Initial Stages Of Healing Research Articles

The non-steroidal anti-inflammatory drug diclofenac reduces appearance of osteoblasts in bone defect healing in rats

Non-steroidal anti-inflammatory drug (NSAID) is well known to significantly delay fracture healing. Results from in vitro studies implicate an impairment of osteoblast proliferation due to NSAIDs during the initial stages of healing. We studied whether diclofenac, a non-selective NSAID, also impairs appearance of osteoblasts in vivo during the early phase of healing (at 10 days). Two defects (Ø 1.1 mm) were drilled within distal femurs of 20 male Wistar rats. Ten rats received diclofenac continuously; the other obtained a placebo until sacrificing at 10 days. Osteoblast proliferation was assessed by cell counting using light microscopy, and bone mineral density (BMD) was measured using pQCT. Osteoblast counts from the centre of bone defect were significantly reduced in the diclofenac group (median 73.5 +/- 8.4 cells/grid) compared to animals fed with placebo (median 171.5 +/- 13.9 cells/grid). BMD within the defect showed a significant reduction after diclofenac administration (median 111.5 +/- 9.3 mg/cm(3)) compared to the placebo group (median 177 +/- 45.4 mg/cm(3)). The reduced appearance of osteoblasts in vivo implicates an inhibiting effect of diclofenac on osteoblasts at a very early level of bone healing. The inhibition of proliferation and migration of osteoblasts, or differentiation from progenitor cells, is implicated in the delay of fracture healing after NSAID application.

Propolis: a review of its anti-inflammatory and healing actions

Tissue healing is an adaptive biological response by which the organism repairs damaged tissue. The initial stage of healing is represented by an acute inflammatory reaction, in which inflammatory cells migrate to damaged tissue and phagocyte debris. At a later stage, fibroblasts and endothelial cells proliferate and generate a scar. The occurrence of inflammatory processes and healing imperfections have been a concern for hundreds of years, especially for individuals with healing difficulties, such as diabetics and carriers of peripheral circulation deficiencies. A wide variety of natural products have been used as anti-inflammatory and healing agents, with propolis being a remarkable option. Propolis has been used in popular medicine for a very long time; however, it is not a drug intended for all diseases. Currently, the determination of quality standards of propolis-containing products is a major problem due to their varying pharmacological activities and chemical compositions. The aim of this review is to discuss the use of propolis with emphasis on its anti-inflammatory and healing properties.

Instability prolongs the chondral phase during bone healing in sheep

In this sheep study, we investigated the influence of fixation stability on the temporal and spatial distribution of tissues in the fracture callus. As the initial mechanical conditions have been cited as being especially important for the healing outcome, it was hypothesized that differences in the path of healing would be seen as early as the initial phase of healing. Sixty-four sheep underwent a mid-shaft tibial osteotomy that was treated with either a rigid or a semi-rigid external fixator. Animals were sacrificed at 2, 3, 6 and 9 weeks postoperatively and the fracture calluses were analyzed using radiological, biomechanical and histological techniques. Statistical comparison between the groups was performed using the Mann–Whitney U test for unpaired non-parametric data. In the callus of the tibia treated with semi-rigid fixation, remnants of the fracture haematoma remained present for longer, although new periosteal bone formation during early healing was similar in both groups. The mechanical competence of the healing callus at 6 weeks was inferior compared to tibiae treated with rigid fixation. Semi-rigid fixation resulted in a larger cartilage component of the callus, which persisted longer. Remodeling processes were initiated earlier in the rigid group, while new bone formation continued throughout the entire investigated period in the semi-rigid group. In this study, evidence is provided that less rigid fixation increased the time required for healing. The process of intramembranous ossification appeared during the initial stages of healing to be independent of mechanical stability. However, the delay in healing was related to a prolonged chondral phase.

Exogenously Administered Substance P and Neutral Endopeptidase Inhibitors Stimulate Fibroblast Proliferation, Angiogenesis and Collagen Organization during Achilles Tendon Healing

In the last few years much research has been conducted in methods to promote tendon healing. The aim of this study was to determine if the healing process after operative repair of rat Achilles tendons could be stimulated by the paratendinous injection of a sensory peptide, substance P (SP). Ninety-six male Sprague-Dawley rats were randomly allocated to four groups: (I) control buffer injections, (II) injections of SP 10(-6) mol/kg body weight combined with a carrier, (III) injections of SP 10(-8) mol/kg BW with the carrier, and (IV) injections with the carrier only (thiorphan 1 micromol/kg BW and captopril 30 micromol/kg BW, both neutral endopeptidase inhibitors). The influence on tissue repair was determined from the histologic measurement of fibroblast proliferation, angiogenesis, and collagen organization. On days 7, 14, 28 and 42, animals were sacrificed and histologic evaluations were performed on the injured Achilles tendon constructs. The two groups subjected to SP injections showed a significant initial fibroblast proliferation on day 7 (p < 0.05), which rapidly declined by day 14 to the level of cellular proliferation observed with the use of thiorphan and captopril. Capillary proliferation showed a similar evolution, except that in the second week angiogenesis in the treated groups was below the level of the control group. Strikingly, collagen orientation increased faster in the groups injected with SP. This was obvious from the second week already and the difference remained until the completion of the study. This is the first study to demonstrate that paratendinous injections of SP after operative repair of the Achilles tendon in rats appears to provide a boost to the initial stages of healing and significantly accelerate the reparative phase of the healing process.

Effect of Adrenalectomy on Healing of Indomethacin-Induced Gastric Erosions in Rats

We studied the effects of adrenalectomy and replacement therapy on healing of gastric erosions in adult Sprague-Dawley rats developed 4 h after subcutaneous injection of indomethacin in a dose of 25 or 35 mg/kg. Adrenalectomy was performed 1 week before or 4 h after indomethacin administration. Healing was evaluated by changes in the area of erosions over 24 h after indomethacin administration at fixed time intervals. Plasma corticosterone was measured. Adrenalectomy (irrespective of the time of intervention) decelerated healing of gastric injuries. Injection of corticosterone in a physiological dose of 4 mg/kg at the initial stage of healing (4 h after indomethacin administration) improved healing of erosions.

Early controlled mobilization of potentially unstable extra-articular hand fractures

This article presents early controlled mobilization options for potentially unstable, nondisplaced, nonarticular hand fractures. Early controlled mobilization of tissues surrounding a healing fracture has the potential to enhance the quality and rate of fracture healing and a person's functional recovery. The options discussed protect the integrity of the fracture alignment, while permitting safe, pain-free protected motion of joints adjacent to the fracture. Traditionally, healing fractures are thought of as clinically stable or unstable. If clinically unstable, the fracture often is considered unable to tolerate unrestricted active motion during the initial stages of healing. This article offers an alternative perspective, in which clinicians can consider the clinical factors that can be controlled to allow for early protected motion of the regional tissues surrounding a potentially unstable hand fracture. These additional clinical options offer an alternative to acute fracture immobilization and help progress the rehabilitation of hand fracture patients. J HAND THER. 2003;16:161-170.

Healing internalized racism: the role of a within-group sanctuary among people of African descent.

This article addresses the role of a "within-group" sanctuary for healing internalized racism among people of African descent. Internalized racism is distinguished from racism, juxtaposing the different experience of those who are oppressed and those who are privileged by racism. It is suggested that a context consisting exclusively of persons of African descent can provide an optimally safe space for initial stages of healing from internalized racism. The anxiety that a collective of African descendants can generate among whites, and subsequently among those of African descent, is examined by raising questions as to its possible meanings. Whites are encouraged to use their privilege to support such self-determined sanctuaries, rather than to obstruct them. People of African descent are encouraged to tolerate the anxiety that can be generated without "changing back," and to examine whether internalized racism is also implicated.

Adhesion of microvascular endothelial cells to metallic implant surfaces.

The objective of this study was to explore the molecular mechanisms of adhesion of endothelial cells (ECs) to implant grades of titanium alloy (Ti) and stainless steel (SS), compared to tissue culture polystyrene (PS). The idea is that promotion of EC adhesion to implant surfaces during the initial stages of healing may be critical in the formation of a capillary bed intimately associated with the implant surface. Ultimately this could be expected in turn to promote bone formation close to the surface and a more stable implant/bone interface. Surfaces were coated with either peak 1 fibrinogen gammaAgammaA, fibrinogen Fr I-9, fibrinogen fragment D1, fibronectin, vitronectin, or fetal calf serum and then post-coated with bovine serum albumin (BSA) to block non-specific cell adhesion. Surfaces with BSA alone and no other protein coating were also evaluated. Fibronectin coating maximized cell adhesion on all three surfaces, and adhesion was highest on PS. BSA blocked cell adhesion to PS (and most adhesion to SS) much better than to Ti. These results provide evidence that BSA adsorption on the metal surface is unable to effectively block the adhesion of the cells to the Ti. These data may provide a basis for understanding in vivo observations that soft tissue becomes attached to a Ti surface more rapidly and with more bone formation than to SS. Evidence is also presented that alphavbeta3 plays an important role in adhesion of ECs to the Ti surface. These experiments also provide preliminary data which may reflect some of the features of initial EC adhesion to metal implants.

Asiaticoside-induced elevation of antioxidant levels in healing wounds.

Asiaticoside derived from the plant Centella asiatica is known to possess good wound healing activity. Enhanced healing activity has been attributed to increased collagen formation and angiogenesis. Since antioxidants have been reported to play a significant role in the wound healing process we studied the effect of asiaticoside on the levels of certain antioxidants in the wound so as to explore the possible involvement of such a mechanism in the asiaticoside induced wound healing. Asiaticoside application (0.2%, topical) twice daily for 7 days to excision-type cutaneous wounds in rats led to increased enzymatic and non-enzymatic antioxidants, namely superoxide dismutase (35%), catalase (67%), glutathione peroxidase (49%), vitamin E (77%) and ascorbic acid (36%) in newly formed tissues. It also resulted in a several fold decrease in lipid peroxide levels (69%) as measured in terms of thiobarbituric acid reactive substance. However, continued application for 14 days showed no significant difference in these antioxidants compared with their values in vehicle treated wound tissue. It appears from the present study that asiaticosides enhanced induction of antioxidant levels at an initial stage of healing which may be an important contributory factor in the healing properties of this substance.

Induction of mitogen-activated protein kinase signal transduction pathway during gastric ulcer healing in rats

Background & Aims: Previous studies have shown that gastric ulceration stimulates epithelial cell proliferation and overexpression of epidermal growth factor (EGF) and EGF receptor (EGF-R) in the mucosa bordering necrosis. The aim of this study was to investigate whether extracellular signal-regulated kinase (ERK) cascade is involved in the healing of experimental gastric ulcers. Methods: We studied EGF-R levels, EGF-R phosphorylation levels, and ERK1 and ERK2 activity in normal and ulcerated rat gastric mucosa. We also examined the effect of Tyrphostin A46 (potent inhibitor of EGF-R and EGF-R kinase–dependent proliferation) on the above parameters. Results: During the initial stages of healing (3 and 7 days), ulcerated mucosa showed significant increase (vs. controls) in protein tyrosine kinase activity, EGF-R levels (510% and 550%), EGF-R phosphorylation levels, ERK1 activity (430% and 880%), and ERK2 activity (550% and 990%). Tyrphostin A46 treatment significantly inhibited ulcer healing and reduced EGF-R levels, EGF-R phosphorylation, and ERK1 and ERK2 activity. Conclusions: These findings indicate that experimental gastric ulcer healing involves activation of EGF-R–ERK signal transduction pathway. GASTROENTEROLOGY 1998;114:706-713

Changes in the levels and distribution of glycogen during regeneration of cutaneous wounds in Heteropneustes fossilis: a histochemical investigation

Incisional wounds of the same length and depth were made in the skin of catfish Heteropneustes fossilis, and the response in terms of levels of glycogen in cells during healing was studied histochemically. After injury, glycogen disappeared completely from the cells in the migrating epidermis. This disappearance is correlated with the migration of the epidermal cells toward the wound gap for epithelialization and the increased production of mucous cells at the initial stages of healing. The gradual accumulation of glycogen in the epithelial cells and the basal cells after epithelialization of the wound during the early stages of healing suggests that in these cells gluconeogenesis predominates. The gradual disappearance of glycogen from the epithelial cells 72 h after injury and from the basal cells 36 h after injury indicates the gradual resumption of their metabolic activities. The increased gradients of glycogen in club cells that are undergoing vacuolization and disintegration are discussed. No significant levels of glycogen were observed during the formation of granulation tissue and biosynthesis of the sub‐cutis. The depletion of glycogen in the degenerating muscle bundles is correlated with the synthesis of lactic acid which contributes to local acidity and favours the autolysis of muscles.

Role of interfragmentary strain in fracture healing: Ovine model of a healing osteotomy

It has been hypothesized that the histological pattern of fracture healing is controlled at least in part by the local mechanical strains in the interfragmentary region. To test this "interfragmentary strain hypothesis," we applied cyclic bending deformations to tibial osteotomies in 11 sheep. An instrumented flexible plate spanning a 1-mm osteotomy gap was deformed to create a gradient of tissue elongation from 10% under the plate to 100% at the opposite cortex. The cyclic deformations were applied three times per minute, 24 h per day, for 1-5 weeks. However, as a result of tissue differentiation, the bone-plate complex increased in stiffness with healing time, resulting in a marked reduction of the gap deformation at approximately 4 weeks. Fracture healing was evaluated using vascular injection of India ink and conventional histology. A nonlinear three-dimensional finite element model of the interfragmentary tissue at the initial stage of healing was used to predict the complex tissue strains. The ingrowth of vascularized soft tissue into the interfragmentary gap, as well as the subsequent differentiation of this tissue, occurred earlier and to a greater degree in regions of lower strain. In contrast, the proliferation of callus tissue was greatest at the periosteal and endosteal surfaces of the cortex opposite the plate. Direct comparison of the finite element predictions with the histology demonstrated that the spatial distribution of bone resorption at the fracture fragment ends directly corresponded to the locations of elevated tissue strain and stress. However, there was no consistent numerical relationship between the magnitude of these local peak strains and the corresponding volume of cortical bone resorption over the bone cross section.

Observations on the initial stages of healing following human experimental gingivitis. A clinical and morphometric study.

The aim of the present study was to investigate stereologically the histologic alterations occurring during gingival healing after experimental gingivitis and to compare clinical parameters with histological findings. 8 dental students volunteered for the investigation. After a prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching zero. They then abolished all oral hygiene procedures for a period of 21 days. After this experimental gingivitis phase, they again performed optimal oral hygiene for 8 days to restore gingival health. At days 0, 1, 2, 4 and 8 after experimental gingivitis, the plaque index (PlI), the gingival index (GI) and the gingival exudate flow rate (GEFR) were assessed and their buccal gingiva was biopsied. Point counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells and macrophages were estimated by counting the number of profiles of these cells in a specific connective tissue area adjacent to the apical end of the junctional epithelium. A rapid drop in the PlI was noted with increasing time after oral hygiene, followed by a slower decrease in the GI and GEFR scores. The histological picture during the entire experiment was that of an initial gingival lesion. At day 0, no chronic inflammation of the gingiva characterized by a predominance of plasma cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Collagen membranes prevent the apical migration of epithelium during periodontal wound healing.

Collagen membranes were interposed between full thickness periodontal flaps and denuded root surfaces of right upper canines in 3 mongrel dogs; the left canines were sham‐operated without the use of collagen membranes. Animals were killed 10 d after surgery. Tissue blocks were removed, and experimental and control sites were processed for histometric and histologic examination. The results indicate that collagen membranes: (i) prevent apical migration of the epithelium during initial stages of healing; and (ii) are colonized by connective tissue cells and incorporated within the healing connective tissue.

Comparison of cyclic loading versus constant compression in the treatment of long-bone fractures in rabbits.

The strengths of healing long-bone fractures treated in two different mechanical environments were compared using a rabbit experimental model. Constant compression was applied to one healing tibial fracture, while the other was subjected to cyclic compression. At six weeks of healing, the group of tibial fractures treated with cyclic loading exhibited significantly higher torque and energy absorption to failure and lower stiffness than their pair-mates treated with constant compression. No statistically significant differences were detected at four or eight weeks of healing, although there was a suggestion that compression-treated bones may be stronger in the earlier phases of healing. This experiment suggests that the requirements for rapid fracture-healing may vary with the stage of healing; that is, rigid immobilization applied during the initial stages of healing followed by intermittent compression during later stages.

Glycogen in Rachitic Cartilage and Its Relation to Healing.

SummaryGlycogen is present in rachitic cartilage only in the most recently matured hypertrophic cells. The broad zone of hypertrophic cells beneath is devoid of glycogen. This localization coincides with the area where inorganic elements deposit during the initial stages of healing and furnishes further evidence for the relationship of glycogen, and possibly the glycogenolytic cycle, to the calcification mechanism.