Urogastrone and Lactose Concentrations in Precolostrum, Colostrum, and Milk

Abstract

SummaryThe concentration of urogastrone (URO) and lactose was measured in breast secretions from four women. URO levels were high in precolostrum and fell markedly around the time of parturition to relatively constant low levels in mature milk. When milk samples were fractionated on a Biogel PI0 column, the major peak of immunoreactivity occurred at the point at which pure URO eluted.There was good correspondence between the fall in URO levels at birth and the increase in lactose levels, suggesting that the decrease in URO was a dilution effect as the osmotic influence of lactose increased. Abbreviations EGF, epidermal growth factor RIA, radioimmunoassay URO, urogastroneHuman milk is a food source specifically tailored to the needs of the newborn infant and fulfis all the child's nutritional requirements for the first 4-6 months of life and up to three-quarters of his needs from 6-12 months of age (33). For a great many years cow's milk has substituted for human milk in feeding the newborn infant. With this use came an interest in comparing the composition of the two milks in an attempt to justify the continued use of this substitution (for reviews see 15 and 32); however, it is now commonly accepted that human milk is of greater nutritional value in feeding the newborn infant than cow's milk (1, 21). Furthermore, milk does not just f u l f i a nutritional role, but contains antibody molecules and other antimicrobial factors that are involved in the transfer of passive immunity (27, 28), and hormones and growth factors of unknown function (3,23,31). The concentration of hormones and growth factors in milk varies between species, presumably reflecting the varying needs of the neonate. Although we do not understand the role these molecules play in the neonate, it becomes important to compare their levels throughout lactation.In the study to be reported here we monitored the concentration of URO (the human equivalent of mouse EGF) in precolostrum, colostrum, and mature milk, from human donors. MATERIALS AND METHODSMilk samples. Milk was obtained from five individuals at various stages of pregnancy and lactation. Samples from four of the volunteers (CK, AR, JL, and KD) were supplied during antenatal and postnatal periods and were assayed after up to 12 months in storage at -40°C. The 5th donor (CL) only provided mature milk samples, and these were assayed within 4-8 wk of collection.Milk was manually expressed into the sterile universal containers provided, and stored in a domestic freezer compartment until they were transferred to storage at -40°C in the laboratory.Samples were centrifuged at 9000 x g in a Microfuge (Beckman RIIC Ltd.) and the aqueous phase withdrawn from below the floating lipid layer and assayed for URO activity.For the purposes of this study, we considered all milk produced before delivery as being precolostrum, milk produced during the first 48 h after delivery as colostrum, and milk produced after the first 48 h postpartum as mature milk. Donors CK, AR, and JL who were hypersecretory produced ...

Biochemical study of cyst fluid in human breast cystic disease: a review

“…High concentrations of EGF are present in human colostrum and milk [83][84][85] and in nipple aspirates [86]. The concentration of EGF in plasma is extremely low [87,88] but increases during pregnancy [89], suggesting that EGF may have a role in breast differentiation.…”

Apolipoprotein Synthesis in Newborn Piglet Intestinal Explants

“…Furthermore, it is not certain at what level EGF may exert some of these effects, because some effects noted in the intact animal are not found in intestinal culture studies, suggesting that the intestinal EGF effects may be part of a systemic response to EGF (45). In the present study, EGF was added to the explant medium at a concentration that approximates the upper limit of the concentration in human colostrum (49). At this concentration, EGF significantly stimulated total protein synthesis in the piglet jejunal explants.…”

The Concentration of Epidermal Growth Factor in Japanese Mother's Milk.

“…Many researchers have measured the concentration of EGF in human milk, bovine milk and bovine milk-based infant formulae (11)(12)(13)(14)(15)(16)(17)(18). Human milk contains a high concentration of EGF in comparison with other tissues or body fluids.…”

“…Human milk contains a high concentration of EGF in comparison with other tissues or body fluids. However the concentration of EGF in human milk varied among the various studies because of differences in measuring methods: radioreceptor assay (RRA, 15,16,17,18,20) and radioimmune assay (RIA,11,12,14). Even by RRA, Iacoptta et al reported that when placental plasma membrane is used for RRA the concentration of EGF might be overestimated, whereas intact A431 cells are used this does not happen.…”

“…Several researchers have determined the content of EGF in human milk, however, the results varied greatly (11)(12)(13)(14)(15)(16)(17)(18). In these studies, a small number of samples was investigated.…”