No abstract

A supraphysiologic (>95th percentile) rise in plasma lipids in pregnancy may serve as a marker for "prelipemia" in the same way that gestational diabetes is a marker for prediabetes. To qualify as prelipemic, subjects with an abnormal lipid rise antepartum must return to normal postpartum but may have other identifying characteristics. This paper describes the antepartum-postpartum changes of lipoprotein lipids and apoproteins at 34 to 38 weeks of gestation and 6 and 20 weeks postpartum in 23 subjects with physiologic and six subjects with supraphysiologic plasma lipid increases during pregnancy. These results are compared to measurements in 23 nonpregnant controls matched for weight, age, and race. In subjects with a physiologic antepartum lipid rise, postpartum total triglyceride and very low density lipoprotein (VLDL) lipids (cholesterol and triglyceride) and apo B returned to baseline within 6 weeks. 12 With respect to glucose homeostasis, it is well known that some women manifest overt diabetes under the stress of pregnancy but revert to normal after delivery. The deterioration of glucose homeo- Received August 17, 1983; revision accepted March 14, 1984. stasis in pregnancy, known as gestational diabet e s , 1 3 4 is considered to be a form of prediabetes because it predicts later progression to overt diabetes with a high degree of accuracy. 4 It is not yet known if a similar deterioration of lipid homeostasis occurs in pregnancy, reverts to normal postpartum, and predicts the appearance of overt nongestational hyperlipidemia years later. Such a condition might be termed "prelipemia" and if identified would provide an important tool to study the natural history of hyperlipidemia from its earliest stages. This paper presents information to support the hypothesis that prelipemia is identified by a supraphysiologic lipid rise in pregnancy. The postpartum return of plasma lipids and lipoproteins to baseline is described in normal subjects. These results are compared to women with supraphysiologic elevations in triglyceride or cholesterol in pregnancy but with de-407 by guest on May 11, 2018 http://atvb.ahajournals.org/ Downloaded from

Sera from young laying chickens, found to be hypertriglyceridemic by serum lipid and lipoprotein analyses, were fractionated by ultracentrifugation into very low ( d < 1.006 g/mL) and low density ( d 1.006-1.063 and 1.024-1.045 g/mL) lipoproteins (VLDL and LDL). The purity of these lipoprotein fractions was evaluated by electrophoretic, immunological, and electron microscopic techniques; their chemical and physical properties were subsequently determined and compared with those of the corresponding human fractions. While an overall resemblance was evident between each chicken fraction and its human counterpart, minor differences were detected in surface charge, chemical composition, and particle size. Both chicken VLDL and LDL exhibited lo\v surface charge upon electrophoresis; the triglyceride content and particle size of the chicken LDL fractions were greater than those of the corresponding human preparations. Immunological studies revealed a partial identity between the VLDL and between the LDL of chicken and man; quantitative microprecipitation showed the cross-reactivity of chicken and human LDL to amount to about 10%. The chicken lipoproteins possessed a common antigenic determinant and reacted strongly to an antiserum to human apolipoprotein B. The presence of an apolipoprotein B like component in chicken VLDL and LDL was confirmed by sodium dodecyl sulfate-

Summary ― The effects of triglycerides (TG) from tallow (1.21 and 2.13 g TG/kg of body weight (BW) per meal, diets R and B respectively) and from tallow plus cream (2.50 g TG/kg of BW per meal, diet L) with or without L -methionine (2.6 g/kg dry matter) on hepatic apparent secretion of very low density lipoproteins (VLDL) were investigated in 3 groups of 4 preruminant calves fitted with chronic catheters and with electromagnetic blood-flow probes implanted in their hepatic vessels. Increasing TG concentrations stimulated the apparent VLDL secretion by the liver (1.02, -0.36 and -1.51 mg VLDL mass/min per kg of BW in diets L, B and R, respectively). L -Methionine increased this secretion when associated with the lipid-restricted (diet R; 0.25 and -1.51 mg VLDL/min per kg of BW) and basal (diet B; 0.35 and -0.36 mg VLDL/min per kg of BW) diets (non-significant). However, the VLDL apparent secretion decreased with the lipid-enriched diet (diet L), which suggests an insufficient dose of Lmethionine compared with the level of TG intake, and a possible competition between liver and intestine for utilization of L -methionine for the synthesis of TG-rich lipoproteins.

Qualitative, quantitative, and comparative aspects of the serum lipoprotein profile in the Common marmoset (Callithrix jacchus), a New World primate, are described. Density gradient ultracentrifugation was used to evaluate lipoprotein distribution and to establish criteria for isolation of discrete molecular fractions. The major lipoprotein classes banded isopycnically on the gradient with the following hydrated densities: VLDL, d less than 1.017 g/mL; LDL, d = 1.027--1.055 g/mL; HDL fraction I, d = 1.070--1.127 g/mL; and HDL fraction II, d = 1.127--1.156 g/mL. Electrophoretic, immunological, and electron microscopic analyses attested to the purity of these fractions: the characteristics of each were assessed by chemical analysis, electron microscopy, immunological techniques, and polyacrylamide gel electrophoresis of their protein moieties. Marmoset VLDL and LDL were closely akin to those of man in size and chemical composition, although the former were richer in triglyceride; electrophoretic and immunological data showed the major protein component of VLDL and LDL to be a counterpart to human apo-B. The two HDL subfractions, i.e., HDL-I and HDL-II, corresponded in size and chemical composition to human HDL2 and HDL3, respectively, although slight differences in neutral lipid content were detected. By immunological and electrophoretic criteria, the major apolipoprotein of marmoset HDL was analogous to human apo-AI. In contrast, marked dissimilarities were evident in the complements of low molecular weight, tetramethylurea-soluble polypeptides of marmoset and human lipoproteins. Quantitatively, the human and marmoset lipoprotein profiles were not dissimilar, although HDL was the major class (approximately 50%); in fasting animals, serum concentrations of VLDL, LDL, and HDL were 50--90, 170--280, and 338--408 mg/dL, respectively. C. jacchus was distinct from man in displaying a greater proportion of its total HDL in the less dense (HDL-II) subfraction (marmoset HDL-I/HDL-II = approximately 4:1; human HDL2/HDL3 = approximately 1:3). These data indicate that, as an experimental animal for lipoprotein research, the Common marmoset combines the advantages of ready availability and maintenance with a serum lipoprotein profile which resembles, in many qualitative and quantitative aspects, that found in man.