OBJECTIVE: To examine the relationship between different Internet-use intensities and adolescent mental and somatic health. METHODS: Data were drawn from the 2002 Swiss Multicenter Adolescent Survey on Health, a nationally representative survey of adolescents aged 16 to 20 years in post-mandatory school. From a self-administered anonymous questionnaire, 3906 adolescent boys and 3305 girls were categorized into 4 groups according to their intensity of Internet use: heavy Internet users (HIUs; >2 hours/day), regular Internet users (RIUs; several days per week and ≤2 hours/day), occasional users (≤1 hour/week), and non-Internet users (NIUs; no use in the previous month). Health factors examined were perceived health, depression, overweight, headaches and back pain, and insufficient sleep. RESULTS: In controlled multivariate analysis, using RIUs as a reference, HIUs of both genders were more likely to report higher depressive scores, whereas only male users were found at increased risk of overweight and female users at increased risk of insufficient sleep. Male NIUs and female NIUs and occasional users also were found at increased risk of higher depressive scores. Back-pain complaints were found predominantly among male NIUs. CONCLUSIONS: Our study provides evidence of a U-shaped relationship between intensity of Internet use and poorer mental health of adolescents. In addition, HIUs were confirmed at increased risk for somatic health problems. Thus, health professionals should be on the alert when caring for adolescents who report either heavy Internet use or very little/none. Also, they should consider regular Internet use as a normative behavior without major health consequence.

Dosimetry studies in patients with non-Hodgkin's lymphoma were performed to estimate the radiation absorbed dose to normal organs and bone marrow from 90Y-Zevalin (yttrium-90 ibritumomab tiuxetan, IDEC-Y2B8) treatment in this phase I/II, multicenter trial. The trial was designed to determine the dose of Rituximab (chimeric anti-CD20, Rituxan, IDEC-C2B8, MabThera), the unlabeled antibody given prior to the radioconjugate to clear peripheral blood B cells and optimize distribution, and to determine the maximum tolerated dose of 90Y-Zevalin [7.4, 11, or 15 MBq/kg (0.2, 0.3, or 0.4 mCi/kg)]. Patients received (111)In-Zevalin (indium-111 ibritumomab tiuxetan, IDEC-In2B8 ) on day 0 followed by a therapeutic dose of 90Y-Zevalin on day 7. Both doses were preceded by an infusion of the chimeric, unlabeled antibody Rituximab. Following administration of (111)In-Zevalin, serial anterior/posterior whole-body scans were acquired. Major-organ radioactivity versus time estimates were calculated using regions of interest. Residence times were computed and entered into the MIRDOSE3 computer software program to calculate estimated radiation absorbed dose to each organ. Initial analyses of estimated radiation absorbed dose were completed at the clinical site. An additional, centralized dosimetry analysis was performed subsequently to provide a consistent analysis of data collected from the seven clinical sites. In all patients with dosimetry data (n=56), normal organ and red marrow radiation absorbed doses were estimated to be well under the protocol-defined upper limit of 20 Gy and 3 Gy, respectively. Median estimated radiation absorbed dose was 3.4 Gy to liver (range 1.2-7.8 Gy), 2.6 Gy to lungs (range 0.72-4.4 Gy), and 0.38 Gy to kidneys (range 0.07-0.61 Gy). Median estimated tumor radiation absorbed dose was 17 Gy (range 5.8-67 Gy). No correlation was noted between hematologic toxicity and the following variables: red marrow radiation absorbed dose, blood T(1/2), blood AUC, plasma T(1/2), and plasma AUC. It is concluded that 90Y-Zevalin administered at nonmyeloablative maximum tolerated doses results in acceptable radiation absorbed doses to normal organs. The only toxicity of note is hematologic and is not correlated to red marrow radiation absorbed dose estimates or T(1/2), reflecting that hematologic toxicity is dependent on bone marrow reserve in this heavily pretreated population.

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