W Yu

Rochester General Hospital, Rochester, New York, United States

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Publications (7)14.39 Total impact

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    ABSTRACT: Low-level laser irradiation has been applied in a variety of laboratory studies and clinical trials for photobiostimulation over the last three decades. Considerable skepticism exists regarding the concept of photostimulation within the medical community. One of the major difficulties with photoirradiation research is that it lacks experimentally supportable mechanisms for the alleged photobiostimulatory effects. This study was undertaken to determine whether oxidative metabolism and electron chain enzymes in rat liver mitochondria can be modulated by photoirradiation. Oxygen consumption, phosphate potential, and energy charge of rat liver mitochondria were determined following photoirradiation. Activities of mitochondrial enzymes were analyzed to assess the specific enzymes that are directly involved with the photostimulatory process. An argon-dye laser at a wave-length of 660 nm and at a power density of 10 mW/cm2 was used as a photon source. Photoirradiation significantly increased oxygen consumption (0.6 J/cm2 and 1.2 J/cm2, P < 0.05), phosphate potential, and the energy charge (1.8 J/cm2 and 2.4 J/cm2, P < 0.05) of rat liver mitochondria and enhanced the activities of NADH: ubiquinone oxidoreductase, ubiquinol: ferricytochrome C oxidoreductase and ferrocytochrome C: oxygen oxidoreductase (0.6 J/cm2, 1.2 J/cm2, 2.4 J/cm2 and 4.8 J/cm2, P < 0.05). The activities of succinate ubiquinone oxidoreductase, ATPase, and lactate dehydrogenase were not affected by photoirradiation.
    Photochemistry and Photobiology 12/1997; 66(6):866-71. · 2.29 Impact Factor
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    ABSTRACT: Late sepsis causes immunosuppression and is associated with energy depletion in lymphocytes. Adjuvant treatment with ATP-MgCL2 appears to improve cellular energetics and decrease mortality. Laser irradiation can promote cell proliferation and increase cellular ATP synthesis, which may improve the host immune response in sepsis. The purpose of this study was to determine whether laser irradiation (LI) has a stimulatory effect on the immune response in sepsis using an animal model. The cecal ligation and puncture (CLP) rat model was used. Thirty-six SD rats were divided equally among four groups: control (nonoperative), sham operation, CLP treated with laser irradiation, and CLP without laser irradiation. The peritoneal cavity of each animal in CLP/laser group was irradiated immediately after CLP using an Argon-dye laser at a wavelength of 630 nm and at a fluence of 5 J/cm2. Some animals were euthanized 24 hr following CLP and were used to evaluate the immune response (lymphocyte proliferation). In a separate experiment, the survival of septic rats was observed for 60 days. Lymphocytes isolated from normal rat spleens were used to observe for biostimulatory effects in vitro. LI significantly improved ex-vivo lymphocyte proliferation of cells from septic rats (179.7 +/- 17.2 vs. 129.5 +/- 7.8; P < 0.01) and enhanced survival in septic rats (79% vs. 42%; P < 0.001). LI significantly stimulated lymphocyte proliferation in the presence of mitogenic stimuli and enhanced lymphocyte ATP synthesis (P < 0.05). LI improves the host immune response and survival rate in sepsis in an animal model. Our studies suggest that LI may be useful as an adjuvant therapy for sepsis.
    Lasers in Surgery and Medicine 01/1997; 21(3):262-8. · 2.46 Impact Factor
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    ABSTRACT: Photo-irradiation causes a variety of effects in different cells and tissues. We hypothesized that photo-irradiation may improve cardiac preservation based on these observations. For pre-storage treatment (Pre), the heart in an anesthetized open-chest rat was irradiated using an Argon-dye laser with a wavelength of 660 nm at a fluence of 16.8 J/cm2 or sham-operated. The heart was excised, perfused with Krebs-Henseleit Buffer, cardioplegically arrested, and stored by immersion at 0 degree C for 18 hrs. Functional recovery was evaluated by working reperfusion for 30 min. For post-storage treatment (Post), the isolated hearts were stored for 18 hrs at 0 degree C; laser irradiation at a fluence of 36 J/cm2 was administered during working reperfusion. Hearts which did not receive irradiation during reperfusion served as control. Furthermore, isolated cardiomyocytes were used to study laser effect on cellular ATP content, catalase activity, and nitric oxide (NO) release. Both Pre and Post groups showed significant improvement in recovery of aortic flow, cardiac output, and work compared to the corresponding control groups (P < 0.05). Combined Pre/Post laser treatment did not improve function. Investigation using isolated rat cardiomyocytes found that both end-storage ATP and end-reperfusion catalase activity in the laser-treated group were significantly higher than those in the untreated cells (P < 0.05). NO release increased by 15% in the laser group after 18 hrs of 37 degrees C incubation. Photo-irradiation improves functional recovery of the cold-stored rat heart possibly via conservation of ATP and antioxidant enzyme activity.
    Lasers in Surgery and Medicine 01/1997; 20(3):332-9. · 2.46 Impact Factor
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    ABSTRACT: Low-level laser irradiation at certain fluences and wavelengths can enhance the release of growth factors from fibroblasts and stimulate cell proliferation in vitro. We evaluated whether low-level laser irradiation can improve wound healing in diabetes mellitus. Genetically diabetic mice (C57BL/Ksj/db/db) were used as the animal model for this wound healing study. The experimental animals were divided among four groups: negative control, positive control (topical basic fibroblast growth factor [bFGF] on wound), laser therapy group; and a combination group of laser therapy and topical bFGF. An argon dye laser (Lexel Auora Model 600) at a wavelength of 630 nm and an output of 20 m W/cm2 was used as the light source. The speed of wound closure and histological evaluation were used to analyze the experimental results. Laser irradiation enhanced the percentage of wound closure over time as compared to the negative control group (58.4 +/- 2.6 vs. 40.8 +/- 3.4 at day 10 and 95.7 +/- 2 vs. 82.3 +/- 3.6 at day 20, P < .01). Histological evaluation showed that laser irradiation improved wound epithelialization, cellular content, granulation tissue formation, and collagen deposition in laser-treated wounds as compared to the negative control group (6.4 +/- 0.16 vs. 3.8 +/- 0.13 at day 10 and 12 +/- 0.21 vs. 8.2 +/- 0.31, P < .01). This study of laser biostimulation on wound healing in diabetic mice suggests that such therapy may be of great benefit in the treatment of chronic wounds that occur as a complication of diabetes mellitus.
    Lasers in Surgery and Medicine 01/1997; 20(1):56-63. · 2.46 Impact Factor
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    ABSTRACT: This study was undertaken to determine if methotrexate (MTX) is effective against tumor cells surviving photodynamic therapy (PDT). C6 rat glioma cells were exposed to Photofrin and irradiated at 630 nm using power densities of 1.2 or 4.8 J/cm2 to simulate the conditions for cells in solid tumors which survive PDT. Cells were then treated with MTX at 5.0, 0.5, or 0.05 microM concentrations. MTT assay of cell proliferation was performed at 24, 48, 72, and 96 h postirradiation. During the first 48 h of incubation, MTX alone was more effective than PDT and MTX. After 48 h, the combination treatment was more effective. Further studies of combined PDT and chemotherapy are warranted.
    Journal of Clinical Laser Medicine & Surgery 05/1996; 14(2):55-8.
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    ABSTRACT: Studies have shown that low-level laser irradiation increases the proliferation of fibroblasts in cell culture. The mechanism of action is unknown. Basic fibroblast growth factor (bFGF) is a multifunctional polypeptide that has been detected in most tissues and which supports cell proliferation and differentiation. The purpose of this study was to determine whether laser irradiation (660 nm) can stimulate production of bFGF from fibroblast cells in cell culture. Our study showed that fibroblasts irradiated with laser energy at 2.16 J/cm2 demonstrated increased cell proliferation and enhanced production of bFGF, whereas fibroblasts irradiated with laser energy at 3.24 J/cm2 neither demonstrated increased cell proliferation or an enhanced release of bFGF as compared to the control group. These results provide direct evidence that the proliferation of fibroblasts as a result of stimulation by low level laser irradiation may be associated with the autocrine production of bFGF from fibroblasts.
    Photochemistry and Photobiology 03/1994; 59(2):167-70. · 2.29 Impact Factor
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    ABSTRACT: Growth factors are a group of hormone-like polypeptides that have been shown to play a central role in different phases of wound healing. The expression of these growth factors in early wound healing has not been quantified, and the pattern and distribution of these growth factors in early wound healing has not been described completely. Furthermore the quantity and pattern of distribution of these growth factors have not been investigated in early wounds produced by various methods of surgical incision. Comparison of the rate of healing between the CO2 laser wound and the scalpel wound has produced conflicting results. The present immunohistochemical study uses polyclonal antibodies specific for epidermal growth factor (EGF), platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), and basic fibroblast growth factor (bFGF) to observe the pattern and distribution of these growth factors in rat skin wound and elucidate whether there are differences in the expression of these growth factors which might account for the delayed healing of the CO2 laser wounds compared to the scalpel as has been observed by some authors. Our results indicate that EGF, TGF-beta, PDGF, and bFGF are expressed and distributed in same areas of the early skin wound. The area of expression of these growth factors was associated with presence of wound inflammatory cells and wound fibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)
    Lasers in Surgery and Medicine 02/1994; 15(3):281-9. · 2.46 Impact Factor