Fusion of nearby inverted repeats by a replication-based mechanism leads to formation of dicentric and acentric chromosomes that cause genome instability in budding yeast

Large-scale changes (gross chromosomal rearrangements [GCRs]) are common in genomes, and are often associated with pathological disorders. We report here that a specific pair of nearby inverted repeats in budding yeast fuse to form a dicentric chromosome intermediate, which then rearranges to form a translocation and other GCRs. We next show that fusion of nearby inverted repeats is general; we found that many nearby inverted repeats that are present in the yeast genome also fuse, as does a pair of synthetically constructed inverted repeats. Fusion occurs between inverted repeats that are separated by several kilobases of DNA and share >20 base pairs of homology. Finally, we show that fusion of inverted repeats, surprisingly, does not require genes involved in double-strand break (DSB) repair or genes involved in other repeat recombination events. We therefore propose that fusion may occur by a DSB-independent, DNA replication-based mechanism (which we term “faulty template switching”). Fusion of nearby inverted repeats to form dicentrics may be a major cause of instability in yeast and in other organisms.     

Cytotoxicity and mitochondrial dysfunction of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in isolated rat hepatocytes

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant that induces hepatic and extrahepatic oxidative stress and the mechanisms of TCDD-induced reactive oxygen species are not fully investigated. Moreover, the potential toxicity of TCDD in isolated rat hepatocytes is not fully explored. The aim of the current study was to explore the possible cytotoxic effect of TCDD on primary rat hepatocytes and to explore the impact of mitochondria in TCDD-induced toxicity. Hepatocytes were isolated from adult rat liver and incubated with 0, 5, 10 or 15 nM of TCDD for 24, 48 and 72 h. Cell viability, lactate dehydrogenase (LDH) leakage into media along with reactive oxygen species (ROS) generation and hydrogen peroxide (H₂O₂) production, mitochondrial membrane potential (Δψ_m), superoxide dismutase (SOD), catalse (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), total thiol contents, hepatic aryl hydrocarbon hydroxylase (AHH), and ethoxyresorufin O-deethylase (EROD) were performed in hepatocytes. In addition, superoxide anion generation, lipid peroxidation (LPO), mitochondrial protein carbonyl content and respiratory chain complexes II and IV were assayed in hepatocyte mitochondria. Cell viability was significantly decreased while LDH leakage into media was significantly increased in a dose and time related manner. ROS generation and H₂O₂ production along with EROD and AHH activities were significantly increased in hepatocytes in the same pattern. The antioxidant enzymes SOD, CAT, GPx and GR and the non-enzymatic protein thiols, in addition to Δψ_m were significantly decreased in hepatocytes in a concentration and time dependent pattern. On the other side, mitochondrial superoxide anion along with LPO and mitochondrial protein carbonyl content were significantly increased while the respiratory chain complexes II and IV activities were significantly decreased in hepatocyte mitochondria. This effect may lead to disruption in the functional integrity of hepatocytes and hepatocyte mitochondria. In conclusion, our data clearly show that TCDD induces hepatocyte toxicity and mitochondrial dysfunction by a mechanism involving generation of ROS. Mitochondria might be the primary source of (or at least contribute to) the oxidative stress response and resulting toxicological outcomes elicited by TCDD.     

Necrotizing panniculitis: a skin condition associated with acinar cell carcinoma of the pancreas

Pancreatic panniculitis (PP) is a rare cutaneous eruption that is associated with severe pancreatic disease. A patient presented with a fever, joint pains, and an erythematous rash with draining pustules that had spread from his legs to his arms over 4 months. Thorough investigation revealed stage IV acinar cell carcinoma of the pancreas. The rash was a result of necrotizing PP. The variable cutaneous manifestations of internal malignancies may challenge primary care physicians and dermatologists when patients present without findings associated with malignancy. Panniculitis should be kept in mind in the differential diagnosis of inflamed appearing nodules and pustules with an erythematous base, particularly when they are progressive and unrelenting.     

Factors associated with adverse neurodevelopmental outcomes in infants with congenital heart disease

OBJECTIVE: To review reported neurodevelopmental outcome data for patients with congenital heart disease, identify risk factors for adverse neurodevelopmental sequelae and summarize potential neuromonitoring strategies that have been described. METHODS: A Medline search was performed utilizing combinations of the keywords congenital heart, cardiac, neurologic, neurodevelopment, neuromonitoring, quality of life, and outcome. All prospective and longitudinal follow-up studies of patients with congenital heart disease were included. Additionally, studies that examined neuroimaging, neuromonitoring, and clinical factors in relation to outcome were examined. Case reports and editorials were excluded. Additional references were retrieved from selected articles if the abstract described an evaluation of neurodevelopmental outcomes and/or predictors of outcome in patients with congenital heart disease. RESULTS: Overall, patients with CHD have increased rates of neurodevelopmental impairments, although intelligence appears to be in the normal range. Preoperative risk stratification, intraoperative techniques, postoperative care, and neuromonitoring strategies may all contribute to ultimate long-term neurodevelopmental outcomes in patients with CHD postsurgical repair. CONCLUSIONS: As advances in the medical and surgical management improves survival in patients with CHD, increasing knowledge about neurodevelopmental outcomes and the factors that affect them will provide for strategies to optimize long-term outcome in this high-risk population.     

Two single nucleotide polymorphisms identify the highest-risk diabetes HLA genotype: potential for rapid screening

OBJECTIVE—People with the HLA genotype DRB1*0301-DQA1*0501-DQB1*0201/DRB1*04-DQA1*0301-DQB1*0302 (DR3/4-DQ8) are at the highest risk of developing type 1 diabetes. We sought to find an inexpensive, rapid test to identify DR3/4-DQ8 subjects using two single nucleotide polymorphisms (SNPs).RESEARCH DESIGN AND METHODS—SNPs rs2040410 and rs7454108 were associated with DR3-DQB1*0201 and DR4-DQB1*0302. We correlated these SNPs with HLA genotypes and with publicly available data on 5,019 subjects from the Type 1 Diabetes Genetic Consortium (T1DGC). Additionally, we analyzed these SNPs in samples from 143 HLA-typed children who participated in the Diabetes Autoimmunity Study of the Young (DAISY) using Taqman probes (rs7454108) and restriction digest analysis (rs2040410).RESULTS—With a simple combinatorial rule, the SNPs of interest identified the presence or absence of the DR3/4-DQ8 genotype. A wide variety of genotypes were tested for both SNPs. In T1DGC samples, the two SNPs were 98.5% (1,173 of 1,191) sensitive and 99.7% (3,815 of 3,828) specific for DR3/4-DQ8. In the DAISY population, the test was 100% (69 of 69) sensitive and 100% (74 of 74) specific. Overall, the sensitivity and specificity for the test were 98.57 and 99.67%, respectively.CONCLUSIONS—A two-SNP screening test can identify the highest risk heterozygous genotype for type 1 diabetes in a time- and cost-effective manner.We have the ability to identify subjects with a greater than 50% risk of developing anti-islet autoimmunity and type 1 diabetes on the basis of family history and HLA genotype (1,2). Siblings with the highest type 1 diabetes risk HLA genotype DRB1*0301-DQA1*0501-DQB1*0201/DRB1*04-DQA1*0301-DQB1*0302 (DR3/4-DQ8) who are identical by descent for the major histocompatibility complex region with a type 1 diabetic sibling have an 85% risk of developing diabetes-related autoimmunity by age 15 years and a 55% risk of developing type 1 diabetes by age 12 years (1). Children with multiple first-degree relatives with type 1 diabetes and high–or moderate–diabetes risk HLA genotypes are reported to have a 50% risk for the development of multiple diabetes-related autoantibodies and type 1 diabetes (2).Prevention trials, including the Trial to Reduce Type 1 Diabetes in the Genetically at Risk (TRIGR) (3), the Nutritional Intervention to Prevent Diabetes (NIP-Diabetes) trial (4), and the Primary Oral and Intranasal Trial (Pre-POINT) are currently underway in genetically at-risk children. Many of these trials include first-degree relatives of people with diabetes as well as individuals with high-risk HLA genotypes, including DR3/4-DQ8. The identification of subjects for these trials requires large-scale HLA screening, with many children tested who do not have the highest type 1 diabetes risk. Current typing techniques for DR3/4-DQ8 often utilize coamplification of the DQA1 and DQB1 genes followed by multiple probe hybridization or direct sequencing. This technique uses sequence-specific oligonucleotides in a linear assay for hybridization with amplified product from DNA samples (5). Alleles are called with a customized typing program. Sequence-based typing techniques use PCR to amplify DRB1 genes that are sequenced, with HLA type determined using special software (6). High-throughput screening systems that employ asymmetric PCR and hybridization of allele-specific probes as a first screening step to identify samples with specified HLA genotypes have been developed. Samples identified via these programs can be identified for further HLA genotyping (7). This method is cost and time consuming, as it may cost up to $31.44 to genotype 1 sample and takes up to 9 h to perform and analyze a set of 50 samples.Several studies have examined the possibility of predicting HLA alleles from existing single nucleotide polymorphism (SNP) data (8–10); however, only one article has provided data on predicting specific HLA alleles from individual SNPs. de Bakker et al. (8) reported an association between HLA types and SNPs. SNP rs2040410 A allele was associated with DRB1*0301, and rs7454108 C allele with DQB1*0302. We have developed and tested the ability of these two SNPs to identify individuals with the DR3/4-DQ8 genotype in subjects within the Type 1 Diabetes Genetics Consortium (T1DGC) and the Diabetes Autoimmunity Study in the Young (DAISY). This novel method adds to existing knowledge by utilizing SNP technology to quickly identify individuals with the DR3/4-DQ8 genotype and may be beneficial to prevention trials because it provides high-throughput screening in a time- and cost-effective manner.     

Ciclopirox gel for seborrheic dermatitis of the scalp

Background Seborrheic dermatitis is a common inflammatory skin disorder that usually occurs in patients with pre‐existing seborrhea. The etiology of seborrheic dermatitis is uncertain. Typically, sites dense with sebaceous glands support growth of the lipophilic yeast Malassezia furfur. Ciclopirox (Loprox®) gel is a hydroxypyridone, broad‐spectrum antifungal agent proven effective against the yeast M. furfur. Objective A multicenter, randomized, double‐blind, vehicle controlled study of 178 subjects evaluated the efficacy of ciclopirox gel in treating seborrheic dermatitis of the scalp. Methods One hundred and seventy‐eight subjects were randomized to apply either ciclopirox gel 0.77% twice daily, or vehicle twice daily for 28 days. Subjects’ signs and symptoms of severity (erythema, scaling, pruritus and burning) were rated on a scale of 0–3 (none to severe); for inclusion, a minimum score of 4, for the sum of the individual ratings was required. Efficacy evaluations were performed at baseline, days 4, 8, 15, 22, 29, and at end‐point (final visit, up to day 33). The primary efficacy variable was clinical response assessed by a global improvement, based on a scale of 0–5 (100% clearance to flare of treatment area). Changes in signs/symptoms severity scores within the target lesion were also evaluated. Results Global evaluation scores demonstrated that significantly more ciclopirox‐treated subjects achieved over 75% improvement compared with vehicle at days 22, 29, and endpoint (P < 0.01). Change‐from‐baseline mean score for total signs and symptoms was significantly greater in ciclopirox subjects compared with vehicle subjects at the same time points as above (P < 0.001), as well as day 15 (P < 0.01). Twenty‐nine percent of subjects rated ciclopirox as having excellent cosmetic acceptability. There were only mild adverse events, with the most common being burning sensation in 13% of ciclopirox subjects and 9% of vehicle subjects. Conclusion Ciclopirox gel is effective and safe in the treatment of seborrheic dermatitis of the scalp.     

Live/Real Time Three‐Dimensional Transthoracic Echocardiographic Assessment of Pericardial Disease

We studied 19 patients with pericardial disease using two‐dimensional and three‐dimensional transthorathic echocardiography (2DTTE and 3DTTE, respectively) in order to determine whether 3DTTE provides incremental value on top of 2DTTE in the evaluation of these patients. With 3DTTE a more comprehensive assessment of pericardial effusion can be made and both the parietal and visceral layers of the pericardium can be visualized en face and examined for pathologies and fibrin deposits. In our series of patients, 3DTTE was superior to 2DTTE in uncovering mass lesions involving the pericardium such as tuberculous granulomas and metastatic disease. Furthermore, it provided a better assessment of the nature of pericardial lesions, such as pericardial and mediastinal hematomas, pericardial cysts, and metastatic disease to the pericardium by sequential cropping of the 3D data sets and visualizing the interior of the lesions in a manner not possible with 2DTTE. It was also valuable in determining the extent of pericardial calcification in pericardial constriction and in measuring the size of pericardial masses. These preliminary results suggest the superiority of 3DTTE over 2DTTE in the evaluation of pericardial diseases and that it provides incremental knowledge to the echocardiographer. (ECHOCARDIOGRAPHY, Volume 26, November 2009)     

Electrosurgery-induced endotracheal tube ignition during tracheotomy

Electrosurgery was the most common source of ignition for operating room fires prior to the advent of lasers. When combined with volatile anesthetic mixtures, electrosurgery has caused ignition of plastic, rubber, paper, enteric gases, and combustible preparation solutions. We report on an intubated patient whose polyvinyl chloride endotracheal tube ignited during a tracheotomy performed with an electrosurgical unit. The oxygen-rich environment, the polyvinyl chloride tube, and the heat generated by the electrosurgical unit combined to produce a fire. Since otolaryngologists are called upon often to perform tracheotomies on intubated patients, it is imperative that they understand the factors involved in the development of such a fire. This case is presented with an explanation of why this type of fire occurs. A brief review of the literature is included. Different kinds of electrosurgical units, precautions as to their use, and the management of electrosurgery-induced endotracheal tube fires are also discussed.     

Comparative results of the immunogenicity of Edmonston-Zagreb and Schwartz measles vaccines administered to 60 Egyptian infants.

The present study was conducted on sixty 9-11 month infants attending a primary care clinic in a rural Giza governorate area. Patients were divided into two groups: the first group comprised 42 infants who were vaccinated with the Edmonston Zagreb measles vaccine strain, whereas the second group comprised 18 infants who were vaccinated with the Schwartz measles vaccine strain. Estimation of measles antibody titer by neutralization testing was determined by the microtiter technique prior to and 4 weeks post vaccination. The overall serconversion rate was 85%. Three infants failed vaccination. The Edmonston-Zagreb strain was superior to the Schwartz strain in inducing immunity to non immune infants. The nutritional status of the study group was abnormal in almost 1/2 (29/60) infants and borderline in 1/3 (20/60).