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Y Enoki

Publications and source records attributed to Y Enoki.

At least 19 recordsLinked to original sources
PubMed1996

Mixed disulphide formation in myoglobin of mouse (Mus musculus).

The myoglobin, isolated from murine skeletal muscles by chromatofocusing, showed the three components, one major and two minor, with different electrophoretic mobilities. The major component with the isoelectric point (pI) of 7.55 had one reactive SH/mole, while the others with pI of 7.32 and 7.16 showed none, which could be rendered fully reactive by treating the proteins with beta-mercaptoethanol. The three components were the same in their molecular weight (18 kDa), amino-acid composition with one Cys residue and oxygenation properties. By a sensitive high-performance liquid chromatography method, the occurrence of cysteine or glutathione mixed disulphide was verified in the two minor components. We conclude from these results and incubation experiments with low-molecular-weight thiols that the two minors were derived from the major by a mixed disulphide formation with either cysteine or glutathione of the cysteinyl SH at the 66th sequence.

Animals↗
PubMed1996

Flow-dependent influence of high-O2-affinity erythrocytes on peak VO2 in exercising muscle in situ.

To evaluate the influence of a high-O2 affinity of the erythrocyte and of flow rate on muscle's ability to extract O2 and develop force, we perfused dog gastrocnemius contracting isometrically at 4 Hz with normal-O2-affinity perfusate or high-O2-affinity perfusate at high and moderate flows (200 and 100 ml . min-1 . 100g-1, respectively). High-O2-affinity perfusate was prepared by incubating human citrate-phosphate-dextrose-stored erythrocytes with buffered saline containing cyanate (4 degrees C, 18 h) and normal-affinity perfusate by storing 2,3-diphosphoglycerate-rejuvenated erythrocytes in the same solution without cyanate. PO2 when blood is half oxygenated was 30.6 Torr for normal perfusate and 18.1 Torr for high-affinity perfusate. During 4-Hz stimulation, the tension developed by the muscle increased incrementally (positive staircase) to reach a peak value after 1.2-1.6 min for the normal perfusate and 0.6-0.7 min for the high-affinity perfusate (P < 0.05). The rate of decline during the early fatigue (measured from the onset of tension decline to 3 min) with high-affinity perfusate was significantly faster than it was with normal perfusate (P < 0.05). These findings suggest that both the staircase effect and the early fatigue are related to O2 availability, which is restricted when erythrocytes have a high O2 affinity. The peak O2 uptake values measured at 3 and 5 min were significantly lower (by 14-24%) with high-affinity perfusate than with normal perfusate at a given level of O2 delivery (arterial O2 content x flow) (P < 0.05). PO2 of venous effluent was proportionally related to peak O2 uptake. The present results indicate that neither blood flow nor O2 delivery is the sole determinant of the muscle's ability to extract O2.

Animals↗
PubMed1995

Oxygen affinities (P50) of myoglobins from four vertebrate species (Canis familiaris, Rattus norvegicus, Mus musculus and Gallus domesticus) as determined by a kinetic and an equilibrium method.

Rate constants of the reaction with oxygen of myoglobins from four vertebrate species (Canis familiaris, Rattus norvegicus, Mus musculus and Gallus domesticus) and the isolated alpha A and beta A chains of human adult hemoglobin (HbA) were determined by the stopped-flow-spectrophotomeric method. Half-saturation oxygen pressure (P50) of the proteins calculated from the rate constants, assuming a simple bimolecular reaction model, agreed very well with those directly determined by oxygen equilibria. The proteins used were freshly prepared, and fully characterized by electrophoretic and ultracentrifugal analyses. Sulphydryl groups in the Hb chains were ascertained to be completely regenerated.

Animals↗
PubMed1995

Correlation between a sandwich ELISA and an in-vitro bioassay for erythropoietin in human plasma.

A sandwich-type enzyme-linked immunosorbent assay (ELISA) for human erythropoietin (EPO) using two anti-EPO monoclonal antibodies has been compared with an in-vitro EPO bioassay based on CFU-E colony formation in fetal mouse liver cell cultures. In normal subjects and non-uraemic anaemic patients the plasma EPO values estimated with the ELISA correlated well with those by the bioassay, and also inversely with the values of blood Hb, PCV and RBC counts. Dose-response curves for plasma and standard recombinant human EPO in the ELISA were parallel to each other. These results further confirm the validity for the ELISA in measuring circulating human EPO.

Adult↗
PubMed1994

Erythropoietin response to acute hypobaric or anaemic hypoxia in gentamicin-administered rats.

In an attempt to assess the erythropoietin (Epo) production site(s) in rat kidney, Epo response to hypoxia and renal histopathological changes were studied in rats administered with graded doses of gentamicin. Male Sprague-Dawley rats of 9 to 11 weeks old were used. Following a 14-day subcutaneous administration (67.5 or 33.8 mg kg-1 day-1) of gentamicin, a nephrotoxic aminoglycoside, selective proximal tubular lesions were produced. These gentamicin-administered rats were compared with normal rats with respect to Epo response to hypoxia. Two different kinds of hypoxic load, either 0.35 atm hypobaric hypoxia (PIO2 = 46 torr) or acute anaemia (Ht: 29.3 +/- 0.2% and [Hb]: 9.7 +/- 0.3 g dl-1) by withdrawing of blood corresponding to 1-2% of body weight was used. During the hypoxic period of up to 48 h, the peak renal venous plasma Epo titres of 3.1 +/- 0.6 and 4.3 +/- 0.6 U ml-1 was observed at the 6th h in normal hypobaric hypoxic and anaemic rats, compared with the prehypoxic value of 0.7 +/- 0.1 U ml-1. The Epo titres then declined gradually. In the rats which were administered gentamicin, Epo response pattern was the same as that observed in the normal rats, but the peak value decreased significantly to 0.8 +/- 0.3 and 1.1 +/- 0.4 U ml-1 in hypoxic and anaemic rats (P < 0.05). Histological examination revealed the selective damage to renal proximal convoluted tubules. The Epo response was reduced by the tissue damages, and restoration of the gentamicin-induced tissue injury was accompanied with restored Epo response to hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia↗
PubMed1994

High affinity of blood for oxygen reduces oxygen uptake in contracting canine gracilis muscle.

To clarify the influence of blood flow with high-oxygen (O2)-affinity blood on oxygen consumption (VO2) in submaximally exercising skeletal muscle, we perfused the isolated dog gracilis (n = 8) contracting under 1 Hz stimulation alternatively with normal and high-O2-affinity blood, with a constant arterial O2 content (Ca,O2) and varying perfusion rates. The average P50 (oxygen partial pressure (PO2) for half-saturation at pH 7.40, PCO2 of 40 mmHg at 37 degrees C) of the high-O2-affinity blood prepared by carbamylation was 15.5 mmHg, and that of the normal blood 33.7 mmHg. With normal blood perfusion, the average VO2 above 6 ml min-1 (100 g)-1 of O2 delivery (Ca,O2 x flow) was 4.38 ml min-1 (100 g)-1 (range 4.17-4.68 ml min-1 (100 g)-1, and VO2 at the O2 delivery range of 6-5 and 4-2.5 ml min-1 (100 g)-1 decreased to 3.96 and 2.43 ml min-1 (100 g)-1, respectively. The PO2 of venous effluent (Pv,O2) at the O2 delivery of 6 ml min-1 (100 g)-1 was 33 mmHg. With low-P50 blood perfusion, VO2 was significantly less than with normal blood, both below the O2 delivery level of 6 ml min-1 (100 g)-1 and above it, even in the fairly high O2 delivery range of 8.5-12 ml min-1 (100 g)-1 (P < 0.05). Thus, high blood flow did not compensate for the reduced VO2 caused by high-O2-affinity blood. At values of Pv,O2 less than 33 mmHg, VO2 with low-P50 blood was not significantly different from that with normal blood (P > 0.05). The reduced VO2 in submaximally exercising skeletal muscle might be due to a slower O2 dissociation from the high-O2-affinity red cells and to a limited O2 diffusion resulting from the lower Pv,O2 value (which reflects mean end-capillary PO2).

Animals↗
PubMed1993

High blood O2 affinity and relationship of O2 uptake and delivery in resting muscle.

To clarify the effects of high oxygen (O2) affinity of blood under stagnant hypoxic conditions, we studied the relationship between VO2 and O2 delivery (CaO2.flow) in isolated dog gracilis muscles perfused with low and normal P50 blood. The high affinity blood was prepared by either short-term incubation (P50 = 24.8 +/- 1.0 Torr) or long-term refrigerated storage (P50 = 19.5 +/- 1.5 Torr) with sodium cyanate. VO2 of the resting muscle was independent of O2 delivery above a critical level (0.45 ml.min-1.100 g-1), but was dependent on it below this level. The critical O2 delivery (0.45 ml.min-1.100 g-1), the maximal O2 extraction ratio (0.62), and the plateau VO2 (0.28 ml.min-1.100 g-1) in the present perfusions with low P50 blood were similar to those with normal blood. "Critical PvO2" (i.e. PvO2 at the critical O2 delivery) was 33 Torr in the perfusions with normal blood but only 19 Torr in the low P50 perfusions. The perfusion pressure-blood flow relationship was not influenced by the affinity change. These results suggest that the true critical PvO2 in resting muscle is lower than 19 Torr and hence that the decrease in VO2 in resting skeletal muscle under stagnant flow conditions is not caused by a decrease in PO2 driving pressure, but by a decrease in the surface area available for diffusion due to a closure of capillaries induced by the low perfusion pressure.

Animals↗
PubMed1993

Random process of metastasis and generation of heterogeneity in a mouse sarcoma line.

The process of metastasis was analyzed in 505-05-01 cells, an established line of a methyl-cholanthrene-induced mouse sarcoma, by tagging the cells with the pSV2neo plasmid. A dominant clone was identified which, upon transplantation together with other clones, overgrew tumors in the kidney capsule. However, when this clone was transplanted in a mouse collaterally with recessive clones, both clones grew at the same rate and metastasized to the lung at an equal frequency. This suggests that the process of metastasis in this particular sarcoma line is stochastic, the dominant population having a better chance to colonize to the lung. The dominant neomycin-resistant clone was transfected with another marker plasmid, pY3, which confers resistance to hygromycin. Results of mixed inoculation of 9 independently isolated clones revealed the hierarchy of dominance among clones. This indicated the existence of heterogeneity within the parental clone. Upon mixed inoculation with hygromycin-resistant clones, the parental clone overgrew in the tumors. This indicated that some clone had changed its phenotype to become less aggressive. Thus, the direction of phenotypic drift in vitro seems to be random in terms of behavior in vivo.

Animals↗
PubMed1992

Improved microbioassay for plasma erythropoietin based on CFU-E colony formation.

We examined the conditions necessary for performing a reliable erythropoietin (EPO) assay based on CFU-E colony formation in fetal mouse liver cell (FMLC) microcultures using 96-well microtiter plates. Both linearity of colony numbers with the number of cells plated and comparison among the colony ratios at various densities of seeding cells indicated that the colonies originated from a single progenitor cell when 7500 or fewer cells were plated into individual microtiter wells. About a twofold CFU-E enrichment in 12- to 13-day FMLC was achieved by Ficoll-Paque centrifugation. Plasma treated with acid-boiling stimulated the colony formation most and contained no colony inhibitor. Dose-response curve for the plasma was parallel to the EPO standard curve. The "erythroid colony-stimulating activity" in the plasma was additive to that in the standard EPO, and was completely neutralized by a monoclonal antibody against recombinant human EPO. Using the assay procedure thus established, plasma EPO titer was determined in normal subjects, in patients with nonuremic anemia and polycythemia vera, and in dialysis patients with chronic renal failure. The use of different preparations of standard EPO resulted in a significant difference in the titers because their dose-response curves differed from one another. An inverse relationship was found between EPO titers and hemoglobin concentrations in the nonuremic anemic patients, but not in the dialysis patients with about one half the normal EPO level.

Anemia↗
PubMed1992

Relationships between %Hb F or %G gamma and the haplotypes in the beta-globin gene cluster in the normal adult Japanese and Korean populations.

Haplotypes or subhaplotypes in the beta-globin gene cluster were examined in 31 normal Japanese and 21 Korean families. Major haplotypes were VII, V, and I, which shared a common subhaplotype [+----], and occurred in 70% of the Japanese and 68% of the Koreans. Three haploypes which shared a common subhaplotype [-+-++], bearing the XmnI site 5' to the G gamma-globin gene, occurred in 13% of the Japanese and 7.3% of the Koreans. One subhaplotype [-++-+], which is closely linked to the A gamma T-globin gene, had an incidence of 6.6% in the Japanese and 20% in the Koreans. Rare subhaplotypes [---++], and [- +] which has been observed mainly in Melanesians and Polynesians, and a very rare subhaplotype [-----] were observed. The present study suggests that high or low G gamma-globin chain production is closely related to subhaplotypes [-+-++] and [+----], respectively, among the normal adult population.

Adult↗
PubMed1992

The XmnI site 5' to the G gamma-globin gene polymorphism and its relationship to %Hb F and %G gamma in normal Japanese and Korean adults.

The ratio of fetal hemoglobin to total hemoglobin (%Hb F), the ratio of G gamma to total gamma globin (%G gamma), and the polymorphism of the XmnI site at -158 base pairs from the cap site of the G gamma-globin gene were examined in normal unrelated Japanese (n = 113) and Korean (n = 44) adults. The frequency of the presence of the XmnI site was 0.15 in the Japanese and 0.16 in the Korean population. There were statistically significant differences in the %G gamma values of the Japanese between those +/+ and those +/- or -/- at the XmnI site (p less than 0.01). The Korean %G gamma values showed a statistically significant difference (p less than 0.01) between those +/- and those -/-. The presence of the XmnI site was significantly associated with the elevation of G gamma-globin chain synthesis, but this relationship was not necessarily absolute. The absence of the XmnI site in an adult with a gamma-globin gene triplication (G gamma AG gamma A gamma/G gamma A gamma) more or less reduced the level of G gamma-globin chain synthesis, but the presence of the XmnI site in an adult with a gamma-globin gene deletion (GA gamma/G gamma A gamma) had no effects on the proportion of the two gamma-globin chains.

Adult↗
PubMed1992

Neutralization and immunoaffinity chromatography of erythroid colony-stimulating activity in mouse plasma by an anti-erythropoietin monoclonal antibody.

A relationship between erythropoietin (EPO) and erythroid colony-stimulating activity (ECSA) in mouse plasma was examined in fetal mouse liver cell (FMLC) cultures using a monoclonal antibody (MoAb) R2 raised against recombinant human EPO. Most of the ECSA in plasma from normal, anemic, and hypoxic mice was neutralized by MoAb. This neutralization could be reversed by addition of excess of anemic plasma or by preincubation of MoAb with goat anti-mouse IgG antibody. Most of the plasma ECSA was bound to an immunoadsorbent column containing the immobilized MoAb, and the retained ECSA was completely neutralized by MoAb. The plasma ECSA and standard EPO showed parallel dose-response curves and additive effect on CFU-E stimulation. Based on these findings, we conclude that mouse plasma ECSA detected by CFU-E assay using FMLCs is mainly due to EPO.

Anemia↗
PubMed1992

[Case study of interleukin-1 beta, tumor necrosis factor alpha and interleukin-6 production peripheral blood monocytes in patients with diabetes mellitus complicated by pulmonary tuberculosis].

Patients with diabetes mellitus (DM) show an increased susceptibility to bacterial infections due to the presence of neutrophil dysfunction. Susceptibility to tuberculosis has also been reported in such patients, however, the reason remains unclear. This study measured the production of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) by the peripheral monocytes of patients diagnosed with pulmonary tuberculosis accompanied by DM (TB+DM) and patients without DM complications (TB) using age-matched, healthy control subjects for comparison. Also examined was the relationship between cytokine production and DM control. The results were as follows: (1) The production of IL-1 beta, TNF alpha and IL-6 in TB patients was significantly higher than that observed in the healthy control subjects. (2) The production of IL-1 beta, TNF alpha and IL-6 in TB+DM patients was significantly lower than that observed in the TB patients. (3) The production of IL-1 beta and TNF alpha in TB+DM patients with poor control was significantly lower than that observed in the patients with good control. (4) The TNF alpha production had a significant inverse correlation to HbA1c in the TB+DM patients. This study demonstrated that the production of cytokines is impaired in TB+DM patients and suggests a close correlation between tuberculosis immunity and DM.

Adult↗
PubMed1992

Developmental changes in plasma erythroid colony-stimulating activity in mice: cyclic erythropoiesis associated with rapid growth.

To establish a role of erythropoietin (Epo) in regulation of fetal and neonatal erythropoiesis, plasma erythroid colony-stimulating activity (ECSA) in developing mice was measured by an erythroid colony-forming assay using fetal mouse liver cells. The ECSA in fetal and neonatal plasmas showed dose-response curves parallel to standard Epo curve and additive effects with standard Epo on the colony formation. Most of the plasma ECSA was neutralized by an anti-Epo monoclonal antibody. These results suggest that the plasma ECSA detected by the present bioassay is predominantly due to Epo. On day 12-14 of gestation, the plasma ECSA levels were at the highest values; thereafter the levels oscillated up to the age of 4 weeks. The packed cell volume (PCV) also oscillated, but with the reverse phase. Oscillation in PCV was associated with the growth. There was an inverse relationship between plasma ECSA and PCV levels throughout the prenatal and early postnatal periods. The results indicate that erythropoiesis in fetal and neonatal mice is regulated mainly on the basis of PCV-ECSA feedback control mechanism.

Animals↗
PubMed1991

Postnatal transition of gamma-globin gene expression in normal Japanese population.

Temporal course of postnatal changes in the gamma isoform composition of human fetal haemoglobin (HbF) was studied in 259 cord, 272 infantile and 216 adult Japanese blood samples. Reversed phase high-performance liquid chromatography was used for determination of the three isoforms of the gamma chain (A gamma T, A gamma I and G gamma), and the adult samples, usually with less than 1% of Hb F, were enriched for Hb F by an alkali denaturation-salting out procedure. The results show that the G gamma gene expression, kept at a higher and strictly-controlled level in the neonatal period, undergoes a gradual change during 1 year, beginning 3-4 months after birth, to the adult stage which is characterized by a generally lower and loosely-controlled expression of the gene. Further change seems to occur after 1 year, settling to the final adult level. The A gamma T gene frequency is estimated as 0.139 in the present Japanese adult population, and is essentially identical to the value for the newborns in the same population (0.141).

Adult↗
PubMed1991

Oxygen consumption in resting dog gracilis muscle perfused at varying oxygen delivery.

The different response of O2 uptake (VO2) of resting skeletal muscle to the changes in blood flow has been thought to reflect a species difference. To scrutinize this notion, we investigated the relation between O2 delivery (arterial O2 content multiplied by blood flow) and VO2 in isolated dog gracilis muscle perfused solely with normal hematocrit (Ht) blood (n = 9), or alternately with normal and low Ht blood (n = 6), or alternately with normal and high Ht blood (n = 3) at varying perfusion rates. Eleven out of the 18 preparations showed an autoregulation of blood flow, and the others did not. But, in all preparations, the VO2 was delivery-independent above a critical O2 delivery (0.45 ml/(min.100 g muscle)) and showed the constant VO2 of 0.30 ml/(min.100 g), while below the critical level it turned out to be delivery-dependent. The maximal extraction ratio was 0.67. The same relationship was found with the low and high Ht perfusion. The pattern observed in dog gracilis muscle was essentially the same as that in rat gracilis muscle (KOLAR and JANSKY, 1984).

Animals↗