Allometric analysis of the morphometric pulmonary diffusing capacity in dogs

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.     

Endurance training in humans: aerobic capacity and structure of skeletal muscle

The adaptation of muscle structure, power output, and mass-specific rate of maximal O2 consumption (VO2max/Mb) with endurance training on bicycle ergometers was studied for five male and five female subjects. Biopsies of vastus lateralis muscle and VO2max determinations were made at the start and end of 6 wk of training. The power output maintained on the ergometer daily for 30 min was adjusted to achieve a heart rate exceeding 85% of the maximum for two-thirds of the training session. It is proposed that the observed preferential proliferation of subsarcolemmal vs. interfibrillar mitochondria and the increase in intracellular lipid deposits are two possible mechanisms by which muscle cells adapt to an increased use of fat as a fuel. The relative increase of VO2max/Mb (14%) with training was found to be smaller by more than twofold than the relative increase in maximal maintained power (33%) and the relative change in the volume density of total mitochondria (+40%). However, the calculated VO2 required at an efficiency of 0.25 to produce the observed mass-specific increase in maximal maintained power matched the actual increase in VO2max/Mb (8.0 and 6.5 ml O2 X min-1 X kg-1, respectively). These results indicate that despite disparate relative changes the absolute change in aerobic capacity at the local level (maintained power) can account for the increase in aerobic capacity observed at the general level (VO2max).     

CORRELATED MORPHOMETRIC AND BIOCHEMICAL STUDIES ON THE LIVER CELL : II. Effects of Phenobarbital on Rat Hepatocytes

The changes occurring in rat hepatocytes during a 5 day period of treatment with phenobarbital were determined by morphometric and biochemical methods, particular attention being paid to the endoplasmic reticulum. The hepatocytic cytoplasm played an overwhelming part in the liver hypertrophy, while the hepatocytic nuclei contributed to only a moderate extent. The endoplasmic reticulum accounted for more than half of the increase in cytoplasmic volume. The increase in the volume and number of hepatocytic nuclei in the course of phenobarbital treatment was associated with changes in the ploidy pattern. Until the 2nd day of treatment both the rough-surfaced endoplasmic reticulum (RER) and the smooth-surfaced endoplasmic reticulum (SER) participated in the increase in volume and surface of the whole endoplasmic reticulum (ER). Subsequently, the values for RER fell again to control levels, whereas those for SER continued to increase, with the result that by the 5th day of treatment the SER constituted the dominant cytoplasmic element. The specific volume of mitochondria and microbodies (peroxisomes) remained constant throughout the duration of the experiment, while that of the dense bodies increased. The specific number of mitochondria and microbodies displayed a significant increase, associated with a decrease in their mean volume. The phenobarbital-induced increase in the phospholipid and cytochrome P-450 content of the microsomes, as well as in the activities of microsomal reduced nicotinamide-adenine dinucleotide phosphate-cytochrome c reductase and N-demethylase, was correlated with the morphometric data on the endoplasmic reticulum.     

Elektronenmikroskopische Untersuchungen an spezifischen Organellen von Endothelzellen des Frosches (Rana temporaria)

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 2 lang und 0,1 bis 0,5 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.

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Electron microscopic studies on specific organelles of endothelial cells in the frog (Rana temporaria)

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 2 in length and 0.1 to 0.5 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.

Herrn Prof. Dr. med. F. Hammersen und Fräulein Dr. med. M. Lewerenz danke ich herzlich für Anregungen, Unterstützung und Kritik. Die Arbeit entstand während eines vom Deutschen Akademischen Austauschdienst dankenswerterweise gewährten Stipendiums; sie wurde unterstützt vom Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung, Kredit-Nr. 3952.     

Membranes of Saccharomyces cerevisiae

A crude small particle pellet, obtained from postmitochondrial supernatant fractions of Saccharomyces cerevisiae, contains about half the ergosterol and phospholipid of crude cell homogenates. Most of the phospholipid of this pellet is in a “heavy” fraction which, with the aid of electron microscopy, shows membranous elements in addition to discrete particles. The “heavy” fraction, upon treatment with deoxycholate, can be freed of membranes, or, with ribonuclease treatment, ribosomes can be removed, leaving relatively clean membranes. The “heavy” fraction resembles the microsomes of animal cells, but contains considerably less lipids, including phospholipids, thus suggesting a less well-developed intracellular membrane system.     

Transpiration measurements on apple trees with an improved stem heat balance method

Since the late eighties a handy and user-friendly sap flow meter (Dynagage®) is on the market which can quantify 0205 the sap flow through intact plant stems, based on the stem heat balance method. The documentation about its accuracy and reliability, however, is still too limited to use it as a standard method in field experiments with apple trees. We therefore tested this commercial system on potted apple trees (Malus domestica L.; cv. Red Elstar and Jonagold; on rootstock M9 vf) with stem diameters of 1.8 to 4 cm. The measured sap flow was compared with mass loss measured by an automated balance, supposing the total mass loss of the trees was equal to the water loss by transpiration. The results revealed three major problems:

Biological safety considerations in the production of health care products from recombinant organisms

Safety considerations in the field of recombinant technology and rDNA production of health care products have been under discussion since the beginning of this technology in 1973 and will certainly go on. However no adverse effects, which could have been attributed to rDNA technology have been observed. On the other hand many life-saving and life-improving drugs have been on the market for many years to the benefit of many patients. New technologies and products thereof often provoke uncertainties about their impact on the environment or society. This article discusses some potential risks in the application of rDNA technology to drugs as well as some benefits for patients, society and environment.     

Biosafety investigations in an r-DNA production plant

Employees of a biotechnological production plant for recombinant interferon-2a have been participating in a 1-year study on occupational hygiene and the resulting biosafety aspects. Most of the employees have been employed in the plant for more than 6 years. Weekly stool samples were analysed for tetracycline (used as selection marker)-resistant coliforms as well as for rDNA (IFN gene) (interferon gene) and for the production organism. Various analytical methods, including the polymerase chain reaction, were applied to show that neither rDNA nor the production organism could be found in any of the stool samples and that there was no change or trend in the gut flora with respect to tetracycline resistance. In addition it could be shown that the tetracycline-resistance gene, as well as the rDNA, are completely inactivated in the course of the production process and thus no further recombination can take place. Blood samples were taken to show that none of the employees had anti-product antibodies. Correspondence to: E. K. Weibel     

Integrated stereological and biochemical studies of hepatocytic membranes. I. Membrane recoveries in subcellular fractions

Previous attempts to relate the structure and function of hepatocytic membranes have compared biochemical data of fractions to morphological data derived from either intact tissue or fractions. The effects of the original homogenization aside, biochemical recoveries comparing membrane marker enzymes of the homogenate to subsequent fractions suggest a general conservation of activity. A sterological study was undertaken to estimate membrane surface areas in the intact tissue, homogenate, and fractions of the same livers and then to test the comparability of these data with membrane marker enzymes by calculating both morphological and biochemical recoveries. The sterological data were corrected for errors due to section thickness and compression. The average total membrane sufrace area per 1 g of liver was 9.3 m2 in the intact tissue (T), 7.8 m2 in the homogenate (H), and 7.4 m2 in the fractions (F); recoveries for the membrane surface areas thus averaged 96% for the (F/H) and 81% for the (F/T) comparisons. In homogenate and fractions, the differentiability of membranes by morphological criteria was limited to rough- and smooth- surfaced membranes, as well as outer and inner mitochondrial membranes. The recoveries of rough-surfaced membranes were 101% for F/H and 92% for F/T; those of smooth-surface membranes were 89% for F/H and 107% for F/T. For mitochondrial membranes, a recovery of 100% for F/H was obtained, whereas it amounted to only 54% for F/T. With respect to F/H, the membrane recoveries compare well with the marker enzyme recoveries obtained biochemically. The extension of recovery calculations to the intact tissue (F/T) revealed satisfactory conservation of the procedures of homogenization and fractionation; it indicates, however, that a shift of a substantial part of mitochondrial membranes to the pool of unidentifiable smooth membranes may occur on homogenization.