Biological monitoring of standardized exposure to ethylbenzene: evaluation of a biological tolerance (BAT) value

The results of standardized 8 h lasting exposures of n=18 volunteers to ethylbenzene (EthBz) at levels of 25 and 100% of the maximum allowable concentrations at the workplace (MAK) value of 100 ppm as well as the results of field studies are considered to evaluate a biological tolerance (BAT) value for EthBz. On the basis of the relationship between the external and internal exposure a BAT value of 1.5 mg/l has been set for the EthBz concentration in blood as the most sensitive and specific parameter of exposure to this aromatic hydrocarbon. The interpretation of EthBz blood values has to take into account the short half-life of t _1/2=0.5 ± 0.08 h in the first hour after the end of exposure in which this aromatic hydrocarbon is eliminated from the blood. The additional determination of the EthBz metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA), respectively, excreted in post shift urine as well as in urine samples at the beginning of the next shift shows good correlations with the external exposure. The biological half-life of MA was calculated to t _1/2=5.3 ± 1.1 h. Because the time of sampling can vary the relationship between the levels of MA to PGA the total concentration of the excreted metabolites depends less on this influence and is therefore better suited for monitoring exposed persons. On the basis of the standardized experiments a BAT value has been proposed of 2 g MA plus PGA corrected per gram creatinine. Both BAT values are adjusted to data which result from earlier standardized exposures during 30 min to EthBz under physical activity of 50 watt on a bicycle ergometer. Received: 10 August 1999 / Accepted: 2 November 1999     

Application of DNA filter hybridization and PCR to distinguish between human and non-human tissues of poor quality

Summary The present report describes a novel approach for the identification of human or non-human specimens after long-term storage in a badly preserved state. The application of the PCR-technique (polymerase chain reaction) using human-specific primers as well as Southern blot (filter) hybridization of the sample DNA to a primate-specific DNA probe enabled us to extend the positive identification beyond the limits of conventional methods such as serological or morphological examinations.     

Massenspektrometrische Untersuchungen an Edukten für die Synthese H2-aktiver Substanzen

Mess Spectrometry of Reactants for the Synthesis of H₂-Active Compounds 4-[(2-Aminoethoxy)methyl]-5-methylimidazole ( l ), the imidazoles 2-5 with N-substituted ethylenediamine structures and the imidazolecarboxamides 6–8 were investigated by electron impact mass spectrometry. The mechanisms of the competing bond fissions and of the rearrangements are explained. The neighbouring group effects of the various functional groups and their influences on the main fragmentation paths are described.     

Zur Frage der Doppelinnervation motorischer Einheiten bei der Polyneuritis

Zusammenfassung Es wird über weitere mechanographische Untersuchungen an den Hypothenarmuskeln des Menschen berichtet. An gesunden Versuchspersonen hatte sich ergeben, daß viele einzelne Fasern dieses Muskels motorisch doppelt versorgt werden (20–50%). Bei der Polyneuritis fehlt eine solche Doppelinnervation oder sie ist in ihrem Ausmaß deutlich verringert. Auf Grund der Lokalisation des Krankheitsprozesses, welcher dafür verantwortlich gemacht werden muß, sehen wir in den vorliegenden Ergebnissen eine Bestätigung unserer hypothetischen Annahme interaxonaler Anastomosen als anatomisches Substrat der beim Gesunden beobachteten Doppelinnervation der einzelnen Muskelfasern.Mit 1 TextabbildungMit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Über das Auftreten punktförmiger Blutaustritte in Totenflecken (Vibices)

Zusammenfassung Bei der statistischen Auswertung von 1023 Sektionsbefunden wurden in 76 Fällen (=7,4%) Vibices vorgefunden. Neben ihrem sporadischen Auftreten bei Lungenembolie, Pneumonie, Verbluten, Hirnschädigung und Peritonitis war eine überzufällige Häufigkeitsverteilung beim Strom- und Herztod, beim Ersticken sowie bei Vergiftungen insbesondere durch Alkohol und/oder Schlafmittel nachzuweisen. Ein einheitlicher Befund hinsichtlich der Blutstauung in den Gefäßen, des Ausprägungsgrades der Totenflecken sowie der Gefäßwand- und Herzblutbeschaffenheit konnte nicht festgestellt werden. Es wird die Vorstellung erhärtet, daß Vibices auch per diapedesin entstehen können. Als ein wesentliches Moment für ihr Auftreten wird eine starke agonochemische Kreislaufreaktion mit Ausschüttung von Catecholaminen, Histamin und Serotonin erwogen.

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Ecchymosis in death spots (Vibices)

Summary During the statistical evaluation of 1023 dissections vibices have been found in 76 cases (=7.4 p.c.). Vibices appear sporadically in connection with pulmonary embolism, pneumonia, exsanguination, brain damage and peritonitis. They were especially and significantly frequent in cases of death caused by electrocution or heartfailure, by suffocation and poisoning especially through alcohol and/or hypnotics. As far as hyperaemia in vessels, the intensity of death spots, the quality of vascular well and of cardiac blood are concerned, the examination did not produce unified results. Examinations strenghten the assumption that vibices also occur per diapedesin. It is assumed that their appearance is essentially caused by agono-chemical circulation reactions in connection with an increased outpour of catecholamines, histamin and serotonin.

     

Ringschlußreaktionen mit N-(Chlormethyl)carbimidoylchloriden, 2. Mitt. Umsetzungsprodukte mit N,N′-Dimethylthioharnstoff

Heterocyclisation Reactions with N-(Chloromethyl)carboximidoyl Chlorides, II: Reaction with N, N′-Dimethylthiourea N-(Chloromethyl)benzimidoyl chloride ( 1 ) and N, N′-dimethylthiourea ( 2 ) react to form the three isomeric triazine and thiadiazine derivatives 6 , 7 and 8 , which were separated by layer chromatography. Their structures were determined by ¹³C-NMR spectroscopy. The thiadiazine derivative 11 was isolated as a by-product. A mechanism is proposed for its formation.     

A proposal for the repositioning of prophylactic breast radiotherapy of prostate cancer patients

Patients with prostate cancer treated with small-molecular, nonsteroidal anti-androgens frequently develop mammalgia and gynecomastia. To avoid these unwanted effects, pretherapeutic radiation therapy of the male breasts is in common use. Recent findings on the effectivity of prevention and treatment of breast pain and gynecomastia, by both radiation therapy and tamoxifen, and a new comparative study, necessitate a re-evaluation of current prophylactic and therapeutic treatment options. An evidence-based treatment algorithm is derived that diverges from previous recommendations and redefines the role of preventive and therapeutic radiation therapy. For the propylaxis of gynecomastia and breast pain, tamoxifen is superior to single-dose radiation therapy with 10 Gy. Hence, if tamoxifen for this indication should prove to be safe on longer follow-up, radiation therapy would only be indicated in situations where tamoxifen therapy is impossible or contraindicated. The same is proposed for the treatment of early gynecomastia or breast pain except with tamoxifen treatment failure as an additional indication. Higher radiation doses of 4 x 5 Gy, which were shown to be effective in this setting, have not yet been evaluated against anti-estrogen therapy.     

A bronchogenic cyst of the right ventricular endocardium

In a 73-year-old male patient with a history of prostate cancer, a right ventricular endoluminal tumor was diagnosed by echocardiography. An endocardial papillary fibroelastoma or myxoma appeared possible; a malignant tumor could not be ruled out. The tumor was resected using extracorporeal circulation and cardioplegic arrest. Histopathology study revealed a bronchogenic cyst with ciliated epithelium.     

The modifying effects of stimulation pattern and propofol plasma concentration on motor-evoked potentials

The quality of intraoperative motor-evoked potentials (MEPs) largely depends on the stimulation pattern and anesthetic technique. Further improvement in intraoperative MEP recording requires exact knowledge of the modifying effects of each of these factors. Accordingly, we designed this study to characterize the modifying effect of different stimulation patterns during different propofol target plasma concentrations (PTPCs) on intraoperatively recorded transcranial electrical MEPs. In 12 patients undergoing craniotomy, stimulation patterns (300-500 V; 100-1000 Hz; 1-5 stimuli) were varied randomly at different PTPCs (2, 4, and 6 microg/mL). Remifentanil was administered unchanged at 0.2 microg . kg(-1) . min(-1). MEPs were recorded from the thenar and hypothenar muscles. Analysis of MEPs was blinded to the PTPC. Three-way analysis of variance revealed significant main effects of increasing stimulation intensity, frequency, and number of stimuli on MEP amplitude (P < 0.05). Maximum MEP amplitudes and recording success rates were observed with three or more stimuli delivered at 1000 Hz and > or =150 V. A significant main effect of PTPC (2 vs 4 and 6 microg/mL) on MEP amplitude was observed at the thenar recording site only (P < 0.05). An amplitude ratio calculated from corresponding MEPs evoked by double and quadruple stimulation proved to be insensitive to changes in PTPC. In conclusion, MEP characteristics varied significantly in response to changes in stimulation pattern and less to changes in PTPC.