Microhomology-mediated and nonhomologous repair of a double-strand break in the chloroplast genome of Arabidopsis

Chloroplast DNA (cpDNA) is under great photooxidative stress, yet its evolution is very conservative compared with nuclear or mitochondrial genomes. It can be expected that DNA repair mechanisms play important roles in cpDNA survival and evolution, but they are poorly understood. To gain insight into how the most severe form of DNA damage, a double-strand break (DSB), is repaired, we have developed an inducible system in Arabidopsis that employs a psbA intron endonuclease from Chlamydomonas, I-CreII, that is targeted to the chloroplast using the rbcS1 transit peptide. In Chlamydomonas, an I-CreII-induced DSB in psbA was repaired, in the absence of the intron, by homologous recombination between repeated sequences (20–60 bp) abundant in that genome; Arabidopsis cpDNA is very repeat poor, however. Phenotypically strong and weak transgenic lines were examined and shown to correlate with I-CreII expression levels. Southern blot hybridizations indicated a substantial loss of DNA at the psbA locus, but not cpDNA as a whole, in the strongly expressing line. PCR analysis identified deletions nested around the I-CreII cleavage site indicative of DSB repair using microhomology (6–12 bp perfect repeats, or 10–16 bp with mismatches) and no homology. These results provide evidence of alternative DSB repair pathways in the Arabidopsis chloroplast that resemble the nuclear, microhomology-mediated and nonhomologous end joining pathways, in terms of the homology requirement. Moreover, when taken together with the results from Chlamydomonas, the data suggest an evolutionary relationship may exist between the repeat structure of the genome and the organelle''s ability to repair broken chromosomes.     

Improving the Transition from Residential to Outpatient Addiction Treatment: Gender Differences in Response to Supportive Telephone Calls

Substance use relapse rates are often high in the first months after discharge from inpatient substance abuse treatment, and patient adherence to aftercare plans is often low. Four residential addiction treatment centers participated in a feasibility study designed to estimate the efficacy of a post-discharge telephone intervention intended to encourage compliance with aftercare. A total of 282 participants (100 women, 182 men) with substance use disorders were included in this secondary analysis. The findings revealed that women were more likely than men to attend aftercare. This “gender effect” persisted after adjustment for a number of potential mediators.     

Hospice Characteristics and the Disenrollment of Patients with Cancer

Objective. To characterize the types of hospices with higher rates of patient disenrollment from the Medicare Hospice Benefit and the markets in which these hospices operate. Data Source. Secondary analyses of Surveillance, Epidemiology and End Results‐Medicare data. Analyses included patients who died of cancer from 1998 to 2002 and who used hospice (n=90,826). Study Design. We used generalized estimating equations to estimate the association of patient disenrollment with hospice size, years since Medicare certification, ownership, staff mix, competition, urban/rural status, region, and fiscal intermediary. Other covariates included patient demographic and clinical characteristics. Principal Findings. Patients were more likely to disenroll from hospice if they were served by newer hospices (OR=1.14; 95 percent CI 1.03, 1.26), by smaller hospices (OR=1.11; 95 percent CI 1.02, 1.20), or by hospices in more competitive markets (OR=1.17; 95 percent CI 1.03, 1.35). There was an independent effect of the hospice's fiscal intermediary on disenrollment, particularly disenrollment after 6 months with hospice (Wald χ²=21.2, p=.007). Conclusions. The reasons for higher disenrollment rates for newer hospices, for smaller hospices, and for hospices in highly competitive markets are likely complex; however, results suggest that there are organizational‐level barriers to keeping patients with cancer enrolled with hospice. Variation across fiscal intermediaries may indicate that regulatory oversight, particularly of long‐stay patients, influences hospice disenrollment.     

Intravenous Immunoglobulin Therapy in Autoimmune Mucocutaneous Blistering Diseases

Intravenous immunoglobulin (IVIg) is a biologic agent that is being increasingly used in the treatment of autoimmune and chronic inflammatory disorders. It is approved by the US FDA for the treatment of primary immunodeficiencies, immune thrombocytopenic purpura, Kawasaki disease, bone marrow transplantation in patients aged over 20 years, chronic B-cell lymphocytic leukemia, and pediatric AIDS. IVIg has been used off-label for several diseases, clinical symptoms and syndromes. Our aim was to determine if there is evidence to support the efficacy of IVIg therapy in autoimmune mucocutaneous blistering diseases (AMBDs). We searched the PubMed database for studies on pemphigus and pemphigoid using the following criteria: (i) English language; (ii) minimum of five patients; (iii) diagnosis based on histology and immunopathology; and (iv) statistical analysis of data for comparison of efficacy provided. We evaluated the data and present information on the number of participants in each study, pre-IV g therapy, indications for the use of IVIg, IVIg protocol (dose and interval) used, concomitant therapies, clinical outcome, follow-up period, and serologic studies. The quality of the evidence presented in this review is at Level A according to the UK National Health Service criteria. Twenty-three studies that were published between May 1999 and April 2010 were identified. One randomized controlled trial was found and all other studies were case series. Data on 260 patients treated with IVIg were analyzed: 191 patients with pemphigus and 69 patients with pemphigoid. Overall, 245 patients showed improvement with IVIg therapy. IVIg demonstrated a corticosteroid-sparing effect. In the studies presented, the incidence of serious adverse effects was not significant. The best available evidence in the literature indicates that IVIg is efficacious and has a good safety profile in the treatment of AMBDs.     

The oral implications of Hodgkin's disease

Hodgkin's disease is a cancer involving the lymphatics. While the yearly total of new cases is only approximately 7,500, the disease is very curable with modern radiotherapy and/or combination chemotherapy. This represents an increasing number of survivors who require dental treatment. Unfortunately, the treatment for Hodgkin's results in significant, permanent complications that persist for the duration of the patient's life. These complications can include xerostomia, radiation-induced caries, the risk of osteoradionecrosis in irradiated bone, and systemic complications such as a reduced immune response to microorganisms. These patients can and do undergo all types of dental treatment safely as long as the practitioner recognizes the risks involved and takes appropriate precautions.     

Enrolling older persons in cancer trials: the effect of sociodemographic, protocol, and recruitment center characteristics.

PURPOSE: To determine the effect of patient, protocol, geographic, and institutional factors on enrollment of older persons onto cancer trials. METHODS: We conducted a cross-sectional analysis of patients enrolled onto National Cancer Institute-sponsored lung, breast, colorectal, and prostate cancer trials during 1996 to 2002. We used a cross-classified logistic multilevel model to examine the associations between patient, hospital, county, and protocol characteristics, and the likelihood of participants being elderly (>or= 65 years old). RESULTS: The final study sample consisted of 36,167 patients enrolled onto 33 trials. After accounting for cancer type, only 6% of the variation in elderly enrollment onto cancer trials was at the protocol level. In contrast, more than 55% of the variation in elderly enrollment was attributable to patient level variation. In multivariate analysis, nonwhite patients were significantly less likely to be elderly than whites (odds ratio [OR] for blacks, 0.51; 95% CI, 0.44 to 0.58; and OR for Hispanics, 0.49; 95% CI, 0.40 to 0.59 v whites). Participants living less than 7 miles from their recruitment center were significantly more likely to be elderly (OR, 1.31; 95% CI, 1.24 to 1.38). Among the 910 recruitment centers, the median adjusted proportion of patients who were elderly was 24.9% (interquartile range, 24.0% to 26.9%). There were a significantly higher number of outlier centers (or= 29.3% elderly) than would be expected by a normal distribution (68 observed v six expected; P < .0001). CONCLUSION: Race and proximity to trial enrollment centers were significantly related to age of trial participants after adjusting for protocol factors. Additional work should explore why some recruitment centers were outliers regarding enrollment of older persons.