Two-dimensional gravitactic bioconvection in a protozoan (tetrahymena pyriformis) culture

Gravitactic bioconvective patterns created by Tetrahymena pyriformis in a Hele-Shaw apparatus were realized and compared with theoretical results. There were found to be two thresholds for bioconvection development: the first indicates the transition from the diffusion to the steady convection state; the second corresponds to the transition from the steady to the unsteady convection state. The results showed that the Hele-Shaw apparatus may be used as a physical analogy of porous media to study 2D bioconvection, with possible extensions to larger scale biological systems where population growth and distribution are driven by similar bio-physical interactions.TNQ thanks Prof. N. Lima (Centre for Biological Engineering, University of Minho, Braga, Portugal) for his precious support and Prof. M. P. Sauvant Rochat (Cellular Biology Lab., Universite d'Auvergne, France) for her collaboration. We especially thank Mrs. Laviolette (Ecole Polytechnique de Montreal, Canada), and Mr. Morency and Mrs. Phoenix (University of Montreal, Canada), for their kind assistance. FG acknowledges support from the James S. McDonnell Foundation through a 21st Century Science Initiative award. We thank an anonymous reviewer for his interesting comments

Non-classic cystic fibrosis associated with D1152HCFTR mutation

Background: Limited knowledge exists on phenotypes associated with the D1152H cystic fibrosis transmembrane conductance regulator (CFTR) mutation. Methods: Subjects with a D1152H allele in trans with another CFTR mutation were identified using the French Cystic Fibrosis Registry. Phenotypic characteristics were compared with those of pancreatic insufficient (PI) and pancreatic sufficient (PS) cystic fibrosis (CF) subjects in the Registry (CF cohort). Results: Forty‐two subjects with D1152H alleles were identified. Features leading to diagnosis included chronic sinopulmonary disease (n = 25), congenital absence of the vas deferens (n = 11), systematic neonatal screening (n = 4), and genetic counseling (n = 2). Median age at diagnosis was 33 [interquartile range (IQR, 24–41)] years in D1152H subjects. Median sweat chloride concentrations were 43.5 (39–63) mmol/l in D1152H subjects and were markedly lower than in PI and PS CF subjects (p < 0.05). Bronchiectasis was present in 67% of D1152H subjects, but Pseudomonas aeruginosa colonization and pancreatic insufficiency were present in <30% of subjects. Estimated rates of decline in forced expiratory volume in 1 s (FEV1) were lower in D1152H subjects vs PI CF subjects (p < 0.05). None of the D1152H subjects identified since 1999 had died or required lung transplantation. Conclusions: When present in trans with a CF‐causing mutation, D1152H causes significant pulmonary disease, but all subjects had prolonged survival