Biomedical subjects

Sam Lee

Publications and source records attributed to Sam Lee.

3 recordsLinked to original sources

PubMed2006

Nasal dilator strip therapy for chronic sleep-maintenance insomnia and symptoms of sleep-disordered breathing: a randomized controlled trial.

To test the impact of nasal dilator strips (NDSs) on insomnia severity, sleep-disordered breathing (SDB) symptoms, sleep quality, and quality of life. Randomized, controlled trial of 4 weeks' duration. Community sample of nonobese, adults with a primary sleep complaint of chronic sleep-maintenance insomnia and mild to moderate SDB symptoms (treatment, n=42; control, n=38). Primary outcomes were four validated scales: Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), Functional Outcomes of Sleep Questionnaire (FOSQ), and Quality of Life Enjoyment and Satisfaction Questionnaire (QLESQ). Secondary outcomes were sleep indices, nonrestorative sleep ratings, and SDB symptoms, assessed retrospectively and prospectively. Both groups received nonspecific education about sleep disorders. Treatment group also received a brief SDB education and nasal strip instructions. At 4 weeks' follow-up, the treatment group demonstrated significant (p=.0001), large improvements in ISI and PSQI (mean Cohen's d=1.18) and significant (p<.02), medium-sized improvements in FOSQ and QLESQ (mean d=0.51) compared to small, nonsignificant changes in control group (Cohen's d range=0.36-0.09). Treatment group change scores among all four primary variables were significantly correlated (mean r=0.50, p=0.01). Secondary prospective and retrospective outcomes showed medium to large improvements in treatment compared to controls for sleep indices (mean d=0.52 vs 0.28), nonrestorative sleep ratings (mean d=0.69 vs 0.11), and sleep breathing symptoms (mean d=0.47 vs 0.09). Significance was obtained for prospective sleep indices (p=0.01), retrospective, and prospective nonrestorative sleep ratings (p=0.003, <0.05), and retrospective sleep breathing symptoms (p=0.03). SDB education and NDSs demonstrated therapeutic efficacy in a select sample of insomnia patients with SDB symptoms. Replication of results requires placebo controls and objectively confirmed SDB cases.

Chronic Disease↗

PubMed2005

Neural mechanisms underlying probabilistic category learning in normal aging.

Probabilistic category learning engages neural circuitry that includes the prefrontal cortex and caudate nucleus, two regions that show prominent changes with normal aging. However, the specific contributions of these brain regions are uncertain, and the effects of normal aging have not been examined previously in probabilistic category learning. In the present study, using a blood oxygenation level-dependent functional magnetic resonance imaging block design, 18 healthy young adults (mean age, 25.5 +/- 2.6 years) and 15 older adults (mean age, 67.1 +/- 5.3 years) were assessed on the probabilistic category learning "weather prediction" test. Whole-brain functional images acquired using a 1.5T scanner (General Electric, Milwaukee, WI) with gradient echo, echo planar imaging (3/1 mm; repetition time, 3000 ms; echo time, 50 ms) were analyzed using second-level random-effects procedures [SPM99 (Statistical Parametric Mapping)]. Young and older adults displayed equivalent probabilistic category learning curves, used similar strategies, and activated analogous neural networks, including the prefrontal and parietal cortices and the caudate nucleus. However, the extent of caudate and prefrontal activation was less and parietal activation was greater in older participants. The percentage correct and reaction time were mainly positively correlated with caudate and prefrontal activation in young individuals but positively correlated with prefrontal and parietal cortices in older individuals. Differential activation within a circumscribed neural network in the context of equivalent learning suggests that some brain regions, such as the parietal cortices, may provide a compensatory mechanism for healthy older adults in the context of deficient prefrontal cortex and caudate nuclei responses.

Adult↗

PubMed2005

Negative control of keratinocyte differentiation by Rho/CRIK signaling coupled with up-regulation of KyoT1/2 (FHL1) expression.

Rho GTPases integrate control of cell structure and adhesion with downstream signaling events. In keratinocytes, RhoA is activated at early times of differentiation and plays an essential function in establishment of cell-cell adhesion. We report here that, surprisingly, Rho signaling suppresses downstream gene expression events associated with differentiation. Similar inhibitory effects are exerted by a specific Rho effector, CRIK (Citron kinase), which is selectively down-modulated with differentiation, thereby allowing the normal process to occur. The suppressing function of Rho/CRIK on differentiation is associated with induction of KyoT1/2, a LIM domain protein gene implicated in integrin-mediated processes and/or Notch signaling. Like activated Rho and CRIK, elevated KyoT1/2 expression suppresses differentiation. Thus, Rho signaling exerts an unexpectedly complex role in keratinocyte differentiation, which is coupled with induction of KyoT1/2, a LIM domain protein gene with a potentially important role in control of cell self renewal.

Adenoviridae↗