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Biomedical subjects

G A de Vaan

Publications and source records attributed to G A de Vaan.

At least 19 recordsLinked to original sources
PubMed1999

Intensive treatment of children with acute lymphoblastic leukemia according to ALL-BFM-86 without cranial radiotherapy: results of Dutch Childhood Leukemia Study Group Protocol ALL-7 (1988-1991).

In The Netherlands from July 1988 to October 1991, children (0 to 16 years of age) with de novo acute lymphoblastic leukemia (ALL) were treated according to protocol ALL-7 of the Dutch Childhood Leukemia Study Group (DCLSG). In this protocol, chemotherapy and treatment stratification were identical to the ALL-BFM-86 protocol (Reiter et al, Blood 84:3122, 1994), but cranial irradiation was restricted to patients with initial central nervous system (CNS) involvement. Patients were stratified into 3 risk groups, based on leukemia cell mass and response to initial treatment: standard-risk group (SRG), risk group (RG), and experimental group (EG). As in ALL-BFM-86, a randomized study on late intensification (protocol S) was performed in RG patients, and during the study (since October 1990), early reinduction treatment (protocol II) was introduced for SRG patients. Treatment duration for all patients was 18 months. Two hundred eighteen children entered the study: 74 SRG, 127 RG, and 17 EG patients. The overall complete remission (CR) rate was 98%. The 5-year event-free survival (EFS) for all DCLSG ALL-7 patients was 65. 3% (standard error [SE] 3.2%), which was significantly different from the 73% (SE 1%) 5-year EFS achieved in the ALL-BFM-86 study (P =.02, Z-test). However, restricting the analysis to SRG patients receiving protocol II with a total duration of treatment of 18 months, the 5-year EFS rates were 64.6% (SE 4.0%) and 67% (SE 4%), respectively, and no significant difference could be established (P =.67, Z-test). The 5-year EFS rates for SRG, RG, and EG patients were 63.5% (SE 5.6%), 66.6% (SE 4.2%), and 63.3% (SE 12.0%), respectively. SRG patients receiving protocol II fared better than patients not receiving protocol II (5-year EFS 76.7% [SE 7.7] and 54. 5% [SE 7.5], respectively). No difference in 5-year EFS was observed in RG patients randomized to receive or not to receive late intensification with protocol S. The overall CNS relapse rate at 5 years was 5.5%. The incidence rate at 5 years was 11.4% in SRG patients not receiving protocol II, whereas no CNS relapses occurred in SRG patients receiving protocol II. Six children died in first complete remission and 2 children developed a second malignancy (thyroid carcinoma and acute nonlymphoblastic leukemia). Systemic high-dose methotrexate (MTX) and intrathecal chemotherapy is a safe and effective method of CNS prophylaxis in the context of BFM-oriented treatment for all children with ALL, regardless of the risk group (with the possible exception of T-ALL patients with high white blood cell counts). The results of the DCLSG ALL-7 study confirm those of the ALL-BFM-86 study showing that early reinduction with protocol II is essential in the treatment of SRG patients and that late intensification with protocol S does not improve the prognosis for RG patients.

Adolescent↗
PubMed1996

CD4 deficiency in myelodysplastic syndrome with monosomy 7.

UNLABELLED: We describe a patient with myelodysplastic syndrome with monosomy 7 presenting with a T-cell defect. He suffered from infections from the age of 10 years, when a CD4 deficiency and impaired lymphoproliferative responses in vitro were found. The only symptom of a myelodysplastic syndrome at that time was thrombocytopenia with giant platelets. Monosomy 7 was found in the bone marrow cells. At the age of 11 years he developed other characteristics of monosomy 7 including splenomegaly and anaemia. Some months later leukaemia was diagnosed. CONCLUSION: In non-HIV CD4 deficiency myelodysplastic syndrome has to be considered.

CD4 Antigens↗
PubMed1995

Late effects among long-term survivors of childhood acute leukemia in The Netherlands: a Dutch Childhood Leukemia Study Group Report.

Late events and side effects are reported in 392 children cured of leukemia. They originated from 1193 consecutively newly diagnosed children between 1972 and 1982, in first continuous complete remission for at least 6 y after diagnosis, and were treated according to Dutch Childhood Leukemia Study Group protocols (70%) or institutional protocols (30%), all including cranial irradiation for CNS prophylaxis. Data on late events (relapses, death in complete remission, and second malignancies) were collected prospectively after treatment; late side effects were retrospectively collected by a questionnaire, completed by the responsible pediatrician. The event-free survival of the 6-y survivors at 15 y after diagnosis was 92% (+/- 2%). Eight late relapses and nine second malignancies were diagnosed, two children died in first complete remission of late toxicity of treatment, and one child died in a car accident. The most important long-term side effects reported were learning disabilities (50%), short stature, obesity, and delayed pubertal development. No increase in the incidence of cardiovascular, pulmonary, urogenital, or gastrointestinal tract diseases or an increased vulnerability of the musculoskeletal system was found. However, prolonged follow-up is necessary to study the full-scale late effects of cytostatic treatment and radiotherapy administered during childhood.

Adolescent↗
PubMed1994

Juvenile xanthogranuloma and acute leukemia: a case report.

Juvenile xanthogranuloma (JXG) is a rare benign disease of the skin. It is seen in combination with juvenile chronic myelo-monocytic leukemia (JCML) and/or neurofibromatosis type 1 (NF1). The association with acute lymphoblastic leukemia is hardly mentioned in the literature. A case report of this rare combination is described and a review of the literature is given.

Child, Preschool↗
PubMed1992

Iatrogenic IgG2 deficiency in a leukaemic child. A case report.

A girl with acute non-lymphoblastic leukaemia was treated with immunosuppressive chemotherapy. After cessation of therapy she had three consecutive episodes of infection due to Streptococcus pneumoniae from which she recovered and was shown to have developed a combined deficiency of both IgG2 and IgG4. The patient eventually relapsed and died 3 years after the initial diagnosis. The importance of measuring IgG subclasses in patients treated with immunosuppressive chemotherapy is discussed.

Bacteremia↗
PubMed1990

Prevalence of naevocytic naevi after chemotherapy for childhood cancer.

The frequency of naevocytic naevi (moles) in patients with childhood haematologic malignancies was studied. All patients had received multiple chemotherapy. The majority had also received cranial irradiation as part of their central nervous system leukaemia/lymphoma prophylaxis. Total body mole counts of the patients were compared with those of their healthy brothers and sisters. The median number of moles in the patient group was 20.0 (n = 79), in the healthy sibs 11.0 (n = 88). In two subgroups mole counts of male and female patients were compared with those of their closet brother or sister. There were 19 male and 19 female pairs for comparison. Median numbers of moles were significantly higher in both patient groups than in the controls (P less than 0.05). It is suggested that multiple chemotherapy (and/or cranial irradiation) may induce or activate naevocytic naevi. These findings may have important implications with regard to the aetiology of melanoma.

Adolescent↗
PubMed1989

Mild course of mumps in patients with acute lymphoblastic leukaemia.

Few details exist on the course of mumps during cytostatic treatment. We therefore describe our observations on the course of mumps seen between 1974 and 1988 in eight children suffering from acute lymphocytic leukaemia (ALL). Our data suggest that in malignant disease the course is rarely severe and that the infection often remains subclinical, as in healthy children. Mumps was accidentally diagnosed by routine lumbar puncture in four of the eight patients. Literature data suggest that the intrinsic low cytopathological effect of the virus, together with a parallelism between T cell response and clinical severity, may explain the usual mild course in immunodepressed patients, contrasting with the severe course of measles and Varicella zoster.

Child↗
PubMed1988

Pyoderma gangrenosum in acute myeloid leukaemia during immunosuppression.

We describe a patient who developed pyoderma gangrenosum during the remission phase of acute myeloid leukaemia whilst receiving maintenance therapy with methotrexate and 6-mercaptopurine. The spontaneous resolution of these skin lesions following discontinuation of chemotherapy suggests that these drugs may be of major significance in the aetiology of pyoderma gangrenosum. Nevertheless, 27 months later, a relapse of the leukaemia followed. Although pyoderma gangrenosum occurred during clinical remission, we cannot rule out a synergism of leukaemia and chemotherapy in its pathogenesis.

Adult↗
PubMed1988

[Biochemical and clinico-pharmacological aspects of antimetabolites in the treatment of leukemia].

Methotrexate (MTX) and 6-mercaptopurine (6MP) have been used since 30 years in the maintenance treatment of acute lymphoblastic leukemia (ALL) of childhood. A synergistic effect of this combination was demonstrated in mouse and childhood leukemia. In this article an overview is given of our investigations, concerning the biochemical basis of this synergism. This synergism is caused by a selective inhibition of the purine de novo synthesis in malignant lymphoblasts by MTX, associated with an enhanced intracellular uptake of 6MP. Pharmacokinetic studies of MTX in various schemes of prophylactic central nervous system treatment in ALL are discussed. Treatment with 24-hr infusions of MTX in a dosage of 5 g/m2, as recommended in the new BFM-86/SNWLK ALL VII protocol, seems to be optimal. Pharmacokinetic studies of intravenous 6MP infusions demonstrated a good cerebral fluid penetration. Exploiting the synergistic action of the combination of MTX and 6MP may offer an improvement of the prophylactic central nervous systems treatment in ALL in the future, using intravenous administration of both MTX and 6MP.

Child↗
PubMed1986

6-mercaptopurine: high-dose 24-h infusions in goats.

In vitro investigations have indicated the need for both prolonged exposure to 6-mercaptopurine (6MP) and the use of high concentrations to achieve maximal cell kill. After the customary oral administration the bioavailability of 6MP appeared to be low, and i.v. bolus injections resulted in short-lived high concentrations of 6MP, so prolonged infusions seemed rational. To test the feasibility of this approach 24-h infusions were given to goats. We used our improved HPLC method to quantitate 6MP and 6MP riboside (6MPR) in plasma, CSF, and urine. The concentrations of 6MPR were in excess of those of 6MP. Since 6MPR can easily be converted to 6MP, 6MPR acts as a depot for 6MP. Penetration of both 6MP and 6MPR into CSF was excellent. Of the total dose administered, 38% to 68% could be accounted for in the urine, with about equal amounts of 6MP and 6MPR. At doses of 20 and 10 mg kg-1 h-1 total concentrations of 6MP and 6MPR in excess of 100 microM were reached during 24-h infusions. However, all three experimental animals died due to toxicity. A dose of 2 mg kg-1 h-1 was tolerated; the total steady state concentration of 6MP and 6MPR in two experiments was about 10 microM. We conclude that the prolonged infusion of 6MP is feasible, and in view of the excellent penetration of 6MP and 6MPR into CSF, studies using prolonged infusions of thiopurines are warranted in man.

Administration, Oral↗
PubMed1986

6-Mercaptopurine: total body autoradiograms and plasma concentration-time curves of 6MP and metabolites from marmoset monkeys.

To study the body distribution of 6-mercaptopurine (6MP), [8-14C]6MP was given by infusion to 2 marmoset monkeys at a dose rate of 5 mg/kg body weight/h for 1 and 4 h, respectively. Both experimental animals were sacrificed 2 h after the end of the drug infusion and instantly frozen at -70 degrees C. Whole-body sagittal sections were made later. Blood samples were obtained regularly during the experiments to quantitate 6MP, 6MP riboside (6MPR), 6-thioxanthine, and 6-thiouric acid in plasma. The autoradiograms revealed extensive distribution of the 14C label. High levels of radioactivity were seen in liver, bile, and intestinal contents. Labeling of the central nervous system and bone marrow was obvious. The plasma concentration-time curves of 6MP and 6MPR attained steady-state concentrations of 30-40 microM and 6-12 microM, respectively. After stopping the infusion of the drug, the concentrations of 6MP and 6MPR became equal. 6MPR contributes to the biological effect of 6MP, as degradation of 6MPR results in 6MP. In studies on the pharmacokinetics and dynamics one should try to include all relevant metabolites of 6MP, both in plasma and in the cells.

Animals↗
PubMed1985

6-Thioguanine: high-dose 2-H infusions in goats.

6-Thioguanine (6TG) is poorly absorbed after oral administration. Bolus injections of 6TG result in high peak concentrations with relatively short-lived plasma concentrations. In vitro studies have shown the importance of prolonged exposure to 6TG. Therefore we administered 6TG by infusion at a dose rate of 2 mg/h over 2 h. In three goats we determined the plasma concentration-time curves of 6TG and its riboside (6TGR). A steady state was reached for 6TG and was almost reached for 6TGR within the 2 h of infusion. In one experiment we obtained several samples of CSF and observed good penetration of 6TG and 6TGR into CSF. Urinary excretion of 6TG and 6TGR was also quantitated. The amount of drug and metabolite excreted later than 4 h after the end of the infusion was negligible. By infusing 6TG, the problems of both erratic absorption after oral administration and acute renal toxicity after bolus injection, can be averted. In our opinion prolonged infusions of 6TG may be of advantage in humans suffering from actively proliferating malignant diseases, and thus should be studied.

Animals↗
PubMed1984

Transient erythroblastopenia of childhood. A review of 22 cases.

In the period 1975-1983 22 patients, aged 4-36 months were seen with severe transient normochromic, normocytic anaemia caused by a transient erythroblastopenia. In 20 patients bone marrow aspirations were obtained; they showed erythroblastopenia. In ten cases we observed young lymphoid cells, suggesting a diagnosis of acute lymphoblastic leukaemia. One patient suspected of a leukaemia, was studied in more detail. All patients showed reticulocytopenia. MCV and HbF were within normal range. During recovery reticulocytosis and higher levels of HbF were found. Except for blood transfusion in most patients, therapy (e.g. corticosteroids) was not necessary. Spontaneous recovery is a feature of this kind of erythroblastopenia, contrasting with congenital hypoplastic anaemia.

Anemia, Aplastic↗
PubMed1983

Malignant histiocytosis. Clinical and cytogenetic studies in a newborn and a child.

Malignant histiocytosis (MH) was diagnosed on the cytologic and cytochemical features of the malignant cells present in bone marrow smears from an infant and a child. The diagnosis of MH was confirmed by light and electron microscopic studies on bone marrow and skin biopsy specimens, and bone marrow and liver biopsy specimens, respectively. Both patients showed a deterioration while receiving prednisone monotherapy, but they responded well to a combination of vincristine and cyclophosphamide. The infant has remained disease-free for 52+ months now, but the child died of a relapse 11 months after diagnosis. Cytogenetic studies of blood and/or bone marrow cells were performed before treatment. In the infant, a pathologic cell line with a translocation t(8;16)(p11;p13) was found; this abnormality was no longer present after remission was obtained. In the second patient, a hyperdiploid cell line with major karyotypic anomalies was found. When studied in relapse and shortly before death, additional chromosomal abnormalities were seen. The data from this study show that prednisone should be used with caution in MH, and that it should be omitted from combination chemotherapy when adverse effects are noted during short-term monotherapy. Also, cytogenetic studies should be performed more often in MH to determine the significance and possible nonrandomness of chromosomal abnormalities in this disease.

Antineoplastic Agents↗