Survival and stress induced expression of groEL and rpoD of Campylobacter jejuni from different growth phases36763

Although Campylobacter jejuni is the leading cause of bacterial diarrhoeal disease in humans worldwide, its potential to adapt to the stressful conditions and survive in extra-intestinal environment is still poorly understood. We tested the effect of heat shock (55 degrees C, 3 min) and oxidative stress (3 mM H2O2 for 10 min or prolonged incubation at atmosphere oxygen concentration) on non-starved and starved cells of Campylobacter jejuni from different growth phases. Viability as assessed with the Bacterial Viability Kit LIVE/DEAD BacLighttrade mark dying before fluorescent microscopy and culturability of the cells (CFU ml(-1)) from both growth phases showed that starvation increased heat but not oxidative resistance. High temperature and oxidative stress invoked quick transformation from culturable spiral shaped to nonculturable spiral and coccoid cells. Despite physiological changes of the cells we were not able to document clear differences in the expression of heat shock and starvation genes (dnaK, htpG, groEL), oxidative (ahpC, sodB), virulence (flaA) and housekeeping genes (16S rRNA, rpoD) after heat treatment (55 degrees C, 3 min) or oxidative stresses applied. When starving, no induction of expression of any of these genes was noticed, chloramphenicol had no influence on their gene expression. Quantitative real-time PCR analyses showed that at least 10-20 min of heat shock was necessary to evidently increase the amount of groEL and rpoD transcripts</p

In vitro effect of the common culinary herb winter savory (Satureja montana) against the infamous food pathogen campylobacter jejuni

The culinary herb Satureja montana, known as winter savory, is an ingredient of traditional dishes known in different parts of the world. As an ingredient of foods it has the potential to improve their safety. In this study, the herb's activity was investigated against Campylobacter jejuni, the leading cause of the most prevalent bacterial gastroenteritis worldwide. The ethanolic extract and essential oil of the herb were chemically characterized and six pure compounds-carvacrol, thymol, thymoquinone, p‐cymene, γ‐terpinene, and rosmarinic acid-were chosen for further analysis. The antimicrobial activity of the ethanolic extract (MIC 250 mg/L) was 4‐fold higher compared to the essential oil. Carvacrol, thymol and thymoquinone had the strongest antimicrobial effect (MIC 31.25 mg/L) and a strong synergistic activity between carvacrol and thymol was determined (FICi 0.2). Strong inhibitory effect on C. jejuni efflux pumps (2‐fold inhibition) and disruption of membrane integrity (&gt; 80% disruption) of the herb were determined as modes of action. For resistance against the herb, C. jejuni need efflux pumps, although increased resistance against this herb does not co‐occur with increased efflux pump activity, as for antibiotics. This study shows the potential of a common culinary herb for the reduction of the food pathogen C. jejuni without increasing resistance

Intravitreal triamcinolone for the treatment of refractory diabetic macular oedema with hard exudates: an optical coherence tomography study

Aim: To investigate the use of intravitreal triamcinolone acetonide (IVTA) for the treatment of diabetic macular oedema (DMO) unresponsive to previous laser photocoagulation. Method: A retrospective, interventional, non-comparative case series. There were 30 eyes of 22 consecutive patients with refractory DMO. An intravitreal injection of triamcinolone acetonide at the dose of 4 mg in 0.1 ml was administered. Best corrected visual acuity was measured at each examination. In addition the central macular thickness was quantitatively measured by optical coherence tomography (OCT) examination at each visit. The amount of hard exudates deposition in the macula was subjectively evaluated using colour fundus photographs. Results: 30 eyes of 22 patients completed 6 months or more of follow up and were included in the study. Mean (SD) visual acuity improved from 0.17 (0.12) at baseline to 0.34 (0.18), 0.36 (0.16), and 0.31 (0.17) at the 1, 3, and 6 month follow up respectively. Mean (SD) OCT macular thickness decreased from 476 (98.32) μm at baseline to 277.46 (96.77) μm, 255.33 (95.73) μm, and 331.25 (146.76) μm at the 1, 3, and 6 month follow up period respectively. 18 and seven eyes completed 12 months and 18 months of follow up, respectively. Mean (SD) visual acuity was 0.36 (0.15) and 0.35 (0.16) at the 12 and 18 month follow up period respectively. 12 eyes received two, seven eyes received three, and two eyes received four IVTA injections. The mean (SD) interval between the first and second IVTA injection was 5.7 (2.67) months and between the second and third was 5.7 (3.25) months. Hard exudates were present in the macula at baseline in all eyes. Progressive reduction in the number and size of the hard exudates was noted after IVTA in all cases. Intraocular pressure was raised above 21 mm Hg in 12 (40%) of 30 eyes. Two eyes developed posterior subcapsular cataract and two developed vitreous haemorrhage. Conclusions: IVTA is a promising treatment for patients with DMO refractory to laser treatment. IVTA is effective in improving vision, reducing macular thickness, and inducing reabsorption of hard exudates. Further investigation is warranted to assess the safety of IVTA for the treatment of DMO

Particle swarm optimization approach for modelling a turning process,

This paper proposes the modelling of a turning process using particle swarm optimization (PSO). The independent input machining parameters for the modelling were cutting speed, feed rate, and cutting depth. The input parameters affected three dependent output parameters that were the main cutting force, surface roughness, and tool life. The values of the independent and dependent parameters were acquired by experimental work and served as knowledge base for the PSO process. By utilizing the knowledge base and the PSO approach, various models could be acquired for describing the cutting process. In our case, three different polynomial models were obtained: models a) for the main cutting force, b) for surface roughness, and c) for tool life. All the models had exactly the same basic polynomial form which was chosen similarly to that in the conventional regression analysis method. The PSO approach was used for optimization of the polynomials&apos; coefficients. Several different randomly-selected data sets were used for the learning and testing phases. The accuracies of the developed models were analysed. It was discovered that the accuracies of the models for different learning and testing data sets were very good, having almost the same deviations. The least deviation was noted for the cutting force, whilst the most deviation, as expected was for tool life. The obtained models could then be used for later optimization of the turning process