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  • Electronic Resource  (8)
  • Hippocampus  (5)
  • diabetic nephropathy  (2)
  • Altimetry  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Automated analysis of rhythmicity of physiologically identified hippocampal formation neurons (1980)
    Springer
    Experimental brain research 38 (1980), S. 205-219 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Analysis of theta cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The participation of physiologically identified hippocampal neurons in spontaneous and hypothalamically induced theta activity was studied in rabbits lightly anaesthetized with urethane. Dentate granule cells were identified by their orthodromic response to perforant path stimulation, CA1 and CA3 pyramids by antidromic activation from the alveus and Schaffer collaterals, respectively, and basket cells by their response to increasing orthodromic activation. The discharges of many hippocampal cells were grossly correlated to the pattern of slow wave activity. Few cells were spontaneously active during irregular slow wave activity. With the appearance of rhythmical slow wave activity of 4–6 Hz, the unit discharges also increased in frequency. Dentate granule cells had the lowest threshold for activation and also a longer duration of the increased discharge frequency, compared to other cell types. There was a characteristic pattern of transition for dentate granule cells and CA1 pyramidal cells from a silent to an active state. The cell discharges paralleled the changes in amplitude, regularity, and frequency of theta slow waves. Large-amplitude, high-frequency theta was correlated with rhythmic burst discharges of up to 2–3 spikes per burst. As theta amplitude and frequency decreased, the number of spikes per burst reduced until only regular single spikes occurred. When theta activity was replaced by irregular slow wave activity, the cell discharges became irregular and sometimes ceased entirely. At high levels of activation, CA1 pyramids often showed clusters of high-frequency discharges with declining amplitude (complex spikes). For each cell a cycle histogram was constructed, placing the discharges in one of 20 bins according to their time relation to the simultaneously recorded slow theta waves. In addition, by Fourier transformation of the cycle histograms, the technique allowed a quantitative description of the degree and type of rhythmicity. The analysis indicated that virtually all dentate granule cells and CA1 pyramidal cells were phaselocked to the negative portion of the theta waves recorded from the corresponding region. The cells differed in their degree of coupling, as expressed by the modulation index of their cyclic histograms. Dentate granule cells had higher modulation indices than the CA1 pyramids. There was a suggestion that basket cells and CA3 cells had smaller modulation indices, but the low number of cells recorded mitigate against any strong conclusions. The results are interpreted as corroborating earlier findings that the dentate granule region and the CA1 pyramidal region are the main generators of hippocampal theta activity. A “size principle” was proposed to explain the role of synaptic depolarizing pressure in the rhythmic activation of hippocampal neurons and the fact that small neurons (dentate granules and CA1 pyramids) were better driven than larger neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236742
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  • 2
    Electronic Resource
    Electronic Resource
    Apolipoprotein(a) and cardiovascular disease in Type 2 (non-insulin-dependent) diabetic patients with and without diabetic nephropathy (1993)
    Springer
    Diabetologia 36 (1993), S. 438-444 
    Details
    ISSN: 1432-0428
    Keywords: Type 2 (non-insulin-dependent) diabetes mellitus ; diabetic nephropathy ; apolipoprotein(a) ; cardiovascular disease ; lipid metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relative mortality from cardiovascular disease is on average increased five-fold in Type 2 (non-insulin-dependent) diabetic patients with diabetic nephropathy compared to non-diabetic subjects. We assessed the possible contribution of dyslipidaemia in general and elevated serum apolipoprotein(a) (apo(a)) in particular. Type 2 diabetic patients with normo-, micro- and macroalbuminuria were compared with healthy subjects. Each group consisted of 37 subjects matched for age, sex and diabetes duration. Serum creatinine in the nephropathy group was 105 (54–740) Μmol/l. The prevalence of ischaemic heart disease (resting ECG, Minnesota, Rating Scale) was 57, 35, 19 and 2% in macro-, micro- and normoalbuminuric diabetic patients and healthy subjects, respectively. The prevalence of ischaemic heart disease was higher in all diabetic groups as compared to healthy subjects (p〈0.05), and higher in macroalbuminuric as compared to normoalbuminuric diabetic patients (p〈0.01). There was no significant difference between apo(a) in the four groups: 161 (10–1370), 191 (10–2080), 147 (10–942), 102 (10–1440) U/l (median (range)) in macro-, micro- and normoalbuminuric groups and healthy subjects. Serum total-cholesterol, HDL-cholesterol and LDL-cholesterol were not significantly different when comparing healthy subjects and each diabetic group. Apolipoprotein A-I was lower (p〈0.05) in all diabetic groups as compared to healthy subjects (nephropathy vs healthy subjects): 1.50±0.25 vs 1.69±0.32 g/l (mean ± SD). Triglyceride was higher (p〈0.05) in patients with nephropathy and microalbuminuria as compared to healthy subjects (nephropathy vs healthy subjects): 2.01 (0.66–14.7) vs 1.09 (0.41–2.75) mmol/l (median (range)). Apolipoprotein B was higher (p〈0.02) in patients with nephropathy as compared to the other three groups (nephropathy vs healthy subjects): 1.54±0.47 vs 1.33±0.30 g/l. In conclusion, our case-control study has confirmed that Type 2 diabetic patients with increased urinary albumin excretion frequently suffer from dyslipidaemia and cardiovascular disease. However, our study revealed no significant elevation in serum concentration of apo(a) in patients with diabetic nephropathy, but numbers were small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402281
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  • 3
    Electronic Resource
    Electronic Resource
    Plasma lipoproteins and renal function during simvastatin treatment in diabetic nephropathy (1992)
    Springer
    Diabetologia 35 (1992), S. 447-451 
    Details
    ISSN: 1432-0428
    Keywords: Plasma lipoproteins ; albuminuria ; diabetic nephropathy ; glomerular filtration rate ; Type 1 (insulin-dependent) diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of this study was to assess the effect of simvastatin on plasma lipoproteins and renal function in hypercholesterolaemic Type 1 (insulin-dependent) diabetic patients with diabetic nephropathy. Twenty-six hypercholesterolaemic (total cholesterol ≽ 5.5 mmol/l) Type 1 diabetic patients with nephropathy were enrolled in a double-blind randomized placebo-controlled study for 12 weeks. The active treatment group (n -14) received simvastatin (10–20 mg/day) for 12 weeks while the remaining 12 patients received treatment with placebo. The results during simvastatin treatment (baseline vs 12 weeks): total cholesterol 6.6 vs 4.8 mmol/1 (p 〈 0.01), LDL-cholesterol 4.25 vs 2.57 mmol/l (p 〈 0.01) and apolipoprotein B 1.37 vs 1.06 mmol/l (p 〈 0.01). HDL-cholesterol, and apolipoprotein A-I remained unchanged. Total cholesterol, LDL-cholesterol, HDL-cholesterol, apolipoprotein A–I, apolipoprotein B remained unchanged during placebo treatment. Albuminuria measured during the simvastatin and the placebo treatment (baseline vs 12 weeks) (the data are logarithmically transformed before analysis because of their positively skewed transformation; geometric mean (×/÷ antilog SE) is indicated) was 458 (×/÷ 1.58) vs 393 (×/÷ 1.61) and 481 (×/÷ 1.62) vs 368 (×/÷ 1.78 μg/min (NS). Glomerular filtration rate during simvastatin and placebo treatment (baseline vs 12 weeks) was 64 vs 63 and 72 vs 74 ml·min−1·1.73 m−2, respectively. Two patients receiving simvastatin treatment were withdrawn, one due to gastrointestinal side effects and one due to myalgia. In conclusion, our short-term study in Type 1 diabetic patients with diabetic nephropathy did not reveal any beneficial effect on albuminuria despite a striking lipid-lowering effect of simvastatin in diabetic nephropathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02342442
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  • 4
    Electronic Resource
    Electronic Resource
    Mode of activation of hippocampal pyramidal cells by excitatory synapses on dendrites (1966)
    Springer
    Experimental brain research 2 (1966), S. 247-260 
    Details
    ISSN: 1432-1106
    Keywords: Synaptic excitation ; Hippocampus ; Pyramidal cells ; Dendritic activation ; Cat ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following selective activation of four afferent paths that terminate exclusively on dendrites, only a small proportion of pyramidal cells in the hippocampal fields CA1 and CA3 discharged impulses. Following a single afferent volley, an EPSP was never observed even in cells synaptically excited. On tetanic stimulation (about 10/sec), a large EPSP developed, but this was not a prerequisite for an action potential. Studies of the extracellular field potentials corresponding to the EPSP and the population spike potential, indicated that the EPSP was generated across the dendritic membrane and that the spike was initiated in the neighbouring part of the dendritic tree, propagating from there along the thicker dendrites towards the soma. This conduction had an average velocity of 0.4m/sec, and, presumably, a relatively low safety factor. In certain cases, the intrasomatic electrode recorded small all-or-nothing spikes which presumably were generated in the dendritic tree. These small spikes (D-spikes) invaded the soma only if assisted by some additional depolarization, for example by frequency potentiation of excitatory synapses. The results indicate two functional types of pyramidal dendrites, the conducting and the synaptic type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236716
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of sodium ions on penicillin-induced epileptiform activity in vitro (1982)
    Springer
    Experimental brain research 47 (1982), S. 154-157 
    Details
    ISSN: 1432-1106
    Keywords: Sodium ; Epileptiform activity ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intra- and extracellular recordings were obtained from the CA1 region of guinea pig hippocampal slices maintained in vitro. We studied the effect of reducing the extracellular sodium concentration on penicillin-induced epileptiform responses. In control experiments, Tris and choline were assayed as sodium substitutes. Choline was found unsuitable, since it induced repetitive firing in the absence of any convulsant agent. Replacement of 50% of the extracellular sodium ([Na+]o) with Tris reduced the amplitude of the presynaptic fiber volley, the field EPSP, and the population spike. Intracellular studies showed that when [Na+]o was lowered, action-potential amplitudes were reversibly depressed by an amount close to that predicted by the Nernst relation. Orthodromically elicited epileptiform discharges, induced by penicillin, were reduced in a low-sodium medium when constant stimulus currents were employed. If orthodromic stimulus strengths in normal and low-sodium states were equated on the basis of the field-EPSP amplitude, no significant diminution of the depolarizing-wave component of the epileptiform response was observed. These results suggest that a synaptic component underlies penicillin-induced epileptiform discharges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235899
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  • 6
    Electronic Resource
    Electronic Resource
    Location and identification of excitatory synapses on hippoeampal pyramidal cells (1966)
    Springer
    Experimental brain research 1 (1966), S. 236-248 
    Details
    ISSN: 1432-1106
    Keywords: Excitatory synapses ; Hippocampus ; Cat, Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. In rabbits and cats anaesthetized by urethane-chloralose or pentobarbital sodium, stimulation of the commissural afferent pathway produced a negative field potential with maximal amplitude in the CA3 basal dendritic layer, and with a latency indicative of monosynaptic activation of excitatory synapses on the basal dendrites. 2. Mossy fibre stimulation resulted in a similar field potential restricted to the mossy fibre layer. Comparable negative field potentials were found in the layer of apical dendrites in CA1 in response to commissural and Schaffer collateral stimulation, suggesting a dendritic location of these synapses. 3. All negative field potentials grew in amplitude on tetanic stimulation, to produce large extracellular spikes, indicating their association with excitatory synaptic activity. 4. Usually, all pathways employed failed to produce EPSPs on single shock stimulation, in spite of their capability of discharging the cells, suggesting that the synaptic depolarization takes place at some distance from the soma. 5. Electron microscopy of degenerated commissural afferent fibres showed them to make contact with spines or the smooth surface of thin dendrites. The indentification of the postsynaptic element as pyramidal cell dendrite was ascertained. The mossy fibres end on ramified dendritic spines in CA3. 6. By comparison with normal electron micrographs, all the pathways, shown physiologically to be excitatory, terminate on thin dendrites, the contacts being of type 1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234344
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  • 7
    Electronic Resource
    Electronic Resource
    Organization of the hippocampal output (1973)
    Springer
    Experimental brain research 17 (1973), S. 152-168 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Output fibres ; Cat and rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The spatial organization of the efferent projections of CA1 and CA3 hippocampal pyramids has been studied using recordings of fibre volleys, orthodromic and antidromic population spikes and synaptic field potentials, following microelectrode stimulation of the fimbria, CA1 alveus, or subiculum. 2. Only CA3 pyramidal cells were found to send their axons into the fimbria. In the septal two thirds of the hippocampus the CA1 pyramidal cells project in a caudal direction to the pyramidal part of the subiculum. The temporal third was not explored for technical reasons. 3. Fimbrial fibres are arranged in a strictly parallel fashion, the rostro-medial CA3 cells distributing their axons near to the hippocampus, while those located at the temporal extreme distribute their axons to the outer edge of the fimbria. The organization of the Schaffer collaterals and the projections of the CA1 cells consisted of parallel lamellae, oriented nearly transversely to the longitudinal axis of the hippocampus in rabbits (more obliquely in cats). The findings indicate that CA3 cell discharge via the Schaffer collaterals represents a major input driving the CA1 cells. 4. The dichotomy with regard to hippocampal output suggests that the CA3 and CA1 regions of the hippocampus may subserve different functions, thus probably participating differentially in various behavioural situations. 5. This organization makes it possible to study the behaviour of animals with selective and regional de-efferentation of the CA3 or of the CA1 regions by making discrete lesions in the fimbria and alveus, respectively. Alternatively, recording the fibre volley from the fimbria may provide a useful monitor of the output of the CA3 region during different behaviours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235025
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  • 8
    Electronic Resource
    Electronic Resource
    Precise ERS-2 orbit determination using SLR, PRARE, and RA observations (1998)
    Springer
    Journal of geodesy 72 (1998), S. 421-429 
    Details
    ISSN: 1432-1394
    Keywords: Key words. ERS-2 ; SLR ; PRARE ; Altimetry ; Orbit determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract. The second European Remote Sensing satellite ERS-2, launched in 1995, is supported by satellite laser ranging (SLR), the German precise range and range-rate equipment (PRARE) microwave tracking system, and radar altimetry (RA). SLR, PRARE and crossover RA observations (XO/RA) from May, June, and July 1996 have been analyzed using the GEOSAT software developed at Forsvarets forskningsinstitutt (FFI, The Norwegian defence research establishment). Orbits computed with the JGM3 gravity model and the more recent EGM96 gravity model have been compared with orbits from other analysis centers. Based on these comparisons in addition to the post-fit observation residuals, and results from internal orbital overlaps, we conclude that the radial component of the ERS-2 orbit can be determined with a precision of 6 cm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001900050181
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