On structure preserving quantisations

Maps of functions on classical phase space to quantum operators do not preserve the algebraic structure. After locating the algebraic reasons for it, the problem of quantisation is redefined and the Moyal bracket is discussed for its structure preservation. This quantisation entails the inclusion of Schwartz distributions to the space of classical functions

Translocation of plasminogen activator inhibitor-1 during serum stimulated growth of mouse embryo fibroblasts

Serum-stimulated mouse embryo fibroblasts specifically secrete two proteins of molecular weights 48,000 and 26,000. The 48 kDa protein showed affinity to concanavalin A and was precipitated by antibody to plasminogen activator inhibitor. Immunoflowcytometry using anti plasminogen activator inhibitor-1 serum indicate the presence of the 48 kDa protein in quiescent cells; this protein was virtually absent in serum-stimulated cells. The presence of the plasminogen activator inhibitor-1 related protein in quiescent cells and its absence in serum-stimulated cells in combination with the observation on the absence of this protein, in the medium of quiescent cells and its presence in the medium of stimulated cells indicate that the 48 kDa protein was transferred from the cells into the medium upon serum-stimulation. The serum-mediated transfer of plasminogen activator inhibitor-1 from the cells into the medium was inhibited by actinomycin-D suggesting that the transfer process required actinomycin-D sensitive events. Treatment of pre-labelled quiescent cells with medium containing 20% fetal calf serum resulted in the gradual transfer of the labelled 48 kDa protein to the extra cellular matrix. These studies indicate that exposure of quiescent cells to fetal calf serum results in the transfer of plasminogen activator inhibitor-1 from the cells to the growth mediumvia extracellular matrix. The translocation of the protease inhibitor from the cells to the matrix and medium may enable the cellular and possibly the membrane proteases to act on growth factors or their receptors thereby initiating the mitogenic response

Purification and characterization of a DNA synthesis inhibitor protein from mouse embryo fibroblasts

A DNA synthesis inhibitor protein was purified from the conditioned medium of cycloheximide treated mouse embryo fibroblasts. This protein has a molecular weight of 45,000 as determined by gel filtration and Polyacrylamide gel electrophoresis. The levels of the [35S] methionine la belled 45 kDa protein in the medium and matrix were monitored across two cell cycles in synchronized cultures. The 45 kDa protein was present in higher levels in the medium of non-S-phase cells depicting a peak between the two S- phases. The DNA synthesis inhibitor protein was immunologically related to a chicken DNA-binding protein which showed similar cell cycle specific variations at the intracellular level. The purified 45 kDa protein inhibited DNA synthesis in murine and human cells. In mouse embryo fibroblasts, the DNA synthesis was inhibited to an extent of 86% by 0 · 25 μg/ml of the inhibitor, while higher amounts of the inhibitor were required to arrest DNA synthesis in human skin fibroblasts: in these cells, 4 μg/ml of the inhibitor inhibited DNA synthesis to an extent of 50%. The high levels of the 45 kDa protein in the medium of non-S phase cells and its DNA synthesis inhibitory potential suggest that this protein may be involved in the regulation of DNA synthesis during the cell cycle

Limited predictive value of blastomere angle of division in trophectoderm and inner cell mass specification.

The formation of trophectoderm (TE) and pluripotent inner cell mass (ICM) is one of the earliest events during mammalian embryogenesis. It is believed that the orientation of division of polarised blastomeres in the 8- and 16-cell stage embryo determines the fate of daughter cells, based on how asymmetrically distributed lineage determinants are segregated. To investigate the relationship between angle of division and subsequent fate in unperturbed embryos, we constructed cellular resolution digital representations of the development of mouse embryos from the morula to early blastocyst stage, based on 4D confocal image volumes. We find that at the 16-cell stage, very few inside cells are initially produced as a result of cell division, but that the number increases due to cell movement. Contrary to expectations, outside cells at the 16-cell stage represent a heterogeneous population, with some fated to contributing exclusively to the TE and others capable of contributing to both the TE and ICM. Our data support the view that factors other than the angle of division, such as the position of a blastomere, play a major role in the specification of TE and ICM.This work was supported through a Wellcome Trust fellowship award [074246/Z04/Z] and Biotechnology and Biological Sciences Research Council grants [BB/F011512/1 and BB/E004946/1] to S.S.This is the final published version. It first appeared at dev.biologists.org/content/141/11/2279.long

Mapping of risk prone areas of kala-azar (Visceral leishmaniasis) in parts of Bihar state, India: An RS and GIS approach

Background & objectives: The kala-azar fever (Visceral leishmaniasis) is continuing unabated in India for over a century, now being largely confined to the eastern part of India mainly in Bihar state and to some extent in its bordering states like West Bengal and Uttar Pradesh. Two study sites namely Patepur block in Vaishali district with high endemicity in northern part and Lohardagga block in Lohardagga district with absolute non-endemicity in southern part of Bihar were selected for the study with the following objectives : (i) to study the macro-ecosystem in relation to distribution of vector -Phlebotomus argentipes; (ii) to identify/map the risk prone areas or villages in a block for quick remedial measures; and (iii) to make use of satellite remote sensing and GIS to demonstrate the utility for rapid assessment of landuse/landcover and their relation with the incidence of kala-azar leading to the mapping of risk prone areas. Methods: Indian Remote Sensing (IRS)-1D LISS III satellite data for the periods of March and November 2000 were analysed in Silicon graphic image processing system using ERDAS software. False color composites (FCC) were generated and landuse/landcover was assessed using Maximum likelihood supervised classification techniques based on ground truth training sets. During the study the GIS functions are used to quantify the remotely sensed landscape proportions of 5 km 2 buffer surrounding each known group of villages of high occurrence of sandflies in endemic and non-endemic study sites. Instead of traditional ground based survey methods to vector surveillance, the present study used a combination of remote sensing (RS) and geographical information system (GIS) approach to develop landscape predictors of sandfly abundance-an indicator of human vector contact and as a measure of risk prone areas. Results: Statistical analysis using the remotely sensed landscape variables showed that rural villages surrounded by higher proportion of transitional swamps with soft stemmed edible plants and banana, sugarcane plantations had higher sandfly abundance and would, therefore, be at higher risk prone areas for man-vector contact. Interpretation & conclusion: The present study clearly brought out the usefulness of satellite remote sensing technology in generating the crucial information on spatial distribution of landuse/landcover classes with special emphasis on indicator landcover classes thereby helping in prioritising the area to identify risk prone areas of kala-azar through GIS application tools

Mapping of risk prone areas of kala-azar (Visceral leishmaniasis) in parts of Bihar state, India: an RS and GIS approach

Background & objectives: The kala-azar fever (Visceral leishmaniasis) is continuing unabated inIndia for over a century, now being largely confined to the eastern part of India mainly in Bihar stateand to some extent in its bordering states like West Bengal and Uttar Pradesh. Two study sites namelyPatepur block in Vaishali district with high endemicity in northern part and Lohardagga block inLohardagga district with absolute non-endemicity in southern part of Bihar were selected for thestudy with the following objectives : (i) to study the macro-ecosystem in relation to distribution ofvector —Phlebotomus argentipes; (ii) to identify/map the risk prone areas or villages in a block forquick remedial measures; and (iii) to make use of satellite remote sensing and GIS to demonstratethe utility for rapid assessment of landuse/landcover and their relation with the incidence of kalaazarleading to the mapping of risk prone areas.Methods: Indian Remote Sensing (IRS)-1D LISS III satellite data for the periods of March andNovember 2000 were analysed in Silicon graphic image processing system using ERDAS software.False color composites (FCC) were generated and landuse/landcover was assessed using Maximumlikelihood supervised classification techniques based on ground truth training sets. During the studythe GIS functions are used to quantify the remotely sensed landscape proportions of 5 km2 buffersurrounding each known group of villages of high occurrence of sandflies in endemic and nonendemicstudy sites. Instead of traditional ground based survey methods to vector surveillance, thepresent study used a combination of remote sensing (RS) and geographical information system (GIS)approach to develop landscape predictors of sandfly abundance—an indicator of human vector contactand as a measure of risk prone areas.Results: Statistical analysis using the remotely sensed landscape variables showed that rural villagessurrounded by higher proportion of transitional swamps with soft stemmed edible plants and banana,sugarcane plantations had higher sandfly abundance and would, therefore, be at higher risk proneareas for man-vector contact.Interpretation & conclusion: The present study clearly brought out the usefulness of satellite remotesensing technology in generating the crucial information on spatial distribution of landuse/landcoverclasses with special emphasis on indicator landcover classes thereby helping in prioritising the areato identify risk prone areas of kala-azar through GIS application tools

Active cell migration drives the unilateral movements of the anterior visceral endoderm

The anterior visceral endoderm (AVE) of the mouse embryo is a specialised extra-embryonic tissue that is essential for anterior patterning of the embryo. It is characterised by the expression of anterior markers such as Hex, Cerberus-like and Lhx1. At pre-gastrula stages, cells of the AVE are initially located at the distal tip of the embryo, but they then move unilaterally to the future anterior. This movement is essential for converting the existing proximodistal axis into an anteroposterior axis. To investigate this process, we developed a culture system capable of imaging embryos in real time with single cell resolution. Our results show that AVE cells continuously change shape and project filopodial processes in their direction of motion, suggesting that they are actively migrating. Their proximal movement stops abruptly at the junction of the epiblast and extra-embryonic ectoderm, whereupon they move laterally. Confocal microscope images show that AVE cells migrate as a single layer in direct contact with the epiblast, suggesting that this tissue might provide directional cues. Together, these results show that the anteroposterior axis is correctly positioned by the active movement of cells of the AVE in response to cues from their environment, and by a 'barrier' to their movement that provides an endpoint for this migration