Delayed hypersensitivity to retrobulbar injections of methylprednisolone acetate

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.

Competing circadian effects of methylprednisolone and rat weight, light chains, immunocytoma size and survival

Eighty-four singly housed LOU rats, 43 males and 41 females, were studied (under conditions standardized for rhythmometry) for the effect of methylprednisolone sodium succinate (MP) upon a transplantable immunocytoma. Body temperature was monitored as a host reference rhythm while light chain excretion and tumor size were monitored to determine an effect upon the tumor. The MP, dissolved in a sweet solution, was consumed by the rats without any statistically significant shift in acrophase of the circadian temperature rhythm. Time dependent effects of MP treatment were observed with respect to 1) tumor size decrement and 2) the survival of treated animals, as compared to untreated animals.

Time-qualified reference intervals - chronodesms

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 optimization of aging

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.

Higher corticosterone values at a fixed single timepoint in serum from mice "trained" by prior handling

Results of "training" rodents for bioassay of synthetic corticosteroids are not consistent with expectations presumably based upon earlier implied claims stemming, perhaps, from over behavioral patterns displayed by handled as compared to nonhandled rodents (or the observer's wishful thinking?). At the timepoints investigated, "habituation" of mature mice and rats by exposure to handling, injection and killing procedures results in statistically significantly increased corticosterone concentrations. For younger animals the elevation in corticosterone concentration may also be applicable; although, it is not known to what extent we are dealing with an effect of "habituation" and/or age. Lowest hormone concentration occurred in the groups of mice housed undisturbed in an animal chamber separate from the room housing mice subjected to habituation. The results of this study suggest that for certain rodents kept in L from 0600 to 1800 "habituation" for 1 week, at least at the circadian stage corresponding to 0800, is not only ineffectual (in eliminating the rise in serum corticosterone associated with handling) but detrimental to the evaluation of synthetic corticosteroid potency by bioassay (to the extent that such a rise in exaggerated rather than reduced). In these acute experiments, methylprednisolone was more suppressive than dexamethasone and the water soluble ester-salts less suppressive than the 21-hydroxy bases. These results suggest the possibility of important differences in the distributive stage and/or the metabolism of these compounds--factors affecting the speed of onset of the desired as well as undesired effects.

Evolutionary changes in the electrocardiogram of severe progressive hypothermia

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.

Cost-benefit analysis of fluoridation in Houston, Texas

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 mice fed a single daily meal at different stages of lighting regimen

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.

Fecundity and longevity of F 1 females of Habrobracon from sperm x-rayed with 3000r

Our purpose was to compare with respect to fecundity and longevity two groups of F1 diploid virgins of Habrobracon the fathers of which had been X-rayed with 3000r. Sorting of wasps into two groups was based on low or high hatchability of their F2 haploid eggs. Wasps with low hatchability (below 60%) are heterozygous for induced embryonic lethals such as recessives and translocations; wasps with high hatchability (100–60%) are free of lethals or possibly heterozygous for mild detrimentals. The F1s showing high hatchability laid significantly more eggs on the average; the average difference in lifespan was almost statistically significant (7% level). A more sensitive analysis by regression indicated a highly significant linear regression of survival of all F1s on hatchability of their eggs: F1s whose eggs showed 100% hatchability lived 1.84 days longer on the average than those whose eggs showed no hatchability. Furthermore, the former laid 4.99 more eggs on the average than the latter. The data also showed a very highly significant positive correlation coefficient between eggs laid and survival of mothers (0.122***) and a very highly significant positive partial correlation coefficient (0.105***) with hatchability held constant. The latter indicates that the F1s which laid more eggs also live longer, regardless of the hatchability of their eggs and hence of the heterozygosity of the mothers for lethals and other detrimentals.