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Low density lipoproteins (LDL) heterogeneity and intravenous fat in neonates
O Genzel-Boroviczény1, A D'Harlingue, T Forte
1Division of Neonatology, Klinikum Grosshadern of the Ludwig-Maximilians-University, Marchioninistr. 15, Munich D-81377, Germany.
Insights
Neonates receiving intravenous (IV) fat therapy showed diverse LDL subclass profiles, with no significant shifts despite increased triglycerides. This suggests other metabolic factors influence neonatal fat metabolism beyond particle size.
Area of Science:
- Biochemistry
- Neonatal Metabolism
- Lipidology
Background:
- Intravenous (IV) fat emulsions mimic triglyceride-rich lipoproteins but are poorly tolerated by neonates due to low fat metabolism enzyme levels.
- Neonatal intolerance to IV fat necessitates understanding its metabolic effects, particularly on lipoprotein profiles.
Purpose of the Study:
- To investigate the impact of IV fat therapy on low-density lipoprotein (LDL) subclass distribution in neonates.
- To analyze LDL subclass patterns in 20 neonates who could not tolerate enteral feeding.
Main Methods:
- LDL particle size was determined using non-denaturing gradient gel electrophoresis.
- Analysis focused on LDL subclass distribution profiles and peak positions.
Main Results:
- Baseline LDL size distribution showed significant diversity, with three distinct profiles (large, medium, and small LDL peaks) not matching adult patterns (LDL A or B).
- IV fat feeding and enteral nutrition did not alter the LDL peak position, despite increases in plasma triglyceride and apo B concentrations.
- Findings suggest an increase in LDL particle number rather than size during IV fat therapy in neonates.
Conclusions:
- The stable LDL peak position during IV fat therapy, despite rising triglyceride and apo B levels, indicates complex neonatal lipid metabolism.
- Hormonal status and lipid transfer protein activities are likely crucial factors influencing neonatal lipoprotein profiles and warrant further investigation.
Background:
The properties of iv-fat emulsions are similar to those of triglyceride-rich plasma lipoproteins and rapidly hydrolyzed by lipoprotein lipase. Neonates frequently do not tolerate iv-fat because of low levels of the key enzymes for fat metabolism.
Purpose Of The Study:
We examined the effect of iv-fat therapy on LDL subclass distribution of 20 neonates unable to tolerate enteral feeding.
Methods:
Particle size was determined by non-denaturing gradient gel electrophoresis.
Results:
The LDL size distribution profiles at baseline showed unexpected diversity in the position of the major lipoprotein peak with three different profiles identified by peak position; profile I with a major peak of large-sized LDL (26.3-28.2 nm), profile II with a major peak at 25.2-26.7 nm and profile III with a major peak of small-sized particles (24.9-25.6 nm). None of the profiles fit the classical LDL pattern A or B found in adult plasma since the skewness associated with the adult pattern was not present. With iv fat feeding and enteral nutrition, no major shift in peak position was observed, even though plasma triglyceride and apo B concentrations increased suggesting that there was an increased number of LDL particles rather than an increase in the size of particles.
Conclusion:
The constancy of the LDL peak position in the face of increases in plasma triglyceride and apo B concentrations during iv fat and the onset of enteral nutrition in neonates suggests that other metabolic events, such as hormone status and lipid and transfer protein activities need to be considered.