[Differences in spatial structures of the influenza virus M1 protein in crystal, solution and virion].

Spatial structure of the influenza virus A/Puerto Rico/8/34 (PR8, subtype H1N1) M1 protein in a solution and composition of the virion was studied by tritium planigraphy technique. The special algorithm for modeling of the spatial structure is used to simulate the experiment, as well as a set of algorithms predicting secondary structure and disordered regions in proteins. Tertiary structures were refined using the program Rosetta. To compare the structures in solution and in virion, also used the X-ray diffraction data for NM-domain. The main difference between protein structure in solution and crystal is observed in the contact region of N- and M-domains, which are more densely packed in the crystalline state. Locations include the maximum label is almost identical to the unstructured regions of proteins predicted by bioinformatics analysis. These areas are concentrated in the C-domain and in the loop regions between the M-, N-, and C-domains. Analytical centrifugation and dynamic laser light scattering confirm data of tritium planigraphy. Anomalous hydrodynamic size, and low structuring of the M1 protein in solution were found. The multifunctionality of protein in the cell appears to be associated with its plastic tertiary structure, which provides at the expense of unstructured regions of contact with various molecules-partners.

[Modeling of protein spatial structure using tritium planigraphy].

The results of proteins spatial structure modeling using the tritium planigraphy technique are presented. The knowledge of three-dimensional structure of macromolecules is extremely necessary to understand the basic mechanisms of interaction in biological systems and complex technological processes. Known limitations of the X-ray analysis (crystal state) and NMR (molecular weight) make it necessary to seek new approaches to modeling the spatial structure of proteins. Semiempirical tritium planigraphy technique is one of these approaches. The method is based on the bombardment of the object by beam of hot tritium atoms (E(at) > or = 0.3 eV) and a computer simulation experiment. On the example of proteins of the different structural classes we set that by using this integrated approach can be obtained by three-dimensional model of the structure, well consistent with the data of X-ray analysis. An important factor is a sequence search of contacts between secondary structure elements: the best fit model with the native structure is achieved by assembling the elements of a vector in the sequence from the N- to C-terminus of the polypeptide chain.

[Acute colonic pseudoobstruction: Ogilvie's syndrome].

Based on literature and own original clinical data authors conclude that Ogilvie's syndrome is the form of dynamic obstruction of colon due to lesion of retroperitoneal neural nodes, heart failure and intoxication. Ogilvie's syndrome complicates therapeutic and surgical diseases. This syndrome can be manifested with acute abdomen symptoms and at 22% cases may be the cause of surgical treatment. Ogilvie's syndrome is successfully treated with evacuation of intestinal contents, but the risk of recurrence after this treatment is high. Ethiotropic therapy, correction of water-electrolytic balance and tissues oxygenation, administration of acetylcholinesterase inhibitors are the more effective treatment of this syndrome.

[Foreign bodies of the rectum].

The experience in the treatment of 143 patients with foreign bodies of the rectum and sigmoid colon is analyzed. Groups of foreign bodies are distinguished according to their size, structure and ways of occurring. Methods of extraction of foreign bodies in typical and non-typical situations are described. It is demonstrated that in 2.8% cases of extraction surgeries laparotomy is required even without perforation of this organ.

[Treatment of epithelial coccygeal fistula].

Analysis of treatment of 822 patients with epithelial coccygeal fistula has demonstrated that purulent complication is indication for primary radical surgery. Number of complications and recurrences decreases if the first focus of inflammation is treated and epithelial fistula is resected after healing of the wound. Anaerobic inflammation is seen in 0.4% patients with purulent epithelial coccygeal fistula. These patients require radical resection of affected tissues and general intensive therapy. There were no lethal outcomes after treatment of inflammatory complications. Hospital stay was 7.7 bed-days. All the surgical methods have disadvantages. Proposed method demonstrates the best results. Suppuration of the wounds was seen in 0.7% cases, recurrences -- in 1.1% patients.

[Anaerobic paraproctitis]. / Anaérobnyi paraproktit.

Anaerobic paraproctitis (AP) was seen in 8.6% of 1057 cases with acute paraproctitis. Severe general condition of the patient, vast damage, fetid wound secretion, extensive detachment and necrosis of tissues were the main AP symptoms. Radical excision of affected tissues with daily revision and sanatation in combination with intensive general therapy permits to reduce mortality to 4.3%. In early postoperative period reversible insufficiency of anal sphincter developed in 16.1% AP patients. It is necessary to close wounds as early as possible. Perforated cutaneous pedicle flap from posterior wall of the scrotum may be successfully used for plastic repair of perineum wound.

Studying the spatial organization of membrane proteins by means of tritium stratigraphy: bacteriorhodopsin in purple membrane.

The topography of bacteriorhodopsin (bR) in situ was earlier studied by using the tritium bombardment approach [Eur. J. Biochem. 178 (1988) 123]. Now, having the X-ray crystallography data of bR at atom resolution [Proc. Natl. Acad. Sci. 95 (1998) 11673], we estimated the influence of membrane environment (lipid and protein) on tritium incorporation into amino acid residues forming transmembrane helices. We have determined the tritium flux attenuation coefficients for residues 10-29 of helix A. They turned out to be low (0.04+/-0.02 A(-1)) for residues adjacent to the lipid matrix, and almost fourfold higher (0.15+/-0.05 A(-1)) for those oriented to the neighboring transmembrane helices. We believe that tritium incorporation data could help modeling transmembrane segment arrangement in the membrane.

Studying liposomes by tritium bombardment.

Bilayer liposomes from a mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine (DPPC: DPPE = 8:2, molar ratio) or DPPC labeled with 14C-DPPC (DPPC: 14C-DPPC) were bombarded with thermally activated tritium atoms. The tritiated liposomes were hydrolyzed by phospholipase C, and the tritium incorporation into different parts of the bilayer along its thickness was determined. The tritium flux attenuation coefficients were calculated for the headgroup (k1 = 0.176+/-0.032 A(-1)) and acylglycerol residue (k2 = 0.046+/-0.004 A(-1)) layers indicating a preferential attenuation of the tritium flux in the headgroup region and relative transparence of the membrane hydrophobic part. The finding is potentially important to apply tritium bombardment for investigation of spatial organization of transmembrane proteins in their native lipid environment.

[The monitoring of gas bubbles with a pulsed Doppler ultrasonic locator in humans working in a space suit]. / Monitoring gazovykh puzyr'kov ul'trazvukovym impul'sno-dopplerovskim lokatorom u cheloveka pri rabote v skafandre.

Presented are results of gas bubbles monitoring in decompressed humans with the use of an ultrasonic pulse-Doppler locator (PDL). Unlike the classic Doppler bubbles detectors with continuous US emission, PDL is adjusted for reception of echo from a chosen volume of the right ventricle cavity; thus, the clutter due to cardiac beats and human locomotion is successfully rejected. During simulation of Russian EVAs, venous gas bubbles were detected in 3 out of 5 experiments with test-subjects clothed in everyday wear and in 2 out of 3 experiments with suited test-subjects.

The in situ spatial arrangement of the influenza A virus matrix protein M1 assessed by tritium bombardment.

Intact influenza A virions were bombarded with thermally activated tritium atoms, and the intramolecular distribution of the label in the matrix protein M1 was analyzed to determine the in situ accessibility of its tryptic fragments. These data were combined with the previously reported x-ray crystal structure of the M1 fragment 2-158 [Sha, B. & Luo, M. (1997) Nat. Struct. Biol. 4, 239-244] and the predicted topology of the C domain (159-252) to propose a model of M1 arrangement in the virus particle.

Tritium planigraphy: from the accessible surface to the spatial structure of a protein.

The method of tritium planigraphy, which provides comprehensive information on the accessible surface of macromolecules, allows an attempt at reconstructing the three-dimensional structure of a protein from the experimental data on residue accessibility for labeling. The semiempirical algorithm proposed for globular proteins involves (i) predicting theoretically the secondary structure elements (SSEs), (ii) experimentally determining the residue-accessibility profile by bombarding the whole protein with a beam of hot tritium atoms, (iii) generating the residue-accessibility profiles for isolated SSEs by computer simulation, (iv) locating the contacts between SSEs by collating the experimental and simulated accessibility profiles, and (v) assembling the SSEs into a compact model via these contact regions in accordance with certain rules. For sperm whale myoglobin, carp and pike parvalbumins, the lambda cro repressor, and hen egg lysozyme, this algorithm yields the most realistic models when SSEs are assembled sequentially from the amino to the carboxyl end of the protein chain.

[The structural characteristics of the polyribosomes in the rat liver studied by means of a tritium label]. / Osobennosti struktury poliribosom pecheni krys, izuchennye metodom tritievoi metki.

Polyribosomes isolated from the rat liver in a medium with low ionic strength were irradiated by "hot" tritium atoms under conditions providing for the replacement of the hydrogen atoms located at the surface of polyribosomes by tritium. After fractionation of such polyribosomes, the radioactivity of the obtained fractions was measured and their proportions were calculated for the total surface accessible for the tritium atoms (in %), as well as their specific radioactivity. The material loosely associated with the polyribosomes and containing amino acyl-tRNA-synthetases is more radioactive than rRNA and r-proteins, especially concerning their specific radioactivity. This suggests that the material is organized as individual molecules located on the surface of ribosomes. The specific radioactivity of the RNA-component of this material (tRNA) is twice that of proteins, thus suggesting its surface localization in the composition of loosely associated material. Based on the pattern of labeling of rRNA and r-proteins of the native and preliminarily dissociated polyribosomes, we propose that the material, loosely associated with the polyribosomes, has affinity to both rRNA and r-proteins.

[The concept of the "accessible surface" of the protein within the framework of tritium planigraphy. Experiment and calculation]. / Poniatie "dostupnaia poverkhnost" belka v ramkakh metoda tritevoi planigrafii. Eksperiment i raschet.

Tritium planigraphy allows one to determine the sterical accessibility of protein hydrocarbon fragments (CH, CH2, CH3 groups) for interaction with tritium atoms on condition of direct transit of the bombarding particles. Using lysozyme as a test system, it was shown to be possible to use these data for the description of protein accessible surface area in terms defined by Lee and Richards. The best agreement between experimental and theoretical results was achieved for an effective radius of the testing probe of 0.9 A. Coefficients were obtained that allowed calculation of the accessibility of amino acid residue as a whole using data about its hydrocarbon fragment accessibility.