Lecithin-sphingomyelin ratio

Determination of Lecithin/Sphingomyelin Ratio and Saturated Phosphatidylcholine ... 

Ashwood ER, Tait JF, Foerder CA, Benedetti TJ. Improved fluorescence polarization assay for use in evaluating fetal lung maturity III. Retrospective cEnical evaluation and comparison with the lecithin/sphingomyelin ratio. Clin Chem 1986 32 260-4. 

Dilena BA, Ku F, Doyle I, Whiting MJ. Six alternative methods to the lecithin/sphingomyelin ratio in amniotic fluid for assessing fetal lung maturity. Ann Clin Biochem 1997 34 106-8. 

Gluck L, Kulovich MV. Lecithin/sphingomyelin ratios in amniotic fluid in normal and abnormal pregnancy. Am J Obstet Gynecol 1973 115 539-46. 

Sher G, Statland BE, Knutzen VK. Diagnostic reliability of the lecithin/sphingomyelin ratio assay and the quantitative foam stabiHty index test results of a comparative study. J Reprod Med 1982 27 51-5. 

SpeUacy WN, Buhi WC, Cruz AC, Gelman SR, Kellner KR, Birk SA. Assessment of fetal lung maturity a comparison of the lecithin/sphingomyelin ratio and the tests of optical density at 400 and 650 nm. Am J Obstet Gynecol 1979 134 528-31. 

SpiUman T, Cotton DB, Lynn SC, Bretaudiere JP. Influence of phospholipid saturation on classical thin-layer chromatographic detection methods and its effect on amniotic fluid lecithin/sphingomyelin ratio determinations. Clin Chem 1983 29 250-5. 

Tabsh KM, Brinkman CR 3rd, Bashore RA. Lecithin sphingomyelin ratio in pregnancies complicated by insulin-dependent diabetes mellitus, Obstet Gynecol 1982 59 353-8. 

Wijnberger LD, Huisjes AJ, Voorbij HA, Franx A, Bruinse HW, Mol BW. The accuracy of lamellar body count and lecithin/sphingomyelin ratio in the prediction of neonatal respiratory distress syndrome a meta-analysis. BJOG 2001 108 583-8. 

The test that has gained widest acceptance is the determination of the amniotic fluid lecithin/sphingomyelin ratio, using thin-layer chromatography (TLC). By its nature, this is a time-consuming and labor-intensive test, and an alternative based upon fluorescence depolarization has been proposed and widely adopted. This procedure measures the ratio of surfactant to protein in amniotic fluid. 

IR spectroscopic analysis offers a number of practical advantages that make it a natural fit for high-volume applications of the type epitomized by serum and urine analysis, as well as for labor-intensive tests such as the amniotic fluid lecithin/sphingomyelin ratio. No reagents are required, there is generally no need to dilute very concentrated specimens (as may be required for certain other analytical methods), several analyses are available... 

A technique for the quantitation of coloured bands or spots on chromatograms or electrophoretic strips. Colour intensity can be measured by transmission, when light is allowed to pass through the sample, or by reflectance, when light is reflected from the coloured area. TTie coloured areas are represented as peaks on a chart recorder, and, from this, the area under each peak can be determined. In some instruments, the area under each peak is automatically integrated. Albumin in some laboratories is measured by densitometric techniques. Densitometers can also be used in the measurement of amniotic fluid lecithin sphingomyelin ratios. 

Amniotic fluid palmitic acid can be measured as an indication of fetal lung maturity as an alternative to lecithin-sphingomyelin ratios (q.v.). This is because palmitic acid is a component of the lecithin molecule. High amniotic fluid palmitic acid levels indicate fetal lung maturity and enable early delivery of the infant to be contemplated. Palmitic acid can be estimated by gas-liquid chromatography after hydrolysis of the lecithin to give the free fatty acid. 

Amniotic fluid lecithin-sphingomyelin ratios can be measured to indicate the likelihood of respiratory distress syndrome. 

Sphingomyelins are encountered in another aspect of clinical chemistry, that of lecithin-sphingomyelin ratios (qv). 

Thin-layer chromatography can be used for the separation of drugs, amino acids, sugars and catecholamine metabolites, and for the determination of lecithin-sphingomyelin ratios. 

Dipalmitoylphosphatidylcholine (31) has been quantified in amniotic fluid by FABMS using a d9-labelled standard (97). Such measurements were an alternative to the determination of lecithin-sphingomyelin ratios as a predictive test for lung viability in mid-term and late foetal development. This study is also noteworthy inasmuch as quantification using FABMS has not been widely exemplified. An advantage of the mass spectrometric method is its specificity for the dipalmitoyl derivative (MW 735 daltons). The FAB spectrum also afforded evidence that the mixed palmitoyl oleoyl (MW 761) and tetradecanoyl (MW 707) esters were also present. Homologues were also detected (98) by FABMS of zwitterionic ornithine containing lipids (32) from Thiobacillus thiooxidans and were further discriminated by their CAD spectra. 

---