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Multiple Cycles (multiple + cycle)
Selected AbstractsQuaternary paleoenvironments and potential for human exploitation of the Jordan plateau desert interiorGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2005Caroline P. Davies The physical, chemical, numerical, and radiometric analyses of a 31-m sediment core from the Qa'el-Jafr basin provide an important record of Quaternary paleoenvironments for the Jordan Plateau and evidence for several significant changes in climate regime. Cluster and PCA analyses of the geochemical data support the designation of major sedimentation regimes identified by stratigraphic and sediment analyses. Multiple cycles of alluvial deposition, lacustrine units, and erosional unconformities characterize the deepest sediments, followed by a period(s) of intense evaporation. Radiocarbon ages of charcoal in the uppermost 7 m place the aeolian/alluvial phase between 16,030 ± 140 yr B.P. and 24,470 ± 240 yr B.P. Deflation processes may explain the lack of a Holocene sequence. Despite lacking radiometric ages for the lower sediments, the thickness and degree of calcium-carbonate cementation suggest considerable age for the basal sediments, which suggests that a very long terrestrial record of Quaternary climate changes has been preserved in the Jafr basin. This new record of paleoenvironments provides important context to the archaeological record of the Jordan Plateau during the Quaternary. Several archaeological surveys demonstrate extensive human exploitation of lakes and springs of the major wadis along the western margin of the Rift Valley. However, little is known of human exploitation of the desert interiors. Qa'el-Jafr sediments demonstrate significant lacustrine and high moisture phases sufficient for human exploitation of the eastern desert during the Pleistocene. © 2005 Wiley Periodicals, Inc. [source] An ex vivo swine tracheal organ culture for the study of influenza infectionINFLUENZA AND OTHER RESPIRATORY VIRUSES, Issue 1 2010Sandro F. Nunes Background The threat posed by swine influenza viruses with potential to transmit from pig populations to other hosts, including humans, requires the development of new experimental systems to study different aspects of influenza infection. Ex vivo organ culture (EVOC) systems have been successfully used in the study of both human and animal respiratory pathogens. Objectives We aimed to develop an air interface EVOC using pig tracheas in the study of influenza infection demonstrating that tracheal explants can be effectively maintained in organ culture and support productive influenza infection. Methods Tracheal explants were maintained in the air interface EVOC system for 7 days. Histological characteristics were analysed with different staining protocols and co-ordinated ciliary movement on the epithelial surface was evaluated through a bead clearance assay. Explants were infected with a swine H1N1 influenza virus. Influenza infection of epithelial cells was confirmed by immunohistochemistry and viral replication was quantified by plaque assays and real-time RT-PCR. Results Histological analysis and bead clearance assay showed that the tissue architecture of the explants was maintained for up to 7 days, while ciliary movement exhibited a gradual decrease after 4 days. Challenge with swine H1N1 influenza virus showed that the EVOC tracheal system shows histological changes consistent with in vivo influenza infection and supported productive viral replication over multiple cycles of infection. Conclusion The air interface EVOC system using pig trachea described here constitutes a useful biological tool with a wide range of applications in the study of influenza infection. [source] Current modalities and new advances in the treatment of basal cell carcinomaINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 5 2006Roger I. Ceilley MD Basal cell carcinoma (BCC) is one of the most common cancers. Surgical extirpation is currently the standard of care for BCC, which is associated with several advantages and disadvantages. Procedures such as surgical excision used to treat superficial BCC (sBCC) and nodular BCC (nBCC) may have high 5-year recurrence rates if tumors are not completely excised. Curettage with electrodesiccation is a common method for treating primary BCC. However, multiple cycles are recommended and the procedure can have unsatisfactory cosmetic results (e.g. scarring and hypopigmentation). Mohs micrographic surgery has a low rate of disease recurrence but is a specialized procedure usually limited to specific indications (e.g. high-risk tumors). Cryosurgery and photodynamic therapy require multiple cycles and are associated with variable cosmetic outcomes and recurrence rates. As with any procedure, potential risks and patient quality-of-life issues need to be considered. In addition, substantial patient and healthcare provider inconvenience limit the practical utility of some modalities. Pharmacologic interventions provide another treatment option as adjunctive or monotherapy. Investigations of imiquimod, a novel immune response modifier, have indicated that this topical, noninvasive agent is safe and well tolerated and may be efficacious in the treatment of BCC. This review will highlight the role of standard treatment modalities and introduce new advances in the treatment of BCC. [source] Recyclable Polymer- and Silica-Supported Ruthenium(II)-Salen Bis-pyridine Catalysts for the Asymmetric Cyclopropanation of OlefinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Christopher Abstract Homogeneous ruthenium(II)-salen bis-pyridine complexes are known to be highly active and selective catalysts for the asymmetric cyclopropanation of terminal olefins. Here, new methods of heterogenization of these Ru-salen catalysts on polymer and porous silica supports are demonstrated for the facile recovery and recycle of these expensive catalysts. Activities, selectivities, and recyclabilities are investigated and compared to the analogous homogeneous and other supported catalysts for asymmetric cyclopropanation reactions. The catalysts are characterized with a variety of methods including solid state cross-polarization magic-angle spinning (CP MAS) 13C and 29Si,NMR, FT-IR, elemental analysis, and thermogravimetric analysis. Initial investigations produced catalysts possessing high selectivities but decreasing activities upon reuse. Addition of excess pyridine during the washing steps between cycles was observed to maintain high catalytic activities over multiple cycles with no impact on selectivity. Polymer-supported catalysts showed superior activity and selectivity compared to the porous silica-supported catalyst. Additionally, a longer, flexible linker between the Ru-salen catalyst and support was observed to increase enantioselectivity and diastereoselectivity, but had no effect on activity of the resin catalysts. Furthermore, the polymer-supported Ru-salen-Py2 catalysts were found to generate superior selectivities and yields compared to other leading heterogeneous asymmetric cyclopropanation catalysts. [source] Virological characterization of patients treated early is able to control HIV-1 replication after multiple cycles of structured therapy interruptionJOURNAL OF MEDICAL VIROLOGY, Issue 8 2007G. Rozera Abstract This study aimed to define clinical and virological parameters associated with spontaneous control of HIV replication in patients having initiated HAART during primary HIV infection, who underwent structured therapy interruption by two protocols with either fixed or HIV viremia-guided scheme. At the end of the protocol all patients were changed to viremia-guided scheme and observed for 12 months (follow-up). Patients maintaining HIV viremia below the indications for resumption of HAART during the follow-up, were defined controllers, those who had to resume HAART were defined non-controllers. The following parameters were examined: pre-interruption therapy duration, CD4+, HIV RNA, proviral DNA, evolution of viral quasispecies. No specific advantage was conferred by either interruption of structured therapy in the proportion of controllers and non-controllers. Pre-HAART and zenith CD4+, pre-therapy interruption, HAART duration, but not pre-HAART HIV RNA, were significantly higher in controllers as compared to non-controllers. HIV RNA levels after the first interruption cycle of therapy were significantly lower in controllers than in non-controllers. Proviral DNA levels were also lower in controllers at this time point. HIV RNA and proviral DNA levels associated with the last interruption of therapy cycle were not different from those associated with the first cycle, and, in spite of multiple waves of virus rebound, very few gag quasispecies variants emerged in each patient. The data suggest that pre-treatment clinical parameters and virological events associated with the first viral rebound are crucial factors in determining the ability to control viral replication after multiple cycles of interruption of treatment. J. Med. Virol. 79: 1047,1054, 2007. © 2007 Wiley-Liss, Inc. [source] Only Male Mice Show Sensitization of Handling-Induced Convulsions Across Repeated Ethanol Withdrawal CyclesALCOHOLISM, Issue 3 2007L.M. Veatch Background: Alcohol abuse, especially when experienced in multiple cycles of chronic abuse and withdrawal, leads to a sensitization of central nervous system hyperexcitability that may culminate in overt expression of seizures. In spite of the growing prevalence of alcohol abuse and dependence in females shown in recent epidemiologic studies, evidence of sexual dimorphism in the expression of alcohol withdrawal-induced seizures and the development of seizure sensitization following multiple cycles of ethanol (EtOH) exposure and withdrawal has not been examined in either animal models or in clinical reports. Methods: Subjects in these experiments were male and female C3H/Hecr mice. The female mice were intact or ovariectomized, with ovariectomized mice receiving 17- , -estradiol or placebo pellets. All mice were exposed to 4 cycles of exposure to 16-hour EtOH vapor, separated by 8-hour withdrawal periods. During each 8-hour withdrawal, hourly assessment of seizure propensity was assessed as handling-induced convulsions. Additional assessments were taken up to 72 hours after the final EtOH withdrawal cycle. Results: Male and female mice showed similar seizure propensity during an initial withdrawal from chronic EtOH. Across subsequent withdrawal cycles, however, male mice exhibited a robust increase in seizure severity beginning with the third withdrawal cycle. In marked contrast, female mice failed to demonstrate sensitization of seizure severity. The lack of seizure sensitization following up to 4 cycles of alcohol exposure and withdrawal could not be explained by hormonal status (presence or absence of estrogen) or by sex differences in blood alcohol levels. Conclusions: Male and female mice exposed to the same number of cycles of EtOH withdrawal demonstrate differences in expression of seizures. Males show the typical sensitization of seizures, or kindling response, which has been reported clinically as well as in animal models, but females do not. The reason for the lack of seizure sensitization in female mice remains to be elucidated, but may be related to sex differences in alcohol effects on excitatory/inhibitory neurotransmission, rather than to hormonal or blood alcohol level differences. [source] Rapid and efficient mapping of regional ventilation in the rat lung using hyperpolarized 3He with Flip angle variation for offset of RF and relaxation (FAVOR)MAGNETIC RESONANCE IN MEDICINE, Issue 6 2008Giles E. Santyr Abstract A novel imaging method is presented, Flip Angle Variation for Offset of RF and Relaxation (FAVOR), for rapid and efficient measurement of rat lung ventilation using hyperpolarized helium-3 (3He) gas. The FAVOR technique utilizes variable flip angles to remove the cumulative effect of RF pulses and T1 relaxation on the hyperpolarized gas signal and thereby eliminates the need for intervening air wash-out breaths and multiple cycles of 3He wash-in breaths before each image. The former allows an improvement in speed (by a factor of ,30) while the latter reduces the cost of each measurement (by a factor of ,5). The FAVOR and conventional ventilation methods were performed on six healthy male Brown Norway rats (190,270 g). Lobar measurements of ventilation, r, obtained with the FAVOR method were not significantly different from those obtained with the conventional method for the right middle and caudal and left lobes (P > 0.05 by a Wilcoxon matched pairs test). A methacholine challenge test was also administered to an animal and reduction and recovery of r was detected by the FAVOR method. The reduced 3He consumption and the improvement in speed provided by FAVOR suggest that it may allow measurement of ventilation in human subjects not previously possible. Magn Reson Med 59:1304,1310, 2008. © 2008 Wiley-Liss, Inc. [source] Differential response of Amaranthus tuberculatus (Moq ex DC) JD Sauer to glyphosatePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 10 2005Ian A Zelaya Abstract Midwest USA farmers have reported inconsistent control of Amaranthus tuberculatus (= rudis) (Moq ex DC) JD Sauer by glyphosate in glyphosate-resistant crops. The potential of selection for decreased A tuberculatus sensitivity to glyphosate was therefore investigated in a reportedly resistant Everly, IA population (P0,EV). Evaluation of six A tuberculatus populations from the Midwest USA estimated a seedling baseline sensitivity of 2.15 mM glyphosate. Based on these results, three generations of divergent recurrent selection were implemented on P0,EV to isolate resistant and susceptible populations. A seedling assay was developed to screen large amounts of seeds and thus expedite the selection process. Whole-plant and seedling rate responses of P0,EV and a known pristine A tuberculatus population from Paint Creek, OH (P0,WT) identified no significant difference in response to glyphosate; however, greater phenotypic variance was ostensibly evident in P0,EV. The first recurrent generation selected for resistance at 3.2 mM glyphosate (RS1,R) had a 5.9- and 1.7-fold resistance increase at the seedling and whole-plant levels, respectively, compared with the susceptible generation selected at 32 µM glyphosate. After three cycles of recurrent selection, 14.6-fold difference in resistance at the seedling level and 3.1-fold difference at the whole-plant level were observed when comparing the populations selected for resistance (RS3,R) and susceptibility (RS3,S). Overall, recurrent selection increased the frequency of resistant individuals and decreased the variability to glyphosate at the population level. Nevertheless, variability for glyphosate resistance was still evident in RS3,R. Results herein suggested that A tuberculatus is inherently variable to glyphosate and that selection decreased the sensitivity to glyphosate. We purport that evolved glyphosate resistance in A tuberculatus may require multiple cycles of selection under field conditions. Historic estimated use of glyphosate alludes to the evolution of tolerant weed populations. Copyright © 2005 Society of Chemical Industry [source] Susceptibility of invasive taxa of European blackberry to rust disease caused by the uredinial stage of Phragmidium violaceum under field conditions in AustraliaPLANT PATHOLOGY, Issue 3 2005K. J. Evans European blackberry (Rubus fruticosus agg.) is an aggregate of closely related taxa, with at least 15 taxa naturalized in Australia. Biological control of this Weed of National Significance, using the nonindigenous rust fungus Phragmidium violaceum, is effective when the weather is conducive to multiple cycles of infection, but some blackberry taxa escape severe disease. Thirty-one taxa of naturalized R. fruticosus agg. from southeastern Australia were isolated, their DNA phenotype determined and clones of each taxon inoculated with P. violaceum isolate SA1. Disease development was monitored for at least four generations of uredinia on large potted plants under field conditions. Although variation in mean disease severity appeared continuous over the range of Rubus clones tested, counts of uredinia and telia enabled identification of eight resistant taxa. Fine scale variation in susceptibility to rust disease was observed when different clones of R. leucostachys with the same DNA phenotype were found to express either resistance or susceptibility to P. violaceum (SA1). There were significant differences among 23 Rubus taxa rated as susceptible to rust disease in the mean number of leaves emerging per latent period of uredinia (LELPU). Mean LELPU appeared to account for some of the variation in two measures of mean disease severity observed among susceptible Rubus clones, although the correlation was insignificant (0·10 < P > 0·05). [source] Bayesian Adaptive Regression Splines for Hierarchical DataBIOMETRICS, Issue 3 2007Jamie L. Bigelow Summary This article considers methodology for hierarchical functional data analysis, motivated by studies of reproductive hormone profiles in the menstrual cycle. Current methods standardize the cycle lengths and ignore the timing of ovulation within the cycle, both of which are biologically informative. Methods are needed that avoid standardization, while flexibly incorporating information on covariates and the timing of reference events, such as ovulation and onset of menses. In addition, it is necessary to account for within-woman dependency when data are collected for multiple cycles. We propose an approach based on a hierarchical generalization of Bayesian multivariate adaptive regression splines. Our formulation allows for an unknown set of basis functions characterizing the population-averaged and woman-specific trajectories in relation to covariates. A reversible jump Markov chain Monte Carlo algorithm is developed for posterior computation. Applying the methods to data from the North Carolina Early Pregnancy Study, we investigate differences in urinary progesterone profiles between conception and nonconception cycles. [source] Performance Characteristics of Nanoporous Carbon Membranes for Protein UltrafiltrationBIOTECHNOLOGY PROGRESS, Issue 5 2007Tapan N. Shah Nanoporous carbon membranes could be very attractive for applications of ultrafiltration in the biotechnology industry because of their greater mechanical strength and longer membrane life. The objective of this study was to obtain quantitative data on the performance characteristics of nanoporous carbon membranes formed within a stainless steel support that was first modified by deposition of silica particles within the macroporous support. The nanoporous carbon membrane effectively removed small solutes from a protein solution using diafiltration, with performance comparable to that of commercial polymeric membranes. Protein fouling was evident, although the nanoporous carbon membranes were easily regenerated; cleaning with 0.5 N NaOH at 50 °C completely restored the water permeability for multiple cycles. The nanoporous carbon membranes were also compatible with steam sterilization. Significant increases in process flux could be obtained using periodic back-pulsing, with no evidence of any structural alterations in the membrane. These results clearly demonstrate the potential benefits and opportunities for using nanoporous carbon membranes for protein ultrafiltration. [source] Improved Fermentation Processes for NS0 Cell Lines Expressing Human Antibodies and Glutamine SynthetaseBIOTECHNOLOGY PROGRESS, Issue 1 2003Jonathan Dempsey To meet the increasing requirement for therapeutic antibodies to conduct clinical trials, an enhanced culture medium and fed-batch process was developed for GS-NS0 cell lines. This process was shown to produce high concentrations of monoclonal antibodies for several cell lines expressing different antibodies. Cells were adapted to growth in a glutamine- and serum-free medium containing bovine serum albumin (BSA), cholesterol, and transferrin. A number of amino acids were found to be depleted during cell culture. The concentrations of these amino acids were increased, and further cell culture analyses were performed. This process of cell growth and analysis was repeated over multiple cycles until no depletion was detected. This resulted in an amino acid supplement that was shown to be generic and enhanced antibody productivity up to 5-fold for the three cell lines tested. Transferrin was replaced using tropolone, a lipophilic iron chelator and ferric ammonium citrate. Cell growth was equivalent to that in transferrin-containing medium over the wide ranges tested. A concentrated feed solution, based on the amino acid supplement and the components of the serum-and protein-free supplements, was formulated. Addition of this feed in response to metabolic requirements resulted in a harvest titer a further 2-fold higher than the enhanced culture medium. Harvest antibody titers of up to 600 mg/L were achieved for three cell lines expressing different antibodies, representing an increase of 10-fold over the starting concentrations. [source] 2433: A revolutionary hypothesis to explain Marx's line and progressive disease at the lid marginACTA OPHTHALMOLOGICA, Issue 2010AJ BRON Purpose The conjunctiva of the lid margin is protected from direct exposure to the atmosphere, by the tear meniscus. We examine the pathophysiological consequences of evaporation from this compartment. Methods A consideration of empirical data. Results The concave meniscus thins progressively to the point where it is pinned at the mucocutaneous junction (MCJ). We predict that, as a result, over the interblink period, evaporation generates a solute gradient which peaks behind the MCJ and is amplified over multiple cycles of the blink. We hypothesise that this creates a hyperosmolar state here which: i. stresses epithelial cells behind the MCJ, ii. stimulates a high cell turnover and iii. leads to immaturity of the surface cells and their glycocalyx. This is considered to explain an increased permeability to dyes at this site (rose bengal, lissamine green and fluorescein) and the stainability with dyes which is termed Marx's line. This gradient mechanism could also concentrate proteins, such as inflammatory mediators, at this location. Conclusion Since Marx's line lies directly behind the terminal Meibomian ducts and acini, chronic stress in this region is further invoked to explain forward migration of Marx's line and the MCJ which occurs with age and the induction of primary Meibomian gland dysfunction. Arguments are put forward to explain how this mechanism might be accentuated in dry eye and how the globe might be protected from this gradient effect in the region of the ,black line', where the tear film is segregated from the meniscus after the blink. Factors pro and con the hypothesis are discussed. [source] A new strategy based on recombinant viruses as a tool for assessing drug susceptibility of human immunodeficiency virus type 1JOURNAL OF MEDICAL VIROLOGY, Issue 2 2007J. Garcia-Perez Abstract The emergence of drug-resistant variants during antiretroviral therapy is a serious obstacle to sustained suppression of the human immunodeficiency virus type 1 (HIV-1). For that reason, resistance assays are essential to guide clinicians in the selection of optimal treatment regimens. Genotypic assays are less expensive and results are available faster than phenotypic assays. However, in heavily experienced patients with multiple treatment failures interpretation of complex mutation patterns remains difficult, and in these cases phenotypic assays are recommended. This report describes a novel recombinant virus assay where protease (PR) and reverse transcriptase (RT) sequences derived from the plasma isolated from patients are introduced into the back-bone of an HIV molecular clone that expresses Renilla luciferase protein in the place of nef gene. All drug resistance profiles analyzed correlate with previously reported data and showed high reproducibility. This assay, in addition to a fast (completed in 10 days), precise, reproducible and automated method, presents several advantages as compared to other phenotypic assays. The system described below allows the generation of recombinant viruses with multiples cycles of replication carrying a reporter gene in their genomes. These features increase the sensitivity of the test, an important aspect to be considered in the evaluation of less fit viral isolates. In conclusion, the assay permits the quantitation of the level of resistance of clinical HIV-1 isolates to PR and RT inhibitors. J. Med. Virol. 79:127,137, 2007. © 2006 Wiley-Liss, Inc. [source] | ||||||||||||||||