No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Canine Hemophagocytic Histiocytic Sarcoma (CHHS) is an aggressive neoplasm of macrophages with local lymphocytic reaction. Similarities exist between CHHS and Familial Hemophagocytic Lymphohistiocytosis (FHL), a complex of histiocytic diseases in children, which is attributable to various defects in granule dependent killing (GDK). This led to the hypothesis that defective GDK compromises lymphocyte homeostasis and anti-tumor immunity which results in CHHS. The sequence of canine perforin, a key effector molecule of GDK, was determined by RT-PCR and RACE. Genomic DNA from healthy and CHHS-affected dogs was sequenced and analyzed, but mutations with functional implications were not identified. Subsequently, tumor infiltrating lymphocytes (TIL) of CHHS were examined for GDK functionality. CHHS-TIL were compared to their functional counterparts in canine cutaneous histiocytoma (CCH), a benign histiocytic tumor in dogs, known to regress via lymphocytic reaction. To facilitate such comparison, functionality of CCH-TIL was studied by immunohistochemistry and confocal microscopy and quantified by image analysis applications. This provided novel insights regarding the physiology of TIL in tumor microenvironment and further characterizing CCH as a model for anti-tumor immunity. The comparison revealed a clear, and highly significant structural difference in polarization and degranulation of CHHS-TIL which likely hampers GDK. This defect is similar to several variants of FHL, an association further supported by comparison of clinical and laboratory manifestations of CHHS and FHL. This study suggests that CHHS is a promising natural model for investigating the pathogenesis of FHL, for studying granule polarization and degranulation and assessing the role of TIL in anti-cancer immunity. / Pet Trust foundation

NK cells control viral replication through cytotoxicity and IFNγ production. These functions were assessed in chronic HCV infected patients undergoing treatment. Aboriginals have genetic polymorphisms that may enhance NK cell function suggesting more effective clearance of chronic HCV than Caucasians. NK cell function was similar at baseline between ethnicities. At 3 months of treatment, Caucasian had higher NK killing potential compared to Aboriginal patients. This had no effect on treatment outcomes. NK cell cytotoxicity negatively correlated with viral loads while NK IFNγ production, particularly within the CD56bright subset, positively correlated with viral load suggesting that viral loads control NK cells function through an unknown mechanism. NK cell killing reflect fibrosis, but not liver damage measured by liver enzymes. IFNγ production,by NK cells does not reflect fibrosis nor liver enzymes levels. Lastly, NK cell function does not associate with therapeutic outcomes of chronic HCV infection suggesting that they do not directly play a role in therapeutic clearance of HCV.

No description available.

NK cells control viral replication through cytotoxicity and IFNγ production. These functions were assessed in chronic HCV infected patients undergoing treatment. Aboriginals have genetic polymorphisms that may enhance NK cell function suggesting more effective clearance of chronic HCV than Caucasians. NK cell function was similar at baseline between ethnicities. At 3 months of treatment, Caucasian had higher NK killing potential compared to Aboriginal patients. This had no effect on treatment outcomes. NK cell cytotoxicity negatively correlated with viral loads while NK IFNγ production, particularly within the CD56bright subset, positively correlated with viral load suggesting that viral loads control NK cells function through an unknown mechanism. NK cell killing reflect fibrosis, but not liver damage measured by liver enzymes. IFNγ production,by NK cells does not reflect fibrosis nor liver enzymes levels. Lastly, NK cell function does not associate with therapeutic outcomes of chronic HCV infection suggesting that they do not directly play a role in therapeutic clearance of HCV.

This thesis presents data exploiting one of the important chemico-biological characteristics of the transition metal iron: its ability to exist in two oxidation states. Manipulation of the reactivity of iron by ligands has been reflected by the oxygen utilisation or the amount of ferrozine-detectable Fe2+. Ligand-dependent cell associated iron has been demonstrated by prussian blue staining and ferrozinedetectable iron. Iron/8-hydroxyquinoline enters the cell by diffusion, whereas iron dextran is endocytosed as is evident from extensive vesicular staining. The involvement of iron in the cytotoxicity of H202 has been examined (a) indirectly by introduction of reducing agents which restore the cytotoxicity of H202 at 4°C (an effect which is abolished by desferrioxamine) and (b) directly by extracellularly added iron, which enhances the cytotoxicity if the iron is internalised but protects the cell if the iron remains extracellular. Cytotoxicity has been estimated by plating efficiency and by a modified tritiated thymidine incorporation assay permitting a 24 hour delay before exposure to the label. Direct free radical interaction with a ligand itself is exemplified by the production of the nitroxide free radical in desferrioxamine. This causes extensive damage to yeast alcohol dehydrogenase but can be protected by ascorbate, methionine and iron/EDTA but not iron dextran. The findings lend further support for the suggestion that free radical generation by the Fenton reaction enhances the potential cytotoxic effect of H202 provided the reactions occur at critical sites within the cell.

Cytotoxic T lymphocytes play an important role in mediating host immune reactions to viruses and other pathogens. Selective mechanisms operate during V(D)J recombination to enhance the diversity of the T cell repertoire that is generated, particularly in the CDR3 regions of the TCR, which mediate peptide recognition. The influence of V gene 3' sequences on the composition of the CDR3 loop in TCR β chains is analysed; in particular, A/T-rich coding termini are shown to be more susceptible to exonuclease "nibbling" during recombination. The recent development of peptide-MHC tetrameric complexes has enabled us to detect T lymphocytes according to their antigen specificity. Their use in detection and characterisation of EBV-specific CD8⁺ T cells during the primary acute phase of infection is described here. In particular, CTL responses to EBV lytic cycle antigens have only recently been reported and this study reveals unexpectedly high frequencies of activated, circulating CD8⁺ T lymphocytes which are directed towards lytic cycle epitopes, compared to well-characterised latent cycle antigens. In a second cohort of healthy long term asymptomatic donors, the frequency of CD8⁺ T cells recognising EBV lytic and latent cycle antigens was analysed by tetramer staining, ELISpot assays and limiting dilution assays; the tetramers detected antigen-specific CD8⁺ T lymphocytes with greater efficiency than other methods. Lytic cycle antigen-specific T lymphocytes were clearly detectable in all the asymptomatic donors, at higher frequencies than those specific for latent antigens. The final section of this thesis investigates the existence of enriched populations of EBV-specific T lymphocytes found within synovial joint fluid of rheumatoid arthritis patients. Although these cells do not appear to be directly involved in the initiation of disease, their ability to secrete proinflammatory cytokines within joints probably contributes to the maintenance of chronic inflammation in these patients.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 358-379). Also available via the Internet.

This thesis, which is divided into four chapters, represents an account on the isolation, identification and the assessment of bioactivity of cytotoxic compounds from the genus Centaurea (Family: Asteraceae alto Compositae), a large genus of about 500 species. The first three chapters deal with an introduction of natural products and Centaurea species, followed by the isolation and characterisation of compounds from twelve Centaurea species. The last chapter describes the bioactivities of extracts and isolated compounds from these species. A total of 45 compounds were isolated from twelve Centaurea species, and only C. americana, C. cyanus, C. dealbata and C. macrocephala had previously been studied. Four of these are novel compounds. Four lignans arctiin, matairesinoside, matairesinol and lappaol A were isolated fromthe methanol extract of C. macrocephala seeds. Arctiin and matairesinoside were also isolated from the methanol extract of C. americana, C. bornmuel/eri, C. dealbata, C. huber-morathii, C. mucronifera, C. pamphylica, C. schischkinii and C. urvillei. The methanol extract of C. americana also afforded 20-hydroxyecdysone, 24-hydroxyecdysone, lappaol A, arctigenin and a novel compound, 3"-O-caffeoyl(9"'→3")-arctiin. The methanol extract of C. cyanus produced lariciresinol 4-0-B-D-glucoside, berchemol, moschamine and cis-moschamine. Arctigenin, astragalin, afzelin, matairesinol and a novel indole alkaloids, schischkiniin, were isolated from the methanol extract of C. schischkinii. Extract from C. bornmuelleri afforded arctigenin, astragalin, afzelin and matairesinol. The methanol extract of C. mon/ana yielded berchemol, berchemol 4'-O-B-D-glucoside, p-coumaroylquinic acid, cis-pcoumaroylquinic acid, pinoresinol, pinoresinol mono methyl ether, pinoresinol dimethyl ether, pinoresinol 4-0-B-D-glucoside, pinoresinol 4,4'di-0-B-D-glucoside, pinoresinol 4-0-apiose-(1→2)-B-D-glucoside, centcyamine, cis-centcyamine, N-(4-hydroxycinnamoyl)-5-hydroxytryptamine, cis-N-(4-hydroxycinnamoyl)-5-hydroxytryptamine, moschamine, cis-moschamine, tryptamine and two novel compounds, flavanone-apiose-glucuronic acid and montamine. C. gigantea afforded arctiopicrin, 8-0-(4-hydroxy-3-methylbutanoyl)-salonitenolide, chlorogenic acid, cirsiliol, isoquercetrin, orientin, isoorientin and 4"-hydroxybenzoyl-isoorientin. General toxicity, cytotoxicity and antioxidant activity of the extracts and isolated compounds were evaluated, respectively, by the brine shrimp lethality assay, MTT assay on human colon cancer cell line (CaCo-2) and DPPH assay. Among all the species, the methanol extract of C. bornmuelleri, C. gigantea, C. huber-morathii and C. montana were the most toxic extracts in brine shrimp lethality and MTT assay. Arctigenin (IC50=7.0 mM), matairesinol, montamine (IC50=43.9 mM) and lappol A, schischkiniin, arctiopicrin (IC50=8.5 mM) and 8-0-(4-hydroxy-3-methylbutanoyl)-salonitenolide (IC50=26.4 mM) showed higher cytotoxicity against MTT assay. Matairesinoside (IC50=2.2 x 10-3 mg/mL), matairesinol (IC50=2.0 x 10-3 mg/mL) and schischkiniin (lC50=3.8 x 10-3 mg/mL) exhibited significant free radical scavenging activities towards DPPH assay.