Biomedical subjects

Werner Linss

Publications and source records attributed to Werner Linss.

6 recordsLinked to original sources

PubMed2006

The cochleogram of the guinea pig.

The cochleogram is an important tool to relate properties of the cochlea (e.g. hair cell loss, damaged hair cells) to their position in the cochlear turns, to calculate the average hair cell density, and to measure the length of the whole cochlea. In this work different methods of plotting cochleograms are compared. We suggest that a sector-wise division of the cochlea for counting a cochleogram has advantages over line diagrams that provide a higher spatial resolution but might lead to misinterpretations of the degree of missing hair cells. The scanning electron microscopic analysis of 171 guinea pig cochleas revealed a mean basilar membrane length of 16.4 +/- 1.4 mm (mean +/- standard deviation) with sector lengths of 6.9, 4.2, 3.2, and 1.9 mm, thus adding relevant information to the morphology of the guinea pig cochlea.

Animals↗

PubMed2006

Flow cytometry as a diagnostic tool for hereditary spherocytosis.

Flow cytometric analysis of eosin-5'-maleimide-labeled red blood cells has been proposed as a new method of identifying hereditary spherocytosis (HS). The aim of the present study was to analyze sensitivity and specificity of this method. Red blood cells from patients with HS (n = 58) revealed significantly lower mean channel fluorescence values than red blood cells from normal subjects (n = 110), unaffected HS family members (n = 8), and patients with other anemias (n = 44). Taking a mean channel fluorescence of 400.0 units as the threshold value identified by logistic regression, sensitivity and specificity of the test for HS were 96.6 and 99.1%, respectively. Flow cytometric analysis is a valuable screening test for the diagnosis of HS.

Anemia, Hemolytic↗

PubMed2005

Treatment of chondral defects by hydro jet. Results of a preliminary scanning electron microscopic evaluation.

INTRODUCTION: Arthroscopic methods in treatment of chondral defects aim to get smooth cartilage surfaces. Mechanical and thermal methods are used. Often the clinical results are poor or moderate. The treatment of chondral defects by using a hydro jet is an innovative measure. This study was aimed to evaluate the quality of the chondral surfaces after mechanical, thermal and hydro jet treatments in an in vitro scanning electron microscopy (SEM) study. MATERIALS AND METHODS: Femoral osteochondral pieces of the lateral condyle were obtained intraoperatively from patients undergoing total knee arthroplasty for primary knee OA. Partial-thickness cartilage degree II defects were smoothed by a mechanical shaver, bipolar radio frequency energy (RF) and hydro jet (84.1 KPa). SEM was carried out to evaluate the effects of the treatment. RESULTS: Mechanical shaving produces a rough surface with groves and open lying collagen fibers. The surface, after bipolar cool ablation (coablation) was also uneven. The matrix was destroyed by massive vacuolization. Hydro jet treatment produces a relatively smooth surface without open lying collagen fibers. CONCLUSION: It is not possible to produce even surfaces by mechanical shaving or bipolar treatment. Hydro jet treatment allows a precise cutting which causes a relatively smooth chondral surface.

Aged↗

PubMed2005

Frequency-specific cochlear damage in guinea pig after exposure to different types of realistic industrial noise.

For the causal evaluation of occupational hearing damage it is important to identify definitely the noise source. Here we tested, whether recordings of distortion product otoacoustic emissions (DPOAEs) in awake guinea pigs can distinguish the effects of different industrial noises. Six groups of 12 animals each were investigated before and over four months after a single 2 h exposure to specific, played-back industrial noise as well as before and for 2 months after impulse noise exposure. We compared broadband noise (buzz saw, bottle washing machine), low frequency noise (drawing press), and mid-frequency noise (bottle filling machine). All animals had stable DPOAE levels before noise exposure. Frequency specific decreases in DPOAEs were found after exposure to the different noises. Broadband noise diminished mostly all frequencies tested, whereas low- or mid-frequency noise had a greater effect on DPOAE evoked by middle and higher frequencies, respectively. DPOAE evoked by middle and higher frequencies were obliterated after impulse noise. Morphological analysis of the cochleae confirmed these alterations. OHC loss was found in the middle turns of the cochleae corresponding to the diminution of DPOAE. We conclude that different kinds of industrial noise tend to produce typical changes in DPOAE levels.

Animals↗

PubMed2005

Influence of image-capturing parameters on digital X-ray radiogrammetry.

The purpose of this study was to evaluate the importance of different image-capturing conditions, which might influence the characteristics of radiographs and, consequently, impact calculations of bone mineral density (BMD) and Metacarpal Index (MCI) using digital X-ray radiogrammetry (DXR). Radiographs of the left hand of deceased males were acquired three times using systematically varied parameters: 4-8 miliamp seconds (mA); 40-52 kV; film-focus distance (FFD); 90-130 cm; film sensitivity, 200/400; and different image modalities (conventional vs original digital radiographs as well as digital printouts). Furthermore, the interradiograph reproducibility using both conventional equipment and printouts vs originals of digital images and the intraradiograph reproducibility (either conventional or digital printouts) were evaluated. All BMD and MCI measurements were obtained with the DXR technology. The interradiograph reproducibility of DXR-BMD using conventional images under standardized conditions (6 mAs; 42 kV; 1 m FFD; film sensitivity of 200) was calculated to be coefficient of variation (CV) = 0.49% for Agfa Curix film and CV = 0.33% for Kodak T-MAT-Plus film, whereas reproducibility error using digital images ranged from CV = 0.57% (digital printouts; Philips) to CV = 1.50% (original digital images; Siemens). The intraradiograph reproducibility error was observed to be CV = 0.13% (conventional; Kodak film) vs CV = 0.27% (digital printouts; Philips). The BMD calculation was not noticeably affected by changes of FFD, exposure level, or film sensitivity/film brand, but was influenced by tube voltage (CV = 0.99% for Kodak film to CV = 2.05% for Siemens digital printouts). No significant differences were observed between the BMD and MCI data. DXR provides measurements of MCI and BMD with high precision and reproducibility. The measurements are unaffected by all tested image-capturing conditions, with the exception of tube voltage. In addition, different digital image devices clearly have an effect on DXR reproducibility.

Bone Density↗

PubMed2003

[Problems in the development of a comprehensive three-dimensional databank of the human skull for the preoperative preparation of an exact implant for the treatment of bone defects].

Various human skulls were scanned with a laser scanner. Impressive Landmarks of the skull were determined and tested to be comparable stored in a uniform coordinate system for subsequent 3-d reconstruction. The Rhinion, the Nasion, the Spina nasalis anterior, the Prosthion, and the Opisthokranion were found to be very qualified for the adjustment in the median plane. The frontal plane was defined by the Rhinion and the Spina nasalis anterior. The Mastoidealia, the Zygomaxillaria and the Orbitalia were used to align the skull in the horizontal plane. The qualification of the database as a fundamental part for the comparison of human skulls and for the discovery of similarities to patient skulls with bone defects is demonstrated by means of 2 clinical cases. A subsequent result is the application to manufacture fitting implants of biocompatible materials for covering huge side-overlapping bone destructions.

Databases, Factual↗