Fluorescent protein-based detection of unconjugated bilirubin in newborn serum.
Increased serum levels of unconjugated bilirubin are associated with the development of brain damage in newborns. In current clinical settings, there are no methods for directly determining serum levels of unconjugated bilirubin. UnaG, a fluorescent protein from Japanese eel muscle that specifically binds to unconjugated bilirubin was used in this study. Linear regression analysis was carried out to compare unconjugated bilirubin levels measured by UnaG and conventional bilirubin oxidase methods. Unconjugated bilirubin levels in the serum of newborns who were untreated or treated with phototherapy were compared. Effects of interfering factors in the serum (conjugated bilirubin, hemoglobin, and lipid) on unconjugated bilirubin concentration measured by the UnaG method were also evaluated. Unconjugated bilirubin levels measured by the UnaG method were highly correlated with those determined by the bilirubin oxidase assay. Unconjugated bilirubin levels determined by bilirubin oxidase and UnaG assays were similar in serum samples containing conjugated bilirubin. The performance of the UnaG assay was unaffected by phototherapy and the presence of serum hemoglobin and lipid emulsion. These results demonstrate the clinical applicability of the UnaG method for direct measurement of unconjugated bilirubin levels in newborn serum.
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Sota
S
Iwatani
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Hajime
H
Nakamura
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Daisuke
D
Kurokawa
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Keiji
K
Yamana
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Kosuke
K
Nishida
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Sachiyo
S
Fukushima
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Tsubasa
T
Koda
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Noriyuki
N
Nishimura
Department of Epidemiology, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Hisahide
H
Nishio
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Kazumoto
K
Iijima
Brain Science Institute, RIKEN, Wako 3510198, Japan.
Atsushi
A
Miyawaki
Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe 6500017, Japan.
Ichiro
I
Morioka
D000818:Animals; D001663:Bilirubin / Q000097:blood*; D001681:Biological Assay / Q000379:methods*; D004524:Eels; D005260:Female; D029941:Fish Proteins / Q000737:chemistry*; D006801:Humans; D007231:Infant, Newborn; D008164:Luminescent Proteins / Q000737:chemistry*; D008297:Male; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry*
D029941:Fish Proteins; D008164:Luminescent Proteins; D044925:Oxidoreductases Acting on CH-CH Group Donors; C042401:bilirubin oxidase; D001663:Bilirubin