Syndicate content
Recent documents in eScholarship@UMMS
Updated: 2 hours 56 min ago

Phosphorylation of the Peptidoglycan Synthase PonA1 Governs the Rate of Polar Elongation in Mycobacteria

Thu, 08/13/2015 - 9:42am

Cell growth and division are required for the progression of bacterial infections. Most rod-shaped bacteria grow by inserting new cell wall along their mid-section. However, mycobacteria, including the human pathogen Mycobacterium tuberculosis, produce new cell wall material at their poles. How mycobacteria control this different mode of growth is incompletely understood. Here we find that PonA1, a penicillin binding protein (PBP) capable of transglycosylation and transpeptidation of cell wall peptidoglycan (PG), is a major governor of polar growth in mycobacteria. PonA1 is required for growth of Mycobacterium smegmatis and is critical for M. tuberculosis during infection. In both cases, PonA1's catalytic activities are both required for normal cell length, though loss of transglycosylase activity has a more pronounced effect than transpeptidation. Mutations that alter the amount or the activity of PonA1 result in abnormal formation of cell poles and changes in cell length. Moreover, altered PonA1 activity results in dramatic differences in antibiotic susceptibility, suggesting that a balance between the two enzymatic activities of PonA1 is critical for survival. We also find that phosphorylation of a cytoplasmic region of PonA1 is required for normal activity. Mutations in a critical phosphorylated residue affect transglycosylase activity and result in abnormal rates of cell elongation. Together, our data indicate that PonA1 is a central determinant of polar growth in mycobacteria, and its governance of cell elongation is required for robust cell fitness during both host-induced and antibiotic stress.

Connecting Circadian Genes to Neurodegenerative Pathways in Fruit Flies

Thu, 08/13/2015 - 9:42am

Article introduction: Life expectancy has dramatically increased in recent human history. As a result, neurodegenerative diseases have become a primary health issue. Circadian clocks are found in all mammalian tissues, including neurons and glia, and are, thus, likely to have an impact on the onset and progression of neurodegenerative diseases. However, the link between circadian clocks and neurodegeneration is poorly understood. ...

Mesoscopic patterns of neural activity support songbird cortical sequences

Thu, 08/13/2015 - 9:42am

Time-locked sequences of neural activity can be found throughout the vertebrate forebrain in various species and behavioral contexts. From "time cells" in the hippocampus of rodents to cortical activity controlling movement, temporal sequence generation is integral to many forms of learned behavior. However, the mechanisms underlying sequence generation are not well known. Here, we describe a spatial and temporal organization of the songbird premotor cortical microcircuit that supports sparse sequences of neural activity. Multi-channel electrophysiology and calcium imaging reveal that neural activity in premotor cortex is correlated with a length scale of 100 microm. Within this length scale, basal-ganglia-projecting excitatory neurons, on average, fire at a specific phase of a local 30 Hz network rhythm. These results show that premotor cortical activity is inhomogeneous in time and space, and that a mesoscopic dynamical pattern underlies the generation of the neural sequences controlling song.

Data from: PTC124 Targets Genetic Disorders Caused by Nonsense Mutations

Tue, 08/11/2015 - 11:35am

Manuscript abstract: Nonsense mutations promote premature translational termination and cause anywhere from 5-70% of the individual cases of most inherited diseases. Studies on nonsense-mediated cystic fibrosis have indicated that boosting specific protein synthesis from less than 1% to as little as 5% of normal levels may greatly reduce the severity or eliminate the principal manifestations of disease. To address the need for a drug capable of suppressing premature termination, we identified PTC124-a new chemical entity that selectively induces ribosomal readthrough of premature but not normal termination codons. PTC124 activity, optimized using nonsense-containing reporters, promoted dystrophin production in primary muscle cells from humans and mdx mice expressing dystrophin nonsense alleles, and rescued striated muscle function in mdx mice within 2-8 weeks of drug exposure. PTC124 was well tolerated in animals at plasma exposures substantially in excess of those required for nonsense suppression. The selectivity of PTC124 for premature termination codons, its well characterized activity profile, oral bioavailability and pharmacological properties indicate that this drug may have broad clinical potential for the treatment of a large group of genetic disorders with limited or no therapeutic options.

Influence of family, friend and coworker social support and social undermining on weight gain prevention among adults

Mon, 08/10/2015 - 8:35am

OBJECTIVE: Examine longitudinal associations between sources of social support and social undermining for healthy eating and physical activity and weight change.

METHODS: Data are from 633 employed adults participating in a cluster-randomized multilevel weight gain prevention intervention. Primary predictors included social support and social undermining for two types of behaviors (healthy eating and physical activity) from three sources (family, friends, and coworkers) obtained via self-administered surveys. The primary outcome (weight in kg) was measured by trained staff. Data were collected at baseline, 12 months, and 24 months. Linear multivariable models examined the association of support and social undermining with weight over time, adjusting for intervention status, time, gender, age, education, and clustering of individuals within schools.

RESULTS: Adjusting for all primary predictors and covariates, friend support for healthy eating (beta = -0.15), coworker support for healthy eating (beta = -0.11), and family support for physical activity (beta = -0.032) were associated with weight reduction at 24 months (P-values < 0.05). Family social undermining for healthy eating was associated with weight gain at 24 months (beta = 0.12; P = 0.0019).

CONCLUSIONS: Among adult employees, friend and coworker support for healthy eating and family support for physical activity predicted improved weight management. Interventions that help adults navigate family social undermining of healthy eating are warranted.

Crosstalk between BRCA-Fanconi anemia and mismatch repair pathways prevents MSH2-dependent aberrant DNA damage responses

Mon, 08/10/2015 - 8:35am

Several proteins in the BRCA-Fanconi anemia (FA) pathway, such as FANCJ, BRCA1, and FANCD2, interact with mismatch repair (MMR) pathway factors, but the significance of this link remains unknown. Unlike the BRCA-FA pathway, the MMR pathway is not essential for cells to survive toxic DNA interstrand crosslinks (ICLs), although MMR proteins bind ICLs and other DNA structures that form at stalled replication forks. We hypothesized that MMR proteins corrupt ICL repair in cells that lack crosstalk between BRCA-FA and MMR pathways. Here, we show that ICL sensitivity of cells lacking the interaction between FANCJ and the MMR protein MLH1 is suppressed by depletion of the upstream mismatch recognition factor MSH2. MSH2 depletion suppresses an aberrant DNA damage response, restores cell cycle progression, and promotes ICL resistance through a Rad18-dependent mechanism. MSH2 depletion also suppresses ICL sensitivity in cells deficient for BRCA1 or FANCD2, but not FANCA. Rescue by Msh2 loss was confirmed in Fancd2-null primary mouse cells. Thus, we propose that regulation of MSH2-dependent DNA damage response underlies the importance of interactions between BRCA-FA and MMR pathways.

Mismatch repair proteins and AID activity are required for the dominant negative function of C-terminally deleted AID in class switching

Mon, 08/10/2015 - 8:35am

Activation-induced cytidine deaminase (AID) is essential for class-switch recombination (CSR) and somatic hypermutation (SHM) of Ig genes. The AID C terminus is required for CSR, but not for S-region DNA double-strand breaks (DSBs) during CSR, and it is not required for SHM. AID lacking the C terminus (DeltaAID) is a dominant negative (DN) mutant, because human patients heterozygous for this mutant fail to undergo CSR. In agreement, we show that DeltaAID is a DN mutant when expressed in AID-sufficient mouse splenic B cells. To have DN function, DeltaAID must have deaminase activity, suggesting that its ability to induce DSBs is important for the DN function. Supporting this hypothesis, Msh2-Msh6 have been shown to contribute to DSB formation in S regions, and we find in this study that Msh2 is required for the DN activity, because DeltaAID is not a DN mutant in msh2(-/-) cells. Our results suggest that the DNA DSBs induced by DeltaAID are unable to participate in CSR and might interfere with the ability of full-length AID to participate in CSR. We propose that DeltaAID is impaired in its ability to recruit nonhomologous end joining repair factors, resulting in accumulation of DSBs that undergo aberrant resection. Supporting this hypothesis, we find that the S-S junctions induced by DeltaAID have longer microhomologies than do those induced by full-length AID. In addition, our data suggest that AID binds Smu regions in vivo as a monomer.

Effect of self-referral on bone mineral density testing and osteoporosis treatment

Mon, 08/10/2015 - 8:35am

BACKGROUND: Despite national guidelines recommending bone mineral density screening with dual-energy x-ray absorptiometry (DXA) in women aged 65 years and older, many women do not receive initial screening.

OBJECTIVE: To determine the effectiveness of health system and patient-level interventions designed to increase appropriate DXA testing and osteoporosis treatment through (1) an invitation to self-refer for DXA (self-referral); (2) self-referral plus patient educational materials; and (3) usual care (UC, physician referral).

RESEARCH DESIGN: Parallel, group-randomized, controlled trials performed at Kaiser Permanente Northwest (KPNW) and Kaiser Permanente Georgia (KPG). SUBJECTS: Women aged 65 years and older without a DXA in past 5 years.

MEASURES: DXA completion rates 90 days after intervention mailing and osteoporosis medication receipt 180 days after initial intervention mailing.

RESULTS: From > 12,000 eligible women, those randomized to self-referral were significantly more likely to receive a DXA than UC (13.0%-24.1% self-referral vs. 4.9%-5.9% UC, P < 0.05). DXA rates did not significantly increase with patient educational materials. Osteoporosis was detected in a greater proportion of self-referral women compared with UC (P < 0.001). The number needed to receive an invitation to result in a DXA in KPNW and KPG regions was approximately 5 and 12, respectively. New osteoporosis prescription rates were low (0.8%-3.4%) but significantly greater among self-referral versus UC in KPNW.

CONCLUSIONS: DXA rates significantly improved with a mailed invitation to schedule a scan without physician referral. Providing women the opportunity to self-refer may be an effective, low-cost strategy to increase access for recommended osteoporosis screening.

Composite model for profiling physicians across domains of care

Mon, 08/10/2015 - 8:35am

Physician profiling methods are envisioned as a means of promoting healthcare quality by recognizing the contributions of individual physicians. Developing methods that can reliably distinguish among physicians' performance is challenging because of small sample sizes, incomplete data, and physician panel differences. In this study, we developed a hierarchical, weighted composite model to reliably compare primary care physicians across domains of care, and we demonstrated its use within a clinical system. We evaluated 199 primary care physicians from a large integrated healthcare delivery system using 19 quality and two efficiency measures taken from the Healthcare Effectiveness Data and Information Set and existing pay-for-performance programs. Individual measures were calculated, compared to benchmarks, and grouped into two composites: one focused on quality and one on efficiency. Each composite was fitted to the model, assessed for reliability (signal-to-noise ratio), and weighted to create a single summary score for each primary care physician. The quality-of-care composite had a median reliability of .98, with 99.5% of all physician reliability estimates exceeding threshold. The efficiency composite had a median reliability of .97, with 94.9% of all physician reliability estimates exceeding threshold. Our results demonstrate that reliable physician profiling is possible across care domains using a hierarchical composite model based on multiple data. The model was used to distribute incentive payouts among primary care physicians but is adaptable to many settings.

An online social network to increase walking in dog owners: a randomized trial

Mon, 08/10/2015 - 8:35am

PURPOSE: Encouraging dog walking may increase physical activity in dog owners. This cluster-randomized controlled trial investigated whether a social networking Web site (Meetup) could be used to deliver a multicomponent dog walking intervention to increase physical activity.

METHODS: Sedentary dog owners (n = 102) participated. Eight neighborhoods were randomly assigned to the Meetup condition (Meetup) or a condition where participants received monthly e-mails with content from the American Heart Association regarding increasing physical activity. The Meetup intervention was delivered over 6 months and consisted of newsletters, dog walks, community events, and an activity monitor. The primary outcome was steps; secondary outcomes included social support for walking, sense of community, perceived dog walking outcomes, barriers to dog walking, and feasibility of the intervention.

RESULTS: Mixed-model analyses examined change from baseline to postintervention (6 months) and whether change in outcomes differed by condition. Daily steps increased over time (P = 0.04, d = 0.28), with no differences by condition. The time-condition interaction was significant for the perceived outcomes of dog walking (P = 0.04, d = 0.40), such that the Meetup condition reported an increase in the perceived positive outcomes of dog walking, whereas the American Heart Association condition did not. Social support, sense of community, and dog walking barriers did not significantly change. Meetup logins averaged 58.38 per week (SD, 11.62). Within 2 months of the intervention ending, organization of the Meetup groups transitioned from the study staff to Meetup members.

CONCLUSIONS: Results suggest that a Meetup group is feasible for increasing physical activity in dog owners. Further research is needed to understand how to increase participation in the Meetup group and facilitate greater connection among dog owners.

Comparison of trends in US health-related quality of life over the 2000s using the SF-6D, HALex, EQ-5D, and EQ-5D visual analog scale versus a broader set of symptoms and impairments

Mon, 08/10/2015 - 8:35am

BACKGROUND: A number of instruments have been developed to measure health-related quality of life (HRQoL), differing in the health domains covered and their scoring. Although few such measures have been consistently included in US national health surveys over time, the surveys have included data on a broad range of symptoms and impairments, which enables the tracking of population health trends.

OBJECTIVES: To compare trends in HRQoL as measured using existing instruments versus using a broader range of symptoms and impairments collected in multiple years of nationally representative data.

DATA AND MEASURES: Data were from the 2000-2010 Medical Expenditure Panel Survey, which is nationally representative of the noninstitutionalized US population. Level of and trends in HRQoL derived from a broad range of survey symptoms and impairments (SSI) was compared with HRQoL from the SF-6D, the HALex, and, between 2000 and 2003, the EuroQol-5D (EQ-5D) and EQ-5D Visual Analog Scale.

RESULTS: Trends in HRQoL were similar using different measures. The SSI scores correlated 0.66-0.80 with scores from other measures and mean SSI scores were between those of other measures. Scores from all HRQoL measures declined similarly with increasing age and with the presence of comorbid conditions.

CONCLUSIONS: Measuring HRQoL using a broader range of symptoms and impairments than those in a single instrument yields population health trends similar to those from other measures while making maximum use of existing data and providing rich detail on the factors underlying change.

Facilitators and barriers to the active participation of clients with serious mental illnesses in medication decision making: the perceptions of young adult clients

Mon, 08/10/2015 - 8:35am

The active participation of young adults with serious mental illnesses (SMI) in making decisions about their psychotropic medications is beneficial to their care quality and overall health. Many however report not expressing treatment preferences to psychiatrists. Qualitative methods were used to interview 24 young adults with SMI about their experiences making medication decisions with their psychiatrists. An inductive analytic approach was taken to identifying conceptual themes in the transcripts. Respondents reported that the primary facilitators to active participation were the psychiatrist's openness to the client's perspective, the psychiatrist's availability outside of office hours, the support of other mental health providers, and personal growth and self-confidence of the young adults. The primary barriers to active participation reported were the resistance of the psychiatrist, the lack of time for consultations, and limited client self-efficacy. Young adults with SMI can be active participants in making decisions about their psychiatric treatment.