The binding of CO2 to human hemoglobin.

CO2-dissociation curves of concentrated human deoxy- and carbonmonoxyhemoglobin at 37 degrees, pH 7.6 to 7.0, PCO2 equal to 10 to 160 mm Hg, have been obtained by a rapid mixing and ion exchange technique. The CO2-dissociation curves for deoxyhemogloblin can only be fitted by assuming two classes of binding sites for carbon dioxide. The simplest way to account for the experimental data is to assume that the alpha-amino groups of the alpha and beta chains react with carbon dioxide with affinities that differ by at least a factor of 3. No difference in reactivity with CO2 was found among the four terminal alpha-amino groups of carbonmonoxyhemoglobin

Recent advances in the chemistry of metal carbamates

Following a related review dating back to 2003, the present review discusses in detail the various synthetic, structural and reactivity aspects of metal species containing one or more carbamato ligands, representing a large family of compounds across all the periodic table. A preliminary overview is provided on the reactivity of carbon dioxide with amines, and emphasis is given to recent findings concerning applications in various fields

(Poly)phenolic content and profile and antioxidant capacity of whole-grain cookies are better estimated by simulated digestion than chemical extraction

It is widely recognized that the biological effects of phytochemicals cannot be attributed to the native compounds present in foods but rather to their metabolites endogenously released after intake. Bioavailability depends on bioaccessibility, which is the amount of the food constituent that is released from the matrix in the gastrointestinal tract. The use of chemical extraction to evaluate the content and profile of phytochemicals does not mirror the physiological situation in vivo, and their bioaccessibility should be considered while assessing their nutritional significance in human health. The current study was designed to compare the (poly)phenolic profile and content and antioxidant capacity of whole-grain (WG) cookies using chemical extraction and a more physiological approach based on simulated digestion. Three types of organic WG cookies (made with durum, Italian khorasan, or KAMUT\uae khorasan wheat) were considered, either fermented by Saccharomyces Cerevisiae or sourdough. Although the flour type and the fermentation process influenced the release of phytochemicals from the cookie matrix, in almost all samples, the simulated digestion appeared the most efficient procedure. Our results indicate that the use of chemical extraction for evaluation of the phytochemicals content and antioxidant capacity of food could lead to underestimation and underline the need for more physiological extraction methods

Asymmetric saccade reaction times to smooth pursuit

Before initiating a saccade to a moving target, the brain must take into account the target’s eccentricity as well as its movement direction and speed. We tested how the kinematic characteristics of the target influence the time course of this oculomotor response. Participants performed a step-ramp task in which the target object stepped from a central to an eccentric position and moved at constant velocity either to the fixation position (foveopetal) or further to the periphery (foveofugal). The step size and target speed were varied. Of particular interest were trials that exhibited an initial saccade prior to a smooth pursuit eye movement. Measured saccade reaction times were longer in the foveopetal than in the foveofugal condition. In the foveopetal (but not the foveofugal) condition, the occurrence of an initial saccade, its reaction time as well as the strength of the pre-saccadic pursuit response depended on both the target’s speed and the step size. A common explanation for these results may be found in the neural mechanisms that select between oculomotor response alternatives, i.e., a saccadic or smooth response

Diiron bis-cyclopentadienyl complexes as transfer hydrogenation catalysts: The key role of the bridging aminocarbyne ligand

The catalytic activity of a series of diiron complexes based on the {Fe2Cp2(CO)(x)} core (x = 2-3) and containing a bridging aminocarbyne ligand was screened in transfer hydrogenation reaction of cyclohexanone from isopropanol. The series includes cationic tricarbonyl complexes, [1a-d]CF3SO3, and neutral derivatives obtained by substitution of one carbonyl with hydride (2a-c), cyanide (3a-d) or chloride (4a) ligands. The novel compounds 2a-b, 3a-b and 4a were characterized by analytical and spectroscopic techniques, and the single crystal X-ray structure of one isomer of 4a was determined. In general, diiron complexes exhibited a moderate activity in combination with potassium hydroxide; [Fe2Cp2(CN)(CO)(mu-CO){mu-CN (Me)(4-C6H4OMe)}], 3a, emerged as the best catalyst, and the study of its activity was extended to a range of other ketones. DFT calculations suggest an unusual carbyne-centred mechanism, and the better performance displayed by 3a is ascribable to the stabilizing effect provided by the cyanide co-ligand, which is experimentally supported by IR analyses

Matching optical flow to motor speed in virtual reality while running on a treadmill

We investigated how visual and kinaesthetic/efferent information is integrated for speed perception in running. Twelve moderately trained to trained subjects ran on a treadmill at three different speeds (8, 10, 12 km/h) in front of a moving virtual scene. They were asked to match the visual speed of the scene to their running speed–i.e., treadmill’s speed. For each trial, participants indicated whether the scene was moving slower or faster than they were running. Visual speed was adjusted according to their response using a staircase until the Point of Subjective Equality (PSE) was reached, i.e., until visual and running speed were perceived as equivalent. For all three running speeds, participants systematically underestimated the visual speed relative to their actual running speed. Indeed, the speed of the visual scene had to exceed the actual running speed in order to be perceived as equivalent to the treadmill speed. The underestimation of visual speed was speed-dependent, and percentage of underestimation relative to running speed ranged from 15% at 8km/h to 31% at 12km/h. We suggest that this fact should be taken into consideration to improve the design of attractive treadmill-mediated virtual environments enhancing engagement into physical activity for healthier lifestyles and disease prevention and care

Potent Antioxidant and Anti-Tyrosinase Activity of Butein and Homobutein Probed by Molecular Kinetic and Mechanistic Studies †

Butein (BU) and homobutein (HB) are bioactive polyhydroxylated chalcones widespread in dietary plants, whose antioxidant properties require mechanistic definition. They were investigated by inhibited autoxidation kinetic studies of methyl linoleate in TritonTM X-100 micelles at pH 7.4, 37 °C. Butein had kinh = (3.0 ± 0.9) × 104 M−1s−1 showing a chain-breaking mechanism with higher antioxidant activity than reference α-tocopherol (kinh = (2.2 ± 0.6) × 104 M−1s−1), particularly concerning the stoichiometry or peroxyl radical trapping n = 3.7 ± 1.1 vs. 2.0 for tocopherol. Homobutein had kinh = (2.8 ± 0.9) × 103 M−1s−1, pairing the relative BDEOH measured by radical equilibration EPR as 78.4 ± 0.2 kcal/mol for BU and estimated as 82.6 kcal/mol for HB. The inhibition of mushroom tyrosinase (mTYR) by HB and BU was also investigated. BU gives a reversible uncompetitive inhibition of monophenolase reaction with KI′ = 9.95 ± 2.69 μM and mixed-type diphenolase inhibition with KI = 3.30 ± 0.75 μM and KI′ = 18.75 ± 5.15 μM, while HB was nearly competitive toward both mono- and diphenolase with respective KI of 2.76 ± 0.70 μM and 2.50 ± 1.56 μM. IC50 values (monophenolase/diphenolase at 1 mM substrate) were 10.88 ± 2.19 μM/15.20 ± 1.25 μM, 14.78 ± 1.05 μM/12.36 ± 2.00 μM, and 33.14 ± 5.03 μM/18.27 ± 3.42 μM, respectively, for BU, HB, and reference kojic acid. Molecular docking studies confirmed the mechanism. Results indicate very potent antioxidant activity for BU and potent anti-tyrosinase activity for both chalcones, which is discussed in relation to bioactivity toward protection from skin disorders and food oxidative spoilage

Surgical treatment of primary tracheal tumors in children and adolescents

Pediatric primary tracheal tumors (PTTs) are rare entities, with an estimated incidence of 0.2% among all neoplasms in children and adolescents. Benign lesions and malignancies are rather equally represented, with subglottic hemangioma, granular cell tumor, carcinoid tumor, and low-grade mucoepidermoid carcinoma being the most common histotypes. Guidelines on management and treatment of pediatric PTTs are not available, and only a few reviews, case reports, and single surgeon/institute experiences have been published. A literature search was carried out focusing on the surgical approaches utilized in the most recent publications to manage pediatric PTTs, thus including case reports, single institute experiences, and reviews on surgical techniques. Moreover, we divided the available intervention modalities based on an anatomical classification, distinguishing between laryngotracheal, cervical tracheal, lower tracheal, and carinal scenarios. Endoscopic treatment is still underused, even for benign lesions: this is mainly due to the difficulties that surgeons may experience during airway management, appropriate tumor visualization, and its safe removal with adequate prevention/management of intraoperative complications. Considering open surgery, simple tumorectomy via median thyrotomy is the treatment of choice whenever possible (mainly for benign tumors), whereas in case of wider excisions, laryngotracheal resection and reconstruction with cartilage graft, end-to-end anastomosis, or neo-carinal reconstruction represent the most widely used procedures. All these techniques are similar to what described in adults. Strict cooperation with an experienced team of pediatric anesthesiologists and intensivists is of paramount importance for the adequate management of PTTs in young children. We are far from establishing a common guideline for treatment of PTTs. Mini-invasive procedures should be encouraged and developed since the majority of pediatric histotypes are benign or low-grade cancers. Moreover, patients should be addressed to specialized pediatric centers in order to improve and refine the existing techniques, laying the groundwork for the proposal of new procedures.