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PubMed1999

Therapeutic resistance: characterization and inactivation by specific antiserum of a putative protein family produced by tumour cells.

A multitherapy resistance (MTR) factor produced by Cloudman S91 mouse melanoma cells rescues a responsive cell line after gamma-irradiation, short wavelength ultraviolet light, mitomycin C, vinblastine and actinomycin D. A similar activity with respect to ionizing radiation is now shown to be produced by human melanoma cells and by both human and mouse breast cancer cells but not by five normal cell lines. In these studies, the factor produced in serum-free conditioned medium (SFCM) by Cloudman S91/I3 cells is further characterized. Its activity in a clonogenic assay using related Cloudman S91/amel cells is destroyed by trypsin but not by DNase and is stable for at least 8 days at a variety of temperatures including 37 degrees C. Molecules greater than 30 kDa from SFCM collected from S91/I3 cells were concentrated and separated by preparative zonal electrophoresis (PZE). Bioactivity was present in both the cathode- and the anode-running fractions. The active acidic (anode) fractions were analysed by preparative isoelectric focusing. Bioactivity was present between pI 3.5 and 4.2. These PZE fractions were also used to immunize two rabbits, both of which produced antiserum that abrogated the bioactivity of SFCM and of the PZE cathode fractions. Antiserum also decreased the survival of irradiated S91/I3 producer cells that do not respond to SFCM but nonetheless must require MTR proteins for the expression of radiation resistance. These studies present a model for the production of rescue factors by non-clonogenic tumour cells that may persist in some tumours for considerable periods of time.

Amino Acid Transport Systems, Neutral↗
PubMed1999

Reduce risk of inducing spatial disorientation using physiologically compatible ground lighting.

Spatial disorientation that occurs while landing aircraft during night operations may result in accidents and fatalities which are often classified as secondary to "pilot error." It has now been determined that the use of "expedient" lights, which include flares, flashlights, automobile headlights, etc., can induce spatial disorientation in pilots. The element that contributes to induction of spatial disorientation is the "point source of light" provided by these lights. Impingement on the retina of concentrated photon emissions, as supplied by incandescent (filament) lamps, flares, etc., produces an "after image," such as occurs when one briefly looks into the sun. The "after image" is caused by the time lag required for reconstitution of the neurohumoral transmitter substances in the retinal rods and cones. Pilots who develop "after images" during the final stage of landing a helicopter at night are predisposed to experiencing spatial disorientation, leading to aircraft mishaps. In contrast to flares or incandescent light sources, cold cathode lamps lack a "point source" of light emission, do not create an "after image," and are ideal to use in night landing operations. Cold cathode lights operating in the range of 512 nm (blue-green) are thought to be the most physiologically efficient color to use for night landing operations. Light sources in this nanometer range provide maximum visibility and safety for the pilot during landing operations under all environmental conditions.

Accidents, Aviation↗
PubMed1975

Direct-current stimulation of non-union and congenital pseudarthrosis. Exploration of its clinical application.

Based on the response of bone to electrical current in previous studies, an exploratory clinical study of the effect of electrical current on non-union and congenital pseudarthrosis was performed. Constant direct current of ten to twenty microamperes was applied to twenty-four non-unions and five congenital pseudarthroses. Complete union occurred in fifteen non-unions and in one congenital pseudarthrosis. A single cathode delivering ten microamperes seemed sufficient to heal non-union in small bones, but multiple cathodes each delivering twenty microamperes appeared to be required to heal non-union in the tibia and femur. As the technique was refined, the percentage of successes increased. While these preliminary results appear promising, further laboratory and clinical experiments are required to define the true role of electrical stimulation in clinical practice.

Adolescent↗
PubMed1975

Stimulation of Fracture Healing by Pacemaker in Rabbits.201S.

An und-splaced fracture of each fibula was produced in 20 rabbits. Into the fracture of the right fibula, a cathode was inserted, which delivered 15 microamperes of galvanic current for more than one week. The source of current was 5v small transistor batteries which acted like a pacemaker. This stimulated healing of the fracture for 15 days. The left fibula fractures were used as controls. Both fibulae were studied roentgenographically and microscopically. This experiment suggested that galvanic current with a cathode placed in the fracture gap stimulated fracture healing.

Animals↗
PubMed2000

Experimental low-level direct current therapy in liver metastases: influence of polarity and current dose.

Several authors recently reported on the successful local treatment of malignant disease with low-level direct current therapy. However, antitumoral effects in colorectal metastases has not been investigated experimentally. The aim of the present study was to assess the effectiveness of this therapy and the influence of polarity and current dose. Colorectal metastases were established in BD IX rats by the injection of colon cancer cells under the liver capsule. After three weeks, the liver tumor volumes were determined by magnetic resonance imaging of the liver. Low-level direct current therapy was applied via five platinum electrodes. Four different applications were used: 60 C/cm(3), anode at the center; 60 C/cm(3), cathode at the center; 80 C/cm(3), anode at the center; and 80 C/cm(3), cathode at the center. In the control group, five electrodes were placed without applying any direct current. All animals were sacrificed on postoperative day 7. Liver metastases were histologically examined for vital tumor cells. Statistical analysis was performed with chi(2)-test. The mean initial tumor diameter before treatment was 3.6 +/- 1.4 mm (volume: 25.2 +/- 9.7 mm(3)). Histological examination of the removed livers revealed significant destruction of the metastases with localized necroses in all treatment groups; 37% had a complete response rate and 63% a partial response rate. There were no significant necroses in the control group (P < 0.0001). The best treatment results were obtained in the group with an anode at the center and a current dose of 80 C/cm(3). Direct current therapy offers a new and safe method for the local treatment of liver metastases. We were able to observe that tumor damage is related to current dose but not to the polarity of the central electrode.

Animals↗
PubMed1979

Isolation and renal localisation of urokinase.

Physico-chemical characteristics of urokinase in urine were studied by immunological and chemical methods. By agar zone electrophoresis, commercial urokinase preparations could be separated into an anodic and cathodic fraction. The latter reacted with urokinase antibodies with two precipitation bands. Band I displayed the major part of urokinase activity and migrated as a beta-globulin with a molecular weight of 32,000 daltons. Band II showed immunological identity with human serum, human albumin, alpha-2-macroglobulin and alpha-2-HS-glycoprotein. The specific activity of the cathodic fractions was up to 80,000 ploug units/mg protein. The ratio esterase/fibrinolytic activity did not change during the purification procedure. Further purification of the fractions with higher specific activity by affinity chromatography was unable to eliminate material cross reacting with human antisera (Band II). These findings permit the conclusion, that urokinase activity in urine is not confined to a homogeneous protein fraction. Activity is found both in a low molecular weight fraction and in a high molecular weight complex which contains serum proteins. These cannot be removed by exhaustive purification procedures and may play an important role in stabilizing and/or protecting urinary urokinase against proteolytic degradation. With Todd's technique diffuse fibrinolytic activity could be demonstrated in the kidney in the iuxtamedullary border region, (venae arcuatae, venae interlobulares, vasa recta) and in the epithelium of the calyces. Urokinase activity was specifically blocked by highly purified urokinase antibodies and could thus be distinguished from nonspecific proteolytic activity. The topographic relationship to medulla and uroepithelium may point to a role of urokinase in maintaining patency in slow flow systems.

Endopeptidases↗
PubMed1975

The effects of minute direct electrical currents on cultured chick embryo trigeminal ganglia.

The effects of low levels of electric current were determined on organ cultures of 6- to 19-day-old chick embryo trigeminal ganglia. Current levels ranged from 0.00115 to 11.5 nA/mm2; the time of electrical treatment varied from 2 h to 96 h. Low levels of electricity were found to have at least three major effects on this system of mixed cellular types: (1) Outgrowth of nerve fibers from the explant was enriched. This resulted in a greater number of fibers which were longer and more highly branched than those in control cultures. (2) Survival of neurons within the original explanted ganglion was enchanced by treatment with electricity. The presence of healthy neurons was found in 93.1% of the treated cultures and in 53.5% of untreated cultures. (3) Neurons, fibers and non-neural cells were stimulated to grow in the direction of the cathode. The rate of cathodal migration was calculated to be 0.1 mm/h (2.4 mm/day) in an explant from 12-day-old embryo. No differences were observed between surviving treated and control cultures in histochemical tests for acetycholinesterase. A similarity between the action of low levels of electrical current and nerve growth factor (NGF) is suggested.

Acetylcholinesterase↗
PubMed1975

[Dependence of various antigen formation of Proteus mirabilis strain 1095/67 growing on minimal nutrient media].

Proteus mirabilis strain 1095/67 has been cultivated in surface culture on different minimal media, which were composed either of single amino acids or combinations of several amino acids without or with stepwise addition of other C-sources up to the complete medium. We found a direct dependence of the formation of the various antigens (moving to the cathode, to the anode, or not moving) on the composition of the medium. Certain amino acids (Ala, Glu, Asp. Ser) elicit only parts of the antigenic spectrum formed in complete medium, but enrich special antigens. With only 2 amino acids (Ala and Glu) and the vitamins thiamine, pyridoxal, and niacine in the anorganic basic medium the complete antigenic spectrum can be formed. We have shown that the composition of the cell wall varies with the composition of the culture medium. In shaked cultures we found serine to be essential for the production of the antigen moving to the cathode and the thermolabile antigene moving to the anode (ATA), niacine to be of fundamental importance in the biosynthesis of all antigens. Already under very limited supply of nutrients ATA, common to all gram-negative bacteria, is formed and, therefore, it seems to be a very basic cell wall component.

Amino Acids↗
PubMedDate not supplied

Voltammetric determination of benazepril and ramipril in dosage forms and biological fluids through nitrosation.

A simple and highly sensitive voltammetric method was developed for the determination of benazepril (I) and ramipril (II). The compounds were treated with nitrous acid, and the cathodic current produced by the resulting nitroso derivatives was measured. The voltammetric behavior was studied by adopting direct current (DCt), differential pulse (DPP), and alternating current (ACt) polarography. Both compounds produced well-defined, diffusion-controlled cathodic waves over the whole pH range in Britton-Robinson buffers (BRb). At pH 3 and 5, the values of diffusion-current constants (Id), were 5.90 +/- 0.40 and 6.66 +/- 0.61 for I and II, respectively. The current concentration plots for I were rectilinear over the range of 1.5-40 and 0.1-30 microg/mL in the DCt and DPP modes, respectively; for II, the range was 2-30 and 0.1-20 microg/mL in the DCt and DPP modes, respectively. The minimum detectabilities (S/N = 2) were 0.015 microg/mL (about 3.25 x 10(-8)M) and 0.012 microg/mL (about 2.88 x 10(-8)M) for I and II, respectively, adopting the DPP mode. Results obtained for the proposed method when applied to the determination of both compounds in dosage forms were in good agreement with those obtained using reference methods. Hydrochlorthiazide, which is frequently co-formulated with these drugs, did not interfere with the assay. The method was also applied to the determination of benazepril in spiked human urine and plasma. The percentage recoveries adopting the DPP mode were 96.2 +/- 1.21 and 95.7 +/- 1.61, respectively.

Angiotensin-Converting Enzyme Inhibitors↗
PubMedDate not supplied

The removal of low level inorganics via electrogenerated hydrogen peroxide in the presence of catalytic amounts of Fe2+.

Low level phosphites and hypophosphites were completely converted into phosphates, via hydrogen peroxide generated by cathodic reduction of oxygen in acidic aqueous medium at a reticulated vitreous carbon electrode, in the presence of little amounts of Fe2+. The contemporary regeneration of Fe2+ by cathodic reduction of Fe3+, produced by the well known Fenton reaction, furnishes an excellent way to continuously produce little amounts of the Fenton reactive and, as a consequence, of the powerful oxidant hydroxyl radical HO.. The best conditions for the complete removal of phosphorous as phosphites and hypophosphites are reported.

Electrolysis↗
PubMedDate not supplied

[X-ray tubes with ionic indemnification of negative space electronic charge].

How to increase anode current in the fine-focus diagnostic X-ray tubes (XTs) is analyzed. It has been found that there are new three-class XTs that have advantages of both ionic and electronic tubes. The specific feature of the new class XTs is the gaseous atmosphere available in the working volume. Ionizing the gaseous atmosphere with a emission electron flow in the path from the cathode to the anode yields a dot volumetric positively charged ion grid that closely approaches the cathode and can pay a big bonus in anode current output.

Humans↗
PubMed2002

Liver electrolysis: pH can reliably monitor the extent of hepatic ablation in pigs.

Electrolysis is a method of tissue ablation that creates chemical species and a pH gradient in response to direct current. Initial studies of electrolysis in animal models and humans have shown that it is a safe, predictable and effective process for destroying normal and tumour-bearing liver in a linear, dose-dependent manner. Presently, the amount of current that is applied (in coulombs) has to be calculated using historical data, with inherent inaccuracy. The present study tested whether pH could be used as a real-time monitor in order to predict more accurately the extent of necrosis. A total of 70 electrolytic lesions were created in 14 pigs, with pH monitoring of the lesion edge. The normal range of pH values was 6.5-8.7. A pH of less than 6 (at the anode) or more than 9 (at the cathode) reflected total cellular necrosis. When a pH value was recorded between 6.0 and 6.5 at the anode or between 8.7 and 9.0 at the cathode, the presence of necrosis was variable. In conclusion, during electrolytic ablation, pH measurement can monitor the extent of the induced necrosis.

Animals↗
PubMed2002

Removal of copper from a copper sulphate solution using an ultrasonic-electrolysis process.

The application of ultrasonic-electrolysis process for the removal of copper is studied. In the ultrasonic field cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution. Thus increases metal deposition on the cathode surface. The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution.

Antidotes↗
PubMed2002

Repassivation of a high chromium stainless steel orthopaedic alloy.

The repassivation of Ortron90, a high chromium stainless steel alloy, was studied to assess the effect of passive layer removal on corrosion levels. Cathodic dissolution of the passive layer followed by potentiostatic experiments within the passive region were employed to study the repassivation process. The scratch method, carried out for comparison purposes, yielded current densities similar to those obtained by cathodic dissolution. The detailed analysis of the slopes of plots of log I/log t indicated that the repassivation did not follow any of the existing growth models. It also suggested that the slope depended on the extent of repassivation and reached a minimum when three to five monolayers of oxide were completed. The virtual potentiodynamic plots suggested the presence of some form of protective layer within 5-10 seconds and the change in open circuit potential vs time indicated that the passive layer present after 10 seconds of repassivation continued to evolve for about 1000 to 1500 seconds possibly representing a transition between two different forms such as oxide and a oxyhydroxides. Estimation of the effect of localized removal of passive layer on the corrosion indicated a dramatic increase in local corrosion density. These results show that a fast repassivation rate is an important requirement for biocompatibility of alloys used to manufacture dental and orthopaedic devices.

Biocompatible Materials↗
PubMed1976

Determination of arsenic and selenium in foods by electroanalytical techniques.

Arsenic and selsnium are determined in foods be differential pulse polarography and cathodic stripping voltammetry. The sample is digested with nitric acid and magnesium nitrate and then dissolved in dilute hydrochloric acid. An aliquot is removed, the arsenic is chemically reduced to the trivalent state, and interferences are removed by ion exchange before polarography. Selenium is determined in a second aliquot by cathodic stripping voltammetry. Recoveries for both elements in several foods were from 90 to 110%. The relative standard deviations for arsenic at 5 ppm and selenium at 0.48 ppm were 5.8 and 7.3%, respectively.

Arsenic↗
PubMed2003

Irradiation of intense characteristic x-rays from weakly ionized linear molybdenum plasma.

In the plasma flash x-ray generator, a high-voltage main condenser of approximately 200 nF is charged up to 55 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to a rod molybdenum target of 2.0 mm in diameter by the electric field in the x-ray tube, weakly ionized linear plasma, which consists of molybdenum ions and electrons, forms by target evaporation. At a charging voltage of 55 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities increased. The K lines were quite sharp and intense, and hardly any bremsstrahlung rays were detected. The x-ray pulse widths were approximately 700 ns, and the time-integrated x-ray intensity had a value of approximately 35 micro C/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV.

Electrodes↗
PubMedDate not supplied

[The phenomenon of antigenic defectiveness in naturally circulating strains of the tick-borne encephalitis virus and its possible connection to seronegative forms of the disease].

Ten strains of tick-borne encephalitis (TBE) virus isolated from single specimens of I. persulcatus ticks were studied. The strains were divided into antigenically complete (AC) and antigenically defective (AD), depending on the presence or absence of some virus antigens in concentrated virus preparations, characteristics in rocket immune electrophoresis (RIEP), rate and intensity of humoral immune response in monkeys and rabbits, and plaque size in SPEV cell culture. The AC-strain markers include high activities of precipitating, hemagglutinating (HA), and complement-fixing (CF) antigens, formation of precipitates moving in rocket shape towards anode and cathode in RIEP, rapid development of antihemagglutinins and virus-neutralizing antibodies, large plaques (3-5 mm). The AD variants are characterized by the lack of HA and precipitating activity, low titres of CF antigen, slow and poor immune response, the lack of cathode precipitate "rocket", very small plaques. The antigenic defectiveness is transitory and shows in early passages; after 10-11 passages in SPEV cell cultures or in white mice, transformation AD----AC occurs. A transformed strain is neutralized, like standard TBE strains, by blood sera of a typical patient with poliomyelitis-like form of TBE. Examinations of blood sera from the population of an endemic zone (Yaroslavl Province) and 67 TBE patients (Kurgan Province) demonstrated the association of AC and AD variants with the formation of immune portion of the population and TBE etiology. Cases of the disease confirmed by seroconversion in HI with commercial diagnosticum are associated with AC variants, whereas AD variants are associated with those TBE cases which are difficult to diagnose using the commercial diagnosticum.

Animals↗
PubMed2003

[Linkage of genes responsible for sex determination and expression of a sperm-specific isozyme of glucose-6-phosphate isomerase in the polychaete Polydora brevipalpa].

In Polydora brevipalpa (Polychaeta, Spionidae), an unusual electrophoretic pattern of glucose-6-phosphate isomerase (GPI) which is determined by a single GPI gene locus and represented by two isozymes (GPI-1 and GPI-2) has been revealed. The anode isozyme (GPI-1) was detected in both males and females, whereas the cathode enzyme GPI-2 appears in males and results from alternative splicing of the pre-mRNA transcripts. In males, GPI-2 was shown to express only in sperm. The results obtained suggest that the genes responsible for sex determination and expression of the alternative isozyme GPI-2 are tightly linked. However, rare recombination events between these genes produce reciprocal deviant GPI phenotypes in males (GPI-2 is absent) and females (GPI-2 is present). In the sample of 376 individuals (202 males and 174 females) six recombinant males and six recombinant females were found, which ratio is in good agreement with the expected 1:1 ratio. Recombinant males of different genotypes at the GPI locus were also found. This indicates the absence of negative selection against all genotypes of the locus, except those carrying the unique allele that controls the cathode allozyme GPI-1. The results obtained suggest genetic sex determination in P. brevipalpa. Based on the fact that genetic sex determination is also characteristic of other species of the genus Polydora, which diverged independently during several million years, and taking into account that only six recombination events occurred in the history of 376 P. brevipalpa genomes examined, the conclusion is made that the gene responsible for sex determination and that responsible for the expression of the alternative GPI-2 isozyme are tightly linked.

Animals↗