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Biomedical subjects

V Stolc

Publications and source records attributed to V Stolc.

At least 55 records · Page 3Linked to original sources
PubMed1979

Inhibition of 14C-labeled amino acid incorporation into protein by particles and surface-active agents in human granulocytes.

Contact of human polymorphonuclear leukocytes with latex or zymosan particles resulted in inhibition of incorporation of 14C-labeled amino acids into protein in the phagocytosing cells. The surface-active agents, concanavalin A and digitonin, exerted the same inhibitory activity on 14C-labeled amino acid incorporation into protein in human granulocytes. The inhibition of 14C label incorporation was dose dependent and the half-maximal effect per 10(7) cells was found at 0.8 mg of latex (0.79 micrometer in diameter), 0.25 mg of serum-coated zymosan and 35 microgram of digitonin/ml of the incubation medium. Amino acid transport (14C-labeled amino acids or amino[14C]isobutyrate) was the same in the resting and phagocytosing granulocytes. These results suggest that the incorporation of 14C-labeled amino acids into protein in human granulocytes is in some way connected to alteration in the cell plasma membrane.

Amino Acids↗
PubMed1979

Characterization of iodoproteins secreted by phagocytosing human polymorphonuclear leukocytes.

Several proteins, glycoproteins, and iodoproteins are secreted from human polymorphonuclear leukocytes during phagocytosis of inert latex particles. The amount of 125I-labeled proteins increases during 10 to 60 min of incubation. The 125I-iodoproteins secreted into the incubation medium during the phagocytosis were first separated on Sephadex G-150 column and then characterized by column chromatography on Sepharose 4B, Sephadex G-200, and G-100. Three 125I-iodoproteins were found with the molecular weights of 580,000, 100,000, and 22,000. The molecular mass of 15 protein subunits calculated after sodium dodecyl sulfate-polyacrylamide gel electrophoresis ranged from 11,000 to 86,000 daltons. Four of the protein subunits were labeled with 125I. Their molecular weights were 63,000 to 69,000, 44,000 to 49,000, 22,000, and 11,000. In addition to iodoproteins, several 125I-labeled peptides and compounds were found by column chromatography on Bio-Gel P-2 and P-10. The 125I-iodoproteins are not secreted from resting or boiled granulocytes, and their production is 92 to 98% inhibited by 1 mM KCN or 1 mM sodium azide. The double-labeling technique with [125I]- and [131I]-iodine suggests that the iodoproteins formed in the phagocytosing granulocytes or secreted into the incubation medium are not identical.

Granulocytes↗
PubMed1979

Serum ferritin and bone marrow iron stores. I. Correlation with absence of iron in biopsy specimens.

Serum iron, total iron-binding capacity, and percentage saturation of transferrin have classically been used to demonstrate a hypoferremic state; however, these tests may not discriminate between depleted iron stores and conditions associated with defective reticuloendothelial release of iron. Estimation of stainable iron in the bone marrow biopsy specimen is then the most practical way to assess body iron stores. With the availability of a radioimmunoassay procedure for serum ferritin, we undertook a prospective study to determine whether serum ferritin concentrations might replace assessment of the marrow biopsy iron stores as an indicator of hypoferremia. Iron stores were absent from bone marrow biopsy specimens from 104 patients. A good correlation between low serum ferritin levels and absence of iron stores in biopsy specimens was found for 91 patients (87.5%). Thirteen (12.5%) had normal serum ferritin concentrations with absence of biopsy iron. These individuals had hematopoietic malignancies or active hepatic disease, or were receiving iron therapy. In this group, a bone marrow biopsy would still be necessary for evaluation of a hypoferremic state, even though the serum ferritin concentration might be normal.

Adult↗
PubMed1979

Effect of colchicine on PGE1 stimulation of cAMP1 formation in human lymphoblastoid and normal lymphocytes.

PGE1 increased cAMP level in human lymphoblastoid cells (RPMI 1788) after 5-60 min of incubation at 37 degrees C. A gradual decrease of cAMP concentration was found at the later time intervals. Colchicine significantly potentiated the stimulatory effect of PGE1, although it did not have any effect on cAMP level in control lymphoblastoid cells. The maximal effect of colchicine on PGE1 stimulation of cAMP formation was at the 0.1-1.0 microM level. Human lymphocytes also responded with increased cAMP formation to colchicine addition. In contrast, no stimulatory effect of colchicine was found in human granulocytes.

Cell Line↗
PubMed1977

Mechanism of regulation of adenylate cyclase activity in human polymorphonuclear leukocytes by calcium, guanosyl nucleotides, and positive effectors.

This study presents the results of a kinetic investigation of adenylate cyclase in human polymorphonuclear leukocytes. In the presence of a saturating concentration of substrate (1 mM), the basal activity was increased severalfold by increasing Mg2+ from 1 to 25 mM. A Hill coefficient of 1.9 was obtained for Mg2+ or ATP. The data suggest cooperative interactions between the substrate binding sites in the neutrophil adenylate cyclase complex. It has been observed that guanyl-5'-yl imidodiphosphate (Gpp(NH)p) (S0.5 = 10 MUM) significantly increased and Ca2+ (S0.5 = 0.5 MM) significantly decreased only the Vmax without affecting the Hill coefficient or S0.5 for ATP. The Hill coefficients for Ca2+ or Gpp(NH)p were 0.9 and 0.8, respectively. The Hill coefficient for Ca2+ was not changed by the increased Gpp(NH)p concentrations. It appears that neutrophil adenylate cyclase has distinct binding sites for Gpp(NH)p and Ca2+, one for each compond. The binding of ligands is not changed by the other effectors and the action is directed only toward the Vmax of the enzyme. The stimulatory action of positive effectors (prostaglandin E1, isoproterenol, histamine) was enhanced by Gpp(NH)p and depressed by Ca2+. No preferential stimulation by Gpp(NH)p nor inhibition by Ca2+ of the action of the positive effectors has been found. The data suggests that only one type of catalytic subunit responds to the action of several positive effectors. Extracellular Gpp(NH)p or Ca2+ do not affect the cyclic adenosine 3':5'-monophosphate (cAMP) level in whole neutrophils and the effect of positive effectors on cAMP production is also not significantly changed by 5 mM Ca2+ or 0.1 mM Gpp(NH)p. Ionophore A23187 in the presence of 5 mM Ca2+ enhances Ca2+ entry into cells and decreases the basal cAMP formation. It appears that Gpp(NH)p or Ca2+ act only at the intracellular site of the adenylate cyclase complex.

Adenosine Triphosphate↗