Burn healing in organ cultures of embryonic chicken skin: a model system

Burn wounds cause complex damage to the skin. Unlike simple cuts, burns cause a graded damage at the margin of the wound and leave biochemically complex debris in the wound, two factors that complicate the process of wound healing. To develop an in vitro system for studying cellular responses to burns in whole tissue, we have applied a standardized burn wound to organ cultures of embryonic chicken skin and evaluated cellular changes in response to the burn damage. This simplified system is not subject to uncontrolled infection and does not involve angiogenesis and granulation. Thus, these cultures provide a simplified model of how cells of the dermis and epidermis in and around a burn wound respond to heat damage early in the process of healing.     

Centralized echocardiogram quality control in a multicenter study of regression of left ventricular hypertrophy in hypertension

Deep skin wounds in the adult mammal close spontaneously by epithelialization, wound contraction, and scar synthesis. In previous wound healing studies, it has been unsuccessfully attempted to separate from each other the natural processes that close wounds. In this study, we attempted to isolate skin regeneration from spontaneous processes of wound closure using "island" grafts. A porous analog of the extracellular matrix, composed of a graft copolymer of type I collagen and chondroitin 6-sulfate, was seeded with uncultured autologous keratinocytes and served to induce regeneration of the dermis and the epidermis. Grafts of the copolymer, measuring 1 x 2 cm, were placed in the center of 5 x 6-cm wounds in guinea pigs. By day 14, the edges of the island grafts were clearly separated from the host epidermis and dermis by a distinct bed of granulation tissue. Histologic study of island grafts on day 14 showed that the copolymer grafts had largely degraded and that a new epidermis and dermis had been synthesized in its place. The thickness of the new epidermis increased as the density of cells seeded into the graft increased. No synthesis of epidermis or dermis was observed in the granulation tissue outside the perimeter of the island grafts. We conclude that island grafting allows the study of early events in skin regeneration in isolation from epithelialization, contraction, and scar synthesis.     

Promotion of second intention wound healing by emu oil lotion: comparative results with furasin, polysporin, and cortisone

Previous studies showed that twice-daily application of emu oil lotion (mixture of emu oil/fat, vitamin E, and botanical oil) immediately after creation of full-thickness skin defects delayed wound healing 6 days later, perhaps owing to its antiinflammatory actions. If administration was delayed for 48 hours, a two-fold promotion of wound contraction, epithelialization, and infiltration of organized granulation tissue was observed. In the present study, emu oil lotion was applied to full-thickness skin defects in rodents 24 hours after surgery. Six days postoperatively, wound contraction and infiltration of fronts of epithelialized and granulation tissue were assessed. Results indicated a two-fold promotion of all of the above parameters with emu oil lotion. No such effects were exerted by pure emu oil, furasin, cortaid, or polysporin. Data obtained indicate promise for emu oil lotion as an aid in treating full-thickness skin defects if applied after the major postinflammatory stages of wound healing have transpired.     

Analysis of the tissue movements of embryonic wound healing--DiI studies in the limb bud stage mouse embryo

The tissue movements of epithelial spreading and mesenchymal contraction play key roles in many aspects of embryonic morphogenesis. One way of studying these movements in a controlled manner is to make an excisional skin wound to an embryo and watch the wound heal. In this paper we report our studies of healing of a simple excisional lesion made to the limb bud stage mouse embryo. The wounded, living embryo is cultured in a roller bottle; under such conditions the wound heals with a highly reproducible time course and is completely closed by 24 hr. During the healing period the environment bathing the wound can be simply manipulated by adding drugs or factors to the culture medium. We have used DiI to label mesenchymal cells exposed at the margin of the initial wound and, by following their fate and measuring the area of mesenchyme remaining exposed at various time points during the healing process, we have quantified both the extent of mesenchymal contraction and the extent of reepithelialisation by movement of epidermis over mesenchyme. We show that the two types of tissue movement contribute almost equally (50:50) to the total wound closure rate. We have gone on to investigate the cell machinery underlying these processes. In adult wounds the epidermis migrates by means of lamellipodial crawling, but we show that reepithelialisation in the embryo is achieved instead by purse-string contraction of a cable of filamentous actin which assembles in the basal layer of cells at the free edge of the epidermis. Addition of cytochalasin D to the culture medium blocks formation of this actin cable and leads to failure of reepithelialisation. Contraction of adult wound connective tissue appears to be driven by conversion of dermal fibroblasts into a specialist smooth muscle-like fibroblast, the myofibroblast. However, using an antibody recognising the alpha-isoform of smooth muscle actin and specific for smooth muscle cells and myofibroblasts, we show that a similar conversion into myofibroblasts does not occur at any stage during the embryonic wound healing process. These observations indicate that both of the tissue movements of embryonic wound healing utilise cell machinery fundamentally different from that driving the analogous tissue movements of adult healing.     

Electron microscopic observations on sperm penetration in cytochalasin-treated eggs of the rose bitterling

The influence of Aloe vera (L.) Burman f. on the glycosaminoglycan (GAG) components of the matrix in a healing wound was studied. Wound healing is a dynamic and complex sequence of events of which the major one is the synthesis of extracellular matrix components. The early stage of wound healing is characterized by the laying down of a provisional matrix, which is then followed by the formation of granulation tissue and synthesis of collagen and elastin. The provisional matrix or the ground substance consists of GAGs and proteoglycans (PGs), which are protein GAG conjugates. In the present work, we have studied the influence of Aloe vera on the content of GAG and its types in the granulation tissue of healing wounds. We have also reported the levels of a few enzymes involved in matrix metabolism. The amount of ground substance synthesized was found to be higher in the treated wounds, and in particular, hyaluronic acid and dermatan sulphate levels were increased. The levels of the reported glycohydrolases were elevated on treatment with Aloe vera, indicating increased turnover of the matrix. Both topical and oral treatments with Aloe vera were found to have a positive influence on the synthesis of GAGs and thereby beneficially modulate wound healing.     

Simultaneous optimization of wet granulation process involving factor of drug content dependency on granule size

Computer optimization technique was applied to the simultaneous optimization of wet granulation process by a high-speed mixer granulator. Four pharmaceutical properties, including yield, drug content uniformity, geometrical mean diameter of granules, and uniformity of granule size, were selected to evaluate the quality of the granules. In particular, dependence of drug content uniformity on granule size was investigated using two model drugs, ascorbic acid and ethenzamide. An appreciable dependence of ascorbic acid content on granule size was not observed in model formulations. On the other hand, ethenzamide was contained more in small-size granules, and its content was decreased with an increase in amounts of hydroxypropyl cellulose (HPC-L; used as a binder) and binder solution. These observations suggested that drug content uniformity is influenced not only by drug solubility in the binder solution, but also by the use of HPC-L. A simultaneous optimal point incorporating four pharmaceutical properties was obtained using the generalized distance function. The experimental values of the four response variables obtained in newly prepared granules were found to correspond well with the predicted values of both granules containing ascorbic acid and ethenzamide. These results suggested that computer optimization would benefit the wet granulation process even if drug content segregation was involved in the process. Further, data obtained from computer optimization, in particular the contour diagram, will be valuable in the process validation.     

Basics of cutaneous wound repair

BACKGROUND: Cutaneous wound repair consists of multiple integrated networks of cell-matrix-cytokine interactions. It is generally believed that a better understanding of these networks will lead to improved care of cutaneous wounds, whether freshly made by the surgeon's scalpel or previously existing and not healing secondary to underlying abnormalities. OBJECTIVE: This review is intended to update the readership in some of the salient aspects of wound repair networks. METHODS: To facilitate the review of multiple integrated networks, cutaneous wound repair was arbitrarily divided into three phases: inflammation, tissue regeneration including re-epithelialization and granulation tissue formation, and tissue reorganization. RESULTS: Throughout the entire process of wound repair it is clear that cells produce or alter various cytokines and extracellular matrix. The cytokines and matrix in turn alter the behavior of the producer cells (autocrine response) or neighbor cells (paracrine response). CONCLUSION: The dynamic reciprocity among cells, cytokines, and matrix material helps explain how integrated wound healing networks are sequential as well as tightly controlled.     

Biafine applied on human epidermal wounds is chemotactic for macrophages and increases the IL-1/IL-6 ratio

Using a model of pure epidermal wounds in normal human volunteers, we have studied the effects of Biafine emulsion firstly on inflammatory cell migration, vascular permeability and cytokine release during the first 24 h, and secondly on epidermal wound healing by measuring transepidermal water loss from day 1 to day 7. Under these conditions, Biafine does not improve epidermal healing, in contrast to what is observed with bleeding dermoepidermal wounds. Our results suggest that the effects of Biafine are essentially at the dermis level. The analysis of epidermal wound exudates leads to the same conclusion. As a matter of fact, we demonstrated that Biafine is chemotactic for macrophages and increases the IL-1/IL-6 ratio, chiefly by reducing the secretion of IL-6. This study permits to progressively clarify the mode of action of Biafine, that seems to be located at the level of granulation tissue formation and not at the epidermal level.     

Periradicular curettage

Periradicular curettage is a part of the treatment procedure of periradicular surgery. Its main purpose is to remove pathological periradicular tissues for visibility and accessibility to facilitate the treatment of the apical root canal system, or sometimes for the removal of harmful foreign materials present in the periradicular area. Inflammatory periradicular lesions (granuloma and cysts) are the responses of the periradicular tissues to irritants from the root canal and not from the periradicular area unless medicaments and/or filling materials have been forced through the apical foramina or perforations into the periodontium. Histologically, the inflammatory periradicular lesion is similar to healing granulation tissue, which is composed of cells which have natural and specific immunological defence capability and cooperate by means of cytokines to amplify the protective mechanisms of the host. Accordingly, it is not necessary to completely curette out all the inflamed periradicular tissues during surgery, since this granulation-like tissue will be incorporated into the new granulation tissue as part of the healing process. To control the source of irritants in the root canal is far more important than to remove all periradicular tissues affected by the irritants. The successful removal of all irritants from the root canal system results in resolution of pulpally induced periradicular lesions. In the case where the periradicular lesion is caused by endodontic instruments or cytotoxic filling materials placed in the periradicular tissues, removal of these foreign objects is required for resolution of the lesion.     

Using wound care products to promote a healing environment

Healing is characterized by the synthesis of new tissue and scar formation. Despite the complexity of healing with full-thickness injury, the repair process occurs in a predictable manner. There are four basic principles of wound care: (1) debride necrotic tissue and cleanse the wound to remove debris, (2) provide a moist wound healing environment through the use of proper dressings, (3) protect the wound from further injury, and (4) provide nutritional substrates essential to the healing process. Most importantly, any underlying pathophysiology must be treated or the wound will not heal. Products selected to create a healing environment must be chosen thoughtfully and scientific rationale must support their use. Intensive care nurses have the opportunity to get the patient off to the right start by attending to the basic principles elucidated in this article. Accurate wound assessment and appropriate product choices can promote a healing environment. Intensive care of patients includes differentiating wound types and making appropriate wound care product decisions that ultimately affect patient outcomes.     

Formation of Aerobic Granules with Domestic Sewage

The use of aerobic granules in wastewater treatment can reduce the land area that is needed for the treatment of sewage. Until now granulation has been mainly studied using artificial wastewater. Studying the possibility of forming aerobic granules on domestic sewage in a sequencing batch reactor was a logical step in the scaling-up process and development of this technology. Therefore, aerobic granulation was studied using presettled sewage as influent. After 20?days of operation at high chemical oxygen demand (COD) loading heterogeneous aerobic granular structures were observed, with a sludge volume index after 10?min settling of 38?mL?g?1 and an average diameter of 1.1?mm. Applying a high COD load was found to be a critical factor for the formation of aerobic granules on this type of influent. Therefore short cycle times and concentrated wastewater are preferred to form granules in a sequencing batch reactor when low strength wastewater is used. The nutrient removal was not optimized in this study.     

TGF-beta1 influences early gingival wound healing in rats: an immunohistochemical evaluation of stromal remodelling by extracellular matrix molecules and PCNA

The effect of topically applied transforming growth factor beta1 (TGF-beta1) on the rat gingival wound healing process after flap surgery was evaluated by immunohistochemistry for extracellular matrix molecules (ECM), such as tenascin, heparan sulfate proteoglycan (HSPG) and type IV collagen, and for proliferating cell nuclear antigen (PCNA) in fibroblasts. TGF-beta1 solution was applied to the surgical wound experimental sites. Two microg/microl were applied at the time of the operation, and 1 microg/microl at days 1 and 2 after surgery, with contralateral control sites receiving the vehicle alone. Periodontal tissues were histologically examined at 3 and 7 days post-surgery. Tenascin was found to be more strongly stained in the granulation tissue from experimental sites at 3 days post-surgery. At 7 days postsurgery, HSPG-positive areas in granulation tissue had become smaller and there was a prominent proliferation of PCNA-positive fibroblast-like cells and type IV collagen-positive blood vessels. These results suggest that TGF-beta1 applied to surgical wounds influences early proliferation of gingival fibroblast-like cells, the formation of blood vessels, and ECM remodelling. In conclusion, TGF-beta1 application appears to promote granulation tissue formation in periodontal wound healing.     

Periodontal implications in implant treatment planning for aesthetic results

Insufficient hard and soft tissue height and width can be a repercussion of tooth loss or a result of postoperative healing following implant surgery. Insufficient bone can preclude proper implant positioning, while inadequately treated soft tissue will not exhibit a gingival appearance similar to that of the adjacent teeth. If hard and soft tissue discrepancies are not corrected by regenerative techniques, the replaced tooth appears long or overbulked gingivally. In order to create hard and soft tissue harmony, an understanding of the biological variables and periodontal implications is necessary.     

Investigation of protein folding by mass spectrometry

Bone repair by regeneration as we know it continues to undergo changes, with advances approaching that may change our treatment of patients with craniofacial deformities and skeletal defects. Perhaps by the turn of the century, patients born with asymmetric deformities due to lack of growth will be treated early in life by skeletal stretching, and then later in life by skeletal distraction that is followed by use of accelerating factors to assist the healing processes. All of these available modalities are part of the regeneration of new bone formation. The future of such changes is very interesting, and our ability to help our patients will be maximized. We may even look back 25 years from now at bone grafting and find it to be obsolete and crude. It is hoped that with the new modalities being developed, we will not deviate from the use of a bone grafting procedure, which is the workhorse of the craniofacial surgeon. Bone grafting is used by all surgeons working on the craniofacial skeleton despite the problems of unpredictability of healing and an inability to calculate what percentage of the original graft will survive. The transplantation issue will be solved. The problems with donor site morbidity will continue. The use of inorganic bone substitutes will continue to have its limitation, particularly in type II wounds, which we as plastic surgeons see in the craniofacial region. As we redefine our approach to skeletal repair, we may look back and find solutions to some of the major problems we have had. The rapid stretch of soft tissue after facial advancement or structural alteration that is accompanied by a relapse due to the elastic recoil of the soft tissue could be eliminated by gradual distraction. The bone will undergo better functional adaptation when it has a gradual change in structure based on adjustment and molding in a gradual fashion. The problem of donor site morbidity and a prediction formula for bone could be resolved with new bone formation in situ by mineralization of the area under repair. Bone healing enhancers are here to stay and their clinical application will produce a far-reaching better final outcome (Fig. 11).     

Microbiology of tracheal granulation tissue associated with silicone airway prostheses

Granulation tissue formation and contraction is inevitable during the healing of open wounds. The presence of infection and a foreign body, such as a silicone airway prosthesis or other tracheotomy tube, magnifies this response. In airway reconstruction, wound contraction secondary to chronic inflammation is a liability. Cultures of granulation tissue were taken from 12 patients with silicone cannulas of T-Tubes. Polymicrobial colonization predominated, with variable combinations of gram-positive, gram-negative, and anaerobic organisms being present. On the basis of sensitivity data, amoxicillin-clavulanate potassium and ciprofloxacin hydrochloride were chosen as empirical antimicrobials. Anecdotally, impressive decreases in the quantity of granulation tissue were seen. We recommend a prospective trial to more accurately define the role of antibiotics in this setting.     

Developmental stages in experimental liver metastases: relation to invasiveness

We have previously reported that an invasive morphotype can be evoked in a rat colon carcinoma by transplanting it into pre-induced subcutaneous granulation tissue. We have now studied the interaction of the same tumor with liver tissue, which is extremely poor in connective tissue in comparison with the subcutaneous site. Tumor cells were injected into the portal system and the resulting experimental liver metastases were examined by electron microscopy and immunohistochemistry. Early metastases consisted of well-differentiated acini, fully surrounded by connective tissue that was derived from the periportal stroma. In a later stage, this connective tissue was overgrown by tumor cells and, almost immediately, acinar differentiation was lost. Most metastases eventually reached the liver capsule, which reacted by forming a layer of granulation tissue. Only in this layer, we observed invasion by thin tumor cell strands, which were often intimately associated with fibroblasts or with blood capillaries. The tumor cells remained smooth and rounded during this process. After fully penetrating the granulation tissue, the tumor cell strands reached the liver surface, where they formed poorly structured papillary masses that were nearly devoid of stroma. Our observations indicate that, even in a relatively homogeneous organ like the liver, the tumor-host interaction is highly complex and dynamic. They also confirm the notion that granulation tissue stimulates tumor invasiveness. Finally, they show that tumor cells can actively invade host tissues without exhibiting a "fibroblastic" morphology.     

铁矿粉烧结制粒过程颗粒行为研究综述

摘要：烧结原料需经过制粒处理以确保高效低耗的烧结生产,即在水或其他粘结剂的参与下混合料颗粒在相互运动、碰撞中形成粒度更大且粒度分布更窄的聚团颗粒体。制粒效果受制粒设备参数和铁矿粉物理化学性质的影响,因而合适的制粒工艺和铁矿粉优化配置对烧结技术经济指标的改善具有显著作用。阐述了制粒现象的基本理论,综述了制粒过程中颗粒聚结长大的作用力以及颗粒的长大机制,制粒工艺参数如加水量、搅拌动能、制粒时间等和铁矿石的粒度组成、表面性质、颗粒形貌等性质对制粒效果的影响规律。相关结果为系统深入理解铁矿粉制粒过程以及高效生产优质准颗粒提供理论基础。     

Predictability of healing of ischemic leg ulcers by radioisotopic and Doppler ultrasonic examination

In a prospective study of twenty-six patients with ischemic ulcerations of the lower extremity, the predictive reliability with regard to spontaneous wound healing of diabetes, pedal pulses, ankle blood pressure (ABP) as measured by doppler ultrasound, and "leg ulcer scan" as performed by the intra-arterial injection of radioactive albumin was evaluated. The results suggest that only the leg ulcer scan is significantly reliable in predicting the likelihood of spontaneous healing. The following format for the evaluation of the ischemic leg ulcer is therefore suggested: (1) If pedal pulses are present, a three week trial of conservative therapy is indicated before further evaluation. (2) If the doppler ABP is 50 mm Hg or less, the ulcer will not heal spontaneously. (3) Leg ulcer scan is indicated: (a) in the absence of pedal pulses if ABP is less than 50 mm Hg; (b) in the presence of pedal pulses if there is no evidence of spontaneous healing after three weeks of conservative therapy.     

Histological comparison of early wound healing following dense hydroxyapatite granule grafting and barrier placement in surgically-created bone defects neighboring implants

The purpose of this study was to examine early wound healing following grafting of dense hydroxyapatite granules (HA granules) and barrier placement in surgically-created bone defects surrounding implants. Eight healthy adult dogs with an average weight of 15 kg were used in this study. Thirty-two bone defects measuring 4 mm x 4 mm were removed with a surgical bur to form continuous bucco-lingual bone defects and 32 implants (16 titanium [Ti]) and 16 hydroxyapatite-coated [HA]) were then placed into the defects. Four implant groups were created: 1) grafting HA; 2) covering with an expanded polytetrafluoroethylene (ePTFE) membrane; 3) grafting HA and covering with ePTFE membrane; and 4) control (no treatment). Animals were sacrificed 28 days after surgery. Histological sections revealed large amounts of newly-formed bone in all bone defects surrounding the implants treated with ePTFE membranes alone. Fibrous encapsulation of HA granules was observed in the defects of the HA granules grafting group. In the group with grafting of HA granules and covering with ePTFE membranes, small amounts of bone tissue were observed among HA granules, but most HA granules were surrounded with fibrous tissue. Bone defects were completely filled with connective tissue in the control group. There were no differences in the histological findings between Ti and HA-coated implants in all cases. Histomorphometric data disclosed that the presence of HA granules in the bone defects significantly arrested bone formation. Our study suggests that the grafting of dense HA into bone defects surrounding implants will result in fibrous healing during the early healing stage.     

Fractures of the humerus in children

Fractures of the humerus above the distal epiphysis are not common fractures in children. Treatment should be directed toward maintenance of alignment with healing expected without fail. Contrary to experience with adults with the same fractures, children seldom have residual functional or cosmetic problems if one aligns the fractures and protects the healing process.