A Critique of the Practice of Plotting Data Obtained in vivo on an ‘Hours after Treatment’ Format

Burns, E. Robert

doi:10.1159/000225646

Cited by 9 publications

(5 citation statements)

References 3 publications

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“…If circadian time significantly affected the response of the EAC the 2 lines in figure 9 should be very dissimilar when plotted on this format [7]. Since the data are very similar this illustrates that the EAC has a response to HU which is not altered by the circadian time of treatment with HU.…”

Section: -L 4 -I-------------------1-----------------------1-------mentioning

confidence: 92%

“…Once this has happened the rhythms in all variables (e.g. DNA-SA) in each animal are entrained to the light-dark cycle and therefore the colony rhythm is identical to each individual rhythm and vice versa [7], ' The mice were housed 5 to a cage with 5 cages per chronobiology chamber. A detailed description of these chambers and the animal care practices operative in this laboratory has been publish ed [5], 2 3 days prior to the start of an experiment body weights were obtained at 15.00 h. Almost all of the mice weighed between 29 and 31 g. Mice not weighing from 29 to 31 g were omitted from the experiment.…”

Section: Methodsmentioning

confidence: 99%

“…This lack of influence of biological time on the re sponse of the EAC to HU is illustrated in figure 9 by plotting the EAC data from the triple-dose (500 mg kg HU dose) experiment on an 'hours after treatment' formal [7]. If circadian time significantly affected the response of the EAC the 2 lines in figure 9 should be very dissimilar when plotted on this format [7].…”

Section: -L 4 -I-------------------1-----------------------1-------mentioning

confidence: 99%

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Induction of Differences in the Circadian Profiles of DNA Synthesis Between Normal and Neoplastic Cell Populations by Hydroxyurea without Perturbation of the Normal Circadian Rhythms

Burns¹

1983

Oncology

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This paper presents data which support a previously stated hypothesis that differences in phasing can be induced in the rhythms of DNA synthetic activity (DNA-SA) between normal and neoplastic cell populations in the same animal. The drug used was hydroxyurea (HU). Mice were standardized to a light-dark cycle with light from 06.00 to 18.00 h. Minimal disruption of the normal circadian pattern in DNA-SA in tongue, esophagus, and rectum occurred when 500 mg/kg HU was given at 17.00 h. The same dose of HU given at 05.00 h resulted in significant perturbation of the normal circadian pattern of DNA-SA in these organs. 500 mg/kg HU at 17.00 h did, however, significantly perturb DNA-SA in the Ehrlichias ascites cardinoma (EAC). To study this phenomenon further the following experiments were done in EAC bearing mice: (A) 500 mg/kg HU given at 09.00, 13.00 and 17.00 h; (B) 500 mg/kg HU given at 21.00, 01.00 and 05.00 h, and (C) 3,000 mg/ kg given at 17.00 h. In general, the response of the normal organs to HU varied depending on the circadian time of treatment with HU, whereas the response of the EAC was more uniform regardless of when the HU was given. By plotting the data obtained from the 3 normal organs and the EAC on the same graph specific points could be identified when: (a) maximal DNA-SA occurred in the EAC and at the same time minimal DNA-SA occurred in tongue, esophagus, and rectum, or (b) various levels of DNA-SA occurred in the EAC, but, at the same time maximal or peak levels of DNA-SA occurred in the normal organs.

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Section: -L 4 -I-------------------1-----------------------1-------mentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: -L 4 -I-------------------1-----------------------1-------mentioning

confidence: 99%

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Induction of Differences in the Circadian Profiles of DNA Synthesis Between Normal and Neoplastic Cell Populations by Hydroxyurea without Perturbation of the Normal Circadian Rhythms

Burns¹

1983

Oncology

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“…They were purchased at 6 weeks of age and kept on a 12:12 light/dark cycle (light from 0600 to 1800 CST) for 14 days prior to and throughout each experiment. The light/dark cycle does not cause circadian rhythms' to occur, it simply serves to synchronize each innate, endogenous circadian rhythm in each individual to a fixed environmental cue (Burns, 1982). In this situation the data obtained from a group of research animals are equivalent to single animal data and vice versa.…”

Section: Methodsmentioning

confidence: 99%

Circadian influence on the metaphase arrest technique in mouse cornea (light microscopy study) and rectum (flow cytometry study)

1984

Anat. Rec.

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Vincristine (VC) was used to arrest metaphases in the epithelium of the cornea and rectum. The cornea was studied by light microscopy (mitotic index). The rectum was analyzed by flow cytometry (%G2 + M). The results of a dose range finding study showed that 3.0 mg/kg body weight VC did not increase the number of metaphases in the cornea or the %G2 + M for the rectum over that recorded for a dose of 1.0 mg/kg VC. Therefore 1.0 mg/kg VC was selected as the dose to use. Mice were kept on a 12:12 light-dark cycle with light from 0600 to 1800. Mice were treated with 1.0 mg/kg VC at either 0200 or 1400. 0200 is a time when the native mitotic index is increasing toward a peak level, which is attained at 0800-1000 under these conditions. 1400 is a time when the mitotic index is decreasing to trough level, which is attained at 2000 to 2200. In one experiment, subgroups of mice were killed at +3 (0500 or 1700) and +6 (0800 or 2000) hours after VC. In a replicate experiment subgroups were killed at +2 (0400 or 1600), +4 (0600 or 1800), and +6 (0800 or 2000) hours after VC. The data from the cornea (mitotic indices) and the rectum (%G2 + M) were graphed against time. For both organs the slope of the metaphase accumulation line was different when VC at 0200 data were compared to VC at 1400 data. The conclusion reached was that by changing the biological time of the experiment one can significantly change the slope of the line obtained with the stathmokinetic technique.

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“…From Burns ER. 1982. A critique of the practice of plotting data obtained in vivo on an 'hours after treatment' format.…”

Section: Plotting Data On An “Hours After Treatment” Format Vs a “Timmentioning

confidence: 99%

Biological time andin vivo research: A field guide to pitfalls

Burns

2000

Anat. Rec.

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Biological rhythmicity is a fundamental characteristic of all life forms, from primitive bacteria to man. The molecular biology, genetics, and the neurobiology of the biological clock(s) are being elucidated. Daily (circadian) statistically significant fluctuations occur in all of the normal biological variables studied in the experimental animal and the human. Many researchers, however, are not aware of the negative impact biological rhythmicity can have on experimental design and/or data interpretation. This article serves not as a review, but as a “field guide” to the pitfalls that can occur when research is performed in the absence of an understanding of biological rhythmicity. The major topics discussed are: 1) data transfer from the diurnally in‐active/resting/sleeping lab animal to the diurnally active human, 2) frequency of sampling, 3) free‐running vs. synchronization, 4) alternating periods of resistance and susceptibility, 5) phase shifting of a rhythm, 6) the assumption that one mean ± S.E. from control animals can be “stretched” across an experimental time span, and 7) plotting data on an “hours after treatment” format vs. a “time of day” format. The hope is that by avoiding the pitfalls, biological time will become an ally in the endeavor to understand human biology. Anat Rec (New Anat) 261:141–152, 2000. © 2000 Wiley‐Liss, Inc.

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A Critique of the Practice of Plotting Data Obtained in vivo on an ‘Hours after Treatment’ Format

Cited by 9 publications

References 3 publications

Induction of Differences in the Circadian Profiles of DNA Synthesis Between Normal and Neoplastic Cell Populations by Hydroxyurea without Perturbation of the Normal Circadian Rhythms

Induction of Differences in the Circadian Profiles of DNA Synthesis Between Normal and Neoplastic Cell Populations by Hydroxyurea without Perturbation of the Normal Circadian Rhythms

Circadian influence on the metaphase arrest technique in mouse cornea (light microscopy study) and rectum (flow cytometry study)

Biological time andin vivo research: A field guide to pitfalls

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