Wyniki wyszukiwania - Biblioteka Nauki

1

Simplifying assumptions and the scope of application of lipid membrane models

100%

Kubica K.

|

2011

|

tom Vol. 7, no. 2

13--16

EN

Biological membranes are components of the cell – the basic unit of life. Their structure originates from amphiphilic properties of lipid molecules ( the major constituent of biological membranes) which when surrounded by water spontaneously form organized structures that include bilayers. A bilayer created purely out of lipid molecules is used as a physical model of biological membranes on which one can study biological processes associated with their lipid phase. These may include: passive transport, formation and decomposition of domains, phase transitions and formation of pores influenced by an external electric field. Experiments on lipid bilayer coupled with studies of its mathematical models enable to gain an understanding of the aforementioned biological membrane phenomena at a molecular level. A mathematical model is characterized by a set of simplifying assumptions which determines its application. By developing a simple model that only takes into account the structure of the hydrophobic lipid molecules, we were able to observe phases of various density corresponding to temperature changes. Expanding the model by including the polar parts of lipid molecules expressed via a surface pressure multiplied by a surface area per one molecule increased its range of research. This assumption, did not allow capturing some of the factors such as ionic strength or a presence of water molecules. Supplementing the model with new assumptions increased its application. The extended model allowed additionally tracking changes in the membrane influenced by biologically active amphiphilic compounds as well as examining the process of electroporation.

2

Relationship between obesity, insulin resistance and cell membrane properties

100%

Ahyayauch H.

European Journal of Clinical and Experimental Medicine

|

2023

|

nr 2

357-364

EN

Introduction and aim. The obesity is one of the greatest public health problems in developing countries and it is a triggering factor for diabetes associated with insulin resistance. The importance of cell membrane lipids as essential regulators of insulin resistance, since changes in the dynamic properties of the cell membrane (e.g., membrane fluidity), could be one of the events by which obesity affects insulin sensitivity. Thus, the insulin resistance may not only be a cause but also a consequence of lipid disorders such as dyslipidemia and/or cell membrane phospholipid composition change. The modification of plasma membrane lipid composition can change membrane biophysical properties and thus influencing protein-lipid interactions, enzymatic activity and regulation of surface receptors. Alterations in the lipid composition modify the fluidity of plasma membranes and the expression of membrane functions, such as receptor binding and enzyme activities. This review summarizes the current knowledge on the effects of the modulation of plasma membrane lipid composition and membrane fluidity in the functionality of membrane proteins involved in insulin activity, including the insulin receptor, glucose transport and Na+/K+ ATPase and, in turn, the key features of the metabolic syndrome. Material and methods. References for that article were found through PubMed and Google Scholar, using terms: “obesity”, “insulin resistance” and “membrane properties”. The research was limited to abstracts and available full-text articles. Analysis of the literature. There is a strong relationship between dietary lipids, membrane lipid profiles and insulin resistance. The changes in the dynamic properties of the cell membrane (e.g., membrane fluidity), could be one of the events by which obesity affects insulin sensitivity. The modification of plasma membrane lipid composition can change membrane biophysical properties and thus influencing protein–lipid interactions, enzymatic activity, and regulation of surface receptors. Modifications of membrane phospholipid composition could have a role in the insulin action by altering membrane fluidity and, as a consequence, the insulin signaling pathway. Conclusion. As conclusion the membrane-lipid therapy approach can be used to treat important pathologies such as obesity and many others diseases such as : cancer, cardiovascular pathologies, neurodegenerative processes, obesity, metabolic disorders, inflammation, and infectious and autoimmune diseases. This pharmacological strategy aims to regulate cell functions by influencing lipid organization and membrane fluidity, inducing a concomitant modulation of membrane protein localization and activity which might serve to reverse the pathological state. Through this review we suggest an in-depth analysis of the membrane lipid therapy field, especially its molecular bases and its relevance to the development of innovative therapeutic approaches.

3

Elimination of selected anions and cations from water by means of the Donnan dialysis

75%

Wiśniewski J. A. , Kabsch-Korbutowicz M.

Environment Protection Engineering

|

2017

|

tom Vol. 43, nr 3

189--205

EN

The usefulness of the Donnan dialysis has been assessed for the elimination of harmful (bromide, bromate and nitrate) or troublesome (calcium and magnesium) ions from water. The rate and efficiency of ion exchange were examined. For anion removal Selemion AM V or Neosepta ACS membranes were used while for cation removal - Neosepta CMX or Selemion CMV ones. The influence of membrane properties and salt concentration in the receiver was investigated.

4

Retention of mycoestrogens in nanofiltration. Impact of feed water chemistry, membrane properties and operating process conditions

51%

Dudziak M.

Environment Protection Engineering

|

2012

|

tom Vol. 38, nr 2

5--17

EN

The membrane process, i.e. nanofiltration, was considered a method for removal of mycoestrogens, compounds recently identified in aqueous environment, from water. The study was focused on the determination of the separation mechanism and on the possibility of removal of mycoestrogens in the applied process. Retention of zearalenone and α-zearalenol was investigated depending on the water matrix composition, the membrane applied, filtration mode and operating conditions of the process. As removed mycoestrogens reveal hydrophobic character, the separation mechanisms is based on the adsorption. Retention of those compounds is also dependent on the membrane type and the filtration mode. The highest effectiveness of mycoestrogens removal was obtained for cellulose membrane (CK), which characterized the highest values of the contact angle and the degree of NaCl removal in comparison with other composite membranes applied. Additionally, the CK membrane showed the highest ability to adsorb investigated micropollutants. However, the variation of retention of mycoestrogens was observed as the membrane surface was modified by inorganic and/or organic substances present in filtrated water. The degree of removal of mycoestrogens during nanofiltration exceeded 81% and considering the effectiveness and the capacity of the process, the cross-flow mode should be applied.