Search Results

1 - 10 of 11 items

  • Author: Mariusz Kozakiewicz x
Clear All Modify Search

Abstract

Any stay in an environment with an increased oxygen content (a higher oxygen partial pressure, pO2) and an increased pressure (hyperbaric conditions) leads to an intensification of oxidative stress. Reactive oxygen species (ROS) damage the molecules of proteins, nucleic acids, cause lipid oxidation and are engaged in the development of numerous diseases, including diseases of the circulatory system, neurodegenerative diseases, etc. There are certain mechanisms of protection against unfavourable effects of oxidative stress. Enzymatic and non-enzymatic systems belong to them. The latter include, among others, heat shock proteins (HSP). Their precise role and mechanism of action have been a subject of intensive research conducted in recent years. Hyperoxia and hyperbaria also have an effect on the expression and activity of nitrogen oxide synthase (NOS). Its product - nitrogen oxide (NO) can react with reactive oxygen species and contribute to the development of nitrosative stress. NOS occurs as isoforms in various tissues and exhibit different reactions to the discussed factors. The authors have prepared a brief review of research determining the effect of hyperoxia and hyperbaria on HSP expression and NOS activity.

Abstract

The analysis of Berezin and Kiselev’s concept assuming linear association of molecules in a localised adsorption monolayer on the homogeneous surface of a solid adsorbent was carried out. An inconsistency due to the lack of consideration of equilibrium concentration of free adsorption sites in the formulation of the expression for the association constant has been pointed out. It was shown that the correct form of this function leads to the final adsorption equation being identical to the specific case of the Fowler-Guggenheim equation. The obtained result has been generalised to cases of branched adsorbateadsorbate associations. A new adsorption equation limiting the association to at most the dimers has been introduced. Critical conditions for the two-dimensional condensation of the adsorption layer were determined. By applying the formalism of canonical ensemble, full equivalence of the phenomenological and statistical methods was demonstrated in the description of the intermolecular interactions in the localised adsorption monolayer.

Abstract

Diabetes is an “epidemic of the 21st century” and it is estimated that in 2011 6.7% of Poland’s population suffered from diabetes, one quarter of which was unaware of the disease. Such a high prevalence of diabetes mellitus results in an increasing number of physicians being confronted with the problem of qualifying patient with diabetes to partake in amateur sports, including diving. This publication presents the most important information concerning risk assessment, admission of diabetic patients to amateur diving and some proposed protocols of management before and during sport practice.

Abstract

Continuing the discussion on the description of adsorbate-adsorbate association on homogeneous surfaces of solids, an attempt was made to formulate an analytical form of adsorption equation for a multilayer adsorption phase. The validity of Berezin’s and Kiselev’s assumptions concerning the independence of adsorption in further layers from the model of the phenomenon in the first of them was discussed. The fundamental validity of this assumption has been demonstrated, simultaneously ridding it of its arbitrary character. The main aim of the study was to demonstrate the possibility of formulating a description assuming molecule association in the entire adsorption phase (and not only in the first layer). Theoretical considerations are confined to the case of dimerisation in the concentration range thus warranting the approximation characteristic of the Berezin and Kiselev model. The obtained final adsorption equation exhibits physically acceptable boundary properties; with adequate assumptions it amounts to the Brunauer, Emmett and Teller equation, the equation formulated earlier by one of the authors of this paper or the Langmuir equation.

Abstract

This paper characterises the concept of monolayer mobile gas adsorption on a homogeneous surface of a solid. The theoretical basis of the phenomenological variant of the description of adsorption equilibrium in the system in question are discussed. The essential features of the solutions to date are discussed, and the effect of the free surface of adsorbent on the form of the final adsorption equation is stressed.

An alternative concept of the free surface based on the modified two-dimensional analogue of Reiss, Frisch and Lebowitz equations is also presented. The obtained adsorption equation was tested for critical parameters of two-dimensional condensation of the adsorption layer, and then used to describe the experimental data available in literature. The verification carried out confirmed the correctness and usefulness of the proposed concept.

Abstract

This article is related thematically to two of our earlier publications, which demonstrated full equivalence of statistical and phenomenological methods in the description of physical gas adsorption on the surface of a solid body, and the fundamental possibility of analytical solution of adsorbate-adsorbate association problems in the entire multi-layer adsorption phase. The quasi-chemical scheme of secondary interactions leading to the formation of horizontal multimolecular adsorption complexes has been elaborated. A new adsorption equation was formulated taking into account the dimerisation of adsorbed molecules in the whole adsorption phase, as well as the influence of topography of the binding sites of adsorbent surfaces on the form of this solution.

Abstract

The aim of this study was to analyse dynamic fluctuations in the circadian rhythm of the core body temperature in healthy adults exposed to conditions in a hyperbaric chamber, using fully objective-telemetric measurement methods. The study group consisted of 13 healthy males (age 32±6.4 years, height 1.85±0.1 m, body weight 84.00±6.3 kg; BMI 24.7±1.2 kg/m2). The core body temperature (CBT) was measured with the Vital Sense telemetry system. The volunteers were placed in a hyperbaric chamber, exposed to compression of 400 kPa, with the exposure plateau of approx. 30 minutes, followed by gradual decompression. The mean core temperature was 36.71°C when registered within 10 minutes before the exposure, 37.20°C during the exposure, 37.27°C one hour after the exposure, 37.36°C 2 hours after the exposure, and 37.42°C three hours after the exposure. The conducted observations show that one-hour stay in a hyperbaric chamber at a depth of 30 m results in an increase in the body temperature, particularly significant after the exposure ends, and maintained for at least 3 hours after the exposure.

Abstract

Hyperbaric oxygen therapy (HBOT) is found among the interests of researchers who seek new methods of treatment of diseases of the nervous system. An increase of the partial pressure of oxygen in arterial blood within the appropriate range leads to numerous changes in the cells of the brain tissue. In this paper we analyse the results of selected articles describing HBOT used on pathologies of the nervous system such as stroke, autism, multiple sclerosis and cerebral palsy as well as in the course of research on animal models. The results are promising, although some studies struggled with numerous methodological problems and differences in the applied protocols, which resulted in conflicting results in individual interventions. In consequence, the need for further studies in randomised control trials and determination of the protocol by an international group of researchers dedicated to the use of HBOT was emphasised.

Abstract

Changes observed in the core body temperature of divers are the result of a multifaceted response from the body to the change of the external environment. In response to repeated activities, there may be a chronic, physiological adaptation of the body’s response system. This is observed in the physiology of experienced divers while diving. The purpose of this study is to determine the immediate and delayed effects of hyperbaric exposure on core temperature, as well as its circadian changes in a group of three experienced divers. During compression at 30 and 60 meters, deep body temperature values tended to increase. Subsequently, deep body temperature values showed a tendency to decrease during decompression. All differences in core temperature values obtained by the group of divers at individual time points in this study were not statistically significant.

Abstract

Introduction Among experienced divers, dive adaptation is seen as a modified pattern of physiological changes. This is reflected, inter alia, in the change in cardiovascular responses, therefore there is need to examine the role of the autonomic nervous system in cardiovascular response modulation after hyperbaric exposure. Material and methods Ten experienced divers took part in the study. The effects of hyperbaric exposure at 30 and 60 meters and interaction (depth x time) were measured. Changes in HR, RRI, CI and HRV values have been taken into analysis. Results Hyperbaric exposure at 30 meters significantly affected HFnu-RRI elevation and decrease of LFnu-RRI (F = 42.92, p <0.00001), without significant affecting the HR, RRI and CI. Exposure to hyperbaric 60 m increased HR and CI (F = 7.64, p = 0.01 and F = 4.89, p = 0.04 respectively) and RRI (F = 7.69, p = 0.01), without significant impact on other variables. The influence of interaction (depth x time) was significant in all measured variables. Conclusions The results indicate that hyperbaric exposure at 60 meters affected HR, RRI, CI parameters, that were not significantly affected by hyperbaric exposure at 30 meters. On the other hand, the exposure at 30 meters showed a significant effect on the LFnu and HFnu HRV, which were not significantly affected by the exposure at 60 meters. Significant effect of time and depth interaction in each of the analyzed variables was observed.