Solution chemistry and cytotoxic properties of novel organogold(III) compounds

The solution behaviour of some novel organogold(III) compounds was investigated, and their cytotoxic properties evaluated against a few human tumour cell lines (A2780/S, A2780/R, MCF7, HT29 and A549). Specifically, the following compounds were considered: [Au(bipy(dmb)-H)(2,6-xylidine-H)][PF(6)] (AuXyl) and [Au(bipy(dmb)-H)(p-toluidine-H)][PF(6)] (AuTol) (in which bipy(dmb)=6-(1,1-dimethylbenzyl)-2,2'-bipyridine), [Au(py(dmb)-H)(AcO)(2)] (AuPyAcO) (in which py(dmb)=2-(1,1-dimethylbenzyl)-pyridine) and [Au(pz(Ph)-H)Cl(3)]K (AuPzCl) (in which pz(Ph)=1-phenylpyrazole). The solution chemistry of these compounds, under physiological-like conditions, was investigated through UV-vis absorption and (1)H NMR spectroscopies. Significant cytotoxic effects in vitro were observed in selected cases.     

ortho-Halogen naphthaleins as specific inhibitors of Lactobacillus casei thymidylate synthase. Conformational properties and biological activity

Thymidylate synthase (TS) (EC 2.1.1.45), an enzyme involved in the DNA synthesis of both prokaryotic and eukaryotic cells, is a potential target for the development of anticancer and antinfective agents. Recently, we described a series of phthalein and naphthalein derivatives as TS inhibitors. These compounds have structures unrelated to the folate (Non-Analogue Antifolate Inhibitors, NAAIs) and were selective for the bacterial versus the human TS (hTS). In particular, halogen-substituted molecules were the most interesting. In the present paper the halogen derivatives of variously substituted 3,3-bis(4-hydroxyphenyl)-1H,3H-naphtho[2,3-c]furan-1-one (1-5) and 3,3-bis(4-hydroxyphenyl)-1H,3H-naphtho[1,8-c,d]pyran-1-one (6-14) were synthesized to investigate the biological effect of halogen substitution on the inhibition and selectivity for the TS enzymes. Conformational properties of the naphthalein series were explored in order to highlight possible differences between molecules that show species-specific biological profile with respect to non species-specific ones. With this aim, the conformational properties of the synthesized compounds were investigated by NMR, in various solvents and at different temperatures, and by computational analysis. The apparent inhibition constants (K(i)) for Lactobacillus casei TS (LcTS) were found to range from 0.7 to 7.0 microM, with the exception of the weakly active iodo-derivatives (4, 10, 13); all] the compounds were poorly active against hTS. The di-halogenated compounds 7, 8, 14 showed the highest specificity towards LcTS, their specificity index (SI) ranging between 40 and >558. The di-halogenated 1,8-naphthalein derivatives (7-10) exhibited different conformational properties with respect to the tetra-haloderivatives. Though a clear explanation for the observed specificity by means of conformational analysis is difficult to find, some interesting conformational effects are discussed in the context of selective recognition of the compounds investigated by the LcTS enzyme.     

Sex determination of buffalo embryos (Bubalus bubalis) by polymerase chain reaction

The aim of this study was to identify a simple, rapid method for sex determination of in vitro produced buffalo embryos, amplifying Y-chromosome-specific repeat sequences by polymerase chain reaction (PCR). Buffalo oocytes collected from slaughtered animals were matured, fertilised and cultured in vitro for 7 days. On day 7 embryos were evaluated and divided in to six groups according to developmental stage (2, 4, 8, 16 cells, morulae and blastocyst). Each embryo was stored singly in phosphate-buffered saline at -20 degrees C until PCR. Two different methods of extraction of DNA were compared: a standard procedure (ST), using a normal extraction by phenol-chloroform, isoamyl alcohol and final precipitation in absolute ethanol and a direct procedure (DT), using a commercial kit (Qiaquik-Qiagen mini blood). A pair of bovine satellite primers and two pairs of different bovine Y-chromosome-specific primers (BRY4.a and BRY.1) were used in the PCR assay on embryos and on whole blood samples collected from male and female adult buffaloes, used as control. The trial was carried out on 359 embryos (193 for ST and 166 for DT). When DNA samples from blood were amplified, the sex determined by PCR always corresponded to the anatomical sex. Embryo sexing was not possible in two embryos in ST and one embryo in DT. Both extraction protocols recovered sufficient quantities of target DNA at all developmental stages, but the time required for the ST (24 h) limits its use in embryo sexing and supports the use of commercial extraction kits (5 h).     

Immunoglobulins against gp273, the ligand for sperm-egg interaction in the mollusc bivalve Unio elongatulus,are directed against charged O-linked oligosaccharide chains bearing a Lewis-like structure and interact with epitopes of the human zona pellucida

In oocytes of the mollusc bivalve Unio elongatulus, gp273 is the ligand molecule for sperm-egg interaction and binding is mediated by its O-glycans. A serum raised against this protein enabled its localization in the crater region, the area of the vitelline coat where sperm recognition occurs, and showed that after cyanogen bromide fragmentation, the anti-gp273 epitope(s) was retained by a peptide where the O-glycans are localized. In this article, we utilized purified anti-gp273 immunoglobulins to characterize the corresponding epitope by: (i) immunoblotting analysis of the protein after removal of O- and N-glycans; (ii) solid phase binding analysis of anti-gp273 IgG to gp273 N- and O-glycans; and (iii) binding analysis of the same antibody to commercially available oligosaccharides. The results showed that the epitope consists of O-glycans and contains a Lewis-like structure with fucose as determinant. Anti-gp273 IgG were then used to investigate human zona pellucida by immunoelectronmicroscopy and immunoblotting. Epitopes recognized by the antibody were demonstrated on the outer surface of the zona pellucida and shown to belong to a zona pellucida protein having electrophoretic mobility similar to human ZP3. Since human sperm specifically bind to gp273, and anti-gp273 interferes with this binding a functional role for these epitopes is suggested.     

Beta 2-microglobulin-free HLA class I heavy chain epitope mimicry by monoclonal antibody HC-10-specific peptide

mAb HC-10 loses its reactivity with HLA class I (HLA-I) H chain (HC) following its association with beta(2)-microglobulin (beta(2)m). Furthermore, the HC-10 defined epitope appears to be involved in the pathogenesis of spondyloarthropathies, because HC-10 reduced their incidence in HLA-B27(+)beta(2)m degrees /MHC class II knockout mice. This study has characterized the determinant recognized by HC-10. Panning of a phage display peptide library with HC-10 resulted in isolation of the motif PxxWDR, which could be aligned with P57, W60, D61, and R62 of the first domain of the HLA-I HC allospecificities reactive with HC-10. The (55)EGPEYWDR(N/E)T(64) (p-1) is the shortest motif-bearing peptide that reacts with HC-10 and inhibits its binding to soluble HLA-B7 HC, irrespective of whether N (p-1a) or E (p-1b) is present at position 63. By contrast, HC-10 did not react with six additional peptides, each bearing motif amino acid substitutions present in HC-10-not-reactive HLA-I allospecificities. The p-1-derived Qp-1, synthesized with the additional conserved Q54, which displays the highest in vitro reactivity with HC-10, was the only one to induce in mice IgG resembling HC-10 in their fine specificity. Mapping of the HC-10-defined determinant suggests that the lack of mAb reactivity with beta(2)m-associated HLA-I HC is caused by blocking by the peptide in the groove of beta(2)m-associated HLA-I HC, though a role of HC conformational changes following its association with beta(2)m cannot be excluded. This information contributes to our understanding of the molecular basis of the antigenic profiles of beta(2)m-free and beta(2)m-associated HLA-I HC and may serve to develop active specific immunotherapy of spondyloarthropathies.     

Support for association of schizophrenia with genetic variation in the 6p22.3 gene,dysbindin, in sib-pair families with linkage and in an additional sample of triad families

Genetic variants in a gene on 6p22.3, dysbindin, have been shown recently to be associated with schizophrenia (Straub et al. 2002a). There is no doubt that replication in other independent samples would enhance the significance of this finding considerably. Since the gene is located in the center of the linkage peak on chromosome 6p that we reported earlier, we decided to test six of the most positive DNA polymorphisms in a sib-pair sample and in an independently ascertained sample of triads comprising 203 families, including the families for which we detected linkage on chromosome 6p. Evidence for association was observed in the two samples separately as well as in the combined sample (P=.00068 for SNP rs760761). Multilocus haplotype analysis increased the significance further to .00002 for a two-locus haplotype and to .00001 for a three-locus haplotype. Estimation of frequencies for six-locus haplotypes revealed one common haplotype with a frequency of 73.4% in transmitted, and only 57.6% in nontransmitted, parental haplotypes. All other six-locus haplotypes occurring at a frequency of >1% were less often transmitted than nontransmitted. Our results represent a first successful replication of linkage disequilibrium in psychiatric genetics detected in a region with previous evidence of linkage and will encourage the search for causes of schizophrenia by the genetic approach.     

Exposure of yeast cells to anoxia induces transient oxidative stress. Implications for the induction of hypoxic genes

The mitochondrial respiratory chain is required for the induction of some yeast hypoxic nuclear genes. Because the respiratory chain produces reactive oxygen species (ROS), which can mediate intracellular signal cascades, we addressed the possibility that ROS are involved in hypoxic gene induction. Recent studies with mammalian cells have produced conflicting results concerning this question. These studies have relied almost exclusively on fluorescent dyes to measure ROS levels. Insofar as ROS are very reactive and inherently unstable, a more reliable method for measuring changes in their intracellular levels is to measure their damage (e.g. the accumulation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA, and oxidative protein carbonylation) or to measure the expression of an oxidative stress-induced gene, e.g. SOD1. Here we used these approaches as well as a fluorescent dye, carboxy-H(2)-dichloro-dihydrofluorescein diacetate (carboxy-H(2)-DCFDA), to determine whether ROS levels change in yeast cells exposed to anoxia. These studies reveal that the level of mitochondrial and cytosolic protein carbonylation, the level of 8-OH-dG in mitochondrial and nuclear DNA, and the expression of SOD1 all increase transiently during a shift to anoxia. These studies also reveal that carboxy-H(2)-DCFDA is an unreliable reporter of ROS levels in yeast cells shifted to anoxia. By using two-dimensional electrophoresis and mass spectrometry (matrix-assisted laser desorption ionization time-of-flight), we have found that specific proteins become carbonylated during a shift to anoxia and that some of these proteins are the same proteins that become carbonylated during peroxidative stress. The mitochondrial respiratory chain is responsible for much of this carbonylation. Together, these findings indicate that yeast cells exposed to anoxia experience transient oxidative stress and raise the possibility that this initiates the induction of hypoxic genes.