Changes of cerebral glutamine,glutamic acid and GABA during arousal from hibernation

Résumé Chez le spermophile, la teneur en glutamine et en acide glutamique cérébral au cours du réveil du sommeil hivernal était inchangée. Pendant le réchauffement des animaux refroidis, la glutamine et GABA étaient remarquablement élevés.     

Oxytocin analogs effective as noncompetitive inhibitors in uterotonic test

Summary Deamino-1-carba-oxytocin analogs with a chemically reactive group in position 4 were demonstrated to act as noncompetitive oxytocin inhibitors in the assay on isolated rat uterus.     

The lack of insulin-binding to simple glycosidic receptors

Summary The results of affinity electrophoresis at pH 8.9 show that insulin does not interact with any of a number of glycosidic ligands which bind various lectins. The results are discussed with respect to some similarities between insulin and concanavalin A.     

Cataract induced by administration of a single dose of sodium selenite to suckling rats

Summary A single dose of sodium selenite to male suckling rats causes permanent or intermittent cataracts. The resistance to the lethal effect of selenite in suckling rats is significantly higher in comparison with adult animals.     

Immunoadjuvant activity of synthetic N-acetyl muramyl dipeptide

Summary The administration of phosphatidyl choline/cholesterol liposomes with entrapped N-acetyl muramyl dipeptide induced in guinea-pigs the development of delayed hypersensitivity to ovalbumin.     

Formation of cardiovascular tubes in invertebrates and vertebrates

The cardiovascular system developed early in evolution and is pivotal for the transport of oxygen, nutrients, and waste products within the organism. It is composed of hollow tubular structures and has a high level of complexity in vertebrates. This complexity is, at least in part, due to the endothelial cell lining of vertebrate blood vessels. However, vascular lumen formation by endothelial cells is still controversially discussed. For example, it has been suggested that the lumen mainly forms via coalescence of large intracellular vacuoles generated by pinocytosis. Alternatively, it was proposed that the vascular lumen initiates extracellularly between adjacent apical endothelial cell surfaces. Here we discuss invertebrate and vertebrate cardiovascular lumen formation and highlight the possible modes of blood vessel formation. Finally, we point to the importance of a better understanding of vascular lumen formation for treating human pathologies, including cancer and coronary heart disease.     

Diffusion of d-glucose measured in the cytosol of a single astrocyte

Astrocytes interact with neurons and endothelial cells and may mediate exchange of metabolites between capillaries and nerve terminals. In the present study, we investigated intracellular glucose diffusion in purified astrocytes after local glucose uptake. We used a fluorescence resonance energy transfer (FRET)-based nano sensor to monitor the time dependence of the intracellular glucose concentration at specific positions within the cell. We observed a delay in onset and kinetics in regions away from the glucose uptake compared with the region where we locally super-fused astrocytes with the d-glucose-rich solution. We propose a mathematical model of glucose diffusion in astrocytes. The analysis showed that after gradual uptake of glucose, the locally increased intracellular glucose concentration is rapidly spread throughout the cytosol with an apparent diffusion coefficient (D _app) of (2.38 ± 0.41) × 10^?10 m² s^?1 (at 22–24 °C). Considering that the diffusion coefficient of d-glucose in water is D = 6.7 × 10^?10 m² s^?1 (at 24 °C), D _app determined in astrocytes indicates that the cytosolic tortuosity, which hinders glucose molecules, is approximately three times higher than in aqueous solution. We conclude that the value of D _app for glucose measured in purified rat astrocytes is consistent with the view that cytosolic diffusion may allow glucose and glucose metabolites to traverse from the endothelial cells at the blood–brain barrier to neurons and neighboring astrocytes.     

Reinigung mikrobiologischer Objekte zur Vorbereitung elektronenmikroskopischer Präparate durch Ultrafiltration

Summary A method for preparation of electron microscopic specimens by ultrafiltration can be used for bacteriophages, mycoplasma, and fragile biological particles, especially from solutions containing low concentrations of these particles and when it is necessary to remove also macromolecules up to a certain size.     

35S-Sulphate incorporation into myelin sulphated mucopolysaccharides during rat brain development

Summary Rat brain myelin acid mucopolysaccharides (AMPS) incorporate 15%, 8%, 5.5% and 4% of tojtal associated³⁵S-sulphate, 14, 21, 30 and 75 days after birth, respectively. The course of³⁵S-sulphate incorporation into total rat brain mucopolysaccharides, as well in those from myelin, had a similar feature with peak on the 2nd week and a significant decrease on the 3rd and 4th week postnatally.