title: Immunohistochemical expression of cell differentiation and growth in neonate cardiomyocytes.
abstract: BACKGROUND
  The cardiac alterations during the fetal heart transition to extrauterine life have been explored by several animal studies and the cell mechanisms responsible for these modifications are not well documented in humans.
  
  
  OBJECTIVE
  To evaluate the mechanism of cell differentiation into cardiomyocytes that occur in the first days of life, through immunohistochemical analysis of proteins involved in proliferation and muscle contraction processes, in samples of human neonate myocardium.
  
  
  METHODS
  Cross-sectional study of paraffin-sample sections of myocardium from an autopsy database of human neonates, divided into two sample groups: full-term neonates who died after a maximum of two days of life (NEO1) with 10 cases, and full-term infants who died between 3 and 10 days of life (NEO2) with 14 cases, in order to follow a temporal line that would contemplate the transition from fetal circulation to extrauterine life. The samples were studied in tissue microarray and the antibodies used were Ki67, PCNA, PTEN, Bcl2 (proliferation), HHF35 and sarcomeric actin (contractile proteins).
  
  
  RESULTS
  Difference was observed regarding Ki67, p = 0.02; HHF35, p <0.01 and sarcomeric actin, p = 0.02, with Ki67 expression being higher in NEO1 group, whereas HHF35 and sarcomeric actin expression was higher in the NEO2 group.
  
  
  CONCLUSIONS
  The results suggest that cardiomyocytes have a proliferation characteristic (Ki67) in NEO1 which, following a temporal line, will be replaced by a differentiation characteristic (HHF35 and sarcomeric actin) in NEO2.
authors.affiliation: Pontifícia Universidade Católica do Paraná - PUC-PR1, Brazil.
authors.forename: Tarcísio Fulgêncio Alves da
authors.initials: TF
authors.lastname: Silva
authors.forename: Greyce Kelly de
authors.initials: GK
authors.lastname: Souza
authors.forename: Mona Adalgisa
authors.initials: MA
authors.lastname: Simões
authors.forename: Francisco Cesar
authors.initials: FC
authors.lastname: Pabis
authors.forename: Luciade
authors.initials: L
authors.lastname: Noronha
mesh_terms: D000199:Actins / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001344:Autopsy; D002454:Cell Differentiation / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005326:Fetal Proteins / Q000032:analysis*; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007231:Infant, Newborn; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000737:chemistry / Q000166:cytology*; D012518:Sarcomeres / Q000502:physiology
chemical_list: D000199:Actins; D000911:Antibodies, Monoclonal; D005326:Fetal Proteins; D019394:Ki-67 Antigen