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Biomedical subjects

O Watanabe

Publications and source records attributed to O Watanabe.

At least 109 records · Page 6Linked to original sources
PubMed1987

[Apnea test essential in the diagnosis of brain death].

We experienced 11 cases of brain death for the past two years, in six of whom we performed the apnea test to confirm the cessation of the medullary respiratory functions. The cause of brain death was primary intracranial lesions in four, subarachnoidal hemorrhages in three and meningitis in one. Hypoxia of the brain secondary to cardiac arrest resulted brain death in the remaining two cases. Blood gases were analysed before (control) and after pre-oxygenation, after having adjusted PaCO2 around 40 mmHg, and every three minutes after disconnection from the respirator. Blood pressure and other vital signs were monitored through out the test. PaCO2 was brought to 40 mmHg by reducing the respiratory rate in three cases, by decreasing the tidal volume following the reduction of the respiratory rate in one case and by applying the bicarbonate gas in one case. The mean PaCO2 level was 46.2 +/- 6.0 mmHg. No one regained the respiration during 10 minutes of the apnea test. In one case, the oxygen catheter was not inserted deeply enough into the tracheal tube, resulting the fall of blood pressure and necessitating termination of the test six minutes after disconnection from the respirator. This case was not included for further analysis. The pH and PaCO2 did not change significantly after pre-oxygenation and after adjusting of PaCO2. Only the PaO2 increased significantly after preoxygenation. PaCO2 increased with the rate of 3.04 +/- 1.2 mmHg/min up to 73.4 +/- 15.6 mmHg and pH decreased with the rate of 0.016 +/- 0.007 down to 7.1 +/- 0.03 after disconnection from the respirator.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[A case of systemic lupus erythematosus associated with spontaneous bilateral epidural hematomas].

The authors reported a case of systemic lupus erythematosus (SLE) associated with bilateral epidural hematomas which had developed without any recent trauma. A 34-year-old male suddenly suffered from a severe headache and vomited several times. He had no neurological deficits on admission, but CT scans of the head revealed abnormal high density areas over the parieto-occipital regions beneath the calvarium bilaterally. At the operation, fresh epidural clots were removed. There were neither evidence of trauma nor abnormal structures which might have led to the development of the clots. He was discharged a month later, being free from any signs and symptoms. One year later, arthralgia progressed and cutaneous ulceration appeared on his feet. On the second admission, butterfly rash on the face, alopecia, polyarthritis and arthralgia, photosensitivity, systemic purpura and proteinuria were noted. With detailed immunological examinations and renal biopsy, he was diagnosed as SLE. SLE is often associated with neurologic and psychic disorders and there are some cases of intracranial hemorrhage among them. However, the association with epidural hematoma has not been reported to date. We think the degeneration of the dural vessels caused by underlying SLE resulted in the development of these epidural hematomas. We also reviewed the literature about spontaneous epidural hematoma and about bilateral epidural hematomas.

Adult↗
PubMed1984

Acinic cell carcinoma arising in the glossopalatine glands: a report of two cases with electron microscopic observations.

Two cases of acinic cell carcinoma arising in the glossopalatine glands were examined with the electron microscope by means of conventional thin sectioning and freeze-fracturing. Light and electron microscopic observation revealed that the tumors consisted of three types of cells: serous-type, ductlike, and vacuolated cells. Serous-type cells had numerous secretory granules, some of which were discharged into the intercellular spaces. Ductlike cells were smaller, usually lacked secretory granules, and were similar to intercalated duct cells. Vacuolated cells had electron-opaque vacuoles in the cytoplasm. Our findings supported the hypothesis that acinic cell carcinoma may represent a neoplasm of multipotential duct cells which have differentiated mainly into granulated serous cells. Freeze-fracture images of this tumor revealed that tight junctions were composed of ten or more interlinked strands with elongation of basal frontier strands. These findings suggested that the junctional morphology of the tumor resembled that of developing salivary glands and was associated with the degree of cellular differentiation.

Carcinoma↗
PubMed1984

Supramaximal caerulein stimulation and ultrastructure of rat pancreatic acinar cell: early morphological changes during development of experimental pancreatitis.

Rats infused with a supramaximally stimulating dose of the cholecystokinin-pancreozymin analogue caerulein develop acute interstitial pancreatitis (M. Lampel and H.F. Kern. Virchows Arch. A 373: 97-117, 1977). We have studied the early (30-180 min) morphological changes in pancreatic acinar cells induced by infusing caerulein (2.5 micrograms X kg-1 X h-1). The techniques of thin-section electron microscopy, freeze fracture, and enzyme and immunocytochemistry were employed. Shortly (30 min) after the onset of caerulein infusion, large vacuoles appeared in the Golgi area. After longer periods of infusion, these vacuoles further enlarged (probably by fusion with other such vacuoles as well as autophagic vacuoles) and became more widely distributed in the cytoplasm. These large vacuoles were found to be acid phosphatase positive and to be labeled by antibodies directed against digestive zymogens as well as the lysosomal enzyme cathepsin D. These observations indicate that the large vacuoles contain both digestive zymogens and lysosomal hydrolases. During caerulein infusion, morphological evidence of exocytosis at the luminal plasmalemma was reduced or absent, and evidence of basolateral exocytosis was not noted. These studies suggest that secretagogue hyperstimulation with caerulein interferes with the processes involved in condensing vacuole maturation, which normally lead to the separation of digestive zymogens and lysosomal hydrolases. As a result, both types of enzymes remain within the same compartment. This may lead to the intracellular activation of digestive enzymes by lysosomal hydrolases and be an important step in the development of acute pancreatitis.

Acute Disease↗
PubMed1984

Spontaneous calcified tongue lesions in DBA mice.

Large numbers of spontaneously occurring polypoid or slightly elevated lesions were observed in the tongue, mainly the dorsum linguae near the margo linguae, of DBA mice. Histologically the lesion consisted of granulation tissue with focal calcification, and involved superficially the tongue muscle. Often the calcareous deposits were encircled by multinuclear giant cells. The frequency of the calcified tongue lesion was high in lines of DBA/2 (DBA/2NCrj, DBA/2NJcl and DBA/2J), and DBA/1 (DBA/1Jcl and DBA/1J); the SM/J, BALB/c, C57BL/6 and C3H/He strains did not have the lesion. Among hybrid mice, CDF1, a hybrid of DBA/2 and BALB/c, a few had the lesions but no BDF1 mice, a hybrid of DBA/2 and C57BL/6, had any. The frequency was high in the hybrids of DBA/1 and SM/J. These results seem to indicate that the occurrence of the tongue calcified lesions was controlled by polygene.

Animals↗
PubMed1983

The effects of alpha-latrotoxin of black widow spider venom on synaptosome ultrastructure. A morphometric analysis correlating its effects on transmitter release.

The morphological effects of alpha-latrotoxin, the major component of black widow spider venom, were studied quantitatively in a crude synaptosome fraction (prepared from rat brain cortices) which was incubated at 37 degrees C for 10 min in Ringer solutions. Two toxin concentrations were employed, one causing a very large stimulation of transmitter release (approximately 65% and approximately 43% release of [3H]noradrenaline from preloaded synaptosomes, with and without Ca2+ in the incubation buffer), the other 50-60% as active. Incubated synaptosomes, fixed in suspension with aldehydes, were evenly dispersed in agarose before embedding, to assure randomized sampling in the subsequent morphometric analysis. In all the experimental conditions investigated, alpha-latrotoxin treatment caused a significant decrease in the density (number/unit area) of synaptic vesicles in synaptosome profiles. Such an effect was dose-dependent and partially Ca2+-dependent, in good agreement with the data on transmitter release. At high toxin concentration a moderate increase of synaptosome volume and surface area was observed, both with and without Ca2+. Mitochondrial swelling appeared only in synaptosomes treated in Ca2+ containing medium. These effects of alpha-latrotoxin are similar to those described previously at the neuromuscular junction. Thus, the toxin might be a tool of general use for studying vertebrate synapses.

Animals↗
PubMed1983

The effect of alpha-latrotoxin on the neurosecretory PC12 cell line: electron microscopy and cytotoxicity studies.

Neurosecretory PC12 cells were exposed in a variety of experimental conditions to nanomolar concentrations of alpha-latrotoxin purified from the venom of the black widow spider. When applied in a modified Ringer medium containing millimolar Ca2+ the toxin rapidly elicited a marked stimulation of exocytosis, as indicated by the appearance of typical images of granule-plasmalemma interaction and by the decreased density (number/unit area) of secretion granules in the cytoplasm. Without Ca2+ in the medium this early toxin effect was delayed and evolved less rapidly, but was still clearly appreciable. These morphological results appear in good quantitative agreement with the biochemical data on dopamine release reported in the preceding article. The stimulation of exocytosis was followed after a short delay by a stimulation of endocytosis, as revealed by an increased accumulation of the extracellular tracer, [14C]sucrose, within the toxin-treated cells. At later times after the application of alpha-latrotoxin other effects appeared, but only in the presence of Ca2+: these included changes in cell shape; focal alterations of the mitochondrial matrix (clear discrete areas and dense precipitates) and frank signs of cytotoxicity (rupture of the plasmalemma, clearing of the cytoplasmatic matrix). The toxin-induced cell death was studied quantitatively by using trypan blue exclusion as well as the 51Cr test, and was found to be dependent on alpha-latrotoxin concentration, temperature of incubation and Ca2+ concentration in the medium. Ionic substitutions concerning anions as well as cations other than Ca2+ had minor or no consequences. Thus, the early effect of alpha-latrotoxin in PC12 cells (stimulation of exocytosis, at least partially Ca2+-independent) can be dissociated from the late 'toxic' effect (strictly Ca2+-dependent).

Animals↗
PubMed1982

Effects of glucagon on myoelectrical activity of the stomach of conscious and anesthetized dogs.

Effects of glucagon on gastric electrical and mechanical activities recorded by means of a chronically implanted suction electrode and a force strain gauge transducer were examined in conscious and anesthetized dogs. Glucagon (1-10 micrograms/kg) induced inhibition of gastric electrical activity together with mechanical activity in conscious dogs. The plasma glucagon level following exogenous glucagon administration which induced the inhibitory effects on electrical and mechanical activities was over 5 ng/ml. alpha- and beta-adrenoceptor blocking agents did not significantly alter the inhibitory effect of glucagon. Changes in plasma concentrations of glucose, cAMP, insulin, gastrin and catecholamines after glucagon administration were not correlated with the inhibitory action of glucagon on the gastric electrical and mechanical activities. Glucagon at higher concentrations (10(-6) -5 x 10(-6) g/ml) did not produce appreciable changes in motility of the canine gastric strips in vitro. In an anesthetized condition, the inhibitory action of glucagon was completely abolished. Results indicate that exogenously applied glucagon possibly acts directly on the central nervous system, and thus resulted in the inhibition of the gastric electrical and mechanical activities.

Action Potentials↗
PubMed1980

The role of gastric glucagon immunoreactivity in pancreatectomized dogs.

Immunoreactive glucagon (IRG) or glucagon immunoreactivity is known to be increased in the plasma of insulin-deprived pancreatectomized dogs, most of it originating in the stomach. We attempted to clarify the extent to which gastric IRG is involved in glycogenolysis in the liver of insulin-deprived, pancreatectomized dogs. Mongrel dogs underwent total pancreatectomy. IRG levels in portal vein blood increased to 760 +/- 186 pg/ml on the 4th postoperative day while the insulin levels were negligible. On the 4th postoperative day some of the dogs underwent total gastrectomy. IRG levels in the portal vein blood of pancreatectomized dogs decreased from 760 +/- 186 pg/ml to 135 +/- 44 pg/ml one hour after gastrectomy. Glucose containing insulin was then infused into both pancreatectomized and pancreatectomized-gastrectomized grups of dogs. Glycogen synthesis in the liver during glucose and insulin infusion was much the same in both groups. However, glycogen degradation after glucose and insulin infusion was completely suppressed in pancreatectomized dogs without a stomach while pancreatectomized dogs alone showed marked glycogenolysis in the liver. No difference in portal IRI and blood sugar level was found in both groups while a marked difference in portal IRG were observed. These findings indicate that the IRG released from the stomach plays a significant role i glycogen metabolism in pancreatectomized dogs.

Animals↗