Model for the growth of electrodeposited ferromagnetic aggregates under an in-plane magnetic field.

The quasi-two-dimensional deposition of ferromagnetic materials by electrochemical process under the influence of a magnetic field applied in the plane of the growth leads to a surprising symmetry breaking in the dendritic structures found. The reasons for these features are still not completely understood. The original dense circular envelope becomes rectangular, as well as the sparse figures have their shapes elongated. This paper reports the results of a diffusion-limited aggregation (DLA) -like simulation. The model proposed here, a modification of the original DLA model, can deal with ferromagnetic particles under the influence of an electric field and the dipolar interactions between particles, submitted to an applied magnetic field in the plane of growth of such structures. The results were produced varying the applied magnetic field and the magnetic moment of the particles and show that the balance between these interactions is an important mechanisms that can be responsible for the changes in shape of the aggregates observed in the experiments.

Evaluation of the impact of information about treatment-related risks in patients receiving blood-derived or recombinant medications.

The aims of the study were to evaluate the impact of a written information about treatment related risks in patient receiving blood derived or recombinant medications. Haemophiliac patients and patients with constitutional or acquired immune deficiencies are concerned by this treatment and these information. Our objectives are to evaluate the efficacy of the written information, the knowledge of the patients about these medications and the psychological, emotional impact if these information. The study is based on questionnaires which specified how the patient treat bleeding episodes, their knowledge about viral safety of blood products, the patient's perception of his or her health status and relationship with the physician. Psychological and emotional status are evaluated with the Hospital Anxiety and Depression Scale. The results show the difficulty to inform patients: if the information generate only limited anxiety in patients with haemophilia or immune deficiencies, we observe that the delivery of a written information got a mediocre effect on overall knowledge. We think that this information must be appropriate for patients and be communicated orally within the patient-physician relationship.

Electrochemical growth of iron and cobalt arborescences under a magnetic field.

Pattern formation in the electrochemical deposition of the magnetic Fe and Co metals from thin layers of Fe(SO4) or Co(SO4) aqueous solutions were investigated in circular geometry and under magnetic field. Sparse arborescences with few thick branches and dense arborescences with many thin branches can be generated when no magnetic field is applied. Unlike for nonmagnetic metals, no tendency towards growth spiraling or asymmetric branching is found out in magnetic field normal to the plane of the growth. The morphology of the deposits appears instead to become more sparse. Under in-plane magnetic field, the sparse arborescences get into a needle morphology, oriented along the field, while the dense arborescences show a circular to rectangular morphology symmetry breaking, one edge of the rectangle being parallel to the field. Unexpected in most instances, these magnetic field effects cannot be understood without invoking the magnetic dipolar interaction inside the magnetized growing aggregate together with its interaction with the applied field.

Prophylactic versus on-demand treatment strategies for severe haemophilia: a comparison of costs and long-term outcome.

A multicentre study was performed to compare clotting factor use and outcome between on-demand and prophylactic treatment strategies for patients with severe haemophilia. Data on treatment and outcome of 49 Dutch patients with severe haemophilia, born 1970-80, primarily treated with prophylaxis, were compared with those of 106 French patients, who were primarily treated on demand. Dutch patients received intermediate dose prophylaxis, for a median duration of 12.7 years. Patients primarily treated with prophylaxis had fewer joint bleeds per year (median 2.8 vs. 11.5), a higher proportion of patients without joint bleeds (29% vs. 9%), lower clinical scores (median 2.0 vs. 8.0), and less arthropathy as measured by the Pettersson score (median 7 points vs. 16 points). Mean annual clotting factor use was equal at 1,488 +/- 783 IU kg-1 year-1 (mean +/- standard deviation) for patients primarily treated with prophylaxis and 1,612 +/- 1,442 IU kg-1 year-1 for patients primarily treated on demand. These findings suggest that, compared with a primarily on-demand treatment strategy, a primarily prophylactic treatment strategy leads to better outcome at equal treatment costs in young adults with severe haemophilia.

Embolized ischemic lesions of toes in an afibrinogenemic patient: possible relevance to in vivo circulating thrombin.

Fibrinogen plays a complex role in hemostasis, thrombosis, and vascular disease. Hyperfibrinogenemia is an independent vascular risk factor and dysfibrinogenemia can provoke thrombosis. Afibrinogenemia is usually responsible for hemorrhagic diathesis, and unexpected ischemic lesions are intriguing. We report the case of an afibrinogenemic patient, who at the age of 30 developed ischemic lesions of the feet related to severe stenosis of the iliac and hypogastric arteries. The biopsy of the iliac artery lesion showed an intense myointimal hyperplasia. We performed standard hemostatic analysis and analyzed the activation markers of platelets and coagulation factors and the kinetics of thrombin generation in the patient and in normal control plasmas treated or not with reptilase. Occlusive arterial lesions were attributed to a disruptive hematoma penetrating the vascular lumen. Thrombin concentration after calcium addition increase markedly in the afibrinogenemic patient and in defibrinated normal plasma, as compared to untreated normal plasma. Thrombin-antithrombin complexes (T-AT) were markedly enhanced while F1+2 prothrombin fragments stayed in the normal range. These results suggested activation of coagulation and in vivo circulating thrombin. Thrombin activates the platelets that secrete growth factors for smooth muscle cells and generate the intimal hyperplasia. Recurrent hemorrhage within the vessel wall might induce injury and local thrombin generation. Thrombin not trapped by the clot is available for platelet activation and smooth muscle cell migration and proliferation. The absence of a protective fibrin cap on the intima might account for intima vulnerability and embolization. Afibrinogenemia appears in this paradoxical situation as a vascular risk factor.

Molecular bases of antithrombin deficiency in French families: identification of seven novel mutations in the antithrombin gene.

We have investigated the molecular bases of familial antithrombin deficiency in eight French families. Eight mutations in the antithrombin coding exons were identified, seven of which were novel mutations. In all cases, individuals were heterozygous for the mutation. We found two small frameshift deletions in exon 3a, leading to type I deficiency. Five missense mutations in exons 3b or 5 also caused type I deficiency and their potential consequences on the antithrombin three-dimensional structure were analysed. The last mutation in exon 4 was associated with a type II 'reactive site' deficiency: a dysfunctional antithrombin that is affected in its interaction with thrombin was present in circulation.

Epidemiological survey of the orthopaedic status of severe haemophilia A and B patients in France. The French Study Group. secretariat.haemophiles@cch.ap-hop-paris.fr.

One hundred and 16 patients contributed to an analysis of the impact of the consequences of severe haemophilia A or B (factor levels < 2%) on orthopaedic status, resources consumed in relation to this status and resultant cost, and quality of life as perceived by the patient, using the MOS 36-Item-Short-Form Health Survey (SF-36). This French cross-sectional study involved outpatients regularly attending a haemophilia treatment centre. Data were collected retrospectively over a period of 1 year by the physician of the haemophilia treatment centre. Patients had a mean age of 23, and consisted of 50% students, 25% salaried workers, 17.2% with no professional activity and 7.8% physically impaired; 82.8% of them had type A haemophilia. Mean pain score was 2.5 per patient for the six main joints; 7.7 for the clinical score and 18.8 for the radiological score, with a mean number of bleeds of 16.3 per year per patient. During the year prior to inclusion, and because of their orthopaedic status, 22.4% of patients were hospitalized, 76.7% attended for an outpatient visit and 76.7% required at least one special investigation; 97.4% received replacement therapy, 41.4% required treatment for joint pain and 42.2% orthopaedic equipment. The less affected dimensions were the physical function (76.8 +/- 22. 2) and the social relations (76.1 +/- 23.1). Least good quality of life scores concerned the pain (60.2 +/- 25.2), perception of general health (59.3 +/- 23.1) and vitality (57.8 +/- 19.5) dimensions. The age was a discriminant criterion since quality of life was better in patients of the 18-23 age group for five dimensions. Mean annual treatment costs of a patient with severe haemophilia were determined as 425 762 French francs ($73 029). Loss of production was estimated at a mean of 4609 French francs ($791) per active patient over the course of the year. Results showed indirect evidence of the usefulness of early home treatment.

A retrospective study on chemical and radioactive synovectomy in severe haemophilia patients with recurrent haemarthrosis.

Between 1970 and 1994, 116 chemical and 90 radioactive synovectomies were performed in 107 patients with severe haemophilia and two with type 3 von Willebrand's disease. The products used were osmic acid (OA) in 100 cases, 90-Yttrium in 35 cases, 186-Rhenium in 48, 169-Erbium in two, hexacetonide triamcinolone in 16 and radioactive gold in five cases. The use of radioactive colloids is not allowed in France in patients under 15 years of age. Twenty-nine patients had more than one synovectomy per joint. All patients were evaluated for 6 months post-synovectomy, using both a clinical and a radiological score. Six months after synovectomy, a good or excellent result was obtained for 81% of the joints treated with isotopes, compared with 44% of those treated with OA, P<0.001. This superiority of isotopes over osmic acid was still observed after 6 months for the 89 joints that were re-evaluated, with follow-up ranging from 1 to 9 years. It was possible to calculate a radiological score in 84 cases. With OA the best results were from the joints with the lowest scores pre-synovectomy (<7). No correlation could be established between the clinical and the radiological scores, due to the small size of the sample. In summary: (1) chemical and radioactive synovectomy are simple and safe procedures for haemophilic arthropathy, (2) in our series, after 6 months the efficacy of isotopic synovectomy was greater than that of chemical synovectomy, and this benefit seems to persist after 6 months, and up to 9 years in the group of patients with longer-term follow-up.

Acquired hemophilia secondary to factor VIII inhibitors after pregnancy.

We report the case of a 26 year-old woman who developed acquired hemophilia secondary to factor VIII inhibitors, two months after a normal pregnancy. The initial hemorrhagic event was a spontaneous deep muscular hematoma mimicking a deep venous thrombosis. This observation was marqued by the apparition of antibodies against porcin factor VIII under treatment by porcin factor VIII. Intravenous immunoglobulin was ineffective, then cyclophosphamide was necessary to control the disease.

Nonsurgical synovectomy in the treatment of arthropathy in Von Willebrand's Disease.

Von Willebrand's disease is the most common inherited bleeding disorder, with an overall prevalence in the general population of 0.8% to 1.3%. Hemarthrosis occurs mainly in the severest forms of the disease (type III), with a frequency of 3.5% to 11%, and can cause severe arthropathy similar to that seen in hemophilia. We retrospectively reviewed our experience with nonsurgical synovectomy in the treatment of recurrent hemarthrosis with arthropathy in patients with von Willebrand's disease. Four of our six patients had type III disease and the remaining two had type II disease. The age range was 13 to 63 years. The frequency of hemarthrosis prior to synovectomy was one to four per month. One (n = 2) or both (n = 1) knees were treated in 4 cases, one (n = 1) or both (n = 1) ankles in 3 cases and an elbow in one case. We used yttrium 90 in a dose of 5 mCi for one knee, rhenium 186 in a dose of 2 mCi for two ankles and the elbow and osmic acid for two knees and one ankle. Clinical and radiological results were evaluated six months after synovectomy using the World Federation of Hemophilia score. Radiologic lesions remained stable and clinical manifestations improved in every case (p < 0.05). Five patients achieved a complete remission. Safety was satisfactory. The clinical efficacy of synovectomy done, using radiocolloids or osmic acid in arthropathy due to von Willebrand's disease, seems similar to that in hemophilia.

Nonviolent (empathic) communication for health care providers.

The purpose of Nonviolent or Empathic Communication Training is to facilitate the flow of information necessary for people to work cooperatively and resolve differences effectively. Such training is widely used in medical communities where the communication with patients and the cooperation between team members are of critical importance for the effectiveness of the treatment. Communication skills are of particular importance for health care providers dealing with patients having chronic diseases such as haemophilia. In addition to the difficulties inherent to the chronicity of the disease, the HIV contamination has dramatically impaired the relationships between patients and health care providers, creating a lot of pain, still alive in both parties. The purpose of this presentation is to offer to health care providers and patients some tools to deal with their feelings and restore effective, compassionate and fulfilling communication.

[From heparin to heparins: toward new therapeutic perspectives?]. / De l'héparine aux héparines: vers de nouvelles perspectives thérapeutiques?

Heparin is mainly known for its anticoagulant action, but today other biological effects are investigated. With the low molecular weight heparin fractions (LMWH), more homogenous, a more detailed study of the mechanism of action of heparins can be made. The anticoagulant action of heparin is mainly antithrombin III (AT III) dependent and the binding site of AT III on the heparin molecule has been recently identified. LMWH have a lower anticoagulant (anti-IIa) activity, and a relatively higher anti-Xa activity (ratio anti-Xa/anti-IIa = 5 to 10 for LMWH and 1 for standard heparin). The antithrombotic action of heparins is not strictly correlated to their anticoagulant activity. Other mechanisms of action, such as interactions with vascular endothelial cells and the fibrinolytic system may contribute to the antithrombotic action of heparins. New therapeutical possibilities are currently under investigation. Inhibition of vascular smooth muscle cells growth by heparin suggest a possible control of the atherosclerotic process by heparin. Moreover, heparin and its derivatives might be involved in the regulation of the cellular growth process.

Endothelial binding sites for heparin. Specificity and role in heparin neutralization.

The specificity of endothelial binding sites for heparin was investigated with heparin fractions and fragments differing in their Mr, charge density and affinity for antithrombin III, as well as with heparinoids and other anionic polyelectrolytes (polystyrene sulphonates). The affinity for endothelial cells was estimated by determining I50 values in competition experiments with 125I-heparin. We found that affinity for endothelial cells increases as a function of Mr and charge density (degree of sulphation). Binding sites are not specific receptors for heparin. Other anionic polyelectrolytes, such as pentosan polysulphates and polystyrene sulphonates, competed with heparin for binding to endothelial cells. Fractions of standard heparin with high affinity for antithrombin III also had greater affinity for endothelium. However, these two properties of heparin (affinity for antithrombin III and affinity for endothelial cells) could be dissociated. Oversulphated heparins and oversulphated low-Mr heparin fragments had lower anticoagulant activity and higher affinity for endothelial cells than did their parent compounds. Synthetic pentasaccharides, bearing the minimal sequence for binding to antithrombin III, did not bind to endothelial cells. Binding to endothelial cells involved partial neutralization of heparin. Bound heparin exhibited only 5% and 7% of antifactor IIa and antifactor Xa specific activity, respectively. In the presence of 200 nM-antithrombin III, and in the absence of free heparin, a limited fraction (approx. 30%) of bound heparin was displaced from endothelial cells during a 1 h incubation period. These data suggested that a fraction of surface-bound heparin could represent a pool of anticoagulant.

Modulation of endothelial cells growth induced by heparin.

We have previously shown that heparin was bound and internalized by cultured human endothelial cells. In this study, we have investigated the effect of heparin on endothelial cells growth. We found that heparin inhibited 3H-thymidine uptake as well as actual cell growth in a dose-dependent manner in the presence of low concentrations of human serum. Inhibition was maximal at 1% serum concentration and was abolished at 10%. Chasing experiments supported the role of membrane-bound heparin in this inhibition. Low molecular weight heparin fractions, or pentosan polysulfate, were equally effective in inhibiting 3H-thymidine uptake. On the other hand, the simultaneous addition of heparin and ECGS was synergic in stimulating 3H-thymidine uptake. These results suggest a modulatory role of heparin in endothelial cells growth.

Binding and endocytosis of heparin by human endothelial cells in culture.

Binding of heparin and low molecular weight heparin fragments (CY 222, Mr range 1500-8000) to human vascular endothelial cells was studied. Primary culture of human umbilical vein endothelial cells and either 125I or 3H-labeled heparin or [125I]CY 222 were used. Slow, saturable and specific binding was found. No other tested glycosaminoglycan, excepting a highly sulfated heparan fraction, was able to compete for heparin binding. Two groups of binding sites for [3H]heparin could be distinguished: one with high affinity (Kd = 0.12 microM) and another with lower affinity (Kd = 1.37 microM) and a relative large capacity of binding (1.16 X 10(7) molecules/cell) was calculated. The Kd for unlabeled heparin, as calculated from competition experiments, was 0.23 microM. Much lower affinity was calculated for unlabeled low molecular weight heparin fragments CY 222 (Kd = 4.3 microM) from competition experiments with [125I]CY 222. The binding reversibility was only partial for unfractionated heparin. Even by chasing with unlabeled compound, a fraction of 25-30% was not dissociable from endothelial cells. This fraction was much lower if incubation was carried out at 4 degrees C. The addition of basic proteins (histones) to the incubation medium greatly enhanced the undissociable binding at 37 degrees C, but not at 4 degrees C. The undissociable fraction of heparin was not available to degradation by purified microbial heparinase. These results suggest that a fraction of bound heparin is internalized by the vascular endothelium.

Hypercalcemia in chronic myelogenous leukemia: evidence for excessive parathyroid hormone secretion.

Hypercalcemia was associated with osteolytic bone lesions in a 60-year-old woman with chronic myelogenous leukemia in the accelerated phase. Using highly specific antisera to parathyroid hormone, radioimmunoassays disclosed elevated levels of carboxyl-terminal (53-84) and intermediate (44-68) fragments. In addition, concomitant variations of serum calcium level and leukocyte counts, increased urinary c-AMP excretion, morphological integrity of parathyroid glands, and absence of bone resorbing activity in myeloblast culture supernatants are consistent with the hypothesis that the humoral hypercalcemia was due to the excessive production of PTH. This production may have been ectopic, although no PTH secretion was demonstrated in myeloblast culture supernatants.

Binding of heparin and low molecular weight heparin fragments to human vascular endothelial cells in culture.

The interaction of standard heparin and some low molecular weight heparin fragments (CY 222, mw 1,500-8,000 daltons) with human vascular endothelium in culture was studied using both 125I and 3H labeled ligands. A specific and saturable binding was shown for both labeled standard heparins. Two populations of binding sites for 3H-standard heparin could be distinguished: one of high affinity (KD = 0.12 microM), and another of lower affinity (KD = 1.37 microM). Total binding capacity was in the order of 10(7) molecules per cell. The same high level of affinity was calculated for unlabeled compounds from competition experiments with 125I-standard heparin. No other glycosaminoglycans, except a highly sulfated heparan (fraction IIA) could compete for heparin binding sites. A specific binding was also shown for 125I-CY 222. The affinity of unlabeled CY 222 was approximately ten times lower than that of unfractionated heparin. However, CY 222 could compete for approximatively 30% of standard heparin binding. Binding was not completely reversible. Even in the presence of a large excess of unlabeled compounds, a fraction of 25% of radioactive heparins remained bound to the endothelium. This fraction was three times lower if incubation was carried out at +4 degrees C, suggesting a possible incorporation of heparin into the endothelial cells.