Macrophages are a source of many important mediators of wound repair. Cells of an established macrophage-cell line (U-937) were exposed in vitro to an 820 nm light source which was both coherent and polarized. the power densities used being either 400 mW/cm² or 800 mW/cm². The irradiation times were such that the energy densities to which the cells were exposed were 2.4 and 7.2J/cm² for both probes. Twelve hours after exposure the macrophage-conditioned medium was removed and placed on 3T3 fibroblast monolayers. Fibroblast proliferation was assessed over a four-day period. By four days after the addition of medium conditioned by macrophages exposed to an energy density of 2.4 J/cm², there was a statistically significant difference in fibroblast number between the 400 mW/cm²- and 800 mW/cm² treatments, 800mW/cm² producing greater cell proliferation. However. there was no significant difference between the effects of sham irradiation and 400 mW/cm². In contrast, after the addition of medium conditioned by macrophage exposed to an energy density of 7.2 J/cm², 400 mW/cm² treatment produced a significantly greater increase in fibroblast number than sham irradiation. There was no significant difference in cell number between the sham irradiated and 800 mW/cm² irradiated samples, although there was a significant difference between the 400 mW/cm2 and the 800 mW/cm². 400 mW/cm² producing greater cell proliferation.

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Based on our previous experimental investigation^1-9 which indicated that low-level laser irradiation has a significant therapeutic effect and treatment potential on the injured nerve tissue, we began using this method in clinical practice. This. study represents our first clinical results in the treatment of four patients with tethered spinal cord resulting from fibrous adhesions at the site of previous myelomeningocele and lypomyelomeningocele repair, thickened filum terminale and spinal lipoma. After surgical release of the tethered spinal cord, stable evoked responses were recorded and the conus medullaris was subjected to direct laser irradiation (CW He-Ne laser, 632.8 nm, 7 J/cm²). We found that intraoperative laser treatment increases evoked responses from 15-52% (mean 26.7%). In a previous work, we showed that direct laser irradiation promotes restoration of the electrophysiological activity of the severely injured peripheral nerve, prevents degenerative changes in neurons of the spinal cord and induces proliferation of astrocytes and oligodendrocytes.^5-8 This suggested a higher metabolism in neurons and improved ability for myelin production under the influence of laser treatment. The tethering of the spinal cord causcs mechanical damage to neuronal cell membranes leading to metabolic disturbances in the neurons, For this reason, we believe that using low-level laser therapy (LLLT) may improve neuronal metabolism, prevent neuronal degeneration and promote improved spinal cord function and repair.

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Thc effect of Infrared-Laser radiation (IR-L) on white rat thyroid ‘C’ cells was studied structurally employing toluidine blue staining of semifine slice, and immunohistochemically employing staining to demonstrate and assay the presence of somatostatin and calcitonin. There were 55 rats in the study population. Ten animals served as unirradiated controls, and the remaining 45 animals were divided into irradiated experimental groups receiving single exposure IR-L doses ranging from 10 J/cm² to 60 J/cm², with periods between the single irradiation to killing of 2, 8 and 15 days, Thyroid tissue from the IR-L treated animals demonstrated an increase in the ‘C’ cell population, and immunohistochemical hyperactivity with signs of calcitonin. Additionally, with low doses of radiation, some somatostatin activity was also noted, This last peptide was. isolated in the thyroid gland of the experimental irradiated animals only at an age which somatostatin is usually not present. All these changes decreased or disappeared with the passage of time. In the present study. the possible mechanisms are discussed which explain the presence of somatostatin in thyroid ‘C’ cells taken from l3-l5-week-old female Wistar rats.

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Current laser safety measures are usually aimed at prevention of accidental direct radiation of the eye by a laser beam. Laser action target area in tissue can often be compared with that of a gun barrel. Direct projectile launching is accompanied by diffuse examinations of light and shock waves. When a laser beam is incident on tissue, or indeed any target substance, the diffuse reflection of high peak power and high repetition rate pulses may induce premature senile cataracts in those working with lasers, so that it is necessary to take comprehensive precautionary measures against chronic eye injury, for example establishment of laser safety devices and the wearing of specific laser goggles to protect against laser diffuse reflection.

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San Diego was once again the site for the 11th meeting of the American Society for Laser Medicine and Surgery (ASLMS), the 10th anniversary meeting of this association. It was held in the Sheraton Harbor Iland, San Diego. California, form April 29th to May 1st 1991. inclusive. The reviewer has been at every one of these except the first meeting in 1911, and it is very interesting to review the programmes over the past 10 meetings That he has attended. Especially as far as the gradual separation of photobioactivation studies and clinical laser therapy papers into their own category of ‘biostimulation’, This year, the Biostimulation Session Programme Chairperson was Dr Juanita J. Anders. , of the Uniformed University of the Health Science, Bethesda. Maryland, Dr Anders has produced a number of excellent studies which by and large show a significant LLLT effect on nerve and related structures compared with controls. Thirteen papers were scheduled for presentation during this session, extended at Dr Anders' request to allow a fuller representation of what is happening in the LLLT world; unfortunately the Russian group (Vestibulo-dependence tachyarrhythmias, and treatment results using HeNe laser: V. Zalessy. I. Michalkin and V. Bobrov) and the Argentinian group (Blockade of inflammatory signals by laser radiation: J. Palma. H. Juri, V. Camapna et al.) were ‘no-shows ’. However this did mean that there was in fact mere time at Dr Anders' disposal to allow for more detailed discussion after the papers, and for an unscheduled free forum at the end of the session.

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