On Minimum Spanning Subgraphs of Graphs With Proper Connection Number 2

An edge coloring of a connected graph G is a proper-path coloring if every two vertices of G are connected by a properly colored path. The minimum number of colors required of a proper-path coloring of G is called the proper connection number pc(G) of G. For a connected graph G with proper connection number 2, the minimum size of a connected spanning subgraph H of G with pc(H) = 2 is denoted by μ(G). It is shown that if s and t are integers such that t ≥ s + 2 ≥ 5, then μ(K_{s,t} ) = 2t − 2. We also determine μ(G) for several classes of complete multipartite graphs G. In particular, it is shown that if G = K_{n_1, n_2, ..., n_k} is a complete k-partite graph, where k ≥ 3, r = \sum^{k−1}_{i=1} n_i ≥ 3 and t = n_k ≥ r^2 + r, then μ(G) = 2t − 2r + 2

Geologic Characterization, Hydrologic Monitoring, and Soil-Water Relationships for Landslides in Kentucky

Complex spatial and temporal variables control the movement of water through colluvial soils in hillslopes. Some of the factors that influence soil-moisture fluctuation are soil type, thickness, porosity and permeability, and slope morphology. Landslide-characterization and field-monitoring techniques were part of a method to connect hydrologic and geotechnical data in order to monitor long-term hydrologic conditions in three active landslides in Kentucky, establish hydrologic relationships across the slope, and analyze specific soil-water relationships that can predict shear strength. Volumetric water content, water potential, and electrical conductivity were measured between October 2015 and February 2019. The duration and magnitude of drying and wetting within the soil varied for each slope location and soil depth, suggesting that differences in slope morphology, soil texture, and porosity influence the water-infiltration process, as well as shear strength and general landslide dynamics. The parameters measured and soil-water relationships were also compared to rainfall and slope movement at one of the landslides. The method used to acquire hydrologic data was cost-effective, and the field techniques may be useful for subsequent projects, such as slope-stability assessments and landslide-susceptibility modeling. Hydrologic parameters, volumetric water content, and water potential are pertinent to investigating the stability of landslides, which are often triggered or reactivated by rainfall. These methods can be used to support landslide-hazard assessment and improve our understanding of the long-term influence of moisture conditions in hillslope soils

Dynamic Site Periods for the Jackson Purchase Region of Western Kentucky

Bridges, overpasses, and other engineered structures in the Jackson Purchase region of Western Kentucky are, of necessity, built on a thick column of loose to semi-consolidated sediments. Because these sediments tend to amplify seismically induced ground motions at preferred periods, structures with natural periods close to the preferred periods of amplification of the ground motions are particularly vulnerable to damages during an earthquake because of in-phase resonance. For this report, conventional seismic refraction and reflection techniques were used to determine the shearwave velocities of the more poorly consolidated, near-surface sediments for a matrix of sites in the region. Conventional seismic P-wave reflections along with existing drill hole and seismic reflection data in the region were then used to determine the depth to the top of the bedrock at the sites investigated. These data were used in SHAKE91 to calculate the fundamental period of the ground motion at the sites. This period, identified in the study as the dynamic site period, is the period at which ground motions in the sedimentary column are most apt to be amplified as a result of a seismic shear wave propagating from the top of the bedrock to the surface. Based on the results in this report, it is recommended that bridges, overpasses, and other engineered structures built in the region be designed so that their natural periods do not coincide with the fundamental period of the sedimentary column, thereby avoiding damage during an earthquake as a result of in-phase resonance

Application of a synthetic human proteome to autoantigen discovery through PhIP-Seq

In this study, we improve on current autoantigen discovery approaches by creating a synthetic representation of the complete human proteome, the T7 “peptidome” phage display library (T7-Pep), and use it to profile the autoantibody repertoires of individual patients. We provide methods for 1) designing and cloning large libraries of DNA microarray-derived oligonucleotides encoding peptides for display on bacteriophage, and 2) analysis of the peptide libraries using high throughput DNA sequencing. We applied phage immunoprecipitation sequencing (PhIP-Seq) to identify both known and novel autoantibodies contained in the spinal fluid of three patients with paraneoplastic neurological syndromes. We also show how our approach can be used more generally to identify peptide-protein interactions and point toward ways in which this technology will be further developed in the future. We envision that PhIP-Seq can become an important new tool in autoantibody analysis, as well as proteomic research in general

A Multicenter, Phase 2 Study of Vascular Endothelial Growth Factor Trap (Aflibercept) in Platinum- and Erlotinib-Resistant Adenocarcinoma of the Lung

IntroductionAflibercept (vascular endothelial growth factor [VEGF] trap), a recombinant fusion protein, blocks the activity of VEGF-A and placental growth factor and has demonstrated activity in pretreated patients with lung cancer in a phase I trial. This study evaluated the efficacy and safety of intravenous aflibercept in patients with platinum- and erlotinib-resistant lung adenocarcinoma.MethodsAn open-label, single arm, multicenter trial was conducted, with the primary end point of response rate (modified RECIST). Additional endpoints included safety, duration of response, progression-free survival, and overall survival. Patients with platinum- and erlotinib-resistant lung adenocarcinoma were eligible. Aflibercept 4.0 mg/kg intravenous every 2 weeks was administered until progression of disease or intolerable toxicity.ResultsNinety-eight patients were enrolled; 89 were evaluable for response. Median age was 60 years, 41% were men with Eastern Cooperative Oncology Group performance status 0/1/2 in 35/55/9% of patients. The overall response rate was 2.0%, (95% confidence interval, 0.2-7.2%). Median progression-free survival was 2.7 months, and overall was survival 6.2 months. Six- and 12-month survival rates were 54 and 29%, respectively. A median of four cycles was administered (range 1-22). Common grade 3/4 toxicities included dyspnea (21%), hypertension (23%), and proteinuria (10%). Two cases of grade 5 hemoptysis were reported, and one case each of tracheoesophageal fistula, decreased cardiac ejection fraction, cerebral ischemia, and reversible posterior leukoencephalopathy.ConclusionsAflibercept has minor single agent activity in heavily pretreated lung adenocarcinoma, and is well tolerated, with no unexpected toxicities. Further studies evaluating aflibercept in lung cancer, in combination with chemotherapy and other targeted therapies, are ongoing

PolyQ Repeat Expansions in ATXN2 Associated with ALS Are CAA Interrupted Repeats

Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressive disease leading to paralysis and death. Recently, intermediate length polyglutamine (polyQ) repeats of 27–33 in ATAXIN-2 (ATXN2), encoding the ATXN2 protein, were found to increase risk for ALS. In ATXN2, polyQ expansions of ≥34, which are pure CAG repeat expansions, cause spinocerebellar ataxia type 2. However, similar length expansions that are interrupted with other codons, can present atypically with parkinsonism, suggesting that configuration of the repeat sequence plays an important role in disease manifestation in ATXN2 polyQ expansion diseases. Here we determined whether the expansions in ATXN2 associated with ALS were pure or interrupted CAG repeats, and defined single nucleotide polymorphisms (SNPs) rs695871 and rs695872 in exon 1 of the gene, to assess haplotype association. We found that the expanded repeat alleles of 40 ALS patients and 9 long-repeat length controls were all interrupted, bearing 1–3 CAA codons within the CAG repeat. 21/21 expanded ALS chromosomes with 3CAA interruptions arose from one haplotype (GT), while 18/19 expanded ALS chromosomes with <3CAA interruptions arose from a different haplotype (CC). Moreover, age of disease onset was significantly earlier in patients bearing 3 interruptions vs fewer, and was distinct between haplotypes. These results indicate that CAG repeat expansions in ATXN2 associated with ALS are uniformly interrupted repeats and that the nature of the repeat sequence and haplotype, as well as length of polyQ repeat, may play a role in the neurological effect conferred by expansions in ATXN2

Regulation of Hepatocyte Nuclear Factor 1 Activity by Wild-Type and Mutant Hepatitis B Virus X Proteins

The hepatitis B virus (HBV) core promoter regulates the transcription of two related RNA products named precore RNA and core RNA. Previous studies indicate that a double-nucleotide mutation that occurs frequently during chronic HBV infection converts a nuclear receptor binding site in the core promoter to the binding site of the transcription factor hepatocyte nuclear factor-1 (HNF-1) and specifically suppresses the transcription of the precore RNA. This mutation also changes two codons in the overlapping X protein coding sequence. In this report, we demonstrate that the X protein and its mutant X(mt) can physically bind to HNF-1 both in vitro and in vivo. Further analyses indicate that both X and X(mt) can enhance the gene transactivation and the DNA binding activities of HNF-1. This finding demonstrates for the first time that the X protein can stimulate the DNA binding activity of a homeodomain transcription factor. Interestingly, while both X and X(mt) can stimulate the HNF-1 activities, they differ in their effects: a smaller amount of X(mt) is needed to generate greater transactivation and DNA binding activities of HNF-1. This functional difference between X and X(mt) may have important implications in HBV pathogenesis and is apparently why they have different effects on the core promoter bearing the HNF-1 binding site

Identification of Streptococcus sanguinis Genes Required for Biofilm Formation and Examination of Their Role in Endocarditis Virulence

Streptococcus sanguinisis one of the pioneers in the bacterial colonization of teeth and is one of the most abundant species in the oral biofilm called dental plaque.S. sanguinisis also the most common viridans group streptococcal species implicated in infective endocarditis. To investigate the association of biofilm and endocarditis, we established a biofilm assay and examined biofilm formation with a signature-tagged mutagenesis library ofS. sanguinis. Four genes that have not previously been associated with biofilm formation in any other bacterium,purB, purL, thrB, andpyrE, were putatively identified as contributing to in vitro biofilm formation inS. sanguinis. By examining 800 mutants for attenuation in the rabbit endocarditis model and for reduction in biofilm formation in vitro, we found some mutants that were both biofilm defective and attenuated for endocarditis. However, we also identified mutants with only reduced biofilm formation or with only attenuation in the endocarditis model. This result indicates that the ability to form biofilms in vitro is not associated with endocarditis virulence in vivo inS. sanguinis

B cell TLR1/2, TLR4, TLR7 and TLR9 interact in induction of class switch DNA recombination: Modulation by BCR and CD40, and relevance to T-independent antibody responses

Ig class switch DNA recombination (CSR) in B cells is crucial to the maturation of antibody responses. It requires IgH germline IH-CH transcription and expression of AID, both of which are induced by engagement of CD40 or dual engagement of a Toll-like receptor (TLR) and B cell receptor (BCR). Here, we have addressed cross-regulation between two different TLRs or between a TLR and CD40 in CSR induction by using a B cell stimulation system involving lipopolysaccharides (LPS). LPS-mediated long-term primary class-switched antibody responses and memory-like antibody responses in vivo and induced generation of class-switched B cells and plasma cells in vitro. Consistent with the requirement for dual TLR and BCR engagement in CSR induction, LPS, which engages TLR4 through its lipid A moiety, triggered cytosolic Ca2+ flux in B cells through its BCR-engaging polysaccharidic moiety. In the presence of BCR crosslinking, LPS synergized with a TLR1/2 ligand (Pam3CSK4) in CSR induction, but much less efficiently with a TLR7 (R-848) or TLR9 (CpG) ligand. In the absence of BCR crosslinking, R-848 and CpG, which per se induced marginal CSR, virtually abrogated CSR to IgG1, IgG2a, IgG2b, IgG3 and/or IgA, as induced by LPS or CD154 (CD40 ligand) plus IL-4, IFN-γ or TGF-β, and reduced secretion of class-switched Igs, without affecting B cell proliferation or IgM expression. The CSR inhibition by TLR9 was associated with the reduction in AID expression and/or IgH germline IH-S-CH transcription, and required co-stimulation of B cells by CpG with LPS or CD154. Unexpectedly, B cells also failed to undergo CSR or plasma cell differentiation when co-stimulated by LPS and CD154. Overall, by addressing the interaction of TLR1/2, TLR4, TLR7 and TLR9 in the induction of CSR and modulation of TLR-dependent CSR by BCR and CD40, our study suggests the complexity of how different stimuli cross-regulate an important B cell differentiation process and an important role of TLRs in inducing effective T-independent antibody responses to microbial pathogens, allergens and vaccines