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Biomedical subjects

T Hatta

Publications and source records attributed to T Hatta.

179 records · Page 10Linked to original sources
PubMed1976

Asynchrony of lateral onset as a factor in difference in visual field.

An experiment in matching judgments was designed to examine a role of perceptual process in apparent asymmetry. Recognition of Hirakana letters (Japanese letters) was required. The experimental condition in which stimuli were presented to the left visual field first and to the right visual field second produced more errors for all stimulus intervals (0 to 60 msec.) than experimental conditions where stimuli were presented to the right visual field first and to the left one second. Especially, superiority of the latter condition was marked with the longest stimulus interval employed. These results indicate superiority of the left hemisphere function for recognizing Hirakana letters and suggest that not only memory but also perceptual process contributes to this laterality effect.

Brain↗
PubMed1976

Lateral onset asynchrony in left-handers.

Study of matching judgment was designed to demonstrate an effect of lateral onset asynchrony in left-handed subjects, 7 males and 8 females. Japanese Hirakana letters or random forms were presented to one visual field first and to the other visual field second. 15 left-handers were requested to judge whether the successively presented stimuli were "same" or "different." The results showed that for both types of stimuli there are no differences in accuracy of matching judgement whether the standard stimulus was presented to the right visual field first or to the left. These results indicate that the left-handed subjects may have a tendency toward hemispheric equi-potentiality for recognition of both verbal and non-verbal materials.

Discrimination, Psychological↗
PubMed1976

[Functional hemispheric asymmetries in perception of digit and line orientation orientation (author's transl)].

In Exp. I, right-handed Ss made the "same" or "diffeeent" judgement to paired digits serially presented to the right and left visual field, and exhibited erroneous judgements in the left visual field lead condition. These results suggest the left hemisphere superiority. In Exp. II, the Ss were requested to make the "same" or "different" judgment and to press a key as fast as possible to the paired line orientation. The right visual field lead condition product more errors than the left visual field lead condition. This suggests the right hemisphere superiority. But no difference appeared between both conditions in the reaction time. The opposite hemispheric superiority, found in perceiving verbal and non-verbal materials in the 2 experiments, would be attributed to the basic difference in "perceptual" process.

Dominance, Cerebral↗
PubMed1975

[Functional hemispheric asymmetry in perception of random forms (author's transl)].

2 experiments were conducted in which Ss made the "same-different" judgement with respect to a pair of random forms which were serially presented to the right and the left VF tachistoscopically. In Exp. I, the stimulus materials were random form painted solidly, and in Exp. II they were contour forms. The major results of both experiments were essentially the same. The results indicated that right VF-lead condition produced more errors than the left VF-lead condition, and that the high complexity form group produced more errors than the low complexity form group. The tendency of left VF-lead superiority was more pronounced when the interval between the 2 stimuli was longer. These results suggest the possibility of the right hemisphere's superior function concerning the perception of random forms.

Adult↗
PubMedDate not supplied

Effects of low-dose phenytoin administered to newborn mice on developing cerebellum.

To examine correlations between dose levels of phenytoin (PHT) and neurotoxic effects on cerebellar development, we administered 10, 17.5, 25, and 35 mg/kg PHT suspended in sesame oil orally to newborn Jcl:ICR mice once a day during postnatal days 2-4 and determined plasma PHT concentrations during the administration period. Mortality rates were 12.5% and 35.2% in males and 15.3% and 33.3% in females for the 25 and 35 mg/kg PHT-treated groups during the PHT treatment, respectively. In the 25 and 35 mg/kg PHT-treated groups, total brain weight, the size of the cerebellum, and cerebellar weight were significantly reduced on postnatal day 21. However, in the 10 and 17.5 mg/kg PHT-treated groups, total brain weight and the size and weight of the cerebellum did not differ from those of the control group. Histologically, the number of pyknotic cells in the external granular layer (EGL) in the 25 and 35 mg/kg PHT-treated groups was increased on postnatal day 5, and the EGL was thicker than in the control group on postnatal day 14. Some of the Purkinje cells in the 35 mg/kg PHT-treated group showed degeneration. Plasma PHT levels were 10.7 +/- 2.2 and 24.6 +/- 2.6 micrograms/ml in the 25 and 35 mg/kg PHT groups on the third day of PHT treatment, respectively. In the 25 mg/kg PHT group, plasma PHT level was found to be in the therapeutic range for humans, 10-20 micrograms/ml. Accordingly, during pregnancy, epileptic women should be carefully given PHT at the lowest effective dose while plasma PHT levels are monitored properly. These findings emphasize the importance of pharmacokinetics in evaluating of phenytoin-induced developmental neurotoxicity.

Animals↗
PubMedDate not supplied

Neurotoxic effects of phenytoin on postnatal mouse brain development following neonatal administration.

Phenytoin (PHT) is a commonly used anticonvulsant drug. It has been reported that children exposed prenatally to PHT have brain malformations and psychomotor dysfunction. The neonatal development of the central nervous system (CNS) in mice corresponds to the last trimester in humans. To examine the neurotoxic effects of PHT on postnatal brain development, we administered PHT at doses of 10, 17.5, 25, or 35 mg/kg to newborn mice once a day during postnatal days (PD) 2-4. These dose levels result in plasma levels corresponding to the therapeutic ranges in humans. We measured the weight of total brain, cerebrum, cerebellum, and brain stem on PD 5 through 21, and examined early motor functions including head elevation, elevation of pelvis, pivoting, crawling, and righting reflex . Total brain weight, cerebral weight, and cerebellar weight in the group treated with 25 or 35 mg/kg were significantly reduced compared to controls from PD 5 to 21. Mice treated with PHT at 25 or 35 mg/kg showed decreased locomotor abilities and righting reflex on PD 5. In all phenytoin treatment groups, phenytoin levels in the brain were higher than those in the plasma on the third day of PHT treatment. We thus observed neurotoxic effects of PHT on postnatal brain development in mice. Our present data may provide useful implications for the management of PHT-induced developmental neurotoxicity and evaluation of psychomotor development in children exposed to PHT during the late fetal period.

Aging↗
PubMedDate not supplied

Inhibition of influenza virus replication by phosphorothioate and liposomally endocapsulated oligonucleotides.

We have demonstrated that antisense phosphorothioate oligonucleotides (S-ODNs) inhibit influenza virus A replication in MDCK cells. Phosphorothioate and liposomally encapsulated oligonucleotides with two target sites (PB1 and PB2) were synthesized and tested for virus-induced cytopathogenicity effects by a MTT assay using MDCK cells. The liposomally encapsulated S-ODNs complementary to the sites of the PB2-AUG initiation codon showed highly inhibitory effects. On the other hand, the inhibitory effect of the liposomally encapsulated S-ODNs targeted to PB1 was considerably decreased in comparison with the PB2 target sites. The liposomally encapsulated oligonucleotides exhibited higher inhibitory activity than the free oligonucleotides. The activities of the modified oligonucleotides are effectively enhanced by using the liposomal carrier.

Antiviral Agents↗
PubMedDate not supplied

In vitro and in vivo anti-influenza A virus activity of antisense oligonucleotides.

We have demonstrated that antisense phosphorothioate oligonucleotides (S-ODNs) inhibit influenza virus A replication in MDCK cells. The liposomally encapsulated and the free antisense phosphorothioate oligonucleotides with four target sites (PB1, PB2, PA, and NP) were tested for their abilities to inhibit virus-induced cytopathogenic effects by a MTT assay using MDCK cells. The liposomally encapsulated S-ODN complementary to the sites of the PB2-AUG initiation codon showed highly inhibitory effects. Therefore, the antiviral effects of S-ODN-PB2-AUG and PA-AUG were examined in a mouse model of influenza virus A infection. PB2-AUG oligomer treated i.v. significantly prolonged the mean survival time in day (MDS) and increased the survival rates with does dependent manner.

Animals↗