Monitoring of water content and water distribution in ischemic hearts

Therapy of pancreatic cancer with alternating electric fields: Limitations of the method

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with a poor prognosis. More effective treatment options are urgently needed. The use of physical and weak alternating electric fields (TTFields) can inhibit cell division of PDAC carcinoma and is currently being investigated in clinical trials. Here, we analyzed this new physical treatment under non-ideal conditions such as may occur during patient treatment. Three established human PDAC cell lines BxPC-3, gemcitabine-resistant BxPC-3 (BxGem), AsPC-1, and a non-malignant primary pancreatic cell line CRL-4023 were treated with TTFields in vitro. MTT assays, electrical impedance measurement, cell staining with Annexin V/7AAD followed by FACS analysis, digital image analysis and immunohistochemistry were performed. Treatment with TTFields smaller than 0.7 V/cm and field lines in the direction of mitotic spindle orientation significantly inhibited proliferation of all PDAC cells at 150 kHz, but significantly increased viability of AsPC-1 cells at all frequencies between 100 kHz and 300 kHz and that of BxPC-3 and BxGem cells at 250 kHz. Apoptosis or necrosis were not induced. Non-malignant CRL-4023 cells were not affected at 150 kHz. TTFields damaged PDAC cell lines but even favored their viability at very weak field strength and unfavorable frequency or inadequate field direction.

Hearts during ischemia with or without HTK-protection analysed by dielectric spectroscopy

OBJECTIVE

We investigated canine hearts during ischemia after aortic cross clamping (UI, n  =  20) and after HTK-cardioplegia (HTK, n  =  24) at 35 °C, 25 °C, 15 °C, and 5 °C with the aim to compare tissue changes caused by the activity of anaerobic metabolism(AAM), cell membrane destruction(CD), and gap junction uncoupling(GJU).

APPROACH

We measured continuously the complex dielectric spectrum(DS), ATP- and lactate content, extracellular pH, and rigor contracture. To identify changes in DS caused by AAM, CD, and GJU we performed additional experiments on the gap junction-free skeletal muscle. We used heart model simulations to calculate the effect of temperature.

MAIN RESULTS

AAM affected the DS at 10 MHz and we found a strong correlation between DS and the proton concentration with a maximum of DS at 10 mmol g^-1 dry weight in ATP-concentration. The time of GJU was detected by a characteristic increase in DS and CD by a characteristic decrease at 13 kHz. In comparison to UI, GJU, AAM and CD were delayed by HTK and by hypothermia, indicating a minimization of energy consumption and an improved preservation of tissue structure.

SIGNIFICANCE

The novel findings were that in UI at 5 °C GJU occurred earlier and AAM remained constant, indicating a less effective preservation in UI by deep hypothermia in contrast to HTK.

Dielectric properties of human ovary follicular fluid at 9.2 GHz

The influence of the follicle size, rapid freezing to -196 degrees capital ES, Cyrillic and cryopreservation in liquid nitrogen within a period of one month of the human ovary follicular fluid (FF) on its dielectric properties is studied by the microwave dielectric method. The FF was obtained from dominant follicles of patients who received treatment for infertility by extracorporal fertilization. We have measured the real part (epsilon') of the complex permittivity of the native and frozen follicular fluids at the room temperature. A resonator type ultra high frequency (UHF) dielectrometer at the frequency of 9.2 GHz has been used. We have also obtained the values of the total protein, hormones and glucose concentration in the FF. It was found that rapid freezing reduces epsilon' of the FF. It can result from the bound water increase in the system. It was also found the rise in permittivity and the total protein concentration with the increase of a follicle size, which could be explained by protein dehydration as a result of its clustering and aggregation.

Monitoring of Lung Edema by Microwave Reflectometry during Lung Ischemia-Reperfusion Injury in vivo

It is still unclear whether lung edema can be monitored by microwave reflectometry and whether the measured changes in lung dry matter content (DMC) are accompanied by changes in PaO2 and in pro- to anti-inflammatory cytokine expression (IFN-gamma and IL-10). Right rat lung hili were cross-clamped at 37 degrees C for 0, 60, 90 or 120 min ischemia followed by 120 min reperfusion. After 90 min (DMC: 15.9 +/- 1.4%; PaO2: 76.7 +/- 18 mm Hg) and 120 min ischemia (DMC: 12.8 +/- 0.6%; PaO2: 43 +/- 7 mm Hg), a significant decrease in DMC and PaO2 throughout reperfusion compared to 0 min ischemia (DMC: 19.5 +/- 1.11%; PaO2: 247 +/- 33 mm Hg; p < 0.05) was observed. DMC and PaO2 decreased after 60 min ischemia but recovered during reperfusion (DMC: 18.5 +/- 2.4%; PaO2: 173 +/- 30 mm Hg). DMC values reflected changes on the physiological and molecular level. In conclusion, lung edema monitoring by microwave reflectometry might become a tool for the thoracic surgeon.

Monitoring water content of rat lung tissuein vivo using microwave reflectometry

Measurement of lung water is an important diagnostic means of assessing pulmonary oedema. Water content affects the dielectric spectrum at microwave frequencies, but quantification is still a problem. A new lung tissue model is presented that allows the calculation of water content from dielectric permittivity. The dielectric permittivity of lung tissue was measured by microwave reflectometry using a non-invasive surface probe. During perfusion of rat lungs (n = 22) with blood, injury was induced by interruption of the blood supply for a duration between 0 (control) and 2 h. Water content was assessed from dielectric permittivity using a new mixture formula and was also determined by drying and weighing. The mixture formula allows for the dielectric polarisation of water, dry matter and air in the tissue. A linear correlation was found between total water content determined from dielectric permittivity and that from drying and weighing (y= 1.001x, R2 = 0.8). Lung injury showed an increase in total water content from 80.9 +/- 1.2% (control) to 84.1 +/- 0.9% (p < 0.01). The analysis of dielectric permittivity data at microwave frequencies with the new tissue model is sensitive enough to detect water accumulation produced by lung injury and it can be used to monitor total water content without tissue destruction.