The gravity field of a small body provides insight into its internal mass distribution. We used two approaches to measure the gravity field of the rubble-pile asteroid (101955) Bennu: (i) tracking and modeling the spacecraft in orbit about the asteroid and (ii) tracking and modeling pebble-sized particles naturally ejected from Bennu's surface into sustained orbits. These approaches yield statistically consistent results up to degree and order 3, with the particle-based field being statistically significant up to degree and order 9. Comparisons with a constant-density shape model show that Bennu has a heterogeneous mass distribution. These deviations can be modeled with lower densities at Bennu's equatorial bulge and center. The lower-density equator is consistent with recent migration and redistribution of material. The lower-density center is consistent with a past period of rapid rotation, either from a previous Yarkovsky-O'Keefe-Radzievskii-Paddack cycle or arising during Bennu's accretion following the disruption of its parent body.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The top-shaped morphology characteristic of asteroid (101955) Bennu, often found among fast-spinning asteroids and binary asteroid primaries, may have contributed substantially to binary asteroid formation. Yet a detailed geophysical analysis of this morphology for a fast-spinning asteroid has not been possible prior to the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Combining the measured Bennu mass and shape obtained during the Preliminary Survey phase of the OSIRIS-REx mission, we find a notable transition in Bennu’s surface slopes within its rotational Roche lobe, defined as the region where material is energetically trapped to the surface. As the intersection of the rotational Roche lobe with Bennu’s surface has been most recently migrating towards its equator (given Bennu’s increasing spin rate), we infer that Bennu’s surface slopes have been changing across its surface within the last million years. We also find evidence for substantial density heterogeneity within this body, suggesting that its interior is a mixture of voids and boulders. The presence of such heterogeneity and Bennu’s top shape are consistent with spin-induced failure at some point in its past, although the manner of its failure cannot yet be determined. Future measurements by the OSIRIS-REx spacecraft will provide insight into and may resolve questions regarding the formation and evolution of Bennu’s top-shape morphology and its link to the formation of binary asteroids.

Scheeres, D. J.; McMahon, J. W.; French, A. S.; Brack, D. N.; Chesley, S. R.; Farnocchia, D.; Takahashi, Y.; Leonard, J. M.; Geeraert, J.; Page, B.; Antreasian, P.; Getzandanner, K.; Rowlands, D.; Mazarico, E. M.; Small, J.; Highsmith, D. E.; Moreau, M.; Emery, J. P.; Rozitis, Benjamin; Hirabayashi, M.; Sánchez, P.; Van wal, S.; Tricarico, P.; Ballouz, R.-L.; Johnson, C. L.; Al Asad, M. M.; Susorney, H. C. M.; Barnouin, O. S.; Daly, M. G.; Seabrook, J. A.; Gaskell, R. W.; Palmer, E. E.; Weirich, J. R.; Walsh, K. J.; Jawin, E. R.; Bierhaus, E. B.; Michel, P.; Bottke, W. F.; Nolan, M. C.; Connolly, H. C. and Lauretta, D. S. (2019). The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements. Nature Astronomy, 3 pp. 352–361.

Exertional leg pain often has no definitive diagnosis in athletes. Little research has been done regarding exertional calf pain. The majority of reports are of exertional shin pain with average duration of symptoms 6 months; range 1 to 36 months. In the literature popliteal artery entrapment syndrome (PAES) has mostly been described in elderly population. This study looks at a younger age group. PURPOSE: Describe history, physical exam and ultrasound findings of patients with exertional calf pain. Prospective patients presented to Sports Medicine Clinic with exertional leg pain were characterized by age, sex, chief complaint(s), Doppler ultrasound findings, duration of symptoms and sport. METHODS: 12 patients (9 female and 3 male) were evaluated between January 2006 and September 2009. A tailored approach using real time, grayscale and color Doppler ultrasound targeted evaluation of the popliteal arteries bilaterally acquired before and after exercise stress. In addition, ankle/brachial indices before and after exercise were obtained. This approach uses four views: superficial femoral artery, proximal popliteal artery, mid popliteal artery, distal popliteal artery to predict the location and velocity of a potential popliteal artery entrapment. A positive sign of PAES occurs when three conditions are present: 50% or greater increase of systolic velocity in popliteal artery, Triphasic flow through the popliteal artery changes to a biphasic or monophasic Doppler wave form, Spectral broadening. RESULTS: Of the 12 patients, 58% increased 50% or greater in systolic velocity, seven recorded Doppler wave form changes from triphasic to biphasic with two patients recording triphasic to monophasic changes, and 75% recorded spectral broadening. Relatively few papers have concentrated on this application of Doppler Arterial Ultrasound in the evaluation of patients with exertional calf pain. The research is based on clinical data from Doppler pulse velocity waveforms and pressure measurements. CONCLUSIONS: Patients with exertional calf pain often go months or years without proper diagnosis. Recognition of symptoms and the use of proper analysis at an earlier stage may reduce morbidity of frank symptoms and enable the detection and treatment of PAES thereby reducing return time and increase long-term results.

PURPOSE:Dendritic cells are the most potent antigen-presenting cells and are critical to initiation of immune responses. Dendritic cells loaded ex vivo with tumor-associated antigen are being administered to cancer patients in an effort to jump-start a potent, cell-mediated anticancer immune response resulting in tumor shrinkage and clinical benefit.PATIENTS AND METHODS:Dendreon Corporation has designed three therapeutic vaccines using blood-derived dendritic cells loaded ex vivo with antigen: Provenge for prostate cancer; Mylovenge for multiple myeloma and other B-cell malignancies; and APC8024 for cancers expressing the HER-2/neu proto-oncogene.RESULTS:Preclinical studies demonstrated that blood dendritic cells matured spontaneously in short-term culture without growth factors, and that fusion of antigens with granulocyte-macrophage colony-stimulating factor enhances antigen uptake and presentation by blood dendritic cells. Phase I/II trials suggest that these dendritic cell-based vaccines are safe and well tolerated. Provenge has demonstrated antitumor activity in hormone-refractory prostate cancer; approximately 20% of patients experienced decreased prostate-specific antigen (i.e., PSA) levels and a similar percentage experienced disease stabilization. Double-blind, placebo-controlled, randomized trials in metastatic, asymptomatic hormone-refractory prostate cancer have been initiated. Phase II data on Mylovenge are similarly encouraging, and expanded phase II testing is ongoing in anticipation of opening phase III trials in 2002. APC8024 is in early clinical development and has shown significant capacity to elicit antigen-specific immune responses.CONCLUSION:Antigen delivery by ex vivo antigen-loaded dendritic cells may be an effective approach to cancer immunotherapy.

There is a pressing need for new agents for the treatment of hormone-resistant prostate cancer (HRPC). Pyrazoloacridine (PZA) has antitumor activity in several in vitro and in vivo tumor systems, and was selected for testing in clinical trials by the National Cancer Institute (NCI). We conducted a phase II trial of PZA for the treatment of HRPC. Seventeen male patients with HRPC were treated with PZA at 750 mg/m2 i.v. given over a period of 3 hr every 3 weeks. Response to therapy was assessed with serial measurements of serum prostate-specific antigen (PSA) and sequential imaging studies. The 17 patients were treated and fully evaluable. One patient experienced a significant decrease in PSA, from over 10,000 ng/ml to 423 ng/ml, along with an improvement in bone scan findings. However, no other patient obtained an objective or PSA response (overall PSA response rate = 5.9%). Median survival duration was 15.3 months. Toxicity was moderate. If PSA is used as a marker of response, single-agent PZA appears to lack efficacy in the treatment of HRPC. However, the one unambiguous response, and the favorable toxicity profile observed, may warrant further evaluation of this agent.

A 6-month-old infant presenting with pericardial effusion was found to have a malignant rhabdoid tumor of the heart. As visualized by two-dimensional echocardiography and subsequently by contrast-enhanced computerized axial tomographic scanning, the tumor arose from the left ventricular free wall and grew into the pericardial space. Despite two courses of single-agent chemotherapy with doxorubicin, the child died 3 months later. This is the first reported case of malignant rhabdoid tumor of the heart, and the fifth case of a primary cardiac malignancy in an infant.