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1.
Z Y Shen  C Q Ye  D C Wu 《Radiation research》1989,120(2):234-250
The alveolar type II cell is one of the critical cells for radiation damage in the lungs after inhalation of radioactive aerosols. With the aid of a Quantimet-970 image analyzer and a VAX-11/780 computer, we calculated the radiation dose to rat alveolar type II cells from alpha particles emitted by 239PuO2. A series of dosimetric parameters for type II cells, including track length distribution, linear energy transfer (LET), values of the specific energy for a single hit of a spherical target (z1), cellular dose, hit number, and their spatial distributions were calculated. By comparing the volume density of type II cells and lung tissue with energy deposited in alveolar type II cells, we found that the energy deposited per unit volume of type II cells was larger than that of lung tissue excluding type II cells. The z1 for spherical targets and the LET across type II cells were less than those in lung tissue excluding type II cells. The age of the rat and damage to lung by inhalation may significantly influence some of the parameters. The neoplastic transformation probability for type II cells is also discussed. The results suggest that the type II cell is an important target cell in the rat lung for exposure to inhaled 239PuO2.  相似文献   

2.
Cell inactivation after exposure to collimated 3.5-MeV alpha particles in three hamster cell lines, V79, CHO-10B, and HS-23, one mouse cell line, C3H 10T1/2, and a human skin fibroblast cell line were studied. Several parameters were investigated for each cell line. Theoretical calculations were performed to find the distribution of energy deposited in the nuclear volume for each cell line. The mean number of alpha-particle traversals required to induce a lethal lesion varied between two for HS-23 cells and six for C3H 10T1/2 cells. The number of traversals per unit area and the total track length of alpha particles that inactivated a cell were found to be nearly constant for the hamster and mouse cell lines. These quantities were found to be lower for the human skin fibroblast cell line. The RBE values for all cell lines were found to be about 3.8 at 10% survival. Thus cell lines that are more sensitive to alpha radiation are also more sensitive to gamma radiation. The average number of alpha-particle traversals producing a single lethal lesion is greater than one. The passages of alpha particles through the cell nucleus that do not kill the cell may lead to carcinogenic effects.  相似文献   

3.
There is strong evidence that biological response to ionizing radiation has a contribution from unirradiated "bystander" cells that respond to signals emitted by irradiated cells. We discuss here an approach incorporating a radiobiological bystander response, superimposed on a direct response due to direct energy deposition in cell nuclei. A quantitative model based on this approach is described for alpha-particle-induced in vitro oncogenic transformation. The model postulates that the oncogenic bystander response is a binary "all or nothing" phenomenon in a small sensitive subpopulation of cells, and that cells from this sensitive subpopulation are also very sensitive to direct hits from alpha particles, generally resulting in a directly hit sensitive cell being inactivated. The model is applied to recent data on in vitro oncogenic transformation produced by broad-beam or microbeam alpha-particle irradiation. Two parameters are used in analyzing the data for transformation frequency. The analysis suggests that, at least for alpha-particle-induced oncogenic transformation, bystander effects are important only at small doses-here below about 0.2 Gy. At still lower doses, bystander effects may dominate the overall response, possibly leading to an underestimation of low-dose risks extrapolated from intermediate doses, where direct effects dominate.  相似文献   

4.
Alpha-particle emitters are currently being evaluated for the treatment of metastatic disease. The dosimetry of alpha-particle emitters is a challenge, however, because the stochastic patterns of energy deposition within cellular targets must be taken into account. We propose a model for the tumor control probability of alpha-particle emitters which takes into account these stochastic effects. An expression for cell survival, which is a function of the microdosimetric single-event specific-energy distribution, is multiplied by the number of cells within the tumor cluster. Poisson statistics is used to model the probability of zero surviving cells within the cluster. Based on this analysis, a number of observations have been made: (1) The dose required to eradicate a tumor is nearly a linear function of the cell survival parameter z(0). (2) Cells with smaller nuclei will require more dose to achieve the same level of tumor control probability, relative to cells with larger nuclei, for an identical source-target configuration and cell sensitivity. (3) As the targeting of alpha-particle emitters becomes more specific, the dose required to achieve a given level of tumor control decreases. (4) Additional secondary effects include cell shape and the initial alpha-particle energy.  相似文献   

5.
Alpha-particle exposures were used to determine whether cells of the human prostate carcinoma cell line DU-145 can produce and respond to a bystander effect signal. An apparatus for alpha-particle irradiation of cells growing as a monolayer on a 1.4-microm-thick Mylar membrane directly above an 241Am alpha-particle source was constructed and calibrated. At the cell irradiation position, the alpha-particle fluence was 998 counts/mm2 s(-1), the average alpha-particle energy was 3.14 MeV, and the average linear energy transfer was 128 keV/microm. The average dose rate to the cells growing on the Mylar surface was 1.2 Gy/min. A co-culture system was used to examine bystander effects transmitted through the medium from the directly targeted cells to tumor cells growing on an insert well beyond the range of the alpha particles. Alpha-particle doses from 0.1 to 6.0 Gy to the targeted cells on the Mylar membrane, followed by a 2-h co-incubation of the cells on the insert in the irradiated medium above the irradiated cells, all caused an approximately 50% increase in micronucleus formation in the nontargeted co-cultured cells. Addition of the radical scavenger DMSO to the medium during the irradiation and the 2-h postirradiation incubation period completely blocked the bystander effect, whereas addition of a nitric oxide scavenger had no effect. Irradiation of medium containing serum, followed by a 2-h incubation, caused no bystander effect in the co-cultured cells. When the co-cultured cells on the insert were placed into the irradiated medium above the directly targeted cells immediately (approximately 1 min) after the irradiation and co-incubated for 2 h, there was no bystander effect. These data indicate that the observed bystander effect requires that the co-cultured cells be present in the medium during the irradiation of the directly targeted cells and suggest the involvement of a short-lived radical species.  相似文献   

6.
Molecular imaging has moved to the forefront of drug development and biomedical research. The identification of appropriate imaging targets has become the touchstone for the accurate diagnosis and prognosis of human cancer. Particularly, cell surface- or membrane-bound proteins are attractive imaging targets for their aberrant expression, easily accessible location, and unique biochemical functions in tumor cells. Previously, we published a literature mining of potential targets for our in-house enzyme-mediated cancer imaging and therapy technology. Here we present a simple and integrated bioinformatics analysis approach that assembles a public cancer microarray database with a pathway knowledge base for ascertaining and prioritizing upregulated genes encoding cell surface- or membrane-bound proteins, which could serve imaging targets. As examples, we obtained lists of potential hits for six common and lethal human tumors in the prostate, breast, lung, colon, ovary, and pancreas. As control tests, a number of well-known cancer imaging targets were detected and confirmed by our study. Further, by consulting gene-disease and protein-disease databases, we suggest a number of significantly upregulated genes as promising imaging targets, including cell surface-associated mucin-1, prostate-specific membrane antigen, hepsin, urokinase plasminogen activator receptor, and folate receptors. By integrating pathway analysis, we are able to organize and map "focused" interaction networks derived from significantly dysregulated entity pairs to reflect important cellular functions in disease processes. We provide herein an example of identifying a tumor cell growth and proliferation subnetwork for prostate cancer. This systematic mining approach can be broadly applied to identify imaging or therapeutic targets for other human diseases.  相似文献   

7.
We analyzed transmission electron micrographs of human lung mast cells by digitized planimetry and point counting to determine the cross-sectional areas of two distinct cytoplasmic organelles: specific granules and lipid bodies. Specific granules have a limiting membrane and often contain one or more cylindrical scroll-like inclusions. By contrast, lipid bodies are on average much larger than granules and lack both limiting membranes and inclusions. The measured cross-sectional areas of lipid bodies and scroll-containing granules were converted to equivalent volumes, and the noise in the frequency distribution of these volumes was smoothed using a moving bin technique. This analysis revealed (a) a periodic, multimodal distribution of granule equivalent volumes in which the modes fell at volumes that were integral multiples of the volume defined by the first mode (the "unit volume"), and (b) a modal granule equivalent volume frequency that occurred at a magnitude equal to four "unit volumes." Thus, specific granules appear to be composed of units of a narrowly fixed volume. Furthermore, the mean volume of intragranule inclusions was 0.0061 mu3, a value very similar to that calculated for the "unit volume" (0.0071 mu3). This result suggests that each "unit volume" comprising the individual scroll-type granules contains (or is capable of generating or accommodating) a single scroll-like inclusion. In contrast to the specific granules, mast cell lipid bodies lack a periodic, multimodal volume distribution. Taken together, these findings suggest that the volumes of human lung mast cell granules and lipid bodies are regulated by distinct mechanisms.  相似文献   

8.
Mechanism of Action of Nalidixic Acid on Conjugating Bacteria   总被引:8,自引:5,他引:3       下载免费PDF全文
When nalidixic acid, a specific and effective inhibitor of cellular deoxyribonucleic acid synthesis, is added to conjugating bacteria at any time during mating, it stops genetic transfer provided the donor bacterium is sensitive to the drug. When this inhibition is released by the removal of the nalidixic acid, transfer does not resume at the point on the chromosome where it was stopped, but begins again at the transfer origin. Curves relating the effects of various low doses of nalidixic acid to the frequency of recombination reveal that several "hits" are necessary to inhibit recombination for early markers. The number of required "hits" decreases as the distance of the marker from the transfer origin increases. Transfer between drug-resistant cells may also be inhibited by nalidixic acid. The effect of high drug doses on matings between resistant cells is similar to that of low drug doses on matings with a sensitive male.  相似文献   

9.
Plutonium is not uniformly distributed in testicular tissues; thus some cell populations may receive larger or smaller radiation exposures than would be expected if the nuclide were uniformly distributed. The distributions of cell populations within alpha-particle range of Pu deposits in rat and beagle testes were determined. The data were collected from autoradiographs of testicular tissues containing 241Pu. A cell distribution factor (CDF) was determined for each cell population and is defined as the average number of each cell type within alpha-particle range of each observed Pu deposit relative to the number of each cell type that would be expected within alpha-particle range of each Pu deposit, if the deposits were distributed uniformly. In addition, the percentage of the spermatogonial stem cell population within alpha-particle range of Pu deposits was determined. In rats, the CDF for the spermatogonial stem cells is about 2.2. This value is similar to other enhancement and inhomogeneity factors reported for rodents in the literature. In beagles the CDFs to all cells in the seminiferous epithelium were less than the rats. In addition, the percentage of spermatogonial cells within alpha-particle range of Pu concentrations in the interstitial tissues was a factor of about 3 less in the dog than in the rat. The largest CDFs seen in both species were in the interstitial tissues, particularly for Leydig cells. Because the organization of testicular tissues in the beagle is quite different from rodents but more similar to human, the results from this study suggest that extrapolations from rodents to humans may tend to overestimate the potential for radiation exposure to spermatogonial stem cells as well as the fraction of the spermatogonial stem cell population at risk to exposure from internally deposited 239Pu.  相似文献   

10.
Complex chromosome aberrations (any exchange involving three or more breaks in two or more chromosomes) are effectively induced in peripheral blood lymphocytes (PBL) after exposure to low doses (mostly single particles) of densely ionising high-linear energy transfer (LET) alpha-particle radiation. The complexity, when observed by multiplex fluorescence in situ hybridisation (m-FISH), shows that commonly four but up to eight different chromosomes can be involved in each rearrangement. Given the territorial organisation of chromosomes in interphase and that only a very small fraction of the nucleus is irradiated by each alpha-particle traversal, the aim of this study is to address how aberrations of such complexity can be formed. To do this, we applied theoretical "cycle" analyses using m-FISH paint detail of PBL in their first cell division after exposure to high-LET alpha-particles. In brief, "cycle" analysis deconstructs the aberration "observed" by m-FISH to make predictions as to how it could have been formed in interphase. We propose from this that individual high-LET alpha-particle-induced complex aberrations may be formed by the misrepair of damaged chromatin in single physical "sites" within the nucleus, where each "site" is consistent with an "area" corresponding to the interface of two to three different chromosome territories. Limited migration of damaged chromatin is "allowed" within this "area". Complex aberrations of increased size, reflecting the path of alpha-particle nuclear intersection, are formed through the sequential linking of these individual sites by the involvement of common chromosomes.  相似文献   

11.
The effects of injected short-, medium- and longer-range alpha-particle emitters ((149)Tb, (211)At/(211)Po and (213)Bi/(213)Po, respectively) on the total hemopoietic stem cell population of active normal bone marrow in humans of various ages has been estimated using Monte Carlo modeling. The fraction of the normal hemopoietic stem cells that are hit and survive has been calculated as a first step toward estimating the risk of development of therapy-induced leukemia. The fraction was lowest for the shorter-range alpha-particle emitter ((149)Tb) and highest for the longer-range alpha-particle emitter ((213)Bi/(213)Po), with the value for the medium-range alpha-particle emitter (211)At/(211)Po being intermediate between these. There was little variation in the data with the age of the subject within each alpha-particle emitter. This lack of age dependence provides reassurance that the fraction of cells hit in any subject of any age with normal marrow can be estimated by modeling newborn marrow (which requires little computing time) despite age-related differences in microarchitecture.  相似文献   

12.
Intercellular variations in the level of antigen expression and in cellular and nuclear radii were taken into account in a model used to estimate cell survival for an in vitro experiment with antibodies containing alpha-particle emitters that target the cell surface. Using measured variations in these characteristics for cells of two human cancer cell lines, the model gave results for cell survival and the fundamental parameter of radiation sensitivity, z(0), that differ substantially from those obtained using only mean values. The cell survival may be underestimated by a factor of 100 if only mean values of these cellular parameters are used, and calculated values of z(0) may be overestimated by a factor of 2. Most of this effect stems from the variation in antigen expression. The magnitudes of the differences were found to be a function of the fractions of mean specific energy delivered by surrounding activity and by activity bound to the cells.  相似文献   

13.
Accelerated helium ions with mean energies at the target location of 3-7 MeV were used to simulate alpha-particle radiation from radon daughters. The experimental setup and calibration procedure allowed determination of the helium-ion energy distribution and dose in the nuclei of irradiated cells. Using this system, the induction of DNA double-strand breaks and their spatial distributions along DNA were studied in irradiated human fibroblasts. It was found that the apparent number of double-strand breaks as measured by a standard pulsed-field gel assay (FAR assay) decreased with increasing LET in the range 67-120 keV/microm (corresponding to the energy of 7-3 MeV). On the other hand, the generation of small and intermediate-size DNA fragments (0.1-100 kbp) increased with LET, indicating an increased intratrack long-range clustering of breaks. The fragment size distribution was measured in several size classes down to the smallest class of 0.1-2 kbp. When the clustering was taken into account, the actual number of DNA double-strand breaks (separated by at least 0.1 kbp) could be calculated and was found to be in the range 0.010-0.012 breaks/Mbp Gy(-1). This is two- to threefold higher than the apparent yield obtained by the FAR assay. The measured yield of double-strand breaks as a function of LET is compared with theoretical Monte Carlo calculations that simulate the track structure of energy depositions from helium ions as they interact with the 30-nm chromatin fiber. When the calculation is performed to include fragments larger than 0.1 kbp (to correspond to the experimental measurements), there is good agreement between experiment and theory.  相似文献   

14.
Lipids play a central role in lung physiology and pathology; however, a comprehensive lipidomic characterization of human pulmonary cells relevant to disease has not been performed. The cells involved in lung host defense, including alveolar macrophages (AMs), bronchial epithelial cells (BECs), and alveolar type II cells (ATIIs), were isolated from human subjects and lipidomic analysis by LC-MS and LC-MS/MS was performed. Additionally, pieces of lung tissue from the same donors were analyzed by MALDI imaging MS in order to determine lipid localization in the tissue. The unique distribution of phospholipids in ATIIs, BECs, and AMs from human subjects was accomplished by subjecting the large number of identified phospholipid molecular species to univariant statistical analysis. Specific MALDI images were generated based on the univariant statistical analysis data to reveal the location of specific cell types within the human lung slice. While the complex composition and function of the lipidome in various disease states is currently poorly understood, this method could be useful for the characterization of lipid alterations in pulmonary disease and may aid in a better understanding of disease pathogenesis.  相似文献   

15.
The vascular transfer cells in garlic scape havebeen examined with electron microscope. Their structure, distributive feature and adenosine triphosphatase (ATPase) activity are studied. The mature vascular transfer cells exhibit the characteristic cell wall ingrowths. The cell contents include a large nucleus, dense cytoplasm and various normal organelles. It is notable that there are numerous mitochondria with well developed, cristae. Plasmodesmata are extensively present in the wall, and transfer cells are connected to adjacent cells by them. The senescing transfer cells become more vacuolated and have a large central vacuole and dense parietal cytoplasm. Their wall ingrowths seem to degenerate and finally disappear. The transfer cells show a particular pattern of distribution in the vascular bundle of the garlic scape. Some of them are present between the vessels of xylem and the sieve tubes of phloem. However, more abundant cell wall ingrowths occur on those walls which abut on, or are close to the vessel of xylem. The other transfer cells are located between the sieve tubes and parenehyma cells. The phloem transfer cell which is adjacent to sieve tube has developed from companion cell. All the transfer cells are mainly concerned with the loading and unloading of sieve tubes. And they may play an important role in facilitating intensive material transfer between two independent systems (i.e. the vessels and sieve tubes, the symplast and apoplast). The results of the cytochemical localization of ATPase using a lead precipitation technique exhibit strong enzyme activity on the plasmalemma of the transfer cells. It is suggested that the transfer cells are especially active in solute movement through them to which cellular energy metabolism coupled.  相似文献   

16.
A new experimental setup for uniform alpha-particle irradiation of cells in vitro is described. The alpha-particle irradiator is based on a radioactive (212)Pb/(212)Bi source. In the experimental setup proposed, cells are grown directly on a polylysine-coated track-etch material that forms the base of custom-made cell dishes. Alpha-particle irradiation is done through the base of the dish. Immediately prior to irradiation, the cell dish is scanned under a microscope, and images of cells with the corresponding coordinates are saved. After irradiation and after the biological end point under study has been determined, the cell dish is etched to develop alpha-particle tracks in the dish base. A microscope image series of alpha-particle track images is obtained by accurately revisiting every original (preirradiation) cell position in the track-etched dish. The number of alpha-particle traversals of each individual cell is scored by mapping images of alpha-particle tracks onto the images of cells recorded prior to irradiation. The uncertainty of the alpha-particle hit determination is 0.9 microm. The procedure described thus presents a method for radiobiological experiments with absolute, rather than statistical, cell dosimetry.  相似文献   

17.
While pharmacological inhibition of Akt kinase has been regarded as a promising anti-cancer strategy, most of the Akt inhibitors that have been developed are enzymatic inhibitors that target the kinase active site of Akt. Another key cellular regulatory event for Akt activation is the translocation of Akt kinase to the cell membrane from the cytoplasm, which is accomplished through the pleckstrin homology (PH) domain of Akt. However, compounds specifically interacting with the PH domain of Akt to inhibit Akt activation are currently limited. Here we identified a compound, lancemaside A (LAN-A), which specifically binds to the PH domain of Akt kinase. First, our mass spectra analysis of cellular Akt kinase isolated from cells treated with LAN-A revealed that LAN-A specifically binds to the PH domain of cellular Akt kinase. Second, we observed that LAN-A inhibits the translocation of Akt kinase to the membrane and thus Akt activation, as examined by the phosphorylation of various downstream targets of Akt such as GSK3β, mTOR and BAD. Third, in a co-cultured cell model containing human lung epithelial cancer cells (A549) and normal human primary lung fibroblasts, LAN-A specifically restricts the growth of the A549 cells. LAN-A also displayed anti-proliferative effects on various human cancer cell lines. Finally, in the A549-luciferase mouse transplant model, LAN-A effectively inhibited A549 cell growth with little evident cytotoxicity. Indeed, the therapeutic index of LAN-A in this mouse model was >250, supporting that LAN-A is a potential lead compound for PH domain targeting as a safe anti-cancer Akt inhibitor.  相似文献   

18.
The degree of nonuniform distribution of plutonium in the human lung has not been determined; thus current dosimetric models do not account for nonuniform irradiation. A better scientific basis is needed for assessing the risk of developing radiation-induced disease from inhaled alpha-particle-emitting radionuclides. We measured the distribution of plutonium activity in the lung by autoradiography and related the activity to specific compartments of the lung. The study materials were lung specimens from deceased workers employed by the Mayak Production Association. The approach to analyzing these lung samples used contemporary stereological sampling and analysis techniques together with quantitative alpha-particle autoradiography. For the first time, plutonium distribution has been quantified in the human lung. The distribution of long-term retained plutonium is nonuniform, and a significant portion of plutonium was retained in pulmonary scars. In addition, a large fraction of plutonium was present in the parenchyma, where it was retained much longer than was estimated previously. The sequestration of plutonium particles in scars would greatly reduce the radiation exposure of the critical target cells and tissues for lung cancer. Thus the prolonged retention of plutonium in lung scars may not increase the dose or risk for lung cancer.  相似文献   

19.
Matrix metalloproteinase-9 (MMP-9) is a significant target for the development of drugs for the treatment of arthritis, CNS disorders, and cancer metastasis. The structure-based and ligand-based methods were used for the virtual screening (VS) of database compounds to obtain potent and selective MMP-9 inhibitors. Experimentally known MMP-9 inhibitors were used to grow up ligand-based three pharmacophore models utilizing Schrodinger suite. The X-ray crystallographic structures of MMP-9 with different inhibitors were used to develop five energy-optimized structure-based (e-pharmacophore) models. All developed pharmacophores were validated and applied to screen the Zinc database. Pharmacophore matched compounds were subjected to molecular docking to retrieve hits with novel scaffolds. The molecules with diverse structures, high docking scores and low binding energies for various crystal structures of MMP-9, were selected as final hits. The Induced fit docking (IFD) analysis provided significant information about the driving of inhibitor to approve a suitable bioactive conformational position in the active site of protein. Since charge transfer reaction occurs during receptor–ligand interaction, therefore, electronic features of hits (ligands) are interesting parameters to explain the binding interactions. Density functional theory (DFT) at B3LYP/6-31G* level was utilized to explore electronic features of hits. The docking study of hits using AutoDock was helpful to establish the binding interactions. The study illustrates that the combined pharmacophore approach is advantageous to identify diverse hits which have better binding affinity to the active site of the enzyme for all possible bioactive conformations. The approach used in the study is worthy to design drugs for other targets.  相似文献   

20.
Tumor angiogenesis plays essential roles during lung cancer progression and metastasis. Therapeutic agent that targets both tumor cell and vascular endothelial cell may achieve additional anti-tumor efficacy. We demonstrate that bedaquiline, a FDA-approved antibiotic drug, effectively targets lung cancer cells and angiogenesis. Bedaquiline dose-dependently inhibits proliferation and induces apoptosis of a panel of lung cancer cell lines regardless of subtypes and molecular heterogeneity. Bedaquiline also inhibits capillary network formation of human lung tumor associated-endothelial cell (HLT-EC) on Matrigel and its multiple functions, such as spreading, proliferation and apoptosis, even in the presence of vascular endothelial growth factor (VEGF). We further demonstrate that bedaquiline acts on lung cancer cells and HLT-EC via inhibiting mitochondrial respiration and glycolysis, leading to ATP reduction and oxidative stress. Consistently, oxidative damage on DNA, protein and lipid were detected in cells exposed to bedaquiline. Importantly, the results obtained in in vitro cell culture are reproducible in in vivo xenograft lung cancer mouse model, confirming that bedaquiline suppresses lug tumor growth and angiogenesis, and increases oxidative stress. Our findings demonstrating that energy depletion is effectively against lung tumor cells and angiogenesis. Our work also provide pre-clinical evidence to repurpose antibiotic bedaquiline for lung cancer treatment.  相似文献   

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