Effect of orexin-A on discharge rate of rat suprachiasmatic nucleus neurons in vitro

The suprachiasmatic nuclei (SCN) constitute the principal pacemaker of the circadian timing system in mammals. The generated rhythm is forwarded mostly through projections to various hypothalamic nuclei. On the other hand, the regulated processes feedback to the SCN. One of the possible feedback pathways is the orexinergic projection from the lateral hypothalamus. Orexins are recently identified neuropeptides with an overall facilitatory effect on waking behaviors. Orexinergic fibers are widely distributed throughout the brain and are also present in the SCN. In this study we examined the effect of orexin-A on the spontaneous activity of rat SCN cell in vitro. Neurons showed 2 different firing pattern (continuous-regular, intermittent-irregular). Orexin-A increased firing rate in both cell types at 10(-8) M concentration, but caused a clear suppression of neuronal activity at 10(-7) M. Continuously firing neurons were less responsive than those firing intermittently. These results show that orexin-A may play a role in the modulation of the circadian pacemaker function. The neuropeptide might exert both direct, postsynaptic effects on SCN neurons and indirect, presynaptic effects on excitatory and inhibitory terminals. The dose-dependent modification of the firing rate indicate that the weight of these factors changes with the concentration of orexin-A.     

Rapamycin inhibits primary and metastatic tumor growth by antiangiogenesis: involvement of vascular endothelial growth factor

Conventional immunosuppressive drugs have been used effectively to prevent immunologic rejection in organ transplantation. Individuals taking these drugs are at risk, however, for the development and recurrence of cancer. In the present study we show that the new immunosuppressive drug rapamycin (RAPA) may reduce the risk of cancer development while simultaneously providing effective immunosuppression. Experimentally, RAPA inhibited metastatic tumor growth and angiogenesis in in vivo mouse models. In addition, normal immunosuppressive doses of RAPA effectively controlled the growth of established tumors. In contrast, the most widely recognized immunosuppressive drug, cyclosporine, promoted tumor growth. From a mechanistic perspective, RAPA showed antiangiogenic activities linked to a decrease in production of vascular endothelial growth factor (VEGF) and to a markedly inhibited response of vascular endothelial cells to stimulation by VEGF. Thus, the use of RAPA, instead of cyclosporine, may reduce the chance of recurrent or de novo cancer in high-risk transplant patients.     

Development of Hydrotaea aenescens (Diptera: Muscidae) in manure of unweaned dairy calves and lactating cows

In laboratory studies performed in the United States and Hungary, the dump fly Hydrotaea aenescens (Wiedemann) was reared successfully in manure of 1- to 8-wk-old dairy calves, and in manure from adult lactating dairy cows. Survival in manure collected from 1-wk-old calves was poor (7.2%), better in manure collected from 2- and 3-wk-old calves (53.5%), and best in manure collected from 4- to 8-wk-old calves (71.4%). Survival in cow manure was slightly lower (47.4%) than that in calf manure. Reasons for different rates of development in the United States and in Hungary, and by calf age are discussed as are implications for biological control.     

A comparison of Lucitraps and sticky targets for sampling the blowfly Lucilia sericata

The Lucitrap (Miazma Pty Ltd, Queensland, Australia) combined with a synthetic odour bait, Lucilure (Miazma Pty Ltd, Queensland, Australia), is a commercially available trap for sampling and control of Lucilia cuprina (Wiedemann) in Australia. It was tested in Hungary against Lucilia sericata (Meigen) (Diptera: Calliphoridae), a cause of sheep strike throughout temperate Europe. The standard Lucitrap was tested against black or yellow sticky target traps. Both trap types were baited with either Lucilure or liver and 10% w/v sodium sulphide solution. With Lucilure as bait, L. sericata were caught on sticky traps but not in Lucitraps. With liver and sodium sulphide as bait, sticky traps caught 500-1500 times more L. sericata than Lucitraps. An adhesive sheet fitted to the top of a Lucitrap captured 30-300 times more L. sericata then were captured inside an unaltered Lucitrap. Direct observation of metallic green calliphorids (92.1% L. sericata) alighting on Lucitraps indicated that most flies stayed for a short while (modal class 2-4 s) and only a few stayed longer, to an observed maximum of 28 s. Flies explored a mean of 1.5 entry holes (range 0-7) during a visit but only 6% entered the trap. Size of L. sericata was not a physical barrier to Lucitrap entry, because many larger species were captured. However, L. sericata captured inside Lucitraps were significantly smaller than those captured on sticky traps, demonstrating that size was of behavioural importance. The data demonstrate that the Lucitrap is not effective as a trap for L. sericata in Hungary, due mainly to a failure of flies to enter the trap in large numbers. In Australia and South Africa, L. sericata is commonly caught in Lucitraps baited with Lucilure, although L. cuprina is more numerous. Our study highlights the potential for diversity of fly behaviour between different geographical populations of the same species. Such diversity can have a significant effect on the functioning of systems for fly sampling and control, when these systems depend for their success on certain behavioural responses of the target species.     

Multiparameter analysis of human epithelial tumor cell lines by laser scanning cytometry

Laser scanning cytometry (LSC) is a relatively new slide-based technology developed for commercial use by CompuCyte (Cambridge, MA) for performing multiple fluorescence measurements on individual cells. Because techniques developed for performing four or more measurements on individual lymphoid cells based on light scatter as a triggering parameter for cell identification are not suitable for the identification of fixed epithelial tumor cells, an alternative approach is required for the analysis of such cells by LSC. Methods for sample preparation, event triggering, and the performance of multiple LSC measurements on disaggregated fixed human cells were developed using normal lymphocytes and two human breast cancer cell lines, JC-1939 and MCF-7, as test populations. Optimal conditions for individual cell identification by LSC were found to depend on several factors, including deposited cell density (cells per unit area), the dynamic range of probe fluorescence intensities, and intracellular distribution of the fluorescent probe. Sparsely deposited cells exhibited the least cell overlap and the brightest immunofluorescent staining. Major advantages of using DNA probes over a cytoplasmic immunofluorescent protein marker such as tubulin for event triggering are that the former exhibit greater fluorescence intensity within a relatively sharply demarcated nuclear region. The DNA-binding dye LDS-751 was found to be suboptimal for quantitative DNA measurements but useful as a triggering measurement that permits the performance of simultaneous fluorescein isothiocyanate-, phycoerythrin-, and indodicarbocyanine-based measurements on each cell. A major potential advantage of LSC over flow cytometry is the high yields of analyzable cells by LSC, permitting the performance of multiple panels of multicolor measurements on each tumor. In conclusion, we have developed and optimized a technique for performing multiple fluorescence measurements on fixed epithelial cells by LSC based on event triggering using the DNA-binding dye LDS 751. Although not ideal for quantitative measurements of cell DNA content, the large Stokes shift of this dye permits the performance of three or more additional fluorescence measurements on each cell.     

Some factors affecting metal ion-monohydroxamate interactions in aqueous solution

The chelating properties exhibited by a series of monohydroxamic acids (propanohydroxamic acid (Pha), hexanohydroxamic acid (Hha), benzohydroxamic acid (Bha), N-methyl-acetohydroxamic acid (MAha), N-phenyl-acetohydroxamic acid (PhAha) and 2-hydroxypyridine-N-oxide (PYRha)) towards copper(II), nickel(II), zinc(II), calcium(II), magnesium(II) and aluminium(III) ions were studied by pH-metric, spectrophotometric and, in one case, by 27Al NMR methods. The results were compared with the corresponding data for metal ion-acetohydroxamate (Aha) and metal ion-desferrioxamine B (DFB) complexes. Changes of the substituents either on the carbon or on the nitrogen of the hydroxamate moiety caused a measurable effect on the chelate stability only in the case of aluminium(III) complexes. The aromatic derivative, PYRha, formed significantly more stable complexes than expected on the basis of the ligand basicity. The higher complex-forming ability of DFB compared to monohydroxamic acids diminishes in the case of the largest calcium(II) ion.     

Out of Africa and back again: nested cladistic analysis of human Y chromosome variation

We surveyed nine diallelic polymorphic sites on the Y chromosomes of 1,544 individuals from Africa, Asia, Europe, Oceania, and the New World. Phylogenetic analyses of these nine sites resulted in a tree for 10 distinct Y haplotypes with a coalescence time of approximately 150,000 years. The 10 haplotypes were unevenly distributed among human populations: 5 were restricted to a particular continent, 2 were shared between Africa and Europe, 1 was present only in the Old World, and 2 were found in all geographic regions surveyed. The ancestral haplotype was limited to African populations. Random permutation procedures revealed statistically significant patterns of geographical structuring of this paternal genetic variation. The results of a nested cladistic analysis indicated that these geographical associations arose through a combination of processes, including restricted, recurrent gene flow (isolation by distance) and range expansions. We inferred that one of the oldest events in the nested cladistic analysis was a range expansion out of Africa which resulted in the complete replacement of Y chromosomes throughout the Old World, a finding consistent with many versions of the Out of Africa Replacement Model. A second and more recent range expansion brought Asian Y chromosomes back to Africa without replacing the indigenous African male gene pool. Thus, the previously observed high levels of Y chromosomal genetic diversity in Africa may be due in part to bidirectional population movements. Finally, a comparison of our results with those from nested cladistic analyses of human mtDNA and beta-globin data revealed different patterns of inferences for males and females concerning the relative roles of population history (range expansions) and population structure (recurrent gene flow), thereby adding a new sex-specific component to models of human evolution.