Showing papers by "University of Amsterdam published in 1970"
TL;DR: In this paper, the combinatorial properties of rigid plane skeletal structures are investigated, and the properties are found to be adequately described by a class of graph-structured graphs.
Abstract: In this paper the combinatorial properties of rigid plane skeletal structures are investigated. Those properties are found to be adequately described by a class of graphs.
1,117 citations
TL;DR: As many diagnostic methods that belong to the impressive advance in obstetrics of recent Years are not completely harmless, it is very important for us to know under which conditions these methods should be applied.
658 citations
TL;DR: In this paper, morphologic and morphometric studies were carried out on pulmonary vessels in lung tissue from 156 patients, for whom a diagnosis of primary pulmonary hypertension had been made, for which the media is only slightly thicker than normal; in 31 of the 156 cases the vascular lesions corresponded to this pattern.
Abstract: Morphologic and morphometric studies were carried out on pulmonary vessels in lung tissue from 156 patients, for whom a diagnosis of primary pulmonary hypertension had been made. This material was collected from 51 medical centers. Chronic pulmonary thromboembolism can be recognized by organizing thrombi, patchy intimal fibrosis, and intra-arterial septa. The media is only slightly thicker than normal; in 31 of the 156 cases the vascular lesions corresponded to this pattern. Other conditions such as chronic pulmonary venous hypertension, pulmonary veno-occlusive disease, sarcoidosis, chronic bronchitis, and pulmonary schistosomiasis could also be classified from the morphologic criteria. The largest group comprised 110 cases showing medial hypertrophy, laminar intimal fibrosis, and often fibrinoid necrosis, arteritis, and plexiform lesions. These alterations suggest that they were initiated by vasoconstriction. In children the sex ratio is equal; in adults there are almost four females to one male. In the...
500 citations
TL;DR: Seven types have been distinguished within the class of Gomori-positive cells on the basis of different staining reactions with the alcian blue/alcian yellow technique, which revealed that each of the histochemically distinguished secretory substances consists of elementary granules which differ in size and appearance from each other and from the neurosecretory elementarygranules which have been described in the cerebral ganglia and in the lateral lobes.
Abstract: In the central ganglia of Lymnaea stagnalis neurosecretory cell groups have previously been identified by means of chrome-haematoxylin or paraldehyde-fuchsin stains. In the present study seven types have been distinguished within the class of Gomori-positive cells on the basis of different staining reactions with the alcian blue/alcian yellow technique. Five types are located in the cerebral ganglia and in the lateral lobes, whereas two cell types occur in the ganglia of the visceral ring. No neurosecretory cells have been observed in the buccal and pedal ganglia. The staining technique used proved to be superior to the classic neurosecretory stains, because with this method the secretory substances can easily be distinguished from nonsecretory Gomori-positive tissue constituents. One of the two Gomori-negative neurosecretory cell types of the cerebral ganglia react positively with the alcian blue/alcian yellow technique. In addition, two Gomori-negative neurosecretory cell types, which had not been described before, were identified in the visceral ring. The ultrastructure of the four neurosecretory cell types in the visceral ring is described. The electron microscope revealed that each of the histochemically distinguished secretory substances consists of elementary granules which differ in size and appearance from each other and from the neurosecretory elementary granules which have been described by other authors in the cerebral ganglia and in the lateral lobes. The neurohaemal areas of the neurosecretory cells in the visceral ring are very extensive and include the peripheral parts of the nuchal nerves and of the connectives and nerves of the ganglia of the ring. The perineurium and the adjacent parts of the connective tissue which surround the ganglia, the connectives and the nerves are regarded as additional neurohaemal zones, because in these regions many tiny nerves occur, which consist mainly of neurosecretory axons ending non-synaptically near parts of the vascular system. In the perineurium surrounding the cerebral ganglia and their neurohaemal area a similar network of neurosecretory fibres was observed. Indications of release of the secretory material were regularly observed. Release apparently takes place by exocytosis. A circadian rhythmicity was observed in the release activity of some of the neurosecretory cell types.
226 citations
TL;DR: It is concluded that the intact mitochondrial DNA of S. carlsbergensis and S. cerevisiae consists of a circular molecule with a contour length of approx.
200 citations
TL;DR: Based on the assumption that the bc1 segment of the respiratory chain contains 2b:1c1:1 antimycin-binding sites, the specific quenching of antimYcin fluorescence by binding to cytochrome b enables an accurate determination of the absorbance coefficients of cytochromes b and c1.
179 citations
TL;DR: In the eight Pardosa species studied, aerial dispersal occurs generally in the young instars, with species with relatively high and relatively low dispersal capacities within the different systematic groups in the genus.
Abstract: In the eight Pardosa species studied, aerial dispersal occurs generally in the young instars. The climatic conditions, particularly wind but also temperature and humidity, affect the occurrence of aerial dispersal. Within the different systematic groups in the genus, species with relatively high and relatively low dispersal capacities occur. These differences in dispersal capacity are discussed in relation with the abundance and stability of the habitat, in which the species are found.
147 citations
146 citations
TL;DR: In this paper, serial autocorrelation functions and histograms of R-R intervals in patients with atrial fibrillation, with and without digitalis, at rest and during exercise, were produced by a computer.
Abstract: Serial autocorrelation functions and histograms of R-R intervals in patients with atrial fibrillation, with and without digitalis, at rest and during exercise, were produced by a computer. At rest with and without digitalis the first and higher order coefficients did not differ from zero. During exercise (also with and without digitalis) only the first autocorrelation coefficient became slightly positive (in the order of 0.07) whereas the form of the histograms was profoundly altered by both exercise and digitalis. The change in form of the histograms reveals the change in electrophysiologic properties of the A-V conduction system. Since the serial autocorrelation functions were not influenced by digitalis and only slightly by exercise, the conclusion seems justified that the refractory period of, and the concealed conduction in, the A-V system cannot be (solely) responsible for the random nature of the ventricular rhythm in patients with atrial fibrillation. The effect of randomly spaced atrial impulses of random strength reaching the A-V node from random directions can explain these results.
139 citations
TL;DR: There is a difference in sensitivity of the phosphate-hydroxyl and phosphatedicarboxylate exchange reactions, depending on the sulphydryl-blocking reagent used.
134 citations
TL;DR: This communication reports the finding of an EP correlate of binocular depth perception in man.
Abstract: IT is known that within the visual pathway of the brains of anaesthetized animals single units can be found which respond optimally when both eyes are simultaneously stimulated with light1–3. The characteristics of such binocular units are consistent with psychophysically observed features of binocular depth perception4–6. At present, human subjects have important advantages over animals in studies of stereopsis because with human subjects the critical binocular fusion and subjective reports of depth perception can easily be obtained. With human subjects, however, any electrophysiological information must be obtained by the analysis of scalp evoked potentials (EPs). This communication reports the finding of an EP correlate of binocular depth perception in man.
TL;DR: An approach which has been applied succesfully in the analysis of certain nonlinear biological systems is presented, capable to recognize in these systems the linear and nonlinear elements.
Abstract: Physical and especially biological systems behave many times in such a way that the methods of linear system analysis are not adequate, even when “small” signals are used.
TL;DR: The proposed mechanisms by which uncoup ling compounds dissipate energy in mitochondria and chloroplasts are essentially based on observations that uncouplers interact with these organelles at the level of the osmotically active membranes.
TL;DR: Investigation on the effect of pH on anionic substrate translocation across the mitochondrial membrane shows that their distribution across the inner membrane can be governed by transmembrane pH difference, but evidence is presented that the translocation of Pi, but not that of malate, α-oxoglutarate, or citrate can bedirectly coupled to an OH− counterflux.
Abstract: The translocation of Pi, malate, α-oxoglutarate, and citrate across the inner membrane of rat-liver mitochondria has been studied. Investigation on the effect of pH on anionic substrate translocation across the mitochondrial membrane shows that their distribution across the inner membrane can be governed by transmembrane pH difference. However, evidence is presented that the translocation of Pi, but not that of malate, α-oxoglutarate, or citrate can bedirectly coupled to an OH− counterflux (H2PO
4
−
−OH− exchange-diffusion). and malate-tricarboxylate exchange-diffusion reactions is directly demonstrated. The study of the effect of uncouplers on the efflux from mitochondria of substrate anions, in the absence of counteranion, and on the anion exchange-diffusions shows that uncouplers act in at least two ways: they promote the efflux of Pi from mitochondria and inhibitdirectly the exchange-diffusion reactions. The kinetics of this inhibition are described. These results are discussed in the light of previous work on the effect of uncouplers on the distribution of substrate anions across the inner membrane of isolated mitochondria. Coupling mechanisms in substrate anion translocation and aspects of the energetics of anion translocation are discussed.
TL;DR: A method of volumetric measurement of breast tissue before and during reduction mammaplasty is described and its application to breast reduction surgery is described.
TL;DR: It is proposed that antimycin, a multi-site inhibitor in particles, reacts preferentially with and stabilizes a high-energy form of cytochrome bi (bi∼X) (refs. 4 and 5).
Abstract: SUB-MITOCHONDRIAL particles prepared from horse or ox heart contain two species of cytochrome b in equal amounts, one (bi) affected by antimycin and the other (b) not affected1–3. In addition to its well known inhibitory effect on the respiratory chain, acting between cytochromes b and c1, antimycin brings about an increased reduction of the total cytochrome b present in sub-mitochondrial particles and causes a shift in absorption of 1–2 nm towards longer wavelengths of the b band. This “redshift” is best studied with the wavelength pair 566–560 nm, for the absorption maximum of ferrocytochrome b is at 563 nm, and A566–560 nm is not affected by the redox state of cytochrome b (ref. 1). Sigmoidal curves for the antimycin effect are found with sub-mitochondrial particles4 and with intact white potato (W. D. Bonner and E. C. S., unpublished) or rat heart (H. J. W., J. A. B. and E. C. S., unpublished) mitochondria in the presence of uncoupler, and linear (or hyperbolic) with energized mitochondria (state 4). To explain these antimycin effect curves, it is proposed that antimycin, a multi-site inhibitor in particles, reacts preferentially with and stabilizes a high-energy form of cytochrome bi (bi∼X) (refs. 4 and 5).
TL;DR: Basic technical aspects of immunofluorescence methods such as section cutting, substrate tissue, the purity of the fluorescein labelled antisera, and the optical properties of thefluorescence microscope, are discussed in relation to standardizing them.
Abstract: SUMMARY.– Basic technical aspects of immunofluorescence (IF) methods such as section cutting, substrate tissue, the purity of the fluorescein labelled antisera, and the optical properties of the fluorescence microscope, are discussed in relation to standardizing them. Direct and indirect fluorescence methods are mentioned.
For IF study of the skin epi-illumination has the advantage that no darkfield image of green excitation light (often still transmitted by some filter combinations) is mistaken for green FITC fluorescence. Also epi-illumination gives a better contrast and therefore it is possible to dilute the antisera and conjugates more than before to reduce non-specific staining.
The immunopathological findings in various dermatoses are briefly discussed in relation to diagnosis. Interpretation of the findings is affected by the use of a vertical illuminator with interchangeable dichroic mirrors for epi-illumination. The main finding concerns the location of Ig-complement complexes in the dermis in various dermatoses. Also the fluorescence of vessels in ‘normal’ and affected skin in various dermatoses is discussed. These include lupus erythematosus, and include results of a study of immunofluorescence and autotransplantation reactions, dermatitis herpetiformis, pemphigus vulgaris, pemphigoid, allergic vasculitis, cutaneous amyloidosis, and porphyria-erythropoietic and cutanea tarda varieties. The participation of complement in various immunological reactions is commented upon.
TL;DR: The cell envelope of Escherichia coli B was investigated with the freeze-etching technique and a considerable gain in visible structural detail over more conventional electron microscopic techniques was obtained.
Abstract: The cell envelope of Escherichia coli B was investigated with the freeze-etching technique. A considerable gain in visible structural detail over more conventional electron microscopic techniques was obtained. The inner surface of the plasma membrane revealed a smooth surface sparsely studded with particles measuring from 5 to 10 nm in diameter, whereas the outer surface of the plasma membrane showed many more particles of corresponding diameter. The freeze-etched cell wall appeared to be a multilayered structure. The innermost layer could be observed as a profile studded with closely packed elements of about 10 nm in diameter. External to this layer was a smooth surface bordering the outermost cell wall layer. When frozen in the absence of glycerol the outermost surface observed in the cell wall was smooth, but when grown in the presence of glycerol it had a “wavy” appearance with small particles attached to it. The observations support current concepts on the ultrastructure of the enterobacterial cell envelope.
TL;DR: In this paper, a planar CuCl4(NH3C3H7)2 crystallizes in the space group Pcab with cell constants a = 7.65, b = 24.66, c =7.33 A.
TL;DR: On the assumption that the glutamate dehydrogen enzyme and β-hydroxybutyrate dehydrogenase reactions are at near equilibrium, the concentrations of the components of these redox couples have been used to calculate the reduction level of intramitochondrial NAD and NADP.
TL;DR: A method for the histochemical demonstration of the activity of myosin adenosine triphosphatase in muscle tissues is described, in which the enzyme catalyzes the hydrolysis of ATP to ADP and inorganic phosphate.
Abstract: A method for the histochemical demonstration of the activity of myosin adenosine triphosphatase in muscle tissues is described. In the histochemical system the enzyme catalyzes the hydrolysis of ATP to ADP and inorganic phosphate. The incubation medium contains Ca2+-ions as activator. The enzyme localization is visualized by means of PbS. Problems involved in the histochemical demonstration of the enzyme are discussed.
TL;DR: The histochemistry of the different parts of the egg mass is compared to that of the female tract and in this way an attempt is made to elucidate the function of the various parts of this tract.
Abstract: The reproductive tract and the egg mass of Lymnaea stagnalis have been studied histologically and histochemically. The hermaphroditic duct is built up of neutral staining ciliated cells. In its distal portion the duct has large diverticula, the vesiculae seminales, which consist of large foamy cells. These cells ingest and destroy sperm. A groove with highly ciliated cuboidal or cylindrical cells is present along the length of the hermaphroditic duct. This groove is maintained throughout the greater part of the female tract, but in the male part was only observed in the prostate gland. The secretory cells of the albumen gland produce galactogen and proteins. In the rest of the female part 11 different secretory cell types could be distinguished. These cells produce different types of acid mucopolysaccharides or neutral polysaccharides. The histological findings account for 8 divisions of the female tract: 1. the albumen gland; 2. the posterior and anterior pars contorta; 3. the muciparous gland; 4. the pars recta; 5. the oothecal gland; 6. the uterus; 7. the vagina; 8. the bursa copulatrix. The histochemistry of the different parts of the egg mass is compared to that of the female tract and in this way an attempt is made to elucidate the function of the various parts of this tract. In the male part (sperm duct, prostate gland and penial complex) 13 secretory cell types were distinguished, viz., 3 in the sperm duct, 5 in the prostate gland and 5 in the praeputium. The sperm duct and the prostate gland produce mainly phospholipoproteins with some components consisting of polysaccharides and neutral fats. The function of these secretion products is assumed to be nutrition of the sperm. The secretory cells of the praeputium produce acid mucopolysaccharides, which probably play a role during copulation.
TL;DR: In this paper, a method to establish a chromatogram by pseudo random injection and cross correlation techniques is described, where it is possible to accumulate a peak from a detector output signal, buried in background noise.
Abstract: A method to establish a chromatogram by pseudo random injection and cross correlation techniques is described. It is possible to accumulate a peak from a detector outputsignal, buried in backgroundnoise.
TL;DR: It is proposed that mitochondria contain two species of cytochrome b in equal amounts, one affected by antimycin and the other not affected, and a mechanism of Site-II phosphorylation is proposed in which ATP synthesis is linked with intramolecular electron transfer within the dimer.
TL;DR: The antibiotics chloramphenicol and oxytetracycline completely blocked the formation of cytochrome c oxidase in regenerating rat liver if the serum concentration was continuously kept above 7 μg/ml serum for chlorampshenicol or 6 μg/ML for oxytettetracy Cline, and the activity of this enzyme was lower than in mitochondria from control animals.
TL;DR: In this paper, a detailed investigation of the ESR spectra of two copper centers in ammonium chloride and one copper centrum in cesium chloride crystals is presented, and an analysis of the parameters in the spin-Hamiltonian is presented.