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S Wiersma

Publications and source records attributed to S Wiersma.

5 recordsLinked to original sources
PubMed2001

Marijuana use and social networks in a community outbreak of meningococcal disease.

BACKGROUND: We examined the role of social networks and marijuana smoking in a community outbreak of infections due to Neisseria meningitidis. METHODS: We interviewed all patients and their contacts. Isolates were tested by pulsed field electrophoresis and multilocus enzyme electrophoresis. RESULTS: Nine cases of meningococcal disease occurred in the outbreak; isolates from seven cases with positive cultures were identical. Multiple overlapping social networks were found for case-patients and their contacts. All case-patients were linked by the marijuana-related activities of their contacts. CONCLUSION: Investigation of social networks and marijuana exposure might help identify close contacts of patients with meningococcal disease and help prevent secondary infections.

Adolescent↗
PubMed1998

Pharmacokinetic and pharmacodynamic studies of fludarabine and cytosine arabinoside administered as loading boluses followed by continuous infusions after a phase I/II study in pediatric patients with relapsed leukemias. The Children's Cancer Group.

The sequential administration of fludarabine followed by cytosine arabinoside (ara-C) has demonstrated significant synergistic effects against the CEM human leukemic cell line. This in vitro synergism was investigated in a Phase I trial in pediatric patients with relapsed acute leukemia. The optimum concentrations of 9-beta-D-arabinofuranosyl 2-fluoroadenine and ara-C necessary to achieve significant drug synergism from in vitro studies were between 10 and 20 microM. Fludarabine was infused at a dose to attain a target plasma concentration of 10 microM for 48 h, followed by a continuous infusion of escalated ara-C doses to maintain plasma ara-C concentrations of 10, 12.5, 15, or 17.5 microM for 72 h. Thirteen patients with acute lymphocytic leukemia and 18 with acute myelocytic leukemia were entered into the study, 30 of whom were clinically evaluable for toxicity. Pharmacokinetic and pharmacodynamic studies were performed on specimens from 20 patients. The optimal 9-beta-D-arabinofuranosyl 2-fluoroadenine and ara-C concentrations in plasma were easily achieved after continuous infusion regimens of both drugs. Cellular ara-CTP is augmented 5-8-fold in leukemic cells from patients receiving fludarabine phosphate treatment followed by ara-C. The maximum tolerated plasma concentrations for this combination regimen was 10 microM fludarabine for 48 h followed by 72 h of 15 microM ara-C, which were achieved at dose level 3. A significant number of responses were also seen. Nine of 18 evaluable patients (50%) with acute myelocytic leukemia achieved complete or partial responses, and 3 of 9 evaluable patients with acute lymphocytic leukemia achieved complete or partial responses. Fludarabine and ara-C successfully eradicated bone marrow disease in 16 of 27 patients (59%), 23 patients of which had been treated previously with high-dose ara-C. These results verified the synergistic effect fludarabine exhibited in augmenting ara-CTP concentrations in patients' leukemic blasts, thus improving the clinical response in relapsed pediatric leukemias.

Adolescent↗
PubMed1997

Phase I/II study of idarubicin given with continuous infusion fludarabine followed by continuous infusion cytarabine in children with acute leukemia: a report from the Children's Cancer Group.

PURPOSE: The Children's Cancer Group (CCG) undertook a phase I study (CCG-0922) to determine a tolerable dose of idarubicin given with fludarabine and cytarabine in children with relapsed or refractory leukemia. The phase I study was extended to a limited phase II study to assess the activity of this combination in children with acute myelogenous leukemia (AML). PATIENTS AND METHODS: This was a multiinstitutional study within the CCG. Eleven patients were entered onto the phase I study: seven with AML, three with acute lymphoblastic leukemia (ALL), and one with chronic myelogenous leukemia (CML). The maximal-tolerated dose (MTD) of fludarabine and cytarabine determined in a previous study was a fludarabine loading dose (LD) of 10.5 mg/m2 followed by a continuous infusion (CI) of 30.5 mg/m2/24 hours for 48 hours, followed by cytarabine LD 390 mg/m2, then CI 101 mg/m2/h for 72 hours. Idarubicin was given at three dose levels: 6, 9, and 12 mg/m2 intravenously (I.V.) on days 0, 1, and 2. The phase II portion of the trial included 10 additional patients with relapsed or refractory AML. RESULTS: A dose of idarubicin 12 mg/m2/d for 3 days given in combination with fludarabine and cytarabine was tolerated. The major toxicity encountered was hematologic. Nonhematologic toxicities included transaminase elevations, hyperbilirubinemia, and infections. Eight of 10 patients with AML in the phase II portion (12 mg/m2 idarubicin) achieved a complete remission (CR). CONCLUSION: This combination is active in patients with relapsed or refractory AML. The major toxicity encountered is hematologic. This regimen may be useful therapy for AML and should be compared with standard induction therapy in children with newly diagnosed AML.

Acute Disease↗
PubMed1993

[Evaluation of the hepatitis B prevention program in newborn infants. II. Amsterdam, 1989-1991].

OBJECTIVE: To evaluate the efficiency of the hepatitis B surface antigen (HBsAg) screening programme in pregnant women and the hepatitis B prevention programme in neonates of HBsAg-positive mothers from October 1989 to December 1991. DESIGN: Retrospective. SETTING: Amsterdam Public Health Service, the Netherlands. METHOD: Analysis of the data routinely collected from pregnant women and neonates of these women and calculation of the protective efficiency of this immunisation programme. RESULTS: In 1990, 79% and in 1991, 91% of all pregnant women were screened for HBsAg. The overall prevalence was 1.2% in 1990 as in 1991. Of the HBsAg-positive women 96% originated from countries where hepatitis B virus (HBV) is known to be endemic. At the age of ten months all infants had received passive and active immunisation. The anti-HBs titre was 10-50 IU/l in 8 (7%) infants, > 50 IU/l in 94 (88%), 3 were HBsAg-negative with no information on the anti-HBs titre and in 2 HBsAg was present. The protective efficiency of the immunisation schedule was 94% in children born of e-antigen-positive and 93% in children born of e-antigen-negative mothers. CONCLUSION: Active surveillance and intense follow-up are essential in achieving high coverage rates in screening of pregnant women and in immunising neonates of HBsAg-positive mothers.

Adult↗