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Biomedical subjects

A E Fallon

Publications and source records attributed to A E Fallon.

6 recordsLinked to original sources
PubMed1999

Fetal anemia and apoptosis of red cell progenitors in Stat5a-/-5b-/- mice: a direct role for Stat5 in Bcl-X(L) induction.

The erythropoietin receptor (EpoR) is essential for production of red blood cells; a principal function of EpoR is to rescue committed erythroid progenitors from apoptosis. Stat5 is rapidly activated following EpoR stimulation, but its function in erythropoiesis has been unclear since adult Stat5a-/-5b-/- mice have normal steady-state hematocrit. Here we show that Stat5 is essential for the high erythropoietic rate during fetal development. Stat5a-/-5b-/- embryos are severely anemic; erythroid progenitors are present in low numbers, show higher levels of apoptosis, and are less responsive to Epo. These findings are explained by a crucial role for Stat5 in EpoR's antiapoptotic signaling: it mediates the immediate-early induction of Bcl-X(L) in erythroid cells through direct binding to the Bcl-X promoter.

Anemia↗
PubMed1998

The prolactin receptor rescues EpoR-/- erythroid progenitors and replaces EpoR in a synergistic interaction with c-kit.

We recently showed that a retrovirally transduced prolactin receptor (PrlR) efficiently supports the differentiation of wild-type burst-forming unit erythroid (BFU-e) and colony-forming unit erythroid (CFU-e) progenitors in response to prolactin and in the absence of erythropoietin (Epo). To examine directly whether the Epo receptor (EpoR) expressed by wild-type erythroid progenitors was essential for their terminal differentiation, we infected EpoR-/- progenitors with retroviral constructs encoding either the PrlR or a chimeric receptor containing the extracellular domain of the PrlR and intracellular domain of EpoR. In response to prolactin, both receptors were equally efficient in supporting full differentiation of the EpoR-/- progenitors into erythroid colonies in vitro. Therefore, there is no requirement for an EpoR-unique signal in erythroid differentiation; EpoR signaling has no instructive role in red blood cell differentiation. A synergistic interaction between EpoR and c-kit is essential for the production of normal numbers of red blood cells, as demonstrated by the severe anemia of mice mutant for either c-kit or its ligand, stem cell factor. We show that the addition of stem cell factor potentiates the ability of the PrlR to support differentiation of both EpoR-/- and wild-type CFU-e progenitors. This synergism is quantitatively equivalent to that observed between c-kit and EpoR. Therefore, there is no requirement for an EpoR-unique signal in the synergistic interaction between c-kit and EpoR.

Animals↗
PubMed1998

The relationship between personality psychopathology and aggressive behavior in research volunteers.

Theorists and clinicians have long believed that personality psychopathology is a risk factor for aggressive behavior. Previous investigations in this area, however, have provided mixed results. In this study, the relationship between personality psychopathology and aggressive behavior was examined in 137 research volunteers. The influences of gender and coexisting major mental disorders were statistically controlled. Aggressive behavior was associated with criteria for 7 of the 11 personality disorders listed in the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.). Except for schizoid criteria, all relationships with aggressive behavior were in the positive direction. When all personality disorders were considered simultaneously, paranoid and passive-aggressive criteria were significant predictors of aggressive behavior.

Adolescent↗
PubMed1984

The child's conception of food: the development of food rejections with special reference to disgust and contamination sensitivity.

Structured interviews with 3.5-12-year-old children and their mothers were directed at documenting the development of 4 psychological categories of food rejection. The first to appear is rejection based purely on sensory characteristics, usually taste ( distastes ). Rejection based purely on anticipated harm following ingestion appears next (danger). Finally, the oldest children and adults show rejection based on the idea of what something is or where it comes from. This ideational type of rejection further differentiates into affectively laden rejections of substances that become offensive ( disgusts ) and more neutral rejections of substances as simply not food (inappropriate). A critical psychological feature of disgusting substances in adults is that they are "contaminants": they render an otherwise liked food inedible if present even in trace amounts, or if associated with a liked food. Contamination sensitivity is not present in the younger subjects, and appears gradually in the age range studied. Young children are unaware of the physical chemistry of solutions (e.g., diffusion and its lack of reversibility) and therefore do not show a "contamination response."

Attitude↗