Biomedical subjects
Publications and source records attributed to W Nelson.
Methods are presented for qualifying clinical reference intervals, for individuals as well as peer groups, according to circadian and other rhythms, using chronobiologically-defined single samples or time series.
Chronobiologic facts, concepts and methods are relevant to gerontology and geriatrics. Circadian and other rhythms are prominent sources of predictable variation requiring a reassessment of the "normal range" at all ages. Changes in the characteristics (e.g., the amplitude) of these rhythms during aging emphasize the need for careful evaluation of time dependency in research and clinical practice. Manipulation of periodic environmental factors that synchronize circadian rhythms can affect lifespans in plants and animals, further supporting the suggestion of an interaction between rhythms and senescence.
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A patient with chronic cyclitis developed hyperemia of the episcleral and bulbar conjunctival vessels after retrobulbar injections of methylprednisolone acetate suspension. Intradermal testing revealed the responsible allergen to be methylprednisolone acetate; hypersensitivity could not be demonstrated by patch testing, despite use of increased concentrations.
A patient is reported who developed progressive hypothermia during therapy for adult respiratory distress syndrome. Electrocardiographic changes (sinus bradycardia, prolonged PR interval, prolonged QTc interval, "Osborn waves") were documented and correlated with body temperature. The significance of these changes is discussed and the relationship between the degree of hypothermia and the presence of "Osborn waves" is noted.
Observed need for an atraumatic manner of holding and occluding stomach and intestine led to the development of a Velcro sleeve applied to various modified gastrointestinal clamps and forceps. The sleeve was found to hold more securely with minimal coaptation than previously used instruments, and to hold more atraumatically with heavy coaptation.
Most previous cost-benefit analyses of fluoridation programs have been retrospective in approach and have biased their results in favor of fluoridation. This study performed a prospective cost-benefit analysis of fluoridating a segment of the water supply for Houston, Texas, and explicitly introduced and evaluated the time pattern of the costs and benefits. It was shown that neglect of the time structure of the costs and benefits would significantly bias the results. A benefit-cost ratio of 1.51 and a net present value (or "social profit") of $1,102,970 were found. The results are biased downwards and should be considered a lower bound. Thus the results indicate an investment in a fluoridation program by Houston would be a socially profitable one.
Circadian rhythms in systemic and cellular variables were studied in three groups of mice on different schedules of daily food accessibility: (1) only during the first 4 hours of the 12-hour light span; (2) only during the first 4 hours of the 12-hour dark span; and (3) at all times. The amplitudes of circadian variation in rectal temperature, serum corticosterone, and liver glycogen were increased by "meal-feeding" in either early light or early darkness. The overall averages of corticosterone and glycogen were also increased by meal-feeding at either stage of the lighting regimen. The time of peak values in temperature, corticosterone, and glycogen were determined by the time of food presentation, regardless of its relation to the lighting regimen. On the other hand, the interval between food presentation and peak values in the corneal mitotic index was greater when feeding was restricted to early darkness. These differences among the three groups of animals resulted in different relations among varibles at any given interval after feeding onset. Such effects concerning total bodily function, energy storage, hormonal regulation, and basic cellular processes indicate the pertinence of meal timing to nutritional research and practice.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.