Biomedical subjects

Edward J Bedrick

Publications and source records attributed to Edward J Bedrick.

11 recordsLinked to original sources

PubMed2006

Changing relationship of blood pressure with mortality over time among hemodialysis patients.

High BP is a major risk factor for atherosclerotic cardiovascular disease mortality in the general population. Surprising, studies that have been conducted among hemodialysis (HD) patients have yielded conflicting data on the relationship between BP and mortality. This study explores two hypotheses among HD patients: (1) The relationship between BP and mortality changes over time, and (2) mild to moderate hypertension is well tolerated. Incident HD patients who were treated at Dialysis Clinic Inc. facilities between 1993 and 2003 were studied. Primary end points were atherosclerotic cardiovascular disease and all-cause mortality. The relationship between BP and mortality was analyzed in two sets of Cox proportional hazards models. Model-B explored the relationship between baseline BP and mortality in sequential time periods. Model-TV assessed the relationship between BP, treated as time-varying, and mortality. The study sample (n = 16,959) was similar in characteristics to the United States Renal Data Systems population, although black patients were slightly overrepresented. Model-B demonstrated that the relationship between baseline BP and mortality changes over time. Low systolic BP (<120 mmHg) was associated with increased mortality in years 1 and 2. High systolic BP (> or =150 mmHg) was associated with increased mortality among patients who survived > or =3 yr. Low pulse pressure was associated with increased mortality. Model-TV demonstrated that mild to moderate systolic hypertension may be relatively well tolerated. In conclusion, the relationship between baseline BP and mortality changes over time. Mild to moderate systolic hypertension was associated with only modest increases in mortality.

Adult↗

PubMed2005

Effect of cigarette smoke on autoimmunity in murine and human systemic lupus erythematosus.

Several studies have found that smoking cigarettes is a risk factor for systemic lupus erythematosus (SLE). To examine this issue in a mouse model, we subjected pre-autoimmune MRL-lpr/lpr mice for 4 weeks to cigarette smoke to provide standardized smoke effluents equivalent to moderate or to heavy smoking habits for people. The spontaneous production of IgG anti-chromatin but not IgM anti-chromatin, anti-denatured DNA, or rheumatoid factor antibodies was lower in mice exposed to 250 mg/m3 particulates from mainstream smoke, and this suppression of autoimmunity was sustained for 8 weeks (p < 0.02). In contrast to control mice anti-chromatin activity in smoke-exposed mice began to increase in 16-week-old mice, reaching levels at 6 months that were two- to three-fold higher than controls for IgG (p < 0.03) and 10-fold higher for IgM (p < 0.001). There was no significant effect on total IgG or IgM. In newly diagnosed SLE patients, smoking was negatively correlated with IgG anti-DNA antibodies (p < 0.03). However, of nine patients who discontinued smoking prior to diagnosis, eight had elevated IgG anti-DNA compared to 29/79 never smokers and 9/31 smokers (p < 0.01 compared to former smokers). Inhaled cigarette smoke appears to have a long-lasting immunosuppressive effect on T-cell-dependent autoimmune responses, although autoantibodies increase to supra-elevated levels after the suppressive effect has abated.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Nutrient and organic carbon trends and patterns in the upper Rio Grande, 1975-1999.

Nutrient patterns and trends were analyzed using USGS water quality data collected from 1975 to 1999 along the uppermost 600 km of the Rio Grande in Colorado and New Mexico. Data on discharge, pH, organic carbon (total), N-NH(4+)+organic N (total), NH4+ (dissolved), N-NO(2-)+N-NO3- (dissolved), phosphorus (total), and P-orthophosphate (dissolved) came from six USGS stations--Lobatos, Taos Junction, Otowi, San Felipe, Isleta and Bernardo--ranging from the Colorado-New Mexico border to about 80 km below Albuquerque, NM. Kendall's S and Seasonal Kendall's S' were used to measure trend, and ANOVA and Tukey's multiple comparison test were used to analyze spatial differences between stations. Temporal trend analyses show widespread decreases in N and P concentrations at most stations, likely due to improvements in sewage treatment and dilution from increasing discharge. N-NO(2-)+N-NO3- (dissolved) and total nitrate load increases at Isleta and Bernardo, likely due to improved nitrification in sewage treatment and to increasing human population. Spatial analyses show large increases for most parameters at Isleta. All parameters show decreases again at Bernardo, about 50 km downstream from Isleta, except for N-NO(2-)+N-NO3- (dissolved), which continues to increase. Urbanization in the Albuquerque area significantly impacts downstream river nutrient levels.

Colorado↗

PubMed2005

Diagnostics for the exponential normal growth curve model.

The exponential normal regression model provides a flexible parametric approach to constructing growth charts or centile curves. We develop diagnostics for this model, with a special emphasis towards assessing the impact of individual cases on estimated centile curves. We also propose a standardized score residual that assesses the fit of individual cases to the location, scale, and skewness functions, respectively. An application of the proposed diagnostics is presented.

Anthropometry↗

PubMed2005

The prehospital 12-lead electrocardiogram's effect on time to initiation of reperfusion therapy: a systematic review and meta-analysis of existing literature.

The prehospital electrocardiogram (ECG) is becoming the standard of care of suspected cardiac chest pain. We evaluated the evidence regarding the prehospital ECG and sought to quantify the reduction in time to reperfusion therapy attributable to the prehospital ECG. We conducted a systematic review and analyzed studies that were conducted in emergency medical systems relevant to providers in the United States. The papers were limited to studies that reported original data that compared prehospital ECG to no prehospital ECG groups. Four studies containing 99 patients met the inclusion criteria. A meta-analysis of these studies revealed a difference of 24.7 (95% confidence interval, 16.7-32.7) minutes. Providers now have a quantified value of the prehospital ECG based on the best published evidence. In addition, this search showed a relatively low quality and quantity of research on the prehospital ECG.

Confidence Intervals↗

PubMed2005

Using the Bivariate Dale Model to jointly estimate predictors of frequency and quantity of alcohol use.

OBJECTIVE: This study demonstrates the usefulness of the Bivariate Dale Model (BDM) as a method for estimating the relationship between risk factors and the quantity and frequency of alcohol use, as well as the degree of association between these highly correlated drinking measures. METHOD: The BDM is used to evaluate childhood sexual abuse, along with age and gender, as risk factors for the quantity and frequency of beer consumption in a sample of driving-while-intoxicated (DWI) offenders (N = 1,964; 1,612 men). The BDM allows one to estimate the relative odds of drinking up to each level of ordinal-scaled quantity and frequency of alcohol use, as well as model the degree of association between quantity and frequency of alcohol consumption as a function of covariates. RESULTS: Individuals who experienced childhood sexual abuse have increased risks of higher quantity and frequency of beer consumption. History of childhood sexual abuse has a greater effect on women, causing them to drink higher quantities of beer per drinking occasion. CONCLUSIONS: The BDM is a useful method for evaluating predictors of the quantity-frequency of alcohol consumption. SAS macrocode for fitting the BDM model is provided.

Adult↗

PubMed2003

A mixture model for bovine abortion and foetal survival.

The effect of spontaneous abortion on the dairy industry is substantial, costing the industry on the order of US dollars 200 million per year in California alone. We analyse data from a cohort study of nine dairy herds in Central California. A key feature of the analysis is the observation that only a relatively small proportion of cows will abort (around 10;15 per cent), so that it is inappropriate to analyse the time-to-abortion (TTA) data as if it were standard censored survival data, with cows that fail to abort by the end of the study treated as censored observations. We thus broaden the scope to consider the analysis of foetal lifetime distribution (FLD) data for the cows, with the dual goals of characterizing the effects of various risk factors on (i). the likelihood of abortion and, conditional on abortion status, on (ii). the risk of early versus late abortion. A single model is developed to accomplish both goals with two sets of specific herd effects modelled as random effects. Because multimodal foetal hazard functions are expected for the TTA data, both a parametric mixture model and a non-parametric model are developed. Furthermore, the two sets of analyses are linked because of anticipated dependence between the random herd effects. All modelling and inferences are accomplished using modern Bayesian methods.

Abortion, Veterinary↗

PubMed2003

Reproducibility of 1H-MRS measurements in schizophrenic patients.

The reproducibility of single-voxel spectroscopic measures in a stable schizophrenic patient population is reported. Spectra acquired 1 week apart, in the left frontal white matter and left caudate nucleus of 12 patients, were analyzed using both frequency and time-domain techniques. No significant change in mean concentrations for N-acetylaspartate (NAA), choline (Cho), and creatine (Cre) were found between sessions. Variation from scan to scan was low for the left frontal white matter, with coefficients of variation (CV) < 5% for all three metabolites. NAA measures from the left caudate nucleus had similar reproducibility (CV = 5%), but Cho and Cre were poorer by comparison (CV = 16-18%). The two methods used for spectral analyses produced similar results, indicating that both techniques are appropriate. These results extend previous studies of healthy, normal subjects, and establish that it is possible to obtain reliable measures of brain metabolites in clinical populations.

Adult↗

PubMed2003

Ethnic differences at risk for gestational trophoblastic disease in New Mexico: A 25-year population-based study.

OBJECTIVE: The purpose of this study was to compare gestational trophoblastic disease incidence rates with the use of population-based data. STUDY DESIGN: All incident cases between 1973 and 1997 and live birth, pregnancy, and women at risk were tabulated with the use of data that were derived from the New Mexico Tumor Registry and Vital Records and Health Statistics Annual Reports. Statistical methods included trends analyses, odds ratios, and Poisson regression. RESULTS: Of 939 total cases, 312 non-Hispanic white women, 399 Hispanic white women, 201 American Indian women, and 27 other women were affected. Age-adjusted incidence rates were significantly higher for American Indian women (11.16%) compared with non-Hispanic (3.57%) or Hispanic white women (5.32%); the probability value was <.001. When live birth (1:438 women) and pregnancy (1:486 women) denominators were considered, American Indian women alone were at increased risk, and the ratio increased by 56% over 25 years. American Indian women were also at increased risk for partial mole (relative risk, 4.03; 95% CI, 2.57-6.31), invasive mole (relative risk, 26.7; 95% CI, 7.81-93.14), and choriocarcinoma (relative risk, 6.29; 95% CI, 1.81-22.66) variants. CONCLUSION: American Indians are at increased risk relative to the other predominant ethnic groups in New Mexico. Age-adjusted standardization provided a reproducible measurement that may be applicable across other registries.

Adolescent↗

PubMed2002

Predictive influence in the accelerated failure time model.

We develop case deletion diagnostics for prediction of future observations in the accelerated failure time model. We view prediction to be an important inferential goal in a survival analysis and thus it is important to identify whether particular observations may be influencing the quality of predictions. We use the Kullback-Leibler divergence as a measure of the discrepancy between the estimated probability distributions for the full and the case-deleted samples. In particular, we focus on the effect of case deletion on estimated survival curves but where we regard the survival curve estimate as a vehicle for prediction. We also develop a diagnostic for assessing the effect of case deletion on inferences for the median time to failure. The estimated median can be used with both predictive and estimative purposes in mind. We also discuss the relationship between our suggested measures and the corresponding Cook distance measure, which was designed with the goal of assessing estimative influence. Several applications of the proposed diagnostics are presented.

Journal Article↗

PubMedDate not supplied

Midwifery care measures in the second stage of labor and reduction of genital tract trauma at birth: a randomized trial.

Genital tract trauma after spontaneous vaginal childbirth is common, and evidence-based prevention measures have not been identified beyond minimizing the use of episiotomy. This study randomized 1211 healthy women in midwifery care at the University of New Mexico teaching hospital to 1 of 3 care measures late in the second stage of labor: 1) warm compresses to the perineal area, 2) massage with lubricant, or 3) no touching of the perineum until crowning of the infant's head. The purpose was to assess whether any of these measures was associated with lower levels of obstetric trauma. After each birth, the clinical midwife recorded demographic, clinical care, and outcome data, including the location and extent of any genital tract trauma. The frequency distribution of genital tract trauma was equal in all three groups. Individual women and their clinicians should decide whether to use these techniques on the basis of maternal comfort and other considerations.

Adult↗