Understanding frictional behavior in fascia tissues through tribological modeling and material substitution.

The objective of this study is to develop a reliable tribological model to enable a more thorough investigation of the frictional behavior of fascia tissues connected to non-specific lower back pain. Several models were designed and evaluated based on their coefficient of friction, using a low-frequency, low-load reciprocating motion. The study found that two technical elastomers, layered on PDMS to simulate the fascia and underlying muscle, are suitable substitutes for biological tissue in the model. The influence of tribopair geometry was also examined, and the results showed that greater conformity of contact leads to a lower COF, regardless of the material combination used. Finally, the friction properties of HA of various molecular weights and concentrations were tested.

Enzymatic Isolation, Amplification and Characterization of Dental Pulp Stem Cells.

The dental pulp represents an easily accessible source of adult dental pulp stem cells (DPSCs). The preferred approach to DPSC isolation is enzymatic digestion. However, the duration of the enzymatic activity is crucial. The purpose of this study was to isolate the DPSC populations using this method, characterize their biological properties and proliferation capacity, and to determine their ability to differentiate into mature cells. Before enzymatic digestion using 0.05% trypsin, we used the homogenization method in order to obtain a fine homogenate from the solid pulp tissue. The stem cells were cultivated in modified cultivation medium for mesenchymal adult progenitor cells containing 2% foetal bovine serum, growth factors and insulin-transferrin-selenium supplement. We were successfully able to isolate 10 populations of DPSCs. The vitality of DPSCs did not drop below 90 %. However, the DPSCs showed a significant decrease in the relative telomere length number with increasing passaging (P < 0.05). Isolated DPSCs highly expressed the CD markers: CD29, CD44, CD90, CD13, CD73 and CD166. In contrast, CD markers CD31, CD106, CD34 and CD45 were negative or low positive. We confirmed the high osteogenic and chondrogenic potential of the isolated stem cells. Isolated DPSCs did not show signs of cell degeneration or spontaneous differentiation during the entire cultivation. In addition, we were able to shorten the enzyme activity duration, and we were the first to demonstrate trypsin as the enzyme used for the enzymatic digestion method with the viability over 90 % of isolated DPSCs using this method.

The Differentiation Potential of Human Natal Dental Pulp Stem Cells into Insulin-Producing Cells.

Mesenchymal stem cells have the ability to differentiate into insulin-producing cells, raising the hope for diabetes mellitus treatment. The aim of this research was to study the ability of stem cells from discarded natal teeth to differentiate into insulinproducing cells. Two vital human natal teeth were obtained from a healthy 2-day-old female. Stem cells from the dental pulp were isolated, cultured under xenogenic-free conditions, propagated and characterized. Proliferative activity, population doubling time and viability were measured, and the multipotent differentiation ability was investigated. A twostep protocol was used to induce the human natal dental pulp stem cells to differentiate into insulinproducing cells. Phenotypic analysis was done using flow cytometry. Immunohistochemistry was performed to detect insulin and C-peptide. PDX1, HES1 and Glut2 gene expression analysis was performed by quantitative reverse transcription-polymerase chain reaction. Human natal dental pulp stem cells were able to undergo osteogenic, chondrogenic and adipogenic differentiation upon exposure to the specific differentiation media for each lineage. Their differentiation into insulin-producing cells was confirmed by expression of C-peptide and insulin, as well as by 975.4 % higher expression of PDX-1 and 469.5 % higher expression of HES1 in comparison to the cells cultivated in standard cultivation media. Glut2 transporter mRNA was absent in the non-differentiated cells, and differentiation of the stem cells into insulin-producing cells induced appearance of the mRNA of this transporter. We were the first to demonstrate that stem cells obtained from the pulp of natal teeth could be differentiated into insulinproducing cells, which might prove useful in the stem cell therapy for type 1 diabetes.

Proliferative Capacity and Phenotypical Alteration of Multipotent Ecto-Mesenchymal Stem Cells from Human Exfoliated Deciduous Teeth Cultured in Xenogeneic and Allogeneic Media.

Foetal calf serum (FCS) is a standard supplement used in media for in vitro stem cell cultivation. This xenogeneic supplement remains widely used for its favourable growth-promoting properties and ease of accessibility; however, it is inherently not fit for human medicine due to its capacity to temper with the cultured cell quality. For this reason, the international community encourages research and development of allogeneic sera, which would expunge this issue. This study aims to investigate the differences in proliferative capacity, phenotype, and differentiation capacity of ecto-mesenchymal stem cells from human exfoliated deciduous teeth (SHED) cultured in vitro in media supplemented with allogeneic and xenogeneic sera. To address these aims, we cultured three lineages of stem cells in media supplemented with FCS in a concentration of 2% + growth factors; human blood plasma and platelet-rich plasma in concentrations of 2% + growth factors, and 10%. Here, the xenogeneic cultivation was considered as a basis for comparison because this serum is commonly used in studies concerning ecto-mesenchymal stem cells. The study shows that multipotent ecto-mesenchymal SHED can be feasibly cultivated in media where the xenogeneic FCS is substituted by allogeneic platelet-rich plasma, considering the cultured cell proliferative and differentiation capacities. We have also proved that different sera impact the cultured cells' phenotype differently, which has major implications for previous and future stem cell research and regenerative therapy.

Ionizing radiation induces senescence and differentiation of human dental pulp stem cells.

Head and neck cancer is one of the most common cancers in Europe. Many current anti-cancer treatments, including ionizing radiation, induce apoptosis via DNA damage. Unfortunately, such treatments are non-selective to cancer cells and produce similar toxicity in normal cells, including adult stem cells. One of the fundamental properties of an adult stem cell is that it does not have any tissue-specific structures that allow it to perform specialized functions. However, under certain stimuli, unspecialized adult stem cells can give rise to specialized cells to generate replacements for cells that are lost during one's life or due to injury or disease. Nevertheless, specialization of stem cells must be controlled by specific milieu and also initiated at the proper time, making the entire process beneficial for tissue recovery and maintaining it for a long time. In this paper we assess whether irradiated dental pulp stem cells have maintained open their options to mature into specialized cells, or whether they have lost their unspecialized (immature) state following irradiation. Our findings showed radiation-induced premature differentiation of dental pulp stem cells towards odonto-/osteoblast lineages in vitro. Matrix calcification was visualized from Day 6 or Day 9 following irradiation of cells expressing low or high levels of CD146, respectively.

Forensic odontologists successfully identify tsunami victims in Phuket, Thailand.

More than a year has elapsed since the seaquake in South-East Asia in December 2004, and more than 92% of the non-Thai victims have been identified. About 80% of the non-Thai victims were identified by dental information. This high success rate of dental identification in Thailand was a matter of surprise for many forensic experts. Identification based on dental information is a highly efficient, reliable and rapid procedure. The conclusions drawn from the identification of tsunami victims in Thailand were recently discussed at the 17th Meeting of the Standing Committee on Disaster Victim Identification of Interpol in Lyon, and may be used to formulate new guidelines for the identification of victims.

Sliding properties of plasma assisted CVD CNchi coatings for metal bioimplants.

Coatings of CNchi, have been prepared on the substrates of material Ti6Al4V, of which the human joint replacements are made. The deposition of the CNchi coating was carried out by PACVD method in apparatus with standard arrangement. The methane and nitrogen have been used as precursors for CNchi compound. The infrared absorption spectroscopy and Rutherford backscattering spectroscopy were applied on diagnostics of prepared CNchi layer. Beside carbon and nitrogen the hydrogen and oxygen were found in the coatings. The sliding tests were carried out with the samples. The counter parts were the cylinders made of the polyethylene of the same type as for big joint prostheses is used. The tests were carried out in the medium of physiological solution. The CNchi coatings perform well under the lower load of 25 and 50 N. When the load is increased to 100 N, the friction coefficient slowly increases, but measured values of mu are typical for boundary lubrication.

Influence of electrodes arrangement on the quartz resonator equivalent circuit.

The strip electrodes deposited on the main surfaces of the rotated Y-cut quartz plate in the Z' direction and overlapping only in the central part of the plate excite a non-negligible electric field parallel to the surface of the plate. The influence of this field on the parameters of the electrical equivalent circuit and frequency-temperature characteristic of the AT-cut quartz plates is examined. The influence of this electric field parallel to the surface depends on the orientation of electrodes in the rectangular coordinate system of quartz.

Control and driving of pneumatic total artificial hearts TNS-BRNO-II and -III in long-term experiments.

Hemodynamic analysis was carried out during long-term experiments with the pneumatic total artificial hearts TNS-BRNO-II and TNS-BRNO-III to determine standard methods of starting artificial hearts and criteria for their long-term operation in vivo. In long-term experiments, regulatory mechanisms automatically regulating the systole length and diastolic aspiration pressure have also been verified. Comparison of hemodynamic variables obtained from invasive measurements with pneumatic pressure curves permitted the control and monitoring of the experiment in its entirety by noninvasive methods only. The control of the artificial heart using the Chirasist TN 3 and Chirasist TN 4 was adapted to specific properties of the pumps, above all to the functions of the atypical inlet valves. The terminal stages of the experiments have shown that a 100-ml pump can ensure survival of experimental calves up to 210 kg body weight.