Objective Type VI collagen is a major component of the pericellular matrix compartment in articular cartilage and shows severe alterations in osteoarthritic cartilage degeneration. In this study, we ...analysed the exact localization of type VI collagen in its relationship to the chondrocyte and the (inter)territorial cartilage matrix. Additionally, we were interested in its ultrastructural appearance in normal and osteoarthritic cartilage.
Design Distribution and molecular appearance was investigated by conventional immunostaining, by multilabeling confocal scanning microscopy, conventional transmission, and immunoelectron microscopy.
Results Our analysis confirmed the pericellular concentration of type VI collagen in normal and degenerated cartilage. Type VI collagen formed an interface in between the cell surface and the type II collagen network. The type VI collagen and the type II collagen networks appeared to have a slight physical overlap in both normal and diseased cartilage. Additionally, some epitope staining was observed in the cell-associated interterritorial cartilage matrix, which did not appear to have an immediate relation to the type II collagen fibrillar network as evaluated by immunoelectron microscopy.
In osteoarthritic cartilage, significant differences were found compared with normal articular cartilage: the overall dimension of the lacunar volume increased, and a significantly increased type VI collagen epitope staining was observed in the interterritorial cartilage matrix. Also, the banded isoform of type VI collagen was found around many chondrocytes.
Conclusions Our study confirms the close association of type VI collagen with both, the chondrocyte cell surface and the territorial cartilage matrix. They show severe alterations in type VI collagen distribution and appearance in osteoarthritic cartilage. Our immunohistochemical and ultrastructural data are compatible with two ways of degradation of type VI collagen in osteoarthritic cartilage: (1) the pathologically increased physiological molecular degradation leading to the complete loss of type VI collagen filaments from the pericellular chondrocyte matrix and (2) the transformation of the fine filaments to the band-like form of type VI collagen. Both might implicate a significant loss of function of the pericellular microenvironment in osteoarthritic cartilage. Copyright 2002 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.
Visual habit formation in monkeys, assessed by concurrent visual discrimination learning with 24-h intertrial intervals (ITI), was found earlier to be impaired by removal of the inferior temporal ...visual area (TE) but not by removal of either the medial temporal lobe or inferior prefrontal convexity, two of TE's major projection targets. To assess the role in this form of learning of another pair of structures to which TE projects, namely the rostral portion of the tail of the caudate nucleus and the overlying ventrocaudal putamen, we injected a neurotoxin into this neostriatal region of several monkeys and tested them on the 24-h ITI task as well as on a test of visual recognition memory. Compared with unoperated monkeys, the experimental animals were unaffected on the recognition test but showed an impairment on the 24-h ITI task that was highly correlated with the extent of their neostriatal damage. The findings suggest that TE and its projection areas in the ventrocaudal neostriatum form part of a circuit that selectively mediates visual habit formation.
The objective of this paper is to contribute to the development of sequence stratigraphic models for extensive epicontinental carbonate systems deposited over cratonic areas. Epicontinental ...carbonates of the SW German Upper Jurassic were analysed in terms of microfacies, sedimentology and sequence stratigraphy based on 2.5 km of core, 70 borehole gamma ray logs and 24 quarries. Facies analysis revealed six major facies belts across the deeper parts of the carbonate ramp, situated generally below fair-weather wave base, and mostly below average storm wave base but in the reach of occasional storm events. Observed stratigraphic patterns differ in some aspects from widely published sequence stratigraphic models:
1.
Elementary sedimentary cycles are mostly more or less symmetrical and are, thus, referred to as “genetic sequences” or “genetic units” AAAPG Bull. 55 (1971) 1137; Frazier, D.E., 1974. Depositional episodes: their relationship to the Quaternary stratigraphic framework in the northwestern portion of the Gulf Basin. University of Texas, Austin, Bureau of Economic Geology Geologicalo Circular 71-1; AAPG Bull. 73 (1989) 125; Galloway, W.E., Hobday, D.K., 1996. Terrigenous Clastic Depositional Systems. 489 pp., Springer; Cross, T.A., Baker, M.R., Chapin, M.S., Clark, M.S., Gardner, M.H., Hanson, M.S., Lessenger, M.A., Little, L.D., McDonough, K.J., Sonnenfeld, M.D., Valasek, D.W., Williams, M.R., Witter, D.N., 1993. Applications of high-resolution sequence stratigraphy to reservoir analysis. Edition Technip 1993, 11–33; Bull. Cent. Rech. Explor. Prod. Elf-Aquitaine 16 (1992) 357; Homewood, P., Mauriaud, P., Lafont, F., 2000. Best practices in sequence stratigraphy. Elf EP Mem. 25, 81 pp.; Homewood, P., Eberli, G.P., 2000. Genetic stratigraphy on the exploration and production scales. Elf EP Mem. 24, 290 pp., in contrast to the asymmetrical, shallowing-upward “parasequences” of the EXXON approach.
2.
Neither sequence boundaries nor maximum flooding surfaces could be clearly delineated. Cycle boundaries are generally not represented by sharp stratal surfaces but are always transitional and, thus, referred to as “turnarounds” Nor. Pet. Soc. Spec. Publ. 8 (1998) 171.
Several types of genetic sequences were delineated. Both major types of facies and sequences show characteristic gamma ray log signatures. Based on the cycle stacking and the gamma ray patterns, a hierarchy of sequences was recognized, probably driven in part by 100,000- and 400,000-year Milankovitch signals. The cyclicity allowed regional correlations across various depositional environments such as sponge–microbial bioherms and coeval basins. The basin-wide correlation revealed evidence for a subtle clinoform-type stratigraphic architecture along very gentle slopes, rather than a so far assumed simple “layer cake” pattern.
The Middle Triassic Upper Muschelkalk carbonate ramp deposits in SW-Germany provide an excellent ‘laboratory scale’ analogue for vast epeiric basin fills such as in the Middle East. The Upper ...Muschelkalk and the entire Mesozoic overburden in SW-Germany were deposited on a complex mosaic of three major, differentially subsiding Variscan paleo-tectonic blocks: the Rhenohercynian, Saxothuringian and Moldanubian - subtly influencing the depositional facies pattern for long periods of time. This study is based on detailed sedimentological logs of 41 boreholes and surface outcrop sections and 39 gamma-ray logs, lithofacies analysis, and a 1-D and 2-D sequence stratigraphic analysis leading to a regional correlation integrating sequence architecture and marker beds. Using the subsurface 3D modelling tool Petrel, two nested geocellular reservoir models were generated: (i) a basin scale (201.5 × 325 km) Lithofacies Associations (LFA) model based on truncated Gaussian simulation (TGS); (ii) a field scale (50 × 50 km) Lithofacies Types (LFT) model based on sequential indicator simulation (SIS). The integrated 3D facies models reveal landward facies retrogradation with patchy isolated shoal bodies during the transgressive hemisequence and basinward facies progradation with well-connected large shoals within the regressive hemisequence. Models combined with structural maps show the influence of large Variscan block segments and smaller scale internal structural elements on the distribution, and the size of reservoir analogues, both shoal- and dolomite bodies. This relationship offers a new tool for exploration in epeiric carbonates using deep-seated paleo-tectonic patterns for the prediction of both hydrocarbon and geothermal reservoirs.
Outcrop analogue investigations contribute to the understanding of the architecture and behaviour of subsurface hydrocarbon reservoirs. This study was designed to provide input for static reservoir ...modelling of shoal bodies on carbonate ramps.
We investigated an oolitic and shelly carbonate shoal of Late Muschelkalk (late Ladinian) age, about 30 km long and 15 km wide, exposed in a series of quarries in southern Germany. The dimensions of this shoal body correspond to both modern analogues in the Persian Gulf and to oilfields in the Middle East.
Fifteen outcrop locations were chosen to cover the entire shoal. A regional correlation based on facies, sequence analysis and outcrop gamma‐ray logs was used as a framework for mapping the distribution of shoal (i. e. reservoir) facies and associated reservoir properties.
Three major depositional environments were recognized: foreshoal, shoal and backshoal. In each environment, specific vertical facies successions composed of thick shallowing‐upward units and thin deepening‐upward units forming metre‐scale cycles were deposited. These small‐scale cycles are stacked and form large‐scale shallowing and deepening trends. Shoal facies developed preferentially in the regressive parts of small‐scale cycles and were found to be laterally continuous over distances of at least several kilometres.
Porous intervals within the shoal facies are concentrated along the tops of the small‐scale shallowing‐upward cycles. The porous intervals in successive small‐scale cycles increase in thickness and in absolute values of porosity upwards through the large‐scale shallowing trend. Separate vug pore types are characterized by relatively low permeabilities (0 to about 10 mD) in spite of the high porosity (up to 20%). The combined occurrence of separate vug and interparticle porosity leads to higher permeabilities (tens of mD).
Isolines of porosity, permeability and net/gross follow the contours of the carbonate shoal complex. The highest values of porosity appear more or less at the centre of the shoal, while the highest values of permeability are found at the shoal margins. The distribution of maximum porosity and maximum permeability zones are thus controlled by the cyclic seaward‐stepping and landward‐stepping of the shoal body.
The systematic variations in extent, stacking pattern and related petrophysical characteristics of the carbonate shoal bodies may be used for modelling shoal reservoirs in producing oilfields.
In articular cartilage, type VI collagen is concentrated in the pericellular matrix compartment. During protein synthesis and processing at least the α3(VI) chain undergoes significant ...posttranslational modification and cleavage. In this study, we investigated the processing of type VI collagen in articular cartilage. Immunostaining with a specific polyclonal antiserum against the C5 domain of α3(VI) showed strong cellular staining seen in nearly all chondrocytes of articular cartilage. Confocal laser-scanning microscopy and immunoelectron microscopy allowed localization of this staining mainly to the cytoplasm and the immediate pericellular matrix. Double-labeling experiments showed a narrow overlap of the C5 domain and the pericellular mature type VI collagen. Our results suggest that at least in human adult articular cartilage the C5 domain of α3(VI) collagen is synthesized and initially incorporated into the newly formed type VI collagen fibrils, but immediately after secretion is cut off and is not present in the mature pericellular type VI matrix of articular cartilage.
We describe the rare entity of an intraosseous meningioma arising in the mandible. The meningioma was found incidentally in an asymptomatic adult patient on dental radiography, mimicking other ...cystic-appearing jaw masses. The CT and MR imaging features of mandibular meningioma are reviewed with reference to prior published descriptions of this unusual entity.
The objective of this study was to determine whether collagen type II breakdown products in synovial fluid (SF), detected by an enzyme-linked immunoassay, represent a useful marker for early events ...in osteoarthritis (OA) in the rabbit medial meniscectomy model.
Complete medial meniscectomy was performed on the right knee joints of 32 rabbits. Balanced groups of rabbits were then sacrificed at 2, 4, 8, and 12 weeks post-surgery. An additional 8 unoperated and 11 sham-operated animals served as controls. SF lavages were performed on right and left knee joints of the same animals at sacrifice. The proteolytic epitope of type II collagen was monitored using an enzyme-linked immunoassay.
Macroscopically visible surface fibrillation and focal erosions appeared as early as 2 weeks after meniscectomy in the femorotibial joint (
P
<
0.01). OA developed gradually during the later observation period, and then predominantly on the medial tibial plateau and medial femur. Significant histological alterations in cartilage, including a loss of proteoglycans, surface irregularities, and clefts, were detected at 2 weeks after meniscectomy (
P
<
0.01). Collagen type II epitope levels in SF lavage samples were elevated peaking at 2 weeks after meniscectomy (
P
<
0.02). Levels decreased at later time points, but they were still raised at 12 weeks (
P
≤
0.05). Highly significant correlations were found between the SF collagen type II epitope levels and the macroscopic and microscopic scoring results (Spearman rho correlation coefficient, macroscopy—collagen type II epitope
r
=
0.222,
P
=
0.025; microscopy—collagen type II epitope
r
=
0.436,
P
≤
0.01).
In this rabbit model of medial meniscectomy, levels of type II collagen fragments in SF appear to provide a useful marker of the early degenerative changes.
Central European Upper Jurassic sponge-microbial “reefs” are commonly regarded as compact, massive and homogenous facies bodies. A continuous study of borehole cores from SW Germany clearly shows a ...very systematic architecture of these “reefs” built by sedimentary cycles of various hierarchical levels. Altogether five orders of cycles can be distinguished: decimeter-scale microcycles building meter-scale mesocycles, which in turn are stacked to form several-meter thick macrocycles. These high-frequency cycles in turn are parts of basin-wide medium-scale and large-scale cycles reported in a previous paper. This paper documents the high-frequency micro-, meso- and macrocycles. Microcycles (0.1–0.8 m thick) usually have a sharp erosional base covered by reworked sponges, shells and intraclasts, interpreted as storm events. These bioclastic layers are colonised by a succession of thrombolitic and stromatolitic microbialites. Successive microcycles form distinct stacks that record gradually increasing and decreasing depositional energy, thus defining mesocycles (0.5–4 m thick). Several mesocycles construct macrocycles (3–25 m). The cycle stacking patterns were analysed by means of facies-proportion-diagrams. The dominant microscale cyclicity records changes in water agitation, possibly caused by fluctuating storm wave base. The sponge-microbial mounds could probably build up just to average storm wave base. Within the cycles of larger hierarchical levels the successive smaller-scale cycles show systematic trends in their symmetry and in thickness. This may be caused by variations in the ratio of accomodation space (and associated energy level) to carbonate production. External reef geometries (progradation, aggradation, retrogradation, condensation) can be related to internal cycle stacking patterns. To approximate the duration of the high-frequency cycles two different approaches were used. Firstly, the duration of cycles was determined with the help of published chronostratigraphic time scales. Secondly, cycle duration was estimated using published microbial reef growth rates. Both approximations result in ca. 0.4 Ma for the medium-scale cycles and 0.1 Ma for the macrocycles. Both are regionally correlatable, thus appear to be allocyclic in nature and probably are Milankovitch-driven. In contrast, the microcycles are only locally correlatable and thus indicate an autocyclic (storm-induced) nature. This study poses the question if not more of the apparently homogenous “reef bodies” of other settings and geological ages may possibly also show internal high-frequency cycles.
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