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Deeper Areas (deeper + area)
Selected AbstractsHabitat and food choice of Arctic charr in Linnévatn on Spitsbergen, Svalbard: the first year-round investigation in a High Arctic lakeECOLOGY OF FRESHWATER FISH, Issue 1 2007M.-A. Svenning Abstract,,, Habitat and diet of Arctic charr Salvelinus alpinus (L.) were studied by monthly sampling from late autumn to early summer in Linnévatn, Svalbard (78°3,N, 13°50,E). This is the first year-round study of a population of charr in the High Arctic, with samples being taken every 5,7 weeks. The ice cover lasted for more than 9 months, from mid-October to late July, with the greatest thickness in mid-May. Although most charr occupied the littoral zone during winter, the highest densities in April and October were found in the deeper areas (20 m) of the lake. The fish fed at all times of the year, but the number of stomachs with food and the stomach-filling indices were lowest during the darkest part of the season. The diet of smaller charr (<15 cm) varied strongly with season, showing a dominance of zooplankton in late autumn and chironomids in winter (larvae) and summer (pupae). The food choice was in accordance with the density of food items available. Larger fish (,15 cm) were mostly cannibalistic during the entire year. [source] Differentiation and migration of astrocytes in the spinal cord following dorsal root injury in the adult ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2003Elena N. Kozlova Abstract Nerve fibre degeneration in the spinal cord is accompanied by astroglial proliferation. It is not known whether these cells proliferate in situ or are recruited from specific regions harbouring astroglial precursors. We found cells expressing nestin, characteristic of astroglial precursors, at the dorsal surface of the spinal cord on the operated side from 30 h after dorsal root injury. Nestin-expressing cells dispersed to deeper areas of the dorsal funiculus and dorsal horn on the operated side during the first few days after injury. Injection of bromodeoxyuridine (BrdU) 2 h before the end of the experiment, at 30 h after injury, revealed numerous BrdU-labelled, nestin-positive cells in the dorsal superficial region. In animals surviving 20 h after BrdU injection at 28 h postlesion, cells double-labelled with BrdU and nestin were also found in deeper areas. Labeling with BrdU 2 h before perfusion showed proliferation of microglia and radial astrocytes in the ventral and lateral funiculi on both sides of the spinal cord 30 h after injury. Nestin-positive cells coexpressed the calcium-binding protein Mts1, a marker for white matter astrocytes, in the dorsal funiculus, and were positive for glial fibrillary acidic protein (GFAP), but negative for Mts1 in the dorsal horn. One week after injury the level of nestin expression decreased and was undetectable after 3 months. Taken together, our data indicate that after dorsal root injury newly formed astrocytes in the degenerating white and grey matter first appear at the dorsal surface of the spinal cord from where some of them subsequently migrate ventrally, and differentiate into white- or grey-matter astrocytes. [source] Transient Leakance and Infiltration Characteristics during Lake Bank FiltrationGROUND WATER, Issue 1 2009B. Wiese Infiltration capacity of bank filtration systems depends on water extraction and hydraulic resistance of the bed sediments. Lakebed hydraulics may be especially affected by clogging, which is dependent on settlement of fine particles, redox potential, and other factors. In the field, most of these processes are difficult to quantify, and thus, when calculating response to pumping the water flux across the sediment surface is assumed to be linearly dependent on the hydraulic gradient. However, this assumption was not adequate to describe conditions at a bank filtration site located at Lake Tegel, Berlin, Germany. Hence, we first assumed the leakage coefficient (or leakance) is spatially distributed and also temporally variant. Furthermore, observations show that the leakance is considerably higher in shallow than in deeper areas; hence, leakance was assumed to be dependent on the existence and thickness of an unsaturated zone below the lake. The proposed explanation of spatial and temporal variability in leakance involves a hypothesis for redox dependent and reversible biogeochemical clogging, supported by geochemical observations in surface water and ground water. Four leakance approaches are implemented in the ground water flow code MODFLOW2000 and calibrated by inverse modeling using the parameter estimation software PEST. These concepts are evaluated by examining the fit to the hydraulic heads, to infiltration measurements, transport modeling results, and considering the degrees of freedom due to the number of calibration parameters. The leakage concept based on the assumption of the influence of an unsaturated zone on clogging processes best explains the field data. [source] The amount of newly formed bone in sinus grafting procedures depends on tissue depth as well as the type and residual amount of the grafted materialJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2005Zvi Artzi Abstract Objectives: Bone replacement substitutes are almost unavoidable in augmentation procedures such as sinus grafting. The objective of the present study was to evaluate the osteoconductive capability of two different scaffold fillers in inducing newly formed bone in this procedure. Material and Methods: Sinus floor augmentation and implant placement were carried out bilaterally in 12 patients. Bovine bone mineral (BBM) was grafted on one side and , -tricalcium phosphate (, -TCP) on the contralateral side. Both were mixed (1:1 ratio) with autogenous cortical bone chips harvested from the mandible by a scraper. Hard tissue specimen cores were retrieved from the augmented sites (at the previous window area) at 12 months. Decalcified sections were stained with haematoxylin,eosin and the fraction area of new bone and filler particles was measured. In addition to the effect of the filler on new bone formation, the latter was tested to determine whether it correlated with the tissue depth and residual amount of the grafted material. Results: Bone area fraction increased significantly from peripheral to deeper areas at both grafted sites in all cores: from 26.0% to 37.7% at the , -TCP sites and from 33.5% to 53.7% at the BBM-grafted sites. At each depth the amount of new bone in BBM sites was significantly greater than that in TCP sites. However, the average area fraction of grafted material particles was similar in both fillers and all depth levels (, -TCP=27.9,23.2% and BBM=29.2,22.6%, NS). A significant negative correlation was found between bone area fraction and particle area fraction at the middle (p=0.009) and deep (p=0.014) depths in the , -TCP sites, but not at the BBM sites. Conclusion: At 12 months post-augmentation, the two examined bone fillers, , -TCP and BBM, promoted new bone formation in sinus grafting but the amount of newly formed bone was significantly greater in BBM-grafted sites. However, both exhibited similar residual grafted material area fraction at this healing period. This could imply that BBM possesses better osteoconductive properties. [source] Ultrastructural study of the precursor to fungiform papillae prior to the arrival of sensory nerves in the fetal ratJOURNAL OF MORPHOLOGY, Issue 3 2001Shin-ichi Iwasaki Abstract The structure of precursors to fungiform papillae without taste buds, prior to the arrival of sensory nerve fibers at the papillae, was examined in the fetal rat on embryonic day 13 (E13) and 16 (E16) by light and transmission electron microscopy in an attempt to clarify the mechanism of morphogenesis of these papillae. At E13, a row of rudiments of fungiform papillae was arranged along both sides of the median sulcus of the lingual dorsal surface, and each row consisted of about 10 rudiments. There was no apparent direct contact between papillae rudiments and sensory nerves at this time. Bilaterally towards the lateral side of the tongue, adjacent to these first rudiments of fungiform papillae, a series of cord-like invaginations of the dorsal epithelium of the tongue into the underlying connective tissue, representing additional papillary primordia parallel to the first row, was observed. The basal end of each invagination was enlarged as a round bulge, indented at its tip by a mound of fibroblasts protruding into the bulge. At E16 there was still no apparent direct contact between rudiments of fungiform papillae and sensory nerves. Each rudiment apically contained a spherical core of aggregating cells, which consisted of a dense assembly of large, oval cells unlike those in other areas of the lingual dorsal epithelium. The differentiation of these aggregated cells was unclear. The basal lamina was clearly recognizable between the epithelium of the rudiment of fungiform papillae and the underlying connective tissue. Spherical structures, which appeared to be sections of the cord-like invaginations of the lingual epithelium that appeared on E13, were observed within the connective tissue separated from the dorsal lingual epithelium. Transverse sections of such structures revealed four concentric layers of cells: a central core, an inner shell, an outer shell, and a layer of large cells. Bundles of fibers were arranged in the central core, and the diameters of bundles varied somewhat depending on the depth of the primordia within the connective tissue and their distance from the median sulcus. Ultrastructural features of cells in the outer shell differed significantly in rudiments close to the lingual epithelium as compared to those in deeper areas of connective tissue. Around the outer shell there was a large-cell layer consisting of one to three layers of radially elongated, oval cells that contained many variously sized, electron-dense, round granules. Large numbers of fibroblasts formed dense aggregates around each spherical rudiment, and were separated by the basal lamina from the large-cell epithelial layer. Progressing from deep-lying levels of the rudiments of the papillae to levels close to the lingual surface epithelium, the central core, inner shell, and outer shell gradually disappeared from the invaginated papillary cords. J. Morphol. 250:225,235, 2001. © 2001 Wiley-Liss, Inc. [source] ORIGINAL ARTICLE: Phenotypic Characterization of Macrophages in the Endometrium of the Pregnant CowAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2009Lilian J. Oliveira Problem, Macrophages are recruited in large number to the interplacentomal endometrium of the cow during pregnancy. We evaluated whether endometrial macrophages also accumulate in placentomal regions of endometrium during pregnancy and whether endometrial macrophages are regionally differentiated. Method of study, Interplacentomal endometrium and placentomes were subjected to dual-color immunofluorescence using CD68 as a pan-macrophage marker. Results, CD68+ cells were abundant in stroma of the interplacentomal endometrium and caruncular septa of the placentomes. CD68+ cells were not present in fetal villi of the placentomes or in the interplacentomal chorion. Regardless of location, the majority of CD68+ cells also expressed CD14. In interplacentomal endometrium, CD68+CD11b+ cells were present in deeper areas of the stroma but not in shallow endometrial stroma. In caruncular septa of the placentome, CD68+ cells were negative for CD11b. CD68+ cells in the interplacentomal endometrium were negative for MHC class II while most CD68+ cells in caruncular septa were positive for MHC class II. Conclusion, CD68+CD14+ macrophages present in the stroma of the interplacentomal endometrium and caruncular septa of the placentome are regionally differentiated with regard to expression of CD11b and MHC class II. [source] | |||||||||||||