Showing papers by "University of Copenhagen published in 1983"

Skeletal Muscle Adaptability: Significance for Metabolism and Performance

Abstract: The sections in this article are: 1 Motor Unit 1.1 Fibers per Motor Unit 1.2 Contractile Properties 1.3 Biochemical Basis for Differences in Twitch Properties 1.4 Histochemical Differentiation of Muscle Fibers 1.5 Ultrastructural Basis for Skeletal Muscle Fiber Typing 1.6 Maximal Contractile Force 1.7 Speed of Contraction 1.8 Fatigue Characteristics 1.9 Metabolic Characteristics 1.10 Ionic Composition of Skeletal Muscle 1.11 Summary 2 Muscle Fiber Composition in Human Skeletal Muscle 3 Motor-Unit Recruitment 4 Adaptive Response in Skeletal Muscle 4.1 Muscle Size 4.2 Metabolic Capacity 5 Connective Tissue 6 Capillaries 6.1 Methodology 6.2 Anatomy 6.3 Capillary Density 6.4 Capillary Length and Diameter 6.5 Use and Disuse 6.6 Regulation 7 Significance of Adaptation 7.1 Muscular Size 7.2 Substrate Stores 7.3 Enzyme Activities 7.4 Summary

Damping of nuclear excitations

Abstract: The authors review the theory and the empirical evidence of damping of simple nuclear excitations. The excitations considered are the particle states and vibrational states. The particle damping phenomena include the fragmentation of single-particle levels, the systematics of neutron strength functions, and the optical absorption of elastic scattering. Information on the known collective vibrational states is summarized and compared with theory. A theoretical model that has found considerable success is based on a damping mechanism in which the simple excitations mix with the surface vibrations. This implies that the surface damping dominates for excitation energies below about 15 MeV. There is a close relation between the single-particle damping and the damping of collective vibrations. However, the vibrational damping is strongly suppressed by the coherence between the particle and the hole. While the model reproduces many of the observed features of the data rather well, it tends to underpredict the spreading width by as much as a factor of 2. Thus other degrees of freedom, not well understood at present, may play a role in the damping.

General aspects of angiosperm evolution and macrosystematics

Abstract: Taxonomy makes increasing use of significant results from many fields of research including the rapidly developing fields of micro– and macromolecular chemistry, ultrastructure and micromorphology in combination with macromorphology, anatomy, embryology, cytology, paleontology, biological interaction and distribution. Some of these results have contributed to make the current systems of classifications more concordant. Recent studies on Cretaceous fossils are related to present–day angiosperms and their floral types. It is concluded that pleiomerous flowers with helically arranged parts (corresponding to the Magnolia type, though probably less elaborate), on the basis of recent evidence can still be regarded as the probably earliest floral type in angiosperms. But the trimerous flowers must also have appeared very early, at least in the Albian. There is also evidence that the monocotyledons had differentiated as a separate group at that time. Similarities between certain extant monocotyledons and certain dicotyledons, in particular between some Dios–coreales and some Annonales–Aristolochiales, indicate that the monocotyledons had their roots in early Cretaceous pro–Magnoliiflorae. Fossil petaliferous flowers from Cenomanian layers, and later of a variety of flower types, such as the obdiplostemo–nous, petaliferous, epigynous Scandianthus (similar to extant saxifragaceous genera), or flowers with secondarily pleiomerous androecia of the theaceous type are discussed in relation to the distribution of corresponding floral types in extant dicotyledons. The main features of the author's classification of angiosperms are outlined with notes on important, though often neglected, aspects and critical problems. Finally, an updated table of classification down to family rank is presented.

Pyruvate Carboxylase Activity in Primary Cultures of Astrocytes and Neurons

Abstract: The activity of the pyruvate carboxylase was determined in brains of newborn and adult mice as well as primary cultures of astrocytes, of cerebral cortex neurons, and of cerebellar granule cells. The activity was found to be 0.25 +/- 0.14, 1.24 +/- 0.07, and 1.75 +/- 0.13 nmol X min -1 X mg -1 protein in, respectively, neonatal brain, adult brain, and astrocytes. Neither of the two types of neurons showed any detectable enzyme activity (i.e., less than 0.05 nmol X min -1 X mg -1). It is therefore concluded that pyruvate carboxylase is an astrocytic enzyme.

Skeletal muscle tension, flow, pressure, and EMG during sustained isometric contractions in humans.

Abstract: In five healthy males sustained isometric torques during elbow flexion, knee extension, and plantar flexion correlated positively with intramuscular tissue pressure (MTP) in the range 0–80% of the maximal voluntary contraction (MVC). During passive compression of the muscle at rest 133-Xenon muscle clearance stopped when MTP reached diastolic arterial pressure (DAP) indicating that the muscle vascular bed was occluded. However, during sustained contractions this relation between DAP, flow and MTP was not seen. In two cases 133-Xenon clearance from M. soleus did not stop in spite of an 80% maximal contraction and MTP stayed below DAP. In other cases MTP would reach as high as 240 mm Hg before clearance was zero. In the deeper parts of the muscles MTP during contraction was increased in relation to the more superficial parts. The mean values for the %MVC that would stop MBF varied between 50 and 64% MVC for the investigated muscles. Mean rectified EMG (MEMG) showed a high correlation to MTP during sustained exhaustive contractions: When MEMG was kept constant MTP also remained constant while the exerted force decreased; when force was kept constant both MEMG and MTP increased in parallel. This demonstrated that muscle tissue compliance is decreasing during fatigue. Muscle ischemia occuring during sustained isometric contractions is partly due to the developed MTP, where especially the MTP around the veins in the deeper parts of the muscle can be considered of importance. However, ischemia is also affected by muscle fiber texture and anatomical distorsion of tissues.

Pregnancy in Ulcerative Colitis

Abstract: The course of pregnancy in 97 women with ulcerative colitis was studied over a 12-year period. During this period they had 173 pregnancies and delivered 136 children. There were two gemellary deliveries. Nine women had a spontaneous and 16 an induced abortion, of which 4 were performed on therapeutic indication. For a woman with ulcerative colitis the risk of an exacerbation of the bowel disease was 32% per year in her fertile years, whereas it was 34% per year during pregnancy. This difference is not statistically significant. As compared with women with an inactive bowel disease, women in whom the disease was active at the start of pregnancy had a small but significantly greater risk of spontaneous abortion and premature delivery. The frequency of malformations, prematurity, and neonatal hyperbilirubinaemia was not higher in the children of ulcerative colitis mothers than in those of healthy mothers. Treatment with sulphasalazine, salazosulphadimidine, and corticosteroids had no influence on the course and outcome of pregnancy. Birth length and weight of the children of mothers with ulcerative colitis equalled those for children of healthy mothers. In conclusion, pregnancy does not necessitate any change in the usual medical treatment of ulcerative colitis. Women with ulcerative colitis should be advised preferably to conceive at a time when their bowel disease is inactive. Generally, ulcerative colitis constitutes no indication for induced abortion.

Late Glacial Climate History from Ice Cores

Abstract: Ice cores contain information on climatic variations and their causes. Recent results obtained on the new deep ice core drilled in 1981 at Dye 3, South Greenland, in the frame of the US-Danish-Swiss Greenland Ice Sheet Program are: Comparison of the δ 180 variations in the Greenland ice cores with those in European lake carbonate exhibits strong similarities and provides time marks (13,000, 11,000, 10,000 B.P.) for the Late-Glacial section of the ice cores; CO2 concentration measurements in the occluded air indicate low (180–200 ppm) CO2 concentrations 30,000 to 15,000 B.P. and an increase to ca. 300 ppm around 13,000 B.P.,. The CO2 increase might reflect a change in the ocean circulation at the end of the last glaciation and could have contributed to the establishment of the Holocene environmental conditions; 10Be concentration measurements on samples covering the last 50,000 yaers show a correlation with δ 180, low δ 180 values corresponding to high 10Be concentrations (atoms per g of ice). Probably this mainly reflects changes in the rate of precipitation in the northern hemisphere.

Vesicular‐arbuscular mycorrhiza in field‐grown crops

Abstract: SUMMARY Development of infection by vesicular-arbuscular mycorrhiza (VAM) was studied in some field-grown crops. An infection plateau was reached within the first month after seedling emergence of spring barley, oats and peas. During the rest of the growth period the proportion of root length infected by VAM remained at about 50% in the cereals and 75% in the peas. In the spring, infection levels were low in winter wheat, winter rye and winter barley, and development of infection was slower in them than in the spring-sown crops. VAM infection was also studied in relation to soil depth and root density. The proportion of root length infected decreased markedly below 40 cm soil depth. Root density varied greatly between crops, whereas the absolute length of infected roots was similar in all crops. This indicates that susceptibility to infection was independent of host species. The results are discussed in relation to final phosphorus uptake and dry-matter production, and it is proposed that a relatively low soil-phosphorus availability was counterbalanced, to some extent, by a well-developed VAM infection.

Diabetic nephropathy and arterial hypertension

Abstract: The relationship between arterial blood pressure and diabetic nephropathy was examined in 61 Type 1 (insulin-dependent) diabetic patients (22 females and 39 males). All patients fulfilled the following criteria: persistent proteinuria (>0.5g/day), onset of diabetes before 31 years of age, age <42 years, serum creatinine <130 μmol/l, and no antihypertensive treatment. Thirty Type 1 diabetic patients without persistent proteinuria but matched for sex, age, ideal body weight and duration of diabetes, and 30 healthy subjects matched for sex, age and ideal body weight were also studied as controls. The diabetic patients with persistent proteinuria had elevated blood pressures (146/96±17/10 mmHg, mean±SD) compared with 123/75±11/8 mmHg in diabetic patients without persistent proteinuria, and normal subjects (120/77±6/6 mmHg; p<0.001 for each). Diastolic blood pressure ⩾95 mmHg was found in 51% of the group with persistent proteinuria. Elevated arterial blood pressure is frequently present in young Type 1 diabetic patients with diabetic nephropathy and normal serum creatinine.

Barley α-amylase/subtilisin inhibitor. I. Isolation and characterization

Abstract: A protein inhibitor of endogenous α-amylase 2 has been isolated from germinated barley by glycogen precipitation followed by cation-exchange chromatography. Preliminary kinetic analysis showed a mixed type mechanism of inhibition with an apparent Ki of 4×10−8M. The inhibitor formed well-defined complexes with barley malt α-amylase 2 and co-purified with the α-amylase by cycloheptaamylose affinity chromatography of glycogen precipitates. The inhibitor was inactive towards α-amylases from sorghum malt, hog pancreas, Aspergillus oryzae, and Bacillus subtilis. The amino acid composition and molecular weight near 21,000 were found to be the same as those of both “band-2 protein” previously identified in preparations of barley malt α-amylase and a specific subtilisin inhibitor from barley. Inhibition experiments confirmed that the malt α-amylase inhibitor is a strong inhibitor of subtilisin Carlsberg. Measurements of α-amylase activity in the presence of equimolar amounts of inhibitor and subtilisin showed that the inhibitor is “double headed”. The inhibitory activity towards α-amylase was lost after treatment of the inhibitor at 70 °C for 15 min. Isoelectric focusing patterns confirmed that the partially heat-labile, basic α-amylase isozymes (pI=6.6) of barley malt are complexes of α-amylase 2 (pI=6.2) and the inhibitor (pI=7.2). Evidence is presented to suggest that proteins with properties similar to those of the barley inhibitor are present in other cereals including wheat and rye. Possible in vivo functions and some practical aspects of the barley inhibitor are discussed.

Asthma and allergic rhinitis in the same patients.

Abstract: This study from Danish general practice gives figures about the simultaneous prevalence of asthma and allergic rhinitis and the order of onset among 7662 patients, who during 1 year consulted for one or both of these diseases. Twenty-eight percent of patients with asthma consulted because they also had allergic rhinitis, and 17% of patients with allergic rhinitis consulted because they also had asthma. Age- and sex-distributions are presented. In 25% of patients with both diseases the onset of both diseases occurred within the same year, while in 35% the onset of asthma occurred first and in 40% allergic rhinitis. Among patients with both diseases, who did not have onset of both within the same year, more than 75% of them had onset of one disease within 2 years of the other.

Characterization of uptake and release processes for D- and L-aspartate in primary cultures of astrocytes and cerebellar granule cells.

Abstract: The uptake ofl-andd-aspartate was studied in astrocytes cultured from prefrontal cortex and in granule cells cultured from cerebellum. A high affinity uptake system forl- andd-aspartate was found in both cell types, and the two stereoisomers exhibited essentially the sameK m - andV max -values in bouth astrocytes (l-aspartate:K m 77 μM;V max 11.8 nmol×min−1×mg−1;d-aspartate:K m 83 μM;V max 14.0 nmol×min−1×mg−1) and granule cells (l-aspartate:K m 32 μM;V max 2.8 nmol ×min−1×mg−1;d-aspartate:K m 26 μM;V max 3.0 nmol×min−1×mg−1). To investigate whetherl-glutamate,l-aspartate andd-aspartate use the same uptake system a detailed kenetic analysis was performed. The uptake kinetics of each one of the three amino acids was studied in the presence of the two other amino acids, and no essential differences between the uptake characteristics of the amino acids were found. In addition to the uptake studies the release ofD-aspartate from cerebellar granule cells was investigated and compared withl-glutamate release. A Ca2+-dependent, K+-induced release was found for both amino acids.

Immunization, Isolation of Immunoglobulins and Antibody Titre Determination

Abstract: During the past 10 years we have studied the immunization of several thousand outbred rabbits with a multitude of immunogens and analysed the resulting antisera. It is obvious that an immunization procedure that is optimal in all situations and guarantees a good antibody response in every animal does not exist. The aim of this chapter is to mention some of the factors that influence the antibody response and to describe an immunization scheme that has a statistically fair chance of giving good antisera. We also describe a simple procedure for the isolation of the immunoglobulin fraction of rabbit antiserum and compare some methods for antibody titre determination and determination of antibody specificity. Throughout the chapter the emphasis is on precipitating antisera to macromolecular antigens.

The physiology of rowing

Abstract: Rowing competitions for males are performed over a distance of 2000 m and last 5.8–7.4 min. This time is being improved by 0.01 min per year. Races are most often carried out with an initial spurt in order to increase the total aerobic metabolism. Large individuals have an advantage partly because of a larger anaerobic metabolism, but also because the almost constant weight of the boat, oars and coxswain becomes relatively less for oarsmen with larger body dimensions. Oxygen uptake during rowing increases with velocity to the power 2.4. It is estimated that the metabolic cost of rowing at racing speed corresponds to 6.41 O2 min‐1. The most successful oarsmen have a weight of 93 ± 2.6 kg (± s.e.) and a maximal oxygen uptake of 5.9 ± 0.08 1 min‐1 (± s.e.). A direct relationship is demonstrated between the average maximal oxygen uptake of the crew (y) and their placing (x) in an international regatta, y=6.15–0.08x (r=0.87). In contrast, measures of muscle strength do not separate the good from less ...

Diminished immunoreactive gastric inhibitory polypeptide response to a meal in newly diagnosed type I (insulin-dependent) diabetics.

Abstract: The release of immunoreactive gastric inhibitory polypeptide (IR-GIP) in response to a standard meal was examined in 10 normal subjects and 15 type I (insulin-dependent) diabetics 7 days (test I), 14 days (test II), and 3 months (test III) after time of diagnosis. During all three tests, the diabetics had significantly lower plasma IR-GIP concentrations than the controls from 15–90 min after the standard meal. The IR-GIP response in the diabetics measured as the integrated area under the response curve corresponded to 70% of that of normal subjects. β-cell function evaluated from the C-peptide response to the meal increased significantly from test I to test III whereas the IR-GIP response was similar during all three tests.As GIP is known to potentiate glucose-induced insulin secretion and possibly the biosynthesis of insulin, the low IR-GIP responses in subjects with type I diabetes may significantly influence insulin levels and hyperglycemia. (J Clin Endocrinol Metab 56:1306, 1983)

Effect of wind scouring on climatic records from ice-core oxygen-isotope profiles

Abstract: Removal of winter snow by wind explains why the annual mean oxygen-isotope ratio at an ice divide is 2.5‰ less negative than it is 1.2 km downslope. Cores from two sites on an ice cap, Ellesmere Island, Canada, show past variations in the difference, depending on where the ice originated relative to the scoured zone. Some ice-core climatic records may need correction for scouring.

Isolation and immunochemical characterization of the major allergen of birch pollen (Betula verrucosa)

Abstract: The classification of some of the extractable birch pollen antigens as allergens was established by crossed radioimmunoelectrophoresis (CRIE). In CRIE the major allergen (antigen 23) exhibited the strongest "radiostaining," and only a few other components of birch pollen extract were visibly radiostained. The major allergen and a preparation containing mainly the minor allergens, antigens 25 and 19, were isolated from a crude aqueous birch pollen extract by a combination of anion-exchange, size-exclusion, and chelate chromatography. Antigen 23 was purified to near homogeneity. The molecular weights and the pIs of antigens 23, 25, and 19 were determined to be 17,000 daltons, pI 5.25 (5.5, 5.0); 25,000 daltons, pI 5.0 (4.9, 5.4); and 29,000 daltons, pI 6.2 (5.4), respectively. The classification of antigen 23 as the major allergen in birch pollen was supported by results of RAST inhibition experiments, RAST screening, and skin prick testing.

Receptor binding of lactoferrin by human monocytes

Abstract: The binding of iron-saturated 125I-lactoferrin to human monocytes was studied at pH 7.4 and 37 degrees C. Monocytes in suspension bound 125I-lactoferrin by a reversible, saturable and specific binding indicating the presence of a receptor. The dissociation constant (KD) of the binding was estimated at about 4.5 x 10(-9) M and the number of receptors was about 1.6 x 10(6) per monocyte. The affinity of native lactoferrin (20% iron saturated) was only slightly below that of iron-saturated lactoferrin (KD about 7.9 x 10(-9) M). Human transferrin, horse cytochrome c and human immunoglobulin G were without inhibitory effect on the binding of 125I-lactoferrin. The majority of cell-bound 125I-lactoferrin was dissociable. The dissociation rate was not affected by addition of unlabelled lactoferrin to the dissociation medium. The binding of 125I-lactoferrin to adherent mononuclear blood cells showed an about 100-fold lower affinity (KD about 2.5 x 10(-7) M) than to cells in suspension, but the specificity of the binding was the same. These results are compatible with the idea that lactoferrin exerts a biological effect mediated by an interaction with cells of the monocyte/macrophage lineage.

Collapsibility and response variables in contingency tables

Abstract: SUMMARY Various definitions of the collapsibility of a hierarchical log linear model for a multidimensional contingency table are considered and shown to be equivalent. Necessary and sufficient conditions for collapsibility are found in terms of the generating class. It is shown that log linear models are appropriate for tables with response and explanatory variables if and only if they are collapsible onto the explanatory variables. Some key word8: Collapsibility; Contingency table; Graphical model; Interaction graph; Log linear model; Response variable; S-sufficiency. shown to be closely related. Some models have the property that relations between a set of the classifying factors may be studied by examination of the table of marginal totals formed by summing over the remaining factors. Such models are said to be collapsible onto the given set of factors. Collapsibility has important consequences for hypothesis testing and model selection, and can be useful in data reduction. We consider various definitions of collapsibility and show their equivalence. Furthermore, necessary and sufficient conditions for collapsi- bility are found in terms of the generating class. Many tables analysed in practice involve response variables. Simple examples, one of which is given in ? 3, suffice to show the importance of distinguishing between response and explanatory variables: first, that inappropriate models may be avoided, and second that natural and relevant models that are not log linear may be considered. This paper characterizes appropriate and inappropriate log linear models for tables with response variables and some alternative approaches for the analysis of such tables are briefly considered. We consider a multidimensional contingency table N based on a set of classifying factors F. For a given subset a of F we are interested in the table of marginal totals Na, that is to say the table of cell counts summed over the remaining factors aC, that is the complement of a in F. We identify a hierarchical log linear model L, that is the set of probabilities p E L, with its generating class, whose elements, generators, are given in square brackets: thus for example the model (AB) (BCD) for a 4-way table corresponds