A Case of Congenital Pulmonary Vein Stenosis with Secondary Post-Capillary Pulmonary Hypertension and Left Sided Congestive Heart Failure in a Cat.

A five-month-old, 3.8 kg intact male Maine coon cat presented for dyspnea characterized by increased respiratory effort in addition to open-mouth breathing. Thoracic radiographs showed pectus excavatum, enlarged cardiac silhouette, and generalized interstitial patterns.

Reduction of hazardous chemicals in Swedish preschool dust through article substitution actions.

Consumer goods and building materials present in the preschool environment can be important sources of hazardous chemicals, such as plasticizers, bisphenols, organophosphorus and brominated flame retardants, poly- and perfluoroalkyl substances, which may pose a health risk to children. Even though exposure occurs via many different pathways, such as food intake, inhalation, dermal exposure, mouthing of toys etc., dust has been identified as a valuable indicator for indoor exposure.

Homologous recombination mediates cellular resistance and fraction size sensitivity to radiation therapy.

Purpose: Cellular sensitivity to radiotherapy total dose and fraction size is strongly influenced by DNA double strand break (DSB) repair. Here, we investigate response to radiotherapy fraction size using CHO cell lines deficient in specific DNA repair pathways in response to radiation induced DNA double strand breaks (DSB).

Experimental Design: We irradiated CHO cell lines, AA8 (WT), irs1SF (XRCC3-), V3-3 (DNA-PKcs-) and EM9 (XRCC1-) with 16 Gy in 1 Gy daily fractions over 3 weeks or 16 Gy in 4 Gy daily fractions over 4 days, and studied clonogenic survival, DNA DSB repair kinetics (RAD51 and 53BP1 foci staining) and cell cycle profiles (flow cytometry).

CHK1 activity is required for continuous replication fork elongation but not stabilization of post-replicative gaps after UV irradiation.

Ultraviolet (UV)-induced DNA damage causes an efficient block of elongating replication forks. The checkpoint kinase, CHK1 has been shown to stabilize replication forks following hydroxyurea treatment. Therefore, we wanted to test if the increased UV sensitivity caused by the unspecific kinase inhibitor caffeine--inhibiting ATM and ATR amongst other kinases--is explained by inability to activate the CHK1 kinase to stabilize replicative structures.

Homologous recombination repairs secondary replication induced DNA double-strand breaks after ionizing radiation.

Ionizing radiation (IR) produces direct two-ended DNA double-strand breaks (DSBs) primarily repaired by non-homologous end joining (NHEJ). It is, however, well established that homologous recombination (HR) is induced and required for repair of a subset of DSBs formed following IR. Here, we find that HR induced by IR is drastically reduced when post-DNA damage replication is inhibited in mammalian cells.

The PCNA pseudogenes in the human genome.

Background: The proliferating cell nuclear antigen (PCNA) is a key protein in the eukaryotic DNA replication and cell proliferation. Following the cloning and characterisation of the human PCNA gene, the question of the existence of pseudogenes in the human genome was raised.

Findings: In this short communication we summarise the existing information about the PCNA pseudogenes and critically assess their status.

CK2 phosphorylation of XRCC1 facilitates dissociation from DNA and single-strand break formation during base excision repair.

CK2 phosphorylates the scaffold protein XRCC1, which is required for efficient DNA single-strand break (SSB) repair. Here, we express an XRCC1 protein (XRCC1(ckm)) that cannot be phosphorylated by CK2 in XRCC1 mutated EM9 cells and show that the role of this post-translational modification gives distinct phenotypes in SSB repair and base excision repair (BER). Interestingly, we find that fewer SSBs are formed during BER after treatment with the alkylating agent dimethyl sulfate (DMS) in EM9 cells expressing XRCC1(ckm) (CKM cells) or following inhibition with the CK2 inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT).

DNA repair and replication influence the number of mutations per adduct of polycyclic aromatic hydrocarbons in mammalian cells.

Polycyclic aromatic hydrocarbons (PAH) are an important class of environmental contaminants many of which require metabolic activation to DNA-reactive bay or fjord region diolepoxides (DE) in order to exert their mutagenic and carcinogenic effects. In this study, the mutagenicity of the bay region diolepoxides (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) and (±)-anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrodibenzo[a,h]anthracene (DBADE) and the fjord region diolepoxides (±)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]-pyrene (DBPDE) and (±)-anti-3,4-dihydroxy-1,2-epoxy-1,2,3,4-tetrahydrobenzo[c]-phenanthrene (BPhDE) was compared in nucleotide excision repair (NER) proficient and deficient hamster cell lines. The (32)P-postlabelling assay was applied to analyze DNA adduct levels and the Hprt gene mutation assay for monitoring mutations.

Structural requirements for mutation formation from polycyclic aromatic hydrocarbon dihydrodiol epoxides in their interaction with food chemopreventive compounds.

Chinese hamster V79 cells were used to investigate the protective effect of four known antimutagens present in food, chlorophyllin (CHL), ellagic acid (EA), epigallocathechingallate (EGCG) and benzylisothiocyanate (BITC), against potent mutagenic polycyclic aromatic hydrocarbon diol epoxides (PAH-DE) derived from benzo[a]pyrene (BP), dibenzo[a,h]anthracene (DBA), dibenzo[a,l]pyrene (DBP), and benzo[c]phenanthrene (BPh) known to be deposited on crops from polluted ambient air or formed during food processing. As fjord-region PAH-DE are more toxic and mutagenic than bay-region PAH-DE, we adjusted the concentrations of PAH-DE to induce approximately the same levels of adducts. The studies were performed using an assay indicating toxicity in terms of reduced cell proliferation together with the V79 Hprt assay for monitoring mutant frequencies.

Both replication bypass fidelity and repair efficiency influence the yield of mutations per target dose in intact mammalian cells induced by benzo[a]pyrene-diol-epoxide and dibenzo[a,l]pyrene-diol-epoxide.

Mutations induced by polycyclic aromatic hydrocarbons (PAH) are expected to be produced when error-prone DNA replication occurs across unrepaired DNA lesions formed by reactive PAH metabolites such as diol epoxides. The mutagenicity of the two PAH-diol epoxides (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) and (+/-)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]pyrene (DBPDE) was compared in nucleotide excision repair (NER) proficient and deficient hamster cell lines. We applied the (32)P-postlabelling assay to analyze adduct levels and the hprt gene mutation assay for monitoring mutations.

Caffeine delays replication fork progression and enhances UV-induced homologous recombination in Chinese hamster cell lines.

The ability to bypass DNA lesions encountered during replication is important in order to maintain cell viability and avoid genomic instability. Exposure of mammalian cells to UV-irradiation induces the formation of DNA lesions that stall replication forks. In order to restore replication, different bypass mechanisms are operating, previously named post-replication repair.

A method to monitor replication fork progression in mammalian cells: nucleotide excision repair enhances and homologous recombination delays elongation along damaged DNA.

The capacity to rescue stalled replication forks (RFs) is important for the maintenance of cell viability and genome integrity. Here, we have developed a novel method for monitoring RF progression and the influence of DNA lesions on this process. The method is based on the principle that each RF is expected to be associated with a pair of single-stranded ends, which can be analyzed by employing strand separation in alkali.