Biomedical subjects

Toshio Takeuchi

Publications and source records attributed to Toshio Takeuchi.

23 records · Page 2Linked to original sources

PubMed2002

Changes of the physiological parameters of very low-birthweight infants with chronic lung disease treated with dexamethasone.

BACKGROUND: Dexamethasone is widely used for the treatment of chronic lung disease (CLD), but its mechanism of action is still not clearly understood. METHODS: Respiratory status, bodyweight, blood pressure, urine volume, fluid intake and nutrient intake were investigated in 12 infants with CLD during treatment with dexamethasone. RESULTS: The mean gestational age of the patients was 26.3 +/- 2.5 weeks and their mean birthweight was 807 +/- 232 g. Treatment with dexamethasone was started at a mean age of 41 +/- 23 days. The ventilatory index (VI) improved after treatment was started. Blood pressure and urine volume increased significantly after treatment, but weight gain was poor during this time. Fluid and nutrient intake did not change before and after treatment. The degree of improvement in the VI after treatment was significantly correlated with an increase in urine volume. CONCLUSIONS: The results suggest that a rise in blood pressure as a result of dexamethasone treatment and the subsequent diuretic effect of this rise may play a role in improvement in respiratory status.

Anti-Inflammatory Agents↗

PubMed2002

Potter sequence complicated by congenital cystic lesion of the bladder.

We report a case complicated by oligohydramnios, pulmonary hypoplasia, bilateral renal dysplasia, and cystic lesion of the bladder. He was clinically compatible with Potter sequence. Congenital cystic bladder is the rarest form of the bladder. We can find no report of Potter sequence complicated by cystic lesion of the bladder. This lesion was similar to multilocular bladder. The diagnosis was confirmed it by autopsy, magnetic resonance imaging, and urography after his death.

Abnormalities, Multiple↗

PubMed2002

Mass isolation of primordial germ cells from transgenic rainbow trout carrying the green fluorescent protein gene driven by the vasa gene promoter.

Mass isolation of live primordial germ cells (PGCs) was demonstrated for the first time in ectothermal vertebrates. To establish a stem cell-mediated gene transfer system in fish, a stem cell line that retains the ability to develop into gametes is necessary. PGCs are well suited for use as the initial material for such a stem cell line. We established transgenic rainbow trout (Oncorhynchus mykiss) strains carrying the green fluorescent protein (GFP) gene driven by a rainbow trout vasa-like gene (RtVLG) promoter/enhancer. Because GFP expression was specific to the PGCs, PGCs were successfully visualized in all developmental stages examined. Isolated genital ridges containing GFP-labeled PGCs were enzymatically dissociated. To isolate PGCs from the complex pools of dissociated genital ridges, GFP-labeled cells were sorted by flow cytometry. The sorted GFP-positive cells were large and round with a large nucleus, typical characters of PGC morphology. The expression of RtVLG was detected only in the GFP-positive cell population, confirming that these cells were PGCs. This simple and efficient technique to purify a large number of viable PGCs opens the way for establishing a stem cell line, which can differentiate into the germline. The purified PGCs would also be a novel tool for cellular and molecular study of vertebrate germline stem cells.

Animals↗

PubMed2002

Retinoic acid isomers produce malformations in postembryonic development of the Japanese flounder, Paralichthys olivaceus.

We previously reported that characteristic deformities were induced by retinoic acid (RA) treatment of the Japanese flounder, Paralichthys olivaceus, at 6-9 days post-hatching (dph). To evaluate the toxic potency of nuclear retinoid receptors in induction of deformities by RA, we here investigated the effects of retinoic acid isomers on postembryonic development of this species. Larvae were exposed to either 25 nM of all-trans RA (atRA), 9-cis RA (9cRA) or 13-cis RA (13cRA) at 6-9 dph. All RA isomers induced deformities in the lower jaw, caudal fin and vertebrae. In the lower jaw, growth retardation of the dentary was evident. In the vertebrae, the major abnormalities were hypertrophy of the centrum, central fusion, and an increase in the number of abdominal vertebrae. Caudal fin deformities included deformity of caudal bone complex and absence of the entire caudal fin. The absence of the hypural primordium at 12 dph was the first sign of abnormality in caudal fin development, and resulted in complete blocking of the caudal fin development. Among the RA isomers, atRA induced the most severe deformity in all skeletons examined. Retinoic acid receptor (RAR) expression was activated by atRA and 9cRA, and pitx2 expression was inhibited in the lower jaw by atRA and 9cRA. Vitamin D receptor (VDR) expression was specifically inhibited by atRA treatment, suggesting that RA inhibits the lower jaw growth by suppressing the expression of these genes. These results suggest that RA exerted toxic effects on the skeletal systems, mainly through the RAR pathway.

Animals↗

PubMedDate not supplied

Differentiation of chondrocytes and scleroblasts during dorsal fin skeletogenesis in flounder larvae.

In teleosts, the embryonic fin fold consists of a peridermis, an underlying epidermis and a small number of mesenchymal cells. Beginning from such a simple structure, the fin skeletons, including the proximal and distal radials and lepidotrichia (finrays), develop in the dorsal fin fold at the larval stage. Their process of skeletogenesis and embryonic origin are unclear. Using flounder larvae, we report the differentiation process for chondrocytes and scleroblasts prior to fin skeletogenesis and the effects of retinoic acid (RA) on it. In early larvae, the mesenchymal cells grow between the epidermis and spinal cord to form a line of periodical condensations, which are proximal radial primordia, to produce chondrocytes. The prescleroblasts, which ossify the proximal radial cartilages, differentiate in the mesenchymal cells remaining between the cartilages. Then, mesenchymal condensations occur between the distal ends of the proximal radials, forming distal radial primordia, to produce chondrocytes. Simultaneously, condensations occur between the distal radial primordia and peridermis, which are lepidotrichia primordia, to produce prescleroblasts. Exogenous RA specifically inhibits the mesenchymal condensation prior to the proximal radial formation together with the down-regulation of sonic hedgehog (shh) and patched (pta) expression, resulting in the loss of proximal radials. Thus, it was indicated that differentiation of the precursor cells of radials and lepidotrichia begins in the proximal part of the fin fold and that the initial mesenchymal condensation prior to the proximal radial formation is highly susceptible to the effects of RA. Lepidotrichia formation does not occur where proximal radials are absent, indicating that lepidotrichia differentiation requires interaction with the radial cartilages. To examine the suggestion that neural crest cells contribute to the medial fin skeletons, we localized the HNK-1 positive cells in flounder embryos and slug and msxb-positive cells in pufferfish, Fugu rubripes, embryos. That the positive cells commonly arrive at the proximal part of the fin fold does not contradict the suggestion, but their final destiny as radial chondrocytes or lepidotrichia scleroblasts, should be further investigated.

Alkaline Phosphatase↗