Noninjured Skin Research Articles

Epidermal Development and Wound Healing in Matrix Metalloproteinase 13-Deficient Mice

Degradation of the extracellular matrix, which is an indispensable step in tissue remodelling processes such as embryonic development and wound healing of the skin, has been attributed to collagenolytic activity of members of the matrix metalloproteinase family (MMPs). Here, we employed mmp13 knockout mice to elucidate the function of MMP13 in embryonic skin development, skin homeostasis, and cutaneous wound healing. Overall epidermal architecture and dermal composition of non-injured skin were indistinguishable from wild-type mice. Despite robust expression of MMP13 in the early phase of wound healing, wild-type and mmp13 knockout animals did not differ in their efficiency of re-epithelialization, inflammatory response, granulation tissue formation, angiogenesis, and restoration of basement membrane. Yet, among other MMPs also expressed during wound healing, MMP8 was found to be enhanced in wounds of MMP13-deficient mice. In summary, skin homeostasis and also tissue remodelling processes like embryonic skin development and cutaneous wound healing are independent of MMP13 either owing to MMP13 dispensability or owing to functional substitution by other collagenolytic proteinases such as MMP8.

SKIN NITRIC OXIDE AND ITS METABOLITES ARE INCREASED IN NONBURNED SKIN AFTER THERMAL INJURIES

Local and systemic inflammation can lead to progression of burn wounds, converting second- to third-degree wounds or extending the burn to adjacent areas. Previous studies have suggested that the skin is an important site of production of nitric oxide (NO), synthesized by inducible nitric oxide synthase (iNOS) activation after injury. NO increases in burned wounds, but its formation in noninjured skin has not been investigated. We hypothesized that after severe burns, NO and cytotoxic peroxynitrite would increase in noninjured skin. We also tested the hypothesis that BBS-2, a specific inhibitor of iNOS, would impair NO formation after burn. Thirteen female sheep were randomized into burn injury and smoke inhalation (n = 5, group 1), burn and smoke treated with BBS-2 (n = 3, group 2), and sham (saline treatment, no injury) (n = 5, group 3). All the animals, including the sham-injury group, were mechanically ventilated for 48 h. Samples of nonburned skin and plasma were collected from each animal, and levels of NO and its metabolites were evaluated using a NO chemiluminescent detector. Nitrotyrosine and iNOS expression were determined in the skin by Immunoperoxidase staining, and scoring of masked slides (epidermis, hair follicles, vessels, glands, and stroma) was performed. Skin NO and metabolites significantly increased in the burn and smoke injury group, and this was inhibited by BBS-2. Nitrotyrosine expression also increased significantly in the skin of burned animals. BBS-2 prevented the increase of NOx but not the increase of nitrotyrosine expression in skin. Plasma levels of NO increased in burned animals when compared with sham, but this increase was not significant. The increase of NO and its metabolites after burn in noninjured skin is followed by a significant increase in peroxynitrite, a potent cytotoxic mediator.

Lethal cyanide inhalation with post-mortem trans-cutaneous cyanide diffusion

A 27-year-old worker in a metal processing factory was found dead in a basin, sitting in a solution containing potassium dicyano argentate, potassium cyanide, master batch and brightener ’Elfit 73’. The worker was wearing an acid-resisting overall, rubber boots and a simple dust respirator. While the cyanide concentration in the stomach contents was only 0.05 μg/ml, it was 7.7 μg/g in the lung tissue, 6.3 μg/ml in the heart blood and 31 μg/ml in the femoral vein blood. The different concentrations suggest an initial lethal inhalation of cyanide and an extensive post-mortem diffusion of cyanide through primarily non-injured skin of buttocks and legs. The possibility of a post-mortem cyanide diffusion bars from concluding a vital sign from a high cyanide concentration in a blood sample of one single body site.

Spared nerve injury: an animal model of persistent peripheral neuropathic pain

Peripheral neuropathic pain is produced by multiple etiological factors that initiate a number of diverse mechanisms operating at different sites and at different times and expressed both within, and across different disease states. Unraveling the mechanisms involved requires laboratory animal models that replicate as far as possible, the different pathophysiological changes present in patients. It is unlikely that a single animal model will include the full range of neuropathic pain mechanisms. A feature of several animal models of peripheral neuropathic pain is partial denervation. In the most frequently used models a mixture of intact and injured fibers is created by loose ligation of either the whole (Bennett GJ, Xie YK. A peripheral mononeuropathy in rat that produces disorders of pain sensation like those seen in man. Pain 1988;33:87–107) or a tight ligation of a part (Seltzer Z, Dubner R, Shir Y. A novel behavioral model of neuropathic pain disorders produced in rats by partial sciatic nerve injury. Pain 1990;43:205–218) of a large peripheral nerve, or a tight ligation of an entire spinal segmental nerve (Kim SH, Chung JM. An experimental model for peripheral neuropathy produced by segmental spinal nerve ligation in the rat. Pain 1992;50:355–363). We have developed a variant of partial denervation, the spared nerve injury model. This involves a lesion of two of the three terminal branches of the sciatic nerve (tibial and common peroneal nerves) leaving the remaining sural nerve intact. The spared nerve injury model differs from the Chung spinal segmental nerve, the Bennett chronic constriction injury and the Seltzer partial sciatic nerve injury models in that the co-mingling of distal intact axons with degenerating axons is restricted, and it permits behavioral testing of the non-injured skin territories adjacent to the denervated areas. The spared nerve injury model results in early (<24 h), prolonged (>6 months), robust (all animals are responders) behavioral modifications. The mechanical (von Frey and pinprick) sensitivity and thermal (hot and cold) responsiveness is increased in the ipsilateral sural and to a lesser extent saphenous territories, without any change in heat thermal thresholds. Crush injury of the tibial and common peroneal nerves produce similar early changes, which return, however to baseline at 7–9 weeks. The spared nerve injury model may provide, therefore, an additional resource for unraveling the mechanisms responsible for the production of neuropathic pain.

Expression of inducible nitric oxide synthase in human burn wounds

Nitric oxide is produced by various cell types and can initiate either beneficial or deleterious effects. Because cultured human keratinocytes express an inducible isoform of nitric oxide synthase, it was postulated that keratinocytes within a burn wound would express increased levels of inducible nitric oxide synthase following the injury. Immunohistochemical staining identified the sites of cellular expression and temporal sequence of inducible nitric oxide synthase protein within partial- and full-thickness burns excised from 29 patients. While migrating keratinocytes at the immediate edge of the wounds showed decreased or undetectable levels of inducible nitric oxide synthase, the immediately adjacent proliferative population and upwardly growing keratinocytes from surviving hair follicles showed increasingly greater cytoplasmic staining for inducible nitric oxide synthase at 4-21 days after injury. Noninjured skin showed minimal inducible nitric oxide synthase staining. Within the wound, detectable inducible nitric oxide synthase protein appeared to decrease as keratinocytes assumed a differentiated phenotype in the outer newly resurfaced epidermis, in inner root sheath layers of hair follicles, or in epithelium of eccrine sweat ducts. Within granulation tissue, immunoreactive inducible nitric oxide synthase was detected in capillary endothelium and in arterial smooth muscle layer. Focal increases in inducible nitric oxide synthase expression were noted in association with inflammatory infiltrates. In conclusion, the cellular and temporal distributions of immunoreactive inducible nitric oxide synthase suggest that nitric oxide may play a role in the regulation of wound repair processes beyond the acute burn injury.

Wound status evaluation using color image processing.

An accurate diagnosis of burns and pressure ulcers in the early stages can be made by computerized image processing. This study describes a critical assessment of potential methodologies for noninvasive wound evaluation using a color imaging system. We also developed a method for quantifying histological readings and applied these techniques to a porcine animal model of wound formation. Differences in calibrated hue between injured and noninjured skin provided a repeatable differentiation of wound severity for situations when the time of injury was known. This color analysis allowed statistically significant differentiation of mild, moderate, and severe injuries within 30 minutes after the application of the injury. It was more difficult to distinguish wound severity one to four days later, however the correlation re-emerged when the wounds were five to seven days old. This technique could be adapted for assessing and tracking wound severity in humans in a clinical setting.

Quantitative sensory examination of epidural anaesthesia and analgesia in man: Effects of pre- and post-traumatic morphine on hyperalgesia

The objectives of the study were: 1. (1) comparison of hypoalgesic effects of pre- and post-traumatic epidural morphine (EM) on primary and secondary hyperalgesia, and 2. (2) comparison of EM hypoalgesia in normal and injured skin. Burn injuries (25 × 50 mm rectangular thermode, 47°C, 7 min) were produced on the calves of healthy volunteers, at 2 different days at least 1 week apart. In randomized order, the subjects received 4 mg of EM administered via the L2–L3 intervertebral space on one day and no treatment on the other day. One calf was injured 30 min prior to and the other calf 2.5 h after administration of morphine. Hence, the calf injured prior to morphine administration was a model of postinjury treatment, and the calf injured after morphine administration, a model of pretraumatic treatment. The timing of injuries was identical on the morphine treatment and control days. The injuries induced decrease in heat pain detection and tolerance thresholds within the area of injury (area of primary hyperalgesia) as well as reduction of areas of allodynia for brush and pinprick surrounding the injury (area of secondary hyperalgesia). Both pre- and post-traumatic administration of EM increased heat pain detection and tolerance thresholds, and decreased by approximately 50% the areas of secondary hyperalgesia 2.5 h postinjury. The effects of morphine were naloxone (NAL)-reversible (0.1 mg/kg, i.V.). There was no significant difference between pre- and post-traumatic administration of morphine on the effect of either primary or secondary hyperalgesia. EM increased the heat pain detection threshold more within the injury than at a corresponding non-injured site. There was no significant difference in the effect of morphine on heat pain tolerance in injured and non-injured skin. Following NAL, the areas of secondary hyperalgesia expanded beyond control size. It is suggested that the major effect of EM on secondary hyperalgesia is inhibition of C fibre-mediated activity which maintains the altered response properties of central neurones responsible for secondary hyperalgesia. Possible mechanisms of action of NAL in enhancement of hyperalgesia are discussed.

Alpha-Trinositol inhibits edema generation and albumin extravasation in thermally injured skin.

Pharmacologic attempts to reduce edema generation and albumin extravasation into thermally injured skin have until recently been disappointing unless the drugs (usually antiphlogistic or anti-inflammatory drugs) were given before injury. We have studied the effect of alpha-trinositol (PP56, i.e., 1D-myo-inositol-1,2,6-trisphosphate) given after the injury in an experimental full-thickness 10% TBSA scald burn in anesthetized rats. Total tissue water content (TTW) and albumin extravasation (Ealb) were determined in injured and noninjured skin (series I, n = 12). Interstitial fluid hydrostatic pressure (Pif) was measured in injured skin (series II, n = 14). alpha-Trinositol was administered (alpha-trinositol groups) as an i.v. bolus (40 mg/kg) at 5 minutes after injury followed by an i.v. infusion (1.3 mg/kg/min). In both series a placebo group received burn injury and normal saline in equal volumes instead of alpha-trinositol. Compared with placebo, alpha-trinositol reduced TTW and Ealb as well as the increased negatively of Pif in injured tissue significantly. The effect on Ealb was most prominent, with a reduction from 153.9 +/- 35.6 (SEM) microL/g in the NaCl group to 23.1 +/- 6.3 after alpha-trinositol (p < 0.005). Total tissue water was reduced from 2.51 +/- 0.13 to 2.17 +/- 0.06 mL/g (p < 0.05) and Pif (measured between 21 and 40 minutes postinjury) from -24.7 +/- 4.1 to -3.2 +/- 1.1 mm Hg (p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Human postburn oedema measured with the impression method

The course of tissue swelling in human non-injured skin after burn injury was investigated with a non-invasive impression method that measures force and tissue fluid translocation during mechanical compression of the skin. Time-dependent changes in the fluid translocation and the interstitial-pressure related to impression force were measured on 11 occasions, during 3 weeks, in seven patients postburn. A mathematical model was fitted to the impression force curves and the parameters of the model depicted the time-dependent compartmental fluid shift in the postburn generalized oedema. Tissue fluid translocation increased significantly ( P < 0.05) up to a maximum value after 6 days postburn and declined thereafter. This indicated a continuous increase in the generalized postburn oedema for the first 6 days postburn. Impression force at 3 weeks postburn was significantly lower ( P < 0.001) as compared with the half-day postburn value, indicating an increased tissue pressure during the first days postburn. Parameter analysis indicated a flux of water-like fluid from the vasculature to the interstitial space during the first 6 days postburn. The spread of the values registered between different measurement sites was, however, large.

Synthetic and Biosynthetic Skin Substitutes

The conversion of an open wound to a closed wound is the primary focus in caring for the burned patient. When there are inadequate amounts of noninjured skin to cover the open wound, alternative methods for wound coverage are indicated. Temporary skin substitutes are materials designed to be placed on an open wound to temporarily restore an impaired barrier. These materials may be left on until the wound is healed or until replaced by the patient's own skin. Results of a nationwide survey are reported which identify the various products available for use as skin substitutes. Skin substitutes discussed are pigskin, allograft, and Biobrane. OpSite, Xeroform, and scarlet red are also included. The properties, indications for use, and application procedures for these skin substitutes are described.

Transcapillary colloid osmotic pressures in injured and non-injured skin of seriously burned patients

Thermal skin injury is accompanied by rapid and excessive oedema formation implicating a dramatic increase in the transcapillary fluid transport. In order to clarify the pressure changes occurring across the microvasculature after a thermal skin injury we have measured colloid osmotic pressures (COP) in interstitial fluid (COP i) of injured and non-injured skin as well as in plasma (COP p) from patients suffering major cutaneous burns. Interstitial fluid was collected with a wick-technique and analysed for COP. Measurements were performed as early as 6 h and continued until 56 h after injury. A severe hypoproteinaemia occurred in all patients with a marked reduction in COP p down to about 10 mmHg. Up to 12h post-burn we found a higher COP i in injured skin than in plasma. The first measurement of COP p averaged 9·8 mmHg as compared to an average COP i of 11·1 and 9·3 mmHg in injured and non-injured skin respectively. Measurements performed later than 12 h showed a return of the transcapillary COP gradient towards the normal direction (COP p>COP i). The gradient was considerably less than in a normal situation. Based on the present observations of transcapillary COP it is suggested that colloids should be withheld until the transcapillary COP gradient returns to the normal direction.

Effect of Ultraviolet B Radiation on S-100 Protein Antigen in Epidermal Langerhans Cells

Ultraviolet B (UVB) radiation has been shown to induce significant alterations in both function and surface antigen expression of epidermal Langerhans cells (ELC). In this study we investigated the effect of UVB radiation on ELC marker S-100 protein antigen (S-100 Ag) which is present in the nucleus and cytoplasm of human ELC. A total of 34 sites on 31 volunteers were exposed to 3 MED (minimal erythema dose) of UVB and biopsied at various times up to 7 days after irradiation. Skin from 9 noninjured and 7 slice-wounded subjects served as controls. The avidin-biotin-peroxidase staining technique was used to identify S-100 Ag in sections of formalin-fixed, paraffin-embedded tissue, and the numbers of stained suprabasal dendritic cells were then counted over a 200 basal cell length of interfollicular epidermis. Noninjured skin had 3.56 +/- 3.01 cells, whereas slice-wounded skin had elevated numbers (greater than 10.0 cells) at 1, 24, and 48 h after injury. Following UVB irradiation, a significant (p less than 0.001) increase in antigen-positive cells (14 +/- 3.46) was found at 1 h; this number declined to just below normal at 12 h, but by 48 h returned to and remained at preinjury levels. In contrast to previous observations of the depletion of ELC surface markers by UVB radiation, we demonstrate here that the numbers of S-100 Ag-positive ELC actually increase following comparable doses of radiation. Since this increase occurs so rapidly following both UVB irradiation and slice injury, S-100 Ag may be synthesized or unmasked within the ELC as a response to wounding of the epidermis.

COMPARATIVE HISTOCHEMISTRY OF NON-INJURED SKIN CONNECTIVE TISSUE OF NORMAL AND ASCORBIC ACID DEFICIENT GUINEA PIGS.

Acta Pathologica Microbiologica ScandinavicaVolume 62, Issue 4 p. 465-471 Article COMPARATIVE HISTOCHEMISTRY OF NON-INJURED SKIN CONNECTIVE TISSUE OF NORMAL AND ASCORBIC ACID DEFICIENT GUINEA PIGS STIG D. SCHULTZ-HAUDT, STIG D. SCHULTZ-HAUDT Oslo University Institute of Pathological Anatomy, Rikshospitalet, Oslo, Norway Prof. O. Torgersen, M.D.), Histochemical Laboratory (S. D. Schultz-Haudt, Ph.D.).Search for more papers by this authorSIGURD HJ. FROM, SIGURD HJ. FROM Oslo University Institute of Pathological Anatomy, Rikshospitalet, Oslo, Norway Prof. O. Torgersen, M.D.), Histochemical Laboratory (S. D. Schultz-Haudt, Ph.D.).Search for more papers by this author STIG D. SCHULTZ-HAUDT, STIG D. SCHULTZ-HAUDT Oslo University Institute of Pathological Anatomy, Rikshospitalet, Oslo, Norway Prof. O. Torgersen, M.D.), Histochemical Laboratory (S. D. Schultz-Haudt, Ph.D.).Search for more papers by this authorSIGURD HJ. FROM, SIGURD HJ. FROM Oslo University Institute of Pathological Anatomy, Rikshospitalet, Oslo, Norway Prof. O. Torgersen, M.D.), Histochemical Laboratory (S. D. Schultz-Haudt, Ph.D.).Search for more papers by this author First published: November 1964 https://doi.org/10.1111/apm.1964.62.4.465Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume62, Issue4November 1964Pages 465-471 RelatedInformation