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Biomedical subjects

T Kuwana

Publications and source records attributed to T Kuwana.

At least 73 records · Page 4Linked to original sources
PubMed1988

Reference limits of bone and liver alkaline phosphatase isoenzymes in the serum of healthy subjects according to age and sex as determined by wheat germ lectin affinity electrophoresis.

Wheat germ lectin affinity electrophoresis was employed for quantitating the bone and liver isoenzymes of alkaline phosphatase (EC 3.1.3.1) in serum and for determining the reference limits of each isoenzyme activity in 488 healthy individuals. Bone phosphatase activity was detected even after bone growth, accounting for 60-70% of the total activity. An increase in bone phosphatase activity occurred in older females, but there was a decrease in older males. Liver phosphatase activity gradually increased with age in both sexes, males showing higher activity than females at all ages. Wheat germ lectin affinity electrophoresis of serum alkaline phosphatase is a simple and useful method for quantitating bone and liver alkaline phosphatase activities.

Adolescent↗
PubMed1988

Extragonadal distribution of primordial germ cells in the early chick embryo.

Chick primordial germ cells (PGCs), after separation from the endoderm in early embryonic development, temporarily circulate via the blood vascular system and finally migrate into the gonadal anlagen. It has been noted by some authors that some PGCs are present in extragonadal sites in some vertebrates. In the present study, we examined the distribution and localization of PGCs in extragonadal sites in the chick embryo. PGCs were identified by periodic acid-Schiff staining with light microscopy. In embryos at stages 20-24 (PGCs are in the settlement stage in the gonadal primordium), approximately 20% of the total number of PGCs were observed in extragonadal regions. Approximately 90% of these ectopic PGCs were found in the head, mainly in the mesenchyme surrounding the neural tube. Even at stage 14 when PGCs were usually circulating in the blood vessels, some of the PGCs had emerged from the blood vessels and were detected in the extragonadal site. This pattern of distribution of ectopic PGCs in the head area is probably attributed to the earlier, dominant development of the capillary network, and to the sluggish capillary blood flow in that region, which allows intravascular PGCs to escape into the tissue.

Animals↗
PubMed1988

Interspecific melanocyte chimaeras made by introducing rat cells into postimplantation mouse embryos in utero.

Dissociated cells of whole midgestation rat embryos were injected into implanted albino mouse embryos on Day 8.5 of gestation in utero. This successfully produced viable interspecific chimaeras which were found to have pigmented hairs. Two of them had many pigmented hairs covering a large area of their bodies, including a forelimb and a hindlimb. The fact that some of the introduced rat cells differentiated into functional melanocytes suggests that embryonic cells of both species were able to interact with each other normally and that the foreign cells were kept from maternal immunological assault.

Animals↗
PubMed1987

Behavior of chick primordial germ cells moving toward gonadal primordium in vitro: scanning electron microscopic study.

Primordial germ cells (PGCs) from embryonic chick blood were cultured in vitro and the cells being attracted by the gonadal primordium (germinal ridge; GR) were studied by scanning electron microscopy (SEM). Immediately after confirming PGC locomotion by 16-mm time-lapse filming or time-lapse video recorder under the microscope, PGCs in various phases of locomotion were prepared for SEM, and their locomotion was analyzed. With the thin collagen layer as a substrate, the sequence of the PGC locomotion was as follows: 1) The PGC produced a small pseudopodium. 2) This pseudopodium enlarged to the GR, and PGC-substrate contact was consolidated around the periphery of the pseudopodium, while the body of PGC remained detached from the substrate. 3) Finally, the PGC as a whole moved toward the GR, being trailed by the process. The locomotion of the PGC on the thick collagen layer as a three-dimensional substrate was as follows: 1) The PGC protruded a pseudopodium in the direction of the GR. 2) This pseudopodium elongated through the collagen network. 3) The tip of the pseudopodium swelled and the main body of the PGC flowed into the swelling portion, leaving a slender cytoplasmic tail. 4) The tail was finally incorporated into the leading part of the cell. This behavior of the PGC seemed to reflect the features of interstitial PGC in vivo.

Animals↗
PubMed1986

Attraction of chick primordial germ cells by gonadal anlage in vitro.

The attraction of primordial germ cells (PGCs) by the gonadal anlage (germinal ridge; GR) in vitro has been demonstrated in the chick. PGCs were isolated from circulating blood of stage 13 embryos (Hamburger and Hamilton, 1951), placed between the GR and other embryonic tissues (neural tube, heart, allantois, liver) as controls separated by a distance of 170 microns on collagen-coated substrate, and cultured with modified medium 199 (Kuwana and Fujimoto, Anat. Rec., 209:337-343, 1984) containing 10% fetal calf serum (pH 7.3). The behavior of PGCs was observed for 3 hr by 16-mm time-lapse microcinematography. PGCs showed directional movement toward GR. Also, there was a stronger attractive effect on the PGCs by GR from stage 13 embryos than by GR from later stage embryos. These results suggest that PGCs are attracted by some factor emitted from GR.

Animals↗
PubMed1984

Locomotion and scanning electron microscopic observations of primordial germ cells from the embryonic chick blood in vitro.

The locomotion of chick primordial germ cells (PGCs) in vitro was observed using 16-mm time-lapse microcinematography and 35-mm time-lapse film. The PGCs isolated from circulating blood of stage 14 to 16 embryos (Hamburger and Hamilton, 1951) were cultured on a substrate of mesenchymal feeder cells obtained from the dorsal mesentery of stage 40 embryos, using modified medium 199 containing 10% fetal calf serum. The PGCs were found to move actively and to show a tendency to move along the longer axis of the underlying cells. The velocity of PGC locomotion averaged 26 micron/hr and reached 58 micron/hr as a maximum. After observation, the PGCs were processed for scanning electron microscopy. They had a considerable number of microvilli about 0.2 micron in thickness and some cytoplasmic blebs on their surfaces. It was observed that the PGCs in the migrating phase adhered to the substrate with its filopodia only at the leading edge, while a large part of the cell appeared to be apart from the substrate.

Animals↗
PubMed1983

Active locomotion of human primordial germ cells in vitro.

The locomotion of human primordial germ cells (PGCs) in vitro was observed using 16-mm time-lapse microcinematography. PCGs dissociated from 5- to 6-week human embryos were cultured in vitro using L-15 medium and human cord serum, and their movement on three artificial and two natural substrates was compared. Three-dimensional collagenous fiber nets reconstructed in the culture dish were found to be appropriate for PGC movement, although the cells did not migrate actively on any of the other substrates. The PGCs moved actively in an amoeboid fashion, extending pseudopodlike cytoplasmic processes toward the direction of movement. The direction of PGC locomotion was random. One PGC showed the most active motility; the velocity of the cell locomotion averaged 25 microns/h and it became extremely elongated, measuring 92 microns in its longer axis, whereas in the stationary state the PGC was rounded and measured 20 microns in diameter. Thus, the present study offers evidence that human PGCs can migrate actively.

Cell Movement↗
PubMed1981

Midpoint potentials of cytochromes in vesicles of anaerobically-grown Paracoccus denitrificans determined by the indirect coulometric titration method.

1. Multiplicity of redox components with spectral properties similar to b-type cytochromes was established in vesicles derived fro anaerobically-grown Paracoccus denitrificans. 2. Multiplicity of c-type cytochromes was not apparent either from low temperature spectroscopy or potentiometric titrations. 3. Cytochromes a + a3 and a component, only observable at liquid nitrogen temperature, with a spectral maximum at 582.5 nm were detected. 4. Redox cycling of electron transport components using the indirect coulometric titration method was a convenient means of pairing redox potentials and was reproducible in total absorbance changes, midpoint potentials and spectral maxima.

Anaerobiosis↗
PubMed1976

Spectroelectrochemical investigations of stoichiometry and oxidation-reduction potentials of cytochrome c oxidase components in the presence of carbon monoxide: the "invisible" copper.

Spectroelectrochemical studies are presented for the carbon monoxide complex of isolated, purified cytochrome c oxidase (EC 1.9.3.1) in solutions saturated with carbon monoxide. The results indicate a stoichiometry of three equivalents per oxidase-carbon monoxide complex molecule. Formal reduction potentials (Eo) of the two copper and one heme component at pH 7.0 were obtained by means of quantitative absorbance-charge titrations in the absence and presence of cytochrome c, and by means of a Nernstian "Minnaert" plot in the presence of cytochrome c. Analysis of the absorbance-charge curves from these titrations gave an indirect determination of the high potential, "invisible" copper component. The copper potentials in the carbon monoxide complex were found to be relatively unchanged with respect to those of the native enzyme. The Eo values obtained were: high potential ("invisible") copper (340 +/- 20 mV (NHE)), low potential copper (190 +/- 20 mV), and low potential heme (250 +/- 10 mV).

Carbon Monoxide↗