Characterization of cloned alpha-satellite sequence from the extrachromosomal DNA of HeLa cell culture]

We have obtained the alphoid DNA clones, pK1 and pK2, from the extrachromosomal DNA of Hela cells treated by cycloheximide (30 micrograms/ml). Nucleotide sequences of the clones were aligned. The sides of the pK1 and pK2 are 390 and 184 bp, respectively. The marked RELP for the clones was not observed. The results of in situ hybridization have shown an approximately equal distribution of Ag-grains over major part of human chromosomes, with a slight preference for chromosomes 1, 5 and 19 (the 1-st group of alpha-satellite DNA). Therefore, the obtained alphoid sequences seem to be rather conservative and non-chromosome-specific. We suppose that increase of the alphoid DNA content in the fraction of the extrachromosomal DNA under the cycloheximide treatment is a result of the sporadic statistical processes rather then consequence of the specific excision.     

Cyclic AMP efflux is regulated by occupancy of the adenosine receptor in pig aortic smooth muscle cells

Cultured pig aortic smooth muscle cells respond to extracellular adenosine by activating adenylate cyclase and by initiating the efflux of cAMP. In the presence of extracellular adenosine, efflux is first order with respect to intracellular cAMP concentration up to at least 125 pmol/10(6) cells. The apparent first-order rate constant for the efflux of cAMP increases in a dose-dependent manner in response to extracellular adenosine or 5-N-ethylcarboxamide adenosine. The EC50 for adenosine for promoting cAMP efflux is 12 microM. For cells stimulated with 5-N-ethylcarboxamide adenosine, the EC50 is 5 microM. When extracellular adenosine is removed, efflux stops abruptly. Cellular cAMP content falls but is still in a range that supports cAMP efflux when agonist is present. Efflux is not affected by H8 (N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride), an inhibitor of cAMP-dependent protein kinase. These data suggest that in pig aortic smooth muscle cells, the efficiency of cAMP efflux is regulated by A2 receptor occupancy.     

Antiatherogenic action of corn oil in experimental atherosclerosis]

Therapeutic effect of corn oil was studied in rabbits with alimentary atherosclerosis. Corn oil was administered (2 ml/kg, 30 days) after the completion of cholesterol diet unlike studies, where they were administered simultaneously. Total cholesterol, apoB-lipoprotein cholesterol and triglycerides decreased more intensively in rabbits fed by corn oil than in control group. No changes in high-density lipoprotein cholesterol were observed. The most pronounced effect was noted in aorta morphological analysis: an aorta damage degree was 4.8% as compared with 52.9% in the control group. The results show that available plant oils with omega-6 polyunsaturated fatty acids (PUFA), in particular corn oil, may as well as omega-3 PUFA be used as the base for antiatherogenic preparations.     

Characterization of Propionibacterium plasmids

Plasmid DNAs from 15 Propionibacterium strains were characterized by using restriction endonuclease analyses, DNA-DNA hybridizations, and curing experiments. Restriction endonuclease analysis identified seven distinct plasmids (pRGO1 through pRGO7). Detailed restriction maps were constructed for four of these plasmids. DNA-DNA hybridization analysis revealed that plasmids pRGO1 and pRGO2 had extensive sequence homology and that both were homologous to pRGO7 and to similar sequences of pRGO5. Plasmids pRGO4 and pRGO6 did not have any significant sequence homology with any of the other plasmids. Plasmid pRGO3 had partial sequence homology only with pRGO7. Curing of plasmids pRGO1, pRGO2, and pRGO5 was achieved by treatment with acriflavin, but we failed to identify any plasmid-encoded bacteriocin production, carbohydrate fermentation, or antibiotic resistance. However, physical evidence was obtained that tentatively linked the clumping phenotype of Propionibacterium jensenii P38 with plasmid pRGO5.     

Zidovudine (azido dideoxythymidine) inhibits characteristic early alterations of lymphoid cell populations in retrovirus-induced murine AIDS

Using flow cytometry technology and multiparameter analyses, we report early and characteristic alterations in lymphoid cell profile in spleen and lymph nodes due to LP-BM5 retrovirus disease (murine AIDS (MAIDS)) and the effect of azido dideoxythymidine, a nucleoside inhibitor, on these changes. MAIDS has been characterized by rapid and profound lymphoproliferation accompanied by hypergammaglobulinemia and immunosuppression. As early as 2 wk postinfection, there is a selective depletion of CD8+ cells whereas the total number of CD4+ cells increases throughout the first 8 wk of infection although the frequency is relatively stable. These population changes were partially delayed by oral AZT therapy for 6 wk postinfection. Ly-6C (AL-21) is expressed on roughly 50% of CD4+ and CD8+ cells in C57BL/6 mice. In MAIDS, the residual population of CD8+ cells is primarily Ly-6C+. The CD4+ cells have a transient increase in ratio of Ly-6C+/Ly-6C- cells at 2 wk postinfection but by 6 wk are primarily Ly-6C-. There was an increase in both the total number and percentage of Mac 1+ cells and a selective depletion of certain splenic B cell subpopulations. Azido dideoxythymidine delays these early population changes.     

Cross-linkage sites in type I collagen fibrils studied by neutron diffraction

Cross-links in tendon collagen are essential for the biomechanical strength of healthy tissue. The nature and position of these cross-links has long been a subject for conjecture. We have approached this problem in a non-destructive manner, by studying neutron diffraction from collagen fibrils that have been specifically deuterated by reduction at keto-amine and Schiff base groups with sodium borodeuteride (NaB2H4). The intensities of the first 23 meridional reflections were recorded for both native and reduced tendons. These data were used to calculate the neutron-scattering density profile of the 67 nm (D) repeat of type I collagen fibrils in rat tail tendon. This approach not only succeeds in determining the location of the cross-linkage sites with respect to the fibril structure, as projected onto the fibre axis, but also presents a novel form of the isomorphous derivative solution to the phase problem.     

Neurophysins as markers of vasopressin and oxytocin release. A study in carcinoma of the lung

Vasopressin-neurophysin (hNpI), oxytocin-neurophysin (hNpII) and blood osmolality were assayed before any treatment in basal conditions in 35 patients suffering from lung carcinoma (20 oat cell, 6 undifferentiated and 9 well-differentiated epidermoid cell carcinomas). Plasma vasopressin (antidiuretic hormone, ADH) was also assayed in 7 of the 20 patients suffering from oat cell carcinoma. We found a close correlation (r = 0.98) between plasma ADH and hNpI levels in the 7 patients. Further, hNpI was elevated in 13 out of the 20 oat cell carcinoma patients and in none of the epidermoid-cell carcinoma group; however, searching for an abnormality of ADH secretion as reflected by a detectable plasma hNpI level together with subnormal plasma osmolality revealed 2 additional positive results in the oat cell carcinoma group, and 2 out of the 6 in the undifferentiated-cell carcinoma group. hNpII was increased together with an increase in hNpI in 6 oat cell carcinoma patients; it was specifically increased without hNpI increment in 2 additional oat cell carcinoma patients and in 2 patients of the undifferentiated-cell carcinoma group (different from the 2 positive for the hNpI-osmolality ratio). hNpI and hNpII were normal in the majority of undifferentiated and all of the differentiated epidermoid-cell carcinoma group. Hence, our results show that simultaneous measurements of hNpI, hNpII, and blood osmolality could detect abnormalities in 17 out of 20 oat cell carcinoma patients, in 4 of the 9 undifferentiated-cell carcinoma patients, but in none of the differentiated epidermoid-cell carcinoma patients, suggesting that the neurophysin assay can be used for the early detection of oat cell- and possibly other neuroendocrine-derived carcinomas.     

Reinvestigation of phosphorylation of tRNA in Escherichia coli.

This report shows the results of the reinvestigation of tRNA phosphorylation in E. coli. The phosphorylation did not occur on suppressor seryl-tRNA but occurred on other tRNA species. The activity of tRNA phosphorylation was found in E. coli extracts and partially purified. On DEAE-Sephadex A50 and PAGE gel, the phosphorylated-tRNA showed a pattern different from that the natural suppressor serine tRNA.     

Chemo- and karyotaxonomic studies on some rhizomatous species of the genusSymphytum (Boraginaceae)

InS. tuberosum subspp.tuberosum andnodosum, S. grandiflorum andS. ibericum the presence of the pyrrolizidine alkaloids lycopsamine, echimidine and symphytine could be demonstrated. The taxonS. tuberosum contains an unknown compound that seems to be specific for this taxon. This compound is not the pyrrolizidine alkaloid anadoline which has previously been reported for this species. It is possibly represented by a peak on GC/MS with a molecular ion peak at m/z 623 (as TMS derivative) and can be used as a chemotaxonomic marker for the speciesS. tuberosum. The pyrrolizidine alkaloid pattern of the two subspecies ofS. tuberosum reinforces the close relationship. Fresh material ofS. tuberosum contained the triterpene isobauerenol, but in herbarium material isobauerenol was lacking. InS. grandiflorum, neither fresh nor dried material contains isobauerenol. In herbarium material ofS. ibericum also no isobauerenol could be found. More extensive chemotaxonomical research is necessary to support the view thatS. abchasicum is more closely related toS. ibericum than toS. grandiflorum.