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Biomedical subjects

Y Fukuda

Publications and source records attributed to Y Fukuda.

At least 973 records · Page 54Linked to original sources
PubMed1983

Neurotensin potentiates the potassium-induced release of endogenous dopamine from rat striatal slices.

The effects of neurotensin on the release of endogenous dopamine (DA) from rat striatal slices were investigated. DA was extracted by the aluminium adsorption method and assayed electrochemically by high-performance liquid chromatography. Neurotensin (2-100 microM) potentiated the potassium-induced release of striatal endogenous DA in a concentration-dependent manner. This neurotensin-induced release of DA was completely abolished in calcium-free medium containing EGTA 1 mM. The presence of tetrodotoxin 2 microM did not alter the effect of neurotensin 10 microM. On the other hand, neurotensin did not affect the uptake of [3H]DA into the striatal slices. In additional experiments, we confirmed that the KCl-induced release of DA in the nucleus accumbens was also potentiated b neurotensin. These results suggest that neurotensin has a direct effect on the central DA nerve terminals and releases DA in a Ca2+-dependent manner.

Animals↗
PubMed1983

The development of alveolar septa in fetal sheep lung. An ultrastructural and immunohistochemical study.

The morphogenesis of pulmonary alveolar septa in the sheep was studied by light microscopy, transmission electron microscopy and light microscopic immunohistochemistry for the detection of elastin. The primordia of alveolar septa developed in the glandular stage in areas subjacent to the epithelium, and formed alveolar septa by protruding into the glandular lumina. In their earliest stage, the primordia consisted of groups of fibroblasts, which were associated with elastic fibers and unit collagen fibrils and were surrounded by epithelial basement membrane and by more immature fibroblasts. The fibroblasts in the primordia subsequently became myofibroblasts or smooth muscle cells. In the alveolar zone of the glands, elastic fibers were exclusively found in the primordia of alveolar septa in early developing lung. In early developing lung, wavy, thickened epithelial basement membranes were found in the regions of the glands, which eventually underwent considerable expansion of their surface areas, especially in the primordia of alveolar septa and the bifurcations in the alveolar zones. Areas of fusion of the basement membranes of capillary endothelial cells and epithelial cells in the alveolar zone were found after the formation of the primordia of alveolar septa was accomplished. These areas of fusion were not found in the primordia themselves, but in regions between the primordia. Epithelial cell flattening and differentiation occurred after the formation of the primordia of alveolar septa, and flattening was first observed in the areas of the primordia and the bifurcations of the alveolar zones.

Animals↗
PubMed1983

Bilateral reorganization of the rat optic tract following enucleation of one eye at birth.

In albino rats with one eye removed at birth (NE rats), electron microscopic studies were made on the optic tract (OT) to count the fibers and to measure their thickness. In addition, experiments were made in NE rats to know the physiological properties of the optic pathway such as conduction velocity, synaptic delay and so on. The number of fibers in the OT of NE rats was compared with that constituting the crossed and uncrossed pathways of normal adult rats. In NE rats the fiber count increased by about 30,000 in the OT ipsilateral to the remaining eye while it decreased by about the same amount in the contralateral OT. The axonal cross section area of OT fibers was measured as an index for fiber thickness. No marked abnormalities were found in the OTs of NE rats with regard to the morphological dimension. Relay cells (P-cells) of the LGN were recorded by electrical stimulation of the optic pathway. The uncrossed projection of NE rats to the LGN was characterized by the following points: (1) P-cells responding to stimulation of the uncrossed fibers were encountered in NE rats much more frequently than in normal adult rats. (2) Synaptic delays assumed to be involved in trans-synaptic activation of P-cells by the uncrossed fibers were calculated at larger values than for P-cells activated by the crossed fibers in NE rats and normally grown rats.

Aging↗
PubMed1983

The ventilatory response to hypoxia in the anesthetized rat.

The hypoxic ventilatory response of the anesthetized rat was measured using a progressive hypoxia test whilst end-tidal Pco2 was maintained at a constant level. The ventilatory response to hypoxia was expressed by the equation, VE = Vo + A/(Pao2-C)(VE, total ventilation in l BTPS . min-1; Pao2, arterial Po2 in mm Hg). The hypoxic ventilatory drive, A, averaged 4.1 +/- 2.5 1 . min-1 . mm Hg (mean +/- SD), from which a value of 252 1 . min-1 . mm Hg was calculated on the basis of appropriate allometric relationships, for a 70 kg body mass. This value is higher than those reported for the anesthetized dog and for human subjects. When end-tidal Po2 was gradually decreased from hyperoxia to normoxia, a significant increased in VE due to an increase in breathing frequency was observed, suggesting that the ventilation of the rat is maintained by a considerable 'hypoxic drive' even in normoxia. Furthermore, hypoxic ventilatory depression occurred at a relatively higher Pao2 level (45-60 mm Hg) than in other species. Thus, in the rat, the ventilation vs. end-tidal Po2 curve is shifted to the right compared to other species. After section of the carotid sinus nerve, the hypoxic drive (A) was reduced to 11%, indicating that almost all the ventilatory drive of hypoxia was mediated by the carotid chemoreceptors.

Anesthesia, General↗
PubMed1983

Difference between actions of high PCO2 and low [HCO-3] on neurons in the rat medullary chemosensitive areas in vitro.

To evaluate the contribution of extracellular fluid (ECF) pH in stimulating the ventral medullary chemosensors, effects on neuronal activities of changing ECF PCO2 and/or [HCO-3] were studied in tissue slices taken from the medulla oblongata of the rat. In many cases changes in neuronal discharges produced by a high PCO2-normal [HCO-3] solution differed from those produced by a low [HCO-3] normal PCO2 solution although the ECF pH was reduced to the same degree (from 7.40 to about 7.15). Only 9 of a total of 76 neurons showed an increase in discharge in response to both acid solutions. Neuronal activation due to high PCO2 was augmented when the ECF pH was returned to a normal value (7.40) by simultaneous increase in [HCO-3]. High PCO2-high [HCO-3] solution (pH 7.40) increased the activity of many neurons which were either inhibited or uninfluenced by high PCO2-normal [HCO-3] (pH 7.15). Neuronal activation due to low [HCO-3] was partially suppressed by compensating for the pH reduction with a concomitant decrease in PCO2. The results suggest that CO2 and HCO-3 independently influence the activity of neurons. Possible roles of ECF H+, CO2 and HCO-3 in activating the ventral medullary chemosensitive structures are discussed.

Animals↗
PubMed1983

Transformation of intact yeast cells treated with alkali cations.

Intact yeast cells treated with alkali cations took up plasmid DNA. Li+, Cs+, Rb+, K+, and Na+ were effective in inducing competence. Conditions for the transformation of Saccharomyces cerevisiae D13-1A with plasmid YRp7 were studied in detail with CsCl. The optimum incubation time was 1 h, and the optimum cell concentration was 5 x 10(7) cells per ml. The optimum concentration of Cs+ was 1.0 M. Transformation efficiency increased with increasing concentrations of plasmid DNA. Polyethylene glycol was absolutely required. Heat pulse and various polyamines or basic proteins stimulated the uptake of plasmid DNA. Besides circular DNA, linear plasmid DNA was also taken up by Cs+-treated yeast cells, although the uptake efficiency was considerably reduced. The transformation efficiency with Cs+ or Li+ was comparable with that of conventional protoplast methods for a plasmid containing ars1, although not for plasmids containing a 2 microns origin replication.

Cations, Monovalent↗
PubMed1983

Cloning of the glucokinase gene in Escherichia coli B.

A gene for glucokinase (Glk) in Escherichia coli B was cloned onto vector plasmid pBR322, and the hybrid plasmid obtained was designated pGK100. The gene for Glk was located in the central MluI fragment (0.82 megadalton) of the 6.0-megadalton chromosomal DNA inserted in the HindIII site of the vector. The introduction of pGK100 into E. coli 112L having a decreased level of Glk activity resulted in the about 15-fold increase in this enzyme activity. The poor growth rate of 112L cells on glucose or mannose was also improved by the introduction of pGK100. However, removal of some portion near the glk gene prevented the growth of 112L cells, although Glk activity was high enough to support growth. Therefore, some function of Glk may be regulated by a gene(s) near the glk gene.

Cloning, Molecular↗