PubMed Health⌕ Search

Biomedical subjects

N Kawabata

Publications and source records attributed to N Kawabata.

At least 37 records · Page 2Linked to original sources
PubMed1990

Structural information processing in peripheral vision.

Structural visual information processing was investigated in peripheral vision. Perceptual completion, as observed at the blind spot, occurred across a vertical blank stripe in a test pattern, presented in the peripheral visual field. That is, a shape, organized by structural processing, was perceived under critical visual conditions when it was presented in peripheral vision. The results indicate that structural processing, as indicated by perceptual completion, occurs in the peripheral visual information handling process. The results suggest that structural processing of shape information is built into the peripheral visual system and reduces the information load on the higher visual processes under conditions in which visual information is not adequate.

Adult↗
PubMed1990

Effect of L-cysteine on distribution volume of 1-(tetrahydro-2-furanyl)-5-fluorouracil.

Higher plasma concentrations of 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) were obtained after administration of FT (100 mg/kg, i.v.) combined with L-cysteine (CySH, 500 mg/kg, p.o.). The volume of distribution (Vd) and body fluid volumes significantly decreased. These results suggest that the increase of the plasma concentrations of FT can be attributed to the decrease of the Vd of FT, which is considered to be based on the decrease of body fluid volumes by the combined administration of CySH.

Animals↗
PubMed1990

Prevalence of spotted fever group rickettsia antibody in Apodemus speciosus captured in an endemic focus in Miyazaki Prefecture, Japan.

Fourteen of Apodemus speciosus (large Japanese field mouse) were captured near the place where one of the patients with spotted fever group rickettsiosis had been infected, in Takaoka town, Miyazaki Prefecture. In the town, four human cases were reported. All of the mice had antibodies against Rickettsia japonica and R. montana. The incidence of the antibody was significantly higher in Apodemus mice in the area than in those from nonendemic area.

Animals↗
PubMed1989

[Antigenic types of Rickettsia tsutsugamushi isolated from patients with tsutsugamushi fever and their distribution in Miyazaki Prefecture].

Rickettsia tsutsugamushi (Rt) isolated from patients with tsutsugamushi fever were examined for their antigenicity. This was done by indirect immunofluorescence (IIF) with guinea pig antisera against three standard strains (Karp, Kato and Gilliam) and two local strains (Kawasaki and Kuroki) isolated in 1981, and with mouse monoclonal antibodies against the three standard strains. In the meantime, antibodies in sera from 317 out of 442 patients registered during 1985 to 1988 were titrated by IIF with those five Rt strains. 1) Local isolates, Kawasaki and Kuroki strains, reacted most effectively with the homologous antiserum, respectively, showing four fold lower IIF titers against the heterologous antisera. 2) Kawasaki strain reacted with none of the monoclonal antibodies, whereas Kuroki strain showed a slight reaction with anti-Karp and anti-Kato, but not anti-Gilliam, monoclonal antibodies. 3) Seventeen out of 27 strains isolated in 1985 resembled the Kawasaki strain in their reaction patterns with the antisera and monoclonal antibodies, and the other 10 strains showed reactivity similar to the Kuroki strain. 4) Sera of 233 (74%) out of 317 patients showed the highest antibody titers against the Kawasaki strain and 69 (22%) of 317 against the Kuroki strain. It is thus evident that Kawasaki and Kuroki strains are antigenically different from the standard strains, and Kawasaki and Kuroki strains also differ from each other. It is suggested that two antigenic types (Kawasaki and Kuroki) of Rt were distributed in Miyazaki Prefecture, Rt of the Kawasaki type slightly dominates Rt of the Kuroki type, and recent tsutsugamushi fever has been caused by either one or the other type of Rt.

Antigens, Bacterial↗
PubMed1989

Silent myocardial ischemia during Holter monitoring in ischemic heart disease.

The purpose of this study was to investigate the frequency and characteristics of silent myocardial ischemia in patients with proven ischemic heart disease using ambulatory ECG monitoring, and to clarify possible mechanisms for the absence of symptoms during these attacks. A total of 182 patients, including 78 patients with stable effort angina (EA), 12 with unstable angina (UA), and 92 with prior myocardial infarction (MI), were examined. During daily activities, 43% and 56% of all transient ST-segment depression observed was asymptomatic in patients with EA and MI, respectively. In addition, 74% of all ischemic episodes were asymptomatic in patients with UA. In patients with EA, 35% exhibited both symptomatic and asymptomatic attacks, and the duration and magnitude of ST-segment depression were greater for symptomatic attacks than for asymptomatic attacks. On the other hand, in patients with MI, 55% had only asymptomatic attacks. When asymptomatic episodes in patients who had only asymptomatic attacks were compared with symptomatic episodes in patients who had only symptomatic attacks, asymptomatic episodes tended to be associated with a greater magnitude of ST depression. They were also significantly longer in duration than the symptomatic episodes. All patients with UA had both symptomatic and asymptomatic episodes, and the magnitude and duration were significantly greater during the former. These results lead us to conclude that: (1) silent myocardial ischemia is observed frequently in patients with EA and MI during daily activities. In particular, patients with MI tend to have more severe silent ischemia. (2) In patients with EA and UA, the severity of ischemia is a fundamental factor in determining the presence or absence of pain during an ischemic attack.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1989

[Effects of flutropium bromide, a new antiasthma drug, with repeated administration on bronchomotor response and hepatic drug metabolizing enzymes].

Effects of flutropium bromide, a new antiasthma drug possessing the quarternary ammonium structure of atropine derivatives, were investigated on the bronchodilatory activity with repeated inhalations in guinea pigs and on the hepatic drug metabolizing enzyme activities with repeated i.v. administration in rats. Single inhalation of flutropium bromide (0.03%) inhibited the ACh-induced bronchoconstriction without changing the fall in blood pressure induced by ACh. Flutropium bromide (0.03%) was inhaled for 5 min a day by placing the animal in an inhalation box, successively during periods of 14 and 28 days. The bronchodilatory effect of flutropium bromide after 14- or 28-day repeated inhalations was almost the same potency as that after single inhalation. Twenty-eight-day repeated inhalations did not change the body weight curve in guinea pigs; and in addition, 14-day repeated i.v. administration did not change the hepatic drug metabolizing enzyme activities in rats. From the above results, it is indicated that flutropium bromide causes neither reduction in response nor cumulative effect after repeated inhalations, and that the agent maintains the bronchodilatory effect without change in the hepatic drug metabolizing enzyme activities.

Acetylcholine↗
PubMed1988

Antibacterial activity of soluble pyridinium-type polymers.

Cross-linked poly(N-benzyl-4-vinylpyridinium halide) (designated insoluble BVP) was previously reported to capture bacterial cells alive by contact with them. The corresponding linear polymer poly(N-benzyl-4-vinylpyridinium salt) (designated soluble BVP) was found to exhibit antibacterial activity. This soluble pyridinium-type polymer showed strong antibacterial activity against gram-positive bacteria, whereas it was less active against gram-negative bacteria. The antibacterial activity of this cationic, polymeric disinfectant was considerably greater than that of the corresponding monomeric compound and was approximately equal to that of conventional disinfectants such as benzalkonium chloride and chlorohexidine.

Bacteria↗
PubMed1987

Evidence for infection caused by spotted fever group Rickettsia in Kyushu, Japan.

Of 50 cases that gave negative immunofluorescence reaction with Rickettsia tsutsugamushi among patients with suspected tsutsugamushi disease encountered in Miyazaki Prefecture during the last four years, three showed a significant rise in the antibody titer to Rickettsia montana, a species of spotted fever group. This paper reports evidence for the occurrence of the rickettsial infection of the spotted fever group in Kyushu, Japan.

Adult↗
PubMed1986

Attention and depth perception.

The Necker cube is a line drawing with two possible solutions in depth perception. The process of interpreting a two-dimensional line drawing as a three-dimensional object was investigated using the Necker cube. Attention was directed to a local feature of a briefly presented cube, ie an angle at a vertex. The attended angle was perceived as a front part of the cube and other parts were interpreted so as to match this interpretation. Results show that the local feature to which attention was directed was interpreted first and then global features and other local features were interpreted so as to agree with the local feature interpreted initially. This suggests that the three-dimensional interpretation of the line drawing was made sequentially from the local feature to global structures.

Attention↗
PubMed1986

Immunological properties of Rickettsia tsutsugamushi, Kawasaki strain, isolated from a patient in Kyushu.

Nine isolates of Rickettsia tsutsugamushi were obtained from patients with Tsutsugamushi disease (scrub typhus) in Miyazaki Prefecture in Kyushu. Immunological analyses of these patients' sera and the isolates were performed by indirect immunofluorescence, indirect immunoperoxidase or immunoblotting techniques. In the analysis of reactions of the patients' sera with the prototype strains Gilliam, Karp, and Kato and with the isolates, sera from two patients, including Kawasaki, showed similar profiles and cross-reaction with the two isolates recovered from the corresponding patients, but reacted only weakly with the prototype strains. With guinea pig polyclonal antibodies against the isolate and prototype strains, Kawasaki strain showed some degree of cross-reaction with Gilliam strain but not with either Karp or Kato strain, nor with Shimokoshi strain which is known to be different antigenically from the prototype strains. Additionally, strain-specific murine monoclonal antibodies against Gilliam, Karp, and Kato strains did not react at all with Kawasaki strain. These results suggest that the Kawasaki strain may be different antigenically from the prototype strains and Shimokoshi strain. The finding two strains of the same antigenic type (Kawasaki) among only nine isolates suggests the presence of Kawasaki-type rickettsiae in Miyazaki Prefecture. Shimokoshi strain also did not react with these strain-specific monoclonal antibodies, suggesting that strains of R. tsutsugamushi antigenically distinct from the prototype strains, such as Kawasaki and Shimokoshi strains, may easily be recognized by their nonreactivity with these monoclonal antibodies.

Animals↗
PubMed1985

Neural interactions of two moving patterns in the direction and orientation domain in the complex cells of cat's visual cortex.

An examination was made of the responses of complex cells in cat's striate cortex to a textured (nonoriented) stimulus moving in the preferred direction, superimposed upon either a textured or a grating stimulus (oriented) that was moved in different directions. The cell discharges elicited by the textured stimulus moving in the preferred direction were reduced by the textured stimulus moving in nonpreferred directions, and increased when moved in the preferred direction. A grating moving in nonpreferred directions showed similar inhibitory effects on the responses to a textured stimulus moving in the preferred direction. Neural processing for directional movement is, therefore, affected by other neural processing for directional movement, and still more by that for orientation.

Animals↗
PubMed1983

Simultaneous determination of tegafur and 5-fluorouracil in serum by GLC using nitrogen-sensitive detection.

A sensitive assay of both tegafur (I) and 5-fluorouracil (5-FU) using GLC with a nitrogen-phosphorus-sensitive detector is described. The drugs were extracted from rabbit serum with ethyl acetate and methylated with diazomethane. Linearity was obtained over the concentration ranges of 3.13-200 micrograms/ml for I and 0.0313-2 micrograms/ml and 10-50 ng/ml for 5-FU. The detection limits of I and 5-FU in serum were 50 and 8 ng/ml, respectively. The serum concentrations of the drugs determined by the present method closely agreed with those obtained by spectrophotometry for I and microbial assay for 5-FU.

Animals↗
PubMed1983

Neural interactions of two slits in the orientation domain in the visual cortical units of the cat.

The responses of the cat's visual cortical cells to an optimally oriented (O-) and an inclined (theta-) slit have been studied. Cell's responses to the simultaneous presentation, in simple cells, are similar to those to theta-slit alone, but in complex cells, are remarkably decreased at orientation difference of about 45 degrees. In the sequential presentation, the effects of preceding theta-slit on the responses to the following O-slit decrease as the orientation difference increases. This suggests that neural interactions of simultaneous and sequential presentation of two slits are caused by different mechanisms.

Animals↗
PubMed1983

Global interactions in perceptual completion at the blind spot.

Nonlinearity and asymmetrical property in the filling-in process at the blind spot are investigated. Perceptual completion of a pattern with a gap is deteriorated, i.e. gap information inhibits completion across the gap. Filled-in patterns, observed from complementary patterns, are not the same in complementary sense. These suggest that perceptual completion cannot simply be predicted from a superimposition of completions, obtained from local stimulus conditions, and seems to be mediated by global processes.

Humans↗
PubMed1983

Removal of bacteria from water by adhesion to cross-linked poly(vinylpyridinium halide).

Cross-linked poly(vinylpyridinium halide) was found to have a novel and remarkable ability to remove bacteria from water. For example, when 10 g (wet weight) of cross-linked poly(N-benzyl-4-vinylpyridinium bromide) was contacted with 20 ml of suspensions of Escherichia coli (9.7 X 10(4) to 9.7 X 10(7)/ml), Salmonella typhimurium (8.0 X 10(6) to 1.1 X 10(7)/ml), Streptococcus faecalis (5.0 X 10(7)/ml), Staphylococcus aureus (8.1 X 10(7)/ml), and Pseudomonas aeruginosa (3.2 X 10(5)/ml) under stirring in sterilized physiological saline at 37 degrees C, 99% of the viable cells of these bacteria were removed in 2 to 6 h. When suspensions of these bacteria (10(5) to 10(8) cells per ml) were passed through a column (20 mm by 100 cm) of cross-linked poly(N-benzyl-4-vinylpyridinium bromide) at 37 degrees C with a flow rate of 0.8 to 1.4 bed volumes per h, 97 to 100% of the viable cells were eliminated from the suspensions during the treatment. Mechanistic studies demonstrated that cross-linked poly(vinylpyridinium halide) irreversibly captured these bacteria alive during the treatment. That is, total organic carbon was removed during the treatment, and the bacteria which adhered to the resin proliferated on the bacterial medium. The adhesion capacity was estimated to be 10(10) cells per g (dry weight). Total organic carbon was also removed even when the bacteria were killed by heat treatment before the column studies.

Adhesiveness↗
PubMed1983

Studies to increase the antitumor activity of 1-(tetrahydro-2-furanyl)-5-fluorouracil and its metabolic aspects by combined administration with L-cysteine.

The plasma and liver concentrations of both 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) and 5-fluorouracil (5-FU), an active metabolite of FT, increased very markedly after administration of FT (500 mg/kg, p.o.) combined with L-cysteine (L-CYS, 500 mg/kg, i.p. or p.o.) when compared to FT alone in rats. On the other hand, the oral acute toxicity of FT was also enhanced with the combined administration of FT and L-CYS. There was no difference in the in situ absorption rate of FT from the small intestine between rats treated with L-CYS (500 mg/kg, i.v.) and vehicle-treated controls. The inhibition of the disappearance of FT and the increase of the formation of 5-FU was observed in vitro after incubation of FT with liver microsomes from rats treated with L-CYS (500 mg/kg, p.o.) when compared to vehicle-treated controls. The presence of L-CYS significantly inhibited the in vitro degradation of 5-FU by non-treated rat liver homogenate. In the drug metabolizing enzyme activity of rat liver microsomes, aniline p-hydroxylase activity was inhibited, but aminopyrine N-demethylase activity was conversely activated by the combined administration of FT and L-CYS, but not by FT alone; furthermore, no change of cytochrome P-450 content was observed. In sarcoma 180 bearing mice, the oral antitumor activity of FT in combination with L-CYS (500 mg/kg, i.p. or p.o.) was about 1.1-2.0 times higher than that of FT alone. It was concluded from these findings that the drug metabolizing enzymes in liver involved in the conversion of FT into an active metabolite, 5-FU, are influenced by the combined administration of FT and L-CYS to give an increased organ level of 5-FU; and this resulted in the enhancement of the antitumor activity of FT.

Absorption↗