bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of 5‐hydroxytryptamine, 5‐hydroxyindoleacetic acid and tryptophan in plasma and urine by HPLC with fluorimetric detection
Authors: Bearcroft C. P. , Farthing M. J. G. , Perrett D. 
Published: May 2005

AbstractUsing native fluorescence detection, 5‐hydroxytryptamine (5‐HT), 5‐hydroxyindoleacetic acid (5‐HIAA) and tryptophan were resoved from themselves and other naturally occurring compounds using reversed‐Phase HPLC within 5 min. Deproteinated platelet‐poor plasma (ppp) and crude diluted urine were injected directly into the chromatograph. Careful selection of the HPLC column is important and various octadecyl silica (ODS) and base deactivated silic (BDS) columns were evaluated. Pre‐treatment of an ODS column with tetrabutylammonium ions gave good selectivity. Between pH5 and 6 the compounds were well resolved from each other. The limit of quantitatiave detection of 5‐HT and 5‐HIAA was 3.5 nmol/L. The overal chromatogram obtained using native fluorescence is cleaner than that obtained with the more commonly employed electrochemical (EC) systems although the chromatography is effectively the same. For analysis of 5‐HT in plasma, collection in EDTA was more efficient than lithium heparin. Plasma 5‐HT in healthy volunteers was mean 61 (SD=±73) nmol/L, n=20; urine 5‐HIAA gave mean 28.95 (SD=±0.98)μmol/L, (n=12). Whole blood 5‐HT analysis is unreliable in comparison with platelet‐poor plasma.
N‐glycosylation site mapping of recombinant tissue plasminogen activator by micellar electrokinetic capillary chromatography
Authors: Taverna M. , Baillet A. , Schlüter M. , Baylocq‐Ferrier D. 
Published: May 2005

AbstractThis report describes the N‐glycosylation mapping of recombinant tissue plasminogen activator (rt‐PA) using micellar electrokinetic capillary chromatography. The carbohydrate structures were tentatively assigned by comparison with the anion‐exchange fractionated oligosaccharides and by a comparison with previously reported data. The separation was shown to rely mainly on the degree of sialylation of the oligosaccharides, allowing a quantitative determination of the proportion of neutral and mono‐ to tetrasialylated structures. Significant differences in the oligosaccharide distribution of the two variants of rt‐PA, which differ by the presence (type I) or the absence (type II) of oligosaccharides at the Asn‐184 site, were observed. The distribution of the oligosaccharides at each of the rt‐PA glycosylation sites was then determined. Glycopeptides were prepared by tryptic digestion of rt‐PA and isolated using two consecutive chromatographic procedures. The glycopeptides were finally treated with N‐glycanase, and the resulting oligosaccharides were analysed by capillary electrophoresis. Oligosaccharide mapping revealed that the Asn‐448 and Asn‐184 sites carry the same population of complex‐type oligosaccharides but that the relative amounts of each oligosaccharide vary markedly. High‐pH anion‐exchange chromatography performed on the desialylated oligosaccharides at each glycosylation site showed that the degree of microheterogeneity was related not only to the degree of sialylation but also to structural differences in the oligosaccharide sequences. From the results as a whole, we concluded that the Asn‐448 site contains a greater proportion of heavily sialylated structures and has a higher degree of microheterogeneity. The Asn‐117 site was demonstrated to contain a significant number of monosialylated structures (18.4%) in addition to the high‐mannose‐type oligosaccharides.
Occurrence of D‐aspartic acid in rat brain pineal gland
Authors: Imai Kazuhiro , Fukushima Takeshi , Hagiwara Kenichi , Santa Tomofumi 
Published: May 2005

AbstractWe found a high concentration (1030 pmol per pineal gland) of D‐aspartic acid (D‐Asp) in the pineal gland of 6‐week‐old Sprague‐Dawley (SD) rats. The content of D‐Asp decreased with age, being 210 and 33 pmol per pineal gland in 28‐ and 45‐week‐old rats respectively. The proportion of D‐Asp [(D‐Asp/total Asp) × 100] also decreased with age, declining from 66% to 10% between 6 and 45 weeks after birth. The proportion of D‐Asp did not differ between the sexes. The concentration of D‐Asp was higher at night (at 2.00 a.m. 2830±485 pmol per pineal gland) than during the day (at 10.00 a.m. 1030±200 and at 3:00 p.m. 682±194 pmol per pineal gland), suggesting that biosynthesis of D‐Asp in the pineal gland occurs at night. D‐Asp was found to be distributed in the cytosol of pinealocytes, but its biological role remains unclear.
Determination of medetomidine, atipamezole and midazolam in pig plasma by liquid chromatography‐mass spectrometry
Authors: Kanazawa Hideko , Nishimura Ryohei , Sasaki Nobuo , Takeuchi Akira , Takai Nobuharu , Nagata Yoshiko , Matsushima Yoshikazu 
Published: May 2005

AbstractMedetomidine, atipamezole and midazolam in pig plasma were determined by liquid chromatography‐mass spectrometry (LCMS) with an atmospheric pressure chemical ionization interface system by the use of detomidine as an internal standard. The method was applied to studies of pharmacokinetic behaviour of these drugs.
Chromatographic modelling of interactions between melanin and phenothiazine and dibenzazepine drugs
Authors: Radwa Aleksandra , Fra̧ckowiak Teresa , Ibrahim Houda , Aubry Anne‐Françoise , Kaliszan Roman 
Published: May 2005

AbstractDifferences in drug‐melanin interactions were determined for 13 phenothiazine neuroleptics and 2 dibenzazepine thymoleptics by means of high‐performace liquid chromatography. The chromatographic column was packed with a stationary phase obtained by chemical immobilization of synthetic L‐dopa melanin on silica particles. For six phenothiazines the melanin‐binding parameters were also determined by an ultrafiltration method. Correlation between measures of drug‐melanin interaction determined chromatographically and by the standard slow‐equilibrium method was significant, however moderate. The chromatographic method of assessing interactions between drugs‐melanin interaction determined chromatographically and by the standard slow‐equilibrium method was significant, however moderate. The chromatographic method of assessing interactions between drugs and melanin permitted reliable and quantitatively comparable data for representative series of solutes to be readily obtained. Such data were subjected to the analysis of quantitative structure‐retention relationships (QSRR). It was found that retention of the agents on the immobilized melanin column could be described by two‐parameter regression equations comprising the energy of the lowest unoccupied molecular orbital and either the water‐accessible surface area of a drug molecule or its hydrophobicity parameter, determined chromatographically on an immobilized artificial membrane column. The QSRR equation derived allows for the estimation of melanin binding based on the structure of a compound candidate, and thus rationalizes predictions of potential toxicity of drugs or drug candidates.
Resonance raman study on axial ligands of heme irons in cytochrome bd‐type ubiquinol oxidase from Escherichia coli
Authors: Hirota Shun , Mogi Tatsushi , Anraku Yasuhiro , Gennis Robert B. , Kitagawa Teizo 
Published: May 2005

AbstractResonance Raman (RR) spectra of cytochrome bd‐type ubiquinol oxidase enriched with Fe‐isotopes were investigated with excitation at 406.7, 424.0, 427.0, 441.6, and 647.1 nm. The bands of reduced form at 252 and 400 cm−1 were tentatively assigned to vFeHis of high‐spin b595 and vFeMet of low‐spin b558, respectively. The v and δFeOO bands of heme d‐O2 were observed at 566 and ∼445 cm−1, respectively. The vFeCO frequency of heme d‐CO was unusually low (477 cm−1) but the v4 frequency was not of P‐450 type. Therefore, the axial ligand of heme d would not be an ordinary histidine or cysteine. © 1995 John Wiley & Sons, Inc.
Competition of congo red and thioflavin S binding to amyloid sites in alzheimer's diseased tissue
Authors: Elhaddaoui A. , Pigorsch E. , Delacourte A. , Turrell S. 
Published: May 2005

AbstractThough the strong affinity of Congo red and thioflavin S for amyloid deposits has been known for a long time, the binding mechanism of these biological dyes to amyloid sites is still not understood. In the present work, the competition of these two dyes for binding in Alzheimer amyloid is investigated. Analyses by optical microscopy and microspectrofluorimetry were performed on several series of stained diseased brain sections. Microspectrofluorimetric analyses showed that bound Congo red and bound thioflavin S have characteristic spectra in which the fluorescence maxima are distinct of those for the free dyes. Both, optical microscopic analyses and fluorescence measurements of stained brain sections indicated that Congo red and thioflavin S compete with each other at the same interacting site on diseased cerebral tissue. The staining efficiency of the replacing dye seems to be a maximum for a concentration of about 1%. © 1995 John Wiley & Sons, Inc.
Subcellular localization of acetaldehyde dehydrogenase in human liver
Authors: Jenkins William J. , Peters Timothy J. 
Published: May 2005

AbstractThe subcellular distribution of aldehyde dehydrogenase activity was determined in human liver biopsies by analytical sucrose density‐gradient centrifugation. There was bimodal distribution of activity corresponding to mitochondral and cytosolic localizations. At pH 9.6 cytosolic aldehyde dehydrogenase had a lower apparent K for NAD (0.03 mmol l−1), than the mitochrondrial enzyme (K NAD = 1.1 mmol l−1). Also, the pH optimum for cytosolic aldehyde dehydrogenase activity (pH 7.5) was lower than that for the mitochondrial enzyme activity (pH 9.0), and the cytosolic enzyme activity was more sensitive to inhibition by disulfiram in vitro. Disulfiram (40 μmol l−1) caused a 70% reduction in cytosolic aldehyde dehydrogenase activity, but only a 30% reduction in mitochondrial enzyme activity after 10 min incubation. The liver cytosol may therefore be the major site of acetaldehyde oxidation in vivo in man.
Lipid peroxidation in hepatomas of different degrees of deviation
Authors: Rossi Maria Armida , Cecchini Giovanni 
Published: May 2005

AbstractLipid peroxidation rate in four different hepatomas is quite different and seems to be related to their degree of deviation, low deviation tumours displaying higher peroxidative ability. Moreover, the supernatant of the highly anaplastic Yoshida hepatoma is able to decrease the peroxidation rate in normal liver microsomes. This antioxidant ability is not dependent upon an increased level of glutathione. The concentration of reduced glutathione (GSH) declines strongly during incubation in conditions favouring lipid peroxidation. Unlike normal liver homogenates, this decline of GSH in hepatomas is not due to the transformation of GSH into oxidized glutathione (GSSG) but mostly to the increased activity of the γ‐glutamyl‐transpeptidase pathway.
Dispersed sensory ganglion cells cleave an active entity from nerve growth factor coupled to Sepharose
Authors: Khan A. A. , Pearce F. L. , Vernon C. A. 
Published: May 2005

AbstractDispersed sensory ganglion cells from the embryonic chick, but not cells from other tissues, liberate biologically active material from nerve growth factor coupled to Sepharose beads. Experiments with such insolubilized material cannot then be taken as evidence for the existence of an external membrane receptor for the factor and may indicate that responsive cells have the ability to cleave an active fragment from the polypeptide.
Biochemistry of the polyamines
Authors: Allen John C. 
Published: May 2005

AbstractThe naturally‐occurring polyamines exist in the free form, as N‐acetyl derivatives and bound to protein. Their biosynthesis is subject to sensitive control, particularly of ornithine decarboxylase. This enzyme may be multifunctional and a key regulatory protein. Studies, principally with selective inhibitors, have elucidated the roles of polyamines in cell proliferation. Oxidized polyamines, in contrast, can be potent mitotic inhibitors. These effects are reviewed in terms of their chemistry and biochemistry. Their principal distinctions are that they can be made or degraded intracellularly, they can associate electrostatically with macromolecules by means of their spaced cationic groups, and these can be readily converted to covalent bonds.
Surface of articular cartilage: Immunohistological studies
Authors: Duance V. C. 
Published: May 2005

AbstractUsing several physical techniques the surface of articular cartilage has been reported to be structurally different from the deeper layers. In this paper using immunohistochemical methods, the surface has been shown to contain a characteristically different collagen, Type I in contrast to Type II which is the major collagen of cartilage. These results support previous proposals for a surface layer, or lamina splendens, the presence of which would be of considerable importance in understanding the degradation of cartilage in arthritides.
Quantitative cytochemical analyses of ovarian luteal and interstitial cell RNA in relation to plasma progestins during pseudopregnancy in the rat
Authors: Doebler Jeffrey A. , Wickersham Edward W. , Anthony Adam 
Published: May 2005

AbstractLuteal and interstial cell RNA contents and circulating progesterone (P) and 20α‐hydroxypregn‐4‐ene‐3‐one (20α‐OH P) levels were measured during pseudopregnancy in order to characterize relationships between ovarian 20α‐OH P secretion and luteal regression. Functional luteolysis, as manifested in depressed P levels, was not associated with concurrent elevations in 20α‐OH P. Rather, augmented 20α‐OH P levels were evidenced in periovulatory periods at the onset and termination of pseudopregnancy, subsequent to RNA accumulation in both luteal and interstitial compartments. It is postulated that 20α‐OH P, the putative inactive metabolite of P, is produced by both ovarian compartments in a cyclic manner and in response to gonadotrophin released in the preovulatory period.
Effects of diterpene forskolin on the release reaction and protein phosphorylation of human platelets
Authors: González A. , Aranda E. , Mezzano D. , Garrido J. 
Published: May 2005

AbstractThe effects of diterpene forskolin on the human platelet release reaction and on platelet protein phosphorylation were studied. This drug is shown to have the same effects as other agents which increase cAMP levels, namely, it inhibits the secretory response to diverse agonists and causes changes in the phosphorylation of several specific proteins. An increase of the 32P content is seen in the MW 47 000, 24 000 and 21 000 polypeptides while a decrease is observed in the MW 41 000 and 27 000 and 20 000 species. Forskolin also inhibits the changes in protein phosphorylation pattern induced by the powerful platelet secretagogue, thrombin. Our results relate the effects of antagonists of platelet secretion such as prostaglandins more closely to changes in cAMP levels and in protein phosphorylation than to other possible effects of the receptor–ligand interaction, which is by‐passed by the use of forskolin. Our results also provide additional evidence involving these changes in the mechanisms which regulate the secretory process in platelets.
Altered distribution profiles of endoplasmic reticulum subfractions after incubation of Krebs II ascites cells with different concentrations of cytochalasin B
Authors: Fjose Anders , Pryme Ian F. 
Published: May 2005

AbstractInformation on the interaction between endoplasmic reticulum (ER) membranes and components of the skeletal network of the cell was gained by treating cells with the antimicrofilament agent cytochalasin B prior to cell disruption by nitrogen cavitation. Treatment of Krebs II ascites cells with cytochalasin B (5–10 μg ml−1) resulted in an increased yield of three ER membrane subfractions — heavy rough (HR), light rough (LR) and smooth (S) membranes, as judged by 3H‐choline incorporation in gradient fractions following discontinuous sucrose gradient centrifugation. The major increase was observed in the HR fraction. These results indicate that the actual yield of the respective ER membrane subfractions after cell disruption is dependent on the degree of direct and/or indirect interaction between individual ER membranes and actin containing filaments of the cytoskeleton in the intact cell.
Studies on rat liver mitochondria:4. Enzyme activities in mitochondria preserved at 0—4°C
Authors: da Silva Patricia Teixeira Padilha , Higuti Ilma Hiroko , Stencel Mario , Campello Annibal de Paiva , do Nascimento Aguinaldo José 
Published: May 2005

AbstractRat liver mitochondria, stored with the energy‐linked functions preserved or in aging conditions, were used to assay the activity of various enzymes during five days. The preservation of energy‐linked functions was monitored by the respiratory control coefficient. ATPase, cytochrome oxidase and NADH dehydrogenase showed increased activity when the energy‐linked functions were preserved. In aging conditions, cytochrome oxidase, NADH dehydrogenase and ATPase showed decreased activity. The ATPase activity increased only when mitochondria were stored in the presence of inhibitors of the electron transport chain. The activity of NADH oxidase did not change, and succinate oxidase and succinate dehydrogenase showed a small decrease in their activity. The enzymes of the matrix, α‐ketoglutarate dehydrogenase, malate dehydrogenase and aspartate aminotransferase showed little decrease in activity under either of the conditions of storage. The total protein content decreased slightly under both conditions of storage. These results show that the activity of the enzymes analysed was maintained at reasonable levels, when the energy‐linked functions of isolated mitochondria were preserved.
Hydrolysis of thyroglobulin inside isolated rat thyroid and liver lysosomes
Authors: Fouchier Francis , Dang Josseline , Bastiani Paul , Peyron Claude , Mego John L. 
Published: May 2005

AbstractIn vitro, poorly iodinated thyroglobulin (Tg) is hydrolysed at the same rate whether it is enclosed in thyroid or in liver lysosomes, while fully iodinated Tg is degraded faster inside liver lysosomes. After in vivo TSH administration, thyroid lysosomes hydrolyse fully iodinated Tg as fast as do liver lysosomes.
Distribution of non‐histone proteins between micrococcal nuclease sensitive and nuclease resistant chromatin from chicken cells with active and inactive genomes
Authors: Kiliańska Z. , Kłyszejko‐Stefanowicz L. 
Published: May 2005

AbstractChicken liver and erythrocyte nuclei were separated by mild treatment with micrococcal nuclease into nuclease sensitive (NS) and nuclease resistant (NR) fractions, differing in chemical composition and transcriptional activity in vitro. Nuclei, NS and NR fractions of both tissues were fractionated by hydroxyapatite chromatography into three groups of non‐histone chromatin proteins (NHCP) and characterized by SDS‐polyacrylamide gel electrophoresis. Some differences in the molecular distribution of non‐histone proteins of chicken liver and erythrocytes between nuclease sensitive and resistant parts of chromatin have been described.
Behaviour of cyclic nucleotides and Ca2+ levels in liver tissue of rats poisoned by white phosphorus and trichlorobromomethane
Authors: Paradisi L. , Panagini C. , Negro F. , Parola M. , Torrielli M. V. 
Published: May 2005

AbstractThe content of hepatic cyclic AMP was increased soon after intoxication by white phosphorus. Its level reached a maximum 4 h after poisoning, but in subsequent phases tended to return to normal. In contrast, the cyclic GMP concentration was altered only 24 and 36 h after treatment with the same hepatotoxin. Similar modifications of cAMP and cGMP content were also detected after poisoning by trichlorobromomethane (CBrCl3). As a consequence, an altered cGMP/cAMP ratio was found in both experimental conditions. Further, the modification of cAMP content after white phosphorus was detected prior to liver damage (steatosis and necrosis), while the highest concentration of the cyclic nucleotide in CBrCl3‐poisoned rats was found when fatty liver was already evident. In addition, in phosphorus‐poisoned rats, the hepatic content of Ca2+ was found to be unmodified during all phases of the intoxication, while after CBrCl3 a phasic increase of the Ca2+ level was observed at 4, 24 and 36 h.
Cyclic nucleotides and haemoglobin concentration in rabbit bone marrow cell suspensions stimulated by purified erythropoietin
Authors: Fanò G. , Menchetti G. , Secca T. , Marsili V. , Torre G. Della 
Published: May 2005

AbstractThis study was conducted to determine the possible correlations between cyclic nucleotides cyclic adenosine monophosphate (cAMP) and cyclic guanine monophosphate (cGMP), and haemoglobin (Hb) concentration in nucleated cell suspensions of rabbit bone marrow incubated with erythropoietin (Ep). The levels of cAMP and cGMP were measured following the addition of different Ep concentrations to the suspensions. The Hb concentration was also measured in suspensions treated with Ep, dibutyryl cAMP (db‐cAMP) or dibutyryl cGMP (db‐cGMP), respectively. The following results were obtained: (1) upon the addition of 1 IU ml−1 Ep, an increase of cAMP levels was related to an increase in Hb concentration; while a decrease of Hb concentration was related to an increase of cGMP levels obtained when 0.1 IU ml−1 Ep was present in the incubation mixture. (2) A mimetic effect on Hb concentration was obtained upon the addition of db‐cAMP or db‐cGMP to the suspensions. (3) A quantitative correlation was found between the cAMP/cGMP ratio and Hb levels in cellular suspensions. This rapport was reviewed with respect to the controls as a decrease in Hb concentration when the ratio is less than one and an increase in Hb concentration when the ratio is greater than one.
Metabolic and secretory effects of methylamine in pancreatic islets
Authors: Gomis R. , Deleers M. , Malaisse‐Lagae F. , Sener A. , Garcia‐Morales P. , Rovira A. , Valverde I. , Malaisse W. J. 
Published: May 2005

AbstractThe metabolic and secretory effects of methylamine in rat pancreatic islets were investigated. Methylamine accumulated in islet cells, was incorporated into endogenous islet proteins, and inhibited the incorporation of [2,5‐3H] histamine into either N,N‐dimethylcasein or endogenous islet proteins. Methylamine (2 mM) did not affect the oxidation of glucose or endogenous nutrients or the intracellular pH in islet cells. Glucose did not affect the activity of transglutaminase in islet homogenates, the uptake of 14C‐methylamine by intact islets or its incorporation into endogenous islet proteins. Methylamine inhibited insulin release evoked by glucose, other nutrient secretagogues, and non‐nutrient insulinotropic agents such as L‐arginine or gliclazide. The inhibitory effect of methylamine upon insulin release was diminished in the presence of cytochalasin B or at low extracellular pH. Methylamine retarded the conversion of proinsulin to insulin. Trimethylamine (0.7 mM) was more efficiently taken up by islet cells than methylamine (2.0 mM), and yet caused only a modest inhibition of insulin release. These findings suggest that methylamine interferes with a late step in the secretory sequence, possibly by inhibiting the access of secretory granules to their exocytotic site.