Stereological Determination of Orientations,Second-Order Quantities and Correlations for Random Spatial Fibre Systems

This paper presents methods for the stereological analysis of spatial fibre systems on the base of planar or thin sections. Under the assumption that the cross-section figures of the tubular fibres can be measured, the orientation distribution of the fibre system and its line density L_v can be determined from one section only and without distributional assumptions. A simple way to study the degree of randomness of fibre systems consists in the statistical analysis of the point pattern of centres of intersection figures. More sophisticated methods are of stereological nature and yield the spatial reduced second moment measure. Similarly also correlations between two fibre systems can be quantified. The methods are demonstrated by two examples concerning samples of human brain.     

A Mathematical Framework for Combining Decisions of Multiple Experts toward Accurate and Remote Diagnosis of Malaria Using Tele-Microscopy

We propose a methodology for digitally fusing diagnostic decisions made by multiple medical experts in order to improve accuracy of diagnosis. Toward this goal, we report an experimental study involving nine experts, where each one was given more than 8,000 digital microscopic images of individual human red blood cells and asked to identify malaria infected cells. The results of this experiment reveal that even highly trained medical experts are not always self-consistent in their diagnostic decisions and that there exists a fair level of disagreement among experts, even for binary decisions (i.e., infected vs. uninfected). To tackle this general medical diagnosis problem, we propose a probabilistic algorithm to fuse the decisions made by trained medical experts to robustly achieve higher levels of accuracy when compared to individual experts making such decisions. By modelling the decisions of experts as a three component mixture model and solving for the underlying parameters using the Expectation Maximisation algorithm, we demonstrate the efficacy of our approach which significantly improves the overall diagnostic accuracy of malaria infected cells. Additionally, we present a mathematical framework for performing ‘slide-level’ diagnosis by using individual ‘cell-level’ diagnosis data, shedding more light on the statistical rules that should govern the routine practice in examination of e.g., thin blood smear samples. This framework could be generalized for various other tele-pathology needs, and can be used by trained experts within an efficient tele-medicine platform.     

Immunological evidence for the existence of H1-like histone in yeast

In view of the controversies about the existence of histone H1 in yeast we have reinvestigated the problem by studying yeast proteins extracted with perchloric acid and salt. Perchloric-acid-extracted proteins from whole cells contain only two fractions which comigrate with 'authentic' yeast high-mobility-group proteins (HMG) in both SDS and acid urea gels. These extracts show a considerable cross-reaction with anti-(calf thymus HMG) antiserum and do not react with antiserum to mouse liver H1. The isolation of 'authentic' yeast HMG by the standard salt/trichloroacetic acid procedure gives two types of preparations containing different numbers of protein bands. The poorer preparation reacts only with the anti-HMG antiserum whereas the richer preparation also gives considerable cross-reaction with the anti-H1 antiserum. Immunoblotting analysis performed on the salt-extracted proteins reveals the presence of three protein bands giving positive immunoreaction with the anti-H1 antiserum. The immunoreactive bands have electrophoretic mobilities close to that of the marker calf thymus H1 and similar to the mobilities of the presumptive yeast H1 fractions found by other authors.     

Protein kinase C activity is rate limiting for shedding of the interleukin-6 receptor.

An analysis of the mechanism of generation of the soluble interleukin-6 receptor (IL-6R) has been performed. The membrane-bound receptor is proteolytically cleaved to release a soluble receptor form which retained its ligand binding capacity. Furthermore, the soluble IL-6R is unique in its ability to induce a biological signal in complex with the ligand interleukin-6 (IL-6) on cells which by themselves do not bind IL-6. Shedding of the IL-6R is strongly activated by PMA and can be inhibited by the protein kinase inhibitor staurosporine. The generation of the IL-6R is not dependent on protein synthesis. The inactive PMA analogue 4-alpha-phorbol-12,13-didecanoate fails to induce shedding of the IL-6R. Transfection of a protein kinase C expression plasmid into IL-6R expressing cells leads to enhanced shedding of the receptor. These experiments clearly show that protein kinase C regulates shedding of the IL-6R.     

Application of comet assay for the assessment of DNA damage caused by chemical genotoxins in the dairy yeast Kluyveromyces lactis

Kluyveromyces lactis, also known as dairy yeast, has numerous applications in scientific research and practice. It has been approved as a GRAS (Generally Recognized As Safe) organism, a probiotic, a biotechnological producer of important enzymes at industrial scale and a bioremediator of waste water from the dairy industry. Despite these important practical applications the sensitivity of this organism to genotoxic substances has not yet been assessed. In order to evaluate the response of K. lactis cells to genotoxic agents we have applied several compounds with well-known cyto- and genotoxic activity. The method of comet assay (CA) widely used for the assessment of DNA damages is presented here with new special modifications appropriate for K. lactis cells. The comparison of the response of K. lactis to genotoxins with that of Saccharomyces cerevisiae showed that both yeasts, although considered close relatives, exhibit species-specific sensitivity toward the genotoxins examined.     

Perinatal physiology in cloned and normal calves: hematologic and biochemical profiles

Although a majority of clones are born normal and apparently healthy, mortality rates of nearly 30% are described in many reports. Such losses are a major limitation of cloning technology and represent substantial economic investment as well as justifiable animal health and welfare concerns. Prospective, controlled studies are needed to understand fully the causes of neonatal mortality in clones and to develop preventive and therapeutic strategies to minimize losses. We report here the findings of studies on the hematologic and biochemical profiles of cloned and control calves in the immediate 48-h postpartum period. Cloned calves were similar to control calves for a majority of parameters studied including blood gases, concentrations of plasma proteins, minerals and electrolytes, and white blood cell, neutrophil, lymphocyte, and platelet counts. The most notable differences between clones and controls in this study were reduced red- and white-blood cell counts in clones at birth and 1 h of age. As a group, plasma electrolyte concentrations were more variable in clones, and the variability tended to be shifted either higher (sodium, chloride) or lower (potassium, bicarbonate) than in controls. Previously, we noted differences in carbohydrate parameters, the length of time required for clones to make the neonatal adaptation to life ex utero, and morphology of the cloned placenta. Taken together, our findings suggest that cloned calves experience greater difficulty adjusting to life ex utero and that further research is warranted to determine the nature of the relationship between the physiological differences noted here in clones at birth and concomitant abnormal placental morphology.     

Inner kinetochore of the pathogenic yeast Candida glabrata

The human pathogenic yeast Candida glabrata is the second most common Candida pathogen after Candida albicans, causing both bloodstream and mucosal infections. The centromere (CEN) DNA of C. glabrata (CgCEN), although structurally very similar to that of Saccharomyces cerevisiae, is not functional in S. cerevisiae. To further examine the structure of the C. glabrata inner kinetochore, we isolated several C. glabrata homologs of S. cerevisiae inner kinetochore protein genes, namely, genes for components of the CBF3 complex (Ndc10p, Cep3p, and Ctf13p) and genes for the proteins Mif2p and Cse4p. The amino acid sequence identities of these proteins were 32 to 49% relative to S. cerevisiae. CgNDC10, CgCEP3, and CgCTF13 are required for growth in C. glabrata and are specifically found at CgCEN, as demonstrated by chromatin immunoprecipitation experiments. Cross-complementation experiments revealed that the isolated genes, with the exception of CgCSE4, are species specific and cannot functionally substitute for the corresponding genes in S. cerevisiae deletion strains. Likewise, the S. cerevisiae CBF3 genes NDC10, CEP3, and CTF13 cannot functionally replace their homologs in C. glabrata CBF3 deletion strains. Two-hybrid analysis revealed several interactions between these proteins, all of which were previously reported for the inner kinetochore proteins of S. cerevisiae. Our findings indicate that although many of the inner kinetochore components have evolved considerably between the two closely related species, the organization of the C. glabrata inner kinetochore is similar to that in S. cerevisiae.