Search Results - (Author, Cooperation:J. L. Boyer)

2015-02-28

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2,4-Dinitrophenol/*administration & dosage/toxicity ; Animals ; Blood Glucose/metabolism ; Delayed-Action Preparations/*administration & dosage ; Diabetes Mellitus, Type 2/*drug therapy/metabolism ; Glucose Tolerance Test ; Insulin Resistance ; Lipid Metabolism ; Liver Cirrhosis/drug therapy ; Male ; Mice ; Mitochondria, Liver/drug effects/metabolism ; Muscle, Skeletal/metabolism ; Non-alcoholic Fatty Liver Disease/*drug therapy/metabolism ; Oxidation-Reduction ; Proton Ionophores/*administration & dosage/toxicity ; Random Allocation ; Rats ; Rats, Zucker

1600-0838

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Sports Science

Various studies report a 0–22% per decade decline in circulatory function (VO2max) with advancing age. Twelve exercising men (E) were followed for 28 years, mean age 43 and 71 years, initial to final measurement, while 12 dropouts (C) detrained for 21 years, with a mean age from first to last measurement of 48 and 69 years, respectively. VO2 max in E changed from 45.9 to 39.4 ml · min−1· kg−1, 5% per decade, whereas C declined from 36.0 to 21.4 ml min−1· kg−1, 19% per decade. Resting blood pressure was unchanged in E, 119/75 mmHg, whereas C rose from 128/85 to 149/90 mmHg. The data suggest that regular aerobic exercise forestalls the usual loss of circulatory function with increasing age.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1432-1424

hepatocyte ; ion conductances ; membrane potential ; (Na+/K+)-ATPase ; intracellular ion activities ; sinusoidal membrane ; canalicular membranes ; paracellular transport

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Summary The basic electrical properties of an isolated rat hepatocyte couplet (IRHC) system have been analyzed using classical techniques of epithelial electrophysiology, including measurement of electric potentials, resistances and intracellular ion activities. Applications of these techniques are discussed with respect to their limitations in small isolated cells. Mean intracellular and intracanalicular membrane potentials ranged from −23.7 to −46.7 and −4.3 to −5.9 mV, respectively. Membrane resistances were determined using an equivalent circuit analysis modified according to the geometry of the IRHC system. Resistances of the sinusoidal (basolateral) and canalicular (luminal) cell membranes and tight junctions averaged 0.15 and 0.78 GΩ and 25mΩ, respectively. The cells are electrically coupled via low resistance intercellular communications (∼58 MΩ). Intracellular ion activities for Na+, K+ and Cl− averaged 12.2, 88.1 and 17.7 mmol/liter, respectively. The basolateral membrane potential reveals a permeability sequence ofP K〉P Cl〉P Na. The luminal potential showed minimal dependence on changes in transjunctional ion gradients, indicating a poor ion selectivity of the paracellular pathway. The electrogenic (Na+−K)-ATPase contributes little to the luminal and cellular negative electric potential. Therefore, the luminal potential probably results from the secretion of impermeant ions and a Donnan distribution of permeant ions, a mechanism which provides the osmotic driving force for bile formation. By providing the unique opportunity to measure luminal potentials, this isolated hepatocyte system permits study of secretory mechanisms for the first time in a mammalian gland using electrophysiologic techniques.

Electronic Resource

1432-0614

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Summary An analysis of the effect of water during the enzymatic esterification reaction between a fatty acid and a fatty alcohol is presented in this article. Adding water at the beginning of the reaction enabled the initial rate to be greatly increased. The action of water was not instantaneous, even though enzyme hydration was rapid. The apparent order of the reaction was zero. If water generated during the reaction was not eliminated, there was a drastic reaction rate decrease, which we attribute to a phenomenon of phase separation. Depending on the experimental conditions, which result in the presence of greater or smaller quantities of water in the medium, a conversion of 0.3, 0.5 or 0.9 is reached within 1 h.

Electronic Resource

1573-0778

Springer Online Journal Archives 1860-2000

Biology

Medicine

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

1432-136X

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary Bile pigment composition (biliverdin, bilirubin and their conjugates) was analyzed in stored gallbladder bile and newly synthesized hepatic bile from the small skate (Raja erinacea). During a five day period of captivity, gallbladder volume remained relatively constant while bilirubin and biliverdin content increased two to three fold. Biliverdin which accounted for 50% of the pigments did not increase as a percentage of tetrapyrroles during this period. The relative proportion of bilirubin and its conjugates also remained constant, averaging 65% for bilirubin monoglucuronide, 30% for bilirubin diglucuronide and 5% for unconjugated bilirubin as measured by HPLC methods. Intravenous administration of biliverdin resulted in significant increases in the biliary excretion of both biliverdin and all bilirubin tetrapyrroles. Insignificant quantities of3H-biliverdin were detected in hepatic bile following the intravenous administration of3H-bilirubin. These studies indicate that the small skate excreted both biliverdin and bilirubin conjugates in bile and that the biliverdin was not produced by in vitro oxidation of bilirubin or its metabolites.

Electronic Resource

0749-1581

13C NMR ; Sultones ; Sulphonate-sulphate anhydrides ; Chemistry ; Analytical Chemistry and Spectroscopy

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

The 13C NMR spectra of 20 compounds belonging to several types of monocyclic sultones and related ‘carbyl sulphates,’ including a series of fluorinated β-sultones (1,2-oxathietane 2,2-dioxides), are reported. Chemical shift increment systems with n-alkanes as reference molecules are established for non-fluorinated sultones: they show a much less pronounced deshielding effect on the carbon α to oxygen in β-sultones than in the other series. Chemical shifts for the parent β-sultone, predicted in two ways (linear or cyclic model compound), are found to be almost consistent with a purely additive scheme. In fluorinated β-sultones the α-substituent increments relative to perfluoroethanesultone are also derived.

8 Tab.

Electronic Resource

0749-1581

NMR ; 13C NMR ; chemical shift ; sulphonated compounds ; fluorosulphonic acids ; Chemistry ; Analytical Chemistry and Spectroscopy

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

A chemical shift analysis of the 13C NMR spectra of more than 50 acyclic sulphonic acids, alkali metal sulphonates and methyl esters was carried out. Chemical shift increment systems with n-alkanes as reference molecules were established for linear alkanesulphonates and alk-2-enesulphonates. Some short-chain fluorinated sulphonic acids were also studied, especially pentafluorothio derivatives. C—F spin-spin coupling constants were determined. Pauling electronegativity values for SO3H and SF5 groups were derived from α chemical shift increments.

5 Tab.

Electronic Resource