Inter-annual trends of ultrafine particles in urban Europe

Ultrafine particles (UFP, those with diameters ≤ 100 nm), have been reported to potentially penetrate deeply into the respiratory system, translocate through the alveoli, and affect various organs, potentially correlating with increased mortality. The aim of this study is to assess long-term trends (5-11 years) in mostly urban UFP concentrations based on measurements of particle number size distributions (PNSD). Additionally, concentrations of other pollutants and meteorological variables were evaluated to support the interpretations. PNSD datasets from 12 urban background (UB), 5 traffic (TR), 3 suburban background (SUB) and 1 regional background (RB) sites in 15 European cities and 1 in the USA were evaluated. The non-parametric Theil-Sen's method was used to detect monotonic trends. Meta-analyses were carried out to assess the overall trends and those for different environments. The results showed significant decreases in NO, NO2, BC, CO, and particle concentrations in the Aitken (25-100 nm) and the Accumulation (100-800 nm) modes, suggesting a positive impact of the implementation of EURO 5/V and 6/VI vehicle standards on European air quality. The growing use of Diesel Particle Filters (DPFs) might also have clearly reduced exhaust emissions of BC, PM, and the Aitken and Accumulation mode particles. However, as reported by prior studies, there remains an issue of poor control of Nucleation mode particles (smaller than 25 nm), which are not fully reduced with current DPFs, without emission controls for semi-volatile organic compounds, and might have different origins than road traffic. Thus, contrasting trends for Nucleation mode particles were obtained across the cities studied. This mode also affected the UFP and total PNC trends because of the high proportion of Nucleation mode particles in both concentration ranges. It was also found that the urban temperature increasing trends might have also influenced those of PNC, Nucleation and Aitken modes.

Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observations

A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (babs) to eBC. This study investigates the spatial-temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and babs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2 g-1 from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2 g-1 from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasize the necessity of incorporating EC observations to constrain the uncertainty associated with eBC.

Residential Wood Combustion in Germany: A Twin-Site Study of Local Village Contributions to Particulate Pollutants and Their Potential Health Effects

Residential wood combustion contributing to airborne particulate matter (PM10) was studied for 1 year at two sites in the village of Melpitz. Significant excess pollution was observed at the Melpitz center compared to that at the TROPOS research station Melpitz reference site, situated only 700 m away. Local concentration increments at the village site for the combustion PM constituents organic carbon, elemental carbon, levoglucosan, and benzo[a]pyrene were determined under appropriate wind directions, and their winter mean values were 0.7 μg m-3, 0.3 μg m-3, 0.1 μg m-3, and 0.4 ng m-3, representing relative increases over the regional background concentration of 24, 70, 61, and 107%, respectively. Yearly, weekly, and diurnal profiles of village increments suggest residential heating as the dominant source of this excess pollution, mainly originating from wood combustion. Receptor modeling using positive matrix factorization quantified 4.5 μg m-3 wood combustion PM at the village site, representing an increment of 1.9 μg m-3 and an increase of ∼75% over the 2.6 μg m-3 regional background wood combustion PM. This increment varied with season, temperature, and boundary layer height and reached daily mean values of 4-6 μg m-3 during unfavorable meteorological conditions. Potential health effects were estimated and resulted in an all-cause mortality from short-term exposure to wood combustion PM of 2.1 cases per 100,000 inhabitants and year for areas with similar wood smoke levels as observed in Melpitz. The excess cancer risk from the concentrations of polycyclic aromatic hydrocarbons was 6.4 per 100,000. For both health metrics, the very local contributions from the village itself were about 40-50%, indicating a strong potential for mitigation through local-scale policies. A compilation of literature data demonstrates wood combustion to represent a major source of PM pollution in Germany, with average winter-time contributions of 10-20%. The present study quantifies the negative impacts of heating with wood in rural residential areas, where the continuous monitoring of air quality is typically lacking. Further regulation of this PM source is warranted in order to protect human health.

Ambient air particulate total lung deposited surface area (LDSA) levels in urban Europe

This study aims to picture the phenomenology of urban ambient total lung deposited surface area (LDSA) (including head/throat (HA), tracheobronchial (TB), and alveolar (ALV) regions) based on multiple path particle dosimetry (MPPD) model during 2017-2019 period collected from urban background (UB, n = 15), traffic (TR, n = 6), suburban background (SUB, n = 4), and regional background (RB, n = 1) monitoring sites in Europe (25) and USA (1). Briefly, the spatial-temporal distribution characteristics of the deposition of LDSA, including diel, weekly, and seasonal patterns, were analyzed. Then, the relationship between LDSA and other air quality metrics at each monitoring site was investigated. The result showed that the peak concentrations of LDSA at UB and TR sites are commonly observed in the morning (06:00-8:00 UTC) and late evening (19:00-22:00 UTC), coinciding with traffic rush hours, biomass burning, and atmospheric stagnation periods. The only LDSA night-time peaks are observed on weekends. Due to the variability of emission sources and meteorology, the seasonal variability of the LDSA concentration revealed significant differences (p = 0.01) between the four seasons at all monitoring sites. Meanwhile, the correlations of LDSA with other pollutant metrics suggested that Aitken and accumulation mode particles play a significant role in the total LDSA concentration. The results also indicated that the main proportion of total LDSA is attributed to the ALV fraction (50 %), followed by the TB (34 %) and HA (16 %). Overall, this study provides valuable information of LDSA as a predictor in epidemiological studies and for the first time presenting total LDSA in a variety of European urban environments.

The variability of mass concentrations and source apportionment analysis of equivalent black carbon across urban Europe

This study analyzed the variability of equivalent black carbon (eBC) mass concentrations and their sources in urban Europe to provide insights into the use of eBC as an advanced air quality (AQ) parameter for AQ standards. This study compiled eBC mass concentration datasets covering the period between 2006 and 2022 from 50 measurement stations, including 23 urban background (UB), 18 traffic (TR), 7 suburban (SUB), and 2 regional background (RB) sites. The results highlighted the need for the harmonization of eBC measurements to allow for direct comparisons between eBC mass concentrations measured across urban Europe. The eBC mass concentrations exhibited a decreasing trend as follows: TR > UB > SUB > RB. Furthermore, a clear decreasing trend in eBC concentrations was observed in the UB sites moving from Southern to Northern Europe. The eBC mass concentrations exhibited significant spatiotemporal heterogeneity, including marked differences in eBC mass concentration and variable contributions of pollution sources to bulk eBC between different cities. Seasonal patterns in eBC concentrations were also evident, with higher winter concentrations observed in a large proportion of cities, especially at UB and SUB sites. The contribution of eBC from fossil fuel combustion, mostly traffic (eBCT) was higher than that of residential and commercial sources (eBCRC) in all European sites studied. Nevertheless, eBCRC still had a substantial contribution to total eBC mass concentrations at a majority of the sites. eBC trend analysis revealed decreasing trends for eBCT over the last decade, while eBCRC remained relatively constant or even increased slightly in some cities.

Impact of ultrafine particles and total particle number concentration on five cause-specific hospital admission endpoints in three German cities

INTRODUCTION

Numerous studies have shown associations between daily concentrations of fine particles (e.g., particulate matter with an aerodynamic diameter ≤2.5 µm; PM2.5) and morbidity. However, evidence for ultrafine particles (UFP; particles with an aerodynamic diameter of 10-100 nm) remains conflicting. Therefore, we aimed to examine the short-term associations of UFP with five cause-specific hospital admission endpoints for Leipzig, Dresden, and Augsburg, Germany.

MATERIAL AND METHODS

We obtained daily counts of (cause-specific) cardiorespiratory hospital admissions between 2010 and 2017. Daily average concentrations of UFP, total particle number (PNC; 10-800 nm), and black carbon (BC) were measured at six sites; PM2.5 and nitrogen dioxide (NO2) were obtained from monitoring networks. We assessed immediate (lag 0-1), delayed (lag 2-4, lag 5-7), and cumulative (lag 0-7) effects by applying station-specific confounder-adjusted Poisson regression models. We then used a novel multi-level meta-analytical method to obtain pooled risk estimates. Finally, we performed two-pollutant models to investigate interdependencies between pollutants and examined possible effect modification by age, sex, and season.

RESULTS

UFP showed a delayed (lag 2-4) increase in respiratory hospital admissions of 0.69% [95% confidence interval (CI): -0.28%; 1.67%]. For other hospital admission endpoints, we found only suggestive results. Larger particle size fractions, such as accumulation mode particles (particles with an aerodynamic diameter of 100-800 nm), generally showed stronger effects (respiratory hospital admissions & lag 2-4: 1.55% [95% CI: 0.86%; 2.25%]). PM2.5 showed the most consistent associations for (cardio-)respiratory hospital admissions, whereas NO2 did not show any associations. Two-pollutant models showed independent effects of PM2.5 and BC. Moreover, higher risks have been observed for children.

CONCLUSIONS

We observed clear associations with PM2.5 but UFP or PNC did not show a clear association across different exposure windows and cause-specific hospital admissions. Further multi-center studies are needed using harmonized UFP measurements to draw definite conclusions on the health effects of UFP.

Impact of Ambient Ultrafine Particles on Cause-Specific Mortality in Three German Cities

Rationale: Exposure to ambient air pollution has been associated with adverse effects on morbidity and mortality. However, the evidence for ultrafine particles (UFPs; 10-100 nm) based on epidemiological studies remains scarce and inconsistent. Objectives: We examined associations between short-term exposures to UFPs and total particle number concentrations (PNCs; 10-800 nm) and cause-specific mortality in three German cities: Dresden, Leipzig, and Augsburg. Methods: We obtained daily counts of natural, cardiovascular, and respiratory mortality between 2010 and 2017. UFPs and PNCs were measured at six sites, and measurements of fine particulate matter (PM2.5; ⩽2.5 μm in aerodynamic diameter) and nitrogen dioxide were collected from routine monitoring. We applied station-specific confounder-adjusted Poisson regression models. We investigated air pollutant effects at aggregated lags (0-1, 2-4, 5-7, and 0-7 d after UFP exposure) and used a novel multilevel meta-analytical method to pool the results. Additionally, we assessed interdependencies between pollutants using two-pollutant models. Measurements and Main Results: For respiratory mortality, we found a delayed increase in relative risk of 4.46% (95% confidence interval, 1.52 to 7.48%) per 3,223-particles/cm3 increment 5-7 days after UFP exposure. Effects for PNCs showed smaller but comparable estimates consistent with the observation that the smallest UFP fractions showed the largest effects. No clear associations were found for cardiovascular or natural mortality. UFP effects were independent of PM2.5 in two-pollutant models. Conclusions: We found delayed effects for respiratory mortality within 1 week after exposure to UFPs and PNCs but no associations for natural or cardiovascular mortality. This finding adds to the evidence on the independent health effects of UFPs.

Phenomenology of ultrafine particle concentrations and size distribution across urban Europe

The 2017-2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus. The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN_10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN_10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping. Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation. PNC, especially PN_25-800, was positively correlated with BC, NO₂, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of <10 nm PNC are needed for full evaluation of the health effects of this size fraction.

Prevalence of Anaplasma phagocytophilum in small rodents in France

Anaplasma phagocytophilum is an emerging zoonotic tick-borne pathogen affecting a wide range of mammals. Rodents are suspected to be natural reservoirs for this bacterium, but their role in the epidemiologic cycles affecting domestic animals and wild ungulates has not been demonstrated. This study aimed to improve our knowledge on A. phagocytophilum prevalence in Apodemus sylvaticus, A. flavicollis and Myodes glareolus using data collected in 2010 in one area in eastern France and in 2012-2013 in two others areas in western France. Rodents were captured in each site and infection was tested using qualitative real-time PCR assays on either blood or spleen samples. Prevalence showed high variability among sites. The highest prevalence was observed in the most eastern site (with an average infection rate of 22.8% across all species), whereas no rodent was found to be PCR positive in the south-west site and only 6.6% were positive in the north-west of France. Finally, a significant increase in prevalence was observed in autumn samples compared to spring samples in the north-west, but no change was found in the other two sites.

Associations between ultrafine and fine particles and mortality in five central European cities - Results from the UFIREG study

BACKGROUND

Evidence on health effects of ultrafine particles (UFP) is still limited as they are usually not monitored routinely. The few epidemiological studies on UFP and (cause-specific) mortality so far have reported inconsistent results.

OBJECTIVES

The main objective of the UFIREG project was to investigate the short-term associations between UFP and fine particulate matter (PM)<2.5μm (PM2.5) and daily (cause-specific) mortality in five European Cities. We also examined the effects of PM<10μm (PM10) and coarse particles (PM2.5-10).

METHODS

UFP (20-100nm), PM and meteorological data were measured in Dresden and Augsburg (Germany), Prague (Czech Republic), Ljubljana (Slovenia) and Chernivtsi (Ukraine). Daily counts of natural and cardio-respiratory mortality were collected for all five cities. Depending on data availability, the following study periods were chosen: Augsburg and Dresden 2011-2012, Ljubljana and Prague 2012-2013, Chernivtsi 2013-March 2014. The associations between air pollutants and health outcomes were assessed using confounder-adjusted Poisson regression models examining single (lag 0-lag 5) and cumulative lags (lag 0-1, lag 2-5, and lag 0-5). City-specific estimates were pooled using meta-analyses methods.

RESULTS

Results indicated a delayed and prolonged association between UFP and respiratory mortality (9.9% [95%-confidence interval: -6.3%; 28.8%] increase in association with a 6-day average increase of 2750particles/cm(3) (average interquartile range across all cities)). Cardiovascular mortality increased by 3.0% [-2.7%; 9.1%] and 4.1% [0.4%; 8.0%] in association with a 12.4μg/m(3) and 4.7μg/m(3) increase in the PM2.5- and PM2.5-10-averages of lag 2-5.

CONCLUSIONS

We observed positive but not statistically significant associations between prolonged exposures to UFP and respiratory mortality, which were independent of particle mass exposures. Further multi-centre studies are needed investigating several years to produce more precise estimates on health effects of UFP.

[Health effects of ambient ultrafine particles--the project UFIREG]

BACKGROUND

The project "Ultrafine particles--an evidence based contribution to the development of regional and European environmental and health policy" (UFIREG) started in July 2011 and ended in December 2014. It was implemented through the Central Europe Programme and co-financed by the European Regional Development Fund. Five cities in four Central European countries participated in the study: Augsburg (Germany), Chernivtsi (Ukraine), Dresden (Germany), Ljubljana (Slovenia) and Prague (Czech Republic). The aim of the UFIREG project was to improve the knowledge base on possible health effects of ambient ultrafine particles (UFP) and to raise overall awareness of environmental and health care authorities and the population.

METHODS

Epidemiological studies in the frame of the UFIREG project have assessed the short-term effects of UFP on human mortality and morbidity, especially in relation to cardiovascular and respiratory diseases. Official statistics were used to determine the association between air pollution concentration and daily (cause-specific: respiratory and cardiovascular) hospital admissions and mortality. Associations of UFP levels and health effects were analysed for each city by use of Poisson regression models adjusting for a number of confounding factors.

RESULTS

Results on morbidity and mortality effects of UFP were heterogeneous across the five European cities investigated. Overall, an increase in respiratory hospital admissions and mortality could be detected for increases in UFP concentrations. Results on cardiovascular health were less conclusive.

CONCLUSION

Further multi-centre studies such as UFIREG are needed preferably investigating several years in order to produce powerful results.

Silencing of selected glutamate receptor subunits modulates cancer growth

BACKGROUND

Emerging evidence supports a role for glutamate in the biology of cancer. We studied the impact of glutamate receptor subunit silencing on cancer phenotype.

MATERIALS AND METHODS

Different fragments of the coding region for ionotropic glutamate receptor AMPA 4 (GLUR4), ionotropic glutamate receptor N-methyl D-aspartate 1 (NR1), ionotropic glutamate receptor kainate 5 (KA2) and ionotropic glutamate receptor N-methyl D-aspartate 2D (NR2D) were stably transfected into human TE671, RPMI8226 and A549 cell lines. Resulting changes in cell proliferation, migration and mRNA expression of genes that determine cancer phenotype were assayed.

RESULTS

Decreased expression of GLUR4 markedly increased cancer cell proliferation, whereas decreased expression of NR1 markedly reduced the propensity of cancer cells to proliferate. Knockdown of KA2 and NR2D did not influence cancer phenotype. Gene silencing of GLUR4 modulated the mRNA expression of various genes in these cancer cell lines, as determined with the Human Cancer PathwayFinder™ PCR Array. Knockdown of GLUR4 influenced the expression and function of genes involved in invasion and metastasis, tumour suppressor genes, oncogenes and adhesion genes.

CONCLUSION

The findings suggest that glutamate receptor subunits on cancer cells are linked to biochemical pathways that regulate malignant phenotype.

Toxicity of tungsten carbide and cobalt-doped tungsten carbide nanoparticles in mammalian cells in vitro

BACKGROUND

Tungsten carbide nanoparticles are being explored for their use in the manufacture of hard metals. To develop nanoparticles for broad applications, potential risks to human health and the environment should be evaluated and taken into consideration.

OBJECTIVE

We aimed to assess the toxicity of well-characterized tungsten carbide (WC) and cobalt-doped tungsten carbide (WC-Co) nanoparticle suspensions in an array of mammalian cells.

METHODS

We examined acute toxicity of WC and of WC-Co (10% weight content Co) nanoparticles in different human cell lines (lung, skin, and colon) as well as in rat neuronal and glial cells (i.e., primary neuronal and astroglial cultures and the oligodendrocyte precursor cell line OLN-93). Furthermore, using electron microscopy, we assessed whether nanoparticles can be taken up by living cells. We chose these in vitro systems in order to evaluate for potential toxicity of the nanoparticles in different mammalian organs (i.e., lung, skin, intestine, and brain).

RESULTS

Chemical-physical characterization confirmed that WC as well as WC-Co nanoparticles with a mean particle size of 145 nm form stable suspensions in serum-containing cell culture media. WC nanoparticles were not acutely toxic to the studied cell lines. However, cytotoxicity became apparent when particles were doped with Co. The most sensitive were astrocytes and colon epithelial cells. Cytotoxicity of WC-Co nanoparticles was higher than expected based on the ionic Co content of the particles. Analysis by electron microscopy demonstrated presence of WC nanoparticles within mammalian cells.

CONCLUSIONS

Our findings demonstrate that doping of WC nanoparticles with Co markedly increases their cytotoxic effect and that the presence of WC-Co in particulate form is essential to elicit this combinatorial effect.

Evaluation of a sensitive colorimetric FXIII incorporation assay. Effects of FXIII Val34Leu, plasma fibrinogen concentration and congenital FXIII deficiency

There is an increasing interest in the role of coagulation factor XIII (FXIII) in cardio- and cerebrovascular diseases. It has recently been reported that a common G-->T point mutation in the A-subunit gene of FXIII, which codes for a valine (val) to leucine (leu) change (FXIIIVal34Leu), is protective against thrombotic diseases but seems to increase the risk of intracerebral bleeding. We developed a colorimetric incorporation assay for detection of FXIII activity based on incorporation of 5-(biotinamido) pentylamine (BAPA) into fibrin or fibrinogen. With this new assay, we studied the effects of FXIIIVal34Leu mutation, plasma fibrinogen concentration and congenital FXIII deficiency on FXIII activity. There are no data available about the ability of different FXIII assays to detect altered activity in FXIIIVal34Leu genotypes. We therefore compared our results determined by the incorporation method with a commonly used photometric method based on ammonia release after cross-linking of glycine-ethylester to a specific glutamine containing peptide substrate. We also determined FXIII A-subunit antigen (Ag) levels using enzyme-linked immunosorbent assay (ELISA) technique. The FXIIIVal34Leu genotype could not be detected either by the photometric method nor by the FXIII A-subunit ELISA. The incorporation assay showed an increased specific FXIII activity in subjects possessing the leu allele. The photometric assay and ELISA gave similar results independent from genotype. In patients with congenital FXIII deficiency before and after substitution, however, ELISA and the incorporation assay gave similar results, whereas the photometric assay showed consistently higher values. Our results show that the incorporation assay, not the photometric assay based on ammonia release, can be used for detection of elevated activity in subjects with FXIIIVal34Leu. Because of specificity and over a wide range sensitivity, the assay can also be used for determination of FXIII deficiency and monitoring of FXIII substitution therapy.

Identification of a key region of kinin B(1) receptor for high affinity binding of peptide antagonists

To investigate the molecular basis for the specificity of ligand recognition in human kinin B(1) (B(1)R) and B(2) (B(2)R) receptors, we constructed a series of chimeric receptors by progressively replacing, from the N to the C terminus, the human B(2)R domains by their B(1) counterparts. The chimeric construct possessing the C-terminal tail and the transmembrane domain VII (TM VII) of the B(2)R (construct 6) displayed 7- and 20- fold decreased affinities for the B(1) agonist [(3)H]desArg(10)-kallidin (desArg(10)-KD) and the B(1) antagonist [(3)H]desArg(10)-[Leu(9)]-KD respectively, as compared with the wild-type B(1)R. Moreover, the substitution of the B(1) TM VII by its B(2) homologue TM increased the affinity for the pseudopeptide antagonists, Hoe140 and NPC 567. High affinity for desArg(10)-KD binding was fully regained when the B(2) residue Thr(287) was replaced in construct 6 by the corresponding B(1) Leu(294) residue. When the B(2) residue Tyr(295) was exchanged with the corresponding B(1) Phe(302), high affinity binding for both agonist and antagonist was recovered. Moreover, the L294T and F302Y mutant B(1)R exhibited 69- and 6.5-fold increases, respectively, in their affinities for the B(2) receptor antagonist, Hoe140. Therefore we proposed that Leu(294) and Phe(302) residues, which may not be directly involved in the binding of B(1)R ligands and, hence, their Thr(287) and Tyr(295) B(2) counterparts, are localized in a receptor region, which plays a pivotal role in the binding selectivity of the peptide or pseudopeptide kinin ligands.

Interleukin 8 (IL-8) induces the expression of kinin B1 receptor in human lung fibroblasts

Kinin B1 receptors are induced by various inflammatory mediators. The aim of the present study was to investigate the effect of the CXC chemokine IL-8 on kinin B1 receptor expression in IMR-90 cells, by performing binding studies and Northern blot analysis of B1 receptor mRNA levels. We demonstrated here that the density of the kinin B1 receptors could be increased by the chemokine IL-8 in a concentration- and time-dependent manner. IL-8 also increased the kinin B1 receptor mRNA level in IMR-90 cells. IL-8-induced B1 receptor expression could be totally abolished by pretreatment with the metabolic inhibitors. Furthermore, expression was markedly reduced by antibodies to human IL-1alpha. In conclusion, IL-8 increased the expression of kinin B1 receptors in IMR-90 cells and this effect is likely to be secondary to the production of IL-1beta.

Skeletal muscle ventricles: full versus half aortic ligation

BACKGROUND

Skeletal muscle ventricles have been shown to provide effective aortic diastolic counterpulsation in an experimental model. Construction has included full ligation of the thoracic aorta. The authors sought to determine if these muscle pumps could function effectively without fully ligating the aorta.

METHODS

Skeletal muscle ventricles were constructed in two groups of dogs. Group 1 had their aortas fully ligated (n = 10) while group 2 had their aortas narrowed by 50% (n = 10). The animals were followed for 10 weeks.

RESULTS

There was no significant difference in femoral diastolic augmentation at implant or at 10 weeks (19.1% +/- 9.9% in group 1 [full ligation] versus 16.3% +/- 10.2% in group 2 [half ligation] p = 0.502). Survival to 10 weeks was significantly better in group 1 (full ligation). Nine of 10 animals in this group survived versus 4 of 10 in group 2 (p = 0.019). Two animals survived in the half ligation group with effective augmentation and without thrombus formation.

CONCLUSION

Both models produce effective diastolic counterpulsation. Survival was decreased in this model using half ligation, and survival without complication was observed in 2 of 10 animals. Currently the overall results are better with the full aortic ligation model. However, design modifications will probably result in an effective model of diastolic counterpulsation without full aortic ligation.

Stable expression of human kinin B1 receptor in 293 cells: pharmacological and functional characterization

1. We compared the binding properties of [3H]-desArg10-[Leu9]-kallidin, a radiolabelled kinin B1 receptor antagonist, to membranes from IMR-90 human embryonic fibroblasts and from 293 cells transiently or stably transfected with the human B1 receptor. 2. The dissociation constant (KD) of [3H]-desArg10-[Leu9]-kallidin and the affinity of several kinin receptor agonists and antagonists were similar between the native and cloned receptor, either transiently or stably expressed in 293 cells. In IMR-90 cells, the rank order of potency was that expected for a kinin B1 receptor. 3. The receptors transiently or stably expressed in 293 cells were fully functional with respect to their signalling properties. Phosphoinositide hydrolysis was increased in a concentration-dependent manner by the B1 receptor agonist, desArg10-kallidin. Functional coupling to the calcium pathway was also demonstrated for the native and stably expressed human B1 receptor. 4. In conclusion, the established stable and functional 293 cell clone may provide an important tool for further analysis of the molecular mechanisms involved in binding, activation, and coupling of the kinin B1 receptor.

Effects of interactions between IGFBPs and IGFs on the plasma clearance and in vivo biological activities of IGFs and IGF analogs

The relative activities in vivo of IGFs that differ in their association affinities towards IGF binding proteins (IGFBPs) have been examined in a series of comparisons between IGF-I and LR3IGF-I. IGF-I has approximately 1000 fold higher affinity than LR3IGF-I towards IGFBP-3, IGFBP-4, total rat plasma IGFBPs and L6 myoblast BP. In cultured L6 myoblasts the reduced association with IGFBPs gives LR3IGF-I a 5-10 fold greater biological potency. Chronic administration of the peptides over 14 days to normal female rats produces marked increases in body weight, nitrogen retention and food conversion efficiency as well as retention of the carcass composition and fractional weights of the gut, spleen and thymus that are characteristic of the younger age. In the growth measurements LR3IGF-I is 6 fold more potent than IGF-I, thus reflecting the in vitro difference. In a second series of experiments in which the clearance rates of the two peptides were compared, LR3IGF-I was shown to be removed from the plasma much more rapidly than was IGF-I, a difference reflecting the poor association of LR3IGF-I with plasma IGFBPs. The crucial relevance of binding protein association in explaining the difference was confirmed in pregnant rats where IGFBP levels are markedly reduced. In this condition only the clearance of IGF-I was affected to produce a clearance rate almost as rapid as that found with LR3IGF-I. These experiments demonstrate that an IGF variant which associates poorly with IGFBPs is removed more rapidly from the blood and is more potent than IGF-I.