Human skeletal muscle in viral and mycoplasma infections: ultrastructural morphometry and its correlations to enzyme activities.

The quantitative effects of acute viral and mycoplasma infections on subcellular elements of skeletal muscle have been investigated in seven hospitalized patients, aged 20-42 years, and the findings are correlated to the activities of glyceraldehyde-3-phosphate (triosephosphate) dehydrogenase (TPD), lactate dehydrogenase (LDH), citrate synthetase (CS), and cytochrome c oxidase (cytox). Comparisons are made with five healthy men, aged 22-29 years, who were confined to bed for 7 days, being the mean period of confinement to bed in the patients. The muscle samples were taken from the thigh. In both patients and controls a decrease of the volume fraction of the myofibrillar compartment was observed in the acute phase of the illness when compared to 4 months afterwards. It was inversely related to the volume fraction of the sarcoplasmic space. The volume fraction of unspecified vacuols was increased in the acute phase and was greater than that of the control subjects confined to bed. The fraction of sarcoplasmic space and that of vacuols correlated negatively to the activity of CS. The activity of cytox correlated to the volume fraction of mitochondria. No correlations were found for TPD or LDH.