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Biomedical subjects

Y Kudo

Publications and source records attributed to Y Kudo.

At least 289 records · Page 16Linked to original sources
PubMed1988

Measurement of intracellular Ca2+ in the bullfrog sympathetic ganglion cells using fura-2 fluorescence.

The intracellular free Ca2+ concentration ([Ca2+]i) of the bullfrog sympathetic ganglion cell was measured with fura-2 fluorescence under various conditions, and compared with changes in membrane potential recorded with an intracellular electrode. The [Ca2+]i was 109 nM on average under the resting condition and increased by raising the extracellular K+, stimulating repetitively the pre- or post-ganglionic nerve, or by applying acetylcholine or muscarine. Since all these procedures depolarized the cell membrane, most of the rise in [Ca2+]i could be the result of opening of voltage-dependent Ca2+ channels. However, Ca2+ entries through nicotinic acetylcholine receptor channels and the channel activated by the muscarinic acetylcholine receptor were also indicated by considering the threshold for the opening of voltage-dependent Ca2+ channels (for both entries) or a limited number of the cells showing the latter response.

Acetylcholine↗
PubMed1988

Neuronal death in vitro: parallelism between survivability of hippocampal neurones and sustained elevation of cytosolic Ca2+ after exposure to glutamate receptor agonist.

Hippocampal neurones isolated from rat embryos were maintained on glial monolayers in a medium containing no L-glutamate (Glu). The administration of Glu for a limited period induced a massive death (loss) of neurones. The degree of neuronal loss increased with time after exposure to Glu. The extent of neuronal loss assessed 24 h after exposure to Glu was dependent upon the concentration Glu and on the duration of the exposure. An increase in concentration of external Ca2+ during the exposure to Glu enhanced the extent of loss. By contrast, an increment in concentration of environmental Mg2+ reduced the loss. The inhibitor of spike firing, tetrodotoxin (TTX) and the suppressor of Ca2+ entry, nitrendipine, both decreased the extent of loss, when delivered prior to Glu. The toxicity of Glu became progressively more apparent with further days of culture. The cytosolic concentration of Ca2+ ([Ca2+]i) in single hippocampal neurones was monitored by microscopic fluorometry under conditions equivalent to those in the death assay. The time required for the recovery of [Ca2+]i from the level elevated by exposure to Glu to pre-stimulus levels closely paralleled the degree of neuronal loss; i.e. high doses of Glu, long periods of exposure, high concentrations of external Ca2+, low concentrations of external Mg2+, and extended days of culture all retarded [Ca2+]i recovery, while TTX and nitrendipine accelerated it. These findings show that neuronal death resulting from an extraneous excitation (excitotoxicity) can be analyzed in vitro. Furthermore, substantial support has been provided to the hypothesis that excitotoxicity has an underlying mechanism, an excess loading of Ca2+ in neuronal cytoplasm.

Animals↗
PubMed1988

Identification of two taurine receptor subtypes on the primary afferent terminal of frog spinal cord.

1. Effects of taurine on primary afferent terminals in the frog spinal cord were examined by a sucrose-gap method applied to a dorsal root (9th or 10th segment). 2. In a normal Ringer solution, taurine (1 mM, applied for 5s at a rate of 0.04 ml s-1, 0.2 mumol) caused a hyperpolarization, but a higher concentration (10 mM, applied at the same rate, 2.0 mumol) caused a biphasic response consisting of a hyperpolarization followed by a slow onset depolarization. A similar biphasic response could also be observed in tetrodotoxin-treated preparations. 3. When the concentration of extracellular Mg2+ was increased up to 9.0 mM, the depolarizing response to taurine was augmented. The rate of the augmentation was dependent upon the extracellular Mg2+ concentration. 4. The depolarizing effect was selectively antagonized by bicuculline in concentrations (10-30 microM) that had no significant antagonizing action on gamma-aminobutyric acid (GABA)-induced depolarization. On the other hand the hyperpolarizing effect of taurine was selectively reduced by strychnine (0.1 microM) which had no antagonizing effect on responses to glycine. 5. These results suggest that in the frog spinal cord there are at least two subtypes of taurine receptor whose pharmacological profiles resemble GABA and glycine receptors in the mammalian central nervous system, and whose sensitivity may be modulated by extracellular Mg2+.

Action Potentials↗
PubMed1988

Positive reaction in mouse ligated intestinal loop assay with nonenterotoxigenic and nonhemolytic strains of Staphylococcus aureus.

Nonenterotoxigenic and nonhemolytic strains of Staphylococcus aureus exhibited a positive reaction in the mouse intestinal loop assay except for a strain negative for the egg yolk reaction. Edema and swelling in all positive loops, increased bacterial cell numbers within intestinal loops, and extremely close adhesion to or inclusion of numerous bacterial cells in HeLa cells after inoculation of the strains were observed. These results suggest a possible invasive ability of the strains.

Animals↗
PubMed1988

Recurrence of subacute thyroiditis over 10 years after the first attack in three cases.

We saw a total of 4 episodes of the recurrence of subacute thyroiditis in 3 patients out of 222. The recurrent episodes were similar to the first episodes of subacute thyroiditis. The titers of various viral antibodies were not increased significantly during the clinical course of the recurrence. Regarding the HLA typing, A26, B35 and C3 were positive in all 3 patients. The association between the occurrence of subacute thyroiditis and the presence of HLA-B35 and C3 has hitherto been reported, although the association of HLA-A26 with recurrent type of subacute thyroiditis was observed and described for the first time in this report. It is suggested that HLA-A26 may somehow be related to the predisposition to the recurrence of subacute thyroiditis which developed after more than 10 years.

Adult↗
PubMed1988

Nerve excitability test using fine needle electrodes.

The NET using needle electrodes is a simple and useful test. Children readily tolerate the procedure. For prognosticative purposes it is more effective than the conventional NET using surface electrodes. When positive responses to NET using needle electrodes are recorded after 3 days from onset of palsy, irrespective of the absolute threshold value, prognosis is good. In Bell's palsy, NET is positive for 90%, and for 73% in Hunt's syndrome. Apart from one case our patients showed complete recovery by EMG evaluation.

Acupuncture Therapy↗
PubMed1988

Vitamin K effect in low birth weight infants.

Factor II coagulant antigen (FII-AG), the protein induced by vitamin K absence or antagonist II (PIVKA-II), and coagulant activity (normotest) were measured in low birth weight infants. The factor II coagulant antigen and normotest levels in one-day-old babies were lower than those of full-term infants (P less than .005, P less than .01, respectively). Infants whose normotest levels were less than 30% at one day (group A) received vitamin K2, and the others whose normotest levels were greater than 30% at one day (group B) were not treated. At this time, the mean factor II coagulant antigen level was significantly lower in group A than in group B (P less than .05). During the first seven days of life, in 65.2% of the infants in group B the PIVKA-II level became positive, but this did not occur in any infant in group A. After vitamin K treatment, there was greater improvement in the normotest level in infants with positive PIVKA-II levels than in those with negative PIVKA-II levels. This observation indicates that the hypoprothrombinemia found in low birth weight infants at one day of age is attributable to reduced synthesis of factor II coagulant antigen in the liver at this stage, but the prophylactic administration of vitamin K seemed to be effective even in such infants, probably because of the increase in factor II coagulant antigen synthesis (P less than .001) during the first seven days of life.

Antigens↗
PubMed1988

Evidence for modulation by ATP of amino acid transport in human placenta.

The effect of ATP on placental amino acid transport was studied by measuring the uptake of alpha-(methylamino)-isobutyrate in brush border microvillous plasma membrane vesicles prepared from human full-term placental syncytiotrophoblasts which were incubated with or without ATP. The presence of a Na+ gradient from the outside to the inside of the vesicles prepared after incubation with ATP resulted in a higher initial rate and an increased transport of alpha-(methylamino)-isobutyrate, while Na+ gradient-independent alpha-(methylamino)-isobutyrate uptake was not different in either type of membrane vesicle. The increase in transport activity was not inhibited by cycloheximide. Kinetic analysis showed that ATP enhanced transport activity by increasing the maximal velocity (Vmax) of transport, without significant changes in the affinity (Km) of the carrier for the substrate, suggesting an increase in carrier number in placental syncytiotrophoblasts incubated with ATP.

Adenosine Diphosphate↗
PubMed1988

Treatment of hydropic patients by immunoglobulin with methyl B12.

Recently several investigations have been reported suggesting that the cause of endolymphatic hydrops might be an immunologic disorder of the endolymphatic space, including the endolymphatic sac. As the first choice in a conservative treatment by medication, the authors have used a combination of prednisolone and furosemide per os, which is rather safe and effective for hydrops patients in a subacute stage. However, some patients do not respond to this treatment or gradually become immune to this medication. With these patients, we have tried an intravenous administration of immunoglobulin G with methyl B12, expecting a curative effect on immunologic deficiency in the endolymphatic space. Compared with a group of patients without this treatment, the group receiving it showed rather good scores in hearing improvement; however, vertigo and tinnitus remained almost unchanged.

Adult↗
PubMed1987

Characterization of amino acid transport systems in human placental brush-border membrane vesicles.

Brush-border microvillous plasma membrane vesicles were prepared from human full-term placental syncytiotrophoblasts and purified 33-fold from the homogenate with reference to a membrane marker enzyme, alkaline phosphatase (EC 3.1.3.1). Transport of alpha-(methylamino)isobutyrate by the membrane vesicles was stimulated in the presence of an Na+ gradient from the outside to the inside of the vesicles. The initial rate of uptake in a 10-s period was enhanced with increasing concentration of Na+ in the external medium. The level of alpha-(methylamino)isobutyrate transported into the vesicles reached a maximum 1 min after the start of incubation at 37 degrees C, and then decreased with time due to efflux. Extrapolation to infinite medium osmolarity showed no uptake, indicating transport of alpha-(methylamino)isobutyrate into membrane vesicles. The initial rate of uptake was dependent on temperature and pH: the highest rate occurred at 37 degrees C and the optimal pH was 8.0. When the alpha-(methylamino)isobutyrate concentration was varied, the initial rate of uptake dependent on an Na+ gradient (out greater than in) obeyed Michaelis-Menten kinetics with Km and Vmax values of 1.07 mM and 3.23 nmol/10 s per mg of protein, respectively. Cross-inhibition patterns indicated that at least three Na+-dependent and two Na+-independent carrier-mediated pathways existed in the human placental brush border. One Na+-dependent pathway interacted with all substrates tested. Another Na+-dependent route interacted with L-proline, alpha-(methylamino)isobutyrate, and L-methionine, while a third pathway was selective for L-methionine. One Na+-independent pathway was selective for L-cysteine, while the other pathway interacted with all substrates tested.

Amino Acids↗
PubMed1987

Optical monitoring of excitatory synaptic activity between cultured hippocampal neurons by a multi-site Ca2+ fluorometry.

The fluorescence intensities from cultured hippocampal neurons loaded with a Ca2+-indicator (fura-2), showed spontaneous, periodical oscillations, which were synchronized among the cells. Tetrodotoxin or 2-aminophosphonovalerate, a glutamate-receptor antagonist, blocked the oscillation. The rising phase of the fluorescence was accompanied by a burst of inward currents, as monitored by a patch electrode. It is thus suggested that the fluorescence elevation represents an increase in intracellular Ca2+ concentration accompanied by excitation of neurons which formed synaptic connections between each other. This method for detection of neuronal activity including synaptic excitation escapes from the limitations of the conventional technique employing microelectrodes.

2-Amino-5-phosphonovalerate↗
PubMed1987

Cytoplasmic calcium elevation in hippocampal granule cell induced by perforant path stimulation and L-glutamate application.

Calcium-dependent fluorescence of a Ca2+ indicator (fura-2) loaded in the slice of guinea pig hippocampus was measured by a microscope/video-camera/photometry system. Tetanic stimulation of the perforant path (PP) or application of L-glutamate caused increment of the fluorescence from the dendritic and somatic layers of the granule cells in the dentate gyrus. Magnitude of the increment depended on the frequency and intensity of the PP-stimulation or on the dose of L-glutamate. 2-Aminophosphonovaleric acid, a glutamate-receptor antagonist, suppressed both PP-stimulus-induced and L-glutamate-evoked responses, while tetrodotoxin blocked the former only. Thus the fluorescence increment should represent an elevation of Ca2+ concentration in the postsynaptic cytoplasm of the granule cells.

2-Amino-5-phosphonovalerate↗
PubMed1987

Isolation and characterization of monoclonal antibodies against pili of Corynebacterium renale and Corynebacterium pilosum.

Five monoclonal antibodies against pili of Corynebacterium renale 115 P+ (piliated clone) and two monoclonal antibodies against pili of C. pilosum 92 P+ (piliated clone) were produced. These antibodies bound to pili of the homologous strain in in enzyme-linked immunosorbent assay (ELISA) and agglutinated P+ but not P- (non-piliated clone) of each homologous strain. The five monoclonal antibodies against C. renale 115 P+ pili were divided into 2 groups, comprising 16/5, 160/1 and 32/6 and 13/4 and B20/3, based on the results of a competitive binding assay. The results may indicate the presence of at least 2 distinct antigenic areas on the pilus of C. renale 115 P+. The monoclonal antibodies of the first group inhibited adhesion of C. renale 115 P+ bacteria to the epithelial cells of bovine vulva, while the second group did not. Two monoclonal antibodies against C. pilosum 92 P+ pili recognized the same area on the pilus of C. pilosum 92 P+, and inhibited the adhesion of C. pilosum 92 P+ bacteria to the epithelial cells of bovine vulva. The adhesion of these bacteria was inhibited by the monoclonal antibodies in the form of IgG as well as by the Fab fragment. The strains of C. renale and C. pilosum which reacted with each of the anti-C. renale 115 P+ pili and anti-C. pilosum 92 P+ pili monoclonal antibodies were small in number and of restricted distribution.

Agglutination Tests↗