Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The periodontal ligament has a rich sensory nerve supply which serves as a sensory apparatus in addition to tooth support. The periodontal ligament contains nociceptors and low-threshold mechanoreceptors. Stimuli applied to teeth evoke various oral reflexes, which make smooth mastication possible via the periodontal mechanoreceptors. Recent morphological and physiological studies have revealed that Ruffini endings, categorized as low-threshold slowly adapting type II (SA II), are essential mechanoreceptors in the periodontal ligament. The periodontal Ruffini endings are ultrastructurally characterized by expanded axon terminals filled with a number of mitochondria and terminal or lamellar Schwann cells. The axon terminals of the periodontal Ruffini endings have finger-like projections, i.e. axonal spines, extending into the surrounding tissue to detect the deformation of collagen fibers. As histochemical marker enzymes for the periodontal Ruffini endings, the axon terminals and terminal Schwann cells are reactive for cytochrome oxidase activity and both acid phosphatase activity and non-specific cholinesterase activity, respectively. Many experimental studies also have revealed that periodontal Ruffini endings have high potential for neuroplasticity, confirmed by intense immunoreactivity for p75-NGFR and GAP-43. Mechanical stimuli due to tooth eruption and occlusion might be a prerequisite for the differentiation and maturation of the periodontal Ruffini endings. Further investigations are needed for clarifying the involvement of growth factors and the molecular mechanism of the development and regeneration processes of the Ruffini endings.
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PMID:[Morphological basis on periodontal Ruffini endings]. 961 78

The periodontal ligament receives a rich sensory nerve supply and contains many nociceptors and mechanoreceptors. Although its various kinds of mechanoreceptors have been reported in the past, only recently have studies revealed that the Ruffini endings--categorized as low-threshold, slowly adapting, type II mechanoreceptors--are the primary mechanoreceptors in the periodontal ligament. The periodontal Ruffini endings display dendritic ramifications with expanded terminal buttons and, furthermore, are ultrastructurally characterized by expanded axon terminals filled with many mitochondria and by an association with terminal or lamellar Schwann cells. The axon terminals of the periodontal Ruffini endings have finger-like projections called axonal spines or microspikes, which extend into the surrounding tissue to detect the deformation of collagen fibers. The functional basis of the periodontal Ruffini endings has been analyzed by histochemical techniques. Histochemically, the axon terminals are reactive for cytochrome oxidase activity, and the terminal Schwann cells have both non-specific cholinesterase and acid phosphatase activity. On the other hand, many investigations have suggested that the Ruffini endings have a high potential for neuroplasticity. For example, immunoreactivity for p75-NGFR (low-affinity nerve growth factor receptor) and GAP-43 (growth-associated protein-43), both of which play important roles in nerve regeneration/development processes, have been reported in the periodontal Ruffini endings, even in adult animals (though these proteins are usually repressed or down-regulated in mature neurons). Furthermore, in experimental studies on nerve injury to the inferior alveolar nerve, the degeneration of Ruffini endings takes place immediately after nerve injury, with regeneration beginning from 3 to 5 days later, and the distribution and terminal morphology returning to almost normal at around 14 days. During regeneration, some regenerating Ruffini endings expressed neuropeptide Y, which is rarely observed in normal animals. On the other hand, the periodontal Ruffini endings show stage-specific configurations which are closely related to tooth eruption and the addition of occlusal forces to the tooth during postnatal development, suggesting that mechanical stimuli due to tooth eruption and occlusion are a prerequisite for the differentiation and maturation of the periodontal Ruffini endings. Further investigations are needed to clarify the involvement of growth factors in the molecular mechanisms of the development and regeneration processes of the Ruffini endings.
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PMID:The Ruffini ending as the primary mechanoreceptor in the periodontal ligament: its morphology, cytochemical features, regeneration, and development. 1075 11