Rák K

Alterations of P53 and RB genes and the evolution of the accelerated phase of chronic myeloid leukemia.

Using the single-strand conformation polymorphism and heteroduplex analyses, the P53 and RB genes were analyzed in cell samples from twenty-eight patients with chronic myeloid leukemia (CML) both at diagnosis and at the onset of accelerated phase (AP) of the disease. No alterations of the P53 or RB genes were found in any of the chronic phase (CP) samples. Structural abnormalities of the P53 gene were observed in ten of twenty-eight AP samples within exons 4, 5, 7 and 9. Of the ten cases of AP disease with altered P53 genes, five patients also suffered from the deletion of the other allele. Alterations of the RB gene could be detected in six AP samples, and aberrant band patterns were found in the analysis of exons 2, 3, 4, 6, 7, 13, 14, 17, 21 and 26. Among the six AP samples with structural abnormalities of the RB gene, two showed the loss of the other allele. It is of note that alterations of both P53 and RB genes were observed in two AP samples. Our data strongly suggest that abnormalities of the P53 and RB genes and acceleration of CML are linked events in some cases of AP.

Reduced In Vitro Clot Lysis and Release of More Active Platelet PAI-1 in Polycythemia Vera and Essential Thrombocythemia

Because platelets interact with fibrinolysis in a complex manner, it can be expected that with abnormal platelet numbers and quality this interference can be even more profound. The aim of this work was to study the lysis-resistance of platelet-rich clots in diseases with high platelet counts: polycythemia vera (PV), essential thrombocythemia (ET) and to make comparison with polyglobulia (PG). Platelet-rich plasma (PRP) and platelet-poor plasma (PPP) were analyzed by an in vitro clot lysis test. Plasminogen activator inhibitor-1 (PAI-1) activity was measured in plasma and in the supernatants of the washed and gel-filtered platelets after activation by thrombin. The lysis showed decreased speed of PPP-clots in PV and ET. This phenomenon was even more marked in PRP-clots from PV and ET, but further increased lysis resistance after retraction was not observed in PV and ET, most likely due to abnormal platelet functions. Our results suggest that the fibrinolytic activity is reduced in PV and ET, and may play a role both in the increased aptitude for venous thrombosis and in the arterial complications. These are partly caused by higher plasmatic PAI-1 activity as well as by more active platelet PAI-1. The PAI-1 activity was significantly higher in the supernatants of the washed and gel-filtered platelets of PV after activation by thrombin compared with controls. Other factors might have influenced the reduced fibrinolysis.

Frequent methylation of p16INK4A and p14ARF genes implicated in the evolution of chronic myeloid leukaemia from its chronic to accelerated phase.

The frequency and mechanism of p16(INK4A) and p14(ARF) gene alterations were studied in cell samples from 30 patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukaemia (CML), both at diagnosis and at the onset of the accelerated phase (AP) of the disease. No alterations in the p16(INK4A) or p14(ARF) genes were found in any of the chronic phase (CP) samples. DNA sequencing analyses detected p16(INK4A) or p14(ARF) mutations in 17 AP samples. All mutations were heterozygous without loss of the other allele. Aberrant methylation of the p16(INK4A) or p14(ARF) promoters was found in 14 of 30 AP samples. The most common situation was the simultaneous methylation of both promoters. Our data indicate that p16(INK4A) and p14(ARF) are primary targets for inactivation by promoter methylation in the acceleration of CML. Transcriptional silencing of the p16(INK4A) and p14(ARF) genes may be important in the conversion of CML from the CP to the AP.

Platelet insulin receptor determination in non-insulin dependent diabetes mellitus

The platelet membrane insulin receptors of healthy and non-insulin dependent (type 2) diabetic patients were studied. Receptor number and affinity proved to be decreased in type 2 diabetes mellitus. The changes in platelet insulin receptor characteristics are in good correlation with the alterations reported in other tissues or cells. The possible role of these phenomena in the pathogenesis of disturbed platelet function in diabetics needs further investigation.

Plasma levels of beta-thromboglobulin and factor viii-related antigen in diabetic children and adults

In order to investigate the relationship between the in vivo platelet activation in diabetes mellitus and the endothelial damage connected with the diabetic micro- and/or macroangiopathy, plasma levels of beta-thromboglobulin (B-TG) and of factor VIII-related antigen (VIII R:Ag) were studied (1) in juvenile-onset (Type I) diabetics without clinical signs of angiopathy (age under 12 years) and (2) in mostly maturity-onset (Type II) diabetics with and without overt angiopathy (age between 14 and 60 years). Normal controls and nondiabetics with atherosclerosis were also studied. Plasma levels of both proteins were found to be elevated in all the groups of diabetic and atherosclerotic patients in comparison with the controls. Highest levels were found in adult diabetics with angiopathy and in atherosclerotics even without diabetes, but values of the diabetic children were also elevated. The data suggest a causal relationship between the vascular damage and the enhanced platelet reactivity in which the former may play the primary role.

Changes in Oncogene Expression Implicated in Evolution of Chronic Granulocytic Leukemia from its Chronic Phase to Acceleration

Expression of nine oncogenes was investigated in cell samples from fifteen patients with Philadelphia chromosome (Ph)-positive chronic granulocytic leukemia (CGL) both at diagnosis and at the onset of accelerated phase (AP) of the disease. The bcr-abl fusion gene, the H-ras gene and the c-myb gene were universally expressed. In comparison with the chronic phase (CP) of the disease, an increase in the levels of bcr-abl-, c-myb- and H-ras-related transcripts was found in three, two and three AP samples, respectively. Elevation of the bcr-abl-related message was associated with duplication of the Ph chromosome and amplification of the bcr-abl fusion gene in one AP sample. No CP samples were positive for c-myc or c-sis expression. On the contrary, c-myc and c-sis were expressed in three and four AP samples, respectively. The presence of c-myc-related transcript was associated with trisomy 8 with or without amplification of the c-myc oncogene in leukemia cells of two patients with CGL in AP. No changes of oncogene expression were found in four AP samples. However, we observed deletions of chromosome 13 and 17 or i(17q) in three of them, suggesting that tumor suppressor gene alterations may also be responsible for the development of AP of CGL. Our data indicate that heterogeneous alterations in oncogenes and tumor suppressor genes accompany the evolution of CGL-CP to the AP of the disease.

Plasma thromboxane and prostacyclin metabolite ratio in atherosclerosis and diabetes mellitus

Thromboxane and prostacyclin metabolite determinations (radioimmunoassay) were performed in obliterative atherosclerosis and in diabetes mellitus with microangiopathy. The shift of these metabolites to the thromboxane side could have been documented in both diseases. This phenomenon calls attention to an increased platelet activation and endothelial cell damage. In a third group patients received aspirin (500 mg on alternative days) which caused a marked inhibition of both thromboxane and prostacyclin production, measured this way. The possible role of altered balance of these two prostanoids in atherogenesis and diabetic angiopathy is discussed.

Endothelium Releases More von Willebrand Factor and Tissue-Type Plasminogen Activator upon Venous Occlusion in Patients with Liver Cirrhosis than in Normals

Venous occlusion was used in 8 patients with liver cirrhosis and in 10 normals to investigate the pathomechanism of long-term elevation of plasma von Willebrand factor antigen (vWFAg) in liver cirrhosis. The following parameters were determined at baseline, and immediately, 60 min and 24 h after 10 min venous occlusion: vWFAg, ristocetin cofactor (RiCoF), in vitro platelet retention (Adeplat T), and tissue-type plasminogen activator (t-PA). Every baseline value in the liver cirrhosis group was significantly higher than in the controls. In both groups the 10-min values were significantly higher than their corresponding baseline results. Hence, comparing the two groups, in liver cirrhosis a significantly higher release of vWFAg and t-PA could be observed. These findings suggest on the one hand that the increased release contributes substantially to the sustained elevation of plasma vWF level in liver cirrhosis. On the other hand, the results indicate that not only the vascular surface of the diseased liver but most probably the total endothelium plays an important role in this phenomenon.

Treatment of the severe bleeding episode in type III von Willebrand's disease by simultaneous administration of cryoprecipitate and platelet concentrate.

A severe, life-threatening bleeding episode in a 24-year-old woman suffering from type III von Willebrands disease was treated by large doses of cryoprecipitate with unsatisfactory results. Bleeding ceased and the bleeding time normalized only after concomitant administration of platelet concentrates. In the treatment of von Willebrands disease patients possessing platelets with absent or insufficient von Willebrand factor activity the administration of plasma concentrates together with platelets appears to be justified.

Demonstration of HTLV-Related Pro viral DNA Sequences and Antibodies Reactive with HTLV Internal Proteins in an Hungarian Patient with Sézary Syndrome

DNA sequences distantly related to the proviral DNA of HTLV-I were found in the leukemic cells of a Hungarian patient suffering from Sézary syndrome. Serum samples from the patient contained antibodies reactive with the internal core polypeptides of HTLV-I and HTLV-II, but not with the env gene encoded type-specific HTLV antigens. The husband and daughter of the patient also had antibodies of the same specificity. These findings suggest the presence of a virus distantly related to HTLV-I and HTLV-II.