Methylpendolmycin, a new indole alkaloid with an N-methylisoleucine moiety incorporated in the nine-membered indolactam ring, has been isolated from an actinomycete culture of Nocardiopsis. Methylpendolmycin exhibited inhibition of phorbol ester binding to protein kinase C. Its structure was assigned on the basis of spectroscopic data.

Actinomycetales↗

PubMedDate not supplied

Continuous wavelet analysis as an aid in the representation and interpretation of electrogastrographic signals.

This paper presents an application of the continuous wavelet transform (CWT) in the analysis of electrogastrographic (EGG) signals. Due to the nonstationary nature of EGG signals, the CWT method, which uses multiresolution scaled windows, gives a better time-frequency resolution than the short-time Fourier transform, which uses a fixed window. Spike activity due to gastric contraction was investigated through experiments on dogs. During spike activity we observed an increase in magnitude of the slow wave and the appearance of a low frequency component with half the frequency of the slow wave. Studies of the EGG signals from the small intestine are also presented to investigate the hypothesis that its slow wave might be confounded with spike activity in the stomach due to the similarity of their frequency ranges.

Animals↗

PubMedDate not supplied

Time-frequency distribution technique in biological signal processing.

Time-frequency distribution (TFD) has gained wide acceptance for deterministic non-stationary signal processing, particularly for biological signals, in both basic research and commercial production. This paper presents the results of a comparison of the TFD technique with other methods for determining physiologic parameters, particularly the ventricular ejection time (VET) and (dZ/dtmax), the differentiation of the thoracic-fluid signal Z0 from non-stationary impedence cardiography dZ/dt. The TFD technique was found to be more accurate--in terms of both time and signal magnitude--than traditional methods such as the baseline and ensemble-averaging techniques when compared with phonocardiograms and hand calculations by experts in the field. It is shown that TFD can also reduce ventilatory/respiratory noise, electrical and muscle noise, and patient-motion artifacts. Correlation analysis and regression analysis as well as Bland-Altman studies showed stronger correlational methods tested.

Algorithms↗