Galactic PeVatrons and helping to find them: Effects of galactic absorption on the observed spectra of very high energy γ-ray sources.

Identification of the cosmic-ray (CR) "PeVatrons," which are sources capable of accelerating particles to ~1015 eV energies and higher, may lead to resolving the long-standing question of the origin of the spectral feature in the all-particle CR spectrum known as the "knee." Because CRs with these energies are deflected by interstellar magnetic fields identification of individual sources and determination of their spectral characteristics is more likely via very high energy γ-ray emissions, which provide the necessary directional information. However, pair production on the interstellar radiation field (ISRF) and cosmic microwave background (CMB) leads to steepening of the high energy tails of γ-ray spectra, and should be corrected for to enable true properties of the spectrum at the source to be recovered. Employing recently developed three-dimensional ISRF models this paper quantifies the pair-absorption effect on spectra for sources in the Galactic center (GC) direction at 8.5 and 23.5 kpc distances, with the latter corresponding to the far side of the Galactic stellar disc where it is expected that discrimination of spectral features >10 TeV is possible by the forthcoming Cherenkov Telescope Array (CTA). The estimates made suggest spectral cutoffs could be underestimated by factors of a few in the energy range so far sampled by TeV γ-ray telescopes. As an example to illustrate this, the recent HESS measurements of diffuse γ-ray emissions possibly associated with injection of CRs nearby Sgr A* are ISRF corrected, and estimates of the spectral cutoff are reevaluated. It is found that it could be higher by up to a factor of ~2, indicating that these emissions may be consistent with a CR accelerator with a spectral cutoff of at least 1 PeV at the 95% confidence level.

Improved outcomes of children with malignancy admitted to a pediatric intensive care unit.

OBJECTIVE: To assess the acute and long-term outcomes of children admitted to the intensive care unit with cancer or complications after bone marrow transplantation. DESIGN: Retrospective analysis of databases from a prospective pediatric intensive care unit (PICU) database supplemented by case notes review. SETTING: A PICU in a tertiary pediatric hospital. PATIENTS: All children with malignancy admitted to the PICU between May 1, 1987, and April 30, 1996. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 206 admissions to the PICU during a 9-yr study period of 150 children with malignancies or complications after bone marrow transplantation. Forty patents died in the PICU (27% mortality rate). The most frequent indications for PICU admission were shock and respiratory disease. Of 56 children admitted with shock, there were 16 deaths (29% mortality rate). In 24 episodes of sepsis, inotropic and ventilatory support were required and 13 patients (54%) survived. Analysis of long-term survival gave estimates of 50% survival for all oncology patients admitted to the PICU and 42% for those admitted for shock. CONCLUSIONS: A high proportion of oncology patients admitted to the PICU requiring intensive intervention survive and go on to be cured of their malignancy. Our study suggests the PICU outcome for these patients has improved.

Childhood acute myeloid leukemia: outcome in a single center using chemotherapy and consolidation with busulfan/cyclophosphamide for bone marrow transplantation.

PURPOSE: To report the impact of bone marrow transplantation (BMT) with busulfan/cyclophosphamide (BuCy) as end consolidation in a cohort of consecutively diagnosed children with acute myeloid leukemia (AML). PATIENTS AND METHODS: Between May 1987 and November 1992, 43 patients were diagnosed with AML. Tissue typing at diagnosis determined whether patients would proceed to autologous or allogeneic BMT as end consolidation after six cycles of chemotherapy. Conditioning for BMT was with BuCy, followed by allogeneic or unpurged autologous marrow infusion. RESULTS: Of 37 patients who received chemotherapy, 35 achieved remission (95%) after one to six courses of treatment and 34 (92%) were transplanted. Five relapsed before BMT, four were subsequently transplanted in second complete remission (CR2) (n = 3) or untreated first relapse (n = 1), and one failed to respond to further therapy. All other patients proceeded to BMT in first complete remission (CR1). Eleven patients received allografts: one relapsed and one died of graft-versus-host disease (GvHD), for a leukemia-free survival rate of 90% at a median of 41 months after BMT (range, 3 to 60). For 23 autografts, there were two toxic deaths and eight relapses, with a leukemia-free survival rate of 61% at a median of 11 months after BMT (range, 0 to 66). The high relapse rate following autologous BMT led us to escalate the dose of Bu from 16 mg/kg to 600 mg/m2 using a single daily dose of Bu. CONCLUSION: With modern supportive therapy, most newly diagnosed children with AML will enter remission and are eligible for intensification therapy. BuCy is well tolerated in children, which allowed us to escalate the dose of Bu in recent patients. Further follow-up is needed to determine whether this has an impact on the relapse rate following autologous BMT.

Beta-endorphin in pituitary intraglandular colloid of intermediate lobe origin.

Radioimmunoassay (RIA) detected the presence of beta-endorphin in the intraglandular colloid (IGC) of bovine pituitary intermediate lobe origin. The amount of beta-endorphin recovered in each of twelve samples ranged from 0.15 to 218.30 pmol/mg protein. A second group of assays [amino acid analysis, high performance liquid chromatography (HPLC) and mass spectral analysis] confirmed the RIA findings in another series of colloid samples. Approximately 75 pmol was collected from eight pooled glands. beta-Endorphin is an addition to the list of peptide hormones (e.g., methionine-enkephalin, adrenocorticotropin, arginine-vasopressin, alpha-melanocyte-stimulating hormone, beta-lipotropin and somatostatin) previously discovered in IGC by this laboratory.