Induction of mouse liver glyoxalase I by hypobaric hypoxia

Hypobaric hypoxia at 0.45 atm induced a reversible increase of mouse liver glyoxalase I. The levels of this enzyme increased after an exposure of 20 h and 20 + 20 h, whereas the activity decreased to the control values after 20 h at room pressure. Before the treatment, some animals received tritiated leucine (i.p.). Glyoxalase I was purified to homogeneity. The pure enzyme from the treated animals showed 20-times more radioactivity than the controls. Thus, the increase in specific activity is due to new protein synthesized in response to the treatment at 0.45 atm. The activities of glyoxalase II and glutathione S-transferase were not affected by the treatment.     

Circadian Rhythm and Seasonal Variations in Basal cAMP Content of Rat Heart Ventricles

The cAMP content in rat heart ventricles was studied at 3-hr intervals during 24hr at different times of the year. A significant circadian rhythm in cAMP content was found. Time of the year reproducibly influenced the 24-hr mean, the amplitude as well as the peak value in cAMP in relation to circadian time.     

Changes of plasma insulin, urea, amino acids and rumen metabolites in somatotropin treated dairy cows

Summary An experiment was performed to evaluate the effects of somatotropin on plasma free amino acid, urea and insulin concentrations and rumen fermentation pattern and to assess their relationships. Four Italian Friesian dairy cows fitted with rumen cannulae were used in a switch-back design. Slow releasing recombinant bovine somatotropin (640 mg/cow) was injected every 28 days for two consecutive periods. Rumen fluid and blood samples were collected before and after feeding at 0, 7 and 21 days after rbST injection. Exogenous rbST increased plasma insulin concentration and the insulin response to feeding, and decreased plasma urea and free essential and branched chain amino acid concentrations. rbST did not affect rumen fermentation pattern. No correlation was found between rumen and plasma parameters measured after feeding. Our results are consistent with the notion that the main effect of somatotropin is post-absorptive.     

Catalytic activity of dihydride ruthenium complexes in the hydrogenation of nitrogen containing heterocycles

The catalytic activity of the dihydride ruthenium complexes, RuH₂(CO)₂(PⁿBu₃)₂, RuH₂(CO)₂(PPh₃)₂ and RuH₂(PPh₃)₄, in the hydrogenation of nitrogen containing heterocycles has been tested by analyzing the influence of reaction parameters such as temperature, hydrogen pressure, catalyst concentration, on the rate and regioselectivity of the reaction.RuH₂(PPh₃)₄ shows a better catalytic activity with an 86.7% conversion of quinoline after 24 h at 100 °C under a hydrogen pressure of 25 bar, while RuH₂(CO)₂(PPh₃)₂ and RuH₂(CO)₂(PⁿBu₃)₂ in the same conditions give a conversion of 37.1% and 35.6%, respectively. These results are confirmed by the reaction rate of the hydrogenation of quinoline, since the K_c in the presence of RuH₂(PPh₃)₄ (1.46 × 10⁻⁵ s⁻¹) is higher than others (6.37 × 10⁻⁶ s⁻¹ for RuH₂(CO)₂(PPh₃)₂ and 6.36 × 10⁻⁶ s⁻¹ for RuH₂(CO)₂(PⁿBu₃)₂).Noteworthy is the selectivity of these catalytic systems in the hydrogenation of quinoline: in all tests the three catalysts lead to 1,2,3,4-tetrahydroquinoline as the major product, furthermore this compound is the only formed in the presence of RuH₂(CO)₂(PPh₃)₂. The selectivity is affected by the presence of an acid (CH₃COOH) or a base (NⁿBu₃) in the reaction media.The complex RuH₂(PPh₃)₄ is catalytically active, even if in a minor extent, in the hydrogenation of isoquinoline, pyridine and 2-methylpyridine.The basicity of the substrate and steric hindrance around the nitrogen atom show a great influence on the conversion.The results obtained suggest that the catalytic system activates a heterocyclic ring through the coordination of the heteroatom to the metal centre of the complexes.     

Assessing the effective elastic properties of the tendon-to-bone insertion: a multiscale modeling approach

Biomechanics and Modeling in Mechanobiology - The interphase joining tendon to bone plays the crucial role of integrating soft to hard tissues, by effectively transferring stresses across two...     

Conceptualizing world art studies: An introduction

This special issue aims to contribute to the conceptualization of World Art Studies. The first two articles offer evaluative views from art history, the third and fourth perspectives from anthropology, the fifth and sixth arguments for including neo-evolutionary and neurological studies in understanding world art as a universal human behavior.