Application of the nonlinear methods in pneumocardiogram signals.

In this work, the pneumocardiogram signals of nine rats were analysed by scale index, Boltzmann Gibbs entropy and maximum Lyapunov exponents. The scale index method, based on wavelet transform, was proposed for determining the degree of aperiodicity and chaos. It means that the scale index parameter is close to zero when the signal is periodic and has a value between zero and one when the signal is aperiodic. A new entropy calculation method by normalized inner scalogram was suggested very recently. In this work, we also used this method for the first time in an empirical data. We compared the both methods with maximum Lyapunov exponents and observed that using together the scale index and the entropy calculation method by normalized inner scalogram increases the reliability of the pneumocardiogram signal analysis. Thus, the analysis of the pneumocardiogram signals by those methods enables to compare periodical and/or nonlinear aspects for further understanding of dynamics of cardiorespiratory system.

Significance of using a nonlinear analysis technique, the Lyapunov exponent, on the understanding of the dynamics of the cardiorespiratory system in rats.

BACKGROUND/AIM: Pneumocardiography (PNCG) is the recording method of cardiac-induced tracheal air flow and pressure pulsations in the respiratory airways. PNCG signals reflect both the lung and heart actions and could be accurately recorded in spontaneously breathing anesthetized rats. Nonlinear analysis methods, including the Lyapunov exponent, can be used to explain the biological dynamics of systems such as the cardiorespiratory system. MATERIALS AND METHODS: In this study, we recorded tracheal air flow signals, including PNCG signals, from 3 representative anesthetized rats and analyzed the nonlinear behavior of these complex signals using Lyapunov exponents. RESULTS: Lyapunov exponents may also be used to determine the normal and pathological structure of biological systems. If the signals have at least one positive Lyapunov exponent, the signals reflect chaotic activity, as seen in PNCG signals in rats; the largest Lyapunov exponents of the signals of the healthy rats were greater than zero in this study. CONCLUSION: A method was proposed to determine the diagnostic and prognostic values of the cardiorespiratory system of rats using the arrangement of the PNCG and Lyapunov exponents, which may be monitored as vitality indicators.

Significance of apoptosis related proteins on malignant transformation of ovarian tumors: A comparison between Bcl-2/Bax ratio and p53 immunoreactivity.

In this study, we compared the immunoreactivities of Bcl-2, Bax and p53 proteins in ovarian tumors and related the immunohistochemical findings to the histological type of the tumors. Formalin-fixed, paraffin wax-embedded tissue sections from 40 patients who had serous-mucinous borderline tumors and serous-mucinous adenocarcinoma of the ovary (n=10 each) were stained with hematoxylin-eosin (H&E). After histopathological examination, serial sections were stained immunohistochemically with primary antibodies to Bcl-2, Bax and p53 using an avidin-biotin-peroxidase method. A semi-quantitative grading system was used to compare the immunohistochemical staining intensities. The nuclear DNA fragmentation of apoptosis was determined using TUNEL method. As a result of immunohistochemical staining, increased immunoreactivity of Bcl-2 was observed in adenocarcinomas when compared to borderline tumors (P<0.001). Strong immunoreactivity of Bcl-2 and mild immunoreactivities of Bax and p53 were detected in ovarian adenocarcinomas. There were no significant statistical differences in the immunoreactivity of Bax among the histological type of ovarian tumors. Whereas a balance was observed between the immunoreactivities of Bcl-2 and Bax in the borderline cases, and this balance was strongly changed toward the anti-apoptotic Bcl-2 protein in patients with adenocarcinoma. TUNEL staining of sections indicated apoptotic cells in the serous borderline tumors were about 8-fold higher than in the serous adenocarcinoma. The results of this study on apoptosis-related factors might help to develop novel protective and therapeutic approaches, such as isoflavonoids and isothiocyanates, which were associated with decreased Bcl-2/Bax ratio, against the malignant epithelial ovarian tumors.

A physical model of the thermodilution method: influences of the variations of experimental setup on the accuracy of flow rate estimation.

The thermodilution method has been widely used to estimate cardiac output by injecting a cold solution into circulating blood. It is uncertain if radial heat transfer from the vascular/cardiac wall to circulating injectate can cause inaccurate results with this method. In this study, we have introduced a physical experimental model of the thermodilution method without recirculation of the cold solution. To test the accuracy of the thermodilution method, the experimental setup included an aluminum tube to allow radial heat transfer. Variations of the following parameters were conducted: (i) the real flow rate, (ii) the distance between injection point of cold solution and the temperature sensor, (iii) the volume of injectate, and (iv) the temperature of injectate. By following the above variations, we have calculated different correction factors eliminating the influence of radial heat transfer on the estimation of flow rate by the thermodilution method. The results indicate that changes in both injectate temperature and volume have no influence on the estimation of flow rates. The experimental variations, which can cause greater radial heat transfer, seem to be responsible for the result of the smaller estimation of the flow rate than the real value. These variations include (i) a decreased real flow rate and (ii) increased distances between the injection point of cold fluid and the thermosensor. Such an incorrect estimation could be eliminated by using correction factors. The correction factor seems to be a function of the area of the thermodilution curve, assuming no recirculation.

Significance of tyrosine kinase activity on malign transformation of ovarian tumors: a comparison between EGF-R and TGF-alpha.

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are members of the polypeptide growth factor family. The epidermal growth factor-receptor (EGF-R) is a receptor tyrosine kinase of the ErbB family. Many types of cancer, including ovarian cancer, display enhanced EGF-R immunoreactivity on their cell surface membranes. Also, an increase in TGF-alpha synthesis and secretion usually occurs in human carcinoma cell lines. In this study, we compared the immunoreactivities of TGF-alpha and EGF-R in ovarian tumors and related immunohistochemical findings to the histological type of the tumors. Formalin-fixed, paraffin wax-embedded tissue sections from 40 patients who had serous-mucinous borderline tumor and serous-mucinous adenocarcinoma of the ovary (n=10 each) were stained with hematoxylin-eosin and labeled for binding of primary antibodies against TGF-alpha and EGF-R using an avidin-biotin-peroxidase method. A semi-quantitative grading system was used to compare immunohistochemical labeling intensities. Increased immunoreactivity of EGF-R and moderate immunoreactivity of TGF-alpha was detected in adenocarcinomas. There was no significant difference in the immunoreactivity of TGF-alpha among the histologic types of ovarian tumors. The results of this study support the hypothesis that EGF-R may be a more useful marker than TGF-alpha in epithelial ovarian tumors.

Sensitively recorded breathing signals of rats and their nonlinear dynamics.

Nonlinear dynamical properties of sensitively recorded breathing signals (SRBS), which include cardiac induced air flow pulsations so-called pneumocardiogram (PNCG) signals, are investigated, in this methodological study. For this purpose, we assessed the SRBS of laboratory rat. The nonlinear behaviors of SRBS were investigated by the reconstructing phase space, using the autocorrelation function and the false nearest neighbor method. The chaotic SRBS attractors were discussed from the point of view of the cardiopulmonary system. This method can be used to assess the heart performance and respiratory mechanics, and might be useful to design for the physiological studies of cardiorespiratory system in small laboratory animals.