Further Investigations on the Robustness of the Standardized Selection Difference

The robustness of the standardized selection difference is investigated for the family of central chi-squared-distributions. The results are compared with those for the uniform, a family of triangular distributions and the exponential distribution. Beside these exact results and some simulation results are considered.     

Gnotobiotic studies to determine the colonization resistance of the intestines

The literature data and the results of the author studies on determination of intestine colonization resistance are presented. The mechanisms of the colonization resistance defined by the macroorganism factors and representatives of indigenic microflora are discussed. The results of the experiments with animal gnotobiotes aimed at elucidating new aspects of the colonization resistance mechanism: antagonistic interrelations between pathogenic and nonpathogenic bacteria and the role of transitory microflora, factors lowering the colonization resistance are presented. The up-to-date methods for testing the colonization resistance and the ways for its increasing are indicated.     

Kinetics of the transient-phase and steady-state of the monocyclic enzyme cascades

We present a kinetic analysis of the whole course of the reaction, that is, of both the transient-phase and steady-state, of monocyclic enzyme cascade systems. The equations for the rapid equilibrium conditions are obtained as a particular case of the general transient-phase equations. An analysis of the kinetic data allows the determination of the equilibrium and the rate constants if adequate experimental results are available. Finally, our results for the steady-state are compared with those obtained by other authors.     

The electrostatic field of DNA: the role of the nucleic acid conformation.

Calculations of the electrostatic field of DNA in two very different double helical conformations, A and Z, are reported and compared with the results previously obtained for B-DNA. Striking contrasts between these fields and the associated electrostatic potentials are brought into evidence. One of the major differences is that while the deepest potentials are generally located in the grooves of DNA, the strongest fields are associated with the phosphate groups. The results of screening the nucleic acids by counterions are also presented.     

A mathematical model of the regulation system of the secretion of glucocorticoids

We propose a mathematical model for the regulation system of the secretion of glucocorticoids and determined the coefficients in the system of ordinary differential equations. Some results are calculated which agree with the experimental results.     

Influence of the g-force on the circumnutations of sunflower hypocotyls

Circumnutations of hypocotyls of sunflower ( Helianthus annuus L. cv. Californicus) were studied under 1 g and 3 g conditions. Root mean square values of the hypocotyl deviation from the plumbline and period of the movements were determined from Calculations of the autocorrelation functions of the movements. The amplitude and the period of the circumnutations increased under 3 g as compared to 1 g . A transition from 3 to 1 g or vice versa also caused changes in period and amplitude of the movoments. The results are interpreted as a support for the idea that gravity influences the circumnutation parameters in this sunflower variety. A comparison is made with published results on the dwarf sunflower ev. Teddy Bear where the force influence is very small or negligible. Simulations of a model for circumnutations show movements which are in qualitative agreement with the experimental results, provided adaptation to g -levels is included in the model. Finally, the results are discussed with the recent Spacelab-experiment (SLI) as a background.     

Re-evaluating the recycling hypothesis in the germinal centre

Mathematical models have been used to study different aspects of the germinal centre reaction, in particular, affinity maturation of antibodies and the hypothesis of recycling. So far, interpretation of several theoretical and experimental results has pointed to the existence of recycling. However, theoretical models have seldom been compared with experimental data from specific immune responses and the potential relevance of recycling in the germinal centre is still an open problem. In this article, we propose a model without recycling that takes into account selection mechanisms that were previously uncovered experimentally. We apply the model to several experimental systems that use different Ag and compare the results with experimental data of affinity maturation whenever available. The results obtained for a primary immune response to the hapten (4-hydroxy-3-nitrophenyl)-acetyl show that recycling is not a necessary mechanism to achieve the level of affinity maturation observed in germinal centre reactions. Similar levels of affinity maturation are obtained for other responses, although for antibodies involving several affinity-enhancing mutations the affinity maturation obtained with the model is much lower. Interpretation of these results and consequences towards the concept of recycling are discussed.     

Identification of the metal associated with the insulin degrading enzyme.

Insulin degrading enzyme (IDE) is a thiol-dependent metalloendoprotease that is responsible for initiation of cellular insulin degradation. However, its exact mode of action and the factors controlling it are poorly understood. Since IDE is a metal requiring enzyme, we have examined which metal(s) is(are) endogenously associated with it. Using neutron activation analysis, we studied the metal content of a partially purified enzyme from three different tissues: rat skeletal muscle, rat liver, and human placenta. Our results indicate that zinc and manganese are associated with the enzyme with approximately 10 times more zinc as manganese being present. These results suggest that one or both of these two metals are endogenously associated with this enzyme and are a means of controlling the enzyme's activity.     

Farnesyl transferase inhibitors block the farnesylation of CENP-E and CENP-F and alter the association of CENP-E with the microtubules

Human tumor cell lines that are sensitive to the effects of farnesyl transferase inhibitors accumulate in G(2) --> M (except for cells with an activated Ha-ras that accumulate in G(1)). A search for CAAX box proteins from Swiss-Prot revealed more than 300 peptides. Of these, the centromeric proteins CENP-E and CENP-F are preferentially expressed during mitosis and are implicated as mediators of the G(2) --> M checkpoint. Experiments performed here show that peptides from the COOH-terminal CAAX box of CENP-E and CENP-F are substrates for farnesyl transferase but not geranylgeranyl transferase-I. Although both proteins are prenylated in the human tumor cell line DLD-1, their prenylation is completely inhibited by the farnesyl transferase inhibitor, SCH 66336. Immunohistochemical data with the lung carcinoma cell line, A549, showed that preventing the farnesylation of CENP-E and CENP-F by treatment with the farnesyl transferase inhibitor SCH 66336 does not affect their localization to the kinetochores. However, the presence of farnesyl transferase inhibitors alters the association between CENP-E and the microtubules. Our results imply that the inhibition of CENP-E farnesylation results in the alteration of the microtubule-centromere interaction during mitosis and results in the accumulation of cells prior to metaphase.     

Argon laser treatment of port-wine stains: the patients' evaluations of the result.

The argon laser is now a well-established method of treating port-wine stains (PWS) in the face and neck areas. Satisfactory results are reported in 44 to 75 percent of cases, but criteria for that classification and the patients' perceptions of the result are seldom given. In the present paper, a sample of 58 patients was used to assess the patients' own perceptions of the degree of lightening and scarring. Three felt the results were excellent, 23 good, 18 fair, and 14 poor. The treatment was considered as unpleasant by 76 percent, and 55 percent of the patients asked for a new consultation. Scarring was noticed by 50 percent. The patients' perceptions of the results and physicians' rating were the same in 69 percent. The best results were obtained in older patients with small port-wine stains. Such lesions also can be treated surgically with good results.     

Assessing the numerical accuracy of the impedance method

The impedance method has been used extensively to calculate induced electric fields and currents in tissue as a result of applied electromagnetic fields. However, there has previously been no known method for an a priori assessment of the numerical accuracy of the results found by this method. Here, we present a method which permits an a priori assessment of the numerical accuracy of the impedance method applied to physiologically meaningful problems in bioengineering. The assessment method relies on estimating the condition number associated with the impedance matrix for problems with varying shapes, sizes, conductivities, anisotropies, and implementation strategies. Equations have been provided which predict the number of significant figures lost due to poor matrix conditioning as a function of these variables. The results show that, for problems of moderate size and uncomplicated geometry, applied fields should be measured or calculated accurately to at least five or six significant figures. As resolutions are increased and material properties are more widely divergent even more significant figures are needed. The equations provided here should ensure that solutions found from the impedance method are calculated accurately.     

Dependence of the results of a genetic analysis of self-pollinating cereal species on the specificity of the mapping population

The available in literature information as for results of genetic analysis of several self-pollinating cereal species involving the use of plant lines with alien genetic material as the object of analysis is summarized. The restrictions caused by specificity of the investigated material as for the possible explanation of the obtained results are emphasized. Several suggestions concerning the preliminary study of introgressive plant lines before their including into experimental programs on genetic analysis are made.     

Expansion of the master equation for a biomolecular selection model

A stochastic model based on Eigen and Schuster's theory of biomolecular self-replication is studied by treating the master equation with the system-size expansion technique. The steady-state results are found to be in good agreement with the previous results and with those derived from the principle of detailed balancing. Multispecies competition and coexistence are studied carefully with the conclusions that a stable steady state is predicted for the former and a metastable state for the latter. The stochastic selection processes are also analyzed and discussed.     

The genetic linkage between the PKU locus and the loci for Amylase1, Amylase2, Fy,PGM1, and Rh and the question of assignment of the PKU locus to chromosome No. 1

Summary The alpha-amylase loci Amy₁ and Amy₂ and other loci on chromosome 1 were investigated for their linkage relationship to the PKU locus. Ten families were informative for the study of linkage between PKU/Amy, 20 for PKU-Fy, 11 for PKU/PGM₁, and 10 for PKU/Rh linkage. The probabilities of linkage at different recombinant fractions were calculated according to Bayes' theorem. The results are in striking contrast with those of Kamaryt et al. who found strong evidence for close linkage between the amylase loci and the PKU locus, whereas with our results close linkage can be excluded; loose linkage is possible but unlikely. The results are discussed with regard to the genetic heterogeneity of phenylketonuria.     

The role of the osphradium in chemoreception by the snail Biomphalaria glabrata (Say)

The possible involvement of the osphradium of Biomphalaria glabrata (Say) in food finding has been investigated by using behavioural assays to determine whether snails with cauterized osphradial canals can locate a source of food extract in still water. A new technique for anaesthetizing the snails for the cautery experiments is described. The experimental results indicate that a functional osphradium is not essential for directional movement towards a source of food extract. The present results are in conflict with those of Michelson (1960). Reasons for the differences between the present results and those of Michelson and the possible functional roles of the osphradium are discussed.     

Results of the implementation of the System for the Integrated Assessment of Protected Areas (SIAPA) to the protected areas of the Autonomous Region of Madrid (Spain)

The long-term conservation of biodiversity and related ecosystems goods and services of the Autonomous Region of Madrid is jeopardized by the intensive resource-consuming development model followed by the region in the past few decades. This paper presents the aggregated results of the first integrated assessment of the protected areas of the Autonomous Region of Madrid (Spain) with the System for the Integrated Assessment of Protected Areas (SIAPA). Detailed results are also provided for individual protected areas as supplementary data. The assessment was done during 2009–2010, on ten protected areas differing in their sizes (from 2.5 to 52,796 ha), protection categories (seven categories) and types of ecosystems present. Comparison of results from both assessment models of the SIAPA (the Complete Model and the Simplified Model) is also presented. The results from the Complete Model show that eight out of the ten protected areas of the Autonomous Region of Madrid are currently ineffective. The poorest partial indexes overall were: “State of Conservation” and “Social and Economic Context”. The only indexes significantly correlated with the effectiveness of a protected area were: the “State of Conservation” (r = 0.851**) and the “Social Perception and Valuation” (r = 0.786**). Although not as relevant as was thought, “Management” and the other non-significant factors are likely to influence the effectiveness of protected areas as well. The results for the Simplified Model are slightly better than those for the Complete Model, although this is probably a specific result of this assessment. The two models of the SIAPA were very significantly correlated, although their aggregated results should not be compared directly.     

Study of the surface barrier discharge generated by electrodes in the form of a series of parallel metal strips

A surface discharge in a system where metal electrodes in the form of a series of parallel strips are positioned on the dielectric surface is studied. Analytical formulas for calculating the spatial distribution of the potential and the electric field in a discharge cell are derived. It is shown that the geometry of the metal electrodes should be taken into account (along with physical and chemical characteristics of the dielectric, the voltage applied to the electrodes, and other parameters of the system) for generation of the electric field with optimal configuration in the discharge cell. The obtained results are also applicable for analysis of discharge cells with a coplanar barrier discharge where metal electrodes are positioned in the dielectric at small depths. The results are of interest since a barrier discharge is one of the efficient methods for generating non-equilibrium plasma at high pressures for a variety of technological applications.     

An intergral method for the analysis of flow in arterial stenoses

An approximate solution is presented to the problem of incompressible flow through an axisymmetric constriction. The geometry is intended to simulate an arterial stenosis, and the solution is applicable to both mild and severe stenoses for Reynolds numbers below transition. Theoretical results obtained for specific geometries are given for the velocity distribution, pressure drop, wall shearing stress, and separation phenomena. These results reveal the significant alterations in flow caused by a stenosis. Experiments using model stenoses are described and compared with the theoretical results. Theoretical predictions of pressure drop and separation characteristics are in reasonably good agreement with the experimental observations.     

Towards a framework for the study of the neural correlates of aesthetic preference

Aiming to provide a tentative framework for the study of the neural correlates of aesthetic preference, we review three recent neuroimaging studies carried out with the purpose of locating brain activity associated with decisions about the beauty of visual stimuli (Cela-Conde et al., 2004; Kawabata and Zeki, 2004; Vartanian and Goel, 2004). We find that the results of the three studies are not in line with previous neuropsychological data. Moreover, there are no coincidences among their results. However, when they are mapped on to Chatterjee's (2003) neuropsychological model of aesthetic preference it becomes clear that neuroimaging data are not contradictory, but complementary, and their interpretation is enriched. The results of these studies suggest that affective processes have an important role in aesthetic preference, and that they are integrated with cognitive processes to reach a decision regarding the beauty of visual stimuli. Future studies must aim to clarify whether certain methodological procedures are better suited to study any of the particular cognitive operations involved in aesthetic preference, and ascertain the extent to which the proposed framework is compatible with the aesthetic appreciation of musical stimuli.     

The Use of the A.P.I. Lactobacillus System for the Characterization of Pediococci

A commercially produced system for the identification of Lactobacillus , by which the reactions of concentrated cell suspensions towards 50 substrates may be determined, is useful for the characterization of strains of Pediococcus . Suitable conditions for inoculum preparation vary for slow and fast growing strains; the influence of cell concentration on the results is described. The reactions are classified in terms of their value for species characterization and the results are shown to agree well with those in other studies where classical procedures have been used.