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Biomedical subjects

M K Song

Publications and source records attributed to M K Song.

At least 73 records · Page 4Linked to original sources
PubMed1985

Effect of oral administration of arachidonic acid on prostaglandin and zinc metabolism in plasma and small intestine of the rat.

The effect of different doses of arachidonic acid (AA) on the intestinal zinc transport rate and on the plasma and intestinal PGE2, PGF2 alpha and 6-keto-PGF1 alpha levels in rats were measured to determine whether the metabolism of AA is involved in the zinc transport mechanism. Twenty-four rats were divided into 4 groups of 6 rats. Each rat received either 1.0 ml of distilled water, 0.5 mg, 1.0 mg or 1.5 mg/ml of AA intraduodenally at 24 and 4 hours before sacrifice. One hour before sacrifice, each rat also received 10 micrograms of 65Zn intraduodenally. The zinc transport rate decreased in comparison to controls when 0.5 mg of AA was given to the rats, but increased when 1.0 mg or 1.5 mg of AA was given. The levels of PGE2, PGF2 alpha and 6-keto-PGF1 alpha (PGI2 metabolite) in the intestinal mucosa all decreased in proportion to the amount of AA given. However, in the plasma, only PGF2 alpha levels decreased while PGE2 and 6-keto-PGF1 alpha levels showed no change compared to controls. When rats were given 1.5 mg of AA without oral administration of 65Zn, plasma PGE2 levels increased while PGF2 alpha levels decreased. The results suggest that AA metabolism influences the zinc transport mechanism by modulating the relative levels of PGE2, PGF2 alpha and PGI2 in plasma and small intestine.

Animals↗
PubMed1985

Measurement of cell proliferation in microculture using Hoechst 33342 for the rapid semiautomated microfluorimetric determination of chromatin DNA.

We report the development and characterization of a semiautomated method for measurement of cell proliferation in microculture using Hoechst 33342, a non-toxic specific vital stain for DNA. In this assay, fluorescence resulting from interaction of cell chromatin DNA with Hoechst 33342 dye was measured by an instrument that automatically reads the fluorescence of each well of a 96-well microtiter plate within 1 min. Each cell line examined was shown to require different Hoechst 33342 concentrations and time of incubation with the dye to attain optimum fluorescence in the assay. In all cell lines, cell chromatin-enhanced Hoechst 33342 fluorescence was shown to be a linear function of the number of cells or cell nuclei per well when optimum assay conditions were employed. Because of this linear relation, equivalent cell doubling times were calculated from growth curves based on changes in cell counts or changes in Hoechst/DNA fluorescence and the fluorimetric assay was shown to be useful for the direct assay of the influence of growth factors on cell proliferation. The fluorimetric assay also provided a means for normalizing the incorporation of tritiated thymidine ( [3H] TdR) into DNA; normalized values of DPM per fluorescence unit closely paralleled values of percent 3H-labelled nuclei when DNA synthesis was studied as a function of the concentration of rat serum in the medium. In summary, the chromatin-enhanced Hoechst 33342 fluorimetric assay provides a rapid, simple, and reproducible means for estimating cell proliferation by direct measurement of changes in cell fluorescence or by measurement of changes in the normalized incorporation of thymidine into DNA.

Animals↗
PubMed1985

Relationship between zinc and prostaglandin metabolisms in plasma and small intestine of rats.

The effect of zinc nutriture on levels of prostaglandin (PG) E2, F2 alpha and 6-keto-PGF1 alpha in the plasma and small intestine of rats, and that of PGE2 and PGF2 alpha on unidirectional uptake of 65Zn by everted gut sac of rats was determined. When zinc was given intraperitoneally, plasma PGE2 and intestinal PGF2 alpha levels increased, while the intestinal PGE2 and the plasma PGF2 alpha and 6-keto-PGF1 alpha levels decreased in accordance with the amount of zinc given. Oral administration of excess zinc increased intestinal PGE2, PGF2 alpha and 6-keto-PGF1 alpha levels and the plasma 6-keto-PGF1 alpha levels. The intestinal levels of PGE2 increased significantly only in rats on zinc excess diet, and of PGF2 alpha only in rats on a zinc deficient diet. The plasma PGE2 levels in rats on both zinc deficient and zinc excess diets increased but PGF2 alpha levels in zinc deficient rats were greatly reduced compared to controls. Unidirectional zinc uptake by everted gut sac of the rat is also enhanced by PG metabolites. These results are consistent with the view that PGs participate in regulating the zinc transport mechanism in small intestine.

Administration, Oral↗
PubMed1984

Effect of different levels of dietary zinc on longevity of BALB/c mice inoculated with plasmacytoma MOPC 104E.

The effect of different levels of Zn intake on survival was studied in 6 groups of 4-week-old BALB/c mice inoculated with MOPC 104E tumor cells. The first 3 groups received either a Zn-deficient (0.5 microgram Zn/g), a Zn-supplemented (1 mg Zn/g), or a control diet (37.5 micrograms Zn/g) starting 11 days after tumor inoculation (T11). The remaining 3 groups received the same diets starting the day the tumor was implanted (T0). The mean survival of rats beginning the Zn-deficient diet at T11 was significantly increased compared with that of the control group. However, when the same diet was begun at T0, the mean survival of the Zn-deficient group was significantly reduced; for this group the results probably related to the combined adverse effects from prolonged Zn deficiency and to those effects of the tumor itself. Similarly, excess Zn intake significantly prolonged the mean survival when given at T11. However, excess Zn intake at T0 produced no significant effect on survival, probably because of the elevation of plasma Zn level following oral Zn intake that occurred before the establishment of the tumor or possibly because of the inability of the small intestine to absorb excess Zn at T11 when the tumor was fully developed.

Animals↗
PubMed1983

A new low-molecular-weight calcium-binding ligand in rat small intestine.

Three calcium-binding ligands in the cytosol of rat small intestine have been separated using Sephadex G-75 column chromatography. The estimated molecular weights of these ligands were 85,000, 10,000, and 800, respectively. The two high-molecular-weight ligands were found only in young rats, while the low-molecular-weight calcium-binding ligand was found in all age groups and appeared to be a calcium-bound prostaglandin metabolite. Oral administration of arachidonic acid increased and PGE2 decreased in vivo calcium absorption, while PGF2 administration showed no discernible effect on this parameter. These results suggest that the intestinal calcium transport mechanism may be modulated by prostaglandins and related metabolites.

Aging↗
PubMed1983

ADP-ribosylation of nonhistone proteins during the HeLa cell cycle.

ADP-ribosylation of nonhistone proteins during the HeLa cell cycle was investigated. Proteins were radiolabeled by incubating interphase nuclei and mitotic cells with the specific precursor, [32P]NAD. Autoradiograms of two-dimensional gels of total nuclear nonhistone proteins showed a large number of modified species (more than 140). A complex pattern was also found for interphase chromatin. Nuclear scaffolds showed a simpler pattern of four major groups of modified species, which appeared to be the lamins and poly(ADP-ribose) polymerase. The labeling pattern for nonhistones of metaphase chromosomes was fundamentally different than with interphase nuclei. Autoradiograms were dominated by the incorporation of label into poly(ADP-ribose) polymerase.

Adenosine Diphosphate Ribose↗
PubMed1983

Phosphorylation of nonhistone proteins during the HeLa cell cycle. Relationship to DNA synthesis and mitotic chromosome condensation.

Cell cycle variations in the phosphorylation of chromatin-associated nonhistones were determined. Cells were radiolabeled with [32P]orthophosphate and chromatin was obtained by mild digestion of nuclei with micrococcal nuclease. The experiments were performed in the presence of a substrate inhibitor of alkaline phosphatase, beta-glycerophosphate. The results show that, while similar molecular weight species of phosphorylated nonhistones are associated with interphase chromatin through the HeLa cell cycle, the incorporation (32P cpm/micrograms of protein) profiles of selected major phosphononhistones show substantial changes. The most prominent peaks of specific radioactivity occur in the DNA synthesis phase (S phase). The phosphorylation states of the proteins of isolated metaphase chromosomes were also determined. Nonhistone proteins of isolated metaphase chromosomes are strikingly dephosphorylated, especially in comparison to histone H1. The phosphorylation of the major phosphononhistone of chromatin, which has a molecular weight of 55,000, was further characterized by techniques that included one-dimensional peptide mapping in sodium dodecyl sulfate-polyacrylamide gels and nonequilibrium pH gradient slab gel electrophoresis. Phosphoproteins are also components of the nuclear scaffold, and cell cycle variations in these proteins were investigated. The primary phosphorylated species has a molecular weight of 119,000. As with chromatin-associated nonhistones, this nuclear scaffold protein shows substantial incorporation of 32P in S phase, and a high level of incorporation also occurs close to mitosis.

Cell Cycle↗
PubMed1983

Relationship between the functional status of the reticuloendothelial system and the outcome of experimentally induced pancreatitis in young mice.

Physiologically, the main function of alpha 2-macroglobulin is the binding of active endopeptidases rather than their inhibition. The interaction results in a conformational change in the alpha 2-macroglobulin that leads to its rapid elimination by the reticuloendothelial system. In this way, the reticuloendothelial system may help in the regulation of extracellular proteolytic activity resulting from the release of proteinases from injured pancreatic acinar cells in acute pancreatitis. To evaluate this concept, the effect of feeding a choline-deficient diet supplemented with 0.5% DL-ethionine was determined in 4 and 6-wk-old mice in which the reticuloendothelial system was normal, stimulated, or depressed. Stimulating the reticuloendothelial system in 4-wk-old mice significantly (a) decreased the mortality rate; (b) lessened the drop in the plasma content of both alpha 2-macroglobulin and alpha 1-antitrypsin; and (c) decreased the severity of pancreatitis noted microscopically. In contrast, reticuloendothelial suppression in this group of mice had no demonstrable effect. However, when similar studies were done in 6-wk-old mice, in which this diet induces a milder disease, reticuloendothelial suppression significantly increased the mortality rate as compared with normal mice, whereas reticuloendothelial stimulation significantly decreased it. The possible mechanism for the salutory effect of stimulating the reticuloendothelial system on the outcome of diet-induced pancreatitis in mice is discussed.

Age Factors↗
PubMed1980

Effect of calcium and copper on zinc absorption in the rat.

The effect of cupric and calcium ions on zinc absorption was examined in Sprague-Dawley rats. In in vivo studies test solutions containing 7.5 mM 65ZnCl2 alone or in combination with 500 mM of either CuSO4 or CaCl2 were administered intraduodenally to three groups of rats. 2 h later the animals were sacrificed and their organ 65Zn content was determined. The results of these studies revealed that excess cupric ions had no effect on the 65Zn content of rat internal organs, whereas excess calcium ions decreased organs 65Zn content to 40%. Similar results were obtained in in vitro studies using three sets of rat jejunal sacs each filled with one of the above test solutions and incubated in oxygenated Eagle's medium. To investigate the reason(s) for the observed decreased rate of zinc absorption in the presence of excess luminal calcium, we examined zinc transport in 6 sets of jejunal sacs using six test solutions, each containing 7.5 mM 65ZnCl2 with 0, 12.5, 25, 37.5, 50, or 62.5 mM CaCl2. These experiments showed that 65Zn transport from mucosa to serosa was decreased by 40% in the presence of 25.0 mM CaCl2 but lower calcium concentrations had no effect on zinc transport. Increasing the luminal calcium concentration from 25 to 62.5 mM did not cause a further significant decrease in the rate of zinc transport. These results strongly suggest that zinc absorption in the rat is mediated by a transcellular transport process different from that which mediates copper and calcium absorption. The fact that calcium has been shown to reduce passive cation movements via shunt pathways in the gallbladder mucosa suggests the possibility that calcium in high luminal concentration may depress zinc absorption by reducing the passive component of jejunal zinc absorption.

Animals↗
PubMed1978

Role of prostaglandin E2 in zinc absorption in the rat.

The supernatant of cytoplasmic extract of rat small intestine was mixed with 65Zn and subjected to Sephadex G-75 column chromatography. The activity of 65Zn was detected in four peaks with estimated 800, 10,000, 50,000-75,000 mol wt, and larger than 100,000 daltons. The zinc-binding ligand from the 800 mol wt peak was prostaglandin or prostaglandin-like as indicated by ultra-violet absorption spectrum, by absorption spectrum shift in alcoholic potassium hydroxide, by its effects on pulmonary vascular resistance, and by radioimmunoassay. Addition of prostaglandin E2 or prostaglandin extracted from rat small intestine with ethyl acetate into the lumen of intestinal sacs resulted in a two to threefold increase in the activity of 65Zn in the external medium after 15-20 min incubation. The absorption and tissue distribution of orally administered 65Zn were decreased by 60% in indomethacin-treated rats and increased 70% when ethyl acetate-extracted prostaglandin and radioactive zinc were given simultaneously. These data suggest that prostaglandin not only binds zinc, but also facilitates its transport across the intestinal mucosa.

Animals↗
PubMed1978

Hyper-alpha-2-macroglobulinemia in narcotic addicts.

Significant increases of serum alpha-2-macroglobulin (alpha-2-M) were detected in narcotic addicts presenting at a methadone treatment center. The mean alpha-2-M level was 341 +/- 14 mg/dl compared with 231 +/- 8 mg/dl in normal persons (p less than 0.01). In a comparable group of alcoholics with laboratory evidence of hepatic dysfunction the mean alpha-2-M level was 208 +/- 10 mg/dl. Although the serum immunoglobulin M content was also substantially elevated in the narcotic-addict group, no correlation was obtained between the serum content of this protein and alpha-2-M. Similarly, no correlation between alpha-2-M level and serum zinc content was observed. When the values of the trypsin-binding activity of serum measured in 13 addicts, 15 alcoholics with laboratory evidence of hepatic dysfunction, and 16 normal subjects were plotted against the amount of alpha-2-M measured in the same subjects, a linear correlation was obtained between trypsin-binding activity and alpha-2-M. Thus, the significantly increased serum trypsin-binding activity observed in the addicts is that which might be expected if normal alpha-2-M is being accumulated in large amounts as a result of increased macroglobulin synthesis.

Blood Proteins↗
PubMed1978

Alpha2-macroglobulin deficiency in a patient with Ehlers-Danlos syndrome.

A new genetic defect, alpha2-macroglobulin deficiency, was found in a patient with Ehlers-Danlos syndrome (EDS). Other members of the family of five exhibiting this abnormality were the mother and one sister. All members, including the patient, had normal serum albumin and alpha1-antitrypsin levels. The deficiency, reported here for the first time, appears to be inherited by an autosomal co-dominant mode. Statistical evaluation of the dihybrid crosses for independent assortment between EDS and hypo-alpha2-macroglobulinemia showed a probability of 0.7 to 0.75. However, a possible link between EDS and hypo-alpha2-macroglobulinemia is suggested since the observed ratios of four siblings are exactly as expected, assuming that double gene defects are linked in the mother's genotype.

Adolescent↗
PubMed1977

Binding of zinc to alpha-2-macroglobulin and its role in enzyme binding activity.

Physicochemical studies performed on alpha-2-macroglobulin were correlated with the biological activities of this protein. Equilibrium dialysis of the binding of 65Zn by alpha-2-macroglobulin at pH 7.9 showed heterogeneous binding which could be attributed to two classes of binding sites. The site of greatest affinity for zinc had an apparent stoichiometry (n1 in gatoms/mol of alpha-2-macroglobulin monomer) of 12 and an apparent association constant (K1) of 3.06.10(7). The second binding site had an n2 of 60 and K2 of 1.32.10(5). The trypsin binding activity of alpha-2-macroglobulin did not depend on the presence of zinc in this protein since all but traces of this metal could be removed by EDTA without loss of trypsin binding activity. Saturation of site 1 with zinc did not affect the trypsin binding activity of alpha-2-macroglobulin, but binding of the metal by site 2 progressively decreased the trypsin binding activity by causing an irreversable association of the alpha-2-macroglobulin molecules. Removal of excess zinc from alpha-2-macroglobulin did not restore its trypsin binding activity. Our results also indicate that the high zinc content of alpha-2-macroglobulin (320--770 microgram/g protein) reported in the literature is an artifact and that native alpha-2-macroglobulin contains approximately 150--180 microgram Zn/g protein.

Dialysis↗
PubMed1976

A simple, highly sensitive colorimetric method for the determination of zinc in serum.

A simple, reliable, highly sensitive method for the determination of zinc in biological fluids is described. Interfering trace metals are removed as insoluble iodides or hydroxides prior to complex formation of zinc with dithizone in a Tris-buffered trichloroacetate centrifugate. Absorbance of the chelate is read at 555 nm. The sensitivity of the new method is comparable to that of atomic absorption spectrophotometry, and the results of zinc determinations of 23 sera by the two procedures agree to within acceptable limits of experimental error.

Absorption↗