Origin and significance of Si and O isotope heterogeneities in Phanerozoic, Archean, and Hadean zircon.

Hydrosphere interactions and alteration of the terrestrial crust likely played a critical role in shaping Earth's surface, and in promoting prebiotic reactions leading to life, before 4.03 Ga (the Hadean Eon). The identity of aqueously altered material strongly depends on lithospheric cycling of abundant and water-soluble elements such as Si and O.

Legionella bozemanii pulmonary abscess in a pediatric allogeneic stem cell transplant recipient.

Legionella spp. infections are often considered in the differential diagnosis of pneumonia in adults. This case report describes a pediatric stem cell transplant recipient presenting with cavitary pulmonary disease secondary to Legionella bozemanii infection.

Hypersusceptibility to invasive pneumococcal infection in experimental sickle cell disease involves platelet-activating factor receptor.

Children with sickle cell disease have a 600-fold increased incidence of invasive pneumococcal disease. Platelet-activating factor receptor (PAFr) mediates pneumococcal invasion, and up-regulation of PAFr on chronically activated endothelia could contribute to increased bacterial invasion. Mice transplanted with sickle cell bone marrow developed more extensive infection, and 57% died, compared with 16% of wild-type mice.

Quinupristin-dalfopristin nonsusceptibility in pneumococci from sickle cell disease patients.

Sickle cell disease (SCD) is a risk factor for fatal pneumococcal infection. Nonsusceptibilty to quinupristin-dalfopristin (Q-D) was absent from 105 non-SCD-associated pneumococcal isolates but was present in 33/148 (22%) SCD-associated isolates. One-third of the isolates harbored a known resistance mechanism.

Incidence and etiologies of complicated parapneumonic effusions in children, 1996 to 2001.

Background: The incidence and causative organisms associated with complicated parapneumonic effusions in children with community-acquired pneumonia are likely to have changed during the past several years.

Methods: Data regarding clinical and laboratory features were abstracted retrospectively from medical records of 76 subjects with complicated parapneumonic effusions at a tertiary children's hospital from 1996 through 2001. Incidence rates per 10 000 hospital discharges and per 1000 patients with nonviral pneumonia were calculated.