Decreased retinal sensitivity in depressive disorder: a controlled study.

OBJECTIVE: To compare pupil responses in depressed patients with a seasonal pattern, depressed patients without a seasonal pattern and healthy controls as a function of daylight hours on the testing day. METHOD: Patients suffering from a major depressive episode were included in wintertime. The pupil light reflex was measured at inclusion and in the following summer using a binocular pupillometer. A protocol of low (1 lux) and high (400 lux) intensity red and blue lights was used to assess rod, cone and melanopsin-containing intrinsic photosensitive retinal ganglion cell input to the pupil reflex. RESULTS: The mean group pupil responses associated with a melanopsin-mediated sustained pupil response at 400 lux blue light were significantly reduced in the depressed subjects (N = 39) as compared to the healthy controls (N = 24) (P = 0.023). Across all groups, a reduction in number of daylight hours was significantly associated with a reduction in sustained pupil response (P = 0.007). All groups showed an equal effect of daylight hours on the melanopsin-mediated sustained pupil response. CONCLUSION: The melanopsin-mediated sustained pupil contraction to offset of high-intensity blue light is reduced in depressed patients. These results further emphasize the interaction of light exposure with depression.

Stress and metabolic control in diabetes mellitus: methodological issues and an illustrative analysis.

RATIONALE: The purpose of this article was twofold: a) to review studies of stress and glycemic control in diabetes, and b) to present a data analysis that illustrates the complexities of investigating stress in relation to blood glucose. The literature review emphasized human studies and the strengths and weaknesses of alternative designs. Special consideration was given to longitudinal investigations, and an analysis of data from the Diabetes Control and Complications Trial (DCCT) was presented to exemplify this approach. Nine individuals with Type 1 diabetes who participated in this project at the University of Iowa were studied over a period of 2 years. Stress was multiply measured (Life Experiences Survey, Hassles Scale, Perceived Stress Scale) as was blood glucose control (daily reflectance meter readings; monthly HbA1c). Within-subject time-series analyses and a combined longitudinal/cross-sectional model were used to analyze data. Two of the nine subjects manifested significant correlations between stress and HbA1c, and six subjects exhibited significant associations between stress and daily level or variability of glucose readings. The latter correlations varied in sign and appeared to cluster around specific individuals rather than a particular measure of stress or blood glucose. CONCLUSION: While the subjects may not represent the full spectrum of individuals with Type 1 diabetes, results were consistent with earlier longitudinal research in suggesting that the strength and direction of the relationship between stress and blood glucose control varies considerably between individuals.

Temporal and spatial variation of waterborne point-of-use 222Rn in three water distribution systems.

Three water supply systems in Iowa were studied to examine temporal variation of 222Rn at the point of entry and the point of use. For the three towns, 71, 9, and 0% of the maximum point-of-use 222Rn concentrations were significantly higher than the point-of-entry 222Rn concentrations. Homes connected to older water mains in two of the towns had higher 222Rn concentrations than those connected to newer water mains. In one town, the waterborne 222Rn concentrations in the home were related to the home's location along an old water main. The increase in 222Rn concentrations, after the water leaves the water plant, were attributed to radium deposits in the water distribution system. In addition, the water plant's radium laden iron filters contributed 7 Bq L-1 and 60 Bq L-1 of 222Rn to the finished water in What Cheer, Iowa, and Wellman, Iowa, respectively. Backwashing schedules in the water treatment systems greatly affected point-of-entry 222Rn concentrations. The results of this study have important implications for 222Rn sampling, required for regulatory compliance.

Alcohol availability and consumption: Iowa sales data revisited.

Recent changes in Iowa liquor control laws ended the 51-year-old state alcohol monopoly distribution system and turned the sales of bottled wine and spirits over to the private sector. The resulting increase in the availability of these beverages provided a unique opportunity to study the relationship between increased wine and spirits availability and changes in their consumption. Time series analyses of monthly sales (apparent consumption) trends showed that the increased availability had no lasting impact on consumption.