Biomedical subjects
Publications and source records attributed to T D White.
Enamel hypoplasia in the South African Plio-Pleistocene fossil hominid sample is examined. The Swartkrans hominids are shown to have a higher incidence of hypoplasia than the Sterkfontein hominids. Within the Swartkrans sample, individuals with hypoplasia of the first upper molar have lower-than-expected ages of death. Possible taphonomic explanations for these observations are discussed.
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Recently discovered Plio-Pleistocene vertebrate assemblages have allowed complete systematic revision of the sub-Saharan African Suidae. New phylogenies are proposed for the 7 genera and 16 species of fossil and extant representatives. Suids are common elements of African Plio-Pleistocene faunas, and their evolutionary trends, particularly in the species Mesochoerus limnetes and Metridiochoerus andrewsi, are of great correlative value. Suid data are employed in a refinement of stratigraphic correlations at Omo Shungura, Olduvai, and east of Lake Turkana (formerly East Rudolf) and in a correlation of East African and South African sites, with important implications for interpretation of hominid evolution. The suid record also bears significantly on questions of theoretical evolutionary biology.
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Although it is only a small ganglion, the geniculate ganglion subserves several different sensory systems with sensory fibers distributed to different parts of the head. The ganglion innervates chemoreceptors and phasic mechanoreceptors on the front of the tongue. In addition, the ganglion supplies mechanoreceptors of the hair follicles on the inner surface of the pinna and deep mechanoreceptors of nasal and buccal cavities. The ganglion also innervates chemoreceptors on the soft palate. No neurophysiological evidence was found for sensory innervation of the facial musculature. In considering neuralgias of geniculate ganglion origin, it is necessary to examine the loci of sensory projections of the ganglion and the possible effects of inflammation on pulse discharge patterns of sensory neurons.
New fossil hominid specimens from the Laetolili fossil locality in Tanzania are described. The material includes mandibles and teeth derived from reliably-dated deposits of Pliocene age. Preliminary descriptions, measurements and illustrations are presented.
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When rat brain synaptosomes were incubated with [3H]noradrenaline for 1 min and then exposed to osmotic shock, only about 20% of the newly accumulated [3H]noradrenaline was released. It would appear that most, but possibly not all of the newly accumulated [3H]noradrenaline is rapidly bound to some particulate cytoplasmic constituent within the synaptosome. [3H]Dopamine and [3H]5-hydroxytryptamine were also rapidly bound within synaptosomes but [3H]glycine and [3H]gamma-aminobutyric acid were not. Reserpinization (5 mg/kg, i.p., 24 h before preparation) only slightly reduced the initial rate of [3H]noradrenaline uptake by synaptosomes. However, when reserpinized synaptosomes were osmotically shocked, most of the newly accumulated radioactivity was released; this radioactivity was identified chromatographically as [3H]noradrenaline. On the basis of the findings with reserpinized preparations, it seems likely that (1) the rapid intrasynaptosomal binding involves synaptic vesicles and (2) the neuronal membrane transport system itself may be capable of driving the uptake of noradrenaline by nerve-terminals. The rapid vesicular binding observed may not be essential for the accumulation of the amine by presynaptic terminals during brief exposures.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.