Targeting IL-15 receptor-bearing cells with an antagonist mutant IL-15/Fc protein prevents disease development and progression in murine collagen-induced arthritis

It has been suggested that the inflammatory cytokine IL-15 plays an important role in the development of several autoimmune diseases, including rheumatoid arthritis. We have generated a unique lytic and antagonistic IL-15 mutant/Fcgamma2a fusion protein (CRB-15) that targets the IL-15R. In the present study we examined the effects of targeting the IL-15R on the prevention and treatment of collagen-induced arthritis (CIA) in mice and probed the possible mechanisms of action of this IL-15 mutant/Fcgamma2a protein. Upon immunization with type II collagen, DBA/1 mice develop severe articular inflammation and destruction. Treatment of DBA/1 mice with a brief course of CRB-15 at the time of type II collagen challenge markedly inhibited the incidence and severity of arthritis. Moreover, in animals with ongoing established arthritis, treatment with CRB-15 effectively blocked disease progression compared with that in control-treated animals. The therapeutic effect of CRB-15 on either disease development or disease progression is remarkably stable, because withdrawal of treatment did not lead to disease relapse. A detailed analysis revealed that treatment with CRB-15 decreased synovitis in the joints; reduced bone erosion and cartilage destruction; reduced in situ production of the proinflammatory cytokines TNF-alpha, IL-1beta, IL-6, and IL-17; and decreased the responder frequency of autoreactive T cells. Our study suggests that the effective targeting of IL-15R-triggered events with CRB-15 can be of therapeutic importance in the treatment of rheumatoid arthritis.     

Lethal quercetin-digoxin interaction in pigs

Digoxin is a popular cardiac glycoside with very narrow therapeutic range. Quercetin is an ubiquitous antioxidant flavonoid. Digoxin is a substrate of P-glycoprotein (P-gp), a multi-drug efflux transporter, and quercetin was reported to be a modulator of P-gp. The aim of this study was to investigate the effect of quercetin on the absorption and disposition of digoxin in pigs. Pigs were orally given digoxin (0.02 mg/kg) with and without quercetin in crossover designs. The blood was collected via jugular vein and fluorescence polarization immunoassay was used to determine the serum concentration of digoxin. The pharmacokinetic parameters were calculated using WINNONLIN. The paired Student's t-test was used for statistical comparison. The coadministration of 50 mg/kg quercetin unexpectedly resulted in sudden death of two among three pigs within 30 min after digoxin administration. The coadministration of 40 mg/kg quercetin significantly elevated the C_max of digoxin by 413% and increased the AUC_0-t by 170%. The results indicated that a very serious pharmacokinetic interaction occurred between quercetin and digoxin. The concomitant administration of digoxin and quercetin or quercetin-containing herbs and dietary supplement should be avoided.     

Effects of nanomolar concentration dihydroouabain on calcium current and intracellular calcium in guinea pig ventricular myocytes

The effects of nanomolar concentration of dihydroouabain (DHO) on L-type calcium current (ICa-L), TTX-sensitive calcium current (ICa(TTX)), and intracellular calcium concentration ([Ca2+]i) were investigated in guinea pig ventricular myocytes. The whole-cell patch-clamp technique was used to record ICa-L and ICa(TTX); [Ca2+]i was detected and recorded with the confocal microscopy. The nanomolar concentration of DHO increased the ICa-L, ICa(TTX), and [Ca2+]i, which could be partially inhibited by nisoldipine or TTX, but still appeared in the absence of extracellular K+ and Na+. These data suggest that DHO could increase [Ca2+]i in non-beating myocytes via stimulating the ICa-L and ICa(TTX), or perhaps triggering directly a release of intracellular calcium.     

Chromosome painting between human and lorisiform prosimians: evidence for the HSA 7/16 synteny in the primate ancestral karyotype

Multidirectional chromosome painting with probes derived from flow-sorted chromosomes of humans (Homo sapiens, HSA, 2n = 46) and galagos (Galago moholi, GMO, 2n = 38) allowed us to map evolutionarily conserved chromosomal segments among humans, galagos, and slow lorises (Nycticebus coucang, NCO, 2n = 50). In total, the 22 human autosomal painting probes detected 40 homologous chromosomal segments in the slow loris genome. The genome of the slow loris contains 16 sytenic associations of human homologues. The ancient syntenic associations of human chromosomes such as HSA 3/21, 7/16, 12/22 (twice), and 14/15, reported in most mammalian species, were also present in the slow loris genome. Six associations (HSA 1a/19a, 2a/12a, 6a/14b, 7a/12c, 9/15b, and 10a/19b) were shared by the slow loris and galago. Five associations (HSA 1b/6b, 4a/5a, 11b/15a, 12b/19b, and 15b/16b) were unique to the slow loris. In contrast, 30 homologous chromosome segments were identified in the slow loris genome when using galago chromosome painting probes. The data showed that the karyotypic differences between these two species were mainly due to Robertsonian translocations. Reverse painting, using galago painting probes onto human chromosomes, confirmed most of the chromosome homologies between humans and galagos established previously, and documented the HSA 7/16 association in galagos, which was not reported previously. The presence of the HSA 7/16 association in the slow loris and galago suggests that the 7/16 association is an ancestral synteny for primates. Based on our results and the published homology maps between humans and other primate species, we propose an ancestral karyotype (2n = 60) for lorisiform primates.     

Cytoplasmic male sterility of rice with boro II cytoplasm is caused by a cytotoxic peptide and is restored by two related PPR motif genes via distinct modes of mRNA silencing

Cytoplasmic male sterility (CMS) and nucleus-controlled fertility restoration are widespread plant reproductive features that provide useful tools to exploit heterosis in crops. However, the molecular mechanism underlying this kind of cytoplasmic-nuclear interaction remains unclear. Here, we show in rice (Oryza sativa) with Boro II cytoplasm that an abnormal mitochondrial open reading frame, orf79, is cotranscribed with a duplicated atp6 (B-atp6) gene and encodes a cytotoxic peptide. Expression of orf79 in CMS lines and transgenic rice plants caused gametophytic male sterility. Immunoblot analysis showed that the ORF79 protein accumulates specifically in microspores. Two fertility restorer genes, Rf1a and Rf1b, were identified at the classical locus Rf-1 as members of a multigene cluster that encode pentatricopeptide repeat proteins. RF1A and RF1B are both targeted to mitochondria and can restore male fertility by blocking ORF79 production via endonucleolytic cleavage (RF1A) or degradation (RF1B) of dicistronic B-atp6/orf79 mRNA. In the presence of both restorers, RF1A was epistatic over RF1B in the mRNA processing. We have also shown that RF1A plays an additional role in promoting the editing of atp6 mRNAs, independent of its cleavage function.     

Looking for food in all the right places?

Examining a potential functional role for growth hormone secretagogue receptors in the hippocampus, Diano and colleagues (Diano et al., 2006), demonstrate novel actions of the orexigenic peptide ghrelin in hippocampal synaptic architecture, LTP, and learning and memory. These data suggest functional links between metabolic signaling and higher neural function.     

Determination of indomethacin in plasma by micellar electrokinetic chromatography with UV detection for premature infants with patent ducts arteriosus

A simple and selective micellar electrokinetic chromatography (MEKC) is described for determination of indomethacin in plasma. Plasma proteins are precipitated by acetonitrile. An aliquot of supernatant was evaporated and reconstituted with Tris buffer for MEKC analysis. The separation of indomethacin was performed at 25 degrees C using a background electrolyte consisting of Tris buffer (30 mM; pH 8.0) with 100 mM sodium octanesulfonate (SOS) as an anionic surfactant. Under this condition, a good separation with high efficiency and short analysis time is achieved. Several parameters affecting the separation of indomethacin were studied, including pH and concentrations of the Tris buffer and SOS. The linear range of the method for the determination of indomethacin was over 0.3-10.0 microg/mL; the detection limit (signal-to-noise ratio=3; injection 0.5 psi 5s) was 0.1 microg/mL. The proposed method for determination of indomethacin in premature infants with patent ducts arteriosus has been demonstrated.