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Biomedical subjects

A Falanga

Publications and source records attributed to A Falanga.

69 records · Page 4Linked to original sources
PubMed1986

Vitamin K-dependent procoagulant in cancer cells: a potential target for the antimetastatic effect of warfarin?

Anticoagulants of the coumarin type have long been reported to inhibit metastasis growth in experimental animals; however, the mechanisms of such effects has not been clarified. Systemic anticoagulation per se does not appear to account completely for such metastasis growth depression. More recent information gathered on a cell procoagulant activity, which is vitamin K-dependent, could probably supply a fresh insight into this problem. Indeed, vitamin K deficiency induced either dietarily or pharmacologically by warfarin, does inhibit the activity of a cysteine protease with direct factor-X-activating properties. This protease is only present in warfarin-sensitive tumors. The correlation of this activity with cancer cell invasiveness is supported by experimental data in metastatic variants and, lately, also by the observation of markedly higher cancer procoagulant activity in extracts from metastases than from primary human melanomas.

Animals↗
PubMed1986

Cancer procoagulant in human tumor cells: evidence from melanoma patients.

It has repeatedly been proposed that fibrin plays a role in tumor growth and metastasis. Among tumor cell products or activities which may promote clot formation, cancer procoagulant (CP), a direct activator of coagulation factor X, has been suggested to be selectively associated with the malignant phenotype. We report here the enzymatic and immunological identification of this cysteine proteinase procoagulant in extracts and cells from human melanoma. CP activity was independent of both the intrinsic and extrinsic pathways of blood coagulation, using factor IX and factor VII deficient plasmas, and was inhibited by the cysteine proteinase inhibitors iodoacetamide and HgCl2. CP activity was detectable in extracts and cell suspensions from all 32 patients studied and was higher in extracts from metastases (14.8 +/- 3.9 units/mg protein) than from the primary tumors (3.7 +/- 1.0 units/mg protein). CP activity was not affected by an anti-apoprotein III antibody or by concanavalin A, a known inhibitor of thromboplastin. In contrast, no CP activity or antigen was detected in extracts from six benign melanocytic lesions. The procoagulant activity was dependent on factor VII and was inhibited by anti-apoprotein III antibody and by concanavalin A, properties that suggest that the procoagulant was tissue thromboplastin. These data indicate that CP can be expressed by human tumor cells and that, among melanotic lesions, its presence is associated with the malignant phenotype and its activity is particularly high in metastatic cells.

Adolescent↗
PubMed1985

Isolation and characterization of cancer procoagulant: a cysteine proteinase from malignant tissue.

Cancer procoagulant, a proteolytic procoagulant enzyme, has been purified from rabbit V2 carcinoma extracts by two procedures. In the first, the protein was purified by benzamidine--Sepharose affinity chromatography, gel filtration chromatography, and phenyl-Sepharose hydrophobic chromatography. Antiserum was raised against the purified protein and was used to prepare an immunoadsorbent column. In the second, tumor extracts were purified by immunoaffinity chromatography followed by p-(chloromercuri)benzoate affinity chromatography. The second procedure was substantially quicker and easier. The final product of both procedures was homogeneous on the basis of analytical sodium dodecyl sulfate--polyacrylamide gel electrophoresis and isoelectric focusing. The molecular weight was 68 000 and the isoelectric point 4.8. The proteinase activity of cancer procoagulant directly activated factor X, in the absence of factor VII, and was inhibited by 1 mM iodoacetamide and 0.1 mM mercury which are classic cysteine proteinase inhibitors. A carbohydrate analysis showed less than 1 mol of hexose or sialic acid/mol of protein. The amino acid analysis showed that serine (19.1%), glycine (18.77%), and glutamic acid (12.5%) were the prevalent amino acids. The amino acid composition of cancer procoagulant was substantially different than other known factor X activating proteinases or other cysteine proteinases including cathepsin B.

Amino Acids↗
PubMed1985

Comparison of properties of cancer procoagulant and human amnion-chorion procoagulant.

Cysteine proteinases that initiate coagulation in the absence of factor VII have been isolated from rabbit V2 carcinoma and from human amnion-chorion. Many of their biochemical properties, including a molecular weight of 68 000 and inhibition by iodoacetamide and mercury, are the same. In the paper we compare the isoelectric point, the amino acid composition and the carbohydrate content of human amnion-chorion procoagulant and cancer procoagulant. With the exception of minor differences in the amino acid composition, attributable in part to differences in species, the two proteins are closely homologous.

Amino Acids↗
PubMed1985

Plasma lipoproteins and lipoprotein lipase in young diabetics with and without ketonuria.

Plasma lipoprotein and lipoprotein lipase activity have been evaluated in young diabetics with and without ketonuria and in healthy controls of the same age. Fifteen (age range 7-23 years) newly detected diabetics (8 with ketonuria, 7 non ketonuric) have been examined before starting the treatment. Five healthy medical students (age range 19-21 years) have also been studied. Both ketotic and non ketotic patients showed an impaired insulin and C-peptide response to the glucose load in comparison to controls. Ketotic patients had low lipoprotein lipase activity (p less than 0.01) and high density lipoprotein (p less than 0.01); total plasma Triglycerides and VLDL Triglyceride and Cholesterol were higher than in controls. Plasma Triglyceride and VLDL Triglyceride and Cholesterol were inversely related to lipoprotein lipase activity. Low lipoprotein lipase activity, from adipose tissue and muscle, has been found to be associated with hypertriglyceridemia and reduced HDL Cholesterol in young diabetic patients with ketonuria.

Adolescent↗
PubMed1985

Cysteine proteinase procoagulant from amnion-chorion.

Various coagulation abnormalities are associated with pregnancy. Several investigators have suggested that there may be a unique procoagulant associated with amniotic tissue and fluid. We identified a cysteine proteinase from malignant tissue, cancer procoagulant, and had reason to believe a similar proteinase may be present in amniotic tissue. Amniotic fluid and extracts of amnion-chorion were purified by immunoaffinity chromatography with an antibody that was developed to cancer procoagulant antigen. The purified amnion-chorion procoagulant initiated clotting in normal and factor VII-deficient citrated human plasma and directly activated pure human factor X in a two-stage clotting assay. It was inhibited by 1 mmol/L of iodoacetamide and 0.1 mmol/L of HgCl2, and the procoagulant activity was activated by 10 mmol/L of KCN; these are classic properties of cysteine proteinases. The pure amnion-chorion procoagulant had the same mol wt and immunologic determinants as cancer procoagulant from rabbit V2 carcinoma, as determined by crossed immunodiffusion, suggesting that the same or very similar proteins were associated with both tissues. Thus, this procoagulant may be derived from both undifferentiated and dedifferentiated cells.

Amnion↗
PubMed1984

SQ 22536, an adenylate-cyclase inhibitor, prevents the antiplatelet effect of dazoxiben, a thromboxane-synthetase inhibitor.

This study shows that dazoxiben, a selective inhibitor of thromboxane A2-synthetase in human platelets, inhibited arachidonic acid-induced platelet aggregation in platelet-rich plasma samples from four out of 16 healthy volunteers. In these four "responder" samples, the anti-aggregating effect of dazoxiben was prevented by the compound SQ 22536, a 9-substituted adenine analogue, endowed with an inhibitory activity on adenylate-cyclase. The compound SQ 22536 also counteracted the antiaggregating effect of prostaglandin D2, a known activator of platelet adenylate-cyclase. When platelet thromboxane A2-synthetase was blocked by dazoxiben, a marked increase of prostaglandin D2 was concomitantly observed both in "responder" and "non responder" samples. The compound SQ 22536 blunted the increase in platelet cAMP caused by either dazoxiben and sodium arachidonate or prostaglandin D2. It is suggested that the antiaggregating effect of dazoxiben is mediated by newly synthesized prostaglandin D2. The latter acts by stimulating adenylate-cyclase and increasing cAMP levels. The compound SQ 22536 prevents both phenomena. In "non responder" samples some factors--still to be defined--might counteract similarly to the compound SQ 22536 the antiaggregating activity of PGD2.

Adenine↗
PubMed1984

The effect of vitamin E or selenium on the oxidant-antioxidant balance in rats.

Vitamin E and selenium are two components which contribute to the antioxidant potential of plasma and tissues. In the present study we aimed to define the type of tissue toxicity deriving from chronic deficiency of either vitamin E or selenium and to evaluate the reliability of peripheral markers of tissue toxicity in these conditions. We studied rats fed a vitamin E or selenium-deficient diet for 3 or 7 months and a selenium-supplemented diet. The effectiveness of the dietary treatment was confirmed by measuring vitamin E and selenium in plasma. Heart and kidney malondialdehyde (MDA), a typical product of lipid peroxidation, was significantly increased after the 3-month diet in both vitamin E- and selenium-deficient rats. The iron-binding capacity of plasma, an activity ascribed to plasma transferrin, was reduced in selenium-deficient and increased in selenium-supplemented animals. In red cells globular resistance (resistance to osmotic haemolysis) was low in vitamin E- and selenium-deficient, but high in selenium-supplemented animals. Glutathione peroxidase was also increased in selenium-supplemented rats. Platelet count did not differ from controls in any of the three conditions studied. Platelet MDA formation induced by arachidonic acid was raised in both selenium-deficient and, particularly, vitamin E-deficient groups. This can be regarded as a peripheral marker of reduced antioxidant defence at tissue level.

Animals↗
PubMed1984

Pharmacologic inhibition of thromboxane synthetase and platelet aggregation: modulatory role of cyclooxygenase products.

Dazoxiben , an imidazole-derived selective inhibitor of thromboxane A2 (TxA2) synthetase, prevented TxB2 synthesis in vitro in platelet-rich plasma from 16 normal subjects. Inhibition of TxB2 synthesis was accompanied by increased generation of PGE2, PGF2 alpha, and PGD2, as shown by radioimmunoassay, thin-layer radiochromatography, and high-resolution gas chromatography-mass spectrometry. Even at dazoxiben concentrations (40-80 microM) above those inhibiting TxB2 synthesis, platelet aggregation induced by threshold concentrations of arachidonic acid was inhibited in only 4 of 16 subjects, referred to as responders. The remaining 12 individuals were defined as nonresponders. The aggregating effect of arachidonic acid and of the prostaglandin-endoperoxide analog U-46619 was potentiated by PGE2 and prevented by PGD2 at concentrations within the range of those detected in dazoxiben -treated platelet-rich plasma. The antiaggregating effect of dazoxiben was counteracted by PGE2 (in responders) and was potentiated by PGD2 (in nonresponders). Platelets from responders and nonresponders did not differ in the amount of immunoreactive PGE2 material or in their sensitivity to U-46619 or PGD2. It is concluded that inhibition of thromboxane synthetase does not per se prevent platelet aggregation. The functional result of thromboxane suppression appears to be modulated by an interplay of the prostaglandin-endoperoxides, PGE2 and PGD2, which are formed in excess.

Adult↗
PubMed1983

Platelet thromboxane synthetase inhibitors with low doses of aspirin: possible resolution of the "aspirin dilemma".

Selective pharmacological inhibition of thromboxane A2 synthesis did not prevent arachidonate-induced aggregation of human platelets in vitro. Prevention was instead achieved by a combination of thromboxane A2 inhibitors with low concentrations of aspirin. The latter partially reduced the proaggregatory cyclooxygenase products that accumulated when thromboxane A2 synthesis was blocked. The aspirin concentrations did not affect per se either platelet aggregation or prostacyclin synthesis in cultured human endothelial cells. The combination of thromboxane synthetase inhibitors with low doses of aspirin may offer greater antithrombotic potential than either drug alone.

Aspirin↗
PubMed1983

Unbalanced plasma control of TxA2 and PGI2 synthesis in vitamin E-deficient rats.

Factors contributing to the antioxidant power of plasma may play a role in the control of arachidonic acid (AA) metabolism. The purpose of this study was to evaluate the possible effects of vitamin E deficiency on platelet and vascular prostaglandin synthesis. CD-COBS male rats were fed for 7 mo a diet containing either 1 or 75 mg/kg vitamin E. At the end of this period, serum levels of vitamin E were 0.4 +/- 0.1 and 10 +/- 0.6 micrograms/ml in the two groups, respectively. Malondialdehyde (MDA) generation by AA was significantly higher in platelet-rich plasma from vitamin E-deficient rats. Thromboxane B2 (TxB2) in serum from vitamin E-deficient rats increased about 16 times compared with controls, whereas 6-keto-PGF1 alpha levels increased only 3 times. The ratio between TxB2 and 6-keto-PGF1 alpha, increased therefore manyfold in vitamin E-deficient animals. MDA formation and [14C]AA metabolism in washed platelets were similar in the two groups of animals. No significant difference was found in the PGI2 (prostacyclin) antiaggregating activity released from the aortic rings resuspended in buffer. In contrast, the capacity of plasma to stimulate PGI2 activity from "exhausted" aortic rings (prostacyclin-stimulating factor) was significantly reduced in vitamin E-deficient animals. In conclusion, vitamin E deficiency induces an unbalanced plasma regulation of AA metabolism. This results in an excessive production of platelet TxA2 compared with vascular PGI2 generation. On the other hand, vitamin E deficiency does not seem to affect directly the enzymatic pathways of AA metabolism.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Evidence of a warfarin-sensitive cancer procoagulant in V2 carcinoma.

Rabbit V2 carcinoma tissue is the tumor in which cancer procoagulant activity (CP) was first described, purified and identified as a cysteine proteinase able to activate F X directly. In the present study we show that CP of V2 carcinoma extracts is depressed in its biological activity (although the antigen is present) by warfarin treatment. The biochemical basis for this effect is offered by the identification of Vit.K-dependent gamma-carboxylase in the microsomal fraction of the tumor tissue. V2 carcinoma tissue had very low endogenous substrate(s) of tumor carboxylase in basal conditions but this increased threefold after warfarin. The accumulation of endogenous substrate(s) and the depression of the CP activity by warfarin raises the possibility that CP represents at least one of the substrates for gamma-glutamyl carboxylase in this experimental tumor tissue.

Animals↗
PubMedDate not supplied

Effects of dexamethasone on pro-inflammatory cytokine expression, cell growth and maturation during granulocytic differentiation of acute promyelocytic leukemia cells.

In basal conditions, NB4 and HL-60, two acute promyelocytic leukemia cell lines, express high levels of tumor necrosis factor (TNF-alpha) mRNA, whereas they do not synthesize appreciable amounts of the transcripts coding for interleukin-1 beta (IL-1 beta) or interleukin-8 (IL-8). Upon granulocytic differentiation with all-trans retinoic acid (ATRA) or the combination of ATRA and granulocyte-colony-stimulating factor (G-CSF), significant amounts of IL-1 beta and IL-8 mRNAs accumulated in both cell types. These changes in mRNA levels were parallelled by the increased secretion of the two cytokines. Dexamethasone (DEX) had no effect on the induction of IL-1 beta mRNA, while it enhanced the G-CSF-, ATRA- and (ATRA+G-CSF) dependent secretion of the cytokine. In combination with ATRA and G-CSF, the corticosteroid increased the expression of leukocyte alkaline phosphatase, a late marker of granulocytic differentiation.

Alkaline Phosphatase↗