20 research outputs found
Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains
BACKGROUND: Fermentation of lignocellulosic biomass is an attractive alternative for the production of bioethanol. Traditionally, the yeast Saccharomyces cerevisiae is used in industrial ethanol fermentations. However, S. cerevisiae is naturally not able to ferment the pentose sugars D-xylose and L-arabinose, which are present in high amounts in lignocellulosic raw materials. RESULTS: We describe the engineering of laboratory and industrial S. cerevisiae strains to co-ferment the pentose sugars D-xylose and L-arabinose. Introduction of a fungal xylose and a bacterial arabinose pathway resulted in strains able to grow on both pentose sugars. Introduction of a xylose pathway into an arabinose-fermenting laboratory strain resulted in nearly complete conversion of arabinose into arabitol due to the L-arabinose reductase activity of the xylose reductase. The industrial strain displayed lower arabitol yield and increased ethanol yield from xylose and arabinose. CONCLUSION: Our work demonstrates simultaneous co-utilization of xylose and arabinose in recombinant strains of S. cerevisiae. In addition, the co-utilization of arabinose together with xylose significantly reduced formation of the by-product xylitol, which contributed to improved ethanol production
Factors Associated with Worse Lung Function in Cystic Fibrosis Patients with Persistent Staphylococcus aureus
Background Staphylococcus aureus is an important pathogen in cystic fibrosis
(CF). However, it is not clear which factors are associated with worse lung
function in patients with persistent S. aureus airway cultures. Our main
hypothesis was that patients with high S. aureus density in their respiratory
specimens would more likely experience worsening of their lung disease than
patients with low bacterial loads. Methods Therefore, we conducted an
observational prospective longitudinal multi-center study and assessed the
association between lung function and S. aureus bacterial density in
respiratory samples, co-infection with other CF-pathogens, nasal S. aureus
carriage, clinical status, antibiotic therapy, IL-6- and IgG-levels against S.
aureus virulence factors. Results 195 patients from 17 centers were followed;
each patient had an average of 7 visits. Data were analyzed using descriptive
statistics and generalized linear mixed models. Our main hypothesis was only
supported for patients providing throat specimens indicating that patients
with higher density experienced a steeper lung function decline (p<0.001).
Patients with exacerbations (n = 60), S. aureus small-colony variants (SCVs, n
= 84) and co-infection with Stenotrophomonas maltophilia (n = 44) had worse
lung function (p = 0.0068; p = 0.0011; p = 0.0103). Patients with SCVs were
older (p = 0.0066) and more often treated with trimethoprim/sulfamethoxazole
(p = 0.0078). IL-6 levels positively correlated with decreased lung function
(p<0.001), S. aureus density in sputa (p = 0.0016), SCVs (p = 0.0209),
exacerbations (p = 0.0041) and co-infections with S. maltophilia (p = 0.0195)
or A. fumigatus (p = 0.0496). Conclusions In CF-patients with chronic S.
aureus cultures, independent risk factors for worse lung function are high
bacterial density in throat cultures, exacerbations, elevated IL-6 levels,
presence of S. aureus SCVs and co-infection with S. maltophilia. Trial
Registration ClinicalTrials.gov NCT0066976
Regional lung aeration and ventilation during pressure support and biphasic positive airway pressure ventilation in experimental lung injury
INTRODUCTION:
There is an increasing interest in biphasic positive airway pressure with spontaneous breathing (BIPAP+SBmean), which is a combination of time-cycled controlled breaths at two levels of continuous positive airway pressure (BIPAP+SBcontrolled) and non-assisted spontaneous breathing (BIPAP+SBspont), in the early phase of acute lung injury (ALI). However, pressure support ventilation (PSV) remains the most commonly used mode of assisted ventilation. To date, the effects of BIPAP+SBmean and PSV on regional lung aeration and ventilation during ALI are only poorly defined.
METHODS:
In 10 anesthetized juvenile pigs, ALI was induced by surfactant depletion. BIPAP+SBmean and PSV were performed in a random sequence (1 h each) at comparable mean airway pressures and minute volumes. Gas exchange, hemodynamics, and inspiratory effort were determined and dynamic computed tomography scans obtained. Aeration and ventilation were calculated in four zones along the ventral-dorsal axis at lung apex, hilum and base.
RESULTS:
Compared to PSV, BIPAP+SBmean resulted in: 1) lower mean tidal volume, comparable oxygenation and hemodynamics, and increased PaCO2 and inspiratory effort; 2) less nonaerated areas at end-expiration; 3) decreased tidal hyperaeration and re-aeration; 4) similar distributions of ventilation. During BIPAP+SBmean: i) BIPAP+SBspont had lower tidal volumes and higher rates than BIPAP+SBcontrolled; ii) BIPAP+SBspont and BIPAP+SBcontrolled had similar distributions of ventilation and aeration; iii) BIPAP+SBcontrolled resulted in increased tidal re-aeration and hyperareation, compared to PSV. BIPAP+SBspont showed an opposite pattern.
CONCLUSIONS:
In this model of ALI, the reduction of tidal re-aeration and hyperaeration during BIPAP+SBmean compared to PSV is not due to decreased nonaerated areas at end-expiration or different distribution of ventilation, but to lower tidal volumes during BIPAP+SBspont. The ratio between spontaneous to controlled breaths seems to play a pivotal role in reducing tidal re-aeration and hyperaeration during BIPAP+SBmean
Gastroenteropancreatic Neuroendocrine Tumors: Standardizing Therapy Monitoring with Ga-DOTATOC PET/CT Using the Example of Somatostatin Receptor Radionuclide Therapy
The purpose of this study was to standardize therapy monitoring of hepatic metastases from gastroenteropancreatic neuroendocrine tumors (GEP-NETs) during the course of somatostatin receptor radionuclide therapy (SRRT). In 21 consecutive patients with nonresectable hepatic metastases of GEP-NETs, chromogranin A (CgA) and 68 Ga-DOTATOC PET/CT were compared before and after the last SRRT. On 68 Ga-DOTATOC PET/CT, the maximum standard uptake values (SUV max ) of normal liver and hepatic metastases were calculated. In addition, the volumes of hepatic metastases (volume of interest [VOI]) were measured using four cut-offs to separate normal liver tissue from metastases (SUV max of the normal liver plus 10% [VOI liver+10% ], 20% [VOI liver+20% ], 30% [VOI liver+30% ] and SUV = 10 [VOI 10SUV ]). The SUV max of the normal liver was below 10 (7.2 ± 1.3) in all patients and without significant changes. Overall therapy changes (Î) per patient (mean [95% CI]) were statistically significant with p < .01 for ÎCgA = â43 (â69 to â17), ÎSUV max = â22 (â29 to â14), and ÎVOI 10SUV = â53 (â68 to â38)% and significant with p < .05 for ÎVOI liver+10% = â29 (â55 to â3)%, ÎVOI liver+20% = â32 (â62 to â2) and ÎVOI liver+30% = â37 (â66 to â8). Correlations were found only between ÎCgA and ÎVOI 10SUV ( r = .595; p < .01), ÎSUV max and ÎVOI 10SUV (0.629, p < .01), and SUV max and ÎSUV max ( r = .446; p < .05). 68 Ga-DOTATOC PET/CT allows volumetric therapy monitoring via an SUV-based cut-off separating hepatic metastases from normal liver tissue (10 SUV recommended)