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BackgroundTo determine the effect of human milk, maternal and donor, on in-hospital growth of very low birthweight (VLBW) infants. We performed a retrospective cohort study comparing in-hospital growth in VLBW infants by proportion of human milk diet, including subgroup analysis by maternal or donor milk type. Primary outcome was change in weight z-score from birth to hospital discharge.MethodsRetrospective cohort study.Results171 infants with median gestational age 27 weeks (IQR 25.4, 28.9) and median birthweight 899 g (IQR 724, 1064) were included. 97% of infants received human milk, 51% received > 75% of all enteral intake as human milk. 16% of infants were small-for-gestational age (SGA, < 10th percentile) at birth, and 34% of infants were SGA at discharge. Infants fed >75% human milk had a greater negative change in weight z-score from birth to discharge compared to infants receiving < 75% (−0.6 vs, -0.4, p = 0.03). Protein and caloric supplementation beyond standard human milk fortifier was related to human milk intake (p = 0.04). Among infants receiving > 75% human milk, there was no significant difference in change in weight z-score by milk type (donor −0.84, maternal −0.56, mixed −0.45, p = 0.54). Infants receiving >75% donor milk had higher rates of SGA status at discharge than those fed maternal or mixed milk (56% vs. 35% (maternal), 21% (mixed), p = 0.08).ConclusionsVLBW infants can grow appropriately when fed predominantly fortified human milk. However, VLBW infants fed >75% human milk are at greater risk of poor growth than those fed less human milk. This risk may be highest in those fed predominantly donor human milk.

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In maize, two paralogous genes, Sh1 and Sus1, encode two biochemically similar isozymes of sucrose synthase, SS1 and SS2, respectively. Previous studies have attributed the mild starch deficiency of the shrunken1 (sh1) endosperm to the loss of the SS1 isozyme in the mutant. Here we describe the first mutation in the sucrose synthase1 (Sus1) gene, sus1-1, and the isolation of a double recessive genotype, sh1 sus1-1. Combined data from diverse studies, including Northern and Western analyses, RT-PCR and genomic PCR, cloning and sequencing data for the 3' region, show that the mutant sus1-1 gene has a complex pattern of expression, albeit at much reduced levels as compared to the Sus1 gene. Endosperm sucrose synthase activity in sh1 sus1-1 was barely 0.5% of the total activity in the Sh1 Sus1 genotype. Significantly, comparative analyses of Sh1 Sus1, sh1 Sus1 and sh1 sus1-1 genotypes have, for the first time, allowed us to dissect the relative contributions of each isozyme to endosperm development. Starch contents in endosperm of the three related genotypes were 100, 78 and 53%, respectively. Anatomical analyses, which confirmed the previously described early cell degeneration phenotype unique to the sh1 Sus1 endosperm, revealed no detectable difference between the two sh1 genotypes. We conclude that the SS1 isozyme plays the dominant role in providing the substrate for cellulose biosynthesis, whereas the SS2 protein is needed mainly for generating precursors for starch biosynthesis.