[Evolution of enhanced recovery after surgery: from the beginning of the study of stress to the introduction in emergency surgery]. / Évoliutsiia kontseptsii uskorennogo vosstanovleniia posle operatsii: ot istokov ucheniia o stresse do ispol'zovaniia v neotlozhnoi khirurgii (obzor literatury).

Effectiveness of enhanced recovery program is being earnestly confirmed in various surgical areas. Certain aspects of fast track rehabilitation are analyzed in the article.

Psychological stress, cocaine and natural reward each induce endoplasmic reticulum stress genes in rat brain.

Our prior research has shown that the transcription of endoplasmic reticulum (ER) stress transcription factors activating transcription factor 3 (ATF3) and ATF4 are induced by amphetamine and restraint stress in rat striatum. However, presently the full extent of ER stress responses to psychological stress or cocaine, and which of the three ER stress pathways is activated is unknown. The current study examines transcriptional responses of key ER stress target genes subsequent to psychological stress or cocaine. Rats were subjected to acute or repeated restraint stress or cocaine treatment and mRNA was isolated from dorsal striatum, medial prefrontal cortex and nucleus accumbens brain tissue. ER stress gene mRNA expression was measured using quantitative polymerase chain reaction (PCR) and RNA sequencing. Restraint stress and cocaine-induced transcription of the classic ER stress-induced genes (BIP, CHOP, ATF3 and GADD34) and of two other ER stress components x-box binding protein 1 (XBP1) and ATF6. In addition, rats living in an enriched environment (large group cage with novel toys changed daily) exhibited rapid induction of GADD34 and ATF3 after 30 min of exploring novel toys, suggesting these genes are also involved in normal non-pathological signaling. However, environmental enrichment, a paradigm that produces protective addiction and depression phenotypes in rats, attenuated the rapid induction of ATF3 and GADD34 after restraint stress. These experiments provide a sensitive measure of ER stress and, more importantly, these results offer good evidence of the activation of ER stress mechanisms from psychological stress, cocaine and natural reward. Thus, ER stress genes may be targets for novel therapeutic targets for depression and addiction.

[Phylogenetic analysis of cytomegaloviruses isolated from man and different primate species].

Institute of Medical Primatology, Russian Academy of Medical Sciences, Sochi The conserved regions of nucleotide sequences were found in primate cytomegaloviruses (CMV). Universal primers were designed for the consensus sequence of a conservative region of the UL56 gene of the betaherpesvirinae subfamily. Amplification, sequencing, and phylogenetic analysis of the fragments of CMV strains isolated from man and different primate species were made. Analysis of sequenced gene fragments showed that the UL56 gene area is most suitable for the phylogenetic analysis of primate CMV and could identify several groups of clusters by the degree of relationship among the viruses of this family.

The structure of substrate-free microbial ribonuclease binase and of its complexes with 3'GMP and sulfate ions.

The structures of Bacillus intermedius ribonuclease (binase), an extracellular 109-residue enzyme, and its complexes with 3'GMP and sulfate ions were solved at 1.65 and 2.0 A, respectively. The structures were refined using REFMAC. The crystal of free binase belongs to the space group C2, whereas the crystals of complexes belong to the space group P2(1)2(1)2(1). In both crystal lattices the asymmetric unit contains two molecules which form an identical dimer. The structure of the dimer is such that only one of its subunits can bind the nucleotide in the 3'GMP-binase complex, where the guanyl base is located in the recognition loop of the enzyme. In both binase complex structures the phosphate group of 3'GMP or one of the sulfate ions make an electrostatic interaction with the binase molecule at the catalytic site. A second phosphate-binding site was found in the structures of the complexes at the cleft formed by the loop 34-39, the main chain of Arg82 and the side chain of Trp34. Comparison of the complex and unliganded enzyme crystal structures shows that there are some small but distinct differences in the specificity loop (56-62) and in the loops 34-39 and 99-104 associated with the binding of the nucleotide and sulfate ions.

4-Hydroxy-5,6-dihydropyrones as inhibitors of HIV protease: the effect of heterocyclic substituents at C-6 on antiviral potency and pharmacokinetic parameters.

Due largely to the emergence of multi-drug-resistant HIV strains, the development of new HIV protease inhibitors remains a high priority for the pharmaceutical industry. Toward this end, we previously identified a 4-hydroxy-5,6-dihydropyrone lead compound (CI-1029, 1) which possesses excellent activity against the protease enzyme, good antiviral efficacy in cellular assays, and promising bioavailability in several animal species. The search for a suitable back-up candidate centered on the replacement of the aniline moiety at C-6 with an appropriately substituted heterocyle. In general, this series of heterocyclic inhibitors displayed good activity (in both enzymatic and cellular tests) and low cellular toxicity; furthermore, several analogues exhibited improved pharmacokinetic parameters in animal models. The compound with the best combination of high potency, low toxicity, and favorable bioavailabilty was (S)-3-(2-tert-butyl-4-hydroxymethyl-5-methyl-phenylsulfanyl)-4-hydroxy-6-isopropyl-6-(2-thiophen-3-yl-ethyl)-5,6-dihydro-pyran-2-one (13-(S)). This thiophene derivative also exhibited excellent antiviral efficacy against mutant HIV protease and resistant HIV strains. For these reasons, compound 13-(S) was chosen for further preclinical evaluation.

Dielectrical model of cellular structures in radio frequency and microwave spectrum. Electrically interacting versus noninteracting cells.

A model of dielectrical properties of cellular structures of a tissue has been proposed. Cellular structures were presented as a composition of membrane covered spheres and cylinders that do not interact with each other. No restrictions were applied to the thickness of cellular membranes. The model was further generalized into a case of electrically interacting cells. The difference in dielectrical properties calculated with the model of electrically noninteracting versus interacting cells is inversely dependent on frequency. At biological values of cellular volume fraction near 0.7 (packed configuration) the difference is about 10%-15% in resistance and in epsilon' for frequencies near 0.1 MHz. Experimental data for myocardial tissue and theoretical data, for both interacting and noninteracting models, reasonably agree at frequencies of 1-100 MHz.

Structure-activity relationships and pharmacokinetic analysis for a series of potent, systemically available biphenylsulfonamide matrix metalloproteinase inhibitors.

A series of biphenylsulfonamide derivatives of (S)-2-(biphenyl-4-sulfonylamino)-3-methylbutyric acid (5) were prepared and evaluated for their ability to inhibit matrix metalloproteinases (MMPs). For this series of compounds, our objective was to systematically replace substituents appended to the biphenyl and alpha-position of 5 with structurally diverse functionalities to assess the effects these changes have on biological and pharmacokinetic activity. The ensuing structure-activity relationship (SAR) studies showed that biphenylsulfonamides substituted with bromine in the 4'-position (11c) significantly improved in vitro activity and exhibited superior pharmacokinetics (C(max), t(1/2), AUCs), relative to compound 5. Varying the lipophilicity of the alpha-position by replacing the isopropyl group of 11c with a variety of substituents, in general, maintained potency versus MMP-2, -3, and -13 but decreased the oral systemic availability. Subsequent evaluation of its enantiomer, 11c', showed that both compounds were equally effective MMP inhibitors. In contrast, the corresponding hydroxamic acid enantiomeric pair, 16a (S-isomer) and 16a' (R-isomer), stereoselectivity inhibited MMPs. For the first time in this series, 16a' provided nanomolar potency against MMP-1, -7, and -9 (IC(50)'s = 110, 140, and 18 nM, respectively), whereas 16a was less potent against these MMPs (IC(50)'s = 24, 78, and 84 microM, respectively). However, unlike 11c, compound 16a' afforded very low plasma concentrations following a single 5 mg/kg oral dose in rat. Subsequent X-ray crystal structures of the catalytic domain of stromelysin (MMP-3CD) complexed with inhibitors from closely related series established the differences in the binding mode of carboxylic acid-based inhibitors (11c,c') relative to the corresponding hydroxamic acids (16a,a').

Microwave spectroscopy of myocardial ischemia and infarction. 2. Biophysical reconstruction.

The proposed dielectrical relaxation model of the myocardium in the microwave spectrum has been verified both on test solutions and on normal canine myocardium. Furthermore, the model was utilized to reconstruct the changes in tissue properties (including myocardial bulk resistance and water content) following myocardial acute ischemia and chronic infarction. It was shown that the reconstructed myocardial resistance and water content correlate dynamically with the process of the development of acute myocardial ischemic injury. In chronic cases the reconstructed resistance and water content of infarcted myocardium are significantly different from that of normal myocardium: the resistance is lower and water content is higher than in normal myocardium.

A rationalization of the acidic pH dependence for stromelysin-1 (Matrix metalloproteinase-3) catalysis and inhibition.

The pH dependence of matrix metalloproteinase (MMP) catalysis is described by a broad bell-shaped curve, indicating the involvement of two unspecified ionizable groups in proteolysis. Stromelysin-1 has a third pK(a) near 6, resulting in a uniquely sharp acidic catalytic optimum, which has recently been attributed to His(224). This suggests the presence of a critical, but unidentified, S1' substructure. Integrating biochemical characterizations of inhibitor-enzyme interactions with active site topography from corresponding crystal structures, we isolated contributions to the pH dependence of catalysis and inhibition of active site residues Glu(202) and His(224). The acidic pK(a) 5.6 is attributed to the Glu(202).zinc.H(2)O complex, consistent with a role for the invariant active site Glu as a general base in MMP catalysis. The His(224)-dependent substructure is identified as a tripeptide (Pro(221)-Leu(222)-Tyr(223)) that forms the substrate cleft lower wall. Substrate binding induces a beta-conformation in this sequence, which extends and anchors the larger beta-sheet of the enzyme. substrate complex and appears to be essential for productive substrate binding. Because the PXY tripeptide is strictly conserved among MMPs, this "beta-anchor" may represent a common motif required for macromolecular substrate hydrolysis. The striking acidic profile of stromelysin-1 defined by the combined ionization of Glu(202) and His(224) allows the design of highly selective inhibitors.

Analysis of the binding of hydroxamic acid and carboxylic acid inhibitors to the stromelysin-1 (matrix metalloproteinase-3) catalytic domain by isothermal titration calorimetry.

Matrix metalloproteinases (MMPs) are implicated in diseases such as arthritis and cancer. Among these enzymes, stromelysin-1 can also activate the proenzymes of other MMPs, making it an attractive target for pharmaceutical design. Isothermal titration calorimetry (ITC) was used to analyze the binding of three inhibitors to the stromelysin catalytic domain (SCD). One inhibitor (Galardin) uses a hydroxamic acid group (pK(a) congruent with 8.7) to bind the active site zinc; the others (PD180557 and PD166793) use a carboxylic acid group (pK(a) congruent with 4.7). Binding affinity increased dramatically as the pH was decreased over the range 5.5-7.5. Experiments carried out at pH 6.7 in several different buffers revealed that approximately one and two protons are transferred to the enzyme-inhibitor complexes for the hydroxamic and carboxylic acid inhibitors, respectively. This suggests that both classes of inhibitors bind in the protonated state, and that one amino acid residue of the enzyme also becomes protonated upon binding. Similar experiments carried out with the H224N mutant gave strong evidence that this residue is histidine 224. DeltaG, DeltaH, DeltaS, and DeltaC(p) were determined for the three inhibitors at pH 6.7, and DeltaC(p) was used to obtain estimates of the solvational, translational, and conformational components of the entropy term. The results suggest that: (1) a polar group at the P1 position can contribute a large favorable enthalpy, (2) a hydrophobic group at P2' can contribute a favorable entropy of desolvation, and (3) P1' substituents of certain sizes may trigger an entropically unfavorable conformational change in the enzyme upon binding. These findings illustrate the value of complete thermodynamic profiles generated by ITC in discovering binding interactions that might go undetected when relying on binding affinities alone.

Effect of species differences on stromelysin-1 (MMP-3) inhibitor potency. An explanation of inhibitor selectivity using homology modeling and chimeric proteins.

For an animal model to predict a compound's potential for treating human disease, inhibitor interactions with the cognate enzymes of separate species must be comparable. Rabbit and human isoforms of stromelysin-1 are highly homologous, yet there are clear and significant compound-specific differences in inhibitor potencies between these two enzymes. Using crystal structures of discordant inhibitors complexed with the human enzyme, we generated a rabbit enzyme homology model that was used to identify two unmatched residues near the active site that could explain the observed disparities. To test these observations, we designed and synthesized three chimeric mutants of the human enzyme containing the single (H224N and L226F) and double (H224N/L226F) mutations. A comparison of inhibitor potencies among the mutant and wild-type enzymes shows that the mutation of a single amino acid in the human enzyme, histidine 224 to asparagine, is sufficient to change the selectivity profile of the mutant to that of the rabbit isoform. These studies emphasize the importance of considering species differences, which can result from even minor protein sequence variations, for the critical enzymes in an animal disease model. Homology modeling provides a tool to identify key differences in isoforms that can significantly affect native enzyme activity.

Three-dimensional microwave tomography: experimental prototype of the system and vector born reconstruction method.

A method of image reconstruction in three-dimensional (3-D) microwave tomography in a weak dielectric contrast case has been developed. By utilizing only one component of the vector electromagnetic field this method allows successful reconstruction of images of 3-D mathematical phantoms. A prototype of the 3-D microwave tomographic system capable of imaging 3-D objects has been constructed. The system operates at a frequency of 2.36 GHz and utilizes a code-division technique. With dimensions of the cylindrical working chamber z = 40 cm and d = 60 cm, the system allows measurement of an attenuation up to 120 dB having signal-to-noise ratio about 30 dB. The direct problem solutions for different mathematical approaches were compared with an experimentally measured field distribution inside the working chamber. The tomographic system and the reconstruction method were tested in simple experimental imaging.

X-ray structure of human stromelysin catalytic domain complexed with nonpeptide inhibitors: implications for inhibitor selectivity.

Effective inhibitors of matrix metalloproteinases (MMPs), a family of connective tissue-degrading enzymes, could be useful for the treatment of diseases such as cancer, multiple sclerosis, and arthritis. Many of the known MMP inhibitors are derived from peptide substrates, with high potency in vitro but little selectivity among MMPs and poor bioavailability. We have discovered nonpeptidic MMP inhibitors with improved properties, and report here the crystal structures of human stromelysin-1 catalytic domain (SCD) complexed with four of these inhibitors. The structures were determined and refined at resolutions ranging from 1.64 to 2.0 A. Each inhibitor binds in the active site of SCD such that a bulky diphenyl piperidine moiety penetrates a deep, predominantly hydrophobic S'1 pocket. The active site structure of the SCD is similar in all four inhibitor complexes, but differs substantially from the peptide hydroxamate complex, which has a smaller side chain bound in the S'1 pocket. The largest differences occur in the loop forming the "top" of this pocket. The occupation of these nonpeptidic inhibitors in the S'1 pocket provides a structural basis to explain their selectivity among MMPs. An analysis of the unique binding mode predicts structural modifications to design improved MMP inhibitors.

Nonpeptidic HIV protease inhibitors possessing excellent antiviral activities and therapeutic indices. PD 178390: a lead HIV protease inhibitor.

With the insight generated by the availability of X-ray crystal structures of various 5,6-dihydropyran-2-ones bound to HIV PR, inhibitors possessing various alkyl groups at the 6-position of 5,6-dihydropyran-2-one ring were synthesized. The inhibitors possessing a 6-alkyl group exhibited superior antiviral activities when compared to 6-phenyl analogues. Antiviral efficacies were further improved upon introduction of a polar group (hydroxyl or amino) on the 4-position of the phenethyl moiety as well as the polar group (hydroxymethyl) on the 3-(tert-butyl-5-methyl-phenylthio) moiety. The polar substitution is also advantageous for decreasing toxicity, providing inhibitors with higher therapeutic indices. The best inhibitor among this series, (S)-6-[2-(4-aminophenyl)-ethyl]-(3-(2-tert-butyl-5-methyl-phenylsulfa nyl)-4-hydroxy-6-isopropyl-5,6-dihydro-pyran-2-one (34S), exhibited an EC50 of 200 nM with a therapeutic index of > 1000. More importantly, these non-peptidic inhibitors, 16S and 34S, appear to offer little cross-resistance to the currently marketed peptidomimetic PR inhibitors. The selected inhibitors tested in vitro against mutant HIV PR showed a very small increase in binding affinities relative to wild-type HIV PR. Cmax and absolute bioavailability of 34S were higher and half-life and time above EC95 were longer compared to 16S. Thus 34S, also known as PD 178390, which displays good antiviral efficacy, promising pharmacokinetic characteristics and favorable activity against mutant enzymes and CYP3A4, has been chosen for further preclinical evaluation.

4-hydroxy-5,6-dihydropyrones. 2. Potent non-peptide inhibitors of HIV protease.

The 4-hydroxy-5,6-dihydropyrone template was utilized as a flexible scaffolding from which to build potent active site inhibitors of HIV protease. Dihydropyrone 1c (5,6-dihydro-4-hydroxy-6-phenyl-3-[(2-phenylethyl)thio]-2H-pyran-2-one) was modeled in the active site of HIV protease utilizing a similar binding mode found for the previously reported 4-hydroxybenzopyran-2-ones. Our model led us to pursue the synthesis of 6,6-disubstituted dihydropyrones with the aim of filling S1 and S2 and thereby increasing the potency of the parent dihydropyrone 1c which did not fill S2. Toward this end we attached various hydrophobic and hydrophilic side chains at the 6-position of the dihydropyrone to mimic the natural and unnatural amino acids known to be effective substrates at P2 and P2'. Parent dihydropyrone 1c (IC50 = 2100 nM) was elaborated into compounds with greater than a 100-fold increase in potency [18c, IC50 = 5 nM, 5-(3,6-dihydro-4-hydroxy-6-oxo-2-phenyl-5-[2-phenylethyl)thio] -2H-pyran-2-yl)pentanoic acid and 12c, IC50 = 51 nM, 5,6-dihydro-4-hydroxy-6-phenyl-6-(2-phenylethyl)-3- [(2-phenyl-ethyl)thio]-2H-pyran-2-one]. Optimization of the 3-position fragment to fill S1' and S2' afforded potent HIV protease inhibitor 49 [IC50 = 10 nM, 3-[(2-tert-butyl-5-methylphenyl)sulfanyl]-5,6-dihydro-4 -hydroxy-6-phenyl-6-(2-phenylethyl)-2H-pyran-2-one]. The resulting low molecular weight compounds (< 475) have one or no chiral centers and are readily synthesized.

Discovery and optimization of nonpeptide HIV-1 protease inhibitors.

Several small, achiral nonpeptide inhibitors of HIV-1 protease with low micromolar activity were identified by mass screening of the Parke-Davis compound library. Two of the compounds, structurally similar, were both found to be competitive and reversible inhibitors [compound 1, 4-hydroxy-3-(3-phenoxypropyl)-1-benzopyran-2-one: Ki = 1.0 microM; compound 2, 4-hydroxy-6-phenyl-3-(phenylthio)-pyran-2-one: Ki = 1.1 microM]. These inhibitors were chosen as initial leads for optimization of in vitro inhibitory activity based on molecular modeling and X-ray crystallographic structural data. While improvements in inhibitory potency were small with analogues of compound 1, important X-ray crystallographic structural information of the enzyme-inhibitor complex was gained. When bound, 1 was found to displace H2O301 in the active site while hydrogen bonding to the catalytic Asps and Ile50 and Ile150. The pyranone group of compound 2 was found to bind at the active site in the same manner, with the 6-phenyl and the 3-phenylthio occupying P1 and P1', respectively. The structural information was used to develop design strategies to reach three or four of the internal pockets, P2-P2'. This work led to analogues of diverse structure with high potency (IC50 < 10 nM) that contain either one or no chiral centers and remain nonpeptide. The highly potent compounds possess less anti-HIV activity in cellular assays than expected, and current optimization now focuses on increasing cellular activity. The value of the HIV-1 protease inhibitors described is their potential as better pharmacological agents with a different pattern of viral resistance development, relative to the peptide inhibitors in human clinical trials.