title: Angiotensin-converting enzyme gene polymorphism and respiratory muscle function in infants.
abstract: OBJECTIVE
  Angiotensin-converting enzyme (ACE) gene contains a polymorphism consisting of either the presence (I) or absence (D) of a 287-bp fragment. Recent studies have suggested that the I-allele may be associated with superior exercise endurance; respiratory muscle function may be similarly influenced. The pressure-time index of inspiratory muscles (PTImus) is a measure of the load-capacity ratio of the inspiratory muscles. The objective of this study was to determine whether infants homozygous for the I-allele have lower PTImus compared to infants homozygous for the D-allele or heterozygous I/D.
  
  
  METHODS
  One hundred thirty-two infants were studied. ACE genotyping was performed by polymerase chain reaction amplification, using DNA from peripheral blood. PTImus was calculated as (Pi(mean)/Pi(max)) × (T(i)/T(tot)), where Pi(mean) was the mean inspiratory pressure estimated from airway pressure, generated 100 ms after an occlusion (P(0.1)), Pi(max) was the maximum inspiratory pressure and T(i)/T(tot) was the ratio of the inspiratory time to the total respiratory cycle time. Pi(max) was the largest pressure generated during brief airway occlusions performed at the end of a spontaneous crying effort.
  
  
  RESULTS
  Infants with I/I genotype had significantly lower PTImus than infants with either D/D or I/D genotypes (P = 0.000007). ACE genotype was significantly related (P = 0.005) to PTImus measurements, independent of other factors that may affect respiratory muscle function.
  
  
  CONCLUSIONS
  These results suggest that an association of ACE genotypes with PTImus measurements may exist in infants.
authors.affiliation: Neonatal Intensive Care Unit, Department of Pediatrics, University of Patras Medical School, Rio, Patras, Greece. gdimitriou@med.upatras.gr
authors.forename: Gabriel
authors.initials: G
authors.lastname: Dimitriou
authors.forename: Despina
authors.initials: D
authors.lastname: Papakonstantinou
authors.forename: Eleana F
authors.initials: EF
authors.lastname: Stavrou
authors.forename: Sotirios
authors.initials: S
authors.lastname: Tzifas
authors.forename: Aggeliki
authors.initials: A
authors.lastname: Vervenioti
authors.forename: Aglaia
authors.initials: A
authors.lastname: Athanassiadou
authors.forename: Stefanos
authors.initials: S
authors.lastname: Mantagos
mesh_terms: D005260:Female; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D001239:Inhalation / Q000502:physiology; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology*
chemical_list: D007703:Peptidyl-Dipeptidase A