Effect of X-ray free-electron laser-induced shockwaves on haemoglobin microcrystals delivered in a liquid jet.

X-ray free-electron lasers (XFELs) enable obtaining novel insights in structural biology. The recently available MHz repetition rate XFELs allow full data sets to be collected in shorter time and can also decrease sample consumption. However, the microsecond spacing of MHz XFEL pulses raises new challenges, including possible sample damage induced by shock waves that are launched by preceding pulses in the sample-carrying jet. We explored this matter with an X-ray-pump/X-ray-probe experiment employing haemoglobin microcrystals transported via a liquid jet into the XFEL beam. Diffraction data were collected using a shock-wave-free single-pulse scheme as well as the dual-pulse pump-probe scheme. The latter, relative to the former, reveals significant degradation of crystal hit rate, diffraction resolution and data quality. Crystal structures extracted from the two data sets also differ. Since our pump-probe attributes were chosen to emulate EuXFEL operation at its 4.5 MHz maximum pulse rate, this prompts concern about such data collection.

State-of-the-Art Preclinical Photoacoustic Imaging in Oncology: Recent Advances in Cancer Theranostics.

The optical imaging plays an increasing role in preclinical studies, particularly in cancer biology. The combined ultrasound and optical imaging, named photoacoustic imaging (PAI), is an emerging hybrid technique for real-time molecular imaging in preclinical research and recently expanding into clinical setting. PAI can be performed using endogenous contrast, particularly from oxygenated and deoxygenated hemoglobin and melanin, or exogenous contrast agents, sometimes targeted for specific biomarkers, providing comprehensive morphofunctional and molecular information on tumor microenvironment. Overall, PAI has revealed notable opportunities to improve knowledge on tumor pathophysiology and on the biological mechanisms underlying therapy. The aim of this review is to introduce the principles of PAI and to provide a brief overview of current PAI applications in preclinical research, highlighting also on recent advances in clinical translation for cancer diagnosis, staging, and therapy.

Protective properties of Myrtus communis extract against oxidative effects of extremely low-frequency magnetic fields on rat plasma and hemoglobin.

PURPOSE: This study investigates the protective properties of Myrtus communis extract against the oxidative effects of extremely low-frequency magnetic fields (ELFMF). Also, this study is aimed to analyze the conformational changes of hemoglobin, oxidative damages to plasma proteins and antioxidant power of plasma following exposure to ELFMF. MATERIALS AND METHODS: Adult male rats were divided into 3 groups: (1) control, (2) ELFMF exposure, and (3) ELFMF exposure after M. communis extract administration. The magnetic field (0.7 mT, 50 Hz) was produced by a Helmholtz coil for one month, 2 hours a day. The M. communis extract was injected intraperitoneally at a dose of 0.5 mg/kg before exposure to ELFMF. The oxidative effects of ELFMF were studied by evaluating the hemoglobin, methemoglobin (metHb) and hemichrome levels, absorption spectrum of hemoglobin (200-700 nm), oxidative damage to plasma proteins by measuring protein carbonyl (PCO) levels and plasma antioxidant power according to the ferric reducing ability of plasma (FRAP). The mean and standard errors of the mean were determined for each group. One-way ANOVA analysis was used to compare the means of groups. The significance level was considered to be p < .05. Moreover, artificial neural network (ANN) analysis was used to identify the predictive parameters for estimating the oxyhemoglobin (oxyHb) concentration. RESULTS: Exposure to ELFMF decreased the FRAP which was in concomitant with a significant increase in plasma PCO, metHb and hemichrome concentrations (p < .001). Oxidative modifications of Hb were shown by reduction in optical density at 340 nm (globin-heme interaction) and 420 nm (heme-heme interaction). Administration of M. communis extract increased FRAP values and decreased plasma POC, metHb, and hemichrome concentrations. Also, a significant increase in Hb absorbance at 340, 420, 542, and 577 nm showed the protective properties of M. communis extract against ELFMF-induced oxidative stress in erythrocytes. ANN analysis showed that optical absorption of hemoglobin at 520, 577, 542, and 630 nm and concentration of metHb and hemichrome were the most important parameters in predicting the oxyHb concentration. CONCLUSIONS: Myrtus communis extract enhances the ability of erythrocytes and plasma to deal with oxidative conditions during exposure to ELFMF. Also, ANN analysis can predict the most important parameters in relation to Hb structure during oxidative stress.

Mitigation of epidermal growth factor receptor inhibitor-induced side effects utilizing melanin and vascular-specific lasers: A case report series.

The advent of targeted chemotherapy has led to the emergence of new dermatologic toxicities. We sought to use lasers and light devices to treat recalcitrant cutaneous adverse effects related to cancer treatment. Three stage III or IV cancer patients with cutaneous complications due to epidermal growth factor receptor (EGFR) inhibitors were treated with melanin and vascular-specific laser and light technologies. Two patients reported reduction in papulopustular eruption following pulse dye laser (PDL) treatment. Two patients noted reduction in hair growth following intense pulsed light (IPL) and/or Alexandrite laser treatments. One patient was treated with both the PDL and IPL and reported improvement of both EGFR-induced hypertrichosis and papulopustular eruption. Laser and light devices targeting melanin and hemoglobin can be utilized to mitigate the cutaneous adverse effects associated with EGFR inhibitors in patients who have failed traditional therapies. This represents a new option for the cancer patient who is suffering from chemotherapy-induced side effects.

Dynamic optical absorption characteristics of blood after slow and fast heating.

Laser treatment is the most effective therapy in dermatology for vascular skin disorders, such as port-wine stains (PWS). Changes in heat-induced absorbance in blood must be determined for accurate numerical simulation and implementation of multi-pulse laser therapy for treatment of PWS. Thermally induced absorbance changes in hemoglobin in blood were compared in vitro between slow water bath heating and fast heating irradiated by using sub-millisecond Nd:YAG laser. Blood composition at different temperatures was calculated by comparing blood absorption spectra with those of pure HbO2, Hb, and metHb at room temperature. Blood absorbance to heat energy were categorized into three stages distinguished by metHb and coagulation points, which are the validity and security thresholds of the optimized therapy, respectively. Rapid laser heating can distinctively enhance blood absorbance by photochemically induced strong instability compared with slow heating at a constant temperature. Slow heating facilitates metHb point at 70 °C and coagulation point at 75 °C as the temperature of the water bath increases. However, the temperature at which metHb or coagulation point shifts to higher than 10 °C when pulses and fluence in laser irradiation change. Laser fluence less than 20 J/cm2 and more than 50 J/cm2 is unsuitable for laser treatment because of its low probability to coagulate vascular hyperplasia and high probability to damage normal tissues adjacent to target lesions, respectively. Few bubbles formed after mediate fluence is beneficial to minimize adverse side-effects. Considering blood absorbance, temperature evolution, and bubble formation, we recommend 30-40 J/cm2 and 2-4 Hz frequency as the optimal laser parameters in sub-millisecond Nd:YAG laser.

Tumor Burden and Intraosseous Metabolic Activity as Predictors of Bone Marrow Failure during Radioisotope Therapy in Metastasized Prostate Cancer Patients.

RATIONALE: Radium-223-Dichloride (Ra-223) is an alpha-emitter, used to treat bone metastases. Patients with high metastatic burden and/or with increased trabecular bone uptake could present a higher incidence of hematologic toxicity. We hypothesized that these two factors are predictors of bone marrow failure. MATERIAL AND METHODS: A computer algorithm discriminated between trabecular bone (BVol) and tumor metastases (MVol) within pretherapeutic whole-body skeletal SPECT/CT (N = 47). The program calculated the metastatic invasion percent (INV%) as the MVol/(MVol + BVol) ratio and extracted the BVol mean counts. BVol counts were correlated to % drop of hemoglobin (Hb), leukocytes (WBC), and platelets (PLT) after 3/6 Ra-223 cycles. Patient-specific and computational-derived parameters were tested as predictors of hematologic toxicity with MANOVA. RESULTS: BVol counts correlated with drop of Hb (R = 0,65, p < 0.01) and PLT (R = 0,45, p < 0.01). Appendicular BVol counts showed a better correlation (p < 0.05, p < 0.01, and p < 0.001 for Hb, WBC, and PLT, resp.). INV% directly correlated with BVol counts (R = 0.68, p < 0.001). At MANOVA, grade III/IV toxicity was predicted by INV% (p < 0.01), by long-bone invasion (p < 0.005), and by BVol counts (p < 0.05). CONCLUSIONS: In patients with significant bone tumor burden, degree of bone invasion and trabecular bone uptake are predictors of subsequent bone marrow failure.

Influence of the first radioactive iodine ablation on peripheral complete blood count in patients with differentiated thyroid cancer.

Radioactive iodine (RAI) is considered to be related with hematologic changes. This study aimed to evaluate influence of the first RAI ablation on peripheral complete blood count (CBC) in patients with differentiated thyroid cancer (DTC).Data of CBC at baseline and 6 months after RAI were obtained in 385 patients with DTC with approximately 3700 MBq I (ranging 2220-7585 MBq). Further comparison was done in 196 patients with 1-month postablation data available. Routine blood examinations were performed to determine impact of RAI on white blood cell (WBC), red blood cell (RBC), hemoglobin, platelet, neutrophil, lymphocyte, and monocyte in both sexes. Continuous variables were compared by paired t tests and independent samples t test, and categorical variables were compared by chi-square analysis. Data with repeated measurements were analyzed by analysis of variance.The first RAI after thyroidectomy was associated with mild, yet significant declines in WBC, platelet, and lymphocyte, which persisted for 6 months. One month after RAI, significant declines were found in all CBC, including RBC and hemoglobin (all P < 0.05). While CBC partly recovered 6 months after RAI, this follow-up CBC still demonstrated significant declines in WBC, platelet, and lymphocyte (all P < 0.05) without gender differences. Significant rises in RBC and hemoglobin in males and females were found. The decline of platelet in females was more obvious than in males at 3700 to 4440 MBq of RAI. On the contrary, the rises of RBC and hemoglobin in males were higher than in females. There were no significant complications during the follow-up.WBC and platelet decreased obviously 1 month after RAI. While they partly recovered 6 months after RAI, they were still lower than the baseline. However, RBC and hemoglobin transiently decreased at 1 month and then increased to levels even higher than baseline 6 months later. At 3700 to 4440 MBq of RAI, the decline of platelet in females was more obvious than in males. Yet, rises of RBC and hemoglobin in males were higher than in females. The risks associated with these changes are unlikely to outweigh the potential benefits of RAI in patients with DTC.

Dose to specific subregions of pelvic bone marrow defined with FDG-PET as a predictor of hematologic nadirs during concomitant chemoradiation in anal cancer patients.

To test the hypothesis that irradiated volume of specific subregions of pelvic active bone marrow as detected by (18)FDG-PET may be a predictor of decreased blood cells nadirs in anal cancer patients undergoing concurrent chemoradiation, we analyzed 44 patients submitted to IMRT and concurrent chemotherapy. Several bony structures were defined: pelvic and lumbar-sacral (LSBM), lower pelvis (LPBM) and iliac (IBM) bone marrow. Active BM was characterized employing (18)FDG-PET and characterized in all subregions as the volume having standard uptake values (SUVs) higher than SUVmean. All other regions were defined as inactive BM. On dose-volume histograms, dosimetric parameters were taken. Endpoints included white blood cell count (WBC), absolute neutrophil count (ANC), hemoglobin (Hb) and platelet (Plt) nadirs. Generalized linear modeling was used to find correlations between dosimetric variables and blood cells nadirs. WBC nadir was significantly correlated with LSBM mean dose (ß = -1.852; 95 % CI -3.205/-0.500; p = 0.009), V10 (ß = -2.153; 95 % CI -4.263/-0.721; p = 0.002), V20 (ß = -2.081; 95 % CI -4.880/-0.112; p = 0.003), V30 (ß = -1.971; 95 % CI -4.748/-0.090; p = 0.023) and IBM V10 (ß = -0.073; 95 % CI -0.106/-0.023; p = 0.016). ANC nadir found to be significantly associated with LSBM V10 (ß = -1.878; 95 % CI -4.799/-0.643; p = 0.025), V20 (ß = -1.765; 95 % CI -4.050/-0.613; p = 0.030) and IBM V10 (ß = -0.039; 95 % CI -0.066/-0.010; p = 0.027). Borderline significance was found for correlation between Plt nadir and LSBM V30 (ß = -0.056; 95 % CI -2.748/-0.187; p = 0.060), V40 (ß = -0.059; 95 % CI -3.112/-0.150; p = 0.060) and IBM V30 (ß = -0.028; 95 % CI -0.074/-0.023; p = 0.056). No inactive BM subsites were found to be correlated with any blood cell nadir. (18)FDG-PET is able to define active bone marrow within pelvic osseous structures. LSBM is the strongest predictor of decreased blood cells nadirs in anal cancer patients undergoing concurrent chemoradiation.

Differential sensitivity of Chironomus and human hemoglobin to gamma radiation.

Chironomus ramosus is known to tolerate high doses of gamma radiation exposure. Larvae of this insect possess more than 95% of hemoglobin (Hb) in its circulatory hemolymph. This is a comparative study to see effect of gamma radiation on Hb of Chironomus and humans, two evolutionarily diverse organisms one having extracellular and the other intracellular Hb respectively. Stability and integrity of Chironomus and human Hb to gamma radiation was compared using biophysical techniques like Dynamic Light Scattering (DLS), UV-visible spectroscopy, fluorescence spectrometry and CD spectroscopy after exposure of whole larvae, larval hemolymph, human peripheral blood, purified Chironomus and human Hb. Sequence- and structure-based bioinformatics methods were used to analyze the sequence and structural similarities or differences in the heme pockets of respective Hbs. Resistivity of Chironomus Hb to gamma radiation is remarkably higher than human Hb. Human Hb exhibited loss of heme iron at a relatively low dose of gamma radiation exposure as compared to Chironomus Hb. Unlike human Hb, the heme pocket of Chironomus Hb is rich in aromatic amino acids. Higher hydophobicity around heme pocket confers stability of Chironomus Hb compared to human Hb. Previously reported gamma radiation tolerance of Chironomus can be largely attributed to its evolutionarily ancient form of extracellular Hb as evident from the present study.

Carboxylated nanodiamonds inhibit γ-irradiation damage of human red blood cells.

Nanodiamonds when carboxylated (cNDs) act as reducing agents and hence could limit oxidative damage in biological systems. Gamma (γ)-irradiation of whole blood or its components is required in immunocompetent patients to prevent transfusion-associated graft versus host disease (TA-GVHD). However, γ-irradiation of blood also deoxygenates red blood cells (RBCs) and induces oxidative damage, including abnormalities in cellular membranes and hemolysis. Using atomic force microscopy (AFM) and Raman spectroscopy, we examined the effect of cNDs on γ-irradiation mediated deoxygenation and morphological damage of RBCs. γ-Radiation induced several morphological phenotypes, including stomatocytes, codocytes and echinocytes. While stomatocytes and codocytes are reversibly damaged RBCs, echinocytes are irreversibly damaged. AFM images show significantly fewer echinocytes among cND-treated γ-irradiated RBCs. The Raman spectra of γ-irradiated RBCs had more oxygenated hemoglobin patterns when cND-treated, resembling those of normal, non-irradiated RBCs, compared to the non-cND-treated RBCs. cND inhibited hemoglobin deoxygenation and morphological damage, possibly by neutralizing the free radicals generated during γ-irradiation. Thus cNDs have the therapeutic potential to preserve the quality of stored blood following γ-irradiation.

Functional Features of Microcirculation System and its Possibilities of Oxygen Transport in Children and Youths of Bryansk Region in Conditions of Radioecological Pressure.

The questions of influence of low radiation doses on microcirculation of blood in ontogeny of males from 7 to 27 years are presented in the article. Using the method of laser Doppler ultrasounds, optical oximetry and laser fluorescent diagnostics, we studied the blood perfusion level in the microcirculation system of 315 schoolchildren and students, considered the regulation mechanisms of microcirculation, the level of oxygen saturation of hemoglobin both in the circulation system and mixed blood, the index of oxygen utilization in tissues and the value of fluorescent use of oxygen. We received the information about the changes in the frequency of occurrence of different microcirculation types associated with the age and region of residence. In the case of higher radiation levels we marked a significant increase of individuals with the "extreme" microcirculation type (hypoemic and hyperemic) against the background of the decreased mesoemic type. A special feature of the metabolism process in children, teenagers, and youths is a decrease of the microcirculation density with an increase of the myogenic tone of metaarterioles and precapillary sphincters. The tone of arterioles grows with age. As a result of the limited blood volume, oxygen. is pulled compensatory from blood in larger amounts; it is shown from a significant decrease of the level of oxygen saturation in mixed blood. The strongest differences are shown for the hypoemic and hyperemic microcirculation type. Dwelling on the areas with radio-ecological pressure is accompanied by an increase in the fluorescent index of oxygen use. The level of the total oxygen use in these individuals is higher than in those living in radiation favorable areas.

Effect of incubating egg exposure to magnetic field on the biophysical blood properties of newly-hatched chicks.

Due to widespread of human exposure to electromagnetic fields, there has been increasing public concern about the potential health risks from low-frequency electromagnetic fields; ELF-EMF. The magnetic fields (MFs) affects functions of the living organisms, such as DNA synthesis and ion transportation through the cell membranes. In the present work, the effects of short-term exposure to magnetic fields (MFs) prior to incubation were investigated on the biophysical blood properties of chicks hatched from layer-type breeder eggs. The eggs were exposed to a MF of 0.75 mT at 50 Hz for 20, 40 and 60 min before incubation. This study was performed by measuring the dielectric relaxation of hemoglobin (Hb) molecules and the membrane solubility of red blood cells (RBCs) using the non-ionic detergent octylglucoside. Exposure of the eggs to a MF increased the conductivity of the Hb molecules. The pronounced increase in the conductivity of the exposed eggs might be attributed to an increase in the surface charge of the Hb macromolecules, resulted from the formation of highly active molecular species. This speculation can be supported by the increase in the relaxation time of the exposed groups. The solubilization process of the RBC membrane indicates a loss in the mobility of RBCs in the blood of hatching chicks.

Mechanism of two-photon excited hemoglobin fluorescence emission.

Hemoglobin, one of the most important proteins in the human body, is composed of "heme" groups (iron-containing rings) and "globins" (proteins). We investigate the two-photon excited fluorescence of hemoglobin and its subunit components (heme and globin). We measure the hemoglobin fluorescence lifetime by using a streak camera of ps resolution and confirm that its lifetime is in femtosecond scale. In the study of the fluorescence properties of heme and globin, the experimental results reveal that heme is the sole fluorophore of hemoglobin. Hemoglobin fluorescence can be effectively excited only via two-photon process, because heme has a centrosymmetric molecular structure and two-photon allowed transition is forbidden for single-photon process and vice versa due to the Laporte parity selection rule.

Effects of 10-GHz microwaves on hematological parameters in Swiss albino mice and their modulation by Prunus avium.

The objective of this study was to investigate the modulatory role of Prunus avium fruit extract (PAE) on several blood parameters after exposure to 10-GHz microwaves. Swiss albino mice from an inbred colony were selected and divided into 3 groups. Mice in group I served as the control; they were placed in a Plexiglas cage (without energizing the system) for 2 hours/day for 30 consecutive days. Group II mice were exposed to 10-GHz microwaves for 2 hours/day for 30 consecutive days. Mice in group III received PAE (500 mg/kg/body weight) orally once daily 1 hour before exposure to 10-GHz microwaves (2 hours/day) for 30 consecutive days. After 30 days of treatment, blood samples were collected from mice in all groups and analyzed. Hemoglobin, monocytes, packed cell volume, red blood cells, mean corpuscular hemoglobin concentration declined significantly (P ≤ 0.01), whereas white blood cells, lymphocytes, erythrocyte sedimentation rate, and mean corpuscular volume increased significantly (P ≤ 0.01) compared to the control group (group I). Cholesterol, alkaline phosphatase, and lipid peroxidation also increased significantly (P ≤ 0.01). Depletion in blood sugar, total protein, acid phosphatase, and glutathione levels was noted after microwave exposure compared with levels in the sham-exposed (control) mice. Histopathological alterations in blood cells also were seen. Signs of improvements in the hematological, biochemical, and histopathological parameters were recorded in group III, where PAE was supplemented before exposure. Exposure to microwaves influences hematological parameters, which could be ameliorated by the supplementation of PAE.

[Role of optical properties of the venous wall for endovenous laser obliteration].

Presented herein are the results of studying the optical density of water, blood, and venous-wall tissue for various-wavelength laser radiation, with determining the peaks of absorption of radiation by the above-mentioned media. The absorption peaks in water and blood correspond to wavelengths of 1,450 and 1,935 nm, respectively. Peaks of absorption in the venous-wall tissue are within the intervals equaling 650-950 nm, 1,445-1,455 nm, and more than 1,900 nm. Also determined was the optical density of the veins for the most frequently used in clinical practice wavelengths, i. e. 1,030 and 1,470 nm, with the calculation of the portion of the absorbed energy depending on thickness of the layer of the absorbing substance. Based on the obtained findings, a conclusion was drawn on better utilization of the energy of one-and-a-half-micron range laser radiation and on its preferable use for endovenous laser obliteration (EVLO).

The effect of γ-radiation on the hemoglobin of stored red blood cells: the involvement of oxidative stress in hemoglobin conformation.

The aim of the present work was to evaluate the redox and oligomeric effects associated with the human hemoglobin of stored red blood cells that had been previously submitted to gamma radiation. Whole blood was collected from healthy donors and irradiated with 25 Gy of γ-radiation within 24 h of collection. At days 3, 5, 7, 9, 11, 14, and 28 postirradiation, fractions were removed and centrifuged, and the levels of methehemoglobin and oxyhemoglobin were measured. Hb was isolated to measure the denaturation and UV-vis spectra. The results from electrophoresis demonstrated that there was no fragmentation or cross-linking of the hemoglobin. However, ferrous center oxidation was identified as a very significant process. This mechanism is likely through an autoxidation process of the ferrous heme center, which has a maximal intensity between 5 and 7 days of storage. Interestingly, a subsequent reduction of the oxidized heme species was observed, and after 9 days of storage, the difference between the ferric species present in the control and irradiated samples was not representative. This interesting fact suggests a type of "protective action" by the blood to control the oxidative stress generated by the gamma irradiation. The UV-vis measurements demonstrated that the oxidized species was predominantly formed by hemichrome species (bis-histidine ferric heme species), which are usually associated with Heinz bodies. After 28 days of storage, evidence from the UV-vis measurements indicated that the oxidation of the irradiated sample was much higher than that observed in the control sample. These results demonstrate that despite the minimal polypeptide changes observed in the hemoglobin of stored red blood cells after gamma irradiation, the oxidation of the heme metallic center is not irrelevant and must be controlled to improve the hematological clinical procedures associated with the storage of red blood cells.

Selective X-ray-induced NO photodissociation in haemoglobin crystals: evidence from a Raman-assisted crystallographic study.

Despite their high physiological relevance, haemoglobin crystal structures with NO bound to haem constitute less than 1% of the total ligated haemoglobins (Hbs) deposited in the Protein Data Bank. The major difficulty in obtaining NO-ligated Hbs is most likely to be related to the oxidative denitrosylation caused by the high reactivity of the nitrosylated species with O(2). Here, using Raman-assisted X-ray crystallography, it is shown that under X-ray exposure (at four different radiation doses) crystals of nitrosylated haemoglobin from Trematomus bernacchii undergo a transition, mainly in the ß chains, that generates a pentacoordinate species owing to photodissociation of the Fe-NO bond. These data provide a physical explanation for the low number of nitrosylated Hb structures available in the literature.

The influence of pulsed electric field on hematological parameters in rat.

The aim of the present study is to investigate whether or not pulsed electric field (PEF) affects some hematological parameters in rats. Sixteen healthy male Wistar rats weighting 150-200 g were used and were randomly divided into two groups. Exposure group (n = 8) was exposed to a PEF (10 kV m⁻¹ for 1 h d⁻¹) for 10 consecutive days. The control group rats (n = 8) were not exposed to PEF. The following hematological parameters were measured in both the groups: white blood cells (WBCs), red blood cells (RBCs), hemoglobin (Hb), hematocrit (Ht) and platelets (PLTs). Some of the hematological parameters under investigation were similar in both the groups. Exposure group, exposed for 1 h d⁻¹ during 10 consecutive days, induced a significant increase in the rates of WBC (p < 0.05), RBC (p < 0.05), Hb (p < 0.05), Ht (p < 0.05) and PLTs (p < 0.05) in blood when compared with control. These results suggest that PEFs affect the hematological parameters in rat. Results of the parameters are statistically significant.

Ultraviolet irradiation-dependent fluorescence enhancement of hemoglobin catalyzed by reactive oxygen species.

Ultraviolet (UV) light has a potent effect on biological organisms. Hemoglobin, an oxygen-transport protein, plays an irreplaceable role in sustaining life of all vertebrates. In this study we scrutinize the effects of ultraviolet irradiation (UVI) as well as visible irradiation on the fluorescence characteristics of bovine hemoglobin (BHb) in vitro. Data show that UVI results in fluorescence enhancement of BHb in a dose-dependent manner. Furthermore, UVI-induced fluorescence enhancement is significantly increased when BHb is pretreated with hydrogen peroxide (H(2)O(2)), a type of reactive oxygen species (ROS). Meanwhile, The water-soluble antioxidant vitamin C suppresses this UVI-induced fluorescence enhancement. In contrast, green light irradiation does not lead to fluorescence enhancement of BHb no matter whether H(2)O(2) is acting on the BHb solution or not. Taken together, these results indicate that catalysis of ROS and UVI-dependent irradiation play two key roles in the process of UVI-induced fluorescence enhancement of BHb.