A time course study on dose-response relationship between alcohol exposure and its effects on lipid profile and biomarkers of tissue damage

This present research investigated variations in lipid profiles and important biomarkers of tissue damage in response to graded concentrations of alcohol administration in male Wistar rats. Group A (control) received distilled water while group B, C and D received 30%, 40% and 50% (v/v) alcohol respectively. Five rats each from groups A-D were sacrificed after day(s) 1, 7, 14, 21 and 28 of administration. A significant increase was observed at day 28 for serum cholesterol by 79% (group B), 78% (group C) and 47% (group D) together with serum phospholipid 58% (group B), 50% (group C) and 92% (group D). Serum triacylglycerol increased by 71% (group B), 43% (group C) and 16% (group D) at day 21, while concentration of serum albumin decreased at day 28 by 40.9% (group B), 50.2% (group C), 53.3% (group D) respectively when compared with control (group A). Serum aminotransferases and alkaline phosphatase specific activities, as well as creatinine and uric acid concentration increased in a concentration-dependent manner, following alcohol administration. Though most of these effects induced by alcohol were time- and concentration-dependent, 40% alcohol appear to be more stable, giving results consistent with alcohol-induced damages, with minimal mortality. This study therefore further validated dyslipidemia and imbalance in clinical biomarkers as hallmarks of tissue damage induced by excessive alcohol consumption with an insight on the time- and concentration-response relationship between alcohol consumption and its toxicity.     

The sub‐nanomolar binding of DNA–RNA hybrids by the single‐chain Fv fragment of antibody S9.6

The monoclonal antibody S9.6 binds DNA–RNA hybrids with high affinity, making it useful in research and diagnostic applications, such as in microarrays and in the detection of R‐loops. A single‐chain variable fragment (scFv) of S9.6 was produced, and its affinities for various synthetic nucleic acid hybrids were measured by surface plasmon resonance (SPR). S9.6 exhibits dissociation constants of approximately 0.6 nM for DNA–RNA and, surprisingly, 2.7 nM for RNA–RNA hybrids that are AU‐rich. The affinity of the S9.6 scFv did not appear to be strongly influenced by various buffer conditions or by ionic strength below 500 mM NaCl. The smallest epitope that was strongly bound by the S9.6 scFv contained six base pairs of DNA–RNA hybrid. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

The impact of skin colour on human photobiological responses

Terrestrial solar ultraviolet radiation (UVR) exerts both beneficial and adverse effects on human skin. Epidemiological studies show a lower incidence of skin cancer in people with pigmented skins compared to fair skins. This is attributed to photoprotection by epidermal melanin, as is the poorer vitamin D status of those with darker skins. We summarize a wide range of photobiological responses across different skin colours including DNA damage and immunosuppression. Some studies show the generally modest photoprotective properties of melanin, but others show little or no effect. DNA photodamage initiates non‐melanoma skin cancer and is reduced by a factor of about 3 in pigmented skin compared with white skin. This suggests that if such a modest reduction in DNA damage can result in the significantly lower skin cancer incidence in black skin, the use of sunscreen protection might be extremely beneficial for susceptible population. Many contradictory results may be explained by protocol differences, including differences in UVR spectra and exposure protocols. We recommend that skin type comparisons be done with solar‐simulated radiation and standard erythema doses or physical doses (J/m²) rather than those based solely on clinical endpoints such as minimal erythema dose (MED).     

Yeast functional genomic screens lead to identification of a role for a bacterial effector in innate immunity regulation

Numerous bacterial pathogens manipulate host cell processes to promote infection and ultimately cause disease through the action of proteins that they directly inject into host cells. Identification of the targets and molecular mechanisms of action used by these bacterial effector proteins is critical to understanding pathogenesis. We have developed a systems biological approach using the yeast Saccharomyces cerevisiae that can expedite the identification of cellular processes targeted by bacterial effector proteins. We systematically screened the viable yeast haploid deletion strain collection for mutants hypersensitive to expression of the Shigella type III effector OspF. Statistical data mining of the results identified several cellular processes, including cell wall biogenesis, which when impaired by a deletion caused yeast to be hypersensitive to OspF expression. Microarray experiments revealed that OspF expression resulted in reversed regulation of genes regulated by the yeast cell wall integrity pathway. The yeast cell wall integrity pathway is a highly conserved mitogen-activated protein kinase (MAPK) signaling pathway, normally activated in response to cell wall perturbations. Together these results led us to hypothesize and subsequently demonstrate that OspF inhibited both yeast and mammalian MAPK signaling cascades. Furthermore, inhibition of MAPK signaling by OspF is associated with attenuation of the host innate immune response to Shigella infection in a mouse model. These studies demonstrate how yeast systems biology can facilitate functional characterization of pathogenic bacterial effector proteins.     

The N-terminal 24 amino acids of the p55 gamma regulatory subunit of phosphoinositide 3-kinase binds Rb and induces cell cycle arrest

Although phosphoinositide 3-kinase (PI 3-kinase) is essential for cell cycle progression, the molecular mechanisms that regulate its diverse biological effects are poorly understood. We demonstrate here that Rb, a key regulator of cell cycle progression, associates with p55 kDa (p55alpha and p55gamma) regulatory subunits of PI 3-kinase in vivo and in vitro. Both confocal microscopy and biochemical analysis demonstrated the presence of p55gamma in the nucleus. The 24-amino-acid N-terminal end of p55gamma, which is unique among PI 3-kinase regulatory subunits, was sufficient to bind Rb. Addition of serum or growth factors to quiescent cells triggered the dissociation of Rb from p55. Ectopic expression of the 24-amino-acid N-terminal end of p55gamma inhibited cell cycle progression, as evidenced by induction of cell growth arrest at the G0/G1 phase, inhibition of DNA synthesis, inhibition of cyclin D and cyclin E promoter activity, and changes in the expression of cell cycle-related proteins. The inhibitory effects of the N-terminal end of p55gamma on cell cycle progression depended on the presence of functional Rb. These data demonstrate for the first time an association of p55gamma with Rb and show that modification of this association can lead to cell cycle arrest.     

Estimation of linear and mass attenuation coefficients of soy–lignin bonded Rhizophora spp. particleboard as a potential phantom material using caesium-137 and cobalt-60

In this study, linear and mass attenuation coefficients of fabricated particleboards intended for use as phantom material were estimated using ¹³⁷Cs and ⁶⁰Co radiation sources. Particleboards made of Rhizophora spp. wood trunk bonded with soy flour and lignin were fabricated at a target density of 1.0 g cm^?3, with and without gloss finish coating. Elemental composition of the particleboards was obtained by means of energy dispersive X-ray (EDX) spectroscopy. Experimental setups were simulated via the GATE Monte Carlo (MC) package, with particle histories of 1?×?10⁶–1?×?10⁷. Linear and mass attenuation coefficients obtained from measurements and GATE simulations were compared and discussed. The percentage differences between the measured and simulated linear and mass attenuation coefficients of the samples were reasonably small (2.05–4.88% for ¹³⁷Cs and 3.24–5.38% for ⁶⁰Co). It is shown that all the particleboards have the potential to be used as phantom materials as the attenuation coefficients measured were in good agreement with those of water (calculated with XCOM) and with those simulated with the GATE toolkit. The use of gloss finish coating also did not show any significant effect on the attenuation coefficient of the phantom material. Verification of experimental results via GATE simulations has been shown crucial in providing reliable data for energy transmission studies. Based on the results achieved in this study, it is concluded that the studied material—Rhizophora spp. wood trunk bonded with soy flour and lignin including gloss finish coating—can be used in radiation dosimetry studies.

     

Phostoxin-induced biochemical and pathomorphological changes in rabbits

The effect of chronic phostoxin administration on some tissue ATPases, hematology and tissue histopathology was investigated using a combination of gravimetric, enzymatic, colorimetric and histological procedures in New Zealand White rabbits after 2 weeks administration of 0.8mg phostoxin/kg body weight/day, po. The phostoxin treatment led to significant decreases in Na(+)-K+ ATPase activities in renal, hepatic and cardiac tissues. Similar decreases were obtained in the activities of Ca(2+)-ATPase and Mg(2+)-ATPase in liver. In addition, the phostoxin-toxified rabbits manifested significant decreases in hematocrit, red blood cell count, hemoglobin and platelets. Histological examination of the tissues revealed pronounced degenerative changes in liver, heart and kidney.     

Tumor-induced disruption of proximal TCR-mediated signal transduction in tumor-infiltrating CD8+ lymphocytes inactivates antitumor effector phase

The presence in cancer tissue of Ag-specific, activated tumor infiltrating CD8(+) T cells proves that tumors express Ags capable of eliciting immune response. Therefore, in general, tumor escape from immune-mediated clearance is not attributable to immunological ignorance. However, tumor-infiltrating lymphocytes are defective in effector phase function, demonstrating tumor-induced immune suppression that likely underlies tumor escape. Since exocytosis of lytic granules is dependent upon TCR-mediated signal transduction, it is a reasonable contention that tumors may induce defective signal transduction in tumor infiltrating T cells. In this review, we consider the biochemical basis for antitumor T cell dysfunction, focusing on the role of inhibitory signaling receptors in restricting TCR-mediated signaling in tumor-infiltrating lymphocytes.     

Electron tomography reveals Rab6 is essential to the trafficking of trans-Golgi clathrin and COPI-coated vesicles and the maintenance of Golgi cisternal number

We have shown previously that Rab6, a small, trans-Golgi-localized GTPase, acts upstream of the conserved oligomeric Golgi complex (COG) and ZW10/RINT1 retrograde tether complexes to maintain Golgi homeostasis. In this article, we present evidence from the unbiased and high-resolution approach of electron microscopy and electron tomography that Rab6 is essential to the trans-Golgi trafficking of two morphological classes of coated vesicles; the larger corresponds to clathrin-coated vesicles and the smaller to coat protein I (COPI)-coated vesicles. On the basis of the site of coated vesicle accumulation, cisternal dilation and the normal kinetics of cargo transport from the endoplasmic reticulum (ER) to Golgi followed by delayed Golgi to cell surface transport, we suggest that Golgi function in cargo transport is preferentially inhibited at the trans-Golgi/trans-Golgi network (TGN). The >50% increase in Golgi cisternae number in Rab6-depleted HeLa cells that we observed may well be coupled to the trans-Golgi accumulation of COPI-coated vesicles; depletion of the individual Rab6 effector, myosin IIA, produced an accumulation of uncoated vesicles with if anything a decrease in cisternal number. These results are the first evidence for a Rab6-dependent protein machine affecting Golgi-proximal, coated vesicle accumulation and probably transport at the trans-Golgi and the first example of concomitant cisternal proliferation and increased Golgi stack organization under inhibited transport conditions.     

The acyclic CB1R inverse agonist taranabant mediates weight loss by increasing energy expenditure and decreasing caloric intake

Cannabinoid 1 receptor (CB1R) inverse agonists are emerging as a potential obesity therapy. However, the physiological mechanisms by which these agents modulate human energy balance are incompletely elucidated. Here, we describe a comprehensive clinical research study of taranabant, a structurally novel acyclic CB1R inverse agonist. Positron emission tomography imaging using the selective CB1R tracer [(18)F]MK-9470 confirmed central nervous system receptor occupancy levels ( approximately 10%-40%) associated with energy balance/weight-loss effects in animals. In a 12-week weight-loss study, taranabant induced statistically significant weight loss compared to placebo in obese subjects over the entire range of evaluated doses (0.5, 2, 4, and 6 mg once per day) (p < 0.001). Taranabant treatment was associated with dose-related increased incidence of clinical adverse events, including mild to moderate gastrointestinal and psychiatric effects. Mechanism-of-action studies suggest that engagement of the CB1R by taranabant leads to weight loss by reducing food intake and increasing energy expenditure and fat oxidation.