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1

The biomechanical characteristics of spinal dura mater in the context of its basic morphology

Szotek Sylwia, Dawidowicz Joanna, Geniusz Malwina, Kozak Marta, Łukomski Robert, Czogalla Aleksander

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 4

149--159

EN

Purpose: Spinal dura mater plays a crucial role in the biomechanics and protection of the spine. Therefore, the present study investigated the dura mater's mechanical and basic morphological properties to learn more about the biomechanical behaviour of this fibrous membrane. Methods: Tissue strips, oriented in the longitudinal and circumferential directions, were cut from the cervical, thoracic, and lumbar vertebrae parts of the porcine spinal cord. Uniaxial tensile tests were performed using a device with a speed of 4 mm/min until rupture of the sample. Results: It was demonstrated that the dura mater is a heterogeneous, anisotropic material. The longitudinal excised specimens showed the highest values of mechanical properties (ultimate force (FU), the stiffness coefficient (k), ultimate tensile strength (σUTS), and Young’s modulus (E)) compared to those of the circumferentially. Confocal microscopy and sulforhodamine B (SRB) assay enabled us to visualise collagen and elastin elements more efficiently without a need for sample fixation. Conclusions: The spinal dura mater mechanical properties are not uniform along the entire length of the spinal cord, but, in the case of morphological features, no major differences were noticed. The utilisation of SRB occurred to be a non-destructive, fast, and efficient tool for visualising even the smallest elastic fibres on different depths of examined samples. The mechanical and morphological properties of the dura mater provided by this study can be further used in computational modelling to understand injury mechanisms better and help develop injury prevention strategies.

2

Effect of collagen fibres and elastic lamellae content on the mechanical behaviour of abdominal aortic aneurysms

Kobielarz Magdalena

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 3

9--21

EN

Purpose: The main purpose of this study was a detailed analysis of the mechanical and structural characteristics of human abdominal aneurysms in comparison with normal abdominal aortae and determination of the correlations between their mechanical behaviour and the microstructural content. Methods: Various mechanical properties, i.e., mechanical failure properties, elastic moduli, inflection point coordinates, index of anisotropy and incompressibility were determined under uniaxial loading conditions in the circumferential and axial directions. Constitutive parameters were derived from the commonly used constitutive model proposed by Holzapfel et al. [9]. The microstructural arrangement was examined by histological staining supported by scanning electron microscopy analysis. The content of collagen fibres and elastic lamellae was tested in relation to mechanical properties and constitutive parameters. Results: Significant differences were found in the microstructural arrangement and layer composition of the aneurysmal specimens, compared to the normal aorta group. The mechanical properties and constitutive parameters of the aneurysmal specimens were significantly altered, indicating a weakening of the load-bearing properties of the walls of the aneurysms. A comparative analysis discovered significant correlations between structural composition and mechanical parameters, in particular with respect to the number of collagen fibres and failure stress, which can be important for clinical evaluation of abdominal aortic aneurysm (AAA) rupture. Conclusions: Changes in the content of collagen fibres and elastic lamellae correlate with mechanical and constitutive parameters, indicating AAA severity

3

Qualitative Evaluation of the Possible Application of Collagen Fibres: Composite Materials with Mineral Fillers as Insoles for Healthy Footwear

Ławińska K., Serweta W., Modrzewski R.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 5 (131)

81--85

EN

The research presented in this paper focuses on determination of the physical and mechanical properties of composites made on the basis of natural polymer, i.e., crushed collagen fibres which are waste from the leather industry. Mineral supplements such as dolomite, bentonite and kaolin were the filling of the composite produced. Their application was dictated by increasing the application range, and we strove to optimise the composition of the composite in terms of physical and mechanical properties determined in static tensile tests. An analysis of the water absorption capacity was also carried out in order to select optimal compositions which have the best properties. The test results indicate extensive application possibilities of the composites produced, one of which is in footwear insoles, whose quality is an important element determining the hygienic qualities of shoes due to the high density of sweat glands in the plantar part of the foot. This research indicates the possibility of individual development of the composite properties of collagen fibres and mineral supplements in terms of their application, taking into account the medical aspect.

PL

Prezentowane w pracy badania koncentrowały się wokół określenia właściwości fizyko-mechanicznych kompozytów wytwarzanych na bazie naturalnego polimeru jaki stanowią rozdrobnione włókna kolagenowe stanowiące odpad przemysłu skórzanego. Wypełnienie wytwarzanego kompozytu stanowiły dodatki mineralne, takie jak: dolomit, bentonit i kaolin. Ich zastosowanie podyktowane zostało zwiększeniem wachlarza aplikacyjnego oraz dążeniem do optymalizacji składu kompozyty pod kątem właściwości fizyko-mechanicznych określanych w próbach rozciągania statycznego. Przeprowadzono również analizę zdolności chłonięcia wody, w celu wytypowania optymalnych składów, które charakteryzują się najlepszymi właściwościami. Uzyskane wyniki badań wskazują na szerokie możliwości aplikacyjne wytworzonych kompozytów. Jedną z nich stanowią podpodeszwy obuwnicze, których jakość jest istotnym elementem określających walory higieniczne obuwia wobec faktu dużego zagęszczenia gruczołów potowych w podeszwowej części stopy. Przedstawione badania wskazują na możliwość indywidualnego kształtowania cech kompozyty włókien kolagenowych i dodatków mineralnych pod kątem ich aplikacji z uwzględnieniem aspektu medycznego.

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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.

5

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.

6

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.