Showing papers by "Aarhus University published in 1988"

Some new, simple and efficient stereological methods and their use in pathological research and diagnosis.

Abstract: Stereology is a set of simple and efficient methods for quantitation of three-dimensional microscopic structures which is specifically tuned to provide reliable data from sections. Within the last few years, a number of new methods has been developed which are of special interest to pathologists. Methods for estimating the volume, surface area and length of any structure are described in this review. The principles on which stereology is based and the necessary sampling procedures are described and illustrated with examples. The necessary equipment, the measurements, and the calculations are invariably simple and easy.

Multiparty unconditionally secure protocols

Abstract: Under the assumption that each pair of participants can communicate secretly, we show that any reasonable multiparty protocol can be achieved if at least 2n/3 of the participants are honest. The secrecy achieved is unconditional. It does not rely on any assumption about computational intractability.

Microalbuminuria: a major risk factor in non-insulin-dependent diabetes. A 10-year follow-up study of 503 patients

Abstract: The impact of microalbuminuria on mortality as well as other risk factors was investigated in a 10-year follow-up study of 503 predominantly non-insulin-dependent diabetic patients of whom 265 had died. Using Cox's regression analysis the prognostic influence of age, sex, age at diagnosis, known diabetes duration, blood pressure, fasting plasma glucose, relative weight, serum creatinine, retinopathy, and treatment was evaluated as well as morning urine albumin concentration (UAC) in four categories, i.e. UAC less than or equal to 15 micrograms/ml (normal), 15 micrograms/ml less than UAC less than or equal to 40 micrograms/ml, 40 micrograms/ml less than UAC less than or equal to 200 micrograms/ml and UAC greater than 200 micrograms/ml. Age, UAC, known duration, and serum creatinine were the only significant risk factors. After correction for the other three independent risk factors, the hazard ratios in the elevated UAC categories relative to the group with UAC less than or equal to 15 micrograms/ml were 1.53 (p = 0.007), 2.28 (p = 0.000002), and 1.82 (p = 0.02). The statistically significant correlations with UAC were: age (r = 0.09, p less than 0.05), duration (r = 0.14, p less than 0.01), systolic blood pressure (r = 0.12, p less than 0.01), serum creatinine (r = 0.33, p less than 0.001), and fasting plasma glucose (r = 0.12, p less than 0.01). Increased UAC was associated also with retinopathy (p = 0.01). Fifty-eight per cent of the deaths were caused by cardiovascular disease or stroke; only 3% died from uraemia. A reinvestigation including blood pressure, fasting plasma glucose, and UAC was made on 208 survivors.

Structural basis for E1-E2 conformational transitions in Na,K-pump and Ca-pump proteins.

Abstract: The primary active transport of Na +, K +, Ca 2T and H + in eukaryotic cells is driven by ATP-powered cation pumps, the Na,K pump, Ca pump and H,K pump. The intermediary steps of the pump reactions and their relationship to cation translocation have been examined in detail, particularly for the Na,K-pump and Ca-pump proteins. A common feature of these pumps is a protein of Mr close to 110,000 that binds ATP and accepts its y-phosphate in a covalent Asp-P bond. There is evidence that both phosphoand dephospho-forms of the protein exist in two major conformational states, E1 and E2, with different affinities and orientation of cation binding sites, and ATP-driven cation pumping is blocked by micromolar concentrations of vanadate [39, 68, 95, 96, 116, 132]. A wealth of structural information about the cation pump proteins appeared recently after identification of mRNA and sequencing of cloned cDNA. Several isoforms of the genes of o~-subunit of Na,K pump were identified in the human and rat genomes [147, 182] and the sequences ofa-subunit [110, 111,145, I46, 178,181] and B-subunit [22, 112, 140, 146, 179] were deduced from cDNA of mRNA from a variety of tissues in piscine and mammalian species. A similar intensity of work in adjacent fields provided the sequences of slow and fast twitch Ca pump from sarcoplasmic reticulum [19, 121] and H,K pump from stomach mucosa [180]. In addition the gene sequences are available for K pumps [82, 185] and H pumps [1, 177] from microorganisms. As paradigm for interpretation of this information the combined X-ray crystallographic structure at high resolution and

An introduction to event structures

Abstract: Event structures are models of processes as events constrained by relations of consistency and enabling. These notes are intended to introduce the mathematical theory of event structures, show how they are related to Petri nets and Scott domains, and how they can be used to provide semantics to programming languages for parallel processes as well as languages with higher types.

Payment Systems and Credential Mechanisms with Provable Security Against Abuse by Individuals

Abstract: Payment systems and credential mechanisms are protocols allowing individuals to conduct a wide range of financial and social activities while preventing even infinitely powerful and cooperating organizations from monitoring these activities. These concepts were invented and first studied by David Chaum.Clearly, such systems must also be secure against abuse by individuals (prevent them from showing credentials that have not been issued to them, etc.). In this work, we present constructions for which we can prove, that no individual can cheat successfully, unless he possesses an algorithm that contradicts a single plausible intractability assumption. This can be done while maintaining the unconditional security against abuse by organizations.Our constmction will work using any general two-party computation protocol with unconditional privacy for one party, and any signature scheme secure against adaptive chosen message attacks (these concepts are explained in more detail later). From the signature scheme by Bellare and Micali [BeMi] and the multiparty computation protocol by Chaum, Damgard and van de Graaf [ChDaGr], it will be clear that both requirements can be met if pairs of claw free functions and trapdoor one-way permutations exist. This, in turn, is satisfied, for example if factoring Blum integers is a hard problem.For credential mechanisms, we obtain an additional advantage over one earlier proposals [ChEv], where a center trusted by the organizations (but not by individuals) was needed. This center possessed a "master" secret allowing it to issue all types of credentials supported by the system. Moreover, the center had to be on-line permanently. In our construction, only an off-line center is needed, which only has to be trusted as far as validating the identity of each individual is concerned. Only organizations authorized to issue a given type of credential have the ability to compute them.

Improvement of psoriasis by a topical vitamin D3 analogue (MC 903) in a double-blind study.

Abstract: The effect of the non-calciotropic vitamin D3 analogue MC 903 on psoriasis vulgaris was assessed in a double-blind, placebo controlled trial in 30 patients. Lesions on one side of the body were treated for 6 weeks with a cream containing 10 μ/g, 33 μg//g or 100 μg/g MC 903 and lesions on the other side were treated with the cream base alone, according to a randomized design. Nine of the 10 patients in each treatment group completed the study. MC 903 cream gave a statistically significant decrease in erythema, thickness and scaling of the lesions, compared with the control. Overall assessment of psoriasis after 6 weeks showed moderate or excellent improvement in two of nine patients treated with 10 μg/g, in five of nine patients treated with 33 μ/g, and in seven of nine patients treated with 100 μ/g MC 903. Placebo treatment showed a moderate improvement in only one of the 27 patients. The histopathological picture of the psoriatic lesions corresponded with the clinical changes. The patients reported no adverse reactions, and laboratory tests did not show any significant changes; in particular there was no change in serum calcium levels. These results suggest that the vitamin D3 analogue MC 903 is an effective and safe topical treattnent for psoriasis.

Analytical Calculation of Geometrical Derivatives in Molecular Electronic Structure Theory

Abstract: Publisher Summary This chapter reviews the techniques recently available for the analytical calculation of molecular energy and property derivatives. The chapter focuses on the techniques that are simple and general, in particular those which can handle large basis sets and configuration expansions. It presents derivative expressions for most commonly used methods in molecular electronic structure theory, and their computational implementations. It is seldom possible to give expressions that are optimal under all conditions, regardless of the number of electrons, basis functions, and configurations. The analytical calculation of energy derivatives has recently been reviewed by Pulay and Gaw and Handy and the analytical calculation of property derivatives by Amos. The development of and computational implementation of analytical expressions for the derivatives of ab initio electronic energy surfaces and molecular properties have undergone rapid growth in recent years. This growth reflects the central role these derivatives play in understanding chemical reactions and in interpreting many spectroscopic experiments. The approach taken in this chapter constitutes a good basis for developing efficient procedures for calculation of geometrical derivatives under any particular set of circumstances.

Facilitation of a dendritic calcium conductance by 5-hydroxytryptamine in the substantia nigra.

Abstract: Within the substantia nigra, the dendrites of dopaminergic neurons that project to the striatum appear to play an active and nonclassical role in the physiology of the neuron in that they release transmitter and protein, but little is known of the factors controlling release of substances from these dendrites In this study, we show that 5-hydroxytryptamine, which is contained in afferent fibres to the substantia nigra, is present in terminals making direct synaptic contact with dopaminergic neurons and also that it has a site-dependent, receptor-mediated, facilitatory effect on a specific dendritic calcium-dependent potential in nigrostriatal neurons in vitro The ionic and spatial features of this response, which is insensitive to blockade by three different K+-channel antagonists, could correspond to those underlying the dendritic release of dopamine

The relationship between interictal and ictal paroxysms in an in vitro model of focal hippocampal epilepsy.

Abstract: In studies of focal epilepsy it is frequently assumed that the interictal spike is the elementary form of epileptic activity and that seizure, or ictal, episodes evolve by temporal summation and spatial expansion of interictal paroxysms. We examined this hypothesis in an in vitro model of acute focal epilepsy produced by perfusing rat hippocampal slices with solutions containing moderately elevated concentrations of K+. Some of the preparations treated in this way displayed recurring electrical seizures in the CA1 field. Each seizure episode typically evolved by a seemingly smooth progression of brief interictal bursts into sustained ictal discharge. However, exposure of preparations showing electrical seizures to blockers of synaptic transmission or to cholinergic agonists abolished interictal spiking in all hippocampal fields but did not impede the initiation of ictal episodes in area CA1. Likewise, severing the connections between areas CA3 and CA1 abolished interictal spiking in area CA1 without disrupting the initiation of seizures in this region. These data clearly show that in this model, focal seizures arise independent of interictal spikes and through different cellular mechanisms. While interictal electrogenesis requires chemical synaptic excitation, ictal episodes can be initiated and maintained by nonsynaptic neuronal interactions.

Psychological Weil‐Being Among Unemployed and Employed People After a Company Closedown: A Longitudinal Study

Abstract: In a three-year longitudinal study, we examined the effects of unemployment and the fear of becoming unemployed on the psychological well-being of 1153 employees at a shipyard that was closed down, and a control group of 441 employees from another, operative shipyard. On all three questionnaires, unemployed people were significantly lower in psychological well-being than employed people. Change to or from employment was significantly associated with changes in psychological well-being, whereas remaining employed or unemployed did not lead to any systematic changes in psychological well-being. Among employed people, the fear of unemployment was strongly associated with reduced psychological well-being. Thus, the health-related consequences of unemployment affect not only the unemployed but also employed people who have little job security. Consequently, we stress the need to create new workplaces and to implement reforms that can reduce job insecurity in the labor market.

Interaction of a nodule specific, trans-acting factor with distinct DNA elements in the soybean leghaemoglobin Ibc(3) 5' upstream region.

Abstract: Nuclear extracts from soybean nodules, leaves and roots were used to investigate protein-DNA interactions in the 5' upstream (promoter) region of the soybean leghaemoglobin lbc(3) gene. Two distinct regions were identified which strongly bind a nodule specific factor. A Bal31 deletion analysis delimited the DNA elements responsible for the binding of this factor, which map at nucleotides -223 to -246 (element 1) and -161 to -176 (element 2), relative to the start point of transcription. Competition experiments strongly suggest that both elements bind to the same nodule specific factor, but with different affinities. Elements 1 and 2 share a common motif, although their AT-rich DNA sequences differ. Element 2 is highly conserved at an analogous position in other soybean lb gene 5' upstream regions.

Continental Heat-Flow Density

Abstract: Although on the geological time and space scales the geothermal regime of the Earth is, strictly speaking, both a transient and three dimensional phenomenon, on the global scale by far the most important component of heat transfer is radial. Furthermore, over times of the order of the thermal time constant for the crust, that is a few hundred thousand to a few million years, we consider the thermal regime to be quasi-steady state.

Prospective studies on a lithium cohort. 3. Tremor, weight gain, diarrhea, psychological complaints.

Abstract: A cohort of manic-depressive patients given prophylactic lithium treatment were examined before treatment started and at intervals during treatment for up to 7 years. The mean lithium dosage was 23.2 mmol/d and the mean serum lithium concentration 0.68 mmol/l. About 40% of the patients were entirely free of side effects, as compared with 10% among patients treated previously with higher lithium doses and serum lithium concentrations. Tremor complaints were presented by 5% of the patients before and by 15% during lithium treatment. The frequency fell with continued treatment, and after a few years it was not higher than before treatment started. Tremor complaints were positively correlated with age and with the use of neuroleptics and antidepressants. The tremorigenic effects of lithium and antidepressants seemed to potentiate each other. Tremor complaints were more frequent at serum lithium levels over than under 0.7 mmol/l. Body weight increased during the first 1-2 years of lithium treatment and then remained constant. The average gain was 4 kg. Weight gain was positively correlated with the patients' body weight before treatment and with the concurrent administration of antidepressant drugs. The frequency of diarrhea complaints (loose stools, defecation urge) rose from 1% to 6% during the first 6 months of lithium treatment and then leveled off. The frequency rose steeply at serum lithium values over 0.8 mmol/l. During lithium administration about one tenth of the patients had psychological complaints, which might or might not have been caused by the treatment: memory impairment and concentrating difficulty, tiredness and "greyness of life", in a few cases altered taste or lowered libido and potency.

On the level-error after Bartlett adjustment of the likelihood ratio statistic

Abstract: SUMMARY It is well known that Bartlett adjustment reduces level-error of the likelihood ratio statistic from order n-l to order n3/2. In the present note we show that level-error of the adjusted statistic is actually order n2.

Delayed wound healing and keloid formation following argon laser treatment or dermabrasion during isotretinoin treatment.

Abstract: We report the observation of delayed wound healing and keloid formation in three patients, following dermabrasion or Argon laser treatment administered while they were receiving isotretinoin for acne or rosacea.

Evidence for a large and flexible region of human serum albumin possessing high affinity binding sites for salicylate, warfarin, and other ligands.

Abstract: The relations between the single high affinity binding sites for azapropazone, phenylbutazone, chlorpropamide, sulfathiazole, and iophenoxate and the binding regions of human serum albumin represented by the marker ligands diazepam, phenol red, salicylate, and warfarin were examined by a series of competition experiments. Binding was determined by equilibrium dialysis at pH 7.0. In order to ensure an accurate analysis of the competition experiment, the number of moles of ligand bound per mole of protein was usually 0.4 or less to minimize ligand binding to weaker sites. Furthermore, binding of both ligands was determined in all experiments (except for iophenozate). None of the test ligands competed with diazepam for a common high affinity binding site, but, surprisingly, they were all able to displace two or three of the other marker ligands according to a competitive scheme. These findings show, first, the existence of a particular serum albumin region for high affinity binding of diazepam. Secondly, they imply that it is not necessary to assume the existence of new drug binding regions beyond those existing for phenol red, salicylate, and warfarin. On the contrary, the relatively many examples of competitive binding indicate that the binding regions represented by the last-mentioned three marker ligands are placed quite close to each other in the albumin molecule in a common region, which is suggested to be located at subdomains 1C and 2A-B. The region must be relatively large, because in some cases independent high affinity binding of pairs of ligands is observed. It is probably also rather flexible, inasmuch as no clear relation could be found between the chemical structure of the test ligands and the two or three marker ligands with which they compete. Correlations between primary association constants and partition coefficients for both marker ligands and test ligands, in the unionized forms, between n-hexane or 1-octanol and aqueous media showed that hydrophobic forces are important for the binding processes. However, the data also showed that other attractive forces must be operative as well.

Localization in the self-interaction-corrected density-functional formalism.

Abstract: We show that the self-interaction-corrected (SIC) local spin-density (LSD) approximation can describe localization in a system where the Coulomb interaction is large compared with the band-width. In contrast with the normal LSD approximation, the SIC approximation can be used for a band with orbital degeneracy, even if the band is not half filled. The method is applied to the one-dimensional Hubbard model for which there is an exact solution. The total energy, the band gap, the local moment, and the momentum distribution are substantially better described than in the LSD approximation. For some of these properties the SIC approach is shown to compare favorably with the Gutzwiller ansatz.

Kidney tissue somatomedin C and initial renal growth in diabetic and uninephrectomized rats.

Abstract: Kidney growth after induction of experimental diabetes in rats was compared to compensatory renal growth in response to unilateral nephrectomy. After 4 days of diabetes, kidney weight had increased from 816 +/- 21 mg (SEM) to 940 +/- 42 mg (15%). In insulin-treated diabetic rats kidney weight was unchanged at the end of the study, namely 828 +/- 15 mg. In unilaterally nephrectomised rats kidney weight increased from 840 +/- 20 mg (SEM) to 1050 +/- 60 mg during 4 days (24%). We observed increased kidney content of somatomedin C in both diabetic and uninephrectomized rats. In untreated diabetic rats it was maximal after 48 h, with an increase of 77% (3469 +/- 312 ng/g (SEM) versus 1961 +/- 173 ng/g). After 4 days the somatomedin C content had returned to initial levels. In insulin-treated rats somatomedin C content did not increase during the observation period. The somatomedin C content of the remaining kidney after unilateral nephrectomy was maximal after 24 h with an increase of 58% (from 1340 +/- 203 ng/g (SEM) to 2122 +/- 214 ng/g). The somatomedin C content returned to normal at day 4. Serum somatomedin C declined insignificantly in diabetic animals during the experimental period, but a significant decrease (p less than 0.02) was found in uninephrectomized rats. This study demonstrates that kidney somatomedin C peaks during the first or second day after uninephrectomy or induction of diabetes, respectively, and that insulin treatment sufficient to prevent kidney growth abolishes the increase. These similar rapid initial hypertrophies/hyperplasies may thus be dependent on local somatomedin C formation.

Combined Oxygen and Nitrous Oxide Microsensor for Denitrification Studies

Abstract: The construction of a microsensor which can be used to measure O2 and N2O simultaneously is described The microsensor exhibited a linear response to both O2 and N2O, and the response to N2O was independent of the O2 concentration and vice versa The N2O detection limit of a microsensor with a tip diameter of 20 μm was around 1 μmol liter−1 The signals for O2 and N2O were affected by hydrogen sulfide, but other interfering agents were not observed in the biofilms and sediments analyzed Microprofiles of O2 and N2O were measured in a biofilm which was exposed to acetylene to block the N2O reductase activity of denitrifying bacteria O2 penetrated about 05 mm into the biofilm and was not affected by acetylene, but the N2O concentration at 14 mm depth increased from 32 to 411 μmol liter−1 after the addition of the inhibitor The shape of the N2O profile after the addition of acetylene showed that denitrification (denitrifying activity) was detectable in all anoxic layers of the biofilm

Solar oscillation frequencies and the equation of state

Abstract: Observed oscillation frequencies of the Sun can be used to investigate the properties of matter under conditions that cannot be achieved on Earth. In particular the frequencies are sensitive to the equation of state. A recently developed treatment of the partition functions leads to a substantial improvement in the agreement between the observed and the computed frequencies.

Modulation of plasma membrane H+-ATPase from oat roots by lysophosphatidylcholine, free fatty acids and phospholipase A2

Abstract: Plasma membrane vesicles were purified from 8-day-old oat (Avena sativa L. cv. Brighton) roots in an aqueous polymer two-phase system. The plasma membranes possessed high specific ATPase activity [ca 4 μmol P1 (mg protein)−1 min−1 at 37°C]. Addition of lysophosphatidylcholine (lyso-PC) produced a 2–3 fold activation of the plasma membrane ATPase, an effect due both to exposure of latent ATP binding sites and to a true activation of the enzyme. Lipid activation increased the affinity for ATP and caused a shift of the pH optimum of the H+ -ATPase activity to 6.75 as compared to pH 6.45 for the negative H+-ATPase. Activation was dependent on the chain length of the acyl group of the lyso-PC, with maximal activition obtained by palmitoyl lyso-PC. Free fatty acids also activated the membrane-bound H+-ATPase. This activation was also dependent on chain length and to the degree of unsaturation, with linolenic and arachidonic acid as the most efficient fatty acids. Exogenously added PC was hydrolyzed to lyso-PC and free fatty acids by an enzyme in the plasma membrane preparation, presumably of the phospholipase A type. Both lyso-PC and free fatty acids are products of phospholipase A2 (EC 3.1.1.4) action, and addition of phospholipase A2 from animal sources increased the H+-ATPase activity within seconds. Interaction with lipids and fatty acids could thus be part of the regulatory system for H+-ATPase activity in vivo, and the endogenous phospholipase may be involved in the regulation of the H+-ATPase activity in the plasma membranne.

Test of the isotropy of the speed of light using fast-beam laser spectroscopy.

Abstract: We report on a novel experiment sensitive to the anisotropy of the one-way speed of light. The frequency of a two-photon transition in a fast atomic beam is compared to the frequency of a stationary absorber while the direction of the fast beam is rotated relative to the fixed stars. The experiment yields an improved upper limit for the anisotropy: $\frac{\ensuremath{\Delta}c}{c}\ensuremath{\le}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$.

The stabilizing effect of the ligamentous structures in the sinus and canalis tarsi on movements in the hindfoot An experimental study

Abstract: Three-plane kinesiology of hindfoot instability was studied after lesions to the ligamentous structures in the sinus and canalis tarsi in 20 amputation specimens. Neither a lesion of the cervical ligament nor of the interosseous talocalcaneal ligament resulted in an increase in the total range of movements above 2.6 degrees in any of the three planes. However, the percentage increase in the total range of movements after cutting of the ligaments was generally largest in the talocalcaneal joint compared to the increase in the total hindfoot joint complex. The largest percentage increase (43%) in the talocalcaneal joint occurred at dorsiflexion after cutting the interosseous talocalcaneal ligament. The demonstrated minor instability after experimental lesions of the ligamentous structures in the sinus and canalis tarsi may have a clinical identity in the sinus tarsi syndrome. Patients with that syndrome rarely present an objective hindfoot instability, although a major complaint is a feeling of hindfoot instability.

Intracellular pH regulation in resting and contracting segments of rat mesenteric resistance vessels.

Abstract: 1. The pH-sensitive dye 2',7'-bis-(2-carboxyethyl)-5 (and -6)-carboxyfluorescein (BCECF) was used to measure intracellular pH (pHi) in segments of rat resistance vessels (internal diameter about 200 microns) with the vessels mounted in a myograph for simultaneous measurements of isometric contraction. 2. BCECF loaded slowly into the vessels over 1 h and did not affect the maximal contractility of the vessels. There was a loss of dye with time which, however, was very slow when the segments were only excited for 2 s/min, suggesting that the loss was mainly due to dye bleaching with only a very slow leak. 3. The ratio of the emissions (at 540 nm) with excitation at 495 and 450 nm was calibrated in terms of pH using the K+-H+ ionophore nigericin. This calibration gave a pHi value of 7.15 +/- 0.02 (n = 20), suggesting that hydrogen ions are not in electrochemical equilibrium in these vascular smooth muscles which have a membrane potential of about -60 mV. 4. Addition of 10 mM-NH4Cl caused a transient alkalinization and wash-out of 10 mM-NH4Cl a transient acidification. Increasing CO2 with maintained bicarbonate caused a rapid acidification followed by an incomplete recovery. Removal of CO2 and bicarbonate (HEPES-buffered solution) with constant extracellular pH caused a transient alkalinization but steady-state pHi was not significantly altered. 5. In bicarbonate-free buffer the Na+-H+ exchange blocker 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and sodium-free conditions caused a slow acidification. In bicarbonate buffer (PSS) EIPA had no detectable effect after 10 min but the anion exchange blocker diisothio-cyanatostilbenedisulphonic acid (DIDS) caused a small acidification over that time course. 6. The rate of recovery after an acid load was about 50% lower in HEPES buffer compared to PSS and it was inhibited by EIPA. In PSS amiloride and EIPA each had a small inhibitory effect on the pH recovery after an acid load. DIDS also inhibited the recovery from an acid load in PSS and this effect was additive to that of EIPA. DIDS and EIPA also had additive inhibitory effects on the 22Na+ influx stimulated by the acid loading, while in HEPES buffer DIDS had no effect on either pH recovery or 22Na+ influx. These results suggest that a Na+-H+ exchange and an influx of bicarbonate coupled to sodium influx are of importance for pHi control in these vessels.(ABSTRACT TRUNCATED AT 400 WORDS)