bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrospray ionization mass spectrometric studies on the amphoteric surfactant cocamidopropylbetaine
Authors: Eichhorn Peter , Knepper Thomas P. 
Published: August 2002

AbstractAfter liquid chromatographic (LC) separation, electrospray ionization mass spectrometry (ESI‐MS) was investigated for the determination of the amphoteric surfactant cocamidopropylbetaine (CAPB). In the positive ion mode the molecule formed the adduct ions [M + H]+, [M + Na]+and [M + K]+. Adducts of these cations were also detected with decreasing abundance as dimer and trimer clusters. Additionally, doubly charged molecular ions with different combinations of cations were identified. It was noticed that the relative abundances of individual cation adducts were not reproducible, apparently owing to varying contents of alkali metal ions originating from the solvent and the sample. Under negative ionization, the major molecular ion was [M − H]−. Higher clusters formed by two and three surfactant molecules, i.e. [2M − H]−and [3M − H]−were likewise registered. The tendency to form clusters in both positive and negative ion modes, even at 0.1 mg l−1levels, was attributed to strong electrostatic interactions between the zwitterionic head groups. Further evidence for this assumption was provided by the detection of a fragment formed from [2M − H]−which contained the two charged head groups. Studies were undertaken in the negative ion mode on the concentration‐ and orifice voltage‐dependent monomer, dimer and trimer formation of C12‐CAPB in order to evaluate potential issues in using the ion [M − H]−mode for quantitative analysis. Finally, the established (−)‐LC/ESI‐MS method was applied to follow up the primary degradation of CAPB in a laboratory‐scale fixed‐bed bioreactor (FBBR) spiked with a test concentration of 10 mg l−1. Direct analysis without sample pretreatment revealed that higher alkyl homologues were more prone to adsorption. Primary biodegradation of all alkyl homologues was completed after a period of 4 days. Selected lyophilized FBBR samples were examined for the presence of transient or stable degradation intermediates, but no metabolite could be identified. Copyright © 2001 John Wiley & Sons, Ltd.
Quantification of nimesulide in human plasma by high‐performance liquid chromatography/tandem mass spectrometry. Application to bioequivalence studies
Authors: Barrientos‐Astigarraga Rafael Eliseo , Vannuchi Yuri Borges , Sucupira Mauro , Moreno Ronilson Agnaldo , Muscará Marcelo Nicolás , Nucci Gilberto De 
Published: August 2002

AbstractA method based on liquid chromatography with negative ion electrospray ionization and tandem mass spectrometry is described for the determination of nimesulide in human plasma. Liquid–liquid extraction using a mixture of diethyl ether and dichloromethane was employed and celecoxib was used as an internal standard. The chromatographic run time was 4.5 min and the weighted (1/x) calibration curve was linear in the range 10.0–2000 ng ml−1. The limit of quantification was 10 ng ml−1, the intra‐batch precision was 6.3, 2.1 and 2.1% and the intra‐batch accuracy was 3.2, 0.3 and 0.1% for 30, 300 and 1200 ng ml−1 respectively. The inter‐batch precision was 2.3, 2.8 and 2.7% and the accuracy was 3.3, 0.3 and 0.1% for 30, 300 and 1200 ng ml−1 respectively. This method was employed in a bioequivalence study of one nimesulide drop formulation (nimesulide 50 mg ml−1 drop, Medley S/A Indústria Farmacêutica, Brazil) against one standard nimesulide drop formulation (Nisulid, 50 mg ml−1 drop, Astra Médica, Brazil). Twenty‐four healthy volunteers (both sexes) took part in the study and received a single oral dose of nimesulide (100 mg, equivalent to 2 ml of either formulation) in an open, randomized, two‐period crossover way, with a 2‐week washout interval between periods. The 90% confidence interval (CI) for geometric mean ratios between nimesulide and Nisulid were 93.1–109.6% for Cmax, 87.7–99.8% for AUClast and 88.1–99.7% for AUC0–∞. Since the 90% CI for the above‐mentioned parameters were included in the 80–125% interval proposed by the US Food and Drug Administration, the two formulations were considered bioequivalent in terms of both rate and extent of absorption. Copyright © 2001 John Wiley & Sons, Ltd.
Real‐time PCR for detection and quantitation of hepatitis B virus DNA
Authors: Chen Ren Wei , Piiparinen Heli , Seppänen Mikko , Koskela Pentti , Sarna Seppo , Lappalainen Maija 
Published: August 2002

AbstractA sensitive and reproducible real‐time PCR assay based on TaqMan technology was developed for the detection and quantitation of hepatitis B virus (HBV) DNA in serum, and compared with an “in‐house” qualitative PCR assay. HBV DNA was measured in 125 serum samples from 76 hepatitis B patients, consisting of 22 patients with an acute infection, 20 patients with a previous history of hepatitis B infection, and 34 patients with a chronic hepatitis B. Four patients with a chronic infection were treated with either an IFN‐alpha monotherapy or a combination of IFN‐alpha and lamivudine. Twenty‐nine sera from healthy individuals and non‐hepatitis B patients served as negative controls. The assay was validated by using a 10‐fold dilution series of the World Virological Quality Control (VQC) sample containing 3.73 × 107 genome equivalents per ml. The detection limit for the real‐time PCR was 3.73 × 102 genome equivalents per ml (geq/ml), while it was 3.73 × 103 geq/ml for the in‐house PCR. The real‐time PCR assay had an 8‐logarithm dynamic range spanning from 102 to 1010 geq/ml. In clinical serum samples, the real‐time PCR and the in‐house PCR detected HBV DNA in 81% (101/125) and 66% (83/125) of samples, respectively. HBV DNA was not detected among the negative controls by either of these assays. In conclusion, real‐time PCR is a sensitive, specific, and a reproducible approach for the detection and quantitation of HBV DNA in clinical serum samples, useful also for monitoring the efficacy of antiviral treatment. J. Med. Virol. 65:250–256, 2001. © 2001 Wiley‐Liss, Inc.
Molecular epidemiology of calicivirus infections in Norway
Authors: Vainio Kirsti , Stene‐Johansen Kathrine , Jonassen Tom Øystein , Bruu Anne‐Lise , Grinde Bjørn 
Published: August 2002

AbstractThe national reference laboratory for calicivirus diagnostics monitors the epidemiology of calicivirus infections in Norway. During winter 1998‐1999, 406 fecal samples were received from patients with suspected calicivirus infection. Of these, 76 (19%) were calicivirus positive by a nested reverse transcription‐polymerase chain reaction. A number of alternative PCR designs were employed to disclose false negatives, but none were found. One half of the PCR positive samples were sequenced in order to investigate whether various cases represented the same outbreak, and to what extent a single or multiple subtypes were responsible for the morbidity during this season. The sequence data revealed that the majority of cases represented a genotype related to the Lordsdale strain, whereas the remaining cases seemed more sporadic. Most often, samples from particular outbreaks were highly homogenous. However, in a few cases, samples connected with the same outbreak proved to contain epidemiologically independent strains. J. Med. Virol. 65:309–314, 2001. © 2001 Wiley‐Liss, Inc.
HTLV‐II infection associated with a chronic neurodegenerative disease: Clinical and molecular analysis
Authors: Silva Edimilson A. , Otsuki Koko , Leite Ana Claudia B. , Alamy Alexandre H. , Sá‐Carvalho Daniel , Vicente Ana Carolina P. 
Published: August 2002

AbstractHTLV II is a retrovirus endemic in some Amerindian tribes and spread worldwide with a high prevalence among intravenous drug abusers. It has three different genetic subtypes a, b, and d, defined mainly by the long terminal repeat (LTR) region. HTLV II has been associated with a neurodegenerative disease in few cases. We describe the first well‐documented case in Brazil where the virus is endemic in isolated ethnic groups. The patient is a 55‐year‐old woman with a chronic and painful syndrome characterized by spastic paraparesis, hyperactive reflexes and spastic bladder. Somatosensory evoked potential indicates a thoracic spinal cord lesion. Computer tomography showed periventricular demyelination. Enzyme‐linked immunosorbent assay was positive for HTLV I/II whereas the discriminatory Western blot was indeterminate. Molecular analysis of the Tax region revealed a HTLV II pattern that was also confirmed through sequencing the LTR region. Phylogenetic analysis of the LTR sequence shows an HTLV IIa subtype that clustered with the virus isolated from Kayapo Indians and Brazilian urban intravenous drug users. Indeterminate Western blots are frequently found using commercial kits, therefore we recommend that all cases in which a myelopathy is associated with an indeterminate serological result should be evaluated by PCR to determine the actual number of HTLV II associated myelopathy cases. J. Med. Virol. 66:253–257, 2002. © 2002 Wiley‐Liss, Inc.
Risk factors and mechanism of transplacental transmission of hepatitis B virus: A case‐control study
Authors: Xu De‐Zhong , Yan Yong‐Ping , Choi Bernard C.K. , Xu Jian‐Qiu , Men Ke , Zhang Jing‐Xia , Liu Zhi‐Hua , Wang Fu‐Sheng 
Published: August 2002

AbstractIntrauterine hepatitis B virus (HBV) infection has been suggested to be caused by transplacental transmission that cannot be blocked by hepatitis B vaccine. This would decrease the effectiveness of hepatitis B vaccine. This study examined the risk factors and mechanism of transplacental HBV transmission. A case‐control study included 402 newborn infants from 402 HBsAg‐positive pregnant women. Among these, 15 newborn infants infected with HBV by intrauterine transmission were selected as cases, and the rest as controls. A pathology study included 101 full‐term placentas from the HBsAg‐positive pregnant women above and 14 from HBsAg‐negative pregnant women. Immunohistochemistry staining and HBV DNA in situ hybridization were used to estimate the association of intrauterine HBV infection and HBV infection in the placentas. HBeAg positivity in mothers' sera (OR = 17.07, 95%CI 3.39–86.01) and threatened preterm labor (OR = 5.44, 95%CI 1.15–25.67) were found to be associated with transplacental HBV transmission. The intrauterine infection rate increased linearly and significantly with maternal serum HBsAg titers (trend test P = 0.0117) and HBV DNA concentration (trend test P < 0.01). Results of the pathology study showed that HBV infection rates decreased gradually from the maternal side to the fetal side (trend test P = 0.0009) in the placental cell layers. There was a significant association between intrauterine HBV transmission and HBV infection in villous capillary endothelial cells (VCEC) in the placenta (OR = 18.46, P = 0.0002). The main risk factors for intrauterine HBV infection are maternal serum HBeAg positivity, history of threatened preterm labor, and HBV in the placenta especially the villous capillary endothelial cells. Previous reports of transplacental leakage of maternal blood causing intrauterine infection are confirmed. In addition, there appears to be a “cellular transfer” of HBV from cell to cell in the placenta causing intrauterine infection. This latter hypothesis needs to be confirmed. J. Med. Virol. 67:20–26, 2002. © 2002 Wiley‐Liss, Inc.
Human cytomegalovirus as a direct pathogen: Correlation of multiorgan involvement and cell distribution with clinical and pathological findings in a case of congenital inclusion disease
Authors: Bissinger A.L. , Sinzger C. , Kaiserling E. , Jahn G. 
Published: August 2002

AbstractThe human cytomegalovirus (HCMV), a member of the Herpesviridae, is the most frequent cause of congenital virus infections and a major cause of morbidity and mortality in immunocompromised patients. Due to the lack of an appropriate animal model, insight into the pathogenesis of HCMV infections originates primarily from in situ examination of HCMV‐infected tissues. Although in immunocompromised adults such tests are complicated frequently by the presence of additional misleading pathogens, the absence of additional pathogens renders congenital inclusion disease the most suitable access for investigation of pathogenetic aspects of HCMV infections. Immunohistochemical examination of tissue sections from a boy with fatal congenital inclusion disease was undertaken to detect the extent of multiorgan and cell involvement. Adrenal gland, bone marrow, diencephalon, heart, kidney, liver, lung, pancreas, placenta, small bowel and spleen were included in this study. Detection of virus antigens from different phases of viral replication revealed that all investigated organs were infected by HCMV. Simultaneous detection of cell type specific marker molecules showed that a variety of cell types stained positive for HCMV antigens including endothelial cells, epithelial cells, smooth muscle cells, mesenchymal cells, hepatocytes, monocytes/macrophages and granulocytes. The lung, the pancreas, the kidneys and the liver were the major target organs with a high number of HCMV infected cells. This correlated with multiorgan failure as the cause of death and strongly indicates direct pathogenetic effects of HCMV. J. Med. Virol. 67:200–206, 2002. © 2002 Wiley‐Liss, Inc.
Reduced phospholipase C‐β activity and isoform expression in the cerebellum of TS65DN mouse: A model of down syndrome
Authors: Ruiz de Azúa Iñigo , Lumbreras María Ángeles , Zalduegui Amaia , Baamonde Carmela , Dierssen Mara , Flórez Jesús , Sallés Joan 
Published: August 2002

AbstractAgonist‐ and guanine‐nucleotide‐stimulated phospholipase C‐β (PLC) activity was characterized in crude plasma membrane preparations from cerebral cortex, hippocampus and cerebellum of Ts65Dn mice, a model for Down syndrome, and their control littermates. The levels of expression of PLC‐β(1–4) isoforms and G‐protein αq/11 subunits were also quantified by Western blot analysis to establish their contribution to the patterns of PLC functioning. PLC activity regulated by G‐proteins and muscarinic and 5‐HT2 receptors presented a regional distribution in both control and Ts65Dn mice. In both groups of mice, the intensity of PLC responses to maximal activation by calcium followed the sequence cerebellum > cortex > hippocampus. Both basal and maximal PLC activities, however, were significantly lower in cerebellar membranes of Ts65Dn than in control mice. This difference was mostly revealed in crude plasma membranes prepared from cerebellum at the level of G‐protein‐dependent‐PLC activity because the concentration‐response curve to GTPγS showed a reduction of the maximal effect in Ts65Dn mice, with no change in sensitivity (EC50). Western blot analysis showed a heterogeneous distribution of PLC‐β(1–4) isoforms in both groups of mice. The levels of PLC‐β4 isoform, however, were significantly lower in the cerebellum of Ts65Dn than in control mice. We conclude that the cerebellum of Ts65Dn mice has severe deficiencies in PLC activity stimulated by guanine nucleotides, which are specifically related to a lower level of expression of the PLC‐β4 isoform, a fact that may account for the neurological phenotype observed in this murine model of Down syndrome. J. Neurosci. Res. 66:540–550, 2001. © 2001 Wiley‐Liss, Inc.
Glutamine transport in C6 glioma cells: Substrate specificity and modulation in a glutamine deprived culture medium
Authors: Dolińska Monika , Dybel Anna , Hilgier Wojciech , Zielińska Magdalena , Zabłocka Barbara , Bużańska Leonora , Albrecht Jan 
Published: August 2002

AbstractA previous study has shown that glutamine (Gln) uptake in C6 cells grown in a standard medium containing 2 mM Gln, is predominantly mediated by a sodium‐dependent system that is inhibited by ASC system substrates alanine (Ala), serine (Ser), cysteine (Cys) and threonine (Thr), shows pH sensitivity and partial tolerance to substitution of Na+by Li+, features compatible with system ASCT2 that is strongly expressed in cultured astrocytes. The uptake was not inhibited by the model system A substrate α‐(methylamino)isobutyric acid (MeAiB), and glycine (Gly) or proline (Pro), indicating that the substrate‐regulated system A as defined by routine criteria is relatively inactive in these cells (Dolińska et al.,2000). In this study we compared the uptake of radiolabeled Gln and a model ASC substrate ‐Thr in cells grown to the same density in Gln‐containing and Gln‐deprived media. Cells grown in the absence of Gln showed a reduced activity of system ASC‐mediated Gln uptake, and the system lost tolerance for Li+and became somewhat more resistant to lowering pH of the medium. In contrast to cultured astrocytes deprived of Gln, the overall Gln uptake activity in C6 cells adapted to grow in a medium without Gln was lower than in cells grown in a Gln containing medium, and the uptake by system A remained inactive. C6 cells cultured both in the presence and absence of Gln expressed ASCT2 mRNA, indicating that system ASCT2‐mediated Gln uptake is modulated at a posttranscriptional level. In contrast to Gln uptake, Thr uptake was more active in cells cultured in the absence of Gln and showed neither pH dependence nor lithium tolerance in either medium, which is typical of an uptake mediated by the widespread ASCT1 isoform of system ASC. In C6 cells grown in the presence or absence of Gln alike, ≈20% of the sodium‐dependent Gln uptake was resistant to MeAiB+Thr, indicating contribution of system N. The N system‐mediated uptake in C6 cells grown in the absence, but not in the presence of Gln was not inhibited by glutamate (Glu) that conforms to the characteristics of the glial N system variant, SN1. © 2001 Wiley‐Liss, Inc.
Intracellular compartmentation of pyruvate in primary cultures of cortical neurons as detected by 13C NMR spectroscopy with multiple 13C labels
Authors: Cruz Fátima , Villalba Martín , García‐Espinosa María A. , Ballesteros Paloma , Bogónez Elena , Satrústegui Jorgina , Cerdán Sebastián 
Published: August 2002

AbstractThe intracellular compartmentation of pyruvate in primary cultures of cortical neurons was investigated by high resolution 13C NMR using mixtures of different pyruvate precursors conveniently labeled with 13C or unlabeled. Cells were incubated with 1–5 mM (1‐13C, 1,2‐13C2 or U‐13C6) glucose only or with mixtures containing 1.5 mM (1‐13C or U‐13C6) glucose, 0.25–2.5 mM (2‐13C or 3‐13C) pyruvate and 1 mM malate. Extracts from cells and incubation media were analyzed by 13C NMR to determine the relative contributions of the different precursors to the intracellular pyruvate pool. When (13C) glucose was used as the sole substrate fractional 13C enrichments and 13C isotopomer populations in lactate and glutamate carbons were compatible with a unique intracellular pool of pyruvate. When mixtures of (13C) glucose, (13C) pyruvate and malate were used, however, the fractional 13C enrichments of the C2 and C3 carbons of lactate were higher than those of the C2 and C3 carbons of alanine and depicted a different 13C isotopomer distribution. Moreover, neurons incubated with 1 mM (1,2‐13C2) glucose and 0.25–5 mM (3‐13C) pyruvate produced exclusively (3‐13C) lactate, revealing that extracellular pyruvate is the unique precursor of lactate under these conditions. These results reveal the presence of two different pools of intracellular pyruvate; one derived from extracellular pyruvate, used mainly for lactate and alanine production and one derived from glucose used primarily for oxidation. A red‐ox switch using the cytosolic NAD+/NADH ratio is proposed to modulate glycolytic flux, controlling which one of the two pyruvate pools is metabolized in the tricarboxylic acid cycle when substrates more oxidized or reduced than glucose are used. © 2001 Wiley‐Liss, Inc.
Metabolic changes in quinolinic acid‐lesioned rat striatum detected non‐invasively by in vivo 1H NMR spectroscopy
Authors: Tkáč Ivan , Keene C. Dirk , Pfeuffer Josef , Low Walter C. , Gruetter Rolf 
Published: August 2002

AbstractIntrastriatal injection of quinolinic acid (QA) provides an animal model of Huntington disease. In vivo 1H NMR spectroscopy was used to measure the neurochemical profile non‐invasively in seven animals 5 days after unilateral injection of 150 nmol of QA. Concentration changes of 16 metabolites were measured from 22 μl volume at 9.4 T. The increase of glutamine ((+25 ± 14)%, mean ± SD, n = 7) and decrease of glutamate (−12 ± 5)%, N‐acetylaspartate (−17 ± 6)%, taurine (−14 ± 6)% and total creatine (−9 ± 3%) were discernible in each individual animal (P < 0.005, paired t‐test). Metabolite concentrations in control striata were in excellent agreement with biochemical literature. The change in glutamate plus glutamine was not significant, implying a shift in the glutamate‐glutamine interconversion, consistent with a metabolic defect at the level of neuronal‐glial metabolic trafficking. The most significant indicator of the lesion, however, were the changes in glutathione ((−19 ± 9)%, P < 0.002)), consistent with oxidative stress. From a comparison with biochemical literature we conclude that high‐resolution in vivo 1H NMR spectroscopy accurately reflects the neurochemical changes induced by a relatively modest dose of QA, which permits one to longitudinally follow mitochondrial function, oxidative stress and glial‐neuronal metabolic trafficking as well as the effects of treatment in this model of Huntington disease. © 2001 Wiley‐Liss, Inc.
NF‐κB and IκBα expression following traumatic brain injury to the immature rat brain
Authors: Sanz Olga , Acarin Laia , González Berta , Castellano Bernardo 
Published: August 2002

AbstractNF‐κB is one of the most important modulators of stress and inflammatory gene expression in the nervous system. In the adult brain, NF‐κB upregulation has been demonstrated in neurons and glial cells in response to experimental injury and neuropathological disorders, where it has been related to both neurodegenerative and neuroprotective activities. Accordingly, the aim of this study was to evaluate the cellular and temporal patterns of NF‐κB activation and the expression of its endogenous inhibitor IκBα following traumatic brain injury (TBI) during the early postnatal weeks, when the brain presents elevated levels of plasticity and neuroprotection. Our results showed that cortical trauma to the 9‐day‐old rat brain induced a very fast upregulation of NF‐κB, which was maximal within the first 24 hours after injury. NF‐κB was mainly observed in neuronal cells of the degenerating cortex as well as in astrocytes located in the corpus callosum adjacent to the injury, where a pulse‐like pattern of microglial NF‐κB activation was also found. In addition, astrocytes of the corpus callosum, and microglial cells to a lower extent, also showed de novo expression of IκBα within the time of NF‐κB activation. This study suggests an important role of NF‐κB activation in the early mechanisms of neuronal death or survival, as well as in the development of the glial and inflammatory responses following traumatic injury to the immature rat brain. © 2002 Wiley‐Liss, Inc.