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PubMed1999

Epidermal growth factor receptor relocalization and kinase activity are necessary for directional migration of keratinocytes in DC electric fields.

Human keratinocytes migrate towards the negative pole in DC electric fields of physiological strength. This directional migration is promoted by epidermal growth factor (EGF). To investigate how EGF and its receptor (EGFR) regulate this directionality, we first examined the effect of protein tyrosine kinase inhibitors, including PD158780, a specific inhibitor for EGFR, on this response. At low concentrations, PD158780 inhibited keratinocyte migration directionality, but not the rate of migration; at higher concentrations, it reduced the migration rate as well. The less specific inhibitors, genistein, lavendustin A and tyrphostin B46, reduced the migration rate, but did not affect migration directionality. These data suggest that inhibition of EGFR kinase activity alone reduces directed motility, and inhibition of multiple tyrosine kinases, including EGFR, reduces the cell migration rate. EGFR redistribution also correlates with directional migration. EGFR concentrated on the cathodal face of the cell as early as 5 minutes after exposure to electric fields. PD158780 abolished EGFR localization to the cathodal face. These data suggest that EGFR kinase activity and redistribution in the plasma membrane are required for the directional migration of keratinocytes in DC electric fields. This study provides the first insights into the mechanisms of directed cell migration in electric fields.

Cell Movement↗
PubMed1980

The effects of applied electric fields on Micrasterias. I. Morphogenesis and the pattern of cell wall deposition.

Applied electric fields of approximately 14 V/cm have profound effects on the morphogenesis of the unicellular green alga, Micrasterias denticulata. This field corresponds to a potential drop of 15-40 mV across lobes oriented perpendicular to the applied field. These lobes show a galvanotropism toward the cathode. Lobes growing parallel to the field are stunted to varying degrees, depending on their orientation. As shown by other investigators, most cell wall material is normally deposited at the tips of growing lobes. If, however, cell expansion is osmotically inhibited in electric fields, wall material also accumulates along the cathode-facing (CF) sides of lobes oriented perpendicular to the field. Similarly, in cells growing under the influence of an applied field, radioactively labelled glucose and the methyl groups from methionine are incorporated along the CF sides of lobes as well as the lobe tips. This is also true when the label is added immediately after cells are removed from the fields, indicating that the wall-depositing machinery itself has been temporarily altered by the field. These results demonstrate that applied electric fields can be a valuable tool in elucidating the mechanisms of growth localization in Micrasterias cells.

Cell Wall↗
PubMed1988

Studies on the nephrotoxicity of aminoglycoside antibiotics and protection from these effects. (5). Interaction of tobramycin with latamoxef in vitro.

Interaction of tobramycin (TOB) with latamoxef (LMOX) was studied in vitro. Solutions containing TOB alone, LMOX alone or both of these compounds in varying molar ratios (TOB:LMOX = 1:1, 1:2, 1:4 and 2:1) were incubated at 37 degrees C for 0.5, 1, 3 and 5 h after adjusting to pH 7.4. Aliquots sampled at a suitable time were subjected to paper electrophoresis (PE) and thin layer chromatography (TLC). In PE, the spots of TOB and LMOX were observed as single spots on the cathode and anode sides, respectively. However, the spot associated with TOB overlapped with that associated with LMOX on the cathode side when aliquots of the solution containing both TOB and LMOX were analyzed. It seemed that the degree of overlapping became stronger with an increase in incubation time, and there were no spots corresponding to TOB alone in the mixture of TOB-LMOX (1:4). TLC analysis showed that the spot of LMOX radiated fluorescence with Rf value 0.38. On the other hand, in the mixtures, there was a definite decrease in fluorescence of LMOX at the position of Rf value 0.38, compared with that of LMOX alone. Furthermore, the spot associated with LMOX, which overlapped with that associated with TOB, also appeared at the origin on the TLC plate. The ultraviolet spectrum of the mixture of TOB-LMOX (1:2) showed a decrease in the intensity of absorption of LMOX at 268 nm. These interactions between TOB and LMOX were also observed in rat serum and its filtrate in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Interaction between human tissue thromboplastin and human antithrombin III.

It is known that antithrombin III (ATIII) activity is inhibited by tissue thromboplastin (TP) in the presence of heparin. In our study on the mechanism of the inhibition, however, TP was found to inhibit ATIII activity even in the absence of heparin, indicating an interaction between ATIII and TP. We then studied effect of ATIII on the interaction between factor VII (FVII) and TP using FVII-depleted human plasma. When the mixture of FVII + ATIII + TP was incubated at 37 degrees C and mixed with FVII-depleted plasma, the interaction between FVII and TP was inhibited. Possible complex formation was examined by electrophoretic techniques. In the immunoelectrophoresis, ATIII shifted toward the cathode in the presence of TP and the substance which had changed the mobility of ATIII showed TP activity after zone electrophoresis. The results indicated that TP had shifted toward the anode due to ATIII while ATIII had shifted toward the cathode due to TP. In the immunoblotting analysis, ATIII was separated into several bands in the presence of TP. ATIII antigenicity was altered in the presence of both heparin and TP but not in the presence of TP alone. Our results strongly suggest that TP modulates ATIII activity in the initiation of the TP-mediated coagulation cascade and that in progressing coagulation ATIII participates in the inhibition of the coagulation cascade by blocking not only thrombin activity but also the interaction between TP and FVII.

Antithrombin III↗
PubMed2005

Evaluation of ferryl formation by electrocatalytic oxidation of alkene using luminol chemiluminescence.

Electrochemical formation of ferryl porphyrin was examined by electrocatalytic oxidation of alkene by measuring luminol chemiluminescence using a flow-injection method. Emission was observed both below the reduction potential of Fe(III)TMPyP (-0.08 V at pH 11, -0.02 V at pH 7 and 0.15 V at pH 3) and above the oxidation potential (0.6 V at pH 11, 0.75 V at pH 7 and 1.1 V at pH 3). However, both anodic and cathodic emissions were inhibited significantly by the addition of alkene (cyclopent-2-ene-1-acetic acid) solutions downstream of the working electrode. Further, the spectra at both anodic and cathodic sides shifted to the longer wavelength (>424 nm) compared to the original spectrum of Fe(III)TMPyP (422 nm), which was not observed with the addition of alkene solution. Therefore, the results suggest that the electrochemically generated oxo-ferryl species have been engaged in catalytic oxidation of alkene before the flow reaches the observation cell.

Alkenes↗
PubMed1990

Studies on the nephrotoxicity of aminoglycoside antibiotics and protection from these effects (9): Protective effect of inositol hexasulfate against tobramycin-induced nephrotoxicity.

We examined the protective effect of inositol hexasulfate (IS6) against tobramycin (TOB)-induced nephrotoxicity. In the electrophoretic analysis, TOB alone and IS6 alone were observed as single spots on the cathode and anode sides, respectively. However, in the mixture of TOB and IS6 preincubated at 37 degrees C for 3 hr, the tailing of the spots of TOB and IS6 were observed from the origin to the cathode and the anode sides, respectively, and the overlapping of the spots of TOB and IS6 was recognized at the origin. These results indicated that TOB directly interacted with IS6 in vitro. Assay of TOB binding to rat kidney brush border membranes (BBMs) indicated that IS6 inhibited the binding of TOB to BBMs through an interaction of TOB and IS6. No significant reduction in intrarenal TOB level was observed in the rats given TOB (90 mg/kg, s.c.) and IS6 (153 or 610 mg/kg, s.c.). However, the treatment of rats with a combination of TOB and IS6 reduced the degree of necrosis of renal tubular cells and also suppressed the increases in urinary protein, urinary enzyme activities, blood urea nitrogen and plasma creatinine induced by TOB. Additionally, we detected a complex of TOB and IS6 in the urine of rats given both compounds simultaneously. These results indicate that IS6 protects against TOB-induced nephrotoxicity and that the protective action of IS6 may be due to the inhibition of TOB binding to BBMs through an interaction of TOB with IS6.

Animals↗
PubMed1979

A calibration system for X-ray generators and tube factors.

An apparatus (Machlett's Dynalyzer II system) is described that makes real-time dynamic tests on the output and performance of the X-ray tube and generator so that a single exposure gives information on mA and mAs; exposure time (ms); kVp anode to earth; kVp cathode to earth; kVp cathode to anode; tube filament current; line voltage and radiation output of the tube (mR). The method of use is described together with the results of comparisons made with other test equipment. Some novel design features are of particular interest. The results show that by using this apparatus present design characteristics of X-ray generator-control-tube systems are such that the accuracy of calibration can be improved by at least an order of magnitude.

Calibration↗
PubMed1990

A study on the effect of electrical stimulation on living tissue: potential before, during and after galvanization with constant current of 20 microA through platinum electrodes.

Two platinum needles (therapeutic electrode) were inserted into the rabbit's auricle, and with the medial angle of the eye as the datum point of measurement, the electric potential was measured before, during, and after the galvanization with micro-current (20 microA). With the insertion of the needles alone, the potential between the needles and the datum point showed -0.10 to +0.28 V, which gradually decreased thereafter to reach stable levels ranging from -0.02 to +0.17 V in 3 or 4 days. When galvanized, the potential stood +0.75 to +1.30 V between the anode and the datum point, and -0.37 to -0.50 V between the cathode and the datum point. Then, 3 days later, the voltage rose +1.40 to +1.65V between the anode and the datum point, and went down -0.60 to -0.85 V between the cathode and the datum point. When the micro-current was switched off, the potential immediately decreased, and slight potential endured after 24 hrs. These findings revealed that the insertion of needles generated electric potentials, that galvanization charged the tissue, and that cessation of stimulation led to storage and discharge of electricity.

Animals↗
PubMed2002

Modeling the bidirectional reflectance of emissive displays.

The reflection properties of a display device influence the available contrast and affect the perception of subtle detail. The display reflection characteristics of flat-panel displays (FPDs) are appropriately described by a six-dimensional bidirectional reflectance distribution function (BRDF). I describe a Monte Carlo method for modeling the bidirectional reflectance of multilayer emissive structures used in electronic display devices. I estimate the complete BRDF using a one-dimensional angular distribution function of the luminance. I apply the method to model typical high-performance cathode-ray tube and FPD structures. I find that, for the BRDF signatures of cathode-ray tubes characterized by a specular and a quasi-Lambertian components, the estimated values for the specular and diffuse reflection coefficients agree well with low-resolution experimental measurements conducted with a rotation arm and a collimated probe. I show that emissive FPDs with thin-film organic layers on reflective substrates can exhibit a predominant specular peak broadened by short-range light scattering.

Data Display↗
PubMed2006

Spectral response variation of a negative-electron-affinity photocathode in the preparation process.

In order to research the spectral response variation of a negative electron affinity (NEA) photocathode in the preparation process, we have done two experiments on a transmission-type GaAs photocathode. First, an automatic spectral response recording system is described, which is used to take spectral response curves during the activation procedure of the photocathode. By this system, the spectral response curves of a GaAs:Cs-O photocathode measured in situ are presented. Then, after the cathode is sealed with a microchannel plate and a fluorescence screen into the image tube, we measure the spectral response of the tube by another measurement instrument. By way of comparing and analyzing these curves, we can find the typical variation in spectral-responses. The reasons for the variation are discussed. Based on these curves, spectral matching factors of a GaAs cathode for green vegetation and rough concrete are calculated. The visual ranges of night-vision goggles under specific circumstances are estimated. The results show that the spectral response of the NEA photocathode degraded in the sealing process, especially at long wavelengths. The variation has also influenced the whole performance of the intensifier tube.

Journal Article↗
PubMed1978

A novel rapid scanning microspectrophotometer and its use in measuring rhodopsin photoproduct pathways and kinetics in frog retinas.

A novel rapid scanning microspectrophotometer is described which utilizes a cathode ray tube as a measuring light source. Spectral scanning is accomplished electronically with a sampling time of 600 mus for each waveband. The cathode ray tube emission is chopped electronically into two separate beams, 180 degrees out of phase, resulting in a dual-beam configuration. A lock-in amplifier functions as a coherent detector to recover separately the signals from the two beams. The instrument generates separate voltage outputs, one proportional to the transmittance of a single sample and the other to the difference between two samples. A computer calculates both absorption and difference spectra directly from voltage measurements. A demonstration of the instrument's use to study kinetics of visual pigment photoproducts is presented. Two models of photoproduct sequence and kinetics were examined to determine which better represents the experimental data. The experiments show that environmental factors, such as pH, metabolic and respiratory state, interact in complex ways to determine the pathways and kinetics of photoproducts of rhodopsin in intact vertebrate eyes.

Animals↗
PubMed2003

Static and dynamic profile of the electric field within the bulk of fused silica glass during and after thermal poling.

We use the electric-field-induced second-harmonic (EFISH) technique to characterize, for the first time to our knowledge, the profile of the electric field induced within the bulk of fused silica glass samples both during and after thermal-poling treatment. During thermal poling, the initially homogeneous electric field decays exponentially from the anodic to the cathodic surface. After the poling treatment, a permanent electric field is induced within the bulk of the sample. It also decays exponentially from a positive value on the anodic surface to a negative value on the cathodic surface. The exponential decay constant depends on the thickness of the sample, the poling time, and the temperature. The temperature evolution of this constant makes it possible to retrieve the activation energy of the rapidly moving ionic species. This ensemble of observations indicates that modifications to models previously proposed are necessary.

Journal Article↗
PubMed2005

Enhancement of electroluminescence through a two-dimensional corrugated metal film by grating-induced surface-plasmon cross coupling.

We report enhancement of electroluminescence through opaque-topped metal cathodes in organic light-emitting devices (OLEDs), which are periodically corrugated in two dimensions. The enhancement is caused by grating-induced cross coupling and outcoupling of surface plasmons. The emission intensity observed at normal direction is enhanced by a factor of 4 compared with that of OLEDs with one-dimensionally corrugated metal cathodes and is higher than that observed from the transparent substrate side in uncorrugated OLEDs. We attribute the enhancement to the fact that the surface plasmons propagating in all lateral directions are coupled out into free space by the two-dimensional corrugated structure of the OLEDs. In addition, the emission from the transparent substrate side is also much enhanced owing to the efficient coupling out of the waveguide modes trapped in the emissive layer.

Journal Article↗
PubMed1985

Transcutaneous oxygen and carbon dioxide monitoring in sick neonates using a combined sensor.

Using a combined O2-CO2 sensor, we evaluated the effect of cathode size and membrane thickness and incorporation of correction factor upon transcutaneous O2-CO2 readings. The present studies were carried out in three phases in newborns less than a week of age. The data from these studies indicate that a combined O2-CO2 sensor with a smaller cathode, Teflon membrane and with a built-in correction factor can accurately reflect arterial O2 and CO2 tension and can replace the present two heated sensors.

Carbon Dioxide↗
PubMedDate not supplied

Study on photoconductivity of dye-polymer-based solid-state thin film.

In this article, we describe a solid-state photoelectrochemical cell for light detection. Safranine-T dye mixed with polyvinyl alcohol (PVA) solution was deposited on a conducting and transparent indium-tin-oxide (ITO)-coated glass that was used as one electrode and another ITO-coated glass as the counterelectrode. A solid polymeric electrolyte consisting of polyethylene oxide-ammonium perchlorate-ethylene carbonate and propylene carbonate with suitable weight ratio was prepared and sandwiched between these two ITO-coated glass electrodes, which were separated by a Teflon spacer about 50 microm thick. The cell was biased with a direct current source to make the dye and PVA-coated ITO as the anode and the other ITO as the cathode. On illumination by a tungsten lamp, from the cathode side, the change of photocurrent was measured. The dark current-voltage characteristics and the growth and decay of the photocurrent for steady and pulsed illumination were studied.

Biotechnology↗
PubMed1980

The microheterogeneity of human plasma alpha1-acid glycoprotein.

alpha1-Acid glycoprotein was isolated in the homogeneous state from the plasma of 33 normal individuals and subjected to analytical isoelectric focusing before and after treatment with neuraminidase. The native glycoprotein preparations, resolved into 6 to 8 bands, were quantitated and grouped into two classes according to the patterns obtained: One class exhibited a relatively anodic and the other a relatively cathodic distribution of the protein bands. The isoelectric points of these bands ranged from pH 2.90 to 3.30. After treatment with neuraminidase the resulting asialo-glycoproteins were also quantitated and afforded two types of fundamentally different patterns from those mentioned above, namely one type with one and the other type with two main bands and both exhibiting several minor components. The isoelectric points of the main bands were found to be of pH 4.55 and 4.70 while those of the minor bands were at both the anodic and cathodic side of the major bands. No apparent relationship between the patterns of the native and those of the asialo-glycoproteins could be established. In addition, a new variant was noted whose major band focused at a pH of 5.0. The microheterogeneity of alpha1-acid glycoprotein is thus interpreted to be due to the amino acid replacements of this protein in combination with the linkages of the sialyl to the galactosyl residues in the native protein.

Humans↗
PubMed1987

Modification of the isoinhibitors of human serum alpha 1-proteinase inhibitor (alpha 1-antitrypsin) by pancreatic proteases.

Due to the action of a serum protease, the two most cathodal isoinhibitors of the alpha 1-proteinase inhibitor (alpha 1-PI) are cleaved at the Gly5-Asp6 bond and lack two negative charges. In spite of this, these can bind trypsin and chymotrypsin, showing that the N-terminal pentapeptide is not indispensable for inhibition function. Pancreatic proteases also cleave a bond near the N-terminus in alpha 1-PI, resulting in a loss of two negative charges and a corresponding cathodal shift in the electrofocusing behavior of the isoinhibitors. Trypsin cleaves isoinhibitors near the N-terminus at a large inhibitor excess and unless an additional cleavage takes place, at least two of the new isoinhibitors remain active. An additional cleavage(s), most likely at a distance of 30-40 residues from the C-terminus results in a corresponding decrease of the molecular mass and a loss of inhibition function. Although the C-terminal cleavage peptide does separate from the protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, it remains associated with it under conditions of polyacrylamide gel isoelectric focusing. Chymotrypsin also cleaved alpha 1-PI near the N-terminus but this could be observed only at protease excess and the modified isoinhibitors did not form complexes with chymotrypsin. The molecular polymorphism of alpha 1-PI is partly explained by the absence of the N-terminal pentapeptide from some of the isoinhibitors.

Amino Acid Sequence↗
PubMed1986

The isoelectric focusing of creatine kinase variants: I. The heterogeneity of creatine kinase in human heart cytosol and mitochondria.

Creatine kinase isoenzymes in cytosolic and mitochondrial fractions from human cardiac tissues were studied by analytical and preparative isoelectric focusing (IEF), electrophoresis and immunoinhibition. Analytical IEF on agarose gels revealed many creatine kinase variants in human cardiac cytosol prepared by extraction with a hypotonic medium. The bands located at approximately pH 5.5 were shown to contain creatine kinase-MB and minute creatine kinase-BB bands by electrophoresis. Two bands which focused closely together in IEF (pH 6.85-7.0) showed an electrophoretic migration pattern similar to creatine kinase-MM. One of them (IP 6.85) showed a complete inhibition by anti-creatine kinase-M antibodies, whereas the other showed only 50% inhibition. Increasing the salt concentration of tris-HCl (0.1 mol/l) in the extraction medium resulted in additional creatine kinase variants. They were characterized by high alkaline isoelectric points and were not inhibited by anti-creatine kinase-M antibodies. These variants corresponded to two cathodic bands in electrophoresis. The treatment of washed mitochondria with phosphate buffer resulted in a release of mitochondrial variants with different isoelectric points, as shown by analytical IEF in agarose gels. The same pattern was obtained by using preparative IEF. Variants with high alkaline isoelectric points gave rise to two cathodic bands upon electrophoresis. These two bands resembled those present in cytosol after extraction with high salt concentration. No complete inhibition with anti-creatine kinase-M was observed in any of the eluates. The mitochondrial variants exhibited different affinities towards creatine phosphate and ADP. Variants with higher alkaline isoelectric points showed lower Km-values for these substrates than those with less alkaline isoelectric points.

Creatine Kinase↗