bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interchannel crosstalk on the acousto‐optic tunable filter (AOTF) for network applications
Authors: Sobrinho C. S. , Lima J. L. S. , Sombra A. S. B. 
Published: October 2002

AbstractIn this paper, we present a study of the crosstalk level of an acousto‐optic tunable filter (AOTF) operating with ultrashort light pulses (2 ps). Initially, we consider the performance of the device, with several lengths, operating in the linear and nonlinear regime without loss. Given low pump power (P0 = 1 W), the crosstalk level (XL) of this device always increases with the length of the AOTF, for three different device configurations: the soliton regime, the dispersionless regime, and the linear regime. For shorter devices (L/10 < ξL < L), the soliton regime presents the lower XL. However, this behavior is reversed for longer devices, where the filter bandwidth is much shorter than the pulse bandwidth. For the dispersionless regime and low pump power, the device with length of ξL = L/10 presents the lowest XL. As one starts increasing the pump power, the XL is increases as a consequence of the increase of the switched pulse's bandwidth. One would expect that the presence of nonlinearity leads to the broadening of the pulse bandwidth associated with the self‐phase modulation and, consequently, with the increase of the XL. For high power (P0 = 9 W), the switched pulse is also presenting pulse break up. However, in the limit of high pump powers, all the devices present almost the same XL of around −1.5 dB. For the soliton regime, in all the devices there is a decrease of the XL for pump powers around 1 W, which is the energy of the fundamental soliton. For high pump powers, all devices present a second peak, where again a decrease of the XL is detected. For the ξL = L/10 device, the minimum is around 8 W. The increase of the pump power results in high‐order solitons and pulse compression; in this situation, the bandwidth of the pulse increases and we can extrapolate the bandwidth of the device, the XL as increases. The study of the effect of the XL on the AOTF, operating with ultra‐short optical solitons, provides possibilities for achieving high efficiency in ultrafast all‐optical signal processing, especially for optical switches, filters, and optical transistors. The acoustic‐optic tunable filter (AOTF) has attracted great attention in recent years, in part because it appears to be a suitable basis for multiwavelength optical cross‐connects. It is probably the only known tunable filter that is capable of selecting several wavelengths simultaneously. This capability can be used to construct a multiwavelength router. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 230–235, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10565
Structure elucidation and conformational analysis of a fused cyclopentanopyrazolidinol
Authors: Tsoleridis Constantinos A. , Stephanidou‐Stephanatou Julia 
Published: October 2002

AbstractFrom the reaction of 2‐acetylcyclopentanone with benzoylhydrazine, the cyclopentanopyrazole derivative 4 was obtained as the only product. The structural assignment of this compound and also of the hydroxypyrazoline 3, used as a model compound, was established by analysis of their NMR spectra (1H, 13C, COSY, NOESY, HETCOR and COLOC). Copyright © 2002 John Wiley & Sons, Ltd.
Solid‐state CP/MAS 13C NMR studies on conformational polymorphism in sertraline hydrochloride, an antidepressant drug
Authors: Novoselsky Artem , Glaser Robert 
Published: October 2002

AbstractThe C(2) isotropic chemical shift values in solid‐state CP/MAS 13C NMR spectra of conformational polymorphs Form I (δ 28.5) and III (δ 22.9) of (1S,4S)‐sertraline HCl (1) were correlated with a γ‐gauche effect resulting from the respective 162.6° antiperiplanar and 68.8° (+)‐synclinal C(2) C(1) N CH3 torsion angles as measured by X‐ray crystallography. The similarity of the solution‐state C(2) chemical shifts in CD2Cl2 (δ 22.8) and DMSO‐d6 (δ 23.4) with that for Form III (and other polymorphs having C(2) C(1) N CH3 (+)‐synclinal angles) strongly suggests that a conformational bias about the C(1) N bond exists for 1 in both solvents. This conclusion is supported by density functional theory B3LYP/6‐31G(d)‐calculated relative energies of C(1) N rotameric models: (kcal) 0.00 [73.8 °C(2) C(1) N CH3 torsion angle], 0.88 (168.7°), and 2.40 (−63.4°). A Boltzmann distribution of these conformations at 25 °C is estimated to be respectively (%) 80.3, 18.3, and 1.4. Copyright © 2002 John Wiley & Sons, Ltd.
Genomic imprinting and epigenetic reprogramming: Unearthing the garden of forking paths
Authors: Kierszenbaum Abraham L. 
Published: October 2002

AbstractGenomic imprinting, an epigenetic form of gene regulation, determines the parent‐dependent gene expression of marked or imprinted genes during gametogenesis and embryonic development. Imprinting involves differential allele DNA methylation in one sex cell lineage but not in the other. Egg and sperm each contributes the same DNA sequences to the zygote but epigenetic imprinting of a subset of genes determines that only one of the parent alleles are expressed relative to the parental origin. Primordial germ cells inherit biallelically imprinted genes from maternal and paternal origin and erase their imprints to start de novo monoallelic imprinting during gametogenesis. Epigenetic paternalization is an ongoing process in the mitotically‐dividing spermatogonial stem cell and derived meiotically‐dividing spermatocyte progeny to endow sperm with imprinted alleles. Epigenetic maternalization is restricted to the oocyte growth phase of folliculogenesis and is unrelated to DNA replication since it takes place while the oocyte remains in the diplotene stage of meiotic prophase I. Sperm and oocyte genomic methylation patterns depend on the activity of DNA methyltransferases (Dnmt). A variant of Dnmt1, designated Dnmt1o, accumulates in oocyte nuclei during the follicular growth phase. Dnmt3L, an isoform of Dnmt3a and Dnmt3b, but lacking enzymatic activity, interacts with Dnmt2a and Dnmt3b and is required for spermatogenesis. In the mouse early zygote, the male pronucleus is demethylated within 4 h of fertilization. Global demethylation takes place gradually up to the morula stage. In the blastocyst, de novo methylation is reestablished in the inner cell mass but not in the trophectoderm. Both the significance of genomic imprinting and the severe developmental defects caused by disrupted Dnmt activity, point to a need for a better understanding of the causes of low cloning efficiency by somatic nuclear transfer to enucleated ovulated oocyte. Mol. Reprod. Dev. 63: 269–272, 2002. © 2002 Wiley‐Liss, Inc.
Nature's ingenuity: Bypassing the classical secretory route via apocrine secretion
Authors: Hermo Louis , Jacks Duncan 
Published: October 2002

AbstractAlthough it has been suggested that epithelial cells of the male reproductive system are involved in apocrine secretion, this method of secretion is not fully understood. In the present study, apocrine secretion was investigated in epithelial principal cells lining the epididymis and vas deferens (VD) of adult mice. The tissues were fixed by cardiac vascular perfusion with glutaraldehyde for routine electron microscope (EM) analysis and Bouin's fixative for light microscope (LM) immunocytochemistry to access functional roles. In the epididymis and VD, the apex of principal cells revealed protrusions of cytoplasm referred to as apical blebs (ABs). The latter contained solely numerous free ribosomes, 20 nm vesicles and few ER cisternae, suggesting segregation of their contents. While some ABs displayed wide areas of contact with the apical principal cell cytoplasm, others showed thin stalk‐like attachment points as well as fissures at the junction of the two areas. Together with images of ABs and their contents deep in the lumen, it is suggested that ABs detach from principal cells whereupon they breakdown to release their contents therein. As ABs of the epididymis were immunoreactive for glutathione‐S‐transferases (GSTs) and ubiquitin, it is proposed that these proteins are synthesized on free ribosomes in ABs and that apocrine secretion represents the manner whereby they enter the lumen to effectively protect sperm from free radical injury and ubiquitinate proteins for degradation, respectively. ABs of the VD were immunoreactive for 3β‐HSD, suggesting that they are also capable of synthesis of steroids with their release via apocrine secretion. Taken together the data provide evidence for apocrine secretion in the adult mouse epididymis and VD that could play important roles in relation to sperm maturation, protection and viability. Mol. Reprod. Dev. 63: 394–410, 2002. © 2002 Wiley‐Liss, Inc.
Biochemical correlates of thiazolidinedione‐induced adipocyte differentiation by high‐resolution magic angle spinning NMR spectroscopy
Authors: Chen Jin‐Hong , Enloe Brian M. , Weybright Patrick , Campbell Natalee , Dorfman David , Fletcher Christopher D. , Cory D.G. , Singer Samuel 
Published: October 2002

AbstractThiazolidinediones, a class of synthetic ligands to the peroxisome proliferator‐activated receptor‐γ, induce terminal adipocyte differentiation of 3T3 F442A cells, and have already been used as alternative therapeutic agents for the treatment of liposarcoma in clinical trials. The biochemical changes occurring in the 3T3 F442A cell line and well‐differentiated liposarcoma following induction of adipocyte differentiation with the thiazolidinedione troglitazone were measured using high‐resolution magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. 3T3 F442A cell differentiation was characterized by a large accumulation of intracellular triglyceride and withdrawal from the cell cycle. Phosphatidylcholine (PTC), phosphocholine (PC), myo‐inositol, and glycerol were found to be possible biochemical markers for adipocyte differentiation induced by thiazolidenediones. The molar ratio of PTC to PC increased fourfold in differentiated 3T3 F442A cells compared to undifferentiated cells, suggesting a substantial increase in CTP:phosphocholine cytidylyltransferase activity with differentiation. A 2.8‐fold increase in the PTC:PC ratio was observed in the lipoma‐like well‐differentiated liposarcoma of three patients who were treated with troglitazone when compared to liposarcoma from patients not treated with this drug. Thus, this ratio may be an NMR‐detectable marker of troglitazone efficacy and response to differentiation therapy for liposarcoma. Magn Reson Med 48:602–610, 2002. © 2002 Wiley‐Liss, Inc.
Induction of electric fields due to gradient switching: A numerical approach
Authors: Brand Martin , Heid Oliver 
Published: October 2002

AbstractSince the first observations of peripheral nerve stimulation in MRI, it has been clear that the underlying mechanism is the activation of the nervous system by induced electric fields. However, compared to experimental investigations little work has been done on calculating these electric fields with adequate accuracy. In this article a numerical analysis of the electric fields induced by a complete whole body gradient system is presented. The calculations were carried out on three human body models of different complexities. The numerical results correlate better to the experimental observations with a body model that resembles the human body. Applying a model with inhomogeneous conductivity, numerical stability was not reached. The results were compared to the limits given in the upcoming IEC 60601‐2‐33 standard. The comparison shows that the derived peak electric fields depend substantially on the body model used, which dictates that limits have to refer to a body model that is exactly defined. Magn Reson Med 48:731–734, 2002. © 2002 Wiley‐Liss, Inc.
Interaction of high concentrations of riluzole with recombinant skeletal muscle sodium channels and adult‐type nicotinic receptor channels
Authors: Mohammadi Bahram , Lang Nicolas , Dengler Reinhard , Bufler Johannes 
Published: October 2002

AbstractRiluzole is a neuroprotective drug that modulates glutamergic transmission but also blocks the inactivated state of voltage‐gated neuronal sodium channels at very low concentrations (about 0.1 μM). After nausea, the most common adverse effect of riluzole is asthenia, which could be due to a block of muscle sodium channels or acetylcholine receptor channels. Using the patch‐clamp technique, we applied riluzole on recombinant voltage‐gated skeletal muscle sodium and adult nicotinic acetylcholine receptor channels expressed in a mammalian cell line (HEK 293). Riluzole blocked the inactivated state of voltage‐gated skeletal muscle sodium channels, shifting the midpoint of the steady‐state inactivation curve to more negative potentials, but only in comparatively high concentrations (≥ 0.1 mM). At these concentrations, riluzole also caused an open‐channel block at acetylcholine receptor channels. We conclude that riluzole has only a mild blocking effect on the inactivated state of voltage‐gated skeletal muscle sodium channels and nicotinic acetylcholine receptor channels. As the plasma concentration of riluzole in amyotrophic lateral sclerosis (ALS) patients approximates 2 μM, it seems unlikely that asthenia is caused by a block of skeletal muscle sodium channels or acetylcholine receptor channels by riluzole. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 539–545, 2002
Microdialysis and electromyography of experimental muscle fatigue in healthy volunteers and patients with mitochondrial myopathy
Authors: Axelson Hans W. , Melberg Atle , Ronquist Gunnar , Askmark Håkan 
Published: October 2002

AbstractConsecutive 60‐min microdialysis samples were taken from the tibial anterior muscle in 11 healthy subjects and 4 patients with mitochondrial myopathy before (2–3 samples) and after (3–4 samples, 2 controls and 1 patient excluded) sustained isometric foot dorsiflexions. Before exercise, mean concentrations of lactate, pyruvate, hypoxanthine, urate, aspartate, and glutamate did not significantly differ between controls and patients. After exercise, the controls showed significantly increased concentrations of lactate, pyruvate, and urate, decreased hypoxanthine, and no change in aspartate and glutamate. Similar findings were observed in the patients. Plasma lactate was unchanged. Exercise‐induced increase in integrated electromyogram amplitude and rated subjective fatigue were correlated to increased post‐exercise lactate concentrations, with no obvious difference between the groups. Microdialysis of skeletal muscle allows the detection and monitoring of biochemical changes in the interstitial space. With the exercise protocol used, however, it was not possible to demonstrate any biochemical difference between healthy controls and patients with mitochondrial myopathy. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26:520‐526, 2002
Markovian models of three‐on‐one combat involving a hidden defender
Authors: McNaught Ken R. 
Published: October 2002

AbstractIn this paper, Markovian models of three‐on‐one stochastic firefights between ground‐based weapon systems are developed. These models address a common scenario of interest to the military, but one which has been much neglected in analytic combat models, that of combat between a hidden defender and an exposed attacking force. Each combatant must detect an opponent before commencing their firing cycle, a task which is considerably more difficult for the attacker. In the models developed here, the defender detects the exposed attacking group after an exponentially distributed time interval, while each attacker has a fixed probability of detecting the defender via the flash signature produced after each shot fired by him. The utility of the approach is demonstrated by investigating what impact the introduction of a coordinated gun‐laying system for the attacking force might have, a system made possible by battlefield digitization. The method used here allows models to be developed incrementally. This and other advantages of the Markovian approach are discussed. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 627–646, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10041
13C‐NMR isotopomer distribution analysis: a method for measuring metabolic fluxes in condensation biosynthesis
Authors: Puccetti Caterina , Aureli Tommaso , Manetti Cesare , Conti Filippo 
Published: October 2002

Abstract13C NMR spectroscopy associated with the use of 13C‐enriched substrates is a powerful tool to investigate intracellular metabolism because of the wealth of information contained in the distribution of isotopes in key metabolites. A new method of using 13C label distribution measurements in carbon skeletons of metabolites to estimate metabolic fluxes through biochemical reaction networks is presented here. This method can be applied to metabolite synthesis occurring by condensation reactions of the type nA → B, where n is the number of precursor A molecules needed to synthesize one molecule of product B. NMR isotopomer distribution analysis (NMR‐IDA) involves the introduction of a 13C‐enriched precursor, and measurements of the 13C positional enrichments at just one carbon atom position of the product B via 13C NMR spectroscopy. Information on isotopomer distribution is obtained, and data are analyzed according to a mathematical model based on multinomial probability expressions to obtain the best fit between theoretical and experimental 13C label distribution. The use of the NMR‐IDA method allows for estimation of two key parameters representing the fractional flux of 13C‐enriched tracer A molecules to total precursor A pool and the fraction of product B synthesized in the presence of a 13C‐enriched source, respectively. A practical example of NMR‐IDA application to fatty acid synthesis from [(1,2 13C2)acetyl]‐L‐carnitine in cultured primary astrocytes is also presented. Copyright © 2002 John Wiley & Sons, Ltd.
Minimax problems with bitonic matrices
Authors: Hochbaum Dorit S. , Tucker Paul A. 
Published: October 2002

AbstractThe minimax problem is a new optimization problem which substitutes maximum for addition in the constraint inequalities of a linear program. We show how a problem with n variables and m constraints can be reduced to a set cover problem with nm variables and m constraints. We define the mountain property on the coefficients in each column of the constraint matrix of a minimax problem and its generalization—the bitonic property. It is shown that these are equivalent, respectively, to set cover problems with consecutive 1's in each column or circular 1's in each column thus solving the periodic scheduling problem. We present a shortest path algorithm to solve a minimax problem with the mountain property in time O(mn + log m). For bitonic matrix problems, we present an algorithm of complexity O(m2(n + log n)). The same algorithms are used to solve a set cover problem on v sets and r elements to be covered in O(v + r log r) for a problem with consecutive 1's in each column and in O(v(v + r log r)) for a problem with circular 1's in each column. We further establish that r is at least \documentclass{article}\pagestyle{empty} \begin{document}$\Omega(\sqrt{v})$\end{document} and at most O(v). We also provide an efficient algorithm for recognizing bitonic matrices in O(mn log m) time. © 2002 Wiley Periodicals, Inc.
Intraneuronal amyloid precursor protein (APP) and appearance of extracellular β‐amyloid peptide (aβ) in the brain of aging kokanee salmon
Authors: Maldonado Tammy A. , Jones Richard E. , Norris David O. 
Published: October 2002

AbstractAntibodies to human amyloid precursor protein (APP695) and beta‐amyloid peptide (Aβ1‐42) were used to determine timing of amyloidosis in the brain of kokanee salmon (Oncorhynchus nerka kennerlyi) in one of four reproductive stages: immature (IM), maturing (MA), sexually mature (SM), and spawning (SP), representing a range of aging from somatically mature but sexually immature to spawning and somatic senescence. In IM fish, immunoreactive (ir) intracellular APP occurred in 18 of 23 brain regions. During sexual maturation and aging, the number of neurons expressing APP increased in 11 of these APP‐ir regions. Aβ‐ir was absent in IM fish, present in seven regions in MA fish, moderately abundant in 15 regions in SM fish, and was most abundant in all brain regions of SP fish exhibiting Aβ‐ir. Intracellular APP‐ir was observed in brain regions involved in sensory integration, olfaction, vision, stress responses, reproduction, and coordination. Intra‐ and extracellular Aβ1‐42 immunoreactivity (Aβ‐ir) was present in all APP‐ir regions except the nucleus lateralis tuberis (hypothalamus) and Purkinje cells (cerebellum). APP‐ir and Aβ deposition increase during aging. APP‐ir is present in IM fish; Aβ‐ir usually appears first in MA or SM fish and increases in SM fish as does APP‐ir. Extracellular Aβ deposition dramatically increases between SM and SP stages (1–2 weeks) in all fish, indicating an extremely rapid and synchronized process. Rapid senescence observed in pacific salmon could make them a useful model to investigate timing of amyloidosis and neurodegeneration during brain aging. © 2002 Wiley Periodicals, Inc. J Neurobiol 53: 11–20, 2002
Postsynaptic kinase signaling underlies inhibitory synaptic plasticity in the lateral superior olive
Authors: Kotak Vibhakar C. , Sanes Dan H. 
Published: October 2002

AbstractIn the auditory system, inhibitory transmission from the medial nucleus of the trapezoid body (MNTB) to neurons of the lateral superior olivary nucleus (LSO) undergoes activity‐dependent long‐term depression, and may be associated with developmental elimination of these synapses [Sanes DH, Friauf E (2000). Review: development and influence of inhibition in the laterial superior olivary nucleus. Hear Res 147:46–58]. Although GABAB receptor activation and postsynaptic free calcium are implicated in this depression, little is known about intracellular signaling mechanisms in this or other forms of inhibitory plasticity. In this study, we asked whether the calcium dependency of inhibitory depression was associated with the activation of calcium/calmodulin‐dependent protein kinase II (CaMKII), protein kinase C (PKC), and/or cAMP‐dependent protein kinase A (PKA). Whole‐cell voltage‐clamp recordings were obtained from LSO neurons in a brain slice preparation, permitting for the selective pharmacologic manipulation of individual postsynaptic LSO neurons. Inclusion of a CaMKII antagonist (KN‐62) in the internal pipet solution blocked inhibitory synaptic depression. A second CaMKII inhibitor (autocamtide peptide fragment) significantly decreased inhibitory depression. Inclusion of a specific antagonist of protein kinase C (PKC fragment 19–36) in the internal recording solution also blocked inhibitory depression. To test involvement of a cAMP‐dependent intracellular cascade, two different manipulations were performed. Inclusion of PKA antagonists (Rp‐cAMPS or a cAMP dependent protein kinase inhibitor peptide) prevented inhibitory depression. In contrast, when a nonhydrolyzable cAMP analog (Sp‐cAMPS) was permitted to enter the postsynaptic cell, the MNTB‐evoked IPSCs became depressed in the absence of low‐frequency stimulation. Thus, three key postsynaptic kinases, CaMKII, PKC, and PKA, participate in the activity‐dependent depression of inhibitory MNTB‐LSO synapses during postnatal development. © 2002 Wiley Periodicals, Inc. J Neurobiol 53: 36–43, 2002