title: Different apoprotein(a) isoform proportions in serum and carotid plaque.
abstract: BACKGROUND
  Cardio- and/or cerebro-vascular risk are associated with high lipoprotein (a) [Lp(a)] levels and low-molecular-weight (LMW) apo(a) isoforms. Aims of this study were to evaluate the deposition of apo(a) isoforms and apoprotein B (apo B) in atherosclerotic plaque from patients (males and females) who had carotid endarterectomy for severe stenosis, and to identify differences between patients classified by gender and divided according to the stability or instability of their plaques.
  
  
  METHODS
  We determined lipids, apo B and Lp(a) in serum and plaque extracts from 55 males and 25 females. Apo(a) was phenotyped and isoforms were classified by number of kringle IV (KIV) repeats.
  
  
  RESULTS
  Lp(a) levels were higher in female serum and plaque extracts than in male samples, while apo B levels were lower. More Lp(a) than apo B deposition was observed in plaque after normalization for serum levels. Thirty-one different apo(a) isoforms were detected in our patients, with a double band phenotype in 94% of cases. In both sexes, the low/high (L/H) molecular weight apo(a) isoform expression ratio was significantly higher in plaque than in serum. Females with unstable plaques had higher Lp(a) levels in both serum and tissue extracts, and fewer KIV repeats of the principal apo(a) isoform in the serum than the other female group or males.
  
  
  CONCLUSIONS
  In both sexes, the same apo(a) isoforms are found in serum and atherosclerotic plaque, but in different proportions: in plaque, LMW apo(a) is almost always more strongly accumulated than HMW apo(a), irrespective of any combination of apo(a) isoforms in double band phenotypes or Lp(a) serum levels. Moreover, serum and tissue Lp(a) levels were higher in females than in males, and particularly in the group with unstable plaques.
authors.affiliation: Department of Medical and Surgical Sciences, University of Padua, Italy. goretta.baldo@unipd.it
authors.forename: Goretta
authors.initials: G
authors.lastname: Baldo
authors.forename: Silvia
authors.initials: S
authors.lastname: Giunco
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kontothanassis
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Baiocchi
authors.forename: Anna
authors.initials: A
authors.lastname: Valerio
authors.forename: Mauro
authors.initials: M
authors.lastname: Frego
mesh_terms: D000368:Aged; D053241:Apoprotein(a) / Q000097:blood* / Q000737:chemistry / Q000378:metabolism*; D016893:Carotid Stenosis / Q000378:metabolism* / Q000601:surgery; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D018082:Kringles; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood; D017270:Lipoprotein(a) / Q000097:blood / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D012727:Sex Characteristics
chemical_list: D008055:Lipids; D017270:Lipoprotein(a); D020033:Protein Isoforms; D053241:Apoprotein(a)