Analytical, stochastic and experimental solution of the osteosynthesis of the fifth metatarsal by headless screw

This paper evaluates the various approaches to strength and stiffness analysis of fracture osteosynthesis using a headless Herbert screw. The problem has been extensively addressed using several scientific approaches, namely the analytical approach, stochastic approach, experimental approach, and (marginally) using the finite elements method. The problem is illustrated on the use of a prototype headless screw Ti: 4.0/1.4 x 30/7 (manufacturer: Medin, Czech Republic) and the surgical treatment of the fifth metatarsal fracture. Mathematical equations for the analytical calculation of the maximum stresses in the screw were established for tensile/compression loading. This problem is also interesting because of its static indetermination in tension and compression; for this reason, it was necessary to use the deformation condition, i.e., the relationship between screw extension and bone contraction. The stochastic (probabilistic) approach, i.e., application of the Monte Carlo method, takes advantage of the mathematical equations derived during the analytical solution by respecting of the natural variabilities and uncertainties. The analytical and stochastic approaches were validated by measurements on porcine bones and by the finite element method. The data measured experimentally were also processed and used for deriving an equation, appropriately approximating the data. The main part of the measurement was to determine the axial force generated during osteosynthesis with a headless screw. The obtained compressional force was used to determine the maximal stress in the screw and bone. Finally, the methods were compared. In this paper, comprehensive and original approaches based on the authors' experience with multiple methods are presented. Obtained results are necessary for headless screw designers during optimalization of the implants and are also useful for surgeons developing new surgical techniques. This biomechanical problem was solved in cooperation with the engineering industry and physicians to improve the quality of care for patients with trauma in orthopedics and surgery.Web of Science1219art. no. 961

Reasons for placement of children into constitutional care in Znojemsko

Téma práce spadá do oblasti sociálně-právní ochrany dětí. V jejím obsahu jsou uvedeny základní pojmy a definice této problematiky a dále je zde také vymezena typologie rodičů dětí, jež jsou odebírány z rodin do ústavů, a typologie situací v těchto rodinách. To vše na základě srovnání spisových dokumentací oddělení sociálně-právní ochrany dětí a mládeže Městského úřadu ve Znojmě.Katedra věd o výchověDokončená práce s úspěšnou obhajobo

Imunohistochemický průkaz mastocytů a dendritických buněk v periprotetických tkáních asepticky uvolněných endoprotéz

PURPOSE OF THE STUDY This study deals with the possibilities and application of immunohistochemical methods to detect mast and dendritic cells in periprosthetic tissues in patients with aseptically loosened total joint replacements of the knee and hip. The purpose of the study was to quantify and characterize the distribution of mast and dendritic cells in the examined samples and to study the statistically significant relations between the aforementioned cell populations and selected parameters characterizing the patients, implants or tissue response. Based on the proved findings, a possible relation between mast and dendritic cells and histomorphological patterns of aseptic loosening and the benefit of the applied immunohistochemical methods was evaluated. MATERIAL AND METHODS Periprosthetic tissues from a total of 31 patients (17 patients after a revision surgery of hip prosthesis, 14 patients after a revision surgery of knee prosthesis) were examined. The collected samples were processed according to the standard protocol for the purposes of histological and immunochemical examination. Antibodies against tryptase and CD117 were used for immunohistochemical detection of mast cells. Dendritic cells were detected by means of S100 and CD1a antibodies. Quantification of both the cell populations was carried out by optical microscopy in 20 high power fields at 400-times magnification. From among the applied methods we picked the more sensitive one for statistical evaluation. It was tryptase in the case of mast cells and S100 in the case of dendritic cells. RESULTS Mast and dendritic cells were mostly distributed dispersively in periprosthetic tissues; however, they also occurred in groups perivasally or near necrotic parts. The examined samples showed the presence of 60 mast cells and 50 dendritic cells on average. The increased density of mast and dendritic cells was associated with polypously formed pseudosynovium and cement fixation of prostheses; this relation was statistically significant. It was impossible to prove the correlation between the quantity of the observed cell populations and the nature and the number of the observed particles because wear particles were present dispersely in all the samples. Another statistically significant relation to the type of material or implant fixation or other examined histomorphological patterns was not proved. A strong density of mast cells with a minimum presence of dendritic cells was observed in the control patient group. DISCUSSION The differences in density of S100 positive dendritic cells between the control and examined group of patients can be caused by the activation of dendritic cells by exogenous or endogenous pathways of immune processes going on after the implantation of endoprosthesis. The statistically significant interrelation of mast cells, polypously formed pseudosynovium and cement wear particles can be explained at least in part as a tissue reaction induced by cement particles. CONCLUSIONS We proved the presence of two immunologically significant cell populations in periprosthetic tissues. The said findings indicate a conclusion of significant functional participation of mast and dendritic cells in pathogenesis of aseptic loosening and periprosthetic osteolysis. Nevertheless, this will have to be proved in another way and with the use of another method.Web of Science85535835

Histological analysis of retraction pocket pars tensa of tympanic membrane in children

Aims: Histological and histochemical analysis of retraction pocket of pars tensa of tympanic membrane in children. Identification of morphological abnormalities in comparison with a healthy tympanic membrane as it is described in standard textbook. Identification of signs typical for cholesteatoma and support for a retraction theory of cholesteatoma formation. Study design: A prospective study analysing 31 samples of retraction pockets taken during surgery. Departments: University Hospital, Children’s Medical Centre Methods: Samples of retraction pockets were processed by a standard process for light microscopy, stained by haematoxylin-eosin. Van Gieson’s stain was used for differential staining of collagen, Verhoeff’s stain for elastic fibre tissues, Alcian blue for acidic polysaccharides and PAS (Periodic Acid Schiff) method for basement membrane polysaccharides. Results: The following findings were observed in the samples of retraction pockets: hyperkeratosis (100%), hypervascularisations (100%), subepithelial fragmented elastic fibres (96%), myxoid changes (87%), subepithelial inflammatory infiltration (84%), rete pegs (71%), papilomatosis (71%), intraepithelial inflammatory cellularizations, (48%), intraepithelial spongiosis (16%) and parakeratosis (3%). No basement membrane continuity interruptions were observed. Thickness of retraction pocket, thickness of epidermis, occurrence of rete pegs and frequency of fragmented elastic fibres was higher in a Grade III stage RP than Grade II stage RP (according to Charachon). Conclusion: Morphological abnormalities in the structure of retraction pockets in comparison with a healthy tympanic membranewere described. The changes are typical for a structure of cholesteatoma (these changes are common in matrix and perimatrix), supporting retraction theory of its origin. Our observations show that it is inflammation that probably plays a key role in the pathogenesis of retraction pocket. The frequency of some of the changes increases with the stage of retraction pocket (II–III according to Charachon). Basement membrane continuity interruptions are not typical for retraction pockets.Web of Science8621721

Laryngopharyngeal Reflux Is a Potential Risk Factor for Juvenile-Onset Recurrent Respiratory Papillomatosis

Introduction. Human papillomavirus (HPV) causes juvenile-onset recurrent respiratory papillomatosis (JORRP). Although HPV is common in children, the prevalence of JORRP is low. It is likely that other factors contribute to the pathogenesis of JORRP, during either activation or reactivation of a latent HPV infection. There is evidence that laryngopharyngeal reflux (LPR) might be such a risk factor for adult-onset recurrent respiratory papillomatosis. This study investigated if LPR might also be a risk factor for JORRP. Materials and Methods. Children with JORRP of the larynx that required microlaryngoscopy at a tertiary referral hospital were included in this prospective case-series study from November 2015 to November 2017. Using immunohistochemistry, HPV infection and pepsin associated with LPR were diagnosed from laryngeal biopsies. Results. Eleven children (aged 4-14 years) were analyzed. No patient had a history of immunodeficiency or tobacco smoke exposure. All patients underwent at least three previous surgeries due to JORRP and had been vaccinated against HPV in the past. Five children were treated using antivirotics and immunomodulators. The only known maternal risk factor was that three mothers were primiparous. All 11 samples were infected with HPV (type 6 or 11). Pathologic LPR was diagnosed in 5/11 children (45.5%). Conclusion. LPR may be a risk factor for JORRP, contributing to its development by activating or reactivating a latent HPV infection. Results are in accordance with those from our previous study in adults

Loss of PTEN Facilitates Rosiglitazone-Mediated Enhancement of Platinum(IV) Complex LA-12-Induced Apoptosis in Colon Cancer Cells.

We demonstrated for the first time an outstanding ability of rosiglitazone to mediate a profound enhancement of LA-12-induced apoptosis associated with activation of mitochondrial pathway in human colon cancer cells. This effect was preferentially observed in the G1 cell cycle phase, independent on p53 and PPARγ proteins, and accompanied with significant changes of selected Bcl-2 family protein levels. Further stimulation of cooperative synergic cytotoxic action of rosiglitazone and LA-12 was demonstrated in the cells deficient for PTEN, where mitochondrial apoptotic pathway was more stimulated and G1-phase-associated dying was reinforced. Our results suggest that combined treatment with rosiglitazone and LA-12 might be promising anticancer strategy in colon-derived tumours regardless of their p53 status, and also favourable in those defective in PTEN function

Rosiglitazone-mediated sensitization of HCT116 cells to LA-12-induced apoptosis.

<p>(a) Percentage of apoptotic (annexin V positive/propidium iodide negative, flow cytometry) HCT116 wt cells and (b) cleavage of caspase-3 and PARP (Western blotting) following pretreatment (24 h) with rosiglitazone (RGZ, 50 μM) and subsequent treatment (48 h) with LA-12 (0.75 μM), in the absence (DMSO) or presence of z-VAD-fmk (10 μM). (c) Percentage of apoptotic (annexin V positive/propidium iodide negative, flow cytometry) RKO or DLD1 cells following pretreatment (24 h) with rosiglitazone (RGZ, 50 μM) and subsequent treatment (48 h) with LA-12 (0.75 μM). Results are means + S.E.M. or representatives of three independent experiments. Statistical significance: P < 0.05, * versus control, ‡ versus RGZ, Ο versus LA-12, and Δ for with/without z-VAD-fmk.</p

<i>A potential involvement of PPAR</i>γ <i>in apoptosis induced by combination of rosiglitazone and LA-12</i>.

<p>(a) Cleavage of caspase-9, caspase-3, PARP (Western blotting), and (b) caspase-3 activation (flow cytometry) in HCT116 wt cells transfected (24 h) with control or PPARγ siRNA, treated (24 h) with rosiglitazone (RGZ, 50 μM) and subsequently incubated (48 h) with LA-12 (0.75 μM). Results are means + S.E.M. of three independent experiments. Statistical significance: P < 0.05, * versus control, ‡ versus RGZ, Ο versus LA-12.</p

The role of p53 and Chk2 proteins in rosiglitazone-mediated enhancement of LA-12-induced apoptosis.

<p>Cleavage of caspase-9, caspase-3, PARP and the level of Chk2 and p53 proteins in HCT116 wt, Chk2-/- and p53-/- cells pretreated (24 h) with rosiglitazone (RGZ, 50 μM), and subsequently treated (48 h) with LA-12 (0.75 μM), detected by Western blotting. Results are representatives of three independent experiments.</p

Involvement of mitochondria in cooperative cytotoxic action of rosiglitazone and LA-12.

<p>(a) The release of cytochrome c into the cytoplasm (cytoplasmic fraction) of HCT116 cells pretreated (24 h) with rosiglitazone (RGZ, 50 μM) and subsequently treated (48 h) with LA-12 (0.75 μM), detected by Western blotting after cell fractionation. (b) Cleavage of caspase-9, PARP, Bax protein level (Western blotting), and (c) changes in mitochondrial membrane potential (MMP, flow cytometry) in HCT116 wt and Bax-/- cells treated as in a). (d) The level of Noxa, Bim, Puma, Bid, Bax and Bak protein (Western blotting) in HCT116 wt cells treated as in a). Results are means + S.E.M. or representatives of three independent experiments. Statistical significance: P < 0.05, * versus control, ‡ versus RGZ or Ο versus LA-12, and Δ for wt versus Bax-/- cells.</p