bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mycobacterial infection inhibits established allergic inflammatory responses via alteration of cytokine production and vascular cell adhesion molecule‐1 expression
Authors: Yang Xi , Fan Yijun , Wang Shuhe , Han Xiaobing , Yang Jie , Bilenki Laura , Chen Lijun 
Published: March 2003

SummaryOur previous studies, as well as those of others, have demonstrated that local or systemic Mycobacterium bovis bacille Calmette–Gue´rin (BCG) infection can inhibit de novo allergen‐induced asthma‐like reactions, but the effect of this infection on established allergic responses is unknown. The aim of this study was therefore to examine the effect of mycobacterial infection on established allergy in a murine model of asthma‐like reaction. Mice were sensitized with ovalbumin (OVA) in alum followed by infection with BCG and subsequent intranasal challenge with the same allergen. In some experiments, mice were sensitized with OVA followed by intranasal challenge with OVA and then given BCG infection with subsequent rechallenge with OVA. Mice without BCG infection but treated with OVA in the same manner, were used as a control. The mice were examined for immunoglobulin E (IgE) response and eosinophilic inflammation, mucus production, cytokine/chemokine patterns and adhesion molecule expression in the lung. The results showed that postallergen BCG infection suppressed the established airway eosinophilia and mucus overproduction, but not IgE responses. The inhibition of asthma‐like reactions by BCG infection was correlated with a shift of allergen‐driven cytokine production pattern and, more interestingly, with a dramatic decrease of vascular cell adhesion molecule‐1 (VCAM‐1) expression in the lung. These findings suggest that intracellular bacterial infection can inhibit established allergic responses via alteration of local cytokine production and the expression of adhesion molecules.
The ramification and connections of retinal fibres in layer 7 of the domestic chick optic tectum: a Golgi impregnation, anterograde tracer and GABA‐immunogold study
Authors: Sebestény T. , Davies D. C. , Zayats N. , Németh A. , Tömböl T. 
Published: March 2003

AbstractLayer 7 is one of the retinorecipient layers of the avian optic tectum. However, little information is available about the neuronal organization of this layer and its implications for visual function. Golgi impregnation was used to investigate the retinal input to and the neuronal architecture of layer 7 of the chick optic tectum, which forms a narrow band between the two cell‐dense layers 6 and 8. Anterograde tracers were also used to investigate the afferent and efferent connections of layer 7, in both the light and the electron microscope, together with GABA immunogold labelling. Three types of radial neuron were defined according to the origin and course of their axons. The perikarya of these neurons were situated in tectal layers 10–11. The principal dendrites of these radial neurons ascended to the tectal surface and gave rise to dendritic side‐branches in layer 7. These dendritic side‐branches received asymmetric synapses from the terminations of retinal fibre arborisations. Type 2 radial neurons, whose axons arose from the deep pole of the perikaryon or occasionally from a basal dendrite, were shown to project to the nucleus isthmi pars magnocellularis, which has previously been demonstrated to be GABAergic and to project to glomerulus‐like complexes in tectal layers 4–5. In these layers, the dendritic branches of layer 13 neurons that project to the nucleus rotundus have previously been shown to receive retinal fibre input. Therefore, the retinal input to layer 7 may be able to modulate the transmission of information to the visual thalamus, by way of a feedback loop to layers 4–5 of the tectum involving the nucleus isthmi pars magnocellularis.
Study of the three‐dimensional geometry of the central conducting airways in man using computed tomographic (CT) images
Authors: Sauret V. , Halson P. M. , Brown I. W. , Fleming J. S. , Bailey A. G. 
Published: March 2003

AbstractClinical research on the deposition of inhaled substances (e.g. inhaled medications, airborne contaminants, fumes) in the lungs necessitates anatomical models of the airways. Current conducting airway models lack three‐dimensional (3D) reality as little information is available in the literature on the distribution of the airways in space. This is a limitation to the assessment or predictions of the particle deposition in relation to the subject’s anatomy. Detailed information on the full topology and morphology of the airways is thus required to model the airway tree realistically. This paper presents the length, diameter, gravity, coronal and sagittal angles that together describe completely the airways in 3D space. The angle at which the airways branch out from their parent (branching angle) and the rotation angle between successive bifurcation planes are also included. These data are from the study of two sets of airways computed tomography (CT) images. One CT scan was performed on a human tracheobronchial tree cast and the other on a healthy male volunteer. The airways in the first nine generations of the cast and in the first six conducting generations of the volunteer were measured using a computer‐based algorithm. The data contribute to the knowledge of the lung anatomy. In particular, the spatial structure of the airways is shown to be strongly defined by the central airways with clear angular lobar patterns. Such patterns tend to disappear with a mean gravity, coronal and sagittal angles of 90° in each generation higher than 13–15. The mean branching angle per generation appears independent of the lobe to which the airways belong. Non‐planar geometry at bifurcation is observed with the mean (± SD) bifurcation plane rotation angle of 79 ± 41° (n = 229). This angle appears constant over the generations studied. The data are useful for improving the 3D realism of the conducting airway structure modelling as well as for studying aerosol deposition, flow and biological significance of non‐planar airway trees using analytical and computational flow dynamics modelling.
Shoot damage effects on regeneration of maples (Acer) across an understorey‐gap microenvironmental gradient
Authors: Sipe T. W. , Bazzaz F. A. 
Published: March 2003

Summary

We measured whole‐plant survival, frequency of leader (mainstem terminal bud) damage among survivors and growth responses of intact and damaged juveniles of three Acer species over 3 years along a microenvironmental gradient represented by the understorey and two sizes of artificially created canopy gaps in central Massachusetts, United States of America.
For all species combined, survival decreased while the frequency of leader damage among survivors increased across the gradient of microsite exposure. Acer rubrum L. (red maple) showed the highest survival (65–93%) but also very high leader damage (80–97%). Acer pensylvanicum L. (striped maple) showed fairly high survival (81–93%) in all but the most exposed microsites (24–36%) and had the lowest leader damage overall (17–44%). Acer saccharum Marsh. (sugar maple) was intermediate for both survival (25–86%) and leader damage (55–96%).
Growth differed significantly among sites and species. Both intact and damaged plants showed greater growth in gaps than in understorey, particularly in large gaps. For most growth variables in most microsites, A. pensylvanicum ≥ A. rubrum > A. saccharum when plants were intact, but A. rubrum ≥ A. pensylvanicum > A. saccharum when damaged. Species differences in growth varied among sites, with large gaps producing more pronounced effects than small gaps and understorey for both intact and damaged plants.
Growth recovery was inversely related to leader damage frequency among species, and thus at least partially offset the effects of damage on net growth across the populations.
The microsite‐ and species‐specific responses to leader damage may influence gap regeneration and forest composition. A. pensylvanicum may be favoured by its regrowth advantage over A. rubrum and A. saccharum in the understorey, where damage is likely to occur during prolonged pre‐gap periods. In contrast, A. rubrum shows a decisive advantage over its congeners in regrowth in the centres of large gaps, where the probability of a juvenile tree capturing canopy gap space is highest.
Freestanding lipid bilayers as substrates for electron cryomicroscopy of integral membrane proteins
Authors: Mcalduff D. E. , Heng Y. M. , Ottensmeyer F. P. 
Published: March 2003

SummaryPhospholipid bilayers, 40 Å thick, were generated as electron microscope substrates by submerging copper grids overlaid with holey plastic through a lipid monolayer on a water surface. Previously formed proteoliposomes containing single‐particle membrane proteins in their bilayers were then fused into the newly formed bilayer substrate. To demonstrate this methodology, multi‐drug resistance protein P‐glycoprotein was incorporated into these bilayers and imaged by fixed beam microscopy and scanning transmission electron microscopy.
Homogeneous repair of nuclear genes after experimental stroke
Authors: Moore N. , Okocha F. , Cui J. K. , Liu Philip K. 
Published: March 2003

AbstractThe repair of oxidative DNA lesions (ODLs) in the nucleus of ischemic cortical brain cells was examined following experimentally induced stroke by occluding the right middle cerebral artery and both common carotid arteries for 60–90 min followed by reperfusion in male long‐Evans hooded rats. The control group consisted of sham‐operated animals undergoing the same surgery without vessel occlusion. Using a gene‐specific assay based upon the presence of Escherichia coli Fpg protein‐sensitive sites, we noted that animals with stroke exhibited six and four ODLs per gene in the actin and DNA polymerase‐β genes, respectively. This was increased from one per four copies of each gene in the sham‐operated control (p < 0.01). One half of the initial ODLs was repaired within 30 min, and 83% of them were repaired as early as 45 min of reperfusion. There was no further increase when gene repair was measured again at 2 h of reperfusion. The rates of active repair within 45 min of reperfusion were the same in these two genes (p = 0.103, anova). BrdU (10 mg/kg) was administered via intraperitoneal injection at least one day before surgery. We observed that there was no significant incorporation of BrdU triphosphates into genomic DNA during active repair, but there were significant amounts of BrdU triphosphate in nuclear DNA after active repair. The result indicates that genomic repair of ODLs in the brain did not significantly incorporate BrdU, and the initiation of neurogenesis probably starts after the completion of repair in the brain.
Differential cell surface expression of GABAA receptor α1, α6, β2 and β3 subunits in cultured mouse cerebellar granule cells – influence of cAMP‐activated signalling
Authors: Ives Jane H. , Drewery Debra L. , Thompson Christopher L. 
Published: March 2003

AbstractIn this study we have used mature, primary cultured mouse cerebellar granule cells (CGCs) to initiate our studies on the mechanisms governing neuronal trafficking of GABAA receptors (GABARs). Initially the steady‐state distribution of GABAR α1, α6, β2 and β3 subunits between the cell surface and cell interior was quantified. Cell surface proteins were modified with a membrane‐impermeable cross‐linking agent, bis(sulfosuccinimidyl)suberate (BS3) or the proteolytic enzyme, chymotrypsin. The proportion of unmodified (intracellular) and modified (cell surface) subunits was quantified by immunoblotting. We found that 51% of α6, 74% of α1, and 83% of β2/3 were expressed at the cell surface, thus identifying a sizeable intracellular pool of α6 in contrast to the low levels of intracellular α1 and β2/3. Chronic activation of protein kinase A (PKA) in CGCs in vitro, post‐transcriptionally up‐regulated expression of α1, β2 and β3 but not α6. This was paralleled by an increase in the BZ‐S subtype of [3H]Ro15–4513 binding sites. GABAR α1 was increased at the cell surface and in the cell interior, β2 was increased almost exclusively at the cell surface whilst β3 was increased almost exclusively in the cell interior. The intracellular pool of α6 was not affected. Thus, GABAR subunits are subject to differentially regulated trafficking, affording yet greater scope for GABAR diversity and plasticity.
Neuroprotective properties of cannabinoids against oxidative stress: role of the cannabinoid receptor CB1
Authors: Marsicano Giovanni , Moosmann Bernd , Hermann Heike , Lutz Beat , Behl Christian 
Published: March 2003

AbstractNeuroprotective effects have been described for many can‐nabinoids in several neurotoxicity models. However, the exact mechanisms have not been clearly understood yet. In the present study, antioxidant neuroprotective effects of cannabinoids and the involvement of the cannabinoid receptor 1 (CB1) were analysed in detail employing cell‐free biochemical assays and cultured cells. As it was reported for oestrogens that the phenolic group is a lead structure for antioxidant neuroprotective effects, eight compounds were classified into three groups. Group A: phenolic compounds that do not bind to CB1. Group B: non‐phenolic compounds that bind to CB1. Group C: phenolic compounds that bind to CB1. In the biochemical assays employed, a requirement of the phenolic lead structure for antioxidant activity was shown. The effects paralleled the protective potential of group A and C compounds against oxidative neuronal cell death using the mouse hippocampal HT22 cell line and rat primary cerebellar cell cultures. To elucidate the role of CB1 in neuroprotection, we established stably transfected HT22 cells containing CB1 and compared the protective potential of cannabinoids with that observed in the control transfected HT22 cell line. Furthermore, oxidative stress experiments were performed in cultured cerebellar granule cells, which were derived either from CB1 knock‐out mice or from control wild‐type littermates. The results strongly suggest that CB1 is not involved in the cellular antioxidant neuroprotective effects of cannabinoids.
Photic regulation of l‐arginine uptake in the golden hamster retina
Authors: Sáenz Daniel A. , Cymeryng Cora B. , De Nichilo Analía , Sacca Geraldine B. , Keller Sarmiento María I. , Rosenstein Ruth E. 
Published: March 2003

AbstractOne of the limiting steps in the regulation of nitric oxide (NO) synthesis is the availability of its precursor, l‐arginine, which depends on the presence of a specific uptake system. A characterization of the l‐arginine uptake mechanism in the golden hamster retina was performed. This mechanism was stereospecific, saturable, and monophasic, with an apparent Km of 56.1 ± 2.0 µm and a maximum velocity of 36.0 ± 2.8 pmol/mg prot/min. The basic amino acids l‐lysine and l‐ornithine but not d‐arginine or the nitric oxide synthase inhibitors, Nω‐nitro‐l‐arginine methyl ester and Nω‐nitro‐l‐arginine impaired l‐arginine influx. Preincubation with l‐lysine for 1 h prior to the transport assay significantly stimulated l‐arginine uptake. Saturation studies of l‐arginine uptake performed at 12.00 and 24.00 h indicated a higher value of Vmax at midnight than at midday. When the hamsters were placed under constant darkness or constant light for 48 h and killed at equivalent time points, representing subjective day and subjective night, the differences in l‐arginine influx disappeared. Semiquantitative RT‐PCR analysis showed that the levels of mRNAs for both CAT‐1 and CAT‐2B were significantly higher at midnight than at midday. l‐Arginine significantly increased cGMP accumulation in a time‐dependent manner, with maximal effects during the night. Based on these results, it might be presumed that hamster retinal l‐arginine uptake is regulated by the photic stimulus.
Toward understanding vesicle traffic and the guard cell model
Authors: Blatt Michael R. 
Published: March 2003

SummaryVesicular trafficking and membrane fusion are integral to cell growth and development with SNARE proteins, RabGTPases and their associates implicated in membrane fusion and secretion throughout the plant endomembrane system. Although the overall pattern of function is similar to that of animals and yeast, many aspects of endomembrane organization and vesicle trafficking appear unique to plants, for example, the control of cell and vacuolar expansion, asymmetric growth and cell division. However, the dominant membrane trafficking pathways have yet to be defined. Comparative genomics provide important information about vesicle trafficking elements but assigning biological roles based on sequence similarities is extremely difficult. Cellular and genetic approaches are reviewed here that have allowed visualization of vesicle trafficking in plants, including capacitance and dye methods, imaging and marker techniques, protein interactions and reverse genetics. Stomatal guard cells are discussed as cell models for identifying vesicle trafficking pathways and evidence points to a role for vesicle trafficking in stomatal function. For plants generally, kinetic analyses and biochemical studies suggest that several different pools of vesicles, and possibly different mechanisms for delivery, are available for vesicle traffic between endomembrane compartments and the plasma membrane. Characterizing these pathways, their functions and controls provides a major challenge for the future.
Prevalence of human parvovirus B19 in blood donors as determined by a haemagglutination assay and verified by the polymerase chain reaction
Authors: Hitzler W. E. , Runkel S. 
Published: March 2003

Background and Objectives Transmission of human parvovirus B19 (PV B19) by transfusion of blood and blood products is well documented. Although PV B19 infection is connected with severe complications in some recipients, donor screening is not yet mandatory. In this study the prevalence of PV B19, as detected by a haemagglutination assay (the Human PV B19 Antigen‐Test), was assessed. In addition, the persistence of B19 DNA and the serological status of blood donors was also assessed. The specificity and utility of the Human PV B19 Antigen‐Test for donor screening was investigated and compared with other screening strategies.Materials and Methods The prevalence of PV B19 viraemia was assessed in 28 972 donations from 15 660 remunerated donors by means of the haemagglutination assay. Reactive results were confirmed by the polymerase chain reaction (PCR).Results Overall, 255 donations gave reactive or indeterminate results in the screening assay. Four donations/donors detected by the haemagglutination assay were confirmed as positive for B19 DNA by PCR. Therefore, a frequency was detected of 1 : 7243 B19‐positive donations and 1 : 3915 positive donors. Specificity was determined to be 99·1%. Follow‐up showed the persistence of viraemia in low concentrations for prolonged time‐periods.Conclusion Blood donations with a high level of human PV B19 viraemia can be detected by the haemagglutination assay, which is rapid and easy to perform. The presence of neutralizing antibody may inhibit specific haemagglutination.
A comparison of cellular and humoral immune responses to trichuroid derived antigens in human trichuriasis
Authors: Turner Joseph , Faulkner Helen , Kamgno Joseph , Else Kathryn , Boussinesq Michel , Bradley Janette E. 
Published: March 2003

SummaryIndividuals, residing in a region highly endemic for Trichuris trichiura, were examined for cytokine and proliferative responses to T. trichiura worm homogenate (TtAg), T. trichiura excretory/secretory products (TtES) and the equivalent antigenic preparations from the murine whipworm, Trichuris muris. Serum antibody levels against TtAg, T. muris worm homogenate and T. muris ES products were also studied. Measurable levels of immunoglobulin (Ig)G1, IgG4, IgA and IgE against T. muris antigens were detected, indicating a degree of conservation of epitopes between antigens derived from both species. Although levels of interleukin (IL)‐4, IL‐10, IL‐13, tumour necrosis factor (TNF)‐α and proliferative responses produced were comparable between homogenate antigens of either species and ES antigens of either species, a markedly different cellular response was observed in cultures stimulated with homogenate antigens compared to ES antigens. ES antigens preferentially induced IL‐10 (P > 0·001) and TNF‐α (P > 0·001) production, whereas levels of IL‐4 (P > 0·001), IL‐13 (P > 0·001) and proliferative responses (P > 0·001) were greater in cultures stimulated with whole worm extracts. Our findings suggest that T. muris preparations could be used as an alternative to T. trichiura proteins as a source of antigens in ex vivo cultures and that ES products stimulate a distinct immune response compared to somatic antigens.
Effects of instrumentation, irrigation and dressing with calcium hydroxide on infection in pulpless teeth with periapical bone lesions
Authors: Peters L. B. , Van Winkelhoff A.‐J. , Buijs J. F. , Wesselink P. R. 
Published: March 2003

AbstractAim The aim of this study was to evaluate the fate of microorganisms in root canals of teeth with infected pulps and periapical bone lesions with and without the use of calcium hydroxide medication.Methodology Endodontic samples were cultured and microorganisms were counted and identified in 43 teeth before (sample 1) and after (sample 2) treatment during the first visit and before (sample 3) and after (sample 4) treatment during the second visit. In the first visit teeth were instrumented and half of the teeth were filled with a thick slurry of calcium hydroxide in sterile saline. The other teeth were obturated with gutta‐percha and AH‐26 sealer. After 4 weeks the teeth with calcium‐hydroxide were accessed again and after microbiological sampling they were obturated with gutta‐percha and AH‐26 sealer.Results The mean total colony forming unit (CFU) counts of positive samples dropped significantly as a result of canal preparation during the first visit from 1.0 × 106 to 1.8 × 103 (between samples 1 and 2) but increased to 9.3 × 103 in the period between the two visits (sample 2 and 3). There was no difference in mean total CFU counts of positive samples between the end of the first (sample 2) and the end of the second visit (sample 4). The most frequently isolated species were Prevotella intermedia, Capnocytophaga spp., Actinomyces odontolyticus, Propionibacterium acnes and Peptostreptococcus micros.Conclusions Although a calcium hydroxide paste was placed in the prepared canals, the number of positive canals had increased in the period between visits. However, the number of microorganisms had only increased to 0.93% of the original number of CFU (sample 1). It is concluded that a calcium hydroxide and sterile saline slurry limits but does not totally prevent regrowth of endodontic bacteria.
Preservative systems containing essential oils in cosmetic products
Authors: Maccioni A. M. , Anchisi C. , Sanna A. , Sardu C. , Dessì S. 
Published: March 2003

SynopsisThe aim of this study was to evaluate the antimicrobial activity of selected essential oils (Laurus nobilis, Eucalyptus globulus and Salvia officinalis), both alone and in combination, in cosmetic preparations characterized by an increasing risk of microbial contamination, i.e. an O/W skin cream, a hydrogel and a non‐alcoholic hydrolyte. Their potential synergistic effect in combination with the usual cosmetic preservatives at low concentrations (up to 200‐fold less than usual) was also investigated.