bluuebunny/crossref_metadata_2025 huggingface dataset:
Food-niche overlap between arctic and red foxes
Authors: Elmhagen Bodil , Tannerfeldt Magnus , Angerbjörn Anders
Published: October 2002

Arctic foxes (Alopex lagopus) in Fennoscandia have retreated to higher altitudes on the mountain tundra, possibly because of increased competition with red foxes (Vulpes vulpes) at lower altitudes. In this study we compare summer food niches of the two species in mountain tundra habitat. Arctic foxes consumed lemmings more often than red foxes did, while red foxes consumed field voles and birds more often. Yet despite substantial variation in the diet of each species among summers, food-niche overlaps between the species were consistently high in most summers, as arctic and red foxes responded similarly to temporal changes in prey availability. Occurrences of field voles and birds in fox scats were negatively correlated with altitude, while the occurrences of lemmings tended to increase with altitude. Since arctic foxes bred at higher altitudes than red foxes, the differences between arctic and red fox diets were better explained by altitudinal segregation than by differences between their fundamental food niches. Arctic foxes should therefore endeavour to use the more productive hunting grounds at the lower altitudes of their former range, but interference competition with red foxes might decrease their access to these areas, and consequently cause a decrease in the size of in their realised niche.
A NOVEL NUMERICAL APPROACH OF COMPUTING AMERICAN OPTION
Authors: SHU Jiwu , GU Yonggeng , ZHENG Weimin
Published: October 2002

It is well acknowledged that the European options can be valued by an analytic formula, but situation is quite different for the American options. Mathematically, the Black-Scholes model for the American option pricing is a free boundary problem of partial differential equation. This model is a non-linear problem; it has no closed form solution. Although approximate solutions may be obtained by some numerical methods, but the precision and stability are hard to control since they are largely affected by the singularity at the exercise boundary near expiration date. In this paper, we propose a new numerical method, namely SDA, to solve the pricing problem of the American options. Our new method combines the advantages of the Semi-analytical Method and the Sliced-fixed Boundary Finite Difference Method while overcomes demerits of the two. Using the SDA method, we can resolve the problems resulted from the singularity near the optimal exercise boundary. Numerical experiments show that the SDA method is more accurate and more stable than other numerical methods. In this paper, we focus on the American put options, but the proposed method is also applicable to other types of options.
ON THE DIFFERENT FORMS OF THE IBM–2 HAMILTONIAN
Authors: CANETTA E. , MAINO G.
Published: October 2002

An exhaustive picture of the different forms of the Hamiltonian of the Neutron-Proton Interacting Boson Model (IBM–2) is given. The existence of correlations between the most general forms of these Hamiltonians is clearly shown.
Kallistatin is a new inhibitor of angiogenesis and tumor growth
Authors: Miao Robert Q. , Agata Jun , Chao Lee , Chao Julie
Published: October 2002

Kallistatin is a unique serine proteinase inhibitor (serpin) and a heparin-binding protein. It has been localized in vascular smooth muscle cells and endothelial cells of human blood vessels, suggesting that kallistatin may be involved in the regulation of vascular function. Our previous study showed that kallistatin plays a role in neointima hyperplasia. In this study, we investigated the potential role of kallistatin in angiogenesis in vitro and in vivo. Purified human kallistatin significantly inhibited vascular endothelial growth factor (VEGF)– or basic fibroblast growth factor (bFGF)–induced proliferation, migration, and adhesion of cultured endothelial cells. Kallistatin attenuated VEGF- or bFGF-induced capillary density and hemoglobin content in subcutaneously implanted Matrigel plugs in mice. To further investigate the role of kallistatin in angiogenesis, we prepared adenovirus carrying the human kallistatin cDNA (Ad.HKBP) and evaluated the effect of kallistatin gene delivery on spontaneous angiogenesis in a rat model of hind-limb ischemia. Local kallistatin gene delivery significantly reduced capillary formation and regional blood perfusion recovery in the ischemic hind limb after removal of the femoral artery. Furthermore, a single intratumoral injection of Ad.HKBP into pre-established human breast tumor xenografts grown in athymic mice resulted in significant inhibition of tumor growth. CD31 immunostaining of tumor sections showed a decreased number of blood vessels in the kallistatin-treated group as compared to the control. These results demonstrate a novel role of kallistatin in the inhibition of angiogenesis and tumor growth.
Subtractive hybridization reveals the expression of immunoglobulinlike transcript 7, Eph-B1, granzyme B, and 3 novel transcripts in human plasmacytoid dendritic cells
Authors: Rissoan Marie-Clotilde , Duhen Thomas , Bridon Jean-Michel , Bendriss-Vermare Nathalie , Péronne Catherine , Vis Blandine de Saint , Brière Francine , Bates Elizabeth E. M.
Published: October 2002

Recent studies in humans have highlighted the importance of a distinct cellular entity, the plasmacytoid dendritic cell (PDC). To identify genes for which expression is restricted to human PDCs, a cDNA subtraction technique was applied using cDNA from activated monocyte-derived DCs (MDDCs) as competitor. In the 650 sequences analyzed, 25% were for B-cell transcripts. We also found lymphoid-related genes, immunoglobulinlike transcript 7 (ILT7), granzyme B (GrB), Spi-B, and the receptor tyrosine kinase Eph-B1. Granzyme B was up-regulated on activation, and protein was detected only in PDCs. Eph-B1 protein was expressed in the cytoplasm and the nuclei of PDCs and MDDCs, respectively. Interestingly, several novel molecules have been identified that were predicted to encode for a type 2 transmembrane protein (BRI3), a putative cytokine (C-15, a cysteine-rich–secreted protein), and a type 1 leucine-rich repeat protein (MAPA). The identification of genes expressed in PDCs provides new insights into their function and origin.
Combined effects of calcineurin inhibitors or sirolimus with anti-CD40L mAb on alloengraftment under nonmyeloablative conditions
Authors: Taylor Patricia A. , Lees Christopher J. , Wilson Jessica M. , Ehrhardt Michael J. , Campbell Matthew T. , Noelle Randolph J. , Blazar Bruce R.
Published: October 2002

The immunosuppressive drugs, cyclosporine A (CsA), tacrolimus, or sirolimus, were analyzed as single agents and in combination with anti-CD40L monoclonal antibody (mAb) for their effects on alloengraftment in mice conditioned with minimal total body irradiation (TBI). Whereas anti-CD40L mAb facilitated chimerism, neither sirolimus nor CsA resulted in substantial alloengraftment. However, sirolimus was synergistic with anti-CD40L mAb for inducing donor chimerism. Contrary to expectations, CsA, a T-cell receptor (TCR) signaling inhibitor, did not abrogate anti-CD40L mAb-facilitated engraftment but rather increased engraftment in anti-CD40L mAb-treated mice. Although tacrolimus alone or with anti-CD40L mAb resulted in similar levels of donor chimerism, donor T-cell reconstitution was very low in tacrolimus-treated mice. At 1 week after transplantation, CsA decreased thymic numbers more profoundly than sirolimus or tacrolimus in anti-CD40L mAb-treated recipients. In contrast, only sirolimus resulted in a decrease in host splenic T-cell numbers in anti-CD40L mAb-treated recipients. Importantly, sirolimus and anti-CD40L mAb induced profound donor tolerance with 100% acceptance of donor skin grafts placed early after bone marrow transplantation (BMT). In contrast, anti-CD40L mAb alone or in combination with CsA resulted in 12% or less donor skin graft acceptance early (1 month) and 60% or less later (3 months) after BMT. These data have clinical relevance and indicate that immunosuppressive pharmacologic agents enhance anti-CD40L mAb-facilitated alloengraftment and tolerance induction under nonmyeloablative conditioning.
Combined treatment with the checkpoint abrogator UCN-01 and MEK1/2 inhibitors potently induces apoptosis in drug-sensitive and -resistant myeloma cells through an IL-6–independent mechanism
Authors: Dai Yun , Landowski Terry H. , Rosen Steven T. , Dent Paul , Grant Steven
Published: October 2002

The effects of combined exposure to the checkpoint abrogator UCN-01 and pharmacologic MEK1/2 inhibitors were examined in human multiple myeloma (MM) cell lines. Treatment of RPMI8226, NCI-H929, and U266 MM cells with a minimally toxic concentration of UCN-01 (150 nM) for 24 hours resulted in mitogen-activated protein (MAP) kinase activation, an effect that was blocked by coadministration of the MEK1/2 inhibitor PD184352. These events were accompanied by enhanced activation of p34cdc2 and a marked increase in mitochondrial damage (loss of ΔΨm; cytochrome c and Smac/DIABLO (direct IAP binding protein with low pI) release), poly(ADP-ribose) polymerase (PARP) cleavage, and apoptosis. PD184352/UCN-01 also dramatically reduced clonogenic survival in each of the MM cell lines. In contrast to As203, apoptosis induced by PD184352/UCN-01 was not blocked by the free-radical scavenger n-acetyl-l-cysteine. Whereas exogenous interleukin 6 substantially prevented dexamethasone-induced lethality in MM cells, it was unable to protect them from PD184352/UCN-01–induced apoptosis despite enhancing Akt activation. Insulinlike growth factor 1 (IGF-1) also failed to diminish apoptosis induced by this drug regimen. MM cell lines selected for a high degree of resistance to doxorubicin, melphalan, or dexamethasone, or displaying resistance secondary to fibronectin-mediated adherence, remained fully sensitive to PD184352/UCN-01–induced cell death. Finally, primary CD138+ MM cells were also susceptible to UCN-01/MEK inhibitor-mediated apoptosis. Together, these findings suggest that simultaneous disruption of cell cycle and MEK/MAP kinase signaling pathways provides a potent stimulus for mitochondrial damage and apoptosis in MM cells, and also indicate that this strategy bypasses the block to cell death conferred by several other well-described resistance mechanisms.
Locus control regions
Authors: Li Qiliang , Peterson Kenneth R. , Fang Xiangdong , Stamatoyannopoulos George
Published: October 2002

Locus control regions (LCRs) are operationally defined by their ability to enhance the expression of linked genes to physiological levels in a tissue-specific and copy number–dependent manner at ectopic chromatin sites. Although their composition and locations relative to their cognate genes are different, LCRs have been described in a broad spectrum of mammalian gene systems, suggesting that they play an important role in the control of eukaryotic gene expression. The discovery of the LCR in the β-globin locus and the characterization of LCRs in other loci reinforces the concept that developmental and cell lineage–specific regulation of gene expression relies not on gene-proximal elements such as promoters, enhancers, and silencers exclusively, but also on long-range interactions of variouscis regulatory elements and dynamic chromatin alterations.
Echo-planar magnetic resonance imaging of Gaviscon alginate rafts in-vivo
Authors: Marciani Luca , Little Sarah L , Snee Janice , Coleman Nicholas S , Tyler Damian J , Sykes John , Jolliffe Ian G , Dettmar Peter W , Spiller Robin C , Gowland Penny A
Published: October 2002

Liquid Gaviscon and Gaviscon Advance are established reflux suppressant formulations. This study describes the use of echo-planar magnetic resonance imaging (EPI) to visualise non-invasively intragastric alginate rafts of Liquid Gaviscon and Gaviscon Advance in healthy subjects. Secondly, the feasibility of using relaxation rate (T2−1) measurements to monitor changes in the physicochemical properties of the rafts in-vivo is evaluated. Six subjects ingested 500 mL of a liquid meal and received a single dose of 20 mL Liquid Gaviscon or 10 mL Gaviscon Advance on 2 separate visits each and were imaged every 15 min. An alginate raft was observed in the stomach for all subjects and both treatments. The raft was observed to consist of a few large fragments on the majority of the scans for both products. At t = 60 min a raft was still present in all cases. Three-dimensional volume reconstructions showed, for the first time, the spatial distribution of the rafts within the gastric lumen. The T2−1 data showed potential for assessment of dynamic changes in the physicochemical properties of the alginate rafts in-vivo. We conclude that EPI shows great potential in assessing alginate rafts formation in-vivo.
In-vivo and in-vitro anti-inflammatory effect of Echinacea purpurea and Hypericum perforatum
Authors: Raso Giuseppina Mattace , Pacilio Maria , Di Carlo Giulia , Esposito Emanuela , Pinto Luisa , Meli Rosaria
Published: October 2002

Echinacea purpurea (L.) Moench and Hypericum perforatum (L.) were evaluated for their anti-inflammatory activity against carrageenan-induced paw oedema in mice. Each drug was administered orally to mice at 30 and 100 mg kg−1, twice daily. Only the higher dose significantly inhibited, time dependently, the formation of oedema, evaluated as area under the curve (echinacea P < 0.01; hypericum P < 0.05). Western blot analysis showed that in-vivo treatment with these extracts could modulate lipopolysaccharide (LPS) and interferon-γ induced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression in peritoneal macrophages. In particular, treatment with 100 mg kg−1 hypericum inhibited both iNOS and COX-2 expression, whereas treatment with 100 mg kg−1 echinacea down-regulated only COX-2 expression. The present study suggests that the anti-inflammatory effect of these extracts could be in part related to their modulation of COX-2 expression.
Amitriptyline has a dual effect on the conductive properties of the epithelial Na channel
Authors: Pena Florentina , Neaga Emil , Amuzescu Bogdan , Nitu Alina , Flonta Maria-Luisa
Published: October 2002

This study was undertaken with the aim of testing the action of amitriptyline on the epithelial Na channel (ENaC), which belongs to the same family (Deg/ENaC) as ASICs (acid-sensing ion channels) and many other putative members in the brain. We assumed that, having a common protein structure, characterization of the amitriptyline-ENaC interaction could help to elucidate the analgesic mechanism of this tricyclic antidepressant. Na-channel characteristics were derived from the analysis of blocker-induced lorentzian noise produced by amiloride. The effect of amitriptyline, present in the mucosal bathing solution, on the transepithelial short-circuit current (1sc) and conductance (Gt), and on the blocker-induced noise of apical Na channels, was studied on isolated ventral skin of the frog Rana ridibunda. Amitriptyline exerted a dual effect on the macroscopic short-circuit current and conductance of the epithelia, increasing these two parameters in the concentration range 0.1–50 μM, while at higher concentrations (100–1000 μM) it showed an inhibitory action. The decrease in the association rate (k01) of amiloride to the apical Na channels from 15.6 ± 4.2 μM−1 S−1 in control Cl-Ringer to 7.4 ± 1.7 μM−1 S−1 at 200 μM amitriptyline in a concentration-dependent manner suggests a competitive binding of amitriptyline to the pyrazine ring binding site for amiloride.
Evodia rutaecarpa protects against circulation failure and organ dysfunction in endotoxaemic rats through modulating nitric oxide release
Authors: Chiou Wen Fei , Ko Han Chieh , Chen Chieh Fu , Chou Cheng Jen
Published: October 2002

Using a rat model of septic shock we studied the effects of Evodia rutaecarpa, a Chinese herbal medicine with antimicrobial and anti-inflammatory activity, on haemodynamic parameters, biochemical markers of organ function and nitric oxide (NO) production. Anaesthetized rats challenged with a high dosage of endotoxin (Escherichia coli lipopolysaccharide; LPS; 50 mg kg−1, i.v.) for 6 h showed a severe decrease in mean arterial pressure. This was accompanied by delayed bradycardia, vascular hyporeactivity to phenylephrine and increase in plasma levels of lactate dehydrogenase, aspartate aminotransferase, bilirubin and creatinine, as well as NOx (NO−2 plus NO−3). Pretreatment with ethanol extract of E. rutaecarpa (25,50 and 100 mg kg−1, i.v.), 1 h before LPS, dose-dependently prevented the circulation failure, vascular hyporeactivity to phenylephrine, prevented liver dysfunction and reduced the NOx over-production in plasma in endotoxaemic rats. A selective inducible NO-synthase (iNOS) inhibitor, aminoguanidine (15 mg kg−1, i.v.), also effectively ameliorated the above pathophysiological phenomenon associated with endotoxaemia so that the normal condition was approached. Endotoxaemia for 6 h resulted in a significant increase in iNOS activity in the liver homogenate, which was attenuated significantly by E. rutaecarpa pretreatment. In summary, E. rutaecarpa, at the dosages used, exerted these beneficial effects probably through inhibition of iNOS activity and subsequent modulation of the release of NO. These significant results may offer E. rutaecarpa as a candidate for the treatment of this model of endotoxaemia.
Synthesis and Evaluation of Cationic Lipids Bearing Cholesteryl Groups for Gene Delivery In Vitro
Authors: Zhu Man-Zhou , Wu Qi-Hua , Zhang Guisheng , Ren Tan , Liu Dexi , Guo Qing-Xiang
Published: October 2002

A series of cationic lipids were designed and synthesized as vectors for gene delivery. The lipids contain a ketal moiety as a linker and a cholesteryl group as a hydrophobic tail. The framework of cholesteryl derivatives could increase the stability of liposomes by stabilizing the bilayers and their complexes with DNA to improve the transfection efficiency. The ketal bonds in lipids should easily degrade in an acidic environment in a cell (pH = 2–5) after transfection, resulting in little toxicity; in the neutral environment outside of cells (pH = 7), they should be stable as gene carriers. Gene transfer experiments in vitro with BL-6, 3LL, 293, 3T3, and Hela cells were performed. The results show that the gene transfection activity of three lipids is quite high, with least toxicity to cells under the experimental conditions.
SH-Group Introduction to the N-terminal of Subtilisin and Preparation of Immobilized and Dimeric Enzymes
Authors: Tada Tomoko , Mano Kazuhito , Yoshida Eri , Tanaka Naoki , Kunugi Shigeru
Published: October 2002

An SH group was introduced at the N-terminal of subtilisin Carlsberg by reacting with 2-iminothiolane·HCl (Traut reagent) in weakly basic media. The obtained subtilisin-SH was coupled with maleimide connected to an amine polymer (poly(allylamine); PAA), both in soluble and insoluble forms, or connected to the N-terminal of another subtilisin molecule. The immobilized subtilisins and subtilisin dimer thus obtained showed higher specificity towards proteineous substrates, although they had lower activities towards a tetrapeptide substrate. Subtilisins immobilized (conjugated) to PAA were more stable against autolytic and thermal disactivation than the intact enzyme.
Effect of Substitution on the Electrical Conductivity of LiMxMn2−xO4 (M = Cu, Mg, Zn)
Authors: Tomita Yasumasa , Yonekura Hiroshi , Kobayashi Kenkichiro
Published: October 2002

LiMxMn2−xO4 (M = Cu, Mg and Zn; x ≤ 0.5) was synthesized and the variance of the crystal structure and the electrical conductivity due to the substitution were studied. The crystal structure was changed by substitution, and the lattice constants decreased with x in LiZnxMn2−xO4. Both Zn and Li ions occupied tetrahedral sites. The Li–O bond became longer and Mn–O became shorter with increasing the content. The electrical conductivity for Mg and Zn compounds decreased from 10−4 S cm−1 to 10−7 S cm−1 with an increase in the Mg and Zn content. In the Cu compound, the conductivity was not changed very much. The infrared spectra for the Mg and Zn compounds shifted with x, indicating that the Mn–O bond became shorter and the Li–O bond longer with an increase in x. An XPS study showed a conversion of Mn3+ to Mn4+ with increasing the Mg, Zn or Cu content in these compounds.
Selective Transport of Heavy Metal Ions across a Cation-Exchange Membrane with a Chelating Agent in the Receiving Phase
Authors: Igawa Manabu , Narita Yohei , Okochi Hiroshi
Published: October 2002

Heavy metal ions can be selectively transported under the concentration gradient across a cation-exchange membrane with a chelating agent in the receiving phase. The selectivity depends on the complex formation constants of the ions with the agent. Metal ions are adsorbed into a cation-exchange membrane via the ion-exchange reaction and diffuse across the membrane. The desorption process is facilitated by the complexation in the receiving phase, which causes a large transport rate across the membrane. A transport equation was established and the theoretical values estimated by the equation and the permeation characteristics values obtained experimentally agreed well with the measured ion flux. The selectivity of the metal ions in the mixed solution is increased in the adequate concentration of the chelating agent in the receiving phase, when the chelate formation reaction may occur competitively between the ions with the agent in the receiving phase. The metal ions in the complex solution can be stripped as free ions across a cation-exchange membrane via the ion-exchange reaction with protons under a concentration gradient of acid.
Self-Assembly of Hexakis(4-pyridylmethoxy)cyclotriphosphazene and 1,4-Anthracenedicarboxylic Acid: Structure and Inclusion Behavior
Authors: Itaya Tomoyuki , Azuma Nagao , Inoue Kenzo
Published: October 2002

2,2,4,4,6,6-Hexakis(4-pyridylmethoxy)-2λ5,4λ5,6λ5,-cyclotriphosphazene (PyPN) and 1,4-anthracenedicarboxylic acid (DCA) formed polymeric supramolecules through hydrogen bonding between carboxyl and pyridyl groups. Two supramolecular self-assemblies were obtained: crystals 1 composed of PyPN/DCA = 1 : 2 from DMSO solution, and crystals 2 composed of PyPN/DCA = 1 : 3 from DMF solution. The former is monoclinic, space group P21/n with a = 12.419 Å, b = 24.10 Å, c = 20.794 Å, β = 93.53°, V = 6212 Å3, Z = 4. The X-ray analysis showed that the complementary hydrogen bonding occurs with two DCA molecules, one on each side of the phosphazene ring of PyPN, to give a novel assembly with polymeric structure. The self-assembly obtained from DMF solution seems to take a cylindrical structure composed of an alternating sequence of one PyPN and three DCA molecules and to be packed into a hexagonal arrangement, as suggested by X-ray diffraction data. These results and the inclusion behaviors of the solvent molecules into 1 and 2 are described.
The Crystal Structure and Tribology of a Novel Organic Crystalline Powder: the Mechanism of Lubricity
Authors: Nonomura Yoshimune , Kurita Kenkou , Kashimoto Akio , Hotta Hajime , Suzuki Toshiyuki , Kaneko Yohei , Iitaka Kazuhiro
Published: October 2002

A novel lubricant material, calcium N-lauroyl taurate (C11H23CONH(CH2)2SO3·0.5Ca, CaLT), has been synthesized and characterized. The powder of CaLT is a plate-shaped crystal with a lamellar structure. CaLT shows superior lubricity as a result of its unique internal and aggregate structure. When the CaLT powder is applied to an artificial skin, the frictional coefficient is favorably lower than that of other solid lubricants of similar type. The frictional coefficient of CaLT decreases rapidly at initial passage and becomes constant when CaLT is repeatedly rubbed onto an artificial skin. The high lubricity may result from disintegration of the powder aggregates, cleavage of the lamellar layers and deformation of the powder particles. This novel lubricant material, CaLT, will be a powerful ingredient of some cosmetic and/or personal-care products in the near future.
Evaluation of the Abbott IMxTM fluorescence polarization immunoassay and the Bio-Rad enzyme immunoassay for homocysteine: comparison with high-performance liquid chromatography
Authors: Donnelly James G , Pronovost Claire
Published: October 2002

We evaluated the precision, linearity and accuracy of the Abbott IMxTM and Bio-Rad (Axis) homocysteine assays. Both assays make use of S-adenosylhomocysteine hydrolase and excess adenosine, to convert homocysteine to S-adenosylhomocysteine (SAH). A monoclonal anti-SAH antibody is then used to quantify SAH. The IMx assay measures the fluorescence polarization of a conjugated SAH analogue for the final analytical step, whereas the Bio-Rad method uses a microplate enzyme immunoassay (EIA) employing an anti-mouse antibody-peroxidase conjugate. The Abbott procedure is completely automated whereas the Bio-Rad EIA is performed manually. Between-run coefficient of variation using commercial controls was 2·6% at 7 μmol/L, 2·5% at 13 μmol/L and 1·7% at 24 μmol/L for the Abbott method, and 19·7% at 6·4 μmol/L, 15·9% at 11·0 μmol/L and 14·5% at 23·4 μmol/L for the Bio-Rad method. Both assays correlated well with a high-performance liquid chromatography (HPLC) procedure for homocysteine: Bio-Rad EIA=1·03HPLC + 1·0 μmol/L, r=0·98, sy/x=0·51; Abbott IMx=1·02 HPLC + 0·7 μmol/L, r=0·99, sy/x=0·33. Both methods were linear up to 50 mol/L homocysteine. The IMx assay had superior precision as well as the technological advantage of being completely automated. Both immunoassays exhibited greatly improved throughput compared with our existing HPLC method.
Monitoring of carbamazepine and carbamazepine 10,11-epoxide in breast milk and plasma by high-performance liquid chromatography
Authors: Shimoyama Ritsuko , Ohkubo Tadashi , Sugawara Kazunobu
Published: October 2002

A high-performance liquid chromatographic method was developed for the measurement of carbamazepine (CBZ) and carbamazepine 10,11-epoxide (CBZE) in human breast milk and plasma. The method involves rapid C18 solid-phase extraction of CBZ and CBZE. Chromatographic separation was achieved with a reversed-phase C8 column using a mobile phase of potassium dihydrogenphosphate (pH 2·5) and acetonitrile (67:33 v/v), with ultraviolet detection at 254 nm. 2-Methyl CBZ was used as the internal standard. Determination of both CBZ and CBZE was possible in the range of 0·01 - 6·0 mg/L and 0·02 - 6·0 mg/L in milk and plasma, respectively. The recoveries of CBZ and CBZE added to the milk and plasma were 90·6 - 98.0% and 88·9 - 104·0%, respectively, with coefficients of variation less than 8·3% and 10·5%, respectively. The method has been used for drug level monitoring in milk and plasma samples obtained from CBZ-treated patients. The mean (SD) levels for CBZ in milk and plasma samples were 3·50 (0·4) mg/L and 6·18 (2·9) mg/L, and for CBZE were 1·28 (0·3) mg/L and 1·85 (1·0) mg/L, respectively. The mean (SD) milk/plasma ratios of CBZ and CBZE were 0·64 (0·2) and 0·79 (0·3), respectively. The milk/plasma ratio of CBZE was slightly higher than that of CBZ.
Effect of screening algorithm, parameter values and median smoothing on patient-specific risk estimates for Down's syndrome screening
Authors: Williams Karen L , Nix Barry A J , Dunstan Frank D J
Published: October 2002

The efficiency of a screening programme for Down's syndrome is usually expressed in terms of the detection rate for a given false positive rate. Two programmes with approximately equal detection rates and false positive rates would then be regarded as being broadly equivalent. While this might be the case at a population level, we show in this paper that it may be far from true at the individual patient level. Different algorithms, or even different implementations of the same algorithm can lead to calculation of very different individual risks and can result in different decisions for individual patients. Even though two programmes might lead to the same number of referrals, they could be referring quite different women. We consider the effect of using different parameter values within an algorithm, different algorithms and alternative ways of estimating the gestational age-dependent medians of the marker values. We show that the combined effects of these factors could explain much of the range of risks reported in the UK National External Quality Assessment Scheme for Down's syndrome screening.
Localization of oxidized HDL in atheromatous plaques and oxidized HDL binding sites on human aortic endothelial cells
Authors: Nakajima Takanori , Origuchi Nobuto , Matsunaga Toshiyuki , Kawai Shin-ichiroh , Hokari Shigeru , Nakamura Hiroaki , Inoue Ikuo , Katayama Shigehiro , Nagata Atsuo , Komoda Tsugikazu
Published: October 2002

We examined the localization of oxidized high-density lipoprotein (HDL) in atheromatous plaques and the oxidized HDL binding sites on endothelial cells. Histochemical analysis using CuSO4-oxidized HDL-specific 9F5-3a antibody indicated the presence of oxidized HDL in the intima of atheromatous plaques in human abdominal aortae. The cell surface binding of 125I-oxidized HDL to cultured human aortic endothelial cells (HAEC) was saturable, with an apparent dissociation constant ( Kd) of 1.43 μmol/L. Competition for 125I-oxidized HDL binding was strong for oxidized HDL, moderate for native HDL and low for acetylated low-density lipoprotein (LDL) or oxidized LDL. Using oxidized HDL as a ligand for blotting, a major 130-kDa band was detected in HAEC. These results suggest that oxidized HDL and its putative binding protein are present in atheromatous plaques and endothelial cells, respectively.
Hyperproinsulinaemia in elderly subjects: evidence for age-related pancreatic β-cell dysfunction
Authors: Gama R , Medina-Layachi N , Ranganath L , Hampton S , Morgan L , Marks V
Published: October 2002

SUMMARY. We investigated whether pancreatic pathogenesis of glucose intolerance in the elderly by comparing plasma glucose, immunoreactive insulin, C-peptide and proinsulin concentrations during a 100-g oral glucose load in six healthy older male volunteers [aged 69 (65·9-74·9) years; median (95% confidence limits)] and seven young male controls [aged 24·0 (21·9-26·3) years].

Fasting and integrated concentrations of glucose and C-peptide were similar in the elderly and young. Although fasting, insulin and proinsulin levels were similar, integrated insulin ( P=0·05) and proinsulin ( P< 0·05) concentrations were higher in the elderly than in controls. Insulin resistance, measured as homeostasis model assessment, was greater ( P< 0·05) in the elderly than in controls. Elderly men had greater molar ratios of integrated insulin:C-peptide ( P< 0·05) and proinsulin:Cpeptide ( P< 0·01) but their respective fasting molar ratios were similar when compared with controls.

Pancreatic β-cell secretion in older subjects, as assessed by C-peptide concentrations, was inappropriately low in the presence of insulin resistance. Their post-prandial 'hyperinsulinaemia' is probably due to a combination of hyperproinsulinaemia and reduced metabolic clearance of insulin. Older subjects had disproportionately high proinsulin to C-peptide levels, suggesting pancreatic β-cell dysfunction. These results are consistent with the notion that decreased insulin sensitivity and pancreatic β-cell dysfunction may predispose the elderly to glucose intolerance.
Quantitative and qualitative analysis of haemoglobin variants using capillary zone electrophoresis
Authors: Gerritsma J , Sinnige D , Drieze C , Sittrop B , Houtsma P , Ulshorst-Jansen N H , Huisman W
Published: October 2002

Capillary zone electrophoresis (CZE) has been introduced into the clinical chemistry laboratory because of its range of potential applications. In this paper, we evaluate an alkaline CZE method for the quantification of HbA 2 and HbF and also assess the combination of the alkaline CZE method with an acid CZE method for the determination of haemoglobin variants in an automated fashion. Correlation of the HbA2% determined between the HbA 2-CZE method (alkaline conditions) and the Helena Sickle Thal Quick Column® method was good ( r=0·91). The correlation between the HbF% determined by the HbA2-CZE method and by the alkaline denaturation method was acceptable ( r= 0·81). The HbA 2-CZE method was able to identify a large number of haemoglobin variants. The variants HbC and HbE or HbS and HbD, however, had the same characteristics under alkaline conditions and could therefore not be discriminated from each other. The identification of these overlapping variants could be accomplished by the analysis of the blood specimens in combination with the HbA1c-CZE method (acid conditions). We conclude that the presented applications for capillary zone electrophoresis can be used for quantitative and qualitative analysis of haemoglobin variants.
Gender differences in the urinary excretion rates of cortisol and androgen metabolites
Authors: Shamim Waqar , Yousufuddin Mohammed , Bakhai Ameet , Coats Andrew J S , Honour John W
Published: October 2002

Animal studies show significant differences in steroid metabolism between male and female subjects. Similar studies in human subjects are still needed. The aim of this study was to evaluate differences in 24-h urinary excretion of cortisol and androgen metabolites between healthy male and female volunteers to estimate if such differences were significant. Urinary metabolite measurements were performed by gas chromatography. The median urinary excretion of total cortisol metabolites was 6965 μg/day for men and 4595 μg/day for women ( P=0·0005). Urinary excretion of 11 β-hydroxyandrosterone, tetrahydrocortisone, tetrahydrocortisol (5 β), allotetrahydrocortisol (5 α), α-cortolone, β-cortolone + β-cortol and α-cortol were also significantly different in men compared with women. Total androgen metabolites in men (2660 μg/day) were also higher than in women (1850 μg/day) ( P< 0·0003). Similarly, urinary excretion of androsterone (5 α), aetiocholanolone (5 β) and dehydroepiandrosterone were also significantly greater (all P=0·01). This confirms significant differences in the steroid metabolite excretion profiles between men and women. Laboratories should consider adopting gender-related reference ranges for cortisol and androgen metabolite excretion in 24-h urine samples.
Adult reference ranges for serum cystatin C, creatinine and predicted creatinine clearance
Authors: Finney Hazel , Newman David J , Price Christopher P
Published: October 2002

Serum cystatin C measurement has been previously shown by ourselves and others to be a better indicator of changes in glomerular filtration rate (GFR) than serum creatinine. However, the available literature on reference values for cystatin C concentration remains surprisingly sparse; we thus set out to determine an adult reference range. Blood was taken from 309 healthy blood donors and creatinine and cystatin C concentrations were measured using commercially available automated methodologies. In addition, predicted creatinine clearances were calculated using the Cockcroft and Gault formula. The 95% reference intervals for creatinine, predicted creatinine clearance and cystatin C for all blood donors, regardless of gender, were 68-118 µmol/L, 58-120 ml/min/1·73 m 2 and 0·51-0·98 mg/L, respectively. For women, the intervals were 68-98 µmol/L, 60-119 ml/min/1·73 m 2 and 0·49-0·94 mg/ L; for men, they were 78-123 µmol/L, 57-122 ml/min/1·73 m 2 and 0·56-0·98 mg/L. The mean 95% reference interval for cystatin C in all donors under 50 years of age was 0·53-0·92 mg/L; for those over 50 years of age it was 0·58-1·02 mg/L. The small difference between male and female ranges meant that a single reference range for cystatin C could be established for all adults under 50 years of age without adjustment for body surface area. Serum cystatin C measurement offers a simpler and more sensitive screening test than serum creatinine for early changes in GFR.
Glomerular filtration rate by single-injection inulin clearance: definition of a workable protocol for children
Authors: Swinkels Dorine W , Hendriks Jan C. M. , Nauta Jeroen , de Jong Maria C. J. W.
Published: October 2002

The total serum clearance of inulin after a single intravenous injection is an established method for the determination of the glomerular filtration rate (GFR). To optimize this procedure in children, we analysed 117 serum inulin time-decay curves in 59 children (age range 1·3-15·2 years) with renal disease. It was found that the two-compartment model fitted statistically better to the disappearance curves of serum inulin than the one-compartment model. The sampling frequency could be reduced from 12 to a minimum of seven data points (t = 0, 10, 20, 30, 65, 120 and 240 min) in 4 h without a relevant change in the fit of the two-compartment model to the data or in the calculated clearance of serum inulin. We conclude that, by using a standardized 'seven-sample schedule', followed by a two-compartment analysis, the single-injection serum clearance of inulin is a suitable compromise between practical convenience and clinical accuracy for the determination of the GFR in children.
Insulin-like growth factor 1 measurement in diagnosis and management of acromegaly
Authors: Peacey Steven R , Shalet Stephen M
Published: October 2002

This article discusses the characteristic features of growth hormone secretion and insulin-like growth factor 1 (IGF-1) concentrations both in patients with acromegaly and in normal subjects. The therapeutic options for the treatment of acromegaly are briefly discussed, as are the current definitions of successful therapy. The article focuses on the use of serum and urinary growth hormone measurements along with the current and potential use of serum IGF-1, both at diagnosis and during long-term follow-up.
Drug interference in clinical chemistry: recommendation of drugs and their concentrations to be used in drug interference studies
Authors: Sonntag O , Scholer A
Published: October 2002

A group of international experts prepared two lists of drugs with their serum/plasma and urine concentrations, which should be used when evaluating the performance of a new laboratory method. The two lists were verified by running in vitro interference studies in three European laboratories on Hitachi instruments. The study identified the following new interferants: acid phosphatase in serum by ibuprofen and theophylline; non-prostatic acid phosphatase in serum by cefoxitin and doxycycline; creatine kinase MB in serum by doxycycline; total bilirubin in serum (Jendrassik-Grof method) by rifampicin and intralipid; total bilirubin in serum (DPD method) by intralipid; creatinine in serum (Jaffe method) by cefoxitin; fructosamine in serum by levodopa and methyldopa; uric acid in serum by levodopa, methyldopa and tetracycline; carbamazepine in serum by doxycycline, levodopa, methyldopa and metronidazole; digitoxin in serum by rifampcin; phenytoin in serum by doxycycline, ibuprofen, metronidazole and theophylline; theophylline in serum by acetaminophen, cefoxitin, doxycycline, levodopa, phenylbutazone and rifampicin; tobramycin in serum by cefoxitin, doxycycline, levodopa, rifampicin and phenylbutazone; valproic acid in serum by phenylbutazone; C3 in serum by intralipid; C4 in serum by doxycycline; rheumatoid factor in serum by ibuprofen and metronidazole; pancreatic amylase and total amylase in urine by acetylcysteine, ascorbic acid, cefoxitin, gentamicin, levodopa, methyldopa and ofloxacin; magnesium in urine by acetylcysteine, gentamicin and methyldopa; β2-microglobulin in urine by ascorbic acid; total protein in urine by ascorbic acid, Ca-dobesilate and phenylbutazone.

Interference in acid phosphatase, creatine kinase MB and bilirubin methods was observed at very low analyte concentrations, and therefore it may not be evident at higher concentrations. The study confirmed the usefulness of the recommendation.
Which surrogate marker can be used to assess the effectiveness of the laboratory and its contribution to clinical outcome?
Authors: Waise A , Plebani M
Published: October 2002

Assessment of the effectiveness of the clinical laboratory and its contribution to outcomes is gaining increasing emphasis, as part of the overall attempts at making clinical services more transparent and accountable. Tools traditionally used in the assessment of laboratory effectiveness and efficiency have included laboratory accreditation, Q-probes, performance in quality assurance programmes and staffing and cost issues. There is, however, a need to introduce different measures that highlight the laboratory efficiency and contribution to clinical effectiveness and outcomes. Such measures should, ideally, be quantifiable and evidence-based. The use of markers of efficiency and effectiveness could be used as tools to aid this process. Such markers could include incident reporting, the appropriateness of assay repertoire, adding value to reports, the quality of comments made, provision of information on the effect of analytical and biological variation on results, cascading requests to help making diagnoses and unearthing such diagnoses. We suggest that these measures contribute towards the implementation of the clinical governance agenda in relation to the laboratory, and could be used as indicators in laboratory accreditation.
In vitro cold activation of complement shown by an overestimation of total complement 4: a study in patients with hepatitis C virus infection
Authors: Maguire O C , Curry M P , O'Gorman P , Parfrey N , Hegarty J , Cunningham S K
Published: October 2002

Total complement 4 (C4) levels, when analysed on the Beckman Array nephelometer, were found to increase in a number of serum specimens [predominantly from patients with hepatitis C virus (HCV) infection] after overnight storage at 4°C. In order to investigate whether the phenomenon of in vitro cold- dependent activation of complement (CDAC) was the explanation for this increase, paired specimens were collected from 63 patients with HCV infection in tubes with no anticoagulant (serum) and in tubes containing EDTA (which inhibits complement activation). C4 levels increased after overnight storage at 4°C in 33 serum specimens (52%). In contrast, no increase in C4 levels was observed in any of the 63 EDTA specimens. Immunofixation of intact and activated C4 products confirmed that complement activation had taken place in the serum specimens in which C4 levels had increased after storage. There was a higher frequency of hepatitis C viraemia ( P< 0·0001), HCV antibody positivity ( P< 0·05) and the presence of rheumatoid factor ( P< 0·05) in the group of patients in whose serum samples CDAC had occurred ( n=33) than in the other group ( n= 30). As a result of our findings on C4 analysis in stored serum specimens, we would recommend potassium EDTA plasma as the specimen of choice for complement analysis on the Beckman Array.
Protection by metal complexes with SOD-mimetic activity against oxidative gastric injury induced by indometacin and ethanol in rats
Authors: El-Missiry M A , El-Sayed I H , Othman A I
Published: October 2002

We have investigated the protective effect of oral administration of copper and manganese complexes with superoxide dismutase (SOD)-mimetic activity against oxidative gastric mucosal injury induced by the non-steroidal anti-inflammatory drug indometacin with ethanol in the rat. The total area of the gastric lesions and lipid peroxidation were significantly increased 1 h after oral administration of indometacin (15 mg/kg) and ethanol, indicating an acute oxidative injury. The activities of SOD, catalase (CAT), glutathione-S-transferase (GST) and glutathione content were significantly decreased in the gastric mucosa by indometacin plus ethanol. Manganese or copper complexes showed SOD-mimetic activity. Pretreatment with these complexes protected against gastric mucosal lesions and decreased lipid peroxides, as well as attenuating the decrease in the activities of SOD, CAT and GST in gastric mucosa. These findings suggest that active oxygen species and lipid peroxidation play an important role in the pathogenesis of gastric mucosal injury induced by indometacin. In addition, we have shown that Mn and Cu complexes have gastroprotective properties against ulceration induced by indometacin plus ethanol. The present results suggest that appropriate copper or manganese complex supplementation may potentially provide prophylaxis or therapy for some pathologies associated with excessive free radical production and inhibited SOD activity.
Identification and determination of salicylic acid and salicyluric acid in urine of people not taking salicylate drugs
Authors: Baxter G. J. , Lawrence J. R. , Graham A. B. , Wiles D , Paterson J. R.
Published: October 2002

Background Salicylic acid (SA) is present in the serum of people who have not taken salicylate drugs. Now we have examined the urine of these subjects and found that it contains SA and salicyluric acid (SU). We have established the identities of these phenolic acids and determined their concentrations. Methods and Results The acidic hydrophobic compounds of urine were separated using high-performance liquid chromatography (HPLC) and were detected and quantified electrochemically. Two approaches were used to establish the identity of SA and SU. First, the retention times (Rt) of the substances extracted and those of SA and SU were compared under two sets of chromatographic conditions; the Rt of the compounds suspected to be SA and SU and those of the authentic substances were very similar under both sets of conditions. Second, the unknown substances, isolated by HPLC, were treated with acetyl chloride in methanol and compared with the methyl esters of SA and SU by using gas chromatography-mass spectrometry; the unknown compounds after esterification had very similar mass spectra and gas chromatographic Rt to those of methyl salicylate and methyl salicylurate. The median ( n = 10) urinary concentration of SA was 0·56 μmol/L (range 0·07-0·89 μmol/L) and that of SU was 3·20 μmol/L (range 1·32-6·54 μmol/L). SA and its major urinary metabolite, SU, were found in the urine of all of the 10 people examined.
Cystatin C
Authors: Newman David J
Published: October 2002

Clinical biochemists have long known the analytical and clinical limitations of creatinine and creatinine clearance measurement in the assessment of glomerular filtration rate (GFR). This background is reviewed in the article before assessing the utility of cystatin C, the most promising replacement biochemical marker yet identified. Cystatin C has been used in clinical research studies for more than 20 years and yet has been introduced into clinical practice in very few centres, firstly in Lund in Sweden and now Carshalton in the UK. Why is this? The review compares our ability to measure creatinine and cystatin C and their relative sensitivity and specificity for changes in GFR. Comparison is made of cystatin C with creatinine as screening tests for early renal dysfunction and for monitoring its progression where issues of reference ranges and within-individual variation are important. The superiority of cystatin C as a screening test is probably accepted but there are still concerns about non-renal influences upon its circulating concentration, particularly steroid therapy, insufficient data on the influence of malignancy and a general lack of prospective clinical studies confirming the prognostic significance of cystatin C.