Biomedical subjects

Bernd Markert

Publications and source records attributed to Bernd Markert.

10 recordsLinked to original sources

PubMed2006

Toxicity of heavy metals on Scenedesmus quadricauda (Turp.) de Brébisson in batch cultures.

BACKGROUND: Aquatic environments are often exposed to various pollutants like heavy metals that are released from industrial, agricultural and domestic wastes. Emissions of heavy metals can then enter all ecosystems and bring about severe problems in plants, especially algae depending on the concentrations of a given element. The objective of the investigation presented is to detect toxic effects due to some heavy metals in the biomass of green alga Scenedesmus quadricauda. METHODS: All experiments were conducted with axenic cultures of the green alga Scenedesmus quadricauda (Turp.) de Brebisson (Chlorococcales, Chlorophyta). The cultures were grown in Chu-no.10 medium, and optimum physical and chemical growth conditions were provided to get higher growth rates and lower doubling times of cells. Growth of the micro algal cultures was measured on a daily schedule by counting cultures and determination of chlorophyll-a. The sterile-filtered heavy metal concentration solutions (Cd, Pb and Cu) were prepared and added as stock solutions of their salts (CdCl2*2.5 H2O, Pb(NO3)2*H2O and CuSO4*5 H2O). RESULTS AND DISCUSSION: The growth decreased gradually with the alga exposed to Cd at 0.05, 0.1, and 0.5 mg/L in comparison with the control whereas 1 mg/L Cd2+ had a clearly destructive effect. The growth was decreased with Pb at 15, 20 and 25 mg/L gradually, while at 30 mg/L the effect was more pronounced. When Cu was used, the growth was increased gradually at 0.5, 1 and 1.5 mg/L and vice versa at 2 mg/L. CONCLUSION: There were differences in toxic effects of the metals with different metal as well as their concentrations and the time of exposure.

Biomass↗

PubMed2004

Second German heavy-metal survey by means of mosses, and comparison of the first and second approach in Germany and other European countries.

This paper shows the geographic distribution in Germany of iron (Fe), nickel (Ni) and lead (Pb) analyzed in mosses in 1995/96 and compares it with the results of the 1990/91 pilot study within a European moss-monitoring programme. Other elements (As, Cd, Cr, Cu, Ti, V, Zn) are compared on basis of the overall element medians for Germany of the 1990/91 and 1995/96 survey. Samples of Pleurozium schreberi, Scleropodium purum, Hypnum cupressiforme and Hylocomium splendens were taken at a total of 1026 sites. In the 1995/96 monitoring campaign, 95% of the original sites of the 1990/91 study were resampled. The results from 1995/96 display local elevated values and many cases of areas affected by known sources of heavy-metal emissions. The industrialized and urban regions of Germany are shown up clearly by the 1995/96 moss-monitoring results: the Ruhr area, parts of Saarland and Baden-Württemberg, as well as areas in eastern Germany. Relatively low values for many elements were found in large areas of Lower Saxony and Bavaria. A comparison of the results of the 1990/91 and 1995/96 moss-monitoring programmes shows a fall in the concentration of the presented elements (except cadmium, copper and zinc) over the relevant period. Especially in the former GDR, chromium (Cr), iron (Fe), titanium (Ti) and vanadium (V) decreased significantly. This is, firstly, a reflection of the closure of and/or technological improvements to large power plants; secondly it is due to the fact that lignite has given way to other fuels. Vanadium (V) and nickel (Ni), typical constituents of crude oil, also show a decrease in the western part and thus document changes in the type of fuel consumed. The significant fall in lead concentration in 1995/96 as compared to 1990/91 in what used to be East and West Germany probably results from the increasing use of lead-free petrol. A comparison of the median values for 1990/91 and 1995/96 in mosses to the rate of emission of heavy metals in Germany for 1990 and 1995 shows similar trends in the case of elements such as arsenic (As), chromium (Cr), nickel (Ni), and lead (Pb). The comparison of the medians of the elements analyzed for 19 European countries indicates for most of the elements a general tendency to lower values in 1995, except for Lithuania, Netherlands, Portugal, Italy and United Kingdom.

Air Pollutants↗

PubMed2003

Distribution of platinum group elements and other traffic related elements among different plants along some highways in Germany.

Using ICP-MS and ICP-AES platinum group elements (Pt, Pd, Rh, Ru and Ir) and Ce, La, Nd, Pb and Zr have been determined in street dust, Taraxacum officinale (dandelion), Plantago lanceolata (plantain), Lolium multiflorum (annual ryegrass), Rhytidiadelphus squarrosus (moss) and Vascellum pratense (mushrooms) collected along highways and streets in Germany during 1999. Among the plants Taraxacum officinale (dandelion) reflects most adequately the pollution with the investigated elements matching the results from street dust. A strong positive correlation between all elements determined in the plants is established. Transfer factor for Pt between soil and plants has been determined in an agricultural experiment ranging between 0.004 and 0.008 for two types of soils.

Agaricales↗

PubMed2003

Carcinogenesis and chemotherapy viewed from the perspective of stoichiometric network analysis (SNA): what can the biological system of the elements contribute to an understanding of tumour induction by elemental chemical noxae (e.g., Ni2+ , Cd2+ ) and to an understanding of chemotherapy?

The biological application of stoichiometric network analysis (SNA) permits an understanding of tumour induction, carcinogenesis, and chemotherapy. Starting from the Biological System of the Elements, which provides a comprehensive treatment of the functions and distributions of chemical (trace) elements in biology, an attempt is made to interrelate the essential feature of biology and--regrettably--of tumour genesis by superimposing SNA reasoning on common features of all crucial biological processes. For this purpose, aspects, effects and drawbacks of autocatalysis (identical reproduction which can occur either under control or without control [in tumours]) are linked with the known facts about element distributions in living beings and about interference of metals with tumours (in terms of both chemotherapy and carcinogenesis). The essential role of autocatalysis in biology and the drawbacks of either controlled or spontaneous cell division can be used to understand crucial aspects of carcinogenesis and chemotherapy because SNA describes and predicts effects of autocatalysis, including phase effects that may be due to some kind of intervention. The SNA-based classifications of autocatalytic networks in cell biology are outlined here to identify new approaches to chemotherapy.

Cadmium↗

PubMed2003

Toxicity of triphenyltin and tributyltin to the freshwater mudsnail Potamopyrgus antipodarum in a new sediment biotest.

The effects of two suspected endocrine-disrupting chemicals, the xeno-androgens triphenyltin (TPT) and tributyltin (TBT), were investigated in a new whole-sediment biotest with the freshwater mudsnail Potamopyrgus antipodarum (Gastropoda, Prosobranchia). Artificial sediments were spiked with seven concentrations, ranging from 10 to 500 microg nominal TPT-Sn/kg dry weight and TBT-Sn/kg dry weight, respectively. We analyzed the responses of the test species after two, four, and eight weeks exposure. For both compounds, P. antipodarum exhibited a sharp decline in the number of embryos sheltered in its brood pouch in a time- and concentration-dependent manner in comparison to the control sediment. The number of new, still unshelled embryos turned out to be the most sensitive parameter. The lowest-observed-effect concentration (LOEC) was equivalent to the lowest administered concentration (10 microg/kg of each test compound) for most parameters and thus no no-observed-effect concentration (NOEC) could be established. The calculation of effect concentrations (EC10) resulted in even lower values for both substances (EC10 after eight weeks for unshelled embryos: 0.03 microg TPT-Sn/kg, EC10 after four weeks for unshelled embryos: 0.98 microg TBT-Sn/kg). Our results indicate that P. antipodarum is highly sensitive to both endocrine disruptors TPT and TBT at environmentally relevant concentrations.

Animals↗

PubMed2002

Biogeochemical dynamics following land use change from forest to pasture in a humid tropical area (Rondĵnia, Brazil): a multi-element approach by means of XRF-spectroscopy.

Forest burning for pastures in tropical areas represents an important component of biogeochemical cycles. In order to provide information concerning chemical modifications after forest burning, in this local study the total contents of 29 elements in topsoils were analyzed when forest is changed to pasture land. The work was carried out in 1999 in Rondĵnia state (Brazilian Amazon Basin) focussing on a native forest site and four neighboring pastures established in 1987, 1983, 1972 and 1911 after forest conversion. Chemical fingerprint graphs of the pasture soils related to the forest soil illustrated mainly higher contents for the vast majority of macro- and micro nutrients, but for other elements as well (e.g. Ba, Sr, Cr, Ni, V or Pb). Also increases of pH levels were measured in all pastures, which remained higher than the forest values for decades. After initial increases of most of the elements in pasture of 1987 the decreases of some macro elements (e.g. C, N, K, Mg, S) in pasture 1983 as well as again the enhanced levels in pasture 1972 and 1911 suggest both a persistent leaching of these elements and a function of pasture age where external element inputs exceed outputs. Ash deposition, accumulation of organic matter, animal excreta as well as natural soil conditions are discussed as influencing factors on the element contents of the original forest and the pasture soils. Nevertheless, in this particular area continuous pasturing after forest clearing primarily enriched the soils in elements.

Agriculture↗

PubMed2002

Lanthanide concentrations in freshwater plants and molluscs, related to those in surface water, pore water and sediment. A case study in The Netherlands.

Industrial emissions of lanthanides to aquatic ecosystems increase, but knowledge of the environmental fate of these metals is limited. Here we focus attention upon the distribution of lanthanides in freshwater ecosystems, describing lanthanide partitioning between sediment, water and biota. Since lanthanides are often used as oxidation-state analogues for actinides, their distribution can reflect long-term behaviour of the radioactive transuranics. Concentrations of all 14 naturally occurring lanthanides were measured by ICP-MS in Sago pondweed (Potamogeton pectinatus), common duckweed (Lemna minor), seven different mollusc species (tissue and shell), two sediment fractions (< 2 mm and < 63 microm), surface water and sediment pore water from five locations in The Netherlands. In all samples, the typical 'saw-tooth' lanthanide pattern was observed, which implies that lanthanides are transported as a coherent group through aquatic ecosystems. Typical deviations from this pattern were found for Ce and Eu and could be explained by their redox chemistry. The variation in concentrations in abiotic fractions was limited, i.e. within one order of magnitude. However, variations of up to three orders of magnitude were observed in biotic samples, suggesting different affinities among organisms for lanthanides as a group, with significant differences only among molluscs and pondweed samples in relation to sampling location. For P. pectinatus it was shown that pore water was the most important lanthanide source, and for snails, food (plants) seems to be the dominant lanthanide source. Lanthanides were not equally distributed between mollusc shell and tissue and the ratio of lanthanide concentrations in shell and tissue were dependent on the sampling location. Shells contained much lower concentrations and were relatively enriched in Eu, and to a lesser extent in Ce. Bioconcentration factors for lanthanides in plants and snails relative to surface water were typically between 10000 and 100000 l x kg(-1) dry matter, while sediment-water partition coefficients were between 100000 and 3000000 l x kg(-1) dry matter. There was a low extent of biomagnification in the plant-to-snail system, with a maximum biomagnification factor of 5.5. Many distribution coefficients displayed a slight decrease with atomic number. This can be attributed to the general increase in ligand stability constants with atomic number, keeping the heavier lanthanides preferentially in solution.

Animals↗

PubMed2002

The Biological System of the Elements (BSE)--a brief introduction into historical and applied aspects with special reference on "ecotoxicological identity cards" for different element species (e.g. As and Sn).

There are different methods to estimate and predict effects of chemical elements and corresponding speciation forms in biochemistry and toxicology, including statements on essentiality and antagonisms. Two approaches are given here: (1) "identity cards" describing biologically fundamental aspects of element chemistry and (2) qualitative discussions which assume the existence of (indirect ways into) chemical autocatalysis to be essential for maintaining life and permitting reproduction. The latter method, developed by the present authors, draws upon Stoichiometric Network Analysis, a safe procedure for complexity reduction in feedback networks) and provides estimates of concentration regimes for different elements suitable for survival and reproduction. The biochemical hierarchy level considered here is that of (metallo-)proteins. Thermodynamic toxicity aspects are given in correlations with DMSO solvent affinities and thiocyanate bonding modes. Effects of antagonists and of ion substitution within metalloenzymes or of metabolic simplification can be dealt with, likewise increased sensitivities within symbiotic relationships and within carcinomas are explained which are relevant for environmental monitoring and tumour therapy, respectively.

Animals↗

PubMed2002

Transfer of selected elements from food into human milk.

OBJECTIVES: We measured the transfer factors of antimony, cerium, chromium, cobalt, gallium, lanthanum, molybdenum, niobium, ruthenium, silver, thorium, titanium, and uranium from food to milk in nursing mothers. METHODS: Food and milk samples from 19 mothers were taken daily over 2 to 8 wk. The samples were analyzed for element content after microwave-assisted pressure digestion with a mass spectrometer and inductively coupled plasma. The transfer factor, or the portion of element intake passed on in the milk, was calculated as the element concentration in food (g/kg) divided by the element concentration in milk (g/L). RESULTS: The calculated transfer factors were 5.1 for silver, 16.1 for cerium, 6.9 for chromium, 8.4 for cobalt, 19.1 for gallium, 13.8 for lanthanum, 77.4 for molybdenum, 20.7 for niobium, 4.1 for ruthenium, 13.2 for antimony, 20.2 for thorium, 5.6 for titanium, and 21.3 for uranium. Factors differed significantly across individuals. CONCLUSION: These differences can be attributed to the fact that the different levels of elements in breast milk are the result of individual differences in milk production and factors other than the amount of any particular element absorbed by the body.

Adult↗

PubMed2002

Thallium in terrestrial environments--occurrence and effects.

In this investigation thallium contents in soil and plants in the EuroRegion Neisse were analysed and the distribution determined. The median top-soil content is 0.5 mg/kg in the area investigated. In this low-contaminated area the moss Pleurozium schreberi contains 0.04-0.13 microg/g and the moss Polytrichumformosum between 0.01 and 0.05 microg/g Tl. The effects of thallium on man and the terrestrial environment were examined. In an epidemiological study a significant positive correlation was found between the thallium content of the two mosses and the incidence of diseases of the circulatory system. The LOEC for thallium in bioassays with terrestrial invertebrates and plants in artificial soil ranged from 1 to 500 mg/kg, which indicates an toxicity of thallium up to 100 times higher than that of Cadmium.

Animals↗