Direct stimulatory effect of low-intensity 670 nm laser irradiation on human endothelial cell proliferation

BACKGROUND

Endothelial cell (EC) proliferation plays a key role in the process of tissue repair. Low-intensity laser irradiation has been demonstrated to accelerate wound healing and to improve microvascularization.

OBJECTIVES

The present study evaluated a possible stimulatory influence of low-intensity laser irradiation on human umbilical vein endothelial cell (HUVEC) proliferation in a systematic manner.

METHODS

Subconfluent cultures of HUVEC were irradiated every other day with a 670-nm diode laser (intensity: 10-65 mW cm(-2), dose: 2-8 J cm(-2)) during a period of 6 days. Cell proliferation was evaluated quantitatively by counting in a haemocytometer.

RESULTS

Our data demonstrate a dose-dependent and intensity-dependent stimulatory effect of laser irradiation on HUVEC cell proliferation. Doses of between 2 and 8 J cm(-2) induced statistically significant cell proliferation. Testing different intensities at a constant dose of 8 J cm(-2), 20 and 65 mW cm(-2) induced most pronounced cell proliferation.

CONCLUSIONS

Low-intensity laser irradiation influences EC proliferation and might thereby contribute to the increase in angiogenesis and the acceleration of wound healing in vivo.

[Reciprocity regulation in photobiology. An overview]

According to the rule of Bunsen and Roscoe, a photochemical reaction is directly proportional to the total energy dose, irrespective of the time over which this dose is delivered. To date few studies have addressed the validity of this rule in experimental and applied photobiology. Most of these data point to the fact that the rule of reciprocity is invalid or of limited validity for many photobiological reactions. For UV-induced cell death, photocarcinogenesis, psoralen photochemistry, and the effects of low level laser radiation it has been shown that at a constant total dose, the intensity of the source is a major factor that determines quality and quantity of the response. In clinical photomedicine systematic investigations on the reciprocity of exposure time and radiation intensity are lacking. Such studies are urgently needed since it can be concluded from experimental evidence, that their results might lead to therapeutic regimens with an improved therapeutic index, i.e. maximized therapeutic efficacy with minimized adverse reactions.

Sex differences in HAART-associated dyslipidaemia

OBJECTIVES

Because female sex protects against dyslipidaemia and atherosclerosis in normal subjects, we aimed to reveal potential sex differences in metabolic side-effects of a newly initiated highly active antiretroviral therapy (HAART) regimen, and to relate these changes to endothelial cell activation as measured by levels of circulating E-selectin (cE-selectin).

DESIGN

Prospective longitudinal cohort study.

SETTING

Tertiary care centre at a University Hospital.

METHODS

HIV-seropositive male (n = 27) and female patients (n = 13) with a plasma viral load of > or = 10 000 copies/ml and 35 healthy controls were enrolled in the study. All participants were weight stable, free of acute opportunistic infections, and had not taken any protease inhibitors before. Serum levels of lipids, insulin, leptin, and cE-selectin were measured before initiation of HAART, and at 3 and 6 months thereafter.

RESULTS

HAART increased serum levels of triglycerides, leptin, and low-density lipoprotein (LDL) cholesterol; these effects were more distinct in women. Fasting insulin levels and the LDL : high density lipoprotein (HDL) ratio increased only in female HIV-infected patients (P < 0.02 versus men). In contrast, endothelial activation, as measured by cE-selectin, decreased more in men (P < 0.02) than in women. As a consequence, women had higher triglycerides and leptin levels after therapy than did men, and the LDL : HDL ratio and cE-selectin levels, which were initially higher in men, were no longer different between the sexes.

CONCLUSIONS

Metabolic adverse effects during HAART are more pronounced in women than in men. Hence, female HIV-infected patients seem to loose part of their natural protection from atherosclerosis during antiretroviral therapy.

Low-intensity laser therapy: a review

Low-intensity laser radiation is characterized by its ability to induce athermic, nondestructive photobiological processes. Although it has been in use for more than 30 years, this phototherapy is still not an established therapeutic modality. We have summarized the main arguments being brought up against the use of this therapy and have reviewed the literature addressing both its in vitro and in vivo effects. We conclude that low-intensity laser irradiations might be of benefit in selected indications if the existing preliminary data can be confirmed by more prospective and well-controlled studies.

Low intensity laser irradiation in the treatment of recalcitrant radiation ulcers in patients with breast cancer--long-term results of 3 cases

Radiotherapy can be followed by recalcitrant skin ulcers. As low intensity laser irradiation has been demonstrated to have a beneficial effect on impaired wound healing, we investigated its efficacy and safety in three patients with chronic radiation ulcers. The three patients, previously mastectomized due to breast cancer, with recalcitrant radiation ulcers of the skin were treated with a 30 mW helium-neon laser (wavelength: 632.8 nm, intensity: 3 mW/cm2, dose: 30 J/ cm2) three times weekly. In all patients, complete wound closure was achieved within a period of 7, 5, and 8 weeks. One patient died 6 weeks after laser treatment due to tumor cachexia. Neither of the other patients showed recurrence of radiation ulcers or neoplasm during a follow-up of 36 months. Low intensity helium-neon laser irradiation has been shown to be effective in the induction of wound healing in radiotherapy-induced ulcers in three patients with breast cancer.

Beneficial effects of protease inhibitors on body composition and energy expenditure: a comparison between HIV-infected and AIDS patients

OBJECTIVES

(i) To investigate whether protease inhibitor (PI) (nelfinavir)-containing highly active antiretroviral therapy (HAART) affects body composition differently in HIV-infected and AIDS patients without wasting syndrome. (ii) To delineate the changes in resting energy expenditure (REE) under PI therapy, and to determine whether sustained reductions in HIV RNA would decrease REE.

DESIGN

Prospective longitudinal cohort study with individually matched healthy controls.

SETTING

Tertiary care centre at a University Hospital.

METHODS

HIV-seropositive (n = 20) and AIDS patients (n = 17) with a plasma viral load of at least 10000 copies/ml and 37 healthy volunteers were enrolled. All participants were weight stable, free of acute opportunistic infections, and naive to PI therapy. Patients underwent testing of bioelectrical impedance analysis (BIA), indirect calorimetry and food intake, shortly before the initiation of HAART and 24 weeks thereafter.

RESULTS

Both patient groups gained weight, body mass index (BMI), and fat-free mass (FFM) (P < 0.05 versus baseline), whereas only AIDS patients gained fat mass. Increases were more pronounced in the AIDS group. REE was elevated compared with corresponding controls at baseline, and decreased similarly in HIV and in AIDS patients during PI therapy (P < 0.05). The reduction in the viral burden preceded the decrease in REE by several weeks.

CONCLUSION

Body composition and metabolic parameters improved during PI therapy in HIV-infected and AIDS patients without wasting. Although an early reduction in viral load as a result of HAART does not seem to influence REE directly, sustained viral load suppression may promote a decrease in energy expenditure.

Low-intensity laser therapy is an effective treatment for recurrent herpes simplex infection. Results from a randomized double-blind placebo-controlled study

Recurrent infection with herpes simplex virus is a common disease. Recently, alternative therapies have been introduced. Among those, low-intensity laser therapy mainly used for the acceleration of wound healing and in pain therapy has previously been shown to be of benefit in herpes zoster infections. In this study we evaluated the influence of low-intensity laser therapy (wavelength 690 nm, intensity: 80 mW per cm2, dose: 48 J per cm2) in 50 patients with recurrent perioral herpes simplex infection (at least once per month for more than 6 mo) in a randomized, double-blind placebo-controlled trial design. Patients in the laser group received daily irradiations for 2 wk, whereas patients in the placebo group were sham-irradiated. After completion of the laser/sham treatment, patients were asked to return to the Department of Dermatology, University of Vienna Medical School at the time of recurrence. All except two patients completed the study and were monitored for 52 wk. The median recurrence-free interval in the laser-treated group was 37.5 wk (range: 2-52 wk) and in the placebo group 3 wk (range: 1-20 wk). This difference was found to be statistically significant (p < 0.0001; Wilcoxon's Rank Sum Test). In conclusion, we demonstrated that a total of 10 irradiations with low-intensity laser therapy significantly lowers the incidence of local recurrence of herpes simplex infection. Since this athermic phototherapeutic modality represents a safe, noninvasive treatment, it might be considered as an alternative to established therapeutic regimens in this indication.

Diabetic neuropathic foot ulcer: successful treatment by low-intensity laser therapy

OBJECTIVE

To evaluate the efficacy of low-intensity laser irradiation for the induction of wound healing of a diabetic neuropathic foot ulcer.

CASE

We report a case of a man with insulin-dependent diabetes mellitus, sensory neuropathy, macroangiopathy and microangiopathy who had been suffering from an ulcer of his first left toe accompanied by osteomyelitis for 6 weeks.

RESULTS

After a total of 16 sessions of low-intensity laser therapy using a 670-nm diode laser administered within a 4-week period the ulcer healed completely. During a follow-up period of 9 months, there was no recurrence of the ulcer even though the patient's metabolic condition remained unstable.

CONCLUSIONS

Although laser therapy was not applied as a monotherapy, the present observation suggests that it might constitute a useful side-effect-free alternative treatment modality for the induction of wound healing of neuropathic ulcers in diabetic patients. Therefore large properly controlled randomized studies seem justified.

Role of ground and excited singlet state oxygen in the red light-induced stimulation of Escherichia coli cell growth

Irradiation of selected Escherichia coli defective strains with red-light induces a stimulation of the cell growth rate. Such effect is wavelength-dependent and is accompanied by a transient increase of the cell volume and some enzymic activities. The presence of oxygen appears to be essential for the occurrence of a significant photostimulatory effect. The results obtained upon irradiation in the presence of quenchers (tryptophan, histidine, azide) or enhancers (deuterium oxide) of singlet oxygen (1O2) strongly suggest that this activated oxygen derivative is generated by excitation of endocellular chromophores (possibly cytochromes). The reaction of 1O2 with nearby cellular targets could induce a sublethal cell damage which in turn promotes an accelerated cell metabolism.

Increased dermal angiogenesis after low-intensity laser therapy for a chronic radiation ulcer determined by a video measuring system

Acute and chronic radiation-induced dermatitis can occur after high doses of ionizing radiation of the skin. We describe a patient with a long-lasting radiotherapy-induced ulcer that healed after low-intensity laser therapy. A video measuring system was used to determine the number of dermal vessels in the ulcer before and after laser treatment. We found a statistically significant increase in the number of dermal vessels after low-intensity laser therapy in both the central and marginal parts of the ulcer compared with its pretreatment status.

Induction of complete wound healing in recalcitrant ulcers by low-intensity laser irradiation depends on ulcer cause and size

Chronic skin ulcers still represent a therapeutic challenge in dermatology. Among the various non-invasive treatment modalities used for the improvement of impaired wound healing, low-intensity laser irradiations are gaining an increasing body of interest. We used low-intensity laser irradiations delivered by a 30 mW helium-neon laser at an energy density of 30 J/cm2 three times weekly for the induction of wound healing in ulcers of diverse causes. Twenty patients with the same number of ulcers, which had previously been treated by conventional wound care for a median period of 34 weeks (range: 3-120 weeks) without any significant evidence of healing, were included in the study. Concerning the underlying disorders, patients were divided into four groups: diabetes, arterial insufficiency, radio damage and autoimmune vasculitis. In all ulcers, complete epithelization could be induced by laser therapy. No amputation or any other surgical intervention was necessary and no adverse effects of any kind were noted during low-intensity laser treatment. Regarding the different diagnoses, a statistically significant difference was noted (P = 0.008): ulcers due to radio damage healed significantly faster than those caused by diabetes (6 weeks [range: 3-10 weeks] vs. 16 weeks [range: 9-45 weeks], P = 0.005). Wound healing in autoimmune vasculitis (24 weeks [range: 20-35 weeks]) required longer than in radiodermitis, although the difference was not significant. In addition to the diagnosis, wound size was found to be an important factor influencing the duration of wound closure (P = 0.028), whereas duration of previous conventional treatment (P = 0.24) and depth (P = 0.14) showed no effect. Our results indicate that low-intensity laser irradiation could be a valuable non-invasive tool for the induction of wound healing in recalcitrant ulcers, and that healing time is correlated with the ulcer cause and size.

Healing of Bone Affections and Gangrene with Low-Intensity Laser Irradiation in Diabetic Patients Suffering from Foot Infections

OBJECTIVE: Evalution of low-intensity laser irradiation on the healing of bone affections and gangrene in patients suffering from diabetic microangiopathy. DESIGN: Case-report study. PATIENTS: Two consecutive diabetic male patients with gangrene, osteomyelitis, and bone fractures. INTERVENTION: Helium-neon laser irradiation (36 J/cm2 ) 50 min/day. MAIN OUTCOME PARAMETER: Healing of gangrene and corticalis lesion as well as remineralisation of bone affections. RESULTS: Within a mean period of 14 weeks not only a complete healing of the diabetic gangrenes but also a radiographically determined reestablishment of corticalis and remineralisation of preexisting bone affections could be achieved. CONCLUSION: We therefore conclude that low-intensity laser irradiation should be further tested as an additional beneficial therapeutic modality for the healing of gangrene and bone affections in diabetic patients.

Flow cytometric quantification of UV-induced cell death in a human squamous cell carcinoma-derived cell line: dose and kinetic studies

Exposure to ultraviolet (UV) radiation and photochemotherapy induces apoptotic cell death in epidermal cells. In this study annexin V binding and propidium iodide (PI) uptake have been measured by flow cytometry to evaluate UV-induced cell death in the human squamous cell carcinoma-derived cell line A 431. Physiological and therapeutical relevant doses of UVA, UVA1, UVB, narrow-band UVB (311 nm) and photochemotherapy using 100 ng/ml of 8-methoxypsoralen (8-MOP) with UVA or UVA1 (PUVA or PUVA1) have been applied. Doses ranged from 8 to 96 J/cm2 for UVA1 and UVA, from 8 to 128 mJ/cm2 for UVB, from 256 to 4096 mJ/cm2 for narrow-band UVB (311 nm) and from 1 to 16J/cm2 for photochemotherapy. Results show that the amount of annexin V binding, a measure of early apoptosis, as well as PI uptake, a parameter of ultimate cell death, are strictly correlated with the applied UV dose. Peak values of annexin V-positive cells are noted 12 h after UV exposure in all protocols and are followed by an increase of PI-uptaking cells with peak values at 24 h after UVA and UVA1, and 48 h after PUVA, PUVA1, UVB and narrow-band UVB. To compare the effect of different wavelengths and light sources, dose equivalents are calculated based on the induction of 50% cell death (as determined by PI uptake). The equivalents are 96 J/cm2 for UVA and UVA1, 16 J/cm2 for PUVA and PUVA1, 256 mJ/cm2 for UVB and 2048 mJ/cm2 for narrow-band UVB. Our results establish annexin V/PI double staining as an appropriate method for the quantification of UV-induced cell death. Moreover, they provide a basis for further investigations concerning mechanisms and modifications of UV-induced apoptosis.

Low-intensity laser irradiation improves skin circulation in patients with diabetic microangiopathy

OBJECTIVE

Diabetic foot problems due to angiopathy and neuropathy account for 50% of all nontraumatic amputations and constitute a significant economic burden to society. Low-intensity laser irradiation has been shown to induce wound healing in conditions of reduced microcirculation. We investigated the influence of low-intensity laser irradiation by means of infrared thermography on skin blood circulation in diabetic patients with diabetic microangiopathy.

RESEARCH DESIGN AND METHODS

Thirty consecutive patients with diabetic ulcers or gangrenes and elevated levels of glycosylated hemoglobin were randomized by blocks of two to receive either a single low-intensity laser irradiation with an energy density of 30 J/cm2 or a sham irradiation over both forefoot regions in a double-blind placebo-controlled clinical study. Skin blood circulation as indicated by temperature recordings over the forefoot region was detected by infrared thermography.

RESULTS

After a single transcutaneous low-intensity laser irradiation, a statistically significant rise in skin temperature was noted (P < 0.001 by ANOVA for repeated measurements), whereas in the sham-irradiated control group, a slight but significant drop in temperature (P < 0.001) was found. Subsequently performed contrasts for comparison of measurements before and after irradiation revealed significant temperature increases at 20 min of irradiation time (P < 0.001), at the end of the irradiation (P < 0.001), and 15 min after stopping the irradiation (P < 0.001). In the sham-irradiated feet, the drop in local skin temperature was not significant at 20 min (P = 0.1), but reached significance at the end of the sham-irradiation procedure (P < 0.001) and 15 min after the end of sham irradiation (P < 0.001).

CONCLUSIONS

The data from this first randomized double-blind placebo-controlled clinical trial demonstrate an increase in skin microcirculation due to athermic laser irradiation in patients with diabetic microangiopathy.

Effects of low power laser-irradiation on differential blood count and body temperature in endotoxin-preimmunized rabbits

Low power laser irradiation has been shown to have various immune-modulatory effects under in vitro conditions but little is known about such effects in animal models. Escherichia coli endotoxin-preimmunized rabbits were used to determine the influence of transcutaneously applied low power laser light on differential blood count and rectal temperature. After three initial immunizations animals were either boostered with 5 ng/kg of endotoxin or injected with pyrogen-free saline and subsequently underwent irradiation using two different wavelengths of red laser light and sham irradiation, respectively. Differential blood count of laser-treated animals was characterized by significantly higher lymphocyte values and lower neutrophil values at twenty hours (boostered rabbits) and twenty-three hours (non-boostered rabbits) after irradiation. Differential blood cell counts returned to baseline values within 23 hours in the boostered animals, whereas in the non-boostered rabbits lymphocytes showed a trend to further increase. Recording of rectal temperature revealed a further rise after laser application, changes being of greater magnitude and longer duration in the non-boostered animals. These results seem to indicate that a single low power laser irradiation can modulate immune-responses depending on the immunological status of the organism.