Modulation of neurotransmitter release by NO is altered in mesenteric arterial bed of spontaneously hypertensive rats

Nitric oxide (NO) reacts with catecholamines resulting in their deactivation. In the present study with the use of the perfused mesenteric arterial bed as a model of the sympathetic neuroeffector junction, the NO synthase (NOS) inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME) resulted in the enhancement of the periarterial nerve stimulation-induced increase in perfusion pressure and norepinephrine overflow while decreasing neuropeptide Y (NPY) overflow. These changes were prevented by l-arginine, demonstrating that the effects of l-NAME were specific to the inhibition of NOS. From the fact that norepinephrine acts on prejunctional alpha(2)-adrenoceptors to inhibit the evoked release of sympathetic cotransmitters, we carried out experiments in the presence of the alpha(2)-adrenergic receptor antagonist yohimbine to investigate the possibility that the decrease in NPY observed in the presence of l-NAME was due to the increase in bioactive norepinephrine acting on its autoreceptor. Periarterial nerve stimulation in the presence of both l-NAME and yohimbine prevented the previously observed decrease in NPY, indicating that the cause of this decrease was, as predicted, due to alpha(2)-adrenoceptor activation. The periarterial nerve stimulation-induced increase of norepinephrine overflow was greater in the spontaneously hypertensive rat compared with normotensive rats. In contrast to what was observed in the isolated perfused mesenteric arterial bed obtained from normotensive animals, inhibition of NOS did not result in a further increase in the overflow of norepinephrine or in a subsequent decrease in NPY. These results demonstrate that, in addition to being a direct vasodilator, NO, by deactivating norepinephrine, can modulate sympathetic neurotransmission and that this modulation is altered in the spontaneously hypertensive rat.     

Required parental investment and mating patterns: a quantitative analysis in the context of evolutionarily stable strategies

Much social psychological research has been dedicated to understanding mating strategies from the standpoint of genetic-fitness payout (e.g., Simpson and Gangestad, 2000). The current work is designed to provide a coherent, quantitative model for predicting different classes of mating strategies in both males and females. Specifically, the framework developed in this paper is an elaboration of Dawkins' (1989) quantitative assessment of different male and female mating strategies. Dawkins suggests that the prevalence of different strategies employed should be predictable in terms of evolutionary stable strategies. In the current work, a quantitative analysis predicting the prevalence of different mating strategies within each sex was conducted. The mathematical functions derived suggest that variability in the costs associated with raising offspring affects the expected prevalence of mating strategies differently for males and females. According to the present model, variability in female strategies should be less affected by changes in parental investment (PI) than variability in male strategies. Important predictions regarding male and female mating strategies across cultures are discussed.     

A DNA-based assay identifies Batrachochytrium dendrobatidis in amphibians

Chytridiomycosis caused by Batrachochytrium dendrobatidis (Chytridiomycota) has been implicated in declines of amphibian populations on four continents. We have developed a sensitive and specific polymerase chain reaction-based assay to detect this pathogen. We isolated B. dendrobatidis from captive and wild amphibians collected across North America and sequenced the internal transcribed spacer regions of the rDNA cassette of multiple isolates. We identified two primers (Bd1a and Bd2a) that are specific to B. dendrobatidis under amplification conditions described in this study. DNA amplification with Bd1a/Bd2a primers produced a fragment of approximately 300 bp from B. dendrobatidis DNA but not from DNA of other species of chytrids or common soil fungi. The assay detected 10 zoospores or 10 pg of DNA from B. dendrobatidis and detected infections in skin samples from a tiger salamander (Ambystoma tigrinum), boreal toads (Bufo boreas), Wyoming toads (Bufo baxteri), and smooth-sided toads (Bufo guttatus). This assay required only small samples of skin and can be used to process a large number of samples.     

Geomicrobiology of high-level nuclear waste-contaminated vadose sediments at the hanford site, washington state

Sediments from a high-level nuclear waste plume were collected as part of investigations to evaluate the potential fate and migration of contaminants in the subsurface. The plume originated from a leak that occurred in 1962 from a waste tank consisting of high concentrations of alkali, nitrate, aluminate, Cr(VI), (137)Cs, and (99)Tc. Investigations were initiated to determine the distribution of viable microorganisms in the vadose sediment samples, probe the phylogeny of cultivated and uncultivated members, and evaluate the ability of the cultivated organisms to survive acute doses of ionizing radiation. The populations of viable aerobic heterotrophic bacteria were generally low, from below detection to approximately 10(4) CFU g(-1), but viable microorganisms were recovered from 11 of 16 samples, including several of the most radioactive ones (e.g., >10 microCi of (137)Cs/g). The isolates from the contaminated sediments and clone libraries from sediment DNA extracts were dominated by members related to known gram-positive bacteria. Gram-positive bacteria most closely related to Arthrobacter species were the most common isolates among all samples, but other phyla high in G+C content were also represented, including Rhodococcus and Nocardia. Two isolates from the second-most radioactive sample (>20 microCi of (137)Cs g(-1)) were closely related to Deinococcus radiodurans and were able to survive acute doses of ionizing radiation approaching 20 kGy. Many of the gram-positive isolates were resistant to lower levels of gamma radiation. These results demonstrate that gram-positive bacteria, predominantly from phyla high in G+C content, are indigenous to Hanford vadose sediments and that some are effective at surviving the extreme physical and chemical stress associated with radioactive waste.     

Green tea polyphenol (-)-epigallocatechin gallate blocks epithelial barrier dysfunction provoked by IFN-gamma but not by IL-4

A characteristic of many enteropathies is increased epithelial permeability, a potentially pathophysiological event that can be evoked by T helper (Th)-1 (i.e., IFN-gamma) and Th2 (i.e., IL-4) cytokines and bacterial infection [e.g., enteropathogenic Escherichia coli (EPEC)]. The green tea polyphenol (-)-epigallocatechin gallate (EGCG) has immunosuppressive properties, and we hypothesized that it would ameliorate the increased epithelial permeability induced by IFN-gamma, IL-4, and/or EPEC. EGCG, but not the related epigallocatechin, completely prevented the increase in epithelial (i.e., T84 cell monolayer) permeability caused by IFN-gamma exposure as gauged by transepithelial resistance and horseradish peroxidase flux; EGCG did not alleviate the barrier disruption induced by IL-4 or EPEC. IFN-gamma-treated T84 and THP-1 (monocytic cell line) cells displayed STAT1 activation (tyrosine phosphorylation on Western blot analysis, DNA binding on EMSA) and upregulation of interferon response factor-1 mRNA, a STAT1-dependent gene. All three events were inhibited by EGCG pretreatment. Aurintricarboxylic acid also blocked IFN-gamma-induced STAT1 activation, but it did not prevent the increase in epithelial permeability. Additionally, pharmacological blockade of MAPK signaling did not affect IFN-gamma-induced epithelial barrier dysfunction. Thus, as a potential adjunct anti-inflammatory agent, EGCG can block STAT1-dependent events in gut epithelia and monocytes and prevent IFN-gamma-induced increased epithelial permeability. The latter event is both a STAT1- and MAPK-independent event.     

A second human antiretroviral factor, APOBEC3F, is suppressed by the HIV-1 and HIV-2 Vif proteins

The HIV-1 Vif protein suppresses the inhibition of viral replication caused by the human antiretroviral factor APOBEC3G. As a result, HIV-1 mutants that do not express the Vif protein are replication incompetent in 'nonpermissive' cells, such as primary T cells and the T-cell line CEM, that express APOBEC3G. In contrast, Vif-defective HIV-1 replicates effectively in 'permissive' cell lines, such as a derivative of CEM termed CEM-SS, that do not express APOBEC3G. Here, we show that a second human protein, APOBEC3F, is also specifically packaged into HIV-1 virions and inhibits their infectivity. APOBEC3F binds the HIV-1 Vif protein specifically and Vif suppresses both the inhibition of virus infectivity caused by APOBEC3F and virion incorporation of APOBEC3F. Surprisingly, APOBEC3F and APOBEC3G are extensively coexpressed in nonpermissive human cells, including primary lymphocytes and the cell line CEM, where they form heterodimers. In contrast, both genes are quiescent in the permissive CEM derivative CEM-SS. Together, these data argue that HIV-1 Vif has evolved to suppress at least two distinct but related human antiretroviral DNA-editing enzymes.     

Synthesis and biological activity of some structural modifications of pancratistatin

Structurally modified derivatives of 7-deoxypancratistatin have been synthesized and evaluated in cancer cell line inhibition studies.     

Aminoimidazo[1,2-a]pyridines as a new structural class of cyclin-dependent kinase inhibitors. Part 1: Design, synthesis, and biological evaluation

We have identified a novel structural class of protein serine/threonine kinase inhibitors comprised of an aminoimidazo[1,2-a]pyridine nucleus. Compounds from this family are shown to potently inhibit cyclin-dependent kinases by competing with ATP for binding to a catalytic subunit of the protein. Structure-based design approach was used to direct this chemical scaffold toward generating potent and selective CDK2 inhibitors. The discovery of this new class of ATP-site directed protein kinase inhibitors, aminoimidazo[1,2-a]pyridines, provides the basis of new medicinal chemistry tool in search for an effective treatment of cancer and other diseases that involve protein kinase signaling pathways.     

New fatty acid oxidation inhibitors with increased potency lacking adverse metabolic and electrophysiological properties

New inhibitors of palmitoylCoA oxidation were synthesized based on a structurally novel lead, CVT-3501 (1). Investigation of structure-activity relationships was conducted with respect to potency of inhibition of cardiac mitochondrial palmitoylCoA oxidation and metabolic stability. Potent and metabolically stable analogues 33, 42, and 43 were evaluated in vitro for cytochrome P450 inhibition and potentially adverse electrophysiological effects. Compound 33 was also found to have favorable pharmacokinetic properties in rat.