This work presents a framework for evaluating hybrid nanoflowers using
lipase. It was expanded on previous findings by testing lipase hybrid nanoflowers (hNF-lipase) formation over a wide range of pH ...values (5-9) and buffer concentrations (10-100 mM). The free enzyme activity was compared with that of hNF-lipase. The analysis, performed by molecular docking, described the effect of lipase interaction with copper ions. The morphological characterization of hNF-lipase was performed using scanning electron microscopy. Fourier Transform Infrared Spectroscopy performed the physical-chemical characterization. The results show that all hNF-lipase activity presented values higher than that of the free enzyme. Activity is higher at pH 7.4 and has the highest buffer concentration of 100 mM. Molecular docking analysis has been used to understand the effect of enzyme protonation on hNF-lipase formation and identify the main the main binding sites of the enzyme with copper ions. The hNF-lipase nanostructures show the shape of flowers in their micrographs from pH 6 to 8. The spectra of the nanoflowers present peaks typical of the amide regions I and II, current in lipase, and areas with P-O vibrations, confirming the presence of the phosphate group. Therefore, hNF-lipase is an efficient biocatalyst with increased catalytic activity, good nanostructure formation, and improved stability.
Design of ionic liquids for lipase purification Ventura, Sónia P.M.; Sousa, Sílvia G.; Freire, Mara G. ...
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences,
09/2011, Letnik:
879, Številka:
26
Journal Article
Recenzirano
Aqueous two-phase systems (ATPS) are considered as efficient downstream processing techniques in the production and purification of enzymes, since they can be considered harmless to biomolecules due ...to their high water content and due to the possibility of maintaining a neutral pH value in the medium. A recent type of alternative ATPS is based on hydrophilic ionic liquids (ILs) and salting-out inducing salts. The aim of this work was to study the lipase (
Candida antarctica lipase B – CaLB) partitioning in several ATPS composed of ionic liquids (ILs) and inorganic salts, and to identify the best IL for the enzyme purification. For that purpose a wide range of IL cations and anions, and some of their combinations were studied. For each system the enzyme partitioning between the two phases was measured and the purification factors and enzyme recoveries were determined. The results indicate that the lipase maximum purification and recovery were obtained for cations with a C
8 side alkyl chain, the N(CN)
2 anion and ILs belonging to the pyridinium family. However, the highest purification parameters were observed for 1-methyl-3-octylimidazolium chloride C
8mimCl, suggesting that the IL extraction capability does not result from a cumulative character of the individual characteristics of ILs. The results indicate that the IL based ATPS have an improved performance in the lipase purification and recovery.
Background
It is unclear whether thoracic aortic volume (TAV) is useful for cardiovascular (CV) disease prognosis and risk assessment.
Purpose
This study evaluated cross‐sectional associations of TAV ...with CV risk factors, and longitudinal association with incident CV events in the multiethnic study of atherosclerosis.
Study Type
Retrospective cohort analysis of prospective data.
Population
1182 participants (69 ± 9 years, 54% female, 37% Caucasian, 18% Chinese, 31% African American, 14% Hispanic, 60% hypertensive, and 20% diabetic) without prior CV disease.
Field Strength and sequences
Axial black‐blood turbo spin echo or bright blood steady‐state free precession images on 1.5T scanners.
Assessment
TAV was calculated using Simpson's method from axial images, and included the ascending arch and descending segments. Traditional CV risk factors were assessed at the time of MRI. CV outcomes over a 9‐year follow‐up period were recorded and represented a composite of stroke, stroke death, coronary heart disease (CHD), CHD death, atherosclerotic death, and CVD death.
Statistical Tests
Multivariable linear regression models adjusted for height and weight were used to determine the relationship (β coefficient) between TAV and CV risk factors. Cox regression models assessed the association of TAV and incident CV events. A P‐value of <0.05 was deemed statistically significant.
Results
Mean TAV was = 139 ± 41 mL. In multivariable regression, TAV was directly associated with age (β = 1.6), male gender (β = 23.9), systolic blood pressure (β = 0.1), and hypertension medication use (β = 7.9); and inversely associated with lipid medication use (β = −5.3) and treated diabetes (β = −8.9). Compared to Caucasians, Chinese Americans had higher TAV (β = 11.4), while African Americans had lower TAV (β = −7.0). Higher TAV was independently associated with incident CV events (HR: 1.057 per 10 mL).
Conclusion
Greater TAV is associated with incident CV events, increased age, and hypertension in a large multiethnic population while treated diabetes and lipid medication use were associated with lower TAV.
Level of Evidence
2
Technical Efficacy
Stage 2
The association of longitudinal changes in left ventricular (LV) structure and function with myocardial fibrosis is unclear. We relate temporal changes in body size-indexed LV mass (LVMi) and ...end-diastolic volume indexed to body surface area, LV mass-to-volume ratio, and LV ejection fraction (LVEF) from cine cardiac magnetic resonance for 10 years, with replacement scar assessed from late gadolinium enhancement, and lower postcontrast T1 times reflecting greater diffuse myocardial fibrosis measured at the end of the follow-up period. All participants (n=1813) who underwent cardiac magnetic resonance twice as part of the Multi-Ethnic Study of Atherosclerosis 10 years apart were included. Multivariable logistic and linear regression models adjusted for cardiovascular risk factors measured the association of 10-year changes in LV structure and function, with fibrosis measured at follow-up. The presence of LV scar at year 10 was cross-sectionally associated with higher LVMi (≈10 g/m(2)), higher mass-to-volume ratio (0.1-0.2 g/mL), but lower LVEF (≈4%) and longitudinally with 3% decrease in LVEF and 0.7% greater end-diastolic volume indexed to body surface area in men for 10 years. Lower postcontrast T1 times at year 10 were associated cross-sectionally with lower LVMi (r=0.33), end-diastolic volume indexed to body surface area (r=0.25), and LVEF (in men only: r=0.14) and longitudinally with a decrease in LVMi (r=0.20) and reduction in LVEF (in men only: r=0.15). Sustained hypertension for 10 years was associated with increased LVMi and higher diffuse and replacement fibrosis at follow-up. During a 10-year period, increased concentric hypertrophy in women and LV dilatation in men were associated with replacement fibrosis, whereas decreasing LVMi was associated with diffuse fibrosis. Hypertension-induced remodeling was related to enhanced replacement and diffuse fibrosis, as well as hypertrophy.
Purpose To compare the prognostic importance (time to major adverse cardiovascular event MACE) of combined computed tomography (CT) angiography and CT myocardial stress perfusion imaging with that of ...combined invasive coronary angiography (ICA) and stress single photon emission CT myocardial perfusion imaging. Materials and Methods This study was approved by all institutional review boards, and written informed consent was obtained. Between November 2009 and July 2011, 381 participants clinically referred for ICA and aged 45-85 years were enrolled in the Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) prospective multicenter diagnostic study. All images were analyzed in blinded independent core laboratories, and a panel of physicians adjudicated all adverse events. MACE was defined as revascularization (>30 days after index ICA), myocardial infarction, or cardiac death; hospitalization for chest pain or congestive heart failure; or arrhythmia. Late MACE was defined similarly, except for patients who underwent revascularization within the first 182 days after ICA, who were excluded. Comparisons of 2-year survival (time to MACE) used standard Kaplan-Meier curves and restricted mean survival times bootstrapped with 2000 replicates. Results An MACE (49 revascularizations, five myocardial infarctions, one cardiac death, nine hospitalizations for chest pain or congestive heart failure, and one arrhythmia) occurred in 51 of 379 patients (13.5%). The 2-year MACE-free rates for combined CT angiography and CT perfusion findings were 94% negative for coronary artery disease (CAD) versus 82% positive for CAD and were similar to combined ICA and single photon emission CT findings (93% negative for CAD vs 77% positive for CAD, P < .001 for both). Event-free rates for CT angiography and CT perfusion versus ICA and single photon emission CT for either positive or negative results were not significantly different for MACE or late MACE (P > .05 for all). The area under the receiver operating characteristic curve (AUC) for combined CT angiography and CT perfusion (AUC = 68; 95% confidence interval CI: 62, 75) was similar (P = .36) to that for combined ICA and single photon emission CT (AUC = 71; 95% CI: 65, 79) in the identification of MACE at 2-year follow-up. Conclusion Combined CT angiography and CT perfusion enables similar prediction of 2-year MACE, late MACE, and event-free survival similar to that enabled by ICA and single photon emission CT.
RSNA, 2017 Online supplemental material is available for this article.
We investigated the association of cardiovascular risk factors and myocardial fibrosis with early cardiac dysfunction in type 1 diabetes.
Participants with type 1 diabetes aged 13-39 years without a ...known history of cardiovascular disease (CVD) (
= 1,441) were recruited into the Diabetes Control and Complications Trial (1983-1993) and subsequently followed in the Epidemiology of Diabetes Interventions and Complications study (1994 to present). Seven hundred fourteen participants underwent cardiac magnetic resonance (CMR) imaging (2007-2009) with late gadolinium enhancement sequences to assess ischemic and nonischemic scars and tagging sequences to evaluate circumferential strain. CMR-derived T1 mapping also was used to assess interstitial fibrosis. The influence of cardiovascular risk factors and myocardial scar on circumferential strain was assessed using linear regression.
Circumferential dysfunction was consistently associated with older age, male sex, smoking history, obesity, higher blood pressure, lower HDL cholesterol, and higher mean HbA
. Participants with nonischemic scars (
= 16) had the worst circumferential function compared with those without scars (β ± SE 1.32 ± 0.60;
= 0.03). In sex-adjusted models, the correlation between T1 times and circumferential strain was not significant. In the fully adjusted models, a trend toward circumferential dysfunction in participants with nonischemic scars was found. Left ventricular ejection fraction was not associated with risk factors but was significantly lower if a myocardial scar was present.
Traditional CVD risk factors and elevated HbA
levels are major factors related to early cardiac dysfunction in type 1 diabetes. Nonischemic myocardial scar, possibly as a marker of chronic exposure to known risk factors, may predict early cardiac dysfunction mediated by diffuse myocardial fibrosis as seen in diabetic cardiomyopathy.
To identify an accurate and reproducible method to define myocardial infarct (MI) size, we conducted a study in a closed-chest canine model of acute myocardial infarction, in which MI size was ...measured using different thresholding techniques and by imaging at different delay times after contrast administration.
The MI size by contrast-enhanced magnetic resonance imaging (CE-MRI) is directly related to long-term prognosis. However, previous measurements were done using nonuniform methods and tended to overestimate nonviable areas.
Thirteen animals underwent 90 min of coronary artery occlusion, followed by reperfusion. The CE-MRI data were acquired within 24 h after reperfusion and compared with triphenyltetrazolium chloride pathology. In the first nine animals, images were obtained ∼15 min after gadolinium diethylene triamine penta-acetic acid (Gd-DTPA) using an inversion-recovery gradient-echo pulse sequence. To identify the most accurate method, MI size by CE-MRI was measured visually and by semi-automatic thresholding techniques, using different criteria. In four additional animals, images were acquired every 6 min until 30 min after Gd-DTPA.
Postmortem MI size was 13.5 ± 2.6% of left ventricular volume. Semi-automatic techniques, using full-width at half-maximum (FWHM) criterion, correlated best with postmortem data (r2= 0.94, p < 0.001; results confirmed by Bland-Altman plots). Using FWHM, there was no difference in MI size between different delay times after contrast (15.2 ± 2.9% to 14.5 ± 4.2% at 6 and 30 min, respectively; p = NS).
When an objective technique is used to define MI size by CE-MRI, accurate infarct size measurements can be obtained from images obtained up to 30 min after contrast administration.
We evaluated the role of myocardial delayed-enhancement (MDE) magnetic resonance imaging (MRI) for noninvasive detection of fibrosis in Arrhythmogenic right ventricular dysplasia/cardiomyopathy ...(ARVD/C).
Arrhythmogenic right ventricular dysplasia/cardiomyopathy is characterized by fibro-fatty replacement of the right ventricle (RV) leading to arrhythmias and RV failure. Endomyocardial biopsy can demonstrate fibro-fatty replacement of the RV myocardium; however, the test is invasive and carries a risk of perforation.
Thirty consecutive patients were prospectively evaluated for ARVD/C. Magnetic resonance imaging was performed on a 1.5-T scanner. Ten minutes after intravenous administration of 0.2 mmol/kg of gadodiamide, MDE-MRI was obtained. Diagnosis of ARVD/C was based upon the Task Force criteria and did not include MRI findings.
Twelve (40%) of 30 patients met the Task Force criteria for ARVD/C. Eight (67%) of the 12 ARVD/C patients demonstrated increased signal on MDE-MRI in the RV compared with none (0%) of the 18 patients without ARVD/C (p < 0.001). Endomyocardial biopsy was performed in 9 of the 12 ARVD/C patients. Of the nine patients, four had fibro-fatty changes consistent with the diagnosis of ARVD/C. Each of these patients had increased RV signal on MDE-MRI. None of the patients without ARVD/C had any abnormalities either on histopathology or on MDE-MRI. Electrophysiologic testing revealed inducible sustained ventricular tachycardia (VT) in six of the eight ARVD/C patients with delayed enhancement, compared with none of the ARVD/C patients without delayed enhancement (p = 0.01).
Noninvasive detection of RV myocardial fibro-fatty changes in ARVD/C is possible by MDE-MRI. Magnetic resonance imaging findings had an excellent correlation with histopathology and predicted inducible VT on programmed electrical stimulation, suggesting a possible role in evaluation and diagnosis of patients with suspected ARVD/C.
The goal of this study was to assess the association between left atrial (LA) volume and function measured with feature-tracking cardiac magnetic resonance (CMR) and development of heart failure (HF) ...in asymptomatic individuals.
Whether alterations of LA structure and function precede or follow HF development remains incompletely understood. We hypothesized that significant alterations of LA deformation and architecture precede the development of HF in the general population.
In a case-control study nested in MESA (Multi-Ethnic Study of Atherosclerosis), baseline LA volume and function assessed using CMR feature-tracking were compared between 112 participants with incident HF (mean age 68.4 ± 8.2 years; 66% men) and 224 age- and sex-matched controls (mean age 67.7 ± 8.9 years; 66% men). Participants were followed up for 8 years. All individuals were in normal sinus rhythm at the time of imaging, without any significant valvular abnormalities and free of clinical cardiovascular diseases.
Individuals with incident HF had greater maximal and minimal LA volume indexes (LAVImin) than control subjects (40 ± 13 mm(3)/m(2) vs. 33 ± 10 mm(3)/m(2) p <0.001 for maximal LA index and 25 ± 11 mm(3)/m(2) vs. 17 ± 7 mm(3)/m(2) p <0.001 for LAVImin). The HF case subjects also had smaller global peak longitudinal atrial strain (PLAS) (25 ± 11% vs. 38 ± 16%; p <0.001) and lower LA emptying fraction (40 ± 11% vs. 48 ± 9%; p <0.001) at baseline. After adjustment for traditional cardiovascular risk factors, left ventricular mass, and N-terminal pro-B-type natriuretic peptide, global PLAS (odds ratio: 0.36 per SD 95% confidence interval: 0.22 to 0.60) and LAVImin (odds ratio: 1.65 per SD 95% confidence interval: 1.04 to 2.63) were independently associated with incident HF.
Deteriorations in LA structure and function preceded development of HF. Lower global PLAS and higher LAVImin, measured using CMR feature-tracking, were independent markers of incident HF in a multiethnic population of asymptomatic individuals.
This study sought to examine the association between left ventricular hypertrophy (LVH), defined by cardiac magnetic resonance (CMR) and electrocardiography (ECG), with incident atrial fibrillation ...(AF).
Previous studies of the association between AF and LVH were based primarily on echocardiographic measures of LVH.
The MESA (Multi-Ethnic Study of Atherosclerosis) enrolled 4,942 participants free of clinically recognized cardiovascular disease. Incident AF was based on MESA-ascertained hospital-discharge International Classification of Diseases codes and Centers for Medicare and Medicaid Services inpatient hospital claims. CMR-LVH was defined as left ventricular mass ≥95th percentile of the MESA population distribution. Eleven ECG-LVH criteria were assessed. The association of LVH with incident AF was evaluated using multivariable Cox proportional hazards models adjusted for CVD risk factors.
During a median follow-up of 6.9 years, 214 incident AF events were documented. Participants with AF were more likely to be older, hypertensive, and overweight. The risk of AF was greater in participants with CMR-derived LVH (hazard ratio HR: 2.04, 95% confidence interval CI: 1.15 to 3.62). AF was associated with ECG-derived LVH measure of Sokolow-Lyon voltage product after adjusting for CMR-LVH (HR: 1.83, 95% CI: 1.06 to 3.14, p = 0.02). The associations with AF for CMR-LVH and Sokolow-Lyon voltage product were attenuated when adjusted for CMR left atrial volumes.
In a multiethnic cohort of participants without clinically detected cardiovascular disease, both CMR and ECG-derived LVH were associated with incident AF. ECG-LVH showed prognostic significance independent of CMR-LVH. The association was attenuated when adjusted for CMR left atrial volumes.
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