M L Higgins

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The exposure of neuronal and glial cell processes to a large number (up to 300) of 12-nsec laser pulses at a wavelength of 337 nm and energy densities below the threshold for nonlinear absorption results in a gradual, gentle process transection in the laser focus. Within 10 to 20 sec after cessation of firing, the process pinches in the target area. During(More)
Ultrastructural changes in the cytoplasm of transected dendrites have been studied with serial section electron microscopy 10 to 12 min after the lesion. Dendrites from large multipolar neurons in mouse spinal monolayer cultures were selected 4 weeks after seeding and cut with a pulsed UV laser microbeam. The data reveal cytoplasmic damage gradients which(More)
A serious lack of knowledge about central nervous system trauma is encountered on the cellular level where the inability to create precise experimental lesions of known magnitude has limited our understanding of the reactions of single cells to injury. We used a laser cell surgery technique developed in this laboratory to manipulate neurons in a controlled(More)
To determine the contributions of calcium to development of ultrastructural damage and neuronal death after mechanical injury, we amputated primary dendrites from over 300 cultured mammalian spinal neurons under normal (1.8 mM) or low (less than or equal to 30 microM) calcium conditions. Two general categories of early ultrastructural change were seen in(More)
Recent advances in incentive theory stress the multi-dimensional nature of agent effort and particularly the case where workers can improve the performance of others through 'helping' efforts. This paper provides a simple model of an agent's incentive to help depending on the compensation package, the cost of monitoring, and the allocation of tasks. We then(More)
The 15-azasteroid, 1,10,11,11a-tetrahydro-11a-methyl-2H naphth (1,2-g)indol-7-o1, inhibits the growth of the cell culture lines KB and L-M as well as several strains of bacteria. The inhibition of growth is reversed following removal of the steroid from the growth medium. Using in vitro grown L-M cells, the compound inhibited the transport of amino acids(More)
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