bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient production of ethanol by a fermentation system employing temperature profiling and recycle
Authors: Kobayashi Masahide , Ishida Kohji , Shimizu Kazuyuki
Published: May 2005

Based on a mathematical model for ethanol fermentation, the optimal pattern for changing culture temperature to maximize the final ethanol concentration was derived utilizing the maximum principle. The optimal temperature scheme started cultivation at 30°C (upper limit) descending later to 20°C (lower limit). The effects of culture temperature and ethanol concentration on growth and ethanol formation were studied by controlling the ethanol concentration at a specified level using recycle with a hollow fiber module. A novel method of operation was also investigated where temperature was initially kept at 30°C and ethanol concentration was controlled low simultaneously by the recycle system. The culture temperature was eventually lowered and the draw‐off rate through the hollow fiber stopped. This operation was shown to yield significant improvement for efficient ethanol production.
Dehydration of ortho‐boric acid in a three‐phase bubble column reactor operating at low pressure
Authors: Kang Yong , Shim Jung S. , Cho Soo H. , Choi Myung J. , Lee Kyu W.
Published: May 2005

This study investigates the applicability of the bubble column as a reactor to perform the dehydration of ortho‐boric acid efficiently and economically. The effects of operating conditions such as reaction time, temperature, gas flow rate, particle size and solid content in the slurry phase on the fractional conversion of the reaction have been determined, and the performance of the three‐phase bubble column reactor operating at low pressure (92 kPa) has been discussed. It can be noted from this study that the reaction time has been reduced and the particle size and solid content which are required in the slurry phase for favourable fractional conversion have been increased in the bubble column reactor in comparison with those in the continuous stirred tank reactor. The reaction could be described by means of a fluid–solid heterogeneous reaction model.
Preparation and gas separation performance of silicone‐coated polysulfone membranes
Authors: Marchese José , Ochoa Nelio , Pagliero Cecilia
Published: May 2005

Composite membranes (CM) were prepared by coating the dense surface of different asymmetric polysulfone flat membranes (AM) with a solution of silicone rubber polymer. The surface porosity (ε) of the dense skin AM samples varied between 4 × 10−5 and 1·5 × 10−8, with an average mean pore size between 0·10 and 0·07 μm. Scanning electron microscopy (SEM), gas permeation experiments (H2, N2, CH4, CO2) and a simple resistance model were used for the determination of structure‐permeability relationships. This study indicates that the CM prepared with polysulfone AM having ε < 3 × 10−7, coated with a concentration of 6% silicone solution and a contact time of 1 min, has the best gas separation performance, with selectivities very close to the intrinsic polysulfone selectivities.
The preparation of activated carbons from chips of oil palm trunk catalysed by ZnCl2/CO2: Surface area and porosity studies
Authors: Hussein Mohd Zobir , Zainal Zulkarnian , Ibrahim Ramli , Kheong Kohr K. , Muhammad Badri
Published: May 2005

Activated carbons were prepared by ZnCl2/CO2 activation of the chips of oil trunk. The surface area and the nature of the porosity of the resulting activated carbons were found to be related to the concentration of the impergnated zinc solution to the precursor. It is possible to prepare activated carbons with a fairly high surface area (more than 2000 m2 g−1) from chips of oil palm trunk.
Surface tension as a limiting factor for aerobic n‐alkane biodegradation
Authors: Setti Leonardo , Pifferi Pier Giorgio , Lanzarini Gaetano
Published: May 2005

A new mathematical model for n‐alkane biodegradation in crude oil, heavy oil and paraffinic mixtures is described. The pattern of n‐alkane degradation as a function of the inverse of hydrocarbon chain length reported in this paper can be considered as general behaviour for many aerobic n‐alkane biodegradation processes. A new interpretation of n‐alkane biodegradation as a function of surface tension, is given. A mathematical expression was obtained starting from the degradation values of n‐alkane and relative surface tension, which is a parameter independent of fermentation conditions. An interesting parameter, b, was identified which represented the accelerating conversion factor for n‐alkane biodegradation. The findings suggested that the n‐alkane biodegradation. The findings suggested that he n‐alkane biodegradation rate may be affected by the fermentation condition (agitation, aeration, etc.) and by the strain of microorganism, while the behaviour pattern of n‐alkane degradation was essentially linked to the substrate characteristics (molecular structure, molecular weight and density).
Metal ion concentration, time, and pH dependence of metal ion binding to a transferrin metalloprotein affinity chromatography (MAMC) matrix
Authors: Cannell Kevin P. , Vincent John B.
Published: May 2005

The adsorption of transition metal, lanthanide, and actinide ions to avotransferrin (conalbumin) immobilized to sepharose (via the cyanogen bromide method) has been examined. Adsorption of ions as a function of time and adsorption isotherms at pH 8 have been determined and analyzed using the Freundlich model, distribution coefficients between the pH vales 2 and 9 have been measured. The results indicate that immobilization of the protein has little effect on its interactions with metal ions compared with the protein in solution, and important prerequisite for use of this matrix in metalprotein affinity metal homatography (MAMC).
Removal of copper from industrial wastewater by raw charcoal obtained from reeds
Authors: Khalfaoui Brahim , Meniai Abdessalem H. , Borja Rafel
Published: May 2005

In the present paper, we study the adsorption of Cu2+ from industrial wastewater and aqueous solution at 293 K, by a by‐product of activated carbon (raw charcoal) obtained from reds. A Method of preparation of raw charcoal was established and the main adsorption characteristics of metal ions were examined, as well as the static and dynamic conditions of the adsorption process. The adsorbent properties of the charcoal used were also studied. The presence of other metal ions in the solution decreases the adsorption capacity for copper, and the chemical nature of the charcoal surface and metal ions have a great significance for the adsorption process. The area of charcoal was about 400 m2 g−1 at a carbonization temperature of 973 K.
Electrosynthesis of β‐methylpentadecanedioic acid dimethyl ester
Authors: Zhongcheng Zhang , Jiali Liu , Yuxia Shang
Published: May 2005

β‐Methylpentadecanedioic acid dimethyl ester (I) was synthesized electrochemically by Kolbe reaction using β‐methylglutaric acid monomethyl ester (II) and α,ω‐dodecanedioic acid monomethyl ester (III) as starting materials in MeOH solution. Electrolysis was carried out ofr about 4–5 h, when solution pH ≥ 7, followed by extraction with petroleum ether and distillation to obtain a colourless oily product (I) The minimum production cost occurred when the mole ration of II to III was 1:1·38 and unreacted III could be recovered. The product synthesized (I) completely met the requirement of artificially synthesized musk.
Catalytic wet oxidations of phenol‐ and p‐chlorophenol‐contaminated waters
Authors: Chang Chiehmign J. , Li Shiow‐Shya , Ko Ching‐Ming
Published: May 2005

The rate constant and activation energy of liquid‐phase oxidation catalyzed by CuSO4 · 5h2O, and Co2O3, were found for synthesized wastewaters containing 1000 mg dm−3 phenol and 1500 dm−3 p‐chlorophenol, respectively. Among the catalysts, CuSO4 · 5H2O was demonstrated to be the most effective in reducing the concentration of phenols in wastewaters. The effects of oxygen flow rates and temperatures on the oxidation efficiency were also discussed. The analysis of total organic carbon on the end products after oxidations showed that the liquid phase contained only 10% of intermediate products. Oxidation at different pH values suggested that phenols could be favourably destroyed in an alkaline medium.
Use of a genetic algorithm in the development of a synthetic growth medium for Arthrobacter simplex with high hydrocortisone Δ1‐dehydrogenase activity
Authors: Weuster‐Botz D. , Pramatarova V. , Spassov G. , Wandrey C.
Published: May 2005

The production process for Arthrobacter simplex high specific hydrocortisone Δ1‐dehydrogenase activity and biomass yield (full experimental plan: 1·5 × 1014 experiments). The specific hydrocortisone Δ1‐dehydrogenase activity was improved by a vector of 4·5 to 1800 U g−1. With the optimized medium composition in a stirred tank reactor for batch production of A. simplex, a specific hydrocortisone Δ1‐dehydrogenase activity of 2000–3000 U g−1 dry biomass was achieved depending on harvest time (previously reported data: 18–37 U g−1).
Quantitative HPTLC determination of prostaglandin E1
Authors: Luitjens K.‐D. , Funk W. , Rawer P.
Published: May 2005

Direct in situ determination of PGE1 in dioxane/water (1:1) at concentrations between 50 μg/ml and 1 mg/ml is described. HPTLC of PGE1 was carried out on HPTLC Kieselgel 60 o.F. plates; application (200 nl) was with a Nano‐Appllcator and ethyl acetate/formic acid (400:5, v/v) served as mobile phase. The spots were located by dipping the plates into a 3% cupric acetate solution in 15% aqueous phosphoric acid, followed by heating at 120°C for 15 min. The plates were then evaluated directly at λ = 345 nm by chromatogram spectrometry. The coefficient of variation is 3.6%.
Fourier transform ion mobility spectrometry of barbiturates after capillary gas chromatography
Authors: Eatherton R. L. , Siems W. F. , Hill H. H.
Published: May 2005

This paper demonstrates a novel operating mode of an ion mobility detector (IMD) for obtaining both qualitative and quantitative data after capillary gas chromatographic separation of 5,5′‐disubstituted barbiturates. Using a recently developed time dispersive Fourier transform method for ion mobility spectrometry, complete ion mobility spectra could be obtained for each component in the chromatogram. This type of spectra can be used for providing qualitative information on unknown compounds or for selecting the proper detector conditions needed when operating in the continuous mobility monitoring mode.

In this study each of the five barbiturates investigated produced a Fourier transformed ion mobility spectrum containing one major product ion. When drift times corresponding to those of the product ions measured in the FT mode were monitored continuously, selective chromatographic detection of the barbiturates was achieved. In one case even isomers could be differentiated based on mobility characteristics.
Capillary supercritical fluid chromatography with ultraviolet multichannel detection of some pesticides and herbicides
Authors: France J. E. , Voorhees K. J.
Published: May 2005

The useful combination of capillary supercritical fluid chromatography with ultraviolet multichannel detection is demonstrated by the analysis of selected pesticides and herbicides. In this application the advantages of compound identification by ultraviolet spectrometry are appended to the separating capability of capillary supercritical fluid chromatography. A pseudo oncolumn detection approach is used. Compromises from the theoretically ideal conditions for both capillary SFC and the multichannel UV detector are made to achieve a practical interfacing of the chromatographic and spectrophotometric techniques. Detection limits are at the low nanogram levels.
Determination of methylated dibenzothiophenes in environmental sarnples by on‐line HPLC‐CGC
Authors: Berthou F. , Dreano Y.
Published: May 2005

Concurrent solvent evaporation with a loop‐type interface was used for on‐line HPLC‐CGC in the analysis of methylated dibenzothiophene (DBT) isomers in oil samples. The chromatographic behavior of 20 methyl DBT's was studied by HPLC on an aminopropylsilane DBTA phase and by GC on a selective methyl‐phenylsilicone phase. That provided a method for analyzing by GC‐flame photometric detection, the individual components of the DBT family, previously picked out of the crude oil matrix by HPLC. The GC oven temperature was shown to be critical during HPLC eluent introduction into the GC pre‐column. Too high a temperature induced a severe broadening of early eluted peaks whereas a temperature too close to the boiling point of the liquid at the inlet pressure induced double peaks. Optimized conditions were retained on this basis and may be used for the analysis of other families of polyaromatic hydrocarbons.
Computer‐aided selection and optimization of chromatographic columns and conditions for multicolumn analysis procedures
Authors: Villalobos Richard , Annino Raymond
Published: May 2005

Clearly, the usefulness of a computer‐aided column design program will depend on its ability to predict quickly and accurately, a design which will yield chromatograms closely approximating those obtained experimentally. Such a computer model for designing and specifying operating conditions for optimum performance of either single or serially coupled columns with different stationary phases is described herein. Tests have been performed in order to verify the accuracy of the model.

In addition to single column optimization and the design of column combinations which can be used to achieve separations difficult or impossible on a single phase alone, the model has proven quite useful as an aid to the design and development of multicolumn analysis procedures that involve critical timing of valve‐switching sequences.
Quantitative determination of sulfur compounds in FCC gasolines by AED. A study of the effect of catalyst type and catalytic conditions on sulfur distribution
Authors: Albro Thomas G. , Dreifuss Peter A. , Wormsbecher Richard F.
Published: May 2005

The identification and quantification of sulfur‐containing compounds in gasoline has become an area of interest because of impending legislation regulating total sulfur levels in these fuels. To study the effects of catalyst type and catalytic conditions on gasoline sulfur distribution, a method has been developed employing both the compound‐independent and element‐specific response of the atomic emission detector (AED). Calibration and quantification can be accomplished even where standards are not available, owing to the nature of the AED response.

Compounds were separated on a thick film polydimethylsiloxane column. An external calibration curve was applied to the area responses of individual sulfur components in the sulfur chromatogram, and the concentrations of each were calculated. Summation of these sulfur concentrations over the gasoline range yields the total sulfur content of the gasoline.

The method is applicable to the determination of these compounds in raw crude oils, finished gasolines, fluid cracking catalyst (FCC) unit gasolines, and fluid catalytic cracking “model” compound studies. A prefractionating column was employed to remove heavy (>C13) materials; prefractionation is not, however, necessary for distilled or commercial gasoline samples. Detection limits, linearity, detector stability, and accuracy are discussed.
High resolution gas chromatographic method for determination of Robusta coffee in commercial blends
Authors: Frega Natale , Bocci Fabio , Lercker Giovanni
Published: May 2005

The unsaponifiable lipid fractions extracted from Arabica and Robusta coffee samples were analyzed by high resolution gas chromatography (HRGC) in a polar column with a thermally stable stationary phase (TAP, Chrompack). Certain characteristic ratios among diterpenic alcohols were found to permit measurement of the amount of Robusta blended with Arabica coffee, given a minimum content of 5–10%. Determination does not appear to be influenced by geographic origin of produce or even by decaffeination.
Isomeric composition of the ester fraction from epicuticular waxes of Festuca arundinacea Schreb
Authors: Tava Aldo , Cunico Cristina , Cremona Roberta , Piccinini Emiliana
Published: May 2005

The ester portion of epicuticular waxes of tall fescue (Festuca arundinacea Schreb.) is composed of mixtures of homologous series of fatty acids esterfied with fatty alcohols. GC analyses of natural esters gave rise to the separation of several compounds of different chain length. To identify and quantify individual components in the mixture, GC/MS analyses were carried out, and the mass spectra of each peak were recorded and analyzed for characteristic ions. This approach permitted a comparison with data obtained from classical methods using GC analysis of acid and alcohol moieties obtained by hydrolysis.
Reversed phase HPLC coupled on‐line to GC by the vaporizer/precolumn solvent split/gas discharge interface; analysis of phthalates in water
Authors: Hyötyläinen Tuulia , Grob Konrad , Biedermann Maurus , Riekkola Marja‐Lüsa
Published: May 2005

Reversed phase liquid chromatography (RPLC) was coupled on‐line to gas chromatography (GC) via the vaporizer chamber/preco‐lumn solvent split/gas discharge interface outlined recently. Water‐containing eluents were driven into a vaporizer chamber at 300°C by the LC pump. The Vapors were removed through an early vapor exist by the carrier gas. Solvent/solute separation occurred in hte retaining precolumn. Special attention was paid to the parame‐ters determining the losses of the most volatile compounds. The oven temperature during transfer was lowered close to the dew point of the eluent (the temperature at which recondensation occurs) in order to maximise the retention power of the retaining precolumn. The dew point depends on the transfer rate, the gas flow rate, and the gas inlet pressure. Sometimes even better retention of the vola‐tiles was observed at temperatures below the dew point, i.e. despite partial reconsideration. The method was applied to the analysis of phthalates in drinking and surface waters. The detection limits, using MS, were 5–10 ng/l.
Recombinant human secretory phospholipase A2: Purification and characterization of the enzyme for active site studies
Authors: Stadel J. M. , Jones C. , Livi G. P. , Hoyle K. , Kurdyla J. , Roshak A. , McLaughlin M. M. , Pfarr D. A. , Comer S. , Strickler J. , Bennett C. F. , Marshall L.
Published: May 2005

A secreted form of phospholipase A2 (PLA2) is thought to play an important role in inflammatory diseases. To characterize this enzyme the cDNA encoding a low molecular weight PLA2 was cloned from a human placental cDNA library. The cDNA encoding the human PLA2 was subcloned into an expression vector and subsequently transfected into Chinese hamster ovary (CHO) cells. A stable CHO cell clone, secreting ca I mg/L of recombinant PLA2 into the medium, was scaled up in culture to 180L. The recombinant enzyme was purified from the cell supernatant to apparent homogeneity by a novel procedure combining adsorption to poly(vinylidene difluoride) membranes, ion exchange chromatography and size exclusion chromatography. The final recovery of PLA2 activity was 58%. A direct comparison between the purified recombinant human PLA2 and PLA2 purified from human synovial fluid, including molecular weight, antigenicity, ionic dependence, substrate specificity and sensitivity to know PLA2 inhibitors, indicated that the two enzymes exhibit identical biochemical properties. These results show that the recombinant PLA2 can be efficiently expressed and purified in sufficient quantities to characterize the enzyme active site, to aid in the rational development of PLA2 inhibitors as potential anti‐inflammatory drugs, and to investigate further the role of PLA2 in inflammatory disease.
Spectrofluorimetric study of the intermolecular complexation of monoclonal antibodies with the high potency sweetener N‐(p‐cyanophenyl)‐N′‐(diphenylmethyl)guanidineacetic acid
Authors: Droupadi P. R. , Anchin J. M. , Meyers E. A. , Linthicum D. S.
Published: May 2005

Molecular complexation between a set of five monoclonal antibodies (MAbs) and a N,N′,N″‐trisubstituted guanidinium sweetner (TGS) was studies by monitoring the intrinsic fluorescence of the MAbs. Changes in the emission spectral properties of the MAbs were found to be related to the tryptophan residues in the antibody complementarity determining regions (CDRs). Two of the MAbs, NC10.10 and NC10.8, showed fluorescence quenching and hypsochromic (blue) shifts in the emission maxima upon complexation with the TGS ligand. Experiments with three other MAbs, NC6.8 and NC2.3, revealed only monotonic fluorescence quenching. The association constants obtained by spectroscopic techniques for the different MAb‐TGS complexes were found to be comparable with those determined using a conventional RIA. The thermodynamic parameters of the MAb‐TGS complexation were also examined. The intermolecular complexation was found to be exothermic for four of the five MAbs in this study. However, MAb NC2.3 was found to be an exception, in that it was associated with a small positive enthalpic change. This type of Spectrofluorimetric analysis can aid in the identification of interactive residues and molecular dynamics involved in TGS recognition by this set of MAb. Such information may prove useful in understanding the molecular recognition motifs responsible for the intense taste properties of high potency guanidine sweeteners.
Specific effect of corticoids on acetylcholine receptor expression in rat skeletal muscle cell cultures
Authors: Vilquin J.‐T. , Braun S. , Labouret P. , Zuber G. , Tranchant C. , Poindron P. , Warter J.‐M.
Published: May 2005

The potential effect of different classes of steroids on the expression of acetylcholine receptors (AChR) was studied in different primary cultures of newborn‐rat skeletal muscle cells. Comparison among three techniques for preparing newborn skeletal muscle cells showed that these systems were equivalent to study AChR expression. Only corticoids stimulated myogenesis as a twofold increase in AChR expression indicated. Among the corticoids, the glucocorticoids were the more potent, whereas the mineralocorticoid aldosterone had less marked effect. The sex hormones progesterone and testosterone partially blocked these effects, without inducing any significant effect when given alone. The steroids tested differed in efficacy in correlation with their different chemical structures. Among the glucocorticoids a clear structure‐activity relationship could be established. These results emphasize the specificity of corticoid action on muscle cells and suggest an explanation for the effects induced by glucocorticoids used in treating human muscular or neuromuscular diseases.
Origin of cells in contact with the growth cones of embryonal peripheral nerves and histochemical detection of nonspecific cholinesterase activity in quail‐chick and chick‐quail chimeras
Authors: Haninec P. , Dubový P.
Published: May 2005

The types of cells contacted by growth cones were examined in chick‐quail and vice versa chimeras. Simultaneously, the presence of nonspecific cholinesterase (nChE) was monitored in developing peripheral nerves of these embryos. In all the chimeras studied, the growth cones were in contact with both Schwann cell progenitors and mesenchymal cells of the limb bud. This observation implies that the growth cones may obtained guidance cues directly from the mesenchymal cells of the limb bud. Schwann cell progenitors as well as mesenchymal cells in contact with growth cones were capable to produce nChE molecules. The reaction product indicating nChE activity was localized on the outer surface of the plasma membrane of both types of cells in contact with growth cones. However, mesenchymal cells forming the “primitive perineurium” were devoid of the reaction product on their plasma membrane. We conclude that with exception of classic adhesive molecules the process of axonal guidance can be mediated by nChE molecules.
Miniature endplate potentials induced by ammonium chloride, hypertonic shock, and botulinum toxin
Authors: Vautrin J.
Published: May 2005

Intracellular recordings were made at the neuromuscular junction (NMJ) of the mouse diaphragm to study alteration of miniature endplate potential (MEPP) amplitude and rise time after different treatments. Following either hyperosmotic shock or 3 to 5 min of incubation in 10 to 50 mM ammonium chloride (NH4Cl) (replacing NaCl, a treatment which is known to raise intracellular pH) MEPP frequencies increased and the amplitudes of. MEPPs decreased. These treatments as well as type A botulinum toxin (BoTx) gradually prolonged the rising phase of some MEPPs, which increased their time‐to‐peak (slow‐MEPPs; Vautrin and Kriebel: Neuroscience 41:71–88, 1991) and increased eventually their amplitude. Fasciculation after hyperosmotic shock or during NH4C1 challenge was blocked by D‐tubocurarine and was due to large slow‐MEPPs that reached threshold for the muscle fiber action potential. The development of fasciculation provided the time course for the development of giant‐MEPPs. Increased frequency of giant MEPP is accompanied by a block of the nerveevoked muscle contraction. Effects of BoTx on spontaneous release were functionally antagonized either by NH4C1 or hyperosmotic shock. NH4C1 delayed BoTx blockage of bell‐MEPPs. Data suggest that BoTx alters the formation of transmitter packets gradually but similarly to other treatments which increase incidence of skew‐MEPPs.
Nicotinic receptors of rat lymphocytes during adjuvant polyarthritis
Authors: Maslinski W. , Laskowska‐Bozek H. , Ryzewski J.
Published: May 2005

Resting rat lymphocytes and thymocytes express specific [3H]nicotine binding sites with Kd values 7.5 and 10 nM, respectively. Resting T lymphocytes express 5–7 times as many binding sites (1,500/cell) as do unfractionated thymocytes (250/cell), suggesting that only a subset of thymocytes express nicotinic binding sites. Neither macrophages nor B cells bear nicotinic receptors. [3H]nicotine binding to lymphocytes is competitively inhibited in the presence of the cholinergic agonist carbamylcholine with IC50=100 μM. The number of receptors expressed on draining lymph node lymphocytes is upregulated during the course of adjuvant induced polyarthritis: maximum of [3H]nicotine binding is observed at day 21 of the disease with a subsequent decline reaching basal level at day 36. These results show the presence of [3H]nicotine binding sites on T lymphocytes and suggest their involvement in the later immune phase of adjuvant induced polyarthritis.
GnRH‐Associated peptide (GAP) is present in the rat striatum and affects the synthesis and release of dopamine
Authors: Gobert A. , Guibert B. , Lenoir V. , Kerdelhue B. , Leviel V.
Published: May 2005

A possible interference of the GnRH‐associated peptide (GAP) with the metabolism of dopamine in the rat striatum was investigated. The presence of the precursor of the peptide in this central region of dopaminergic terminals was first evidenced using specific RIA. The action of GAP on dopamine release was investigated in the caudate nucleus using the local superfusion with a push‐pull cannula supplied with an artificial CSF containing the Fitiated precursor of dopamine ([3H]tyrosine). Addition of GAP (1 μM) to the superfusing fluid resulted in an increase of the release of the newly synthesized dopamine without a significant modification of the total amine release. In situ neutralization of GAP by addition in the CSF of a rabbit serum containing antibodies directed against the GAP produced opposite effects evidencing a tonic function for this peptide. In addition to the increased specific activity of the dopamine released during GAP treatment, the alterations observed in the efflux (and the specific activity) of dihydroxyphenyl acetic acid and the activation of dopamine synthesis obtained in vitro in striatal slices in the presence of GAP led us to conclude that the GAP system could be considered as a positive control of dopamine synthesis.
Common sequence on distinct Vβ genes defines a protective idiotope in experimental encephalomyelitis
Authors: Vainiene M. , Gold D. P. , Celnik B. , Hashim G. A. , Vandenbark A. A. , Offner H.
Published: May 2005

Synthetic TCR peptides expressed by encephalitogenic T cells can induce both cellular and humoral responses that protect against experimental encephalomyelitis. In the Lewis rat, encephalitogenic T cells predominantly express Vβ8.2, and a peptide in the CDR2 region representing residues 39–59 could both protect against and treat experimental autoimmune encephalitis (EAE). Similarly, the homologous and cross reactive 39–59 peptide from Vβ8.6 expressed by an EAE‐protective clone also had protective and therapeutic activity against EAE. The consensus sequence between the Vβ8.2 and Vβ8.6 peptides, which included residues 44–54, was postulated to contain the protective idiotope. In this report, we demonstrate that this peptide, designated Vβ8‐44–54, has comparable activity to the longer peptides for treating both active and passive EAE. Similar to the longer Vβ8.2‐39–59 peptide, the Vβ8‐44–54 peptide stimulates protective TCR peptide‐specific CD4 +, CD8dim T cells restricted by MHC I. We also report for the first time the recovery of Vβ8‐44–54 reactive T cells that express a variety of Vβ genes in their T‐cell receptor (TCR), including Vβ4, 8, 10, 12, 15, 17, 19, and 20. Taken together, these data establish that the Vβ8‐44–54 sequence constitutes an important autoregulatory idiotope in EAE. Moreover, the heterogeneity observed in the TCR expressed by anti‐Vβ8‐44–54 T cells suggests that the mechanism that produces biased V gene use in response to myelin basic protein (BP) is distinct from that which shapes the V gene repertoire of the regulatory T cells.
Transferrin receptor expression in myelin deficient (md)rats
Authors: Roskams A. J. , Connor J. R.
Published: May 2005

The question of iron regulation in the brain is the subject of increasing interest as the evidence continues to accumulate that a loss of brain iron homeostasis plays a significant role in some neurodegenerative diseases. Most cells acquire iron through a specific receptor mediated process involving transferrin, the iron mobilization protein. It appears that in the brain, endothelial cells, neurons, and oligodendrocytes express the transferrin receptor. This study uses a strain of rats (myelin deficient, md) in which oligodendrocytes fail to mature, and examines the consequences of this genetic defect on the expression of the transferrin receptor in the brain. The affinity of transferrin for its receptor is similar between the cerebral cortex and cerebellum in both the normal and myelin deficient rats (Kd = 7.8–10.6 nM). The transferrin receptor density is normally 2–3 times higher in the cerebellum than in the cerebral cortex. In the myelin deficient rat strain, the density of the transferrin receptor is decreased in both the cerebrum (56%) and cerebellum (70%) compared to the littermate control animals. Because oligodendrocytes are the only cell type affected in this mutant, the results suggest that these cells are responsible for a considerable amount of the transferrin receptors that are expressed in the brain (excluding the endothelial cell contributions). These observations are consistent with the existing literature stating that oligodendrocytes are responsible for the majority of transferrin and transferrin mRNA which is expressed in the brain, and support the working hypothesis that imbalances in brain iron homeostasis, particularly during development, are associated with myelin disorders.
Reactive microglia/macrophages phagocytose amyloid precursor protein produced by neurons following neural damage
Authors: Shigematsu K. , McGeer P. L. , Walker D. G. , Ishii T. , McGeer E. G.
Published: May 2005

Kainic acid lesions of rat striatum caused an elevation of amyloid precursor protein (APP) immunoreactivity in neurons and neurites, some of which were then phagocytosed by reactive microglia/macrophages. Immunoexpression of APP was observed in neurites and neurons 1 day after the kainic injection. Four days after lesioning, immunoreactivity was still concentrated in thick and distorted neurites, but it began to appear in microglia/macrophages and in the tissue matrix. The cells were identified as microglia/macrophages by the phenotypic markers Ia (OX6), leukocyte common antigen (OX1), C3bi receptor (OX42), and macrophage marker (EDI). They were negative for the astrocytic marker glial fibrillary acidic protein (GFAP). APP immunoreactivity in these phago‐cytic cells was most prominent between 1 week and 1 month postlesioning. No extracellular amyloid fibrils were detectable. These results suggest that APP production is rapidly upregulated in damaged neurons and accumulates in degenerating axons. However, phagocytosis of APP by reactive microglia/macrophages in this rat model does not result in production of Alzheimer type amyloid deposits.
Effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons
Authors: Ekström P. A. R. , Bergstrand H. , Edström A.
Published: May 2005

The effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons were tested. Regeneration of crush‐injured nerves for 8 days in serum‐free medium was inhibited by staurosporine (100 nM) and H‐7 (100 μM), which are both known to inhibit protein kinase C. With the use of a compartmented culture system it could be shown that H‐7 exerted both local (outgrowth region) and central (ganglia) effects, the latter being more pronounced. The local effects could be due to reduction of Schwann cell proliferation by H‐7. Immunohisto‐chemistry demonstrated the presence of protein kinase C in neuronal cell bodies but not in axonal processes. Proliferation of Schwann cells was accompanied by increased protein kinase C immunoreactivity at the site of injury. H‐7 caused a selective inhibition in the incorporation of radioactive phosphate into one 74 kDa protein of both ganglia and nerve but also a more general decrease in protein labelling. The results show that protein phosphorylations, possibly mediated by protein kinase C, are involved in regeneration‐related mechanisms operating at both local and central levels in the adult frog sciatic sensory axons.
Interferon‐γ‐Like immunoreactivity in sensory neurons may influence the replication of sendai and mumps viruses
Authors: Eneroth A. , Andersson T. , Olsson T. , Örvell C. , Norrby E. , Kristensson K.
Published: May 2005

Rat dorsal root ganglia in tissue culture, which contain an interferon‐γ (IFN‐γ)‐like immunoreactive subpopulation of neurons, were infected with paramyxoviruses. Sendai virus caused a substantial neuronal lysis, while the RW strain of mumps virus caused a much less pronounced nerve cell loss. Early during infection, the subpopulation of IFN‐γ‐like immunoreactive neurons was less susceptible to mumps virus. Virus antigen was rapidly lost from surviving IFN‐γ‐like positive neurons infected with Sendai virus, while this remarkable self‐curing effect occurred in both nerve cell populations at later time points after mumps virus infection. By quantitative enzyme‐linked immunosorbent assay (ELISA) technique, increased levels of “neuronal IFN‐γ” were recorded at 10 hr and 30 hr after infection with Sendai and mumps virus, respectively. This study indicates a role for the neuronal IFN‐y‐like molecule in determining the outcome of a viral infection in sensory ganglia.
Focal, extracellular recording of slow miniature junctional potentials at the mouse neuromuscular junction
Authors: Vautrin J. , Kriebel M. E.
Published: May 2005

Miniature endplate potentials (MEPPs) with slow rising phase can be attributed either to burst of transmitter releases or to distortion of conduction from remote releasing sites. The spontaneous activity of neuromuscular junctions recorded extracellularly at mouse diaphragms using sharp electrodes was analyzed to test these two hypotheses. The miniature Junctional potentials (MEJPs) frequencies observed intracellularly as compared to MEPP frequency measured intracellularly in controls indicate that most events recorded extracellularly are induced by the presence of the electrode. All types of MEPPs (bell‐MEPPs, skew‐MEPPs, slow‐, and giant MEPPs) previously described with intracellular recording methods (Vautrin and Kriebel, Neuroscience 41:71–88, 1991) were observed extracellularly and showed similar characteristics. This means that the presynaptic and postsynaptic zones that generate these synaptic events are restricted within areas of a few micrometers squared of synaptic contact. Long rise times of extracellularly recorded synaptic spontaneous events may be explained by multiple transmitter releases at intervals shorter than the rise time of individual events, which postsynaptic responses fuse into a single peak.
Implication of glucocorticoid receptors in the stimulation of human glioma cell proliferation by dexamethasone
Authors: Langeveld C. H. , van Waas M. P. , Stoof J. C. , Suianto W. , de Kloet E. R. , Wolbers J. G. , Heimans J. J.
Published: May 2005

Dexamethasone is frequently used in the therapy of brain tumor patients. We investigated the effect of dexamethasone on the proliferation of three short‐term and four established human glioma cell lines in vitro, using a microculture tetrazolium assay to determine growth rates. In one short‐term culture and in one established cell line dexamethasone consistently stimulated the proliferation in concentration‐dependent way. The proliferation was maximally enhanced at a concentration of approximately 0.1 μM. In these two cell lines a relatively high level of glucocorticoid receptors was present, whereas low levels of glucocorticoid receptors were found in the other cell lines. In addition, we demonstrated that the stimulatory effects of dexamethasone on the proliferation of the glioma cell lines can be antagonized by the antiglucocorticoid RU38486. The results demonstrate unequivocally that the glucocorticoid receptor plays a role in the growth stimulating effect of dexamethasone.
Subcellular distribution of ubiquitin–protein conjugates in the hippocampus following transient ischemia
Authors: Hayashi T. , Takada K. , Matsuda M.
Published: May 2005

Ubiquitin–protein conjugates in the hippocampus were analyzed by immunoblotting with a monoclonal anti‐ubiquitin antibody. In the CA1 region, Triton X‐100 insoluble ubiquitin–protein conjugates increased after 24 hr following 20 min of ischemia. When the total hippocampi were fractionated subcellularly, ubiquitin–protein conjugates increased in the particulate, especially in the mitochondrial fraction. The ubiquitin–protein conjugates were solubilized by SDS, or were partially solubilized by urea. The results indicate that insoluble ubiquitin–protein conjugates increase after ischemia.
Nerve growth factor‐stimulated calcium uptake into PC12 cells: Uniqueness of the channel and evidence for phosphorylation
Authors: Nikodijevic B. , Guroff G.
Published: May 2005

Nerve growth factor stimulates the uptake of radioactive calcium into PC12 cells. This stimulation is inhibited by low concentrations of dideoxyforskolin or staurosporine, and by high concentrations of nifedipine or cadmium. On the other hand, neither dideoxyforskolin nor staurosporine inhibited the stimulation of calcium uptake caused by BK‐8644 or adenosine triphosphate (ATP). Nickel inhibited only the effect of ATP on calcium uptake, and actually stimulated the effects of either BK‐8644 or nerve growth factor.

Down‐regulation of L‐calcium channels by BK‐8644 blocked the subsequent stimulation of calcium uptake by this agent, but not the stimulation by nerve growth factor. Conversely, pre‐treatment of the cells with nerve growth factor inhibited the subsequent stimulation of calcium uptake by nerve growth factor, but not the stimulation by BK‐8644. The effects of BK‐8644 and nerve growth factor on calcium up‐take were additive, as were the effects of nerve growth factor and ATP.

Phosphatase 2A inhibited the effect of nerve growth factor on calcium uptake, but did not influence the action of BK‐8644. On the other hand, cal‐cineurin inhibited the effect of BK‐8644 on calcium uptake, but potentiated the action of nerve growth factor. Calmidazolium or fluphenazine also inhibited the effect of nerve growth factor on calcium uptake, but okadaic acid stimulated it.

A comparison of the effects of these inhibitors on the actions of various calcium channel agonists shows that the channels on which the action of nerve growth factor is exerted are different than either the L‐type calcium channels or the ATP‐activated calcium channels. These data also indicate that the action of nerve growth factor is mediated by phosphorylation of some component of the nerve growth factor‐sensitive calcium channel.
Expression of heat shock genes (hsp70) in the rabbit spinal cord: Localization of constitutive and hyperthermia‐inducible mRNA species
Authors: Manzerra P. , Brown I. R.
Published: May 2005

We have previously reported that hyperthermia induces the expression of a heat shock gene in the rabbit brain (Sprang and Brown, Mol Brain Res 3:89–93, 1987). Striking regional and cell type differences in the pattern of induction of the hsp70 mRNA were noted. Tissue injury also induces the rapid induction of hsp70 mRNA in the mammalian brain (Brown et al., Neuron 2:1559–1564, 1989). In the present study, in situ hybridization with 35S‐Iabelled riboprobes specific for constitutive and inducible hsp70 mRNA species was employed to investigate the effect of fever‐like temperatures on hsp70 gene expression in the rabbit spinal cord. Expression of constitutive hsp70 mRNA was detected in large motor neurons of both control and hyperthermic animals. Within 1 hr after hyperthermia, a massive induction of inducible hsp70 mRNA was noted in fibre tracts of the spinal cord, a pattern consistent with a strong glial response to heat shock. Induction was not observed in the large motor neurons.
Expression of genes encoding receptors for IgG (FcRIII) and for C3b/C4b (Crry) in rat sciatic nerve during development and wallerian degeneration
Authors: Vedeler C. A. , Conti G. , Bannerman P. , Pleasure D.
Published: May 2005

Northern blots were used to examine the expression of genes encoding receptors for IgG (FcRIII) and for C3b/C4b (Crry) in rat sciatic nerve during development and Wallerian degeneration. Steady state levels of FcRIII (1.4 kb) and Crry (1.9 and 2.1 kb) mRNAs were higher in adult rat nerves than in 6 day and 21day postnatal rat nerves, indicating that the expression of these receptors is developmentally regulated. The FcRIII and Crry cDNA probes also hybridized with total RNA from 3 day old rat Schwann cells and from adult rat peritoneal macrophages. The size of the FcRIII mRNA expressed by cultured Schwann cells (1.6 kb) differed from that expressed by peritoneal macrophages (1.4 kb); the two may be splice variants of one transcript or products of related genes. Peritoneal macrophages contained approximately 100 times higher FcRIII mRNA levels than Schwann cells. In contrast, steady state levels of both 1.9 and 2.1 kb Crry mRNAs were similar in cultured Schwann cells and macrophages. Nerve transection induced a generalized increase in the level of sciatic FcRIII mRNA (1.4 kb) 3 days post‐surgery, whereas he level of Crry mRNA was increased only in the nerve segment immediately to the cut. The increase of FcRIII mRNA that occurred in Wallerian degeneration was most likely due to infiltration of macro‐phages, as FcRIII mRNA‐positive macrophages were demonstrated in the degenerating nerves by in situ hybridization. FcRIII mRNA‐positive macrophages were not found in normal nerve. The functions of FcRIII and Crry in peripheral nerves are uncertain, but they may be of significance in phagocytosis, antibody‐dependent cellular cytotoxicity, and in local immune regulation.
Inhibition of nerve growth factor‐stimulated neurite outgrowth by methylamine‐modified α2‐macroglobulin
Authors: Koo P. H. , Liebl D. J.
Published: May 2005

α2‐Macroglobulin (α2M) is a rather ubiquitous protein in extracellular spaces of mammals. It is an inhibitor of endopeptidases, can be modified by aliphatic amines, and combines with a number of hormones/cytokines such as β‐nerve growth factor (NGF) [Koo PH, Stach RW (1989): J Neurosci Res 22:247]. The objective of this study is to compare the NGF‐binding properties of methylamine‐modified human α2M (MA‐α2M) versus normal α2M and their effects on the biological activity of NGF and neurite extension by embryonic chicken dorsal root ganglia. As determined by gel filtration, polyacrylamide gel electrophoresis, and equilibrium binding studies, these two forms of α2M are similar in their binding affinities, with MA‐α2M binding about twice as much NGF as normal α2M. Both normal α2M and MA α2M combine noncovalently with NGF, and prior modification of α2M is unnecessary for the binding to occur. In contrast to normal α2M, MA‐α2M potently inhibits the biological activity of NGF and exerts a dose‐dependent inhibition on the NGF‐stimulated neurite outgrowth by embryonic chicken dorsal root ganglia in culture. The inhibitory effect of MA‐α2M can be overcome by higher NGF concentrations, but is irreversible at lower NGF concentrations. Trypsin‐modified α2M combines covalently and noncovalently with more NGF than normal α2M but has very little neurite inhibitory activity. The mechanism of inhibition by MA‐α2M is discussed.
Function and evolution in the NGF family and its receptors
Authors: Ebendal T.
Published: May 2005

The gene family of neurotrophins includes nerve growth factor (NGF), brain‐derived neurotrophic factor (BDNF), neurotrophin‐3 (NT‐3), and neurotrophin‐4 (NT‐4). Recently, neurotrophin‐5 (NT‐5), a possible mammalian homologue to NT‐4 described in the frog Xenopus, has been cloned in man and rat. The neurotrophins stimulate survival and differentiation of a range of target neurons by binding to cell surface receptors. The structure of NGF has recently been clarified from crystallographic data. The similarities between the different neurotrophins are substantial with the variable regions, giving specificity to each of the family members, being localized to some exposed loop regions. Low‐affinity binding (Kd of 10−9 M) of all tested neurotrophins is mediated via a 75 K glycoprotein (LNGFR) that has been cloned and characterized. A 140 K tyrosine protein kinase encoded by the proto‐oncogene trk has been found to bind NGF with high affinity (Kd of 10−11 M) and to evoke the cellular neurotrophic responses. In addition, a protein encoded by the trk‐related gene trkB has been shown to bind BDNF. Recently, a third member of the trk family, trkC, has been cloned and demonstrated to function as a high‐affinity receptor for NT‐3. The expression of trk and LNGFR mRNA are co‐localized in the rat brain to the medial septal nucleus and the nucleus of Broca's diagonal band containing the NGF‐responsive magnocellular cholinergic neurons projecting to hippocampus and cerebral cortex. In sharp contrast, the pattern of expression of trkB is widely spread in many areas of the cortex as well as lateral septum. The trkB protein might serve general functions in large areas of the cortex. Site‐directed mutagenesis and expression of recombinant chimaeric neurotrophin proteins have made it possible to localize a likely region for the interaction between NGF and the LNGFR. This region could be altered, resulting in the total loss of LNGFR binding by the mutant NGF protein without affecting the binding to the trk receptor which was sufficient for the full biological activity. Cladistic analysis of likely phylogenies within the neurotrophins shows BDNF and NT‐4 to be most closely related whereas NGF may be the sister group to NT‐3, BDNF, and NT‐4. Neurotrophins offer obvious clinical possibilities for treatment of neurodegenerative diseases. © 1992 Wiley‐Liss, Inc.