bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of urinary free cortisol by tandem mass spectrometry and comparison with results obtained by gas chromatography-mass spectrometry and two commercial immunoassays
Authors: Wood Lisa , Ducroq David H , Fraser Helen L , Gillingwater Scott , Evans Carol , Pickett Alan J , Rees Derek W , John Rhys , Turkes Atilla 
Published: June 2008

Background Determination of urinary free cortisol (UFC) is an important adjunct for the assessment of adrenal function. In this study, we have analysed cortisol concentrations in urine samples by gas chromatography-mass spectrometry (GC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and two immunoassays. The results were compared with GC-MS. The interference of cortisol ring-A metabolites in immunoassays was also assessed. Methods The GC-MS technique involved solvent extraction, LH-20 clean-up and derivatization. Only solid-phase extraction procedure was used for LC-MS/MS. The samples were analysed in positive electro-spray ionization mode, monitoring the transitions for cortisol and deuterated-cortisol at m/z 363.3 > 121.2 and m/z 365.3 > 122.2, respectively. Immunoassays were performed according to the manufacturer's instructions. Results When compared with GC-MS results both immunoassays (Coat-A-Count; approximately 1.9-fold, Centaur; approximately 1.6-fold) overestimated UFC concentrations. Cortisol ring-A dihydro- and tetrahydrometabolites contribute significantly to this overestimation. There was no interference by these metabolites in either GC-MS or LC-MS/MS methods. The sensitivity of the LC-MS/MS procedure was 2 nmol/L and the intra- and inter-assay variations were <5% in each quality-control sample. The comparison of the UFC results achieved by assaying the study samples with GC-MS and LC-MS/MS indicated that the agreement between the two methods was excellent (LC-MS/MS = 1.0036GC-MS – 0.0841; r 2 = 0.9937). Conclusions The interference of cortisol ring-A metabolites in immunoassays contribute to overestimation of UFC concentrations. The LC-MS/MS procedure had the sensitivity, specificity, linearity, precision and accuracy for the determination of UFC concentrations. The method is suitable for routine use provided that method-dependant reference values are established.
The association of advanced glycation end-products with glutathione status
Authors: Şahin Emel , Göçmen Ayşe Yeşim , Koçak Hüseyin , Tuncer Murat , Gümüşlü Saadet 
Published: June 2008

Background The aim of this study was to investigate oxidative stress with regard to the concentrations of advanced oxidation protein products (AOPP), advanced glycation end-products (AGEs), pentosidine, glycated albumin, reduced glutathione (GSH) and oxidized glutathione (GSSG), glutathione redox ratios and thiobarbituric acid-reactive substances (TBARS) in non-diabetic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Methods The study group consisted of 52 non-diabetic CAPD patients and 34 healthy controls. AOPP, AGEs, pentosidine and glycated albumin were measured in plasma, whereas GSH, GSSG and TBARS concentrations were measured in erythrocytes of both patients and controls. Results All parameters were found to be significantly increased, except the glutathione redox ratio, which was found to be decreased in patients undergoing CAPD. Multiple regression analysis showed that AGEs were the only independent predictor of glutathione redox ratio, whereas AGEs, glycated albumin and TBARS were each found to be independent predictors of albumin concentration. Conclusion Our results support the hypothesis that oxidative stress and AOPPs/AGEs constitute important risk factors in CAPD patients. The negative relationship between albumin and both AGEs and TBARS suggests that the decrease in albumin may contribute to the increased advanced glycation and lipid peroxidation. The negative relationship between glutathione redox ratio and AGEs suggests that late products of glycation play an important role in the development of oxidative stress observed in patients undergoing peritoneal dialysis treatment.
Detection of citrullinated proteins in synovial fluids derived from patients with rheumatoid arthritis by proteomics-based analysis
Authors: Tabushi Yoko , Nakanishi Toyofumi , Takeuchi Tohru , Nakajima Mikio , Ueda Kazuhito , Kotani Takuya , Makino Shigeki , Shimizu Akira , Hanafusa Toshiaki , Takubo Takayuki 
Published: June 2008

Background Rheumatoid arthritis (RA) is the most common inflammatory joint disease. The aetiology of RA remains unknown, but autoimmune responses are considered to play an important role in the disease pathophysiology. Currently available data suggests that the process of diagnosing RA may benefit from testing for anticyclic citrullinated peptides. Identification of the presence of citrullinated proteins in rheumatoid synovial fluids is important for the elucidation of the aetiology of RA as well as in the differential diagnosis of rheumatic-related diseases. Methods A proteomics-based approach using electrophoresis/mass spectrometry was applied to identify the citrullinated proteins in synovial fluids from patients with RA. Synovial fluids from patients with RA were subjected to sodium dodecyl sulfate–polyacrylamide gel electrophoresis and Western blot analysis to detect the citrullinated proteins. Identification bands were then subjected to mass spectrometry. Results Three proteins – citrullinated fibrinogen, citrullinated fibronectin and citrullinated vimentin – in synovial fluids from RA patients were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Conclusions Proteomics-based analysis can be used to detect citrullinated proteins in synovial fluids from RA patients.
Central pontine myelinolysis complicating treatment of the hyperglycaemic hyperosmolar state
Authors: O'Malley Grainne , Moran Carla , Draman Mohd Shazlie , King Tom , Smith Diarmuid , Thompson Chris J , Agha Amar 
Published: June 2008

Central pontine myelinolysis (CPM) is well recognized to occur in a variety of clinical settings, but particularly following rapid correction of severe hyponatraemia. The development of CPM as a result of rapid shifts in plasma osmolality during the treatment of the hyperglycaemic hyperosmolar state (HHS) has hitherto been described in only one case. We report a second case in which this complication occurred in association with treatment of the HHS. The patient was a 49-year-old woman who presented to another hospital with drowsiness and a plasma glucose of 106 mmol/L. Her admission plasma sodium was 135 mmol/L. She received treatment with intravenous insulin and 0.9% normal saline, and there was a rapid drop in plasma glucose by 60 mmol/L within 6 h, which was associated with a rebound rise of plasma sodium to 159 mmol/L. Her plasma glucose and sodium were later stabilized. When the patient was transferred to our hospital a few days later, she was noted to have flaccid quadraparesis and pseudobulbar palsy. A magnetic resonance imaging scan revealed a pontine lesion consistent with CPM. She made a gradual recovery over several months with intensive rehabilitation and eventually returned to near normal functional capacity. This is the second case report in the literature of CPM complicating the management of HHS and highlights the importance of the judicious and measured correction of hyperglycaemia and the appropriate management of fluid replacement and electrolyte balance when treating this condition.
Can plasma ammonia be measured in patients with acute liver disease?
Authors: Herrera Daniel Juan , Moore Steven , Heap Sarah , Preece Mary Anne , Griffiths Paul 
Published: June 2008

Background Plasma ammonia (PA) measurement is of key importance in the diagnosis and monitoring of some inherited metabolic disorders and to monitor subsequent treatment of hyperammonaemia. Methods Over a six-month period, patients' ammonia concentrations were measured in parallel, using an enzymatic–UV kit (Infinity Ammonia Liquid Stable Reagent, Thermo Electron Corporation, Australia) on an Olympus AU640 analyser (Olympus UK Ltd, Hertfordshire) and on our current dry chemistry system (Vitros 250, Ortho Clinical Diagnostic). Alanine amino transferase (ALT) was added to a human plasma sample to investigate its effect on the assessment of ammonia concentration. Results Both methods correlated well (InfinityTM kit = 1.12 × Vitros 250 + 39, R2 = 0.95, n = 105). However, clinically important discrepancies ranging from 100 to 380 μmol/L were found in patients with acute liver failure. Ammonia concentration measured with the enzymatic Infinity™ kit increased by 137 μmol/L when ALT was added up to 17,000 IU/L. Conclusions ALT produces a positive interference in the enzymatic Infinity™ kit which may affect interpretation and influence further clinical action. However, this positive interference due to ALT does not fully explain the discrepant results observed between the two methods in patients with acute liver failure.
Plasma insulin concentrations during a hyperinsulinaemic clamp: what do we measure?
Authors: Ackermans M T , Klieverik L P , Endert E , Sauerwein H P , Kalsbeek A , Fliers E 
Published: June 2008

Background The aim of this study is to compare the performance of three commonly used insulin assays with respect to the detection of exogenous human and porcine insulin added to human or rat plasma. Methods The DPC Immulite human insulin assay, the Mercodia rat insulin enzyme-linked immunosorbent assay and the Linco rat insulin radioimmunoassay were tested. Results The mean cross-reactivity of exogenous insulin ranged from 25% to 92%. The mean cross-reactivity of Actrapid in human plasma on the DPC Immulite was 56% and was independent of the endogenous insulin concentration. Conclusions The measurement of exogenous insulin varies according to the source of exogenous insulin, matrix and insulin assay.
Plasma lipoprotein β-amyloid in subjects with Alzheimer's disease or mild cognitive impairment
Authors: Mamo J C L , Jian L , James A P , Flicker L , Esselmann H , Wiltfang J 
Published: June 2008

Background Plasma amyloid β-peptide (Aβ) can compromise the blood-brain barrier, contributing to cerebrovascular alterations and amyloid angiopathy in Alzheimer's disease (AD). The objectives of this study were to investigate the distribution of lipoprotein-bound plasma-Aβ isoforms. Methods This involved a case-control study of subjects with AD or amnestic mild cognitive impairment (MCI) versus controls. Lipoprotein Aβ distribution was determined in fasted plasma. For assessment of chylomicron homeostasis in the postabsorptive state, subjects were bled 4 h after a low-fat meal. The main outcome measures were plasma lipoprotein Aβ isoform distribution and lipid homeostasis. Results We found the majority of plasma Aβ to be associated with triglyceride-rich lipoproteins (TRLs) encompassing chylomicrons, VLDL and IDL. For all lipoprotein groups, Aβ1–40 was the predominant isoform, accounting for approximately 50% of the total. Thereafter, equivalent amounts of the isoforms 1–42, 2–40, 1–38, 1–37 and 1–39 were found. Aβ1–37, Aβ1–38 and Aβ2–40 isoforms were significantly enriched within the TRL fraction of AD/MCI subjects and similar trends were observed for isoforms Aβ1–39, Aβ1–40 and Aβ1–42. Lipoprotein-Aβ was inversely associated with plasma total- and LDL cholesterol. AD/MCI subjects were not dyslipidaemic, however, there was evidence of accumulation of chylomicrons in the postabsorptive state. Conclusions Our data show that Aβ was found to be associated with plasma lipoproteins, especially those enriched with triglyceride. We find that Aβ may be increased in normolipidaemic AD subjects, commensurate with possible disturbances in postprandial lipoprotein homeostasis.
Measurement of plasma lysophosphatidic acid concentration in healthy subjects: strong correlation with lysophospholipase D activity
Authors: Hosogaya Shigemi , Yatomi Yutaka , Nakamura Kazuhiro , Ohkawa Ryunosuke , Okubo Shigeo , Yokota Hiromitsu , Ohta Masato , Yamazaki Hirokazu , Koike Toru , Ozaki Yukio 
Published: June 2008

Background Lysophosphatidic acid (LPA) plays important roles in a variety of biological responses, especially in the area of vascular biology, and the determination of its plasma concentration is believed to be important. Several mechanisms are known to be involved in the metabolism of LPA. Methods To identify factors that may determine the plasma concentrations of this important bioactive lipid, we examined its concentrations using an enzymatic cycling assay and related parameters in 146 healthy subjects. Results The LPA concentration was significantly higher in women (mean ± SD, 0.103 ± 0.032 μmol/L; n = 47) than in men (0.077 ± 0.026 μmol/L; n = 99). A multiple regression analysis showed a strong positive correlation between the plasma LPA concentration and serum lysophospholipase D (lysoPLD) activity, while the LPA concentration was correlated with the plasma lysophosphatidylcholine (LPC) concentration only in men. Other lipid-related parameters were only slightly correlated or were not correlated with the LPA concentration. Conclusions Our findings suggested that conversion from LPC by lysoPLD might be the major route for LPA production in plasma.
Clinical impact of variability in HbA1c as assessed by simultaneously measuring fructosamine and use of error grid analysis
Authors: Macdonald David R , Hanson Alison M , Holland Martin R , Singh Baldev M 
Published: June 2008

Background Haemoglobin A1c (HbA1c) is the only measure of glycaemic control used for many patients with diabetes, but it has limitations and might sometimes be misleading. HbA1c concentrations are influenced by conditions that alter red-cell life and there is evidence that biochemical variation in intracellular glycation rates also influence HbA1c concentrations. This paper is the first to propose a method of using simultaneously measured HbA1c and fructosamine, and error grid analysis, in the clinical setting, to gain a better understanding of glycaemic control. Methods Cross-sectional analytical study using HbA1c and fructosamine measures on the same blood sample from 1744 patients having blood taken for hospital diabetes clinic appointments. No other selection or exclusion criteria were applied. Results The fructosamine results were converted to a HbA1c equivalent which was then compared with the HbA1c. In an Altman-Bland plot, the paired result differences ranged between −6.9% and +5.5% HbA1c with 1139 (65%), 438 (25%), 130 (8%) and 37 (2%) being ≤1%, 1–2%, 2–3% or >3% of HbA1c difference, respectively. In clinical error grid analysis, 864 (50%) results had tight concordance for clinical interpretation, 761 (43%) had one block disunity of probably little clinical significance, but 105 (6%) were two blocks and 14 (1%) were three blocks discordant. Conclusion HbA1c may not accurately reflect glucose control. Our method, utilizing co-assessment with serum fructosamine, evaluates the possible clinical impact of this. We suggest the analysis used in this paper should be used routinely in diabetes practice.
Serum osteoprotegerin concentrations are decreased in women with the polycystic ovary syndrome
Authors: Escobar-Morreale Héctor F , Botella-Carretero José I , Martínez-García Ma Ángeles , Luque-Ramírez Manuel , Álvarez-Blasco Francisco , Millán José L San 
Published: June 2008

ObjectiveOsteoprotegerin (OPG), an inhibitor of osteoclastic bone resorption, has a variety of functions including anti-inflammatory effects and a possible cardiovascular protective role. Both low-grade chronic inflammation and cardiovascular risk are increased in women with the polycystic ovary syndrome (PCOS). We aimed to study serum OPG concentrations in PCOS patients.DesignCase–control study including 40 PCOS patients matched with 40 non-hyperandrogenic women for age and body mass index.MethodsBasal serum sampling and standard oral glucose tolerance test, and measurement of serum OPG concentrations by commercial ELISA.ResultsSerum OPG concentrations were lower in women with PCOS compared with those of controls (304±120 vs 363±105 pg/ml respectively; F=7.641, P=0.007) independently of obesity. No differences were observed in serum receptor activator of nuclear factor-κB ligand (RANKL) levels and in the RANKL/OPG molar ratio. A multivariate linear regression model (R2=0.208, F=6.579, P=0.001) showed that PCOS (β=−0.281, P=0.008), obesity (β=−0.245, P=0.022) and age (β=0.296, P=0.006) were predictive of serum OPG concentrations.ConclusionsSerum OPG concentrations are reduced in PCOS patients independently of obesity. Considering the anti-inflammatory effects of OPG, its reduced serum concentrations might contribute to the proinflammatory state and cardiovascular risk of PCOS patients.
Interplay of DNA Repair Pathways Controls Methylation Damage Toxicity in Saccharomyces cerevisiae
Authors: Cejka Petr , Jiricny Josef 
Published: June 2008

Abstract
Methylating agents of SN1 type are widely used in cancer chemotherapy, but their mode of action is poorly understood. In particular, it is unclear how the primary cytotoxic lesion, O6-methylguanine (MeG), causes cell death. One hypothesis stipulates that binding of mismatch repair (MMR) proteins to MeG/T mispairs arising during DNA replication triggers cell-cycle arrest and cell death. An alternative hypothesis posits that MeG cytotoxicity is linked to futile processing of MeG-containing base pairs by the MMR system. In this study, we provide compelling genetic evidence in support of the latter hypothesis. Treatment of 4644 deletion mutants of Saccharomyces cerevisiae with the prototypic SN1-type methylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) identified MMR as the only pathway that sensitizes cells to MNNG. In contrast, homologous recombination (HR), postreplicative repair, DNA helicases, and chromatin maintenance factors protect yeast cells against the cytotoxicity of this chemical. Notably, DNA damage signaling proteins played a protective rather than sensitizing role in the MNNG response. Taken together, this evidence demonstrates that MeG-containing lesions in yeast must be processed to be cytotoxic.
The Albian (Vraconnian)-Cenomanian boundary at the western Tethyan margins (Central Tunisia and southeastern France)
Authors: Robaszynski Francis , Amédro Francis , González-Donoso Jose Maria , Linares Dolores 
Published: June 2008

AbstractThrough the description and interpretation of the position of macro- and microfossils in several sections of the Albian-Cenomanian boundary in SE France and Central Tunisia, a comparison is made between the north and south margins of the Tethyan Ocean by using the occurrences of marker bioevents. For the planktonic foraminifera, the criterions applicable for the accurate determination of Thalmanninella globotruncanoides (Sigal) – the marker species for the base of the Cenomanian stage – are discussed. The species Th. globotruncanoides and the intermediate forms with its ancestor Th. caroni (Ion) are illustrated. For the ammonites, two subjects are new. Firstly, the species Stoliczkaia (Shumarinaia) africana Pervinquiere is illustrated since it is choosen as the indice of the uppermost zone of the Albian (Vraconnian). In northern Africa it replaces Arrhaphoceras (Praeschloenbachia) briacensis (Scholz), the indice for northern Tethys, but restricted to the North European Province. Secondly, specimens of the two genera Graysonites and Utaturiceras – first found in the basal Cenomanian of northern Africa – are described and illustrated.To allow a comparison between north and south Mediterranean sections, respectively Mont Risou and Marcoule for the north and Tunisia for the south, the stratigraphical position of several proxies from planktonic foraminifera, calcareous nannofossils and ammonites are discussed. A widening of the comparison is proposed by taking into account distant regions such as Madagascar and northern California.
The stratigraphic response to the Oligo-Miocene extension in the western Mediterranean from observations on the Sardinia graben system (Italy)
Authors: Cherchi Antonietta , Mancin Nicoletta , Montadert Lucien , Murru Marco , Putzu Maria Teresa , Schiavinotto Francesco , Verrubbi Vladimiro 
Published: June 2008

Abstract
The Sardinian Cainozoic rifted basin is a useful model for studying the stratigraphic response to the Oligo-Miocene structural extension in the western Mediterranean because it allows precise observations on the relationship between sedimentation and normal faulting based on outcrops and seismic reflection data. The purpose of this paper, essentially of stratigraphic nature is to propose a chronology as precise as possible of the tectonic events and of the sedimentary formations. Indeed the tectono-sedimentary framework is complex, characterized by an extreme facies variability, from continental to marginal transitional and to marine environments (shallow-water, hemipelagic). Rifting, active calc-alkaline volcanism and sea-level changes caused rapid physiographical evolution, which controlled progressive marine ingression. New chronobiostratigraphical data presented in this paper allow correlating the sequences, defining their environment and depth of deposition and specifying precisely the timing of pre-, syn-, and post-rift stages in the Oligo-Miocene graben system. In southwestern Sardinia during the middle-late Eocene, after the Pyrenean phase, a continental graben (Cixerri), W-E oriented, preceded the Oligo-Miocene extension, which reactivated inherited Eocene and Palaeozoic faults. The calc-alkaline volcanic activity ranging from 32 to 13 Ma, provides a good estimate for the time span of the west-dipping Apenninic subduction responsible for the continental extension and the oceanic accretion in the western Mediterranean. In Sardinia the Oligo-Miocene extensional tectonics started in a continental environment, preceding the earliest calc-alkaline volcanic products (32 Ma). The marine ingression is dated to the late Chattian-Aquitanian interval and corresponds to a rapid deepening of the Oligo-Miocene graben system of tectonic origin. The end of the rifting i.e. the end of normal faulting activity is pre-middle Burdigalian in age. When Sardinia was in the post-rift stage, extension continued until late Burdigalian – Langhian in the Algero-Provençal basin with oceanic accretion and rotation of the Corsica-Sardinia block (CSB).
Analysis of the ReSuMe Learning Process For Spiking Neural Networks
Authors: Ponulak Filip 
Published: June 2008

Analysis of the ReSuMe Learning Process For Spiking Neural NetworksIn this paper we perform an analysis of the learning process with the ReSuMe method and spiking neural networks (Ponulak, 2005; Ponulak, 2006b). We investigate how the particular parameters of the learning algorithm affect the process of learning. We consider the issue of speeding up the adaptation process, while maintaining the stability of the optimal solution. This is an important issue in many real-life tasks where the neural networks are applied and where the fast learning convergence is highly desirable.