Inhibitory effects of low-level laser therapy on skin-flap survival in a rat model

BACKGROUND:Although several studies have demonstrated the effects of low-level laser therapy (LLLT) on skin flap viability, the role of higher doses has been poorly investigated.OBJECTIVE:To investigate the inhibitory effect of the LLLT (λ=670 nm) on the viability of random skin flaps in a rat model using an irradiation energy of 2.79 J at each point.METHODS:Sixteen Wistar rats were randomly assigned into two groups: sham laser irradiation (n=8); and active laser irradiation (n=8). Animals in the active laser irradiation group were irradiated with a 670 nm diode laser with an energy of 2.79 J/point, a power output 30 mW, a beam area of 0.028 cm², an energy density of 100 J/cm², an irradiance of 1.07 W/cm² for 93 s/point. Irradiation was performed in 12 points in the cranial skin flap portion. The total energy irradiated on the tissue was 33.48 J. The necrotic area was evaluated on postoperative day 7.RESULTS:The sham laser irradiation group presented a mean (± SD) necrotic area of 47.96±3.81%, whereas the active laser irradiation group presented 62.24±7.28%. There was a significant difference in skin-flap necrosis areas between groups (P=0.0002).CONCLUSION:LLLT (λ=670 nm) increased the necrotic area of random skin flaps in rats when irradiated with an energy of 2.79 J (100 J/cm²).     

Effects of low-power diode lasers on flap survival

We investigated the effect of low-power laser irradiation on the survival of experimental skin flaps in rats. A gallium-aluminum-arsenide diode laser that was developed by the Japan Medical Laser Laboratory was used. The laser power was 15 mW and the wavelength 830 nm. Irradiation was carried out, either before or after flap elevation, in two groups of 20 Wistar strain rats. A third group of 20 rats served as controls. A caudally based skin flap, 3 X 9 cm, was designed on the back of each rat. Laser irradiation therapy was performed for 5 consecutive days for 6 minutes per flap per day, preoperatively in one group and postoperatively in the other. Seven days postoperatively, the survival areas of the flaps were measured and compared. The survival area was increased significantly in both groups receiving laser therapy, probably due to the observed proliferation of blood vessels around the irradiated points and an increase in blood flow.     

Helium-neon laser in viability of random skin flap in rats

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine the role of helium-neon (He-Ne) laser random skin flap viability in rats. STUDY DESIGN/MATERIALS AND METHODS: Experimentally controlled randomized study. Forty-eight Wistar-EPM rats were used, weighed, and divided into 4 groups with 12 rats each. The random skin flap was performed measuring 10 x 4 cm, with a plastic sheet interposed between the flap and the donor site. The Group 1 (control) underwent sham irradiation with He-Ne laser. The Group 2 was submitted to laser irradiation, using the punctual contact technique on the skin flap surface. The Group 3 was submitted to laser irradiation surrounding the skin flap, and the Group 4 was submitted to laser irradiation both on the skin flap surface and around it. The experimental groups were submitted to He-Ne laser irradiation with 3 J/cm(2) energy density immediately after the surgery and for the four subsequent days. The percentage of necrotic area of the four groups was calculated at the 7th post-operative day, through a paper-template method. RESULTS: Group 1 reached an average necrotic area of 48.86%; Group 2, 38.67%; Group 3, 35.34%; and Group 4, 22.61%. After the statistic analysis, results showed that all experimental groups reached statistically significant values when compared to the control group, and Group 4 was the best one, when compared to all groups of this study (P<0.001). CONCLUSION: The He-Ne laser irradiation was efficient to increase random skin flap viability in rats.     

Low-level laser irradiation,cyclooxygenase-2 (COX-2) expression and necrosis of random skin flaps in rats

Skin flaps are still a matter of concern among surgeons, as failures can occur leading to flap necrosis. However, low-level laser irradiation has been reported as an effective tool to improve the viability of ischemic flaps, yet its mechanisms of action remain unclear. We investigated the effect of low-level laser irradiation on the viability of random skin flaps in rats and determined COX-2 expression in the flap pedicle. The study animals comprised 24 EPM-1 Wistar rats which were randomly allocated into three equal groups. A cranially based dorsal random skin flap measuring 10 × 4 cm was created in all the animals. In one group, laser irradiation was simulated (sham group), and in the other two groups the animals were irradiated at 12 points with 0.29 J at 20 mW (energy density 10.36 J/cm², irradiance 0.71 W/cm²), or with 7.3 J at 100 mW (energy density 260.7 J/cm², irradiance 3.57 W/cm²). These procedures were applied to the cranial half of the flap immediately after surgery and were repeated on days 2 and 5 after surgery. The percentage necrotic area was determined on day 7 after surgery by the paper template method. The immunohistochemical expression of COX-2 in the samples was given scores from 0 to 3. The necrotic area was smaller in group irradiated at 7.3 J compared to sham-treated group and to the group irradiated at 0.29 J (P < 0.05); there was no difference between the sham-treated group and group irradiated at 0.29 J. COX-2 expression was lower in the group irradiated at 7.3 J than in the sham-treated group and the group irradiated at 0.29 J (P < 0.001). Low-level laser therapy was effective in decreasing random skin flap necrosis in rats using a laser energy of 7.30 J per point. Laser irradiation also decreased the expression of COX-2 in the flap pedicle.     

Efficacy of postoperative steroids on ischemic skin flap survival in rats

Necrosis of skin flaps remains a significant clinical problem. This study examined whether steroids improve skin flap survival in rats. Random skin flaps were raised in 30 male Sprague-Dawley rats. Intramuscular methylprednisolone (n=15) or saline solution (n=15) were administered 1, 24, and 48 h after flap elevation. Surviving flap areas were measured after 7 days. The mean surviving flap area in the methylprednisolone group was greater than that in controls (916 vs. 675 mm). These results suggest that postoperative methylprednisolone improves skin flap viability in the ischemic rat flap model.     

Increased Survival of Experimental Skin Flaps in Rats Following Treatment with Antiadrenergic Drugs

The effect upon the survival of skin flaps of several drugs which affect the adrenergic system was studied in rats. In control animals 41% of the skin flaps had survived seven days after the operation. Reserpine (1 mg/kg) injected intraperioneally (i.p.) three days and one day before the flap operation increased the surviving flap area by 75% (p<0.001) as compared to control rats injected with saline. I.p. injection of guanethidine (5 mg/kg) or bretylium (10 mg/kg) every 12 hours, starting 24 hours before surgery and continued for 5 consecutive days, also increased the surviving flap area (19 and 33% respectively p<0.001). The surviving flap area was unchanged when desipramine (5 mg/kg) was injected in the same way and was decreased by 15% (p<0.05) following i.p. injection of the MAO inhibitor pheniprazine (5 mg/kg). Treatment with α-methyl-p-tyrosine (75 mg/kg), i.p. 30 min before surgery or 6-hydroxydopamine (50 mg/kg) i.v. 24 hours prior to surgery also increased the flap survival (56 and 49% increase in surviving flap area, respectively, p<0.001). The results demonstrated that the survival of skin flaps increased when the function of the adrenergic nervous system was inhibited. Enhanced sympathetic nervous activity slightly reduced or did not affect skin flap survival.     

Neutrophil function and pO2 in irradiated skin- and skin-muscle-flaps

Results of earlier investigations have demonstrated impaired function of polymorph-nuclear cells (PMN) in previously irradiated tissue. This study was designed to examine the effect of local oxygen pressure (pO₂) on neutrophil function in irradiated tissue. By choosing a pig model of irradiated and non-irradiated high perfusion wound environment (i.e. musculo-cutaneous (MC) flap) vs. a poor perfusion wound environment (i.e. random pattern (RP) skin flap), the effect of different pO₂ levels on neutrophil phagocytosis and respiratory burst (H₂O₂ production) were measured at 6, 12, and 16 weeks after irradiation. In both kinds of irradiated flaps, pO₂ levels and neutrophil function were significantly lower (RP: <20 mmHg; MC: 30 mmHg) than in corresponding flaps from non-irradiated tissue (RP: 26–28 mmHg; MC: 30–40 mmHg) and showed a progressive decline with increasing time interval after irradiation. Correlation between pO₂ and phagocytosis (p=0.001) and H₂O₂ production (p=0.02) proved to be statistically significant for the irradiated random pattern flaps, but not for musculocutaneous flaps.     

The influence of helium-neon laser irradiation on the viability of skin flaps in the rat.

Low energy helium-neon (He-Ne) laser irradiation has been shown to induce various therapeutic effects. We investigated its effect on the viability of skin flaps in the rat. Thirty rats underwent skin flap elevation and were then divided into three equal groups. Group I (control) was not irradiated. Groups II and III were irradiated for 5 days postoperatively, Group II to the transition zone (between the live and expected necrotic areas) and Group III to the transitional and distal zones; total energy, 2.9 J/cm(2)for each rat. Ten days after the last treatment larger surviving areas were demonstrated macroscopically in Groups II and III (P< 0.01 and 0.001, respectively). Histological examination showed tremendous proliferation of capillaries (P相似文献   

LED (660 nm) and laser (670 nm) use on skin flap viability: angiogenesis and mast cells on transition line

Skin flap procedures are commonly used in plastic surgery. Failures can follow, leading to the necrosis of the flap. Therefore, many studies use LLLT to improve flap viability. Currently, the LED has been introduced as an alternative to LLLT. The objective of this study was to evaluate the effect of LLLT and LED on the viability of random skin flaps in rats. Forty-eight rats were divided into four groups, and a random skin flap (10?×?4 cm) was performed in all animals. Group 1 was the sham group; group 2 was submitted to LLLT 660 nm, 0.14 J; group 3 with LED 630 nm, 2.49 J, and group 4 with LLLT 660 nm, with 2.49 J. Irradiation was applied after surgery and repeated on the four subsequent days. On the 7th postoperative day, the percentage of flap necrosis was calculated and skin samples were collected from the viable area and from the transition line of the flap to evaluate blood vessels and mast cells. The percentage of necrosis was significantly lower in groups 3 and 4 compared to groups 1 and 2. Concerning blood vessels and mast cell numbers, only the animals in group 3 showed significant increase compared to group 1 in the skin sample of the transition line. LED and LLLT with the same total energies were effective in increasing viability of random skin flaps. LED was more effective in increasing the number of mast cells and blood vessels in the transition line of random skin flaps.     

Adenovirus-mediated transforming growth factor-beta ameliorates ischemic necrosis of epigastric skin flaps in a rat model

BACKGROUND: Gene therapy has been recently introduced as a novel approach to treat ischemic tissues by using the angiogenic potential of certain growth factors. We investigated the effect of adenovirus-mediated gene therapy with transforming growth factor-beta (TGF-beta) delivered into the subdermal space to treat ischemically challenged epigastric skin flaps in a rat model. MATERIAL AND METHODS: A pilot study was conducted in a group of 5 animals pretreated with Ad-GFP and expression of green fluorescent protein in the skin flap sections was demonstrated under fluorescence microscopy at 2, 4, and 7 days after the treatment, indicating a successful transfection of the skin flaps following subdermal gene therapy. Next, 30 male Sprague Dawley rats were divided into 3 groups of 10 rats each. An epigastric skin flap model, based solely on the right inferior epigastric vessels, was used as the model in this study. Rats received subdermal injections of adenovirus encoding TGF-beta (Ad-TGF-beta) or green fluorescent protein (Ad-GFP) as treatment control. The third group (n = 10) received saline and served as a control group. A flap measuring 8 x 8 cm was outlined on the abdominal skin extending from the xiphoid process proximally and the pubic region distally, to the anterior axillary lines bilaterally. Just prior to flap elevation, the injections were given subdermally in the left upper corner of the flap. The flap was then sutured back to its bed. Flap viability was evaluated seven days after the initial operation. Digital images of the epigastric flaps were taken and areas of necrotic zones relative to total flap surface area were measured and expressed as percentages by using a software program. RESULTS: There was a significant increase in mean percent surviving area between the Ad-TGF-beta group and the two other control groups (P < 0.05). (Ad-TGF-beta: 90.3 +/- 4.0% versus Ad-GFP: 82.2 +/- 8.7% and saline group: 82.6 +/- 4.3%.) CONCLUSIONS: In this study, the authors were able to demonstrate that adenovirus-mediated gene therapy using TGF-beta ameliorated ischemic necrosis in an epigastric skin flap model, as confirmed by significant reduction in the necrotic zones of the flap. The results of this study raise the possibility of using adenovirus-mediated TGF-beta gene therapy to promote perfusion in random portion of skin flaps, especially in high-risk patients.     

低能量氦-氖激光血管内照射治疗皮肤撕脱伤疗效观察

目的 探讨低能量氦（Ｈｅ）－氖（Ｎｅ）激光血管内照射对撕脱皮瓣原位回植术后皮瓣成活的影响,方法 选择伤后６小时内行清创、撕脱瓣原位回植术撕脱伤患者５８例,其中治疗组３１例应用能量Ｈｅ－Ｎｅ激光血管内照射加常规治疗;对照组２７例仅用常规治疗。结果 术后１５天治疗组撕脱瓣的成活面积、成活质量均明显优于对照组（Ｐ〈０．０５）,治疗组血液流变学参数变化在术后５天内最明显。结论 低能量Ｈｅ－Ｎｅ激光血管内照     

Evaluation of clinically applicable exsanguination treatments to alleviate venous congestion in an animal skin flap model

This study compares the effectiveness of alleviating venous congestion with mechanically-made outlets or leech therapy in promoting skin flap survival. Free flaps of abdominal skin (3 x 6 cm) were raised on Sprague-Dawley rats and subjected to ischemic events, simulating venous congestion. Animals received 1) no treatment; 2) two treatments involving two 18-gauge needle-puncture outlets; or 3) two sessions of leech therapy. Flap perfusion was monitored with a scanning laser Doppler flowmeter. Photographic images of flaps at 7 days were assessed for areas of normal tissue (n = 15), and laser Doppler flowmeter data consisted of control (n = 6), outlet (n = 6), and leech (n = 7). Both the needle-puncture outlet (40.0% +/- 9.24%) and leech treated (34.6% +/- 7.34%) groups had a significantly greater surviving skin area than untreated control flaps (8.0% +/- 5.0%), with 2 of 15 flaps receiving mechanical outlets exhibiting > 90% surviving area. After 7 days, laser Doppler flowmeter data showed greater mean perfusion in the outlet (71.7% +/- 16.8%) and leech (92.6% +/- 17.2%) treated groups, compared to controls (15.2% +/- 10.2%). There was a significant increase in perfusion in the outlet (13.3% +/- 6.2%) and leech (9.1% +/- 1.1%) treated groups from the end of secondary ischemia to day 7 (p < 0.05) compared to controls. The results suggest that two spatially separated outlets are as effective as one leech in increasing the area of surviving skin in venous congested flaps.     

Effects of 830 and 670 nm Laser on Viability of Random Skin Flap in Rats

Abstract Objective: This study aimed to investigate the effect of 830 and 670?nm diode laser on the viability of random skin flaps in rats. Background data: Low-level laser therapy (LLLT) has been reported to be successful in stimulating the formation of new blood vessels and reducing the inflammatory process after injury. However, the efficiency of such treatment remains uncertain, and there is also some controversy regarding the efficacy of different wavelengths currently on the market. Materials and methods: Thirty Wistar rats were used and divided into three groups, with 10 rats in each. A random skin flap was raised on the dorsum of each animal. Group 1 was the control group, group 2 received 830?nm laser radiations, and group 3 was submitted to 670?nm laser radiation (power density=0.5 mW/cm(2)). The animals underwent laser therapy with 36?J/cm(2) energy density (total energy=2.52?J and 72?sec per session) immediately after surgery and on the 4 subsequent days. The application site of laser radiation was one point at 2.5?cm from the flap's cranial base. The percentage of skin flap necrosis area was calculated on the 7th postoperative day using the paper template method. A skin sample was collected immediately after to determine the vascular endothelial growth factor (VEGF) expression and the epidermal cell proliferation index (KiD67). Results: Statistically significant differences were found among the percentages of necrosis, with higher values observed in group 1 compared with groups 2 and 3. No statistically significant differences were found among these groups using the paper template method. Group 3 presented the highest mean number of blood vessels expressing VEGF and of cells in the proliferative phase when compared with groups 1 and 2. Conclusions: LLLT was effective in increasing random skin flap viability in rats. The 670?nm laser presented more satisfactory results than the 830?nm laser.     

Experimental model for the evaluation of topical application of a solution to help myocutaneous flap transposition

The aim of this article is the evaluation of the topical application of a solution of hydrogen peroxide (H2O2) 8% and dimethyl sulphoxide (DMSO) 50% in order to reduce ischaemic failure in random skin flaps. This study was performed using a rabbit model. Two parallel, cephalad-based para-midline random cutaneous flap (10 cm x 2.5 cm) were elevated and resutured in place on the dorsum of 40 New Zealand rabbits. The 80 flaps thus obtained were then randomly divided into one control group and three experimental groups of 20 flaps each. Flaps from the control group (group A) were topically treated with saline, while flaps from experimental group B were treated with H2O2 8%, flaps from experimental group C with DMSO 50%, and flaps from experimental group D with a solution of 50% DMSO + 8% H2O2. Each solution was topically applied, 20 cc per three times a day, on the flaps for seven days, starting on the immediate postoperative period. Transcutaneous oxygen tension (Ptc O2) measurements were carried out in all flaps, 72 h after flap elevation. The percentage of surviving skin area of each flap was determined by planimetry 7 days after flap elevation. The mean surviving area of the group A (control) flaps was 71%. The mean surviving area of the group B (H2O2-treated) flaps was 72%. The mean surviving area of the group C (DMSO-treated) flaps was 76%, and that of the group D (DMSO + H2O2-treated) flaps was 92%. While no statistically significant differences were found between the survival rates of both the flaps treated with H2O2 or DMSO alone and that of the control group, the mean surviving rate of the DMSO + H2O2 treated flaps (+20%) was statistically higher than that of the control flaps. Similarly, a statistically significant difference has been found between the mean Ptc O2 values of the DMSO + H2O2 flaps and those of the other three groups of flaps.     

Dipyrone Increases the Blood Flow of Arterial Dorsal Skin Flaps

Background  Findings have shown that dipyrone has a beneficial effect on skin flap survival. A pharmacologic explanation for this effect points to its vascular smooth muscle-relaxing effect. This study evaluated the effect of dipyrone on blood flow and thus survival of rat random dorsal skin flaps. Methods  For this study, 27 male Wistar albino rats were randomly assigned to control (treated with sterile saline) and treatment (treated with dipyrone 100 mg/kg) groups. A random dorsal skin flap measuring 4 × 10 cm was raised in each animal. The edges of the flap were sutured back into their original place. Dipyrone treatment continued at 100 mg/kg per day during the 7-day observation period. Blood flow was recorded by laser Doppler preoperatively (baseline), immediately after the flap was sutured back to its original position (acute), and on postoperative day 7. The degree of necrosis was evaluated by the grid method on day 7. Mean percentage necrosis and minimum laser Doppler readings were compared between the two groups. Results  A significant increase in blood flow was observed in the dipyrone group at the acute phase but not on postoperative day 7. The percentage of the necrotic area was lower in the treatment group. However, it did not reach the significance level (p = 0.09). Conclusion  Dipyrone significantly decreases skin blood flow at the acute phase of flap elevation although the necrotic area does not reach the significance level. An erratum to this article can be found at     

Effects of insulin-dependent diabetes mellitus on perforator-based flaps in streptozotocin diabetic rats

The purpose of this study was to investigate the effects of insulin-dependent diabetes mellitus (IDDM) on the viability of perforator-based flaps (pbf) in diabetic rats. Random-pattern flaps were also used as a control flap group. Wistar Albino rats, female, n = 60, were used. The study was done with four groups: Group 1 (diabetic rats, pbf), Group 2 (non-diabetic rats, pbf), Group 3 (diabetic rats, McFarlane flap), and Group 4 (non-diabetic rats, McFarlane flap). Streptozocin (STZ, 55 mg/kg) in a vehicle (sodium citrate, pH 4.5) was injected into the rats intraperitonally to create an IDDM model in the diabetic groups. Only the vehicle without STZ was injected into the rats intraperitonally in the non-diabetic groups. All flaps were elevated 10 weeks after injections. Measurements of the surviving areas of the flaps, and microangiographic and histopathologic studies were done 7 days after flap elevation. Blood glucose levels of the diabetic rats were significantly higher than those of the non-diabetic groups ( p < 0.001). The surviving flap areas were 41 +/- 21 percent in Group 1, 65 +/- 25 percent in Group 2, 49 +/- 10 percent in Group 3, and 66 +/- 10 percent in Group 4. The surviving flap areas of the diabetic groups were significantly less than those of the non-diabetic groups ( p < 0.001). Specific histopathologic changes of IDDM were seen only in the diabetic groups. Microangiographies in the diabetic and non-diabetic groups were very similar. The surviving flap areas of the perforator-based and random-pattern skin flaps in the diabetic rats were decreased by IDDM. If a flap is planned for diabetic wounds, it should be kept in mind that the area of flap necrosis may be larger than those of non-diabetics.     

Nonsurgical delay of cutaneous flaps using the flashlamp pumped pulsed dye laser

The surgical delay procedure is an effective method for improving skin flap survival. However, it has many disadvantages, such as bleeding, infection, and pain. It also requires an additional operation and a long time for wound management. Nonsurgical delay has a great importance, but pharmacological efforts for delay phenomena have never found clinical application. In this study, the authors attempted to reproduce the delay phenomena via the flashlamp pumped dye laser. Forty Sprague-Dawley rats were studied in four groups of 10 rats each. The experimental and control flaps were on the same rat. Flaps were planned on the ventral skin of the rats, and were symmetrical, three sided, based caudally, and were 2 cm in width, extended to the measured midpoint between the xiphoid and the sternal notch. The laser was applied to the different areas of the experimental flaps 15 days before flap elevation. A week later flap survival was determined by overlaying millimeter-grid acetate paper. Full-surface and perimeter "lased" experimental flaps showed a marked increase in surviving areas when compared with the control flaps. This kind of flap delay has a great potential in clinic application.     

Evaluation of Role of Arterialization of Venous Flaps in Abdomen in Rats

Introduction  Reconstruction forms the primary tenet in plastic surgery. Venous flaps are a known option but the survival is limited. Arterialization of venous flap can enhance its survival. While various techniques of arterialization of venous flaps are described, there are very few studies comparing them. Material and methods  The current study was conducted among 34 rats weighing 160 to 200 grams. The rats were divided into four groups. Group I—islanded epigastric flap was raised with superficial caudal epigastric vessels as pedicle. Group II—arterialized flow through venous flap was raised with superficial caudal epigastric vein (SCEV) as afferent and lateral thoracic vein as drainage vein. Side-to-side anastomosis was done between femoral artery and vein, lateral to the origin of superficial caudal epigastric artery. Group III—after raising the flap, as in group II, femoral vein was ligated proximal to superficial caudal epigastric vessels. Group IV—an arterialized flow through venous flap was raised with superficial caudal epigastric vein as afferent and lateral thoracic vein as drainage vein. End-to-side anastomosis was done between femoral artery and superficial caudal epigastric vein. Animals that died before completion of the study were excluded. The color changes of flaps were noted. Flap survival was expressed as a percentage of the total flap surface area. The patency of anastomosis was seen on postoperative day 5. Results  There was no total flap failure. On statical analysis, the flap survival area on day 5 between Group I and Group IV was not significant ( p value 0.431). The survival area in Group I (78.85 ± 10.54%) was comparable to Group IV (65.71 ± 20.70%). Group II and III had poor results as compared with Group I. In four rats, thrombosis of arteriovenous anastomosis was noted with flap survival area of 30 to 33%. Conclusion  It was noted that epigastric venous flaps with end-to-side anastomosis between femoral artery and superficial caudal epigastric vein (group IV) have survival area comparable to islanded flaps.     

Influence of recipient-bed isolation on survival rates of skin-flap transfer in rats.

The effect of recipient-bed isolation with artificial barriers on skin-flap survival, compared to flap transfer without bed isolation, was evaluated in a modified rat epigastric skin-flap model. The pattern of blood flow in the raised flap with a proximal axial portion and distal random portion was confirmed by laser Doppler flowmetry. Forty rats were divided into four groups. Three of the groups had one of three different artificial barriers-silicone, polypropylene, or gelatin sponge. In each of these three groups, one of the artificial barriers was placed between the flap and its recipient bed after flap replacement. The flaps without bed isolation (Group 4) were used as controls. The survival area was measured 7 days postoperatively. Results demonstrated that necrosis in the groups with silicone and polypropylene barriers was significantly higher than in the controls. Histologically, neovascularization was shown in the flaps without artificial barriers. Foreign-body reactions were observed in the flaps with bed isolation and among these, severe inflammation and congestion were seen in the flaps with polypropylene isolation. In this study, the authors demonstrated that the random portion of a rat skin flap could survive partially through imbibition of plasma and the ingrowth of new vessels from the recipient bed. This neovascularization can be prevented by recipient-bed isolation with an artificial barrier. Bed isolation with a silicone sheet is suggested for use in the study of rat skin-flap survival.     

Effects of the helium-neon laser on rat kidney epithelial cells in culture

The cellular mechanisms of action of low power lasers are only partially understood. Therefore, we have studied effects of helium-neon (He−Ne) laser irradiation in a cell culture model. The studies were performed with the permanent rat kidney cell line RK-L. By electron microscopy, significant ultrastructural changes of the cells were seen after He−Ne irradiation at 40 mW/cm² for 4h (569 J/cm²), including detritus-like formations of the cell organelles close to the nucleus. While such changes were not observed after 1 h irradiation (142 J/cm²), the number of cells in mitosis increased under this condition. In addition, the rate of incorporation of³H-thymidine into DNA decreased transiently 6–9 h after 1 h He−Ne irradiation of the cells. The consumption of glucose was also lowered for 10 h after irradiation, while the production of lactate increased. Finally, the synthesis of prostaglandin E₂ was reduced following irradiation. These results show that the He−Ne laser induces significant effects at the cellular level. In addition, our findings support the concept that the biological effects of low power laser treatment involve changes in the cell cycle.