1,2-Propanediol production from glycerol via an endogenous pathway of Klebsiella pneumoniae

Klebsiella pneumoniae is an important microorganism and is used as a cell factory for many chemicals production. When glycerol was used as the carbon source, 1,3-propanediol was the main catabolite of this bacterium. K. pneumoniae ΔtpiA lost the activity of triosephosphate isomerase and prevented glycerol catabolism through the glycolysis pathway. But this strain still utilized glycerol, and 1,2-propanediol became the main catabolite. Key enzymes of 1,2-propanediol synthesis from glycerol were investigated in detail. dhaD and gldA encoded glycerol dehydrogenases were both responsible for the conversion of glycerol to dihydroxyacetone, but overexpression of the two enzymes resulted in a decrease of 1,2-propanediol production. There are two dihydroxyacetone kinases (I and II), but the dihydroxyacetone kinase I had no contribution to dihydroxyacetone phosphate formation. Dihydroxyacetone phosphate was converted to methylglyoxal, and methylglyoxal was then reduced to lactaldehyde or hydroxyacetone and further reduced to form 1,2-propanediol. Individual overexpression of mgsA, yqhD, and fucO resulted in increased production of 1,2-propanediol, but only the combined expression of mgsA and yqhD showed a positive effect on 1,2-propanediol production. The process parameters for 1,2-propanediol production by Kp ΔtpiA-mgsA-yqhD were optimized, with pH 7.0 and agitation rate of 350 rpm found to be optimal. In the fed-batch fermentation, 9.3 g/L of 1,2-propanediol was produced after 144 h of cultivation, and the substrate conversion ratio was 0.2 g/g. This study provides an efficient way of 1,2-propanediol production from glycerol via an endogenous pathway of K. pneumoniae

Flecainide Is Associated With a Lower Incidence of Arrhythmic Events in a Large Cohort of Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

BACKGROUND: In severely affected patients with catecholaminergic polymorphic ventricular tachycardia, beta-blockers are often insufficiently protective. The purpose of this study was to evaluate whether flecainide is associated with a lower incidence of arrhythmic events (AEs) when added to beta-blockers in a large cohort of patients with catecholaminergic polymorphic ventricular tachycardia. METHODS: From 2 international registries, this multicenter case cross-over study included patients with a clinical or genetic diagnosis of catecholaminergic polymorphic ventricular tachycardia in whom flecainide was added to beta-blocker therapy. The study period was defined as the period in which background therapy (ie, beta-blocker type [beta1-selective or nonselective]), left cardiac sympathetic denervation, and implantable cardioverter defibrillator treatment status, remained unchanged within individual patients and was divided into pre-flecainide and on-flecainide periods. The primary end point was AEs, defined as sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter defibrillator shock, and arrhythmic syncope. The association of flecainide with AE rates was assessed using a generalized linear mixed model assuming negative binomial distribution and random effects for patients. RESULTS: A total of 247 patients (123 [50%] females; median age at start of flecainide, 18 years [interquartile range, 14-29]; median flecainide dose, 2.2 mg/kg per day [interquartile range, 1.7-3.1]) were included. At baseline, all patients used a beta-blocker, 70 (28%) had an implantable cardioverter defibrillator, and 21 (9%) had a left cardiac sympathetic denervation. During a median pre-flecainide follow-up of 2.1 years (interquartile range, 0.4-7.2), 41 patients (17%) experienced 58 AEs (annual event rate, 5.6%). During a median on-flecainide follow-up of 2.9 years (interquartile range, 1.0-6.0), 23 patients (9%) experienced 38 AEs (annual event rate, 4.0%). There were significantly fewer AEs after initiation of flecainide (incidence rate ratio, 0.55 [95% CI, 0.38-0.83]; P=0.007). Among patients who were symptomatic before diagnosis or during the pre-flecainide period (n=167), flecainide was associated with significantly fewer AEs (incidence rate ratio, 0.49 [95% CI, 0.31-0.77]; P=0.002). Among patients with ≥1 AE on beta-blocker therapy (n=41), adding flecainide was also associated with significantly fewer AEs (incidence rate ratio, 0.25 [95% CI, 0.14-0.45]; P&lt;0.001). CONCLUSIONS: For patients with catecholaminergic polymorphic ventricular tachycardia, adding flecainide to beta-blocker therapy was associated with a lower incidence of AEs in the overall cohort, in symptomatic patients, and particularly in patients with breakthrough AEs while on beta-blocker therapy.</p

Flecainide Is Associated With a Lower Incidence of Arrhythmic Events in a Large Cohort of Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

BACKGROUND: In severely affected patients with catecholaminergic polymorphic ventricular tachycardia, beta-blockers are often insufficiently protective. The purpose of this study was to evaluate whether flecainide is associated with a lower incidence of arrhythmic events (AEs) when added to beta-blockers in a large cohort of patients with catecholaminergic polymorphic ventricular tachycardia. METHODS: From 2 international registries, this multicenter case cross-over study included patients with a clinical or genetic diagnosis of catecholaminergic polymorphic ventricular tachycardia in whom flecainide was added to beta-blocker therapy. The study period was defined as the period in which background therapy (ie, beta-blocker type [beta1-selective or nonselective]), left cardiac sympathetic denervation, and implantable cardioverter defibrillator treatment status, remained unchanged within individual patients and was divided into pre-flecainide and on-flecainide periods. The primary end point was AEs, defined as sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter defibrillator shock, and arrhythmic syncope. The association of flecainide with AE rates was assessed using a generalized linear mixed model assuming negative binomial distribution and random effects for patients. RESULTS: A total of 247 patients (123 [50%] females; median age at start of flecainide, 18 years [interquartile range, 14-29]; median flecainide dose, 2.2 mg/kg per day [interquartile range, 1.7-3.1]) were included. At baseline, all patients used a beta-blocker, 70 (28%) had an implantable cardioverter defibrillator, and 21 (9%) had a left cardiac sympathetic denervation. During a median pre-flecainide follow-up of 2.1 years (interquartile range, 0.4-7.2), 41 patients (17%) experienced 58 AEs (annual event rate, 5.6%). During a median on-flecainide follow-up of 2.9 years (interquartile range, 1.0-6.0), 23 patients (9%) experienced 38 AEs (annual event rate, 4.0%). There were significantly fewer AEs after initiation of flecainide (incidence rate ratio, 0.55 [95% CI, 0.38-0.83]; P=0.007). Among patients who were symptomatic before diagnosis or during the pre-flecainide period (n=167), flecainide was associated with significantly fewer AEs (incidence rate ratio, 0.49 [95% CI, 0.31-0.77]; P=0.002). Among patients with ≥1 AE on beta-blocker therapy (n=41), adding flecainide was also associated with significantly fewer AEs (incidence rate ratio, 0.25 [95% CI, 0.14-0.45]; P&lt;0.001). CONCLUSIONS: For patients with catecholaminergic polymorphic ventricular tachycardia, adding flecainide to beta-blocker therapy was associated with a lower incidence of AEs in the overall cohort, in symptomatic patients, and particularly in patients with breakthrough AEs while on beta-blocker therapy.</p

Leren van het energieke platteland : lokale en regionale coalities voor duurzame plattelandsontwikkeling

In deze studie onderzoeken we de kracht van de samenwerking tussen de verschillende gebruikers van het platteland. Burgers, boeren, natuurbeheerders en bedrijven die samen initiatieven ontplooien om hun leefomgeving te verbeteren. De studie laat aan de hand van een breed scala aan praktijkvoorbeelden zien hoe ze dat doen, wat ze proberen te bereiken en waar ze tegenaan lopen. Zo zijn er moderne boeren die samen met andere ketenpartijen hun bedrijfsvoering nog verder willen verduurzamen dan de wet al voorschrijft, en burgers die met boeren lokale coöperaties opzetten voor de opwekking van hernieuwbare energie

O NEOBIČNOM SLUČAJU SPIRANTIZACIJE U SRPSKO-ENGLESKOJ MEĐUJEZIČKOJ FONOLOGIJI

The paper explores a subtype of the phonological process of lenition, more precisely, the phenomenon of spirantization in the Serbian-English interlanguage system. During the process of spirantization, plosive sounds transform into fricatives and the factors causing altered realizations may stem from various sources, the most prominent being mother tongue interference. For example, due to the specific pronunciation of alveolar stops and fricatives in L1, Spanish learners of English as a foreign language tend to transfer the feature into their L2, causing thus all voiced plosives, regardless of the place of articulation, to transform into fricatives (Zampini 2008). However, the phonological system of Serbian is not characterized by the same processes, hence, the occasional spirantization in the interlanguage system, we argue, cannot be derived from mother tongue interference, yet may be the result of other factors, such as, qualitative hypercorrection. The analyzed corpus was obtained from the recordings of a spontaneous speech by 15 Serbian English-major students at the tertiary level of education. We investigated the instances of spirantization using the methods of acoustic analysis and spectrographic illustrations via Praat, version 6.2.04. The findings indicated that only alveolar plosives (both voiced and voiceless) were spirantized, most frequently in accented position. Regarding the phonetic environment, the word-initial pre-vocalic position, as well as the word-final post-vocalic and post-consonantal position, triggered the highest frequency of spirantization occurrence. Acoustic measurements confirm the initial assumptions regarding the specific nature of spirantized variants [dz], [ts], [ð] and [θ]. The results have important pedagogical implications and provide insights into the complexity of cross-linguistic influence.Publishe

“I WENT TO VENICE AND WAS VERY WORRIED.” – DIFERENCIJALNA SUPSTITUCIJA /v/-/w/ KONTRASTA U ENGLESKO-SRPSKOJ MEĐUJEZIČKOJ FONOLOGIJI

Previous findings of SLA research underlined the significance of differential substitution as one of the most common strategies for overcoming difficulties in pronouncing English consonants. The acquisition of /v/-/w/ contrast seems particularly demanding for Serbian EFL learners, due to diverse factors, the dominant one being mother tongue interference and the resulting perceptual assimilation. Having the previously stated in mind, as well as the scarcity of research in the Serbian scientific context, the present study aimed at investigating instances of differential substitution of the English labiodental fricative and the labial-velar approximant in relation to the phonetic context and the formality of task type. Both the perception and production of a total of 72 English-major students were tested using different instruments, including phonemic discrimination task, wordlist as well as paragraph reading, and the interview. The obtained data were quantitatively analyzed and supported by spectrogram illustrations of both native and non-native speakers of English. The results indicate a greater frequency of /v/-substitution ([w] being the main substitute) with phonetic context and task type playing a statistically significant role in differential substitution. Instances of substitution of the labial-velar approximant were not as frequent and are said to be characteristic of a specific group of learners (Serbian labiodental sonorant [ʋ] being the main substitute). The results underscore the variability and complexity of the interlangauge system and the importance of valuing the process, and not merely the outcomes of L2 sound acquisition.Publishe

Cost analysis of enzymatic biodiesel production in small-scaled packed-bed reactors

A cost analysis of enzymatic biodiesel production in small-scaled packed-bed reactors using refined sunflower oil is performed in this work. A few enzymatic micro-flow reactors have so far reached a performance close to gram-scale, which might be sufficient for the pharmaceutical industry. This study, motivated by the availability of new immobilization materials and techniques, wants to go one step further and explore the application of enzymatic micro-flow reactors to the biofuel market, which is much larger in volume. However, there are certain hurdles which need to be overcome to ensure commercialization of this process; this requires a simultaneous multi-innovation approach, which has been reviewed in the introduction. A detailed analysis of the two main hurdles – lipase production & immobilization, and severe mass transfer limitations – along with the state-of-the-art, and forecasted innovations, has also been provided. The basic input data for the cost evaluation was taken from performance data of enzymatic micro-flow reactors published in literature, and certain assumptions (based on this data). The costs of enzymatic biodiesel production are also benchmarked against those of a real biodiesel production plant. It is found that a major cost for the scaled-up flow case is the enzyme cost. This is intrinsic to the approach adopted here; it adds process intensification value (here towards new resources: waste oils), and has to be accepted. Yet, an even bigger cost issue is the support material itself. The current costs of the commercial available Eupergit CM polymeric resin may allow its use in pharmaceutical manufacturing, but are prohibitively high for large-volume biodiesel production. The use of a similarly-functional polymer, which is simple to manufacture and lower in costs, is strongly advised, and we have chosen the SEPABEADS EC-EP/M carrier for this. An optimistic scenario is proposed with the following assumptions: use of the cheap SEPABEADS EC-EP/M carrier, utilization of refined sunflower oil as raw material, improved immobilization efficiency in regard to higher activity retention and enzyme loading, and increase in number of reuse of immobilized lipase. Following this, a production scenario for the enzyme-based biodiesel processing using refined sunflower oil at 10,000 t/a capacity can be made using 32 parallel reactors with 10 cm diameter and 100 cm length