Random control clinical trial on the effects of aerobic exercise training on erythrocyte levels during radiation treatment for breast cancer

BACKGROUND: Erythrocyte changes from aerobic exercise training were examined during radiation treatment of breast cancer. METHODS: Twenty sedentary females with breast carcinoma who were ages 35 to 65 years were randomized to aerobic exercise (AE) of walking for 20 to 45 minutes, 3 to 5 times per week, at 50% to 70% of measured maximum heart rates or to placebo stretching (PS) activities 3 to 5 days per week during 7 weeks of radiation treatment. Measures were obtained 1 week before and after the radiation regimen. Serum blood analyses, through complete blood counts, measured red blood cell counts (RBC), hematocrit (HCT), and hemoglobin (HB). Peak aerobic capacity (peak VO(2)) was measured by exercise testing with oxygen uptake analysis to assess training. A Wilcoxon Mann-Whitney U test examined changes between groups (P < or = .05 for significance). RESULTS: AE peak VO(2) increased by 6.3% (P = .001) and PS decreased by 4.6% (P = .083). RBC increased in AE from 4.10 to 4.21 million cells/microL and declined in PS from 4.30 to 4.19 million cells/microL; the between-group differences were significant (P = .014). HCT increased in AE from 38.0% to 38.8% and declined in PS from 37.40% to 36.50%; the between-group differences were significant (P = .046). HB increased in AE from 12.3 to 12.4 g/dL and declined in PS from 12.25 to 11.77 g/dL; the between-group differences were significant (P = .009). CONCLUSIONS: The results of the current study suggest that moderate intensity aerobic exercise appears to maintain erythrocyte levels during radiation treatment of breast cancer compared with the declines observed in nontraining individuals. These findings suggest a safe, economical method to improve fitness and maintain erythrocytes in women during radiation treatment of breast cancer.     

Medical students as teachers and role models for their future colleagues

Medical schools seldom involve students in applicant recruitment. The authors describe the role of junior medical students in recruitment at the University of Ottawa, aiming to increase the Franco-Ontarian applicant pool for the French-language medical program. The students have designed workshops reflecting their study program and offered them, since 1997, to 719 Ontario French-language high school students and to 291 francophone undergraduate university students. The workshops emphasize role modeling by medical students who act as physician-teachers while attendees act as medical students. Evaluation measures include attendee surveys, medical student focus groups and faculty admissions statistics. Attendees give uniformly positive evaluations, highlighting the importance of role modeling. Medical students find teaching enjoyable and highly educational. Admissions statistics show that the Franco-Ontarian applicant pool has more than doubled in spite of an almost fourfold increase in tuition fees. This experience has shown that junior medical student involvement in recruitment activities can benefit both the trainees and their institution.     

Variations in blood viscosity of insulin-dependent diabetic subjects controlled by artificial pancreas (author's transl)

A study of blood viscosity at 3 rates of determination (0.232-0.348 and 1.16 sec-1) in insulin-dependent diabetic subjects controlled by artificial pancreas, shows a reduction in this parameter after 30 hours of feed back control. The relationship between these variations, the mechanical cohesion of the agglutinated red cells, and the deformability of these structures are discussed.     

Early after/depolarizations and triggered activity: mechanisms and autonomic regulation

Summary— An early after/depolarization (EAD) is an abnormality of the repolarization process of an action potential which causes an interruption or a retardation of normal repolarization. Two types were described: phase 3 EADs occur at a takeoff potential of approximately − 60 mV and phase 2 EADs occur at the end of a prolonged plateau at a takeoff potential of between − 10 and − 30 mV. EADs can result from an increase in inward current, a reduction of outward current or both. EADs show cycle-length dependence: as cycle length increases and repolarization lengthens, EADs occur, and their magnitude increases, at a critical cycle length, can trigger the action potential of these EADs. The autonomic nervous system can also modulate EADs and trigger activity. In cesium-intoxicated Purkinje fibers, beta-adrenergic stimulation increases EAD magnitude and the occurrence of triggered activity. Cholinergic stimulation decreases EAD magnitude and suppresses triggered activity occurring after beta-adrenergic stimulation. Alpha 1-adrenergic stimulation has no effect on phase 3 EADs but induces phase 2 EADs. In normal Tyrode's solution (0 cesium), phenylephrine prolongs action potential and induces EADs. This effect seems to depend on alpha 1 A stimulation. These electrogenic abnormalities are supposed to be responsible for long QT and torsades de pointes. As our experimental data have shown that both the rate of stimulation and the autonomic nervous system could modulate EADs and trigger activity, we can speculate on the therapeutic implications of such modulations and the role of pacing as well as alpha- and beta-adrenergic antagonists.     

Increased frequency of multiradial chromosome structures in mouse embryonic fibroblasts lacking functional Werner syndrome protein and poly(ADP-ribose) polymerase-1

To determine whether the mouse Werner syndrome homologue (Wrn) and the poly (ADP-ribose) polymerase-1 (PARP-1) enzymes act in concert to prevent specific chromosomal rearrangements, mice with a mutation in the helicase domain of the Wrn gene (Wrn(Deltahel/Deltahel) mice) were crossed to PARP-1 null mice. Spectral karyotyping of the mouse metaphases was used in correlation with conventional G-banded karyotype analysis to precisely define the chromosomal aberrations in cells. Although there was no recurrent clonal chromosome aberration, PARP-1 null/Wrn(Deltahel/Deltahel) fibroblasts were distinguished by an increased frequency of chromatid breaks. Interestingly, multiradial structures were the only type of DNA rearrangement that was significantly higher in such PARP-1 null/Wrn(Deltahel/Deltahel) cells. These results indicate that Wrn and PARP-1 enzymes may be part of a protein complex involved in the processing of DNA breaks that can ultimately lead to multiradial structures when both enzymes are nonfunctional. Finally, regions of chromosomes known to be fragile sites in the mouse genome are not more prone to DNA rearrangements in the absence of both PARP-1 and functional Wrn proteins. Moreover, the low number of recurrent rearranged chromosome at any given site suggest a random mutagenesis process in PARP-1 null/Wrn(Deltahel/Deltahel) fibroblasts.     

New prototype neuronavigation system based on preoperative imaging and intraoperative freehand ultrasound: system description and validation

Purpose  

The aim of this report is to present IBIS (Interactive Brain Imaging System) NeuroNav, a new prototype neuronavigation system that has been developed in our research laboratory over the past decade that uses tracked intraoperative ultrasound to address surgical navigation issues related to brain shift. The unique feature of the system is its ability, when needed, to improve the initial patient-to-preoperative image alignment based on the intraoperative ultrasound data. Parts of IBIS Neuronav source code are now publicly available on-line.