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Joachim -Hermann Scharf 《Cell and tissue research》1967,80(1):124-139
Zusammenfassung Eine Analyse der Meßwerte von Ronge (1943) über die Reizausnutzung durch das Tastsinnes-Nervensystem der Haut zeigt im Zusammenhang mit einer vorausgegangenen Studie (Scharf und Blumenthal, 1967), daß der Reizerfolg in einer transzendenten Fläche höherer Ordnung in Abhängigkeit vom Lebensalter (oder von der Anzahl der Meissnerschen Tastkörperchen pro Hautflächeneinheit) und vom Reizdruck dargestellt werden kann. In Druckrichtung steigt diese Fläche mit zunehmendem Reizdruck nichtlinear an, in Zeitrichtung oscilliert die Fläche dagegen träge um Normwerte, die beim 20jährigen Menschen realisiert sind. Dabei werden die Altersveränderungen der histologischen Hautstruktur offenbar zur Kompensation der altersabhängigen Verminderungen der Zahl der Tastkörperchen ausgenutzt.
Mit dankenswerter Unterstützung durch einen Forschungsauftrag des Staatssekretariates für das Hochschulwesen der DDR.
Numerische Rechnung: Tischrechner Mercedes Cellatron R 44 SM, Leitende Med. techn. Ass. Ruth Pieper (Anatomisches Institut Halle). Programmgesteuerter Digitalrechner ZRA 1, Math, techn. Ass. Friedegund Hüther (Institut für Numerische Mathematik, Halle).
Graphik: Akad. Bildhauer Hellmut Helwin. 相似文献
Summary An analysis of the observations on the Reizausnutzung by nerves of touch (Ronge, 1943) connected to a previous study (Scharf and Blumenthal, 1967) shows that the irritation result may be figured by a transcendental plane of higher order as a function of age (or number of Meissner's corpuscles per area skin) and irritation pressure. Along the pressure axis this non-linear plane is increasing non-linear in dependence on ascending pressure, but along the time axis the plane oscillates lazily round about the norm values which are realized in human beings of about 20 years of age. It seems that the age-dependent changes of histological skin structure are utilized to compensate the age-dependent diminution of touch corpuscle number.
Mit dankenswerter Unterstützung durch einen Forschungsauftrag des Staatssekretariates für das Hochschulwesen der DDR.
Numerische Rechnung: Tischrechner Mercedes Cellatron R 44 SM, Leitende Med. techn. Ass. Ruth Pieper (Anatomisches Institut Halle). Programmgesteuerter Digitalrechner ZRA 1, Math, techn. Ass. Friedegund Hüther (Institut für Numerische Mathematik, Halle).
Graphik: Akad. Bildhauer Hellmut Helwin. 相似文献
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In previous studies, aluminium was found to retard bacterial growth and enhance porphyrin formation in Arthrobacter aurescens RS-2. The aim of this study was to establish the mechanism of action of aluminium which leads to increased porphyrin production. Cultures of Arthrobacter aurescens RS-2 were incubated in the absence and presence of 0.74 mm aluminium. After 6 and 24 h of incubation, various parameters of the haem biosynthetic pathway were determined. After 6 h of incubation with aluminium, the activities of the enzymes aminolevulinate synthase (ALAS), aminolevulinate dehydratase (ALAD), porphobilinogen deaminase (PBGD) and uroporphyrinogen decarboxylase (UROD) were increased by 120, 170, 190 and 203%, respectively, while that of ferrochelatase (FC) was found to be unchanged. However, after 24 h of incubation, no change in the activities of ALAS and ALAD was noted, while an about 2-fold increase in PBGD and UROD activities were observed. FC activity was decreased by 63%. It was concluded that aluminium exerts its effect by inducing the enzymes PBGD and UROD rather than by a direct or indirect effect on ALAS. Its effect on the final step in the haem biosynthetic pathway is discussed. 相似文献
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Rainer Scharf Malte Meesmann Jan Boese Dante R. Chialvo Klaus -D. Kniffki 《Biological cybernetics》1995,73(3):255-263
Counting statistics in the form of the variance-time curve provides an alternative to spectral analysis for point processes exhibiting 1/f β-fluctuations, such as the heart beat. However, this is true only for β<1. Here, the case of general β is considered. To that end, the mathematical relation between the variance-time curve and power spectral density in the presence of 1/f β-noise is worked out in detail. A modified version of the variance-time curve is presented, which allows us to deal also with the case β?1. Some applications to the analysis of heart rate variability are given. 相似文献
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Exaggerated inspiratory swings in intrathoracic pressure have been postulated to increase left ventricular (LV) afterload. These predictions are based on measurements of LV afterload by use of esophageal or lateral pleural pressure. Using direct measurements of pericardial pressure, we reexamined respiratory changes in LV afterload. In 11 anesthetized vagotomized dogs, we measured arterial pressure, LV end-systolic (ES) and end-diastolic transmural (TM) pressures, stroke volume (SV), diastolic left anterior descending blood flow (CBF-D), and coronary resistance. Dogs were studied before and while breathing against an inspiratory threshold load of -20 to -25 cmH2O compared with end expiration. Relative to end expiration, SV and LVES TM pressures decreased during inspiration and increased during early expiration, effects exaggerated during inspiratory loading. In all cases, LV afterload (LVES TM pressure) changed in parallel with SV. LV end-diastolic TM pressure did not change. CBF-D paralleled arterial pressure, and there were no changes in coronary resistance. In two dogs, regional LVES segment length paralleled calculated changes in LVES TM pressure. We conclude that 1) LV afterload decreases during early inspiration and increases during early expiration, changes secondary to those in SV; 2) changes in CBF-D are secondary to changes in perfusion pressure during the respiratory cycle; and 3) the use of esophageal or lateral pleural pressure to estimate LV surface pressure overestimates changes in LV TM pressures during respiration. 相似文献
7.
H Manning F D McCool S M Scharf E Garshick R Brown 《Journal of applied physiology》1992,73(3):825-831
We hypothesized that, in quadriplegia, chest wall distortion would increase the energy cost of ventilation. To assess this, we measured the oxygen cost of breathing (VO2 resp) and changes in chest wall configuration during inspiratory resistive-loaded breathing tasks in five quadriplegic and five normal subjects. Each subject performed three breathing tasks that spanned a range of work rates (Wtot). Configurational changes of the abdomen and upper, lower, and transverse rib cage were assessed with magnetometers. We found that 1) in both groups, VO2resp increased linearly with Wtot over the range of tasks performed, 2) the mean slope of the regression line of VO2resp vs. Wtot was greater for quadriplegic than for normal subjects (3.7 +/- 0.8 vs. 2.0 +/- 0.7 ml O2/J, P less than 0.01), 3) efficiency of breathing (Wtot/VO2resp) was less for quadriplegic than for normal subjects (1.9 +/- 0.6 vs. 3.5 +/- 1.4%, P less than 0.001), 4) during inhalation, upper and lower rib cages behaved similarly in the two groups, but the quadriplegic subjects had a decrease in transverse rib cage and a much greater increase in abdomen than normal subjects, and 5) functional residual capacity decreased in normal but not in quadriplegic subjects during the breathing tasks. We conclude that the lesser efficiency of breathing in quadriplegia may be related to the elastic work of chest wall distortion, shorter mean operational diaphragm length, and possibly differences between normal and quadriplegic subjects in mechanical advantage of available inspiratory muscles. 相似文献
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Isolated perfused dog hearts were made hypoxic by respiring the support dog with low oxygen (hypoxic hypoxia) or with carbon monoxide (CO hypoxia). Each heart was exposed to both types of hypoxia, separately. Effects on coronary flow (Qt), coronary vascular resistance, cardiac oxygen consumption (Vo2), and contractility (%deltadP/dt) were studied. Two series of experiments were done. Series I: At constant perfusion pressure. As oxygen content (Cao2) was lowered from 20 to 5 vol%, Qt doubled with hypoxic hypoxia and almost tripled with CO hypoxia (P less than 0.01). Vo2 and contractility increased with both types of hypoxia. Beta-adrenergic blockade eliminated the increase in VO2 and contractility but not the difference in Qt increase between hypoxic and CO hypoxia. Series II: At constant Qt (with beta-blockade), vascular resistance decreased more with CO than hypoxic hypoxia. Finally, alpha-blockade eliminated the difference in vascular resistance and thus with complete (alpha and beta) blockade, the two types of hypoxia have the same effect and are indistinguishable. 相似文献
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The bacterial paromomycin resistance gene, aphH, as a dominant selectable marker in Volvox carteri 总被引:1,自引:0,他引:1
The aminoglycoside antibiotic paromomycin that is highly toxic to the green alga Volvox carteri is efficiently inactivated by aminoglycoside 3′-phosphotransferase from Streptomyces rimosus. Therefore, we made constructs in which the bacterial aphH gene encoding this enzyme was combined with Volvox cis-regulatory elements in an attempt to develop a new dominant selectable marker – paromomycin resistance (PmR) – for use in Volvox nuclear transformation. The construct that provided the most efficient transformation was one in which aphH was placed between a chimeric promoter that was generated by fusing the Volvox hsp70 and rbcS3 promoters and the 3′ UTR of the Volvox rbcS3 gene. When this plasmid was used in combination with a high-impact biolistic device, the frequency of stable PmR transformants ranged about 15 per 106 target cells. Due to rapid and sharp selection, PmR transformants were readily isolated after six days, which is half the time required for previously used markers. Co-transformation of an unselected marker ranged about 30%. The chimeric aphH gene was stably integrated into the Volvox genome, frequently as tandem multiple copies, and was expressed at a level that made selection of PmR transformants simple and unambiguous. This makes the engineered bacterial aphH gene an efficient dominant selection marker for the transformation and co-transformation of a broad range of V. carteri strains without the recurring need for using auxotrophic recipient strains. 相似文献