Is sympathetic neurotransmission in the rat mesentery modulated by prejunctional beta adrenoceptors?

The influence of prejunctional beta adrenoceptors on neurotransmitter overflow from the sympathetic nerve terminals of the normotensive rat mesentery was investigated. The mesenteric vascular bed was isolated and perfused with Krebs-bicarbonate buffer containing phentolamine (10 microM), cocaine (10 microM) and corticosterone (40 microM). Periarterial nerve stimulation (2 Hz, 120 pulses) was performed at 8-min intervals. The influence of isoproterenol (ISO) on the stimulus-induced fractional overflow of norepinephrine (S-I OFLO) was determined by generating concentration-effect curves (0.1-1000 nM, 3- or 6.5-min exposure to each concentration). ISO did not significantly increase S-I OFLO at any concentration. On the contrary, there was a decrease in S-I OFLO at the highest concentration of ISO (1 microM). The time course of the actions of ISO was studied by utilizing single concentrations of ISO (10 nM or 1 microM, 6.5-min exposure). The presence of ISO did not significantly affect S-I OFLO at either concentration. However, S-I OFLO was decreased during stimulation periods after the removal of ISO (1 microM) from the perfusate. This inhibition was significantly attenuated by propranolol (1 microM). Pretreatment with the cyclooxygenase inhibitor indomethacin (2.8 microM) had no effect on the response to ISO or the inhibition observed after ISO removal. This inhibition remained sensitive to blockade by propranolol. Salbutamol (100 nM, 6.5-min exposure), a preferential beta 2 adrenoceptor agonist, did not facilitate or inhibit S-I OFLO. These data suggest that facilitatory prejunctional beta adrenoceptors are either not present or weakly coupled to their effector system in the normotensive rat mesentery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glyphosate is an inhibitor of plant cytochrome P450: functional expression of Thlaspi arvensae cytochrome P45071B1/reductase fusion protein in Escherichia coli

Radiofrequency (RF) energy has many advantages in thermal tumor ablation protocols. With the recent development of open MRI systems, interventional MRI procedures, including thermal ablation, have become the focus of great research interest. However, the significant interference between RF generators and MR imagers has prevented simultaneous imaging and RF ablation and, until now, has limited the role of RF-based thermal therapy in interventional MRI. Here, a simple switching circuit designed with consideration of patient safety provides compatibility between open MRI systems and RF thermal lesion generators. The experimental results show that the switching circuit allows imaging during RF ablation and opens new opportunity for MR-guided thermal therapy.     

Analysis of risk to children participating in a sociometric task.

Fourth and 5th graders (N?=?119) were individually interviewed regarding their reactions to completing group-administered, positive and negative peer nomination techniques. Results were consistent with previous findings of no obvious harm; but, additional, unique information regarding children's discussions was identified. For example, 7 children reported that 6 low-status peers were talked about behind their backs. However, these 7 children further reported that, to the best of their knowledge, none of the 6 low-status peers found out about the negative comments. No child reported having hurt feelings or having knowledge of anyone else having hurt feelings. Overall, 17% of the children (n?=?20) reported that they were complimented by others; high-status peers were significantly more likely to be complimented. It was determined that the condition of minimal risk of harm, harm not greater than children might encounter in daily life, was not breached. Directions for further research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evolution of internal eliminated segments and scrambling in the micronuclear gene encoding DNA polymerase alpha in two Oxytricha species

To learn about the evolution of internal eliminated segments (IESs) and gene scrambling in hypotrichous ciliates we determined the structure of the micronuclear (germline) gene encoding DNA polymerasealpha(DNA polalpha) in Oxytricha trifallax and compared it to the previously published structure of the germline DNA polalphagene in Oxytricha nova . The DNA polalphagene of O.trifallax contains 51 macronuclear-destined segments (MDSs) separated by 50 IESs, compared to 45 MDSs and 44 IESs in the O.nova gene. This means that IESs and MDSs have been gained and/or lost during evolutionary divergence of the two species. Most of the MDSs are highly scrambled in a similar non-random pattern in the two species. We present a model to explain how IESs, non-scrambled MDSs and scrambled MDSs may be added and/or eliminated during evolution. Corresponding IESs in the two species differ totally in sequence, and junctions between MDSs and IESs are shifted by 1-18 bp in O.trifallax compared to the O.nova gene. In both species a short region of the gene is distantly separated from the main part of the gene. Comparison of the gene in the two species shows that IESs and scrambling are highly malleable over evolutionary time.     

Y chromosome polymorphisms in native American and Siberian populations: identification of native American Y chromosome haplotypes

We have initiated a study of ancient male migrations from Siberia to the Americas using Y chromosome polymorphisms. The first polymorphism examined, a C-->T transition at nucleotide position 181 of the DYS199 locus, was previously reported only in Native American populations. To investigate the origin of this DYS199 polymorphism, we screened Y chromosomes from a number of Siberian, Asian, and Native American populations for this and other markers. This survey detected the T allele in all five Native American populations studied at an average frequency of 61%, and in two of nine native Siberian populations, the Siberian Eskimo (21%) and the Chukchi (17%). This finding suggested that the DYS199 T allele may have originated in Beringia and was then spread throughout the New World by the founding populations of the major subgroups of modern Native Americans. We further characterized Native American Y chromosome variation by analyzing two additional Y chromosome polymorphisms, the DYS287 Y Alu polymorphic (YAP) element insertion and a YAP-associated A-->G transition at DYS271, both commonly found in Africans. We found neither African allele associated with the DYS199 T allele in any of the Native American or native Siberian populations. However, we did find DYS287 YAP+ individuals who harbored the DYS199 C allele in one Native American population, the Mixe, and in one Asian group, the Tibetans. A correlation of these Y chromosome alleles in Native Americans with those of the DYS1 locus, as detected by the p49a/p49f (p49a,f) probes on TaqI-digested genomic DNA, revealed a complete association of DYS1 alleles (p49a,f haplotypes) 13, 18, 66, 67 and 69 with the DYS199 T allele, while DYS1 alleles 8 and 63 were associated with both the DYS199 C and T allele.     

Offset Fresnel zone plate antennas

The theory of offset Fresnel zone plate antennas is presented. Explicit formulae for the design of the zone boundaries for the offset Fresnel zone plate are given. Theorectical equations and numerical results for the far-field analysis are presented. It is found that when the offset angle increases, the zone boundaries become more elliptic and the plate becomes more asymmetric in the E-plane. With the number of full wave zones and the plate width in the W-plane fixed, the plate width in the E-plane increases with the offset angle, which keeps the projected aperture area constant. Within a limited range of offset angles, the offset configuration can be employed without degrading the radiation performance much. For large offset angles, however, the asymmetry of the configuration may lead to increased sidelobes and decreased antenna directivity. An experiment with one particular phase reversal zone plate antenna with 30° offset angle shows good agreement between the measured antenna pattern and the theoretical prediction.