The use of MRI to guide and monitor interventional procedures requires the merging of surgical and MRI environments. The ideal magnet shape for homogeneity and efficiency is spherical, but this design provides no access. Opening the sphere to provide both patient and surgeon access suggests cylindrical or biplanar magnets. Cylindrical magnets have poor surgical access but provide good imaging capabilities, which can be used in conjunction with a neighboring but distinct surgical environment. Biplanar magnets provide more and better approaches to the patient, but generally with lower field strength. Vertical biplanar systems allows surgical approaches from above but reduce the access of support staff to the patient. A hybrid magnet design, which combines the benefits of both cylindrical and biplanar magnets, can provide increased access with simultaneous approach from two sides of the patient. Application-specific magnets can target a smaller region, leading to compact magnet designs that greatly expand access for both surgical intervention as well as patient support. As the field of interventional MRI matures, the suitability of each design to specific applications will be better understood, leading to more integrated system designs tailored to the needs of image-guided therapy.

Equipment Design↗

PubMedDate not supplied

Community-based surveillance of cardiovascular risk factors in Geneva: methods, resulting distributions, and comparisons with other populations.

OBJECTIVES: This paper presents the results of an ongoing community-based surveillance program of cardiovascular risk factors in Geneva, Switzerland, using percentiles with their associated 95% confidence intervals and compares the Genevan results with published data from international surveys reporting percentiles. METHODS: A random survey of adults ages 35 to 74 years was conducted from 1993 to 1994. Confidence intervals for percentiles based on parametric and non-parametric methods are given. RESULTS: The distribution of total cholesterol was shifted upward with increasing age. The median reached a maximum at 55-64 years among men (5.7 mmol/L) and at 65-74 years among women (5.9 mmol/L), and remained relatively stable thereafter. In both genders, systolic and, less so, diastolic blood pressure increased progressively with advancing age. The median daily energy intake among men declined from 2,390 kcal at age 35-44 years to 2,169 kcal at age 65-74 years, while among women it remained stable at about 1,900 kcal. In both males and females, the relative intake of saturated fat was stable throughout life (14 to 13%). The median body mass index (BMI) was about 25 kg/m2 across all age groups among men, but increased with age among women, with a peak of 23.6 kg/m2 occurring at ages 65-74 years. Compared with U.S. and western European surveys, Genevan men and women had lower total plasma cholesterol and Genevan women tended to have lower BMIs. CONCLUSIONS: Percentiles with their associated precision appear particularly well suited for international comparison of surveillance data. They could be used in the future to monitor shifts in distributions resulting from mass prevention strategies.

Adult↗

PubMedDate not supplied

Smoking behavior in a Swiss urban population: the role of gender and education.

BACKGROUND: Smoking has become more prevalent among U.S. men and women and European men in lower socioeducational groups. The relation between socioeducational status and smoking among European women has been studied less. METHODS: A survey assessing the smoking behavior and educational level of 943 women and 961 men ages 35 to 74 years from Geneva, Switzerland, was conducted. RESULTS: The prevalence of never smokers has declined among younger women but has remained stable among men. More men than women have ever smoked, but the difference has decreased among younger generations. Ever smoking was more prevalent among women with secondary (47.6%, age-adjusted OR 2.03, 95% CI 1.29 to 3.18) or tertiary (46.6%, age-adjusted OR 1.83, 95% CI 1.13 to 2.97) education relative to women with primary education (30.7%). Among males, ever smoking was slightly more prevalent among lower levels of education. There were moderate differences in quit ratio (ex-smokers/ever smokers) across educational levels among women (trend P = 0.08). In contrast, men with tertiary education stopped smoking more often (63.6%) than those with secondary (54.2%) or primary (47.6%) education (trend P = 0.008). For most women, primary education was associated with a later age at start of smoking while the inverse was true for men. CONCLUSION: Smoking behavior is evolving across generations of women in Geneva. It is more prevalent among educated women of the older generations, but this is less so among the younger generations. Women from Geneva may be currently experiencing the transition of smoking from upper to lower social classes.

Adult↗

PubMedDate not supplied

Radiosensitization of the RIF-1 murine flank tumor by desmethylmisonidazole (Ro 05 9963) during interstitial brachytherapy.

We have investigated the interaction of the nitroimidazole radiosensitizer desmethylmisonidazole (Ro 05 9963) with interstitial radiation using a clonogenic cell assay as the endpoint. Removable I-125 sources were implanted at right angles to the outer surface of globular RIF-1 tumors grown in the flanks of C3H/He mice. Desmethylmisonidazole was administered by continuous intraperitoneal infusion at a rate of 2.7 mg/gm body weight /24 hr. Tumor and serum drug levels were measured by high performance liquid chromatography. Tumor drug levels of 40--100 mugm/gm tumor tissue were achieved consistently. No appreciable cytotoxicity was produced by desmethylmisonidazole alone, but a radiosensitization effect with a dose modifying factor of 1.6 was found.

Animals↗

PubMedDate not supplied

A population-based study of the usefulness of screening for neuroblastoma.

BACKGROUND: Neuroblastoma has many characteristics which suggest that preclinical detection might improve outcome. The Quebec Neuroblastoma Screening Project was initiated to determine whether mass screening could reduce mortality in a large cohort of infants. As an early endpoint, we report whether screening could reduce the incidence of poor-prognosis neuroblastoma in children with advanced-stage disease over 1 year of age. METHODS: All 476,603 children born in the province of Quebec during the 5-year period of May 1, 1989, to April 30, 1994, were eligible for urinary assay of homovanillic acid and vanillylmandelic acid at 3 weeks and 6 months of age. Children with a positive screen were referred to one of four paediatric cancer centres in the province for uniform evaluation and treatment if necessary. Standardised incidence ratios (SIRs) were calculated for neuroblastoma in the province and two similar population-based controls, the state of Minnesota and the province of Ontario, during the same period of time and with similar ascertainment procedures. FINDINGS: Compliance with screening in Quebec province was 91% at 3 weeks (n = 425,816) and 74% at 6 months (n = 349,706). Through July 31, 1995, with a follow-up of the birth cohort of 15-75 months, 118 cases of neuroblastoma were diagnosed, 43 detected preclinically by screening, 20 detected clinically before screening at 3 weeks of age, and 55 detected clinically after 3 weeks of age having normal screens (52) or never screened (3). Retrospective analysis of stored samples confirmed that 49 of 52 patients missed by screening had levels of catecholamine metabolites that were too low to be detected at 6 months or earlier. Based on US Surveillance, Epidemiology and End Results data, 54.5 cases of neuroblastoma would have been expected in Quebec province during the study period, for an SIR of 2.17 (95% CI 1.79-2.57, p < 0.0001). For the two control groups, 43 and 80 cases of neuroblastoma were detected, respectively, compared with 37.9 and 85.4 expected, overall SIR 1.00 (not significant). SIRs for Quebec province by age at diagnosis in yearly intervals show a marked increased incidence under 1 year of age (SIR 2.85, 2.26-3.50), with no reduction in incidence in subsequent years. Limiting analysis to only patients diagnosed over 1 year of age with advanced-stage disease, 22 cases were detected in Quebec province versus 14.4 expected (SIR 1.52, 0.95-2.23). Data in the two control groups show no significant increase or decrease in any-stage disease in children under or over the age of 1 year, except for an increase in early-stage disease in Minnesota children over 1 year: 10 versus 3.8 expected (SIR 2.67, 1.27-4.58). INTERPRETATION: Screening for neuroblastoma increases the incidence in infants without decreasing the incidence of unfavourable advanced-stage disease in older children. It is unlikely that screening for neuroblastoma in infants will reduce mortality for this disease.

Chromatography, Thin Layer↗

PubMedDate not supplied

Estrogen modulation: tiered testing for human hazard evaluation. American Industrial Health Council, Reproductive and Developmental Effects Subcommittee.

Recent concerns about the potential of certain chemicals to modulate estrogen-regulated processes have led to questions as to how chemicals should be tested for such effects. Therefore, AIHC has developed a comprehensive, resource-efficient, and flexible tiered strategy for estrogen modulation (EM) testing. Levels of evaluation include Tier 0, in which exposure, along with alerts based on structure-activity, persistence, bioaccumulation, and other data, are assessed to prioritize chemicals for preliminary testing. In Tier I, short term in vitro, ex vivo, and/or in vivo assays are used to obtain a preliminary indication of EM potential. Among these, an in vivo response assay is considered the most reliable at this time. However, none of these tests are intended for risk assessment, but rather to aid in choosing chemicals for further testing and in guiding the extent of that testing. Tier II is aimed at risk assessment and involves whole animal tests that contain EM-sensitive end points (e.g., two-generation reproduction study). Tier III consists of hypothesis-driven research reserved for situations where targeted research can reduce levels of uncertainty. This tiered approach provides a framework for the strategic and effective application of EM test methods to address specific information needs on a case by case basis.

Animals↗

PubMedDate not supplied

A functional hypothesis for LGN-V1-TRN connectivities suggested by computer simulation.

We employ computer simulation to investigate the function of neural circuitries between thalamic sensory relay nuclei, primary sensory cortices, and the thalamic reticular nucleus (TRN). Computational similarities exist between these circuits and the architecture of a simple artificial neural network. We impose processing parameters on this network architecture in keeping with anatomical and physiological details of the mammalian geniculo-cortical visual pathway, and then run the simulation on a task involving multiple simultaneous inputs from the simulated visual field. After two to three loops through the simulation, activity in cortical and thalamic units whose receptive fields include the stronger stimulus remains constant, while activity in other cortical and thalamic units activated by weaker stimuli declines toward resting values. These results suggest that the modeled neural circuitry functions to "prime" selective attentional mechanisms further up the visual streams toward specific portions of the total visual stimulus. Besides extending existing models and evidence about the function of these neural circuits, our results also provide physiologists with predicted activity profiles of thalamic and cortical elements of the modeled neural system for a task not yet studied experimentally.

Animals↗

PubMedDate not supplied

Topotecan in pediatric patients with recurrent and progressive solid tumors: a Pediatric Oncology Group phase II study.

PURPOSE: A phase II study was designed to determine the efficacy of topotecan, an inhibitor of topoisomerase I, in the treatment of patients with progressive or recurrent pediatric extracranial solid tumors (STs). PATIENTS AND METHODS: Patients younger than 21 years at the time of initial diagnosis with refractory STs were treated with 2 mg/m2 topotecan given by 30-minute infusions for 5 days repeated every 3 weeks. Granulocyte colony stimulating factor (G-CSF) was added to the regimen only after occurrence of severe neutropenia or therapy delay due to sustained neutropenia. RESULTS: One hundred forty-one patients were treated with 539 courses of topotecan. Responses were seen in 34 patients (3 had complete responses [CRs], 2 had partial responses [PRs], and 24 had minor responses [MRs] or stable disease [SD]). The number of administered courses in patients with SD varied between 5 and 24, with a median of 10. The median time on the study for patients with SD was approximately 8.5 months. In patients without bone marrow involvement, the most frequent toxicity was myelosuppression: hemoglobin < 8 g/dl in 83 of 341 courses, absolute granulocyte count < 1,000/microl in 221 of 341 courses, and platelet count < 50,000/microl in 162 of 341 courses. Nausea and vomiting were infrequent; many patients were pretreated with ondansetron or granisetron. A recurrent rash developed in 16 patients and was usually well controlled with diphenhydramine and hydrocortisone. G-CSF was administered in 203 of 539 courses because of neutropenia. Therapy was delayed over 1 week in 33 instances. CONCLUSION: In previously treated patients, topotecan produced CRs and PRs in patients with neuroblastoma, Ewing's tumor, and retinoblastoma. In hepatoblastoma, rhabdomyosarcoma, and a few rare tumors, long-lasting MRs and SDs with excellent symptom control were seen. The toxicity of topotecan, predominantly myelosuppression, was tolerable.

Adolescent↗