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Biomedical subjects

Y Fujino

Publications and source records attributed to Y Fujino.

At least 271 records · Page 15Linked to original sources
PubMed1986

Carbonic anhydrase activity in developing sea urchin embryos with special reference to calcification of spicules.

Eggs and embryos of the sea urchins Anthocidaris crassispina and Hemicentrotus pulcherrimus did not exhibit significant changes in carbonic anhydrase activity during early development. Acetazolamide inhibited enzyme activity in homogenates of embryos and inhibited the formation of calcified spicules in a culture of micromeres at concentrations between 40 and 100 microM. Acetazolamide allowed intact embryos to develop to quasi-normal plutei but inhibited calcium deposition in the spicules. It is suggested that carbonic anhydrase contributes to CaCO3 deposition in the spicule.

Acetazolamide↗
PubMed1986

Change in the activity of Cl-,HCO3(-)-ATPase in microsome fraction during early development of the sea urchin, Hemicentrotus pulcherrimus.

In sea urchin embryos, primary mesenchyme cells, descendants from micromeres produced at the 16-cell stage, form spicules or CaCO3 deposits in their skeletal vacuoles, at the post-gastrula stage. Micromeres isolated at the 16-cell stage also differentiate into spicule-forming cells during their culture at the same time schedule as in the embryos. The present study was planned to observe change in the activity of Cl-,HCO3(-)-ATPase, which was expected to contribute to the carbonate supply for CaCO3 deposition, during development. ATP-hydrolysis in the microsome fraction, obtained from embryos of the sea urchin, Hemicentrotus pulcherrimus, and from micromere-derived cells in culture was stimulated by Cl- and HCO3- in the presence of ouabain and EGTA. The ATP-hydrolysis was inhibited by ethacrynic acid, an inhibitor of Cl-,HCO3(-)-ATPase. The activity of Cl-,HCO3(-)-ATPase in embryos and in micromere-derived cells increased during development, keeping pace with the rate of calcium deposition in spicules. Formation of calcified spicules in the cultured micromere-derived cells was inhibited by ethacrynic acid. These results indicate that Cl-,HCO3(-)-ATPase plays an important role in the mechanism of CaCO3 deposition in the primary mesenchyme cells.

Adenosine Triphosphatases↗
PubMed1986

Bone marrow sinus and cell egress in human leukaemia: a morphometric study of core biopsies using wide-field electron microscopy.

Bone marrow biopsy specimens obtained from 24 untreated patients with several types of acute leukaemia (AL) and eight patients with chronic myelocytic leukaemia (CML) were prepared without decalcification for electron microscopy. A new type of transmission electron microscope (LEM 2000) was used for wide-field observation, and the venous sinuses were morphometrically evaluated on micrographs using an automatic image analyser. No differences were found between either AL or CML bone marrows and the controls in the diameter, circumference, or luminal and endothelial area of sinuses. No degenerative changes were observed in the sinus endothelium of either the AL or CML patients, but the adventitial cell cover in sinuses was significantly less in both AL (P less than 0.001) and CML (P less than 0.001) patients than in the controls, indicating a close relationship between the decrease in adventitial cell cover and increase in migrating leukaemia cells. In addition, the sinus endothelium in CML had significantly (P less than 0.03) more pores than in AL patients and three or more leukaemic cells in migration through the same large pore were occasionally found in the CML patients. These findings suggest that leukaemic cell migration in AL differs from that in CML.

Acute Disease↗
PubMed1985

The effects of several ion channel blockers and calmodulin antagonists on fertilization-induced acid release and 45Ca2+ uptake in sea urchin eggs.

The effects of calcium antagonists, diltiazem and verapamil, and calmodulin antagonists, chlorpromazine, N-(6-aminohexyl)-1-naphthalenesulfonamide hydrochloride (W-5) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7), were tested on two responses of the sea urchin egg to insemination: (1) H+ release; (2) Ca2+ uptake. It was found that calcium antagonists inhibited both processes, while calmodulin antagonists only inhibited H+ release but not Ca2+ uptake. Verapamil and diltiazem were effective to inhibit H+ release when added to the egg suspension up to 120 sec and W-7 was effective around 150 sec after insemination. Calcium antagonists became ineffective earlier than W-7 in inhibiting H+ release. A calmodulin-dependent step may thus occur linking the Ca2+ uptake and H+ release. 4,4'-Diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an anion channel blocker, also inhibited both Ca2+ uptake and H+ release. This result suggests that an uptake of anion(s) occurs along with Ca2+ uptake.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1985

Mechanism for electrosilent Ca2+ transport to cause calcification of spicules in sea urchin embryos.

Embryos of the sea urchin, Hemicentrotus pulcherrimus, kept in sea water containing the calcium antagonists, diltiazem and verapamil, or an anion transport inhibitor, 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS), during a developmental period between the mesenchyme blastula and the pluteus corresponding stage, became abnormal plutei with poorly developed arms and quite small spicules. Treatment with ethacrynic acid and furosemide, inhibitors of chloride transport, during the same period of development yielded quasi-normal plutei with poor spicules and somewhat developed arms. In late gastrulae, the inhibitory effects of these calcium antagonists and DIDS on the uptake of 45Ca2+ in whole embryos were as strong as those on 45Ca deposition in spicules, whereas the effects of chloride transport inhibitors on calcium deposition in the spicules were markedly stronger than on its uptake in whole embryos. Electrosilent uptake of Ca2+ seems to be established mainly by coupled influx of chloride in the cells which mediate spicule calcification, and by concomitant influx of anions in the other cells. In swimming blastulae, 45Ca2+ uptake was inhibited by calcium antagonists and DIDS, but not by chloride transport inhibitors. Ca2+ uptake probably becomes coupled with chloride influx only in embryos in which spicule calcification occurs.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1985

Effect of organic and inorganic mercury compounds on the growth of incisor and tibia in rats.

The pharmacological effects of methyl mercury chloride (MMC) and mercuric chloride (HgCl2) (2-16 mg/Kg per day subcutaneously, for 6 d) upon the growth were studied in the incisors and proximal tibiae of immature rats histologically. Lead acetate was used as a time marker. 1. Mercury compounds slightly affected the body weight gains of the rats but apparently inhibited the longitudinal growth of proximal tibia and the effect increased with higher dosages. 2. Mercury compounds definitely inhibited not only the longitudinal growth (incisor growth) but also the appositional growth (dentin formation) of incisal dentin. 3. The inhibitory effect on the growth was ranked as follows: bone growth greater than dentin formation greater than incisor growth. 4. The actions of MMC on the growth of incisors and proximal tibiae appeared gradually and the response was biphasic; stimulatory and then inhibitory. The inhibitory effect appeared even after the injection was discontinued and appeared more extremely than during the injections. 5. In HgCl2 groups the inhibitory effect on the growth appeared rapidly. The effect increased with higher dosages and became stronger as the injections were repeated. However, this effect was weakened promptly after the injection was discontinued. 6. The repeated injections of mercury compounds hardly affected the level of serum calcium but disturbed the calcification of incisal dentin. From the above-mentioned results a possible mechanism was discussed. It is suggestive that MMC acts directly upon a cell and is transported into it. Once MMC was introduced into a cell it is slowly demethylated to inorganic Hg and acts as the demethylated mercury. When accumulated mercury is slight in volume, it stimulates and then inhibits the cell function with increasing mercury. However HgCl2 binds directly with an effector cell membrane in loose fashion. This may cause the ready reversibility of the effect.

Animals↗
PubMed1984

Radiologic spectrum of rectal carcinoid tumors.

Radiographs of 12 carcinoid tumors of the rectum were reviewed and compared with pathologic findings. There was a good correlation between the radiologic and pathologic findings with respect to tumor invasion and extent. Nine tumors that radiologically presented a smooth round defect less than 2.0 cm in diameter did not invade the muscular layer and did not metastasize. Three tumors that presented a deep crater with an irregular edge greater than 2.0 cm were found to have invaded the muscular layer and metastasized to the lymph nodes or the liver. The double-contrast enema showed an excellent detection rate; no lesion was missed by it.

Adult↗
PubMed1983

[Clinical estimation of the relation between coronary artery disease and regional myocardial blood flow by continuous thermodilution with the multithermistor catheter].

To evaluate coronary hemodynamics more precisely in ischemic heart disease, great cardiac vein flow ( GCVF ) and coronary sinus flow (CSF) were simultaneously measured before and during atrial pacing by a continuous thermodilution technique with the multithermistor catheter in 10 patients with significant coronary stenosis (narrowing of the left anterior descending artery of 75% or more) (Group 1: CAD) and 12 cases with the normal coronary artery (narrowing of 25% or less) (Group 2: NonCAD ). GCVF reflects the anterior regional flow of the left ventricle and CSF reflects total left ventricular flow. Between the two groups, no significant differences were noticed in either resting GCVF or resting CSF. However, atrial pacing induced a reduction of coronary resistance (CR) and increasing regional myocardial blood flow in both groups in the same way, and the maximal pacing provoked anginal episode in CAD group in which both the percent decrease of coronary resistance (CR) (% delta CRant 25.3% and % delta CRt 23.3%) and the percent increase of regional myocardial blood flow (% delta GCVF 49.6% and % delta CSF 40.6%) were lower than those in NonCAD group (% delta CRant 42.3%, % delta CRt 37.6%, % delta GCVF 80.6%, and % delta CSF 68.3%, respectively). These data imply that resting coronary blood flow may be maintained as normal in patients with angiographically significant coronary stenosis, though coronary reserve probably decreased in these patients. In this respect, the continuous thermodilution technique using the multithermistor catheter may be useful for the clinical estimation of coronary hemodynamics induced by various interventions. This technique can be performed repeatedly for a short time and permits simultaneous assessment of venous blood flow draining from the anterior wall and of total left ventricular flow.

Cardiac Pacing, Artificial↗