Workplace NO and NO2 during combined treatment of infants with nasal CPAP and NO.

OBJECTIVE: To determine the workplace concentrations of NO and NO(2) in and around a paediatric incubator during inhaled NO (iNO) treatment and during an accidental emptying of NO cylinders into room air. DESIGN: We simulated iNO-nasal CPAP treatment in order to assess the impact on the occupational environment. Furthermore, two full NO cylinders for therapy, 1,000 ppm, 20 litres, 150 bar and 400 ppm, 10 litres, 150 bar, were emptied as rapidly as possible into an intensive care unit (ICU) room. SETTING: University hospital ICU. MEASUREMENTS AND RESULTS: To correctly gauge the contribution from iNO-CPAP we constructed a system measuring breathing zone and room ventilation inlet-outlet values during a 10-ppm iNO treatment of a simulated infant. Maximal breathing zone values were 17.9 +/- 7.0 (mean +/- 95% CI) ppb for NO and 25.2 +/- 4.8 ppb for NO(2). If room inlet values were subtracted, the contributions to breathing zone values emanating from iNO-CPAP were 14.8 +/- 4.6 ppb for NO and 14.6 +/- 4.6 ppb for NO(2). At the ventilation outlet the maximal contributions were 4.2 +/- 2.9 ppb NO and 9.6 +/- 4.3 ppb NO(2). During rapid total release of a gas cylinder in the ICU room, simulating an accident, we found transient NO levels comparable to the high therapeutic dosing range, but only low NO(2) levels. CONCLUSIONS: Neither 8-h time-weighted average (TWA) nor 15 min short-term exposure limits (STEL) were exceeded during normal operation or during a simulated accident. The contribution of nitrogen oxides from treatment to workplace air were minor compared to those from ambient air.

Evolutionary innovation in the vertebrate jaw: A derived morphology in anuran tadpoles and its possible developmental origin.

The mouthparts of anuran tadpoles are highly derived compared to those of caecilians or salamanders. The suprarostral cartilages support the tadpole's upper beak; the infrarostral cartilages support the lower beak. Both supra- and infrarostral cartilages are absent in other vertebrates. These differences reflect the evolutionary origin of a derived feeding mode in anuran tadpoles. We suggest that these unique cartilages stem from the evolution of new articulations within preexisting cartilages, rather than novel cartilage condensations. We propose testing this hypothesis through a search for similarities in the development of the suprarostral and infrarostral cartilage articulations and of the primary jaw joint. In Xenopus, the gene zax is expressed in a region corresponding to the infrarostral cartilage. This gene is related to the bapx1-gene, which regulates jaw joint development. Further investigation of these genes, as well as other genes with joint-related functions, in anuran craniofacial development may provide a connection between the morphological diversity seen in the vertebrate head and the corresponding diversity in genetic regulatory processes. We believe that the evolution of larval jaws in anurans may shed light on the general evolutionary mechanisms of how new articulations, not only in the jaw region, could have arisen in the vertebrate skull.

Homology and homocracy revisited: gene expression patterns and hypotheses of homology.

Homocracy, a term referring to shared regulatory gene expression patterns between organs in different animals, was introduced recently in order to prevent inappropriate inference of organ homology based on gene expression data. Non-homologous structures expressing homologous genes, and homologous structures expressing non-homologous genes illustrate that gene expression data is not sufficient on its own to identify morphological homology. However, gene expression data might be useful in testing hypotheses of organ homology, because parsimony can be applied on changes in the relation between expression of orthologous regulatory genes and the formation of homologous organs. A method of testing organ homology hypotheses with respect to change in regulatory gene expression required within a particular phylogenetic context is presented.

Closely related MADS-box genes in club moss (Lycopodium) show broad expression patterns and are structurally similar to, but phylogenetically distinct from, typical seed plant MADS-box genes.

• The relation between the duplication history of the MADS-box gene family of transcription factors and the evolution of plant development is investigated here. The lycopsids, for example the club mosses, constitute the sister group of all other vascular plants, and are therefore interesting from this perspective. • PCR-based methods were used to isolate MADS-box genes from the club moss, Lycopodium annotinum. • In contrast to the previously isolated L. annotinum MADS-box gene LAMB1 (which also contains a so-called K-box), the new L. annotinum genes LAMB2, LAMB4, LAMB6 are structurally similar to most MADS-K-box genes. These genes, and two L. annotinum MADS-box genes, not encoding K-domains, LAMB3 and LAMB5, form a clade distinct from LAMB1. LAMB1 is expressed exclusively in the strobilus unlike LAMB2, LAMB4, LAMB5 and LAMB6, which are expressed in a broad range of organs. • The results imply that the diversification of organ identity MADS-box genes occurred after the split of the lycopsids from the other vascular plants, and that lycopsids have a MADS-box gene family of a type primitive for land plants.