative pairs (69 sibs, 17 children), have been completely phenotyped. If nephropathy in diabetic sibs is defined as albuminuria greater than 0.3 g/24 h, 31 ASPs and 26 DSPs (diabetic sib with albuminuria <0.3 g/24 h) were identified. Applying more stringent criteria, only 12 ASPs (sib with diabetes >10 years, diabetic retinopathy, and nephrotic proteinuria) and 9 DSPs (sib with diabetes >10 years and normal urine albumin excretion) were identified. Extrapolating from the number of subjects recruited using stringent phenotyping criteria, nearly 10,000 ESRD patients are required for screening to achieve adequate statistical power for linkage analysis (80% power to detect locus-specific relative risk of 2.2 at a lod score of 3.0). Careful phenotyping requires a large recruitment effort but is necessary to reduce population heterogeneity, a strategy that increases the likelihood of identifying DN loci.

Age of Onset↗
PubMed1991

Guided imagery, hypnosis and recovery from head and neck cancer surgery: an exploratory study.

The value of a brief, preoperative hypnosis experience was explored with a sample of 36 head and neck cancer surgery patients. 15 patients volunteered for the experimental hypnosis intervention. 21 patients who received usual care (no hypnosis) were followed through their hospital charts and were used as a comparison group. Hypnotic intervention and usual care groups were comparable in terms of relevant demographic variables. Postoperative hospitalizations for the hypnotic intervention group were significantly shorter than for the usual care group. Within the hypnotic intervention group, hypnotizability was negatively correlated with surgical complications and there was a trend toward a negative correlation between hypnotizability and blood loss during surgery. Findings suggest that imagery-hypnosis may be prophylactic, benefitting patients by reducing the probability of postoperative complications and thereby keeping hospital stay within the expected range. Recommendations are presented for a controlled, randomized, clinical trial with a sufficiently large sample to provide the opportunity for statistical analysis with appropriate power.

Adult↗
PubMedDate not supplied

Cigarette smoking and the age at menopause.

In a sample of 15,464 apparently healthy Australian women, the mean age at natural menopause of women who smoke ten or more cigarettes a day was 1.3 years lower than that of other women. These distributions were well described by logistic distributions with the same variances. A parallel non-parametric Kaplan-Meier analysis confirmed that heavy smokers reached menopause earlier than other women, and also showed that the women accurately recalled their age at menopause. Logistic regression analyses were used to show that obesity, alcohol intake and regular use of aspirin and other analgesics, sedatives, tranquillizers or anti-depressants did not affect the distribution of the age at natural menopause. The age-specific probability of natural compared with surgically induced menopause was shown to be independent of smoking history and obesity. Logistic regression analysis is a powerful statistical technique for analysing data such as age-specific proportions of still menstrual women. It is easy to apply and interpret, and its aptness for any particular data set is readily assessed.

Adult↗
PubMed2000

Functionalization of hydrocolloids: principal component analysis applied to the study of correlations between parameters describing the consistency of hydrogels.

This work was part of a pure research project on the functionalization of three families of hydrocolloids: cellulose derivatives, carrageenates, and alginates. Principal component analysis (PCA), a powerful statistical method, was used to demonstrate the relations existing among these different parameters that describe the consistency of hydrogels and their spreadability. This approach therefore provides a basis for modeling hydrogel consistency. PCA also afforded a classification of hydrogels that demonstrated the remarkable adhesiveness of very stiff gels based on cellulose derivatives and sodium or potassium alginates. The corresponding semi-fluid gels and all the gels based on carrageenates and mixed sodium-calcium alginates, whatever their spreadability, were found to be very poorly adhesive. Generalized to all the many colloids currently marketed, this approach can be used to set up a databank for the formulation of mucoadhesive excipients.

Adhesiveness↗