Molecular genetic analysis of chemical-induced sporulation of Myxococcus xanthus

Mutants resistant to glycerol-induction of sporulation were isolated from wild-type M. xanthus. The glycerol-resistant qlrA and alrB loci, previously mapped by Mx.8 transductions, were analysed by restriction mapping of clones and by complementation analysis. The location of the qlrA gene(s) was mapped to within a 2.2kb region, whilst the qlrB region proved very complex. The qlrA and qlrB gene products were reguired early in chemical-induced sporulation since two chemical-inducible lacZ fusions were not expressed in either qlrA or qlrB mutants during chemical-induction. Only a minority of the glycerol-resistant mutants were unable to undergo fruiting body sporulation. Complementation studies of the qlrA and qlrB regions confirmed that mutations in chemical-induced and fruiting body sporulation were not linked. This suggests that the induction pathways of chemical-induced sporulation and fruiting body sporulation share few common genes. Glycerol-resistant mutants were isolated from a non- motile strain, which is unable to form fruiting bodies. The majority of these mutants were able to form spores in the absence of fruiting bodies. Two mutants were unable to form spores. Isolating such mutants may provide a means of identifying truly sporulation-deficient mutants. Expression from the chemical-inducible isqB>lacZ fusion, identified previously in a promoter probe vector, was blocked in 24 different glycerol-resistant mutants. Hence, the gene product was reguired late in the chemical-induced sporulation pathway. The complete transcription unit was cloned and disruption of the region by the insertion of a tetracycline cassette demonstrated that the gene is not essential for chemical- induced or starvation-induced sporulation. Expression from a second chemical-inducible lacZ fusion, ÎÎDK4530, identified previously by random Tn£ lac insertion, was suppressed by amino acids in the growth media during chemical-induced sporulation and was blocked in both qlrA and qlrB mutants. Hence, expression of the gene product is dependent on both the qlrA+ and qlrB+ genes

Analysis of emergency helpline support for home ventilator dependent patients: risk management and workload

From a total of 1211 adult & paediatric patients receiving home ventilation (HV) supervised by Royal Brompton Hospital between 1/1/06 and 30/6/06 the respiratory support team received an average of 528 daytime calls/month and 14/month out of hours calls to a telephone helpline. Diagnoses included: neuromuscular disease, chest wall disease, COPD, obesity hypoventilation and non-COPD lung disease. 99% received non-invasive ventilation, 1% tracheostomy ventilation. 149 required 2 ventilators for near 24 hour ventilator dependency, the remainder were classified as 1 (17%) 2 (33%) & 3 (50%) night dependency as were able to breathe spontaneously for this period. 50% used bilevel positive pressure ventilators, 48% inspiratory pressure ventilators and 2% volume ventilators. In 188 calls a home visit was carried out because of ventilator or associated equipment-related problems. Despite regular equipment servicing programme, in 188 patients there was a technical problem with the equipment which was solved in the patient's home in 64% or required replacement / parts in 22%. Of the 25 calls in which no fault was found, 13 patients were unwell at home or required hospital admission, 2 patients died within 1 month of identification of no fault. No patient was admitted as a result of technical failure of equipment. Conclusion: There is a significant workload associated with supporting HV patients. Patients / carers all received standard competency training before discharge but other calls may be reduced by a more flexible problem-solving approach. Importantly, reports in which no technical fault is found may indicate deteriorating health in the patient and require close follow-up