1,774 research outputs found
Measurement of time differences between luminous events Patent
Mechanism for measuring nanosecond time differences between luminous events using streak camer
Fast opening diaphragm Patent
Magnetically opened diaphragm design with camera shutter and expansion tube application
Suspended particulate matter in the Chesapeake Bay entrance and adjacent shelf waters
Approximately 400 samples were collected from the mouth of the Chesapeake Bay for various analyses, including 138 for suspended solids. Characteristics of suspended solids that were analyzed included: total suspended matter; total suspended inorganics, total suspended organics; percent organics; particle size distribution; and presence or absence of 11 of the most prominent particle types
Parkinson's Disease: Clinical Signs and Symptoms, Neural Mechanisms, Positron Emission Tomography, and Therapeutic Interventions
Parkinson's disease is one of the most
frequent neurodegenerative brain diseases. Its
time course is slow and is characterized by
progressive loss of dopaminergic and other
brainstem neurons resulting in malfunctioning of
the cerebral neuronal systems responsible for
motor functions. The clinical signs are slowness
of movement, muscle rigidity and rest-tremor
amongst other features. The cause of the disease
is unknown, but recently involvement of genetic
factors is being researched. Positron emission
tomography (PET) allows in vivo determination
of striatai dopaminergic activity. This has
increased our insight in the pathophysiology of
the disease and permits direct study of disease
progression at a biochemical level and equally to
monitor whether potential neuroprotective interventions
are indeed effective. Thus far no drug
has emerged but promising substances are
currently being studied
A description of the GABAergic neurons and axon terminals in the motor nuclei of the cat thalamus.
The GABA neurons and their processes in the cat motor thalamic nuclei were identified and studied with glutamic acid decarboxylase (GAD) immunocytochemistry at both the light and electron microscopic levels. The three nuclei that comprise the motor thalamus, ventral anterior (VA), ventral medial (VM), and ventral lateral (VL), each displayed a characteristic distribution pattern of GAD-positive structures that was consistent with their afferent and intrinsic neuronal organization. All three thalamic nuclei displayed a population of small, GAD-positive cells the dendrites of which contained synaptic vesicles and participated in complex synaptic arrays such as serial synapses, triads, and glomeruli. Based on their ultrastructural features, these GAD-containing cells were identified as local circuit neurons. In contrast, the larger, GAD-negative cells were presumed to be the thalamocortical projection neurons. The axons of GAD-positive local circuit neurons could not be identified in these preparations. The number of GAD-positive dendrites in the neuropil was different for the three thalamic nuclei. In the VA and VM, the GAD-positive dendrites were numerous and formed symmetric synapses with dendrites of GAD-negative cells, mainly in association with corticothalamic boutons. Within VL, the GAD-containing dendrites were more numerous than in VA and VM and formed synapses at influential locations on presumed thalamocortical projection neurons, such as bases of primary dendrites, and bifurcation sites of primary and secondary dendrites. The VA and anterolateral VM nuclei that receive inhibitory GABAergic afferents from the entopeduncular nucleus and substantia nigra contained the highest concentration of large GAD-positive axon terminals. These boutons contained pleomorphic vesicles and numerous mitochondria and formed symmetric synapses and multiple puncta adherentes with dendrites and somata of presumed thalamocortical projection neurons. The size, ultrastructural features, and distribution of these GAD-positive boutons were similar to those features described for basal ganglia terminals in the motor thalamus of the cat. In addition, similar large-size GAD-positive boutons were observed in the medial VM, which receives basal ganglia afferents exclusively from the substantia nigra. The concentration of these terminals in medial VM along the dendrites of thalamocortical projection neurons was much less than that in VA and anterolateral VM. The VL nucleus which lacks basal ganglia input did not contain any large GAD-positive boutons.(ABSTRACT TRUNCATED AT 400 WORDS
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