T R Bidwell | PubMed Health

PubMed1994

Smoking as a risk factor for sleep-disordered breathing.

BACKGROUND: Recent evidence indicates that the prevalence of sleep-disordered breathing is remarkably high (24% for men and 9% for women) and that the public health burden attributable to sleep-disordered breathing is substantial. This investigation examines current and former cigarette smoking as potential risk factors for sleep-disordered breathing. METHODS: Data were from 811 adults enrolled in the University of Wisconsin Sleep Cohort Study, Madison. The Sleep Cohort Study is a longitudinal, epidemiologic study that uses nocturnal polysomnography to investigate sleep-disordered breathing and other disorders of sleep. The presence and severity of sleep-disordered breathing was quantified by the frequency of apneas and hypopneas per hour of sleep. RESULTS: Logistic regression analyses were used to control for potential confounding factors. Compared with never smokers, current smokers had a significantly greater risk of snoring (odds ratio, 2.29) and of moderate or worse sleep-disordered breathing (odds ratio, 4.44). Heavy smokers (> or = 40 cigarettes per day) had the greatest risk of mild sleep-disordered breathing (odds ratio, 6.74) and of moderate or worse sleep-disordered breathing (odds ratio, 40.47). Former smoking was unrelated to snoring and sleep-disordered breathing after adjustment for confounders. CONCLUSIONS: Current cigarette smokers are at greater risk for sleep-disordered breathing than are never smokers. Heavy smokers have the greatest risk while former smokers are not at increased risk for sleep-disordered breathing. Thus, smoking cessation should be considered in the treatment and prevention of sleep-disordered breathing.

Adult↗

PubMed1992

Comparison of alternative diphasic lactation curve models under bovine somatotropin administration.

The multiphasic logistic function has recently been proposed as a model for lactation curves in dairy cattle. The applicability of several forms of this function was examined under three levels of recombinant bST administration beginning 100 d postpartum. Lactation curve models were fit to mean daily yields for each of the treatment groups and a control group. The traditional diphasic function was unable to model adequately the steep ascent and early peak in daily milk yield occurring immediately after calving in both treatment and control groups. The early portion of the lactation was more appropriately modeled using a diphasic function with a power transformation of time in the first phase, such that this phase became asymmetric. This modified diphasic function also resulted in smaller residuals and less autocorrelation than the triphasic function, which was used as a reference model, when both models were applied to the control group data. The increase in daily milk yield because of bST administration was modeled by the addition of a term consisting of a rising exponential function. Such a model may be useful for examining dosage effects in long-term bST studies in which injections begin in midlactation or later. Time series procedures reduced autocorrelation among residuals in both the control and treatment groups, and such models could be useful for removing autocorrelation in lactation curve applications that involve daily or weekly yield observations.

Animals↗