L:S ratio

(redirected from LS ratio)

L:S ra·ti·o

Farlex Partner Medical Dictionary © Farlex 2012

lecithin:sphingomyelin ratio

(les'i-thin sfing?go-mi'a-lin ra'she-o),

L:S ratio

The ratio of lecithin to sphingomyelin in the amniotic fluid. It is used to assess maturity of the fetal lung. Until about the 34th week of gestation, the lungs produce less lecithin than sphingomyelin. As the fetal lungs begin to mature, they produce more lecithin than sphingomyelin. Delivery before the reversal of the ratio is associated with an increased risk of hyaline membrane disease in the infant. The use of this test enables the obstetrician to determine the best time for elective termination of pregnancy. Other tests commonly used for this purpose include the amniotic lamellar body count, phosphatidylglycerol presence, and the shake test. See: amniocentesis
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
In general, the LS ratio decreased significantly between silking and dough stage.
It is evident from the mean values that there is a decrease in all the three parasympathetic function tests: DBT, LS ratio, and valsalva ratio among the cases as compared to controls although changes are not statistically significant (P > 0.05) between cases and controls.
It is evident from the mean values that there is decrease in all the three parasympathetic function tests: DBT, LS Ratio, and valsalva ratio among the cases as compared to controls, although the changes are not statistically significant (P > 0.05) between cases and controls.
Table 1: Comparison of parasympathetic function tests between cases and controls Parasympathetic Cases (n=50) Control (n=50) P value function tests Mean [+ or -] SD Mean [+ or -] SD DBT 1.61 [+ or -] 0.44 1.76 [+ or -] 0.90 0.30 LS ratio 1.24 [+ or -] 0.28 1.84 [+ or -] 0.52 0.42 Valsalva ratio 1.84 [+ or -] 0.52 1.92 [+ or -] 0.79 0.57 DBT: Deep breathing test, LS ratio: Lying to standing ratio, SD: Standard deviation.
The optimization procedure for the extraction process focusing on the MC (20-80%), ET (30-70[degrees]C), and LS ratio (20-40 mL/g) was devised based on three-factor central composite design, as summarized in Table 1.
The relationship between the independent variables (MC: [X.sub.1]; temperature: [X.sub.2], and LS ratio: [X.sub.3]) and the response variables (TF: [Y.sub.1], TP: [Y.sub.2], and AC: [Y.sub.3]) was demonstrated by the response surface plots.
The TF and TP contents of the extract were more significantly affected by the MC (20-80%), ET (30-70[degrees]C), and LS ratio (20-40 mL/g).
The data in Table 2 demonstrate that when the LS ratio increased from 20: 1 to 40: 1, the TP content also increased by about 5.4% (at [X.sub.1]: 80% and [X.sub.2]: 70[degrees]C).
Figure 1(a) shows the effect of interaction of the MC and the ET on the TF content of the extract at a fixed LS ratio of 30%.
The AC of the extract was significantly affected by the temperature, solvent concentration, and LS ratio (P < 0.05) with three linear effects ([X.sub.1], [X.sub.2], and [X.sub.3]), two quadratic effects ([X.sub.1.sup.2] and [X.sub.2.sup.2]), and three interactive effects ([X.sub.1][X.sub.2], [X.sub.1][X.sub.3], and [X.sub.2][X.sub.3]).
Thus, LS ratio data, which is only available to Springfield, Missouri observations alone, should adequately represent LS ratios for Southwest Missouri.
We tried to select fields with high cellularity, in which the XS/ LS ratio was roughly the same in both myomas of each matched pair.