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Biomedical subjects

Y Takuma

Publications and source records attributed to Y Takuma.

At least 19 recordsLinked to original sources
PubMed2005

Successive changes in tissue migration capacity of developing larvae of an intestinal nematode, Strongyloides venezuelensis.

Infective larvae of an intestinal nematode, Strongyloides venezuelensis, enter rodent hosts percutaneously, and migrate through connective tissues and lungs. Then they arrive at the small intestine, where they reach maturity. It is not known how S. venezuelensis larvae develop during tissue migration. Here we demonstrate that tissue invasion ability of S. venezuelensis larvae changes drastically during tissue migration, and that the changes are associated with stage-specific protein expression. Infective larvae, connective tissue larvae, lung larvae, and mucosal larvae were used to infect mice by various infection methods, including percutaneous, subcutaneous, oral, and intraduodenal inoculation. Among different migration stages, only infective larvae penetrated mouse skin. Larvae, once inside the host, quickly lost skin penetration ability, which was associated with the disappearance of an infective larva-specific metalloprotease. Migrating larvae had connective tissue migration ability until in the lungs, where larvae became able to settle down in the intestinal mucosa. Lung larvae and mucosal larvae were capable of producing and secreting adhesion molecules.

Animals↗
PubMed2000

Phase transformation behavior in a multipurpose dental casting gold alloy during continuous heating.

Phase transformation in a multipurpose dental casting gold alloy during continuous heating was studied by electrical resistivity measurements, hardness tests, X-ray diffraction and scanning and transmission electron microscopy. The behavior can be explained by the following reaction sequences in the nodule: alpha1(fcc) + alpha2(L1(2)) --> alpha1(fcc) + alpha2(L1(2)) + beta(L1(0)), where fcc is face centred cubic. A discontinuous precipitation with very fine nodules contributed to the hardening and the growth produced the softening. This multipurpose gold alloy is characterized by the introduction of a PtZn ordered phase with L1(0) structure instead of a CuAu I phase.

Journal Article↗
PubMed2000

Current therapy for West syndrome in Japan.

We sent questionnaires concerning the current therapy for West syndrome to 208 institutions at which pediatric care members of the Japan Epilepsy Society were working. Of these, 129 (62%) institutions responded. Vitamin B6 was the preferred first-line drug, followed by the combination of vitamin B6 and valproate or monotherapy with valproate. Corticotropin was the third choice among the drugs. The dosage of corticotropin was lower than previously reported. The treatment of West syndrome is not well established at present and further research is needed to improve the therapeutic protocol.

Adrenocorticotropic Hormone↗
PubMed1999

Phase transformations and age-hardening behaviors related to Au3Cu in Au-Cu-Pd alloys.

Phase transformation behaviors in Au-Cu-Pd alloys were investigated by means of electrical resistivity measurements, hardness tests, X-ray diffraction and transmission electron microscopy. Anisothermal and isothermal annealing were performed. Two types of phase transformations were found, namely related to the single phase of Au3Cu and the coexistent phase of Au3Cu and AuCu I. The latter produced more remarkable hardening than the former. Hardening was brought about by the antiphase domain size effect of Au3Cu ordered phase in the single phase and by the formation of AuCu I ordered phase in the Au3Cu ordered matrix. There are three modes of phase transformation in the coexistent region depending on the composition. Each sequence is discussed.

Copper↗
PubMed1999

Phase transformation mechanisms in (AuCu)1-xPdx pseudobinary alloys by direct aging method.

Phase transformation mechanisms in the AuCu-Pd pseudobinary system were studied by means of electrical resistivity measurements, hardness tests, X-ray diffraction and transmission electron microscopy. A direct aging method was employed to eliminate the otherwise unavoidable ordering that takes place rapidly during quenching into ice brine, hence it is important to distinguish the ordering processes with and without an incubation period. Three phase transformation modes occurred, namely; ordering at grain boundaries and in the grain interior with nucleation and growth mechanism after incubation, and spinodal ordering without any incubation period. The age-hardening of the alloys examined was attributed to AuCu I ordering. Nucleation and growth mechanism followed by twinning occurred in the specimens aged at higher temperatures, while spinodal ordering was seen in specimens aged in lower temperature. The spinodal ordering temperature of AuCu-Pd alloys increased according to Pd content.

Copper↗
PubMed1999

Isothermal age-hardening behaviour in a multi-purpose dental casting gold alloy.

The isothermal age-hardening behaviour of a multi-purpose dental casting gold alloy was investigated by means of hardness testing, X-ray diffraction study, scanning electron microscopic observations and energy dispersive spectroscopy. By ageing of the solution-treated specimen at 400-500 degrees C, two phases of the Au-rich alpha 1 phase with an f.c.c. structure and the alpha 2 phase with an ordered f.c.c. structure based on Pt3In were transformed into three phases of the alpha 1 phase, the alpha 2 phase and the beta phase with an ordered f.c.t. structure based on PtZn. Hardening was attributed to the fine nodular precipitation resulting from the formation of the beta phase in the alpha 1 matrix. Softening was due to the coarsening of the fine nodular precipitates as the result of consumption of the alpha 2 phase.

Copper↗
PubMed1998

Cerebrospinal fluid somatostatin in West syndrome: changes in response to combined treatment with high-dose pyridoxal phosphate and low-dose corticotropin.

Eighteen children with West syndrome (5-11 months of age) were selected to receive an oral dose of pyridoxal phosphate, (20-50 mg/kg) for 14 d. Seizures disappeared in one patient. The remaining 17 patients were treated with 0.01 mg/kg synthesized corticotropin intramuscularly for 2 weeks as an additional therapy. Seizures disappeared in all 17 patients within a few days after initiation of the corticotropin. Levels of somatostatin in the cerebrospinal fluid were as follows: 61.0+/-10.7 pg/ml before therapy, 34.2+/-6.4 pg/ml during pyridoxal phosphate therapy, and 26.8+/-4.2 pg/ml after 2 weeks corticotropin therapy. Somatostatin levels in untreated patients were higher (p < 0.05) than those of age-matched controls (35.7+/-11.8 pg/ml) and decreased (p < 0.05) after pyridoxal phosphate treatment. Somatostatin is a hypothalamic tetradecapeptide with excitatory effects on neurons and pyridoxal phosphate might subclinically influence neuronal excitation.

Adrenocorticotropic Hormone↗
PubMed1998

ACTH therapy for infantile spasms: a combination therapy with high-dose pyridoxal phosphate and low-dose ACTH.

Combination therapy consisting of high-dose pyridoxal phosphate (40-50 mg/kg/day) and low-dose synthetic ACTH (0.01 mg/kg/day) was prescribed in 28 children with infantile spasms. Monotherapy with pyridoxal phosphate provided excellent seizure control in 3 of the 28 (11%) patients. ACTH was subsequently added to the regimen of the remaining 25 patients. As of 1 month after discontinuing the ACTH treatment, 21 of the 25 (84%) patients had experienced no seizures. The mean interval until seizure control was achieved was 4.1 days after the start of treatment with ACTH. The 21 patients have been monitored for a mean of 34.9 months (range 2-81 months); 6 patients (29%) have had recurrences of infantile spasms, and 10 (48%) have experienced normal development. Fourteen of the 28 patients (50%) have had transient increases in liver enzymes, but none of the patients developed more serious side effects.

Age of Onset↗
PubMed1997

Randomized, controlled trial of high-dose intravenous pyridoxine in the treatment of recurrent seizures in children.

To determine the efficacy of pyridoxine in treating seizures, 90 infants and children with recurrent convulsions primarily due to acute infectious diseases were enrolled in the present study. Forty patients were treated with high-dose pyridoxine (30 or 50 mg/kg/day) by intravenous infusion, and 50 subjects served as controls. Antiepileptic drugs and other therapies were similar in the two groups except for pyridoxine. Clinical efficacy criteria were based on the frequency of convulsions per day and on the duration of individual seizures after therapy was initiated. The results indicated that total response rates in the pyridoxine group and control group were 92.5% and 64%, respectively (chi-square = 14.68, P < .001). After initiation of therapy, seizures resolved after 2.4 +/- 1.4 days in the pyridoxine group and after 3.7 +/- 2.0 days in the control group (t = 3.67, P < .001). No adverse effects of pyridoxine were apparent during the observation period. We conclude that pyridoxine is an effective, safe, well-tolerated, and relatively inexpensive adjunct to routine antiepileptic drugs for treatment of recurrent seizures in children.

Anticonvulsants↗
PubMed1996

Combination therapy of infantile spasms with high-dose pyridoxal phosphate and low-dose corticotropin.

A new combination therapy, high-dose pyridoxal phosphate (40 to 50 mg/kg daily) and low-dose corticotropin (0.01 mg [0.4 IU]/kg daily), was tried in 28 children with infantile spasms. Monotherapy with pyridoxal phosphate provided excellent seizure control in three (11%) of the 28 subjects. Corticotropin was subsequently added to the regimen of the remaining 25 patients. At 1 month after discontinuing corticotropin, 21 (84%) of the 25 patients experienced no seizures, and 22 (88%) of the 25 showed improvement in their electroencephalographic findings. The mean interval until achievement of seizure control was 4.1 days after the initiation of corticotropin. The outcome in the 21 patients has been followed for a mean period of 34.9 months (range, 2 to 81 months). Of these 21 patients, six (29%) have had relapses of infantile spasms, and 10 (48%) have experienced normal development. Transient increases in liver enzymes occurred in 14 (50%) of the 28 patients, but none of the patients developed more serious side effects. The investigators conclude that combination therapy with high-dose pyridoxal phosphate and low-dose corticotropin is a promising new therapy.

Adrenocorticotropic Hormone↗
PubMed1994

Viability of one-cell bovine embryos cultured in vitro: comparison of cell-free culture with co-culture.

In this study, the quality (number of cells) and pregnancy rates of bovine blastocysts produced by in vitro maturation/in vitro fertilization (IVM/IVF) following cultivation in either cell-free culture or co-culture were compared. Bovine one-cell IVM/IVF embryos obtained 6 h after insemination were stripped of cumulus cells and assigned to either cell-free culture or co-culture with granulosa cell monolayers for 9 days (Expt 1) or 10 days (Expts 2 and 3). In Expt 3, day-7 (day 0 = day of insemination) blastocysts, day-8 expanded blastocysts and day-9 hatched blastocysts were air-dried, fixed and stained to determine the number of cells. Expanded blastocysts obtained in Expt 1 were cryopreserved using propylene glycol as a cryoprotectant and were used later for embryo transfer. There were no significant differences between cell-free culture and co-culture in the percentage of one-cell embryos that developed to 2- to 16-cells (66.7% versus 72.4% for Expt 1, 71.0% versus 78.2% for Expt 2). However, significantly more (P < 0.05) of the one-cell embryos co-cultured with granulosa cell monolayers developed to morula, blastocyst and expanded blastocyst stages compared with those in cell-free culture (35.0 versus 27.1%, 25.1 versus 14.2%, 15.6 versus 5.4% for Expt 1; 37.6 versus 24.0%, 25.7 versus 11.0%, 16.8 versus 3.0% for Expt 2). Only embryos co-cultured with granulosa cell monolayers hatched (Expt 2). Embryos co-cultured with granulosa cell monolayers also had higher (P < 0.01) numbers of cells (92 +/- 42 versus 56 +/- 21 for blastocysts, 149 +/- 53 versus 81 +/- 29 for expanded blastocysts).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Co-culture of in vitro fertilized bovine embryos with different cell monolayers.

The effects of different cell monolayers on in vitro development of early bovine embryos derived from in vitro maturation and fertilization were examined in this study. Early embryos (four to eight cells) were randomly allocated to bovine granulosa cell (GC), oviductal cell (OC), or uterine cell (UC) monolayers in Exp. 1 and to GC, skin cell (SC; from 10-d-old chicken embryos), testicular cell (TC; from 10-d-old mouse), and liver cell (LC; from 10-d-old chicken embryos) monolayers in Exp. 2, and cultured for 6 d at 38.6 degrees C in a humidified atmosphere of 5% CO2 in air. The culture medium was 12.5 mM HEPES TCM 199 supplemented with 1% calf serum and 1 mM sodium pyruvate. In Exp. 1, the percentage of four- to eight-cell embryos that developed to blastocysts on GC, OC, and UC monolayers was 26.9 (28/104), 37.5 (39/104), and 39.2 (40/102), respectively. In Exp. 2, the percentage of four- to eight-cell embryos that developed to blastocysts on GC, SC, TC, and LC monolayers was 53.3 (40/75), 42.9 (33/77), 49.3 (37/75), and 44.3 (35/79), respectively. There were no significant differences in development among groups in either experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Monotherapy for childhood epilepsies with zonisamide.

Zonisamide was tried on 44 children, 18 girls and 26 boys, from 8 months to 15 years of age at the start of the trial. In 6 children the drug has been stopped because of side effects. The drug was introduced at a dose of 2-4 mg/kg/day and increased to 12 mg/kg/day unless a satisfactory response occurred at a lower dose. A 100% control of seizures was achieved in 5 of 5 cases of idiopathic generalized epilepsies, in 7 of 8 cases of symptomatic generalized epilepsies, in one of one case of idiopathic partial epilepsies, and in 17 of 24 cases of symptomatic partial epilepsies. The main side effect was drowsiness, especially during the introduction.

Administration, Oral↗
PubMed1990

Fertilisation of bovine oocytes by the injection of immobilised, killed spermatozoa.

Immobilised (killed) bovine spermatozoa were microinjected into bovine oocytes matured in vitro and cultured for six to nine days in vitro. A co-culture system with cumulus cells was used for the embryonic development. After one to two, three to four, five to six and seven to eight days the proportions of the oocytes which had developed to the two to four-cell, six to 12-cell, morula and blastocyst stages were 12.0 per cent (61 of 507), 9.3 per cent (47 of 507), 5.9 per cent (30 of 507) and 7.8 per cent (nine of 115), respectively. In contrast, none of the sham-operated group developed beyond the six-cell stage. This is the first report to show that bovine oocytes matured in vitro can undergo cleavage to the blastocyst stage after the injection of sperm in vitro. In addition, normal calves were obtained from the transfers of some of the embryos to recipient cows.

Animals↗
PubMed1990

[Changes in thyroid function during ACTH therapy in patients with infantile spasms].

Serum triiodothyronine (T3), free T3, thyroxine (T4) and free T4 levels were measured before and immediately after daily ACTH-Z therapy (0.01 mg/kg/day, 1-2 weeks) for patients with 9 cases of infantile spasms and one case of myoclonus epilepsy. In some of them, serum reverse T3 (rT3) and thyroxine binding globulin (TBG) levels were also measured. All patients became seizure free after ACTH-Z therapy. Before ACTH-Z therapy, all of the hormone levels were within normal limits. Serum T3 and free T3 levels were markedly decreased after daily ACTH-Z therapy, and serum T4, free T4 and TBG levels were moderately decreased after the therapy. 1-6 weeks after the daily treatment, all of these hormone levels returned to pretreatment levels. Serum rT3 levels did not change after ACTH-Z therapy. These results suggest that the effect of long-term daily ACTH-Z therapy is very critical to the immature brain, and conventional ACTH-Z therapy has to be reconsidered.

Adrenocorticotropic Hormone↗
PubMed1989

[Changes in anterior pituitary function during ACTH therapy of patients with infantile spasms].

Serum cortisol, prolactin (PRL), TSH, GH, LH and FSH levels were measured before and immediately after daily ACTH-Z therapy (0.01 mg/kg/day, 1-2 weeks) for 5 patients with infantile spasms and one patient with myoclonus epilepsy. Total number of ACTH-Z therapy were 8 times, and all patients became seizure free after ACTH-Z therapy. In 6 occasions, TRH, LH-RH and insulin tolerance tests were performed before and after daily ACTH-Z therapy. Serum cortisol levels were significantly increased after daily ACTH-Z therapy but all other hormone levels were significantly decreased. In TRH and LH-RH tolerance tests, peak levels and increments of PRL, LH and FSH were significantly decreased after daily ACTH-Z therapy and those of TSH were mildly decreased. In one case insulin tolerance test revealed an adequate decrease of blood glucose before and after ACTH-Z therapy, and there was a poor GH response after ACTH-Z therapy. Daily ACTH-Z therapy was thought to suppress secretion of anterior pituitary hormones.

Child, Preschool↗