Potato glycoalkaloids detection based on conductometric sensor coupled to butyryl cholinesterase

For the construction of a biosensor sensitive to some steroidal glycoalkaloids a conductometric planar electrode as a transducer and the horse serum butyryl cholinesterase (BuChE) as a biorecognition element have been used. It has been shown that α-solanine, α-chaconine and solanidine can be detected within the range of their concentrations from 0.2 to 100 mM depending on the type of steroidal alkaloid used. The detection limits were estimated to be 0.2 mM for chaconine and 0.5 mM for solanine/solanidine. The responses of the sensors developed were reproducible: the relative standard deviation was about 1.5 % and 5 % for intra- and inter-sensor responses, respectively. Moreover, one sensor with the immobilized enzyme can be used repeatedly (for at least 100 measurements) after a simple washing by buffer and can be stored at room temperature without substantial loss in activity of the immobilized enzyme not less than 1 month. It has been shown that all the analytes investigated inhibit reversibly and competitively the horse BuChE immobilized on the transducer surface. In assays, which combined α-solanine and α-chaconine, inhibition of BuChE was not additive. A possibility to apply the biosensor developed for the quantitative detection of the total steroidal alkaloids pool in foodstuffs and some biological samples is discussed.При створенні біосенсора, чутливого до стероїдних гліко­алкалоїдів, застосовано кондуктометричний планарний елект­род як перетворювач і бутирилхолінестеразу (БуХЕ) як чут­ливий елемент. Соланін, чаконін та соланідин визначали в діапазоні концентрацій 0,2—100 мкМ залежно від типу алка­лоїду. Мінімальні концентрації, які визначаються за допомо­гою біосенсора, становлять 0,2 мкМ для чаконіну та 0,5 мкМ для соланіну/соланідину. Відносні стандартні внутрішньо- та міжсенсорні похибки складали 1,5 та 5 % відповідно. Крім того, той самий сенсор з іммобілізованим ферментом після відмивання в буфері можна багаторазово використовувати (щонайменше 100 вимірів) та зберігати за кімнатної темпе­ратури без суттєвого зменшення активності іммобілізо­ваного ферменту протягом місяця. Доведено, що всі дослід­жені речовини конкурентно та оборотно пригнічують кінську БуХЕ, іммобілізовану на поверхні перетворювача. При до­слідженні спільної дії α-соланіну та α-чаконіну додаткового пригнічення БуХЕ не спостерігалося. Обговорюється мож­ливість застосування розробленого біосенсора для кількісного визначення загальної фракції стероїдних глікоалкалоїдів у хар­чових продуктах та деяких біологічних зразках.Для создания биосенсора, чувствительного к стероидным гликоалкалоидам, использовали кондуктометрический планарный электрод в качестве преобразователя и бутирилхолинэстеразу (БуХЭ) как чувствительный элемент. Соланин, чаконин и соланидин определяли в диапазоне концентраций 0,2–100 мкМ в зависимости от типа алкалоида. Минимально определяемая концентрация для чаконина – 0,2 мкМ, для соланина/соланидина – 0,5 мкМ. Относительные стандартные внутри- и межсенсорные ошибки составили 1,5 и 5 % соответственно. Кроме того, один и тот же сенсор с иммобилизованным ферментом после простого отмывания буфером можно мно­горазово использовать (по меньшей мере, 100 измерений) и хранить при комнатной температуре без значительной поте­ри активности иммобилизованного фермента в течение меся­ца. Показано, что исследуемые вещества конкурентно и обра­тимо ингибируют лошадиную БуХС, иммобилизованную на поверхности преобразователя. При исследовании совместного действия α-соланина и α-чаконина дополнительного ингибирования БуХЭ не наблюдалось. Обсуждается возможность при­менения разработанного биосенсора для количественного опре­деления общей фракции стероидных гликоалкалоидов в пищевых продуктах и некоторых биологических образцах

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

Improved risk stratification of patients with atrial fibrillation: an integrated GARFIELD-AF tool for the prediction of mortality, stroke and bleed in patients with and without anticoagulation.

OBJECTIVES: To provide an accurate, web-based tool for stratifying patients with atrial fibrillation to facilitate decisions on the potential benefits/risks of anticoagulation, based on mortality, stroke and bleeding risks. DESIGN: The new tool was developed, using stepwise regression, for all and then applied to lower risk patients. C-statistics were compared with CHA2DS2-VASc using 30-fold cross-validation to control for overfitting. External validation was undertaken in an independent dataset, Outcome Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF). PARTICIPANTS: Data from 39 898 patients enrolled in the prospective GARFIELD-AF registry provided the basis for deriving and validating an integrated risk tool to predict stroke risk, mortality and bleeding risk. RESULTS: The discriminatory value of the GARFIELD-AF risk model was superior to CHA2DS2-VASc for patients with or without anticoagulation. C-statistics (95% CI) for all-cause mortality, ischaemic stroke/systemic embolism and haemorrhagic stroke/major bleeding (treated patients) were: 0.77 (0.76 to 0.78), 0.69 (0.67 to 0.71) and 0.66 (0.62 to 0.69), respectively, for the GARFIELD-AF risk models, and 0.66 (0.64-0.67), 0.64 (0.61-0.66) and 0.64 (0.61-0.68), respectively, for CHA2DS2-VASc (or HAS-BLED for bleeding). In very low to low risk patients (CHA2DS2-VASc 0 or 1 (men) and 1 or 2 (women)), the CHA2DS2-VASc and HAS-BLED (for bleeding) scores offered weak discriminatory value for mortality, stroke/systemic embolism and major bleeding. C-statistics for the GARFIELD-AF risk tool were 0.69 (0.64 to 0.75), 0.65 (0.56 to 0.73) and 0.60 (0.47 to 0.73) for each end point, respectively, versus 0.50 (0.45 to 0.55), 0.59 (0.50 to 0.67) and 0.55 (0.53 to 0.56) for CHA2DS2-VASc (or HAS-BLED for bleeding). Upon validation in the ORBIT-AF population, C-statistics showed that the GARFIELD-AF risk tool was effective for predicting 1-year all-cause mortality using the full and simplified model for all-cause mortality: C-statistics 0.75 (0.73 to 0.77) and 0.75 (0.73 to 0.77), respectively, and for predicting for any stroke or systemic embolism over 1 year, C-statistics 0.68 (0.62 to 0.74). CONCLUSIONS: Performance of the GARFIELD-AF risk tool was superior to CHA2DS2-VASc in predicting stroke and mortality and superior to HAS-BLED for bleeding, overall and in lower risk patients. The GARFIELD-AF tool has the potential for incorporation in routine electronic systems, and for the first time, permits simultaneous evaluation of ischaemic stroke, mortality and bleeding risks. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier for GARFIELD-AF (NCT01090362) and for ORBIT-AF (NCT01165710)

Two-year outcomes of patients with newly diagnosed atrial fibrillation: results from GARFIELD-AF.

AIMS: The relationship between outcomes and time after diagnosis for patients with non-valvular atrial fibrillation (NVAF) is poorly defined, especially beyond the first year. METHODS AND RESULTS: GARFIELD-AF is an ongoing, global observational study of adults with newly diagnosed NVAF. Two-year outcomes of 17 162 patients prospectively enrolled in GARFIELD-AF were analysed in light of baseline characteristics, risk profiles for stroke/systemic embolism (SE), and antithrombotic therapy. The mean (standard deviation) age was 69.8 (11.4) years, 43.8% were women, and the mean CHA2DS2-VASc score was 3.3 (1.6); 60.8% of patients were prescribed anticoagulant therapy with/without antiplatelet (AP) therapy, 27.4% AP monotherapy, and 11.8% no antithrombotic therapy. At 2-year follow-up, all-cause mortality, stroke/SE, and major bleeding had occurred at a rate (95% confidence interval) of 3.83 (3.62; 4.05), 1.25 (1.13; 1.38), and 0.70 (0.62; 0.81) per 100 person-years, respectively. Rates for all three major events were highest during the first 4 months. Congestive heart failure, acute coronary syndromes, sudden/unwitnessed death, malignancy, respiratory failure, and infection/sepsis accounted for 65% of all known causes of death and strokes for <10%. Anticoagulant treatment was associated with a 35% lower risk of death. CONCLUSION: The most frequent of the three major outcome measures was death, whose most common causes are not known to be significantly influenced by anticoagulation. This suggests that a more comprehensive approach to the management of NVAF may be needed to improve outcome. This could include, in addition to anticoagulation, interventions targeting modifiable, cause-specific risk factors for death. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Implications of serial measurements of natriuretic peptides in heart failure: insights from BIOSTAT‐CHF

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Les capteurs électrochimiques microniques

Presently, two main factors influence the evolution of both chemical and electrochemical sensors. The first is the very strong demand in sensors from various fields of industry. The second is the intrusion of microelectronic technologies in their fabrication processes which lead to the new concept of miniaturized sensors. The advantages of such small sensors are discussed. The various technologies of miniaturization used in the fabrication of electrochemical sensors are reviewed as well as the various methods of sensitization employed to functionalize the microtransducers, especially the Field Effect Transistors (FET)

Potato glycoalkaloids detection based on conductometric sensor coupled to butyryl cholinesterase

For the construction of a biosensor sensitive to some steroidal glycoalkaloids a conductometric planar electrode as a transducer and the horse serum butyryl cholinesterase (BuChE) as a biorecognition element have been used. It has been shown that α-solanine, α-chaconine and solanidine can be detected within the range of their concentrations from 0.2 to 100 mM depending on the type of steroidal alkaloid used. The detection limits were estimated to be 0.2 mM for chaconine and 0.5 mM for solanine/solanidine. The responses of the sensors developed were reproducible: the relative standard deviation was about 1.5 % and 5 % for intra- and inter-sensor responses, respectively. Moreover, one sensor with the immobilized enzyme can be used repeatedly (for at least 100 measurements) after a simple washing by buffer and can be stored at room temperature without substantial loss in activity of the immobilized enzyme not less than 1 month. It has been shown that all the analytes investigated inhibit reversibly and competitively the horse BuChE immobilized on the transducer surface. In assays, which combined α-solanine and α-chaconine, inhibition of BuChE was not additive. A possibility to apply the biosensor developed for the quantitative detection of the total steroidal alkaloids pool in foodstuffs and some biological samples is discussed.При створенні біосенсора, чутливого до стероїдних гліко­алкалоїдів, застосовано кондуктометричний планарний елект­род як перетворювач і бутирилхолінестеразу (БуХЕ) як чут­ливий елемент. Соланін, чаконін та соланідин визначали в діапазоні концентрацій 0,2—100 мкМ залежно від типу алка­лоїду. Мінімальні концентрації, які визначаються за допомо­гою біосенсора, становлять 0,2 мкМ для чаконіну та 0,5 мкМ для соланіну/соланідину. Відносні стандартні внутрішньо- та міжсенсорні похибки складали 1,5 та 5 % відповідно. Крім того, той самий сенсор з іммобілізованим ферментом після відмивання в буфері можна багаторазово використовувати (щонайменше 100 вимірів) та зберігати за кімнатної темпе­ратури без суттєвого зменшення активності іммобілізо­ваного ферменту протягом місяця. Доведено, що всі дослід­жені речовини конкурентно та оборотно пригнічують кінську БуХЕ, іммобілізовану на поверхні перетворювача. При до­слідженні спільної дії α-соланіну та α-чаконіну додаткового пригнічення БуХЕ не спостерігалося. Обговорюється мож­ливість застосування розробленого біосенсора для кількісного визначення загальної фракції стероїдних глікоалкалоїдів у хар­чових продуктах та деяких біологічних зразках.Для создания биосенсора, чувствительного к стероидным гликоалкалоидам, использовали кондуктометрический планарный электрод в качестве преобразователя и бутирилхолинэстеразу (БуХЭ) как чувствительный элемент. Соланин, чаконин и соланидин определяли в диапазоне концентраций 0,2–100 мкМ в зависимости от типа алкалоида. Минимально определяемая концентрация для чаконина – 0,2 мкМ, для соланина/соланидина – 0,5 мкМ. Относительные стандартные внутри- и межсенсорные ошибки составили 1,5 и 5 % соответственно. Кроме того, один и тот же сенсор с иммобилизованным ферментом после простого отмывания буфером можно мно­горазово использовать (по меньшей мере, 100 измерений) и хранить при комнатной температуре без значительной поте­ри активности иммобилизованного фермента в течение меся­ца. Показано, что исследуемые вещества конкурентно и обра­тимо ингибируют лошадиную БуХС, иммобилизованную на поверхности преобразователя. При исследовании совместного действия α-соланина и α-чаконина дополнительного ингибирования БуХЭ не наблюдалось. Обсуждается возможность при­менения разработанного биосенсора для количественного опре­деления общей фракции стероидных гликоалкалоидов в пищевых продуктах и некоторых биологических образцах