Wound healing after laser injury to skin--the effect of occlusion and vitamin E

Laser-induced injury of the skin: validation of a computer model to predict thresholds

The exposure and emission limits of ICNIRP, IEC 60825-1 and ANSI Z136.1 to protect the skin are based on a limited number of in-vivo studies. To broaden the database, a computer model was developed to predict injury thresholds in the wavelength range from 400 nm to 20 µm and was validated by comparison with all applicable experimental threshold data (ED50) in the wavelength range from 488 nm to 10.6 µm and exposure durations between 8 µs and 630 s. The model predictions compare favorably with the in-vivo data with an average ratio of computer prediction to ED50 of 1.01 (standard deviation ± 46%) and a maximum deviation of 2.6. This computer model can be used to improve exposure limits or for a quantitative risk analysis of a given exposure of the skin.

Dermatologic Laser Side Effects and Complications: Prevention and Management

The evolution of modern laser and light-based systems has mirrored the demand for clinically effective treatments and the need for safer technologies with reduced postoperative recovery, side effects, and complications. With each new generation of lasers, more selective tissue destruction can be achieved with reduced unwanted sequelae. Patient selection and preparation, operator technique, and expeditious recognition and management of post-treatment side effects are paramount in avoiding complications and patient dissatisfaction. An overview of important variables to consider for dermatologic laser treatments are presented in order to provide a framework to reduce the severity and duration of possible post-treatment side effects and complications.

Wound Healing Properties of Selected Natural Products

Wound healing is a complex process of recovering the forms and functions of injured tissues. The process is tightly regulated by multiple growth factors and cytokines released at the wound site. Any alterations that disrupt the healing processes would worsen the tissue damage and prolong repair process. Various conditions may contribute to impaired wound healing, including infections, underlying diseases and medications. Numerous studies on the potential of natural products with anti-inflammatory, antioxidant, antibacterial and pro-collagen synthesis properties as wound healing agents have been performed. Their medicinal properties can be contributed by the content of bioactive phytochemical constituents such as alkaloids, essential oils, flavonoids, tannins, saponins, and phenolic compounds in the natural products. This review highlights the in vitro, in vivo and clinical studies on wound healing promotions by the selected natural products and the mechanisms involved.

Complementary and integrative treatments: facial cosmetic enhancement

Complementary and integrative medicine is particularly popular among patients undergoing facial cosmetic enhancement. This article reviews the efficacy of the most commonly practiced integrative therapies among this surgical population, with a focus on the most current literature regarding the application or potential for application of these treatments to benefit patients undergoing facial aesthetic surgery. Adverse effects of the most popular herbal and dietary supplements are also reviewed. Finally, the potential for interaction among integrative treatments as well as with conventional pharmacologic therapy is discussed.

Estudo morfológico do efeito radioprotetor da vitamina E (dl-alfa-tocoferil) na reparação tecidual em ratos

Esta pesquisa teve por finalidade avaliar a ação da vitamina E como radioprotetora no processo de reparação tecidual em ratos, após sofrerem um procedimento cirúrgico, que consistiu da produção de uma ferida na região dorsal anterior. Os animais foram divididos em cinco grupos: grupo CO (controle) - constituído de animais em que foi produzida somente a ferida; grupo VE - pré-tratamento com vitamina E (90 UI); grupo IR - irradiação três dias após a cirurgia; grupo VEIR - pré-tratamento com 90 UI de vitamina E e irradiação de suas bordas três dias após a cirurgia; grupo OIR - pré-tratamento com óleo de oliva e irradiação de suas bordas três dias após a cirurgia. A ação radioprotetora da vitamina E foi avaliada pela coloração por hematoxilina-eosina para análise morfológica do tecido de granulação, aos 4, 7, 14 e 21 dias após a cirurgia. A análise dos resultados mostrou que o retardo no processo de reparação tecidual causado por 6 Gy de radiação de elétrons com feixe de 6 MeV não ocorreu no grupo de animais que recebeu vitamina E, mostrando-se esta substância efetiva como radioprotetora.

Effect of short-term and long-term antioxidant therapy on primary and secondary ageing neurovascular processes

Previous studies from our laboratory demonstrated an age-related functional decline in sensory neurones and their modulation of microvascular blood flow (primary ageing processes) that correlated with a deficiency in tissue repair (a secondary ageing process). We also raised the notion of a possible role for free radicals in these age-related changes. The aim of this study was to investigate the impact of antioxidant therapy on modulating sensory neurovascular function and tissue repair with age. Twenty-four-month-old Sprague-Dawley rats were treated with vitamin E for short-term (40 mg/kg, i.p., every other day for 2 weeks) or long-term (for 12 months in advance, 10 g/kg, incorporated in food). These treated rats were assessed for the effectiveness of treatment and tested for their sensory neurovascular function, repair of full-thickness burn, and recovery from hyperalgesia following nerve injury. The results indicate that both short- and long-term vitamin E treatments are effective in improving sensory neurovascular function and in reducing the time required for complete wound closure of full-thickness burn injury. Short-term vitamin E treatment was more effective in protecting against the development of hyperalgesia following nerve injury. An initial increase in wound size and in hyperalgesia was observed in the treated animals, and could reflect possible side effects of the antioxidant therapy and support the importance of free radicals in early stages of the repair process. The data, overall, support the notion that oxidative damage contributes to both primary and secondary ageing processes.

Alpha-tocopherol induces expression of connective tissue growth factor and antagonizes tumor necrosis factor-alpha-mediated downregulation in human smooth muscle cells

The effect of alpha-tocopherol treatment on gene expression in human aortic vascular smooth muscle cells was analyzed by gene expression arrays. The expression of the connective tissue growth factor (CTGF) gene was induced by alpha-tocopherol 1.8-fold in gene array experiments, and similar results were also obtained by RT-PCR (1.7-fold) and at the protein level (1.4-fold). The antioxidants beta-tocopherol and N-acetylcysteine did not induce CTGF gene expression, suggesting a nonantioxidant mechanism for alpha-tocopherol action. Protein kinase C (PKC) inhibition by alpha-tocopherol has been previously described. However, PKC downregulation did not prevent CTGF induction by alpha-tocopherol, and inhibition of PKC activity with several inhibitors did not increase its expression, suggesting an alternative pathway for the alpha-tocopherol effect. On the other hand, tumor necrosis factor-alpha reduced the expression of CTGF, an effect that was reversed by antioxidants. The data suggest that tumor necrosis factor-alpha inhibition of CTGF gene expression is prevented in an antioxidant-sensitive process and that alpha-tocopherol increases CTGF expression by a PKC-independent, nonantioxidant mechanism. Because CTGF stimulates the synthesis of extracellular matrix, the normalization of CTGF gene expression by alpha-tocopherol may accelerate wound repair and tissue regeneration during atherosclerosis.

Effects of antiadhesive agents on the healing of intestinal anastomosis

PURPOSE

The effects of antiadhesive agents on the healing of intestinal anastomosis were investigated.

METHODS

Eighty rats were divided into eight groups. Colotomy and anastomosis were performed to all rats. Saline solution (control), carboxymethylcellulose, aprotinin, verapamil, tenoxicam, cyclosporine, and dextran 70 were administered intraperitoneally. Vitamin E was administered intramuscularly. The rats were killed 15 days later. Anastomotic healing was assessed by bursting pressure and the hydroxyproline content of the anastomotic tissues. The results were evaluated by Mann-Whitney U test.

RESULTS

The mean (+/- standard deviation) bursting pressures of carboxymethylcellulose, cyclosporine, and aprotinin groups (108 +/- 6.73, 122.5 +/-14.39, and 127 +/- 20.23, respectively) were significantly lower than those of the control group (234 +/- 6.19). The mean level of hydroxyproline in the anastomotic tissues was significantly lower in the carboxymethylcellulose and cyclosporine groups (8.92 +/- 0.6 and 8.32 +/- 0.63) than that in the control group (16.33 +/- 0.68).

CONCLUSION

These findings indicate that carboxymethylcellulose and cyclosporine had adverse effects on intestinal anastomosis in rats.

Cutaneous laser resurfacing

Cutaneous resurfacing with the new generation of carbon dioxide and erbium lasers has recently come into favor for the treatment of facial rhytides, photodamage, and scarring. The precise control of these resurfacing lasers over the extent of tissue vaporization minimizes thermal damage to the skin while maximizing therapeutic efficacy. Proper use of resurfacing lasers is contingent upon a complete understanding of their clinical, histologic, and ultrastructural effects, as well as an appreciation of the principles of laser safety. An organized approach to the preoperative, intraoperative, and postoperative management of the patient undergoing laser resurfacing will be provided, including a discussion of prevention and treatment of postoperative side effects and complications. (J Am Acad Dermatol 1999;41:365-89.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the clinical, histologic, and ultrastructural effects of resurfacing lasers and be able to discuss the preoperative, intraoperative, and postoperative management of patients undergoing laser resurfacing.

Care before and after laser skin resurfacing. A survey and review of the literature

BACKGROUND

The extent of the wound healing period and the final outcome of cutaneous laser resurfacing are influenced not only by the treatment protocol and type of laser used but also on care of the skin before and after the procedure.

OBJECTIVE

This project was conducted to determine the pre- and postresurfacing care protocols currently in practice and to research the literature in an effort to clarify which interventions can accelerate wound healing and improve efficacy of the treatment.

METHODS

Three hundred thirty-nine questionnaires were mailed to all dermatology and plastic surgery members of the American Society for Laser Medicine and Surgery (ASLMS). Questionnaires were completed anonymously to decrease respondent bias. Statistical analysis included calculation of percentages and means of the data.

RESULTS

Survey results are discussed and compared with data from the literature for the following interventions: tretinoin cream, glycolic acid cream, hydroquinone, oral prophylactic antibiotics, oral prophylactic antivirals, hydrogel dressings, semiocclusive ointments, topical antibiotics, topical corticosteroids, oral corticosteroids, and dilute acetic acid soaks.

CONCLUSIONS

Many options are appropriate, based on data from past studies, for pre- and postresurfacing skin care. Approximately 73% of the results of the survey correlate with information from the literature. Past studies do provide information to help us select interventions that can improve wound healing and the final cosmetic outcome. Further studies involving resurfacing patients may clarify some of the more complex wound care issues, such as oral prophylactic antibiotics, hydroquinone, and topical vitamins C and E.

Development and biomedical testing of military operational rations

This article gives a brief history of military nutrition research in this century and reviews recent advances made through field testing. Although modern rations are nutritionally complete, ration developers are challenged to improve palatability to promote increased intakes in field training and combat settings. The principal goal for military nutritionists is to identify the optimal macronutrient mix and specific ration components that sustain a soldier's performance in the face of operational stressors such as sleep deprivation, intense physical activity, climatic extremes, and hypobaric hypoxia. Energy expenditures during typical field-training exercises average approximately 4000 kcal/day, whereas energy intakes are usually 3000 kcal/day or less when operational rations are consumed. One way to ameliorate the effects of this shortfall is to provide soldiers with a carbohydrate beverage supplement.