NEUDOSE: A CubeSat Mission for Dosimetry of Charged Particles and Neutrons in Low-Earth Orbit.

During space missions, astronauts are exposed to a stream of energetic and highly ionizing radiation particles that can suppress immune system function, increase cancer risks and even induce acute radiation syndrome if the exposure is large enough. As human exploration goals shift from missions in low-Earth orbit (LEO) to long-duration interplanetary missions, radiation protection remains one of the key technological issues that must be resolved. In this work, we introduce the NEUtron DOSimetry & Exploration (NEUDOSE) CubeSat mission, which will provide new measurements of dose and space radiation quality factors to improve the accuracy of cancer risk projections for current and future space missions. The primary objective of the NEUDOSE CubeSat is to map the in situ lineal energy spectra produced by charged particles and neutrons in LEO where most of the preparatory activities for future interplanetary missions are currently taking place. To perform these measurements, the NEUDOSE CubeSat is equipped with the Charged & Neutral Particle Tissue Equivalent Proportional Counter (CNP-TEPC), an advanced radiation monitoring instrument that uses active coincidence techniques to separate the interactions of charged particles and neutrons in real time. The NEUDOSE CubeSat, currently under development at McMaster University, provides a modern approach to test the CNP-TEPC instrument directly in the unique environment of outer space while simultaneously collecting new georeferenced lineal energy spectra of the radiation environment in LEO.

The effect of orchiectomy on lung cancer survival.

Gender is an independent prognostic factor for survival from lung cancer with the relative risk of lung cancer death for men compared to women being 1.3. This observation remains unexplained but in vitro data suggests a stimulatory effect of androgens on lung cancer growth. We hypothesized that androgen deprivation improves survival in men with lung cancer compared to hormonally intact men with lung cancer. On the basis of age, race and region, we matched 44 men with lung cancer and bilateral orchiectomy with 88 men who had lung cancer and no history of orchiectomy and compared their survival. Since hazards were non-proportional we chose the generalized gamma model to describe the survival function. The survival was significantly different between the two groups (p = 0.0048) with the orchiectomy group having a better two year overall survival. This retrospective study suggests that androgen depletion may significantly improve the short term survival of men with lung cancer but further, prospective investigation is required for confirmation.

Hematopoietic growth factors in the reduction of chemotherapeutic toxicity.

Neutropenia is the most common dose-limiting toxicity of conventional chemotherapy. The colony-stimulating factors (CSFs), granulocyte (G)-CSF and granulocyte-macrophage (GM)-CSF, stimulate proliferation and maturation of myeloid progenitors and have been effective in reducing neutropenia and its complications. The primary use of CSFs in patients receiving chemotherapy for small cell lung cancer has resulted in a reduction in the incidence of febrile neutropenia, a decrease in the duration of grade IV neutropenia, and a reduction in hospitalization time and antibiotic use. Although CSF use allows for higher dose intensity, a survival benefit has not been proven. The use of CSFs after the occurrence of neutropenic fever decreases the duration of grade IV neutropenia, but effects on hospitalization and antibiotic use are less well-defined. The therapeutic use of CSFs in the setting of established neutropenia, regardless of the presence or absence of fever, is not supported in the literature. The administration of CSFs to patients with acute myeloid leukemia is safe in that no trial has demonstrated evidence of leukemic stimulation with these drugs. As in other settings, the duration of neutropenia is shortened if CSFs are used postchemotherapy with evidence of clinical benefit. CSFs also decrease chemotherapeutic toxicity via other mechanisms. The use of G-CSF reduces the incidence of mucositis, in normal donors enhances the yield of leukapheresis for granulocyte transfusion, and is beneficial in the autologous transplant setting. These effects of CSFs in mitigating chemotherapeutic toxicity are reviewed.

Weight changes during pregnancy and the postpartum period.

Weight gain during pregnancy is considered a major determinant of fetal growth. Low maternal weight gain is associated with an increased incidence of low birth weight infants who are at higher risk for increased mortality. For the past twenty years, weight gain recommendations have been centered around one value (11 kg) as representative of a weight gain objective. Newer recommendations are based on what is considered optimal infant outcomes and not necessarily on maternal health considerations. These recent recommendations indicate the importance of pregravid weight in setting weight gain goals with overweight gravida advised to gain less than normal weight or underweight gravida. When confounding variables are controlled, maternal weight gain is similar in adolescents and older women. Reports on weight loss during the postpartum period indicate a high degree of variability in total weight change. In general, with current levels of weight gain, each successive birth adds about 1 kg of body weight above that normally gained with age. There is very little evidence to suggest that breast feeding as compared to other methods of infant feeding, causes body weight to return to prepregnancy levels at a faster rate.

Physicians' opinions and counseling practices in maternal and infant nutrition.

Opinions and practices regarding maternal and infant nutrition of general practitioners, pediatricians, and obstetricians in the province of British Columbia were surveyed by mail questionnaires. Scores were significantly higher for physicians who: (a) Were female; (b) consulted with a nutritionist-dietitian; (c) had additional training; (d) attended continuing education programs; and (e) had studied nutrition in their medical school curriculum. Pediatricians' and obstetricians' practice scores were significantly higher than those of general practitioners. However, there were no significant differences among the nutrition opinion scores for the three groups of physicians.