Association of phosphatidylinositol 3-kinase, via the SH2 domains of p85, with focal adhesion kinase in polyoma middle t-transformed fibroblasts.

Focal adhesion kinase (FAK), a non-receptor protein tyrosine kinase, becomes activated and phosphorylated on tyrosine in cells transformed with v-src. By cytoimmunofluorescence a sub-fraction of the p85 subunit of phosphoinositide 3-kinase (PI 3-kinase) localized in focal adhesion plaques. We examined the possibility that FAK associates with PI 3-kinase. In fibroblasts transformed with polyoma middle t, PI 3-kinase activity co-immunoprecipitated with pp125FAK using two different antibodies against this protein. PP125FAK from middle t-transformed cells associated with a glutathione-S-transferase fusion protein containing the 85-kDa subunit of phosphatidylinositol 3-kinase. Both of the SH2 domains and the SH3 domain of p85 also formed complexes with pp125FAK in vitro. Phosphopeptides that bind to the SH2 domains completely blocked the binding of full-length p85 to pp125FAK, while a peptide that binds to the SH3 domain was ineffective, indicating that the association between p85 and pp125FAK is mediated by the SH2 domains of p85.

Ifosfamide is an active drug in Wilms' tumor: a phase II study conducted by the French Society of Pediatric Oncology.

Twenty-one patients with advanced Wilms' tumor entered a phase II study with high-dose ifosfamide (3 g/m2 over two days every 15 days). Mesna and hyperhydration were associated with minimal bladder toxicity. After two courses, five partial responses and six complete responses were observed. Ten patients did not respond. The median duration of response was 2 months (range, 1 to 7). Therapy was delayed because of leukopenia for 1 or 2 weeks in only three cases. Fever and infection were not observed. Seven patients presented with hematuria, three of whom were among the 17 patients coadministered mesna, which did not interfere with subsequent therapy.

Mechanisms involved in platelet activation induced by a monoclonal antibody anti glycoprotein IIb-IIIa: inositol phosphate production is not the primary event.

The mechanisms involved in platelet aggregation by a monoclonal antibody (mAb) P256 specific for the GPIIb-IIIa complex was investigated following metabolic 32P labelling of platelets. When compared with thrombin, inositol phosphates (InsP) production during P256-induced activation was delayed and no apparent peak, but a small and sustained production of [32P]-Ins(1,4,5)P3 and [32P]-Ins(1,3,4,5)P4, was observed between 20 and 90 s. [32P]-Ins(1,3,4)P3 was also produced with a maximum after 90 s. Addition of the ADP scavenger creatinine phosphate/creatine phosphokinase (CP/CPK) and of the cyclooxygenase inhibitor aspirin together with P256 almost totally abolished InsP formation, whereas platelet aggregation and protein phosphorylation were partially inhibited. F(ab')2 fragments of P256 also aggregated platelets but to a smaller extent than IgG, and without any measurable InsPs. To characterize further P256-induced activation, the phosphorylation of p43, the main substrate of protein kinase C (PKC) and the phosphorylation of tyrosine protein (P-Tyr) was also studied. PKC activation was smaller with P256-IgG than with thrombin but both thrombin and P265-IgG induced a similar profile of P-Tyr involving seven major bands, whereas P256-F(ab')2 only occasionally activated PKC but always significantly phosphorylated a 64,000 molecular weight P-Tyr. The data indicate that the binding of P256 to GPIIb-IIIa, in contrast with thrombin, does not initially lead directly to the activation of the phosphoinositide phospholipase C to produce InsP's but rather involves the activation of protein kinases and also both fragments F(ab')2 and Fc play a specific role in the platelet responses to the mAb. Only the crosstalk between the two pathways evoked by F(ab')2 and Fc respectively allows the activation of all platelet activation systems.

Association of the protein tyrosine phosphatase PTP1C with the protein tyrosine kinase c-Src in human platelets.

Protein tyrosine phosphatase 1C (PTP1C), highly expressed in hematopoietic cells, is a soluble protein tyrosine phosphatase containing two Src homology 2 (SH2) domains at the N-terminus and two putative sites of tyrosine phosphorylation at the C-terminus. This paper reports that PTP1C and c-Src could be coimmunoprecipitated during thrombin-induced platelet activation. Moreover, association between the two signalling proteins occurred only after PTP1C had been tyrosine phosphorylated. In in vitro experiments, PTP1C bound to the SH2 domain of c-Src, suggesting that association between tyrosine phosphorylated PTP1C and c-Src was mediated by the SH2 domain of c-Src. Finally, in resting platelets, PTP1C was mainly found in the Nonidet P-40 soluble fraction whereas following thrombin-induced activation, around 17% of PTP1C was associated with the insoluble fraction.

Role of Fc gamma RIIA gene polymorphism in human platelet activation by monoclonal antibodies.

The aim of this study was to determine if there is a correlation between the activity of a MoAb as an agonist and its ability to bind to the Fc platelet receptor, Fc gamma RIIa. A polymorphism at amino acid 131 [arginine (Arg) or histidine (His)] of Fc gamma RIIa was first shown to be determinant for MoAb-IgG1 binding on monocytes. To clarify the role of this polymorphism in platelet activation by MoAb-IgG1 we (i) established the Fc gamma RIIa polymorphism at the gene level by adapting the denaturating gradient gel electrophoresis method, (ii) analyzed the binding affinity of the MoAbs to Fc gamma RIIa on platelets from homozygous Arg, homozygous His, and heterozygous Arg/His donors, and (iii) characterized the different reactivities of platelets according to the Fc gamma RIIA polymorphism. Among 167 caucasian donors we found 46% heterozygous Arg/His, 36% homozygous His and 18% homozygous Arg. ALB6, and anti CD9, P256 an anti GPIIb-IIIa, and AP3 an anti-GPIIIa were chosen according to their ability (ALB6, P256) or not (AP3) to activate platelets. These 3 MoAbs-IgG1 bind to Fc gamma RIIa with a stronger affinity for the Arg-form of Fc gamma RIIa, a result which was confirmed with the use of diverse MoAbs directed against various antigens. The different abilities of MoAbs to bind to the two Fc gamma RIIa forms were well correlated to the different platelet responses induced by ALB6 and P256. However, low concentrations of ALB6, which allow full activation of platelets from homozygous Arg donors, as did P256, did not induce any activation of platelets from homozygous His donors, whereas P256 is able to induce a low aggregation. The results further define the respective roles of the antigen and the Fc receptor, depending on the MoAb, and the role of the Fc gamma RIIa polymorphism in platelet activation induced by MoAbs. In addition, the results obtained with MoAbs unable to induce platelet activation provided evidence that the binding of a MoAb on Fc gamma RIIa does not predict its ability to activate platelets.

Inhibition of platelet activation by tyrosine kinase inhibitors.

Protein tyrosine kinase (PTK) blockers (tyrphostins) inhibit in a dose-dependent fashion thrombin-induced aggregation and serotonin release with IC50 values in the 10-35 microM concentration range. The inhibition of thrombin-induced aggregation correlates with their potency in inhibiting phosphorylation of proteins on tyrosine residues. Using metabolically 32P-labelled human platelets, it was found that the tyrphostins have no effect on the decrease in [32P]phosphatidylinositol bisphosphate but prevent the replenishment of [32P]polyphosphoinositide. Tyrphostins decreased [32P]phosphatidic acid production induced by thrombin, although never by more than 50%, and only delayed the peak of diacylglycerol, suggesting that phospholipase C was still activated. Tyrphostins inhibited the thrombin-elicited early phosphorylation of p43 and p20, substrates for protein kinase C (PKC) and myosin light chain kinase, respectively, at short times of activation. This inhibition, however, was overcome after 1 min of stimulation with thrombin. Tyrphostin AG213 also inhibited platelet aggregation and tyrosine protein phosphorylation induced by phorbol myristate acetate (PMA), but did not inhibit pleckstrin phosphorylation. These results suggest that thrombin induces the phosphorylation of proteins on tyrosine residues which most probably results in the activation of phosphoinositide kinases. The ability of tyrphostins to inhibit phosphorylation of p43 and p20 when induced by thrombin but not when induced by PMA confirms that PTKs may be involved subsequent to PKC activation.

[The reproduction in France of Rosen's protocol for osteosarcomas]. / La reproduction en France du protocole de Rosen pour les ostéosarcomes.

The authors treated 188 patients with osteosarcoma by chemotherapy followed by surgery and additional chemotherapy (Rosen's T regimen). In 14% of cases, infectious, neurologic or cardiac complications were observed, which resulted in death in 2% of the patients. Forty-six per cent responded well to the primary chemotherapy, 76% of which are alive and disease-free, as opposed to merely 42% of the bad responders.

[Antiplatelet glycoprotein monoclonal antibodies: properties and practical value]. / Anticorps monoclonaux antiglycoprotéines plaquettaires: propriétés et intérêts pratiques.

The aim of this review is (i) to classify the different monoclonal antibodies against platelet glycoproteins according to their properties and (ii) to take stock of their many diagnostic and therapeutic uses. Most of these antibodies recognize antigens on resting platelets without inducing activation, sometimes however they inhibit platelet function. Some of these antibodies, especially those against specific antigens (GPIIb/IIIa, CD9, CD36), have the capacity to activate platelets in vitro, either by direct binding of antibodies on the antigen or through the Fc domain binding to its platelet receptor Fc gamma RII. Other antibodies are directed against activation-dependent antigens that are expressed as a result of (i) a modification of a glycoprotein structure during platelet activation (as for GPIIb/IIIa), (ii) platelet release of granular antigens (GMP140, CD63, granulophysin...) or (iii) binding of soluble antigens on the activated platelet surface. Monoclonal antibodies find practical applications for both in vitro and in vivo diagnosis of bleeding or thrombotic pathology with some of them, notably anti-GPIIb/IIIa, having a promising future for antithrombotic therapy.

[Heparin induced autoimmune thrombocytopenia: assessment of a rapid functional assay]. / La thrombopénie immunoallergique induite par l'héparine: evaluation d'un test fonctionnel rapide.

Heparin-induced thrombocytopenia (HIT) diagnosis is often difficult. Depending on the patients, the thrombocytopenia could be due to various causes. Despite their poor sensitivity and specificity, biological tests are necessary to clarify the diagnosis. In 1985, a new heparin-induced platelet aggregation assay was described that consists in determining the percentage of aggregated platelets by using an automated cell counter. Plasma samples from 18 patients with a definite HIT were tested with this quick easy-to-perform HIT diagnosis test. Positive results were obtained with 11 plasma (61%) when the test was performed with platelets from 3 different healthy volunteers (control platelets). As for the other functional tests, results are depending on control platelets and sensitivity seems to be increased when control platelets FcgammaRIIa-131 polymorphism was of His/His (but difference is not significant). In emergency situation, it is difficult to perform a functional test with control platelets from several healthy donors, and it is even more difficult to select volunteers on their FcgammaRIIa-131 polymorphism. In conclusion, in spite of its practicability, the test is not reliable to help in the rapid diagnosis of HIT. Indeed, 7 patients of 18 (39%) with definite HIT have been found negative with this test.

[Roles of iron overload and chelating treatment in Yersinia infectious complicated by major thalassemia]. / Rôles de la surcharge martiale et du traitement chélateur dans les infections à Yersinia survenant sur une thalassémie majeure.

A study of 3 personal and 32 published cases showed that Yersinia septicaemia in subjects under 21 presents as digestive disorders with fever and occurs in one half of the cases in thalassaemia patients. Among the factors which may be blamed for this predisposition the most important are excessive tissue iron levels and treatment with chelating agents. Iron overload is present in 70% of patients with Yersinia septicaemia. The risk of infection in such subjects requires appropriate therapeutic measures.

[Intravenous administration of deferoxamine in over-night hospitalization: efficacy and good psychological tolerance in thalassemic children]. / Administration intraveineuse de desférioxamine en hospitalisation de nuit: efficacité et bonne tolérance psychologique pour les enfants thalassémiques.

Daily subcutaneous infusion of deferoxamine in thalassemia and other transfusion dependent-patients can successfully treat iron overload, but most patients, mainly young children and teenagers may not comply with this method. Experience with nightly intravenous infusion of deferoxamine (8 g) through a subcutaneous-port over 5 out of 21 days, is reported in 4 children with dramatic improvement in clinical status, ferritin levels and quality of life.

[Role and therapeutic use of deferoxamine in iron overload due to thalassemia (author's transl)]. / La desferrioxamine B: rôle et modalités d'utilisation dans le traitement de la surcharge martiale de la thalassémie majeure.

Eight children aged between 4 and 16 years with thalassemia major were treated for 30 months with repeated transfusions and a chelating agent. Deferoxamine was given intravenously for 12 months and subcutaneously in the next 18 months. The results of urine iron concentrations, the practical difficulties of both routes of administration and the clinical results are presented. The therapeutic regime proposed is capable or reducing the iron overload.

[Microangiopathic anemia following thrombopenic purpura]. / Anémie microangiopathique succédant à un purpura thrombopénique idiopathique.

BACKGROUND: Chronic relapsing microangiopathic hemolytic anemia is rare in children. This report describes a case associated with thrombocytopenia following idiopathic thrombocytopenic purpura. CASE REPORT: A 4 year-old girl was admitted for acute idiopathic thrombocytopenic purpura (platelet count: 12,000/mm3) without anemia or fragmented red cells. The patient was given intravenous gammaglobulins without success, followed by prednisone (2 mg/kg/day). The platelet count was normalized, but decreased when the treatment was discontinued. The patient developed acute intracranial hypertension at the age of 5 yr 8 mo, following two cerebral hematomas. The platelet count was 9,000/mm3. A second course of intravenous gammaglobulins and prednisone was unsuccessful, so a splenectomy was performed. One year later, the patient was admitted because of diffuse purpura, anemia and jaundice. Hematologic findings were: Hb 8.4 g/dl, reticulocytes 448,200/mm3, fragmented red cells 16%, platelets 15,000/mm3, WBC 22,400/mm3. Seroimmunologic investigation showed a high titer of antinuclear antibodies. Examination for viral etiology was negative. Intravenous gammaglobulins had a transient effect on platelets, reticulocytes and fragmented red cells. The patient was then given vincristine plus prednisone; they were only effective when high doses were used. A second intracerebral hemorrhage occurred when the patient was given low doses of drugs. After 3 other hematologic relapses, the vincristine was stopped without further complication. CONCLUSION: The criteria for systemic lupus erythematous were not satisfied, despite the presence of antinuclear antibodies. A congenital deficiency of an unidentified plasma factor that reverses microangiopathic hemolysis and thrombocytopenia was not demonstrated in this patient, who could not be given fresh frozen plasma.

[An evaluation of cerebrospinal fluid cytology in childhood leukaemias and lymphomas (author's transl)]. / Cytologie du liquide céphalo-rachidien dans les leucémies aiguës et lymphomes non hodgkiniens de l'enfant.

A cytological study of the cerebrospinal fluid was carried out on 72 children with leukaemia or lymphoma either at the onset or during the course of the disease. It proved extremely useful in revealing the presence of malignant cells in CSF's with normal cell count and in distinguishing with absolute certainty meningeal leukaemias from meningeal reactions of other origins, in particular the frequent histiocytic reactions to radiotherapy and/or chemotherapy. These "irritative" reactions are a reminder that iatrogenic damage to the central nervous system is a distinct possibility, and the modalities of treatment should perhaps be reconsidered when they attain a certain magnitude.

[Massive breast involvement in Burkitt's lymphoma]. / Infiltration mammaire massive au cours d'un lymphome de Burkitt.

Massive bilateral breast involvement in the course of a Burkitt's lymphoma is reported as an exceptional occurrence in a 13 year-old girl, in early puberty. It was an extensive form, stage IV, with massive organ involvement but without CNS involvement. Chemotherapy (LMB 84) induced total cure (18 months disease free survival).

[Pulmonary and cerebral aspergillosis in Burkitt's lymphoma]. / Aspergillose pulmonaire et cérébrale au cours d'un lymphome de Burkitt.

Multiple intracerebral aspergillus abscesses in a 5 year old boy with a Burkitt's lymphoma are described. The disease was fatal despite antifungal treatment. The diagnostic and therapeutic problems, the risk factors and preventive care are discussed.

Indapamide inhibits human platelet aggregation in vitro: comparison with hydrochlorothiazide.

Among antihypertensive drugs with diuretic properties, indapamide was shown to inhibit platelet growth factors production in diabetic hypertensive patients, suggesting an antiplatelet activity. The present study aimed to demonstrate the antiaggregating properties of indapamide. The effect of indapamide on platelet function was compared in vitro to that of hydrochlorothiazide. Indapamide (100 microM) inhibited the second wave of adenosine diphosphate-induced aggregation and inhibited collagen-induced aggregation of platelet rich plasma by 50%. Using isolated platelets, indapamide also inhibited aggregation induced by low doses of thrombin (70% inhibition with 0.035 U/ml). This inhibition was dose-dependent and was still observed in presence of high thrombin concentrations, although the inhibition was moderate. Inhibitory effect of indapamide was more pronounced on the release reaction. Indapamide inhibited the thrombin-induced release of serotonin from dense granules by up to 80%. Hydrochlorothiazide at the same concentrations had no effect on platelet aggregation, and the inhibitory effect on the secretion was inconsistent and never exceeded 30%. By contrast, when the aggregation inducer was arachidonic acid, indapamide had no effect either on aggregation or on thromboxane formation, indicating that it was not acting on arachidonic catabolism. Calcium mobilization evoked by thrombin stimulation and measured with the fluorescent dye Indo 1 was also reduced in presence of indapamide by 30%. Myosin light chain and pleckstrin phosphorylation induced by thrombin were also reduced. These results demonstrate that indapamide inhibits platelet responses by inhibiting calcium mobilization. The anti-aggregating properties of indapamide could contribute to normalize the hyperresponsiveness of platelets from hypertensive patients.

[Primary germinal tumors of the central nervous system]. / Tumeurs germinales primitives du système nerveux central.

Primary intra-cranial germ-cell tumors are a rare and heterogeneous group of neoplasms, identical to germ-cell tumors of gonads and other organs. These tumors arise along the midline, from the supra-sellar cistern to the pineal gland, and have neurological, ophthalmological, and endocrinological expression. The diagnosis is established by detection of increased levels of tumoral markers and/or by histological examination. The treatment includes chemotherapy, radiotherapy and surgery.

[Brain stem tumors in children]. / Tumeurs du tronc cérébral de l'enfant.

Gliomas involving the brain stem represent 10% of pediatric central nervous system neoplasms. They result in multiple cranial nerve involvement, long tracts signs, cerebellar signs, usually with no evidence of raising in intracranial pressure. The diagnosis is established by computed tomographic scan and magnetic resonance imaging. Classic management consists in conventional radiation therapy but the prognosis is very dismal with a five year survival rate about 30%.