Activators of SIRT1 in wound repair: an animal model study.

Caloric restriction (CR) and resveratrol activate SIRT1 and induce anti-inflammatory and antioxidant properties. We perform excisional lesion on the dorsum of four groups anesthetized animals: ad libitum-AL diet, AL diet with topical application of 2% resveratrol-Rv, 30% calorie restricted, and finally 30% calorie restricted with 2% resveratrol and we examine CR and Rv effects in wound repair. Restricted animals remained with CR for 31 days. The lesion was performed on day 18 of CR, and resveratrol application was started on day 19. Lesion samples were then collected on days 3 and 10 of treatment for structural, morphometric, and protein analyses. Our results showed that CR and Rv group as well as R group had enhanced numbers of blood vessels, VEGF, fibroblast, birefringent collagen fiber areas in the lesion. We conclude that effects in wound repair suggests that both CR and resveratrol may modulate angiogenesis, fibroplasia, and collagenesis, which could be ascribed to the action of SIRT1.

Heme Oxygenase-1 Promotes Delayed Wound Healing in Diabetic Rats.

Diabetic ulcers are one of the most serious and costly chronic complications for diabetic patients. Hyperglycemia-induced oxidative stress may play an important role in diabetes and its complications. The aim of the study was to explore the effect of heme oxygenase-1 on wound closure in diabetic rats. Diabetic wound model was prepared by making an incision with full thickness in STZ-induced diabetic rats. Wounds from diabetic rats were treated with 10% hemin ointment for 21 days. Increase of HO-1 protein expression enhanced anti-inflammation and antioxidant in diabetic rats. Furthermore, HO-1 increased the levels of VEGF and ICAM-1 and expressions of CBS and CSE protein. In summary, HO-1 promoted the wound closure by augmenting anti-inflammation, antioxidant, and angiogenesis in diabetic rats.

A novel thermosensitive in-situ gel of gabexate mesilate for treatment of traumatic pancreatitis: An experimental study.

Gabexate mesilate (GM) is a trypsin inhibitor, and mainly used for treatment of various acute pancreatitis, including traumatic pancreatitis (TP), edematous pancreatitis, and acute necrotizing pancreatitis. However, due to the characteristics of pharmacokinetics, the clinical application of GM still needs frequently intravenous administration to keep the blood drug concentration, which is difficult to manage. Specially, when the blood supply of pancreas is directly damaged, intravenous administration is difficult to exert the optimum therapy effect. To address it, a novel thermosensitive in-situ gel of gabexate mesilate (GMTI) was developed, and the optimum formulation of GMTI containing 20.6% (w/w) P-407 and 5.79% (w/w) P188 with different concentrations of GM was used as a gelling solvent. The effective drug concentration on trypsin inhibition was examined after treatment with different concentrations of GMTI in vitro, and GM served as a positive control. The security of GMTI was evaluated by hematoxylin-eosin (HE) staining, and its curative effect on grade II pancreas injury was also evaluated by testing amylase (AMS), C-reactive protein (CRP) and trypsinogen activation peptide (TAP), and pathological analysis of the pancreas. The trypsin activity was slightly inhibited at 1.0 and 5.0 mg/mL in GM group and GMTI group, respectively (P<0.05 vs. P-407), and completely inhibited at 10.0 and 20.0 mg/mL (P<0.01 vs. P-407). After local injection of 10 mg/mL GMTI to rat leg muscular tissue, muscle fiber texture was normal, and there were no obvious red blood cells and infiltration of inflammatory cells. Furthermore, the expression of AMS, CRP and TAP was significantly increased in TP group as compared with control group (P<0.01), and significantly decreased in GM group as compared with TP group (P<0.01), and also slightly inhibited after 1.0 and 5.0 mg/mL GMTI treatment as compared with TP group (P<0.05), and significantly inhibited after 10.0 and 20.0 mg/mL GMTI treatment as compared with TP group (P<0.01). HE staining results demonstrated that pancreas cells were uniformly distributed in control group, and they were loosely arranged, partially dissolved, with deeply stained nuclei in TP group. Expectedly, after gradient GMTI treatment, pancreas cells were gradually restored to tight distribution, with slightly stained nuclei. This preliminary study indicated that GMTI could effectively inhibit pancreatic enzymes, and alleviate the severity of trauma-induced pancreatitis, and had a potential drug developing and clinic application value.

[Functional activity of monocytes and mechanisms of iNOS intracellular regulation during wound process].

To investigate the dynamics and mechanisms of iNOS activity during wound process, the peripheral blood monocytes of 22 patients with acute foot wounds were analyzed. The basal and LPS-stimulated nitrites production was estimated at 1, 3-4, 7-10 and 14-18 days of wound process. iNOS activity and its molecular regulation was estimated by the inhibitory analysis. It was shown that since 1 to 3-4 day of wound process the basal and LPS-stimulated activity of iNOS, PDE and 5-LOX were elevated initially and than decreased. The COX and PkC activities increased after 3 days and reached the maximum level at days 7-10. The activity of PkA, which inhibits iNOS, intensively increased form 7-10th to 14-18th days of healing, and was accompanied by arginase-1 stimulation. Thus monitoring of intracellular signaling system can be used for diagnostics and correction of wound healing.

Formononetin accelerates wound repair by the regulation of early growth response factor-1 transcription factor through the phosphorylation of the ERK and p38 MAPK pathways.

Formononetin, a phytoestrogen from the root of Astragalus membranaceus, is used as a blood enhancer and to improve blood microcirculation in complementary and alternative medicine. The present study investigated the influence of formononetin on the expression of early growth response factor-1 (Egr-1) and growth factors contributing to wound healing. Formononetin significantly increased growth factors such as transforming growth factor-beta 1 (TGF-ß1), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) in human umbilical vein endothelial cells (HUVECs). Formononetin also increased the expression of Egr-1 transcription factor by 3.2- and 10.5-fold, compared with recombinant VEGF(125) in HUVECs. The formononetin-mediated 12%-43% increase induced endothelial cell proliferation and recovered the migration of wounded HUVECs. In an ex vivo angiogenesis assay, formononetin produced a larger capillary sprouting area than produced using recombinant VEGF(125). Cell proliferation and migration of HUVECs were also greater in the presence of formonectin than VEGF(125). Western blot analysis of scratch-wounded confluent HUVECs showed that formononetin induced the phosphorylation of extracellular signal-regulated kinase (ERK) and slightly inhibited the phosphorylation of p38 mitogen-activated protein kinase (MAPK). The formononetin-mediated sustained activation of Egr-1 was suppressed by the ERK inhibitor PD98059 and the p38 inhibitor SB203580. PD98059 inhibited the formononetin-induced endothelial proliferation and repair in scratch-wounded HUVECs, SB203580 increased the cell proliferation and wound healing. Formononetin accelerate wound closure rate as early as day 3 after surgery and consistently observed until day 10 after in wound animal model. These data suggest that formononetin promotes endothelial repair and wound healing in a process involving the over-expression of Egr-1 transcription factor through the regulation of the ERK1/2 and p38 MAPK pathways.

Metalloproteinase expression is associated with traumatic wound failure.

BACKGROUND: Matrix metalloproteinases (MMPs) are crucial in the inflammatory and remodeling phases of wound healing. We previously reported the correlation between pro-inflammatory cytokines and timing of successful combat-wound closure. We now extend our studies to investigate the correlation between wound-remodeling MMP expression and wound healing. METHODS: Thirty-eight wounds in 25 patients with traumatic extremity combat wounds were prospectively studied. Surgical debridement with vacuum-assisted closure (VAC) device application was repeated every 48 to 72h until surgical wound closure. Wound effluent and patient serum were collected at each wound debridement and analyzed for five matrix metalloproteinases using the Luminex multiplex system; Millipore Corp, Billerica, MA. The primary outcome was wound healing within 30 d of definitive wound closure. Impairment was defined as delayed wound closure (>21 d from injury) or wound dehiscence. MMP expression was compared between impaired and normal healing wounds. RESULTS: Elevated levels of serum MMP-2 and MMP-7 and reduced levels of effluent MMP3 were seen in impaired wounds (n = 9) compared with wounds that healed (n = 29; P<0.001). Receiver operating characteristic (ROC) curve analysis yielded area-under-the-curve (AUC) of 0.744, 0.783, and 0.805, respectively. CONCLUSIONS: Impaired wound healing is characterized by pro-inflammatory MMP-2 and MMP-7. Serum and effluent concentrations of MMP-2, MMP-3, and MMP-7 can effectively predict the outcome of traumatic war wounds and can potentially provide decision-supportive, objective evidence for the timing of wound closure.

Pancreatic injury.

Injury to the pancreas, because of its retroperitoneal location, is a rare occurrence, most commonly seen with penetrating injuries (gun shot or stab wounds). Blunt trauma to the pancreas accounts for only 25% of the cases. Pancreatic injuries are associated with high morbidity and mortality due to accompanying vascular and duodenal injuries. Pancreatic injuries are not always easy to diagnose resulting in life threatening complications. Physical examination as well as serum amylase is not diagnostic following blunt trauma. Computed tomography (CT) scan can delineate the injury or transaction of the pancreas. Endoscopic retrograde pancreaticography (ERCP) is the main diagnostic modality for evaluation of the main pancreatic duct. Unrecognized ductal injury leads to pancreatic pseudocyst, fistula, abscess, and other complications. Management depends upon the severity of the pancreatic injury as well as associated injuries. Damage control surgery in hemodynamic unstable patients reduces morbidity and mortality.

The serine protease marapsin is expressed in stratified squamous epithelia and is up-regulated in the hyperproliferative epidermis of psoriasis and regenerating wounds.

The trypsin-like serine protease marapsin is a member of the large protease gene cluster at human chromosome 16p13.3, which also contains the structurally related proteases testisin, tryptase epsilon, tryptase gamma, and EOS. To gain insight into the biological functions of marapsin, we undertook a detailed gene expression analysis. It showed that marapsin expression was restricted to tissues containing stratified squamous epithelia and was absent or only weakly expressed in all other tissues, including the pancreas. Marapsin was constitutively expressed in nonkeratinizing stratified squamous epithelia of human esophagus, tonsil, cervix, larynx, and cornea. In the keratinizing stratified squamous epidermis of skin, however, its expression was induced only during epidermal hyperproliferation, such as in psoriasis and in murine wound healing. In fact, marapsin was the second most strongly up-regulated protease in psoriatic lesions, where expression was localized to the upper region of the hyperplastic epidermis. Similarly, in the hyperproliferative epithelium of regenerating murine skin wounds, marapsin localized to the suprabasal layers, where keratinocytes undergo squamous differentiation. The transient up-regulation of marapsin, which closely correlated with re-epithelialization, was virtually absent in a genetic mouse model of delayed wound closure. These results suggested a function during the process of re-epithelialization. Furthermore, in reconstituted human epidermis, a model system of epidermal differentiation, members of the IL-20 subfamily of cytokines, such as IL-22, induced marapsin expression. Consistent with a physiologic role in marapsin regulation, IL-22 was also strongly expressed in re-epithelializing skin wounds. Marapsin's restricted expression, localization, and cytokine-inducible expression suggest a role in the terminal differentiation of keratinocytes in hyperproliferating squamous epithelia.

Loss of protein kinase Cepsilon results in impaired cutaneous wound closure and myofibroblast function.

Cutaneous wound repair requires the de novo induction of a specialized form of fibroblast, the alpha-smooth muscle actin (alpha-SMA)-expressing myofibroblast, which migrates into the wound where it adheres to and contracts extracellular matrix (ECM), resulting in wound closure. Persistence of the myofibroblast results in scarring and fibrotic disease. In this report, we show that, compared with wild-type littermates, PKCepsilon-/- mice display delayed impaired cutaneous wound closure and a reduction in myofibroblasts. Moreover, both in the presence and absence of TGFbeta, dermal fibroblasts from PKCepsilon-/- mice cultured on fibronectin show impaired abilities to form ;supermature' focal adhesions and alpha-SMA stress fibers, and reduced pro-fibrotic gene expression. Smad3 phosphorylation in response to TGFbeta1 was impaired in PKCepsilon-/- fibroblasts. PKCepsilon-/- fibroblasts show reduced FAK and Rac activation, and adhesive, contractile and migratory abilities. Overexpressing constitutively active Rac1 rescues the defective FAK phosphorylation, cell migration, adhesion and stress fiber formation of these PKCepsilon-/- fibroblasts, indicating that Rac1 operates downstream of PKCepsilon, yet upstream of FAK. These results suggest that loss of PKCepsilon severely impairs myofibroblast formation and function, and that targeting PKCepsilon may be beneficial in selectively modulating wound healing and fibrotic responses in vivo.

[The time-dependent changes of phospho-JNK expression during the skin incised wound healing in mice].

OBJECTIVE: To investigate the changes of phospho-JNK (p-JNK) during the incised wound healing of the skin in mice and to explore the rule of the time-dependent change of p-JNK in wound age determination. METHODS: The changes of p-JNK expression in incised skin wound were detected by immunohistochemistry and Western blot. RESULTS: There was a minimal baseline staining of p-JNK in control mouse skin. Changes of p-JNK expression were mainly detectable in neutrophils in the wound specimens from 3 hours to 12 hours after injury. Afterwards, the p-JNK positive cells were mostly mononuclear cells and fibroblasts between post-injury day 1 and day 5, whereas the p-JNK positive cells were mostly fibroblasts between post-injury day 7 and day 14. Morphometrically, the ratio of the p-JNK positive cells to the total increased gradually in the wound specimens from 3 hours to day 1, and maximized at day 1 with a slight decrease from post-injury day 3 to day 5. The ratio showed a second peak in the specimens of day 7, and then decreased gradually from post-injury day 10 to day 14. The changes of p-JNK expression were observed throughout the wound healing stages by Western blot as well, with a peak expression occurring between 12 hour and day 3 after injury. CONCLUSION: p-JNK may play a pivotal role in inducing apoptosis of neutrophils, mononuclear cells, and fibroblasts during skin wound healing and meanwhile, p-JNK may be a potentially useful marker for wound age determination.

Melatonin accelerates the process of wound repair in full-thickness incisional wounds.

The pineal gland hormone melatonin is known to have both anti-inflammatory and immunomodulatory effects. Given this, we propose that melatonin is an ideal candidate to enhance the process of wound healing. The present study assessed the effects of exogenously administered melatonin (1.2 mg/kg intra-dermal), on scar formation using a full-thickness incisional rat model of dermal wound healing. Melatonin treatment significantly improved the quality of scarring, both in terms of maturity and orientation of collagen fibres. An increase in nitric oxide synthase (NOS) activity and therefore nitric oxide production is detrimental during inflammation but is favourable during granulation tissue formation. Melatonin treatment significantly decreased inducible NOS (iNOS) activity during the acute inflammatory phase but significantly increased iNOS activity during the resolving phase. Cyclooxygenase-2, which has been shown to have anti-inflammatory effects, was elevated in the melatonin-treated rats following wounding. In addition, melatonin treatment also accelerated the angiogenic process, increasing the formation of new blood vessels and elevating the level of vascular endothelial growth factor protein expression during granulation tissue formation. Melatonin treatment increased arginase activity (which generates proline, a building block for collagen synthesis) from earlier time points. The protein profiles of hemoxygenase-1 (HO-1) and HO-2 isoforms, vital participants in the repair process, were also up-regulated upon melatonin treatment. This study has therefore demonstrated, for the first time, that melatonin can significantly improve the quality of wound healing and scar formation.

The time-dependent changes of phospho-JNK expression during the skin incised wound healing in mice / 法医学杂志

OBJECTIVE@#To investigate the changes of phospho-JNK (p-JNK) during the incised wound healing of the skin in mice and to explore the rule of the time-dependent change of p-JNK in wound age determination.@*METHODS@#The changes of p-JNK expression in incised skin wound were detected by immunohistochemistry and Western blot.@*RESULTS@#There was a minimal baseline staining of p-JNK in control mouse skin. Changes of p-JNK expression were mainly detectable in neutrophils in the wound specimens from 3 hours to 12 hours after injury. Afterwards, the p-JNK positive cells were mostly mononuclear cells and fibroblasts between post-injury day 1 and day 5, whereas the p-JNK positive cells were mostly fibroblasts between post-injury day 7 and day 14. Morphometrically, the ratio of the p-JNK positive cells to the total increased gradually in the wound specimens from 3 hours to day 1, and maximized at day 1 with a slight decrease from post-injury day 3 to day 5. The ratio showed a second peak in the specimens of day 7, and then decreased gradually from post-injury day 10 to day 14. The changes of p-JNK expression were observed throughout the wound healing stages by Western blot as well, with a peak expression occurring between 12 hour and day 3 after injury.@*CONCLUSION@#p-JNK may play a pivotal role in inducing apoptosis of neutrophils, mononuclear cells, and fibroblasts during skin wound healing and meanwhile, p-JNK may be a potentially useful marker for wound age determination.

Inhibition of p38MAP kinase suppresses fibrogenic reaction in conjunctiva in mice.

PURPOSE: To examine the effects of blocking p38 mitogen-activated protein kinase (MAPK) on post-injury conjunctival scarring in mice. Its effects on the behaviors of cultured subconjunctival fibroblasts were also investigated. METHODS: An in vivo study was conducted using an adenoviral vector carrying a dominant-negative (DN)-p38MAPK gene. A circumferential incision was made in the equatorial conjunctiva by scissors in the right eye of generally anesthetized adult C57BL/6 mice. DN-p38MAPK-expressing adenoviral vector was topically applied. The left control eye received non-functioning adenoviral vector. At 2, 5, and 7 days (each, n=22) the eyes were processed for histological or immunohistochemical examination to evaluate the tissue scarring. The expressions of type-I collagen and growth factors were evaluated by real time-reverse transcriptase-polymerase chain reaction. The effects of p38MAPK inhibitor on the proliferation, migration, and fibrogenic gene/protein expression of cultured human fibroblasts were also studied. RESULTS: The in vivo DN-p38MAPK gene introduction blocked the phospho-p38 expression with reduction of myofibroblast generation and suppression of mRNA expression of connective tissue growth factor (CTGF) and monocyte/macrophage chemoattractant protein-1 (MCP-1) in the mouse-injured conjunctiva. Blocking p38MAPK signal in the fibroblasts by a chemical inhibitor counteracted TGFbeta1's enhancement of expressions of type-I collagen, fibronectin, and CTGF. It also retarded cell migration, but cell proliferation was unchanged. CONCLUSIONS: Inhibiting p38MAPK signal impairs the fibrogenic reaction induced by the subconjunctival fibroblasts in vivo and in vitro, suggesting its potential effectiveness in preventing excessive scarring following glaucoma filtering surgery.

Glial aromatization decreases neural injury in the zebra finch (Taeniopygia guttata): influence on apoptosis.

Emerging evidence suggests a neuroprotective role for oestrogens following damage to the vertebrate brain. Aromatase (oestrogen synthase) is rapidly transcribed and translated in glial cells around areas of neural damage in several vertebrates. However, the potential neuroprotection afforded by locally up-regulated glial aromatase immediately surrounding the injury remains to be tested. Towards this end, individual birds sustained penetrating mechanical injuries via a needle that contained either vehicle or the aromatase inhibitor fadrozole into contralateral hemispheres. Seventy-two hours later, the size of neural injury (as assessed by the extent of necrotic tissue) and the number of apoptotic cells around the injuries were evaluated. The size of injury in the hemisphere injected with fadrozole was significantly larger than the injury caused by vehicle injection. Furthermore, a greater number of apoptotic nuclei were found around the fadrozole-associated lesion relative to vehicle. Finally, constitutively expressed, neuronal aromatase close to the injury site did not differ between hemispheres. We conclude that local inhibition of glial aromatase immediately around the site of injury plays a neuroprotective role in the songbird brain and this protection involves apoptotic pathways. Local up-regulation of glial aromatase may play a pivotal role in the limitation of secondary damage and/or the acceleration of restorative processes following injury to the vertebrate brain.

Nitric oxide and wound repair.

NO produced by both iNOS and eNOS plays many important roles in wound healing, from the inflammatory phase through to scar remodeling. NO has cytostatic, chemotactic, and vasodilatory effects during early wound repair, regulates proliferation and differentiation of several cell types, modulates collagen deposition and angiogenesis, and affects wound contraction. The data accumulated thus far indicates that the timing, level, and site of NO production are highly coordinated in normal wound repair. Defining states resulting from either inadequate substrate or depressed enzyme expression appear to contribute to impaired wound repair; however, NO represents only one factor in the complex process of wound healing. Approaches to improve NO availability may be of therapeutic value.

Incorporation of fluorescent enzyme substrates in agarose gel for in situ zymography.

The currently available methods for the detection of proteases in tissue sections are characterized by limited substrate specificity and low sensitivity and are also cumbersome. We have developed a novel in situ zymography method that uses a synthetic substrate conjugated to a fluorescent tag for detection of proteases in tissue sections. In the presence of active enzyme, the fluorescent tag is cleaved off from the substrate peptide chain resulting in an approximately 100-fold increase in the fluorescent signal. In order to minimize the diffusion of the fluorescent tag, the substrate is incorporated into 1% agarose prior to overlaying onto the tissue section. This method retains the morphological details of the tissue section, is highly sensitive and specific for the designated peptide sequence, and provides information regarding the functional status of the enzyme. Thus, this method could be used for detection and monitoring of enzymatic activity in tissue sections for a variety of applications.

Aromatase expression by astrocytes after brain injury: implications for local estrogen formation in brain repair.

Recent evidence indicates that 17beta-estradiol may have neuroprotective and neuroregenerative properties. Estradiol is formed locally in neural tissue from precursor androgens. The expression of aromatase, the enzyme that catalyses the conversion of androgens to estrogens, is restricted, under normal circumstances, to specific neuronal populations. These neurons are located in brain areas in which local estrogen formation may be involved in neuroendocrine control and in the modulation of reproductive or sex dimorphic behaviours. In this study the distribution of aromatase immunoreactivity has been assessed in the brain of mice and rats after a neurotoxic lesion induced by the systemic administration of kainic acid. This treatment resulted in the induction of aromatase expression by reactive glia in the hippocampus and in other brain areas that are affected by kainic acid. The reactive glia were identified as astrocytes by co-localization of aromatase with glial fibrillary acidic protein and by ultrastructural analysis. No immunoreactive astrocytes were detected in control animals. The same result, the de novo induction of aromatase expression in reactive astrocytes on the hippocampus, was observed after a penetrating brain injury. Furthermore, using a 3H2O assay, aromatase activity was found to increase significantly in the injured hippocampus. These findings indicate that although astrocytes do not normally express aromatase, the enzyme expression is induced in these glial cells by different forms of brain injury. The results suggest a role for local astroglial estrogen formation in brain repair.

Dynamics of the matrix metalloproteinases MMP-1 and MMP-8 in acute open human dermal wounds.

Extracellular matrix degradation during dermal wound healing involves multiple levels of regulation by several enzymes of the matrix metalloproteinase family, their activators, and their inhibitors. This study tested the hypothesis that a temporal pattern of interstitial collagenase appearance occurs during normal dermal wound healing, with matrix metalloproteinase-8 originating from neutrophils appearing earlier than the fibroblast-derived matrix metalloproteinase-1. Open (6 mm) full-thickness dermal wounds, which were covered by transparent occlusive dressings, were made in healthy human volunteers (n = 20). Wound fluids from under the dressings were collected daily through day 8, and wound tissue biopsies were obtained on days 0, 2, 4, 14, and 28. Collagenases were extracted from homogenized tissue biopsies for analysis. Samples were analyzed for the presence of matrix metalloproteinase-1 and matrix metalloproteinase-8 by enzyme-linked immunosorbent assays and by collagenase activity assays using purified types I and III collagen as substrates. In addition, tissue inhibitor of metalloproteinases-1 and matrix metalloproteinase-1/tissue inhibitor of metalloproteinases-1 complexes in wound fluids were measured. Results showed a differential temporal pattern of matrix metalloproteinase-1 and matrix metalloproteinase-8 in wound exudates with peak levels of matrix metalloproteinase-8 occurring on day 4 and matrix metalloproteinase-1 peak levels on day 7. Maximal levels in tissue for both enzymes occurred on day 2. At all time points examined, levels of matrix metalloproteinase-8 were statistically higher than matrix metalloproteinase-1 (100-fold to 200-fold). Tissue inhibitor of metalloproteinases-1 levels declined over time, whereas levels of matrix metalloproteinase-1/tissue inhibitor of metalloproteinase-1 complexes increased to a plateau on day 7. This study provides new evidence implicating matrix metalloproteinase-8 as a major collagenase in healing human dermal wounds. It also shows a temporal pattern in the appearance of the matrix metalloproteinases, tissue inhibitor of metalloproteinase-1, and matrix metalloproteinase-1/tissue inhibitor of metalloproteinases-1 complexes, suggesting that a tightly regulated pattern of expression of matrix metalloproteinases and their inhibitors is essential for normal wound healing in humans.

Myeloperoxidase activity in skin lesions. I. Influence of the loss of blood, depth of excoriations and thickness of the skin.

The measurement of the myeloperoxidase activity was used to quantify the acute granulocyte reaction. A 35% loss of blood resulted in a clear decrease of the myeloperoxidase activity at the edges of experimental incision wounds in rat skin in the first day after inflicting the wounds. After 12 h only about one-third and after 24 h about half of the activity observed in the wounds without the loss of blood remained. After 3 days however the activity had returned to the same level as in the wounds without any loss of blood. In very deep excoriations of the rat skin where only a narrow zone of the dermis was left about double the activity increase was observed after 12 and 24 h when compared to values observed in very superficial or moderate excoriations. When the same type of excoriations were made in both thin inguinal skin and thick dorsal skin then a much higher peroxidase activity increase was observed over 4, 12 and 24 h in the thin inguinal skin than in the excoriations made in the thick dorsal skin.