Photomodulation of glutamate dehydrogenase properties by red light

Functional characterization of the oxidative capacity of mitochondria and glycolytic assessment in benthic aquatic organisms

The metabolism of benthic aquatic invertebrates, populating transitional water ecosystems, is influenced by both physiological and environmental factors, thus involving an adjustment of physiological processes which has a metabolic cost. In order to discover changes in metabolic pathways in response to specific factors, it's firstly necessary characterizing the principal cellular metabolic activities of the small benthic aquatic organisms. We approach here the bioenergetic state issue of two benthic organisms, i.e. Lekanesphaera monodi and Gammarus insensibilis, evidencing that no apparent and statistically significative differences between them in aerobic as well in glycolytic capacities are detected, except for COX activity.

Absorption of monochromatic and narrow band radiation in the visible and near IR by both mitochondrial and non-mitochondrial photoacceptors results in photobiomodulation

In addition to the major functions performed by in the cell, mitochondria play a major role in cell-light interaction. Accordingly it is generally accepted that mitochondria are crucial in cell photobiomodulation; however a variety of biomolecules themselves proved to be targets of light irradiation. We describe whether and how mitochondria can interact with monochromatic and narrow band radiation in the red and near IR optical regions with dissection of both structural and functional effects likely leading to photobiostimulation. Moreover we also report that a variety of biomolecules localized in mitochondria and/or in other cell compartments including cytochrome c oxidase, some proteins, nucleic acids and adenine nucleotides are light sensitive with major modifications in their biochemistry. All together the reported investigations show that the elucidation of the mechanism of the light interaction with biological targets still remains to be completed, this needing further research, however the light sensitivity of a variety of molecules strongly suggests that photobiomodulation could be used in both in photomedicine and in biotechnology.

Effect of GaAlAs laser irradiation on enzyme activity

OBJECTIVE

The aim of this study was to determine the influence of laser irradiation on enzyme activity.

BACKGROUND DATA

Enzymes are catalysts of extraordinary efficiency, able to accelerate reactions by manifold. Enzyme laser light activation is currently a fast-growing field and a large number of studies have been produced.

MATERIALS AND METHODS

Liquid CNPG amylase and control serum (Qualitrol 1H) were used in the experiments. Laboratory analysis of alpha-amylase was performed on two sample groups: (i) E + S and (ii) E + S + L, in six repetitions per irradiation dose. Group 2 was irradiated with gallium-aluminum-arsenide (GaAlAs) 904 nm at doses of 0.01, 0.1, 0.5, and 1 J/cm(2). Enzyme activity was read using a spectrophotometer equipped with a thermostatic chamber capable of precise absorbance measurement at 405 nm.

RESULTS

The results were analyzed with the Student's t-test, and the percentage of enzyme activity was determined. Photomodulation of alpha-amylase activity by GaAlAs laser was analyzed following irradiation with different doses. Irradiation doses from 0.01 to 1 J/cm(2) led to differences in enzyme activity: 0.01 J/cm(2) (0.10%), 0.1 J/cm(2) (13.44%), 0.5 J/cm(2) (12.57%), and 1 J/cm(2) (-6.10%).

CONCLUSION

Irradiation doses of 0.1 J/cm(2) and 0.5 J/cm(2) led to statistically significant increases in enzyme activity in comparison to the control. The similar curves of the effects of temperature and pH on enzymatic activity observed in this study suggest that laser irradiation also possess an optimum dose to modulate the enzymatic activity. That is, enzymes have an optimum laser dose (or range) at which their activity is maximal, whereas at higher or lower doses activity decreases.

Caspase-dependent alteration of the ADP/ATP translocator triggers the mitochondrial permeability transition which is not required for the low-potassium-dependent apoptosis of cerebellar granule cells

We investigated ADP/ATP exchange mediated by the adenine nucleotide translocator and opening of the mitochondrial permeability transition pore in homogenates from cerebellar granule cells en route to apoptosis induced by low potassium. We showed that, in the first 3 h of apoptosis, when maximum cytochrome c release had already occurred, adenine nucleotide translocator function was impaired owing to the action of reactive oxygen species, but no permeability transition pore opening occurred. Over 3-8 h of apoptosis, the permeability transition pore progressively opened, owing to caspase action, and further ADP/ATP translocator impairment occurred. The kinetics of transport and permeability transition pore opening were inversely correlated, both in the absence and presence of inhibitors of antioxidant and proteolytic systems. We conclude that, en route to apoptosis, alteration of the adenine nucleotide translocator occurs, resulting in permeability transition pore opening. This process depends on the action of caspase on pore component(s) other than the ADP/ATP translocator, because no change in either amount or molecular weight of the latter protein was noted during apoptosis, as measured by western blotting. Cell death occurs via apoptosis in the presence of cyclosporin A, the permeability transition pore inhibitor, thus showing that permeability transition pore opening, not needed for cytochrome c release, is also unnecessary for apoptosis to occur.

The electric field induced by light can explain cellular responses to electromagnetic energy: a hypothesis of mechanism

When cells are irradiated with visible and near-infrared wavelengths a variety of stimulatory effects are observed in their metabolism. To explain the observed light effects, researchers try to identify the chromophores that are involved in the processes. However, the mechanism of light absorption by a chromophore does not explain many of the experimental observations and therefore the primary mechanism for cellular light responses remains unproven. In addition to the ability of photons to produce electronic excitation in chromophores, light induces a wave-like alternating electric field in a medium that is able to interact with polar structures and produce dipole transitions. These dipole transitions are analyzed in the present article at different cellular and biochemical levels, leading to the proposal that the primary mechanism for the observed light effects is related to the light-induced electric field.

Biophotons, microtubules and CNS, is our brain a “Holographic computer”?

Several experiments show that there is a cell to cell communication by light in different cell types. This article describes theoretical mechanisms and subcellular structures that could be involved in this phenomenon. Special consideration is given to the nervous system, since it would have excellent conditions for such mechanisms. Neurons are large colourless cells with wide arborisations, have an active metabolism generating photons, contain little pigment, and have a prominent cytoskeleton consisting of hollow microtubules. As brain and spinal cord are protected from environmental light by bone and connective tissue, the signal to noise ratio should be high for photons as signal. Fluorescent and absorbing substances should interfere with such a communication system. Of all biogenic amines nature has chosen the ones with the strongest fluorescence as neurotransmitters for mood reactions: serotonin, dopamine and norepinephrine. If these mechanisms are of relevance our brain would have to be looked upon as a "holographic computer".

Helium-Neon laser irradiation of hepatocytes can trigger increase of the mitochondrial membrane potential and can stimulate c-fos expression in a Ca2+-dependent manner

BACKGROUND AND OBJECTIVE

To gain some insight into the photostimulation of isolated hepatocytes irradiated with Helium-Neon (He-Ne) laser light certain biochemical events were studied with respect to two mechanisms: i) the direct light dependent activation of certain biochemical events investigated in intact cells and isolated mitochondria, ii) the indirect stimulation of processes per se light independent.

STUDY DESIGNS/MATERIALS AND METHODS

Irradiation of either isolated hepatocytes or isolated rat liver mitochondria was carried out with He-Ne laser (wavelength, 632.8 nm; fluence, 0.24 J cm-2; fluence rate, 12 mW cm-2). Changes in mitochondrial membrane potential in isolated hepatocytes were monitored using the cationic probe safranine. The c-fos expression was studied by Northern blot and immunoblot analysis.

RESULTS

As a result of irradiation, increase of the mitochondrial membrane potential was found to occur in irradiated hepatocytes both in the presence or in the absence of CaCl2. The hyperpolarization of the mitochondrial membrane is assumed to cause an increase in mitochondrial Ca2+ uptake that was measured in isolated mitochondria. Finally, an increase in c-fos expression was found in irradiated hepatocytes when incubated in the presence of CaCl2.

CONCLUSION

This paper gives additional information on the mechanism by which He-Ne laser light, either directly or in a cascade-like effect dependent on increase in cell Ca2+, can cause cell stimulation.

Ultrastructure and reproduction behaviour of single CHO-K1 cells exposed to near infrared femtosecond laser pulses

In the present work, the authors investigated ultrastructural changes as well as the reproduction behaviour of preselected single CHO-K1 cells exposed to 170 femtosecond laser pulses at different power output levels in comparison with cells outside the illumination volume. The ultrashort laser pulses were provided by an 80 MHz Ti:sapphire laser at 780 nm. The cells were scanned ten times with a scan rate of 1/16 s(-1). Single CHO-K1 cells exposed to low mean power of 2 mW revealed no significant changes in ultrastructure after laser exposure. In some cases, changes of mitochondria with slight disordering of cristae were found. Cytoplasm was filled with vesicles that seemed to be released from Golgi stacks. Cells irradiated with higher powers demonstrated more dramatic changes in ultrastructure. A considerable number of swollen mitochondria in conjunction with loss of cristae was observed. The main event of mitochondrial changes was the formation of electron dense bodies in the mitochondrial matrix. In addition, lumen of endoplasmatic reticulum was enlarged. Highest applied mean laser power of 12.5 mW lead to complete destruction of mitochondria and their transformation to electron dense structures containing membrane material. Compared with cell targets irradiated with 2 mW mean power, the release of vesicles from Golgi stacks seemed to be rather moderate. Cells localised outside the laser beam revealed no ultrastructural changes. Low mean laser power at 2 mW was unable to impair the reproduction behaviour of CHO-K1 cells. At higher laser power output levels, CHO-K1 cells started to delay cell division. At 12.5 mW, no cell division occurred. The obtained results may be helpful in recommending parameters for safe femtosecond laser microscopy of living specimens.

Helium-neon laser irradiation is not a stressful treatment: a study on heat-shock protein (HSP70) level

BACKGROUND AND OBJECTIVE

Helium-neon (He-Ne) laser irradiation has been clinically used to reduce chemotherapy-induced mucositis. This work was designed to find out if this treatment is stressful at the cellular level by studying its effects on the level of the stress-inducible heat shock proteins.

STUDY DESIGN/MATERIALS AND METHODS

Human desmodontal and mouse L929 fibroblasts were irradiated using a 60 mW laser by a single application of 1.5 and 3J/cm2 in continuous mode. Heat shock protein level was studied by gel electrophoresis and Western blotting using monoclonal antibodies.

RESULTS

He-Ne treatment does not induce heat shock protein synthesis in human desmodontal nor in mouse fibroblasts at the energy densities used in this study.

CONCLUSIONS

These results indicate that the treatment is not stressful at the cellular level.

Changes in calcium transport in mammalian sperm mitochondria and plasma membranes caused by 780 nm irradiation

BACKGROUND AND OBJECTIVE

Regulation of intracellular Ca2+ concentrations are very important in control of sperm motility and acrosome reaction. It was shown previously that low-power lasers in the visible and near-infrared range alter Ca2+ uptake by sperm cells. In the present work the effect of a 780 nm diode laser on Ca2+ uptake by sperm mitochondria and isolated plasma membrane vesicles is investigated.

STUDY DESIGN/MATERIALS AND METHODS

Digitonin-treated spermatozoa and plasma membrane vesicles were irradiated with a 780-nm diode laser at various powers and energy doses, and Ca2+ uptake was measured by the filtration method.

RESULTS

It was found that 780-nm irradiation inhibits Ca2+ uptake by the mitochondria but stimulates Ca2+ binding by sperm plasma membrane vesicles. The effect of light on Ca2+ uptake by plasma membrane vesicles in the absence of ATP was much larger than that measured in the presence of ATP. Addition of Ca2+ ionophore decreased the Ca2+ uptake by the irradiated membranes in the presence of ATP but enhanced it significantly in the absence of ATP.

CONCLUSION

780 nm light inhibits Ca2+ uptake by sperm mitochondria and enhances Ca2+ binding to sperm plasma membranes.

Helium-neon laser preirradiation induces protection against UVC radiation in wild-type E. coli strain K12AB1157

We have observed that preirradiation with a helium-neon laser (632.8 nm) induces protection against UVC radiation in wild-type E. coli strain K12AB1157. The magnitude of protection was found to depend on the helium-neon laser irradiance, exposure time, and period of incubation between helium-neon laser exposure and subsequent UVC irradiation. The optimum values for dose, irradiance and interval between the two exposures were found to be 7 kJ/m(2), 100 W/m(2) and 1 h, respectively. The possible involvement of singlet oxygen in the helium-neon laser-induced protection is also discussed.

Studies on the in vitro inversion of flurbiprofen

This paper reports in vitro studies on the metabolic inversion of flurbiprofen (FL), an arylpropionic acid antiinflammatory agent (2-APA). The inversion was studied with both rac-FL and R-FL, by incubation with rat hepatic microsomes, in the presence of either CoASH and ATP or NADPH. The two isomers of the drug were separated as their (+)-(R)-1-phenylethylamides by direct phase high-performance liquid chromatography on a silica gel column with an achiral mobile phase. The inversion was more pronounced in the presence of CoASH and ATP for both the racemate and the R-isomer, which supports the key role of CoA thioesters in the metabolic inversion of profens. The inversion observed in the presence of NADPH suggests that, when the incubation is run with hepatic microsomes, a CYP450-mediated pathway is also active. In order to get more insight into the CYP450-mediated inversion pathway, we studied the effect of irradiating microsomes with a low dose of He-Ne laser radiation (0.2 J). Such irradiation caused a significant increase in inversion at all times studied and normalized the anomalous value of inversion observed at 15 min in this pathway.

Increase in cytosolic and mitochondrial protein synthesis in rat hepatocytes irradiated in vitro by He-Ne laser

In order to gain an insight into the mechanism of cell photostimulation by laser light, protein synthesis was measured in hepatocytes irradiated with a low-power, continuous-wave He-Ne laser (fluence, 0.24 J cm(-2); fluence rate, 7 and 12 mW cm(-2)). As a result of irradiation, the rate and amount of 35S-methionine incorporated into newly synthesized proteins increased, as demonstrated by gel electrophoresis and quantitative analysis of labelled protein bands. The stimulation of protein synthesis was fluence dependent, with a maximum stimulation at 0.24 J cm(-2) for both fluence rates (12 and 7 mW cm(-2)). Both cytosolic and mitochondrial protein synthesis increased as a result of irradiation, as demonstrated by the measurement of hepatocytes previously treated with chloramphenicol and cycloheximide respectively. An initial investigation showed that stimulation of protein synthesis also occurred in hepatocytes irradiated with a non-coherent radiation source (fluence, 0.24 J cm(-2)).

Determination of glutamate decarboxylase by high-performance liquid chromatography

An improved method for the determination of glutamate decarboxylase (GAD) activity is described. The enzyme was evaluated by incubation with glutamic acid (L-Glu) in the presence of pyridoxal 5'-phosphate (PLP): the gamma-aminobutyric acid (GABA) formed was derivatized to PTC-GABA; the latter was subsequently separated and assayed by isocratic HPLC (LiChrospher RP-18 column; isocratic elution with pH 5.8 acetate buffer in acetonitrile-water) with UV absorbance detection at 254 nm. The method described is a sensitive, reproducible and specific assay useful for following variations of GAD activity in vitro; this assay was subsequently used for the evaluation of GAD activity variations after irradiation with low doses of He-Ne laser radiation.

Effects of low-power 632 nm radiation (HeNe laser) on a human cell line: influence on adenylnucleotides and cytoskeletal structures

HeNe (632 nm) irradiation (5, 15 and 30 min) of an embryonal human cell line (EUE) was used to study the short-term effects on energy charge and the rapid, energy-dependent, remodelling processes of cytoskeletal and adhesion structures. The adenosine triphosphate (ATP) concentration, tested by luminometric and high performance liquid chromatography (HPLC) procedures, is constant after 15 and 30 min of HeNe treatment; the lower phosphorylated nucleotides, i.e. adenosine diphosphate (ADP) and adenosine monophosphate (AMP), change after 30 min in opposite directions: the ADP concentration decreases by 39% whilst that of AMP increases about sixfold. The adenylate energy charge (AEC) decreases by 21.7% in treated EUE cells (AEC = 0.65) in comparison with untreated EUE cells (AEC = 0.83). In HeNe-treated cells, the remodelling of cytoskeletal and adhesion molecules becomes evident after 15 min of treatment. The following events are important: (1) modification of stress fibre assembly and increase in vinculin-containing adhesion plaques; (2) assembly and bundling of intermediate filaments; (3) increase in laminin and L-cell adhesion molecules (L-CAM) expression. The lowered energy charge in irradiated cells is related to the increase in AMP production at the expense of ADP. ATP is dynamically constant despite its requirement in short-time remodelling processes of the cytoskeletal network which are enhanced in irradiated cells.