الفهرس 
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Abstract
Respiratory-distress syndrome in the newborn is a major cause of neonatal mortality and morbidity. Prematurity is the most-important risk factor for RDS. The main cause of RDS is a deficiency of pulmonary surfactant.
Fetal alveolar type II epithelial cells utilize lipid substrates to synthesize DPPC, the major surfactant lipid that lowers surface tension at the alveolar air-fluid interface. Potential sources of fetal lipids include transport of free fatty acids from the maternal circulation or de novo synthesis within the fetus or placenta.
Apolipoproteins are different types of proteins that bind hydrophobic lipids in the blood and help solubilize them Together with phospholipids; apolipoproteins form lipoprotein particles into which different lipids can be packed.
There are two major types of apolipoproteins: non-exchangeable and exchangeable. Apolipoprotein B (apoB) is non-exchangeable and anchored in the lipoprotein particle whereas apolipoproteins A, E, D, J and H are exchangeable and can be transferred between different lipoprotein particles.
There are two types of apolipoprotein A (A1, AII). Apolipoprotein A1 is the major protein component of high density lipoprotein (HDL) in the plasma. Chylomicron secreted from intestinal entrocyte also contains apo A1, but is quickly transferred to HDL in the blood stream.
Preterm infant with RDS have been reported to have significantly higher levels of cord serum apolipoprotein A1 compared to the levels of preterm and normal newborns without RDS. The aim of this study is to detect the efficacy of Apolipoprotein A1 as a marker for early detection of RDS in preterm infant.
Our study was conducted on 90 neonates: 30 preterm with RDS, their gestational ages ranging from 28 to 36 weeks, birth weights ranging from(850 to 2400 g),30 preterm neonates without RDS, their gestational ages ranging from 31 to 36 weeks, birth weights ranging from (1500 to 2400 g) and 30 full term healthy neonate were enrolled in this study as a control group.
Each neonate was subjected to:
1) Full history taking
2) Physical examination (included General examination, chest examination).
3) Laboratory investigations (Complete blood count, arterial blood gases, blood chemistry(Na, K, liver functions, kidney functions, blood glucose and serum bilirubin) and chest X ray.
4) Specific investigation(Apolipoprotein A1 (apo Lp-A1) obtained from cord blood immediately after birth).
Our study showed significant difference between the patients groups as regard to the birth weight and the gestational age but no significant difference as regard to sex and mode of delivery was found.
Regarding the maternal risk factors our study showed that premature rupture of membrane (PROM) was the highest maternal risk factor among the patients group followed by placenta previa, hypertension. While twins were the highest neonatal risk factor among the patients group.Our study showed that the highly presented complications among the patient group were sepsis followed by DIC and sepsis, anemia, pulmonary hemorrhage.
Our study showed that there were significant difference between the studied groups regarding their CBC results as HCT value, TLC and platelets count, but there were no significant difference regarding their hemoglobin and RBCs count. Also CRP levels showed highly significant increase in group 1a and group 1b compared to control group.
Our study showed that there was highly significant difference between the studied groups regarding the arterial blood gases being more acidic in group 1A.
Our study showed that there was significant increase level of Apo A1in the group1a with mean (96.86±13.41) than group 1b with mean (75.75 ± 5.14) compared to group2with mean (70.22 ± 4.50).
Using receiver operating characteristic (ROC) curve of Apo A1to calculate the best cutoff value of APO A1 as a marker for RDS was (>84.90) mg/ml with diagnostic 83% Sensitivity and 63% Specificity While the best cutoff value of Apo A1 between Neonates without RDS and controls was (>79.05) with 77% Sensitivity and 80% Specificity.
Our study showed that there was significant difference between the studied groups regarding the level of urea, creatinine, AST and ALT results but no significant difference as regards Na, K were found.
There was significant-ve correlation between APO A1 and weight of neonate. Also, there was significant correlation between the level of APO A1 and poor moro reflex and characteristic respiratory distress signs (tachypnea, grunting, retraction, cyanosis Our results showed that APO A1 is used for early detection of RDS in preterm infant with RDS. We recommend use of Apo A1, and other markers in diagnosis of neonatal RDS.