[Mechanical Testing of Tendons Sutured with Newly Developed Biomaterial]. / Mechanické testování slach po suture nove vyvinutým biomateriálem.

PURPOSE OF THE STUDY Tendon injuries continue to be a highly topical issue. Research and clinical activities in this area aim to achieve an optimal repair of the damaged tendon. Such suture is characterised by maximum tensile strength, resistance to gapping at the repair site, preservation of smooth surface, prevention of adhesions and facilitation of fast rehabilitation and active tendon movement. The suture as such is required to show mechanical resistance in particular. Considered optimal is the use of core suture of the tendon in combination with epitendinous suture. The group of researchers has for several years already been exploring new materials. They can contribute to better balance between adequate mechanical strength of the suture and biological support of healing. MATERIAL AND METHODS The study was carried out as an ex vivo experiment on porcine tendon models. A tendon segment was obtained from slaughtered animals and a total rupture of the tendon was imitated by sharp cutting of its central portion. Subsequently, the tendon was repaired by Adelaide suture using coated braided polyester (Ethibond) and two types of new polyamide 6 based (PA6) sutures. The first suture was designed as an unabsorbable polyester core (PES silk) surrounded by absorbable PA6 nanofibres. The second suture was created by braiding a PES silk yarn and two viscose yarns with PA6 nanofibres into a composite surgical suture. As a part of the study also examined was the tensile strength of suture with the use of other stitches, effect of the shape of the needle s point on the tensile strength of the suture and the effect of secured mattress peritendinous suture. The tensile strength of the suture was tested until failure and the achieved maximum load was monitored. RESULTS The PES core yarn with PA6 nanofibre braiding showed lower tensile strength (28.5 ± 5.2 N) than the yarn braided from one PES yarn and two viscose yarns with PA6 nanofibres (45.7 ± 6.7 N). Both newly developed sutures, however, fail to achieve the tensile strength of Ethibond (100.3 ± 19.1 N). In case of Ethibond suture using various types of stitches, the lowest tensile strength was observed in McLarney 4-strand core suture (68.8 ± 18.7 N). A higher tensile strength was achieved by Adelaide 4-strand core suture (83.6 ± 11.2 N). The highest tensile strength was seen in 6-strand core Savage suture (147.4 ± 22.7 N). When the effect of the type of needle was tested, a statistically significant difference between the taper point needle (72.0 ± 7.0 N) and reverse cutting needle (63.3 ± 9.6 N) was observed. In case of McLarney suture the epitendinous stitch increased the tensile strength by 46.2% and in case of Adelaide suture by 48.3%. CONCLUSIONS For tendon core suture, the use of sutures with multiple longitudinal segments seems more appropriate. The epitendinous suture can considerably reinforce the basic load-bearing core suture. Also observed was not an insignificant effect of the needle profile on the resulting tensile strength of the suture. In materials developed by us, more suitable seems to be the design of braiding of absorbable nanofibers with a load-bearing non-absorbable yarn. While the mechanical tensile strength of new materials is lower, the benefits are expected in the form of biological support of healing. Moreover, the nanofibers can be used as a carrier of biological and therapeutic substances. Further improvement of mechanical properties of the newly developed biomaterial can be foreseen if the material of the load-bearing non-absorbable yarn is changed or the load-bearing yarn and nanofibres ratio modified. This pilot study shall use the findings for further development and modification of new materials in basic research and shall also verify the biological aspects and the course of healing in in vivo studies. Key words: tendon, suture, pig, biomaterials, nanofibres, mechanical testing, healing, polyester, Adelaide.

[Canine Elbow Humeroulnar Incongruity Measurements Using Computed Tomography]. / Merení humeroulnární inkongruity loketního kloubu u psu pomocí výpocetní tomografie.

PURPOSE OF THE STUDY The purpose of the study is to compare the repeatability and reproducibility of quantitative and subjective evaluation of elbow humeroulnar incongruity (HUI) using computed tomography (CT) on an in vivo canine model. MATERIAL AND METHODS HUI was evaluated on canine (n = 50) elbow joints (n = 100). The computed tomography of elbow joints was performed under intravenous sedation. Multiplanar reconstructions (MPR) were produced. HUI was evaluated on sagittal MPR images subjectively and by measuring the subluxation index (SI). The SI was defined by measuring the distance between the centres of two circles, the shape of which corresponded the most with the shape of the trochlear notch of the ulna at sagittal crest and the shape of humeral trochlea. This distance was divided by the radius of the circle (r) defining the humeral trochlea. HUI was subjectively evaluated based on the width of the joint space at the greatest caudal convexity of the trochlear notch of the ulna. Three categories of HUI were established: 0 (congruent), 1 (moderately incongruent), 2 (strongly incongruent). Measurement and evaluation of HUI was conducted by two evaluators twice at a one-month interval between the first and second measurement. The statistical analysis was carried out using the repeated measures ANOVA and the Cohen s kappa coefficient. RESULTS The mean SI was 11.14 (SD 8.703). The SI values measured by two evaluators were statistically significantly different (p < 0.05). Contrarily, there was no statistically significant difference between the two measurements of the same evaluator (p > 0.05). The subjective evaluation of HUI done by two evaluators showed a mean to substantial agreement (Kappa = 0.53-0.79). There was a substantial to almost perfect agreement between the results of two evaluations carried out by a single evaluator (Kappa = 0.79-0.83). DISCUSSION The radiographic detection of moderate incongruity is unreliable, especially on account of wrongly positioned elbow joint, superposition of bone structures and due to the evaluation of three-dimensional bone structure through a two-dimensional image. Evaluation of humeroulnar congruity by computed tomography (CT) enables to assess the congruity of joints without the superposition of neighbouring bone structures. The quantification of humeroulnar incongruity using the SI does not show a higher degree of agreement between two evaluators as against the subjective evaluation of HUI. On the contrary, the agreement between two measurements of a single evaluator was high in both the cases. CONCLUSIONS Dog is a suitable model animal for evaluation of HUI of elbow joints due to frequent incidence of elbow dysplasia associated with HUI. The quantification of HUI at the expense of subjective evaluation of HUI is often overrated in radiological studies. Key words: dog, elbow, humeroulnar incongruity.

Antisenescence effect of REAC biomodulation to counteract the evolution of myelodysplastic syndrome.

About 30 percent of patients diagnosed with myelodysplastic syndromes (MDS) progress to acute myeloid leukemia (AML). The senescence of bone marrow?derived mesenchymal stem cells (BMSCs) seems to be one of the determining factors in inducing this drift. Research is continuously looking for new methodologies and technologies that can use bioelectric signals to act on senescence and cell differentiation towards the phenotype of interest. The Radio Electric Asymmetric Conveyer (REAC) technology, aimed at reorganizing the endogenous bioelectric activity, has already shown to be able to determine direct cell reprogramming effects and counteract the senescence mechanisms in stem cells. Aim of the present study was to prove if the anti-senescence results previously obtained in different kind of stem cells with the REAC Tissue optimization - regenerative (TO-RGN) treatment, could also be observed in BMSCs, evaluating cell viability, telomerase activity, p19ARF, P21, P53, and hTERT gene expression. The results show that the REAC TO-RGN treatment may be a useful tool to counteract the BMSCs senescence which can be the basis of AML drift. Nevertheless, further clinical studies on humans are needed to confirm this hypothesis.

Liquid resorbable nanofibrous surgical mesh: a proof of a concept.

BACKGROUND: Surgical mesh is widely used not only to treat but also to prevent incisional hernia formation. Despite much effort by material engineers, the 'ideal' mesh mechanically, biologically and surgically easy to use remains elusive. Advances in tissue engineering and nanomedicine have allowed new concepts to be tested with promising results in both small and large animals. Abandoning the concept of a pre-formed mesh completely for a 'pour in liquid mesh' has never been tested before. MATERIALS AND METHODS: Thirty rabbits underwent midline laparotomy with closure using an absorbable suture and small stitch small bites technique. In addition, their abdominal wall closure was reinforced by a liquid nanofibrous scaffold composed of a fibrin sealant and nanofibres of poly-ε-caprolactone with or without hyaluronic acid or the sealant alone, poured in as an 'onlay' over the closed abdominal wall. The animals were killed at 6 weeks and their abdominal wall was subjected to histological and biomechanical evaluations. RESULTS: All the animals survived the study period with no major complication. Histological evaluation showed an eosinophilic infiltration in all groups and foreign body reaction more pronounced in the groups with nanofibres. Biomechanical testing demonstrated that groups treated with nanofibres developed a scar with higher tensile yield strength. CONCLUSION: The use of nanofibres in a liquid form applied to the closed abdominal wall is easy to use and improves the biomechanical properties of healing fascia at 6 weeks after midline laparotomy in a rabbit model.

[Persisting symptoms, diastolic dysfunction and decreased coronary flow reserve after succesful correction of aortic recoarctation]. / Pretrvávajúce symptómy, diastolická dysfunkcia a nízka koronárna rezerva u pacientky po úspesnej korekcii rekoarktácie aorty.

We present a case of a 53-year-old woman undergoing successful surgical treatment ofcoarcation restenosis after patch grafting in childhood. Despite the optimal result of the operation, normal left ventricle systolic function and coronary angiogram, majority of symptoms, such as angina and dyspnea, persist 16 months after the intervention. In further investigation, pathological values of left ventricular end-diastolic pressure (LVEDP = 30 mm Hg) and coronary flow reserve (CFR = 1.3) were confirmed, implicating recoarctation to be the unusual cause of cardiac syndrome X.

PVA and PCL nanofibers are suitable for tissue covering and regeneration.

The aim of the study was to evaluate the safety and efficacy of a new therapeutic approach to skin defects resulting from split thickness grafting. Within the study, nanofiber-based dressings fabricated using polyvinyl alcohol (PVA) and poly-ε-caprolactone (PCL) were used, with different mass density. The study was performed in 1 female minipig. Nine defects (approx. 4x4 cm) were made in the superficial skin layer. The tested materials were applied to the squared skin defect and covered by a Jelonet paraffin gauze, sutured in the corners of the defects. The animal was monitored daily during the healing process (21 days). On day 5, 12, and 27, the healing of the wound was evaluated, and a biopsy was performed for further histologic testing. At the end of the study (on day 27 after the procedure), the animal was euthanized, and a standard pathologic evaluation was performed. We can conclude that the nanofiber scaffold which was well tolerated, could be used as a smart skin cover which could be functionalized with another bioactive substances directly on the surgeon table, among potential bioactive substances belong platelet derivatives, antibiotics, etc.

[Residual echocardiographic findings and NT-proBNP in asymptomatic adult patients after radical correction of Fallot's tetralogy]. / Reziduální echokardiografické nálezy a NT-proBNP u asymptomatických dospelých pacientu po radikální korekci Fallotovy tetralogie.

OBJECTIVE: Define the profile of NT-proBNP values in asymptomatic adult patients after radical correction of Tetralogy of Fallot (TOF) and identify links between possible increase in NT-proBNP and residual echocardiographic findings. METHODOLOGY: NT-proBNP samples were taken from and a detailed echocardiographic examination was performed in 21 adult stabilised patients after radical correction of TOF in childhood. The results were submitted for statistical analysis. RESULTS: The incidence of low values of the S wave < 11.5 cm/s of tricuspid anulus evaluated by tissue Doppler echocardiography (TDI) (P < 0.05) was significantly higher in patients with NT-proBNP > 125 pg/ml. All patients with impaired right ventricular diastolic filling evaluated by tissue Doppler echocardiography (E' / A' < 1 ) had higher values of NT-proBNP (NS). Other echocardiographic parametres did not show any dependence on NT-proNBP values, including the morphology or atrial defects in the right heart sections which are most conspicuous in an echocardiographic examination. CONCLUSION: Asymptomatic patients after radical correction of TOF have higher values of NT-proBNP (167.95 +/- 91.75 pg/ml). At the same time, the increase closely correlates with the detection of a global right ventricle systolic dysfunction evaluated by S (TDI). On the other hand, there is often no correlation between highly conspicuous changes in the morphology of the right heart compartments or residual or postincision defects of the pulmonary valve on the one hand and increased NT-proBNP on the other. The S measurement has the potential to become routine examination in patients after radical correction of TOF for timely detection of right ventricular systolic dysfunction. Precise prognostic and primarily therapeutic impact of the pathologic finding still needs to be determined.

[Location of the bundle of Kent in patients with Ebstein's anomaly of the tricuspid valve]. / Lokalizace Kentova svazku u pacientu s Ebsteinovou anomálií trikuspidální chlopne.

The prequisite of better therapeutic results in patients with Ebstein's anomaly of the tricuspid valve is more perfect diagnosis not only of the severity of the malformed valve but also of other associated defects incl. the anomalous accessory bundle of Kent which causes the development of dangerous tachydysrhythmias. The authors present their own experience with the localization of the bundle of Kent by mapping the endocardium of the atria in seven children before a cardiac operation. In all ventricular preexcitation type B with the bundle of Kent in the posterior lower portion of the atrial septum was found. In two non-operated patients who died with tachydysrhythmia which could not be controlled, the bundle of Kent was confirmed by histological examination, in three it was severed by operation, two patients are waiting to be operated. The authors recommend interruption of the bundle of Kent always concurrently with operation of the malformed tricuspid valve and other associated cardiac defects.

[Defects of the atrioventricular cardiac septum (persistent common atrioventricular canal)]. / Defekty atrioventrikulárního srdecního septa (canalis atrioventricularis communis persistens).

A new morphological-clinical classification was suggested for this type of heart malformations based on confrontation of authors' results with literature. The classification took into consideration appearance of the top of ventricular septum, form of atrioventricular valves, topography of the defect and its relation to the location of conducting system.

[Postoperative atrioventricular and intraventricular block in tetralogy of Fallot. Electrophysiology study]. / Pooperacní sínokomorové a nitrokomorové blokády u Fallotovy tetralogie, elektrofyziologická studie.

One of the causes of the late deaths after operations of the tetralogy of Fallot are dysrhythmias caused by impaired conduction and automatism. To assess the severity and site of the atrioventricular and intraventricular block the authors used in 19 patients after operation of the tetralogy of Fallot an invasive electrophysiological examination. The authors recommend, based on their own experience, to follow-up on a long-term basis all patients with temporary postoperative complete a-v block. The presence of bifascicular or temporary postoperative a-v block alone does not yet imply the need of a permanent pacemaker. If a serious a-v block persists after the third week or if a syncope or cardiac weakness develops, the authors indicate a permanent pacemaker. Also the development of trifascicular block, even in patients with a normal P-Q interval, detected during fever, physical work or during electrostimulation of the atria is an indication for the introduction of a permanent pacemaker.

[Ebstein's anomaly (a group of 47 patients)]. / Ebsteinova anomálie (soubor 47 nemocných).

In a group of 47 patients with Ebstein's anomaly followed up on a long-term basis the authors describe the natural course of the disease as well as contemporary diagnostic and therapeutic possibilities. The authors draw attention to typical symptoms of Ebstein's anomaly and emphasize the importance of early diagnosis by two-dimensional echocardiographic and Doppler examination and the introduction of individual conservative or surgical treatment.

[Pericardial teratoma in an infant]. / Teratom perikardu u kojence.

In a four-month-old neonate a pericardial teratoma was diagnosed which exerted pressure on the airways, right atrium and large blood vessels. The tumour was removed by operation. It was a simple, mature pericardial teratoma. Supporting cytostatic treatment was administered. Three years after operation the patient is free of signs of relapse of the tumour.

[Severance of the accessory bundle of Kent in a 13-year-old boy with Ebstein's anomaly of the tricuspid valve]. / Prerusení akcesorního Kentova svazku u 13-letého chlapce s Ebsteinovou anomalií trikuspidální chlopne.

In patients with Ebstein's anomaly of the tricuspid valve combined with WPW syndrome, possibly other cardiac disease, in particular with the repeated occurrence of severe tachydysrhythmias we can foresee cure or at least elimination of complaints by simultaneous surgical treatment of all defects. The author presents experience with the surgical treatment, the first of its kind in this country, in a boy aged 13 years. By better diagnosis it proved possible to locate correctly and to severe by surgery the abnormal accessory bundle between the right atrium and right ventricle, simultaneously with a plastic operation of the insufficient tricuspid valve with closure of the atrial septal defect. Since the operation the patient has no signs of ventricular preexcitation and has no tachydysrhythmias.

[Ebstein's anomaly of the tricuspid valve with the WPW syndrome]. / Ebsteinova anomálie trikuspidální chlopne s WPW-syndromem.

Case-history of a four-year-old boy with Ebstein's anomaly of the tricuspid valve with WPW syndrome. Severe tricuspid insufficiency and repeatedly occurring tachydysrhythmias soon led to cardiac decompensation and death before the intended cardiac operation. Non-invasive clinical, ECG, X-ray and ECHO examinations correlated with catheterization, electrophysiological and pathological findings. In addition to the dislocated, malformed tricuspid valve the septal cusp of which was fused with the ventricular septum the authors found another additional atrioventricular muscular connection between the lower part of the septum of the right atrium and right ventricle.