Iron (Fe) speciation in size-fractionated aerosol particles in the Pacific Ocean: The role of organic complexation of Fe with humic-like substances in controlling Fe solubility

Atmospheric deposition is one of the main sources of dissolved iron (Fe) in the ocean surfaces. Atmospheric processes are recognized as controlling fractional Fe solubility (Fesol%) in marine aerosol particles. However, the impact of these processes on Fesol% remains unclear. One of the reasons for this is the lack of field observations focusing on the relationship between Fesol% and Fe species in marine aerosol particles. In particular, the effects of organic ligands on Fesol% have not been thoroughly investigated in observational studies. In this study, Fe species in size-fractionated aerosol particles in the Pacific Ocean were determined using X-ray absorption fine structure (XAFS) spectroscopy. The internal mixing states of Fe and organic carbon were investigated using scanning transmission X-ray microscopy (STXM). The effects of atmospheric processes on Fesol% in marine aerosol particles were investigated based on the speciation results. Iron in size-fractionated aerosol particles was mainly derived from mineral dust, regardless of aerosol diameter, because the enrichment factor of Fe was almost 1 in both coarse (PM&gt;1.3) and fine aerosol particles (PM1.3). Approximately 80 % of the total Fe (insoluble + labile Fe) was present in PM&gt;1.3, whereas labile Fe was mainly present in PM1.3. The Fesol% in PM&gt;1.3 was not significantly increased (2.56±2.53 %, 0.00 %–8.50 %, n=20) by the atmospheric processes because mineral dust was not acidified beyond the buffer capacity of calcite. In contrast, mineral dust in PM1.3 was acidified beyond the buffer capacity of calcite. As a result, Fesol% in PM1.3 (0.202 %–64.7 %, n=10) was an order of magnitude higher than that in PM&gt;1.3. The PM1.3 contained ferric organic complexes with humic-like substances (Fe(III)-HULIS, but not Fe-oxalate complexes), and the abundance correlated with Fesol%. Iron(III)-HULIS was formed during transport in the Pacific Ocean because Fe(III)-HULIS was not found in aerosol particles in Beijing and Japan. The pH estimations of mineral dust in PM1.3 established that Fe was solubilized by proton-promoted dissolution under highly acidic conditions (pH &lt; 3.0), whereas Fe(III)-HULIS was stabilized under moderately acidic conditions (pH 3.0–6.0). Since the observed labile Fe concentration could not be reproduced by proton-promoted dissolution under moderately acidic conditions, the pH of mineral dust increased after proton-promoted dissolution. The cloud process in the marine atmosphere increases the mineral dust pH because the dust particles are covered with organic carbon and Na. The precipitation of ferrihydrite was suppressed by Fe(III)-HULIS owing to its high water solubility. Thus, the organic complexation of Fe with HULIS plays a significant role in the stabilization of Fe that was initially solubilized by proton-promoted dissolution.</p

Dobutamine stress echocardiography for assessing the role of dynamic intraventricular obstruction in left ventricular ballooning syndrome

<p>Abstract</p> <p>Background</p> <p>Dynamic intraventricular obstruction has been observed in patients with left ventricular ballooning syndrome (LVBS) and has been hypothesized as a possible mechanism of the syndrome. The aim of this study was to assess the prevalence and significance of dynamic intraventricular obstruction in patients with LVBS.</p> <p>Methods and Results</p> <p>Dobutamine stress echocardiography was carried out in 22 patients with LVBS (82% apical), all women, aged 68 ± 9 years. At baseline 1 patient had a > 30 mmHg LV gradient; during stress a LV gradient > 30 mm Hg developed in 6/21 patients (28%) and was caused by systolic anterior motion of the mitral valve in the 3 patients with severe gradient (mean 116 ± 29 mmHg), who developed mitral regurgitation and impaired apical wall motion and by obstruction at mid-ventricular level in the other 3 with a moderate gradient (mean 46 ± 16 mmHg). Compared with patients without obstruction those with obstruction had a greater mean septal thickness (11.6 ± .6 vs 9.8. ± 3, p < .01), a higher prevalence of septal hypertrophy (71% vs 7%, p < .005) and a higher peak wall motion score index (1.62 ± .4 vs 1.08 ± .4, p < .01).</p> <p>Conclusion</p> <p>Spontaneous or dobutamine-induced dynamic LV obstruction is documented in 32% of patients with LVBS, is correlated with the presence of septal hypertrophy and may play a role in the development of LVBS in this subset of patients. In those without septal hypertrophy a dynamic obstruction is rarely induced with dobutamine and is unlikely to be a major pathogenetic factor of the syndrome.</p

Lectin-like bacteriocins from pseudomonas spp. utilise D-rhamnose containing lipopolysaccharide as a cellular receptor

Lectin-like bacteriocins consist of tandem monocot mannose-binding domains and display a genus-specific killing activity. Here we show that pyocin L1, a novel member of this family from Pseudomonas aeruginosa, targets susceptible strains of this species through recognition of the common polysaccharide antigen (CPA) of P. aeruginosa lipopolysaccharide that is predominantly a homopolymer of d-rhamnose. Structural and biophysical analyses show that recognition of CPA occurs through the C-terminal carbohydrate-binding domain of pyocin L1 and that this interaction is a prerequisite for bactericidal activity. Further to this, we show that the previously described lectin-like bacteriocin putidacin L1 shows a similar carbohydrate-binding specificity, indicating that oligosaccharides containing d-rhamnose and not d-mannose, as was previously thought, are the physiologically relevant ligands for this group of bacteriocins. The widespread inclusion of d-rhamnose in the lipopolysaccharide of members of the genus Pseudomonas explains the unusual genus-specific activity of the lectin-like bacteriocins

Takotsubo cardiomyopathy after a dancing session: a case report

<p>Abstract</p> <p>Introduction</p> <p>Stress-induced (Takotsubo) cardiomyopathy is a rare form of cardiomyopathy which presents in a manner similar to that of acute coronary syndrome. This sometimes leads to unnecessary thrombolysis therapy. The pathogenesis of this disease is still poorly understood. We believe that reporting all cases of Takotsubo cardiomyopathy will contribute to a better understanding of this disease. Here, we report a patient who, in the absence of any recent stressful events in her life, developed the disease after a session of dancing.</p> <p>Case presentation</p> <p>A 69-year-old Caucasian woman presented with features suggestive of acute coronary syndrome shortly after a session of dancing. Echocardiography and a coronary angiogram showed typical features of Takotsubo cardiomyopathy and our patient was treated accordingly. Eight weeks later, her condition resolved completely and the results of echocardiography were totally normal.</p> <p>Conclusions</p> <p>Takotsubo cardiomyopathy, though transient, is a rare and serious condition. Although it is commonly precipitated by stressful life events, these are not necessarily present. Our patient was enjoying one of her hobbies (that is, dancing) when she developed the disease. This case has particular interest in medicine, especially for the specialties of cardiology and emergency medicine. We hope that it will add more information to the literature about this rare condition.</p

An incremental approach to automated protein localisation

Tscherepanow M, Jensen N, Kummert F. An incremental approach to automated protein localisation. BMC Bioinformatics. 2008;9(1): 445.Background: The subcellular localisation of proteins in intact living cells is an important means for gaining information about protein functions. Even dynamic processes can be captured, which can barely be predicted based on amino acid sequences. Besides increasing our knowledge about intracellular processes, this information facilitates the development of innovative therapies and new diagnostic methods. In order to perform such a localisation, the proteins under analysis are usually fused with a fluorescent protein. So, they can be observed by means of a fluorescence microscope and analysed. In recent years, several automated methods have been proposed for performing such analyses. Here, two different types of approaches can be distinguished: techniques which enable the recognition of a fixed set of protein locations and methods that identify new ones. To our knowledge, a combination of both approaches – i.e. a technique, which enables supervised learning using a known set of protein locations and is able to identify and incorporate new protein locations afterwards – has not been presented yet. Furthermore, associated problems, e.g. the recognition of cells to be analysed, have usually been neglected. Results: We introduce a novel approach to automated protein localisation in living cells. In contrast to well-known techniques, the protein localisation technique presented in this article aims at combining the two types of approaches described above: After an automatic identification of unknown protein locations, a potential user is enabled to incorporate them into the pre-trained system. An incremental neural network allows the classification of a fixed set of protein location as well as the detection, clustering and incorporation of additional patterns that occur during an experiment. Here, the proposed technique achieves promising results with respect to both tasks. In addition, the protein localisation procedure has been adapted to an existing cell recognition approach. Therefore, it is especially well-suited for high-throughput investigations where user interactions have to be avoided. Conclusion: We have shown that several aspects required for developing an automatic protein localisation technique – namely the recognition of cells, the classification of protein distribution patterns into a set of learnt protein locations, and the detection and learning of new locations – can be combined successfully. So, the proposed method constitutes a crucial step to render image-based protein localisation techniques amenable to large-scale experiments