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Biomedical subjects

E Puszkin

Publications and source records attributed to E Puszkin.

At least 19 recordsLinked to original sources
PubMed1996

Alterations in platelet function in patients receiving interleukin-6 as cytokine therapy.

Platelet function in 12 cancer patients was studied sequentially over 97 hr of interleukin-6 (IL-6) daily bolus or continuous infusion (C.I.) therapy. During this period, enhanced ex vivo agonist-induced platelet maximum aggregation (MA) was paralleled by an increase in plasma levels of TXB2 and PF4 as measured by RIA and ELISA, respectively. Platelet-rich plasma (PRP) specimens from bolus IL-6-treated patients demonstrated an increased incorporation of actin-binding protein and myosin in the cytoskeletal core (triton insoluble residue) as shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in comparison to control specimens. Similarly, the integrin glycoprotein IIIa (GPIIIa) was also observed to be retained into the cytoskeleton by immunoblot. A significant decrease in hypotonic shock response (HSR) was observed over 87 hr of treatment in IL-6 C.I. patients, whereas in IL-6 bolus patients, a significant increase in HSR occurred immediately after the bolus, which was followed by a significant decrease in HSR after 23 hr. These results suggest that IL-6 alters platelet function in vivo.

Adenosine Diphosphate↗
PubMed1995

Characterization of tumor-induced platelet aggregation: the role of immunorelated GPIb and GPIIb/IIIa expression by MCF-7 breast cancer cells.

Tumor cell induced platelet aggregation is thought to be an early step in the metastatic process. Here we show that platelet aggregation induced by MCF-7 cells is mediated, in part, through an ADP-dependent mechanism based on inhibition of aggregation by pretreatment of the tumor cells with apyrase and the identification of ADP in tumor cell-free supernatants by HPLC. By applying immunocytochemical and flow cytometric techniques, we demonstrate that platelet immunorelated glycoproteins, GPIb, GPIIb/IIIa, GPIb/IX, and the integrin alpha v subunit are expressed on the surface of MCF-7 cells. The expression of an immunorelated GPIb was further confirmed by immunoblot and autoradiography of 125I-labelled MCF-7 cells. MCF-7 cell immunoblot preparations demonstrated one major protein reactive to an anti-GPIb alpha MoAb under nonreduced conditions with a molecular weight of 200 kD and two major proteins reactive with the anti-GPIb alpha MoAb under reduced conditions with molecular weights of 92 kD and 38 kD. Platelet aggregation is inhibited by preincubating the MCF-7 cells with antibodies to GPIb and GPIIb/IIIa. These findings document expression of adhesive glycoproteins by MCF-7 cancer cells and suggest that these receptors, together with ADP, play a role in tumor induced platelet aggregation.

Breast Neoplasms↗
PubMed1995

Morphologic and ultrastructural evidence of interleukin-6 induced platelet activation.

The in vitro effect of IL-6 on platelet activation was investigated. When human platelets were incubated with high (1,000 ng/ml) or low (1 ng/ml) dose IL-6, expression of GMP-140 was enhanced by 42% (N = 6; P < 0.009) and 46% (N = 6; P < 0.061) in 1 hr low and high dose IL-6-platelet incubations, respectively, as assessed by flow cytometry. In platelet specimens incubated with high dose IL-6 for 3 hr, a 70% (N = 6; P < 0.009) increase in GMP-140 expression over control was observed. Parallel high dose IL-6 incubations subjected to scanning electron microscopic studies revealed a 3.4-fold increase (N = 6; P < 0.001) in spheroid morphologic platelet forms in 1 hr incubations in comparison to control platelet preparations, whereas in 3 hr IL-6-platelet incubations, a 96% increase in dendritic platelet forms was observed (N = 6; P < 0.001). Significant increases in platelet ATP levels were observed in both 1 min and 1 hr high dose and low dose IL-6 platelet incubations. In 3 hr high dose-IL-6 platelet incubations, a significant 18% (N = 8; P < 0.001) decrease in platelet ATP was parallelled by a significant 40% increase (N = 8; P < 0.014) in plasma ATP in the same specimens. This increased plasma ATP was highly correlated with a reduction in platelet ATP when analyzed by bivariate regression analysis. Lastly, transmission electron microscopic analysis demonstrated a significant reduction in dense granule number and ratio of dense granule surface area/cell surface area in 3 hr high dose IL-6 incubations. These findings suggests that IL-6 activates platelets in vitro.

Adenosine Triphosphate↗
PubMed1994

Effects of interleukin-2 administration on platelet function in cancer patients.

Platelet function in 16 patients with metastatic renal cell carcinoma and melanoma was studied sequentially over the first 96 hr of treatment with moderate and high-dose interleukin-2 (IL-2). During the first 96 hr of therapy, an increased ex vivo platelet maximal aggregation (MA) response to ADP, epinephrine, and arachidonic acid was paralleled by a decrease in the peripheral platelet count. Plasma specimens from patients receiving the moderate dose schedule showed a significant IL-2 induced secretory response of the platelet alpha-granule components beta-thromboglobulin (BTG) and platelet factor 4 (PF4) and the eicosanoid thromboxane B2 (TBX2) as measured by RIA. The increase in TXB2 was highly correlated with MA when analyzed by bivariate regression analysis, whereas the addition of PF4 to TXB2 in a multiple regression analysis further increased their correlation to MA. The observed decrease in peripheral platelet count correlated significantly with MA and PF4 secretion. High-dose IL-2-treated patients showed a statistically significant increase in the percentage of large platelets exceeding 12 fl in diameter and platelet responsiveness to hypotonic shock. These observations suggest that IL-2 therapy results in a reduced peripheral platelet pool, with an increased proportion of the remaining pool of platelets larger, more viable, and activated.

Adult↗
PubMed1994

Platelet activation induced by interleukin-6: evidence for a mechanism involving arachidonic acid metabolism.

The effect of IL-6 on in vitro platelet function was investigated. Platelet-rich plasma (PRP) incubated with IL-6 showed a dose dependent enhancement of agonist induced maximum aggregation (AIMA) and secretion of thromboxane B2 (TXB2) as measured by RIA, in short term incubations. Dazoxiben (0.2 to 160 microM) pretreated PRP incubated with IL-6 and aggregated with ionophore A23187, showed a dose dependent inhibition of TXB2 secretion concomitant with a dose dependent abrogation of IL-6's enhancement of AIMA. A similar abrogation of AIMA was observed when these experiments were repeated using indomethacin. Further, PRP incubated with IL-6 showed a dose dependent increase in TXB2 and BTG secretion as measured by RIA and an increased incorporation of actin binding protein, talin, and myosin into the cytoskeletal core (triton insoluble residue) as shown by SDS-PAGE. The integrin glycoprotein IIIa (GPIIIa) was also observed to be retained into the cytoskeleton by immunoblot. These results suggest that IL-6 activates platelets in vitro and enhances AIMA via a mechanism involving arachidonic acid metabolism.

Adenosine Diphosphate↗
PubMed1990

Quantitation of oncogene products by computer-assisted image analysis and flow cytometry.

The use of antibodies permits the study of oncogene product expression in cells and tissues. However, quantitation of the levels of expression in immunohistochemical preparations is beset by difficulties, and the available scoring system provide semiquantitative data at best. Here we describe the use of computer-assisted image analysis for determination of oncoprotein levels in a model system and compare the results with those generated by flow cytometric analysis. The oncogene products measured are located in the nucleus (c-myc p62 and c-fos p55), the inner surface of the membrane (c-ras p21), and both sides of the membrane (c-erbB-2 p185). In each instance, both analytic modalities yielded concordant results. Our data indicate that computer-assisted image analysis is a useful tool for quantitating cell components in immunohistochemical preparations.

Breast Neoplasms↗
PubMed1978

Erythrocyte actin and spectrin. Interactions with muscle contractile and regulatory proteins.

Actin and spectrin were isolated from washed red blood cell membranes. Spectrin bound and polymerized erythrocyte actin in the absence of potassium. Spectrin coated into polystyrene latex particles bound 8--9 mol of erythrocyte actin per mol of spectrin when actin was in its depolymerized state. Spectrin enhanced the interaction of erythrocyte actin with muscle myosin as manifested by changes in Mg2+-ATPase activity. A similar enhancement also was observed with muscle alpha-actinin while muscle tropomyosin abolished these effects. The data suggest that spectrin may play the role of polymerizing factor as well as the anchoring site for erythrocyte actin just as alpha-actinin is the anchoring site for actin filaments in muscle and other non-muscle cells.

Actinin↗
PubMed1977

Immunological identification of complex proteins resolved by sodium dodecyl sulfate polyacrylamide disc gel electrophoresis.

Immunological identification of an antigen resolved from a protein complex by sodium dodecyl sulfate polyacrylamide gel electrophoresis has been attained. The identification is based on the formation of immunoprecipitin lines after the antigen diffuses laterally from acrylamide gel transverse slices into a surrounding agarose gel. This technique was designed for study of contractile and regulatory protein complexes of non-muscle cells where the scarcity of tissue precludes easy purification or high yield of muscle-like proteins. It complements double-gel immunodiffusion or immunoelectrophoresis and its use may be extended to other protein complexes.

Actinin↗
PubMed1977

alpha-Actinin and tropomyosin interactions with a hybrid complex of erythrocyte-actin and muscle-myosin.

alpha-Actinin isolated from dog muscle was used to incite antibodies in rabbits, Antibodies, purified by affinity chromatography on CNBr-Sepharose coupled with alpha-actinin and then ferritin-labeled were found to localize on the Z disc of muscle sarcomeres. Molecules of alpha-actinin as an adsorbed monolayer on the surface of polystyrene Lytron particles could bind muscle-actin and tropomyosin from solution. Both the ATPase activity and superprecipitation of an erythrocyte-actin and muscle-myosin hybrid actomyosin complex were altered by alpha-actinin, while tropomyosin diminished these alpha-actinin effects. The binding properties of alpha-actinin are consistent with those of an anchoring protein for microfilaments in nonmuscle cells.

Actinin↗
PubMed1975

Functional changes in platelets during extracorporeal circulation.

An in vitro trauma test was conducted to determine the effects of extracorporeal circulation on platelet count and function. Fresh human blood was circulated in two identical in vitro circuits for six hours at a rate of 500 ml per minute (500 recirculations). One circuit included a G.E.--Peirce membrane lung and the other was a control. Platelet aggregation induced by adenosine diphosphate (ADP), epinephrine, or collagen was studied before and after six hours of perfusion. No important drop in platelet count occurred in the control circuit (Control-C) following bypass, but there was a 20% drop for the lung circuit (Lung-C). Platelet aggregation was reduced by about 30% for the control circuit and 65% for the lung circuit. The large decrease in platelet function accompanied by only a moderate decrease in platelet count is discussed in terms of loss of the youngest and most active platelets, platelet inhibition due to ADP released by red blood cell lysis, and platelet trauma.

Adenosine Diphosphate↗
PubMed1968

Actomyosin-like protein isolated from mammalian brain.

A protein with characteristics similar to actomyosin has been isolated from whole brain of rat and cat. It is soluble in 0.6 molar potassium chloride and insoluble in 0.1 molar potassium chloride. It superprecipitates with magnesium ions and adenosine triphosphate. It has adenosine triphosphatase activity stimulated by either magnesium or calcium ions. Both superprecipitation and adenosine triphosphatase activity are inhibited by p-chloromercuribenzoate and Mersalyl but not by ouabain.

Adenosine Triphosphatases↗