Showing papers by "University of Copenhagen published in 1970"

Contraction Times and Fibre Types in Intact Human Muscle

Abstract: Twitches were recorded in situ in muscles of normal humans by small transducers connected to a needle in the tendon. The twitches were elicited by stimuli in the endplate zone, the force of the smallest twitches corresponding to the average of one or two motor units. The time to peak contraction was measured of 20–30 bundles of fibres in each muscle examined. The histograms of contraction times agreed with histochemical findings; contraction times longer than 60 msec corresponded to the proportion of fibres rich in mitochondria. Thus, long contraction times predominated in the soleus and gastrocnemius muscles, comprised half the times in the anterior tibia], a third in the brachial biceps (long head) and a few per cent in the brachial triceps muscle (lateral head). Bundles of fibres with short contraction times, those poor in mitochondria had a higher temperature coefficient of the time to peak than bundles with long contraction times. During hypoxia the contraction times shortened. The contraction time of motor units first activated voluntarily lay near the mean of bundles activated electrically. The contraction times of fasciculating fibres were in the range of electrically evoked twitches; the force was about three times that of voluntarily activated units.

Copper ions as poison in the sea and in freshwater

Abstract: Copper in ionic form is found to be very poisonous for photosynthesis and growth of unicellular algae at concentrations of Cu usually found in natural waters. This indicates that Cu is ordinarily not present in ionic form but is complexed by organic matter such as polypeptides. The affinity of Cu to diethyl-dithiocarbaminate is very much higher than to the organic matter which complexes Cu in nature. Thus, it is not possible to distinguish the two forms of Cu during analysis. Complexed Cu is not poisonous to algae. It has recently been shown that ocean water in the centres of upwelling becomes suitable for plankton growth only after the addition of a chelator. This suggests that a large part of the Cu found in the subsurface waters of the oceans is present in ionic form. Some manufactures of C14 ampoules have used ordinary distilled water which often has a content of about 250 μg Cu/l. Thus, it is very likely that some productivity measurements have been influenced. A likely example is mentioned.

Structural and functional aspects of salivary fluid section in Calliphora

Abstract: Calliphora salivary glands are described, emphasizing correlations between structure and physiology. In vitro studies show that the distal part of each gland produces a potassium-rich primary saliva when stimulated with 5-hydroxytryptamine or cyclic AMP. The secretory cells have elaborate canaliculi opening into the lumen. Stimulation of the secretory region causes a 60-fold increase in fluid secretion rate without affecting cell structure. The proximal part of the gland reabsorbs potassium when stimulated with cyclic AMP, but 5-HT has no effect. Potassium reabsorption from the primary saliva results in formation of a dilute saliva. The structure of the secretory and reabsorptive cells is discussed with regard to the functional role of long narrow channels in transport.

Monomers and Dimers

Abstract: We prove that the free energy of an arbitrary monomer-dimer system is analytic in the density and temperature for nonzero density, and hence that the system has no phase transition. This result can also be used to locate the z =e 2sh roots of the Heisenberg ferromagnet or antiferromagnet at high temperature.

An erupted migmatite from Cerro del Hoyazo, SE Spain

Abstract: The almandine-bearing biotite-cordierite-labradorite dacite of the Cerro del Hoyazo is part of the Neogene volcanic range in SE Spain, extending roughly from Cabo de Gata to Cartagena.

Malignant melanomas of the human uvea

Abstract: All cases (302) of malignant intraocular melanomas in Denmark between 1943–1952 were followed up and evaluated 25 years after enucleation, which was the treatment used immediately after diagnosis during that period. The follow-up percentage was 99, 82% of the total being dead at the time of follow-up, bringing the real course of the malignant uveal melanoma in a traditionally treated series nearer to the truth. The same series was analysed in 1963 and 1970. Three-quarters of the patients were hospitalized immediately before and/or in the process of dying. In the series of choroidal and/or ciliary body melanoma the autopsy frequency was 36. Death with metastases took place in 51% (150). Orbital recurrence was found in 2,5% and 8–12% of cases with extrascleral extension had orbital recurrence. This appeared at an average of 2 years after enucleation and 10% of metastases appeared within the first 6 months post-operatively, more than half within 3 years. The peak incidence was during the first year after enucleation. No second peak was observed. However, metastases appeared even after 23 years. The probability of being alive without metastases after 25 years was found to be 40%, assuming that the patient did not die of another cause. The prognosis was estimated using various clinical and histopathological parameters. Women below the age of 40 had a better prognosis than women above that age. Small tumours, spindle shaped cells, no invasion and low pigment content of tumour were all in favour of a good prognosis. Of the iris melanomas from the period dealt with, only one died with metastasis. The present lively discussion on early enucleation or conservative management is reported and finally the attitude of the Ophthalmic Tumour Centre towards therapy is indicated.

On the Occurrence and Structure of Choanocyte-like Cells in Some Echinoderms

Abstract: Choanocyte-like cells with a collar of regularly arranged cylindrical microvilli around the base of the flagellum were observed in the ciliary bands of the Brachiolaria larva of Asterias rubens. The ambulacral ampullae and coelomic epithelia of adult Asterias and coelomic epithelia of Mesothuria contain similar cells with radial lamellae instead of cylindrical microvilli. Other similar but more modified types of cells, in which the inner edges of the radiating lamellae could be recognized as longitudinal ridges in the wall of a cylindrical flagellar pit, were found in ambulacral ampullae of Porania and in coelomic epithelia of Stichopus. Distinct indications of phagocytosis were seen in most of these cells. The present report together with previously published data lend support to the idea, that the choanocyte is a fundamental cell type in metazoans, probably derived phylogenetically from some flagellate ancestor.

Contraction times of twitches evoked by H-reflexes.

Abstract: Isometric twitches of the same amplitude were initiated in the human soleus muscle by near threshold H-reflexes and by stimuli to the efferent nerve (M-responses) or to the end-plate zone. The time to peak-force was longer in reflex than in directly activated twitches: The range was 84 to 130 msec and 52 to 100 msec, respectively (36–37°C).

Effects of Potassium and of Glutamate on Swelling and on Sodium and Potassium Content in Brain-Cortex Slices from Adult Rats

Abstract: Effects of potassium concentrations, varied systematically between 5 and 85 mM, on swelling and contents of potassium and sodium have been studied. The rectilinear rise of the potassium content and the chloride-dependent increase in swelling observed by other authors are confirmed. Furthermore it is demonstrated that: 1. the potassium-induced increase in swelling is dependent upon the presence of sodium in the medium; 2. the sodium content decreases significantly when the external potassium concentration is raised from 5–20 mM (a further rise to 50 mM causes a considerable increase which is not dependent on the swelling); 3. under conditions when no swelling occurs, the potassium content in the tissue shows a relative decline when the external potassium concentration is raised from 20–50 mM; an increase from 5–20 mM causes on the other hand, a steeper increase in potassium concentration than can be explained by diffusion; 4. the glutamate-induced swelling occurs in the absence of chloride in the medium, but is sodium-dependent; and 5. the concentrations of potassium required to cause the increase of swelling are identical to those previously observed to lead to a stimulation of oxygen uptake.

Climatic Oscillations 1200–2000 AD

Abstract: THE idea of using the isotopic composition of glacier ice as a climatic indicator was proposed in 19541. The method is based on the fact that the concentration of heavy stable isotopes (deuterium and oxygen-18) in high polar snow increases with the temperature of formation of the snow1–3. This causes seasonal variations in the isotopic composition of accumulated snow and ice4, as well as long-term variations due to climatic changes5. A unique possibility for studying palaeoclimates was offered when the US Army Cold Region Research and Engineering Laboratory succeeded in recovering a 1,400 metre long surface-to-bottom ice core from Camp Century on the North Greenland ice sheet6. No physical dating method can be applied on the relatively small amounts of ice available, so the age of the various increments of the core had to be calculated by considering a simple ice flow model8. This procedure turned out to be successful, in so far as the climate record that resulted from plotting the δ(18O) data (δ is defined7 as the relative deviation of the 18O/16O ratio of a sample from that of standard mean ocean water) against the calculated ages depicted known climatic events dated by other methods5,9. In addition, unlike other methods, the stable isotope technique applied on the deep ice core gave an unbroken and detailed climatic record spanning probably 100,000 years.

Immunohistochemical identification of pituitary hormone producing cells in the sockeye salmon (Oncorhynchus nerka, Walbaum)

Abstract: Antisera to six mammalian pituitary hormones and a synthetic corticotrophin (Synacthen) were prepared and tested for specificity. The gamma-globulin fractions of the antisera were conjugated with fluorescein isothiocyanate and the labelled antibodies were isolated by column chromatography. Fresh-frozen sections of pituitary glands of adult migratory sockeye salmon (Oncorhynchus nerka) were incubated with the antibody solutions and examined with a fluorescence microscope. Anti-ACTH and anti-Synacthen appeared to be bound by theepsilon cells, whereas anti-prolactin reacted with theeta cells. Anti-GH was bound to the acidophil cells of the proximal pars distalis. Anti-LH reacted with some of the basophil cells of the proximal pars distalis. Antibodies to FSH or TSH failed to react.

Macromolecular physiology of plastids. VI. Changes in membrane structure associated with shifts in the absorption maxima of the chlorophyllous pigments.

Abstract: Dispersal of the prolamellar body tubules into primary lamellar layers has been studied in leaves of dark-grown bean seedlings ( Phaseolus vulgaris L.). Following complete photoconversion of protochlorophyllide the dispersal process can proceed in either light or darkness. The dispersal is reversibly inhibited in leaves at o °C. Above o °C the time course for the dispersal is temperature dependent. The spectral shift of the in vivo absorption maximum of newly formed chlorophyllide from 684 to 672 nm is also inhibited at o °C and the time course is temperature-dependent in a manner similar to that of the membrane dispersal. A causal connexion between the 2 phenomena can thus be suggested. Derangement of the tubular membranes produced by heat treatment or by freezing and thawing in darkness causes the appearance of photoactive protochlorophyllide absorbing at 635 nm. Photoconversion of protochlorophyllide 635 nm results in chlorophyllide absorbing at 672 nm and further dissociation of the membranes. Denaturation of the prolamellar body membranes by heating or by slow thawing results in the formation of photoinactive protochlorophyllide absorbing at 632 nm.

Determination of non-albumin-bound bilirubin in human serum.

Abstract: Determinations of the low equilibrium concentrations of non-albumin-bound unconjugated bilirubin in serum by a kinetic method have been done on normal umbilical cord blood serum, on serum from exchange transfusions of icteric newborns, and on normal adult serum. The concentrations are about 10−9 M in cord serum and in adult serum, and about 10−5 M in the icteric infant sera. The latter shows little correlation between total unconjugated bilirubin and non-bound bilirubin, indicating that there is a considerable variation in the binding of bilirubin to albumin.

Dynamic Coupling Phenomena in Molecular Excited States. II. Autoionization and Predissociation in H 2 , Hd, and D 2

Abstract: Vibrationally induced autoionization and one class of predissociation of electronically excited ${\mathrm{H}}_{2}$ and its isotopes are treated by a perturbed-stationary-state theory. Autoionization and predissociation rates are given for a number of states of ${\mathrm{H}}_{2}$, HD, and ${\mathrm{D}}_{2}$. In addition to direct bound-continuum coupling, consideration is given to effects of higher-order coupling; these effects cause order-of-magnitude changes in isolated cases. The auto-ionization rates vary with principal quantum number $n$ as ${n}^{\ensuremath{-}3}$, directly with vibrational energy $\mathrm{vh}\ensuremath{ u}$, and decrease sharply with vibrational quantum change $\ensuremath{\Delta}v$. As the principal quantum number increases, transitions of successively smaller $\ensuremath{\Delta}v$ become possible; the net effect of this is to override the ${n}^{\ensuremath{-}3}$ dependence in total autoionization rates. Competition between predissociation and autoionization is examined; the two processes show very different dependence on $n$ and $v$, with the consequence that decay in most regions of ($n, v$) space is dominated by one or the other process; but the two mechanisms are competitive for some ($n, v$) states. The isotope effect also is rather different for the two decay processes, enough so that, in effect, the isotope effect amounts to a qualitative change from one mechanism of decay to the other, with mass change.