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PubMed1990

Novel apoprotein A-I-containing lipoprotein produced by a human hepatoma-derived cell line HuH-7.

The apoprotein A-I (apo A-I)-containing lipoprotein (LPHuH-7apoA-I) was isolated from the concentrated conditioned medium of human hepatoma-derived cell line HuH-7 by immunoaffinity chromatography. LpHuH-7apoA-I consists of two kinds of lipoproteins. One is a lipoprotein of large particle size (LpL) with broad electrophoretic mobility on agarose gel ranging from the origin to the position of prebeta-lipoprotein. LpL is protein-rich in composition (protein, 75.4% by weight) and is heterogeneous in size (34-17 nm in diameter) electron microscopically. However, the most intriguing properties of LpL are its partial electrophoretic mobility towards the cathode on agar gel. The other lipoprotein is of small particle size (LpS). It demonstrates prebeta-electrophoretic mobility on agarose gel. LpS is also protein-rich in composition (protein, 95.4% by weight) and is heterogeneous in size (16.5-8.4 nm in diameter) electron microscopically. LpL is obviously different from LP-X and LP-Y in property, although LP-X, LP-Y and a part of LpL migrate towards the cathode on agar gel electrophoresis. LpS is also different from human apo A-I-containing lipoprotein without apo A-II in property, although these two lipoproteins possess the same mobility on agarose gel electrophoresis. These results indicate that both LpL and LpS are novel lipoproteins which have not yet been reported. The major isoproteins of the apo A-I of LpHuH-7apoA-I are apo A-I isoprotein 2 (apo A-I2), apo A-I isoprotein 4 (apo A-I4) and apo A-I isoprotein 5 (apo A-I5), and are different from those of apo A-I in human plasma and in the conditioned medium of hepatoma-derived cell line HepG2. This result suggests the presence of a proteinase which converts proapoprotein A-I (apo A-I2) to apoprotein A-I (apo A-I4) in the conditioned medium of HuH-7.

Apolipoprotein A-I↗
PubMed1980

Effect of diet composition on the protein synthetic pattern of the rat pancreas after a feeding period of five days.

Rats were fed for five days on a protein-rich and on a carbohydrate-rich diet, respectively. One half of the pancreas of these rats was incubated with [3H]leucine and the other half with [14C]leucine and extracts from these pancreas halves were prepared. Mixtures of the differently labeled extracts were subjected to electrophoresis towards the anode as well as towards the cathode on a polyacrylamide gel containing urea at pH 8.5. Several secretory enzymes could be identified on the gels. Along the gels the 3H : 14C ratio was determined in 1 mm slices. The results show that after five days of feeding a diet there is some adaptation to diet composition. Generally rather small changes in synthetic rate occur. Only one component, the cathodic chymotrypsinogen shows an important difference in synthetic rate under the two circumstances.

Adaptation, Physiological↗
PubMed1975

Purification of the phytohemagglutinin family of proteins from red kidney beans (Phaseolus vulgaris) by affinity chromatography.

Half-gram quantities of phytohemagglutinin lectins are purified from saline extracts of red kidney beans (Phaseolus vulgaris) by affinity absorption on porcine thyroglobulin-Sepharose. All of the mitogenic and erythroagglutinin activity of the saline extract is removed by this absorbent, and 74% of the original erythroagglutinating activity elutes from the affinity absorbent representing a 25-fold purification. Five distinct proteins appear in the polyacrylamide gel electrophoresis of the affinity absorbent eluate. Although all five proteins specifically bind to porcine thyroglobulin, the cathodal migrating proteins bind more strongly than the anodal migrating proteins. The most cathodal proteins are potent erythroagglutinins. This simple, efficient method is used to prepare all the active components of the phytohemagglutinin family in large yield and high purity.

Chromatography, Affinity↗
PubMed1985

Proteolytic cleavages in alpha 1-antitrypsin and microheterogeneity.

Antitrypsin was resolved into two pools by ion-exchange chromatography. Pool 2 contained three anodal isoinhibitors and an N-terminal sequence identical with the one found by others. Pool 1 contained, in addition to the anodal ones two cathodal isoinhibitors as well. The sequencing data of Pool 1 indicate that the cathodal proteins are formed from the anodals by a cleavage of the Gly5-Asp6 bond in the molecule.

Amino Acid Sequence↗
PubMed1982

Electroshock afterdischarges are related to neuronal oscillability: neuronal models of Aplysia.

Identifiable giant neurons of Aplysia explored intracellularly behave differently at the offset of an intracellular electroshock (IES) or after a synaptic 'tetanization', according to their functional type: neurons of the stable type depolarize and fire at the offset of the IES, anodal or cathodal, thus eliciting an afterdischarge (AD). The threshold of this AD is lowered if the neuron is destabilized, i.e. converted from the stable to an oscillatory type (for instance by decalcification). Neurons normally of the tonic type are more sensitive to an IES, eliciting a longer afterdischarge than the stable neurons. Extracellular electroshock (EES) anodal or cathodal, applied directly on desheathed somata of Helix give long-lasting afterdischarges at the offset. In addition, EES stimulating presynaptic terminals or axons leads to a high frequency synaptic input on remote neurons. At the offset of this input either prolonged synaptic afterdischarges or postsynaptic rebounds of the membrane potential sustaining bursts of decreasing amplitude denote apparent oscillatory properties of the synaptically activated neuron. Finally, any conversion by convulsants of tonic neurons to oscillators highly facilitates the elicitation of afterdischarges of axons simultaneous to paroxysmal depolarization shifts of the homologous somata. These results indicate that afterdischarge elicitation is highly facilitated (low threshold) in normal oscillatory neurons and/or chemically destabilized neurons.

Animals↗
PubMed1977

Studies on the pre-alpha-lipoprotein in patients with familial lecithin: cholesterol acyltransferase deficiency.

The present study shows that regular alpha1- and pre-alpha-lipoproteins cannot be detected in serum of patients with familial lecithin: cholesterol acyltransferase (LCAT) deficiency. After electrophoresis on agarose gel only one single band of albumin mobility was observed in the alpha1-pre-alpha-region. In contrast to sera of normal subjects neither the anodic front nor the cathodic part of this region revealed any lipoprotein bands in the patients studied. The lack of the cathodic part might be related to a low amount of alpha1-lipoprotein. The apparent lack of the anodic front could be related to a low amount of "albumin-Apo-A-I-containing lipoprotein" (AAL). AAL was not detected with conventional methods in LCAT deficient sera. The alpha1-lipoprotein was made up of two immunologically identical peaks, both of which had a Sudanophilic character. After incubation of lysolecithin with albumin and AAL and subsequent thin layer chromatography, a significant lysolecithin-binding capacity of AAL was demonstrated, superior to that possessed by albumin.

Acyltransferases↗
PubMed1985

Nervous propagation along 'central' motor pathways in intact man: characteristics of motor responses to 'bifocal' and 'unifocal' spine and scalp non-invasive stimulation.

In 23 healthy adult volunteers motor action potentials (MAPs) were elicited in upper and lower limb muscles during stimulation of appropriate sites at spinal and scalp level, through skin electrodes. 'Bifocal' stimulation of scalp and spine motor tracts was performed with 2 plaques (3.5 cm2 each), delivering single pulses of 440-940 mA, less than 50 microseconds in duration, which elicited high voltage (up to 10 mV) MAPs in arm and leg muscles. 'Unifocal' stimulation of scalp was carried out through a cathode consisting in a belt or in a series of rectangular interconnected plaques secured around the head, 1-2 cm rostral to the nasion-inion plane, and in a circular anode placed on the appropriate scalp site. MAPs with similar amplitude-latency characteristics were recorded with both 'bifocal' and 'unifocal' stimulating methods. However, the 'unifocal' stimulation necessitated 5-10 times less current than the 'bifocal' one. The 'unifocal' device using the interconnected plaques (6-12 in number) provided the most tolerable stimuli with the lowest amount of current (60-106 mA, rectangular pulses of 100-150 microseconds). Conduction times and velocities of motor pathways in various 'central' and 'peripheral' districts were calculated. Voluntary contraction of target muscles remarkably enhanced MAP amplitudes during scalp, but not during spine stimulation. A nerve action potential was recorded from ulnar nerve during scalp stimulation. MAPs in hand muscles to scalp stimulation were obliterated by the simultaneous activation of the peripheral fibres innervating the target muscle, because of collision between ortho- and antidromically propagated motor impulses. Anodal stimuli showed liminal values significantly lower than the cathodal ones. Mapping studies have been carried out with 'unifocal' scalp stimulation by using different types of anode and of stimulus parameters.

Action Potentials↗
PubMed1987

Postsynaptic potentials in motoneurons caused by spinal cord stimulation in humans.

Epidural spinal cord stimulation (SCS) causes facilitation and/or inhibition of spinal motoneurons many segments below the level of the cathode. On the assumption that a spinal cord pathway is activated by the cathode the conduction velocity of the fiber system responsible for the facilitation of soleus motoneurons was estimated to be between 21.5 and 27 m/sec. It is clear that SCS in man can generate postsynaptic potentials in spinal neurons and thus is capable of modifying transmission in spinal segmental pathways.

Adult↗
PubMed1988

An analysis of peripheral motor nerve stimulation in humans using the magnetic coil.

We compared conventional electrical and magnetic coil (MC) stimulation of distal median nerve in 10 normal subjects and 1 patient. Orthogonal (90 degrees to volar forearm)-longitudinal (the plane of the MC aligned with the long axis of nerve or wire), tilted (to 45 degrees) longitudinal, and tangential edge orientations elicited maximal or near maximal compound motor axon potentials (CMAPs) without simultaneous co-activation of ulnar nerve. Transverse and symmetrical tangential orientations were inefficient. A simulation study of an ideal volume conductor confirmed these findings by predicting that the maximum current density was near the outer edge of the MC and not at the center where the magnetic flux intensity is maximal. An orthogonal-longitudinal MC induces a current in the adjacent volume conductor (for example elbow or wrist), which flows in the same circular direction as in the MC. This differs from a tangentially orientated MC which classically elicits current flow in the volume conductor opposite in circular direction to that in the MC. Amplitude and latency of the CMAP were both altered, but not identically, by changing the intensity of MC and cathodal stimuli. Rotating an orthogonal-longitudinal MC through 180 degrees, thus reversing the direction of current flow, elicited single fiber muscle action potentials whose peak latencies differed at most by 100 microseconds. Thus, the (virtual) cathode and anode are significantly closer (i.e., 5-6 mm) with MC than with electrical stimulation where they are at least 20 mm apart. A disadvantage of MC stimulation is the imprecision in defining exactly where the distally propagating nerve impulse originates. In different subjects, using maximum output and orthogonal or tilted (to 45 degrees) longitudinal orientations, the calculated site of excitation in the median nerve varied 2-15 mm distal to the midpoint of the contacting edge of the MC. This limits the usefulness of the MC in its current configuration for determining distal motor latencies. Future advances in MC design may overcome these difficulties.

Action Potentials↗
PubMed1984

Response of C3H/10T1/2 fibroblasts to an external steady electric field stimulation. Reorientation, shape change, ConA receptor and intramembranous particle distribution and cytoskeleton reorganization.

C3H/10T1/2 mouse embryo fibroblasts were stimulated by a steady electric field ranging up to 15 V/cm. The percentage of spindle-shaped cells increased with the field strength and duration of the stimulation. These cells oriented preferentially with their long axis perpendicular to the field direction. A small percentage of the cells were found to move slightly toward the cathode during the course of electric stimulation. Although no apparent field-induced redistribution of fluorescent-labelled concanavalin A (conA) receptor along the cell periphery was observed, the bright perinuclear area appeared preferentially on the anode side. Correlative fluorescence and scanning electron microscopy (SEM) revealed no difference in the density of conA-gold microsphere labels on either side of the cell. The density of intramembranous particles on the E-face of the plasma membrane was 54% higher on the anode side than on the cathode side of the cell. The microfilament bundles were observed to be disrupted after 30 min of 10 V/cm stimulation by rhodamine phalloidin labelling of F-actin. The cell sensitivity to electric field-induced reorientation and cell shape changes was reduced by pretreatment with conA, and to a lesser extent, with succinyl conA or wheat germ agglutinin (WGA). ConA pretreatment alone also reduced the prominence of microfilament bundles. However, post-field lectin binding to the cell has no effect on cell recovery. It is possible that the generally flat 10T1/2 cells retract and realign in order to minimize the disruption of their membrane potential. The conA binding-mediated receptor-cytoskeletal linkage temporarily immobilizes the cell and inhibits subsequent field-induced shape changes.

Actins↗
PubMed1989

Developmental expression of creatine kinase isozymes in mammalian lens.

Four different isoforms are thought to comprise the creatine kinase of enzymes which regulate energy metabolism through the interconversion of ADP and creatine phosphate. In addition to these well characterized isoforms, MM, MB, BB and mitochondrial creatine kinase, several uncharacterized variants with atypical electrophoretic mobility have been described. In mammalian lens, creatine kinase isoforms exhibit both a regional and developmental pattern of expression. In neonatal rat and human lens, the only isoform expressed is a variant cathodic creatine kinase. Near the time of sexual maturation (11-13 yr) there is a dramatic increase in the expression of BB creatine kinase in human lens. In rat lens, a similar pattern of isoenzyme expression is also seen near the time of sexual maturation (5-6 weeks). In the mature rat lens, in addition to the cathodic variant, there is expression of BB and, to a lesser extent, MM creatine kinase. Using a polyclonal antisera, we have localized BB creatine kinase to the cuboidal epithelial cells of the adult rat lens. This unique pattern of isoenzyme expression and developmental regulation suggests a more complex scheme for the regulation of creatine kinase gene expression than previously postulated.

Adolescent↗
PubMed1983

Schistosoma japonicum: immunological characterization and detection of circulating polysaccharide antigens from adult worms.

The antigenic constituents of a trichloroacetic acid (TCA)-soluble fraction of adult Schistosoma japonicum were studied with immunoelectrophoresis, and compared with those of Schistosoma mansoni. Eight TCA-soluble antigens of S. japonicum were demonstrated, five of which showed immunological identity with S. mansoni antigens. Of the eight antigens, five antigens with anodic motility were found as circulating antigens in S. japonicum-infected hamster and rabbit sera; the major circulating antigen was the circulating anodic antigen (CAA). Two other antigens, with cathodic motility, including the circulating cathodic antigen (CCA), were demonstrable as circulating antigens in S. mansoni infections, but not in S. japonicum infections. Most of the circulating antigens were shown to be gut-associated. Only one antigen, line 2, which was not demonstrable as circulating antigen and which was present in the parenchyma of the worms, was found to be specific for S. japonicum. Using an ELISA for the detection of CAA in the sera of S. japonicum-infected rabbits, a lower detection level of 100 ng CAA/ml serum was achieved. Moreover, at 7-8 weeks after infection, a direct relationship between worm burden and CAA level was demonstrated.

Animals↗
PubMed1993

Electrochemical detection of dipeptides with selectivity against amino acids.

Electrolysis of a basic mobile phase containing biuret reagent [Cu(II) and a tartrate salt] at high (> 1.2 V vs. Ag/AgCl) potentials modifies the glassy carbon electrode. This modified anode oxidizes dipeptides, yielding signals expected for a one-electron transfer, even at low (down to 0.7 V vs. Ag/AgCl) potentials and in the absence of intentionally added copper(II) ion in the reagent or mobile phase. The same modification demonstrates a selectivity to alpha-dipeptides over amino acids that is unprecedented. The product of the anodic reaction is reduced at a downstream cathode at low positive potentials. Sensitivities for several amino acids and dipeptides are reported under several conditions. Neither the anodic nor the cathodic signals for the buiret complex of the tripeptide Ala-Ala-Ala are significantly altered because of the modification.

Amino Acid Sequence↗
PubMed1996

Hydrolytically stable amino-silica glass coating material for manipulation of the electroosmotic flow in capillary electrophoresis.

A hydrolytically stable amino-silica glass coating material was fabricated inside fused-silica capillaries, using sol-gel technology. Aminopropyltriethoxysilane was used as the precursor in the glass formation process. The net charge at the surface of the coating material depends on the degree of protonation of the amino groups and the degree of ionization of the silanol groups, thus enabling manipulation of the magnitude and direction of the electroosmotic flow (EOF). At low pH (< 6.0), the coating bears a net positive charge, which results in an electroosmotic flow from the cathode toward the anode and minimizes the wall-solute interactions of basic species. At high pH (> 6.5), the coating surface bears a net negative charge and the coated capillary behaves like an uncoated one, having an EOF in the cathodic direction. The amino-silica glass coating has also been shown to be extremely stable under both acidic and basic conditions. The reproducibility of the electroosmotic mobility of five different capillaries was found to be 7% R.S.D. The utility of the material is shown with the separation of basic proteins, peptides and basic compounds.

Acids↗
PubMed1983

Supernumerary lactate dehydrogenase isozymes in human gliomas.

Supernumerary bands in agarose gel electrophoresis of lactate dehydrogenase (LDH) were frequently observed in extracts of human gliomas. The supernumerary fractions which migrated cathodic to LDH-2 and/or cathodic to LDH-3 were designated LDH-2' and LDH-3'. These extra bands were clearly seen in certain gliomas and less distinctly in others, being more frequent in primitive or undifferentiated tumours. The extra bands seen in gliomas differ from the LDH-X of the testis, but LDH-2' seemed correspond to LDH-Z in placenta, hydatidiform mole, and choriocarcinoma. These sub-bands are interpreted as being produced by gliomas and as oncofetal enzymes.

Astrocytoma↗
PubMed1985

Electrolytic current parameters in the dorsolateral tegmental obesity syndrome in rats.

Female rats received lesions in the dorsolateral tegmentum formed by the 20 sec passage of 0.25, 0.5, or 0.75 mA anodal or 0.5, 0.75, 1.0, 1.25, or 1.5 mA cathodal current. Although all lesion parameters induced roughly comparable body weight gains, the largest effect was seen with 1.25 mA cathodal current. Anodal lesions were much larger and induced transient periods of hyperactivity that confounded the effects of the lesions on body weight gain.

Animals↗
PubMed1978

Permeability and diffusion coefficient of oxygen in membranes for oxygen electrodes.

Oxygen diffusion coefficient and permeability in thin membranes of low-density polythene and laminated polytetrafluorethylene (PTFE) are measured over the temperature range of about 20 to 30 degrees C. The diffusion coefficient is estimated from the time response of a large area platinum electrode covered with the membrane material and exposed to a sudden change in PO2. outside the membrane. The electrode is operated at a very low polarising voltage so that consumption of oxygen at the cathode surface is made negligible. This method is considered to be more reliable than that based on operating the electrode at more normal polarising voltages at which the boundary condition for oxygen tension at the cathode surface is often ill-defined. Oxygen permeability is estimated from the flux of oxygen across an area of membrane separating a nitrogen gas stream from one containing oxygen, the oxygen being measured with a platinum/zirconium oxide reversible cell. Diffusion coefficient in the membranes is very temperature dependent, whereas oxygen solubility is only weakly so. The diffusion coefficient at 25 degrees C is 0.28 +/- 0.06 . 10(-6) and 1.0 +/- 0.2 . 10(-6) cm2 . sec-1 for PTFE and polythene respectively. The corresponding values for permeability are 0.80 +/- 0.08 . 10(-7) and 0.43 +/- 0.04 . 10(-7) ml O2 atm-1 . cm-1 . sec-1.

Diffusion↗
PubMed1985

Immunoglobulin G, A, and M--clonal restriction in multiple sclerosis cerebrospinal fluid and serum--analysis by two-dimensional electrophoresis.

Immunoglobulin G, A, and M (IgG, IgA, and IgM) were purified from multiple sclerosis (MS) cerebrospinal fluid (CSF) and sera and analyzed by two-dimensional electrophoresis. The light (L)-chains of MS CSF IgG were of limited diversity and dominated by about 30 major spots and many less intense spots. CSF IgG of patients with subacute sclerosing panencephalitis (SSPE) was dominated by 10 to 20 intense L-chain spots. L-chains from patients with fungal, syphilitic, and tuberculous infections of the central nervous system (CNS) ranged from 70 to in excess of 300 spots. The patterns of L-chains in MS CSF and autologous sera were different, indicating amplified synthesis of particular L-chains in MS CNS. Cathodic IgG fractions differing in isoelectric point by 0.1 to 0.3 pH units were isolated. SSPE CSF IgG fractions were dominated by a few L-chain spots, MS CSF fractions contained less than 20 spots, and MS serum fractions contained about 200 spots. MS CSF mu-chains were similar in isoelectric point range to serum but fractionated into discrete spots compared with a diffuse pattern in serum. MS CSF IgA alpha-chain spot overlapped in mobility with serum alpha-chains except a portion of the alpha-chain complex in CSF was shifted cathodically forming discrete spots. The CSF L-chains of both IgM and IgA were completely dissimilar to serum. These studies indicate major limited diversity and compartmentalized CNS synthesis of IgG, IgA, and IgM in MS. The restricted clonal pattern is proposed as consequent to B-cell stimulation by disease-related antigen(s) with limited epitope complexity. The dominance of a small number of L-chains supports results from idiotypic analysis suggesting finite clonal complexity of MS CSF IgG and indicates the feasibility of structural analysis of MS CSF L-chains, particularly amino acid sequence determinations.

Humans↗