The paper reports a study aimed at investigating tertiary education students’ engagement and interactions in the traditional face-to-face learning environment and the sequentially applied distance online learning environment imposed by the sudden upsurge of a worldwide health emergency, the COVID-19 pandemic in Spring 2020. The study took place in four distinct science learning communities formed by a total of 347 undergraduate students attending three different academic majors (Chemistry, Environmental Science, and Food Science and Technology) and 13 postgraduate students attending a Masters program related to Chemistry Education, in two Greek universities. The majority of the measured variables were shown to depend on the institution, the academic major, and the semester of study, although to a varying degree. Data analysis provided evidence for a statistically significant lower level of emotional engagement in the online relative to the traditional learning environment among the students of all three undergraduate learning communities. Multiple regression analysis showed that this documented decrease in students’ emotional engagement is largely explained by the concurrent decrease at the level of human interaction (either student–student or student–instructor) upon the passage from the traditional to the online learning environment.

The development of renin inhibitors for the treatment of hypertension requires highly sensitive substrates to evaluate potency and to characterize the mechanism of tight-binding inhibitors. A series of intramolecularly quenched fluorogenic renin substrates, based on the N-terminal tetradecapeptide sequence of human angiotensinogen (hTDP), was synthesized using a solid-phase technique. Incorporation of the fluorescent amino acid L-Amp [L-2-amino-3-(7-methoxy-4-coumaryl)propionic acid] and the DNP (2,4-dinitrophenyl) group at various positions resulted in >90% quenching efficiency and strong product fluorescence. Shortening the hTDP sequence to an octapeptide from histidine in P5 to histidine in P3' (substrate 3) resulted in an acceptable k(cat)/K(m) (41000 M(-1).s(-1)) and further systematic variation gave substrate 9, DNP-Lys-His-Pro-Phe-His-Leu-Val-Ile-His-L-Amp, with a k(cat)/K(m) value of 350000 M(-1).s(-1) and 94% quenching efficiency. The free side chain of lysine, replacing the isoleucine residue at P6 position in the angiotensinogen sequence, contributed to the increased value for k(cat). The pH dependence of k(cat)/K(m) for renin and substrate 9 showed that the optimal pH is at pH 6-7. It also showed two titrating groups on the acidic side of the pH optimum, and one titrating group with a pK(a) of 7.8 on the alkaline side. The combination of good kinetic and spectroscopic properties resulted in a >20-fold improvement in the sensitivity of renin assay, compared with the commercial substrate Arg-Glu(EDANS)-Ile-His-Pro-Phe-His-Leu-Val-Ile-His-Thr-Lys(DABCYL)-Arg [where EDANS is 5-[(2-aminoethyl)amino]naphthalene-1-sulphonic acid and DABCYL is 4-(4-dimethylaminophenylazo)benzoic acid] (k(cat)/K(m)=268000 M(-1) x s(-1), quenching efficiency <80%). The detection limit in a microplate renin assay was 60 pM, making substrate 9 well suited for the evaluation of inhibitors at picomolar concentrations.

No abstract

Ischemic stroke (IS) exhibits significant heterogeneity in terms of etiology and pathophysiology. Several recent studies highlight the significance of inflammation in the onset and progression of IS. White blood cell subtypes, such as neutrophils and monocytes, participate in the inflammatory response in various ways. On the other hand, high-density lipoproteins (HDL) exhibit substantial anti-inflammatory and antioxidant actions. Consequently, novel inflammatory blood biomarkers have emerged, such as neutrophil to HDL ratio (NHR) and monocyte to HDL ratio (MHR). Literature research of two databases (MEDLINE and Scopus) was conducted to identify all relevant studies published between 1 January 2012 and 30 November 2022 dealing with NHR and MHR as biomarkers for IS prognosis. Only full-text articles published in the English language were included. Thirteen articles have been traced and are included in the present review. Our findings highlight the utility of NHR and MHR as novel stroke prognostic biomarkers, the widespread application, and the calculation of which, along with their inexpensive cost, make their clinical application extremely promising.

Katherine Paschalidou and Chryssa Tzougraki: A general and direct method for the solid phase synthesis of intramolecular quenched fluorogenic protease substrates using a bifunctional coumarin derivative, Letters in Peptide Science 7 (2000), 249-253. Please note the following changes.