Light-emitting diode irradiation promotes donor site wound healing of the free gingival graft.

BACKGROUND: This study aims to evaluate the effect of light-emitting diode (LED) light irradiation on the donor wound site of the free gingival graft. METHODS: Rat gingival fibroblasts were chosen to assess the cellular activities and in vitro wound healing with 0 to 20 J/cm(2) LED light irradiation. Seventy-two Sprague-Dawley rats received daily 0, 10 (low-dose [LD]), or 20 (high-dose [HD]) J/cm(2) LED light irradiation on the opened palatal wound and were euthanized after 4 to 28 days; the healing pattern was assessed by histology, histochemistry for collagen deposition, and immunohistochemistry for tumor necrosis factor (TNF)-α infiltration. The wound mRNA levels of heme oxygenase-1 (HO-1), TNF-α, the receptor for advanced glycation end products, vascular endothelial growth factor, periostin, Type I collagen, and fibronectin were also evaluated. RESULTS: Cellular viability and wound closure were significantly promoted, and cytotoxicity was inhibited significantly using 5 J/cm(2) LED light irradiation in vitro. The wound closure, reepithelialization, and collagen deposition were accelerated, and sequestrum formation and inflammatory cell and TNF-α infiltration were significantly reduced in the LD group. HO-1 and TNF-α were significantly upregulated in the HD group, and most of the repair-associated genes were significantly upregulated in both the LD and HD groups at day 7. Persistent RAGE upregulation was noted in both the LD and HD groups until day 14. CONCLUSION: LED light irradiation at 660 nm accelerated palatal wound healing, potentially via reducing reactive oxygen species production, facilitating angiogenesis, and promoting provisional matrix and wound reorganization.

Dietary lipids modulate methylmercury toxicity in Atlantic salmon.

This experiment aimed to study the molecular toxicity of methylmercury (MeHg) in liver, brain and white muscle of Atlantic salmon fed a diet based on fish oil (FO, high dietary n-3/n-6 ratio) compared to an alternative diet mainly based on vegetable oil (VO, low dietary n-3/n-6 ratio). Juvenile salmon were fed decontaminated diets or the FO and VO diets enriched with 5 mg Hg/kg (added as MeHg) for three months. The dietary lipid composition affected the fatty acid composition in the tissues, especially in liver and white muscle. After 84 days of exposure, the liver accumulated three times as much MeHg as the brain and white muscle. Vitamin C content and heme oxygenase, tubulin alpha (TUBA) and Cpt1 transcriptional levels all showed significant effects of MeHg exposure in the liver. TBARS, α-tocopherol, γ-tocopherol, and the transcriptional levels of thioredoxin, heme oxygenase, TUBA, PPARB1, D5D and D6D showed an effect of dietary lipid composition in liver tissue. Effects of dietary lipids were observed in brain tissue for MT-A, HIF1, Bcl-X and TUBA. Interaction effects between MeHg exposure and dietary lipid composition were observed in all tissues. Our data suggest that dietary fats have modulating effects on MeHg toxicity in Atlantic salmon.

Carbon monoxide from heme oxygenase-2 Is a tonic regulator against NO-dependent vasodilatation in the adult rat cerebral microcirculation.

Although the brain generates NO and carbon monoxide (CO), it is unknown how these gases and their enzyme systems interact with each other to regulate cerebrovascular function. We examined whether CO produced by heme oxygenase (HO) modulates generation and action of constitutive NO in the rat pial microcirculation. Immunohistochemical analyses indicated that HO-2 occurred in neurons and arachnoid trabecular cells, where NO synthase 1 (NOS1) was detectable, and also in vascular endothelium-expressing NOS3, suggesting colocalization of CO- and NO-generating sites. Intravital microscopy using a closed cranial window preparation revealed that blockade of the HO activity by zinc protoporphyrin IX significantly dilates arterioles. This vasodilatation depended on local NOS activities and was abolished by CO supplementation, suggesting that the gas derived from HO-2 tonically regulates NO-mediated vasodilatory response. Bioimaging of NO by laser-confocal microfluorography of diaminofluorescein indicated detectable amounts of NO at the microvascular wall, the subdural mesothelial cells, and arachnoid trabecular cells, which express NOS in and around the pial microvasculature. On CO inhibition by the HO inhibitor, regional NO formation was augmented in these cells. Such a pattern of accelerated NO formation depended on NOS activities and was again attenuated by the local CO supplementation. Studies using cultured porcine aortic endothelial cells suggested that the inhibitory action of CO on NOS could result from the photo-reversible gas binding to the prosthetic heme. Collectively, CO derived from HO-2 appears to serve as a tonic vasoregulator antagonizing NO-mediated vasodilatation in the rat cerebral microcirculation.

Green tea polyphenol extract attenuates colon injury induced by experimental colitis.

Inflammatory bowel disease (IBD) is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of green tea extract in rats subjected to experimental colitis induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). At 4 days after DNBS administration the rats were sacrificed. Treatment with green tea extract significantly attenuated diarrhoea and loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, significant reduction of colonic myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) production. Green tea extract also reduced the appearance of nitrotyrosine immunoreactivity in the colon and reduced the up-regulation of ICAM-1.

Delayed administration of alpha-melanocyte-stimulating hormone or combined therapy with BAY 11-7085 protects against gut ischemia-reperfusion injury.

Gut ischemia-reperfusion (I/R) injury is a serious complication of shock. Previously we demonstrated that the administration of alpha-melanocyte-stimulating hormone (MSH) immediately before mesenteric I/R protected against postischemic gut injury. In this report, we tested the therapeutic efficacy of alpha-MSH on gut I/R (60 min ischemia, 6 h reperfusion) injury when given at different time points of reperfusion. Rats underwent sham surgery or were treated with saline or with alpha-MSH that was given 1, 2, or 4 h after superior mesenteric artery clamping. Vehicle-treated I/R rats exhibited severe mucosal injury and increased NF-kappaB DNA binding activity, myeloperoxidase (MPO) activity, and interleukin-6 and heme oxygenase-1 (HO-1) expression. In contrast, rats given alpha-MSH at 1 h of reperfusion, but not 2 h or 4 h, exhibited much less mucosal injury. Rats given alpha-MSH at 1 h or 2 h of reperfusion, but not 4 h, exhibited less MPO activity, NF-kappaB DNA binding activity, and interleukin-6 protein and even higher levels of heme oxygenase-1 than vehicle-treated rats. In addition, we found that combined use of alpha-MSH, a known inhibitor of IkappaBalpha tyrosine phosphorylation, with BAY 11-7085, an inhibitor of IkappaBalpha Ser 32,36 phosphorylation, abrogates gut MPO induction and tissue injury at early and late time points of reperfusion. Thus, alpha-MSH, an endogenous peptide with a favorable side-effect profile, is effective in treating experimental gut I/R injury when given early after the initial ischemia and may represent a candidate therapy for gut I/R in humans in whom recognition and treatment are often delayed.

Dietary restriction attenuates the neuronal loss, induction of heme oxygenase-1 and blood-brain barrier breakdown induced by impaired oxidative metabolism.

Experimental thiamine deficiency (TD) is a model of impaired oxidative metabolism associated with region-selective neuronal loss in the brain. Oxidative stress is a prominent feature of TD neuropathology, as evidenced by the accumulation of heme oxygenase-1 (HO-1), ferritin, reactive iron and superoxide dismutase in microglia, nitrotyrosine and 4-hydroxynonenal in neurons, as well as induction of endothelial nitric oxide synthase within the vulnerable areas. Dietary restriction (DR) reduces oxidative stress in several organ systems including the brain. DR increases lifespan and reduces neurodegeneration in a variety of models of neuronal injury. The possibility that DR can protect vulnerable neurons against TD-induced oxidative insults has not been tested. The current studies tested whether approximately 3 months of DR (60% of ad libitum intake) altered the response to TD. Six month-old ad libitum-fed or dietary restricted C57BL/6 mice received a thiamine-deficient diet either ad libitum, or under a DR regimen respectively for eleven days. The TD mice also received daily injections of the thiamine antagonist pyrithiamine. Control ad libitum-fed or DR mice received an unlimited amount, or 60% of ad libitum intake, respectively, of thiamine-supplemented diet. As in past studies, TD produced region-selective neuronal loss (-60%), HO-1 induction, and IgG extravasation in the thalamus of ad libitum-fed mice. DR attenuated the TD-induced neuronal loss (-30%), HO-1 induction and IgG extravasation in the thalamus. These studies suggest that oxidative damage is critical to the pathogenesis of TD, and that DR modulates the extent of free radical damage in the brain. Thus, TD is an important model for studying the relationship between aging, oxidative stress and nutrition.

Wallerian degeneration and hyperalgesia after peripheral nerve injury are glutathione-dependent.

Experimental inflammatory compression injury to the sciatic nerve (chronic constriction injury, CCI) induces Wallerian degeneration of axons and damages non-neuronal cells at the injury site in association with the development of exaggerated pain-like behavior, or hyperalgesia, to noxious thermal stimuli in the affected anatomical area. We examined whether glutathione, one of whose many functions is an important endogenous antioxidant, influenced resulting neuropathology and hyperalgesia following CCI. Dietary supplementation of the amino acid N-acetyl-cysteine (NAC), a rate-limiting component of glutathione production, beginning 1 day prior to CCI significantly diminished both Wallerian degeneration, measured by quantitative morphometry of myelinated fibers, and thermal hyperalgesia. NAC treatment raised nerve glutathione levels compared to untreated nerves, as indicated using hemeoxygenase-1 (hsp32) immunoreactivity as a marker of glutathione depletion. Because NAC is also known to have antioxidant abilities, studies simultaneously inhibited glutathione synthesis, and results demonstrated no significant reduction in resulting neuropathology or hyperalgesia. Delaying NAC administration to post-injury times consistently decreased hyperalgesia, although not significantly. This study identifies glutathione levels, and presumably oxidative stress, as important determinants of the neuropathological and behavioral consequences of nerve injury, and suggests that dietary supplementation of NAC constitutes an effective pre-emptive therapeutic strategy for situations involving painful nerve injury, such as occurs during surgery.

Enzymatic basis of metal ion alterations of cellular heme and glutathione metabolism.

It is becoming increasingly apparent that the enzymes of heme and GSH metabolism pathways are extremely sensitive to metal ions. It follows that alterations in the activities of the enzymes of heme metabolism are often reflected in the heme dependent cellular functions, particularly those which depend on cytochrome P-450. Moreover, perturbations in cellular GSH levels may alter the biological inactivation of the intermediates of cytochrome P-450 activity normally inactivated by GSH-conjugation. The effects of transition and heavy metal ions on the heme metabolism pathway are perhaps of particular significance when exerted on the two key enzymes of the pathway: the delta-aminolevulinate synthetase, the initial and the rate-limiting enzyme of the heme biosynthetic pathway, and heme oxygenase, the rate-limiting enzyme of heme degradation pathway. The activities of other enzymes of the heme metabolism pathway are also effected by metal ions; the nature of the effect is generally that of inhibition. Similarly, the inhibition by heavy metal ions of the activities of GSSG-reductase, gamma-glutamylcysteine synthetase, and gamma-glutamyl transpeptidase, which are the key enzymes of GSH metabolism, have toxicological significance. However, it is important to recognize that the presently discussed effects of metal ions do not necessarily have negative biological implications. The rather intricate and interrelated effects of metal ions on heme and GSH metabolism pathway under certain circumstances may have positive ramifications.