Interaction of amphiphilic coumarin with DPPC/DPPS lipid bilayer: effects of concentration and alkyl tail length.

In this work, interactions between amphiphilic amino methyl coumarin and dipalmitoyl-sn-glycero-3-phosphocholine/dipalmitoyl-sn-glycero-3-phosphoserine (DPPC/DPPS) lipid bilayer were investigated. A combination of experimental techniques (zeta potential, fluorescence spectroscopy, and differential scanning calorimetry) along with molecular dynamics simulations was employed to examine the influence of alkyl tail length and concentration of the amphiphilic coumarin on the lipid bilayer. Alkyl tails comprising 5(C5), 9(C9), and 12(C12) carbon atoms were conjugated to amino methyl coumarin via a single-step process. The binding and insertion mechanisms of the amphiphilic coumarins were studied in increasing concentrations for short-tailed (C5) and long-tailed (C12) coumarins. The simulation results show that C5 coumarin molecules penetrate the lipid bilayer, but owing to the short alkyl tail, they interact primarily with the lipid head groups resulting in lipid bilayer thinning; however, at high concentrations, the C5 coumarins undergo continuous insertion-ejection from the outer leaflet of the lipid bilayer. In contrast, C12 coumarins interact favorably with the hydrophobic lipid tails and lack the ejection-reinsertion behavior. Instead, the C12 coumarin molecules undergo flip-flops between the outer and inner leaflets of the lipid bilayer. At high concentrations, the high-frequency flip-flops lead to lipid destabilization, causing the lipid bilayer to rupture. The simulation results are in excellent agreement with the toxicity of amphiphilic coumarin activity in cancer cells. The efficacy of amphiphilic coumarins in liposomal lipid bilayers demonstrates the promise of these molecules as a tool in the treatment of cancer.

Flexible quantum dot light-emitting devices for targeted photomedical applications.

Quantum dot light-emitting devices (QLEDs), originally developed for displays, were recently demonstrated to be promising light sources for various photomedical applications, including photodynamic therapy cancer cell treatment and photobimodulation cell metabolism enhancement. With exceptional emission wavelength tunability and potential flexibility, QLEDs could enable wearable, targeted photomedicine with maximized absorption of different medical photosensitizers. In this paper, we report, for the first time, the in vitro study to demonstrate that QLEDs-based photodynamic therapy can effectively kill Methicillin-resistant Staphylococcus aureus, an antibiotic-resistant bacterium. We then present successful synthesis of highly efficient quantum dots with narrow spectra and specific peak wavelengths to match the absorption peaks of different photosensitizers for targeted photomedicine. Flexible QLEDs with a peak external quantum efficiency of 8.2% and a luminance of over 20,000 cd/m2 at a low driving voltage of 6 V were achieved. The tunable, flexible QLEDs could be employed for oral cancer treatment or diabetic wound repairs in the near future. These results represent one fresh stride toward realizing QLEDs' long-term goal to enable the wide clinical adoption of photomedicine.

Optogenetic regulation of transcription.

Optogenetics has become widely recognized for its success in real-time control of brain neurons by utilizing non-mammalian photosensitive proteins to open or close membrane channels. Here we review a less well known type of optogenetic constructs that employs photosensitive proteins to transduce the signal to regulate gene transcription, and its possible use in medicine. One of the problems with existing gene therapies is that they could remain active indefinitely while not allowing regulated transgene production on demand. Optogenetic regulation of transcription (ORT) could potentially be used to regulate the production of a biological drug in situ, by repeatedly applying light to the tissue, and inducing expression of therapeutic transgenes when needed. Red and near infrared wavelengths, which are capable of penetration into tissues, have potential for therapeutic applications. Existing ORT systems are reviewed herein with these considerations in mind.

Quantum dot light emitting devices for photomedical applications.

While OLEDs have struggled to find a niche lighting application that can fully take advantage of their unique form factors as thin, flexible, lightweight and uniformly large-area luminaire, photomedical researchers have been in search of low-cost, effective illumination devices with such form factors that could facilitate widespread clinical applications of photodynamic therapy (PDT) or photobiomodulation (PBM). Although existing OLEDs with either fluorescent or phosphorescent emitters cannot achieve the required high power density at the right wavelength windows for photomedicine, the recently developed ultrabright and efficient deep red quantum dot light emitting devices (QLEDs) can nicely fit into this niche. Here, we report for the first time the in-vitro study to demonstrate that this QLED-based photomedical approach could increase cell metabolism over control systems for PBM and kill cancerous cells efficiently for PDT. The perspective of developing wavelength-specific, flexible QLEDs for two critical photomedical fields (wound repair and cancer treatment) will be presented with their potential impacts summarized. The work promises to generate flexible QLED-based light sources that could enable the widespread use and clinical acceptance of photomedical strategies including PDT and PBM.

Red Light Modulates Ultraviolet-Induced Gene Expression in the Epidermis of Hairless Mice.

OBJECTIVE: The purpose of this study was to investigate whether low-level light therapy (LLLT) was capable of modulating expression of ultraviolet (UV) light-responsive genes in vivo. MATERIALS AND METHODS: The effects of 670 nm light-emitting diode (LED) array irradiation were investigated in a hairless SHK-1 mouse epidermis model. Mice were given a single dose of UVA/UVB light, or three doses of red light (670 nm @ 8 mW/cm(2) x 312 sec, 2.5 J/cm(2) per session) spread over 24 h along with combinations of pre- and post-UV treatment with red light. Levels of 14 UV-responsive mRNAs were quantified 24 h after UV irradiation by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). RESULTS: The transcription of mRNAs encoding for cluster of differentiation molecule 11b (CD11b) (p < 0.05) and interferon (IFN)-γ (p < 0.012) increased after irradiation with red light alone, whereas expression level of cyclooxygenase (COX)-2 (p < 0.02) was downregulated. Genes unresponsive to UV did not change their expression levels after exposure to red light either. Pretreatment with red light significantly modified response of Fos to UV exposure (p < 0.01). A synergy of UV and post-treatment with red light in reducing the transcription levels of CD11b (p < 0.05) and inducible nitric oxide synthase (iNOS) (p < 0.05) was observed. CONCLUSIONS: This is an initial observation that in mouse red light LLLT more often than not causes opposite gene expression changes or reduces those caused by moderate UVA-UVB irradiation.

Preliminary assessment of photoactivated antimicrobial collagen on bioburden in a murine pressure ulcer model.

OBJECTIVE AND BACKGROUND DATA: Overcoming bacterial antibiotic resistance requires alternative strategies. The ability of photoactivated collagen-embedded flavins (PCF) to reduce bioburden in infected pressure ulcers was investigated. DESIGN AND METHODS: Two pressure ulcers were created on the dorsum of female BALB/C mice (n=40, 35 g) maintaining a 5 mm skin bridge between lesions. Ulcers and surrounding skin were covered with Tegaderm™ and inoculated with 0.1 mL of 1 × 10(5) colony-forming units (CFU)/mL methicillin-resistant Staphylococcus aureus (MRSA). Fluid was permitted to reabsorb for 10 min. In experiment 1, one wound from each animal was treated using PCF and photoradiation (PCF+R, n=12) or photoradiation alone (R, n=11). Composite dressing-treated wounds received 1 × 1 cm PCF discs. Overlying Tegaderm was excised, and PCF was placed over the wound and again covered with Tegaderm. Wounds were irradiated at 455 ± 5 nm (350 mW, 1 cm spot diameter, 15 min) using a diode laser 10 min after placement. Controls received no PCF or photoradiation (C, n=12). Animals were euthanized 24 h post-therapy. Quantitative bacterial counts (CFU/g tissue) were determined. In experiment 2, composite dressing-treated wounds were irradiated at 455 ± 5 nm (350 mW, 1 cm spot diameter, 15 min) using a diode laser 10 min after daily PCF placement (0, 1, 2, or 3 treatments, n=8/group). Controls received no treatment. Wounds were cultured daily. Animals were euthanized on day 7 post-infection. Quantitative bacterial counts were determined. RESULTS: PCF+R significantly reduced bacterial counts at 24 h (experiment 1, p<0.0001; experiment 2, p<0.05). The bacterial counts in rats receiving photoradiation alone were no different from those of untreated controls (experiment 1, p=0.24). PCF+R produced a 2-3 log reduction in bacterial counts (experiment 2, p<0.001). Antibacterial effects increased with number of treatments, and persisted for several days post-therapy (p<0.002). CONCLUSIONS: PCF+R inhibited bacterial growth in this model. This effect increased with successive treatments, persisting several days post-therapy. Further studies to optimize this treatment modality are warranted.

A preliminary study of the safety of red light phototherapy of tissues harboring cancer.

OBJECTIVE: Red light phototherapy is known to stimulate cell proliferation in wound healing. This study investigated whether low-level light therapy (LLLT) would promote tumor growth when pre-existing malignancy is present. BACKGROUND DATA: LLLT has been increasingly used for numerous conditions, but its use in cancer patients, including the treatment of lymphedema or various unrelated comorbidities, has been withheld by practitioners because of the fear that LLLT might result in initiation or promotion of metastatic lesions or new primary tumors. There has been little scientific study of oncologic outcomes after use of LLLT in cancer patients. METHODS: A standard SKH mouse nonmelanoma UV-induced skin cancer model was used after visible squamous cell carcinomas were present, to study the effects of LLLT on tumor growth. The red light group (n=8) received automated full body 670 nm LLLT delivered twice a day at 5 J/cm(2) using an LED source. The control group (n=8) was handled similarly, but did not receive LLLT. Measurements on 330 tumors were conducted for 37 consecutive days, while the animals received daily LLLT. RESULTS: Daily tumor measurements demonstrated no measurable effect of LLLT on tumor growth. CONCLUSIONS: This experiment suggests that LLLT at these parameters may be safe even when malignant lesions are present. Further studies on the effects of photoirradiation on neoplasms are warranted.

Laparoscopic mesh fixation using laser-assisted tissue soldering in a porcine model.

BACKGROUND AND OBJECTIVE: Animal studies using open surgical models indicate that collagen solder is capable of fixation of surgical meshes without interfering with tissue integration, increasing adhesions, or increasing inflammation intraperitoneally. This study describes development of instrumentation and techniques for laparoscopic herniorrhaphy using laser-assisted soldering technology. STUDY DESIGN AND METHODS: Anesthetized 20 kg to 25 kg female Yorkshire pigs underwent laparoscopy with a 3-trocar technique. Parietex TET, Parietex TEC, and Prolene mesh segments (5 x 5 cm) were embedded in 55% collagen solder. Segments were inserted by using a specially designed introducer and affixed to the peritoneum by using prototype laser devices (1.45 micro, 4.5 W continuous wave, 5-mm spot, 55 degrees C set temperature) and a custom laparoscopic handpiece (IPOM). Parietex PCO mesh was inserted and affixed using the Endo-hernia stapler (Control). Animals were recovered and underwent second-look laparoscopy at 6 weeks. Mesh sites were harvested after animals were euthanized. RESULTS: The mesh-solder constructs were easily inserted and affixed in an IPOM approach. Prolene mesh tended to curl at its edges as the solder was melted. Postoperative healing was similar to that in Control segments in all cases. DISCUSSION AND CONCLUSION: Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce the use of staples or other foreign bodies for laparoscopic mesh fixation, prevent tissue ischemia and possibly nerve entrapment, which result in severe postoperative pain and morbidity. Laser-assisted mesh fixation is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted.

Transabdominal preperitoneal herniorrhaphy using laser-assisted tissue soldering in a porcine model.

BACKGROUND AND OBJECTIVES: Collagen solder is capable of fixation of surgical meshes during laparoscopic herniorrhaphy without compromising tissue integration, increasing adhesions or inflammation. This pilot study describes development of instrumentation and techniques for transabdominal preperitoneal (TAPP) herniorrhaphy using laser-assisted soldering technology. METHODS: Anesthetized 20-kg to 25-kg female Yorkshire pigs underwent laparoscopy performed using a 3-trocar technique. Peritoneal incisions were made and pockets created in the preperitoneal space for mesh placement. Parietex TEC mesh segments embedded in 60% collagen-solder were soldered to the muscle surface by using a prototype laser (1.45micro, 4.5W CW, 5mm spot, and 55 degrees C set temperature) and custom laparoscopic handpiece. Parietex TEC mesh segments (Control) were affixed to the muscle with fibrin sealant (Tisseel). Peritoneal closure was with staples (Control) or by soldering collagen embedded Vicryl mesh segments over the peritoneal incision (Mesh/TAPP). Segments were inserted using a specially designed introducer. Animals were recovered and underwent second-look laparoscopy at 6 weeks postimplantation. Mesh sites were harvested after animals were euthanized. RESULTS: The mesh-solder constructs were easily inserted and affixed in the TAPP approach. Tisseel tended to drip during application, particularly in vertical and ventral locations. Postoperative healing was similar to Control segments in all cases. Mesh/TAPP closures healed without scarring or adhesion formation. DISCUSSION AND CONCLUSION: Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce use of staples for laparoscopic mesh fixation and peritoneal closure. Laser-assisted mesh fixation and peritoneal closure is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted.

Pulsing influences photoradiation outcomes in cell culture.

BACKGROUND AND OBJECTIVES: Skin pigmentation can adversely affect phototherapy outcomes. Delivering pulsed light has been suggested as a means of enhancing efficacy. Suitable pulse frequencies remain indeterminate, often being selected empirically. This study was undertaken to determine whether pulsed light delivery mitigates the filtering effect of melanin pigment on photomodulation in vitro. STUDY DESIGN AND METHODS: Human HEP-2 cells were cultured in complete DMEM media. Photoradiation was delivered through 0.025% melanin filters at 670 nm (5.0 J/cm(2)/treatment/24 hours) for 72 hours at different pulse rates. Group A received no light treatment. Group B received treatments without pulsing. Groups C, D, E, F, and G received treatments at 6, 18, 36, 100, and 600 Hz. Cell proliferation was assessed by MTT assay and oxidative burst was measured using the 2.7 dichloro-fluorescein-diacetate assay. RESULTS: Cell proliferation was maximally stimulated at 100 Hz at 48 and 72 hours (n = 4, P< or =0.05). Oxidative burst was maximally stimulated at 600 Hz (n = 4, P< or =0.05). All frequencies were stimulatory at 48 and 72 hours (n = 4, P< or =0.05). CONCLUSION: This investigation suggests that light pulsing may improve outcomes by mitigating the filtration effects of cutaneous melanin. Further studies to further define these effects are warranted.

Reciprocity of exposure time and irradiance on energy density during photoradiation on wound healing in a murine pressure ulcer model.

BACKGROUND: Energy density and exposure time reciprocity is assumed and routinely used in low-level light therapy (LLLT) regimens. This study examined dose reciprocity effects on wound healing. METHODS: Pressure ulcers were created on seven groups of C57/BL mice (n = 18). Photoradiation was administered (18 days; 5 J/cm(2)/day @ 670 nm) using a custom LED apparatus and treatment matrix varying both intensity and exposure. Control animals were treated similarly, without photoradiation. Ulcer staging was performed using a standardized scale. Changes in stage, wound area and wound closure rates were measured. Histology was performed. RESULTS: Photostimulatory effects at day 7 occurred with parameters of 125 seconds @ 40 mW x 1/day; 625 seconds @ 8 mWx1/day; 62.5 seconds @ 40 mWx2/day; and 312.5 seconds @ 8 mWx2/day; and at day 18 using 625 seconds @ 8 mW and 312.5 seconds @ 8 mWx2/day. Statistically significant increases in wound closure rates occurred using 625 seconds @ 8 mW; 62.5 seconds @ 40 mWx2/day; and 312.5 seconds @ 8 mWx2/day treatments. Mean ulcer grade scores were similar to controls. CONCLUSIONS: Varying irradiance and exposure time to achieve a specified energy density affects phototherapy outcomes in this model. Variation of exposure time and irradiance may account for conflicting results in the literature. Further studies of these effects are warranted.

Melanin density affects photobiomodulation outcomes in cell culture.

OBJECTIVE: This study investigated the influence of melanin on the outcome of photoradiation at 670 nm in a cell culture model. BACKGROUND DATA: Melanins are naturally occurring cutaneous pigments. Human skin is classified into six skin types based on melanin content. METHODS: Gelatin photo filters were fabricated with varying melanin contents. Human HEP-2 and murine L929 cell lines were cultured in complete Dulbecco's Modified Eagle's Medium (DMEM) media. Photoradiation at 670 nm delivering 5.0 J/cm(2) per treatment/24 h (50 J/cm(2) total fluence) was carried out with melanin filters placed between the light source and the wells using a light-emitting diode (LED) device. Five groups based on percent melanin were treated: group 1, no filter; group 2, gelatin alone; group 3, 0.0125%; group 4, 0.025%; and group 5, 0.050%. Cell proliferation was measured using CyQuant and 3-(4,5-dimethylthiazol-2-yl)-2,5-disphenyl tetrasodiumbromide (MTT) assays for 240 h post-photoradiation. RESULTS: The Proliferation Index (PI) as measured by CyQuant assay was not statistically different amongst the groups in either cell line. MTT assay results demonstrated a significant dose response effect (p < or = 0.05) in both cell lines with activity inversely proportional to melanin concentration. The relative PI values by MTT assay at 144 h for groups 1, 2, 3, and 4, respectively, were 1.44 +/- 0.06, 1.28 +/- 0.05, 1.20 +/- 0.07, and 1.06 +/- 0.04 for the L-929 cells, and 1.61 +/- 0.03, 1.47 +/- 0.06, 1.35 +/- 0.03, and 1.19 +/- 0.06 for the HEP-2 cells (n = 4; p < 0.05). CONCLUSION: These results demonstrate that cutaneous melanin content should be taken into consideration in photobiomodulation paradigms. Further studies to quantify these effects are warranted.

Histologic assessment of mesh fixation following laser-assisted tissue soldering in a lapine model.

OBJECTIVE: Wound histology and mesh bioincorporation following intraperitoneal fixation using laser-assisted soldering was evaluated. METHODS: 2.8-3.2 kg NZW rabbits underwent laparotomy. Controls had 2x2 cm segments of Mersilene stapled to peritoneum. Group 2 segments were affixed with 55% collagen solder onlay by fiber-coupled diode laser (1.43 +/- 10 micro, 2.5 W CW, 4 mm spot, 60 degrees C set temperature). Group 4 had Mersilene inlaid into melted solder. Group 3 had solder-embedded Vicryl mesh affixed. Animals were euthanized at 0, 2, 4, 6 weeks. Fixed sections were assessed for integrity, inflammation, and fibrosis using H & E, Masson's Trichrome and Evans Van Gieson staining. RESULTS: Histology demonstrated cell types, local mesh reaction, and progressive evidence of solder reabsorption mimicking normal healing and bioincorporation. Mersilene groups demonstrated normal arrangement of collagen-rich layers around mesh. CONCLUSION: Collagen-based tissue soldering permits normal wound healing and may mitigate use of staples. Further development of this strategy is warranted.

A study of the effects of phototherapy dose interval on photobiomodulation of cell cultures.

BACKGROUND AND OBJECTIVES: Dosimetry and treatment frequency are controversial phototherapy issues. Efficacy of dose fractionation on photobiomodulation was evaluated in vitro. STUDY DESIGN/MATERIALS AND METHODS: Human HEP-2 and murine L-929 cell lines were cultured in complete DMEM media. Photoradiation (670 nm, 5 J/cm2/treatment, 50 J/cm2 total energy delivery), was performed varying treatments per 24 hour period: Group I (Controls)-0, Group II-1/d, Group III-2/d, Group IV-4/d. Cell proliferation was measured using Cyquant (fluorescent DNA content) and MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrasolium bromide) assays for 240 hours post therapy. A proliferation index: PI = (#Cells Experimental(t) / #Cells Control(t)) was computed. RESULTS: MTT assay results demonstrated maximal response in Group III (P < 0.05, n = 3). Cyquant maxima occurred in HEP-2 Groups II and III (P < 0.045) and L-929 Group III (P < 0.091). CONCLUSIONS: Cellular response to dose frequency varies. More frequent treatments (2/24 hours) increased metabolism and proliferation in both cell lines. Further investigation of dose fractionation in phototherapy is warranted.

Preliminary assessment of postoperative adhesion formation after laser-assisted mesh fixation to the peritoneal surface.

OBJECTIVE: This study evaluated the incidence and persistence of adhesions following intraperitoneal onlay mesh fixation with tissue soldering in an experimental model. METHODS: Anesthetized New Zealand white rabbits (n = 21), weighing 2.8-3.2 kg, underwent laparotomy. Controls (group 1 [n = 3]) had 2 x 2 cm Mersilene (Ethicon, Somerville, New Jersey) polyester mesh segments fixed to the peritoneum with staples (USSC, Norwalk, Connecticut). Group 2 (n = 7) rabbits had Mersilene mesh affixed by melting 55% collagen solder using a prototype laser (1.43 micro, 2.5 W CW, 4 mm spot size, 60 degrees C set temperature) over mesh. Group 3 (n = 6) rabbits had Vicryl (Ethicon, Somerville, New Jersey) polyglactin mesh embedded in 60% collagen solder placed onto the peritoneum and fixed with identical laser parameters as group 2. Group 4 (n = 5) rabbits had 55% collagen solder placed and Mersilene pressed into it after melting. Four segments were placed in each experimental animal. Animals were euthanized at 2, 4, or 6 weeks. Adhesions were graded (0 = none; I = filmy adhesions; II = omental; III = bowel adhesions gently lysed; IV = dense adhesions requiring sharp dissection). RESULTS: Grade III adhesions were observed in both control and group 4 animals at 2 weeks, persisting in group 4 animals at 6 weeks, but having lysed in controls at 6 weeks. No adhesions were present in group 3 specimens at any interval. Grade I adhesions were present in group 2 at 2 weeks at exposed mesh areas, and declined in frequency at 6 weeks. Evidence of reabsorption of the polyglactin mesh-solder composite was apparent in the group 3 specimens at 4 weeks, and complete resorption had occurred by 6 weeks postoperatively. DISCUSSION: Laser-assisted solder fixation caused minimal adhesion formation when mesh was covered by solder. Adhesions were observed if Mersilene mesh material was exposed to the abdominal contents. Vicryl mesh-solder composites reabsorbed without inflammation, scarring, or adhesions at the sites of mesh fixation. CONCLUSION: Further development of this technology is warranted.

Development of a simple, noninvasive, clinically relevant model of pressure ulcers in the mouse.

The formation of pressure ulcers and other skin wounds is considered to be a multifactorial process. Cycles of ischemia-reperfusion have been considered to be significant contributing factors in the pathogenesis of pressure ulcers. This study reports the development of a reproducible murine model of ischemia-reperfusion injury by the external application of magnets. Mice were sedated with 50% CO2:50% O2 for 50-60 s. Dorsal hair was shaved and the area cleaned. The skin was gently pulled and placed between two round ceramic magnetic plates (5 x 12 mm diameter, 2.4 g weight, 1000 G magnetic force). The resultant "pinch" procedure was designed to leave a 5-mm skin bridge between the magnets, creating 50 mm Hg pressure between the plates. Three 12-h ischemia-reperfusion cycles were employed to cause pressure ulcer formation. Animals tolerated the procedure well. They returned to normal activity a few minutes after magnet placement. The lesions reached their maximum at 10 days postinjury. Full-thickness skin loss with damage and necrosis of subcutaneous tissue (ulcer stage 3) was observed in all cases, reaching a mean stage score of 3.6 +/- 0.6 of based on a 0-5 scale for extent of injury by visual assessment. Thus, an inexpensive, reproducible murine pressure ulcer model was developed, which results in graded injury without long-term immobilization of the animals. This method will facilitate the development of new prevention and management strategies.

Alteration of skin temperature during low-level laser irradiation at 830 nm in a mouse model.

OBJECTIVE: This study investigated the change in local skin temperature in black and white mice during irradiation at 830 nm. BACKGROUND DATA: The photostimulation effect low-level laser therapy (LLLT) (700-900 nm) is widely accepted and used. However, the exact biological mechanisms of biostimulation are not yet established. MATERIALS AND METHODS: Groups of C57BL/6J and BALB/cJ mice (n = 12 in each group) were lightly anesthetized with 50% carbon dioxide and 50% oxygen. The dorsum was shaved and a 1.0 x 0.5 cm spot was marked in the same location on each subject. Animals were photo-irradiated with a diode laser (CW, 830 nm, 36 mW output at 5 cm distance). Fluences of 0.0-5.0 J/cm(2) were delivered. Skin surface temperature was monitored by a thermal camera. Two thermocouples were placed 1 mm below the skin surface at the site of light exposure. RESULTS: Temperature increased with increasing fluences of exposure. The surface temperature change at 5.0 J/cm(2) was 6.25 x 10(-2) +/- 2.0 x 10(-3) vs. 1.2 x 10(-2) +/- 3.0 x 10(-3) degrees C/mW for black and white mice, respectively. The temperature change at 1.0 mm depth was 4.51 x 10(-2) +/- 3.0 x 10(-3) vs. 0.83 x 10(-2) +/- 1.0 x 10(-3), respectively. CONCLUSION: CW irradiation at 830 nm and 5.0 J/cm(2) fluence induces a small temperature increase at the surface and at 1 mm in depth. The smaller effects seen in white mice might be due in part to reflection. This suggests that the thermal effects of irradiation at 830 nm are unlikely to explain the LLLT effect. However skin color should be considered, particularly at higher fluences. Further investigations are warranted to correlate the melanin content of the skin with observed LLLT effects.

Temperature-controlled 830-nm low-level laser therapy of experimental pressure ulcers.

OBJECTIVE: This study was performed to evaluate the effectiveness of near-infrared low-level laser therapy (LLLT) treatment of pressure ulcers under temperature-controlled conditions. BACKGROUND DATA: Little information is available regarding the potential thermal effects of near-infrared photo-radiation during LLLT. METHODS: Pressure ulcers were created in C57BL mice by placing the dorsal skin between two round ceramic magnetic plates (12.0 x 5.0 mm, 2.4 g, 1 K Gauss) for three 12-h cycles. Animals were divided into three groups (n = 9) for daily light therapy (830 nm, CW, 5.0 J/cm(2)) on days 3-13 post ulceration in both groups A and B. A special heat-exchange device was applied in Group B to maintain a constant temperature at the skin surface (30 degrees C). Group C served as controls, with irradiation at 5.0 J/cm(2) using an incandescent light source. Temperature of the skin surface, and temperature alterations during treatment were monitored. The wound area was measured and the rate and time to complete healing were noted. RESULTS: The maximum temperature change during therapy was 2.0 +/- 0.64 degrees C in Group A, 0.2 +/- 0.2 degrees C in Group B and 3.54 degrees C +/- 0.72 in Group C. Complete wound closure occurred at 18 +/- 4 days in Groups A and B and 25 +/- 6 days in Group C (p

A preliminary study of laser tissue soldering as arterial wall reinforcement in an acute experimental aneurysm model.

BACKGROUND AND OBJECTIVES: Aneurysm formation results from destruction of structural arterial wall connective tissue, leading to wall weakening and rupture. The purpose of this study was to demonstrate that reinforcement of the arterial wall using laser tissue soldering contributes to arterial wall stabilization and rupture prevention in an acute experimental model. STUDY DESIGN/MATERIALS AND METHODS: Elastase (10 U/mg protein, Sigma-Aldrich Co., St. Louis, MO) was applied with a fine paint brush on femoral artery segments to cause fusiform aneurysm formation. After aneurysms formed (approximately 45 minutes after treatment), elastase was rinsed out and indocyanine green (ICG) and albumin soldering mixture (2.5 mg/ml ICG in 50% albumin) was delivered to the arterial segment, followed by laser irradiation at 830 nm, (15mW output for 20 minutes). In situ pressure burst measurements were then performed. RESULTS: In situ burst pressures were > 503 mmHg for normal arteries and 181 +/- 26.0 mmHg, for Elastase treated segments. (P < 0.0001) Treatment of experimental aneurysms laser tissue soldering returned burst strengths to > 503 mmHg. CONCLUSIONS: These results indicate laser tissue soldering reinforcement of weak arterial walls, is possible and may reduce the likelihood of acute rupture. Further development of this technique for aneurysm management is warranted.

Reducing toxicity of cisplatin in cancer chemotherapy by extracorporeal removal of excess cisplatin.

Cisplatin and its derivatives are today among the most frequently used agents for treatment of malignancies, the dose, however, is limited by side effects. When an organ or extremity with tumor has a single, well defined artery, cisplatin can be delivered into the tumor, and cisplatin leaving the tumor through the venous drainage can be removed before it empties into the systemic circulation. We developed a hollow fiber device with an immobilized platinum chelator for extracorporeal removal of cisplatin, without the chelator entering the blood. When blood from melanoma patients, obtained during cisplatin infusion, was circulated through the device, 80% of the cisplatin was removed. In experiment using dogs cisplatin (100 mg/m2) was infused into the femoral vein, thus restricting cisplatin to the area to be treated. This method allows for applying high cisplatin doses locally, while reducing systemic side effects.