Ventrolateral medulla mechanisms involved in cardiorespiratory responses to central chemoreceptor activation in rats

A rise in arterial Pco(2) stimulates breathing and sympathetic activity to the heart and blood vessels. In the present study, we investigated the involvement of the retrotrapezoid nucleus (RTN) and glutamatergic mechanisms in the B?tzinger/C1 region (B?tz/C1) in these responses. Splanchnic sympathetic nerve discharge (sSND) and phrenic nerve discharge (PND) were recorded in urethane-anesthetized, sino-aortic-denervated, vagotomized, and artificially ventilated rats subjected to hypercapnia (end-expiratory CO(2) from 5% to 10%). Phrenic activity was absent at end-expiratory CO(2) of 4%, and strongly increased when end-expiratory CO(2) reached 10%. Hypercapnia also increased sSND by 103 ± 7%. Bilateral injections of the GABA-A agonist muscimol (2 mM) into the RTN eliminated the PND and blunted the sSND activation (Δ = +56 ± 8%) elicited by hypercapnia. Injections of NMDA receptor antagonist AP-5 (100 mM), non-NMDA receptor antagonist 6,7-dinitro-quinoxaline-2,3-dione (DNQX; 100 mM) or metabotropic glutamate receptor antagonist (+/-)-alpha-methyl-4-carboxyphenylglycine (MCPG; 100 mM) bilaterally into the B?tz/C1 reduced PND (Δ = +43 ± 7%, +52 ± 6% or +56 ± 11%, respectively). MCPG also reduced sSND (Δ = +41 ± 7%), whereas AP-5 and DNQX had no effect. In conclusion, the increase in sSND caused by hypercapnia depends on increased activity of the RTN and on metabotropic receptors in the B?tz/C1, whereas PND depends on increased RTN activity and both ionotropic and metabotropic receptors in the B?tz/C1.     

Effective range of reproductive interference exerted by an alien dandelion, <Emphasis Type="Italic">Taraxacum officinale</Emphasis>, on a native congener

Reproductive interference (RI), defined as the fitness cost of interspecific sexual interactions, such as interspecific pollen transfer (IPT) in plants, is ecologically important. Theoretically, RI could result in competitive exclusion, as it operates in a frequency-dependent manner. Additionally, IPT may have a greater range than resource competition, although information about the range of IPT is lacking. In the present study, we measured the range of IPT exerted by Taraxacum officinale (an alien species) on a native dandelion, T. japonicum. We used two approaches. In one, we analyzed the RI effect on a native seed set at three spatial scales. In the second, we tracked IPT from alien to native flower heads using fluorescent pigments as markers. We estimated that pollination distances were in the order of several meters. These distances exceeded the mean distance from each native plant to the nearest alien. As hypothesized, the effect of RI reached farther than neighboring individuals. These data indicate the spatial range from which alien dandelions should be removed to allow the conservation of natives.     

Discovery of new orally active prostaglandin D2 receptor antagonists

To identify an orally available drug candidate, a series of 3-benzoylaminophenylacetic acids were synthesized and evaluated as prostaglandin D(2) (PGD(2)) receptor antagonists. Some of the compounds tested were found to exhibit excellent inhibitory activity against cAMP accumulation in human platelet rich plasma (hPRP), which is one of the indexes of DP antagonism. The optimization process including improvement of the physicochemical properties such as solubility, which may result in an improved pharmacokinetic (PK) profile, is presented. Optimized compounds were studied for their pharmacokinetics and in vivo potential. A structure-activity relationship study is also presented. Some of the test compounds were found to have in vivo efficacy towards the inhibition of PGD(2)-induced and OVA-induced vascular permeability in guinea pig conjunctiva.     

Lactoferrin feeding augments peritoneal macrophage activities in mice intraperitoneally injected with inactivated Candida albicans

Oral administration of lactoferrin (LF), an innate-defense protein present in exocrine secretions such as milk and in neutrophils, is reported to improve host-protection against infections with microorganisms including pathogenic fungi, possibly due to an immunomodulatory effect. This study aimed to evaluate the effect of bovine LF feeding on peritoneal macrophage activities in mice intraperitoneally injected with inactivated Candida albicans. Time course analysis during the 14 days following Candida-priming revealed that LF administration slightly increased the number of peritoneal exudate cells, and significantly enhanced the production of superoxide anion (O2(-)) and nitric oxide (NO) by peritoneal macrophages at day 7. LF administration facilitated NO production and Candida hyphal-growth inhibition by macrophages derived from Candida-primed mice but not non-primed mice, suggesting that the action of LF is dependent on the immune status of the host. LF administration altered the kinetics of cytokines in the peritoneal lavage fluid of Candida-primed mice. Enhancement of cytokine levels by LF was observed for IL-12 at day 5 and IFN-gamma at day 9, but not for TNF-alpha or IL-10. In conclusion, LF feeding augmented the activities of macrophages in a manner dependent on Candida-priming and these effects may be related to enhanced cytokine levels.     

Cyclic AMP potentiates vascular endothelial cadherin-mediated cell-cell contact to enhance endothelial barrier function through an Epac-Rap1 signaling pathway

Cyclic AMP (cAMP) is a well-known intracellular signaling molecule improving barrier function in vascular endothelial cells. Here, we delineate a novel cAMP-triggered signal that regulates the barrier function. We found that cAMP-elevating reagents, prostacyclin and forskolin, decreased cell permeability and enhanced vascular endothelial (VE) cadherin-dependent cell adhesion. Although the decreased permeability and the increased VE-cadherin-mediated adhesion by prostacyclin and forskolin were insensitive to a specific inhibitor for cAMP-dependent protein kinase, these effects were mimicked by 8-(4-chlorophenylthio)-2'-O-methyladenosine-3', 5'-cyclic monophosphate, a specific activator for Epac, which is a novel cAMP-dependent guanine nucleotide exchange factor for Rap1. Thus, we investigated the effect of Rap1 on permeability and the VE-cadherin-mediated cell adhesion by expressing either constitutive active Rap1 or Rap1GAPII. Activation of Rap1 resulted in a decrease in permeability and enhancement of VE-cadherin-dependent cell adhesion, whereas inactivation of Rap1 had the counter effect. Furthermore, prostacyclin and forskolin induced cortical actin rearrangement in a Rap1-dependent manner. In conclusion, cAMP-Epac-Rap1 signaling promotes decreased cell permeability by enhancing VE-cadherin-mediated adhesion lined by the rearranged cortical actin.     

Degradation of Stop Codon Read-through Mutant Proteins via the Ubiquitin-Proteasome System Causes Hereditary Disorders

During translation, stop codon read-through occasionally happens when the stop codon is misread, skipped, or mutated, resulting in the production of aberrant proteins with C-terminal extension. These extended proteins are potentially deleterious, but their regulation is poorly understood. Here we show in vitro and in vivo evidence that mouse cFLIP-L with a 46-amino acid extension encoded by a read-through mutant gene is rapidly degraded by the ubiquitin-proteasome system, causing hepatocyte apoptosis during embryogenesis. The extended peptide interacts with an E3 ubiquitin ligase, TRIM21, to induce ubiquitylation of the mutant protein. In humans, 20 read-through mutations are related to hereditary disorders, and extended peptides found in human PNPO and HSD3B2 similarly destabilize these proteins, involving TRIM21 for PNPO degradation. Our findings indicate that degradation of aberrant proteins with C-terminal extension encoded by read-through mutant genes is a mechanism for loss of function resulting in hereditary disorders.     

Trophinin is a potent prognostic marker of ovarian cancer involved in platinum sensitivity

Ovarian cancer is the leading cause of death in women with gynecological malignancies, with prognosis of advanced stage tumors determined by chemotherapeutic response and the success of tumor resection. Since aberrant RAS pathway activation is frequent in ovarian cancer, study of in vitro RAS-induced transformation and accompanying genomic expression changes in ovarian surface epithelial cells is imperative for development of new therapeutic modalities and for understanding tumorigenesis. cDNA microarray analysis revealed TROPHONIN (TRO), a homophilic adhesion molecule involved in blastocyst implantation, was among the genes most downregulated by RAS induction. TRO expression is higher in cisplatin-sensitive cancer cell lines and positively correlates with prognoses in ovarian cancers. TRO knockdown by RNA interference conferred cisplatin resistance and led to increased invasiveness of cultured ovarian cancer cells. These findings underscore the importance of TRO in tumorigenesis, and suggest that TRO may be a useful biomarker for cisplatin sensitivity and invasive potential.     

Immunohistochemical characterization of cell types expressing the cellular prion protein in the small intestine of cattle and mice

The gastrointestinal tract is thought to be the main site of entry for the pathological isoform of the prion protein (PrP^Sc). Prion diseases are believed to result from a conformational change of the cellular prion protein (PrP^c) to PrP^Sc. Therefore, PrP^c expression is a prerequisite for the infection and spread of the disease to the central nervous system. However, the distribution of PrP^c in the gut is still a matter of controversy. We therefore investigated the localization of PrP^c in the bovine and murine small intestine. In cattle, most PrP^c positive epithelial cells were detected in the duodenum, while a few positive cells were found in the jejunum. PrP^c was expressed in serotonin producing cells. In bovine Peyer’s patches, PrP^c was distributed in extrafollicular areas, but not in the germinal centre of the jejunum and ileum. PrP^c was expressed in myeloid lineage cells such as myeloid dendritic cells and macrophages. In mice, PrP^c was expressed in some epithelial cells throughout the small intestine as well as in cells such as follicular dendritic cell in the germinal centre of Peyer’s patches. In this study, we demonstrate that there are a number of differences in the localization of PrP^c between the murine and bovine small intestines.