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Ultrastructure of voluntary muscle in childhood malnutrition
1Department of Pathology, University of the West Indies, Kingston, Jamaica.
Abstract:
This paper is part of a study on the electron microscopy of protein-energy malnutrition, using a rapid autopsy protocol. Samples of voluntary muscle, obtained from eight children dying of severe oedematous malnutrition, were fixed in glutaraldehyde within 75 minutes of death. Atrophy of myofibres, increased prominence of satellite cells, and segmental necrobiosis were seen by light microscopy. Electron microscopy showed variable depletion of myofibrils. In the most severe case, there was focal absence of myofibrils, also disorganized Z lines, and absent M bands. Residual atrophic myofibrils measured less than 0.1 micron in width. Other specimens showed sarcomere disorganization, mitochondrial swelling, glycogen depletion, sarcoplasmic oedema, and focal contractions of sarcomeres. Though non-specific, rigor may be accelerated by free radical damage, calcium release into the cytosol, and low supplies of high-energy phosphates. These conditions may exist in severe malnutrition, complicated by terminal infection and metabolic disturbances.
Insights
Severe malnutrition causes muscle fiber atrophy and myofibril damage, observed via electron microscopy. Rapid autopsy revealed cellular changes, indicating significant muscle breakdown in affected children.
Area of Science:
- Cellular Biology
- Pathology
- Nutritional Science
Background:
- Protein-energy malnutrition (PEM) significantly impacts cellular structures.
- Understanding the ultrastructural changes in muscle is crucial for diagnosing and treating severe malnutrition.
Purpose of the Study:
- To investigate the ultrastructural changes in skeletal muscle of children with severe oedematous malnutrition.
- To correlate light and electron microscopy findings with the severity of malnutrition.
Main Methods:
- Utilized a rapid autopsy protocol, fixing muscle samples within 75 minutes of death.
- Employed both light microscopy and electron microscopy for detailed cellular analysis.
- Examined voluntary muscle tissue from eight children diagnosed with severe oedematous malnutrition.
Main Results:
- Observed myofiber atrophy, increased satellite cells, and segmental necrobiosis via light microscopy.
- Electron microscopy revealed variable myofibril depletion, disorganized Z lines, and absent M bands in severe cases.
- Identified mitochondrial swelling, glycogen depletion, sarcoplasmic edema, and sarcomere disorganization.
Conclusions:
- Severe malnutrition leads to significant myofibrillar damage and sarcomere disorganization.
- Ultrastructural muscle changes are consistent with cellular stress, including potential free radical damage and energy depletion.
- Findings highlight the profound impact of malnutrition on muscle tissue integrity.