108 research outputs found
Microplastics Generation: Onset of Fragmentation of Polyethylene Films in Marine Environment Mesocosms
No full textThe fragmentation of high-density polyethylene (HDPE) films from single-use supermarket plastic bags to microplastics under laboratory-simulated onshore and nearshore conditions was investigated for a period of 6 months. The weathering process of the plastic strips either on beach sand or in seawater under direct natural sunlight was monitored by tensile strength, molecular weight measurements, FTIR, weight loss, and image processing of photographs of the plastic strips before and after mild mechanical stress was applied. The latter represents a novel method proposed for determining the onset of fragmentation through the application of mild mechanical stress on the weathered plastic samples emulating the action of sand and wind on a beach. It was found that 12 h of application of mild mechanical stress in rotating glass bottles filled partially with sand was sufficient time to reach the maximum degree of fragmentation that could occur for the weathered plastics samples being tested. For example, applied mechanical stress yielded an area loss of almost 14% for samples weathered for a period of 5 months and about 16.7% after 5.5 months. While tensile strength tests and molecular weight measurements were rather inconclusive till the very last month when the onset of fragmentation was identified; FTIR measurements revealed that samples under ultraviolet irradiation were gradually modified chemically until fragmentation commenced. After 6 months of weathering, molecular weight measurements showed a 60% reduction for sample SMB-1 whereas for sample SMB-2 the measurement was not possible due to extensive fragmentation. The onset of fragmentation for SMB-1 and SMB-2 samples occurred at a cumulative luminance of 5.3 à 106luxâ¢d and in the presence of atmospheric oxygen whereby the polymer films broke down partially to microplastics. When the UV exposure reached 7.2 à 106luxâ¢d the weathered plastic strips broke down fully to microplastics with the application of a mild mechanical stress. Samples placed in seawater proved to be resistant to fragmentation compared to those on sand over the 6-month period of the weathering experiment. The direct implication of this work is that beached macroplastic debris should be regularly collected from the seashore before they are weathered by sunlight and returned to the sea as microplastics by the action of high waves or strong winds
Is there any true distinction in extreme dipping versus nondipping or dipping phenotype regarding hypertension-mediated organ damage in newly diagnosed and never-treated hypertensive patients?
No full textDipping phenomena is defined as nocturnal BP fall >10% during 24-h ambulatory blood pressure (BP) monitoring (ABPM) which carries a favorable cardiovascular risk (CVR) prognosis due to reduced 24-h hypertension burden. To date, extreme dipping phenotype (defined as BP decrease ≥20%) has led to controversial prognostic results regarding CVR. We aimed to explore hypertension-mediated organ damage (HMOD) in extreme dippers compared to the other dipping phenotypes (nondipping, dipping). From 490 consecutive patients with newly diagnosed never-treated arterial hypertension (mean age 51 ± 11 years, 294 males) subjected to 24-h ABPM, we studied 52 extreme dippers, 52 age- and gender-matched nondippers, and 52 age- and gender-matched dippers. All patients were subjected to arterial stiffness (PWV), 24-h microalbumin levels, carotid intima-media thickness (cIMT), diastolic dysfunction (E/Ea), and left ventricular mass index (LVMI) evaluation. ANOVA analysis found no differences regarding HMOD between groups. Multiple regression analysis revealed the following independent direct relationships between: (i) office SBP and PWV in nondippers (β = 0.35, p = 0.01) and extreme dippers (β = 0.49, p < 0.001), (ii) office SBP and E/Ea in extreme dippers (β = 0.39, p = 0.007), (iii) 24-h diurnal and nocturnal SBP and E/Ea in dippers (β = 0.40, p = 0.004, β = 0.39, p = 0.005, and β = 0.40, p = 0.004, respectively), and (iv) 24-h and nocturnal SBP and LVMI in nondippers (β = 0.29, p = 0.04 and β = 0.36, p = 0.009, respectively). In the early phases of untreated-arterial hypertension disease, extreme dipping phenotype in middle-aged hypertensives does not imply an adverse or favorable prognosis regarding the incidence of HMOD either as continuous variables or as abnormal HMOD compared to other dipping phenotypes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited part of Springer Nature
Οργανοκαταλυτικοί Οξειδωτικοί Μετασχηματισμοί Φιλικοί προς το Περιβάλλον
No full textΗ Οργανοκατάλυση αποτελεί έναν σύγχρονο και φιλικό προς το περιβάλλον τομέα κατάλυσης. Βάσει του οξειδωτικού πρωτοκόλλου που θεσπίστηκε από το Εργαστήριο Οργανικής Χημείας του Εθνικού και Καποδιστριακού Πανεπιστημίου Αθηνών, χρησιμοποιώντας το υπεροξείδιο του υδρογόνου ως οξειδωτικό και την 2,2,2-τριφθορομέθυλο ακετοφαινόνη ως καταλύτη για την ενεργοποίηση του οξειδωτικού, στην παρούσα διατριβή μελετήθηκε η χρήση της συγκεκριμένης μεθόδου για την ανάπτυξη one-pot αντιδράσεων με σκοπό: • Τη σύνθεση ισοξαζολινών μέσω οξείδωσης αλλυλο-οξιμών. • Τη βελτιστοποίηση συνθηκών της εκλεκτικής οξείδωσης σουλφιδίων σε σουλφοξείδια ή σουλφόνες. • Τη σύνθεση διϋδροξυ-βενζοφουρανίων μέσω οξείδωσης αλλυλο-φαινολών. • Τη σύνθεση λακτονών μέσω οξείδωσης αλκενυλο-οξέων. Επίσης, μελετήθηκαν φωτοχημικές αντιδράσεις, στις οποίες με τη χρήση μεταλλικών συμπλόκων ως καταλύτες και οικιακών λαμπτήρων ως πηγή ενέργειας επετεύχθη: • Η σύνθεση λακτονών από αλκένια και ιωδο-οξικό οξύ και η μελέτη του μηχανισμού της αντίδρασης με τη χρήση Φασματομετρίας Μάζας Υψηλής Διακριτικής Ικανότητας (HRMS). • H σύνθεση ενώσεων που φέρουν κυανο-ομάδα από αλκένια και βρωμο-ακετονιτρίλιο. Τέλος, μελετήθηκε η σύνθεση λακτονών από κετο-οξέα με χρήση της εποξείδωσης Corey-Chaykovsky.Organocatalysis constitutes a new and environmentally friendly field in Organic Chemistry. Based on oxidant protocol that established from Laboratory of Organic Chemistry of the National and Kapodistrian University of Athens, utilizing hydrogen peroxide as the oxidant and 2,2,2-trifluoromethylacetophenone as the catalyst for oxidant’s activation, in the present thesis studied the application of this method for the achievement of one-pot reactions, in order to: • Synthesize isoxazolines by oxidation of allyl-oximes. • Optimize of the reaction conditions for the selective oxidation of sulfides to sulfoxides or sulfones. • Synthesize dihydrobenzofurans by oxidation of allylphenols. • Synthesize lactones by oxidation of alkenoic acids. Furthermore, a variety of photochemical reactions have been studied, utilizing metal-complexes as the catalysts and house lamps as the energy source. Analytically, we achieved: • The synthesis of lactones from alkenes and iodo-acetic acid. The reaction mechanis have been studied extensively with High Resolution Mass Spectroscopy (HRMS). • The synthesis of compounds with cyano-moiety from alkenes and bromoacetonitrile. Finally, we studied the synthesis of lactones from keto-acids via the Corey-Chaykovsky epoxidation
Angiotensin II induces soluble fms-Like tyrosine kinase-1 release via calcineurin signaling pathway in pregnancy
No full textMaternal endothelial dysfunction in preeclampsia is associated with increased soluble fms-like tyrosine kinase-1 (sFlt-1), a circulating antagonist of vascular endothelial growth factor and placental growth factor. Angiotensin II (Ang II) is a potent vasoconstrictor that increases concomitant with sFlt-1 during pregnancy. Therefore, we speculated that Ang II may promote the expression of sFlt-1 in pregnancy. Here we report that infusion of Ang II significantly increases circulating levels of sFlt-1 in pregnant mice, thereby demonstrating that Ang II is a regulator of sFlt-1 secretion in vivo. Furthermore, Ang II stimulated sFlt-1 production in a dose- and time-dependent manner from human villous explants and cultured trophoblasts but not from endothelial cells, suggesting that trophoblasts are the primary source of sFlt-1 during pregnancy. As expected, Ang II-induced sFlt-1 secretion resulted in the inhibition of endothelial cell migration and in vitro tube formation. In vitro and in vivo studies with losartan, small interfering RNA specific for calcineurin and FK506 demonstrated that Ang II-mediated sFlt-1 release was via Ang II type 1 receptor activation and calcineurin signaling, respectively. These findings reveal a previously unrecognized regulatory role for Ang II on sFlt-1 expression in murine and human pregnancy and suggest that elevated sFlt-1 levels in preeclampsia may be caused by a dysregulation of the local renin/angiotensin system
Hypertension-mediated organ damage regression associates with blood pressure variability improvement three years after successful treatment initiation in essential hypertension
No full textBlood pressure variability (BPV) has been associated with the development, progression, and severity of cardiovascular (CV) organ damage and an increased risk of CV morbidity and mortality. We aimed to explore any association between short-term BPV reduction and hypertension-mediated organ damage (HMOD) regression in hypertensive patients 3-year post-treatment initiation regarding BP control. 24-h ambulatory blood pressure monitoring (24 h ABPM) was performed at baseline in 180 newly diagnosed and never-treated hypertensive patients. We measured 24 h average systolic (24 h SBP) and diastolic BP (24 h DBP) as well as 24 h systolic (sBPV) and diastolic BPV (dBPV). Patients were initially evaluated and 3 years later regarding arterial stiffness (PWV), left ventricular hypertrophy (LVMI), carotid intima-media thickness (cIMT), 24 h microalbumin levels (MAU), and coronary flow reserve (CFR). Successful BP treatment was defined as 24 h SBP/DBP < 130/80 mm Hg based on 2nd ABPM and subsequently, patients were characterized as controlled (n = 119, age = 53 ± 11 years) or non-controlled (n = 61, age = 47 ± 11 years) regarding their BP levels. In the whole population and the controlled group, 24 h SBP/DBP, sBPV/dBPV, LVMI, and IMT were decreased. Additionally, LVMI improvement was related with both sBPV (p <.001) and dBPV reduction (r =.18, p =.02 and r =.20, p =.03, respectively). In non-controlled hypertensives, PWV was increased. In multiple linear regression analysis, sBPV and dBPV reduction predicted LVMI improvement in total population and controlled group independently of initial office SBP, mean BP, and 24 h-SBP levels. In middle-aged hypertensive patients, a 3-year antihypertensive treatment within normal BP limits, confirmed by 24-h ABPM, leads to CV risk reduction associated with sBPV and dBPV improvement. © 2021 The Authors. The Journal of Clinical Hypertension published by Wiley Periodicals LLC
Organocatalytic oxidative environmentally friendly transformations
No full textOrganocatalysis constitutes a new and environmentally friendly field in Organic Chemistry. Based on oxidant protocol that established from Laboratory of Organic Chemistry of the National and Kapodistrian University of Athens, utilizing hydrogen peroxide as the oxidant and 2,2,2-trifluoromethylacetophenone as the catalyst for oxidant’s activation, in the present thesis studied the application of this method for the achievement of one-pot reactions, in order to: Synthesize isoxazolines by oxidation of allyl-oximes. Optimize of the reaction conditions for the selective oxidation of sulfides to sulfoxides or sulfones. Synthesize dihydrobenzofurans by oxidation of allylphenols. Synthesize lactones by oxidation of alkenoic acids.Furthermore, a variety of photochemical reactions have been studied, utilizing metal-complexes as the catalysts and house lamps as the energy source. Analytically, we achieved: The synthesis of lactones from alkenes and iodo-acetic acid. The reaction mechanis have been studied extensively with High Resolution Mass Spectroscopy (HRMS). The synthesis of compounds with cyano-moiety from alkenes and bromoacetonitrile.Finally, we studied the synthesis of lactones from keto-acids via the Corey-Chaykovsky epoxidation.Η Οργανοκατάλυση αποτελεί έναν σύγχρονο και φιλικό προς το περιβάλλον τομέα κατάλυσης. Βάσει του οξειδωτικού πρωτοκόλλου που θεσπίστηκε από το Εργαστήριο Οργανικής Χημείας του Εθνικού και Καποδιστριακού Πανεπιστημίου Αθηνών, χρησιμοποιώντας το υπεροξείδιο του υδρογόνου ως οξειδωτικό και την 2,2,2-τριφθορομέθυλο ακετοφαινόνη ως καταλύτη για την ενεργοποίηση του οξειδωτικού, στην παρούσα διατριβή μελετήθηκε η χρήση της συγκεκριμένης μεθόδου για την ανάπτυξη one-pot αντιδράσεων με σκοπό: Τη σύνθεση ισοξαζολινών μέσω οξείδωσης αλλυλο-οξιμών. Τη βελτιστοποίηση συνθηκών της εκλεκτικής οξείδωσης σουλφιδίων σε σουλφοξείδια ή σουλφόνες. Τη σύνθεση διϋδροξυ-βενζοφουρανίων μέσω οξείδωσης αλλυλο-φαινολών. Τη σύνθεση λακτονών μέσω οξείδωσης αλκενυλο-οξέων.Επίσης, μελετήθηκαν φωτοχημικές αντιδράσεις, στις οποίες με τη χρήση μεταλλικών συμπλόκων ως καταλύτες και οικιακών λαμπτήρων ως πηγή ενέργειας επετεύχθη: Η σύνθεση λακτονών από αλκένια και ιωδο-οξικό οξύ και η μελέτη του μηχανισμού της αντίδρασης με τη χρήση Φασματομετρίας Μάζας Υψηλής Διακριτικής Ικανότητας (HRMS). H σύνθεση ενώσεων που φέρουν κυανο-ομάδα από αλκένια και βρωμο-ακετονιτρίλιο.Τέλος, μελετήθηκε η σύνθεση λακτονών από κετο-οξέα με χρήση της εποξείδωσης Corey-Chaykovsky
Infiltration of the sphenopalatine ganglion decreases blood pressure in newly diagnosed and never treated patients with essential hypertension
No full textBackground Sphenopalatine ganglion (SPG), an extracranial structure, is connected with the central nervous system (CNS) through sympathetic and parasympathetic nerves. We hypothesized that SPG block through sympathetic nerves anesthesia might decrease blood pressure (BP) in recently diagnosed and never treated middle-aged patients with essential hypertension. Methods We performed SBG block in 22 hypertensive patients (mean age 45 ± 12 years, 15 men). All patients have been subjected to 24 hour ambulatory blood pressure monitoring a week prior the procedure as well as in a period of 21–30 days after the SBG block in order to estimate differences in 24 h average systolic (24 h SBP) and diastolic blood pressure (24 h DBP), daytime, nighttime, pre-awake and early morning SBP and DBP as well as BP load. Results We found that 24 h SBP (p = 0.001) and 24 h DBP (p < 0.001), daytime SBP and DBP (p < 0.001) as well as daytime SBP and DBP load (p = 0.002 and p < 0.001, respectively) were decreased in total population at 21–30 days after SPG block. In 11/22 responders (24 h SBP decrease ≥ 5 mm Hg), SBP and DBP were reduced during overall 24 h and daytime (p < 0.001) and nighttime periods (p = 0.01 and p = 0.06, respectively) while pre-awake SBP (p = 0.09) along with daytime SBP and DBP load (p = 0.07 and p = 0.06, respectively) were also almost decreased. Conclusions SBG block might be a promising, non-invasive, safe, painless and easy to perform therapeutic option of BP decrease. As with renal denervation, SBG should be effective in those hypertensive patients with an activated SNS, so a period of patient selection should precede the application of this procedure. © 2016 Elsevier Ireland Lt
BILATERAL SPHENOPALATINE GANGLION BLOCK REDUCES BLOOD PRESSURE IN NEVER TREATED PATIENTS WITH ESSENTIAL HYPERTENSION. A RANDOMIZED CONTROLLED SINGLE-BLINDED STUDY
No full textBackground Sympathetic fibers connect sphenopalatine ganglion (SPG) with the central nervous system. We aimed to study the effect of SPG block in blood pressure (BP) in never treated patients with stage I-II essential hypertension. Methods We performed bilateral SPG block with lidocaine 2% in 33 hypertensive patients (mean age 48 ± 12 years, 24 men) and a sham operation with water for injection in 11 patients who served as the control group (mean age 51 ± 12 years, 8 men). All patients have been subjected to 24 h ambulatory blood pressure monitoring prior and a month after the SBG block in order to estimate any differences in blood pressure parameters. We defined as responders to SBG block those patients with a 24 h SBP decrease ≥ 5 mm Hg. Results We found that 24 h and daytime DBP (p = 0.02) as well as daytime DBP load (p = 0.03) were decreased in the study group a month after SPG block. In addition, a significant response was noted in 12/33 responders (36%) regarding: a. SBP and DBP during overall 24 h and daytime (p < 0.001) and night-time periods, b. pre-awake and early morning SBP and c. SBP (daytime and night-time) and DBP (daytime) load. No differences regarding BP were found in the sham operation group. Conclusions SPG block is a promising, minimally invasive option of BP decrease in hypertensives, probably through SNS modulation. Additionally, due to its anesthetic effect, SPG block might act as a method of selection for those hypertensive patients with an activated SNS before any other invasive antihypertensive procedure. © 2017 Elsevier B.V
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