[A case of irreversible cardiomyopathy induced by polychemotherapy].

The paper describes a case of irreversible dilated cardiomyopathy in a young female patient receiving polychemotherapy for breast cancer.

["Evidance"--Russian national epidemiological study].

UNLABELLED: The article deals with results of epidemiological study of 2516 ICU patients received prophylaxis of a deep vein thrombosis (DVT) and venous thromboembolic complications (VTEC). RESULTS: The frequency of renal failure was 19.8%. Mortality rate in patients with acute renal failure (ARF) was 34% and in patients without ARF 17%. CONCLUSIONS: An analysis of drugs for prophylaxis of DVT and VTEC which were used in patients with ARF showed that the prophylaxis was performed without a taking in account a significance of such complication.

[Significance of static pressure-volume loop and lung computed tomography for differential diagnostics of parenchymal respiratory insufficiency].

UNLABELLED: Purpose of the study was to determine a significance of static pressure-volume loop and lung computed tomography for differential diagnostics of parenchymal lung failure developing during mechanical ventilation. MATERIALS AND METHODS: 75 patients (42 males and 33 females) with acute lung failure due to parenchymal lung injury during mechanical ventilation were included in to the research. Criteria of including into the research were age over 15, ARDS symptoms absence before respiratory support beginning and modified American-European Consensus Conference ARDS criteria presence during mechanical ventilation (AECC ARDS criteria, 1994--PaO2/FiO2 < 250 mmHg). Lung computed tomography (CT), static compliance and plateau measurement were performed in all patients. Static pressure-volume loop was plotted in 23 patients. RESULTS: diffuse alveolar damage was diagnosed by CT in 24.3% of patients and "wet sponge" symptom in 10.7% of patients. Dorsal atelectasis (77.3%) and ventilator-associated pneumonia (VAP) (82.7%) were diagnosed in most of patients with AECC ARDS criteria. Sensitivity and specificity of PaO2/FiO2 ratio were too low for diagnostics of ARDS (AUROC 0.67) Patients with diffuse alveolar damage had plateau pressure 25 mbar (95% CI 22-32), while patients with local lung injury (VAP or atelectasis) had significantly lower plateau pressure--20 mbar (95% CI 18-22) (p = 0.014). Elevation of plateau pressure over 30 mbar predicted diffuse alveolar damage with specificity of 100%. Lower inflection point values on the static pressure-volume loop was higher in patients with diffuse alveolar damage than in patients with local lung injury--12 mbar (95% CI 7-17) vs. 6 mbar (95% CI 5-10), (p = 0.042, n = 23). Effective (linear) compliance had poor prognostic value for differential diagnostics of acute respiratory failure due to parenchimal lung injury (p = 0.023). CONCLUSION: Lung CT plays leading role in differential diagnostics of parenchymal lung failure developing during mechanical ventilation. In the luck of CT scan elevation of plateau pressure over 30 mbar and values of lower inflection point on the static pressure-volume loop over 12 mbar can predict ARDS.

[Bacteriophage enzymes for the prevention and treatment of bacterial infections: stability and stabilization of the Streptococcus pyogenes cell lysing enzyme].

The effect of various compounds on the activity and stability of a phage-associated enzyme lysing cells of streptococci of groups A and C (PlyC) was investigated. Substantial inhibition of the enzyme activity was revealed at an increased ionic strength (in the presence of NaCl) and upon the addition of carbohydrates (mono-, di-, and polysaccharides), i.e., agents stabilizing many enzymes. It was established that the enzyme activity was substantially reduced in the presence of positively charged polyelectrolytes and surfactants, whereas incubation with micelle-forming substances and negatively charged polyelectrolytes led to PlyC activation and stabilization. It was shown that, in the mycelial polyelectrolyte composition M16, the enzyme retained its activity for 2 months; while in a buffer solution under the same conditions (pH 6.3, room temperature), it practically completely lost its activity in 2 days. Characteristics of the enzyme thermal inactivation were found, in particular, its semiinactivation time at various temperatures; these allowed us to estimate its behavior at any temperature and to recommend conditions for its storage and use.

[Alveolar mobilization maneuver (recruitment): solved and unsolved problems].

Acute respiratory distress syndrome (ARDS) is a common complication in patients with critical condition. Studies of pathophysiological changes in the lung in this condition give rise to new methods of respiratory therapy, one of which is alveolar mobilization maneuver (recruitment). This procedure considerably improves oxygenation in patients with ARDS, but at the same time, there is a risk of developing various complications (barotraumas, lowered cardiac output). Further studies of the efficiency of this method and development of well-defined clinical guidelines that will be able to answer the most important questions: "who", "when", and "how" the alveolar recruiting maneuver should perform are currently under way.

[Prediction of fatal outcome in severe injury].

The paper reflects the results of a study to predict a fatal outcome in severe injury, by evaluating the condition by the APACHE II, SAPS II, MODS, SOFA, and Glasgow coma scale. Particular emphasis is laid on the assessment of the quality of an obtained prediction, by using the currently available tools--the resolving power of a prognostic model (area under the characteristic curve), choice of the prognostive value (division point), and calibration of the model. It was ascertained that the APACHE II and SAPS II scales could not significantly predict a fatal outcome in severe injury. Based on the scores obtained by the SOFA, MODS, and Glasgow coma scales, the authors developed prognostic indices that provide a high significance in predicting the fatal outcome in severe injury both within the first 24 hours and over time. The independent predictor of a fatal outcome (hypernatriemia) in severe injury was identified.

Characterization of antigenic properties of horseradish peroxidase with monoclonal antibodies.

Monoclonal antibodies (mcAbs) specific to alkaline isoenzymes of horseradish peroxidase were used to characterize the antigenic properties of horseradish peroxidase. The results of a competitive binding assay indicated that monoclonal antibodies can be divided into three groups directed against distinct parts of the protein. The interaction of monoclonal antibodies with native and modified horseradish peroxidase showed also three different patterns of reactivity. Antibodies from groups I and II are directed against epitopes which are conformational and formed by tertiary structure elements. Epitopes recognized by these antibodies are sensitive to heme removal or partial denaturation of peroxidase. Antibodies from group III bind specifically with epitopes consisting of primary or secondary structure elements. The antigenic determinants recognized by antibodies from group III PO(1) and 36F(9) were shown to be linear (continuous) and formed by amino acid residues 261-267 and 271-277, respectively, as determined by the peptide scanning method (PEPSCAN). The location of revealed linear antigenic determinants in the molecular structure of peroxidase is analyzed.

Epitope mapping of horseradish peroxidase (isoenzyme C).

Peptide scanning (PEPSCAN) was used to determine linear antigenic determinants of horseradish peroxidase isoenzyme C (HRPC). For this purpose, we synthesized 303 overlapping hexapeptide fragments (with a step of one amino acid residue) of the protein primary structure and studied their interactions with anti-HRPC polyclonal antisera by ELISA. Experiments with various titers of antisera allowed us to determine linear antigenic determinants of HRPC; several such determinants were spatially located in regular elements of the secondary structure (alpha-helices) found both inside and outside the protein globule. A fraction of epitopes were located in loops and folds of the HRPC peptide chain with irregular shapes. These epitopes contained several functionally important residues: Arg 38, which is part of the active site of the enzyme, as well as Phe 142 and Phe 143, which form a channel allowing aromatic substrates to reach the active site. Amino acid residues that form calcium-binding sites or occur in the vicinity of disulfide bonds are not involved in these epitopes.

Conformational differences between native and recombinant horseradish peroxidase revealed by tritium planigraphy.

Significant conformational differences between native and recombinant horseradish peroxidase have been shown by tritium planigraphy, which includes a method of thermal activation of tritium followed by amino acid analysis of the protein preparation. Comparison of radioactivity distribution among the amino acid residues with the theoretical (calculated) accessibility shows that the recombinant enzyme is characterized by high hydrophobicity and compactness of folding. The protective role of oligosaccharides in native enzyme has been confirmed. An unexpected result of the study is a finding on high accessibility of a catalytic histidine residue in solution. An effect of low dose (3 Gy) of irradiation on the accessibility of amino acid residues has been unequivocally demonstrated. The data can be interpreted as swelling of the compact folding and increase in the surface hydrophilicity of the recombinant enzyme. In the case of native enzyme, irradiation does not cause remarkable changes in the accessibility of amino acid residues indicating the possible extensive radical modification of the native enzyme in the life-course of the cell. The catalytic histidine is an exception. It becomes inaccessible after the enzyme irradiation, while its accessibility in the recombinant enzyme increases. An additional observation of a 5-fold decrease in the rate constant towards hydrogen peroxide points to the destructive effect of irradiation on the hydrogen bond network in the distal domain of the native enzyme molecule and partial collapse of the active site pocket.

Catalytic properties of tryptophanless recombinant horseradish peroxidase.

Heme-containing plant peroxidases (EC 1.11.1.7) contain a highly conserved single tryptophan residue. Its replacement with Phe in recombinant horseradish peroxidase (rHRP) increased the stability of the mutant enzyme in acid media. The kinetic properties of native, wild-type, and W117F mutant recombinant horseradish peroxidase in the reactions of ammonium 2, 2;-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), guaiacol, and o-phenylenediamine oxidation are very similar. However, significant changes in the reaction rate constant characteristic for the monomolecular rate-limiting step ascribed either to product dissociation from its complex with the enzyme or electron transfer from the substrate to the active site within the Michaelis complex were observed. The data indirectly indicate the participation of the single Trp residue in oxidation of ABTS and guaiacol and possible differences in kinetic mechanisms for oxidation of ABTS, guaiacol, and o-phenylenediamine.

Tryptophanless recombinant horseradish peroxidase: stability and catalytic properties.

The tryptophanless mutant of horseradish peroxidase, W117F, has been constructed and expressed in Escherichia coli. The mutation affects enzyme folding and stability. The optimum composition of the refolding medium requires the presence of ammonium sulfate. The yield of mutant is ca. 8000 U per liter of the optimized refolding medium with the specific activity of 1100-1500 U/mg (compared to 25, 000 U per liter and 2000 U/mg for the recombinant wild-type enzyme). The mutant is more stable in acid media, in the reaction course and toward irradiation. The effect of hydrogen peroxide pretreatment on radiation-induced inactivation of the wild-type and mutant enzyme indirectly indicates participation of Trp-117 in electron transfer pathways through the enzyme molecule. This is in agreement with the steady-state kinetic data interpreted in terms of Trp-117 participation in electron transfer within the Michaelis complex.