Animal Soft Tissue Research Articles

Mechanical properties of animal ligaments: a review and comparative study for the identification of the most suitable human ligament surrogates.

The interest in the properties of animal soft tissues is often related to the desire to find an animal model to replace human counterparts due to the unsteady availability of human tissues for experimental purposes. Once the most appropriate animal model is identified, it is possible to carry out ex-vivo and in-vivo studies for the repair of ligamentous tissues and performance testing of replacement and support healing devices. This work aims to present a systematic review of the mechanical properties of ligaments reported in the scientific literature by considering different anatomical regions in humans and several animal species. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. Moreover, considering the lack of a standard protocol for preconditioning of tissues, this aspect is also addressed. Ninety-six studies were selected for the systematic review and analysed. The mechanical properties of different animal species are reported and summarised in tables. Only results from studies reporting the strain rate parameter were considered for comparison with human ligaments, as they were deemed more reliable. Elastic modulus, ultimate tensile stress, and ultimate strain properties are graphically reported identifying the range of values for each animal species and to facilitate comparison between values reported in the scientific literature in animal and human ligaments. Useful similarities between the mechanical properties of swine, cow, and rat and human ligaments have been found.

Difficulties and artefacts in cryo-fixation of ovarian tissues for X-ray fluorescence analyses

Even though measurements in cryogenic conditions are the preferred choice for single-cell and plant analyses, cryo-fixation of human or animal soft tissues for X-ray fluorescence analysis still remains challenging.

Multiple mechanisms behind plant bending.

To survive, plants constantly adapt their body shape to their environment. This often involves remarkably rapid bending of their organs such as stems, leaves and roots. Since plant cells are enclosed by stiff cell walls, they use various strategies for bending their organs, which differ from bending mechanisms of soft animal tissues and involve larger physical forces. Here we attempt to summarize and link different viewpoints on bending mechanisms: genes and signalling, mathematical modelling and biomechanics. We argue that quantifying cell growth and physical forces could open a new level in our understanding of bending and resolve some of its paradoxes.

Probing Local Force Propagation in Tensed Fibrous Gels.

Fibrous hydrogels are a key component of soft animal tissues. They support cellular functions and facilitate efficient mechanical communication between cells. Due to their nonlinear mechanical properties, fibrous materials display non-trivial force propagation at the microscale, that is enhanced compared to that of linear-elastic materials. In the body, tissues are constantly subjected to external loads that tense or compress them, modifying their micro-mechanical properties into an anisotropic state. However, it is unknown how force propagation is modified by this isotropic-to-anisotropic transition. Here, force propagation in tensed fibrin hydrogels is directly measured. Local perturbations are induced by oscillating microspheres using optical tweezers. 1-point and 2-point microrheology are combined to simultaneously measure the shear modulus and force propagation. A mathematical framework to quantify anisotropic force propagation trends is suggested. Results show that force propagation becomes anisotropic in tensed gels, with, surprisingly, stronger response to perturbations perpendicular to the axis of tension. Importantly, external tension can also increase the range of force transmission. Possible implications and future directions for research are discussed. These results suggest a mechanism for favored directions of mechanical communication between cells in a tissue under external loads.

Modeling via peridynamics for large deformation and progressive fracture of hyperelastic materials

Hyperelastic materials are frequently observed in the natural world and engineering applications such as rubbers and animal soft tissues. Modeling large deformation and progressive fracture of these materials is challenging for grid-based methods due to the severe mesh distortions at crack tips. To address this problem, we proposed a novel meshfree framework using bond-based peridynamics (PD) based on finite deformation theory. The proposed modeling framework has the following novelties: (1) An original bond strain, derived from the spectrum representation of hyperelastic models is used to describe the nonlinear bond force-stretch relationship, which gives more concise and robust solutions to large deformation problems; (2) A numerical damping parameter inspired by the mass–dashpot–spring system is developed to endow the proposed framework with numerical advantages in terms of enhancing the stability of explicit time integration in modeling quasi-static problems; (3) It outperforms grid-based methods in capturing notable features like non-smooth crack surfaces, secondary damages, and materials fragmentations. The capability of our framework was successfully validated via several examples, including large deformation, crack initiation and propagation tests of specimens with various notches and eccentric holes. Besides, the numerical performance of our model to capture the crack deflection in laminate rubber specimens was also tested, with results showing good consistency with experimental observations. This framework is compatible with diverse hyperelastic models and sheds new light on modeling of elastomer-hydrogel composites and soft tissues.

Анализ особенностей захоронения остатков животных мамонтовой фауны и ископаемой мамонтовой кости

The article presents the results of analyzing characteristics of burying mammoth fauna animal remains. The finds coordinates were linked to the engineering-geological map of the Republic of Sakha (Yakutia) (1:1 500 000). Extensive literary data describing the burials taphonomy are taken into account. It has been found that most of the finds were buried in deposits of small fractions (loess-like loams, sandy loams, sands) characteristic for the edoma (ice complex) providing the unique preservation for bone and soft tissues of animals.

Can Heart Valve Decellularization Be Standardized? A Review of the Parameters Used for the Quality Control of Decellularization Processes.

When a tissue or an organ is considered, the attention inevitably falls on the complex and delicate mechanisms regulating the correct interaction of billions of cells that populate it. However, the most critical component for the functionality of specific tissue or organ is not the cell, but the cell-secreted three-dimensional structure known as the extracellular matrix (ECM). Without the presence of an adequate ECM, there would be no optimal support and stimuli for the cellular component to replicate, communicate and interact properly, thus compromising cell dynamics and behaviour and contributing to the loss of tissue-specific cellular phenotype and functions. The limitations of the current bioprosthetic implantable medical devices have led researchers to explore tissue engineering constructs, predominantly using animal tissues as a potentially unlimited source of materials. The high homology of the protein sequences that compose the mammalian ECM, can be exploited to convert a soft animal tissue into a human autologous functional and long-lasting prosthesis ensuring the viability of the cells and maintaining the proper biomechanical function. Decellularization has been shown to be a highly promising technique to generate tissue-specific ECM-derived products for multiple applications, although it might comprise very complex processes that involve the simultaneous use of chemical, biochemical, physical and enzymatic protocols. Several different approaches have been reported in the literature for the treatment of bone, cartilage, adipose, dermal, neural and cardiovascular tissues, as well as skeletal muscle, tendons and gastrointestinal tract matrices. However, most of these reports refer to experimental data. This paper reviews the most common and latest decellularization approaches that have been adopted in cardiovascular tissue engineering. The efficacy of cells removal was specifically reviewed and discussed, together with the parameters that could be used as quality control markers for the evaluation of the effectiveness of decellularization and tissue biocompatibility. The purpose was to provide a panel of parameters that can be shared and taken into consideration by the scientific community to achieve more efficient, comparable, and reliable experimental research results and a faster technology transfer to the market.

Вивчення ступеня інтеграції м’яких тканин в елементи з вуглець-вуглецевого композитного матеріалу в зоні переходу внутрішнього та зовнішнього середовища при імплантації ендо-екзопротезів

Щороку в Україні виконується близько 600 ампутацій на рівні стегна, що вимагає подальшої реабілітації у вигляді протезування втраченої кінцівки. Стандартним методом кріплення протеза до кукси стегна є фіксація гільзи протеза навколо кукси. Гільза забезпечує передачу навантаження, стабільність і ефективний контроль над протезом. Однак цей метод фіксації часто згадується як незадовільний через низку ускладнень, таких як виразки і подразнення шкіри, пітливість у гільзі, неможливість ходити по пересіченій місцевості, неналежний контроль над протезом, зниження діапазону рухів стегна і болі в ділянці кукси. Альтернативним рішенням є перкутанне кріплення протеза ноги до стегнової кістки за допомогою остеоінтегрованих імплантатів. Використовувалися інтрамедулярні стрижні з титановим покриттям, поєднані із зовнішнім блоком за допомогою замка, накритого силіконовою прокладкою, що виконує функцію розмежування внутрішнього середовища від зовнішнього, що часто призводило до інфекційно-запальних ускладнень. Пошук матеріалів для вирішення цих проблем зупинився на вуглецевих матеріалах, у тому числі вуглець-вуглецевих композитних матеріалах (ВВКМ), які є відносно новими конструкційними матеріалами в практиці ортопедії. Їх успішно використовують при остеосинтезі та ендопротезуванні кісток завдяки комплексу необхідних фізико-механічних і хімічних властивостей. Метою даної роботи було встановити ступінь інтеграції м’яких тканин і, зокрема шкірного покриву, в ВВКМ. Експериментальним шляхом, із використанням лабораторних тварин, проведено гістоморфологічний аналіз змін тканин в ділянці контакту з імплантатами. Доведено біоінертність матеріалу, а також обґрунтовано перспективність застосування імплантатів із ВВКМ як покриття елементів конструкцій ендо-екзопротезів для застосування в реконструктивній травматології та ортопедії.

A STUDY OF WARMING DEVICES AND PERIOPERATIVE FACTORS POTENTIALLY CONTRIBUTING TO SURGICAL FIELD CONTAMINATION IN SMALL ANIMAL PATIENTS

Bacterial contamination on surgical drapes may increase the risk of surgical site infection (SSI). This preliminary investigation analyzed the relationship between forced-air warming devices and bacterial contamination on surgical drapes in small animal soft tissue surgery settings. The subjects of this study were canine and feline patients enrolled in clean surgical procedures at the National Taiwan University Veterinary Hospital. Bacterial colonies on surgical drapes were sampled on agar plates immediately prior to and 1[Formula: see text]h after skin incision. Cases with bacteria growth on the post-incision sampled agar were considered with surgical field contamination (SFC). Intraoperative warming methods (forced-air warming systems or circulating water blankets) and other factors that potentially contribute to SFC (drape material, patient features, surgical procedure types, surgeons, and number of operating room personnel) were recorded. The study comprised 57 operations, 28 cases belonged to the circulating water blanket group and 29 belonged to the forced-air warming system group. No differences in contamination rate were detected among intraoperative warming methods, drape materials, patient characteristics, surgical procedure types, or number of operating room personnel. However, a significant difference in contamination rate was detected among surgeons.

Applications of Hyaluronic Acid in Ophthalmology and Contact Lenses.

Hyaluronic acid (HA) is a glycosaminoglycan that was first isolated and identified from the vitreous body of a bull’s eye. HA is ubiquitous in the soft connective tissues of animals and therefore has high tissue compatibility for use in medication. Because of HA’s biological safety and water retention properties, it has many ophthalmology-related applications, such as in intravitreal injection, dry eye treatment, and contact lenses. Due to its broad range of applications, the identification and quantification of HA is a critical topic. This review article discusses current methods for analyzing HA. Contact lenses have become a widely used medical device, with HA commonly used as an additive to their production material, surface coating, and multipurpose solution. HA molecules on contact lenses retain moisture and increase the wearer’s comfort. HA absorbed by contact lenses can also gradually release to the anterior segment of the eyes to treat dry eye. This review discusses applications of HA in ophthalmology.

Morphological features of the simulated gunshot wounds of rabbits’ soft tissues at different temperatures of injuring object

The article presents the results of experimental modeling of super­ficial fragment gunshot wounds of soft tissues, obtained in low-energy gunshot wounds. The pathomorphosis of gunshot wounds was studied, and the features and timing of their healing were compared depending on the temperature of the damaging fragments. The aim of the work was to study the effect of the temperature of the injuring shrapnel on the healing processes of the soft tissues of experimental animals with superficial low-energy fragment gunshot wounds. Using the random number method, laboratory animals (rabbits) were divided into 3 experimental groups (15 animals each). In each group, wounding was with fragments with different temperatures − 18°С, 50°С and 100°С. The control group consisted of 10 intact animals. On day 14th, 30th and 60th, 5 animals from each group were withdrawn from the experiment. Microscopic examination of soft tissues was performed using a PRIMO STAR light microscope (Carl Zeiss, Germany) at magnification by 56 and 400 times. When assessing the state of tissues in the area of wound damage, it was established that as the temperature of the injuring fragment increases, a slower filling of the defect formed by the necrotic detritus in the process of utilization of necrotic detritus is observed. The high temperature of the injuring fragment along with the mechanical rupture of tissues causes thermal coagulation necrosis. Dense coagulated necrotic masses covering the wound canal from the inside, not only increase the volume of necrotic masses, but also complicate the process of wound healing. At a temperature of wounding fragments 100°C, the formation of a necrotic crust on the surface of the wound occurred on average 3±1.2 days later than at temperatures of 18°C and 50°C, the least pronounced healing took place at the bottom of the wound and in the muscle tissue. Microscopically necrotic, not dystrophic changes were observed in myocytes. Thus, a comparative analysis of the pathomorphosis of soft tissues in a wound when injured from an air rifle MP-532 with different temperature of the fragments showed differences from both the alteration of the tissues and the regenerative potential.

Animal tissue-based quantitative comparison of dual-energy CT to SPR conversion methods using high-resolution gel dosimetry

Dual-energy computed tomography (DECT) has been shown to allow for more accurate ion therapy treatment planning by improving the estimation of tissue stopping power ratio (SPR) relative to water, among other tissue properties. In this study, we measured and compared the accuracy of SPR values derived using both dual- and single-energy CT (SECT) based on different published conversion algorithms. For this purpose, a phantom setup containing either fresh animal soft tissue samples (beef, pork) and a water reference or tissue equivalent plastic materials was designed and irradiated in a clinical proton therapy facility. Dosimetric polymer gel was positioned downstream of the samples to obtain a three-dimensional proton range distribution with high spatial resolution. The mean proton range in gel for each tissue relative to the water sample was converted to a SPR value. Additionally, the homogeneous samples were probed with a variable water column encompassed by two ionization chambers to benchmark the SPR accuracy of the gel dosimetry. The SPR values measured with both methods were consistent with a mean deviation of 0.2%, but the gel dosimetry captured range variations up to 5 mm within individual samples.Across all fresh tissue samples the SECT approach yielded significantly greater mean absolute deviations from the SPR deduced using gel range measurements, with an average difference of 1.2%, compared to just 0.3% for the most accurate DECT-based algorithm. These results show a significant advantage of DECT over SECT for stopping power prediction in a realistic setting, and for the first time allow to compare a large set of methods under the same conditions.

Heavy metal (PTE) ecotoxicology, data review: Traditional vs. a compositional approach

Potentially Toxic Elements (PTEs) otherwise known as heavy metals are ubiquitous in soils and can have a range of negative health and environmental impacts. In terrestrial systems understanding how PTEs move in the environment is made challenging by the complex interactions within soil and the wider environment and the compositional nature of PTEs. PTEs are compositional because data of individual PTEs within in a sample are ratios which may be under a sum constraint, where individual components sum up to a whole. In this study three different scenarios were considered, one using the centred log ratio transformation (clr) a compositional transformation, the more “traditional” log10 transformation (log10) and untransformed data acting as a comparison (unt) were applied to four different datasets. Three were the Liver, Muscle and Kidney tissue of Eurasian Badgers (Meles meles) and the fourth was soil and data were extracted from a regional geospatial survey. Cluster analysis demonstrated that the clr and log10 transformation were able to resolve compositional trends at the point of the individual sample, whilst unt could not and did not meet the preconditions for the next phase of analysis. At the level of compositional trends between PTEs complex heatmaps demonstrated that clr was able to isolate PTE relationships and highlight commonalities between different datasets, whilst log10 could not. In the final phase, principal component analysis (PCA) of the clr transformation showed similarities between the signals in the soft tissues and the disparities they had with soil, whilst the log10 transformation was unable to achieve this. Overall, the clr transformation was shown to perform more consistently under a variety of analytical scenarios and the compositional approach will provide more realistic interpretations about PTEs in both soil and animal soft tissue than the log10 or unt conditions.

Impact of medical titanium implant surface on the efficiency of fibrointegration

The aim of this study was to study the effect of surface branching of titanium endoprostheses on the efficiency of fibrointegration. The object of the study was samples of titanium alloy Ti6Al4V in the form of disks with a diameter of 5 mm and a thickness of 1 mm with various surface treatments: 1) samples with a rough surface after sandblasting; 2) samples with a rough surface after sandblasting with a bioactive coating of titanium dioxide TiO2 with anatase structure. The study of surface roughness was carried out by profilometry. Evaluation of the spreading and proliferation of cells on the surface of test samples, as well as evaluation of the effectiveness of fibrointegration was carried out according to standard methods using scanning electron microscopy. During the experiments, mesinchymal stem cells were sown on test samples and the test samples were introduced into the soft tissues of experimental animals. Based on the results obtained, it was concluded that the technology of forming rough surfaces by sandblasting does not provide high uniformity and reproducibility in the nanometer range and, apparently, another method for obtaining a rough surface should be chosen. The application of a bioactive coating of titanium dioxide TiO2 with the anatase structure to the surface of titanium endoprostheses increases the efficiency of fibrointegration, however, primarily the fibrointegration of titanium endoprostheses depends on their surface roughness, which determines the concentration of cell structures, the intensity of their adhesion and the ability to fibrointegrative process.

Complete Genome Sequence of Human Oral Phylogroup 1 Treponema sp. Strain OMZ 804 (ATCC 700766), Originally Isolated from Periodontitis Dental Plaque

Host-associated treponeme bacteria play etiological roles in human and animal soft tissue infections. Treponema sp. strain OMZ 804 (ATCC 700766) was isolated from dental plaque sampled from a patient with periodontitis in Switzerland in 1994. We report here the complete genome sequence of its 2.98-Mb circular chromosome.

Relationship between geochemical environments, nutritional resources, and faunal succession in whale-fall ecosystems

Faunal succession in whale-fall communities is closely associated with the progress of decomposition of the whale carcass. The main nutritional resources supporting a whale-fall community change from whale matter to chemosynthetic products over time. To study the geochemical aspects of this nutritional succession, we sampled animals over time on and in sediments around carcasses of sperm whale Physeter macrocephalus in Sagami Bay (mobile scavenger to early sulfophilic stage) and off Cape Nomamisaki (sulfophilic stage), Japan (500 and 200-300 m water depths, respectively). In these 2 areas, stable carbon, nitrogen, and sulfur isotopes of the animal soft tissues were measured to precisely elucidate the nutritional resources for each animal. In Sagami Bay, mobile scavengers relied only on whale soft tissue. Infaunal animals at 2 wk after the deployment relied only on whale soft tissue, while infauna at 9 mo after the deployment relied on chemosynthetic products. Such changes in nutritional resources were consistent with the transition of the geochemical environment in the sediments. Off Cape Nomamisaki, vigorous microbial sulfate reduction and thioautotrophic primary production nourished the fauna around the carcasses. The fauna in this area consisted of chemosymbiotic bivalves and necrophagous animals with sulfide-tolerant metabolism. We conclude that the changes in microbial processes, biomass, and compositions in sediments influence faunal succession in whale-fall ecosystems via change in the available nutrition for the fauna.

Effect of t-ZrO2-Based Ceramic Samples on the Condition of Muscular and Connecting Tissues in Experimental Animals with Intramuscular Introduction

A highly dispersed powder (9–10 nm) based on a tetragonal solid solution of partially stabilized zirconia (t-ZrO2) was synthesized by coprecipitation of hydroxides from salt solutions. On the basis of this powder, nanocrystalline ceramic (grain size 60–70 nm) with high physicochemical and mechanical characteristics was obtained: degree of tetragonality c/a, 1.438–1.431; flexural strength, 900–1000 MPa; Vickers hardness, 13–14 GPa; crack resistance, 10–11 MPa m1/2. The ceramic implant obtained was placed into bodies of experimental animals. The response of soft tissues of experimental animals to the introduction of zirconia-based ceramic plates was investigated. The studies showed no toxic effect of the t-ZrO2-based ceramic implant on the tissues surrounding the implant and the organism of laboratory animals in the period from 30 to 195 days from the moment of implantation. The results of in vivo studies suggest that the obtained nanoscale bioceramic can be used in restorative dentistry and endoprosthetics as dental implants, endoprostheses, and bone fragments for transplantology.

Effect of the Surface of Medical Titanium Endoprostheses on the Efficiency of Fibrointegration

Titanium alloys approved for clinical application are used to manufacture various endoprostheses. Engraftment of the implant in bone tissue (osseointegration) is characterized by direct contact and functional connection between the implant and the bone tissue. The process of implant engraftment in soft tissue is characterized by fibrointegration, i.e., interaction between the endoprosthesis material and soft tissue; as a result, connective tissue having a fibrous structure is formed on the endoprosthesis surface. The process of the engraftment of titanium implants greatly depends on the properties of the implant surface; therefore, to improve the efficiency of fibrointegration, various methods for modifying the implant surface are designed to impart them with the necessary biomedical properties. Implants with a polished surface, with surfaces of varying degrees of roughness, as well as those coated with titanium dioxide with the anatase structure are considered. The use of atomic force microscopy, scanning electron microscopy, and profilometry in studies of mesenchymal stem-cell adhesion and in vitro studies of implants with differently treated surface, which were embedded into the soft tissues of experimental animals, made it possible to determine the requirements for the optimal surface treatment of titanium implants used in maxillofacial surgery.

Microplastic in wild populations of the omnivorous crab Carcinus aestuarii: A review and a regional-scale test of extraction methods, including microfibres

Microplastic (MP) has become ubiquitous in the marine environment. Its threat to marine organisms has been demonstrated under laboratory conditions, yet studies on wild populations still face methodological difficulties. We reviewed the methods used to separate MP from soft animal tissues and highlighted a lack of standardised methodologies, particularly critical for synthetic microfibres. We further compared enzymatic and a potassium hydroxide (KOH)-based alkaline digestion protocols on wild crabs (Carcinus aestuarii) collected from three coastal lagoons in the north Adriatic Sea and on laboratory-prepared synthetic polyester (PES) of different colour and polypropylene (PP). We compared the cost-effectiveness of the two methods, together with the potential for adverse quantitative or qualitative effects on MP that could alter the capability of the polymers to be recognised via microscopic or spectroscopic techniques. Only 5.5% of the 180 examined crabs contained MP in their gastrointestinal tracts, with a notably high quantitative variability between individuals (from 1 to 117 particles per individual). All MP found was exclusively microfibres, mainly PES, with a mean length (±SE) of 0.5 ± 0.03 mm. The two digestion methods provided comparable estimates on wild crabs and did not cause any visible physical or chemical alterations on laboratory-prepared microfibres treated for up to 4 days. KOH solution was faster and cheaper compared to the enzymatic extraction, involving fewer procedural steps and therefore reducing the risk of airborne contamination. With digestion times longer than 4 days, KOH caused morphological alterations of some of the PES microfibres, which did not occur with the enzymatic digestion. This suggests that KOH is effective for the digestion of small marine invertebrates or biological samples for which shorter digestion time is required, while enzymatic extraction should be considered as alternative for larger organisms or sample sizes requiring longer digestion times.

Attenuation Coefficients of the Individual Components of the International Electrotechnical Commission Agar Tissue-Mimicking Material

Tissue-mimicking materials (TMMs) are widely used in quality assurance (QA) phantoms to assess the performance of ultrasound scanners. The International Electrotechnical Commission (IEC) defines the acoustic parameters of up to 10MHz. To manufacture a TMM that closely mimics the acoustical properties of small animal soft tissue at high frequencies, the acoustic properties of each of the individual component ingredients used in the IEC agar-TMM recipe need to be quantified. This study was aimed at evaluating whether the overall attenuation coefficient of the IEC agar-TMM is the linear sum of the attenuation coefficients of each of its ingredients. Eight batches of agar-based materials were manufactured with different combinations of ingredients from the IEC agar-TMM recipe. The percentage concentration of each ingredient used in the individual mixes was identical to that specified in the IEC recipe. The attenuation of each of these batches was measured over the ultrasound frequency range 12–50MHz, and the attenuation value of the agar component was subtracted from the attenuation values of the other batches. Batch attenuation values, representing the attenuation of individual components within the IEC agar-TMM, were then summated and yielded attenuation values that accurately reproduced the attenuation of the IEC agar-TMM. This information forms a valuable resource for the future development of TMMs with acoustic properties similar to those of soft tissue at high frequencies.