Determination of strength and deformation behavior of human cartilage for the definition of significant parameters.

In reconstructive surgery, an artificial supporting scaffold made from autogenous cartilage from the rib, the ear concha, or the nasal septum is used as a substitute for the destroyed endogenous tissue in the ear concha, the nose, the trachea, and in parts of the facial skeleton. For the successful use of polymer materials in reconstructive surgery, an exact knowledge of the material properties of the natural tissues is required. The applicability of conventional material test methods was examined with regard to the suitability of the test methodology. Materials properties are to be assessed for different specimen sizes and geometries. Human cartilage specimens from the septum, rib, and ear were subsected to the following test methods: (1) tension, (2) bending, (3) compression, and (4) micro-hardness measuring. Specimen geometry was evaluated for each experimental method by taking into account the dimensions of samples used in plastics testing as well as the appropriate model of miniaturization. Elastic properties determined using test methods (1), (2), and (3) are Et-sep=(7.2+/-3.4) MPa, Ef-rib=(8.8+/-2.9) MPa, and Ec-rib=(103+/-30) MPa. The micro-hardness values hpl fluctuate for septum from 1 to 4 N/mm2 and for the rib from 0.5 to 1.3 N/mm2. The experiments have shown that, beside the sex- and age-specific values recorded, the standard values and their variation are particularly influenced by preparation technique and by the conditions of storage. As a result of these first investigations, characteristic values for strength and deformation were determined under quasistatic and dynamic load conditions. The aim of this study was not the determination of statistically firmed properties, but the examination of the applicability of mechanical test methods of the polymer testing for these materials.

[Olfactory and gustatory disorders--causes, diagnosis and treatment]. / Riech- und Schmeckstörungen. So reparieren Sie die Sinne lhres Patienten.

Olfactory and gustatory disorders are by no means uncommon, and may be associated with an appreciable impairment of the patient's quality of life. In many cases, diagnosis and treatment is not easy, and necessitates interdisciplinary cooperation between the general practitioner, internist, ENT specialist, neurologist and psychiatrist. Many of the non-evidence-based treatments still applied in hospitals and the physician's office should, for reasons of quality control and to avoid polypragmasy possibly associated with undesirable side effects, be employed with reservations. With reference to the guidelines issued by the working group Olfactologie/Gustologie der Deutschen Gesellschaft für HNO-Heilkunde, Kopf- und Hals-Chirurgie (Olfactology/Gustology of the German Society of ENT Medicine, Head and Neck Surgery), a review of the causes, diagnosis and treatment of olfactory and gustatory disorders [3,4] is presented.

Observations on simultaneous perilymphatic motions and cochlear microphonics suppression.

Very low frequencies interfere in the intact cochlea with higher frequencies and suppress these depending on the vibration phase of the low-frequency sound. Physiological functions of the body, mediated, for example, by the eardrum or perilymph coupling with the cerebrospinal fluid, cause a low-frequency pressure modulation of the perilymph, which generates a synchronous perilymphatic motion resulting from the unevenly distributed compliances in the cochlea. This slow streaming causes a displacement of the entire basilar membrane, with as a consequence a postponement of the operating point of the mechanoelectrical transducer as a result of the pressure drop in the helicotrema and the narrow apical cochlear turn. In this contribution, interference phenomena are described, which are caused by spontaneous contractions of the tensor tympani muscle and by respiration-synchronous perilymphatic flow. These two test signals have trapezoidal and triangular impulse functions. In both cases, as suppression pattern of the cochlear microphonics level-time function, the second derivative of the pressure-time function was observed. The suppression is found to lie between 1 and 2 dB. It depends on the level of the suppressed sound and shows a compressive nonlinearity.

The metabolic reaction of the cochlea to unphysiological noise exposure.

Guinea pigs were exposed to continuous white noise of 120 dB SPL. The performance included a recording of CM, pO2, and metabolites in the perfusate of the perilymphatic spaces. The metabolic reactions observed following the exposure are limited. No evidence of an overstimulation or of an insufficiency of the energy metabolism in the cochlea could be found. The results suggest the metabolic processes to be secondary to the sound-dependent damage of the organ of Corti after irreversible mechanical destructions in the hair cells.

[Clinical and experimental use of ATP in internal ear diseases]. / ATP-Anwendung bei Innenohrerkrankungen in der Klinik und im Experiment

Intra-arterial ATP infusions with glucose and hyaluronidase were successful in 267 patients suffering from various inner ear disturbances but particularly in sudden deafness. Good clinical results were noted not only in early-treated but also in later cases. Recently, we have also used ATP with hyperbaric oxygen, being successful in cases which were previously treated without improvement. Investigations in guinea-pigs, using artificial hypoxia as a model for human sudden deafness failed because the patterns are not the same. So long as an increase of ATP in the cochlear cells cannot be demonstrated after the i.a. infusions, only an unspecific mechanism can be held responsible for the undoubted clinical successes.