Biomechanical assessment and clinical analysis of different intramedullary nailing systems for oblique fractures

The aim of this study is to evaluate the fracture union or non-union for a specific patient that presented oblique fractures in tibia and fibula, using a mechanistic-based bone healing model. Normally, this kind of fractures can be treated through an intramedullary nail using two possible configurations that depends on the mechanical stabilisation: static and dynamic. Both cases are simulated under different fracture geometries in order to understand the effect of the mechanical stabilisation on the fracture healing outcome. The results of both simulations are in good agreement with previous clinical experience. From the results, it is demonstrated that the dynamization of the fracture improves healing in comparison with a static or rigid fixation of the fracture. This work shows the versatility and potential of a mechanistic-based bone healing model to predict the final outcome (union, non-union, delayed union) of realistic 3D fractures where even more than one bone is involved.     

Observation of an improved healing process in superficial skin wounds after irradiation with a blue‐LED haemostatic device

The healing process of superficial skin wounds treated with a blue‐LED haemostatic device is studied. Four mechanical abrasions are produced on the back of 10 Sprague Dawley rats: two are treated with the blue‐LED device, while the other two are left to naturally recover. Visual observations, non‐linear microscopic imaging, as well as histology and immunofluorescence analyses are performed 8 days after the treatment, demonstrating no adverse reactions neither thermal damages in both abraded areas and surrounding tissue. A faster healing process and a better‐recovered skin morphology are observed: the treated wounds show a reduced inflammatory response and a higher collagen content.

Blue LED induced photothermal effect on superficial abrasions.     

Microtubule cytoskeleton in intact and wounded coenocytic green algae

Microtubule (MT) arrangements were investigated, with immunofluorescence and electron microscopy, in two related species of coenocytic green algae. Intact cells of both Ernodesmis verticillata (Kützing) Boergesen and Boergesenia forbesii (Harvey) Feldmann have two morphologically distinct populations of MTs: a highly regular cortical array consisting of a single layer of parallel, longitudinal MTs; and perinuclear MTs radiating from the surface of the envelope of each interphase nucleus. In both algae, mitotic figures lack perinuclear MTs around them. Pre-incubation with taxol does not alter the appearance of these arrays. The cortical and nuclear MTs appear to coexist throughout the nuclear cycle, unlike the condition in most plant cells. At the cut/contracting ends of wounded Ernodesmis cells, cortical MTs exhibit bundling and marked convolution, with some curvature and slight bundling of MTs throughout the cell cortices. In Boergesenia, wound-induced reticulation and separation of the protoplasm into numerous spheres also involves a fasciation of MTs within the attenuating regions of the cytoplasm. Although some cortical MTs are fairly resistant to cold and amiprophos-methyl-induced depolymerization, the perinuclear ones are very labile, depolymerizing in 5–10 min in the cold. The MT cytoskeleton is not believed to be directly involved in wound-induced motility in these plants because amiprophos-methyl and cold depolymerize most cortical MTs without inhibiting motility. Also, the identical MT distributions in intact cells of these two algae belie the very different patterns of cytoplasmic motility. Although certain roles of the MT arrays may be ruled out, their exact functions in these plants are not known.Abbreviations APM amiprophos-methyl - DIC differential interference contrast - EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - FITC fluorescein isothiocyanate - MT(s) microtubule(s) - PBS phosphate-buffered saline     

Wound currents and wound healing in the newt,Notophthalmus viridescens

Summary Wounded amphibian skin heals initially by a migration of epithelial cells from the cut edge towards the center of the wound. The density of currents leaving wounds made in Notophthalmus viridescens skin was manipulated in order to determine whether electrical fields associated with these currents might have a significant role in promoting this cell migration during wound healing. Wounds were made with either a needle (200 m) or a biopsy punch (500 m). Currents leaving the wounds were measured with a vibrating probe, and the wounds fixed at various times after wounding. When the Na⁺-dependent currents were reduced by blocking Na⁺ channels with benzamil, wound healing, as revealed by scanning electron microscopy and by paraffin histology, was impaired. These results are consistent with the hypothesis that there is an electrical component to wound healing.     

Initiation of proliferative events by human alpha-thrombin requires both receptor binding and enzymic activity

To determine the role of thrombin high-affinity receptor occupancy and enzymic activity in thrombin initiation of cell proliferation, we have utilized thrombin derivatives which separate these functions. We previously showed that enzymically active gamma-thrombin stimulates ion fluxes without binding to high-affinity sites, whereas proteolytically inhibited DIP-alpha-thrombin which binds to high-affinity receptors does not. Since neither derivative initiates DNA synthesis by itself, this suggested that two separate sequences of events might be necessary for a complete initiation signal. We now report that the combination of DIP-alpha-thrombin and gamma-thrombin initiate DNA synthesis and cell proliferation to levels approaching the maximal initiation by native alpha-thrombin. This combinatory effect is dose-dependent for both gamma-thrombin and DIP-alpha-thrombin in the same concentration range as alpha-thrombin alone. Thus, these same concentrations of alpha-thrombin alone may be required to initiate each sequence of events. The combinatory stimulation could be achieved even if the derivatives were added individually up to 8 hr apart. Moreover, preincubation with either derivative shortened the lag period for initiation of DNA synthesis by native alpha-thrombin. These results indicate that both receptor occupancy and enzymic activity are necessary for thrombin initiation of cell proliferation and that each action initiates a sequence of early events which moves the cell forward toward entry into a proliferative cycle.     

Deregulated unfolded protein response in chronic wounds of diabetic ob/ob mice: A potential connection to inflammatory and angiogenic disorders in diabetes-impaired wound healing

Type-2 diabetes mellitus (T2D) represents an important metabolic disorder, firmly connected to obesity and low level of chronic inflammation caused by deregulation of fat metabolism. The convergence of chronic inflammatory signals and nutrient overloading at the endoplasmic reticulum (ER) leads to activation of ER-specific stress responses, the unfolded protein response (UPR). As obesity and T2D are often associated with impaired wound healing, we investigated the role of UPR in the pathologic of diabetic-impaired cutaneuos wound healing. We determined the expression patterns of the three UPR branches during normal and diabetes-impaired skin repair. In healthy and diabetic mice, injury led to a strong induction of BiP (BiP/Grp78), C/EBP homologous protein (CHOP) and splicing of X-box-binding protein (XBP)1. Diabetic-impaired wounds showed gross and sustained induction of UPR associated with increased expression of the pro-inflammatory chemokine macrophage inflammatory protein (MIP)2 as compared to normal healing wounds. In vitro, treatment of RAW264.7 macrophages with tunicamycin, and subsequently stimulation with lipopolysaccharide (LPS) and interferon (IFN)-γ enhances MIP2 mRNA und protein expression compared to proinflammatory stimulation alone. However, LPS/IFNγ induced vascular endothelial growth factor (VEGF) production was blunted by tunicamycin induced-ER stress.     

The Effects of Sericin Cream on Wound Healing in Rats

Sericin has good hydrophilic properties, compatibility, and biodegradation, it can be used as a wound-healing agent. We evaluated the effects of sericin on wound healing and wound size reduction using rats by generating two full-thickness skin wounds on the dorsum. Group 1 animals were treated with Betadine^® on left-side (control) wounds and, with 8% sericin cream on right-side (treated) wounds. Group 2, cream base (formula control) and 8% sericin cream (treated) were topically applied to left-, and right-side wounds respectively. Sericin-treated wounds had much smaller inflammatory reactions, and wound-size reduction was much greater than in the control throughout the inspection period. Mean time in days for 90% healing from sericin-treated wounds was also much less than for cream base-treated wounds. Histological examination after 15 d of treatment with 8% sericin cream revealed complete healing, no ulceration, and an increase in collagen as compared to cream base-treated wounds, which showed some ulceration and acute inflammatory exudative materials.     

The Patchwork Mouse Phenotype: Implication for Melanocyte Replacement in the Hair Follicle

Mice homozygous for the recessive patchwork (pwk) mutation are characterized by a variegated pigment pattern with a mixture of unpigmented and normally pigmented hairs. The pigmented hair bulbs contain functional melanocytes. By contrast, the unpigmented hair bulbs contain no melanocytes. This lack results from the death of melanoblasts in the hair follicle at the end of embryogenesis. Here, we report that melanoblasts and melanocytes are found in the epidermis of pwk/pwk mice. Furthermore, these epidermal pigment cells are able to colonize new hair follicles after skin wounding. Despite the presence of epidermal pigment cells with a colonization potential, a follicle that had produced an unpigmented hair produces a new unpigmented hair during the successive hair growth cycles. This hair color continuity is also true for the pigmented hair follicles. Thus, in normal conditions, the hair acts as an independent functional unit as regards its pigment cells population.