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  • 1
    Electronic Resource
    Electronic Resource
    Photosynthesis under osmotic stress (1981)
    Springer
    Planta 153 (1981), S. 430-435 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast ; Photosynthesis (stress recovery) ; Protoplast ; Spinacia ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reversibility of the inhibition of photosynthetic reactions by water stress was examined with four systems of increasing complexity—stromal enzymes, intact chloroplasts, mesophyll protoplasts, and leaf slices. The inhibition of soluble chloroplast enzymes by high solute concentrations was instantly relieved when solutes were properly diluted. In contrast, photosynthesis was not restored but actually more inhibited when isolated chloroplasts exposed to hypertonic stress were transferred to conditions optimal for photosynthesis of unstressed chloroplasts. Upon transfer, chloroplast volumes increased beyond the volumes of unstressed chloroplasts, and partial envelope rupture occurred. In protoplasts and leaf slices, considerable and rapid, but incomplete restoration of photosynthesis was observed during transfer from hypertonic to isotonic conditions. Chloroplast envelopes did not rupture in situ during water uptake. It is concluded that inhibition of photosynthesis by severe water stress is at the biochemical level brought about in part by reversible inhibition of chloroplast enzymes and in part by membrane damage which requires repair mechanisms for reversibility. Both soluble enzymes and membranes appear to be affected by the increased concentration of internal solutes, which is caused by dehydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394981
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  • 2
    Electronic Resource
    Electronic Resource
    Photosynthesis of isolated chloroplasts and protoplasts under osmotic stress (1981)
    Springer
    Planta 151 (1981), S. 375-380 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast volume ; Photosynthesis and chloroplast volume ; Spinacia ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Isolated intact spinach chloroplasts respond to changes of the sorbitol concentration of the suspending medium as near-perfect osmometers within a large range of osmotic potentials. Under isotonic conditions (π=9–10 bar), their average osmotic volume is 24 μm3 and the total volume 36 μm3. The osmotic volume can be increased to 63 μm3 by lowering the sorbitol concentration until a critical osmotic potential of π=4 bar is reached. Below that value chloroplasts rupture. Between 10 bar and 4 bar, volume changes are reversible. 2. Increasing the chloroplast volume above 24 μm3 causes inhibition of photosynthesis, with 50% inhibition occurring at an osmotic potential of π=5–6 bar. This corresponds to an osmotic volume of 45–55 μm3. Depending on the duration of hypotonic treatment, inhibition of photosynthesis is more or less reversible. 3. Between 4 and 10 bar, the chloroplast envelope exhibits a very low permeability for ferricyanide, many metabolites, and soluble stroma proteins. 4. Electron transport is not inhibited by swelling of chloroplasts. Also, the ATP/ADP-ratio remains unchanged. 5. The solute concentration in the chloroplasts appears to be optimal for photosynthesis at 10 bar. Increasing the chloroplast volume causes inhibition of photosynthesis by dilution effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393294
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  • 3
    Electronic Resource
    Electronic Resource
    Das Klarzellchondrosarkom (2000)
    Springer
    Der Pathologe 21 (2000), S. 449-455 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Knochentumoren ; Klarzellchondrosarkom ; Histologie ; Differenzialdiagnose ; Keywords Bone tumors ; Clear-cell chondrosarcoma ; Histology ; Differential diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Clear-cell chondrosarcoma is a rare, low-malignant bone tumor. The lesion most commonly occurs in adults, generally in the 3rd or 4th decade. Clear-cell chondrosarcoma has a predilection for the epiphyses of long tubular bones, particularly the femoral head. Radiologically, it is a sharply defined radiolucent lesion. Histologically, it is characterized by large tumor cells with distinct boundaries and a clear cytoplasm. In addition to areas of conventional chondrosarcoma, there are partially mineralized trabecular osteoid formations. On the basis of 16 cases of clear-cell chondrosarcoma, we present the observations of the Hamburg Bone Tumor Register. The cases were examined according to age distribution, location, and radiological and pathomorphological criteria. The proximal femur was the most frequent location; rare manifestations in the rib, os ilium, and distal phalanx of the hand were also present. In 50% of the cases high-malignant osteosarcoma or conventional chondrosarcoma was considered. In addition to the epiphysis of the proximal femur, clear-cell chondrosarcoma can also involve other, rather unusual sites in the skeleton. Knowledge of the histomorphology of this tumor is therefore of crucial importance for the diagnosis.
    Notes: Zusammenfassung Das Klarzellchondrosarkom ist ein seltener niedrigmaligner Knochentumor. Betroffen sind v. a. Patienten in der 3. und 4. Lebensdekade. Bevorzugte Lokalisation sind die Epiphysen langer Röhrenknochen, insbesondere der Femurkopf. Radiologisch imponiert es meist als eine epiphysär gelegene, scharf begrenzte lytische Läsion. Histologisch charakteristisch sind die großen Tumorzellen mit deutlichen Zellgrenzen und einem hellen Zytoplasma. Daneben finden sich auch Areale mit dem histologischen Bild eines konventionellen Chondrosarkoms sowie unterschiedlich breite, z. T. mineralisierte trabekuläre Osteoidformationen. Anhand von 16 Fällen mit Klarzellchondrosarkom werden die Erfahrungen und Beobachtungen des Hamburger Knochentumor-Registers dargestellt. Die Fälle wurden nach Altersverteilung, Lokalisation sowie radiologischen und pathomorphologischen Kriterien untersucht. Das Hauptmanifestationsalter lag innerhalb der 5.–7. Lebensdekade. Das proximale Femur stellte den Hauptlokalisationsort dar. Daneben fanden sich auch eher seltene Manifestationen im Bereich der Rippe, Os ilium und Grundphalanx der Hand. In 50% der Fälle wurde auswärtig zunächst differenzialdiagnostisch ein hochmalignes Osteosarkom oder ein Chondrosarkom diskutiert. Da das Klarzellchondrosarkom außer in der Epiphyse des proximalen Femurs auch an anderen, eher ungewöhnlichen Stellen des Skeletts auftreten kann, ist die Kenntnis der Histomorphologie dieses Tumors von entscheidender Bedeutung für die Diagnosefindung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920000417
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  • 4
    Electronic Resource
    Electronic Resource
    Das periostale Osteosarkom Histologische Charakteristika, Präparationstechnik, Wachstumsmuster und Differentialdiagnose* (1996)
    Springer
    Der Pathologe 17 (1996), S. 86-91 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Periostales Osteosarkom ; Histologie ; Präparation ; Grading ; Key words Periosteal osteosarcoma ; Histology ; Preparation ; Grading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Periosteal osteosarcoma is a distinct bone tumor entity with characteristic morphological features within the group of juxtacortical osteosarcoma. Periosteal osteosarcoma is predominantly located in the long tubular bones, especially in the tibia and femur and is situated on the outer circumference of the tumor-bearing bone (saucerization phenomenon). In contrast to parosteal osteosarcoma, periosteal osteosarcoma is less differentiated and is believed to have a worse prognosis. In this work the histological features are described with predominantly chondroblastic differentiation of 14 cases with periosteal osteosarcoma. A horizontal preparation technique of periosteal osteosarcoma specimens allows comparison with computed tomography and is the optimal method to detect an invasion of the medullary cavity. Further studies are necessary to clarify if neoadjuvant chemotherapy could improve the prognosis of certain patients.
    Notes: Zusammenfassung Das periostale Osteosarkom stellt eine eigene Entität dar, so daß der Tumor von der Gruppe der juxtakortikalen Osteosarkome eindeutig abgegrenzt werden sollte. Der Tumor tritt überwiegend an den langen Röhrenknochen, speziell Tibia und Femur auf. Er ist durch ein breitbasiges Aufsitzen an der äußeren Circumferenz des tumortragenden Skelettabschnittes charakterisiert (Saucieren-Muster). Im Gegensatz zum parossalen Osteosarkom ist das periostale Osteosarkom niedriger differenziert und hat offenbar eine schlechtere Prognose. Die histologischen Kriterien mit einer überwiegend chondroiden Differenzierung werden anhand von 14 Fällen eigener Beobachtung beschrieben. Der horizontalen Präparation von Tumorresektaten kommt eine besondere Bedeutung im Vergleich zu den bildgebenden Verfahren und zur Erfassung von Markraumeinbrüchen zu. Es gilt in zukünftigen Studien zu klären, bei welchen Patienten mit einer neoadjuvanten Chemotherapie die Prognose verbessert werden kann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050140
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  • 5
    Electronic Resource
    Electronic Resource
    Das Chondromyxoidfibrom Morphologische Variationsbreite, Lokalisation, Häufigkeit, radiologische Kriterien und Differentialdiagnose (1999)
    Springer
    Der Pathologe 20 (1999), S. 224-229 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Knochentumoren ; Chondromyxoidfibrom ; Histologie ; Key words Bone tumors ; Chondromyxoid fibroma ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Chondromyxoid fibroma is a rare benign bone tumor, accounting for less than 1% of all bone tumors. The peak age incidence is the second and third decade of life. Chondromyxoid fibrom occurs in the metaphyseal parts of the major tubular bones, predominantly of the lower extremity. Roentgenograms show, in most cases, a well-demarcated radiolucent lesion. The classic histological feature of a chondromyxoid fibroma is stellate or spindle-shaped cells arranged in lobules in a myxoid or chondroid background. Analysis of 40 chondromyxoid fibromas demonstrates the morphological variation of this tumor. Cases were examined for age distribution, localization, and radiological and histological features. In 85% we found the typical histomorphological pattern. Recurrence rate was 12.5%. In four cases the appearance was uncharacteristic and differentiation from other tumors such as chondroblastoma or chondrosarcoma was quite difficult. By adhering to strict histomorphological criteria, definite diagnosis of chondromyxoid fibroma can be made in most cases.
    Notes: Zusammenfassung Das Chondromyxoidfibrom ist ein seltener gutartiger Knochentumor. Seine Häufigkeit beträgt weniger als 1% aller primären Knochentumoren. Das Hauptmanifestationsalter ist die 2. und 3. Lebensdekade. Der Tumor ist überwiegend in der Metaphyse langer Röhrenknochen lokalisiert, insbesondere der unteren Extremität. Radiologisch stellt er in den meisten Fällen eine scharf begrenzte, osteolytische Läsion dar. Histologisch zeigt er einen lobulären Aufbau mit einer chondroiden oder myxoiden Grundmatrix. Die Zellen sind spindelig bis sternförmig. Anhand von 40 Chondromyxoidfibromen soll die morphologische Variationsbreite dieser Tumorentität dargestellt werden. Die Fälle wurden nach Altersverteilung, Lokalisation und radiologischen sowie pathomorphologischen Kriterien untersucht. In 85% der untersuchten Fälle fanden sich die typischen histomorphologischen Kriterien des Chondromyxoidfibroms. Bei 5 Patienten (12,5%) kam es zu einem Rezidiv. 4 Fälle zeigten ein uncharakteristisches Bild und waren nur bedingt von anderen Knochentumoren (Chondroblastom, Chondrosarkom) abzugrenzen. Bei Beachtung strenger histomorphologischer Kriterien aber kann die Diagnose Chondromyxoidfibrom in den meisten Fällen sicher gestellt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050349
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  • 6
    Electronic Resource
    Electronic Resource
    Zur histologischen Gradeinteilung der Chondrosarkome Eine qualitative und quantitative Analyse an 74 Fällen des Hamburger Knochentumorregisters (1996)
    Springer
    Der Pathologe 17 (1996), S. 18-25 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Chondrosarkom ; Knochentumoren ; Grading ; Morphometrie ; Histologie ; Key words Morphometry ; Bone neoplasma ; Chondrosarcoma ; Grading ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Chondrosarcomas are frequent malignant bone tumors. Aside from different subtypes, such as dedifferentiated, mesenchymal and clear-cell chondrosarcoma, chondrosarcomas (classical chondrosarcoma) show different grades of differentiation. The borderline between chondroma and classical chondrosarcoma is not clearly defined. The same chondrosarcoma can be graded differently at different institutes. Standardized therapy concepts are currently in preparation. As the Hamburg Bone Tumor Registry is often consulted for chondrogenic tumors, the histological criteria are based on a series of 74 chondrosarcomas recorded there. The emphasis has been laid on a classification which can be used in daily routine and which is reproducible and in agreement with the classifications of other international groups. Grade I chondrosarcomas (50 %) can be distinguished only by growth criteria. The nuclei are small and show high chromatin density. Grade II chondrosarcomas (42 %) have medium-sized, regular nuclei with loose chromatin structure. The chondrocytes of grade III cases (8 %) show polymorphic nuclei. Binucleas forms, the number of mitoses and cellularity all show considerable overlap for all three grades. So far there are no immunohistological and molecular biological methods for reliable differentiation. The therapeutic consequences of the classification into grades are thorough curettage, in the case of grade I tumors, or complete resection, for grade II and III cases. The long-term results, however, need to be confirmed by a larger number of cases. From 1991 to 1995 the method was applied and proved to be easily practicable in daily diagnostic routine. Some 104 cases of classical chondrosarcomas (grade I 53 %, grade II 39 %, grade III 8 %) were analyzed. Two pathologists both assigned the same grade in 90 % of cases.
    Notes: Zusammenfassung Das Chondrosarkom gehört zu den häufigen malignen Knochentumoren. Neben unterschiedlichen Subtypen treten unterschiedliche Differenzierungsgrade des klassischen Chondrosarkoms auf. Die Übergänge von einem Chondrom, der benignen Variante chondrogener Tumoren, und dem klassischen Chondrosarkom sind histologisch fließend. Über die Bewertung der einzelnen Tumorformen liegen unterschiedliche Befunde vor. Einheitliche Therapiekonzepte werden derzeit erarbeitet. Deshalb werden die histologischen Kriterien an einer Serie von 74 Chondrosarkomen zusammengestellt. Dabei wird Wert auf eine in der täglichen Routine brauchbare und reproduzierbare Klassifikation gelegt. Grad-I-Chondrosarkome (50 %) können nur aufgrund von Wachstumskriterien von Chondromen unterschieden werden. Die Zellkerne sind klein, chromatindicht. Grad-II-Chondrosarkome (42 %) besitzen mittelgroße, gleichmäßige Zellkerne mit einem lockeren Chromatingerüst. Bei den Grad-III-Fällen (8 %) tritt eine Kernpolymorphie der Tumorchondrozyten auf. Sog. Doppelkernformen, die Zahl an Mitosen sowie die Zelldichte sind Kriterien mit einer großen Überschneidung in den 3 Differenzierungsgraden. Die therapeutischen Konsequenzen aus der Gradeinteilung sind entweder eine sorgfältige Kürettage bei Grad-I-Tumoren oder eine weite Resektion bei Grad-II- und Grad-III-Fällen. Die Langzeitergebnisse bedürfen allerdings noch einer Bewertung an größeren Kollektiven. Das Verfahren hat sich in der täglichen diagnostischen Praxis bei 104 Fällen mit einem klassischen Chondrosarkom als sehr gut anwendbar und reproduzierbar erwiesen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050130
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  • 7
    Electronic Resource
    Electronic Resource
    Solitäre Knochenzysten Morphologische Variationsbreite, Lokalisation, Häufigkeit und Differentialdiagnose (1996)
    Springer
    Der Pathologe 17 (1996), S. 63-67 
    Details
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Knochentumoren ; Solitäre Knochenzyste ; Histologie ; Key words Bone neoplasms ; Solitary bone cyst ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Analysis of 402 solitary bone cysts demonstrates the wide morphological variation of this cystic lesion with regard to histology and radiology. Aside from metaphyseal location in femur (33 %) and humerus (23 %), solitary bone cysts are also often located in calcaneus (11 %), tibia (11 %) and pelvis (10 %). Most patients are in the second decade of life. Differentiation between this benign lesion and malignant bone tumors is very important in daily clinical routine. The diagnosis cannot be based solely on radiological findings because of the variation of solitary bone cysts and the special forms, such as calcifying solitary bone cyst. Therefore, exact histological diagnosis is of particular importance.
    Notes: Zusammenfassung Anhand von 402 solitären Knochenzysten wird die große morphologische Variationsbreite dieser zystischen Läsionen in Histologie und Radiologie dargestellt. Neben der metaphysären Lage in Femur (33 %) und Humerus (23 %), stellen Kalkaneus (11 %), Tibia (11 %) und Becken (10 %) weitere häufige Lokalisationen solitärer Knochenzysten dar. Betroffen sind überwiegend Jugendliche in der 2. Lebensdekade. Die Abgrenzung dieser benignen Läsion gegenüber malignen Knochentumoren ist im klinischen Alltag besonders wichtig. Durch die radiologische Polymorphie der solitären Knochenzyste und ihre Sonderformen, wie die kalzifizierende solitäre Knochenzyste, ist die korrekte Diagnose allein klinisch nicht eindeutig zu stellen. Der exakten histologischen Diagnostik kommt damit besondere Bedeutung zu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050136
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  • 8
    Electronic Resource
    Electronic Resource
    Photosynthesis under osmotic stress (1981)
    Springer
    Planta 153 (1981), S. 423-429 
    Details
    ISSN: 1432-2048
    Keywords: Chloroplast envelope (permeability) ; Chloroplast stroma enzymes ; Spinacia ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Increasing the sorbitol concentration in a suspension of intact chloroplasts induced a fast, transient and not very specific efflux of metabolites from chloroplasts to the medium. Stroma proteins were retained by the chloroplasts. 2. Within the first 30 s following hypertonic stress, the chloroplast volume decreased according to the Boyle-Mariotte relation. A subsequent and transient increase suggested some influx of external solute. 3. Dark reactions of intact chloroplasts such as starch degradation and formation of labelled 3-phosphoglycerate from dihydroxyacetone phosphate or ribose-5-phosphate and 14CO2 were inhibited at low water potentials. After chloroplast rupture, the activity of stromal enzymes was decreased by high solute concentrations. Ribulose bisphosphate carboxylase exhibited a decrease of Vmax, while KmCO 2 remained unaltered. With sorbitol, sucrose, glycerol or glycinebetaine, 50% inhibition of enzymes was observed at osmotic potentials between 40 and 50 bar, with ethyleneglycol at about 70 bar. With salts such as KCl, 50% inhibition was found at 15 to 20 bar. 4. A comparison between inhibition of photosynthesis in intact chloroplasts and inhibition of enzymes in stroma extracts by solutes supports the notion that inhibition of photosynthesis at high osmotic potentials is mainly a solute effect. Another factor contributing to inhibition of photosynthesis in isolated chloroplasts is the loss of intermediates and cofactors which occurs during rapid osmotic dehydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394980
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  • 9
    Electronic Resource
    Electronic Resource
    Correlation between changes in photosynthetic activity and changes in total protoplast volume in leaf tissue from hygro-, meso- and xerophytes under osmotic stress (1982)
    Springer
    Planta 154 (1982), S. 538-545 
    Details
    ISSN: 1432-2048
    Keywords: Leaf slices ; Photosynthesis ; Protoplast volume ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rates of photosynthesis of leaf slices from various hygro-, meso- and xerophytes were measured in the absence of stomatal control in various stages of osmotic dehydration. The external osmotic potential π° for a 50% inhibition of photosynthesis varied between 20 bar in some hygrophytes up to 50 bar in xerophytes. The response of photosynthetic enzymes to increased salt concentrations in the reaction medium was similar in leaf extracts from hygro-, meso- and xerophytes. The total protoplast volume in vacuum-infiltrated leaf discs from various plants was measured as the difference between 3H2O-labeled space and [14C]sorbitol-labeled space. In all plants, the protoplast volume could be reduced to about 55% of the maximum volume of tissue in equilibrium with water, without decreasing photosynthesis. Reduction of the maximal protoplast volume below 55% decreased photosynthesis in all tissues to the same decreased photosynthesis in all tissues to the same degree. At 20% maximal volume, photosynthesis of all plants was completely inhibited. The differential decrease of protoplast volumes of various leaf tissues in response to changes in π° was mainly due to the different osmotic potential of the cell sap (πcs). The relative contribution of sugars to the overall osmolarity of the cell sap was up to nineteen times higher in xerophytes than in hygrophytes. Short-term recovery of photosynthesis after hypertonic stress was good in xerophytes, incomplete in mesophytes and absent in hygrophytes. There was also a large discrepancy between the partial recovery of protoplast volumes and the complete absence of a recovery of photosynthesis in hygrophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402997
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