OBJECTIVE: Laser irradiation of cultured cells is a valuable technique for elucidating the mechanisms of low-level laser therapy, but is often tedious because of the need to manually change the position of the laser beam. Consequently, we developed a computer-based system that automatically moves a cell culture plate over a laser beam and times the exposure. BACKGROUND DATA: There are presently no commercial devices available for automated laser irradiation of cultured cells. Many investigators thus manually aim and time laser exposure, a time-consuming task that is prone to errors. MATERIALS AND METHODS: We used outdated, surplus computer components to construct a system for automated laser exposure of cultured cells. This design strategy makes the system quite inexpensive. RESULTS: Construction and operation of the system is described and an example of its use is presented. Alternate means of accomplishing automated laser irradiation are also presented. CONCLUSION: Inexpensive and relatively simple devices can be constructed for automated laser irradiation of cultured cells. These devices can eliminate the tedium and errors of manual laser exposure.

Automation↗

PubMed2004

The efficacy of laser therapy in wound repair: a meta-analysis of the literature.

OBJECTIVE: We determined the overall effects of laser therapy on tissue healing by aggregating the literature and subjecting studies meeting the inclusion and exclusion criteria to statistical meta-analysis. BACKGROUND DATA: Low-level laser therapy (LLLT) devices have been in use since the mid sixties, but their therapeutic value remains doubtful, as the literature seems replete with conflicting findings. MATERIALS AND METHODS: Pertinent original research papers were gathered from library sources, online databases and secondary sources. The papers were screened and coded; those meeting every inclusion and exclusion criterion were subjected to meta-analysis, using Cohen's d. statistic to determine the treatment effect size of each study. RESULTS: Twenty-four studies with 31 effect sizes met the stringent inclusion and exclusion criteria. The overall mean effect of laser therapy on wound healing was highly significant (d = +2.22). Sub-analyses of the data revealed significant positive effects on wound healing in animal experiments (d = +1.97) as well as human clinical studies (d = +0.54). The analysis further revealed significant positive effects on specific indices of healing, for example, acceleration of inflammation (d = +4.45); augmentation of collagen synthesis (d = +1.80); increased tensile strength (d = +2.37), reduced healing time (d = +3.24); and diminution of wound size (d = +0.55). The Fail-Safe number associated with the overall effect of laser therapy was 509; a high number representing the number of additional studies-in which laser therapy has negative or no effect on wound healing-required to negate the overall large effect size of +2.22. The corresponding Fail-Safe number for clinical studies was 22. CONCLUSION: We conclude that laser therapy is an effective tool for promoting wound repair.

Animals↗

PubMed2004

The efficacy of low-power lasers in tissue repair and pain control: a meta-analysis study.

OBJECTIVE: We used statistical meta-analysis to determine the overall treatment effects of laser phototherapy on tissue repair and pain relief. BACKGROUND DATA: Low-power laser devices were first used as a form of therapy more than 30 years ago. However, their efficacy in reducing pain or promoting tissue repair remains questionable. METHODS: Following a literature search, studies meeting our inclusion criteria were identified and coded. Then, the effect size of laser treatment, that is, Cohen's d, was calculated from each study using standard meta-analysis procedures. RESULTS: Thirty-four peer-reviewed papers on tissue repair met our inclusion criteria and were used to calculate 46 treatment effect sizes. Nine peer-reviewed papers on pain control met the inclusion criteria and were used to calculate nine effect sizes. Meta-analysis revealed a positive effect of laser phototherapy on tissue repair (d = +1.81; n = 46) and pain control (d = +1.11; n = 9). The positive effect of treatment on specific indices of tissue repair was evident in the treatment effect sizes determined as follows: collagen formation (d = +2.78), rate of healing (d = +1.57), tensile strength (d = +2.13), time needed for wound closure (d = +0.76), tensile stress (d = +2.65), number and rate of degranulation of mast cells (d = +1.87), and flap survival (d = +1.95). Further, analysis revealed the positive effects of various wavelengths of laser light on tissue repair, with 632.8 nm having the highest treatment effect (d = +2.44) and 780 nm the least (d = 0.60). The overall treatment effect for pain control was positive as well (d = +1.11). The fail-safe number-that is, the number of studies in which laser phototherapy has negative or no effect-needed to nullify the overall outcome of this analysis was 370 for tissue repair and 41 for pain control. CONCLUSIONS: These findings mandate the conclusion that laser phototherapy is a highly effective therapeutic armamentarium for tissue repair and pain relief.

Female↗

PubMed2002

Glycation-induced matrix stability in the rabbit achilles tendon.

Connective tissue susceptibility to nonenzymatic glycation was examined following 0, 2, 4, 6, 8, and 10 weeks of incubating the rabbit Achilles tendon in phosphate-buffered saline containing ribose (glycated). The biomechanical integrity of the glycated tendons was then compared to control tendons incubated in phosphate-buffered saline (non-glycated) at each time interval, while the biochemical stability of both groups of tendons was determined by examining collagen extractability and the formation of pentosidine at 8 weeks. Whereas there were no significant biomechanical differences between control and glycated tendons at 0- and 2-week intervals (P > 0.05), moderately significant increases in maximum load, energy to yield, and toughness of glycated tendons were observed at 4 weeks. Beyond 4 weeks of incubation, the differences between glycated and non-glycated tendons became highly significant, as glycated tendons withstood more load and tensile stress (P < 0.01 for each variable), attained significantly higher modulus of elasticity (P < 0.01), absorbed more energy (P < 0.01), and became tougher (P < 0.01) than controls. These differences in the biomechanical indices of the effects of glycation were stable between the 6th and 10th week of glycation. The maximum increases in the biomechanical measurements as a result of glycation were 29% for maximum load, 125% for stress, 19% for strain, 106% for Young's modulus of elasticity, 14% for energy to yield, and 57% for toughness. Biochemical analysis showed a 61% reduction in the extractability of neutral salt-soluble collagen, a 48% decrease in acid-soluble collagen, and a 29% decline in pepsin-soluble collagen in glycated tendons (P < 0.01). In contrast, there was a 28% increase in the amount of insoluble collagen and significantly higher amounts of pentosidine (P < 0.01) in glycated tendons. Collectively, these biomechanical and biochemical results suggest that nonenzymatic glycation may explain the altered stability of connective tissue matrix induced by the processes of diabetes and aging.

Achilles Tendon↗

PubMed2002

Soft tissue thermodynamics before, during, and after cold pack therapy.

BACKGROUND: Cold packs are commonly used by clinicians, trainers, and others, often as an interim treatment for many acute conditions, but the extent of temperature change associated with this form of treatment remains poorly understood. METHODS: In 16 healthy male and female volunteers aged 25.4 +/- 3.6 yr, we monitored skin temperature, and recorded the temperature of the quadriceps muscle at 1, 2, and 3 cm depths below the skin, before, during, and after 20 min of cold pack treatment. RESULTS: The results revealed a slight rise in temperature at all four levels during the 5 min pretreatment period, but significant temperature falls at the skin and 1 cm levels beginning from 8 min of treatment (P < 0.001). There was no significant change in tissue temperature at the 2.0 cm or 3.0 cm depths throughout treatment. However, after treatment, cutaneous temperature and the temperature at 1.0 cm depth rose rapidly, returning to baseline levels at variable intersubject times. As these superficial temperatures rose, there were concurrent falls in the temperatures at the 2.0 cm and 3.0 cm levels. Thus, the deeper tissues lost heat (cooled) simultaneously as the superficial tissues rewarmed; to the extent that 40 min after treatment, the deeper levels were cooler than the cutaneous and 1.0 cm levels. CONCLUSION: 1) Cold pack therapy produces significant temperature falls in cutaneous and subcutaneous superficial tissues without directly changing the temperature of tissues at or more than 2.0 cm below the skin; and 2) the temperature gradients of both layers of tissue reverses after treatment, indicating that the deep tissue beneath is at least one of the sources of heat used to rewarm the cooled superficial tissue. The latter finding underscores the importance of the hemodynamic interchange between superficial and deep tissues, and offers an explanation for the reduction of pain, muscle spasm, and edema observed with cold therapy in several clinical situations.

Adult↗

PubMedDate not supplied

Therapeutic light.

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Humans↗