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Y Enoki

Publications and source records attributed to Y Enoki.

At least 55 records · Page 3Linked to original sources
PubMed1989

Hb Hope, beta 136(H14)Gly----Asp, in a diabetic Japanese female and its functional characterization.

A beta-variant hemoglobin, first misjudged as a marked elevation of Hb A1, was found in a 68-year-old Japanese female with diabetes mellitus. This hemoglobin was isolated by Bio-Rex 70 chromatography combined with chromatofocusing, and was found to be Hb Hope, beta 136(H14)Gly----Asp, by classical and high performance liquid chromatographic peptide mapping techniques. Intrinsic oxygen affinity of this hemoglobin was approximately one-third as compared with that of Hb A0. This property was still observed in the constituent beta subunits isolated. Effects of such allosteric effectors as H+ (at a fixed concentration of Cl-), anion (Cl-), 2,3-diphosphoglycerate and carbon dioxide were more or less depressed. Among others, a marked reduction in the carbamate effect should be noted in a structural interpretation of the functional modifications. Subunit cooperativity, on the contrary, was not different from that in Hb A0 (n = 2.8-2.9). Explanation of these altered functions were attempted on the basis of the altered structure. The reduced stability of Hb Hope is also described.

Aged↗
PubMed1989

[Clonal evolution in tumor cell population].

Clonal evolution which characterizes malignant tumors is the consequence of two antagonizing forces acting on the tumor cell population, namely, forces of diversion and conversion. The former makes cells to diverge through genetic and epigenetic instabilities which are the built-in characteristics of malignant cells. Possible causes of genetic instability are discussed. These include mistakes in DNA synthesis by an error-prone DNA polymerase, the nucleotide pool distartion and the overreplication of replication origins, abnormal DNA repair, high rate recombination, by expression of fragile sites and possibly by expression of retrotransposons, frequent nondisjunction of chromosomes as a consequence of gene dosage inbalance, and abnormal DNA methylation. The second force makes the resulting tumor cell population with heterogenous phenotypes to converge through selection by host defence mechanisms, competition for nutrients and oxygen among tumor cells, to cell interactions within tumor and between surrounding normal tissues. Genetic tagging of tumor cells with pSV 2neo facilitates the analysis of clonal evolution which results from diversion and conversion of tumor cells. Selective growth and metastasis of a clone in a mouse sarcoma population was demonstrated. Generation of dominant clones as well as drug resistant clones in tumor can be studied with this method.

Animals↗
PubMed1989

[Erythrocyte 2,3-diphosphoglycerate in muscular dystrophy].

Muscular dystrophy patients fall in respiratory failure in the terminal stage. Erythrocyte 2,3-diphosphoglycerate (2,3-DPG) is an important regulator of oxygen release, as it affects the position of the oxyhemoglobin dissociation curve. In order to survey the internal respiration in these patients, we studied the erythrocyte 2,3-DPG which regulates oxygen transport function. The concentration of erythrocyte 2,3-DPG was determined in 27 cases with Duchenne type muscular dystrophy and 10 cases with myotonic dystrophy (MyD). We analyzed the relation of erythrocyte 2,3-DPG to spirogram, arterial blood gas and acid-base analysis in these patients. 14 normal males were used as controls. In control subjects, the mean concentration ratio of 2,3-DPG and hemoglobin (DPG/Hb) was 0.880 +/- 0.072. 18 cases of DMD and 9 of MyD, which showed more than 45 torr of Pco2 in arterial blood gas, revealed 0.823 +/- 0.053 and 0.814 +/- 0.092 of DPG/Hb respectively. These values were significantly lower than that of controls. DPG/Hb correlated to % VC, Pao2, Paco2, pH, HCO3 and BE in DMD, but no relation to these parameters in MyD. The low ratio of DPG/Hb in erythrocyte was considered to be metabolic compensation of respiratory failure in DMD. On the other hand, 2,3-DPG of MyD seemed to be also affected by any other factors in addition to respiratory failure.

2,3-Diphosphoglycerate↗
PubMed1988

Effects of high O2 affinity of blood on oxygen consumption (VO2) of dog gracilis muscle at varying O2 delivery.

To clarify the influence of high O2-affinity blood on oxygen consumption by peripheral tissue, we perfused the dog gracilis muscle alternately with normal and low P50 blood at constant CaO2 and varying blood flows. VO2 was plotted against O2 delivery which was a product of CaO2 and blood flow. VO2 of the resting dog gracilis muscle was O2 delivery-dependent below a critical O2 delivery of 0.40 ml/min.100g, but became delivery-independent above this level. This relationship was essentially the same as that observed in rat skeletal muscle (Kolár and Janský, 1984), and was independent of the O2 affinity of blood, both qualitatively and quantitatively, although the PVO2 was significantly lower in the perfusions with the high affinity blood than in those with normal blood. The average PVO2 value by which the delivery-dependent and -independent VO2 regions were separated decreased from 33 Torr in the normal perfusions to 20 Torr in the high O2 affinity perfusions. In conclusion, the elevation of blood O2 affinity does not induce any reduction in VO2, and thus hypoxia, in resting skeletal muscle under normoxic conditions when O2 delivery is not below the critical level.

Animals↗
PubMed1988

Wide variation of myoglobin contents in gizzard smooth muscles of various avian species.

We determined myoglobin contents of gizzards (muscular stomach) and breast muscles in 34 avian species by a modification of Reynafarje's spectrophotometric procedure. The birds were apparently differentiated into two groups in respect of the gizzard, one with a high myoglobin content (7.74 +/- 1.81 mg/g muscle) and the other with a low (1.54 +/- 0.41 mg/g). In the former group of 15 species all but one were herbivorous, and all but one were carnivorous or else omnivorous in the latter group of 19 species. The myoglobin level was considered to closely correlate with mechanical performance and therefore oxygen demands of the gizzards. It might also be relevant to a circulatory situation during the tonic contractions of this organs.

Animals↗
PubMed1988

Effects of cadmium on in vitro and in vivo erythropoiesis: erythroid progenitor cells (CFU-E), iron, and erythropoietin in cadmium-induced iron deficiency anemia.

Effects of cadmium (Cd) on in vitro and in vivo erythropoiesis in rats were studied by methylcellulose colony assay. Cd suppressed the in vitro growth of late erythroid progenitors (CFU-E) in a dose-dependent fashion and did not lose its inhibitory potency with increasing doses of erythropoietin (EPO). In addition, in marrow suspension cultures, Cd did not significantly influence 59Fe incorporation into both the cells and heme, and the Cd dose-responsive inhibition curve of the number of living cells was similar to that of CFU-E. These results suggest that the suppression of CFU-E colony formation by Cd is not due to the blocking of either EPO action to stimulate the growth of CFU-E or the iron incorporation into the cells ahd heme, but due to its direct cytotoxic effect. The colony suppression by Cd could be prevented by adding metallothionein to the cultures. On the other hand, oral administration of Cd to animals (100 mg/liter in drinking water) induced an iron deficiency anemia characterized by microcytic hypochromic red cells, decreased plasma iron, and increased total iron binding capacity. Marrow CFU-E density steadily increased as plasma iron decreased due to Cd administration and reached a plateau after 50 days. Plasma EPO titers were also found to be elevated in such a Cd-induced anemia. Parenteral iron administration during the Cd drinking period could completely prevent the development of iron deficiency anemia and the increase of both CFU-E and plasma EPO. There was a hyperbolic correlation between CFU-E and plasma iron or transferrin saturation. These results demonstrate that oral CD administration produces bone marrow hyperplasia at the CFU-E level due to iron deficiency.

Anemia, Hypochromic↗
PubMed1987

Plasma erythropoietin assay by a fetal mouse liver cell culture method with special reference to effective elimination of erythroid colony inhibitor(s) in plasma.

Methods for the elimination of an inhibitor(s) of erythroid colony formation from plasma were examined in an attempt to measure genuine plasma erythropoietin (Epo) activities with an erythroid colony-forming assay using fetal mouse liver cells. Acid-boiling-chloroform (ABC) treatment was concluded to be the best method because the plasma thus treated stimulated colony formation most and contained the least protein. The dose-response curve for the plasma was parallel to that for the standard Epo preparation. The "erythroid colony-stimulating activity" in the plasma was completely additive to that in the standard Epo, and appeared to be a relatively heat-stable and acid protein with an isoelectric point lower than 5.0. These results suggest that the activity in the plasma is identical to that in the standard Epo. Stability of the plasma Epo activity was dependent on storage temperature and enhanced by adding 1% bovine serum albumin (BSA). Average Epo titers for normal adult, full-term cord, and murine plasmas, all ABC-treated and with 1% BSA added, were 192.4, 184.5, and 150.6 mU/ml, respectively. These values were much higher than those measured by the in vivo standard polycythemic mouse assay.

Animals↗
PubMed1986

Posttransfusional recovery of defective respiratory function of stored blood in dogs.

Changes in the oxygenation properties and the relevant biochemical parameters of canine blood were followed during its storage in acid-citrate-dextrose (ACD) medium (4 degrees C) and after transfusion of the stored blood. Reductions of the blood P50 (pH 7.40, PCO2 40 Torr, 37 degrees C) and 2,3-diphosphoglycerate (DPG) during storage was much slower than in human blood. Half-decay time for DPG was 21 and 5 days for canine and human blood, respectively. The DPG decay could be extensively accelerated in the presence of bisulfite in ACD. The stored and DPG-depleted red cells required a considerably long period of time for the complete posttransfusional restoration of the DPG and P50. In five dogs whose blood were exchanged by 84% in average with the stored blood of mean DPG depletion of 88%, mean extents of the DPG and P50 restoration were 74 and 89% of the normal values after 24 h. After 5 days both the parameters were within the normal ranges. The red cell extra- along with intra-cellular pH fell immediately after the transfusion, and restored to the normal level after 24 h. From these results, correlations between P50 or red cell transmembrane pH gradient at the extracellular pH of 7.40 (delta pH) and red cell DPG/hemoglobin molar ratio (chi) were derived as P50 = 10.92 chi + 14.2 (r = 0.91) or delta pH = 0.060 chi + 0.135 (r = 0.70).

Animals↗
PubMed1986

Incubation procedure effective for decreasing oxygen affinity of red cells in the dog.

Because oxygen affinity of canine red cells had been hardly reduced by the conventional procedure of incubation with inosine-pyruvate-phosphate or dihydroxyacetone-pyruvate-phosphate, incubation with acidified phosphoenolpyruvate (PEP) medium was tested for its effect on oxygen affinity. As this procedure had been shown to induce a significant increase of 2,3-diphosphoglycerate (DPG) in human red cells, it was also proved to be effective for lowering oxygen affinity of canine red cells. Incubation with 15 mM PEP in ACD medium (pH 6.0) at 37 degrees C for 30 min was the standard procedure established after critical scrutiny. The incubated blood exhibited an average increase in half-saturation pressure (P50) amounting to 7 Torr (pH 7.40, Pco2 40 Torr, 37 degrees C), with no appreciable hemolysis and little change in mean corpuscular hemoglobin concentration. Results with Dowex 1-X8 anion exchange chromatography of acid soluble phosphates from the incubated red cells suggested that PEP penetrated rapidly through the canine red cell membrane and was metabolized to DPG via the retrograde process of the Embden-Meyerhof glycolytic pathway.

2,3-Diphosphoglycerate↗
PubMed1986

Structural and functional characterization of a canine minor glycosylated hemoglobin, Hb Can AIc.

Structural and functional studies of minor glycosylated hemoglobins in non-human mammals have been very few. Therefore, we attempted further characterization of a canine glycosylated hemoglobin (tentatively designated as Hb Can AIc) which had been isolated by Bio-Rex 70 chromatography (Enoki, Y. et al. (1982) Hemoglobin 6, 143-151). After isolation of the constituent subunits by hybridization-mercuration technique, we found by peptide mapping that the structural modification was confined in amino-termini of the beta subunits in which glycosyl ketoamine linkage was also shown to be localized by thiobarbituric acid reaction. Compared with the major hemoglobin (Hb Can A0), Hb Can AIc was characterized by such functional properties as a slightly lower oxygen affinity and a markedly reduced response to the allosteric effects of carbon dioxide and organic phosphates. The anion and H+ Bohr effects were not different from those in Hb Can A0. All these facts support that this hemoglobin is a canine counterpart of Hb AIc.

Amino Acids↗
PubMed1985

In vitro erythropoietin assay based on erythroid colony formation in fetal mouse liver cell culture.

Critical studies were made on erythroid colony formation from cultured fetal mouse liver cells in an attempt to develop a simple and sensitive erythropoietin (Epo) assay procedure. The maximum colony formation was observed 24 h after plating of the cells when an evident dose-response relation was found for Epo added. The colony forming ability decreased steadily as the gestational age of the fetus advanced and was gradually lost by postnatal days 10-11. By morphological and cytochemical criteria almost all the colonies were found to be erythroid. 59Fe-labelling experiments revealed a fairly good correlation between the colony number and 59Fe incorporation into both cells and haem. Dose-response curves for plasma were parallel to the Epo standard curve. Based on these findings we developed a procedure which could measure as little as 0.4 mU of Epo without requiring 59Fe. Using this method, plasma Epo titres were determined in 16 normal and 69 anaemic subjects.

Animals↗
PubMed1985

Enhancement of erythroid differentiation in clones of human leukemic cell line K562 by fetal calf serum.

Clone cells of K562 that are able to synthesize hemoglobin spontaneously on a relatively high level were obtained by cell-cloning technique. The clone cell proliferated 25 times by day 6 in culture, and the growth rate was not affected by changing the dose of fetal calf serum (FCS) from 5% to 30%. On the other hand, the erythroid differentiation could be linearly enhanced by increasing dosage of FCS, reaching a maximum after four days in culture. The wild-type K562 cells were also slightly stimulated to synthesize hemoglobin by adding FCS (30% final concentration). The enhancing effect of 30% FCS on the erythroid differentiation in the clone cells was greater than that of 12.5 microM hemin, while in the wild-type cells the relationship was reversed. There were no effects of erythropoietin (Epo) on the hemoglobin synthesis in either the clone cells or the wild-type cells. When various kinds of sera were added to the standard culture of the clone cells, only FCS had the enhancing effect. These results suggest that spontaneous erythroid differentiation is not induced by hemin or Epo in FCS but by FCS-specific substance(s).

Adult↗
PubMed1984

Identical myoglobin is present in both skeletal and smooth muscles of chicken.

Chicken gizzard has been considered to be an exceptional organ of smooth musculature in which a myoglobin is present. Since the characterization of the gizzard myoglobin has to date, been very incomplete, we studied the structures and functions in detail. The main component, which constituted roughly 90% of the protein, isolated by chromatofocusing, was homogeneous by electrophoretic and ultracentrifugal analyses. The molecular weight was consistently 1.8 X 10(4) by equilibrium sedimentation and iron analysis, and the isoelectric point was 7.8. Spectroscopic properties of the oxy-, carboxy- and deoxy-derivatives were typical of myoglobin. The oxygenation equilibria were also typical of myoglobin, showing neither homotropic nor heterotropic allosteric interactions, and the temperature-dependence (delta H0) was estimated as -16.6 kcal/mol. All these characteristics of the gizzard myoglobin were identical with those of the protein from the skeletal muscles. The amino acid composition and peptide mapping results also concluded that identical myoglobin was present in the gizzard, skeletal and probably cardiac muscles.

Amino Acids↗
PubMed1984

Further improvement in preparation and some properties of native alpha and beta chains from canine hemoglobin treated with p-chloromercuribenzoate.

The alpha and beta chains were prepared from canine hemoglobin by a modification of the method of Bucci and Fronticelli ((1965) J. Biol. Chem. 240, PC551-552) which involved treatment of hemoglobin with an excess of p-chloromercuribenzoate (pCMB), separation of the mercurated chains by chromatography on a DE-32 column with a salt gradient at pH 8.6, and regeneration of sulfhydryl groups of the chains with 2-mercaptoethanol. The SH titer was two per heme for both the regenerated alpha and beta chains. The titer decreased to four per tetramer of hemoglobin after equimolar recombination of both chains. Measurements of the absorption spectrum and oxygen binding showed that the chains were in a native state.

Amino Acids↗
PubMed1983

Preparation of native alpha and beta subunits from canine hemoglobin.

Preparation of native alpha and beta subunits from non-primate hemoglobins has never been successful using the procedure of Bucci, E. and Fronticelli, C. ((1965) J. Biol. Chem. 240, PC551-552). We describe a method for isolating the constituent subunits from canine hemoglobin. Human-canine hybrid hemoglobins (alpha 2Can beta 2A and alpha 2A beta 2Can) were prepared by acid hybridization techniques and DEAE-Sephadex chromatography. The hybrids were then reacted with an excess of p-chloromercuribenzoate under slightly acid conditions and the resultant alpha Can and beta Can subunits were isolated by either anion- or cation-exchange chromatography. Identifications of the subunits were made by gel electrophoresis and amino acid analysis. After removal of the bound mercurials with beta-mercaptoethanol, both subunits exhibited two reactive sulfhydryl groups per chain and were found to be fully in the native form, as judged by spectroscopy. By ultracentrifugal analysis, the alpha subunit was shown to be in a dimer-monomer equilibrium while the beta subunit was largely in a tetrameric form.

Amino Acids↗
PubMed1983

A simple microtonometric method for whole blood oxygen dissociation curve and a critical evaluation of the "single point" procedure for blood P50.

We devised a rapid and simple method to obtain oxygen dissociation curve (ODC) for a small amount of blood with simple equipment. This system achieved the gas-blood equilibrium within 3 min. Oxygen saturation of the equilibrated blood was measured spectrophotometrically while the pH, PCO2, and PO2 was measured with a Radiometer blood gas analyzer system. Whole procedures to construct ODC from the 6 point measurements could be performed within 1 hr. The standard ODC for 25 normal Japanese adults showed a mean P50 of 27.6 +/- 1.1 Torr (pH 7.40, PCO2 40 Torr, 37 degrees C), a slightly higher value than previously reported. The discrepancy, however, can be eliminated when corrected for a slightly lower SO2 by the present procedure. The standard curves for the adult blood at pH 7.20 and 7.60 and for the cord blood at pH 7.40 were also described. The "single point" procedure, a much quicker approach to measure the P50 (Aberman et al., 1975), was scrutinized by comparing with the "whole curve" method. The P50's by the two methods were not significantly different, mean +/- S.D. of the differences being 0.4 +/- 2.5 Torr (n = 126) for the adult blood at pH 7.40, PCO2 40 Torr and 37 degrees C. Similar results were obtained for the adult blood at pH 7.20 and 7.60 and for the cord blood at 7.40. We concluded that the "single point" method was sufficiently accurate and reliable.

Adult↗