scholarly journals Relationship of In Vitro Toxicity of Technetium-99m to Subcellular Localisation and Absorbed Dose

2021 ◽  
Vol 22 (24) ◽  
pp. 13466
Author(s):  
Ines M. Costa ◽  
Noor Siksek ◽  
Alessia Volpe ◽  
Francis Man ◽  
Katarzyna M. Osytek ◽  
...  
Keyword(s):  
Dna Damage ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Absorbed Dose ◽  
In Vitro Toxicity ◽  
Subcellular Localisation ◽  
Protein Fusion ◽  
External Beam Irradiation ◽  
Technetium 99M

Auger electron-emitters increasingly attract attention as potential radionuclides for molecular radionuclide therapy in oncology. The radionuclide technetium-99m is widely used for imaging; however, its potential as a therapeutic radionuclide has not yet been fully assessed. We used MDA-MB-231 breast cancer cells engineered to express the human sodium iodide symporter-green fluorescent protein fusion reporter (hNIS-GFP; MDA-MB-231.hNIS-GFP) as a model for controlled cellular radionuclide uptake. Uptake, efflux, and subcellular location of the NIS radiotracer [99mTc]TcO4− were characterised to calculate the nuclear-absorbed dose using Medical Internal Radiation Dose formalism. Radiotoxicity was determined using clonogenic and γ-H2AX assays. The daughter radionuclide technetium-99 or external beam irradiation therapy (EBRT) served as controls. [99mTc]TcO4− in vivo biodistribution in MDA-MB-231.hNIS-GFP tumour-bearing mice was determined by imaging and complemented by ex vivo tissue radioactivity analysis. [99mTc]TcO4− resulted in substantial DNA damage and reduction in the survival fraction (SF) following 24 h incubation in hNIS-expressing cells only. We found that 24,430 decays/cell (30 mBq/cell) were required to achieve SF0.37 (95%-confidence interval = [SF0.31; SF0.43]). Different approaches for determining the subcellular localisation of [99mTc]TcO4− led to SF0.37 nuclear-absorbed doses ranging from 0.33 to 11.7 Gy. In comparison, EBRT of MDA-MB-231.hNIS-GFP cells resulted in an SF0.37 of 2.59 Gy. In vivo retention of [99mTc]TcO4− after 24 h remained high at 28.0% ± 4.5% of the administered activity/gram tissue in MDA-MB-231.hNIS-GFP tumours. [99mTc]TcO4− caused DNA damage and reduced clonogenicity in this model, but only when the radioisotope was taken up into the cells. This data guides the safe use of technetium-99m during imaging and potential future therapeutic applications.

scholarly journals Effects of wound dressings containing silver on skin and immune cells

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kristina Nešporová ◽  
Vojtěch Pavlík ◽  
Barbora Šafránková ◽  
Hana Vágnerová ◽  
Pavel Odráška ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ex Vivo ◽  
Wound Dressings ◽  
In Vitro Toxicity ◽  
Skin Cells ◽  
Antimicrobial Efficiency ◽  
Activated Neutrophils ◽  
Stress Related Genes

Abstract Wound dressings with silver have been shown to be cytotoxic in vitro. However, the extrapolation of this cytotoxicity to clinical settings is unclear. We applied dressings with various forms of silver on porcine skin ex vivo and investigated silver penetration and DNA damage. We assessed antimicrobial efficacy, cytotoxicity to skin cells, and immune response induced by the dressings. All dressings elevated the DNA damage marker γ-H2AX and the expression of stress-related genes in explanted skin relative to control. This corresponded with the amount of silver in the skin. The dressings reduced viability, induced oxidative stress and DNA damage in skin cells, and induced the production of pro-inflammatory IL-6 by monocytes. The oxidative burst and viability of activated neutrophils decreased. The amount of silver released into the culture medium varied among the dressings and correlated with in vitro toxicity. However, antimicrobial efficiencies did not correlate strongly with the amount of silver released from the dressings. Antimicrobial efficiency and toxicity are driven by the form of silver and the construction of dressings and not only by the silver concentration. The damaging effects of silver dressings in ex vivo skin highlight the importance of thorough in vivo investigation of silver dressing toxicity.

Cytogenetic Damage of Human Lymphocytes in Humanized Mice Exposed to Neutrons and X Rays 24 h After Exposure

2021 ◽  
Vol 161 (6-7) ◽  
pp. 352-361
Author(s):  
Qi Wang ◽  
Younghyun Lee ◽  
Monica Pujol-Canadell ◽  
Jay R. Perrier ◽  
Lubomir Smilenov ◽  
...  
Keyword(s):  
Dna Damage ◽  
Radiation Exposure ◽  
Human Lymphocytes ◽  
Absorbed Dose ◽  
Chromosome 1 ◽  
X Rays ◽  
Chromosomal Dna ◽  
Humanized Mouse Model ◽  
Significant Difference

Detonation of an improvised nuclear device highlights the need to understand the risk of mixed radiation exposure as prompt radiation exposure could produce significant neutron and gamma exposures. Although the neutron component may be a relatively small percentage of the total absorbed dose, the large relative biological effectiveness (RBE) can induce larger biological DNA damage and cell killing. The objective of this study was to use a hematopoietically humanized mouse model to measure chromosomal DNA damage in human lymphocytes 24 h after in vivo exposure to neutrons (0.3 Gy) and X rays (1 Gy). The human dicentric and cytokinesis-block micronucleus assays were performed to measure chromosomal aberrations in human lymphocytes in vivo from the blood and spleen, respectively. The mBAND assay based on fluorescent in situ hybridization labeling was used to detect neutron-induced chromosome 1 inversions in the blood lymphocytes of the neutron-irradiated mice. Cytogenetics endpoints, dicentrics and micronuclei showed that there was no significant difference in yields between the 2 irradiation types at the doses tested, indicating that neutron-induced chromosomal DNA damage in vivo was more biologically effective (RBE ∼3.3) compared to X rays. The mBAND assay, which is considered a specific biomarker of high-LET neutron exposure, confirmed the presence of clustered DNA damage in the neutron-irradiated mice but not in the X-irradiated mice, 24 h after exposure.

Apoptosis and DNA damage in type 2 alveolar epithelial cells cultured from hyperoxic rats

1998 ◽  
Vol 274 (5) ◽  
pp. L714-L720 ◽  
Author(s):  
Sue Buckley ◽  
Lora Barsky ◽  
Barbara Driscoll ◽  
Kenneth Weinberg ◽  
Kathryn D. Anderson ◽  
...  
Keyword(s):  
Dna Damage ◽  
Epithelial Cells ◽  
Cellular Response ◽  
Ex Vivo ◽  
Keratinocyte Growth Factor ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Dna Laddering

Apoptosis is a genetically controlled cellular response to developmental stimuli and environmental insult that culminates in cell death. Sublethal hyperoxic injury in rodents is characterized by a complex but reproducible pattern of lung injury and repair during which the alveolar surface is damaged, denuded, and finally repopulated by type 2 alveolar epithelial cells (AEC2). Postulating that apoptosis might occur in AEC2 after hyperoxic injury, we looked for the hallmarks of apoptosis in AEC2 from hyperoxic rats. A pattern of increased DNA end labeling, DNA laddering, and induction of p53, p21, and Bax proteins, strongly suggestive of apoptosis, was seen in AEC2 cultured from hyperoxic rats when compared with control AEC2. In contrast, significant apoptosis was not detected in freshly isolated AEC2 from oxygen-treated rats. Thus the basal culture conditions appeared to be insufficient to ensure the ex vivo survival of AEC2 damaged in vivo. The oxygen-induced DNA strand breaks were blocked by the addition of 20 ng/ml of keratinocyte growth factor (KGF) to the culture medium from the time of plating and were partly inhibited by Matrigel or a soluble extract of Matrigel. KGF treatment resulted in a partial reduction in the expression of the p21, p53, and Bax proteins but had no effect on DNA laddering. We conclude that sublethal doses of oxygen in vivo cause damage to AEC2, resulting in apoptosis in ex vivo culture, and that KGF can reduce the oxygen-induced DNA damage. We speculate that KGF plays a role as a survival factor in AEC2 by limiting apoptosis in the lung after acute hyperoxic injury.

scholarly journals OASTL-A1 functions as a cytosolic cysteine synthase and affects arsenic tolerance in rice

2020 ◽  
Vol 71 (12) ◽  
pp. 3678-3689 ◽  
Author(s):  
Chengcheng Wang ◽  
Lihua Zheng ◽  
Zhong Tang ◽  
Shengkai Sun ◽  
Jian Feng Ma ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Tissue Expression ◽  
Protein Fusion ◽  
Outer Cortex ◽  
Cysteine Synthase ◽  
Arsenic Tolerance ◽  
Tissue Expression Analysis ◽  
Green Fluorescent

Abstract Arsenic (As) contamination in paddy soil can cause phytotoxicity and elevated As accumulation in rice grains. Arsenic detoxification is closely linked to sulfur assimilation, but the genes involved have not been described in rice. In this study, we characterize the function of OASTL-A1, an O-acetylserine(thiol) lyase, in cysteine biosynthesis and detoxification of As in rice. Tissue expression analysis revealed that OsOASTL-A1 is mainly expressed in roots at the vegetative growth stage and in nodes at the reproductive stage. Furthermore, the expression of OsOASTL-A1 in roots was strongly induced by As exposure. Transgenic rice plants expressing pOsOASTL-A1::GUS (β-glucuronidase) indicated that OsOASTL-A1 was strongly expressed in the outer cortex and the vascular cylinder in the root mature zone. Subcellular localization using OsOASTL-A1:eGFP (enhanced green fluorescent protein) fusion protein showed that OsOASTL-A1 was localized to the cytosol. In vivo and in vitro enzyme activity assays showed that OsOASTL-A1 possessed the O-acetylserine(thiol) lyase activity. Knockout of OsOASTL-A1 led to significantly lower levels of cysteine, glutathione, and phytochelatins in roots and increased sensitivity to arsenate stress. Furthermore, the osoastl-a1 knockout mutants reduced As accumulation in the roots, but increased As accumulation in shoots. We conclude that OsOASTL-A1 is the cytosolic O-acetylserine(thiol) lyase that plays an important role in non-protein thiol biosynthesis in roots for As detoxification.

scholarly journals DNA Damage in Blood Leukocytes of Prostate Cancer Patients Undergoing PET/CT Examinations with [68Ga]Ga-PSMA I&T

Cancers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 388 ◽  
Author(s):  
Sarah Schumann ◽  
Harry Scherthan ◽  
Torsten Frank ◽  
Constantin Lapa ◽  
Jessica Müller ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Ex Vivo ◽  
Absorbed Dose ◽  
Dna Double Strand Breaks ◽  
Blood Leukocytes ◽  
Blood Samples ◽  
Time Points ◽  
Pet Ct ◽  
Radiation Induced

The aim was to investigate the induction and repair of radiation-induced DNA double-strand breaks (DSBs) as a function of the absorbed dose to the blood of patients undergoing PET/CT examinations with [68Ga]Ga-PSMA. Blood samples were collected from 15 patients before and at four time points after [68Ga]Ga-PSMA administration, both before and after the PET/CT scan. Absorbed doses to the blood were calculated. In addition, blood samples with/without contrast agent from five volunteers were irradiated ex vivo by CT while measuring the absorbed dose. Leukocytes were isolated, fixed, and stained for co-localizing γ-H2AX+53BP1 DSB foci that were enumerated manually. In vivo, a significant increase in γ-H2AX+53BP1 foci compared to baseline was observed at all time points after administration, although the absorbed dose to the blood by 68Ga was below 4 mGy. Ex vivo, the increase in radiation-induced foci depended on the absorbed dose and the presence of contrast agent, which could have caused a dose enhancement. The CT-dose contribution for the patients was estimated at about 12 mGy using the ex vivo calibration. The additional number of DSB foci induced by CT, however, was comparable to the one induced by 68Ga. The significantly increased foci numbers after [68Ga]Ga-PSMA administration may suggest a possible low-dose hypersensitivity.

scholarly journals The in vivo mechanics of the magnetotactic backbone as revealed by correlative FLIM-FRET and STED microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Erika Günther ◽  
André Klauß ◽  
Mauricio Toro-Nahuelpan ◽  
Dirk Schüler ◽  
Carsten Hille ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Living Cells ◽  
Stimulated Emission ◽  
Fluorescence Lifetime Imaging ◽  
Sted Microscopy

AbstractProtein interaction and protein imaging strongly benefit from the advancements in time-resolved and superresolution fluorescence microscopic techniques. However, the techniques were typically applied separately and ex vivo because of technical challenges and the absence of suitable fluorescent protein pairs. Here, we show correlative in vivo fluorescence lifetime imaging microscopy Förster resonance energy transfer (FLIM-FRET) and stimulated emission depletion (STED) microscopy to unravel protein mechanics and structure in living cells. We use magnetotactic bacteria as a model system where two proteins, MamJ and MamK, are used to assemble magnetic particles called magnetosomes. The filament polymerizes out of MamK and the magnetosomes are connected via the linker MamJ. Our system reveals that bacterial filamentous structures are more fragile than the connection of biomineralized particles to this filament. More importantly, we anticipate the technique to find wide applicability for the study and quantification of biological processes in living cells and at high resolution.

scholarly journals Saccharomyces cerevisiae Nip7p is required for efficient 60S ribosome subunit biogenesis.

1997 ◽  
Vol 17 (9) ◽  
pp. 5001-5015 ◽  
Author(s):  
N I Zanchin ◽  
P Roberts ◽  
A DeSilva ◽  
F Sherman ◽  
D S Goldfarb
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fluorescent Protein ◽  
Open Reading Frames ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Protein Fusion ◽  
Acid Protein ◽  
Conserved Gene ◽  
Green Fluorescent

The Saccharomyces cerevisiae temperature-sensitive (ts) allele nip7-1 exhibits phenotypes associated with defects in the translation apparatus, including hypersensitivity to paromomycin and accumulation of halfmer polysomes. The cloned NIP7+ gene complemented the nip7-1 ts growth defect, the paromomycin hypersensitivity, and the halfmer defect. NIP7 encodes a 181-amino-acid protein (21 kDa) with homology to predicted products of open reading frames from humans, Caenorhabditis elegans, and Arabidopsis thaliana, indicating that Nip7p function is evolutionarily conserved. Gene disruption analysis demonstrated that NIP7 is essential for growth. A fraction of Nip7p cosedimented through sucrose gradients with free 60S ribosomal subunits but not with 80S monosomes or polysomal ribosomes, indicating that it is not a ribosomal protein. Nip7p was found evenly distributed throughout the cytoplasm and nucleus by indirect immunofluorescence; however, in vivo localization of a Nip7p-green fluorescent protein fusion protein revealed that a significant amount of Nip7p is present inside the nucleus, most probably in the nucleolus. Depletion of Nip7-1p resulted in a decrease in protein synthesis rates, accumulation of halfmers, reduced levels of 60S subunits, and, ultimately, cessation of growth. Nip7-1p-depleted cells showed defective pre-rRNA processing, including accumulation of the 35S rRNA precursor, presence of a 23S aberrant precursor, decreased 20S pre-rRNA levels, and accumulation of 27S pre-rRNA. Delayed processing of 27S pre-rRNA appeared to be the cause of reduced synthesis of 25S rRNA relative to 18S rRNA, which may be responsible for the deficit of 60S subunits in these cells.

scholarly journals Fluorescently Tagged Potato virus Y: A Versatile Tool for Functional Analysis of Plant-Virus Interactions

2015 ◽  
Vol 28 (7) ◽  
pp. 739-750 ◽  
Author(s):  
Matevz Rupar ◽  
Florence Faurez ◽  
Michel Tribodet ◽  
Ion Gutiérrez-Aguirre ◽  
Agnès Delaunay ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Potato Virus ◽  
Plant Virus ◽  
Potato Virus Y ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Cell Movement ◽  
Long Distance ◽  
Green Fluorescent

Potato virus Y (PVY) is an economically important plant virus that infects Solanaceous crops such as tobacco and potato. To date, studies into the localization and movement of PVY in plants have been limited to detection of viral RNA or proteins ex vivo. Here, a PVY N605 isolate was tagged with green fluorescent protein (GFP), characterized and used for in vivo tracking. In Nicotiana tabacum cv. Xanthi, PVY N605-GFP was biologically comparable to nontagged PVY N605, stable through three plant-to-plant passages and persisted for four months in infected plants. GFP was detected before symptoms and fluorescence intensity correlated with PVY RNA concentrations. PVY N605-GFP provided in vivo tracking of long-distance movement, allowing estimation of the cell-to-cell movement rate of PVY in N. tabacum cv. Xanthi (7.1 ± 1.5 cells per hour). PVY N605-GFP was adequately stable in Solanum tuberosum cvs. Désirée and NahG-Désirée and able to infect S. tuberosum cvs. Bintje and Bea, Nicotiana benthamiana, and wild potato relatives. PVY N605-GFP is therefore a powerful tool for future studies of PVY-host interactions, such as functional analysis of viral and plant genes involved in viral movement.

Gene Transfer in Dendritic Cells, Induced by Oral DNA Vaccination With Salmonellatyphimurium, Results in Protective Immunity Against a Murine Fibrosarcoma

Blood ◽  
1998 ◽  
Vol 92 (9) ◽  
pp. 3172-3176 ◽  
Author(s):  
Paola Paglia ◽  
Eva Medina ◽  
Ivano Arioli ◽  
Carlos A. Guzman ◽  
Mario P. Colombo
Keyword(s):  
Dendritic Cells ◽  
Gene Transfer ◽  
Fluorescent Protein ◽  
Ex Vivo ◽  
Auxotrophic Mutant ◽  
Dna Vaccination ◽  
Target Antigen ◽  
Cmv Promoter ◽  
Murine Fibrosarcoma

A live attenuated AroA− auxotrophic mutant ofSalmonella typhimurium (SL7207) has been used as carrier for the pCMVβ vector that contains the β-galactosidase (β-gal) gene under the control of the immediate early promoter ofCytomegalovirus (CMV). We tested whether orally administered bacterial carrier could enter and deliver the transgene to antigen-presenting cells (APCs) through the natural enteric route of infection and whether β-gal expression could generate a protective response against an aggressive murine fibrosarcoma transduced with the β-gal gene (F1.A11) that behaves operationally as a tumor-associated antigen. After three courses, at 15-day intervals, mice developed both cell-mediated and systemic humoral responses to β-gal. Mice vaccinated with the Salmonella harboring pCMVβ, but not with plasmid-less carrier, showed resistance to a challenge with F1.A11 cells. These experiments suggest that Salmonella-based DNA immunization allows us to specifically target antigen expression in vivo to APCs. To prove that the transgene is actually expressed by APCs as a function of an eukaryotic promoter, the green fluorescent protein (GFP) was placed under the control of either the eukariotic CMV or a prokaryotic promoter. Using cytofluorometric analysis, GFP was detected only in splenocytes of mice receiving a Salmonella carrier harboring GFP under the CMV promoter. These results indicate that transgene expression occurs because of a Salmonella-mediated gene transfer to eukaryotic cells. Finally, approximately 19% of the splenocytes expressed GFP. Among them, F4/80+ macrophages and CD11cbright dendritic cells (DCs) were scored as positive for GFP expression. Extensive work has been performed trying to optimize the way to transfect DCs, ex vivo, with genes coding for relevant antigens. We show here, for the first time, that DCs can be directly and specifically transduced in vivo such to induce DNA vaccination against tumors. © 1998 by The American Society of Hematology.

scholarly journals Recruitment of the Nucleotide Excision Repair Endonuclease XPG to Sites of UV-Induced DNA Damage Depends on Functional TFIIH

2006 ◽  
Vol 26 (23) ◽  
pp. 8868-8879 ◽  
Author(s):  
Angelika Zotter ◽  
Martijn S. Luijsterburg ◽  
Daniël O. Warmerdam ◽  
Shehu Ibrahim ◽  
Alex Nigg ◽  
...  
Keyword(s):  
Dna Damage ◽  
Nucleotide Excision Repair ◽  
Fluorescent Protein ◽  
Core Protein ◽  
Excision Repair ◽  
Mammalian Cell Lines ◽  
Nucleotide Excision ◽  
Green Fluorescent ◽  
Damaged Dna

ABSTRACT The structure-specific endonuclease XPG is an indispensable core protein of the nucleotide excision repair (NER) machinery. XPG cleaves the DNA strand at the 3′ side of the DNA damage. XPG binding stabilizes the NER preincision complex and is essential for the 5′ incision by the ERCC1/XPF endonuclease. We have studied the dynamic role of XPG in its different cellular functions in living cells. We have created mammalian cell lines that lack functional endogenous XPG and stably express enhanced green fluorescent protein (eGFP)-tagged XPG. Life cell imaging shows that in undamaged cells XPG-eGFP is uniformly distributed throughout the cell nucleus, diffuses freely, and is not stably associated with other nuclear proteins. XPG is recruited to UV-damaged DNA with a half-life of 200 s and is bound for 4 min in NER complexes. Recruitment requires functional TFIIH, although some TFIIH mutants allow slow XPG recruitment. Remarkably, binding of XPG to damaged DNA does not require the DDB2 protein, which is thought to enhance damage recognition by NER factor XPC. Together, our data present a comprehensive view of the in vivo behavior of a protein that is involved in a complex chromatin-associated process.

Sign in / Sign up

Export Citation Format

Share Document