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Journal Details
Format
Journal
eISSN
1898-0309
First Published
30 Dec 2008
Publication timeframe
4 times per year
Languages
English

Search

Volume 17 (2011): Issue 2 (June 2011)

Journal Details
Format
Journal
eISSN
1898-0309
First Published
30 Dec 2008
Publication timeframe
4 times per year
Languages
English

Search

5 Articles
Open Access

Properties of solid dispersions of selected magnesium salts and the absorption process of Mg2+ ions in vitro

Published Online: 15 Feb 2012
Page range: 55 - 67

Abstract

Properties of solid dispersions of selected magnesium salts and the absorption process of Mg<sup>2+</sup> ions in vitro

The paper presents an application of phosphatidylcholine 45% (PC 45) and polyvinylpyrrolidone (PVP) in formulations of magnesium salts such as Mg(VitB6) and Mg(VitB6Arg) prepared by solid dispersion (SD) techniques. The evaluation of influence of the selected carriers on some physicochemical properties of solid dispersions and on the absorption process of Mg +2 ions in vitro were made. An infrared (IR) spectra study suggested creation of a hydrogen bond between the carriers and the examined magnesium salts. The results of the following thermal analysis: differential thermal analysis (DTA), thermogravimetry (TG), and differential scanning calorimetry (DSC) showed that application of PVP into SD lower the temperature of the decomposition process. However, in the case of PC 45 into SD the characteristic thermal effects of higher temperatures were observed. Moreover, values of the enthalpy SD of decomposition process were decreased. The results of these studies on absorption process of Mg2+ ions in vitro showed the positive influence of the applied carriers on the partition coefficient values (log P) in the examined formulation.

Keywords

  • Vitamin B6
  • Arginine
  • Polyvinylopirrolidone
  • Phosphatidylcholine
  • Small intestine
Open Access

Plethyzmography in assessment of hemodynamic results of pacemaker functions programming

Published Online: 15 Feb 2012
Page range: 69 - 73

Abstract

Plethyzmography in assessment of hemodynamic results of pacemaker functions programming

The paper presents potential role of plethyzmography in optimization of heart hemodynamic function during pacemaker programming.

The assessment of optimal stroke volume in patients, with implanted dual chamber pacemaker (DDD), by plethyzmography was a goal of the study. The data were collected during pacing rhythm. 20 patients (8 female and 12 male, average 77.4+/-4.6 years) with dual chamber pacemaker (DDD) and with pacing rhythm during routine pacemaker control and study tests were incorporated in the study group. Hemodynamic parameters were assessed during modification of atrio-ventricular delay (AVD) for pacing rhythm of 70 bpm and 90 bpm. The time of atrioventricular was programmed with 20 ms steps within range 100-200 ms and data were recorded with two minutes delay between two consecutive measurements. Stroke volume (SV) and cardiac output (CO) were calculated from plethyzmographic signal by using Beatscope software (TNO Holand). Highest SV calculated for given pacing rhythm was named optimal stroke volume (OSV) and consequently highest cardiac output was named maximal cardiac output (MCO). The time of atrio-ventricular delay for OSV was named optimal atrioventricular delay (OAVD).

The results have showed: mean values of OAVD for 70 bpm - 152+/-33 ms and for 90 bpm -149+/-35 ms, shortening of the mean OAVD time caused by increase of pacing rate from 70 bpm to 90 bpm what resulted in statistically significant decrease of OSV with not statistically significant increase of MCO. The analysis of consecutive patients revealed three types of response to increase of pacing rhythm: 1. typical-shortening of OAVD, 2. neutral-no change of OAVD and 3.atypical-lengthening of OAVD.

Keywords

  • plethyzmography
  • atrio -ventricular delay
  • stroke volume
  • cardiac output
  • pacemaker
Open Access

Dosimetric comparison of three dimensional conformal radiotherapy and intensity modulated radiotherapy in high grade gliomas

Published Online: 15 Feb 2012
Page range: 75 - 84

Abstract

Dosimetric comparison of three dimensional conformal radiotherapy and intensity modulated radiotherapy in high grade gliomas

Treatment of high-grade gliomas continues to be frustrating for the clinician as the medial survival stands at a dismal 14.5 months for glioblastoma multiforme (GBM) with the current standard of care. Given the high dose and generous margins required to be irradiated, three dimensional conformal radiotherapy (3DCRT) has become standard practice. Radiation dose escalation beyond 60 Gy, by means of stereotactic or intensity modulated radiotherapy (IMRT) boost, has not yielded clinically significant benefits in terms of local control or survival. At the same time, the potential of IMRT to spare normal tissues such as the brain stem and the optic apparatus makes it an attractive tool for modern radiation oncologists in seeking to improve post-radiotherapy quality of life. At our centre, we have been treating a large number of cases of high grade glioma with 3DCRT and IMRT for the last several years. The present study has been an effort to understand any potential benefits that IMRT, even without dose escalation, can offer.

Open Access

Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

Published Online: 15 Feb 2012
Page range: 85 - 94

Abstract

Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

Paramagnetic centers in DOPA-melanin and complexes of DOPA-melanin with netilmicin and Cu(II) were studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Measurements of continuous microwave saturation of EPR spectra at temperatures: 125 K, 175 K, 225 K, 275 K, were performed. Homogeneous broadening of all the examined EPR spectra was observed. EPR spectra of DOPA-melanin-Cu(II) complexes saturated at higher microwave powers than the others tested melanin samples. Fast spin-lattice relaxation exists in DOPA-melanin-Cu(II) complexes. Slow spin-lattice relaxation processes exist in melanin's paramagnetic centers of DOPA-melanin and its complexes with netilmicin, and its complexes with both netilimicin and Cu(II). EPR spectra of all the tested samples saturated at higher microwave powers with increasing of the measuring temperature. Faster spin-lattice relaxation processes occurs in DOPA-melanin and its complexes with netilmicin and Cu(II) at higher temperature.

Keywords

  • paramagnetic centers
  • DOPA-melanin
  • netilmicin
  • microwave saturation
  • EPR spectroscopy
Open Access

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

Published Online: 15 Feb 2012
Page range: 95 - 104

Abstract

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

The aim of this study was to estimate spectral properties and propagation of the EEG signals registered during sevoflurane anaesthesia between individual EEG recording channels. The intensities of activity flows were calculated for delta, theta, alpha and beta waves using the Directed Transfer Function integration procedure. It was found that delta waves played the dominant role in the EEG signal propagation during anesthesia and it was suggested that theta and alpha waves propagation could be related to the processes participating in the wakefulness control. Data obtained with DTF method were compared with data received from the analysis of cerebral blood flow with the use of PET in other laboratory. This study showed that analysis of the EEG signal propagation is useful for better understanding and thus safer induction of anaesthesia procedure.

Keywords

  • EEG signal
  • volatile anaesthesia
  • fluorinated inhalation anaesthetics
  • sevoflurane
  • Directed Transfer Function method
5 Articles
Open Access

Properties of solid dispersions of selected magnesium salts and the absorption process of Mg2+ ions in vitro

Published Online: 15 Feb 2012
Page range: 55 - 67

Abstract

Properties of solid dispersions of selected magnesium salts and the absorption process of Mg<sup>2+</sup> ions in vitro

The paper presents an application of phosphatidylcholine 45% (PC 45) and polyvinylpyrrolidone (PVP) in formulations of magnesium salts such as Mg(VitB6) and Mg(VitB6Arg) prepared by solid dispersion (SD) techniques. The evaluation of influence of the selected carriers on some physicochemical properties of solid dispersions and on the absorption process of Mg +2 ions in vitro were made. An infrared (IR) spectra study suggested creation of a hydrogen bond between the carriers and the examined magnesium salts. The results of the following thermal analysis: differential thermal analysis (DTA), thermogravimetry (TG), and differential scanning calorimetry (DSC) showed that application of PVP into SD lower the temperature of the decomposition process. However, in the case of PC 45 into SD the characteristic thermal effects of higher temperatures were observed. Moreover, values of the enthalpy SD of decomposition process were decreased. The results of these studies on absorption process of Mg2+ ions in vitro showed the positive influence of the applied carriers on the partition coefficient values (log P) in the examined formulation.

Keywords

  • Vitamin B6
  • Arginine
  • Polyvinylopirrolidone
  • Phosphatidylcholine
  • Small intestine
Open Access

Plethyzmography in assessment of hemodynamic results of pacemaker functions programming

Published Online: 15 Feb 2012
Page range: 69 - 73

Abstract

Plethyzmography in assessment of hemodynamic results of pacemaker functions programming

The paper presents potential role of plethyzmography in optimization of heart hemodynamic function during pacemaker programming.

The assessment of optimal stroke volume in patients, with implanted dual chamber pacemaker (DDD), by plethyzmography was a goal of the study. The data were collected during pacing rhythm. 20 patients (8 female and 12 male, average 77.4+/-4.6 years) with dual chamber pacemaker (DDD) and with pacing rhythm during routine pacemaker control and study tests were incorporated in the study group. Hemodynamic parameters were assessed during modification of atrio-ventricular delay (AVD) for pacing rhythm of 70 bpm and 90 bpm. The time of atrioventricular was programmed with 20 ms steps within range 100-200 ms and data were recorded with two minutes delay between two consecutive measurements. Stroke volume (SV) and cardiac output (CO) were calculated from plethyzmographic signal by using Beatscope software (TNO Holand). Highest SV calculated for given pacing rhythm was named optimal stroke volume (OSV) and consequently highest cardiac output was named maximal cardiac output (MCO). The time of atrio-ventricular delay for OSV was named optimal atrioventricular delay (OAVD).

The results have showed: mean values of OAVD for 70 bpm - 152+/-33 ms and for 90 bpm -149+/-35 ms, shortening of the mean OAVD time caused by increase of pacing rate from 70 bpm to 90 bpm what resulted in statistically significant decrease of OSV with not statistically significant increase of MCO. The analysis of consecutive patients revealed three types of response to increase of pacing rhythm: 1. typical-shortening of OAVD, 2. neutral-no change of OAVD and 3.atypical-lengthening of OAVD.

Keywords

  • plethyzmography
  • atrio -ventricular delay
  • stroke volume
  • cardiac output
  • pacemaker
Open Access

Dosimetric comparison of three dimensional conformal radiotherapy and intensity modulated radiotherapy in high grade gliomas

Published Online: 15 Feb 2012
Page range: 75 - 84

Abstract

Dosimetric comparison of three dimensional conformal radiotherapy and intensity modulated radiotherapy in high grade gliomas

Treatment of high-grade gliomas continues to be frustrating for the clinician as the medial survival stands at a dismal 14.5 months for glioblastoma multiforme (GBM) with the current standard of care. Given the high dose and generous margins required to be irradiated, three dimensional conformal radiotherapy (3DCRT) has become standard practice. Radiation dose escalation beyond 60 Gy, by means of stereotactic or intensity modulated radiotherapy (IMRT) boost, has not yielded clinically significant benefits in terms of local control or survival. At the same time, the potential of IMRT to spare normal tissues such as the brain stem and the optic apparatus makes it an attractive tool for modern radiation oncologists in seeking to improve post-radiotherapy quality of life. At our centre, we have been treating a large number of cases of high grade glioma with 3DCRT and IMRT for the last several years. The present study has been an effort to understand any potential benefits that IMRT, even without dose escalation, can offer.

Open Access

Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

Published Online: 15 Feb 2012
Page range: 85 - 94

Abstract

Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

Paramagnetic centers in DOPA-melanin and complexes of DOPA-melanin with netilmicin and Cu(II) were studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Measurements of continuous microwave saturation of EPR spectra at temperatures: 125 K, 175 K, 225 K, 275 K, were performed. Homogeneous broadening of all the examined EPR spectra was observed. EPR spectra of DOPA-melanin-Cu(II) complexes saturated at higher microwave powers than the others tested melanin samples. Fast spin-lattice relaxation exists in DOPA-melanin-Cu(II) complexes. Slow spin-lattice relaxation processes exist in melanin's paramagnetic centers of DOPA-melanin and its complexes with netilmicin, and its complexes with both netilimicin and Cu(II). EPR spectra of all the tested samples saturated at higher microwave powers with increasing of the measuring temperature. Faster spin-lattice relaxation processes occurs in DOPA-melanin and its complexes with netilmicin and Cu(II) at higher temperature.

Keywords

  • paramagnetic centers
  • DOPA-melanin
  • netilmicin
  • microwave saturation
  • EPR spectroscopy
Open Access

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

Published Online: 15 Feb 2012
Page range: 95 - 104

Abstract

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

The aim of this study was to estimate spectral properties and propagation of the EEG signals registered during sevoflurane anaesthesia between individual EEG recording channels. The intensities of activity flows were calculated for delta, theta, alpha and beta waves using the Directed Transfer Function integration procedure. It was found that delta waves played the dominant role in the EEG signal propagation during anesthesia and it was suggested that theta and alpha waves propagation could be related to the processes participating in the wakefulness control. Data obtained with DTF method were compared with data received from the analysis of cerebral blood flow with the use of PET in other laboratory. This study showed that analysis of the EEG signal propagation is useful for better understanding and thus safer induction of anaesthesia procedure.

Keywords

  • EEG signal
  • volatile anaesthesia
  • fluorinated inhalation anaesthetics
  • sevoflurane
  • Directed Transfer Function method

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