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Biomedical subjects

C Hartung

Publications and source records attributed to C Hartung.

At least 37 records · Page 2Linked to original sources
PubMed1996

Application of factor analysis for the determination of specific frequency bands in corpus cavernosum EMG power density spectra.

Corpus cavernosum electromyogram (CC-EMG) recording provides diagnostic information on cavernous autonomic innervation and the intact state of cavernous smooth muscle cells. Evaluation of these signals is time consuming and complex. Therefore, we attempted to facilitate their interpretation and to increase their objectivity by using computer-based digital signal processing. Spectral parameters were used as a starting point for this analysis, which were calculated from the Fourier-transformed time domain CC-EMGs. Factor analysis was applied to determine specific frequency bands in the CC-EMG power density. Two hundred power spectra, taken from normal subjects (n = 66) and from patients suffering from erectile dysfunction (n = 134), constituted the basic data. As a result of applying factor analysis, four specific frequency bands were depicted: 0.0-0.3, 0.3-3.5, 3.5-6.0 and 6.0-10.0 Hz. The results of this study form the basis for further mathematical evaluation and calculation of the CC-EMG for clinical and diagnostic purposes.

Adult↗
PubMed1996

Mechanical testing of isolated senile human eye lens nuclei.

Phacoemulsification is a cataract surgery technique during which the eye lens nucleus is carefully dissected by an oscillating hollow needle simultaneously serving as a suction line for lens fragments. As the success of this procedure depends greatly on the mechanical properties of the nucleus, the basic mechanical properties of extracted senile human eye lens nuclei were studied. For this purpose a novel measuring system had to be developed enabling the study of the biomaterial's responses to any chosen excitation function. Either force- or displacement-controlled testing signals can be selected serving as a one-dimensional input. The resultant quantity can be recorded in the time or frequency domain. An almost linear viscoelastic behavior of lens nuclei is observed. Typical phenomena such as hysteresis, creep, relaxation, and a frequency-dependent compliance are evaluated. The ultimate strength of the specimen is studied by penetration tests. Finally the possible correlation between mechanical and optical parameters of lens nuclei is discussed. If correlated, a surgeon could use this information when deciding whether an extracapsular extraction or a phacoemulsification should be the preferred approach.

Aged↗
PubMed1994

Neuroparacoccidioidomycosis: case reports and review.

Cerebral and cerebellar masses occurred in patients with paracoccidioidomycosis. Correct diagnosis was delayed due to overlooking the abnormal lung roentgenograms and the history of previous disease in a different localization. The fungus was identified through biopsy and direct examination of the samples. In two patients necropsy confirmed the diagnosis. None of the patients responded to amphotericin B or cotrimoxazole. A 10 year English and Latin American literature review on neuroparacoccidioidomycosis was performed through a MEDLINE and LILACS (Latin American Literature Search System) data base systems.

Amphotericin B↗
PubMed1993

Ecological control of hospital engineering operations.

Environmental protection must be accomplishable in a hospital. Thus the goals have to be set in such a way that they are achievable. The track towards a positive environmental balance should be passable, ie environmental protection has to be on the people's mind and not on some single persons'. Environmental protection in the hospital starts in the purchasing department. If hospitals show an environmentally conscious demand, the industry will react with the supply of non-polluting products in order to not lose this market sector. Medical and the remaining hospital services may contribute to the protection of the environment by avoiding, reducing, and recycling waste. The responsibility for environmentally protective measures, such as noise reduction, sewage- and waste treatment, and avoidance of air pollution lies with hospital engineering. Operations (measuring, controlling) and maintenance (inspecting, servicing, overhauling) have to be available, safe, and economical. Thus the ecological demands for operations control are identically satisfied. The only task of the administration remaining is to support environmental consciousness and practice of environmental protection, to distribute attained knowledge and to survey the developments. Good environmental practice has to quantify environmental protection in the hospital.

Air Pollution↗
PubMed1988

[Roentgenologic aspects in the control of a completely implanted catheter system (Port) for parenteral nutrition].

A potential complication of totally implanted venous access systems is the extravasation due to faulty puncture or accidental needle dislodgement. It is important to differentiate this complication from a leakage of the system. A port system was explanted and replaced because an extravasation was misinterpreted as a leakage. Therefore it is necessary to know about the radiological aspects for controlling such a system.

Catheters, Indwelling↗
PubMed1975

[The biomechanics of hyaline cartilage under distension stress].

UNLABELLED: The mechanical properties of costal cartilage specimens from cattle were tested under periodical compressive loads. The specimens were put between the compression plates of an electronic materials testing machine and were exposed to defined deformations and deformation rates. On the basis of these induced periodical deformation-time curves as input functions we obtained force-time curves as output functions. RESULTS: (1) The cyclic force-time curves generated by deformation-time input functions with constant amplitudes initially showed a general decrease of force peaks until a force-time curve with constant amplitudes gradually arose. (2) If periodically loaded after a constant deformation had taken place the force peaks increased, at first pronouncedly but later diminishing. We named this the 'peak increase phenomenon'. (3) The mechanorheological curves of hyaline cartilage can be explained approximately by the viscoelastic behaviour of microfibrils in a parallel arrangement with the elastoviscous properties of cartilaginous ground substance.

Animals↗