High-Performance Liquid Chromatography Characterization and Identification of Antioxidant Polyphenols in Maple Syrup

Abstract

Maple syrup of four grades (extra-light, light, medium, and dark) of the 2007 crop was provided by three local (St. Joseph's Island, Ontario, Canada) producers. Twenty-four phenolic compounds were isolated from a medium-grade syrup and identified on the basis of spectral and chemical evidence. They were (a) benzoic acid and several hydroxylated and methoxylated derivatives (gallic acid, 1-O.-galloyl-β-d-glucose, γ-resorcylic acid); (b) cinnamic acid derivatives (p.-coumaric acid, 4-methoxycinnamic acid, caffeic acid, ferulic acid, sinapic acid, and the ester chlorogenic acid); (c) flavonoids, the flavanols catechin and epicatechin, and the flavonols kaempferol and its 3-O.-β-d-glucoside, 3-O.-β-d-galactoside, quercetin and its 3-O.-β-d-glucoside, 3-O.-β-L-rhamnoside and 3-O.-rhamnoglucoside (rutin). Traces obtained at 280 and 350 nm in HPLC runs of the ethyl acetate–soluble fractions of eight samples indicated the presence of many more phenolic substances, most at very low concentration with some varibilities in peak heights, but not in retention times, among the syrups. In view of the well-established antioxidant activity these substances possess, it is suggested that it is the complexity of the mixture rather than any one compound that may serve to counter the unhealthful presence of the high concentration of sugars in the syrup.     

Effets cardiovasculaires graves des chimiothérapies,thérapies ciblées et des traitements immunosuppresseurs

Survival of cancer patients has dramatically increased with the development of new treatments such as targeted therapies. Nevertheless, physicians now face new challenges as identifying and addressing treatment toxicities. While infection remains the leading cause of intensive care unit (ICU) admissions in these patients, various cardiovascular toxicities may occur during multiple lines of chemotherapy and targeted therapies, with progressively higher cumulative doses. Anthracyclines cardiotoxicity was identified in 1950 and has been extensively reported. More recently, multiple cardiovascular side effects of targeted therapies (monoclonal antibodies and tyrosine kinase inhibitors) have been described, including severe hypertension, cardiac failure, arrhythmia, myocardial ischemia, and pericardial effusion. In addition, the risk of both venous and arterial thromboembolic events is increased with the use of chemotherapy and targeted therapies, which can lead to ICU admission in the severe forms or because of bleeding events related to anticoagulation therapy. Microvascular endothelial cell injuries induced by cancer therapies or immunosuppressive agents may be responsible for thrombotic microangiopathy or posterior reversible encephalopathy syndrome. Finally, acute hypersensitivity reactions to chemotherapy or monoclonal antibodies can cause changes in blood pressure or anaphylactoid shock in the most severe cases. Critically ill cancer patients who experienced chemotherapy-related cardiovascular events require the same therapeutic approach to the cardiopathic patients. Maximal intensive care support is justified as most of these toxicities are potentially reversible.     

Are Covert Saccade Functionally Relevant in Vestibular Hypofunction?

The vestibulo-ocular reflex maintains gaze stabilization during angular or linear head accelerations, allowing adequate dynamic visual acuity. In case of bilateral vestibular hypofunction, patients use saccades to compensate for the reduced vestibulo-ocular reflex function, with covert saccades occurring even during the head displacement. In this study, we questioned whether covert saccades help maintain dynamic visual acuity, and evaluated which characteristic of these saccades are the most relevant to improve visual function. We prospectively included 18 patients with chronic bilateral vestibular hypofunction. Subjects underwent evaluation of dynamic visual acuity in the horizontal plane as well as video recording of their head and eye positions during horizontal head impulse tests in both directions (36 ears tested). Frequency, latency, consistency of covert saccade initiation, and gain of covert saccades as well as residual vestibulo-ocular reflex gain were calculated. We found no correlation between residual vestibulo-ocular reflex gain and dynamic visual acuity. Dynamic visual acuity performance was however positively correlated with the frequency and gain of covert saccades and negatively correlated with covert saccade latency. There was no correlation between consistency of covert saccade initiation and dynamic visual acuity. Even though gaze stabilization in space during covert saccades might be of very short duration, these refixation saccades seem to improve vision in patients with bilateral vestibular hypofunction during angular head impulses. These findings emphasize the need for specific rehabilitation technics that favor the triggering of covert saccades. The physiological origin of covert saccades is discussed.     

On the photodegradation of azithromycin,erythromycin and tylosin and their transformation products – A kinetic study

In this study, the photo-induced degradation of azithromycin (Azi), erythromycin (Ery) and tylosin (Tyl) was investigated. The three macrolides are regularly found in different kinds of water, and are thus considered a potential environmental risk. In search of efficient ways for elimination, the compounds were systematically irradiated with a polychromatic UVC light source emitting 185, 254 and discretely further up to 580 nm. Due to their specific structural features, the macrolides possess different optical absorption characteristics leading to photodegradation pathways with dissimilar kinetic properties. Hence, the photodegradation products and their kinetics were analyzed using high-performance liquid chromatography (HPLC) coupled to high-resolution time-of-flight mass spectrometry. Among the degradants, i.e. the products formed during UV irradiation, both sugar moieties and lactone macrocycles were observed. Applying a first order kinetic model, the half-life of Azi was determined as 1.0?3.7 min, that of Ery as 1.0?14.2 min depending on the reaction conditions. The two compounds possess much lower absorption cross-sections than Tyl, in particular at 254 nm. Their half-lives appeared at least three times higher than that of Tyl that has t_1/2 of 0.2?1.0 min. Based on quantum efficiency considerations, it was assumed that the degradation of Ery and Azi was mainly due to hydroxyl radical formation, which originated from water irradiation below 200 nm, whereas Tyl experienced predominantly photo induced degradation. The photodegradants of Azi exhibited half-lives of over 200 min, whereas most of the photo-products of Ery and Tyl showed half-lives of less than 10 min. Photodegradation processes were investigated at pH 3, pH 7 and pH 9 and in the presence of hydrogen peroxide. Both the educts and the photo-products were degraded more rapidly under neutral and acid conditions.     

The Rewards and Challenges of Becoming a Clinical Instructor

Frontline nurses working in the clinical area are a vital component to nursing education. Taking on the role of adjunct clinical instructor can be a rewarding way to increase one's own knowledge while performing the important task of educating the next generation of nurses.