Predictors of mortality of patients newly diagnosed with clinical type 2 diabetes: a 5-year follow up study

Background

At diabetes diagnosis major decisions about life-style changes and treatments are made based on characteristics measured shortly after diagnosis. The predictive value for mortality of these early characteristics is widely unknown. We examined the predictive value of patient characteristics measured shortly after diabetes diagnosis for 5-year all-cause and cardiovascular mortality with special reference to self-rated general health.

Methods

Data were from a population-based sample of 1,323 persons newly diagnosed with clinical diabetes and aged 40 years or over. Possible predictors of mortality were investigated in Cox regression models.

Results

Multivariately patients who rated their health less than excellent experienced increased all-cause and cardiovascular mortality. These end-points also increased with sedentary life-style, relatively young age at diagnosis and presence of cardiovascular disease (CVD) at diagnosis. Further predictors of all-cause mortality were male sex, low body mass index and cancer, while cardiovascular mortality increased with urinary albumin concentration.

Conclusions

We found that patients who rated their health as less than excellent had increased 5-year mortality, similar to that of patients with prevalent CVD, even when biochemical, clinical and life-style variables were controlled for. This finding could motivate doctors to discuss perceptions of health with newly diagnosed diabetic patients and be attentive to patients with suboptimal health ratings. Our findings also confirm that life-style changes and optimizing treatment are particularly relevant for relatively young and inactive patients and those who already have CVD or (micro)albuminuria at the time of diabetes diagnosis.     

An interstate highway affects gene flow in a top reptilian predator (<Emphasis Type="Italic">Crotalus atrox</Emphasis>) of the Sonoran Desert

Roads can substantially impact the population connectivity of a wide range of terrestrial vertebrates, often resulting in loss of genetic diversity and an increase of spatial genetic structure. We studied the Western Diamond-backed Rattlesnake (Crotalus atrox), a large and abundant venomous predator, to test the hypothesis that a large and relatively new roadway in Arizona (Interstate Highway I-10) is a barrier that impacts gene flow and population genetics via habitat fragmentation. Based on 72 C. atrox sampled from three specific sampling sites (“subpopulations”) on both the west and east corridors of I-10, we used 30 nuclear microsatellite DNA loci and three mitochondrial DNA genes (2615 bp) to assess genetic diversity and structure, estimate effective population size (N _e ), and describe patterns of gene flow. We found no evidence for loss of genetic diversity or a decrease in N _e between the three subpopulations. Our microsatellite analysis showed that two subpopulations in close proximity (4 km), but separated by I-10, showed greater levels of genetic differentiation than two subpopulations that were separated by a greater distance (7 km) and not by I-10 or any other obvious barriers. Mitochondrial DNA analyses showed no significant genetic differentiation nor any indication of historically impeded gene flow. Tajima’s D and mismatch distribution tests revealed that demographic expansion is occurring in the overall population (all three subpopulations). Bayesian clustering and spatial genetic autocorrelation analyses of microsatellite data showed resistance to gene flow at the approximate location of I-10. Simulations that investigated gene flow between the subpopulations (with and without a highway barrier present) were consistent with our molecular results. We conclude that I-10 has reduced gene flow in a population of an important reptilian predator of the Sonoran Desert in southern Arizona and make conservation recommendations for reversing this trend.     

Utility of multispectral imaging for nuclear classification of routine clinical histopathology imagery

Background

We present an analysis of the utility of multispectral versus standard RGB imagery for routine H&;E stained histopathology images, in particular for pixel-level classification of nuclei. Our multispectral imagery has 29 spectral bands, spaced 10 nm within the visual range of 420–700 nm. It has been hypothesized that the additional spectral bands contain further information useful for classification as compared to the 3 standard bands of RGB imagery. We present analyses of our data designed to test this hypothesis.

Results

For classification using all available image bands, we find the best performance (equal tradeoff between detection rate and false alarm rate) is obtained from either the multispectral or our "ccd" RGB imagery, with an overall increase in performance of 0.79% compared to the next best performing image type. For classification using single image bands, the single best multispectral band (in the red portion of the spectrum) gave a performance increase of 0.57%, compared to performance of the single best RGB band (red). Additionally, red bands had the highest coefficients/preference in our classifiers. Principal components analysis of the multispectral imagery indicates only two significant image bands, which is not surprising given the presence of two stains.

Conclusion

Our results indicate that multispectral imagery for routine H&;E stained histopathology provides minimal additional spectral information for a pixel-level nuclear classification task than would standard RGB imagery.

     

Validation of 2D‐animated pictures as an investigative tool in the behavioural sciences: A case study with a West African cichlid fish,Pelvicachromis pulcher

Virtual stimuli represent an increasingly popular tool in the study of animal behaviour. Modern techniques have the potential to simplify and improve traditional experiments using live stimuli. However, the increasing availability of diverse techniques is associated with problems and limitations. Although many new methods have been developed, their validation remains largely untested. In the present study, we therefore performed two experiments to test whether 2‐D animations of predators and conspecifics elicit biologically appropriate behavioural responses in male rainbow kribs, Pelvicachromis pulcher. Individual responses towards a sympatric natural fish predator, Parachanna obscura, were tested using live predators and still colour photographs, animated using PowerPoint©. Compared to control trials (empty aquarium and white computer screen, respectively), individuals decreased their activity in response to both live and animated predators. We found no difference in activity between live and animation trials. Further, we tested individual aggression (frequency of aggressive behaviours) exhibited towards live and animated conspecifics. Individual aggressive behaviours shown towards live and animated conspecifics were positively correlated. Moreover, an individual's mean distance towards the opponent was a suitable proxy for individual aggression permitting the facilitation and standardisation of an individual's aggression through the use of a tracking software compared with the more laborious, traditional manual assessment. Our results show that simple, inexpensive animation techniques have the potential to provide an easy‐to‐apply and useful technological advance in animal behaviour research.     

Establishment of a doxycycline-regulated cell line with inducible,doubly-stable expression of the wild-type p53 gene from p53-deleted hepatocellular carcinoma cells

p53 is important in the development of hepatocellular carcinoma (HCC) and in therapeutic approaches, but the mechanism whereby it inhibits HCC growth is still unclear. The aim of the present study was to establish a HCC cell system in which p53 levels can be regulated. Full-length wild-type p53 cDNA obtained by PCR was cloned into a retroviral response vector controlled by the tetracycline responsive element (RevTRE-p53). The regulatory vectors RevTet-Off and RevTRE-p53 were transfected into a packaging cell line, PT67. Hep3B cells in which the p53 gene was deleted were infected with RevTet-Off viral particles from the PT67. Three G418-resistant cell clones with high luciferase expression and low background were infected with RevTRE-p53. By screening dozens of RevTRE-p53-infected clones with hygromycin we identified the one with the highest expression of p53 and the lowest background after doxycycline treatment. The results showed that p53 expression in this cell clone could be simply turned on or off by removing or adding doxycycline. Furthermore, it was found that the level of p53 protein was negatively and sensitively related to the doxycycline concentration. In conclusion, we have established a HCC cell line in which p53 expression can be switched on or off and regulated in a dose- and time-dependent manner.     

Success of maximum likelihood phylogeny inference in the four-taxon case

We used simulated data to investigate a number of properties of maximum- likelihood (ML) phylogenetic tree estimation for the case of four taxa. Simulated data were generated under a broad range of conditions, including wide variation in branch lengths, differences in the ratio of transition and transversion substitutions, and the absence of presence of gamma-distributed site-to-site rate variation. Data were analyzed in the ML framework with two different substitution models, and we compared the ability of the two models to reconstruct the correct topology. Although both models were inconsistent for some branch-length combinations in the presence of site-to-site variation, the models were efficient predictors of topology under most simulation conditions. We also examined the performance of the likelihood ratio (LR) test for significant positive interior branch length. This test was found to be misleading under many simulation conditions, rejecting too often under some simulation conditions. Under the null hypothesis of zero length internal branch, LR statistics are assumed to be asymptotically distributed chi 2(1); with limited data, the distribution of LR statistics under the null hypothesis varies from chi 2(1).      

Phylogenetic Community Context Influences Pollen Delivery to <Emphasis Type="Italic">Allium cernuum</Emphasis>

Few studies have examined how the number and identity of species in the neighbouring community influences the reproductive success of particular focal species. Pollen delivery, an important component of fitness of sexual plants, is a function of not just the floral traits of any particular individual, but of features of the population and community as it depends on pollinator abundance and preferences. Many pollinators in flowering communities will prefer patches with high floral abundance or diversity yet may exhibit lower floral constancy when more flowering species are present. Thus, pollination efficiency could increase or decrease with increased species richness and this will alter the selection pressures placed upon the floral traits (such as floral colour or reward) of any member of a particular community. Moreover, recent studies have indicated that plant-pollinator networks are phylogenetically structured (pollinators visit related plant species more than expected by chance) and this may be an important factor structuring flowering plant communities. Thus, the sheer number of species within a patch may be less important than the number of closely-related species. We investigate whether species richness or phylogenetic proximity of coflowering species influences the amount and proportion of conspecific pollen delivered to nodding onion, Allium cernuum, in fragment patches of Garry Oak meadows in South Western British Columbia, Canada. We find that pollen delivery depended upon the presence of close relatives far more than on species richness or population density, indicating a central role of the community structure on pollination in flowering plant communities. Insofar as pollen delivery relates to the relative number of seeds produced by members of the community, pollination may in turn determine the community structure of the next generation.     

Mutation of the RGD sequence does not affect plasma membrane association and growth inhibitory effects of elevated IGFBP-2 in vivo

Vacuolar sequestration or cellular extrusion of glutathione-conjugated xenobiotics and catabolites by ATP-binding cassette (ABC) transporters is an important detoxification mechanism operating in many species. In this study, we show that the yeast ABC transporter Bpt1p, a paralogue of Ycf1p, acts as an ATP-dependent vacuolar pump for glutathione conjugates. Bpt1p, which is inhibited by vanadate and glibenclamide, accounts for one third of the total vacuolar transport of glutathione conjugates. Furthermore, immunoblot analyses show that Bpt1p levels are strongly elevated in early stationary phase, consistent with a function of Bpt1p in vacuolar detoxification.