Arthropod toxins inhibiting Ca2+ and Na+ channels prevent AC‐1001 H3 peptide‐induced apoptosis

Peptide toxins of arthropods are one of the potential sources of bioactive substances. Toxins are able to bind to calcium channels and block them. Ca²⁺ ions play an important role in many cell processes, in particular, in apoptosis. In this work, we study the effect of some arthropod toxins on intracellular processes associated with the induction of apoptosis. Synthetic analogs of U₅‐scytotoxin‐Sth1a, ω‐hexatoxin‐Hv1a, ω‐theraphotoxin‐Hhn2a, and μ‐agatoxin‐Aa1a toxins—inhibitors of calcium L, P, and Q channels and sodium channels were used in the study. Apoptosis was induced by AC‐1001 H3 peptide. We study the effect of toxins on the level of apoptosis, ROS, mitochondrial potential, GSH, and ATP in CHO‐K1 cells. We show that all the tested toxins are able to dose dependently block the induction of apoptosis triggered by AC‐1001 H3 and reduce the level of natural apoptosis in CHO‐K1 cells. Cell incubation with apoptosis inducer AC‐1001 H3 in the presence and absence of toxins causes an increase in the intracellular concentrations of ROS, ATP, and mitochondrial potential and decreases the GSH concentration. The present study reveals the antiapoptotic effect of a number of arthropod peptide toxins. The toxins studied can represent a novel approach used in the treatment of pathologies associated with the activation of apoptotic mechanisms.     

Etiology of severe hospital infections in intensive care units and antibiotic resistance of pathogens]

The leading pathogens of severe infections in intensive care units were the following: respiratory tract infections--bacteria of the famility of Enterobacteriaceae (33.8%), Pseudomonas spp. (24.9%), Acinetobacter spp. (18.1%), Staphylococcus aureus (16.0%), blood flow infections--coagulase negative staphylococci (33.6%), S. aureus (26.1%), Enterobacteriaceae (17.6%), wound infections--Enterobacteriaceae (35.7%), coagulase negative staphyloccocci (17.8%), Pseudomonas spp. (14.3%). As for various species of Enterobacteriaceae, susceptibility was preserved in 91-100% of the isolates to meropenem, in 72-100% to cefoperazone/sulbactam, in 51-65% to cefepime, in 72-86% to amikacin, and in less than 50% to cephalosporins and fluoroquinolones. As for P.aeruginosa, 28% of the isolates was resistant to all the antibacterials, except polymyxin. The highest susceptibility to cefoperazone/sulbactam and meropenem was revealed in the isolates of Acinetobacter baumannii. Oxacillin resistance was detected in 64.9% of the S.aureus isolates. The oxacillin resistance as a rule was associated with resistance to macrolides, aminoglycosides and fluoroquinolones. As for coagulase negative staphylococci, oxacillin resistance was stated in 75.6% of the isolates. All the isolates of the Staphylococcus spp. preserved their susceptibility to vancomycin and linezolid.     

Microbial origin of phenylcarboxylic acids in the human body

In previous studies we demonstrated increased amounts of phenylcarboxylic acids (PCA) in serum of patients with sepsis. This observation prompted the present study of the ability of the human microbiome bacteria to produce PCA in vitro. PCA were detected in culture media by gas chromatography-mass spectrometry. Increased amounts of phenyllactic and p-hydroxyphenyllactic acids were produced by Klebsiella pneumonia, Escherichia coli, and Staphylococcus aureus. Certain strict anaerobes (bifidobacteria, lactobacteria, eubacteria) have also been found to actively produce these PCA, but these bacteria are not etiologically linked to sepsis. Thus our results demonstrate the ability of sepsis-related bacteria to produce PCA and provide experimental support for the theory that the accumulation of PCA in the blood of patients with sepsis results from microbial degradation of phenylalanine and tyrosine.     

Multicentre study of comparative efficacy of meropenem and combined regimens for empirical antibacterial therapy of severe nosocomial infections: results of clinical and pharmacoeconomic analysis]

Adequacy and effectiveness of empirical antibacterial therapy of severe nosocomial infections with meropenem vs. combined regimens of antibacterial therapy were investigated and the ratio of the cost and effectiveness of the compared regimens was evaluated. A prospective, randomized, open, comparative study of two initiative regimens of empirical antibacterial therapy of severe nosocomial infections was performed: meropenem in a daily dose of 1.5-3 g and the standard regimen with the use of betalactams and fluoroquinolones in combination with aminoglycosides and/or metronidazole. Patients with recorded diagnosis of nosocomial pneumonia (including the ventilator-associated one) or abdominal infection with the signs of severe sepsis and severity of APACHE II > 14 were enrolled. The patients were stratified into 2 groups subject to the disease severity, i.e. APACHE II 15-20 and APACHE II 21-25. One hundred thirty five out of 166 patients with recorded nosocomial infection were included into the final estimate of the therapy adequacy and effectiveness (Protocol Analysis): 62 patients were treated with meropenem and in the treatment of 73 patients the standard antibacterial therapy was used. In the group of the patients treated with meropenem there were stated significantly higher clinical effectiveness (recovery in 80.6% of the patients vs. the control of 46.6%, p < 0.01) and pathogen eradication (89.6 and 48.1% respectively, p < 0.01). The difference in the clinical and bacteriological effectiveness of meropenem and the standard therapy was more evident in the subgroups of more severe patients (APACHE > 20). With the use of meropenem the probability of recovery from nosocomial infection was significantly higher (RR 1.73-1.94, p < 0.001) vs. the control. Meropenem provided significantly higher eradication of the pathogens: P. aeruginosa (88 and 40% respectively, p = 0.007), E. coli (100 and 46.7%, p = 0.003), Acinetobacter spp. (90.9 and 40%, p = 0.02). The antibacterial therapy with the use of meropenem was assessed as adequate in 51 out of 56 patients (91.1%), that was 3 times as frequent as with the use of the standard antibacterial therapy (33.9%). The cost-effectiveness coefficient with the use of meropenem was 2.2 times lower vs. the control. Therefore, the empirical therapy of severe nosocomial infections with meropenem proved to be more adequate and from the economic viewpoint more advantageous vs. the standard combined regimens of antibacterial therapy, that was evident from significantly higher clinical and bacteriological efficacy of the treatment and decrease of the terms of the patients hospitalization in intensive care units (on the average by 5 days).     

Actual aspects of sepsis

Cases of sepsis with bacteriemia detected in the S. P. Botkin State Clinical Hospital within 2000-2007 were analysed. The sources of the bacteriemia, the etiological pattern of the pathogens and their susceptibility to antibacterials were estimated. The study enrolled 256 patients with sepsis. The antibiotic susceptibility of 227 isolates from the blood samples was tested. More than a half of the infection sources was detected in the organs of the respiratory tract and abdominal cavity. All the grampositive pathogens were susceptible to vancomycin and linesolid. The overwhelming majority of the enterococcal isolates proved to be susceptible to carbapenem and cefepim.