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1

The intima with early atherosclerotic lesions is load-bearing component of human thoracic aorta

Kobielarz M., Kozuń M., Kuzan A., Maksymowicz K., Witkiewicz W., Pezowicz C.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 1

35--43

EN

The aim of the study was to evaluate the mechanical properties of the adventitia, media, and especially intima of the human thoracic aortic wall in the early stages of atherosclerosis (stage I to III according to the Stary's classification). Histological and immunohistochemical techniques were used to evaluate the severity of atherosclerosis and the correctness of separation of the respective layers. Circumferential specimens of the adventitia, media, and intima (n = 193) were prepared from 27 arteries. The mechanical properties, i.e. the ultimate tensile strength, the maximum strain, and the maximum tangential elastic moduli, were determined in uniaxial tensile test and presented as a median (Me). The tensile strength of the intima (Me = 105 kPa) is comparable to the media (Me = 123 kPa) and lower than for the adventitia (Me = 808.5 kPa). The intima also undergoes the lowest maximum strain (Me = 0.008), and its elastic modulus (Me = 11510 kPa) is significantly higher compared to the media (Me = 5280 kPa). Therefore, presented results indicate that even in the early stages of atherosclerotic development the intima takes part in the process of mechanical loads bearing.

2

The influence of poly(L-lactide) surface modification by CO2 and excimer lasers on mechanical properties

Tomanik M., Kobielarz M., Antończak A., Filipiak J., Pezowicz C.

Engineering of Biomaterials

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2016

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Vol. 19, no. 138 spec. iss.

97

3

Hydrolytic degradation of PLLA and PLGA with surface modified by CO2 laser – preliminary study

Tomanik M., Kobielarz M., Antończak A., Filipiak J., Pezowicz C.

Engineering of Biomaterials

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2016

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Vol. 19, no. 138 spec. iss.

96

4

Influence of selective digestion of elastin and collagen on mechanical properties of human aortas

Kobielarz M., Chwiłkowska A., Turek A., Maksymowicz K., Marciniak M.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 2

55--62

EN

Purpose: There are two families of fibres taking part in the process of mechanical loads transfer, i.e. elastin and collagen fibres. Their number, spatial arrangement and specific properties determine the capacity of a blood vessels to resist mechanical loads resulting from the impact of blood on vessel walls. The purpose of the present paper is to define the load-bearing capacities of elastin and collagen scaffolds equivalent to natural fibre arrangements of human aorta and produced by selective digestion. Methods: Samples of thoracic human aortas were digested by using phosphate buffer of trypsin at pH 8.0 for 22 hours in order to degrade elastin and by autoclaving followed by incubation in 90% formic acid for 22 hours. The efficacy of digestion was assessed immunohistochemically. Mechanical properties of pre-stretched native and digested samples were determined by uniaxial tensile test. Results: Samples subjected to autoclaving have been successfully deprived of both types of collagen and elastin has been intact. Treatment with trypsin caused a removal of elastin and the presence of type I and IV collagen was demonstrated. Digestion of aortic samples either by formic acid or trypsin has resulted significantly decreasing mechanical properties in comparison with native samples. Conclusions: Collagen and elastin scaffold-like stuctures have been effectively produced by selective digestion of thoracic human aorta and their contribution to the load-bearing process was evaluated. Isolated collagen network are more durable and stiffer and less deformable than elastin network, hence are responsible for load-bearing process at higher strain since the range of working of elastin is at lower strain values.

5

Radioisotopic investigation of crosslinking density in bovine pericardium used as a biomaterial

Turek A., Cwalina B., Kobielarz M.

Nukleonika

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2013

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Vol. 58, No. 4

511--517

EN

Stabilized bovine pericardium (BP) belongs to tissues routinely applied in production of heart valves. Commercial products are manufactured from tissues crosslinked by glutaraldehyde (GA). Dye-mediated photooxidation was also proposed as an alternative method, which allows for the elimination of clinical failures of GA-treated tissues. The aim of the study was to investigate the density of BP stabilized by GA and the methylene blue-mediated photooxidation, as compared with a native tissue. Crosslinking density was evaluated based on their ability to accumulate radioactive cobalt ions (60Co2+) and the permeability to these ions. Radioactivity was examined using a γ-spectrophotometer (Packard). The results showed the changes in the crosslinking density between the native tissues and photooxidized or GA-crosslinked tissues. Significant decreases in radioactivity were detected only in the thinnest tissues after photooxidation and in filtrates penetrating the same samples. Photooxidized pericardium of a larger thickness did not reveal any significant changes. Weight-dependence for the permeability was observed in the case of filtrates penetrating the GA-treated tissues. However, 60Co2+-accumulation in these samples remained at the same level. Photooxidation may lead to obtaining biomaterials with advantageous properties, i.e. a decreased calcium-binding capacity. Photooxidation efficiencies were dependent both on compactness and thickness of tissues and on process duration. It should be emphasized that the tissues’ structure after photooxidation was characterized by lower density. This may point to the presence of crosslinks of a smaller compactness in comparison with GA treatment. It has been shown that the factor indeed influencing the result of crosslinking is tissue thickness.

6

Experimental characterization of the mechanical properties of the abdominal aortic aneurysm wall under uniaxial tension

Kobielarz M., Jankowski L. J.

Journal of Theoretical and Applied Mechanics

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2013

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Vol. 51 nr 4

949--958

EN

Although many researchers have made the assumption that the abdominal aortic aneurysym (AAA) wall behaves as an incompressible and isotropic material, the experimental evidence for it is insufficient. Hence, the assumptions about the incompressibility and isotropy of the AAA wall were verified through analysis of stretch ratios of samples excised from the aneurysms walls. The stretch ratios were calculated on the basis of a real-time analysis of geometric dimensions of samples subjected to uniaxial tension. It was proved that the walls of abdominal aortic aneurysms can be modelled as an incompressible and isotropic material. Using histological techniques, the assumption concerning the negligence of shear stress in the analysis of AAA wall stresses was indirectly validated. The results were incorporated into a hyperelastic constitutive equation.

7

Spectroscopic techniques in the study of human tissues and their components. Part I, IR spectroscopy

Olsztyńska-Janus S., Szymborska-Małek K., Gąsior-Głogowska M., Walski T., Komorowska M., Witkiewicz W., Pezowicz C., Kobielarz M.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 3

101-115

EN

Among the currently used methods of monitoring human tissues and their components many types of research are distinguished. These include spectroscopic techniques. The advantage of these techniques is the small amount of sample required, the rapid process of recording the spectra, and most importantly in the case of biological samples - preparation of tissues is not required. In this work, vibrational spectroscopy: ATR-FTIR and Raman spectroscopy will be used. Studies are carried out on tissues: tendons, blood vessels, skin, red blood cells and biological components: amino acids, proteins, DNA, plasma, and deposits.

8

Spectroscopic techniques in the study of human tissues and their components. Part II, Raman spectroscopy

Olsztyńska-Janus S., Gąsior-Głogowska M., Szymborska-Małek K., Komorowska M., Witkiewicz W., Pezowicz C., Szotek S., Kobielarz M.

Acta of Bioengineering and Biomechanics

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2012

|

Vol. 14, no. 4

121-133

EN

Among the currently used methods of monitoring human tissues and their components many types of research are distinguished. These include spectroscopic techniques. The advantage of these techniques is the small amount of sample required the rapid process of recording the spectra, and most importantly in the case of biological samples - preparation of tissues is not required. In this work vibrational spectroscopy: ATR-FTIR and Raman spectroscopy will be used. Studies are carried out on tissues: tendons, blood vessels, skin, red blood cells and biological components: amino acids, proteins, DNA, plasma, and deposits.

9

Elastin and collagen fibres alterations for abdominal aortic aneurysms population with constant maximum diameter size

Kobielarz M., Maksymowicz K., Będziński R.

Engineering of Biomaterials

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2011

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Vol. 14, no. 102

2--6

EN

Development of abdominal aortic aneurysm (AAA) is a dynamic process proceeding as a result of the multi-factor pathological remodelling of elastin and collagen fibres, results an aneurysm expansion. In clinical practice, development of AAA is identified with aneurysm growth. Hence, the aim of this paper is to propose a taxonomy of load-bearing structural components alterations for AAA with relatively constant maximum diameter (average diameter 6.9±0.8 cm). Structural investigations of normal (n=47) and aneurismal (n=46) vessels were carried out on the basis of histological and ultrastructural examinations. The histological preparations were subjected to histometric evaluation; the number of collagen and elastin fibres and additionally the thickness of the particular vascular wall layers. A qualitative analysis of the abdominal aortic wall, mainly estimation of fibres arrangement, based on histological and ultrastructural (SEM) examinations were additionally performed. Using a cluster analysis, three stages of load-bearing fibres alterations for AAA population were distinguished. The clusters were systematized according to NAA results. For AAA population with relatively constant maximum diameter in the first stage of load-bearing fibres remodeling was observed a substantial loss of elastin fibres. The second stage is characterized by an increase in the number of collagen fibres. In the final stage the number of collagen is dramatically reduced. Presented results provide evidence to risk of AAA rupture is not connected with AAA size but a remodelling of extra-cellular matrix proteins. The remodelling is accompanied by changes in the AAA wall thickness, which should be taken into consideration when evaluating the degree of advancement of this disease.

10

Mechanobiology of soft tissues: FT-Raman spectroscopic studies

Gąsior-Głogowska M., Komorowska M., Hanuza J., Mączka M., Będziński R., Kobielarz M.

Challenges of Modern Technology

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2011

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Vol. 2, no. 3

8--11

EN

FT-Raman spectroscopy was used to investigate microstructural changes in the secondary protein structure of soft tissues subjected to increasing levels of macroscopic strain. Main protein bands at 938 cm-1 assigned as v(Cα–C), 1668 cm-1 — amide I and 1268 cm-1 — amide III are sensitive to applied strain and undergo wavenumber shifting. Other main vibrational modes at 1004 cm-1 assigned to the phenyl ring breathing mode and 2940 cm-1 (n(CH3,CH2)) remain unaltered. Spectroscopic results were compared with the mechanical relations obtained from the standard protocol of uniaxial tensile tests carried out in a testing machine. A clear correlation between Raman band shifting and the level of mechanical stress was established. Initially the load is transferred through elastin and then gradually also by collagen. It was proved that transferring loads by soft tissues involves changes in structural protein conformation. This process was described in detail for a tendon. It was also confirmed that mechanical properties of soft tissues depend on collagen and elastin fiers orientation.

11

Determination of the mechanical properties of the skin of pig foetuses with respect to its structure

Żak M., Kuropka P., Kobielarz M., Dudek A., Kaleta-Kuratewicz K., Szotek S.

Acta of Bioengineering and Biomechanics

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2011

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Vol. 13, no. 2

37-43

EN

Skin is an important barrier protecting the organism against external environmental factors. Determination of its mechanical characteristics as regards its structure has significant scientific and application value. In this work, uniaxial tensile tests were conducted to determine the basic mechanical parameters of skin with respect to its structure. The subject of the study were skin samples taken from domestic pig foetuses. They were excised from different parts of body, in the direction parallel to the long axis of the body. Regardless of the sampling site, the tests revealed no significant differences in the values of the maximum tensile strength (2.08 +- 0.25 MPa) and the conventional Young's modulus (5.87 +- 1.52 MPa). The mechanical and structural tests confirmed that regardless of the sampling region the skin of domestic pig foetuses may constitute a human skin substitute model.

12

Wpływ fotooksydacji w obecności błękitu metylenowego na właściwości mechaniczne osierdzia świni

Turek A., Kobielarz M., Cwalina B., Będziński R.

Engineering of Biomaterials

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2010

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Vol. 13, no. 96-98

99--103

PL

Eliminacja najczęstszych wad stabilizacji tkanek zwierzęcych bogatych w kolagen jest przyczyną poszukiwań nowych metod ich przetwarzania. Celem przedstawionych badań było określenie właściwości mechanicznych osierdzia włóknistego świni domowej po fotostabilizacji przez 8 h i 24 h w obecności światła białego (50 W) i 0,05% roztworu błękitu metylenowego. Badania przeprowadzono z wykorzystaniem testu jednoosiowego rozciągania tkanek ze stałą prędkością 0,3 mm/s, w warunkach pełnego ich uwodnienia w 0,9% roztworze chlorku sodu. Przeprowadzone badania ujawniły istotne zmniejszenie siły zrywającej w przypadku tkanek poddanych fotooksydacji, przy zachowaniu ich sztywności i wartości wydłużenia. W prezentowanych badaniach wykazano, iż fotostabilizacja wpływa na właściwości mechaniczne osierdzia.

EN

The elimination of the most frequent drawbacks resulting from stabilization of animal collagen-rich tissues is the reason for seeking novel methods of their processing. The aim of this work was the determination of mechanical properties of fibrous porcine pericardium after 8 h and 24 h photostabilization in the presence of visible light (50 W) and 0.05% solution of methylene blue. Uniaxial tensile test of tissue specimens was performed with constant rate at 0.3 mm/s, in the condition of full-hydration in 0.9% sodium chloride solution. The studies showed significant decrease of failure force in the case of photooxidized tissues, with preservation of the stiffness and values of maximum extension. The studies have shown that photostabilization influences the mechanical properties of pericardium.

13

Ocena histologiczna i ultrastrukturalna ścian tętniaków aorty brzusznej

Kobielarz M., Maksymowicz K., Kaleta K., Kuropka P., Marycz K., Będziński R.

Engineering of Biomaterials

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2010

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Vol. 13, no. 99-101

83--87

PL

Rozwój tętniaków, w tym aorty brzusznej (AAA) jest dynamicznym procesem, który zachodzi w wyniku wieloczynnikowego, patologicznego remodelingu tkanki łącznej ściany aorty. Badania strukturalne ścian naczyń tętniczych (zdrowych i z tętniakiem) przeprowadzono w oparciu o analizę histologiczną i ultrastrukturalną. Analiza porównawcza wyników wykazała, że w przypadku preparatów ścian tętniaków aorty brzusznej odnotowano cały szereg zmian, które są charakterystyczne dla rozważanego schorzenia, w tym: wzmożony proces neowaskularyzacji oraz obecność nacieku zapalnego. Ponadto, odnotowano zatarcie granic między warstwami oraz redukcję ich grubości, co szczególnie zaznaczyło się w przypadku błony wewnętrznej. Zaobserwowano istotny ubytek włókien elastynowych oraz zmienny co do intensywności w poszczególnych przypadkach ubytek włókien kolagenowych. Wykazano także, że zmiany w liczbie włókien tkanki łącznej odgrywają kluczową rolę w procesie rozwoju AAA.

EN

The development of abdominal aortic aneurysm (AAA) is a dynamic process proceeding as a result of the multi-factor pathological remodelling of the connective tissue. Structural investigations of normal and aneurismal vessels were carried out on the basis of histological and ultrastructural examinations. A comparative analysis of the experimental results revealed a whole series of changes characteristic of the AAA walls (intensified neovascularisation and inflammatory infiltrations). In addition, the boundaries between the layers were found to be blurred and the thickness of the layers was reduced. A substantial loss of elastin fibres and a case-specific loss of collagen fibres were observed. The number of connective tissue fibres play a key role in the AAA development.

14

Ocena możliwości automatyzacji układu do rozciągania próbek na użytek spektroskopii Ramana

Wilk J., Klonecki-Olech K., Kobielarz M.

Aktualne Problemy Biomechaniki

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2010

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z. 4

275--278

PL

Badania ścian naczyń krwionośnych metodą spektroskopii Ramana, pozwalają na badanie zależności między obciążeniem jakiemu poddawana jest tkanka, a jej strukturą. W celu zwiększenia efektywności pomiarów podjęta została próba zautomatyzowania układu służącego do rozciągania próbek poddawanych badaniu.

EN

Study of vessels walls by means of Raman Spectroscopy allows to analyze the relation between load placed upon the tissue and it’s structure. To maximize the effectiveness of measurement, the goal of automation of the tensile tool used in the procedure was undertaken.

15

Structural alteration of collagen fibres - spectroscopic and mechanical studies

Gąsior-Głogowska M., Komorowska M., Hanuza J., Ptak M., Kobielarz M.

Acta of Bioengineering and Biomechanics

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2010

|

Vol. 12, no. 4

55-62

EN

Fourier Transform Near Infrared Raman Spectroscopy has been used to monitor the molecular changes of collagen in a tendon subjected to strain. In the Raman spectrum of the unstrained tendon, some protein bands, mainly assigned to collagen, can be observed: amide I (1666 cm–1) and III (1266 and 1248 cm–1) vibrational modes and skeletal (C–C) stretching vibrations (816 and 940 cm–1). The position of these bands is changing with the increasing strain values. It is concluded that elastin and non-helical domains of collagen are initially involved in the load transfer and triple helices of collagen are gradually joining this process.

16

Skanowanie 3D jako metoda obrazowania złożonych i rozległych relacji przestrzennych dla potrzeb medycyny sądowej i kryminalistyki - ocena przydatności

Maksymowicz K., Kobielarz M., Jurek T.

Wiadomości Konserwatorskie

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2009

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Nr 26

689-695

PL

Oparta na skanerze laserowym 3D metoda dokumentacji otworzyła nowe horyzonty dla medycyny sądowej i kryminalistyki, głównie ze względu na jej zdolność faktycznie 'zamrożenia' jakiegokolwiek miejsca przestępstwa. Niektóre cechy, takie jak wysoka rozdzielczość zapisywania danych tworzących obraz, zachowując badany przedmiot w stanie nietkniętym, szybkość gromadzenia danych, możliwość bieżącego zapisu danych w postaci pliku i przesyłania ich na dowolną odległość, niski koszt pojedynczych oględzin, prostota konserwacji skanera, jego mobilność, niezależność od zewnętrznych źródeł energii, możliwości kooperacji z każdym rodzajem narzędzia badawczego operującego w technice cyfrowej, stawiają skaner 3D w roli przydatnego i wszechstronnego narzędzia w codziennej praktyce medycyny sądowej i kryminalistyki.

EN

Based on 3D laser scanner method of documentation has opened new prospects for forensic medicine and crime detection, mainly in respect to its ability to virtually efreezei any crime scene. Some features like high resolution of the imaging data recording, preserving the examined object in intact state, speed of data collection, possibility of instant data filing and transmission at any distance, low cost of singular examination, simplicity of scanner maintenance, its mobility, independence from an external source of energy, possibility of cooperation with every kind of research tool working in digital technique, put the 3D scanner as a useful and versatile tool in everyday forensic medicine and crime detection practice.

17

Właściwości skóry ludzkiej uzyskane w testach mechanicznych i techniką spektroskopii Ramana

Szotek S., Będziński R., Kobielarz M., Gąsior-Głogowska M., Komorowska M., Maksymowicz K., Hanuza J., Hermanowicz K.

Engineering of Biomaterials

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2009

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Vol. 12, no. 89-91

207--209

PL

Celem przeprowadzonych badań było porównanie charakterystyk otrzymanych: w testach wytrzymałościowych i z pomiarów spektroskopowych. W pracy wyznaczono podstawowe parametry mechaniczne skóry, które są zdeterminowane ułożeniem włókien kolagenowych. Następnie zarejestrowano widma ramanowskie badanej tkanki, zidentyfikowano pasma charakterystyczne dla białka kolagenowego. Na podstawie analizy uzyskanych wyników, dla kolejnych etapów rozciągnięcia skóry, zaobserwowano między innymi różnice w położeniu maksimum pasma amidu I (1658cm-1) w zależności od kierunku rozciągania próbki. Porównanie, w obu metodach charakterystycznych zakresów, zachodzących zmian wykazało możliwość stosowania Spektroskopii Ramana w celu wyznaczenia kierunku ułożenia włókien kolagenowych w trakcie rozciągania co jest istotne z punktu widzenia przeszczepów skóry.

EN

The aim of the investigations was to compare the characteristics obtained from strength tests and spectroscopic measurements. The basic skin parameters dependent on the arrangement of collagen fibres were determined. Then Raman spectra of the investigated tissue were recorded and bands characteristic of collagen protein were identified. An analysis of the results for the successive stages of skin stretching showed, among other things, differences in the location of the amid I band maximum (1658cm-1) depending on the direction of specimen stretching. A comparison of the characteristic ranges of change determined by the two methods showed that Raman spectroscopy can be used to ascertain the orientation of collagen fibres in the course of stretching, which information is essential for skin transplantation.

18

Analiza porównawcza składu pierwiastkowego ścian aorty brzusznej i tętniaka aorty brzusznej

Kobielarz M., Marycz K., Szotek S., Będziński R.

Engineering of Biomaterials

|

2009

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Vol. 12, no. 89-91

185--187

PL

Głównym celem pracy było określenie procentowego składu pierwiastkowego ścian zdrowej aorty brzusznej (NAA) i tętniaka aorty brzusznej (AAA) na podstawie mikroanalizy rentgenowskiej (Rtg) dla dużej populacji materiału badawczego, ażeby sprawdzić użyteczność metody do różnicowania (na poziomie molekularnym) materiału biologicznego pod kątem zmian chorobowych. Dla żadnego z analizowanych pierwiastków nie odnotowano, na poziomie istotności p=0,05, istotnych statystycznie zmian w procentowym rozkładzie pierwiastków między preparatami ścian zdrowych aort brzusznych oraz tętniaków. Na podstawie uzyskanych wyników wykazano, biorąc pod uwagę wielkość grup badawczych, że zastosowana metoda nie umożliwia różnicowania materiału biologicznego na założonym poziomie istotności.

EN

The main aim of paper was evaluation of chemical elements composition of normal abdominal aortic walls (NAA) and abdominal aortic aneurysms walls (AAA) based on X-ray microanalysis for a numerous and diversified population in order to differentiate (on molecular level) biological materials according pathological changes. For neither of analyzed elements were noticed statistically significant on the confidence level p=0,05 differences between NAA walls and AAA walls. On the basis of the obtained results it can be concluded that used methods isn’t sufficient to differentiation of biological materials according pathological changes.

19

Effect of diet on mechanical properties of horse's hair

Kania M., Mikołajewska D., Marycz K., Kobielarz M.

Acta of Bioengineering and Biomechanics

|

2009

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Vol. 11, nr 3

53-57

EN

The aim of this research was to assess the effect of diet supplementation with zinc and copper, in different chemical forms (organic and inorganic), on the mechanical properties of the hair of healthy English thoroughbred horses. Hairs were taken from 18 horses which had been fed with oats and hay for a period of 110 days. Twelve of the horses had been additionally given a daily dose of 700 g of highquality 44-ingredients Fohlengold St-Hippolyt muesli made by Muhle Ebert Dilheim. Six of them had received the muesli-containing organic zinc and copper (OS), while the other six horses had received the muesli-containing inorganic zinc and copper (IS). The mechanical properties of the hairs before and after the supplementation period were tested in a Synergie 100 (MTS) testing machine. Each of the hairs was loaded at a constant rate of 20 mm/min until rupture. Young modulus (E), breaking stress (Ru) and yield point (Rs) of the particular hairs were determined. No significant changes in the mechanical parameters were observed in the reference group in which the horses were fed with only oats and hay for the whole experimental period of 110 days. The supplementation of the diet with inorganic zinc and copper resulted in an increase in the elasticity and diameter of the hairs and in a simultaneous reduction in their strength. Whereas organic zinc and copper caused an increase in the elasticity and strength of the hairs and a simultaneous reduction in their diameter. It has been shown that the organic form of the supplemented trace zinc and copper (mainly copper) elements has a beneficial effect on the mechanical properties of the hairs since it results in an increase in both their elasticity and strength.

20

Właściwości mechaniczne i strukturalne tętniaków aorty brzusznej

Kobielarz M., Szotek S., Kuropka P., Kaleta K.

Engineering of Biomaterials

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2008

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Vol. 11, no. 81-84

98--100

PL

W celu oszacowania prawdopodobieństwa przerwania ciągłości ściany tętniaka aorty brzusznej (AAA) konieczne jest zbadanie warunków obciążeniowych odpowiedzialnych za to zdarzenie, a także identyfikacja zmian zachodzących w strukturze ściany tego naczynia w procesie rozwoju schorzenia. Stąd, głównym celem prezentowanej pracy jest określenie mechanicznych oraz strukturalnych właściwości ścian tętniaków aorty brzusznej oraz preparatów zdrowych aort. W tym celu zastosowano test jednoosiowego rozciągania próbek wyciętych z pobranych preparatów w dwóch prostopadłych do siebie kierunkach: wzdłużnym oraz obwodowym, a także przeprowadzono histologiczne badania mikrostruktury ściany naczyń. Na podstawie przeprowadzonego testu wytrzymałościowego wykreślono krzywą naprężenie-odkształcenie dla każdego przebadanego przypadku i wyznaczono charakterystyczne wielkości opisujące wytrzymałość oraz sztywność przebadanych próbek. Uzyskane wyniki wskazują na istotny wzrost sztywności w przypadku preparatów ścian tętniaków, co szczególnie zaznaczyło się w kierunku obwodowym.

EN

To estimate when an abdominal aortic aneurysm (AAA) may rupture, it is necessary to understand the forces responsible for this event and structural alterations lead to changes in the mechanical properties of the tissue. Hence, the main goal of presented study is determination and assessment of mechanical and structural properties of the walls of normal abdominal aortas and abdominal aortic aneurysms. With this end in view uniaxial tensile tests of the specimens cut out from the walls of abdominal aortic aneurysms and normal abdominal aortas in two directions - longitudinal and circumferential - have been carried out and histological study has been performed. On the basis of these tests the stress-strain relationships have been determined for each investigated specimen and the maximum tangential modulus as well as the ultimate tensile strength has been assigned. The results indicate the increase of tissue stiffness in the case of abdominal aortic aneurysms, especially in the circumferential direction.