The ICDP “PaleoVan” drilling campaign at Lake Van, Turkey, provided a long (>100 m) record of lacustrine subsurface sedimentary microbial cell abundance. After the ICDP campaign at Potrok Aike, ...Argentina, this is only the second time deep lacustrine cell counts have been documented. Two sites were cored and revealed a strikingly similar cell distribution despite differences in organic matter content and microbial activity. Although shifted towards higher values, cell counts from Lake Potrok Aike, Argentina, reveal very similar distribution patterns with depth. The lacustrine cell count data are significantly different from published marine records; the most probable cause is differences in sedimentary organic matter composition with marine sediments containing a higher fraction of labile organic matter. Previous studies showed that microbial activity and abundance increase centimetres to metres around geologic interfaces. The finely laminated Lake Van sediment allowed studying this phenomenon on the microscale. We sampled at the scale of individual laminae, and in some depth intervals, we found large differences in microbial abundance between the different laminae. This small-scale heterogeneity is normally overlooked due to much larger sampling intervals that integrate over several centimetres. However, not all laminated intervals exhibit such large differences in microbial abundance, and some non-laminated horizons show large variability on the millimetre scale as well. The reasons for such contrasting observations remain elusive, but indicate that heterogeneity of microbial abundance in subsurface sediments has not been taken into account sufficiently. These findings have implications not just for microbiological studies but for geochemistry as well, as the large differences in microbial abundance clearly show that there are distinct microhabitats that deviate considerably from the surrounding layers.
Abstract Emissions of microbially produced methane (CH4) from lake sediments are a major source of this potent greenhouse gas to the atmosphere. The rates of CH4 production and emission are believed ...to be influenced by electron acceptor distributions and organic carbon contents, which in turn are affected by anthropogenic inputs of nutrients leading to eutrophication. Here, we investigate how eutrophication influences the abundance and community structure of CH4 producing Archaea and methanogenesis pathways across time–resolved sedimentary records of five Swiss lakes with well–characterized trophic histories. Despite higher CH4 concentrations which suggest higher methanogenic activity in sediments of eutrophic lakes, abundances of methanogens were highest in oligotrophic lake sediments. Moreover, while the methanogenic community composition differed significantly at the lowest taxonomic levels (OTU), depending on whether sediment layers had been deposited under oligotrophic or eutrophic conditions, it showed no clear trend in relation to in situ distributions of electron acceptors. Remarkably, even though methanogenesis from CO2-reduction was the dominant pathway in all sediments based on carbon isotope fractionation values, taxonomic identities, and genomes of resident methanogens, CO2-reduction with hydrogen (H2) was thermodynamically unfavorable based on measured reactant and product concentrations. Instead, strong correlations between genomic abundances of CO2-reducing methanogens and anaerobic bacteria with potential for extracellular electron transfer suggest that methanogenic CO2-reduction in lake sediments is largely powered by direct electron transfer from syntrophic bacteria without involvement of H2 as an electron shuttle.
International Continental Scientific Drilling Program (ICDP) drilled a complete succession of the lacustrine sediment sequence deposited during the last ~500,000 years in Lake Van, Eastern Anatolia ...(Turkey). Based on a detailed seismic site survey, two sites at a water depth of up to 360 m were drilled in summer 2010, and cores were retrieved from sub-lake-floor depths of 140 m (Northern Basin) and 220 m (Ahlat Ridge). To obtain a complete sedimentary section, the two sites were multiple-cored in order to investigate the paleoclimate history of a sensitive semi-arid region between the Black, Caspian, and Mediterranean seas. Further scientific goals of the PALEOVAN project are the reconstruction of earthquake activity, as well as the temporal, spatial, and compositional evolution of volcanism as reflected in the deposition of tephra layers. The sediments host organic matter from different sources and hence composition, which will be unravelled using biomarkers. Pathways for migration of continental and mantle-derived noble gases will be analyzed in pore waters. Preliminary 40Ar/39Ar single crystal dating of tephra layers and pollen analyses suggest that the Ahlat Ridge record encompasses more than half a million years of paleoclimate and volcanic/geodynamic history, providing the longest continental record in the entire Near East to date.
doi: 10.2204/iodp.sd.14.02.2012
As part of the International Continental Drilling Program deep lake drilling project PaleoVan, we investigated sulfate reduction (SR) in deep sediment cores of the saline, alkaline (salinity 21.4‰, ...alkalinity 155 m mEq(-1), pH 9.81) Lake Van, Turkey. The cores were retrieved in the Northern Basin (NB) and at Ahlat Ridge (AR) and reached a maximum depth of 220 m. Additionally, 65-75 cm long gravity cores were taken at both sites. SR rates (SRR) were low (≤22 nmol cm(-3) day(-1)) compared to lakes with higher salinity and alkalinity, indicating that salinity and alkalinity are not limiting SR in Lake Van. Both sites differ significantly in rates and depth distribution of SR. In NB, SRR are up to 10 times higher than at AR. SR could be detected down to 19 mblf (meters below lake floor) at NB and down to 13 mblf at AR. Although SRR were lower at AR than at NB, organic matter (OM) concentrations were higher. In contrast, dissolved OM in the pore water at AR contained more macromolecular OM and less low molecular weight OM. We thus suggest, that OM content alone cannot be used to infer microbial activity at Lake Van but that quality of OM has an important impact as well. These differences suggest that biogeochemical processes in lacustrine sediments are reacting very sensitively to small variations in geological, physical, or chemical parameters over relatively short distances.
The accurate diagnosis of "osteomyelitis" is difficult and is often delayed. However, early and radical therapy of osteomyelitis is essential. The osteomyelitis diagnosis score (ODS) was developed to ...predict the probability of osteomyelitis. The aim of our study was to validate the ODS and to investigate its practicability in daily routine.
The ODS is based on five diagnostic procedures: 1. clinical history/risk factors, 2. clinical examination/laboratory results, 3. diagnostic imaging, 4. microbiology and 5. histopathology. Each diagnostic procedure includes numerous individual findings, which are rated with 1-6 points, depending on their relevance. If the sum of the five diagnostic criteria is ≥ 17 points, the diagnosis "osteomyelitis" can be viewed as safe, between 8-17 points as probable and between 2-7 points as possible. This retrospective study included 100 patients with non-union of the tibia (2002-2010). The patients were classified into two groups: septic non-union of the tibia (experimental intervention; gold standard: positive detection of bacteria and/or positive histology) and aseptic non-union of the tibia (control intervention; no detection of bacteria and/or histology). Epidemiological data, the score's total number of points and the number of points of the score's five diagnostic procedures were analysed.
71 patients exhibited aseptic non-union of the tibia, 29 patients septic non-union. Patients with septic non-union obtained a mean of 20.8 points, and 24 at least 18 points; the diagnosis "osteomyelitis" is then presumed to be certain. Patients with aseptic non-union obtained a mean of 11.3 points, and only 3/71 patients received > 17 points. Both groups obtained the majority of points in the diagnostic procedure "clinical history". The difference between the two groups is highly significant (p < 0.001). The score's sensitivity is 82.8 %, with a specificity of 95.8 %.
The ODS was proved to be a valid score. Patients with septic non-union were identified, even if bacteria were not detected. However, the use of the ODS is demanding, as there are 104 individual findings. Many of these individual findings were negative in all patients. It would be desirable to optimise ODS, by reducing the number of queried parameters, without reduction sensitivity.
Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by ...hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material. We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i) increasing importance of fermentation in successively deeper biogeochemical zones and (ii) adaptation of H2ases to successively higher concentrations of H2 in successively deeper zones.
The disease "osteomyelitis" is characterised by different symptoms and parameters. Decisive roles in the development of the disease are played by the causative bacteria, the route of infection and ...the individual defense mechanisms of the host. The diagnosis is based on different symptoms and findings from the clinical history, clinical symptoms, laboratory results, diagnostic imaging, microbiological and histopathological analyses. While different osteomyelitis classifications have been published, there is to the best of our knowledge no score that gives information how sure the diagnosis "osteomyelitis" is in general.
For any scientific study of a disease a valid definition is essential. We have developed a special osteomyelitis diagnosis score for the reliable classification of clinical, laboratory and technical findings. The score is based on five diagnostic procedures: 1) clinical history and risk factors, 2) clinical examination and laboratory results, 3) diagnostic imaging (ultrasound, radiology, CT, MRI, nuclear medicine and hybrid methods), 4) microbiology, and 5) histopathology.
Each diagnostic procedure is related to many individual findings, which are weighted by a score system, in order to achieve a relevant value for each assessment. If the sum of the five diagnostic criteria is 18 or more points, the diagnosis of osteomyelitis can be viewed as "safe" (diagnosis class A). Between 8-17 points the diagnosis is "probable" (diagnosis class B). Less than 8 points means that the diagnosis is "possible, but unlikely" (class C diagnosis). Since each parameter can score six points at a maximum, a reliable diagnosis can only be achieved if at least 3 parameters are scored with 6 points.
The osteomyelitis diagnosis score should help to avoid the false description of a clinical presentation as "osteomyelitis". A safe diagnosis is essential for the aetiology, treatment and outcome studies of osteomyelitis.
In addition to a large number of fuhalols and phlorethols previously identified in an ethanolic extract of
Sargassum spinuligerum, a novel type of phloroglucinol derivative was isolated as its ...peracetyl derivative and identified by means of spectral analysis. In addition to a phloroglucinol unit, the new compound contains an ascorbic acid moiety. The stereochemistry of this compound was elucidated by NOE experiments in combination with molecular modelling.
International Continental Scientific Drilling Program (ICDP) drilled a complete succession of the lacustrine sediment sequence deposited during the last ~500,000 years in Lake Van, Eastern Anatolia ...(Turkey). Based on a detailed seismic site survey, two sites at a water depth of up to 360 m were drilled in summer 2010, and cores were retrieved from sub-lake-floor depths of 140 m (Northern Basin) and 220 m (Ahlat Ridge). To obtain a complete sedimentary section, the two sites were multiple-cored in order to investigate the paleoclimate history of a sensitive semi-arid region between the Black, Caspian, and Mediterranean seas. Further scientific goals of the PALEOVAN project are the reconstruction of earthquake activity, as well as the temporal, spatial, and compositional evolution of volcanism as reflected in the deposition of tephra layers. The sediments host organic matter from different sources and hence composition, which will be unravelled using biomarkers. Pathways for migration of continental and mantle-derived noble gases will be analyzed in pore waters. Preliminary 40Ar/39Ar single crystal dating of tephra layers and pollen analyses suggest that the Ahlat Ridge record encompasses more than half a million years of paleoclimate and volcanic/geodynamic history, providing the longest continental record in the entire Near East to date. doi:10.2204/iodp.sd.14.02.2012
OBJECTIVES
The purpose of this study was to assess the clinical feasibility of three-dimensional (3D) reconstruction of color Doppler signals in patients with mitral regurgitation.
BACKGROUND
...Two-dimensional (2D) color Doppler has limited value in visualizing and quantifying asymmetric mitral regurgitation. Clinical studies on 3D reconstruction of Doppler signals in original color coding have not yet been performed in patients. We have developed a new procedure for 3D reconstruction of color Doppler.
METHODS
We studied 58 patients by transesophageal 3D echocardiography. The jet area was assessed by planimetry and the jet volumes by 3D Doppler. The regurgitant fractions, the volumes, and the angiographic degree of mitral regurgitation were assessed in 28 patients with central jets and compared with those of 30 patients with eccentric jets.
RESULTS
In all patients, jet areas and jet volumes significantly correlated with the angiographic grading (r = 0.73 and r = 0.90), the regurgitant fraction (r = 0.68 and r = 0.80) and the regurgitant volume (r = 0.66 and r = 0.90). In patients with central jets, significant correlations were found between jet area and angiography (r = 0.86), regurgitant fraction (r = 0.64) and regurgitant volume (r = 0.78). No significant correlations were found between jet area and angiography (r = 0.53), regurgitant fraction (r = 0.52) and regurgitant volume (r = 0.53) in the group of patients with eccentric jets. In contrast, jet volumes significantly correlated with angiography (r = 0.90), regurgitant fraction (r = 0.75) and regurgitant volume (r = 0.88) in the group of patients with eccentric jets.
CONCLUSIONS
Three-dimensional Doppler revealed new images of the complex jet geometry. In addition, jet volumes, assessed by an automated voxel count, independent of manual planimetry or subjective estimation, showed that 3D Doppler is also capable of quantifying asymmetric jets.
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