[Childhood and adult medulloblastoma: what difference?]

Medulloblastoma is the most frequent childhood brain tumor (30%) but account only for less than 1% of adult brain tumor. The overall survival increased significantly during the last two decades with 80% of long survivors at five years whatever the stage. Most children who survive have significant neurocognitive sequelae. All children are included in national and international prospective studies which propose risk-adapted radiation therapy and chemotherapy after surgery. Quality control of radiotherapy leads to reduce significantly the risk of recurrence and has an impact on survival. Risks of late toxicity should be taken into account at the time of the treatment. Due to the rarety in adult population, no prospective studies and few data about late effects are available. Adult medulloblastoma is a therapeutic challenge and their therapeutic strategies are similar to pediatric protocols. In order to improve the understanding of adult disease and to homogenize the treatment, National Cancer Institute (INCa) stimulated the creation of web conference to discuss each case prospectively and to propose a protocol of treatment. A better comprehension of biological processes and abnormal cellular signalling pathways involved in medulloblastoma pathogenesis had led toward a new prognostic classification to adapt the therapeutic strategy and gives hope of new therapeutic tools.

[Metronomic chemotherapy in pediatric oncology: hype or hope?]

Angiogenesis is crucial for the growth of cancer. As such, it has become an established target in fighting cancer. Metronomic chemotherapy-the chronic administration of chemotherapy at relatively low, minimally toxic doses on a frequent schedule of administration at close regular intervals, with no prolonged drug-free breaks-is a potential novel approach to controlling advanced cancer disease. It is thought to work primarily through antiangiogenic mechanisms and has the property of killing resistant cancer cells while significantly reducing undesirable toxic side effects. We review the data regarding the use of metronomic chemotherapy in children with cancer and discuss its potential uses and limits.

Tethys and Dione as sources of outward-flowing plasma in Saturn’s magnetosphere

Rotating at over twice the angular speed of Earth, Saturn imposes a rapid spin on its magnetosphere. As a result, cold, dense plasma is believed to be flung outward from the inner magnetosphere by centrifugal force and replaced by hotter, more tenuous plasma from the outer magnetosphere. The centrifugal interchange of plasmas in rotating magnetospheres was predicted many years ago and was conclusively demonstrated by observations in Jupiter's magnetosphere, which--like that of Saturn (but unlike that of Earth)--is rotationally dominated. Recent observations in Saturn's magnetosphere have revealed narrow injections of hot, tenuous plasma believed to be the inward-moving portion of the centrifugal interchange cycle. Here we report observations of the distribution of the angle between the electron velocity vector and the magnetic field vector ('pitch angle') obtained in the cold, dense plasma adjacent to these inward injection regions. The observed pitch-angle distributions are indicative of outward plasma flow and consistent with centrifugal interchange in Saturn's magnetosphere. Further, we conclude that the observed double-peaked ('butterfly') pitch-angle distributions result from the transport of plasma from regions near the orbits of Dione and Tethys, supporting the idea of distinct plasma tori associated with these moons.

Lack of interaction between etifoxine and CRF1 and CRF2 receptors in rodents

Hyperactivity of the corticotropin-releasing factor (CRF) system occurs in some patients with anxiety disorders and depression. Blockade of CRF1 and CRF2 receptors can underlie the anxiolytic effects of drugs. In the present investigation, in vivo and in vitro studies were designed to determine whether the anxiolytic drug etifoxine, known to enhance GABAergic synaptic transmission, behaves also as a CRF1 and CRF2 receptor antagonist. A drug exerting multiple actions may be of clinical interest in the treatment of various different forms of mood disorders. Using two animal models, it was found that etifoxine reversed the excess CRF-induced grooming but not the hypo-locomotion of the rat placed in an open field. Etifoxine attenuated the CRF-induced gastric emptying delay in the mouse. On the other hand, in vitro, binding of etifoxine to CRF1 and CRF2 receptors on rat brain membranes was negligible and functionally, etifoxine did not block the CRF1 and CRF2 activation-induced cAMP production in presence of CRF in human neuroblastoma SH-SY5Y cells. The selective anxiolytic properties of etifoxine appear unrelated to an antagonist activity at the CRF1 and CRF2 receptors. The decrease in CRF activity produced by etifoxine may be related to its GABAergic properties.

[Antimitochondrial agents: a new class of anticancer agents]

Over the last 2 decades, the role of apoptosis in anticancer agent cytotoxicity has become clear. Defects in the regulation of apoptosis (programmed cell death) make important contributions to the pathogenesis and progression of most cancers and leukemias. Apoptosis defects also have a key role in cell resistance to chemotherapy. Mitochondria play a central part in cell death in response to anticancer agents. Most of these agents target mitochondria via caspases or other regulator elements of the apoptotic machinery. Nevertheless, some anticancer agents, already in clinical use (paclitaxel, vinblastine, lonidamine, etoposide, arsenic trioxide) or in pre-clinical development (betulinic acid, MT21), directly target and permeabilize mitochondria. The acknowledgement of mitochondria as a new target for anticancer agents provides a new way to bypass cancer cell chemoresistance.

[Infectious complications postengrafment in the first year after autologous stem cell transplantation in children]

BACKGROUND

Studies on the infectious complications postengrafment in pediatric stem cell transplantation patients are rare. The aim of this study was to assess the incidence, types, outcome and factors affecting late infections.

PATIENTS AND METHODS

A single-institution retrospective analysis was done of infections recorded in the first year following engrafment in children who underwent autologous stem cell transplantation for solid tumors from January 1991 to December 2000. A systematic antimicrobial chemoprophylaxis of TMP/SMX was administered. Patients who were at high risk for varicella-zona virus infection received prophylactic acyclovir.

RESULTS

Eighty-four assessable patients were enrolled. Fifty-four patients (64%) underwent autologous peripheral blood stem cell transplantation and 30 patients (36%) underwent bone marrow transplantation. Forty-nine episodes of infections were documented in 39 patients (46%) of whom 27 patients (32%) developed infections after the first 100 days post transplantation. Bacterial septicemia occurred in nine patients of whom four patients had a catheter-related septicemia. Twelve patients (14%) developed localized herpes zoster infection. Local fungal infection occurred in five patients. Infection-related death occurred in one patient with non-documented pneumonitis. Univariable analysis showed a correlation between the CD34(+) cell dose <7.5 10(6)/kg and the development of infections (P =0.04). Patients who did not go into remission after transplantation where at high risk for septicemia (P =0.007). Multivariate analysis showed that a history of varicella or pretransplant varicella-zona positivity was the only significant factor for development zoster infection (P =0.01).

CONCLUSION

Our study shows that infections in the first year postengrafment following autologous stem cell transplantation for solid tumors have a good prognosis and that the use of TMP/SMX should be the single systematic antimicrobial prophylaxis. The CD34(+) cell dose seems to play a role in preventing late infections.