A Critique of the Practice of Comparing Control Data Obtained At A Single Time Point to Experimental Data Obtained At Multiple Time Points

Er, Burns

doi:10.1111/j.1365-2184.1981.tb00525.x

Cited by 5 publications

(5 citation statements)

References 9 publications

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“…Conversely, at 27 and 51 h after treatment, the saline at 17.00 data points were at trough levels, but the saline at 05.00 data were at peak levels. Also, wherever the two data lines cross each other or, in other words, where the ascending and descending limbs of each rhythm intersect (10,22,34 and 46 h after treatment or every 12 h because of 180° phase displacement of the two rhythms), one would expect to find no statistically significant differences between the data. Figure 2b displays the DNA-SA data from the ton gues of the same two groups of mice.…”

Section: Resultsmentioning

confidence: 93%

“…In this situation, the normal circadian oscillation in the group undergoing multiple sampling will be considered to be a perturbation induced by the treatment (which in reality had no effect at all) if these data are com pared to a single control point. Depending upon where, in time, the single control point is obtained, a wide variety of erroneous conclusions may result [10],…”

Section: Discussionmentioning

confidence: 99%

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

Burns¹

1982

Oncology

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The erroneous and misleading conclusions that result when data obtained in vivo are plotted on an ‘hours after treatment’ format when compared to a ‘time of day’ or ‘time of circadian period’ format are illustrated. The mitotic index of the corneal epithelium and the amount of DNA synthetic activity in the tip of the tongue are the examples used. Animals were kept on a light-dark cycle with light from 06.00 to 18.00 CST. Treatment with an intraperitoneal injection of 0.2 ml of saline at 05.00 compared to treatment with saline at 17.00 resulted in no effect on either variable when the data were plotted on a ‘time of day’ format, i.e., the data from the group which received saline at 05.00 and the group which received saline at 17.00 were very reproducible. However, when the same data were plotted on the ‘hours after treatment’ format, the data were 180° out of phase with each other. This resulted in many statistically significant differences between the two groups. These differences are artifactual when compared to the ‘no effect’ or ‘no perturbation’ situation seen when the data are plotted on the ‘time of day’ format.

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Section: Resultsmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

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

Burns¹

1982

Oncology

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“…To avoid the possible diurnal or lunar variations in normal baseline values noted for other tissues [16], uninjected control groups were killed on different days of the month and different times of the day and the values were averaged.…”

Section: Materials and Methods Animalsmentioning

confidence: 99%

In vivo study of lactoferrin and murine rebound myelopoiesis

Poppas¹,

Faith²,

Bierman³

1986

American J Hematol

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Lactoferrin has been reported to inhibit the production of colony-stimulating factor (CSF); thus we sought to study its possible effects on myelopoiesis in vivo. The characteristics of rebound myelopoiesis in C57BL mice injected with a sublethal dose of cyclophosphamide (CY) were used to test lactoferrin for any granulopoietic activity. An experimental group received daily injections of 50 micrograms of human lactoferrin beginning 24 hr after CY injections. By measuring the total nucleated cellularity of the femoral marrow, the peripheral blood count, and the incorporation of tritiated thymidine by the marrow in six replicate experiments, no statistically significant difference was noted between the lactoferrin injected groups and the control groups. Neither the route of lactoferrin administration (i.v. or i.p.) nor the sex of the animal altered the myelopoietic recovery. Lactoferrin had no stimulatory or inhibitory effect on murine rebound myelopoiesis in vivo contrary to the reported in vitro results.

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“…From Burns ER. 1981 A critique of the practice of comparing control data obtained at a single time point to experimental data obtained at multiple time points. Cell Tissue Kinetics 14:219–224 (with permission from Blackwell Science Ltd.) .…”

Section: Synchronization Vs Free‐runningmentioning

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 Comparing Control Data Obtained At A Single Time Point to Experimental Data Obtained At Multiple Time Points

Cited by 5 publications

References 9 publications

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

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

In vivo study of lactoferrin and murine rebound myelopoiesis

Biological time andin vivo research: A field guide to pitfalls

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