Biomedical subjects

S Kreczko

Publications and source records attributed to S Kreczko.

At least 19 recordsLinked to original sources

PubMed2000

[Alpha-fetoprotein: diagnostic value in hepatic disorders].

The serum AFP concentration in man falls rapidly after birth and its synthesis in adult life is normally repressed. However, AFP is synthesized in large amounts by human hepatocellular carcinoma in greater than 70% of patients. Elevation of serum AFP in benign hepatic diseases such as acute and chronic viral hepatitis as well as toxic liver injury is associated with small transient increases in serum AFP. Therefore, quantification of serum alpha-fetoprotein (AFP) has been widely used as a diagnostic marker for hepatocellular carcinoma. Measurement of serum AFP levels have also been used in screening populations at high risk of human hepatocellular carcinoma such as those with cirrhosis or carriers of hepatitis B virus. However the specificity of the screening test in patients with only modestly raised AFP (below 400 ng/ml) is low, and false-positive results are frequent. A wide range of overlap in the distribution of serum AFP levels between hepatocellular carcinoma and chronic liver disease patients were observed mainly among HBsAg (+) patients. Therefore the specificity and predictive value of AFP are lower in HBsAg(+) than in HBsAg(-) patients, especially when AFP is between 25 and 200 ng/ml. In patients with chronic hepatitis B, the analysis of lectin reactivity of AFP has the advantages over quantification of serum AFP to detect HCC-specific variants in serum samples with only moderate raised AFP levels. Measurement of AFP serves as an important tool in the care and management of patients with benign and malignant hepatic disorders.

Adult↗

PubMed1999

Influence of secretin and caerulein on acid phosphatase activity in human saliva.

Experimental studies have demonstrated a structural and functional correlation between the pancreas and salivary glands. Therefore, one may suppose that caerulein plus secretin, used in functional exploration of the exocrine pancreas, could exert an influence on acid phosphatase activity (AcP) and its isoenzymes (tartrate sensitive-TsAcP, tartrate resistant-TRAP acid phosphatases) in whole saliva in humans. The current study was conducted in 14 asymptomatic volunteers (six woman and eight men, mean age 34, range 27-45). Salivary secretions were collected under basal conditions (intravenous infusion of 0.15 mol l-1 NaCl) and during intravenous infusion of secretin plus caerulein at different doses. Stimulation with secretin (50 mKE kg-1 min-1) and caerulein (2.5 ng kg-1 min-1) resulted in a marked and rapid decrease of salivary flow rate. TRAP activity decreased during the first 20 min of hormonal infusion (1.09 +/- 0.19 mU ml-1 vs. 1.93 +/- 0.18 mU ml-1, 1.16 +/- 0.12 mU ml-1 vs. 1.86 +/- 0.17 mU ml-1, p < 0.05). AcP and TsAcP activity during intravenous infusion of secretin plus caerulein remained unchanged. These results point to a wider than expected participation of the digestive system in hormonal control of biochemical processes taking place inside the oral cavity.

Acid Phosphatase↗

PubMed1999

[Serum levels of interleukin 6 (IL-6) and soluble IL-6 receptor (sIL-6R) in children and adolescents with Graves-Basedow disease].

The concentration of interleukin 6 (IL-6), soluble IL-6 receptor (sIL-6R) and intercellular adhesion molecule-1 (sICAM-1) was assayed in 24 children with Graves' disease, aged 6.5-17 years, before treatment with methimazole, during clinical and biochemical remission (8 weeks), and following the eighteen-month therapy with the thyrostatic. ELISA method was used to determine the concentration of interleukin 6, sIL-6R and sICAM-1. An increase was observed in serum concentration of IL-6 and its receptor sIL-6R and soluble intercellular adhesion molecule-1 in the course of Graves' disease. A significant reduction in sIL-6R (8 weeks) and IL-6 (18 months) was noted after therapy with methimazole. A positive correlation was found between microsomal antibodies and the concentration of sICAM-1 and sIL-6R, and between antithyroglobulin antibodies and concentration of sIL-6R in children with fresh hyperthyroidism. No correlation was revealed between the level of thyroid hormones and the concentration of cytokines and adhesion molecules.

English Abstract↗

PubMed1998

[The role of selected serologic markers in the diagnosis of autoimmune hepatitis].

Autoimmune hepatitis (AIH) is a progressive inflammatory liver disease characterized by specific duration of symptoms (above 6 months), 3- to 10-fold elevation in serum aminotransferase activities, 2-fold elevation in gamma-globulin, high titers (above 1:40) of circulating autoantibodies. Antinuclear antibodies (ANA), smooth muscle antibodies (SMA), and antibodies to liver/kidney microsome type 1 (anti-LKM1) are the commonly available markers of AIH. SMA and ANA lack disease specificity and they are present commonly in different liver diseases. Anti-LKM1 usually connote a type 2 form of AIH which involves children and responds to corticosteroid therapy. Other autoantibodies, such as those against actin (SMA-AA), the liver-cytosolic antigen (anti-LC1), the liver-specific membrane lipoprotein (anti-LPS), asialoglycoprotein receptor (anti-ASGPR), have greater disease specificity but less availability.

Adult↗

PubMed1996

[Detection of the parasite Giardia intestinalis during feces examination with immunoenzymatic and microscopic methods].

Detection rate of G. intestionalis in feces with direct microscopy has been compared with the immuno-enzymatic technique detecting protein GSA 65 with Alexon Inc., ProSpec T/Giardia reagents kit. The results obtained with both methods have further been compared with those obtained by microscopic examination of the duodenal content. Detectability of Giardia intestinalis with EIA technique with the use of ready-made kit has been assessed. Feces have been collected from 371 patients. Protein GSA 65 has been present in 170 samples, 45.8%, examined with the use of ProSpec-T/Giardia kit. Giardia intestinalis cysts have been detected microscopically in the feces of 37 patients, i.e., in 22.3%. Microscopic examinations carried out by three independent examinators have shown marked diversity in the rate of positive results, being 0.1% (examinator A), 28.6% (B), and 45.2% (C). Comparison of G. intestinale detectability of all 3 techniques used have shown absence of protein GSA 65 in 2 out of 9 examined patients. However, trophozoites have been present in the duodenal content. Test performed with kits made by Alexon Inc. and DIALAB have given 45.8% and 60.7% of the positive results, respectively.

Adolescent↗

PubMed1990

Characterization of biologically active, platelet-derived growth factor-like molecules produced by murine erythroid cells in vitro and in vivo.

Platelet-derived growth factor (PDGF) is an important serum regulator of erythropoiesis in vitro. We have now obtained evidence suggesting that PDGF-like molecules may also modulate erythropoiesis in vivo. Western blot analysis of cytoplasmic extracts from Rauscher murine erythroleukemia cells and phenylhydrazine-treated mouse splenic erythroid cells revealed the presence of several PDGF-like proteins. The presence of PDGF-like proteins in the cytoplasm of these two erythroid cell types was confirmed by immunohistochemical staining. Using a serum-free biologic assay, PDGF-like biological activity was found in cell lysates and conditioned medium of both Rauscher cells and phenylhydrazine-treated mouse erythroid cells. Subcellular localization experiments revealed the biological activity to be concentrated in the cytosolic fraction. Using a series of antibodies to hematopoietic growth factors we demonstrated that PDGF-like biological activity was specifically immunoprecipitated by both monoclonal and polyclonal anti-human PDGF antibodies but not by antibodies to burst-promoting activity, granulocyte-macrophage colony-stimulating factor, IL-3, or erythropoietin. Taken together, the data are consistent with the hypothesis that PDGF-like molecules play a role in the regulation of mammalian erythropoiesis in vivo.

Animals↗

PubMed1989

DNA topoisomerase inhibitors block erythropoiesis and delay hemoglobinization in vitro.

To examine the importance of topological constraints on DNA during erythroid development, we measured the effects of camptothecin and teniposide, two tumoricidal agents which are also specific inhibitors of type I and type II topoisomerases respectively, on the formation of hematopoietic colonies by cultured human bone marrow cells. When added to bone marrow culture, each inhibitor alone impairs the formation of early BFU-E-derived colonies, late CFU-E-derived colonies and mixed hematopoietic (CFU-GEMM-derived) colonies by up to 100%. Inhibition of colony formation is directly related to the time of inhibitor addition and the inhibitor concentration tested. Although either inhibitor alone reduces colony formation by 90%, when added together at a submaximal concentration, camptothecin and teniposide exert a synergistic suppressive effect. Furthermore, addition of topoisomerase inhibitors to culture impairs hemoglobinization of colony erythroblasts in a time-dependent fashion. In contrast to the effects of topoisomerase inhibitors, the antiproliferative agent aphidicolin reduces erythroid colony number and size without altering hemoglobinization of colony erythroblasts. Since neither topoisomerase inhibitor alters the morphology of cultured cells, the capacity of cells to exclude trypan blue or the potential to form erythroid colonies through the interval required for the first progenitor cell division, it is unlikely that camptothecin or teniposide are cytotoxic to hematopoietic cells. Human mononuclear cells enriched in bone marrow lymphocytes and nucleated erythroblasts from both human and mouse sources release DNA into the detergent soluble fraction. Release requires functional topoisomerases and is altered by acute exposure to topoisomerase inhibitors. Our results suggest that topoisomerases are critical not only to proliferation but also to differentiation of human marrow erythroid progenitor cells and stem cells in culture.

Aphidicolin↗

PubMed1989

Dual role of fibronectin in hematopoietic differentiation.

The adhesive glycoprotein fibronectin provides anchorage for fibroblasts and hematopoietic progenitor cells in vitro. Fibronectin also demonstrates growth factor activity for fibroblasts; however, there is no available information regarding its role as a hematopoietic growth factor. To distinguish growth factor activity of fibronectin from its anchorage activity for hematopoietic progenitors, we assessed the ability of purified human plasma fibronectin to promote human bone marrow erythroid, granulocyte-macrophage (GM) and mixed granulocyte-erythroid-macrophage-megakaryocyte (GEMM) colony formation in liquid suspension, methylcellulose, and fibrin clots under serum-free conditions. Addition of fibronectin to methylcellulose cultures, or to cultures formed in fibrin clots, using fibrinogen depleted of fibronectin by preadsorption over gelatin-Sepharose and clotted with thrombin, resulted in up to a twofold enhancement of proliferation of erythroid burst-forming units (BFU-E), erythroid colony-forming units (CFU-E), and CFU-GEMM. This effect was concentration-dependent up to a fibronectin supplement of 100 micrograms/mL. By contrast, CFU-GM proliferation was not affected by the addition of fibronectin to the cultures. Fibronectin-adherent marrow cells overlaid with liquid medium formed both early and late-appearing erythroid colonies, whereas similarly cultured plastic-adherent marrow cells did not. Erythroid colony formation was observed in cultures of fibronectin-adherent marrow cells overlaid with methylcellulose but not in cultures of plastic-adherent marrow cells under the same conditions. Finally, the erythroid growth-promoting activity of fibronectin was inhibited by arginyl-glycyl-aspartyl-serine (RGDS), a tetrapeptide that competitively blocks the interaction of fibronectin with its receptor. We conclude that fibronectin plays a dual role in hematopoiesis: providing (a) anchorage for erythroid and primitive progenitors, and (b) as a proliferative stimulus for these hematopoietic cells. Both activities may be mediated by the cell adhesion domain of the molecule.

Adult↗

PubMed1988

3'-Azido-3'-deoxythymidine (AZT) inhibits proliferation in vitro of human haematopoietic progenitor cells.

Peripheral blood cytopenias are a serious, dose-limiting toxicity of AZT therapy in patients infected by HIV. To evaluate the mechanism by which cytopenias develop, AZT effects of haematopoietic differentiation and growth were measured in serum-free, nucleoside-depleted cultures of normal human bone marrow. In contrast to native thymidine, AZT suppressed the proliferation of erythroid, granulocyte/macrophage and primitive haematopoietic stem cells in a dose-related and time-dependent fashion. Relative progenitor sensitivity varied, with half-maximal concentrations of 1-5 microM and 20-40 microM AZT for inhibition of erythroid and nonerythroid progenitor cell growth, respectively. Inhibition was observed over full ranges of concentrations of haematopoietic tissue-specific regulators (human erythropoietin, colony-stimulating activity, interleukin-3 and lymphocyte conditioned medium) and of platelet-derived growth factor (PDGF), an agent that enhances erythropoiesis in vitro via accessory marrow stromal elements. Furthermore, suppression was similar in cultures of marrow cells that were depleted of accessory populations, suggesting that its action is directed at progenitors. Finally, when deoxythymidine was added in increasing amounts to cultures with a half-maximal concentration of AZT, inhibition was abrogated. We conclude that AZT is a potent inhibitor of haematopoiesis in vitro, and that erythroid progenitors are particularly sensitive to its action. These results may explain the marrow hypoplasia that occurs during AZT administration in vivo.

Antiviral Agents↗

PubMed1988

Acetylated lipoproteins impair erythroid growth factor release from endothelial cells.

Endothelial cells are a known source of hematopoietic growth-enhancing factors, including platelet-derived growth factor (PDGF). In addition, endothelium interacts directly with plasma lipoproteins which have been shown to modulate hematopoiesis. To determine the relationship of these properties, we measured the release of an erythroid growth-enhancing factor from bovine endothelial cells under lipid-loaded and control conditions. Human bone marrow cells cultured under serum-free conditions form more erythroid, granulocyte/macrophage, and mixed hematopoietic colonies when supplemented with endothelial cell-conditioned medium (ECCM) than do controls (P less than 0.05). The activity is expressed over a wide range of erythropoietin, lymphocyte-conditioned medium (LCM), recombinant human interleukin-3, and colony-stimulating factor (CSF) concentrations, and is related to ECCM dose. In contrast, enhancing activity in ECCM prepared with 0-400 micrograms/ml acetylated low density lipoproteins (AcLDL) or native LDL is diminished to 0% in a dose-dependent fashion (relative to ECCM from unexposed cells or from cells incubated with very low density lipoproteins, P less than 0.05). Upon dilution, medium prepared from cells incubated with LDL shows a rightward shift in the dose-response curve for erythroid colony formation, while that prepared from AcLDL loaded cells demonstrates a downward shift, indicating that the inhibitory activities are kinetically distinct. Delipidation of ECCM prior to addition to marrow culture removes the inhibitory action of native LDL (P less than 0.05) but not that of AcLDL (P greater than 0.10). Immunochemical analysis suggests that the erythropoietic activity in ECCM is unrelated to that of PDGF, recombinant human CSF, and erythroid burst-promoting activity (BPA) present in LCM. This conclusion is supported by Northern blot analysis of endothelial cells using a cDNA probe for the v-sis homologue of the PDGF beta chain and by immunoprecipitation of metabolically labeled PDGF. The relative amounts of c-sis transcripts and of secreted PDGF were similar in endothelial cells incubated with or without AcLDL. We conclude that AcLDL impair the synthesis or release of an erythropoietic growth-enhancing factor(s) which is biologically distinct from PDGF and BPA present in LCM.

Acetylation↗

PubMed1988

Contractile proteins participate in release of erythroid growth regulators from mononuclear cells.

We have investigated the role of contractile proteins of circulating mononuclear cells in generation of membrane-associated, erythroid growth regulatory molecules. Lymphocytes and monocytes were incubated under serum-free conditions without and with cytochalasin B, cytochalasin D, or colchicine, and effects on positive and negative erythropoietic activities were determined in cell membranes and in surface membrane vesicle-rich pellets and supernatants of dialyzed medium conditioned by the cells. In serum-free cultures of human bone marrow, plasma membranes and exfoliated membrane-derived vesicles from cytochalasin-treated lymphocytes lost their capacity to support the formation of erythroid bursts, while monocyte membrane-associated inhibitory activity was abolished by preincubation with cytochalasin. In contrast, membrane-associated activities of colchicine-treated cells were unaffected. Cytochalasin-induced alterations of membrane regulatory molecules were observed in a dose-dependent fashion over a wide range of concentrations (1 to 100 micrograms/mL) tested. However, the capacity of membrane vesicle-free supernatants of medium conditioned by lymphocytes or monocytes was unaffected by cytochalasins, regardless of drug concentration used. Lysates of cytochalasin B-treated cells inhibited the activity of deoxyribonuclease I to a greater degree than did lysates of untreated cells, suggesting that the relative amount of monomeric actin is increased in the cytoplasm of treated cells. Furthermore, results of experiments with D-glucose and with cytochalasin D suggest that cytochalasin effects are independent of alterations in glucose metabolism. The data indicate that expression of plasma membrane-associated regulators is sensitive to agents that block polymerization of actin. They raise the possibility that changes in distribution of actin between unpolymerized and filamentous pools may influence the organization and/or function of mononuclear cell surface-associated erythroid regulatory molecules.

Actin Cytoskeleton↗

PubMed1988

A monoclonal antibody to exfoliated surface vesicles that recognizes a membrane-associated erythroid burst-promoting activity.

A monoclonal antibody (MoAb) recognizing a membrane-associated erythroid burst-promoting factor was prepared by immunizing BALB/c mice with plasma membrane-derived vesicles exfoliated from lymphocytes under serum-free conditions. Hybrids secreting antibody reactive with lymphocyte plasma membranes were formally cloned and IgG was purified from monoclonal supernatants or from BALB/c mouse ascites fluid. Two clones (D3-E4 and D3-G9) were found to suppress burst forming unit-erythroid (BFU-E) proliferation when added directly to serum-free human marrow culture. Inhibition to a level of 100% was observed in a dose-dependent fashion over a wide range of antibody concentrations (0-200 micrograms/mL). Neither antibody altered the proliferation of colony forming unit-granulocyte macrophage (CFU-GM) or colony forming unit-granulocyte-erythroid-monocyte-megakaryocyte (CFU-GEMM) progenitor cells in human bone marrow culture. The D3-E4 clone was found to produce an IgG1 antibody which adsorbs an erythroid burst-promoting activity (BPA) from supernatants of, and octylglucoside extracts of shed vesicles present in, serum-free, lymphocyte conditioned medium (LCM), and which recognizes a vesicular protein of Mr approximate 30,000 on immunoblots of membrane proteins electrophoresed on sodium dodecyl sulfate (SDS)/polyacrylamide and transferred to nitrocellulose. In contrast, the D3-G9 clone was found to produce an IgG1 cytotoxic antibody. These antibodies will be important to the study of cell-cell and growth factor-cell interactions in vitro.

Animals↗

PubMed1987

B-lymphocytes as a source of cell surface growth-promoting factors for hematopoietic progenitors.

Although B cells reside in the bone marrow, little is known concerning their functional role in hematopoiesis. We have measured the effects of surface membrane factors released from unstimulated, circulating B cells of normal donors and patients with chronic lymphocytic leukemia on human hematopoiesis in vitro. Leukemic cells augment erythroid burst formation by allogeneic blood cells (p less than 0.05). The stimulatory effect is increased in cultures containing a high B-cell seeding density, and is decreased in those with a high peripheral blood mononuclear cell seeding density. Medium conditioned by B cells (CM) from the circulation or bone marrow stimulates the formation of erythroid bursts, granulocyte-macrophage colonies, and mixed colonies containing granulocytes, erythroblasts, monocytes, and megakaryocytes (GEMM) in serum-free cultures of allogeneic and autologous marrow (p less than 0.05). This effect is localized primarily to surface membrane vesicle-rich pellets of CM. Screening of several hematopoietic and nonhematopoietic cell types reveals that membrane vesicle-associated activity is released from B cells and mitogen-stimulated, circulating T cells. In contrast, vesicles shed from freshly isolated, resting T cells, continuous T-cell leukemia cell lines, erythrocytes, and endothelial cells do not express the activity (p greater than 0.10). The stimulatory activity is augmented in cultures of marrow cells that are depleted of B4 antigen-positive lymphocytes but not of T-lymphocytes, suggesting that endogenous release of the factor(s) occurs during incubation. Furthermore, membranes partially purified from leukemic B cells also express the activity. Together with our findings that (1) the growth enhancing factor(s) is solubilized by octylglucoside, and that (2) the factor can be immunoprecipitated with BPA-neutralizing, antimembrane IgG, our results suggest that the erythropoietic activity is an integral membrane protein that may be immunologically related to BPA. The relationship of the erythroid burst stimulatory factor to other hematopoietic activities found in CM pellets is unknown.

B-Lymphocytes↗

PubMed1987

Stimulatory effects of plasma from patients with acute nonlymphoblastic leukemia on early erythroid progenitors and pluripotent stem cells.

To examine mechanisms of cytopenia in acute nonlymphoblastic leukemia (ANLL), we determined whether leukemic plasma (LP) contains growth-promoting factors that support mammalian erythroid progenitor and pluripotential stem cell proliferation in vitro. When added to serum-free cultures of human bone marrow and peripheral blood cells, LP from anemic patients with ANLL stimulated erythroid burst formation to greater levels than did normal human plasma (p less than 0.05 for each). While LP also enhanced erythroid burst development in murine bone marrow cells, preincubation of marrow cells with LP did not alter the formation of splenic colonies (CFU-S-derived colonies) in irradiated mice (p greater than 0.10). To determine whether erythropoietin or other growth factors (functionally similar to burst-promoting activity, BPA) are important in mediating the erythropoietic effects observed in vitro, LP was preabsorbed with monospecific IgG raised against human erythropoietin or human BPA. Although elevated erythropoietin levels were found in each LP, preabsorption with antierythropoietin IgG did not alter its capacity to enhance human burst formation. In contrast, preabsorption with antimembrane IgG capable of recognizing human BPA abrogated the stimulatory effects of LP (p less than 0.05). In addition, LP was found to increase the percentage of murine CFU-S that are synthesizing DNA by the (3H) Tdr suicide technique, an effect which was not abrogated by preabsorption of LP with monospecific IgG raised against human BPA. We conclude that both erythropoietin and BPA are appropriately increased in ANLL. In addition, a factor is present in LP which induces DNA replication in murine pluripotential stem cells.

Absorption↗

PubMed1986

L-triiodothyronine augments erythropoietic growth factor release from peripheral blood and bone marrow leukocytes.

To investigate cellular mechanisms involved in thyroid hormone stimulation of erythropoiesis, we studied the response of erythroid burst-forming unit (BFU-E) proliferation to L-triiodothyronine (L-T3) in a serum-free culture system. When added directly to culture, L-T3 stimulates erythroid burst formation by normal human bone marrow cells. In contrast, granulocyte-macrophage colony formation is unaffected. Enhancement of erythroid burst formation by L-T3 required the presence of nylon wool adherent and/or B-4 antigen-positive light-density marrow populations. Addition of other erythropoietic factors including platelet-derived growth factor and insulinlike growth factor II did not abrogate this apparent cellular requirement. Pulse exposure of marrow and peripheral blood mononuclear cells (greater than 95% lymphocytes) to L-T3 accelerates the release of a soluble factor that augments BFU-E proliferation into serum-free liquid culture medium. Time-course studies show that this factor appears in conditioned medium (CM) coincidentally with erythroid burst-promoting activity (BPA). Furthermore, incubation of CM with an antibody known to react with and adsorb BPA from solution removes the inducible mitogen. Biochemical analysis of CM prepared from unexposed and L-T3 pulse-exposed cells indicates that the rate of protein appearance is accelerated by L-T3 in a fashion that immediately precedes growth factor release and that several polypeptides are quantitatively increased. We conclude that unlike erythropoietin, which is mitogenic for progenitor cells directly, L-T3 enhances BFU-E proliferation indirectly by augmenting the release of soluble BPA-like molecules from accessory cells in culture.

Bone Marrow↗

PubMed1985

Interactions of insulin, insulinlike growth factor II, and platelet-derived growth factor in erythropoietic culture.

To examine the influence of insulin and insulinlike growth factor (IGF) on erythropoiesis, we tested their effects in human bone marrow cultures prepared with biochemically defined medium or a platelet-poor plasma-derived serum (PDS) that was depleted of hormones by adsorption to activated charcoal. Erythroid colony formation was enhanced two- to threefold by 10 ng/ml of electrophoretically pure IGF-II and 100 ng/ml of highly purified insulin (P less than 0.05). Dose-response curves for IGF-II were parallel to and shifted by one to two orders of magnitude to the left relative to those for insulin. When added together to culture, IGF-II and insulin expressed additive activities. In contrast, their activities were synergistic with those of erythropoietin and burst-promoting activity. The erythropoietic actions of IGF-II and insulin were similar in PDS and whole blood serum (WBS) containing cultures. Furthermore, when added to cultures with electrophoretically pure platelet-derived growth factor, their respective activities were synergistic. We conclude that insulin and IGF-II potentiate human marrow erythropoiesis in vitro. Their activities appear to be mediated by a similar receptor or postreceptor system.

Cells, Cultured↗

PubMed1985

Primary human marrow cultures for erythroid bursts in a serum-substituted system.

To determine environmental requirements for erythroid burst formation in primary culture, we added human bone marrow cells to serum-depleted methylcellulose, agar, or fibrin clot cultures. Optimal BFU-E proliferation was present in cultures prepared with Iscove's modified Dulbecco medium, 248 micrograms/ml transferrin, 1.63 micrograms/ml ferric chloride, 117 micrograms/ml bovine serum albumin, and each of seven preparations of erythropoietin. Burst number was comparable to that in serum containing culture. Reducing sodium dodecyl sulfate electrophoresis of commercial albumin preparations showed them to contain abundant lipoproteins. Results of experiments with human plasma albumin found to be greater than 98% pure by one- and two-dimensional gel electrophoresis and delipidated albumin indicate that an albumin source is needed for burst formation to occur. Together with albumin, exogenous phosphatidylcholine but not phosphatidylserine augmented burst number. Bursts routinely appeared in serum-depleted culture without added burst-promoting activity (BPA). However, leukocyte-conditioned medium (LCM) and its high-speed supernatant and pellet fractions enhanced burst formation. Antimembrane IgG capable of neutralizing BPA reduced burst number to a level below that achieved in LCM-depleted culture, suggesting that endogenous BPA was inactivated. We conclude that human marrow BFU-E proliferation requires iron-saturated transferrin, albumin, and erythropoietin. Exogenous BPA and phospholipids enhance but are not essential for burst formation to proceed in primary culture.

Blood↗

PubMed1981

Glycoprotein metabolism in the guinea-pig gastric mucosa in chronic metribuzin poisoning.

Forty male guinea pigs weighting 400--600 g, 8 months old, were given metribuzin directly into the gastric lumen over a period of 30 days (20 animals) or 90 days (20 animals), 6 times a week. The intoxicated animals showed in the gastric mucosa a significant decrease in glucosamine isomerase activity and a significant increased in beta-glucosidase and beta-galactosidase activity. The results suggest that the biosynthesis of the sugar moiety of glycoproteins is depressed, the degradation of glycoproteins is stimulated by metribuzin.

Animals↗