Vascular smooth muscle cell proliferation as a therapeutic target. Part 2: Natural products inhibiting proliferation

Many natural products have been so far tested regarding their potency to inhibit vascular smooth muscle cell proliferation, a process involved in atherosclerosis, pulmonary hypertension and restenosis. Compounds studied in vitro and in vivo as VSMC proliferation inhibitors include, for example indirubin-3′-monoxime, resveratrol, hyperoside, plumericin, pelargonidin, zerumbone and apamin. Moreover, taxol and rapamycin, the most prominent compounds applied in drug-eluting stents to counteract restenosis, are natural products. Numerous studies show that natural products have proven to yield effective inhibitors of vascular smooth muscle cell proliferation and ongoing research effort might result in the discovery of further clinically relevant compounds.     

Regeneration of diploid annual medics via direct somatic embryogenesis promoted by thidiazuron and benzylaminopurine

 The development of a simple and rapid procedure for direct somatic embryogenesis from wild Medicago spp. (M. truncatula, M. littoralis, M. murex, M. polymorpha) has exploited various explants including meristematic zones. Phytogel-solidified medium supplemented with thidiazuron or 6-benzylaminopurine at different concentrations effectively promoted this process. The first somatic structures emerged within 20 days of culture initiation. Histological analyses confirmed the nature of the directly formed embryos. Secondary embryogenesis was also observed. Cuttings of clusters of primary and secondary embryos were used for cyclic production of new embryo generations. Regenerated plants with well-developed root systems on medium with reduced levels of macroelements and sucrose were easily adapted to a greenhouse. Received: 23 March 1998 / Revision received: 10 August 1998 / Accepted: 7 December 1998     

Identification and characterization of acetyl-CoA carboxylase gene cluster in <Emphasis Type="Italic">Streptomyces toxytricini</Emphasis>

The gene locus for acetyl-CoA carboxylase (ACC) involved in the primary metabolism was identified from the genomic library of Streptomyces toxytricini which produces a lipase inhibitor lipstatin. The 7.4 kb cloned gene was comprised of 5 ORFs including accD1, accA1, hmgL, fadST1, and stsF. In order to confirm the biochemical characteristics of AccA1, the gene was overexpressed in Escherichia coli cells, and the recombinant protein was purified through Ni²⁺ affinity chromatography. Because most of the expressed AccAl was biotinylated by host E. coli BirA in the presence of D-biotin, the non-biotinylated apo-AccA1 was purified after gene induction without D-biotin, followed by exclusion of holo-AccA1 using streptavidin beads. The separated apo-AccA1 was post-translationally biotinylated by S. toxytricini biotin apo-protein ligase (BPL) in a time- and enzyme-dependent manner. This result supports that this gene cluster of S. toxytricini encodes the functional ACC enzyme subunits to be biotinylated.     

Proteomic Helicobacter pylori biomarkers discriminating between duodenal ulcer and gastric cancer

Protein patterns of 129 Helicobacter pylori strains isolated from Korean and Colombian patients suffering from duodenal ulcer or gastric cancer were analyzed by the high-throughput methodology SELDI-TOF-MS. Eighteen statistically significant candidate biomarkers discriminating between the two clinical outcomes were selected by using the Mann–Whitney test. Three biomarker proteins were purified and identified as a neutrophil-activating protein NapA (HU HPAG1_0821), a RNA-binding protein (HPAG1_0813), and a DNA-binding histone-like protein HU, respectively (jhp0228). These novel biomarkers can be used for development of diagnostic assays predicting the evolution to gastric cancer in H. pylori-infected patients.     

Sage in vitro cultures: a promising tool for the production of bioactive terpenes and phenolic substances

Extracts of Salvia species are used in traditional medicine to treat various diseases. The economic importance of this genus has increased in recent years due to evidence that some of its secondary metabolites have valuable pharmaceutical and nutraceutical properties.The bioactivity of sage extracts is mainly due to their content of terpenes and polyphenols. The increasing demand for sage products combined with environmental, ecological and climatic limitations on the production of sage metabolites from field-grown plants have led to extensive investigations into biotechnological approaches for the production of Salvia phytochemicals. The purpose of this review is to evaluate recent progress in investigations of sage in vitro systems as tools for producing important terpenoids and polyphenols and in development of methods for manipulating regulatory processes to enhance secondary metabolite production in such systems.     

Effect of 2,4-D precultivation on regeneration capacity of cultivated barley

Summary A reliable protocol for regeneration of barley from seedling explants including leaf bases with the complete apical meristem has been developed. Callus induction and shoot regeneration was only achieved when 28 days-old-seedlings were grown in the presence of high concentrations of 2,4-D. The Bulgarian barley variety Ruen commercially important for brewery industry was used as a model. The regeneration response of a range of Bulgarian barley genotypes was evaluated. Cytological analyses were performed at the level of callus and regenerants.Abreviations 2,4-D 2,4-Dichlorophenoxyacetic acid - IAA Indole-3-acetic acid - 2iP 6-(,-dimethylallylamino) purine     

UV irradiation as a tool for obtaining asymmetric somatic hybrids between Nicotiana plumbaginifolia and Lycopersicon esculentum

UV-irradiated kanamycin-resistant Lycopersicon esculentum leaf protoplasts were fused with wild-type Nicotiana plumbaginifolia leaf protoplasts. Hybrid calli were recovered after selection in kanamycin-containing medium and subsequently regenerated. Cytological analysis of these regenerants showed that several (2–4) tomato chromosomes, or chromosome fragments, were present in addition to a polyploid Nicotiana genome complement. All lines tested had neomycin phosphotransferase (NPTII) activity and the presence of the kanamycin gene was shown by Southern blotting. In two cases a different hybridization profile for the kanamycin gene, compared to the tomato donor partner, was observed, suggesting the occurence of intergenomic recombination events. The hybrid nature of the regenerants was further confirmed by Southern-blotting experiments using either a ribosomal DNA sequence or a tomato-specific repeat as probes. The hybrids were partially fertile and some progeny could be obtained. Our results demonstrate that UV irradiation is a valuable alternative for asymmetric cell-hybridization experiments. Received: 3 August 1996 / Accepted: 23 August 1996