Stability, sensitivity, science and heurism

We examine recently proposed justifications of sensitivity analysis sensu Wheeler (1995 ), here referred to as weighted‐classes sensitivity analysis (WCSA). We refute Giribet's (2003a) claim that WCSA is the strictest possible test for a given phylogenetic hypothesis. Giribet's (2003a) classification of data exploration methods as evaluating “nodal stability” or “nodal support” is arbitrary, at odds with common usage and actually obscures the relationships between the methods he examined, all of which seek to assess the sensitivity of results to variation in analytical conditions. Stability, whether statistical or taxonomic, is not a goal of phylogenetic science. Statistical stability necessarily involves trial repetition, which is impossible in ideographic sciences like phylogenetics. Taxonomic stability can be nothing more than an unintended by‐product of scientific inquiry, i.e., the repeated failure to refute a hypothesis. Schulmeister's (2003 ) “robust‐choice” defense of WCSA does not succeed in placing non‐arbitrary bounds on parameters, and her interpretation of this approach as simultaneously verificationist and falsificationist is logically inconsistent. WCSA is neither scientific nor heuristic and therefore does not contribute to the advancement of objective knowledge claims. © The Willi Hennig Society 2005.     

Ribavirin: Biotechnological Synthesis and Effect on the Reproduction of Vaccinia Virus

The biotechnological method of synthesis of ribavirin, vidarabin, and 6-azauridine by the use of immobilized recombinant enzymatic preparations of nucleoside phosphorylase was improved. The effect of ribavirin and its combinations with the other synthesized nucleosides on the reproduction of Vaccinia virus was studied on the culture of Vero cells. The combination of ribavirin and vidarabin was shown to provide the antiviral effect at lesser concentrations than with these compounds taken separately.     

Distal arteriovenous fistula to maintain patency of the venous drainage of a latissimus dorsi flap following subclavian vein repair

Successful reconstructive surgery with muscle flaps depends on adequate arterial supply and undisturbed venous drainage. Combining such surgery with reconstructive vascular surgery of a large-caliber vein that is responsible for the venous drainage of the flap poses an additional challenge--the repaired vein's susceptibility to thrombosis. Every attempt must be made to prevent venous outflow obstruction following muscle flap surgery. Data from the vascular surgery literature demonstrate a low success rate for subclavian vein repair. The success rate with venous reconstructive surgery has been greater when a distal arteriovenous fistula accompanied the repair. The present case described the use of a temporary distal cephalic-brachial arteriovenous fistula to maintain the patency of the venous drainage of a pedicled latissimus dorsi muscle flap, following subclavian vein repair, for one-stage coverage of a large chest wall defect.     

Cracking the case: Seed traits and phylogeny predict time to germination in prairie restoration species

Traits are important for understanding how plant communities assemble and function, providing a common currency for studying ecological processes across species, locations, and habitat types. However, the majority of studies relating species traits to community assembly rely upon vegetative traits of mature plants. Seed traits, which are understudied relative to whole‐plant traits, are key to understanding assembly of plant communities. This is particularly true for restored communities, which are typically started de novo from seed, making seed germination a critical first step in community assembly and an early filter for plant establishment. We experimentally tested the effects of seed traits (mass, shape, and embryo to seed size ratio) and phylogeny on germination response in 32 species commonly used in prairie grassland restoration in the Midwestern USA, analyzing data using time‐to‐event (survival) analysis. As germination is also influenced by seed dormancy, and dormancy break treatments are commonly employed in restoration, we also tested the effects of two pretreatments (cold stratification and gibberellic acid application) on time to germination. Seed traits, phylogeny, and seed pretreatments all affected time to germination. Of all traits tested, variables related to seed shape (height and shape variance) best predicted germination response, with high‐variance (i.e., pointier and narrower) seeds germinating faster. Phylogenetic position (the location of species on the phylogenetic tree relative to other tested species) was also an important predictor of germination response, that is, closely related species showed similar patterns in time to germination. This was true despite the fact that all measured seed traits showed phylogenetic signal, therefore phylogeny provided residual information that was not already captured by measured seed traits. Seed traits, phylogenetic position, and germination pretreatments were important predictors of germination response for a suite of species commonly used in grassland restoration. Shape traits were especially important, while mass, often the only seed trait used in studies of community assembly, was not a strong predictor of germination timing. These findings illustrate the ecological importance of seed traits that are rarely incorporated into functional studies of plant communities. This information can also be used to advance restoration practice by guiding restoration planning and seed mix design.     

In vitro and in vivo neurogenic potential of mesenchymal stem cells isolated from different sources

Regenerative medicine is an evolving interdisciplinary topic of research involving numerous technological methods that utilize stem cells to repair damaged tissues. Particularly, mesenchymal stem cells (MSCs) are a great tool in regenerative medicine because of their lack of tumorogenicity, immunogenicity and ability to perform immunomodulatory as well as anti-inflammatory functions. Numerous studies have investigated the role of MSCs in tissue repair and modulation of allogeneic immune responses. MSCs derived from different sources hold unique regenerative potential as they are self-renewing and can differentiate into chondrocytes, osteoblasts, adipocytes, cardiomyocytes, hepatocytes, endothelial and neuronal cells, among which neuronal-like cells have gained special interest. MSCs also have the ability to secrete multiple bioactive molecules capable of stimulating recovery of injured cells and inhibiting inflammation. In this review we focus on neural differentiation potential of MSCs isolated from different sources and how certain growth factors/small molecules can be used to derive neuronal phenotypes from MSCs. We also discuss the efficacy of MSCs when transplanted in vivo and how they can generate certain neurons and lead to relief or recovery of the diseased condition. Furthermore, we have tried to evaluate the appropriate merits of different sources of MSCs with respect to their propensity towards neurological differentiation as well as their effectiveness in preclinical studies.     

Time-course of pathogen induced accumulation of callose as mechanical protective barrier in wheat seedlings

Results of fluorescence microscopic study and quantitative luminescent analysis of pathogen induced callose accumulation in winter wheat seedlings of two cultivars with different resistance to causal agent of eyespot disease are presented. Higher content of constitutive callose in intact seedlings of unsusceptible cultivar at the initial stages of vegetation was determined. It correlates with resistance of this cultivar to Pseudocercosporella herpotrichoides—causal agent of eyespot disease. The increased pathogen induced accumulation of callose in seedlings of susceptible cultivar was revealed, however, it did not influence it protection against pathogen.     

Activity of the Fe-Branch of Tetrapyrrole Biosynthesis in the Chlorophyll-Deficient Plastome Mutant of Sunflower

The biosynthesis of heme, a plant tetrapyrrole, was studied in the leaves of a chlorophyll-deficient plastome mutant of the sunflower (Helianthus annuus L, line 2-24, albina form). In the light, the content of 5-aminolevulinic acid (ALA) in white mutant leaves was, on the average, ten times less than in that of the wild-type form (line 3629). Chlorophyll content in mutant leaves comprised only 0.3% of that of control plants. The activities of Fe-chelatase and ALA dehydratase in the heme synthesis were either comparable to or even higher than those in the wild-type leaves. A normal respiration rate in white mutant leaves, the equal content of phytochrome apoproteins in plants of both types, and the lack of noticeable morphogenetic differences realized through the phytochrome system can indicate that mutant and wild-type leaves are similar in their levels of phytochrome and the cytochromes of mitochondrial respiration. Nevertheless, in the mutant, the content of heme noncovalently bound by apoproteins amounted to only one third of its content in the wild-type plants. It seems that a dramatic decrease in the capability of white leaves for chlorophyll biosynthesis and for the formation of the photosynthetic apparatus is responsible for a low demand for chloroplast cytochromes, which is the major cause of a reduced heme content in the mutant.     

Comparative evaluation of methods of inducing Brucella L forms and a study of their adaptibility in the body of animals]

The action of bicillin-3 on Brucella directly in the body of animals enhances their potential ability to convert into L-forms. One of the factors contributing to the generalization of the infection caused by the L-forms of Brucella and to their prolonged persistance in the body is the presence of an L-transforming agent (in this case, bicillin-3), which indicate that the appearing L-forms of Brucella are obviously antibiotic-dependent.     

Plausible prebiotic synthesis of aldopentoses from simple substrates, glycolaldehyde and formaldehyde

Possible ways of abiotic catalytic synthesis of biologically significant aldopentoses (ribose, xylose, arabinose, lyxose) from elementary substrates, i.e., formaldehyde (FA) and glycolaldehyde (GA) in aqueous solutions are discussed. Conditions in which the process of synthesis of pentoses yields up to 65% relative to the initial concentration of GA: homogeneous borate catalyst NaOH + H₃BO₃, pH 9, [GA]₀ 5 mM, [FA]₀ 50–100 mM have been found.