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TO THE EDITORS:Moreno et al.1 describe a patient who developed severe rhabdomyolysis after he was treated with rosuvastatin (ROS) for severe hypercholesterolemia. The first reported lipid panel was performed during severe cholestasis secondary to ischemic liver injury after liver transplantation. Before partial splenic embolization, the total and low-density lipoprotein (LDL) cholesterol levels were 455 and 390 mg/dL, respectively. In the ensuing months, the bilirubin level decreased from 19 to 5.35 mg/dL, and the gamma-glutamyl transpeptidase and alkaline phosphatase levels rose. ROS was instituted 17 days after embolization when the total cholesterol level was 422 mg/dL (the LDL cholesterol level is not reported). The total and LDL cholesterol levels were 411 and 343 mg/dL, respectively, 12 weeks later when rhabdomyolysis occurred, and the ROS treatment was stopped. One month later, the total cholesterol level was 468 mg/dL (the LDL cholesterol level is not reported). Moreno et al. do not mention whether the LDL cholesterol level was calculated or was measured directly. The patient's cholesterol level before he developed cholestatic liver disease is not known. If it was not severely elevated initially, his hypercholesterolemia may have been secondary to a biliary obstruction. In the setting of cholestasis, an uncommon lipoprotein, lipoprotein X (LP-X), is sometimes produced. 2 If the LDL cholesterol level is calculated instead of being measured directly, it appears to be extremely elevated even though LP-X accounts for most of the measured total cholesterol. Hypercholesterolemia caused by LP-X does not respond to statin therapy; the only remedy is resolution of the biliary obstruction or LDL apheresis. 3 The total cholesterol level after 1 month of the ROS treatment was essentially unchanged. With cholestasis still present, it is possible that the statin was ineffective because high levels of LP-X and not LDL were present.

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Fusion of human (diploid) fibroblast monolayers with erythroblasts from 3-day chick embryos resulted in cultures containing on the average 14% heterokaryons and 8% fibroblast homokaryons. When these heterokaryon-containing cultures were labeled with radioactive amino acids during the first 24 h after fusion, the proportion of labeled proteins found in the globin region of analytical polyacrylamide gels showed a 40-fold increase compared with fibroblast homokaryons (0.08% vs. 4% of protein synthesized). Incorporation of radioactivity into globin decreased sharply during the second 24 h. Purified 35S-methionine-labeled globin from heterokaryon cultures gave rise to a tryptic fingerprint containing peptides characteristic of chick embryonic globins as late as 4 days after fusion. While fibroblasts in the fusion culture continue to go through the cell cycle normally, heterokaryons stop cycling almost completely soon after fusion.

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