Anthropogenic- and natural sources of dust in peatland during the Anthropocene

As human impact have been increasing strongly over the last decades, it is crucial to distinguish human-induced dust sources from natural ones in order to define the boundary of a newly proposed epoch - the Anthropocene. Here, we track anthropogenic signatures and natural geochemical anomalies in the Mukhrino peatland, Western Siberia. Human activity was recorded there from cal AD 1958 (±6). Anthropogenic spheroidal aluminosilicates clearly identify the beginning of industrial development and are proposed as a new indicator of the Anthropocene. In cal AD 1963 (±5), greatly elevated dust deposition and an increase in REE serve to show that the geochemistry of elements in the peat can be evidence of nuclear weapon testing; such constituted an enormous force blowing soil dust into the atmosphere. Among the natural dust sources, minor signals of dryness and of the Tunguska cosmic body (TCB) impact were noted. The TCB impact was indirectly confirmed by an unusual occurrence of mullite in the peat.

Glasshouse vs field experiments: do they yield ecologically similar results for assessing N impacts on peat mosses?

• Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating multifactorial experiments. • We investigated whether glasshouse experiments are reliable proxies for field experiments for assessing interactions between N deposition and environment as controls on Sphagnum N concentration and production. We performed a meta-analysis over 115 glasshouse experiments and 107 field experiments. • We found that glasshouse and field experiments gave similar qualitative and quantitative estimates of changes in Sphagnum N concentration in response to N application. However, glasshouse-based estimates of changes in production--even qualitative assessments-- diverged from field experiments owing to a stronger N effect on production response in absence of vascular plants in the glasshouse, and a weaker N effect on production response in presence of vascular plants compared to field experiments. • Thus, although we need glasshouse experiments to study how interacting environmental factors affect the response of Sphagnum to increased N deposition, we need field experiments to properly quantify these effects.

Climatic modifiers of the response to nitrogen deposition in peat-forming Sphagnum mosses: a meta-analysis

Peatlands in the northern hemisphere have accumulated more atmospheric carbon (C) during the Holocene than any other terrestrial ecosystem, making peatlands long-term C sinks of global importance. Projected increases in nitrogen (N) deposition and temperature make future accumulation rates uncertain. Here, we assessed the impact of N deposition on peatland C sequestration potential by investigating the effects of experimental N addition on Sphagnum moss. We employed meta-regressions to the results of 107 field experiments, accounting for sampling dependence in the data. We found that high N loading (comprising N application rate, experiment duration, background N deposition) depressed Sphagnum production relative to untreated controls. The interactive effects of presence of competitive vascular plants and high tissue N concentrations indicated intensified biotic interactions and altered nutrient stochiometry as mechanisms underlying the detrimental N effects. Importantly, a higher summer temperature (mean for July) and increased annual precipitation intensified the negative effects of N. The temperature effect was comparable to an experimental application of almost 4 g N m(-2)  yr(-1) for each 1°C increase. Our results indicate that current rates of N deposition in a warmer environment will strongly inhibit C sequestration by Sphagnum-dominated vegetation.

Prevention of brain metastasis formation by local expression of interleukin-4 or hemagglutinin antigen

INTRODUCTION

Expression of hemagglutinin antigen of influenza virus (HA) by the murine colon carcinoma cell line (CT-26) produces systemic immunization against tumor challenges in the cecum, liver and lungs but not in the brain of BALB/c-mice. Immunization with IL-4 expressing CT-26 cells inhibits lung metastases formation. The purpose of our study was to examine the effects of HA or IL-4 expression on brain metastases formation.

METHODS

Using selective internal carotid artery injections, brain metastases formation of HA or IL-4 expressing CT-26 cells with and without subcutaneous pre-immunization was evaluated in Balb/c mice.

RESULTS

Systemic pre-immunization with HA or IL-4 expressing tumor cells cannot protect against brain metastases, while the local, intracerebral expression of HA or IL-4 inhibits the growth of hematogenous brain metastases.

CONCLUSION

Pre-immunization with HA or IL-4 expressing tumor cells did produce systemic immunity against liver and lung metastases but not against brain metastases. Local, intracerebral expression of HA or IL-4 prevents from cerebral metastases formation in an animal model.

Structure of microbial communities in Sphagnum peatlands and effect of atmospheric carbon dioxide enrichment

Little is known about the structure of microbial communities in Sphagnum peatlands, and the potential effects of the increasing atmospheric CO2 concentration on these communities are not known. We analyzed the structure of microbial communities in five Sphagnum-dominated peatlands across Europe and their response to CO2 enrichment using miniFACE systems. After three growing seasons, Sphagnum samples were analyzed for heterotrophic bacteria, cyanobacteria, microalgae, heterotrophic flagellates, ciliates, testate amoebae, fungi, nematodes, and rotifers. Heterotrophic organisms dominated the microbial communities and together represented 78% to 97% of the total microbial biomass. Testate amoebae dominated the protozoan biomass. A canonical correspondence analysis revealed a significant correlation between the microbial community data and four environmental variables (Na+, DOC, water table depth, and DIN), reflecting continentality, hydrology, and nitrogen deposition gradients. Carbon dioxide enrichment modified the structure of microbial communities, but total microbial biomass was unaffected. The biomass of heterotrophic bacteria increased by 48%, and the biomass of testate amoebae decreased by 13%. These results contrast with the absence of overall effect on methane production or on the vegetation, but are in line with an increased below-ground vascular plant biomass at the same sites. We interpret the increase in bacterial biomass as a response to a CO2-induced enhancement of Sphagnum exudation. The causes for the decrease of testate amoebae are unclear but could indicate a top-down rather than a bottom-up control on their density.

[Preoperative MR mammography in breast carcinoma. Effect on operative treatment from the surgical viewpoint]

INTRODUCTION

In a prospective study the diagnostic validity of magnetic resonance mammography (MRM) as well as its impact on the choice of the operative procedure in the treatment of breast cancer was examined. In 125 patients who were suspected of having breast cancer by clinical examination, ultrasound, and X-ray mammography, additional bilateral MRM was performed. Of special interest was the diagnostic potential of MRM with regard to multifocal, multicentric and contralateral lesions.

METHODS

After a complete resection all lesions diagnosed by the various conventional methods were examined patho-histologically. In 112 patients, complete data were available to calculate the sensitivity and the specificity of each method as well as to correlate its results with the pathohistological findings.

RESULTS

In 91 cases, a breast carcinoma was diagnosed by conventional methods, with a sensitivity/specificity of 73%/67% for clinical examination, of 58%/86% for ultrasound, and of 89%/20% for X-ray mammography. In this preselected series of patients with a prevalence of 81.25% the diagnosis established by the various methods was confirmed by MRM with sensitivity of 96.7% and specificity of 19%. Forty-six additional suspicious lesions were found only by MRM, of which 28 were malignant (25 multifocal or multicentric and 3 contralateral carcinomas), and 18 benign. The rate of false-positive MRM results was 18%. Due to the MRM findings, the therapeutic procedure was changed from breast preservation to mastectomy in 14.3%.

CONCLUSION

Not only for the differential diagnosis of discrepant findings between X-ray mammography and ultrasound, but especially for the diagnosis of multifocal or multicentric lesions, MRM seems to be the method of choice. Consequently, MRM plays an important role in planning the operative procedure in breast cancer patients, especially in the context of breast preservation. To ensure optimal use of this new diagnostic tool high technical standards, proper expertise on the part of the examining radiologist, and effective cooperation among the involved disciplines (radiology, pathology, surgery) must be guaranteed.

Expression and functional significance of vascular endothelial growth factor receptors in human tumor cells

Vascular endothelial growth factor (VEGF) is one of the key factors in tumor neoangiogenesis, acting through its receptors KDR (VEGFR-2) and fit-1 (VEGFR-1) expressed on endothelial cells. Our data demonstrate that VEGFR-1 and to a lesser extent VEGFR-2 are expressed in a number of human tumor tissues and derived cells in culture. VEGFR-1 protein is expressed in 26 of 42 glioma tissues, 22 of which show a coexpression of VEGFR-1 with VEGFR-2; 1 glioma tissue expresses exclusively VEGFR-2. In the derived glioma cell cultures, we found VEGFR-1 mRNA expression in 6 of 11 cultures, with one coexpressing VEGFR-1 and VEGFR-2. Of four established glioma cell lines, two expressed VEGFR-1. In addition VEGFR-1 protein expression was demonstrated in 30 of 37 tumor tissues of squamous cell carcinomas of the head and neck, with VEGFR-2 coexpression in 15 tissues and an expression of VEGFR-2 alone in 1 tissue. Derived tumor cell cultures showed mRNA expression of VEGFR-1 alone in seven of seven cases. Established melanoma cell lines expressed VEGFR-1 mRNA in four of five lines, with VEGFR-2 coexpression in two lines. Concerning the functional significance of VEGF receptor expression, VEGF treatment of VEGFR-1-expressing tumor cells induced the inhibition of cell proliferation by 25 to 55% and the inhibition of tumor cell migration by 29 to 55%. Thus our data indicate that the coexpression of VEGF and VEGFR-1 in tumor cells could have an inhibitory effect on tumor cell proliferation and migration, a mechanism possibly induced as a response to a deficiency in nutrient and oxygen supply.

[Effect of MR mammography on surgical procedure in operative treatment of breast cancer]

In addition to conventional imaging techniques, magnetic resonance (MR) mammography is an important tool in the diagnosis of breast cancer. It has proved to be the method of choice especially for the differential diagnosis of discrepant findings between mammography and ultrasound as well as the detection of multifocal and multicentric disease. In this context MR mammography is a meaningful method for the planning of breast preserving surgery and seems likely to become routine practice as long as the preconditions for high quality performance are guaranteed.

A new sampler for extracting undisturbed surface peat cores for growth pot experiments

The sampler extracts uncompressed cores of 13·3 cm in diameter, up to 70 cm long, from the surface layers of peat. It has two close-fitting concentric cylindrical tubes, the outer one acting as a cutter and the inner one as a collector. As the outer tube is introduced by rotation into the peat, the cut core is collected in the inner tube which is maintained in a fixed position during the rotation phase and then pushed down stepwise. This limits friction between the peat core and the wall of the corer and prevents compression or distortion of the peat. These problems are also reduced by means of three skew cutters allowing the peat to be supported during the slicing action. Air can penetrate between the tubes to the lower end of the core, suppressing any suction effect during withdrawal. The sampler has been tested and has worked satisfactorily in many different peat types.