Background: Achilles tendon ruptures are characterized by a long recovery period, high re-rupture rate and late return to work. To overcome these difficulties and augment tendon repair, many agents have been used. Aims: To determine the effect of autologous platelet rich plasma (PRP) in the treatment of Achilles tendon ruptures in rabbits. Study Design: Animal experimentation. Methods: The study included 14 New Zealand albino rabbits that were divided randomly into 2 groups, A and B, each containing seven rabbits. On day zero, all 28 Achilles tendons were tenotomized and repaired. In group A, the tendons were injected with PRP post-surgery, whereas those in group B were left untreated. On day 28, the right tendons in both groups were examined histopathologically via both light and electron microscopy, and the left tendons were subjected to biomechanical testing. Results:The histological and biomechanical findings in both light and electron microscopy in group A were better than those in group B, but the difference was not significant. According to Tang's scale, the mean value in Group A was 3.57, while it was 3.0 in Group B. The mean value of Group A for the length of collagen bands was 48.09 nm while the mean value of Group B was 46.58 nm (p=0.406). In biomechanical tests, although stiffness values were higher in group A, the difference between groups was not significant. In addition, maximum load values did not differ between groups A and B. Conclusion: PRP had no effect on the healing process 28 days post-Achilles tendon rupture.

Amaç: Bu çalışmada lomber omurganın rijit tespitinden sonra komşu segmentin hareket genişliği ve stabilitesi araş-tırıldı. Gereç ve yöntemler: Bu çalışmada 17 taze donmuş kuzu lomber omurgası (sakrum T 12 'yi içeren) kullanıl-dı. Biyomekanik test aksiyel kompresyon test cihazı ile yapıldı. Aksiyel kompresyon tüm numunelere 5 mm/dk. yükleme hızı ile uygulandı. Özel dizayn edilmiş fikstür ile 8400 Nmm tork oluşturuldu. Fikstür aksiyel yönde fleksiyon, ekstansiyon, sağ ve sola eğilme pozisyonlarında yüklenme uygulanacak şekilde numuneler ayarlandı. Tüm numuneler sağlam omurga, pedikül vida ve rod fiksasyonu sonrasında teste tabi tutuldu. Test esnasında komşu seviye L5-S1 arasındaki ayrılma değerleri süreğen bir şekilde ekstansometre ile kaydedildi. Bulgular: Komşu segmentte (L5-S1), aksiyel yüklenme ve üst-alt ayrılma değerleri, ön-arka ayrılma değerlerinden düşük bulundu. İstatistiksel analizde sağlam omurga ile komşu segment arasında aksiyel kompresyon ve ekstansiyon pozisyonunda sayısal anlamlı değişiklikler tespit edildi (p<0.027). Bunun yanında ekstansiyon pozisyonunda komşu segmentte sağlam omurgaya göre daha yüksek çıktı (p<0.015). Sonuç: Lomber omurganın rijit fiksasyonu komşu segment seviyesinde hareket genişliğini değiştirmektedir. Bundan dolayı, komşu segmentte anormal stres ve spinal instabiliteye neden olur; bu durum, faset eklem dejenerasyonuna ve bel ağrılarına yol açabilir.Anahtar sözcükler: Komşu segment instabilitesi; faset eklem; omurlar arası disk; lomber omurga.Objectives: This study aims to examine the motion and stability of the adjacent segment following rigid fixation of the lumbar spine. Materials and methods:The study included 17 fresh-frozen lamb lumbar spines (including the sacrum to T 12 ). Biomechanical testing was performed using an axial compression testing machine. Axial compression was applied to all the specimens using a loading speed of 5 mm min-1. A specifically designed fixture was used to generate torque ≤8400 Nmm. The fixture was used with each specimen to achieve flexion and extension, axial neutral compression, and right and left bending. All specimens were tested intact, and again after implantation using posterior pedicle screws and rod fixation. During testing intervertebral displacement at the adjacent level (L5-S1) was recorded continuously via extensometry. Results: Axial compression and superior-inferior displacement were lower in the adjacent segment (L5-S1) than anterior-posterior displacement following rigid fixation. Statistical analysis showed that there was a numerical difference and a significant change between the intact spine and the adjacent segment in the axial compression and extension positions (p<0.027). The intact spines demonstrated the maximum displacement and the difference in extension positions were significant (p<0.015). Conclusion: Rigid fixation of the lumbar spine altered the range of motion at the adjacent segment level. As such, abnormal stress on the adjacent segment causes spinal instability, which may subsequently cause facet joint degen...

The skin is the largest and most exposed organ in the human body. Not only it is involved in numerous biological processes essential for life but also it represents a significant endpoint for the application of pharmaceuticals. The area of in vitro skin tissue engineering has been progressing extensively in recent years. Advanced in vitro human skin models strongly impact the discovery of new drugs thanks to the enhanced screening efficiency and reliability. Nowadays, animal models are largely employed at the preclinical stage of new pharmaceutical compounds development for both risk assessment evaluation and pharmacokinetic studies. On the other hand, animal models often insufficiently foresee the human reaction due to the variations in skin immunity and physiology. Skin-on-chips devices offer innovative and state-of-the-art platforms essential to overcome these limitations. In the present review, we focus on the contribution of skin-on-chip platforms in fundamental research and applied medical research. In addition, we also highlighted the technical and practical difficulties that must be overcome to enhance skin-on-chip platforms, e.g. embedding electrical measurements, for improved modeling of human diseases as well as of new drug discovery and development.

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