Synthesis and properties of an organophosphorous regulator of hemoglobin oxygenation

Racemic 1-O-(epsilon-aminohexanoyl)-2,3-diphosphoglycerol (ADPG) was synthesized. The pH dependence of the 31P-NMR spectra was studied for the ADPG cyclohexylammonium salt. ADPG binding to hemoglobin and its functional activity as a regulator of human hemoglobin reversible oxygenation were assayed.     

Study of E. coli penicillin amidase. The pH dependence of the equilibrium constant of ampicillin enzymatic hydrolysis]

The equilibrium parameters of the hydrolysis of ampicillin catalysed by penicillin amidase were determined within the pH range of 4.5 to 5.5. The values of the ionization constants of the carboxy group of D-(-)-ALPHA-AMINOPHENYLACETIC ACID (PK1=1.80) and amino group of 6-aminopenicillanic acid (pK2=4.60) were estimated and pH-dependence of the effective free energy of ampicillin hydrolysis was calculated. It was shown that the thermodynamic optimum of ampicillin synthesis was at 3.20 (the value of the effective free energy under the experimental conditions was 3.27 kcal/mole). The value of the "true", pH-independent free energy of hydrolysis (deltasigma) of the amide bond in the ampicillin molecule was determined to be equal to 9.72 kcal/mole. The thermodynamic parameters of ampicillin and benzylpenicillin hydrolysis were compared. The amino group in the alpha-position of phenylacetic acid was shown to have a significant effect on the values of "true" free energy of hydrolysis of the penicillin amide bond and free ionization energy in the system.     

Physiologic characteristics of systems of conditioned connections during urgent formation of a program of action]

Examination of preschool age children has shown that instantaneous formation of a system is possible only on the basis of integration of conditioned reflexes, which are differentiated by the nature or strength of reinforcement. Integration of previously elaborated conditioned reflexes is more successful if the initial systems of conditioned connections were in a state of conditioned tonic excitation of an optimal strength. Uniformly strong or uniformly weak stability of all reflexes in the system renders it inert, hence makes it a poor basis for instantaneous formation of a new system.     

Effects of medium viscosity on kinetics of the enzymatic reaction catalyzed by bacterial RNase

Effects of medium viscosity on kinetic parameters of poly(U) hydrolysis catalyzed by RNase from Bac. intermedius 7P (binase) were studied in solutions of sucrose (4-50 wt. %) and glycerol (35-62 wt. %) in Tris--sodium acetate buffer (pH 7.5) at 25 degreesC. The rate constant of reaction kcat was practically unchanged over a wide range of viscosities (1-15 cP for sucrose and 2.5-3 cP for glycerol). In glycerol solutions, kcat slightly increased with viscosity increase from 4 to 10 cP. Addition of NaCl to the buffer medium resulted in an inhibitory effect of Na+ on kcat, prevented by 50% sucrose or 60% glycerol. It is concluded that binase-catalyzed poly(U) cleavage occurs through a "tense"-substrate mechanism, similarly to reactions catalyzed by alpha-chymotrypsin, trypsin, and laccase.     

Plasminogen activator and collagenase production by cultured capillary endothelial cells

Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.     

Successful immunotherapy with matrix metalloproteinase-derived peptides in adjuvant arthritis depends on the timing of peptide administration

We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development of such therapies.     

Granule-bound starch synthase: structure, function, and phylogenetic utility

Interest in the use of low-copy nuclear genes for phylogenetic analyses of plants has grown rapidly, because highly repetitive genes such as those commonly used are limited in number. Furthermore, because low- copy genes are subject to different evolutionary processes than are plastid genes or highly repetitive nuclear markers, they provide a valuable source of independent phylogenetic evidence. The gene for granule-bound starch synthase (GBSSI or waxy) exists in a single copy in nearly all plants examined so far. Our study of GBSSI had three parts: (1) Amino acid sequences were compared across a broad taxonomic range, including grasses, four dicotyledons, and the microbial homologs of GBSSI. Inferred structural information was used to aid in the alignment of these very divergent sequences. The informed alignments highlight amino acids that are conserved across all sequences, and demonstrate that structural motifs can be highly conserved in spite of marked divergence in amino acid sequence. (2) Maximum-likelihood (ML) analyses were used to examine exon sequence evolution throughout grasses. Differences in probabilities among substitution types and marked among-site rate variation contributed to the observed pattern of variation. Of the parameters examined in our set of likelihood models, the inclusion of among-site rate variation following a gamma distribution caused the greatest improvement in likelihood score. (3) We performed cladistic parsimony analyses of GBSSI sequences throughout grasses, within tribes, and within genera to examine the phylogenetic utility of the gene. Introns provide useful information among very closely related species, but quickly become difficult to align among more divergent taxa. Exons are variable enough to provide extensive resolution within the family, but with low bootstrap support. The combined results of amino acid sequence comparisons, maximum-likelihood analyses, and phylogenetic studies underscore factors that might affect phylogenetic reconstruction. In this case, accommodation of the variable rate of evolution among sites might be the first step in maximizing the phylogenetic utility of GBSSI.      

Morphologic changes in the sensomotor cortex in experimental neurosis

Disturbances of higher nervous activity (experimental neurosis) are attended with morphological changes of blood circulation in the sensorimotor area of the cerebral cortex, corresponding to distonic vascular disorders, as well as with hypoxic and neuroglial changes. Observed changes in the nervous tissue also reflect adaptive and defensive mechanisms of the brain (in rabbits).     

Comparative characteristics of new mesenchymal stem cell lines derived from human embryonic stem cells, bone marrow and foreskin

New nonimmortalized fibroblast-like cell lines SC5-MSC and SC3a-MSC, FetMSC, FRSN were obtained from human embryonic stem cells (ESC), bone marrow of a 5-6-days embryo and foreskin of a 3-years-old boy, respectively. All the lines are successfully used as the feeder at human ESC cultivation. It is determined that the average cell population doublings time varies from 25.5 h for ISC5-MSC to 38.8 h for SC3a-MSC. Active proliferation of all the lines is also shown by the corresponding growth curves. Numerical and structural karyotypic analysis showed that these lines had normal karyotype: 46,XX (SC5-MSC and SC3a-MSC) and 46,XY (FetMSC and FRSN). To determine the status of the lines, their cell surface markers were analyzed by flow cytometry. This analysis revealed the presence of surface antigens CD44, CD73, CD90, CD105 and HLA-ABC, characteristic of human MSC, and the absence of CD34 and HLA-DR. Different lines were found to express CD117(c-kit) to a different level. Immunofluorescence and flow cytometry analysis did not detect TRA-1-60 and Oct-4, characteristic of human embryonic stem cells, and revealed interlinear variations in the level of SSEA, which did not depend on the cell origin. It is not clear yet whether these interlinear variations affect functional MSC status. In all the lines, immunofluorescence analysis showed the presence of the markers of early differentiation in the derivates of three germ layers which may allow MSC to be useful, in corresponding microenvironments, for reparation of tissue injures. Adipogenic and osteogenic differentiatiation of all cell lines has been shown.