Quantitative estimation of lipid-laden cells in atherosclerotic lesions of the human aorta.

The intima of the adult human aorta consists of three sublayers: a muscular layer lying next to the media, a median hyperplastic layer and an innermost connective tissue layer, adjoining the lumen. The cells inhabiting these sublayers were isolated by the method of alcoholic-alkaline dissociation from grossly normal areas, fatty streaks and atherosclerotic plaques. The populations obtained contained cells with different numbers of cytoplasmic inclusions and a number without any. In unaffected intima and in fatty streaks, the cells with lipid inclusions were found predominantly in the outermost intimal layer including the connective tissue and in part of the median hyperplastic layer. In the superficial layer of unaffected intima and the fatty streak, these cells accounted for 15 and 25% of the total cell population, respectively. In the plaque, most cells with lipid inclusions were localized in the median hyperplastic layer of the intima (10%). The muscular layer was characterized by the lowest content of cells with lipid inclusions both in the unaffected intima and atherosclerotic lesions (from 0.75% in unaffected intima to 5% plaques). Among the intimal smooth muscle cells of various shapes, the cells with lipid inclusions were most often found in the stellate cell subpopulation (5-35%). A possible role of stellate cells in atherogenesis is discussed.     

Nucleotide sequence of the Yersinia pestis gene encoding F1 antigen and the primary structure of the protein. Putative T and B cell epitopes.

The plasmid-located gene caf1 encoding the capsular antigen fraction 1 (F1) of Yersinia pestis was cloned and sequenced. The gene codes for a 170 amino acid peptide with a deduced Mr of 17.6 kDa. The signal peptide sequence was highly homologous to the E. coli consensus signal sequence. The F1 was assumed to have beta-sheet structure for the most part. The region located between amino acids 100 and 150 was suggested to contain putative antigenic determinants and to stimulate T cells.     

Further characterization of recessive suppression in yeast. Isolation of the low-temperature sensitive mutant of Saccharomyces cerevisiae defective in the assembly of 60 S ribosomal subunit

It has been shown that recessive suppressor mutations in the yeast Saccharomyces cerevisiae may cause sensitivity towards low temperatures (very slow growth or lack of growth at 10 degrees C). One of the sup 1 low temperature sensitive (Lts-) mutants, 26-125A-P-2156, was studied in detail. After a prolonged period of incubation (70 h) under restrictive conditions the protein synthesis apparatus in the mutant cells was irreversibly damaged. In addition, Lts- cells incubated under restrictive conditions synthesize unequal amounts of ribosomal subunits, the level of 60 S subunit being reduced. It has been suggested that the recessive suppression is mediated by a mutation in the gene coding for 60 S subunit component, probably a ribosomal protein. The mutation leads simultaneously to a defect in the assembly of 60 S subunit and to low-temperature sensitive growth of the mutant.     

Incorporation of the ampicillin resistance transposon into the Escherichia coli K-12 chromosome and into plasmids]

The mutant pEG1 of R-factor RP4 with temperature-sensitive defect in replication, carrying a transposable ampicillin resistance element Tn1 was used to define the frequency of insertion of this element into Escherichia coli K-12 chromosome and some other plasmids. Our results indicate that the frequency of colony forming by bacteria with pEG1-factor on ampicillin medium in non-permissive conditions corresponds to the frequency of Tn1 insertion into bacterial chromosome or some other plasmid (in case when the strains are carrying a second plasmid). The frequency of Tn1 insertion into the chromosome is about 4.10(-4). The defect in recA gene produce no serious change in the frequency of Tn1 insertion into the bacterial chromosome. The translocation of Tn1 element from pEG1-factor to R483, R6 and ColE1 plasmids occurs at 10 to 100-fold-higher frequency than from the plasmid to the chromosome. The insertion of Tn1 into the F'-factor KLF10 and R-factor R64-11 occurs at far lower frequency than that to plasmids R6, R483, or ColE1.     

Radiosensitivity of somatic cells and imaginal disks of male and female Drosohila]

Primary chromosome damages as well as the frequency of spontaneous and X-rays induced chromosome aberrations in Drosophila melanogaster males and females are studied. It is found using cytofluorimetric method that primary chromosome damages in ganglia cells of females and males are the same. In these cells as well as in cells of imaginal discs the frequency of induced chromosome aberrations, except gaps, is considerably higher for females. Ganglia cells of females and males of Drosophila are found not to differ from each other in their proliferation activity. The frequency of morphoses for both sexes is also the same. The assumption is made concerning the role of the non-identical repair in the increased mutability of female somatic cells, which is more intensive in this sex, as well as concerning more intensive identical repair in imaginal discs of females.     

Formation kinetics of the AT-specific complex: DNA-distamycin A

The kinetics of DNA-distamycin A complex formation and dissociation was studied by means of the stop-flow method. It has been found that the complex formation has at least five steps, the formation of AT-specific complex is limited by the dissociation of less specific intermediate complexes, then follows the statistical rearrangement of the ligand molecules and "fixation" of the specific complex with the longest lifetime and the biggest number of the additional H-bounds with the matrix. The energy of a single specific H-bond between the ligand molecule and AT-pair is equal to--1.05 kcal/mol.     

Isolation of calcium pump system and purification of calcium ion-dependent ATPase from heart muscle.

The procedure for the isolation of the highly active fraction of sarcoplasmic reticulum from pigeon and dog hearts is described. The method is based on the partial loading of heart microsomes with calcium and oxalate ions and the precipitation of loaded vesicles in sucrose and potassium chloride concentration gradients. Preparations obtained possess high activity of Ca2+-dependent ATPase and are also able to accumulate up to 10 mumol Ca2+ per mg protein. Purification of sarcoplasmic reticulum membranes is accompanied by a decrease in concentration of cytochrome a+a3 and an increase in the content of [32P]phosphoenzyme. The basic components in "calcium-oxalate preparation" from hearts are proteins with molecular weights of about 100000 (Ca2+-dependent ATPase) and 55000 Calcium-oxalate preparation from pigeon hearts was used for subsequent purification of Ca2+-dependent ATPase. Specific activity of purified enzyme from pigeon hearts is 12-16 mumol Pi/min per mg protein. Enzyme activity of purified Ca2+-dependent ATPase is inhibited by EGTA and is not sensitive to azide, 2,4-dinitrophenol and ouabain. The data obtained demonstrate the similarity of calcium pump systems and Ca2+-dependent ATPases isolated from heart and skeletal muscles.