Regulation of mouse embryonic stem cell neural differentiation by retinoic acid.

Pluripotent mouse embryonic stem cells (ESCs) derived from the early blastocyst can differentiate in vitro into a variety of somatic cell types including lineages from all three embryonic germ layers. Protocols for ES cell neural differentiation typically involve induction by retinoic acid (RA), or by exposure to growth factors or medium conditioned by other cell types. A serum-free differentiation (SFD) medium completely lacking exogenous retinoids was devised that allows for efficient conversion of aggregated mouse ESCs into neural precursors and immature neurons. Neural cells produced in this medium express neuronal ion channels, establish polarity, and form functional excitatory and inhibitory synapses. Brief exposure to RA during the period of cell aggregation speeds neuronal maturation and suppresses cell proliferation. Differentiation without RA yields neurons and neural progenitors with apparent telencephalic identity, whereas cells differentiated with exposure to RA express markers of hindbrain and spinal cord. Transcriptional profiling indicates a substantial representation of transit amplifying neuroblasts in SFD cultures not exposed to RA.

Acute idiopathic pulmonary haemorrhage in infancy: case report and review of the literature.

This report presents the case of a 4-month-old male infant with recurrent bouts of haemoptysis for which no cause could be detected after extensive investigation. Literature reports of this condition from other geographic locations around the world are reviewed, together with epidemiologic studies attempting to provide a link with certain environmental exposures, toxic and infectious. A diagnostic entity of acute idiopathic pulmonary haemorrhage in infancy has recently been proposed. To my knowledge, this is the first case reported from New Zealand. Although the incidence of such reported cases appears to be rare, they constitute an interesting public health problem, particularly because some of the risk factors appear to overlap with risk factors for sudden infant death. They can therefore trigger an investigation into the home and outdoor environments, and may provide valuable insights into a possible underlying genetic factor and potentially harmful exposures in the modern urban or rural settings.