bluuebunny/crossref_metadata_2025 huggingface dataset:
The neurotoxic effect of iron on pyramidal cell number in rat hippocampus: a stereological study
Authors: Bostanci M. Ömer , Bagirici Faruk , Korkmaz Adnan
Published: August 2003

There have been numerous studies of neuronal hyperactivity and oxidative stress induced by iron. Moreover, it has been found that iron levels in the brain are markedly increased in some neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). We attempted to identify the toxic effect of iron on the hippocampus, a region of the brain known to be involved in learning and memory processes and which lends itself to stereological analysis. Rats were given iron chloride (FeCl35H2O), 200 mM in 2.5 μl) intracortically and were killed 10 days later. The total number of neurons in the hippocampus of control and iron‐treated rats was counted with an optical fractionator. Iron administration caused a significant decrease in the total number of pyramidal neurons in the left (31.6% decrease) and right (32.2% decrease) hippocampi (p<0.001). The findings suggest that excess iron contributes to pyramidal cell death in the rat hippocampus.
L‐arginine potentiates monosynaptic and polysnaptic spinal reflexes
Authors: Tasci Niyazi , Ankarali Seyit , Demir Şerif , Canan Sinan , Marangoz Cafer
Published: August 2003

Nitric oxide (NO) is long been known to play a major role in a wide range of physiological functions as a neural messenger and a neurotransmitter.

The aim of this study was to investigate the effects of NO precursor L‐arginine on monosynaptic and polysnaptic spinal reflexes in anaesthetized and spinalized cats. A polyethylene cannula was placed into the right carotid artery in order to monitor blood pressure and a blood‐pressure‐clamp was applied between 90–110 mmHg. After a dorsal laminectomy between L5 and S1, monosynaptic and polysnaptic spinal reflexes were evoked by electrical stimulation of gastrocnemius nerves. Following control recordings, administration of NO precursor, L‐arginine in 500 μM, 1, 2, 5 mM (local) and 50, 100, 200, 500 mg/kg (i.v.) does significantly increased the monosynaptic and polysnaptic reflex amplitude in a dose dependent manner. L‐arginine appears to be more effective on polysnaptic reflexes than on monosynaptic reflexes. D‐arginine, an ineffective enantiomer of L‐ariginine was also tested as a control substance against L‐arginine and it has no effects on the monosynaptic and polysnaptic reflexes.

These results suggest that L‐arginine may play an excitatory role in modulation of spinal reflexes and this role may be mediated by NO in the cat spinal cord.
Possible involvement of nitric oxide in the modulation of photolytic flash‐induced intercellular calcium waves in cultured astrocytes
Authors: Kawahara Koichi , Iwabuchi Sadahiro
Published: August 2003

Waves of elevated intracellular free calcium that propagate between neighboring astrocytes are important for the intercellular communication between astrocytes as well as between neurons and astrocytes. In this study, intercellular calcium waves were evoked by focal photolysis of a caged calcium inophore in cultured astrocytes. The focal photolysis of the caged compound resulted in an increase of intracellular calcium in the flashed cells, and this increase then propagated to neighboring astrocytes. The evoked calcium increase was inhibited by incubating cells with an inhibitor of nitric oxide synthase as well as with a scavenger of nitric oxide (NO). In addition, treatment of cultures with an NO donor resulted in the marked enhancement of the photolytic flash‐induced calcium rise in astrocytes. This enhancement was reversed by treatment with inhibitors of soluble guanylyl cyclase as well as of protein kinase G.
Computer‐aided design of new organic transformations: exposition of the ARGENT‐1 program
Authors: Molchanova Marina S. , Tratch Serge S. , Zefirov Nikolai S.
Published: August 2003

The principles and distinctive features of ARGENT, a new software series aimed at a systematic search for novel types of organic interconversions, are described; its advantages in comparison with other reaction design programs are mentioned. The selection criteria used at different stages of the generation process are considered. Several interesting reactions proposed using ARGENT‐1, the first program of the ARGENT series, are discussed. Prospects for the further development of ARGENT are outlined. Copyright © 2003 John Wiley & Sons, Ltd.
A theoretical study of (old and new) non‐classical carbocations derived from cyclic saturated hydrocarbons
Authors: Alkorta Ibon , Abboud José Luis M. , Quintanilla Esther , Dávalos Juan Z.
Published: August 2003

Nine non‐classical carbocations derived from cyclic saturated hydrocarbons were studied by means ofab initiocalculation, MP2/6–311G**. The geometry, energetics, orbital interactions within the Natural Bond Orbital formalism, electron density and chemical shieldings were obtained and analyzed. In all cases a similar geometrical distribution (‘non‐classical moiety,’ NCM) was obtained with the carbon atoms located in a triangle with two of their sides of 1.84 Å and the third of 1.40 Å. The energetic stability of the carbocations was rationalized on the basis of the strain in the rings involved. The NBO analysis shows that the charge is largely distributed over the three centers and also the existence of a two‐electron, three‐center orbital with similar contribution of the three atoms. Electron density maps were obtained and analyzed. In all cases, the chemical shieldings of the CH2group of the NCM are in the region of saturated hydrocarbons whereas those for the CH group are similar to those found in double‐bonded systems. Copyright © 2003 John Wiley & Sons, Ltd.
Oxidative N‐debenzylation of N‐benzyl‐N‐substituted benzylamines catalyzed by horseradish peroxidase
Authors: Kim Sung Soo , Jung Hwan Kyu
Published: August 2003

N‐Benzyl‐N‐substituted benzylamines and compound I of horseradish peroxidase engender electron transfer yielding the corresponding nitrogen radical cation 1, which is simultaneously converted into 2 and 3. Subsequently, expulsion of proton and hydroxylation yielding α‐hydroxylamines are followed by the formation of benzaldehydes and benzylamines. Copyright © 2003 John Wiley & Sons, Ltd.
Antiasthmatic activity of the methanol extract of leaves of Passiﬂora incarnata
Authors: Dhawan Kamaldeep , Kumar Suresh , Sharma Anupam
Published: August 2003

The methanol extract of the leaves of P. incarnata was evaluated for its antiasthmatic effects against acetylcholine chloride (Ach)‐induced‐bronchospasm in guinea‐pigs at doses of 50, 100 and 200 mg/kg. Using a 7‐day treatment regimen, signiﬁcant prevention of dyspnoea‐related‐convulsions was noted in the animals treated with a 100 mg/kg dose of this extract. No preventive effect was exhibited by the 50 mg/kg dose and at a higher dose, i.e. 200 mg/kg, the preventive effects against Ach‐chloride‐induced‐dyspnoea were also reduced. This may be due to defective alpha‐adrenoceptor function reported after excessive or continuous administration of an alpha‐receptor agonist. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of sesquiterpene lactone fraction of Saussurea lappa on transudative, exudative and proliferative phases of inﬂammation
Authors: Damre A. A , Damre A. S. , Saraf M. N.
Published: August 2003

The sesquiterpene lactone fraction of Saussurea lappa roots was evaluated for its effect on the transudative, exudative and proliferative phases of inﬂammation using the cotton pellet granuloma assay in rats. The fraction (25–100 mg/kg, p.o.) showed signiﬁcant dose‐dependent inhibition of the increase in wet weight of the cotton pellet at 3 h (transudative phase), leakage of dye from the bloodstream around granuloma at 24 h (exudative phase) and increase in dry weight of the cotton pellet on day 6 (proliferative phase). It signiﬁcantly lowered the elevated biochemical parameters such as alkaline phosphatase, acid phosphatase, γ‐glutamyltranspeptidase and signiﬁcantly elevated the lowered albumin concentration in serum. The studies suggest that the antiinﬂammatory activity of the sesquiterpene lactone fraction of S. lappa may, in part, be due to stabilization of lysosomal membranes and an antiproliferative effect. Copyright © 2003 John Wiley & Sons, Ltd.
Antioxidant activity of Cinnamomum cassia
Authors: Lin Chun‐Ching , Wu Sue‐Jing , Chang Cheng‐Hsiung , Ng Lean‐Teik
Published: August 2003

The antioxidant activities of hot water extracts (HWECC) and ethanol extracts (EECC) from the dry bark of Cinnamomum cassia Presl were evaluated in this study. Results showed that at 1.0 mg/mL, the ethanol extracts of C. cassia (96.30%) exhibited a greater inhibition than the α‐tocopherol (93.74%) on FeCl2‐ascorbic acid induced lipid peroxidation of rat liver homogenate in vitro. From 0.05 to 1.0 mg/mL, the EECC demonstrated the highest superoxide anions scavenging activity and the strongest anti‐superoxide formation activity (p < 0.05). The same extract also showed an excellent antioxidant activity in enzymatic and nonenzymatic liver tissue oxidative systems. EECC revealed the strongest antioxidant activity followed by α‐tocopherol and HWECC. Compared to α‐tocopherol, the IC50 values of EECC were found to be lower in thiobarbituric acid test (IC50 = 0.24 mg/mL vs 0.37 mg/mL), in cytochrome c test (IC50 = 0.16 mg/mL vs 0.27 mg/mL) and in xanthine oxidase inhibition test (IC50 = 0.09 mg/mL vs 0.19 mg/mL). The present study concludes that EECC could be used as a good source of antioxidant in the dietary supplement. Copyright © 2003 John Wiley & Sons, Ltd.
Inﬂuence of ethyl acetate extract and quercetin‐3‐methyl ether from Polygonum amphibium on activation lymphocytes from peripheral blood of healthy donor in vitro
Authors: Smolarz H. D. , Surdacka A. , Roliński J.
Published: August 2003

The inﬂuence of an ethyl acetate extract from Polygonum amphibium L. and quercetin‐3‐methyl ether isolated from them were examined on the human immune system. The investigations were made on peripheral blood mononuclear cells from healthy donors. The cells were stimulated by plant extract and quercetin‐3‐methyl ether in 24 h culture and analysed in ﬂow cytometry. The following mice monoclonal antibody anti human activate markers were used: anti HLA‐DR PE, anti CD25 FITC, anti CD69 FITC and anti CD71 FITC. The level of Interleukine‐2 in blood serum and in culture supernatants was measured by ELISA method. Ethyl acetate extract from Polygonum amphibium caused the rise in the number of CD25 and HLA‐DR positive lymphocytes and increased the expression of CD25 and CD71 antigens. The level of IL‐2 was increasing for the duration of the culture, independently from the presence of stimulators. Besides quercetin‐3‐methyl ether, from herb of Polygonum amphibium L., trans‐taxifolin, quercetin and kaempferol were isolated The structure of the isolated compounds was determined by spectroscopic (UV, 1H NMR, 13C NMR and CI‐MS) methods. Copyright © 2003 John Wiley & Sons, Ltd.
Antimicrobial activity of terpenoids from Trichodesma amplexicaule Roth.
Authors: Singh B. , Singh S.
Published: August 2003

T. amplexicaule Roth. has been investigated phytochemically for biologically active constituents from the benzene extract. This yielded a mixture of terpenoids: β‐sitosterol, α‐amyrin, lupeol, hexacosanoic acid, ceryl alcohol and hexacosane. The sequential extracts, isolated terpenoids and reference antibiotics were screened for their possible bioactivities against selected pathogenic bacteria, Escherichia coli, Staphylococcus aureus and fungi, Aspergillus ﬂavus and Penicillium chrysogenum etc. Out of the sequential extracts, the benzene extract was more potent against S. aureus (IZ = 10.36) and R. phaseoli (IZ = 10.69). The inhibition zones of isolated terpenoids were also recorded and the activity index was calculated and it was found that hexacosane was more active (IZ = 13.39) against E. coli and hexacosanoic acid had greater activity against A. ﬂavus (IZ = 11.56). The present study deals with antimicrobial screening of sequential extracts and isolated terpenoids. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of some traditional plant extracts on rat oestrous cycle compared with Clomid
Authors: Benie T. , Duval J. , Thieulant M.‐L.
Published: August 2003

It is well known that the plant kingdom contains numerous bioactive substances affecting the regulation of reproduction. The present study was undertaken to examine the putative contraceptive effects of three tradi‐ tional plant extracts from Côte d'Ivoire Pharmacopea. It concerns Afrormosia laxiflora (Papilionacea), Pterocarpus erinaceus (Papilionacea) and Cola nitida (Sterculiacea) stem bark. Data showed that treatment of rats with these plant extracts induced ovulation and oestrous cycle blockade at the dioestrous II stage. The analysis of the principal hormones involved in oestrous cycle regulation showed that the plant extracts decreased gonadotropin release (both LH and FSH). In fact, A. laxiflora, P. erinaceus and C. nitida extracts inhibited gonadotropin release as an antiestrogen‐like substance. Copyright © 2003 John Wiley & Sons, Ltd.
Effect of a dysmenorrhea Chinese medicinal prescription on uterus contractility in vitro
Authors: Hsu Chun‐Sen , Yang J‐Kay , Yang Ling‐Ling
Published: August 2003

Dysmenorrhea is a common gynecologic complaint. After their ﬁrst menstrual period, 30%–60% of American women suffer from some level of discomfort. It is estimated that 6 billion work hours are lost in this manner every year in the United States which equals an economic loss of nearly US$200 million. Dysmenorrhea is not only a problem for women but also one which affects quality of life and even reduces productivity in general.

Dysmenorrhea is directly related to elevated levels of PGF2α (prostaglandins F2α) and is treated using nonsteroid anti‐inﬂammatory drugs in Western medicine. Though efﬁcacy of the latter is rapid, there are many side effects to the liver, kidney, and digestive system. The anti‐inﬂammatory effect is temporary, and such drugs are unable to provide a long‐term cure. Because of this, Chinese medicinal therapy is being considered as a feasible alternative medicine.

In this study, Wen‐Jing Tang (one of the dysmenorrhea Chinese medicinal prescriptions) was selected. A 50% alcoholic solution was used to extract active ingredients and create a freeze‐dried product. At ﬁrst, Wen‐Jing Tang was used to suppress spontaneous contractions and prostaglandins F2α‐induced contractions of rat uterine smooth muscle in vitro. Then, an assessment was performed to determine the mechanism of the prescription. Acetylcholine, ergonovine, propranolol, oxytocin, and KCl were used to analyze the physiological mechanisms of WJT. The results show that antagonism of both PGF2α and ACh are the major mechanisms for treating dysmenorrhea by Wen‐Jing Tang. Furthermore, the antagonistic effect of KCl‐depolarization contractions may be an auxiliary mechanism of the curative effect. Copyright © 2003 John Wiley & Sons, Ltd.
Toxicological analysis and effectiveness of oral Kalanchoe pinnata on a human case of cutaneous leishmaniasis
Authors: Torres‐Santos E. C. , Da Silva S. A. G. , Costa S. S. , Santos A. P. P. T. , Almeida A. P. , Rossi‐Bergmann B.
Published: August 2003

Leishmaniasis is an extremely dif.cult disease to treat. Previously, it was shown that oral Kalanchoe pinnata (Kp) leaf extract is strongly effective against murine leishmaniasis. Here, it is shown that the serum levels of alanine‐aminotransferase (ALT), aspartate‐aminotransferase (AST), urea and alkaline phosphatase were unchanged in mice orally treated with supraoptimal Kp doses for 30 days, indicating the absence of chronic toxicity to the liver, heart or kidney. Additionally, evidence is presented that human leishmaniasis may also be controlled with oral Kp. A 36‐year‐old man with an active cutaneous leishmaniasis was orally treated with 30 g wet weight of Kp leaves/day for 14 days. During the Kp treatment, the lesion stopped growing and slightly decreased. No adverse reactions or toxicity was observed. This study reports for the first time that Kalanchoe pinnata contains substances potentially active and safe for the oral treatment of human cutaneous leishmaniasis. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of antitussive potential of Ionidium suffruticosam Ging. (Violaceae) extract in albino mice
Authors: Boominathan R. , Parimala Devi B. , Mandal Subhash C.
Published: August 2003

The present study was carried out to evaluate the antitussive potential of methanol extract of Ionidium suffruticosam Ging. (Violaceae) which was investigated for its effect on a cough model induced by sulfur dioxide gas in albino mice. It exhibited signi.cant dose‐dependent antitussive activity when compared with the control, 250 and 500 mg/kg (p.o.) of the extract showing 28.37% and 54.16% inhibition of the cough with respect to control group. The antitussive activity of the extract was comparable to that of codeine phosphate, a prototype antitussive agent. Copyright © 2003 John Wiley & Sons, Ltd.
Parallel and Mixture Combined Approach: Rapid Cheap Synthesis and Characterization of a 4096‐Tripeptides Library
Authors: Subra Gilles , Soulère Laurent , Hoffmann Pascal , Enjalbal Christine , Aubagnac Jean‐Louis , Martinez Jean
Published: August 2003

As part of a project that aims to discover novel inhibitors of the enzymes iron‐ superoxide dismutases (FeSODs), a library of 4096 Nter‐acetylated Cter‐amidated tripeptides was designed. To quickly and efficiently synthesize this library without any automation or expensive techniques, an original approach combining “sort and combine” and mixture syntheses was set up. For this purpose, rink amide SynphaseTM Lanterns were chosen as pellicular solid support equipped with colour tagging systems. 512 discrete mixtures of eight tripeptides were prepared with only 64 Synphase D‐Lanterns as starting materials. All the 512 mixtures were analyzed by ESI mass spectrometry Q‐Tof in the positive mode showing that all the 4096 expected members of the library were present in comparable abundances with no trace of side‐products. This paper demonstrates the usefulness of tagged and divisible Synphase lanterns allowing rapid and cheap generation of large organized discrete mixture libraries with high reliability.
Two‐step Multivariate Classification of the Mechanisms of Toxic Action of Phenols
Authors: Ren Shijin
Published: August 2003

A two‐step classification algorithm was developed for the classification and prediction of the mechanisms of toxic action of phenols. The mechanisms considered were polar narcosis, weak acid respiratory uncoupling, pro‐electrophilicity, and soft electrophilicity. The classification algorithm was based on linear discriminant analysis using molecular descriptors as discriminating variables. Polar narcosis/pro‐electrophilicity was separated from weak acid respiratory uncoupling/soft electrophilicity in the first step. In the second step, polar narcosis was separated from pro‐electrophilicity and weak acid respiratory uncoupling was separated from soft electrophilicity. Different molecular descriptors were involved as discriminating variables at different steps of the classification algorithm. This algorithm classified any given phenol as acting by one and only one of the four mechanisms considered. Compared to one‐step classification models, the prediction accuracy of the two‐step algorithm was higher for all four mechanisms involved.
Rheological Properties of Wheat (Halberd) Amylopectin
Authors: Tako Masakuni , Hizukuri Susumu
Published: August 2003

The non‐Newtonian flow behavior and dynamic viscoelasticity of wheat (Halberd) amylopectin in aqueous solution were investigated. The flow curves of Halberd amylopectin at 25 °C showed shear‐thinning behavior at various concentrations (2.0, 4.0 and 6.0%).

The viscosity decreased gradually with increase in temperature at all concentrations investigated. The storage modulus of Halberd amylopectin was rather small and decreased gradually during increase in temperature even in 6.0% solution. The tan δ showed a value of 1.8 at 6.0% even at low temperature (0 °C) and increased slightly with increase in temperature. The storage modulus of Halberd amylopectin (6.0%) increased slightly upon addition of urea (4.0 M) and decreased gradually with increase in temperature. The storage modulus was higher in 0.05 M aqueous NaOH solution (6.0%) than in pure water. However, for tan δ almost the same values were observed in aqueous urea (tan δ = 1.7) and in alkaline (tan δ = 1.6) solution as in pure water (tan δ = 1.8). The storage modulus had a very large value in 85% DMSO. However, the tan δ value in DMSO was almost identical to that in aqueous solution. The results obtained led to the suggestion that in aqueous solution the wheat (Halberd) amylopectin molecules might be involved to a little extent in secondary associations. The structure of wheat (Halberd) amylopectin molecules seems to be different from that of rice amylopectin molecules.
Effects of Growth Temperature on Some Structural Properties of Crystalline Lamellae in Starches Extracted from Sweet Potatoes (Sunnyred and Ayamurasaki)
Authors: Genkina Natalia K. , Noda Takahiro , Koltisheva Galina I. , Wasserman Luybov A. , Tester Richard F , Yuryev Vladimir P.
Published: August 2003

Thermodynamic characteristics defining gelatinisation (modelled as ‘melting’) processes for starches extracted from two sweet potato cultivars (Ayamurasaki and Sunnyred) grown in soil at different temperatures (15, 21, 27 or 33 °C) were studied using high sensitivity differential scanning calorimetry (DSC). The gelatinisation temperatures for all starches were elevated significantly with increasing growth temperature. A linear correlation between growth temperature and gelatinisation temperature of extracted starches was found for both cultivars. The increase of gelatinisation temperatures was associated with almost constant or slightly increased enthalpy (Ayamurasaki) but with moderate elevation of crystalline lamellae thickness (Sunnyred). Elevation of gelatinisation temperatures by 8‐9 °C by DSC for starches heated in 1.5 M aqueous KCl were found in comparison with aqueous starch dispersions. The crystalline polymorphic form was confirmed as A‐type using wide angle X‐ray scattering (WAXS). The values of the thermodynamic surface parameters characterising the faces of crystalline lamellae of these starches were calculated. Two endothermic peaks were observed by DSC for starches grown at 15 °C when suspended in 1.5 M KCl solution. The first peak was ascribed to the melting of B‐type structure while the second one was attributed to the melting of A‐type structure. As a conclusion it was suggested that these starches contain C‐type polymorphic structures.
Molecular and functional characterisation of the zebrafish (Danio rerio) PEPT1‐type peptide transporter1
Authors: Verri Tiziano , Kottra Gabor , Romano Alessandro , Tiso Natascia , Peric Mark , Maffia Michele , Boll Michael , Argenton Francesco , Daniel Hannelore , Storelli Carlo
Published: August 2003

We report the molecular and functional characterisation of a novel peptide transporter from zebrafish, orthologue to mammalian and avian PEPT1. Zebrafish PEPT1 is a low‐affinity/high‐capacity system. However, in contrast to higher vertebrate counterparts in which maximal transport activity is independent of extracellular pH, zebrafish PEPT1 maximal transport rates unexpectedly increase at alkaline extracellular pH. Zebrafish pept1 is highly expressed in the proximal intestine since day 4 post‐fertilisation, thus preceding functional maturation of the gut, first feeding and complete yolk resorption. Zebrafish PEPT1 might help to understand the evolutionary and functional relationships among vertebrate peptide transporters. Moreover, zebrafish pept1 can be a useful marker for screening mutations that affect gut regionalisation, differentiation and morphogenesis.
Global analysis of G‐protein‐coupled receptor signaling in human tissues
Authors: Hakak Yaron , Shrestha Devin , Goegel Moira C. , Behan Dominic P. , Chalmers Derek T.
Published: August 2003

The G‐protein‐coupled receptor (GPCR) family mediates a host of cell–cell communications upon activation by diverse ligands. Numerous GPCRs have been shown to display anatomically selective patterns of gene expression, however, our understanding of the complexity of GPCR signaling within human tissues remains unclear. In an effort to characterize global patterns of GPCR signaling in the human body, microarray analysis was performed on a large panel of tissues to monitor the gene expression levels of the receptors as well as related signaling and regulatory molecules. Analysis of the data revealed complex signaling networks in many tissue types, with tissue‐specific patterns of gene expression observed for the majority of the receptors and a number of components and regulators of GPCR signaling.
Assembly of Tat‐dependent [NiFe] hydrogenases: identification of precursor‐binding accessory proteins
Authors: Dubini Alexandra , Sargent Frank
Published: August 2003

The Escherichia coli twin‐arginine translocation (Tat) system serves to export fully folded protein substrates across the bacterial cytoplasmic membrane. Respiratory [NiFe] hydrogenases are synthesised as precursors with twin‐arginine signal peptides and transported as large, cofactor‐containing, multi‐subunit complexes by the Tat system. Cofactor insertion and assembly of [NiFe] hydrogenases requires coordination of networks of accessory proteins. In this work we utilise a bacterial two‐hybrid assay to demonstrate protein–protein interactions between the uncharacterised chaperones HyaE and HybE with Tat signal peptide‐bearing hydrogenase precursors. It is proposed that the chaperones act at a ‘proofreading’ stage in hydrogenase assembly and police the protein transport pathway preventing premature targeting of Tat‐dependent hydrogenases.
T140 analogs as CXCR4 antagonists identified as anti‐metastatic agents in the treatment of breast cancer
Authors: Tamamura Hirokazu , Hori Akira , Kanzaki Naoyuki , Hiramatsu Kenichi , Mizumoto Makiko , Nakashima Hideki , Yamamoto Naoki , Otaka Akira , Fujii Nobutaka
Published: August 2003

A chemokine receptor, CXCR4, and its endogenous ligand, stromal cell‐derived factor‐1 (SDF‐1), have been recognized to be involved in the metastasis of several types of cancers. T140 analogs are peptidic CXCR4 antagonists composed of 14 amino acid residues that were previously developed as anti‐HIV agents having inhibitory activity against HIV‐entry through its co‐receptor, CXCR4. Herein, we report that these compounds effectively inhibited SDF‐1‐induced migration of human breast cancer cells (MDA‐MB‐231), human leukemia T cells (Sup‐T1) and human umbilical vein endothelial cells at concentrations of 10–100 nM in vitro. Furthermore, slow release administration by subcutaneous injection using an Alzet osmotic pump of a potent and bio‐stable T140 analog, 4F‐benzoyl‐TN14003, gave a partial, but statistically significant (P≤0.05 (t‐test)) reduction in pulmonary metastasis of MDA‐MB‐231 in SCID mice, even though no attempt was made to inhibit other important targets such as CCR7. These results suggest that T140 analogs have potential use for cancer therapy, and that small molecular CXCR4 antagonists could potentially replace neutralizing antibodies as anti‐metastatic agents for breast cancer.
Cartilage injury by ramp compression near the gel diffusion rate
Authors: Morel Véronique , Quinn Thomas M.
Published: August 2003

The mechanics of cartilage injuries have implications for repair strategies. We examined the role of strain rate in cartilage injury under compression near the “gel diffusion” rate (the inherent tissue mechanical relaxation rate). Bovine osteochondral explant disks were subjected to one radially unconfined axial compression at approximately 0.1, 1, 10, 100, or 1000 times the gel diffusion rate to a peak stress of 3.5, 7, or 14 MPa. Effects were monitored in terms of axial strain, changes in water content, superficial cracks, chondrocyte viability, and proteoglycan release. Injury worsened monotonically with peak stress, but varied substantially with strain rate. High strain rates resulted in significant matrix fluid pressurization and impact‐like surface cracking with cell death near the superficial zone. Below the gel diffusion rate, cells died throughout the tissue depth during extensive matrix consolidation without cracks. At approximately the gel diffusion rate, no measurable injury occurred, even for peak stresses of 14 MPa and axial compressive strains near 0.8. The gel diffusion rate therefore represented a threshold separating different biomechanical regimes of injury, but at which cartilage was relatively “safe” from injury. Findings may help identify strategies for prevention and treatment of cartilage injury and suggest loading guidelines for tissue engineering. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Inference of biological and physical parameters in an internal wave using multiple-frequency, acoustic-scattering data
Authors: Warren Joseph D. , Stanton Timothy K. , Wiebe Peter H. , Seim Harvey E.
Published: August 2003

High-frequency sound (>10 kHz) is scattered in the ocean by many different processes. In the water column, marine organisms are often assumed to be the primary source of acoustic backscatter. Recent field experiments and theoretical work suggest that the temperature and salinity microstructure in some oceanic regions could cause acoustic scattering at levels comparable to that caused by marine life. Theoretical acoustic-scattering models predict that the scattering spectra for microstructure and organisms are distinguishable from each other over certain frequency ranges. A method that uses multiple-frequency acoustic data to exploit these differences has been developed, making it possible to discriminate between biological and physical sources of scattering under some conditions. This method has been applied to data collected in an internal wave in the Gulf of Maine. For regions of the internal wave in which the dominant source of scattering is either biological or physical in origin, it is possible to combine the acoustic-scattering data and temperature and salinity profiles with acoustic-scattering models to perform a least-squares inversion. Using this approach, it is possible to estimate the dissipation rate of turbulent kinetic energy for some regions of the internal wave, and the length and numerical abundance of the dominant biological scatterer, euphausiids, in others.
Generation of unmagnetized motion of plasma sheet electrons and its possible causes
Authors: Antonova E. E. , Stepanova M. V. , Vikhreva E. A. , Ovchinnikov I. L. , Teltzov M. V.
Published: August 2003

Results of experimental and theoretical studies of unmagnetized stochastic motion of the plasma sheet electrons and the mixing of plasma in the plasma sheet are presented. Analysis of the electron temperature distributions within the plasma sheet is undertaken using the data from Intercosmos‐Bulgaria‐1300 polar orbiting satellite. The electron temperature is obtained with consideration of acceleration of precipitating electrons by the field‐aligned potential drop; this temperature is nearly constant in the meridional direction and has no longitudinal dependence during quiet geomagnetic conditions. Analysis of spacial fluctuations of precipitating electron fluxes for a fixed electron energy shows that fluctuation spectra of primary electrons have a power dependence and resemble the spectra of electric field fluctuations observed within the plasma sheet. The satellite observations are interpreted in terms of stochastic motion of the plasma sheet electrons and intensive mixing of plasma in the sheet. It is suggested that the electron motion in the electric field with a characteristic scale comparable with the electron Larmor radius is a source of stochastization; chaotization of the particle trajectories could be a part of stochastization process. The particle motion in a homogeneous magnetic field and in a regular inhomogeneous electric field with a sinusoidal distribution in one direction and a homogeneous distribution in the perpendicular direction is analyzed as an example of the chaotic motion.
Latitudinally dependent Trimpi effects: Modeling and observations
Authors: Clilverd Mark A. , Yeo Richard F. , Nunn David , Smith Andy J.
Published: August 2003

Modeling studies show that the exclusion of the propagating VLF wave from the ionospheric region results in the decline of Trimpi magnitude with patch altitude. In large models such as Long Wave Propagation Capability (LWPC) this exclusion does not occur inherently in the code, and high‐altitude precipitation modeling can produce results that are not consistent with observations from ground‐based experiments. The introduction to LWPC of realistic wave attenuation of the height gain functions in the ionosphere solves these computational problems. This work presents the first modeling of (Born) Trimpi scattering at long ranges, taking into account global inhomogeneities and continuous mode conversion along all paths, by employing the full conductivity perturbation matrix. The application of the more realistic height gain functions allows the prediction of decreasing Trimpi activity with increasing latitude, primarily through the mechanism of excluding the VLF wave from regions of high conductivity and scattering efficiency. Ground‐based observations from Faraday and Rothera, Antarctica, in September and October 1995 of Trimpi occurring on the NPM (Hawaii) path provide data that are consistent with these predictions. Latitudinal variations in Trimpi occurrence near L = 2.5, with a significant decrease of about 70% occurrence between L = 2.4 and L = 2.8, have been observed at higher L shell resolution than in previous studies (i.e., 2 < L < 3).
The terrestrial potassium layer (75–110 km) between 71°S and 54°N: Observations and modeling
Authors: Eska V. , von Zahn U. , Plane J. M. C.
Published: August 2003

Observations of the nighttime atmospheric potassium layer were performed on the German research vessel Polarstern from March to June 1996. K density profiles were obtained between 71°S and 45°N. The nightly mean peak densities ranged from 140 cm−3 in the equatorial region to 10 cm−3 in the Antarctic, and the column abundances decreased from 1.2 × 108 to 1.3 × 107 cm−2 going from low to high latitudes. High peak densities and column abundances were also commonly observed together with sporadic K layers. The global mean peak height of the normal (background) K layer was found to be 88.3 km. After the Polarstern campaign, observations were continued at Kühlungsborn (54°N). The summer and winter K layers, observed during July 1996 and January 1997, were quite different in shape but had similar peak densities and column abundances. A one‐dimensional model of the K layer was developed which includes meteoric deposition, vertical transport through eddy diffusion, and a full chemical scheme. This model was able to reproduce very satisfactorily the seasonal behavior of the K layer at 54°N if the wintertime deposition flux of the metal was reduced by 30% compared to the summer. The midlatitude ratio of K to Na was about 1%, much less than either the chondritic or cosmic ratios of the two metals (≈8 or 6%, respectively). The most likely reason is that potassium vaporizes less efficiently from meteoroids than sodium, in agreement with a thermodynamic model of a nonideal chondritic magma and observations in the exosphere of Mercury. Finally, the model was generally very successful in reproducing the latitudinal variations in the K layer.
Magnetospheric line radiation observations at Halley, Antarctica
Authors: Rodger Craig J. , Clilverd Mark A. , Yearby Keith H. , Smith Andy J.
Published: August 2003

Magnetospheric line Radiation (MLR) events are relatively narrowband VLF signals that sometimes drift in frequency, and have been observed in both ground based and satellite data sets. Line radiation has been attributed by some authors to be power line harmonic radiation (PLHR), generated from harmonics of the power transmission frequency (50 or 60 Hz) and radiated into the ionosphere and magnetosphere by long power lines. We present the result of a survey undertaken on the basis of measurements made of MLR events observed at Halley station, Antarctica (75°30′S, 26°54′W, L ≈ 4.3) in part of June 1995. Particular attention is given to the frequency spacing, drift rates, and amplitude of the MLR lines. MLR is present in 7.0% of the minute‐long VLF recordings made at Halley. The MLR lines rise in frequency as often as they fall. However, these lines do not necessarily rise or fall monotonically and can oscillate while drifting. The Halley MLR has a wide range of line spacings and does not preferentially show spacings near harmonics of electrical transmission frequencies, either 50 Hz or 60 Hz. There is no correlation between the frequency drifts of the local 50 Hz Halley electrical supply and those of the observed MLR lines. The distribution of MLR line spacings observed in the Halley data has a roughly exponential form, suggesting a different mechanism for MLR than for PLHR.
Direct determination of IMF BY‐related cusp current systems, using SuperDARN radar and multiple ground magnetometer data: A link to theory on cusp current origin
Authors: Amm O. , Engebretson M. J. , Greenwald R. A. , Lühr H. , Moretto T.
Published: August 2003

We analyze an ionospheric “enhanced convection event” in the cusp on November 13, 1996, at 1900 UT, by using data of the SuperDARN radar, and of the IMAGE, Greenland, MACCS and CANOPUS magnetometer arrays; and from other magnetometer stations. The event occurs ∼20 minutes after a transition of the IMF BY component from positive to negative and an associated reconfiguration of the ionospheric electric potential pattern. The data allow an instantaneous two‐dimensional view of the event in terms of the ionospheric electric and ground magnetic field. The “method of characteristics” is used to obtain distributions of ionospheric conductances, actual ionospheric currents, and field‐aligned currents (FACs) for the interval under study. Our results show that the region of enhanced convection observed by the radar is associated with a region of low conductances, ranging only slightly above the UV conductance values. However, owing to the strongly enhanced electric field, it produces enhanced westward flowing Hall and southward flowing Pedersen currents. At the northern and southern borders of the enhanced convection region, sheets of downward and upward FACs are observed, respectively, with magnitudes of around 0.5 A/km2. The geometry of the current system resembles a DPY current system [Friis‐Christensen and Wilhjelm, 1975]. Using our results, we test alternative theories on cusp current origin that lead to different predictions of the relative location of the cusp current system with respect to the open‐closed field line boundary. The location of this boundary is inferred from DMSP F10 satellite data. The center of our resulting current system is located clearly poleward of the open‐closed field line boundary, thus favoring the idea of Lee et al. [1985] that the cusp FACs are caused by a rotational discontinuity of the magnetic field at the magnetopause. In contrast, the idea of Clauer and Banks [1986] that a mapping of the solar wind Ez component to the ionosphere is responsible for the cusp current system is not supported.
Time‐limited excitation of damped field‐line resonances: Implications for satellite observations
Authors: McDiarmid D. R. , Wright A. N. , Allan W.
Published: August 2003

It is common to think of resonance width in steady state terms, but there are two important factors which make this approach inappropriate for field‐line resonance (FLR) pulsations in the magnetosphere. First of all, the excitation is short‐lived, i.e., decidedly not monochromatic. Second, for excitations of interest, FLR widths diminish with time [Mann et al., 1995], and the ionospheric damping of these resonances in concert with their short‐lived excitation ensures that they are time‐limited. The widths most likely to be observed are those corresponding to a time near that of the maximum amplitude of the pulsation. As a consequence, observed FLR widths are greater, sometimes significantly greater, than the steady state equivalent (i.e., the Q width). Each FLR oscillation is the sum of two components; one is an oscillation at the resonant frequency, and the other, which is the transient portion of the response, is at the natural resonant frequency of each flux tube. The latter frequency varies with L. Moreover, as the excitation becomes more short‐lived, the shorter is the duration of the FLR in a lossy magnetosphere/ionosphere, and the greater the influence of the transient. The purpose of this paper is to examine the possibility that a random or quasi‐random ensemble of short‐lived excitations of the magnetospheric waveguide over the Pc3 – 5 range might yield FLR widths sufficiently large in practice for the pulsation signature to be similar to that seen in Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE) satellite pulsation data. The latter signature appears to be consistent with each flux tube ringing at several of its natural resonance harmonics. It is found that under some realistic conditions the ensemble of excitations can produce FLR spectral widths which are contiguous or overlap in L, suggesting the possibility of an FLR explanation of AMPTE/CCE pulsation observations.
Resonant acceleration and heating of solar wind ions by dispersive ion cyclotron waves
Authors: Hu You Qiu , Habbal Shadia Rifai
Published: August 2003

We investigate the preferential acceleration and heating of solar wind alpha particles by the resonant cyclotron interaction with parallel‐propagating left‐hand‐polarized ion cyclotron waves. The Alfvén wave spectrum equation is generalized to multi‐ion plasmas and a Kolmogorov type of cascade effect is introduced to transfer energy from the low‐frequency Alfvén waves to the high‐frequency ion cyclotron waves, which are assumed to be entirely dissipated by the wave‐particle interaction. In order to distribute the dissipated wave energy among the alphas and protons, the quasi‐linear theory of the wave‐particle interaction is used along with the cold plasma dispersion relation, and a power law spectrum of the ion cyclotron waves is assumed, with the spectral index as a free parameter of the model. The set of three‐fluid solar wind equations and the Alfvén wave spectrum equation are then solved in order to find fast solar wind solutions. It is found that the effect of the alpha particles on the dispersion relation, omitted in most previous wave‐driven solar wind models, has a significant influence on the preferential acceleration and heating of the alphas, especially in the region close to the Sun. With this effect included, the alpha particles can be accelerated to a bulk flow speed faster than the protons by a few hundred kilometers per second and heated by the resonant cyclotron interaction to more than mass‐proportional temperature values at several solar radii. However, this mechanism does not yield a differential speed of the order of an Alfvén speed and a mass‐proportional temperature for the alphas beyond 0.3 AU, as observed, which confirms the same conclusion reached previously by Isenberg and Hollweg [1983] for nondispersive ion cyclotron waves.
Latitudinal dynamics of auroral roar emissions
Authors: Shepherd S. G. , LaBelle J. , Carlson C. W. , Rostoker G.
Published: August 2003

Auroral roar, a narrowband (δƒ/ƒ < 0.1) emission near 2 and 3 times the ionospheric electron gyrofrequency (2ƒce and 3ƒce), is observed with a meridional chain of LF/MF/HF radio receivers located in northern Canada spanning 67° to 79° invariant latitude. Observations of these emissions are compared with the auroral electrojet location inferred from the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) magnetometer array. Variations in the intensity of the observed auroral roar emissions and in the invariant latitude of the most intense emissions are correlated with movements of the poleward boundary of the electrojet. For example, substorm onsets, which appear as rapid poleward expansions of this boundary, result in screening of the emissions from the underlying ground stations because of precipitation‐induced ionization in the lower ionosphere. In four of the five study days the peak emission intensity is located 0°–9° poleward of the poleward electrojet boundary inferred from the magnetometers. In one case the peak emission intensity is up to 10° equatorward of the poleward electrojet boundary. In all cases, there is a tendency for the latitude of the most intense auroral roar emissions to track the movements of the electrojet location inferred from the magnetometer data. For two examples, the footprint of the Fast Auroral Snapshot (FAST) satellite passes within 3° of one or more of the ground stations, and the satellite detects unstable electron populations in the polewardmost auroral arc, reinforcing the scenario that auroral roar emissions are generated by these electrons in the polewardmost arc and propagate into the polar cap where conditions are often favorable for their detection at ground level.
Geomagnetic response at low latitude to continuous solar wind pressure variations during northward interplanetary magnetic field
Authors: Francia P. , Lepidi S. , Villante U. , Di Giuseppe P. , Lazarus A. J.
Published: August 2003

A study of the geomagnetic field response to a series of continuous solar wind pressure variations has been performed at a low‐latitude station during interplanetary events characterized by stable northward magnetic field conditions. The geomagnetic field H component responds well to the solar wind pressure changes on a timescale of few minutes. The amplitude of the geomagnetic field response is found to depend on local time, showing greater values around local noon and midnight.
Excitation of short‐scale field‐aligned electron density irregularities by ionospheric topside sounders
Authors: Kuo S. P. , Lee M. C. , Kossey Paul
Published: August 2003

Generation of short‐scale field‐aligned electron density irregularities on a short timescale (≪ 1 s) by ionospheric topside sounder pulses is studied. It is a four‐wave parametric coupling process, in which a sounder‐launched Z mode pump wave decays into two electron Bernstein sidebands and a geomagnetic field‐aligned density irregularity. The dispersion relation of the parametric coupling process has been derived and analyzed. The results show that meter‐scale field‐aligned electron density irregularities (FAI) can be excited with growth rates of the order of 105 s−1 under the resonance conditions that ƒ0≅ƒp≅nƒc where ƒ0, ƒp, and ƒc are the pump wave frequency, electron plasma frequency, and electron cyclotron frequency, respectively, and n is an integer. The excited FAI extend along the magnetic field toward the satellite path, causing the incoherent scattering of the subsequently transmitted sounding pulses. This is suggested to be a possible cause of long‐duration Z mode echoes appearing on the Alouette 2 ionograms when ƒ0≅ƒp≅nƒc, as reported by Benson [1997]. It is found that the threshold field of the instability decreases with increased n. It may explain why long‐duration Z mode echoes were only observed when n ≥ 4.