The identification and characterization of fusogenic domains in herpes virus glycoprotein B molecules

The molecular mechanism of entry of herpes viruses requires a multicomponent fusion system. Virus entry and cell-cell fusion of Herpes simplex virus (HSV) requires four glycoproteins: gD, gB and gH/gL. The role of gB remained elusive until recently, when the crystal structure of HSV-1 gB became available. Glycoprotein B homologues represent the most highly conserved group of herpes virus glycoproteins; however, despite the high degree of sequence and structural conservation, differences in post-translational processing are observed for different members of this virus family. Whereas gB of HSV is not proteolytically processed after oligomerization, most other gB homologues are cleaved by a cellular protease into subunits that remain linked through disulfide bonds. Proteolytic cleavage is common for activation of many other viral fusion proteins, so it remains difficult to envisage a common role for different herpes virus gB structures in the fusion mechanism. We selected bovine herpes virus type 1 (BoHV-1) and herpes simplex virus type 1 (HSV-1) as representative viruses expressing cleaved and uncleaved gBs, and have screened their amino acid sequences for regions of highly interfacial hydrophobicity. Synthetic peptides corresponding to such regions were tested for their ability to induce the fusion of large unilamellar vesicles and to inhibit herpes virus infection. These results underline that several regions of the gB protein are involved in the mechanism of membrane interaction.

Dentine removal in the coronal portion of root canals following two preparation techniques

AIM

To measure the root canal area and the reduction of the mesial and buccal/lingual wall thickness at the level of the coronal interference in mesial roots of mandibular molars after instrumentation with a crown-down or a simultaneous root canal preparation technique.

METHODOLOGY

Twenty mesial roots of first mandibular molars with a moderate root canal curvature were embedded in resin and sectioned horizontally at the level of the coronal interference, using a modification of the Bramante technique. After scanning and processing, the sections were reassembled. One root canal of each root was prepared using ProTaper instruments, while Mtwo instruments were used in the other root canal of the same mesial root. After scanning and processing, the data obtained were analysed for two parameters: changes in root canal area after instrumentation (Delta A) and reduction of the mesial and buccal/lingual wall thickness (Delta T). The data were subjected to Student's t-tests for statistical analysis at a significance level of P < 0.05.

RESULTS

No statistically significant differences were found between the two groups with respect to the changes in the areas (Delta A) at the level considered (P = 0.410). No statistically significant differences were noticed between the two groups for dentine thickness (Delta T) of both the mesial wall (P = 0.077) and the buccal or lingual wall (P = 0.171).

CONCLUSIONS

There was no difference between the ProTaper and Mtwo groups for the amount of dentine removed.

Evidence for a role of the membrane-proximal region of herpes simplex virus type 1 glycoprotein H in membrane fusion and virus inhibition

We have identified a putative membrane-interacting domain preceding the transmembrane domain of the Herpes simplex virus type 1 (HSV-1) glycoprotein H (gH). Peptides derived from this region interact strongly with membranes and show a high tendency to partition at the interface. This region is predicted to bind at the membrane interface by adopting an alpha helical structure. Peptides representing either the HSV-1 gH pretransmembrane region or a scrambled control with a different hydrophobic profile at the point of interface have been studied. The peptides derived from this domain of gH induce the fusion of liposomal membranes, adopt helical conformations in membrane mimetic environments and are able to inhibit HSV-1 infectivity. The pretransmembrane region appears to be a common feature in viral fusion proteins of several virus families, and such a feature might be related to their fusogenic function. The identification of membrane-interacting regions capable of modifying the biophysical properties of phospholipid membranes lends weight to the view that such domains might function directly in the fusion process and could facilitate the future development of HSV-1 entry inhibitors.

Metronomic capecitabine in advanced patients with hepatocellular carcinoma (HCC): Preliminary results

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Background: No standard therapies are available for HCC patients (pts) ineligible for curative treatments. HCC has a rich neovasculature and neoangiogenesis is a negative prognostic factor: a high density of microvessels and hyperexpression of VEGF correlates with an increased propensity for invasion and metastatization and with a decreased DFS after resection. High level of circulating endothelial progenitors cells (CEPc) are related with insurgence and progression of HCC. Phase II trials with antiangiogenic agents in monotherapy had a response rate lower than 10% but stable disease (SD) is encouraging ranging between 30 and 60%. Retrospective analysis of standard capecitibine showed a response of 11% and similar SD rate. Experimental data on solid tumors suggest that metronomic CT prolongs inibihition of tumor growth, avoiding CEPc mobilization. Methods: Starting in september 2006, twenty-two patients were started on treatment (19 male; median age 63.7, range 47–82 ). BCLC (Barcelona Consensus Liver Cancer): 5 pts = B; 17 pts = C; Child: 12 pts =A, 8=B, 2=C. 14 pts had portal thrombosis. 15 pts were treated in front line, 7 in second line (4 pts previously treated with Sorafenib and 3 with experimental protocol of CPT-11 HAI; ASCO 2006 Abs 14061 ). The first cycle was carried out with standard capecitabine (2000 mg/sq.mt; 14 over 21 days), followed by metronomic capecitabine (1300 mg) without interruption. To compare the angiogenic role of metronomic capecitabine versus standard administration, VEGF and trombospondine have been dosed at baseline and after the first cycle of standard capecitabine and after one month of metronomic capecitabine. The response has been assessed by CT scan every three months. Results: Five out of 22 patients have been dismissed for toxicity (liver failure) during the standard capecitabine treatment. Among the 17 remaining patients, two have discontinued the treatment due to toxicity (liver failure) during the metronomic treatment and 10 have accomplished at least the first month of metronomic schedule. 6 patients have been evaluated for response: 2 PR (one second line), 3 SD (all in second line), 1 PD (second line). Conclusions: Metronomic capecitabine seems to have a better tolerability than standard schedule and promises good efficacy.

No significant financial relationships to disclose.

Catastrophic relapse of Evans syndrome five years after allogeneic BMT notwithstanding full donor chimerism. Terminal hemolytic-uremic syndrome

A patient with severe Evans syndrome received an allo-BMT from his HLA-identical sister on November, 2000. Full marrow and blood donor chimerism were achieved only after 5 donor lymphocyte infusions (DLI), and coincided with complete clinical remission and disappearence of auto-antibodies. Five years later, hemolytic anemia recurred with rapid increase of serum bilirubin to over 50 mg%: he responded to combined therapy, but died on day +17 from admission of an acute hemolytic uremic syndrome (HUS). All circulating blood cells, including erythrocytes, were 100% donor. Ex vivo cultured and expanded T and B cells from the peripheral blood were also 100% donor. The supernatants from B cell cultures, containing either IgM or IgG, did not react with a panel of erythrocytes. Thus in this typical autoimmune disease with a predominant B cell pathogenesis the donor immune system resulted "innocent of autoimmunity". The persistence of long-lived recipient autoreactive plasma-cell lines in survival niches, still producing autoantibodies, may be hypothesized for this and similar cases. The postulated graft-versus-autoimmunity (GVA) effect was apparently not sufficient to eradicate autoimmunity in this patient.

Venous thromboembolism and cancer: guidelines of the Italian Association of Medical Oncology (AIOM)

Thromboembolic complications represent one of the most important cause of morbidity and mortality in cancer patients. Although several data have been published demonstrating the strong association between cancer and venous thromboembolism (VTE), there is poor perception, among oncologists, of the level of risk of thrombosis and of relevance of managing VTE in these patients. The Associazione Italiana di Oncologia Medica (AIOM) has provided some recommendations to direct clinical practice according to evidence-based data concerning cancer and VTE. In fact, we conducted an extensive literature review (1996-2005) to produce evidence-based recommendations to improve perceptions of the magnitude of this risk among Italian medical and surgical oncologists and alert on the new approaches to prophylaxis and treatment of VTE in cancer patients. Levels of evidence are given according to a five-point rating system, and similarly for each key recommendation a five-point rating system suggests if the evidence is strong and indicate that the benefits do, or do not, outweigh risks and burden.

Blood oxidative status and selectins plasma levels in healthy donors receiving granulocyte-colony stimulating factor

Recombinant human G-CSF (rHuG-CSF) is used for hematopoietic progenitor cells (HPC) mobilization and collection. Activation of polymorphonuclear leukocytes (PMN) is present during rHuG-CSF treatment and is associated with endothelial cell dysfunction and hypercoagulation. We evaluated whether PMN activation by rHuG-CSF may alter the blood oxidative status and subsequently affect the vascular cell function. Fourteen healthy individuals received rHuG-CSF for HPC harvesting. Blood was drawn before starting rHuG-CSF (T0), on the last day of rHuG-CSF (T1) and 1 week after stopping rHuG-CSF (T2). Levels of CD11b, myeloperoxidase (MPO), hydroperoxides, nitric oxide (NO), and soluble endothelium (sES), leukocyte (sLS), and platelet (sPS) selectins were measured. During rHuG-CSF, CD11b, MPO and hydroperoxides significantly increased, while NO levels significantly decreased, compared with T0. At T2 all these markers returned to baseline values. Significant increments of all selectins were observed during rHuG-CSF. At T2 sES and sEP significantly decreased back to pre-treatment values, whereas sLS remained significantly high. These data show that rHuG-CSF induces a transient inflammatory status characterized by circulating activated PMN, which release reactive oxygen species and intracellular proteases, promoting the onset of an abnormal oxidative status. This process may modify the hemostatic balance towards a pro-thrombotic state.

Analysis of synthetic peptides from heptad-repeat domains of herpes simplex virus type 1 glycoproteins H and B

Human herpesviruses enter cells by fusion of their own membrane with a cellular membrane through the concerted action of multiple viral proteins and cellular receptors. Two conserved viral glycoproteins, gB and gH, are required for herpes simplex virus type 1 (HSV-1)-mediated membrane fusion, but little is known of how these proteins cooperate during entry. Both glycoproteins were shown to contain heptad repeat (HR) sequences predicted to form alpha-helical coiled coils, and the inhibitory activity against infection of four sets of synthetic peptides corresponding to HR1 and HR2 of gB and gH was tested. The interactions between these HR peptides were also investigated by circular dichroism, native polyacrylamide-gel electrophoresis and size exclusion high-performance liquid chromatography. gH coiled-coil peptides were more effective than gB coiled-coils peptides in inhibiting virus infectivity. The peptides did not impair fusion when added to cells immediately after infection. In contrast, inhibition of infection was observed, albeit to various extents, when peptides were added to virus before or during inoculation. The results of biophysical analyses were indicative of the existence of an interaction between HR1 and HR2 of gH and suggest that the HRs of gB and gH do not interact with each other.

Fusogenic domains in herpes simplex virus type 1 glycoprotein H

Infection of eukaryotic cells by enveloped viruses requires fusion between the viral envelope and the cellular plasma or endosomal membrane. The actual merging of the two membranes is mediated by viral envelope glycoproteins, which generally contain a highly hydrophobic region termed the fusion peptide. The entry of herpesviruses is mediated by three conserved proteins: glycoproteins B, H (gH), and L. However, how fusion is executed remains unknown. Herpes simplex virus type 1 gH exhibits features typical of viral fusion glycoproteins, and its ectodomain seems to contain a putative internal fusion peptide. Here, we have identified additional internal segments able to interact with membranes and to induce membrane fusion of large unilamellar vesicles. We have applied the hydrophobicity-at-interface scale proposed by Wimley and White (Wimley, W. C., and White, S. H. (1996) Nat. Struct. Biol. 3, 842-848) to identify six hydrophobic stretches within gH with a tendency to partition into the membrane interface, and four of them were able to induce membrane fusion. Experiments in which equimolar mixtures of gH peptides were used indicated that different fusogenic regions may act in a synergistic way. The functional and structural characterization of these segments suggests that herpes simplex virus type 1 gH possesses several fusogenic internal peptides that could participate in the actual fusion event.

Deep vein thrombosis in cancer: the scale of the problem and approaches to management

Patients with cancer have long been recognised to be at high risk of venous thromboembolism (VTE), although the condition remains under diagnosed and under treated in these patients. As a consequence, the morbidity and mortality due to deep venous thrombosis and pulmonary embolism remains unacceptably high in this group. Furthermore, the management of VTE in the presence of malignancy is complex, due both to the effects of the cancer itself and its treatments. Conventional long-term management of VTE involves the use of vitamin K antagonists (VKAs), such as warfarin, to reduce the risk of recurrence. However, this approach is associated with a range of practical difficulties including the need for regular laboratory monitoring, the potential for drug interactions, in addition to the risk of treatment resistance and bleeding in patients with cancer. Recent research indicates that the use of low molecular weight heparin (LMWH) therapy instead of VKAs may be beneficial in these patients. In particular, evidence from a large clinical trial of the LMWH dalteparin indicates that this agent offers an effective alternative to VKAs in the long-term management of VTE, that is free from the practical problems associated with the use of VKAs and without increasing the risk of bleeding.

Extensive screening for occult malignant disease in idiopathic venous thromboembolism: a prospective randomized clinical trial

Patients with symptomatic idiopathic venous thromboembolism and apparently cancer-free have an approximate 10% incidence of subsequent cancer. Apparently cancer-free patients with acute idiopathic venous thromboembolism were randomized to either the strategy of extensive screening for occult cancer or to no further testing. Patients had a 2-year follow-up period. Of the 201 patients, 99 were allocated to the extensive screening group and 102 to the control group. In 13 (13.1%) patients, the extensive screening identified occult cancer. In the extensive screening group, a single (1.0%) malignancy became apparent during follow-up, whereas in the control group a total of 10 (9.8%) malignancies became symptomatic [relative risk, 9.7 (95% CI, 1.3-36.8; P < 0.01]. Overall, malignancies identified in the extensive screening group were at an earlier stage and the mean delay to diagnosis was reduced from 11.6 to 1.0 months (P < 0.001). Cancer-related mortality during the 2 years follow-up period occurred in two (2.0%) of the 99 patients of the extensive screening group vs. four (3.9%) of the 102 control patients [absolute difference, 1.9% (95% CI, -5.5-10.9)]. Although early detection of occult cancers may be associated with improved treatment possibilities, it is uncertain whether this improves the prognosis.

Defibrotide reduces procoagulant activity and increases fibrinolytic properties of endothelial cells

Defibrotide (DF), a polydeoxyribonucleotide with antithrombotic properties, has recently proven effective in patients with severe hepatic veno-occlusive disease (VOD), a life-threatening complication of high-dose chemo/radiotherapy regimens for stem cell transplantation. To understand the mechanism of its beneficial effect, we studied the impact of DF on the expression of tissue factor (TF) and fibrinolytic proteins (PAI-1 and t-PA) on endothelial cells. The in vitro response to DF of two types of human endothelial cells (ECs) of different origins, that is from macrovascular (HUVEC) and microvascular (HMEC-1 cell line) beds, was evaluated in the presence or absence of a proinflammatory stimulus (ie bacterial endotoxin, LPS). The results show that DF was able to significantly reduce the LPS-induced TF expression by HMEC-1, and less prominently by HUVEC. In addition, DF importantly influenced the fibrinolytic properties of both HMEC-1 and HUVEC. Specifically, it dose-dependently counteracted the LPS-induced increase in PAI-1 levels and decrease in t-PA activity expression. It also significantly incremented t-PA antigen in resting EC. Decreasing the procoagulant activity and increasing the fibrinolytic potential of EC favors an anticoagulant phenotype of the endothelium, which may protect from fibrin deposition and vascular occlusion.

Tumor cell prothrombotic properties

Thrombin generation and fibrin formation are constantly determined in patients with malignancy, who are at increased risk of thromboembolic complications. Most importantly, fibrin formation is also involved in the processes of tumor spread and metastasis. Activation of blood coagulation in cancer is a complex phenomenon, involving many different pathways of the hemostatic system and numerous interactions of the tumor cell with other blood cells, including platelet, monocyte and endothelial cell. Tumor cells possess the capacity to interact with all parts of the hemostatic system. They can directly activate the coagulation cascade by producing their own procoagulant factors or they can stimulate the prothrombotic properties of other blood cell components. All of the mechanisms are not entirely understood, however research studies in the last ten years have greatly improved our knowledge of tumor-promoted pro-thrombotic functions.

Disseminated intravascular coagulation in acute leukemia

Malignancy is associated with a "hypercoagulable" state and a high risk for thrombohemorrhagic complications. Clinical complications may range from localized thrombosis to bleeding of varying degrees of severity because of disseminated intravascular coagulation (DIC). Life-threatening bleeding is frequent in acute leukemias, particularly in acute promyelocytic leukemia (APL). Laboratory assessments show profound hemostatic imbalance in this condition, with activation of coagulation, fibrinolysis, and nonspecific proteolysis systems. An important pathogenetic role is attributed to the leukemic cell properties interfering with the hemostatic mechanisms. However, chemotherapy and intercurrent infections also contribute to the bleeding risk in the patient with leukemia. In this article, we will attempt to describe what is currently known about the coagulopathy of acute leukemia, summarize the various aspects of the hemostatic abnormalities underlying this disorder, and revise the principal pathogenetic mechanisms. We will also try to provide information on the current therapeutic tools and recommendations for the management of life-threatening bleeding in this disease. Finally, a special focus will be devoted to the management of this complication in the era of all-trans retinoic acid (ATRA), a drug now indispensable in curing APL that has completely changed the natural history of APL and its coagulation/bleeding syndrome.

Coagulopathy of acute promyelocytic leukemia

Life-threatening bleeding is frequent in acute leukemias, particularly in acute promyelocytic leukemia (APL), a distinct subtype of acute myelogenous leukemia, characterized by the balanced reciprocal translocation between chromosomes 15 and 17. Laboratory assessments show profound hemostatic imbalance compatible with the clinical picture of disseminated intravascular coagulation. Activation of the coagulation system, hyperfibrinolysis and nonspecific proteases activity can be observed in this condition. An important pathogenetic role is attributed to the leukemic cell properties for activating hemostatic mechanisms. This review will summarize what is currently known about the coagulopathy of APL, the principal pathogenetic mechanisms, and the therapeutic tools for the management of this complication. Special attention will be devoted to the new therapy with all-trans retinoic acid, which has completely changed the natural history of APL and APL-related coagulopathy.

Pathogenetic mechanisms of thrombosis in malignancy

The interactions between components of the hemostatic system and cancer cells are multifaceted. Strong clinical evidence is accumulating on the prothrombotic tendency of cancer patients, which is enhanced by anticancer therapy, such as surgery and chemotherapy. The mechanisms of thrombus promotion in malignancy include some general responses of the host to the tumor (acute phase, inflammation, angiogenesis) and specific interactions of tumor cells with the clotting/fibrinolysis systems and with blood (leukocytes, platelets) or vascular cells. It is at present difficult to rank the relative weight of these multiple interactions on the basis of the well-recognized clinical evidence of enhanced thrombotic episodes in tumor patients. In any case, the mechanisms explored so far offer a sound experimental basis for prevention/treatment of thrombosis in tumor patients and leave open the possibility that some antithrombotic strategies may also affect the processes of tumor growth and dissemination.

Molecular basis for the relationship between thrombosis and cancer

Cancer patients are highly susceptible to thromboembolic complications, which some have estimated accounts for a significant percentage of the morbidity and mortality of the disease. Not all of the mechanisms for the production of the hypercoagulable state characteristic of cancer are entirely understood. Those that are known seem to interdigitate the biology of cancer with the major regulatory pathways that mediate blood coagulation, platelet-vessel wall interaction, fibrinolysis and inflammatory cytokine production. In other words, the events responsible for thrombosis in cancer appears to be a result of an over exuberant host response in an attempt to delimit tumor growth. In this brief review, therefore, we attempt to put into the context of tumor growth, angiogenesis and metastasis the current information about the pathogenesis of venous thromboembolism (VTE).

Pathogenesis of Thrombosis in Patients with Malignancy

Cancer cells can contribute to activation of the clotting system by their capacity to produce and release procoagulant/fibrinolytic substances and inflammatory cytokines, and by their interaction with host cells (endothelial, monocytes, platelets, and neutrophils). Moreover, anticancer drugs (chemotherapy/hormone therapy) may greatly affect the risk of thromboembolic complications in cancer patients by similar mechanisms, eg, through the release of procoagulants by tumor cells, through endothelial damage, or stimulation of tissue factor production by host cells. The interactions between cancer/metastatic processes and thrombosis have been reviewed here from the pathogenetic viewpoint. We hope that better knowledge of these pathogenetic pathways will lead to the development of more targeted strategies to prevent thromboembolism in cancer patients.

Polymorphonuclear leukocyte activation and hemostasis in patients with essential thrombocythemia and polycythemia vera

Thrombohemorrhagic complications are a major cause of morbidity and mortality in patients with essential thrombocythemia (ET) and polycythemia vera (PV). The pathogenesis of these complications is not completely clarified. Several studies have described abnormalities of red blood cells and platelets in these patients. However, no studies are available on changes in the polymorphonuclear leukocytes (PMNs), which can play an important role in the activation of the hemostatic system. In patients with ET (n = 37) and PV (n = 34), a series of PMN activation parameters (PMN membrane CD11b and leukocyte alkaline phosphatase [LAP] antigen expression, cellular elastase content, plasma elastase, and myeloperoxidase levels) was evaluated simultaneously with the levels of plasma markers of endothelial damage (thrombomodulin and von Willebrand factor antigen) and hypercoagulation (thrombin-antithrombin complex, prothrombin fragment 1 + 2, and D-dimer). The results show the occurrence of PMN activation in both groups of patients compared with a control group of healthy subjects. An increase in CD11b and LAP expression by PMN membrane was observed, together with a significant increase in cellular elastase content, plasma elastase, and myeloperoxidase levels. In addition, patients had high plasma levels of endothelial and hypercoagulation markers compared with controls. For the first time, these data show that in ET and PV, 2 hematologic conditions that place patients at increased risk for thrombosis, an in vivo leukocyte activation occurs and is associated with laboratory signs of endothelium and coagulation system activation. (Blood. 2000;96:4261-4266)

Mechanisms of hypercoagulation in malignancy and during chemotherapy

Patients with cancer are at increased risk for thromboembolic disease. Commonly they present with abnormalities of one or more circulating markers of haemostatic system activation, underlying a 'hypercoagulable state'. Despite numerous investigations which have identified alterations in all of the haemostatic components (i.e. coagulation, fibrinolysis, endothelium, platelets and monocytes), no firm conclusions have been reached regarding the clinical utility of any of these coagulation markers for predicting thrombosis in cancer patients. The predictive value of one or more of these tests could help to identify safe and effective methods for prophylaxis against thrombotic complications in these patients. Plasma clotting abnormalities are usually exacerbated by chemotherapy. The mechanisms by which the haemostatic system is activated in malignancy (and chemotherapy) are reviewed.

The decanucleotide insertion/deletion polymorphism in the promoter region of the coagulation factor VII gene and the risk of familial myocardial infarction

Recently, an association has been found between factor VII polymorphisms and the risk of familial myocardial infarction. To obtain a thorough evaluation of the influence of factor VII gene on the risk of myocardial infarction, we extended our analysis to the role of a decanucleotide insertion/deletion functional polymorphism (-323 0/10-bp) in the promoter region of factor VII and to possible interactions with the HVR4 intron polymorphism. We performed a case-control study of 176 patients with myocardial infarction, over 45 years, who had a familial history of arterial thrombosis and 227 control subjects without a personal or family history of cardiovascular disease. The frequency of the rare allele of 10 bp was lower in cases (0.14 95% CI, 0.10-0.17) than in controls (0.19 95% CI, 0.16-0.23; chi(2)=4.7, p=0.03). Allowing for Hardy-Weinberg equilibrium in controls and testing for association under restricted maximisation, there was a significant difference in genotype frequency between cases and controls (p=0.02). Carriers of the 10-bp allele had an odds ratio for myocardial infarction of 0.65 (95% CI, 0.37-1.12), in multivariate logistic regression analysis. Combination analysis of -323 0/10-bp and HVR4 polymorphisms shows half reduction in the risk of myocardial infarction in comparison with the reference group for all the other groups, suggesting that there was no additivity between the effect of the 10-bp and the H7 alleles. Our findings suggest that the promoter polymorphism of factor VII gene may influence the risk of familial myocardial infarction.

Pathophysiology of the thrombophilic state in the cancer patient

The "hypercoagulable state" of malignancy is due to a complex interaction of tumor cells and their products with host cells, leading to various degrees of impairment of the normal defense mechanisms that ordinarily protect the host against thrombogenesis. Tumor cells can activate directly the blood clotting cascade and cause thrombosis or can induce procoagulant properties and inhibit anticoagulant properties of vascular endothelial cells, platelets, and monocytes and macrophages. In the setting of the local and systemic effects of cancer (e.g., stasis induced by prolonged bed rest and/or vascular invasion by tumor), together with iatrogenic complications of the treatment of cancer (e.g., the use of central vein catheters and angiopathic chemotherapy), this basic pathophysiology conspires to make cancer perhaps the best example of "acquired thrombophilia." In this brief review, we have attempted to describe what is currently known about the mechanisms for the hypercoagulable state of cancer and provide a summary of the evidence that indicates the many levels of defects in patients with malignancies that predispose them to thrombosis. A better understanding of the pathophysiology of thrombophilia in cancer should provide clinicians with an improved rationale for more aggressive and specific anticoagulant strategies in selected patients.

Neutrophil activation and hemostatic changes in healthy donors receiving granulocyte colony-stimulating factor

Granulocyte colony-stimulating factor (G-CSF) enhances neutrophil functions in vitro and in vivo. It is known that neutrophil-derived products can alter the hemostatic balance. To understand whether polymorphonuclear leukocyte (PMN) activation, measured as PMN degranulation and phenotypical change, may be associated to hemostatic alterations in vivo, we have studied the effect of recombinant human G-CSF (rHuG-CSF) administration on leukocyte parameters and hemostatic variables in healthy donors of hematopoietic progenitor cells (HPCs). Twenty-six consecutive healthy donors receiving 10 micrograms/kg/d rHuG-CSF subcutaneously for 5 to 7 days to mobilize HPCs for allogeneic transplants were included in the study. All of them responded to rHuG-CSF with a significant white blood cell count increase. Blood samples were drawn before therapy on days 2 and 5 and 1 week after stopping rHuG-CSF treatment. The following parameters were evaluated: (1) PMN activation parameters, ie, surface CD11b/CD18 antigen expression, plasma elastase antigen levels and cellular elastase activity; (2) plasma markers of endothelium activation, ie, thrombomodulin (TM) and von Willebrand factor (vWF) antigens; (3) plasma markers of blood coagulation activation, ie, F1+2, TAT complex, D-dimer; and (4) mononuclear cell (MNC) procoagulant activity (PCA) expression. The results show that, after starting rHuG-CSF, an in vivo PMN activation occurred, as demonstrated by the significant increment of surface CD11b/CD18 and plasma elastase antigen levels. Moreover, PMN cellular elastase activity, which was significantly increased at 1 day of treatment, returned to baseline at day 5 to 6, in correspondence with the elastase antigen peak in the circulation. This change was accompanied by a parallel significant increase in plasma levels of the two endothelial and the three coagulation markers. The PCA generated in vitro by unstimulated MNC isolated from rHuG-CSF-treated subjects was not different from that of control cells from untreated subjects. However, endotoxin-stimulated MNC isolated from on-treatment individuals produced significantly more PCA compared with both baseline and control samples. All of the parameters were decreased or normal 1 week after stopping treatment. These data show that rHuG-CSF induces PMN activation and transiently affects some hemostatic variables in healthy HPC donor subjects. The clinical significance of these findings remains to be established.

Genetic modulation of coagulation factor VII plasma levels: contribution of different polymorphisms and gender-related effects

We studied the relationships among different polymorphisms of FVII gene in determining FVII levels, in a sample of 335 male and female Italian volunteers. The hypervariable region 4 (HVR4), the promoter decanucleotide insertion (-323 0/10 bp) and the R353Q polymorphisms of FVII gene were evaluated. The association of HVR4 or -323 0/10 bp polymorphism with plasma FVII levels differed between gender (Interaction term: p = 0.02 and p = 0.03, respectively), showing stronger effect in males than in females. In males, the R353Q and the HVR4 polymorphisms showed an incremental influence on FVII variance (F = 8.9, p <0.001 and F = 4.4, p = 0.01, respectively). Moreover, the effects of Q and 10 bp alleles on the reduction of FVII activity levels were significantly potentiated by the presence of H7 allele of HVR4 (Interaction term p = 0.03 for R353Q*HVR4 and p = 0.03 for -323 0/10 bp*HVR4). In conclusion, the effect of FVII polymorphisms on FVII levels was gender dependent and derived from a complex interaction among them. The HVR4 polymorphism seems to add an independent, albeit small, contribution to the regulation of FVII plasma levels.

Cancer procoagulant and tissue factor are differently modulated by all-trans-retinoic acid in acute promyelocytic leukemia cells

All-trans-retinoic acid (ATRA) downregulates the expression of two cellular procoagulants, tissue factor (TF) and cancer procoagulant (CP), in human promyelocytic leukemia cells. To evaluate whether or not changes of the procoagulant activities (PCAs) may share mechanisms with the ATRA-induced cyto-differentiation process, we have characterized the effect of ATRA on the TF and CP expression by NB4 cells, an ATRA maturation-inducible cell line, and two NB4-derived cell lines resistant to ATRA-induced maturation, the NB4. 306 and NB4.007/6 cells. Next, we evaluated the effect on the PCAs of the NB4 parental cells of three synthetic retinoid analogues, ie: AM580 (selective for the retinoic acid receptor [RAR] alpha), capable to induce the granulocytic differentiation of NB4 cells; and CD2019 (selective for RARbeta) and CD437 (selective for RARgamma), both lacking this capability. Cells were treated with either ATRA or the analogues (10(-6) to 10(-8) mol/L) for 96 hours. The effect on cell differentiation was evaluated by morphologic changes, cell proliferation, nitro blue tetrazolium reduction assay, and flow cytometry analysis of the CD33 and CD11b surface-antigen expression. PCA was first measured in 20 mmol/L Veronal Buffer cell extracts by the one-stage clotting assay of normal and FVII-deficient plasmas. Further TF and CP have been characterized and quantified in cell-sample preparations by chromogenic and immunological assays. In the first series of experiments, ATRA downregulates both TF and CP in NB4 parental cells, as expected. However, in the differentiation-resistant cell lines, it induced a significant loss of TF but had little or no effect on CP. In a second series of experiments, in the NB4 parental cells, the RARalpha agonist (AM580) induced cell maturation and reduced 91% CP expression, whereas CD437 and CD2019 had no cyto-differentiating effects and did not affect CP levels. On the other hand, in the same cells the TF expression was reduced by ATRA and AM580, but also by the RARbeta agonist CD2019, which did not induce cell maturation. These data indicate that in NB4 cells, ATRA modulation of CP occurs in parallel with signs of cell differentiation, while the regulation of TF appears to be at least in part independent from these processes, and involves both alpha and beta nuclear retinoid receptors.

Aspirin increases the bleeding side effects in essential thrombocythemia independent of the cyclooxygenase pathway: role of the lipoxygenase pathway

Acetylsalicylic acid (ASA) is currently recommended as an antithrombotic for patients with essential thrombocythemia (ET) who are at an increased risk of thrombotic events. However, ASA is also associated with an increased risk of bleeding in these patients as compared to the risk of bleeding in other patients treated with ASA. Recent data suggest that while ASA inhibits platelet thromboxane A2 (TxA2) synthesis in all individuals, ASA has little effect or inhibits the lipoxygenase pathway (i.e., 12-hydroxyeicosatetranoic acid or 12-HETE synthesis) in some individuals, and enhances 12-HETE synthesis in others. These differential effects are associated with a pronounced prolongation of the bleeding time vs. no prolongation of the bleeding time, respectively, i.e., in ASA responders and ASA nonresponders, respectively. To determine if the increased risk of ASA-induced bleeding seen in ET patients is associated with an effect on 12-HETE synthesis, we compared the relative effects of ASA on the bleeding time, platelet TxA2 and 12-HETE synthesis, and platelet aggregation and adhesion in ET patients and healthy volunteers. ASA (300 mg, taken orally) prolonged the bleeding time in 82% of the ET patients but only 27% of the healthy volunteers although platelet TxA2 synthesis and ADP- and collagen-induced aggregation were inhibited significantly in both groups. In contrast, platelet 12-HETE synthesis was unchanged and platelet adhesion was decreased in those patients and volunteers whose bleeding times were prolonged by ASA, whereas platelet 12-HETE synthesis was increased significantly and platelet adhesion was unaffected in those patients and volunteers whose bleeding times were not prolonged, and in some cases shortened by ASA. These results confirm previous data that demonstrate that ASA has different effects on platelet 12-HETE synthesis and platelet adhesion in different individuals, i.e., inhibitory or no effect in ASA responders (in whom ASA prolonged bleeding) vs. enhancing effects in ASA nonresponders (in whom ASA did not prolong bleeding). These results also indicate that there is a greater percentage of ASA responders in patients with ET than that seen in the general population, a difference that is associated with an effect of ASA on the lipoxygenase pathway. This may explain the increased bleeding side effects seen in the ET patient population.

The effect of very-low-dose warfarin on markers of hypercoagulation in metastatic breast cancer: results from a randomized trial

Malignancy is a risk factor for thromboembolism and anti-cancer chemotherapy can increase this risk. Prophylaxis of thrombosis with very-low-dose warfarin given concurrently with chemotherapy has a significantly reduced rate of thromboembolism in a randomized trial in women with stage IV breast cancer. In a group of 32 patients randomized in one center (16 subjects on warfarin and 16 on placebo), we have prospectively studied the plasma levels of: 1. Markers of 'in vivo' clotting activation (thrombin-antithrombin complex [TAT], prothrombin fragment 1+2 [F1+2] and D-dimer), 2. Factor VII (FVII), and 3. Natural anticoagulants (protein C [PC] and antithrombin [AT]). The aims of this study were: 1. to examine whether laboratory tests predicted those patients who developed thrombosis, and 2. to evaluate the effect of very-low-dose warfarin on hemostatic variables. The patients' hemostatic parameters were evaluated before entry into the study and after starting chemotherapy +/- prophylaxis, before each course for nine courses. Before-treatment results were compared to those of a sex and age-matched non-cancer control group. There was a significant elevation of plasma levels of TAT (p <0.001), F1+2 (p <0.001), D-dimer (p <0.0001) and FVIIa (p <0.05), as well as an increase of FVII proteolysis (p <0.05), whereas plasma PC and AT concentrations were not different from controls. After starting chemotherapy, markers of clotting activation were progressively lower in the group receiving warfarin prophylaxis compared to the group on placebo. Differences between the groups became statistically significant (p <0.01) after the 4th course of chemotherapy. Deep vein thrombosis occurred in two patients in the placebo arm. The results of this study indicate that before therapy, an hypercoagulable state is present in stage IV breast cancer, and after starting chemotherapy, abnormalities of hypercoagulation markers persist, however they are reduced by very-low-dose-warfarin. None of the laboratory variables could predict thrombosis in the single patient.

Effect of all trans-retinoic acid (ATRA) on the adhesive and motility properties of acute promyelocytic leukemia cells

All trans-retinoic acid (ATRA) induces complete remission in acute-promyelocytic-leukemia (APL) patients. This study investigated the adhesive properties of APL cells for the endothelium and the extracellular matrix, their motility and the effect of ATRA on these functions. Blasts from 7 APL patients adhered to resting and IL-1-activated endothelium, to the same degree as normal PMN. Adhesion was partially mediated by ICAM-1 and, for IL-1-activated endothelium, by VCAM-1 and E-selectin. These cells showed less adhesiveness for the matrix than PMN, although they maintained the same substrate preference: they adhered to fibronectin and thrombospondin, but not to laminin and type-IV collagen. Exposure to ATRA in vitro (1 microM for 48 to 96 hr) increased the adhesiveness of APL cells; this effect was particularly evident in the case of sub-endothelial matrix and fibronectin. A similar increment in adhesiveness was observed when comparing cells from 2 patients before and after treatment with ATRA. APL cells migrated in response to fMLP and motility was increased by ATRA. In conclusion, APL cells were less adhesive to the matrix than PMN, but treatment with ATRA considerably enhanced their adhesive properties. This could be important in determining the efflux of leukemic cells from the bone marrow and their tissue infiltration during ATRA therapy.

All-trans-retinoic acid increases adhesion to endothelium of the human promyelocytic leukaemia cell line NB4

Pulmonary distress symptoms and thrombotic complications are side-effects of all-trans-retinoic acid (ATRA) therapy for remission induction in acute promyelocytic leukaemia (APL). The ATRA-induced increase of leukaemic cell adhesive molecules may be responsible. To explore this we used a functional assay to study the effect of ATRA treatment on the adhesion of blast cells to cultured human endothelial cells (EC), endothelial cell matrix (ECM), and interleukin 1beta-activated EC (IL1 + EC). NB4 cells, a maturation-inducible human promyelocytic leukaemia cell line, were treated with 1 microM ATRA or the vehicle (control), labelled with 51Cr and tested in the adhesion assay. ATRA increased NB4 adhesion to EC (P<0.01), ECM (P<0.001) and IL1 + EC (P=n.s.). An inhibition study with anti-EC adhesion receptors MoAbs indicated that anti-E-selectin, anti-VCAM-1 and anti-ICAM-1 effectively inhibited cell adhesion to IL1 + EC (18+/-7%, 45 +/-6.9% and 29+/-6% inhibition, respectively) and to unstimulated EC. Preincubation of ATRA-treated NB4 cells with MoAbs anti-VLA4 and anti-LFA1, the VCAM-1 and ICAM-1 counter-receptors respectively, resulted in a significant inhibition of adhesion. Cytofluorimetric analysis of the NB4 cell membrane molecules confirmed the increase under ATRA of VLA4, LFA1, MAC1 and ICAM-1. Therefore ATRA increases NB4 cell adhesion to the endothelium and the subendothelial matrix. These findings parallel the increment of NB4 surface adhesive molecules, among which VLA4 and LFA1 appear to play an important part. These mechanisms may contribute to the complications of ATRA therapy in APL.

Proteolysis of von Willebrand factor is decreased in acute promyelocytic leukaemia by treatment with all-trans-retinoic acid

Plasma von Willebrand factor (VWF) was investigated in five patients with acute promyelocytic leukaemia (APL) before and after administration of the differentiating agent all-trans-retinoic acid (ATRA). The purpose of this study was to see how the proteolytic state associated with APL affects VWF structure and function and whether ATRA reverses any abnormality. At the onset of APL, multimeric analysis of plasma VWF revealed a lack of the largest multimers. After ATRA, there was a progressive correction of the multimeric pattern in all cases, with transient appearance of ultralarge multimers in two cases. Proteolysis was investigated with immunopurified and reduced VWF from each patient's plasma. This was electrophoresed and probed with two monoclonal antibodies that identify the 225 kD native subunit and the three native fragments of 189, 176 and 140 kD and differentiate novel proteolytic fragments produced by different proteinases. At the onset of APL, the 225 kD native subunit was relatively decreased, with the appearance of an array of novel VWF proteolytic fragments, ranging in size from <140 to <225 kD. These novel fragments observed in patients were similar to those produced in vitro by digestion of purified VWF with plasmin or elastase. After ATRA therapy, proteolysis diminished progressively in parallel with the improvement of other haemostatic measurements, but persisted to some extent. We conclude that VWF proteolysis in APL is produced by plasmin and elastase. Changes of VWF structure and function might adversely affect haemostasis in APL. Therefore, improvement of VWF after ATRA administration might explain in part the effectiveness of this drug in reducing haemorrhagic complications.

All-trans-retinoic acid counteracts endothelial cell procoagulant activity induced by a human promyelocytic leukemia-derived cell line (NB4)

Therapy with all-trans-retinoic acid (ATRA) can rapidly improve the coagulopathy of acute promyelocytic leukemia (APL). This study was designed to evaluate whether the APL cell line NB4 induces the procoagulant activity (PCA) of human endothelial cells (ECs) in vitro, and whether this property is modified after ATRA-induced NB4 maturation. EC monolayers were incubated for 4 hours at 37 degrees C with the conditioned media (CM) of NB4 treated with 1 mumol/L ATRA (ATRA-NB4-CM) or the vehicle (control-NB4-CM). EC lysates were tested for PCA. ATRA-NB4-CM induced significantly more PCA:tissue factor (TF) than control-NB4-CM (P < .01). To identify the cause of TF induction, interleukin (IL)-1 beta antigen levels were measured in CM samples. ATRA-NB4-CM contained significantly more IL-1 beta than control-NB4-CM. EC PCA was significantly inhibited by an anti-IL-1 beta antibody. The addition to the media of 10 mumol/L ATRA counteracted the EC TF expression induced by NB4-CM. These data indicate that ATRA increases the promyelocyte-induced EC TF, partly through increased IL-1 beta production. However, ATRA can protect the endothelium from the procoagulant stimulus of leukemic cells.

Loss of blast cell procoagulant activity and improvement of hemostatic variables in patients with acute promyelocytic leukemia administered all-trans-retinoic acid

All-trans-retinoic acid (ATRA) induces complete remission (CR) in up to 90% of acute promyelocytic leukemia (APL) patients with rapid amelioration of the bleeding syndrome. Previous studies indicate that ATRA treatment in vitro of the APL NB4 cell line can affect their procoagulant activity (PCA). To assess whether ATRA has this effect also in vivo, we prospectively studied the PCA of bone marrow blasts from APL patients on therapy with ATRA alone or associated with chemotherapy. Samples were obtained before, during, and after ATRA. To characterize the coagulopathy, we measured a series of plasma hemostatic variables before and during the first two weeks of therapy, as follows: (1) markers of hypercoagulability; (2) natural anticoagulants; (3) fibrinolysis proteins; and (4) elastase. The results by enzymatic and immunologic methods show that both total (tissue factor-like) and factor VII-independent (cancer procoagulant-like) blast cell PCAs, present before therapy, were reduced during (69% and 65% decrement, respectively) and virtually undetectable after ATRA. The plasma hemostatic assessment of patients before treatment was elevated hypercoagulability markers, low mean protein C, normal fibrinolysis proteins, and increased elastase. After starting ATRA, hypercoagulability markers were reduced within 4 to 8 days, protein C augmented, the overall fibrinolytic balance was unmodified, and elastase remained elevated. These results were not different either with or without chemotherapy and are consistent with the clinical findings of rapid improvement of the coagulopathy.

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.

Recombinant versus high-sensitivity conventional thromboplastin: a randomized clinical study in patients on oral anticoagulation

A prospective, randomized, double-blind clinical trial was carried out in a single center to compare the clinical and laboratory quality of oral anticoagulant therapy monitored with recombinant tissue factor (RTF) or with a sensitive, human-derived, conventional thromboplastin (CT) in the PT test. Seven hundred and fifty-seven consecutive patients receiving oral anticoagulation for various indications were randomized to RTF (n = 379) or CT (n = 368) for 6 months. Total follow-up was 167 and 153 patient-years for RTF and TP groups respectively. Fifty-six bleeding events were observed: 31 in the RTF group and 25 in the TP group. The incidence of bleeding was 18.5 and 16.5% pt-yrs for RTF and TP patients respectively (n.s.). The event-free follow-up curves were not significantly different between the two groups. The laboratory quality of oral anticoagulation was evaluated with the "last check in file" method: therapeutic INR was found in the same proportion of RTF and TP patients (70.2% vs 68.8%). Our study shows that RTF is as effective as a sensitive, conventional thromboplastin for monitoring oral anticoagulation.

Hemostatic system activation in patients with lupus anticoagulant and essential thrombocythemia

Hemostatic system activation was estimated in the plasmas of 39 patients with LAC and 19 patients with ET by measuring concentrations of TAT complex and prothrombin F1+2. The concentrations of FVII, recognized previously as a risk factor for arterial thrombosis, were also measured. None of the patients had active thrombosis during this study. The mean TAT and F1+2 levels in LAC and ET plasmas were higher than the respective values in the plasmas of healthy control subjects. Compared with their respective controls, TAT levels were significantly higher in the LAC group (P < 0.05) and F1+2 was significantly higher in the ET group (P < 0.005). The mean FVIIt and FVIIz was significantly higher (P < 0.05 and P < 0.01, respectively) in LAC than control plasmas. Furthermore, the differences between FVIIt and FVIIz were significantly greater in LAC than control plasmas, indicating increased in vivo proteolysis of FVII in LAC. Although the mean concentrations of these two FVII parameters in ET plasma were not significantly different from those of normal plasmas, the FVII levels were higher in 30% of ET plasmas than the upper limit of controls. Our results are consistent with hypercoagulation in LAC and ET patients, and this may be a contributory factor for the increased rates of thrombosis associated with the two conditions.

Further characterization of platelet-aggregating cysteine proteinase activity in thrombotic thrombocytopenic purpura

Circulating platelet-aggregating activities have been described by several authors. In a previous study we have confirmed the presence in serum and plasma from patients with thrombotic thrombocytopenic purpura (TTP) of a platelet aggregating cysteine proteinase (PACP). This activity differed in that, among the class of thiol enzymes, it showed characteristics of a lysosomal cathepsin rather than of a cytoplasmic calpain. To further investigate the enzymatic properties of this PACP we have designed a study to evaluate the dependence of the activity on Ca++. Calcium-dependence is a property of calpains but not of cathepsins. A proteolytic assay was set up and conducted with and without Ca++. The release of acid-soluble peptide from denatured human globin promoted by TTP samples and standards was fluorimetrically measured. The results show that TTP samples were equally active with and without Ca++ similar to standard papain (the cathepsin B-like proteinase), whereas standard calpain only acted with Ca++. An inhibition study performed by the proteolytic assay confirmed the same pattern of sensitivity of PACP to a series of specific cystein proteinase inhibitors previously shown by the proaggregating assay. The enzymatic behaviour of PACP of TTP resembled a lysosomal (cathepsins) rather than a cytoplasmic (calpains) cysteine proteinase.

Double-blind randomised trial of a very-low-dose warfarin for prevention of thromboembolism in stage IV breast cancer

Patients receiving chemotherapy for metastatic breast cancer are at high risk of thromboembolic disease. Long-term oral anticoagulant therapy is needed but increases the risk of haemorrhagic complications. We have assessed the safety and efficacy of warfarin in very low doses as prophylaxis. Women receiving chemotherapy for metastatic breast cancer were randomly assigned either very-low-dose warfarin (152 patients) or placebo (159). The warfarin dose was 1 mg daily for 6 weeks and was then adjusted to maintain the prothrombin time at an international normalised ratio (INR) of 1.3 to 1.9. Study treatment continued until 1 week after the end of chemotherapy. The average daily dose from initiation of titration was 2.6 (SD 1.2) mg for the warfarin group and the mean INR was 1.52. The mean time at risk of thrombosis was 199 (126) days for warfarin-treated patients and 188 (137) days for placebo recipients (p = 0.45). There were 7 thromboembolic events (6 deep-vein thrombosis, 1 pulmonary embolism) in the placebo group and 1 (pulmonary embolism) in the warfarin group, a relative risk reduction of about 85% (p = 0.031). Major bleeding occurred in 2 placebo recipients and 1 warfarin-treated patient. There was no detectable difference in survival between the treatment groups. Very-low-dose warfarin is a safe and effective method for prevention of thromboembolism in patients with metastatic breast cancer who are receiving chemotherapy.