Abdominal aortic aneurysm screening: how many life years lost from underuse of the medicare screening benefit?

BACKGROUND: Since 2007, Medicare has provided one-time abdominal aortic aneurysm (AAA) screening for men with smoking history, and men and women with a family history of AAA as part of its Welcome to Medicare visit. OBJECTIVE: We examined utilization of the new AAA screening benefit and estimated how increased utilization could influence population health as measured by life years gained. Additionally, we explored the impact of expanding screening to women with smoking history. DESIGN: Analysis of Medicare claims and a simulation model to estimate the effects of screening, using published data for parameter estimates. SETTING: AAA screening in the primary care setting. PATIENTS: Newly-enrolled Medicare beneficiaries aged 65 years, with smoking history or family history of AAA. MAIN MEASURES: Life expectancy, 10-year survival rates. KEY RESULTS: Medicare data revealed low utilization of AAA screening, under 1% among those eligible. We estimate that screening could increase life expectancy per individual invited to screening for men with smoking history (0.11 years), with family history of AAA (0.17 years), and women with family history (0.08 years), and smoking history (0.09 years). Average gains of 131 life years per 1,000 persons screened for AAA compare favorably with the grade B United States Preventive Services Task Force (USPSTF) recommendation for breast cancer screening, which yields 95-128 life years per 1,000 women screened. These findings were robust over a range of scenarios. LIMITATIONS: The simulation results reflect assumptions regarding AAA prevalence, treatment, and outcomes in specific populations based on published research and US survey data. Published data on women were limited. CONCLUSIONS: The Welcome to Medicare and AAA screening benefits have been underutilized. Increasing utilization of AAA screening would yield substantial gains in life expectancy. Expanding screening to women with smoking history also has the potential for substantial health benefits.

The O7 antigen of Stenotrophomonas maltophilia is a linear D-rhamnan with a trisaccharide repeating unit that is also present in polymers for some Pseudomonas and Burkholderia species.

The O antigen polymer recovered from the reference strain for Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia serogroup O7, after mild acid hydrolysis of the lipopolysaccharide, was constructed from D-rhamnose. By means of chemical degradations and NMR studies, the repeating unit of the polymer was shown to be a linear trisaccharide with the structure -->2)-alpha-D-Rhap-(1-->3)-alpha-D-Rhap-(1-->3)-alpha-D-R hap-(1-->. The same repeating unit is present in the common antigen of Pseudomonas aeruginosa and in O antigens from some pathovars of Pseudomonas syringae and a strain of Burkholderia (Pseudomonas) cepacia.

Effect of density on magnitude of directional selection on seed mass and emergence time in Plantago wrightiana Dcne. (Plantaginaceae).

Although population density is believed to be an important factor influencing evolutionary processes, surprisingly few studies have documented the existence or nature of density-dependent selection. We quantified the effects of density on directional selection on seed mass (the mass of a sown seed) and emergence time in the greenhouse and field for the annual plant Plantago wrightiana. In the greenhouse, we quantified selection on seed mass and emergence time at each of five planting densities (1 m-2 to 10,000 m-2) using the relationship between final plant mass and each trait at each density. We observed no significant selection on either seed mass or emergence time when plants were grown alone. At all higher densities, there was significant selection favoring early emergence and large seed mass, but there were no significant differences among the selection gradients determined at densities greater than individually grown plants. In the field, we detected no relationship between the magnitude of selection for early emergence and density. Our results suggest that selection on seed mass and time of emergence is density dependent, but the relationship between density and the magnitude of directional selection on these traits is not continuously increasing. Over broad ranges of density in the greenhouse and in the field, there was no detectable relationship between density and the magnitude of directional selection.

Structure of the O6 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia.

A polysaccharide containing D-xylose, L-rhamnose, and N-acetyl-D-glucosamine was released on mild acid hydrolysis of the lipopolysaccharide extracted from defatted cell walls of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia strain 557, the reference strain for serotype O6. By means of NMR spectroscopy and chemical degradations, the repeating unit of the polymer was identified as a branched trisaccharide with the structure shown. [formula: see text]

Structure of the O20 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia.

The O-antigen polymer recovered from the reference strain for Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia serogroup O20, by mild acid hydrolysis of the lipopolysaccharide, was found to contain D-rhamnose and D-mannose. By means of chemical degradations and NMR studies, the repeating-unit of the polymer was deduced to be a linear tetrasaccharide with the structure shown. -->2)-alpha-D-Manp-(1-->3)-beta-D-Rhap-(1-->2)-alpha-D-Rh ap-(1-->2)-alpha-D- Rhap-(1-->.

Structures of the O4 and O18 antigens of Stenotrophomonas maltophilia: a case of enantiomeric repeating units.

The O-specific side-chain polymers of lipopolysaccharides from the reference strains for Stenotrophomonas maltophilia serogroups 04 and O18 are both xylosylated rhamnans. In the 04 polymer, both sugar components are the D isomers, whereas the O18 polymer contains only the L isomers. By means of NMR spectroscopy, methylation analysis and Smith degradation, the repeating unit of the 04 polymer was identified as a doubly-branched pentasaccharide of the structure shown below. The O18 polymer is based on the enantiomeric pentasaccharide, but the xylosyl substituent at the 4-position is apparently absent from some units. The polymers closely resemble the O antigens found in Xanthomonas campestris pathovars. [structure: see text]

Structure of the O16 antigen of Stenotrophomonas maltophilia.

A polysaccharide containing D-ribose, N-acetyl-D-glucosamine, and N-acetyl-D-mannosamine was isolated from the phenol-soluble lipopolysaccharide extracted from defatted cell walls of the reference strain (560) for serogroup O16 of Stenotrophomonas maltophilia. The results of methylation analysis, chemical degradations, and NMR spectroscopy showed that the polysaccharide is based on a branched trisaccharide repeating-unit of the structure shown below. Although ribose was absent from about half of the units in the isolated polymer, the regularity and spacing of the ladder observed on SDS-PAGE of the parent lipopolysaccharide indicate that this was an artefact of the mild acid hydrolysis used to release the polymer. On the other hand, the effects of mild alkaline hydrolysis on the polymer indicated partial O-acetylation. [structure: see text]

Structure of the O2 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia.

An O antigenic polymer containing L-rhamnose, D-mannose, and L-xylose was isolated from the lipopolysaccharide present in the reference strain for Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia serogroup O2, by mild acid hydrolysis and gel-permeation chromatography. By means of NMR spectroscopy and chemical degradations, the polysaccharide was found to be based on a branched trisaccharide repeating-unit of the structure shown. [formula: see text].

Structure of the O10 antigen of Stenotrophomonas (Xanthomonas) maltophilia.

A polysaccharide containing L-rhamnose and L-xylose was isolated from the lipopolysaccharide extracted from the cell walls of the reference strain for Stenotrophomonas (Xanthomonas) maltophilia serogroup O10. By means of NMR studies and methylation analysis, the repeating unit of the polymer was identified as a branched tetrasaccharide of the structure shown. [formula: see text]

Structure of the O19 antigen of Xanthomonas maltophilia.

The O-specific polymer from a strain of Xanthomonas maltophilia O19 contains D-glucose, L-rhamnose, and D-fucose. By means of chemical degradations and NMR studies, the repeating unit of the polymer was determined to be a branched tetrasaccharide of the structure shown. [formula: see text]

Structure of the O3 antigen of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia.

The O antigen isolated from the lipopolysaccharide of a strain of Stenotrophomonas (Xanthomonas or Pseudomonas) maltophilia serogroup O3 was found to contain 4-acetamido-4,6-dideoxy-D-galactose, D-fucose, and N-acetyl-D-glucosamine. By means of chemical degradations and NMR spectroscopy the repeating unit of the O-specific polymer was determined to be a branched trisaccharide repeating-unit of the structure shown.

A fat lot of good: balance and trends in fat intake in children with cystic fibrosis.

BACKGROUND: The fundamental nutritional treatment of a high fat diet for cystic fibrosis (CF) is established and essentially unchanged in the last 25 years. However, recent concerns have emerged regarding the potential risks of such a diet. We investigated the diets of children with CF to determine the source of energy, energy imbalance, and changing trends of fat intake. METHOD: In a prospective longitudinal study over 8 years at a single paediatric CF clinic three-day food diaries that included supplementary nutrition (SN) either as enteral feeds or oral nutritional supplements (ONS), were analysed annually. Influence of year on percent energy by type (fat, carbohydrate and protein) and on fat component: saturated (SFA); monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) was examined. RESULTS: 136 food diaries were analysed in 27 children (age range 1-18 years). 51 (37%) food diaries included SN (enteral feeds n=15 and ONS n=36). Mean energy intake was 1726 Kcals (oral diet alone) and 2245 Kcals (including SN). Percent energy from macronutrients did not change significantly over time (protein p=0.06; carbohydrate p=0.44; fat p=0.07) and remained within recommended levels. Mean caloric contribution from fat was 38.7% from oral diet alone and 37.8% including SN. Percent energy derived from SFA remained statistically unchanged (SFA p=0.57) but fell from MUFA (p=0.05) and PUFA (p=0.004). Mean SFA consistently contributed >134% (mean 158%) of reference nutrient intake and mean PUFA intake <100% (92%). CONCLUSION: Macronutrient intakes did not change significantly in our population of CF children, but there was a consistent imbalance of fat-sources with over-dependence on saturated fats which, in the context of increased survival in CF may potentially increase risk of cardiovascular disease. Further studies are needed to confirm our findings, investigate consequences of fat imbalance and guide clearer advice regarding appropriate proportions of sources of fat for CF patients.

Natural selection, evolvability and bias due to environmental covariance in the field in an annual plant.

Estimates of the form and magnitude of natural selection based on phenotypic relationships between traits and fitness measures can be biased when environmental factors influence both relative fitness and phenotypic trait values. I quantified genetic variances and covariances, and estimated linear and quadratic selection coefficients, for seven traits of an annual plant grown in the field. For replicates of 50 paternal half-sib families, coefficients of selection were calculated both for individual phenotypic values of the traits and for half-sib family mean values. The potential for evolutionary response was supported by significant heritability and phenotypic directional selection for several traits but contradicted by the absence of significant genetic variation for fitness estimates and evidence of bias in phenotypic selection coefficients due to environmental covariance for at least two of the traits analysed. Only studies of a much wider range of organisms and traits will reveal the frequency and extent of such bias.