Biomedical subjects

Da Xing

Publications and source records attributed to Da Xing.

At least 19 recordsLinked to original sources

PubMed2006

Single cell analysis of PKC activation during proliferation and apoptosis induced by laser irradiation.

Laser irradiation has been shown to trigger cellular proliferation and apoptosis in various cell types. Studying the signaling pathways involved in the laser irradiation is important for understanding these processes. In present study, to monitor the protein kinase Cs (PKCs) activity in living cells in real time, we transfected and screened human lung adenocarcinoma cells (ASTC-a-1) stably expressing C kinase activity reporter (CKAR) constructed based on fluorescence resonance energy transfer (FRET) technique. The CKAR is a specific, reversible reporter of phosphorylation by PKCs and it can monitor the ongoing balance between PKCs and phosphatases. The increasing dynamics of PKCs activity is monitored during cell proliferation induced by low-power laser irradiation (LPLI) (0.8 J/cm2) in serum-starved ASTC-a-1 cells stably expressing CKAR reporter using FRET imaging on laser scanning confocal microscope and using spectrofluorometric analysis on a luminescence spectrometer, respectively. However, the decreasing dynamics of PKCs activity has been monitored in real time using FRET imaging for the cells treated with high fluence LPLI (60 J/cm2), which was previously found to induce cell apoptosis. Taken together, LPLI induces the ASTC-a-1 cell proliferation by specifically activating PKCs. However, PKCs activity decreases during cell apoptosis induced by high fluence LPLI. Our results indicate that PKCs play an important role in the laser irradiation-induced biological effects.

Apoptosis↗

PubMed2005

Detection of caspase-3 activation in single cells by fluorescence resonance energy transfer during photodynamic therapy induced apoptosis.

In many apoptosis pathways, activation of caspase-3 is considered the final stage. In this study, we studied PDT induced caspase-3 activation with fluorescence resonance energy transfer (FRET) technique. A recombinant caspase-3 substrate, SCAT3, was used as the FRET probe. FRET fluorescence images were collected after PDT or TNF-alpha induced apoptosis. By analyzing the dynamic changes of FRET fluorescence, the results indicate that the caspase-3 activation started immediately after the PDT treatment. In contrast, FRET disruption caused by caspase-3 activation started at 3h after TNF-alpha treatment, due to different signaling pathway. The results have proofed, for the first time, that FRET is a sensitive technique that can be used to investigate PDT-induced activation of caspase-3 in real-time and in single cells. By choosing appropriate recombinant substrates as FRET probes, it is likely that FRET technique will provide a new real-time means to study the mechanism of PDT at single cell level.

Adenocarcinoma↗

PubMed2005

Determination of optical properties of normal and adenomatous human colon tissues in vitro using integrating sphere techniques.

AIM: The purpose of the present study is to compare the optical properties of normal human colon mucosa/submucosa and muscle layer/chorion, and adenomatous human colon mucosa/submucosa and muscle layer/chorion in vitro at 476.5, 488, 496.5, 514.5 and 532 nm. We believe these differences in optical properties should help differential diagnosis of human colon tissues by using optical methods. METHODS: In vitro optical properties were investigated for four kinds of tissues: normal human colon mucosa/submucosa and muscle layer/chorion, and adenomatous human colon mucosa/submucosa and muscle layer/chorion. Tissue samples were taken from 13 human colons (13 adenomatous, 13 normal). From the normal human colons a total of 26 tissue samples, with a mean thickness of 0.40 mm, were used (13 from mucosa/submucosa and 13 from muscle layer/chorion), and from the adenomatous human bladders a total of 26 tissue samples, with a mean thickness of 0.40 mm, were used (13 from mucosa/submucosa and 13 from muscle layer/chorion). The measurements were performed using a double-integrating-sphere setup and the optical properties were assessed from these measurements using the adding-doubling method that was considered reliable. RESULTS: The results of measurement showed that there were significant differences in the absorption coefficients and scattering coefficients between normal and adenomatous human colon mucosa/submucosa at the same wavelength, and there were also significant differences in the two optical parameters between both colon muscle layer/chorion at the same wavelength. And there were large differences in the anisotropy factors between both colon mucosa/submucosa at the same wavelength, there were also large differences in the anisotropy factors between both colon muscle layer/chorion at the same wavelength. There were large differences in the value ranges of the absorption coefficients, scattering coefficients and anisotropy factors between both colon mucosa/submucosa, and there were also large differences in these value ranges between both colon muscle layer/chorion. There are the same orders of magnitude in the absorption coefficients for four kinds of colon tissues. The scattering coefficients of these tissues exceed the absorption coefficients by at least two orders of magnitude. CONCLUSION: There were large differences in the three optical parameters between normal and adenomatous human colon mucosa/submucosa at the same laser wavelength, and there were also large differences in these parameters between both colon muscle layer/chorion at the same laser wavelength. Large differences in optical parameters indicate that there were large differences in compositions and structures between both colon mucosa/submucosa, and between both colon muscle layer/chorion. Optical parameters for four kinds of colon tissues are wavelength dependent, and these differences would be useful and helpful in clinical applications of laser and tumors photodynamic therapy (PDT).

Adenomatous Polyposis Coli↗

PubMed2005

Measuring dynamics of caspase-3 activity in living cells using FRET technique during apoptosis induced by high fluence low-power laser irradiation.

BACKGROUND AND OBJECTIVES: Low-power laser irradiation (LPLI) has been used for therapies such as curing spinal cord injury, healing wound etc. Yet, the mechanism of LPLI remains unclear. In order to determine the effects of high fluence LPLI on cell growth and caspase-3 activity, we have measured the dynamics of caspase-3 activity during cell apoptosis induced by high fluence LPLI treatment. STUDY DESIGN/MATERIALS AND METHODS: He-Ne laser was used to irradiate human lung adenocarcinoma cells (ASTC-a-1). Cell Counting Kit-8 was used for cytotoxicity assay. A fluorescent microscope was used to perform fluorescence resonance energy transfer (FRET) imaging. A luminescence spectrometer was used to acquire the fluorescent emission spectrum. Statistical analysis was performed with Student's paired t-test. RESULTS: Cytotoxicity assay showed that when light irradiation fluence exceeded 60 J/cm2, LPLI treatment induced ASTC-a-1 cell apoptosis in a fluence-dependent manner. FRET imaging and spectrofluorometric analysis demonstrated that caspase-3 was activated during high fluence LPLI-induced cell apoptosis. CONCLUSIONS: Using FRET technique, we have reported that high fluence LPLI can induce human lung adenocarcinoma cells (ASTC-a-1) apoptosis. The activation of caspase-3 plays an important role in the apoptotic process.

Adenocarcinoma↗

PubMed2005

[Spectral properties of hematoporphyrin derivative after interacted with human serum albumin].

The spectral properties of photosensitizer HpD, human serum albumin (HSA) and their complex have been studied. The results show that HpD can form HpD-HSA complex with HSA in physiological condition. Compared with pure HpD, the maximum absorption and the fluorescence peaks for HpD-HSA complex had 8-10 nm red-shift. When HpD-HSA complex was excited by the light of corresponding to excitation peaks of HSA (228 and 279 nm) and HpD (394 nm), it was found that the absorption of HSA and HpD both contributed to the emission of HpD-HSA complex at 622 nm. The complex of HpD-HSA was individually excited by wavelengths corresponding to HpD absorption peaks of 402, 502, 537 and 570 nm, and the excitation efficiency of HpD-HSA at pumping wavelength of 537 and 570 nm was higher than that of HpD. The results demonstrate that the red-shift caused by the interaction of HpD and the special proteins in blood should be considered in selecting the excitation and emission wavelength in photodynamic diagnosis and therapy. The results also indicate that the excitation efficiency of porphyrin-protein complex in vivo is higher than that of HpD in vitro when a longer wavelength light corresponding to the week absorption peaks of porphyrin-protein complex is used in photodynamic therapy.

Hematoporphyrin Derivative↗

PubMed2004

A method to quantitatively detect H-ras point mutation based on electrochemiluminescence.

Conventional methods for point mutation detection are usually multi-stage, laborious, and need to use radioactive isotopes or other hazardous materials, and the assay results are often semi-quantitative. In this work, a protocol for quantitative detection of H-ras point mutation was developed. Electrochemiluminescence (ECL) assay was coupled with restriction endonuclease digestion directly from PCR products. Only the wild-type amplicon containing the endonuclease's recognition site can be cut off, and thus cannot be detected by ECL assay. Using the PCR-ECL method, 30 bladder cancer samples were analyzed for possible point mutation at codon 12 of H-ras oncogene. The results show that the detection limit for H-ras amplicon is 100 fmol and the linear range is more than three orders of magnitude. The point mutation was found in 14 (46.7%) out of 30 bladder cancer samples. The experiment results demonstrate that the PCR-ECL method is a feasible quantitative approach for point mutation detection due to its safety, high sensitivity, and simplicity.

Calibration↗

PubMed2004

High sensitive approach for point mutation detection based on electrochemiluminescence.

An electrochemiluminescence-polymerase chain reaction (ECL-PCR) method for point mutation detection has been developed. The target is amplified using a tris (bipyridine) ruthenium (TBR)-labeled forward and a biotinylated reverse primer. The amplification products are digested with specific restriction enzyme, then captured onto streptavidin-coated paramagnetic beads, and detected by measuring the ECL signal of the TBR label. The established technique was further applied to detect a specific point mutation in H-ras oncogene in T24 cell line. The results show that the system has a low detection limit of 100 fmol and a linear range of more than 3 orders of magnitude for H-ras amplicon; the two genotypes can be reliably discriminated. In summary, the mutant specific ECL-PCR method can be used to detect a point mutation that creates or destroys a restriction site in any gene. It is useful in single nucleotide polymorphism (SNP) and mutation detection due to its safety, high sensitivity and simplicity.

Biomarkers, Tumor↗

PubMed2004

Detection of genetically modified organisms by electrochemiluminescence PCR method.

With the development of biotechnology, more and more genetically modified organisms (GMOs) have entered commercial market. Because of the safety concerns, detection and characterization of GMOs have attracted much attention recently. In this study, electrochemiluminescence polymerase chain reaction (ECL-PCR) combined with hybridization technique was applied to detect the GMOs in genetically modified (GM) soybeans and papayas for the first time. Whether the soybeans and the papayas contain GM components was discriminated by detecting the Cauliflower mosaic virus 35S (CaMV35S) promoter. The experiment results show that the detection limit for CaMV35S promoter is 100 fmol, and the GM components can be clearly identified in GM soybeans and papayas. The technique may provide a new means in GMOs detection due to its simplicity and high efficiency.

Carica↗

PubMed2004

A novel method for measuring photosynthesis using delayed fluorescence of chloroplast.

Photosynthesis is the most important chemical reaction in the world. The measurement of plant photosynthesis rate plays an important role in agriculture. Light-induced delayed fluorescence (DF) in plants is an intrinsic label of the efficiency of charge separation at P680 in photosystem II (PS II). In this paper, we have developed a biosensor that can accurately measure the plant photosynthesis ability by means of DF. Compared with common methods for measuring the photosynthesis rate based on consumption of CO2, the proposed technique can quantify the plant photosynthesis ability with less influence of the environment. The biosensor is an all-weather measuring instrument, it has its own illumination power and utilizes intrinsic DF as the measurement marker. The current investigation has revealed that, there is a good correspondence between the results measured by the biosensor and that by commercially available portable photosynthesis system under controlled conditions. We thus conclude that DF is an excellent marker for evaluating plant photosynthesis ability under its biological status with less interferences of the environment.

Biosensing Techniques↗

PubMed2004

Photoacoustic imaging with deconvolution algorithm.

The impulse response of the ultrasonic transducer used for detection is crucial for photoacoustic imaging with high resolution. We demonstrate a reconstruction method that allows the optical absorption distribution of a sample to be reconstructed without knowing the impulse response of the ultrasonic transducer. A convolution relationship between photoacoustic signals measured by an ultrasound transducer and optical absorption distribution is developed. Based on this theory, the projection of the optical absorption distribution of a sample can be obtained directly by deconvolving the recorded PA signal originating from a point source out of that from the sample. And a modified filtered back projection algorithm is used to reconstruct the optical absorption distribution. We constructed a photoacoustic imaging system to validate the reconstruction method and the experimental results demonstrated that the reconstructed images agreed well with the original phantom samples. The spatial resolution of the system reaches 0.3 mm.

Acoustics↗

PubMed2004

Fast photoacoustic imaging system based on 320-element linear transducer array.

A fast photoacoustic (PA) imaging system, based on a 320-transducer linear array, was developed and tested on a tissue phantom. To reconstruct a test tomographic image, 64 time-domain PA signals were acquired from a tissue phantom with embedded light-absorption targets. A signal acquisition was accomplished by utilizing 11 phase-controlled sub-arrays, each consisting of four transducers. The results show that the system can rapidly map the optical absorption of a tissue phantom and effectively detect the embedded light-absorbing target. By utilizing the multi-element linear transducer array and phase-controlled imaging algorithm, we thus can acquire PA tomography more efficiently, compared to other existing technology and algorithms. The methodology and equipment thus provide a rapid and reliable approach to PA imaging that may have potential applications in noninvasive imaging and clinic diagnosis.

Acoustics↗

PubMed2004

Rapid and sensitive immunomagnetic-electrochemiluminescent detection of p53 antibodies in human serum.

The mutation of tumor suppressor p53 gene is common in malignant tumor. p53 antibodies are products of immunoresponse against abnormal p53 protein. It has been found that p53 antibodies are of importance in tumor's diagnosis, prognosis and relapse monitoring. However, current method for detecting p53 antibodies, i.e. enzyme-linked immunosorbent assay (ELISA), requires a long time with multiple steps, and the assay is only semi-quantitative. In this work, a protocol for quantitative detection of p53 antibodies in human serum using immunomagnetic electrochemiluminescence (IM-ECL) was devoloped. The immunoassay format consisted of a three antibody sandwich in which a biotinylated capture antibody, was banded with the commercial p53 protein. A detector antibody was added to bind the p53 protein at another site. Then, secondary antibody, labeled with ruthenium(II) tris-bipyridal, was added and, when bound to the bead immunocompiex, generated light in the presence of an excess of tripropylamine. The light was detected and measured by the analyzer made by us. Our experimental results indicate that the sensitivity of this assay was 10 pg of p53 antibodies per ml of reference serum (normal human serum). A stable calibration curve with a wide dynamic range was established. The calibration curve was linear from 0.01 to 1000 ng/ml, thus, making quantitation possible. An immunologic prozone effect was observed above 1000 ng p53 antibodies per milliliter of serum. Serum samples from lung and nasopharyngeal carcinoma patients were tested using the IM-ECL assay. The positive rate of p53 antibodies were 28.6% in lung carcinoma and 8.33% in nasopharyngeal carcinoma, respectively. p53 antibody concentration in the carcerous human sera were quantified from the calibration curve. In the case of lung carcinoma, a trend was found that a higher p53 antibody concentration in the serum was likely linked to a higher stage of the cancer. This trend was not found in nasopharyngeal carcinoma. The assay uses only 50 microl of sample per test and requires a 30-min incubation period in addition to a 50 s acquisition time. This assay has several advantages over the commonly used ELISA method in terms of sensitivity, linear range, and assay time. Results of the study suggest that IM-ECL is a feasible method for rapid and sensitive detection of p53 antibodies in human serum.

Antibodies↗

PubMed2004

[Comparative research on attenuation characteristics of human bladder cancer tissue at different wavelengths of laser and their linearly polarized laser in vitro].

In this paper, a double-integrating-spheres system, the basic principle of measuring technology of ray radiation, and the optical model of biological tissues were used for the study. Attenuation characteristics of human bladder cancer tissue at 467.5, 488, 496.5, 514.5 and 532 nm laser and their linearly polarized laser irradiation were studied. The results of measurement showed that the attenuation characteristics of human bladder cancer tissue in Kubelka-Munk two-flux model were different at different wavelengths of laser irradiation in the range of five different laser wavelengths. There were significant differences in the total attenuation or effective attenuation coefficients of human bladder cancer tissue at 476.5, 496.5, and 532 nm wavelengths of laser and their linearly polarized laser irradiation (P>0.05), and there were no significant differences at 488 and 514.5 nm wavelengths of laser and their linearly polarized laser irradiation in two-flux model (P>0.05). The total attenuation and effective attenuation coefficients of human bladder cancer tissue at 532 nm laser and its linearly polarized laser irradiation were obviously bigger than those at other four different wavelengths of laser and their linearly polarized laser irradiation in two-flux model. The total attenuation and effective attenuation coefficients of human bladder cancer tissue at five different wavelengths of laser and their linearly polarized laser irradiation increased with the decrease of these wavelengths, there were significant differences in those at 476.5, 496.5 and 514.5 nm wavelengths of laser and their linearly polarized laser irradiation (P<0.05), and there were no significant differences in those at 488 and 532 nm wavelengths of laser and their linearly polarized laser irradiation in light transport theory (P>0.05).

Cell Line↗

PubMed2004

[Optical properties of human normal bladder tissue at five different wavelengths of laser and their linearly polarized laser irradiation in vitro].

A double-integrating-spheres system, the basic principle of measuring technology of radiation, and an optical model of biological tissues were used for the study. Optical properties of human normal bladder tissue at 476.5, 488, 496.5, 514.5 and 532 nm of laser and their linearly polarized laser irradiation were studied. The results of measurement showed that total attenuation coefficient and scattering coefficient of human normal bladder tissue at these wavelengths of laser and their linearly polarized laser irradiation increased with decreasing wavelengths. And these was an obvious distinction between the results at these wavelengths of laser and their linearly polarized laser irradiation. Absorption coefficient of human normal bladder tissue at these wavelengths of laser and their linearly polarized laser irradiation was tardily increased with decreasing wavelengths. But there were a number of gurgitations. And these were independent of the wavelengths of laser or their linearly polarized laser irradiation. Mean cosine of scattering of human normal bladder tissue at these wavelengths of laser and their linearly polarized laser irradiation also increased with decreasing wavelengths. And these was an obvious distinction with these wavelengths of laser and their linearly polarized laser irradiation. But penetration depth of human normal bladder tissue at these wavelengths of laser and their linearly polarized laser irradiation also increased with increasing wavelengths. But there were a number of gurgitations. Refractive index of human normal bladder tissue at these wavelengths of laser ranged from 1.37 to 1.44. Absorption coefficient, scattering coefficient, total attenuation coefficient, and effective attenuation coefficients of human normal bladder tissue in Kubelka-Munk two-flux model at the same wavelength of laser and the linearly polarized laser irradiation do not exhibit prominent distinction (P > 0.05). Some absorption coefficient, scattering coefficient, total attenuation coefficient, and effective attenuation coefficient of human normal bladder tissue in Kubelka-Munk two-flux model at different wavelengths of laser and their linearly polarized laser irradiation exhibit obvious distinction.

Humans↗

PubMed2004

[Optical properties of human normal small intestine tissue with theoretical model of optics about biological tissues at Ar+ laser and 532 nm laser and their linearly polarized laser irradiation in vitro].

A double-integrating-spheres system, basic principle of measuring technology of ray radiation, and optical model of biological tissues were used for the study. Optical properties of human normal small intestine tissue at 476.5, 488, 496.5, 514.5 and 532 nm laser and their linearly polarized laser irradiation were studied. The results of measurement showed that the total attenuation coefficient and scattering coefficient of the tissue at these wavelengths of laser and their linearly polarized laser irradiation increased with decreasing wavelengths. And obviously there was a distinction at 514.5 to 532 nm wavelength between lasers and their linearly polarized laser irradiation. Absorption coefficient of tissue at these wavelengths of laser and their linearly polarized laser irradiation increased with decreasing wavelengths. Absorption coefficient of tissue at 514.5 to 532 nm wavelength of laser was obviously decreasing, which was independent of these wavelengths of laser or their linearly polarized laser irradiation. Mean cosine of scattering of tissue at these wavelengths of laser and their linearly polarized laser irradiation also increased with decreasing wavelengths. But penetration depth of tissue at these wavelengths of laser and their linearly polarized laser irradiation also increased with increasing of wavelengths. Refractive index of tissue between these wavelengths of laser was within 1.38 to 1.48. Absorption coefficient, scattering coefficient, total attenuation coefficient, effective attenuation coefficients of tissue in Kubelka-Munk two-flux model at the same wavelength of laser and their linearly polarized laser irradiation showed no prominent distinction (P>0.01). Absorption coefficient, scattering coefficient, total attenuation coefficient, effective attenuation coefficients of tissue in Kubelka-Munk two-flux model at different wavelength of laser and their linearly polarized laser irradiation showed obvious distinction. Optical properties of tissue at 514.5 to 532 nm wavelength of laser exhibited obvious distinction.

Absorption↗

PubMed2004

[Photobleaching properties of GFP expressed in human lung cancer cells].

The characteristic properties of GFP make this protein a good candidate for use as a molecular reporter to monitor patterns of protein localization, gene expression, and intracellular protein trafficking in living cells. In this study, the dicistronic expression vector (pEGFP-C1) was used to be transfected into human lung cancer cell line (ASTC-a-1) and a positive clone which stably expressed GFP in high level was obtained. The results showed that the green fluorescent protein expressed in tumor cells was also photobleached under intense irradiation (-488 nm) and the degree of photobleaching varied with the intensity of the excitation. In order to analyze the effect of low temperature on the fluorescent sample, the photobleaching of tumor cell slice stored at -20 degrees C was observed additionally.

Animals↗

PubMed2003

Enhanced sensitivity and spatial resolution for in vivo imaging with low-level light-emitting probes by use of biocompatible chemical agents.

We describe a technique that uses biocompatible chemical agents to enhance both the sensitivity and the resolution of in vivo imaging with low-level light-emitting probes. We demonstrate experimentally, with chemiluminescence (CL) imaging in vitro as an example, that the detected intensity of CL from treated 3-mm-thick skin tissue is approximately fivefold stronger than that from untreated skin. The spatial resolution correspondingly increases approximately threefold.

Animals↗

PubMed2003

Optical properties of human normal small intestine tissue determined by Kubelka-Munk method in vitro.

AIM: To study the optical properties of human normal small intestine tissue at 476.5 nm, 488 nm, 496.5 nm, 514.5 nm, 532 nm, 808 nm wavelengths of laser irradiation. METHODS: A double-integrating-sphere system, the basic principle of measuring technology of light radiation, and an optical model of biological tissues were used in the study. RESULTS: The results of measurement showed that there were no significant differences in the absorption coefficients of human normal small intestine tissue at 476.5 nm, 488 nm, 496.5 nm laser in the Kubelka-Munk two-flux model (P>0.05). The absorption coefficients of the tissue at 514.5 nm, 532 nm, 808 nm laser irradiation were obviously increased with the decrease of these wavelengths. The scattering coefficients of the tissue at 476.5 nm, 488 nm, 496.5 nm laser irradiation were increased with the decrease of these wavelengths. The scattering coefficients at 496.5 nm, 514.5 nm, 532 nm laser irradiation were obviously increased with the increase of these wavelengths. The scattering coefficient of the tissue at 532 nm laser irradiation was bigger than that at 808 nm. There were no significant differences in the total attenuation coefficient of the tissue at 476.5 nm and 488 nm laser irradiation (P>0.05). The total attenuation coefficient of the tissue at 488 nm, 496.5 nm, 514.5 nm, 532 nm, 808 nm laser irradiation was obviously increased with the decrease of these wavelengths, and their effective attenuation coefficient revealed the same trend. There were no significant differences among the forward scattered photon fluxe, backward scattered photon fluxe, and total scattered photon fluxe of the tissue at 476.5 nm, 488 nm, 496.5 nm laser irradiation. They were all obviously increased with attenuation of tissue thickness. The attenuations of forward and backward scattered photon fluxes, and the total scattered photon fluxe of the tissue at 514.5 nm laser irradiation were slower than those at 476.5 nm, 488 nm, 496.5 nm laser irradiation respectively. The attenuations of forward and backward scattered photon fluxes, and total scattered photon fluxes at 532 nm laser irradiation were obviously slower than those at 476.5 nm, 488 nm, 496.5 nm, 514.5 nm laser irradiation. The attenuations of forward and backward scattered photon fluxes, and total scattered photon fluxe at 808 nm laser irradiation were all obviously slower than those at 476.5 nm, 488 nm, 496.5 nm, 514.5 nm, 532 nm laser irradiation respectively. CONCLUSION: There are significant differences in optical parameters of human normal small intestine tissue in the Kubelka-Munk two-flux model at six different wavelengths of laser radiation. The results would provide a new method of information analysis for clinical diagnosis.

Humans↗