[Changes in colloid osmotic pressure in double filtration plasmapheresis].
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Adult↗
Biomedical subjects
A Hirota
Publications and source records attributed to A Hirota.
Mapping of early development of electrical activity in the embryonic chick heart using multiple-site optical recording.
1. Using a multiple-site optical recording method with a 100-element photodiode array and a voltage-sensitive merocyanine-rhodanine dye, we have been able to monitor, for the first time, spontaneous electrical activity in pre-fused cardiac primordia in the 6- and 7-somite chick embryos. 2. To study the regional development of spontaneous electrical activity in the early embryonic pre-contractile chick heart at the later 7-9-somite stages, we have also recorded optically action potentials simultaneously from the entire heart, and constructed maps of the early development of electrical activity. 3. The data show that during the 6-9-somite stages, the size of the active area gradually increases, and that the development of electrical activity was spatially non-uniform: two peaks of activity were found in the right and left sides of the cono-ventricular region at the 7-8-somite stages. As development proceeded to the 9-somite stage, several peak areas of activity appeared. 4. The results are discussed in relation to the spatial pattern of proliferation of electrically active cells in the early phases of cardiogenesis.
Action Potentials↗
Natural case of Aujeszky's disease in the dog in Japan.
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Animals↗
Conduction pattern of excitation in the amphibian atrium assessed by multiple-site optical recording of action potentials.
Spontaneous action potentials were monitored from multiple sites in the bullfrog atrium using a voltage-sensitive merocyanine-rhodanine dye together with a 100-element photodiode matrix array, and we have assessed the spread of the excitation from the pacemaker. Isochrone curves of conduction were obtained by timing the initiation of the action potential-related optical signals: we constructed maps of the spread. Excitatory waves appeared to conduct radially from the pacemaking area over the atrium, and the conduction velocity in the left atrium exceeded that in the right atrium.
Animals↗
Terrecyclic acid A, a new antibiotic from Aspergillus terreus. IV. Absolute stereochemistry of terrecyclic acid A.
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Aspergillus↗
Reciprocal biological activities of the cyclic tetrapeptides chlamydocin and HC-toxin.
Chlamydocin, a potent cytostatic agent against cultured mammalian cells, and HC-toxin, a host-specific phytotoxin, are cyclic tetrapeptides containing the same epoxide alpha-amino acid. We show here that these compounds have reciprocal biological activity; HC-toxin is cytostatic against cultured mastocytoma cells, and chlamydocin has host-specific toxin activity against maize. Chlamydocin and another related cyclic peptide, Cyl-2, are less host-specific than HC-toxin because maize tolerant to HC-toxin is more sensitive to chlamydocin and Cyl-2.
Animals↗
Development of electrical rhythmic activity in early embryonic cultured chick double-heart monitored optically with a voltage-sensitive dye.
Double-hearted embryos were produced by whole-embryo culture of chick embryos which were microsurgically cut through the tissue of the anterior intestinal portal at the 1- to 6-somite developmental stage, at the time when the cardiac primordia have not yet fused in the bulboventricular region. The cultured embryos were removed from an incubator usually at the 7- to 10-somite stages of development, and then spontaneous electrical action potentials and/or contractions were optically recorded simultaneously from both the right and left half-hearts, using a 10 X 10- element photodiode matrix array together with a voltage-sensitive merocyanine-rhodanine dye (NK 2761). At the 7- to 8-somite stages, spontaneous action potentials were detected from bilateral prebeating half-hearts or sometimes from one half-heart. In each half-heart, the first spontaneous beating was often observed in the half-heart of the 9 somite embryos. In the beating half-hearts regular activity was always observed, while in the prebeating half-hearts at the 7- to 8-somite stages, both the regular and irregular rhythms of action potentials were detected, and the incidence of occurrence of regular activity significantly outnumbered that of the irregular rhythm. The heart rate in the left half-heart was faster than that in the right half-heart in the great majority of the prebeating and beating double-hearted embryos.
Action Potentials↗
Optical recording of membrane potential responses from early embryonic chick ganglia using voltage-sensitive dyes.
Changes in absorbance of voltage-sensitive merocyanine-rhodanine dyes were used to monitor electrical responses in the semilunar ganglion of 4-10-day-old developing chick embryos. The electrical responses were simultaneously recorded from many positions in the ganglion. Stimulation of the afferent nerve fibers (the ophthalmic division of cranial nerve V) with a suction electrode led to changes in light absorption of the stained ganglia. With both the depolarizing and hyperpolarizing pulses, the change was largest at 700 nm and was eliminated at a wavelength of 620 nm where the voltage-dependent absorption change of the dyes disappears. In the 4-10-day-old embryonic ganglia, two types of optical membrane potential responses, 'non-conducted' and 'conducted' responses, were identified. The non-conducted response varied with the intensity of the stimulus and had the nature of an electrotonic spread. Furthermore, this non-conducted response exhibited an 'initial upstroke-response' followed by the steady-state plateau evoked by larger depolarizing pulses. The conducted responses were blocked by tetrodotoxin (TTX) or by high external potassium concentration. The incidence of the conducted responses increased as development proceeded from the 5th to the 10th day of age. Thus, the TTX-sensitive action potential activity is probably generated initially in the semilunar ganglion during the 5-10-day-stage of development. These data represent the first demonstration of membrane potential responses in early embryonic intact nervous system. Furthermore, these studies demonstrate the usefulness of voltage-sensitive dyes in the analysis of the organizing process of embryonic neuronal functions during these early stages of development.
Animals↗
Effects of calcium on electrical propagation in early embryonic precontractile heart as revealed by multiple-site optical recording of action potentials.
The effects of Ca2+ on electrical propagation in early embryonic precontractile chick hearts were studied optically using a voltage-sensitive merocyanine-rhodanine dye. Spontaneous optical signals, corresponding to action potentials, were recorded simultaneously from 25 separate regions of the eight-to-nine-somite embryonic primitive heart, using a square photodiode array. Electrical propagation was assessed by analyzing the timing of the signals obtained from different regions. Electrical propagation in the heart was suppressed by either lowering or raising extracellular Ca2+. Similar effects were produced by a Ca2+ ionophore (A23187). We have also found that electrical propagation across the primordial fusion line at the midline of the heart was enhanced by increasing, and depressed by lowering, external Ca2+. One possible interpretation is that intercellular communication in the embryonic precontractile heart is regulated by the level of the intracellular Ca2+ concentration, and it is suggested that intercellular communication across the primordial fusion line strongly depends on external Ca2+.
Action Potentials↗
Optical studies of excitation-contraction coupling in the early embryonic chick heart.
Excitation-contraction coupling at the onset of beating in the 9-10-somite embryonic chick heart was studied by means of an optical method together with a voltage-sensitive merocyanine-rhodanine dye. Spontaneous optical signals were recorded simultaneously from many areas of the embryonic heart, using a square photodiode matrix array. At time of initiation of the heartbeat, spontaneous optical signals consisting of two components were often detected. The first component (1st signal) is a dye-related absorption change due to the action potential, and the second component (2nd signal) is a light scattering change due to contraction. When Ca2+ in the bathing solution was partly replaced by Mg2+, the peak size of both signals was reduced. The correlation between the 1st and 2nd signals corresponded to the relationship between excitation and contraction. The formation of excitation-contraction coupling exhibited a regional non-uniformity in the developing 9-10-somite embryonic hearts: contraction was first generated in the right ventricular region, and then the contractile area spread widely over the whole of the heart. The curves of the excitation-related 1st signal vs. the contraction-related 2nd signal obtained from different areas were not superimposable. Decoupling of excitation from contraction was produced by raising the Ca2+ concentration in the bathing solution, by lowering the Na2+ concentration or by inclusion of a Ca2+ ionophore (A23187). Replacement of the bathing solution with D2O or hypertonic solution also suppressed excitation-contraction coupling. The results suggest that in the early embryonic initial beating chick heart, the contractile system is activated by Ca2+ influx across the sarcolemma accompanying the action potential, and that a Na+-Ca2+ exchange mechanism participates in the relaxation phase of the heartbeat.
Action Potentials↗
Early events in development of electrical activity and contraction in embryonic rat heart assessed by optical recording.
Spontaneous action potential and contraction in the early embryonic heart of the rat have been monitored optically using a voltage-sensitive merocyanine-rhodanine dye together with a multiple-element photodiode matrix array, and the onset of rhythmical action-potential activity in the early phases of rat cardiogenesis was conclusively determined for the first time. Spontaneous rhythmical action potentials were first generated in the central part of the embryonic heart at the middle period of the 3-somite stage of development, at 91/2 days after copulation. Subsequently, contractions coupled with the action potential also appeared at the end of the 3-somite stage. Usually, at the 3-somite stage, spontaneous action signals were synchronized among the different areas in the heart. From this result, it is evident that the paired right and left cardiac primordia are fused completely at the time of initiation of spontaneous electrical activity. In the 3-somite embryonic heart, excitatory waves were conducted radially over the heart, at a uniform rate (0.4-0.8 mm/s), from the pace-making area. However, the regional priority of pace-making activity is not rigid but is flexible.
Action Potentials↗
Structure of alahopcin (nourseimycin), a new dipeptide antibiotic.
The structure of alahopcin (nourseimycin) (1), a new dipeptide antibiotic isolated from Streptomyces, has been established to be (2S, 3R)-2-[(L-alanyl)amino]-4-formyl-3-(hydroxy-aminocarbonyl)butyric acid. 1 exists in two cyclic hemiacetal type tautomers formed by intramolecular ring closure between the hydroxyamino group and the formyl group in aqueous solution. The structure of the new weakly acidic amino acid (2), a constituent of 1, is revealed to be (2S, 3R)-2-amino-4-formyl-3-(hydroxyaminocarbonyl)butyric acid, and 2 also exists in two cyclic hemiacetal type tautomers in aqueous solution.
Anti-Bacterial Agents↗
[Clinical studies of ceftizoxime suppositories in the pediatric field].
Ceftizoxime suppository (CZX-S) was given to 19 children with infections, including upper and lower respiratory tract infections, urinary tract infections and otitis media at dose level of 18-83 mg/kg/day divided into 2-3 times. Clinical response was excellent in 12 patients, good in 6 patients and poor in 1 patient. Bacteriological response was eradicated in 11 strains, decreased in 3 strains and unchanged in 4 strains. No severe side effects were observed with this drug. These results obtained suggest that CZX-S should be a useful antibiotic in treatment of infections in pediatric field.
Bacteria↗
[Multiple-site optical recording of action potentials].
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Action Potentials↗
Effect of increased systemic venous pressure on thoracic duct and peripheral lymph flow in dogs.
In congestive heart failure, lymph flow from the cannulated thoracic duct is greatly increased. However, there has been scant data on lymph flow in the intact lymphatic system with systemic circulatory congestion. In the present study, thoracic duct and peripheral lymph flow were qualitatively determined using heated cross-thermocouples in seven mongrel dogs. Central venous pressure was raised artificially by infusing large volumes of crystalloid solution equivalent to a maximum of 30% of body weight. Although both thoracic duct and peripheral lymph flow increased with an intact (closed) lymphatic system, the increase was notably less than with a transected (opened) cervical thoracic duct. With systemic circulatory congestion, cannulated thoracic duct lymph flow circumvents a major lymph impediment to lymph flow (i.e. high central venous pressure) and therefore considerably overestimates in vivo central lymph flow in this condition.
Animals↗
Circus-movement tachycardia in frog atrium monitored by voltage-sensitive dyes.
Circus-movement tachycardia was studied using voltage-sensitive merocyanine-rhodanine dyes (dye XVII and NK2761). Excitatory waves were optically measured simultaneously from eight different regions of a ring of tissue formed from frog atrium. Application of acetylcholine in Ca2+-free solution (10(-10)-10(-9) g/ml) shortened the duration of optical action signals to cause nonuniform change in optical signal durations in about 60% of the preparations. Circus-movement tachycardia was produced by proper reduction and regional nonuniformity of optical signal durations. Under these circumstances it is easy to evoke circus-movement tachycardia by giving an extra stimulus to the site that shows a difference in optical signal durations.
Acetylcholine↗
Terrecyclic acid A, a new antibiotic from Aspergillus terreus. III. 13C NMR spectrum of terrecyclic acid A.
Assignment of the fifteen carbons of terrecyclic acid A, C15H20O3, a new sesquiterpene antibiotic, in the 13C NMR spectrum was performed by 13C-[1H] selective proton decoupling experiments, comparison with spectra of its derivatives and chemical shifts.
Antibiotics, Antineoplastic↗
Optical evidence for calcium-action potentials in early embryonic precontractile chick heart using a potential-sensitive dye.
Using an optical method for monitoring membrane potential, spontaneous action potentials in the 7- to 9-somite embryonic precontractile chick hearts were measured. The optical action potential in the 7- to 9-somite embryonic heart was lacking 'phase 0' and 'phase 1' attributable to the fast Na+ current. The embryonic precontractile heart continued to generate spontaneous action potentials in a Na+-free solution or in the presence of tetrodotoxin. Such an action potential was blocked by adding Co2+, Mn2+, Ni2+, La3+, D-600 or GEDTA, and the frequency, the amplitude, and the rate of rise of the spontaneous action potentials depended closely upon the external Ca2+ concentration; reducing the external Ca2+ concentration resulted in suppression of the spontaneous excitability. From the above results, we concluded that the spontaneous action potential in the early phases of cardiogenesis is characterized as a Ca2+-dependent action potential.
Action Potentials↗