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Featured researches published by Thomas Keller.


Journal of Insect Science | 2006

Juvenile Hormone Titer Versus Juvenile Hormone Synthesis in Female Nymphs and Adults of the German Cockroach, Blattella germanica

Karl Treiblmayr; Nuria Pascual; Maria-Dolors Piulachs; Thomas Keller; Xavier Bellés

Abstract Patterns of juvenile hormone have been intensively studied in the cockroach Blattella germanica under different physiological situations. However, data have been mainly obtained in vitro, and refer to hormone synthesized by isolated corpora allata, whereas information available on hormone concentration in the hemolymph is restricted to adult females. In order to complement our studies in vitro, we have measured juvenile hormone titer in the hemolymph of B. germanica females in four characteristic physiological situations: penultimate and last instar nymphs, adults during the first vitellogenic cycle, and adults transporting egg cases (ootheca). In general, a significant positive correlation between rates of hormone synthesis and concentration in the hemolymph is observed. The main disparities appear in the penultimate day of the period of ootheca transport, where titer is high whereas synthesis is low, and on day 6 of the first vitellogenic cycle, where synthesis increases whereas titer decreases. At these stages, the observed disparities between synthesis and titer might be explained by differential action of degradation enzymes.


Forensic Science International | 1999

Analysis of psilocybin and psilocin in Psilocybe subcubensis GUZMÁN by ion mobility spectrometry and gas chromatography–mass spectrometry

Thomas Keller; Andrea Schneider; Priska Regenscheit; Richard Dirnhofer; Thomas Rücker; Jürgen Jaspers; Wolfgang Kisser

A new method has been developed for the rapid analysis of psilocybin and/or psilocin in fungus material using ion mobility spectrometry. Quantitative analysis was performed by gas chromatography-mass spectrometry after a simple one-step extraction involving homogenization of the dried fruit bodies of fungi in chloroform and derivatization with MSTFA. The proposed methods resulted in rapid procedures useful in analyzing psychotropic fungi for psilocybin and psilocin.


Forensic Science International | 1999

GC/MS determination of zolpidem in postmortem specimens in a voluntary intoxication

Thomas Keller; Andrea Schneider; Edith Tutsch-Bauer

An ingestion of an unknown quantity of Ivadal (zolpidem) tablets in a case of drug abuse is described. The authors report a new and fast method of analysing and determining the zolpidem concentration in postmortem specimens. Quantitation of zolpidem was performed by ethyl acetate extraction from alkalinized body fluids before GC/MS analysis. The analyses were performed without any complex sample clean-up steps and with little sample material. Postmortem concentrations of zolpidem in body fluids are given. The proposed method is a rapid procedure of analysis in cases of deliberate poisoning with the sedative-hypnotic drug, zolpidem.


Forensic Science International | 1997

Fatal overdose of clozapine

Thomas Keller; Akihiro Miki; Sabina Binda; Richard Dirnhofer

An ingestion of an unknown quantity of Leponex (clozapine) tablets in a suicide is described. Although clozapine is known for over 30 years now, relatively few cases of intoxications due to clozapine overdose have been reported. The authors report a new and quick method to analyze and determine the clozapine and N-desmethylclozapine concentration in body fluids. The analytes and an internal standard (zolpidem) were extracted from alkalinized samples into ethyl acetate before GC/NPD analysis. The proposed method resulted in a rapid procedure most useful in cases of deliberate poisoning with the neuroleptic drug Leponex.


Forensic Science International | 1998

Fatal chloroquine intoxication.

Thomas Keller; Andrea Schneider; Robert Lamprecht; Rolf Aderjan; Edith Tutsch-Bauer; Wolfgang Kisser

A suicidal ingestion of an unknown quantity of Resochin (chloroquine) tablets is described. Although chloroquine is known since 1934, intoxications due to chloroquine overdose are rather rare in European countries. The authors report on a new and fast method of analysing and determining the chloroquine concentration in body fluids and postmortem specimens. The analytes were extracted from alkalinized samples into ethyl acetate before GC/MS analysis. The analyses of chloroquine were performed without any complex sample clean-up steps and, in addition, with little sample material. The proposed method resulted in a rapid procedure most useful in cases of deliberate poisoning with the anti-inflammatory and antimalarial drug chloroquine.


Forensic Science International | 2000

Fatal intoxication due to dothiepin

Thomas Keller; Andrea Schneider; Edith Tutsch-Bauer

An ingestion of an unknown quantity of Harmomed (dothiepin and diazepam) capsules in a suicide is described. The authors report a new and fast method of analysing and determining the dothiepin concentration in postmortem specimens. Quantitation of dothiepin, and its metabolite desmethyldothiepin was performed by ethyl acetate extraction from alkalinized body fluids before GC-MS analysis. The analyses were performed without any complex sample clean-up steps and with little sample material. Postmortem concentrations of dothiepin, desmethyldothiepin, diazepam and desmethyldiazepam in body fluids are given. The proposed method is a rapid procedure for analysis in cases of deliberate poisoning with the antidepressant drug dothiepin.


Legal Medicine | 2009

Driving under the influence of drugs and alcohol in Salzburg and Upper Austria during the years 2003-2007

Thomas Keller; Andrea Keller; Edith Tutsch-Bauer; Fabio Monticelli

Until 2002 in Austria a blood sample could not be drawn due to regulations stipulated by the Austrian constitution. During the years 2003-2007 alcohol, pharmaceuticals and illicit drugs were analyzed in 1167 blood samples from cases of suspected and drugged drivers. In accordance with the findings of the EU-project Rosita, a wide variety of illicit drugs and medications could be found in blood samples of the drivers where cannabis (50%), opiates (20%), amphetamines (18%), cocaine (15%) and benzodiazepines (20%) were those with the highest prevalence. To enable police and medical officers to identify drivers under the influence of cannabis, a newly developed urinary road-site-test system, Check 24 (Protzek GmbH, Germany), with two different cut-off values for THCCOOH-glucuronide was used. So far, it was not possible to draw any conclusions from a cannabinoid positive urine sample to the actual influence of a driver due to the previous consumption of cannabis. Using this test a better differentiation between recent and temporal earlier consumption was possible. In addition to using the Check 24 system the technology of pupillography (AMTech GmbH, Germany) was applied in cases of drugged driving. For the first time the authors were able to predict the presence of at least one central nervous active substance in the blood of a drugged driver.


Legal Medicine | 2011

Another case of diethyl ether intoxication? A case report focusing on toxicological analysis

Fabio Monticelli; Ralf Kemmerling; Katja Schulz; Thomas Keller

Diethyl ether was widely used as an anesthetic agent in many countries in the second half of the 19th century and the first half of the 20th century. For this reason the majority of lethal cases involving diethyl ether reported during this period were associated with anesthesia. We present a case of asphyxial death by plastic-bag suffocation with additional detection of diethyl ether in autopsy specimens. Autopsy initially failed to reveal the cause of death. Macroscopic and microscopic findings as well as subsequent toxicological examination procedures and results are pointed out in the present case report. Headspace gas chromatography with flame ionization detection (HS-GC-FID) coupled with gas chromatography/mass spectrometry (GC-MS) proved to be the method of choice for fast and reliable analysis of unknown highly volatile substances (other than blood alcohol). In this case the detection of diethyl ether in autopsy specimens led to further investigations by the police at the death scene. During these investigations a bottle bearing a diethyl ether label was found and confiscated, which proved the insufficiency of prior death scene investigation. In order to evaluate the case from every possible angle, in such cases, especially when plastic-bag suffocation is suspected, we strongly recommend the collection of postmortem specimens in gas-tight vessels as well as the presence of a forensic expert at the death scene.


Journal of Cardiac Surgery | 2014

Cardiac amyloidosis as a potential risk factor for transapical transcatheter aortic valve implantation.

Fabio C. Monticelli; Sebastian N. Kunz; Thomas Keller; Sabine Bleiziffer

Transcatheter aortic valve implantation via transarterial or transapical access is an alternative therapy to treat high‐risk patients with severe symptomatic aortic stenosis. Despite growing experience, procedural complications may still occur. We herein report an 86‐year‐old female patient with fatal left ventricular rupture after transapical transcatheter aortic valve implantation with an Edwards Sapien prosthesis due to severe cardiac amyloidosis. doi: 10.1111/jocs.12305 (J Card Surg 2014;29:623–624)


Medicine Science and The Law | 2010

Pupil function as an indicator for being under the influence of central nervous system-acting substances from a traffic-medicine perspective

Fabio Monticelli; Fritz Priemer; Wolfgang Hitzl; Thomas Keller

In order to evaluate driving abilities of each traffic participant, standardised and objective measurement methods are needed. The applicability and value of infrared pupillography as an objective measurement method to indicate possible influence of central nervous acting substances has been demonstrated in former publications. Healthy test subjects (n = 41), as well as persons who were under the influence of drugs and/or medication (n = 105), were exposed to different light stimuli using infrared technology in order to demonstrate the relevance of specific parameters of the pupillary light reflex (PLR) in the field of traffic medicine. Based on former reported results, the statistical examination was extended to further parameters of the PLR, which again confirmed the high value of infrared pupillography as a reliable indicator of previous consumption of drugs and/or medication.

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