Biomechanical reconstructions and selective advantages of neck poses and feeding strategies of Sauropods with the example of Mamenchisaurus youngi.

A very long neck is a characteristic feature of most sauropod dinosaurs. In the genus Mamenchisaurus, neck length is extreme, greater than 40 percent of total body length. However, the posture, utilization, and selective advantage of very long necks in sauropods are still controversial. An excellently preserved skeleton of Mamenchisaurus youngi, including a complete neck, provides an opportunity for a comprehensive biomechanical analysis of neck posture and mobility. The biomechanical evidence indicates that Mamenchisaurus youngi had a nearly straight, near horizontal neck posture and browsed at low or medium heights. The results differ from the findings for some other sauropod species, like Euhelopus, Diplodocus, and Giraffatitan (Brachiosaurus) that had been analyzed in previous studies with similar methods. The selective advantage of extreme neck length in sauropods is likely advantageous for different feeding strategies.

A case of focal nodular hyperplasia with a new characteristic finding on contrast-enhanced ultrasonography using Levovist.

We used contrast-enhanced ultrasound with Levovist, a microbubble contrast agent, to diagnose a case of hepatic focal nodular hyperplasia (FNH). A new characteristic finding of heartbeat-synchronized centrifugal enhancement was discovered. We call this enhancement pattern the "sonographic fireworks sign." It is expected to be useful for diagnosing FNH, especially when the lesions are small and it is difficult to depict a spoke-wheel pattern.

Molecular mechanisms of hereditary persistence of alpha-fetoprotein (AFP) in two Japanese families A hepatocyte nuclear factor-1 site mutation leads to induction of the AFP gene expression in adult livers.

alpha-Fetoprotein (AFP) is produced abundantly in fetal liver but is hardly detectable in adults. In this study, we investigated two unrelated Japanese families with hereditary persistence of AFP. A g-->a substitution at nucleotide -119 (-119g-->a) in the hepatocyte nuclear factor (HNF)-1 binding site of the AFP promoter was identified in both families. The activity of the wild- or variant-type human AFP promoter was evaluated by in vitro and in vivo transfection experiments. This substitution in the AFP promoter significantly stimulated its transcriptional activity in human hepatoma cells, regardless of their prior AFP production. The variant-type AFP promoter was also active in adult mouse livers in vivo. Additionally, overexpression of HNF-1alpha stimulated the activity of both the wild- and variant-type AFP promoters in hepatoma cells. HNF-1alpha expression also activated both AFP promoters even in nonhepatoma cells, and this activation was suppressed by nuclear factor (NF)-I overexpression. These results indicate that an HNF-1 binding site mutation leads to induction of the AFP gene expression in adult liver, and suggest that competition between HNF-1 and NF-I in this region is involved in transcriptional regulation of the AFP gene during hepatic development.