Browsing by Author "FERNANDEZ, HL"

Now showing 1 - 8 of 8
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    ACTIN-LIKE FILAMENTS IN SYNAPTOSOMES DETECTED BY HEAVY-MEROMYOSIN BINDING
    (1976) INESTROSA, NC; FERNANDEZ, HL; GARRIDO, J
    Cat forebrain synaptosomes were prepared to investigate the presence of actin-like proteins. Actin-like filaments were demonstrated using a heavy meromyosin binding technique. Decorated filaments form networks inside the synaptosomes and were frequently seen in relation to membranes and synaptic vesicles. Using SDS[sodium dodecylsulfate]-polyacrylamide gel electrophoresis, a band corresponding to actin appeared to be one of the major constituents of synaptosomal fractions; this confirmed the work of Fine and coworkers. The significance of actin-like filaments in relation to axoplasmic transport was briefly discussed.
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    GANGLIOSIDES AND SIALOGLYCOPROTEINS IN NORMAL AND DENERVATED RAT DIAPHRAGM MUSCLE
    (1982) INESTROSA, NC; FERNANDEZ, HL
    Ganglioside- and glycoprotein-bound sialic acid in endplate and non-endplate regions of rat diaphragm muscles were assessed 1-16 days after phrenic nerve transection. Sialic acid in glycoproteins (90% of total) and gangliosides (10% of total) from intact hemidiaphragms was distributed uniformly throughout endplate and nonendplate regions. After denervation, the total sialic acid per hemidiaphragm increased (days 1-4) and reached a maximum level (days 8-12) which remained constant (days 12-16). These sialic acid changes reflected increments in gangliosides (40% over control), which occurred simultaneously in endplate and non-endplate regions (days 1-8), and increments in sialoglycoproteins (70%-80% over control), which took place much earlier in endplate (days 1-8) than in nonendplate (days 8-14) regions. Maintenance of both sialoglycoproteins and gangliosides depends upon an intact innervation, probably through separate mechanisms involving different neurogenic factors.
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    IS THERE A CORRESPONDENCE BETWEEN HALF-LIVES OF MOTOR ENDPLATE ACETYLCHOLINESTERASE AND JUNCTIONAL ACETYLCHOLINE RECEPTORS
    (1977) INESTROSA, NC; FERNANDEZ, HL
    To study the turnover rate of motor endplate acetylcholinesterase (AChE), we have treated the hypoglossal nerve [rat] with 10 mM colchicine, a drug that produced a reversible decrease of AChE from geniohyoid muscle endplates. The return of AChE to the normal steady-state level was used to calculate an AChE half-life of 4.6 days. This value was very close to that obtained for the half-life of junctional acetylcholine receptors (AChR). Both macromolecules seem to have the same turnover rate.
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    MUSCLE ENZYMATIC CHANGES INDUCED BY BLOCKAGE OF AXOPLASMIC-TRANSPORT
    (1976) INESTROSA, NC; FERNANDEZ, HL
    The activity of malic dehydrogenase, pyruvic kinase and phosphorylase b was measured in the geniohyoid muscle of the cat after injection of 10 mM colchicine into the hypoglossal nerve. Experiments performed 1-60 days after the injection showed that the activity of the 3 enzymes gradually decreased (day 4-5), reached a maximum fall (day 10-25) and subsequently returned to control values (day 30-60). Concomitant to these enzymatic alterations, the muscles showed fibrillation and ACh [acetylcholine] hypersensitivity; however, in contrast to denervation, the drug had no effect on nerve conduction, effective neuromuscular transmission and the ultrastructure of motor end plates. Experiments with (3H) colchicine indicated that the observed changes were brought about by the drug acting directly on the motor axons rather than on the muscle cells. The transsynaptic effects induced by colchicine treatment to the nerve can be ascribed to a temporary interruption of axoplasmic transport. Neurotrophic regulation of some muscle-soluble enzymes may partly depend on the normal operation of the axoplasmic system.
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    NEUROTROPHIC EFFECTS - AXOPLASMIC-TRANSPORT INVOLVEMENT IN REGULATION OF SKELETAL-MUSCLE SOLUBLE-PROTEINS
    (1976) FERNANDEZ, HL; RAMIREZ, BU
    Skeletal muscle soluble proteins were assayed by polyacrylamide gel disc-electrophoresis at different times (4-36 days) after injection of 10 mM colchicine into the motor nerve [of cats] and after denervation. Effects of drug-induced axoplasmic transport blockage differed from those of denervation as to quantitative changes in the protein concentration of certain bands. Axoplasmic transport is apparently involved in the neural control of a number of muscle proteins. This does not invalidate the participation of acetylcholine and muscle activity in the regulation of muscle metabolism.
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    PLATELETS ARE THE PRIMARY SOURCE OF AMYLOID BETA-PEPTIDE IN HUMAN BLOOD
    (1995) CHEN, M; INESTROSA, NC; ROSS, GS; FERNANDEZ, HL
    The main component of Alzheimer's disease (AD) amyloid deposits is amyloid beta-peptide (A beta), a fragment of the larger amyloid precursor protein (APP). The cellular source of A beta is not known, but a circulatory origin has been postulated. We studied human blood from healthy individuals and found that platelets account for almost 90% of the total anti-A beta immunoreactivity detected in whole blood. Using reverse-phase HPLC, we identified a platelet peptide which corresponds to A beta by three criteria. (a) it shares a retention time with the synthetic A beta(1-40) peptide in two consecutive HPLC tests; (b) it interacts with two anti-A beta antibodies in separate ELISAs; and, (c) its partial N-terminal amino acid sequence closely matches that of A beta. The detection of this peptide in platelets indicates that, aside from the well-known non-amyloidogenic (secretory) pathway, the processing of APP in platelets from healthy individuals also involves an amyloidogenic pathway. These findings are consistent with the view that platelets are one of the major sources of A beta in the circulation. (C) 1995 Academic Press, Inc.
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    TURNOVER RATES OF CAT SKELETAL-MUSCLE SOLUBLE ENZYMES
    (1982) INESTROSA, NC; FERNANDEZ, HL
    Turnover rates of cat geniohyoid muscle glycolytic and glycogenolytic enzymes were studied after local application of 10 mM colchicine into the hypoglossal nerve. Drug treatment caused reversible decreases in the activities of malic dehydrogenase, pyruvic kinase and phosphorylase-b, which have been previously ascribed to a temporary interruption of axonal transport. Kinetics of the return of the enzymic activities to normal steady-state levels were analyzed to calculate half-lives of 16 days for malic dehydrogenase, 14 days for pyruvic kinase and 21 days for phosphorylase-b. The turnover rate of certain muscle soluble enzymes is partly dependent on the subcellular localization where the enzymes play their physiological role.