It was long assumed that visible (≈ 380 ∼ 650 nm) and near infrared (I.R.) (≈ 650 nm ∼ 1000 nm) light does not interact with tissue. In the past three decades, however, it has been found that lasers in the visible and near I.R. cause biostimulation of injured tissues at very low levels of incident energy. We therefore studied the effect of various light sources in the visible (540 nm, 630 nm,) and near I.R. (660 nm, 780 nm, 940 nm,) on fibroblasts and keratinocytes. We found that at certain low energy doses there is an enhancement in their proliferation. Since these two radiation regions differ dramatically in their photochemical and photophysical properties, we share the opinion that visible light starts the cascade of metabolic events after being absorbed by endogenous porphyrins in the mitochondria, whereas infrared radiation starts the cascade of metabolic events by activating enzymes in the membranes. In order to examine our hypothesis that biostimulation in the visible is a photosensitization process, we measured the proliferation rate of fibroblasts enriched with very small amounts of hematoporphyrin derivatives (HPD) after HeNe (633 nm) irradiation and 940 nm irradiation. We have found that the effect of HeNe light on fibroblast proliferation was dependent on exogenous HPD while that of 940 nm was not. These results have important implications in both phototherapy and photodynamic therapy (PDT).

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∗The activation effect of the nitrogen laser (wavelength = 337.1nm) with an energy density of 5.4 J/cm² and exposure time of 15 minutes was studied in vitro on the biocidal efficiency of human neutrophils on internalized bacteria. Experimental models used previously have ruled out the direct inactivating effect of the nitrogen laser on bacteria. Experiments were conducted where the neutrophils were irradiated only after phagocytosis of Staphylococcus aureus had occurred. An identical group of unirradiated neutrophils handled in exactly the same way as the irradiated group served as the control. The surface adherent and non-phagocytosed S. aureus were inactivated by a novel approach of gentamicin treatment during washing. The results convincingly proved the accelerated destruction of the internalized phagocytosed bacteria in those neutrophils exposed to nitrogen laser in comparison to the non-irradiated controls.

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In patients with cerebral palsy of the tension athetosis type, a number of symptoms may be observed, including not only the fairly constant involuntary athetotic movements but also myotonic disorders of the motor function of all four limbs and trunk, vocalization and motions associated with eating such as mastication and swallowing. Aggravation of involuntary movements and pain in the neck and back are also seen in many cases. Existing conservative treatment methodologies have proved to be more or less ineffective, and limitations in functional training in adults have made treatment extremely difficult. We first employed low reactive-level laser therapy (LLLT) in a case of spastic cerebral palsy in 1994 with good results. In the present study, we applied laser irradiation (830 nm. 60 mW continuous wave) to all myotonic sites around the face and neck region where myotonia was severe in 20 patients with cerebral palsy of the adult tension athetosis type for which there was no effective treatment for their neck and back pain. Improvement of myotonia was seen in 19 patients while improvement of pain in the neck and back was seen in all the 16 patients who had pain in these regions. Suppression of myotonia reduced tonic vocalization making words easily heard; moreover, suppression of myotonia and involuntary movements improved working efficiency enabling the patient to perform fairly complex tasks such as word processing. Insomnia and dysuria also improved. Even in the most severe cases, assisting the patient became easier and breathing improved. LLLT with the 830 nm diode laser provides a new and effective treatment modality in this extremely problematic condition, has no serious side effects, and has the potential to improve these patients’ quality of life.

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The dura mater over the pituitary was surgically exposed in both experimental and control male Wistar rats, and the anterior lobe of the pituitary in the experimental animals was transdurally irradiated with the HeNe laser (2.75 ± 0.25 mW, C/W, total energy 0.825 J). Following pituitary hyperactivity produced by the low incident doses of laser energy, type II Leydig cells in the central region of the testicle in the experimental animals presented an acceleration in cellular maturation, which was shown in the evolution from Type I to Type II. Electron microphotography is presented to demonstrate the changes.

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The failure of drugs in the treatment of tuberculosis is very frustrating for the physicia n. In recent years scientists in Russia (the former USSR) have reported on and developed a method of endocavitary nitrogen laser irradiation of patients having the cavitary form of pulmonary tuberculosis. The nitrogen laser acts by emitting ultra violet light which is bacteriocidal for tuberculosis bacilli. The present study reports on ten patients with pulmonary tuberculosis which was sputum positive for acid fast bacilli, The patients included drug-resistant cases. The nitrogen laser probe was introduced directly into the tuberculous cavity percutaneously. In order to improve the imnune mechanisms of these patients, helium-neon laser was also given intravenously. Three out of ten patients became sputum negative for M. tuberculosis. However, further extensive studies and research work is required to evaluate this new modality of therapy in the treatment of pulmonary tuberculosis.

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From June 1990 to June 1993, 18 patients with gastrointestinal type urticaria (GU) were treated with helium neon (HeNe) laser acupoint therapy (LAT). As a control group, 17 patients with GU were treated with the corticosteroids cortisol (CT) or dexamethasone (DX) and the results were compared. The patients’ ages ranged from 3∼59 years, with a mean age of 31 years. In the HeNe laser group, the ‘shenque ’ acupoints were irradiated once daily with 25 mW continuous wave (632.8 nm) for 10 ∼15 minutes per session, at an incident power density of 800 mW/cm² giving an incident energy density of 480 ∼720 J/cm². The results showed that 11 patients were cured and 6 greatly improved. The total effective rate for HeNe LAT was 94.1%. In the CT and DX therapy groups, the drugs were administered by intravenous drip or injected intramuscularly. The results showed 8 patients cured and 7 greatly improved. The total effective rate was 88.2%. In comparison with the two chemotherapeutic groups, the total effective rate of the HeNe group was statistically significantly higher than that of the controls (p = > 0.05). Although more controlled experimental work is required to elucidate the LAT mechanisms and pathways, this preliminary study indicates that noninvasive and side effect free HeNe LAT might be more effective for the treatment of GU, especially for those cases with have proved resistant to CT or GX therapy, and for the paediatric patient.

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