bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimicrotubular effect of calvatic acid and of some related compounds
Authors: Gadoni Elena , Gabriel Ludovica , Olivero Antonella , Bocca Claudia , Miglietta Antonella 
Published: May 2005

AbstractA structure–activity relationship has been established between calvatic acid and some related synthetic compounds, and their ability to inhibit GTP‐induced microtubular protein polymerization in vitro. These compounds were effective in a dose‐ and a time‐dependent manner. The most active drug was the p‐chloro substituted compound, which showed its inhibitory activity without any preincubation period, which the others needed. Since if cysteine was present, polymerization was no longer affected, an involvement of titratable –SH groups of tubulin could be suggested. In contrast, taxol‐induced polymerization was only slightly inhibited by these compounds, and colchicine‐binding activity was not generally impaired.
The effect of insulin on macrophage metabolism and function
Authors: Rosa Luís F. B. P. Costa , Safi Danilo A. , Cury Yara , Curi Rui 
Published: May 2005

AbstractThis study examined the effect of insulin on rat macrophage metabolism and function. The following parameters were studied: cell migration in response to thioglycollate and BCG stimuli, macrophage phagocytic capacity, H2O2 production, glucose and glutamine metabolism as indicated by the measurement of enzyme activities, the utilization of metabolites and production and oxidation of substrates. The results indicate that insulin: (1) did not affect cell migration in response to thioglycollate and BCG; (2) enhanced the phagocytic capacity of macrophages and the production of H2O2 by macrophages; (3) increased the metabolism of glucose and reduced that of glutaminase.
Inositolphosphoglycans and diacylglycerol are possible mediators in the glycogenic effect of GLP‐1(7‐36)amide in BC3H‐1 myocytes
Authors: Galera C. , Clemente F. , Alcántara A. , Trapote M. A. , Perea A. , López‐Delgado M. I. , Villanueva‐Peñacarrillo M. L. , Valverde I. 
Published: May 2005

AbstractA potent glycogenic effect of GLP‐1(7‐36)amide has been found in rat hepatocytes and skeletal muscle, and specific receptors for this peptide, which do not seem to be associated with the adenylate cyclase—cAMP system, have been detected in these tissue membranes. On the other hand, inositolphosphoglycan molecules (IPGs) have been implicated as second messengers of the action of insulin. In this work, we have found, in differentiated BC3H‐1 myocytes, specific binding of [125I]GLP‐1(7‐36)amide, and a stimulatory effect of the peptide on glycogen synthesis, confirming the findings in rat skeletal muscle. Also, GLP‐1(7‐36)amide modulates the cell content of radiolabelled glycosylphosphatidylinositols (GPIs) and increases the production of diacylglycerol (DAG), in the same manner as insulin acts, indicating hydrolysis of GPIs and an immediate and short‐lived generation of IPGs. Thus, IPGs and DAG could be mediators in the glycogenic action of GLP‐1(7‐36)amide in skeletal muscle.
Reversal of doxorubicin resistance by the amiloride analogue EIPA in multidrug resistant human colon carcinoma cells
Authors: Pannocchia Antonella , Revelli Silvia , Tamponi Giacomo , Giorgianni Angelica , Todde Roberta , Bosia Amalia , Ghigo Dario 
Published: May 2005

AbstractAlthough multidrug resistance (mdr) may arise through a variety of mechanisms, the most widely studied and accepted form is associated with an increased concentration of P‐glycoprotein (P‐gp), a 170kd protein found in the membrane fraction of a number of mammalian cells. Since mdr seems to be related to the ability of resistant cells to extrude drugs and the circumvention of mdr is supposed to be due to the restored ability to accumulate drugs, membrane has been regarded as the crucial site for such a regulation and an important role for membrane ion exchangers has been suggested. The aim of this work was to elucidate whether the Na+/H+ antiporter is involved in the mechanism of regulation and circumvention of mdr and if 5‐(N‐ethyl‐N‐isopropyl) amiloride (EIPA), a selective inhibitor of the Na+/H+ exchanger, can modulate the functional expression of the mdr phenotype. The effect of EIPA on doxorubicin (DX) resistant cells (LoVo/DX) obtained from a human colon adenocarcinoma cell line (LoVo) was studied. EIPA at concentrations ranging from 10 to 50 μM was able to increase the antibiotic cytotoxicity in the resistant Lovo/DX cells. The reversal of DX resistance paralleled an increase of the ability of the cells to accumulate the drug. Both drug loading and sensitivity to the inhibitory effect of DX on cell proliferation were restored by EIPA in a dose‐dependent way. These results suggest a new mechanism of mdr reversal and indicate that amiloride and its derivatives may be useful in reversing DX resistance and in enhancing the clinical effectiveness of chemotherapeutics.
Comparison of different In Vitro tests for evaluating immune reactivity
Authors: Pugliese A. , Comito G. , Cantamessa C. , Pollono A. M. , Savarino A. 
Published: May 2005

AbstractWe performed some in vitro tests for the detection of the immune state and compared the results. In particular we studied the production of various cytokines obtained by stimulating peripheral blood mononucleated cells (PBMC) with different inducers, using optimal and suboptimal doses. This was compared with the results of blastic transformation of lymphocytes, and with the evaluation of the capping effect of macrophages, and of the Multitest Mérieux. The correlation between the different investigations was generally good. This permits a simplification of the study of immune reactivity, selecting some of the tests proposed. The use of suboptimal doses of inducers improves the evaluation of very moderate deficits and supplies an in vitro model for the study of immunomodulant drugs.
Influence of culture conditions on monoamine oxidase A and B activity in rat astrocytes
Authors: Carlo Pia , del Rio Meris , Violani Elisabetta , Sciabà Luigi , Picotti Giovanni B. 
Published: May 2005

AbstractAstroglial cells dispersed from newborn rat hemispheres were established in medium supplemented with 20 per cent fetal calf serum (FBS) and then grown to a confluent monolayer in the presence of 10 per cent FBS or charcoal‐stripped FBS (CS). Type 1 astrocytes were subcultured and either maintained under the same conditions of the primary cultures or converted to serum‐free chemically defined medium (CDM). No differences were found in either MAO A or MAO B activity of astrocytes grown in the presence of FBS or CS after 15 and 21 days in vitro (day 1 and 6 of subculture). In contrast, on day 21 both MAO A and MAO B activities were markedly higher in astrocytes subcultured in CDM compared with cells maintained in serum‐supplemented medium. This difference appeared to be due to increased number of enzyme molecules, since kinetic analysis showed an increase in Vmax of both MAO isoenzymes in serum‐free medium, but no change in Km. Consistently, the recovery of MAO A and MAO B activity after irreversible enzyme inhibition by clorgyline and deprenyl was faster in CDM than in FBS‐supplemented medium, indicating enhanced enzyme synthesis under serum‐free condition. Estimates of half‐lives for the recovery of MAO A and MAO B activity indicated that, under both culture conditions, type A activity had a higher turnover rate than type B. The effect of CDM on astrocyte MAO does not appear to be due to selection of a subpopulation of cells, but rather linked to a morphological change (differentiation) with increased synthesis of both MAO isoenzymes.
Effects of methylglyoxal on platelet hydrogen peroxide accumulation, aggregation and release reaction
Authors: Leoncini Giuliana , Poggi Massimiliano 
Published: May 2005

AbstractMethylglyoxal generates a slight increase in the basal level of hydrogen peroxide in platelets. The oxidation effect of methylglyoxal significantly potentiated by thrombin, depends on both the ketoaldehyde and the agonist concentrations. A further significant increase in hydrogen peroxide accumulation was obtained in platelets pretreated with the alkylating agent N‐ethylmaleimide which depletes GSH and blocks glutathione peroxidase. Resting platelets completely transform the ketoaldehyde into D(−)lactate, whereas stimulated platelets transform about 10–15 per cent of the metabolized methylglyoxal into D(−)lactate. The metabolic modifications generated by methylglyoxal such as the GSH depletion and hydrogen peroxide accumulation induce modifications in platelet function. Methylglyoxal inhibits platelet aggregation induced by several agonists and ATP release induced by thrombin.
Hepatic and pancreatic effects of polyenoylphosphatidylcholine in rats with alloxan‐induced diabetes
Authors: Buko Vyacheslav , Lukivskaya Oxana , Nikitin Vasily , Tarasov Yury , Zavodnik Lev , Borodinsky Alexandr , Gorenshtein Bronislava , Janz Barbara , Gundermann Karl‐Josef , Schumacher Rainer 
Published: May 2005

AbstractPolyenoylphosphatidylcholine (PPC: 100 or 300 mg kg−1 b.w., by gastric intubation for 30 days) produced a clearcut protection of the liver of rats treated with alloxan (150 mg kg−1 b.w., i.p.). The liver of rats treated with alloxan was characterized by hydropic dystrophy and lymphocytic infiltrations. Treatment with alloxan increased serum γ‐GT and ALAT activities. The liver structure of rats treated with PPC did not differ from the liver of control animals. PPC normalized the biochemical abnormalities caused by the diabetes. The number of pancreatic islets and β/α; cell ratio decreased in the diabetic rats. A number of β‐cells in this group did not contain granules. PPC prevented the decrease in the number of islets and the β/α; cell ratio in the pancreas of the diabetic rats. The intensity of staining of β‐cell granules in the pancreas of PPC‐treated rats had a position intermediate between the control and diabetic groups. Alloxan increased the blood glucose content where treatment with PPC decreased this. The results suggest that PPC acts as a cytoprotector in the liver and pancreas of rats with experimental diabetes induced by alloxan.
Cytotoxicity of two new ribosome‐inactivating proteins, cinnamomin and camphorin, to carcinoma cells
Authors: Ling Jun , Liu Wang‐Yi 
Published: May 2005

AbstractCinnamomin (two‐chain) and camphorin (single‐chain), two novel ribosome‐inactivating proteins (RIPs) purified from the seeds of Cinnamomum camphora, produced inhibitory effects in cultured carcinoma cells. The IC50 of cinnamomin to the human hepatocarcinoma cell‐line 7721 and the melanoma cell‐line M21 were 18·8 nmol and 11·7 nmol respectively. The IC50 of camphorin to the human hepatocarcinoma cell‐line 7721 was 59 nmol, whereas the melanoma cell‐line M21 was not susceptible to camphorin. Furthermore, cinnamomin exhibited a remarkable inhibitory effect on the growth of solid melanoma in the skin of the nude mouse. An R‐fragment could be isolated from ribosomes of cinnamomin‐ or camphorin‐treated carcinoma cells after incubation with acidic aniline, indicating that the cytotoxicity of these two new RIPs to carcinoma cells might result from modification to the ribosomes.
Effect of 4‐hydroxynonenal on superoxide anion production from primed human neutrophils
Authors: Dianzani Chiara , Parrini Marinella , Ferrara Cinzia , Fantozzi Roberto 
Published: May 2005

AbstractHNE (4‐hydroxy‐2,3‐trans‐nonenal), an aldehydic product of lipid peroxidation, has been reported to modulate different functional parameters of human and rat neutrophils (PMNs), such as chemiluminescence, migration and some enzymatic activities, thus exerting effects that varied according to the concentration tested. Experiments were done to evaluate the effects of HNE on superoxide anion (O2−.) production from human PMNs, isolated from healthy volunteers. After having tested that HNE by itself was not able to activate the cells, comparisons were made between its effects on PMNs, stimulated by either a single stimulus, N‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP), or a combination of stimuli, such as FMLP and the neuropeptide substance P (SP; primed PMNs). In the concentration range tested (10−12–10−4 M), HNE inhibited FMLP‐evoked O2−. production with an IC50 of 11·6 ± 1·5 × 10−6 M; at concentrations ≤10−6 M, HNE enhanced O2−. production elicited by FMLP + SP, while higher concentrations were inhibitory. There was a bell‐shaped dose–response curve to the enhancing effects of HNE, depending on the incubation time being recorded after only short periods (≤5 min) of the exposure of the cells to HNE; this was not shown by structurally‐related aldehydes, such as 2‐nonenal and nonanal. These results suggest that low concentrations of HNE may participate in the evolution of the inflammatory process, by contributing to the activation of PMNs. The effects of high concentrations of the aldehyde may represent a mechanism which contributes to the regulation of the extent of the inflammatory response.
The expression of the human chorionic gonadotropin beta subunit gene depends on negative control
Authors: Chen Yen‐Hui , Chen Tzer‐Ming , Hsieh Chang‐Yao 
Published: May 2005

AbstractTranscription of the human chorionic gonadotropin (hCG) genes begins in the very early embryo stage and decreases or even disappears in nonplacental tissues. We have studied the regulation of hCG‐beta genes by cell fusion and by the reverse transcription‐polymerase chain reaction (RT‐PCR). The choriocarcinoma cell lines, JAR and JEG‐3, express high levels of the hCG‐beta subunit while HeLa cells express extremely low levels of it. Most HeLa × JAR and HeLa × JEG‐3 fusion clones expressed only a trace of the hCG‐beta subunit mRNA, while JAR × JEG‐3 fusion clones still expressed high levels of the hCG‐beta subunit. Most transcripts of the hCG‐beta subunit genes in JAR and JEG‐3 came from the hCG‐beta 5 subunit. Even the trace amount of hCG‐beta transcripts from fusion clones came mainly from the beta‐5 gene. The results suggest that the expression of the hCG‐beta subunit genes depends on negative control. Probably when embryonic cells differentiate to form nonplacental tissues, specific inhibitors may appear and inhibit the expression of the hCG‐beta subunit genes.
A PLS kernel algorithm for data sets with many variables and fewer objects. Part 1: Theory and algorithm
Authors: Rännar Stefan , Lindgren Fredrik , Geladi Paul , Wold Svante 
Published: May 2005

AbstractA fast PLS regression algorithm dealing with large data matrices with many variables (K) and fewer objects (N) is presented For such data matrices the classical algorithm is computer‐intensive and memory‐demanding. Recently, Lindgren et al. (J. Chemometrics, 7, 45–49 (1993)) developed a quick and efficient kernel algorithm for the case with many objects and few variables. The present paper is focused on the opposite case, i.e. many variables and fewer objects. A kernel algorithm is presented based on eigenvectors to the ‘kernel’ matrix XX TYYT, which is a square, non‐symmetric matrix of size N × N, where N is the number of objects. Using the kernel matrix and the association matrices XXT (N × N) and YYT (N × N), it is possible to calculate all score and loading vectors and hence conduct a complete PLS regression including diagnostics such as R2. This is done without returning to the original data matrices X and Y. The algorithm is presented in equation form, with proofs of some new properties and as MATLAB code.
Generalized rank annihilation method. I: Derivation of eigenvalue problems
Authors: Faber N. M. , Buydens L. M. C. , Kateman G. 
Published: May 2005

AbstractRank annihilation factor analysis (RAFA) is a method for multicomponent calibration using two data matrices simultaneously, one for the unknown and one for the calibration sample. In its most general form, the generalized rank annihilation method (GRAM), an eigenvalue problem has to be solved. In this first paper different formulations of GRAM are compared and a slightly different eigenvalue problem will be derived. The eigenvectors of this specific eigenvalue problem constitute the transformation matrix that rotates the abstract factors from principal component analysis (PCA) into their physical counterparts. This reformulation of GRAM facilitates a comparison with other PCA‐based methods for curve resolution and calibration. Furthermore, we will discuss two characteristics common to all formulations of GRAM, i.e. the distinct possibility of a complex and degenerate solution. It will be shown that a complex solution‐contrary to degeneracy‐should not arise for components present in both samples for model data.
Electrochemical detection as an alternative to UV in RP‐HPLC peptide mapping
Authors: Chen L. , Krull I. S. 
Published: May 2005

AbstractThis article describes the possibility of electrochemical (EC) detection as an alternative to ultraviolet (UV) detection doing peptide mapping. The high sensitivity and selectivity of the electrochemical detection can be applied to determine some digested peptides. This approach demonstrated that peptides containing electroactive amino acids can be determined by EC detection. Furthermore, upon irradiation, nonelectroactive amino acids and peptides can be made electroactive, thereby increasing the sensitivity and selectivity of peptide mapping. A variety of effects are discussed to help in understanding the possibility of this useful approach.
Complexation of trialkyllead with diethyldithiocarbamate
Authors: Mikac Nevenka , Branica Marko 
Published: May 2005

AbstractSodium salt of diethyldithiocarbamate (NaDDC) is one of the best‐known organic reagents which form extractable chelates with many metal ions. Although many data on the characteristics of metal‐DDC complexes have been published, no information about organometal complexes is available. In this work, the calculation of stability constants of trialkyllead‐DDC complexes is described and their values are measured by electrochemical techniques. Obtained values are (1.9 ± 0.7) × 106 for (C2H5)3PbDDC and (3.1 ± 1.5) × 105 for (CH3)3PbDDC. The application of these constants for the prediction of trialkylleads behavior during complexometric extraction from water to organic solvent is discussed.
Electrode modification with a poly(NiII‐tetramethyldibenzotetraaza[14]annulene) film. Electrochemical behavior and redox catalysis in alkaline solutions. I
Authors: Cataldi Tommaso R. I. , Centonze Diego , Ricciardi Giampaolo 
Published: May 2005

AbstractThe voltammetric behavior in alkaline solution of a nickel‐based chemically modified electrode (Ni‐CME) prepared by oxidative electropolymerization of a nickel–tetraazaannulene complex (NiIIL) was investigated. After electrochemical deposition of the (NiIIL)n film in dichloromethane on a conducting substrate, the modified electrode was continuously cycled in alkaline solution until a steady voltammetric profile was obtained. Although upon electrochemical treatment in basic solutions the nickel–nitrogen tetracoordination of the (NiIIL)n film is probably lost, the nickel species remain entrapped inside the polymeric skeleton and exhibit stable redox behavior resembling that of the nickel hydroxide electrode. This makes it possible to prepare very thin films of nickel‐based modified electrodes. In cyclic voltammetry experiments the Ni‐CME exhibits a pH dependence of the peak potentials typical of the α‐Ni(OH)2/γ‐NiOOH redox process, and a separation between anodic and cathodic peak potentials of 64mV at pH 13.2 and 10 mVs−1. The redox catalysis at Ni‐CMEs of representative compounds that are not easily electrooxidized, such as choline, cadaverine, γ‐amino butyric acid (GABA), benzyl alcohol, and glycine, is demonstrated. The good stability of these nickel‐based modified electrodes makes them attractive in analytical applications.
Development of analytical procedures based on abrasive stripping coulometry and voltammetry for solid state phase microanalysis of natural and synthetic tin‐, arsenic‐, and antimony‐bearing sulfosalts and sulfides of thallium, tin, lead, and silver
Authors: Zhang Song , Meyer Birgit , Moh Günter H. , Scholz Fritz 
Published: May 2005

AbstractAnalytical procedures are described for the solid state phase microanalysis of synthetic and natural tin‐, arsenic‐, and antimony‐bearing sulfosalts and sulfides of thallium, tin, lead, and silver. In these procedures, abrasive stripping voltammetry and coulometry of the solid phases are applied. Trace amounts of the sample compounds were transferred onto the surface of a graphite electrode and the electrochemical reduction or oxidation was followed by voltammetric techniques. The most valuable technique for distinguishing different mineral phases is to record the anodic dissolution voltammograms after a preliminary electrolytic reduction of the sulfides or sulfosalts to the elementary metals which are still confined to the electrode surface. For various compounds an approach was developed in which the ratio of charges consumed during reduction and oxidation of the solid phases is used for unambiguous identification. Coulometric measurements are also used for the determination of the quantitative composition of the solid phases.
Determination of penicillin by triangle programmed coulometric acid–base flow titration in a system incorporating an enzyme reactor
Authors: Fehér Zsófia , Nguyen T. Len , Nagy Géza 
Published: May 2005

AbstractA flow‐through coulometric titration technique is described which can be applied for the determination of a wide variety of compounds. If necessary, the sample can be transformed in the measuring system into a form which can be titrated. Thus an enzyme‐catalyzed reaction can also be used as a sample pretreatment step. In this article a measurement technique and apparatus are described in which an enzyme‐catalyzed reaction is used for the fast and reliable determination of penicillin compounds. The principle of the technique is that an enzyme reactor is built into the sample line of the measurement system used for performing coulometric triangle programmed titrations. One of the components of the reaction mixture leaving the reactor (in this case penicilloic acid) is determined by coulometric acid–base titration. This technique is especially useful for the analysis of large sample series.
Amplified biosensing of alcohol based on biocatalytic accumulation of the mediator
Authors: Wang Joseph , Naser Najih 
Published: May 2005

AbstractA novel strategy for enhancing the sensitivity of alcohol‐dehydrogenase amperometric biosensors, based on biocatalytic accumulation of the mediator, is described. By performing the biochemical/chemical step under open‐circuit conditions, it is possible to accumulate the reduced form of the Meldola blue mediator, prior to the chronoamperometric quantitation of the enriched layer. Such temporal separation of the recognition and transduction events offers a 35‐fold sensitivity enhancement (following a 5‐min accumulation). Factors influencing the response are explored and applicability to various wine samples is illustrated. The new amplification strategy can be extended to biosensors based on other nicotinamide‐cofactor dependent dehydrogenases.
Electrochemical behavior of aromatic amines protected by the nitrobenzenesulfonyl group
Authors: Zanoni Maria V. Boldrin , Stradiotto Nelson Ramos 
Published: May 2005

AbstractThe electrochemical reduction of aniline protected by the 4‐, 3‐, or 2‐nitrobenzenesulfonyl group in N,N‐dimethylformamide (DMF) at a vitreous carbon electrode is reported. The compounds are reduced in three cathodic steps. The first reduction step at about −0.85 V vs. SCE occurs with the formation of an unstable anion radical, which decomposes via NH bond cleavage. Reduction of this sulfonamide anion occurs at −1.16 V for para and meta isomers and at −1.48 V for the ortho isomer. The third cathodic step occurs at higher cathodic potentials. The BH bond cleavage is always the preponderant process. The mechanisms of the reduction are discussed.