Binding and retrograde transport of leukemia inhibitory factor by the sensory nervous system.

Leukemia inhibitory factor (LIF), a peptide growth factor with multiple activities, has recently been shown to support the generation and survival of sensory neurons in cultures of mouse neural crest and dorsal root ganglia (DRG). We have conducted binding experiments with 125I-LIF on cultures of DRG to determine the receptor distribution for LIF on these cells and found that at least 60% of the sensory neurons in the cultures bound 125I-LIF, all of which could be eliminated by the addition of unlabeled LIF. The other cells in the culture, which morphologically appeared to be Schwann cells, did not bind appreciable quantities of 125I-LIF. In order to investigate whether LIF is retrogradely transported to sensory neurons in vivo, 125I-LIF was injected into the footpads and gastrocnemius muscles of newborn and adult mice, following sciatic nerve ligation. Radioactivity accumulated in the distal portion of the sciatic nerve, indicating retrograde transport of LIF. Subsequent experiments on mice with unligated sciatic nerves showed that 125I-LIF is specifically transported into the sensory neurons of the DRG. There was no apparent transport of 125I-LIF into motor neurons in the spinal cord. These experiments demonstrate that LIF can specifically bind to and be transported by sensory neurons and further support the idea that LIF acts as a target-derived neurotrophic factor, analogous to NGF.     

Immunoadsorbent purification of carcinoembryonic antigen using a monoclonal antibody: a direct comparison with a conventional method

Carcinoembryonic antigen (CEA) has been extracted and purified by two different methods from a single aqueous homogenate of liver metastases from a primary adenocarcinoma of the colon, thus enabling direct comparison to be made between a conventional technique using gel filtration and a monoclonal antibody immunoadsorbent method. Yield, immunoreactivity and purity have been determined in both cases by direct weighing, enzyme-linked immunoadsorbent assay, radioimmunoassay and SDS-polyacrylamide gel electrophoresis. Reactivity of the antigen with monoclonal and polyclonal anti-CEA antibodies recognising different epitopes was analysed by Western blotting. There appears to be no significant difference in immunoreactivity or purity by these criteria, but the immunoadsorbent method gave a higher yield of CEA for far less expenditure of time and effort. A variant of CEA with a lower molecular weight was also identified in both preparations.     

Leukaemia Inhibitory Factor or Related Factors Promote the Differentiation of Neuronal and Astrocytic Precursors within the Developing Murine Spinal Cord

Previously we have shown that leukaemia inhibitory factor (LIF) potentiates the development of murine spinal cord neurons in vitro , suggesting that it, or related factors, may play an important regulatory role in neuronal development. We have further investigated this role and show here that the generation of neurons in cultures of embryonic day 10 spinal cord cells is inhibited by antibodies to the β subunit of the LIF receptor. Since there are more undifferentiated precursors in antibody-treated cultures than in control and LIF-treated cultures, it is concluded that the primary action of LIF, or related molecules, is to promote neuronal differentiation, not precursor survival. In addition, the failure of LIF to support neuronal survival in the period immediately following differentiation suggests that the increased numbers of neurons generated with LIF are not attributable to its neurotrophic action. By selecting neuronal precursors on the basis of their inability to express class I major histocompatibility complex molecules, it was shown that LIF acted directly upon these cells and not via an intermediary cell. LIF also appears to be involved in regulating the differentiation of astrocytes, since it increases the number of glial fibrillary protein (GFAP)-positive cells present in the cultures and since the spontaneous production of GFAP-positive cells is blocked by antibodies to the LIF β receptor. These findings suggest that LIF or related factors promote the differentiation of neural precursors in the spinal cord, but that they are not involved in preferentially promoting precursors down a specific differentiation pathway.     

Systemic drug profiles in adult optometric outpatients

Systemic drug profiles of adult patients seen in an optometric outpatient setting were determined. The sample consisted of 502 subjects, of whom 214 were taking known medication, 267 were not taking drugs, and 21 subjects were taking unidentified medication. The most frequently used drugs and drug groups were identified and compared to a 1986 national survey that ranked the most frequently prescribed systemic medications. Drug distribution by age, sex, and race of the 22 most frequently prescribed drugs was determined. Implications for the ophthalmic practitioner are discussed.     

Evaluation of a burn prevention program in a public school system.

The "Learn Not to Burn" prevention program is a burn prevention curriculum sponsored by the North Carolina Jaycee Burn Center, the State Department of Public Instruction, and the North Carolina Department of Insurance Fire and Rescue Division. The goal of the program is to reduce burn-related deaths and injuries in North Carolina through burn prevention education by making the "Learn Not to Burn" curriculum available to primary school children across the state at no cost to the schools. The curriculum instrument is a reusable notebook that provides a means for teachers to integrate burn prevention into regular class subject areas. At the time of initiation of this study approximately 70% of the school systems in North Carolina had been provided with the "Learn Not to Burn" curriculum.