Stereospecific anomalies in the structure of five completely sequenced yeast chromosomes

Using an original computer program we analysed complete nucleotide sequences of chromosomes I, II, III, VI and IX in yeast cells. As a general rule, we found large stereospecific anomalies near genes with a presumed high expression level (a full catalogue of such anomalies for 5 genes with highest CAI in each chromosome is presented). As a rule, they are also present at mobile genetic elements. Many large stereospecific anomalies are situated next to the sites of specific anomalies of general nucleotide composition-regions devoid of specific dinucleotides. We have noticed many "trains" (lines) of different stereospecific anomalies, possibly showing areas of cooperative binding of different regulatory and structural proteins to DNA. In several, but not all, analysed chromosomes we found a new class of especially large stereospecific anomalies related to repetitive DNA of small length (less than or around 100 nucleotides).     

Changes in the biological and immunologic parameters in the oral cavity of the aged. Review

Senescence is the effect of the immune system incapacity to see "self" and "non-self"; timo-involution induced down-regulation of immunoregulatory -T and B-lymphocytes. Immunosenescence mutations in oral cavity are examined. Even the oral ecosystem presents disorders in quality and quantity of the bacterial plaque and a different immune response. Age senescence is particularly evident in the masticatory apparatus, in fact the dental tissues have remarkable morpho-structural physiological changes; the epithelial, connective and osseous tissues of the periodontium have structural age changes related to the collagen synthesis and physical properties, with an increase of the stroma and a decrease of cell population. The osseous tissue presents cellular atrophy, sclerosis, osteoporosis and is undergoing a continuous structural remodelling; the oral mucous membranes show a thinning of epithelium and an increase of the stroma related to the parenchyma. Specific individual changes could be appraised in the involution of stomatognathic apparatus, more than an indefinite reduction of the performances.     

Three-dimensional gray scale ultrasonographic imaging of the celiac axis: preliminary report

BACKGROUND AND OBJECTIVES: We have previously reported the isolation of a G protein-coupled receptor, CXCR-4, that is overexpressed in glioblastoma multiforme tumor tissue (GMTT), as compared to normal brain tissue (NBT). METHODS: Gene-specific RT-PCR, Northern blotting, and in situ hybridization techniques were used to study its expression in a variety of normal tissues, tumor tissues, and cell lines, as well as during development. Antisense CXCR-4 was overexpressed in glioblastoma cells to study its effect on cell proliferation. RESULTS: Gene-specific RT-PCR analysis indicated that the CXCR-4 gene is overexpressed in several malignant glioma tissues, breast tumor tissues and cell lines. Northern blot analysis indicated that CXCR-4 is expressed at high levels in certain leukemias, uterine cancer, and Burkitt's lymphoma cell line. The occipital and temporal lobe showed high levels of CXCR4 in normal human brain. The CXCR-4 gene was expressed in all organs in the early stages of development (days 8-10). In adult mouse, CXCR-4 is expressed only in brain, spinal cord, bone marrow, and pituitary gland. Antisense CXCR-4 overexpression in glioblastoma cells caused inhibition of cell proliferation and induction of cellular differentiation in vitro. This suggests that CXCR-4 expression may play an important role during embryonic development and also in the genesis of human gliomas. CONCLUSIONS: On the basis of CXCR4 expression data and antisense overexpression data, we conclude that CXCR-4 plays an important role in the tumorigenic properties of brain, breast, and other tumor types. On the basis of its unique expression during mouse development, we conclude that it may play an important role in the normal functioning of brain, spinal cord, and bone marrow during development.     

A simple but precise method for quantitative measurement of the quality of the laser focus in a scanning optical microscope

We report a method for characterizing the focussing laser beam exiting the objective in a laser scanning microscope. This method provides the size of the optical focus, the divergence of the beam, the ellipticity and the astigmatism. We use a microscopic‐scale knife edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide, and a light‐collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, a beam profile in the form of an error function can be obtained and by repeating this with the knife edge at different axial positions relative to the beam waist, the divergence and astigmatism of the postobjective laser beam can be obtained. The measured divergence can be used to quantify how much of the full numerical aperture of the lens is used in practice. We present data of the beam radius, beam divergence, ellipticity and astigmatism obtained with low (0.15, 0.7) and high (1.3) numerical aperture lenses and lasers commonly used in confocal and multiphoton laser scanning microscopy. Our knife‐edge method has several advantages over alternative knife‐edge methods used in microscopy including that the knife edge is easy to prepare, that the beam can be characterized also directly under a cover slip, as necessary to reduce spherical aberrations for objectives designed to be used with a cover slip, and it is suitable for use with commercial laser scanning microscopes where access to the laser beam can be limited.     

Effect of carboxyl graphene nanofluid on automobile radiator performance

Nanofluid is a promising solution for the improvement of the radiator performance. In the current research work, the effect of the nanofluid carboxyl graphene on the performance of a radiator is studied. Carboxyl graphene nanoplatelets are added to 50:50 ethylene glycol–distilled water at three concentrations of 0.02, 0.03, and 0.04 vol%. The liquid flow rate is varied from 3 liters per minute (LPM) to 6 LPM, and the inlet liquid to the radiator has been maintained at constant temperatures of 40 °C and 50 °C. The inlet air Reynolds number is varied between 1200 and 2500. The effects of these on performance parameters such as Nusselt number, effectiveness, and friction factor are investigated. It is observed that addition of carboxyl graphene nanoplatelets increases the Nusselt number and effectiveness of radiator while friction factor is unaltered. The effectiveness of radiator increases by 27.38% and 23.41% for inlet temperatures of 40 °C and 50 °C respectively at 0.02 vol% and 5 LPM flow rate.     

A caspase-9 variant missing the catalytic site is an endogenous inhibitor of apoptosis

It is likely that endogenous inhibitors of the apical caspases such as caspase-9 exist to prevent undesirable activation of caspase cascades. A naturally occurring variant of caspase-9 named caspase-9S was cloned from human liver. Caspase-9S is missing most of the large subunit of caspase-9, including the catalytic site, but has the intact prodomain and small subunit. Caspase-9S did not show apoptotic activity in transfection analysis. Overexpression of caspase-9S inhibited apoptosis induced by caspase-9, indicating that caspase-9S is an endogenous dominant-negative of caspase-9. Moreover, caspase-9S inhibited apoptosis induced by tumor necrosis factor(TNF)-alpha, TNF factor-related apoptosis-inducing ligand (TRAIL), Bax, or Fas-associated death domain-containing protein (FADD) as well as the combination of Apaf-1 and caspase-9. In vitro binding assays demonstrated that caspase-9S binds to Apaf-1 and blocks the binding of caspase-9 to Apaf-1. Coexpression of caspase-9 and caspase-9S mRNA was identified in various cell lines. Thus, caspase-9S acts as a dominant-negative inhibitor of caspase-9 activation, at least in part, by blocking Apaf-1-caspase-9 interaction.     

Response to reactive nitrogen intermediates in Mycobacterium tuberculosis: induction of the 16-kilodalton alpha-crystallin homolog by exposure to nitric oxide donors

In contrast to the apparent paucity of Mycobacterium tuberculosis response to reactive oxygen intermediates, this organism has evolved a specific response to nitric oxide challenge. Exposure of M. tuberculosis to NO donors induces the synthesis of a set of polypeptides that have been collectively termed Nox. In this work, the most prominent Nox polypeptide, Nox16, was identified by immunoblotting and by N-terminal sequencing as the alpha-crystallin-related, 16-kDa small heat shock protein, sHsp16. A panel of chemically diverse donors of nitric oxide, with the exception of nitroprusside, induced sHsp16 (Nox16). Nitroprusside, a coordination complex of Fe2+ with a nitrosonium (NO+) ion, induced a 19-kDa polypeptide (Nox19) homologous to the nonheme bacterial ferritins. We conclude that the NO response in M. tuberculosis is dominated by increased synthesis of the alpha-crystallin homolog sHsp16, previously implicated in stationary-phase processes and found in this study to be a major M. tuberculosis protein induced upon exposure to reactive nitrogen intermediates.     

Caveolin interacts with Trk A and p75(NTR) and regulates neurotrophin signaling pathways

Neurotrophins signal through Trk tyrosine kinase receptors and the low-affinity neurotrophin receptor p75(NTR). We have shown previously that activation of Trk A tyrosine kinase activity can inhibit p75(NTR)-dependent sphingomyelin hydrolysis, that caveolae are a localized site for p75(NTR) signaling, and that caveolin can directly interact with p75(NTR). The ability of caveolin to also interact with tyrosine kinase receptors and inhibit their activity led us to hypothesize that caveolin expression may modulate interactions between neurotrophin signaling pathways. PC12 cells were transfected with caveolin that was expressed efficiently and targeted to the appropriate membrane domains. Upon exposure to nerve growth factor (NGF), caveolin-PC12 cells were unable to develop extensive neuritic processes. Caveolin expression in PC12 cells was found to diminish the magnitude and duration of Trk A activation in vivo. This inhibition may be due to a direct interaction of caveolin with Trk A, because Trk A co-immunoprecipitated with caveolin from Cav-Trk A-PC12 cells, and a glutathione S-transferase-caveolin fusion protein bound to Trk A and inhibited NGF-induced autophosphorylation in vitro. Furthermore, the in vivo kinetics of the inhibition of Trk A tyrosine kinase activity by caveolin expression correlated with an increased ability of NGF to induce sphingomyelin hydrolysis through p75(NTR). In summary, our results suggest that the interaction of caveolin with neurotrophin receptors may have functional consequences in regulating signaling through p75(NTR) and Trk A in neuronal and glial cell populations.