bluuebunny/crossref_metadata_2025_split huggingface dataset:
SiO compound formation by oxygen ion implantation into silicon
Authors: Hensel E. , Wollschläger K. , Schulze D. , Kreissig U. , Skorupa W. , Finster J. 
Published: December 2004

AbstractHigh dose oxygen ion implantation into silicon at 30 keV was performed to produce understoichiometric and stoichiometric surface oxide layers of ∼160 nm thickness. The oxygen depth profile and oxide stoichiometry was determined by RBS and XPS. SiO compound formation was found by IR spectroscopy and XPS in the unannealed samples as well as after target heating, furnace or flash lamp annealing. As implanted understoichiometric layers consist of random bonding like SiOx (O < x < 2), demixing into Si and SiO2 after annealing. Unannealed stoichiometric layers are bond strained SiO2. The activation energies of demixing and of the annealing of bond strains are determined to 0.19 and 0.13 eV, respectively. The removing of bond strains occurs at temperatures ≥800 °C in a time shorter than 1 s. The SiO2/Si transition region of unannealed stoichiometric layers consists of SiOx with an extent of about 10 nm. After annealing this extent diminishes to 0.8–1 nm in consequence of oxidation by excess oxygen from the overstoichiometric oxide region. This thickness is comparable with that of thermal oxide.
Quantitative analysis of impurities in HgCdTe using secondary ion mass spectrometry
Authors: Lapides L. E. 
Published: December 2004

AbstractSIMS has been used to analyze impurities in epitaxial layers of HgCdTe because of its sensitivity to trace impurities and because it makes it possible to obtain impurity concentration profiles through the thickness of the epitaxial layer. The impurity profiles are quantified using relative sensitivity factors calculated from ion implantation profiles obtained on standard reference samples. Unintentional impurities, such as Cu, and low‐level deliberately added impurities, such as As, In, and Ag, have been analyzed. Specialized techniques such as molecular ion spectrometry (As analysis with TeAs−) and secondary ion acceleration voltage offset (Ag analysis) have been applied to improve sensitivity and decrease background signals. The use of these techniques has allowed the establishment of detection limits of less than 0.1 parts per billion atomic (3 × 1015 cm−3). The error in the analyses is, in general, estimated to be less than ±50%. Results from relative sensitivity factor measurements and impurity profiles are presented, and detection limits and accuracy of impurity analysis in HgCdTe using SIMS are discussed.
Dependence of SERS signal on surface roughness
Authors: Kruszewski Stefan 
Published: December 2004

AbstractThe roughness of the silver electrode was changed by variation of parameters of the oxidation–reduction procedure. The roughness size has been estimated qualitatively from the angle distribution of elastically scattered light. Quantitatively measurement of roughness by scanning electron microscopy and transmission electron microscopy also have been performed. Investigations of surface‐enhanced Raman scattering (SERS) intensity as a function of parameters of oxidation‐reduction cycle procedure and electrode roughness have been performed. The experimentally observed relationship between the roughness size and SERS signal is compared with the predictions of the classical electromagnetic enhancement model.
Void formation at silicon nitride/silicon interfaces studied by variable‐energy positrons
Authors: Halec Andrzej , Schultz Peter J. , Boudreau Marcel , Boumerzoug Mohamed , Mascher Peter , McCaffrey John P. , Jackman T. E. 
Published: December 2004

AbstractVariable‐energy positrons (VEP) were used to study the deppth distribution of defects in SiNx/Si structures fabricated using ditertiary butyl silane (CONSI 4000) as the silicon precursor in an electron cyclotron resonance plasma chemical vapour deposition system. Films were grown to thicknesses ranging from 500 to 3500 Å at substrate temperatures between room temperature and 400°C and under various plasma conditions. The VEP results give evidence for differing concentrations of very large open‐volume defects at several of the SiNx/Si interfaces, confirmed by transmission and scanning electron microscopy. Their presence was correlated with non‐reactive organosilicon adsorption on the substrates prior to the thin film deposition.
Dual signaling mechanisms of estrogen: Phosphorylation of P53 at Ser15 in aging HMEC in the absence of estrogen receptor
Authors: Hass Ralf , von Wasielewski Reinhard , Fazekas Ursula , Bartels Helmut , Jans Erik , Lück Hans‐Joachim 
Published: December 2004

AbstractPrimary cultures of human mammary epithelial cells (HMEC) ex vivo underwent significant morphological and functional changes during the process of aging. Cells in S phase significantly declined after 19 d and accumulated in G0/G1 and G2/M phase after 50 d. Simultaneously, the initial estrogen receptor expression of 32,3% dropped to less than 1% in 19 d and 50 d aged HMEC, respectively. Estrogen treatment of HMEC demonstrated unaltered levels of P53 and phosphorylated P53 after 60 min. After 24 h of estrogen treatment, however, Western blot analysis revealed a significantly enhanced phosphorylation of P53 at Ser15 in 5 d and 19 d HMEC populations, respectively. A phospho‐P53 ELISA confirmed a significant Ser15‐phosphorylation of P53 in both HMEC populations following 24 h of estrogen stimulation, but no significant changes after 60 min, respectively. According to the estrogen receptor depletion in 19 d aged HMEC, these data indicated a receptor‐independent estrogen signaling.
Effects of fimbria‐fornix transection and ganglioside treatments on histochemical staining for glucose‐6‐phosphate dehydrogenase in the lateral septum
Authors: Fass Barry , Stein Donald G. 
Published: December 2004

AbstractThe present study examined whether ganglioside treatments would affect an enzyme marker (glucose‐6‐phosphate dehydrogenase; G6PDH) of neural metabolism in an established model system (the hippocamposeptal projection) of deafferentation and sprouting. Rats were subjected to unilateral transections of the fimbria‐fornix (FF) in order to (1) interrupt the hippocamposeptal projection, (2) deafferent the lateral septal nucleus (LSN) ipsilaterally, and (3) induce sprouting by the contralateral FF.In untreated rats which were killed at 2–4 days postlesion, histochemical staining for G6PDH was reduced by 35–40% in the deafferented LSN relative to the contralateral side. However, at 6–8 days (i.e., when sprouting begins), staining intensity returned toward contralateral values (i.e., recovered). This pattern of changes in G6PDH staining was not observed in the caudate nucleus adjacent to the LSN.In ganglioside‐treated rats which were killed at 4 days, there was a significantly smaller reduction of G6PDH staining in the deafferented LSN (23%; P=.05). This effect was not observed in the LSN of treated rats killed at 2 days, nor in the caudate nucleus at either time point.The present data indicate that (1) FF transection results in a reduction and subsequent recovery of G6PDH staining in the deafferented LSN; and (2) ganglioside treatments may accelerate the onset of the recovery of G6PDH activity. We suggest that gangliosides' effect on G6PDH reflects an acute enhancement of biosynthetic events in deafferented neurons.
The serotoninergic innervation of cerebral cortex: Different classes of axon terminals arise from dorsal and median raphe nuclei
Authors: Kosofsky Barry E. , Molliver Mark E. 
Published: December 2004

AbstractThe objective of the present study was to characterize the morphology of serotoninergic axons in cerebral cortex of the rat and to determine whether dissimilar axon terminals arise from the dorsal vs. the median raphe nuclei. The anterograde tracer PHA‐L was administered by iontophoresis into the dorsal (DR) and median (MR) raphe nuclei, and the morphologic features of the respective axonal projections from raphe to forebrain were analyzed. We have observed consistent structural differences between the axons from these two nuclei. Anterogradely labeled axons which arise from cells in the MR are characterized by large, spherical varicosities (type M axons) and by variations in axonal diameter. In contrast, DR fibers are very fine and typically have small, pleomorphic varicosities that are granular or fusiform in shape (type D axons). Similar features of serotonin (5‐HT) axon morphology are also evident in 5‐HT immunocytochemical preparations. In addition to structural differences, there is differential topographic distribution of MR vs. DR fibers, with MR axons concentrated in particular areas of limbic cortex such as dentate gyrus, posterior cingulate, and entorhinal areas as well as in parietal cortex. Immunofluorescence with dual labels shows that over two‐thirds of the raphe‐cortical axons are serotoninergic. The dissimilarities in axon morphology indicate that individual raphe nuclei may form different patterns of synaptic organization. Based on the evidence that the dorsal and median raphe nuclei give rise to morphologically different axon terminals, we conclude that 5‐HT axons in cortex may be subdivided into two distinct projections. This proposal is in accord with other, recent data showing that the two axon types have different pharmacologic properties and are likely to be functionally different.
On the distribution of cholecystokinin receptor binding sites in the human brain: An autoradiographic study
Authors: Dietl Monika M. , Probst Alphonse , Palacios José M. 
Published: December 2004

AbstractCholecystokinin (CCK) binding sites were localized by in vitro autoradiography in human postmortem brain materials from 12 patients without reported neurological diseases using [125I]Bolton‐Hunter CCK octapeptide (BHCCK‐8) as a ligand. The pharmacological characteristics of BHCCK‐8 binding to mounted tissue section were comparable to those previously reported in the rat. CCK‐8 being the most potent displacer, followed by caerulein, CCK‐4, and gastrin I. The distribution of BHCCK‐8 binding sites was heterogeneous. These sites were highly concentrated in a limited number of gray matter areas and nuclei. The highest binding densities were seen in the glomerular and external plexiform layers of the olfactory bulb. BHCCK‐8 binding sites were also enriched in the neocortex, where they presented a laminar distribution with low levels in lamina I, moderate concentration in laminae II to IV, high density in lamina V, and low levels in lamina VI. A different laminar distribuition was seen in the visual cortex, where a low receptor density was observed in lamina IV but higher density in laminae II and VI. In the basal ganglia the nucleus accumbens, caudatus, and the putamen presented moderate to high densities of binding sites, while the globus pallidus lacked sites of BHCCK‐8 binding. In the limbic system the only area presenting moderate to high density was the amygdaloid complex, particularly in the granular nucleus, while most of the thalamic nuclei were extremely poor or lacked BHCCK‐8 binding. The hippocample formation showed low (CA1‐3) to moderate (subiculum) densities. Midbrain areas generally disclosed very low levels of BHCCK‐8 binding sites. The pontine gray and the nucleus reticularis tegmenti pontis showed a relatively high density of CCK‐8 receptor specific binding. Moderate to very high densities were found in few nuclei of the lower brainstem and spinal cord as the inferior olives and their accessory nuclei, the arcuate nuclei, the striae medullares, the efferent (motor) nucleus of the vagus, and the substantia gelatinosa of the cervical and thoracis spinal cord.These results are discussed in relation to the distribution of endogenous peptide and to the known physiological and pharmacological effects of substances acting of on these receptors.
In vitro studies of the role of γ‐aminobutyric acid in inhibition in the lateral septum of the rat
Authors: Stevens David R. , Gallagher Joel P. , Shinnick‐Gallagher Patricia 
Published: December 2004

AbstractFocal stimulation, stimulation of the fimbria, and stimulation of the medial septal area result in an inhibitory postsynaptic potential (IPSP) in lateral septal neurons. Increased stimulus intensity results in the appearance of a late hyperpolarizing potential (LHP). Treatment of the slice with bicuculline methiodide or picrotoxin results in blockade of the IPSP. When present, LHPs are enhanced in the presence of bicuculline or picrotoxin. Spontaneous and evoked IPSPs reverse near –70 mV, and LHPs reverse near –90 mV.Iontophoretic application of γ‐amino‐butyric acid (GABA) results in hyperpolarizing, depolarizing, or biphasic potentials. Treatment with bicuculline or picrotoxin results in depression of biphasic GABA responses that appears selective for the depolarizing portion of the potential. At high concentrations of bicuculline, a portion of the hyperpolarizing GABA potential persists.The reversal potential of the depolarizing GABA potential in near –30 mV, and the reversal potential of monophasic hyperpolarizing GABA potential is near –70 mV. The bicuculline‐resistant hyperpolarizing GABA response has a reversal potential near –90 mV.GABA activates three separate conductances on septal neurons, which are similar to those reported on hippocampal neurons. The resistance of the hyperpolarizing GABA potential to bicuculline appears to be due to the presence of a GABA‐activated potassium conductance, which is similar to that activated by baclofen.
Primordial synaptic structures and synaptogenesis in rat olfactory cortex
Authors: Kunkel D. D. , Westrum L. E. , Bakay R. A. E. 
Published: December 2004

AbstractMature synaptic contacts and various primordidal synaptic elements were studied, counted, and analyzed in rat olfactory cortex from birth to 30 days of age. Primordial structures possess one or a few, but not all, of the features of a true mature synapse and have been grouped into two major classes based upon type of apposition: (1) single or (2) partial and multiple, with vacant postsynaptic sites included in the latter. There is a classical fivefold increase in number of mature synapses between birth and 30 days, but different patterns in the primordial appositions are observed. It is suggested that single apposition contribute to early synapse formation, while partial and multiple appositions participate later on during a time of rapid growth of new afferents to the area. The results suggest a clear role for primordial synaptic structures in synaptogenesis; that the sequence may be more divers than originally hypothesized, occurring at different stages; and that competition, synapse elimination, and replacement may be more prevalent in normal synaptogenesis than has been previously suspected.
Cholinergic transmission at newly formed synapses made by retinal neurons in culture
Authors: Stockbridge Norman , Puro Donald G. 
Published: December 2004

AbstractThe purpose of this study was to investigate the properties of cholinergic transmission at nascent synapses formed by neurons from the embryonic chick retina. By using a cell culture system in which striated muscle cells served as postsynaptic targets for dissociated retinal neurons, it was possible to record synaptic activity soon after the establishment of a functional cholinergic synapse. Postsynaptic potentials ranged from a few hundred microvolts to greater than 10 mV. The high temperature dependence (Q10 of 10) of this cholinergic transmission indicated that the release of acetylcholine from the embryonic retinal neurons was not injury‐related. The wide range in event amplitudes did not appear to be due to electrotonic conduction from adjacent myotubes. Rather, a lack of correlation between event amplitude and rise time indicated that the release of acetylcholine occurred over a confined area of contact. Amplitude histograms of these events always showed a unimodal distribution, with small events being most common. No pattern to the timing of the events was evident. In addition, the inward current blockers, tetrodotoxin and cadmium did not affect this activity.Taken together, our findings indicate that the embryonic retinal neurons studied in this culture system spontaneously release acetylcholine in a pulsatile manner by a mechanism that is stimulus‐independent and highly temperature sensitive. A hypothesis is that the large variation in size of postsynaptic events at these newly formed synapses is caused by the spontaneous release of packets containing differing amounts of acetylcholine.
Reversible shifts in the Ca2+‐dependent release of aspartate and glutamate from hippocampal slices with changing glucose concentrations
Authors: Szerb John C. , O'Regan Patrick A. 
Published: December 2004

AbstractIt is known that low glucose concentrations increase the aspartate and decrease the glutamate content of brain tissue both in vivo and in vitro. To see whether these changes occur in the transmitter compartment or not, the release of aspartate and glutamate evoked by electrical‐field stimulation or by high K+ was followed in slices of rat hippocampus superfused with 5 or 0.2 mM glucose. Superfusion with 0.2 mM glucose increased the evoked release of aspartate about ten times and that of glutamate about threefold. This shift in the ratio of aspartate to glutamate released was accompanied by a similar increae in the relative amount of aspartate contained in the slices. The high evoked release of aspartate and glutamate was well maintained, provided 0.5 mM glutamine was added to the medium. Changing the concentration of glucose after the first period of stimulation rapidly altered the relative amounts of aspartate and glutamate released but not the enhanced release of glutamate. The large evoked release of both aspartate and glutamate in 0.2 mM glucose was almost entirely Ca2+‐dependent. The relative amounts of aspartate and glutamate released by 50 mM K+ also changed when the glucose concentration was reduced. Results suggest two effects of low glucose concentrations: an increase in the overflow of synaptically released glutamate due to a decreased uptake and an increase in the proportion of aspartate to glutamate formed and released from the transmitter pool. These observations are consistent with the interpretation that these two transmitters can be released in different proportions from the same terminals.
Calcium‐Insensitive miniature endplate potentials at the neuromuscular junction
Authors: Lupa Mark T. 
Published: December 2004

AbstractSeveral different types of acetylcholine secretion have been shown to coexist at the neuromuscular junction along with the Ca2+‐dependent quantal release producing miniature endplate potentials (mepps) and endplate potentials. One of these, the Ca2+‐insensitive, slow‐rising mepps (slow mepps), is present in normal untreated muscles but is most prominent in many conditions where the Ca2+‐dependent quantal release mechanism is not functioning properly. Slow mepps occur at a frequency of less than 0.1 Hz in normal muscles, with large variability between fibres and muscles, and can reach frequencies of 1–2 Hz in several pathological conditions. The potentials are also highly variable in size and shape, being generally of high amplitude (0.1–15 mV) and prolonged time course (1–15 ms rise time). Most importantly, slow mepps are not affected by procedures which increase the intraterminal Ca2+ > concentration, including nerve stimulation, thus being unable to contribute to the function of synaptic transmission.The cellular source of the Ca2+‐insensitive mepps has been determined to be the nerve terminal and not the Schwann cells or nerve sprouts. The release process producing slow mepps is gererally insensitive to many drugs, ions, and procedures, stimulation being observed with vinblastine, cytochalasin B, and caffeine. Depression of this secretion is effected by uncouplers of oxidative phosphorylation and by a drug (AH5183) which inhibits the vesicular active acetylcholine transport system. It is concluded that the slow mepps are due to an exocytic fusion of unique synaptic vesicles with the plasma membrane near the active zones, in a process insensitive to many intracellular ions and regulators. Since slow mepps are prominent in many pathological conditions of nerve and muscle, it is speculated that they play some role in the recovery or development of synaptic function.
Vasopressin promotes neurite growth in cultured embryonic neurons
Authors: Brinton Roberta E. , Gruener Raphael 
Published: December 2004

AbstractVasopressin (AVP) has been identified as a neural peptide which may influence memory function. Because of this action, we investigated the effect of AVP on neurons growing in culture. Vasopressin was found to markedly increase neurite outgrowth from cultured embryonic neurons and to also accelerate the rate of neuritic growth. Maximal stimulation of neurite production occurred after 24‐hour incubation in the presence of 1 μM AVP. In AVP‐treated cultures the profuse neuritic arborization was characterized by numerous microspikes along the neuritic shafts and at the perimeters of growth cones. These data provide strong evidence for a neurotrophic effect of AVP which, we suggest, may be relevant to neuronal development as well as to morphological changes which occur in the mature nervous system, possibly during memory formation.
Neurotrophic effects of GABA in cultures of embryonic chick brain and retina
Authors: Spoerri P. E. 
Published: December 2004

AbstractThe present study examined whether GABA treatments would affect the growth and development of embryonic chick cortical and retinal neurons in culture. Incubation of these cells in the presence of 10−−5 M GABA produced several responses. It promoted the proliferation and the differentiation of the neurons studied by affecting the length and branching of the neurites as well as synaptogenesis, as revealed by morphometric measures. At the ultrastructural level, GABA treatment also led to an increased density of neurotubules, rough endoplasmic reticulum (RER), Golgi apparatus, coated vesicles, and other vesicles. These data support the hypothesis that GABA functions as a trophic or regulatory factor of at least certain neuron types.
Morphometric study of synaptic patterns in the rat caudate nucleus and hippocampus under haloperidol treatment
Authors: Uranova Natalya A. , Orlovskaya Diana D. , Apel Katrin , Klintsova Anna J. , Haselhorst Uwe , Schenk Herwart 
Published: December 2004

AbstractA morphometric study of the synapses on dendritic shafts and spines was performed in the rat caudate nucleus and the CAI area of the hippocampus under chronic haloperidol treatment. In the nucleus caudatus, the synaptic density of dendritic shafts increased by 83% and those on spines by 53%. Most of the parameters measured in axospinous synapses were significantly increased: the area of presynptic axon terminals (20%), the number of mitochondria per axon terminal (51%), the length of active zone (11%), the area of postsynaptic density (23%), and the perimeter of postsynaptic density (12.5%). The area of postsynaptic spines showed no changes. In the synapses on dendritic shafts, the area of presynaptic terminals decreased (31%), the area of mitochondria per terminal decreased (40%), the lingth of active zone increased (14%), and other parameters were unchanged. There were no significant differences in the same parameters measured in the hippocampus. The data are discussed as morphological correlates of behavioral supersensitivity and dopamine D2 receptor up‐regulation.