bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacokinetic tracer kinetics analysis of changes in erythropoietin receptor population in phlebotomy‐induced anemia and bone marrow ablation
Authors: Veng‐Pedersen P. , Chapel S. , Al‐Huniti N.H. , Schmidt R.L. , Sedars E.M. , Hohl R.J. , Widness J.A. 
Published: March 2004

AbstractObjectives—The objective was to studyin vivoerythropoietin (Epo) progenitor cell surface receptors (EpoR) in the bone marrow (BM) after phlebotomy and bone marrow ablation.Methods—Serial tracer interaction method experiments were conducted in adult sheep at baseline and after phlebotomy (PH) and ablation (AB). PH was done 10 days after phlebotomy (to 3–4 g/dl Hb), and the AB was done 8 days after a 3‐day oral treatment with bulsulfan (11 mg/kg/day).Results—Bone marrow ablation changed the elimination from non‐linear to linear, consistent with an abolition of the non‐linear elimination via BM EpoRs. The phlebotomy increased the linear clearance of the ablated elimination pathway (from 63.6±12 to 126±64 ml/h/kg), consistent with an up‐regulation of the erythroid progenitor BM‐based EpoR pool, but did not change the clearance of the non‐ablated elimination pathway(p>0.05). The EpoR pool size remaining after BM ablation was 7.4±2.7% of the pre‐ablation pool.Conclusions—Erythropoietin elimination via EpoR in the bone marrow was non‐linear and increased following phlebotomy‐induced anemia. This is consistent with an up‐regulation of the erythropoietic EpoR pool in BM. Assuming that the elimination of Epo after BM ablation was via non‐hematopoietic EpoR, then this post‐ablation EpoR population was not significantly up‐regulated by the phlebotomy. Copyright © 2004 John Wiley & Sons, Ltd.
Total synthesis of artificial zinc‐finger proteins: Problems and perspectives
Authors: Futaki Shiroh , Tatsuto Kiwada , Shiraishi Yasuhisa , Sugiura Yukio 
Published: March 2004

AbstractThe total synthesis of a peptide segment corresponding to the DNA‐binding segment of Sp1 (positions 532–623) using a native chemical ligation approach is described. The folding of the synthetic segment in the presence of Zn(II) gave a zinc‐coordinated protein. The dissociation constant (KD) for the DNA binding of the resulting protein, determined by a gel mobility shift assay, was 130 nM, almost nine times higher than that of the genetically prepared protein. However, methylation interference assay showed an identical sequence specificity of both proteins in DNA recognition. The chemical ligation method to connect the respective zinc‐finger units was also accomplished. Successive ligation between a cysteine‐containing peptide segment and a chloroacetylated peptide segment gave an artificial three‐finger protein, which corresponds to the above DNA‐binding segment of Sp1. However, this protein failed to bind DNA, even at 1.25 mM. Assessment of their folding structure based on the absorption spectra of their Co(II) complexes showed that the linker design to connect the respective finger units is critical for the proper folding of the proteins as well as the occurrence of the DNA‐binding function. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004
Growth behavior of microorganisms using UV‐Vis spectroscopy:Escherichia coli
Authors: Alupoaei Catalina E. , García‐Rubio Luis H. 
Published: March 2004

AbstractMultiwavelength transmission spectra of microorganisms and cell suspensions consist of combined absorption and scattering phenomena resulting from the interaction of light with microorganisms or cells typically suspended in a nonabsorbing media. The distribution of intensities as a function of wavelength depends on the size, shape, and optical properties of the sample. The optical properties are functions of the chemical composition and the state of aggregation, or association, of the chromophoric groups contained in the microorganisms. This article explores the growth behavior of Escherichia coli from the perspective of multiwavelength UV‐Vis spectroscopy. Experimentally, it is demonstrated that the spectral signatures of the microorganism evolve as a function of time. It is also demonstrated that the spectral changes observed during growth are consistent with data reported elsewhere. From the theoretical point of view, it is demonstrated that the spectral signatures can be adequately represented with an interpretation model based on light‐scattering theory. The parameters from the interpretation model reflect changes in size and chemical composition known to take place in the microorganisms during growth. © 2004 Wiley Periodicals, Inc.
Activity and enantioselectivity of wildtype and lid mutated Candida rugosa lipase isoform 1 in organic solvents
Authors: Secundo Francesco , Carrea Giacomo , Tarabiono Chiara , Brocca Stefania , Lotti Marina 
Published: March 2004

AbstractThe activity and enantioselectivity of lipase 1 from Candida rugosa and of a chimera enzyme obtained by replacing the lid of isoform 1 with the lid of isoform 3 were compared in organic solvents. The alcoholysis of chloro ethyl 2‐hydroxy hexanoate with methanol and of vinyl acetate with 6‐methyl‐5‐hepten‐2‐ol were used as model reactions in different reaction conditions. The chimera enzyme was less active and enantioselective than the wildtype in all the conditions tested. A rationale for such decreases could be that the chimera lipase has a lower proportion of enzyme molecules in the open form. This might lead to a hindered access to the enzyme active site, thus affecting the catalytic activity. © 2004 Wiley Periodicals, Inc.
Fundamental Escherichia coli biochemical pathways for biomass and energy production: creation of overall flux states
Authors: Carlson Ross , Srienc Friedrich 
Published: March 2004

AbstractWe have previously shown that the metabolism for most efficient cell growth can be realized by a combination of two types of elementary modes. One mode produces biomass while the second mode generates only energy. The identity of the four most efficient biomass and energy pathway pairs changes, depending on the degree of oxygen limitation. The identification of such pathway pairs for different growth conditions offers a pathway‐based explanation of maintenance energy generation. For a given growth rate, experimental aerobic glucose consumption rates can be used to estimate the contribution of each pathway type to the overall metabolic flux pattern. All metabolic fluxes are then completely determined by the stoichiometries of involved pathways defining all nutrient consumption and metabolite secretion rates. We present here equations that permit computation of network fluxes on the basis of unique pathways for the case of optimal, glucose‐limited Escherichia coli growth under varying levels of oxygen stress. Predicted glucose and oxygen uptake rates and some metabolite secretion rates are in remarkable agreement with experimental observations supporting the validity of the presented approach. The entire most efficient, steady‐state, metabolic rate structure is explicitly defined by the developed equations without need for additional computer simulations. The approach should be generally useful for analyzing and interpreting genomic data by predicting concise, pathway‐based metabolic rate structures. © 2004 Wiley Periodicals, Inc.
The capillary electrophoresis separation of benzodiazepine drug using dextran sulfate and SDS as running buffer
Authors: Suzuki Yoshio , Arakawa Hidetoshi , Maeda Masako 
Published: March 2004

AbstractCapillary electrophoresis has been applied the analyses of many clinical drugs due to its rapid, high‐resolution separation. In this study, electrokinetic chromatography involving the combination of SDS and dextran sulfate, which are synthetic polymers, was examined in order to obtain high resolution. Use of 2% dextran sulfate (10,000 molecular weight), 20 mm SDS running buffer containing boric acid solution (pH 9.2) and a silica capillary (inner diameter of 75 µm, effective length of 50 cm, 57 cm overall length) afforded separation of 10 kinds of benzodiazepines. The detection limit was 0.2 µg/mL; additionally, reproducibilities were deﬁned as the peak height and migration time. The average peak height was 5.92% (2.46–17.61), whereas the average migration time was 0.44% (0.18–0.76; n = 5). This separations system can be applied to the analysis and measurement of other pharmaceuticals as well. Copyright © 2004 John Wiley & Sons, Ltd.
A validated HPLC method with ultraviolet detection for the determination of buformin in plasma
Authors: Chou Chen‐Hsi , Cheng Ching‐Ling , Huang Chien‐Chen 
Published: March 2004

AbstractA sensitive and rapid high‐performance liquid chromatographic assay is developed and validated for the determination of buformin in plasma. After addition of metformin as the internal standard, the analytes were deproteinated with acetonitrile, washed with dichloromethane, and the resulting supernatant injected. Chromatography was performed at ambient temperature by pumping a mobile phase of 0.03 m diammonium hydrogen phosphate buffer (pH 7, 250 mL) in methanol (750 mL) at a ﬂow rate of 1 mL/min through a silica column. Buformin and metformin were detected at 236 nm, and eluted 9.8 and 15.4 min, respectively. No endogenous substances were found to interfere. Calibration curves were linear over the concentration range of 20–2000 ng/mL. The limit of quantitation was 20 ng/mL. The intra‐ and inter‐day relative standard deviation (RSD) was 8.3%, or less, and the accuracy was within 10.1% of the relative error (RE). The method is suitable in pharmacokinetic investigation of buformin. Copyright © 2004 John Wiley & Sons, Ltd.
Characterization of amyloidogenic immunoglobulin light chains directly from serum by on‐line immunoafﬁnity isolation
Authors: Bergen H. Robert , Abraham Roshini S. , Johnson Kenneth L. , Bradwell Arthur R. , Naylor Stephen 
Published: March 2004

AbstractPrimary systemic amyloidosis (AL) is characterized by the overproduction of immunoglobulin light chain proteins by a monoclonal, terminally differentiated B‐lymphocyte or plasma cell clone. The free immunoglobulin light chains are deposited in an abnormal conformation as amyloid in a variety of organs in the body. The mechanism of amyloid formation is not well understood, but appears to be associated with some form of cleavage of the immunoglobulin light chain with subsequent aggregate formation. In an attempt to characterize the structure of amyloid‐forming light chain proteins we developed an on‐line immunoafﬁnity puriﬁcation and subsequent characterization of free κ and free λ immunoglobulin light chains by electrospray ionization mass spectrometry. The methodology is totally automated and requires 20 µL of serum. Mass spectral analysis of Bence Jones proteins under non‐denaturing conditions was also utilized to examine the tertiary and quaternary structure of light chain proteins and clearly shows covalent dimer formation of lambda type light chain. This type of on‐line assay may prove helpful in elucidating distinguishing features capable of discriminating AL from benign monoclonal gammopathies of undetermined signiﬁcance as well as diagnosing AL. Copyright © 2004 John Wiley & Sons, Ltd.
Liquid chromatographic and mass spectrometric analysis of human serum acid alpha‐1‐glycoprotein
Authors: Kremmer T. , Szöllösi É. , Boldizsár M. , Vincze B. , Ludányi K. , Imre T. , Schlosser G. , Vékey K. 
Published: March 2004

AbstractHuman serum acid alpha‐1‐glycoprotein (AGP, orosomucoid) content of healthy individuals and cancer patients was measured, isolated and puriﬁed using a protocol of fast and biocompatible sample preparation, ion exchange and dye‐ligand afﬁnity chromatographic methods. In comparison to the healthy individuals signiﬁcantly higher serum AGP levels were found in a wide spectrum of cancer patients, indicating its diagnostic value in the malignant disease. Oligosaccharide content of AGP samples was separated following PNGase F enzyme digestion and analysed by RP‐HPLC and MALDI‐TOF mass spectrometry. RP‐HPLC and MALDI‐TOF mass spectrometric analysis of sugar constituents of AGP specimen originated from selected cancer patients with high serum AGP levels indicated the appearance of anomal distribution of bi‐, tri‐ and tetra‐antennary oligosaccharide structures compared to the healthy controls. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative analysis of phytoestrogens in kudzu‐root, soy and spiked serum samples by high‐pressure liquid chromatography
Authors: Benlhabib Elhabib , Baker John I. , Keyler Daniel E. , Singh Ashok K. 
Published: March 2004

AbstractA sensitive and reliable HPLC method that allows simultaneous quantiﬁcation of phytoestrogens extracted from kudzu‐root and soy preparations, and serum samples has been developed. Kudzu‐root and soy preparations were mixed with 5 µg ﬂavone and 15 µg rutin (internal standards) and the phytoestrogens were extracted by using solid‐phase (C18) extraction cartridges. Blank or spiked serum samples were extracted by using either C18 cartridges or trichloroacetic acid–methanol extraction. The extracts were analyzed by the HPLC equipped with a reverse‐phase (250 × 4 mm, C18) column and UV, diode‐array or MS detector. A linear gradient of acetic acid and acetonitrile provided excellent separation of glycoside and aglycone‐phytoestrogens from kudzu root and soy preparations. The C18 cartridge extraction of serum yielded excellent recovery of both glycoside‐ and aglycone‐phytoestrogens, while the trichloroacetic acid–methanol extraction yielded excellent recovery of glycoside but poor recovery of aglycone compounds. UV and MS detectors were suitable for phytoestrogen analysis in plant and serum samples, while the diode‐array detector was suitable for generating the UV absorbance curve for phytoestrogens. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation on liquid chromatographic separation of basic compounds using silica column with aqueous/organic mobile phase containing triethylamine and acetic acid
Authors: Wu An‐Bang , Huang Ming‐Chun , Ho Hsiu‐O , Yeh Geng‐Cheng , Sheu Ming‐Thau 
Published: March 2004

AbstractA high‐performance liquid chromatography (HPLC) method using silica column eluted with aqueous solvent mobile phase containing triethylamine (TEA) and acetic acid (ACH) at trace percentages was characterized for the analysis of basic compounds. The key mechanism of this system is ion‐exchange accompanying interaction of silanol groups. The increase in the ACH concentration in the mobile phase minimizes the ionization of the silanol group, leading to reduced retention time. However, the greater extent of ionization of silanol caused by the increase of TEA concentration helps to retain basic compounds in the column. Further, the protonated TEA that is positively charged also competes for the ionized silanol group with basic compounds, resulting in the modiﬁcation of retention time. On the other hand, the retention becomes longer with increasing proportion of either organic or aqueous solvent in mobile phase, and partial replacement of methanol with acetonitrile. Copyright © 2004 John Wiley & Sons, Ltd.
Identiﬁcation of photoproducts from imazosulfuron by HPLC
Authors: Morrica Patrizia , Fidente Paola , Seccia Serenella 
Published: March 2004

AbstractPhotolysis of imazosulfuron was studied in aqueous solution under UV light. The reaction followed a pseudo‐ﬁrst‐order kinetic with signiﬁcant correlation coefﬁcient.The major photodegradation products of imazosulfuron after irradiation under UV light were separated and tentatively identiﬁed by HPLC‐MS analysis as (4,6‐dimethoxypyrimidine‐2‐yl)aminocarbonylsulfamic acid, 4,6‐dimethoxy‐2‐ureidopyrimidine and 2,2′‐dichloro‐[3,3′] bi [imidazo[1,2‐a] pyridinyl]. The results indicate that different reaction pathways are followed: (1) cleavage of the sulfonylurea bridge; (2) desulfonylation, which can proceed either by a carbon–sulfur cleavage or a nitrogen–sulfur cleavage. A mechanism for the formation of the photoproducts is proposed. Copyright © 2004 John Wiley & Sons, Ltd.
Simultaneous determination of caffeine, theophylline and theobromine in human plasma by on‐line solid‐phase extraction coupled to reversed‐phase chromatography
Authors: Emara Samy 
Published: March 2004

AbstractA reversed‐phase liquid chromatographic column switching system was described for the determination of caffeine (CF), theophylline (TH) and theobromine (TB) in human plasma with a direct injection procedure. A short protein‐coated µBondapak CN silica pre‐column (20 × 3 mm, i.d.) was used for enrichment of the drugs and clean up from weakly retained plasma components using phosphate buffer saline pH 7.4. After washing step, the retained drugs were ﬂushed into a reversed‐phase column (5 µm TSK gel ODS‐80 TM, 150 × 4.6 mm i.d.) with a mobile phase of methanol–0.01 m phosphate buffer, pH 3.5 (30:70, v/v) for the ﬁnal separation. The eluent was monitored with a UV detector at 275 nm. The resulting chromatograms showed no interference from endogenous plasma components. A linear relationship between the concentration of drug and peak height was conﬁrmed in the range of 0.5–20 µg/mL for all drugs. High extraction recoveries from plasma ranging from 96.12 to 100.32% were achieved. Validation of the method was examined performing intra‐ and inter‐day accuracy and precision and was found to be satisfactory. The coefﬁcients of variation of the three drugs were less than 3% for intra‐day and less than 4% for inter‐day run assays. Copyright © 2004 John Wiley & Sons, Ltd.
Animating song
Authors: King Scott A. , Parent Richard E. 
Published: March 2004

AbstractWe describe techniques used to create animations of song. Modifications to a text‐to‐audiovisual‐speech system have been made to take the extra information of timing and frequency of the lyrics from a MIDI file. Lip‐synchronized animations of song are then produced. We discuss differences between the production of speech and the production of song. Copyright © 2004 John Wiley & Sons, Ltd.
Peptide‐Biphenyl Hybrids as Calpain Inhibitors
Authors: Montero Ana , Mann Enrique , Chana Antonio , Herradón Bernardo 
Published: March 2004

AbstractCalpain is a cysteine protease that is activated by Ca2+. The over‐activation of calpain, which occurs on increasing Ca2+ concentration, causes a variety of diseases. This paper reports experimental results on the inhibition of calpain I (μ‐calpain) by peptidebiphenyl hybrids. We have found that some peptidebiphenyl hybrids, with aromatic amino acids in the peptide chains, inhibit calpain with IC50 values in the nanomolar range. Since the peptidebiphenyl hybrids reported in the present paper do not posses a reactive electrophilic functionality, we hypothesize that they interfere with the activation of calpain by Ca2+, and present experimental and computational results on the binding of peptidebiphenyl hybrids to Ca2+.
Limbetazulone: a New ‘Decahydro‐8‐oxanaphtho[2,1‐f]azulen‐7‐one’ Diterpenoid from Ballota limbeta, and Occurence of Two Conformational Isomers in the Crystal
Authors: Riaz Muhammad , Krohn Karsten , Malik Abdul , Flörke Ulrich 
Published: March 2004

AbstractA new diterpenoid, limbetazulone (=(3S,4S,4aR,12bS)‐1,2,3,4,4a,5,6,11,12,12b‐decahydro‐3‐hydroxy‐4‐ (hydroxymethyl)naphtho[1′,2′: 5,6]cyclohepta[1,2‐b]furan‐7(7H)‐one; 1), with the very rare ‘naphtho[2,1‐f]azulene‐7‐one’ skeleton, was isolated from the aerial parts of the Asian medicinal plant Ballota limbeta. Its structure was established by extensive spectroscopic investigations, especially 1D and 2D NMR. X‐Ray diffraction studies showed the presence of two conformational isomers (1a and 1b) in the crystal.
Guanine 6‐O‐Methylation Pattern within the Dioxin Responsive Element of the CYP1A1 Enhancer Shows Two Critical Guanines for AhR/ARNT Binding
Authors: Oesch‐Bartlomowicz Barbara , Janssen Kai , Wiss Oliver , Oesch Franz 
Published: March 2004

AbstractThe core‐recognition motif for TCDD‐liganded AhR/ARNT complex of the dioxin‐responsive element (DRE) contains four guanine residues, three on the antisense (5′‐TT/AGCGTG‐3′) and one on the sense (5′‐CACGCA/TA‐3′) strand. It has been reported that, in methylation‐protection and methylation‐interference assays, the TCDD‐liganded AhR/ARNT contacts all four guanine residues. On the other hand, it is known that some anticancer drugs, and various environmental and workplace chemicals, including strongly human carcinogenic nitrosoamines, lead to the highly miscoding 6‐O‐methylation of guanine. In the present study, we have investigated whether specific methylation of guanine at the 6‐O‐position interferes with the binding of TCDD‐liganded AhR/ARNT complex to its recognition motif in the CYP1A1 enhancer, and how individual 6‐O‐methylated guanines contribute to this interference. We found that only two 6‐O‐methylguanine residues are critical: the closest to the 5′‐end within the three‐nucleotide sequence (5′‐GTG‐3′), identical to a half‐site E‐box element, on the antisense strand, and the only guanine on the sense strand. In contrast, the 6‐O‐methylguanine closest to the 5′‐end (well) and the one closest to the 3′‐end (to a lesser extent), both on the antisense strand, were still able to bind the TCDD‐liganded AhR/ARNT complex. This shows that the 6‐O‐methylation of guanine in the core sequences of CYP1A1 enhancer interferes with the binding of the ligand‐activated AhR/ARNT complex in a differentially selective manner; it fully impedes binding of this complex to DRE (the prerequisite of most of the toxic effects of TCDD) only when one of the two particular guanines is methylated at the 6‐O‐position.
Two Novel Hexadepsipeptides with Several Modified Amino Acid Residues Isolated from the Fungus Isaria
Authors: Ravindra Gudihal , Ranganayaki Rappal. S. , Raghothama Srinivasa , Srinivasan Mandayam C. , Gilardi Richard D. , Karle Isabella L. , Balaram Padmanabhan 
Published: March 2004

AbstractTwo new cyclohexadepsipeptides have been isolated from the fungus Isaria. Fungal growth in solid media yielded hyphal strands from which peptide fractions were readily isolable by organic‐solvent extraction. Two novel cyclodepsipeptides, isaridin A and isaridin B, have been isolated by reverse‐phase HPLC, and characterized by ESI‐MS and 1H‐NMR. Single crystals of both peptides have been obtained, and their 3D structures were elucidated by X‐ray diffraction. The isaridins contain several unusual amino acid residues. The sequences are cyclo(β‐Gly‐HyLeu‐Pro‐Phe‐NMeVal‐NMePhe) and cyclo(β‐Gly‐HyLeu‐β‐MePro‐Phe‐NMeVal‐NMePhe), where NMeVal is N‐methylvaline, NMePhe N‐methylphenylalanine, and HyLeu hydroxyleucine (=2‐hydroxy‐4‐methylpentanoic acid). The two peptides differ from one another at residue 3, isaridin A having an (S)‐proline at this position, while β‐methyl‐(S)‐proline (=(2S,3S)‐2,3,4,5‐tetrahydro‐3‐methyl‐1H‐pyrrole‐2‐carboxylic acid) is found in isaridin B. The solid‐state conformations of both cyclic depsipeptides are characterized by the presence of two cis peptide bonds at HyLeu(2)‐Pro(3)/HyLeu(2)‐β‐MePro(3) and NMeVal(5)‐NMePhe(6), respectively. In isaridin A, a strong intramolecular H‐bond is observed between Phe(4)CO⋅⋅⋅HNβ‐Gly(1), and a similar, but weaker, interaction is observed between β‐Gly(1)CO⋅⋅⋅HNPhe(4). In contrast, in isaridin B, only a single intramolecular H‐bond is observed between β‐Gly(1)CO⋅⋅⋅HNPhe(4).