RESUMEN
Pluto and its satellite, Charon (discovered in 1978; ref. 1), appear to form a double planet, rather than a hierarchical planet/satellite couple. Charon is about half Pluto's size and about one-eighth its mass. The precise radii of Pluto and Charon have remained uncertain, leading to large uncertainties on their densities. Although stellar occultations by Charon are in principle a powerful way of measuring its size, they are rare, as the satellite subtends less than 0.3 microradians (0.06 arcsec) on the sky. One occultation (in 1980) yielded a lower limit of 600 km for the satellite's radius, which was later refined to 601.5 km (ref. 4). Here we report observations from a multi-station stellar occultation by Charon, which we use to derive a radius, R(C) = 603.6 +/- 1.4 km (1sigma), and a density of rho = 1.71 +/- 0.08 g cm(-3). This occultation also provides upper limits of 110 and 15 (3sigma) nanobar for an atmosphere around Charon, assuming respectively a pure nitrogen or pure methane atmosphere.
RESUMEN
Twenty-seven patients with histologically proved advanced breast cancer were given VP 16-213 and cyclophosphamide. Twenty-one had shown resistance to other chemotherapy schedules and six had experienced relapse during adjuvant chemotherapy. There were four complete responses (15%) and seven partial responses (26%). Median survival was 61 weeks and median duration of response was 31.4 weeks. All patients experienced gastrointestinal toxicity and 22 patients (81%) showed bone marrow toxicity. This regimen is effective in advanced breast cancer resistant to other chemotherapy regimens.
Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Ciclofosfamida/administración & dosificación , Etopósido/administración & dosificación , Podofilotoxina/análogos & derivados , Adulto , Anciano , Ciclofosfamida/efectos adversos , Evaluación de Medicamentos , Sinergismo Farmacológico , Quimioterapia Combinada , Etopósido/efectos adversos , Femenino , Humanos , Persona de Mediana Edad , Metástasis de la Neoplasia , PronósticoRESUMEN
The clinical and pathological features of two cases of retrorectal cyst-hamartoma are presented. Both lesions were characterized by the presence of cysts lined by mucus-producing, ciliated and transitional epithelium. The anatomical and histological findings in our cases of retrorectal cyst-hamartoma are in favor of an embryologic origin from remnants of the postanal gut. The differential diagnosis includes teratomas, dermoid cysts, duplication cysts of the rectum, anal gland cysts, and anal gland carcinomas. To avoid complications, particularly malignant transformation, early complete excision is recommended.
