Biomedical subjects

C Umstetter

Publications and source records attributed to C Umstetter.

3 recordsLinked to original sources

PubMed1985

Intestinal triglycerides are derived from both endogenous and exogenous sources.

Although studies have indicated that the small intestine is capable of utilizing endogenous substrates for triglyceride synthesis in the absence of dietary lipid, the importance of the endogenous contribution to total intestinal triglyceride production during absorption has not yet been defined. In this study we have examined the quantitative contribution of endogenous triglyceride production during different luminal lipid loads. By use of a mesenteric lymph fistula rat model with total parenteral nutritional support, mesenteric lymphatic triglyceride transport was investigated. Our results indicate that, during absorption, a substantial fraction (greater than 50%) of total triglyceride is derived from endogenous sources. Increased luminal fatty acid loads lead to an increase in both endogenous and exogenous triglyceride production. Incorporation of luminally infused oleic acid into triglyceride carried by chylomicrons is dependent on the luminal fatty acid load, while incorporation of oleic acid into very low-density lipoprotein (VLDL) triglyceride is saturable. We conclude that both chylomicron and VLDL are involved in transporting triglyceride derived from both endogenous and exogenous sources. The different patterns in the partition of endogenous and exogenous triglyceride into chylomicrons and VLDL suggest that these two lipid-carrying lipoproteins are probably packaged differently in the small intestine.

Animals↗

PubMed1980

Apical distribution of fatty acid esterification capacity along the villus-crypt unit of rat jejunum.

Distribution of fatty acid esterification capacity along the structure of the villus-crypt unit was studied in both in vivo perfused an in vitro incubated rat jejunum. Using a cryostat sectioning technique, the intestine was sectioned transversely at 6 micron thickness, from the tip of the villus to the crypt. Morphology and sucrase activity were used as markers to define the location along the villus-crypt unit. Fatty acid esterification capacity was found to be more apically concentrated in both in vivo and in vitro preparations. The apical distribution of fatty acid esterification capacity is a reflection of the distribution patterns of lipid esterifying enzyme activity along the villus-crypt units.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗

PubMed1979

Development of fatty acid esterification mechanisms in rat small intestine.

Fatty acid esterification was measured in fetal jejunal and ileal isografts implanted under the kidney capsules of adult host rats and compared to the age-controlled intestine grown in situ. Studies were conducted on the 21st, 35th, 49th, and 63rd postconceptional days, corresponding to prenatal, suckling, weaning, and weaned rats. Substantial fatty acid esterification activity was found in prenatal jejunum but not in ileum. A proximal-distal gradient of fatty acid esterification was observed in all groups grown in situ, but not in isografts. The monoglyceride pathway (MG-P) accounted for about one-third of total fatty acid esterification (TFAE) in jejunum grown in situ and remained constant through the study. In the ileum, MG-P was the major esterification pathway during the first 4 postnatal weeks, but decreased progressively after weaning to become insignificant in adult rats. TFAE fell in the jejunal isografts, whereas it increased in the ileum. MG-P remained as the major pathway in the implanted jejunum and ileum. Our studies suggest that luminal contents are probably the most important modulator for the development and maintenance of intestinal fatty acid esterification, and "fetal programming" manifested by changes in fatty acid esterification mechanisms in the isografts is less important.

Animals↗