Showing papers by "Lund University published in 1978"

The interplexiform cell system. I. Synapses of the dopaminergic neurons of the goldfish retina.

Abstract: Interplexiform cells are a class of retinal neuron that extends processes widely in both plexiform layers. In goldfish they contain dopamine and readily take up certain biogenic amines. Two of these amines, 6-hydroxyopamine (6-HDA) and 5, 6-dihydroxytryptamine (5,6-DHT), induce fine structural changes in the neurons that accumulate them, allowing the processes of the cells to be recognized by electron microscopy. Typically, the synaptic vesicles within the processes show electron-dense cores. The terminal cytoplasm may also show increased density, as may the cellular and cytoplasmic membranes, presumably an indication of degenerative changes induced by the drugs. 5, 6-DHT gives more readily observable changes than 6-HDA but labels both dopaminergic and indoleamine-accumulating neurons. The terminals of the indoleamine-accumulating terminals were therefore removed by intraocular injections of 5, 7-dihydroxytryptamine (5, 7-DHT) prior to the labelling with 5, 6-DHT. This procedure allowed an analysis of the dopaminergic terminals without interference by the terminals of the indoleamine-accumulating cells. The dopaminergic neurons were found to make synapses of the conventional type. In the outer plexiform layer they contacted both external horizontal cells and bipolar cell dendrites, but not hotoreceptor terminals or intermediate (rod) horizontal cells. No synapses onto the dopaminergic processes were found in the outer plexiform layer despite an extensive search. In the inner plexiform layer the dopaminergic processes were observed to be both pre- and postsynaptic to amacrine cells and their processes. No synaptic contacts between dopaminergic processes and bipolar cell terminals or ganglion cell dendrites were seen. We conclude that the dopaminergic interplexiform cells provide a centri­fugal pathway for information flow in the retina from inner to outer plexiform layer.

Effects of planktivorous and benthivorous fish on organisms and water chemistry in eutrophic lakes

Abstract: The effects of planktivorous and benthivorous fish on benthic fauna, zooplankton, phytoplankton and water chemistry were studied experimentally in two eutrophic Swedish lakes using cylindrical enclosures. In enclosures in both lakes, dense fish populations resulted in low numbers of benthic fauna and planktonic cladocerans, high concentration of chlorophyll, blooms of blue-green, algae, high pH and low transparency. In the soft-water Lake Trummen, total phosporus increased in the enclosure with fish, but in the hard-water Lake Bysjon total phosphorus decreased simultaneously with precipitation of calcium carbonate. Enclosures without fish had a higher abundance of benthic fauna and large planktonic cladocerans, lower phytoplankton biomass, lower pH and higher transparency.

Influence of food on the bioavailability of drugs.

Abstract: Food intake exerts a complex influence on the bioavailability of drugs. It may interfere not only with tablet disintegration, drug dissolution and drug transit through the gastrointestinal tract, but may also affect the metabolic transformation of drugs in the gastrointestinal wall and in the liver. Different food components can have different effects, and food may interact in opposite ways, even with drugs that are chemically related. Therefore, the net effect of food on drug bioavailability can be predicted only by direct clinical studies of the drug in question. As judged mainly from single meal, single dose studies, food intake enhances the bioavailability of several different drugs, such as propranolol, metoprolol, hydrallazine, hydrochlorothiazide, canrenone (from spironolactone), nitrofurantoin, erythromycin (stearate), dicoumarol, phenytoin and carbamazepine, but reduces that of drugs such as isoniazid, rifampicin, tetracycline, penicillin and ampicillin, while having no consistent effect on the bioavailability of metronidazole, oxazepam, melperone, propylthiouracil, sulphasomidine and sulphonylureas. For some drugs such as digoxin and paracetamol, the rate but not the extent of absorption is reduced. Food may enhance bioavailability even though, or rather because, the rate of gastric emptying is reduced; this is apparently the case with hydrochlorothiazide and nitrofurantoin. The food induced enhancement of bioavailability of propranolol, metoprolol and hydrallazine is probably due to reduced first pass metabolism of these drugs, while food induced improvement of drug dissolution may explain the enhanced bioavailability of carbamazepine, canrenone, dicoumarol and phenytoin. An increased gastrointestinal pH may be in part the cause of the food induced reduction of the bioavailability of drugs such as isoniazid and tetracycline. In addition to single meal effects, repeated intake of protein-rich meals enhance, while carbohydrate-rich meals reduce, the rate of oxidation of antipyrine and theophylline. Moreover, intake of charcoal broiled meat markedly accelerates the oxidation of phenacetin and variably accelerates elimination of theophylline. Thus, food and its components and contaminants may have both short and long term effects on both the absorptive and biotransformation processes influencing systemic availability of drugs.

Climbing fiber microzones in cerebellar vermis and their projection to different groups of cells in the lateral vestibular nucleus.

Abstract: 1. The projections from one of the paths (b-VF-SOCP) in the ventral spino-olivocerebellar system to the cortical b-zone located in the lateral part of the anterior lobe vermis and to the lateral vestibular nucleus (LVN) have been studied in cats with the spinal cord transected at C3 sparing only the contralateral ventral funiculus. The projection to the b-zone was studied by recording climbing fiber responses in single Purkinje cells on stimulation of limb nerves. The projections to the LVN, direct through climbing fiber collaterals and indirect through Purkinje cells, were studied by recordings EPSPs and IPSPs in LVN neurons. 2. The Purkinje cells in the b-zone were arbitrarily divided into five groups with different inputs and occupying different microzones each with a width of about 200 micron. On passing medially across the b-zone the microzones had the following input characteristics: 1. activation exclusively from hindlimb nerves, 2. short-latency activation from hindlimb and long-latency activation from forelimb nerves, 3. short-latency activation from hindlimb and forelimb nerves, 4. short-latency activation from forelimb and long-latency activation from hindlimb nerves, and 5. activation exclusively from forelimb nerves. 3. The five microzones projected to different groups of LVN neurons which occurred intermingled throughout the nucleus. The LVN neurons inhibited from a certain microzone were activated by the collaterals of the climbing fibers projecting to that microzone. 4. The organization of the spino-olivo-cerebello-vestibulo-spinal path is discussed. It is suggested that the microzone and collection of subcortical neurons represent the basic computational unit of the cerebellum.

Applications of linear Dichroism Spectroscopy

Abstract: Linear dichroism is the phenomenon of anisotropic absorption of light. It is shown by materials containing oriented molecules for which the absorption varies with the direction. The absorption intensity is proportional to the square of the scalar product between the electric field vector of the light and a molecule-characteristic transition moment vector, the absorption being maximum when the light vector is polarized parallel to the transition moment and zero when perpendicular to it. Linear dichroism can therefore provide (1) directions of transition moments when the molecule orientation is known (spectroscopic applications), or (2) information on molecular orientation when the transition moments are known (structural applications). Both applications are useful in several chemical systems, but so far the use of linear dichroism has been confined to a relatively small number of specialized laboratories, not least because of a lack of appropriate commercial instruments. Plane-polarized spectra have long been measured on crystals and other well-oriented materials, but systems with less complete orientation have usually been studied by birefringence which has allowed greater sensitivity. Birefringence and linear dichroism are related by the dispersion equations and therefore in principle contain the same basic information. However, linear dichroism is better suited for practical use since it is related in a very simple way to more-or-less well-separated quantal transitions, while birefringence is a complicated average over all transitions in the molecule.

Experimental intrinsic healing of flexor tendons based upon synovial fluid nutrition.

Abstract: The healing process of totally cut and subsequently re sutured rabbit flexor tendons kept isolated in the knee joint cavity and free in the synovial fluid was studied by histological and ultrastructural techniques. This experimental model represents a "tissue culture in situ," where the tendon is nourished by diffusion from the synovial fluid only and where no adhesions are formed. Under these conditions there is a proliferation of tendon cells and deposition of collagen resulting in bridging of the suture line. On the basis of these findings, it is assumed that the tendon cells possess an intrinsic potential of repair, provided they obtain a sufficient nutritional supply. In the present experimental model, this nutrition was provided by way of diffusional pathways from the synovial fluid.

Converging projections from the mediodorsal thalamic nucleus and mesencephalic dopaminergic neurons to the neocortex in three species.

Abstract: Previous studies in the rat have shown that the neocortical dopaminergic afferents, originating in the mesencephalon, terminate in those areas of the frontal lobe which receive projections from the mediodorsal thalamic nucleus i.e., the prefrontal cortex. In order to clarify whether this overlap is accidental for the rat or a consistent feature of several species we have compared the projection areas of the ventral tegmental area and the mediodorsal thalamic nucleus in three species, rat, opossum and tree shrew, using HRP injections in combination with glyoxylic acid histofluorescence method. The results have shown, first, that the area innervated by the mediodorsal nucleus of the thalamus is localized in a different part of the frontal lobe in each species: dorsolateral in the opossum, anteromedial, polar and suprarhinal in the rat and frontopolar in the tree shrew. Secondly, this area alone in each species receives projections from the ventral tegmental area. Thirdly, this area alone receives a dense innervation in the deep cortical layers by fluorescent fibres probably containing dopamine. The neighbouring neocortical areas receive afferents neither from the mediodorsal nucleus of the thalamus nor from the ventral mesencephalic tegmentum; their catecholamine innervation is mainly confined to the superficial layers and appears to be of noradrenergic nature. Although the techniques used did not allow a precise determination of the borders of the two projection areas and, therefore, the exact degree of overlap, it appears that mesencephalic dopaminergic innervation is a characteristic feature of the prefrontal cortex in the mammalian brain.

Dopamine and noradrenaline neurons projecting to the septal area in the rat.

Abstract: The organisation of the catecholamine innervation of the rat spetal area was investigated by means of the glyoxylic acid fluorescence method in combination with dopamine uptake studies, lesions and retrograde tracing of horseradish peroxidase. The following catecholamine systems to the septum could be established: 1. The Locus Coreuleus Noradrenergic System. These axons are widespread in the septum forming a moderately dense innervation in the anterior hippocampus, the medial septal nucleus, the nucleus of the diagonal band, and the interstitial nucleus of the stria terminalis, and a sparse innervation in the lateral septal nucleus and the septofimbrial nucleus. 2. The Medulla Oblongata Noradrenergic System. This system originates in the A1, A2 or A3 cell groups, the axons forming a very dense innervation in the ventral part of the interstitial nucleus of the stria terminalis, a moderately dense innervation in the nucleus of the diagonal band and lateral septal nucleus, and a sparse innervation in the medial septal nucleus, the septofimbrial nucleus and the dorsal part of the interstitial nucleus of the stria terminalis. 3. The Mesencephalic Dopaminergic System. This system originates in the medial part of the A10 cell group, the axons forming two distinct terminal patterns. In the first type, smooth axons form pericellular arrangements around non-fluorscent neurons in the lateral septal nucleus. The second type is formed by fine-varicose axons which form a dense band around the fornix in the medial part of the lateral septal nucleus. 4. The Incerto-Hypothalamic Dopaminergic System. These axons most probably originate in cell bodies of the diencephalic A11, A13 and A14 cell groups, and are found in the lateral septal nucleus at the level of the anterior commissure.

Sympathetic nervous control of cerebrospinal fluid production from the choroid plexus.

Abstract: The rabbit choroid plexus, responsible for the bulk production of cerebrospinal fluid, is well supplied by sympathetic nerves emanating in the superior cervical ganglia. Electrical stimulation of these nerves markedly reduces production of cerebrospinal fluid, measured by [14C] inulin dilution during ventricular perfusion, whereas sympathetic denervation enhances the rate of formation.

Synaptic organization of the dopaminergic neurons in the rabbit retina.

Abstract: A number of substances were tested for their ability to label amine-accumulating neurons in the rabbit retina after fixation with OsO4 or glutaraldehyde and OsO4. Useful results were obtained with 5,6-dihydroxytryptamine (5,6-DHT) and 6-hydroxydopamine (6-HDA). Labelled processes were characterized by small (40–50 mm) pleomorphic synaptic vesicles containing electron-dense cores, and at times by swelling of mitochondria and by increased electron density of membranes and cytoplasm. Fluorescence microscopy showed that 5,6-DHT labelled both dopaminergic and indoleamine-accumulating neurons. In most experiments, therefore, the indoleamine-accumulating neurons were removed with 5,7-dihydroxytryptamine. In such retinas the dopaminergic processes labelled by 5,6-DHT were found to make synapses of the conventional type, characterized by an accumulation of synaptic vesicles on the presumed presynaptic side and some aggregation of material on the cytoplasmic side of the synaptic membranes and within the synaptic cleft. The dopaminergic processes were found to contact each other and also non-dopaminergic amacrine cells and their processes. Conventional synapses onto dopaminergic processes were observed from both labelled and unlabelled amacrine processes. The input from labelled neurons was observed on varicose dopaminergic processes whereas input from non-labelled elements was found on the intervaricose parts of the dopaminergic processes. No Contacts of dopaminergic processes with bipolar or ganglion cells were observed. Injections of 6-HDA gave the same results, although this drug gave less distinct labelling which made the observations less decisive than with 5,6-DHT. In retinas treated with 5,6-DHT alone (i.e., in which the indoleamine-accumulating neurons remained) numerous processes were observed which were both pre- and postsynaptic to bipolar terminals. These observations suggest that the indoleamine-accumulating processes synapse with bipolar cells. The results show that the dopaminergic neurons form a network involving only amacrine cells, suggesting a regulatory function for them. By analogy with the dopaminergic interplexiform cells of the goldfish retina, it is suggested that the dopaminergic neurons in the rabbit may regulate lateral inhibitory effects mediated by amacrine cells. Furthermore, the finding that the dopaminergic and indoleamine-accumulating cells apparently have a different synaptic organization suggests that it is appropriate to categorize amacrine cells according to their transmitter content as well as their morphology.

The effect of topical citric acid application on the healing of experimental furcation defects in dogs.

Abstract: Chronic periodontal disease was induced and through-and-through furcation pockets created in mandibular premolars in two groups of beagles consisting of five and six animals respectively. The furcation defects were treated by surgical debridement supplemented with citric acid conditioning of the instrumented root surface. The relative importance of three adjunctive therapeutic measures was assessed. Thus, the effect of systemic antibiotics was evaluated by inter-group comparison. Gelfoam as a matrix support for the blood coagulum during healing was evaluated by intraindividual, contralateral comparisons in one group of animals. Coronal repositioning of the muco-periosteal flaps was evaluated by contralateral comparisons in the second group of animals. Block specimens for histological evaluation were removed six weeks after surgery. A high rate of regeneration and new attachment of the furcations was obtained irrespective of the use of systemic antibiotics, Gelfoam and high or low flap positioning. Thus, topical acid application seems to be the crucial therapeutic factor in achieving new attachment in the present model of through-and-through furcation pockets.

Leu-enkephalin-like material in nerves and enterochromaffin cells in the gut. An immunohistochemical study.

Abstract: The distribution and cellular localization of leu-enkephalin in the gut and pancreas was studied by immunohistochemistry using two different antisera, one specifically directed against leu-enkephalin and the other cross reacting with met-enkephalin. The results were identical with both antisera. In all species examined, enkephalin-immunoreactive material was found in nerves of the smooth muscle, particularly numerous in the myenteric plexus. Here, immunoreactive nerve cell bodies were observed occasionally. In addition, enkephalin-immunoreactive material was demonstrated in gut endocrine cells of chicken, mouse, rat, pig and monkey but not of guinea pig, cat and man. Enkephalin cells were detected also in the exocrine parenchyma of the porcine pancreas. They were rare in the gut of mouse, rat and monkey but numerous in the antrum and duodenum of pig where they were identified as 5-hydroxytryptamine-storing enterochromaffin cells. The enkephalin-containing cells of the porcine antrum and duodenum were defined ultrastructurally by the consecutive semithin/ultrathin section technique. The ultrastructural features were typical of enterochromaffin cells, the most characteristic ones being the irregular shape and high electron density of the cytoplasmic granules. The immunoreactive material was confined to the cytoplasmic granules.

Leaching rates of heavy metal ions in forest soil

Abstract: The leachability of Mn, Zn, Cd, Ni, V, Cu, Cr, and Pb was studied in two purely organic spruce forest soils: one control soil and one similar soil heavily polluted by Cu and Zn from a brass foundry in southern Sweden Artificial rainwater, acidified to pH 42, 32, and 28 was used in the experiment The 10% residence times, estimated from the experimental data, varied from 3 yr (Mn) to 70 to 90 yr (Pb) in the control soil and from 2 yr (V) to > 200 yr (Ph) in the polluted soil with a precipitation water of pH 42 Residence times for most elements studied (except V and Cr) decreased with pH of precipitation water

The Influence of Photoperiod and Temperature on the Development of Frost Hardiness in Seedlings of Pinus silvestris and Picea abies

Abstract: The influence of short days and low temperature on the development of frost hardiness in seedlings of Scots pine (Pinus silvestris L.) and Norway spruce [Picea abies (L.) Karst.], grown for 6 months in glasshouses and climate chambers, was investigated. The degree of hardiness was estimated by freezing the shoots of the seedlings to predetermined temperatures. After 8 weeks in a glasshouse the viability of the seedlings was determined by establishing bud flushing. The most effective climate for the development of frost hardiness was short days (SD) and low temperature (2°C); the next most effective was SD and room temperature (20°C). However, long days (LD) and low temperature also had a marked effect on the development of hardiness. A combination of 3 weeks’treatment with SD and 20°C, and 3 weeks with SD and 2°C gave the same results as 6 weeks with SD and 2°C. The results clearly demonstrate the importance of the photoperiod prior to low temperature for the development of frost hardiness. In conclusion both short days and low temperature induce frost hardiness development. Probably this occurs by initiation of different processes in the two cases. The degree of frost hardiness development appears to depend on the sum of these different processes and on the timing between them.

Changes in plasma high density lipoproteins in chronic male alcoholics during and after abuse.

Abstract: Alterations in plasma high density lipoproteins (HDL) were studied in thirty-eight male chronic alcoholics. Twenty-four (63%) of the patients had increased HDL protein (measured immunochemically) and twenty-five (66%) had increased HDL cholesterol (determined after polyanion precipitation of very low density lipoproteins (VLDL) and low density lipoproteins (LDL)). A statistically significant correlation was found between HDL protein and HDL cholesterol (r = 0.39). gamma-Glutamyltransferase (GT) was elevated in eighteen (47%) of the alcoholics. No significant correlations were found between GT and HDL protein or HDL cholesterol. The increase in HDL, as studied by rate zonal ultracentrifugation, was heterogeneous with changes in the HDL2 as well as HDL3 subfractions. It is suggested that determination of HDL total cholesterol, in combination with GT, may represent a valuable and sensitive test for detection of alcoholism.

The Spectrum and Term System of Fe II

Abstract: The spectrum of singly ionized iron, Fe II, has been recorded in the wavelength regions 900-2200 A and 4800-11200 A by means of a pulsed hollow-cathode discharge. In the vacuum-ultraviolet region identifications are given for 1358 lines. The list for the region above 4800 A contains 1564 observed lines, 1341 of which are identified. In the 2200-4800 A range about 350 lines in the line list published by Dobbie in 1938 have been newly identified. On the basis of interferometric measurements made by G. Norlen of 350 lines a recalculation of the whole term system has been performed. Altogether 576 energy levels are now known in Fe II, some 250 of which are the results of the present analysis. The levels belong to the configurations (3d6)4s, 5s, 6s, 4p, 5p, 3d, 4d, 5d, 4f and (3d54s)4s, 5s, 4p, 4d and 3d54p2. Theoretical predictions of the structure of the (3d64p + 3d65p + 3d54s4p) complex by J. Sinzelle and J. F. Wyart are in good agreement with the observations. The ionization energy has been determined to 130 563 ± 10 cm-1.

The application of the drop volume technique to measurements of the adsorption of proteins at interfaces

Abstract: A new procedure for the application of the drop volume technique to measurements of the rate of adsorption of proteins at interfaces has been developed. The mode of adsorption of the proteins lysozyme, β-lactoglobulin and bovine serum albumin (BSA) at the air-water interface has been measured with the drop volume method and has been compared to measurements with the Wilhelmy plate technique. Due to surface enlargement of the drop throughout the process of the surface tension decay, slower kinetics of the adsorption process is obtained by the drop volume method compared to the Wilhelmy plate technique, and the proteins investigated were differently sensitive to this surface expansion. The adsorption process of the proteins has been evaluated in terms of different rate-determining processes. Different intermediate states between the native and the denatured forms have been observed.