Changes in erythrocyte velocity in microvessels measured with a microprismatic grating

Using an instrument designed by the Ernst Leitz Wetzlar Company (FRG) red blood cell velocity was evaluated in model and intravital experiments. The instrument provides for an accurate quantitative determination of blood microflow velocity, enables the measurements within a wide range of velocities and diameters of microvessels. It is more unsophisticated as regards the design and operation than other instruments intended for similar purposes.     

Pharmacological characteristics of a new phenyl analog of piracetam--4-phenylpiracetam

The central neurotropic effects of 4-phenylpyracetam, a new phenyl analog of pyracetam, were studied and compared with the effects of pyracetam, morpholene and 4-phenylpyrrolidone. 4-Phenylpyracetam was found to activate the operant behavior more powerfully, to remove psychodepressant effects of diazepam, to inhibit post-rotational nystagmus, and to prevent the development of retrograde amnesia. Unlike pyracetam, 4-phenylpyracetam exhibits a specific anticonvulsant action. When given in high doses, the compound under study produces psychodepressant effects.     

Mechanism of action of an exopolysaccharide from Mycobacterium cyaneum on the local cellular reaction in experimental coli infection

A study was made of the effect of the exopolysaccharide (PS) M. cyaneum B-646 on cellular reaction in peritoneal exudate of white mice infected with E. coli. PS intensified the migration of phagocytic cells to the focus of infection, accelerated neutrophil maturation, promoted an earlier and more active involvement of neutrophils, particularly of macrophages, into the phagocytic process. In this case, there was a marked correlation between the magnitude of phagocyte population (of macrophage population to a greater degree) in peritoneal exudate and absorption capacity. PS activated macrophagal lysosomes, affecting selectively the accumulation of enzymes by the cells and lysosomal membrane permeability. The action of PS is dose-dependent. Under experimental conditions in question, the most favourable effect on local cellular reaction was exerted by PS in a dose of 20 micrograms per mouse.     

Low-temperature glass transition in proteins

The viscoelastic properties of solid samples (crystals, amorphous films) of hen egg white lysozyme, bovine serum albumin, and sperm whale myoglobin were studied in the temperature range of 100–300 K at different hydration levels. Decreasing the temperature was shown to cause a steplike increase in the Young's modulus of highly hydrated protein samples (with water content exceeding 0.3 g/g dry weight of protein) in the temperature range of 237–251 K, followed by a large increase in the modulus in the broad temperature interval of 240–130 K, which we refer to as a mechanical glass transition. Soaking the samples in 50% glycerol solution completely removed the steplike transition without significantly affecting the glass transition. The apparent activation energy determined from the frequency dependence of the glass-transition temperature was found to be 18 kcal/mol for wet lysozyme crystals. Lowering the humidity causes both the change of the Young's modulus in response to the transition and the activation energy to decrease. The thermal expansion coefficient of amorphous protein films also indicates the glass transition at 150–170 K. The data presented suggest that the glass transition in hydrated samples is located in the surface layer of proteins and related to the immobilization of the protein groups and strongly bound water.