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PubMed1996

Malic dehydrogenase isoenzymatic pattern in lung-nematode parasite species.

The malic dehydrogenase (MDH) isoenzymatic pattern of Dictyocaulus viviparus, Protostrongylus rufescens, and Slovakian and Spanish isolates of D. filaria was studied. The MDH isoenzymatic pattern in both isolates of D. filaria was characterized by the presence of three phenotypes: (1) a single, slow anodic band; (2) a single, fast anodic band; and (3) a large spot matching its migration with bands 1 and 2. These three phenotypes may be explained as the existence of only one gene locus for the MDH in D. filaria. Allelic frequencies and the Hardy-Weinberg test were determined for Slovakian and Spanish isolates of D. filaria. This test indicated that the population was not in Hardy-Weinberg equilibrium. The MDH isoenzymatic pattern of D. viviparus displayed the same phenotypes 1 and 2 observed in D. filaria. Furthermore, the MDH isoenzymatic pattern of P. rufescens was characterized by the presence of two bands with anodic and cathodic migration. The isoenzyme with anodic migration appeared more intensively stained than did that with cathodic migration. This last isoenzyme was not observed when the samples had been stored for 1 month.

Alleles↗
PubMed1998

Morphologic, biometric, and isoenzyme characterization of Trichuris suis.

Trichuris suis isolates were collected from the cecum of Sus scrofa domestica (pig) and S. s. scrofa (wild boar). Morphology and biometry studies were carried out. Morphology studies showed the existence of typical caudal papillae in males of T. suis from wild boars, but no other difference was observed in the biometric parameters (total length, esophageal length, posterior-portion body length, and spicular length) of T. suis isolated from either host. Individual extracts were subjected to malate dehydrogenase (MDH), malic enzyme (ME), glucose 6-phosphate dehydrogenase (G6PD), lactate dehydrogenase (LDH), and superoxide dismutase (SOD) isoenzyme analysis following starch-gel electrophoresis, and the isoenzyme patterns were compared with those obtained from other species of trichurids. MDH, ME, G6PD, LDH, and SOD isoenzyme patterns were identical for T. suis from both hosts. MDH isoenzyme patterns were characterized by the presence of one cathodic isoenzyme. ME, G6PD, and LDH isoenzyme patterns indicated the presence of three phenotypes, whereas the SOD isoenzyme pattern showed only one phenotype characterized by the existence of two (anodic and cathodic) bands. Different LDH and SOD isoenzyme patterns observed for T. suis, T. ovis, and T. skrjabini confirm once more that isoenzyme patterns have potential as a diagnostic tool for differentiation of different species of Trichuris.

Animals↗
PubMed2004

Characterizing the "gold standard" image for laparoscopic surgery.

BACKGROUND: The term "gold standard" is often used to describe preferred display devices, frequently without substantiating evidence. A meaningful and objective measure of display quality for endoscopic surgery is required. METHODS: Typical colors from five tissue types were arranged in a striped pattern and displayed on four devices: a medical-grade cathode ray tube monitor, a liquid crystal display, a digital light projection display, and an obsolete cathode ray tube (CRT) monitor. The breadth and color contrast of the stripes were adjusted until the patterns became indiscernible to 12 subjects. The data provide a discernibility threshold. RESULTS: The liquid crystal display (LCD) monitor provided the best image. The medical grade and obsolete CRTs were second and third, respectively, and the projection display provided the most inferior image. CONCLUSIONS: A meaningful and relevant measurement of image display quality for laparoscopic surgery based on the discernibility threshold is provided. Of the devices tested, the LCD is the best in terms of image, although the CRT may be preferred at off-axis viewing angles. The projection system, however, offers compensatory ergonomic advantages.

Benchmarking↗
PubMed2005

The influence of iontophoresis on acyclovir transport and accumulation in rabbit ear skin.

PURPOSE: The aim of this work was to explore the effect of iontophoresis on acyclovir (ACV) accumulation and permeation. In particular, the objectives were to check the efficacy of the transport mechanisms, electromigration and electrosmosis, on drug accumulation. METHODS: Permeation experiments were performed in vitro, using rabbit ear skin as barrier, from donor solutions at pH 3.0, 5.8, and 7.4. At the end of the experiments, drug accumulation in epidermis and dermis was measured. Anodal and cathodal iontophoresis were applied at pH 3.0, whereas only anodal iontophoresis was used at pH 5.8 (current densities 0.06--0.50 mA/cm(2)) and 7.4. RESULTS: Cathodal iontophoresis was more efficient than anodal iontophoresis on ACV permeation across the skin at pH 3.0. At pH 5.8, ACV flux and accumulation increased with current density during anodal iontophoresis. At pH 7.4, anodal iontophoresis produced a remarkable increase of flux and a modest increase of accumulation. Overall, anodal flux increased as the pH of the donor solution was increased as a result of the increase of the skin net negative charge. CONCLUSIONS: From the results obtained in the present work, it can be concluded that iontophoresis application increases ACV flux and, to a limited extent, accumulation in the skin.

Acyclovir↗
PubMed1985

Improved internal defibrillation with twin pulse sequential energy delivery to different lead orientations in pigs.

Internal cardiac defibrillation with an intravascular catheter was compared with a new method for internal cardiac defibrillation using 2 pulses delivered in sequence directly to the myocardium. For the sequential pulses, the first pulse was passed through an intravascular catheter (Medtronic 6880), between the anode in the superior vena cava-atrial junction region and the cathode in the apex of the right ventricle. The second pulse was delivered between the catheter tip in the right ventricular apex as cathode and an oval plaque electrode (Medtronic TX-7) secured on the epicardium of the left ventricular free wall as anode. Defibrillation pulses were of truncated, trapezoidal waveform (65% tilt), separated by 1, 10 and 100 ms. Using the catheter alone, 36 normal pig hearts could be defibrillated by 44 J. However, 22 pig hearts (60%) could not be defibrillated with energies below 35 J. Defibrillation threshold was improved with sequential twin pulses, the improvement being dependent on pulse separation (42, 34 and 19 J, at 100-, 10- and 1-ms separation, respectively; F = 14.6, df = 2.29, p less than 0.01). In conclusion, sequential twin pulse defibrillation provides a considerable reduction in energy necessary for defibrillation in comparison to single pulses using the catheter alone. In this study, the optimal separation was 1 ms.

Animals↗
PubMed1986

Optimal mode of transesophageal atrial pacing.

The optimal mode of transesophageal atrial pacing was determined by clinical electrophysiologic studies in 15 healthy adult volunteers. The point at which the unipolar atrial electrogram was biphasic and largest in amplitude (35.4 +/- 1.6 cm from the incisors) was considered the best stimulation site for atrial pacing. The stimulation threshold on bipolar pacing (using the proximal pole as cathode and the distal pole as anode) at this site was 27 +/- 7 mA, which was significantly lower (p less than 0.001, n = 10) than that on unipolar cathodal stimulation (41 +/- 8 mA). Although the stimulation threshold tended to be higher with a No. 10Fr electrode catheter (30 +/- 5 mA) than with a No. 6Fr catheter (27 +/- 7 mA), the difference was statistically insignificant (n = 9). When the interpolar distance in bipolar stimulation was varied in 5 steps from 12 to 80 mm, the threshold was lowest at the distance of 24 mm. Of the 10 pulse durations tested, ranging from 0.25 to 128 ms, 8 ms appeared most desirable in minimizing the total amount of current and chest discomfort accompanying the pacing. With the optimal site, interpolar distance and pulse duration, transesophageal atrial pacing was successfully performed in all patients, without producing significant complications such as chest pain. Transesophageal atrial pacing is noninvasive, technically simple and efficient, and may be valuable in the diagnosis and treatment of various cardiac arrhythmias.

Adult↗
PubMed1986

Contribution of the anode to ventricular excitation during bipolar programmed electrical stimulation.

Anodal excitation may contribute to the initiation of ventricular arrhythmias during bipolar pacing in the canine ventricle. To determine if anodal excitation occurs during bipolar programmed ventricular stimulation in humans, ventricular electrograms adjacent to the anode and cathode were recorded using a specially designed hexapolar electrode catheter in 10 patients. Single extrastimuli were delivered during ventricular pacing at stimulus strengths slightly above the late diastolic threshold and at 2 to 5 times late diastolic threshold. Evidence of anodal excitation was observed in 18 of the 52 combinations (35%) of stimulus strengths and electrode configurations tested, and occurred in 9 of the 10 patients; it consisted of earliest ventricular activation adjacent to the anode (8 patients) or simultaneous activation at the anode and cathode (3 patients). This occurred either with premature stimuli (3 patients) or during the basic drive and extrastimuli (6 patients). Comparison of local activation times during unipolar pacing supported an anodal contribution to excitation during bipolar pacing and suggested that inhomogenous conduction delays were not responsible for these findings. Thus, anodal excitation occurs frequently during bipolar programmed stimulation and produces marked changes in local myocardial activation, which may potentially influence the initiation of ventricular arrhythmias.

Adult↗
PubMed1994

Effects of voltage and respiration on impedance in nonthoracotomy defibrillation pathways.

The effects of applied voltage and phase of respiration on impedance of pathways used by implantable cardioverter-defibrillators were investigated. Patients were studied at implantation of cardioverter-defibrillators using epicardial (n = 12) or transvenous and subcutaneous (SQ) (n = 30) electrodes. Transvenous-SQ pathways were right ventricular cathode to SQ anode and coronary sinus cathode to SQ anode. Transvenous-transvenous pathways were right ventricle to coronary sinus and right ventricle to superior vena cava. Patients with nonthoracotomy electrode systems were studied at end-expiration and end-inspiration. Five shocks of 65 to 745 V (0.2 to 34 J) were given in random order in sinus rhythm. Over this range, end-expiratory impedance decreased monotonically for all pathways. This effect was greatest for transvenous-SQ pathways (13 +/- 3% to 17 +/- 4%, p < 0.001), intermediate for transvenous-transvenous pathways (5 +/- 4% to 8 +/- 5%, p < 0.001), and least for epicardial pathways (3 +/- 3%, p = 0.006). Paired data in inspiration and expiration showed that inspiration increased impedance in transvenous-SQ pathways (p < 0.001) but not in transvenous-transvenous pathways. Further, the effects of respiration and voltage on impedance in transvenous-SQ pathways were interactive (p < 0.001): Inspiration increased voltage-dependence of impedance. The magnitude of the inverse relationship between voltage and impedance depends on type of defibrillation pathway. The effect of respiration on impedance suggests that voltage-dependence of impedance is greatest in the lungs. These findings have potential relevance for intraoperative testing of cardioverter-defibrillators and selection of pathways for low-energy cardioversion.

Aged↗
PubMed1980

Electric currents, bone remodeling, and orthodontic tooth movement. I. The effect of electric currents on periodontal cyclic nucleotides.

Osteogenesis has been found to occur in response to the application of electric currents to bone. The objective of this experiment was to study the effects of D.C. electric currents on periodontal tissues in cats. Cyclic nucleotides, compounds known to be involved in cellular activation, were studied by immunohistochemistry in the involved tissues. Three groups of three young adult cats each were treated for 1, 3, and 7 days, respectively, by a device delivering 15 microamperes of direct current to bone osteoblasts and PDL cells stained intensely for cAMP and cGMP were observed adjacent to the cathode and anode, and bone apposition was found near the cathode. These results suggest that electric stimulation enhances cellular enzymatic phosphorylation activities in periodontal tissues and may be a potent tool in accelerating alveolar bone turnover.

Alveolar Process↗
PubMed1984

Counterflow immunoisotachophoresis on cellulose acetate membranes.

Discontinuous electrophoresis on cellulose acetate membranes with the use of 0.06 M Tris-HCl (pH 6.7) as the leading electrolyte and 0.012 M Tris-beta-alanine (pH 8.6) as the terminating one results in concentration of the proteins present in the system on the Cl-/beta-alanine- boundary. If the antigen solution is placed in a "pocket" ahead of the moving boundary, a counterflow to the cathode arises due to electroendosmosis. At constant voltage the migration rate of the boundary drops and that of electroendosmosis does not change until they become equal. In such a stationary position, the antigen-containing solution is passing through the Cl-/beta-alanine- boundary to the cathode, while all the proteins are completely "absorbed" on the boundary as highly concentrated bands. Addition of ampholytes to the antigen solution contributes to the isotachophoretic separation of a protein mixture on the strip. The concentrated and separated antigens can be revealed by immunofixation, immunodiffusion, or crossed immunoelectrophoresis in gel. The technique is approximately 100 times more sensitive compared to the usual immunodiffusion and immunoelectrophoresis methods on cellulose acetate membranes, and is applicable to the detection of trace amounts of antigens in the urine, liquor, amniotic fluid, tears, and other biological fluids with low protein contents.

Animals↗
PubMed1985

Double-beam flying spot scanner for two-dimensional polyacrylamide gel electrophoresis.

The construction of a double-beam photometer in which the light source is a cathode ray oscilloscope is described. The light spot from the oscilloscope was focused and reduced in size at the gel plane to give a diameter of less than 0.15 mm and make it possible to scan over a 50 X 59-mm rectangle; using reduced spatial resolution (spot less than 0.2 mm) the area scanned becomes 70 X 90 mm. The light from the CRT was divided into two beams; one was directed through the transparent object to a photomultiplier and the other to a reference photomultiplier. The signals from these two detectors were converted to the logarithm of the ratio by a logging amplifier to give a direct measure of absorbance. Positioning of the spot, control of light intensity, and measurement of absorbance were carried out through an interface to a 16-bit computer. The relationship between measured and actual absorbance was linear over the range of absorbance 0 to 2, which could be raised to 1 to 3 by placing a neutral filter in the reference beam. The system generated an image containing 256 X 256 pixels in about 5 min, the scanning speed was determined by the persistence time of the P4 phosphor on the cathode ray tube, and faster scans can be made using A6 phosphor.

Calibration↗
PubMed1985

Rapid electrotransfer of proteins from polyacrylamide gel to nitrocellulose membrane using surface-conductive glass as anode.

A new type of inexpensive horizontal apparatus for the electrophoretic transfer of proteins from a gel to an immobilization membrane has been developed. In this system, gel and membrane were directly pressed between two flat electrodes. A surface-conductive glass was used as anode and a stainless-steel plate as cathode. Proteins could be transferred from polyacrylamide gel to nitrocellulose sheet, with a yield of at least 90% in 60-90 min, without overheating, using a voltage gradient of 30-40 V/cm. Moderate volumes of separate anodic (with 20% methanol) and cathodic (with 0.1% sodium dodecyl sulfate) buffers were suited for optimal transfer of proteins with relative molecular mass (Mr) in the 14,000-94,000 range.

Animals↗
PubMed1985

Identification of human alcohol dehydrogenase isozymes by disc polyacrylamide gel electrophoresis in 7 M urea.

Polyacrylamide gel electrophoresis in the presence of 7 M urea provides a simple, reproducible method for the identification of cathodic alcohol dehydrogenase (ADH) isozymes. Treatment of native ADH dimers with 7 M urea and 1 mM dithiothreitol results in a complete dissociation of the 40,000 Mr subunits. Electrophoresis of urea-dissociated ADH isozymes yields a single protein band for homodimers and two bands of equal intensity for heterodimers. The ADH subunits pi, alpha, gamma 2, gamma 1, and beta exhibit electrophoretic mobilities of 0.71, 0.79, 0.88, 0.95, and 1.0, respectively. Thus, the identity of any cathodic ADH isozyme can be determined from the electrophoretic mobilities of its component subunits.

Alcohol Dehydrogenase↗
PubMed1986

Two-dimensional electrophoretic characterization of microheterogeneous myelin basic protein fragments.

A new two-dimensional polyacrylamide gel electrophoresis (PAGE) system with minislab gel apparatus was devised for the rapid (4 h) analysis of peptide fragments derived from the enzymic digestion of myelin basic protein (MBP). The first dimension consisted of 5% polyacrylamide running gels in 1.9 M potassium glycinate, pH 7.3, with 4.3% stacking gels in 0.08 M potassium glycinate, pH 10.3. Anodic and cathodic buffer chambers contained 38 mM glycine/5 mM Tris, pH 8.3, and 10 mM Tris-HCl, pH 8.1, respectively. This system fractionated MBP peptides on the basis of charge. By contrast, acid-urea 15% PAGE separated MBP peptides by both charge and size. A two-dimensional system of 5% PAGE followed by sodium dodecylsulfate 15% PAGE (Laemmli) was used to resolve MBP fragments from pepsin and cathepsin D digests; this analysis indicated that cathodic mobilities could be predicted by the ratio of basic to acidic amino acids in each peptide. This method should be particularly powerful in combination with immunoblotting to identify microheterogenous fragments arising from normal and pathological metabolism of MBP.

Electrophoresis, Polyacrylamide Gel↗
PubMed1983

Separation and partial characterization of multiple forms of rat liver alcohol dehydrogenase.

Rat liver alcohol dehydrogenase was purified and four isoenzyme forms, demonstrated by starch gel electrophoresis, were separated by O-(carboxymethyl)-cellulose chromatography. Each of the isoenzymes had a distinct isoelectric point. All isoenzymes were active with both ethanol (or acetaldehyde) and steroid substrates, and had similar Michaelis-Menten constants for each of the substrates and coenzymes studied. The three isoenzymes with the lowest migration toward the cathode exhibited the same pH optimum of 10.7 for ethanol oxidation, a greater activity with 5 beta-androstan-3 beta-ol-17-one than with ethanol as a substrate, and an unchanged electrophoretic mobility following storage in the presence of 100 microM dithiothreitol. By contrast the isoenzyme with the highest mobility toward the cathode exhibited a pH optimum of 9.5 for ethanol oxidation, a low steroid/ethanol ratio of activity, and converted to the migrating pattern of the two isoenzymes with intermediate mobility when stored. The similarities between the isoenzymes of rat liver alcohol dehydrogenase differ considerably from differences in substrate specificity exhibited by isoenzymes of horse liver alcohol dehydrogenase.

Alcohol Dehydrogenase↗
PubMed1976

Electrochemical characterization of immobilized NAD+.

Nicotinamide adenine dinucleotide (NAD+) has been covalently attached to alginic acid using carbodiimide coupling, thereby producing a macromolecular adduct of NAD, which can be rendered either soluble or insoluble by adjustment of pH. It was found that this NAD+-alginic acid complex was enzymatically active, and also that the oxidized form could be electrochemically reduced without loss in enzymatic activity. This NAD+ adduct has now also been polarographically characterized as to its two-step reduction waves, which are slightly shifted toward more cathodic potential as compared to free NAD+. When controlled electrolysis was conducted to reduce the bound NAD+ at the cathode, the NADH so formed by electrochemical action was found to be again oxidizable either enzymatically or electrochemically without loss in co-enzymatic function. The NADH adduct produced by electrochemical reduction of the NAD+ adduct has also been characterized by voltammetry.

Alginates↗
PubMed1987

Only one of the two interconvertible forms of mitochondrial creatine kinase binds to heart mitoplasts.

When analyzed by cellulose acetate electrophoresis, solubilized pig or rabbit heart mitochondrial creatine kinase is shown to exist under two distinct forms. The less cathodic one (form 1) is a dimer and the other having a higher cathodic mobility (form 2) has a molecular weight of about 350,000. The latter form can be converted into the former by incubation at alkaline pH or when the enzyme forms a reactive or an abortive complex with its substrates. This conversion is a reversible phenomenon and is not due to proteolysis. When rabbit heart mitoplasts are treated with the creatine kinase releasing agents, the enzyme is always solubilized as its form 2 and conversion to form 1, when it occurs, always take place after solubilization. Form 2 is also the only form which can be bound to pig or rabbit mitoplasts. Thus form 2 may be the actual form associated with heart mitochondria in vivo.

Animals↗
PubMed1983

Studies on sphingomyelinase and beta-glucosidase activities in Niemann-Pick disease variants. Phosphodiesterase activities measured with natural and artificial substrates.

Cultured fibroblasts were studied from 12 cases of Niemann-Pick disease group C. In 11, sphingomyelinase and glucocerebrosidase (and beta-glucosidase) activities were reduced to around 50% of those of controls. On isoelectric focusing, all 12 strains lacked sphingomyelinase activity in the major cathodic region (pI 8.0). The defect was also demonstrated with the artificial phosphodiester substrates bis(4-methylumbelliferyl) phosphate and 4-methylumbelliferyl pyrophosphate diester. In control fibroblasts and those heterozygous for types A or B or group C Niemann-Pick disease, the major sphingomyelinase peak electrofocused at pI 8.0. No direct interaction could be demonstrated by mixing experiments between group C Niemann-Pick extracts and those of type A disease or Gaucher disease. Profiles for beta-glucosidase activity appeared normal in Niemann-Pick group C fibroblasts. No reduction of sphingomyelinase or glucocerebrosidase activities was found in Niemann-Pick group C liver, nor any attenuation of cathodic sphingomyelinase activity in the affected tissue. Results suggest that sphingomyelinase expression differs in fibroblasts and liver. Enzyme defects associated with Niemann-Pick disease group C were only observed in cultured cells.

Fibroblasts↗