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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.

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Rola składników aktywnych w procesie starzenia się skóry

Łubkowska B., Grobelna B., Maćkiewicz Z.

Wiadomości Chemiczne

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2010

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[Z] 64, 11-12

1053-1071

EN

Skin is the coating of all human and animal organisms. It is a kind of space where different processes take place. Skin is the largest and the heaviest organ in the body. Also, it is a barrier, that stops water and the part of body, which should be particularly protected [1]. The skin is composed of three main layers: epidermis (Fig. 1), dermis (Fig. 3) and subcutaneous tissue (Fig. 5). Each of these layers has completely different role and is characterized by various properties. Epidermis is the outermost layer of skin. It consists of a living and a dead zone. The living area forms new cells which are the subject to further changes, while in the zone of dead cells they are highly flattened and devoid of nuclei [2]. In the epidermis, exactly in the reproductive output layer there are melanocytes, which are cells responsible for production of the pigment - melanin (Fig. 2). Melanin is responsible for color of hair, eyes and skin. It is formed from tyrosine as a result of numerous biochemical reactions [3]. Biological activity of melanin is determined by the presence of appropriate peptide. The sequences of its active components are: Ser-Tyr, Ser-Met-Glu-His-Phe-Arg, and Trp-Gly-Lys-Pro-Val. It is possible to protect the skin also against the solar radiation. The hormone MSH absorbs and reflects UV radiation. Under the influence of UV radiation the amount of melanin increases, causing temporary changes in skin color [3]. Under the epidermis there is a proper skin, which is composed of elastic fibers, collagen fibers, and the basic substance, which fuses the fiber elements. The elastic fibers are scattered among collagen fibers. Proper skin is the place where a valuable protein - very important in cosmetics - occurs - the native collagen. It is the main protein of connective tissue. Collagen has a very high tensile strength and is a major component of tendons. It is responsible for skin elasticity. Loss of collagen from the skin causes wrinkles [4]. A distinctive layer of skin is the subcutaneous tissue. It combines dermis with muscles. It is composed of fat cells separated by connective tissue. The size and the shape of fat cells vary depending on gender, diet and also age [5]. Skin, like other authorities is aging. These process may be accelerated or delayed under the influence of various endogenous and exogenous elements (Tab. 1). Also genetic predisposition are of significant importance. It seems that, as soon as we age, we inherit from our ancestors. To delay the aging process, it is necessary to properly take care of and protect the skin. There are many ways to delay aging of the skin. The most successful, for example cosmetics with active ingredients such as peptides, will be presented here.

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Charakterystyka usieciowanych biomateriałów na bazie kolagenu i elastyny

Skopińska-Wiśniewska J., Sionkowska A., Gawron M., Kozłowska J., Płanecka A.

Engineering of Biomaterials

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2010

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Vol. 13, no. 99-101

97--99

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Efekty sieciowania osierdzia świni badane za pomocą spektroskopii EPR - metody znakowania spinowego

Cwalina B., Dul L.

Inżynieria Biomateriałów

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2002

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R. 5, nr 23-25

61-64

PL

Celem pracy była ocena udziału eta-aminowych grup lizyny w elastynie, jak również eta-aminowych grup lizyny i hydroksylizyny w kolagenie w modyfikacji tkanki osierdziowej za pomocą glutaraldehydu (GA). Materiałami badanymi były: nierozpuszczalny kolagen typu I, elastyna i osierdzie włókniste świni, zarówno natywne i usieciowane glutaraldehydem. Do badania efektu sieciowania wykorzystano spektroskopię elektronowego rezonansu paramagnetycznego (EPR) - metodę znakowania spinowego (znacznik spinowy: izotiocyjaniano-Tempo; ITCTO). Można stwierdzić, że w procesie sieciowania tkanki kolagenowej przez GA uczestniczą grupy eta-aminowe zarówno lizyny i hydroksylizyny. W czystym kolagenie GA reaguje zarówno z grupami eta-aminowymi hydroksylizyny.

EN

The aim of his work was to elucidate contribution of the etha-amino groups of lysine in elastin as well as of the etha-amino groups of lysine and hydroxylysine in collagen to the pericardial tissue modification by means of glutaraldehyde (GA). The investigated materials were: insoluble collagen type I, elastin and porcine fibrous pericardium, both native and crosslinked with glutaraldehyde. The electron paramagnetic resonance (EPR) spectroscopy - method of spin labeling (spin label: isothiocyanato-Tempo; ITCTO) - has been used for study of the crosslinking-effects. It may be stated that in process of collagenous tissue crosslinking by GA participate etha-amino groups of both lysine and hydroxylysine. In pure collagen, GA reacts mainly with etha-amino groups of hydroxylysine.