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M Suckfüll

Publications and source records attributed to M Suckfüll.

7 recordsLinked to original sources
PubMed1996

Evaluation of TEOAE and DPOAE measurements for the assessment of auditory thresholds in sensorineural hearing loss.

Transiently evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emissions (DPOAE) can be quantified concerning their amplitude and frequency. They are known to be diminished or absent in sensorineural hearing loss. It is therefore of interest how TEOAE and DPOAE correlate with the auditory threshold and whether the auditory threshold can be predicted by these variables. In a cross sectional study of 61 patients (102 ears) with sensorineural hearing loss, auditory threshold, tympanometry, stapedius reflexes, TEOAE and DPOAE were measured. Correlation coefficients of the hearing loss (0.5-6 kHz) and the amplitude of the distortion product 2f1-f2 (0.46 4 kHz) respectively TEOAE amplitude (1-4 kHz) were computed. TEOAE showed lower correlation coefficients and less frequency specificity than DPOAE. In order to increase the correlations with the auditory threshold we fitted a multivariate linear regression model with TEOAE and DPOAE simultaneously as predictors for the auditory threshold gaining 95% prediction intervals of 19-39 dB depending on the frequency investigated. By restricting the hearing loss to a maximum of 70 dB HL the 95% prediction interval of the auditory threshold could be decreased to 18-26 dB. Further improvements can be expected if the high inter- and intraindividual variability of TEOAE and particularly DPOAE measurements can be reduced. The results allow us to use TEOAE and DPOAE in addition to click-evoked brainstem audiometry in order to provide more frequency specific information about the hearing loss in newborns, which is of the utmost importance for an ideal fitting of hearing aids.

Acoustic Impedance Tests↗
PubMed1995

[A new method for measuring internal ear circulation using colored microspheres].

The pathogenesis of sudden hearing loss is as yet unknown. Vascular disturbances are thought to play a major role, but they cannot be diagnosed clinically. We have therefore developed an animal model which allows measurements of the cochlear blood flow (CBF) and function. For CBF measurements a new technique based on coloured microspheres was developed. New Zealand rabbits were anaesthetised, ventilated and blood pressure and heart frequency were continuously monitored. 6 x 10(6) microspheres of one colour were injected in the left ventricle; different colours are available and allow multiple measurements. The amount of microspheres trapped in the capillary bed of the cochlea depends on the regional blood flow. An arterial reference blood sample makes it possible to calculate absolute values of the regional blood flow in the cochlea. The amount of microspheres trapped in the cochlea was determined microscopically after dissecting, dissolving and filtrating the cochlea. Measurements of the CBF in a control group (5 rabbits, 10 inner ears) at the beginning and after 120 minutes were performed. Mean CBF was 3.8 +/- 1.1 microliters/min and 4.3 +/- 1.3 microliters/min. The coloured microsphere technique allows repeated measurements of the CBF with good reproducibility and an acceptable standard deviation. CBF can be measured in absolute values, which is of advantage for determining a lower limit of the CBF for the cochlea function.

Animals↗
PubMed1994

Immunohistological studies of complement activation after xenogeneic perfusion of a working heart model.

Transplantation of organs from one species to another leads to immediate hyperacute rejection. Activation of complement is one important factor involved in this process. Whether complement activation is induced by preformed natural antibodies (PNAbs) via the classical pathway or by an "activator surface" via the alternative pathway is unclear. In order to simulate the relevant clinical situation of animal donor/human recipient we perfused working porcine hearts ex vivo with human blood. This also offered the possibility to study the process of complement activation in a precisely defined system with human complement proteins. PNAb titer and complement lytic activity of the plasma were measured. Immunohistological stainings for IgG, IgM, C1q, C4, C3d, C5-9, factor B, and properdin were performed on tissue sections of the left ventricle. PNAb titer almost totally disappeared within the first 5 min of perfusion. Complement lytic activity of the classical pathway decreased similarly within the first 3 h of xenogeneic and autologous perfusion from 70% to 40%. More detailed immunohistological studies revealed positive staining for C3d on endothelium and myocardium of ex vivo perfused xenogeneic hearts. Complement-induced cytotoxicity was proven by the presence of C5-9 (membrane attack complex). However, hardly any C1q and C4 could be found in the ex vivo xenogeneic perfused hearts. Staining for factor B was positive and proved activation via the alternative pathway. Beyond that, the presence of properdin binding even indicated an upregulation of the alternative pathway C3 convertase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Evolutionary and immunological aspects of xenotransplantation.

Immunological aspects in xenotransplantation are directly linked to evolutionary aspects. The immunological network with its high antigen specificity and species-specific interactions was developed to fight against the host's outside world including xenografts. The tremendous amount of reaction and mechanisms triggered by the performed natural antibody-endothelial cell reaction clearly indicates that only basic changes might overcome these problems. Even the introduction of transgenic donors might not be sufficient to modify more than one parameter, for example, complement activity. Total depletion of preformed natural antibodies is not compatible with normal life and the regulation of hormones and enzymes under xenogeneic conditions has just been discovered. Cellular mechanisms depend, as far as we know, on the delicate system of receptors, interleukins, and MHC antigens. From today's very early results we know that major changes exist already between closely related species. The investigation of xenogenic mechanisms has opened a totally new field of immunological interactions. Up to now there are no signs of solution to bridge clinically relevant times with xenogenic organs from widely divergent suitable donors with promising quality of life.

Animals↗
PubMedDate not supplied

[Tissue pO2 measurement in taut back musculature (m. erector spinae)].

Measurements with polarographic needle probes in fibromyalgic muscles (mm. erectores spinae) revealed an elevated mean tissue-pO2. The total mean tissue-pO2 in the patient group was significantly higher than that in the control group. Greater pathological tension in fibromyalgic muscles increases the mean tissue-pO2. The distribution of local tissue-pO2 values was normal; there was no evidence of small hypoxic areas in the muscle. The elevated tissue-pO2 in fibromyalgic muscles could either be explained by an increase in local blood flow or by disturbance of oxygen-utilization of the muscle cells. The mean tissue-pO2 in patients treated with NSAD was lower than in patients without this treatment. Myogelosises (i.e., circumscript tautness in muscles, that, contrary to fibromyalgic muscles, do not relax under general anesthesia) showed low tissue-pO2 values and even hypoxia in the core. In myogelosises, pain could be hypoxic in nature. However, in fibromyalgic muscles no evidence for hypoxia or hypoxia-related pain could be found.

Adult↗