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Biomedical subjects

L E Scheving

Publications and source records attributed to L E Scheving.

At least 127 records · Page 7Linked to original sources
PubMed1967

Circadian phase relationships of thymidine-3H uptake, labeled nuclei, grain counts, and cell division rate in rat corneal epithelium.

Significant differences in the uptake of thymidine-(3)H, percentage of labeled cells, numbers of grains per labeled nucleus, and mitotic rate were noted in rat corneal epithelium along a 24-hr time scale. These were demonstrated by injecting subgroups of five animals every hour during a 24-hr period with thymidine-(3)H, sacrificing them 2 hr later, and analyzing the corneal epithelium by scintillation counter and radioautographic techniques. The increase in uptake during specific periods of the 24-hr time scale is attributed to an acceleration in the rate of DNA synthesis by individual cells and to an increase in the percentage of cells in the population actively synthesizing DNA.

Animals↗
PubMedDate not supplied

Circadian effect of ACTH 1-17 on mitotic index of the corneal epithelium of BALB/C mice.

The objective was to determine the effect of ACTH 1-17, an adrenocorticotropin analogue, on the mitotic index in the corneal epithelium of mice standardized in 12 hr of light alternating with 12 hr darkness. A question asked was whether the time of administration along the 24-hr time scale influenced any response found. The findings showed that ACTH 1-17 could, depending upon when it was administered, bring about a statistically significant decrease, an increase or even no such change in the mitotic index. The greatest responses found were increases, especially when ACTH 1-17 was administered during the dark span. Also the time after injection when the responses occurred varied. The greatest response recorded was at 12 hr after injection when ACTH 1-17 was given at 2 hr into the dark with a 641% and a 718% increase with a low (0.02 IU/kg) and a higher (20 IU/kg) dose, respectively. A 3-way analysis of variance supported the conclusion that the kind-of-treatment, time-of-treatment and treatment-to-kill interval (sampling time) are important factors when determining any response to ACTH 1-17 on the mitotic index.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Effect of ACTH 1-17 at different circadian stages on [3H]TdR incorporation into DNA.

The objective was to determine the effect of adrenocorticotropin (ACTH 1-17) on the incorporation of [3H]TdR into DNA (DNA synthesis) in the tongue, esophagus and stomach of CD2F1 mice standardized to 12 hours of light alternating with 12 hours of darkness. A question asked was whether the time of administration along the 24-hour time scale influenced any response found. The response was complex as ACTH 1-17 was capable of bringing about statistically significant increases in the incorporation of [3H]TdR into DNA at certain times, decreases at other times, or no response at still another time. In general the most marked effects of 20 IU/kg of ACTH 1-17 when compared to controls, was to decrease DNA synthesis of as much as 60% 4 hours after administration at the end of the dark or beginning of the light span. A 2- and 3-way analysis of variance supported the conclusion that the kind-of-treatment, time-of-treatment and the interval-to-kill (Sampling time) as well as their interactions are important factors when determining any response of ACTH 1-17 or placebo.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Effects of epidermal growth factor on deoxyribonucleic acid synthesis and stomach weight in hypophysectomized adult mice.

Epidermal growth factor (EGF) or saline was administered intraperitoneally to hypophysectomized adult male CD2F1 mice or intact controls at 0700 hr. Subgroups of mice were killed at 4, 8, or 12 hr after injection. EGF was shown to stimulate [3H]TdR incorporation into DNA into several organs as previously reported. The response to EGF was found to be enhanced in both hypophysectomized and fasted mice. Differences in [3H]TdR incorporation into DNA, corneal epithelium mitotic index, RNA in pancreas and kidney of hypophysectomized and intact mice are reported. EGF was shown to result in stomach enlargement due to increased luminal contents in both hypophysectomized and intact mice.

Animals↗
PubMedDate not supplied

Effect of epidermal growth factor (EGF) on [3H]TdR incorporation into DNA in ad lib fed and fasted CD2F1 mice.

The effect of EGF on the incorporation of [3H]TdR into DNA (DNA synthesis) was determined in the esophagus, liver, pancreas, and kidney in mice standardized to 12 hours (hr) of light alternating with 12 hr of darkness. A question asked was whether intraperitoneally administered EGF could alter the circadian patterns of DNA synthesis in these organs. The most marked effects of EGF were: an increase in DNA synthesis but only after a specific duration of time after treatment, ranging from 8 to 23 hr, which differed for each tissue, a similarity in the response of the esophagus in both ad lib fed and fasted mice, but not in the response of the liver, where the stimulatory effect of EGF observed in fed mice was dramatically reduced in fasted ones, and an advance in the phasing of the circadian rhythm in DNA synthesis of the esophagus by about 12 hr. In addition, no sex differences in fasted animals were found under the conditions of this study.

Animals↗
PubMedDate not supplied

Immunocytoma effect upon circadian variation in murine urinary excretion of beta-aminoisobutyric acid, beta-alanine, phenylalanine and tyrosine.

Under the conditions of disynchronization by the manipulation of both the alternation of light and darkness and the availability and unavailability of food, circadian rhythms characterize the excretion of several amino acids by inbred LOU rats bearing an immunocytoma. Large amplitude rhythms can be demonstrated for urinary beta-aminoisobutyric acid, beta-alanine, phenylalanine and tyrosine. Under the same conditions of disynchronization, control animals excrete the same compounds also with a marked circadian variation but at an invariably lower average rate. These excretory rhythms, along with those demonstrated earlier for polyamines and light-chains, are of interest as potential markers for the chronotherapy of cancer.

Amino Acids↗