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Biomedical subjects

T Karu

Publications and source records attributed to T Karu.

17 recordsLinked to original sources
PubMed2001

Acute immune response in respect to exercise-induced oxidative stress.

The relationship between exhaustive exercise, oxidative stress, the protective capacity of the antioxidant defense system and cellular immune response has been determined. Exhaustive exercise in well-trained young men (n=19)-induced leukocytosis, decreased proportion of activated-lymphocyte subsets (CD4+ and CD8+) expressing CD69, decreased lymphocyte mitogenic response to concanavalin A (ConA) and phytohemagglutinin (PHA), increased lipid peroxidation, increased total antioxidant status (TAS) and catalase activity, immediately after exercise. Suppressed blood concentration of T-lymphocyte subsets (CD3+, CD4+, CD8+, NK), increased TAS and blood total glutathione (TGSH) in early recovery period (30 min after exercise) were found. Strong positive correlation was observed between TGSH and lymphocyte mitogenic response to ConA and PHA (r=0.85 and 0.85, respectively) immediately after exercise. Moderate positive correlation was observed between TAS and lymphocyte mitogenic response to PHA (r=0.59) immediately after exercise as well as between TAS and lymphocyte mitogenic response to PHA and ConA (r=0.69 and 0.54, respectively). Moderate to weak correlation was observed between TAS and conjugated dienes with exercise (r=0.66) as well as in 30-min recovery (r=0.50). After a short-term bout of exhaustive exercise, immune system was characterized by acute phase response, which was accompanied with oxidative stress. Suppression of the cellular immunity 30 min after exercise shows that this period is not enough for recovery after exhaustive exercise. The results suggest the interactions between exercise-induced oxidative stress and immune response.

Journal Article↗
PubMed2001

Blood lactate recovery and perceived readiness to start a new run in middle-distance runners during interval training.

The aim of this study was to establish to what extent ratings of perceived readiness to start a new run are dependent on recovery of blood lactate and heart rate during passive recovery between interval runs (4 x 2000 m) of increasing intensity by 15 male college-level middle-distance runners. The Perceived Readiness Rating scale was administered at each minute of recovery. Blood lactate concentration was measured immediately after runs at Min. 3 of recovery after the first and second runs, and, in addition, at Min. 6 of recovery after the third and fourth runs. Heart rate was recorded continuously during the runs and during recovery. The obtained correlation between blood lactate recovery and perceived readiness ratings after the third and fourth runs were -.36 and -.56, respectively (p<.05). Consequently, blood lactate concentration recovery appears to influence the middle-distance runners' perceived readiness estimation to begin a new run. The Perceived Readiness Rating applied by us appears useful in the training of middle-distance runners.

Adolescent↗
PubMed2000

Relationship between perceived readiness to run and physiological variables during repeated 2000 m bouts in middle-distance runners.

The aim of this study was to investigate how heart rate (HR) and blood lactate (LA) concentrations are associated with perceived readiness ratings (PRR) to begin a new run during recovery after four different intensity steady-state 2000 m runs in college-level male middle-distance runners (n=15). A typical 4x2000 m run test with stepwise increasing speed was used on the indoor track (150 m lap). A new PRR scale was administered at each minute of recovery. The scale ranges from 1 to 5 points (from "not at all ready to begin" to "completely ready to begin"). Blood LA concentrations were measured immediately after runs and in the 3rd min of recovery after the first and second runs. In case of the third and fourth runs, blood LA was measured immediately after the runs and in the 3rd and 6th min of recovery. HR was recorded at the end of every minute of recovery. Highly significant inverse relationships were revealed between PRR, blood LA concentrations and HR during recovery (r>0.9 as a rule). After the third and the fourth 2000 m runs, where intensity was higher than LA threshold, PRR increased during 6 min up to 4.8+/-0.4 and 4.5+/-0.6, respectively, while HR fell below 120 beats x min(-1). However, blood LA concentration remained high. The reliability of the new PRR scale (tested on four runners), during recovery was very high (r=0.98). These results suggest that the PRR scale can be used by runners to determine the optimal duration of resting intervals between runs.

Adult↗
PubMed1999

Primary and secondary mechanisms of action of visible to near-IR radiation on cells.

Cytochrome c oxidase is discussed as a possible photoacceptor when cells are irradiated with monochromatic red to near-IR radiation. Four primary action mechanisms are reviewed: changes in the redox properties of the respiratory chain components following photoexcitation of their electronic states, generation of singlet oxygen, localized transient heating of absorbing chromophores, and increased superoxide anion production with subsequent increase in concentration of the product of its dismutation, H2O2. A cascade of reactions connected with alteration in cellular homeostasis parameters (pHi, [Cai], cAMP, Eh, [ATP] and some others) is considered as a photosignal transduction and amplification chain in a cell (secondary mechanisms).

Animals↗
PubMed1997

Ultrastructural changes in chondriome of human lymphocytes after irradiation with He-Ne laser: appearance of giant mitochondria.

The structure of mitochondria was studied after the irradiation of human lymphocytes with an He-Ne laser (wavelength, 632.8 nm; dose, 56 J m-2). Ultrathin sections of the lymphocytes were studied by electron microscopy 1 h after the irradiation. The irradiation resulted in a 20% increase (p = 0.95) in the number of mitochondrial profiles on the cell section without an increase in their total area. Three-dimensional reconstruction of mitochondria from ultrathin sections trough the whole lymphocyte showed that the number of mitochondria was reduced to 9-12 in the irradiated cells compared with 40-45 in the control cells. In the irradiated lymphocytes, 2-4 giant branching mitochondria were also observed among small discrete mitochondria.

Helium↗
PubMed1995

Irradiation with He-Ne laser increases ATP level in cells cultivated in vitro.

A monolayer of HeLa cells was irradiated with an He-Ne laser (632.8 nm, 100 J m-2, 10 s) and the amount of adenosine triphosphate (ATP) was measured by the luceferin-luciferase bioluminescent assay technique at different times (5-45 min) after irradiation. The amount of ATP in the log phase of cultured cells remained at the control level (0.79 +/- 0.09) x 10(-15) mol per cell) during the first 15 min after irradiation; it then increased sharply and, after reaching a maximum (170.8%) 20 min after irradiation, decreased slowly to the control level. The ability of monochromatic red light to induce an increase in the cellular ATP level was found to depend on the growth phase of the culture, being insignificant in the lag phase of cultured cells, increasing in the log phase of cultured cells and reaching a maximum (about 190%) in cells at the late logarithmic and early plateau phase.

Adenosine Triphosphate↗
PubMed1994

Two different mechanisms of low-intensity laser photobiological effects on Escherichia coli.

Bacterial suspensions in a phosphate buffer were irradiated at wavelengths lambda of 632.8, 1066 and 1286 nm, incubated in Hottinguer broth for 60 min and assayed for viability by the standard surface-plating technique. The difference between the number of viable cells in the irradiated culture and the control was termed growth stimulation. Irradiation of the bacteria with an He-Ne laser (632.8 nm) or semiconductor lasers at 1066 and 1286 nm at various intensities and irradiation times produced two maxima in the growth stimulation vs. dose curve. The first maximum, in all cases, occurred near 50 J m-2, and the reciprocity law was obeyed. The second maximum occurred at an irradiation time of 100 s irrespective of the particular radiation intensity, and the reciprocity law was not obeyed. It is assumed that two different mechanisms are responsible for these two maxima in the growth stimulation vs. dose curve.

Dose-Response Relationship, Radiation↗
PubMed1994

Irradiation with He--Ne laser can influence the cytotoxic response of HeLa cells to ionizing radiation.

A monolayer of HeLa cells in plateau-phase of growth was exposed to He--Ne laser radiation (632.8 nm, 100 J/m2) either 5, 60 or 180 min before gamma-irradiation (0.2-10 Gy, 6.75 Gy/min). In the case of a 5 min interval between the two types of irradiations the survival curve was practically identical to the survival curve of the cells after gamma-irradiation only. In the case of He--Ne laser exposure 60 min before gamma-irradiation with doses > 5 Gy, a fraction of more resistant cells was revealed: their Do was twice as high as the Do of the main population (3.6 and 1.7 Gy, respectively). A preexposure of cells to He--Ne laser (100 J/m2) 60 or 180 min before gamma-irradiation (5 Gy) also changed the shape of the growth curves as compared with gamma-irradiated cells (stimulation in exponential phase of growth). It is proposed that the preexposure of cells to He--Ne laser radiation activates, in a subpopulation of cells, processes which speed up the repair of gamma-radiation damage. The possibility that the described phenomenon is an adaptive response of cells is discussed.

Cell Division↗
PubMed1993

Changes in oxidative metabolism of murine spleen following laser and superluminous diode (660-950 nm) irradiation: effects of cellular composition and radiation parameters.

Chemiluminescence (CL) of splenocytes of A/Sn mice was recorded after irradiation of the cells with various individual laser an superluminous diode probes at wavelengths from 660 to 950 nm (pulse repetition rates varying from 4 to 5,000 Hz) and at various doses. Laser radiation was found to increase or suppress the spontaneous CL of splenocytes suspension, the amplitude and the sign of the effect depending on the cellular composition of the samples. Direct correlations between the effect of laser radiation (per cent in changes of CL when irradiated at 820 nm, 1.1 x 10(3) J/m2, 292 Hz) and per cent of plasmacytes (r = 0.743, P < 0.001), neutrophils (r = 0.650, P < 0.001) as well as myelocytes and metamyelocytes (r = 0.505, P < 0.01) were established. The correlation with per cent of lymphocytes (r = -0.590, P < 0.001) was found to be a reverse one. Dependence of the irradiation effects on dose, pulse repetition rate, and wavelength are presented.

Aging↗
PubMed1992

He-Ne laser irradiation of single identified neurons.

Silent (LPa2 and LPa3) and spontaneously active (V3, V5, V17) neurons of subesophageal ganglia of Helix pomatia were irradiated via a 125-mm fiber probe with a 10-mW He-Ne laser (lambda = 632.8 nm), and the rate of membrane depolarization, duration of latent period, and probability of spike activity were measured as the functions of light intensity. It was found that silent neurons can not be activated by He-Ne laser irradiation. When the spontaneously active neurons generating spikes every 7-10 min were irradiated in between their spontaneous spikes, the depolarization of membrane and generation of action potentials occurred as a function of light intensity, I. The probability of spike generation increased until the intensity reached 1 W/cm2, and when I = 4 W/cm2 was equal to 1. The depolarization of the membrane had a threshold at I = 0.1 W/cm2, then increased with increasing the intensity, and reached a plateau at I = 0.7 W/cm2 (depolarization rate 0.18 mV/s). Duration of the latent period decreased from 28 s to 17 s when the intensity was increased from 0.05 to 0.3 W/cm2. Further increase of the light intensity, from 0.3 to 1.5 W/cm2, caused a less pronounced change in the duration of the latent period (e.g., latent period equal to 11 s at I = 1.5 W/cm2).

Action Potentials↗
PubMed1991

Action of low-intensity laser radiation on Escherichia coli.

The review deals with quantitative laws of monochromatic visible light action on the cellular level, as well as with the primary photoacceptors and possible light signal transduction chains in bacterial cell Escherichia coli WP2 trp-. Experiments described in this paper are a part of experimental work performed for explaining the molecular mechanism of low-intensity laser therapy. The existence of certain parameters of light (dose, intensity, pulse repetition rate, monochromaticity within the absorbtion bandwidth of biomolecules) for stimulation of E. coli WP2 metabolism has been established. The necessity for a certain physiological state of bacteria cells sensitive to irradiation has been shown. The sensitivity of bacteria to irradiation with monochromatic visible light has been proposed to be a delta pH-dependent genetic process.

Escherichia coli↗
PubMed1989

Role of primary photoacceptors in low-power laser effects: action of He-Ne laser radiation on bacteriophage T4-Escherichia coli interaction.

The effect of He-Ne laser radiation (lambda = 632.8 nm) on bacteriophage T4-Escherichia coli WP2 interactions was studied. Irradiation of bacteria having respiratory chain components as primary photoacceptors accelerated their division in a dose-dependent manner, but irradiation had no effect on the properties of the phage (measured as its ability to infect host cells). At the same time, exposure of bacteria to stimulating doses of He-Ne laser radiation (from 10(3) to 6 x 10(4) J/m2) increased their ability to promote the growth of unexposed phages. These results clearly indicate that low-power laser effects require primary photoacceptors (phage contains no chromophores for red light).

Escherichia coli↗
PubMed1989

Photobiology of low-power laser effects.

Quantitative studies have been performed to determine the action of low-intensity visible monochromatic light on various cells (E. coli, yeasts, HeLa, Chinese hamster fibroblasts and human lymphocytes); also irradiation conditions (wavelength, dose and intensity) conducive to vital activity stimulation have been examined. Respiratory chain components are discussed as primary photoacceptors. The possible ways for photosignal transduction and amplification are discussed. It is proposed that enhanced wound healing due to irradiation with low-intensity visible laser light (He-Cd, He-Ne and semiconductor lasers) is due to the increasing proliferation of cells.

Animals↗