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Biomedical subjects

M A Matthews

Publications and source records attributed to M A Matthews.

At least 55 records · Page 3Linked to original sources
PubMed1982

Inhibition of axoplasmic transport in the developing visual system of the rat-II, Quantitative analysis of alterations in transport of tritiated proline or fucose.

Developmental alterations in the amount of tritiated proline and fucose incorporated by retinal neurons and transported within axons of the optic nerve to the dorsal lateral geniculate nucleus and superior colliculus were measured at 1, 5, 10 and 15 days postnatal using quantitative autoradiography and liquid scintillation analysis. The amount of axon transport inhibition induced by introacular injections of colchicine (10-4 M-5 X 10-3M) and xylocaine (10-3 M-10-1 M) was also determined by this methodology. Grain counts of retinal autoradiograms obtained from animals of all ages employed in this study demonstrated that [3H] proline is rapidly incorporated by all retinal neurons but becomes increasingly concentrated within the inner nuclear, ganglion cell and optic fiber layers between 2h and 2 days after injection. [3H] fucose is preferentially taken up and concentrated within the plexiform and sensory element layers. Intraocular colchicine administered 24 h prior to isotope injection exhibited no significant effect on incorporation but depressed the amount of activity in the layer of optic fibers. Comparison of the effects of colchicine and xylocaine on axon transport of [3H] proline injected at 3 days of age revealed dose-dependent suppression of transport occurring up to six hr after isotope injection; however, with longer survival periods the effects of xylocaine were no longer significant whereas colchicine maintained suppression of axon transport to 20% of normal for periods of up to 10 days. Additionally, the rate and quantity of 3H] proline transported to the dorsal lateral geniculate nucleus and tectum of 1-15 day old animals was found to be inversely proportional to the age of the animal. Maximally-effective concentrations of colchicine, determined for each age level examined by the previous study to be highest compatible with the viability of the retino-fugal projection, 34 also reduced transport to from 20-40% of normal, being most effective in animals of 1-10 days of age. Autoradiographs of the optic disc demonstrated a colchicine-induced suppression of the amount of label in the exiting optic fibers and similar preparations of the tectum revealed an elimination of activity in the stratum griseum superficialis and stratum opticum which are normally heavily labeled following intraocular [3H] proline or fucose. Following [3H] fucose injection at 10 days of age, isotope appears in the contralateral visual cortex between 3 and 10 days later, indicating a substantial amount of transneuronal transfer of label which appeared to occur in concert with periods of maximal synaptogenesis. Injection of colchicine reduced the amount of label in the cortex to background levels. Concomitantly, autoradiographs of the dorsal lateral geniculate nucleus revealed cytoplasmic labeling of geniculate neurons in control animals but this was eliminated following colchicine injection...

Animals↗
PubMed1982

Inhibition of axoplasmic transport in the developing visual system of the rat-III. Electron microscopy and Golgi studies of retino-fugal synapses and post-synaptic neurons in the dorsal lateral geniculate nucleus.

Quantitative light and electron microscopy, together with Golgi methodology, were used to study alterations in retino-fugal terminals and postsynaptic neurons within the dorsal lateral geniculate nucleus of the rat at various intervals following inhibition of axoplasmic transport in the optic nerve induced by intraocular injections of colchicine from 1-20 days postnatal. Colchicine concentrations used in this study ranged from 10-5 M-10-2 M. These were selected on the basis of our measurements of axon transport suppression described in the preceding article. 61. The volume of the nucleus was determined by section planimetry and reconstruction. Growth of the contralateral dorsal lateral geniculate nucleus was significantly retarded by intraocular colchicine at 1 and 5 days of age, only achieving a volume of between 61-75% of the normal or the control (ipsilateral) nucleus depending upon dosage. Application of colchicine at 10 days of age resulted in minimal stunting of nuclear growth, (79-93% of normal). Mean numbers of neurons in the contralateral and ipsilateral nucleus remained stable throughout all postnatal ages examined suggesting that nuclear volume loss was caused principally by a reduction in the amount of neuropil. Golgi impregnation displayed dendritic stunting in relay neurons characterized by narrowing of the portion of the shaft between 40-80 micrometer from the soma and a reduced incidence of spinous protrusions, particularly those shown by other studies to engage the retino-fungal terminal. 27,69 A concomitant Sholl76 analysis of dendritic branching in relay neurons demonstrated no significant differences in the number of intersections between normal and experimental nuclei. No alterations were observed in intrinsic neurons. Electron microscopy of postsynaptic neurons following concentrations ranging from 10-4 M at birth revealed altered patterns of granular endoplasmic reticulum in many cells characterized by reduced numbers of cisternae and scattered instances of cisternal dilation, together with enhanced infolding of the nuclear membrane at 20 days postnatal. Those animals which were given 5 X 10-3 M-10-2 M colchicine demonstrated an increased incidence of cisternal dilation, loss of ribosomes, disruption of the nuclear membrane and occasionally, complete degeneration. A similar array of alterations took place following intraocular injection at 5 days of age; however, animals receiving colchicine at 10 days postnatal displayed minimal alterations in relay neurons. Synaptic glomeruli, which contain the retinofugal terminal, displayed dose and age-dependent reduction in the size of the presynaptic element of the complex following intraocular colchicine, together with fewer post-synaptic spinous protrusions. Synaptic vesicles remained normal in appearance and distribution and our quantitative analysis demonstrated no loss of such terminals in accordance with colchicine concentrations which were previously found not to be lethal to retinal ganglion cells and optic axons.

Animals↗
PubMed1980

Isolation and characterization of brain endothelial cells: morphology and enzyme activity.

Microvessels were isolated from rat brain using a double collagenase treatment which removed the endothelial basement membranes. The isolate was characterized by intact luminal and abluminal membranes and an absence of pericytes and astrocyte membranes. Minimal contamination by 5'-nucleotidase, an enzyme believed exclusively localized within the plasma membranes of neuroglia, established the purity of the isolated microvessels. Enrichment of alkaline phosphatase and gamma-glutamyl transpeptidase activity in microvessel preparations supports the endothelial localization of these enzymes.

5'-Nucleotidase↗
PubMed1980

Qualitative and quantitative effects of ACTH, piromen, cytoxan and isobutyl-2-cyanoacrylate treatments following spinal cord transection in rats.

Adult, male, Long-Evans hooded rats were subjected to a spinal cord transection in the mid-thoracic region. Following surgery, animals were divided into groups for treatments with ACTH, Piromen, isobutyl-2-cyanoacrylate and Cytoxan. Animals were sacrificed at varying intervals from 7-180 days. Horizontal sections of the lesion site were stained with the Bodian silver and Gomori trichrome techniques and numbers of nerve fibers counted within the lesion. Statistical analysis of the quantitative data indicated that Piromen and Cytoxan, respectively, were significantly more effective than the other treatments in promoting regeneration of nerve fibers into the scar. Microcysts appeared adjacent to the lesion in all animals early in the postoperative period and coalesced to form large cavitations which continued to enlarge throughout the postoperative period. Although nerve fibers appeared to traverse the lesion, no return of function was observed.

Adrenocorticotropic Hormone↗
PubMed1977

Reactive alterations in non-neuronal elements of the degenerating ventrobasal complex of immature and mature rats. An electron microscopic study.

Sprague-Dawley albino rats ranging in age from neonate to 60 days postnatal (dpn)were subjected to cortical extirpations encompassing the SmI somato-sensory projection fields of neurons in the ventrobasal (VB) complex. Eectron microscopy of this region reveals degenerative changes in VB neurons, the rate and severity of which is inversely proportional to the age of the animal (Matthews et al., 1977). Numerous, distinctive non-neuronal elements, similar to those infiltrating the perivascular space of some vessels in the area, rapidly accumulate within the zone of degeneration in animals lesioned between 0 and 9 dpn. These display dense, heterochromatin nuclei, concentrations of of free ribosomes and rosettes, and pleomorphic dense bodies which become more evident as further reactive transformations accompany the phagocytic incorporation of degenerating neuronal remnants. Other non-neuronal elements exhibit a euchromatin nucleus, bundles of microtubules, and fewer free ribosomes. Such cells are also capable of phagocytosis and production of dense bodies. Both variants are comparable in appearance to the "M" cells of previous reports (Matthews and Kruger, 1973b). Cortical lesions of older animals result in the appearance of "M" cells in VB; however, the population densities observed in the immature VB are not achieved. Conversely, astrocytic hypertrophy, associated with the increased incidence of degenerating boutons in the more mature animal, represents a prominent response to injury which does not occur to a significant extent in younger animals. Morphological criteria for determining the nature of some "M" cells are given for a discussion of their presumptive derivation from various mesodermal progenitors and a brief consideration of other hypothesized origins.

Animals↗
PubMed1976

A sausage-associated outbreak of trichinosis in Illinois.

Twenty-three of 50 members of an extended Dutch-German family and their close friends who ate raw homemade summer sausage became ill with trichinosis; 12 patients were hospitalized for an average of 10 days each. The sausage had been made in three different batches according to an old family recipe. One of the batches made from USDA-inspected pork was found to contain Trichinella spiralis larvae by two Illinois State laboratories. The other two batches were negative. Seventeen of the 23 patients submitted information on medical expenses incurred and wages lost because of the outbreak. These costs totaled almost $20,000. There is need for a nationwide program for controlling trichinosis in swine.

Adolescent↗