Use of the modified Delphi technique to identify and rate home injury hazard risks and prevention methods for young children.

OBJECTIVE: For children aged 1-5 years, the authors used the Delphi method to determine (1) the most important injury hazards in each area of the home; (2) the most important injury prevention behaviors; and (3) feasible and efficacious safety devices and behaviors to reduce injury risks. DESIGN: The authors used a modified Delphi method to prioritize home injury hazards for children 1-5 years of age. The Delphi method is an indirect, anonymous, iterative process aimed at achieving consensus among experts; in this study, the authors queried key informants electronically. Thirty four key informants, primarily from the United States, participated in at least one of the three rounds of questionnaires. Responses were submitted by email or fax. Participants identified, rated, and ranked home injury hazards and prevention methods. RESULTS: The overall response rate for each survey ranged from 82% to 97%. Initially, 330 unique hazards and prevention behaviors/devices were identified in seven areas of the home. The 126 home injury hazards were rated based on frequency, severity, and preventability of injury; and the 204 behaviors and devices were rated by efficacy and feasibility. These experts rated firearms and pools as the most significant hazards, and smoke alarms and safe water temperature as the most important preventions. CONCLUSIONS: The modified Delphi method of consensus was useful to prioritize home injury hazards and prevention methods for children under the age of 6 years.

Neurocirculatory consequences of intermittent asphyxia in humans.

We examined the neurocirculatory and ventilatory responses to intermittent asphyxia (arterial O(2) saturation = 79-85%, end-tidal PCO(2) =3-5 Torr above eupnea) in seven healthy humans during wakefulness. The intermittent asphyxia intervention consisted of 20-s asphyxic exposures alternating with 40-s periods of room-air breathing for a total of 20 min. Minute ventilation increased during the intermittent asphyxia period (14.2 +/- 2.0 l/min in the final 5 min of asphyxia vs. 7.5 +/- 0.4 l/min in baseline) but returned to the baseline level within 2 min after completion of the series of asphyxic exposures. Muscle sympathetic nerve activity increased progressively, reaching 175 +/- 12% of baseline in the final 5 min of the intervention. Unlike ventilation, sympathetic activity remained elevated for at least 20 min after removal of the chemical stimuli (150 +/- 10% of baseline in the last 5 min of the recovery period). Intermittent asphyxia caused a small, but statistically significant, increase in heart rate (64 +/- 4 beats/min in the final 5 min of asphyxia vs. 61 +/- 4 beats/min in baseline); however, this increase was not sustained after the return to room-air breathing. These data demonstrate that relatively short-term exposure to intermittent asphyxia causes sympathetic activation that persists after removal of the chemical stimuli. This carryover effect provides a potential mechanism whereby intermittent asphyxia during sleep could lead to chronic sympathetic activation in patients with sleep apnea syndrome.

Using interactive voice response technology and timeline follow-back methodology in studying binge eating and drinking behavior: different answers to different forms of the same question?

As part of a study of the relationship of binge eating, alcohol use, mood, and stressors, we compared the results of two forms of reporting on binge eating and drinking behavior. Forty-three first-year college women participated in an interactive voice response (IVR) study for 12 weeks. Participants answered computer-administered questions daily via IVR technology on number of eating binges and number of alcoholic drinks consumed. After 12 weeks, participants completed a Timeline Follow-back (TLFB) interview retrospectively for number of binges and drinks in the past 12 weeks. Results of this distally retrospective methodology (commonly used in drinking research and applied here also to binge eating) were compared to the results of daily IVR reporting. There was convergence across measures for drinking behavior, but divergence between IVR and TLFB for binge eating reports. TLFB reports underrepresented actual binge eating frequency, which calls into question the validity of applying this methodology to the assessment of binge eating.

Long-term efficacy of nonsurgical urinary incontinence treatment in elderly women.

BACKGROUND: Although urinary incontinence affects up to 35% of community-dwelling elderly women, the long-term efficacy of conservative treatment in this population is unknown. METHODS: Between April 1991 and January 1994, 81 community-dwelling women over age 60 underwent nonsurgical incontinence treatment that included pelvic muscle exercises, bladder retraining, estrogen replacement, biofeedback, functional electrical stimulation, and pharmacologic therapy. Information about intercurrent medical problems, urogynecologic diagnoses, treatment recommendations, and provider-documented outcome were collected from medical records. We mailed structured questionnaires evaluating persistent incontinence, treatment efficacy, interval therapy, and quality of life to women who had last attended clinic at least one year previously. RESULTS: Fifty-three of 81 (65%) women, mean age (+/- SD) 76 +/- 8 years, returned the questionnaire. The mean follow-up interval was 21 +/- 8 months. At follow-up, 43% of women reported incontinence was not a problem or mild, 33% reported moderate incontinence, and 21% reported severe incontinence. When patients compared their initial with current incontinence severity, improvement was significant (p < .01). Genuine stress incontinence was diagnosed in 18 women, detrusor overactivity in 14, and mixed incontinence in 13. Improvement did not vary consistently by incontinence diagnosis. Older patients had more severe incontinence at presentation (r = .94, p = .02) and reported less improvement (r = .97, p < .01) than younger ones. However, the overall likelihood of improvement was greatest among patients with the most severe incontinence at presentation (r = .534, p < .001). Subjects considered pelvic muscle exercises, delayed voiding, and caffeine restriction most effective in reducing incontinence severity. CONCLUSIONS: Elderly women derive long-term clinical benefit from nonsurgical incontinence therapy. Younger patients and those with more severe incontinence are most likely to respond to treatment.

Coincident plasma ACTH and corticosterone time series: comparisons between young and old rats.

Senescence is accompanied by a reduced ability to respond to a variety of physical and behavioral stressors. A sizable literature has been devoted to the interplay between hypothalamic-pituitary-adrenocortical axis dysfunction and senescence; yet, the precise interactions remain an enigma. Adrenocorticotropic hormone (ACTH) is secreted in pulsatile bursts generating complex signals in the plasma compartment that must be "read" by adrenocortical cells in order to initiate appropriate secretory responses. We have previously demonstrated subtle differences between young and old rats in the pattern of fluctuations in plasma ACTH concentrations over time, despite no difference in mean levels. The present work addressed the physiological significance of these differences in the plasma ACTH signal by analyzing the corresponding plasma corticosterone concentration time series and the relationship between these two hormones over time. Time series of integrated 10-min ACTH and corticosterone concentrations were collected over 4 h at the time of diurnal activation and analyzed in the time and frequency domains. The time of onset of the diurnal surge occurred 20 min later in old rats, and the ratio of corticosterone to ACTH was less at the time of onset and peak of the diurnal surge. Corticosterone levels were lower in old rats and mean ACTH and corticosterone levels were correlated in young but not old rats, as were maximum levels of the two hormones. Cross-correlation of ACTH and corticosterone time series and comparison of spectra were consistent with smoother fluctuations in plasma corticosterone in old animals with less variability at time scales less than 55 min. We conclude that age may be associated with a delay in diurnal activation of the HPA axis, a loss of sensitivity of adrenal corticosterone secretion to plasma ACTH levels, and a relative loss of high frequency variability in the corticosterone signal, as seen in many physiological systems with age.

Model simulations of ACTH pulsatility.

Using high intensity venous sampling (1-2 min integrated intervals) we have observed rapid (< 10 min) large amplitude (up to 80 pg/ml) fluctuations in plasma ACTH concentrations in addition to variations at longer time scales. We developed a mathematical model to assess whether plausible physiological explanations could account for our observations and compared model simulations with time series from two human subjects. Three key features enabled the model to accurately simulate the observed time series. 1) The pattern of instantaneous secretory events comprising a pulse followed a Poisson process during baseline activity and rapidly shifted to a step function pattern during a pulsatile episode. 2) The fraction of secreted ACTH shunted between a fast and slow clearance mechanism varied biphasically between baseline and pulsatile states. 3) A brief rate-sensitive suppression of secretion was invoked when secretory rates increased above a threshold amount.

High intensity venous sampling reveals subtle alterations in plasma adrenocorticotropin patterns in old rats.

Dysregulation of the hypothalamic-pituitary-adrenocortical axis has been theoretically linked to the processes of aging for decades. To investigate the effects of age on high frequency rhythms of plasma ACTH at the time of circadian activation, integrated 2-min blood samples were collected over 4 h in 10 young and 14 old rats with simultaneous plasma volume replacement. Plasma ACTH time series were analyzed in the time and frequency domains. Relative to young rats, old rats had a significantly later onset of the diurnal surge, more spectral power (R2) at lower frequencies, a lack of correlation between the slope of the spectral background continuum and the R2 at periods less than approximately 11 min, a stretching of the time scale in the composite spectra by 18.5%, and an amplitude reduction of the major composite spectral peak by 31%. These findings support the existence of subtle, but significant, alterations in the pattern of plasma ACTH with age and a delayed response of the hypothalamic-pituitary-adrenocortical axis to circadian activation. The differences in spectra suggest a weaker coupling with age between the high frequency signal input (that may reflect depolarization of groups of corticotrophs) and the system response, which could account for the delay in onset of the diurnal surge seen in the time domain.

High resolution spectral analysis of plasma adrenocorticotropin reveals a multifactorial frequency structure.

Time series of plasma ACTH concentrations were analyzed with a high resolution spectral analysis program based on digital Fourier transforms. Both coherent signal and stochastic aspects of the time series were analyzed. Samples were collected at 2- and 15-min intervals in control rats and rats immunoneutralized against CRH. The individual and composite spectral distributions revealed significant structure at both the higher and lower ranges of frequencies studied, with multiple periodicities between 4-220 min in both groups. CRH immunoneutralization consistently reduced the amplitude by 82% and compressed the frequency distribution for waveforms with periods longer than 15 min by 23%. A systematic break in the slopes of the background continua occurred between 10 and 15 min in the 2-min time series. This break was unaffected by CRH immunoneutralization. Digital Fourier transform analysis of our ACTH time series suggests a system with a more complex high frequency structure than has previously been appreciated. Our analyses suggest a biological system with the following characteristics: 1) both a fast and a slow response to a fairly constant unspecified fast forcing; 2) the slow response is initiated by the fast response and represents an imperfect integration due to feedback processes; 3) CRH alters the ability of the fast forcing to elicit a slow response without altering the fast response or ACTH clearance; and 4) this alteration consists of both amplitude and frequency modulation in the signal output. This view of ACTH secretion suggests an adaptive and energy-efficient system.

Volcanic activity and climatic changes.

Radiocarbon dates of volcanic activity suggest variations that appear to be related to climatic changes. Historical eruption records also show variations on the scale of years to centuries. These records can be combined with simple climatic models to estimate the impact of various volcanic activity levels. From this analysis it appears that climatic prediction in the range of 2 years to many decades requires broad-scale volcanic activity prediction. Statistical analysis of the volcanic record suggests that some predictability is possible.