Search PubMed⌕ Search

Biomedical subjects

K Imai

Publications and source records attributed to K Imai.

At least 1,549 records · Page 86Linked to original sources
PubMed1977

Studies on cobalt myoglobins and hemoglobins. Preparation of isolated chains containing cobaltous protoporphyrin IX and characterization of their equilibrium and kinetic properties of oxygenation and EPR spectra.

Human hemoglobin containing cobalt protoporphyrin IX or cobalt hemoglobin has been separated into two functionally active alpha and beta subunits using a new method of subunit separation, in which the -SH groups of the isolated subunits were successfully regenerated by treatment with dithiothreitol in the presence of catalase. Oxygen equilibria of the isolated subunit chains were examined over a wide range of temperature using Imai's polarographic method (Imai, K., Morimoto, H., Kotani, M., Watari, H., and Kuroda, M. (1970) Biochim. Biophys. Acta 200, 189-196). Kinetic properties of their reversible oxygenation were investigated by the temperature jump relaxation method at 16 degrees. Electron paramagnetic resonance characteristics of the molecules in both deoxy and oxy states were studies at 77K. The oxygen affinity of the individual regenerated chains was higher than that of the tetrameric cobalt hemoglobin and was independent of pH. The enthalpy changes of the oxygenation have been determined as -13.8 kcal/mol and -16.8 kcal/mol for the alpha and beta chains, respectively. The rates of oxygenation were similar to those reported for iron hemoglobin chains, whereas those of deoxygenation were about 10(2) times larger. The effects of metal substitution on oxygenation properties of the isolated chains were correlated with the results obtained previously on cobalt hemoglobin and cobalt myoglobin. The EPR spectrum of the oxy alpha chain showed a distinctly narrowed hyperfine structure in comparison with that of the oxy beta chain, indicating that the environment around the paramagnetic center (the bound oxygen) is different between these chains. In the deoxy form, EPR spectra of alpha and beta chains were indistinguishable. These observations suggest that one of the inequivalences between alpha and beta chains might exist near the distal histidine group.

Binding Sites↗
PubMed1977

The further investigation on the gastric acid secretion in the primary hyperparathyroidism.

The gastric acid output was studied in the 11 patients of hyperparathyroidism before and after parathyroidectomy. The gastric acid output before operation was almost equal to the normal control in our hospital. After the correction of serum calcium by parathyroidectomy, the gastric acid output and serum gastrin were decreased. The decreased gastric acid output was recovered as the days passed since operation and approached to the preoperative level. The acid output in hyperparathyroidism was less in the case whose activity of alkaline phosphatase was more, which suggested that the calcium deposition on gastric mucosa might damage the parietal cell as the result of long lasting hypercalcemia.

Adolescent↗
PubMed1977

Radiographic observations of pyknodysostosis. Report of a case.

A case of pyknodysostosis in a 32-year-old woman has been reported. The patient presented typical skeletal changes, separated cranial sutures, open fontanelles, partial aplasia of the terminal phalanges of the fingers and toes, and brachyphalanges. The oral findings included lesions resembling periapical cementoma, hypoplasia of the maxilla and mandible, crowding of teeth, and a median raphe.

Abnormalities, Multiple↗
PubMed1977

Primary action of steroid hormone at the surface of amphibian oocyte in the induction of germinal vesicle breakdown.

An insoluble steroid derivative was prepared by the coupling of desoxycorticosterone with aminoethylated agarose beads. When the naked full-grown Xenopus oocytes were incubated in contact with the steroid-bound agarose beads, the dissociation of oocyte nuclei or the initial step in the maturation of amphibian oocyte was induced in 30-100% of total oocytes. The induction did not occur in the oocytes covered with follicle cells and when the naked oocytes were placed apart from the steroid-bound agarose beads in the medium. The above findings confirmed that the oocyte surface was a primary site for this particular steroid action, eliminating the possibility of participation of free steroid artifactually released from the agarose. The 105,000g supernatant fraction of oocytes showed no sign of the presence of steroid receptor. This was not inconsistent with the assumption mentioned above.

Animals↗
PubMed1977

Effects of protein deficiency on the biosynthesis and degradation of ribosomal RNA in rat liver.

Employing livers from rats fed on a protein-free diet for two weeks, the effects of protein deficiency on both biosynthesis and degradation of rRNA were investigated and the following results were obtained. 1. Protein deficiency led to a decrease of total liver RNA content per DNA to about 80% of that in normal rat liver. 2. From the kinetics of rRNA labelling with [14C]orotic acid in vivo, the half-lives of cytoplasmic rRNA's of normal and protein-deficient rat livers were determined to be 6.2 and 5.1 days, respectively. Furthermore, considering the pool size of rRNA in rat liver, the turnover rate of cytoplasmic rRNA was calculated to be 0.212 pmole/min/mg of nuclear DNA in normal rats and 0.240 pmole/min/mg of nuclear DNA in protein-deficient rats. 3. From the electrophoretic patterns of nucleolar RNA's of both groups of rat livers labeled with [14C]orotic acid, the time courses of the specific activities of nucleolar 45S, 32S, and 28S rRNA's were analysed and the half-life of each nucleolar RNA in both groups of rat livers was determined. Nucleolar 45S, 32S, and 28S RNA's had half-lives of 6.0, 15.9, and 26.5 min in normal rats, respectively, and 5.5, 19.4, and 22.9 min in protein-deficient rats, respectively Considering the pool size of each nucleolar RNA obtained from the leectrophoretic pattern, the turnover rates of 45S, 32S, and 28S RNA's were calculated to be the same, i.e., o.189 pmoles/min/mg of nuclear DNA, in normal rat liver and 0.372, 0.372, and 0.358 pmoles/min/mg of nuclear DNA in protein-deficient rat liver, respectively. 4. These results indicate that protein deficiency increased both the rate of degradation of cytoplasmic rRNA and that of nucleolar rRNA synthesis in rat liver. While in normal rat liver the rates of rRNA synthesis and degradation were rather similar, the rate of rRNA synthesis in protein-deficient rats was about 1.5 times higher than that of its degradation. Therefore, the decrease of total liver RNA content in protein deficiency might be accounted for by stimulated degradation of rRNA in the nucleus. 5. The activities of RNase in nuclear fractions of both groups of rat livers were compared. Both activities of nuclear acid RNase and especially that of the free form of alkaline RNase in protein-deficient rat liver were higher than those in normal rat liver.

Animals↗
PubMed1977

Ultrastructural evidence for neural crest origin of the malanotic neuroectodermal tumor of infancy.

A case of malanotic neuroectodermal tumor of infancy, which occurred in the anterior maxilla of a 3-month-old girl, was studied by electron microscopy. Polymorphic cellular elements were revealed to be present: large melanin-producing cells with some of the characteristics of a neuroepithelium, small non-pigmented cells resembling immature neuroblasts, and many intermediate forms resembling differentiating neuroblasts. All cell types clearly demonstrated ultrastructural features of neurogenic cells, e.g. neurite-like cytoplasmic processes, fine filaments and microtubules indistinguishable from those seen in normal neurites, synaptic-like structures, and neurosecretory-like vesicles. Based on these fine structures, the lesion was presumed to represent a hamartoma of primitive neuroectodermal cells with a tendency toward the differentiation into melanin-producing cells. The neural crest origin of this tumor was convincingly supported by ultrastructural analysis.

Cell Nucleolus↗
PubMed1977

Effect of hypolipidemia on testosterone-stimulated prostatic growth in castrated rats.

Hypolipidemia caused by Simfibrate feeding for 3 weeks reduced responses of weight and nucleic acid contents to testosterone administration in the ventral and dorsolateral prostates of castrated rats. However, the effect of testosterone on the contents of citrate, fructose, zinc and the activity of testosterone 5alpha-reductase in the glands of castrated animals was not modified by Simfibrate feeding.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1977

Demonstration of biogenic amines and adrenergic innervation in uveal malignant melanomas by the histoflurometric method.

Clinical and histologic studies were performed on 25 patients with malignant melanomas of the ciliary body and choroid. Portions of fresh tumor were quick frozen and processed by the histofluorometric technique to demonstrate the presence of biogenic amines. Separate portions of each tumor were fixed and processed for routine light microscopy. Specific fluorescence was visible in 21 of 23 pigmented neoplasms. Catecholamine-induced fluorescence of biogenic amines was related to tumor cell type. In two amelanotic tumors no specific fluorescence was seen.

Adult↗
PubMed1977

Depressant action of acetate upon the human cardiovascular system.

The effect of regular hemodialysis (HD) with dialyzate containing acetate was evaluated in 20 patients. After dialysis, a significant increase in limb blood flow was found (P less than 0.01) while the mean arterial blood pressure remained unchanged indicating a significant decrease in peripheral vascular resistance after HD (P less than 0.01). Cardiac function was evaluated using the ratio of the preejection period to left ventricular ejection time (PEP/ET); this value showed a significant increase after HD suggesting depression of cardiac function (P less than 0.001). The study was repeated substituting bicarbonate for acetate in 13 of the 20 patients. Under these conditions, limb blood flow and peripheral vascular resistance showed no significant change though mean arterial blood pressure decreased significantly (P less than 0.01). The ratio, PEP/ET, showed a significant increase after HD (P less than 0.01), but the value was significantly lower than that found after HD with dialyzate containing acetate (P less than 0.05). Changes in the serum levels of calcium, potassium, pH and body weight could not explain the differences found after HD with the two kinds of dialyzate. The results of the present study suggest strongly that acetate exerts a depressant action on the cardio-vascular system.

Acetates↗
PubMed1977

Inhibition of leucocyte migration by potassium chloride extracts of human tumor cells in ascites and from tissues.

Human gastric cancer-associated antigens were solubilized from fresh ascites and surgical specimens by 3M KCl extraction. The antigenicity of these extracts was measured by leucocyte migration inhibition assay with an improved modification devised in this laboratory. Antigens extracted mutually reacted with autologous and allogeneic leucocytes taken from cancer patients. The out of 11 (27%) patients and 7 out of 28 (25%) patients with various cancers showed positive migration index values against 13 ascites tumor cell antigens in the autologous and allogeneic reaction systems, respectively. Reactions were positive in 4 out of 10 patients with gastric cancer against autologous antigens, and in 10 out of 26 (38%) of the patients against allogeneic tumor antigens. On the other hand, one patient with gastric cancer reacted well with various sources of antigens extracted from allogeneic cells of gastric cancer, while the other patient with gastric cancer did not react with any of five gastric cancer antigens tested so far. These findings suggested that the cell-mediated immune response of patients with gastric cancer against autologous and allogeneic tumor antigens extracted was detectable in the test system. It is considered at present that the eM KCl antigen may be relate to human leucocyte antigen, and some common antigenic reactants capable of reacting with several gastric cancer may be involved in this reaction.

Antigens, Neoplasm↗
PubMed1977

Immobilization hypercalcemia in spinal cord injury.

Four patients having high-level quadriplegia developed elevated serum calcium concentrations (11 to 15.8 mg/100 ml) within three months of injury. All were young males (ages 15 to 19 years) and quadriplegic (C4-C7). Presenting symptoms were nausea, vomiting, polydipsia, polyuria and lethargy. In two patients severe muscle wasting and cachexia with clinical symptoms developed and persisted for several months. Laboratory studies in all patients showed negative calcium balance with hypercalciuria. Reduced renal function was seen in all patients but returned to normal with return of normal serum calcium. Alkaline phosphatase level was normal in three and elevated in one. Serum parathormone levels were normal. Roentgenograms revealed diffuse demineralization. Nephrocalcinosis and soft tissue calcifications developed in one patient. Primary treatment included reduced calcium intake, correction of dehydration, sodium infusion and remobilization. Corticosteroids, oral phosphates, furosemide and mithramycin were used with varying success to control prologned symptoms and severe hypercalcemia.

Adolescent↗
PubMed1977

Effect of estracyt on the rat prostate.

Two types of experiments were performed to elucidate the estrogenic effect of estracyt on the ventral and immature rats that had received injections of testosterone; then changes in weight of accessory rats and changes in weight of the total body, the ventral and the dorsolateral prostates, and adrenal gland, and changes in activities of testosterone 5alpha-reductase, alkaline phosphatase, and arginase of both lobes of the prostates were examined. In the second experiment, estracyt was injected into castrates rats and immature rats that had received injections of testosterone; then changes in weight of accessory sex organs were determined. Because similar changes were induced by treatment of animals with estradiol-17beta, it was concluded that the effect of estracyt on the prostates was most likely attributable to the estrogenic effect of the drug.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗