Conformational studies of plasminogen activator inhibitor type 1 by fluorescence spectroscopy. Analysis of the reactive centre of inhibitory and substrate forms, and of their respective reactive-centre cleaved forms.

The inhibitors that belong to the serpin family are suicide inhibitors that control the major proteolytic cascades in eucaryotes. Recent data suggest that serpin inhibition involves reactive centre cleavage followed by loop insertion, whereby the covalently linked protease is translocated away from the initial docking site. However under certain circumstances, serpins can also be cleaved like a substrate by target proteases. In this report we have studied the conformation of the reactive centre of plasminogen activator inhibitor type 1 (PAI-1) mutants with inhibitory and substrate properties. The polarized steady-state and time-resolved fluorescence anisotropies were determined for BODIPY(R) probes attached to the P1' and P3 positions of the substrate and active forms of PAI-1. The fluorescence data suggest an extended orientational freedom of the probe in the reactive centre of the substrate form as compared to the active form, revealing that the conformation of the reactive centres differ. The intramolecular distance between the P1' and P3 residues in reactive centre cleaved inhibitory and substrate mutants of PAI-1, were determined by using the donor-donor energy migration (DDEM) method. The distances found were 57+/-4 A and 63+/-3 A, respectively, which is comparable to the distance obtained between the same residues when PAI-1 is in complex with urokinase-type plasminogen activator (uPA). Following reactive centre cleavage, our data suggest that the core of the inhibitory and substrate forms possesses an inherited ability of fully inserting the reactive centre loop into beta-sheet A. In the inhibitory forms of PAI-1 forming serpin-protease complexes, this ability leads to a translocation of the cognate protease from one pole of the inhibitor to the opposite one.     

Circulating Autoantibodies against the Apolipoprotein B-100 Peptides p45 and p210 in Relation to the Occurrence of Carotid Plaques in 64-Year-Old Women

Objectives

Immune responses against oxidized low density lipoprotein (LDL) play a key role in atherosclerosis. Previous studies have indicated inverse associations between autoantibodies to epitopes in oxidized LDL and cardiovascular disease. In this study we investigated the associations between autoantibodies against the apolipoprotein B-100 (apoB-100) peptides p45 and p210 and occurrence of carotid plaques.

Design

The study cohort consisted of a population-based sample of 64-year-old women with varying degrees of glucose tolerance (n=594). To identify and record the occurrence of carotid atherosclerotic plaques ultrasonography was used. Measurements of plasma IgM and IgG autoantibodies against the native and malondialdehyde (MDA)-modified apoB-100 peptides p45 and p210 were performed by ELISA.

Results

Women with carotid plaques were found to have lower levels of IgM MDA-p210 autoantibodies compared to plaque-free women. The number of carotid plaques in each subject and the total carotid plaque area correlated inversely with IgM MDA-p210 levels (r=-0.11, P=0.009 and r=-0.11, P=0.013, respectively). Furthermore, levels of IgM MDA-p210 above the lowest tertile were associated with an odds ratio of 0.55 (95% CI 0.38-0.79, P=0.001) for occurrence of carotid plaques, independently of other risk markers and statin treatment. Associations between apo-B100 peptide autoantibodies and cardiovascular risk factors were generally weak but subjects with impaired glucose tolerance had higher levels of IgM against MDA-p210.

Conclusion

The present study demonstrates that high levels of IgM against MDA-p210 are associated with less severe carotid disease in women. These findings provide additional support for a role of immune responses against oxidized LDL in cardiovascular disease.     

Intraspecific Autochthonous and Allochthonous Resource Use by Zooplankton in a Humic Lake during the Transitions between Winter,Summer and Fall

Seasonal patterns in assimilation of externally produced, allochthonous, organic matter into aquatic food webs are poorly understood, especially in brown-water lakes. We studied the allochthony (share biomass of terrestrial origin) in cladoceran, calanoid and cyclopoid micro-crustacean zooplankton from late winter to fall during two years in a small humic lake (Sweden). The use of allochthonous resources was important for sustaining a small population of calanoids in the water column during late winter. However, in summer the calanoids shifted to 100% herbivory, increasing their biomass several-fold by making efficient use of the pelagic primary production. In contrast, the cyclopoids and cladocerans remained at high levels of allochthony throughout the seasons, both groups showing the mean allochthony of 0.56 (range in mean 0.17-0.79 and 0.34-0.75, for the respective group, depending on model parameters). Our study shows that terrestrial organic matter can be an important resource for cyclopoids and cladocerans on an annual basis, forming a significant link between terrestrial organic matter and the higher trophic levels of the food web, but it can also be important for sustaining otherwise herbivorous calanoids during periods of low primary production in late winter.     

Rapid speciation in a newly opened postglacial marine environment, the Baltic Sea

Background  

Theory predicts that speciation can be quite rapid. Previous examples comprise a wide range of organisms such as sockeye salmon, polyploid hybrid plants, fruit flies and cichlid fishes. However, few studies have shown natural examples of rapid evolution giving rise to new species in marine environments.     

The index herd with PMWS in Sweden: Presence of serum amyloid A,circovirus 2 viral load and antibody levels in healthy and PMWS-affected pigs

Background  

Postweaning Multisystemic Wasting Syndrome (PMWS) is an emerging disease in pigs of multifactorial origin, but associated to porcine circovirus type 2 (PCV2) infection. PMWS was first diagnosed in Sweden at a progeny test station that received pigs aged five weeks from 19 different nucleus herds on the day after weaning. The objective of this study was to examine, for the first time in an index outbreak of PMWS, the relationship between PCV2 virus, antibodies to PCV2 and serum amyloid a (SAA) in sequentially collected serum samples from pigs with and without signs of PMWS.     

Coevolution of non-fertile sperm and female receptivity in a butterfly

Sexual conflict can promote rapid evolution of male and female reproductive traits. Males of many polyandrous butterflies transfer nutrients at mating that enhances female fecundity, but generates sexual conflict over female remating due to sperm competition. Butterflies produce both normal fertilizing sperm and large numbers of non-fertile sperm. In the green-veined white butterfly, Pieris napi, non-fertile sperm fill the females'' sperm storage organ, switching off receptivity and thereby reducing female remating. There is genetic variation in the number of non-fertile sperm stored, which directly relates to the female''s refractory period. There is also genetic variation in males'' sperm production. Here, we show that females'' refractory period and males'' sperm production are genetically correlated using quantitative genetic and selection experiments. Thus selection on male manipulation may increase the frequency of susceptible females to such manipulations as a correlated response and vice versa.     

Multicellular Tumour Spheroid as a model for evaluation of [18F]FDG as biomarker for breast cancer treatment monitoring

Background  

In order to explore a pre-clinical method to evaluate if [¹⁸F]FDG is valid for monitoring early response, we investigated the uptake of FDG in Multicellular tumour spheroids (MTS) without and with treatment with five routinely used chemotherapy agents in breast cancer.     

Design,synthesis and structure–activity relationships of zwitterionic spirocyclic compounds as potent CCR1 antagonists

A series of zwitterionic spirocyclic compounds were synthesised. In vitro data revealed that these compounds were potent CCR1 antagonists. In particular, 2, 4, 11 and 20 inhibited CCR1 mediated chemotaxis of THP-1 cells in a functional assay.     

Borrelia pathogenesis research in the post-genomic and post-vaccine era

In the two years after publication of the genome sequence of Borrelia burgdorferi and reports on human field trials of a vaccine against Lyme borreliosis, there has been further progress in understanding of host-parasite interactions during Lyme borreliosis and relapsing fever. Some mechanisms that Borrelia spirochetes use to avoid elimination and to persist in the host are novel. In addition, the recent discovery of antigenic variation in the Lyme disease agent B. burgdorferi adds to the complexity of the possible virulence properties of this human pathogen.