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A D Dmitriev

Publications and source records attributed to A D Dmitriev.

52 records · Page 3Linked to original sources
PubMed1976

[Reversion of RNA-polymerase mutations affecting F'-factor stability].

Ts+ reversions of amber mutations tsR on the beta-subunit of Escherichia coli RNA polymerase (79 min on the genetic map) were investigated. TsR mutants are viable due to the partial suppression of amber mutations by su2 suppressor. Three types of reversions were isolated in the course of the selection for Ts+ character, namely, intragenic reversions and two types of extragenic reversions, located at different regions of the bacterial chromosome. The mutation N5, located between 0 and 15 min. on the map, increases practically to normal the amount of RNA polymerase beta-polypeptide, which is diminished as a result of ts22 amber mutation action, and increases the plating efficiency of several T4 phage amber mutants. The mutations designated as D are located on the chromosome near the spcA locus (64 min. on the E. coli map). These mutations are characterized by pleiotropic effect. They have properties of a weak suppressor increasing the efficiency of su2 action on amber mutations of E. coli and phage T4. At the same time D mutations are capable to decrease sharply the efficiency of the crosses with F' strains. Both these characters determined by D mutations do not segregate in transduction. It is suggested that the decrease of sexduction by D mutations depends on their influence on replication of episomes in the recipient cells.

Chromosome Mapping↗
PubMedDate not supplied

[The binding of bispecific monoclonal antibodies to the solid phase-adsorbed antigens].

The ability of bispecific antibodies (Babs) formed by fusion of hybridomas and parent monoclonal antibodies (Mabs) to interact with the solid phase-adsorbed antigens was studied. Mabs specific to the three different antigens [horseradish peroxidase (HRP), human IgG (hIgG), and human myoglobin (Mb)] as well as Babs with the double specificity [antimyoglobin/antiperoxidase (anti-Mb/HRP) and anti-hIgG/antiperoxidase (anti-hIgG/HRP)] were used. It was shown by radioimmunological and immunoenzyme assays that parent Mabs bind to solid phase-adsorbed antigens considerably more effectively than Babs. The observed equilibrium binding constant (Ka) of antiperoxidase parental Mabs to immobilized HRP is 21 and 38 times higher than Ka for Babs binding sites (anti-Mb/HRP and anti-hIgG/HRP, respectively) to peroxidase. It was calculated that about 90-95% of all bound parental antiperoxidase Mabs were associated with immobilized HRP bivalently, and only about 5-10% were bound monovalently. On the contrary, parental Mabs against hIgG bind to the sorbed antigen essentially only monovalently. It was also shown that the avidity of anti-Mb/HRP Babs significantly increased when two antigens, Mb and HRP, were simultaneously adsorbed on the solid phase. These data imply that Babs bearing an enzyme-binding site (for example, binding to HRP) cannot be more effective than standard conjugates (e.g., enzyme-conjugated antibodies) in heterogeneous noncompetitive immunoassays.

Animals↗
PubMedDate not supplied

[The endorphins of the epithelial and subepithelial structures of the rat small intestine and the evolutionary hypotheses of the formation of the mechanisms of the negative regulation of their synthesis].

The effects of the agonist of the glucocorticoid hormones dexamethasone and dopamine antagonist--haloperidol on the concentration of immunoreactive alpha-, beta- and gamma-endorphins in duodenum, ileum, and jejunum of rats were studied. Besides the extracts of the intestines, the immunoreactive endorphins were measured in the extracts of their mucosa-submucosa and muscle-serous layers, that allowed to separate the endorphin-producing cells of the nervous system (muscle-serous layer) from endorphin producing cells of endocrine and immune systems (mucosa-submucosa layer). The injection of dexamethasone (0.2 mg per rat, daily for 6 days) caused the reliable decrease in concentrations of all three types of endorphins in mucosa-submucosa and muscle-serous layer of duodenum, ileum, and jejunum. Under the action of haloperidol (0.6 mg per rat, daily for 6 days) the reliable increase of beta-endorphin concentration was noticed only in jejunum. The suggestion is made that two distinct subpopulations of endorphin-producing cells exist in the intestine: in one cells endorphin synthesis is regulated by glucocorticoids, as in the anterior lobe of pituitary, in the other cells the synthesis of endorphins is regulated by dopamine, as in the cells of the intermediate lobe of pituitary. It is suggested that both glucocorticoid and dopamine types of regulation of endorphins synthesis were formed in the intestine or even in the gastric cavity. In process of evolution the cells with glucocorticoid type of regulation gave rise to the anterior lobe of pituitary, the cells with the dopamine type of regulation--to the intermediate lobe.

Adrenalectomy↗
PubMedDate not supplied

[Radioimmunological assay of plasma levels of alpha-gamma-endorphins in healthy donors and patients with endogenous depression].

Radioimmunological procedure enabled to estimate alpha- and gamma-endorphins in human blood plasma without pre-extraction. Basal level of these neuropeptides in peripheric blood plasma of 18 healthy donors constituted: C alpha = 392 +/- 244 pg/ml and C gamma = 20.6 +/- 9.1 pg/ml. Content of these endorphins in blood plasma did not depend on age and sex. Concentration of alpha- and gamma-endorphins were shown to correlate in peripheric blood (r = 0.88); this suggests the overall mechanisms for regulation of their synthesis, secretion and degradation. At the same time, distinct differences in concentrations of alpha- and gamma-endorphins in blood plasma were not found in groups of healthy donors and of patients with endogenous psychoses and pronounced depressive symptoms.

Adolescent↗
PubMedDate not supplied

[Effect of several factors on synthesis of RNA-polymerase subunits by Escherichia coli K12].

In merodiploid cells containing a double dose of structural genes of RNA polymerase subunits--rpoB and rpoC--the rate of synthesis of beta- and beta'-subunits is 2 times higher than in haploid cells. Missense mutation rpoC1 (tsX) in the beta'-polypeptide gene accelerates the synthesis of both beta- and beta'-subunits, particularly at a nonpermissive temperature. When rpoB-rpoC operon containing mutation rpoC1 is duplicated no dose effect of these genes is observed. In the heterozygous state mutation rpoC1 produces almost no accelerating effect on the synthesis of RNA polymerase subunits i. e. is recessive with respect to the wild allele of rpoC. In the presence of rifampicin the synthesis of RNA polymerase subunits in a sensitive wild-type strain is stimulated 6-fold, the same effect is observed with cells carrying mutation rpoC1, the latter, however, itself accelerates the synthesis of these subunits 3-fold. Thus the effects of rifampicin and the mutation are synergistic indicating that these factors act independently. Similar data have also been obtained with rifampicin-treated cells of rpoB22 amber-mutant. In UV-irradiated cells, amino acid incorporation into beta- and beta'-subunits declines more rapidly than into the total protein. When either irradiated or non-irradiated cells are infected with a transducing phage lambdarifd-47 which carries rpoB gene, the synthesis of beta-proceeds at a higher rate. Irradiation of bacteria before the infection (500 erg/mm2) results in 6.5-fold acceleration of the synthesis induced by subsequent infection with lambdarifd-47 as compared to non-infected non-irradiated cells; the fraction of newly formed beta-polypeptide with respect to total protein grows 20-fold in this case. The data are considered with regard to the possible mechanisms of regulation of synthesis of RNA polymerase subunits.

Bacterial Proteins↗
PubMedDate not supplied

[Effect of stress, infarction and adaptation to brief exposure to stress on opioid peptide levels in the brain].

Content of beta-endorphine, Met- and Leu-encephalines was studied in various brain regions and in adrenal glands after long-term immobilization stress, after myocardial infarction and during prolonged gradual adaptation to short-term stressory affects. Acute stressory conditions, myocardial infarction or, especially distinct adaptation to short-term stressory affects were shown to cause an accumulation of opioid peptides in brain structures and in adrenal glands. This increase in opioid peptides accumulated as a tissue reserve appears to elevate the body resistance to subsequent injuring affects.

Adrenal Glands↗
PubMedDate not supplied

[Factor from rat and bovine pineal organs immunologically and biologically related to luliberin].

Luteinizing hormone releasing hormone (LH-RH, luliberin) was revealed in the pineal organs of rats and cattle. The luliberin content per organ varied in rats from 5 to 66 ng, depending on sex and age. In some cases it could not be revealed by the direct radioimmunological method in the organ extracts, while neurohormone was detected by chromatography on carboxymethylcellulose or on Sephadex G-15. About 0.5 ng of LH-RH is contained in the bocine pineal organs, and the neurohormone competed with 125I-LH-RH for binding with a specific antiserum in the same way as synthetic luliberin. Mobility of LH-RH from the bovine and rat pineal organs during carboxymethylcellulose chromatography in the column coincided with such for synthetic LH-RH and the neurohormone from the rat hypothalamus. Besides, luliberin from the bovine pineal glands injected intraperitoneally to rats led to elevation of the LH blood level. No such effect occurred when luliberin from the epiphyses was preliminarily incubated with the LH-RH antiserum. A possible role played by luliberin in the pineal organ is discussed.

Age Factors↗