Inductively Coupled Electrical Stimulation - Part 4: Effect of PEMF on seed germination; evidence of triphasic inverse hormesis

2021 ◽  
Vol 2 (4) ◽  
pp. 1-44
Author(s):  
Robert Dennis ◽  
Anna Tommerdahl ◽  
Andromeda Dennis

Our objectives were to study the effects of PEMF on a non-animal living system with a simple and unambiguous biomarker: seed germination rate. We selected seeds representing three groups: high- intermediate- and low-germination-rate seeds (lettuce, bell pepper, and strawberry, respectively). PEMF was applied at 15 pulses per second (pps or Hz) to strawberry and lettuce seeds, and 3 or 15 pps to bell pepper seeds, using only one well-defined PEMF pulse waveform shape and intensity. The only PEMF variables between groups were therefore PEMF pulse rate and total number of pulses, which was taken to be the PEMF dose, equivalent to the duration of exposure at a known pulse rate. In the case of lettuce, we studied the effects of germination using only one PEMF dose compared to no-dose (PEMF -) controls, and no interactions with other pre-planting procedures. In the case of strawberry seeds, we studied possible interactions between PEMF, pre-freezing and pre-soaking of seeds immediately before planting. For bell peppers, extensive dose-response curves are reported. Total dose was calculated as D = R * t, where R = pulse rate (pulses per second) and t = treatment duration (seconds), the product yielding D (dose, i.e. total number of pulses in the PEMF treatment). Bell pepper seeds have an intermediate germination rate that allows the possibility for large and commercially important swings in germination rate both up and down, so we attempted to construct a full spectrum dose-response curve, beginning with PEMF dosing thought to be below threshold then extending into what was thought to potentially be the excessive and toxic range. We also attempted to identify which PEMF parameters are most relevant for dosing: total number of pulses versus “frequency” (pulse rate) and duration of exposure. Results: Lettuce seeds showed evidence of a positive effect of PEMF on germination rate (79% unstimulated, 92% stimulated), with no effect on average time to germination. Strawberry seeds showed little effect of PEMF on germination, if any, and no apparent interaction with pre-freezing or pre-soaking of seeds. Bell Pepper seeds showed a clear inverse hormesis response within the dose range studied, and suggested a tri-phasic response to PEMF exposure for doses in excess of those applied. Specifically, extremely low PEMF doses had a negative effect on bell pepper seed germination rate, whereas intermediate doses had significant positive effects on germination rate, and germination rate began trending down again for the highest PEMF doses, suggesting a third phase of inhibited germination for extreme PEMF dosages. This latter trend was not fully elucidated by the present data set, but is only suggested by data points at the most extreme upper dosages included in this study. Overall, these results were entirely unexpected and may be of importance, therefore independent replication of these results is advised. To explain the unexpected results, a detailed discussion of various multi-phasic dose-response curves is also included. All negative findings were included in this report, specifically to counteract the dominant practice of publication bias in the life sciences.

2011 ◽  
Vol 111 (6) ◽  
pp. 1703-1709 ◽  
Author(s):  
Megan M. Wenner ◽  
Thad E. Wilson ◽  
Scott L. Davis ◽  
Nina S. Stachenfeld

Although dose-response curves are commonly used to describe in vivo cutaneous α-adrenergic responses, modeling parameters and analyses methods are not consistent across studies. The goal of the present investigation was to compare three analysis methods for in vivo cutaneous vasoconstriction studies using one reference data set. Eight women (22 ± 1 yr, 24 ± 1 kg/m2) were instrumented with three cutaneous microdialysis probes for progressive norepinephrine (NE) infusions (1 × 10−8, 1 × 10−6, 1 × 10−5, 1 × 10−4, and 1 × 10−3 logM). NE was infused alone, co-infused with NG-monomethyl-l-arginine (l-NMMA, 10 mM) or Ketorolac tromethamine (KETO, 10 mM). For each probe, dose-response curves were generated using three commonly reported analyses methods: 1) nonlinear modeling without data manipulation, 2) nonlinear modeling with data normalization and constraints, and 3) percent change from baseline without modeling. Not all data conformed to sigmoidal dose-response curves using analysis 1, whereas all subjects' curves were modeled using analysis 2. When analyzing only curves that fit the sigmoidal model, NE + KETO induced a leftward shift in ED50 compared with NE alone with analyses 1 and 2 ( F test, P < 0.05) but only tended to shift the response leftward with analysis 3 (repeated-measures ANOVA, P = 0.08). Neither maximal vasoconstrictor capacity (Emax) in analysis 1 nor %change CVC change from baseline in analysis 3 were altered by blocking agents. In conclusion, although the overall detection of curve shifts and interpretation was similar between the two modeling methods of curve fitting, analysis 2 produced more sigmoidal curves.


2021 ◽  
Vol 12 ◽  
Author(s):  
Elizabeth M. Repash ◽  
Kaitlin M. Pensabene ◽  
Peter M. Palenchar ◽  
Aimee L. Eggler

Multi-drug combination therapy carries significant promise for pharmacological intervention, primarily better efficacy with less toxicity and fewer side effects. However, the field lacks methodology to assess synergistic or antagonistic interactions for drugs with non-traditional dose response curves. Specifically, our goal was to assess small-molecule modulators of antioxidant response element (ARE)-driven gene expression, which is largely regulated by the Nrf2 transcription factor. Known as Nrf2 activators, this class of compounds upregulates a battery of cytoprotective genes and shows significant promise for prevention of numerous chronic diseases. For example, sulforaphane sourced from broccoli sprouts is the subject of over 70 clinical trials. Nrf2 activators generally have non-traditional dose response curves that are hormetic, or U-shaped. We introduce a method based on the principles of Loewe Additivity to assess synergism and antagonism for two compounds in combination. This method, termed Dose-Equivalence/Zero Interaction (DE/ZI), can be used with traditional Hill-slope response curves, and it also can assess interactions for compounds with non-traditional curves, using a nearest-neighbor approach. Using a Monte-Carlo method, DE/ZI generates a measure of synergy or antagonism for each dosing pair with an associated error and p-value, resulting in a 3D response surface. For the assessed Nrf2 activators, sulforaphane and di-tert-butylhydroquinone, this approach revealed synergistic interactions at higher dosing concentrations consistently across data sets and potential antagonistic interactions at lower concentrations. DE/ZI eliminates the need to determine the best fit equation for a given data set and values experimentally-derived results over formulated fits.


1974 ◽  
Vol 32 (02/03) ◽  
pp. 356-365 ◽  
Author(s):  
F Haverkate ◽  
D. W Traas

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.


1962 ◽  
Vol 41 (1) ◽  
pp. 143-153 ◽  
Author(s):  
U. Henriques

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.


2005 ◽  
Vol 8 (4) ◽  
pp. E269-E274 ◽  
Author(s):  
Sydney L. Gaynor ◽  
Gregory D. Byrd ◽  
Michael D. Diodato ◽  
Yosuke Ishii ◽  
Anson M. Lee ◽  
...  

2001 ◽  
Author(s):  
Quinton J. Nottingham ◽  
Jeffrey B. Birch ◽  
Barry A. Bodt

2021 ◽  
Vol 3 (1) ◽  
pp. 181-188
Author(s):  
Peter Bracke ◽  
Eowyn Van de Putte ◽  
Wouter R. Ryckaert

Dose-response curves for circadian phase shift and melatonin suppression in relation to white or monochromatic nighttime illumination can be scaled to melanopic weighed illumination for normally constricted pupils, which makes them easier to interpret and compare. This is helpful for a practical applications.


2021 ◽  
Vol 21 (1) ◽  
pp. 69-110 ◽  
Author(s):  
Brian G. Vegetabile ◽  
Beth Ann Griffin ◽  
Donna L. Coffman ◽  
Matthew Cefalu ◽  
Michael W. Robbins ◽  
...  

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