👤 C Ehmann

Patients with severe hypertriglyceridemia (sHTG) have variable lipoprotein lipase (LPL) activity levels that may influence therapeutic response. This exploratory analysis investigated post-heparin triglyceride lipase and phospholipase activities in three cohorts of patients with sHTG who received evinacumab (angiopoietin-like 3 inhibitor) for 12 or 24 weeks during a phase 2 trial: cohort 1, familial chylomicronemia syndrome with bi-allelic loss-of-function (LOF) LPL pathway mutations; cohort 2, multifactorial chylomicronemia syndrome (MCS) with heterozygous LOF LPL pathway mutations; and cohort 3, MCS without LPL pathway mutations. Post-heparin plasma samples were obtained at baseline and at week 24 (end of the treatment period). Triglyceride lipase activities (LPL and hepatic lipase [HL]) were measured using both a colorimetric and a scintillation assays. Phospholipase activities (HL and endothelial lipase [EL]) were measured using a colorimetric assay. Baseline post-heparin LPL triglyceride lipase activity was lowest in cohort 1; treatment with evinacumab for 12 or 24 weeks did not alter activity at week 24 versus baseline across cohorts using the colorimetric assay. Non-HL triglyceride lipase activity (mostly LPL) assessed using the scintillation assay showed a significant increase in cohort 1 at 24 weeks versus baseline (P = 0.04). Neither HL nor EL phospholipase activities differed among cohorts or changed with evinacumab treatment. High intra- and inter-patient variability in lipase activity was observed with all methods. Post-heparin LPL triglyceride lipase activity was lower in patients with sHTG with bi-allelic LPL pathway mutations and increased in that group with evinacumab. The high variability in lipase activities observed via differing methods supports the need for more robust assays. Show less

A new carboxypeptidase (carboxypeptidase S) was found in a Saccharomyces cerevisiae strain lacking carboxypeptidase Y (D. H. Wolf and U. Weiser, Eur. J. Biochem. 73:553-556, 1977). Mutants devoid of carboxypeptidase S activity were isolated from a mutant strain that was also deficient in carboxypeptidase Y. Four mutants were analyzed in detail and fell into one complementation group. The defect segregated 2:2 in meiotic tetrads. Gene dosage experiments indicated that the mutation might reside in the structural gene of carboxypeptidase S. The absence of both enzymes, carboxypeptidases Y and S, did not affect mitotic growth. Ascopore formation was only slightly affected by the absence of both carboxypeptidases. Protein degradation under conditions of nutrient deprivation and under sporulation conditions showed no obvious alteration in the absence of carboxypeptidases Y and S. When a proteinase B mutation, which led to the absence of proteinase B activity and resulted in the partial reduction of sporulation, was introduced into a mutant lacking both carboxypeptidases, the ability of diploid cells to sporulate was nearly completely lost. Mutants lacking both carboxypeptidases were unable to grow on the dipeptide benzyloxycarbonylglycyl-l-leucine as a sole nitrogen source, which indicates an additional function for carboxypeptidases Y and S in supplying nutrients from exogenous peptides. Catabolite inactivation of fructose-1,6-bisphosphatase, cytoplasmic malate dehydrogenase, and phosphoenolpyruvate carboxykinase and inactivation of nicotin-amide adenine dinucleotide phosphate-dependent, glutamate dehydrogenase, events which have been proposed to involve proteolysis in vivo, were not dependent on the presence of carboxypeptidase Y and S. In a mutant lacking both carboxypeptidases, four new proteolytic enzymes with carboxypeptidase activity were detected. Show less