Differential changes in transforming growth factor-beta isoform expression during postnatal cardiac growth.

Transforming growth factor-beta (TGF-beta) is synthesised as an inactive precursor protein; this is cleaved to produce the mature peptide and a latency associated protein (LAP), which remains associated with the mature peptide until activation by LAP degradation. Isoform specific antibodies raised against the LAPs for TGF-beta 2 and -beta 3 were used to determine the myocardial levels of LAP (activatable TGF-beta) and full length precursor (inactive TGF-beta) forms during post-natal development in the rat. TGF-beta 2 was present predominantly as the precursor in 2 day old myocardium. There was an age-dependent shift from precursor protein to LAP between 2 and 28 days. A corresponding increase in the level of mature (activatable) TGF-beta 2 was found. TGF-beta 3 was detected in significant quantities only as LAP. However, a four-fold increase in the expression of TGF-beta 3 LAP was observed between 2 and 28 days. The substantial increases in activatable forms of TGF-beta 2 and -beta 3 that occur in myocardium during the first 28 days of life in the rat support a role for these proteins in post-natal cardiac development.

Release of creatine kinase-MB and cardiac specific troponin-I following percutaneous transluminal coronary angioplasty.

Up to 20% of patients undergoing successful coronary angioplasty have been shown to have a mild elevation of creatine kinase-MB (CK-MB). The purpose of this study was to investigate the relationship between clinical and angioplasty procedural variables and circulating markers for cardiac injury. We measured both CK-MB and totally cardiac-specific troponin inhibitory protein (Tn-I) in 22 patients immediately before and at an average time of 10 h 36 min following successful angioplasty. Of these patients 16 had stable angina, six had unstable angina and none had recent myocardial infarction. Four patients had minor complications associated with the procedure (prolonged chest pain, limited coronary artery dissection) but none of these patients had increases in either CK-MB or Tn-I. In two patients there was a mild increase in enzyme-activity assayed CK-MB but none of the 22 patients had significant elevation of mass-assayed CK-MB or cardiac-specific Tn-I. This study supports the view that no significant myocardial damage occurs as a result of successful coronary angioplasty irrespective of the stability of the coronary artery disease. This study confirms the known discrepancies between results obtained by immunoassay and immunoinhibition enzyme assay, due to the false-positive results which can be yielded by the latter technique.