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Biomedical subjects

H Satoh

Publications and source records attributed to H Satoh.

At least 541 records · Page 30Linked to original sources
PubMed1993

Effects of taurine on Ca2+ currents in young embryonic chick cardiomyocytes.

The effects of taurine on L-type and T-type Ca2+ channels is isolated 3-day-old embryonic chick heart cells were examined at different intracellular Ca2+ concentrations ([Ca]i), using whole-cell voltage clamp techniques. Experiments were performed at room temperature (22 degrees C) and at a holding potential of -40 mV. When [Ca]i was pCa 7, addition of taurine to the bath solution reduced the L-type Ca2+ current (ICa(L)) at 0 mV by 56.3 +/- 2.8% (n = 5, P < 0.01) at 10 mM, and by 73.2 +/- 2.6% (n = 5, P < 0.001) at 20 mM. At pCa 10, ICa(L) was unaffected (7.2 +/- 3.1%, n = 5, P > 0.05) by 10 mM taurine and was enhanced by 47.3 +/- 2.4% (n = 5, P < 0.01) by 20 mM taurine. Control fast and slow time constants of inactivation at pCa 7 (at +10 mV) were 5.8 +/- 2.8 ms and 28.8 +/- 1.8 ms (n = 4), respectively; neither constant was modified by taurine. At pCa 10, the control fast and slow time constants were 15.8 +/- 1.0 and 67.7 +/- 3.8 ms (n = 4); the fast time constant was not affected by 10-20 mM taurine but the slow time constant was slowed by 14.5 +/- 2.9% (n = 4, P < 0.05) by 10 mM taurine and by 66.2 +/- 2.8% (n = 4, P < 0.001) by 20 mM taurine. The inactivation curve for ICa(L) was not modified by taurine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Suppression of tumorigenicity of A549 lung adenocarcinoma cells by human chromosomes 3 and 11 introduced via microcell-mediated chromosome transfer.

To map tumor suppressor genes for lung adenocarcinomas, we introduced normal human chromosomes 3, 7, and 11 into the A549 tumor cell line by microcell-mediated chromosome transfer to test which chromosomes had the ability to suppress tumorigenicity. These human chromosomes, which contain the neomycin gene as a selectable marker, were transferred into A549 lung adenocarcinoma cells at frequencies of 0.3-1.8 x 10(-6). Two microcell hybrid clones with an introduced chromosome 3, two with an introduced chromosome 7, and six with an introduced chromosome 11 were isolated and examined for their growth properties and tumorigenicity in nude mice. Whereas parental A549 cells formed tumors with an average latency of 68 d, both microcell hybrids with an introduced chromosome 3 failed to form tumors for over 360 d. Similar tumorigenicity results were obtained when the clones were implanted into denuded tracheas, a more orthotopic transplantation site. The two clones with an introduced chromosome 7 were still tumorigenic; they formed tumors within 100-123 d after injection and grew progressively, although the tumors grew slightly slower than the parental cells did. Among the six clones with an introduced chromosome 11, one clone was still highly tumorigenic but did not contain an extra copy of an intact introduced chromosome 11. Three clones with a single intact copy of introduced chromosome 11 formed tumors with latency periods significantly longer than those of the parental cells. Two clones had two copies of the introduced chromosome 11, and both failed to form tumors within 1 yr of injection. These results indicate that chromosomes 3 and 11 can suppress the tumorigenicity of A549 lung adenocarcinoma cells.

Adenocarcinoma↗
PubMed1993

Subjective symptoms and neurobehavioral performances of ex-mercury miners at an average of 18 years after the cessation of chronic exposure to mercury vapor. Mercury Workers Study Group.

In order to determine if there are any residual effects of long-term exposure to mercury vapor, neurobehavioral tests were given to ex-mercury miners about 18 years after the cessation of mercury exposure. Seventy-six male ex-mercury miners who had been exposed to relatively high concentrations of mercury vapor (over 1.0 mg/m3) and with a past history of mercury intoxication were compared to age (+/- 3 years)-, sex-, and years of education-matched controls. Although the extent of the workers' symptoms caused by mercury poisoning, termed erethismus merculialis, markedly decreased after the cessation of exposure, the prevalence of neurological symptoms (such as hand tremors, headaches, and slurred speech) and symptoms of senility (such as low-back pain, loss of sexual desire) in the ex-miners was significantly higher than those in the controls. Matched-pair analysis showed that performances of motor coordination, Simple reaction time, and Short-term memory in the ex-miners were significantly deteriorated compared to those of controls. There are slight but persistent effects on neurobehavioral function, especially on motor coordination function, among mercury miners more than 10 years after the cessation of exposure.

Aged↗
PubMed1993

Electrophysiological actions of adenosine and aminophylline in spontaneously beating and voltage-clamped rabbit sino-atrial node preparations.

Effects of adenosine (30 to 200 mumol/l) on the spontaneous action potentials and the membrane currents in rabbit sino-atrial node (SA) preparations were examined. Adenosine (30 mumol/l) lengthened the action potential duration and the cycle length. At 100 mumol/l, adenosine also hyperpolarized the maximum diastolic potential. However, the action potential amplitude and the maximum rate of depolarization Vmax) were unaffected. In the presence of adenosine (200 mumol/l), addition of aminophylline (an antagonist) (23-46 mumol/l) shortened the cycle length and depolarized the maximum diastolic potential to the contrary. Aminophylline did not antagonize the prolongation of the action potential. Aminophylline (46 mumol/l) alone decreased the cycle length and the maximum diastolic potential, but did not affect the action potential amplitude, the action potential duration and the Vmax. In the presence of aminophylline (46 mumol/l), addition of adenosine (200 mumol/l) increased the cycle length and the action potential duration, and decreased Vmax. In voltage-clamp experiments, adenosine greatly shifted the background current in the outward direction. Holding potential was -40 mV. Adenosine reduced a slow inward and a time-dependent outward current, in a concentration-dependent manner. Adenosine did not affect the time constant of inactivation phase and the voltages of the half-maximum activation and inactivation for the slow inward current. The activation curve for the outward current was also unaffected. A hyperpolarization-activated inward current was decreased. In the presence of aminophylline (46 mumol/l), adenosine (200 mumol/l) decreased the slow inward current, the time-dependent outward current and the hyperpolarization-activated inward current.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1993

Pseudarthrosis and delayed union after anterior cervical fusion.

Anterior cervical spine fusion was carried out on 443 cases between 1965 and 1988 with pseudarthrosis or delayed union in 15 (3.4%). The causes of these complications were malalignment and faulty postoperative care. Symptoms resulted from abnormal mobility, cord compression due to posterior slip or rotation of the upper vertebral body, kyphotic deformity or a problem at the adjacent level. Four out 5 cases with symptoms recovered successfully after a second operation.

Adult↗
PubMed1993

Percutaneous pneumatic balloon dilation of the obstructed pancreaticojejunal anastomosis in the management of a case of intractable pancreatic cutaneous fistula.

In the treatment of postoperative pancreatic cutaneous fistula, various non-surgical techniques are recommended due to the potential complications from repeated operation in the presence of marked inflammatory changes and adhesions. We describe herein the case of a 70-year-old Japanese man with an intractable pancreatic cutaneous fistula following pancreatoduodenectomy, in whom successful treatment was achieved through percutaneous pneumatic balloon dilation of the obstructed pancreaticojejunal anastomosis. Non-surgical percutaneous intervention may be a useful modality to treat an intractable external pancreatic fistula in accordance with the underlying cause of fistula formation.

Aged↗
PubMed1993

Mercury and selenium contents in amyotrophic lateral sclerosis in Hokkaido, the northernmost island of Japan.

We evaluated the pathogenicity of mercury (Hg) and selenium (Se) which are supposed to be one of the risk factors in the development of amyotrophic lateral sclerosis (ALS). Hg and Se contents were measured in plasma, blood cells, scalp hair samples of 21 sporadic ALS patients and 36 controls, who included 19 patients with other neurological diseases, in Hokkaido, the northernmost island of Japan. Hg and Se levels in plasma and blood cells of ALS patients were significantly lower in advanced staged ALS patients than controls. Low Hg and Se contents in ALS, being correlated with their disabilities and nutritional conditions, would rather reflect the disease contracted states than the pathogenic roles in ALS.

Adult↗
PubMed1993

Spontaneous rupture of craniopharyngioma cysts. A report of five cases and review of the literature.

Reports of spontaneous rupture of a craniopharyngioma cyst are extremely rare. Five cases of spontaneous rupture of a craniopharyngioma cysts are reported. Clinical symptoms included chemical meningitis in three patients, alleviation of headache in one, and improvement in a visual disturbance in one. Reduction in cyst size was confirmed by computed tomography or magnetic resonance imaging in three of five patients, and the histopathological diagnosis was confirmed histologically in four patients. Cerebrospinal fluid findings were abnormal in the three patients with chemical meningitis. Spontaneous rupture of craniopharyngioma cysts tended to occur more frequently in adult males. Computed tomography and magnetic resonance imaging were useful in diagnosing cyst rupture, and cerebrospinal fluid findings, especially the presence of cholesterol crystals and an elevated cholesterol concentration, are suggestive, even when no reduction in cyst size is observed radiologically.

Adolescent↗
PubMed1993

Primary malignant rhabdoid tumor of the central nervous system: case report and review of the literature.

Malignant rhabdoid tumor (MRT) is well known as a pediatric malignant tumor of the kidney. Only nine cases of primary MRT of the central nervous system (CNS) have been reported. We are reporting in detail the clinical course and treatment of a patient with primary MRT of the CNS. We cared for a 3-year-old girl with an MRT that extended from the internal auditory canal to the cerebellopontine angle. Despite three surgical attempts at resecting the tumor combined with whole craniospinal axis irradiation, as well as chemotherapy consisting of intravenous nimustine hydrochloride and intrathecal methotrexate injections, the patient died 13 months after her initial hospitalization. The origin of CNS-MRT development is still a question of pathologic debate. Like renal MRT, the prognosis of MRT of the CNS is very poor. The dissemination of MRT of the CNS occurred in most cases.

Brain Neoplasms↗
PubMed1993

Morphological and electrophysiological changes induced by calcium ionophores (A23187 and X-537A) in spontaneously beating rabbit sino-atrial node cells.

1. Effects of calcium ionophores (A23187 and X-537A) on the spontaneously beating sino-atrial (SA) node cells of rabbit heart were examined using electron microscopic and an electrophysiological techniques. 2. During exposure to A23187 or X-537A (2 x 10(-5) M), the cycle length was significantly prolonged by 11% (n = 12) or 118% (n = 11), respectively. But neither ionophore affected other action potential parameters. 3. X-537A (2 x 10(-5) M) induced irregular rhythm (dysrhythmia), probably due to cellular calcium overload. Similarly, ouabain (3 x 10(-7) M) also elicited dysrhythmia. In the presence of isoproterenol (ISP, 10(-7) M), X-537A potentiated dysrhythmia, and A23187 newly induced it. 4. In ultrastructural analyses, X-537A caused swelling of the cisternae of Golgi apparatus within 10 min, whereas A23187 and ouabain did not produce any changes even after 30 min-application. 5. Addition of high Ca2+ (10 mM) and/or ISP (10(-7) M) to X-537A produced a further dilation and vacuolization. In A23187 or ouabain, however, the addition of Ca2+ and ISP did not cause any changes, even during dysrhythmia. 6. These results indicate that X-537A elicited a more potent calcium overload than A23187, and that a discrepancy between ultrastructural damages and electrical changes exists.

Animals↗
PubMed1993

Caffeine depression of spontaneous activity in rabbit sino-atrial node cells.

1. Effects of caffeine on the action potentials and the membrane currents in spontaneously beating rabbit sino-atrial (SA) node cells were examined using a two-microelectrode technique. 2. Cumulative administrations of caffeine (1-10 mM) caused a negative chronotropic effect in a concentration-dependent manner, which was not modified by atropine (0.1 microM). At 10 mM, caffeine increased the amplitude and prolonged the duration of action potentials significantly; the other parameters were unaffected. 3. In 3 of 16 preparations, caffeine (5 mM) elicited arrhythmia. At high Ca2+ (8.1 mM), caffeine (5 mM) increased the incidence of arrhythmia. 4. Caffeine (0.5-10 mM) enhanced the slow inward current, but at 10 mM decreased the enhanced peak current by 5 mM. The hyperpolarization-activated inward current was also enhanced by caffeine, but 10 mM caffeine decreased the current peak as compared with that at 5 mM. In addition, caffeine inhibited the delayed rectifying outward current in a concentration-dependent manner, accompanied by a depressed activation curve without any shift in the half-maximum activation voltage. 5. Caffeine elevated the cytoplasmic Ca2+ level in the SA node cells loaded with Ca(2+)-sensitive fluorescent dye (fura-2). 6. These results suggest that caffeine enhances and/or inhibits the ionic currents and elicits arrhythmia due to the induction of cellular calcium overload.

Action Potentials↗
PubMed1993

Comparative electrophysiological and mechanical actions of ATP-sensitive potassium channel openers in canine Purkinje fibers.

1. Electrophysiological and mechanical effects of ATP-dependent potassium channel openers on canine Purkinje fibers were examined. 2. Cromakalim and pinacidil (0.3-10 microM) and nicorandil (0.3-1 mM) shortened the action potential duration (APD), and reduced the contractile force, in a concentration-dependent manner. Other action potential parameters were unaffected. The effects were reversible. 3. Effects of the openers were antagonized by tetraethylammonium (a non-specific potassium channel blocker) and more potently by glibenclamide (a blocker of ATP-sensitive K+ channel). 4. The APD shortening and the negative inotropic effect induced by a switch of stimulation frequency (from 0.5 to 3 Hz) were potentiated by the openers. At high Ca2+ (5.4 and 10.8 mM), the effects of the openers on the APD and contractile force were unaffected. 5. In the spontaneously beating preparations, the openers hyperpolarized the maximum diastolic potential, and an arrest occurred. 6. Under the calcium overload condition, the K+ openers abolished a delayed after depolarization, and enhanced the depressed post-rest potentiation. 7. These results suggest that the K+ channel openers increase the K+ conductance and might decrease the cellular Ca2+ level in calcium overloading cells, and that nicorandil might also act directly ATP-sensitive K+ channels.

Action Potentials↗
PubMed1993

Modulation of the automaticity by histamine and cimetidine in rabbit sino-atrial node cells.

1. Effects of histamine (HIS) and cimetidine (CIM) on the spontaneous action potentials and ionic currents in rabbit sino-atrial node cells were investigated. 2. HIS accelerated the sinus rate at 10 mumol/l, and shortened the action potential duration (APD) at 100 mumol/l, significantly. The positive effects were blocked by CIM (100 mumol/l), but not by diphenhydramine (DPH, 1 mumol/l). HIS (100 mumol/l) elicited a dysrhythmia in 4 out of 10 preparations. Addition of acetylcholine (ACh) (1 mumol/l) depressed the HIS-induced effects, but dysrhythmia occurred in 5 of 10 preparations. 3. CIM (100 mumol/l) caused a negative chronotropic effect. The APD was prolonged, and the Vmax was decreased. Addition of pindolol (0.1 mumol/l) potentiated the depressions. CIM (3 mmol/l) caused a sinus arrest in 3 out of 7 preparations. 4. In voltage-clamp experiments, HIS (100 mumol/l) enhanced the slow inward current (Isi). The delayed rectifying K+ current (IK) and hyperpolarization-activated inward current (Ih) were also increased. The enhancement was inhibited by CIM (100 mumol/l), but not by DPH (1 mumol/l). CIM (100 mumol/l) alone depressed Isi, IK and Ih. Pindolol (0.1 mumol/l) potentiated the CIM-induced depressions significantly. 5. These results suggest that HIS and CIM would modulate the ionic currents mediated through H2-receptors, and that HIS possesses arrhythmogenic action (probably by cAMP accumulation), which is potentiated by ACh.

Action Potentials↗
PubMed1993

Positive and negative chronotropic effects of caffeine in spontaneously beating rabbit sino-atrial node cells.

1. Effects of caffeine on the automaticity in spontaneously beating rabbit sino-atrial node cells were examined. 2. Caffeine (0.5-2 mM) caused only a positive chronotropic effect. At over 5 mM, caffeine caused an initial positive and subsequently a negative chronotropic effect. Both were not modified by pindolol (1 microM) and atropine (1 microM). 3. At 10 mM, a dysrhythmia occurred in all 9 preparations. The effects were reversible, and dysrhythmia also disappeared after washout. 4. When extracellular K+ was increased from 2.7 to 8 mM, the dysrhythmia induced by caffeine (10 mM) was abolished, and the sinus rate was increased. 5. Addition of tetrodotoxin (TTX) (10(-7) M) in the presence of caffeine (10 mM) also abolished the dysrhythmia and increased the sinus rate. 6. In addition, a decrease in extracellular Ca2+ ([Ca]o) to 0.5 mM abolished the dysrhythmia and increased the sinus rate, whereas increasing [Ca]o to 7.4 mM potentiated the negative chronotropic effect and failed to inhibit the dysrhythmia. 7. These results indicate that the positive chronotropic effect is due to the stimulatory effect of caffeine, and the negative effect is directly and indirectly due to development of cellular calcium overload.

Action Potentials↗
PubMed1993

Arrhythmogenic actions of class III antiarrhythmic drugs in spontaneously beating rabbit sino-atrial node cells.

1. Arrhythmogenic actions induced by class III antiarrhythmic drugs (amiodarone, bretylium and sotalol) in spontaneously beating rabbit sino-atrial node cells were investigated by using a two microelectrode voltage-clamp technique. 2. Amiodarone (10(-6) mol/l) caused a negative chronotropic effect. Dysrhythmias at 10(-5) mol/l occurred in 3 out of 10 preparations. Amiodarone elicited a transient inward current. After wash out, the regular rhythm was resumed and the transient inward current also disappeared. 3. Bretylium (10(-5) mol/l) also induced dysrhythmias more often (in 5 of 11 preparations). Sotalol (10(-5) mol/l) caused dysrhythmias in only 1 of 10 preparations. 4. Changes in the cytosolic Ca2+ concentration in single sino-atrial node cells were monitored with fura-2, a Ca(2+)-sensitive fluorescent dye. Amiodarone (3 x 10(-5) mol/l) and bretylium (10(-5) mol/l) elevated the cytosolic Ca2+ level significantly, but sotalol even at 10(-3) mol/l did not affect it. 5. These results indicate that class III antiarrhythmic drugs possess arrhythmogenic actions, probably resulting from elevation of cellular Ca2+ concentration due to direct and indirect actions.

Action Potentials↗
PubMed1993

Bladder carcinoma producing granulocyte colony-stimulating factor: a case report.

A 67-year-old man with squamous cell bladder carcinoma showed remarkable leukocytosis (maximum 50,300 per microliter.) for 4 months while the neoplasm recurred and metastasis progressed. The patient died of systemic metastasis within 9 months after cystectomy. Enzyme immunoassay of the serum demonstrated remarkably high levels of granulocyte colony-stimulating factor (4,928 pg./ml.). Immunohistochemical examination with anti-granulocyte colony-stimulating factor monoclonal antibody demonstrated granulocyte colony-stimulating factor production in the metastatic cancer cells in the liver. The expression of the granulocyte colony-stimulating factor gene in the tumor specimens was examined by standard Northern blot analysis. Specific granulocyte colony-stimulating factor transcript was identified in the total ribonucleic acid fraction extracted from a tumor specimen of the peritoneal metastatic lesion. These results indicated that the autonomous production of granulocyte colony-stimulating factor in this bladder carcinoma induced paraneoplastic leukocytosis.

Aged↗
PubMed1993

Autonomous replication of human chromosomal DNA fragments in human cells.

We have examined whether a human chromosome has distinct segments that can replicate autonomously as extrachromosomal elements. Human 293S cells were transfected with a set of human chromosomal DNA fragments of 8-15 kilobase pairs that were cloned on an Escherichia coli plasmid vector. The transfected cells were subsequently cultured in the presence of 5-bromodeoxyuridine during two cell generations, and several plasmid clones labeled in both of the daughter DNA strands were isolated. Efficiency of replication of these clones, as determined from the ratios of heavy-heavy and one-half of heavy-light molecules to total molecules recovered from density-labeled cells, was 9.4% per cell generation on the average. Replication efficiency of control clones excluded during the selection was about 2.2% and that of the vector plasmid alone was 0.3%. A representative clone p1W1 replicated in a semiconservative manner only one round during the S phase of the cell cycle. It replicated extrachromosomally without integration into chromosome. The human segment of the clone was composed of several subsegments that promoted autonomous replication at different efficiencies. Our results suggest that certain specific nucleotide sequences are involved in autonomous replication of human segments.

Blotting, Southern↗