“The Ultimate Decision Is Yours”: Exploring Patients’ Attitudes about the Overuse of Medical Interventions

Previous research has found that American patients strongly believe that more testing and more treatment lead to better outcomes and, to a lesser extent, that newer treatments are more effective. We conducted five focus groups with privately insured, healthy, middle-aged Americans (n = 43) to explore these apparent preferences. Contrary to previous research, an unexpected distinction emerged. Participants placed enormous value on testing and screening, reacting with hostility to guidelines recommending less of either. However, they were suspicious of overmedication. The wariness of pharmaceuticals and enthusiasm for testing and screening both appear to reflect participants’ efforts to take responsibility for their health. But recommendations to test and screen less conflicted with their active, engaged, information-seeking roles. Nonetheless, given patients’ concerns about overuse of pharmaceuticals, we maintain that they can learn to understand the connections between over-testing and over-treatment, and can actively choose to do less. We close with suggestions about how treatment guidelines can better communicate these connections to patients. Our findings cannot necessarily be generalized beyond privately-insured, healthy, middle-aged Americans. But because we found that, among these individuals, attitudes towards pharmaceuticals differ from attitudes towards testing and screening, we maintain that future research should also distinguish among and compare attitudes towards different types of medical interventions.     

Reversibility and "pH-T phase diagrams" of Rapana venosa hemocyanin and its structural subunits

We have studied the stability and reassociation behaviour of native molecules of Rapana venosa hemocyanin and its two subunits, termed RvH1 and RvH2. In the presence of different concentrations of Ca(2+) and Mg(2+) ions and pH values, the subunits differ not only in their reassociation behaviour, but also in their formation of helical tubules and multidecamers. RvH1 revealed a greater stability at higher pH values compared to RvH2. Overall, the stability of reassociated RvH and its structural subunits was found to be pH-dependent. The increasing stability of native Hc and its subunits, shown by pH-induced CD transitions (acid and alkaline denaturation), can be explained with the formation of quaternary structure. The absence of a Cotton effect at temperatures 20-40 degrees C in the pH-transition curves of RvH2 indicates that this subunit is stabilized by additional "factors", e.g.: non-ionic/hydrophobic stabilization and interactions of carbohydrate moieties. A similar behaviour was observed for the T-transition curves in a wide pH interval for RvH and its structural subunits. At higher temperatures, many of the secondary structural elements are preserved especially at neutral pH, even at extreme high temperatures above 90 degrees C the protein structures resemble a "globule state".     

Novel bacterial endosymbionts of Acanthamoeba spp. related to the Paramecium caudatum symbiont Caedibacter caryophilus

Acanthamoebae are increasingly being recognized as hosts for obligate bacterial endosymbionts, most of which are presently uncharacterized. In this study, the phylogeny of three Gram-negative, rod-shaped endosymbionts and their Acanthamoeba host cells was analysed by the rRNA approach. Comparative analyses of 16S rDNA sequences retrieved from amoebic cell lysates revealed that the endosymbionts of Acanthamoeba polyphaga HN-3, Acanthamoeba sp. UWC9 and Acanthamoeba sp. UWE39 are related to the Paramecium caudatum endosymbionts Caedibacter caryophilus, Holospora elegans a n d Holospora obtusa . With overall 16S rRNA sequence similarities to their closest relative, C. caryophilus , of between 87% and 93%, these endosymbionts represent three distinct new species. In situ hybridization with fluorescently labelled endosymbiont-specific 16S rRNA-targeted probes demonstrated that the retrieved 16S rDNA sequences originated from the endosymbionts and confirmed their intracellular localization. We propose to classify provisionally the endosymbiont of Acanthamoeba polyphaga HN-3 as ' Candidatus Caedibacter acanthamoebae', the endosymbiont of Acanthamoeba sp. strain UWC9 as ' Candidatus Paracaedibacter acanthamoebae' and the endosymbiont of Acanthamoeba sp. strain UWE39 as ' Candidatus Paracaedibacter symbiosus'. The phylogeny of the Acanthamoeba host cells was analysed by comparative sequence analyses of their 18S rRNA. Although Acanthamoeba polyphaga HN-3 clearly groups together with most of the known Acanthamoeba isolates (18S rRNA sequence type 4), Acanthamoeba sp. UWC9 and UWE39 exhibit < 92% 18S rRNA sequence similarity to each other and to other Acanthamoeba isolates. Therefore, we propose two new sequence types (T13 and T14) within the genus Acanthamoeba containing, respectively, Acanthamoeba sp. UWC9 and Acanthamoeba sp. UWE39.     

A reference-quality,fully annotated genome from a Puerto Rican individual

Until 2019, the human genome was available in only one fully annotated version, GRCh38, which was the result of 18 years of continuous improvement and revision. Despite dramatic improvements in sequencing technology, no other genome was available as an annotated reference until 2019, when the genome of an Ashkenazi individual, Ash1, was released. In this study, we describe the assembly and annotation of a second individual genome, from a Puerto Rican individual whose DNA was collected as part of the Human Pangenome project. The new genome, called PR1, is the first true reference genome created from an individual of African descent. Due to recent improvements in both sequencing and assembly technology, and particularly to the use of the recently completed CHM13 human genome as a guide to assembly, PR1 is more complete and more contiguous than either GRCh38 or Ash1. Annotation revealed 37,755 genes (of which 19,999 are protein coding), including 12 additional gene copies that are present in PR1 and missing from CHM13. Fifty-seven genes have fewer copies in PR1 than in CHM13, 9 map only partially, and 3 genes (all noncoding) from CHM13 are entirely missing from PR1.     

Real-time Investigation of SV40 Large T-antigen Helicase Activity Using Surface Plasmon Resonance

The simian virus 40 (SV40) genome is a model system frequently employed for investigating eukaryotic replication. Large T-antigen (T-ag) is a viral protein responsible for unwinding the SV40 genome and recruiting necessary host factors prior to replication. In addition to duplex unwinding T-ag possesses G-quadruplex DNA helicase activity, the physiological consequence of which is unclear. However, formation of G-quadruplex DNA structures may be involved in genome maintenance and function, and helicase activity to resolve these structures may be necessary for efficient replication. We report the first real-time investigation of SV40 T-ag helicase activity using surface plasmon resonance (SPR). In the presence of ATP, T-ag was observed to bind to immobilized single-stranded DNA, forked duplex DNA, and the human telomeric foldover quadruplex DNA sequence. Inhibition of T-ag duplex helicase activity was observable in real-time and the intramolecular quadruplex was unwound.

Silintaphin-1--interaction with silicatein during structure-guiding bio-silica formation

Silicateins are unique enzymes of sponges (phylum Porifera) that template and catalyze the polymerization of nanoscale silicate to siliceous skeletal elements. These multifunctional spicules are often elaborately shaped, with complex symmetries. They carry an axial proteinaceous filament, consisting of silicatein and the scaffold protein silintaphin-1, which guides silica deposition and subsequent spicular morphogenesis. In vivo, the synthesis of the axial filament very likely proceeds in three steps: (a) assembly of silicatein monomers to form one pentamer; (b) assembly of pentamers to form fractal-like structures; and finally (c) assembly of fractal-like structures to form filaments. The present study was aimed at exploring the effect of self-assembled complexes of silicatein and silintaphin-1 on biosilica synthesis in vitro. Hence, in a comparative approach, recombinant silicatein and recombinant silintaphin-1 were used at different stoichiometric ratios to form axial filaments and to synthesize biosilica. Whereas recombinant silicatein-α reaggregates to randomly organized structures, coincubation of silicatein-α and silintaphin-1 (molecular ratio 4 : 1) resulted in synthetic filaments via fractal-like patterned self-assemblies, as observed by electron microscopy. Concurrently, owing to the concerted action of both proteins, the enzymatic activity of silicatein-α strongly increased by 5.3-fold (with the substrate tetraethyl orthosilicate), leading to significantly enhanced synthesis of biosilica. These results indicate that silicatein-α-mediated biosilicification depends on the concomitant presence of silicatein-α and silintaphin-1. Accordingly, silintaphin-1 might not only enhance the enzymatic activity of silicatein-α, but also accelerate the nonenzymatic polycondensation of the silica product before releasing the fully synthesized biosiliceous polymer.