Recent
            31
            P n.m.r. studies of myocardium

Earlier work from this laboratory has concerned the possible use of phosphorus n.m.r. as a method to monitor, in a non-invasive manner, the biochemical state of the perfused heart as a function of its mechanical performance. We showed that a simulated coronary infarction could be detected by 31 P n.m.r. (Hollis et al 1978 a and that hypothermia and KC1 arrest could preserve the pH and the ATP levels at more nearly normal values than in a non-arrested heart during long periods (40 min) of ischaemia (Hollis et al . 1978 b ).More recently it was shown that multiple doses of KC1, given at intervals, were more effective in this respect than was a single dose (Flaherty et al . 1979). These studies essentially followed the kinetics of transitions of the heart between two or more distinct physiological states (i.e. normoxic and ischaemic, with or without KC1 arrest) by observation of the 31 P n.m.r. spectra at various time intervals over periods of up to 1 h. As described in detail and demonstrated in Dr Truman Brown’s contribution to these discussions, the rates of chemical exchange reactions occurring in a steady state can be measured by the techniques of saturation transfer in various biological systems, including perfused hearts.

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Heparin Excretion in Intact and Hepatectomized Rats

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650152 ◽

1981 ◽

Vol 45 (02) ◽

pp. 146-149

Author(s):

Ray Losito ◽

Harry Gattiker ◽

Ginette Bilodeau

Keyword(s):

Column Chromatography ◽

Normal Values ◽

Anticoagulant Activity ◽

Biliary Fistula ◽

Kinetics Of ◽

Intact Rats

SummaryMetabolism and kinetics of 3H-heparin were compared in intact and hepatectomized rats. Rats were divided into three groups: 1) intact rats with biliary fistulas and cystostomies 2) intact rats with only cystostomies and 3) hepatectomized rats with cystostomies. Radioactivity in blood, bile and urine besides anticoagulant activity in blood and urine were examined. In addition, column chromatography of urine was used to isolate possible metabolites. Seventy percent and 80% of the radioactive dose was found in the urine of intact rats at 24 hr and 48 hr. Close to 5% of the radioactivity was found in bile or rats with a biliary fistula after 48 hr. The APTT declined to near normal values at 1 hr whether rats had a biliary fistula or not. In contrast, only 25 % of the radioactivity could be excreted into the urine of hepatectomized rats in 24 hr; the APTT did not decline as fast and at 5 hr, it was still 100 seconds. Only one radioactive component could be isolated on chromatography from all urines of these animals and appears to be similar to the original heparin. Thus, the liver has an important role to play in regulating the anticoagulant effects and excretion of heparin.

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Use of Treated Non-Ferrous Metallurgical Slags as Supplementary Cementitious Materials in Cementitious Mixtures

Applied Sciences ◽

10.3390/app11094028 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4028

Author(s):

Asghar Gholizadeh Vayghan ◽

Liesbeth Horckmans ◽

Ruben Snellings ◽

Arne Peys ◽

Priscilla Teck ◽

...

Keyword(s):

Mechanical Performance ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Partial Replacement ◽

Strength Development ◽

Supplementary Cementitious Material ◽

Performance Requirements ◽

Metallurgical Slags ◽

Leaching Behaviour ◽

Kinetics Of

This research investigated the possibility of using metallurgical slags from the copper and lead industries as partial replacement for cement. The studied slags were fayalitic, having a mainly ferro-silicate composition with minor contents of Al2O3 and CaO. The slags were treated at 1200–1300 °C (to reduce the heavy metal content) and then granulated in water to promote the formation of reactive phases. A full hydration study was carried out to assess the kinetics of reactions, the phases formed during hydration, the reactivity of the slags and their strength activity as supplementary cementitious material (SCM). The batch-leaching behaviour of cementitious mixtures incorporating treated slags was also investigated. The results showed that all three slags have satisfactory leaching behaviour and similar performance in terms of reactivity and contribution to the strength development. All slags were found to have mediocre reactivity and contribution to strength, especially at early ages. Nonetheless, they passed the minimum mechanical performance requirements and were found to qualify for use in cement.

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A network of Rab GTPases controls phagosome maturation and is modulated by Salmonella enterica serovar Typhimurium

The Journal of Cell Biology ◽

10.1083/jcb.200611056 ◽

2007 ◽

Vol 176 (3) ◽

pp. 263-268 ◽

Cited By ~ 107

Author(s):

Adam C. Smith ◽

Won Do Heo ◽

Virginie Braun ◽

Xiuju Jiang ◽

Chloe Macrae ◽

...

Keyword(s):

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Dominant Negative ◽

Rab Gtpases ◽

Wild Type ◽

Intracellular Growth ◽

Non Invasive ◽

Serovar Typhimurium ◽

Guanosine Triphosphatase ◽

Kinetics Of

Members of the Rab guanosine triphosphatase (GTPase) family are key regulators of membrane traffic. Here we examined the association of 48 Rabs with model phagosomes containing a non-invasive mutant of Salmonella enterica serovar Typhimurium (S. Typhimurium). This mutant traffics to lysosomes and allowed us to determine which Rabs localize to a maturing phagosome. In total, 18 Rabs associated with maturing phagosomes, each with its own kinetics of association. Dominant-negative mutants of Rab23 and 35 inhibited phagosome–lysosome fusion. A large number of Rab GTPases localized to wild-type Salmonella-containing vacuoles (SCVs), which do not fuse with lysosomes. However, some Rabs (8B, 13, 23, 32, and 35) were excluded from wild-type SCVs whereas others (5A, 5B, 5C, 7A, 11A, and 11B) were enriched on this compartment. Our studies demonstrate that a complex network of Rab GTPases controls endocytic progression to lysosomes and that this is modulated by S. Typhimurium to allow its intracellular growth.

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Kinetics of some uranyl nitrate-organic phosphate exchange reactions

Journal of Inorganic and Nuclear Chemistry ◽

10.1016/0022-1902(71)80441-4 ◽

1971 ◽

Vol 33 (5) ◽

pp. 1451-1456 ◽

Cited By ~ 11

Author(s):

Yair Egozy ◽

Shmuel Weiss

Keyword(s):

Uranyl Nitrate ◽

Organic Phosphate ◽

Exchange Reactions ◽

Phosphate Exchange ◽

Kinetics Of

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The kinetics of solid-state isotope-exchange reactions for clumped isotopes: A study of inorganic calcites and apatites from natural and experimental samples

American Journal of Science ◽

10.2475/05.2015.01 ◽

2015 ◽

Vol 315 (5) ◽

pp. 363-411 ◽

Cited By ~ 77

Author(s):

D. A. Stolper ◽

J. M. Eiler

Keyword(s):

Solid State ◽

Isotope Exchange ◽

Clumped Isotopes ◽

Exchange Reactions ◽

Kinetics Of

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Kinetics of bioactive compounds in functional spice Jiangpo during thermal processing

International Journal of Food Engineering ◽

10.1515/1556-3758.2768 ◽

2012 ◽

Vol 8 (3) ◽

Author(s):

Xiaoyan Dai ◽

Chenhuan Yu ◽

Qiaofeng Wu

Keyword(s):

Kinetic Parameters ◽

Bioactive Compounds ◽

Thermal Processing ◽

Order Rate Constant ◽

Heat Processing ◽

Order Kinetic ◽

Time Intervals ◽

First Order ◽

Order Kinetic Model ◽

Kinetics Of

Abstract Jiangpo is an increasingly popular East Asian spice which is made from Mangnolia officinalis bark and ginger juice. Since it induces bioactive compounds decomposition and has influence on final flavor and fragrance, cooking is regarded as the key operation in preparation of Jiangpo. To evaluate the bioactive compounds content changes of Jiangpo during thermal processing, kinetic parameters including reaction order, rate constant, T1/2 and activation energy of bioactive markers namely honokiol, magnolol and curcumin were determined. Cooking was set at temperatures 60, 90 and 120 °C for selected time intervals. Results displayed the thermal kinetic characteristics of the three compounds. Thermal degradation of Honokiol and magnolol both followed first order kinetic model and the loss of curcumin fitted second order. A mathematical model based on the obtained kinetic parameters has also been developed to predict the degradation of honokiol, magnolol and curcumin in non-isothermal state. All the information in this paper could contribute necessary information for optimizing the existing heat processing of Jiangpo.

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The kinetics of isotope exchange reactions: Use of initial rates to measure isotope effects on carbon acid ionization

International Journal of Chemical Kinetics ◽

10.1002/kin.550140104 ◽

1982 ◽

Vol 14 (1) ◽

pp. 19-34 ◽

Cited By ~ 3

Author(s):

A. J. Kresge ◽

M. F. Powell

Keyword(s):

Isotope Exchange ◽

Isotope Effects ◽

Exchange Reactions ◽

Carbon Acid ◽

Kinetics Of ◽

Acid Ionization

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Abstract 202: Aging Alters the Electrical and Mechanical properties of LV Myocytes

Circulation Research ◽

10.1161/res.113.suppl_1.a202 ◽

2013 ◽

Vol 113 (suppl_1) ◽

Author(s):

Andrea Sorrentino ◽

Sergio Signore ◽

Mark Sundman ◽

Ramaswamy Kannappan ◽

Chiara Mangiaracina ◽

...

Keyword(s):

Mechanical Performance ◽

Na Channel ◽

Relaxation Phase ◽

Qt Intervals ◽

K Current ◽

Electrocardiographic Parameters ◽

Perfused Hearts ◽

Old Mice ◽

Ionic Basis

Aging results in delays in the electrical recovery of the heart, enhancing the risk of malignant ventricular arrhythmias and sudden death. But whether altered electrical properties affect myocardial mechanical performance remains unclear. The aim of this study was to establish the ionic basis for the protracted repolarization of the senescent heart, and to determine whether these electrical changes impact on myocardial contractility. For this purpose, electrophysiological analyses were conducted in vivo and in isolated LV myocyte preparations from mice ranging from 3 to 30 months of age. Electrocardiographic parameters were preserved from 3 to 12 months of age, whereas animals 2 years or older presented prolonged PR, QRS and QT intervals. These in vivo results were confirmed in the isolated organ, using Langendorff perfused hearts. Myocytes from 30 months old mice showed longer early and late repolarization phases of the action potential (AP), in comparison with cells from animals at 3 months. By voltage-clamp, the density of the transient outward K+ current (Ito) was significantly reduced in old, whereas the late Na+ current (INaL) was increased, changes consistent with the prolonged AP of old cells. Additionally, by Western blotting, the SCN1B subunit, involved in Na+ channel gating, was reduced with age. Using field stimulation, old myocytes presented slower Ca2+ transient decay and relaxation, in comparison to young. Blockade of INaL with mexiletine in old myocytes shortened the AP duration, and fastened the decay of Ca2+ transients and relaxation. To assess the functional impact of INaL on the myocardium, papillary muscles were studied in an isometric system. Using tension-length protocols, old muscles presented elevated diastolic tension with respect to young. Importantly, inhibition of INaL in old muscles reduced diastolic tension, and attenuated the active developed force. Conversely, increasing INaL in the myocardium of young mice with anemonetoxin had opposite effects. Overall, these data indicate that aging results in a prolongation of the AP mediated, at least in part, by enhanced INaL. The prolonged repolarization of the AP contributes to the slower clearance of diastolic Ca2+ from the cytoplasm, resulting in protracted relaxation phase.

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Chemical Interaction-Induced Evolution of Phase Compatibilization in Blends of Poly(hydroxy ether of bisphenol-A)/Poly(1,4-butylene terephthalate)

Materials ◽

10.3390/ma11091667 ◽

2018 ◽

Vol 11 (9) ◽

pp. 1667

Author(s):

Jing Liu ◽

Hsiang-Ching Wang ◽

Chean-Cheng Su ◽

Cheng-Fu Yang

Keyword(s):

Bisphenol A ◽

Chemical Interaction ◽

Chemical Exchange ◽

Hydroxyl Group ◽

Random Copolymers ◽

Exchange Reactions ◽

Butylene Terephthalate ◽

Alcoholysis Reaction ◽

Immiscible Blend ◽

Hydroxy Ether

An immiscible blend of poly(hydroxy ether of bisphenol-A) (phenoxy) and poly(1,4-butylene terephthalate) (PBT) with phase separation was observed in as-blended samples. The compatibilization of phenoxy/PBT blends can be promoted through chemical exchange reactions of phenoxy with PBT upon annealing. The annealed phenoxy/PBT blends had a homogeneous phase with a single Tg that could be enhanced by annealing at 260 °C. Infrared (IR) spectroscopy demonstrated that phase homogenization could be promoted by annealing the phenoxy/PBT blend, where alcoholytic exchange occurred between the dangling hydroxyl group (–OH) in phenoxy and the carbonyl group (C=O) in PBT in the heated blends. The alcoholysis reaction changed the aromatic linkages to aliphatic linkages in the carbonyl groups, which initially led to the formation of a graft copolymer of phenoxy and PBT with an aliphatic/aliphatic carbonyl link. The progressive alcoholysis reaction resulted in the transformation of the initial homopolymers into block copolymers and finally into random copolymers, which promoted phase compatibilization in blends of phenoxy with PBT. As the amount of copolymers increased upon annealing, the crystallization of PBT was inhibited by alcoholytic exchange in the blends.

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