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Picornavirus-like inclusions in polymyositis--aggregation of glycogen particles of the same size
Abstract:
We studied picornavirus-like inclusions in muscle of a 66-year-old man with chronic polymyositis. Inoculation of a muscle homogenate to suckling mice and VeRo cells failed to detect any virus. After treatment of ultrathin sections with 2% amylase, individual particles that constituted inclusions were digested, as were free glycogen particles in the same section. Particles of the inclusions were stained with periodic acid-thiocarbohydrazide-silver proteinate and alkaline-bismuth, as were glycogen particles. The picornavirus-like inclusions seemed to consist of glycogen particles than form a crystalline arrangement in degenerated muscle fibers.
Insights
Picornavirus-like inclusions in muscle tissue were found to be composed of glycogen particles, not viruses. This finding clarifies the nature of these inclusions in chronic polymyositis.
Area of Science:
- Muscle pathology
- Virology
- Biochemistry
Background:
- Investigated picornavirus-like inclusions in muscle tissue from a patient with chronic polymyositis.
- Standard viral detection methods (inoculation of mice and cell cultures) were unsuccessful.
Observation:
- Ultrathin muscle sections were treated with amylase.
- Inclusions and free glycogen particles were digested by amylase.
- Inclusions and glycogen particles showed similar staining patterns with specific reagents.
Findings:
- Picornavirus-like inclusions are composed of glycogen particles.
- These glycogen particles form crystalline arrangements within degenerated muscle fibers.
- The inclusions are not viral in origin.
Implications:
- Reclassifies the nature of these specific muscle inclusions.
- Suggests a potential role for glycogen metabolism or storage abnormalities in polymyositis.
- Highlights the importance of biochemical analysis in differentiating inclusion bodies.