Biomedical subjects

N Ogata

Publications and source records attributed to N Ogata.

At least 217 records · Page 12Linked to original sources

PubMed1989

[Pathologic response of the retinal pigment epithelium. The effect of mucopolysaccharide in the subretinal space to phagocytosis. Part 5].

Previously we reported that retinal pigment epithelial cells (RPE) showed different phagocytotic activity according to the charge characteristics of the surface of polystyrene particles which were injected into the subretinal space of albino rats. In this study we examined whether subretinal mucopolysaccharide controls RPE phagocytosis or not, using positive or negative charged particles (3 microns in diameter). The technique of ruthenium red staining, a cationic dye, was employed with special efforts to detect the relationship between acid mucopolysaccharide and particles at the electron microscopic level. Six hours after injection of the positive charged particles, the ruthenium red staining revealed fine granular electron-dense materials, coating the surfaces of many small substances surrounding polystyrene particles which were not yet phagocytized by RPE. On the other hand, there was no staining of negative ones which were already phagocytized by RPE. At 24 hours, no staining was observed on the surface of either particles. These findings suggest that an anionic property of mucopolysaccharide in the subretinal space controls the phagocytosis of RPE.

Animals↗

PubMed1989

Kinetics of chlorpromazine block of sodium channels in single guinea pig cardiac myocytes.

Block of sodium current by chlorpromazine in single ventricular myocytes isolated from guinea pigs was studied using the whole cell patch clamp technique. Chlorpromazine in micromolar concentrations reduced the amplitude of peak sodium current associated with step depolarizations from a holding potential of -140 mV. Concentration-response curves obtained with a holding potential of -140 mV were best fit by a 2:1 stoichiometry, and were shifted in the direction of lower concentrations when a holding potential of -100 mV was used. In agreement with this observation, the steady-state inactivation curve was shifted to more negative potentials by chlorpromazine. The block was not associated with any change in the time course of sodium current activation or inactivation during a depolarizing step. Chlorpromazine also produced marked use-dependent block as demonstrated by a cumulative increase in the block during a train of depolarizing pulses. This use dependence was due to a higher affinity of chlorpromazine for the inactivated state of sodium channels than for the resting state and to a very slow repriming of the drug-bound sodium channels from inactivation. These blocking actions could contribute to the antiarrhythmic effects of chlorpromazine at low concentrations and to the cardiotoxic effects at high concentrations.

Animals↗

PubMed1989

[The state of the recall visit at the pediatric dentistry clinic of Nagasaki University Dental Hospital].

The purpose of this study is to discover the actual condition and the state of the recall visit of the patients who appeared at the Pediatric Dentistry Clinic of Nagasaki University Dental Hospital, and to compare the results of 1987 and 1985. Concerning the making of appointments for the recall visit, we sent cards to patients in 1987 though, in 1985 we did not send cards to the patients so the patients themselves had to make a telephone call to arrange an appointment. The results were as follows: 1) The rate of the patients who were making their first time recall visit increased by means of sending cards to patients. 2) Of the total number of 493 patients who appeared at our clinic in 1985, 127 (25.8%) did not finish their dental treatment and stopped visiting our clinic for treatment. 3) The rate of the patients who finished their dental treatment and were making the first time recall visit was 69.9% in 1987. 4) The average ages of the patients were 6 years 5 months in 1987 and 5 years 6 months in 1985. The lower the age of patients, the higher the rate of the recall visits, while the rate of pre-school children was higher than that of school children. 5) The rate of the patients who finished their dental treatment and made recall visits was higher in cases in which the chief complaints of the first visit were caries prevention (86.2%) and caries treatment (71.3%) than the cases of tooth extraction (50%), tooth shape anomalies (50%) and tooth pain (50.5%). 6) There was no significant difference in the number of caries decayed teeth at the first oral examination between the group of patients making their first recall visit and the group of patients rejecting a recall visit. 7) In the case of the patients to whom space retainers and orthodontic appliances were applied, the rate of making recall visits decreased more in 1987 than that of 1985. 8) There was no difference in the rate of those making their first time recall visit between the two categories of diseased children and nondiseased children.

Appointments and Schedules↗

PubMed1989

Analysis of beechwood creosote by gas chromatography-mass spectrometry and high-performance liquid chromatography.

Compounds in beechwood creosote were analyzed by gas chromatography-mass spectrometry, and 22 major constituents were identified. Of these, 19 were phenolic compounds, i. e., guaiacol, phenol, two cresol isomers, four methylguaiacol (creosol) isomers, six xylenol isomers, two trimethylphenol isomers, 4-ethylguaiacol, 4-ethyl-5-methylguaiacol, and 4-propylguaiacol. The remaining three were hitherto unpredicted five-membered ring compounds, i. e., 3-methyl-2-hydroxy-2-cyclopenten-1-one, 3,5-dimethyl-2-hydroxy-2-cyclopenten-1-one, and 3-ethyl-2-hydroxy-2-cyclopenten-1-one. The relative quantities of these compounds were also compared with those obtained by high-resolution high-performance liquid chromatography. This report probably represents the first extensive analysis of beechwood creosote.

Carcinogens↗

PubMed1989

[A case of radiation myelitis following radiotherapy in lung cancer].

A case of radiation myelitis developed 1 year and 5 months after radiotherapy for lung cancer is reported. A 75-years old male was given a dose of 70 Gy to the tumor with a fraction dose of 2 Gy, 5 times per week. He developed the weakness and disturbance of sense in bilateral lower extremities, which gradually worsened in spite of a variety of treatment. Some discussions on tolerance dose, fraction dose and fraction number are made as well as technique of irradiation.

Aged↗

PubMed1989

[A case of Pickwickian syndrome treated by implantation of a cardiac permanent pacemaker].

A 41-year-old male was admitted to our hospital with congestive heart failure and bronchopneumonia. During hospitalization extreme sinus bradycardia, sinus arrest up to 6.2 seconds and high grade AV block were observed to occur simultaneously with apneic episodes of ECG monitoring. After that, a diagnosis of Pickwickian syndrome was made in this obese patient. In spite of weight reduction, change of sleep position and acetazolamide administration, obstructive sleep apnea and severe bradyarrhythmias were not improve. These severe bradyarrhythmias and ventricular tachyarrhythmias may be one cause of the not infrequent sudden deaths in patients with this Pickwickian syndrome. In addition to the tracheostomy, we propose that implantation of a cardiac permanent pacemaker should be selected for the bradyarrhythmias in association with the Pickwickian syndrome.

Adult↗

PubMed1989

[Pathologic response of the weak damaged retinal pigment epithelium (RPE)--affected by sodium iodate (NaIO3)].

We examined the cellular responses of the retinal pigment epithelium (RPE) damaged by sodium iodate. RPE was damaged by intravenous administration of sodium iodate, 10mg per kg body weight, in rats. This dose of the agent damaged RPE weakly. Twenty-four hours after the administration of sodium iodate, polystyrene particles were injected into the subretinal space trans-sclerally. Rats were sacrificed at 6 hours to 4 days after injection of particles. Twenty four hours after injection of sodium iodate, RPE were weakly damaged. The cell organelles were swollen and ruptured, but cell structures were not destroyed. Then particles were injected into the subretinal space, RPE did not phagocytize the particles until 24 hours after the injection of particles. After 48 hours, RPE showed proliferation. After 4 days, RPE formed thick multilayers in the subretinal space and transformed to spindle shapes, and RPE underwent metaplasia to fibroblast-like cells. However proliferation of RPE was not marked. RPE cells weakly damaged by sodium iodate showed delay in phagocytosis of the particles and decrease in proliferation and metaplasia to fibroblast-like cells.

Animals↗

PubMed1989

[Pathologic response of the regenerated retinal pigment epithelium (RPE)--affected by sodium iodate (NaIO3)].

Phagocytosis, proliferation and metaplasia to fibroblast-like cells in the regenerated retinal pigment epithelial cell (RPE) were examined after damage caused by administration of sodium iodate. The solution of sodium iodate (40 mg/kg) was given in a single intravenous injection in rats. Three days after injection, RPE showed marked necrotic damage, but in 2 weeks flat regenerated RPE with short microvilli and no basal infolding were seen on Bruch's membrane. Polystyrene particles were then injected into the subretinal space. The rats were sacrificed 6 hours to 4 days after injection of the particles. The regenerated RPE showed phagocytosis within 6 hours. After 48 hours, they showed multilayer proliferation. After 4 days RPE transformed to spindle-shaped fibroblast-like cells. However proliferation and metaplasia of RPE markedly decreased. The results showed significant decrease in the function of regenerated RPE-cells as a result of their damage.

Animals↗

PubMed1988

Demonstration of pancreatic secretory trypsin inhibitor in serum-free culture medium conditioned by the human pancreatic carcinoma cell line CAPAN-1.

Serum-free culture medium conditioned by an established human pancreatic adenocarcinoma cell line, CAPAN-1, contains copious amounts of immunoreactivity due to pancreatic secretory trypsin inhibitor (PSTI) as demonstrated by radioimmunoassay. The immunoreactive substance was purified from the conditioned medium to apparent homogeneity by trypsin affinity and gel filtration chromatography with an overall recovery of 40%, and its primary structure was determined by Edman degradation. The immunoreactive substance is a peptide of 56 amino acid residues with a calculated molecular weight of 6,241. Its amino acid composition, primary structure, and inhibitory effect against trypsin are indistinguishable from those of human pancreatic juice PSTI, indicating that this substance is PSTI itself. This is the first direct demonstration that tumor cells secrete PSTI in vitro. When CAPAN-1 was inoculated into a nude mouse, it produced a tumor and the tumor synthesized human PSTI in vivo, as demonstrated by the fact that the tumor extract contained 99.0 +/- 26.2 ng of human PSTI/mg of protein, while PSTI was not detected in extracts from other tissues examined. Furthermore, high levels of human PSTI (14.3 +/- 2.6 ng/ml) were detected in the serum of tumor-bearing mice but not in that of nontumor-bearing mice, suggesting that PSTI secreted from the tumor appears in the blood circulation. Taken together, these results strongly support the view that the serum levels of PSTI are elevated in cancer-bearing patients due to secretion of this peptide from tumor cells per se.

Adenocarcinoma↗

PubMed1988

In vitro and in vivo studies on antithrombogenicity of poly(propylene oxide) segmented nylon 610 in relation to its crystalline-amorphous microstructure.

In vitro and in vivo antithrombogenicity of poly(propylene oxide) segmented nylon 610 was investigated. For the in vitro simulation of thrombosis on copolymer surfaces, a modified microsphere column method evaluated the thrombosis time of the copolymer column. For the in vivo evaluation of the antithrombogenicity of copolymer surfaces, small diameter tubing, precoated with copolymer, was implanted in rabbits as an arteriovenous shunt to determine the time of patency for the copolymer tubing. In both the in vitro and in vivo tests, the copolymer having a particular size and distribution of crystalline and amorphous microphases on its surface exhibited excellent antithrombogenicity; the copolymer with a long period of approximately 12 nm and a crystallite thickness of 6.5 nm suppressed the activation process of adhering platelets to show thromboresistant property. This paper emphasizes the importance of controlling the crystalline-amorphous microstructure for the antithrombogenicity of polymer surfaces with a semicrystalline microstructure.

Animals↗

PubMed1988

Lindane but not deltamethrin blocks a component of GABA-activated chloride channels.

Effects of deltamethrin, a pyrethroid insecticide, and lindane, the gamma isomer of hexachlorocyclohexane, on the gamma-aminobutyric acid (GABA)-activated ion channels were studied using cultured neurons isolated from the newborn rat dorsal root ganglia. The neuron was voltage clamped using the whole cell patch clamp technique. Two components of inward chloride currents were generated in response to bath application of GABA. One of the components was selectively blocked by 1 x 10(-5)M lindane in a stereospecific manner, but neither component was affected by 1 x 10(-5)M deltamethrin, which drastically prolonged the voltage-activated sodium channel current. Thus, the action of lindane to stimulate the nervous system is partly because of an interaction with the GABA receptor-channel complex. The target site of deltamethrin is not the GABA receptor-channel complex but the sodium channel. The results suggest a multiplicity of the GABAA receptor-chloride channel complex.

Animals↗

PubMed1988