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Biomedical subjects

B Kellner

Publications and source records attributed to B Kellner.

17 recordsLinked to original sources
PubMed2001

Smooth muscle electromyography.

This article addresses smooth muscle physiology, electromechanical and pharmacomechanical coupling, computed-based interpretations, and the role of electromyography in the diagnosis of erectile dysfunction.

Discriminant Analysis↗
PubMed2000

Computerized classification of corpus cavernosum electromyogram signals by the use of discriminant analysis and artificial neural networks to support diagnosis of erectile dysfunction.

Corpus cavernosum electromyogram (CC-EMG) provides diagnostic information on cavernous autonomic innervation and a measure of the degree to which the cavernous smooth muscle cells are intact. The complicated CC-EMG is evaluated and used in the diagnosis of patients suffering from erectile dysfunction. The evaluation procedure has been simplified by applying digital signal processing techniques. Since mathematically-based interpretations require quantitative data, spectral analysis was performed. The derived biosignals were analyzed by fast Fourier transform (FFT). Besides various other spectral parameters, specific frequency bands were determined in the power spectrum using factor analysis. The parameters were used for the computerized classification of normal and pathological CC-EMG data and the classification was performed using two independent methods: discriminant analysis (DA) and artificial neural networks (ANN). A medical expert analyzed a total of 200 CC-EMG recordings from patients with and without erectile dysfunction and separated these into normal (136) and pathological (64) cases. Although each independent method had already resulted in a relatively high number of correct classifications, the classification success rate could be slightly improved by using a combination of both classification methods. A total of 72.79% and 77.94% were successfully classified using DA and ANN, respectively. The combination of both methods increased the classification success to 80.15%. The results of this study enabled impartial evaluation of the CC-EMG signals for clinical diagnostic purposes of erectile dysfunction. This method provided an objective and easy way to analyze the CC-EMG. Furthermore, this results in patient diagnosis becoming an easier task for less experienced doctors, since little knowledge of the raw signal is needed.

Algorithms↗
PubMed1997

Computer-assisted evaluation of the smooth-muscle electromyogram of the corpora cavernosa by fast Fourier transformation.

OBJECTIVE: The aim of our study was to investigate analogous and digital recording of corpus cavernosum EMGs (CC-EMGs) in normal men according to criteria that were recently agreed upon in an international consensus workshop. METHODS: CC-EMGs were analogously and digitally registered from 37 normal subjects. Power spectra in the frequency domain were determined via fast Fourier transformation (FFT). RESULTS: Thirty-one of men showed identical or at least very similar electrical activity patterns in the analogous and digital registration. Needle penetration artifacts (investigated in 18 subjects) were found in 17/18 CC-EMGs during the first 20 min. Power spectra show a maximum of power at a frequency of 0.3 Hz with more than 90% of the power located between 0 and 5 Hz. CONCLUSIONS: Registration of CC-EMGs in normal men resulted in interindividually reproducible recordings. Age hardly affected CC-EMGs. Computer-assisted evaluation by FFT after elimination of artifacts was feasible. Thus, interpretation of the CC-EMG signals by a computer-aided expert system seems to be promising for clinical routine, in particular with respect to an increase in objectivity and a decrease in time needed for interpretation.

Adolescent↗
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↗
PubMed1978

Study of the antitumoral activity of S-carbamoyl-L-cysteine derivatives in animal experiments.

The antitumoral activity of three amino acid derivatives, S-carbamoyl-L-cysteine, S-ethyl-carbamoyl-L-cysteine, and S-chloroethyl-carbamoyl-L-cysteine, was studied. The ethyl and chloroethyl derivatives had a pronounced curative effect on certain animal tumors. It is interesting in the case of S-carbamoyl-L-cysteine that N-ethylization of the substance resulted in increased chemotherapeutic effectivity with no simultaneous change of the toxicity. According to various studies this effect is different in many respects from that of the known cytostatics, and a possibility of a specific selective or surface activity is raised.

Animals↗
PubMedDate not supplied

Improvement of lung preservation -- from experiment to clinical practice.

BACKGROUND: Reperfusion injury represents a severe early complication following lung transplantation. Among the pathogenetic factors, the high potassium content of Euro-Collins(reg) solution is discussed. MATERIAL AND METHODS: In a pig model of orthotopic left-sided lung transplantation we investigated the effect of Euro-Collins solution (EC: n = 6) versus low potassium dextran (LPD: Perfadex: n = 6). Sham-operated (n = 6) animals served as control. Transplant function, cellular energy metabolism and endothelial morphology served as parameters. In a clinical investigation, 124 patients were evaluated following single (EC: n = 31; LPD n = 37) or double (EC: n = 17; LPD n = 39) lung transplantation, whose organs where preserved with EC (n = 48) or LPD (n = 76). Duration of ischemia, duration of ventilation and stay on ICU were registered. Primary transplant function was evaluated according to AaDO(2) values. Cause of early death (30 days) was declared. RESULTS: Experimental results: After flush with EC and 18 h ischemia, a reduction of tissue ATP content (p < 0.01 vs inital value and LPD) was noted. Endothelial damage after ischemia was severe (p < 0.05 vs control), paO(2) was significantly decreased. CLINICAL RESULTS: In the LPD group, duration of ischemia was longer for the grafts transplanted first (SLTx and DLTx: p = 0.0009) as well as second (2. organ DLTx: p = 0.045). Primary transplant function was improved (day 0: SLTx: p = 0.0015; DLTx: p = 0.0095, both vs EC). Duration of ventilation and stay on ICU were shorter (n.s.). Reperfusion injury-associated death was reduced from 8% (EC) to 0 (LPD). CONCLUSION: In experimental lung preservation, LPD lead to an improved graft function. These results were confirmed in clinical lung transplantation. Clinical lung preservation, therefore, should be carried out by use of LPD.

Adult↗