Red and near-infrared light evokes Ca2+ influx, endoplasmic reticulum release and membrane depolarization in neurons and cancer cells.

Low level light therapy uses light of specific wavelengths in red and near-infrared spectral range to treat various pathological conditions. This light is able to modulate biochemical cascade reactions in cells that can have important health implications. In this study, the effect of low intensity light at 650, 808 and 1064 nm on neurons and two types of cancer cells (neuroblastoma and HeLa) is reported, with focus on the photoinduced change of intracellular level of Ca2+ ions and corresponding signaling pathways. The obtained results show that 650 and 808 nm light promotes intracellular Ca2+ elevation regardless of cell type, but with different dynamics due to the specificities of Ca2+ regulation in neurons and cancer cells. Two origins responsible for Ca2+ elevation are determined to be: influx of exogenous Ca2+ ions into cells and Ca2+ release from endoplasmic reticulum. Our investigation of the related cellular processes shows that light-induced membrane depolarization is distinctly involved in the mechanism of Ca2+ influx. Ca2+ release from endoplasmic reticulum activated by reactive oxygen species generation is considered as a possible light-dependent signaling pathway. In contrast to the irradiation with 650 and 808 nm light, no effects are observed under 1064 nm irradiation. We believe that the obtained insights are of high significance and can be useful for the development of drug-free phototherapy.

Vitamin D status is seasonally stable in northern European dogs.

BACKGROUND: Numerous studies in veterinary species have recently linked vitamin D status with nonskeletal health disorders. Previous studies have indicated that dogs cannot produce endogenous vitamin D via cutaneous production and rely solely on dietary intake of vitamin D. The seasonal variation of vitamin D seen in humans due to changes in ultraviolet (UV) exposure, therefore, is unlikely to be replicated in these animals. OBJECTIVES: The objective of this study was to investigate the natural variation in 25-hydroxyvitamin-D concentrations in dogs subject to seasonal UV exposure. METHODS: This longitudinal study followed 18 healthy dogs fed a standardized diet over 1 year, with blood samples obtained monthly. Two key vitamin D metabolites, 25-hydroxyvitamin-D2 and 25-hydroxyvitamin-D3 , were assessed by liquid chromatography-tandem mass spectrometry in serum samples. Various other biochemical parameters were also measured. Seasonality was assessed using cosinor statistical analysis. RESULTS: Although the dogs were subject to seasonally varying UV radiation, 25-hydroxyvitamin-D and related biomarkers (including calcium and parathyroid hormone) remained stable over time and did not follow a seasonal pattern. 25-hydroxyvitamin-D was not positively correlated with exposure to UV radiation. Nonetheless, variation in 25-hydroxyvitamin-D concentrations between individual dogs was detected. CONCLUSIONS: Given the standardization of diet, we concluded that the seasonal stability of 25-hydroxyvitamin-D concentration (vitamin D status) was likely a direct result of lack of cutaneous vitamin D production in this species and highlights the importance of dietary intake. The variation in 25-hydroxyvitamin-D concentration between animals warrants further investigation.

Intrinsic attenuation of post-irradiation calcium and ER stress imparts significant radioprotection to lepidopteran insect cells.

Sf9 lepidopteran insect cells are 100-200 times more radioresistant than mammalian cells. This distinctive feature thus makes them suitable for studies exploring radioprotective molecular mechanisms. It has been established from previous studies of our group that downstream mitochondrial apoptotic signaling pathways in Sf9 cells are quite similar to mammalian cells, implicating the upstream signaling pathways in their extensive radioresistance. In the present study, intracellular and mitochondrial calcium levels remained unaltered in Sf9 cells in response to radiation, in sharp contrast to human (HEK293T) cells. The isolated mitochondria from Sf9 cells exhibited nearly 1.5 times greater calcium retention capacity than mammalian cells, highlighting their inherent stress resilience. Importantly, UPR/ER stress marker proteins (p-eIF2α, GRP4 and SERCA) remained unaltered by radiation and suggested highly attenuated ER and calcium stress. Lack of SERCA induction further corroborates the lack of radiation-induced calcium mobilization in these cells. The expression of CaMKII, an important effector molecule of calcium signaling, did not alter in response to radiation. Inhibiting CaMKII by KN-93 or suppressing CaM by siRNA failed to alter Sf9 cells response to radiation and suggests CaM-CaMKII independent radiation signaling. Therefore, this study suggests that attenuated calcium signaling/ER stress is an important determinant of lepidopteran cell radioresistance.

Electric pulses: a flexible tool to manipulate cytosolic calcium concentrations and generate spontaneous-like calcium oscillations in mesenchymal stem cells.

Human adipose mesenchymal stem cells (haMSCs) are multipotent adult stem cells of great interest in regenerative medicine or oncology. They present spontaneous calcium oscillations related to cell cycle progression or differentiation but the correlation between these events is still unclear. Indeed, it is difficult to mimic haMSCs spontaneous calcium oscillations with chemical means. Pulsed electric fields (PEFs) can permeabilise plasma and/or organelles membranes depending on the applied pulses and therefore generate cytosolic calcium peaks by recruiting calcium from the external medium or from internal stores. We show that it is possible to mimic haMSCs spontaneous calcium oscillations (same amplitude, duration and shape) using 100 µs PEFs or 10 ns PEFs. We propose a model that explains the experimental situations reported. PEFs can therefore be a flexible tool to manipulate cytosolic calcium concentrations. This tool, that can be switched on and off instantaneously, contrary to chemicals agents, can be very useful to investigate the role of calcium oscillations in cell physiology and/or to manipulate cell fate.

Effects of electromagnetic field exposure on conduction and concentration of voltage gated calcium channels: A Brownian dynamics study.

A three-dimensional Brownian Dynamics (BD) in combination with electrostatic calculations is employed to specifically study the effects of radiation of high frequency electromagnetic fields on the conduction and concentration profile of calcium ions inside the voltage-gated calcium channels. The electrostatic calculations are performed using COMSOL Multiphysics by considering dielectric interfaces effectively. The simulations are performed for different frequencies and intensities. The simulation results show the variations of conductance, average number of ions and the concentration profiles of ions inside the channels in response to high frequency radiation. The ionic current inside the channel increases in response to high frequency electromagnetic field radiation, and the concentration profiles show that the residency of ions in the channel decreases accordingly.

Sub-100 ps coincidence time resolution for positron emission tomography with LSO:Ce codoped with Ca.

The coincidence time resolution (CTR) becomes a key parameter of 511 keV gamma detection in time of flight positron emission tomography (TOF-PET). This is because additional information obtained through timing leads to a better noise suppression and therefore a better signal to noise ratio in the reconstructed image. In this paper we present the results of CTR measurements on two different SiPM technologies from FBK coupled to LSO:Ce codoped 0.4%Ca crystals. We compare the measurements performed at two separate test setups, i.e. at CERN and at FBK, showing that the obtained results agree within a few percent. We achieve a best CTR value of 85 ± 4 ps FWHM for 2 × 2 × 3 mm(3) LSO:Ce codoped 0.4%Ca crystals, thus breaking the 100 ps barrier with scintillators similar to LSO:Ce or LYSO:Ce. We also demonstrate that a CTR of 140 ± 5 ps can be achieved for longer 2 × 2 × 20 mm(3) crystals, which can readily be implemented in the current generation PET systems to achieve the desired increase in the signal to noise ratio.

The effects of UV light on calcium metabolism in ball pythons (Python regius).

Despite the popularity of keeping snakes in captivity, there has been limited investigation into the effects of UV radiation on vitamin D levels in snakes. The aim of this study was to investigate the effects of UV-b radiation on plasma 25-hydroxyvitamin D3 levels and ionised calcium concentrations in ball pythons (Python regius). Blood samples were taken from 14 ball pythons, which had never been exposed to UV-b light, to obtain baseline 25-hydroxyvitamin D3 levels and ionised calcium concentrations. Blood samples were then taken again from the same snakes 70 days later after one group (Group 1, n=6 females) were exposed to UV-b radiation daily, and the other group (Group 2, n=5 males and 3 females) were exposed to no UV-b radiation. Mean±sd 25-hydroxyvitamin D3 levels on day 0 in Group 1 were 197±35 nmol/l, and on day 70 were 203.5±13.8 nmol/l. Mean±sd 25-hydroxyvitamin D3 levels in Group 2 on day 0 were 77.7±41.5 nmol/l, and on day 70 were 83.0±41.9 nmol/l. Mean±sd ionised calcium levels at day 0 were 1.84±0.05 mmol/l for Group 1, and on day 70 were 1.78±0.07 mmol/l. Mean±sd ionised calcium levels at day 0 were 1.79±0.07 mmol/l for Group 2, and on day 70 were 1.81±0.05 mmol/l. No association was demonstrated between exposure to UV-b radiation and plasma 25-hydroxyvitamin D3 and ionised calcium concentrations. These results may provide baseline parameters for future studies in this and other snake species to determine ability to utilise UV-b light for vitamin D production.

Low-power laser irradiation promotes the proliferation and osteogenic differentiation of human periodontal ligament cells via cyclic adenosine monophosphate.

Retaining or improving periodontal ligament (PDL) function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation (LPLI) on the proliferation and osteogenic differentiation of human PDL (hPDL) cells. Cultured hPDL cells were irradiated (660 nm) daily with doses of 0, 1, 2 or 4 J⋅cm(-2). Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase (ALP) activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR). Our data showed that LPLI at a dose of 2 J⋅cm(-2) significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J⋅cm(-2) showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate (cAMP) is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.

[The effect of weak low-frequency magnetic fields on the intracellular calcium-dependent proteinases of fish].

The in vivo and in vitro effects of weak, low-frequency magnetic fields with resonance parameters for calcium ions upon intracellular calcium-dependent proteinases (calpains) in the crucian carp (Carassius carassius (L.) and roach (Rutilus rutilus (L.) were studied. It has been revealed that the impact of a weak low-frequency magnetic field leads to considerable decrease in the activity of calpains in the fish skeletal muscles and brain.

Role of melatonin on electromagnetic radiation-induced oxidative stress and Ca2+ signaling molecular pathways in breast cancer.

AIMS: Exposure to electromagnetic radiation (EMR) may increase breast cancer risk by inducing oxidative stress and suppressing the production of melatonin. Aim of the present review is to discuss the mechanisms and risk factors of EMR and oxidative stress-induced breast cancer, to summarize the controlled studies evaluating measures for prevention, and to conclude with evidence-based strategies for prevention. MATERIALS: Review of the relevant literature and results from our recent basic studies, as well as critical analyses of published systematic reviews were obtained from the Pubmed and the Science Citation Index. RESULTS: It has been proposed that chronic exposure to EMR may increase the risk of breast cancer by suppressing the production of melatonin; this suppression may affect the development of breast cancer either by increasing levels of circulation of estrogen or through over production of free oxygen radicals. Most epidemiological studies have also indicated overall effect of EMR exposure in premenopausal women, particularly for estrogen receptor positive breast tumors. Enhanced voltage-dependent Ca(2+) current and impaired inhibitory G-protein function, and derangement of intracellular organelles with a Ca(2+) buffering effect, such as endoplasmic reticulum and mitochondria have been also shown to contribute to disturbed Ca(2+) signaling in breast cancer. CONCLUSION: Melatonin may modulate breast cancer through modulation of enhanced oxidative stress and Ca(2+) influx in cell lines. However, there is not enough evidence on increased risk of breast cancer related to EMR exposure.

Intracellular Ca(2+) levels in rat ventricle cells exposed to extremely low frequency magnetic field.

OBJECTIVE: Electromagnetic fields can affect intracellular Ca(2+) levels. The aim of this study was to determine the changes intracellular Ca(2+) concentration in cardiac ventricle cells of rats exposed to 0.25 mT (2.5 Gauss) magnetic field. METHODS: Forty-five male rats were introduced to this study. The rats were divided into three groups: control, sham, and experiment. The experimental group was exposed to 0.25 mT extremely low frequency (ELF) magnetic field for 14 days, 3 h/day. The sham group was treated like the experimental group, except for elf-magnetic field exposure. The control group was not subjected to anything and differed from the experimental group and sham group. In the end of experiment, rats were sacrificed, cardiac tissue was removed, and these were fixed in 10% neutral formalin. Then, ventricular cells were stained by Alizarin red staining method. RESULTS: In the light microscopic examinations of control groups, in myofibril structures between groups, changes were not observed. In myofibril regions of the experimental group compared to other groups, increased heterogen Ca(2+) accumulations were found. CONCLUSION: ELF magnetic fields are used in daily life. The results of this study show that intracellular Ca(2+) accumulation in cardiac ventricles can increase in rats exposed to ELF magnetic field.

Intracellular calcium transients evoked by pulsed infrared radiation in neonatal cardiomyocytes.

Neonatal rat ventricular cardiomyocytes were used to investigate mechanisms underlying transient changes in intracellular free Ca2+ concentration ([Ca2+]i) evoked by pulsed infrared radiation (IR, 1862 nm). Fluorescence confocal microscopy revealed IR-evoked [Ca2+]i events with each IR pulse (3-4 ms pulse⁻¹, 9.1-11.6 J cm⁻² pulse⁻¹). IR-evoked [Ca2+]i events were distinct from the relatively large spontaneous [Ca2+]i transients, with IR-evoked events exhibiting smaller amplitudes (0.88 ΔF/F0 vs. 1.99 ΔF/F0) and shorter time constants (τ =0.64 s vs. 1.19 s, respectively). Both IR-evoked [Ca2+]i events and spontaneous [Ca2+]i transients could be entrained by the IR pulse (0.2-1 pulse s⁻¹), provided the IR dose was sufficient and the radiation was applied directly to the cell. Examination of IR-evoked events during peak spontaneous [Ca2+]i periods revealed a rapid drop in [Ca2+]i, often restoring the baseline [Ca2+]i concentration, followed by a transient increase in [Ca2+]i.Cardiomyocytes were challenged with pharmacological agents to examine potential contributors to the IR-evoked [Ca2+]i events. Three compounds proved to be the most potent, reversible inhibitors: (1) CGP-37157 (20 µM, n =12), an inhibitor of the mitochondrial Na+/Ca2+ exchanger (mNCX), (2) Ruthenium Red (40 µM, n =13), an inhibitor of the mitochondrial Ca2+ uniporter (mCU), and (3) 2-aminoethoxydiphenylborane (10 µM, n =6), an IP3 channel antagonist. Ryanodine blocked the spontaneous [Ca2+]i transients but did not alter the IR-evoked events in the same cells. This pharmacological array implicates mitochondria as the major intracellular store of Ca2+ involved in IR-evoked responses reported here. Results support the hypothesis that 1862 nm pulsed IR modulates mitochondrial Ca2+ transport primarily through actions on mCU and mNCX.

Effects of zinc phthalocyanine tetrasulfonate-based photodynamic therapy on rat brain isolated mitochondria.

PDT has been used in the treatment of malignant brain tumors for the last 2 decades. It is based on the interaction of a photosensitizer (PS) and light of an appropriate wavelength, with generation of oxygen species, mainly singlet oxygen. Brain is particularly susceptible to oxidative stress; therefore the study of PDT effects on cerebral mitochondria might provide mechanistic insights into the action of the therapy, contributing to its optimization. In the present study, we addressed the mitochondrial toxicity of the second generation PS, zinc phthalocyanine tetrasulfonate (ZnPcS4), on rat brain isolated mitochondria, by investigating both intrinsic toxicity and photodynamic action. At higher concentrations (15 and 25 microM/mg protein) ZnPcS4 caused (a) inhibition of state-3 respiration and (b) decrease of RCR and ADP/O. Electrochemical potential, state-4 respiration and Ca2+ retention capacity were not affected. Cytochrome c release was not observed. Coupled with 600 or 1800 mJ/cm2 laser irradiation, ZnPcS4 (5 microM/mg protein) caused more intense effects on state 3, RCR and ADP/O; moreover state-4 respiration and membrane potential were affected. Besides that, Ca2+ and cytochrome c release were induced. Cyclosporine A (CsA) decreased Ca2+ release and ameliorated the electrochemical potential, suggesting that membrane permeability transition (MPT) might be involved in the photodynamic effect. The low intrinsic toxicity and the high photodynamic effect on rat brain mitochondria induced by ZnPcS4, allied to its improved photophysical properties, might indicate its potential for the treatment of malignant brain tumors.

Effect of same-dose single or dual field irradiation on damage to miniature pig parotid glands.

AIM: To evaluate the effect of single or dual field irradiation (IR) with the same dose on damage to miniature pig parotid glands. METHODOLOGY: Sixteen miniature pigs were divided into two IR groups (n=6) and a control group (n=4). The irradiation groups were subjected to 20 Gy X-radiation to one parotid gland using single-field or dual-field modality by linear accelerator. The dose-volume distributions between two IR groups were compared. Saliva from parotid glands and blood were collected at 0, 4, 8 and 16 weeks after irradiation. Parotid glands were removed at 16 weeks to evaluate tissue morphology. RESULTS: The irradiation dose volume distributions were significantly different between single and dual field irradiation groups (t=4.177, P=0.002), although dose volume histogramin (DVH) indicated the equal maximal dose in parotid glands. Saliva flow rates from IR side decreased dramatically at all time points in IR groups, especially in dual field irradiation group. The radiation caused changes of white blood cell count in blood, lactate dehydrogenase and amylase in serum, calcium, potassium and amylase in saliva. Morphologically, more severe radiation damage was found in irradiated parotid glands from dual field irradiation group than that from single field irradiation group. CONCLUSION: Data from this large animal model demonstrated that the radiation damage from the dual field irradiation was more severe than that of the single field irradiation at the same dose, suggesting that dose-volume distribution is an important factor in evaluation of the radiobiology of parotid glands.

Static magnetic field expose enhances neurotransmission in crayfish nervous system.

PURPOSE: To investigate the effects of static magnetic field (SMF) exposure on the synaptic transmission in a tail-flip circuit of crayfish. MATERIALS AND METHODS: An O-shaped permanent magnet (35 mT intensity) was placed under the isolated nerve cord of crayfish to provide static magnetic field exposure. Using electrophysiological methods, the excitatory post synaptic potential (EPSP) before and after field exposure in the lateral giant interneuron were measured and compared. RESULTS: The EPSP produced via electrical and chemical synapses in the lateral giant neuron were enhanced after 30 min of SMF exposure (8.08 mT). Perfusion of field-exposed crayfish bath solution or preloading of Ca(2+) chelator and intracellular Ca(2+) release blocker failed to observe the SMF-induced enhancement on EPSP. CONCLUSIONS: Exposure of SMF increases the efficacy of synaptic-transmission in crayfish tail-flip escape circuit and this SMF-induced potentiation is a Ca(2+) dependent phenomenon.

Serum 25-hydroxyvitamin D in erythropoietic protoporphyria.

BACKGROUND: Vitamin D, produced by the action of sunlight on skin, is an important hormone for calcium homeostasis and has been implicated as tumour-protective agent. Some previous studies of photosensitive patients who actively avoid sunlight have failed to show convincing evidence of vitamin D insufficiency. OBJECTIVES: The aim of this study was to characterize the vitamin D status of a large cohort of patients with erythropoietic protoporphyria (EPP). METHODS: U.K. patients with EPP were recruited prospectively and seen locally by a single study investigator. A blood sample was taken for vitamin D assay. All blood analyses were performed in the same laboratory. RESULTS: A cohort of 201 patients with known EPP was seen over a 7-month period between January and July. Thirty-four patients (17%) were deficient in vitamin D and 126 (63%) had insufficient vitamin D. Both insufficiency and deficiency were significantly associated with the total erythrocyte protoporphyrin concentration and inversely with the time in minutes to the onset of symptoms following sunlight exposure. CONCLUSIONS: This is the first report of significant levels of vitamin D deficiency and insufficiency in a large cohort of patients with a photodermatosis. Such individuals are at risk of associated adverse events. In future, clinicians should consider monitoring 25-hydroxyvitamin D levels and instigating oral supplementation or dietary advice if appropriate.

Effects of Smads and BMPs induced by Ga-Al-As laser irradiation on calcification ability of human dental pulp cells.

We investigated the effects of Ga-Al-As laser irradiation on the mineralization ability of human dental pulp (HDP) cells and on Smads and bone morphogenetic protein (BMP) production as one mechanism for the transmission of laser photochemical energy to cells. HDP cells in vitro were irradiated once with a Ga-Al-As laser at 1.0 W for 500 s, and calcified nodule formation was assessed by Alizarin red S staining. The laser irradiation was greater in the laser-irradiated group than in the non-irradiated group. Both calcium production and alkaline phosphatase (ALP) activity were higher after laser irradiation. Expression of mRNAs for Smad1, Smad7, BMPs, ALP, and osteocalcin was greater after laser irradiation, whereas expression of Smad6 mRNA was inhibited. Production of BMP-2 and BMP-4 in conditioned medium was also higher after laser irradiation. These results suggest that Smads and BMPs play important roles in ALP activity and calcification upon laser irradiation of HDP cells.

New theoretical treatment of ion resonance phenomena.

Despite experimental evidence supporting ICR-like interactions in biological systems, to date there is no reasonable theoretical explanation for this phenomenon. The parametric resonance approach introduced by Lednev has enjoyed limited success in predicting the response as a function of the ratio of AC magnetic intensity to that of the DC field, explaining the results in terms of magnetically induced changes in the transition probability of calcium binding states. In the present work, we derive an expression for the velocity of a damped ion with arbitrary q/m under the influence of the Lorentz force. Series solutions to the differential equations reveal transient responses as well as resonance-like terms. One fascinating result is that the expressions for ionic drift velocity include a somewhat similar Bessel function dependence as was previously obtained for the transition probability in parametric resonance. However, in the present work, not only is there an explicit effect due to damping, but the previous Bessel dependence now occurs as a subset of a more general solution, including not only the magnetic field AC/DC ratio as an independent variable, but also the ratio of the cyclotronic frequency Omega to the applied AC frequency omega. In effect, this removes the necessity to explain the ICR interaction as stemming from ion-protein binding sites. We hypothesize that the selectively enhanced drift velocity predicted in this model can explain ICR-like phenomena as resulting from increased interaction probabilities in the vicinity of ion channel gates.