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Biomedical subjects

S Ohdo

Publications and source records attributed to S Ohdo.

At least 73 records · Page 4Linked to original sources
PubMed1992

Chronopharmacological study of valproic acid in mice: comparison of oral and rectal administration.

This study was performed to investigate the influence of the dosing route on chronopharmacological aspect of valproic acid (VPA) in mice, comparing the oral and rectal route. ICR male mice, housed under a standardized light-dark cycle (lights on from 0700 to 1900), were orally or rectally administered 400 mg/kg VPA each at the following scheduled time: 0900, 1300, 1700, 2100, 0100 and 0500. VPA concentrations in plasma and brain were determined by gas-liquid chromatography. There was a circadian rhythm in the electroshock seizure (ES) threshold 30 min after oral VPA administration, with the highest value at the midlight (1300) and the lowest at the middark (0100) (p < 0.01). A significant circadian rhythm was also found in plasma and brain VPA concentrations 30 min after oral administration (p < 0.01). This finding is related to the rhythm in the ES threshold. In contrast to oral administration, no circadian rhythm in the ES threshold, plasma and brain VPA concentrations was observed after rectal administration. These values after rectal dosing showed higher levels in comparison to those after oral dosing. Thus, the rectal route for VPA might have merit to eliminate the time-dependent changes in VPA pharmacologic action and kinetics. The timing of drug administration is an important factor that must be carefully controlled in drug pharmacokinetic and pharmacodynamic studies and must be considered in planning dosing routes.

Administration, Oral↗
PubMed1992

[Infantile spasms in monozygotic twins with Smith-Lemli-Opitz syndrome type I].

Monozygotic twins with Smith-Lemli-Opitz syndrome who developed infantile spasms were presented. They were the result of the first full-term pregnancy of non-consanguineous parents. They had following abnormalities: marked growth and developmental retardation, congenital heart disease, light brown hair which is rare in Japanese, small dolichocephaly, hypertelorism, anteverted nostrils, micrognathia, hypospadias and shawl scrotum. The cranial MRI showed the delayed myelination of occipital lobe. As far as we could review published reports, we were unable to find other report on monozygotic twins having the Smith-Lemli-Opitz syndrome.

Abnormalities, Multiple↗
PubMed1992

Effects of social isolation on pentobarbital activity in mice: relationship to racemate levels and enantiomer levels in brain.

The effects of social isolation on hypnotic actions induced by pentobarbital (PB) were investigated pharmacokinetically in isolated and aggregated mice and rats. Animals were administered i.p. 50 mg/kg of sodium (+-)-PB, S(-)-PB or R(+)-PB. Experiments in mice indicated that the duration of sleep induced by sodium (+-)-PB was reduced in the isolated mice, while the onset of sleep or the (+-)-PB brain levels at the time of awakening did not differ significantly between isolated and aggregated mice. These results suggest that changes in pharmacokinetics of PB may underlie the difference in duration of sleep between isolated and aggregated mice. In additional experiments in mice, brain concentrations of (+-)-PB, S(-)-PB or R(+)-PB were determined at predetermined intervals after injection. These experiments demonstrated that the brain concentrations of (+-)-PB, as well as those of S(-)-PB, at each predetermined timepoint in mice sacrificed before awakening were significantly lower in the isolated mice. The brain R(+)-PB levels in the isolated mice were also significantly lower as compared with those in the aggregated mice at each timepoint after injection. Experiments in rats indicated that urinary 3'-hydroxypentobarbital (major metabolite) concentrations were higher in the isolated rats at 0 to 6 hr after injection, suggesting an increased rate of hepatic drug metabolism in the isolated rats. Take together, these findings suggest that an increased rate of metabolism of PB, especially that of the S(-)-enantiomer which is responsible for hypnotic action, in isolated rodents may be involved in the shorter duration of sleep time induced by sodium (+-)-PB.

Animals↗
PubMed1991

Distribution and purification of aspartate racemase in lactic acid bacteria.

The distribution of aspartate racemase (EC 5.1.1.13) in various kinds of bacteria demonstrated that the enzyme occurs in lactic acid bacteria, such as Streptococcus species and Lactobacillus species. The enzyme from Streptococcus thermophilus IAM10064 was more thermostable than that from Streptococcus lactis IAM1198 which contained the enzyme most abundantly among the lactic acid bacteria we examined here. We purified the enzyme about 3400-fold to homogeneity from cell-free extract of S. thermophilus, which is composed of two identical subunits with a molecular weight of 28,000 as a homodimer. The enzyme utilizes specifically aspartate as a substrate, but not alanine and glutamate. Maximal reaction velocity was observed at 37 degrees C and around pH 8.0. The sequence of the NH2-terminal amino acids of the enzyme was determined to be Met-Glu-Asn-Phe-Phe-Ser-Ile-Leu-Gly-XXX-Met-Gly-Thr-Met-Ala-Thr-Glu-Ser- Phe-.

Amino Acid Isomerases↗
PubMed1991

Chronopharmacokinetics of valproic acid following constant-rate administration in mice.

This study was carried out to investigate the circadian rhythm in the pharmacokinetics of valproic acid (VPA). ICR male mice, housed under a light-dark (12 h:12 h) cycle, were used in these studies. In the constant-rate administration study (536.3 or 1,072.6 micrograms/h), osmotic minipumps were implanted subcutaneously in mice. There was a significant circadian rhythm in plasma VPA concentrations: higher values were obtained in the light phase and lower values were found during the dark phase. A significant circadian rhythm also was shown for clearance (CL) of the drug: lower values were obtained in the light phase and higher values were demonstrated in the dark phase. In the intravenous administration study, VPA (50 mg/kg) was injected into a tail vein of the mice. Mean plasma VPA concentrations were significantly higher in mice injected with the drug at 1700 h than at 0100 h. The CL was higher, the volume of distribution (V) was larger, and the area under the curve (AUC) was smaller (p less than 0.05, respectively) in mice injected with the drug at 0100 h than at 1700 h. As the values of CL and V increased similarly during the dark period, there was no effect on half-life (t 1/2) and obviously on the elimination rate constant (K). These findings indicate that the circadian rhythms of plasma VPA concentrations observed after constant-rate administration are due to those of CL and V. To keep drug concentrations constant, the drug release rate from the osmotic minipump should be controlled according to the rhythm of drug pharmacokinetics.

Analysis of Variance↗
PubMed1991

Improving the ocular to systemic ratio of topical timolol by varying the dosing time.

This study was performed to determine whether the ratio of ocular to systemic absorption of topically applied timolol in the pigmented rabbit can be maximized by varying the time of drop instillation. Twenty-five microliters of 0.65% timolol maleate solutions were instilled into the pigmented rabbit eye at 6 AM, 12 PM, 6 PM, or 12 AM. The time course of timolol concentration in plasma and various eye tissues (conjunctiva, sclera, corneal epithelium, corneal stroma, aqueous humor, iris-ciliary body, and lens) was monitored with the use of reversed phase high-performance liquid chromatography (HPLC). Ocular timolol concentrations were approximately twice as high when the drug was administered at 12 PM than at 6 AM, 6 PM, or 12 AM, whereas timolol concentration in plasma was lowest when the drug was administered at 12 PM. It may, therefore, be possible to maximize the therapeutic index of topically applied timolol by administering the drug at 12 PM. Moreover, the possible influence of dosing time on the extent of ocular and systemic drug absorption must be considered when planning dosing schedules for topically applied ophthalmic drugs.

Absorption↗
PubMed1991

Pharmacokinetic basis for nonadditivity of intraocular pressure lowering in timolol combinations.

The authors determined whether the ocular absorption of topically applied timolol in the pigmented rabbit was affected significantly by coadministration with either pilocarpine or epinephrine in the same drop to explain the nonadditivity in intraocular pressure lowering (IOP) seen clinically. They instilled 25 microliters of 0.65% timolol maleate solution (equivalent to 0.5% timolol), both in the presence and absence of 2.6% pilocarpine nitrate or 1% epinephrine bitartrate, into pigmented rabbit eyes. The time course of timolol concentration in the conjunctiva, anterior sclera, corneal epithelium, corneal stroma, aqueous humor, iris-ciliary body, and lens was monitored for 360 min by using reversed-phase high-performance liquid chromatography. The area under the timolol concentration-time curve in all but one of the anterior segment tissues was reduced by 20-50% (mean, 40%) when timolol was coadministered with pilocarpine and by 20-70% (mean, 42%) when timolol was coadministered with epinephrine. Such an effect was not a result of alterations in corneal permeability or aqueous humor turnover rate, nor was it related to the extent of systemic absorption caused by pilocarpine and epinephrine. Rather, the reduction in ocular timolol absorption may have been caused by the accelerated washout of timolol by tears stimulated by the coadministered drugs and, to a lesser extent, by the loss of timolol through binding to the increased amount of tear proteins induced by the coadministered drugs. Thus, the nonadditivity in IOP lowering from timolol-pilocarpine and timolol-epinephrine combinations is probably caused by changes in precorneal timolol clearance.

Absorption↗
PubMed1990

Association of cephalic neural crest cells with cardiovascular development, particularly that of the semilunar valves.

The quail-chick chimera method was used to examine whether neural crest cells were associated with the formation of semilunar valves. From the metencephalon to somite 5, or from the otocyst to somite 3, left, right, or bilateral neural folds, including the neural crest, were transplanted. Among embryos used for the experiment, three into which left neural crest cells were transplanted, two into which right neural crest cells were transplanted, and two into which bilateral neural crest cells were transplanted had a morphologically normal heart. In these embryos, neural crest cells were found in all cusps of the aortic and pulmonary semilunar valves. Although neural crest cells have been thought to have no association with the formation of the semilunar valves, our experiment indicates that such association indeed occurs.

Animals↗
PubMed1990

Teratogenic effects of sodium valproate in the Jcl: ICR mouse fetus.

Sodium valproate was administered to Jcl:ICR mice in order to evaluate its teratogenicity. A single dose of 600 mg/kg of sodium valproate was injected intraperitoneally on gestational day 6, 7, 8 or 9. On day 18 of gestation, dams were laparotomized, and live fetuses were inspected for the presence of external and internal abnormalities. Exencephaly and urogenital abnormalities showed the highest frequency in the group treated on day 8, being recognized in about 60% and 10% of live fetuses, respectively. Cardiovascular abnormalities were found in the highest frequency in the group treated on day 7 (in about 30% of live fetuses). Incidence of tail abnormality was found to increase with delay in day of drug administration. Other abnormalities observed were cleft palate and digital malformation. Our study showed that a constellation of major abnormalities similar to the congenital valproate syndrome suspected in humans could be produced in the Jcl:ICR mouse fetus.

Abnormalities, Drug-Induced↗
PubMed1990

Trisomy 10p syndrome owing to maternal pericentric inversion.

A female infant with karyotype 46,XX,rec(10),dup p inv(10)(p11.2q25.2)mat is presented. She had both duplication of 10p and deletion of distal 10q, but only had the constellation of specific features characteristic of duplication of 10p.

Chromosome Inversion↗
PubMed1989

Alteration in hypnotic effect of pentobarbital following repeated agonistic confrontations in mice.

We investigated how repeated agonistic confrontations affect the hypnotic effect of pentobarbital (PB) in male mice, using a resident-intruder paradigm. PB concentrations in the cortex, midbrain and brainstem were determined. Agonistic confrontations were terminated after 10 or 20 attack bites, and were repeated for 5 consecutive days. Immediately after the last encounter, PB (55 mg/kg, IP) was administered to both resident and intruder mice. Compared to the control group, intruders exposed to 20 daily attack bites showed a significant prolongation of the latency to sleep and a shortening of the duration of sleeping time. At the stage of induction, no significant difference in brain PB levels was found between the "defeated" and control intruders. At the stage of recovery, however, the "defeated" intruders showed a significantly low level of PB in all brain areas. In contrast, attacking resident mice did not show any significant changes in either the hypnotic effect or regional brain concentration of PB. Because pretreatment with naloxone prior to daily agonistic confrontation antagonized the alteration in PB-induced hypnosis, it seems that endogenous opioid mechanisms may participate in this phenomenon. The present study indicates that susceptibility to a hypnotic drug can be altered by chronic social conflict experience.

Aggression↗
PubMed1989

Partial monosomy 5p and partial trisomy 5q due to paternal pericentric inversion 5(p15.1q35.1).

A male infant with karyotype 46,XY,rec(5),dup q,inv(5)(p15.1 q35.1)pat is presented. The proband showed growth and developmental retardation, complex cardiovascular abnormalities, inguinal hernia and microcephaly in addition to facial appearance and cat-like cry characteristic of the cri-du-chat syndrome. Growth and developmental retardation, and microcephaly noted in this patient were markedly more serious than those observed in patients either with partial monosomy 5p or with partial trisomy 5q alone.

Abnormalities, Multiple↗
PubMed1989

Association of congenital heart disease, blepharoptosis, and short stature.

We found 12 patients with congenital heart disease of unknown etiology complicated with blepharoptosis during a period from Sept. 1, 1981 to April 30, 1989. All the patients with congenital heart disease were acyanotic, including 10 with short stature. Among these 10, abnormalities of high frequency were intrauterine growth retardation (5 cases), mental retardation (5), microcephaly (3), epicanthus (4), high arched palate (4), sacral dimple (4), and distal axial triradius (3). It is postulated that the association of congenital heart disease, blepharoptosis and short stature might indicate pathogenetic relationships.

Blepharoptosis↗
PubMed1989

Acromesomelic dysplasia in a father and son: autosomal dominant inheritance.

A father and son with typical acromesomelic dysplasia are reported, with the father more severely affected than the son. The disease was thus apparently transmitted in an autosomal dominant fashion. This is at variance with the autosomal recessive mode of inheritance assumed from hitherto reported families.

Adult↗
PubMed1989

Sibs lacking characteristic features of duplication of distal 17q.

Two brothers with karyotype 46,XY,-16,+der(16),t(16;17)(q24.3;q25.1)pat are presented. It is commonly thought that duplication of distal 17q results in a clinically recognisable syndrome. Although our cases had several features often seen in patients with autosomal chromosome aberrations, they did not have any of the specific features found in other patients with this duplication.

Abnormalities, Multiple↗
PubMed1989

Chronotoxicity of sodium valproate and its mechanisms in mice: dose-concentration-response relationship.

A significant circadian rhythm of acute toxicity was demonstrated in mice with intraperitoneal (i.p.) injection of sodium valproate (VPA). The role of pharmacokinetics on the rhythms of the toxicity and electroshock seizure (ES) threshold was investigated. ICR male mice, housed under a light-dark (12:12) cycle, were injected intraperitoneally 1200 mg/kg for the acute toxicity study and 300 mg/kg for the anticonvulsant effect study. In the acute toxicity, the highest mortality was found when VPA was injected at 1700 and the lowest at 0900 or 0100. The time course of mean plasma and brain VPA concentrations after an injection of VPA was not different between mice injected at 1700 and mice injected at 0100. In the anticonvulsant effect, no significant circadian rhythm was demonstrated for both the ES threshold and the plasma VPA concentrations after i.p. injection, although a significant rhythm has been reported for them after oral administration. The results suggest that the circadian rhythm in the mortality after an i.p. injection of VPA may be due to the rhythm in the sensitivity of the central nervous system to the drug and that the mechanism underlying the rhythm of VPA acute toxicity is different from that of the anticonvulsant action of VPA. The route and the time of drug administration are essentially important to study the anticonvulsant effect and acute toxicity of VPA in mice.

Animals↗