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Biomedical subjects

Christopher Drake

Publications and source records attributed to Christopher Drake.

8 recordsLinked to original sources
PubMed2006

Research project: Charleston Bioengineered Kidney Project.

The goal of Charleston Bioengineered Kidney Project is to engineer a functional living human kidney suitable for surgical implantation using principles of directed tissue self-assembly and tissue fusion. This is a multidisciplinary project which incorporates multiple innovative bioengineering technologies and expertise from a broad spectrum of disciplines. The conceptual framework, engineering principles, design, potential cell source as well as the first preliminary data demonstrating the feasibility of the proposed Charleston Bioengineered Kidney Project are outlined. The potential challenges are described. Finally, the experts' opinion about the proposed project is also presented.

Animals↗
PubMed2004

Vulnerability to stress-related sleep disturbance and hyperarousal.

STUDY OBJECTIVES: To determine the presence of a hypothesized trait vulnerability to sleep disturbance and hyperarousal. DESIGN: Polysomnographic assessment of sleep in response to stress during a first night in the laboratory and subsequent physiologic arousal. PARTICIPANTS: One hundred and four individuals (46% men, mean age 40.4 +/- 12.9 years) drawn from a population-based sample. INTERVENTIONS: Individuals were exposed to a first night in the laboratory. MEASUREMENTS AND RESULTS: Participants completed a Likert-scale questionnaire, consisting of 27 items, that assesses sleep disturbance in response to commonly experienced stressful situations. Factor analytic techniques identified a single 9-item factor that was representative of the construct of "stress-related" vulnerability to sleep disturbance. Reliability of the resulting 9-item scale was high (Cronbach's alpha = .83). Individuals with higher scores on this scale, the Ford Insomnia Response to Stress Test (FIRST; median split), had a lower sleep efficiency (P = .001), as well as an increased latency to stage 1 sleep (P = .001) and persistent sleep (P = .002) on the first night of nocturnal polysomnography. Moreover, these high-scoring individuals showed increased arousal as evidenced by an elevated sleep latency on the Multiple Sleep Latency Test compared to individuals with low FIRST scores. Importantly, after controlling for current and past insomnia, the differences between individuals scoring high and low on the FIRST in terms of nocturnal sleep and daytime arousal remained significant. Other stages of sleep (stage 2, slow-wave, and rapid eye movement sleep) were not different between the groups. CONCLUSIONS: These results showing a relationship between FIRST scores and nocturnal polysomnography and Multiple Sleep Latency Test scores have 3 potential implications: (1) the data demonstrate a characteristic that relates to vulnerability to stress-related sleep disturbance as manifested by a first night in the laboratory; (2) the elevated latencies on the Multiple Sleep Latency Test in these individuals, despite significantly disturbed sleep, support the notion of physiologic hyperarousal in these individuals and suggests they may be predisposed to developing chronic primary insomnia; and (3) the vulnerability identified may underlie vulnerability to transient sleep disturbance associated with other sleep-disruptive factors.

Adolescent↗
PubMed2004

Evolution of insomnia: current status and future direction.

Traditional epidemiologic studies of insomnia provide valid but fairly rudimentary information regarding the presence, frequency, duration and evolution of sleep problems. Standardized tools such as validated questionnaires (e.g., Pittsburgh Sleep Quality Index and sleep logs) help assess the presence and severity of sleep problems, while other methods (e.g., SLEEP L system) address insomnia diagnoses. Other instruments (e.g., Structured Clinical Interview for DSM-IV [SCID], Short-Form 36 [SF-36], Epworth Sleepiness Scale [ESS]) provide insights into insomnia consequences and co-morbidities. Sleep laboratory studies using polysomnography (PSG) have also provided useful findings (e.g., relating to sleep apnea and excessive daytime sleepiness) in experimental and population-based patient samples containing subgroups enriched for certain variables under investigation. These methods have significantly increased our knowledge about insomnia. Critically, longitudinal studies are needed to further our understanding of the pathophysiology and morbidity of insomnia, defining roles for risk factors, hyperarousal and co-morbidities and the effects of treatment in long-term disease progression. This review summarizes the current available data on the evolution of insomnia and proposes a model that warrants further research attention and discussion.

Comorbidity↗
PubMed2003

Ethanol and sleep loss: a "dose" comparison of impairing effects.

STUDY OBJECTIVES: Studies to assess the risks associated with sleep loss relative to the well-documented risks of alcohol are limited in number and design. This study compared the "dose"-related sedative, performance-impairing, and amnestic effects of sleep loss to those of ethanol ingestion. DESIGN: Mixed-design experiment with random assignment to a sleep loss (n=12) or ethanol (n=20) group, with each participant assessed under 4 conditions. PARTICIPANTS: Thirty-two healthy normal adult volunteers, aged 21 to 35 years. INTERVENTIONS: In sleep loss, participants had 8, 6, 4, and 0 hours time in bed, producing 0, 2, 4, and 8 hours of sleep loss. For ethanol, participants ingested 0.0 g/kg, 0.3 g/kg, 0.6 g/kg, and 0.9 g/kg ethanol from 8:30 AM to 9:00 AM after 8 hours of time in bed the previous night. Each participant received his or her 4 doses of ethanol or sleep loss in a Latin square design with 3 to 7 days between doses. MEASUREMENTS: All subjects completed the Multiple Sleep Latency Test (MSLT) at 9:30 AM, 11:30 AM, 1:30 PM, 3:30 PM, and 5:30 PM and a performance battery at 10:00 AM, 12:00 NOON, 2:00 PM, and 4:00 PM consisting of memory, psychomotor vigilance, and divided attention tests. RESULTS: Ethanol and sleep loss reduced the average daily sleep latency on the MSLT, both as a linear function of dose, with sleep loss in hours being 2.7 times more potent than ethanol in grams per kilogram. Ethanol and sleep loss also slowed reaction time on the psychomotor vigilance test in a linear dose-related function with the 2 being equipotent in their impairing effect. On the divided attention test, tracking deviations were increased by both ethanol and sleep loss in an equipotent and linear dose-related function. Memory recall was reduced in a linear dose-related function by both ethanol and sleep loss with ethanol being slightly more potent. Finally, sleep loss doses produced a linear decrease in self-rated quality of performance, while only at the highest ethanol dose was performance rated as poorer. CONCLUSIONS: At the studied doses, sleep loss was more potent than ethanol in its sedative effects but comparable in effects on psychomotor performance. Ethanol produced greater memory deficits, and subjects were less aware of their overall performance impairment.

Adult↗
PubMed2003

The pediatric daytime sleepiness scale (PDSS): sleep habits and school outcomes in middle-school children.

STUDY OBJECTIVES: To develop a measure of daytime sleepiness suitable for middle-school children and examine the relationship between daytime sleepiness and school-related outcomes. DESIGN: Self-report questionnaire. PARTICIPANTS: Four hundred fifty, 11- to 15-year-old students, from grades 6, 7, and 8 of a public middle school in Dayton, Ohio. MEASUREMENTS AND RESULTS: A pediatric daytime sleepiness questionnaire was developed using factor analysis of questions regarding sleep-related behaviors. Results of the sleepiness questionnaire were then compared across other variables, including daily sleep patterns, school achievement, mood, and extracurricular activities. RESULTS: Factor analysis on the 13 questions related to daytime sleepiness yielded 1 primary factor ("pediatric daytime sleepiness"; 32% of variance). Only items with factor loadings above .4 were included in the final sleepiness scale. Internal consistency (Chronbach's alpha) for the final 8-item scale was .80. Separate one-way analyses of variance and trend analyses were performed comparing pediatric daytime sleepiness scores at the 5 different levels of total sleep time and academic achievement. Participants who reported low school achievement, high rates of absenteeism, low school enjoyment, low total sleep time, and frequent illness reported significantly higher levels of daytime sleepiness compared to children with better school-related outcomes. CONCLUSIONS: The self-report scale developed in the present work is suitable for middle-school-age children and may be useful in future research given its ease of administration and robust psychometric properties. Daytime sleepiness is related to reduced educational achievement and other negative school-related outcomes.

Adolescent↗
PubMed2002

Substance use for insomnia in Metropolitan Detroit.

OBJECTIVE: People with insomnia are not typically treated medically for their insomnia. Studies have reported approximately 30% of insomniacs self-medicate with alcohol or over-the-counter (OTC) medications. This study was done to identify determinants and risks of different insomnia therapeutics. METHODS: A random-digit-dial, computer-assisted survey of a representative sample of adults in Metropolitan Detroit, aged 18-65 years, is being conducted. A sample of all respondents over an 18-month period was collected (n=1324) with a 68% response rate. Exclusive past-year use of alcohol for sleep was reported by 10% (n=132), prescription medications by 8% (n=108), and OTC medications by 10% (n=135). Five percent used both alcohol and sleep medications. The three exclusive-use groups formed the comparison groups of the study. RESULTS: The prescription drug group used medications for more consecutive nights and for more total nights than the alcohol and OTC users. Alcohol users were predominantly male, while OTC and prescription drug users were predominantly female. Alcohol users were more likely to be single than the others, and prescription drug users were older than the others. Prescription drug users had more severe insomnia and had greater disability, neuroticism, and daytime fatigue than the others. In contrast, the alcohol users had greater daytime sleepiness than the others. CONCLUSIONS: In Metropolitan Detroit, insomniacs receiving medical treatment have more severe insomnia and greater disability than those who self-treat. However, while the insomnia of those self-treating is less severe, it is still associated with some risks.

Adolescent↗
PubMed2002

A comparison of different sample matrices for evaluating functional sensitivity, imprecision and dilution linearity of the Abbott ARCHITECT i2000 TSH assay.

Important performance characteristics for any thyroid-stimulating hormone (TSH) assay include low-end sensitivity, precision across a wide dynamic range, and linear specimen dilution. Laboratories often characterize the performance of their TSH assay using many different sample matrices (e.g. native human serum, synthetic buffer, processed human serum, etc.). However, this can lead to possible confusion as the relationships between sample matrix and assay performance are often poorly understood. The purpose of our study was to evaluate the performance of the ARCHITECT i2000 TSH assay using a variety of different sample matrices. Functional sensitivity was found to be essentially equivalent in both hyperthyroid patient sera (0.0035 microIU/ml) and TSH affinity-stripped (0.0038 microIU/ml) sample matrices. Assay imprecision was also independent of sample matrix, with total imprecision < or = 5.3% for both synthetic buffer and serum matrices. Similarly, specimens were found to dilute linearly over a wide range in both serum and synthetic buffer matrices. We conclude that the i2000 TSH assay measures TSH similarly in a variety of sample matrices. This is an important design feature for this immunoassay which provides assurance that analytical performance assessed with matrices other than unprocessed human serum are representative of assay performance seen with patient specimens.

Calibration↗