Showing papers by "Aarhus University published in 1980"

The mathematical theory of L systems

Abstract: The paper gives a survey of the different areas of the theory of developmental systems and languages. It is organized in such a way that it discusses typical results obtained in each particular problem area. The results quoted may not always be the most important ones but they are quite representative for the direction of research in this theory. Proofs are not given and, consequently, the basic techniques for solving problems in this theory are not discussed. An attempt has been made to cover also the most recent results. Most of the results have not yet appeared in print. To appear in J. Tou (ed. ), Advances in Information Systems Science, Plenum Press.

Evidence for coexistence of dopamine and CCK in meso-limbic neurones.

Abstract: Vanderhaeghen et al. reported the occurrence of gastrin-like immunoreactivity in the mammalian brain. Subsequent studies have revealed that this immunoreactivity corresponded mainly to the COOH-terminal octapeptide of cholecystokinin (CCK-8), which has a COOH-terminal pentapeptide identical to gastrin. Also, two peptides resembling the NH- and the COOH-terminal tetrapeptide fragments of CCK-8 are present in the central nervous system (CNS). Using COOH-terminal-specific antisera raised to gastrin and/or CCK, the distribution of CCK neurones has been described with immunohistochemical techniques. Although high numbers of cells and nerve terminals are found in cortical areas, the CCK systems are also present in most other parts of the brain and spinal cord. In the CNS, true gastrin molecules, gastrin-17 and gastrin-34 have been located only in the neurohypophysis, hypothalamus and occasionally in the medulla oblongata (unpublished results). We describe here the occurrence of peptides in meso-limbic dopamine neurones in the rat brain. Evidence has also been obtained that mesencephalic dopamine neurones in the human brain contain similar peptides.

Distribution of oxygen in marine sediments measured with microelectrodes1

Abstract: . Abstract Membrane-covered platinum electrodes with a tip diameter of 2-8 pm were used for an amperometric assay of dissolved oxygen in marine sediments. The oxygen profile extended to 3-5mm depth in nonilluminated sediment; even at high light intensities and at low tem- peratures it did not extend below lo-mm depth in a homogeneous sandy sediment. Oxygen profiles recorded during light-dark cycles were used to estimate the rates of oxygen produc- tion and consumption and also to calculate the apparent diffusion coefficient for oxygen in the sediment. Apparently macrofaunal activity, rather than molecular diffusion and water turbulence, was important for the occasional transport of oxygen into deeper layers and thus for the provision of oxidized conditions (positive redox potential) down to 5-10 cm below the sediment surface.

Organization of the motoneurons innervating the pelvic muscles of the male rat.

Abstract: The cytoarchitecture of the motoneuron pool of the male rat was studied at the lumbo-sacral transition area, particularly in L6. In the latter segment a dorso-medial (DM), ventral (V), dorso-lateral (DL), and retrodorso-lateral group (RDL) could be defined. The DL group was associated with a prominent longitudinal dendrite bundle and the DM group with smaller transverse bundles. Morever, close soma-somatic apposition was found between neurons in these columns. Because L6 gives rise to n. pudendus and contributes to n. ischiadicus, horseradish peroxidase (HRP) was applied to the cut n. ischiadicus and in other experiments injected into the pelvic muscles. Neurons in RDL were labeled following exposure of n. ischiadicus to HRP. Injections in m. levator ani resulted in labeled neurons in the V group, mainly below L6. Injections in m. sphincter urethrae resulted in labeled neurons in the DL group as well as neurons immediately cranial to this column. Musculus ischiocavernosus injections resulted in transport of HRP to neurons in the DL group, primarily in its medial part, and to more cranially located neurons. In addition, some neurons in the V group in L6 were labeled. Following injections in m. bulbocavernosus and m. sphincter ani, labeled neurons were found primarily in the DM group, and to a lesser extent in the V group. Histochemical investigations with staining methods for the localization of acetyl cholinesterase (AChE) and heavy metals (the Timm method) demonstrated that part of the neuropil of DL and of DM were different from the rest of the motoneuron neuropil. In the DL group the area with the diverging staining patterns corresponded to the region of the dendrite bundle. The experimental data indicated and the ultrastructural studies demonstrated that the histochemical differences could be correlated with differences in the composition of the populations of boutons. The comparison of the cytoarchitectural and histochemical data with the results obtained by the aid of the retrograde HRP tracing technique established that mm. sphincter urethrae, ischiocavernosus, bulbocavernosus, and sphincter ani were each innervated by two populations of neurons that were situated in separate areas which had different histochemical properties, and which thus probably have different compositions of their afferent inputs. The daulity in the motoneuron pool that innervates the pelvic muscles might be a reflection of the dual influence on these muscles. As all other striated muscles the pelvic muscles are under voluntary control. However, they are also tightly linked to the function of the pelvic viscera and thus under influence of the autonomic nervous system.

Dependence of the He-Scattering Potential at Surfaces on the Surface-Electron-Density Profile

Abstract: It is shown that the repulsive part of the He-surface interaction is given by an almost linear, surface-independent function of the surface electron density at the He site. This gives a very simple connection between the measured low-energy He-beam scattering potentials and the substrate electron densities. The scheme is applied to an analysis of the He-scattering potential outside Al.

Suspension feeding in ciliated protozoa: Functional response and particle size selection.

Abstract: The quantitative uptake of latex beads of different sizes and of live cells by 14 species of ciliates was studied. The functional response (uptake rate as function of food particle concentration) can be fitted to a hyperbolic function and this can be explained in terms of the function of the mouth apparatus. Each species shows a distinct size spectrum of particles which are retained and ingested. These size spectra may be explained by mouth morphology, and particle size selection may play a role for niche separation of coexisting ciliates. Most bacterivorous holotrich ciliates retain particles down to 0.2μm and in one case down to 0.1μm; they retain particles between 0.3 and 1μm most efficiently. The spirotrich ciliates investigated do not retain particles smaller than 1–2μm.

Neural regulation of pancreatic hormone secretion by the C-terminal tetrapeptide of CCK.

Abstract: In pancreatic islets a peptide corresponding to the C-terminal tetrapeptide amide of cholecystokinin and gastrin, Trp-Met-Asp-Phe-NH2, is present in nerve terminals. This tetrapeptide amide is uniquely potent as a releaser of insulin and the other islet hormones, whereas larger cholecystokinins and gastrins as well as tetrapeptide analogues are considerably less potent. We suggest that neural release of the tetrapeptide amide is implicated in regulation of pancreatic hormone secretion.

Methotrexate induced liver cirrhosis. Studies including serial liver biopsies during continued treatment.

Abstract: SUMMARY Seven hundred and sixty-four liver biopsies were performed in 328 psoriatics on treatment with methotrexate or being considered for systemic treatment either with methotrexate or with psoralens and long-wave ultraviolet light. The diagnosis of cirrhosis was established histologically in twenty-one patients. Two patients had cirrhosis in their premethotrexate biopsy and were not given methotrexate. The remainder all showed no signs of cirrhosis or fibrosis in their premethotrexate biopsy. The difference between the methotrexate treated psoriatics and the premethotrexate group was highly significant. Among thirty-nine patients treated for more than 5 years, ten developed cirrhosis (25.6%). Almost all patients were on a divided dose intermittent oral dosage schedule. The cumulative dose of methotrexate, when cirrhosis was first found, ranged from 590 to 8105 mg, with an average dosage of 2200 mg. Other factors contributing to cirrhosis in this study seem to be previous treatment with arsenic, a previous intake of alcohol, and lowered renal function. Data on later serial biopsies from fourteen patients, of which eleven continued to receive methotrexate due to very severe psoriasis, seem to indicate that methotrexate induced liver cirrhosis is not of a very aggressive nature. When evaluated blind no progression was found in most of the later biopsies, and a ‘cumulative cirrhosis index’ composed of the combined gradings for fibrosis, assessment of membrana limitans, fibrous destruction and regeneration showed a tendency to decrease. In three patients the latest of the serial biopsies showed no cirrhosis. The observation period on continued methotrexate therapy ranged from 1 to 7 years. None of the patients with cirrhosis differed from the remaining patients on methotrexate in their laboratory results for evaluating liver damage, and apart from transient increases in serum glutamic pyruvic transaminases no abnormalities were found. The data support the necessity of liver biopsies in the control of psoriatics treated with methotrexate. Liver biopsies should be performed at least in all psoriatics in whom a cumulative dosage of methotrexate exceeds 1.5g. The data also indicate that methotrexate can be continued at least for a while in patients where the indication is strong enough, if the dosage is maintained as low as possible and alcohol consumption avoided.

β2‐ADRENOCEPTORS MEDIATE THE STIMULATING EFFECT OF ADRENALINE ON ACTIVE ELECTROGENIC NA‐K‐TRANSPORT IN RAT SOLEUS MUSCLE

Abstract: The relative role of beta 1- and beta 2-adrenoceptors in mediating the stimulating effect of adrenaline on active electrogenic Na-K-transport has been assessed in experiments on rat soleus muscles in vitro and in vivo. 2 In the rat isolated soleus muscle, adrenaline (10(-6) M) increases the resting membrane potential (EM) by 5.8 mV and stimulates 22Na-efflux and ouabain-suppressible 42K-uptake by 91 and 94%, respectively. 3 All of these effects are completely blocked by propranolol (10(-5) M), whereas the beta 1-selective adrenoceptor antagonist, metoprolol, was found to be at least 50 times less potent. 4 The beta 2-adrenoceptor agonist, salbutamol, was at least 100 times as potent as H133/22 (a beta 1-selective agonist) in stimulating 22Na-efflux and 42K-influx. 5 In experiments performed under pentobarbitone anaesthesia, the intravenous injection of adrenaline (5 microgram) or salbutamol (0.5 to 50 microgram) led to a rapid and marked increase in the EM of the exposed soleus muscle. This hyperpolarizing effect could not be accounted for by the concomitant, relatively modest change in extracellular K.

The pattern of natural size distributions

Abstract: The pattern of empirical distributions, in particular size distributions, is often best brought out by drawing a log-histogram The Gaussian or ‘normal’ distribution furnishes a description of the empirical distribution if the log-histogram approximates to a parabola In many cases, however, the log-histogram is far from parabolic but may be closely approximated by a hyperbola It is therefore natural to consider those theoretical probability distributions for which the graph of the log-probability (density) function is a hyperbola The theory and applicability of such hyperbolic distributions have been the subject of a number of recent investigations and it is the purpose of the present paper to summarize these developments, with regard to the interest they may have to sedimentologists A precise description of the hyperbolic distributions is given and their wide applicability is indicated Methods for fitting these distributions to data are discussed and a number of sedimentological examples are presented Furthermore, the question of finding dynamical explanations for the occurrence of the hyperbolic shape is considered from various points of view

Suspension feeding in ciliated protozoa: feeding rates and their ecological significance

Abstract: The quantitative uptake of suspended particles has been studied in 14 species of ciliated protozoa in terms of the maximum rate of water cleared at low particle concentrations and of the maximum ingestion rate at high particle concentrations. The results, supported by data from the literature, show that ciliates which feed on larger particles (> 1-5μm) compare favorably with metazoan suspension feeders with respect to the ability to concentrate dilute suspensions of particles. Species specialized on smaller food particles (0.2-1μm), the size range of most bacteria in natural environments, require a higher concentration of particles. Bacterial population densities which can sustain ciliate growth are found in sediments, waters rich in organic material, and in the early successional stages of decomposing organic material. This is not the case in open waters in general where bacterivorous ciliates cannot play a role as grazers of bacteria.

An increased calcium sensitivity of mesenteric resistance vessels in young and adult spontaneously hypertensive rats

Abstract: 1. We have measured the calcium sensitivity in response to noradrenaline stimulation and potassium depolarization of isolated segments of 100 to 200 micrometer mesenteric resistance vessels from spontaneously hypertensive (SHR) and control Wistar-Kyoto rats. The rats were either young (4 wk) or adult (4 months), that is of ages before or after the SHRs had developed elevated blood pressure. Experiments were performed under conditions in which the effect of noradrenaline uptake by, and the potassium-induced noradrenaline release from, the nerve terminals in the vessel walls was eliminated. 2. The response of the SHR and WKY vessels to noradrenaline under conditions where only the extracellular calcium appeared to have been removed was similar. When subsequently stimulated maximally by noradrenaline, the calcium-sensitivity of the SHR vessels (Ca-ED50 approximately or equal to 0.1 mM) was greater than that of the WKY vessels (Ca-ED50 approximately or equal to 0.2 mM). When depolarized by potassium, all vessels were less sensitive to calcium and there was little difference in the calcium sensitivity of SHR and WKY vessels in either age group (Ca-ED50 approximately or equal to 0.8 mM). 3. The results suggest that whereas the potassium (potential)-dependent calcium permeability of the SHR smooth muscle cell membrane is normal, the noradrenaline-induced calcium permeability is abnormally high. The presence of this abnormality in the vessels from the young SHRs suggests that it may be a factor involved in the aetiology of hypertension in the SHR.

Large-angle scattering of light ions in the weakly screened Rutherford region

Abstract: Total differential cross-section ratios for scattering of ${\mathrm{H}}^{+}$, ${\mathrm{He}}^{+}$, and ${\mathrm{Li}}^{+}$ ions incident on bismuth-zinc and gold-carbon systems have been measured. The energy dependence of the cross sections was measured for each species at a fixed laboratory backscattering angle (${\ensuremath{\phi}}_{\mathrm{lab}}=170\ifmmode^\circ\else\textdegree\fi{}$), using an amorphous carbon target implanted with 10-keV ${\mathrm{Zn}}^{+}$ and ${\mathrm{Bi}}^{+}$ at a depth of \ensuremath{\sim}2.7 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$. Angular distributions (${\ensuremath{\phi}}_{\mathrm{lab}}=15\ifmmode^\circ\else\textdegree\fi{}, \dots{}, 170\ifmmode^\circ\else\textdegree\fi{}$) were measured for helium ions at four different energies, using selfsupporting vacuum-deposited polycrystalline carbon and gold foils. For the case of backscattering, the cross-section ratios $\frac{{(d\ensuremath{\sigma})}_{\mathrm{Bi}}}{{(d\ensuremath{\sigma})}_{\mathrm{Zn}}}$ deviate significantly from both the Rutherford-scattering law and the Lindhard, Nielsen, and Scharff differential-scattering cross section. The deviations of the absolute cross sections from the Rutherford cross sections amount to 3.5% for 1-MeV and 16% for 0.2-MeV helium on bismuth. The experimental results are in good agreement with exact classical differential-scattering cross sections based on the Lenz-Jensen and Dirac-Hartree-Fock-Slater atomic potentials. Simple analytical formulas describing the energy and angular dependence of the cross sections are presented.

Binding of bilirubin to albumin.

Abstract: (1980). Binding of Bilirubin to Albumin. CRC Critical Reviews in Clinical Laboratory Sciences: Vol. 11, No. 4, pp. 307-399.

Characterization of a human ovarian teratocarcinoma‐derived cell line

Abstract: A cell line (PA I), derived from human ovarian teratocarcinoma cells, was obtained by culturing ascitic fluid cells from a patient with recurrence of malignant ovarian teratoma. During early passages the cultured cells showed a variable morphology, a long doubling time, and a low plating efficiency (2%). After about 50 passages in vitro, a cell population which was more homogeneous and resembled embryonal carcinoma cells were obtained. These cells had a shorter doubling time (26 h), and increased plating efficiency (77%). The early-passage cells were aneuploid (P 24) whereas the late-passage cells had a normal diploid karyotype with one balanced translocation between chromosomes No. 15 and No. 20 (P 224). Details of the karyotype suggest that the cells are heterozygous, i.e. derived from a stage before the first meiotic division. One of the two X chromosomes were inactive, and the cells expressed HLA antigens (A28 and B12), and beta 2-microglobulin. Expression of F9 antigen, characteristic of two-cell and later preimplantation embryos, was absent, while expression of PCC4 antigen, expressed also by blastocysts, was present. This finding suggests that the line might express some embryonic characteristics. The PA I cell line maintained in monolayer cultures showed several characteristics of malignant cells. The proportion of malignant cells increased with successive passages in vitro. The late-passage cells represented a fairly homogenous population of malignant cells similar to embryonal carcinoma cells. Late-passage PA I cells, when seeded under conditions that prevented attachment of cells to the substratum, formed embryoid bodies consisting of an inner core of cells similar to embryonal carcinoma cells, surrounded by a rind of endoderm-like cells. These two cell layers were separated by a basement membrane-like structure containing fibronectin. The core embryonal carcinoma cells expressed high alkaline phosphatase activity whereas the endoderm-like cells had low alkaline phosphatase activity. Embryoid bodies seeded on an adhesive substratum formed polycystic structures divided by layers of epithelial-like cells and containing extracellular fibrils similar to collagen type I or III. In these cultures, further limited differentiation into endoderm-like, epithelial-like cells and pigmented cells was observed. Morphological differenciation of undifferentiated PA I cells into endoderm-like cells in monolayer cultures could be obtained by treatment with BrdUrd or by plating in low serum concentration and at low density. Cells with characteristic fibrillar distribution of fibronectin and actin microfilament bundles were then observed, indicating formation of cells lacking properties of malignant cells. As indicated by these results, the PA I cell line, in spite of a limited capacity to differentiate in vitro, shares some of the properties of mouse teratocarcinoma cell lines and might therefore serve as a useful model for studies on some developmental mechanisms in human cells.

Cortical interstitial tissue and sclerosed glomeruli in the normal human kidney, related to age and sex. A quantitative study.

Abstract: The relative amount of interstitial cortical tissue was measured by the point count method in kidney tissue from human individuals without renal disease. One series (54 kidneys) consisted of kidneys intended for transplantation and removed immediately after death from persons who died suddenly. The other series (69 kidneys) was obtained by autopsy. In both groups, the percentage of interstitial tissue was dependent on age and followed the equations of regression (1) y = 12.45 + 0.11 0.11 x (donor series) and (2) y = 23.8 + 0,10 x (autopsy series). The autopsy values were significantly greater than the donor-kidney-values. There was no difference due to sex. The relative number of sclerotic, obsolescent glomeruli was very small (0-1%) until the age of 40. Thereafter it increased, most markedly in the autopsy series, until it reached values of about 30% in persons more than 80 years old.

Relation between particle size selection and clearance in suspension‐feeding ciliates

Abstract: Suspension-feeding, ciliated protozoans retain particles by sieving the feeding currents through ciliary organelles and show well-defined size spectra with respect to the particles retained and ingested. When different species of ciliates are compared, clearance is correlated with the particle size most efficiently retained. Thus, species specialized on particles of bacterial dimensions (0.2–1 µm) have a strongly reduced clearance, due to a decreased rate of water propulsion through the filter, from that of species specialized on larger food particles. It is suggested that this is related to the increased resistance to water flow in filters with a decreasing porosity, since cilia can only generate a small hydrostatic pressure. Ciliary suspension feeders specialized on small particles have relatively high requirements with respect to the minimum food particle concentration; they could not maintain populations at bacterial concentrations typical of offshore waters.

The Complete Amino‐Acid Sequence of Elongation Factor Tu from Escherichia coli

Abstract: The complete primary structure of elongation factor Tu from Escherichia coli has been elucidated. The protein, which is a mixture of two gene products, consists of a single polypeptide chain of 393 residues. After tryptic digestion of S-carboxymethylated protein, 50 tryptic peptides were isolated covering the complete protein chain. Their alignment was established with overlapping peptides obtained by chemical cleavage with cyanogen bromide and subsequent enzymic subdigestion with Staphylococcus aureus protease, chymotrypsin, elastase and thermolysin. Peptides were sequenced by manual dansyl-Edman and direct Edman degradation procedures. The N-terminal amino acid of EF-Tu is serine and is N-acetylated. The lysine residue at position 56, in the polypeptide chain is partly methylated. The C-terminal residue is a mixture of serine and glycine, and this was the only heterogeneity found in the EF-Tu preparation used in this study.

Clinically significant side effects of lithium treatment A SURVEY OF 237 PATIENTS IN LONG‐TERM TREATMENT

Abstract: A group of 237 patients in long-term lithium treatment were questioned specifically about five side effects commonly associated with lithium treatment and unspecifically about “other” complaints. About one tenth of the patients did not complain of side effects, two thirds had one or two complaints, and one fourth had three or more. About one half of the patients complained of hand tremor, two thirds of increased thirst, one fifth of weight gain exceeding 10 kg, one fifth of diarrhea, and one tenth of edema of legs or face. A few patients had other complaints. For each side effect we analysed whether its presence was significantly associated with such patient and treatment variables as sex, age, duration of the lithium treatment, 12-h serum lithium concentration, type of lithium preparation, and additional medication. Men complained of tremor significantly more often than women. Diarrhea was significantly less frequent in patients given additional treatment with antidepressants. Weight gain was associated with increased thirst and fluid output and with significantly increased blood pressure. None of the other variables distinguished between patients with and without the various complaints. We nevertheless hypothesize that a moderate reduction of the serum lithium level may lead to a lowering of the frequency of some side effects.