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  • 1980-1984  (1.335)
  • 1980  (1.335)
  • Life and Medical Sciences  (768)
  • Chemical Engineering  (478)
  • Rat  (88)
  • Nuclear reactions
Datenquelle
Materialart
Erscheinungszeitraum
  • 1980-1984  (1.335)
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Effect of 5,7-dihydroxytryptamine on the development of tolerance to ethanol (1980)
    Springer
    Psychopharmacology 67 (1980), S. 143-146 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Ethanol ; Tolerance ; 5,7-Dihydroxytryptamine ; 5-HT ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract 5,7-Dihydroxytryptamine (5,7-DHT) or the vehicle was administered once into both lateral ventricles of the rat. Desmethylimipramine (DMI) was administered IP prior to the intraventricular injection of 5,7-DHT to prevent the destruction of norepinephrine (NE) terminals. Following recovery from surgery, ethanol (5 g/kg, PO) or isocaloric sucrose was given daily for 25 days. Tests at 5-day intervals showed that chronic ethanol treatment produced tolerance to the motor impairment on the moving belt test and to hypothermic effects of ethanol. The 5,7-DHT treatment did not alter either the motor impairment or hypothermia produced by the initial dose of ethanol. However, 5,7-DHT treatment produced a 75% depletion of brain serotonin (5-HT) without altering NE concentration and retarded the development of tolerance to ethanol in both measurements. This study with a specific central depletor of 5-HT, without alteration in NE concentration, extends and supports our hypothesis that brain 5-HT modulates the development of tolerance to ethanol.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00431969
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  • 2
    Digitale Medien
    Digitale Medien
    Following several days of continuous administration d-amphetamine acquires hallucinogenlike properties (1980)
    Springer
    Psychopharmacology 68 (1980), S. 197-200 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Continuous amphetamine ; Hallucinogens ; Limb flicks ; Shakes ; Grooming ; Model psychosis ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rats injected with LSD or mescaline show the behavioral syndrome which has been previously reported following injections of hallucinogens in higher mammals: limb flicks and whole body shakes. Although these behaviors are not elicited by acute injections of amphetamine, they are present in rats which have been pretreated for 108 h with a slow-release amphetamine pellet, given a 12h rest period, and then injected with d-amphetamine. Such pellet-pretreated animals also groom their body surface excessively. We propose that this novel syndrome which follows continuous amphetamine administration can serve as an animal model of the type of amphetamine psychosis that is produced by a similar drug regimen in humans.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00432141
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  • 3
    Digitale Medien
    Digitale Medien
    Metrazol produces conditioned taste aversion in rats (1980)
    Springer
    Psychopharmacology 68 (1980), S. 257-259 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Metrazol ; Conditioned taste aversion ; Rat ; Two bottle test preference ; Saccharin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Employing a two bottle drinking procedure where an animal's preference is measured between plain water and a novel fluid, it was found that the convulsant drug Metrazol produced a conditioned taste aversion to saccharin. This finding is contrary to that of previous reports and highlights the sensitivity of the two bottle method in detecting a taste aversion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00428112
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  • 4
    Digitale Medien
    Digitale Medien
    Differential effects of naloxone against the diazepam-induced release of behavior in rats in three aversive situations (1980)
    Springer
    Psychopharmacology 69 (1980), S. 101-105 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Diazepam ; Naloxone ; Behavioral inhibition ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of naloxone on diazepam-induced release of behavior in aversive situations were investigated in rats. Naloxone (0.5 and 1 mg/kg-1) suppressed diazepam-induced eating in an unfamiliar situation and reduced (1 mg/kg-1) spontaneous food intake. Naloxone (1 mg/kg-1) canceled the increased lever pressing produced by diazepam in a conflict procedure in which one electric shock was delivered at each seventh press. Naloxone (1 mg/kg-1) failed to reverse the enhanced responding for food induced by diazepam in the presence of a signal previously paired with electric foot shocks. In this situation, naloxone alone reinforced the behavioral suppression. These results suggest that transmission mediated by opiate peptides may be involved in only some ‘disinhibitory’ effects of benzodiazepines. In addition, such a peptidergic transmission may play a role in the control of stress-induced behavioral suppression.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00426529
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  • 5
    Digitale Medien
    Digitale Medien
    The effects of diphenylhydantoin on rat behavior (1980)
    Springer
    Psychopharmacology 69 (1980), S. 183-185 
    Details
    ISSN: 1432-2072
    Schlagwort(e): DPH ; Genral activity ; Stereotypy ; Supersensitivity ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Animals were administered increasing doses of diphenylhydantoin (DPH) for 20 days. During withdrawal they were observed in an open field. The results suggest that chronic DPH administration leads to a central supersensitivity phenomenon. Possible interference of DPH with dopaminergic systems was discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00427647
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  • 6
    Digitale Medien
    Digitale Medien
    An observational method for quantifying the behavioural effects of dopamine agonists: Contrasting effects of d-Amphetamine and apomorphine (1980)
    Springer
    Psychopharmacology 69 (1980), S. 253-259 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Rating scales ; Photocell activity cages ; Measurement ; Stereotypy ; d-Amphetamine ; Apomorphine ; Dopamine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A novel means of measuring and analysing behavioural effects of dopamine agonists is described and illustrated by a comparison of the effects of d-amphetamine and apomorphine in the rat. d-Amphetamine (0–15 mg/kg IP) produced significant dose- and time-dependent changes in responses such as locomotion, rearing and sniffing, but not in licking or gnawing. In contrast, apomorphine (0–5 mg/kg SC) produced significant increases in licking and gnawing, as well as in locomotion and sniffing, but no changes in rearing. The results are discussed in comparison with those obtained by other methods, such as photocell beam interruptions or stereotypy rating scales, and may be of importance in elucidating the functions of the forebrain dopamine projections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00433091
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  • 7
    Digitale Medien
    Digitale Medien
    Firing characteristics of neurons mediating optokinetic responses to rat's vestibular neurons (1980)
    Springer
    Pflügers Archiv 386 (1980), S. 221-230 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Optokinetic system ; Pretectum ; Visual vestibular convergence ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract 1) The responses of single units in the pretectum (Pt) and in the n. reticularis tegmenti pontis (NRTP) to constant velocity horizontal rotation (0.25–60 deg/s) of a large-field visual pattern were studied in immobilized, non-anesthetized DA-HAN rats. In addition, responses of Pt and NRTP neurons to pure vestibular stimuli (rotation in the dark) were studied. 2) Pt neurons showed seven response types to optokinetic stimulation (Table 1). The most frequent response (48%) consisted of a very rapid increase in firing to steady state on temporonasal motion stimulation of the contralateral eye; nasotemporal stimuli yielded no change in resting rate as did stimulation of the ipsilateral eye. The response maximum occurred at a retinal slip velocity of 1 deg/s. None of the Pt units tested responded to pure vestibular stimuli. 3) NRTP neurons — as Pt units — most frequently (43%) increased their discharge rate on temporonasal stimulation of the contralateral eye and maintained a constant resting rate during nasotemporal motion. Peak response amplitudes also occurred with retinal slip velocities of 1 deg/s. Contrary to the fast time-to-peak of the responses of Pt neurons NRTP units showed a slow rise in frequency of firing to peak response levels. 4) NRTP neurons responded to pure vestibular stimuli (horizontal angular acceleration in the dark). The vestibular responses were synergistic with those evoked in the same neurons by optokinetic stimuli. Thus, the most frequently encountered type of optokinetic response (s. above) showed a type II vestibular response. 5) Comparison of OKN and Vn optokinetic responses with those of Pt and NRTP suggests that the unidirectional-selective Pt and NRTP neurons are important links in the central optokinetic path. In addition, the NRTP may represent the site at which the retinal slip signal and the eye velocity signal converge. This convergence has been postulated in models of the system [12].
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00587472
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  • 8
    Digitale Medien
    Digitale Medien
    Dynamics of tubuloglomerular feedback adaptation to acute and chronic changes in body fluid volume (1980)
    Springer
    Pflügers Archiv 387 (1980), S. 39-45 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Rat ; Micropuncture ; Tubuloglomerular feedback ; DOCA-salt treatment ; Extracellular volume
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Experiments were performed in anesthetized rats to investigate the time course of the adaptive changes in tubuloglomerular feedback reactivity and juxtaglomerular renin activity induced by DOCA and NaCl loading (isotonic saline as drinking fluid plus daily injections of 25 mg/kg DOCA). In these DOCA escaped rats we studied further the effect of acute volume depletion and repletion on the magnitude of feedback responses. A significant reduction of feedback reactivity was found on the fifth day after starting the DOCA-salt treatment with maximum depression being established after two weeks. In contrast, significant reduction of juxtaglomerular renin content required 10 days and maximum depression three weeks of DOCA-salt administration. In DOCA-salt treated animals with severely curtailed feedback responses acute volume depletion was induced by a single injection of furosemide (10 mg/kg) leading to an excretion of 0.49 ±0.17 mEq sodium and a mean decrease of body weight of 2.17±0.22% over a period of 60–70 min. Mean feedback response (expressed as percent change of early proximal flow rate caused by elevating loop of Henle flow rate from zero to 40 nl/min) was −43.9 ±4.0%, significantly greater than in the pre-depletion phase and indistinguishable from responses seen in normal control rats. Repletion of extracellular volume by infusing HCO3-Ringer solution over 20 min induced a reduction in feedback responsivity to −12.0±2.9%. Plasma and juxtaglomerular renin concentration increased with volume depletion and decreased with volume repletion, but remained considerably lower than observed in normal control rats. Our results suggest that the tubuloglomerular feedback system responds to acute alterations in extracellular volume with rapid adaptations in its reactivity which is consistent with its role in the control of sodium excretion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00580842
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  • 9
    Digitale Medien
    Digitale Medien
    Hepatic vein catheterization in the rat (1980)
    Springer
    Pflügers Archiv 387 (1980), S. 67-68 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Hepatic vein ; Catheterization ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A procedure for catheterization of a right hepatic vein is described in the rat. The procedure is based on the observation that, when the posterior half of the body is bent to the left, a right hepatic vein is aligned with the axis of anterior vena cava and posterior vena cava. A catheter, inserted in the right jugular vein and fitted with a rectilinear mandrel, is guided into the right auricle, the suprahepatic segment of posterior vena cava and a right hepatic vein. Successful catheterization of a right hepatic vein has been obtained in 47 out of 50 animals in which the procedure has been performed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00580846
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  • 10
    Digitale Medien
    Digitale Medien
    Secretin and VIP-stimulated adenylate cyclase from rat heart (1980)
    Springer
    Pflügers Archiv 389 (1980), S. 21-27 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Secretin ; Vasoactive intestinal peptide ; Glucagon ; Isoproterenol ; Adenylate cyclase ; Heart ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Membrane adenylate cyclase from rat heart was activated by the two gut peptides secretin and vasoactive intestinal peptide (VIP), glucagon, and the β-adrenergic drug isoproterenol, in the presence of guanosine 5′-triphosphate (GTP). With all the stimuli tested, the optimal magnesium concentration was 5 mM, i.e. in excess over the 0.5 mM ATP substrate concentration and 0.01 mM GTP used as cofactor. Under these conditions, half-maximal adenylate cyclase activation with glucagon, secretin, and VIP was achieved at concentrations of 0.5, 0.5 and 1.0 μM, respectively. Data obtained with the secretin (7–27) fragment, a secretin antagonist, indicate that secretin and VIP acted on the same binding sites, which differed from glucagon binding sites. Structural requirements for secretin activation of cardiac adenylate cyclase were evaluated by comparing the potency and efficacy of parent peptides and synthetic analogs. The gastric inhibitory peptide GIP was inactive. When using 13 mono-or bi-substituted analogs, it appeared that amino acids in positions 1, 2, 3, 4 and 6 were of major importance while those in position 5 and 11 played a relatively minor role.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00587924
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  • 11
    Digitale Medien
    Digitale Medien
    Changes in the glomerular filtration rate after unilateral nephrectomy in rats (1980)
    Springer
    Pflügers Archiv 385 (1980), S. 161-165 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Glomerular filtration rate ; Unilateral nephrectomy ; Compensatory hypertrophy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Changes in the glomerular filtration rate (GFR) were studied in rats, 4 h to 4 weeks after unilateral nephrectomy (NX). The GFR was determined with a technique using51Cr-EDTA and a single timed blood sample. The GFR determined in this way corresponded with the GFR calculated by two compartment analysis and with the plasma levels of creatinine and urea. Increases in the GFR, compared with half the GFR of sham operated rats, were observed as early as 4 h after NX. This increase was entirely due to an increase in the GFR per gram of kidney, since no increase in kidney weight was observed at that time. After the initial increase, the GFR remained at that level during the first 48 h after NX. At 48 h a significant increase in kidney weight per 100 g body weight had taken place. The longterm changes in the GFR amounted to an increase of about 80% of that of sham operated rats after 3–4 weeks. After 4 weeks, the increase in the GFR of the remaining kidney was due to an increase in kidney weight of 35% as well as an increase in the GFR per gram of kidney of 20%. These data indicate that the increase in the GFR of the remaining kidney after unilateral NX occurs rapidly and is independent of an increase in kidney weight. Compensatory hypertrophy develops at a later stage and helps to maintain the increased function of the single remaining kidney.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00588697
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  • 12
    Digitale Medien
    Digitale Medien
    Increase in plasma renin activity, water intake and blood pressure following application and reapplication of a renal artery clip (1980)
    Springer
    Pflügers Archiv 385 (1980), S. 211-215 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Rat ; Renal hypertension ; Plasma renin activity ; Water intake ; Declipping ; Reclipping ; Converting enzyme inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Application of a renal artery clip in rats with an undisturbed contralateral kidney caused a sustained increase in blood pressure and a transient rise of plasma renin activity and water intake. The response of blood pressure, plasma renin activity and water intake was augmented after reapplication of the clip to normotensive declipped rats (renal hypertensive rats, from which the clip had been removed 24 h before the reapplication). The time-course of the changes of blood pressure, plasma renin activity and water intake were similar after the initial application as after reapplication of the clip. Administration of an inhibitor (SQ 14.225) of the converting enzyme abolished the increase in blood pressure and water intake after reapplication of the clip. These data indicate a critical role of renin in the rise of blood pressure and water intake after initial application of a renal artery clip as well as after reapplication of the clip to declipped rats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00647459
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  • 13
    Digitale Medien
    Digitale Medien
    Oxygen supply of the brain cortex (rat) during severe hypoglycemia (1980)
    Springer
    Pflügers Archiv 387 (1980), S. 121-126 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Local tissuepO2 ; Hypoglycemia ; Brain cortex ; ECoG ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Oxygen supply of the brain cortex together with changes in the electrocorticogram (ECoG) were investigated during and after insulin induced hypoglycemia in 13 anaesthetized rats. Local oxygen partial pressures (pO2) on the parietal cortex were continuously measured with a multiwire surface electrode of the Clark type. During early hypoglycemia with a mean arterial glucose concentration [G]a of 2.81 (SD ±0.40) mmol/l, the local tissuepO2 did not change significantly as compared to thepO2 values recorded during the control period with a normal [G]a of 4.51 (SD±0.70) mmol/l. During severe hypoglycemia at a [G]a of 1.39 (SD±0.2) mmol/l,pO2 began to increase continuously on all 104 measuring sites, independently of changes in arterial blood pressure and ECoG. During a period of 7–18 min of isoelectricity, tissuepO2 remained elevated so long as blood pressure did not decrease. After injection of a 25% glucose solution,pO2 gradually decreased to control values within 30–60 min in most experiments. We conclude from these results that oxygen supply is generally improved during severe hypoglycemia. We assume that the increase in tissuepO2 is mainly caused by an increase in microflow. Thus, the neuronal damage occurring after severe hypoglycemia, as reported in literature, cannot primarily be caused by an oxygen deficiency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00584262
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  • 14
    Digitale Medien
    Digitale Medien
    Use of an (n, α) nuclear reaction to study the long-distance transport of boron in trifolium repens after foliar application (1980)
    Springer
    Planta 150 (1980), S. 197-205 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Boron ; Foliar nutrition ; Nuclear reactions ; Transport (boron) ; Trifolium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The growth of white clover (Trifolium repens L.) is severely inhibited by boron starvation, but a foliar treatment with boric acid can transitorily alleviate the deficiency symptoms. The 10B(n ,α)7 Li nuclear reaction has been used to study boron transport in the plant after foliar application. More than 98% of the boron supplied remained at the point where it was applied to the leaves, and less than 2% was useful to the growth of the treated plant. This small “efficient” portion of boron was quite mobile. It was distributed to the different parts of the plant, then was transferred from the oldest parts to the newly formed leaves. Physiological and agronomical implications of these data are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00390826
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  • 15
    Digitale Medien
    Digitale Medien
    Positive two-stage carcinogenesis in female sprague-dawley rats using 7,12-dimethylbenz(a)anthracene (DMBA) as initiator and 12-o-tetradecanoylphorbol-13-acetate (TPA) as promotor (1980)
    Springer
    Virchows Archiv 385 (1980), S. 181-186 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Tumor promotion ; Tumor initiation ; DMBA ; TPA ; Two-stage carcinogenesis experiment ; Carcinogenesis ; Cocarcinogenesis ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In contrast to a previous report by Shubik, the validity of the 2-stage skin carcinogenesis experiment was demonstrated in the rat. The modified experiment was carried out in female Sprague-Dawley rats using intragastrically administered DMBA as a carcinogen and the topically applied phorbol ester TPA as a promoter. Seven groups of animals were used. Two groups were treated with TPA only, two groups were initiated only with DMBA, two further groups were both initiated and promoted, and one group served as a control. Each of the initiated/promoted groups or only initiated or promoted groups contained one sub-group in which the animals had been bilaterally ovarectomized prior to the experiment. Hyperplasia of the dorsal epidermis occurred only in the promoted and in the initiated/promoted groups. Tumors of the back skin were observed exclusively after initiation/promotion. Ovarectomy — leading to a prolonged survival time of the animals — seems to be crucial for the manifestation of malignant skin tumors. Initiation/promotion also gives rise to tumors of the forestomach, the small intestine, the liver and the colon. Tumors in other organs (especially in the mammary gland and the Zymbal gland) were also be observed after initiation alone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00427403
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  • 16
    Digitale Medien
    Digitale Medien
    Pulmonary and systemic embolism after deliberate intravenous fluorocarbon administration (1980)
    Springer
    Virchows Archiv 386 (1980), S. 331-341 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Fluorocarbon ; Extracorporeal circulation (EEC) ; Pulmonary ; systemic embolism ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary After intravenous injection of 0.1 ml Fluorocarbon (FC) into the caudal vein of rats clear droplets which are reminiscent of gas emboli appear in the pulmonary and cerebral arteries. These droplets cannot be stained with Azan, haematoxylin-eosin, Nile blue sulfate, Sudan black B, and Sudan III in Paraplast embedded or frozen sections. Gas chromatography of affected lung tissue reveals a high concentration of FC. The clear droplets are the histological correlates of FC emboli which lead to haemorrhagic lung infarction and ischaemic brain infarcts. After intralienal injection FC induces haemorrhagic infarcts of the spleen near the injection site and massive embolization of the intrahepatic portal veins with consequent liver cell necrosis. FC droplets are phagocytosed by hepatic sinusoidal lining cells. Due to the absence of a specific method for identifying FC embolization of renal vessies is difficult to assess.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00427302
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  • 17
    Digitale Medien
    Digitale Medien
    Sauvagine, a new polypeptide from Phyllomedusa sauvagei skin (1980)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 312 (1980), S. 265-270 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Phyllomedusa sauvagei ; Sauvagine ; Blood pressure ; Diuresis ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. The occurrence of sauvagine, a new polypeptide from amphibian skin, and its actions on rat blood pressure and diuresis were studied. 2. Sauvagine was found to be present in the skin of all the 10 Phyllomedusa species so far studied, amounts ranging from a few micrograms to 240 μg per g fresh skin. 3. The polypeptide displayed in the rat an intense, long-lasting hypotensive action accompanied by tachycardia. Hypotension was not modified by either atropine or propranolol, excluding the participation of the autonomic nervous system in its production. Tachycardia, on the contrary, was partially inhibited by propranolol. 4. Hypotension is probably the main cause of the intense antidiuresis seen in hydrated rats following sauvagine administration. Reduction in urina volume was accompanied by a decrease in GFR and an increase in tubular Na+ reabsorption.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00499156
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  • 18
    Digitale Medien
    Digitale Medien
    On the development of metastasizing tumors of the rat thyroid gland after combined administration of nitrosomethylurea and methylthiouracil (1980)
    Springer
    Journal of cancer research and clinical oncology 96 (1980), S. 281-285 
    Details
    ISSN: 1432-1335
    Schlagwort(e): Carcinogenesis ; Thyroid gland ; Rat ; NMU ; MTU
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Seventy-five female Wistar rats of 150 g each were given 3×40 mg/kg body weight nitrosomethylurea (NMU) and 4 weeks later until death (in the 9th–60th week) methylthiouracil (MTU), as a 0.1% solution in their drinking water. After 2 months, in the almost colloid-less thyroid gland individual foci appeared which consisted of sometimes colloid containing follicles with increased cytoplasmic and nuclear basophilia; they increased in number during the subsequent weeks and finally resulted in nodes with different morphologic structures. From the 16th week on there were tumors infiltrating the capsule, and after the 24th week there were angioinvasive carcinomas. Thirteen rats had developed lung metastasization after the 30th week. Cytology could only distinguish between the follicular carcinomas of low differentiation and the follicular adenomas. If these findings are applied to human pathology, one would have to reckon with adenomas which can develop their malignant characteristics without necessarily changing their histologic and cytologic appearance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00408100
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  • 19
    Digitale Medien
    Digitale Medien
    Stimulation-dependent changes in synaptic effects on unit activity of medial preoptic nucleus neurones in rats (1980)
    Springer
    Experimental brain research 39 (1980), S. 121-124 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Amygdala ; Medial preoptic nucleus ; Median eminence ; Rat ; Synaptic plasticity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Stimulation-dependent changes in synaptic effects were observed in medial preoptic nucleus neurones during stimulation of the amygdala or pyriform cortex in anaesthetized female rats. The changes occurred after 35–240 triple pulse stimuli repeated at 0.89 Hz. Median eminence stimulation did not produce any synaptic change. These data show the existence of synaptic plasticity in the neural pathway from the amygdala and pyriform cortex to the medial preoptic nucleus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237076
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  • 20
    Digitale Medien
    Digitale Medien
    Axonal projections and conduction properties of olfactory peduncle neurons in the rat (1980)
    Springer
    Experimental brain research 39 (1980), S. 241-248 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Olfactory peduncle neurons ; Axonal branching ; Supernormal period ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Electrophysiological methods were employed to study the axonal properties of the neurons of anterior olfactory nucleus (AON), transition zone (TZ), and rostral prepyriform cortex (RPPC) and their projections towards the ipsilateral and contralateral olfactory bulb (IOB, COB) in the rat. Of 91 antidromically driven cells, 39 (43%) and 32 (35%) responded to IOB and COB stimulation, respectively; 20 (22%) were discharged from both bulbs. Collision tests performed on the latter group indicated that these neurons have a short main axon which divides near the soma, projecting one branch to the COB and a thinner one toward the IOB. Mean conduction velocities of axons projecting to the IOB and the COB were 0.4 m/s and 0.7 m/s, respectively, the faster conducting axons having shorter refractory periods. Of the 38 neurons tested, 92% showed decreases in threshold and latency (up to 20% of control antidromic latency) after a test volley that was preceded by a conditioning pulse at intervals of 20–215 ms. Latency decreases were greater for slowly conducting axons than for the faster ones. These after-effects of impulse activity in OB afferent axons were attributed to the presence of a supernormal period of increased conduction velocity and excitability similar to that found in the olfactory nerve (Bliss and Rosenberg, 1974).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237113
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  • 21
    Digitale Medien
    Digitale Medien
    The distribution of spinal projection neurons in the hypothalamus of the rat, studied with the HRP method (1980)
    Springer
    Experimental brain research 40 (1980), S. 79-87 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Spinal tract neuron ; Hypothalamus ; HRP ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The distribution and number of hypothalamospinal tract (HST) neurons were studied following injections of horseradish peroxidase (HRP) at various levels of the rat spinal cord. The hypothalamus was divided into four areas and one nucleus, that is, the dorsal (DHA), posterior (PHA), medial (MHA) and lateral (LHA) hypothalamic areas and the paraventricular nucleus (PVN). The total numbers of HST neurons labeled with HRP varied according to the injection levels: 6,160 (C2 injections), 3,808 (T8), 1,961 (L1), 919 (L7) and 13 (S4). With C2 injections LHA contained 3,464 neurons, which accounted for 56% of the full number of HST neurons; similarly, PVN, 1,114 (18%); MHA, 865 (14%); DHA and PHA, 817 (12%). With L7 injections, LHA contained 444 labeled neurons, which accounted for 48% of the total; PVN, 327 (36%); MHA, 71 (8%); DHA with PHA, 77 (8%). As for the rostrocaudal distribution of labeled neurons, there was only a slight difference between the C2 and L6 injections in LHA, but no difference was noticed in PVN, DHA nor PHA. The present findings suggest that 70% of HST neurons may project to the cervical and thoracic cords. Although the number of labeled HST neurons decreased as the injection sites were placed caudally, no clearcut topographical arrangement was recognized in terms of the spinal projection levels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236665
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  • 22
    Digitale Medien
    Digitale Medien
    An automatic microspectrophotometric scanning method for the measurement of bone formation rates in vivo (1980)
    Springer
    Calcified tissue international 32 (1980), S. 63-68 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Rat ; Bone formation ; Fluorochrome ; Microphotometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A method for quantitative studies of the formation rate of bone has been developed. After vital staining with calcein, the fluorescence of a bone section was measured with a microphotometer controlled by a mini computer. After staining the bone structure with alizarin red S in a second step, the section was measured in transmitted light. The two data sets were combined and the shortest distances between the bone surface and the fluorescence lines were computed. With this information the distance distribution and the bone area between the label and the surface could be calculated in two different ways: with the single labeling and the continuous labeling techniques. The advantages and disadvantages of the two methods are discussed and compared with those of other techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408522
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  • 23
    Digitale Medien
    Digitale Medien
    A quantitative histologic analysis of the growing long bone metaphysis (1980)
    Springer
    Calcified tissue international 32 (1980), S. 113-122 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Rat ; Bone ; Metaphysis ; Quantitative ; Aging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The purpose of this work was to analyze the proximal tibial metaphysis of the 170 g rat in a quantitative histologic fashion which would allow some relation to tissue age to be established. Stained 3 µm thick tissue sections were analyzed with the aid of a Merz grid on an eyepiece reticule and a light microscope. Tissue mass and cell distribution were studied in all areas. The rate of change in tissue mass during aging of the metaphysis was calculated. Two regions of the metaphysis were identified. One, corresponding to the primary spongiosa, less than 4.45 days of age, is a region of high turnover of hard tissue and high numbers of osteoblasts and osteoprogenitor cells. The other, corresponding to the secondary spongiosa, is a region of relatively low net tissue turnover and low numbers of osteoblasts and osteoprogenitor cells. Osteoclasts were found relatively more uniformly distributed through the metaphysis than were osteoblasts and osteoprogenitor cells. The rate of bone formation in the primary spongiosa is 50 times that found in the Haversian bone of the rib of 5-year-old humans and about 500 times that found at the cortical-endosteal surface of ribs of 5-year-old humans. It is argued that both cell distribution and tissue distribution in the metaphysis support the concept that osteoblasts and osteoclasts, rather than osteocytes, are responsible for the maturation of the metaphysis. The inhomogeneous distribution of both cells and tissue in the metaphysis has definite meaning for the interpretation of findings concerning the incorporation of radionuclides into the skeleton.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408530
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  • 24
    Digitale Medien
    Digitale Medien
    Role of growth hormone in experimental phosphorus deprivation in the rat (1980)
    Springer
    Calcified tissue international 32 (1980), S. 105-112 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Rat ; Hypophysectomy ; Dietary phosphorus deprivation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The demands of growth are known to exacerbate the effect of phosphorus deprivation (PD). We examined whether changes associated with PD could be prevented in young rats in which growth and growth hormone (GH) were eliminated by hypophysectomy (HPX) and whether PD in normal intact rats (INT) was associated with increased secretion of GH. INT or thyroxine- and ACTH-replaced HPX rats were fed one of the three diets: 0.31% P (NP); 0.027% P (LP), and 0.31% P, pair-fed with LP-mates (NP-PF). The results indicate that HPX did not qualitatively alter several physiologic responses to PD: (a) serum and urinary phosphorus (P) decreased and urinary calcium (Ca) increased; (b) net intestinal Ca retention fell and duodenal sac uptake of45Ca rose; and (c) external P balance was restored and duodenal sac uptake of32P-phosphate increased. Only the hypercalcemia seen in INT, LP rats was prevented by HPX. In INT rats serum immunoassayable GH levels, measured in single samples, were not different between different dietary groups while pituitary bioassayable GH was reduced in both LP and NP-PF rats when compared to the NP rats. Thus, except for hypercalcemia, the physiologic responses associated with PD are not prevented by the elimination of growth and GH, and the development of these responses in INT rats was not associated with a consistent or specific alteration in GH secretion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02408529
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  • 25
    Digitale Medien
    Digitale Medien
    Studies on liver toxicants (1980)
    Springer
    Archives of toxicology 43 (1980), S. 257-262 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Bromobenzene ; Cytochrome P-450 ; Cytochrome reductase ; Glucuronyltransferase ; Lipoperoxidation ; Liver ; Mixed-function oxidase ; Peroxide ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In acute oral studies, the effect of bromobenzene on hepatic microsomal enzymes was investigated. Neither glucuronyltransferases nor cytochrome c reductase showed significant changes. Most of the mixed-function oxidases studied were inhibited with the exception of ketamine-N-demethylase. The data indicate that bromobenzene or its epoxide acts on cytochrome P-450 but not on all cytochrome P-450 species, and does not affect the reductase and the glucuronyltransferases. Microsomal lipoperoxidation and microsomal H2O2 formation were increased.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00366181
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  • 26
    Digitale Medien
    Digitale Medien
    Innervation of the liver in guinea pig and rat (1980)
    Springer
    Anatomy and embryology 160 (1980), S. 239-252 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Liver ; Innervation ; Adrenergic nerves ; Guinea pig ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The adrenergic innervation of rat and guinea pig liver is investigated using the glyoxylic-acid — paraformaldehyde method for fluorescent microscopical demonstration of adrenergic nerves and electron microscopy. The nerve distribution in the parenchyma of both animals is compared. The distribution of the liver nerves as detected with fluorescence microscopy is confirmed electron microscopically. The two species exhibit fundamental differences in their liver innervation: (1) In the guinea pig, a rich innervation is found in the trias as well as in the parenchyma. Many nerves traverse the entire liver lobules and may end near the central vein. The guinea pig hepatocyte innervation seems to be uniformly adrenergic. Electron microscopy shows that the varicosities of these nerves mostly form close contacts to the hepatocytes but also to other hepatic intralobular cells. (2) In the rat, the liver nerves are as a rule restricted to the triads, running mainly with smooth muscle containing blood vessels. It rarely happens that nerves penetrate into the lobule and come into contact with the peripherally located hepatocytes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00305105
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  • 27
    Digitale Medien
    Digitale Medien
    The ansa cervicalis and the infrahyoid muscles of the rat (1980)
    Springer
    Anatomy and embryology 159 (1980), S. 59-69 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Infrahyoid muscles ; Motoneurons ; Spinal ganglion cells ; Axons ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Perikarya of motoneurons and spinal ganglion cells attributed to infrahyoid muscle nerves of the rat were labelled by retrogradely transported horseradish peroxidase (HRP). For the differentiation of motor and sensory axons cross sections of the nerves were stained for acetylcholinesterase. Numbers and diameter distributions of perikarya and myelinated axons were determined. Motoneuronal perikarya innervating the infrahyoid muscles are located from the transition zone brain stem/spinal cord to the segment C 3. They are found mostly in the medial part of the Rexed laminae VII and VIII at the level of C 1 and C 2 and more ventrolaterally in C 3 and are therefore located to a large extent in areas until now not recognized to contain motoneurons. Our results provide evidence for a somatotopic organization of the motoneurons in the upper cervical spinal cord. The diameter distributions of motoneuronal perikarya and axons are in most cases bimodal, the two modes corresponding to α-and γ-motoneurons. In relation to the diameters of their perikarya α-axons are significantly thicker than γ-axons. In contrast to the motoneurons no clear correlation could be established between the sizes of perikarya of spinal ganglion cells and their peripheral processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00299255
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  • 28
    Digitale Medien
    Digitale Medien
    Ultrastructural study of Sertoli cells in rat seminiferous tubules during intrauterine life and the postnatal period (1980)
    Springer
    Anatomy and embryology 160 (1980), S. 11-27 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Sertoli cells ; Rat ; Fetal and postnatal life ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Sertoli cells have various functions: mechanical (creation of two compartments in the seminiferous tubules, migration of germinal cells), secretory (secretion of anti-Müllerian hormone, inhibin, androgen-binding-protein and estrogen) and phagocytic. We report an ultrastructural study of the rat Sertoli cell during maturation and consider possible correlations between the acquisition of certain morphological characteristics and certain functions. During fetal life, the Sertoli cell possesses differentiated zones of junction with the gonocytes and seems to have a role in the migration of the gonocytes towards the periphery of the seminiferous tubule. The Sertoli cell performs the phagocytosis of the gonocytes which degenerate during their migration, and seems to be the site of production of protein granules, whose presence can be related to the synthesis of anti-Müllerian hormone. After birth and before puberty, when the inclusions resembling secretory granules disappear, the Sertoli cell membranes in contact with spermatocytes II and spermatids differentiate, forming, through the differentiated junctional complexes, two compartments (adluminal and luminal) in the seminiferous tubules. Finally, they acquire the characteristics of active secretory cells, capable, in particular, of steroid synthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00315646
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  • 29
    Digitale Medien
    Digitale Medien
    Afferent neurons of the hypoglossal nerve of the rat as demonstrated by horseradish peroxidase tracing (1980)
    Springer
    Anatomy and embryology 158 (1980), S. 349-360 
    Details
    ISSN: 1432-0568
    Schlagwort(e): Afferent neurons ; Hypoglossal nerve ; Rat ; HRP-tracing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Cell bodies of sensory neurons of the rat's hypoglossal nerve were demonstrated by the somatopetal horseradish peroxidase (HRP) transport technique. Labelled perikarya were found within the second and third cervical spinal ganglia and in the vagal sensory ganglia. After application of HRP to the cut peripheral trunk of the hypoglossal nerve about 200 labelled cell bodies were counted in each animal. The vast majority of the axons from cervical spinal ganglion cells reach the hypoglossal nerve via the descending ramus (N. descendens hypoglossi). However, there may exist an additional pathway, probably via the cervical sympathetic trunk. Application of HRP to the medial and lateral end branches led to a labelling of much fewer spinal ganglion cells while the number of labelled vagal sensory neurons remained unchanged. Thus, it is suggested that the majority of the cervical afferents of the hypoglossal nerve originates within the extrinsic tongue musculature and the geniohyoid muscle, whereas the vagal afferents may perhaps derive exclusively from the intrinsic muscles. Histograms of the mean diameters of labelled cell bodies show a predominance of very small perikarya. This contrasts with the diameter distribution of sensory perikarya labelled after HRP application to nerves supplying other skeletal muscles. It is therefore assumed that the afferent component of the hypoglossal nerve is composed mainly of small-calibre axons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00301822
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  • 30
    Digitale Medien
    Digitale Medien
    Macrophages in peripheral nerves (1980)
    Springer
    Acta neuropathologica 49 (1980), S. 43-49 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Rat ; Peripheral nerve ; Macrophage ; Ultrastructure ; Histochemistry ; Acid phosphatase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The cellular content of the endoneurium in peripheral nerves of normal adult rats was studied. Endoneurial cells with high light-microscopical activity of acid phosphatase were usually located close to blood vessels or near the perineurium. Cells with the ultrastructural appearance of macrophages showed the same distribution and accounted for 2–4% of the endoneurial cell nuclei profiles. These cells rapidly endocytosed carbon particles after endoneurial administration of colloidal carbon in vitro.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692218
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  • 31
    Digitale Medien
    Digitale Medien
    Angioarchitectonics of rat cerebellar cortex during pre- and postnatal development (1980)
    Springer
    Acta neuropathologica 50 (1980), S. 131-138 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Rat ; Cerebellum ; Vessels ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The adult arrangement and the development of stem vessels and capillaries was studied in the rat cerebellum. In principle, stem vessels branch and terminate at three levels: (1) the molecular layer, (2) the Purkinje cell-granular layer, and (3) the cerebellar white matter. All stem vessels are interconnected by the capillary network which is most dense in the Purkinje cell—granular layer. As in the neocortex, the stem vessels of the cerebellum are formed successively during development, so that the later they are formed the more superficial are their terminations. The formation of multiple stem vessels in the depths of fissures and sulci during both pre- and postnatal development may correlate to regional variations in, e.g., mitotic frequency or thickness of the external granular layer. The earliest “endo-parenchymal” branches are formed before the first neurons are present. Capillary growth by sprouting during the postnatal period parallels known regional differences in the timing of the neuronal maturation, e.g., increased synaptic density and oxidative metabolism. The findings in this investigation confirm and extend the results of an earlier morphometric study on capillary development in the cerebellar cortex. Although the angiogenetic factors remain unknown, the hypothesis of a link between the vascularization and the functional maturation of the brain is corroborated by the results. Knowledge of the normal vascular development seems necessary for an understanding of brain morphogenesis and for interpretation of primary pathogenetic mechanisms in various intoxications etc.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692863
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  • 32
    Digitale Medien
    Digitale Medien
    Arrays of glycogen granules in the axoplasm of peripheral nerves at pre-ovoid stages of wallerian degeneration (1980)
    Springer
    Acta neuropathologica 50 (1980), S. 227-232 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Wallerian degeneration ; Schmidt-Lantermann incisures ; Glycogen clusters ; Peripheral nerves ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Phrenic and sciatic nerves of the rat were examined during the initial stages of Wallerian degeneration 4–48 h after axotomy about 5 mm below the level of transection. One of the first changes observed in transected axons was the appearance of glycogen granules and formation of clusters of particulate glycogen at the Schmidt-Lantermann incisures and at the nodes of Ranvier. Four hours after transection, glycogen granules were found at these sites mainly attached to the tubules of axoplasmic reticulum or dispersed in small clusters in the axoplasm. At later stages, glycogen particles increased in number and formed elongated clusters arrayed mostly longitudinally among axonal organelles filling stretches of axons about 2 μm long adjacent to the incisures and in nodal regions. The buld-up of glycogen clusters reached a peak at 22 h after axotomy, when longitudinal arrays of glycogen particles were found at about 70% of the incisures and nodes examined. The percentage of these sites containing glycogen clusters had already decreased 26 h after axotomy. When axonal degeneration advanced and axons contained only floculated material and swollen mitochondria, glycogen granules also disintegrated. It is of interest that glycogen particles accumulate in those regions of the internode where the axon will soon become disrupted during ovoid formation. The possible mechanisms leading to glycogen accumulation at these sites are discussed in relation to the active role of Schwann cells in Wallerian degeneration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688759
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  • 33
    Digitale Medien
    Digitale Medien
    The early internal vascularization of the rat brain (1980)
    Springer
    Acta neuropathologica 50 (1980), S. 221-226 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Rat ; Brain ; Vessels ; Prenatal ; Development ; Protein deprivation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The internal vascularization of the brain was studied in foetuses of normal and protein-deprived rats from embryonic day (E) 12 to 15. The position of vascular branches showed distinct relations to the various zones of the neuroepithelium. The possibility that various parts of the vascular system may differ in function, maturation, and morphogenetic relations to the neuroepithelium must be considered. The distinct vascular layers were therefore given names relating them to the respective wall zone. The ingrowth of straight stem vessels from the epiparenchymal vascular plexus into the neuroepithelium and the formation of vascular branches close to the ventricular system were referred to as stage I of the internal vascularization. The resulting plexus was called the deep vascular plexus of the ventricular zone. Its formation followed the same temporospatial gradients as the formation of the marginal zone. Following the formation of the intermediate zone, more stem vessels entered the neuroepithelium and a superficial vascular plexus of the ventricular zone was formed (stage II). This plexus was positioned close to the border between the ventricular zone and the intermediate zone. Subsequently, vascular branches also formed plexuses of the intermediate and subventricular zones (stage III). No “intraepithelial” vessels were seen on E 12. The temporospatial gradients in the telencephalic vesicles were caudal to rostral and lateral to medial, starting in the parts corresponding to the ganglionic eminence in the floor of the lateral ventricle on E 13. Only the dorsomedial angles of the hemispheres showed no vessels on E 15. No obvious differences were seen between the normal and the protein-deprived foetuses regarding the timing and extent of vascularization or the size and appearance of wall zones in the immature central nervous (I-CNS).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688758
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  • 34
    Digitale Medien
    Digitale Medien
    Fine structure of fetal rat calvarium; provisional identification of preosteoclasts (1980)
    Springer
    Calcified tissue international 31 (1980), S. 21-28 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary This is a study of the fine structure of cells of the 20-day fetal rat calvarium. Special attention is given to identifying and characterizing preosteoclasts. These cells are relatively common and located largely, but not exclusively, at the endocranial bone surface. The preosteoclasts are characterized by abundant mitochondria, an incomplete perinuclear Golgi apparatus, and variable-shaped dense granules. The dense granules are unique in appearance in that they contain an internal dense matrix surrounded by a clear halo. Most granules are circular in shape but some are elongate or tubular in form. Granules with identical appearance are observed in osteoclasts. The preosteoclasts are mononucleate, or occasionally binucleate. It is suggested that because preosteoclasts are morphologically distinctive and relatively abundant, it should be feasible to separate these cells from a heterogeneous cell isolate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02407163
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  • 35
    Digitale Medien
    Digitale Medien
    Effects of excess 1,25-dihydroxycholecalciferol in young rats (1980)
    Springer
    Archives of toxicology 43 (1980), S. 155-161 
    Details
    ISSN: 1432-0738
    Schlagwort(e): 1α,25-dihydroxycholecalciferol ; Calcification ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The oral administration for 5 days of excess 1α,25-dihydroxychole-calciferol [1,25(OH)2D3] at doses of 1, 5, and 25 μg/kg to rats, beginning at the age of 2 or 10 days, produced dose-dependent reductions in weight development and additional calcification near the skeleton. Alizarin red S stained skeleton revealed calcific deposits near the bones of the head, near the neural arches, between the ribs, along the bones both of the fore limbs and, to a lesser extent, of the hind limbs. Historically, the deposits appeared to be localized primarily in the subepithelial connective tissues. Starting treatment with 1,25(OH)2D3 (25 μg/kg for 5 days) at the age of 20 days produced additional calcification in 1 of 8 rats at only 1 location (lower jaw). Additional calcification as described above could no longer be induced by 1,25(OH)2D3 in 30-day-old rats using doses up to 25 μg/kg and 10 daily treatments. We conclude that the sensitivity of young rats to 1,25(OH)2D3-induced additional calcification, which differs in localization from that observed in adult rats, decreases with the maturation of the animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00297581
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  • 36
    Digitale Medien
    Digitale Medien
    Effect of pesticides on scheduled and unscheduled DNA synthesis of rat thymocytes and human lymphocytes (1980)
    Springer
    Archives of toxicology 45 (1980), S. 101-108 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Pesticides ; DNA repair ; Human lymphocytes ; Man ; Rat thymocytes ; Rat ; DNA synthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The action of seventeen pesticides (insecticides, fungicides and herbicides) has been studied with short-term in vitro system using rat thymocytes and/or human lymphocytes. The parameters studied were: a) the action of chemicals tested in scalar doses on DNA synthesis of rat thymocytes; b) damage exerted by pesticides on human lymphocyte DNA measured as unscheduled DNA synthesis; c) the interference of chemicals tested with human lymphocyte repair capability after damage exerted on cells by ultraviolet rays. The results obtained suggest that some of tested pesticides don't induce damages to human lymphocyte DNA, some others elicit low DNA repair if compared to the repair following a standard ultraviolet irradiation and some of them (6/17) exert a marked inhibition of cell repair processes after ultraviolet irradiation. Data are discussed on the basis of a possible role played by these substances as carcinogenic agents in the environment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01270907
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  • 37
    Digitale Medien
    Digitale Medien
    Toxic effect of various selenium compounds on the rat in the early postnatal period (1980)
    Springer
    Archives of toxicology 45 (1980), S. 207-211 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Selenate ; d,l-selenomethionine ; d,l-selenocystine ; Dimethyl selenide ; Trimethylselenonium ion ; Toxicology ; Cataract ; Ontogeny ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The toxic effect of selenium compounds (sodium selenate,d,l-selenomethionine,d,l-selenocystine, dimethyl selenide, and trimethylselenonium ion) was tested in 10-day old male rats. Increasing doses of the compounds were administered an s.c. injection and control animals were not injected. All compounds tested were lethal. Eye lens cataract was induced by the administration of selenate,d,l-selenomethionine, andd,l-selenocystine, while dimethyl selenide and trimethylselenonium ion failed to cause cataract. The cataractogenic effect of the above compounds may be attributed to their interference with glutathione metabolism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02419000
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  • 38
    Digitale Medien
    Digitale Medien
    Time-dependent accumulation of inorganic mercury in subcellular fractions of kidney, liver, and brain of rats exposed to methylmercury (1980)
    Springer
    Archives of toxicology 44 (1980), S. 231-241 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Methylmercury ; Inorganic mercury ; Rat ; Subcellular distribution ; Biotransformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Accumulation of inorganic mercury in subcellular fractions of the kidney, liver, and brain of rats was studied during 48 days after a single injection of 25 mg/kg of methylmercury chloride. The highest ratio of inorganic to total mercury was seen in the cytosol of kidney, 80% of the total being as inorganic mercury at day 48. The ratio in the mitochondria and microsomes of kidney attained a maximum level (about 50% of the total as inorganic) at day 26–37. In the liver, the ratio was strikingly low in the cytosol and microsomes as compared to the light and heavy mitochondria where about 40% of the total was present as inorganic maximally at day 26. The ratio in the brain, determined up to day 15, was very low as compared with the kidney and liver, showing less than 3% of the total in the mitochondria, microsomes, and cytosol, and 5.4% in the myelin fraction. The high accumulation of inorganic mercury in the cytosol of kidney was closely related to metallothionein-like component, while those in the mitochondria and microsomes of kidney and in the mitochondria of liver were exclusively bound to high molecular weight proteins even after deoxycholate treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00278031
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  • 39
    Digitale Medien
    Digitale Medien
    The ponto-cerebellar projection in the rat: Differential projections to sublobules of the uvula (1980)
    Springer
    Experimental brain research 38 (1980), S. 11-17 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cerebellum ; Pontine nuclei ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Microinjections of horseradish peroxidase (HRP) were made in different sublobules of the uvula (lobule IX, a, b, and c of Larsell, 1952) of the cerebellar cortex in the rat. These injections resulted in retrograde labeling of cells located in the pontine nuclei. Sublobule IXa receives a predominant input from a single column of cells situated in a dorsointermediate position in the caudal pontine nuclei. Sublobules IXb and IXc receive a pontine projection from two different columns of cells, one medial and one lateral. The location of the labeled cells in the lateral part of the caudal pons suggests a topographic projection to the subdivisions of the uvula. Sublobule IXa receives a projection from a distinct dorsointermediate region and sublobule IXb and IXc receive a projection from partially overlapping ventral regions. The cells of origin in the medial pons are organized such that more dorsally located cells project to sublobule IXc and ventrally located cells project to sublobule IXb with extensive overlap. These differential patterns of projections to the sublobules of the uvula along with other data in the literature suggest that sublobule IXa may be involved with different functional correlates than sublobules IXb and IXc.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237925
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  • 40
    Digitale Medien
    Digitale Medien
    Sequential studies on the histopathogenesis of gastric carcinoma in rats by a weak gastric carcinogen, N-propyl-N′-nitro-N-nitrosoguanidine (1980)
    Springer
    Journal of cancer research and clinical oncology 98 (1980), S. 153-163 
    Details
    ISSN: 1432-1335
    Schlagwort(e): Gastric carcinoma ; Intestinal metaplasia ; N-Propyl-N′-nitro-N-nitrosoguanidine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Sequential studies were made on the histopathologic changes in the glandular stomach of rats induced by a weak carcinogen, N-propyl-N′-nitro-N-nitrosoguanidine (PNNG). Fiftyfour rats were given 100 μg/ml of PNNG in their drinking water for 44 weeks, and then normal tap water until the end of the experiment. Rats were killed at intervals between week 1 and week 88. No marked atrophy or ulceration of the mucosa was found between week 1 and the end of the experiment. Focal intestinal metaplasia was found in week 19 and its incidence increased during the experiment. Adenocarcinoma in situ with extreme cellular atypia was found in mucosa with a normal appearance in week 67. An adenocarcinoma invading the submucosa was found in week 69, and one invading the serosa in week 88. All these pathological lesions were found on the anal side of the pyloric region. No pathologic changes were found in the fundic region. The sequential changes of the mucosa of the glandular stomach induced by this weak gastric carcinogen, PNNG, were very different from those induced by the potent gastric carcinogen, N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). Gastric carcinoma induced by PNNG seems to be more similar to human gastric cancer than that induced by MNNG.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00405959
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  • 41
    Digitale Medien
    Digitale Medien
    Postnatale Entwicklung von Rattenthrombozyten: Die Volumenverteilung und elektrophoretische Beweglichkeit von Rattenthrombozyten während des ersten Lebensmonats (1980)
    Springer
    Annals of hematology 40 (1980), S. 421-428 
    Details
    ISSN: 1432-0584
    Schlagwort(e): Rat ; Thrombocytes ; Cell volume ; Electrophoretic mobility ; Haematopoiesis ; Ratten ; Thrombozyten ; Zellvolumen ; elektrophoretische ; Beweglichkeit ; Hämatopoese
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Volumenverteilung von Rattenthrombozyten zeigt zwischen dem 5. und dem 8. Tag nach Geburt eine deutliche Zunahme im Modalvolumen. Bei rechnerischer Analyse der Kurven konnten keine deutlichen Anhaltspunkte für zwei diskrete Thrombozytenpopulationen gefunden werden. Da sich jedoch der Anstieg des Modalvolumens mit dem Beginn der Produktion einer neuen Erythrozytenpopulation deckt, und außerdem die Thrombozytenkonzentration im Blut in dieser Zeit deutlich ansteigt, können diese Veränderungen Ausdruck der Produktion einer zweiten Thrombozytenpopulation sein. Die mittlere elektrophoretische Beweglichkeit der Rattenthrombozyten fällt in den ersten drei Wochen nach Geburt nur geringfügig ab, während die der Erythrozyten im gleichen Zeitraum signifikant anstiegt.
    Notizen: Summary The volume distribution curves of rat thrombocytes show a significant rise of the modal volume between days 5 and 8 after birth. No clear evidence for two distinct thrombocyte populations was obtained by computer analysis of the volume distribution curves. However, the increase of the modal volume of the platelets correlates with the production of a new erythrocyte population. In addition, the platelet concentration in the blood increases significantly during this time. These changes could indicate the production of a second thrombocyte population. The mean electrophoretic mobility of rat thrombocytes decreases only slightly during the first 3 weeks after birth, while it increases for erythrocytes significantly during the same period.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01029684
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  • 42
    Digitale Medien
    Digitale Medien
    Glomerular tubular balance of renald-glucose transport during hyperglycemia (1980)
    Springer
    Pflügers Archiv 384 (1980), S. 39-47 
    Details
    ISSN: 1432-2013
    Schlagwort(e): d-Glucose ; Tubular Transport ; Glomerulotubular balance ; Micropuncture ; Clearance ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract d-Glucose transport in the kidney of glucose loaded rats was investigated using clearance and micropuncture techniques. The range of plasma glucose concentration in clearance experiments was 20–140 mmol·l−1 and in micropuncture experiments 17–94 mmol·l−1. 1. During hyperglycemia, the glucose concentration in endproximal tubular fluid was elevated above that in arterial plasma. At plasma concentrations above 60 mmol l−1 intratubular glucose concentration was found to be about 1.2 times higher than in plasma. 2. At endproximal puncture sites TF/Posmol was unity throughout the investigated range of hyperglycemia. 3. Proximal tubular glucose reabsorption during hyperglycemia is close to saturation which is compatible to aK m=10.8 mmol l−1 as determined previously. 4. Passive glucose permeability does not change during hyperglycemia. The permeability constant of 2.03·10−5 cm·s−1 does not differ significantly from that during normoglycemia, 1.9·10−5 cm·s−1. 5. Single nephron glomerular filtration rate (SNGFR) and fluid reabsorption in the proximal convolution (C) were significantly correlated during hyperglycemia (r=0.78,P〈0.001). Fractional volume reabsorption during hyperglycemia was decreased to 0.36 as compared to control, but during hyperglycemia it was not affected by the magnitude of the glucose plasma concentration. 6. During hyperglycemia, proximal tubular glucose reabsorption (TG) was correlated to SNGFR (r=0.64,P〈0.001). This relation became insignificant when the influence of volume reabsorption (C) is controlled for (r=0.17,P〉0.5). However, the significance of the correlation between TG and C persists when the influence of SNGFR is held constant. 7. Calculations indicate that when glucose reabsorption was doubled, et sodium transport was increased about fourfold. 8. In hyperglycemia, renal transport rate (TG), when factored by renal glomerular filtration rate (GFR) seems to be linearly related to glucose plasma concentration. Up to endproximal puncture site 25.5% and by the entire kidney 68.2% of the tubular glucose load were reabsorbed. The difference may be attributed either to glucose transport systems which are localized distal to the proximal convoluted tubules and/or to an inhomogenity of the glucose transport in the different types of nephrons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00589512
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  • 43
    Digitale Medien
    Digitale Medien
    Acid base status in unanesthetized, unrestrained guinea pigs (1980)
    Springer
    Pflügers Archiv 384 (1980), S. 93-97 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Guinea pig ; Rat ; Anesthesia ; Chronic cannulation ; Blood acid-base status
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Acid-base status of arterial blood was measured in chronically cannulated, unanesthetized, unrestrained guinea pigs. Normal values were: pH=7.444±0.032,PaCO2=35.7±4.4; HCO 3 − =24.4±2.8; BE=+0.4±2.1 (n=69) andPaO2=91.9±7.3 (n=25) (Values are mean±S.D.). Induction of light anesthesia with thiopentone caused a respiratory depression (decrease inPaO2) accompanied by respiratory acidosis (increase inPaCO2 and decrease in pH) and a development of slight metabolic acidosis (decrease in base excess and standard bicarbonate). Acid base parameters of guinea pigs are compared to those obtained from rats under identical experimental conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00589520
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  • 44
    Digitale Medien
    Digitale Medien
    Effect of feeding a high protein diet on solute-coupled water absorption from rat colon (1980)
    Springer
    Pflügers Archiv 388 (1980), S. 165-168 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Colon ; Water absorption ; Electrolyte absorption ; High protein diet ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Using an in vivo sac technique, net transport of water, Na, Cl and K was studied in the colon ascendens of rats fed either a high carbohydrate (HC) or high protein (HP) diet, since water intake is elevated in HP-rats. The ligated colon sacs were filled with isotonic Krebs-Henseleit solution. Net Na and Cl absorption rates related to 1 g intestinal dry weight were 46% and 30% higher in HP-rats compared with HC-rats. Net water absorption in HP-rats exceeded that in HC-rats by 115%. Therefore the ratio between net water absorption and net absorption of solutes was higher in HP-rats than in HC-rats, and thus the hypertonicity of the absorbate was lower in the HP-rats. There was a net secretion of K in both groups of rats to about the same extent. Experiments with22Na indicate that the increased net Na absorption in HP-rats was due to an increased unidirectional Na transport from the lumen to the blood side of the colon. The group difference in the ratio between net absorption of water and solutes might be a manifestation of regulatory mechanism controlling intestinal water absorption.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00584123
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  • 45
    Digitale Medien
    Digitale Medien
    Organ of Corti-specific polypeptides: OCP-I and OCP-II (1980)
    Springer
    European archives of oto-rhino-laryngology and head & neck 226 (1980), S. 123-128 
    Details
    ISSN: 1434-4726
    Schlagwort(e): Organ of Corti ; Organ-specific polypeptides ; Two-dimensional polyacrylamide gel electrophoresis ; Guinea pig ; Rat ; Actin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Two polypeptides, OCP-I and OCP-II, specific to the organ of Corti of the guinea pig and the rat, were detected by two-dimensional polyacrylamide gel electrophoresis. They were neither present in other inner ear structures, nor in other organs tested. The two polypeptides constitute a substantial portion of the total protein of the organ of Corti. Both inner and outer layer of the organ of Corti contained approximately equal amounts of OCP-I and OCP-II. The molecular weights of OCP-I and OCP-II are 37,000 and 22,500 daltons, respectively. The corresponding pI values are 4.9 and 5.1, respectively. In addition, actin and tubulin were detected in both layers of the organ of Corti.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00455126
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  • 46
    Digitale Medien
    Digitale Medien
    Mesenterico-caval shunt in rats (1980)
    Springer
    Research in experimental medicine 177 (1980), S. 79-84 
    Details
    ISSN: 1433-8580
    Schlagwort(e): Mesenterico-caval shunt ; Microsurgical procedure ; Patency rate ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A microsurgical technique for mesenterico-caval shunting in the rat is described. The method results in a portal blood drainage from the upper abdominal contents whereas the blood of the mesenteric vein is shunted to the inferior caval vein. Controls were undertaken after 1 and 3 weeks, either visually or radiologically. Twenty-two of 26 surviving animals showed patency of the shunt. All animals had undisturbed blood supply to the portal stump.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01851635
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  • 47
    Digitale Medien
    Digitale Medien
    Hypothalamic lesions in rats with long-term streptozotocin-induced diabetes mellitus (1980)
    Springer
    Acta neuropathologica 52 (1980), S. 119-127 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Hypothalmus ; Rat ; Streptozotocin ; Diabetes ; Morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Sixteen male Wistar rats, 1 year after injection of streptozotocin or vehicle, were fixed by whole-body perfusion, the brains were removed and processed for light and electron microscopy. Study of semithin sections from the hypothalamic area revealed changes in the arcuate nucleus and median eminence. The lesions, in comparison with controls, were subjected to a blind semiquantitative evaluation. The following changes were observed by light microscopy in diabetic rats: accumulation of glycogen (P〈0.01), degeneration of neurons (P〈0.05), hypotrophy of tanycytes (P〈0.01), and axonal changes. Electron microscopy of diabetic rats revealed that glycogen was increased in neuronal bodies and processes (axons, synapses), also in tanycytes, and glia cells. In neurons were seen: dilated and fragmented endoplasmic reticulum, degranulated ergastoplasm, loss of organelles, increased number of microtubuli, myelin figures, irregulatities in the form of nuclei, and appearance of chromatin. The tanycytes in diabetic animals were reduced in volume, had an increased nuclear cytoplasmic ratio, a reduced number of organelles, short basal processes, and almost complete loss of the apical processes. These changes demonstrate the existance, under experimental conditions, of an encephalopathy pathogenetically related to streptozotocin-induced diabetes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00688009
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  • 48
    Digitale Medien
    Digitale Medien
    Effects of several lipidosis-inducing drugs upon the area postrema and adjacent medullary nuclei of adult rats (1980)
    Springer
    Acta neuropathologica 52 (1980), S. 179-187 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Medulla oblongata ; Rat ; Chlorophentermine ; Chloroquine ; Lipidosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The present study is concerned with the question of whether or not amphiphilic drugs (chloroquine, quinacrine, perhexiline) that fail to induce general lipidosis in the central nervous system (CNS) of adult rats can produce lipidosis in a circumventricular organ (area postrema) not furnished with a blood-brain barrier. Chlorphentermine known to induce general lipidosis in CNS of adult rats served as reference compound. All drugs, when chronically applied in high oral doses, induced significant perikaryal lipidosis in the area postrema. In the adjacent nuclei (nucleus tractus solitarii, nucleus dorsalis nervi vagi, nucleus nervi hypoglossi, nucleus gracilis), only chlorphentermine caused generalized lipidosis, whereas the other drugs had either limited or no effects. The present findings strongly suggest that the exemption, of most regions of the CNS of adult rats, from lipidosis induced by chloroquine and others is due to hindered drug distribution across the blood-brain barrier, rather than being due to non-susceptibility of central neurons toward the lipidosis-inducing action of the drugs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00705806
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  • 49
    Digitale Medien
    Digitale Medien
    Cytometric investigations in histochemically identified neurons — Changes of fluorescence intensities and nuclear diameters in dopamine neurons of the arcuate nucleus in the cycling rat (1980)
    Springer
    Experimental brain research 38 (1980), S. 293-298 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Rat ; Estrous cycle ; Hypothalamic arcuate nucleus ; Dopamine perikarya ; Cytometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The relative formaldehyde-induced fluorescence intensities and the diameter of cell nuclei of fluorescent perikarya of the arcuate nucleus were recorded in serial cross-sectioned hypothalamic arcuate nuclei of regularly cycling rats (5 estrous and 4 proestrous animals). Stress-induced changes of cytometric parameters were avoided by preadaptation of animals to handling procedures. Dopamine neurons in a 75 μm thick periventricular layer of the arcuate nucleus exhibited significantly smaller nerve cell nuclei and significantly reduced relative fluorescence intensities in proestrous rats. Both of these cytometric parameters indicate a decrease in the activity of periventricular dopamine neurons of the arcuate nucleus. The reported findings might support the hypothesis that dopamine inhibits the release of LH-RH.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236648
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  • 50
    Digitale Medien
    Digitale Medien
    Swimming in the rat: Analysis of locomotor performance in comparison to stepping (1980)
    Springer
    Experimental brain research 40 (1980), S. 374-382 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Cinematography ; Electromyography ; Locomotion ; Rat ; Swimming
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Swimming in a mammalian quadruped, the rat, is analyzed in kinematic (joint angles) and electromyographic (EMG) terms. Data were collected on the movements of the hip, knee, ankle, and toe joints and three principle extensors and three flexors of the right hindlimb and compared with similar data collected on the same rats during treadmill stepping. The flexion, or protraction phase of swimming and stepping had many elements in common, including a similarity of EMG activity patterns and corresponding limb movements. However, in the extension, or retraction phase, there were notable differences. Although joint-extensor muscles were all coactive in both conditions, the brevity of the swimming extensor phase precluded the characteristic variation in EMG activity levels seen in the extensors in stepping. The flexors, in particular semitendinosus (ST), exhibited bursts of activity at the end of the extensor phase of swimming which were not present during the comparable period of stepping. The extra burst in ST produced a very rapid knee flexion at this time. Whereas the range of hip joint movement was similar in the two conditions, the ranges of the knee and ankle joints were expanded during swimming. Overall, the evidence suggests that swimming is a very rapid form of a basic locomotor pattern in which the extensors are driven to their maximum contraction rate. The extra extension of the limb derives from the absence of ground reaction forces, allowing the knee and ankle joints to fully extend. The added bursts in the flexors remain to be explained. A discussion of these results in terms of current theories of single limb locomotor pattern generation is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236146
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  • 51
    Digitale Medien
    Digitale Medien
    Enhanced suppression of a conditioned avoidance response by haloperidol but not phenoxybenzamine in rats with bilateral parafascicular lesions (1980)
    Springer
    Experimental brain research 40 (1980), S. 164-169 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Rat ; Avoidance conditioning ; Parafascicular nucleus ; Dopamine ; Noradrenaline
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Male rats were subject to bilateral lesions in the parafascicular nucleus (PF) of the thalamus. The lesions had little or no effect on the performance of a pre-operatively acquired conditioned avoidance response. However, the PF lesioned animals displayed an enhanced response to the dopamine receptor blocking agents haloperidol or pimozide but not to the noradrenaline receptor blocking agent phenoxybenzamine. The results indicate that intralaminar thalamic nuclei and dopaminergic extrapyramidal motor pathways are functionally connected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237534
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  • 52
    Digitale Medien
    Digitale Medien
    A technique for in vivo and in vitro studies on the preserved and transplanted rat kidney (1980)
    Springer
    Urological research 8 (1980), S. 107-112 
    Details
    ISSN: 1434-0879
    Schlagwort(e): Kidney transplantation ; Rat ; Renal ischaemia ; Renal preservation ; Microsurgical technique
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A modified technique for preservation and transplantation of rat kidneys, allowing precise control of the periods of warm and cold ischaemia, is presented. The donor kidney is placed in a continuously cooled micropuncture cup during the insertion. End-to-end anastomosis of arteries and veins is performed. The technique causes negligible circulatory changes on restoration of the blood flow. Eighty-nine consecutive transplantations are analysed. Complications from the vascular anastomoses occurred in 6% (5/89). In 53 survival experiments complications from the ureteric anastomoses occurred in 9% (5/53). The methodological scatter was small, with a distinct difference in the serum creatinine course and mortality of recipients obtaining kidneys subjected to cold is chaemia for different lengths of time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00271437
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  • 53
    Digitale Medien
    Digitale Medien
    Ventilatory CO2 response in endurance-trained rats (1980)
    Springer
    European journal of applied physiology 45 (1980), S. 103-108 
    Details
    ISSN: 1439-6327
    Schlagwort(e): Endurance training ; CO2 response ; Ventilation ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A CO2 rebreathing technique was used to assess possible changes in the ventilatory response to CO2 in rats following a 14-week swim training program. Over the final 9 weeks, the rats swam 1 h per day with a weight of 2.5% of the body weight attached to the tail. Ventilation was measured by a barometric method in awake, restrained rats in a total body plethysmograph at CO2 concentrations of 0, 2, 4, 6, and 8%, with an initial O2 concentration of approximately 100%. Ventilation increased in the trained rats with increasing CO2 from 775 ml·min−1·kg−1 at 0% CO2 to 1,387 ml·min−1·kg−1 at 8% CO2. This increase was a consequence of a 34% increase in tidal volume and a 32% increase in breathing frequency. In comparison with a group of sedentary control rats, there was a significantly higher ventilation and tidal volume at 0% CO2; however, this difference disappeared with increasing levels of CO2. A significantly lower resting heart rate was observed in the exercised (296±44 beats·min−1, mean±SD) compared to the sedentary control rats (380±42). It was concluded that, while the normal training response of resting bradycardia was observed following this duration and intensity of training, endurance swimming had no significant effect on the ventilatory response to CO2 in the rat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00421317
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  • 54
    Digitale Medien
    Digitale Medien
    The post-exercise recovery of triglycerides in rat tissues (1980)
    Springer
    European journal of applied physiology 45 (1980), S. 33-41 
    Details
    ISSN: 1439-6327
    Schlagwort(e): Post-exercise recovery ; Triglycerides ; Glycogen ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Triglycerides (TG) recovery after exhaustive muscular exertion was investigated in tissues of fed rats and rats fasted for 24 h before exercise. In both groups the exercise caused reduction of TG level in the fast-twitch-oxidative-glycolytic (FOG) muscle, in heart muscle, and in plasma and accumulation of TG in liver. In the fed group the level of TG in FOG muscle, in liver, and in plasma normalized after 1 h of recovery, but only after 3 h in heart muscle. Treatment with glucose somewhat slowed down this process in FOG muscle. In the fasted group, the level of TG in each tissue returned to the pre-exercise value after 3 h of recovery.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00421199
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  • 55
    Digitale Medien
    Digitale Medien
    Masthead (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980) 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010101
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  • 56
    Digitale Medien
    Digitale Medien
    Control by calcium of the contractility of Labyrinthula slimeways and of the translocation of Labyrinthula cells (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 17-29 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Ca-ion ; Labyrinthula ; contraction ; glycerination ; Ca-reservoir ; cell movement ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Colonies of Labyrinthula, a colonial marine protist, expand by protrusive movements of the specialized slimeways. The movements recorded in time-lapse films are of two types - filopodial and lamellipodial - and occur at rates equivalent to those of cell translocation.Evidence is presented that Ca2+ regulates the contraction of the actomyosin system of filaments present in the slimeways of Labyrinthula. In glycerinated models or in colonies exposed to ionophore A23187 contraction is evidenced by the occurrence of periodic contractions of the slimeways, giving them the appearance of strings of beads. Glycerinated slimeways contract on the addition of Ca2+ and ATP while slimeways provided with ionophore A23187 contract on addition of Ca2+ alone. The concentration required is 1.1 × 10-7 M Ca2+ while concentrations of 6.2 × 10-8 or lower were ineffective. Rates of contraction were measured in time-lapse films which provide evidence that contractions and beading occur everywhere in the slimeway system. When beading occurs, the 6-nm filaments transform from an array of parallel single filaments into an interwoven meshwork.We have identified by pyroantimonate-OsO4 fixation, as possible Ca2+ reservoirs, deposits of Ca2+ in bothrosomes - structures through which cell secretions pass into the slimeways. The electron-dense deposits are located at the base of the bothrosome and disappear after incubation with EGTA. We propose that the translocation of cells as well as the movements of slimeways may be regulated by the cells through the local measured liberation of Ca2+ from the bothrosome where it is sequestered.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010103
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  • 57
    Digitale Medien
    Digitale Medien
    Tubulin nucleation and assembly in mitotic cells: Evidence for nucleic acids in kinetochores and centrosomes (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 1-15 
    Details
    ISSN: 0886-1544
    Schlagwort(e): centrosomes ; kinetochores ; microtubule initiation ; nuclease enzymes ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A lysed cell system was used to study the organelle structure and nucleation of exogenous tubulin at kinetochores and centrosomes in mitotic PtK2 cells. We have used this lysed cell system in conjunction with nuclease digestion experiments to determine which specific nucleic acids (DNA or RNA) are involved in either the structure and/or microtubule-initiating capacity of kinetochores and centrosomes. The results indicate that DNase I specifically decondenses the kinetochore plate structure, with the eventual loss in the ability of the chromosomes to nucleate microtubule assembly. DNase I had no effect on either the structure or nucleating capacity of centrosomes. Both RNase T1 and RNase A specifically attacked the amorphous pericentriolar material of the centrosomes, with a concomitant loss in the ability of this material to nucleate microtubule formation. Neither RNase appeared to affect the structure or nucleating capacity of the kinetochore. Therefore, the two types of nucleases appear to exert preferential effects on the different types of microtubule initiation sites in mitotic mammalian cells. The results suggest that DNA is a major component of the kinetochore, while RNA is a major component of the amorphous pericentriolar material. These findings support the concept that microtubule initiation sites in mitotic cells contain nucleic acids which are essential for the structural and functional integrity of the sites.
    Zusätzliches Material: 45 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010102
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  • 58
    Digitale Medien
    Digitale Medien
    Redistribution of actin and fascin in sea urchin eggs after fertilization (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 31-40 
    Details
    ISSN: 0886-1544
    Schlagwort(e): actin ; fascin ; actin cross-linking proteins ; fertilization ; microvilli ; sea urchin eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Following fertilization, the sea urchin egg cortex undergoes a structural change involving the assembly and organization of actin filaments into microvilli. Antifascin localizes this actin cross-linking protein in the microvilli of the fertilized egg cortex but no organized staining is present in the unfertilized cortex. Determination of the actin content of eggs using the DNAase I inhibition assay indicates that actin is about 1.4% of the total protein. Approximately 90% of this actin is soluble in low calcium isotonic extracts of unfertilized eggs while only 60-65% can be recovered in identical extracts of fertilized eggs. Similar measurements for fascin using a radioimmunoassay indicate this molecule represents about 0.3% of the total egg protein, essentially all of which is recovered in low calcium isotonic extracts of unfertilized eggs. After fertilization only 65-70% of this actin cross-linking protein is in the soluble phase. These results demonstrate a markedly different solubility for actin and fascin after fertilization, when the indirect immunofluorescence staining localizes fascin in the microvilli, and are consistent with the idea that fascin organizes newly polymerized actin filaments into the microvillar cores. A consideration of the amounts of actin and fascin incorporated into the cortex after fertilization and the number of microvilli on the egg surface indicates that the measured values are sufficient to account for the observed microvillar elongation.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010104
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  • 59
    Digitale Medien
    Digitale Medien
    Physarum myosin light chain binds calcium (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 63-71 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Physarum polycephalum ; myosin light chains ; polyacrylamide gel electrophoresis ; calcium ; cytoplasmic streaming ; actomyosin ATPase regulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Myosin from the slime mold Physarum polycephalum contains three sizes of polypeptides: a heavy chain and two light chains, LC-1 and LC-2. Using a simple qualitative test for calcium binding by comparing electrophoretic migration of the polypeptides in sodium dodecy1 sulfate (SDS) acrylamide gels in the presence and absence of calcium, we have found that Physarum myosin light chain LC-2 migrates with an apparent molecular weight of 16,900 daltons in the presence of the metal ion chelator ethylene glycol bis (B-aminoethyl ether) N,N′-tetraacetic acid (EGTA). However, if calcium chloride is added to the sample prior to electrophoresis, the apparent molecular weight decreases to 16,100. Lanthanide and cadmium ions, but not magnesium, can substitute for calcium. Because the ionic radii of Ca2+, La3+, and Cd2+ are almost identical, we conclude that Physarum myosin LC-2 possesses a very size-specific binding site for calcium. Physarum myosin LC-1 and the heavy chain give no evidence for binding calcium by this test. Since cytoplasmic streaming in the plasmodium of Physarum requires calcium, our evidence indicates that the calcium-binding property of Physarum myosin LC-2 may be important in regulating the production of force by actomyosin in the ectoplasm. Unexpectedly, the myosin light chain in Physarum capable of binding calcium, LC-2, is the essential light chain, while LC-1 is a member of the regulatory class of myosin light chains [V. T. Nachmias, personal communication]. Until now, essential myosin light chains have not been shown to have high affinity divalent cation binding sites. This means a new version of the myosin-based model for actomyosin regulation by calcium may be required to explain cytoplasmic movement in Physarum, and perhaps in other motile systems involving cytoplasmic myosins as well.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010106
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  • 60
    Digitale Medien
    Digitale Medien
    The role of the extracellular matrix in cell motility in fibroblast aggregates (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 99-112 
    Details
    ISSN: 0886-1544
    Schlagwort(e): cell motility ; extracellular matrix ; collagen ; glycosaminogly cans ; collagenase ; hyaluronidase ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The effect of specific components of the extracellular matrix on the motility of tissue cells was studied using organ-cultured aggregates of embryonic fibroblasts. Spherical aggregates of chick embryo heart and skin fibroblasts were fused with [3H]-thymidine-labeled aggregates of the identical cell type. The movement of labeled cells into the unlabeled partner aggregate served as an estimate of cell motility in the cultured tissue-like aggregates. Collagenase treatment decreased the collagen content of heart fibroblast aggregates and increased cell motility; ascorbic acid treatment increased the collagen content of skin fibroblast aggregates and decreased cell motility. Reduction of the glycosaminoglycan content with testicular hyaluronidase had no measurable effect on cell motility in heart fibroblast aggregates.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010108
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  • 61
    Digitale Medien
    Digitale Medien
    Tubulin content and synthesis in differentiating drosophila cells in culture (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 113-129 
    Details
    ISSN: 0886-1544
    Schlagwort(e): tubulin ; Drosophila ; β-ecdysterne ; differentiating ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Drosophila Kc cells exposed to physiological doses of the moulting hormone, β-ecdysone, elongate, become motile, and subsequently aggregate. This pattern of morphogenesis was found to require the assembly of a microtubular cytoskeleton. Tubulin content was significantly increased in hormone-treated cells when compared to controls, as measured by a 3H-colchicine-binding assay. However, determinations of rates of tubulin synthesis and breakdown revealed no difference between control and hormone-treated cells for either parameter. When tubulin content was assayed by methods that do not depend on colchicine-binding activity, no difference between hormone-treated and control cells was observed. These results are discussed in terms of a model in which β-ecdysone affects the distribution of tubulin in “assembly-active” and “assembly-inactive” pools.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010109
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  • 62
    Digitale Medien
    Digitale Medien
    Identification of genetic elements associated with muscle structure in the nematode caenorhabditis elegans (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 73-97 
    Details
    ISSN: 0886-1544
    Schlagwort(e): nematodes ; muscle structure ; mutants ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A search for new mutants with altered body-wall muscle cell structure has been undertaken in the nematode C elegans. One-hundred seventeen mutants were isolated after mutagenesis with ethyl methanesulfonate or ultraviolet light, enrichment by a motility-requiring test, and screening by polarized light microscopy; 102 of these mutants were in ten previously established genes, whereas 15 mutants permitted the identification of seven new complementation groups in C elegans. Two of the new genes map on linkage group I (unc-94 and unc-95) and four genes are sex linked (unc-96, unc-97, unc-98, and unc-99). One complementation group (unc-100) could not be mapped because of the special characteristics of its cohort mutants. Representative mutants of the mapped genes were examined by polarized light and electron microscopy. All of the mutants exhibit disruptions of the normal A and I band organization of thick and thin filaments. Several of the mutants produce collections of thin filament-like structures. In one of these cases, HE177 demonstrated collections of somewhat wider, intermediate-sized filaments as well, and the HE195 mutant produces paracrystalline aggregates of thin filaments amidst looser arrangements of similar structures. The mutants in newly identified genes, as well as the new mutants in previously established genetic loci, have promise as tools in the study of myofibrillar assembly and function. Among the 22 complementation groups associated with body-wall structure in C elegans, it is likely that some genes code for regulatory and morphogenetic functions in addition to the well-studied structural, contractile, and calcium-associated proteins in muscle.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010107
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  • 63
    Digitale Medien
    Digitale Medien
    An analysis of spindle ultrastructure during anaphase of micronuclear division in Tetrahymena (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 41-61 
    Details
    ISSN: 0886-1544
    Schlagwort(e): mitosis ; mitotic spindle ; kinetochore ; microtubule ; micronucleus ; Tetrahymena ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Mitotic micronuclei were isolated from Tetrahymena thermophila and data on spindle ultrastructure were obtained from serial, transverse sections. Comparison of data from nuclei at meta- and early anaphase with data from nuclei at late anaphase showed that during anaphase, sister kinetochores move from the equator to the spindle poles, but kinetochore translocation occurs without any apparent change in either the number or length of kinetochore microtubules. This unprecedented result is ascribed significance with regard to the mechanism of kinetochore transport since there are only a limited number of ways that result could be achieved. The organization of the peripheral sheath changes during anaphase as evidenced by gaps in the sheath at late anaphase. Numerous kinetochore and non-kinetochore microtubules are located in polar regions of the spindle at late anaphase, whereas those regions contained only peripherally arranged microtubules at earlier stages. Tracking of individual kinetochore microtubules in late anaphase nuclei showed that some of them appeared to become incorporated into the peripheral sheath near the pole. At early and late anaphase, crossbridges connect adjacent microtubules throughout the spindle poleward to the kinetochores, as well as in the interzone.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010105
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  • 64
    Digitale Medien
    Digitale Medien
    Meeting report (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 159-162 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010112
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  • 65
    Digitale Medien
    Digitale Medien
    Invited review: Guidance cue patterns and cell migration in muiticeliuiar organisms (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 141-157 
    Details
    ISSN: 0886-1544
    Schlagwort(e): axon guidance ; chemotaxis ; haptotaxis substrate pathways ; development ; pattern biology ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In multicellular organisms, guidance cues are either diffusible molecules or cellular or extracellular surfaces that are found in reproducible locations and that orient migrating cells and cell processes. The pattern of the guidance cues usually determines the complex in vivo migration routes of motile cells and cell processes. Within organisms, guidance cues are found to be organized in two general patterns: (a) broad gradients - such as diffuse chemotactic gradients; (b) discrete routes (substrate pathways) - such as chemotactic gradients confined to long channels, and such as the axon surface which represents a long specific highway for migrating Schwann cells.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010111
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  • 66
    Digitale Medien
    Digitale Medien
    Announcement (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 163-163 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010113
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  • 67
    Digitale Medien
    Digitale Medien
    The formation and elongation of filopodia during transformation of sea urchin coelomocytes (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 131-140 
    Details
    ISSN: 0886-1544
    Schlagwort(e): sea urchin coelomocytes ; motility ; filopodial formation and elongation ; ciné film analysis ; scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Sea urchin coelomocytes were examined during their morphological transformation from petaloid to filopodial forms by scanning electron microscopy and ciné film analysis. Petaloid coelomocytes have a variable morphology but, in general, consist of numerous thin sheets of cytoplasm, the petals, arranged in three dimensions around a central nuclear region. The transition to the filopodial form can occur in either substrate-attached or suspended cells and begins with the formation of several microspikes at the edge of each petal. These become more apparent as the cytoplasm between each microspike/filopodium is retracted centripetally. Concomitantly, the diameter of the flattened cell is increased by as much as twofold as the filopodia actively lengthen at a uniform, average rate of 0.5 μm/minute. The transformation process requires ca 15 minutes and is complete when the cell diameter no longer increases. These filopodia are functionally distinct from the passively produced retraction fibers observed in cultured mammalian cells. The formation of filopodia is biphasic and includes both a cytoplasmic retraction phase and an active extension phase.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010110
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  • 68
    Digitale Medien
    Digitale Medien
    Statement of purpose (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 167-167 
    Details
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010114
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  • 69
    Digitale Medien
    Digitale Medien
    A peculiar fibrillar pattern in the myocardial cells of trabeculae carneae in the right ventricle of the rat, mouse, and rabbit (1980)
    Springer
    Cell & tissue research 208 (1980), S. 165-168 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Cardiac muscle cells ; Trabeculae carneae ; Fibrillar pattern ; Mouse ; Rat ; Rabbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cardiac muscle fibers in the trabeculae carneae of mice, rats, and rabbits show a special arrangement of densely interwoven myofibrils. They cross at various angles; however, a preferred orientation of the fibrils cannot be discerned. It is suggested that due to this arrangement the myocytes of trabeculae are not able to contract to the same extent as ventricular myocytes, but thereby gain a high rigidity during contraction. Hence, they may play a principal role as “guiding ridges” for the flow of blood, thereby improving hemodynamics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234181
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  • 70
    Digitale Medien
    Digitale Medien
    Scanning electron microscopy of the cleft of the rat pituitary (1980)
    Springer
    Cell & tissue research 206 (1980), S. 139-143 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pituitary cleft ; Scanning electron microscopy ; Cell surface changes ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Scanning electron microscopy of the lining of the pituitary cleft was carried out in normal, lactating, castrated, adrenalectomized, and cyproterone-treated adult rats. Four cell types could be differentiated in the posterior wall in control and experimental animals: (1) cells with a smooth surface, (2) cells with microvilli located at the cellular borders, (3) ciliated cells, and (4) cells with evenly distributed microvilli. The anterior wall showed mainly cells with few microvilli located at their margins, and clusters of ciliated cells. In normal, and more frequently in experimental animals, the anterior wall showed shriveled cells, and variously sized cavities. Colloid appeared either as a network of finely granular material or as compact bodies adhering to the epithelial surface. These observations suggest that a compact component of the colloid is derived at least in part from degraded cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233614
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  • 71
    Digitale Medien
    Digitale Medien
    Immunohistochemical study of the LHRH-synthesizing neuron system of aged female rats (1980)
    Springer
    Cell & tissue research 209 (1980), S. 499-503 
    Details
    ISSN: 1432-0878
    Schlagwort(e): LHRH perikarya ; Aging ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The LHRH-synthesizing neuron system was studied in young proestrous and old female rats, and in aged ovariectomized or reserpine-treated females. The medial preoptic area and septal region of old animals contains more LHRH positive perikarya compared to that of young proestrous rats. Reserpine treatment moderately increases the number of immunostainable LHRH cells, while ovariectomy is ineffective in this respect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234761
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  • 72
    Digitale Medien
    Digitale Medien
    Luliberin and somatostatin fiber-terminals in the subfornical organ of the rat (1980)
    Springer
    Cell & tissue research 210 (1980), S. 33-45 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Luliberin (LRF)-terminals ; Somatostatin-terminals ; Subfornical organ ; Neurohemal regions ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary With the aid of light- and electron- microscopic immunocytochemistry, somatostatin- and luliberin (LRF)-positive fibers can be demonstrated in the rat subfornical organ (SFO). Each of the neurohormones has a specific location: LRF in the lateral parts of the organ, and somatostatin in the center of the posterior zone. Common to both neurohormone-containing fibers is the pattern in which they reach the organ as well as the fact that their terminals are located in the perivascular spaces of fenestrated vessels, i.e., within the limited neurohemal regions of the organ. Since injection of India ink of different colors demonstrates that the capillary bed of the SFO is connected with the central capillaries of the choroid plexus, the question arises as to whether the neurohormones released in the area of the SFO influence the choroid plexus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232139
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  • 73
    Digitale Medien
    Digitale Medien
    Investigations on the turnover of adrenocortical mitochondria (1980)
    Springer
    Cell & tissue research 210 (1980), S. 333-337 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Zona glomerulosa ; Angiotensin II ; Mitochondria ; Stereology ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effects of a chronic treatment with angiotensin II (up to 15 consecutive days) on the mitochondria of the rat zona glomerulosa cells were investigated by electron microscopic and stereological methods. Angiotensin induced a significant increase in the volume of the mitochondrial compartment. Up to the 3rd day of treatment this was due only to the hypertrophy of the organelles, and from the 3rd to the 15th day exclusively to mitochondrial proliferation. The hypothesis that angiotensin controls the growth and proliferation of rat zona glomerulosa mitochondria is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237620
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  • 74
    Digitale Medien
    Digitale Medien
    The adsorptive and transport capacity of tanycytes during the perinatal period of the rat (1980)
    Springer
    Cell & tissue research 211 (1980), S. 493-501 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamo-hypophysial system ; Rat ; Tanycytes ; Transport ; Ontogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Transport of ferritin and horseradish peroxidase from the 3rd ventricle to the median eminence was examined in rats during the perinatal life, the time when functional interrelations between hypothalamus and hypophysis are established. Protein tracers injected into the lateral ventricle are adsorbed on the apical surface of the tanycyte, mainly on its protrusions or in indentations. On the 18th day of prenatal life a few small bleblike protrusions are observed. After birth microvilli appear. In time their concentration increases to result in an increase of adsorbed substances. They are taken up by smooth and coated pinocytotic vesicles and transported to the basal portion of the cell or to the intercellular space bypassing junctional complexes. In addition to pinocytotic vesicles protein tracers fill channels of smooth ER or Golgi complex and multivesicular bodies illustrating a process probably involved in metabolic or secretory processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234403
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  • 75
    Digitale Medien
    Digitale Medien
    Localization and neurophysiological properties of motoneurones of the M. triceps surae of the rat after retrograde labelling with evans blue (1980)
    Springer
    Cell & tissue research 212 (1980), S. 73-81 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Motoneurones ; Triceps surae muscle ; Retrograde labelling (Evans blue) ; Excitability ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Evans blue was injected into either the medial and lateral gastrocnemius or the soleus muscle of adult albino rats to mark retrogradely the corresponding motoneurones in the spinal cord. The labelled motoneurones were identified by the red fluorescence of their perikarya in the ventral horn of segments L4–L6. In addition, a monosynaptic reflex action potential was recorded only in the ventral roots L4–L6 after stimulation of the nerves to the medial and lateral gastrocnemius and the soleus muscle. Excitability and reflex latencies of labelled and unlabelled motoneurones of segments L4–L6 as well as the conduction velocities of their axons were measured. Apart from a small but statistically nonsignificant increase in excitability, no functional differences were found between labelled and control neurones. Thus, retrograde labelling of motoneurones with Evans blue prior to performing electrophysiological experiments has the advantage that the marked motoneurones can be identified under the fluorescence microscope without the need of additional staining or fixation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234034
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  • 76
    Digitale Medien
    Digitale Medien
    Functional difference between “classical” neurosecretory material and vasopressin-like substances of the outer layer of the median eminence (1980)
    Springer
    Cell & tissue research 212 (1980), S. 257-277 
    Details
    ISSN: 1432-0878
    Schlagwort(e): CRF ; Vasopressin ; Adrenalectomy ; Rat ; Histology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In female Wistar rats the influence of adrenalectomy and NaCl administration on the amount of “classical” neurosecretory material (cNSM) in the supraoptico-hypophysial system and on vasopressin-like substance-containing granules (vlG) in the outer layer of the median eminence has been studied. In conjunction with appropriate sodium replacement, adrenalectomy induces an increase in the amount of vlG but does not alter the amount of cNSM. Administration of hypertonic saline diminishes cNSM but has no or only little influence on the amount of vlG. From the findings it is concluded that cNSM and vlG, in spite of their identical histochemical and immunohistochemical properties, have different functions. The functional significance of the vlG is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233960
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  • 77
    Digitale Medien
    Digitale Medien
    Two types of luliberin-immunoreactive perikarya in the preoptic area of the rat (1980)
    Springer
    Cell & tissue research 212 (1980), S. 443-455 
    Details
    ISSN: 1432-0878
    Schlagwort(e): LRF-immunoreactive perikarya ; Preoptic area ; Light and electron microscopic immunocytochemistry ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary At the light microscopic level, following immunostaining with a single antiserum against luliberin (LRF), two types of hormone-producing perikarya in the preoptic area are demonstrated. The two cell types differ in their morphological features: a bipolar, smooth-contoured cell type can be differentiated from an irregularly contoured unipolar type. Intermediate forms between both cell types occurring in the same area are not observed. Electron microscopically, both cell types contain labeled granules of similar size and immunoreactivity. It is dicussed whether the uneven surface of the one cell type is due to areas of synaptic contacts, and whether both cell types are integrated in different neuronal and functional circuits. Moreover, at the ultrastructural level, from the irregularly contoured LRF-producing perikarya a further positively stained cell type, probably a glial cell, can be differentiated. The specific labeling of the latter is caused by its content of immunoreactive lysosomal bodies. Differentiation between the labeled glial cells and the irregularly contoured LRF-producing perikarya is not possible at the light microscopic level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236509
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  • 78
    Digitale Medien
    Digitale Medien
    Differing immunoreactivities of somatostatin in the cortex and the hypothalamus of the rat (1980)
    Springer
    Cell & tissue research 212 (1980), S. 457-464 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Somatostatin immunoreactivity ; Cortex ; Hypothalamus ; Light and electron microscopic immunocytochemistry ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using an antibody against somatostatin (antiserum “F”), two somatostatin-immunoreactive systems, (i) a hypothalamic and (ii) an extrahypothalamic cortical system, are demonstrated in the rat. Another antiserum raised against somatostatin (antiserum “BS 102”) stains only the axons but not the perikarya of the hypothalamic system; the cortical somatostatin system does not react with this antiserum. The electron microscopic findings do not allow decision whether the above-mentioned hypothalamic and cortical neurons possess a common prohormonal form of somatostatin, immunoreactive only with antiserum “F”. They show, however, that the granules in both neuronal systems differ considerably; in the cortical neurons they measure approximately 65 nm in diameter, in the hypothalamic neurons 90–120 nm in diameter. Thus, both somatostatin systems are different and independent from one another.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236510
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  • 79
    Digitale Medien
    Digitale Medien
    An intermittent somatostatin-immunoreactivity in the cortex and basal ganglia of the rat (1980)
    Springer
    Cell & tissue research 205 (1980), S. 327-331 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Somatostatin ; Cortical cells and fibers ; Immunohistochemistry ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using light microscopic immunohistochemistry, somatostatinpositive structures were observed in the cortex of the rat. These structures, including cells and fibers, are widely distributed in all cortical laminae and are also found in the basal ganglia. The positive results were obtained exclusively in two groups of animals sacrificed during two different months of two subsequent years. The reason for this variability in the immunocytochemical stainability of cortical structures remains enigmatic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234691
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  • 80
    Digitale Medien
    Digitale Medien
    Architecture of normal pancreas as revealed by retrograde injection (1980)
    Springer
    Cell & tissue research 205 (1980), S. 445-451 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Exocrine pancreas ; Rat ; Architecture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The architecture of the pancreas was revealed by retrograde injection of the pancreatic ductal system of normal rats with a silicone rubber compound, and subsequent study of the preparation by light microscopy and scanning electron microscopy. The injected material became associated with both ducts and “acinar” areas. Examination of these specimens suggests that the arrangement of the exocrine pancreas is that of a complexly curving and branching system of tubules which anastomose and end blindly. This architecture, which is not that of a true acinar gland, provides a rational basis for the understanding of the simple dedifferentiative changes that accompany pancreatic carcinogenesis, and which have been generally interpreted as representing ductular proliferation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232285
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  • 81
    Digitale Medien
    Digitale Medien
    Electron microscopic immunocytochemical investigation on the postnatal development of the vasopressin system in the rat (1980)
    Springer
    Cell & tissue research 205 (1980), S. 453-471 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Vasopressin system ; Postnatal development ; Ultrastructural immunocytochemistry ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The present ultrastructural results indicate that, in the rat, the vasopressin-synthesizing perikarya of the supraoptic nucleus (NSO) attain a certain degree of maturity earlier than those of the paraventricular nucleus (NPV). In the neonate rat, the stainability of the nuclear areas is very weak; in the perikarya of the NSO a few labeled granules can be found, whereas the perikarya of the NPV often display only a labeled Golgi area, the cytoplasm being devoid of granules. At the end of the first (NSO) and the second (NPV) postnatal weeks, the filling of the neurosecretory granules with vasopressin is inhomogeneous with irregular spots of reaction product distributed on the granules. This feature is less obvious during the following week and has nearly disappeared after the third and fourth postnatal weeks. Already in the neonate two types of vasopressin-positive fibers are observed in the median eminence, characterized by the different diameters of their granules and by their typical location in the internal and the external pericapillary contact zone. Especially in one and two week-old animals, in the internal zone of the median eminence and, to a lesser degree in the neural lobe, the immunocytochemical reaction product is deposited on an axonal tubular network. Judging from the presence of very few vasopressin-negative fibers in the neural lobe of the neonate, the development of the oxytocin system appears to be delayed. A characteristic relationship between pituicytes and the neurosecretory fibers can be observed during the first two postnatal weeks. After the third postnatal week the immunocytochemical features of the vasopressin system correspond approximately to that in adult rats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232286
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  • 82
    Digitale Medien
    Digitale Medien
    Organ culture of the islets of Langerhans from young and senescent rats (1980)
    Springer
    Cell & tissue research 207 (1980), S. 429-448 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Islet of Langerhans ; Aging ; Insulin-secreting cells ; Organ culture ; Electron microscopy ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The B-cells of the endocrine pancreas constitute an adequate model for in vitro study of the aging process in highly differentiated cells. In the present study, collagenase-isolated islets of Langerhans from young and senescent rats were cultured up to 28 days. The response of the B-cells to the stimulatory conditions of the culture medium involved the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, and secretory granules. Correlated data from light microscopy, electron microscopy, and insulin radioimmunoassay show that the differentiation and function of senescent B-cells are maintained in culture, as it has been proven for the B-cells of younger animals. On the other hand, signs of cytological deficiency not directly concerned with the specific function of B-cells were observed: abnormal mitochondria and lysosomes are more numerous in the senescent B-cells. The proliferative capacity of the B-cells of aged rats is reduced.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224618
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  • 83
    Digitale Medien
    Digitale Medien
    Dynamics of the transganglionic movement of horseradish peroxidase in primary sensory neurons (1980)
    Springer
    Cell & tissue research 207 (1980), S. 479-489 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Horseradish peroxidase ; Primary afferent neurons ; Axonal transport ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The dynamics of horseradish peroxidase (HRP) transport in primary sensory neurons were studied in rats by demonstration of the reaction product in spinal nerves, spinal ganglia, dorsal roots and in the spinal cord at different survival times after application of the enzyme to the transected sciatic nerve and to the spinal cord. Using tetramethylbenzidine as the chromogen according to Mesulam (1978), transganglionic transport of HRP was shown in both the disto-proximal direction after peripheral application, and proximo-distal direction after central application. Significant differences in staining intensity between the central and peripheral processes of primary sensory neurons were found after all survival times used in this study. After peripheral application the number of labeled axons and the staining intensity were higher in spinal nerves than in dorsal roots; an inverse situation occurred after central application. These differences as well as the time sequences in staining of different parts of primary sensory neurons suggest that HRP applied to a peripheral nerve and to the spinal cord, respectively, enters the perikarya of spinal ganglion cells in any case before continuing its movement in a cellulifugal direction. Lysosomal degradation of the major portion of the applied HRP is supposed. However, in the post-perikaryal portion of a considerable number of neurons HRP-transport still occurs to a varying extent, thus resulting in labeling of nerve endings. In some neurons a post-perikaryal transport could not be detected light microscopically. The transport rates differ: the calculated transport rate of disto-proximal, cellulipetal movement in the fastest transporting neurons was 7.5 mm/h, that of the disto-proximal cellulifugal movement 2.5 to 3 mm/h.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224621
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  • 84
    Digitale Medien
    Digitale Medien
    Changes of the caecal villi during postnatal development in rats (1980)
    Springer
    Cell & tissue research 208 (1980), S. 253-259 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Villus ; Caecum ; Postnatal development ; Rat ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The villi of the caecal mucosa in postnatal rats were studied using both scanning electron and light microscopy. On the day of birth, numerous villi of various sizes and shapes were present on the caecal mucosa. After the 5th day, the villi decreased very rapidly in length and in number. A strong constriction was observed at the basal region of the caecal villi. During postnatal days 5 ∼ 9 the villi probably separated and disappeared from the caecal mucosa. No villi were observed in rats that were over 10 days of age.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234875
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  • 85
    Digitale Medien
    Digitale Medien
    Morphological investigation of the deep pineal of the rat (1980)
    Springer
    Cell & tissue research 210 (1980), S. 283-294 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Deep pineal ; Pineal complex ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The results presented here reveal that in adult Sprague-Dawley and Wistar rats the pineal gland represents a complex rather than a single organ. Regularly one can distinguish (i) pineal tissue in the intercommissural region as a deep pineal, (ii) a superficial pineal, which represents the major part of the pineal complex, and (iii) nearly always a parenchymal stalk of variable length. The volume of the deep pineal with the adjacent parenchymal stalk exhibits great interindividual variation. It amounts to 127±39×105 μm3 (mean ±standard deviation). The histological appearance of the deep and superficial pineal tissue is fairly similar. The intrinsic cells of the deep and superficial pineal differ in nuances only. Karyometry reveals that the nuclear volumes of the intrinsic cells of the deep pineal are very variable ranging from 90–450 μm3, with a mean value of 207 μm3. The changes over a period of 24 h reach statistical significance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237616
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  • 86
    Digitale Medien
    Digitale Medien
    Effect of polymeric additives on the rheological properties of talc-filled polypropylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 198-201 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effect of small amounts of low molecular weight polypropylene oxide on the rheological properties of talc-filled polypropylene composites was studied experimentally using a capillary viscometer. The elastic behavior of the system was investigated by exit pressure and die swell methods. Initial studies showed that the talc filler does not influence the viscosity of the polypropylene but decreases the elasticity of the polymer system. Addition of oligomer concentration in a 40 wt percent talc-filled polypropylene not only decreases the viscosity but also further decreases considerably the elasticity of the filled polymer composite. In both cases about 3 wt percent oligomer cone entration appears to be optimal, and further addition of oligomer does not significantly influence the rheological characteristics of the talc-filled polypropylene composite.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200305
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  • 87
    Digitale Medien
    Digitale Medien
    Synthesis of permselective membranes by radiation induced grafting of hydrophilic monomers into poly(tetrafluoroethylene) filmsPresented in part at the following conference: IVPAC Internation Symposium Macromol. Chem.; 1961, Montreal, 1961, Montreal, 1967, Bruxelles, 1976, Jerusalem; A.C.S. National Meeting, April 1968, San-Francisco (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 202-205 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A large variety of permselective membranes were prepared by radiation grafting techniques. Grafting of styrene into poly-(tetrafluoroethylene) films followed by sulfonation led to strong anionic membranes showing good performance in reverse osmosis. Carboxylic membranes were prepared by grafting acrylic and methacrylic acids. Cationic membranes were obtained via grafting 4-vinylpyridine. These membranes were tested in various fractionation processes including reverse osmosis. N-vinylpyrrolidone grafts exhibited high selectivity for separating water from organic solvents by pervaporation. Bifunctional membranes containing both carboxylic and pyridine groups were obtained by two successive grafting steps either in bulk giving rise to “homogeneous” membranes with unusual swelling properties, or into localized areas generating mosaic membranes which exhibit negative osmosis and increased rates of ion-pair diffusion.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200306
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  • 88
    Digitale Medien
    Digitale Medien
    Topomorphic states and phase transitions connected with the crystallization of polymersPresented at the 5th Discussion Conference on Phases and Interphases in Polymers, Prague (1976) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 206-211 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The crystallization of flexible-chain molecules of different degrees of coiling is considered. The nature of the phase transition during crystallization is discussed. The revision of established notions on phase transitions in polymers leads to the concept of crystalline topomorphism, i.e., the existence of two crystalline types with different modes of packing of macromolecules in the macroscopic crystal though they belong to the same lattice class: folded-chain crystal (FCC) and extended-chain crystal (ECC). Phase diagrams in coordinates of degree of coiling vs temperature are plotted. The values of molecular orientation and temperatures at which each of both mechanisms of crystallization takes place are evaluated. The mechanisms of ECC growth under equilibrium conditions and under conditions of molecular orientation are discussed. It is shown that the melting of ECC obtained by the process of orientational crystallization is a second order phase transition, being analogous to a crystal-nematic phase transition. At the same time the melting of FCC provides all the features of a first order transition.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200307
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  • 89
    Digitale Medien
    Digitale Medien
    Plane stress and plane strain fractures in polypropylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 215-220 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The concepts of Linear Elastic Fracture Mechanics (LEFM) are applied to polypropylene, a homopolymer and two copolymers, with a view to characterizing their brittle behavior at slow rates (0.5 cm/min) in terms of a fracture toughness, KIc. The effect of thickness, notch sharpness, and the mode of loading on KIc have been investigated in order to determine the plane strain toughness values, KcI for the materials. The two types of material are compared in terms of their toughness values over a range of temperatures between +30 and -160°C. Evidently, the small amounts of ethylene added to the copolymers show plasticizing effects, suppressing the yield stress and the ductile-brittle transition temperature. In addition, the copolymers exhibit a ductile-brittle region between -100 and -45°C where notch strengthening is apparent in the tension mode and a slow crack growth region between -45 and -30°C where slow growth precedes unstable fracture. The homopolymer, however, shows no clear evidence of such intermediate regions, except for slight amounts of slow growth above 0°C, and becomes ductile around 30°C.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200309
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  • 90
    Digitale Medien
    Digitale Medien
    Introductory remarks (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 237-237 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200402
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  • 91
    Digitale Medien
    Digitale Medien
    Residual stresses and aging in injection molded polypropylene (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 230-236 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The residual stresses in injection molded bars of polypropylene have been examined using a stress relaxation method and by the layer removal technique. A positive value for the internal stress parameter was obtained with newly molded specimens and was found to be retained by specimens stored at liquid nitrogen temperature. The stress relaxation parameter reduced to zero both for specimens aged at room temperature and also for those aged at -40°C. Nevertheless the relaxation behavior of specimens aged at all three temperatures was quite distinct. The layer removal technique showed that the stresses near to the surface were compressive and those in the interior tensile, in apparent contradiction to the interpretation of Kubat and Rigdahl for the meaning of a positive internal stress parameter. A marked reduction in stress levels on aging at room temperature was confirmed, however. The relevance of the relaxation spectrum of polypropylene to these observations is discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200311
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  • 92
    Digitale Medien
    Digitale Medien
    Diffusion with discontinuous swelling. IV. Type II diffusion into spherical particles (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 238-243 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In the last few years some new features of the so-called type II diffusion have been established which confirm the first theoretical description of such a material transport into a semi-infinite glassy medium which at a certain concentration of the sorbate is transformed into a gel. The boundary between the glass and the gel progresses at a constant velocity into the interior of the sample thus yielding a linear term in the weight gain. The gradual establishment of the concentration profile in front of this boundary yields at the beginning a square root term in the weight gain. A detailed analysis of the extensive measurements of Hopfenberg, et al. of the diffusion of n-hexane into extremely small polystyrene spheres demonstrates that the weight gain always starts with a square root of time term. In sufficiently large spheres this contribution is soon completely overridden by the term linear in time. The spherical geometry substantially modifies the concentration profile and the weight gain. In particular the weight gain divided by the square root of time vs the square root of time shows a maximum as soon as the geometrical factors prevail over the effect of the constant velocity progression of the boundary between the glass and the gel.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200403
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  • 93
    Digitale Medien
    Digitale Medien
    A study of crosslinking in polyimides by viscoelastic and diffusion techniques (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 244-251 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: This paper is concerned with detecting crosslinking and changes in crosslink densities in cured polyimides. The methods used include diffusional weight gain and dynamic mechanical measurements on thin films of the cured polymers. In this study changes in diffusivities (D) for dimethylformamide (DMF) sorption into polyimide films as well as dynamic mechanical moduli and loss tangents are shown to be related to differences in polyimide cure schedule and composition. In all cases studied there is a β loss dispersion in the range 120 to 150°C and a γ loss dispersion in the range -50 to -80°C. The position and intensity of the β and γ relaxation processes vary primarily with cure cycle. There is a significant correlation between the magnitude of the diffusion coefficient and β and γ transition temperatures (Tβ and Tγ). Tβ increases and Tγ decreases with higher values of D so that T*, the difference Tβ - Tγ, is directly proportional to the diffusivity. By relating these results to data in the literature and the known curing behavior of polyimides, this trend is shown to be consistent with the presence of crosslinking and to be related to the crosslink density of the polymers. The data of this study indicate that measurements of diffusion coefficients for solvent sorption can be used to study changes in crosslink densities in glassy thermosetting polymers. Since the method is best suited for studying one dimensional diffusion, it also is suggested as a possibility for determining relative crosslink densities in adhesives bonded between substrates.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200404
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  • 94
    Digitale Medien
    Digitale Medien
    Sorption and diffusion of ionic dyes in anionic cellophane membranesPresented in part at the “Textilwissenschaftliches Forum” Elmau (West Germany) (1975) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 264-270 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Experimental steady-state permeability studies have been made with non-ionic, anionic and cationic dyes using carboxy cellulose membranes as anionic substrates. The experimental results show that with increasing bulk ionic strength the diffusion velocities of anionic and cationic compounds increase and decrease, respectively. The diffusion behavior of non-ionic compounds is independent of the ionic strength. Empirical relationships have been deduced which fit the permeation data of the anionic compounds. A new concept is introduced which postulates that the diffusion behavior of colons within an anionic membrane is dependent on the basicity of the fixed ionic groups. In substrates with matrix-bound anionic groups of high basicity, such as carboxy cellulose, the permeability behavior is described in terms of a new diffusion mechanism referred to as the “fluctuating” charge mechanism. This concept can provide a semi-quantitative understanding of the different electrostatic obstruction effects which matrix-bound carboxylate and sulfonate groups have on the permeability of colons. The measured permeability of the counter ions is in qualitative agreement with the proposed diffusion model.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200407
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  • 95
    Digitale Medien
    Digitale Medien
    The glass point of elastin as a function of diluent concentration (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 290-293 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Elastin shares the properties of rubberlike elasticity and its capability to form a glass with crosslinked polymers in general. The glass transition temperature of dry elastin at 200°C is strongly depressed by water, as well as by ethylene glycol. On a volume fraction basis, both diluents depress the glass point equally. This result is strong evidence against any specific binding of diluent molecules and indicates relatively high mobility of diluent molecules in glassy elastin. This deduction is in agreement with the conclusions reached on the basis of heat capacity and dielectric measurements. Proposed small sections of β turns in the elastin chain are compatible with the concept of naturally occurring elastin chains in the amorphous state. Our results, however, do not confirm the existence of proposed β spirals with periodicities of 100 Å which were suggested to be the basis for the banded filaments observed in electron micrographs.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200412
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  • 96
    Digitale Medien
    Digitale Medien
    Sorption and transport of water vapor in glassy poly(acrylonitrile) (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 300-304 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Sorption data for H2O in glassy poly(acrylonitrile)(PAN) are presented for a range of relative vapor pressures at temperatures from 20 to 50°C. Simple dual mode sorption, involving “hole-filling” and molecular solution appears to dominate the low activity region of sorption. Based on the clustering analysis suggested by Zimm and Lundberg, pronounced clustering of penetrant appears to occur above a relative pressure of 0.6. The form of the effective concentration-dependent diffusion coefficient for H2O in PAN, determined by analysis of steady state permeation data, suggests that water in the microvoids and clusters has a lower mobility than the molecularly dissolved water in the polymer matrix. Time lag measurements at high upstream relative water vapor pressures suggest that the transient state permeation has a non-Fickian character due to relaxations which occur slowly to accommodate the clustering process.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200414
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  • 97
    Digitale Medien
    Digitale Medien
    Masthead (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980) 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200501
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  • 98
    Digitale Medien
    Digitale Medien
    Water vapor transport in an epoxy resin based on TGMDA and DICY (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 310-314 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Water uptake has been measured in an epoxy resin based on tetraglycidylmethylenedianiline curved with dicyanidamide. The curing behavior of this system as elucidated by differential scanning calorimetry and Fourier transform infrared is complex. Based upon this information we selected curing temperatures and times in addition to the “standard” cure. The kinetics of the sorption of water by the materials which have undergone the standard cure indicate that the two modes of sorption are involved at high humidity and only a single mode at lower humidity (as seen by changes in the slope of the log Mt vs log t plots). The kinetics of the sorption in the resins which have undergone post cure at higher temperatures also indicate two or more modes of sorption at high humidities. However the slopes of the log Mt vs log t plots differ from those for the resin with standard cure. Subsequent sorption/desorption cycles on the standard cure resin showed marked increases in the initial sorption rate as well as changes in mode, suggesting that irreversible changes in the resin had occurred.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200416
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  • 99
    Digitale Medien
    Digitale Medien
    Finite element solutions for flow in a single-screw extruder, including curvature effects (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 339-348 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Slow developed flow in an extruder channel has been set up as a two-dimensional, variational problem using a helical coordinate system, thus avoiding the usual geometrical simplification. Continuity is enforced by an integral form of constraint, and solutions for isothermal, Newtonian flow are obtained by a finite element method for both shallow and deep, highly curved channels. The performance of the solution procedure as a function of Lagrangian multiplier is discussed. Convergence to correct solutions is demonstrated for the shallow channel case. Deep channel results are compared with analytic predictions, curvature corrected according to Booy. Further testing of deep channel results will be made against experimental data.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200505
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  • 100
    Digitale Medien
    Digitale Medien
    Corona-discharge treatment of polymeric films, II: Chemical studies (1980)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 20 (1980), S. 330-338 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polymeric films, chiefly polyethylenes, were subjected to corona-discharge treatment in a continuous treater at commercial rates in a program covering wide ranges of the main processing factors (2). Electron-spin-resonance measurements on freshly treated films found no free radicals. Reactions of the treated surfaces with a free-radical compound, diphenyl picryl hydrazyl (DPPH) were studied, focusing mainly on the rate effects. The evidence indicates that corona treatment produces fairly stable peroxide structures of the forms RO2R and RO3R on polyethylene surfaces. RO3R reacts rapidly with DPPH alone, while RO2R undergoes a slower reaction after addition of the catalyst, triethylene diamine. DPPH is capable of detecting as few as 1013 peroxide groups per square centimeter. Activation energies were 12 kcal/mole for the uncatalyzed reaction and 16 kcal/mole for the amine-catalyzed reaction. As with the physical effects reported earlier (2), the production of peroxides is most strongly dependent on the energy delivered to the film during treatment. This energy is proportional to the quotient of corona current and web speed, I/S, Regression analysis showed that air-gap thickness, relative humidity, and number of electrodes used also were significant factors, while dielectric thickness and corona frequency were not. We found that-γSP, the polar component of surface energy of the treated film, which is nearly zero for untreated polyethylenes, is exponentially related to the concentrations of both RO2R and RO3R with a correlation coefficient for 92 specimens tested of 0.88. We believe this is the first strong evidence linking treatment factors, at commercial levels of treatment, to chemistry of the treated surface and linking both of those to changes in physical behavior of the surface.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760200504
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