Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 7 de 7
Filter
Add more filters










Database
Language
Publication year range
2.
Article in English | MEDLINE | ID: mdl-37368171

ABSTRACT

The nonaqueous catalysis of lipases is significant for synthesis of high pure esters, but they usually behave low catalytic activity due to denaturation and aggregation of enzyme protein in organic phases. To improve the nonaqueous catalysis, the inexpensive copper phthalocyanine was taken as a new carrier on which Pseudomonas cepacia lipase was immobilized by physical absorption, and used for synthesis of hexyl acetate, an important flavor, via transesterification of hexanol and vinyl acetate. Results showed that the desired loading was 10-mg lipase immobilized on 10-mg copper phthalocyanine powder. When the immobilized lipase was employed in the reaction system consisted of 1.5-mL hexanol and 1.5-mL vinyl acetate at 37°C and 160 rpm, the conversion was fivefolds of that catalyzed by native lipase after 1 h, and reached 99.0% after 8 h. In six times of 8-h reuses, the immobilized lipase behaved an activity attenuation rate 1.22% h-1, lower than 1.77% h-1 of native lipase, which meant that the immobilized lipase was more stable. Even at the room temperature and the static state without shaking or stirring, the immobilized lipase still brought conversion 42.8% after 10 h and the native lipase gave 20.1%. Obviously, the immobilized lipase is an available biocatalyst in organic phase and has great potential in food industry.

3.
Appl Biochem Biotechnol ; 194(12): 6302-6318, 2022 Dec.
Article in English | MEDLINE | ID: mdl-35917103

ABSTRACT

The nonaqueous catalysis of lipases is significant for synthesis of high pure esters, but they usually behave low catalytic activity due to denaturation and aggregation of enzyme protein in organic phases. To improve the nonaqueous catalysis, the inexpensive copper phthalocyanine was taken as a new carrier on which Pseudomonas cepacia lipase was immobilized by physical absorption, and used for synthesis of hexyl acetate, an important flavor, via transesterification of hexanol and vinyl acetate. Results showed that the desired loading was 10 mg lipase immobilized on 10 mg copper phthalocyanine powder. When the immobilized lipase was employed in the reaction system consisted of 1.5 mL hexanol and 1.5 mL vinyl acetate at 37℃ and 160 rpm, the conversion was five fold of that catalyzed by native lipase after 1 h, and reached 99.0% after 8 h. Undergoing six times of 8-h reuses, the immobilized lipase had an activity attenuation rate 1.22% h- 1, lower than 1.77% h- 1 of native lipase, which meant that the immobilized lipase was more stable. Even at the room temperature and the static state without shaking or stirring, the immobilized lipase could bring conversion 42.8% after 10 h and the native lipase gave 20.1%. Obviously, the immobilized lipase is an available biocatalyst in organic phase and has great potential in food industry.


Subject(s)
Burkholderia cepacia , Lipase/metabolism , Enzymes, Immobilized/metabolism , Esters , Esterification , Catalysis , Hexanols
4.
Bioprocess Biosyst Eng ; 45(3): 453-464, 2022 Mar.
Article in English | MEDLINE | ID: mdl-34686911

ABSTRACT

Citronellyl acetate as an important flavor, can be effectively synthesized by lipase catalysis in nonaqueous system. But lipases usually behave low catalytic activity due to aggregation and denaturation of them in organic phase. To enhance the nonaqueous catalysis, based on the mechanism of lipases activated at water/oil (organic phase) interface, the inexpensive race straw was processed into powder and filaments on which Pseudomonas fluorescens lipase was immobilized by physical adsorption, used for synthesis of citronellyl acetate via transesterification of citronellol and vinyl acetate. Results showed that the desired loading was 10 mg lipase immobilized on 30 mg rice straw filaments or 25 mg rice straw powder. When the two immobilized lipases were employed in the reaction system consisted of 1-mL citronellol and 2-mL vinyl acetate at 37 â„ƒ and 160 rpm, the conversions all reached 99.8% after 12 h. Under the reaction condition, the conversion catalyzed by 10 mg native lipase was 85.1%. Undergoing six times of 8-h reuses in the organic system, the filament and power immobilized lipases had weak activity attenuation rates 0.36 and 0.32% h-1, lower than 1.52% h-1 of native lipase. Even at the room temperature and the static state without shaking and stirring, the rice straw filaments immobilized lipase could brought conversion 62.9% after 10 h but the native lipase only gave 37.0%. Obviously, the rice straw, especially its filaments, is an inexpensive and available natural material to prepare immobilized lipase with desired catalysis in organic phase, meant significant potential in flavor industry.


Subject(s)
Oryza , Pseudomonas fluorescens , Catalysis , Enzymes, Immobilized/metabolism , Esterification , Lipase/metabolism , Monoterpenes , Oryza/metabolism , Pseudomonas fluorescens/metabolism
5.
J Clin Anesth ; 61: 109623, 2020 05.
Article in English | MEDLINE | ID: mdl-31672417

ABSTRACT

STUDY OBJECTIVE: To identify the efficacy and safety of haloperidol prophylaxis in adult patients with a high risk for delirium. DESIGN: A meta-analysis with trial sequential analysis of randomized controlled trials. INTERVENTION: A comprehensive search was performed in PubMed, the ISI Web of Knowledge, the Cochrane Library, and Embase databases from inception through to March 2019.Citation screening, data abstraction and quality assessment were performed in duplicate. Meta-analysis with trial sequential analysis (TSA) were used to assess the primary and secondary outcomes. In addition, we used the Grading of Recommendations Assessment Development and Evaluation (GRADE) to evaluate the certainty of the body of evidence. MAIN RESULTS: We appraised 8 RCTs involving 3034 patients that that were in compliance with inclusion and exclusion criterion. Pooled analyses indicated patients receiving haloperidol prophylaxis and placebo or normal saline did not significantly differ in incidence of delirium (relative risk [RR] = 0.90, 95% confidence interval [CI] = 0.70 to 1.15), with TSA inconclusive. Notably, compared with the control group, use of haloperidol significantly decreased the duration of delirium (Mean difference [MD] -0.94; 95% CI -1.82 to -0.06 days), with a marked heterogeneity. Additionally, haloperidol prophylaxis does not significantly affect duration of mechanical ventilation, length of intensive care unit (ICU) stay, length of hospital stay and mortality. In terms of safety profiles, haloperidol was not associated with increased risk for QTc prolongation, extrapyramidal symptoms, or adverse events. GRADE indicated the level of evidence was very low for a benefit from haloperidol prophylaxis. CONCLUSIONS: The results of our meta-analysis suggested the use of prophylactic haloperidol compared with placebo had no beneficial impacts on incidence of delirium, duration of mechanical ventilation, length of intensive care unit (ICU) stay, length of hospital stay and mortality in adult patients. It appeared to have a positive effect on duration of delirium, while with a significant heterogeneity. These findings do not support the routine usage of haloperidol for delirium prevention. TRIAL REGISTRATION: PROSPERO registration number: CRD42018100511. Registered on 17 July 2018.


Subject(s)
Delirium , Haloperidol , Adult , Delirium/epidemiology , Delirium/prevention & control , Haloperidol/adverse effects , Humans , Intensive Care Units , Length of Stay , Randomized Controlled Trials as Topic
6.
Medicine (Baltimore) ; 97(22): e10946, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29851838

ABSTRACT

RATIONALE: We report a man with amyopathic dermatomyositis (ADM) complicated by severe interstitial lung disease (ILD) received extracorporeal membrane oxygenation (ECMO) in combination with double filtration plasmapheresis (DFPP). This is the first report of the utility of ECMO in combination with DFPP in ADM related ILD in adults. PATIENT CONCERNS: A 48-year-old man who was previously healthy had a 2-month history of cough and shortness of breath, which aggravated in 5 days. DIAGNOSES: Amyopathic dermatomyositis and complicated by severe interstitial lung disease. INTERVENTIONS: ECMO was giving when the patient suffered acute respiratory failure. Though corticosteroids was giving, primary disease was still developing with relapses of spontaneous pneumomediastinum and pneumothorax. Then, DFPP treatment was initiated. OUTCOME: After the treatments above, the patient's clinical condition improved with the reduction of bilateral interstitial infiltrates and improvement of lung compliance. Unfortunately, he discontinued the treatment because of the financial problem. LESSONS: When get a rapid progressive interstitial lung disease for no apparent reason, amyopathic dermatomyositis should be considered, especially with suspected skin lesions. ECMO, in combination with DFPP, should be considered as a supportive therapy and initiated early in patients in acute respiratory failure secondary to ADM-ILD. Prompt initiation of DFPP in dermatomyositis patients with ILD might help reduce the occurrence of spontaneous pneumomediastinum or pneumothorax.


Subject(s)
Dermatomyositis/complications , Extracorporeal Membrane Oxygenation/methods , Lung Diseases, Interstitial/therapy , Plasmapheresis/methods , Combined Modality Therapy , Dermatomyositis/therapy , Glucocorticoids/therapeutic use , Humans , Lung Diseases, Interstitial/etiology , Male , Mediastinal Emphysema/etiology , Mediastinal Emphysema/therapy , Middle Aged , Pneumothorax/etiology , Pneumothorax/therapy
7.
Rev Sci Instrum ; 88(11): 113106, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29195355

ABSTRACT

Nowadays the utilization of aspheric lenses has become more and more popular, enabling highly increased degree of freedom for optical design and simultaneously improving the performance of optical systems. Fast and accurate surface profiling of these aspheric components is a real demand in characterization and optimization of the optical systems. In this paper, a novel and simple surface profiler instrument is designed and developed to fulfill the ever increasing need of testing the axially symmetric aspheric surface. The proposed instrument is implemented based on a unique mapping between the position and rotation angle of the reflective mirror in optical path and the coordinate of reflection point on the surface during rapid laser beam scanning. High accuracy of the proposed surface profiling method is ensured by a high-resolution grating guide rail, indexing plate, and position sensitive detector based on laser auto-collimation and beam center-fitting. Testing the meridian line of both convex and concave surfaces has been experimentally demonstrated using the developed instrument. In comparison to tested results from conventional image measuring instruments and coordinate measuring machines, coefficient of determination better than 0.999 99 and RMS less than 1.5 µm have been achieved, which validates the feasibility of this method. Analysis on the systematic error is beneficial to further improve its measurement accuracy. The presented instrument-essentially builds on the geometrical optics technique-provides a powerful tool to measure the aspheric surfaces quickly and accurately with stable structure and simple algorithm.

SELECTION OF CITATIONS
SEARCH DETAIL
...