Correlation of gas chromatographic properties of chlorobenzenes and polychlorinated biphenyls with the occurrence of reductive dechlorination by untamed microorganisms

To understand the dechlorination ability of chlorobenzenes (CBs) and polychlorinated biphenyls (PCBs) by untamed microorganisms under anaerobic condition and to correlate gas chromatographic properties with the occurrence of reductive dechlorination, introduction of CBs and PCBs in the culture medium inoculated with microorganisms from sludge and sediment, respectively, were performed. Three kinds of culture media preparing from sludge, river water and a synthetic medium were used in the experiments. HCB was degraded to 1,3,5-trichlorobenzene (1,3,5-TCB) and 1,3-dichlorobenzene (1,3-DCB) in both sludge medium and synthetic medium with inoculated microorganisms. Three PCB congeners including 2,3,4-, 3,4,5- and 2,3,4,5-CBp (chlorinated biphenyl) were not found to be dechlorinated in the river water medium with inoculation culture but to be dechlorinated in the synthetic medium. MNDO methodology was used to compute theoretical dechlorination reaction heats and GC-ECD techniques were used to estimate chromatographic data of CB and PCB congeners. Both CB and PCB congeners showed that dechlorination by untamed microorganisms under anaerobic mixed cultures were more likely to occur when larger amounts of energy were released and greater deltaln RRT value between the parent congener and the daughter product was observed. Deltaln RRT provided a more precise information on the singularity of PCBs ortho-dechlorination in an aspect of thermodynamic favorable rule.

Down-regulation of Fas-L in glioma cells by ribozyme reduces cell apoptosis, tumour-infiltrating cells, and liver damage but accelerates tumour formation in nude mice

Fas-L (CD95L, APO-1L) expresses in a variety of tumours and has been proposed to play a role in tumour formation and metastasis. The contribution of Fas-L to tumour growth, however, is not conclusive especially in systems using cells with over-expressed Fas-L. In this study we down-regulated the expression o Fas-L in human glioma cells by a hammerhead ribozyme (Fas-L(ribozyme)) targeting against Fas-L mRNA. Fas-L(ribozyme)-carrying cells exhibited slightly enhanced growth rate and less degree of spontaneous apoptosis in vitro as compared with vector controls. In nude mice, Fas-L(ribozyme)-carrying cells grew faster with lesser apoptosis, formed bigger tumour with significantly fewer infiltrating cells in the tumour area, and triggered relatively milder tumour-associated liver damage than vector controls did. Thus, down-regulation of Fas-L not only improved viability of glioma cells but also reduces local immune responses that may consequently affect tumour formation. Taken together, our findings imply that endogenous expression of Fas-L in malignant cells is not always growth promoting.

Design, high-level expression, purification and characterization of soluble fragments of the hepatitis C virus NS3 RNA helicase suitable for NMR-based drug discovery methods and mechanistic studies

RNA helicases represent a family of enzymes that unwind double-stranded (ds) RNA in a nucleoside triphosphate (NTP)-dependent fashion and which are required in all aspects of cellular RNA metabolism and processing. The hepatitis C virus (HCV) non-structural 3 (NS3) protein possesses a serine protease activity in the N-terminal one-third, whereas RNA-stimulated NTPase and helicase activities reside in the C-terminal portion of the 631 amino acid residue bifunctional enzyme. The HCV NS3 RNA helicase is of key importance in the life cycle of HCV, which makes it a target for the development of therapeutics. However, neither the precise mechanism nor the substrate structure has been defined for this enzyme. For nuclear magnetic resonance (NMR)-based drug discovery methods and for mechanistic studies we engineered, prepared and characterized various truncated constructs of the 451-residue HCV NS3 RNA helicase. Our goal was to produce smaller fragments of the enzyme, which would be amenable to solution NMR techniques while retaining their native NTP and/or nucleic acid binding sites. Solution conditions were optimized to obtain high-quality heteronuclear NMR spectra of nitrogen-15 isotope-labeled constructs, which are typical of well-folded monomeric proteins. Moreover, NMR binding studies and functional data directly support the correct folding of these fragments.

The kinetics and thermodynamics of surfactants in solvent sublation

Solvent sublation has been performed on very dilute solutions of one cationic surfactant, hexadecylpyridinium chloride (HPC), and one anionic surfactant, dodecylbenzenesulfonic acid (LBS). Some thermodynamic values were obtained, e.g. molecular areas, A0, which are 50.0 and 47.7 A2/molecule, respectively, for HPC and LBS, and free adsorption energies, delta G(o)ads, which are -33.17 and -43.58 kJ mol(-1), respectively, for HPC and LBS. The kinetics were determined for a range of temperatures and gas flow-rates. Although the processes of solvent sublation of the two surfactants obey first-order kinetics, the respective adsorption mechanisms of HPC and LBS in the solvent sublation process were different. The pH and the presence of KCl and ethanol had no effect on the solvent sublation of LBS. The apparent active energy was calculated as 8.11 kJ mol(-1).

Monoclonal antibodies against human ribosomal P proteins penetrate into living cells and cause apoptosis of Jurkat T cells in culture

OBJECTIVE

This study was designed to determine the role of autoantibodies to the ribosomal P protein (anti-P Abs) in the pathogenesis of systemic lupus erythematosus (SLE) using monoclonal anti-P antibodies (anti-P mAbs).

METHODS

Anti-P mAbs were prepared by a standard hybridoma procedure using recombinant human P1 and P2 proteins as immunogens. We studied the reactivities of these mAbs to P proteins, their binding and penetration capabilities in different cell lines and their apoptotic effects on Jurkat T cells.

RESULTS

In addition to recognizing human P0, P1 and P2 proteins, the anti-P mAb 9B6-4 bound to 20-40% and penetrated 50-90% of astrocytes, Jurkat T cells and lung cancer cells via the P0 surface protein. Treatment with the mAb 9B6-4 also caused increases in the percentages of Jurkat T cells in the sub-G1 phase of the cell cycle (14.8%) and undergoing apoptosis (21.3%).

CONCLUSION

Anti-P autoantibodies may play a role in the pathogenesis of lymphopenia or lymphocyte dysfunction in SLE.

Environmental dissipation of fungicide triphenyltin acetate and its potential as a groundwater contaminant

The effects of various factors on fungicide triphenyltin acetate dissipation in selected soil types were studied; temperature is clearly the most important factor of these. Residues of this fungicide in Fangtzupo clay loam and Lanyang loam incubated at 30 degrees C for 32 days (water content 100, 70, or 40% of field capacity) were 25% of the original amounts. In soil samples incubated at 10, 30, or 40 degrees C with 100% field capacity water content, residues were 80, 26, and 5.5% for Fangtzupo soil, respectively, and 83, 26, and 7.0% for Lanyang soil, respectively. No significant difference in dissipation rate was found between sterilized and unsterilized soil, suggesting that microbial degradation is not an important factor in this process. Rapid degradation rates were observed-half-lives of 8.3 to 19.4 days in Fangtzupo clay loam and 8.0 to 16.3 days in Lanyang loam at temperatures ranging from 30 to 40 degrees C (soil water content of 100, 70, and 40% of field capacity). Significant increases in half-life (approximately 150 days) occurred at lower temperatures (10 degrees C) in both soil types. The potential of triphenyltin acetate to contaminate groundwater was tested using the behavior assessment and groundwater pollution-potential models. Results indicate that the leaching rate of the fungicide is very slow (1.0 cm day(-1)) under normal conditions.

Application of microbial enumeration technique to evaluate the occurrence of natural bioremediation

Natural bioremediation is believed to be the major processes that account for both containment of the petroleum-hydrocarbon plume and reduction of the contaminant concentrations. In this study, the feasibility of applying the microbial enumeration technique was assessed for natural biodegradation evaluation at three selected gasoline spill sites. At each site, two monitor wells were installed along the groundwater flow, and one multilevel sampler (MLS) was installed to delineate the vertical distribution of the contaminant plume. Two continuous soil cores were collected at each site to evaluate the horizontal distribution of the microbial activity. Soil samples were used for microbial enumeration, grain-size distribution analysis, and sediment extraction. In situ tracer study was performed using 1,2,4-trimethylbenzene (1,2,4-TMB) as the tracer to study the efficiency of contaminant biodegradation. Investigation results demonstrate the agreement between microbial enumeration and other evaluation techniques for natural bioremediation (e.g., geochemical indicator analysis, tracer study). Results suggest that the microbial enumeration is useful in assessing the occurrence, efficiency, and status of the bioremediation. Because this technique provides insight into factors controlling contaminant biodegradation, it could be performed as the supplemental method for natural bioremediation evaluation at petroleum-hydrocarbon spill sites.

[Experimental study on the hemostatic properties of collagen sponge]

OBJECTIVE

To validate the hemostatic properties of collagen sponge made in China.

METHODS

The experimental model of superficial cut of liver was established in 20 Sprague-Dawley adult rats, which were divided into two groups randomly. Collagen sponge or gelatin sponge was used to cover the cut respectively. Hemostatic result was observed. Afterwards, standard liver trauma model by resection left front liver lobe was made, wound was treated with collagen sponge or gelatin sponge respectively. Hemostatic result was observed. Concurrent hemostatic time and bleeding amount were noted. At 7, 14 and 20 days after operation, intra-abdominal adhension, infection and healing state of liver were observed by exploratory laparotomy. The histological changes of regenerate liver tissue were observed by microscopy.

RESULTS

Collagen sponge adhered to wound well. Concurrent hemostatic time and bleeding amount in collagen sponge group were superior to those of gelatin sponge (P < 0.05). The histological examination showed that collagen sponge was absorbed and degraded rapidly, regenerative hepatocytes could be induced.

CONCLUSION

Collagen sponge has fine hemostatic properties and can induce regeneration of hepatocytes effectively. It is worth popularizing for its convenience in clinical application and its properties of rapid degradation and absorption.

Comparisons of PCBs dechlorination occurrences in various contaminated sediments

A comparison was made of reductive dechlorination occurrences of polychlorinated biphenyls (PCBs) by microorganisms collected from contaminated sediments including Er-Jen River (Tainan, Taiwan), Hudson River (Ft. Edward, NY), Silver Lake (Pittsfield, MA) and Puget Sound (Washington State). Comparisons was made in terms of chromatographic data (referring to the biological activity, including microbial availability) and thermodynamic data (demonstrating the selectivity of anaerobic microorganisms in the dechlorination of chlorinated compounds). Chromatographic data was established in terms of difference in relative retention time (delta ln RRT) and thermodynamic data was estimated as heat of reaction (delta H(r)0). Both were calculated and correlated to occurrences of dechlorination reactions. Observed dechlorination reactions for individually introducing PCB congener had delta ln RRT levels measured as >0.47 (Er-Jen River), >0.29 (Hudson River), >0.36 (Silver Lake) and >0.45 (Puget Sound, for Aroclor 1254 dechlorination). Critical of delta H(r)0 and delta ln RRT values showed that Hudson River and Silver Lake microorganisms were capable of dechlorinating PCBs through reactions with larger H(r)0 value (lower levels of released energy) and smaller delta ln RRT value compared with those found in Er-Jen River and Puget Sound sediments. Differences in the critical delta ln RRT values of these sediments may be due to differences in their levels of PCB contamination.

Leo Eloesser: an American cardiothoracic surgeon in China

We present a brief historical vignette about one of the pioneer cardiothoracic surgeons, Leo Eloesser, from our personal recollections and descriptions of part of his long life that was spent in China. Although this article deals mainly with his time in China during his close association with the senior author, Dr Eloesser is certainly one of the most extraordinary surgeons of the 20th century.

Preclinical evaluation of locoregional delivery of radiolabeled iododeoxyuridine and thymidylate synthase inhibitor in a hepatoma model

We report improved incorporation of the radiolabeled-thymidine analog [125I/131I]5-iodo-2'-deoxyuridine ([125I/131I]IdUrd) into DNA by the addition of Thymitaq, a thymidylate synthase inhibitor, as a strategy of molecular radiotherapy for hepatoma treatment.

METHODS

The synergistic effect of combination [125I]IdUrd and Thymitaq in clonogenic survival and DNA incorporation was shown on the human hepatoma cell line Hep3B. Radiobiodistribution of intrahepatic arterially injected [125I]IdUrd and Thymitaq was studied in a rat N1S1 hepatoma model. In vivo therapeutic effects of locoregional delivery of both drugs were evaluated in mouse subcutaneous hepatoma and ascitic hepatoma models.

RESULTS

In a clonogenic assay, Thymitaq showed a synergistic effect with [125I]IdUrd but not cold IdUrd. Thymitaq had a dose-dependent modulation effect on DNA-[125I]IdUrd incorporation. The biodistribution study indicated a slower clearance rate of [125I]IdUdR in the hepatoma as well as an initially higher uptake of [125I]IdUrd into DNA when the [125I]IdUrd was combined with Thymitaq. In vivo studies showed a superior therapeutic effect of combination Thymitaq and [125I]IdUrd in both subcutaneous and ascites tumor models, but the combination of [131I]IdUrd and [125I]IdUrd may be more effective than Auger electron emitters alone for the treatment of subcutaneous tumor.

CONCLUSION

The strategy of locoregional delivery of [125I/131I]IdUrd to a tumor site through an intrahepatic arterial, intratumoral, or intraperitoneal route in combination with Thymitaq is promising and may also have a favorable therapeutic index in vivo.

[Methodological studies on quantitative determination of beta-eudesmol in Atractylodes lancea (thunb.) DC]

OBJECTIVE

To establish methodologically a method for quantitative determination of beta-eudesmol in Atractylodes lancea.

METHOD

GC, column: 3 mm x 2 m; stationary phase; 15% QF-1; support: Chromosorb WAW(60-80 mesh); detector: hydrogen flame ionization detector; injection chamber temperature: 210 degrees C; column temperature: 174 degrees C; carrier gas: N2:50 ml.min-1, air: 49 kPa, H2:58.8 kPa; sensibility range: 10(2) x 64; chart speed: 2.5 mm.min-1.

RESULT

Average recovery ratio is 100.7% (n = 5).

CONCLUSION

This method can be used to control the quality of A. lancea.

The HIV glycoproteins gp41 and gp120 cause rapid excitation in rat cortical slices

Inflammation and associated excitotoxicity may play important roles in various neurodegenerative diseases including AIDS dementia. Here we show that exposure of rat parietal cortical slices to the HIV glycoproteins gp120 and gp41 triggered very rapid releases of the neurotransmitters glutamate and [(3)H]noradrenaline (NA), and of the neuromodulator adenosine. Gp41 was more effective than gp120 at releasing glutamate and [(3)H]NA, while both glycoproteins were equi-effective at releasing adenosine. The responses to gp120 and gp41 declined rapidly to basal levels following their removal. It seems possible that rapid, inappropriate excitation may occur in the immediate vicinity of HIV infections in the brain, possibly producing some of the transient neurological and psychiatric symptoms associated with AIDS dementia.

Identification of the major positional isomer of pegylated interferon alpha-2b

Interferons display a wide range of antiviral, antiproliferative, and immunomodulatory activities on a variety of cell types and have been used to treat many diseases including hairy-cell leukemia and hepatitis B and C and have also been applied to other therapeutic areas. To improve the pharmacological properties of interferon (IFN) alpha-2b, a long-acting pegylated form (PEG-IFN) has been developed [PEG, monomethoxy poly(ethylene glycol) with average molecular mass of 12 000 Da]. PEG-IFN is a mixture of pegylated proteins with differing sites of PEG attachment. To identify the major positional isomer in the pegylated material [PEG-IFN(His-34)], NMR studies were conducted on a subtilisin-digested N-acetylated peptide of the major positional isomer [PEG-IFN(His-34)dig], synthetic peptide analogues containing His-34, as well as unmodified IFN and PEG-IFN(His-34). Our studies reveal a novel interferon-polymer attachment site as a histidine-linked interferon conjugate. We show that the major component of PEG-IFN is pegylated in the imidazole side chain of histidine-34. Chemical shift data suggest that pegylation occurs mainly at the N(delta)(1) position in the imidazole side chain of this residue. This positional isomer, PEG-IFN(His-34), comprises approximately 47% of the total pegylated species when PEG-IFN is synthesized under the current experimental conditions at pH 6.5 with an electrophilic derivative of PEG, succinimidyl carbonate PEG. The reversibility of the histidine modification was examined. The PEG-imidazole adduct in the intact protein, PEG-IFN(His-34), is labile but much more stable than in the peptide, PEG-IFN(His-34)dig. Apparently, the tertiary structure of the intact protein protects the His(34)-imidazole ring from depegylation.

Molecular characterization of a urea transporter in the gill of the gulf toadfish (Opsanus beta)

Urea excretion by the gulf toadfish (Opsanus beta) has been shown in previous studies to be a highly pulsatile facilitated transport, with excretion probably occurring at the gill. The present study reports the isolation of an 1800 base pair (kb) cDNA from toadfish gill with one open reading frame putatively encoding a 475-residue protein, the toadfish urea transporter (tUT). tUT, the first teleostean urea transporter cloned, has high homology with UTs (facilitated urea transporters) cloned from mammals, an amphibian and a shark, and most closely resembles the UT-A subfamily. When expressed in Xenopus laevis oocytes, tUT increased urea permeability (as measured by [(14)C]urea uptake) five- to sevenfold, and this permeability increase was abolished by phloretin, a common inhibitor of other UTs. Northern analysis using the 1.8 kb clone was performed to determine the tissue distribution and dynamics of tUT mRNA expression. Of six tissues examined (gill, liver, red blood cells, kidney, skin and intestine), only gill showed expression of tUT mRNA, with a predominant band at 1.8 kb and a minor band at 3.5 kb. During several points in the urea pulse cycle of toadfish (0, 4, 6, 12 and 18 h post-pulse), measured by excretion of [(14)C]urea into the water, gill mRNA samples were obtained. Expression of tUT mRNA was found to be largely invariant relative to expression of beta-actin mRNA over the pulse cycle. These results further confirm the gill localization of urea transport in the toadfish and suggest that tUT regulation (and the regulation of pulsatile urea excretion) is probably not at the level of mRNA control. The results are discussed in the context of the mechanisms of vasopressin-regulated UT-A in mammalian kidney and morphological data for the toadfish gill.

Transient apoptosis elicited by insulin in serum-starved glioma cells involves Fas/Fas-L and Bcl-2

The expression of fas gene in glioma cells varies with growth stage. When insulin-elicited transient apoptosis of glioma cells was in progress, the expression of fas gene increased at both transcriptional and translational levels. In contrast, the expression of fas-L gene in glioma cells remained constant. Apoptosis occurred in the cells having high level of surface Fas protein. When the expression of Fas-L in U-373MG cells was suppressed by ribozyme, the insulin-elicited transient apoptosis vanished. Overexpression of Bcl-2 in U-373MG cells did not alter significantly the cell cycle progression and the expression of fas gene. However, these cells were resistant to insulin-trigged death. Therefore, insulin-elicited apoptosis involved Fas-related death signal, and which could be prevented by the protective effect of Bcl-2.

Ras signaling is involved in the expression of Fas-L in glioma

Fas-L expresses on a variety of tumors and is suspected to modify the dialog between tumor and the immune system. However, the cellular abnormality in tumor cells leading to an aberrant expression of Fas-L is unclear. In this study, we demonstrate the involvement of Ras signaling in the Fas-L expression in several ways. First, the activated Ha-rasval12 gene enhanced the Fas-L expression of primary human glial cells. Second, blocking the Ras signal pathway in glioma cells by lovastatin or the Ha-rasAsn17 dominant-negative mutant gene resulted in reduced Fas-L expression. Transfection of the Ha-rasAsn17 into glioma cells also inhibited the activation of NFKB, which is a downstream component of Ras signaling. Accordingly, the membrane-permeable NFKB competitor suppressed the Fas-L expression. Furthermore, the Fas-L expression coincided with the Ras activity in the murine 212 cells, in which the Ras activity could be induced by isopropyl 3-D-thiogalactoside. In summary, these results suggest that the enhanced Ras signaling with consequential NFKB activation, which is a frequent defect found in tumors, could mediate the Fas-L expression of tumors.

An efficient method for in vitro fertilization in rabbits

This experiment was carried out to study a simple and efficient method for in vitro production of rabbit embryos. Newly ejaculated rabbit spermatozoa were used to fertilize superovulated oocytes after capacitation in vitro with four different media: (A) isotonic defined medium (DM)+heparin, (B) DM only,(C) DM+ high ionic strength defined medium (HIS), and (D) DM supplemented with 10mM NaHCO3 (mDM) +HIS supplemented with 10mM NaHCO3 (mHIS). The presumptive zygotes were cultured in M199 supplemented with 10% FCS, 1.25mM Na Pyruvate and 0.1mM EDTA (mM199). The cleavage rates after 24h of incubation were 29.3%, 32.1%, 64.9%, and 91.6% respectively, and the rates of blastocyst formation after 72h were 0, 27.3%, 58.4% and 85.2%, respectively. The results in the (D) treatment were significantly better than the other three treatments (p<0.01). Developmental potential of in vivo and in vitro derived zygotes was also compared using the mM199. The percentages of blastocyst and hatching blastocyst in the two groups were 92.5% and 87.2% after 84h, and 84.9% and 83.7% after 108h, respectively, and the two groups were not significantly different (p>0.05). The developmental progress of the two groups was nearly synchronous towards the end of culture. When IVF embryos from 2- to 4-cell stage were transferred into recipients, the pregnancy rate did not differ from in vivo fertilization, but the rate of live young from IVF was significantly lower than from in vivo. The results of this experiment showed that ejaculated rabbit sperm could be capacitated efficiently after treatment of mDM and mHIS, and rabbit IVF embryos achieved great development in mM199 in vitro.

Induction of carbamoyl phosphate synthetase III and glutamine synthetase mRNA during confinement stress in gulf toadfish (Opsanus beta)

Gulf toadfish (Opsanus β) rapidly switch to excretion of urea as their main nitrogenous waste product under several laboratory conditions, including confinement to small volumes of water. Prior evidence suggested that the activities of two key enzymes of urea synthesis exhibited potentially different modes of upregulation during this switch, with carbamoyl phosphate synthethase III (CPSase III) activated allosterically by N-acetylglutamate, and glutamine synthetase (GSase) activated by increases in the concentration of protein. The present study was undertaken to examine additional aspects of the regulation of these enzymes. The sequence for O. beta CPSase III cDNA was obtained, and it was found to be similar to that of other piscine CPSases. The sequence also allowed us to develop riboprobes for CPSase III mRNA analysis using ribonuclease protection assays (RPAs). CPSase III mRNA was expressed in liver, muscle, kidney and intestine, in agreement with prior enzymatic measurements. Levels of CPSase III mRNA increased five- to tenfold (relative to beta-actin mRNA) in liver (but not muscle) following 48 h of confinement stress. Measured by western analysis using an antibody to chicken GSase, confined O. beta GSase protein concentrations increased eightfold over control levels, in agreement with prior and present measurements of increases in GSase activity. Furthermore, RPAs of GSase mRNA levels demonstrated an increase of fivefold during confinement.

Potential of the insecticides acephate and methamidophos to contaminate groundwater

The possible contamination of groundwater by the insecticides acephate and methamidophos was assessed using the behavior assessment model (BAM) and the groundwater pollution-potential model (GWP). The dissipation coefficients of the two insecticides in two soils (Annei silt loam and Pingchen silt clay loam) at different moisture contents (50 and 100% field capacity) and soil temperatures (20 and 30 degrees C) were studied by determining the degradation and adsorption of each insecticide in the soil. The movement of acephate and methamidophos was studied by leaching each insecticide in a soil column in the laboratory. The absorption coefficient of methamidophos was much higher than that of acephate in both types of soil. In the leaching test, methamidophos more easily leached out from the Pingchen soil column than from the Annei soil column. Methamidophos was rapidly degraded, with a half-life of 1.11 to 1.61 days in the Annei soil and 7.50 to 13.20 days in the Pingchen soil at different temperatures and soil water contents. Acephate was found to have a longer half-life than methamidophos in soil; however, the mobility of methamidophos in both soils was slower than that of acephate. The mobility of acephate in soil is somewhat faster than that of methamidophos, and thus acephate may lead to the contamination of groundwater much more easily than methamidophos under normal conditions.

Two-photon optical-beam-induced current imaging of indium gallium nitride blue light-emitting diodes

Epilayers of packaged indium gallium nitride light-emitting diodes (LED's) are characterized by optical-beam-induced current (OBIC) and photoluminescence laser-scanning microscopy through two-photon excitation. Light scattering and absorption in the packaging material and the p-doped top layer of the LED's are greatly reduced as a result of employing a longer excitation wavelength, with energy that is less than the bandgap of the top p layer. Compared with single-photon OBIC, two-photon OBIC imaging not only exhibits superior image quality but also reveals more clearly the characteristics of the epilayers that are being focused on.

The bacterial endotoxin lipopolysaccharide causes rapid inappropriate excitation in rat cortex

There is mounting evidence that inflammation and associated excitotoxicity may play important roles in various neurodegenerative disorders, such as bacterial infections, Alzheimer's disease, AIDS dementia, and multiple sclerosis. The immunogen E. coli lipopolysaccharide (LPS, endotoxin) has been widely used to stimulate immune/inflammatory responses both systemically and in the CNS. Here, we show that exposure of parietal cortical slices from adult rats to LPS triggered very rapid (<2.5 min) and sustained releases of the neurotransmitters glutamate and noradrenaline, and of the neuromodulator adenosine. The responses to LPS declined rapidly following removal of the LPS and exhibited no tachyphylaxis to repeated exposures to LPS. The detoxified form of LPS had no effect. LPS-evoked release of [3H]noradrenaline, but not of glutamate or adenosine, appears to be partly due to the released glutamate acting at ionotropic receptors on the noradrenergic axons present in the cortical slices. LPS appears to release glutamate, which then acts at non-NMDA receptors to remove the voltage-sensitive Mg2+ block of NMDA receptors, thus permitting NMDA receptors to be activated and noradrenaline release to proceed. It seems possible that rapid, inappropriate excitation may occur in the immediate vicinity of gram-negative bacterial infections in the brain. If similar inappropriate excitations are also triggered by those immunogens specifically associated with Alzheimer's disease (beta-amyloid), AIDS dementia (gp120 and gp41), or multiple sclerosis (myelin basic protein), they might explain some of the acute, transient neurological and psychiatric symptoms associated with these disorders.

Alpha 1-acid glycoprotein-induced tumor necrosis factor-alpha secretion of human monocytes is enhanced by serum binding proteins and depends on protein tyrosine kinase activation

The acute phase protein, alpha1 acid glycoprotein (AGP), stimulated human mononuclear cells as well as monocytes to secrete tumor necrosis factor-alpha (TNFalpha) which was demonstrated by ELISA, RT-PCR and functional assays. AGP-induced TNFalpha secretion of monocytes was enhanced in the presence of human plasma and inhibited by protein kinase inhibitors, indicating it is serum and tyrosine kinase dependent. The activation of tyrosine kinase in AGP-stimulated monocytes was further confirmed by immunoblotting of tyrosine phosphorylated proteins of monocytes at different time after AGP stimulation. Furthermore, several serum proteins such as C3, sCD14 and IgG were able to bind to AGP and enhanced TNFalpha secretion of human monocytes induced by AGP. Taken together, these results suggest serum proteins binding to AGP enhance its ability to stimulate human monocytes to secrete pro-inflammatory cytokines through a tyrosine kinase dependent pathway.

Interaction of a novel GDP exchange inhibitor with the Ras protein

Mutated, tumorigenic Ras is present in a variety of human tumors. Compounds that inhibit tumorigenic Ras function may be useful in the treatment of Ras-related tumors. The interaction of a novel GDP exchange inhibitor (SCH-54292) with the Ras-GDP protein was studied by NMR spectroscopy. The binding of the inhibitor to the Ras protein was enhanced at low Mg2+ concentrations, which enabled the preparation of a stable complex for NMR study. To understand the enhanced inhibitor binding and the increased GDP dissociation rates of the Ras protein, the conformational changes of the Ras protein at low Mg2+ concentrations was investigated using two-dimensional 1H-15N HSQC experiments. The Ras protein existed in two conformations in slow exchange on the NMR time scale under such conditions. The conformational changes mainly occurred in the GDP binding pocket, in the switch I and the switch II regions, and were reversible. The Ras protein resumed its regular conformation after an excess amount of Mg2+ was added. A model of the inhibitor in complex with the Ras-GDP protein was derived from intra- and intermolecular NOE distance constraints, and revealed that the inhibitor bound to the critical switch II region of the Ras protein.