Robert O. Becker

Generation of Electric Potentials by Bone in Response to Mechanical Stress

The amplitude of electrical potentials generated in stressed bone is dependent upon the rate and magnitude of bony deformation, while polarity is determined by the direction of bending. Areas under compression develop negative potentials with respect to other areas. Similar results were obtained both in living and dead bone. Removal of the inorganic fraction from bone abolishes its ability to generate stress potentials. It is probable that these potentials influence the activity of osseous cells directly. Furthermore, it is conceivable that they may direct, in some manner, the aggregation pattern of the macromolecules of the extracellular matrix.

The Bioelectric Factors in Amphibian-limb Regeneration

The replacement of lost body parts by a specific growth process known as regeneration is an ability shared, to a varying extent, by all living things. In general, as one follows the evolutionary sequence, the ability becomes increasingly restricted. In man, the process is limited to the regeneration of certain tissues only, notably skin and bone. In a child the diaphysis of a long bone can be regenerated provided the periosteal tube is intact, whereas in an adult a fracture of a long bone can heal by replacement of the missing portion with functional osseous tissue. Although there is little doubt that factors such as nutrition, vascularity, and immobilization all play important roles in supporting this osseous healing process, the basic processes of cellular de-differentiation and subsequent re-differentiation which produce a replica of the missing portion represent true tissue regeneration. This process of bone healing is in marked contrast to the healing mechanisms in most other human tissues in which fibrous connective tissue is used to bridge the gap. It is evident, therefore, that the process of regenerative healing must entail specific factors not operating in other less adequate types of tissue healing. To control this type of tissue healing adequately, these specific factors must be identified and themselves controlled. It is reasonable to expect that the same general controlling mechanisms are operative for all types of regeneration, and that knowledge of the regenerative process in another vertebrate may furnish a basis for a study of human regeneration. Fortunately, the peak of regenerative ability, as judged by the complexity of the structures regenerated, is present within the vertebrate phylum. The urodela, or salamanders, are present-day examples of the basic vertebrate type from which the higher vertebrates have been derived. Their fore and hind limbs are equivalent in anatomical structure and complexity to the human upper and lower extremities. Nevertheless, the larval-stage salamander is capable of regenerating a perfect replica of one of its limbs in a period of thirty to forty days. The adult salamander is similarly capable, although the required time is somewhat longer and the regenerated extremity may be slightly smaller than normal (Fig. 1). This process is so dramatically evident that it has stimulated study for literally centuries t. However, the basic controffing factors in the regenerative process and the factors operating to reduce the process in mammals have successfully resisted investigation until recently. Within the past few years, some significant observations have been made and the problem now can be approached from a new aspect. In one line of inquiry Singer demonstrated the dependence of the regenerative process upon the presence of a critical amount of nerve tissue within the amputation stump 23, He showed that this effect is not dependent on the type of nerve * Read at the Combined Meeting of the Orthopaedic Research Society and The American Academy of Orthopaedic Surgeons, Miami Beach, Florida, January 8, 1961. t Spallanzini (Prodromo, 1768): “But if the above mentioned animals recover their legshow comes it to pass, that other land animals are not endowed with the same power? Is it to be hoped that they may acquire them by some useful disposition?”

Electrical Correlates of Acupuncture Points

Employing a Wheatstone bridge, skin conductance was measured over those putative acupuncture points on the large intestine and pericardium meridians lying between the metacarpophalangeal joints and the elbow. Results were compared to those from anatomically similar locations devoid of acupuncture points. At most acupuncture points on most subjects, there were greater electrical conductance maxima than at control sites.

Effect of Magnetic Fields on Reaction Time Performance

IN previous investigations1,2 we indicated some significant empirical relationships between selected geophysical parameters and gross measures of human behaviour. The present investigation attempts to demonstrate the effects of artificially produced magnetic fields on a standard, relatively uncomplicated, psychomotor task, simple reaction time.

D.C. skin conductance variation at acupuncture loci.

Skin conductance was measured in 10 subjects with a DC Wheatstone bridge in 10 areas purportedly containing acupuncture loci on the Triple Burner (TB) and Lung (Lu) meridians. When the results were compared to those from anatomically similar locations devoid of acupuncture loci, local conductance variation was found to be significantly different (p less than 0.05) in most acupuncture locus locations.

Clinical experiences with low intensity direct current stimulation of bone growth.

Low intensity direct current stimulation of bone growth involves the continuous application of cathodic currents in the nanoampere range. The technique has been applied to 13 patients with a variety of non-unions and pseudarthroses with a success rate of 77 per cent. Preliminary data indicate that a range of total energy, from 0.6 to 2.5 Joules, is maximally effective. The technique has been combined with anodic control of local bacterial infection with promising results. Both the osteogenic stimulation and the bacterial suppression techniques as described in this paper, appear to be safe and effective.

The effect of continuous exposure to low frequency electric fields on three generations of mice: A pilot study

Mice were allowed to mate, gestate, deliver and rear their offspring for 3 successive generations while being continuously exposed to 60 Hz electric fields. Mice exposed to vertical electric fields exhibited decreased body weights at 35 days postpartum and increased mortality, rates for 3 successive generations. Mice exposed to horizontal electric fields exhibited decreased body weights for 2 successive generations.

Search for Evidence of Axial Current Flow in Peripheral Nerves of Salamander

The demonstrated association of the d-c bioelectric field with central nervous system elements implies the longitudinal flow of charge carriers within that system. Transverse d-c voltages, attributed to the Hall effect, have been obtained from the extremities of intact salamanders under circumstances suggesting such electric current. These voltages disappeared after nerve section, and their magnitude was related to the depth of anesthesia.

The significance of bioelectric potentials

Abstract A complete, operational system is proposed to exist in living organisms which controls such basic functions as growth, healing and biological cycles. The system is described in anatomical detail. It functions as a data transmission system in an analog fashion using varying levels of d.c. as its signal. The system interlocks physically with the nervous system and is postulated to be its percursor. There are two electrochemical links of great significance in the operation of the system. One is between the d.c. system and the nervous system; the other is between the d.c. system and all body cells. The concept explains all of the diverse effects reported for the biological effects of applied electrical currents including: electrical anesthesia, electrical growth control and electro-acupuncture. It also furnishes a testable hypothesis for predicting other effects that might be of clinical significance.

Piezoelectricity in hydrated frozen bone and tendon

THE piezoelectric property of connective tissue may play a role in regulating the patterns of tissue growth1. Most piezoelectric measurements, however, deal with dried tissue2–4. Observations of stress-generated voltages from hydrated connective tissue are generally insufficient to establish that the voltages are of piezoelectric origin, because of complications resulting from streaming potentials and electrode effects5–7. A report of the non-existence of piezoelectricity in hydrated collagen at room temperature8 has been criticised9. Use of the converse effect is most desirable in studying biological piezoelectricity9, but for hydrated tissue the high electrical conductivity of water interferes with the establishment of an electric field inside the sample2,4. We therefore hydrated and then froze our connective tissue samples taking advantage of the reduced conductivity of ice compared with that of water. Our results establish the existence of the piezoelectric effect in bone and tendon under physiological conditions of moisture, but at a non-physiological temperature (−25° C).