The role of glyceraldehyde 3-phosphate dehydrogenase (GapA-1) in <Emphasis Type="Italic">Neisseria meningitidis</Emphasis> adherence to human cells

Background  

Glyceraldehyde 3-phosphate dehydrogenases (GAPDHs) are cytoplasmic glycolytic enzymes, which although lacking identifiable secretion signals, have also been found localized to the surface of several bacteria (and some eukaryotic organisms); where in some cases they have been shown to contribute to the colonization and invasion of host tissues. Neisseria meningitidis is an obligate human nasopharyngeal commensal which can cause life-threatening infections including septicaemia and meningitis. N. meningitidis has two genes, gapA-1 and gapA-2, encoding GAPDH enzymes. GapA-1 has previously been shown to be up-regulated on bacterial contact with host epithelial cells and is accessible to antibodies on the surface of capsule-permeabilized meningococcal cells. The aims of this study were: 1) to determine whether GapA-1 was expressed across different strains of N. meningitidis; 2) to determine whether GapA-1 surface accessibility to antibodies was dependant on the presence of capsule; 3) to determine whether GapA-1 can influence the interaction of meningococci and host cells, particularly in the key stages of adhesion and invasion.     

Emotional state variations in rats during recall of passive avoidance reactions after neurotensin administration into nucleus accumbens of the brain

Behavioral effects of neurotensin administration into the nucleus accumbens were studied in rats with neurotoxic lesions of serotoninergic structures of the dorsal raphe nucleus or periaqueductal grey matter. Changes in recall of passive avoidance conditioned reactions and aftereffects of painful stimulation in the locomotor activity were studied in the "open field" and elevated plus-maze and T-maze tests. The toxin administration into the dorsal raphe nucleus did not impair the recall of the passive avoidance reactions, but enhanced the oppressive aftereffects of painful stimulation, which can specify the development of anxiety in rats. The toxin administration into the periaqueductal grey matter had an opposite effect, which can be considered as a manifestation of the panic state. Neurotensin weakened the above mentioned effects of the toxin and, depending on the evoked emotional disorders, produced the anxiolytic or antipanic effects.     

The normalization of tumor cell morphology related to an increase in their size: research on giant cells produced by mitomycin C treatment]

This study shows that artificial increase in cell site leads to morphological normalization of transformed fibroblasts. Mouse L cells (clone 171/5) were used. As most transformed cells, they were poorly spread on the substratum, made only dot-like focal contacts with it, rounded quickly at room temperature and did not contain prominent actin cables. Giant cells were obtained by incubation of these cells in the medium supplemented with mitomycin C (0.15-0.20 mcg/ml). DNA synthesis and mitosis were blocked by this treatment, while protein synthesis was changing very slightly. As a consequence, the cell size increased dramatically from 3 to 11 days of the cell incubation in the mitomycin containing medium. The degree of cell spreading per mcg of protein increased significantly in the giant cells. These cells do not round after moderate cooling, and well developed system of actin cables and matured streak-like focal contacts associated with these cables are formed in them. These results, along with our previous data on the restoration of cell spreading and cytoskeleton structure in giant multinucleated cells, provide strong evidences that the increase in cell size per se can induce qualitative changes in cell morphology. It can be suggested that there are some scaling-dependent factors regulating the processes of cytoskeleton assembly and formation of cell-substrate contacts.     

Effect of polyploidization on the anchorage-independent multiplication of transformed cells

Three nearhexaploid sublines were obtained from hypotriploid mouse L cells by means of colcemid treatment. When cultivated on solid substratum, all of them did not differ from the parental line either in doubling time or in cloning efficiency. The ability of polyploid cell variants to be initiated for proliferation in a semi-solid medium was equal to that of hypotriploid cells, while the average diameter of colonies formed by hexaploid cells in methyl cellulose turned out to be significantly smaller than the size of colonies of parental cells. The inhibition of growth in the semi-solid medium may reflect partial normalization of the transformed phenotype of polyploid L cells.     

Relation of the signs of malignant degeneration and tumor cell reaction to a growth-stimulating factor

Six clones of mouse sarcoma induced by subcutaneous implantation of a plastic film were studied. They differed in the degree of production of the transforming growth factor (TGF) and in stimulation of proliferation in semi-solid medium. The degree of cancerogenicity and cloning efficiency in semi-solid medium correlated with the reactivity of cells to TGF.     

Prevalence of human papillomavirus infection,distribution of viral types and risk factors in cervical samples from human immunodeficiency virus-positive women attending three human immunodeficiency virus-acquired immune deficiency syndrome reference centres in northeastern Brazil

Human immunodeficiency virus (HIV)-positive patients have a greater prevalence of coinfection with human papillomavirus (HPV) is of high oncogenic risk. Indeed, the presence of the virus favours intraepithelial squamous cell lesion progression and may induce cancer. The aim of this study was to evaluate the prevalence of HPV infection, distribution of HPV types and risk factors among HIV-positive patients. Cervical samples from 450 HIV-positive patients were analysed with regard to oncotic cytology, colposcopy and HPV presence and type by means of polymerase chain reaction and sequencing. The results were analysed by comparing demographic data and data relating to HPV and HIV infection. The prevalence of HPV was 47.5%. Among the HPV-positive samples, 59% included viral types of high oncogenic risk. Multivariate analysis showed an association between HPV infection and the presence of cytological alterations (p = 0.003), age greater than or equal to 35 years (p = 0.002), number of partners greater than three (p = 0.002), CD4⁺ lymphocyte count < 200/mm³ (p = 0.041) and alcohol abuse (p = 0.004). Although high-risk HPV was present in the majority of the lesions studied, the low frequency of HPV 16 (3.3%), low occurrence of cervical lesions and preserved immunological state in most of the HIV-positive patients were factors that may explain the low occurrence of precancerous cervical lesions in this population.     

Kinetics of uranous iron and ferrous iron oxidation by thiobacillus ferrooxidans

Archives of Microbiology -     

Effect of some drugs on colchicine uptake by colchicine-sensitive and resistant cells

The effect of several agents on 3H-colchicine, uptake by L cells and resistant to colcemide and colchicine L-53 cells was studied. Vinblastin to which L-53 cells are cross-resistant increases labeled colchicine uptake by L and L-53 cells 3- and 8-fold, respectively. The substances which decrease ATP level in the cells (olygomycin, etc.) enhance colchicine uptake by L and L-53 cells 2--4-fold. In the presence of these substances colchicine uptake by resistant cells is more intensive than by sensitive L cells. The structural analogue of colchicine, lumicolchicine, inactive in binding the microtubular protein tubulin enhances colchicine uptake by L and L-53 cells to about equal degree.