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Regional Specialization (regional + specialization)

Distribution by Scientific Domains

Life Sciences	60%

Selected Abstracts

Regional specialization of rat quadriceps myosin heavy chain isoforms occurring in distal to proximal parts of middle and deep regions is not mirrored by citrate synthase activity

JOURNAL OF ANATOMY, Issue 1 2007
Tertius Abraham Kohn
Abstract Myosin heavy chain (MHC) isoform content and citrate synthase (CS) activities were measured in the Quadriceps femoris (QF) muscle of 18 female rats. The muscle group was divided into superficial, middle and deep, distal, central and proximal parts. MHC IIb and IIx were more abundant in superficial regions (P < 0.05) with low CS activities compared with deeper parts. The deeper parts expressed all four isoforms (MHC IIb, MHC IIx, MHC IIa and MHC I), with a concomitantly higher CS activity. MHC I, MHC IIa and MHC IIb isoform content varied significantly along the length of the deep regions. Only MHC IIb and CS activity in the proximal middle part correlated (negatively) with each other. This study showed that the QF has regional specialization and that standardization of sampling site is important. Furthermore, CS activity and MHC isoforms are only loosely associated, or not at all. [source]

Regional specialization of the Ganglion cell density in the retina of the Ostrich (Struthio camelus)

ANIMAL SCIENCE JOURNAL, Issue 1 2010
Mohammad L. RAHMAN
ABSTRACT In this study, retinal whole-mount specimens were prepared and stained with 0.1% cresyl violet for the ganglion cell study in the Ostrich (Struthio camelus). The total number, distribution, and size of these cells were determined in different retinal regions. The mean total number of ganglion cells (three retinas) was 1 435 052 with an average density of 652 cells/mm2. The temporo , nasal area of the retina with high cell density were identified with the peak of 7525 cells/mm2 in the central area. The size of most ganglion cells ranged from 113,403 µm2, with smaller cells predominating along the temporo-nasal streak above the optic disc and larger cells comprising more of the peripheral regions. The average thickness of the retina was 196 µm. The central area was the thickest area (268.6 µm), whereas the peripheral area was the thinnest area. Thus, the specialization of ganglion cell densities, their sizes and the thickness of the retina support the notion that the conduction of visual information towards the brain from all regions of the retina is not uniform, and suggests that the temporo , nasal streak is the fine quality area for vision in ostriches. [source]

Local Diversity, Human Creativity, and Technological Innovation

GROWTH AND CHANGE, Issue 3 2001
Pierre Desrochers
The purpose of this paper is to point out some shortcomings of traditional approaches to the study of "knowledge spillovers" and to suggest an alternative based on how knowledge is actually created and exchanged by individuals. Which regional setting is the best incubator of technological change and economic growth? Is this promoted by regional diversity or specialization of economi activity? This study will include economic analyses of geographically localized "dynamic knowledge externalities, Jacob's externalities, or adding new work to old, industrial classification and technology combination, human creativity, and technology combination through human action and imaginative use of resources. Employees add to, or switch their product line; individuals move from one type of production to another; individuals observe a product/process in another setting and incorporate it; individuals possessing different skills and working for different firms collaborate; and urban diversity and resource collaboration are utilized. It is concluded that problems are solved through the combination of previously unrelated things and that promoting regional specialization at the expense of spontaneously evolved local diversity might be a counter-productive policy. [source]

Regional specialization of rat quadriceps myosin heavy chain isoforms occurring in distal to proximal parts of middle and deep regions is not mirrored by citrate synthase activity

Striatal synaptic plasticity: Implications for motor learning and Parkinson's disease

MOVEMENT DISORDERS, Issue 4 2005
Antonio Pisani MD
Abstract Changing the strength of synaptic connections between neurons is widely assumed to be the mechanism by which memory traces are encoded and stored in the central nervous system. Plastic changes appear to follow a regional specialization and underlie the specific type of memory mediated by the brain area in which plasticity occurs. Thus, long-term changes occurring at excitatory corticostriatal synapses should be critically involved in motor learning. Indeed, repetitive stimulation of the corticostriatal pathway can cause either a long-lasting increase or an enduring decrease in synaptic strength, respectively referred to as long-term potentiation (LTP), and long-term depression, both requiring a complex sequence of biochemical events. Once established, LTP can be reversed to control levels by a low-frequency stimulation protocol, an active phenomenon defined "synaptic depotentiation," required to erase redundant information. In the 6-hydroxydopamine rat model of Parkinson's disease (PD), striatal synaptic plasticity has been shown to be impaired, although chronic treatment with levodopa was able to restore it. Of interest, a consistent number of L -dopa,treated animals developed involuntary movements, resembling human dyskinesias. Strikingly, electrophysiological recordings from the dyskinetic group of rats demonstrated a selective impairment of synaptic depotentiation. This survey will provide an overview of plastic changes occurring at striatal synapses. The potential relevance of these findings in the control of motor function and in the pathogenesis both of PD and L -dopa,induced motor complications will be discussed. © 2005 Movement Disorder Society [source]