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Biomedical subjects

Jennifer Thomas

Publications and source records attributed to Jennifer Thomas.

8 recordsLinked to original sources
PubMed2006

Evaluating masking in a randomized, double-masked clinical trial in children with myopia.

PURPOSES: The purposes of this study were to evaluate the success of masking in the Correction of Myopia Evaluation Trial (COMET), a study designed as a randomized, double-masked clinical trial comparing the effect of progressive addition lenses (PALs) with single-vision lenses (SVLs) in slowing myopia progression among children and to investigate the impact of unmasking on the treatment effect. METHODS: The success of masking of children and parents was assessed by questionnaires administered after the clinical trial results were reported and before families were informed of their child's lens assignment. Children and parents who correctly guessed their assignment with absolute or "pretty sure" certainty were considered as unmasked. The role of children's age, gender, and ethnicity in unmasking was evaluated using logistic regression. The impact of unmasking on the treatment effect at 3 years was investigated using analysis of variance. The success of masking of the study optometrists was assessed by data collected at the child's follow-up visits. RESULTS: Overall 93% (436 of 469) of the COMET children responded to the questions about lens assignment and certainty. Thirty-seven percent (163 of 436) of children met the criteria for being unmasked with similar results from the parents. The majority (91%) of the 163 "unmasked" children reported that their glasses were the main reason for lens identification. Although children 10 to 11 years at baseline became unmasked more often than did children 6 to 9 years (44% vs. 31%, p = 0.01), there was no difference between boys and girls becoming unmasked (p = 0.2). The treatment effect did not differ between the masked and unmasked children (p = 0.69). The study optometrists became unmasked for five children over the course of 3-year follow up. CONCLUSIONS: Masking was successfully maintained for the study optometrists and the majority (63%) of COMET children. Although some children were able to identify their lens assignment, the primary study outcome was not affected by unmasking.

Child↗
PubMed2005

Cardiac PPARalpha expression in patients with dilated cardiomyopathy.

BACKGROUND: The peroxisome proliferator-activated receptor alpha (PPARalpha) is a central regulator of myocardial fatty acid (FA) metabolism implicated in the pathogenesis of heart failure. AIMS: To characterize PPARalpha regulation in human dilated cardiomyopathy (DCM), we studied the expression of cardiac PPARalpha, cardiac carnitine palmitoyl-transferase I (CPT-1), a major PPARalpha target gene, and of the cardiac glucose transporter GLUT-4 in patients with DCM. METHODS: Left ventricular biopsies were taken from patients with DCM (n=16) and control subjects (n=15), and mRNA expression was quantitated using real-time PCR (SYBR((R))Green) and protein expression was measured by Western immunoblotting. RESULTS: Left ventricular PPARalpha mRNA levels were significantly increased in the DCM group compared to the control group (136+/-25.4% vs. control, p<0.01). Consistently, DCM patients had a significantly higher cardiac CPT-1 mRNA expression (147+/-51% vs. control, p<0.05) compared to the control group. Cardiac GLUT-4 expression was similar in both groups. CONCLUSION: Elevated cardiac PPARalpha levels followed by an induction of cardiac CPT-1 expression may result in increased fatty acid metabolism for cardiac energy production in DCM, suggesting a specific cardiac metabolic program in human DCM compared to other types of cardiomyopathy.

Adolescent↗
PubMed2005

Effects of milrinone versus epinephrine on left ventricular relaxation after cardiopulmonary bypass following myocardial revascularization: assessment by color m-mode and tissue Doppler.

OBJECTIVE: The purpose of this study was to evaluate the left ventricular lusitropic effects of epinephrine versus milrinone after cardiopulmonary bypass. DESIGN: Prospective randomized study. SETTING: Single institution, university teaching hospital. PARTICIPANTS: Adult patients undergoing coronary artery bypass grafting under cardiopulmonary bypass. INTERVENTIONS: After separation from cardiopulmonary bypass, patients were randomized to receive intravenous epinephrine by continuous infusion (0.03 microg/kg/min) or milrinone (50 microg/kg followed by 0.5 microg/kg/min). Transesophageal echocardiographic evaluation of left ventricular diastolic function, with emphasis on relaxation, was performed before and after bypass and after the administration of either epinephrine or milrinone. MEASUREMENTS AND MAIN RESULTS: Measurements included pulse-wave Doppler analysis of mitral inflow and pulmonary vein and left ventricular outflow tract velocities. Left ventricular inflow velocity of propagation measured with color M-mode and tissue Doppler assessment of early mitral annulus velocity were used to evaluate left ventricular relaxation. Values of velocity of propagation and mitral annulus velocity improved significantly after bypass, suggesting improved relaxation. The administration of either epinephrine or milrinone did not result in further improvement in left ventricular relaxation. CONCLUSIONS: After cardiopulmonary bypass, left ventricular relaxation was significantly improved. Neither epinephrine nor milrinone exhibited favorable lusitropic effects after bypass.

Aged↗
PubMed2005

Reasons for high retention in pediatric clinical trials: comparison of participant and staff responses in the Correction of Myopia Evaluation Trial.

BACKGROUND: The Correction of Myopia Evaluation Trial (COMET), a randomized, multicenter clinical trial of myopia progression in children, had an exceptionally high retention rate of 98.5% (462/469) at three years of follow-up. The present investigation was designed to evaluate and compare the reasons for COMET's high retention rate according to participating families and clinical center staff. METHODS: Families (n = 411) and staff (n = 35) completed a confidential 19-item questionnaire by indicating families' levels of preference for each item, and rating its importance in keeping families in the study. The questionnaire evaluated study features in four categories: staff characteristics, operational aspects, specific study elements, and incentives. RESULTS: Results showed that most families viewed the study very favorably. Features that appealed to 90% or more families and promoted continued study participation included staff attributes such as friendliness, responsiveness and encouragement, and aspects pertaining to standard of care such as completeness of eye exam, quality of eye care and free eyeglasses. Compared to families, staff tended to underestimate the importance of the following features for retention: seeing the same staff at each visit, appointment reminders, center location, newsletters, commitment to the study, being part of a nationwide study, length of the study, association with a college of optometry, completeness of eye exam, and eye drops (p < 0.05 by chi-square analyses). However, staff responses also revealed less preferred components of the study protocol (e.g., eye drops), to which families might have been reluctant to respond unfavorably. CONCLUSIONS: Our findings highlight the importance of intangible factors such as staff attributes and participants' study commitment in maintaining high retention rates, and the usefulness of surveying both families and staff.

Child↗
PubMed2005

Novel spanish translators for acute care nurses and physicians: usefulness and effect on practitioners' stress.

BACKGROUND: Language barriers are significant impediments to providing quality health care, and increased stress levels among nurses and physicians are associated with these barriers. However, little evidence supports the usefulness of a translation tool specific to health care. OBJECTIVES: To evaluate the effectiveness of a novel English-Spanish translator designed specifically for nurses and physicians. The hypothesis was that the translator would be useful and that use of the translator would decrease stress levels among nurses and physicians caring for Spanish-speaking patients. METHODS: Novel English-Spanish translators were developed entirely on the basis of input from critical care nurses and physicians. After 7 months of use, users completed surveys. Usefulness of the translator and stress levels among users were reported. RESULTS: A total of 60% of nurses (n=32) and 71% (n=25) of physicians responded to the survey. A total of 96% of physicians and 97% of nurses considered the language barrier an impediment to delivering quality care. Nurses reported significantly more stress reduction than did physicians (P=.01). Most nurses and physicians had used the translator during the survey period. Overall, 91% of nurses and 72% of physicians found that the translator met their needs at the bedside some, most, or all of the time. All nurses thought that they most likely would use the translator in the future. CONCLUSIONS: The translator was useful for most critical care nurses and physicians surveyed. Health care providers, especially nurses, experienced decreased stress levels when they used the translator.

Communication Barriers↗
PubMed2004

Timing errors in auditory event-related potentials.

Electronic problems of electroencephalographic (EEG) system may occur in even the best-managed laboratories. Timing error may happen in the coupling of computers from various manufactures, resulting in the misalignment of event markers that signal the onset of stimuli. In one system, an impedance check desynchronized a computer and thus caused misalignment of events in EEG signals. Thus, the aim of this study was to develop a method to identify and correct such timing errors that contaminated 114 raw data of EEG/auditory event-related potentials (ERPs) recorded in one of our longitudinal studies. A two-step procedure was introduced in the correction of timing errors. First, the time delay was roughly estimated by identifying a P150 component in two ERP blocks. Second, a small phase-locked positive wave was identified for fine estimation. Reliability within and among evaluators was examined using ERP data with simulated timing errors. Concordant results were obtained in 104 (91.2%) of the 114 raw EEG/ERP data sets. Our results showed that the method presented here is reliable and can be used for correcting timing errors without introduction of experimenter bias.

Acoustic Stimulation↗
PubMed2002

Effects of dietary sodium and genetic background on angiotensinogen and Renin in mouse.

Elements of a renin-angiotensin system expressed along the entire nephron, including angiotensinogen secreted by proximal tubule and renin expressed in connecting tubule, may participate in the regulation of sodium reabsorption at multiple sites of the nephron. The response of this tubular renin-angiotensin system to stepwise changes in dietary sodium was investigated in 2 mouse strains, the sodium-sensitive inbred C57BL/6 and the sodium-resistant CD1 outbred. Plasma angiotensinogen was not affected by sodium regimen, whereas plasma renin increased 2-fold under low sodium. In both strains, the variation in urinary parameters did not parallel the changes observed in plasma. Angiotensinogen and renin excretion were significantly higher under high sodium than under low sodium. Water deprivation, by contrast, induced significant activation in the tubular expression of angiotensinogen and renin. C57BL/6 exhibited significantly higher urinary excretion of angiotensinogen than did CD1 animals under both conditions of sodium intake. The extent to which these urinary parameters reflect systemic or tubular responses to challenges of sodium homeostasis may depend on the relative contribution of sodium restriction and volume depletion.

Aldosterone↗