RESUMO
Tropical glaciers have retreated over recent decades, but whether the magnitude of this retreat exceeds the bounds of Holocene fluctuations is unclear. We measured cosmogenic beryllium-10 and carbon-14 concentrations in recently exposed bedrock at the margin of four glaciers spanning the tropical Andes to reconstruct their past extents relative to today. Nuclide concentrations are near zero in almost all samples, suggesting that these locations were never exposed during the Holocene. Our data imply that many glaciers in the tropics are probably now smaller than they have been in at least 11,700 years, making the tropics the first large region where this milestone has been documented.
RESUMO
Structural features associated with the antimalarial activity of the marine natural product crambescidin 800 were studied using synthetic analogues of the related compound ptilomycalin A. The study suggests that the guanidine moiety is cytotoxic, whereas the spermidine-containing aliphatic chain increases activity. The most active analogue, compound 11, had in vitro activity against Plasmodium falciparum strain 3D7 (IC50=490 nM) that was stronger than the in vitro activity against murine L5178Y cells (IC50 = 8.5-59 microM). In vitro growth inhibition of liver stages of P. yoelii yoelii in mouse hepatocytes was observed (IC50 = 9.2 microM). The compound did not significantly prolong median survival time after a single subcutaneous administration of 80 mg/kg in P. berghei-infected mice. Compound 11 did not cause DNA fragmentation in an in vitro micronucleus assay.
Assuntos
Antimaláricos/química , Antimaláricos/farmacologia , Guanidina/análogos & derivados , Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Plasmodium yoelii/efeitos dos fármacos , Compostos de Espiro/química , Compostos de Espiro/farmacologia , Animais , Antimaláricos/toxicidade , Células Cultivadas , Modelos Animais de Doenças , Eritrócitos/parasitologia , Guanidina/química , Guanidina/farmacologia , Guanidina/toxicidade , Hepatócitos/parasitologia , Camundongos , Estrutura Molecular , Testes de Sensibilidade Parasitária , Compostos de Espiro/toxicidade , Análise de SobrevidaRESUMO
This article describes surgical methods for resecting uveal melanoma, emphasizing techniques for preventing complications. Outcomes of surgery and the indications, contraindications, and controversies of resecting uveal melanoma are discussed.
Assuntos
Melanoma/cirurgia , Procedimentos Cirúrgicos Oftalmológicos/métodos , Neoplasias Uveais/cirurgia , Anestesia/métodos , Humanos , Melanoma/patologia , Complicações Pós-Operatórias/prevenção & controle , Prognóstico , Resultado do Tratamento , Neoplasias Uveais/patologiaRESUMO
The use of profound induced hypotension to provide better operating conditions for surgery is long established. However, it is a controversial technique and it may be argued that it is inappropriate in modern anaesthetic practice. A currently used technique is reviewed against the benchmark of a lawsuit concerning profound hypotension.