Effect of photodynamic therapy on the healing of a rat skin flap and its implication for head and neck reconstructive surgery

BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) may as adjuvant therapy by used to reduce tumor recurrence in the head and neck with surgery, given intraoperatively after resection. A concern with the use of intraoperative PDT is the possible effect on wound healing, especially on the healing of myocutaneous skin flaps, which are widely used to reconstruct defects following resections for head and neck cancer. STUDY DESIGN/ MATERIALS AND METHODS: A flap, based on the inferior epigastric artery, was prepared in thirty male Lewis rats. Group I did not receive any further treatment but the wound was left open for 20 minutes. Group II was injected with 5mg/kg Photofrin, 48 hours prior to the operation and also did not receive any further treatment. The wound bed and wound borders of group III were treated with 630nm light of different dosages, delivered by an argon dye laser. Animals in group IV received 5mg/kg Photofrin 48 hours prior to the operation and their wound beds were treated with the same light dosages as group III. After the treatment all flaps were replaced into the wound bed and the incisions were closed. Biopsies for histological analysis were taken at several time points; and on day 21, biopsies for wound tensile strength measurements were taken. RESULTS: The wound healing in group I, II, and III appeared normal and there were no differences seen between these groups. Also, the tensile strength did not differ significantly. The flaps of group IV showed serous effusion, epidermal necrosis, and weaker tensile strength (P = .04 and .02 for the light doses of 50 J/sq cm and 75 J/sq cm respectively) at a specific time point. CONCLUSION: The results of this study demonstrate that PDT given immediately before flap reconstruction will result in delayed wound healing. These results should be considered when contemplating the use of PDT as adjuvant intraoperative therapy for tumor surgery requiring flap reconstruction after ablative surgery.     

Coronary angioplasty, bypass surgery, and retransplantation in cardiac transplant patients with graft coronary disease

BACKGROUND AND OBJECTIVE: Prior studies of laser tissue soldering (LTS) of epithelial skin have shown poor wound strength in the short-term; however, we hypothesize that greater tensile strength and healing properties will result from directing laser energy to the dermal aspect of the skin. The current study compares wound strength and histology in a rat skin flap model of epithelial and dermally applied LTS. STUDY DESIGN/MATERIALS AND METHODS: Skin flaps (2.5 x 4 cm) were raised and bisected on the dorsum of Sprague-Dawley rats. The center line of bisection was closed from a dermal approach by LTS (LTS-D, diode laser 15.9 W/cm2 + Columbia solder), the upper incision by epithelial LTS (LTS-E), and the lower incision by suturing (7-0 Vicryl). Wound skin strips (1-2 mm x 10 mm) were studied immediately (N = 14) and at 3 (N = 57), 7 (N = 31), and 10 (N = 28) days postoperatively and were subjected to tensiometric analysis. Histologic staining with hematoxylin and eosin and Mallory's trichrome methods were used to define wound architecture. RESULTS: No wound dehiscences were noted in any group. Greater immediate tensile strength was noted in wounds closed by LTS-D (521 +/- 61 g/cm2) versus LTS-E (342 +/- 65 g/cm2); however, this difference was not statistically significant (P = .08). By 3 days, both LTS-D (476 +/- 55 g/cm2) and LTS-E (205 +/- 37 g/cm2) maintained their initial strength; however, LTS-D and sutured (436 +/- 49 g/cm2) wounds were stronger (P < .05) than LTS-E. At 7 and 10 days, LTS-D (2,433 +/- 346 g/cm2 and 3,100 +/- 390 g/cm2) showed superior tensile strength (P < .05) compared to both LTS-E (1,542 +/- 128 g/cm2 and 2,081 +/- 219 g/cm2) and suturing (1,342 +/- 119 g/cm2 and 1,661 +/- 115 g/cm2). Histologic analysis of LTS-D wounds at 3 days showed full-thickness tissue apposition, complete epithelialization, and minimal inflammation or thermal injury. At 7 days, solder was present in the wounds. In contrast, LTS-E wounds at 3 days displayed lack of epithelialization secondary to thermal injury and partial-thickness tissue apposition. However by 7 days, epithelialization was complete with moderate scarring, and no solder was seen. Sutured samples appeared similar to LTS-D, except for poorer tissue apposition at the hypodermis. CONCLUSION: Our results show that skin flap wound healing after dermal LTS is superior to epithelial LTS and emphasizes the importance of site specificity in the utilization of this operative technique in reconstructive surgery.     

Skin flap closure by dermal laser soldering: a wound healing model for sutureless hypospadias repair

OBJECTIVES: Laser tissue soldering (LTS) with the diode laser and human albumin-hyaluronate-indocyanine green solder is a safe and effective method of providing an immediate leak-free closure during hypospadias repair. In this report, we compare the physiology, histology, and immunohistochemistry of wound healing following LTS and suturing in a rat skin flap model. METHODS: A 4 x 5-cm skin flap was raised and bisected (4 cm) on the dorsum of 48 Sprague-Dawley rats. The central wound was either closed from a dermal approach by suturing or LTS or left open, and studied at 0, 3, 5, 7, 10, 14, and 21 days postoperatively. An intraoperative comparison was made between suturing and LTS with respect to operative time. Postoperatively, flaps were excised for tensiometric analysis, and sections were stained with hematoxylin-eosin to define wound architecture. Resting skin temperature, laser exposed temperature without solder, and maximum temperature with solder (one drop) were measured at the level of the deep dermis, superficial striated muscle layer, and within the solder. Mean peak temperatures were recorded during a 1-minute laser activation time. RESULTS: Mean continuous suturing time (4.9 +/- 1.1 minutes) was significantly (P < 0.001) faster than either LTS (7.7 +/- 0.77 minutes) or discontinuous suturing (8.2 +/- 0.62 minutes). Two seromas (sutured) and two instances of partial wound dehiscence (1 sutured, 1 LTS) were noted. Tensile strength was increased significantly (P < 0.001) for up to 5 days in the LTS group, but was equal to suturing at 7 and 10 days. Immediate tensile strength after LTS was equivalent to a 7-day healed wound. At 14 days, wounds initially left open and those closed by LTS were stronger than sutured wounds (P < 0.05). There was no evidence of thermal injury or foreign body reaction in the LTS group. Solder was incorporated within the dermis in all wounds at 21 days. Laser activation of solder resulted in significant increases in temperature at all three tissue levels: 65.0 +/- 5.2 and 69.9 +/- 6.8 degrees C in the deep and superficial skin (no significant difference between the two), and 101 +/- 15.6 degrees C within the solder (P < 0.001 versus superficial and deep skin). CONCLUSIONS: Our results indicate that sutureless dermal LTS of skin flaps provides increased tensile strength for up to 7 days, with relatively greater tensile strength provided within the first 3 days. Our laser technique does not appear to alter the normal wound healing process. Rather, solder-tissue interaction initially, and extracellular matrix infiltration of solder later, provide the basis for improved wound strength. For hypospadias repair using skin flaps, these wound attributes may permit sutureless surgery.     

Laser-induced photoacoustic effects in the dentin]

To study photoacoustic effects in dentin caused by UV-laser ablation, laser-induced shockwaves were measured using piezoelectric PVDF films. Above the tissue-specific energy threshold for photoablation the amplitude of the acoustic shock waves is proportional to the applied laser energy density. Laser energy densities of 2 J/cm2 cause pressure amplitudes of 50 bar, densities of 20 J/cm2 cause pressure amplitudes of 1000 bar. To avoid microcracks in dentine the maximum laser energy density to prepare dentin should be limited to approximately 20 J/cm2.     

Oxytocinergic innervation to the upper thoracic sympathetic preganglionic neurons in the rat. A light and electron microscopical study using a combined retrograde transport and immunocytochemical technique

A new pH indicator, seminaphthofluorescein (SNAFL)-calcein acetoxymethyl ester, was used for intracellular pH (pHi) measurement in living MDCK cells with a laser scanning confocal microscope (LSCM) equipped with an Argon/Krypton laser and dual-excitation and dual-emission (FITC/Texas Red) filter set. SNAFL-calcein excitation maxima are approximately 492/540 nm (acid/base) and emission maxima are approximately 535/625 nm (acid/base) with a pKa value at approximately 7.0. The absorption/emission spectra of SNAFL-calcein indicate that the ratio of emission intensities of its basic/acidic forms is pH dependent. With an Argon/Krypton LSCM, we were able to monitor the acidic and basic forms of this dye simultaneously using dual-excitation (488/568 nm) and dual-emission (525-614 nm/> or = 615 nm) wavelengths (lambda s). The simultaneous dual-excitation/emission LSCM system allows for efficient recording of pHi dynamics (time resolution approximately 1 sec) in living cells. We have analyzed emission stability of the dye at different temperatures (22 degrees C and 37 degrees C) and constant pH, and at the same temperature (22 degrees C) but various pHs (6.6, 7.0, and 7.4). Bleaching rate is slightly higher at 37 degree C than that at 22 degrees C. The basic form of the dye (lambda Em approximately 625 nm) has a slightly higher bleaching rate than the acidic form (lambda Em approximately 535 nm) in standard culture medium (pH 7.3) at either 22 degree C or 37 degrees C. The pHi in MDCK cells calculated from ratio images (535 nm/625 nm) was 7.19 +/- 0.03 (mean +/- SEM, n = 20). Calibration experiments show that the useful pH range of SNAFL-calcein appears to be between 6.2 and 7.8, as the dye is difficult to calibrate outside this pH range.     

Cervical spine abnormalities in professional singers

BACKGROUND AND OBJECTIVE: The purpose of this study was to determine irradiation parameters of a 780 nm low power CW diode laser (6.5 mW) leading to enhanced proliferation of cultured normal human keratinocytes (NHK). The possible role of reactive oxygen species (ROS) in this response was evaluated. STUDY DESIGN/MATERIALS AND METHODS: NHK were exposed to a single dose of 0 to 3.6 J/cm2 (0-180 sec) of irradiation. Proliferation parameters studied were: incorporation of 3H-thymidine during 6-24 hr following irradiation; percentage of dividing cells and number of cells, 24 hr and 48 hr following irradiation, respectively. RESULTS: Proliferation of NHK exposed to 0.45-0.95 J/cm2 was significantly enhanced by 1.3-1.9-folds relative to sham-irradiated controls, as inferred from parameters studied. Exposure to other energy densities was considerably less effective in enhancing proliferation parameters. Added enzymatic antioxidants, superoxide dismutase or catalase, scavenging superoxide anions and H2O2, suppressed this enhanced proliferation. Added scavengers (alpha-tocopherol acetate, scavenging lipid peroxidation, or sodium azide, histidine, mannitol, scavenging singlet oxygen, superoxide anions, and hydroxyl radicals, respectively), or N-acetyl cysteine, the thiol-reducing agent, suppressed the response, but to different extents. CONCLUSIONS: The results indicate that 780 nm low power diode laser irradiation enhanced keratinocytes proliferation in vitro, with an apparent involvement of ROS in this response, and comparably, might be used to promote their proliferation in vivo to enhance wound healing.     

Does a good correlation exist between the figures for fasting capillary blood glucose and glycosylated hemoglobin?

In order to investigate the function of epidermal growth factor (EGF), the following experiments were performed. Thirty white rats were chosen and divided into 3 groups. In the back of each rat, two 2 cm x 2 cm wounds were made bilaterally, the skin and subcutaneous tissue was removed. EGF were used in one of the two wounds randomly, while those without EGF usage in control. After 1, 2 and 3 weeks, the rats were sacrificed. The area of the wounds was measured, and the healing time of each wound was recorded. The results showed that the healing time of EGF group was 14.6 days while that of control group was 18.5 days (P < 0.01). Furthermore, the DNA, protein and hydroxyproline contents of EGF group were higher than those of the control group (P < 0.01). It was suggested the EGF could accelerate wound healing and shorten the healing time.     

Chromophore enhanced laser welding of canine ureters in vitro using a human protein solder: a preliminary step for laparoscopic tissue welding

Laser welding of the genitourinary tract has the potential advantage of forming an immediate watertight seal. It may obviate the need for sutures, eliminate the inherent lithogenic reaction to suture, and potentially improve healing. In the current study we employed a KTP-532 laser in vitro to weld canine ureters. Ureters were transected over a stent and immediately repaired using the KTP-532 laser (power density 7.14 W/cm.2, spot size = 0.5 cm.) alone or in combination with different tissue solders. Solders consisted of 40% human albumin alone or with the addition of iron oxide or fluorescein as light absorbing dyes (chromophores). Following the repairs, intraluminal bursting strength and the total energy required to complete the repairs were measured. The KTP laser alone was not able to achieve a satisfactory repair. Successful ureteral repairs were achieved in all solder groups while maintaining ureteral continuity at supraphysiologic pressures.     

ArF-excimer laser-induced secondary radiation in photoablation of biological tissue

Secondary radiation, emitted during and after the irradiation of corneal, dermal, and dental tissue by an ArF-excimer laser (193 nm), was qualitatively and quantitatively characterized. Emission of secondary radiation was found in the range of 200-800 nm. The intensity of secondary radiation in the range of 200-315 nm (UVC and UVB) is approximately 20% of the total intensity at high laser fluences (> 2 J/cm2), and approximately 50% at moderate laser fluences (< 500 mJ/cm2); 10 muJ/cm2 in the UVC and UVB were measured at the sample surface, at fluences (< 1J/cm2) which are of relevance for clinical procedures on soft tissues. In dental tissue processing, very high fluences (> 5 J/cm2) are required. As a consequence, laser-induced plasma formation can be observed. Secondary radiation can be used as a visible guide for selective removal of carious altered tissue. The data we have found might be of assistance in estimating potential hazards for future mutagenic studies in the field.     

Determining energy density distribution in laser irradiation fields, generated by the LILAB system

Laser energy densities of less than 1 J/cm2 had no apparent effect on human tissues, while energy densities of more than 4 J/cm2 resulted in tissue damage. For non-punctiform laser applications, therefore, a laser beam distribution system that provides a homogeneous energy density distribution is of advantage, since such a system permits safe application of the laser in the effective therapeutic range. Conventional laser scanners for medical use have been reported to produce grossly inhomogeneous energy density distributions. The new LILAB system, which is a very fast laser beam distribution system, readily generates application fields of different configuration with high homogeneous energy density distribution. The article presents an example of a randomly selected application field, in which the energy densities at the edges and at the centre are compared.     

The minimal sequence needed to define a functional DNA terminator in Bacillus subtilis

BACKGROUND: We wished to determine whether transcutaneous oximetry or laser Doppler flowmetry (LDF) could identify patients at risk for wound failure after conservative, limb-sparing surgery for extremity sarcomas. METHODS: Studies were performed on postoperative days (PODs) 1, 4/5, 7, and 9. Measurements of transcutaneous oxygen pressure (tcPO2) were taken at breathing room air (BL) and 100% oxygen (rate tcPO2). LDF measurements were taken at multiple sites along the wound, and a perfusion index was calculated. RESULTS: Twenty-four patients were studied. Four (17%) had nonhealing wounds. There was no difference in tcPO2 (BL) values between healed and nonhealing wounds. Measurement of rate tcPO2 on POD 1 was significantly lower in the nonhealing wounds than in those with normal healing (28.5 +/- 12.1 mm Hg vs 14.3 +/- 16.2 mm Hg, mean +/- SD, p = 0.03). Rate tcPO2 values increased significantly in healing wounds from POD 1 to PODs 7 and 9 (p = 0.006, p = 0.009). This increase was absent in nonhealing wounds. A clear separation was noted in rate tcPO2 values between groups, with a minimum rate tcPO2 value recorded in a healed wound of 9 mm Hg/min, compared with the maximum value in a nonhealing wound of 7 mm Hg/min. The LDF perfusion index failed to predict wound healing at any of the measured time points. CONCLUSIONS: This study showed that measurement of tcPO2 during oxygen inhalation can accurately predict wound healing in patients after excision of an extremity sarcoma.     

Microhardness and scanning electron microscopy analysis of Nd:YAG laser and acid treatment effects in dentin

Laser irradiation at and above parameters producing the modification threshold for dentin causes structural changes to the dentin surface. This study determined the microhardness of dentin before and after laser modification and acid treatment using a repeated-measures design. Seven dentin sections (4 mm in thickness) were cut from freshly extracted non-carious third molars using a diamond saw. The middle occlusal third was used as the test dentin surface. One section served as a control (C); three received laser modification (L) and then acid treatment (L + A); and three received acid (A) and then laser treatment (A + L). Laser modification was made using a pulsed (120 microseconds) fiber-optic-delivered (500 microns diameter) Nd:YAG (lambda = 1.06 microns) laser at the physical modification threshold of 207 J/cm2. Acid treatment consisted of 10% nitric acid applied for 45 seconds. Twenty Knoop indentation microhardness measurements (KHN) were obtained using 300 g force engaged for 15 seconds for each section before and after each treatment (n = 400). Knoop microhardness values recorded: C = 62 +/- 3; L = 149 +/- 35; A = 24 +/- 5; L + A = 40 +/- 16; and A + L = 33 +/- 5. Multifactor-repeated measures, with analysis of variance (ANOVA; p < or = 0.05), indicated significant differences between all treatment groups. Scanning electron microscopy analysis of dentin surfaces documented unique surface morphology for all treatment conditions. Laser modification of dentin before or after acid treatment increased dentin microhardness.     

Circadian entrainment and phase shifting in mammals with melatonin

BACKGROUND: Diathermy procedures are indispensable in interventional endoscopy. Argon beam coagulation is an innovative no-touch electrocoagulation technique in which high-frequency alternating current is delivered to the tissue through ionized argon gas. METHOD AND PATIENTS: Before clinical application, we conducted in-vitro studies to investigate the depth and diameters of tissue coagulation in fresh operative specimens from the stomach, small intestine and colon. Five different power/gas flow settings between 40 and 155 W and 2 and 7 l/min were used. The impact time (1-10s) and the incident angle of the probe (45 degrees and 90 degrees) were also varied. The maximum depth of necrosis was 2.4 mm, the maximum diameter 1.1 cm. No perforation occurred even in critical areas such as the colon and duodenum. We therefore performed argon beam coagulation in 66 consecutive patients. Two power/gas flow settings of 40 and 70 W and 2 and 3 l/min, respectively, were used. The impact time and incident angle were varied individually. RESULTS: In 49 of the 50 patients with oozing haemorrhage from angiodysplastic lesions, polypectomy sites, erosions or ulcers or oozing of blood due to vascular penetration by tumours, definitive haemostasis was achieved in one to two sessions. In all 11 patients with residual sessile adenoma tissue, complete removal was possible. Oesophageal patency was restored in all five patients with stenosing tumours. In one patient with angiodysplasia of the caecal pole, an asymptomatic accumulation of gas in the submucosa was observed which resolved spontaneously. In two patients with extensive oesophageal carcinoma, there was a transitory--also asymptomatic--accumulation of gas in the mediastinum and peritoneal cavity but no evidence of perforation. CONCLUSION: Argon plasma electrocoagulation is an effective and relatively low-cost alternative to laser therapy in gastrointestinal endoscopy.     

How to manage quality assurance at laboratories? A specialist''s examination is necessary in the specialty of clinical chemistry

Two thousand plus (2,000+) assisted laser surgical procedures were performed between July 1986 and November 1993. Multiwavelength specialties: Argon, CO2 and NdYAG usage include: general surgery, thoracic surgery, neurosurgery, ophthalmology, and gynecology. 65% of the patients were female whose ages range from 6 to 105 years. Endoscopic vs. handheld procedures ratios 1:1. In 95% of the cases attended, the procedures were performed for benign conditions. The office hospital usage distribution was 60-40%. The office morbidity was 0.8% (16 out of 2,000 cases) and a mortality of 0.15% (3 out of 2,000 cases). A reported 100% safety compliance was seen. Laser assisted surgery is a safe, effective and reliable option available to the surgeon's armamentarium. It appears that in some procedures it will allow shorter hospital stays and an earlier return of the patient to his/her normal routine.     

The effect of octreotide on wound healing: an in vitro and in vivo experimental study

OBJECTIVE: To investigate the effect of octreotide on wound healing. DESIGN: Experimental studies in vitro and in rats. SETTING: Teaching hospital, Israel. MATERIAL: Cultured human diploid fetal fibroblasts, and 36 male Wistar rats. INTERVENTIONS: Octreotide was added to cultures of fibroblasts in doses of 2, 10, 30, 60 and 120 ng/ml and fibroblasts were counted after 2, 4, and 6 days. Intestinal anastomoses were made in 36 rats. Rats in the octreotide group (n = 18) were given subcutaneous injections of 0.25 microg/kg twice daily and 6 rats were killed at 3, 7, and 14 days. The control group were given injections of saline. Anastomotic bursting pressures and hydroxyproline content were measured at each of the three times. MAIN OUTCOME MEASURES: Fibroblast counts, anastomotic bursting pressures, and hydroxyproline concentrations. RESULTS: Octreotide did not inhibit fibroblast proliferation in any of the doses at any of the time periods. The anastomotic bursting pressure was slightly higher in the octreotide group at each of the time points, but not significantly so, and there was no difference in hydroxyproline content between the octreotide and control groups. Octreotide did not inhibit wound healing either in vitro or in vivo.     

Seizure induced C-Fos mRNA in the rat brain: comparison between young and aging animals

Although there are many publications on the usefulness of magneto-therapy, discrepancies exist about the utility of electromagnetic fields in skin wound healing. The objective of this work was to study the effect of electromagnetic fields on wound healing in rats. Thirty six male Wistar rats were used; a rectangular lesion was made in the back of each animal (4.2 cm x 2.3 cm). They were divided into 3 groups: group C (control) with sham treatment; group C50, treated with continuous electromagnetic fields of 5 mT (50 Gauss) and group P200, treated with pulsed electromagnetic fields of 20 mT (200 G). The treatments were of 30 minutes a day during 21 days. The corporal weights (Table 1) and the wound longitudinal and transversal maximal axis (Figures 1, 2) were weekly recorded and the data was evaluated by analysis of variance. On day 14, the P200 group showed the maximal longitudinal axis which was smaller than that of group C (p < 0.01). On day 21 in both treated groups the maximal longitudinal axis was smaller than that of group C (p < 0.01); besides the axis was smaller in the P200 group than in the C50 group (p < 0.05). No statistical differences were observed in the remaining data. The results showed a facilitating effect of electromagnetic fields on wound healing in rats. Pulsed electromagnetic fields seem to have a precocious and larger healing effect than continuous electromagnetic fields.     

Effects of transforming growth factor beta on corneal epithelial and stromal cell function in a rat wound healing model after excimer laser keratectomy

BACKGROUND: Transforming growth factor beta (TGF-beta) regulates extracellular matrix deposition, cell proliferation, and migration, and is expressed in cornea. TGF-beta is thought to be involved in the corneal wound healing process. METHODS: The central corneal area (3 mm in diameter) of Lewis rats was ablated using PTK mode excimer laser and the wound healing process was observed at 12 and 24 h and 2, 5, 10, and 30 days after treatment. The expression of TGF-beta 1, -beta 2 and -beta 3, TGF-beta type I and type II receptors, alpha 3, alpha 5, beta 4 integrin subunits, laminin and fibronectin was studied immunohistochemically. Antibody neutralizing TGF-beta 1, -beta 2 and -beta 3 was administered intraperitoneally, 50 micrograms daily, for 5 days after the laser treatment to investigate the effects of TGF-beta function blockade. RESULTS: At the leading edge of the regenerating epithelium, no TGF-beta type I and type II receptors and beta 4 integrin subunits were expressed after 24 h. Regenerating epithelium covered the ablated area after 2 days. An abnormal fibrotic layer was formed in the subepithelial area. This layer contained round-shaped cells in the stroma in the early stage (2-5 days after laser ablation) and spindle-shaped fibroblast-like keratocytes after 10 days. Laminin and fibronectin expression increased in the fibrotic layer. The increased stromal cells expressed TGF-beta isoforms and TGF-beta receptors. Neutralizing TGF-beta inhibited the stromal cell increase in the laser ablated area after 5 days. CONCLUSION: TGF-beta may be involved in epithelial cell migration and stromal cell reaction during the corneal wound healing process after excimer laser ablation in rat models.     

Suicidality and aggressive behaviour

Delayed wound healing is one of the complications of diabetes mellitus, exhibited by increased wound collagenase and decreased granulation tissues. The current study compared wound healing in normal and diabetic rats, and the effects of topically applied 1% or 3% concentrations of chemically modified tetracycline-2 (CMT-2) on 6-mm circular full-thickness skin wounds healed by secondary intention. On day 7 after wounding, tissues were removed for biochemical analysis and histology. The wound granulation tissue hydroxyproline was less in the untreated diabetic rat with increased collagenase and gelatinase. Treating the diabetic rat wounds with 3% CMT-2 increased the wound hydroxyproline and decreased activities of gelatinase and collagenase. There was a delay in wound filling by granulation tissue in diabetic rats. In CMT-2-treated diabetic rats, the volume of granulation tissue was greater than that in untreated diabetic rats. CMT-2 appears to normalize wound healing in diabetic rats and may be a valuable adjunct in the treatment of chronic wounds.     

Medial prefrontal lesion deficits involving or sparing the prelimbic area in the rat

OBJECTIVE: Evaluate wound healing of incisions created by the scalpel, electrocautery, CO2 laser, and potassium titanyl phosphate (KTP) laser in the upper aerodigestive tract in an animal model. STUDY DESIGN: Prospective randomized study in an animal model. METHODS: Postoperative oral intake, histologic depth of injury, and tensile mechanical strength were measured in rat tongues after creating incisions using a scalpel, electrocautery, CO2 laser, and KTP laser. An unpaired, two-tailed Student's t-test was used to compare results between the experimental groups. RESULTS: Oral intake, indirectly assessed by postoperative weight loss, by the third postoperative day was significantly decreased in the electrocautery (P = 0.004), CO2 laser (P = 0.001), and KTP laser (P = 0.0001) groups as compared with the scalpel group. The depth of the wound healing, as assessed by histologic examination, was successively greater for the scalpel (75 +/- 13 microm), electrocautery (110 +/- 10 microm), CO2 laser (145 +/- 10 microm), and KTP laser (195 +/- 23 microm) groups. However, this difference was only statistically significant for the CO2 laser (P = 0.006) and KTP laser (P = 0.01) groups relative to the scalpel group. Wounds created by the KTP laser had the lowest strength (76.5 +/- 6.9 kPa) as compared with the CO2 laser (156 +/- 28.4 kPa), electrocautery (153 +/- 15.7 kPa), and scalpel groups (249 +/- 61.8 kPa). This difference was only statistically significant for the KTP laser group (P = 0.02) when compared with the scalpel group. CONCLUSIONS: Wounds created in the upper aerodigestive tract of rats by scalpels result in the least postoperative weight loss, tissue destruction, and decrease in tensile strength, whereas wounds created by the KTP laser demonstrated a significantly greater postoperative weight loss, depth of wounding, and decrease in tensile strength.     

Erbium laser resurfacing: current concepts

Laser skin resurfacing has enjoyed great popularity in recent years with the introduction of computerized, pulsed carbon dioxide lasers. However, the morbidity and side effects of carbon dioxide lasers have stimulated a search for alternative methods of skin remodeling. The erbium:YAG laser can be successfully used for skin resurfacing, with lower morbidity than the carbon dioxide laser. In a series of 625 patients who had erbium:YAG resurfacing, the following conclusions were reached. (1) Long-term (> 6 months) improvement in wrinkles and acne scars required total fluences exceeding 20 J/cm2. Periocular wrinkles required total fluences of between 20 and 40 J/cm2, depending on the depth of the wrinkles and skin thickness. Perioral rhytids required total fluences of between 40 and 80 J/cm2, whereas the cheeks and forehead required total fluences of 30 to 60 J/cm2. (2) Deeper wrinkles were best treated with a combination of erbium and carbon dioxide lasers, which minimized the bleeding that occurs with deeper erbium resurfacing. The simultaneous combined erbium with carbon dioxide laser was particularly advantageous. (3) Complications were relatively uncommon using the scanning erbium laser, and most adverse effects occurred early in the series. Scarring occurred in 5 of the 625 patients (0.8 percent) and mostly resolved with intralesional steroids. Hyperpigmentation occurred in 21 of the 625 patients (3.4 percent) and was temporary in nature. Hypopigmentation, which became evident after 6 months, occurred in 25 of the 625 patients (4.0 percent) but was mild and not a significant cosmetic problem, except in one patient who developed scarring on the neck. Hypopigmentation seemed to be related to the depth of resurfacing. Four of the 625 patients (0.6 percent) developed temporary scleral show, but no patients had permanent ectropion. Eight of the 625 (1.3 percent) developed synechiae under the lower eyelid, which required minor correction.