Mathematical modeling of induced foreign protein production by recombinant bacteria

A new generalized mathematical model for recombinant bacteria which includes inducer effects on cell growth and foreign protein production is developed. The model equation set was applied to a host-vector system, Escherichi coli D1210 and plasmid pSD8. Batch experiments were designed and performed in shake flasks to verify the model. A parameter estimation method was developed and proven to be efficient. Although simple, the model can effectively describe the dynamics of the production of foreign protein in recombinant bacteria and can be used for optimization and control studies to maximize foreign protein production.

Risk factors for treatment failure in patients with prosthetic joint infections

A retrospective, observational cohort study was conducted to describe the incidence, clinical and microbiological findings and to evaluate risk factors for treatment failure associated with prosthetic joint infections (PJIs). We retrospectively reviewed the medical records of all patients undergoing total knee or total hip prosthesis implantation in our institution between 1994 and 2008. Our institution is a 1950-bed tertiary care university hospital and referral centre. A total of 93 patients with PJIs was identified although only 68 patients had undergone prosthesis implantation at our hospital. The overall infection rate was 0.63%. The most common organisms isolated were Gram positive (76.5%), including meticillin-resistant staphylococci. Two-stage arthroplasty was performed in 48 (51.6%) patients, and debridement and retention of the prosthesis in 34 (36.5%) patients. When 43 patients followed up for more than two years after treatment were included in treatment outcome analysis, the overall treatment failure rate was 41.8% (18/43). Staphylococcus aureus infection was the only clinical variable associated with treatment failure (odds ratio: 11.9; 95% confidence interval: 1.07-133.9; P=0.044), after adjustment for the other variables. In conclusion, S. aureus was the most common pathogen isolated in patients with PJI, and an independent risk factor for treatment failure in patients with PJI.

EPHX1 polymorphisms, COPD and asthma in 47,000 individuals and in meta-analysis

We tested the hypothesis that two well-characterised functional polymorphisms of the microsomal epoxide hydrolase gene (EPHX1), T113C and A139G, may influence susceptibility to chronic obstructive pulmonary disease (COPD) and asthma. We genotyped participants from the Copenhagen City Heart Study (n = 10,038) and the Copenhagen General Population Study (n = 37,022) for the T113C and A139G variants in the EPHX1 gene and measured lung function and recorded COPD hospitalisation and asthma and smoking history. Finally, we meta-analysed results from 19 studies including 7,489 COPD cases and 42,970 controls. The OR for spirometry-defined COPD or COPD hospitalisation did not differ from 1.0 for any of the EPHX1 genotypes or phenotypes overall, or in smokers or nonsmokers separately (p-value for trend 0.18-0.91). Likewise, EPHX1 genotypes or phenotypes did not associate with risk of asthma (p-value for trend 0.46-0.98). In meta-analysis, random effects OR for COPD in T113C heterozygotes and homozygotes versus non-carriers were 1.17 (0.99-1.38) and 1.38 (1.09-1.74), respectively. Corresponding values for A139G were 0.93 (0.83-1.05) and 0.89 (0.78-1.02). Our results indicate that genetically reduced microsomal epoxide hydrolase activity is not a major risk factor for COPD or asthma in the Danish population; however, meta-analysis cannot completely exclude a minor effect on COPD risk.