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  • 1
    Electronic Resource
    Electronic Resource
    Physiology The pitfalls of power laws (2002)
    [s.l.] : Nature Publishing Group
    Nature 417 (2002), S. 131-132 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Why does a mouse burn six times more energy per unit body mass per minute than a human? The intuitive answer is to keep warm. In 1883, Rubner found that the metabolic rate depended on the body's surface-to-volume ratio, or M2/3, where M is the body mass, thus supporting the notion of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/417131a
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  • 2
    Electronic Resource
    Electronic Resource
    Absence of acid phosphatase activity in specific endothelial organelles (1969)
    Springer
    Histochemistry and cell biology 20 (1969), S. 143-149 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Endothelial specific organelles in the aorta and in the small pulmonary blood vessels were investigated by electron microscopy with respect to their acid phosphatase activity. As controls, acid phosphatase reactions performed on liver and lung tissue showed, as expected, positive results. Since the endothelial specific organelles were in each case free of reaction product, it was concluded that they do not have a lysosomal function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00268708
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  • 3
    Electronic Resource
    Electronic Resource
    The ultrastructure of the normal human skeletal muscle (1973)
    Springer
    Pflügers Archiv 344 (1973), S. 217-232 
    Details
    ISSN: 1432-2013
    Keywords: Morphometry ; Skeletal Muscle ; Aerobic Power ; Training ; Sex Differences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle biopsies were taken from the middle part of the vastus lateralis muscle of 9 men, who were not regularly involved in endurance training (M, average $$\dot V_{{\text{O}}_{\text{2}} } $$ max=61.3 ml/min·kg), 3 sedentary women (W, $$\dot V_{{\text{O}}_{\text{2}} } $$ max=43.7 ml/min·kg) and 5 well trained orienteers (TO, $$\dot V_{{\text{O}}_{\text{2}} } $$ max=76.1 ml/min·kg). Morphometric analysis of 60 electron micrographs per biopsy gave the following significant differneces: 1. The volume density of central mitochondria was 1.47-fold higher in TO than in M, and 1.44-fold higher in M than in W. 2. The volume density of peripheric mitochondria was 3.22 times higher in TO compared to M. 3. The ratio of the central mitochondrial volume to the volume of myofibrils was 1.54-fold higher in TO compared to M, while the respective ratio was 1.49 for M compared to W. 4. The surface of the central mitochondria was 1.28-fold higher in TO than in M and 1.35-fold higher in M than in M. 5. The surface of mitochondrial cristae was higher by a factor of 1.62 in TO compared to M and 1.35 in M compared to W. 6. The central mitochondria were larger in TO compared to M by a factor of 1.12. 7. The volume density of intracellular lipid (triglyceride droplets), was 2.5-fold higher in TO than in M. There were highly significant correlations between $$\dot V_{{\text{O}}_{\text{2}} } $$ max and volume density of central mitochondria (r=0.82), surface of mitochondrial cristae (r=0.80) and the ratio of mitochondrial volume to myofibrillar volume (r=0.78). No quantitative changes could be observed in mitochondrial fine structure. Neither volume density of sarcoplasma nor volume and surface density of the tubular system showed any difference as a function of training and sex. It is postulated that a) an individual's maximum oxygen intake is limited not only by the capacity of the oxygen transport system but also by the oxidative capacity of mitochondria in the skeletal muscles, and b) the skeletal muscle of trained athletes contains a much higher quantity of intracellular lipids (triglyceride droplets) as a substrate directly available for energy production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588462
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of cold environment on skeletal muscle mitochondria in growing rats (1982)
    Springer
    Cell & tissue research 225 (1982), S. 427-436 
    Details
    ISSN: 1432-0878
    Keywords: Rat ; Cold adaptation ; Skeletal muscle ; Mitochondria ; Fat ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Growing rats (4 weeks old) were kept for 3 weeks at 11° C and 24° C respectively. The cold-adapted animals showed a significantly higher oxygen consumption (64%). Volume density of subsarcolemmal and interfibrillar mitochondria as well as volume density of fat droplets were estimated in M. soleus and the diaphragm of both groups. In cold-adapted animals, the total volume of mitochondria was significantly increased by 24% in diaphragm and 37% in M. soleus. The volume of subsarcolemmal mitochondria was almost doubled in each muscle, but the volume of interfibrillar mitochondria did not change significantly. The surface of the inner mitochondrial membranes per unit volume of mitochondrion in M. soleus was significantly increased both in interfibrillar and subsarcolemmal mitochondria, whereas the surface of the outer mitochondrial membranes per unit volume of mitochondrion was increased only in the subsarcolemmal mitochondria. The volume of fat droplets in the diaphragm and M. soleus of cold adapted animals increased significantly by 62% and 150% respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214693
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of long-term hypergravity on muscle, heart and lung structure of mice (1997)
    Springer
    Journal of comparative physiology 167 (1997), S. 494-501 
    Details
    ISSN: 1432-136X
    Keywords: Key words Morphometry ; Mitochondria ; Myofibrils ; Capillaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Quantitative changes in lung, heart and muscle structure were assessed in mice exposed for 14 weeks to a gravitational field of 3 G since the age of 4 weeks; matched controls were kept at normal gravity (1 G). The body mass of 3-G-exposed mice was significantly reduced by 9%, while total skeletal muscle mass remained the same fraction of body mass. The mass of the soleus muscle was found to be significantly larger in 3-G-exposed mice both in absolute (+27%) and body mass specific terms (+42%). Capillary density was significantly reduced by 22% because of a relatively larger increase of fiber cross-sectional area (+47%) than of capillary to fiber ratio (+16%). Other morphometric variables remained unchanged with hypergravity. Heart mass and mitochondrial volume were both larger in 3-G-exposed mice (+15% and +27%, respectively). This difference reached statistical significance when normalized to body mass. The only significant difference in lung structure detectable by morphometric methods were a smaller volume (−9%), that paralleled lower body mass, and thinner alveolar septa (−12%). From these results it is concluded that the lung's support structures in mice are sufficiently strong to withstand the stress of long-term hypergravity; however, 3-G exposure leads to a selective hypertrophy of soleus muscle fibers while absolute capillary length in this muscle remains unaltered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050101
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  • 6
    Electronic Resource
    Electronic Resource
    Morphometrische Untersuchung der Verteilung einer spezifischen cytoplasmatischen Organelle in Endothelzellen der Ratte (1966)
    Springer
    Cell & tissue research 73 (1966), S. 1-9 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Verteilung einer spezifischen stäbchenförmigen Organelle von Endothelzellen im Blutgefäßsystem der Ratte wird elektronenmikroskopisch mit morphometrischen Methoden untersucht. Es findet sich eine eindeutige Abhängigkeit des Volumenanteils der Organelle am Cytoplasma der Endothelzelle von der Gefäßgröße. Gefäße des kleinen Kreislaufs enthalten signifikant mehr dieser Organellen als entsprechende Gefäße des großen Kreislaufs. Mögliche funktionelle Bedeutungen dieser Organellen werden diskutiert.
    Notes: Summary The distribution of a specific rod-shaped organelle of endothelial cells in the vascular system of the rat is investigated with methods of morphometric electron microscopy. The volumetric fraction of endothelial cytoplasm occupied by these organelles depends on vessel size. Vessels of pulmonary circulation contain significantly more of these organelles than comparable systemic vessels. Possible functional implications of these organelles are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348463
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  • 7
    Electronic Resource
    Electronic Resource
    Beeinflussung einer spezifischen cytoplasmatischen Organelle von Endothelzellen durch Adrenalin (1968)
    Springer
    Cell & tissue research 88 (1968), S. 426-440 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Blutgefäßendothelien der Wirbeltiere enthalten eine spezifische cytoplasmatische Organelle, der nach einer schon früher geäußerten Hypothese eine Funktion im Rahmen der Blutgerinnung zukommen könnte. Da Adrenalin fähig sein soll, aus der Aortenwand eine gerinnungsaktive Substanz freizusetzen, wurde in vitro an 5 Rattenaorten die Wirkung einer „physiologischen“ Adrenalinlösung auf die endothelspezifische Organelle geprüft. Als Kontrolle dienten direkt fixierte, sowie in Ringerlösung inkubierte Aortenringe des gleichen Tieres. Die durch die Inkubation hervorgerufenen morphologischen Veränderungen der Gefäßintima werden beschrieben und besprochen. Mit stereologischen Methoden wurde die Volumendichte der Endothelkörperchen in den Kontroll- und Testgruppen ermittelt und miteinander verglichen. Adrenalin vermag binnen 20 sec die Volumendichte der Organellen in Endothelcytoplasma auf ca. 60% des Kontrollwertes zu verringern. Diese Abnahme ist statistisch signifikant (P 〈 0,001). Die oft beobachteten engen topographischen Beziehungen der Organellen mit der Zellmembran lassen an eine Stoffabgabe ins Gefäßlumen denken. Die Resultate stützen die Hypothese, daß diese Organellen eine von verschiedenen Seiten postulierte, gerinnungsaktive Substanz enthalten könnten.
    Notes: Summary Endothelial cells of vertebrate blood vessels contain specific cytoplasmic organelles, distinguishable from other dense bodies by their rod shape and internal tubular substructure. The following observations led to the hypothesis that these organelles could correspond to a procoagulative substance previously observed in arterial walls. a) These organelles have some resemblance to α-granules of thrombocytes which proved to be procoagulative elements. b) Intima and endothelium of human aorta contain thromboplastic substances. c) Large blood vessels contain more organelles, a fact which could be explained as an indication of their blood-directed function. d) The epinephrine perfused rabbit aorta delivers a coagulation activating substance into the perfusate. To check this hypothesis strips of aortic wall of five rats were incubated in 0.5 μg-% epinephrine solution for 20 sec and as controls in Ringer solution. By comparison some material was directly fixed by immersion in 1% OsO4. The volume-density of organelles in endothelial cytoplasm was determined by means of stereologic methods. On the average the volume-density decreased from 0.93% in immediatly fixed, to 0.83% in Ringer incubated, and to 0.53% in epinephrine incubated tissue samples. The diminution after Ringer incubation can be explained by swelling of cytoplasm. The loss of some 40% of organelles between Ringer and epinephrine incubated material is statistically highly significant. Evidence is presented that the organelles are expulsed towards the vessel lumen. These results give support to the hypothesis that these organelles could contain a procoagulative substance of aortic endothelium postulated by several authors. Further experiments are needed to prove this relationship.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00540670
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  • 8
    Electronic Resource
    Electronic Resource
    A stereologic electron microscope study of “tubular myelin figures” in alveolar fluids of rat lungs (1966)
    Springer
    Cell & tissue research 69 (1966), S. 418-427 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The three-dimensional structure of a composite material found in alveolar exudate of oxygen poisoned lungs but also present in normal lungs is stereologically analysed. It is composed of tubules of 450 Å diameter which are tightly packed in a quadratic lattice. The wall of the tub vile is formed by “four-winged” osmiophilic filaments which are located in the corners of the quadratic lattice; their interior is made up of a hydrophilic substance which contains either a tubule or a filament of moderate electron density. The osmiophilic substance of the walls is continuous with associated myelin figures which can be resolved into lamellae with a periodicity of 42 Å and can thus be considered to be water crystals of phospholipids. The nature of the content of the tubules, which presumably exerts the formative force on the phospholipid lamellae to form tubules, remains undetermined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406293
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  • 9
    Electronic Resource
    Electronic Resource
    Allometric analysis of the morphometric pulmonary diffusing capacity in dogs (1981)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 168 (1981), S. 5-15 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The lung volume, the morphometrically determined alveolar and capillary surface area, and the capillary volume of 27 dogs (weight 2.65-57 kg) all were linearly correlated with body weight. The thickness of the air-blood barrier increased only slightly with increasing body size. The structural diffusing capacity, containing these parameters, was used to estimate the gas exchange capabilities of the lung and was also found to scale in direct proportion to body size. This coincides with reports on physiologically estimated diffusing capacity but is obviously different from the interspecies slope for metabolism which scales to the 3/4 power of body weight.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051680104
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  • 10
    Electronic Resource
    Electronic Resource
    Elektronenmikroskopische Untersuchungen an spezifischen Organellen von Endothelzellen des Frosches (Rana temporaria) (1970)
    Springer
    Cell & tissue research 108 (1970), S. 105-126 
    Details
    ISSN: 1432-0878
    Keywords: Endothelium ; Specific organelles ; Ultrastructure ; Rana temporaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Endothelzellen der Wirbeltiere enthalten spezifische Organellen, deren Funktion unbekannt ist. Diese Organellen werden beim Frosch (Rana temporaria) nach unterschiedlichen Fixierungen elektronenmikroskopisch untersucht. Die Organellen sind walzenförmig mit mannigfachen Abweichungen, bis zu 2μ lang und 0,1 bis 0,5μ dick. Ihre oft unterbrochene Außenmembran ist dicker als zytoplasmatische Membranen. Das Innere der Organellen besteht aus Tubuli, die in eine elektronendichte Matrix eingebettet sind. Die Dichte dieser Matrix zeigt deutliche Abstufungen. Die Tubuli sind möglicherweise aus einer spiralförmigen Molekülkette aufgebaut. Das Verteilungsmuster der Organellen wird mit stereologischen Methoden untersucht. Die größte Volumendichte weisen die Aortae thoracicae mit 8% auf. Die Volumendichte der Organellen im Zytoplasma der Endothelzellen scheint mehr von der Entfernung der betreffenden Gefäßstrecke zum Herzen abzuhängen als von der Gefäßgröße. Es werden Verbindungen der Organellen zu zytoplasmatischen Membransystemen aufgezeigt. Auf Besonderheiten des Endothels, darunter Aggregationen von Ribosomen, wird hingewiesen.
    Notes: Summary Endothelial cells of vertebrates contain specific organelles of unknown function. These organelles are studied by electron microscopy with different fixations. The organelles are rod-shaped with many variations, up to 2μ in length and 0.1 to 0.5 μ in thickness. Their outer membrane, which is often discontinuous, is thicker than cytoplasmic membranes. The density of the matrix shows distinct gradations. The organelles contain tubules, possibly built up by a spiral molecular chain. The distribution of the organelles is investigated with stereological methods. Their volume density in endothelial cell cytoplasm appears to depend more on the distance from the heart than on vessel size, the thoracic aortae showing the highest organellae content of 8%. Connections between organelles and cytoplasmic membranes are demonstrated. Particularities of endothelium, among them aggregations of ribosomes, are pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335946
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