Short communication: Regulation of hepatic gluconeogenic enzymes by dietary glycerol in transition dairy cows.

Nutritional status and glucose precursors are known regulators of gluconeogenic gene expression. Glycerol can replace corn in diets fed to dairy cows and use of glycerol is linked to increased rumen propionate production. The effect of dietary glycerol on the regulation of gluconeogenic enzymes is unknown. The objective of this study was to examine the effect of glycerol on expression of pyruvate carboxylase (PC), cytosolic and mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-C and PEPCK-M), and glucose-6-phosphatase. Twenty-six multiparous Holstein cows were fed either a control diet or a diet where high-moisture corn was replaced by glycerol from -28 through +56 d relative to calving (DRTC). Liver tissue was collected via percutaneous liver biopsy at -28, -14, +1, +14, +28, and +56 DRTC for RNA analysis. Expression of PC mRNA increased 6-fold at +1 and 4-fold at +14 DRTC relative to precalving levels. Dietary glycerol did not alter expression of PC mRNA expression. Expression of PEPCK-C increased 2.5-fold at +14 and 3-fold at +28 DRTC compared with +1 DRTC. Overall, dietary glycerol increased PEPCK-C expression compared with that of cows fed control diets. The ratio of PC to PEPCK-C was increased 6.3-fold at +1 DRTC compared with precalving and tended to be decreased in cows fed glycerol. We detected no effect of diet or DRTC on PEPCK-M or glucose-6-phosphatase mRNA, and there were no interactions of dietary treatment and DRTC for any transcript measured. Substituting corn with glycerol increased the expression of PEPCK-C mRNA during transition to lactation and suggests that dietary energy source alters hepatic expression. The observed increase in PEPCK-C expression with glycerol feeding may indicate regulation of hepatic gene expression by changes in rumen propionate production.

Melnick-Needles syndrome in males: a lethal multiple congenital anomalies syndrome.

A male fetus with decreased calvarial mineralization and suspected omphalocele was identified prenatally in a woman with oligohydramnios and Melnick-Needles syndrome (MNS). At autopsy, exophthalmos, prune belly sequence with urethal atresia and megacystis, tetralogy of Fallot, atrioventricular canal defect, and complete malrotation of the gut were identified. Mandibular hypoplasia and delicate, bowed, irregular, long bones and ribs with widening and deep cupping of the metaphyses were found radiographically. In addition, we review 3 previously reported cases of males with similar, lethal malformations, all born to mothers with MNS. It is our conclusion that these anomalies characterize the male MNS phenotype. A review of all reported viable individuals with MNS identified 2 distinct entities: a mild form found only in females, compatible with normal life expectancy in most cases and inherited in an X-linked dominant male lethal or sex limited autosomal dominant pattern, and a different, more severe disorder, termed precocious osteodysplasty, found in both males and females and inherited as an autosomal recessive trait.