Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “high voltage”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed2004

Residential proximity to high-voltage power lines and risk of childhood hematological malignancies.

BACKGROUND: Epidemiologic studies of electromagnetic fields and childhood cancers have focused on home exposure. The authors investigated whether residence in districts near high-voltage power lines is associated with childhood hematological malignancies, using small area analysis. METHODS: Among 50,000 children in a city in Japan, 14 cases aged younger than 15 years were diagnosed with these malignancies in the period from 1992 through 2001. A total of 294 districts constituting this city were classified according to their proximity to high-voltage power lines (either 66 kV or 220 kV). Mantel-Haenszel rate ratio is used to calculate incidence rate ratio and its 95% confidence interval (CI). RESULTS: Compared to districts of which no area fell within 300 m of high-voltage power lines, districts in which at least 50% of the area fell within 300 m of high-voltage power lines demonstrated an increased risk (incidence rate ratio: 2.2; 95% CI: 0.5-9.0). The association was strengthened for homes in which patients had resided for the longest interval of their lives (incidence rate ratio: 3.4; 95% CI: 0.9-13.2). Point-in-time measurements showed no increase in magnetic field levels for patient homes in districts near the lines. CONCLUSION: An increased, albeit nonsignificant, risk of childhood hematological malignancies associated with residential proximity to high-voltage power lines warrants further investigations.

Adolescent↗
PubMed2005

Reversible hearing loss associated with high-voltage electric shock.

Hearing loss associated with high-voltage electric shock is a rare entity and minimal information is available in the current literature about this condition. To our knowledge, this article represents the first case report in the literature of improvement in sensorineural hearing loss sustained due to a high-voltage electric shock. A case report of a patient who incurred various otologic problems, including hearing loss and tinnitus, is presented. An improvement in hearing loss and tinnitus was observed in the subsequent follow up after one month. Audiological findings and possible pathophysiology of hearing loss are discussed. We recommend that further studies be done to investigate the incidence, severity and pathophysiology of hearing loss in such cases.

Accidents, Occupational↗
PubMed1994

Effect of narrow, pulsed high voltages on bacterial viability.

BACKGROUND AND PURPOSE: High-voltage pulsed current (HVPC) has been used to promote the healing of decubitus ulcers and surgical wounds. The benefits of HVPC are thought to include an antimicrobial action. This study was undertaken to explore the development of an in vitro system for the systematic evaluation of the effects of HVPC. METHODS: Using agarose-based media, the system allows for examination of the direct effect of HVPC on microorganisms as well as exploration of the possible in situ generation of bacteriostatic or bactericidal factors by the action of HVPC on constituents of the media. The solid media also allow characterization of the spatial extent of the current's effects such as changes in temperature or pH. The system was used to examine the effects of HVPC on four different species of bacteria: Escherichia coli, Klebsiella, Pseudomonas aeruginosa, and Staphylococcus aureus. RESULTS: Both direct and indirect bactericidal effects were observed at either the positive or negative electrode, or both, for each of the organisms, although zones of inhibition varied. Temperature and pH were examined as possible mechanisms for the indirect effect. Temperature changes observed during the application of HVPC were minimal and did not contribute to the antimicrobial effect. Extreme pH changes did not appear to be the major cause of the indirect effect because the zones of inhibition observed were generally larger than the zones of extremely acid or basic pHs. CONCLUSION AND DISCUSSION: High-voltage pulsed current produced antimicrobial effects in this in vitro study. Additional studies are needed to elucidate the mechanisms and to determine whether the mechanisms occur in vivo.

Bacterial Infections↗
PubMed1998

Histamine modulates high-voltage-activated calcium channels in neurons dissociated from the rat tuberomammillary nucleus.

The effects of histamine on high-voltage-activated Ca2+ channels in the histaminergic neurons acutely dissociated from the rat tuberomammillary nucleus were investigated in the nystatin-perforated patch recording mode under voltage-clamp conditions. Histamine suppressed the high-voltage-activated Ca2+ channel currents in neurons which were positive for histidine decarboxylase with immunocytochemistry. The half-maximum inhibitory concentration and maximum inhibition were 2.6 x 10(-7) M and 16.6+/-1.90%, respectively. An H3 receptor agonist, R(-)-alpha-methylhistamine, mimicked the response to histamine, and thioperamide, an H3 receptor antagonist, inhibited the response to histamine. On the other hand, neither 2-methylhistamine, an H1 receptor agonist, nor dimaprit, an H2 receptor agonist, had a significant effect on the Ca2+ channel currents. Pretreatment with pertussis toxin blocked the inhibitory effect of histamine on Ca2+ channels, suggesting the involvement of Gi/Go proteins in the action of histamine. Omega-conotoxin-GVIA, omega-agatoxin-IVA, nicardipine, and omega-conotoxin-MVIIC blocked the high-voltage-activated Ca2+ channel currents by 15.6, 4.3, 27.1, and 31.2% of the total current, respectively, suggesting the existence of N-, P-, L-, and Q-type Ca2+ channels. A current that was insensitive to these blockers was also found. This residual current, "R-type", was completely suppressed by the addition of 200 microM Cd2+. Histamine significantly inhibited both the N- and P-type current components among these five types of Ca2+ channel currents. We concluded that histamine suppresses the N- and P-type Ca2+ channels in histaminergic neurons through an H3 receptor which is linked to a pertussis toxin-sensitive G-protein.

Animals↗
PubMed2003

Cool-Water Immersion and High-Voltage Electric Stimulation Curb Edema Formation in Rats.

OBJECTIVE: Although cryotherapy and high-voltage electric stimulation, both alone and in combination, are commonly applied to curb acute edema, little evidence from randomized controlled studies supports these procedures. Our purpose was to examine the effects of cool-water immersion (CWI) at 12.8 degrees C (55 degrees F), cathodal high-voltage pulsed current (CHVPC) at 120 pulses per second and 90% of visible motor threshold, and the combination of CWI and CHVPC (CWI + CHVPC) on edema formation after impact injury to the hind limbs of rats. DESIGN AND SETTING: Both feet of 34 rats were traumatized after hind-limb volumes were determined. Animals were randomly assigned to 1 of 3 groups: CWI (n = 10), CHVPC (n = 10), or CWI + CHVPC (n = 14). One randomly selected hind limb of each rat was exposed to four 30-minute treatments, interspersed with four 30-minute rest periods beginning immediately after posttraumatic limb volumes were determined. Contralateral limbs served as controls. Limbs remained dependent during all treatments, rest periods, and volumetric measurements. SUBJECTS: We used 34 anesthetized Zucker Lean rats in this study. MEASUREMENTS: We measured limb volumes immediately before and after trauma and after each of 4 treatment and rest periods. RESULTS: Volumes of treated limbs of all 3 experimental groups were smaller (P <.05) than those of untreated limbs. No treatment was more effective than another. CONCLUSIONS: Cool-water immersion, cathodal high-voltage electric stimulation, and simultaneous application of these treatments were effective in curbing edema after blunt injury. Combining CWI and CHVPC was not more effective than either CWI or CHVPC alone.

Journal Article↗
PubMed1988

Acceleration of wound healing with high voltage, monophasic, pulsed current.

The purpose of this study was to determine whether high voltage electrical stimulation accelerates the rate of healing of dermal ulcers. Sixteen patients with stage IV decubitis ulcers, ranging in age from 20 to 89 years, participated in the study. The patients were assigned randomly to either a Treatment Group (n = 9) or a Control Group (n = 7). Patients in the Treatment Group received daily electrical stimulation from a commercial high voltage generator. Patients in the Control Group had the electrodes applied daily but received no stimulation. The ulcers of patients in the Treatment Group healed at a mean rate of 44.8% a week and healed 100% over a mean period of 7.3 weeks. The ulcers of patients in the Control Group increased in area an average of 11.6% a week and increased 28.9% over a mean period of 7.4 weeks. The results of this study suggest that high voltage stimulation accelerates the healing rate of stage IV decubitis ulcers in human subjects.

Adult↗
PubMed1999

Changes in skin structure and electrical properties following high voltage exposure.

Human skin experiences extensive alterations when exposed to a strong electric field. In high voltage electric shocks, tissues in the current path undergo large-scale changes; the stratum corneum (SC), the outermost layer of the skin, loses its barrier function against ionic transport. The primary mechanism of electric field interaction with the skin is the creation of aqueous pathways, which increase the permeability of the skin to ions and macromolecules. Changes in skin structure and electrical properties were characterized by measuring the transport of fluorescent molecules in an in vitro preparation of human cadaver skin in a permeation chamber. Application of high voltage pulses (Uskia > 150 V, tau pulse = 1 ms) decreased the skin resistance per unit area by three orders of magnitude from its initial value of 100 k omega-cm-2. The resistance reached a quasi-steady state after about 20 pulses. After the cessation of pulsing, Rskin recovered immediately to about 4 k omega-cm-2 and remained low for 2 h thereafter. Transport of fluorescent molecules by high voltage pulses occurs in highly localized transport regions (LTRs), with diameters not exceeding 100 microns for short pulses (tau pulse < 5 ms).

Electric Impedance↗
PubMedDate not supplied

Normative values for high voltage electrical stimulation across the brachial plexus.

OBJECTIVES: To obtain normative values for High Voltage Electrical Stimulation across the brachial plexus between Erb's point, C8 root and T1 root. A case study of probable true thoracic outlet syndrome is used to illustrate the usefulness of the method. METHODS: 22 patients were tested for use in normative date pool with complaints unrelated to the ulnar nerve, the majority of which were pure carpal tunnel syndrome. High voltage stimulation was performed at Erb's point, C8 root and T1 root. Recording was from the abductor digit minimi muscle. RESULTS: Upper limit for absolute latencies were 13.9 ms, 14.5 ms and 14.5 ms for Erb's point, C8 root and T1 root stimulation respectively. Corresponding lower limits of amplitude were 4.8 mV, 3.4 mV and 2.9 mV. Upper limits for interpeak latencies were 1.4 ms and 1.2 ms for C8 to Erb's point and T1 to Erb's point respectively. In a case of true thoracic outlet syndrome, the symptomatic side revealed prolonged interpeak and absolute latencies. The asymptomatic side remained within normal limits. CONCLUSION: Normative values for high voltage stimulation across the brachial plexus are useful in cases of suspected compression in this proximal location of the upper limb.

Adolescent↗
PubMed2004

[Enhancing the healing of venous crural ulceration after surgical treatment with high voltage stimulation].

The objective of the study was to evaluate the influence of a high voltage stimulation on the process of healing of crural ulcerations after causal surgical treatment. Two comparative groups of patients, A and B, were made at random from patients with venous crural ulcers, who had been earlier operated by Babcock' method. The group A consisted of 12, and the group B--13 patients. The patients in two comparative groups were treated pharmacologically. Ulcerations at the patients in the group A were additionally treated with the high voltage stimulation. Changes of the area, length, width, and volume of the tissue defect after the high voltage stimulation were assessed. Weekly changes of the above parameters were determined as well. After the therapy there was a statistically significant decrease of the total and pus-covered areas, length, width and volume of ulcerations in both groups, while there was no statistically significant difference--except pus-covered areas--between the groups observed. Only the reduction of pus-covered area in the group A was statistically significantly faster than in the group B.

Adult↗
PubMed1988

High-precision tilt stage for the high-voltage electron microscope.

The high-voltage electron microscope is used to study thick samples (0.25 to several micrometers) to obtain three-dimensional information at ultrastructural resolution. Three-dimensional image reconstructions are often employed to extract, process and display this information. The sets of images used to form reconstructions must be recorded for precisely known specimen-beam orientations, especially if tomographic methods are employed. The design and operation of a precision (+/- 0.06 degrees) single-tilt stage to support this type of imaging is reported. All motions including two translations, height adjustment and tilting are accomplished via a single objective lens entry port. The specimen rod is supported on two rubber gaskets for vibration isolation, and motorized precision micrometers with encoder readouts for position monitoring drive the motions. The stage is stable to 0.6 nm for at least 16 s and is capable of tilt angles of +/- 70 degrees.

Microscopy, Electron↗
PubMedDate not supplied

Separation of nucleotides by high-voltage capillary electrophoresis.

A new separation method using high-voltage capillary electrophoresis was applied to the analysis of several nucleotides. This system consisted of a micro-bore glass capillary column of 80-micron i.d., a high-voltage power supply, and a uv detector set at 254 nm. Seven nucleotides (cyclic AMP, AMP, ADP, ATP, GMP, GDP, and GTP) were separated completely from each other in 0.02 M phosphate buffer (pH 7) containing 0.5% ethylene glycol by applying about 150 V/cm. The theoretical plate number for AMP was nearly 45,000. A good separation of nucleotides in biological samples of rat blood, liver, and kidney was attained under the same conditions as above. Concentrations of nucleotides in these biological samples were measured by using pyridoxamine as an internal standard.

Animals↗
PubMed2000

Muscle transfection by electroporation with high-voltage and short-pulse currents provides high-level and long-lasting gene expression.

Gene transfer into muscle by electroporation with low-voltage and long-pulse (LV/LP, 100 V/50 msec) currents was shown to be more efficient than simple intramuscular DNA injection. Nevertheless, transgene expression declined from day 7 and only reached 10% of the maximum 3 weeks after electroporation. We have optimized electroporation conditions including voltage, pulse number, and the amount of injected luciferase-encoding plasmid DNA in the tibialis anterior muscle. Using high-voltage and short-pulse (HV/SP, 900 V/100 microsec) currents, we observed an average 500-fold increase in luciferase expression, in comparison with nonelectroporated muscle. Moreover, sustained and long-lasting gene expression was observed for at least 6 months. When we compared HV/SP currents with LV/LP currents, luciferase expression was similar 24 hr after electroporation. One month later, whereas luciferase expression was stable in muscle electroporated with HV/SP currents, it decreased 600-fold in muscle electroporated with LV/LP currents. In conclusion, electroporation with high-voltage and short-pulse currents provides high-level and long-lasting gene expression in muscle.

Animals↗
PubMed1998

Digital radiology using active matrix readout of amorphous selenium: detectors with high voltage protection.

A flat-panel x-ray imaging detector is being investigated for digital radiography and fluoroscopy. The detector uses a layer of amorphous selenium (a-Se) to convert x rays to a charge image, which is then electronically read out with a two-dimensional array of thin film transistors (TFTs). In order to sensitize the a-Se layer to x rays, a high voltage (of the order of several thousand volts) is applied to its top surface. The TFTs, which are at the bottom surface of the a-Se layer, are not subjected to any high voltage under normal radiological operational conditions since the pixel potential is < 10 V. However under a fault condition where these two events occur simultaneously: (1) suspended detector scan; and (2) an x-ray exposure more than ten times higher than normal, the voltage on the TFTs could rise to a damaging value. This paper describes a method for protecting the TFTs from high voltage damage under this fault condition. It employs a dual-gate TFT structure, one gate is for scanning control and the other is connected to the pixel electrode for high voltage protection. Before the pixel potential reaches a damaging value, the protection gate turns on the TFT automatically and drains excess charge away from the pixel thus providing a safe pixel saturation potential. In this paper, the characteristic curves of dual-gate TFTs are studied both theoretically and experimentally. The pixel x-ray response for imaging detectors with high voltage protection are predicted, and it is shown that with practical TFT designs the detector can provide a safe pixel saturation potential as well as satisfy the dynamic range required for diagnostic x-ray imaging applications.

Equipment Design↗
PubMed1990

The effects of a single high voltage electrical stimulation with an anticancer drug on in vivo growing malignant tumors.

Giving a high voltage electrical stimulation (5 kv/cm, 2 msec) under bleomycin administration (5 mg/body, im) resulted in a significant size decrease of subcutaneously inoculated AH-109A hepatocellular carcinomas in Donryu rats. The tumor size decreased to an average 17 per cent of the initial mass 4 days after the treatment and the average survival period was extended to almost 200 per cent of that of the control. However, neither high voltage electrical stimulation nor bleomycin administration alone demonstrated an anticancer effect. It was thus concluded that the concomitant use of a high voltage electrical stimulation and an anticancer drug has the potential to be effectively applied in cancer treatment.

Animals↗
PubMedDate not supplied

Eleven-year-old male with high-voltage electrical injury and premature ventricular contractions.

We present a case of a boy with potential high-voltage electrical injury. The patient sustained electrical injuries after his kite became entangled in a high-power electrical line. He presented to the emergency department with minor external electrical burns and frequent premature ventricular contractions (PVCs). The patient's clinical course is outlined. A discussion of the epidemiology of high-voltage electrical injury in children and the clinical management of electrical-injury-induced cardiac complications is provided. Although cardiac abnormalities are found in a significant proportion of high-voltage electrical injuries, the vast majority are evident within 12 h, resolve spontaneously within a few days, and cause little or no long-term sequelae. A small proportion of normal children have clinically benign PVCs.

Child↗
PubMed2002

A high voltage RF oscillator for driving multipole ion guides.

A high voltage RF oscillator circuit has been designed and constructed for driving multipole ion guides. The circuit is tunable from 500 kHz to 1.5 MHz by changing a capacitor and provides 0-1000 V(p-p) that is controlled by a 0-10 V input using a negative feedback circuit. This inexpensive circuit uses a set of high voltage transistors oscillating in tandem and does not require tuning of the resonance drive frequency as the oscillator automatically resonates at the (LC)(-1/2) frequency. Matrix-assisted laser desorption/ionization-Fourier transform mass spectrometry (MALDI-FTMS) mass spectra were acquired using this tunable RF oscillator circuit to allow transmission of protein ions in the 8.5-39 kDa range through the quadrupole ion guide from the ion source to the mass analyzer.

Electronics↗
PubMed1987

Effects of a high-voltage electrical impulse and an anticancer drug on in vivo growing tumors.

Application of a high-voltage electrical impulse (5 kV/cm, 2 msec) after bleomycin administration resulted in a significant size decrease of subcutaneously inoculated AH-109A hepatocellular carcinoma in Donryu rats. The tumor size decreased to an average of 17% of the initial mass 4 days after the treatment. Neither the high-voltage electrical impulse nor bleomycin administration alone showed an inhibitory effect on the tumor growth. It was concluded that the concomitant use of a high-voltage electrical impulse and an anticancer drug has the potential to be applicable for cancer treatment.

Animals↗
PubMed1997

Risks of leukaemia among residents close to high voltage transmission electric lines.

OBJECTIVES: To reassess the risk of leukaemia associated with residential exposure near high voltage transmission electric lines of 49 kV and above in view of the recent publications. METHODS: Through a review of papers considering the risk of leukaemia among people living near high voltage transmission lines, the combined risks of leukaemia were calculated for distances < or = 50 m and < or = 25 m and for exposures at 2 mG, 3 mG, 4 mG, and 10 mG. RESULTS: The combined analysis of the contributive studies indicated an estimate of risk (odds ratio (OR)) for exposure > or = 2 mG of 1.3, 95% confidence interval (95%CI) 1.0 to 1.7. The ORs increased with exposures at 3 mG, 4 mG, and 10 mG. The risks were also increased for distances of 50 and 25 m from the lines. CONCLUSIONS: This meta-analysis tends to confirm the presence of an association between exposure to magnetic fields and leukaemia among people who reside in the vicinity of high voltage transmission electric lines of > or = 49 kV. There is consistency across studies. Measures of exposure used in the studies were either distance from the lines or calculated fields estimated from pertinent line features. The results apply to adults as well as to children.

Adult↗