Health-related quality of life in long-term survivors of pediatric liver transplantation.

The purpose of this study is to measure the health-related quality of life (HRQOL) in children who are long-term survivors of liver transplantation and to pilot the Liver Transplant Disability Scale (LTDS), a newly developed 12-point scale that quantifies chronic medical disability related to liver transplantation. This study is a cross-sectional survey of 51 children surviving liver transplantation by at least 2 years, with a median age of 4.94 years. Functional capacity and utility scores were measured by the Health Utilities Index Mark II (HUI2), and chronic disease-specific medical disability was measured by the LTDS. HUI2 results were compared with a reference population. LTDS scores were compared with utility scores and patient survival 3 years later. Ninety percent of the study patients had functional deficits compared with 50% of controls. Functional impairment was typically mild. The resulting mean utility score, 0.86 +/- 0.13 (0 = dead, 1 = perfect health), was significantly less than that of the reference population, 0.95 +/- 0. 07 (P <.001). LTDS scores ranged from 0 (no disability) to 6 (moderate disability). Seventy-one percent of the children had mild disability (scores 0 to 3), and 29% had moderate disability (scores 4 to 6). LTDS scores did not correlate with utility scores but were predictive of survival. The majority of pediatric liver transplant recipients have mild functional deficits. Their utility scores reflected a high level of HRQOL but were significantly less than those of a reference population. The majority also had mild medical disability, predominantly delayed growth. Medical disability did not correlate with HRQOL but predicted survival 3 years later.

Trk receptors function as rapid retrograde signal carriers in the adult nervous system.

During development target-derived neurotrophins promote the survival of neurons. However, mature neurons no longer depend on the target for survival. Do target-derived neurotrophins retain retrograde signaling functions in mature neurons, and, if so, how are they executed? We addressed this question by using a phosphotyrosine-directed antibody to locate activated Trk receptors in adult rat sciatic nerve. We show that catalytically active Trk receptors are located within the axon of adult rat sciatic nerve and that they are distributed throughout the length of the axons. These catalytically active receptors are phosphorylated on tyrosine at a position that couples them to the signal-generating proteins Ras and PI3 kinase. Neurotrophin applied at sciatic nerve terminals increases both catalytic activity and phosphorylation state of Trk receptors at distant points within the axons. Trk activation initiated at the nerve terminals propagates through the axon toward the nerve cell body at an initial rate that exceeds that of conventional vesicular transport. However, our data suggest that this rapid signal is nevertheless vesicle-associated. Thus, in mature nerves, activated Trk receptors function as rapid retrograde signal carriers to execute remote responses to target-derived neurotrophins.