Review of the Ecotoxicological Properties of the Methylenedianiline Substances.

Concerning chronic toxicity, D. magna is the most sensitive species tested against MDA aquatic exposures, with a 21 days-NOEC of 0.00525 mg/L. Exposure of daphnids takes place via the aquatic phase. Other species of the same phylum (Arthropoda) appear to be less sensitive albeit with exposures via soil or sediment, with a 28 days-NOEC of 562 mg/kg d. w. soil (F. candida) and 41.3 mg/kg d. w. sediment (Hyalella azteca), for reproductive and survival endpoints, respectively. Also for acute toxicity, D. magna is more sensitive than the other species, with an 48 h-EC50 that spreads over two orders of magnitude, ranging from 0.019 to 2.7 mg/L. Fish show a more uniform reaction to MDA, with 96 h-LC50 ranging from about 20 to 60 mg/L; chronic data for fish are not available. Acute toxicity data for algae and cyanobacteria are in the range of 1-10 mg/L; based on growth rate, the 72 h-NOECr or ErC10 of MDA to algae is 0.3-9.3 mg/L.For sediment organisms, the black worm L. variegatus shows the highest sensitivity against MDA with a NOEC between ≤3.75 mg/kg and 30 mg/kg d. w., followed by the amphipod H. azteca. The lower sensitivity of L. variegatus in the second study compared to the first study is obviously attributable to the different feeding regimes (semi-continuous feeding against pre-spiked sediment). One argument might be that semi-continuous feeding allows the organisms to avoid the contaminated food. However, a change from semi-continuous feeding to sediment pre-spiked with nettle powder (Urtica sp.) results in an earlier and much stronger increase in ammonia concentration in the system. This became apparent after both studies on the blackworm were finalized. The ammonia 96 h-EC50 for the blackworm is 0.69 mg/L at pH = 8.2, and the 96 h-EC10 at pH = 8.2 is 0.33 mg/L (Hickey and Vickers, Arch Environ Contam Toxicol 26:292-298, 1994). As a result, the lower NOEC and LOEC in the second study with L. variegatus are probably attributable to interference by ammonia.MDA binds irreversibly to soil and sediment which may explain the general, but not uniform lower sensitivity of soil and sediment organisms against aquatic organisms. However, species with intense soil or sediment contact (L. variegatus and E. fetida) show in general lower NOEC values than those organisms with less direct contact (3.75 and 11.2 mg/kg d. w., respectively). On the one hand it may be hypothesized that this intense contact to soil bound MDA is one reason for the higher sensitivity; on the other hand, metabolic capacity against MDA of the organisms tested is unknown at this point in time and might as well explain differences in species sensitivity. For plants there are only acute data available, and in respect to acute toxicity L. sativa is more sensitive to MDA than E. fetida.Limited aquatic data available so far do not indicate that the toxicity of pMDA is different to MDA. In addition, the limited set of data generated with the marine M. macrocopa (crustacean), N. fustulum (diatom) and V. fisheri (bacteria) do not indicate that sea water organisms are more sensitive to MDA than fresh water organisms.In mammals, MDA is unlikely to interact with the endocrine sexual system; interaction with the adrenergic system cannot be ruled out, and effects of MDA on the thyroid hormone system have been demonstrated. MDA inhibits the thyroid peroxidase which might contribute to the thyroid gland tumors observed in chronic studies with rats and mice. Some anti-androgenic activity in in vitro studies with yeast cell did not prevail in in vivo studies with rats and mice.

[Telemonitoring of implantable devices. Practical aspects and ongoing studies]. / Telemonitoring implantierbarer Aggregate. Praktische Aspekte und laufende Studien.

Telemedicine is used in various areas of cardiology, e.g., for the detection of cardiac arrhythmias and monitoring coronary artery disease and heart failure. Telemedicine is playing an increasing role is the monitoring of implantable devices (pacemakers, defibrillators, and event recorders). Most manufacturers of these devices have, in the meantime, telemedical concepts. The current guidelines of cardiac societies advocate the implantation of telemedicine-controlled devices. In the practical implementation of telemedicine devices, recruitment and involvement of patients, setting up of telemedicine consultation, legal aspects, and financing questions are of special relevance.

Interlaboratory trial on the analysis of alkylphenols, alkylphenol ethoxylates, and bisphenol A in water samples according to ISO/CD 18857-2.

ISO/CD 18857-2 (International Organization for Standardization, Geneva) describes a new international standard method for the determination of octylphenol, nonylphenol, their mono- and diethyoxylates, and bisphenol A in nonfiltered samples of drinking, ground, surface, and wastewater. The method is based on the extraction of the analytes from an acidified water sample by solid phase extraction, solvent elution, derivatization, and determination by gas chromatography with mass spectrometric detection. For validation of this method, 14 laboratories from 4 different countries in Europe and Canada participated in an interlaboratory trial to determine the performance characteristics of the method, which are intended for publication in the corresponding standard. The interlaboratory trial was evaluated according to ISO 5725-2 and included two duplicate nonfiltered water samples: surface water containing the target compounds in an analyte concentration range from 0.05 to 0.4 microg/L and wastewater containing the target compounds in a concentration ranged from 0.1 to 5 microg/L. The repeatability variation coefficients (within-laboratory precision) varied for all samples and compounds between 1.9 and 7.8%, showing a sufficiently high repeatability of the method. The reproducibility variation coefficients (between-laboratory precision) were found to vary within a satisfactory range of 10.0-29.5% for surface water and 10.8-22.5% for wastewater. The recoveries as a measure of accuracy varied from 98.0 to 144.1% for surface water and from 95.4 to 108.6% for wastewater. The determined concentrations of the samples compared well to the "true" values, thus showing very satisfactory accuracy of the method. In the chromatogram of the surface water sample, a high unresolved background made up of coextractable matrix compounds was apparent. It is conceivable that compounds from this background may be responsible for enhanced recoveries of 144.1% for 4-nonylphenol (mixture of isomers) and of 123.4% for 4-nonylphenol monoethoxylate (mixture of isomers) in the surface water samples. The isotope-marked standard compounds developed in this context proved to be reliable internal standards that allow a precise and accurate quantitation of all compounds specified in ISO/CD 18857-2. The results of the interlaboratory trial confirmed that the analytical method is robust and reliable and can be used as a standard method to analyze the target compounds in water samples.

[Clinical aspects of image quality and doses in gated pulsed imaging]. / Klinische Aspekte zu Bildqualität und Dosis bei gittergesteuerter gepulster Durchleuchtung.

PURPOSE: The relations between image quality in last image hold images and dose in grid controlled fluoroscopy in comparison to the continuous mode need to be characterised and recommendations for the clinical application of this technique should be given. MATERIAL AND METHODS: Spatial resolution, signal-noise ratio and, contrast-detail visibility were evaluated by phantom measurements in grid controlled pulsed and continuous fluoroscopy. Dose was measured at the image intensifier entrance. Image quality of last image hold (LIH) images of clinical examinations was graded in relation to single shot exposures. RESULTS: Signal-noise ratio and contrast-detail visibility depend on the dose per puls. Spatial resolution and contrast-detail visibility in grid controlled fluoroscopy are superior than to in the continuous mode. Image quality of the LIH images from the grid controlled fluoroscopy was improved. Radiation exposure could be reduced to 10-46%. CONCLUSIONS: Combinations of puls-dose and -frequency are recommended for achieving extensive dose reduction and improved image quality of LIH images.

[Initial experiences with pulsed fluoroscopy on a multifunctional fluoroscopic unit]. / Erste Erfahrungen mit gepulster Durchleuchtung an einer multifunktionellen Durchleuchtungsanlage.

PURPOSE: Comparison of radiation doses in pulsed and continuous fluoroscopy to quantify the dose reduction by pulsed fluoroscopy. Further, the applicability of pulsed fluoroscopy in clinical routine has been evaluated. MATERIALS AND METHODS: In a human pelvic phantom, the radiation dose (skin entry dose in cGycm2) was measured at two pulses per second (pps), 3 pps, 6 pps, 12 pps and continuous fluoroscopy mode, respectively, using image-intensifier entries of 38 cm, 25 cm, and 17 cm. 300 examinations were carried out, and the results of the different fluoroscopy modes were registered. RESULTS: Dose reduction depends on the image-intensifier entry. Compared to the radiation dose in continuous fluoroscopy, with 12 pps fluoroscopy the radiation dose can be reduced at a minimum of 51%, with 6 pps fluoroscopy to 40%, with 3 pps fluoroscopy to 20%, and with 2 pps fluoroscopy to a minimum of 14.5%. Clinical routine has shown that 78% of all examinations can be performed with 2 or 3 pps fluoroscopy mode. In 12.7% of the cases pulsed fluoroscopy of diverse frequencies was used, in an additional 2% combined with continuous fluoroscopy. Exclusively, continuous fluoroscopy has been employed in 2% of the cases. CONCLUSIONS: Using pulsed fluoroscopy, an 80% reduction of the radiation dose compared to continuous fluoroscopy is possible. About 96% of all examinations can be performed with pulsed fluoroscopy of different pulse rate and without using continuous fluoroscopy.

Resolution of stereoisomers of dipeptides by gas chromatography on Chirasil-Val.

Several dipeptides have been separated into stereoisomers (enantiomers, diastereomers, sequential isomers) by gas chromatography on Chirasil-Val. Sufficiently volatile N-trifluoroacetyl dipeptide methyl esters were formed at ambient temperature, thus avoiding racemization (or epimerization, respectively, and cleavage of the peptide bond. This method is suitable for ascertaining the stereoisomeric composition of dipeptides in biological samples.