Showing papers by "University of Copenhagen published in 1995"

W/kit gene required for interstitial cells of Cajal and for intestinal pacemaker activity

Abstract: The pacemaker activity in the mammalian gut is responsible for generating anally propagating phasic contractions. The cellular basis for this intrinsic activity is unknown. The smooth muscle cells of the external muscle layers and the innervated cellular network of interstitial cells of Cajal, which is closely associated with the external muscle layers of the mammalian gut, have both been proposed to stimulate pacemaker activity. The interstitial cells of Cajal were identified in the last century but their developmental origin and function have remained unclear. Here we show that the interstitial cells of Cajal express the Kit receptor tyrosine kinase. Furthermore, mice with mutations in the dominant white spotting (W) locus, which have cellular defects in haematopoiesis, melanogenesis and gametogenesis as a result of mutations in the Kit gene, also lack the network of interstitial cells of Cajal associated with Auerbach's nerve plexus and intestinal pacemaker activity.

The elevational gradient of species richness: a uniform pattern?

Abstract: The decline in species richness with increasing elevation is widely accepted as a general pattern (Table 1). In as much as the elevational gradient is often claimed to mirror the latitudinal gradient, species richness is assumed to decrease monotonically (i.e. because of reduced temperature and consequent decrease in productivity). Perhaps because such a relation is intuitive, biologists have readily generalized the results of a few early studies of tropical birds as supporting a general biogeographic

Both Subcutaneously and Intravenously Administered Glucagon-Like Peptide I Are Rapidly Degraded From the NH2-Terminus in Type II Diabetic Patients and in Healthy Subjects

Abstract: To fate of exogenous glucagon-like peptide I (GLP-I)(7-36) amide was studied in nondiabetic and type II diabetic subjects using a combination of high-pressure liquid chromatography (HPLC), specific radioimmunoassays (RIAs), and a sensitive enzyme-linked immunosorbent assay (ELISA), whereby intact biologically active GLP-I and its metabolites could be determined. After GLP-I administration, the intact peptide could be measured using an NH2-terminally directed RIA or ELISA, while the difference in concentration between these assays and a COOH-terminal-specific RIA allowed determination of NH2-terminally truncated metabolites. Subcutaneous GLP-I was rapidly degraded in a time-dependent manner, forming a metabolite, which co-eluted on HPLC with GLP-I(9-36) amide and had the same immunoreactive profile. Thirty minutes after subcutaneous GLP-I administration to diabetic patients (n = 8), the metabolite accounted for 88.5 +/- 1.9% of the increase in plasma immunoreactivity determined by the COOH-terminal RIA, which was higher than the levels measured in healthy subjects (78.4 +/- 3.2%; n = 8; P < 0.05). Intravenously infused GLP-I was also extensively degraded, but no significant differences were seen between the two groups. Intact GLP-I accounted for only 19.9 +/- 3.4% of the increase in immunoreactivity measured with the COOH-terminal RIA in normal subjects (n = 8), and 25.0 +/- 4.8% of the increase in diabetic subjects (n = 8), the remainder being the NH2-terminally truncated metabolite.

Degradation of glucagon-like peptide-1 by human plasma in vitro yields an N-terminally truncated peptide that is a major endogenous metabolite in vivo

Abstract: The metabolism of glucagon-like peptide-1 (GLP-1) has not been studied in detail, but it is known to be rapidly cleared from the circulation. Measurement by RIA is hampered by the fact that most antisera are side-viewing or C-terminally directed, and recognize both intact GLP-1 and biologically inactive. N-terminally truncated fragments. Using high pressure liquid chromatography in combination with RIAs, methodology allowing specific determination of both intact GLP-1 and its metabolites was developed. Human plasma was shown to degrade GLP-1-(7-36)amide, forming an N-terminally truncated peptide with a t1/2 of 20.4 +/- 1.4 min at 37 C (n = 6). This was unaffected by EDTA or aprotinin. Inhibitors of dipeptidyl peptidase-IV or low temperature (4 C) completely prevented formation of the metabolite, which was confirmed to be GLP-1-(9-36)amide by mass spectrometry and sequence analysis. High pressure liquid chromatography revealed the concentration of GLP-1-(9-36)amide to be 53.5 +/- 13.7% of the concentration of endogenous intact GLP-1 in the fasted state, which increased to 130.8 +/- 10.0% (P < 0.01; n = 6) 1 h postprandially. Metabolism at the C-terminus was not observed. This study suggests that dipeptidyl peptidase-IV is the primary mechanism for GLP-1 degradation in human plasma in vitro and may have a role in inactivating the peptide in vivo.

Replantation of 400 avulsed permanent incisors. 4. Factors related to periodontal ligament healing.

Abstract: 400 avulsed and replanted permanent teeth were examined for periodontal ligament (PDL) healing, using standardized radiographic and clinical examination procedures (i.e. percussion test and mobility test). The effect of various clinical factors was examined, such as age and sex of the patient, type of tooth replanted, presence of crown fracture or bone fracture, stage of root development (including apical diameter and length of the pulp), type and length of extra-alveolar storage, clinical contamination of the root surface, type of root surface cleansing procedure, type and length of splinting period and antibiotic therapy. Surface resorption was generally diagnosed after 12 months; while inflammatory resorption and replacement resorption (ankylosis) were usually observed after 1 month and 1-2 months respectively. Most resorptive processes were diagnosed within the first 2-3 years. However, although rarely, even after 5 and 10 years new resorptive processes could be diagnosed. A univariate statistical analysis of 272 teeth revealed 9 factors significantly related to PDL healing. A subsequent multivariate analysis revealed that the following 4 factors had the strongest impact upon PDL healing, in descending order of significance: Stage of root development; length of the dry extra-alveolar storage period; immediate replantation and length of the wet period (saliva or saline storage). Nonphysiological storage, such as homemade saline and sterilizing solutions (chloramine and alcohol) always led to root resorption. Storage in tap water for more than 20 minutes usually led to root resorption. The common denominator for all these factors related to PDL healing appears to be survival of the PDL cells along the root surface. Based on these findings, immediate replantation is recommended irrespective of stage of root development.

A resolution of the lek paradox

Abstract: Sexual traits are usually more phenotypically variable than non-sexual traits. We show that additive genetic variation is also higher in sexual traits, and often greater than in the same, non-sexually selected trait in females or other comparable traits in the same species. In contrast there is no difference in residual variation (environmental and non-additive) or heritability. The higher genetic variability of sexual traits is contrary to the expectations of the lek paradox. This hypothesis predicts that strong sexual selection, due to female choice, leads to fixation of most genetic variation in male sexual characters. High genetic variability in sexual traits can be explained if they are subject to directional selection that is greater than linear because this selects for greater phenotypic variation. It favours modifiers that increase the number of genes and the average contribution of a locus to phenotypic variance in sexual traits. These results provide a general resolution of the lek paradox.

A genealogy of sovereignty

Abstract: The concept of sovereignty is central to international relations theory and theories of state formation, and provides the foundation of the conventional separation of modern politics into domestic and international spheres. In this book Jens Bartelson provides a critical analysis and conceptual history of sovereignty, dealing with this separation as reflected in philosophical and political texts during three periods: the Renaissance, the Classical Age, and Modernity. He argues that the concept of sovereignty and its place within political discourse are conditioned by philosophical and historiographical discontinuities between the periods, and that sovereignty should be regarded as a concept contingent upon, rather than fundamental to, political science and its history.

Enhanced quantitative resistance against fungal disease by combinatorial expression of different barley antifungal proteins in transgenic tobacco

Abstract: cDNAs encoding three proteins from barley (Hordeum vulgare), a class-II chitinase (CHI), a class-II beta-1,3-glucanase (GLU) and a Type-I ribosome-inactivating protein (RIP) were expressed in tobacco plants under the control of the CaMV 35S-promoter. High-level expression of the transferred genes was detected in the transgenic plants by Northern and Western blot analysis. The leader peptides in CHI and GLU led to accumulation of these proteins in the intercellular space of tobacco leaves. RIP, which is naturally deposited in the cytosol of barley endosperm cells, was expressed either in its original cytosolic form or fused to a plant secretion peptide (spRIP). Fungal infection assays revealed that expression of the individual genes in each case resulted in an increased protection against the soilborne fungal pathogen Rhizoctonia solani, which infects a range of plant species including tobacco. To create a situation similar to 'multi-gene' tolerance, which traditional breeding experience has shown to provide crops with a longer-lasting protection, several of these antifungal genes were combined and protection against fungal attack resulting from their co-expression in planta was evaluated. Transgenic tobacco lines were generated with tandemly arranged genes coding for RIP and CHI as well as GLU and CHI. The performance of tobacco plants co-expressing the barley transgenes GLU/CHI or CHI/RIP in a Rhizoctonia solani infection assay revealed significantly enhanced protection against fungal attack when compared with the protection levels obtained with corresponding isogenic lines expressing a single barley transgene to a similar level. The data indicate synergistic protective interaction of the co-expressed antifungal proteins in vivo.

Greenland palaeotemperatures derived from GRIP bore hole temperature and ice core isotope profiles

Abstract: Modelling the temperature profile along the GRIP deep bore at the summit of the Greenland ice sheet leads to conversion factors that allow interpretation of the dated stable isotope profile as a climatic temperature record spanning the last 113,000 years. When corrected for surface elevation changes, the late glacial to Boreal temperature shift appears to have been 22 °C in central Greenland. The warming at the end of the last glaciation probably began earlier in Greenland, than in Antarctica. DOI: 10.1034/j.1600-0889.47.issue5.9.x

Disease Activity Courses in a Regional Cohort of Crohn's Disease Patients

Abstract: Background: The study was a follow-up of an inception cohort of 373 patients with Crohn's disease.Methods: Annual assessments, life table analyses, and Markov chain analyses, estimating the probability for remission and relapse with time, and working capacity were carried out.Results: The clinical course of Crohn's disease differs markedly over time, from ever-relapsing cases to a quiescent course with remission for several years, interrupted by years with relapse. No predictive factors have been found for the subsequent course with regard to age, sex, extent of disease at diagnosis, and treatment in the year of diagnosis. The relapse rate within the year of diagnosis and the following 2 years, however, does correlate positively (p = 0.00001) with the relapse rate in the following 5 years. Furthermore, the relapse rate for 1 year during the disease course influences the relapse rate the following year, indicating a disease pattern over time with waves of at least 2 years' duration. A slight tendency towar...

Distribution of glp-1 binding sites in the rat brain : evidence that exendin-4 is a ligand of brain glp-1 binding sites

Abstract: The distribution and biochemical properties of glucagon-like peptide (GLP)-1(7-36) amide (GLP-1) binding sites in the rat brain were investigated. By receptor autoradiography of tissue sections, the highest densities of [125I]GLP-1 binding sites were identified in the lateral septum, the subfornical organ (SFO), the thalamus, the hypothalamus, the interpenduncular nucleus, the posterodorsal tegmental nucleus, the area postrema (AP), the inferior olive and the nucleus of the solitary tract (NTS). Binding studies with [125I][Tyr39] exendin-4, a GLP-1 receptor agonist, showed an identical distribution pattern of binding sites. Binding specificity and affinity was investigated using sections of the brainstem containing the NTS. Binding of [125I]GLP-1 to the NTS was inhibited concentration-dependently by unlabelled GLP-1 and [Tyr39]exendin-4 with KI values of 3.5 and 9.4 nM respectively. Cross-linking of hypothalamic membranes with [125I]GLP-1 or [125I][Tyr39]exendin-4 identified a single ligand-binding protein complex with a molecular mass of 63,000 Da. The fact that no GLP-1 binding sites were detected in the cortex but that they were detected in the phylogenetically oldest parts of the brain emphasizes that GLP-1 may be involved in the regulation of vital functions. In conclusion, the biochemical data support the idea that the central GLP-1 receptor resembles the peripheral GLP-1 receptor. Furthermore, the presence of GLP-1 binding sites in the circumventricular organs suggests that these may be receptors which act as the target for both peripheral blood-borne GLP-1 and GLP-1 in the nervous system.

Membrane mechanisms and intracellular signalling in cell volume regulation.

Abstract: Recent work on selected aspects of the cellular and molecular physiology of cell volume regulation is reviewed. First, the physiological significance of the regulation of cell volume is discussed. Membrane transporters involved in cell volume regulation are reviewed, including volume-sensitive K + and CI − , channels, K + , CI − and Na + , K + , 2CI − cotransporters, and the Na + , H + , CI − , HCO 3 − , and K + , H + exchangers. The role of amino acids, particularly taurine, as cellular osmolytes is discussed. Possible mechanisms by which cells sense their volumes, along with the sensors of these signals, are discussed. The signals are mechanical changes in the membrane and changes in macromolecular crowding. Sensors of these signals include stretch-activated channels, the cytoskeleton, and specific membrane or cytoplasmic enzymes. Mechanisms for transduction of the signal from sensors to transporters are reviewed. These include the Ca 2+ -calmodulin system, phospholipases, polyphosphoinositide metabolism, eicosanoid metabolism, and protein kinases and phosphatases. A detailed model is presented for the swelling-initiated signal transduction pathway in Ehrlich ascites tumor cells. Finally, the coordinated control of volume-regulatory transport processes and changes in the expression of organic osmolyte transporters with long-term adaptation to osmotic stress are reviewed briefly.

The PiGMaP consortium linkage map of the pig (Sus scrofa).

Abstract: A linkage map of the porcine genome has been developed by segregation analysis of 239 genetic markers. Eighty-one of these markers correspond to known genes. Linkage groups have been assigned to all 18 autosomes plus the X Chromosome (Chr). As 69 of the markers on the linkage map have also been mapped physically (by others), there is significant integration of linkage and physical map data. Six informative markers failed to show linkage to these maps. As in other species, the genetic map of the heterogametic sex (male) was significantly shorter (∼16.5 Morgans) than the genetic map of the homogametic sex (female) (∼21.5 Morgans). The sex-averaged genetic map of the pig was estimated to be ∼18 Morgans in length. Mapping information for 61 Type I loci (genes) enhances the contribution of the pig gene map to comparative gene mapping. Because the linkage map incorporates both highly polymorphic Type II loci, predominantly microsatellites, and Type I loci, it will be useful both for large experiments to map quantitative trait loci and for the subsequent isolation of trait genes following a comparative and candidate gene approach.

Prevalence and Sex-Ratio of the Subtypes of Migraine

Abstract: Background The aim of this study was to provide the prevalence and sex-ratio of subtypes of migraine diagnosed by neurological interview according to the criteria of the International Headache Society. Methods In all, 3000 males and 1000 females aged 40 years were randomly selected from the Danish population. They received a mailed questionnaire regarding migraine. The questionnaire response rate was 87%. People with self-reported migraine and a random sample of those reporting no migraine were invited to a headache interview, and a physical and a neurological examination. Those not reacting to the invitation were interviewed by telephone. Participation at the interview was 87%. Kappa was 0.77 validating self-reported migraine in the questionnaire against the diagnosis of the clinical interview. Results Lifetime prevalences of migraine without aura, migraine with aura, migraine aura without headache, and migrainous disorder were 8%, 4%, 1% and 1% in males and 16%, 7%, 3% and 2% in females. Overall lifetime prevalence of any type of migraine was 18%; 12% in males and 24% in females. This is lower than the sum of the prevalences since migraine diagnoses are not mutually exclusive. The male:female ratios of migraine without aura, migraine with aura, migraine aura without headache, and migrainous disorder were approximately 1:2. Conclusions Migraine is more prevalent than previously thought. There was a significant preponderance in females of all the subtypes of migraine except migrainous disorder.

Role of Neutrophils in Myocardial Ischemia and Reperfusion

Abstract: In the intact organism, ischemic myocardial injury initiates an acute inflammatory response in which polymorphonuclear leukocytes (PMNs) are major participants. Evidence indicates that the interplaying inflammatory reactions are augmented by reperfusion and that accumulating PMNs can contribute to myocardial damage, eg, by release of oxygen-derived free radicals, proteases, and leukotrienes. In experimental models, interventions aimed at PMN inhibition can exert cardioprotective effects, and some of these strategies raise hope for future clinical applications. A greater understanding of the mechanisms involved in PMN-mediated myocardial damage is necessary for designing a rational approach to reduce the putative detrimental effects of PMNs without antagonizing their favorable consequences in tissue healing.

Concentration and transport of nitrate by the mat-forming sulphur bacterium Thioploca

Abstract: MARINE species of Thioploca occur over 3,000 km along the continental shelf off Southern Peru and North and Central Chile1–4. These filamentous bacteria live in bundles surrounded by a common sheath and form thick mats on the sea floor under the oxygen-minimum zone in the upwelling region, at between 40 and 280 m water depth. The metabolism of this marine bacterium5,6 remained a mystery until long after its discovery1,7. We report here that Thioploca cells are able to concentrate nitrate to up to 500 mM in a liquid vacuole that occupies >80% of the cell volume. Gliding filaments transport this nitrate 5–10 cm down into the sediment and reduce it, with concomitant oxidation of hydrogen sulphide, thereby coupling the nitrogen and sulphur cycles in the sediment.

Spectroscopy for E and S0 galaxies in nine clusters

Abstract: Central velocity dispersions, Mg-2 line indices and radial velocities for 220 E and SO galaxies are derived on the basis of intermediate resolution spectroscopy Galaxies in the following clusters have been observed: Abell 194, Abell 539, Abell 3381, Abell 3574, S639, S753, Doradus, HydraI (Abell 1060) and Grm 15 For 151 of the galaxies, the velocity dispersion has not previously been measured 134 of the Mg-2 determinations are for galaxies with no previous measurement The spectra cover either 500 or 1000 Angstrom, centred on the magnesium triplet at 5177 Angstrom The observations were obtained with the Boiler & Chivens spectrograph at the ESO 15-m telescope and with OPTOPUS, a multi-object fibre-fed B&C spectrograph, at the ESO 36-m telescope The data are part of our ongoing study of the large-scale motions in the Universe and the physical background for the Fundamental Plane The Fourier fitting method was used to derive the velocity dispersions and radial velocities The velocity dispersions have been corrected for the effect of the size of the aperture The correction was established on the basis of velocity dispersion profiles available in the literature A comparison with results from Davies et al shows that the derived central velocity dispersions have an rms error of 0036 in log sigma There is no offset relative to the velocity dispersions from Davies et al The offset relative to data from Lucey & Carter is - 0017 +/- 0011 in log sigma, with our velocity dispersions being the smallest The velocity dispersions derived from the B&C and the OPTOPUS observations, as well as the velocity dispersions published by Davies et al, Dressier, Lucey & Carter and Lucey et al, can be brought on a system consistent within 3 per cent The Mg-2 line indices have been corrected for the size of the apertures, transformed to the Lick system, and corrected for the effect of the velocity dispersion From comparison with data from Davies et al and from Faber, we find that the rms error of Mg-2 is 0013 Comparisons of the radial velocities with data from the literature show that our determinations are accurate to within approximate to 35 km s(-1) The accuracies reached for these observations are adequate for the study of the large-scale motions in the Universe and for investigations of the Fundamental Plane

Increased familial risk and evidence of genetic factor in migraine.

Abstract: Objective: To investigate familial occurrence of migraine with and without aura. Design: Familial occurrence of migraine with and without aura among first degree relatives and spouses of probands with migraine with or without aura and those who had never had migraine. All interviews of first degree relatives and spouses were done blindly by a neurological resident. The operational diagnostic criteria of the International Headache Society were used. Setting: population from Copenhagen County. Subjects: The 378 probands had 1109 first degree relatives and 229 spouses. Main outcome measures: Patterns of familial aggregation of migraine with and without aura as assessed by calculation of the population relative risk. Results: Compared with the general population the first degree relatives of probands with migraine without aura had 1.9 times the risk of migraine without aura and 1.4 times the risk of migraine with aura. The first degree relatives of probands with migraine with aura had nearly four times the risk of migraine with aura and no increased risk of migraine without aura. The first degree relatives of probands who had never had migraine had no increased risk of migraine either with or without aura. Spouses of probands with migraine without aura had 1.4 times the risk of migraine without aura whereas spouses of probands with migraine with aura had no increased risk of migraine with aura. Conclusion: The different familial patterns indicate that migraine without aura and migraine with aura have a different aetiology. Migraine without aura seems to be caused by a combination of genetic and environmental factors whereas migraine with aura is probably determined largely or exclusively by genetic factors.

Replantation of 400 avulsed permanent incisors. 2. Factors related to pulpal healing.

Abstract: Four hundred avulsed and replanted permanent teeth were examined for pulpal healing. In 110 teeth, the apical foramen was either open or half-open. In 16 teeth, the pulps were extirpated prophylactically. Thus, pulpal revascularization was considered possible in 94 teeth. Revascularization occurred in 32 teeth (34%). Pulp necrosis could usually be demonstrated after 3 weeks. Positive pulpal sensibility and radiographis signs of pulp canal obliteration were usually observed after 6 months. The effect of various clinical factors was examined, such as sex, age, type of tooth replanted, stage of root formation, type and length of extra-alveolar storage, clinical contamination of the root surface, type of cleansing procedure of the root surface, type and length of splinting and the use of antibiotics. Finally, the width of the apical foramen and the length of the root canal were measured on radiographs taken at the time of injury. A multivariate statistical analysis revealed that pulpal revascularization was more frequent in teeth with shorter distances from the apical foramen to the pulp horns. Furthermore, that wet storage (saliva and/or saline) for more than 5 min decreased the chance of pulpal revascularization; whereas dry extraalveolar storage had a monotonous effect on pulpal revascularization, i.e. decreasing chance of revasculatization with increasing length of the extraalveolar dry storage. Based on these findings, immediate replantation after brief cleansing in either tap water or saline is recommended.

At home in the world

Abstract: Ours is a century of uprootedness, with fewer and fewer people living out their lives where they are born. At such a time, in such a world, what does it mean to be "at home?" Perhaps among a nomadic people, for whom dwelling is not synonymous with being housed and settled, the search for an answer to this question might lead to a new way of thinking about home and homelessness, exile and belonging. At Home in the World is the story of just such a search. Intermittently over a period of three years Michael Jackson lived, worked, and traveled extensively in Central Australia. This book chronicles his experience among the Warlpiri of the Tanami Desert. Something of a nomad himself, having lived in New Zealand, Sierra Leone, England, France, Australia, and the United States, Jackson is deft at capturing the ambiguities of home as a lived experience among the Warlpiri. Blending narrative ethnography, empirical research, philosophy, and poetry, he focuses on the existential meaning of being at home in the world. Here home becomes a metaphor for the intimate relationship between the part of the world a person calls "self" and the part of the world called "other." To speak of "at-homeness," Jackson suggests, implies that people everywhere try to strike a balance between closure and openness, between acting and being acted upon, between acquiescing in the given and choosing their own fate. His book is an exhilarating journey into this existential struggle, responsive at every turn to the political questions of equity and justice that such a struggle entails. A moving depiction of an aboriginal culture at once at home and in exile, and a personal meditation on the practice of ethnography and the meaning of home in our increasingly rootless age, At Home in the World is a timely reflection on how, in defining home, we continue to define ourselves.

Performance of the ALEPH detector at LEP

Abstract: The performance of the ALEPH detector at the LEP e+e− collider is reviewed. The accuracy of the tracking detectors to measure the impact parameter and momentum of charged tracks is specified. Calorimeters are used to measure photons and neutral hadrons, and the accuracy obtained in energy and angle is given. An essential property of the detector is its ability to identify particles; the performance in identification of electrons, muons, neutrinos (from missing energy), charged hadrons, π0's and V0's is described.

Algebraic index theorem

Abstract: We prove the Atiyah-Singer index theorem where the algebra of pseudodifferential operators is replaced by an arbitrary deformation quantization of the algebra of functions on a symplectic manifold.

Star trackers for attitude determination

Abstract: One problem comes to all spacecrafts using vector information. That is the problem of determining the attitude. This paper describes how the area of attitude determination instruments has evolved from simple pointing devices into the latest technology, which determines the attitude by utilizing a CCD camera and a powerful microcomputer. The instruments are called star trackers and they are capable of determining the attitude with an accuracy better than 1 arcsecond. The concept of the star tracker is explained. The obtainable accuracy is calculated, the numbers of stars to be included in the star catalogue are discussed and the acquisition of the initial attitude is explained. Finally the commercial market for star trackers is discussed. >