bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of inducible nitric oxide generation by agmatine aldehyde: Beneficial effects in sepsis
Authors: Satriano Joseph , Schwartz Doron , Ishizuka Shunji , Lortie Mark J. , Thomson Scott C. , Gabbai Francis , Kelly Carolyn J. , Blantz Roland C.
Published: August 2002

The induction of inducible nitric oxide synthase (iNOS) serves an important immuno‐protective function in inflammatory states, but ungoverned nitric oxide (NO) generation can contribute to a number of pathologic consequences. Delineation of the mechanisms that can downregulate iNOS‐generated NO in inflammation could have therapeutic relevance. Here we show that agmatine, a metabolite of arginine, inhibits iNOS mediated nitric oxide generation in cytokine stimulated cell culture preparations. This effect was not cell type specific. Increased diamine oxidase (DAO) and decreased aldehyde dehydrogenase (AldDH) activities are also representative of inflammatory settings. Increasing the conversion of agmatine to an aldehyde form by addition of purified DAO or suppression of aldehyde breakdown by inhibition of AldDH activity increases the inhibitory effects of agmatine in an additive fashion. Inhibitors of DAO, but not monoamine oxidase (MAO), decreased the inhibitory effects of agmatine, as did the addition of AldDH or reacting aldehydes with phenylhydrazine. We examined rats given lipopolysaccharide (LPS) to evaluate the potential effects of agmatine in vivo. Endotoxic rats administered agmatine prevented the decreases in blood pressure and renal function normally associated with sepsis. Agmatine treatment also increased the survival of LPS treated mice. Our data demonstrate the capacity of agmatine aldehyde to suppress iNOS mediated NO generation, and indicate a protective function of agmatine in a model of endotoxic shock. How agmatine may aid in coordinating the early NO phase and the later repair phase responses in models of inflammation is discussed. © 2001 Wiley‐Liss, Inc.
Endothelial exposure to hypoxia induces Egr‐1 expression involving PKCα‐mediated Ras/Raf‐1/ERK1/2 pathway
Authors: Lo Leu‐Wei , Cheng Jing‐Jy , Chiu Jeng‐Jiann , Wung Being‐Sun , Liu Yu‐Chi , Wang Danny Ling
Published: August 2002

Hypoxia induces endothelial dysfunction that results in a series of cardiovascular injuries. Early growth response‐1 (Egr‐1) has been indicated as a common theme in vascular injury. Here we demonstrates that in bovine aortic endothelial cells (ECs) subjected to hypoxia (PO2 ≈ 23 mmHg), rapidly increased Egr‐1 mRNA expression which peaked within 30 min and decreased afterwards. Treatment of ECs with PD98059, a specific inhibitor to mitogen‐activated protein kinase (MAPK/ERK), inhibited this hypoxia‐induced Egr‐1 expression. The involvement of ERK pathway was further substantiated by the inhibition of Egr‐1 promoter activities when ECs were co‐transfected with a dominant negative mutant of Ras (RasN17), Raf‐1 (Raf 301), or a catalytically inactive mutant of ERK2 (mERK). In addition, the hypoxia‐induced transcriptional activity of Elk‐1, an ERK substrate, was abolished by administration of PD98059. Addition of calphostin C, a protein kinase C (PKC) inhibitor, completely blocked the hypoxia‐augmented Egr‐1 expression. The likewise occurred while exposing ECs to D609 to inhibit phospholipase C and BAPTA/AM to chelate intracellular calcium. Hypoxia to ECs increased ERK phosphorylation within 10 min and which was abolished by administration of PD98095, calphostin C, and BAPTA/AM. Hypoxia triggered a transient translocation of PKCα from cytosol to membrane fraction concurrent with the association of PKCα to Raf‐1. Involvement of PKCα in mediating ERK activation was further confirmed by the inhibition of ERK and the subsequent Egr‐1 gene induction with antisense oligonucleotides to PKCα. These results indicate that ECs under hypoxia induce Egr‐1 expression and this induction requires calcium, phospholipase C activation, and PKCα‐mediated Ras/Raf‐1/ERK1/2 signaling pathway. Our finding support the importance of specific PKC isozyme linked to MAPK pathway in the regulation of endothelial responses to hypoxia. © 2001 Wiley‐Liss, Inc.
Intrarenal arteriovenous fistula causing a ‘‘pseudonutcracker effect’’
Authors: Yagmurlu Banu , Özcan Hasan , Aytaç Suat Kemal , Bilgiç Sadık , Sanlıdilek Umman
Published: August 2002

We report a case in which an intrarenal arteriovenous fistula caused the nutcracker effect. Color Doppler sonography of the left renal artery showed a peak systolic velocity of 150 cm/second and renoaortic ratio of 2.1. The left renal vein was significantly dilated, and the adjacent renal artery was kinked. A stenosis in the left renal vein at the aorto‐ mesenteric bifurcation was demonstrated, with a maximum velocity of 201 cm/second. Renal Doppler evaluation showed an area of high‐velocity, low‐resistance arterial flow consistent with an arteriovenous fistula in the inferior half of the left kidney. Angiography confirmed the fistula. The fistula was successfully occluded by coil embolization. Follow‐up sonography showed almost complete obliteration of the fistula, regression of the renal vein dilatation, and a reduction in renal venous and arterial flow velocities. Given the reversibility of the fistula's effects, we suggest the term ‘‘pseudonutcracker effect’’ to describe this case. © 2002 John Wiley & Sons, Inc. J Clin Ultrasound 30:109–113, 2002; DOI 10.1002/jcu.10030
Sonographic findings in glomus tympanicum tumor
Authors: De Candia Alessandro , Como Giuseppe , Passon Paolo , Pedace Ernesto , Bazzocchi Massimo
Published: August 2002

A glomus tympanicum tumor that is associated with a visible retrotympanic mass is the most frequent cause of pulsatile tinnitus. The preoperative diagnostic approach to this lesion includes a meticulous physical examination as well as high‐resolution CT, magnetic resonance angiography, and digital angiography, which can also be used for preoperative embolization. We report the use of color transcranial Doppler sonography in the evaluation of glomus tympanicum tumor in a 67‐year‐old woman with a 3‐year history of left tinnitus. An otoscopic examination revealed a reddish pulsatile mass behind an intact tympanic membrane. No lesions were visualized on gray‐scale sonography. Contrast‐enhanced color transcranial Doppler sonography showed a vascular ovoid mass that measured 2 × 1 × 1 cm; spectral analysis of the lesion revealed arterial flow with a low resistance index. Color transcranial Doppler sonography helped define the dimensions and vascular characteristics of the lesion. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30:236–240, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10058
Comparative anatomy of the podocyte: A scanning electron microscopic study
Authors: Takahashi‐Iwanaga Hiromi
Published: August 2002

The three‐dimensional structure of the renal glomerular podocyte was comparatively analyzed with special reference to its cellular interdigitation. Kidneys of lampreys, carps, eels, xenopuses, bullfrogs, iguanas, rats, and rabbits were used as materials. Urinary and basal surfaces of podocytes were exposed by a conventional freeze‐fracture method and by NaOH maceration, respectively, and subsequently examined by scanning electron microscopy. In accordance with previous reports, each podocyte consisted of a round cell body protruding into Bowman's space, four to six major processes embracing glomerular capillary, and numerous pedicels on both sides of the major processes. The podocyte pedicels exhibited uniform needle‐like shapes, about 0.2 μm thick, interdigitated with those of adjoining cells along the entire length of the cell margins in all the animal species examined. This finding suggests that the fine pedicel interdigitation is a primary event in morphogenesis of the podocyte. The basal aspect of the glomerular epithelium was mosaicked with pedicels which were laid at various angles to the capillary axis, in favor of its possible role as a mechanical support of the capillary wall. Microsc. Res. Tech. 57:196–202, 2002. © 2002 Wiley‐Liss, Inc.
Re‐evaluation of nestin as a marker of oligodendrocyte lineage cells
Authors: Almazán Guillermina , Vela José Miguel , Molina‐Holgado Eduardo , Guaza Carmen
Published: August 2002

Maturation of oligodendrocyte progenitors (O2A) is characterized by morphological changes and the sequential expression of specific antigens leading to the formation of myelin membrane. Monoclonal antibodies A2B5, A007, anti‐vimentin, and anti‐galactocerebroside, recognize oligodendroglia at different stages of development. The neuroepithelial precursor marker nestin is also expressed by the oligodendroglial lineage; we have used enriched populations of progenitors isolated from neonatal rat brain cultures to further examine the cellular distribution of this intermediate filament protein. The phenotypic distribution of nestin positive cells among the oligodendrocyte lineage showed that 65% reacted with A2B5, whereas only 5% were A007+, and 4% galactocerebroside+. The remaining 25% of the cells were not labeled and had small cellular bodies devoid of processes, characteristic of the pre‐O2A progenitor. Further analysis of the nestin+ population showed that the majority of the cells were also vimentin+. Antibody‐dependent complement mediated cytolysis of A2B5+ (O2A cells) and galactocerebroside+ (mature oligodendrocytes) cells left a population of nestin+ cells that were induced to proliferate in the presence of growth factors and to differentiate into A2B5+ and galactocerebroside+ cells. Proliferating cells maintained in the presence of platelet‐derived growth factor or basic fibroblast growth factor retained nestin expression along with A2B5. By contrast, in serum‐free medium nestin expression decreased while postmitotic cells acquired A007 and galactocerebroside. Our results suggest that nestin expression is a marker of pre‐O2A cells that is maintained in proliferating glial progenitors, but is quickly down‐regulated in postmitotic oligodendrocytes (A007+/galacto‐cerebroside+) along with A2B5 and vimentin. However, other glial cells including type 2 astrocytes and some amoeboid microglia also share nestin expression. Microsc. Res. Tech. 52:753–765, 2001. © 2001 Wiley‐Liss, Inc.
Circadian organization and the role of the pineal in birds
Authors: Underwood Herbert , Steele Christopher T. , Zivkovic Bora
Published: August 2002

All organisms exhibit significant daily rhythms in a myriad of functions from molecular levels to the level of the whole organism. Significantly, most of these rhythms will persist under constant conditions, showing that they are driven by an internal circadian clock. In birds the circadian system is composed of several interacting sites, each of which may contain a circadian clock. These sites include the pineal organ, the suprachiasmatic nucleus (SCN) of the hypothalamus, and, in some species, the eyes. Light is the most powerful entraining stimulus for circadian rhythms and, in birds, light can affect the system via three different pathways: the eyes, the pineal, and extraretinal photoreceptors located in the deep brain. Circadian pacemakers in the pineal and in the eyes of some avian species communicate with the hypothalamic pacemakers via the rhythmic synthesis and release of the hormone melatonin. Often the hypothalamic pacemakers are unable to sustain persistent rhythmicity in constant conditions in the absence of periodic melatonin input from the pineal (or eyes). It has also been proposed that pineal pacemakers may be unable to sustain rhythmicity in constant conditions without periodic neural input from the SCN. Significant variation can occur among birds in the relative roles that the pineal, the SCN, and the eyes play within the circadian system; for example, in the house sparrow pacemakers in the pineal play the predominant role, in the pigeon circadian pacemakers in both the pineal and eyes play a significant role, and in Japanese quail ocular pacemakers play the predominant role. Microsc. Res. Tech. 53:48–62, 2001. © 2001 Wiley‐Liss, Inc.
Catecholaminergic and acetylcholine esterase containing nerves of cranial and spinal dura mater in humans and rodents
Authors: Artico Marco , Cavallotti Carlo
Published: August 2002

The innervation of cranial and spinal dura mater in humans and rodents was studied by examining several dural zones (vascular, perivascular, intervascular) in different regions. Characterization and distribution of dural acetylcholinesterase‐positive nerve fibers, catecholaminergic nerve fibers, and mast cells are analyzed and discussed. The results of chemical and surgical sympathectomy as well as the relationships between catecholaminergic nerve fibers and mast cells are studied. Our results are discussed in the light of possible implications in the physiopathology of dural algic syndromes including cephalalgia and spinal pain. Microsc. Res. Tech. 53:212–220, 2001. © 2001 Wiley‐Liss, Inc.
Effects of age and GDNF on noradrenergic innervation of the hippocampal formation: Studies from intraocular grafts
Authors: Granholm A.‐C. , Helt C. , Srivastava N. , Backman C. , Gerhardt G.A.
Published: August 2002

Recent studies have suggested that factors in the target tissue influence the degree of plasticity and regeneration following aging and/or specific insults. We have investigated whether young or aged targets differ in their noradrenergic innervation from fetal locus coeruleus (LC) neurons, and also if a specific growth factor, glial cell line‐derived neurotrophic factor (GDNF) can affect this innervation pattern. Tissue pieces of fetal brainstem and young (3 months) or old (18 months) iris tissue were transplanted simultaneously into the anterior chamber of the eye of adult hosts. We found that aged iris transplants became innervated to a significantly lesser degree by the cografted LC neurons than young iris transplants. Fetal hippocampal tissue was then grafted to adult hosts, and a fetal brainstem graft containing LC neurons was placed adjacent to the first graft, either at 3 or 21 months post‐grafting. Thus, old/young chimeras of the noradrenergic coeruleo‐hippocampal pathway were created. Aged hippocampal grafts received a much less dense innervation from co‐grafted LC neurons than young hippocampal grafts. Tyrosine hydroxylase‐positive‐immunoreactive innervation was only found in the outskirts of aged grafts, while the young hippocampal grafts contained an even innervation pattern. The innervation density of hippocampal grafts was significantly enhanced by GDNF treatment. These findings demonstrate that target‐derived factors may regulate neuronal plasticity, and that the age of the target is more important for innervation properties than the age of the neuron innervating a particular target. Microsc. Res. Tech. 54:298–308, 2001. © 2001 Wiley‐Liss, Inc.
Deduced primary structure of vitellogenin in the giant freshwater prawn, Macrobrachium rosenbergii, and yolk processing during ovarian maturation
Authors: Okuno Atsuro , Yang Wei‐Jun , Jayasankar Vidya , Saido‐Sakanaka Hisako , Huong Do Thi Thanh , Jasmani Safiah , Atmomarsono Muharijadi , Subramoniam Thanumalayaperumal , Tsutsui Naoaki , Ohira Tsuyoshi , Kawazoe Ichiro , Aida Katsumi , Wilder Marcy N.
Published: August 2002

A cDNA encoding vitellogenin (Vg) in the giant freshwater prawn, Macrobrachium rosenbergii, was cloned based on the cDNA sequence of vitellin (Vn) fragments A‐N and B‐42 determined previously, and its amino acid sequence deduced. The open reading frame (ORF) encoded 2,537 amino acid residues and its deduced amino acid sequence possessed three consensus cleavage sites, R‐X‐R‐R, similar to those reported in Vgs of insects. The deduced primary structure of Vg in M. rosenbergii was seen to be similar to that of Penaeus japonicus, especially in the N‐terminal region. It is therefore likely that Vgs in crustacean species including prawns and other related decapods exhibit a similar structural pattern. Based on the deduced primary structure of Vg and analysis of the various Vg and Vn subunits found in the hemolymph and ovary during ovarian maturation, we demonstrated the post‐translational processing of Vg in M. rosenbergii. This is the first time that Vg processing has been clearly demonstrated in a crustacean species. Vg, after being synthesized in the hepatopancreas, is considered to be cleaved by a subtilisin‐like endoprotease to form two subunits, A and proB, which are then released into the hemolymph. In the hemolymph, proB is possibly cleaved by a processing enzyme of unknown identity to give rise to subunits B and C/D. The three processed subunits A, B, and C/D are sequestered by the ovary to give rise to three yolk proteins, Macr‐VnA, VnB, and VnC/D. J. Exp. Zool. 292:417–429, 2002. © 2002 Wiley‐Liss, Inc.
Macro‐evolution of the hairy enhancer in Drosophila species
Authors: Kim Junhyong
Published: August 2002

It has been suggested that many of the changes in the developmental program might be in the cis‐acting promoters and enhancer regions. Here I study the macro‐evolutionary changes of an enhancer region for the early developmental gene hairy in Drosophila melanogaster, D. simulans, D. pseudoobscura, D. willistoni, D. nebulosa, D. hydei, and D. virilis. The enhancer region is characterized by small, highly conserved blocks interspersed among highly variable regions. Nevertheless, species phylogenies constructed by the enhancer sequences agree with the widely accepted phylogeny of these species. The evolution of the variable regions is consistent with a molecular clock, while the evolution of the conserved blocks is significantly different from a clock. In particular, the D. pseudoobscura lineage shows the highest degree of species‐specific change consistent with changes in expression timing reported in an earlier study. It has been suggested that the variation in sequence length between highly conserved blocks may play a role in the coordination of regulatory processes, such as protein–protein interactions; thus, stabilizing selection has been suggested to act on the length variations. Here I develop a test for stabilizing selection on length variation and show that the hairy enhancer does not show statistically significant evidence for stabilizing selection. J. Exp. Zool. (Mol. Dev. Evol.) 291:175–185, 2001. © 2001 Wiley‐Liss, Inc.
The tetrapod limb: A hypothesis on its origin
Authors: Wagner Günter P. , Chiu Chi‐Hua
Published: August 2002

A wrist joint and structures typical of the hand, such as digits, however, are absent in [Eustenopteron] (Andrews and Westoll, ’68, p 240).

Great changes must have been undergone during evolution of the ankle joint; the small number of large bones in the fin must somehow have developed into a large number of small bones, and it is very difficult to draw homologies in this region, or even be certain of what is being compared (Andrews and Westoll, ’68, p 268).

The tetrapod limb is one of the major morphological adaptations that facilitated the transition from an aquatic to a terrestrial lifestyle in vertebrate evolution. We review the paleontological evidence for the fin‐limb transition and conclude that the innovation associated with evolution of the tetrapod limb is the zeugopodial‐mesopodial transition, i.e., the evolution of the developmental mechanism that differentiates the distal parts of the limb (the autopodium, i.e., hand or foot) from the proximal parts. Based on a review of tetrapod limb and fish fin development, we propose a genetic hypothesis for the origin of the autopodium. In tetrapods the genes Hoxa‐11 and Hoxa‐13 have locally exclusive expression domains along the proximal‐distal axis of the limb bud. The junction between the distal limit of Hoxa‐11 expression and of the proximal limit of Hoxa‐13 expression is involved in establishing the border between the zeugopodial and autopodial anlagen. In zebrafish, the expression domains of these genes are overlapping and there is no evidence for an autopodial equivalent in the fin skeleton. We propose that the evolution of the derived expression patterns of Hoxa‐11 and Hoxa‐13 may be causally involved in the origin of the tetrapod limb. J. Exp. Zool. (Mol. Dev. Evol.) 291:226–240, 2001. © 2001 Wiley‐Liss, Inc.
Codiameters of 3‐connected 3‐domination critical graphs
Authors: Chen Yaojun , Tian Feng , Wei Bing
Published: August 2002

A graph G is 3‐domination critical if its domination number γ is 3 and the addition of any edge decreases γ by 1. Let G be a 3‐connected 3‐domination critical graph of order n. In this paper, we show that there is a path of length at least n−2 between any two distinct vertices in G and the lower bound is sharp. © 2002 John Wiley & Sons, Inc. J Graph Theory 39: 76–85, 2002
Managing multinationals: the governance of investment for the environment
Authors: Newell Peter
Published: August 2002

This paper explores the possibilities and limitations of different approaches to the regulation of transnational corporations in a context of globalization. Looking at environmental initiatives in particular, the paper considers the pros and cons of emerging public and private strategies for promoting corporate responsibility from a development perspective. The role of ‘civil regulation’, litigation against companies, and international legal instruments are assessed in this light. It is argued that each of these approaches, while not necessarily complementary, has a role to play in promoting positive investment strategies and deterring irresponsible investment practices in developing countries. Copyright © 2001 John Wiley & Sons, Ltd.
Wired for change: the links between ICTs and development discourses
Authors: Schech Susanne
Published: August 2002

The ICT revolution's promises and threats for developing countries can be brought into clearer perspective if we pay attention to the underlying discourses on development and knowledge employed in this debate. This paper suggests that those who enthusiastically embrace ICTs tend to operate within a modernization discourse, while sceptics are influenced by dependency and post‐colonial discourses of development. Both perspectives operate with a liberal notion of knowledge as separate from power. The paper argues that a more fruitful approach is to analyse the role ICTs play in the power–knowledge nexus. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of ring‐14C‐labelled 4(3′‐, 6′‐dimethyl‐3′‐heptyl)‐phenol
Authors: Lalah J. O. , Lenoir D. , Henkelmann B. , Hertkorn N. , Günther K. , Schramm K.‐W. , Kettrup A.
Published: August 2002

Ring‐14C‐labelled 4(3′‐, 6′‐, dimethyl‐3′‐,heptyl)‐phenol (NP), an isomer of paranonyl phenol was synthesized for use in aquatic toxicity and metabolism studies. A very efficient method involving alkylation of ring‐14C‐labelled anisole and tertiary alkyl bromide (3‐bromo‐3,6‐dimethyl heptane) with AlCl3 followed by cleavage of the resultant ether with BBr3 was used giving a 24% yield ring labelled 14C‐NP (specific activity: 16.205 MBq/mg and purity >95% by HPLC) after TLC separation. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of N‐(2‐chloro‐5‐methylthiophenyl)‐ N′‐(3‐methyl‐thiophenyl)‐ N′‐[3H3]methylguanidine, {[3H3]CNS‐5161}
Authors: Gibbs Andrew R. , Morimoto Hiromi , VanBrocklin Henry F. , Williams Philip G. , Biegon Anat
Published: August 2002

The preparation of the title compound, [3H3]CNS‐5161, was accomplished in three steps starting with the production of [3H3]iodomethane (CT3I). The intermediate N‐[3H3]methyl‐3‐(thiomethylphenyl)cyanamide was prepared in 77% yield by the addition of CT3I to 3‐(thiomethylphenyl)cyanamide, previously treated with sodium hydride. Reaction of this tritiated intermediate with 2‐chloro‐5‐thiomethylaniline hydrochloride formed the guanidine compound [3H3]CNS‐5161. Purification by HPLC gave the desired labeled product in an overall yield of 9% with >96% radiochemical purity and a final specific activity of 66 Ci mmol−1. Copyright © 2002 John Wiley & Sons, Ltd.
Evidence for a DNA triplex in a recombination‐like motif: I. Recognition of Watson–Crick base pairs by natural bases in a high‐stability triplex
Authors: Walter Axel , Schütz Holger , Simon Hannelore , Birch‐Hirschfeld Eckhard
Published: August 2002

Data are presented on a triplex type with two parallel homologous strands for which triplex formation is almost as strong as duplex formation at least for some sequences and even at pH 7 and 0.2 MNaCl. The evidence mainly rests upon comparing thermodynamic properties of similar systems. A paperclip oligonucleotide d(A12C4T12C4A12) with two linkers C4obviously can form a triplex with parallel back‐folded adenine strand regions, because the single melting transition of this complex splits in two transitions by introducing mismatches only in the third strand region. Respectively, a hairpin duplex d(A12C4T12) and a single strand d(A12) form a triplex as a 1:1 complex in which the second adenine strand is parallel oriented to the homologous one in the Watson–Crick paired duplex. In this system the melting temperatureTmof the triplex is practically the same as that of the duplex d(A12)·d(T12), at least within a complex concentration range of 0.2–4.0 µM. The melting behaviour of complexes between triplex stabilizing ligand BePI and the system hairpin duplex plus single strand supports the triplex model. Non‐denaturing gel electrophoresis suggests the existence of a triplex for a system in which five of the twelve A·T*A base triads are substituted by C·G*C base triads.  The recognition between any substituted Watson–Crick base pair (X·Y) in the hairpin duplex d(A4XA7C4T7YT4) and the correspondingly replaced base (Z) in the third strand d(A4ZA7) is mutually selective. All triplexes with matching base substitutions (Z = X) have nearly the same stability (Tmvalues from 29 to 33.5°C), whereas triplexes with non‐matching substitutions (Z ≠ X) show a clearly reduced stability (Tmvalues from 15 to 22°C) at 2µMequimolar oligonucleotide concentration. Most nucleic acid triple helices hitherto known are limited to homopurine–homopyrimidine sequences in the target duplex. A stable triplex formation is demonstrated for inhomogeneous sequences tolerating at least 50% pyrimidine content in the homologous strands. On the basis of the surprisingly similar thermodynamic parameters for duplex and triplex, and of the fact that this triplex type seems to be more stable than many other natural DNA triplexes known, and on the basis of semiempirical and molecule mechanical calculations, we postulate bridging interactions of the third strand with the two other strands in the triplex according to the recombination motif. This triplex, denoted by us ‘recombination‐like form’, tolerates heterogeneous base sequences. Copyright © 2001 John Wiley & Sons, Ltd.

Abbreviations used:

CD

circular dichroism

DF

degrees of freedom

TFO

triplex‐forming oligonucleotide.
Elusive recognition determinants for ubiquitination
Authors: Banerjee Amit , Wade Rebecca C.
Published: August 2002

How are proteins recognized as substrates for ubiquitination? Here we summarize insights from recent experiments that address this issue. These highlight the diversity and complexity of determinants for substrate recognition, and raise many questions for further investigation. Copyright © 2002 John Wiley & Sons, Ltd.
Assessment of tumor oxygenation in human cervical carcinoma by use of dynamic Gd‐DTPA‐enhanced MR imaging
Authors: Lyng Heidi , Vorren Ann O. , Sundfør Kolbein , Taksdal Ingeborg , Lien Hans H. , Kaalhus Olav , Rofstad Einar K.
Published: August 2002

Increased knowledge of the physiological basis behind the signal enhancement in tumors during dynamic contrast‐enhanced magnetic resonance (MR) imaging may be useful in development of predictive assays based on this technique. In the present work, the relative signal intensity (RSI) increase in gadopentetate dimeglumine (Gd‐DTPA)‐enhanced MR images of patients with cervical carcinoma was related to tumor perfusion, vascular density, cell density, and oxygen tension (pO2). The patients were subjected to MR imaging before the start of treatment (N = 12) and after two weeks of radiotherapy (N = 8). Perfusion was determined from the kinetics of contrast agent in tumors and arteries, vascular density and cell density were determined from tumor biopsies, and pO2 was determined by polarographic needle electrodes. The maximal RSI was correlated to perfusion (P = 0.002) and cell density (P = 0.004), but was not related to vascular density. There was also a correlation between pO2 and perfusion (P < 0.001). Moreover, pO2 tended to be correlated to cell density (P = 0.1), but was not related to vascular density. There was a significant correlation between RSI and pO2, regardless of whether the median pO2 (P < 0.001) or the fraction of pO2 readings below 2.5 mmHg (P < 0.001), 5 mmHg (P < 0.0001), or 10 mmHg (P < 0.001) was considered. Our results suggest that the Gd‐DTPA‐induced signal enhancement in MR images of cervical tumors is influenced by both perfusion and cell density. These parameters are also of major importance for tumor oxygenation, leading to a correlation between signal enhancement and oxygenation. Dynamic contrast‐enhanced MR imaging may therefore possibly be useful in prediction of treatment outcome. J. Magn. Reson. Imaging 2001;14:750–756. © 2001 Wiley‐Liss, Inc.
Comparison of two volumetric techniques for estimating liver volume using magnetic resonance imaging
Authors: Mazonakis Michael , Damilakis John , Maris Thomas , Prassopoulos Panos , Gourtsoyiannis Nicholas
Published: August 2002

Purpose

To compare the conventional technique of manual planimetry with the point counting technique for estimating liver volume from magnetic resonance imaging (MRI) data.

Materials and Methods

This study comprised abdominal MR examinations of 38 consecutive patients. Evaluation of the images showed that liver size appeared normal in 27 patients and increased in 11. Liver volume was estimated using the techniques of planimetry and point counting. Both techniques were used in combination with the Cavalieri method of modern design stereology. A systematic slice sampling procedure was performed to estimate liver volumes using both volumetric techniques. The point counting technique was optimized by altering the point spacing of the grid. The agreement between the two techniques was found. Measurement repeatability of both volumetric techniques was also evaluated.

Results

Both techniques allowed the same degree of optimization through the procedure of systematic section sampling. The application of a point spacing of 2.5 cm reduced the time measurement by a factor of 3.5 in relation with the time needed with planimetry. An excellent agreement was observed between the two volumetric techniques with mean differences (±SD) of 2.4 ± 41.6 cm3 and 8.5 ± 49.8 cm3 for the patients presenting normal and increased liver sizes, respectively. Both techniques were highly reproducible.

Conclusion

The point counting technique could be considered a more efficient approach than planimetry for estimating liver volume from MRI, due to its speed and simplicity. J. Magn. Reson. Imaging 2002;15:557–563. © 2002 Wiley‐Liss, Inc.
Fetal shoulder measurements by fast and ultrafast MRI techniques
Authors: Tukeva Timo A. , Salmi Hanna , Poutanen Veli‐Pekka , Karjalainen Pertti T. , Hytinantti Timo , Paavonen Jorma , Teramo Kari A. , Aronen Hannu J.
Published: August 2002

The purpose of this study was to evaluate magnetic resonance imaging (MRI) of fetal shoulder measurements of fetuses with suspected macrosomia. The actual fetal shoulder measurements made immediately after birth were compared with measurements obtained by fast and ultrafast MRI techniques antepartum. Eight singleton diabetic pregnant mothers underwent MRI examination with fast imaging in steady‐state precession (TrueFISP) and spin‐echo (SE) and gradient‐echo (GE) echo‐planar (EPI) sequences to show the fetal shoulder width. The actual shoulder width was measured immediately postpartum by a neonatologist. There was a statistically significant correlation between the MRI measurements and the actual shoulder width (P < 0.001 – P < 0.05) for all sequences. TrueFISP (r = 0.98, P < 0.001) was superior to EPI sequences (r = 0.88, P < 0.01 for SE EPI and r = 0.80, P < 0.05 for GE EPI). The images of all three sequences used were free of major motion artifacts. Fast and ultrafast sequences seem to be reliable for fetal shoulder measurements and the TrueFISP was the most accurate sequence compared to SE and GE echo‐planar sequences. J. Magn. Reson. Imaging 2001;13:938–942. © 2001 Wiley‐Liss, Inc.
Magnetic resonance imaging of atherosclerotic plaques using superparamagnetic iron oxide particles
Authors: Schmitz Stephan A. , Taupitz Matthias , Wagner Susanne , Wolf Karl‐Jürgen , Beyersdorff Dirk , Hamm Bernd
Published: August 2002

Experimental data show accumulation of superparamagnetic iron oxide (SPIO) particles in atherosclerotic plaques. SPIO uptake occurred in plaques, suggesting an increased endothelial permeability and macrophage infiltrates as signs of inflammatory plaque activity. We incidentally observed SPIO uptake in aortic and arterial wall segments in patients who had originally received the magnetic resonance (MR) contrast agent for staging lymph node metastases. Twenty patients (19 male, 1 female; mean age, 64; range, 41–78 years) with bladder or prostate cancer underwent MR imaging (MRI) using a T2*‐weighted high‐resolution gradient‐echo sequence prior to and 24–36 hours after intravenous injection of 2.6 mg of Fe/kg of SPIO (Sinerem®). The aorta, both common external and internal iliac, as well as both superficial femoral arteries, were retrospectively analyzed for atherosclerotic wall changes. One patient was excluded. A positive finding was defined as an area of pronounced signal loss on postcontrast images clearly confined to the arterial wall, which was absent in the precontrast examination or increased in size. Such a finding was observed in one to three arteries in 7 of the 19 patients. The pronounced signal loss in the wall of the aorta and pelvic arteries seen in part of an elderly patient population after intravenous SPIO administration strongly suggests that this contrast agent accumulates in human atherosclerotic plaques. J. Magn. Reson. Imaging 2001;14:355–361. © 2001 Wiley‐Liss, Inc.
Transvascular and interstitial transport of a 19 kDa linear molecule in human melanoma xenografts measured by contrast‐enhanced magnetic resonance imaging
Authors: Bjørnæs Ingvil , Rofstad Einar K.
Published: August 2002

Cancer therapy involving blood‐borne macromolecular therapeutic agents often fails, owing to inadequate macromolecule uptake in malignant tissue. The transvascular and interstitial transport of a 19 kDa linear molecule (NC22181 or poly‐[Gd‐DTPA]‐co‐[1,6‐diaminohexane]) was studied in the present work in an attempt to identify transport barriers limiting the delivery of macromolecules to tumors. Tumors of four human melanoma xenograft lines were included in the study. The uptake of NC22181 was measured by spoiled gradient recalled magnetic resonance imaging (MRI). The effective microvascular permeability constant and the interstitial influx constant of NC22181 were calculated from NC22181 uptake curves by using a three‐compartment tissue model. The uptake of NC22181 was limited by the interstitial transport and not by thetransvascular transport in all xenograft lines. If the melanoma xenografts used in this study are representative models of human cancer, our results suggest that strategies for increasing the delivery of macromolecular therapeutic agents to tumors should focus on improving the transport conditions in the interstitium, rather than enhancing the permeability of the microvascular wall. J. Magn. Reson. Imaging 2001;14:608–616. © 2001 Wiley‐Liss, Inc.
Minimizing analyte electrolysis in an electrospray emitter
Authors: Kertesz Vilmos , Van Berkel Gary J.
Published: August 2002

The electrospray (ES) ion source is a controlled‐current electrolytic flow cell. Electrolytic reactions in the ES emitter capillary are continually ongoing to sustain the production of charged droplets and ultimately gas‐phase ions from this device. Under certain circumstances, the analytes under study may be directly involved in these electrolytic processes. It is demonstrated that a simple means to minimize analyte electrolysis is to exchange the normal metal emitter capillary of commercial ES sources with one made of fused silica. This change is shown to provide an ES mass spectrometric system of similar performance in terms of gas‐phase ion signal generated for non‐electroactive analytes and also assures minimal oxidation of electroactive analytes even at low (2.0 µl min−1) solution flow‐rates and high (millimolar) solution electrolyte concentrations. Published in 2001 by John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization Fourier transform mass spectrometric analysis of oxygenated triglycerides and phosphatidylcholines in egg tempera paint dosimeters used for environmental monitoring of museum display conditions
Authors: van den Brink Oscar F. , Boon Jaap J. , O'Connor Peter B. , Duursma Marc C. , Heeren Ron M. A.
Published: August 2002

Oxidative changes in triacylglycerols and diacylphosphatidylcholines in egg tempera paint strips are used for chemical dosimetry of the quality of the museum environment. High‐resolution matrix‐assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI‐FTMS) was used as a rapid method for the determination of the exact elemental composition of the alteration products from diacylphosphatidylcholines and triacylglycerols. Light exposure of the egg tempera paints yields oxygenated diacylphosphatidylcholines and triacylglycerols. In the latter multiple incorporation of oxygen was observed as a recurring mass difference of 15.995, the exact atomic mass of oxygen. Owing to the high resolution of the FTMS data (routinely 20 000 at m/z 1000 in broadband mode), oxidation products with different elemental compositions but identical nominal mass could be distinguished. Products of oxidative cleavage of triacylglycerols were observed in samples exposed for longer times. The relative intensities of the peaks of singly and multiply oxygenated triacylglycerols were used to derive the degree of oxygenation of the egg lipids in the tempera paint dosimeters. The degree of oxygenation was found to be directly related to the light exposure time. Exposure to elevated temperature (60 °C) for a period of 21 days did not lead to oxygenation of the triacylglycerols and diacylphosphatidylcholines. Exposure to NOx and SO2 in the dark greatly increased the degree of oxygenation. Addition of lead‐ or copper‐containing pigments to the egg binding medium (and subsequent storage for 6 months in the dark) led to accelerated conversion of egg lipids to oxidised products. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization and differentiation of ruthenium(II) complexes with 1,4,7‐trithiacyclononane and nitrogen heterocycles by electrospray mass spectrometry
Authors: Santana‐Marques M. Graça O. , Amado Francisco M. L. , Correia A. J. Ferrer , Lucena Mónica , Madureira João , Goodfellow Brian J. , Félix Vítor , Santos Teresa M.
Published: August 2002

Electrospray ionization mass spectrometry (ESIMS) was used to characterize a series of new ruthenium(II) complexes with several nitrogen heterocycles and a common ligand: the crown thioether 1,4,7‐trithiacyclononane, [9]aneS3. ESIMS allows the easy identification of the [RuIICl([9]aneS3)Y]X complexes, where Y is a bidentate nitrogen heterocycle and X is Cl− or PF6−, through the formation of two diagnostic ions by fragmentation of the common ligand [9]aneS3. Structures for these ions and mechanisms for their gas‐phase formation are proposed based on data from product ion spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of RSD921 in human plasma by high‐performance liquid chromatography–tandem mass spectrometry using tri‐deuterated RSD921 as internal standard: application to a phase I clinical trial
Authors: Ribeiro Wellington , Ifa Demian R , Corso Gaetano , Salmon John , Moraes Leonardo A. , Eberlin Marcos N. , Nucci Gilberto de
Published: August 2002

A fast, sensitive and specific method is presented for the quantification of RSD921 in human plasma by liquid chromatography coupled with tandem mass spectrometry using tri‐deuterated RSD921 (3d‐RSD921) as an internal standard. A single‐step liquid/liquid extraction was performed with diethyl ether/hexane (80 : 20, v/v) using 0.5 ml of plasma. The plasma calibration curves were linear from 0.1 to 20 ng ml−1 (r > 0.999). Between‐run precision, based on the percent relative deviation for replicate (n = 40) quality controls, was ≤7.27% (0.5 ng ml−1), ≤7.39% (5.0 ng ml−1), and ≤5.06% (20.0 ng ml−1). Between‐run accuracies, based on the relative error, were ±2.59%, ±1.23% and ±1.64% respectively. The method was developed to evaluate the pharmacokinetic profile after 15 min of intravenous stepwise‐ascending infusion dose of RSD921 in 18 healthy volunteers. A dissociation study of protonated RSD921 and 3d‐RSD921 by collision‐induced dissociation using in‐source fragmentation and tandem mass spectrometry is also presented. Copyright © 2001 John Wiley & Sons, Ltd.
Integration of mass spectrometry into early‐phase discovery and development of central nervous system agents
Authors: Prokai Laszlo , Zharikova Alevtina , Janáky Tamás , Li Xiaoxu , Braddy April C. , Perjési Pál , Matveeva Lidia , Powell David H. , Prokai‐Tatrai Katalin
Published: August 2002

The early‐phase discovery and development of useful central nervous system (CNS) agents present ample opportunities to exploit mass spectrometry and provide detailed compound/mixture characterization, or to make the process faster and/or more economic. Neuropeptide FF antagonists and centrally active thyrotropin‐releasing hormone analogues were used as specific examples in this work. We evaluated the characterization of focused libraries of peptide derivatives by electrospray ionization, tandem mass spectrometry and liquid chromatography/tandem mass spectrometry on a quadrupole ion trap and nanoelectrospray on a Fourier transform ion cyclotron resonance mass spectrometer. Immobilized artificial‐membrane chromatography was employed as a model to predict/rank new agents against lead compounds for their potential to reach the central nervous system in pharmacologically significant amounts. Measuring brain concentrations in rodents after the intravenous administration of test compounds was used as an in vivo approach, and we took advantage of microdialysis sampling that furnished samples without interfering tissue matrix and afforded the estimation of extracellular concentrations in a localized part of the brain. Overall, making atmospheric‐pressure ionization mass spectrometry an integral part of the process has played a major role in increasing throughput, selectivity, specificity and detection sensitivity and thereby providing useful information about the extent or mechanism of transport and metabolic activation/inactivation in early‐phase discovery and development of CNS agents. Copyright © 2001 John Wiley & Sons, Ltd.
Fragmentation study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, using post‐source decay matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Kéki Sándor , Deák György , Zsuga Miklós
Published: August 2002

A post‐source decay matrix‐assisted laser desorption/ionization mass spectrometric (PSD‐MALDI‐MS) study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, is reported. The fragmentations of rutin were performed by selecting the [R + Cat]+ peaks for PSD, where R represents a rutin molecule and Cat an alkali metal ion (Li+, Na+, K+). The PSD‐MALDI mass spectra showed, depending on Cat, different fragmentation patterns with respect to both the quality and quantity of the fragment ions formed. The intensity of fragmentation decreased in the order Li+ > Na+ > K+. The fragmentation mechanism and an explanation for the observed differences are suggested. Copyright © 2001 John Wiley & Sons, Ltd.
Resonant electron capture mass spectrometry of free fatty acids: examination of ion structures using deuterium‐labeled fatty acids and collisional activation
Authors: Voinov Valery G. , Van den Heuvel Hilde , Claeys Magda
Published: August 2002

The structures of [M–H]− ions generated from free fatty acids in resonant electron capture at energies of 1.2 and 7.2 eV were investigated using deuterium‐labeled isotopomers and collision‐induced dissociation. The [M–H]−· ions occur in both a carboxylate anion and a carbanion form. While the formation of the carboxylate anion at 1.2 eV involves the loss of a carboxylic hydrogen, that at 7.2 eV involves the loss of a hydrogen from different positions in the aliphatic chain followed by a rearrangement of a carboxylic hydrogen on to the radical site in the chain. The [M–H–H2O]− ion which is a minor ion in the resonant electron capture spectrum at 7.2 eV is shown to be a precursor for the charge‐remote fragment ions corresponding to formal losses of a hydrogen and elements of alkanes. The [M–H–H2O]− ion corresponding to the second major ion in the resonant electron capture spectrum at 7.2 eV is demonstrated to be consistent with a cyclopentanone anion structure. On the basis of new insights obtained in the present study and taking into account previous results, an updated proposal is presented for the mechanism of charge‐remote fragmentation which operates in resonant electron capture of free fatty acids at 7.2 eV. Copyright © 2002 John Wiley & Sons, Ltd.
9‐Nitrocamptothecin inhibits HIV‐1 replication in human peripheral blood lymphocytes: A potential alternative for HIV‐infection/AIDS therapy
Authors: Hung Chia‐Ling , Doniger Jay , Palini Alessio , Snyder Stuart W. , Radonovich Michael F. , Brady John N. , Pantazis Panayotis , Sadaie M. Reza
Published: August 2002

The ability of the anti‐cancer drug, 9‐Nitrocamptothecin (9NC), to inhibit replication of HIV‐1 in clinically relevant primary lymphocytic cells was studied. Primary peripheral blood lymphocytes (PBLs) from a non‐infected donor were freshly infected with HIV‐1 and treated with 9NC by using three different treatment schedules. Cells were monitored for cytotoxicity by the XTT metabolic cell proliferation assay and a sensitive flow cytometric assay that was capable of measuring cell cycle changes and apoptosis. 9NC inhibited replication of HIV‐1 in PBLs by greater than 95% in a dose‐dependent manner as measured by the level of extracellular HIV‐1 p24 release. Similar results were observed, whether 9NC was applied in a single, double, or triple dose regimen. Minimal cytotoxicity was observed for both non‐infected and infected PBLs, as determined by the XTT assay. Moreover, 9NC induced apoptosis within 24 hours of drug treatment in freshly infected, but not non‐infected, PBLs. The data showed that 9NC reduced replication of HIV‐1 in primary human lymphocytes; thus, it indicates the potential clinical utility of this drug as an alternative or adjunct therapy for HIV‐infection/AIDS. J. Med. Virol. 64:238–244, 2001. © 2001 Wiley‐Liss, Inc.