Interfascicular matrix-mediated transverse deformation and sliding of discontinuous tendon subcomponents control the viscoelasticity and failure of tendons.

In the present article, we investigated the sliding of discontinuous tendon subcomponents and the variation of nonhomogeneous deformation in the human Achilles tendon (AT) over time using uniaxial tensile and relaxation tests. The deformation and the resulting strain distribution under uniaxial tension are examined using a vision-based 3-D digital image correlation (DIC) system, which allows estimation of the strain field in the axial and lateral directions. Relaxation test under B-mode ultrasound imaging with the use of DIC method provides information about the local strain variation over time in the axial and anteroposterior directions. The observed nonhomogeneous deformation, a result from the twisted structure of the tendon, shows both compressive and tensile transverse strains that can generate interfascicular matrix (IFM) failure and initiate water accumulation in the course of tendinopathy. Moreover, using B-mode elastography with the DIC method, we have observed areas of low stiffness when the strain values exceed the strength limits, and this could correspond to IFM carrying the load between discontinuous tendon subcomponents. Thus, IFM carrying complex multiscale stresses may be responsible for the strength and viscoelastic properties of the AT. The results presented here reveal a new pathomechanism of AT failure. This could be useful in further studies on tendinopathy as well as effective planning of the AT therapy.

Influence of density and environmental factors on decomposition kinetics of amorphous polylactide - Reactive molecular dynamics studies.

In this work, we investigate the influence of the surrounding environment and the initial density on the decomposition kinetics of polylactide (PLA). The decomposition of the amorphous PLA was investigated by means of reactive molecular dynamics simulations. A computational model simulates the decomposition of PLA polymer inside the bulk, due to the assumed lack of removal of reaction products from the polymer matrix. We tracked the temperature dependency of the water and carbon monoxide production to extract the activation energy of thermal decomposition of PLA. We found that an increased density results in decreased activation energy of decomposition by about 50%. Moreover, initiation of decomposition of the amorphous PLA is followed by a rapid decline in activation energy caused by reaction products which accelerates the hydrolysis of esters. The addition of water molecules decreases initial energy of activation as well as accelerates the decomposition process. Additionally, we have investigated the dependency of density on external loading. Comparison of pressures needed to obtain assumed densities shows that this relationship is bilinear and the slope changes around a density equal to 1.3g/cm(3). The conducted analyses provide an insight into the thermal decomposition process of the amorphous phase of PLA, which is particularly susceptible to decomposition in amorphous and semi-crystalline PLA polymers.

The role of surgery in the treatment of colorectal metastases from primary skin melanoma.

AIM: The study assessed the role of colorectal surgery in the treatment of metastatic melanoma and identified patients who can most benefit from surgical resection. METHOD: A retrospective analysis was made of 34 consecutive patients with skin melanoma who underwent surgical resection of large bowel metastasis. RESULTS: The median disease-free interval between diagnosis of the primary and metastatic melanoma was 24 (7-98) months. Nine (27%) patients underwent emergency surgery for obstruction and 25 (73%) had an elective procedure. Resection with curative intent was performed in 14 (41%) and palliative resection in 20 (59%) patients. There was no postoperative mortality and morbidity occurred in 9%. The median survival following surgery was 11.5 (4-68) months. The 1-, 2- and 5-year survival rates were 50%, 32% and 17% respectively. Median survival was significantly increased in patients without extra-abdominal metastases, with no evidence of non-large-bowel metastases, if the disease-free interval was longer than 24 months and when curative resection was performed. In multivariate analysis, an apparently complete or palliative resection and the absence or presence of extra-abdominal metastases were the most important prognostic factors. CONCLUSION: An aggressive surgical approach to large bowel metastatic melanoma results in good palliation and effective relief of symptoms with acceptable morbidity and mortality.

[Factors inducing clinical symptoms of acute hepatic porphyria 1986-1990]. / Przyczyny indukujace objawy kliniczne ostrych porfirii watrobowych w latach 1986-1990.

The most frequent cause of porphyria attacks in this time period were drugs used in symptomatic treatment (in 69 out of 195 cases). In 42 women attacks were induced by sex hormone disturbances, in 21 cases by contact with paints and lacquer in 7 by alcohol and in 3 by calorie deficiencies. The main cause of porphyria attacks in carriers of this metabolic error is lack of porphyria considering in the differential diagnosis of abdominal pains, polyneuropathy and vague mental disorders, which leads to erroneous treatment worsening the course and prognosis of the disease.