A weak electrical current enhances intracellular delivery of therapeutic substances.

Cell membranes have electrical properties which can be measured and modified. Administering a weak electrical signal across a tissue is a technique which can be used to determine the quantity of water in the intracellular and extracellular compartments. Using this real-time method of bioelectrical impedance, it was found that a variety of stimuli (including an electrical current) can enhance the passage of water and other substances into the cell. We propose an inexpensive and safe technique which could be utilized to enhance delivery of a wide variety of therapeutic agents into cells for the enhanced delivery of antibiotics, chemotherapy or other therapeutic agents.

Fat-free mass estimation by the two-electrode impedance method.

In 202 healthy subjects (81 men, 121 women) aged 12-71 y, impedance (Z) was measured with a two-electrode analyzer. Fat-free mass was assessed by hydrodensitometry (FFMd). This population was randomized into two groups for cross-validation. In group 1 the relationship between ht2/Z at 1 MHz and FFMd was highly significant (r = 0.85, P less than 0.001). The equation for predicting FFMd from impedance, height2, weight, and age obtained in group 1 (r = 0.97) was applied to group 2 (r = 0.96) without reduction in r value. The accuracy of this equation was not different between men and women or between active and sedentary people. These data indicate that the two-electrode impedance method is a reliable and valid approach not only for the determination of extracellular water (as previously shown) but also for that of FFM.

[Edema in pregnancy. Calculation of the contents of maternal cells]. / Contribution à l'étude des oedèmes gravidiques. Estimation chiffrée du contenu cellulaire maternel.

In 1963 F.D. Moore and his colleagues described "the body cell mass", but up till now there has not been a practical method to isolate other components of the body. Electrical body impedance measurement makes it possible in pregnant women not only to separate the values relating to maternal tissues from those relating to fetal tissues but it is also possible to make out in the Lean Mass of the mother those parts that are due to extra-cellular fluid in the supporting tissues and particularly those that come from the cytoplasmic mass (water, proteins, electrolytes and dissolved substances). The method, which is founded on a well-known scientific basis, is simple and almost a-traumatic. It consists in measuring the electrical resistance given to the passage of a weak alternating current that is passed through two electrodes, one of which is placed on one hand and the other on the foot of the other side. This method gives a result in units of electricity (ohms) of the value of the active cellular component of the mother. As we know that the normal values are closely linked to the morphological features of the woman which are fixed, it is easy to determine them and compare the measurement obtained by impedance at the time the measurements are being taken. We therefore obtain an index N which is normally equal to 1 +/- 0.10 which gives evidence of an excess of cellular content when Nis greater than 1.10 or a decrease if N is less than 0.90.(ABSTRACT TRUNCATED AT 250 WORDS)

The physiological surveillance of hemodialysis sessions by the continuous measurement of L.F. impedance of the circulating blood (Thomasset's method).

Everybody grants as a fact that hemodialysis disturbances are produced by volemia variations. During H-D the vascular sector is the necessary transit medium to withdraw excessive interstitial water. If this withdrawing is greater than the coming back of the interstitial water into the vascular sector, the plasmatic volume will be decreasing. Thus, to measure the variations of the plasmatic volume in circulating blood it is sufficient to effect a continuous measurement of these ones in a transducer having a definite volume. So, by the mean of an impedancemeter, 5 kHz impedance is continuously measured between the two electrodes of the transducer, because it is known (Thomasset's method) that at 5 kHz current uses only the plasma in order to pass from one electrode to another.

Determination of body fluid compartments by impedance measurements: differences in the repartition of water between Duchenne muscular dystrophy and some neurological diseases.

Body fluid volumes were determined by impedance measurements in several groups of patients. Boys with Duchenne muscular dystrophy had decreased intracellular and extracellular fluid volumes. Patients with severe sequelae of poliomyelitis and with other severely disabling neurological diseases did not exhibit such profound alterations of their body fluid compartments.

Determination of body fluid compartments by electrical impedance measurements.

?The ratio of the LF and HF impedances appears to be an excellent and simple tool for investigation of liquid specimens, either of the total human body, taking into consideration global impedances, or of a particular organ, taking into consideration local impedances. We have sketched out in this communication a study of the global impedance ratio variations with age, but a large number of studies still remain to be undertaken in those cases of severe denutrition, as in all cases of metabolic illnesses. We can state that, in most cases, not only does the ratio decrease but that there is extreme difficulty in reestablishing normal values. Whatever action is undertaken, it seems that the intracellular liquid compartment remains insufficient with respect to that of the extracellular liquid compartment. It is as if the water will not enter in the cells or as if it were no longer retained within the cells. Finally, with this concept of impedance ratios of Zlf/Zhf a promising experimental method has been found which will, perhaps, enable better infestigations in a field which has often been left to one side.

Investigation of electrical impedance variations of dog brain tissue during experimental metabolic disturbances.

Experiments were carried out on dogs using bielectrode probes having as adequate impedancemeter. The probe is introduced via a cranial opening into the grey matter. This gives the following: a low frequency reading which is related to the extra cellular fluid component; a high frequency reading which is related to the total overall liquids; and a proportionality ratio of these liquids in the explored volume. The impedance variations are functions of the nature and intessity of vascular disturbance. Variation of the low frequency impedance (5 kHz) is the most significant. The experimental prodedure consists of: 1) Abrupt and permanent circulatory arrest; 2) Circulatory reduction by haemorrhage followed by recovery (if necessary by means of blood transfusion); 3) Anoxia by CO inhalation, recovery affected by means of O2 inhalation; and 4) Hypoglycemic coma induced by intravenous injection of insulin. The changes in the biochemical state of the cerebral tissue give very large variations of the low frequency impedance. It is these variations which are to constitute the object of this communication.