History of Stepped Channels and Spillways: a Rediscovery of the 'Wheel'

Recently, spillways with a stepped profile have regained interest and favor among design engineers to pass flood waters over the dams. The stepped geometry enhances the energy dissipation above the spillway and reduces the size of a downstream stilling basin. In this paper, the author shows that the technique of stepped channels has been developed since Antiquity. Spillways and irrigation channels with stepped profiles were developed by several civilisations around the Mediterranean sea and in America. The main characteristics of the stepped spillways along the ages suggest a regular evolution rather than a revolution. Present stepped spillways are designed to pass similar discharges as two hundred years ago

Distal airways are protected from goblet cell metaplasia by diminished expression of IL-13 signaling components.

BACKGROUND: Increased mucus production is a critical factor impairing lung function in patients suffering from bronchial asthma, the most common chronic inflammatory lung disease worldwide. OBJECTIVE: This study aimed at investigating whether goblet cell (GC) metaplasia and mucus production are differentially regulated in proximal and distal airways. METHODS: Female Balb/c mice were sensitized to ovalbumin (OVA) and challenged with an OVA-aerosol on two consecutive days for one week (acute) or twelve weeks (chronic). Real-time RT-PCR analysis was applied on microdissected airways. RESULTS: In acutely and chronically OVA-challenged mice GC metaplasia and mucus production was observed in proximal but not in distal airways. In contrast, inflammation reflected by the infiltration of eosinophils and expression of the TH2-type cytokines IL-4 and IL-13 was increased in both, proximal and distal airways. Abundance of IL-13Rα1 was lower in distal airways of healthy control mice. Under acute and chronic OVA-exposure, activation of IL-13Rα1-dependent signaling cascade, reflected by Spdef and Foxo3A transcription factors, was attenuated in distal compared to proximal airways. CONCLUSION & CLINICAL RELEVANCE: These data indicate that distal airways might be less sensitive to IL-13 induced GC metaplasia and mucus production through lower expression of IL-13Rα1 and attenuated activation of downstream signaling. This might represent a protective strategy in order to prevent mucus plugging of distal airways and thus, impaired ventilation of attached alveoli

Tandem B1 SINE retro-elements may provide a basis for natural antisense transcription in the Magi1 locus of the mouse (Mus musculus)

Transposable elements, which are DNA sequences that can move between different sites in genomes, comprise approximately 40% of the genome of mammals and are emerging as important contributors to biological diversity. Here we report a transcription unit lying within intron 1 of the murine Magi1 (membrane associated guanylate kinase inverted 1) gene that codes for a cell-cell junction scaffolding protein. The transcription unit, termed Magi1OS (Magi1 Opposite Strand), originates from a region with tandem B1 short interspersed nuclear elements (SINEs) and is an antisense gene to Magi1. Mag1OS transcription initiates in a proximal B1 element that shows only 4% divergence from the consensus sequence, indicating that it has been recently inserted into the mouse genome and could be replication competent. Moreover, a chimaeric transcript may result from intra-chromosomal interaction and trans-splicing of the Magi1 antisense transcript (Magi1OS) and Ghrl, which codes for the multifunctional peptide hormone ghrelin. These two genes are 20 megabases apart on chromosome 6 and are transcribed in opposite directions. We propose that the Magi1OS locus may serve as a useful model system to study exaptation and retrotransposition of B1 SINEs, as well as to examine the mechanisms of intra-chromosomal trans-splicing