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Bożena Kuraszkiewicz and Maria Piotrkiewicz

A review of concepts regarding the origin of respiratory muscle fatigue

In this review, the classification of respiratory muscle fatigue from the perspective of its origin is presented. The fatigue is classified as central or peripheral, and the latter further subdivided into high- and low-frequency fatigue. However, muscle fatigue is a complex process and all three types of fatigue probably occur simultaneously in the overloaded respiratory muscles. The relative importance of each type depends on the duration of respiratory loading and other physiological variables. However, central and high-frequency fatigue resolve rapidly once muscle overload is removed, whereas low-frequency fatigue persists over long time.

Open access

Waclawa Marcoin, Henryk Duda and Dariusz Chrobak

Properties of solid dispersions of selected magnesium salts and the absorption process of Mg2+ 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.

Open access

Dariusz Wojciechowski, Piotr Sionek, Kazimierz Peczalski and Dariusz Janusek

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.

Open access

Rahul Umbarkar, Sanjay Supe, Manoy Pandey and Jayanty Ashok

Physical characteristics of photon beam from a CLINAC-DBX single energy accelerator

Commissioning beam data are treated as a reference and ultimately used by treatment planning systems, therefore, it is vitally important that the collected data are of the highest quality, in order to avoid dosimetric and patient treatment errors that may subsequently lead to a poor radiation outcome. High-energy photon and electron beams from different accelerators of the same nominal energy may have different dosimetric characteristics due to differences in target and flattening filter materials, accelerator guide and collimator designs. In the present study, clinically pertinent data for the available photon energy were investigated. For making measurements in water, first time in India, a three dimensional radiation field analyzer RFA (CRS- Scan -O-Plan) was used. For absolute dosimetry and other measurements like relative output factors, wedge factors etc., a DOSE1 electrometer (Scanditronix Wellhofer) in a white polystyrene was employed. All the measured data were utilized as an input to the ECLIPSE treatment planning system for further clinical use.

Open access

Mieczysław Zielczyński, Natalia Golnik and Michał Gryziński

Sposób wyznaczania przestrzennego współczynnika jakości neutronów prędkich w polach promienowania mieszanego wykorzystujacy zaawansowane metody rekombinacyjne

Przedstawiono sposób wyznaczania przestrzennego współczynnika jakości neutronów prędkich, Qn *(10), w polu promieniowania mieszanego o nieznanym, lecz ograniczonym, widmie energii neutronów. W tym sposobie wykorzystuje się korelacje między wartościami Qn *(10), obliczonymi metodą Monte Carlo dla neutronów monoenergetycznych, a parametrami doświadczalnych charakterystyk nasycenia komory rekombinacyjnej, umieszczonej we wzorcowych polach neutronów monoenergetycznych wraz z towarzyszącym promieniowaniem gamma. Omija się przy tym szereg niepewności, związanych z brakiem pełnej odpowiedniości między współczynnikiem jakości promieniowania a parametrami, od których zależy lokalna rekombinacja jonów, a także z brakiem pełnej odpowiedniości konstrukcji komory rekombinacyjnej z tzw. kulą MKJR (ang. ICRU) definiującą wielkości operacyjne H*(10) i Q*(10).

Open access

Murugan Appasamy, Sidonia Xavier, Thayalan Kuppusamy and Ramasubramanian Velayudham

Measurement of Head Scatter Factor for Linear Accelerators using Indigenously Designed Columnar Mini Phantom

A columnar mini phantom is designed as recommended by ESTRO to measure the Head Scatter Factor (Sc) for 6 MV beam of two linear accelerators. The measurement of Sc at different orientations of the chamber, parallel and perpendicular at 1.5 cm depth predicts the deviation of 2.05% and 1.9% for Elekta and Siemens linear accelerators respectively. The measurement of Sc at 1.5 cm is higher compared to 10 cm depth for both the linear accelerators suggesting the electron contamination at 1.5 cm depth. The effect of wedges on Sc yields a significant contribution of 3.5% and 5% for Siemens and Elekta linear accelerators respectively. The collimator exchange effect reveals the opening of upper jaw increases the Sc irrespective of the linear accelerator. The result emphasizes the need of Sc measurement at 10 cm. The presence of wedge influences the Sc value and the SSD has no influence on Sc. The measured Sc values are in good agreement with the published data.

Open access

Natalia Golnik and Piotr Tulik

IRPA initiative on radiation protection culture

The concept of radiation protection culture, proposed by French Society for Radiation Protection (SFRP) and then launched by International Radiation Protection Association (IRPA) is presented. The paper is focused on the role of radiation culture in preventing unjustified fear associated with the use of radiation. Principles of RP culture and optimization of radiation protection, as well as the problems how RP culture can be learned and how to engage the stakeholders are considered.

Open access

Anna Cabaj and Wojciech Zmyslowski

Identification of the effects of peripheral nerves injury on the muscle control - A review

Impairment of motor function following peripheral nerve injury is a serious clinical problem. Generally nerve injury leads to erroneous control of muscle activity that results in gait and voluntary movement abnormalities followed by muscle atrophy. This article presents a review of studies on the effects of peripheral nerve injury on the motor system performed on animal models. We focused our attention on the results that are fundamental for better understanding of the degenerative and regenerative processes induced by nerve injury as well as of the mechanisms of structural changes in neuronal networks controlling movement. Quoted results are also important for clinical applications because they allow to develop new diagnostic and therapeutic techniques that can be used after nerve injury inducing motor deficits. However, till now no efficient therapy inducing satisfactory recovery was found. There is still a need to continue an advanced basic research directed to develop effective therapies. Thus the aim of this review is to compare the results of recent studies performed on various animal models in order to propose new methods for identification of mechanisms responsible for muscle deficits and propose targets for new pharmacological therapies.

Open access

Elzbieta Olejarczyk, Maciej Kaminski, Radoslaw Marciniak, Tomasz Byrczek, Michal Stasiowski, Przemyslaw Jalowiecki, Aleksander Sobieszek and Wojciech Zmyslowski

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.

Open access

Tomasz Pliszczyński, Jakub Ośko, Katarzyna Ciszewska, Zbigniew Haratym, Marianna Umaniec and Renata Sosnowiec

Ocena narażenia wewnętrznego za pomocą licznika promieniowania ciała człowieka

Proces oceny narażenia wewnętrznego na skażenia substancjami promieniotwórczymi jest skomplikowany i towarzyszy mu wiele czynników, które są źródłem niepewności szacowania obciążającej dawki efektywnej. W niniejszym artykule przedstawiono sposób właściwego postępowania podczas szacowania obciążającej dawki efektywnej za pomocą Licznika Promieniowania Ciała Człowieka.