Showing papers by "Aarhus University published in 1981"

Histochemical demonstration of heavy metals. A revised version of the sulphide silver method suitable for both light and electronmicroscopy

Abstract: The three steps of the sulphide silver method have been examined: 1) Transformation of metals to metal sulphides; 2) Fixation and embedding or freezing of the tissue for sectioning; and 3) Deposition of metallic silver on the metal sulphides in a physical developer. Based on the results, a revised method is described and discussed. It is particularly important 1) To maintain a sufficient but low concentration of sulphide ions during the perfusion; 2) To avoid using oxidating or acid fixatives; 3) To ensure low temperatures while embedding in paraffin or during polymerization of Epon; and 4) to use a slow-acting physical developer. Examples of the metal sulphide pattern from various tissues are presented.

Localization of gold in biological tissue. A photochemical method for light and electronmicroscopy.

Abstract: A detailed description is given of a method by which gold can be visualized in frozen, paraffin and Epon sections. Histological sections from animals treated with gold compounds are exposed to UV-light from 30 min to several hours. The reduced, metallic gold is then visualized by means of a photographic developer containing silver lactate. Light- and electronmicroscope photographs showing gold in different organs from rats and mice treated with aurothioglucose, aurothiosulfate and aurothiomalate are presented.

Volatile Fatty Acids and Hydrogen as Substrates for Sulfate-Reducing Bacteria in Anaerobic Marine Sediment

Abstract: The addition of 20 mM MoO42− (molybdate) to a reduced marine sediment completely inhibited the SO42− reduction activity by about 50 nmol g−1 h−1 (wet sediment). Acetate accumulated at a constant rate of about 25 nmol g−1 h−1 immediately after MoO42− addition and gave a measure of the preceding utilization rate of acetate by the SO42−-reducing bacteria. Similarly, propionate and butyrate (including isobutyrate) accumulated at constant rates of 3 to 7 and 2 to 4 nmol g−1 h−1, respectively. The rate of H2 accumulation was variable, and a range of 0 to 16 nmol g−1 h−1 was recorded. An immediate increase of the methanogenic activity by 2 to 3 nmol g−1 h−1 was apparently due to a release of the competition for H2 by the absence of SO42− reduction. If propionate and butyrate were completely oxidized by the SO42−-reducing bacteria, the stoichiometry of the reactions would indicate that H2, acetate, propionate, and butyrate account for 5 to 10, 40 to 50, 10 to 20, and 10 to 20%, respectively, of the electron donors for the SO42−-reducing bacteria. If the oxidations were incomplete, however, the contributions by propionate and butyrate would only be 5 to 10% each, and the acetate could account for as much as two-thirds of the SO42− reduction. The presence of MoO42− seemed not to affect the fermentative and methanogenic activities; an MoO42− inhibition technique seems promising in the search for the natural substrates of SO42− reduction in sediments.

Synthetic Differential Geometry

Abstract: Preface to the second edition (2005) Preface to the first edition (1981) Part I. The Synthetic Ttheory: 1. Basic structure on the geometric line 2. Differential calculus 3. Taylor formulae - one variable 4. Partial derivatives 5. Taylor formulae - several variables 6. Some important infinitesimal objects 7. Tangent vectors and the tangent bundle 8. Vector fields 9. Lie bracket 10. Directional derivatives 11. Functional analysis - Jacobi identity 12. The comprehensive axiom 13. Order and integration 14. Forms and currents 15. Currents - Stokes' theorem 16. Weil algebras 17. Formal manifolds 18. Differential forms in terms of simplices 19. Open covers 20. Differential forms as quantities 21. Pure geometry Part II. Categorical Logic: 1. Generalized elements 2. Satisfaction (1) 3. Extensions and descriptions 4. Semantics of function objects 5. Axiom 1 revisited 6. Comma categories 7. Dense class of generators 8. Satisfaction (2) 9. Geometric theories Part III. Models: 1. Models for axioms 1, 2, and 3 2. Models for epsilon-stable geometric theories 3. Well-adapted models (1) 4. Well-adapted models (2) 5. The algebraic theory of smooth functions 6. Germ-determined T-infinity-algebras 7. The open cover topology 8. Construction of well-adapted models 9. Manifolds with boundary 10. Field property - germ algebras 11. Order and integration in cahiers topos Appendices Bibliography Index.

Immunohistochemical studies on the effect of capsaicin on spinal and medullary peptide and monoamine neurons using antisera to substance P, gastrin/CCK, somatostatin, VIP, enkephalin, neurotensin and 5-hydroxytryptamine.

Abstract: After neonatal treatment of rats with capsaicin, the spinal cord, the spinal trigeminal nucleus and spinal and trigeminal ganglia were analysed with immunohistochemistry using antisera to several peptides and 5-hydroxytryptamine. A marked decrease was observed in substance P-, cholecystokinin-, somatostatin- and VIP-like immunoreactivity present in the central branches of primary sensory neurons in the spinal cord and in substance P- and somatostatin-like immunoreactivity in sensory ganglion cells. No definite depleting effect of capsaicin could be established on 5-hydroxytryptamine and peptides, such as enkephalin and neurotensin, present in centrally originating fibres in the dorsal horn of the spinal cord. The results demonstrate that the effects of capsaicin are not confined to substance P immunoreactive primary sensory neurons. The possibility is discussed that capsaicin effects specifically functioning rather than chemically specific primary sensory neurons.

A Consecutive 7-Year Series of 1331 Benign Soft Tissue Tumours: Clinicopathologic Data. Comparison with Sarcomas

Abstract: A consecutive 7-year series of 1331 benign soft tissue tumours was analysed and compared with the data of 72 sarcomas diagnosed in the same period (April 1970 to April 1977). Lipoma was the most frequent benign tumour entity, accounting for almost half of the entire series. Different entities had different male to female ratios and preferred locations and, furthermore, differed from sarcomas in this regard. The factors which discriminated most in the clinical differential diagnosis benign vs. malignant were tumour size and location.At the first visit to the general practitioner or surgeon it is recommended that patients with large (≥50 mm) and/or deep seated tumours (beneath or fixed to superficial fasciae) or tumours obviously malignant for other reasons (invasion of nerves, vessels or bone) should be transferred, leaving their tumours untouched, to a centre for soft tissue sarcomas for further diagnosis and treatment.

Primary production of microalgae in sediments measured by oxygen microprofile, H14CO3 ‐ fixation, and oxygen exchange methods1

Abstract: A platinum microelectrode was used to measure changes in dissolved oxygen profiles in surface sediment exposed to light and darkness. Estimates of production by microalgae thus derived were compared with those derived from conventional methods of measuring changes in dissolved oxygen and H14C0,- uptake. For each particular depth in the sediment, the primary production can be determined within a few seconds by the new method. Undisturbed sediment cores were used for the H14C0,- fixation assay of benthic photosynthesis. Measurements of the specific activity of HC03- within the photic zone showed a steep gradient of IP”CO,- at the sediment surface. Calculations of benthic photosynthesis taking the actual specific activity into account yielded 2-5 times higher estimates than calculations using the specific activity in the overlying water. In a highly oxidized sediment, the three methods yielded almost identical results at low light intensities (200 pEinst*m-2*s-1). The oxygen methods grossly underestimated the primary productivity at higher light intensities, due to bubble formation. The conventional oxygen method grossly underestimated the primary productivity in sulfuretm~r-type sediments as compared to the two other methods. In addition to photosynthesis, the oxygen consumption by the sediment was determined by oxygen microprofiles.

Phytoplankton and Epiphyte Development and Their Shading Effect on Submerged Macrophytes in Lakes of Different Nutrient Status

Abstract: The annual mean light intensity at the depth limit of the Littorella vegetation was 24–33% of the subsurface light intensity, despite large variations in each attenuation component (lake water, phytoplankton, and epiphytes). In oligotrophic, silicate-poor lakes, the light attenuation above the submerged vegetation was dominated by the water itself, which accounted for 65–72% of the total attenuation. Phytoplankton and epiphytes were equal in importance to each other. In oligotrophic, silicate-rich lakes and lakes receiving a nitrogen supply above background level, the epiphytes were more abundant, accounting for about 50% of the light attenuation. In one lake with a high nutrient supply, the epiphytes were responsible for 86% of the light attenuation. A new method of measuring the effect of shading by the epiphytic community on submerged macrophytes is presented. The light attenuation caused by the phytoplankton and the epiphytes was investigated and related to the depth distribution of the submerged angiosperm, Littorella uniflora. It is shown that the biomass of the epiphytes increased more than the biomass of the phytoplankton in response to an external or internal nutrient loading. Shading by epiphytes is of decisive importance for the depth distribution of Littorella at increasing nutrient supply.

Lesion-induced sprouting of hippocampal mossy fiber collaterals to the fascia dentata in developing and adult rats.

Abstract: A lesion-induced formation of an abnormal projection of hippocampal mossy fiber collaterals to the molecular layer of the fascia dentata was studied in rats. Both immature (1--30 days old) and adult rats were subjected to hippocampal and entorhinal lesions which alone or in combination removed one or more of the major afferents to the dentate molecular layer (commissural, associational, and perforant path). Some lesions in addition transected the main part of the mossy fibers en route from the dentate granule cells to the hippocampal pyramidal cells in regio inferior (CA3). The formation of aberrant mossy fiber terminals in fascia dentata (supragranular mossy fibers) was monitored by the histochemical Timm sulphide silver method, but the presence of aberrant terminals was also observed in the electron microscope. Abnormal amounts of supragranular mossy fiber terminals were found following entorhinal lesions of both immature and adult rats, but not following commissural lesions. Even larger amounts of aberrant terminals were, however, found in immature and adult rats subjected to lesions which removed most of the associational hippocampodentate projection by isolating columns of fascia dentata from major parts of the hilus (CA4). Pure transections of the fascia dentata perpendicular to its longitudinal septotemporal axis did not in itself cause aberrant supragranular terminals, although such lesions partially damaged the associational afferents. When the transections were combined with commissural lesions or entorhinal lesions or both, large amounts of supragranular terminals did, however, form at the denervated levels septal to the transection. After comparison of the amounts and distributions of the aberrant terminals found after the different lesions and in transplants of dentate tissue with different amounts of afferent input, we conclude that it is deafferentation of the dentate molecular layer, and not axotomy of the mossy fibers in the hilus of CA3 (pruning), that causes the aberrant growth of mossy fiber collaterals. Moreover, simultaneous removal of more than one afferent system seems to have a potentiating rather than a simple additive effect on the formation of supragranular mossy fibers.

Clonal Growth of Epithelial Cells from Normal Adult Human Bronchus

Abstract: Normal primary epithelial cell cultures devoid of fibroblastic cells have been developed from tissue explants of adult human bronchi. Conditions for clonal growth of secondary cultures of bronchial epithelial cells were optimized by coculturing the human cells with mitomycin C growth-arrested Swiss 3T3 mouse feeder cells, lowering the calcium concentration of medium M199, and supplementing it with hydrocortisone, insulin, cholera toxin, epidermal growth factor, and 1.25% fetal bovine serum. The epithelial cells grew for an average of 35 population doublings and had the normal human karyotype, expressed keratin and blood group antigen epithelial cell markers, metabolized benzo(a)pyrene, and were capable of differentiating into both ciliated and squamous cells. This culture system makes it potentially possible to investigate various aspects of differentiation and carcinogenesis in human bronchial epithelial cells.

Cycles in digraphs– a survey

Abstract: The main subjects of this survey paper are Hamitonian cycles, cycles of prescirbed lengths, cycles in tournaments, and partitions, packings, and coverings by cycles. Several unsolved problems and a bibiligraphy are included.

Light and electron microscopic localization of silver in biological tissue.

Abstract: A method is described that visualizes trace amounts of silver in frozen, paraffin and epon sections from biological tissue. After exposure to light, which ensures reduction of silver ions that are not bound to sulphide, histological sections from animals treated with silver compounds are exposed to a photographic developer containing silver ions. Tissue silver acts as a catalyst for the hydroquinone reduction of silver ions to metallic silver which then accumulates at the site of the trace deposit. Light and electron micrographs showing silver in different organs from albino rats treated with silver lactate are presented. Localization of silver in motor neurons of the spinal gray matter and pons indicates a transport of silver over the blood-brain barrier. Silver precipitates in fetal liver suggest that silver ions can penetrate the placental barrier.

Hyperbolic Distributions and Ramifications: Contributions to Theory and Application

Abstract: The characteristics of the one-dimensional generalized hyperbolic distributions are discussed, and the questions of maximum likelihood estimation for the hyperbolic distribution are considered in some detail. Various ways of approximating a theoretical distribution by one of the hyperbolic or generalized hyperbolic distributions are outlined and as an application of this an approximation is obtained to the distribution of the sum of a sample of observations from the hyperbolic distribution.

A Preliminary Survey of the Theories and Findings on Vote and Popularity Functions

Abstract: The survey covers the rapidly growing body of literature on party-support models estimated on time series data for elections and popularity polls. The movements in the popularity of the parties are explained by their government participation and, mainly, the economic conditions as measured by the standard macroeconomic indicators. Sections 1 and 4 present the central qualitative findings and ideas of about 50 of the most important articles and conclude that the economic indicators explain around 1/3 of the variations in the party popularities; the main drawback of the models is their lack of stability. The remaining Sections—2 and 3 - discuss the theory behind the models and some of the theoretical implications of the findings. That is, the problems involved in an adequate representation of the political factors; the time horizons at play; the relations to the micro theory of voting and the social welfare function; the formations of the expectations relevant and how people perceive the economy.

Rates of nitrification, distribution of nitrifying bacteria, and nitrate fluxes in different types of sediment from Danish waters

Abstract: Nitrification rates, measured in different sediment types from Danish waters, are in the range of 0.3 to 1.4 mmol NO 3 - m-2 d-1. There is no signification between sandy and muddy sediments, nor between shallow and deeper stations. The extent of nitrification is probably limited to the zone of oxygen penetration, 1.5 to 5.5 mm. There are, however, nitrifying bacteria located in the anoxic sediment layers. There relative numbers were found by measuring the “nitrification potential” of the sediment. These potential rates (22°C) can also be used to calculate actual rates of nitrification, by adjusting to in situ temperature and oxygen penetration. These calculated rates agree with the actual measured rates of nitrification for a wide range of sediment types and may be used for the estimation of actual nitrification rates. Nitrate flux out from the sediment/water interface is in the range of 0 to 0.7 mmol NO 3 - m-2 d-1. There is no correlation between concentration gradients of nitrate across the sediment/water interface and the measured flux of nitrate. Approximately 50% of nitrate production is released to the water column. The remainder (0 to 0.35 mmol N m-2 d-1) may have been denitrified.

Pharmacokinetics of amiodarone after intravenous and oral administration

Abstract: Seven patients with cardiac arrhythmias were given amiodarone 400 mg intravenously over 2 min, and 2–4 days later the same dose was given orally. The serum concentration of amiodarone was determined by HPLC; the sensitivity of the analysis was 0.1 µg/ml. The time sequence of the measurements of drug concentration made conventional compartemental analysis impossible. There was large individual variation but some of the curves suggested enterohepatic circulation. The time from oral intake to the peak serum concentration was estimated to be 7.3±2.9 h (SD). The “amount of drug reaching the general circulation in 24 h after oral intake” averaged 42% (22–80%). After oral administration of amiodarone 200 mg 8 hourly the serum concentration before the morning dose averaged 0.61 µg/ml after 24 h, 0.76 after 48 h, 1.18 after 1 week and 1.56 µg/ml after 1 month. In one patient, who had been on amiodarone therapy for 8 months, the drug was discontinued and the serum concentration was followed over the next 3 months. The drug elimination curve suggested an elimination half life of 13.7 days. Because of instability in physiological saline protein binding could not be precisely quantitated, but only characterized as strong. No unchanged amiodarone was found in urine. The urinary excretion of iodine over 2 h after intravenous administration suggested that 5% of orally administered amiodarone was eliminated in the urine after biotransformation. No effect of the drug was observed during the first 10 days of treatment. In 2 patients with supraventricular arrhythmia, an excellent response was seen, and in one with ventricular arrhythmia there was a good response.

Single-electron-capture cross section for medium- and high-velocity, highly charged ions colliding with atoms

Abstract: Experimental cross sections for single-electron capture for medium- to high-energy, highly charged oxygen and gold ions colliding with helium atoms are presented. Simple estimates based on the classical cross sections introduced by Bohr and Lindhard for multiply charged ions are shown to lead to good first approximations of the absolute magnitude of the cross sections for any target atom. Furthermore, these estimates suggest a universal scaling of the capture cross sections with ion and target-atom parameters. The experimental results of this work as well as those obtained by other groups are shown to be in accordance with the suggested scaling laws, which are also supported by the results of the few more-refined theoretical treatments that have been published.

Comparison of semiautomatic digitizer-tablet and simple point counting performance in morphometry

Abstract: A comparison is made between the efficiency of an opto-manual digitizer-tablet (MOP-AM 03) and simple point counting in the analysis of drawings of basal cells in the normal and pathologically altered chonchal epithelium. The analysis included estimation of the areas of cellular, nuclear and nucleolar sectional profiles as well as the cell basal width, i.e. the length of cell profile attachment to the basement membrane. The morphometric results obtained with the two methods are virtually identical. The efficiency of point counting is somewhat higher than that of the digitizer, but the prices of the two sets of equipment differ by one or two orders of magnitude. In general, the unquestionable measuring precision of the digitizer is unlikely to be of much impact in most biological studies due to the inevitable biological variation between individuals under study and the large variation which is always added at the level of single features by random sectioning.

The structure of a chromosomal leghaemoglobin gene from soybean

Abstract: Leghaemoglobin (Lb) has only been found in the nitrogen-fixing root nodules of legumes symbiotically associated with Rhizobia. Soybean nodules contain three major forms of Lb called a, c1 and c2, respectively. The amino acid sequences of the three Lbs have been determined recently1. Lb a differs from the two c varieties in six amino acids, while Lb c1 and c2 differ in only one amino acid. We have recently reported the isolation of a hybrid plasmid containing soybean Lb cDNA sequences2. Using one such clone as a probe, we have isolated five different soybean DNA fragments containing chromosomal Lb genes from a soybean DNA library which was constructed using lambda λgt Wes·λB as vector. The detailed analysis of one of the isolated chromosomal Lb genes revealed the presence of three intervening sequences. Alignment by homology of all known globin amino sequences shows that the splicing points of the first and the third intervening sequences in the Lb-coding sequence are located in the same positions as the two interruptions found in all other known globin-coding sequences.