bluuebunny/crossref_metadata_2025_split huggingface dataset:
A parameter for the distribution of fluorophores in cells derived from measurements of inner filter effect and reabsorption phenomenon
Authors: Tanke H. J. , van Oostveldt P. , van Duijn P. 
Published: June 2010

AbstractThe linear relationship between the emitted fluorescence and the amount of fluorophore at relatively high local absorbance values is significantly disturbed by two major phenomena, inner filter effect and reabsorption of fluorescence emission light. For a theoretical model in which excitation and emission rays were considered parallel and the fluorophore distribution was assumed to be homogeneous, Rigler (Acta Physiol Scand (Suppl.) 267:1, 1966) showed that these errors become significant at local absorbance >0.1 and may become more important for heterogeneously stained cells measured with conical illumination.In this study we demonstrate theoretically and experimentally that the inner filter effect and reabsorption phenomenon depend not only on the average local absorption but also on the distribution of the fluorophore in the measuring field. The ratio of the fluorescence intensities in the longer and the shorter emission wavelength range is introduced as a new parameter called the “heterogeneity index.” This index is not affected by the total amount of fluorophore, but depends on the fluorophore distribution within the measuring field.The theory has been tested on Sephadex beads and glycoprotein films stained with periodic acid acriflavine‐SO2 or acrolein acriflavine‐SO2. The results of the measurements on the model systems were found to be qualitatively in agreement with the theoretical predictions.Heterogeneity index measurements on Feulgen acriflavine‐SO2 stained cells using both microscope fluorometry and flow cytometry showed significant differences for cell nuclei with the same total amount of fluorophore but with different fluorophore distributions. The avoidance of inner filter effect and reabsorption phenomenon or their use to study changes in DNA compactness such as occur during cell differentiation and degeneration are discussed.
Biophysical identification and sorting of high metastatic variants from B16 melanoma tumor
Authors: Lessin Stuart R. , Abraham Samuel R. , Nicolini Claudio 
Published: June 2010

AbstractChromatin structure, in terms of higher order nuclear‐DNA condensation (scanning cytometry) and in terms of acridine orange primary binding sites (flow cytometry), is analyzed and shown to be significantly different between high (B16‐F10) and low (B16‐F1) metastatic variants of B16 melanoma. Furthermore, double staining of B16‐F10 and B16‐F1 with ethidium bromide (chromatin) and fluorescamine (membranes) provides the identification of a homogeneous subpopulation of cells with enhanced metastatic potential based on differential fluorescamine uptake. Fluorescamine uptake and poststaining viability is shown to be dependent upon the dye/cell ratio at which staining occurs. Utilizing a sterile cell sorting technique, a subpopulation of B16‐F10 with increased fluorescamine uptake representing 30% of the total “intact cell” population was isolated by means of a fluorescence activated cell sorter and replated in vitro. This subpopulation when assayed in vivo produced significantly more pulmonary metastases than its parent cell line. Scanning cytometry of the Feulgen stained sorted subpopulation reveals that the cells possess a unique nuclear morphometry characterized by a 2C‐3C DNA content and a large nuclear area (disperse chromatin). Finally, when we assay simultaneously for nuclear‐DNA organization and cell membrane organization a progressive uncoupling between nuclear and cell morphometry is apparent in B16‐F10 (versus B16‐F1).
Stage‐related variations in DNA fluorescence distribution during rat spermatogenic cycle measured by flow cytometry
Authors: Clausen O. P. F. , Parvinen M. , Kirkhus Bente 
Published: June 2010

AbstractLiving segments of rat seminferous tubules representing the fourteen stages of the spermatogenic cycle have been isolated for DNA flow cytometry using the transillumination‐assisted microdissection procedure. The resulting DNA profiles showed stage‐related variations in the proportions of cells within the haploid (1C), diploid (2C) and tetraploid (4C) classes. Three distinct populations of haploid cells could be distinguished according to differences in fluorescence intensity of their nuclear DNA. The major haploid peak (1C) was found to reflect the steps 1–11 spermatids, the first hypofluorescent peak (fluorescence intensity from 0.45–0.75C) the steps 12–15 spermatids and the second hypofluorescent peak (fluorescence intensity of ca. 0.25C) the maturing steps 16–19 spermatids. The changes in fluorescence intensity could thus be correlated with nuclear protein transitions that are known to occur during spermiogenesis in rats. The results indicate that the processes responsible for the changes in nuclear fluorescence intensities are rapidly occurring, although not synchronously in all spermatids at the same developmental stages.
Reactions of 1,2,4‐Trithiolane and Its 4‐S‐Oxide with Diphosphane Pt0 Complexes
Authors: Petzold Holm , Weisheit Thomas , Bräutigam Silvio , Görls Helmar , Mloston Grzegorz , Weigand Wolfgang 
Published: June 2010

AbstractReactions of 1,2,4‐trithiolanes with Pt0 complexes often proceed via an oxidative addition of the Pt0 complex fragment into the S–S bond and subsequent extrusion of a thioketone molecule by ring contraction. The six‐membered intermediate 5a, formed in the course of the reaction of the parent 1,2,4‐trithiolane (1a) and Pt0 complex 4, was detected bymeans of low‐temperature NMR spectroscopy. Stable derivatives of this type (compounds 9, 11 and 12) were isolated either by using (dppe)Pt0 complex 8 or 1,2,4‐trithiolane 4‐S‐oxide (10). The molecular structures of platinum complexes 9, 11 and 12, as well as their unexpected stability, are discussed.
Structure and Dynamics of Lanthanide(III) Complexes with an N‐Alkylated do3a Ligand (H3do3a = 1,4,7,10‐Tetraazacyclododecane‐1,4,7‐triacetic Acid): A Combined Experimental and DFT Study
Authors: Regueiro‐Figueroa Martín , Esteban‐Gómez David , de Blas Andrés , Rodríguez‐Blas Teresa , Platas‐Iglesias Carlos 
Published: June 2010

AbstractLanthanide(III) complexes with 10‐benzyl‐1,4,7‐tris(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane (H3L) have been investigated as model compounds of N‐alkylated LnIII–do3a complexes (H3do3a = 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid) with potential application in molecular imaging. The X‐ray structures of the [{Ln(L)(H2O)}4]·18H2O complexes (Ln = Eu or Tb) show that the metal ion is directly bound to the seven donor atoms of the ligand, with the nine‐coordination sphere completed by an oxygen atom of an inner‐sphere water molecule and an oxygen atom of a carboxylate group from a neighboring [Ln(L)] unit. This results in the formation of tetrameric units through the sharing of carboxylic groups between adjacent [Ln(L)(H2O)] complexes. Luminescence lifetime measurements recorded in H2O and D2O provide a number of coordinated water molecules (q) of 1.2, which indicates that the major species that exists in solution contains one inner‐sphere water molecule. The conformational properties of the [Ln(L)(H2O)] complexes (Ln = Gd or Lu) have been investigated by using density functional theory (DFT) calculations (B3LYP model). Our results indicate that the Δ(λλλλ) conformation is more stable than the Δ(δδδδ) one for both complexes. The interconversion between these two isomers may proceed either through the inversion of the five‐membered rings formed upon coordination of the 1,4,7,10‐tetraazacyclododecane (cyclen) unit, or through the stepwise rotation of the three acetate pendant arms. According to our calculations, the activation free energy for the arm‐rotation process (5.6 kcal mol–1) is much lower than that of the ring‐inversion path (14.6 kcal mol–1), which in turn is very similar to those determined experimentally for LnIII(dota) complexes. Thus, a low energy barrier for the arm‐rotation process appears to be responsible for the relatively fast isomer interconversion observed for LnIII(N‐alkylated do3a) complexes.
Facile Synthesis of Trisubstituted Allenynes by Phosphane‐Mediated Deoxygenation of 2,4‐Pentadiyn‐1‐ol
Authors: Jiang Huanfeng , Wang Wei , Yin Biaolin , Liu Weibing 
Published: June 2010

AbstractA facile method for the synthesis of trisubstituted allenynes has been developed. The process involves phosphane‐mediated deoxygenation of 2,4‐pentadiyn‐1‐ol derivatives. A variety of propargyl alcohols can be transformed into allenynes in moderate to good yields under mild reaction conditions.
(9H‐Fluoren‐9‐yl)methanesulfonyl (Fms): An Amino Protecting Group Complementary to Fmoc
Authors: Ishibashi Yoshitaka , Miyata Kengo , Kitamura Masato 
Published: June 2010

AbstractA sulfonamide‐based protecting group (PG), (9H‐fluoren‐9‐yl)methanesulfonyl (Fms), which can be used in a similar way to the well‐established Fmoc PG, was developed. The advantages of this new PG were demonstrated in the successful formation of a phosphonamide between an N‐Fms‐protected α‐phosphonoalanine monoester and secondary alkylamines, including (R)‐2‐phenylethylamine, (S)‐phenylalanine tert‐butyl ester (H‐Phe‐OtBu), H‐Pro‐Gly‐OtBu, and H‐Phe‐Phe‐OtBu, without formation of oxazaphospholine, which is a serious problem associated with the Fmoc PG. The success should pave the way to the solid‐phase synthesis of unnatural peptides substituted with α‐amino phosphonic acid (AP) at essentially any arbitrary position without significant modification of the Fmoc‐based chemistry that has been accumulated since Carpino's report in 1970. The N‐Fms‐AP monomer would attract much attention in the field of peptide mimetics.
Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignancies
Authors: Valdez Benigno C. , Andersson Borje S. 
Published: June 2010

AbstractDespite successful molecularly targeted, highly specific, therapies for hematologic malignancies, the DNA interstrand crosslinking agents, which are among the oldest and least specific cytotoxic drugs, still have an important role. This is particularly true in stem cell transplantation, where virtually every patient receives conditioning therapy with a DNA‐alkylating agent‐based program. However, due to concern about serious additive toxicities with combinations of different alkylating drugs, the last several years have seen nucleoside analogs, whose cytotoxic action follows vastly different molecular pathways, introduced in combination with alkylating agents. The mechanistic differences paired with different metabolic pathways for the respective drugs have clinically translated into increased safety without appreciable loss of antileukemic activity. In this report, we review pre‐clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA‐alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information‐backed hypothesis can be incorporated in the design of the next generation conditioning therapy programs in stem cell transplantation to optimize antileukemic efficacy while still safeguarding patient safety. Environ. Mol. Mutagen., 2010. © 2010 Wiley‐Liss, Inc.
Soil‐erosion models: where do we really stand?
Authors: Smith Roger E. , Quinton John , Goodrich David C , Nearing Mark 
Published: June 2010

AbstractWainwright et al. (2008a, b, c) propose a new model for simulating catchment‐scale erosion resulting from rainfall‐runoff events. In justification for such a new model, several existing process‐based models are criticized with regard to their theoretical underpinnings and presumptions. Since the authors do not correctly characterize the models mentioned, it is felt useful to correct the record in that regard, and to put the proposed model of Wainwright et al. in better perspective. The current models named in the criticism by Wainwright et al. include KINEROS (Woolhiser et al., 1990), KINEROS2 (Smith et al., 1995), EUROSEM (Morgan et al., 1998; Smith et al., 1995), and WEPP (Ascough et al., 1997). We refer to these below as the ‘critiqued models.’ The writers' familiarity with those models and their assumptions provide justification for the clarifications presented below. We note here that some of the models critiqued have had developments added, and published, since their initial release.Wainwright et al.'s complaints and misunderstandings regarding existing models appear in our reading to be summarised by the following statements:

Existing models assume all sediment travels in suspension, whereas it likely does not.
The description of sediment movement relies on an assumption based on steady‐state flow.
The models assume that sediment velocity is the same as water velocity.
The Yalin (1972) transport equation is criticized as inapplicable or misapplied [with the clear implication that existing models rely on it].
The models should not use settling velocity or are using it incorrectly (p. 817).
Below we address each of these points in detail. In each case the criticisms are ill‐founded or result from a misunderstanding of the conceptual robustness of current catchment erosion dynamic models. Being familiar with the ‘critiqued’ models, we point out what we feel to be the true weaknesses of erosion models, for which the MAHLERAN model, developed by Wainwright et al., offers no cure. Their model suffers from many of the same weaknesses as those critiqued, plus some unique ones of its own. Copyright © 2010 John Wiley & Sons, Ltd.
Surface and sub‐surface Schmidt hammer rebound value variation for a granite outcrop
Authors: Černá Barbora , Engel Zbyněk 
Published: June 2010

AbstractThis study presents rock strength variations at granite outcrops and in subsurface vertical profiles in the Jizerské hory Mountains, Czech Republic. Schmidt hammer rebound values in subsurface profiles change gradually from the bedrock surface downward. An exponential relation has been observed between the R‐values and depth in rock outcrops to a depth of around 4·5 m. The exponential nature of the curve indicates that rock hardness increases more rapidly with depth in the uppermost 1?m section of the rock profile. A detailed study of rebound values obtained from both intact and polished rock exposures reveal effects of surface grinding on results of the Schmidt hammer method. The range of data collected increases after grinding, allowing more precise discrimination of rock surfaces in respect of age and weathering. The Schmidt hammer method may be used effectively as a relative‐age dating tool for rock surfaces that originated during the Late Pleistocene. It is concluded that this time limitation can be significantly mitigated by surface grinding before measurement. Copyright © 2010 John Wiley & Sons, Ltd.
Focal cerebral ischemia induces a multilineage cytogenic response from adult subventricular zone that is predominantly gliogenic
Authors: Li Lu , Harms Kate M. , Ventura P. Britten , Lagace Diane C. , Eisch Amelia J. , Cunningham Lee Anna 
Published: June 2010

AbstractThe purpose of this study was to ascertain the relative contribution of neural stem/progenitor cells (NSPCs) of the subventricular zone (SVZ) to lineages that repopulate the injured striatum following focal ischemia. We utilized a tamoxifen‐inducible Cre/loxP system under control of the nestin promoter, which provides permanent YFP labeling of multipotent nestin+ SVZ‐NSPCs prior to ischemic injury and continued YFP expression in all subsequent progeny following stroke. YFP reporter expression was induced in adult male nestin‐CreERT2:R26R‐YFP mice by tamoxifen administration (180 mg kg−1, daily for 5 days). Fourteen days later, mice were subjected to 60‐min transient middle cerebral artery occlusion (MCAO) and sacrificed at 2 days, 2 weeks, or 6 weeks post‐MCAO for phenotypic fate mapping of YFP+ cells using lineage‐specific markers. Migration of YFP+ cells from SVZ into the injured striatal parenchyma was apparent at 2 and 6 weeks, but not 2 days, post‐MCAO. At 2 weeks post‐MCAO, the average percent distribution of YFP+ cells within the injured striatal parenchyma was as follows: 10% Dcx+ neuroblasts, 15–20% oligodendrocyte progenitors, 59% GFAP+ astrocytes, and only rare NeuN+ postmitotic neurons. A similar phenotypic distribution was observed at 6 weeks, except for an increased average percentage of YFP+ cells that expressed Dcx+ (20%) or NeuN (5%). YFP+ cells did not express endothelial markers, but displayed unique anatomical relationships with striatal vasculature. These results indicate that nestin+ NSPCs within the SVZ mount a multilineage response to stroke that includes a gliogenic component more predominant than previously appreciated. © 2010 Wiley‐Liss, Inc.
RIG‐I mediates nonsegmented negative‐sense RNA virus‐induced inflammatory immune responses of primary human astrocytes
Authors: Furr Samantha R. , Moerdyk‐Schauwecker Megan , Grdzelishvili Valery Z. , Marriott Ian 
Published: June 2010

AbstractWhile astrocytes produce key inflammatory mediators following exposure to neurotropic nonsegmented negative‐sense RNA viruses such as rabies virus and measles virus, the mechanisms by which resident central nervous system (CNS) cells perceive such viral challenges have not been defined. Recently, several cytosolic DExD/H box RNA helicases including retinoic acid‐inducible gene I (RIG‐I) have been described that function as intracellular sensors of replicative RNA viruses. Here, we demonstrate that primary human astrocytes constitutively express RIG‐I and show that such expression is elevated following exposure to a model neurotropic RNA virus, vesicular stomatitis virus (VSV). Evidence for the functional nature of RIG‐I expression in these cells comes from the observation that this molecule associates with its downstream effector molecule, interferon promoter stimulator‐1, following VSV infection and from the finding that a specific ligand for RIG‐I elicits astrocyte immune responses. Importantly, RIG‐I knockdown significantly reduces inflammatory cytokine production by VSV‐infected astrocytes and inhibits the production of soluble neurotoxic mediators by these cells. These findings directly implicate RIG‐I in the initiation of inflammatory immune responses by human glial cells and provide a potential mechanism underlying the neuronal cell death associated with acute viral CNS infections. © 2010 Wiley‐Liss, Inc.
Morphine induces the release of CCL5 from astrocytes: Potential neuroprotective mechanism against the HIV protein gp120
Authors: Avdoshina Valeriya , Biggio Francesca , Palchik Guillermo , Campbell Lee A. , Mocchetti Italo 
Published: June 2010

AbstractA number of human immunodeficiency virus type‐1 (HIV) positive subjects are also opiate abusers. These individuals are at high risk to develop neurological complications. However, little is still known about the molecular mechanism(s) linking opiates and HIV neurotoxicity. To learn more, we exposed rat neuronal/glial cultures prepared from different brain areas to opiate agonists and HIV envelope glycoproteins gp120IIIB or BaL. These strains bind to CXCR4 and CCR5 chemokine receptors, respectively, and promote neuronal death. Morphine did not synergize the toxic effect of gp120IIIB but inhibited the cytotoxic property of gp120BaL. This effect was blocked by naloxone and reproduced by the μ opioid receptor agonist DAMGO. To examine the potential mechanism(s) of neuroprotection, we determined the effect of morphine on the release of chemokines CCL5 and CXCL12 in neurons, astrocytes, and microglia cultures. CCL5 has been shown to prevent gp120BaL neurotoxicity while CXCL12 decreases neuronal survival. Morphine elicited a time‐dependent release of CCL5 but failed to affect the release of CXCL12. This effect was observed only in primary cultures of astrocytes. To examine the role of endogenous CCL5 in the neuroprotective activity of morphine, mixed cerebellar neurons/glial cells were immunoneutralized against CCL5 prior to morphine and gp120 treatment. In these cells the neuroprotective effect of opiate agonists was blocked. Our data suggest that morphine may exhibit a neuroprotective activity against M‐tropic gp120 through the release of CCL5 from astrocytes. © 2010 Wiley‐Liss, Inc.
In vivo observation of the locomotion of microglial cells in the retina
Authors: Paques Michel , Simonutti Manuel , Augustin Sébastien , Goupille Olivier , El Mathari Brahim , Sahel José‐Alain 
Published: June 2010

AbstractMicroglial cells (MCs) are active sensors and reactive phagocytes of neural tissues. They are known to migrate and accumulate in areas of neuronal damage. Thus, microglial locomotion is an essential feature of the inflammatory reaction in neural tissue. Yet, to our knowledge there has been no report of direct in vivo observation of the migration of MCs. Here, we show that intravitreally injected cyanine dyes (DiO, DiI, and indocyanine green) are sequestrated in MCs during several months, and subsequently in vivo images of these fluorescent MCs can be obtained by confocal scanning laser ophthalmoscopy. This enabled noninvasive, time‐lapse observation of the migrating behavior of MCs, both in the basal state and following laser damage. In the basal state, a slow, intermittent, random‐like locomotion was observed. Following focal laser damage, MCs promptly (i.e., within 1 h) initiated centripetal, convergent migration. MCs up to 400 μm away migrated into the scar at velocities up to 7 μm/min. This early phase of centripetal migration was followed by a more prolonged phase of nontargeted locomotion around and within injured sites during at least 24 h. Cyanine‐positive cells persisted within the scar during several weeks. To our knowledge, this is the first in vivo observation of the locomotion of individual MCs. Our results show that the locomotion of MCs is not limited to translocation to acutely damaged area, but may also be observed in the basal state and after completion of the recruitment of MCs into scars. © 2010 Wiley‐Liss, Inc.