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Biomedical subjects

W Denk

Publications and source records attributed to W Denk.

At least 55 records · Page 3Linked to original sources

Shots fired with silencers--a report on four cases and experimental testing.

Four cases of homicide, in which silenced firearms were used, are reported and supplemented by data from experimental investigations regarding wound features, marks, traces, and ballistic behavior. Wound features are largely determined by the construction of the silencer. In one case, even a muzzle imprint was produced by a silenced weapon fired at contact range. In general, silencers are likely to result in a decrease in bullet energy and accelerated energy release in the target (tissue). In terms of wound morphology, silencers produced a reduction in or even a lack of the contact ring (ring of dirt). In close-range and contact wounds, any features indicative of shots fired at close range were missing (such as soot deposit and powder tattooing). It is also worth mentioning that biological matter may get into the silencer in shots fired at contact range.

Adult↗

Two-photon laser scanning fluorescence microscopy.

Molecular excitation by the simultaneous absorption of two photons provides intrinsic three-dimensional resolution in laser scanning fluorescence microscopy. The excitation of fluorophores having single-photon absorption in the ultraviolet with a stream of strongly focused subpicosecond pulses of red laser light has made possible fluorescence images of living cells and other microscopic objects. The fluorescence emission increased quadratically with the excitation intensity so that fluorescence and photo-bleaching were confined to the vicinity of the focal plane as expected for cooperative two-photon excitation. This technique also provides unprecedented capabilities for three-dimensional, spatially resolved photochemistry, particularly photolytic release of caged effector molecules.

Animals↗

[Carotid and vertebral artery circulation in forearm choke holds in Doppler sonography].

By means of continuous wave doppler the effect of two choke holds (Carotid sleeper, Nami-juji-jime) on the carotid and vertebral arteries was investigated. For both choke holds, which are characterized by pressure on lateral parts of the neck, we found an obstruction up to a complete stop of flow. The degree of obstruction depended on the direction of force. The vertebral artery can be compressed between the subclavian artery and the foramina transversaria, therefore it was most effective to press on the lower neck. Tensing the neck muscles can reduce the effect of choking.

Asphyxia↗

[Forensic medicine literature databank. Goals and uses].

In addition to existing, international database systems we started building up a forensic-medical database. Whereas the current systems offer a cross section of the newest medical knowledge, we wanted to reach a review over the most important journals specialized in forensic medicine, starting from their beginning. In this way one gets informations over empirical knowledge and casuistry, which are of great importance in forensic medicine. As technical basis we use a personal computer and the dBase III database system.

Databases, Factual↗

Synthesis, photochemistry, and biological activity of a caged photolabile acetylcholine receptor ligand.

A biologically inert photolabile precursor of carbamoylcholine has been synthesized; it is photolyzed to carbamoylcholine, a well-characterized acetylcholine analogue, with a half-time of 40 microseconds at pH 7.0 and a quantum yield of 0.8. The compound, N-(alpha-carboxy-2-nitrobenzyl)carbamoylcholine, was synthesized from (2-nitrophenyl)glycine. The photolysis rates (of five compounds) and the biological activity (of two compounds) were determined, and both properties were found to depend on the nature of the substituents on the photolabile protecting group. Laser pulse photolysis at wavelengths between 308 and 355 nm was used to investigate the wavelength dependence, quantum yield, and rate of the photolysis reaction. Photolysis products were isolated by high-performance liquid chromatography and identified by chemical and spectroscopic analysis and by their ability to activate the nicotinic acetylcholine receptor. BC3H1 muscle cells containing those receptors and a cell-flow method were used in the biological assays. The approach described may be useful in the preparation and characterization of other photolabile precursors of neurotransmitters that contain amino groups. The importance of these rapidly photolyzed, inert precursors of neurotransmitters is in chemical kinetic investigations of the reactions involving diverse neuronal receptors; such studies have been hampered because the available techniques have an insufficient time resolution.

Carbachol↗

[A transition zone phenomenon of the skin in cadavers lying in bath water].

In three cases a phenomenon is reported, seen on the skin of bodies found dead after a longer time of lying in bathtubs filled with water. The sign was parallel to the surface of the water and showed a breadth up to about 1 cm. Contrary to the surrounding skin, the mark was characterized by paleness and clearly les distinct formation of postmortem alterations as put-refaction. Searching for an explanation, temperature measurements were performed in model. The results showed the marginal paleness of the skin to be a thermal phase transition phenomenon. This mark has a forensic message too: it demonstrates a longer remaining of the corpse in the corresponding position, is a statement concerning the high of the water level, and allows a reconstruction of the original situation after manipulation, but is no sign of vital reaction.

Adult↗

[A fatality caused by heparin overdose].

Because of suspected pulmonary embolism 550.000 I.U. of heparin were administered instead of 55.000 I.U. of heparin within 24 h to a 62 year old patient. The man died because of cerebral hemorrhage the following day. Autopsy findings are reported and difficulties in medical expertise are discussed.

Brain↗

Mechanical properties of sensory hair bundles are reflected in their Brownian motion measured with a laser differential interferometer.

By optically probing with a focused, low-power laser beam, we measured the spontaneous deflection fluctuations of the sensory hair bundles on frog saccular hair cells with a sensitivity of about 1 pm/square root of Hz. The preparation was illuminated by two orthogonally polarized laser beams separated by only about 0.2 microns at their foci in the structure under investigation. Slight movement of the object from one beam toward the other caused a change of the phase difference between the transmitted beams and an intensity modulation at the detector where the beams interfered. Maintenance of the health of the cells and function of the transduction mechanism were occasionally confirmed by measuring the intracellular resting potential and the sensitivity of transduction. The root-mean-square (rms) displacement of approximately 3.5 nm at a hair bundle's tip suggests a stiffness of about 350 microN/m, in agreement with measurements made with a probe attached to a bundle's tip. The spectra resemble those of overdamped harmonic oscillators with roll-off frequencies between 200 and 800 Hz. Because the roll-off frequencies depended strongly on the viscosity of the bathing medium, we conclude that hair-bundle motion is mainly damped by the surrounding fluid.

Animals↗

[Installation of electronic data processing at the Vienna Forensic Medicine Institute--experiences and outlook].

1985 the systematic use of personal computers in the Viennese institute of forensic medicine began. Due to the big engineering progress there was no more need to connect to a computer center. A gradual installation and a strict determination of requirements are important for computer systems, whereas a personal computer might be useful for word processing only as well.

Austria↗

[Fatal myocardial rupture as a complication in removal of a pacemaker catheter].

A case of myocardial rupture and cardiac tamponade after pulling out a tined electrode is reported. Pacemaker failure caused by lead fractures is a common reason for removing the electrode. In case of a self-anchoring lead alternative methods should be considered. The opportunity for immediate surgical help must be given.

Aged↗

[Mechanism of action of forearm strangulation technics].

Two cases of death caused by the use of choke holds are reported; four different types of choke holds used in combative sports were investigated. In experiments on corpses it was found that even relatively little expenditure of strength can impede the passage of fluid not only through the internal carotid artery but also through the vertebral artery, depending on the respective choke hold. Fractures of the larynx cannot be expected as often as after typical throttling. However, a quick loss in defense capacity was found experimentally, and this always occurred within 15 s. Pulse frequency and blood pressure were recorded. Injuries to the neck are minor and may not be typical.

Adult↗

[Fatal intracranial increase in pressure caused by a colloid cyst of the 3d ventricle not diagnosed intra vitam].

The case is reported of a 26 year-old man with a colloid cyst of the third ventricle (paraphyseal cyst; neuroepithelial cyst), which gave rise to a fatal increase in intracranial pressure. Despite repeated hospitalisation the diagnosis was not established prior to death. This report serves as a reminder that this rare disorder must be considered in the differential diagnosis of conditions causing increased intracranial pressure in view of the life-saving therapeutic management required to avert a fatal outcome.

Adult↗

[Air embolism following arthroscopy--autopsy findings and forensic medicine aspects].

An iatrogenic cause of air embolism with a fatal outcome is reported that occurred in a case in which arthroscopy of the knee had been carried out. Even after worldwide use of arthroscopy for many years, this complication has never been seen until now. At autopsy, when air bubbles were observed in the right heart chamber and in the vena cava inferior, only the knee joint was taken into consideration as the air-access route. The access of air was detected by means of arthroscopy on the corpse, combined with a special autopsy technique and shown experimentally. Insufflated air had entered via a fracture of the tibial articular surface and then passed through the spongiosa into the femoral vein. These findings are of far-reaching clinical consequence because the indication for arthroscopy by gas insufflation must be reconsidered again. Finally, the medicolegal aspects of such an incident are discussed.

Adolescent↗