bluuebunny/crossref_metadata_2025 huggingface dataset:
A new and simple synthesis of N‐succinimidyl‐4‐[127/125I]iodobenzoate involving a microwave ‐ accelerated iodination step
Authors: Khalaj Ali , Beiki Davood , Rafiee Hamid , Najafi Reza
Published: August 2002

A short and simple method for the preparation of N‐succinimidyl‐4‐iodobenzoate 3 and its 125I analogue that is widely used for radioiodination of proteins is described. The method involves the reaction of in situ generated trimethylsilyl iodide [127I or 125I] from trimethylsilyl chloride with N‐succinimidyl‐4‐[3,3‐(1,4‐butanediyl)‐triazene] benzoate 2 available from the condensation of N‐hydroxysuccinimide and 1‐(4‐carboxyphenyl)‐3,3‐(1,4‐butanediyl)‐triazene 1 in the presence of dicyclohexyl carbodiimide (DCC). The new triazene 1 was prepared by precipitating the diazonium ion of 4‐aminobenzoic acid with pyrrolidine. A microwave‐mediated rate acceleration was observed during the iodination step and by applying this procedure the labelled compound 3 was obtained in 81% radiochemical yield in 8 minutes. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of 2,6‐dideoxy‐2‐fluoro‐6‐[18F]‐fluoro‐β‐D‐glucopyranosyl fluoride (2,6FGF) as a potential imaging probe for glucocerebrosidase
Authors: Wong Alexander W. , Adam Michael J. , Withers Stephen G.
Published: August 2002

We have previously synthesized 2‐deoxy‐2‐[18F]‐fluoro‐β‐mannosyl [18F]‐fluoride and shown that it behaves as a mechanism‐based inhibitor of Agrobacterium sp. β‐glucosidase. In‐vivo experiments indicate that this compound undergoes partial hydrolysis to produce 2‐deoxy‐2‐fluoro‐mannose, which can become phosphorylated and trapped within the cell. We now report the synthesis of another 2‐fluoro glycoside which is 18F‐labelled at the 6 position so that the label cannot be lost during such glycoside hydrolysis and which, further, cannot be phosphorylated. The mechanism‐based glycosidase inhibitor 2,6‐dideoxy‐2‐fluoro‐6‐[18F]‐fluoro‐β‐D‐glucopyranosyl fluoride (2,6FGF) was synthesized in 69% overall chemical yield and in 9% radiochemical yield (decay corrected) as a potential imaging probe for glycosidase. Copyright © 2001 John Wiley & Sons, Ltd.
Radiochemical synthesis and preliminary evaluation of anti‐bladder cancer monoclonal antibody BDI‐1 labeled with rhenium‐188
Authors: Wang Rongfu , Zhang Chungli , Yu Lizhang , Guo Yifeng , Bai Ying
Published: August 2002

The anti‐human bladder cancer monoclonal antibody BDI‐1 was radio‐labeled with rhenium‐188 by direct labeling methods using SnCl2 as reductant and MDP as stannous stabilizer or by indirect method using NHS‐ECM ester as bifunctional chelator. Radiochemical yields of 30±7.23% and 87.4±5.67% and radiochemical purity of more than 95% were achieved. The inmmunoreactive fraction was 58.7%. The results showed that radionuclide 188Re might be employed using the same labeling methodology with 99mTc labeling of BDI‐1 for radiommunoimaging (RII) and radioimmunotherapy (RIT) and that may be useful in radioimmunodetection and RIT of human bladder carcinoma in vivo. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and preliminary evaluation of a carbon‐11‐labelled agonist of the α7 nicotinic acetylcholine receptor
Authors: Dolle Frédéric , Valette Héric , Hinnen Françoise , Vaufrey Françoise , Demphel Stéphane , Coulon Christine , Ottaviani Michéle , Bottlaender Michel , Crouzel Christian
Published: August 2002

The lead compound of a new series of azabicyclic carbamates described by Astra Laboratories as ligands for the α7 nicotinic acetylcholine receptor subtype, namely N‐(4‐bromophenyl)carbamic acid quinuclidin‐3‐yl ester, has been labelled with carbon‐11 using no‐carrier‐added [11C]phosgene and the isocyanate pathway. Typically, 25–35 mCi (0.92–1.29 GBq) of the tracer was obtained within 30 min of radiosynthesis (HPLC purification included) with specific radioactivities ranging from 500 to 800 mCi/µmol (18.5–29.6 GBq/µmol). Biodistribution studies demonstrated a relatively good brain uptake of the compound (0.8–1.2% I.D./g tissue in various brain regions), but without preferential concentration in brain regions rich in α7‐subtype nicotinic receptor (e.g. hippocampus, pons and colliculi). No specific binding could be demonstrated in pre‐saturation studies performed with both the cold compound and nicotine. Therefore, this ligand is not suitable for further exploration in PET imaging. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of 123I labeled Congo Red via solid phase organic chemistry
Authors: Kabalka George W. , Namboodiri Vasudevan , Akula Murthy R.
Published: August 2002

A polymer supported synthesis of 123I labeled Congo Red has been developed that provides a high yield of radiochemically pure product. Copyright © 2001 John Wiley & Sons, Ltd.
The deuteriation of constituents in olive oil and red wine with Nafion, a polymer supported acid catalyst
Authors: Tuck Kellie L. , Hayball Peter J.
Published: August 2002

A procedure for the deuteriation of a large range of aromatic compounds with phenolic and methoxy substituents has been developed using Nafion, a polymer supported acid catalyst. A range of compounds present in red wine and olive oil were deuteriated using these conditions. This procedure provides a facile route for the labelling of homovanillic alcohol, homovanillic acid, syringic acid, syringaldehyde and vanillin. This method is also applicable for the tritiation of these compounds. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and characterization of 4,6‐dichloroindole‐based radioligands for imaging the glycine site of the NMDA ion channel
Authors: Waterhouse R. N. , Sultana A. , Guo N. , Lee Bora , Simpson N. , Collier Lee , Laruelle M.
Published: August 2002

To provide effective PET or SPECT ligands for the glycine binding site of the NMDA ion channel, we have synthesized and characterized in vitro four substituted derivatives of the potent glycine site antagonist 3‐[2‐[(phenylamino)carbonyl]ethenyl]‐4,6‐dichloroindole‐2‐carboxylic acid (Ki=3.0 nM). These new ligands contain groups amenable to labeling with C‐11 for PET, or I‐123 for SPECT. In vitro analysis of these compounds revealed that placement of a methoxy group at either the ortho or para position of the phenylaminocarbonyl group significantly reduced receptor affinity (Ki=74.0±8.1 and 26.5±4.9 nM, respectively), as did placement of an iodine at the para position (Ki=60.4±8.2 nM). However, the meta‐methoxy derivative (4b) maintained high affinity (Ki=4.8±0.9 nM) for the glycine site and was therefore labeled with carbon‐11 by reacting the corresponding desmethyl derivative with [11C]methyl iodide. Radiochemical yields of 14±10% (EOS), and high specific activity (1.2±0.5 Ci/μmol (EOS, n=7)) were realized, and the product was prepared in a sterile saline solution suitable for in vivo use. Copyright © 2002 John Wiley & Sons, Ltd.
A convenient synthesis of [11C]paraquat and other [N‐methyl‐11C]bisquaternary ammonium compounds
Authors: Jewett Douglas M. , Kilbourn Michael R.
Published: August 2002

[11C]Paraquat was synthesized by the reaction of [11C]methyl triflate with the mono‐triflate salt of 1‐methyl‐[4,4′]bipyridinyl. The product was selectively separated from the precursor by a microcolumn of Chelex 100 ion exchange resin. The method was applied to the synthesis of a variety of [N‐methyl‐11C]bisquaternary ammonium compounds. This is the first reported use of a chelating cation exchange resin for the selective purification of organic dications. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis, radiolabelling and biological evaluation of terminal oxamide derivatives of mercaptoacetyltriglycine
Authors: Okarvi S.M. , Torfs P. , Adriaens P. , Verbruggen A.M.
Published: August 2002

99mTc‐MAG3 is widely used in clinical nuclear medicine as a potential replacement of 131I‐OIH for renal function studies. The terminal carbonylglycine in the MAG3 backbone is assumed to be essential for maintaining its efficient renal handling characteristics. A number of MAG3‐derivatives have been prepared and evaluated in which the terminal carbonylglycine sequence is substituted by an oxamide moiety in order to study the effect of the modified carbonylglycine sequence on the renal handling characteristics. These ‘oxamide’ derivatives have been synthesized starting from mercaptoacetic acid or cysteamine using the common synthetic procedures of peptide chemistry. These thiol‐protected MAG3‐precursors were labelled with 99mTc by an exchange method using tartrate as a complexing agent. Biodistribution studies in mice showed that some of these agents were cleared rapidly from the blood and efficiently excreted into the urine and displayed comparable renal excretion characteristics to those of 99mTc‐MAG3. Copyright © 2002 John Wiley & Sons, Ltd.
Neurotransmitters regulating acid secretion in the proventriculus of the Houbara bustard (Chlamydotis undulata): A morphological viewpoint
Authors: Mensah‐Brown E.P.K. , Lawrence P.A.
Published: August 2002

Endocrine cells containing somatostatin (Som), gastrin‐releasing peptide (GRP), and neuronal nitric oxide synthase (nNOS) and nerve fibers containing choline acetyl transferase (ChAT), tyrosine hydroxylase (TH), galanin (Gal), substance P (SP), and vasoactive intestinal polypeptide (VIP) were immunolocalized in the proventriculus of the Houbara bustard, Chlamydotis undulata. While GRP‐immunoreactive (GRP‐IR) cells occur in the inner zone, somatostatin (Som‐IR) and polyclonal nNOS (nNOS‐IR) immunoreactive cells were localized mainly in the peripheral zone of submucosal glands. GRP‐IR, Som‐IR, and nNOS‐IR cells were occasionally observed in the walls of the gastric glands. Endocrine cells are of the closed variety and usually possess apical processes extending along the basal surfaces of adjacent nonreactive cells. Ultrastructural features of these cells are typical. ChAT, Gal, SP, VIP, and TH were immunolocalized in nerve fibers and terminals in the walls of arterioles and capillaries at the periphery of submucosal glands. Immunoreactivity to monoclonal nNOS occurred mainly in neuronal cell bodies in ganglia located around the submucosal glands. ChAT and TH immunoreactive cell bodies were also occasionally seen around the submucosal glands in the peripheral region. Immunoreactivity to Gal, SP, and VIP, but not ChAT or TH, was discernible around the walls of gastric glands. It was concluded that the distribution of neurotransmitters in neuronal structures is similar, but that of the endocrine cells varies from that of some avian species. The roles of these neurotransmitters in the regulation of acid secretion are discussed. J. Morphol. 248:175–184, 2001. © 2001 Wiley‐Liss, Inc.
Ultrastructural aspects of the development of the hyaline layer and extracellular matrix lining the gastrointestinal tract in embryos and larvae of the starfish Pisaster ochraceus preserved by freeze substitution
Authors: Pang T. , Crawford B.J. , Campbell S.S.
Published: August 2002

Embryos and larvae of the starfish Pisaster ochraceus are surrounded by a complex extracellular matrix (ECM) layer called the hyaline layer (HL). A similar but less well‐organized ECM layer lines some regions of the larval gut. Examination of material preserved by freeze substitution shows that the HL consists of a coarse outer meshwork, a boundary layer, a supporting layer, which is divided into three sublayers, H1, H2, and H3, and an intervillus layer. The development of the HL has been studied in material preserved by freeze substitution. Development begins at fertilization when exocytosis of the cortical granules releases ECM into the perivitelline space and elevates the fertilization membrane. Shortly after, plaques of dense material with attached fibers are present on the outer surface of the egg plasmalemma. Following this, these plaques and fibers are associated with the tips of short microvilli, suggesting that they may induce microvillus formation. Next, the tips of some of the microvilli are joined by short regions of the H1 sublayer. Some of these H1 regions have short segments of boundary layer material associated with their outer surfaces while others are naked. Just prior to hatching, the H1 and boundary layers completely surround the embryo, separating the developing coarse meshwork and intervillus layers. Short segments of the H2 and H3 sublayers are also present. Posthatching, the microvilli and all HL layers increase in thickness and density, particularly the H2, boundary, and coarse outer meshwork layers. The results suggest a sequential organization of HL components from ECM that is secreted into the perivitelline space. J. Morphol. 251:169–181, 2002. © 2002 Wiley‐Liss, Inc.
Fine structural and cytochemical observations of dental epithelial cells during the enameloid formation stages in red stingrays Dasyatis akajei
Authors: Sasagawa Ichiro
Published: August 2002

The fine structure and the localization of nonspecific acid phosphatase (ACPase), nonspecific alkaline phosphatase (ALPase), and calcium‐dependent adenosine triphosphatase (Ca‐ATPase) activities in the dental epithelial cells in tooth germs of Dasyatis akajei in the later stages of enameloid formation were investigated. Numerous invaginations of the distal cell membrane of the inner dental epithelial (IDE) cells were observed at the early stage of enameloid maturation. The invaginations contain many fine granular and filamentous substances; the lamina densa, which was thicker during the former stages, is obscure. Granules exhibiting defined ACPase activity were usually found in the IDE cells during the stages of enameloid mineralization and maturation. IDE cells are putatively involved in the removal of degenerated enameloid matrix during these stages. Marked ALPase activity was detected at the proximal and the lateral cell membranes of the IDE cells from the late stage of enameloid matrix formation to the early stage of enameloid maturation. Strong activity of Ca‐ATPase was localized at the proximal and the lateral cell membranes of the IDE cells during the stages of enameloid mineralization and maturation. ALPase and Ca‐ATPase activity is probably related to crystal formation in the enameloid and the removal of degenerated enameloid matrix from the enameloid. J. Morphol. 252:170–182, 2002. © 2002 Wiley‐Liss, Inc.
Functional characterization of an anti‐estradiol antibody by site‐directed mutagenesis and molecular modelling: modulation of binding properties and prominent role of the VL domain in estradiol recognition
Authors: Coulon Stéphane , Pellequer Jean‐Luc , Blachère Thierry , Chartier Martine , Mappus Elisabeth , Chen Shu‐wen W. , Cuilleron Claude Yves , Baty Daniel
Published: August 2002

The high‐affinity monoclonal anti‐estradiol antibody 9D3 presents a specificity defect towards estradiol‐3‐sulphate and 3‐glucuronide conjugates incompatible with use in direct immunoassays. The corresponding single‐chain variable fragment (scFv), cloned and produced in E. coli, exhibited a 10‐fold lower affinity for estradiol (Ka = 1.2 × 109 M
−1) and a slightly increased specificity defect for the 3‐position. Site‐directed mutagenesis revealed critical residues involved in estradiol recognition and produced mutants exhibiting up to a 3‐fold increase of the binding affinity for estradiol and up to a 2‐fold decrease of the cross‐reactivity with estradiol‐3‐sulphate. A comparative model of the antibody 9D3‐estradiol complex was built in which the estradiol D‐ring is buried into the binding pocket while the 3‐, 6‐ and 7‐positions are solvent exposed, agreeing with the lack of specificity for these three positions. Two potential alternative orientations of the A‐ring, one close to CDR H3 and L2 loops, and the other one close to CDR H2 and L3 loops, have been considered for the docking of estradiol, none of which could be unambiguously privileged taking into account data from cross‐reactivity measurements, photolabelling and mutagenesis studies. For both orientations, estradiol is stabilized by hydrogen bonding of the 17β‐OH group with TyrL36, His89 and GlnH35 in the first case, or TyrL36, only, in the second case and by van der Waals contacts from TyrL91 with α‐ or β‐face of estradiol, respectively, and from ValH95 and GlyH97 with the opposite face. To elucidate the molecular basis of antibody 9D3 specificity, as compared with that of another anti‐estradiol antibody 15H11, single variable domains (VH and VL) and scFv hybrids have been constructed. The binding activity of VL9D3 as well as the specificity of the VL9D3/VH15H11 hybrid, both similar to antibody 9D3, revealed a prominent role of VL in estradiol recognition. These findings establish premises for antibody engineering to reduce cross‐reactivity, especially with estradiol‐3‐conjugates. Copyright © 2002 John Wiley & Sons, Ltd.
Arterial first pass gadolinium‐CM dynamics as a function of several intravenous saline flush and Gd volumes
Authors: Boos Matthias , Scheffler Klaus , Haselhorst R. , Reese Eva , Fröhlich J. , Bongartz Georg M.
Published: August 2002

This study was performed to evaluate the dynamics of an arterial first pass gadolinium (Gd) contrast medium (CM) bolus at the descending aorta (DAo), depending on various saline flush and Gd volumes. Using an ultra‐fast two‐ dimensional GE‐sequence (Siemens Vision®, 1.5‐T), 200 sequential cross‐sectional images of the addressed vessel (1 slice/s) were obtained. Several saline flush volumes (15 mL, 30 mL, and 60 mL) were applied following the administration of 10 mL Gd (single dose) to a group of 4 normal volunteers (body weight 50–55 kg) using a mechanical MR injector (injection rate = 3.0 mL/s). Additionally, when performing a second test series, the saline volume remained constant, while the Gd volumes were varied from half doses to triple doses (5, 10, 20, and 30 mL Gd were given to every volunteer of the group). The signal intensity versus time (SI/T) curve at a measured region of interest (ROI) within the DAo was calculated. The bolus arrival time (BAT), the maximal signal‐to‐noise ratio (SNRmax), the bolus time length (BL; 75% and 80% maximum intensity duration), the slope of the SI/T curve, and the areas below the SI/T curve for both the 80% and 75% maximum intensity duration level (INT80% and INT75%) were calculated. The increase of saline flush volume from 30 to 60 mL caused significant bolus lengthening of approximately 50% (mean BL = 9.5 s, 10.3 s, and 15.4 s for 15 mL, 30 mL, and 60 mL saline flush volumes, respectively, measured as SI/T duration at the 75% SNRmax level). Using saline flush volumes equal to or higher than 30 mL increased the slope of the SI/T curve. A continuous increase of INT75%/80% by using higher saline flush volumes was found. Different saline and Gd volumes did not affect the SNRmax and the BAT. Only the low dose (0.05 mmol/kg Gd) showed a 17%–21.6% significantly lower SNRmax. The BL and the INT increased mainly by enlarging of applied Gd volume from single to double dose (BL75% and INT75% were 9.6 s and 1305, 12.3 s and 2121, 38.5 s and 6181, 37.8 s and 6613 for 5, 10, 20, and 30 mL applied Gd volume, respectively). The arterial bolus length benefits from increasing Gd and saline flush volumes due to increased venous bolus length and wash out effects of Gd within the injection site of the vein. Doses larger than a single dose are not needed to increase the SNR in contrast‐enhanced magnetic resonance angiography images of the thoracic aorta. J. Magn. Reson. Imaging 2001;13:568–576. © 2001 Wiley‐Liss, Inc.
Pulmonary ventilation‐perfusion MR imaging in clinical patients
Authors: Nakagawa Toshio , Sakuma Hajime , Murashima Shuichi , Ishida Nanaka , Matsumura Kaname , Takeda Kan
Published: August 2002

The purpose of this study was to evaluate the feasibility of comprehensive magnetic resonance (MR) assessment of pulmonary perfusion and ventilation in patients. Both oxygen‐enhanced ventilation MR images and first‐pass contrast‐enhanced perfusion MR images were obtained in 16 patients with lung diseases, including pulmonary embolism, lung malignancy, and bulla. Inversion recovery single‐shot fast spin‐echo images were acquired before and after inhalation of 100% oxygen. The overall success rate of perfusion MR imaging and oxygen‐enhanced MR imaging was 94% and 80%, respectively. All patients with pulmonary embolism showed regional perfusion deficits without ventilation abnormality on ventilation‐perfusion MR imaging. The results of the current study indicate that ventilation‐perfusion MR imaging using oxygen inhalation and bolus injection of MR contrast medium is feasible for comprehensive assessment of pulmonary ventilation‐perfusion abnormalities in patients with lung diseases. J. Magn. Reson. Imaging 2001;14:419–424. © 2001 Wiley‐Liss, Inc.
Effect of body coil electric field distribution on receive‐only surface coil heating
Authors: Guclu C. Celil
Published: August 2002

Although in the design of transmit RF coils, B1 homogeneity is crucial for good image quality, discussion of electric field (E‐field) distribution in the literature has been mostly limited to specific absorption rate (SAR) and patient loading (dielectric) effects. In this work, we report on a different aspect of E‐field: the receive‐only surface coil heating resulting from the voltage drop across the blocking (decoupling) networks and cable traps that are used to minimize the transmit field distortion. The results show that the z‐component (parallel to the coil cable) of the E‐field has a significant effect on the temperature rise in the surface coil. Therefore, in the receive‐only coil designs, it is not sufficient to consider only the induced voltage on the coil loop due to the B1 field, as is generally done in blocking network analysis calculations. The body coil E‐field distribution must be considered as well. J. Magn. Reson. Imaging 2001;14:484–487. © 2001 Wiley‐Liss, Inc.
Gas‐phase basicities for ions from bradykinin and its des‐arginine analogues
Authors: Ewing Nigel P. , Pallante Giovanni A. , Zhang Xin , Cassady Carolyn J.
Published: August 2002

Apparent gas‐phase basicities (GBapps) for [M + H]+ of bradykinin, des‐Arg1‐bradykinin and des‐Arg9‐bradykinin have been assigned by deprotonation reactions of [M + 2H]2+ in a Fourier transform ion cyclotron resonance mass spectrometer. With a GBapp of 225.8 ± 4.2 kcal mol−1, bradykinin [M + H]+ is the most basic of the ions studied. Ions from des‐Arg1‐bradykinin and des‐Arg9‐bradykinin have GBapp values of 222.8 ± 4.3 kcal mol−1 and 214.9 ± 2.3 kcal mol−1, respectively. One purpose of this work was to determine a suitable reaction efficiency ‘break point’ for assigning GBapp values to peptide ions using the bracketing method. An efficiency value of 0.1 (i.e. approximately 10% of all collisions resulting in a deprotonation reaction) was used to assign GBapps. Support for this criterion is provided by the fact that our GBapp values for des‐Arg1‐bradykinin and des‐Arg9‐bradykinin are identical, within experimental error, to literature values obtained using a modified kinetic method. However, the GBapps for bradykinin ions from the two studies differ by 10.3 kcal mol−1. The reason for this is not clear, but may involve conformation differences produced by experimental conditions. The results may be influenced by salt‐bridge conformers and/or by conformational changes caused by the use of a proton‐bound heterodimer in the kinetic method. Factors affecting the basicities of these peptide ions are also discussed, and molecular modeling is used to provide information on protonation sites and conformations. The presence of two highly basic arginine residues on bradykinin results in its high GBapp, while the basicity of des‐Arg1‐bradykinin ions is increased by the presence of two proline residues at the N‐terminus. The proline residue in the second position folds the peptide chain in a manner that increases intramolecular hydrogen bonding to the protonated N‐terminal amino group of the proline at the first position. Copyright © 2001 John Wiley & Sons, Ltd.
An intelligent data acquisition system for simultaneous screening of microsomal stability and metabolite profiling by liquid chromatography/mass spectrometry
Authors: Gu Ming , Lim Heng‐Keang
Published: August 2002

This paper describes the development of a mass spectrometer‐based, intelligent, programmable, sample‐selection data acquisition system with two unique features. One is that the system allows automatic determination of the mass to charge ratio (m/z) of an unknown compound and the utilization of the molecular ion information to perform selective ion monitoring (SIM) experiments for quantitation. The other is its decision‐making capability to select intelligently different samples and perform different experiments during data acquisition. These features were demonstrated by the application of the system to simultaneous screening for the microsomal stability and metabolite profiling of adatanserin. In this application, the data acquisition system continuously calculated the peak areas of adatanserin from SIM analyses of a batch of microsomal incubates stopped at various time points. Once the peak area of adatanserin had dropped to an arbitrarily predefined 60% of the initial value, the system made a decision to perform metabolite profiling of the sample. This decision initiated a series of automated operations, such as selecting a sample for re‐analysis, changing the data acquisition time and liquid chromatographic gradient and switching the SIM mode to the data‐dependent product ion scanning mode. The completed analysis of the batch of samples provided information both on the microsomal stability and on the metabolic profile of adatanserin. This simultaneous approach to investigating microsomal stability and metabolite profiling significantly increases the throughput for drug discovery support. Copyright © 2001 John Wiley & Sons, Ltd.
Prevalence of tick‐borne encephalitis virus in Ixodes ricinus ticks in Finland
Authors: Han Xiuqi , Aho Mika , Vene Sirkka , Peltomaa Miikka , Vaheri Antti , Vapalahti Olli
Published: August 2002

Approximately 20 cases of tick‐borne encephalitis (TBE) occur annually in Finland. The known endemic areas are situated mainly in the archipelago and coastal regions of Finland, with highest incidence in Åland islands. Ixodes ricinus panels collected in 1996–1997 from two endemic areas were screened for the presence of RNA. Two distinct RT‐PCR methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (FFD)/100 μl. One out of 20 pools (a total of 139 ticks) from Helsinki Isosaari Island and one out of 48 pools (a total of 450 ticks) from Åland were positive with both methods, whereas the remaining pools were negative. The observed overall frequency (0.34%) in ticks in endemic areas of Finland, was similar to the low incidence found by virus isolation in mice in the 1960s (0.5%). Viral RNA was detectable in a diluted sample representing 0.005% of a positive pool of ten nymphs suggesting that the viral RNA load within an infected tick pool was approximately equivalent to 20,000–200,000 FFD. Sequence analysis did not show geographical clustering of the Finnish strains, suggesting an independent emergence of different TBE foci from the south. TBE virus RNA positive ticks were not found in I. ricinus panels consisting of 130 pools (726 ticks) from Helsinki city parks or 41 pools (197 ticks) from Võrmsi Island in Estonia. J. Med. Virol. 64:21–28, 2001. © 2001 Wiley‐Liss, Inc.
Identification of key mutations in HIV reverse transcriptase gene can influence the clinical outcome of HAART
Authors: Setti Maurizio , Bruzzone Bianca , Ansaldi Filippo , Borrelli Paolo , Indiveri Francesco , Icardi Giancarlo
Published: August 2002

Therapeutic failures due to in vivo loss of drug sensitivity are still a major problem in AIDS care. Currently, the role of and methods for detecting resistant mutant strains in patients before therapeutic choices are still under debate. To investigate the relevance of screening for key mutations alone the commercial INNO‐LiPA HIV‐1 RT method was applied retrospectively to analyzing several HIV codons correlated with resistance to RTI (reverse‐transcriptase inhibitors) in sera from 62 patients before starting HAART protocols, selected on the basis of clinical parameters. INNO‐LiPA detected several resistant mutant strains, which were strictly consistent with previous selective pressure in the patients. A significant correlation between genotype pattern and response to HAART was found. The presence of key mutations associated with resistance to one or two RTI included in the protocol correlated with a decrease in treatment benefits, whereas patients with wild‐type or non‐resistant viral strains exhibited better response to HAART. Even if this information had been available when treatment was started, 45 of the patients would not have received different treatment. When compared with the total number of patients, the subgroup receiving a treatment that was considered retrospectively as consistent with the key mutation pattern exhibited a significantly better outcome. Although the interpretation of resistance‐related key mutations needs improvement, this surrogate LiPA method seems to maintain a predictive role in the management of HIV infection, and is less expensive. J. Med. Virol. 64:199–206, 2001. © 2001 Wiley‐Liss, Inc.
Full‐length genomic analysis of hepatitis B virus isolates in a patient progressing from hepatitis to hepatocellular carcinoma
Authors: Lin Xu , Qian Geng‐Sheng , Lu Pei‐Xing , Wu Li , Wen Yu‐Mei
Published: August 2002

In hepatitis B virus (HBV)‐endemic countries, the majority of hepatocellular carcinoma (HCC) arises in HBV carriers. High frequency of mutations at nucleotides 1762(A→T) and 1764(G→A) in the core promoter region have been described in HCC. Due to the differences in genetic backgrounds, environmental risk factors and random cellular insertion sites, it is difficult to analyze the possible roles of HBV variants detected in different HCC patients. In a follow‐up cohort study, an HBsAg‐positive asymptomatic carrier was diagnosed HCC within 4 years. Eleven full‐length HBV isolates, three from the first serum sample obtained 4 years pre‐HCC, and eight from serum sample, peri‐tumor and tumor tissue post‐HCC of this individual were sequenced and used to transfect HepG2 cells. When sequences were compared between pre‐ and post‐HCC isolates, no single mutation common to all post‐HCC isolates that differed from pre‐HCC isolates was found. Among all 11 isolates, there were 20 predicted amino acid substitutions shared by two or more post‐HCC isolates. These were located in the S(5), X(4), core(4), polymerase(4), pre‐S1(2) and pre‐S2(1) proteins. Possible roles of amino acid substitutions and enhanced replication efficiency in cells transfected by post‐HCC isolates are discussed. J. Med. Virol. 64:299–304, 2001. © 2001 Wiley‐Liss, Inc.
Acute self‐limiting hepatitis B after immunoprophylaxis failure in an infant
Authors: Komatsu Haruki , Fujisawa Tomoo , Sogo Tsuyoshi , Isozaki Atsushi , Inui Ayano , Sekine Isao , Kobata Makoto , Ogawa Yunosuke
Published: August 2002

The occurrence of acute hepatitis after failure of immunoprophylaxis in cases of mother‐to‐infant transmission of hepatitis B virus (HBV) is uncommon. Because immunoprophylaxis failure is caused by the emergence of an “a” determinant escape mutant, the infants usually become HBV carriers. To evaluate whether mutations in the S gene coding for the surface protein that contains the “a” determinant are associated with acute hepatitis after immunoprophylaxis failure, HBV DNA of an infant in with acute hepatitis developed with seroconversion to anti‐HBs antibodies at 12 months of age despite administration of anti‐hepatitis B immunoglobulin and hepatitis B vaccine was analyzed. The S gene from HBV DNA isolated from the serum of the infant at 12, 19, and 27 months of age was cloned and sequenced. Mutations affecting amino acid residues in the first loop within the “a” determinant (codons 124–147) were found at 12 months of age. Moreover, a novel deletion mutant, with a 1‐bp deletion at nucleotide 449 of the S gene, was found at 19 and 27 months of age. This deletion resulted in a frame shift and it introduced a stop codon (TAG) at codon 176. Because the open reading frame of the S gene is completely overlapped by the polymerase gene, mutations in the S gene may affect the polymerase gene. Based on this case, this study suggests that the observed frame‐shift mutation in the S gene might affect the polymerase protein and induce prompt suppression of viral replication. J. Med. Virol. 66:28–33, 2002. © 2002 Wiley‐Liss, Inc.
Molecular epidemiology of hepatitis B virus in Amsterdam 1992–1997*
Authors: van Steenbergen J.E. , Niesters H.G.M. , Op de Coul E.L.M. , van Doornum G.J.J. , Osterhaus A.D.M.E. , Leentvaar‐Kuijpers A. , Coutinho R.A. , van den Hoek J.A.R.
Published: August 2002

To gain insight into the spread of hepatitis B among various risk groups in Amsterdam a 6‐year (1992–1997) retrospective DNA sequencing study was carried out on isolates from stored sera from reported primary cases of acute hepatitis B infection. Cases were classified according to risk behavior, as determined in interviews. Of the available serum, a selected region of hepatitis B‐virus‐DNA was amplified and sequenced. The nucleotide alignments were subjected to phylogenetic tree analysis. When nucleotide alignments were subjected to phylogenetic analysis, the strains of 54 isolates, 26% of the 204 reported primary cases, clustered in five genotypes: A, C, D, E, and F. In genotype A, a cluster related to men having sex with men was identified. In genotype D, two subclusters could be identified: one was related to injecting drug use and another was related to the Moroccan population in Amsterdam. The remaining strains showed a high genetic variability within three different genotypes: F, E, and C. Of the 14 identical isolates in the “homosexual men cluster,” one was isolated from a female heterosexual. Of the 14 identical strains in the “drug users strain,” six were from non‐drug using heterosexual active individuals. In the cluster of twelve isolates related to hepatitis B‐endemic areas, probable modes of transmission were varied. Sequence analysis provides important insight into the spread of hepatitis B among various high‐risk groups. The analysis indicates that the prevention strategy in The Netherlands fails to stop transmission of hepatitis B from persistently infected individuals originating from hepatitis Bendemic countries. J. Med. Virol. 66:159–165, 2002. © 2002 Wiley‐Liss, Inc.
Genetic susceptibility to respiratory syncytial virus infection in inbred mice
Authors: Stark James M. , McDowell Susan A. , Koenigsknecht Vincent , Prows Daniel R. , Leikauf John E. , Le Vine Ann Marie , Leikauf George D.
Published: August 2002

Differences in the severity of respiratory syncytial virus (RSV)‐induced lower respiratory disease in infants have been attributed to multiple environmental and genetic factors. To identify the genetic factor(s) influencing RSV susceptibility, we examined RSV infection in eight inbred mouse strains. Lung RSV titers differed significantly between mouse strains: the RSV titers were 15‐fold higher in AKR/J (permissive) mice compared with C57BL/6J (resistant) mice at 4 days after inoculation. This strain‐specific difference in RSV titers suggested that susceptibility to RSV infection was attributable to genetic differences between strains. To examine the mode of inheritance of RSV susceptibility, F1 and backcross (F1 × AKR/J) progeny were infected and RSV titers determined. RSV titers in the F1 progeny were similar to those found in the resistant (C57BL/6J) parent, suggesting resistance was inherited as a dominant trait. The distribution of RSV titers in backcross progeny were discordant with that predicted for a single gene effect, suggesting susceptibility was influenced by more than one gene. These data suggest that RSV susceptibility is a multigenic trait that should be amenable to resolution by genomic analysis. J. Med. Virol. 67:92–100, 2002. © 2002 Wiley‐Liss, Inc.
On the suitability of GO/UTD modelling of microwave propagation in indoor environments
Authors: Torres R. P. , Valle L. , Domingo M. , Loredo S.
Published: August 2002

The main aim of this paper is to show the suitability of the geometrical optics and uniform theory of diffraction (GO/UTD) approach for modelling microwave propagation in indoor environments. Implementation details for an efficient method based on a combination of image theory and the binary space partitioning (BSP) algorithm to perform ray tracing are presented. The efficiency of the method allows a full three‐dimensional implementation of the GO/UTD approach. An extensive measurement champaign has been carried out in order to analyse the degree of accuracy achievable by the method. Some of these comparisons between measured and simulated data are presented, and a quantitative analysis of errors is made. The analysis reveals that the degree of precision in the calculation of the signal levels allows not only the signal mean level but also its statistics to be estimated accurately. The error in the mean level of the signal is less than 2 dB in the majority of cases, a maximum error of 3.6 dB having been obtained. The statistics of the signal fit Rice distributions very closely with different values of the rician parameterK. Finally, a brief study of the influence of the number of ray mechanisms considered (reflected, double reflected, etc.) on the accuracy and calculation times is also presented. Copyright © 2001 John Wiley & Sons, Ltd.
Differential postreceptor signaling events triggered by excitotoxic stimulation of different ionotropic glutamate receptors in retinal neurons
Authors: Santos Armanda E. , Carvalho Ana L. , Lopes Maria C. , Carvalho Arsélio P.
Published: August 2002

The aim of this work was to investigate whether excitotoxicity induced by overstimulation of different ionotropic glutamate receptors could trigger different intracellular signaling cascades. Cultured chick neuronal retina cells, essentially amacrine‐like, were particularly sensitive to the toxicity induced by non‐NMDA glutamate receptor agonists. One hour stimulation with 100 μM kainate induced a reduction of cell viability of about 44%, as assessed by the MTT test 24 hr after stimulation. Kainate‐induced toxicity was mediated through AMPA receptors. Glutamate (100 μM, 1 hr) reduced cell viability by 26%, essentially acting through N‐methyl‐D‐aspartate receptors. Five hours after stimulation, neuronal retina cells had an apoptotic‐like nuclear morphology. In retinal neurons, the excitotoxic stimulation, with either glutamate or kainate, induced a calcium‐dependent enhancement of the DNA‐binding activity of the activating protein‐1 (AP‐1) transcription factor, which was maximal 2 hr after stimulation. Glutamate induced a greater increase in the AP‐1 DNA‐binding activity than did kainate. Supershift assays using antibodies directed against different members of the Fos and Jun protein families showed that the AP‐1 complex in retinal neurons includes proteins of the Fos family, namely, Fra‐2, c‐Jun, and Jun D. The DNA‐binding activity of the nuclear factor‐κB transcription factor was not significantly changed upon excitotoxic stimulation with any agonist. Stimulation of glutamate receptors with 100 μM kainate or 100 μM glutamate for 2 min was sufficient to induce the activation of the extracellular signal‐regulated kinase (ERK). Inhibition of the ERK activation with the MEK inhibitors U 0126 and PD 98059 increased the toxicity induced by kainate but was without effect on the toxicity induced by glutamate. These results indicate that, although stimulation with both glutamate receptor agonists increased ERK phosphorylation, only kainate‐induced ERK activation correlates with the activation of a survival signaling pathway. Our results suggest that, in chick embryo retinal neurons, the signaling pathways that mediate excitotoxic cell death and neuroprotection are stimulus specific. J. Neurosci. Res. 66:643–655, 2001. © 2001 Wiley‐Liss, Inc.
Ammonia induces the mitochondrial permeability transition in primary cultures of rat astrocytes
Authors: Bai G. , Rama Rao K.V. , Murthy Ch.R.K. , Panickar K.S. , Jayakumar A.R. , Norenberg M.D.
Published: August 2002

Ammonia is a toxin that has been strongly implicated in the pathogenesis of hepatic encephalopathy (HE), and the astrocyte appears to be the principal target of ammonia toxicity. The specific neurochemical mechanisms underlying HE, however, remain elusive. One of the suggested mechanisms for ammonia toxicity is impaired cellular bioenergetics. Because there is evidence that the mitochondrial permeability transition (MPT) is associated with mitochondrial dysfunction, we determined whether the MPT might be involved in the bioenergetic alterations related to ammonia toxicity. Accordingly, we examined the mitochondrial membrane potential (Δψm) in cultured astrocytes and neurons using laser‐scanning confocal microscopy after loading the cells with the voltage‐sensitive dye JC‐1. We found that ammonia induced a dissipation of the Δψmin a time‐ and concentration‐dependent manner. These findings were supported by flow cytometry using the voltage‐sensitive dye tetramethylrhodamine ethyl ester (TMRE). Cyclosporin A, a specific inhibitor of the MPT, completely blocked the ammonia‐induced dissipation of the Δψm. We also found an increase in the mitochondrial permeability to 2‐deoxyglucose in astrocytes that had been exposed to 5 mM NH4Cl, further supporting the concept that ammonia induces the MPT in these cells. Pretreatment with methionine sulfoximine, an inhibitor of glutamine synthetase, blocked the ammonia‐induced collapse of Δψm, suggesting a role of glutamine in this process. Over a 24‐hr period, ammonia had no effect on the Δψmin cultured neurons. Collectively, our data indicate that ammonia induces the MPT in cultured astrocytes, which may be a factor in the mitochondrial dysfunction associated with HE and other hyperammonemic states. © 2001 Wiley‐Liss, Inc.
Glucose and lactate metabolism during brain activation
Authors: Dienel Gerald A. , Hertz Leif
Published: August 2002

The dependence of brain function on blood glucose as a fuel does not exclude the possibility that lactate within the brain might be transferred between different cell types and serve as an energy source. It has been recently suggested that 1) about 85% of glucose consumption during brain activation is initiated by aerobic glycolysis in astrocytes, triggered by demand for glycolytically derived energy for Na+‐dependent accumulation of transmitter glutamate and its amidation to glutamine, and 2) the generated lactate is quantitatively transferred to neurons for oxidative degradation. However, astrocytic glutamate uptake can be fuelled by either glycolytically or oxidatively derived energy, and the extent to which “metabolic trafficking” of lactate might occur during brain function is unknown. In this review, the potential for an astrocytic–neuronal lactate flux has been estimated by comparing rates of glucose utilization in brain and in cultured neurons and astrocytes with those for lactate release and uptake. Working brain tissue and isolated brain cells release large amounts of lactate. Cellular lactate uptake occurs by carrier‐mediated facilitated diffusion and is normally limited by its dependence on metabolism of accumulated lactate to maintain a concentration gradient. The rate of this process is similar in cultured astrocytes and glutamatergic neurons, and, at physiologically occurring lactate concentrations, lactate uptake corresponds at most to 25% of the rate of glucose oxidation, which accordingly is the upper limit for “metabolic trafficking” of lactate. Because of a larger local release than uptake of lactate and the necessity for rapid lactate clearance to maintain the intracellular redox state to support lactate production in the presence of normal oxygen levels, brain activation in vivo is probably, in many cases, accompanied by a substantial overflow of glycolytically generated lactate, both to different brain areas and under some conditions (spreading depression, hyperammonemia) to circulating blood. © 2001 Wiley‐Liss, Inc.
Pharmacodynamics of citicoline relevant to the treatment of glaucoma
Authors: Grieb Pawel , Rejdak Robert
Published: August 2002

Citicoline (exogenous CDP‐choline) is a nontoxic and well‐tolerated drug used in pharmacotherapy of brain insufficiency and some other neurological disorders, such as stroke, brain trauma, and Parkinson's disease. A few reports indicate that citicoline treatment may also be beneficial in glaucoma. Currently glaucoma is considered a neurodegenerative disease in which retinal ganglion cells (RGC) slowly die, likely in the apoptotic mechanism. Endogenous CDP‐choline is a natural precursor of cellular synthesis of phospholipids, mainly phosphatydylcholine (PtdCho). Enhancement of PtdCho synthesis may counteract neuronal apoptosis and provide neuroprotection. Citicoline, when administered, undergoes a quick transformation to cytidine and choline, which are believed to enter brain cells separately and provide neuroprotection by enhancing PtdCho synthesis; similar effect may be expected to occur in glaucomatous RGC. Furthermore, citicoline stimulates some brain neurotransmitter systems, including the dopaminergic system, and dopamine is known as a major neurotransmitter in retina and postretinal visual pathways. In a double‐blind, placebo‐controlled study, treatment of glaucoma resulted in functional improvement in the visual system noted with electrophysiological methods. Development of citicoline as a treatment for glaucoma is indicated. © 2002 Wiley‐Liss, Inc.
Plasma melatonin, pinealocyte morphology, and surface receptors/antigen expression on macrophages/microglia in the pineal gland following a high‐altitude exposure
Authors: Kaur C. , Srinivasan K.N. , Singh J. , Peng C.M. , Ling E.A.
Published: August 2002

The present study examined the effects of high‐altitude exposure on the pineal gland, the main source of production of melatonin. It was surmised that hypoxia experienced at high altitude, caused by decreased oxygen tension in the ambient air, might lead to some structural alterations in the pineal gland and, hence, affect its melatonin production. Adult Wistar rats were exposed to an altitude of 8,000 m for 2 hr in an altitude chamber and then sacrificed at various time intervals after the exposure. Normal rats kept at ground level were used as controls. Blood samples were collected at various time intervals for measurement of plasma melatonin level, and the pineal glands from both groups were processed for electron microscopy and immunohistochemistry. The plasma melatonin level showed a steady increase following altitude exposure peaking at 7 days and returned to control levels thereafter. Between 1 and 4 days after altitude exposure, the mitochondrial number and lipid droplets in the pinealocytes appeared to be reduced compared with those in control rats. At 7 days, however, the mitochondrial numbers and lipid droplets were noticeably increased. At the same time interval, the expression of complement type 3 receptors and major histocompatibility class II antigens as detected with the antibodies OX‐42 and OX‐6, respectively, in macrophages/microglia was up‐regulated compared with that in the control rats and those killed at earlier times. This was attributed to the increased serum melatonin after the altitude exposure. By 14 and 21 days, the ultrastructure of pinealocytes and immunoreactivity of macrophages/microglia were comparable with those in the control rats. We conclude from this study that an altitude exposure in rats leads to an increase in melatonin production, which returned to control levels with passage of time. © 2002 Wiley‐Liss, Inc.