Replacing LNT: The Integrated LNT-Hormesis Model.

Many scientists and regulators utilize the linear no-threshold (LNT) relationship to estimate the likelihood of carcinogenesis. The LNT model is incorrect and was adopted based upon false pretenses. The use of the model has been corrupted by many to claim that even the smallest ionizing radiation dose may initiate carcinogenesis.

A MLC-based inversely optimized 3D spatially fractionated grid radiotherapy technique.

This study presents a MLC-based, 3D grid-therapy technique with characteristics of both 3D-conformal-radiotherapy and grid-therapy. It generates a brachytherapy-like dose distribution, with D50% of 20, 9.8, 5.

Can radiation risks to patients be reduced without reducing radiation exposure? The status of chemical radioprotectants.

Objective: Medical radiation exposure has increased sixfold since 1980 and is the largest controllable source of exposure. Many efforts have been devoted to reducing dose or eliminating unnecessary examinations but with limited success. The concern regarding nuclear terrorism has focused a large amount of attention on radioprotective drugs.

Helper-independent piggyBac plasmids for gene delivery approaches: strategies for avoiding potential genotoxic effects.

Efficient integration of functional genes is an essential prerequisite for successful gene delivery such as cell transfection, animal transgenesis, and gene therapy. Gene delivery strategies based on viral vectors are currently the most efficient. However, limited cargo capacity, host immune response, and the risk of insertional mutagenesis are limiting factors and of concern.

piggyBac transposon/transposase system to generate CD19-specific T cells for the treatment of B-lineage malignancies.

Nonviral integrating vectors can be used for expression of therapeutic genes. piggyBac (PB), a transposon/transposase system, has been used to efficiently generate induced pluripotent stems cells from somatic cells, without genetic alteration. In this paper, we apply PB transposition to express a chimeric antigen receptor (CAR) in primary human T cells.

Lithium chloride protects retinal neurocytes from nutrient deprivation by promoting DNA non-homologous end-joining.

Lithium chloride is a therapeutic agent for treatment of bipolar affective disorders. Increasing numbers of studies have indicated that lithium has neuroprotective effects. However, the molecular mechanisms underlying the actions of lithium have not been fully elucidated.

Medical countermeasures against nuclear threats: radionuclide decorporation agents.

Exposure to radionuclides disseminated by a radiological dispersion device or deposited as fallout after a nuclear power plant accident or detonation of an improvised nuclear device could result in internal contamination of a significant number of individuals. Internalized radionuclides may cause both acute and chronic radiation injury and increase an individual's risk of developing cancer. This damage and risk can be mitigated by the use of decorporation agents that reduce internal contamination.

Use of intracytoplasmic sperm injection (ICSI) to generate transgenic animals.

Even though intracytoplasmic sperm injection (ICSI) has been widely used for the production of offspring in human infertility clinics and in reproductive research laboratories using mice, many researchers engaged in animal transgenesis still consider it somewhat cumbersome. The greatest advantage of ICSI-mediated transgenesis is that it allows introduction of very large DNA transgenes (e.g.

Medical countermeasures for radiation combined injury: radiation with burn, blast, trauma and/or sepsis. report of an NIAID Workshop, March 26-27, 2007.

Non-clinical human radiation exposure events such as the Hiroshima and Nagasaki bombings or the Chernobyl accident are often coupled with other forms of injury, such as wounds, burns, blunt trauma, and infection. Radiation combined injury would also be expected after a radiological or nuclear attack. Few animal models of radiation combined injury exist, and mechanisms underlying the high mortality associated with complex radiation injuries are poorly understood.

Steps toward targeted insertional mutagenesis with class II transposable elements.

Insertional mutagenesis can be achieved by a variety of approaches, including both random and targeted methods. In contrast to chemical mutagenesis, insertional mutagens provide a molecular tag, thereby allowing rapid identification of the mutated genomic region. Integration into defined genomic locations has great utility for both gene insertion and mutagenesis.

The role of mTOR inhibition in augmenting radiation induced autophagy.

Radiation affects both tumor and normal tissues, limiting the total delivered radiation dose. Therefore, novel ways to exploit molecular targets and improve the therapeutic ratio are continually being investigated. Autophagy plays an important role in cancer cell death decisions, particularly in solid tumors.

CXCR4 down-regulation by small interfering RNA inhibits invasion and tubule formation of human retinal microvascular endothelial cells.

The progressive alterations to the retinal microvasculature in diabetic retinopathy are known to cause vision loss. Chemokines are characterized by their ability to induce cell invasion, adhesion and migration. In this study, we used double siRNA transfection to transiently and selectively decrease the level of the endogenous CXCR4 in human retinal microvascular endothelial cells (HRMECs).

Active integration: new strategies for transgenesis.

This paper presents novel methods for producing transgenic animals, with a further emphasis on how these techniques may someday be applied in gene therapy. There are several passive methods for transgenesis, such as pronuclear microinjection (PNI) and Intracytoplasmic Sperm Injection-Mediated Transgenesis (ICSI-Tr), which rely on the repair mechanisms of the host for transgene (tg) insertion. ICSI-Tr has been shown to be an effective means of creating transgenic animals with a transfection efficiency of approximately 45% of animals born.

piggyBac is a flexible and highly active transposon as compared to sleeping beauty, Tol2, and Mos1 in mammalian cells.

A nonviral vector for highly efficient site-specific integration would be desirable for many applications in transgenesis, including gene therapy. In this study we directly compared the genomic integration efficiencies of piggyBac, hyperactive Sleeping Beauty (SB11), Tol2, and Mos1 in four mammalian cell lines. piggyBac demonstrated significantly higher transposition activity in all cell lines whereas Mos1 had no activity.

Functional zinc finger/sleeping beauty transposase chimeras exhibit attenuated overproduction inhibition.

The sleeping beauty (SB) transposon system has potential utility in gene transfer applications but lacks specificity for genomic integration and exhibits overproduction inhibition which limits in vivo activity. Targeting transposition may be possible by coupling a specific DNA binding domain to the SB transposase, but it is not known if this strategy will preserve or disrupt activity of the system. We engineered and tested chimeric SB transposases with two different human zinc finger DNA binding domain elements, Sp1 and zinc finger 202 (ZNF202).

Site-directed genome modification: derivatives of DNA-modifying enzymes as targeting tools.

The modification of mammalian genomes is an important goal in gene therapy and animal transgenesis. To generate stable genetic and biochemical changes, the therapeutic genes or transgenes need to be incorporated into the host genome. Ideally, the integration of the foreign gene should occur at sites that ensure their continual expression in the absence of any unwanted side effects on cellular metabolism.

Site-directed genome modification: nucleic acid and protein modules for targeted integration and gene correction.

A variety of technological advances in recent years have made permanent genetic manipulation of an organism a technical possibility. As the details of natural biological processes for genome modification are elucidated, the enzymes catalyzing these events (transposases, recombinases, integrases and DNA repair enzymes) are being harnessed or modified for the purpose of intentional gene modification. Targeted integration and gene repair can be mediated by the DNA-targeting specificity inherent to a particular enzyme, or rely on user-designed specificities.

The controversial abscopal effect.

The abscopal effect is potentially important for tumor control and is mediated through cytokines and/or the immune system, mainly cell-mediated immunity. It results from loss of growth stimulatory and/or immunosuppressive factors from the tumor. Until recently, the abscopal effect referred to the distant effects seen after local radiation therapy.

Effect of sequencing of androgen deprivation and radiotherapy on prostate cancer growth.

Purpose: Androgen deprivation (AD) is frequently combined with radiotherapy (RT); however, the optimal sequence in vivo is currently unknown. Previous published work from our laboratory demonstrated that AD with RT was consistent with at least an additive, and possibly supra-additive, effect with the combined approach. We, therefore, performed additional experiments to elucidate the optimal sequence.

Immunotherapy and prostate cancer.

Prostate cancer is the second leading cause of cancer death in the US, largely because of the limitations of our current therapeutic options, especially once the cancer has metastasized. Investigators have long sought new therapeutic modalities such as angiogenesis inhibitors, vaccines, and gene therapy, among others. It appears that a combination approach will be required to cure the majority of malignancies.