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Biomedical subjects

A Takeuchi

Publications and source records attributed to A Takeuchi.

At least 505 records · Page 28Linked to original sources
PubMed1978

Electron microscopy observations on Trypanosoma brucei: freeze-cleaving and thin-sectioning study of the apical part of the flagellar pocket.

Observations on the apical part of the flagellar pocket of Trypanosoma brucei using the freeze-cleaving and thin-sectioning techniques of electron microscopy are reported. The flagellar pocket is shown as a flask-shaped depression in the body, continuous with the pellicle and flagellar sheath. The membranes of the apical part of the pocket on the flanged side of the body compress the flagellar sheath, forming part of a "neck region". This region is completed on the broad body side of the flagellar pocket when it embraces the flagellar sheath. The possible role of the neck region in the dynamic function of pinocytosis is discussed.

Animals↗
PubMed1978

Congenital fistula of the right coronary artery-left ventricle--a case report.

While the incidence of right coronary artery-left ventricle fistulae is low, cardiac catheterization, ascending aortogram and selective coronary angiogram led us to suspect the presence of such a fistula in a 10-year old female patient. Arteriorrhaphy with additional ligation was performed and the patient is in good health more than one year after surgery.

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PubMed1978

Effects of membrane potential and temperature on the excitatory post-synaptic current in the crayfish muscle.

1. Effects of membrane potential and temperature on the excitatory post-synaptic current (e.p.s.c.) were studied in the voltage-clamped crayfish muscle. E.p.c. was recorded either by measuring the feedback current through an intracellular wire electrode or by focal recording with an extracellular micro-electrode. 2. The amplitude of the e.p.s.c. obtained by the voltage clamp method varied almost linearly with membrane potential between -100 mV and +70 mV, whilst the reversal potential was +23.8 +/- 3.9 mV (S.E. of mean). 3. The declining phase of the extracellular e.p.s.c. was slightly prolonged by depolarization and shortened by hyperpolarization. Potential dependence of the decay time constant was expressed by tau = a exp (AV), with a = 2.78 msec and A = 0.0037 mV-1. 4. The decay time constant had a Q10 of 2.3 and the growth time had a Q10 of 1.5. 5. The voltage dependence of the decay phase of the e.p.s. was the reverse of that found in frog end-plate. It is concluded that the voltage dependence of the time course is not related either to the charge of ions which carry the synaptic current or to the charge of the transmitter.

Animals↗
PubMed1978

Scanning and transmission electron microscopic study of Escherichia coli O15 (RDEC-1) enteric infection in rabbits.

RDEC-1 is a piliated strain of Escherichia coli that was isolated from and produces diarrhea in rabbits without invading the mucosa or synthesizing one of the classical enterotoxins. Previous histological and fluorescent-antibody studies of RDEC-1 diarrhea revealed an acute inflammatory response and large numbers of RDEC-1 associated with (adhering to) the mucosal surface of the ileum, cecum, and colon. The purpose of the present investigation was to further elucidate the histopathology by scanning (SEM) and transmission (TEM) electron microscopy. SEM revealed aggregates of bacteria on the surface of the gut; their distribution was patchy in the ileum and diffuse in the cecum and colon. Bacteria were in contact with each other and appeared to be closely associated with the epithelial surface. TEM showed that the brush border region of the epithelial cells was found to be in varying stages of degeneration, and the bacteria could not be seen adhering to the mucosal cells unless the brush border was absent. Bacteria were in close contact only with epithelial cells that had lost their brush border. The space between the bacteria and the epithelial cells was 11 nm, and it appeared to be filled, in most cases, with densely stained material. This E. coli rarely penetrated epithelial cells, but when it did; it was found in the supranuclear region and never reached the lamina propria. From previous and present studies, it seems probable that RDEC-1 produces diarrhea in rabbits by a mechanism that may be cytotoxic and differs from the classic mechanisms by which E. coli produces diarrhea.

Animals↗
PubMed1978

Experimental infection of mouse peritoneal mesothelium with scrub typhus rickettsiae: an ultrastructural study.

The infection cycle of Rickettsia tsutsugamushi in mouse peritoneal mesothelial cells, observed late in the course of an established infection, intimately involved the host cell plasma membrane. Organisms multiplied in the cytoplasm, moved to the cell periphery, and acquired a host-membrane coat as they budded from the cell surface. Rickettsiae enveloped by this membrane entered other mesothelial cells, apparently by a phagocytic mechanism. Organisms escaped from the phagocytic vacuole as the vacuole membrane and host membrane coat disintegrated. Free rickettsiae replicated by binary fission in the cell cytoplasm. Rickettsial infection of mesothelial cells induced conspicuous cellular hypertrophy with increased numbers of unaltered cytoplasmic organelles.

Animals↗
PubMed1978

Effect of thyroidectomy on the secretory profiles of growth hormone, thyrotropin and corticosterone in the rat.

Changes in pituitary hormone secretions following thyroidectomy were examined in sequentially collected blood samples every 15 min day and night for 7 hr from male rats via cannulae into the right atria. Pulsatile growth hormone secretions were observed every 2.5 or 3.5 hr in normal rats, while thyroidectomy 3 weeks prior to experiments abolished the growth hormone burst. Corticosterone profiles from normal rats showed also episodic patterns which were more often observed in the night experiment. The eisodic secretion of corticosterone seemed to inhibit the subsequent growth hormone burst but not vice versa. The interrelation between integrated concentrations of growth hormone and corticosterone showed a negative correlation although the coefficient was not statistically significant. After thyroidectomy, the basal level of corticosterone decreased and the episodic secretion was blunted. There was no nyctohemeral variation in the plasma thyrotropin level in normal rats but small and slow fluctuations. Thyroidectomy caused about ten-fold elevation in the basal thyrotropin level and, in addition to this, a decrease at 1500 hr and an increase during the night, followed thereafter by a decreasing tendency to 0400 hr. Power spectral analysis revealed smaller components in growth hormone secretion of normal rats, which had periods of 60, 40 and 36 min, besides the hormone burst. The spectral analysis also made it clear that there were small and frequent components (40 or 36 min period) in corticosterone secretion.

Animals↗
PubMed1977

Effect of acute exposure to cold on the levels of corticosterone and pituitary hormones in plasma collected from free conscious cannulated rats.

To investigate the initial response of the pituitary and adrenal cortex functionings of rats acutely exposed to cold, we developed a technique for cannulation which allowed sequential blood collection from conscious and freed rats. Two cannulae were inserted, one into the carotid artery used for collection and the other into the femoral vein for blood transfusion to keep the blood volume constant. Significant increases in plasma corticosterone and thyrotropin were evoked within 15 min after exposure. While plasma growth hormone (GH) slightly decreased, and the prolactin level tended to fall by 1 hr after cold exposure but the difference was not significant as compared with control values.

Animals↗