Novel peptide inhibitors of myosin light chain kinase suppress the hyperpermeability of vascular endothelium

The ability of novel cell-permeating peptide molecules derived from the peptide inhibitor of myosin light chain kinase (MLCK), L-PIK (Arg-Lys-Lys-Tyr-Lys-Tyr-Arg-Arg-Lys) to inhibit this kinase in vitro and attenuate the thrombin-induced hyperpermeability of endothelial cell monolayer in culture has been studied. It was found that compounds [N^αMeArg¹]-L-PIK and [Cit¹]-L-PIK possess inhibitory activity towards MLCK comparable to that of L-PIK and the ability to suppress the hyperpermeability of endothelium, whereas other modifications of L-PIK were less effective. Thus, among de novo synthesized peptides, [N^αMeArg¹]-L-PIK and [Cit¹]-L-PIK demonstrate the inhibitory properties of the original peptide L-PIK and additionally surpass it in stability in blood plasma. These peptides may be used in the design of novel antiedemic drugs.     

Study of the effects of amyotrophic leukospongiosis causative agent on neuroglia cells in vitro

The influence of amyotrophic leukospongiosis (AL) causative agent on the ultrastructure of different types of cells of dissociated rat embryo brain and spinal cord cultures was studied. The AL agent belongs to the unconventional viruses (prions) and causes degenerative changes in the CNS. Large neurons and fibrous astrocytes were shown to be most sensitive. It was noted that the time of development and the degree of the dystrophic changes depend on the agent concentration. The destruction of cell membranes resulted in the pair neuron confluence. The formation of giant mitochondria with intramitochondrial inclusions was detected. It is supposed that the energetic apparatus of sensitive cells is primarily damaged by the infectious agent.     

Rho-associated protein kinase is involved in establishing the cardiomyocyte contractile phenotype

We have shown that Y-27632, an inhibitor of Rho-associated kinase (ROCK), delays sarcomere assembly in cultured rat neonatal cardiomyocytes pretreated with angiotensin II. Y-27632 affects the beat rate of cardiomyocytes, but this effect is only observed at high cell density and, therefore, seems to be related to impairment of cell-cell interactions. Consistent with this suggestion, ROCK2 is localized in myofibrillar Z-disks of human myocardium as well as in intercalated disks. We propose that ROCK participates in maturation of the myocardial contractile system through phosphorylation of its molecular targets in Z-disks and in intercalated disks.     

Trial of different nutrient media for the production of an intracellular thermolabile enterotoxin by Escherichia coli strains H74-114 and 86

The conditions of cultivation, ensuring the maximum accumulation of intracellular thermolabile enterotoxin in the cultures of two E. coli strains of different origin, have been studied. Culture media manufactured in the USSR have been selected and the conditions of cultivation, necessary for obtaining intracellular thermolabile enterotoxin in preparative amounts, have been established. Under these conditions the yield of thermolabile enterotoxin in 1.4 mg per 1 liter of culture medium for strain H74-114 and 1.0 mg per 1 liter of culture medium for strain 86.     

Ability of Citrobacter freundii strains isolated in acute intestinal infections to produce LT-enterotoxin

C. freundii enteropathogenic strains were found to be capable of producing choleroform thermolabile enterotoxin. Thus, in the study of 96 C. freundii strains 38 enterotoxin-producing cultures (39.5%) were revealed by means of the molecular-biological techniques and 29 such cultures (30.0%), by means of the radioimmunoassay (RIA). 100% coincidence was noted in the results of tests for enterotoxigenicity, made by means of RIA or hybridization techniques with the use of the LT-probe containing a cloned fragment with the gene coding the synthesis of LT-enterotoxin in enterotoxigenic Escherichia coli. At the same time only 29 out of 38 Citrobacter strains found to be positive in the hybridization tests, yielded the positive result when tested in RIA for the presence of LT-enterotoxin. This fact should be taken into consideration in the determination of enterotoxin-producing cultures isolated in acute enteric infections, as the method of genetic probing is capable of bringing out the genetic information in bacteria even in the absence of its phenotypical expression.     

Preparation and Properties of Complexes Based on Chitosan-Ag Nanocomposite and Cephalosporin Antibiotics

Applied Biochemistry and Microbiology - Aggregatively stable, positively charged (~45 mV) chitosan-Ag nanocomposites with a spherical shape and size up to 60.0 nm were synthesized by the...