Biomedical subjects
Publications and source records attributed to M K Boylan.
Two patients requiring emergency cardiac surgery following the administration of streptokinase are described. In each case aprotinin was given to counteract the haemorrhagic effects of the streptokinase.
The development of tachykinins in the neostriatum was determined qualitatively in order to characterize the ontogeny of an early-forming neostriatal peptidergic system. Tachykinins were detected by immunohistochemistry in fetal, postnatal, and adult cats. Neostriatal cells and neurites expressed tachykinins as early as fetal age 30 and increased in frequency progressively with age. Initial tachykinin expression occurred in neostriatal neurons during their postmitotic migration. In the head of the caudate nucleus, clusters of tachykinin-containing cells and fibers formed between fetal days 35 and 45, when the distribution of labeled neurons changed from a dispersed to an aggregated pattern. Between fetal days 45 and 50, tachykinin-rich neuronal clusters increased in frequency and were distributed throughout the rostral caudate nucleus. In contrast to neurons in clusters, neurons in the complementary neuropil expressed tachykinins largely postnatally. Postnatal morphological maturation of tachykinin-containing neurons paralleled the morphogenesis of medium spiny neostriatal cells. In addition, the caudate nucleus and putamen followed different spatiotemporal gradients of tachykinin expression. These results indicate that tachykinins are expressed in neostriatal neurons during the early ontogeny of the neostriatum and may function as trophic factors before synaptogenesis.
Basal forebrain neurons with axon collaterals that project to widely divergent cortical areas were identified using retrograde transport of two labels. A proportion of neurons in the basal forebrain have axon collaterals that project to both anterior (precruciate gyrus) and posterior (marginal and suprasylvian gyri) cortical areas or to medial (precruciate gyrus) and lateral (ectosylvian and anterior suprasylvian gyri) cortical areas. These branched fibers originate from cells located predominantly in the basal nucleus of Meynert. The existence of such neurons suggests that individual basal forebrain cells are capable of influencing widespread neocortical zones in the cat.
The common origins and interrelationships of commissural corticocortical and descending corticostriatal projections were assessed by multiple retrograde labeling of neurons in the precruciate sensorimotor cortex of the cat. The major finding was that some of these neurons had axons that branched at least twice to send collaterals to contralateral cortical sites and bilateral subcortical sites in the caudate nucleus. Regardless of their collateralization, these axons originated mainly from pyramidal neurons of small-medium size located in cortical laminae III-V. A considerable component of the corticocortical and corticostriatal inputs derived from the same neurons. These fibers subserve both intra- and interhemispheric linkages of the sensorimotor cortex with itself and the basal ganglia.
Double-labeling of basal forebrain neurons by retrograde axonal transport demonstrates divergent collateralization among undecussated axonal projections to the neocortex. These branched fibers originate from a considerable complement of large polymorphic cell bodies located mainly in the basal nucleus of Meynert. They terminate in multiple neocortical sites including the precruciate, postcruciate and/or cingulate gyri. This extensive intra- and intergyral axonal branching indicates that neurons in the basal forebrain of the cat have extensive axonal fields innervating adjacent neocortical gyri.
Double-labeling of basal forebrain neurons by retrograde axonal transport of different markers demonstrated afferents shared by the neocortex and neostriatum. A considerable double-labeled complement of neurons located in the globus pallidus (lateral pallidal segment) and the adjacent interdigitating basal nucleus of Meynert (peripallidal region) had branched axonal collaterals projecting to the precruciate, cingulate and prorean gyri as well as to the head of the caudate nucleus.
Developmental patterns of expression and localization of tachykinins in feline neocortex were determined by qualitative immunohistochemical means. Three observations were obtained. (1) By midgestation, tachykinins were progressively accumulated in an infrequent (<1%) population of interneurons (sparse dendritic spines) settled mainly in superficial and deep sites. (2) Tachykinins were in a sparse axonal innervation showing horizontal elaboration in layers I and VI and vertical elaboration within the intervening layers (II-V) of true cortical plate. (3) Tachykinin innervation of the capillary beds arose in conjunction with tachykinin interneurons instead of extending from basal cerebral or meningeal vasculature. These patterns indicate that tachykinin local circuit neurons of feline neocortex are derived, at least in part, from early-generated neocortical preplate neurons that initiate tachykinin expression after they settle into the marginal zone of primitive neocortex. In addition to their roles in peptidergic modulation of synaptic connectivity in neocortex, this innervation may participate in trophic developmental interactions leading to the establishment of neocortical vasculature.