Myeloperoxidase-mediated oxidation of high-density lipoproteins: fingerprints of newly recognized potential proatherogenic lipoproteins

Substantial evidence supports the notion that oxidative processes participate in the pathogenesis of atherosclerotic heart disease. Major evidence for myeloperoxidase (MPO) as enzymatic catalyst for oxidative modification of lipoproteins in the artery wall has been suggested in numerous studies performed with low-density lipoprotein. In contrast to low-density lipoprotein, plasma levels of high-density lipoprotein (HDL)-cholesterol and apoAI, the major apolipoprotein of HDL, inversely correlate with the risk of developing coronary artery disease. These antiatherosclerotic effects are attributed mainly to HDL's capacity to transport excess cholesterol from arterial wall cells to the liver during 'reverse cholesterol transport'. There is now strong evidence that HDL is a selective in vivo target for MPO-catalyzed oxidation impairing the cardioprotective and antiinflammatory capacity of this antiatherogenic lipoprotein. MPO is enzymatically active in human lesion material and was found to be associated with HDL extracted from human atheroma. MPO-catalyzed oxidation products are highly enriched in circulating HDL from individuals with cardiovascular disease where MPO concentrations are also increased. The oxidative potential of MPO involves an array of intermediate-generated reactive oxygen and reactive nitrogen species and the ability of MPO to generate chlorinating oxidants-in particular hypochlorous acid/hypochlorite-under physiological conditions is a unique and defining activity for this enzyme. All these MPO-generated reactive products may affect structure and function of HDL as well as the activity of HDL-associated enzymes involved in conversion and remodeling of the lipoprotein particle, and represent clinically useful markers for atherosclerosis.     

Quantitative measurement of 5-, 12-, and 15-hydroxyeicosatetraenoic acid together with 12-hydroxyheptadecatrienoic acid by stable isotope dilution gas chromatography-negative ion chemical ionization-mass spectrometry

A stable isotope dilution gas chromatography-negative ion chemical ionization-mass spectrometry assay for simultaneous quantitative measurement of 5-hydroxyeicosatetraenoic acid (HETE), 12-HETE, 15-HETE, and 12-hydroxyheptadecatrienoic acid in one single GC/MS run was established. 18O2-Labeled analogs as internal standards, prepared according to conventional procedures, were found to be useful for this application. A sample processing and derivatization sequence providing highly purified compounds with a recovery of 42.7% was elaborated. The detection limit was in the femtomole range.     

Variation in Potentilla sect. Aureae (Rosaceae) in the Baltic states

The morphological variation of four Baltic representatives of the genus Potentilla section Aurea–P. neumanniana, P. arenaria, P. subarenaria and P. crantzii was studied with multivariate methods. Altogether 41 characters were used. The most important characters for the phenetical classification are those of the epidermis: characters of stellate and glandular hairs and numbers of cells. Macromorphological characters are less important, the most useful of these being the length of sepals and stipules and the number of teeth of the central leaflet. All four species are significantly distinct. Even P. subarenaria, a putative hybrid of P. arenaria and P. neumanniana, is clearly separated. At the same time, the species are morphologically quite variable, and it is possible to distinguish subclusters (morphotypes) within P. neumanniana, P. subarenaria and P. crantzii, which are also statistically distinct. The varieties described by Wolf (1908) under the name P. verna (P. neumanniana) do not agree well with the morphs in our material. However, it can be admitted that var. typica and var. neumanniana axe prevalent, var. pseudo-incis? and var. incis? occur occasionally; only var. longifoli? can be quite clearly delimited.     

IgG antibodies to Lewis type 2 antigens in serum of H. pylori-infected and noninfected blood donors of different Lewis(a,b) blood-group phenotype

Individuals of the Le(b+)/secretor phenotype revealed a stronger natural immune response to Le(x) and Le(y) epitopes irrespective of Helicobacter pylori serologic status. In contrast, H. pylori-infected Le(b-) type individuals showed a significantly higher proportion of strong responders to Le(x) antigen compared with the H. pylori-uninfected subgroup. The data suggest that the immune response to Lewis type 2 determinants is related to both the H. pylori serologic status and the Le(a,b) phenotype of the host.     

Phylogenetic relationships between and within sections Hypechusa, Narbonensis and Peregrinae of genus Vicia (Fabaceae) based on evidence from isozymes and morphology

Previous studies of vetch species belonging to sections Hypechusa, Narbonensis and Peregrinae have revealed controversies and open questions that deserve revisiting with the use of contemporary approaches. The paper extends the previous work of Leht and Jaaska (2002) by describing variation of 16 isozymes and 86 morphological characters among 17 Vicia species belonging to sections Hypechusa, Narbonensis and Peregrinae of the type subgenus in comparison with V. bithynica of section Pseudolathyrus. Three more isozymes and 12 new morphological characters are included to improve the resolution of phylogenetic relationships. The maximum parsimony trees based on isozymes and morphology revealed essentially the same four clusters of species that correspond to series Hypechusa and Hyrcanicae of section Hypechusa, to sections Narbonensis and Peregrinae of current taxonomy, except that the isozyme tree placed V. lutea of series Hypechusa into a separate clade. Isozyme variation in V. mollis, V. noeana, V. sericocarpa and V. ciliatula of section Hypechusa is described for the first time. Twenty-three species-specific isozymes that may be used for species identification by analysis of seeds are described. Two new isozymes that distinguish V. serratifolia from V. narbonensis are described that further support their specific status. Series Hypechusa and Hyrcanicae of section Hypechusa, sections Narbonensis and Peregrinae of traditional taxonomy are monophyletic groups that deserve sectional status within the genus Vicia. The phylogenetic position and sectional placement of V. lutea warrants further study with independent sets of DNA characters.     

The Seasonal Dynamics and Trophic Relations of the Plankton Components in Lake Peipsi (Peipus)

The seasonal dynamics of the biomass and production of phyto-, zoo- and bacterioplankton was investigated during the vegetation periods (from May to November) in 1985 and 1986 in the pelagial of the large eutrophic lake Peipsi (Estonia). The average values of productions per vegetation period for the investigation years were as follows: phytoplanktion − 203.5 gC · m⁻²; bacterioplankton − 37.9 gC · m⁻²; filter-feeding zooplankton − 20.6 gC · m⁻² and predatory zooplankton − 1.5 gC · m⁻². The herbivorous zooplankton production constituted 10.1% of primary production. This ratio indicates a direct relationship between zoo- and phytoplankton in the food chain — filtrators are feeding mostly on living algae and the detrital food chain seems of little importance. The dominance of large forms (Melosira sp., Aphanothece saxicola), in the phytoplankton during the major part of the vegetation period is assumed to be a result of high grazing pressure on small algae. Zooplankton grazing was investigated in situ in a specially constructed twin bathometer. Experimental measurements revealed, that zooplanktion presence in the experimental vessel actually stimulated the phytoplankton growth in many cases — the negative grazing values have been registered. That could be caused by the stimulation effect of nutrients (N, P), excreted by the concentrated zooplankton in the grazing chamber, which led to an increase of the nongrazed phytoplankton production. Bacteria have satisfied the zooplankton food requirements on average by 11%. Grazing on bacteria increased, when grazing on phytoplankton was somehow disturbed.     

Hybrid aspens responses to alkalisation of soil: growth, leaf structure, photosynthetic rate and carbohydrates

Interactions between photosynthetic rate, transpiration, content of soluble carbohydrates, leaf dimensions and structural parameters and growth of hybrid aspen (Populus tremula?×?P. tremuloides Michx.) were studied in relation to soil pH and chemical composition. The investigations were conducted in two plantations on former agricultural lands in North Estonia. One plantation was established on a territory influenced for a long time by alkaline cement dust pollution before plantation establishment and the other on an unpolluted territory. At pH 7.4 and higher concentrations of Ca, K, Mg, N and P in soil on the polluted area inhibition of height growth and diameter at breast height, leaf area and dry mass was observed compared to the unpolluted plantation with an optimum soil pH of 6.7. Differences in hybrid aspen leaves in the two plantations were related to the lower net photosynthetic and transpiration rates and higher starch and sucrose contents in the polluted plantation. Leaves from alkaline soil had a thicker palisade mesophyll layer and lower number of stomata at abaxial epidermis. The relatively low N concentration in leaves in the polluted area was associated with the low height and diameter at breast height of trees.