bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term potentiation in hippocampal CA3 neurons: Tetanized input regulates heterosynaptic efficacy
Authors: Bradler James E. , Barrionuevo German
Published: January 2005

Three excitatory synaptic inputs to hippocampal CA3 neurons—the mossy fibers, Schaffer collateral/commissural fibers, and fimbrial fibers—were determined to be separate and independent in the pharmacologically disinhibited in vitro slice. Long‐term synaptic potentiation (LTP) was induced in one of these three synaptic inputs, and subsequent synaptic efficacy changes in the other two nontetanized inputs were characterized using current and voltage clamp techniques. LTP in the mossy fiber input was accompanied by potentiation of Schaffer and fimbrial responses, whereas the induction of LTP in the Schaffer pathway was associated with the potentiation of fimbria responses and a depression of mossy fiber responses. LTP induced in the fimbrial response was confined to that input alone.
Structural alterations of dendritic spines induced by neural degeneration of their presynaptic afferents
Authors: Benshalom Gadi
Published: January 2005

Morphological parameters were compared for dendritic spines of spiny stellate neurons in layer IV of the barrel region of mouse somatosensory cortex, which synapse with degenerated thalamocortical afferents (TC spines) and with intact, unidentified axon terminals (UI spines). Spiny stellate neurons were labeled for light and electron microscopic identification by Golgi impregnation and gold toning. Dendritic spines were examined in series of thin sections, and TC spines were ultrastructurally detectable because of the degeneration‐induced characteristic appearance of the TC axon terminals. Results show that the means of the width of the spine head and of the length of the spine stalk were significantly higher in TC spines than in UI spines by about 11 and 25%, respectively. The variability of these two morphological parameters was significantly lower for TC spines. The mean of the spine stalk width at the narrowest cross section of the stalk was about 0.12 μm, with no significant difference observed between the two spine groups. No specific relationship was found in either the TC or the UI groups of spines between the length of the spine stalk and the width of the spine stalk at its narrowest profile.

As structural features typifying transneuronal degeneration were not observed along the dendritic spines examined, it is speculated that the morphological differences encountered between the TC and UI spines may result, at least in part, from the degeneration‐induced synaptic inactivity of the TC axospinous synapses, rather than exclusively from any direct effects of the degeneration process.
Concentrations of mRNAs encoding for preprosomatostatin and preprocholecystokinin are increased after kainic acid‐induced seizures
Authors: Olenik C. , Meyer D. K. , Marksteiner J. , Sperk G.
Published: January 2005

Concentrations of preprosomatostatin‐mRNA and preprocholecystokinin‐mRNA were determined by Northern blot analysis in rats 2, 10, and 30 days after strong seizures induced by a single intraperitoneal injection of kainic acid. At all time intervals examined, levels of preprosomatostatin‐mRNA were increased in the frontal cortex; so were levels of preprosomatostatin‐mRNA in the striatum. Transient increases, i.e., 2 days after kainic acid, of preprocholecystokinin‐mRNA were observed in the frontal cortex and the substantia nigra. Preprocholecystokinin‐mRNA was reduced in the hippocampus 2 and 10 days after kainic acid. Both preprosomatostatin‐ and preprocholecystokinin‐mRNA levels showed a tendency to be reduced in the amygdala/pyriform cortex at all three time intervals.

The increases in mRNA levels suggest enhanced rates of synthesis of the respective neuropeptides subsequent to kainic acid‐induced seizures. They may also reflect a prolonged increase in the activity of the respective peptide‐containing neurons. This is of special interest in the frontal cortex, since in this area both neuropeptides are found in interneurons and are widely colocalized with γ‐aminobutyric acid.
Peripheral induction of burst firing in locus coeruleus neurons by nicotine mediated via excitatory amino acids
Authors: Tung C.‐S. , Ugedo L. , Grenhoff J. , Engberg G. , Svensson T. H.
Published: January 2005

The effect of systemic nicotine administration (50 μg kg−1 i.v.) on the activity of brain noradrenaline neurons in the locus coeruleus (LC) of chloral hydrateanesthetized rats was analyzed with single cell recording techniques and quantitative computer assessment of firing rate, degree of bursting, and regularity of firing. Nicotine caused an increased firing rate of the cells, with an average time of onset of 1.7 s. An increase in burst activity was observed, as well as deregularization of the firing pattern. Intraventricularly administered kynurenic acid (1 μmol), an antagonist of excitatory amino acids (EAA), did not change the firing rate of the LC cells, but did induce a marked regularization of their firing pattern into a pacemaker‐like activity and completely abolish burst firing. The EAA antagonist also blocked all of the above effects of nicotine on the LC neurons as well as their typical burst‐activation response to a peripheral, noxious stimulus such as paw‐pinch. Since the circulation time in the rat is about 20 s, these results provide unequivocal evidence for a peripheral site of origin for the rapid LC activation induced by systemic nicotine administration. The data also allow the conclusion that the nicotine‐induced LC activation is indirect and dependent on EAA in brain. Our results provide evidence for a tonically active EAA input to the LC, being of importance for induction of changes in the spontaneous, pacemaker activity of LC neurons into burst firing or more irregular firing patterns. It is suggested that the LC activation by nicotine may be significant in relation to tobacco dependence.
Dopamine control of seizure propagation: Intranigral dopamine D1 agonist SKF‐38393 enhances susceptibility of seizures
Authors: Turski Waldemar A. , Cavalheiro Esper A. , Ikonomidou Chrysanthy , Bortolotto Zuner A. , Klockgether Thomas , Turski Lechoslaw
Published: January 2005

The involvement of dopamine (DA) in human and experimental epilepsy has been discounted as DAergic drugs have little effect on convulsions. This work presents evidence that bilateral microinjection of the DA D1 agonist SKF‐38393 into the substantia nigra enhances the susceptibility of rats to seizures, with and ED50 fo 20 pmol (range 13‐31 pmol), converting subconvulsant doses of the cholinergic agonist pilocarpine (200 mg/kg; i.p.) into convulsant ones. The proconvulsant action of SKF‐38393 was reversed by blocking D1‐mediated transmission in the substantia nigra with the D1 antagonist SCH‐23390. The D2 agonist LY‐171555 did not modulate the threshold for limbic seizures when injected into the substantia nigra. In the striatum, the D2 agonist LY‐171555 protected rats against limbic seizures induced by systemic administration of pilocarpine (380 mg/kg; i.p.), with an ED50 of 2 pmol (range 1.4–2.8 pmol). The anticonvulsant action of LY‐171555 in the striatum was reversed by haloperidol. The D1 agonist SKF‐38393 did not affect pilocarpine seizures following administration into the striatum. Systemic administration of DAergic drugs showed that the D1 agonist SKF‐38393 decreased the threshold for pilocarpine seizures, with an ED50 of 0.81 mg/kg (range 0.45–1.47 mg/kg), whereas the D2 agonist LY‐171555 had no effect on susceptibility of rats to pilocarpine. Thr proconvulsant action of SKF‐38393 was blocked by the D1 antagonist SCH‐23390. These results suggest that DA differentially modulates seizure threshold in the forbrain acting via D1 mechanisms in the substantia nigra and D2 mechanisms in the striatum.
Direct effect of 17β‐estradiol on striatum: Sex differences in dopamine release
Authors: Becker Jill B.
Published: January 2005

The nigrostriatal dopamine (DA) system is sexually dimorphic. In female but not male rats, striatal DA activity is modulated by gonadal steroid hormones. Ovariectomy (OVX) decreases striatal DA release and turnover. Estrogen replacement restores the response to that of the intact female in estrus. In contrast, castration (CAST) of male rats has no effect on the stimulated release of DA from striatal tissue. This report addresses the question: Dose estrogen act directly on the striatum to induce changes in DA release? Physiological concentrations of 17b̃‐estradiol and other steroids or a nonsteroidal estrogen analog were applied directly to striatal tissue maintained in an in vitro superfusion system. The effect of hormonal treatments on the responsiveness of striatal DA terminals to stimulation was examined in tissue from OVX females and intact and CAST male rats. The results are summarized as follows: (1) Infusion of 17b̃‐estradiol (p < 0.01) and diethylstilbesterol (p < 0.05) increased amphetamine (AMPH)‐stimulated striatal DA release from striatal tissue of OVX female rats compared with the effect of cholesterol. 17alpha‐Estradiol also tended to potentiate the striatal DA response to AMPH, but this result was not statistically significant (p < 0.062). 17b̃‐Estradiol had no effect on AMPH‐stimulated DA release from striatal tissue of intact male rats. (2) The KCl‐stimulated release of DA from striatal tissue of OVX rats exposed in vitro to 100 pg/ml 17b̃‐estradiol (a physiological dose) was significantly greater (p < 0.05) than the response after exposure to vehicle. In contrast, 1,000 pg/ml 17b̃‐estradiol produced a decrease in KCl‐induced striatal DA release (p < 0.05), whereas 17alpha‐estradiol (100 pg/ml or 1,000 pg/ml) did not significantly influences the response to KCl. (3) The pulsatile administration of 17b̃‐estradiol stimulated DA release from strital tissue of OVX females (p < 0.05; compared with tissue from an OVX group that received vehicle or CAST male rats exposed to either 17b̃‐estradiol or vehicle). It is concluded that with tissue from OVX rats, physiological concentrations of estrogen can act directly on striatal tissue in vitro to stimulate DA release and to increase striatal DA responsiveness to stimulation, whereas prolonged exposure or high concentrations of 17b̃‐estradiol decreases striatal DA responsiveness. The striatum and/or the striatal DA system are sexually dimorphic in this regard.
Postsynaptic structure may account for variations in miniature endplate current shapes along frog neuromuscular junctions
Authors: Fortier L. P. , Tremblay J. P.
Published: January 2005

Intracellular recordings were made in the presence of 6–9 m̈M neostigmine with an electrode placed halfway between the distal end and the proximal region of a long simple branch of a frog neuromuscular junction. During the intracellular recording period, an extracellular electrode was placed alternatively at a distal and at a proximal site. The temporal correspondence between the extracellular miniature endplate current and intracellular miniature endplate potential permitted us to identify two miniature endplate potential (MEPP) populations originating, respectively, from the distal and proximal regions. The frequency and intracellular amplitude of MEPPs were higher in the proximal than in the distal region. The rise time and the decay time of the extracellularly recorded MEPC were longer in the proximal region. A significant correlation was observed between the amplitude (in mV) and surface (in mV · ms) of MEPCs. The slope of this regression line was steeper for the proximal region. Furthermore, the correlation coefficient was lower for that region owing to variations of MEPC shape. Our observations suggest that in the presence of anticholinesterase, ACh rebinds more often to acetylcholine receptors in the proximal region because of the presence of longer postjunctional folds.
Effects of haloperidol and clozapine on preprotachykinin‐A messenger RNA, tachykinin tissue levels, release and neurokinin‐1 receptors in the striato‐nigral system
Authors: Christian Humpel , Andrea Knaus Gabriele , Bernhard Auer , Hans‐Gunther Knaus , Christian Haring , Elvar Theodorsson , Alois Saria
Published: January 2005

The effects of haloperidol and clozapine on tachykinin tissue lelvels, preprotachykinin‐A messenger RNA, spontaneous and potassium‐evoked tachykinin release, dopamine D2 receptors, and [125]Bolton‐Hunter‐substance P binding sites in the striato‐nigral system were examined. Chronic administration (10 days) of the dopamine receptor antagonist haloperidol (2 mg/kg, i.p.) significantly decreased tissue levels of substance P like‐immunoreactivity and neurokinin A like‐immunoreactivity in the striatum and the substantia nigra. The corresponding preprotachykinin‐A mRNA was decreased ub tge struatyun, Haloperidol did not affect the potassium‐evoked tachyikinin release in the substantia nigra but significantly increased the spontaneous release. Haloperidol increased the number of D2‐receptors but left [125]Bolton‐Hunter‐substance P binding sites, representing neurokinin 1 (NK‐1) receptors, as determined by competition experiments with selective ligands, unchanged. Clozapine (30 mg/kg, i.m.) did not influence nigral and striatal tachykinin tissue levels, preprotachykinin‐A mRNA and potassium‐evoked release or spontaneous efflux in the substantia nigra, or D2‐receptors and [125I]Bolton‐Hunter‐substance P bindin sites. The present data indicate that neuroleptics influence the striato‐nigral tachykinin system in different ways. Tachykinins may therefore, contribute to the therapeutic and/or untoward effects of certain neuroleptic drugs.
Evalutation of the pharmacological similarities between phenlpopanolamine andamphetamine: Effects on schedule‐controlled behavior
Authors: Wagner George C. , Jarvis Michael F.
Published: January 2005

In an effort to determine the degree to which the repeated administration of phenylp0ropanolamine (PPA) results in the development o tolerance to its disruptive effects on operant responding as wellas cross‐tolerance to the effets of autely administered amphetamine, water‐deprived rats were first trained on a fixed‐ratio 5 (FR‐5) schedule for water presentation. Dose‐response curves for the effects of PPA and amphetamine (administered IP, 15 min presession) were then determined (ED5 = 35.0 and 2.6 mg/kg, respectively) followed by the chronic administration of 40.0 mg/kg PPA (administered IP, 15 min prior to each session). When responding returned to pre hronic rates, the dose‐response curves wee redetermined for both PPA (ED50=220 mg/kg) and amphetamine (ED50=48mg/kg). In a second set of rats, trained under similar conditions, it was observed that pretreatment with alpha‐methyltyrosine (AMT, 100 mg/kg IP, 2 h presession) antagonized the disruptive effets of both PPA and amphetamine, whereas pretreatment with reserpine (0.31 mg/kg, IP, 12 h presession) antagonized the disruptive effects of PPA, but exacerbated the disruptive effects to amphetamine. In a separate experiment, the repeated administration of PPA 1 mg/kg IP resulted in no long‐lasting depetions of atstriatal dopamine, serotonin, or 3,4‐dinhydroxphenylacetic acid (DOPAC) concentrations. These observations indicate that PPA and amphetamine share a similar mechanism of action to the degree that cross‐tolerance develops, but which isnonetheless dissociable with respect to their differential sensitivity to antagonists and their neurotoxic efficacy.
Thyrotropin‐Releasing hormone has profound presynaptic action on cultured spinal cord neurons
Authors: Behbehani Michael M. , Pun R. Y. K. , Means Eugene D. , Anderson Douglas K.
Published: January 2005

Thyrotropin‐releasing hormone (TRH) receptors are widely distributed throughout the nervous systems. In particular, both the dorsal and the ventral horn (VH) neurons contain a rich distribution of TRH receptors, and TRH application to these sites has profound physiological effects. Currently the mechanism of action of TRH is not known. We examined the effect of TRH on ventral horn neurons using intracellular and patch‐clamp techniques. Our results indicate that TRH application profoundly increases the firing rate of VH cells by decreasing membrane conductance. More importantly, TRH causes a significant increase in frequency and amplitude of postsnaptic potentials. Under voltage‐clamp condition, TRH reduces holding current and causes a significant increase in the rate of occurrence and the amplitude of excitatory postsynaptic currents (EPSCS), an effect that lasts for more than 5 minutes. This effect of TRH is not observed in of the EPSCS when it is applied to a region of the cell that is sparsely innervated. These results provide strong evidence that presynaptic mechanisms have a significant role in the excitatory effect of TRH on the VH neurons. Because there is evidence that trophic factors are released from presynaptic terminals, by increasing synaptic activity, TRH can have a trophic influence on the spinal cord neurons. In addition, because there are a significant number of TRH containing neurons within the spinal cord, it is likely that TRH has a major role in information processing within the spinal cord.
Positron emission tomography (PET) studies of dopaminergic/cholinergic interaction in the baboon brain
Authors: Dewry Stephen L. , Brodie Jonathan D. , Fowler Joanna S. , MacGregor Robert R. , Schlyer David J. , King Payton T. , Alexoff David L. , Volkow Nora D. , Shiue Chyng‐Y. , Wolf Alfred P. , Bendriem Bernard
Published: January 2005

Interactions between the dopaminergic D2 recceptor system and the muscarinic cholinergic system in the corpus striatum of adult female baboons (Papio anubis) were examined using positron emission tomography (PET) combined with [18F]N‐methylspiroperidol ([18]NMSP) (to probe D2 receptor availability) and [N‐11C‐methyl]benztropine (to probe muscarinic cholinergic receptor availability). Pretreatment with benztropine, a long‐lasting anticholinergic drug, bilaterally reduced the incorporation of radioactivity in the corpus striatum but did not alter that observed in the cerebellum or the rate of metabolism of [18F]NMSP in plasma. Pretreatment with unlabelled NMSP, a potent dopaminergic antagonist, reduced the incorporation of [N‐11C‐methyl]benztropine in all brain regions, with the greatest effect being in the corpus striatum < cortex < thalamus < cerebellum, but did not alter the rate of metabolism of the labelled benztropine in the plasma. These reduction in the incorporation of either [18F]NMSP or [N‐11C‐methyl]benztropine exceeded the normal variation in tracer incorporation in repeated studies in the same animal. This study demonstrates that PET can be used as a tool for investigating interactions between neurochemically different yet functionally linked neurotransmitters systems in vivo and provides insight into the consequences of multiple pharmocologic administration.
Differential effects of intracerebroventiricular colchicine administration on the expression of mrnas for neuropeptides and neurotransmitter enzymes, with specila emphasis on galanin: An in situ Hybridization Study
Authors: Cortės Roser , Ceccatelli Sandra , Schalling Martin , Höukfelt Tomas
Published: January 2005

The axonal transport blocker clochicine has been extensively used in immunohistochemical studies to induce accumulation of neuroactive compounds, especially neuropeptides, in neuronal somata and thus improve their visualization. To assess whether colchicine might, in addition, ifluence the synthesis of such compounds, we have now used in situ hybridization to examine the level of mRNAs encoding for several neuropeptides (galanin[GAL], cholecystokinn [CCK], somatostatin [sOM], neuropeptide Y[NPY]) and neurotransmitter‐synthesizing enzymes (chloine acetyltransferase [ChAT], tyrosine hydroxylase [TH], amino acid decarboxylase [AADC], and glutamic acid decarboxylase [GAD]) after intraventricular administration of the drug. The results show that colchicine differntially modifies the level of several mRNA species in different brain areas. Thus GAL mRNA levels increase in virtually all regions examined, including the basal forebrain, hypothalamus, dorsal raphe nucleus, locus coeruleus to be induced in the ipsilateral hemisphere in region such as the cortex, hippocampus, striatum, lateral septum, and some nuclei of the thalamus as well as within white matter, where it cannot be detected in control animals. Although GAL mRAN in the vast majority of cases is neuronal, some findigs indicate a possible glial localization. In parallel, clochicine depletes chAT mRNA and increase GAD mRNA in the basal forbrain and striatum and decreases AADC mRNA in the dorsal raphe nucleus and locus coeruleus. In the latter nucleus, NPY and TH mRNA level are increased by clochcine. In contrast, TH mRNA and also CCK mRNA level decrease in the substantia nigra. In the cortex, hippocampus, and thalamus ipsilateral to colchicine injection CCK mRNA level are markedly decrease, whereas sOM mRNA level decreas and NPY mRNA increase in the hippocampus, but unchanged in the cortex. The result are discussed with reference to the possible artifacts that the use of colchicine might induce in immunohistochemical mapping studies and in relation to possible neurotoxic action of colchicine, in some cases perhaps related to impaired retrograde transport of growth factor(s).
Effect of thiol group modification on ion flux and ligand binding properties of the GABAA‐benzodiazepine receptor chloride channel complex
Authors: Allan A. M. , Baier L. D.
Published: January 2005

Agents that modify thiol groups have been shown to alter ligand binding at a variety of receptor sites. In addition, alkylation of sulfhydryls has been shown to block ion channel conductance. We studied the effects of thiol reagents on γ‐aminobutyric acid (GABA)‐activated chloride flux (36Cl−) and [3H]‐diazepam binding in mouse brain membrane preparation (microsacs). Incubation of microsacs in the presence of: mercuric chloride (HgC12), p‐chloromercuriphenylsulfonic acid (pCMBS), hydroxymercuribenzoate (HMB), n‐ethylmaleimide (NEM), or iodoacetic acid (IAA) attenuated GABA‐stimulated Cl− uptake. The thiol reagents reduced both maximal stimulation and the potency of GABA to induce Cl− uptake. Thiol reagent treatment decreased the affinity of high‐affinity [3H]‐muscimol equilibrium binding. Supernatant prepared from microsacs treated with pCMBS stimulated Cl− uptake in the absence of GABA agonist in microsacs unexposed to thiol reagents. The supernatant taken from pCMBS‐treated microsacs also stimulated [3H]‐diazepam binding. This effect was blocked by the addition of the GABA receptor antagonist bicuculline. The concentration of endogenous GABA in supernatant from pCMBS‐treated microsacs was sixfold greater than that in supernatant from control microsacs. This increase in levels of endogenous GABA by thiol reagents was due to both an increase in GABA release and a decrease in high‐affinity GABA uptake.
Presynaptic mechanism for heterosynaptic, posttetanic depression in area CA1 of rat hippocampus
Authors: Grover Lawrence M. , Teyler Timothy J.
Published: January 2005

Conditioning stimulation applied to afferent fibers in stratum radiatum or stratum oriens of hippocampal area CA1 produced heterosynaptic, posttetanic depression (PTD) of excitatory postsynaptic potentials (EPSPs). PTD amounted to a 60–80% reduction of EPSPs and recovered over a 5 min period. Conditioning stimulation also induced a posttetanic hyperpolarization (PTH) averaging 4 mV and decaying over a 1–1.5 min period. PTH was accompanied by a large reduction in input resistance. We sought to determine the pre‐ or postsynaptic locus of heterosynaptic PTD. Our results suggest that PTD reflects a presynaptic mechanism: (1) PTD was observed for both N‐methyl‐Daspartate (NMDA) and non‐NMDA receptor mediated EPSPs; (2) Direct depolarization of pyramidal cells, substituted for the synaptic depolarization induced by conditioning stimulation, did not elicit PTD; (3) PTD and PTH were differentially affected by pharmacological and postsynaptic manipulations; (4) Conditioning stimulation depressed responses to pressure applied glutamate, but the magnitude and duration were too small to account for PTD. Since afferent fiber volleys were not depressed following conditioning stimulation, while field EPSPs were, we conclude that conditioning stimulation suppresses synaptic release of glutamate. © 1993 Wiley‐Liss. Inc.
Immunochemical localization of calcium/calmodulin‐dependent protein kinase I
Authors: Picciotto Marina R. , Zoli Michele , Bertuzzi Gloria , Nairn Angus C.
Published: January 2005

Ca2+/calmodulin‐dependent protein kinase I (CaM kinase I) was originally identified in rat brain based on its ability to phosphorylate site 1 of synapsin I. Recently a cDNA for the rat brain enzyme has been cloned and the primary structure elucidated [Picciotto et al. (1993), J. Biol. Chem., 268:26512–26521]. The rat cDNA encoded a protein of 374 amino acids with a calculated Mr of 41,636. Antibodies have now been raised against the recombinant kinase expressed in E. coli as a glutathione‐S‐transferase fusion protein. Immunoblot analysis of rat cortex lysates revealed two major immunoreactive bands of ∼Mr 38,000 and 42,000. Minor immunoreactive species of slightly lower Mr were also detected. Two distinct CaM kinase I activities were partially purified from rat brain and shown to correspond to the two major immunoreactive species. A variety of immunoreactive species of Mr 35–43,000 were detected in “brain” tissue from cow, zebra finch, goldfish, Xenopus, lamprey, and Drosophila. In rat brain, immunocytochemistry revealed strong staining in cortex, hippocampus, amygdala, hypothalamus, brain stem, and choroid plexus. The labelling was mainly observed in neuropil but clusters of intensely labelled neuronal cell bodies were also detected all along the neuraxis. Neuronal nuclei and glial cells did not appear to be stained. Subcellular fractionation studies confirmed the cytosolic localization of the kinase in the brain. In various rat non‐neuronal tissues and in a number of cell lines, immunoreactive species of ∼Mr 38,000 and ∼42,000 were detected at lower levels than that detected in brain. The Mr 38,000 and 42,000 species were also found in different ratios and at different levels in the non‐neuronal tissues. These results support a role for CaM kinase I in the regulation of multiple neuronal processes. Furthermore, the widespread cell and tissue distribution suggests that CaM kinase I may function as a ubiquitous multi‐functional protein kinase. Finally, the multiple immunoreactive species may represent isoforms of CaM kinase I. © 1995 Wiley‐Liss, Inc.
Effect of calpain on the composition and structure of postsynaptic densities
Authors: Dosemeci A. , Reese T. S.
Published: January 2005

Endogenous calcium‐activated proteases, the calpains, are thought to play a role in the regulation of postsynaptic function. Here we characterize some biochemical and morphological effects of calpain on isolated postsynaptic densities (PSDs). When a PSD preparation from rat forebrain was treated with exogenous calpain, many proteins, including spectrin, tubulin and the α‐subunit of calcium calmodulin‐dependent protein kinase (α‐CaM kinase), were proteolyzed at varying rates, while another major protein, actin, remained intact. The selectivity of calpain action became more apparent in experiments designed to achieve limited proteolysis by using a lower calpain‐to‐protein ratio; it was possible to obtain extensive breakdown of spectrin with no decrease in the levels of either tubulin, α‐CaM kinase, or actin. Electron microscopy of freeze‐substituted preparations showed that limited calpain action caused a partial unraveling of the PSD, in which the characteristic central dense lamina became wider and less dense. We interpret these changes as due to calpain‐mediated breakdown of cross‐bridging elements, leading to a partial unraveling of the central PSD lamina. Opening up of the PSD structure following limited calpain action could facilitate exposure of previously occluded functional sites within the PSD and contribute to the modification of the synaptic function. © 1995 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America

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Antibodies to calcium channels from ALS patients passively transferred to mice selectively increase intracellular calcium and induce ultrastructural changes in motoneurons
Authors: Engelhardt József I. , Siklós László , Kőműves Lászloó , Smith R. Glenn , Appel Stanley H.
Published: January 2005

Antibodies to Ca channels in ALS patients IgG can be demonstrated to enhance Ca current and cause cell injury and death in a motoneuron cell line in vitro. To determine whether these antibodies can alter neuronal calcium homeostasis in vivo IgG fractions from six ALS patients were injected intraperitoneally into mice, and neurons assayed by ultrastructural techniques for calcium content. After 24 h, all six ALS IgG (40 mg/animal) increased vesicle number in spinal motoneuron axon terminals, and in boutons synapsing on spinal motoneurons. Using the oxalate‐pyroantimonate technique for calcium precipitation, these antibodies produced dose‐dependent calcium increases either in axon terminal synaptic vesicles and mitochondria, or in rough endoplasmic reticulum, mitochondria, and Golgi complex of spinal motoneuron and frontal cortex pyramidal cells. ALS IgG was itself internalized and also induced neurofilament H phosphorylation. The observed changes in ultrastructure and calcium compartmentation were restricted to motoneurons; normal and disease control IgG, which did not possess antibodies enhancing calcium entry, did not exert similar effects. These data demonstrate that ALS IgG containing Ca‐channel antibodies can alter calcium homeostasis of motoneurons in vivo. © 1995 Wiley‐Liss, Inc.
Über neue Methoden in der Alkali‐ und Acidimetrie, Oxydimetrie und Fällungsmaßanalyse. Hydrolytische Fällungsmaßanalyse und Mercurimetrie
Authors: Jellinek Karl , Keebs Paul
Published: January 2005

Die Auffindung von 4 neuen anorganischen Indikatoren für die Acidimetrie, und zwar: Indikatoren, die den Umschlag durch Trübung anzeigen. a) Pb‐Salz für alle Säuren und Basen außer H2SO4. b) Cu‐Salz fur alle Säuren und Ammoniak. c) Ag‐Salz für alle Säuren außer HCl, HJ, HBr und alle Basen außer Ammoniak.
Über die Oxydation von Hydroxylamin
Authors: Kurtenacker Albin , Neusser Robert
Published: January 2005

Oxydiert man Hydroxylamin mit überschüssigem Permanganat, so hängt der Permanganatverbrauch sehr von der Azidität bzw. Alkalität der Lösung ab und erreicht in schwach alkalischer Lösung ein sehr scharf ausgeprägtes Minimum.
Über die Karbonate der seltenen Erden. II. Die thermische Dissoziation der Ceritcarbonate
Authors: Preiss Josff , Rainer Norbert
Published: January 2005

Die thermische Dissoziation, die durch Erhitzungs‐ und Temperatur‐Gewichtskurven verfolgt wurde, zeigte, unterstützt durch die Ergebnisse der Hydrolyse, daß den neutralen Ceritcarbonaten die Strukturformel zukommt, deren 3 CO2 verschieden starke Bindung haben, die in allen Fallen eine Stufendissoziation bedingt.
Beiträge zur systematischen Indikatorenkunde. 7. Mitteilung. Die Konstruktion von Titrationskurven
Authors: Thirl A.
Published: January 2005

1. Mit Hilfe des „logarithmischen Verfahrens”︁, bei dem der Zustand einer Mischung von Säuren und Basen als Funktion der Säurestufe der Lösung entwickelt wird, läßt sich eine wesentliche Vereinfachung der Berechnung erzielen.
Beiträge zur Theorie der elektrolytischen Ionen. Nr. 29. Über eine Verbesserte Methode der Leitfähigkeitsmessung durch Einführung des Röhrenverstärkers und ihre Begründung
Authors: Lorenz Richard , Klauer Hans
Published: January 2005

Es wird der Röhrenverstärker in die Methode von KOHLRAUSCH zur Bestimmung des Leitvermögens von Elektrolyten eingeführt, seine Wirkungsweise und sein Einfluß innerhalb dieser Methode werden untersucht.
II. Die Beziehung zwischen der Rührgeschwindigkeit und der Reaktionsgeschwindigkeit in heterogenen Systemen
Authors: Klein A.
Published: January 2005

Die Reaktionsgeschwindigkeit in heterogenen Systemen ist als Summe zweier Größen aufzufassen, deren eine für die gegebene Reaktion konstant und die andere der Rührgeschwindigkeit proportional ist. Der Proportionalitätsfaktor ist von der Rührvorrichtung abhängig und zwar wird er schon durch geringe Änderungen dieser deutlich beeinflußt.
Experimentelle Studie über den Verlauf der Salpetrigsäurebildung aus Salpetersäure und durchströmendem Stickoxyd
Authors: Abel E. , Harasty D.
Published: January 2005

Ausgehend von der Fragestellung, von welchen Faktoren die Geschwindigkeit der Reduktion von Salpetersäure zu salpetriger Säure bei Durchleiten von Stickoxyd abhängt, wurde der Einfluß der Durchströmungsgeschwindigkeit des Gases, der Oberflächenausdehnung und des Reaktionsvolumens untersucht, und an der unter den eingehaltenen Versuchsbedingungen auch in ihrer Kinetik unvermeidlich heterogenen Reaktion festgestellt, daß ihre Geschwindigkeit sowohl mit der Konzentration der H.‐Ionen als mit der der NO3'‐Ionen symbat geht; gegenüber dem Anfangsgehalt an gelöstem Stickoxyd ist die Reaktion infolge der aus dem Gasstrom gewährleisteten Nachlieferung wenig empfindlich; die genannte Symbasie ist bezüglich des H.‐Ions — insbesondere im Bereiche schwacher Salpetersäurelösungen — erheblich ausgeprägter als hinsichtlich des NO3'‐Ions, vielleicht infolge spezifischer Verzögerungswirkungen, wie solche bei Sulfat im weiten Umfange nachgewiesen wurden. Das charakteristischste Merkmal der Reaktion ist ihre Autokatalyse durch ihr Reaktionsprodukt, die salpetrige Säure, deren Bruttoeinfluß sich durch Superposition einer positiv und einer negativ autokatalysierenden Komponente ergibt, an welch letzterem Anteil jedenfalls die Lage des angestrebten Gleichgewichts verantwortlich ist.
Selektive Bestimmung von Vanadium in Gegenwart von Eisen und Chrom. I. Bestimmung von Vanadium in Gegenwart von Eisen
Authors: Someya Kinichi
Published: January 2005

Die Benutzung von Diphenylamin als Indikator bei der Titration von Vanadinsäure mit Ferrosulfat vermeidet den Fehler, den die übliche Methode mit Ferricyanid besitzt, und vergrößert die Genauigkeit der Bestimmung von Vanadium in Gegenwart von Eisen. Vanadinsäure kann auch erfolgreich bestimmt werden durch Zusatz eines Überschusses von Ferrosulfat und Rücktitration des Überschusses mit Kaliumbichromat in der Kälte.
Die Aktivierung von Atomen und Molekeln und der Mechanismus der chemischen Umwandlung
Authors: Dhar N. R.
Published: January 2005

Die folgenden Ergebnisse stützen die Ansicht von der Existenz aktiver Atome und Molekeln in einem System:

Reaktionen zwischen Elektrolyten sind gewöhnlich zurückzuführen auf die Vereinigung von Ionen entgegengesetzter Ladung; sie haben viel größere Geschwindigkeiten als Reaktionen, an denen keine Ionen beteiligt sind. Die Ionen befinden sich im aktiven Zustand und sind daher geneigt, sich miteinander zu vereinigen.

Um die begrenzte Geschwindigkeit einer gewöhnlichen chemischen Reaktion zu erklären, muß angenommen werden, daß nicht alle Molekeln eines reagierenden Systems sich in demselben Zustand der Aktivierung befinden, und daß aktive und inaktive Molekeln in ein und demselben Medium auftreten. Die Zahl der aktiven Molekeln ist im Vergleich mit der Zahl der inaktiven Molekeln sehr gering. Chemische Unwandlungen finden nur statt zwischen aktiven Molekeln.

Bei gewöhnlichen thermischen Reaktionen werden die Molekeln vermutlich aktiviert durch die Absorption von infraroter Strahlung, die wegen der Temperatur stets in einem System vorhanden ist.
Untersuchungen über die Löslichkeit des Magnesiumhydroxyds. I. Von der Existenz verschiedener Modifikationen von Magnesiumhydroxyd
Authors: Gjaldbaek J. K.
Published: January 2005

Das Magnesiumhydroxyd existiert in zwei Modifikationen mit wohldefinierter Löslichkeit, einer leichter löslichen Form, labilem Magnesiumhydroxyd, und einer schwerer löslichen Form, stabilem Magnesiumhydroxyd.
Über die Potentiometrische Einstellung von Titantrichloridlösungen
Authors: Kolthoff I. M. , Tomiček O. , Robinson Conmar
Published: January 2005

Kaliumbichromat ist als Ursubstanz zur Einstellung von Titanchlorid sehr geeignet. Zur Beschleunigung der Potentialeinstellung in der Nähe vom Äquivalenzpunkt ist der Zusatz von ein wenig Kupfersulfat von Vorteil. Bei der Einstellung von Titanchlorid mit Kupfersulfat erhält man einen kleinen Sprung und einen etwas zu niedrigen Titer.
Die Verteilung eines Stoffes zwischen zwei Lösungsmitteln und die Löslichkeit
Authors: Perschke Wlad.
Published: January 2005

1. Es ist auf Grund der thermodynamischen Hauptätze ein theoretischer Beweis gegeben für die Gleichheit des Verteilungskoeffizienten eines Stoffes zwischen zwei nichtmischbaren Flüssigkeiten mit dem Löslichkeitsverhältnis desselben Stoffes in denselben Lösungsmitteln und bei derselben Temperatur.
Bemerkungen über das neue Massenwirkungsgesetz. III. Zur Theoretischen Berechnung der Isotherme
Authors: Lorenz Richard , Mannheimer M.
Published: January 2005

Wir fassen im nachfolgenden die Hauptergebnisse der Bemerkungen I, II, III zusammen.

Bei der Berechnung der Konstanten r des neuen Massenwirkungsgesetzes lassen sich die Konstanten b der angenommenen Zustandsgleichung durch übereinstimmende Volume (beispielsweise Schmelzpunkts‐ oder Siedepunktsvolume) ersetzen.
Über Wasserstoff‐ und Kohlendioxydaufnahme durch pyrophorisches Eisen, Nickel und Kobalt
Authors: Nikitin N.
Published: January 2005

Der Mangel an genauen Angaben über die Oberflächengrößen verschiedener feinverteilter Metallpulver läßt keine sichere Vergleichung ihrer Aufnahmefähigkeit in bezug auf die Gase zu. Die Oberflächengröße hängt nicht nur von spezifischen Eigenschaften des gegebenen Metalls ab, sondern auch von seiner Reduktionstemperatur und den in kristallinischen Pulvern enthaltenen Beimengungen. Diese letzteren verhindern das Zusammensintern der Metallpulver. So verschiebt eine geringe Beimengung von A1203, in zu reduzierendem Eisenoxyd die Grenze des Verlustes der Pyrophorität des Eisens bis 7OO‐75O°. Künstliche Beimengung von ständigen Oxyden zu Nickeloxyd (durch gleichzeitiges Niederschlagen) muß in dieser Hinsicht bei Reduktion des letzteren für katalytische Zwecke von Nutzen sein.
Über Adsorption Nr. II. Kinetische Theorie der Gasadsorption
Authors: Magnus A.
Published: January 2005

1. Als kritische Adsorptionstemperatur C′ wurde diejenige Temperatur bezeichnet, bei der die Adsorptionswärme null wird und keine Adsorption mehr stattfindet. C′ steht in innigem Zusammenhange mit der Konstanten C von LORENZ und LANDÉ.
Bemerkungen zur Ferroeisenbestimmung
Authors: Dittler E.
Published: January 2005

Es wurde ein einfach und schnell auszuführendes Verfahren angegeben, den Sulfidschwefel der zersetzlichen Kiese zu bestimmen; Mengen von nur 0,01 g Magnetkies können bei sorgfältiger Ausführung der Versuche noch mit Sicherheit erfaßt werden. Das Verfahren kann dam dienen, die Bestimmung des metallischen Eisens und die Ferroeisenbestimmung in Meteoriten und Gesteinen sicherer au gestalten, wenn diese größere Mengen an solchen Kiesen enthalten.
Untersuchungen über die Löslichkeit des Lanthanhydroxyds
Authors: Sadolin Erik
Published: January 2005

Fällt man Lanthanhydroxyd aus einer Chloridlösung mit einer starken Base, so erhält man sogleich eine kolloidale Fällung von folgender Zusammensetzung:

x nimmt mit abnehmender Chlorid‐ und mit steigender Hydroxylionenkonzentration ab. Man erhält selbst mit einer ganz geringfügigen Basenmenge eine Fällung in Form einer Opalescenz. Lösliche basische Ionen, z. B. LaOH++, scheinen deshalb nicht gebildet zu werden.
The context of clinical judgment: The effect of resource availability on judgments of amenability to treatment in juvenile offenders
Authors: Mulvey Edward P. , Reppucci N. Dickon
Published: January 2005

Conclusion

The present study demonstrates that the contextual factors of resource availability and agency setting may have a significant, systematic relationship to assessments of potential treatment outcome. The value of this finding is not to debunk the idea of the objective clinician one more time but, instead, to provide leads regarding the possible factors worth further investigation in constructing models of clinical judgment. We are aware that clinicians do not necessarily “optimize” (Simon, 1976) when making treatment recommendations, but we know very little about the influences that structure the clinician's compromises in clinical judgment. A clearer understanding of this judgment process may come, however, as a result of applying a model that considers the clinician as a practitioner of human judgment, much of which is an adapative response to contextual influences (Hogarth, 1981; Nisbett & Ross, 1980).
Guillain‐Barré syndrome and Hodgkin's disease: Three cases with immunological studies
Authors: Lisak Robert P. , Mitchell Madeline , Zweiman Burton , Orrechio Edward , Asbury Arthur K.
Published: January 2005

A cell‐mediated autoimmune reaction to peripheral nervous system (PNS) antigens is widely held to be important in the pathogenesis of Guillain‐Barré syndrome (GBS). We report GBS in 3 patients with Hodgkin's disease in whom we were able to demonstrate partial immunosuppression using in vivo and in vitro methods. Because GBS has been associated with other conditions in which degrees of immunosuppression may ocur (organ transplantation, viral syndromes, systemic lupus erythematosus, postoperative states, and pregnancy), we suggest that under certain circumstances, partial and perhaps transient immunosuppression could serve as one contributing factor in triggering an autoimmune disease of the PNS.
Febrile convulsions caused by meningitis in young children
Authors: Ratcliffe John C. , Wolf Sheldon M.
Published: January 2005

The records of 325 children with meningitis were examined retrospectively. Of the 43 children who presented with seizures, 15 lacked signs of meningeal irritation; of these, 4 had additional sources of infection and 3 had had a prior febrile seizure. Of the 15 patients without signs of meningeal irritation, 5 were over 2 years of age; in 8, the meningitis was bacterial. The seizures were usually brief and generalized.
Encephalopathy associated with cryoprecipitable Australia antigen
Authors: Rosenberg Roger N. , Neuwelt Edward A. , Kirkpatrick Joel , Kohler Peter
Published: January 2005

A 19‐year‐old white woman with urticaria, arthralgias, and hepatitis B–associated antigen in her serum developed a progressive encephalopathy despite only mild hepatic dysfunction. The patient's serum at 4°C produced a cryoprecipitate containing the hepatitis B–associated antigen and its antibody. Serum complement levels were borderline low. At autopsy, gross and histological examination of the brain revealed only mild residual cerebral edema. Indirect immunofluorescent studies of the cerebral cortex and choroid plexus showed no evidence of immune complex deposition. The patient's progressive encephalopathy may have been related to the presence of cryoprecipitable hepatitis B antigen, a relationship not previously reported.
Polyradiculoneuropathy accompaning procainamide‐induced lupus erythematosus: Evidence for drug‐induced enhanced sensitization to peripheral nerve myelin
Authors: Sahenk Z. , Mendell J. R. , Rossio J. L. , Hurtubise P.
Published: January 2005

Factors involved in the development of an insidious polyradiculoneuropathy in association with a procainamide‐induced, lupuslike syndrome were explored. A 73‐year‐old man with this clinical syndrome had sural nerve changes consisting of loss of large myelinated fibers with evidence of remyelination and Schwann cell proliferation. The patient's lymphocytes showed marked incorporation of tritiated thymidine when cultured with either procainamide or extracts of human peripheral nerve myelin, and there was an enhanced response with the combination. We also found that procainamide‐treated rats showed acceleration of lymphocyte sensitization to peripheral nerve myelin as judged by the early development of inhibition of macrophage migration and positive skin tests to extracts of peripheral nerve myelin.

These studies suggest that procainamide can enhance lymphocyte sensitization to peripheral nerve myelin and may have predisposed this individual to development of a polyradiculoneuropathy.
The large apparent work capability of the blood‐brain barrier: A study of the mitochondrial content of capillary endothelial cells in brain and other tissues of the rat
Authors: Oldendorf William H. , Cornford Marcia E. , Brown W. Jann
Published: January 2005

Volumes of mitochondria in capillary endothelial cells were determined stereologically from electron micrographs of rat cerebellum, cerebral cortex, spinal cord, cauda equina, choroid plexus, anterior pituitary, median eminence of the hypothalamus, renal proximal tubules, skin, cardiac and skeletal muscle, lung, and renal glomerulus. The capillaries of the first four of these tissue types exhibit blood‐brain barrier (BBB) characterisitcs of permeability and capillary ultrastructure and were found to have mitochondrial contents amounting to 8 to 11% of the endothelial cytoplasmic volume. Tissues from non‐BBB regions were determined to have mitochondrial volumes of 2 to 5% of their respective cytoplasmic volumes, with a variety of capillary ultrastructures. The apparent excess metabolic work capability of the BBB suggested by this greater number of mitochondria may be related to maintenance of ion differentials between blood plasma and brain extracellular fluid, to extrachoroidal cerebrospinal fluid formation, or to maintaining the unique structural characteristics of central nervous system capillaries.
Penicillin‐induced epileptiform activity in the hippocampal in vitro preparation
Authors: Schwartzkroin Philip A. , Prince David A.
Published: January 2005

An in vitro preparation has been developed in which epileptogenesis in mammalian central nervous system tissue may be studied. Addition of sodium penicillin to the medium bathing slices of guinea pig hippocampus induced epileptiform activity similar to that seen in hippocampal penicillin foci in vivo. Epileptiform events were recorded as synchronous field potentials and correlated cellular bursts that ocurred spontaneously and could be triggered by orthodromic stimulation. Intracellular recordings revealed that bursts were generated from large depolarization shifts in some neurons, while in others, burst discharges had little underlying baseline depolarization. This finding, and the presence of fast prepotentials in penicillin‐treated preparations, suggested the involvement of dendritic activity in generation of epileptiform discharges.
Importance of holter monitoring in patients with periodic cerebral symptoms
Authors: Jonas Sterling , Klein Irv , Dimant Jacob
Published: January 2005

Holter monitoring was used in 358 patients with symptoms of intermittent dizziness, blackout, or both. The neurological findings in all patients were normal. None manifested evidence of a pertinent arrhythmia on the one‐minute resting ECG; 8.9% of the patients demonstrated arrhythmias known to correlate with cerebral symptoms; and 11.2% demonstrated “predisposing” arrhythmias, ie, rhythms that in and of themselves may not precipitate symptoms but predispose to arrhythmias that do. The latter category included short bursts of ectopic tachycardia and intermittent short‐duration asystole. High‐frequency ectopic beats were observed in 24.6%. In almost every patient in whom intermittent arrhythmias precipitated symptoms there were many “predisposing” arrhythmias of short duration that occurred during the asymptomatic period. A comparison of 12‐ and 24‐hour recordings demonstrated an increase in pertinent arrhythmias from 13.8 to 22.7%.