Search PubMed⌕ Search

Biomedical subjects

N Takagi

Publications and source records attributed to N Takagi.

At least 271 records · Page 15Linked to original sources
PubMed1984

Simultaneous separation and sensitive determination of free fatty acids in blood plasma by high-performance liquid chromatography.

Fatty acids are separated by reversed-phase high-performance liquid chromatography after derivatization with a fluorescence reagent, 4-bromomethyl-7-acetoxycoumarin. Each derivative eluted from a column is successively hydrolysed by mixing it with an alkaline solution, and the produced fluorescence is detected. The derivatives of series of both saturated and unsaturated fatty acids (C6:0--C20:4) are simultaneously separated by a continuous gradient elution method using a methanol-based solvent containing acetonitrile. The quantitative detection of fatty acids is over a range of 5-1000 pmol per derivatization mixture. This method is applicable to the quantitative analysis of free fatty acids in normal human blood samples and blood samples from diabetic patients. Ten microliters of blood plasma are sufficient to carry out the determination. The analytical results show good recovery and good reproducibility. This sensitive method is very useful for the analysis of fatty acids in very low concentrations.

Acetonitriles↗
PubMed1984

The postauricular myogenic response in normal children and children with microtia.

The effect of the development of postauricular muscles on the postauricular myogenic response (PAR) was investigated in normal children and children with microtia. There were no differences between the PAR of normal children and that of the intact ear of children with microtia. The PAR obtained from the normal and microtic sides of children with unilateral microtia showed no significant differences as regards waveform, latency, threshold, or amplitude. Our findings suggest that the development of the postauricular muscle does not affect the PAR, and it seems difficult to explain the large individual variations in the PAR by intersubjective differences in muscle development.

Acoustic Stimulation↗
PubMed1984

Studies of the temporal relationship between the cytogenetic and biochemical manifestations of X-chromosome inactivation during the differentiation of LT-1 teratocarcinoma stem cells.

Previous biochemical studies have suggested that both X chromosomes produce gene products when cells of the LT-1 teratocarcinoma stem cell line are maintained in the undifferentiated state, and that dosage compensation, the biochemical manifestation of X inactivation, occurs when the cells are induced to differentiate in vitro (Martin et al., 1978). In this study the differentiation of LT-1 cells in vitro is described in detail, and data from cytogenetic studies of the time of X-chromosome replication in LT-1 cells are presented. They show that as long as the cells are maintained in the undifferentiated state both X chromosomes in each cell show the isocyclic replication pattern typical of a genetically active chromosome. However, when the LT-1 cells are induced to differentiate under appropriate conditions, one of the two X chromosomes in each cell of a large proportion of the population displays the allocyclic (either early or late) replication pattern typical of an inactive X chromosome. These data thus confirm that undifferentiated LT-1 cells contain two active X chromosomes and that X inactivation occurs in differentiating cultures of LT-1 cells. It is further demonstrated that there is a close temporal correlation between the biochemical and cytogenetic manifestations of the X-inactivation process. In addition, we observed that although X inactivation does not occur in the absence of morphological differentiation, it does not always occur when the cells differentiate in vitro.

Animals↗
PubMed1984

X chromosome inactivation in bone marrow cells of adult mice carrying Searle's X-autosome translocation: occurrence of the early-replicating inactive X chromosome.

Using BrdU labelling-acridine orange fluorescence staining and the expression of PGK-1 isozymes, we attempted to clarify the pattern of X chromosome inactivation in bone marrow cells from adult female mice heterozygous for Searle's X-autosome translocation. The asynchronously replicating X chromosome was always the morphologically normal one, and neither of the translocated X chromosomes showed allocyclic behavior. Unexpectedly, a substantial proportion of the allocyclic X chromosome apparently finished replication earlier than any other chromosomes of the cell. This early replicating allocyclic X chromosomes was judged to be as genetically inactive as the late replicating one, since the Pgk-1b allele on the normal X was never expressed in bone marrow cells. Study of karyotypically normal females and females carrying Cattanach's insertion showed that the early replicating X chromosome is not just a feature of the Searle's translocation in the adult bone marrow cells and may be either paternal or maternal in origin. This type of allocyclic X chromosome deserves attention in assessing X chromosome inactivation in female somatic cells.

Animals↗
PubMed1983

Allocyclic early replicating X chromosome in mice: genetic inactivity and shift into a late replicator in early embrogenesis.

The allocyclic X chromosome in early female mouse embryos undergoes DNA replication either late or early in the S phase. Earlier studies indicated that the early-replicating X chromosome is restricted to the trophectoderm and primitive endoderm cell lineages in which the allocyclic X is almost exclusively paternal in origin. There has been, however, no compelling evidence for the genetic inactivity of the early-replicating X chromosome and a shift from early to late replication or vice versa. The present study employing a combination of 3H-thymidine autoradiography and BrdU labeling-acridine orange fluorescence staining in day-6 female mouse embryos found that the early-replicating X chromosome can change directly into a late-replicating one. The activity state of the early-replicating X chromosome was examined by electrophoretic determination of the X linked enzyme, phosphoglycerate kinase (PGK-1), in tissues isolated from 6.0-day and day-8.5 Pgk-1a/Pgk-1b embryos. Only the maternally derived Pgk-1 allele was expressed in the proximal endoderm and extraembryonic ectoderm of 6.0-day and the chorion of 8.5-day embryos. Thus, the early-replicating, paternally derived X chromosome found in about 70%-80% of the cells in these tissues seems to be repressed like the late-replicating one.

Animals↗
PubMed1983

High-performance liquid chromatography of alpha-keto acids in human saliva.

alpha-Keto acids in human mixed saliva collected without stimulation were analysed by reversed-phase ion-pair high-performance liquid chromatography (HPLC). Several alpha-keto acids were found in saliva and their concentrations were: alpha-ketoglutaric acid (KGA), 221 +/- 142; pyruvic acid (PA), 7490 +/- 5600; alpha-ketoisovaleric acid (KIVA), 61 +/- 23; alpha-ketoisocaproic acid (KICA), 137 +/- 79; alpha-keto-beta-methylvaleric acid (KMVA), 41 +/- 19 nmol/dl (mean +/- SD, n = 40). Their levels proved to be lower than those in plasma, except that of PA. Their concentrations in saliva showed individual variation compared with those in blood.

Adult↗
PubMed1983

De novo X-chromosome inactivation in somatic hybrid cells between the XO mouse embryonal carcinoma cell and XY rat lymphocyte.

Polyethylene glycol-mediated cell fusion between the hypoxanthine phosphoribosyl transferase (HPRT) deficient XO mouse embryonal carcinoma cell line, PSA-6TG1, and thymus or spleen lymphocytes from the normal male WKA/Hok rat gave rise to 35 somatic hybrid cultures. Hybrid cells being products of either a 1 : 1 or a 2 : 1 fusion invariably had morphological characteristics of endodermal cells from early embryos. BrdU-acridine orange (AO) fluorescence microscopy revealed do novo appearance of a late or early replicating, presumably genetically inactivated, mouse X chromosome in a substantial proportion of virtually tetraploid (XXY) or hexaploid (XXXY) hybrid cells.

Animals↗
PubMed1983

Reversal of X-inactivation in female mouse somatic cells hybridized with murine teratocarcinoma stem cells in vitro.

A series of near-diploid embryonal carcinoma-like hybrid cells were obtained from polyethylene glycol mediated cell fusion between murine embryonal carcinoma cells (PSA-6TG1 or OTF9-63) having one X chromosome and thymocytes or bone marrow cells from female mice carrying Cattanach's or Searle's translocation. Prior to fusion with EC cells the somatic cells are presumed to contain only one active X chromosome. Following hybrid formation, the chronology of X chromosome replication and the expression of X-linked gene Pgk-1 indicated that all X chromosomes contributed by both parents were active in these hybrids. Experiments were performed to rule out the possibility that the hybrids were formed by fusion of EC cells with rare somatic cells in which both X chromosomes were active. Taken together the data indicate that within four days of fusion there is reactivation of the entire inactive X chromosome.

Alleles↗
PubMed1983

Karyotypic kinship between the blue fox (Alopex lagopus Linn.) and the silver fox (Vulpes fulva Desm.).

A karyotypic comparison between the blue fox and the silver fox revealed conservation of the chromosome arm as a unit, except for large heterochromatic blocks in 10 pairs of blue fox chromosomes and the complete absence of a common metacentric autosomal pair. This finding seems to indicate that their karyotypes evolved from a common ancestral karyotype, characterized by 70-76 acrocentric autosomes, mainly through a series of independent centric fusions.

Animals↗