Der Stellenwert der dynamischen Posturographie (Equitest®) bei gutachterlichen Beurteilungen

Quantification of local zinc and tungsten deposits in bone with LA-ICP-MS using novel hydroxyapatite-collagen calibration standards

Tungsten has recently emerged as a potential toxicant and is known to heterogeneously deposit in bone as reactive polytungstates. Zinc, which accumulates in regions of bone remodeling, also has a heterogenous distribution in bone. Determining the local concentrations of these metals will provide valuable information about their mechanisms of uptake and action. A series of bone (BN), 7:3 hydroxyapatite:collagen (HC), and hydroxyapatite (HA) standards were spiked with tungsten and zinc and used as calibration standards for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of bone tissue. The analytical performance of these standards was studied and validated at different step sizes using NIST SRM 1486 Bone Meal. The effect of matrix-matched calibration was assessed by comparing the calibration with BN and HC standards, which incorporate both inorganic and organic components of bone, to that of HA standards. HC standards were found to be more homogenous (RSD < 10%) and provide a linear calibration with better accuracy (R2 > 0.994) compared to other standards. The limits of detection for HC at a 15 μm step size were determined to be 0.24 and 0.012 μg g-1 for zinc and tungsten, respectively. Using this approach, we quantitatively measured zinc and tungsten deposits in the femoral bone of a mouse exposed to 15 μg mL-1 tungsten for four weeks. Localized concentrations of zinc (942 μg g-1) and tungsten (15.7 μg g-1) at selected regions of enrichment were substantially higher than indicated by bulk measurements of these metals.

Femtosecond laser is effective tool for zona pellucida engraving and tagging of preimplantation mammalian embryos

PURPOSE

Our purpose was to study whether application of femtosecond laser pulses for alphanumeric code marking in the volume of zona pellucida (ZP) could be effective and reliable approach for direct tagging of preimplantation embryos.

METHODS

Femtosecond laser pulses (wavelength of 514 nm, pulse duration of 280 fs, repetition rate of 2.5 kHz, pulse energy of 20 nJ) were applied for precise alphanumeric code engraving on the ZP of mouse embryos at the zygote stage for individual embryo marking and their accurate identification. Embryo quality assessment every 24 h post laser-assisted marking as well as immunofluorescence staining (for ICM/TE cell number ratio calculation) were performed.

RESULTS

Initial experiments have started with embryo marking in a single equatorial plane. The codes engraved could be clearly recognized until the thinning of the ZP prior to hatching. Since embryo may change its orientation during the ART cycle, multi-plane code engraving seems to be more practical for simplifying the process of code searching and embryo identification. We have marked the ZP in three planes, and no decrease in developmental rates as well as no morphological changes of embryos post laser-assisted engraving have been observed as compared to control group embryos.

CONCLUSIONS

Our results demonstrate the suitability of femtosecond laser as a novel tool for noninvasive embryo tagging, enabling embryo identification from day 0.5 post coitum to at least early blastocyst stage. Thus, the versatility and the potential use of femtosecond lasers in the field of developmental biology and assisted reproduction have been shown.

[Psychometric instruments for the diagnosis of tinnitus]

Tinnitus is a very complex phenomenon with various mechanisms of origin. Multimodal and interdisciplinary treatment is the most effective form of treatment for patients with chronic tinnitus. In order to assess existing comorbidity in tinnitus patients as well as to treat the patients individually, a comprehensive and differentiated diagnosis is needed. Since standardized guidelines for the use of relevant instruments in the diagnosis of tinnitus have been lacking hitherto, we present here psychometric questionnaires which have already been used effectively in the research, diagnosis and therapy of tinnitus in the present article. The questionnaires measure the severity of tinnitus, depression and anxiety, the perceived stress, personal resources as well as the quality of life of patients.

[Pharmacotherapy of acute and chronic hearing loss]

The aetiology of acute hearing loss is mostly idiopathic like sudden sensorineural hearing loss and rarely infectious or vascular. Several studies and meta-analyses of pharmacotherapy are reviewed: In chronic tinnitus there is no indication for pharmacotherapy; sometimes a possible psychosomatic comorbidity has to be treated with psychopharmaceutical agents. Despite a low level of evidence treatment with steroids and initially plasma expanding infusions is recommended for acute tinnitus if there is no spontaneous remission. Intratympanic steroid therapy can be used as an alternative if there is severe hearing loss together with tinnitus.

Moment measurement accuracy of a parallel spherical robot for dynamic posturography

This paper characterizes the moment measurement accuracy for a novel parallel spherical robot (SR) for dynamic posturography, controllable by position or impedance. The SR consists of three linear motors placed on a support base, a moving base, and three passive arms equipped with uniaxial load cells permitting impedance controlled perturbations. To evaluate the accuracy, a subject stood still on the SR, set in position control mode, while selected sinusoidal trajectories were applied. The moments computed by the load cells were compared to the value measured by a six-component force platform, placed on top of the rotating base. For the intended application of the SR, the errors were negligible with the worse case of only 4 Nm in a total of 15 trials (five conditions, three repetitions). The observed moment error was related mainly to the intrinsic accuracy of the sensors, equal to about 7 N. To demonstrate clinical applicability, the platform was set to impedance control mode and a protocol was tested with a 12-year-old girl with brain injury and a group of four healthy subjects. In total, 24 trials (eight conditions, three repetitions) were recorded for each subject. The results of this pilot study identified distinctive postural behaviors and therefore showed that the SR can be considered as an effective tool for dynamic posturography.

Morphological effects of nanosecond- and femtosecond-pulsed laser ablation on human middle ear ossicles

We evaluate the feasibility of nanosecond-pulsed and femtosecond-pulsed lasers for otologic surgery. The outcome parameters are cutting precision (in micrometers), ablation rate (in micrometers per second), scanning speed (in millimeters per second), and morphological effects on human middle ear ossicles. We examine single-spot ablations by a nanosecond-pulsed, frequency-tripled Nd:YAG laser (355 nm, beam diameter 10 microm, pulse rate 2 kHz, power 250 mW) on isolated human mallei. A similar system (355 nm, beam diameter 20 microm, pulse rate 10 kHz, power 160-1500 mW) and a femtosecond-pulsed CrLi:SAF-Laser (850 nm, pulse duration 100 fs, pulse energy 40 microJ, beam diameter 36 microm, pulse rate 1 kHz) are coupled to a scanner to perform bone surface ablation over a defined area. In our setups 1 and 2, marginal carbonization is visible in all single-spot ablations of 1-s exposures and longer: With an exposure time of 0.5 s, precise cutting margins without carbonization are observed. Cooling with saline solution result is in no carbonization at 1500 mW and a scan speed of 500 mms. Our third setup shows no carbonization but greater cutting precision, although the ablation volume is lower. Nanosecond- and femtosecond-pulsed laser systems bear the potential to increase cutting precision in otologic surgery.

Local inner-ear drug delivery and pharmacokinetics

Several drugs that are applied directly to the inner ear are in widespread clinical use for the treatment of inner-ear disorders. Many new substances and drug delivery systems specific to the inner ear are under development and in some cases are being evaluated in animal experiments and in clinical studies. However, the pharmacokinetics of drugs in the inner ear is not well defined and the field is plagued by technical problems in obtaining pure samples of the inner-ear fluids for analysis. Nevertheless, a basic understanding of the mechanisms of drug dispersal in the inner ear has emerged, which facilitates the design and interpretation of future pharmacokinetic studies.