Publications by authors named "M Klees"

Article Synopsis
  • A study was conducted to evaluate the effectiveness of macitentan, an endothelin-1 receptor inhibitor, in treating patients with angina caused by coronary artery spasm (CAS) who continued to experience symptoms despite standard treatment.
  • 28 participants (mainly women, average age 55) were given either macitentan or a placebo for four weeks, followed by a switch, measuring changes in anginal burden during each phase.
  • Results showed no significant difference in anginal burden between macitentan and placebo, and the frequency and severity of side effects were similar for both treatments.
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During this study the occurrence of polychlorinated biphenyls (PCBs) in the surrounding of an e-waste recycling facility in North-Rhine Westphalia was analysed. PCB levels were analysed in curly kale, spruce needles, street dusts and dusts. Conspicuously high PCB concentrations in curly kale and spruce needles were found directly northwards of the industrial premises.

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During this study a high throughout selective pressurized liquid extraction (SPLE) method was developed and validated for the simultaneous extraction of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/PCDFs) and polychlorinated biphenyls (PCBs) from soil. To that end, extraction rates of PCBs from soil utilizing different extraction solvents and different extraction temperatures were investigated whereas extraction rates were comparable for toluene, n-hexane and dichloromethane (extraction conditions for all utilized solvents: 33mL PLE extraction cell, extraction temperature: 110°C, static extraction time: 5min, flush volume: 60%, purge 90s). Ratios of native PCBs and PCDD/PCDFs congener concentrations after Soxhlet and selective pressurized liquid extraction (SPLE) showed that SPLE is an alternative sample preparation step for the simultaneous determination of PCDD/PCDFs and PCBs in soil.

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During this study wipe sampling was applied to various impervious surfaces for the determination of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs) area concentrations. To that end, a wipe sampling method based on solvent wetted cotton wipes was evaluated and transfer efficiencies of PCBs and PCDD/PCDFs in particulate films (PFs) and oily liquid films (OFs) during sampling were investigated. For PFs sufficient transfer efficiencies of low concentrated PCB and PCDD/PCDF congeners in 1g/m(2) spiking surrogate were achieved after the first wipe using n-hexane as wetting solvent.

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In this study the occurrence of polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/PCDFs) in street dust samples was investigated using pressurized liquid extraction and gas chromatography coupled to mass spectrometry. Street dust samples were taken from rural, urban, industrial and industrially influenced urban areas. PCB6 concentrations ranged from 5090±2200 μg/kg (average±standard error of mean) in dusts from industrial premises to 29±8.

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