DIABETIC MEDICINE, Issue 1 2010
Z. Pataky
Diabet. Med. 27, 61,64 (2010) Abstract Aims, The reduction of high plantar pressure in diabetic patients with peripheral neuropathy is mandatory for prevention of foot ulcers and amputations. We used a new biofeedback-based method to reduce the plantar pressure at an at-risk area of foot in diabetic patients with peripheral neuropathy. Methods, Thirteen diabetic patients (age 60.8 ± 12.3 years, body mass index 29.0 ± 5.0 kg/m2) with peripheral neuropathy of the lower limbs were studied. Patients with memory impairment were excluded. The portable in-shoe foot pressure measurement system (PEDAR®) was used for foot offloading training by biofeedback. The learning procedure consisted in sequences of walking (10 steps), each followed by a subjective estimation of performance and objective feedback. The goal was to achieve three consecutive walking cycles of 10 steps, with a minimum of seven steps inside the range of 40,80% of the baseline peak plantar pressure. The peak plantar pressure was assessed during the learning period and at retention tests. Results, A significant difference in peak plantar pressure was recorded between the beginning and the end of the learning period (when the target for plantar pressure was achieved) (262 ± 70 vs. 191 ± 53 kPa; P = 0.002). The statistically significant difference between the beginning of learning and all retention tests persisted, even at the 10-day follow-up. Conclusions, Terminal augmented feedback training may positively affect motor learning in diabetic patients with peripheral neuropathy and could possibly lead to suitable foot offloading. Additional research is needed to confirm the maintenance of offloading in the long term. [source]

Synthesis and Characterization of Potassium Complexes Containing Terminal ,2 -Pyrazolato Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2004
Wenjun Zheng
Abstract The potassium complexes [K(,2 -3,5-R2pz)(,6 -18-crown-6)] (R = Ph, tBu; pz = pyrazolato) were prepared by treatment of 3,5-diphenylpyrazole or 3,5-di- tert -butylpyrazole with potassium hydride in the presence of 18-crown-6. These complexes contain ,6 -18-crown-6 and terminal ,2 -pyrazolato ligands, and constitute the first examples of group 1 metal complexes with this pyrazolato ligand coordination mode. In contrast to [K(,2 -3,5-Ph2pz)(,6 -18-crown-6)] and [K(,2 -3,5- tBu2pz)(,6 -18-crown-6)], the aqua complex [K(,2 -3,5-Me2pz)(H2O)(,6 -18-crown-6)] was obtained when 3,5-dimethylpyrazole was treated with potassium hydride and 18-crown-6 in the presence of a small amount of water. [K(,2 -3,5-Me2pz)(H2O)(,6 -18-crown-6)] contains an ,2 -pyrazolato ligand that is bent towards being co-facial with the best plane of the 18-crown-6 ligand, to allow hydrogen bonding between the pyrazolato ligand nitrogen atoms and the coordinated aqua ligand. The hydrogen bonding thus confers a novel terminal ,-facial ,2 -bonding mode to the pyrazolato ligand. All compounds were characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

An Efficient and General Microwave-Assisted Copper-Catalyzed Conia-Ene Reaction of Terminal and Internal Alkynes Tethered to a Wide Variety of Carbonucleophiles

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
Sonia Montel
Abstract This paper describes a highly efficient, microwave-assisted, Conia-ene reaction of alkynes bearing a stabilizing carbon nucleophile. The reaction, catalyzed by a commercially available copper catalyst, proceeds under neutral conditions and is generally applicable even to less reactive nucleophiles such as malonate, cyanoacetate, and sulfonylacetate derivatives. This copper-mediated cycloisomerization is also applicable to internal unactivated alkynes leading exclusively to the corresponding 5-membererd products having an E -olefinic chemistry. [source]

Terminal and transient drop rise velocity of single toluene droplets in water

AICHE JOURNAL, Issue 1 2010
Mirco Wegener
Abstract The knowledge of the drop rise velocity in dispersed systems is of fundamental importance. Especially, the residence time is needed for calculation of mass transfer rates in extraction columns. This work deals with fluid dynamic measurements of toluene droplets rising in water ranging from 1.0 to 7.0 mm, with the premise of high purity of the used chemicals. The toluene/water-system is widely used as a test system with high interfacial tension. A semiempirical correlation for pure systems to predict the terminal velocity of single rising/falling droplets based on experimental data is presented. Results show that a distinction between maximum and characteristic mean values of the drop rise velocity is necessary, especially in the diameter range 2.4,3.0 mm where unexpected velocity fluctuations occur. Two distinct terminal rise velocities were observed for 3 mm droplets. Furthermore, comparisons of the Weber-Reynolds-correlation and the drag coefficient with correlations from literature show good agreement. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Model development for semicontinuous production of ethylene and norbornene copolymers having uniform composition

AICHE JOURNAL, Issue 3 2009
Shaojie Liu
Abstract Terminal and penultimate models for controlling copolymer composition distribution (CCD) in ethylene and norbornene (NB) copolymerization were developed by taking into account the variation of active site concentration with the initial comonomer ratio. The models were validated by batch polymerization experimental data. The terminal model gave better correlation with the composition data whereas the penultimate model had a better fit to the rate data. The terminal model was then used to design NB feeding policies in semicontinuous processes for targeted CCD profiles. Based on the model results, a series of ethylene-NB copolymers with various NB contents were prepared. With the same NB content, the semicontinuous process produced a uniform composition, whereas the batch process yielded broad CCD. The batch samples had lower Tg values and broader transition ranges, even yielded crystalline materials. In contrast, the semicontinuous samples overcame the disadvantages. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Bernoullian, Terminal, Penultimate or Third Order Markov Statistics?

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2005
Frederik G. Karssenberg
Abstract Summary: A series of 7 homogeneous ethylene-propylene copolymers is modeled by a Bernoullian, a terminal, a penultimate and a third order Markov model and it is found that the penultimate model describes this series best. The Bernoullian and terminal model prove to be insufficient and the third order Markov model is statistically not justified. Based on these results, a criterion to select the optimal Markovian order of homogeneous, single site catalyst produced copolymers is developed. Schematic of the [(3-MePh)(4-MePh)C(2,7-di- tert -BuFlu)(Cp)]ZrCl2 metallocene copolymerizing ethene and propene. [source]

Ethnic Differences in Pain Among Outpatients with Terminal and End-Stage Chronic Illness

PAIN MEDICINE, Issue 3 2005
Michael W. Rabow MD
ABSTRACT Objective., To explore ethnic and country of origin differences in pain among outpatients with terminal and end-stage chronic illness. Design., Cohort study within a year-long trial of a palliative care consultation. Setting., Outpatient general medicine practice in an academic medical center. Patients., Ninety patients with advanced congestive heart failure, chronic obstructive pulmonary disease, or cancer, and with a prognosis between 1 and 5 years. Outcome Measures., Patients' report of pain using the Brief Pain Inventory and analgesic medications prescribed by primary care physicians. Differences in pain report and treatment were assessed at study entry, at 6 and 12 months. Results., The overall burden of pain was high. Patients of color reported more pain than white patients, including measures of least pain (P = 0.02), average pain (P = 0.05), and current pain (P = 0.03). No significant ethnic group differences in pain were found comparing Asian, black, and Latino patients. Although nearly all patients who were offered opioid analgesics reported using them, opioids were rarely prescribed to any patient. There were no differences in pain between patients born in the U.S. and immigrants. Conclusions., Pain is common among outpatients with both terminal and end-stage chronic illness. There do not appear to be any differences in pain with regard to country of origin, but patients of color report more pain than white patients. Patients of all ethnicities are inadequately treated for their pain, and further study is warranted to explore the relative patient and physician contributions to the finding of unequal symptom burden and inadequate treatment effort. [source]

Infection of onion leaves by Alternaria porri and Stemphylium vesicarium and disease development in controlled environments

PLANT PATHOLOGY, Issue 3 2000
H. Suheri
Infection of onion by Alternaria porri and Stemphylium vesicarium was investigated under a range of controlled temperatures (4,25°C) and leaf wetness periods (0,24 h). Conidia of A. porri and S. vesicarium germinated within 2 h when incubated at 4°C. Terminal and intercalary appressoria were produced at similar frequencies at or above 10°C. The maximum number of appressoria was produced after 24 h at 25°C. Penetration of leaves by both pathogens was via the epidermis and stomata, but the frequency of stomatal penetration exceeded that of epidermal penetration. There was a strong correlation (R2 > 90%) between appressorium formation and total penetrations at all temperatures. Infection of onion leaves occurred after 16 h of leaf wetness at 15°C and 8 h of leaf wetness at 10,25°C, and infection increased with increasing leaf wetness duration to 24 h at all temperatures. Interruption of a single or double leaf wetness period by a dry period of 4,24 h had little effect on lesion numbers. Conidia of A. porri and S. vesicarium separately or in mixtures caused similar numbers of lesions. Alternaria porri and S. vesicarium are both potentially important pathogens in winter-grown Allium crops and purple leaf blotch symptoms were considered to be a complex caused by both pathogens. [source]

Fabricating Elegance: Digital Architecture's Coming of Age

ARCHITECTURAL DESIGN, Issue 1 2007
Joseph Rosa
Abstract For Joseph Rosa, John H Bryan Curator of Architecture at the Institute of Chicago, elegance with its ,refined aesthetic ability' represents a concurrent maturing of design culture and technologies. It builds on the pioneering fabrication techniques of the late 1990s, spearheaded in seminal projects such as the Korean Presbyterian Church in New York by Greg Lynn, Douglas Garofalo and Michael McInturf, and the Yokohama Port Terminal by Foreign Office Architects. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Human ovarian carcinoma cells: Histone deacetylase inhibitors exhibit antiproliferative activity and potently induce apoptosis

CANCER, Issue 12 2004
Noriyuki Takai M.D., Ph.D.
Abstract BACKGROUND Histone deacetylase inhibitors (HDACIs) can inhibit proliferation, stimulate apoptosis, and induce cell cycle arrest in malignant cells. METHODS The authors investigated the effects of four HDACIs on nine ovarian carcinoma cell lines in vitro and in vivo. Ovarian carcinoma cells were treated with a variety of HDACIs, and their effects on cell growth, the cell cycle, apoptosis, and related events were investigated. The ability of valproic acid (VPA) to inhibit the growth of ovarian tumors in immunodeficient mice was also assessed. RESULTS Clonogenic assays showed that all ovarian carcinoma cell lines were sensitive to the growth-inhibitory effects of the HDACIs. Cell cycle analysis indicated that their exposure to HDACIs decreased the proportion of cells in S phase and increased the proportion of cells in the G0/G1 and/or G2/M phases of the cell cycle. Terminal deoxynucleotidyltransferase-mediated uridine triphosphate end-labeling assays demonstrated that HDACIs induced apoptosis, which occurred in concert with alterations in the expression of genes related to apoptosis, cell growth, and malignant phenotype, including the activation of caspase-9 and caspase-3. Chromatin immunoprecipitation analysis revealed a notable increase in levels of acetylated histones associated with the p21 promoter after treatment with suberoylanilide bishydroxamine. In addition, in experiments involving nude mice, VPA significantly inhibited human ovarian tumor growth without toxic side effects. CONCLUSIONS The results of the current study suggest that HDACIs may be particularly effective in the treatment of ovarian tumors. Cancer 2004. © 2004 American Cancer Society. [source]

From Ketones, Aldehydes or Alkyl Halides to Terminal 1,1-Difluoroolefins Using BrF3.

CHEMINFORM, Issue 50 2005
Aviv Hagooly
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

An immunogold investigation of the distribution of GABA and glycine in nerve terminals on the somata of spherical bushy cells in the anteroventral cochlear nucleus of guinea pig

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2004
S. Mahendrasingam
Abstract Spherical bushy neurons in the anteroventral cochlear nucleus receive glutamatergic primary terminals from the cochlear nerve and terminals of noncochlear (i.e. nonprimary) origin, many of which colocalize gamma-aminobutyric acid (GABA) and glycine. Here the relationship between GABA and glycine in these terminals has been investigated using postembedding immunogold labelling. A significant negative correlation was found between the density of terminal labelling for GABA and for glycine in four guinea pigs. Terminals could be divided into three categories, GABA-only, glycine-only, or colocalizing depending on whether they had a significantly higher labelling density for either amino acid than the primary terminals. The overall labelling density in all four animals was significantly greater for GABA in GABA-only terminals than colocalizing ones but similar for glycine in both. Within the terminals, the labelling density over synaptic vesicles, nonvesicular regions of cytoplasm and mitochondria was also investigated. No significant difference was detected in the labelling density of vesicles compared with nonvesicular regions for either amino acid. However, a significant difference was found between the overall labelling density over mitochondria and nonvesicular regions for both. There was also significantly more mitochondrial GABA labelling in GABA-only terminals compared to colocalizing terminals but mitochondrial glycine labelling was similar in glycine-only and colocalizing terminals. Thus the level of GABA is higher in single than in colocalizing terminals, particularly in the mitochondria, but similar for glycine in both. It is possible therefore that the presence of glycine affects the level of GABA in the nonprimary terminals but that the presence of GABA does not affect the level of glycine. [source]

Two Mechanisms of Synaptic Vesicle Recycling in Rat Brain Nerve Terminals

JOURNAL OF NEUROCHEMISTRY, Issue 4 2000
Michael A. Cousin
Abstract: KCl and 4-aminopyridine (4-AP) evoke glutamate release from rat brain cortical nerve terminals by voltage clamping or by Na+ channel-generated repetitive action potentials, respectively. Stimulation by 4-AP but not KCl is largely mediated by protein kinase C (PKC). To determine whether KCl and 4-AP utilise the same mechanism to release glutamate, we correlated glutamate release with release of the hydrophobic synaptic vesicle (SV) marker FM2-10. A strong correlation was observed for increasing concentrations of KCl and after application of phorbol 12-myristate 13-acetate (PMA) or staurosporine. The parallel increase in exocytosis measured by two approaches suggested it occurred by a PKC-independent mechanism involving complete fusion of SVs with the plasma membrane. At low concentrations of 4-AP, alone or with staurosporine, glutamate and FM2-10 release also correlated. However, higher concentrations of 4-AP or of 4-AP plus PMA greatly increased glutamate release but did not further increase FM2-10 release. This divergence suggests that 4-AP recruits an additional mechanism of release during strong stimulation that is PKC dependent and is superimposed upon the first mechanism. This second mechanism is characteristic of kiss-and-run, which is not detectable by styryl dyes. Our data suggest that glutamate release in nerve terminals occurs via two mechanisms: (1) complete SV fusion, which is PKC independent; and (2) a kiss-and-run-like mechanism, which is PKC dependent. Recruitment of a second release mechanism may be a widespread means to facilitate neurotransmitter release in central neurons. [source]

Electrophysiological Identification of the Functional Presynaptic Nerve Terminals on an Isolated Single Vasopressin Neurone of the Rat Supraoptic Nucleus

JOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2010
T. Ohbuchi
Release of arginine vasopressin (AVP) and oxytocin from magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) is under the control of glutamate-dependent excitation and GABA-dependent inhibition. The possible role of the synaptic terminals attached to SON neurones has been investigated using whole-cell patch-clamp recording in in vitro rat brain slice preparations. Recent evidence has provided new insights into the repercussions of glial environment modifications on the physiology of MNCs at the synaptic level in the SON. In the present study, excitatory glutamatergic and inhibitory GABAergic synaptic inputs were recorded from an isolated single SON neurone cultured for 12 h, using the whole-cell patch clamp technique. Neurones expressed an AVP-enhanced green fluorescent protein (eGFP) fusion gene in MNCs. In addition, native synaptic terminals attached to a dissociated AVP-eGFP neurone were visualised with synaptic vesicle markers. These results suggest that the function of presynaptic nerve terminals may be evaluated directly in a single AVP-eGFP neurone. These preparations would be helpful in future studies aiming to electrophysiologically distinguish between the functions of synaptic terminals and glial modifications in the SON neurones. [source]

Actions of Acute and Chronic Ethanol on Presynaptic Terminals

ALCOHOLISM, Issue 2 2006
Marisa Roberto
This article presents the proceedings of a symposium entitled "The Tipsy Terminal: Presynaptic Effects of Ethanol" (held at the annual meeting of the Research Society on Alcoholism, in Santa Barbara, CA, June 27, 2005). The objective of this symposium was to focus on a cellular site of ethanol action underrepresented in the alcohol literature, but quickly becoming a "hot" topic. The chairs of the session were Marisa Roberto and George Robert Siggins. Our speakers were chosen on the basis of the diverse electrophysiological and other methods used to discern the effects of acute and chronic ethanol on presynaptic terminals and on the basis of significant insights that their data provide for understanding ethanol actions on neurons in general, as mechanisms underlying problematic behavioral effects of alcohol. The 5 presenters drew from their recent studies examining the effects of acute and chronic ethanol using a range of sophisticated methods from electrophysiological analysis of paired-pulse facilitation and spontaneous and miniature synaptic currents (Drs. Weiner, Valenzuela, Zhu, and Morrisett), to direct recording of ion channel activity and peptide release from acutely isolated synaptic terminals (Dr. Treistman), to direct microscopic observation of vesicular release (Dr. Morrisett). They showed that ethanol administration could both increase and decrease the probability of release of different transmitters from synaptic terminals. The effects of ethanol on synaptic terminals could often be correlated with important behavioral or developmental actions of alcohol. These and other novel findings suggest that future analyses of synaptic effects of ethanol should attempt to ascertain, in multiple brain regions, the role of presynaptic terminals, relevant presynaptic receptors and signal transduction linkages, exocytotic mechanisms, and their involvement in alcohol's behavioral actions. Such studies could lead to new treatment strategies for alcohol intoxication, alcohol abuse, and alcoholism. [source]

Activity of nAChRs containing ,9 subunits modulates synapse stabilization via bidirectional signaling programs

DEVELOPMENTAL NEUROBIOLOGY, Issue 14 2009
Vidya Murthy
Abstract Although the synaptogenic program for cholinergic synapses of the neuromuscular junction is well known, little is known of the identity or dynamic expression patterns of proteins involved in non-neuromuscular nicotinic synapse development. We have previously demonstrated abnormal presynaptic terminal morphology following loss of nicotinic acetylcholine receptor (nAChR) ,9 subunit expression in adult cochleae. However, the molecular mechanisms underlying these changes have remained obscure. To better understand synapse formation and the role of cholinergic activity in the synaptogenesis of the inner ear, we exploit the nAChR ,9 subunit null mouse. In this mouse, functional acetylcholine (ACh) neurotransmission to the hair cells is completely silenced. Results demonstrate a premature, effusive innervation to the synaptic pole of the outer hair cells in ,9 null mice coinciding with delayed expression of cell adhesion proteins during the period of effusive contact. Collapse of the ectopic innervation coincides with an age-related hyperexpression pattern in the null mice. In addition, we document changes in expression of presynaptic vesicle recycling/trafficking machinery in the ,9 null mice that suggests a bidirectional information flow between the target of the neural innervation (the hair cells) and the presynaptic terminal that is modified by hair cell nAChR activity. Loss of nAChR activity may alter transcriptional activity, as CREB binding protein expression is decreased coincident with the increased expression of N-Cadherin in the adult ,9 null mice. Finally, by using mice expressing the nondesensitizing ,9 L9,T point mutant nAChR subunit, we show that increased nAChR activity drives synaptic hyperinnervation. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source]

Electron microscopic 3D-reconstruction of dendritic spines in cultured hippocampal neurons undergoing synaptic plasticity

DEVELOPMENTAL NEUROBIOLOGY, Issue 7 2008
Wladimir Ovtscharoff Jr.
Abstract Dendritic spines are assumed to constitute the locus of neuronal plasticity, and considerable effort has been focused on attempts to demonstrate that new memories are associated with the formation of new spines. However, few studies that have documented the appearance of spines after exposure to plasticity-producing paradigms could demonstrate that a new spine is touched by a bona fida presynaptic terminal. Thus, the functional significance of plastic dendritic spine changes is not clearly understood. We have used quantitative time lapse confocal imaging of cultured hippocampal neurons before and after their exposure to a conditioning medium which activates synaptic NMDA receptors. Following the experiment the cultures were prepared for 3D electron microscopic reconstruction of visually identified dendritic spines. We found that a majority of new, 1- to 2-h-old spines was touched by presynaptic terminals. Furthermore, when spines disappeared, the parent dendrites were sometime touched by a presynaptic bouton at the site where the previously identified spine had been located. We conclude that new spines are most likely to be functional and that pruned spines can be transformed into shaft synapses and thus maintain their functionality within the neuronal network. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008. [source]

Mitochondrial clustering at the vertebrate neuromuscular junction during presynaptic differentiation

DEVELOPMENTAL NEUROBIOLOGY, Issue 6 2006
Chi Wai Lee
Abstract During vertebrate neuromuscular junction (NMJ) development, presynaptic motor axons differentiate into nerve termini enriched in synaptic vesicles (SVs). At the nerve terminal, mitochondria are also concentrated, but how mitochondria become localized at these specialized domains is poorly understood. This process was studied in cultured Xenopus spinal neurons with mitochondrion-specific probe MitoTracker and SV markers. In nerve-muscle cocultures, mitochondria were concentrated stably at sites where neurites and muscle cells formed NMJs, and mitochondria coclustered with SVs where neurites were focally stimulated by beads coated with growth factors. Labeling with a mitochondrial membrane potential-dependent probe JC-1 revealed that these synaptic mitochondria were with higher membrane potential than the extrasynaptic ones. At early stages of bead-stimulation, actin-based protrusions and microtubule fragmentation were observed in neurites at bead contact sites, suggesting the involvement of cytoskeletal dynamics and rearrangement during presynaptic differentiation. Treating the cultures with an actin polymerization blocker, latrunculin A (Ltn A), almost completely abolished the formation of actin-based protrusions and partially inhibited bead-induced mitochondrial and SV clustering, whereas the microtubule disrupting agent nocodazole was ineffective in inhibiting the clustering of mitochondria and SVs. Lastly, in contrast to Ltn A, which blocked bead-induced clustering of both mitochondria and SVs, the ser/thr phosphatase inhibitor okadaic acid inhibited SV clustering but not mitochondrial clustering. These results suggest that at developing NMJs, synaptogenic stimuli induce the clustering of mitochondria together with SVs at presynaptic terminals in an actin cytoskeleton-dependent manner and involving different intracellular signaling molecules. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source]

Synaptic plasticity and functionality at the cone terminal of the developing zebrafish retina

DEVELOPMENTAL NEUROBIOLOGY, Issue 3 2003
Oliver Biehlmaier
Abstract Previous studies have analyzed photoreceptor development, some inner retina cell types, and specific neurotransmitters in the zebrafish retina. However, only minor attention has been paid to the morphology of the synaptic connection between photoreceptors and second order neurons even though it represents the transition from the light sensitive receptor to the neuronal network of the visual system. Here, we describe the appearance and differentiation of pre- and postsynaptic elements at cone synapses in the developing zebrafish retina together with the maturation of the directly connecting second order neurons and a dopaminergic third order feedback-neuron from the inner retina. Zebrafish larvae were examined at developmental stages from 2 to 7dpf (days postfertilization) and in the adult. Synaptic maturation at the photoreceptor terminals was examined with antibodies against synapse associated proteins. The appearance of synaptic plasticity at the so-called spinule-type synapses between cones and horizontal cells was assessed by electron microscopy, and the maturation of photoreceptor downstream connection was identified by immunocytochemistry for GluR4 (AMPA-type glutamate receptor subunit), protein kinase ,1 (mixed rod-cone bipolar cells), and tyrosine hydroxylase (dopaminergic interplexiform cells). We found that developing zebrafish retinas possess first synaptic structures at the cone terminal as early as 3.5dpf. Morphological maturation of these synapses at 3.5,4dpf, together with the presence of synapse associated proteins at 2.5dpf and the maturation of second order neurons by 5dpf, indicate functional synaptic connectivity and plasticity between the cones and their second order neurons already at 5dpf. However, the mere number of spinules and ribbons at 7dpf still remains below the adult values, indicating that synaptic functionality of the zebrafish retina is not entirely completed at this stage of development. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 222,236, 2003 [source]

Activity alters muscle reinnervation and terminal sprouting by reducing the number of schwann cell pathways that grow to link synaptic sites

DEVELOPMENTAL NEUROBIOLOGY, Issue 4 2003
Flora M. Love
Abstract In partially denervated rodent muscle, terminal Schwann cells (TSCs) located at denervated end plates grow processes, some of which contact neighboring innervated end plates. Those processes that contact neighboring synapses (termed "bridges") appear to initiate nerve terminal sprouting and to guide the growth of the sprouts so that they reach and reinnervate denervated end plates. Studies conducted prior to knowledge of this potential involvement of Schwann cells showed that direct muscle stimulation inhibits terminal sprouting following partial denervation (Brown and Holland, 1979). We have investigated the possibility this inhibition results from an alteration in the growth of TSC processes. We find that stimulation of partially denervated rat soleus muscle does not alter the length or number of TSC processes but does reduce the number of TSC bridges. Stimulation also reduces the number of TSC bridges that form between end plates during reinnervation of a completely denervated muscle. The nerve processes ("escaped fibers") that normally grow onto TSC processes during reinnervation are also reduced in length. Therefore, stimulation alters at least two responses to denervation in muscles: (1) the ability of TSC processes to form or maintain bridges with innervated synaptic sites, and (2) the growth of axons along processes extended by TSCs. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 566,576, 2003 [source]

Presynaptic diadenosine polyphosphate receptors: Interaction with other neurotransmitter systems

DRUG DEVELOPMENT RESEARCH, Issue 1-2 2001
M. Teresa Miras-Portugal
Abstract Diadenosine polyphosphates (ApnA n = 2,6) are natural compounds that can play a neurotransmitter role in the synaptic terminals of the central nervous system. Microfluorimetric studies of [Ca2+]i in single synaptic terminals have shown the presence of specific ionotropic receptors for nucleotides and dinucleotides. These dinucleotide receptors may or may not coexist at the same terminal. Aminergic terminals from rat basal ganglia have been immunologically characterised by the presence of the vesicular monoamine transporter 2 after the functional studies. Fifty-eight percent of these terminals respond to nucleotides, and of these, 17% respond only to Ap5A. Cholinergic terminals from rat midbrain were immunologically characterised by the vesicular acetylcholine transporter. Sixty-three percent of these terminals responded to nucleotides, and of these, 22% responded only to Ap5A. The presynaptic ionotropic dinucleotide receptors can coexist not only with the ATP receptors, but also with various subtypes of nicotinic receptors. GABAergic terminals from rat midbrain were immunologically characterised by the vesicular inhibitory amino acid transporter. Fifty-nine percent of these terminals responded to nucleotides, and of these, 17% responded only to Ap5A. The presynaptic dinucleotide receptors, when stimulated, are able to induce the GABA release from synaptosomal preparations. These data clearly show the broad interaction of nucleotides and dinucleotides with other neurotransmitter systems. Drug Dev. Res. 52:239,248, 2001. © 2001 Wiley-Liss, Inc. [source]

A recursive decomposition algorithm for network seismic reliability evaluation

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2002
Jie Li
Abstract A new probabilistic analytical approach to evaluate seismic system reliability of large lifeline systems is presented in this paper. The algorithm takes the shortest path from the source to the terminal of a node weight or edge weight network as decomposition policy, using the Boolean laws of set operation and probabilistic operation principal, a recursive decomposition process then could be constructed. For a general weight network, the modified Torrieri method (NTR/T method) is introduced to combine with the suggested algorithm. Therefore, the recursive decomposition algorithm may be applied to evaluate the seismic reliability of general lifeline systems. A series of case studies, including a practical district electric power network system and a large urban water supply system, show that the suggested algorithm supplies a useful probabilistic analysis means for the seismic reliability evaluation of large lifeline systems. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Computation of locational and hourly maximum output of a distributed generator connected to a distribution feeder

ELECTRICAL ENGINEERING IN JAPAN, Issue 2 2009
Yasuhiro Hayashi
Abstract Recently, the total number of distributed generation such as photovoltaic generation systems and wind turbine generation systems connected to a distribution network has drastically increased. Distributed generation using renewable energy can reduce the distribution loss and emission of CO2. However, the distribution network with the distributed generators must be operated while maintaining the reliability of the power supply and power quality. In this paper, the authors propose a computational method to determine the maximum output of a distributed generator under operational constraints [(1) voltage limit, (2) line current capacity, and (3) no reverse flow to bank] at arbitrary connection points and hourly periods. In the proposed method, a three-phase iterative load flow calculation is applied to evaluate the above operational constraints. The three-phase iterative load flow calculation has two simple procedures: (Procedure 1) addition of load currents from the terminal node of the feeder to root one, and (Procedure 2) subtraction of voltage drop from the root node of the feeder to terminal one. In order to check the validity of the proposed method, numerical simulations are performed for a distribution system model. Furthermore, the characteristics of locational and hourly maximum output of a distributed generator connected to a distribution feeder are analyzed using several numerical examples. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 38,47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20610 [source]

Synaptic vesicle proteins under conditions of rest and activation: Analysis by 2-D difference gel electrophoresis

ELECTROPHORESIS, Issue 17 2006
Jacqueline Burré
Abstract Synaptic vesicles are organelles of the nerve terminal that secrete neurotransmitters by fusion with the presynaptic plasma membrane. Vesicle fusion is tightly controlled by depolarization of the plasma membrane and a set of proteins that may undergo post-translational modifications such as phosphorylation. In order to identify proteins that undergo modifications as a result of synaptic activation, we induced massive exocytosis and analysed the synaptic vesicle compartment by benzyldimethyl- n -hexadecylammonium chloride (BAC)/SDS-PAGE and difference gel electrophoresis (DIGE) followed by MALDI-TOF-MS. We identified eight proteins that revealed significant changes in abundance following nerve terminal depolarization. Of these, six were increased and two were decreased in abundance. Three of these proteins were phosphorylated as detected by Western blot analysis. In addition, we identified an unknown synaptic vesicle protein whose abundance increased on synaptic activation. Our results demonstrate that depolarization of the presynaptic compartment induces changes in the abundance of synaptic vesicle proteins and post-translational protein modification. [source]

Comparative proteome analysis of culture supernatant proteins from virulent Mycobacterium tuberculosis H37Rv and attenuated M. bovis BCG Copenhagen

ELECTROPHORESIS, Issue 19-20 2003
Jens Mattow
Abstract A comprehensive analysis of culture supernatant (CSN) proteins of Mycobacterium tuberculosis H37Rv was accomplished by combination of two-dimensional electrophoresis (2-DE), mass spectrometry, and N -terminal sequencing by Edman degradation. Analytical 2-DE gels resolved approximately 1250 protein spots from CSN of M. tuberculosis H37Rv, 381 of which were identified by mass spectrometry and/or Edman degradation. This study revealed 137 different proteins, 42 of which had previously been described as secreted. Comparative proteome analysis of CSN from virulent M. tuberculosis H37Rv and attenuated Mycobacterium bovis BCG Copenhagen identified 39 M. tuberculosis- specific spots containing 27 different proteins, representing candidate antigens for novel vaccines and diagnostics in tuberculosis. These included five proteins encoded by open reading frames absent from M. bovis BCG, e.g., early secretory antigen target (Esat6), as well as 22 novel differential proteins, such as acetyl-CoA C-acetyltransferase (Rv0243) and two putative Esat6-like proteins (Rv1198, Rv1793). [source]

Analysis of micronuclei in blue mussels and fish from the Baltic and North Seas

ENVIRONMENTAL TOXICOLOGY, Issue 4 2004
Janina Bar
Abstract Micronuclei (MN) were analyzed in erythrocytes of flounder (Platichthys flesus) and wrasse (Symphodus melops) and in gill cells of blue mussels (Mytilus edulis). The organisms were collected from three study stations in the Baltic Sea and from seven stations in the North Sea (Karmsund area, Norway) 4 times. The statistically significant differences obtained were related to the season, sex of the fish, and sampling locality. Higher MN frequencies were found in fish and mussels collected from the most polluted study stations in the North Sea. The same tendency could be described in the Baltic Sea; however, it was masked by the recent oil spill from the Butinge oil terminal. Our results showing higher MN frequencies in presumably what were the most polluted study locations suggest that MN tests in fish and mussels may be used for the detection of genotoxic effects in a marine environment. The endpoint is well characterized and can be easily recognized, and the technique is convenient to use in field samplings following standard procedures and protocols. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 365,371, 2004. [source]

Magnetic resonance microscopy of the equine hoof wall: a study of resolution and potential

EQUINE VETERINARY JOURNAL, Issue 5 2006
M. D. KELLER
Summary Reasons for performing study: Obtaining magnetic resonance images of the inner hoof wall tissue at the microscopic level would enable early accurate diagnosis of laminitis and therefore more effective therapy. Objectives: To optimise magnetic resonance imaging (MRI) parameters in order to obtain the highest possible resolution of the structures beneath the equine hoof wall. Methods: Magnetic resonance microscopy (MRM) was performed in front feet from 6 cadaver horses using T2 -weighted fast spin echo (FSE-T2), and T1 -weighted gradient echo (GRE-T1) sequences. Results: In T2 weighted FSE images most of the stratum medium showed no signal, however the coronary, terminal and sole papillae were visible. The stratum lamellatum was clearly visible and primary epidermal lamellae could be differentiated from dermal lamellae. Conclusion: Most structures beneath the hoof wall were differentiated. Conventional scanners for diagnostic MRI in horses are low or high field. However this study used ultra-high field scanners currently not available for clinical use. Signal-to-noise ratio (S/N) increases as a function of field strength. An increase of spatial resolution of the image results in a decreased S/N. S/N can also be improved with better coils and the resolution of high field MRI scanners will increase as technology develops and surface array coils become more readily available. Potential relevance: Although MR images with microscopic resolution were obtained ex vivo, this study demonstrates the potential for detection of lamellar pathology as it occurs. Early recognition of the development of laminitis to instigate effective therapy at an earlier stage and may improve the outcome for laminitic horses. Clinical MR is now readily available at 3 T, while 4 T, 7 T and 9 T systems are being used for human whole body applications. [source]

Complexes of the Bicyclic Multifunctional Sulfur-Nitrogen Ligand F3CCN5S3 with Co2+, Zn2+, Cu2+, and Cd,

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2005
Carsten Knapp
Abstract The ability of the sulfur-nitrogen-carbon bicycle F3CCN5S3 to act as a donor towards transition metal cations has been investigated. F3CCN5S3 forms complexes with [M(SO2)2](AsF6)2 [M = Co, Cu, Zn, Cd] in the ratio 2:1 of the composition [M(F3CCN5S3)2(OSO)2(FAsF5)2] [M = Co (1), Zn (3)], [Cu(F3CCN5S3)2(,-F)(,-F2AsF4)]2 (4), and [Cd(F3CCN5S3)(,-F3CCN5S3)(,2 -F2AsF4)2]2 (5) in liquid sulfur dioxide. In the octahedral Co and Zn complexes F3CCN5S3 coordinates as a monodentate ligand through the bridging nitrogen atom N5, which carries the highest negative charge according to theoretical calculations. With Cu2+ a dinuclear structure with a central planar, four-membered Cu2F2 ring is formed, which has the shortest Cu···Cu distance of all structurally characterized Cu2F2 units. Similar to the Co and Zn complexes, F3CCN5S3 acts as a terminal monodentate ligand in the Cu compound. The reaction with the larger and softer Cd2+ cation results in a dinuclear complex that contains terminal and bridging F3CCN5S3 ligands. The bridging ligands coordinate through N5 and a nitrogen atom neighboring the carbon atom. In addition, a third weak bonding interaction between one fluorine atom of the trifluoromethyl substituent and the Cd2+ center is observed. The formation of the different structures and the versatile coordination modes of the F3CCN5S3 ligand are discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Di-2-pyridyl Ketone Oxime in Zinc Chemistry: Inverse 12-Metallacrown-4 Complexes and Cationic Pentanuclear Clusters

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2005
Maria Alexiou
Abstract The use of di-2-pyridyl ketone oxime (Hpko)/X, "blends" (X, = PhCO2,, N3,, NCO,, acac,, NCS,) in zinc chemistry yields neutral tetranuclear and cationic pentanuclear clusters. Various synthetic procedures have led to the synthesis of compounds [Zn4(OH)2(O2CPh)2(pko)4]·3MeCN (1·3MeCN), [Zn4(OH)2(N3)2(pko)4]·4DMF (2·4DMF), [Zn4(OH)2(NCO)2(pko)4]·3DMF·H2O (3·3DMF·H2O), [Zn4(OH)2(acac)2(pko)4]·4CH2Cl2 (4·4CH2Cl2), [Zn5Cl2(pko)6][ZnCl(NCS)3]·2.5H2O·1.5MeOH (5·2.5H2O·1.5MeOH) and [Zn5(NCS)2(pko)6(MeOH)][Zn(NCS)4]·2.5H2O·MeOH (6·2.5H2O·MeOH). The structures of the six complexes have been determined by single-crystal X-ray crystallography. The tetranuclear molecules of 1,4 lie on a crystallographic inversion centre and have an inverse 12-metallacrown-4 topology. Two triply bridging hydroxides are accommodated in the centre of the metallacrown ring. The pko, ligands form a propeller configuration that imposes absolute stereoisomerism with , and , chirality. Two metal ions are in distorted O2N4 octahedral environments, whereas the rest are in severely distorted tetrahedral or trigonal bipyramidal environments. The five Zn ions of the cations of 5 and 6 are held together by six pko, ligands which adopt three different coordination modes; the chloro (5) and isothiocyanato (6) ligands are terminal. The five Zn ions define two nearly equilateral triangles sharing a common apex, and the novel Zn5 topology can be described as two "collapsed" 9-metallacrown-3 structures sharing a common Zn apex. Besides the pentanuclear cations, the structures of 5 and 6 contain slightly distorted tetrahedral [ZnCl(NCS)3]2, and [Zn(NCS)4]2, ions, respectively, with the isothiocyanato ligands binding the metal ion in a virtually linear fashion. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]