In the fission yeast, Schizosacchromyces pombe, blocks to DNA replication elongation trigger the intra-S phase checkpoint that leads to the activation of the Cds1 kinase. Cds1 is required to both stabilize stalled replication forks and to prevent premature entry into mitosis. Interestingly, although Cds1 is essential to maintain the viability of mutants defective in DNA replication elongation, my study shows that mutants defective in DNA replication initiation require the Chk1 kinase, rather than Cds1. This suggests that failed initiation events can lead to activation of the DNA damage checkpoint independent of the intra-S phase checkpoint. This might result from reduced origin firing that leads to an increase in replication fork stalling or replication fork collapse that activates the G2 DNA damage checkpoint. I refer to the Chk1-dependent, Cds1-independent phenotype as the rid phenotype (for replication initiation defective). The data shows that Chk1 is active in rid mutants when grown under semi-permissive conditions, and rid mutant viability is dependent on the DNA damage checkpoint, and surprisingly Mrc1, an adaptor protein required for activation of Cds1. Mutations in Mrc1 that prevent activation of Cds1 have no effect on its ability to support rid mutant viability, suggesting that Mrc1 has a checkpoint-independent role in maintaining the viability of mutants defective in DNA replication initiation. Like Mrc1, Swi1 and Swi3 have been hypothesized as a part of the replication fork protection complex (RFPC). They are required for maintaining the viability of rid mutants, but are not essential for activation of Chk1 in response to failed initiation events. This suggests that Mrc1 in conjunction with Swi1 and Swi3 function in a similar pathway to alleviate replicative stress resulting from defects in DNA replication initiation. Using flow cytometry, I demonstrate that inhibition of DNA replication initiation has no significant impact on the duration of S phase, suggesting dormant origins might be activated in response to defects in DNA replication initiation. Fission yeast Rad22 is implicated in forming nuclear foci in response to damaged DNA. By tracking YFP-labeled Rad22, I screened for potential DNA damage in rid mutants grown at semi-permissive temperatures, and the results show that DNA damage occurs as the result of defects in DNA replication initiation. I also identified camptothecin, a DNA topoisomerase I inhibitor that can at low dose (2 µM) induce the rid phenotype, suggesting our assay (Chk1-dependent, Cds1-independent) can be used to screen small molecule inhibitors that interfere with the initiation step of DNA replication.

No description available.

No description available.

Poly(p-phenylenebenzobisimidazole), PBI, is a rigid-rod polymer with a fully conjugated backbone having superior mechanical properties, thermo-oxi- dative and solvent stabilities. The stabilities cause processing difficulties and in terms limit its applications in critical technologies, such as conducting polymers, nonlinear optics, and solid polyelectrolytes. In this study, a chemical derivative of PBI, poly[1,7-dihydrobenzo[1,2- d:4,5-d¡¦]diimidazo-2,6-diyl[2-(2-sulfo)-p-phenylene]], sPBI, was synthesized by polycondensation reaction of 1,2,4,5-tetraaminobenzene tetrahydrochloride with 2-sulfoterephthalic acid in poly(phosphoric acid). Isolated sPBI was measured in 30oC methanesulfonic acid for an intrinsic viscosity as high as 10.5 dL/g. sPBI polymer was then reacted with 1,3-propanesultone in dimethylsulfoxide containing sodium hydride for water-soluble rigid-rod polyelectrolyte, poly[1,7- dipropylsulfobenzo-[1,2-d:4,5-d¡¦]diimidazo-2,6-diyl-[2,(2-sulfo)-p-phenylene]], sPBI-PS(Na+). sPBI-PS(Na+) was further converted to sPBI-PS(Li+) with hydrochloride and followed with lithium hydroxide. Various analyses were applied to ascertain chemical structure, purities and thermal properties of synthesized monomers and polymers. sPBI-PS(Li+) aqueous solutions were doped individually with lithium salts of LiI, LiBF4, and LiCF3SO3 at concentrations up to 1.7¡Ñ10-5 wt./wt., which were cast into freestanding films of 10-25 £gm in thickness. Direct-current conductivity measured at room- temperature parallel to the film surface was as large as 9.74¡Ñ10-5 S/cm. The ionic nature of the conductivity was revealed by constant-voltage depletion measurements. X-ray scattering results suggested that the cast film was in-plane isotropic but out-of-the plane anisotropic with the rigid-rod backbone lying in the plane of the film.

This diploma thesis deals with the transport of dangerous goods by rail in order to present and map this issue. Carriage of such cargo poses a threat to persons, animals, property and the environment, therefore it folllows the special rules established in the international agreement RID. The emphasis is placed on its analysis and subsequent application of acquired theoretical knowledge to a practical example of transport of dangerous flammable and toxic substances to the East European country.

No description available.

Members of the Six4/5 family of homeobox transcription factors have been implicated in multiple human disorders, including type I mytonic dystrophy, branchio-oto-renal syndrome, and holoprosencephaly, suggesting a role for these factors in the nervous system development. Using a forward genetics approach, we identified unc-39, a C. elegans homologue of the human SIX5 gene, as a novel regulator of the development of a specific neuron, called RID. Our data support the role of unc-39 early in C. elegans development and suggest a possibility of complete absence of RID neuron in unc-39 mutants. unc-39 mutant has a similar locomotion phenotype to the RID-ablated animals, which provides further support to the hypothesis that the absence of RID contributes to the locomotion phenotype observed in the mutant. We show that unc-39 functions at multiple points in the lineage that gives rise to the RID neuron, and that its function is context-dependent.

Members of the Six4/5 family of homeobox transcription factors have been implicated in multiple human disorders, including type I mytonic dystrophy, branchio-oto-renal syndrome, and holoprosencephaly, suggesting a role for these factors in the nervous system development. Using a forward genetics approach, we identified unc-39, a C. elegans homologue of the human SIX5 gene, as a novel regulator of the development of a specific neuron, called RID. Our data support the role of unc-39 early in C. elegans development and suggest a possibility of complete absence of RID neuron in unc-39 mutants. unc-39 mutant has a similar locomotion phenotype to the RID-ablated animals, which provides further support to the hypothesis that the absence of RID contributes to the locomotion phenotype observed in the mutant. We show that unc-39 functions at multiple points in the lineage that gives rise to the RID neuron, and that its function is context-dependent.

The purpose of this study was to develop an understanding of how Virginia counselors engage in social issues advocacy, specifically advocacy for Black/African American clients/students. Racial Identity (Helms, 1993) and Multicultural Social Justice Counseling Competencies (Ratts, Singh, Nassar-McMillan, Butler, and McCullough, 2016) are used as the framework. The researcher examined whether the work setting of a counselor impacts the amount and type of involvement with race-specific advocacy and how counselors are supported as advocates in that setting. Data was collected via information questionnaires including demographic and professional background, attitudes and beliefs captured by the Social Issues Advocacy Scale, and race-specific advocacy activity. The sample included Masters-holding professional counselors practicing in Virginia and who are members of professional organizations based in Virginia. Results indicate reasons for advocating, when applicable, with or on behalf of Black/African American clients/students and a relationship with workplace setting type. Findings show that counselors feel supported by their workplace to advocate on the basis of race, however the type of advocacy varies. / Ph. D.

Le sujet de cette thèse consiste à formuler et caractériser de nouveaux matériaux hybrides inorganique/organique pour la formulation et la libération de principes actifs. Ces matériaux sont constitués soit par des hydroxydes doubles lamellaires (HDL) et des phospholipides (PL) soit par des hydroxydes doubles lamellaires et du chitosane. Les matériaux hybrides hydroxydes doubles lamellaires/phospholipides ont été obtenus par échange anionique entre les anions du feuillet d'HDL et les phospholipides chargés négativement sous forme de liposomes. Les techniques d'analyse utilisées (DRX, ATG, UV et MET) ont permis de déterminer l'influence de la nature des anions de compensation des feuillets d'HDL et des phospholipides sur le taux de intercalation de PL dans les HDL et le taux de chargement d'un principe actif modèle : l'estradiol. Nous avons effectué ensuite des cinétiques de libération des phospholipides et de l'estradiol intercalés en faisant varier le pH et la composition du milieu pour déterminer les propriétés de ce matériau en tant que système de libération sous forme d'implant afin de libérer le principe actif sur des temps très longs. Les matériaux hybrides hydroxydes doubles lamellaires/chitosane ont ensuite été synthétisés sous forme de billes par un procède sol-gel nous permettant d'optimiser la morphologie et la texture des matériaux par le contrôle de la viscosité et le choix du mode de séchage (étuve ou spray-drying). Le chitosane a été choisi pour ses propriétés muco-adhésives afin d'envisager une application du matériau sur les muqueuses. Les techniques d'analyse utilisées ont permis de confirmer la présence de HDL dans le chitosane (DRX), de déterminer la morphologie des billes (MET, MEB) ainsi que leur composition (ATG). Des cinétiques de libération au cours de temps et en fonction de pH ont été réalisées sur de billes chitosane/ hydroxydes doubles lamellaires chargées en principe actif (ibuprofène ou phospholipides charge en estradiol) afin de déterminer leur potentiel de libération du PA. Ces nouveaux hybrides inorganique/organique s'avèrent donc être des matériaux très intéressants en tant que systèmes de libération contrôlée de principes actifs dans le domaine pharmaceutique. / The aim of this work involves the preparation and the characterization of new inorganic/ organic hybrids materials as drug delivery systems. These materials are composed of layered double hydroxide (LDH) and phospholipids (PL) or layered double hydroxide and chitosan. The layered double hydroxide/phospholipids hybrids materials were obtained by anionic exchange between the anions from the HDL layers and the liposome composed of phospholipids with negative charges. Different analysis were used such as XRD, TGA, TEM and fluorescence for the characterization of these materials and the determination of parameters such as the nature of the LDH anions nature, the kind of phospholipids as well the ratio of used model drug (17ƒÒ-estradiol) allowing the optimal method. Release kinetic studies of the phospholipids and of the drug were carried out in different release media (pH, nature of ions) to evaluate the potential sustained release properties of these hybrid materials. Layered double hydroxide/chitosan beads were developed by a sol-gel process. Chitosan was chosen for its muco-adhesive properties permitting to broaden the possibility of pharmaceutical applications. This method allowed us to improve the morphology and the texture of the material by controlling the viscosity and the drying process. Materials were characterized by XRD, TGA, SEM and TEM to determine: the presence of LDH, the encapsulated LDH yield and the morphology of the beads. Releases kinetic of a model drug (ibuprofen) encapsulated in layered double hydroxide/chitosan hybrid materials allowed us to test its potential release properties. Such new inorganic/ organic hybrids materials proved to be interesting as sustained release systems in pharmaceutical domain.