Tandem inversion duplication within F8 Intron 1 associated with mild haemophilia A.

In approximately 90% of mild haemophilia A (HA) patients, a missense mutation can be identified using complete gene sequencing. In this study, multiplex ligation-dependent probe amplification analysis was performed as a second step in 10 French-speaking Belgian with mild HA presenting no detectable causal mutation by complete sequencing of the factor VIII (FVIII) (F8) gene's 26 exons and its 1.2 kb of contiguous promoter sequence. This gene dosage technique enabled the detection of exon 1 duplications of F8 in three apparently unrelated subjects. Using array-comparative genomic hybridization, breakpoint analysis delimited the duplication extent to 210 kb in the F8 intron 1 and VBP1 gene intragenic position. We postulated that the rearrangement responsible for this duplication, never before reported, could be attributed to a symmetrical tandem inversion duplication, resulting in a large 233 kb rearrangement of F8 intron 1. This rearranged intron should lead to the production of a small number of normal mRNA transcripts in relation to the mild HA phenotype. Our analysis of the entire F8 mRNA from index case 1, particularly the segment containing exons 1-9, revealed normal amplification and sequencing. Reduced plasma FVIII antigen levels caused by cross-reacting material is associated with a quantitative deficiency of plasma FVIII. Male patients were unresponsive to desmopressin (1-deamino-8-D-arginine vasopressin). All patients displayed identical F8 haplotypes, despite not being related, which suggests a possible founder effect caused by a 210 kb duplication involving F8 exon 1.

Neonatal haemoglobinopathy screening in Belgium.

BACKGROUND: A neonatal haemoglobinopathy screening programme was implemented in Brussels more than a decade ago and in Liège 5 years ago; the programme was adapted to the local situation. METHODS: Neonatal screening for haemoglobinopathies was universal, performed using liquid cord blood and an isoelectric focusing technique. All samples with abnormalities underwent confirmatory testing. Major and minor haemoglobinopathies were reported. Affected children were referred to a specialist centre. A central database in which all screening results were stored was available and accessible to local care workers. A central clinical database to monitor follow-up is under construction. RESULTS: A total of 191,783 newborns were screened. One hundred and twenty-three (1:1559) newborns were diagnosed with sickle cell disease, seven (1:27,398) with beta thalassaemia major, five (1:38,357) with haemoglobin H disease, and seven (1:27,398) with haemoglobin C disease. All major haemoglobinopathies were confirmed, and follow-up of the infants was undertaken except for three infants who did not attend the first medical consultation despite all efforts. CONCLUSIONS: The universal neonatal screening programme was effective because no case of major haemoglobinopathy was identified after the neonatal period. The affected children received dedicated medical care from birth. The screening programme, and specifically the reporting of minor haemoglobinopathies, has been an excellent health education tool in Belgium for more than 12 years.

[Paradox: when a prothrombotic disorder is responsible for an upper gastrointestinal bleeding. Case report of hepatoportal sclerosis]. / Paradoxe: lorsqu'un état prothrombotique est responsable d'une hémorragie digestive. Observation d'un cas de sclérose hépatoportale.

Variceal bleeding is frequently the initial presentation of a previously unknown cirrhosis. Portal hypertension and its complications without liver cirrhosis should raise the possibility of presinusoidal portal hypertension, and the diagnosis of hepatoportal sclerosis. These patients need to be investigated for coagulation disorders. A hypercoagulable state is often associated. Risks and benefits of anticoagulation should be further investigated in these patients.

Lactoferrin: its role as a regulator of human granulopoiesis?

Lactoferrin has been proposed recently as a physiological regulator of the granulocyte-monocyte progenitor (CFU-GM). This glycoprotein, when saturated with iron, has been said to limit the CFU-GM growth by decreasing production and release of colony stimulating activity by monocytes and macrophages. Human milk lactoferrin saturated with iron, at concentrations ranging from 10(-8) M, was added either to endogenously stimulated bone marrow cells or to mononucleated cells used as feeder layers for adherent cell-depleted marrow. Irrespective of the concentration of lactoferrin within the culture system used, no significant inhibition of the CFU-GM growth was observed. Moreover, the CFU-GM stimulating activity of medium conditioned by a 4 day incubation of 1 X 10(6) mononucleated blood cells in the presence or in the absence of lactoferrin was the same. Various possible explanations for not confirming the reported inhibiting activity of iron-saturated lactoferrin were explored: (a) masking inhibition of the system by prostaglandin E2 (PGE2), (b) masking inhibition of the system by bovine lactoferrin present in the fetal calf serum, (c) preinhibition of the system by leukemic-associated inhibitory activity possibly present in the culture system, (d) the iron and calcium content of the culture medium used, (e) the fixation of lactoferrin to plastic compounds, (f) the source of the human lactoferrin used, and (g) the marrow cell separation methods used. None of these factors was shown to play a role in vitro in the activity of lactoferrin and thus no evidence was found for a significant role of lactoferrin in the regulation of human granulopoiesis.

Effect of 4-hydroperoxycyclophosphamide on leukemic and normal human myeloid progenitor cells.

The sensitivity of myeloid progenitor cells from normal subjects (N-CFU-GM) and from leukemic patients in complete remission (LR-CFU-GM) to 4-hydroperoxycyclophosphamide (4-HC) were compared to the sensitivity of leukemic progenitor cells (L-CFU) to this drug. The results were expressed as the dose of 4-HC needed to kill 90% (TD 90) of the progenitor cells. The mean TD 90 were respectively for N-CFU-GM : 59 (+/- 11 S.E.M.) nM ml-1 and for L-CFU 79 (+/- 6 S.E.M.) nM ml-1. Thus, L-CFU were equally sensitive to 4-HC as N-CFU-GM. Moreover, the mean TD 90 for LR-CFU-GM was 87 (+/- 5 S.E.M.) nM ml-1. Thus, the sensitivity of N-CFU-GM and LR-CFU-GM did not differ significantly from that of L-CFU. These results are not encouraging for the use of 4-HC in vitro to eliminate the residual leukemic cells from autologous bone marrow of AML patients in complete remission. The sensitivity of L-CFU was modified neither by previous cytoreductive therapy (different from cyclophosphamide) nor by the time elapsed since diagnosis of AML.

Lactoferrin: no evidence for its role in regulation of CSA production by human lymphocytes and monocytes.

Lactoferrin (LF) has been recently proposed as a physiologic regulator of the granulocyte monocyte progenitor (CFU-GM). This glycoprotein, when saturated with iron, has been said to limit CFU-GM growth by decreasing production and release of colony stimulating activity (CSA) by monocytes and macrophages. Human milk LF saturated with iron, at concentrations ranging from 10(-18) to 10(-8) M was added either to endogenously stimulated bone marrow cells or to mononucleated cells used as feeder layers for adherent cell-depleted marrow. Irrespective of the concentration of LF within the culture system used, no significant inhibition of CFU-GM growth was observed. Moreover, the CFU-GM stimulating activity of medium conditioned by a 4-day incubation of 1 X 10(6) mononucleated blood cells in the presence or in the absence of LF was the same. Various possible explanations for not confirming the reported inhibiting activity of iron saturated LF were explored: 1) masking inhibition of the system by prostaglandin E2 (PGE2), 2) masking inhibition of the system by bovine LF still detectable in the fetal calf serum after heating, 3) preinhibition of the system by leukemic-associated inhibitory activity (LIA) possibly present in the culture system, 4) the iron and calcium content of the culture medium used, 5) the fixation of LF to plastic compounds, 6) the source of the human LF used, 7) the marrow cell separation methods used. None of these factors was shown to play a role in vitro in the activity of LF and thus no evidence was found for a significant role of LF in the regulation of CSA production by monocytes. Peripheral blood human monocytes isolated by elutriation and incubated in albumin free medium in the presence of either 125I-LF or colloidal gold-labeled LF showed no LF binding.

Increased levels of myeloid progenitor cells in the blood of patients with metastatic invasion of the marrow.

Granulocyte-macrophage clusters and colony-forming cells (CFU-C) in the peripheral blood have been studied in 26 cancer patients with neoplastic bone marrow involvement. The concentration of CFU-C in the blood of normal individuals and of cancer patients with no bone marrow invasion, ranged from 0 to 99 ml. In contrast, out of 27 cancer patients with marrow invasion, 9 (35%) showed a significant increase of blood CFU-C (100 to 21000/ml) and of those 5 (19%) showed an increase of blood colonies (41 to 9000/ml). There was a strong correlation between increased CFU-C or colony concentration and the presence of myeloid or/and erythroid immature cells in the peripheral blood. On the other hand, there was no apparent correlation between an increased CFU-C level and anaemia or abnormal blood leucocyte count or marrow fibrosis. These observations suggest that bone marrow involvement by neoplastic cells may cause spatial redistribution of the granulocyte macrophage progenitor cells.

Granulocyte-macrophage progenitor cell preservation at 4 degrees C.

Eighteen bone marrows collected from patients without haematological diseases and from normal subjects were tested for the effects of 4 d storage at 4 degrees C on CFU-C growth. Results indicate that unfractionated bone marrow cells may be stored at 4 degrees C for 4 d with 97% +/- 8 SEM recovery of the CFU-C evaluated by the agar culture assay. On the other hand, the same preservation procedure on peripheral blood CFU-C of 13 normal subjects yielded only 5% +/- 2 SEM recovery of in vitro growth capacity. The present results have practical implications. They might be exploited to preserve bone marrow CFU-C for transplantation therapy or laboratory investigation. In contrast this single preservation procedure seems not appropriate for preserving blood CFU-C.

Effect of 2 anti-arrhythmic drugs aprindine and moxaprindine on the replication capacity of murine and human haemopoietic cells.

Aprindine, a potent anti-arrhythmic agent, occasionally seems responsible for agranulocytosis. In order to study its potential haematological toxicity, 3 different in vitro tests were used: (a) the capacity of human and mice bone marrow to incorporate tritiated thymidine (3HTdR), (b) the capacity of stimulated human blood lymphocytes to incorporate 3HTdR and (c) the capacity of human granulocyte-macrophage stem cells to form colonies in agar. For all these tests aprindine was found to be toxic at concentrations close to the clinical therapeutic serum concentration. Moxaprindine, chemically very close to aprindine exhibits also an anti-arrhythmic activity. It was examined in the same tests in parallel with the study af aprindine. Moxaprindine also exhibited haematological toxicity in the tests but at a significantly higher concentration, approximately twice that of aprindine. Assuming that these in vitro tests are relevant to the in vivo haematological toxicity, moxaprindine could be considered a clinically safer anti-arrhythmic agent than aprindine.

Scientific basis and criticism of current therapy of acute leukemia.

The factors which are thought to determine the response of acute leukemia (AL) to therapy are: 1) tumor size 2) drug dose 3) sensitivity to drug, 4) scheduling of drugs and 5) suppression of normal hemopoiesis. Each of these factors is considered in terms of the scientific data supporting their importance. Inability to measure the size of the tumor mass during all phases of treated AL continues to weaken rational strategies for therapy especially maintenance chemotherapy. Increasing the drug dose improves cell kill and potentially the cure rate up to the limits of toxicity. These limits may be extended by bone marrow transplantation. Various systems to study the drug sensitivity of leukemic cells are in experimental use, including stem cell assays but as yet they do not give a guide to altering therapy. The scheduling of multiple drugs is designed to increase cell kill by recruitment into the cycle, but "sanctuaries" appear to exist for resting cells. The suppression of normal hemopoiesis apparently due to leukemia-associated inhibitors is associated with favorable prognosis in childhood ALL but use of this information to improve treatment protocols is still unclear.

Usefulness of cell kinetics for staging of chronic myeloid leukemia?

In the blood, the labelling index of the immature myeloid cells of one patient out of three decreased progressively from diagnosis to blastic crisis. This parameter deserves more investigation. In the marrow however, the 3H thymidine labelling indexes of the myeloid cells were not useful in predicting the blastic transformation of CML. The colony inhibiting activity of the PMN in CML neither was found to be useful in staging the disease.