bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms Controlling the Initial Stiffness of Frozen Sand
Authors: Da Re Gregory , Germaine John T. , Ladd Charles C.
Published: August 2013

This paper presents an extensive laboratory testing program undertaken to study the influence of interface bonding and particle size, roughness, and shape on the Young's modulus of ice-saturated frozen sand in triaxial compression. The program also included the influence of particle stiffness by testing plastic beads having a much lower modulus than the quartz-based sand particles. The study used a high-pressure, low-temperature, automated triaxial compression testing system having an on-specimen device capable of consistently measuring displacements of less than 0.1 μm, corresponding to strains of less than 0.0002 %. Very precise temperature and strain-rate control systems contributed to the reliability of the small strain measurements at confining pressures up to 12.5 MPa. Experimental findings show that the Young's modulus of ice-saturated frozen materials varies significantly with particle modulus and increases slightly with particle volume fraction but does not change with confining pressure, strain rate, or temperature. The modulus, however, depends on the ability of the system to transfer interfacial shear stresses between the particle and ice matrix in the form of both adhesion and mechanical interference. In natural frozen sands, the shear stress is transferred primarily through surface roughness and particle angularity, and consequently the adhesional bond between the ice matrix and the sand particles is of secondary importance. In contrast, adhesional bonding dominates in frozen systems composed of relatively smooth spherical particles. Reinforcement theories for two phase particulate composite materials can be used to model the Young's modulus of ice-saturated frozen natural sand.
Characteristics of Chicago Blue Clay Subjected to a Freeze–Thaw Cycle
Authors: Swan Christopher W. , Grant Alex , Kody Alyssa
Published: August 2013

This paper presents the preliminary results of a laboratory study on the impact of one freeze–thaw cycle on the engineering properties of natural samples of Chicago Blue Clay (CBC). Freezing was performed in a closed system with freezing occurring simultaneously in all directions. Two types of consolidation tests were performed: incremental loading and long-term compression under a constant load. These tests were performed on specimens subjected to a cycle of freeze–thaw with results compared to tests on CBC in its natural state. For constant load consolidation tests, freezing and subsequent thaw of specimens was performed under the applied stress. Additionally, the Atterberg limits of CBC, in its natural state and after one freeze–thaw cycle, were also determined. Based on the test results in this study, it is clear that one cycle of freezing and thawing impacts both the consolidation behavior and limits of the samples. Specifically, for both the incremental and constant loading tests there is a significant increase (between 25 % and 40 %) in settlement during consolidation versus results of tests on CBC in its natural state. There is also a notable increase in the virgin compression ratio (Cc) and coefficient of consolidation (cv) upon thawing. Results of Atterberg limits indicate a decrease in the CBC's liquid limit that explains, in part, the increase in cv. Overall, the results indicate that the freezing and subsequent thawing of CBC has a severe impact on its consolidation behavior. The writers recommend that more testing be performed to verify and expand on the results determined from this preliminary evaluation.
Investigation of the Dynamic Behaviors of Frozen Saline Silt with the Use of a Spherical Stamp
Authors: Sinitsyn Anatoly
Published: August 2013

The objective of this work was to study the dynamic interactions between a spherical indenter and frozen soil. Indentation via a spherical stamp was used for various dynamic applications with equal kinetic energy. This research is an attempt to add to the theoretical background for pile driving in permafrost. The focus is on the supposition that pile driving performed by a heavier hammer falling with a low velocity is more efficient than that done by a light hammer falling from a greater height at an equal kinetic energy. Monitoring of the force acting on the stamp during dynamic loading was performed for the first time with the use of a thin, flexible sensor placed between the stamp and the frozen soil sample. A plastic ball with a diameter of 25 mm was used as the spherical stamp, and the dynamic load on the stamp was provided by a falling dead weight. Artificial samples of frozen saline silt with a height of 35 mm and a diameter of 70 mm were used in the tests. The results show that the deformation behavior of frozen saline silt was significantly dependent on the impulse at a constant kinetic energy, and greater deformation was observed with increasing temperature in the range of the freezing point. An analytical solution that was previously used for ice was found to be suitable for the description of the investigated dynamic processes.
Frozen-Soil Classification With Index Testing
Authors: Still Benjamin , Proskin Sam , Zubeck Hannele , Yang Zhaohui
Published: August 2013

Classification of frozen soils was first developed by the U.S. Army Corps of Engineers' Cold Regions Research and Engineering Laboratory (CRREL) together with the Division of Building Research, National Research Council, Canada. This visual method of classification was adopted by ASTM in 1983 as designation D4083, currently ASTM D4083-07: Standard Practice for Description of Frozen Soils (Visual-Manual Procedure), Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA. The current visual classification standard does not use any engineering index testing to classify the soils. This leaves the engineer with a qualitative assessment of soil–ice mass type, strength, and stability in which a more conservative and expensive design may be considered and even worse, an under design may occur. The engineer is in need of some index properties that can be readily measured to provide a more objective method to classify the soil–ice mass. This paper investigates the relationship between water content and density to frozen-soil classification. It was found that the water/ice content and dry density within the same frozen-soil class varies significantly, which may lead to different mechanical behavior or thaw settlement. Therefore, reporting the water (ice) content and frozen-soil density together with the frozen-soil classification helps the engineer to better evaluate thaw settlement and assess need for further testing.
Strength and Creep Properties of a Frozen Coastal Sand in Saltwater
Authors: Vitton Stanley J. , Muszynski Mark R.
Published: August 2013

In 1998, the Port of Los Angeles contracted to have a force main under their primary shipping channel relocated from a depth of 13 m to 26 m. Access shafts were excavated using frozen ground technology to a depth of 26 m, with the frozen ground used for support of the excavation. When the shaft was within 1 m of the required depth, water started to enter into the excavation. Six hours later, the shaft collapsed. An investigation was conducted into the strength of the frozen soil. Unconfined compression strength tests were conducted at strain rates of 0.1 % and 1 %. The samples were saturated with water from the shaft, which had a salt concentration measured as equal to that of seawater. Short-term compressive strength was measured between 1300 and 1900 kPa. Constant stress creep tests were also conducted, indicating a strength of about 760 kPa. All testing was conducted at a temperature of −10°C.
A Whole-Genome DNA Marker Map for Cotton Based on the D-Genome Sequence of Gossypium raimondii L.
Authors: Wang Zining , Zhang Dong , Wang Xiyin , Tan Xu , Guo Hui , Paterson Andrew H
Published: August 2013

We constructed a very-high-density, whole-genome marker map (WGMM) for cotton by using 18,597 DNA markers corresponding to 48,958 loci that were aligned to both a consensus genetic map and a reference genome sequence. The WGMM has a density of one locus per 15.6 kb, or an average of 1.3 loci per gene. The WGMM was anchored by the use of colinear markers to a detailed genetic map, providing recombinational information. Mapped markers occurred at relatively greater physical densities in distal chromosomal regions and lower physical densities in the central regions, with all 1 Mb bins having at least nine markers. Hotspots for quantitative trait loci and resistance gene analog clusters were aligned to the map and DNA markers identified for targeting of these regions of high practical importance. Based on the cotton D genome reference sequence, the locations of chromosome structural rearrangements plotted on the map facilitate its translation to other Gossypium genome types. The WGMM is a versatile genetic map for marker assisted breeding, fine mapping and cloning of genes and quantitative trait loci, developing new genetic markers and maps, genome-wide association mapping, and genome evolution studies.
Insights into the Evolution of Cotton Diploids and Polyploids from Whole-Genome Re-sequencing
Authors: Page Justin T , Huynh Mark D , Liechty Zach S , Grupp Kara , Stelly David , Hulse Amanda M , Ashrafi Hamid , Van Deynze Allen , Wendel Jonathan F , Udall Joshua A
Published: August 2013

Understanding the composition, evolution, and function of the Gossypium hirsutum (cotton) genome is complicated by the joint presence of two genomes in its nucleus (AT and DT genomes). These two genomes were derived from progenitor A-genome and D-genome diploids involved in ancestral allopolyploidization. To better understand the allopolyploid genome, we re-sequenced the genomes of extant diploid relatives that contain the A1 (Gossypium herbaceum), A2 (Gossypium arboreum), or D5 (Gossypium raimondii) genomes. We conducted a comparative analysis using deep re-sequencing of multiple accessions of each diploid species and identified 24 million SNPs between the A-diploid and D-diploid genomes. These analyses facilitated the construction of a robust index of conserved SNPs between the A-genomes and D-genomes at all detected polymorphic loci. This index is widely applicable for read mapping efforts of other diploid and allopolyploid Gossypium accessions. Further analysis also revealed locations of putative duplications and deletions in the A-genome relative to the D-genome reference sequence. The approximately 25,400 deleted regions included more than 50% deletion of 978 genes, including many involved with starch synthesis. In the polyploid genome, we also detected 1,472 conversion events between homoeologous chromosomes, including events that overlapped 113 genes. Continued characterization of the Gossypium genomes will further enhance our ability to manipulate fiber and agronomic production of cotton.
Comparing Zinc Finger Nucleases and Transcription Activator-Like Effector Nucleases for Gene Targeting in Drosophila
Authors: Beumer Kelly J , Trautman Jonathan K , Christian Michelle , Dahlem Timothy J , Lake Cathleen M , Hawley R Scott , Grunwald David J , Voytas Daniel F , Carroll Dana
Published: August 2013

Zinc-finger nucleases have proven to be successful as reagents for targeted genome manipulation in Drosophila melanogaster and many other organisms. Their utility has been limited, however, by the significant failure rate of new designs, reflecting the complexity of DNA recognition by zinc fingers. Transcription activator-like effector (TALE) DNA-binding domains depend on a simple, one-module-to-one-base-pair recognition code, and they have been very productively incorporated into nucleases (TALENs) for genome engineering. In this report we describe the design of TALENs for a number of different genes in Drosophila, and we explore several parameters of TALEN design. The rate of success with TALENs was substantially greater than for zinc-finger nucleases , and the frequency of mutagenesis was comparable. Knockout mutations were isolated in several genes in which such alleles were not previously available. TALENs are an effective tool for targeted genome manipulation in Drosophila.
Characterization of Two ENU-Induced Mutations Affecting Mouse Skeletal Morphology
Authors: Dauphinee Shauna M , Eva Megan M , Yuki Kyoko E , Herman Melissa , Vidal Silvia M , Malo Danielle
Published: August 2013

Using the N-ethyl-N-nitrosourea (ENU) mutagenesis screen, we have identified two skeletal morphology mutants, Skm1 and Skm2. Positional cloning and candidate gene sequencing localized the causative point mutations within the genes coding for natriuretic peptide receptor C (NPR-C) and filamin b (FLNB), respectively. Mice that carry a mutation in Npr3 exhibit a skeletal overgrowth phenotype, resulting in an elongated body and kyphosis. Skm2 mice, carrying a mutation in Flnb, present with scoliosis and lordosis. These mutant mice will serve as useful models for the study of vertebral malformations.
Functional Conservation of Gsdma Cluster Genes Specifically Duplicated in the Mouse Genome
Authors: Tanaka Shigekazu , Mizushina Youichi , Kato Yoriko , Tamura Masaru , Shiroishi Toshihiko
Published: August 2013

Mouse Gasdermin A3 (Gsdma3) is the causative gene for dominant skin mutations exhibiting alopecia. Mouse has two other Gsdma3-related genes, Gsdma and Gsdma2, whereas human and rat have only one related gene. To date, no skin mutation has been reported for human GSDMA and rat Gsdma as well as mouse Gsdma and Gsdma2. Therefore, it is possible that only Gsdma3 has gain-of-function type mutations to cause dominant skin phenotype. To elucidate functional divergence among the Gsdma-related genes in mice, and to infer the function of the human and rat orthologs, we examined in vivo function of mouse Gsdma by generating Gsdma knockout mice and transgenic mice that overexpress wild-type Gsdma or Gsdma harboring a point mutation (Alanine339Threonine). The Gsdma knockout mice shows no visible phenotype, indicating that Gsdma is not essential for differentiation of epidermal cells and maintenance of the hair cycle, and that Gsdma is expressed specifically both in the inner root sheath of hair follicles and in suprabasal cell layers, whereas Gsdma3 is expressed only in suprabasal layers. By contrast, both types of the transgenic mice exhibited epidermal hyperplasia resembling the Gsdma3 mutations, although the phenotype depended on the genetic background. These results indicate that the mouse Gsdma and Gsdma3 genes share common function to regulate epithelial maintenance and/or homeostasis, and suggest that the function of human GSDMA and rat Gsdma, which are orthologs of mouse Gsdma, is conserved as well.
Identification of a Novel Polymorphism in X-Linked Sterol-4-Alpha-Carboxylate 3-Dehydrogenase (Nsdhl) Associated with Reduced High-Density Lipoprotein Cholesterol Levels in I/LnJ Mice
Authors: Bautz David J , Broman Karl W , Threadgill David W
Published: August 2013

Loci controlling plasma lipid concentrations were identified by performing a quantitative trait locus analysis on genotypes from 233 mice from a F2 cross between KK/HlJ and I/LnJ, two strains known to differ in their high-density lipoprotein (HDL) cholesterol levels. When fed a standard diet, HDL cholesterol concentration was affected by two significant loci, the Apoa2 locus on Chromosome (Chr) 1 and a novel locus on Chr X, along with one suggestive locus on Chr 6. Non-HDL concentration also was affected by loci on Chr 1 and X along with a suggestive locus on Chr 3. Additional loci that may be sex-specific were identified for HDL cholesterol on Chr 2, 3, and 4 and for non-HDL cholesterol on Chr 5, 7, and 14. Further investigation into the potential causative gene on Chr X for reduced HDL cholesterol levels revealed a novel, I/LnJ-specific nonsynonymous polymorphism in Nsdhl, which codes for sterol-4-alpha-carboxylate 3-dehydrogenase in the cholesterol synthesis pathway. Although many lipid quantitative trait locus have been reported previously, these data suggest there are additional genes left to be identified that control lipid levels and that can provide new pharmaceutical targets.
Drosophila Embryonic Cell-Cycle Mutants
Authors: Unhavaithaya Yingdee , Park Eugenia A , Royzman Irena , Orr-Weaver Terry L
Published: August 2013

Nearly all cell division mutants in Drosophila were recovered in late larval/pupal lethal screens, with less than 10 embryonic lethal mutants identified, because larval development occurs without a requirement for cell division. Only cells in the nervous system and the imaginal cells that generate the adult body divide during larval stages, with larval tissues growing by increasing ploidy rather than cell number. Thus, most mutants perturbing mitosis or the cell cycle do not manifest a phenotype until the adult body differentiates in late larval and pupal stages. To identify cell-cycle components whose maternal pools are depleted in embryogenesis or that have specific functions in embryogenesis, we screened for mutants defective in cell division during embryogenesis. Five new alleles of Cyclin E were recovered, ranging from a missense mutation that is viable to stop codons causing embryonic lethality. These permitted us to investigate the requirements for Cyclin E function in neuroblast cell fate determination, a role previously shown for a null Cyclin E allele. The mutations causing truncation of the protein affect cell fate of the NB6-4 neuroblast, whereas the weak missense mutation has no effect. We identified mutations in the pavarotti (pav) and tumbleweed (tum) genes needed for cytokinesis by a phenotype of large and multinucleate cells in the embryonic epidermis and nervous system. Other mutations affecting the centromere protein CAL1 and the kinetochore protein Spc105R caused mitotic defects in the nervous system.
When Females Produce Sperm: Genetics ofC. elegansHermaphrodite Reproductive Choice
Authors: Bahrami Adam K , Zhang Yun
Published: August 2013

Reproductive behaviors have manifold consequences on evolutionary processes. Here, we explore mechanisms underlying female reproductive choice in the nematode Caenorhabditis elegans, a species in which females have evolved the ability to produce their own self-fertilizing sperm, thereby allowing these "hermaphrodites" the strategic choice to self-reproduce or outcross with males. We report that hermaphrodites of the wild-type laboratory reference strain N2 favor self-reproduction, whereas a wild isolate CB4856 (HW) favors outcrossing. To characterize underlying neural mechanisms, we show that N2 hermaphrodites deficient in mechanosensation or chemosensation (e.g., mec-3 and osm-6 mutants) exhibit high mating frequency, implicating hermaphrodite perception of males as a requirement for low mating frequency. Within chemosensory networks, we find opposing roles for different sets of neurons that express the cyclic GMP-gated nucleotide channel, suggesting both positive and negative sensory-mediated regulation of hermaphrodite mating frequency. We also show that the ability to self-reproduce negatively regulates hermaphrodite mating. To map genetic variation, we created recombinant inbred lines and identified two QTL that explain a large portion of N2 × HW variation in hermaphrodite mating frequency. Intriguingly, we further show that ∼40 wild isolates representing C. elegans global diversity exhibit extensive and continuous variation in hermaphrodite reproductive outcome. Together, our findings demonstrate that C. elegans hermaphrodites actively regulate the choice between selfing and crossing, highlight the existence of natural variation in hermaphrodite choice, and lay the groundwork for molecular dissection of this evolutionarily important trait.
Population Growth Inflates the Per-Individual Number of Deleterious Mutations and Reduces Their Mean Effect
Authors: Gazave Elodie , Chang Diana , Clark Andrew G , Keinan Alon
Published: August 2013

This study addresses the question of how purifying selection operates during recent rapid population growth such as has been experienced by human populations. This is not a straightforward problem because the human population is not at equilibrium: population genetics predicts that, on the one hand, the efficacy of natural selection increases as population size increases, eliminating ever more weakly deleterious variants; on the other hand, a larger number of deleterious mutations will be introduced into the population and will be more likely to increase in their number of copies as the population grows. To understand how patterns of human genetic variation have been shaped by the interaction of natural selection and population growth, we examined the trajectories of mutations with varying selection coefficients, using computer simulations. We observed that while population growth dramatically increases the number of deleterious segregating sites in the population, it only mildly increases the number carried by each individual. Our simulations also show an increased efficacy of natural selection, reflected in a higher fraction of deleterious mutations eliminated at each generation and a more efficient elimination of the most deleterious ones. As a consequence, while each individual carries a larger number of deleterious alleles than expected in the absence of growth, the average selection coefficient of each segregating allele is less deleterious. Combined, our results suggest that the genetic risk of complex diseases in growing populations might be distributed across a larger number of more weakly deleterious rare variants.
Rate of Adaptation in Sexuals and Asexuals: A Solvable Model of the Fisher–Muller Effect
Authors: Park Su-Chan , Krug Joachim
Published: August 2013

The adaptation of large asexual populations is hampered by the competition between independently arising beneficial mutations in different individuals, which is known as clonal interference. In classic work, Fisher and Muller proposed that recombination provides an evolutionary advantage in large populations by alleviating this competition. Based on recent progress in quantifying the speed of adaptation in asexual populations undergoing clonal interference, we present a detailed analysis of the Fisher–Muller mechanism for a model genome consisting of two loci with an infinite number of beneficial alleles each and multiplicative (nonepistatic) fitness effects. We solve the deterministic, infinite population dynamics exactly and show that, for a particular, natural mutation scheme, the speed of adaptation in sexuals is twice as large as in asexuals. This result is argued to hold for any nonzero value of the rate of recombination. Guided by the infinite population result and by previous work on asexual adaptation, we postulate an expression for the speed of adaptation in finite sexual populations that agrees with numerical simulations over a wide range of population sizes and recombination rates. The ratio of the sexual to asexual adaptation speed is a function of population size that increases in the clonal interference regime and approaches 2 for extremely large populations. The simulations also show that the imbalance between the numbers of accumulated mutations at the two loci is strongly suppressed even by a small amount of recombination. The generalization of the model to an arbitrary number L of loci is briefly discussed. If each offspring samples the alleles at each locus from the gene pool of the whole population rather than from two parents, the ratio of the sexual to asexual adaptation speed is approximately equal to L in large populations. A possible realization of this scenario is the reassortment of genetic material in RNA viruses with L genomic segments.
Targeted Heritable Mutation and Gene Conversion by Cas9-CRISPR in Caenorhabditis elegans
Authors: Katic Iskra , Großhans Helge
Published: August 2013

We have achieved targeted heritable genome modification in Caenorhabditis elegans by injecting mRNA of the nuclease Cas9 and Cas9 guide RNAs. This system rapidly creates precise genomic changes, including knockouts and transgene-instructed gene conversion.
Selecting Informative Traits for Multivariate Quantitative Trait Locus Mapping Helps to Gain Optimal Power
Authors: Cheng Riyan , Borevitz Justin , Doerge R W
Published: August 2013

A major consideration in multitrait analysis is which traits should be jointly analyzed. As a common strategy, multitrait analysis is performed either on pairs of traits or on all of traits. To fully exploit the power of multitrait analysis, we propose variable selection to choose a subset of informative traits for multitrait quantitative trait locus (QTL) mapping. The proposed method is very useful for achieving optimal statistical power for QTL identification and for disclosing the most relevant traits. It is also a practical strategy to effectively take advantage of multitrait analysis when the number of traits under consideration is too large, making the usual multivariate analysis of all traits challenging. We study the impact of selection bias and the usage of permutation tests in the context of variable selection and develop a powerful implementation procedure of variable selection for genome scanning. We demonstrate the proposed method and selection procedure in a backcross population, using both simulated and real data. The extension to other experimental mapping populations is straightforward.
Identification of Mob2, a Novel Regulator of Larval Neuromuscular Junction Morphology, in Natural Populations of Drosophila melanogaster
Authors: Campbell Megan , Ganetzky Barry
Published: August 2013

Although evolutionary changes must take place in neural connectivity and synaptic architecture as nervous systems become more complex, we lack understanding of the general principles and specific mechanisms by which these changes occur. Previously, we found that morphology of the larval neuromuscular junction (NMJ) varies extensively among different species of Drosophila but is relatively conserved within a species. To identify specific genes as candidates that might underlie phenotypic differences in NMJ morphology among Drosophila species, we performed a genetic analysis on one of two phenotypic variants we found among 20 natural isolates of Drosophila melanogaster. We discovered genetic polymorphisms for both positive and negative regulators of NMJ growth segregating within the variant line. Focusing on one subline, that displayed NMJ overgrowth, we mapped the phenotype to Mob2 [Monopolar spindle (Mps) one binding protein 2)], a gene encoding a Nuclear Dbf2 (Dumbbell formation 2)-Related (NDR) kinase activator. We confirmed this identification by transformation rescue experiments and showed that presynaptic expression of Mob2 is necessary and sufficient to regulate NMJ growth. Mob2 interacts in a dominant, dose-dependent manner with tricornered but not with warts, to cause NMJ overgrowth, suggesting that Mob2 specifically functions in combination with the former NDR kinase to regulate NMJ development. These results demonstrate the feasibility and utility of identifying genetic variants affecting NMJ morphology in natural populations of Drosophila. These variants can lead to discovery of new genes and molecular mechanisms that regulate NMJ development while also providing new information that can advance our understanding of mechanisms that underlie nervous system evolution.
Highly Efficient Targeted Mutagenesis in Mice Using TALENs
Authors: Panda Sudeepta Kumar , Wefers Benedikt , Ortiz Oskar , Floss Thomas , Schmid Bettina , Haass Christian , Wurst Wolfgang , Kühn Ralf
Published: August 2013

Targeted mouse mutants are instrumental for the analysis of gene function in health and disease. We recently provided proof-of-principle for the fast-track mutagenesis of the mouse genome, using transcription activator-like effector nucleases (TALENs) in one-cell embryos. Here we report a routine procedure for the efficient production of disease-related knockin and knockout mutants, using improved TALEN mRNAs that include a plasmid-coded poly(A) tail (TALEN-95A), circumventing the problematic in vitro polyadenylation step. To knock out the C9orf72 gene as a model of frontotemporal lobar degeneration, TALEN-95A mutagenesis induced sequence deletions in 41% of pups derived from microinjected embryos. Using TALENs together with mutagenic oligodeoxynucleotides, we introduced amyotrophic lateral sclerosis patient-derived missense mutations in the fused in sarcoma (Fus) gene at a rate of 6.8%. For the simple identification of TALEN-induced mutants and their progeny we validate high-resolution melt analysis (HRMA) of PCR products as a sensitive and universal genotyping tool. Furthermore, HRMA of off-target sites in mutant founder mice revealed no evidence for undesired TALEN-mediated processing of related genomic sequences. The combination of TALEN-95A mRNAs for enhanced mutagenesis and of HRMA for simplified genotyping enables the accelerated, routine production of new mouse models for the study of genetic disease mechanisms.
Pneumococcal Meningitis in Children: Epidemiology, Serotypes, and Outcomes From 1997–2010 in Utah
Authors: Stockmann Chris , Ampofo Krow , Byington Carrie L. , Filloux Francis , Hersh Adam L. , Blaschke Anne J. , Cowan Priscilla , Korgenski Kent , Mason Edward O. , Pavia Andrew T.
Published: August 2013

BACKGROUND:

After licensure of the 7-valent pneumococcal conjugate vaccine (PCV7) in the United States in 2000, the incidence of pediatric pneumococcal meningitis decreased significantly. However, cases continue to occur. It is unknown whether meningitis due to PCV7 and non-PCV7 serotypes causes similar morbidity and mortality.

METHODS:

We performed a retrospective cohort study of laboratory-confirmed pneumococcal meningitis among Utah children from 1997 to 2010. We reviewed medical records and obtained clinical data during the acute illness and follow-up data on neurologic sequelae.

RESULTS:

Sixty-eight cases of meningitis were identified. PCV7 serotypes caused 64% of cases before and 25% of cases after licensure of PCV7 (P < .01). The age range was similar before and after PCV7 licensure (P = .5). The overall case fatality rate was 13% and was similar among cases caused by PCV7 and non-PCV7 serotypes (P = .7). Children with PCV7 serotypes were more likely to require mechanical ventilation (68% vs 34%; P < .01). Of all survivors, 63% had neurologic sequelae, and the proportion was similar after infection with PCV7 or non-PCV7 serotypes (P = .1). More than one-half (54%) of all children who developed pneumococcal meningitis in the PCV7 period were eligible for PCV7 and had not been immunized.

CONCLUSIONS:

Pneumococcal meningitis continues to be associated with high mortality and morbidity; death and neurologic sequelae are common with both PCV7 and non-PCV7 serotype meningitis. The substantial burden of this disease and continued cases among unimmunized children reinforce the need for more effective immunization strategies and continued surveillance in the era of PCV13.
Interventions to Modify Health Care Provider Adherence to Asthma Guidelines: A Systematic Review
Authors: Okelo Sande O. , Butz Arlene M. , Sharma Ritu , Diette Gregory B. , Pitts Samantha I. , King Tracy M. , Linn Shauna T. , Reuben Manisha , Chelladurai Yohalakshmi , Robinson Karen A.
Published: August 2013

BACKGROUND AND OBJECTIVE:

Health care provider adherence to asthma guidelines is poor. The objective of this study was to assess the effect of interventions to improve health care providers’ adherence to asthma guidelines on health care process and clinical outcomes.

METHODS:

Data sources included Medline, Embase, Cochrane CENTRAL Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, Educational Resources Information Center, PsycINFO, and Research and Development Resource Base in Continuing Medical Education up to July 2012. Paired investigators independently assessed study eligibility. Investigators abstracted data sequentially and independently graded the evidence.

RESULTS:

Sixty-eight eligible studies were classified by intervention: decision support, organizational change, feedback and audit, clinical pharmacy support, education only, quality improvement/pay-for-performance, multicomponent, and information only. Half were randomized trials (n = 35). There was moderate evidence for increased prescriptions of controller medications for decision support, feedback and audit, and clinical pharmacy support and low-grade evidence for organizational change and multicomponent interventions. Moderate evidence supports the use of decision support and clinical pharmacy interventions to increase provision of patient self-education/asthma action plans. Moderate evidence supports use of decision support tools to reduce emergency department visits, and low-grade evidence suggests there is no benefit for this outcome with organizational change, education only, and quality improvement/pay-for-performance.

CONCLUSIONS:

Decision support tools, feedback and audit, and clinical pharmacy support were most likely to improve provider adherence to asthma guidelines, as measured through health care process outcomes. There is a need to evaluate health care provider-targeted interventions with standardized outcomes.
The Transfer of Drugs and Therapeutics Into Human Breast Milk: An Update on Selected Topics
Authors: Sachs Hari Cheryl ,   COMMITTEE ON DRUGS, Frattarelli Daniel A. C. , Galinkin Jeffrey L. , Green Thomas P. , Johnson Timothy , Neville Kathleen , Paul Ian M. , Van den Anker John
Published: August 2013

Many mothers are inappropriately advised to discontinue breastfeeding or avoid taking essential medications because of fears of adverse effects on their infants. This cautious approach may be unnecessary in many cases, because only a small proportion of medications are contraindicated in breastfeeding mothers or associated with adverse effects on their infants. Information to inform physicians about the extent of excretion for a particular drug into human milk is needed but may not be available. Previous statements on this topic from the American Academy of Pediatrics provided physicians with data concerning the known excretion of specific medications into breast milk. More current and comprehensive information is now available on the Internet, as well as an application for mobile devices, at LactMed (http://toxnet.nlm.nih.gov). Therefore, with the exception of radioactive compounds requiring temporary cessation of breastfeeding, the reader will be referred to LactMed to obtain the most current data on an individual medication. This report discusses several topics of interest surrounding lactation, such as the use of psychotropic therapies, drugs to treat substance abuse, narcotics, galactagogues, and herbal products, as well as immunization of breastfeeding women. A discussion regarding the global implications of maternal medications and lactation in the developing world is beyond the scope of this report. The World Health Organization offers several programs and resources that address the importance of breastfeeding (see http://www.who.int/topics/breastfeeding/en/).
Primary Care Interventions to Prevent Tobacco Use in Children and Adolescents: U.S. Preventive Services Task Force Recommendation Statement
Authors: Moyer Virginia A.
Published: August 2013

Description:

Update of the 2003 U.S. Preventive Services Task Force (USPSTF) recommendation on primary care interventions to prevent tobacco use in children and adolescents.

Methods:

The USPSTF reviewed the evidence on the effectiveness of primary care interventions on the rates of initiation or cessation of tobacco use in children and adolescents and on health outcomes, such as respiratory health, dental and oral health, and adult smoking. The USPSTF also reviewed the evidence on the potential harms of these interventions.

Population:

This recommendation applies to school-aged children and adolescents. The USPSTF has issued a separate recommendation statement on tobacco use counseling in adults and pregnant women.

Recommendation:

The USPSTF recommends that primary care clinicians provide interventions, including education or brief counseling, to prevent initiation of tobacco use in school-aged children and adolescents.
Molecular Dynamics Study of Cu Thin Film Deposition onβ-Ta
Authors: Klaver Peter , Thijsse Barend J.
Published: August 2013

Molecular Dynamics simulations were performed to study Cu film deposition on β-Ta. Three different β-Ta surfaces were used, two being atomically flat, and one resulting from Ta on Ta growth. We find that the Cu films develop a (111) texture with vertical grain boundaries between grains having different epitaxial relations with the β-Ta substrate. The epitaxial rotation angles were determined, as 5.2° and 10-13°, and the resulting strain reductions in the Cu films were identified. The effects of the substrate differences on the interfacial Ta/Cu intermixing and the epitaxy and grain boundary structure of the films are discussed.
Job satisfaction among dental assistants in Brazil
Authors: Loretto Nelson Rubens Mendes , Caldas Jr Arnaldo de França , Coelho Junior Luiz Gutenberg Toledo de Miranda
Published: August 2013

The aim of the present study was to investigate the expressed levels of job satisfaction of dental assistants working in Brazil and whether there are relationships among professional formation standards, workplace relations and job satisfaction. An analytical cross-sectional study was carried out with a calculated sample of 443 dental assistants. A questionnaire was developed for this purpose and its validity was verified in a pilot study. The questionnaire provided data for socioeconomic and demographic categorization and identified the variables that could be correlated to professional satisfaction. Job satisfaction was stratified into satisfaction and no satisfaction. All participants signed an informed consent form. Data were analyzed using SPSS software, version 13.0. Pearson's chi-square and Fisher's exact tests were performed. Among the 443 participants, 94.6% were women, 72.7% were aged between 21 and 40 years and 65.0% were single. Over half had 37 or more months of job experience and had completed their course at a public institution. The majority earned between US$141.00 and US$190.00 per month. Job satisfaction was mentioned by 81.5% of the dental personnel. It was found that most subjects were satisfied with their job, and that the level satisfaction is influenced negatively by salary, workplace, workload and dentist's personality.
Ex-vivo Effect of Intracanal Medications Based on Ozone and Calcium Hydroxide in Root Canals Contaminated with Enterococcus faecalis
Authors: Farac Roberta Vieira , Pizzolitto Antonio Carlos , Tanomaru Juliane Maria Guerreiro , Morgental Renata Dornelles , Lima Regina Karla de Pontes , Bonetti-Filho Idomeo
Published: August 2013

This ex vivo study evaluated the antibacterial effect of intracanal medications in root canals contaminated with Enterococcus faecalis. Fifty single-rooted human teeth were contaminated with E. faecalis (ATCC 29212) and incubated at 37°C for 21 days. The specimens were randomly divided into 5 groups according to the intracanal medication used: OZ-PG: ozonized propylene glycol; CH/CPMC: calcium hydroxide/camphorated paramonochlorophenol; OZ-PG/CH ozonized PG/CH; PC: positive control group (no medication); and NC: negative control group (no contamination). The samples were collected after 7 days (post-medication) and 14 days (final). Bacterial growth was checked by counting the colony-forming units (CFU). OZ-PG and CH/CPMC reduced significantly the CFU counts compared with PC in the post-medication and final samples, with no statistically significant differences among them. On the other hand, OZ-PG/CH did not reduce significantly the number of bacteria compared with PC. In conclusion, among the evaluated medications OZ-PG and CH/CPMC were the most effective against E. faecalis.
History of Chronic Periodontitis Is a High Risk Indicator for Peri-Implant Disease
Authors: Casado Priscila Ladeira , Pereira Marcelo Constante , Duarte Maria Eugenia Leite , Granjeiro José Mauro
Published: August 2013

The success rates in implant dentistry vary significantly among patients presenting previous history of periodontitis. The aim of this study was to evaluate if patients with history of chronic periodontitis (CP) are more susceptible to peri-implant disease (PID) than those without history of CP. Two hundred and fifteen individuals, under periodontal maintenance, presenting 754 osseointegrated implants, were selected for this study. The patients were divided into two groups according to the peri-implant status: Control group (patients without PID; n=129) and PID group (patients with PID; n=86). All peri-implant regions were clinically evaluated, including analyses of mucosa inflammation, edema and implant mobility. Periapical radiography assessed the presence of peri-implant bone loss. According to the clinical/radiographic characteristics, patients in Control and PID groups were diagnosed as having CP or not. Nominal variables were evaluated by the chi-square test. The distribution of numeric variables was analyzed by Shapiro-Wilk test. Student's t-test and Mann-Whitney test were used to analyze significant differences for parametric and non-parametric data. A p-value <0.05 was considered significant. There was a highly significant correlation between CP history and PID (p<0.0001). Patients with CP had 4 times more chance of developing PID than patients with healthy periodontal tissues. Also, CP patients showed higher bleeding on probing (p=0.002) and bone loss around implant (p=0.004) when compared with patients without CP. In conclusion, history of CP is a high risk factor for the development of PID, irrespective of gender or region of implant placement.
Cytotoxicity of root canal sealers on endothelial cell cultures
Authors: Martins Vagner José Medeiros , Lins Renata Ximenes , Berlinck Teresa Cristina Ávila , Fidel Rivail Antônio Sérgio
Published: August 2013

This study evaluated, in vitro, the cytotoxicity of six root canal sealers after 12, 24 and 72 h of contact time, using an endothelial ECV-304 cell line. The MTT assay was used for analysis of cell viability. Twelve specimens of each sealer were prepared and randomly assigned to 6 groups according to the commercial brands (n=4/time). A control group was also formed, which was not subjected to the contact with sealers. To assess the effects of sealers on endothelial cells, the specimens were placed in culture plate wells and incubated at 37°C with 5% CO2 and 100% humidity. MTT assays were performed in quadruplicate after 12, 24 and 72 h of contact of the sealer specimens with monolayers. Statistical analysis was performed by two-way ANOVA with Bonferroni post-hoc test at a significance level of 5%. Analysis of absorbance in the experimental groups showed that GuttaFlow presented the lowest cytotoxicity, with a mean absorbance of 0.048, followed by Pulp Canal Sealer (0.038), Sealer 26 (0.038), Endo Densell (0.036) and Pulp Fill (0.035). The control group had a mean absorbance of 0.098. Based on the results, Endofill and GuttaFlow were the most and the least cytotoxic sealers, respectively.
Lingual Cortical Mandibular Bone Depression: Frequency and Clinical-Radiological Features in a Brazilian Population
Authors: Mourão Carlos Fernando de Almeida Barros , Miranda Águida Maria Menezes Aguiar , Santos Eduardo José da Costa , Pires Fábio Ramôa
Published: August 2013

The aim of this study was to report the frequency and clinical-radiological features of cases of lingual cortical mandibular bone depressions (LCMBD) diagnosed in consecutive panoramic radiographs and cone-beam computed tomography (CBCT) scans from a Brazilian population. The methods included a retrospective analysis of consecutive panoramic radiographs, charts from the Oral Medicine clinic and consecutive CBCT scans. All cases diagnosed as LCMBD were selected and clinical-radiological data were retrieved from the clinical charts and by the analysis of the image exams. Twenty LCMBD cases diagnosed in 18 patients were found, including 2 from 3,000 consecutive panoramic radiographs (0.07%), 6 from 2,421 Oral Medicine patients (0.25%) and 10 from 1,684 CBCT scans (0.59%). The 18 patients had a mean age of 51.5 years and 13 were males. Two patients presented bilateral lesions. Fourteen images (70%) were classified as well-defined. Eighteen affected the posterior area of the mandible and two affected the anterior mandible. Size of the lesions was larger in younger patients. In conclusion, there seemed to be a considerable radiological heterogeneity when comparing the LCMBD cases and it seemed that the images decreased in size with the increase of patient's age.
Stress Distribution in Co-Cr Implant Frameworks after Laser or TIG Welding
Authors: Castro Gabriela Cassaro de , Araújo Cleudmar Amaral de , Mesquita Marcelo Ferraz , Consani Rafael Leonardo Xediek , Nóbilo Mauro Antônio de Arruda
Published: August 2013

Lack of passivity has been associated with biomechanical problems in implant-supported prosthesis. The aim of this study was to evaluate the passivity of three techniques to fabricate an implant framework from a Co-Cr alloy by photoelasticity. The model was obtained from a steel die simulating an edentulous mandible with 4 external hexagon analog implants with a standard platform. On this model, five frameworks were fabricated for each group: a monoblock framework (control), laser and TIG welding frameworks. The photoelastic model was made from a flexible epoxy resin. On the photoelastic analysis, the frameworks were bolted onto the model for the verification of maximum shear stress at 34 selected points around the implants and 5 points in the middle of the model. The stresses were compared all over the photoelastic model, between the right, left, and center regions and between the cervical and apical regions. The values were subjected to two-way ANOVA, and Tukey's test (α=0.05). There was no significant difference among the groups and studied areas (p>0.05). It was concluded that the stresses generated around the implants were similar for all techniques.
Multidisciplinary Therapy of Extensive Oligodontia: A Case Report
Authors: Gonçalves Thaís Marques Simek Vega , Gonçalves Letícia Machado , Sabino-Bezerra José Ribamar , Santos-Silva Alan Roger , Silva Wander José da , Garcia Renata Cunha Matheus Rodrigues
Published: August 2013

Oligodontia is a rare congenital disorder consisting in the absence of six or more teeth. This case report describes a multidisciplinary treatment approach for a 12-year-old male with absence of 11 permanent teeth. Prior to any procedure, all primary teeth were scheduled for extraction due to poor crown-to-root ratio. The treatment plan comprised two phases: 1. orthodontic and speech therapy aimed at overbite and anterior open bite adjustment, as well as tongue position improvement; and 2. prosthetic treatment by insertion of removable temporary partial dentures. The multidisciplinary treatment involving orthodontics, speech and prosthetic therapies have reestablished the masticatory function and aesthetics, allowing the patient to achieve greater self-esteem and better social acceptance.