Persistence of Gamma-H2AX Foci in Irradiated Bronchial Cells Correlates with Susceptibility to Radiation Associated Lung Cancer in Mice

The risk of developing radiation-induced lung cancer differs between different strains of mice, but the underlying cause of the strain differences is unknown. Strains of mice also differ in their ability to efficiently repair DNA double strand breaks resulting from radiation exposure. We phenotyped mouse strains from the CcS/Dem recombinant congenic strain set for their efficacy in repairing DNA double strand breaks during protracted radiation exposures. We monitored persistent gamma-H2AX radiation induced foci (RIF) 24 hours after exposure to chronic gamma-rays as a surrogate marker for repair deficiency in bronchial epithelial cells for 17 of the CcS/Dem strains and the BALB/cHeN founder strain. We observed a very strong correlation R2 = 79.18%, P < 0.001) between the level of persistent RIF and radiogenic lung cancer percent incidence measured in the same strains. Interestingly, spontaneous levels of foci in non-irradiated strains also showed good correlation with lung cancer incidence (R2=32.74%, P =0.013). These results suggest that genetic differences in DNA repair capacity largely account for differing susceptibilities to radiation-induced lung cancer among CcS/Dem mouse strains and that high levels of spontaneous DNA damage is also a relatively good marker of cancer predisposition. In a smaller pilot study, we found that the repair capacity measured in peripheral blood leucocytes also correlated well with radiogenic lung cancer susceptibility, raising the possibility that such phenotyping assay could be used to detect radiogenic lung cancer susceptibility in humans

Two model systems for studying the effects of acute radiation exposure on gene deletions and amplifications

2014 Fall.Includes bibliographical references.Ionizing radiation (IR) poses a severe threat to genome integrity, and is an important source of environmental damage, arising from naturally occurring sources (e.g. radon and cosmic radiation) and medical imaging and therapy. Radiation exposure can lead to somatic changes in chromosomal structure such as copy number alterations (CNAs) resulting in gain or loss in copies of sections of DNA. To study copy number alterations in the human genome resulting from gamma radiation, early passage cultures of normal human fibroblasts were exposed to a single acute 4 Gy dose of radiation. Irradiated cells were kept for 48 h to allow repair of initial DNA damage. Single cell cloning was done by serial dilution in 96 well plates. Standard PCR was performed using seven sequence tagged site (STS) markers (SY 83, SY86, SY88, SY1190, SY1191, SY1201, and SY1206) of the azoospermia (AZF) region in the Y chromosome to test for microdeletions, in irradiated and non-irradiated cells. The comprehensive analysis of the molecular mechanism of copy number changes, requires a more elaborate experimental system in a model organism. Hence, we also investigated copy number alterations in diploid budding yeast cells after exposing them to two acute gamma radiation doses and detecting CNAs via a unique selection system, that involves events at two chromosomes. The copy number selective system used in our yeast samples allowed us to select for copy number alterations (duplications and deletions) in all samples after exposure to radiation, which lead to nonreciprocal translocation events formed by nonallelic homologous recombination (NAHR) mechanism. These results lead us to conclude that acute exposures to gamma radiation, induced deletions and amplifications as shown in both models. The experiments described in the thesis provide a platform for future work aimed at investigating the role low dose ionizing radiation on genome stability

A Systematic Review of the Role of Dysfunctional Wound Healing in the Pathogenesis and Treatment of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disorder showcasing an interaction between genetic predisposition and environmental risks. This usually involves the coaction of a mixture of cell types associated with abnormal wound healing, leading to structural distortion and loss of gas exchange function. IPF bears fatal prognosis due to respiratory failure, revealing a median survival of approximately 2 to 3 years. This review showcases the ongoing progress in understanding the complex pathophysiology of IPF and it highlights the latest potential clinical treatments. In IPF, various components of the immune system, particularly clotting cascade and shortened telomeres, are highly involved in disease pathobiology and progression. This review also illustrates two US Food and Drug Administration (FDA)-approved drugs, nintedanib (OFEV, Boehringer Ingelheim, Ingelheim am Rhein, Germany) and pirfenidone (Esbriet, Roche, Basel, Switzerland), that slow IPF progression, but unfortunately neither drug can reverse the course of the disease. Although the mechanisms underlying IPF remain poorly understood, this review unveils the past and current advances that encourage the detection of new IPF pathogenic pathways and the development of effective treatment methods for the near future

CXL shows no significant impact on protein expression of TIMPs in KC.

<p>(A) TIMP1, (B) TIMP2, in HCF.C and HKC.C: pre-CXL, and HCF.X and HKC.X: post-CXL. n = 4. Statistical significance was determined by one way ANOVA, with p ≤ 0.05 considered statistically significant. Error bars represent standard error of the mean **p<0.01.</p

Collagen cross-linking impact on keratoconus extracellular matrix - Fig 3

<p><b>CXL alters protein expression of MMPs</b>: (A) MMP1, (B) MMP2, (C) MMP3, and (D) MMP9, in HCF.C and HKC.C: pre-CXL, and HCF.X and HKC.X: post-CXL. n = 4. Statistical significance was determined by one way ANOVA, with p ≤ 0.05 considered statistically significant. Error bars represent standard error of the mean *p<0.05, **p<0.01.</p

Collagen cross-linking impact on keratoconus extracellular matrix - Fig 2

<p><b>CXL alters protein expression of PGs</b>: (A) Keratocan, (B) Lumican, (C) Mimecan, and (D) Decorin, in HCF.C and HKC.C: pre-CXL, and HCF.X and HKC.X: post-CXL. n = 4. Statistical significance was determined by one way ANOVA, with p ≤ 0.05 considered statistically significant. Error bars represent standard error of the mean *p<0.05, **p<0.01, ***p<0.001.</p

TEM image showing corneal matrix status.

<p>HCF.C and HKC.C: pre-CXL, and HCF.X and HKC.X: post-CXL, when cultured in our 3D model. Green arrows: proteoglycans; Blue star: collagen fibrils organization; Red line: collagen banding.</p

The Burr Spring 2012 Issue 2

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