Characteristics and optical schematics of medical lasers and laser-fiber systems for medicine are considered. A short description of light interaction with different kinds of human biotissues is done. Some examples of lasers and fiber optics applications in diagnostics and therapy are represented.

The kinetics of aggregation and disaggregation of red blood cells in whole blood subjected to shear stress is different with normal and pathological blood. To measure this kinetics, we have applied a backscattering nephelometric technique, and quantitatively registered the alteration of the scattered intensity due to appearance or disappearance of different types of cell aggregates under controlled shear stresses. Fresh samples of normal and pathological blood from 25 patients suffering psoriatic arthritis were tested and showed differences in the RBCs (dis)aggregation kinetics. Relaxation times, index of hydrodynamic durability, and anisotropy of light scattering along and across to flow were discussed.

A newly developed system to determine red blood cell flexibility is presented. It combines ektacytometry (laser diffraction) with image analysis. Laser light is passed through erythrocyte suspensions which are sheared in a Cuette like viscosimeter. The laser diffraction patterns are photographed by a CCD camera, and further analyzed by a computer. Flexibility is characterized by the quotient of minor and major axes of isointensity lines of the elliptically transformed diffraction patterns. The variation coefficient of the measurement is less than 1%.

The effects of laser radiation on human organism are experimentally shown to be identifiable from optical (absorption K and extinction coefficients, mean cosine <x> of the phase function of scattering, and value q/E, where qequals1/3(1-<x>) and temporal statistical characteristics of light being multiple scattered by blood.

Methods of optical shifting spectroscopy and laser nephelometry may be used to register antigen-antibody reaction. Usage of laser nephelometry in serodiagnostics, characteristics of a specific step in humoral immune reaction in infections, postinfectious and postinoculation processes response and immunity tension in some infectious diseases were investigated.

Several alternative solutions of the inverse problems of quantitative analysis of a wide range of disperse systems by means of elastic light scattering method are discussed. The possibilities are considered for the optimization of the spectroturbidimetric method as a tool in studying of the structurally complex biological and synthetic suspensions with due consideration for the unavoidable restrictions on spectral interval width and the body of a priori information for real systems.

The paper deals with analyzing the angular and spectral characteristics of repeatedly scattered radiation. Multiple scattering theory is used to study single light scattering on one spherical particle transformed to obtain intensity expression via the parameter of scattering particle immediately, without calculating the amplitudes.

A theoretical aspect of frequency domain measurements of tissue optical parameters is considered. In the framework of radiative transfer theory the expressions have been obtained, which describe dependence of modulation M and phase shift (Delta) (Theta) of scattered radiation on frequency. As an example, the results of processing of experimental data are presented.

In-vivo measurements of nonstationary blood flows in Dannio Rerio fish embryo have been performed using laser Doppler microscopy technique. Time-dependences of the velocity of pulsatile blood flow in arteria and veina of the embryo have been registered by monitoring the heterodyne energy spectra of the Laser Doppler Microscope signal, generated by light scattered by moving erythrocytes. The spectral characteristics of the registered signal are discussed.

An instrument based on laser interferometry to measure fundus pulsations on the eye is presented. The eye is illuminated with a laser beam, which is reflected partially at the cornea and partially at the retina. The resulting interferences include information of the distance changes between cornea and retina. In contrast with existing techniques laser interferometry is a noncontact method and more convenient for the patient. Pulse amplitudes of normal subjects are presented and compared to results in different stages of diabetic retinopathy.

Resonance Raman spectrum of carotene in human blood serum was obtained. The decrease in carotene lines intensities after UV laser irradiation of serum was observed.

A set for fluorescence detection of picosecond laser-induced processes in biological tissues in the spectral range from 200 nm to 1000 nm is described. Examples of the set application to model biological objects - mice tumors, decorated by tumor-marking agents - mixtures of sulphonated phthalocyanine MePcS, where M equals Al, Nd, Eu, Gd, in spectral and image modes of operation are given.

The new method of numeric processing of analogous signals of EEG based on chaotic synchronization phenomena is suggested. A quantitative measure of synchronization is proposed. It is shown that this method can be used both for analysis of functioning regimes and for diagnostics of human brain pathology.

A new quantitative electrocardiogram characteristic is introduced as a distribution entropy, normalized by the signal energy. A perspective of this parameter application as a diagnostic criterion is proved by series of test experiments. By way of comparison with traditional medico-biological characteristics the higher sensitivity and stability of this criterion is proved.

The sex differences in cardiovascular system responses to a mild noise stress are established using the physiological and the dynamic systems theory methods. Lower levels of basal systolic arterial pressure and higher rates of its dropping and normalization under influence and after its cessation are typical for women. There are no hypertensive responses to stresses in women in contrast to men. The normalized entropy of the ECG signal, describing the physiological variability, increases in women and decreases in men. The advantages of female cardiovascular system response to mild stresses are discussed.

In this paper the investigations of the dependence of the space-time projection structure and probability function form of speckle-interferometer output signal on heart disease seriousness have been carried out. The noval technique of heart disease diagnostic is suggested. The results of experimental investigations of pulse waves, using the differential speckle- interferometer are present. The traditional speckle-interferometer Michelson type and differential speckle-interferometer for cardiovibration measurements are compared. The difficulties, appearing by using suggested diagnostic method, are analyzed and ways to eliminate it are found.

This paper looks at paramagnetic centers formed under UV-illumination at 77 K in cells, plasma, and serum of human blood. ESR signals of these centers were separated from complex spectra-superposition with the use of stage heating method and computer analysis of spectra. The differentiation of summary spectra of UV-illuminated blood components in composite signals and study of their features give a ground for understanding of the nature of UV-induced PC that in its turn is necessary for investigation of molecular mechanism of blood photomodification.

The capacity of erythrocytes to photohemolysis was researched in physiological solution with increasing percents of blood plasma by spectrophotometer Specord UV-VIS. The screening effect of plasma was founded during illumination of erythrocyte suspensions by completed light of the mercury lamp DRT-375. Much less effect was observed during the illumination of the light with (lambda) equals 365 nm. The screening effect of plasma was due to presence of a protein and aminoacid groups in plasma.

This paper discusses some of our experimental results on the organism immunity increase caused by an intravenous UV irradiation of blood. The rabbits from an experimental group were treated with an optical fiber (620 micrometers core diameter) introduced to vena auricularis superficialis lateralis of the rabbits' ear. Pulsed UV laser emission was introduced through the optical fiber and rabbits' blood was irradiated for 10 minutes with the pulse repetition rate of 10 Hz. Subsequently, all rabbits from the experimental and a reference group were infected with the virulent strain of Staphylococcus aureus H 470. These results clearly indicate that the intravenous UV laser irradiation of blood had a positive therapeutic effect on the course of the animals' staphylococcal infection.

It has been found experimentally that exposure to a low-intensity light changes the human blood plasma absorption spectrum in the range 350 - 550 nm. The action of violet light and green light have opposite directions. The times of development of photoinduced effects are in the order of dozens of seconds, the times of spectrum relaxation after the exposure are in the order of dozens of minutes. Dependences have been studied of the effect on the intensity, dose, and wavelength of the acting light. A phenomenological model is developed which describes qualitatively the experimentally observed effects.

We present here the first results of comparative spectral analysis of the marrow and blood taken from one and the same donor and consider the new potentialities of the spectroscopic method for hematologic diseases diagnostics and for testing the pathologic process together with the morphologic investigations of marrow punctates.

Blood of male mice of CBA line was irradiated by He-Ne laser in vitro (wave-length - 632.8 nm, 3.8 mW/cm², 30 min). After irradiation, glycogen and lipid content in neutrophils is decreased, SDH and ATP-ase activity is increased, and alkaline phosphatase inhibition is observed. Antimicrobial potential of neutrophils is increased, that being proved by the increase of myeloperoxidase activity, formation of diformazan in NBT-test, and lysosomal cationic proteins content increase. ATP-ase activity in lymphocytes is increased. In monocytes lipid content is decreased; activity of membrane oxygen-dependent processes and ATP-ases is increased.

Contents of diene, triene conjugate, and malonic dialdehyde in blood plasma and erythrocytes, activity of superoxide dismutase and catalase in erythrocytes and the level of plasma ceruloplasmin in short-term immobilization stress and combined action of immobilization and low power laser irradiation were studied on white rats in experiments.

In the present paper the method and apparatus for percutaneous laser irradiation of blood (PLIB) in vessels (veins) and for irradiation of not large skin tumors are described. The problems of laser light dosimetry by irradiation of tissues are discussed. Results of clinical investigations of biostimulating effects under PLIB by red laser light (633 nm) in Cubiti and Saphena Magna veins are presented.

The version of Monte Carlo method for modelling optic radiation propagation in a biotissue or scattering medium based on using Green's function of media response to single external disturbance is described. The algorithm allows us account for three-dimensional geometry of media, an incident beam finite size, and light reflection and refraction on the boundaries between media with different refractive indices.

Authors use a conventional parameter `Specific Power Density', P<sub>s</sub> (mW/cm<sup>3</sup>) connected with both power characteristics of laser and optical properties of irradiated blood. This value is normalized intensity of laser emission in the irradiated blood volume. The suggested value of the `Specific Power Density' creates more reproductive and physically more correct understanding of parametrization of Intra-Venous Low Level Laser Therapy of blood.

The mathematical model is presented of low-intensity laser radiation influence on the dynamics of the X-irradiated bone marrow tissue erythropoiesis. The process of recovering in postradiation stage of the cells of erythroid series has been investigated for various parameters of laser emission.

This paper presents the results of experimental studies of laser irradiation effects on state of non-specific immunologic defense mechanism in wound process dynamics. Changes of biologically active products of vital activity of mononuclear phagocytes, like lysozyme, (beta) -lysin and complement, have been detected. Pathomorphological investigations have been performed also.

The potentions of laser intravascular therapy in elimination of pyogenic and inflammatory intoxication in cases of acute pneumonia, pyo-destructive diseases (including posttraumatic diseases) of the lungs are studied clinically.

Endovascular laser therapy (EVLT) with the help of the light-conductor was carried out for 30 minutes every day. The treatment consisted of 5 - 7 sessions. 56 patients suffering from ishemic brain stroke (IBS) and dyscirculatory once phalopathy (DE) were examined. A total systems approach was used to study the influence of the EVLT on the state of hemocirculation, lipid metabolism and immunoreactivity. It has been shown that EVLT provoked the suppression of LP, the extraction of cholesterol from the cells membrane, the positive changes in the system of microcirculaton and the improvement of the clinical state of the patients with the cerebrovascular diseases (CVD).

The present histological and stereological studies are on thyroid glands of Wistar rats irradiated with an IR laser. The animals were exposed to total doses of 46,80 J/cm², and sacrificed at 1, 40, and 180 days after the last treatment. A morphological and stereological study was made on follicular epithelium, follicle, stroma, and capillary. The laser beam produced an increase of follicular epithelial volume and hyperplasia of follicular cells in the animals sacrificed at 1, 40, and 180 days after the last treatment. Capillary dilation underwent a progressive decrease as time passed. It was higher in the animals sacrificed after 24 hours, then it decreased after 40 days and finally disappeared after 180 days.

We have examined the results obtained from the stereological ultraestructural study of follicular cells in thyroid glands treated with IR laser (904 nm). We studied 40 wistar rats exposed to radiation with doses of 46,80 J/cm2. They were sacrificed 1 and 180 days after the treatment. A stereological study of the volume and surface density was made in mitochondria, rER. Gogi complex and cytoplasmic granules. In the rats sacrificed 1 day after exposure to laser radiation, the thyrocited showed minimal morphological changes. In the rats sacrificed after a long period (180 days) the thyrocites showed a significant increase of volume and surface densities of rER, that may mean decreased capacity of the cells to synthesize thyroglobulin. Volume and surface densities of the citoplasmic granules experienced a significant increase.

The potentialities of computer-aided diagnostic al system `Diacoms' as a screening test for vertebral pathology detection for posterior prescription of laser reflexotherapy.

The purpose of this work was the investigation of the effects of UV and IR laser irradiation on the central and regional hemodynamics of agricultural mechanization workers with border limited arterial hypertension, whose arterial pressure was within the limits from 140 to 90 mm of mercury column up to 159 and 94 mm mercury column.

The design and function potentialities of the electric and laser stimulator of biologically active points on human skin surface are described.

The effects of laser radiation on human organism are experimentally shown to be identificable from optical (absorption K and extinction coefficients, mean cosine <xj< of the phase function of scattering, and value q/, where qz1/3(1-<x<) and temporal sticstical characteristics of light being multiple scattered by blood.

The transmission and reflection spectra of tissues (the lungs, liver, muscles, skin) and layers composed of th.se tisss in the 600-900nm range have been investigated. The experirents are accoinpanied by theoretical calculations. The method of layer addition i applied with the use of analytical asyrnptottc solutions of the theory of radiation transfer for weakly absorbing rnedia.A satisfactory agreement between theory and experiment is observed. The optimum conditions for observing structures situated at different depths in the muscular tissue are analysed. Much considerations i given to correct determination of the elementary volume used !or calcu1atiig transmitted and reflected by inultilayer structures radiation.

One of the main means of studying the essence of the laws of process dynamics in living systems is mathematical modelling. Construction of adequate mathematical models is not quite simple a problem and demands joint efforts of physicists, mathematicians, medical men, and biologists. Models can be of different levels of complexity. I would like to confine this discussion to only one of the dynamical processes description methods, that is, by means of ordinary differential equations. At the same time we will not consider spatiatemporal (wave) processes that are the subject for a separate discussion.

We will focus attention primarily on linear processes from the viewpoint of the living object dynamical behavior, though speculation on the questions concerned with nonlinear optical phenomena emerging at a sufficient intensity of light is also welcome.