J. Biomedical Science and Engineering, 2009, 2, 227-238
doi: 10.4236/jbise.2009.24036 Published Online August 2009 (http://www.SciRP.org/journal/jbise/
Published Online August 2009 in SciRes. http://www.scirp.org/journal/jbise
Frequency sensitivity of nanosecond pulse EMF on
regrowth and hsp70 levels in transected planaria
Ash Madkan1*, Avary Lin-Ye1, Spiro P. Pantazatos2, Matthew S. Geddis3, Martin Blank2, Reba Goodman1
1Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, USA;
2Department of Physiology and Molecular Biophysics, Columbia University College of Physicians and Surgeons, New York, USA;
3Department of Science, Borough of Manhattan Community College-CUNY, New York, USA.
Received 30 June 2009; revised 10 July 2009; accepted 15 July 2009
Purpose: To study the effect of time varying/
pulsing electromagnetic fields (PEMF) on bio-
logical systems by measuring regrowth and the
induction of elevated levels of the stress protein
hsp70 in the regenerative model Planaria Duge-
sia dorotocethala. Objective: The outcomes of
studies using electromagnetic fields (EMF) are
dependent on pulse design, field strength (mG),
frequency (Hz), duration and magnetic field/rise
time (dB/ dt). Standardization of effective pulse
design is necessary to avoid continuing confu-
sion in the investigation of pulsing electro-
magnetic field (PEMF) technology. Information
from studies on hsp70 protein induction and
regrowth in transected Planaria provides in-
formation on EMF efficacy for potential clinical
application in the treatment of ischemia reper-
fusion injury and the eventual inclusion of EMF
prophylaxis prior to surgery. Materials and
methods: Planaria were transected equidistant
between the tip of the head and the tip of the tail.
Individual head and tail portions from the same
worm were placed in pond water and exposed to
8, 16 or 72 Hertz PEMF for one hour daily post
transection under carefully controlled exposure
conditions. Regrowth of heads and tails was
measured in PEMF-exposed and sham control.
Protein lysates from PEMF-exposed and sham
control transected heads and tails were ana-
lyzed for hsp70 levels by Western blot analyses.
Conclusion: The degree of regrowth and hsp70
levels in transected heads and tails exposed to
nanosecond PEMF exposures at 8, 16 or 72 Hz
was frequency dependent. There are currently
several views on the interaction mechanism
involved in regrowth. Here we discuss two: in
one [7,8] we propose a direct effect on the DNA
of the PEMF consensus sequence, nCTCTn,
referred to as electromagnetic field response
elements (EMRE) in the promoter region of the
stress response gene HSP70. In the second
mechanism  it is proposed that EMF induce
vibrations of proteins through a series of quan-
tized low frequency phonon signals.
Keywords: Planaria; Nanosecond EM Pulse; hsp70
Electromagnetic fields (EMF) of less than 1 Gauss
strength have been shown to induce a variety of specific
effects in cells and tissues over a wide frequency range of
the EM spectrum [7,8]. Nanosecond pulsing electromag-
netic field (PEMF) technology has assumed increasingly
greater importance in clinical treatments [15,29,70]. As a
measure of efficacy, we used the regenerative model Pla-
naria, to test three nanosecond PEMF devices on regrowth
of transected heads and tails and the induction of the stress
response protein hsp70 [42,43,44,45].
Previously we showed that ELF-EMF induce elevated
hsp70 protein levels through the responsiveness of a
specific consensus DNA sequence EMRE (electromag-
netic field response element, nCTCTn) on the heat shock
70 (HSP70) promoter [41,42,43,44,45]. This DNA do-
main is upstream from the heat shock domain. Further-
more, ELF-EMF induction of the hsp70 protein protects
cells and limits the effects of subsequent stress, includ-
ing sudden changes in temperature [12,30].
The degree of electromagnetic field-effects on bio-
logical systems is known to be dependent on a number
of criteria in the waveform pattern of the exposure sys-
tem used; these include frequency, duration, wave shape,
and relative orientation of the fields [6,29,32,33,39,40].
In some cases pulsed fields have demonstrated increased
efficacy over static designs [19,21] in both medical and
Abbreviations: Extremely low frequency (ELF), electromagnetic fields
(EMF); nanosecond pulsing electromagnetic field (PEMF), heat shoc
rotein (hsp), heat shock gene (HSP), frequency (Hz), Gauss (G), mag-
netic field/rise time (dB/dt); mitogen-activated protein kinase (MAPK).
228 A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238
SciRes Copyright © 2009 JBiSE
To examine the effects of PEMF on regrowth follow-
ing transcetion and the induction of hsp70 protein in
transected heads and tails, Planaria, a Platyhelminth,
were used as a model organism because of its recognized
ability to regenerate . Previous studies showed that
EM sinusoidal fields enhance the first three to six days
of regeneration in Planaria and during this time specific
proteins in the MAPKinase cascade are activated .
Planarians regenerate through a well defined stem cell
system by restimulating mechanisms that guide the pat-
terning of body structures during embryonic develop-
ment [1,2,3,13,14,56,57,58,59]. Planaria are typically
able to regenerate into a full worm from any body part
within 14-16 days [55,32,33] thus providing a sensitive
model for examining how electromagnetic fields interact
with specific stages of regeneration.
The potential application of the upregulation of the
HSP70 gene by both ELF-EMF and nanosecond PEMF
in clinical practice would include trauma, surgery, pe-
ripheral nerve damage, orthopedic fracture, and vascular
graft support, among others. Regardless of pulse design,
EMF technology has been shown to be effective in bone
healing , wound repair  and neural regeneration
[31,36,48,49,51,63,64,65,66]. In terms of clinical applica-
tion, EMF-induction of elevated levels of hsp70 protein
also confers protection against hypoxia  and aid myo-
cardial function and survival [20,22]. Given these results,
we are particularly interested in the translational signifi-
cance of effect vs. efficacy which is not usually reported
by designers or investigators of EMF devices. More pre-
cise description of EM pulse and sine wave parameters,
including the specific EM output sector, will provide con-
sistency and “scientific basis” in reporting findings.
. MATERIALS AND METHODS
Planaria. Dugesia dorotocethala (Carolina Biological
Supply Company; cat. # 132950) were shipped overnight
and allowed to ‘recover’ for at least 24 hours in fresh
oxygenated pond water (Carolina Biological Supply Co,
NC, USA). Planaria were maintained in near darkness at
22 to 24o C (Precision Scientific incubator; Fisher Scien-
tific, NJ, USA) throughout the experiments.
2.1. Experimental Protocol
Planaria Dugesia dorotocethala were transected equidis-
tant between the tip of the head and the tip of the tail
(Figure 1). The following is the experimental protocol
used in these experiments:
1) Following transection (0 time) head and tail por-
tions were exposed to 8, 16 or 72Hz nanopulse for
one hour twice a day. Measurements of regrowth
were performed from 0 time to at least three day
intervals (n = > 10 experiments).
2) Following transection, heads and tails were ex-
posed to 8, 16 or 72 Hz up to 180 minutes. Samples
were removed at 20 minute intervals for protein ex-
traction and hsp70 analyses (n = >10).
3) Following transection, heads and tails were ex-
posed to 8, 16 or 72 Hz fields for one hour twice
per day over a 12 day time period. Ten head and tail
samples were removed daily and prepared for
hsp70 analyses. Experiments were repeated at least
Exposure protocol. In the experiments described here,
Planaria Dugesia dorotocethala were transected equidis-
tant between the tip of the tail and the head (Figure 2).
Each head and tail portion was photographed using a
Nikon digital camera mounted on a Wilde dissecting
microscope. Images were stored in a database for sub-
sequent measurements using ImageJ (see section on
Quantitation). Head and tail portions were placed in
Figure 1. Transection of Planaria. The image in the left panel shows an intact sham exposed planaria with head
facing up. The arrow indicates the transection point. The adjacent panels show representative images of heads
and tails from transected Planaria at days 0, 3, and 9. The images have been enlarged 16X to show detail.
A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238 229
SciRes Copyright © 2009 JBiSE
250ns width @ 72 Hz
Figure 2. EM Probe Device. This device is designed to generate fast magnetic field pulses of low duty cycle in the
near field region. The pulse length is about 250ns driven by a storage capacitor and a MOFSET switch that produces a
10A current in a field generating circuit element. The circuit element is just the single loop of the capacitor and switch
circuit and does not contain any additional coil or turns of a conductor to enhance the magnetic field strength. The
compact single loop design minimizes inductance and increases the speed of the circuit allowing a fast rise pulse pro-
ducing a maximum magnetic field of the order of one Gauss at about 1cm from the device. The field is concentrated in
a region of a few cm3 and falls off rapidly outside that region. The fast rise and fall of the current and magnetic field
pulse implies a broad spectrum of Fourier components contain within the repeated pulse of the waveform. For the
pulse rise time of about 10ns and a pulse frequency of 72Hz, those components extend from the fundamental fre-
quency at 72Hz at the low end to at least 20MHz at the high frequency end. The particular distribution of frequen-
cies is determined by the usual methods of Fourier analysis from the exact pulse shape. This wide range of fre-
quency offer resonant interactions with the biological mechanisms of the organism being treated over a very wide
range and could include molecular, cellular and multicellular level interactions.
separate Petri dishes (Falcon 351007 60 x 15mm; Fisher
Scientific, NJ, USA) containing pond water approxi-
mately 0.6cm deep. Dishes were numbered so that heads
and tails of the same worm could be identified for meas-
urements. Dishes were placed on a firm base and the
PEMF devices were attached to the dishes so that the
entire area of the dish was exposed to a uniform field for
one hour a day. All exposures took place within an incu-
bator with the temperature maintained at 22-24o C and
monitored with a thermocouple probe (sensitivity +/-
0.01oC; Physitemp, model BAT12, Hackensack, NJ,
USA). Growth was assessed at three-day intervals from
day 0 (immediately following transection and the onset
of PEMF exposure) to day 12 post-transection. In a se-
ries of separate experiments, pigmented eye spot devel-
opment was monitored at 12 hour intervals in transected
tails exposed to PEMF and sham control immediately
The nanosecond PEMF device (EM-PROBE
Technologies) in Figure 1 generates a near field fast
magnetic pulse of 250 nanosecond (ns) duration, which is
driven by a circuit containing a storage capacitor and a
switch that produces a 10 A current in a field-generating
circuit element. The single loop circuit does not contain
any additional coils of a conductor to enhance the mag-
netic field strength, and allows a rapid dB/dt pulse design
producing a magnetic field of 1 Gauss approximately 1 cm
from the device. The pulse begins with a peak strength of
1.4-1.7 Gauss that deteriorates to zero in about 200ns. At
72Hz this means that there is an active field for 0.00072%
of the time. At 16 Hz there is an active field for 0.00016%
of the time. At 7.8Hz there is an active field for 0.000078%
of the time. The particular distribution of frequencies is
determined by Fourier analysis from the exact pulse shape.
This wide range of frequencies offers resonant interactions
with the biological mechanisms of the organism being
treated. The entire output circuit is optimized for rapid
response by minimizing inductance. The wide range of
frequencies offers resonant interactions with the biological
mechanisms of the organism being treated over a wide
range and might include molecular, cellular and multi-
Shielding: Both active (experimental) and sham- ex-
posed (control) samples were enclosed in 30cm high,
15cm diameter cylindrical Mu metal containers (0.040"
thickness) (Amuneal Corp. Philadelphia, PA). Detailed
measurements of background magnetic fields in the in-
cubator, harmonic distortion, DC magnetic fields and
mean static magnetic fields in the incubators were pre-
viously determined .
Protein lysates. In a separate series of experiments,
protein was extracted at defined time periods from the
transected heads and tails, both experimental and sham,
to determine effect of PEMF on hsp70 levels. Lysates
were prepared from the heads and the tails of exposed
and sham exposed Planaria for analyses of hsp70 [41, 42,
230 A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238
SciRes Copyright © 2009 JBiSE
45]. Protein concentrations were determined by the
Bradford assay (Bio-Rad Redmond, WA, USA).
Western blot. Lysed samples containing 30µg of pro-
tein were subjected to sodium dodecyl sulfate gel elec-
trophoresis (Fisher Scientific, NJ, USA) on 10% poly-
acrylamide gels using appropriate molecular weight
markers (Santa Cruz Biotechnology Inc, Santa Cruz, CA,
USA) and the polypeptides were transferred to polyvi-
nylidene fluoride membrane for immunoblotting. Blots
were probed with anti-hsp70 antibody (1:10,000). The
blots were then stripped using SuperSignal West Pico Sta-
ble Peroxide Solution (Pierce, prod # 1859674, Fisher
Scientific, NJ, USA) and SuperSignal West Pico Luminol
Enhancer Solution (Pierce prod # 1859675, from Fisher
Scientific, NJ, USA) and reprobed with anti-actin (1:1000)
to confirm equivalent loading. Visualization was by the
enhanced chemiluminescent detection system (Fisher
Scientific, NJ, USA) as previously described .
Antibodies. The antibody to hsp70 was kindly provided
by Dr. Richard Morimoto, Northwestern University.
Statistical analysis: For determination of regrowth,
multiple high-resolution digital pictures of Planaria
heads and tails were taken at three day intervals and the
rate of regrowth quantified using ImageJ v1.38 (http://
rsb.info.nih.gov/ij). Length measurements were cali-
brated in millimeters and transposed to an Excel spread-
sheet for statistical analysis. Lengths were normalized to
the 0-time. Length differences over each 3-day interval
were then subjected to 2-sample t-tests to assess signifi-
cant differences in mean growth between the control and
exposed conditions for both heads and tails. An addi-
tional analysis was conducted in SAS v9.1 (www.
sas.com) to assess the significance of an interaction ef-
fect, i.e., whether the exposure had greater effect on ei-
ther heads or tails. For this a ‘mixed effects’ analysis was
performed which modeled the average length at 3-day
intervals as a linear sum of the fixed effects of exposure
(experimental vs. control), worm portion (heads vs. tails)
and their interaction.
For quantification of the hsp70 and beta-actin levels
the films from Western blot were scanned and saved as
digital images (Figure 3). The densities of the bands
were quantified using the histogram function in ImageJ
and values transposed to Excel for statistical analysis (2
sample t-tests). A minimum of three replications of each
assay were conducted.
2.2 Western Blots Quantitation of Hsp70
and β-actin Bands
Images from films were scanned into a computer and
analyzed with Image J v1.37 (NIH). The analyze func-
tion for gels was used to plot the spatial signal density
for each lane of hsp70 (see Figure 2). The same was
done for the β-actin controls (not shown). Figure 2 plots
the mean hsp70/-actin ratios for PEMF and Control con-
ditions. These values were imported into a Microsoft
Excel spreadsheet where the signal value of hsp70 was
divided by the value of the-actin signal in the same lane
in order to normalize against variable loading volumes.
-actin is a housekeeping gene and unaffected by EMF or
PEMF. Statistical analyses were also conducted in Excel
using the Data Analysis toolbox.
The extraordinary ability of Planaria to regenerate after
injury is attributed to the presence of totipotent neoblasts
capable of differentiating into all of the tissue types [1,
4]. Perhaps most impressive is their ability to regenerate
the nervous system. When transected the tail region
forms a new head complete with bilateral optic nerves
and eyes, a two-lobed brain, and a pair of ventral nerve
cords (VNC) [2,13,14].
3.1. PEMF Accelerates Rate of Regrowth of
To assess the efficacy of the nanosecond PEMFs on
Planaria regeneration, the length of ELF-EMF-exposed
and sham control heads and tails were measured at three-
day intervals starting immediately following transection
(Figure 4 A,B,C). The heads and tails of all transected
Planaria (experimental and control) regrew to normal
viable worms. The initial experiments used PEMF at
72Hz.to measure regrowth of transected heads and tails.
As previously demonstrated using ELF-EMF , ac-
celerated tail regrowth was significant at days 3 and 6
post transaction (p=0.05). In contrast to the effect of
exposure to72 Hz PEMF, 8Hz PEMF exposure on the
tail portion showed the greatest response to any of the
Figure 3. Images from films were scanned into computer and
analyzed with Image J v1.37 (NIH). The ‘analyze function for
gels’ was used to plot the spatial signal density for each lane of
hsp70. The same was done for the β-actin controls (not shown).
These values were imported into a Microsoft Excel spreadsheet
where the signal value of hsp70 was divided by the value of the
β-actin signal in the same lane in order to normalize against vari-
able loading volumes. β-actin is a so-called ‘housekeeping gene’
and unaffected by EMF or EMP. Statistical analyses were also
conducted in Excel using the Data Analysis toolbox.
A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238 231
SciRes Copyright © 2009
frequencies to which the transected heads and tails were
exposed. The sham control samples in general showed
very little change in length over this time period (Figure
3B). A reduced response to the 16Hz PEMF (Figure 3C)
was measured in both transected heads and tails when
compared with 72 and 8Hz (Figure 3A, B).
EM Probe Regeneration - 72 Hz TAILS (normalized)
Ratio to Day
EM Probe 72 Hz
Figure 4A. Regeneration of heads and tails following transection of Planaria. Histograms show-
ing the mean length of control and PEMF-exposed heads and tails immediately post-transection (0
time), and 3 to 9 days post-transection. (A) Mean length ± 2 standard error of the mean (SEM) of ex-
posed heads (HE, n=48) and sham exposed heads (HC, n=27) at each time. (B) Mean length ± 2SEM
of exposed tails (TE, n=20) and sham exposed tails (TC, n=12) at each time. The asterisks indicate a
significant statistical difference in the rate of regeneration between exposed and sham exposed heads
and tails assessed by 2-sample t-tests of mean difference in length.
A. Exposure to 72Hz accelerated tail regrowth was significant at days 3 and 6. post-transection [data
normalized against day zero (n=3)]. The effect of the 72Hz EM probe is `statistically significant
(p=0.05) at three and six days on the tail portion. The heads and tails of all transected Planaria (ex-
perimental and control) regrew to normal viable worms by 20 days. There was little or no measure-
able effect on regrowth in head portion.
EM Probe Regeneration - 8 Hz TAILS (normalized)
Ratio to Day
EM Probe 8 Hz
Figure 4B. In contrast to the effect of exposure to 72 Hz PEMF, transected tails exposed to the 8Hz EM
probe show a steady increase in length. The effect of 8Hz PEMF on the tail portion showed the greatest
response to any of the frequencies to which the transected heads and tails were exposed. The sham con-
trol samples and the head exposed samples showed very little change in length over this time period.
232 A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238
SciRes Copyright © 2009 JBiSE
EM Probe Regeneration - 16 Hz HEADS (normalized)
Ratio to Day 0
EM Probe 16 Hz
Figure 4C. A reduced response to the 16Hz PEMF was measured in both transected
heads and tails when compared with 72 and 8Hz.
Of particular interest was the general trend of the re-
sponsiveness of the tail to the three frequencies tested as
compared to the head portions (Figure 4 A, B, C). The
third day after transection has been shown to be the time
of maximal ELF-EMF-stimulated growth of the tail .
During normal regeneration this is the developmental
stage when the neural networks are actively forming [13,
14] and the ventral nerve cords (VNC) are extending
from the head into the newly formed tail.
3.2. PEMF Activation of Hsp70 Associated
with Injury and Repair
A significant elevation in hsp70 levels was evident in tail
portions that were exposed to the nanosecond PEMF
using all three frequencies at 0, 20, 40, 60 and 80 min-
utes (Figure 5). We also looked at potential differences
in induction of hsp70 protein, comparing all separate
PEMF exposures to the sham control. Tails that were
exposed to 16Hz EM-Probe fields showed the highest
hsp70 production (p= .000007.91).
In terms regrowth, the 8Hz tails shows the quickest
response to PEMF (Figure 4B). The 72Hz also shows a
noted difference between exposed and unexposed worms
(Figure 4A). The 16Hz was too inconsistent in order to
draw any conclusions (data not shown).
We believe the accelerated regrowth above is consis-
tent with the role of hsp70 as a chaperone that monitors
the folding of proteins during repair. PEMF induction of
the HSP70 gene may result from events triggered by the
activation of ERK that utilize a unique consensus se-
quence (electromagnetic field response element; EMRE)
upstream from the heat shock consensus sequence [8,
The increase paralleled the accelerated regeneration
noted above and is consistent with the role of hsp70 as a
chaperone that monitors the folding of proteins during
repair. Induction of the HSP70 gene may result from
events triggered by the activation of ERK that utilize a
unique consensus sequence (electromagnetic field re-
sponse element; EMRE) upstream from the heat shock
consensus sequence [42,47]. Stress response protein
hsp70 levels are elevated after exposure to PEMF [43,
44,45]. We next examined the effect of nanosecond
PEMF at 8, 16 and 72 Hz exposures on levels of this
protein. Earlier studied had shown that hsp70 levels
(Figure 5A,B) depicts mean hsp70/-actin ratios and 95%
CI for both 16Hz and 72Hz exposure conditions on
heads and tails respectively vs. their control counterparts.
With both frequencies we observed a spike in hsp70 lev-
els at 40 minutes which concurs with our previous data
[41,45] and as previously noted the hsp70 levels return
to normal levels by 120 minutes. [Mean hsp70/-actin
ratios for 16Hz EMP Heads (n=14), 16Hz EMP Tails
(n=14), 72Hz EMP Tails (n=17) and 72Hz EMP Heads
(n=13).] As expected, measurements of hsp70 during
regrowth showed little to no effect of exposures.
In the experiments reported here we examined nanosec-
ond PEMF, rapid dB/dt using 8, 16 and 72Hz EM probe
devices on induction of hsp70 levels and Planarian head
and tail regrowth post-transection. Our data show that
the induction of elevated hsp70 levels and regrowth fol-
lowing transection are frequency specific; tail portions
that regenerate nervous system, brain and eyes, are more
responsive to the EM probe device than head portions.
The effectiveness of time varying electromagnetic fields
on biological systems has been shown to be dependent
on pulse design; frequency, duration, magnetic field/rise
time (dB/dt) [29,30]. Measurements of EMF induced
A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238 233
SciRes Copyright © 2009 JBiSE
Planaria EM Pulse Solo - 16 Hz and Control
Exposure Time (minutes)
Mean Hsp70 / beta-actin Protein Levels (arbitary units)
Figure 5A. Histogram showing a quantitative analysis of hsp70 protein levels from regenerating heads,
tails, and sham controls. The relative protein levels are expressed in arbitrary units based on the intensity of
the hsp70 protein band from the Western blots. The PEMF exposed tails show an obvious spike between 20
and 40 minutes. Mean hsp70/β-actin ratios for 16 Hz PEMF heads (n=14), 16 Hz PEMF tails (n=14), 72
Hz PEMF tails (n=17) and 72 Hz PEMF heads (n=13). The control groups for each sample had a sample
size equal to that of its corresponding PEMF group. Error bars represent 95% confidence intervals (
Planaria TAILS Hsp70 - Days
Mean Hsp70 Levels
Figure 5B. Histogram showing a quantitative analysis of hsp70 protein levels from regenerating heads, tails,
and sham controls.[Mean hsp70/β-actin ratios for 16 Hz EMP heads (n=14), 16 Hz PEMF tails (n=14), 72
Hz PEMF tails (n=17) and 72 Hz PEMF heads (n=13)]. The control groups for each sample had a sample
size equal to that of its corresponding EMP group. Error bars represent 95% confidence intervals (
hsp70 levels and induction of post-transected re-growth
were used as markers for repair efficacy in this study.
Standardization of effective pulse design is necessary to
avoid continuing confusion in the investigation of puls-
234 A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238
SciRes Copyright © 2009 JBiSE
ing electromagnetic field (PEMF) technology. The data
from hsp70 protein induction and regrowth in Planaria, a
regeneration model, as a measure of EMF efficacy, sug-
gest excellent opportunity for clinical use in treatment of
ischemia reperfusion injury and the inclusion of EMF
prophylaxis prior to surgery. Our focus in these experi-
ments was on: (a) regrowth of head and tail portions
following transection, (b) immediacy of hsp70 induction
during regeneration of heads and tails, (c) levels of
hsp70 elevation during regeneration of heads and tails
and (d) duration of hsp70 elevation. We have shown that
the tail portion of the transected Planaria is more sensi-
tive to different frequencies both in the induction of
hsp70 levels and in regrowth. Furthermore, these
changes in tail metabolism occur at different times de-
pending upon the frequency used in the exposure.
4.1. Interaction Mechanisms
How weak electromagnetic (EM) fields interact with
DNA to stimulate protein synthesis remains unknown;
EMF interaction with cells and tissues has been exam-
ined in a variety of in vivo and in vitro systems including
enzyme reactions , Drosophila [25,27,72], yeast 
cultured cells [23,24,53] and on regeneration in Planaria
. Currently no definitive mechanism exists to explain
how EMF interact with DNA and proteins in cells and
tissues, although several theories have been proposed
including cyclotron resonance , and a modification
of this idea [6,37].
There is some evidence that EM fields can affect
DNA, both directly and indirectly . We have shown a
unique DNA sequence in a specific domain on the
HSP70 promoter that is sensitive to EM field exposures
and this observation has contributed to the understanding,
in part, of how ELF-EMF affects biological systems.
There are specific regions on the promoters of some
genes, HSP70 and c-myc for example, that contain this
consensus sequence and when this sequence is trans-
fected into promoter of reporter genes, these genes be-
come sensitive to EMF, whereas before they were not.
[41,42,43,44,45]. EM fields initiate up regulation of the
HSP70 gene, increase mRNA transcripts and hsp70 pro-
tein levels. The responsiveness is dependent on the
number of copies of the nCTCTn consensus sequence.
. Electromagnetically, responsive elements act as
‘sensors’. This is an HSF-1 dependent process as shown
by electrophoretic mobility shift assays (EMSA) of pro-
tein extracts from HL60 cells exposed to EMF. HSF1-
DNA binding activity was demonstrated by a super-
shifted band. The magnetic field-inducible heat shock
element-binding activity is HSE sequence-specific and
contains HSF1 .
Because of the demonstrated effect of EMF on elec-
tron transfer reactions, it has been proposed that dis-
placement of electrons in the H-bonds that hold DNA
together can lead to DNA chain separation, thus initiat-
ing transcription [7,8]. The resultant charging due to
electron displacement on the dynamics of DNA chain
separation suggests that electron transfer could favor
separation of base pairs e.g. nCTCTn, with the EM field
sensitive DNA sequence acting as the first order iterative
mechanism. In the case of Planaria the DNA in the toti-
potent stem cells created by the injury may be respond-
ing directly to the EM fields. It has been shown that
DNA-mediated charge transport and the oxidative dam-
age that results are extremely sensitive to variations in
the sequence and conformational-adaptive response
leading to stacking of the intervening bases [18,62].
Protein-binding to DNA, for example, through one or
more of the MAPKinase cascades, modulates long-range
charge transport negatively and positively depending
upon the specific protein DNA interactions in play
A possible mechanism for EMF initiation of protein
synthesis is by acting on the de-localized π electrons in
the base pairs that hold the DNA strands together. This is
one way in which the effect of EMF in ELF range can be
due to the resulting current. The charging of molecular
complexes has been shown to lead to their disaggrega-
tion , so local charging would be expected to cause
the DNA strands to disaggregate. A possible sequence of
steps may start with EMF displacing electrons and
charging DNA segments, followed by disaggregation of
DNA strands as a result of the charging.
The properties of the CTCT bases suggest that they
may be involved in the first step in a molecular mecha-
nism for EMF activation of protein synthesis. They
have low electron affinities, so electrons would be more
easily displaced by the EMF. Also, the CTCT are
pyrimidines, and when the H-bonds split between CTCT
and the GAGA (purines) bases on the complementary
chain, the smaller area that results would require less
energy, and make the disaggregation more favorable .
Two recent studies of molecular properties of DNA
add support to this proposed mechanism of DNA disag-
gregation. One paper compared the lifetimes of excita-
tion induced by ultraviolet (UV) light in different DNA
structures . Apparently, the induced fluorescence had
significantly longer lifetimes in DNA chains composed
of A and G bases than in chains with C and T bases. The
critical non-thermal stress protein sequences, the CTCT
pyrimidines, were found to have the shortest UV stimu-
lated fluorescence lifetimes. Their conjugate GAGA
purines were found to have lifetimes that are approxi-
mately an order of magnitude longer.
Fluorescence lifetimes are measured in the picosecond
time range, a relevant time scale for molecular rear-
rangements. Since the fluorescence lifetimes relate to the
properties of the excited molecule and not to what
caused the excitation, the measured UV excitation life-
A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238 235
SciRes Copyright © 2009 JBiSE
times in the picosecond range also applied to lifetimes of
perturbations due to EMF. Therefore, the studies suggest
that the conjugate segments on the DNA strands will
retain energy for significantly different lengths of time.
The shorter lasting perturbation is evidence of more
rapid dissipation of energy through collisions and a
greater likelihood of reaching a breaking point, while the
rest of the chain is a being held in place by the conjugate
A second paper  on the flexibility of the double
DNA helix found that stretching fluctuations were much
larger than expected and extended over two turns of the
DNA helix (over 10 base pairs). The double helix is ap-
parently much more flexible than would be expected
from the multiple H-bond links between the two strands,
and mechanical stresses are probably more easily trans-
mitted along the strand. The flexibility of the DNA dou-
ble helix would make the local unraveling of the two
strands proceed more easily once it starts.
These recently described properties of the DNA dou-
ble helix support the idea that CTCT sequences are
likely to play a greater role in DNA strand separation
leading to initiation of transcription. Similar responses
can occur with other base sequences, but they would
require greater energy and are less likely to occur at
lower frequencies. At higher frequencies, electron
movements are apt to be induced all along the DNA
Another approach to mechanism has been proposed
by Gordon . According to this model DNA function
is controlled by acoustic signals (phonons), which can be
enhanced via stochastic summation, i.e use of back-
ground. ‘noise’ if required, to complete the signal at the
necessary strength . This idea proposes that protein
iterative activities account for enzyme activation, chan-
nel completion, and other functions necessary for cell
homeostasis, and have been an integral part of electro-
magnetic responsive elements nCTCTn. Thus the sug-
gestion that paramagnetic/diamagnetic transduction
(damping) is a first order mechanism in this dynamic
centered around the Schrodinger equation [to create a
binary phonon signal series is extant in the literature .
According to this theory, beta sub-units direct protein
conformational adaptation in response to acoustic signal
series to complete an EM driven control circuit capable
of directing oxidation-reduction reactions (Ubbink et al.
. An alternate mechanism to variations on cyclotron
resonance has been suggested by [16,17]. Gordon 
and Panagopolus  suggest that EM fields may act as
classical “forcers” in a resonance system with paramag-
netic/diamagnetic oscillators that “damp” the EM field
via transduction into a normal mode or elementary pho-
non compatible with the intrinsic design and length of
the protein. This hypothesis suggests that displacement
of electrons in the H-bonds that hold DNA together
leading to DNA chain separation and initiating transcrip-
tion are reflections of a phonon resonance/iterative
4.2. Signaling Proteins
How does all this work? In the case of Planaria the DNA
in the totipotent stem cells created by the injury may be
responding directly to the EM fields. DNA-mediated
charge transport and the oxidative damage that results
are extremely sensitive to variations in the sequence and
conformational-adaptive response leading to stacking of
the intervening bases . Protein binding to DNA, for
example, through one or more of the MAPKinase cas-
cades, may modulates long-range charge transport nega-
tively and positively depending upon the specific protein
/DNA interactions in play [52,54].
Increased activation of the MAP-Kinase signaling
pathways and the specific protein binding activities that
normally occurs prior to upregulation of gene expression
are increased by EMF [26,34,38,72]. Protein transcrip-
tion factors in the p38 MAPK pathway are reported to be
involved during both ELF and RF exposures . In-
creased phosphorylation of specific transcription factors
entering the nucleus, bind to specific regions of the rec-
ognition sites on the promoter and are essential for the
initiation of transcription.
4.3. Potential Biomedical Applications
EM field exposures to induce hsp70 expression offer
non-invasive methods to provide cytoprotection before,
during and following surgical procedures or in areas of
highly predictable trauma, e.g. combat, contact sports. In
terms of potential biomedical applications of EM fields,
it is intriguing to consider the data presented here to-
gether with our previous reports on cytoprotection and
potential for gene therapy using a known specific DNA
sequence that is responsive to EM fields, e.g. NGF,
The stimulation of repair is a documented biological
effect of EM fields . However, some of the variability
in results obtained may possibly be related to different
responses to repair in different tissues, the exposure
protocols employed and specific pulse parameters .
With modern lightweight designs prophylactic applica-
tions are technologically feasible, and could result in
more rapid repair. Re-exposure at specific intervals
would maintain the increased levels and provide in-
Treatment with EM fields has been shown to protect
and enhance injury repair in ischemia reperfusion injury
 and enhanced regeneration of injured sciatic nerve,
in both examples, after EM field exposure was discon-
tinued . Post-EM field exposure (60Hz, 80mG sine
wave) of as little as 40 minutes, induces elevated hsp70
levels that were found to remain elevated for more than
236 A. Madkan et al. / J. Biomedical Science and Engineering 2 (2009) 227-238
SciRes Copyright © 2009 JBiSE
3 hours and remained capable of re-stimulation to the
same or higher levels using a higher or lower field
strength [8,23,24]. Gordon [28,29] suggests that para-
magnetic/diamagnetic dynamics in natively responsive
elements generate quantum signal series that control
conformational adaptation of proteins including DNA,
enzymes and membrane proteins. He notes that identifi-
cation of electromagnetic response elements in DNA
was an important first insight and has proposed that
DNA and especially promoter areas are highly respon-
sive to these signal series. Dennis and Goodwin 
examined PEMF technologies to define pulse bioeffi-
cacy and reported dB/dt or “rise time” as the critical de-
terminant within the PEMF technologies they examined.
They went on to note, “rectangular pulses with rapid
dB/dt were up to four times more bio-effective in stimu-
lating classes of genes associated with tissue restoration
following trauma compared to DC, sine wave or milli-
second designs”. Our findings tend to corroborate that
assessment, but also note the importance of specific fre-
quencies within the parameters of our study.
4.4. Summary and Conclusions
In the experiments reported here, the flatworm Planaria
Dugesia dorotocethala was used as a model system to
assess whether frequencies that are multiples of eight
induced regrowth and levels of stress response proteins
(hsp70) quicker and with longer duration of effect when
compared to a sinusoidal signal. There is good evidence,
as previously suggested by Dennis and Goodwin 
that the critical design determinant in pulsed electro-
magnetic field technologies in terms of bioefficacy is the
dB/dt or “rise time” in such designs and that rise time
bioefficacy could be based upon electromagnetically
responsive elements present in proteins, which would
imbue the protein with highly sophisticated abilities to
select harmonics necessary for homeostasis. The sig-
nificance of effect vs. efficacy is largely avoided among
designers and investigators of PEMF devices. The fail-
ure to address this question has resulted in highly vari-
able results and criticism that PEMF technology lacks
“scientific basis”. This paper is the first in an attempt to
discuss and evaluate specific frequencies in the ELF-
Dedicated in loving memory to Abraham J Kremer and Glen A
Gordon. We are grateful to Janet Wilson of Carolina Biologi-
cals and Eve Vagg, Department of Photography and Illustration
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