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Biomedical subjects

H D Kim

Publications and source records attributed to H D Kim.

At least 145 records · Page 8Linked to original sources
PubMed1980

(Ca2+ + Mg2+)-ATPase of density-separated human red cells. Effects of calcium and a soluble cytoplasmic activator (calmodulin).

The effect of calcium and a soluble cytoplasmic activator on (Ca2+ + Mg2+)-ATPase of density-separated human red cells was investigated. At all calcium concentrations tested, dense (old) lysed cells and their isolated membranes displayed lower activities as compared to the light (young) cells and their membranes. Isolated membranes from all density red cell fractions showed two distinct (Ca2+ + Mg2+)-ATPase activities; one at low calcium and another at moderate calcium concentrations. At high calcium concentration, (Ca2+ + Mg2+)-ATPase activity of isolated membranes was low in all cell fractions. In contrast to the isolated membranes, lysed cells from all density fractions had a maximum (ca2+ + Mg2+)-ATPase activity only at a low concentration of calcium, while moderate and high calcium concentrations produced low activity. Upon isolation of membranes, a substantial loss of (Ca2+ + Mg2+)-ATPase activity took place from all density cell fractions. Upon membrane isolation, the relative loss of (Ca2+ + Mg2+)-ATPase activity at low Ca2+ concentration was greater in older cells. The extent of stimulation of (Ca2+ + Mg2+)-ATPase by the activator at low calcium concentration was 3-4-fold greater in older cell membranes than in the young ones. These data suggest that the lower (Ca2+ + Mg2+)-ATPase activity in old cells could be accounted for by a selective loss of (Ca2+ + Mg2+)-ATPase activity at low Ca2+ concentration presumably due to reduced affinity of old cell membranes to activator protein.

Adult↗
PubMed1980

A symbiotic relationship of energy metabolism between a 'non-glycolytic' mammalian red cell and the liver.

The red cell of newborn pig loses the ability to carry out glycolysis within a month after birth. The metabolic energy source for this 'non-glycolytic' mammalian red cell is unknown. Hepatectomy of an adult pig results in the loss of red cell ATP with a characteristic half-time of 7--8 h which is identical to the rate with which ATP disappears in the pig cells under in vitro substrate-free incubation. Exposure of pig red cells with either normal or depleted levels of ATP to isolated hepatocytes causes a net synthesis of red cell ATP during a 12 h incubation. These findings suggest that a symbiotic relationship of energy metabolism may exist between the red cell and the liver of the pig.

Adenosine Triphosphate↗
PubMed1980

A patient with apparent idiopathic A-megakaryocytic thrombocytopenia.

A 71-year-old woman developed life-threatening thrombocytopenia which resolved (probably spontaneously), recurred, and then again resolved. The thrombocytopenia was characterized by selective aphasia of megakaryocytes, near-normal platelet survival, and very slow recovery. No underlying disorder nor any drug could be incriminated, so we must assume this patient suffered from an idiopathic and very rare form of thrombocytopenia.

Aged↗
PubMed1980

LK sheep reticulocytosis: effect of anti-L on K influx and in vitro maturation.

After massive hemorrhage, adult sheep with genotypically low potassium (LK) red cells temporarily produce high potassium (HK) cells with ouabain-sensitive K+ pump fluxes equivalent to mature HK red cells. In light of recent reports of different red cell volume populations accompanying the HK-LK transition also occurring in newborn LK sheep and the unresolved controversy over the effect of anti-L on K+ transport in these immature red cells, we have reexamined the K+ transport changes and the effect of anti-L in the newly formed HK cells at various times after anemic stress and under in vitro conditions. We found that approximately 7 d after bleeding, maximum reticulocytosis occurred in the peripheral blood. After separation by density centrifugation, the top 10% cell fraction contained 100% reticulocytes, with a mean cell volume 2.5 times larger than that of mature erythrocytes. These immature red cells were of HK type, and their K+ pump and leak fluxes were 30 and 10 times higher, respectively, than those found in mature LK cells. The new cells may possess HK- and LK-type pumps because K+ pump influx was significantly stimulated by anti-L. When separated by density centrifugation on days 9, 17, and 23 after bleeding, some of the cells apparently maintained their large size while gaining higher density. Large cells from day 9, kept in vitro for 22 h, showed anti-L-sensitive K+ pump and leak fluxes that declined within hours, paralleling the behavior of these cells in vivo, whereas cellular K+ levels changed much less. It is concluded that the newly formed red cells may belong to a stress-induced macrocytic cell population that does not acquire all of the characteristics of adult LK cells.

Animals↗
PubMed1980

Factors influencing osmotic fragility of red blood cells in Duchenne muscular dystrophy.

Factors affecting osmotic fragility were studied in red blood cells of patients with Duchenne muscular dystrophy. The mean osmotic fragility (MOF), operationally defined as the NaCl concentration for 50% hemolysis, was found to be higher by 3.63 +/- 0.51 mM in Duchenne cells than in normal cells having an MOF of 60.1 +/- 0.5 mM NaCl buffered with 10 mM sodium phosphate at pH 7.0. However, about 20% of Duchenne patients had red cells indistinguishable from their age- and sex-matched controls. Temperature, pH, preincubation in plasma, and proteolytic digestion all affected Duchenne and normal cells to the same extent. However, after salt loss, induced either by preincubation in isotonic nonelectrolyte solutions or by exposure to ionophore A23187, Duchenne cells showed a greater change in MOF. Osmotic fragility of Duchenne cells was increased even in younger blood cells, suggesting that the membrane was abnormal in the early stages of red cell maturation.

Adolescent↗
PubMed1979

Cow red blood cells. III. Postnatal adaptation of energy metabolism in the calf red blood cells.

1. The change in energy metabolism of red blood cells from the newborn calf to adult cow was examined utilizing a number of metabolic substrates including glyceraldehyde, dihydroxyacetone, ribose, glucose, adenosine and inosine. 2. All of these substrates are utilizes by the newborn calf cells to a varying degree. With glyceraldehyde, dihydroxyacetone or glucose as a substrate, lactate is formed at a rate of 2-3 mumol/ml cells per h. As in other species, ribose utilization depends on substrate concentration, with an optimum of 3 mM ribose yielding lactate 1-1.5 mumol/ml cells per h in the calf cells. 3. In sharp contrast, adult cow red blood cells lost the bulk of the postnatal metabolic substrate affinities except for glyceraldehyde and glucose which are consumed at less than half of the rate at birth. 4. While the transition of the metabolic properties from the newborn to the adult state takes place within 2 to 3 months after birth, the red blood cells produced shortly after birth have already assumed the metabolic machinery characteristic to the adult cells. 5. Even though adenosine in itself is a poor substrate in producing lactate, a net synthesis of ATP from adenosine can take place in both calf and cow cells provided that an alternate carbon source such as glyceraldehyde, dihydroxyacetone or glucose is given. 6. Of the test substrates, glucose is the only substrate for the adult cow cells exhibiting a greater than 50% increase in utilization by exogenously added adenine. By contrast, the calf cell is affected to a much lesser extent. The possible in vivo regulatory metabolic role of certain purine and pyrimidine compounds unique to the adult stage of this species is discussed.

Adenosine↗
PubMed1979

Effects of low electrolyte media on salt loss and hemolysis of mammalian red blood cells.

Cation loss and hemolysis of various mammalian red cells suspended in isotonic non-electrolyte media were investigated. Sucrose buffered with 10 mM Tris-Hepes, pH 7.4 was used as the non-permeable non-electrolyte. Mammals from which the red cells were derived include the human, guinea pig, rat, rabbit, newborn calf, newborn piglet and pig, all of which contain K as the predominant cation species (HK type) and the dog, cat, sheep and cow, all of which possess Na as the predominant cation species (LK type). Of HK cells, a rapid efflux of K takes place from humans, rats and guinea pigs. Of LK type cells, the dog and cat exhibit an augmented membrane permeability to Na. The governing factors which influence cation permeability are the change in pH, temperature, and ionic strength. In response to increase in pH, the red cells of humans, dogs and cats become more permeable to cations, whereas the red cells of rat and rabbit are unaffected. In response to increase in temperature, HK type cells exhibit augmented K efflux, while the Na loss from the dog and cat cells manifest a well-defined maximum at near 37 degrees C. In all cases, a small substitution of sucrose by an equal number of osmoles of salts results in a dramatic decrease in cation loss. By contrast, the red cells of the rabbit, newborn calf, adult cow, newborn piglet, adult pig and sheep display no discernible increase in ion-permeability under the conditions alluded to above. In some species including the newborn calf, dog, and cat, an extensive hemolysis occurs usually within an hour in isotonic buffered sucrose solution. The osmolarity of sucrose solution affects these cells differently in that as the osmolarity increases from 200--500 mM, hemolytic rates of the calf and dog reach a saturation near 300 mM sucrose, whereas the hemolytic rate of the cat decreases progressively. Common features pertaining to this hemolysis are (1) the intracellular alkalinization process; and (2) the diminution of the cell volume which take place prior to and onset of hemolysis. SITS, a potent anion transport inhibitor, completely protects the cells from hemolysis by inhibiting chloride flux and the concomitant rise in intracellular pH.

Animals↗
PubMed1979

A syndrome resembling idiopathic thrombocytopenic purpura in 10 patients with diverse forms of cancer.

Ten patients with diverse forms of carcinoma (six patients) and of cancer in the lymphoid system (four patients) presented with or subsequently had a syndrome resembling idiopathic thrombocytopenic purpura (ITP). These patients were older than patients who had ITP alone. ITP was coincident with a diagnosis of cancer (three patients), preceded a diagnosis of cancer (three patients) or followed a diagnosis of cancer (four patients). No patients responded to steroid therapy permanently. Therefore, the course of our patients was fairly typical of ITP in the adult. Since we found nine patients with cancer in a survey of 52 consecutive patients with ITP in the adult population admitted to one hospital, this diagnosis may be missed with some frequency; the development of thrombocytopenia being attributed to other causes.

Adolescent↗
PubMed1979

Cow red blood cells. I. Effect of purines, pyrimidines, and nucleosides in bovine red cell glycolysis.

Cow red cells, under in vitro incubation conditions, exhibit a comparatively low glycolytic rate of 0.56 +/- 0.05 micromol/(ml cells.h), with a ratio of lactate formed to glucose consumed of 1.58. It has been found that this low glycolytic rate can be stimulated 50--60% above the basal level in the presence of a variety of purine and pyrimidine compounds including adenosine, inosine, adenine, hypoxanthine, xanthine, and uracil. In contrast, calf red cells, which have a much higher glycolytic rate, display no discernible response to these agents. In attempts to elucidate the mechanism by which this stimulation takes place, both glucose transport and glycolytic enzyme activities were determined in the presence of these stimulators. Glucose influx in cow red cells, measured using the glucose analog 3-O-methyl-glucose, exhibits both a low Km of 117 microM and a Vmax of 0.38 micromol/(ml cells.min), and is unaltered in the presence of adenosine. On the other hand, hexokinase, which in normal hemolysates of cow red cells has an activity of 0.49 +/- 0.03 micromol/(g Hb.min). was found to be stimulated to 0.73 micromol/(g Hb.min) in the presence of adenine. Both pyruvate kinase and phosphofructokinase were unaffected by this compound. These data suggest that certain purines and pyrimidine compounds may exert their stimulatory effect on hexokinase activity, resulting in an augmentation of cow red cell glycolysis.

Aging↗
PubMed1979

Cow red blood cells. II. Stimulation of bovine red cell glycolysis by plasma.

Cow red cell glycolysis, which can be stimulated by a variety of purines and pyrimidines, was also found to be elevated by its own plasma. Dialyzed or charcoal-treated plasma could no longer stimulate glycolysis, suggesting that the stimulating factors may be purines or pyrimidines. Determination of purines or pyrimidines in plasma revealed the presence of xanthine (0.31 muM), hypoxanthine (0.60 muM), and adenosine (0.05 muM), as well as unknown compounds. A physiologic level of hypoxanthine, with or without xanthine and adenosine approximating their concentrations in plasma, resulted in the stimulation of cow red cell glycolytic rate by 16% (P less than 0.01). These findings suggest that plasma-borne purines may act on cow red cells in concert with as yet unidentified factors. Moreover, exchanging calf and cow plasmas produced no stimulatory effect on either calf or cow red cell glycolysis, suggesting that a) calf red cells lack some of the cellular components that respond to this stimulator and, b) only cow plasma contains this specific stimulator. In other species, including dog, cat, rabbit, rat, guinea pig, and human, stimulation of glycolysis by plasma was not observed.

Aging↗
PubMed1977

Pig reticulocytes. III. Glucose permeability in naturally occurring reticulocytes and red cells from newborn piglets.

The loss of facilitated glucose transport of red cells occurring in the newborn pig was monitored in 11 density-separated cells from birth to a 4 wk of age. At birth there was a threefold increase in glucose permeability from the lightest cells to the most dense, suggesting that cells having progressively less glucose permeability are released into the circulation as gestation proceeds. Because of extraordinary stimulation of erythropoietic activity, the uppermost top fraction constituting 2-3 percent of the total cells is composed purely of reticulocytes in the growing animal. The glucose permeability of these reticulocytes which at birth has a slow but significant rate of 3.7 mumol/ml cell x min at 25 degrees C is rapidly decreased within 3-4 days to the level of reticulocytes produced in the adult in response to phenylhydrazine assault. Moreover, reticulocytes themselves discard their membrane permeability to glucose in the course of maturation to red cells. Thus, even though reticulocytes at birth are permeable to glucose, they will become red cells practically impervious to glucose within a few days. These findings suggest that the transition from a glucose- permeable fetal state to a glucose-impermeable postnatal state is brought about by two mechanisms: (a) dilution of fetal cells by glucose-impervious cells produced coincidentally with or shortly after birth; and (b) elimination of fetal cells, which have a shorter half-life, from the circulation.

Aging↗
PubMed1977

Preferential hemolysis of postnatal calf red cells induced by internal alkalinization.

Red blood cells from neonatal calves, but not from adult cows, rapidly hemolyze in buffered 300 mM solutions of a variety of nonelectrolytes and amino acids. Of these compounds, sucrose is chosen to elucidate the mechanism by which this preferential hemolysis takes place. As in other mammalian red cells, both calf and cow cells are found to be impermeable to sucrose and, in an isosmolar sucrose solution, to undergo volume shrinkage caused by the net loss of chloride ions with concomitant increase in intracellular pH. To test the potential role of intracellular pH change associated with chloride loss in promoting hemolysis, intracellular pH was altered by: (a) a direct addition of fixed acid or base to sucrose solution; (b) the removal of dissolved CO(2) from sucrose solution; and (c) the addition of cells to isotonic NaHCO(3) solution in the absence of sucrose. In all cases, only calf and not cow cells underwent hemolysis. Moreover, 4-acetamido-4'-isothiocyano-2,2'-stilbene disulfonic acid, a potent anion transport inhibitor, completely protected calf cells from hemolysis and caused a nearly total inhibition of both chloride loss and intracellular alkalinization. Furthermore, the hemolytic process is closely related to the integrity of a membrane protein, the band 3 protein, which can be cleaved to varying degrees by the combined treatment of pronase and lipase. Hemolysis is progressively inhibited as the band 3 protein undergoes proteolysis, until a total inhibition of hemolysis takes place when almost all of the band 3 protein is digested into smaller protein components with a mol wt of 65,000 and 35,000 daltons. These results suggest that the intracellular alkalinization process leading to a structural instability of the membrane band 3 protein is responsible for this calf cell hemolysis.

Animals↗