bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the gonadal development and plasma levels of sex steroid hormones in diploid and triploid sea bass, Dicentrarchus labrax L.
Authors: Felip Alicia , Piferrer Francesc , Carrillo Manuel , Zanuy Silvia
Published: August 2002

The goal of this study was to compare the reproductive physiology of triploid and diploid European sea bass (Dicentrarchus labrax L.). Gonads of diploid and triploid fish (males and females) were examined both microscopically and macroscopically, together with the plasma levels of the major sex steroids produced (testosterone and estradiol‐17β) when fish were adults. Prior to sexual maturation, the gonadosomatic index (GSI) of triploid males was similar to that of diploids. However, the GSI in 4‐year‐old adult triploid males was 1.8 times lower than that of diploids (P < 0.05). All diploid males exhibited normal gonadal development. In contrast, in triploid males spermatogenesis was impaired during late meiosis, affecting severely spermiogenesis. This was achieved by an increasing imbalance in the amount of DNA present in daughter cells of the same type as spermatogenesis progressed, as demonstrated by abnormal cell sizes, culminating in inviable spermatids. Thus, no spermiating triploid fish were observed during 4 years, which included three full consecutive maturation cycles. Furthermore, the germ cells from triploids were significantly larger than those from diploids (P < 0.001). Seasonal profiles of plasma levels of testosterone in 4‐year‐old males were essentially similar in both ploidies. On the other hand, triploid females had rudimentary ovaries containing oogonia and primary oocytes that were arrested during meiotic prophase I, while diploid females exhibited all stages of ovarian development. Diploid females showed levels of testosterone and estradiol‐17β significantly higher than those of triploids (P < 0.05), in which no endocrine signs of maturation were observed at all. Regarding sex ratios, triploids had 10% more females than diploids (P < 0.05) but in both ploidies males predominated, as is usually found in this species under culture conditions. These results show that triploidy blocked the initial phases of meiosis in females and the latter ones in males, resulting in the absence of or reduced gonadal development, respectively. In conclusion, we provide an explanation for the lack of gonadal development in triploid male fish, and, to the best of our knowledge, we report for the first time a case in which induced triploidy completely blocks meiosis in both sexes, thus conferring functional sterility in the sea bass. J. Exp. Zool. 290:384–395, 2001. © 2001 Wiley‐Liss, Inc.
Fibroblast growth factors in regenerating limbs of Ambystoma: Cloning and semi‐quantitative RT‐PCR expression studies
Authors: Christensen Randolph N. , Weinstein Michael , Tassava Roy A.
Published: August 2002

Urodele amphibians (newts and salamanders) have the ability to regenerate amputated limbs throughout their life span. Because fibroblast growth factors (Fgfs) play important roles in developing limbs, we initiated studies to investigate these growth factors in regenerating limbs. Partial cDNAs of Fgf4, 8, and 10 were cloned from both the Mexican axolotl, Ambystoma mexicanum, and locally collected spotted salamander, Ambystoma maculatum, two salamanders well recognized for their regenerative capabilities. cDNAs from the two Ambystoma species were virtually identical, ranging from 97–100% nucleotide identity. Axolotl Fgf4, 8, and 10 showed nucleotide sequence identity with chick Fgf4, 8, and 10 of 79%, 83%, and 72%, respectively. RT‐PCR showed that these growth factors are expressed in regenerating axolotl limbs as well as in developing salamander larvae at the three‐digit forelimb stage. Fgf8 and 10 are upregulated during regeneration and thus may be involved in distal signaling similar to that of the developing chick limb. Fgf4, however, was undetectable by RT‐PCR in the distal tips of regenerates, suggesting that it does not play the same role in limb regeneration that it does in limb development. We also investigated the role these Fgfs may have in the nerve‐dependence of regeneration. They were expressed similarly in aneurogenic and innervated limbs, suggesting that they are not the neurotrophic factors responsible for nerve‐dependence. Denervation prevented Fgf8 and 10 upregulation, suggesting Fgf pathways are downstream of nerve‐dependence. These data highlight important similarities and differences in Fgf expression between limb development and limb regeneration. J. Exp. Zool. 290:529–540, 2001. © 2001 Wiley‐Liss, Inc.
Using heterochrony plots to detect the dissociated coevolution of characters
Authors: Schlosser Gerhard
Published: August 2002

The comparison of developmental sequences among species is notoriously difficult. Here, heterochrony plots are introduced as a new graphic method to detect temporal shifts in the development of characters in pair‐wise species comparisons. Plotting the timing of character development in one species against the timing of character development in another species allows us to compare a principally unlimited number of characters simultaneously and can detect whether suites of characters are dissociated from one another or not. Such heterochrony plots can be embedded into a comparative phylogenetic analysis in order to establish whether observed patterns of character codissociation are indeed due to their dissociated coevolution. Comparative phylogenetic analysis may also reveal multiple independent events of dissociated coevolution of the same suite of characters in a certain lineage, suggesting that the characters of this suite reciprocally constrain their evolutionary modifiability, thereby forming a unit of evolution. This ability to identify units of evolution is a prerequisite for assessing the validity of recently proposed scenarios, suggesting that modules of development and/or function tend to act as units of evolution. Starting from a detailed heterochrony plot comparing development in the direct developing frog Eleutherodactylus coqui and in the biphasically developing frog Discoglossus pictus, this comparative approach is illustrated focusing on the evolution of development of limbs, the nervous system and the pharyngeal arches in amphibians. J. Exp. Zool. (Mol. Dev. Evol.) 291:282–304, 2001. © 2001 Wiley‐Liss, Inc.
Responses of seminal vesicle and testicular β‐glucuronidase and β‐N‐acetylglucosaminidase to testosterone and some metabolites in Heteropneustes fossilis (Bloch)
Authors: Chowdhury I. , Joy K.P.
Published: August 2002

Intraperitoneal administration of testosterone for 20 days produced differential effects on β‐glucuronidase and β‐N‐acetylglucosaminidase (β‐Glc) activity in seminal vesicle (SV) and testis of the catfish Heteropneustes fossilis in preparatory phase (March). The lower dosages of 0.25 and 0.5 μg/g body weight (BW) of the steroid did not alter enzyme activity, and the higher dosages (1.0 and 2.0 μg/g BW) inhibited it significantly. Under in vitro conditions, addition of ascorbate and fructose (0.5–100 mM) to the incubation medium influenced enzyme activity differentially. At concentrations 0.5 and 1.0 mM, both fructose and ascorbate were ineffective except for the inhibition of testicular β‐Glc activity in the 1.0 mM ascorbate group. At higher concentrations (10, 50, and 100 mM), ascorbate inhibited enzyme activity in a concentration‐dependent manner. At 10 mM concentration of fructose, only testicular β‐Glc activity was inhibited, but at higher concentrations (50 and 100 mM), activities of both enzymes decreased uniformly in a concentration‐dependent manner. The addition of glucose had no significant effect on the enzyme activity at any of the concentrations tested. The results suggest that the inhibitory effect of testosterone on enzyme activity may be mediated through androgen‐dependent metabolites, such as fructose and ascorbate. J. Exp. Zool. 290:777–782, 2001. © 2001 Wiley‐Liss, Inc.
Coloring all directed paths in a symmetric tree, with an application to optical networks*
Authors: Gargano Luisa , Hell Pavol , Perennes Stephane
Published: August 2002

Let T be a symmetric directed tree, i.e., an undirected tree with each edge viewed as two opposite arcs. We prove that the minimum number of colors needed to color the set of all directed paths in T, so that two paths of the same color never use the same directed arc of T, is equal to the maximum number of different paths that contain the same arc of T. The proof implies a polynomial time algorithm for actually coloring the paths with the minimum number of colors. When only a subset of the directed paths is to be colored, the problem is known to be NP‐complete; we describe certain instances of the problem which can be efficiently solved. These results are applied to WDM (wavelength‐division multiplexing) routing in all‐optical networks. In particular, we solve the all‐to‐all gossiping problem in optical networks. © 2001 John Wiley & Sons, Inc. J Graph Theory 38: 183–196, 2001
A conveníent production of [13N]nitrogen for ventilation studies using a nitrogen gas target for 11C production
Authors: Bars D. Le
Published: August 2002

Taking advantage of the 14N(p,pn)13N reaction occuring during the 14N(p,α)11C carbon dioxide production, pure [13N]N2 suitable for PET ventilation studies was produced in a standard nitrogen gas target for 11C‐production (“carbon‐11 target”), after elimination of 11CO2 and short‐lived oxygens. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of [3(R)‐amino‐2(S)‐sulfhydryl‐5‐sulfonate]‐pentanoyl‐(S)‐3‐[125I]‐iodotyrosyl‐(S)‐aspartic acid: a radiolabelled inhibitor of aminopeptidase A
Authors: David‐Basei Christelle , Bischoff Laurent , Fournie‐Zaluski Marie‐Claude , Roques Bernard P.
Published: August 2002

In order to investigate the localization of aminopeptidase A in the central nervous system and peripheral organs, we have synthesized the first radiolabelled inhibitor of this enzyme. This molecule, [3(R)‐amino‐2(S)‐sulfhydryl‐5‐sulfonate]‐pentanoyl‐(S)‐3‐[125I]‐iodotyrosyl‐(S)‐aspartic acid, exhibited a Ki value of 4.8 nM for aminopeptidase A. A high purity was obtained with a specific activity of about 2,000 Ci/mmol at the end of the synthesis. Copyright © 2001 John Wiley & Sons, Ltd.
Digestive, salivary, and reproductive organs of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type
Authors: Ghanim Murad , Rosell Rosemarie C. , Campbell Leslie R. , Czosnek Henryk , Brown Judith K. , Ullman Diane E.
Published: August 2002

A microscopic analysis of the morphology and ultrastructure of the digestive, salivary, and reproductive systems of adult Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) B type was conducted using light, scanning, and transmission electron microscopy. The internal anatomy of B. tabaci was found to be similar to that reported for Trialeurodes vaporariorum. In a microscopic analysis of the salivary glands, we have shown that each primary salivary gland is composed of at least 13 cells varying in morphology and staining differentially, while the accessory salivary glands are composed of four morphologically similar cells. We analyzed the course of the alimentary canal in B. tabaci, demonstrated the internal morphology of the organs, and clarified the location of the filter chamber relative to other organs in the whitefly. Our observations confirm that the pair of structures extending from the connecting chamber are caeca that may aid in fluid movement through the midgut and are not Malpighian tubules, as previously suggested. We confirm an earlier finding that the whitefly lacks Malpighian tubules, having instead specialized Malpighian‐like cells within the filter chamber at the juncture with the internal ileum. Finally, we provide the first scanning electron microscopic analysis showing the reproductive organs of B. tabaci. Our investigation provides clarified terminology for several components of the digestive and excretory system. We also provide drawings and micrographs that will aid future researchers in localizing the internal organs of B. tabaci. We expect our analysis to provide a valuable tool for studying B. tabaci / plant virus interactions and physiological and biological aspects of this insect. J. Morphol. 248:22–40, 2001. © 2001 Wiley‐Liss, Inc.
Biomechanical scaling of the hominoid mandibular symphysis
Authors: Daegling David J.
Published: August 2002

Experimental investigation of mandibular bone strain in cercopithecine primates has established that the mandible is bent in the transverse plane during the power stroke of mastication. Additional comparative work also supports the assumption that the morphology of the mandibular symphysis is functionally linked to the biomechanics of lateral transverse bending, or “wishboning” of the mandibular corpus. There are currently no experimental data to verify that lateral transverse bending constitutes an important loading regime among hominoid primates. There are, however, allometric models from cercopithecoid primates that allow prediction of scaling patterns in hominoid mandibular dimensions that would be consistent with a mechanical environment that includes wishboning as a significant component. This study uses computed tomography (CT) scans to visualize cortical bone distribution in the anterior corpus of a sample of four genera of extant hominoids. From the cortical bone contours, area properties of the mandibular symphysis are calculated, and these variables are subjected to an allometric analysis to detect whether scaling of jaw dimensions are consistent with a wishboning loading regime. Scaling of the hominoid symphysis recalls patterns observed in cercopithecoid monkeys, which lends indirect support for the hypothesis that wishboning is an integral part of the masticatory loading environment in living apes. Inclination of the symphysis, rather than changes in cross‐sectional shape or development of the superior transverse torus, represents a morphological solution for minimizing the potentially harmful effects of wishboning in the jaws of these primates. J. Morphol. 250:12–23, 2001. © 2001 Wiley‐Liss, Inc.
1‐X‐3 motif in inter‐protein recognition: structures, widespreading and possible practical application
Authors: Verevka S. V. , Miroshnychenko O. S.
Published: August 2002

Similarities in the discrete mode and size of contact areas of a wide range of protein complexes allows us to suggest the existence of a limited number of types of inter‐protein interactions. Comparison of structures of bound determinants indicates that the double‐module, 1‐X‐3 type of motif is widespread in recognition processes. Thus, in many cases, the sites of ligand recognition are formed by two significant amino acids and separated by insignificant ones. Typical examples of such motifs are the RGD sequence of some adhesive and haemostatic proteins, the primary sites for plasminogen sorption on the fibrin network, the reactive sites of protein inhibitors of serine proteinases, and the sites for activation of the hydrolysis of protein pro‐forms and receptors. It is assumed that there is widespread double‐module determinants in many inter‐protein interactions. Copyright © 2001 John Wiley & Sons, Ltd.
Temperature differentially affects encounter and docking thermodynamics of antibody–antigen association
Authors: Lipschultz Claudia A. , Yee Anthony , Mohan S. , Li Yili , Smith‐Gill Sandra J.
Published: August 2002

Using BIACORE SPR, we have examined the mechanism of temperature effects on the binding kinetics of two closely related antibody Fabs (H10 and H26) which recognize coincident epitopes on hen egg‐white lysozyme (HEL), and whose association and dissociation kinetics are best described by the two‐step conformational change model which we interpret as molecular encounter and docking. Time‐course series data obtained at a series of six temperatures (6, 10, 15, 25, 30 and 37 °C) showed that temperature differentially affects the rate constants of the encounter and docking steps. Docking is more temperature‐sensitive than the encounter step, and energetically less favorable at higher temperatures. At elevated temperatures, the time required for docking is longer and the apparent increase in off‐rate reflects the greater proportion of the molecules failing to dock and remaining in the less stable encounter state. As a consequence, distribution of free energy change between the encounter and docking steps is altered. At physiological temperature (37 °C) the docking step of the H26 complex is energetically unfavorable and most complexes essentially do not dock. There is a significant decrease in total free energy change of the H26 complex at higher temperatures. Elevated temperature changes the rate‐limiting step of H26–HEL association from the encounter to the docking step, but not that of H10–HEL. Our results indicate that the mechanism by which elevated temperature reduces the affinities of antigen–antibody complexes is to decrease the net docking rate, and/or stability of the docked complex; at higher temperatures, a smaller proportion of the complexes actually anneal to a more stable docked state. This mechanism may have broad applicability to other receptor–ligand complexes. Published in 2002 by John Wiley & Sons, Ltd.
Sodium T2* relaxation times in human heart muscle
Authors: Pabst Thomas , Sandstede Joern , Beer Meinrad , Kenn Werner , Neubauer Stefan , Hahn Dietbert
Published: August 2002

Purpose

To determine sodium transverse relaxation (T2*) characteristics for myocardium, blood and cartilage in humans.

Methods

T2* measurements were performed using a 3D ECG‐gated spoiled gradient echo sequence. A 1.5 Tesla clinical scanner and a 23Na heart surface coil were used to examine eight healthy volunteers. In biological tissue, the sodium 23 nucleus exhibits a two‐component T2 relaxation due to the spin 3/2 and its quadrupolar nature. The long T2* components of normal myocardium, blood, and cartilage were quantified. For myocardium, the T2* was determined separately for the septum, anterior wall, lateral wall, and posterior wall.

Results

The long T2* relaxation time components of 13.3 ± 4.3 msec (septum 13.9 ± 3.2 msec, anterior wall 13.8 ± 5.4 msec, lateral wall 11.4 ± 4.1 msec, posterior wall 14.1 ± 3.7 msec), 19.3 ± 3.3 msec, and 10.2 ± 1.6 msec, were significantly different for myocardium, blood, and cartilage, respectively (P < 0.00001, Friedman's ANOVA).

Conclusion

Measurement of 23Na T2* relaxation times is feasible for different regions of the human heart muscle, which might be useful for the evaluation of cardiac pathologies. J. Magn. Reson. Imaging 2002;15:215–218. © 2002 Wiley‐Liss, Inc.
Accuracy of segmented MR velocity mapping to measure small vessel pulsatile flow in a phantom simulating cardiac motion
Authors: Arheden Håkan , Saeed Maythem , Törnqvist Erna , Lund Gunnar , Wendland Michael F , Higgins Charles B , Ståhlberg Freddy
Published: August 2002

The purpose of this study was to investigate the accuracy of conventional, segmented, and echo‐shared MR velocity mapping sequences to measure pulsatile flow in small moving vessels using a phantom with simulated cardiac motion. The phantom moved either cyclically in‐plane, through‐plane, in‐ and through‐plane, or was stationary. The mean error in average flow was –2% ± 3% (mean ± SD) for all sequences under all conditions, with or without background correction, as long as the region of interest (ROI) size was equal to the vessel cross‐sectional size. Overestimation of flow as a result of an oversized ROI was less than 20%, and independent of field of view (FOV) and matrix, as long as the offset in angle between the imaging plane and flow direction was less than 10 degrees. Segmented velocity mapping sequences are surprisingly accurate in measuring average flow and render flow profiles in small moving vessels despite the blurring in the images due to vessel motion. J. Magn. Reson. Imaging 2001;13:722–728. © 2001 Wiley‐Liss, Inc.
Determination of famotidine in low‐volume human plasma by normal‐phase liquid chromatography/tandem mass spectrometry
Authors: Zhong Ling , Eisenhandler Roy , Yeh Kuang C.
Published: August 2002

A rapid, sensitive and robust assay procedure using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) for the determination of famotidine in human plasma and urine is described. Famotidine and the internal standard were isolated from plasma samples by cation‐exchange solid‐phase extraction with benzenesulfonic acid (SCX) cartridges. The urine assay used direct injection of a diluted urine sample. The chromatographic separation was accomplished by using a BDS Hypersil silica column with a mobile phase of acetonitrile–water containing trifluoroacetic acid. The MS/MS detection of the analytes was set in the positive ionization mode using electrospray ionization for sample introduction. The analyte and internal standard precursor–product ion combinations were monitored in the multiple‐reaction monitoring mode. Assay calibration curves were linear in the concentration range 0.5–500 ng ml−1 and 0.05–50 µg ml−1 in plasma and urine, respectively. For the plasma assay, a 100 µl sample aliquot was subjected to extraction. To perform the urine assay, a 50 µl sample aliquot was used. The intra‐day relative standard deviations at all concentration levels were <10%. The inter‐day consistency was assessed by running quality control samples during each daily run. The limit of quantification was 0.5 ng ml−1 in plasma and 0.05 µg ml−1 in urine. The methods were utilized to support clinical pharmacokinetic studies in infants aged 0–12 months. Copyright © 2001 John Wiley & Sons, Ltd.
Reactions of BBrn+ (n = 0–2) at fluorinated and hydrocarbon self‐assembled monolayer surfaces: observations of chemical selectivity in ion–surface scattering
Authors: Wade Nathan , Shen Jianwei , Koskinen Jere , Cooks R. Graham
Published: August 2002

Ion–surface reactions involving BBrn+ (n = 0–2) with a fluorinated self‐assembled monolayer (F‐SAM) surface were investigated using a multi‐sector scattering mass spectrometer. Collisions of the B+ ion yield BF2+ at threshold energy with the simpler product ion BF+· appearing at higher collision energies and remaining of lower abundance than BF2+ at all energies examined. In addition, the reactively sputtered ion CF+ accompanies the formation of BF2+ at low collision energies. These results stand in contrast with previous data on the ion–surface reactions of atomic ions with the F‐SAM surface in that the threshold and most abundant reaction products in those cases involved the abstraction of a single fluorine atom. Gas‐phase enthalpy data are consistent with BF2+ being the thermodynamically favored product. The fact that the abundance of BF2+ is relatively low and relatively insensitive to changes in collision energy suggests that this reaction proceeds through an entropically demanding intermediate at the vacuum–surface interface, one which involves interaction of the B+ ion simultaneously with two fluorine atoms. By contrast with the reaction of B+, the odd‐electron species BBr+· reacts with the F‐SAM surface to yield an abundant single‐fluorine abstraction product, BBrF+. Corresponding gas‐phase ion–molecule experiments involving B+ and BBr+· with C6F14 also yield the products BF+· and BF2+, but only in extremely low abundances and with no preference for double fluorine abstraction. Ion–surface reactions were also investigated for BBrn+ (n = 0–2) with a hydrocarbon self‐assembled monolayer (H‐SAM) surface. Reaction of the B+ ion and dissociative reactions of BBr+· result in the formation of BH2+, while the thermodynamically less favorable product BH+· is not observed. Collisions of BBr2+ with the H‐SAM surface yield the dissociative ion–surface reaction products, BBrH+ and BBrCH3+. Substitution of bromine atoms on the projectile by hydrogen or alkyl radicals suggests that Br atoms may be transferred to the surface in a Br‐for‐H or Br‐for‐CH3 transfer reaction in an analogous fashion to known transhalogenation reactions at the F‐SAM surface. The results for the H‐SAM surface stand in contrast to those for the F‐SAM surface in that enhanced neutralization of the primary ions gives secondary ion signals one to two orders of magnitude smaller than those obtained when using the F‐SAM surface, consistent with the relative ionization energies of the two materials. Copyright © 2001 John Wiley & Sons, Ltd.
Lipid A structure of Pseudoalteromonas haloplanktis TAC 125: use of electrospray ionization tandem mass spectrometry for the determination of fatty acid distribution
Authors: Corsaro Maria Michela , Piaz Fabrizio Dal , Lanzetta Rosa , Parrilli Michelangelo
Published: August 2002

The use of electrospray Ionization (ESI) tandem mass spectrometry (MS/MS) for the structural determination of the lipid A components of the psychrophilic bacterium Pseudoalteromonas haloplanktis TAC 125 is reported. The lipid A contains the classical bisphosphorylated β‐(1′ → 6)‐linked D‐glucosamine disaccharide with 3‐hydroxydodecanoyl residues (12 : 0 (3‐OH)) linked both as esters and amides to 2′, 3′ (distal glucosamine) and 2, 3 positions (proximal glucosamine) of the sugar backbone. The hydroxyl of 12 : 0 (3‐OH) fatty acid linked at the 3′ position is esterified by a dodecanoyl residue (12 : 0). In addition to the pentaacyl component, a minor tetraacyl lipid A, lacking the acyl residue at position 3, was also found in the lipid A fraction. The advantage of this MS technique for the investigation of the intra‐ring fragmentation, which is useful for the determination of fatty acyl residue distribution on each glucosamine unit, is emphasized. Copyright © 2002 John Wiley & Sons, Ltd.
Influence of the dynamics of the hypervariable region 1 of hepatitis C virus (HCV) on the histological severity of HCV recurrence after liver transplantation
Authors: Sánchez‐Fueyo Alberto , Giménez‐Barcons Mireia , Puig‐Basagoiti Francesc , Rimola Antoni , María Sánchez‐Tapias Jose , Sáiz Juan Carlos , Rodés Juan
Published: August 2002

Recurrence of hepatitis C virus (HCV) infection after liver transplantation is almost universal and usually leads to chronic hepatitis with different degrees of severity. The pathogenic mechanisms underlying the variable outcome of HCV infection recurrence are not well defined, but recent data suggest that the dynamics of HCV quasispecies may be involved. HCV quasispecies evolution was traced by longitudinal single strand conformation polymorphism, direct sequencing, and cloning analyses of pre‐ and post‐transplant HCV‐1b isolates from patients with histologically severe (seven cases) or mild or moderate (nine cases) HCV infection recurrence. Differences between the two groups of patients that concerned the level of viremia or the degree of HCV quasispecies complexity and diversity were not observed at any of the three time points analyzed. However, emergence of nucleotide and amino acid changes during the 12 months follow‐up was significantly more frequent in patients with mild or moderate than in those with severe HCV infection recurrence. The ratio of non‐synonymous to synonymous nucleotide substitutions 12 months after transplantation was also greater in the former, suggesting that the HVR1 of HCV is under stronger selective pressure in these subjects. These findings suggest that the degree of amino acid diversification in the HVR1 of HCV, which probably reflects the strength of immune pressure on HCV, is inversely related to the histological severity of HCV infection recurrence. J. Med. Virol. 65:266–275, 2001. © 2001 Wiley‐Liss, Inc.
Sensitive detection and differentiation of Sapporo virus, a member of the family Caliciviridae, by standard and booster nested polymerase chain reaction
Authors: Honma Shinjiro , Nakata Shuji , Sakai Yoshiyuki , Tatsumi Masatoshi , Numata‐Kinoshita Kazuko , Chiba Shunzo
Published: August 2002

Norwalk virus and Sapporo virus (SV) were approved as type species of the genus Norwalk‐like viruses and the genus Sapporo‐like viruses, respectively, in the family Caliciviridae. Nested polymerase chain reaction (PCR), using newly designed primers in the RNA‐dependent RNA polymerase region, was developed to detect and differentiate viruses in the three genetic groups of SV based on the relative size of the PCR products obtained. In addition, a booster nested PCR that performs nested PCR in a single tube was introduced to reduce the chance of contamination during the procedure of standard nested PCR. The specificity of the newly developed PCR was confirmed by testing 77 stool specimens and 16 tissue culture fluids derived from growth of unrelated viruses. The sensitivity of the nested PCR was compared with the conventional PCR using Sapp35/Sapp36 primer pair by testing the three cDNA clones obtained from viruses in the SV/SV82, the SV/London92, and the SV/Parkville virus, respectively. This assay can detect SV in a more sensitive way than the conventional PCR and Southern hybridization. Sensitive and suitable methods to detect and differentiate SV are required to obtain accurate epidemiological data on these viruses and the standard and booster nested PCR should be a very useful tool for this purpose. J. Med. Virol. 65:413–417, 2001. © 2001 Wiley‐Liss, Inc.
Failure of stavudine‐lamivudine combination therapy in antiretroviral‐naive patients with AZT‐Like HIV‐1 resistance mutations
Authors: Sarmati Loredana , Nicastri Emanuele , Parisi Saverio Giuseppe , D'Ettorre Gabriella , Narciso Pasquale , Mancino Giorgio , Gallo Isa , Abbadessa Vincenzo , Dalle Nogare Ernesto Renato , Traina Cino , Vullo Vincenzo , Andreoni Massimo
Published: August 2002

To analyze the clinical relevance of AZT resistance mutations in AZT‐naive patients, 56 HIV‐1 seropositive patients treated for 18 months with stavudine/lamivudine (27 patients) or AZT/lamivudine (29 patients) were studied. AZT‐like resistance mutations were found in 13 out of 29 (44%) patients treated with AZT/lamivudine and in 11 out of 27 (40%) patients treated with stavudine/lamivudine. No stavudine or multi‐drug resistance mutations were detected. After 26 months of treatment more than 60% of patients showed a virological failure. Among 10 patients failing treatment with stavudine/lamivudine, 9 had AZT‐like resistance mutations. The phenotypic test, performed on HIV‐1 strains isolated from six of these nine patients, showed a resistance to AZT in five isolates and to stavudine in two isolates. The genotypic pattern of the latter two isolates showed the combined mutations M184V plus R211K and L214F. AZT‐like resistance mutations in AZT‐naive patients seem to correlate with a virological failure during long‐term stavudine therapy. J. Med. Virol. 65:631–636, 2001. © 2001 Wiley‐Liss, Inc.
Genetic variability of the V1 and V2 env domains of SIVcpz‐ant and neutralization pattern of plasma viruses in a chimpanzee infected naturally
Authors: Ondoa Pascale , Davis David , Willems Betty , Heyndrickx Leo , Kestens Luc , van der Berg Ingrid , Coppens Sandra , Janssens Wouter , Heeney Jonathan , van der Groen Guido
Published: August 2002

Specific neutralizing epitope changes have been observed in a chimpanzee infected naturally with SIVcpz, which differ from HIV‐1 infecting humans. To characterize further these changes, a longitudinal study of env genomic sequence variation of SIVcpz‐ant isolates was undertaken in this animal. The V1 and V2 regions of the env were determined to arise from specific recombination events. To determine whether recombination of the V1 and V2 domains was possibly associated with the emergence of neutralization escape viruses, envelope sequences and gene length polymorphisms from PBMC and plasma viral variants were studied over a 7‐year period. PBMCs and plasma‐associated infectious virus titers as well as plasma RNA viral loads were monitored longitudinally. The first 5 viruses isolated from the plasma were found to be neutralization escape variants. Sequence analysis of their V1 and the V2 regions indicated that a 20 amino acid stretch of the V1 region had undergone recombination and was also associated with the emergence of isolates eliciting strong neutralization responses. These findings support the hypothesis that recombination of the V1 and V2 regions of the envelope play a role in neutralization escape of SIVcpz in chimpanzees infected naturally. Furthermore, the data confirm that the neutralizing antibody response plays an important role in the decline of plasma infectious virus titers in HIV‐1 related SIVcpz nonpathogenic infection. J. Med. Virol. 65:765–776, 2001. © 2001 Wiley‐Liss, Inc.
TLM for diffusion: the artefact of the standard initial conditions and its elimination within an abstract TLM suite
Authors: Enders Peter , Cogan Donard de
Published: August 2002

We demonstrate both analytically and numerically, that for the TLM algorithm for numerically solving the diffusion equation the standard initial conditions for the incident voltage pulses in terms of the initial concentration (or temperature) distribution introduce a significant numerical error. We discover the origin of this error and present an alternative prescription for computing the node voltages at the first time step which removes this artefact and exhibits distinctly improved numerical accuracy. For this, we introduce the term abstract TLM suite (ATS). An ATS is a numerical scheme which formally parallels a TLM scheme, but the scattering coefficients, ρ and τ, may assume values outside the interval [−1, 1] or may not correspond to the values of a real TLM network. Copyright © 2001 John Wiley & Sons, Ltd.
Finding new candidate genes for learning and memory
Authors: Leil Tarek A. , Ossadtchi Alex , Cortes James S. , Leahy Richard M. , Smith Desmond J.
Published: August 2002

The genetic mechanisms underlying learning and memory remain mysterious, but many of the genes are likely to be expressed in the hippocampus, a region pivotal to this process. We used a 9,000 gene microarray to examine differences in hippocampal gene expression between two F1 hybrid mouse strains that perform well on the Morris water maze and two inbred strains that perform poorly. This resulted in identification of 27 differentially expressed genes, which could be used to place the F1 hybrid and inbred strains into separate clusters based on singular value decomposition. Most of the genes have unknown function, but those with known functions may provide clues to the molecular mechanisms of learning. Using multiple strains to narrow down the number of candidate genes should be a useful general approach to genome‐wide studies of behavioral and other complex traits. © 2002 Wiley‐Liss, Inc.
A population of oligodendrocytes derived from multipotent neural precursor cells expresses a cholinergic phenotype in culture and responds to ciliary neurotrophic factor
Authors: MacDonald S.C. , Simcoff R. , Jordan L.M. , Dodd J.G. , Cheng K.W. , Hochman S.
Published: August 2002

Because oligodendrocytes and their precursors possess receptors for classical transmitters, and neurotransmitters such as glutamate and noradrenaline can mediate oligodendroglial proliferation and differentiation, it is possible that other neurotransmitters can also exert regulatory roles in oligodendrocyte function. We used mitogen‐proliferated multipotent neuroepithelial precursors (neurospheres) and identified oligodendroglia that expressed markers traditionally found in cholinergic neurons. Regardless of culture conditions, there existed a large population of cells that resembled oligodendrocytes morphologically and coexpressed the oligodendrocyte‐specific marker galactocerebroside (GalC) and the acetylcholine (ACh)‐synthesizing enzyme choline acetyltransferase (ChAT). These cells did not express neuronal markers, and whole‐cell recordings from cells with similar morphology displayed only outward currents in response to depolarizing voltage steps, further supporting their oligodendroglial identity. Another cholinergic marker, the vesicular ACh transporter, was also detected in GalC+ oligodendrocytes. Furthermore, neurospheres cultured in the presence of the cholinergic receptor antagonist atropine showed a decrease in the number of GalC+ spheres, implicating the muscarinic ACh receptor in oligodendrocyte development. The actions of neurotrophins and ciliary neurotrophic factor (CNTF) on these ChAT+ oligodendrocytes were examined. Among these, CNTF treatment significantly increased oligodendrocytic process outgrowth. These results demonstrate classical cholinergic neuronal markers in oligodendrocytes as well as an effect of muscarinic receptor blockade on oligodendrocyte differentiation. © 2002 Wiley‐Liss, Inc.
Altered expression of glutamate transporters under hypoxic conditions in vitro
Authors: Hsu Leigh , Rockenstein Edward , Mallory Margaret , Hashimoto Makoto , Masliah Eliezer
Published: August 2002

Regulation of extracellular excitotoxins by glial and neuronal glutamate transporters is critical to maintain synaptic terminal integrity. Factors interfering with the normal functioning of these transporters might be involved in neurodegeneration. Among them, recent studies have shown that hypoxia alters glutamate transporter function; however, it is unclear if hypoxia has an effect on the expression of glutamate transporters and which intracellular signaling pathways are involved. The C6 rat glial and GT1–7 mouse neuronal cell lines were exposed to hypoxic conditions (5% CO2, 95% N2) and levels of glutamate transporter mRNA were determined by ribonuclease protection assay. After 21 hr, there was a 100% increase in levels of rat excitatory amino acid transporter 3 (EAAT3) mRNA in C6 cells and a 600% increase in levels of murine EAAT2 mRNA in GT1–7 cells. There was a similar increase in mRNA levels after hypoxia in C6 cells transfected with human EAAT2, whereas reoxygenation normalized the expression levels of glutamate transporters. Although the expression of EAATs was associated with increased immunoreactivity by Western blot, functioning of the transporters was decreased as evidenced by D‐aspartate uptake. Finally, although the protein kinase C stimulator phorbol‐12‐myristate‐13‐acetate enhanced EAAT2 mRNA levels after hypoxia, protein kinase C inhibitor bisindolylmaleimide I had the opposite effect. Taken together, this study suggests that the hypoxia is capable of upregulating levels of EAATs via a protein kinase C‐dependent compensatory mechanism. This increased expression is not sufficient to overcome the decreased functioning of the EAATs associated with decreased ATP production and mitochondrial dysfunction. J. Neurosci. Res. 64:193–202, 2001. © 2001 Wiley‐Liss, Inc.
Spatial and temporal persistence of mean monthly temperature on two GCM grid cells
Authors: Hoff C.
Published: August 2002

The study investigates a simple statistically based scheme for translating large scale general circulation model (GCM) information to local scale where natural and socio‐economic environments are dependent on climatic variables. Two GCM grid cells were chosen, one centred on Montpellier (France), the other on Sevilla (Spain). For each meteorological station over these cells, the relative values of mean monthly temperature compared with the GCM grid cell mean were expressed as percentages, and were called ‘relative temperatures’ (RT). Using geostatistical procedures, the spatial structure of RT was sought on both GCM grid cells, with the altitude as external drift. The months of January and July were studied during the 1979–1993 period. For each month, the characteristics of the variograms of RT are close for each year of the period. There is also a good inter‐annual persistence of spatial patterns of RT when the correlation between altitude and RT is significant. The results will be of great interest for easily estimating local values of mean monthly temperature at any place within each grid cell without further calculation. Copyright © 2001 Royal Meteorological Society
Spectral-luminescent effects in heterometallic complexes of crown-porphyrins
Authors: KOROVIN YU. , ZHILINA Z. , RUSAKOVA N. , KUZ'MIN V. , VODZINSKY S. , ISHKOV YU.
Published: August 2002

New complexes of ytterbium with porphyrins containing crown- and other oxygen-containing cyclic substituents were obtained. The absorption, excitation, ligand luminescence and 4f-luminescence spectra have been investigated. It has been shown that 4f-luminescence of ytterbium Yb ( III ) ions was a result of the intramolecular energy transfer from the triplet level of the ligands to the resonance 2F5/2 level of Yb ( III ). It has been also established that in presence of alkali metal Na , K and Cs the dimer complexes (sandwich-type) of ytterbium-crown-porphyrin were formed. Molecular luminescence of the porphyrin matrix was quenched completely in these dimers, but at the same time the quantum yield and lifetime of 4f-luminescence increase in the complexes.
Spectroscopic studies of the interaction of cobalt(II) N,N',N″,N‴-tetramethyltetra-3,4-pyridinoporphyrazine with amino acids and nitrogen oxides
Authors: THAMAE MAMOTHIBE A. , NYOKONG TEBELLO
Published: August 2002

The interaction of histidine, cysteine, NO and nitrite with cobalt(II) N,N',N″,N‴-tetramethyltetra-3,4-tetrapyridinoporphyrazine ([ Co II tmtppa ]4+) is reported. Metal-based autoreduction of [ Co II tmtppa ]4+ occurs with the formation of the [ Co I tmtppa (-2)]3+ species in the presence of histidine and cysteine. Kinetic data for the auto reduction of [ Co II tmtppa ]4+ in the presence of these amino acids gave the rate constants k f = 2.1 × 101 and 2.8 dm3 mol-1 s-1, for cysteine and histidine, respectively. One molecule of NO or nitrite was found to coordinate to the [ Co II tmtppa ]4+ species. The equilibrium and rate constants for the coordination of the nitric oxide were K = 2.3 × 104 dm 3 mol -1 and k f = 7.5 dm 3 mol -1 s -1, respectively. The coordination of nitrite to [ Co II tmtppa ]4+ occurred with an equilibrium constant of K = 2.0 × 102 dm 3 mol -1 and a rate constant of k f = 4.0 × 10-3 dm 3 mol -1 s -1. There was no evidence for the coordination of two molecules of nitrite to the [ Co II tmtppa ]4+ species.
Synthesis of organo-soluble metallophthalocyanines bearing electron-withdrawing substituents
Authors: SANCHEZ MURIEL , FACHE ERIC , BONNET DIDIER , MEUNIER BERNARD
Published: August 2002

The syntheses of organo-soluble metallophthalocyanines having sulfo- and sulfonamido- electron-withdrawing substituents are reported. The simple cation exchange of the readily available tetrasodium salt of metallo-sulfophthalocyanines 1( M = Ni , Co , Fe , Cr ) by alkylammonium salts afforded the sulfophthalocyanines 2 and 3 in good yields. Complexes 2 featuring two long C 18 alkyl chains are only soluble in organic solvents while tetrabutylammonium counter ions exhibit a dual solubility in both organic solvents and water for compounds 3. The tetrasulfonamidophthalocyanine complexes 5–7 with four C8, four C18 or eight C8 alkyl chains have been obtained after chlorination of the sulfophthalocyanines 1 leading to the chlorosulfonyl derivatives 4, followed by reaction with various substituted amines. The synthesis of the chromium precursors with tetrasulfo and tetrachlorosulfonyl substituents is also described.
The origin and flux of icebergs released into the Last Glacial Maximum Northern Hemisphere oceans: the impact of ice‐sheet topography
Authors: Bigg Grant R. , Wadley Martin R.
Published: August 2002

The precipitation fields of a palaeoatmospheric general circulation model are used to derive estimates of the geographical distribution, and flux, of icebergs from the Laurentide, Fennoscandinavian and eastern Siberian ice‐sheets at the Last Glacial Maximum (LGM). The atmospheric model fields from LGM simulations using CLIMAP or Peltier (ICE‐4G) ice orography were studied, to test the sensitivity of the predicted flux. The estimated Northern Hemispheric LGM iceberg flux is 3500–4000 km3 yr−1, of which about 60% issued directly into the North Atlantic. The iceberg flux from the St Lawrence area is of similar significance to that issuing from Hudson Strait in all estimates. Both the North Pacific and the Arctic received substantial iceberg fluxes (ca. 700 km3 yr−1), with relatively minor differences occurring between the two ice‐sheet reconstructions. Apparent discrepancies between Arctic deep‐sea core samples of ice‐rafted debris and our estimates of mean glacial iceberg flux may be ascribed to coastal trapping of bergs, the existence of floating ice tongues or a rapid exit of icebergs from the Arctic basin into the Greenland Sea through the Fram Strait. Copyright © 2001 John Wiley & Sons, Ltd.
A SERS probe of adenyl residues available for intermolecular interactions. Part I—adenyl ‘fingerprint’
Authors: Grajcar Lydie , Baron Marie‐Hélène
Published: August 2002

This work validated a SERS probe able to compare adenyl reactivity in DNA and RNA. A Creighton silver colloid including adenine (A) [or 2′‐deoxyadenosine 5′‐phosphate (pdA)] from 2 × 10−3 to 2 × 10−8 M is stabilized in the absence or presence of chloride. Concentration‐dependent SER spectral profiles reveal how A may interact with (Ag)n+ sites. At concentration ≥2 × 10−5 M adsorption of (A)n clusters prevents the colloid from undergoing salt effects. Adsorption via N1/N3 is allowed whereas C6NH2 is involved in self‐association. At [A] <2 × 10−5 M with chloride, hydrogen bonding between chloride and the C6NH2 group enhances C6N electronegativity, which assists C6N/N7 cooperative adsorption. Complex A(Cl−) entities compete with individual chloride ions for adsorption on silver. Very similar C6N/N7 adenyl adsorption occurs for pdA but only above 2 × 10−5 M. Chloride–adenyl bonding is reduced and pdA self‐association is weaker than adenine self‐association. Steric factors, repulsive electrostatic forces and phosphate competitive reactivity with respect to chloride may explain the much higher pdA concentration needed to saturate the silver surface compared with A. Mg2+–phosphate complexation entails concentration‐dependent opposite effects on adenyl reactivity with (Ag)n+ sites. Cytosine, thymine and guanine base or corresponding nucleotides deliver weaker SER spectra and much higher SERS responses for chloride adsorption compared with A or pdA. This reveals a weaker adsorption of the oxo bases, assumed to result from alternative oxo and nitrogen interactions with the (Ag)n+ sites. Copyright © 2001 John Wiley & Sons, Ltd.
Surface‐enhanced Raman spectroscopic studies of 2‐mercaptobenzoxazole on silver sols
Authors: Bigotto Adriano , Pergolese Barbara
Published: August 2002

Surface‐enhanced Raman spectra of 2‐mercaptobenzoxazole (MBO) adsorbed on silver hydrosol were obtained. From the comparison of the SER and normal Raman spectra, both in the solid state and in NaOH solution, it can be deduced that the molecule is dissociatively adsorbed on the silver sol. The similarity between SER and normal Raman spectra of the corresponding silver complex is diagnostic of chemisorption of MBO on the metal surface. The SERS data were interpreted with the help of the results of RHF ab initio calculations both of the MBO anion, in which the 6–31 + G** basis set was used, and of the corresponding silver complex AgMBO, performed with the LANL2DZ basis set. On the basis of the description provided by the potential energy distribution of the vibrational normal modes related to the most enhanced bands in the SER spectra, it can be deduced that MBO interacts with the silver sol via the lone pairs of the sulphur and of the nitrogen atoms and, to some extent, also through the ring‐π system, assuming a tilted orientation with respect to the metal surface. Copyright © 2001 John Wiley & Sons, Ltd.