Biomedical subjects

J P Brozna

Publications and source records attributed to J P Brozna.

16 recordsLinked to original sources

PubMed1995

Properties of classic protein kinase C in human small cell lung carcinoma NCI-H345 cells.

Bombesin-like peptides (BLPs) activate protein kinase C (PKC), which leads to proliferation in nonmalignant Swiss 3T3 cells. The purpose of this study was to determine if PKC expression in the classic human small cell lung carcinoma NCI-H345 cell line, which has an autocrine growth loop involving BLPs, exhibited unique properties that could result in malignant behavior. PKC activity and phorbol dibutyrate binding in NCI-H345 cells had properties similar to other reports. PKC activity in the cytosolic fraction increased to 100% as cells proliferated through lag, log, and plateau growth states. However, during the first 3 days after plating (lag growth state), 40-50% of the PKC activity was membrane associated, indicating a substantial portion in an activated form, possibly a result of BLP autocrine stimulation. NCI-H345 cells expressed the PKC isoenzymes alpha, beta, delta, sigma, and eta, but not gamma or epsilon, a pattern different from Swiss 3T3 cells or normal brain. further characterization of the Ca2+/phospholipid-dependent (classic) PKC isoenzymes, alpha and beta, showed that PKC beta was predominantly cytosolic (80%) as expected, but PKC alpha was primarily membrane associated (80-90%). Exposure of NCI-H345 cells to 200 nm phorbol 12-myristyl 13-acetate rapidly (within 2 min) decreased cytosolic PKC activity, with no change in the particulate activity, but did not alter [3H]-thymidine incorporation or subcellular distribution of PKC alpha or beta by Western blot. These results suggest altered PKC regulation in human small cell lung carcinoma NCI-H345 cells, which could contribute to their malignant behavior.

3T3 Cells↗

PubMed1994

Staurosporine blocks down-regulation of monocyte-associated tissue factor.

Inflammatory agents including bacterial endotoxin (LPS) and low concentrations of phorbol myristate acetate (PMA) stimulate human peripheral blood monocytes to transiently express tissue factor procoagulant activity. Concentrations of PMA that cause the cytosol-to-membrane translocation of protein kinase C (PKC) (10(-9)-10(-7) M) induce a rapid decrease in monocyte tissue factor activity. Staurosporine, an inhibitor of protein kinase C, enhances the stimulatory effect of low concentrations of PMA on monocyte expression of tissue factor activity and blocks suppression of tissue factor activity at high PMA concentrations. Furthermore, staurosporine prolongs LPS-induced tissue factor expression in monocytes. These results suggest that protein kinases modulate tissue factor activity in human monocytes by regulating both induction and down-regulation.

Alkaloids↗

PubMed1993

The role of tissue factor in the production of thrombin.

Tissue factor is now widely accepted to be the major physiological initiator of blood coagulation. The importance of this protein to normal haemostasis may be inferred from the clinical effects of factor VII deficiency and by the fact that congenital tissue factor deficiency has not been described. Tissue factor is a single polypeptide with an established amino acid sequence that may be divided into cytoplasmic, extracellular and transmembrane regions. There are no close structural similarities with other proteins although tissue factor may be a member of the cytokine receptor family. This paper reviews current knowledge of the role of tissue factor in the production of thrombin with particular reference to its expression, location, control and relevance to haemostasis.

Amino Acid Sequence↗

PubMed1991

Monocyte responses to sulfatide from Mycobacterium tuberculosis: inhibition of priming for enhanced release of superoxide, associated with increased secretion of interleukin-1 and tumor necrosis factor alpha, and altered protein phosphorylation.

In monocytes, sulfatide, a lipid from Mycobacterium tuberculosis, blocked priming for enhanced release of superoxide (O2-) by the macrophage activating factors lipopolysaccharide, gamma interferon, interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), and muramyl dipeptide. Sulfatide, in the presence of lipopolysaccharide, also caused increased secretion of IL-1 beta and TNF-alpha into monocyte culture medium. Sulfatide altered the pattern of phosphorylation of monocyte proteins. Cell lysates prepared from monocytes treated with sulfatide showed decreased activity of protein kinase C, but sulfatide did not directly inhibit protein kinase C activity when added to lysates. A known inhibitor of protein kinase C, staurosporine, also inhibited O2- release and caused increased secretion of IL-1 beta. Thus, sulfatide appeared to indirectly affect protein kinase C, implicating protein kinase C as part of the mechanism of priming. Because sulfatide blocked priming for enhanced release of O2-, which could interfere with monocyte bactericidal activity, while causing enhanced secretion of IL-1 beta and TNF-alpha, which could promote formation of granulomata, sulfatide might be an important factor in the pathogenesis of M. tuberculosis.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1990

Dipyridamole inhibits O2- release and expression of tissue factor activity by peripheral blood monocytes stimulated with lipopolysaccharide.

Monocytes can be induced to synthesize and express tissue factor procoagulant activity. They can also be stimulated to release a broad spectrum of inflammatory agents including superoxide anion (O2-) that are thought to contribute to the pathogenesis of inflammatory diseases. Dipyridamole, an inhibitor of platelet aggregation blocks the lipopolysaccharide (LPS)-induced increase in monocyte-associated tissue factor activity and phorbol myristate acetate (PMA) stimulated O2- release from monocytes and polymorphonuclear leukocytes (PMN). Dipyridamole inhibition of O2- release can be reversed by increased glucose in the culture media, whereas dipyridamole inhibition of tissue factor can not be reversed by increased glucose in the culture media. These results reveal that dipyridamole influences monocytes by at least two distinct mechanisms. Further, it may serve as an anti-thrombotic agent by virtue of its effect on both platelet aggregation and monocyte tissue factor activity.

Biological Transport↗

PubMed1990

Shwartzman reaction.

The local and generalized Shwartzman reactions are models of thrombohemorrhagic skin necrosis and DIC, respectively. An intravenous preparatory injection of endotoxin followed by an intradermal injection of endotoxin 24 hours later elicits a thrombohemorrhagic lesion only at the site of intradermal injection of endotoxin in the local Shwartzman reaction. Two intravenous injections of endotoxin spaced 24 hours apart induced a systemic generalized Shwartzman reaction characterized by coagulopathy, petechial hemorrhages, microthrombi, and decreased circulating platelets similar to DIC. Of particular interest is the observation that thrombohemorrhagic lesions of the Shwartzman reaction only develop at sites of intradermal injections of endotoxin. Microthrombi composed of platelets and leukocytes only adhere or accumulate in dermal vessels after an intradermal injection of endotoxin. Prior to the endotoxin injection, biopsies of skin show normal vessels without microthrombi or significant inflammation. Since endothelial cells line the small vessels in the dermis, where a Shwartzman reaction appears to be initiated, it is likely that endothelial cells are important for initiating a local Shwartzman reaction. IL-1 and TNF can substitute for the intradermal injection of endotoxin in the local Shwartzman reaction, induce endothelial cells to become thrombogenic, and can induce the expression of cell adhesion molecules on endothelial cells making endothelial cells more sticky for leukocytes. These observations suggest that endothelial cells play a central role in the local Shwartzman reaction and may be important in understanding diseases associated with thrombohemorrhagic skin necrosis.

Animals↗

PubMed1990

Cellular regulation of tissue factor.

Tissue factor is the initiator of the extrinsic coagulation pathway and is an important regulator of haemostasis. Tissue factor is constitutively expressed in numerous cells and tissues, and can be induced in monocytes and endothelial cells by different inflammatory agents. Lymphocytes and serum factors can modulate the expression of tissue factor in monocytes. The regulation of tissue factor expression in monocytes appears to be different from that in endothelial cells. Phorbol myristate acetate can inhibit as well as induce tissue factor activity in monocytes, whereas phorbol myristate acetate only induces the expression of tissue factor in endothelial cells. Tissue factor expression in monocytes from patients with infections is not always associated with DIC. The extrinsic pathway inhibitor may play a role in the development of DIC in patients with sepsis. Deposition of extravascular fibrin may be an important determinant of tissue injury.

Amino Acid Sequence↗

PubMed1988

Activation of the respiratory burst in macrophages. Phosphorylation specifically associated with Fc receptor-mediated stimulation.

Inflammatory macrophages elicited from the peritoneal cavity of mice injected with endotoxin can avidly ingest E opsonized with IgG antibody (EIgG) or with IgM antibody and C (EIgMC). However, only ingestion of EIgG is associated with activation of the respiratory burst and release of superoxide anion. We compared the endogenous phosphorylation of proteins from macrophages stimulated by interaction with EIgG or EIgMC on the premise that proteins phosphorylated after stimulation by EIgG but not EIgMC could play a role in activating the enzyme (oxidase) responsible for the respiratory burst. Proteins were separated by one-dimensional and two-dimensional electrophoresis in polyacrylamide gels. We found that proteins with approximate Mr of 20 kDa, 23 kDa, 46 kDa, 48 kDa (three proteins), 67 kDa, and 130 kDa were more heavily phosphorylated after EIgG stimulation than after EIgMC stimulation. Exposure to PMA, which activates the respiratory burst oxidase, induced phosphorylation of the 23-kDa, 48-kDa group, and 130-kDa proteins that were phosphorylated after stimulation by EIgG. Activity of protein kinase C was found to be significantly increased in the particulate fraction of macrophages stimulated by EIgG but not in the particulate fraction of EIgMC-stimulated cells. These data are compatible with the hypotheses that phosphorylation of specific cellular proteins, especially with a Mr of approximately 48 kDa, is involved in activation of the respiratory burst oxidase, and that function of protein kinase C also plays a part in this activation process.

Animals↗

PubMed1988

Inhibition of macrophage priming by sulfatide from Mycobacterium tuberculosis.

Sulfatide from the outer surface of Mycobacterium tuberculosis blocked priming in cultured human monocytes. Monocytes were primed in vitro with either lipopolysaccharide (LPS) or interferon-gamma. Primed monocytes released increased amounts of superoxide anion (O2-) when stimulated with formyl-methionyl-leucyl-phenylalanine or with phorbol myristate acetate. Primed monocytes also showed increased phagocytosis of sheep erythrocytes and increased release of interleukin 1. When primed monocytes were treated with 10 micrograms/ml of sulfatide, these enhanced functions, characteristic of primed monocytes, returned to levels found in unprimed monocytes. (With respect to these functions and others, monocytes or macrophages primed in vitro by exposure to LPS or interferon-gamma resemble macrophages activated in vivo by infection. In vivo, activated macrophages provide non-specific resistance to infection). Inhibition of priming by sulfatide could be detected within 10 min, but maximum effect of sulfatide required 3 to 5 hr. Sulfatide had no effect on O2- release, if it was added after the cells had been stimulated by PMA, suggesting that sulfatide did not inhibit enzymes involved in formation of O2-, but rather that sulfatide inhibited priming. Increasing the amounts of LPS or interferon-gamma did not counteract the effects of sulfatide. Sulfatide did cause monocytes to release some prostaglandin E2 (less than 1 nM), but the amount was not sufficient to inhibit monocyte functions. The effect of sulfatide was not blocked by indomethacin. Other sulfated compounds and other products of mycobacteria did not produce the sulfatide effect. We conclude that M. tuberculosis has on its outer surface a chemical that directly interferes with monocyte priming. In vivo, M. tuberculosis might use sulfatide to block macrophage activation and thereby resist being killed by macrophages.

Dinoprostone↗

PubMed1988

Monocyte-associated tissue factor is suppressed by phorbol myristate acetate.

The monocyte is the only normal circulating cell type capable of initiating blood coagulation through the expression of tissue factor. Recently isolated peripheral blood monocytes that contain no demonstrable tissue factor activity can be induced to express tissue factor activity by a number of stimulatory agents. Monocyte-associated tissue factor activity transiently increases in response to adherence to tissue culture plates and, consistent with other reports, markedly increases after the isolated monocytes are treated with endotoxin. Phorbol myristate acetate (PMA) induced an increase in tissue factor activity at low doses (10(-11) to 10(-12) mol/L). Conversely, concentrations of PMA that stimulate release of oxygen metabolites or that cause the cytosol-to-membrane translocation of protein kinase C (PKC) (10(-9) to 10(-7) mol/L) resulted in a rapid decrease in both adherence-induced and endotoxin-induced monocyte tissue factor activity. The effects of PMA on monocytes were time- and dose-dependent with respect to PKC translocation, release of oxygen metabolites, and changes in tissue factor activity. Immunofluorescent staining of monocytes with monoclonal antibody (MoAb) HTF1-7B8, directed against human tissue factor, revealed that tissue factor antigen was induced concurrently with tissue factor activity by adherence and endotoxin and that tissue factor antigen decreased after PMA stimulation.

Cells, Cultured↗

PubMed1985

Filiform polyposis: an unusual complication of inflammatory bowel disease.

Filiform polyposis is an unusual form of inflammatory polyposis which complicates inflammatory bowel disease. Recognition of this variant is important in that its radiographic and endoscopic picture may mimic villous adenoma or adenocarcinoma. Filiform polyposis may precipitate obstruction by stricture formation or give rise to major hemorrhage. We report five patients with inflammatory bowel disease complicated by asymptomatic filiform polyposis to emphasize the pathology of this lesion. We also review the literature regarding this topic.

Adult↗

PubMed1979

Suppression of acute and chronic inflammation in tumor-bearing rats.

Both acute and chronic cellular inflammatory reactions were suppressed in rats bearing malignant tumors. Inhibition of the acute inflammatory reactions was demonstrated in immune complex-induced vasculitis and in the accumulation of leukocytes in subcutaneously implanted polyvinyl sponges. Suppression of chronic inflammatory reactions was demonstrated in delayed type hypersensitivity skin reactions. In spite of these suppressed reactions, dermal reactivity to vasopermeability mediators was not diminished. Neither serum complement levels nor numbers of circulating leukocytes were depressed in animals with tumors. Suppression of inflammatory reactions was paralleled by a leukotactic defect which involved both neutrophils and monocytes. This defect could be ascribed to an abnormality in the serum that rendered both cell types leukotactically defective.

Animals↗

PubMed1979

In vitro and in vivo production of chemotactic inhibitors by tumor cells.

The ascites fluid or peritoneal washings of DBA/2 mice bearing the P815 mastocytoma have been found to contain a chemotactic factor inactivator (CFI) which inactivates the bacterial chemotactic factor as well as the chemotactic activity associated with the C3 and C5 fragments when assayed on rabbit neutrophils. The amount of CFI is proportional to the number of tumor cells in the peritoneal exudate. The inactivator is also found in tumor cell hemogenates as well as in culture fluid from tumor cells growing in vitro. The activity is heat-labile but is not affected by protease inhibitors. Its molecular weight is greater than 50,000 daltons, based on Sephadex chromatography and sucrose density gradient ultracentrifugation studies. In C57BL/6 mice, which reject the mastocytoma, CFI levels decrease in proportion to the decreasing numbers of tumor cells.

Animals↗

PubMed1977

Chemotactic factor inactivators of human granulocytes.

During phagocytosis, neutrophils release a variety of substances that include activators and inactivators of chemotactic factors. It is generally considered that these represent hydrolytic enzymes. Elastase and cathepsin G, major proteases released from lysosomal granules during phagocytosis, contain broad hydrolytic activity. This study examined granule elastase and cathepsin G for their role as inactivators of chemotactic factors. Elastase and cathepsin G were purified from human neutrophils by Trasylol-Sepharose and CM-cellulose chromatography. Small amounts (approximately equal to 3 microgram, 1 muM) of elastase and cathepsin G, comparable to quantities released by 10(6) neutrophils during phagocytosis, completely inactivated the C5 chemotactic factor generated in human serum. Larger concentrations were needed to inactivate the C3 chemotactic factor, and when the bacterial chemotactic factor from Escherichia coli was employed, five times more elastase or cathepsin G was ineffective against this chemotactic factor. Supernatant fluid from human neutrophils that had ingested complement-coated zymosan particles contained elastase and cathepsin G and had inactivator activity for both the C5 chemotactic fragment and the bacterial factor. A specific inhibitor of elastase largely abolished the inactivator activity in the phagocytic supernates that was directed against C5 factor but did not affect the inactivator activity for the bacterial factor. Similar results occurred in studies of granule lysates. These data indicate heterogeneity in the chemotactic factor inactivator activity released by phagocytosing neutrophils. The predominant inactivator activity of the C5 chemotactic fragment is attributable to elastase and cathepsin G.

Cathepsins↗

PubMed1975

Antileukotactic properties of tumor cells.

A chemotactic factor inactivator (CFI) has been found in extracts of Walker and Novikoff tumor cells maintained in rats. The CFI directly inactivates the bacterial chemotactic factor as well as the leukotactic activity (fro both neutrophils and monocytes) associated with C3 and C5 fragments and with culture fluids of lectin-stimulated lymphoid cells. The inactivation of the bacterial chemotactic factor is temperature and pH dependent. Subcellular fractionation procedures indicate that CFI is largely associated with the microsomal and cytosol fractions of tumor cells. CFI activity is also found in rat neutrophils, alveolar macrophages, and in extracts of liver, spleen, and kidney from normal animals. CFI derived from normal tissues also directly inactivates the bacterial chemotactic factor and has the ability to inactivate chemotactic activity associated with C3 and C5 fragments. A feature of the tumor-associated CFI is its presence in ascitic fluids of animals bearing tumor cells and the relative absence of any CFI activity in acute inflammatory exudates. The finding of the tumor-associated CFI may explain, at least in part, the tendency of malignant tumor cells to suppress cellular inflammatory reactions.

Animals↗

PubMedDate not supplied

Epithelial-myoepithelial carcinoma of salivary gland with metastasis to lung: report of a case and review of the literature.

A 63-year-old man was initially seen with multiple pulmonary nodules 14 years after a left parotidectomy for an epithelial-myoepithelial carcinoma of salivary gland. Eight and 18 months after parotidectomy, the patient had local recurrence of his salivary gland tumor. He remained disease-free before being seen with pulmonary nodules, which were evaluated by open lung biopsy. The pathologic features of the pulmonary nodules were identical to the salivary gland tumor resected 14 years earlier. This is the fourth reported case of epithelial-myoepithelial carcinoma of salivary gland metastasizing to a distant site.

Adenocarcinoma↗