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  • 1990-1994  (3,281)
  • 1980-1984  (2,284)
  • Computational Chemistry and Molecular Modeling  (4,032)
  • Rat  (1,531)
  • Nuclear reactions
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  • 101
    Electronic Resource
    Electronic Resource
    Crossmodal divided attention in rats: effects of chlordiazepoxide and scopolamine (1994)
    Springer
    Psychopharmacology 115 (1994), S. 213-220 
    Details
    ISSN: 1432-2072
    Keywords: Divided attention ; Scopolamine ; Chlordiazepoxide ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract “Divided attention” is a psychological construct that hinges on assumptions about a fixed finite capacity of subjects to simultaneously process multiple sets of information. A model of a crossmodal divided attention task was developed in rats. Initially, rats were trained consecutively in operant auditory and visual conditional discrimination tasks. The final task consisted of two successive blocks of 20 trials per modality (modality certainty), followed by 60 trials comprising a semi-randomized sequence of stimuli of both modalities (auditory or visual) and qualities (flashing/pulsing or constantly turned on; modality uncertainty). In comparison to unimodal blocks of trials, performance in the mixed condition was assumed to reflect the demands on the parallel processing of two sets of stimulus-response rules. While response accuracy remained unchanged, response latencies were generally longer in the bimodal condition. Administration of scopolamine (0.03, 0.06, 0.1 mg/kg) or chlordiazepoxide (1, 3, 5, 8 mg/kg) dose-dependently increased response latencies. The scopolamine-induced increase in response latencies was greater in the mixed condition. Cost-benefit analyses demonstrated that the absolute divided attention costs (in ms) were generally higher for visual than for auditory stimuli. Both drugs produced qualitatively similar effects; however, scopolamine was more potent in increasing the absolute divided attention costs than chlordiazepoxide. These data are discussed in terms of the validity of this animal paradigm, and of hypotheses about the effects of benzodiazepine receptor agonists and muscarinic antagonists on brain information processing capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244774
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  • 102
    Electronic Resource
    Electronic Resource
    CCK-A and CCK-B selective receptor agonists and antagonists modulate olfactory recognition in male rats (1994)
    Springer
    Psychopharmacology 115 (1994), S. 435-440 
    Details
    ISSN: 1432-2072
    Keywords: Behaviour ; Olfactory recognition ; Social investigation ; Neuropeptides ; Cholecystokinin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Modulation of learning and memory is one of the physiological roles that the neuropeptide cholecystokinin (CCK-8) may play. We have used a behavioural model of olfactory recognition among rats to test this hypothesis and to explore the relationship between CCK-A and CCK-B receptors and memory retention. Adult male rats form a transient memory of a juvenile congenere as indicated by a reduction in the duration of investigatory behaviour upon re-exposure 30 min after an initial exposure, but not when re-exposure is delayed until 120 min afterwards. In the present study, rats were treated after the first contact with various compounds; inhibition and facilitation of olfactory recognition were evaluated as the persistence in investigation 30 min and the decrease in investigation 120 min after pharmacological manipulations, respectively. Systemic injection of CCK-8, of a selective CCK-A agonist, or of non-peptide CCK-B antagonists (CI-988 and LY-262691) enhanced olfactory recognition. In contrast, the CCK-B selective agonist BC 264 and the tetrapeptide CCK-4 both disrupted it. Taken together with previous evidence of the detrimental effect of the non-peptide CCK-A antagonist devazepide on olfactory recognition, these results confirm and extend the hypothesis that there is a balance between CCK-A-mediated facilitative effects and CCK-B-mediated inhibitory effects on memory retention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245565
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  • 103
    Electronic Resource
    Electronic Resource
    Parallel changes in dopamine D2 receptor binding in limbic forebrain associated with chronic mild stress-induced anhedonia and its reversal by imipramine (1994)
    Springer
    Psychopharmacology 115 (1994), S. 441-446 
    Details
    ISSN: 1432-2072
    Keywords: Chronic mild stress ; Imipramine ; Animal model of depression ; Dopamine ; D1-receptors ; D2-receptors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic sequential exposure to a variety of mild stressors has previously been found to cause an antidepressant-reversible decrease in the consumption of palatable sweet solutions, associated with abnormalities of dopaminergic neurotransmission in the nucleus accumbens. In the present study, 5 weeks of treatment with imipramine (10 mg/kg b.i.d.) reversed the decreased sucrose intake of rats exposed to chronic mild stress. Stress also caused a decrease in D2-receptor binding in the limbic forebrain (but not the striatum), which was completely reversed by imipramine. In nonstressed animals, imipramine decreased D1-receptor binding in both regions. However, in stressed animals, imipramine did not significantly alter D1-receptor binding in either area. Stress alone slightly increased D1-receptor binding, in striatum only. Scatchard analysis showed that all changes in receptor binding resulted from changes in receptor number (Bmax) rather than receptor affinity (KD). The results support the hypothesis that changes in D2-receptor function in the nucleus accumbens are responsible for chronic mild stress-induced anhedonia and its reversal by antidepressant drugs. They do not support the hypothesis that the sensitization of D2-receptors seen following chronic antidepressant treatment is caused by a down-regulation of D1-receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245566
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  • 104
    Electronic Resource
    Electronic Resource
    Up-regulation of β1-adrenergic receptors in rat brain after chronic citalopram and fluoxetine treatments (1994)
    Springer
    Psychopharmacology 115 (1994), S. 543-546 
    Details
    ISSN: 1432-2072
    Keywords: β1-adrenergic receptors ; Rat ; Brain ; Citalopram ; Fluoxetine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Quantitative receptor autoradiography was used to study the effects of the selective serotonin reuptake inhibitors citalopram and fluoxetine and the tricyclic antidepressant imipramine on the regulation of β1-adrenergic receptors in the rat brain. Rats were treated with saline, citalopram (10 mg kg−1), fluoxetine (10 mg kg−1), or imipramine (15 mg kg−1) SC once daily for 14 days. [125I]Iodocyanopindolol binding to β1-adrenergic receptors was found to increase significantly in the caudate-putamen and the somatosensory areas of the frontal cortex after both citalopram and fluoxetine treatments. Imipramine treatment elicited a marked decrease in β1 binding in the outer laminae of the cingulate cortex, as well as in the motor and somatosensory areas of the frontal cortex. In a separate experiment, rats were treated with saline, citalopram (2.5, 10 and 20 mg kg−1) or fluoxetine (2.5, 10 and 20 mg kg−1) SC once daily for 14 days. The effects of citalopram and fluoxetine on β1 receptors in the somatosensory cortex and caudate-putamen were replicated. These results demonstrate that chronic administration of selective serotonin reuptake inhibitors, in contrast to imipramine, can cause a regional up-regulation of β1-adrenergic receptors in the rat brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245579
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  • 105
    Electronic Resource
    Electronic Resource
    Facilitated acquisition of a temporal discrimination following destruction of the ascending 5-hydroxytryptaminergic pathways (1994)
    Springer
    Psychopharmacology 116 (1994), S. 373-378 
    Details
    ISSN: 1432-2072
    Keywords: 5-Hydroxytryptamine ; 5,7-Dihydroxytryptamine ; Operant behaviour ; Timing ; Interval bisection procedure ; Acquisition ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This experiment examined the effect of destroying the 5-hydroxytryptaminergic (5HTergic) pathways on the acquisition and performance of discrimination between two brief time intervals. Rats that had received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei, and sham-lesioned control rats were trained in a series of discrete trials to press lever A following a 200-ms presentation of a light stimulus and lever B following an 800-ms presentation of the same stimulus. Both groups gradually acquired accurate performance, attaining 80%–85% accuracy by the end of 40 sessions. The lesioned group learnt the task significantly faster than the control group. When stable performance had been attained, “probe” trials were introduced in which the light was presented for intermediate durations. Both groups showed sigmoid functions relating percent choice of lever B to log stimulus duration. The bisection point (duration corresponding to 50% choice of lever B) did not differ significantly between the two groups; however, the Weber fraction was significantly smaller in the lesioned group than in the control group. The levels of 5HT and 5-hydroxy-indole-acetic acid were markedly reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered. The results indicate that destruction of the 5HTergic pathways facilitates acquisition of a temporal discrimination. The lack of an effect of the lesion on the bisection point contrasts with our previous finding using longer stimulus durations; it is suggested that different behavioural processes may underlie millisecond-range and second-range temporal discrimination, and that these may be differently affected by 5HT depletion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245343
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  • 106
    Electronic Resource
    Electronic Resource
    The atypical antipsychotic, remoxipride, blocks phencyclidine-induced disruption of prepulse inhibition in the rat (1994)
    Springer
    Psychopharmacology 116 (1994), S. 437-442 
    Details
    ISSN: 1432-2072
    Keywords: Antipsychotic agents ; Acoustic startle ; Prepulse inhibition ; Schizophrenia ; Phencyclidine ; Remoxipride ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of various typical (haloperidol) and atypical (clozapine, raclopride, remoxipride) antipsychotics on phencyclidine (PCP)-induced disruption of sensorimotor gating was tested in rats using an acoustic startle paradigm. Clozapine (4–40 µmol/kg), haloperidol (1–5 µmol/kg) and raclopride (1–12 µmol/kg) failed to reverse PCP-induced disruption of prepulse inhibition (PPI) of the acoustic startle response. In contrast, remoxipride (12–60 µmol/kg) caused a dose-dependent block of this effect. PCP-induced disruption of PPI is a widely accepted animal model of a corresponding behavioural deficit observed in schizophrenia although little evidence has been presented that it is in fact sensitive to antipsychotic agents. The present results indicate that remoxipride behaves in a unique way in this model compared to clozapine, haloperidol and raclopride.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247475
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  • 107
    Electronic Resource
    Electronic Resource
    5-HT1A receptor agonists improve the performance of normal and scopolamine-impaired rats in an operant delayed matching to position task (1994)
    Springer
    Psychopharmacology 116 (1994), S. 135-142 
    Details
    ISSN: 1432-2072
    Keywords: Short term memory ; Delayed matching to position ; 5-HT ; 5-HT1A receptor ; 8-OH DPAT ; Ipsapirone ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A series of experiments examined the effects of 5-HT1A ligands alone and in combination with the muscarinic antagonist scopolamine on short term working memory in the rat. The behavioural paradigm was a discrete trial, operant delayed matching to position task, with delays of 0, 5, 15 and 30 s. The 5-HT1A ligands tested were the full agonist, 8-OH DPAT (0, 0.1, 0.3 and 1 mg/kg), the partial agonist, ipsapirone (0, 1, 3 and 10 mg/kg), and the purported antagonist, NAN 190 (0, 1, 2, and 4 mg/kg). 1-PP (0, 0.1, 0.3, 1 mg/kg), the major metabolite of ipsapirone, was also tested. The lowest dose of 8-OH DPAT significantly improved matching accuracy at the longest delay, whereas the highest dose impaired matching accuracy and increased the latency to respond. Ipsapirone also significantly improved the accuracy of performance at a dose of 3 mg/kg, but the doses of 1 and 10 mg/kg did not significantly affect performance. NAN-190, at the highest dose tested (4 mg/kg), impaired matching accuracy, whereas the two lower doses did not significantly affect performance. The highest dose also increased the latency to respond. 1-PP had no effect on performance. Scopolamine HBr (0.14 mg/kg) caused a delay dependent impairment in matching accuracy, and had no effect on missed trials or the latency to respond. Low doses of 8-OH DPAT (0.1 and 0.3 mg/kg) significantly attenuated the scopolamine induced accuracy impairment, whereas 1 mg/kg 8-OH DPAT potentiated the impairment. Ipsapirone (3 mg/kg) also significantly improved the performance of scopolamine impaired rats. NAN-190 increased the latency to respond and reduced the number of nose pokes made during the delays in scopolamine-treated rats, and tended to potentiate the scopolamine-induced accuracy impairment. 1-PP did not affect the performance of scopolamine treated rats. Taken together, these results suggest that modulation of 5-HT1A receptors influences short term spatial working memory in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245055
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  • 108
    Electronic Resource
    Electronic Resource
    The neurosteroid pregnenolone sulfate blocks NMDA antagonist-induced deficits in a passive avoidance memory task (1994)
    Springer
    Psychopharmacology 116 (1994), S. 201-206 
    Details
    ISSN: 1432-2072
    Keywords: Neurosteroid ; Memory ; Amnesia ; NMDA receptor ; Ataxia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The neurosteroid pregnenolone sulfate (PS) has been recently shown to positively modulate NMDA receptors and to have memory enhancing properties in mice. In the present study, we examined the ability of PS to increase retention performance and to reduce deficits induced by a competitive NMDA receptor antagonist, the 3-((±)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), in a step-through passive avoidance task in rats. Pretraining administration of PS (0.84–1680 pmol, ICV) had minimal effects on retention performance assessed 24 h after training, while CPP significantly decreased retention performance at the doses of 1.2 and 1.6 nmol (ICV). However, when administered in combination with CPP (1.2 nmol), PS (0.84–840 pmol, ICV) dose-dependently blocked the deficit in passive avoidance response induced by the NMDA antagonist. At the dose of 840 nmol, PS also significantly reduced the motor impairment induced by CPP (1.2 nmol). The blockade of CPP-induced behavioral deficits by PS may result from its positive modulatory action at NMDA receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245063
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  • 109
    Electronic Resource
    Electronic Resource
    Investigations of fetal development models for prenatal drug exposure and schizophrenia. Prenatald-amphetamine effects upon early and late juvenile behavior in the rat (1994)
    Springer
    Psychopharmacology 116 (1994), S. 226-236 
    Details
    ISSN: 1432-2072
    Keywords: Fetus ; Prenatal drug exposure ; Schizophreniad-Amphetamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent evidence suggests that mid-pregnancy is a critical period for production of fetal abnormalities that cause behavioral and neuropathological changes in adult offspring. The present experiments provide an animal model of these effects by treating pregnant Sprague-Dawley rats during gestational days 11–14 withd-amphetamine (AM). Offspring were tested for neurological signs, foraging activity, reversal learning, and sensitivity to amphetamine challenge. In the Early Juvenile period, postnatal days (PND) 20–30, female AM offspring initially showed reductions in rearing, holepoking, and midfield activity. On later trials, and as young adults, AM females showed signs of locomotor hyperactivity despite continued poor foraging efficiency, and were also more sensitive to a 1.0 mg/kgd-amphetamine challenge. AM males showed initially slower and more perseverative responding than controls, but then developed excessive response switching. These changes continued during tests for Retention, Reversal, and Extinction in the Late Juvenile/Early Adult stage (PND 50–90), when both AM-exposed sexes showed increased eating time, significantly more perseverative lateral turning preference (right or left), and slower reversal learning than controls. Behavioral data were consistent with aberrations in thalamo-frontal and mesolimbic/nigrostriatal projection systems that have been reported in AM animals and which are also affected by maternal drug abuse and schizophrenia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245066
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  • 110
    Electronic Resource
    Electronic Resource
    Chronic haloperidol treatment leads to an increase in the intramembrane interaction between adenosine A2 and dopamine D2 receptors in the neostriatum (1994)
    Springer
    Psychopharmacology 116 (1994), S. 279-284 
    Details
    ISSN: 1432-2072
    Keywords: Adenosine A2 receptor ; Dopamine D2 receptor ; Methylxanthine ; Tardive dyskinesias ; Receptor-receptor interaction ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stimulation of adenosine A2 receptors (with the selective adenosine A2 agonist CGS 21680) in rat striatal membrane preparations, produces a decrease in both the affinity of D2 receptors and the transduction of the signal from the D2 receptor to the G protein. This intramembrane A2-D2 interaction might be responsible for the behavioural depressant effects of adenosine agonists and for the behavioural stimulant effects of adenosine antagonists such as caffeine and theophylline. Dopamine denervation induces an increase in the intramembrane A2-D2 interaction, which may underlie the observed higher sensitivity to the behavioural effects induced by adenosine antagonists found in these animals. The present study was designed to examine if chronic treatment with haloperidol, which also produces dopamine receptor supersensitivity, is also associated with an increase in the intramembrane A2-D2 interaction in the neostriatum and with a higher sensitivity to the behavioural effects induced by adenosine antagonists. The data showed that: (i) haloperidol pretreatment causes a higher binding of the D2 antagonist [3H] raclopride in striatal membrane preparations due to an increase in the number of D2 receptors without changes in their affinity for the antagonist (increase in Bmax without changes in kd); (ii) GCS 21680 decreases the affinity of dopamine for the D2 receptor, by increasing the equilibrium dissociation constants of high (Kh) and low affinity (K1) dopamine D2 binding sites and increases the proportion of high affinity binding sites (Rh); (iii) a low dose of CGS 21680 (3 nM), which is ineffective in membrane preparations from neostriatum of nontreated animals, is effective in membranes from the striatum of haloperidol-pretreated animals; (iv) the nonselective adenosine antagonist theophylline (20 mg/kg SC) causes a higher motor activation in rats pretreated with haloperidol. The possible relevance of these results for the pathophysiology and treatment of tardive dyskinesias is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245329
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  • 111
    Electronic Resource
    Electronic Resource
    Sex-dimorphic psychomotor activation after perinatal exposure to (−)-Δ9-tetrahydrocannabinol. An ontogenic study in wistar rats (1994)
    Springer
    Psychopharmacology 116 (1994), S. 414-422 
    Details
    ISSN: 1432-2072
    Keywords: Rat ; Development ; Δ-9-Tetrahydrocannabinol ; Motor behavior ; Locomotor activity ; Grooming ; Corticosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ontogeny and the adult expression of motor behaviors were studied in male and female rats born from mothers exposed to Δ9-tetrahydrocannabinol (THC, 5 mg/kg) during gestation and lactation. Perinatal exposure to THC increased both rearing and locomotor activities in males and females at immature preweanling ages (P-15 and P-20). These effects disappeared after ceasing THC exposure (postweaning ages), but they were observed again in adult (P-70) females. The effects appeared as persistently high motor activity in familiar environments, disappearing the characteristic habituation profile in locomotor and exploratory behaviors. In novel environment condition tests, adult (P-70) THC-exposed females, but not males, exhibited lower locomotor activity in the socio-sexual approach test, and an increase in the emergence latency in the dark-light emergence test. Additionally, animals of both sexes exposed to THC showed a increase in the time spent grooming measured in novelty conditions. These findings suggest that perinatal exposure to THC affects both the development and the adult expression of motor behaviors and it resulted in a sex-dimorphic psychomotor activation very similar to that observed after perinatal exposure to other drugs of abuse. A possible role of THC-induced pituitary-adrenal (PA) axis activation was also evaluated by measuring plasma corticosterone levels in adult animals perinatally exposed: THC-exposed females exhibit a clear increase of this adrenal hormone, whereas THC-exposed males displayed lower levels of this hormone. These results confirm our previous finding of a sex-dimorphic behavioral response to perinatal exposure to hashish extracts, and they suggest a role of THC-induced PA activation in the mediation of these actions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247471
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  • 112
    Electronic Resource
    Electronic Resource
    A comparison of the effects of the D1 receptor antagonists SCH 23390 and SCH 39166 on suppression of feeding behavior by the D1 agonist SKF38393 (1994)
    Springer
    Psychopharmacology 113 (1994), S. 328-333 
    Details
    ISSN: 1432-2072
    Keywords: Dopamine ; 5-HT2 ; 5-HT1C ; D1 ; SKF 38393 ; SKF 82958 ; SCH 39166 ; SCH 23390 ; Feeding ; Behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The hypophagic effect of the D1 receptor agonist SKF 38393 is not dose-dependently antagonized by the D1 antagonist SCH 23390. Moreover, the receptor specificity of this interaction remains in question, since SCH 23390 has significant activity at both 5-HT2 and 5-HT1C receptors, and SKF 38393 also interacts with 5-HT1C receptors. To determine the relative significance of these actions, a comparison was made between the anorectic effects in rats of SCH 23390 (0.1–1.0 mg/kg) and the benzonaphthazepine SCH 39166 (0.1–3.0 mg/kg), a D1 antagonist with negligible affinity for 5-HT sites. Both compounds inhibited food-intake dose-dependently, with SCH 23390 being approximately twice as potent as SCH 39166. Behaviorally inactive and active doses of both antagonists were tested in combination with the D1 agonist SKF 38393 (10–56 mg/kg). Neither antagonist was able to produce more than a marginal attenuation of the agonist-induced hypophagia. This demonstrates that previous failures to reverse the behavioral actions of SKF 38393 by SCH 23390 were not due to specific actions of this particular antagonist. Finally, like SCH 23390, SCH 39166 (0.3 mg/kg) was able to attenuate fully the anorectic effects of the D1 agonist SKF 82958 (1.0 and 3.0 mg/kg), demonstrating that neither compound is intrinsically unable to block D1 receptor-mediated hypophagia. The results demonstrate the generality of the D1 antagonist-mediated effect on feeding and call into question the use of SKF 38393 as a D1 agonist in studies of feeding, and perhaps in other contexts as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245205
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  • 113
    Electronic Resource
    Electronic Resource
    Prepulse inhibition of the acoustic startle response of rats is reduced by 6-hydroxydopamine lesions of the medial prefrontal cortex (1994)
    Springer
    Psychopharmacology 113 (1994), S. 487-492 
    Details
    ISSN: 1432-2072
    Keywords: Prefrontal cortex ; Dopamine ; Acoustic startle response ; Prepulse inhibition ; 6-Hydroxydopamine ; Rat ; Schizophrenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prepulse inhibition (PPI) of the acoustic startle response (ASR) is impaired by dopamine (DA) overactivity in the nucleus accumbens and anteromedial striatum. Since there is evidence that DA in the medial prefrontal cortex exerts an inhibitory control on striatal DA systems, it was investigated whether depletion of prefrontal DA reduces PPI. Rats were tested for PPI both before and after injections (2 × 1 µl per side) of vehicle, a low (3.0 µg/µl) or a high (6.0 µg/µl) dose of 6-hydroxydopamine hydrobromide (6-OHDA) into the prefrontal cortex. Only the high dose of 6-OHDA, leading to an 87% depletion of prefrontal DA, impaired PPI. The ability of an acoustic prepulse (75 dB, 10 kHz) to reduce the response to a startle pulse (100 dB noise burst) was maintained in sham lesioned rats, but was significantly disturbed in rats lesioned with the high dose of 6-OHDA. The 6-OHDA treatment did not affect the ASR amplitude in the absence of a prepulse. The reduction of PPI in lesioned rats correlated with the extent of DA depletion. These results suggest that the DA innervation of the prefrontal cortex is involved in the modulation of the ASR and they provide further evidence for opposite actions of prefrontal and subcortical DA systems in the control of behaviour. The present findings are discussed with regard to the potential role of prefrontal DA in schizophrenia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245228
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  • 114
    Electronic Resource
    Electronic Resource
    Regional brain distribution of risperidone and its active metabolite 9-hydroxy-risperidone in the rat (1994)
    Springer
    Psychopharmacology 114 (1994), S. 53-62 
    Details
    ISSN: 1432-2072
    Keywords: Risperidone ; 9-Hydroxy-risperidone ; Active metabolite ; Antipsychotic ; 5-HT2 Antagonist ; Dopamine-D2 antagonist ; Pharmacokinetics ; Regional brain distribution ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Risperidone is a new benzisoxazole antipsychotic. 9-Hydroxy-risperidone is the major plasma metabolite of risperidone. The pharmacological properties of 9-hydroxy-risperidone were studied and appeared to be comparable to those of risperidone itself, both in respect of the profile of interactions with various neurotransmitters and its potency, activity, and onset and duration of action. The absorption, plasma levels and regional brain distribution of risperidone, metabolically formed 9-hydroxy-risperidone and total radioactivity were studied in the male Wistar rat after single subcutaneous administration of radiolabelled risperidone at 0.02 mg/kg. Concentrations were determined by HPLC separation, and off-line determination of the radioactivity with liquid scintillation counting. Risperidone was well absorbed. Maximum plasma concentrations were reached at 0.5–1 h after subcutaneous administration. Plasma concentrations of 9-hydroxy-risperidone were higher than those of risperidone from 2 h after dosing. In plasma, the apparent elimination half-life of risperidone was 1.0 h, and mean residence times were 1.5 h for risperidone and 2.5 h for its 9-hydroxy metabolite. Plasma levels of the radioactivity increased dose proportionally between 0.02 and 1.3 mg/kg. Risperidone was rapidly distributed to brain tissues. The elimination of the radioactivity from the frontal cortex and striatum—brain regions with high concentrations of 5-HT2 or dopamine-D2 receptors—became more gradual with decreasing dose levels. After a subcutaneous dose of 0.02 mg/kg, the ED50 for central 5-HT2 antagonism in male rats, half-lives in frontal cortex and striatum were 3–4 h for risperidone, whereas mean residence times were 4–6 h for risperidone and about 12 h for 9-hydroxy-risperidone. These half-lives and mean residence times were 3–5 times longer than in plasma and in cerebellum, a region with very low concentrations of 5-HT2 and D2 receptors. Frontal cortex and striatum to plasma concentration ratios increased during the experiment. The distribution of 9-hydroxy-risperidone to the different brain regions, including frontal cortex and striatum, was more limited than that of risperidone itself. This indicated that 9-hydroxy-risperidone contributes to the in vivo activity of risperidone, but to a smaller extent than would be predicted from plasma levels. AUCs of both active compounds in frontal cortex and striatum were 10–18 times higher than those in cerebellum. No retention of metabolites other than 9-hydroxy-risperidone was observed in any of the brain regions investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245444
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  • 115
    Electronic Resource
    Electronic Resource
    Discriminative stimulus properties of cocaine: modulation by dopamine D1 receptors in the nucleus accumbens (1994)
    Springer
    Psychopharmacology 115 (1994), S. 110-114 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Drug discrimination ; Nucleus accumbens ; Dopamine D1 and D2 receptors ; Microinjection ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dopamine (DA) D1 and D2 receptors are involved in mediating the behavioral effects of cocaine, including its discriminative stimulus properties. The purpose of the present study was to investigate the role of the nucleus accumbens and, in particular, accum bens DA D1 receptors in modulating the stimulus effects of cocaine. Thus, rats were trained to discriminate cocaine (10 mg/kg, IP) from saline using a two-lever, water-reinforced FR 20 drug discrimination task. In substitution tests, systemic (IP) administration of cocaine (0.625–20 mg/kg) produced a dose-related increase in cocaine-appropriate responding. Microinjections of cocaine (2.5–40 µg) into the nucleus accumbens also engendered dose-dependent and complete substitutions (〉 80% drug-lever responding) for the systemic training dose of cocaine, whereas intra-accumbens artificial cerebrospinal fluid (1 µl/side) produced primarily saline-appropriate responding. In antagonism tests, pretreatment with the DA D1 antagonist SCH 23390 (3–12 µg/kg) completely antagonized (〈20% drug-lever responding) a dose of cocaine (5 mg/kg) that produced greater than 90% cocaine-lever responding when given alone. Additionally, intra-accumbens injections of SCH 23390 (0.025–0.4 µg) prior to systemic cocaine (5 mg/kg) also significantly blocked the cocaine stimulus. The present results confirm the importance of the nucleus accumbens in mediating the discriminative stimulus properties of cocaine and suggest a primary role of accumbens DA D1 receptors in modulating this behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244759
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    Evaluation of the discriminative stimulus effects of the novel sedative-hypnotic CL 284,846 (1994)
    Springer
    Psychopharmacology 115 (1994), S. 289-296 
    Details
    ISSN: 1432-2072
    Keywords: CL 284,846 ; Drug discrimination ; Sedative ; Hypnotic ; Anxiolytic ; Rat ; Benzodiazepine receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract CL 284,846,N-[3-(3-cyanopyrazolo[1, 5-a]pyrimidin-7-yl)phenyl)]-N-ethylacetamide, is a novel non-benzodiazepine sedative-hypnotic with benzodiazepine-like sedative effects, but with less apparent liability for accompanying undesired side effects. In an effort to further characterize its pharmacological activity, CL 284,846 (3.0 mg/kg, IP, 30 min pretreatment) was established as a discriminative stimulus (DS) in rats (n=7). CL 284,846 (0.3–10.0 mg/kg) showed a dose-related increase in drug-appropriate responding up to the training dose and a dose-related decrease in response rate. The benzodiazepine agonist triazolam (0.1–1.0 mg/kg), the benzodiazepine partial agonist Ro 17-1812 (0.3–3.0 mg/kg) and the triazolopyridazine CL 218,872 (1.0–3.0 mg/kg) substituted for CL 284,846 in all rats, whereas the imidazopyridines zolpidem (3.0–10.0 mg/kg) and alpidem (10.0–30.0 mg/kg), the benzodiazepine partial agonist bretazenil (0.03–10.0 mg/kg) and the novel putative anxiolytic CL 273,547 (10.0–56.0 mg/kg) substituted in most, but not all, rats. Ro 17-1812, bretazenil, and CL 218,872 had no effect on response rate while the other drugs showed a concomitant decrease in rate. The 5-HT1A agonist buspirone (1.0–10.0 mg/kg) and the barbiturate pentobarbital (3.0–17.0 mg/kg) failed to substitute for CL 284,846 up to rate-decreasing doses. The benzodiazepine antagonist flumazenil (3.0–10.0 mg/kg) blocked the DS effects of CL 284,846 in most rats with no effect on response rate. Taken together, these results suggest that the DS effects of CL 284,846 are mediated via benzodiazepine receptors; however, the DS profile of CL 284,846 remains distinct from both benzodiazepine and non-benzodiazepine sedative-hypnotic drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245068
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    Caffeine augmentation of electroconvulsive seizures (1994)
    Springer
    Psychopharmacology 115 (1994), S. 320-324 
    Details
    ISSN: 1432-2072
    Keywords: Caffeine ; Electroconvulsive shock ; Seizure ; Rat ; Electroencephalography ; Convulsions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Caffeine has been used clinically to increase seizure length in electroconvulsive treatment (ECT). The present study was designed to establish an animal model of caffeine-augmented seizures for further study of mechanisms and effects of pharmacological manipulation of seizure length. Increasing doses of caffeine (0–200 mg/kg, IP) were given before electroconvulsive stimulation (ECS) in rats and resulting seizure lengths were quantified by timing of classical tonic-clonic convulsive movements. With this paradigm, caffeine led to a dose-dependent increase in seizure duration. This proconvulsant action of caffeine was detectable within 1 min after dosing, persisted for at least 230 min and was reversible. The results suggest that seizure length is a practicable measure in pharmacological modification of electroconvulsive seizures. They also suggest that pharmacologically-modified ECS can be modeled effectively in animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245072
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    Effects of GABA-ergic drugs on penile erection induced by apomorphine in rats (1994)
    Springer
    Psychopharmacology 115 (1994), S. 249-253 
    Details
    ISSN: 1432-2072
    Keywords: Penile erection ; Muscimol ; Baclofen ; Bicuculline ; Picrotoxin ; Phaclofen ; Apomorphine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of GABA agonists and antagonists on penile erection (PE) induced by apomorphine were investigated in rats. Subcutaneous (SC) administration of apomorphine (0.01–0.1 mg/kg) induces a dose-dependent PE in rats. The maximum effect was obtained with 0.1 mg/kg of the drug. The response was decreased with increasing doses of apomorphine from 0.1 to 0.5 mg/kg. The response induced by apomorphine (0.1–0.5 mg/kg) was decreased in animals pretreated with either the GABA-A agonist muscimol or the GABA-B agonist baclofen. Combination of muscimol with baclofen caused a stronger inhibitory effect on apomorphine-induced PE. Bicuculline or picrotoxin but not phaclofen reduced the inhibitory effect of muscimol on PE induced by apomorphine, whereas phaclofen but not GABA-A antagonists decreased the inhibitory action of baclofen on apomorphine-induced PE. Pretreatment of animals with higher doses of the GABA-A antagonists bicuculline and picrotoxin or the GABA-B antagonist phaclofen elicited inhibition of apomorphine-induced PE. However, the inhibitory effects of GABA-A and GABA-B antagonists are lost on combination. Administration of GABA-A and GABA-B receptor stimulation inhibit PE induced by dopaminergic mechanism(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244779
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    Microcatalepsy and disruption of forelimb usage during operant behavior: differences between dopamine D1 (SCH-23390) and D2 (raclopride) antagonists (1994)
    Springer
    Psychopharmacology 115 (1994), S. 24-30 
    Details
    ISSN: 1432-2072
    Keywords: Dopamine receptors ; Neuroleptics ; SCH-23390 ; Raclopride ; Response duration ; Catalepsy ; Operant behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In an experiment designed to distinguish between the behavioral consequences of treatment with SCH-23390, a D1 dopamine receptor blocker, and raclopride, a D2 antagonist, rats were trained to perform a water-reinforced forelimb operant response. Response rate and the duration of each forelimb contact with the operandum were recorded. In addition, the durations of the rat's visits to the reward well were detected by a photobeam which was blocked by the rat's muzzle as it remained at the reward well. In a between-groups dosing design, separate groups of rats (11–13 rats/group) received SCH-23390 (0, 0.01, 0.02, 0.04, 0.08, 0.12 mg/kg, IP, 30 min) or raclopride (0. 0.05, 0.1, 0.2, 0.4, 0.8 mg/kg, IP, 30 min) for 21 consecutive days. Quantitative analyses indicated that for comparable amounts of operant rate reduction, raclopride had a significantly greater tendency than SCH-23390 to increase the duration of operant responses and to increase the maximum muzzle entry duration (i.e., to induce microcatalepsy). The results support the idea that at relatively low doses D2 antagonism is more likely than D1 antagonism to produce effects identified preclinically with extrapyramidal side effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244747
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    Effects of cocaine microinjections into the nucleus accumbens and medial prefrontal cortex on schedule-induced behaviour: comparison with systemic cocaine administration (1994)
    Springer
    Psychopharmacology 115 (1994), S. 375-382 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Schedule-induced polydipsia ; Drinking ; Locomotor activity ; Nucleus accumbens ; Medial prefrontal cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of cocaine HCl infusions into either the nucleus accumbens (NACC) or medial prefrontal cortex (PFC) were compared on the performance of schedule-induced polydipsia (SIP) and related behaviours. Food-deprived rats were exposed to a fixed-time 60-s schedule of food delivery in daily 30-min sessions until stable levels of behaviour were obtained (14 days). Rats were then bilaterally infused with cocaine into either the NACC or PFC via chronically indwelling guide cannulae. Each subject received a sequence of five cocaine infusions (0, 12.5, 25, 50, 100 µg) according to a Latin Square design. For comparison, following these intracranial infusions each rat received a sequence of five IP injections of cocaine (0, 2.5, 5, 10, 20 mg/kg) also in a counterbalanced order. NACC and PFC infusions of cocaine and IP cocaine dose-dependently reduced SIP. Cocaine infusions into the NACC, but not the PFC, increased locomotor activity but the characteristic temporal profile of locomotor activity during SIP was retained. IP cocaine also increased locomotor activity in a dose-dependent manner, but the temporal profile of activity was flattened following 20 mg/kg cocaine. NACC and PFC infusions of cocaine had little effect on the total number of panel presses to gain access to the food pellets, but did slightly decrease the high rates of responding immediately prior to the pellet delivery. IP cocaine increased the total number of panel presses at the higher doses, mainly by increasing the low rates of responding. The effects of cocaine infusions into the PFC were behaviourally the most selective, as they reduced SIP without having substantial effects either on locomotor activity or panel pressing. These data therefore implicate a role for the PFC in the performance of SIP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245080
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    Behavioural and pharmacological characterisation of the elevated “zero-maze” as an animal model of anxiety (1994)
    Springer
    Psychopharmacology 116 (1994), S. 56-64 
    Details
    ISSN: 1432-2072
    Keywords: Anxiety ; Elevated zero-maze ; Rat ; Diazepam ; Chlordiazepoxide ; mCPP ; 8-OH-DPAT ; Ondansetron ; Head dips ; Stretched attend postures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The elevated “zero-maze” is a modification of the elevated plus-maze model of anxiety in rats which incorporates both traditional and novel ethological measures in the analysis of drug effects. The novel design comprises an elevated annular platform with two opposite enclosed quadrants and two open, removing any ambiguity in interpretation of time spent on the central square of the traditional design and allowing uninterrupted exploration. Using this model, the reference benzodiazepine anxiolytics, diazepam (0.125–0.5 mg/kg) and chlordiazepoxide (0.5–2.0 mg/kg) significantly increased the percentage of time spent in the open quadrants (% TO) and the frequency of head dips over the edge of the platform (HDIPS), and reduced the frequency of stretched attend postures (SAP) from the closed to open quadrants. In contrast, the anxiogenic drugm-chlorophenyl-piperazine (mCPP; 0.25–1.0 mg/kg) induced the opposite effects, decreasing %TO and HDIPS, and increasing SAP. The 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.001–0.1 mg/kg) had no effects on either %TO or HDIPS, but did decrease SAP at 0.01 mg/kg although not at higher or lower doses. Similarly, the 5-HT3 receptor antagonist, ondansetron (0.0001–1.0 mg/kg) decreased SAP and increased %TO at 0.01 mg/kg, but not at other doses. The present data suggest that a combination of the novel “zero-maze” design and a detailed ethological analysis provides a sensitive model for the detection of anxiolytic/anxiogenic drug action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244871
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    An examination of the behavioural specificity of hypophagia induced by 5-HT1B, 5-HT1C and 5-HT2 receptor agonists using the post-prandial satiety sequence in rats (1994)
    Springer
    Psychopharmacology 113 (1994), S. 369-377 
    Details
    ISSN: 1432-2072
    Keywords: 5-HT1B ; 5-HT1C ; 5-HT2 receptors ; Feeding ; Satiety sequence ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Previous studies have shown that administration of 5-HT1B, 5-HT1C or 5-HT2 agonists decreases food intake in rats. However, it has not been established whether these drugs induce satiety or decrease feeding by a non-specific mechanism. In the present study the post-prandial satiety sequence was used to characterise the actions of the 5-HT2 receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), the 5-HT1B/5-HT1C receptor agonists, 1-(3-chorophenyl) piperazine (mCPP) and 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), and the 5-HT1B agonist, 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)H-indole (RU 24969), on feeding in rats. All four compounds reduced food intake in rats that had been food deprived overnight. The 5-HT1B/5-HT1C agonists, TFMPP (at a dose of 1.0 mg/kg) and mCPP (at a dose of 3.0 mg/kg), appeared to produce satiety as their effects on the satiety sequence were similar to those induced by a food pre-load. In contrast, the 5-HT1B agonist RU 24969 and the 5-HT2 agonist DOI did not produce behavioural profiles that resembled satiety. Thus, RU 24969 elevated active behaviours and did not accelerate resting whereas DOI appeared to induce hypophagia by a non-specific fragmentation of behaviour. The results suggest that simultaneous activation of 5-HT1B and 5-HT1C receptors may be sufficient to elicit behaviourally specific satiety in the rat. In contrast, selective activation of 5-HT2 receptors does not induce satiety but elicits active behaviours and decreases feeding by response competition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245211
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    Ontogeny of behavioral sensitization in the rat: effects of direct and indirect dopamine agonists (1994)
    Springer
    Psychopharmacology 116 (1994), S. 483-490 
    Details
    ISSN: 1432-2072
    Keywords: Behavioral sensitization ; amphetamine ; NPA ; Ontogeny ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present study, the abilities of NPA (a direct DA receptor agonist) and amphetamine (an indirect DA receptor agonist) to induce short- and long-term behavioral sensitization were assessed in 11- and 17-day-old rats (age at initial injection). Rats were injected on 4 consecutive days with amphetamine (1.0, 2.5, or 5.0 mg/kg), NPA (1.0 mg/kg), or saline. A final test day occurred either 2 days (experiment 1) or 8 days (experiment 2) later. On the test day, rats given successive agonist injections received a single injection of the same agonist again; whereas rats given successive saline injections received either amphetamine or NPA for the first time. Five minutes after injection, locomotor activity (line-crosses), stereotyped sniffing, and vertical activity were measured during a 30-min testing session. The results showed that 11- and 17-day-old rats exhibited behavioral sensitization when tested with NPA or amphetamine after a 2-day interval. In contrast, neither NPA nor amphetamine was able to sensitize the behaviors of preweanling rats when measured 8 days after initial drug treatments. Therefore, these results show that both direct and indirect DA agonists are able to induce short-term behavioral sensitization in preweanling rats, but that the mechanisms responsible for mediating long-term behavioral sensitization have not yet matured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247482
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    Stress-induced changes in respiratory quotient, energy expenditure and locomotor activity in rats: effects of midazolam (1994)
    Springer
    Psychopharmacology 116 (1994), S. 475-482 
    Details
    ISSN: 1432-2072
    Keywords: Stress ; Anxiety ; Rat ; Metabolism ; Energy expenditure ; Energy substrate utilisation ; Respiratory quotient ; Midazolam ; FG-7142 ; RO 15-1788 ; Panic ; Hyperventilation ; Sympathetic nervous system ; Benzodiazepine ; Conditioned stimulus ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in O2 consumption, CO2 production and locomotor activity were examined in rats exposed to (1) brief footshock, (2) an aversive conditioned stimulus (CS) predicting footshock, or (3) the anxiogenic drug FG-7142. Respiratory quotient (RQ=CO2 produced/O2 consumed) and energy expenditure [EE=O2 consumed (364+113RQ)] were derived to give an estimate of the energy substrate (fat, carbohydrate or protein) being utilised and total substrate oxidation respectively. In experiment 1, footshock (4 × 5 s 0.6 mA shocks over 2 min) produced an immediate increase in RQ, EE and activity. The RQ and EE effects were attenuated by the benzodiazepine midazolam (1 mg/kg). In experiment 2, an aversive CS, consisting of flashing light and buzzer that had 24 h earlier been repeatedly paired with footshock (20 × 5 s 0.6 mA shocks) caused a pronounced drop in RQ, an increase in EE and locomotor activity suppression. The effects of the aversive CS on RQ and EE were reversed by midazolam (1 mg/kg). In experiment 3, FG-7142 (10 mg/kg) produced a steep drop in RQ that persisted for at least 2 h and which was reversed by midazolam (1 mg/kg) and delayed by the benzodiazepine antagonist RO 15-1788 (10 mg/kg). FG-7142 also tended to inhibit EE and locomotor activity, but these effects did not reach statistical significance. Overall, these data show that stress causes profound alterations in RQ, EE and activity and that the pattern of change in these parameters differs with the nature of the stressor involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247481
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    Kavapyrone enriched extract fromPiper methysticum as modulator of the GABA binding site in different regions of rat brain (1994)
    Springer
    Psychopharmacology 116 (1994), S. 469-474 
    Details
    ISSN: 1432-2072
    Keywords: Kavapyrone ; Piper methysticum ; GABA ; Rat ; Brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Regional differences in the modulation of [3H] muscimol binding to GABAA receptor complexes by kavapyrones, compounds of the rhizome of the plantPiper methysticum which possess sedative activity, were demonstrated using membrane fractions obtained from target brain centers of kavapyrone action: hippocampus (HIP), amygdala (AMY) and medulla oblongata (MED), and from brain centers outside the main kavapyrone effects as frontal cortex (FC) and cerebellum (CER). The kava extract enhanced the binding of [3H] muscimol in a concentration-dependent manner with maximal potentiation of 358% over control in HIP followed by AMY and MED (main target brain centers). Minimal stimulation was observed in CER followed by FC. In contrast, apart from CER, the potency of kavapyrones was similar in the brain areas investigated with EC50 values ranging between 200 and 300 µM kavapyrones. Scatchard analysis revealed that the observed effects of kavapyrones were due to an increase in the number of binding sites (Bmax), rather than to a change in affinity. At a kavapyrone concentration of 500 µM the order of enhancement in Bmax was HIP=AMY〉MED〉FC〉CER. When kavapyrones are included together with pentobarbital or HPO the two classes of compounds produced a more than additive, i.e., synergetic effect on [3H] muscimol binding. Our findings suggest that one way kavapyrones might mediate sedative effects in vivo is through effects on GABAA receptor binding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247480
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    Prenatal nicotine exposure increased duration of nicotine-induced analgesia in adult rats (1994)
    Springer
    Psychopharmacology 113 (1994), S. 534-538 
    Details
    ISSN: 1432-2072
    Keywords: Nicotine ; Prenatal ; Analgesia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of prenatal exposure to nicotine on nicotine-induced analgesia was studied in rats. The analgesic effect of a single dose of nicotine (1 mg/kg SC) was measured by the tail-flick technique, and two subsequent studies were carried out. In the first study, 7-month-old male rats, born to dams chronically treated with nicotine during pregnancy (NIC), exhibited prolonged nicotine-induced analgesia compared to matched controls. The second study was designed to explore whether rats prenatally exposed to nicotine (NIC rats) are born with an increased sensitivity to nicotine and whether there is any sex difference. The analgesic effect of nicotine was tested on control and NIC rats of both sexes once a month from 2 to 7 months of age. At an early age, male but not female NIC rats, exhibited shorter analgesic responses to nicotine than did the matched controls. With increasing age, however, the duration of nicotine analgesia began to be prolonged in NIC rats of both sexes. Significant differences between control and NIC rats were found at the age of 6 and 7 months, in both sexes. Thus, rats prenatally exposed to nicotine are not born with an increased sensitivity to the analgesic effect of a single dose of nicotine. This phenomenon develops later, during the course of life, independently of gender.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245235
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    Effect of lesions of the ascending 5-hydroxytryptaminergic pathways on timing behaviour investigated with the fixed-interval peak procedure (1994)
    Springer
    Psychopharmacology 114 (1994), S. 463-468 
    Details
    ISSN: 1432-2072
    Keywords: 5-Hydroxytryptamine ; 5,7-Dihydroxytryptamine ; Operant behaviour ; Timing ; Fixed-interval peak procedure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Twelve rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei; 12 rats received sham lesions. The rats were then trained for 60 sessions under a discrete-trials fixed-interval schedule (peak procedure). In half the trials, a reinforcer became available 40 s after trial onset, and the trial was terminated upon reinforcer delivery; the remaining trials were 120 s in duration, and reinforcement did not occur in these trials. Performance during the 120-s trials was characterized by increasing response rate during the first 40 s of the trial, declining response rate between 40 s and 80 s, and a secondary increase in response rate during the final 40 s of the trial. The lesioned group showed a broader “spread” of the response rate function than the control group (time between attainment of 70% of the peak response rate and subsequent decline of response rate below this level); however, the peak response rate and the time from trial onset until attainment of the peak response rate did not differ significantly between the groups; the spread/peak-time ratio was significantly greater in the lesioned group than in the control group. The levels of 5-hydroxytryptamine (5HT) and 5-hydroxyindoleacetic acid in the parietal cortex, hippocampus, amygdala, nucleus accumbens and hypothalamus were markedly reduced in the lesioned group, but the levels of noradrenaline and dopamine were not significantly affected by the lesion. The results confirm the involvement of 5HTergic function in timing behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02249337
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    Methamphetamine exposure during early postnatal development in rats: I. Acoustic startle augmentation and spatial learning deficits (1994)
    Springer
    Psychopharmacology 114 (1994), S. 392-401 
    Details
    ISSN: 1432-2072
    Keywords: Methamphetamine ; Rat ; Postnatal ; Acoustic startle ; Spatial learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methamphetamine (MA) induces neurotransmitter reductions and neurotoxicity at high doses in adult animals, but its effects on early brain development and behavior have received less attention. In this experiment the effects of MA exposure during a period equivalent to the human third trimester were examined. Rats (Sprague-Dawley CD) were injected subcutaneously withd-MA (30 mg/kg b.i.d.) early in postnatal development (days 1–10), later (postnatal days 11–20), or with water during both of these periods. Both early and later MA-exposed offspring exhibited augmented acoustic startle and impaired performance in a complex multiple-T water maze. Only the early MA exposure group showed a persistent deficit in weight while only the later MA exposure group showed impaired learning in the Morris hidden platform maze. Effects on locomoter activity are reported in the accompanying article. It was concluded that the effects of MA are both long lasting and stage dependent and involve cognitive as well as arousal functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02249328
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    Effects of chronic phenylpropanolamine infusion and termination on body weight, food consumption and water consumption in rats (1994)
    Springer
    Psychopharmacology 114 (1994), S. 513-519 
    Details
    ISSN: 1432-2072
    Keywords: Phenylpropanolamine ; Body weight ; Food consumption ; Water consumption ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study determined the effect of chronic PPA infusion and withdrawal on weight regulation. Male Sprague-Dawley rats received PPA (0, 90 or 180 mg/kg) via miniosmotic pumps for 2 weeks. Body weight and food and water consumption were measured daily before, during, and for 2 weeks after PPA infusion. Additionally, body weight was measured once 6 weeks after the last day of drug administration. PPA infusion produced dose-dependent reductions in body weight and food consumption throughout drug administration. During the first week of PPA termination, food consumption returned to control levels; however, body weights of drug-treated animals remained below those of controls throughout the 6-week post-drug period. PPA depressed water intake during the first week of drug administration, but tolerance to this effect developed by the second week of administration. These results suggest chronic PPA infusion produces persistent appetite suppression and weight loss and that discontinuation of PPA does not result in hyperphagia or rapid weight gain. These findings may have clinical significance for the many individuals who wish to lose weight but have difficulty reducing intake without pharmacologic assistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02249344
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    Diazepam impairs place learning in naive but not in maze-experienced rats in the Morris water maze (1994)
    Springer
    Psychopharmacology 115 (1994), S. 73-78 
    Details
    ISSN: 1432-2072
    Keywords: Benzodiazepines ; Diazepam ; Morris water maze ; Place learning ; Anxiety ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Anxiolytic benzodiazepines have been shown to impair place learning in the Morris water maze. However, a clear-cut demonstration of a direct and specific effect on mnemonic processes has not yet been offered. In the present study, the effects of diazepam on place navigation in the Morris water maze were studied in rats. Three conditions were examined: learning, reversal learning and learning after familiarisation of animals with the maze. In view of the anxiolytic and sedative properties of diazepam, appropriate doses of the drug, i.e. those that produced an anxiolytic effect but no major motor impairment, were initially selected in the water-lick conflict and rotarod tests, respectively. Doses of 2.5 and 5 mg/kg PO increased punished drinking in the water-lick conflict test without significantly decreasing rotarod performance. These doses were then used to assess the effects of diazepam on spatial behaviour. Diazepam, at both doses, impaired place learning in behaviourally naive rats. Such an effect appeared to be transient: diazepam-treated rats eventually reached control performance. Moreover, analysis of the probe trial at the end of training revealed adoption of a spatial strategy to locate the submerged platform. Neither reversal learning nor learning after familiarisation was affected. These results do not replicate previous findings in the Morris water maze and provide some evidence that the diazepam-induced place learning deficit may be primarily anxiolytic in nature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02244754
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    α2-adrenoceptor blockade, pituitary-adrenal hormones, and agonistic interactions in rats (1994)
    Springer
    Psychopharmacology 115 (1994), S. 478-484 
    Details
    ISSN: 1432-2072
    Keywords: Aggression ; α2 Adrenoceptors ; Catecholamines ; ACTH ; Corticosterone ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of adrenergic activation on aggressiveness and the aggression induced endocrine changes were tested in rats. α2 adrenoceptor blockers were used for enhancing activation of the adrenergic system, and changes in aggressiveness were tested in resident-intruder contests. Three experiments were conducted. In experiment 1, saline injected rats responded to the presence of an opponent by aggression and the increase in plasma ACTH and corticosterone. Intraperitoneal administration of 1 mg/kg CH-38083 (an α2 adrenoceptor antagonist) produced a several fold increase in clinch fighting and mutual upright scores, and also further enhanced the plasma ACTH and corticosterone response. In experiment 2, the effect of three doses (0.5, 1 and 2 mg/kg) of three different α2 adrenoceptor blockers CH-38083, idazoxan and yohimbine were tested. All the substances increased aggression at 0.5 and 1 mg/kg; at 2 mg/kg the effect of idazoxan and yohimbine disappeared, while with CH-38083 an additional increase was obtained. In yohimbine treated animals the enhancement of aggression was reduced already at 1 mg/kg. In experiment 3, indomethacin, a potent inhibitor of the catecholamine-induced ACTH release completely abolished the effects of the α2 adrenoceptor antagonist CH-38083: the intensity of agonistic interactions, as well as ACTH and corticosterone plasma concentrations, returned to control levels. The possible role of catecholamines and the stress hormones in the activation of aggression is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245571
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  • 132
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    Evidence for altered α2-adrenoceptor function following isolation-rearing in the rat (1994)
    Springer
    Psychopharmacology 116 (1994), S. 183-190 
    Details
    ISSN: 1432-2072
    Keywords: Isolation rearing ; α2-Adrenoceptor ; Clonidine ; Mydriasis ; Hypoactivity ; [3H]-Idazoxan binding ; cAMP ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study investigated central α2-adrenoceptor function in differentially reared rats. Rats reared from weaning were either housed singly or in groups of five. Measurements of spontaneous ambulatory activity at 4 weeks postweaning showed that isolates were more hyperactive on exposure to a novel environment than grouped rats. α2-Adrenoceptors were investigated using α2-adrenoceptor agonist-induced behaviours, [3H]-idazoxan binding and measurement of forskolin-stimulated cyclic AMP accumulation. Clonidine (0.001–1.0 mg/kg IP) induced mydriasis in both groups with no difference observed in the response between the isolation and group-reared animals. Clonidine (0.01–0.5 mg/kg IP) induced hypoactivity in both groups, with the effect significantly greater in the isolation-reared rats. Idazoxan markedly attenuated both responses, confirming their induction by α2-adrenoceptor stimulation. Clonidine-induced hypoactivity and mydriasis are mediated by pre- and postsynaptic α2-adrenoceptors, respectively; therefore the results suggest rats reared in isolation have enhanced presynaptic but unchanged postsynaptic α2-adrenoceptor function. Saturation binding experiments using [3H]-idazoxan were undertaken to determine α2-adrenoceptor number (Bmax) and affinity (Kd) in membranes prepared from the frontal cortex and hippocampus. Analysis of binding data revealed an increase in receptor number in the hippocampus of isolates. Cyclic AMP accumulation was measured in hippocampal slices from differentially reared rats. Isolation-rearing did not affect cyclic AMP accumulation in response to stimulation by forskolin (30 µM). However, the selective α2-adrenoceptor agonist, UK14304, produced a significantly greater inhibition of cyclic AMP accumulation in slices from isolated rats, confirming changes in α2-adrenoceptor function following isolation rearing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245061
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    Effects of SR 48692, a selective non-peptide neurotensin receptor antagonist, on two dopamine-dependent behavioural responses in mice and rats (1994)
    Springer
    Psychopharmacology 116 (1994), S. 237-241 
    Details
    ISSN: 1432-2072
    Keywords: SR 48692 ; Neurotensin receptor antagonist ; Dopamine ; Apomorphine ; Bromocriptine ; (+) SKF 38393 ; (+) Amphetamine ; Turning ; Yawning ; Mouse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract One major mechanism underlying the central action of neurotensin is an interaction with the function of dopamine (DA)-containing neurons. In addition, direct or indirect DA agonists have been reported to promote neurotensin release. We have found that SR 48692, a non-peptide neurotensin receptor antagonist (0.04 – 0.64 mg/kg orally), antagonizes (50–65%) yawning induced by apomorphine (0.07 mg/kg SC) or bromocriptine (2 mg/kg IP) in rats, and turning behaviour induced by intrastriatal injection of apomorphine (0.25 µg), (+) SKF 38393 (0.1 µg), bromocriptine (0.01 ng) or (+) amphetamine (10 µg) in mice. Other apomorphine-induced effects in mice and rats such as climbing, hypothermia, hypo- and hyper-locomotion, penile erections and stereotypies were not significantly modified by SR 48692. Taken together, these data suggest that neurotensin may play a permissive role in the expression of some but not all behavioural responses to DA receptor stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245067
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  • 134
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    Atropine effects on the intermediate stage and paradoxical sleep in rats (1994)
    Springer
    Psychopharmacology 116 (1994), S. 304-308 
    Details
    ISSN: 1432-2072
    Keywords: Intermediate stage of sleep ; Paradoxical sleep ; Spindle ; Theta rhythm ; Atropine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Paradoxical sleep (PS) in the rat, cat and mouse is preceded and sometimes followed by a short-lasting intermediate stage (IS) characterized by high amplitude cortical spindles and low frequency theta rhythm. This stage, which is mimicked by an intercollicular transection, is massively extended at the expense of PS by low doses of barbiturates. Since the pontine cholinergic cell activation of PS is suppressed by barbiturates, we studied whether atropine, an antimuscarinic compound, extends IS at the expense of PS. Atropine sulfate was given at 5, 10 and 20 mg/kg IP. All doses increased dose dependently the occurrence latency of IS and PS. The amount of IS and PS was decreased for several hours, principally by a decrease of the number of phases. At 20 mg/kg the phase mean duration of IS and PS was also decreased. Consequently, IS and PS are similarly supported by muscarinic processes. The theta rhythm frequency was scored during IS and outside PS phasic motor activities (type 2 theta). At all doses it was significantly increased for hours. The theta rhythm frequency was also transiently increased during the hypersynchronization periods of PS (type 1 theta). At 20 mg/kg it was similarly the case for type 1 theta rhythm during waking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245333
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    Stereospecific reversal of stress-induced anhedonia by mianserin and its (+)-enantiomer (1994)
    Springer
    Psychopharmacology 116 (1994), S. 523-528 
    Details
    ISSN: 1432-2072
    Keywords: Chronic mild stress ; Anhedonia ; Sucrose drinking ; Place conditioning ; Mianserin ; (+)-Mianserin ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic sequential exposure to a variety of mild unpredictable stressors has previously been found to depress the consumption of a dilute (1%) sucrose solution and to inhibit food-induced place preference conditioning. In the present study, using a simplified version of the mild stress procedure, the decreased sucrose intake was reversed by chronic (4 weeks) treatment with the atypical antidepressant mianserin. The racemic compound (±)-mianserin (5 mg/kg per day) and one of its enantiomers, (+)-mianserin (2.5 mg/kg) were effective in this model; a lower dose of (±)-mianserin (2.5 mg/kg), and the other enantiomer, (−)-mianserin (2.5 mg/kg), were ineffective. Vehicle-treated stressed animals were also subsensitive to food reward in the place conditioning procedure: normal place preference conditioning was reinstated by chronic treatment with (±)-mianserin (5 mg/kg) or (+)-mianserin, but not by the lower dose of (±)-mianserin (2.5 mg/kg) or by (−)-mianserin. Raclopride (100 µg/kg) reinstated the decrease in sucrose intake in stressed animals successfully treated with (±)- or (+)-mianserin. The results suggest that (+)-mianserin is the active enantiomer in reversing chronic mild stress-induced anhedonia, and further support the hypothesis of a dopaminergic mechanism of antidepressant action in this paradigm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247488
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    Methamphetamine exposure during early postnatal development in rats: II. Hypoactivity and altered responses to pharmacological challenge (1994)
    Springer
    Psychopharmacology 114 (1994), S. 402-408 
    Details
    ISSN: 1432-2072
    Keywords: Methamphetamine ; Rat ; Postnatal development ; Hypoactivity ; Pharmacological challenge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methamphetamine induces neurotransmitter reductions and neurotoxicity at high doses in adult animals, but its effects on early brain development and behavior have received little attention. In this experiment the effects of methamphetamine exposure during a period equivalent to the human third trimester were examined. Rats (Sprague-Dawley CD) were injected subcutaneously withd-methamphetamine (d-MA) (30 mg/kg b.i.d.) early in postnatal development (days 1–10), later (postnatal days 11–20), or with water during both of these periods. Both early and later MA-exposed offspring exhibited reduced locomotor activity. The effect was most evident at 30 days of age and was smaller at 45 and 60 days and only present at these latter ages in males. Only the early MA exposure group showed prolonged suppression of activity in response to a challenge dose of fluoxetine and a persistant deficit in weight while only the later MA exposure group showed attenuated suppression of activity in response to a challenge dose of fluoxetine. Based both on the present data and those in the preceding article, it was concluded that the effects of MA are both long lasting and stage dependent and involve arousal as well as cognitive functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02249329
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    Effects of the calcium antagonist isradipine on cocaine intravenous self-administration in rats (1994)
    Springer
    Psychopharmacology 113 (1994), S. 378-380 
    Details
    ISSN: 1432-2072
    Keywords: Cocaine ; Self-administration ; Calcium antagonists ; Isradipine ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of isradipine, a dihydropyridine calcium antagonist, on cocaine intravenous self-administration in rats was investigated. Administration of (±)isradipine (1.25–5 mg/kg SC) 2 h before the cocaine self-administration session induced a significant and dose-dependent increase in the number of coacine injections with respect to basal values. This effect was sterospecific, with the (+) form of isradipine being active, while the (−) stereoisomer was ineffective. These results suggest that isradipine antagonizes the rewarding properties of cocaine, possibly by inhibiting those dopaminergic systems related to reward mechanisms. These results further indicate a possible use of isradipine, or structurally similar compounds, in the treatment of cocaine related disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245212
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    Alterations in the ontogeny of rat pup ultrasonic vocalization produced by prenatal exposure to nitrogen dioxide (1994)
    Springer
    Psychopharmacology 116 (1994), S. 423-427 
    Details
    ISSN: 1432-2072
    Keywords: Nitrogen dioxide ; Prenatal exposure ; Behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Wistar female rats were exposed to low concentrations of nitrogen dioxide, NO2 (1.5 and 3 ppm) from day 0 to day 20 of pregnancy. The results show that prenatal exposure to this oxidant gas produced significant changes in the duration pattern of ultrasonic vocalizations emitted by male pups removed from their nest. In particular, a significant decrease in the length of ultrasonic calls was found in both 10- and 15-day-old rats exposed to NO2 (3 ppm) during gestation. These alterations were found at dose levels which did not significantly affect reproduction parameters, body weight gain and motor activity development. These findings suggest that gestational exposure to NO2, at concentrations below those associated with overt signs of toxicity, induces in rat offspring subtle behavioral changes characterized by altered ontogeny of ultrasonic emission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247472
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  • 139
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    Dissociation between brown adipose tissue thermogenesis and sympathetic activity in rats with high plasma levels of oestradiol (1994)
    Springer
    Pflügers Archiv 426 (1994), S. 40-43 
    Details
    ISSN: 1432-2013
    Keywords: Brown adipose tissue ; Cold-acclimation ; Noradrenaline turnover ; Oestradiol ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been shown previously that high plasma levels of oestradiol inhibit brown adipose tissue thermogenesis. Since rats and mice show a close association between thermogenic activity in and sympathetic discharge to brown fat, we measured the noradrenaline turnover in rats with high plasma levels of oestradiol to establish whether the observed inhibition of thermogenic activity is brought about by a reduction in the sympathetic drive to brown adipocytes. Oestradiol-filled Silastic capsules were implanted subcutaneously in female rats previously acclimated either to thermoneutrality or to cold. Control rats received empty implants. After 15 days treatment, noradrenaline turnover was measured by blocking its synthesis with α-methyl-p-tyrosine. As expected, noradrenaline turnover was higher in cold-acclimated rats than in rats kept at thermoneutrality. The presence of high plasma oestradiol levels did not alter sympathetic activity in any of the treated groups despite reducing thermogenic activity. This result reveals that oestradiol dissociates the thermogenic activity of brown adipose tissue from its sympathetic activation. Such dissociation has never been previously reported in rats, although it seems to be common in Syrian hamsters. However the causative factor in this species is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374668
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  • 140
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    Exercise-induced necrotic muscle damage and enzyme release in the four days following prolonged submaximal running in rats (1994)
    Springer
    Pflügers Archiv 428 (1994), S. 346-351 
    Details
    ISSN: 1432-2013
    Keywords: Skeletal muscle ; Muscle damage ; Treadmill running ; Serum ; Enzymes ; Water content ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Male Wistar rats were made to run uphill on a treadmill 5.5° incline at 17 m min−1 for 4 h, and killed for muscle and serum sampling 2, 4, 12, 24, 48 or 96 h after the exertion. To estimate the degree of muscle damage,β-glucuronidase activity, total protein concentration, water content and morphology were examined in the red parts of quadriceps femoris (MQF) and soleus (MS) muscles, the distal white part of the rectus femoris muscle (MRF) and the superficial part of triceps brachii muscle (MTB). Simultaneous serum samples were assayed for creatine kinase (CK) activity and carbonic anhydrase III (CA III) concentration. Fibre swelling and interstitial oedema were detected in MS at 4 h and in MQF at 12 h and typical histopathological changes, including inflammation and fibre necrosis, in both muscles 12–96 h post-exertion.β-Glucuronidase activity, a quantitative marker of muscle damage, was increased in MS at 4 h, in MQF at 24 h and in MRF 48 h after the running. No increase occurred in MTB. Water and protein content increased or decreased respectively, faster in MS (2 h post-exercise) than in MQF (12 h) or MRF (12 h). Water content thus contributed to muscle damage by preceding the increase inβ-glucuronidase activity. Serum CK activity was increased 2, 4, and 48 h after the running. Changes in serum CA III concentration were rather similar to those in CK but were not significant. The increase in serum CK was not in concert with the necrotic events in the muscle but occurred considerably earlier (2 h vs. 12–24 h post-exercise). The second peak in CK, 48 h post-exercise (during the necrotic phase), was smaller than the first one. Our results show that serum CK activity is an inaccurate estimate of exercise-induced muscle damage as regards interpretation of the degree and the time course of pathological events in the muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00724517
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    Adrenalectomy increases local cerebral blood flow in the rat hippocampus (1994)
    Springer
    Pflügers Archiv 426 (1994), S. 183-188 
    Details
    ISSN: 1432-2013
    Keywords: Hippocampus ; Corticosterone ; Adrenalectomy ; Local cerebral blood flow ; Diurnal rhythm ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study examined the effect of glucocorticoid manipulations on local cerebral blood flow in the hippocampus. We measured local cerebral blood flow in the hippocampus at 1-h intervals over a 1-day period in freely moving rats, by means of the H2 clearance method, before and after sham adrenalectomy, adrenalectomy or adrenalectomy with corticosterone replacement. We also measured local cerebral blood flow in the prefrontal cortex before and after adrenalectomy. Four weeks after the adrenalectomy, hippocampal blood flow at each time of day was an average of 47% greater than before the operation, showing diurnal variation as before. After the sham adrenalectomy or adrenalectomy with corticosterone replacement, hippocampal blood flow did not change significantly with respect to either its level or its diurnal variation. Local cerebral blood flow in the prefrontal cortex increased by only 19% after adrenalectomy. The present study demonstrates that adrenalectomy causes a remarkable increase in hippocampal blood flow, probably due to a lack of corticosterone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374770
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    Effects of methionine sulphoximine treatment on renal amino acid and ammonia metabolism in rats (1994)
    Springer
    Pflügers Archiv 427 (1994), S. 524-532 
    Details
    ISSN: 1432-2013
    Keywords: Glutamine synthetase ; Kidney ; Intestine ; Glutamine ; Ammonia ; Amino acids ; Metabolism ; Rat ; In vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Renal glutamine metabolism in relation to ammoniagenesis has been extensively studied during chronic metabolic acidosis, when arterial glutamine levels are reduced. However, little is known about the effects of reduced glutamine delivery on renal glutamine and ammonia metabolism at physiological systemic pH values. Therefore, a model of decreased arterial glutamine concentrations at normal pH values was developed using methionine sulphoximine (MSO). Renal glutamine and ammonia metabolism was measured by determining fluxes and intracellular concentrations after an overnight fast in ether anaesthetized normal rats, MSO-treated rats and their pair-fed controls. Moreover, fluxes and intracellular concentrations of several other amino acids were determined concomitantly. After 2 and 4 days of MSO treatment, arterial glutamine concentrations were reduced to 55%, while arterial ammonia concentrations increased by 70%. Kidney glutamine uptake reduced, but systemic pH was unchanged. Fractional extraction of glutamine remained unchanged, suggesting that also in vivo net uptake of glutamine by the kidney at subnormal levels is related to arterial glutamine concentrations. As a result, at day 2 but not at day 4, the kidney reduced the net release of ammonia into the renal vein and thus reduced net renal ammonia addition to body ammonia pools. Therefore at day 2, the kidney seems to play an important role in adaptation to both hyperammonaemia and hypoglutaminaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374270
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    Analysing ion channels with hidden Markov models (1994)
    Springer
    Pflügers Archiv 426 (1994), S. 328-332 
    Details
    ISSN: 1432-2013
    Keywords: Cortical collecting duct ; K+ channel ; Rat ; Isolated tubule ; Patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ion channel current amplitudes (μ) and open probabilities (P o) have been analysed so far by defining a 50% threshold to distinguish between open and closed states of the channels. With this standard method (SM) it is very difficult or even impossible to analyse channels of different size in one membrane patch correctly. A stochastical model, named the hidden Markov model (HMM), separates between observation noise and the stochastic process of opening and closing of ion channels. The HMM allows the independent analysis of μ, P o, and mean dwell times (τ) of different channels in one membrane patch, without defining threshold levels. Using this method errors in the analysis are not summarized like in the SM because all different analysing procedures (e. g. filtering, setting of threshold, fitting processes) are done in one step. Two different K+ channels in excised basolateral membranes of the cortical collecting duct of rat (CCD) were analysed by the SM and the HMM. The μ value of the intermediate-conductance K+ channel (i-K+) was 3.9±0.1 pA (SM) and 3.8±0.2 pA (HMM) for 11 observations. The P o value of this channel was 10.2±4.2% (SM) and 10.1±4.0% (HMM). The mean τ values were 5.4±0.6 ms for the open state and 9.6±2.2 ms and 145±21 ms for the closed states (SM) and 7.8±1.1 ms, 7.7±0.9 ms and 148±24 ms (HMM), respectively. For seven small-conductance K+ (s-K+) channels, which were found in the same membrane patches as the i-K+, an accurate analysis of P o and τ was not possible with the SM. The μ value was 1.0±0.1 (SM), 0.9±0.1 (HMM) pA. P o was 16.6±4.6%, the open τ value was 11.1±2.8 ms, and the closed τ value was 34.9±8.5 ms. The HMM allows the analysis of single-channel currents, P o, and mean τ values when different or more than one ion channel(s) are colocalized in one membrane patch. Where analysis with the SM was possible results did not significantly differ from those obtained with the HMM. Thus for this kind of analysis the method of setting a 50% threshold appears justified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374789
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    Oxygen consumption of oestradiol-treated rats (1994)
    Springer
    Pflügers Archiv 426 (1994), S. 351-353 
    Details
    ISSN: 1432-2013
    Keywords: Rat ; Brown adipose tissue ; Noradrenaline responsiveness ; Oxygen consumption ; Cold acclimation ; Body temperature ; Oxidative capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rectal temperature and oxygen consumption (üüO2) were monitored in female rats acclimated either to cold or to thermoneutrality and with and without chronic administration of oestradiol. The hormone is known to inactivate brown adipose tissue (BAT) and to reduce its response to noradrenaline (NA). The role of sympathetic control was studied by administering NA or the adrenergic blocker propranolol. Oestradiol treatment did not affect rectal temperature in the states of acclimation to thermoneutrality and to cold, nor did it change the hypothermic response of cold-exposed rats to temporary food deprivation. In the cold-acclimated rats, both controls and oestradiol-treated animals exhibited similar degrees of metabolic reduction after propranolol administration in the cold and similar degrees of metabolic activation by NA at thermoneutrality. Rats acclimated to thermoneutrality showed a larger metabolic response to NA when treated with oestradiol. The results suggest that oestradiol, while inactivating the BAT response to NA, activates the NA responsiveness of other metabolically active tissues in cold-induced thermogenesis. The observation of a greater oxidative capacity in the kidney and the rectus abdominis muscle of oestradiol-treated, cold-acclimated rats would be in line with this proposal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374793
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    Respiratory responses to combined hypoxia and hypothermia in rats after posterior hypothalamic lesions (1994)
    Springer
    Pflügers Archiv 426 (1994), S. 371-377 
    Details
    ISSN: 1432-2013
    Keywords: Body temperature ; Respiration ; Electrolytic lesions ; Urethrane anaesthesia ; Hypothalamus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Urethane-anaesthetised rats were exposed to hypoxia (7% O2 in N2) for 5 min periods while body core temperature (T bc) was maintained within the normal range (37–38° C) using an abdominal heat exchanger. Animals were exposed to hypoxia and after placement of electrolytic lesions in either the anterior (n=6) or posterior hypothalamus (n=6). Neither lesion altered respiration while rats breathed air at either T bc. At normal T bc, rats responded to hypoxia with increased ventilation throughout the exposure period. This response was unchanged by lesions in either location. At reduced T bc rats responded to hypoxia with an initial increase in ventilation followed by depression to below air-breathing levels. This depressive response was unchanged after anterior hypothalamic lesions but eliminated after posterior hypothalamic lesions. It is concluded that neurons either originating in the posterior hypothalamus, or passing through it, play a role in the interaction between cold and hypoxia which leads to inhibition of respiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388299
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    Experimental oxygen-induced retinal detachment in the newborn Wistar rat (1994)
    Springer
    Documenta ophthalmologica 87 (1994), S. 315-329 
    Details
    ISSN: 1573-2622
    Keywords: Experimental retinal detachment ; Glial fibrillary acidic protein ; Müller cells ; Oxygen ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We conducted an extensive histological study of the retinas of newborn rats that had been exposed to hyperoxic conditions. Our aim was to verify whether it is possible, using oxygen alone, to induce retinal detachment, a lesion that is characteristic of the more advanced stages of retinopathy of prematurity (ROP). Eight litters (total number of animals: 64) of newborn, albino Wistar rats were used. Four litters (32 rats) were exposed to 80% oxygen for the first ten days of life. Some of these rats were then removed to room-air environments where they were kept for two, three or four more weeks. The other four litters (32 rats) were maintained for the entire period in room-air. On the 11th, 25th, 32nd and 39th days of life rats from both the exposed and control groups were sacrificed and 5 micron sections of their in toto eyeballs were submitted to histological evaluation and immunohistochemical studies. Folding of the internal retinal layers was observed in some of the animals exposed to hyperoxia, as well as those kept in room air. These folds did not alter the overall thickness of the retina itself and were probably congenital. Retinal folds and microdetachments were seen in many of the retinas from the exposed group of rats. Extensive detachment was observed in one of the rats sacrificed after two weeks of room-air recovery, in two of those recovered for three weeks and in two exposed to four weeks of room air. The sections containing these areas of retinal detachment showed marked increases in glial fibrillary acidic protein (GFAP) in immunocytochemical studies, suggesting that Müller cells might play a role in the pathogenesis of retinal detachment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01203341
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  • 147
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    Post-irradiation bladder dysfunction: muscle strip findings (1994)
    Springer
    Urological research 22 (1994), S. 51-55 
    Details
    ISSN: 1434-0879
    Keywords: Bladder dysfunction ; Muscle strip ; Rat ; X-irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Strips of rat detrusor muscle were studied in an organ bath 6 months after X-irradiation at doses of 15 and 25 Gy; cystometric studies in these animals had shown a persistent and significant reduction in compliance. The organ bath study demonstrated an increase in the purinergie sensitivity of irradiated detrusor muscle as compared with control. This was significant: p〈0.0145 for the 25 Gy dose group (n=8) and p〈0.0456 for the 15 Gy group (n=8) at an α,β-methylene-ATP concentration of 10-4 M (Mann-Whitney U-Test). There was no difference in sensitivity to cholinergic or noradrenergic stimulation, or to electrical stimulation of the transmural nerves. The finding of purinergic hypersensitivity in irradiated muscle, coupled with ultrastructural evidence of a neural injury, raises the interesting possibility that a denervation super-sensitivity phenomenon may contribute to the pathophysiology of post-irradiation bladder dysfunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431549
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  • 148
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    Pyelonephritis: renal urokinase and sialidase (neuraminidase) activity in rats fed a standard laboratory diet (1994)
    Springer
    Urological research 22 (1994), S. 57-60 
    Details
    ISSN: 1434-0879
    Keywords: Kidney ; Pyelonephritis ; Rat ; Sialidase (neuraminidase) ; Urokinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Renal stone formation can be caused by many different and varied disturbances, some of which are poorly understood. The relationship between urinary infection and renal stone formation has not been completely clarified. It is argued that renal stones form primarily as a consequence of the hydrolysis of urea by the bacterial enzyme urease. However, no explanation is given for microorganisms that produce urease only occasionally or not at all. The question arises as to wheter the infection-induced microorganisms might not be playing a double role in renal stone formation by not only producting urease, but also by affecting in vivo urokinase (UK) and sialidase (SA) activity. With this in mind, the effect of Escherichia coli on renal UK and SA activity has been studied in male rats with a normal diet. The renal UK (P=0.208) and SA (P=0.2135) activities did not differ significantly between the two kidneys of the same rat. In contrast, when drainage from one kidney of a rat was externally obstructed, the UK and SA activities differed significantly between kidneys (P〈0.015). An increase in UK (r=0.6456, P〈0.0001) and SA (r=0.7507, P〈0.0001) activity was observed over time in the obstructed kidney. Subcutaneous injections with E. coli reduced the UK activity of the obstructed kidney significantly (p=0.0171). However, the SA activity remained the same (P=0.3929). This decrease in the UK activity in the presence of microorganisms may result in an increase in the uromucoid concentration, leading to renal stone formation in the presence of increased salt precipitation on the uromucoid as caused by the urease producing microorganisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431551
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  • 149
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    The effect of active immunization against gonadotropin-releasing hormone on the ultrastructure of the rat ventral prostate (1994)
    Springer
    Urological research 22 (1994), S. 107-113 
    Details
    ISSN: 1434-0879
    Keywords: GnRH-DT vaccine ; Testosterone ; Ultrastructure ; Rat ; Prostate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the effects of active immunization against gonadotropin-releasing hormone (GnRH) on the ultrastructure of the rat ventral prostate, male Sprague-Dawley rats received three consecutive intramuscular injections of 10 μg/100g body weight (D-Lys6)-GnRH-diphtheria toxoid conjugate (GnRH-DT vaccine). Following immunization, test animals developed sufficiently high antibody titres to block the pituitary gonadal axis. Consequently testosterone values dropped to the levels in castrates. This therapy leads to atrophy of the prostate. Following immunization a strong immunological response, indicating the presence of considerable amounts of a GnRH-like peptide, was observed in the ventral prostates as early as 14 days after the first injection of GnRH-DT. Immunoneutralisation of GnRH-like activity may contribute to the effects observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311001
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  • 150
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    Elevated concentrations of the β-subunit of S100 protein in renal cell tumors in rats (1994)
    Springer
    Urological research 22 (1994), S. 251-255 
    Details
    ISSN: 1434-0879
    Keywords: S100 protein ; Rat ; Carcinogenesis ; Renal neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Concentrations of α and β-subunits of S100 protein (S100-α and S100-β) in rat kidney neoplasms, including renal cell and mesenchymal tumors, were determined using a highly sensitive enzyme immunoassay, and both types immunohistochemically localized in tissue sections. Concentration of S100-α in each histological type of rat tumor were lower than in normal kidney, whereas levels of S100-β (mean±SE: 29.7±14.2 ng/mg protein, n=15) in renal cell tumors were significantly higher than in normal kidneys (0.55±0.06 ng/mg protein, n=7), or mesenchymal tumors (1.21±0.43 ng/mg protein, n=9). In normal rat kidney tissues S100-α was immunohistochemically positive in epithelial cells of the distal tubules, the thin limbs of loops of Henle, and the collecting ducts. No appreciable immunostaining for S100-β was found in any nephron segment. Both S100-α and S100-β were positive for renal cell tumors, indicating new appearance of the latter during renal carcinogenesis in rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541902
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  • 151
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    Protein synthesis in the hippocampal slice: Transient inhibition by glutamate and lasting inhibition by ischemia (1994)
    Springer
    Metabolic brain disease 9 (1994), S. 235-247 
    Details
    ISSN: 1573-7365
    Keywords: Hippocampus ; Slices ; Protein synthesis ; Ischemia ; Glutamate ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Protein synthesis was measured in hippocampal slices which were exposed to glutamate (1 mM or 10 mM) or which were deprived of glucose and oxygen (‘in vitro ischemia’) for 15 min. Glutamate at 1 mM, a concentration estimated to occur duringin vivo ischemia did not affect protein synthesis. Ten mM glutamate inhibited protein synthesis immediately after exposure (50% of control values) and reduced ATP levels to about 30% of the control. After two hours, slices fully recovered their protein synthesis and energy metabolism. The effect of 10 mM glutamate was not receptor-mediated, as NMDA, AMPA, or metabotropic receptor antagonists failed to block the glutamate effect. Immediately after ischemia, protein synthesis was reduced to 30% of control values, and 2 hours later it was still depressed to one-half of control values. Energy charge, however, recovered completely. Ischemic inhibition of protein synthesis was not reversed by glutamate receptor antagonists. The data indicate that inhibition of protein synthesis in hippocampal slices during ischemia is not glutamate-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01991197
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  • 152
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    Changes in fibre-type composition and myosin heavy-chain IId isoform in rat soleus muscle during recovery period after hindlimb suspension (1994)
    Springer
    European journal of applied physiology 68 (1994), S. 102-106 
    Details
    ISSN: 1439-6327
    Keywords: Hindlimb suspension ; Recovery ; Soleus muscle ; Fibre-type composition ; Myosin heavy-chain IId isoform ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined the changes in myosin heavy-chain (HC) isoforms and fibre-type composition in rat soleus muscle using both myosin adenosine triphosphatase staining and sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE) analyses during the recovery period after 4 weeks of hindlimb suspension. Although there was no change in type IIc fibres after the suspension, an increase in this type of fibres was observed during the 1- to 4-week recovery period. The increase in type Ilc fibres was considered to be due to a shift from type Ila to IIc fibres. The SDS-PAGE analysis revealed the presence of the HC IId isoform, which was not observed in the control muscle, after a 4-week hindlimb suspension. The HC IId isoform gradually decreased over 3 weeks of recovery and disappeared in the 4th week of recovery after the suspension. These results suggest that the hypogravity conditions induced by hindlimb suspension stimulated the synthesis of the HC IId isoform, whereas an increase in mechanical load to the muscle accelerated the degradation of the HC IId isoform and the synthesis of type Ilc fibres during the recovery period after hindlimb suspension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00599249
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  • 153
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    Ultrastructure of the basal surface of the rat corneal epithelium (1994)
    Springer
    Medical molecular morphology 27 (1994), S. 159-164 
    Details
    ISSN: 1860-1499
    Keywords: NaOH digestion method ; Basal epithelial surface ; Calcium deposits ; Rat ; Scanning electron microscopy (SEM)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Basal surfaces of the rat corneal epithelium were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The epithelium was dissociated from the underlying stroma by dissolving the basal lamina with NaOH, and its basal surface was observed by SEM. Depressions, produced by the indentations of the plasma membrane, were present on the basal cell surfaces in rats which were 15 and 18 months old. TEM observations clarified that electron-dense deposits, presumably containing calcium, were located in the depressions. These depressions also accompanied the thickened basal lamina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02348181
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  • 154
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    Dopaminergic innervation of rat locus coeruleus: A light and electron microscopic immunohistochemical study (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 29 (1994), S. 211-218 
    Details
    ISSN: 1059-910X
    Keywords: Dopamine ; Locus coeruleus ; Rat ; Immunohistochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Dopaminergic innervation of the rat locus coeruleus (LC) was immunohistochemically studied by using monoclonal antibody directed against dopamine (DA) at the light- and electron-microscopic levels. A dense plexus of DA-immunoreactive (IR) varicose fibers was found not only in the cell body area of the LC but also in the dendritic area. Three hundred and forty DA-IR terminal boutons were observed. They were distributed in a wide range of diameters of 0.1-1.8 μm but most of them were large (mean value: 0.98 μm). Sixty-nine percent formed an asymmetric synapse. There were many axo-spinous connections. Small dendrites less than 0.3 μm in diameter displaying synaptic specialization were mostly dendritic spines (75%). Most of the target dendrites seemed to be noradrenergic in nature. It is suggested that dopaminergic innervation may play a powerful role in control mechanisms of activity of NA-containing neurons of the LC. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070290306
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  • 155
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    Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 535-542 
    Details
    ISSN: 1059-910X
    Keywords: Rat ; Albumin ; Fibrinogen ; Immunohistochemistry ; Electromagnetic fields ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Biological effects of electromagnetic fields (EMF) on the blood-brain barrier (BBB) can be studied in sensitive and specific models. In a previous investigation of the permeability of the blood-brain barrier after exposure to the various EMF-components of proton magnetic resonance imaging (MRI), we found that the exposure to MRI induced leakage of Evans Blue labeled proteins normally not passing the BBB of rats [Salford et al. (1992), in: Resonance Phenomena in Biology, Oxford University Press, pp. 87-91].In the present investigation we exposed male and female Fischer 344 rats in a transverse electromagnetic transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse-modulated with repetition rates of 8, 16, 50, and 200 s-1. The specific energy absorption rate (SAR) varied between 0.016 and 5 W/kg.The rats were not anesthetized during the 2-hour exposure. All animals were sacrificed by perfusion-fixation of the brains under chloral hydrate anesthesia about 1 hour after the exposure. The brains were perfused with saline for 3-4 minutes, and thereafter fixed in 4% formaldehyde for 5-6 minutes. Central coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 μm. Albumin and fibrinogen were demonstrated immunohistochemically.The results show albumin leakage in 5 of 62 of the controls and in 56 of 184 of the animals exposed to 915 MHz microwaves. Continuous wave resulted in 14 positive findings of 35, which differ significantly from the controls (P = 0.002). With pulsed 915 MHz microwaves with repetition rates of 200, 50, 16, and 8 s-1, 42 of 149 were positive, which is highly significant at the P = 0.001 level. This reveals that both CW and pulsed 915 MHz microwaves have the potential to open up the BBB for albumin passage. However, there is no significant difference between continuous and pulsed 915 MHz microwaves in this respect.The frequency of occurrence of extravasates (26%) was found to be independent of SAR for SAR 〈 2.5 W/kg, but rose significantly for the higher SAR values (to 43%).The question of whether the opening of the blood-brain barrier constitutes a health hazard demands further investigation. © 1994 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070270608
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  • 156
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    Muscle glycogen repletion and pre-exercise glycogen content: effect of carbohydrate loading in rats previously fed a high fat diet (1994)
    Springer
    European journal of applied physiology 68 (1994), S. 483-488 
    Details
    ISSN: 1439-6327
    Keywords: Carbohydrate loading ; Glycogen utilization ; Glycogen repletion ; Glycogen synthase ; Muscle ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have recently reported that rates of muscle glycogen repletion during the early period of recovery were increased by carbohydrate (CHO) loading in rats previously fed a high fat diet. However, the reason for this remained unanswered. The purpose of this study was to examine whether an increase of glycogen utilization due to an elevated pre-exercise glycogen store would enhance rates of glycogen repletion in muscle. Despite an equal degree of glycogen depletion, the rates of glycogen repletion of soleus, red and white gastrocnemius muscles by postexercise administration of glucose (3.0 g · kg−1 body mass) and citrate (0.5 g · kg−1 body mass) were faster in the CHO loaded (3 days) rats than in the nonloaded rats, as a result of elevated pre-exercise glycogen content and consequently the greater glycogen utilization. The higher rate of muscle glycogen repletion may in part be explained by increased postexercise glycogen synthase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00599517
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  • 157
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    The immunolocalization of small nuclear ribonucleoprotein particles in testicular cells during the cycle of the seminiferous epithelium of the adult rat (1994)
    Springer
    Cell & tissue research 278 (1994), S. 363-378 
    Details
    ISSN: 1432-0878
    Keywords: snRNPs ; Testis ; Spermatocytes ; Spermatids ; Immunocytochemistry ; Chromatoid body ; Intermitochondrial nuage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The objective of this study was to determine the cellular and subcellular distribution of small nuclear ribonucleoprotein particles (snRNPs) in the adult rat testis in relation to the different cell types at the various stages of the cycle of the seminiferous epithelium. The distribution of snRNPs in the nucleus and cytoplasm of germ cells was quantitated in an attempt to correlate RNA processing with morphological and functional changes occurring during the development of these cells. Light-microscopic immunoperoxidase staining of rat testes with polyclonal anti-Sm and monoclonal anti-Y12 antibodies localized spliceosome snRNPs in the nuclei and cytoplasm of germ cells up to step 10 spermatids. Nuclear staining was intense in Sertoli cells, spermatogonia, spermatocytes, and in the early steps of round spermatid development. Although comparatively weaker, cytoplasmic staining for snRNPs was strongest in mid and late pachytene spermatocytes and early round spermatids. Quantitative electron-microscopic immunogold labeling of Lowicryl embedded testicular sections confirmed the light-microscopic observations but additionally showed that the snRNP content peaked in the cytoplasm of midpachytene spermatocytes and in the nuclei of late pachytene spermatocytes. The immunogold label tended to aggregate into distinct loci over the nuclear chromatin. The chromatoid body of spermatids and spermatocytes and the finely granular material in the interstices of mitochondrial aggregates of spermatocytes were found to be additional sites of snRNP localization and were intensely labeled. This colocalization suggests that these dense cytoplasmic structures may be functionally related. Anti-U1 snRNP antibodies applied to frozen sections showed the same LM localization pattern as spliceosome snRNPs. Anti-U3 snRNP antibodies applied to frozen sections stained nucleoli of germ cells where pre-rRNA is spliced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414179
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  • 158
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    The immunolocalization of small nuclear ribonucleoprotein particles in testicular cells during the cycle of the seminiferous epithelium of the adult rat (1994)
    Springer
    Cell & tissue research 278 (1994), S. 363-378 
    Details
    ISSN: 1432-0878
    Keywords: Key words: snRNPs ; Testis ; Spermatocytes ; Spermatids ; Immunocytochemistry ; Chromatoid body ; Intermitochondrial nuage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The objective of this study was to determine the cellular and subcellular distribution of small nuclear ribonucleoprotein particles (snRNPs) in the adult rat testis in relation to the different cell types at the various stages of the cycle of the seminiferous epithelium. The distribution of snRNPs in the nucleus and cytoplasm of germ cells was quantitated in an attempt to correlate RNA processing with morphological and functional changes occurring during the development of these cells. Light-microscopic immunoperoxidase staining of rat testes with polyclonal anti-Sm and monoclonal anti-Y12 antibodies localized spliceosome snRNPs in the nuclei and cytoplasm of germ cells up to step 10 spermatids. Nuclear staining was intense in Sertoli cells, spermatogonia, spermatocytes, and in the early steps of round spermatid development. Although comparatively weaker, cytoplasmic staining for snRNPs was strongest in mid and late pachytene spermatocytes and early round spermatids. Quantitative electron-microscopic immunogold labeling of Lowicryl embedded testicular sections confirmed the light-microscopic observations but additionally showed that the snRNP content peaked in the cytoplasm of mid-pachytene spermatocytes and in the nuclei of late pachytene spermatocytes. The immunogold label tended to aggregate into distinct loci over the nuclear chromatin. The chromatoid body of spermatids and spermatocytes and the finely granular material in the interstices of mitochondrial aggregates of spermatocytes were found to be additional sites of snRNP localization and were intensely labeled. This colocalization suggests that these dense cytoplasmic structures may be functionally related. Anti-U1 snRNP antibodies applied to frozen sections showed the same LM localization pattern as spliceosome snRNPs. Anti-U3 snRNP antibodies applied to frozen sections stained nucleoli of germ cells where pre-rRNA is spliced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414179
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  • 159
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    The role of extracellular calcium in pregnancy-induced attenuation of phenylephrine contraction in rat aorta with functional endothelium (1994)
    Springer
    Journal of comparative physiology 164 (1994), S. 81-87 
    Details
    ISSN: 1432-136X
    Keywords: Vascular smooth muscle ; Phenylephrine-induced contraction ; Pregnancy ; Aorta ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effect of pregnancy on the supply of calcium ions for the contractile responses of rat aortic rings to phenylephrine was investigated. The contractility of intact aortic rings from pregnant rats, compared with that of similar rings from non-pregnant rats, to phenylephrine and potassium chloride was significantly decreased. Contractions of rings from non-pregnant rats, pretreated with phenylephrine or potassium chloride, in response to calcium chloride were greater than those of similarly treated rings from pregnant rats. When the concentration of calcium chloride in the medium bathing the rings was reduced to 0.8 mmol·l-1, the contractile response to phenylephrine was significantly (P〈0.005) inhibited in rings from both pregnant and non-pregnant rats but to a greater extent in rings from non-pregnant rats. Contractions of aortic rings from pregnant rats in response to phenylephrine in calcium-free medium were similar to those of rings from non-pregnant rats, suggesting equal dependence on calcium from intracellular stores. The results suggest that pregnancy decreased the response to calcium influx into the aortic smooth muscle cells through both receptor-and voltage-operated calcium entry pathways. Since de-endothelialisation reversed the pregnancy-induced diminished contraction to phenylephrine, it is likely that pregnancy interferred with contractions induced by activation of receptors with phenylephrine through enhanced production of endothelium-derived relaxing factor(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714575
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  • 160
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    Prothrombin times and activated partial thromboplastin times in toxicology: a comparison of different blood withdrawal sites for wistar rats (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 173-176 
    Details
    ISSN: 1433-2981
    Keywords: APTT ; Blood withdrawal ; PT ; Rat ; Sysmex CA-5000
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The prothrombin time (PT) and the activated partial thromboplastin time (APTT) for untreated male Wistar rats were determined on the Sysmex CA-5000 Instrument for blood taken from the orbital sinus, tail vein, vena cava and aorta. Boxplot and statistical analysis was performed. Only orbital sinus puncture yields unpredictable and unacceptable variation/prolongation of clotting times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798360
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  • 161
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    Comparative NMR studies of diffusional water permeability of erythrocytes from some animals introduced to Australia: Rat rabbit and sheep (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 232-235 
    Details
    ISSN: 1433-2981
    Keywords: NMR ; Rabbit ; Rat ; Red blood cells ; Sheep ; Water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The diffusional water permeability (P d) of the red blood cell (RBC) membrane of rat, rabbit and sheep, representing some animal species introduced to Australia, has been monitored, by a Mn2+-doping 1H nuclear magnetic resonance (NR) technique using a high-field spectometer operating at 400 MHz. In order to make comparisons with previous measurements on the same species (performed at 25 MHz) an analysis of the influence of instrumental parameters and of the state of blood oxygenation was performed on samples of rat and rabbit blood. It was found that by using a short interpulse delay (around 100 µs) in the Carr-Purcell-Meiboom-Gill sequence, and by performing the measurements of the transverse relaxation time of the water in the cell interior (T 2i) on packed cells (haematocrit 〉95%), the values of the water exchange time (T e) obtained with a high-field spectrometer are comparable with those obtained by using a low-field NMR spectrometer. The values of the diffusional water permeability (P d), calculated from the T e values, were, at 24.6°C around 10 × 10−3 cm/s in case of rat and rabbit RBC and around 5 × 10−3 cm/s for sheep RBC; at 37°C the P d values were around 16 × 10−3 cm/s for rat RBC, 14 × 10−3 cm/s for rabbit RBC and 7 × 10−3 cm/s for sheep RBC. These values are very close to the P d values previously reported for the European counterparts of these species. There were no significant differences in the P d values between laboratory rabbits and wild rabbits, or between castrated males, pregnant or nonpregnant females. These results suggest that no changes in the RBC water permeability are correlated with marked alterations in the habitat of animal species introduced to Australia or by sex hormone status. If the NMR instrument-parameters are carefully chosen then comparative studies of RBC water permeability in different laboratories, at separate locations and using different instruments are meaningful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185179
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  • 162
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    The immune response in lymphoid organs of rat: A cytochemical study (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 37-42 
    Details
    ISSN: 1433-2981
    Keywords: Escherichia coli ; Immunisation ; Lymphoid organs ; Rat ; Tissue Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Variations in the activity of lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), dihydrofolate reductase (DHFR) and alkaline phosphatase (ALP) were studied, using the light microscope (LM), and cytochemical reactions in lymphoid organs (lymph node, spleen, thymus) of rats, up to day 5 following Escherichia coli immunisation. Increased levels of LDH and DHFR in the T-area of lymph nodes and of spleen were seen from day 2 to day 4 postimmunisation. The SDH reaction in lymph nodes and in the spleen increased during days 2 and 3 but decreased on day 4 postimmunisation. Considerable increases in the activities of LDH and SDH were seen in thymus at all times postimmunisation. The DHFR reaction product also increased but less markedly. No reaction for ALP was observed in lymphocytes of lymphoid organs studied. Following E. coli immunisation, there is an increase in glycolytic and respiratory metabolism, and in the synthesis of proteins in T-dependent areas of lymphoid organs. These increases are correlated with immune activation of T-cells in these organs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368265
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  • 163
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    Effects of fasting on haematology and clinical chemistry values in the rat and dog (1994)
    Springer
    Comparative clinical pathology 4 (1994), S. 152-156 
    Details
    ISSN: 1433-2981
    Keywords: Clinical chemistry ; Dog ; Fasting ; Haematology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Many regulatory toxicity guidelines and the recommendation of AACC-DACC/ASVCP joint task force of the USA on clinical pathology testing require overnight fasting for rats and non-rodents before blood sampling. However, the reason why animals must be fasted before blood sampling is unclear in toxicology studies. Fasting, one of many preanalytical conditions, can lead to false low or high values, which in turn may lead to misinterpretation of test compound effects in toxicological studies. This paper reviews the literature with respect to fasting, and reports on our own studies, in the hope of increasing the awareness among investigators of these problems. Haematocrit values and plasma chemistry values in blood obtained from rats and dogs following fasting were compared with unfasted animals. In male F344 rats, after 16 h fasting, body weight decreased. Increases in aspartate aminotransferase (AST)/glutamic oxaloacetic transaminase (GOT) and decreases of plasma alkaline phosphatase (ALP), total cholesterol (CHO), triglycerides (TG), phospholipids (PL), urea nitrogen (UN) and calcium were observed. Haematocrit, plasma alanine aminotransferase (ALT)/glutamic pyruvic transaminase (GPT), total proteins (TP), glucose, and inorganic phosphorus (IP) were unchanged. In male beagle dogs after 16 h fasting, TG, PL, UN, calcium and IP were decreased. Haematocrit, ALP, TP, albumin, glucose, CHO, creatinine, AST/GOT, ALT/GPT, LDH and CPK were not changed. Our own studies show that in order to avoid excessive stress to test animals, the fasting period should be decided case by case, and not made uniform in toxicology studies. It would be useful if regulatory guidelines made some mention of both the effect of feeding, and of stress caused by fasting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00798356
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  • 164
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    Microvascular transfers of serratus anterior muscles in rats (1994)
    Springer
    European journal of plastic surgery 17 (1994), S. 1-4 
    Details
    ISSN: 1435-0130
    Keywords: Rat ; Free flaps ; Serratus anterior ; Microvascular surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The serratus anterior muscle in the rat is supplied by the serratus division of thoracodorsal vessels, in a pattern similar to man [2]. The serratus anterior muscles were transferred to the groin area as a free muscle flap in 17 rats and as a free muscle graft in 13 rats. In the free muscle flap group, the serratus anterior muscles of 8 of 10 rats survived; histological examination showed them to be viable and the vascular anastomoses were patent at the 30th day. In the free muscle graft group, all of the muscle grafts became necrotic. As a result, it is concluded that the microvascular transfer of serratus anterior muscles in rats is a useful small animal model for microsurgical laboratory training of clinical free flap transfers and also for performing pharmacological and biochemical studies in transplanted muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00176491
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    Selective association of nerve fibres immunoreactive for substance P or bombesin with putative cholinergic neurons of the male rat major pelvic ganglion (1994)
    Springer
    Cell & tissue research 278 (1994), S. 589-594 
    Details
    ISSN: 1432-0878
    Keywords: Autonomic ganglia ; Neuropeptides ; Pelvic plexus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The male rat major pelvic ganglion contains both sympathetic and parasympathetic neurons that supply the lower urinary and digestive tracts, and the reproductive organs. The aim of this study was to describe the distribution and identify potential targets of sensory and intestinofugal axons in this ganglion. Two putative markers of these projections were chosen, substance P for primary sensory axons and bombesin for myenteric intestinofugal projections. Varicose substance P-immunoreactive axons were associated only with non-noradrenergic (putative cholinergic) somata, and most commonly with those that contained vasoactive intestinal peptide. Immunoreactivity for substance P was also present in a small group of non-noradrenergic somata, many of which were immunoreactive for enkephalins, neuropeptide Y or vasoactive intestinal peptide. Bombesin immunoreactivity was found only in preterminal and terminal (varicose) axons, the latter of which were exclusively associated with non-noradrenergic somata that contain neuropeptide Y-immunoreactivity. Some varicose axons containing either substance P-or bombesin-immunoreactivity were intermingled with clumps of small, intensely fluorescent cells. These studies indicate that substance P-and bombesin-immunoreactive axons are likely to connect with numerically small, but discrete, populations of pelvic neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331378
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  • 166
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    Expression of the α-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig (1994)
    Springer
    Cell & tissue research 278 (1994), S. 617-624 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light- and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrophs. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050253
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  • 167
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    Electronic Resource
    Expression of the α-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig (1994)
    Springer
    Cell & tissue research 278 (1994), S. 617-624 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light-and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrops. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331382
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  • 168
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    Zona glomerulosa of the adrenal gland in a transgenic strain of rat: a morphologic and functional study (1994)
    Springer
    Cell & tissue research 278 (1994), S. 21-28 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Adrenal cortex ; Renin-angiotensin system ; Steroidogenesis ; Electron microscopy ; Morphometry ; Rat ; transgenic (mRen2) 27
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Transgenic rats for the murine Ren-2 gene display high blood pressure, low circulating levels of angiotensin II, and high renin content in the adrenal glands. Moreover, transgenic rats possess an increased aldosterone secretion (maximal from 6 to 18 weeks of age), paralleling the development of hypertension. To investigate further the cytophysiology of the adrenal glands of this strain of rats, we performed a combined morphometric and functional study of the zona glomerulosa of 10-week-old female transgenic rats. Morphometry did not reveal notable differences between zona glomerulosa cells of transgenic and age- and sex-matched Sprague-Dawley rats, with the exception of a marked accumulation of lipid droplets, in which cholesterol and cholesterol esters are stored. The volume of the lipid-droplet compartment underwent a significant decrease when transgenic rats were previously injected with angiotensin II or ACTH. Dispersed zona glomerulosa cells of transgenic rats showed a significantly higher basal aldosterone secretion, but their response to angiotensin II and ACTH was similar to that of Sprague-Dawley animals. Angiotensin II-receptor number and affinity were not dissimilar in zona glomerulosa cells of transgenic and Sprague-Dawley rats. These data suggest that the sustained stimulation of the adrenal renin-angiotensin system in transgenic animals causes an increase in the accumulation in zona glomerulosa cells of cholesterol available for steroidogenesis, as indicated by the expanded volume of the lipid-droplet compartment and the elevated basal steroidogenesis. However, the basal hyperfunction of the zona glomerulosa in transgenic animals does not appear to be coupled with an enhanced responsivity to its main secretagogues, at least in terms of aldosterone secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305774
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  • 169
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    Electronic Resource
    Electron correlations and transport effective mass in narrow-band systems and the Hubbard model (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 727-738 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Hubbard model is rederived from a tight-binding band calculation, showing that, as long as parameters are properly chosen, the model is justified for calculating electronic properties of narrow-band systems. The treatment is extended by including correlations and it was found that bound solutions called dimers exist. The concept of dimers is found to be very powerful for understanding the unusual properties of heavy fermion systems. However, a Mott-Hubbard-like model may be required to calculate properties of high Tc cuprates. © 1994 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490514
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  • 170
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    Addendum (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 771-771 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490516
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  • 171
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490601
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  • 172
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    Ab initio study of the low-lying electronic states of the CH2NO2 radical (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 781-788 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio electronic structures calculations are reported for the four low-lying electronic states X 2B1, 2B2, 2A2, and 2A1 of the CH2NO2 radical. The geometric parameters for the ground-state X 2B1 are predicted by MRSDCI calculations with a double zeta plus polarization basis set. The vertical excitations energies for these electronic states are determined using MRSDCI/DZ+P calculations at the ground-state equilibrium geometry and in agreement with the recent experimental data obtained via PES of the CH2NO2- anion. The oscillator strenghts and the radiative lifetimes for these electronic states and the spin properties for the ground state are calculated based on the MRSDCI wave functions, predicting results in good agreement with available experimental data. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490603
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  • 173
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    Electronic Resource
    Feynman path integral representation for many-fermion interacting systems (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 789-804 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A many-fermion interacting system is investigated within the scenario of the Feynman path integral representation of quantum mechanics. Short-time propagator algorithms and a basis set, closely related to the coherent states, are used to obtain the many-body analytic propagator. A second-quantized Hamiltonian involving a restricted set of two-body interactions and the whole set of Coulomb interactions are separately and shown to lead to an exact and an approximate propagator, respectively. In the latter case, use of a grand canonical ensemble allows the grand partition function and the density operator matrix to be readily obtained. No further approximations are required in the calculation of the trace of the evolution operator involved in the evaluation of statistical expectation values. © 1994 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490604
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  • 174
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    A “canonical functions” approach to the eigenvalues of a system of two coupled Schrödinger equation (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 773-780 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of the determination of eigenvalues for two coupled Schrödinger equations is considered. A new method to solve this problem is presented. This method replaces the use of the wave functions (with unknown initial values) by eight canonical functions αij and βij (i = 1,2; j = 1,2) having well-defined initial values at an arbitrary “origin” r0. These functions are collected in four couples; each one is the solution of the given coupled equations. For a given E, an “eigenvalue functions” D(E) is defined by an analytical expression depending on αij (r) and βij (r) at r = 0 and r = ∞ only. The successive eigenvalues En of the given system are precisely the successive intersection of the graph D(E) with the E-axis. The present method eliminates the conventional use of wave function initial values as well as the conventional problem of the prior guess of the limit points; it determines these points automatically. It eliminates also the use of trial values for E and the need of iterations for its correction. The numerical application of a standard example used by Friedman and co-workers (1990) shows that the eigenvlues computed by the present method are highly accurate for low and high levels; the average relative discrepancy between computed and exact levels is about 3.4 × 10 -15 (this discrepancy never exceeds 1.6 × 10 -14), which is almost the precision of the computer. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490602
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  • 175
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    Equilibrium geometry and electronic structure of benzylidene, arylethylidene, and heterocyclic arylidene malononitriles (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 805-816 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium geometry of some benzylidene, arylethylidene, and heterocyclic arylidene malononitriles has been calculated within the framework of the MNDO-MO formalism. Various structural factors are analyzed and discussed in terms of localized and delocalized MOS and π-interaction between methylene malononitrile (MMN) and aryl moieties. The possibility of charge transfer (CT) from aryl to MMN moieties has been examined. The presence of a heterocyclic ring introduces a small perturbation into the MMN nuclear frame. p-Substituents have a pronounced effect on the magnitude and direction of the dipole moment. The variation of ionization potentials and bond order with the Hammet σ p are examined and a straight-line relationship is obtained. The correlation between physiological activity and quantum mechanical properties is analyzed in terms of heat of formation, ionization potential, dipole moment, and charge density on the aryl ring. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490605
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  • 176
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    Brueckner coupled cluster response functions (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 835-848 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A derivation of the linear response function for the Brueckner coupled cluster method is presented that enables the calculation of second-order molecular properties such as frequency-dependent polarizabilities. By using the Brueckner orbital variant of coupled cluster theory, the spurious pole structure inherent in the standard coupled cluster approach with orbital relaxation is avoided. © 1994 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490607
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  • 177
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    Optimized triple-zeta Gaussian basis sets for use with relativistic effective potentials (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 817-833 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contracted split valence 311 Gaussian basis sets optimized for the averaged relativistic effective potentials (AREP) of Christiansen et al. are developed for the main-group elements B—Ne, Al—Ar, and Ga—Kr. These triple-zeta basis sets are intended for use in valence-only molecular calculations with inclusion of correlation. The performance of the optimized basis functions is first analyzed in HF atomic calculations and compared with HF-limit results. Molecular calculations at the HF, MP2, and CISD levels of theory are performed for some selected diatomics, using these potentials and the optimized sets supplemented by one standard d-type polarization function. Results are reported for bond lenghts, harmonic vibrational frequencies, dipole moments, atomization energies, and ionization energies and compared with all-electron reference calculations and experimental data. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490606
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  • 178
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    Long-range Casimir forces - theory and recent experiments on atomic systems. Series edited by F. S. Levin and D. A. Micha, Vol. 1, Finite Systems and Multiparticle Dynamics, Plenum Press, New York, London, 1993 (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 877-878 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490609
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  • 179
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    Announcement (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 49 (1994), S. 879-881 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560490610
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  • 180
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500101
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  • 181
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    A new single-center method to compute molecular integrals of quantum chemistry in slater-type orbital basis of functions (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 21-42 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present work is dedicated to the introduction of a new single-center expansion method derived from the Barnett and Coulson approach leading to reliable numerical algorithms. The basic concept lies in the use of the integral representations of the modified Bessel functions Iλ+1/2 and Kλ+1/2, rather than employing their closed analytical expressions that are known to involve large numbers that usually make the numerical calculation worthless. It is applied to two-center overlap and Coulomb integrals as well as to three-center nuclear attraction integrals useful in density functional theory. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500103
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  • 182
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    Molecular cyclicity and centricity of polycyclic graphs. I. Cyclicity based on resistance distances or reciprocal distances (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 1-20 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rules for molecular cyclicity based on the global indices resulting from reciprocal distances (Harary number, H) or from resistance distances (Kirchhoff number, Kf) were tested in comparison with those elaborated earlier by means of the Wiener index, W. The Harary number and the Wiener number were found to match molecular cyclicity in an almost identical manner. The Kirchhoff number also generally follows cyclicity trends described previously. H is slightly less degenerate than is W, but Kf has practically no degeneracy in the graphs investigated here. Being much more discriminating than the Wiener number (i.e., practically nondegenerate), Kf allowed the formulation of new rules for systems formed from linearly condensed ribbons of even-membered rings with different sizes as well as for branched ribbons. The topological cyclicity patterns are thus reformulated in an extended basis, proceeding from three different graph metrics. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500102
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  • 183
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    Population analysis of pair densities: A link between quantum chemical and classical picture of chemical structure (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 43-53 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pairon population analysis based on the geminal expansion of pair densities is introduced and applied. As demonstrated by numerical data calculated for a series of simple molecules by the semiempirical MNDO method, the resulting populations provide a new simple means of visualizing the molecular structure. In addition to the reproduction of classical structural formula including the multiplicity of individual bonds, the resulting populations confirm the transferability of bond energies and also provide a simple interpretation of the concept of quantum chemical valence. © 1994 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500104
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  • 184
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    The orthogonal and the natural representation for symmetric groups (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 55-67 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present article, improved algorithms for evaluating the irreducible representations of the symmetric group associated with an arbitrary partition, such as the orthogonal, the natural, and the seminormal representation, are introduced and the relations among them are discussed. With the new algorithms, a representation matrix for the orthogonal or the seminormal representation is expressed as the product of three matrices, where two of them are the triangular intrinsic matrices depending on the irreducible representation of the symmetric group; the other relating to the permutation can be given explicitly. Furthermore, we give a concise description for the irreducible representations of the symmetric group and reach an interesting conclusion that the conjugation transformation matrix between the orthogonal and the natural representation is the intrinsic matrix of the symmetric group. © 1994 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500105
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  • 185
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    Eclipsed and staggered conformations of (SIH3)2F+: An ab initio study (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 69-90 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio calculations at 6-31G**, 6-31++G**, and MP2/6-31G** levels were performed on disilyl-fluoronium, (SiH3)2F+, with the SiH3 group eclipsed or staggered. Optimized geometries, total energies, dipole moments, atomic charges, electronic density, and vibrational frequencies were computed. The results were compared with calculated structural parameters and vibrational frequencies of H3SiF, H2SiF+, H2SiF-, and H4SiF+ ions. The basis-set effects were studied. Several thermochemistry parameters - ZPE, thermal energy, rotational constants, and entropies - were also calculated. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500106
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  • 186
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    Announcement (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 91-91 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500107
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  • 187
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500201
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  • 188
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    Ab initio studies on the mechanism of the cycloaddition reaction between ketene and alleneThis project was supported by the national natural science fund of china. (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 93-99 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the cycloaddition reaction between ketene and allene to form methylene-cyclobutanones has been studied theoretically by HF/3-21G and MP2/3-21G. These two reactions are believed to be unsynchronous and concerted, taking place through the twisted transition states. Four orbitals are mainly involved in each reaction, which is a “2 × [1 + 1]”-type cycloaddition. The activated barrier for the two reactions are 27.2 and 27.1 kcal/mol, respectively, at the level of MP2/6-31G* based on the MP2/3-21G geometries, i.e., these two reactions are compatible. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500202
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  • 189
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    Analytic properties of connected moments expansions (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 101-107 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The derivation of the connected moments expansion (CMX) is examined as well as the singularities that arise in the series expansion for the ground-state energy. Explicit analytic results are presented that show a canceling of these singularities. Also, an alternate moments expansion (AMX) is derived that closely models the CMX but displays a varied computational range. © 1994 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500203
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  • 190
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    Theoretical prediction of the Infrared and Raman spectra of O-ethyl S-2-diisopropylaminoethylmethylphosphonothiolateThis paper was originally submitted for inclusion in the paper symposium dedicated to Prof. Robert G. Parr. (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 161-172 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have extended our computations of the structure and of the infrared and Raman spectra of methylphosphonates and related compounds to the O-ethyl S-2-diisopropylaminoethylmethylphosphonothiolate molecule (we abbreviate the name to ESD). We have computed the optimized geometry and the vibrational infrared and Raman frequencies of ESD by means of the Guassian 92 Program Package using 6-31G* basis sets. We assign the vibrational frequencies and we correct each frequency by multiplying it with a previously derived 6-31G* correction factor. The result is a computer-generated prediction of the IR and Raman spectra of ESD. The agreement between our theoretical predictions and the experimental IR spectrum of ESD is surprisingly good. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500208
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  • 191
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    Quantum chemistry study on B14, B142-, and B14H142- (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 173-179 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of B14, B142-, and B14H142- in octahedral symmetry has been investigated by ab initio calculations at the STO-3G and 4-31G levels. The relationship of molecular orbitals among them has been analyzed and it can be found that the number of valence bonding orbitals of high borane obeys the Wade rule. The similarities and difference between boron clusters and carbon clusters are also discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500302
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  • 192
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    Aromaticity in metallacyclobutadienes from the perspective of the valence bond theory (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 189-196 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The valence bond method has been implemented for the study of π-electron systems using a semiempirical CNDO-type Hamiltonian. The algorithm used is based on the Clifford algebra realization of the Rumer-Weyl basis presented by Paldus et al. Using this version of the CNDO-VB approach, the effect of the metal hybridization in the electronic delocalization of metallacyclobutadienes is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500304
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  • 193
    Electronic Resource
    Electronic Resource
    Orbital binding effect in molecular orbital theory (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 197-205 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on the virial theorem and the virial function, a description of the orbital binding effect and the definition of orbital bond order are developed within the framework of molecular orbital theory for both diatomic and polyatomic molecules. Orbital binding effect calculations for N2, CH4, C2H4, C2H2, and C4H4 molecules show that the definition is reasonable. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500305
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  • 194
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    Quantum chemical study of catalysts based on oxides of transition metals (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 181-188 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catalysts based on oxides of transition metals were studied by Xα-DV calculations. The chemical composition and electronic structure of surface layers for platinum(IV) oxide catalysts modified under percompound electrosynthesis were determined by X-ray photoelectron spectroscopic, quantum chemical, and electrochemical data. The main regularities in electronic structure change under the transition from solid pure oxide PtO2 to its, in part, N-substituted PtO2-xNx were analyzed. Then, we looked for perspective catalysts, calculating the electronic structure for analogous compounds of Ir(III), Ir(IV), Rh(III), and Pd(II). We found that the changes in electronic structure of rhodium oxide under O - N-substitution allowed us to predict the excellent properties of its compound as a catalyst for percompound electrosynthesis reactions. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500303
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  • 195
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    Electronic Resource
    Masthead (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500401
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  • 196
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    Quasi-Spin and the pseudo-orthogonal group in the hubbard model (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 207-231 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this article, we demonstrate a complementarity between the quasi-spin SU(2) algebra of the Hubbard model and the pseudo-orthogonal group O(m,m), where n = 2m is the number of lattice sites. It is shown that all N-electron states for the one-dimensional Hubbard model, corresponding to given values of spin and quasi-spin, give rise to an irreducible representation of O(m,m). Moreover, the cyclic group Cn symmetry of the Hamiltonian is investigated and the O(m,m) ↓ Cn branching rules are determined with the use of the U(n) q-dimension formula. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500306
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  • 197
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    Band structures of al-doped superconductors YBa2Cu3-xALxO7 + δ (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 233-242 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on the EHMO approach, an approximate treatment of electronic energy-band structures is suggested. By employing this treatment, computations of the band structures for the Al-doped superconductors YBa2Cu3-xAlxO7 + δ were carried out. It is shown by analysis of the band structures and the density of states that the 2D Cu-O planes in the Y—Ba-Cu—O superconducting system play a dominant role in superconductivity, whereas the 1D Cu—O ribbons have indirectly an influence on superconductivity through the connection of the O(4) atoms to two Cu—O planes. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500402
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  • 198
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    On multireference superdirect configuration interaction in third order (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 243-271 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The superdirect configuration interaction (Sup-CI) method has the usual versatility and stability of the CI methods with computational efficiency typical to that of the many-body methods, such as the many-body perturbation theory (MBPT). The Hamilton operator is projected into a space of a few trial vectors, such as Krylov, Nesbet, or Møller-Plesset correction vectors. In this space, Hamiltonian matrix elements may be directly computed in the many-body fashion, as weighted sums of integral products over orbital indices. The variation-perturbation method based on the first-order wave function is equivalent to the Sup-CI method with a single correction vector of the Møller-Plesset type. Different points of view on the superdirect CI method are discussed and a version in which third-order contributions are computed for a relatively small (10-100) space of reference and correction vectors is tested. Selection of the best “effective first-order spaces” and size-extensivity corrections in Sup-CI are briefly discussed. Møoller-Plesset, Epstein-Nesbet, and other correction vectors are included in the model calculations on the symmetric stretch of bonds in water, acetylene, and the NH2 molecule. Errors are almost independent of molecular geometry and the method appears to be superior than the multireference second-order perturbation methods. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500403
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  • 199
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    Antiaromaticity in relation to 1,3,5,7-cyclooctatetraene structures (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 273-277 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An isodesmic energy analysis has been carried out at the MP2/6-31G*//HF/3-21G level for the nonplanar ground state (1) of 1,3,5,7-cyclooctateraene and for two planar forms, one having complete π delocalization (2) and the other having alternating single and double bonds (3). 1 is found to have a considerable degree of stabilization, which is attributed to limited π delocalization. The polyene 3 is the more stable of the two planar forms; it is a transition state in the inversion between two possible nonplanar structures. 2 is found to be a triplet at the Hartree-Fock level and is a critical point on an alternate pathway between the two possible arrangements of alternating single and double bonds in 3. Both 2 and 3 have negative isodesmic energies, indicating the presence of stabilizing factors. Our results for 3 show that an “antiaromatic” system need not necessarily show a net destabilization. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500404
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  • 200
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    Masthead (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500501
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