A compact differential laser Doppler velocimeter using a semiconductor laser

A small differential laser Doppler velocimeter which uses a semiconductor laser and a small number of optical components is described. In this device the light from the laser diode is split into coherent beams by means of a diffraction grating. The two first-order beams are crossed in a probe volume with a lens. In a test experiment the velocity of water containing 0.9 mu m polystyrene spheres was determined from the fluctuation of the scattered light. This velocity agreed with the velocity calculated from flux measurements

Characterization of fibroblast phenotypes in intra-oral wound healing.

Contains fulltext : 51360.pdf (publisher's version ) (Open Access)Wound contraction and subsequent scar tissue formation is thought to be a main cause of the maxillary and dento-alveolar growth inhibition observed after cleft palate surgery. A reduction in wound contraction and scar tissue formation might prevent these iatrogenic effects. To achieve this, different approaches have been chosen in the past. Nowadays, a main approach is to interfere with fibroblast activity, since these cells play a key role during wound contraction and scar tissue formation. First, wound fibroblasts have to be characterized. Therefore, tissue samples were taken from different phases of the wound healing process in rats. The tissues were used to analyze the expression of different integrins and cytoskeletal markers in vivo and in vitro. Furthermore, the functional activity of fibroblast phenotypes was determined by comparing adhesion and migration of fibroblasts from early and late phases of wound healing with age-matched cells from unwounded palates. From the studies we can conclude that heterogeneous populations of fibroblasts are present in the course of palatal wound healing. These different subpopulations can be isolated and cultured, and maintain their characteristics up to seven passages. We distinguished two main fibroblast phenotypes both during palatal wound healing in vivo, and in vitro: an early activated phenotype and a late more quiescent phenotype. These fibroblast phenotypes were also observed in the functional assays for adhesion and migration. The modulation of activity of these specific fibroblast phenotypes might offer a good starting point for the control of wound contraction and scar formation. Ultimately, this will lead to an improved wound healing process after cleft palate repairRU Radboud Universiteit Nijmegen, 16 januari 2006Promotor : Kuijpers-Jagtman, A.M. Co-promotores : Hoff, J.W. Von den, Torensma, R.173 p

ACCIRT/WRC Newsletter [30 April, 2008]

Item does not contain fulltextWhen cells are injured they release their contents, resulting in a local accumulation of free heme proteins and heme. Here, we investigated the involvement of heme and its degrading enzyme heme oxygenase (HO) in the inflammatory process during wound healing. We observed that heme directly accumulates at the edges of the wound after inflicting a wound in the palate of Wistar rats. This coincided with an increased adhesion molecule expression and the recruitment of leukocytes. To prove that heme is responsible for the recruitment of leukocytes, heme was administered intradermally 24 hours prior to injury. A clear heme-induced influx of both macrophages and granulocytes was observed. When examining the HO isoforms, HO-1 and HO-2, we found that HO-2 was present in the entire submucosa. Surprisingly, we observed also that HO-1 is significantly expressed in the epithelium of both the mucosa and the skin of animals without wounds. On inflammation, HO-1 expression increased, particularly in infiltrating cells during the resolution phase of inflammation. Interestingly, we observed that heme-induced influx of leukocytes was highly elevated after pharmacologic inhibition of HO activity. These observations suggest that the heme-HO system is closely involved in the control of wound healing. Our results demonstrate that the local release of heme may be a physiologic trigger to start inflammatory processes, whereas HO-1 antagonizes inflammation by attenuating adhesive interactions and cellular infiltration. Moreover, the basal level of HO expression in the skin may serve as a first protective environment against acute oxidative and inflammatory insults

Myofibroblasts in palatal wound healing: prospects for the reduction of wound contraction after cleft palate repair.

Contains fulltext : 48896.pdf (publisher's version ) (Closed access)The surgical closure of orofacial clefts is considered to impair maxillary growth and dento-alveolar development. Wound contraction and subsequent scar tissue formation, during healing of these surgical wounds, contribute largely to these growth disturbances. The potential to minimize wound contraction and subsequent scarring by clinical interventions depends on the surgeon's knowledge of the events responsible for these phenomena. Fibroblasts initiate wound contraction, but proto-myofibroblasts and mature myofibroblasts are by far the most important cells in this process. Myofibroblasts are characterized by their cytoskeleton, which contains alpha-smooth-muscle actin. Additionally, their contractile apparatus contains bundles of actin microfilaments and associated contractile proteins, such as non-muscle myosin. This contractile apparatus is thought to be the major force-generating element involved in wound contraction. After closure of the wound, the myofibroblasts disappear by apoptosis, and a less cellular scar is formed. A reduction of contraction and scarring might be obtained by inhibition of myofibroblast differentiation, stimulation of their de-differentiation, stimulation of myofibroblast apoptosis, or impairment of myofibroblast function. In this review, we will discuss all of these possibilities, which ultimately may lead to a better outcome of cleft palate surgery

Fibroblast subpopulations in intra-oral wound healing.

Item does not contain fulltextThe objective of this study was to characterize fibroblasts at sequential time points during intra-oral wound healing in the rat. Experimental wounds were made at several time points in the mucoperiosteum of the palate of 35-day-old Wistar rats. Fibroblasts were cultured from the biopsies under standard conditions for the same number of passages. The expression of the integrin subunits alpha 1, alpha 6, and beta 1; and the intermediate filaments alpha-smooth muscle actin and vimentin were analyzed by flow cytometry. Western blot analysis was performed at 0, 8, and 60 days postwounding to confirm the expression of both intermediate filaments. The phenotypic profiles of fibroblasts cultured from subsequent stages in the wound healing process differed considerably. We conclude that distinct fibroblast phenotypes can be isolated from different stages in wound healing. These phenotypes remained stable during in vitro culturing. In addition, cryosections of the wound areas were made at identical time points and were immunohistochemically stained for the same antigens. The immunohistochemical staining correlated well to the flow-cytometric data. These results suggest the occurrence of multiple subpopulations of fibroblasts with a specialized function during wound healing. We hypothesize that undesirable consequences of wound healing might be prevented through the modulation of specific fibroblast subpopulations