Biomedical subjects

T Asami

Publications and source records attributed to T Asami.

At least 19 recordsLinked to original sources

PubMed1992

Effects of repeated MK-801 on ambulation in mice and in sensitization following methamphetamine.

The noncompetitive NMDA receptor antagonist MK-801, (+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]-cyclohepten-5,10-imine , increased ambulatory activity in the mouse at doses over 0.1 mg/kg (IP). The effect was enhanced when 0.3 mg/kg MK-801 was repeatedly administered at intervals of 3-4 days. In contrast, a reduction of the effect was induced with repeated doses of 0.1 and 1 mg/kg. The mice that had repeatedly experienced 1 mg/kg MK-801 exhibited a decrease in the sensitivity to methamphetamine (2 mg/kg SC). In addition, the repeated co-administration of 1 mg/kg MK-801 with methamphetamine induced a decrease in the sensitivity to methamphetamine. No modification of methamphetamine sensitivity was elicited by 0.1 and 0.3 mg/kg MK-801 in both the single and co-administration schedules. On the other hand, established sensitization to methamphetamine was hardly affected by repeated treatment with 0.1-1 mg/kg MK-801. These results indicate that the mechanism of the inhibitory action of MK-801 on the development of methamphetamine sensitization is different from that of dopamine D2 antagonists, which may act to decrease the effective unit dose of methamphetamine and reduce ambulation-increasing effect of methamphetamine.

Animals↗

PubMed1992

Circadian variation in R-THBP-induced enhancement of the ambulation-increasing effect of methamphetamine on mice.

6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP), a co-factor for tyrosine hydroxylase and tryptophan hydroxylase, induces the enhancement of ambulation-increasing effect of methamphetamine on mice. In this study, we investigated the circadian variation in the interaction between R-THBP and methamphetamine by changing the time-of-day of both methamphetamine administration and pretreatment with R-THBP. The mouse's ambulatory activity was measured by a tilting-type activity cage for 4 hr. In the daytime, but not in the nighttime, the ambulation-increasing effect of methamphetamine (1 and 2 mg/kg, s.c.) was significantly enhanced by the pretreatment with R-THBP (100 mg/kg, s.c., 2 or 6 hr before). These data indicate the possibility that peripherally administered R-THBP increases the biosynthesis of catecholamine especially in the daytime.

Analysis of Variance↗

PubMed1992

Heat treatment of Japanese lacquerware renders it hypoallergenic.

Japanese lacquer is made from the sap of the Japanese lacquer tree (Toxicodendron vernicifluum), a member of the Anacardiacae plant family. Objects painted with this material are described collectively as lacquerware. Both fresh lacquer and lacquerware may evoke allergic contact reactions ascribable to the urushiols contained therein. In this study, we have examined the effects of heating on the ability of lacquerware to elicit an allergic contact reaction. Lacquer films prepared with and without heat treatment were tested on urushiol-sensitive subjects. Patch test reactions were strongest to untreated film and decreased with increasing level of heat treatment. Assays for free urushiol in the lacquer films demonstrated that free urushiol content decreased with increasing heat treatment and that urushiols with saturated and monounsaturated alk(en)yl chains predominated.

Adult↗

PubMed1992

Genetic relatedness of Bradyrhizobium japonicum field isolates as revealed by repeated sequences and various other characteristics.

Forty-nine isolates of Bradyrhizobium japonicum indigenous to a field where soybeans were grown for 45 years without inoculation were characterized by using four DNA hybridization probes from B. japonicum. nifDK-specific hybridization clearly divided the isolates into two divergent groups. Diversity in repeated-sequence (RS)-specific hybridization was observed; 44 isolates derived from 41 nodules were divided into 33 different RS fingerprint groups. Cluster analysis showed that the RS fingerprints were correlated with the nif and hup genotypes. We found multiple bands of RS-specific hybridization for two isolates that differed from the patterns of the other isolates. These results suggest that RS fingerprinting is a valuable tool for evaluating the genetic structure of indigenous B. japonicum populations.

Bacterial Typing Techniques↗

PubMed1992

Glomerular deposition of alpha 2-macroglobulin in a child with steroid refractory nephrotic syndrome.

A four-year-old male with steroid refractory nephrotic syndrome was found to have diffuse deposition of alpha 2-macroglobulin (alpha 2M) in the glomeruli which showed diffuse mesangial proliferation and partial hyalinization by light microscopy. Camostat mesylate, a commercially available synthetic proteinase inhibitor, led to biochemical and clinical improvement. Twenty-two patients with 7 biopsy-proven renal diseases did not have any deposition of alpha 2M in their kidney tissue. Though the pathogenetic mechanism is unknown, this is probably the first report of the deposition of alpha 2M in renal tissue.

Child, Preschool↗

PubMed1992

Characteristics of the ambulation-increasing effect of the noncompetitive NMDA antagonist MK-801 in mice: assessment by the coadministration with central-acting drugs.

Characteristics of the ambulation-increasing effect of MK-801, a non-competitive NMDA antagonist, were assessed through the coadministration of MK-801 with various central-acting drugs in mice. The MK-801 (0.3 mg/kg, i.p.)-induced ambulation-increment with a slight ataxia was maximum at around 50 min, and ambulation returned to the control level at about 3 hr after the administration. At 1 mg/kg, the mouse's activity transiently increased, followed by a decrease due to a marked ataxia, which was due to neither stereotypy nor convulsion, for 20-50 min, and then increased again; the ambulation-increment continued even at 4 hr after the administration. Coadministration of MK-801 (0.3 mg/kg, i.p.) with either methamphetamine (2 mg/kg, s.c.), cocaine (20 mg/kg, s.c.), GBR-12909 (10 mg/kg, i.p.), scopolamine (0.5 mg/kg, s.c.), caffeine (10 mg/kg, s.c.) or morphine (10 mg/kg, s.c.) produced a significant enhancement of the effect. However, 0.1 mg/kg of MK-801 had no effect on the interaction with these drugs. On the other hand, the ambulation-increasing effect of MK-801 (0.3 mg/kg) was significantly reduced by haloperidol (0.3 and 0.1 mg/kg, s.c.), ceruletide (0.01 and 0.1 mg/kg, i.p.), reserpine (0.05 and 2 mg/kg, s.c., pretreatment 4 hr before) and nimodipine (1 and 3 mg/kg, i.p.), but it was scarcely modified by alpha-methyl-p-tyrosine (100 and 200 mg/kg, i.p., pretreatment 24 hr and 4 hr before), imipramine (20 mg/kg, i.p.), 6R-L-erythro-5,6,7,8-tetrahydro-biopterin (100 mg/kg, i.p.), pilocarpine (1 and 4 mg/kg, s.c.), N6-(L-2-phenylisopropyl)-adenosine (0.03 and 0.1 mg/kg, s.c.) and naloxone (1 and 5 mg/kg, s.c.).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Fine structure of the dorsal epithelium of the tongue of the Japanese terrapin, Clemmys japonica (Cheloia, Emydinae).

As reptiles are situated phylogenetically between the amphibians and the mammals, they exhibit considerable variation in the structure of their tongues. The present study, one of a series of studies on reptile tongues, aims to demonstrate the three-dimensional structure of the dorsal lingual surface of a turtle, the Japanese terrapin Clemmys japonica, and to clarify the ultrastructural features of the lingual epithelial cells. In the study lingual papillae were observed by scanning electron microscopy to be widely distributed over the dorsal surface of the tongue. Irregularly shaped (conical, columnar or angular) papillae were located in the anterior and central areas, and ridge-like ones, in the latero-posterior area. Histological examination revealed that the connective tissue penetrated into the core of the papillae, and the epithelium was of a stratified squamous and/or cuboidal type. Under the transmission electron microscope, two types of cells were identified in the intermediate layer of the apical epithelium of the lingual papilla: one type was probably an immature mucous cell, whereas the other was elongated in a baso-apical direction, its cytoplasm containing fine granules. In the surface layer of the apical epithelium, typical mucous cells and cells containing numerous, fine, electron-lucent granules were recognized. Both types of cells possessed microvilli on their free-surfaces. In the lateral epithelium of the lingual papillae, the cytological features from the basal layer to the superficial intermediate layer were essentially the same as in the apical epithelium. However, in the surface layer, mucous cells were significantly larger in number than in the apical epithelium.

Animals↗

PubMed1992

Study on the relation between renal tubular disorders and glomerular dysfunction in the early phase of insulin-dependent diabetes mellitus in children.

To study the relations between renal tubular disorder and glomerular dysfunction in the early phase of insulin-dependent diabetes mellitus (IDDM), we performed concomitant measurements of urinary beta-D-N-acetyl glucosaminidase (NAG), beta 2-microglobulin (BMG), and microalbumin in 29 of pediatric patients with IDDM, 15 normal controls, and 83 patients with non-diabetic ketoacidosis. Urinary NAG levels were significantly elevated in the IDDM patients compared with controls. Urinary BMG levels were also elevated in IDDM, however, they were not as prominent as NAG levels. Although urinary microalbumin levels were elevated in the IDDM patients, statistical analysis did not show any significant difference between the IDDM patients and controls. Urinary NAG and BMG concentrations were also increased in patients with non-diabetic ketoacidosis, suggesting a toxic effect of ketone bodies to renal tubular cells. Statistically significant correlations were noted both between urinary NAG and microalbumin and between urinary BMG and microalbumin. These results suggest that, in early phase of IDDM, microalbuminuria is preceded by elevations in urinary NAG and BMG levels, and that keton bodies have deleterious effects on renal tubular cells.

Acetylglucosaminidase↗

PubMed1991

[A study of the determination of serum fucose concentrations].

We examined the biochemical properties of reaction products during the procedure for serum fucose determination (Dische & Shettles). The optical density at 396 nm (OD396) of the reaction products increased linearly with the increment of fucose concentrations, and was stable for at least 210-240 min at room temperature. The reaction products were destroyed with the addition of distilled water. Sephadex G-200 gel chromatography of the mixed serum samples revealed a single peak of fucose in the void volume fractions. Of interest was the presence of trace amounts of fucose detected in the low-molecular weight fractions less than 66,000, suggesting the presence of free fucose in the serum. Based on these observations, the method for serum fucose determination was modified so it was possible to use 100 microliters of the serum sample. The mean serum fucose concentration, measured by this modified method, was 561.0 +/- 191.1 mumol/l (9.1 +/- 3.1 mg/dl) in normal healthy children. In patients with idiopathic nephrotic syndrome, the values were significantly higher both at relapse and in remission than those in normal healthy children.

Chemical Fractionation↗

PubMed1990

Rhizobitoxine inhibition of hydrogenase synthesis in free-living Bradyrhizobium japonicum.

Rhizobitoxine produced by Bradyrhizobium species strongly prevented derepression of hydrogenase expression in free-living Bradyrhizobium japonicum, although the toxin had no effect on the activity of cells which had already synthesized hydrogenase protein. Dihydrorhizobitoxine, a structural analog of rhizobitoxine, proved to be a less potent inhibitor of hydrogenase derepression. Rhizobitoxine did not cause cell death at a concentration sufficient to eliminate hydrogenase expression. The large subunit of hydrogenase was not detectable with antibody after derepression in the presence of rhizobitoxine. The general pattern of proteins synthesized from 14C-labeled amino acids during derepression was not significantly different in the presence or absence of rhizobitoxine. These results indicated that rhizobitoxine inhibited hydrogenase synthesis in free-living B. japonicum. Cystathionine and methionine strongly prevented the inhibition of hydrogenase derepression by rhizobitoxine, suggesting that the inhibition involves the level of sulfur-containing amino acids in the cell.

Bacterial Proteins↗

PubMed1990

[Characteristics of antagonism between ceruletide and various central-acting drugs: investigation by means of ambulatory activity in mice].

Behavioral characteristics of ceruletide, a cholecystokinin-like decapeptide, were investigated by means of ambulatory activity in mice. Ceruletide at 100 and 300 micrograms/kg, i.p. slightly but significantly decreased the mouse's activity for 20 min. Therefore, 100 micrograms/kg of ceruletide was used in the experiment of combined administration with the central-acting drugs. Ceruletide reduced the increased activity which was produced by methamphetamine (2 mg/kg, s.c.), ephedrine (80 mg/kg, i.p.), methylphenidate (4 mg/kg, s.c.), cocaine (20 mg/kg, s.c.), mazindol (2.5 mg/kg, s.c.), apomorphine (0.5 mg/kg, s.c.), bromocriptine (8 mg/kg, i.p.), scopolamine (0.5 mg/kg, s.c.), caffeine (10 mg/kg, s.c.) and morphine (20 mg/kg, s.c.) with different potencies and durations. The mice that had experienced ceruletide at 3 micrograms/kg for 5 times at intervals of 3-4 days demonstrated a significant increase in the sensitivity to methamphetamine, although the same treatment with 10-300 micrograms/kg of ceruletide was without effect. On the other hand, when 3-300 micrograms/kg of ceruletide was combined with 2 mg/kg of methamphetamine, the development of reverse tolerance to the ambulation-increasing effect of methamphetamine was inhibited dependently on the doses of ceruletide. However, the reverse tolerance to methamphetamine once established was scarcely modified by ceruletide when it was administered afterwards.

Animals↗

PubMed1990

Behavioral study on mergocriptine (CBM36-733) by ambulatory activity in mice: repeated administration and interaction with methamphetamine.

Effects of repeated administration of mergocriptine (CBM36-733: CBM), a long-acting ergot derivative with an agonistic action on both dopamine D1 and D2 receptors, as well as interaction between CBM and methamphetamine (MAP: 2 mg/kg, s.c.), were investigated by ambulatory activity in mice. CBM at 4 mg/kg significantly suppressed the ambulatory activity, but significantly increased it at 16 mg/kg in the drug-naive mice. However, 4 and 8 mg/kg of CBM were effective for increasing the ambulatory activity when these doses were repeatedly administered for 9 times at intervals of 7 days. The same treatment with 16 mg/kg of CBM produced a reverse tolerance to the ambulation-increasing effect. The mice that had received CBM at 1 and 2 mg/kg, but not 4-16 mg/kg, demonstrated a significantly lower sensitivity to MAP than the saline-experienced mice. On the other hand, the repeated MAP administration induced not only a reverse tolerance to itself, but also a cross reverse tolerance to 8 and 16 mg/kg of CBM. Furthermore, the established reverse tolerance to MAP was scarcely attenuated by the repeated treatment with any doses of CBM, but rather enhanced by 8 and 16 mg/kg of CBM. The present results indicate that, although the dose-effect relations are partially different, the behavioral characteristics of CBM were almost identical with those of bromocriptine, another long-acting ergot derivative having antagonistic and agonistic actions on dopamine D1 and D2 receptors, respectively.

Animals↗

PubMed1990

Effects of ceruletide, administered singly and in combination with central-acting drugs, on discrete shuttle avoidance response in mice.

The single administration of ceruletide at 10-300 micrograms/kg, i.p., slightly but significantly decreased the response rate (frequency of shuttles) under a discrete avoidance task in mice. Over 10 micrograms/kg of ceruletide attenuated the increase in the response rate induced by methamphetamine (0.5 mg/kg, s.c.). However, ceruletide, at 1-300 micrograms/kg, did not significantly enhance the response- and/or avoidance-decreasing effects of chlorpromazine (1 mg/kg, s.c.), haloperidol (0.1 mg/kg, s.c.), pilocarpine (4 mg/kg, s.c.) and N6-(L-2-phenylisopropyl)-adenosine (0.1 mg/kg, s.c.), but rather tended to reduce the avoidance-decreasing effect of chlorpromazine and pilocarpine at 1-100 micrograms/kg.

Animals↗

PubMed1990

[Blood glutathione in idiopathic nephrotic syndrome of childhood].

We studied blood glutathione in children with idiopathic nephrotic syndrome (INS). Plasma glutathione concentrations were significantly (p less than 0.02) lower in INS patients at relapses (0.37 +/- 0.29 microgram/ml, n = 21) than those in controls (0.62 +/- 0.36 microgram/ml, n = 22). As compared with patients with chronic glomerulonephritis (316.4 +/- 128.3, n = 8), the INS patients had lower blood glutathione concentrations (208.3 +/- 46.1 micrograms/ml, n = 6), although the difference was not statistically significant (p less than 0.10). The glutathione, mixed in the solutions containing plasma proteins or bovine serum albumin, showed sequential reductions of the concentration with time. There was no significant difference between the blood glutathione concentrations in the rats given glutathione containing water for 7 days and in those given distilled water. An inverse correlation was noted between blood glutathione and plasma cholesterol levels in the rats. From these results it may be concluded that INS patients have a decreased blood glutathione level, although the cause is unknown.

Adolescent↗

PubMed1989

Zinc ion enhances the blocking potency of synthetic analogs of spider toxin (JSTX) on the glutamate receptor.

The effect of synthetic spider toxin analogs containing aza-crown in combination with zinc and copper was studied on the lobster neuromuscular synapse. The suppressive action of N4-type spider toxin analog (N4) on excitatory postsynaptic potentials (EPSPs) was markedly enhanced in the presence of 10(-5)-10(-4) M Zn2+. Cu2+ (10(-4) M) also had a potentiating effect on the suppression of EPSPs by N4 but to a lesser degree than Zn2+. While N6-type spider toxin analog (N6) suppressed EPSPs more effectively than N4, additional suppression was not pronounced in the presence of Zn2+ or Cu2+. The results suggest that chelatable divalent metal ions play an important role in the blocking mechanism of glutamate receptor by the spider toxin.

Action Potentials↗

PubMed1989

In vivo antitumor mechanism of natural human tumor necrosis factor involving a T cell-mediated immunological route.

We have investigated the in vivo antitumor mechanism of natural human tumor necrosis factor (n-TNF) isolated from a culture of human leukemic B cell line (BALL-1), especially its action as an immunomodulator, and found that the in vivo antitumor effect of n-TNF on Meth A sarcoma implanted in BALB/c mice pretreated with monoclonal antibody against T cell-specific surface antigen (Thy-1) was significantly diminished. Furthermore, when BALB/c mice were treated with T cell subset-specific monoclonal antibodies, anti-L3T4 or anti-Lyt-2.2, the antitumor effect of n-TNF on Meth A sarcoma was significantly reduced. Therefore, it was suggested that the in vivo antitumor mechanism of n-TNF might involve a T cell-mediated immunological route.

Animals↗

PubMed1989

Enhancement of ambulation-increasing effect of methamphetamine by peripherally-administered 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) in mice.

Behavioral effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP), a co-factor for tyrosine hydroxylase and tryptophan hydroxylase, were investigated by means of ambulatory activity in mice. Single administration of R-THBP (50 and 100 mg/kg, s.c.) showed no significant effect on the mouse's ambulatory activity for 5 hr. The ambulation-increasing effect of methamphetamine (2 mg/kg, s.c.) was dramatically enhanced and prolonged by the pretreatment with R-THBP (100 mg/kg, s.c.) 0, 2, 6, 12 and 24 hr before, but not 18 or 36 hr before, the methamphetamine administration. However, when combined administration of R-THBP (100 mg/kg, s.c., 2 hr before) with methamphetamine (2 mg/kg, s.c.) was repeated at intervals of 3-4 days, the enhancement by R-THBP of the methamphetamine effect was observed only in the 1st and 2nd administration, but not in the later administration. The pretreatment with R-THBP (100 mg/kg, s.c., 2 hr before) enhanced the ambulation-increasing effect of ephedrine (80 mg/kg, i.p.), but failed to modify those of cocaine (20 mg/kg, s.c.), mazindol (2.5 mg/kg, s.c.), bromocriptine (8 mg/kg, i.p.), morphine (20 mg/kg, s.c.) and scopolamine (0.5 mg/kg, s.c.). It is noteworthy that R-THBP differentially modifies the ambulation-increasing effect of the above-mentioned drugs.

Animals↗

PubMed1989

[Stereo architecture of the connective tissue papillae of lips and gingiva in newborn dogs].

The surface structure of the connective tissue papillae of lips and gingiva of newborn dogs 1 and 4 weeks after birth were observed by scanning electron microscopy. 1. Long term HCl treatment successfully removed the epithelial cell layer from the connective tissue over a large area of fixed material. 2. Connective tissue papillae of labial skin, labial mucosa and alveolar and gingival mucosa were exposed and it became clear that connective tissue papillae were highly developed at the labial margin and just beneath the gingival margin. 3. In the hair growing area of the labial skin, connective tissue papillae became smaller, and some ridge-like structures were found running vertically. 4. On the lining mucosa such as the labial and alveolar mucosa, the surface of the connective tissue papillae showed only ridge-like structures running vertically. 5. From the results of both light and electron microscopy, we concluded that there was a tendency for the area to have a thick epithelial cell layer which contained highly developed connective tissue papillae. This suggested that the blood vessels in the connective tissue papillae can carry nutrients closer to more epithelial cells penetrating deeply into the epithelium thickness.

Animals↗