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Objective Early diagnosis of atrial fibrillation (AFib) is a priority for stroke prevention. We sought to test four commercial pulse detection systems (CPDSs) for ability to distinguish AFib from normal sinus rhythm using a published algorithm (Zhou et al., PLoS One 2015;10:e0136544), compared with visual diagnosis by electrocardiogram inspection. Methods BAYathlon was a prospective, non-interventional, single-centre study. Adult cardiology patients with documented AFib or sinus rhythm who were due to have a routine 5-min electrocardiogram were randomized to undergo a parallel 5-min pulse assessment with a Polar V800, eMotion Faros 360, TomTom heart rate monitor, or Adidas miCoach Smart Run. Results 144 patients (73 with AFib, 71 with sinus rhythm (based on electrocardiograms); median age: 73 years; 53.5% male) were analysed. Algorithm sensitivities (primary endpoint) and specificities for AFib when applied to CPDS recordings were 93.3% and 94.1% with the Polar V800, 90.0% and 84.2% with the eMotion Faros 360, and 0% and 100% with the other CPDSs (analysis period: 127 heart rate signals + 2 min). When applied to routine electrocardiograms, the algorithm correctly detected AFib in 71/73 patients. Different analysis periods (127 heart rate signals +1 or 3 min) only slightly changed the sensitivities with the Polar V800 and eMotion Faros 360 and had no effect on the sensitivities with the other CPDSs. Conclusion AFib screening using the applied algorithm is feasible with the Polar V800 and eMotion Faros 360 (which provide RR interval data) but not with the other CPDSs (which provide pre-processed heart rate time series). ClinicalTrials.gov identifier: NCT02875106

Most-probable-number (liquid serial dilution culture) counts were obtained for polysaccharolytic and saccharolytic fermenting bacteria in the anoxic bulk soil of flooded microcosms containing rice plants. The highest viable counts (up to 2.5 × 10 8 cells per g [dry weight] of soil) were obtained by using xylan, pectin, or a mixture of seven mono- and disaccharides as the growth substrate. The total cell count for the soil, as determined by using 4′,6-diamidino-2-phenylindole staining, was 4.8 × 10 8 cells per g (dry weight) of soil. The nine strains isolated from the terminal positive tubes in counting experiments which yielded culturable populations that were equivalent to about 5% or more of the total microscopic count population belonged to the division Verrucomicrobia , the Cytophaga-Flavobacterium-Bacteroides division, clostridial cluster XIVa, clostridial cluster IX, Bacillus spp., and the class Actinobacteria . Isolates originating from the terminal positive tubes of liquid dilution series can be expected to be representatives of species whose populations in the soil are large. None of the isolates had 16S rRNA gene sequences identical to 16S rRNA gene sequences of previously described species for which data are available. Eight of the nine strains isolated fermented sugars to acetate and propionate (and some also fermented sugars to succinate). The closest relatives of these strains (except for the two strains of actinobacteria) were as-yet-uncultivated bacteria detected in the same soil sample by cloning PCR-amplified 16S rRNA genes (U. Hengstmann, K.-J. Chin, P. H. Janssen, and W. Liesack, Appl. Environ. Microbiol. 65:5050–5058, 1999). Twelve other isolates, which originated from most-probable-number counting series indicating that the culturable populations were smaller, were less closely related to cloned 16S rRNA genes.

Rice paddy soils are one of the major sources of atmospheric methane (15). These flooded soils contain largely uncharacterized microbial populations which degrade polymeric organic matter to low-molecular-weight compounds, such as acetate, H2, and CO2. These compounds are finally converted to methane by methanogenic archaea (16). Several cultivation studies to characterize autochthonous bacterial inhabitants of rice paddy soils have been performed (18, 19, 34, 51). It is not clear how successful such studies have been in characterizing bacterial communities. It has been estimated, for example, that the portion of microbial diversity which has been obtained in pure culture by conventional cultivation techniques amounts to only 0.1 to 1% of the total diversity (1, 12). Similarly, attempts to cultivate the bacteria in soils typically yield culturable cell numbers that are less than 5% (usually less than 1%) of the total microscopically countable cell numbers (3, 29). These observations indicate the inadequacy of culture methods to characterize complex microbial communities. One reason for this inadequacy is that the growth conditions used for direct enrichment cultures (i.e., cultures grown with undiluted inoculum) often do not reflect the natural conditions in the environment examined and thus select for fast-growing bacteria which are best adapted to the growth medium (16, 29, 49, 50). Consequently, the microorganisms obtained in pure culture may not have numerical or ecological significance for the biogeochemical processes in the environment, and abundant or even dominant populations may not be detected. Underestimation of microbial diversity by culture methods has favored the use of cultivation-independent, molecular approaches to investigate the microbial diversity in natural environments. The studies which have been performed have focused mainly on retrieval and comparative analysis of 16S rRNA-encoding gene (rDNA) sequences. The results not only have dramatically changed our view of the evolution and phylogenetic diversity of prokaryotes but also have confirmed the immense underrepresentation of naturally occurring bacteria and archaea obtained so far in pure culture (4, 11, 17, 23, 24, 29, 32). It has, however, become clear that the cultivation-independent PCR-based 16S rDNA approach is also characterized by limitations and pitfalls (29). The steps used can lead to biases in the proportions of the 16S rDNA sequence types recovered. Consequently, this approach is more qualitative than quantitative. In addition, inferring an ecological role or even a defined phenotype on the basis of the phylogenetic position of an environmental 16S rDNA sequence is often not possible. In an attempt to address the problems mentioned above, we applied to the same sample of rice paddy soil a culture method in which we used serial liquid dilutions of inoculum and a technique to recover environmental 16S rDNA. Cultivation was carried out by using the anaerobic most-probable-number (MPN) counting format. Using this dual approach, a previous study was able to gain insight into the structural and functional composition of the methanogenic community in anoxic rice paddy soil (16). In the present study we focused on the bacterial community, which was probably more diverse. Isolation of 19 saccharolytic and cellulolytic bacteria obtained from terminal and subterminal positive dilution steps of the MPN counting procedure and phenotypic characterization of these bacteria are described in the accompanying paper (8). Below, these bacteria are referred to as MPN isolates. Here we describe the results of a comparative phylogenetic analysis of two different 16S rDNA data sets generated during this investigation; i.e., sequence data for the 19 MPN isolates were compared to 57 environmental 16S rDNA clone sequences. Close matches between the two data sets revealed that the isolates were representatives of predominant bacterial groups, and thus our findings resulted in a more objective view of the structural and functional composition of the bacterial community inhabiting the anoxic rice paddy soil which we studied.