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PubMed1999

Effect of long-term use of moisturizer on skin hydration, barrier function and susceptibility to irritants.

Moisturizers are often used in the prevention and treatment of irritant contact dermatitis. The present study was to determine whether long-term daily use of a moisturizer on normal skin would affect skin barrier function, hydration state, or susceptibility to sodium lauryl sulphate. Healthy volunteers used a moisturizer on one forearm 3 times daily for 4 weeks. The other forearm served as a control. Afterwards both forearms were challenged with a patch-test of sodium lauryl sulphate. Skin barrier function was evaluated by measuring trans-epidermal water loss and skin hydration by measuring electrical capacitance. Electrical capacitance was significantly increased on the treated arm during the treatment period. After challenge with sodium lauryl sulphate, transepidermal water loss was significantly higher on the arm treated with moisturizer than on the control arm. The results suggest that long-term treatment with moisturizers on normal skin may increase skin susceptibility to irritants.

Adult↗
PubMed1998

A new system for the measurement of electrogenicity produced by ion pumps using a thin polymer film: examination of wild type bacteriorhodopsin and the D96N mutant over a wide pH range.

We developed a new assay system for the measurement of capacitive electric currents generated by ion pumps using the thin polymer film 'Lumirror' (Toray Co., Japan). This system enables us to examine the electrogenicity of ion pumps over a wide range of experimental conditions with high reproducibility due to the mechanical and chemical stability, the high electric resistance and the high electric capacitance of the thin polymer film. Using this method, we examined the photoelectric response of wild type bacteriorhodopsin and its D96N mutant over a wide pH range (2.8-10.0). The results were explained in terms of the affinities of the proton binding sites for translocated protons. A possibility that the direction of the proton transfer from the Schiff base was influenced by the protonation/deprotonation state of the surrounding proton binding sites was suggested. We also found that this film can be used as a substrate for atomic force microscopy (AFM) samples and hence the active purple membrane was observed with AFM.

Bacteriorhodopsins↗
PubMed2005

Monte Carlo simulation of the electrical differential capacitance of a double electrical layer formed at the heterogeneous metal oxide/electrolyte interface.

A semiempirical simulation study of differential capacitance c(d) is presented for the case in which the formula for the macroscopic surface potential is known. Both the differential capacity and the surface potential are treated as unique functions of the potential determining ions (H+ ions). The effects of surface heterogeneity on the surface charge density curves sigma0 = f(pH), and capacity curves c(d) = f(pH), as well as on the position of maximum capacitance are discussed. The "model" effects (influence of the model parameter on the results) are presented.

Journal Article↗
PubMed1984

Capacitative pulsed electric stimulation of bone cells. Induction of cyclic-AMP changes and DNA synthesis.

Pulsed electric stimulation, coupled capacitively to bone cells isolated from rat embryo calvaria, caused changes in the intracellular level of cyclic AMP and enhanced DNA synthesis. The capacitive method of electrical stimulation was characterized in terms of displacement currents (0.7-4.0 A) and voltages (10-54 V/cm) prevailing in the stimulation chamber. Changes, both in cyclic AMP and in incorporation of [3H]thymidine into DNA, were correlated with the strength of the applied electric field. Unlike the mechanical stimulation of bone cells, the electrical stimulus was not mediated by de novo synthesis of prostaglandins. The findings suggest that cyclic-AMP changes, induced by the capacitive electrical stimulation of bone cells, trigger DNA synthesis.

Animals↗
PubMed1985

Fracture healing in the rabbit fibula when subjected to various capacitively coupled electrical fields.

The effect of capacitively coupled electrical stimulation on the healing of midshaft transverse osteotomies of the rabbit fibula is assessed roentgenographically, mechanically, and histologically. The results show that a dose-response curve for capacitive coupling and fracture healing exists and that a 220 mV, 250 microA, 60 kHz applied electrical signal (0.33 V/cm internal electric field) is the most effective signal for fracture stimulation in this model.

Animals↗
PubMed2003

Solcoseryl, a tissue respiration stimulating agent, significantly enhances the effect of capacitively coupled electric field on the promotion of bone formation around dental implants.

In the present study we examined the combined effect of application of a capacitively coupled electric field (CCEF) and the tissue respiration stimulating agent, Solcoseryl, on the promotion of bone formation around dental implants histologically and mechanically. After a dental implant was inserted into each femur of Japanese white rabbits, Solcoseryl (2 ml/kg) was administered intravenously in the ear vein and a CCEF was applied for 4 h per day for 14 days. The degree of bone formation on microscopic observation, bone contact ratio, bone surface area ratio, and the level of removal torque of the implant in the Solcoseryl- and CCEF-treated group were significantly higher than the respective value in the control group, which had not been treated with Solcoseryl nor CCEF. Thus, the combination of CCEF stimulation and Solcoseryl effectively promoted the formation of new bone. It is suggested that the clinical use of a combination of CCEF stimulation and Solcoseryl for dental implants promotes osseointegration.

Actihaemyl↗
PubMed1983

In vivo growth plate stimulation in various capacitively coupled electrical fields.

The right proximal tibial growth plates of adolescent New Zealand white rabbits were stimulated with various capacitively coupled electrical fields. Capacitor plates attached to plastic jigs placed over the proximal tibiae were connected to function generators which supplied sine wave signals of 60 kHz frequency and various voltages (2.5, 5, 10, and 20 V peak-to-peak). At 0 h and at 48 h, each animal was labeled with intravenously injected oxytetracycline. For the next 48 h, each right proximal tibial growth plate was stimulated with one of the above electrical signals. At the end of the 48 h of stimulation, the animals were sacrificed, and the tibiae were excised; histological sections of the proximal growth plate in each tibia were made, and the distance the labels moved away from the bone-cartilage junction down into the metaphysis was measured under fluorescent microscopy. Results indicate that the rabbit growth plate can be consistently stimulated to statistically significant accelerated growth in a capacitively coupled electrical field. A dose-response effect was noted, with 5 V peak-to-peak exhibiting maximum growth acceleration. Thus, the application of the proper capacitively coupled electrical field significantly stimulated the rabbit growth plate at voltage and current levels that are safe for human use.

Animals↗
PubMedDate not supplied

Enhancing osseointegration by capacitively coupled electric field: a pilot study on early occlusal loading in the dog mandible.

Expeditious postoperative appositional growth of bone to dental implants is desired for clinically successful fixation of oral implants. The present study was performed to evaluate the effect of applying a capacitively coupled electric field (CCEF) followed by functional loading on peri-implant osteogenesis in the dog mandible. Nine adult beagles were used in this study. All premolars on both sides of the mandible were removed from each dog. A physio-odontlam implant (POI, Ti-6AI-4v) with 2 stages (3.7 mm in diameter and 8.0 mm in length), whose surface had been treated with anodic oxidation and sandblasted, was placed into each test site by self-tapping. Daily application of CCEF (8 hours per day) was initiated on the day following surgery and continued for 14 days or 21 days. After CCEF treatment was finished for each period, a prosthetic abutment and a straight post were placed on each implant. Four days after placement of the post, implants were placed under functional loading for 30 days. The dogs were then sacrificed, and histologic and radiographic studies of the mandible were performed. Relatively well calcified, mature bone with a lamellar-like structure was observed by contact microradiography and histologic study (double staining with basic fuchsin-methylene blue) of the peri-implant region on the CCEF-treated samples. In contrast, poorly calcified, immature bone without a lamellar structure was observed in control sites not treated with CCEF. The bone area ratios of the CCEF-treated sides were larger than those of control sides. These results suggest that the application of CCEF after implant placement may enhance peri-implant osteogenesis, even with functional loading.

Animals↗
PubMed1996

Effect of capacitive coupled electrical stimulation on regenerate bone.

An in vivo study was carried out to determine if capacitive coupled electrical stimulation increased the rate of recovery of strength of regenerate bone produced as a result of lengthening by the Ilizarov technique. Thirty-four adult male beagles underwent a right tibial mid-diaphyseal corticotomy, followed by a 5-day delay, and then 21 days of lengthening (1 mm/day). At the start of the post-distraction period (day 27), stimulation (3-6.3 V peak to peak, 5-10 mA root-mean-square at 60 kHz) was applied for 28 days to one group. The nonstimulated group (n = 17) underwent a 28-day period with no stimulation. From each group, four tibiae were prepared for histology; both ends of the remaining bones were embedded in polymethylmethacrylate and tested in torsion (internal rotation at 4.7 degrees/sec) until failure. Statistically significant changes included a 37% lower maximum torque capacity and a 40% decrease in strain energy to failure in the stimulated group compared with the nonstimulated group. The findings are supported by measured trends to a lower modulus of rigidity (37% decrease) and a smaller percentage of active osteoid perimeter (20% decrease) for the stimulated group. The experimental data suggest that when this dose of capacitive coupled electrical stimulation is applied to the regenerating bone created during distraction osteogenesis, it delays the recovery of bone strength compared with an untreated control.

Animals↗
PubMed1985

Prevention and treatment of sciatic denervation disuse osteoporosis in the rat tibia with capacitively coupled electrical stimulation.

Osteoporosis in the sciatic-denervated rat tibia was both prevented and reversed with a capacitively coupled electrical field. In both the prevention of the development of osteoporosis and the reversal of a previously established osteoporosis, a statistically significant enhancement of wet weight, dry weight, ashed weight, ultimate strength, cortical area, cortical thickness, and a concomitant decrease in cortical porosity occurred in the stimulated, denervated tibiae of the experimental animals compared with the nonstimulated, denervated tibiae of the control animals. These effects exhibited dose-response characteristics. A 60 kHz symmetrical sinewave signal was effective in preventing osteoporosis at a range of 5-10 peak-to-peak, and it was effective in reversing osteoporosis at 10 V peak-to-peak. Reversal of a well-established osteoporosis in laboratory animals has not been reported previously. Continued investigation into the use of a capacitively coupled electrical field in the prevention and treatment of osteoporosis seems warranted from these studies.

Animals↗
PubMedDate not supplied

Incubation of cultured skin substitutes in reduced humidity promotes cornification in vitro and stable engraftment in athymic mice.

Cultured skin substitutes have been used successfully for adjunctive treatment of excised burns and chronic skin wounds. However, limitations inherent to all models of cultured skin include deficient barrier function in vitro, and delayed keratinization after grafting in comparison to native skin autografts. Experimental conditions for incubation of skin substitutes were tested to stimulate barrier development before grafting, and measure responses in function and stability after grafting. Cultured skin substitutes consisted of human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan biopolymer substrates. Parallel cultured skin substitutes were incubated at the air-liquid interface in ambient (48-61%) or saturated (79-91%) relative humidity, and grafted to athymic mice on culture day 14. Additional cultured skin substitutes were incubated in the experimental conditions for a total of 28 days. Cadaveric human skin and acellular biopolymer substrates served as controls. Epidermal barrier was evaluated as the change in surface hydration by surface electrical capacitance with the NOVA Dermal Phase Meter. Cultured skin substitutes and cadaveric skin incubated in ambient humidity had lower baseline surface electrical capacitance and less change in surface electrical capacitance than parallel samples incubated in saturated humidity at all time points in vitro. Data from healing cultured skin substitutes at 2, 4, 8 and 12 weeks after grafting showed an earlier return to hydration levels comparable to native human skin, and more stable engraftment for skin substitutes from ambient humidity. The data indicate that cultured skin substitutes in ambient humidity have lower surface electrical capacitance and greater stability in vitro, and that they reform epidermal barrier more rapidly after grafting than cultured skin substitutes in saturated humidity. These results suggest that restoration of functional epidermis by cultured skin substitutes is stimulated by incubation in reduced humidity in vitro.

Animals↗
PubMed1985

Treatment of sciatic denervation disuse osteoporosis in the rat tibia with capacitively coupled electrical stimulation. Dose response and duty cycle.

We determined the dose-response characteristics of a low-voltage, high-frequency, capacitively coupled electrical signal that reverses an established osteoporosis in a rat tibial model with sciatic neurectomy. The electrical signals were delivered by means of stainless-steel gel-coated electrodes. In the first part of the study, the shape (sine wave) and frequency (sixty kilohertz) of the signal were kept constant while the voltage was varied from 0.01 to ten volts, peak to peak. Control osteoporotic and sham osteoporotic animals showed a mean loss of tibial ash weight of 19 and 17 per cent, respectively, twenty-eight days after sciatic neurectomy plus twelve days of no treatment using sham electrodes. Rats that were subjected to 0.25, 0.50, 1.0, 2.5, and 5.0 volts, peak to peak, for twelve days beginning on the twenty-eighth day after sciatic neurectomy all showed mean losses of tibial ash weight that were significantly less than those of the controls. The rats that had a 0.5-volt peak-to-peak signal showed the least mean loss of tibial ash weight (only 6 per cent). We concluded that a capacitively coupled electrical signal, delivered through gel-coated electrodes, can largely reverse an established disuse osteoporosis due to neurectomy in the rat tibia. In the second part of the study, the duty cycles of a sine-wave, sixty-kilohertz, 0.5-volt peak-to-peak signal were varied (12.5, 50, and 100 per cent on), and the wet, dry, and ash weights were determined and compared with those of unstimulated osteoporotic controls. Only the 100 per cent duty-cycle signal was effective in reversing the loss of bone mass in the neurectomized tibiae.

Animals↗
PubMed1988

Treatment of denervation/disuse osteoporosis in the rat with a capacitively coupled electrical signal: effects on bone formation and bone resorption.

Utilizing a sciatic neurectomy model of disuse osteoporosis, the effects on rates of bone formation and bone resorption were examined when a capacitively coupled electrical signal was applied to the denervated tibia in the rat. It was found that a low-voltage, symmetrical sine wave, 60-kHz, capacitively coupled signal had no significant effect on the amount of bone resorption occurring in denervated right tibiae in rats previously labeled with [3H]tetracycline. This was true whether the signal was applied while osteoporosis was developing (prevention of osteoporosis) or after it had been established (treatment of osteoporosis). If a similar capacitively coupled signal was applied to rats in which osteoporosis was well established, and the rats were labeled with [3H]tetracycline daily during a 12-day treatment period, it was found that there was statistically significant enhancement of the amount of new bone formation (increased [3H]tetracycline incorporation) in the tibiae that received the signal as compared with that of the controls. These results indicate that prevention or amelioration of disuse osteoporosis that occurs with a capacitively coupled electrical signal is due not to a change in the rate of bone resorption, but to an increase in the rate of bone formation.

Animals↗
PubMed1992

In vitro bone-cell response to a capacitively coupled electrical field. The role of field strength, pulse pattern, and duty cycle.

Newborn rat calvarial bone cells were grown to confluence and subjected to a matrix of sine wave 60-kHz capacitively coupled electrical signals of various field strengths, pulse-burst patterns, and duty cycles. Both [3H] thymidine incorporation into DNA and alkaline phosphatase activity were evaluated in field strengths ranging from 0.0001 to 20 mV/cm, with pulse-burst patterns ranging from continuous to 5 milliseconds ON/495 milliseconds OFF, with daily duty cycles ranging from 0.25% to 25%. A significant increase in proliferation occurred in field strengths of 0.1, 1, and 20 mV/cm when the signal was applied continuously for six hours. Significant proliferation also occurred when the 20-mV/cm field was pulsed for six hours at 5 milliseconds ON/495 milliseconds OFF and at 5 milliseconds ON/245 milliseconds OFF. No change in alkaline phosphatase activity occurred in the 20-mV/cm field with any signal. At 1 mV/cm, there was a significant decrease in alkaline phosphatase activity in the continuous signal and in the 5 milliseconds ON/62 milliseconds OFF signal; in the lower fields evaluated, there was an actual decrease in alkaline phosphatase activity with some of the signals. The field strength plays a dominant role in determining the bone-cell's proliferative response, and to a lesser extent the alkaline phosphatase activity response, to a capacitively coupled electric field. The pulse configuration and the duty cycle are also important, but only if the proper field strength is being applied to the cell.

Alkaline Phosphatase↗
PubMed1989

Treatment of castration-induced osteoporosis by a capacitively coupled electrical signal in rat vertebrae.

Castrated male Sprague Dawley rats were subjected to various capacitively coupled electrical fields for six and eight weeks at two and 4.5 months after castration, respectively, with pairs of electrodes that were located paraspinally on the surface of the skin dorsally at the eleventh thoracic and fourth lumbar levels. When the animals were killed, dry and ash weights per unit of volume (apparent density), elastic modulus, ultimate stress, work to failure, trabecular area fraction, and mean trabecular width were determined for selected vertebrae. The results indicated that a sixty-kilohertz, 100-microampere signal (a calculated current density of five microamperes root-mean-square per square centimeter and a field of twelve millivolts root-mean-square per centimeter) significantly reversed the castration-induced osteoporosis in the lumbar vertebrae and restored bone mass per unit of volume in rats that had been stimulated for eight weeks after castration.

Animals↗
PubMed1994

Effect of capacitively coupled electric fields on an experimental model of delayed union of fracture.

To evaluate the effect of capacitively coupled electric fields (CCEF) on delayed union of fractures, an experimental model of delayed union was produced in the radius of rabbits, and the process of healing was investigated by radiography, bone mineral density (BMD) measured with dual energy x-ray absorptiometry, and histological survey. It was confirmed radiographically and histologically that callus formation was enhanced in the group treated with CCEF. After stimulation, the average BMD increased more than 18% compared with the controls. Our experiment on a delayed union model suggests that CCEF is effective for the treatment of delayed union of fractures.

Animals↗
PubMed2005

Electrical measurement of moisturizing effect on skin hydration and barrier function in psoriasis patients.

Transepidermal water loss (TEWL) in psoriatic skin lesions seems to be related to the severity of the psoriasis, and the electrical capacitance and conductance of the skin are indicators of the hydration level of the stratum corneum. We compared the characteristics of these electrical measurements, in assessing the persistent effect of a moisturizing cream on skin hydration and barrier function in psoriasis patients. Seventeen Korean psoriasis patients were recruited. Their right leg was treated with the moisturizer twice daily for 6 weeks, while their left leg was used as the control site. For each patient, one psoriatic plaque on each leg was selected as the involved psoriatic lesion. Uninvolved psoriatic skin was regarded as the apparently healthy looking skin 4-5 cm away from the periphery of the psoriatic lesion. The TEWL, electrical capacitance and conductance were measured, in order to evaluate the barrier function and hydration level of the stratum corneum. The clinical and biophysical data for each patient were recorded at the start of the study and after 2, 4 and 6 weeks. The degree of skin dryness at the applied area improved progressively. The electrical capacitance at the treated psoriatic lesion increased significantly after 2 weeks, and this improvement was maintained during the entire study period. However, no noticeable change was observed in the electrical conductance. The TEWL showed an inverse pattern to that of the skin capacitance, decreasing during the study period. The skin capacitance and TEWL exhibited good correlation with the visual assessment of skin dryness, but the skin conductance did not. Our data suggest that electrical capacitance and TEWL may be useful in the evaluation of the effect of a moisturizer on the hydration status and barrier function of psoriatic skin.

Adult↗
PubMed1990

A double-blind study on the effects of a capacitively coupled electrical field on bone ingrowth into porous-surfaced canine total hip prostheses.

The effect of a capacitively coupled electrical field on bone ingrowth into titanium fiber mesh porous-surfaced canine total hip arthroplasties (THAs) was investigated in a double-blind experiment. The electrical field was induced by an external source delivering a 60-kHz 5-6-V peak-to-peak sinusoid voltage through skin electrodes. No significant increase in the ingrowth of bone into the porous coating occurred at the end of six weeks of electrical stimulation. The amount of bone that grew into the porous surface, the areal density of bone within the available pore space, and the extent of the prosthesis surface area with bone ingrowth or apposition were not significantly different in the control and stimulated groups. This particular form of electrical stimulation does not improve bone ingrowth into porous-surfaced canine THAs by six weeks.

Animals↗