The use of low-energy helium-neon laser irradiation has recently attracted attention concerning the treatment of nerve injury. Studies in the rat optic nerve have yielded several key observations which support the notion that treatment with low-energy laser is beneficial to injured rat optic nerves, provided that all parameters are well-calibrated and optimal. Irradiation employing a nonoptimal parameter could have either a devastating effect or no effect at all. Most laser irradiation studies using calibrated parameters have employed an electrophysiological setup in which measurements of compound action potential are carried out 2 weeks after injury. After this time period the electrophysiological activity of the injured treated nerve itself is very low, so that any beneficial effect resulting from any treatment is detectable.

This overview paper will focus on different model approaches being developed by the FSU scientists to get better insight into the LELE problems. We shall point out the fields of medicine in which the application of LELI was proved to be most efficient, discuss the possibilities of raising the therapeutic efficiency. Examples of most commonly used and perspective equipment for LELT being developed and produced in Russia will be presented.

The use of laser light in biostimulation studies raises the issue of the uniqueness of laser light. Are such effects related to the qualities unique to laser light or a manifestation of photic exposure effects on biological systems in general? In this paper, we have reviewed studies in the ocular low level light exposure effects area. Several papers suggest a unique role for coherent stimulation regarding low level light effects on vision. Long term deficits in visual function may result from either large discrepancies in peak to average power, neural fatigue from unique neural stimulation, stimulation of basic energy sensitive biochemical neural systems. These effects have implications for biostimulation investigations and could underlie the effectiveness of low level long wavelength coherent light exposure.

Complete reporting of the physical parameters and laser exposure conditions in laser biomodulation research is essential to understand interaction mechanisms and permit the replication of the results or the extension of their scientific use. Often the biological parameters and procedures are described in detail and physical parameters pertinent to the exposure dose are inappropriately or ambiguously reported. The paper summarizes the minimal physical parameters that should be reported to describe the exposure dose and their measurement. These include the irradiance, the radiant exposure, the exposure duration, the effective irradiated area (e.g. beam diameter if circular), the intensity profile of the radiation field, wavelength(s) or wavelength band, the number of exposures, the time between exposure and a schematic of the exposure apparatus.

The healing effect of low energy lasers is generally attributed to enhanced cell proliferation due to the irradiation. As it was not clear whether coherent irradiation is essential, we examined the effect of various wavelengths from non-coherent light sources, on fibroblasts proliferation. We found that light at 540 and 600 - 900 nm significantly accelerates the mitosis of these cells. Moreover, we have found that the effect is not only energy-dose dependent, but depends non-linearly on the intensity of the light source.

Laser irradiation at subthreshold energies has various effects on the eye and other body systems. These bioeffects are manifested mostly in the morphology of the retina but also on other ocular tissue. This review will summarize these effects as well as some reports claiming that low energy laser irradiation has a beneficial effect on many eye diseases including keratitis, glaucoma and macular degeneration. The flaws in some of these reports will be delineated and proposal for future research will be made.

To investigate the mechanism of cell photostimulation, we measured oxygen consumption of mitochondria during low-intensity laser irradiation at various wavelengths in vitro. Isolated guinea-pig liver mitochondria were irradiated with a low-intensity argon laser irradiation at the wavelength of 351 nm, 458 nm, and 514.5 nm. Both 351 nm and 458 nm irradiations increased the mitochondrial oxygen consumption on state 4 respiration in spite of no effect on state 3 respiration. The 514.5 nm irradiation activated the mitochondrial oxygen consumption on state 3 respiration in spite of no influence on state 4 respiration. These results might be explained that the ultraviolet irradiation causes damage to the mitochondrial inner-membrane, and the 514.5 nm irradiation enhances ATP-synthesis.

The effectiveness of low-intensity light for clinical therapies is well demonstrated, however, the principles of these therapies are not well understood. Our aim of this study is the investigation of optical properties of mitochondria because it seems to be the most important cellular organella in terms of the light-cell interaction. We measured the optical absorption characteristics of an isolated mitochondrial suspension in the range of 300 to 900 nm by means of the transmission methods with an integral sphere. Mitochondrial specific absorption coefficients (ml/g/cm^-1) were carried out by the transmission spectrum. The specific absorption coefficient at the maximum absorption of cytochrome c_(gamma ) peaked about 560 ml/g/cm^-1 at 418 nm. Many papers described that the effect of the low intensity light to the biological tissue would be drastically changed by the irradiation conditions. We could calculate a deposit energy of irradiated light in a mitochondrion from our results. We think our results may be useful to describe the quantitative explanation in energy balance for the interaction between the light and mitochondria.

A specific electrode was made of quartz optic fibers with a thin metal membrane, the quartz core guided nitrogen laser beam (10 - 40 (mu) j/pulse, I pulse/sec.) into brain cortex, and got out fluorescent pulses emitted by brain NADH and FAD moleculars. The amplitudes of laser- fluorescent pulses represented brain NADH and FAD concentrations determined by HPLC methods. The metal membrane outside optic fiber (1*10 micrometers ², 40 mm long) as a specific electrode recorded neural discharges. The neural pulses represented neuron activities. The ratio of frequency changes of neural discharges to the amplitude changes of laser- fluorescent pulses was written as (eta) equals dF_i/dA_i, which (eta) means neuron efficiency. The results showed that intensity of nitrogen beam increased the amplitudes of laser-fluorescent pulses and decreased the (eta) value. Electric stimuli increased the frequency of neural discharges and increased the (eta) value. The results mean that low power laser beam guided into brain by optic fibers can work as a stimulant factor as well as a probe to brain function.

Two basic biological functions have been investigated: cell proliferation and metabolic processes. A culture of human lymphocytes was subjected to irradiation with light of various doses and wavelengths. Spontaneous lymphocyte proliferation was studied, as well as proliferation in response to mitogenic stimulation by phytohemagglutinin (PHA). A parallel investigation has been devoted to metabolic energy supplying process, in particular to enzyme (myosin ATPase) reactivation. Common features and mechanisms underlying this complex phenomenological response are discussed.

The study was performed to establish the influence of low energy red ((lambda) equals 633 nm) laser radiation on some rheological parameters of blood irradiated in vivo as well as in vitro.

To gain further insight into the mechanism of cell photostimulation by laser light ((lambda) equals 632.8 nm), DNA synthesis was measured in the human neuroblastoma cell line BE(2)-C. Cells were irradiated at high density to establish the characteristics of cellular energy into S- phase in response to laser stimulation. BE(2)-C cells after release from a quiescent, growth arrested state exhibited increased incorporation of isotope 12 hours after replating at subconfluent density in the presence of 2.5% fetal bovine serum (FBS) and [³H] thymidine. In contrast, cells replated under the same conditions, but stimulated with 15% FBS exhibited a time lag of approximately 16 hours in apparent DNA synthesis. These results were not corroborated by flow cytometry. Laser irradiation did not affect the fraction of cells entering S-phase. It therefore appears that the stimulatory effect of He-Ne laser irradiation on BE(2)-C cells is to enhance DNA synthesis while not altering the G₁-S transition rate.

Optical medium-nonperturbing methods are proposed controlling the aggregational and morphological characteristics as well as the functional states of cell chromophores (derivatives of haemoglobin and a number of proteins) under different physical-chemical actions, including laser therapy. The investigations have shown that the parameters' changes depending on the degree of a disease (atherosclerosis) and the character of changes during laser therapy seances are individual, which permits revealing patients with contraindication or absence of susceptibility to such seances.

The effect of low-energy laser irradiation, known to delay axonal degeneration in mechanically traumatized nerves, was investigated in rabbit retinal ganglion cells damaged by temporary anoxia. Complete retinal vascular occlusion was induced in 39 rabbits by application of pressure to the cornea, with continuous monitoring under an operating microscope. The duration of occlusion was 15, 30 or 60 minutes. Starting immediately after the cessation of vascular occlusion, half of the rabbits in each group received transcorneal irradiation with a 35-mW helium-neon laser for 5 minutes daily on 10 consecutive days. The nonirradiated rabbits served as controls. Retinal ganglion cell viability was demonstrated by retrograde labeling of their axons with horseradish peroxidase, introduced subdurally into the optic nerve at a distance of 2 mm distal to the globe, 48 hours prior to sacrifice. For labeling intensity controls we used normal, not occluded, animals labeled with horseradish peroxidase by the same method. The animals were sacrificed 2, 4 or 8 weeks after occlusion. Labeling of retinal ganglion cells and their axons was observed in 100% of the normal control animals and in 85% of the irradiated rabbits. The results suggest that low-energy helium-neon laser irradiation attenuates the damage inflicted on the retinal ganglion cells as a result of anoxia.

The comparative studies of SLR effects vs chemical adaptogens effects on animals poisoned by industrial poisons and SLR as compared to traditional radio-protectors effects on gamma- irradiated animals were carried out. Obtained results show the stressed adaptogenous effect of SLR.

Intravenous 337 nm laser irradiation of blood results in an essential increase of rabbits' organism immunity against staphylococcal infection. It has preventive as well as therapeutical effect.

Structural and functional microcirculatory changes in tissues and organs (muscles, liver, derma, epinephros, brain cortex) under various dosages and powers of laser irradiation in the red (633 nm) and near infrared (890 nm) spectrum regions have been studied in experiments and clinic. In case of nonsensitized tissues the `photoactivation' range of power densities and doses of laser irradiation has been established. We have identified a short-term reaction of microvessels and a long-term reaction (adaptation). The former consists of intensification of microcirculation and metabolism rise in parenchymatous cells; the latter is connected with neoangiogenesis acceleration. The intensification of the blood microcirculation includes a dilation of microvessels of all orders, an amplification of arteriolar vasomotions and an opening of `reserved' capillaries. Data on the structural reconstruction of myocytes and endotheliocytes have shown that the high differential parenchymatous cells and its membrane structures are sensitive to low energy laser irradiation and, on the other hand, under low energy laser irradiation there is an activation of synthetic processes in the cells. Thus, during the laser-tissue interaction in such complex system as human organism the microcirculation plays the key role among the other systems.

Local influence of low intensive laser irradiation (LILI) of Helium-Neon (HNL), Copper vapor (CVL), Nitrogen (UVL) and Arsenic Gallium (AGL) lasers cause stimulation of processes of physiological and reparative regeneration in intact skin, and mucous membrane of stomach and duodenum, dermatome wounds and gastroduodenal ulcers. Structural bases of these effects are the acceleration of cell proliferation and differentiation and also the activation of intracellular structures and intensification of cell secretion. Regional influence of the pointed types of LILI on hepar in cirrhosis and hepatitis causes decreasing of the inflammatory and cirrhotic changes. After endo- and exo-vascular laser irradiations of blood the decreasing of the number of pathological forms of erythrocytes and the increasing of their catalase activity, are indicated. General (total) laser irradiation of the organism--laser shower, increases the bone marrow cells proliferation, especially myeloid series. It is accompanied with acceleration of their differentiation and migration in circulation. It was revealed, that HNL to a considerable extent influences the epithelial cells and CVL the connective tissue cells. UVL increases the amount of microorganisms on cell surfaces (membrane bound microorganisms). Regional irradiation of the LILI causes both direct and indirect influence of cells. Structural changes of bone marrow cells and gut mucous membrane cells indicate intersystemic interaction.