Isobutanol, in spite of its significant superiority over ethanol as a biofuel, remains commercially non-viable due to the non-availability of a suitable chassis which can handle the solvent toxicity associated with its production. to meet this challenge, we chose Lactococcus lactis which is known for its ability to handle environmental stress and carried out Adaptive laboratory evolution (ALe) in a continuous stirred tank reactor (cStR) to evolve an isobutanol tolerant strain. the strain was grown for more than 60 days (> 250 generations) while gradually increasing the selection pressure, i.e. isobutanol concentration, in the feed. this led to the evolution of a strain that had an exceptionally high tolerance of up to 40 g/l of isobutanol even though a scanning electron microscope (SEM) study as well as analysis of membrane potential revealed only minor changes in cellular morphology. Whole genome sequencing which was done to confirm the strain integrity also showed comparatively few mutations in the evolved strain. However, the criticality of these mutations was reflected in major changes that occurred in the transcriptome, where gene expression levels from a wide range of categories that involved membrane transport, amino acid metabolism, sugar uptake and cell wall synthesis were significantly altered. Analysing the synergistic effect of these changes that lead to the complex phenotype of isobutanol tolerance can help in the construction of better host platforms for isobutanol production. The growing demands for energy in the world economy, coupled with the opposing need to reduce our carbon footprint, has spurred research in the area of biofuels. Thus, major gains have been made in last decade, where systems biology approaches have been successfully combined with metabolic engineering and synthetic biology tools, to engineer microbes to produce advanced biofuels. However, we still have a long way to go before commercial production of these biofuels takes place. This is because of multiple bottlenecks in the process; one of the primary ones being the poor tolerance of these microbes for the product. This feedback inhibition by higher alcohols effectively ensures that the final product titers are so low as to make the production process economically unviable 1. Attempts to engineer solvent tolerance in a host have been mixed bag of success 2. Each organism has its own intrinsic solvent tolerance level, which is genetically determined and environmentally influenced. Therefore, organic solvent tolerance is believed to be a strain-specific property 3,4. The host response to solvent toxicity involves the induction of a complex stress response at the global level. Studies have shown that many strains of Saccharomyces cerevisiae exhibit restricted growth in 20 g/l butanol while lactic acid bacteria (LAB) including Lactobacillus delbrueckii and Lactobacillus brevis can grow in 30 g/l butanol. Strains of Clostridia are unable to tolerate more than 20 g/l butanol while Escherichia coli and Zymomonas mobilis strains showe...
Background: The prevalence of right bundle branch block (RBBB) is estimated in 0.2 to 1.3% of healthy people. RBBB had independent association with decreased right ventricle (RV) function, which is considered as predictor of adverse cardiovascular outcomes. The aim of this study is to evaluate RV structure and function in patients with isolated RBBB (without structural heart disease) using two-dimensional echocardiography. Methods: A cross-sectional study conducted at Chitwan Medical College, Bharatpur from 1st January 2022 to 30th June 2022. Consecutive adult patients aged ≥18 years with isolated RBBB classified into complete RBBB (CRBBB) and Incomplete RBBB (IRBBB) based on electrocardiographic findings. The echocardiographic evaluation was done to assess RV dimension and function. Results: A total of 52 patients with isolated RBBB were included with mean age of the study population was 45.3 ± 9.3 years, (28 ,53.8%) had CRBBB, whereas the remaining (24, 46.2%) had IRBBB. Among the parameters used to assess RV function; mean RV-Fractional area change (P<0.001), Tricuspid annular plane systolic excursion(P<0.02) and Pulsed Doppler peak velocity at the lateral annulus RV(P<0.001) were significantly lower, while Pulsed Doppler myocardial performance index(P<0.001) was significantly high in CRBBB group as compared to IRBBB group. Similarly, Right atrium and RV dimensional parameters were significant higher in CRBBB compared to IRBBB group. Conclusions: Isolated RBBB is not as benign as it was considered and has deteriorating effect on RV morphology and function. Therefore, patients with Isolated RBBB need follow-up with passing age and more attention toward RV structural and functional analysis.
Background: Electrical injury and its consequences after exposure to electric shock has been associated with an increased risk of developing immediate and delayed cardiac arrhythmias. The aim of this study was to evaluate the prevalence of cardiac arrhythmias and different symptoms in patient with high voltage and low voltage electrical injury. Methods: All 50 consecutive patients who were admitted in Chitwan Medical College from April 2018 to March 2020 were prospectively studied. Patients were categorized into high and low voltage injury group and their variables were compared. Results: The mean age of the patients was 32.3±10.4 years among them 41 (82%) were male. Patients who sustain high voltage electrical injury (>1000V) were 18 (36%) and low voltage injury (<1000V) were 32 (64%). Cardiac arrhythmias like sinus tachycardia (11.1% vs 6.2%, p=0.054), sinus bradycardia (11.1% vs 3.1% p=0.254), ventricular premature beats (5.6% vs3.1%, p=0.674), atrial fibrillation (11.1% vs 0%, p=0.054) were observed in high voltage and low voltage group. The commonest presenting symptoms in both groups were pain (77.8% vs 84.4% p=0.560) and fatigue (55.6% vs 40.6%, p=0.328). Conclusion: In this study few non fatal cardiac arrhythmias were observed in both high and low voltage electrical injury group. There is no significant difference in the presenting symptoms and types of arrhythmias observed between low voltage and high voltage injury group.
Background To identify the CT features of anterior mediastinal thymoma and lymphoma and evaluate CT findings that may help in suggesting specific diagnosis among these tumors. Method A total of fifty-eight chest CT scan studies with pathological diagnosis of thymoma (n = 30) and lymphoma (n =28) were retrospectively reviewed by two radiologists who were blind to the pathological results. The CT features showing cyst and calcification within the lesion, contrast enhancement, relation with pleura and adjacent vessels, bone invasion and lymph node enlargement were evaluated. Results In lymphoma (67.9%), the presence of associated mediastinal lymphadenopathy was significantly compared to thymoma. (P < 0.05). The presence of calcification within the lesion was significantly found in thymoma than the lymphoma (p <0.05). The presence of adjacent vessels relationship within the lesion was higher in lymphoma than the thymoma. (p <0.05) The remaining CT findings showed no significant difference among these diseases (p > 0.05). Conclusion In conclusion age, lymph nodes involvement, calcification and relationship to adjacent vessels on CT scan will be helpful to give specific diagnosis on anterior mediastinum lymphoma and thymoma. .
Background Lingual orthodontics (LiO) has developed rapidly in recent years and research on treatment of overbite by using Rocking Chair Arch (RCA) wire of different curve depths is still limited, especially with 3-dimensional Finite Element (FE) models. The main objectives are to study the biomechanical differences in maxillary anterior teeth between lingual and labial orthodontics and observe the lingual mechanics on different inclinations of teeth. Methods The force produced by Nickel-Titanium, Stainless Steel (SS) RCA for both sides was measured using Electromechanical Universal Testing Machine. 6 FE models were constructed and divided into 2 groups according to SS wire of 0.016x0.022-inch standard and mushroom arch shaped RCA of curve depth 2, 4, 6 mm. Additional 9 FE models were constructed and divided into 3 groups based on Retroclination (-5°, -10°) and Proclination (+10°). Results Use of same diameter of SS RCA with same curve depth but on different sides shows more stress and strain, displacement of teeth in lingual mechanics. Also, stress-strain, displacement increased with increasing RCA curve depth. In LiO, intrusion of normally inclined or proclined teeth are accompanied by little or no labial tipping whereas that of retroclined teeth is accompanied by further lingual tipping. Conclusion In the intrusion using Lingual RCA, to avoid the traumatic force to teeth, the curve depth should be lesser than Labial RCA or apply more elastic arch material; Aligning different inclined teeth into normal inclination firstly and proceed with the application of intrusive force can be the best approach.
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