Browsing by Author "VERGARA, J"

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    AXONAL MICROTUBULES - COMPARATIVE ANATOMY IN VERTEBRATES, INCLUDING MAN
    (1991) VERGARA, J; SERRA, M; SAITUA, F; ITURRIAGA, R; ALVAREZ, J
    The microtubular density was assessed with the electron microscope in 3-mu-m myelinated fibers, myelin excluded, of 11 species from the following classes: Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia. The average for all species was 20.6 microtubules/mu-m2. Dispersion of values was restricted as shown by a coefficient of variation of 15.8. The microtubular content of nonmedullated axons was assessed in trout, lizard, finch, and man. In the four species, the number of microtubules increased with the cross sectional area of the axon. In trout, lizard and finch, the microtubular density decreased from over 100 microtubules/mu-m2 in fibers smaller than 0.1-mu-m2 to about 30 in 1-mu-m2 fibers; in axons of equal size, the packing of microtubules of nonmedullated was similar between them, and with reported values for peripheral axons of cat and rat. In man, the microtubular density of nonmedullated fibers exhibited only a mild decrease with the axonal size. In the finch, myelinated and nonmedullated axons overlapped in the range 0.23-0.60-mu-m2 and both groups exhibited similar microtubular densities. We conclude that the packing of microtubules of the vertebrate peripheral axon is a feature largely conserved during evolution.
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    NERVE REGENERATION IS IMPROVED BY INSULIN-LIKE GROWTH FACTOR-I (IGF-I) AND BASIC FIBROBLAST GROWTH-FACTOR (BFGF)
    (1993) VERGARA, J; MEDINA, L; MAULEN, J; INESTROSA, NC; ALVAREZ, J
    In rat sciatic nerves, IGF-I or bFGF was applied distal to a crush to evaluate their effects upon the restoration of the neuromuscular function. In comparison with the recovery following a simple crush, treatment with growth factors resulted in (i) enhanced elongation of regenerating axons (+ 24 %) up to day 3 post lesion (PL); (ii) more sprouts at early times; (iii) reduced participation of macrophages in the removal of the degenerating myelin in the first week PL; (iv) restoration of the neuromuscular transmission 2 days earlier; (v) a prolonged relaxation time and a reduced specific tetanic tension at week 3 PL but not at week 7 PL. Other indicators of recovery such as conduction velocity of nerve impulse, muscle weight, specific twitch tension, and time to peak were not affected by bFGF or IGF-I. Results suggest that IGF-I and bFGF affect locally Schwann cells and axons, and also the neuron as a whole, including its trophic function. We conclude that IGF-I and bFGF applied to the nerve, albeit moderately, improve the recovery of the neuromuscular function.
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    THE AXONAL MICROTUBULAR DENSITY IS HIGHER THAN NORMAL IN FIBERS INNERVATING SPASTIC MUSCLES
    (1992) VERGARA, J; REPETTO, G; ALVAREZ, J
    In infants with spastic disorders and with congenital dysplasia of the hip (CDH), the microtubular content of nonmedullated and myelinated fibres of the anterior obturator nerves was studied with the electron microscope, In CDH infants, the microtubular content of nonmedullated and myelinated fibres was similar to values reported for experimental animals. In spastic patients, the microtubular content of nonmedullated fibres was similar to that found in CDH patients while the microtubular densities of 3- and 10-mu-m myelinated fibres were 37.5 and 16.7 microtubules/mu-m2, respectively, or 100% and 43% greater than corresponding values of CDH patients, We propose that the high firing rate determines the abnormally high microtubular content of myelinated axons supplying spastic muscles.