Comprehensive Kinetics of Hydrolysis of Organotriethoxysilanes by 29Si NMR

The kinetics of several representative hybrid precursors were studied via ²⁹Si NMR: three alkyl precursors, methyltriethoxysilane, ethyltriethoxysilane, and propyltriethoxysilane; as well as two unsaturated radicals, vinyltriethoxysilane and phenyltriethoxysilane. The reaction rate is related to the chemical shift of ²⁹Si in the NMR spectra, which gives information about the electronic density of the Si atoms and the inductive effects of substituents. The concentration of the precursors decreased exponentially with time, and the intermediate products of hydrolysis and the beginning of the condensation reactions showed curves characteristic of sequential reactions, with a similar distribution of the species as a function of the fractional conversion. For all of the precursors, condensation started when the most hydrolyzed species reached a maximum concentration of 0.30 M, when the precursor had run out. A prediction following the developed mathematical model fits the experimental results in line with a common pathway described by eight parameters.

Comprehensive analysis of pig feces metabolome by chromatographic techniques coupled to mass spectrometry in high resolution mode: Influence of sample preparation on the identification coverage

Pig feces is an interesting biological sample to be implemented in metabolomics experiments by virtue of the information that can be deduced from the interaction between host and microbiome. However, pig fecal samples have received scant attention, especially in untargeted metabolomic studies. In this research, an analytical strategy was planned to maximize the identification coverage of metabolites found in pig fecal samples. For this purpose, two complementary platforms such as LC-QTOF MS/MS and GC-TOF/MS were used. Concerning sample preparation six extractant solvents with different polarity grade were tested to evaluate the extraction performance and, in the particular case of GC-MS, two derivatization protocols were compared. A total number of 303 compounds by combination of all the extractants and analytical platforms were tentatively identified. The main identified families were amino acids, fatty acids and derivatives, carbohydrates and carboxylic acids. For GC-TOF/MS analysis, the recommended extractant is methanol, while methoxymation was required in the derivatization protocol since this step allows detecting the α-keto acids, which are direct markers of the microbiome status. Concerning LC-QTOF MS/MS analysis, a dual extraction approach with methanol (MeOH) or MeOH/water and ethyl acetate is proposed to enhance the detection of polar and non-polar metabolites.

Dysfunction of the PI3K-Akt-GSK-3 pathway is a common feature in cell culture and in vivo models of prion disease

AIMS

Transmissible spongiform encephalopathies, also called prion diseases, are characterized by the cerebral accumulation of misfolded prion protein (PrP(SC) ) and subsequent neurodegeneration. However, despite considerable research effort, the molecular mechanisms underlying prion-induced neurodegeneration are poorly understood. Here, we explore the hypothesis that prions induce dysfunction of the PI3K/Akt/GSK-3 signalling pathway.

METHODS

We employed two parallel approaches. Using cell cultures derived from mouse primary neurones and from a human neuronal cell line, we identified common elements that were modified by the neurotoxic fragment of PrP(106-126) . These studies were then complemented by comparative analyses in a mouse model of prion infection.

RESULTS

The presence of a polymerized fragment of the prion protein (PrP(106-126) ) or of a prion strain altered PI3K-mediated signalling, as evidenced by Akt inhibition and GSK-3 activation. PI3K activation by the addition of insulin or the expression of a constitutively active Akt mutant restored normal levels of Akt and GSK-3 activity. These changes were correlated with a reduction in caspase activity and an increase in neuronal survival. Moreover, we found that activation of caspase 3, Erk and GSK-3 are common features of PrP(106-126) -mediated neurotoxicity in cellular systems and prion infection in the mouse cerebellum, while activation of caspase 12 and JNK was observed in cellular models.

CONCLUSIONS

Our findings in cell culture and in vivo models of prion disease demonstrate marked alterations to the PI3K/Akt/GSK-3 pathway and suggest that two additional pathways contribute to PrP-induced neurotoxicity as responsible of JNK and caspase 12 activation.

Hsp90 activity is necessary to acquire a proper neuronal polarization

Chaperones are critical for the folding and regulation of a wide array of cellular proteins. Heat Shock Proteins (Hsps) are the most representative group of chaperones. Hsp90 represents up to 1-2% of soluble protein. Although the Hsp90 role is being studied in neurodegenerative diseases, its role in neuronal differentiation remains mostly unknown. Since neuronal polarity mechanisms depend on local stability and degradation, we asked whether Hsp90 could be a regulator of axonal polarity and growth. Thus, we studied the role of Hsp90 activity in a well established model of cultured hippocampal neurons using an Hsp90 specific inhibitor, 17-AAG. Our present data shows that Hsp90 inhibition at different developmental stages disturbs neuronal polarity formation or axonal elongation. Hsp90 inhibition during the first 3h in culture promotes multiple axon morphology, while this inhibition after 3h slows down axonal elongation. Hsp90 inhibition was accompanied by decreased Akt and GSK3 expression, as well as, a reduced Akt activity. In parallel, we detected an alteration of kinesin-1 subcellular distribution. Moreover, these effects were seconded by changes in Hsp70/Hsc70 subcellular localization that seem to compensate the lack of Hsp90 activity. In conclusion, our data strongly suggests that Hsp90 activity is necessary to control the expression, activity or location of specific kinases and motor proteins during the axon specification and axon elongation processes. Even more, our data demonstrate the existence of a "time-window" for axon specification in this model of cultured neurons after which the inhibition of Hsp90 only affects axonal elongation mechanisms.

WIP is a negative regulator of neuronal maturation and synaptic activity

Wiskott-Aldrich syndrome protein (WASP) -interacting protein (WIP) is an actin-binding protein involved in the regulation of actin polymerization in cells, such as fibroblasts and lymphocytes. Despite its recognized function in non-neuronal cells, the role of WIP in the central nervous system has not been examined previously. We used WIP-deficient mice to examine WIP function both in vivo and in vitro. We report here that WIP(-)(/-) hippocampal neurons exhibit enlargement of somas as well as overgrowth of neuritic and dendritic branches that are more evident in early developmental stages. Dendritic arborization and synaptogenesis, which includes generation of postsynaptic dendritic spines, are actin-dependent processes that occur in parallel at later stages. WIP deficiency also increases the amplitude and frequency of miniature excitatory postsynaptic currents, suggesting that WIP(-)(/-) neurons have more mature synapses than wild-type neurons. These findings reveal WIP as a previously unreported regulator of neuronal maturation and synaptic activity.

Pharmacological inhibition of GSK-3 is not strictly correlated with a decrease in tyrosine phosphorylation of residues 216/279

Recent evidence suggests that intramolecular autophosphorylation is responsible for the tyrosine phosphorylation (pY) of residues 279 or 216 of glycogen synthase kinase-3 (GSK-3alpha or beta), an event that appears to play an important role in regulating this kinase. This provocative hypothesis was based on the capacity of certain nonselective GSK-3 inhibitors to alter both the activity of GSK-3 and its pY. Inhibitors of GSK-3 are not always capable of preventing this tyrosine phosphorylation, which may require an extended period of time. For example, although lithium chloride inhibits GSK-3 activity, this inhibition does not alter its pY content. Furthermore, even when GSK-3 activity is impaired, GSK-3 pY can still be modified by physiological or pharmacological agents. Taken together, these data indicate that GSK-3 kinase activity is not necessarily correlated with the extent of GSK-3 pY. We hypothesized that some as-yet-unidentified tyrosine kinases and phosphatases may also regulate this kinase.

Retention of cobalt on a humin derived from brown coal

In this work, the retention of cobalt on a humin (HU) derived from a brown coal is studied. Through a systematic and coordinated investigation of the behavior of the metal ions in solution (speciation diagrams as a function of pH) and their adsorption and precipitation processes with reactive functional groups of the solid (sorption isotherms), the interactions of different Co(II) species with HU are probed. To further confirm the nature of these interactions, the complementary spectroscopic techniques of FTIR, Raman microspectroscopy, UV-visible absorption and XRD are employed. Molecular modeling techniques are used to gain information about the stability of different Co(II) species as a function of pH, as well as the stability of Co(II) species complexed with benzoic acid, a common surface component of humic substances. It is found that the selectivity that humin has for different Co(II) species, as well as the amount of Co(II) that it can retain, are both highly dependent on pH. Through Raman microspectroscopy measurements, the presence and location of Co(OH)(2) precipitates on the surface of HU is confirmed.

Theoretical study on fulvic acid structure, conformation and aggregation. A molecular modelling approach

The ubiquitous presence of humic substances (HS), combined with their ability to provide multiple sites for chemical reaction, makes them relevant to numerous biogeochemical processes such as mineral weathering, nutrient bioavailability, and contaminant transport. The reactivity of HS depends on their functional group chemistry and microstructure, which are in turn influenced by the composition of the surrounding media. In order to help towards an understanding of structure conformations and aggregation process of HS in soils and waters and to get a better knowledge of these kinds of materials, a fulvic acid (FA) has been modelled as a function of its ionic state under different conditions. Our proposed theoretical model based on the Temple-Northeastern-Birmingham (TNB) monomer fits well with experimental observations on the solubility (dipolar moment) and electronic and vibrational spectra of FAs. The presence of water molecules has a great stabilization effect on the electrostatic energy; this effect is greater as ionized rate increases. In vacuum, the non-ionized aggregated species are more stable than monomers because of the increase in their interaction due to H-bonding and non-bonding forces. When the molecules are ionized, no aggregation process takes place. In solution, the FA concentration is a critical factor for the aggregation. The system containing two FA molecules probably did not form aggregates because its equivalent concentration was too low. When the concentration was increased, the system gave rise to the formation of aggregates. The ionic state is another critical factor in the aggregation process. The ionized FA has a higher electric negative charge, which increases the energetic barriers and inhibits the approximation of FA caused by the Brownian movement.

Effect of pH on the aggregation of a gray humic acid in colloidal and solid states

Gray humic acids have a marked colloidal character, a large number of surface functional groups, and are subject to aggregation phenomena. They are able to complex soluble pollutants, and initiate flocculation processes as a function of environmental conditions. The aim of this work is to study the aggregation of a gray humic acid, which is stable in colloidal dispersion, by means of photon correlation spectroscopy, and molecular modeling. The effect of this aggregation in the solid state is also studied by means of N2 (to 77 K) and CO2 (to 273 K) adsorption isotherms, as well as FT-IR absorption. The variation of the colloid's zeta potential and size, with pH, reflects the ionization of the carboxylic and phenolic acidic groups, and a linear dependence of size on zeta potential. The decrease in the size of the colloids seems to be more affected by the ionization of the phenolic acid groups, than by that of the carboxylic acid groups, which is likely because in the case of the ionized carboxylic groups the humic colloids are still capable of generating H-bonds. In the solid state, aggregation effects are illustrated by a decrease in surface area, and a disappearance of certain micropores, with increasing pH. These features are likely due to an inhibition of aggregation in the colloidal state as a consequence of the increase in charge that results from ionization of the acidic groups, and also to an increased hindrance to H-bond formation, due to the loss of protons during the above-mentioned ionization process.

Analysis of Swine β1Integrin (CD29) Epitopes Through Monoclonal Antibodies Developed Using Two Immunization Strategies

This report describes the production and characterization of monoclonal antibodies (MAbs) to swine beta1 integrin subunit (CD29) using two different immunization strategies. MAb GP4B4 was developed from a mouse immunized with porcine peripheral blood mononuclear cells (PBMC), while MAbs GP1A5, GP1A6, and GP4A1 were produced by immunizing mice with a porcine CD29 recombinant protein (rpCD29) developed in our laboratory, which includes the ligand binding site. GP4B4 and UCP1D2 (specific to porcine CD29) immunoprecipitated two bands of approximately 115 and 150 kDa under reducing conditions. The molecule recognized by these two antibodies was studied using flow cytometry and was found in practically all cells studied, displaying a similar reaction pattern. Western blot assays performed with rpCD29 indicated that MAbs GP1A5, GP1A6, and GP4A1 recognized the 30-kDa band for this recombinant protein, confirming their specificity for the beta1, integrin subunit. Immunohistochemical analyses of these MAbs disclosed a morphological pattern associated with smooth muscle, epithelium, and myeloid cells, as expected in MAbs recognizing CD29. This MAb panel could be useful as a general anti-CD29 reagent and would allow further research into this important integrin in swine.

Modeling the adsorption and precipitation processes of Cu(II) on humin

Humins (HU) are the most insoluble fraction of humic substances. Chemically, they can be considered as humic macromolecules bonded to the mineral matter of soil. The HU have a marked colloidal character and they are extremely important in retention of pollutants in soils. The aim of this work is to combine adsorption data with spectroscopic techniques in order to study the adsorption and precipitation processes of Cu(II) on HU. Analysis of sorption isotherms by means of several single-adsorption-process-based models makes it possible to obtain the speciation diagrams of Cu(II) species on HU surfaces. Further, FTIR (which provides information about the changes in the surface groups of the HU) and DRX (which shows the formation of possible crystalline phases on the HU surface) were used to determine the specific interactions of Cu(II) cations with the surface reactive groups of HU. The shape of the isotherms at constant pH varies with pH from L1-type (pH 2-4) to L3-type (pH 5-6) and S-type (pH 8), which indicates a change in the retention mechanism. When pH is 2 the retention of Cu(II), as [Cu(H(2)O)(6)](2+), is the preferred retention mechanism. The retained quantity of Cu(II) as [Cu(OH)(H(2)O)(5)](+) increases with pH. Starting from pH 4 the Cu(II) begins its precipitation, which is the preferred retention mechanism at pH 8. The presence of HU has a great influence on the precipitation process of Cu(II), giving rise to botalackite, which reveals epitaxial growth of crystals.

Cu(II) retention on a humic substance

Humic substances (HS) are macromolecular products derived from a physical, chemical, and microbiological process called "humification." These substances play an important role in the mobility and bioavailability of nutrients and contaminants in the environment. Adsorption isotherms provide a macroscopic view of the retention phenomena. However, complementary techniques are needed in order to study the retention mechanism. The application of the classical models and some modern ones, based on humic substances chemistry, do not accurately describe these adsorption data. The aim of this paper is to model isotherms and combine adsorption data with spectroscopy and microscopy techniques to study the Cu(II) retention on a HS. The adsorption isotherms shape varies significantly with the solution pH from L-type (pH 2-6) to S-type (pH 8). FTIR shows that, when pH is 2 the retention of Cu(II), as [Cu(H(2)O)(6)](2+), is the preferred retention mechanism. The quantity of Cu(II) retained as [Cu(OH)(H(2)O)(6)](+) rises, as pH increases. At pH 4, Cu(II) begins to precipitate, which is the preferred mechanism at pH 8.02. The presence of HS has a great influence on the precipitation process of Cu(II), giving rise to amorphous precipitates. As it is shown by SEM-XRF, Cu(II) distributes heterogeneously on HS surface and accumulates on the humic phases. The presence of different anions (chloride and nitrate) slightly modifies the HS behavior as cation exchanger. When Cl(-) ions are present, part of the Cu(II) form [CuCl(4)](2-), which is stable in solution due to its negative charge; when the anion present is NO(3)(-) the formed complex, [CuNO(3)](+), is retained on the HS.

Molecular cloning, expression pattern and chromosomal mapping of pig CD9 antigen

CD9 is a member of the transmembrane-4 superfamily of surface molecules that seems to have a relevant role in cell migration and adhesion, as well as malignant progression. This work describes the isolation of the cDNA coding for the porcine CD9 molecule. Pig CD9 cDNA was isolated from a smooth muscle cDNA library and contains a 678-bp open reading frame with its predicted polypeptide sequence of 226 amino acids. The deduced amino acid sequence conserves the main characteristics of TM4 proteins, including the presence of four transmembrane domains. Like their homologous molecules from other species, pig CD9 has two extracellular regions of a different size with the minor loop bearing two possible glycosylation sites. The pig CD9 gene was localized to chromosome 5q25 by using a somatic cell hybrid panel. Analysis of CD9 expression in different porcine cells and tissues demonstrated that CD9 mRNA is ubiquitously expressed.

Immunohistochemical analysis of beta3 integrin (CD61): expression in pig tissues and human tumors

CD61 is a membrane glycoprotein that associates with CD41 (alphaIIb) to form the heterodimeric complex gpIIb/IIIa (CD41/CD61), predominantly expressed in platelets and megakariocytes. CD61 or beta3 integrin also associates with alpha v (CD51) to form the vitronectin receptor, which is expressed in many tissues. We have used a monoclonal antibody against the porcine gpIIIa or CD61 (JM2E5) to study the distribution of this molecule in different normal pig tissues. As in humans, CD61 was broadly expressed in all tissues examined. In the kidney, strong expression of CD61 was observed in epithelial cells from renal tubules. In the testis, CD61 expression was detected in the Leydig cells. However, in liver, CD61 was weak or not detected. Many integrins are particularly involved in tumogenicity and in tumor progression mediating cell-cell interaction. Immunofluorescence experiments using cultured human tumor HeLa cells showed nuclear and cytoplasmic staining of mAb JM2E5. Immunohistochemical analysis of human tumor sections from several organs showed a heterogeneus distribution in metastatic cases from colon and breast carcinoma. However, no staining was found in metastasis from melanoma.

Swine platelet antigens: section report

A total of 14 antibodies were found to label resting and/or activated swine platelets. Six recognized CD previously characterized for swine (CD29, CD41/61 and CD46). One had been characterized for human cells (CD47). Two antibodies with CD14 and SLA class I specificity suggested by the donor as well as five blind antibodies were also positive on platelets. One antibody appeared to recognize the swine homologue to human CD47, and four remained unclustered.

Roles of fibroblast growth factor 2 during innervation of the avian inner ear

The importance of individual members of the fibroblast growth factor gene family during innervation of the vertebrate inner ear is not clearly defined. Here we address the role of fibroblast growth factor 2 (FGF-2 or basic FGF) during development of the chicken inner ear. We found that FGF-2 stimulated survival of isolated cochlear and vestibular neurons during distinct phases of inner ear innervation. The potential neurotrophic role of FGF-2 was confirmed by its expression in the corresponding sensory epithelia and the detection of one of its high-affinity receptors in inner ear neurons. Finally, we have analysed the potential of the amplicon system based on defective herpes simplex virus type 1 (HSV-1) vectors to express FGF-2 in cochlear neurons. Overexpression of FGF-2 in cochlear neurons resulted in neuronal differentiation demonstrating the presence of biologically active growth factor. This study underlines the potential of FGF-2 to control innervation and development of sensory epithelia in the avian inner ear. Furthermore, amplicon vectors may provide a useful tool to analyse gene function in isolated neurons of the vertebrate inner ear.

Expression of CD61 (beta3 integrin subunit) on canine cells

A monoclonal antibody (JM2E5) specific for the integrin beta3 chain, or CD61 or GPIIIa subunit, has been employed to determine the expression of the canine homologue CD41/CD61 or CD51/CD61 complex on different canine cells in peripheral blood lymphocytes, monocytes, granulocytes, platelets, erythrocytes, lymph-node cells, spleen cells and breast tumour cells). The canine homologue CD41/CD61 or CD51/61 was present on peripheral blood lymphocytes, monocytes, granulocytes, breast tumour cells and spleen cells as well as on platelets and it was absent from erythrocytes and lymph-node cells. An antigen with components of molecular masses of 25/100/120 kDa (under reducing conditions) was immunoprecipitated from canine peripheral lymphocytes and platelets, but not from granulocytes or monocytes. Expression on canine lymphocytes of the canine homologue of the human beta3 integrin chain was unexpected, based on the expression pattern of this molecule in human tissue.

Isotherms and sequential extraction procedures for evaluating sorption and distribution of heavy metals in soils

Heavy metals are potentially toxic to human life and the environment. Their contaminating effect in soils depends on chemical associations. Hence, determining the chemical form of a metal in soils is important to evaluate its mobility and bioavailability. We utilized a sequential extraction procedure and sorption isotherms (monometal and competitive) to evaluate the mobility and distribution of Cd, Cu, Ni, Pb, and Zn in four soils differing in their physicochemical properties: Calcixerollic Xerochrepts (Cx1 and Cx2), Paralithic Xerorthent (Px) and Lithic Haplumbrept (Lh). Most of the metals retained under point B conditions of sorption isotherms were extracted from the more mobile fractions: exchangeable and carbonates, in contrast with the profiles of the original soils where metals were preferently associated with the residual fraction. In soils having carbonate concentration under 6% (Cx1 and Lh), the exchangeable fraction was predominant, whereas in calcareous soils (Cx2 and Px) metals extracted from carbonates predominated. Partitioning profiles were in accordance with the affinity sequences deduced from the initial slope of isotherms and showed that the soils had a greater number of surface sites and higher affinity for Pb and Cu than for Cd, Ni, or Zn. In general, the simultaneous presence of the cations under study increased the percentages of metals released in the exchangeable fraction. The tendency towards less specific forms was more noticeable in Cx2 and Px soils and for Ni, Zn, and Cd. The affinity of inorganic surfaces was larger for Zn than for Cd or Ni, but the affinity of organic surfaces was larger for Cd or Ni than for Zn.

Molecular cloning and characterization of the pig homologue to human CD29, the integrin beta1 subunit

BACKGROUND

CD29 is the beta1 subunit, a member of the integrin gene superfamily that function as receptor for cell adhesion molecules of the extracellular matrix. Porcine integrin beta1 subunit is involved in rejection of pig-to-human tissue xenografts as target of the natural antibodies present in the human serum. Moreover since CD29, as part of the beta1 integrins very late antigen 4 (VLA-4) and VLA-6, is involved in homing and differentiation of haematopoietic progenitor cells, its characterization in pig is critical to study the interaction of porcine adhesion molecules with human ligands in the induction of donor-specific tolerance toward porcine antigens, a process extremely desirable to prevent rejection of xenogeneic organs.

METHODS

The porcine CD29 cDNA has been isolated from a cDNA library and its structure determined. In addition, reverse transcription-polymerase chain reaction (RT-PCR) was performed to determine the expression of CD29 in different tissues.

RESULTS

The nucleotide sequence of the porcine cDNA includes an open reading frame encoding a polypeptide of 798 amino acids. Expression analysis showed that porcine CD29 is expressed in all lymphoid tissues tested and, in lower amounts, in nonlymphoid tissues. Pig CD29 deduced amino acid sequence displays extensive conservation compared with CD29 sequences from other species and a common structural feature with all the other CD29 molecules analyzed in mammals, including the 12 potential N-glycosilation sites. Punctual changes between human and swine CD29 molecule into the ligand binding domain, and/or into the regulatory domain, suggest potential differences between human and porcine CD29 relative to the human CD29 ligands.

CONCLUSIONS

Cloning of the swine CD29 gene offers a new tool for an alternative protocol of removing xenoreactive antibodies in the recipient. In addition, the determination of the differences between human and swine CD29 will help to understand the adhesion molecule-ligand interactions and their function across the swine-human barrier in xenotransplantation.

Differential effects on the survival of neuronal and non-neuronal cells after infection by herpes simplex virus type 1 mutants

Replication-defective mutants of herpes simplex virus type 1 (HSV-1) are powerful tools to transfer genes into postmitotic neurons and show promise for gene therapy protocols in vivo. To evaluate the efficacy and safety of these vectors for the treatment of deafness we infected dissociated cochlear ganglia with HSV mutants defective in the immediate early genes IE 2 (5dl1.2) or IE 3 (d120). Our results reveal striking differences in the survival of neuronal and non-neuronal cells caused by these mutants. Surprisingly, cochlear neurons infected with 5dl1.2 at various concentrations show a significant increase in survival after 2 days in culture. In contrast, many non-neuronal cells undergo apoptosis reducing cell number to less than 50%. In both neuronal and non-neuronal cell types we also observe a population of cells with important changes in morphology. Analysis of dissociated cochlear ganglia infected with d120 reveals a decrease of neuronal survival, whereas non-neuronal cells were almost unaffected. To further characterize and compare the effects of 5dl1.2 and d120 we transduced central nervous system-derived cell types including cortical neurons and astrocytes. Similarly, as observed for cochlear neurons, infection with 5dl1.2 results in increased survival of cortical neurons, whereas d120 shows cytotoxic effects. Survival of astrocytes is equally reduced by both HSV deletion mutants. We conclude that HSV-1 mutants defective in immediate early genes cause very distinct cytopathic phenotypes depending on the cellular context. Possible reasons for these differences, like various patterns of cellular and viral gene expression, and the implications for the use of HSV-1 vectors for gene transfer are discussed.

A new epitope on sheep CD45R molecule detected by a monoclonal antibody

This paper describes the production and characterization of a monoclonal antibody (mAb), Co-46D5, which recognizes a new epitope on the isoform of the homologous sheep leukocyte common antigen (LCA) or CD45. This nmAb was submitted to the 3rd workshop on ruminant leukocyte antigens and was assigned to a cluster reactive with B- and T-cells subsets. Co-46D recognizes a 220 kDa molecule on peripheral blood mononuclear cells (PBMC) and spleen cells but not on thymocytes. Flow cytometry (FCM) analysis shows that Co-46D5 reacted with 30% of PBMC and 50% of spleen cells and more than 95% of cells freshly isolated from lymphoid follicles of the ileal Peyer's patches (IPP) of young lambs. By immunohistochemistry, the antigen was detected mainly on B-cell areas of lymph nodes and spleen. It was also found on a subpopulation of medullar thymocytes. Based on these results, we assume that Co-46D5 recognizes a new epitope on the largest isoform of the sheep CD45 receptor, probably on the homologous to the human CD45RA isoform.

Defining responsiveness of avian cochlear neurons to brain-derived neurotrophic factor and nerve growth factor by HSV-1-mediated gene transfer

The importance of individual members of the neurotrophin gene family for avian inner ear development is not clearly defined. Here we address the role of two neurotrophins, brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), for innervation of the chicken cochlea. We have used defective herpes simplex virus type 1 (HSV-1) vectors, or amplicons, to express these neurotrophins in dissociated cultures of cochlear neurons. HSV-1-mediated expression of BDNF promotes neuronal survival similar to the maximal level seen by exogenously added BDNF and exceeds its potency to produce neurite outgrowth. In contrast, cochlear neurons transduced with an amplicon producing bioactive NGF show no response. These results confirm BDNF as an important mediator of neurotrophin signaling inside avian cochlear neurons. However, these neurons can be rendered NGF-responsive by transducing them with the high-affinity receptor for NGF, TrkA. This study underlines the usefulness of amplicons to study and modify neurotrophin signaling inside neurons.

Amyloid precursor protein proteoglycan is increased after brain damage

The beta-amyloid peptide (Abeta or A4) is produced by proteolytic cleavage from amyloid precursor protein (APP). The progressive cerebral deposition of this peptide is one of the most important features of Alzheimer's disease. From the study of normal and transfected cells, two APP processing pathways have been proposed as physiological alternatives. One of these can produce Abeta or amyloidogenic peptides, whereas the second does not. However, it is not completely clear how APPs are post-translationally modified, proteolytically processed and metabolized in the brain. We report here that APPs also exist as proteoglycan, chondroitin-sulfate (ChS). We have identified in normal rat brain a complex pool of 8 to 130 kDa ChS-core proteins. The main portion of these proteoglycan (PGs) APPs contains complete amyloidogenic sequence, suggesting a novel proteolytic processing of APP from the amino-terminal to the transmembrane region. This population appears augmented after brain damage. These findings may have significant implications in understanding the initial deposition and kinetics of amyloid aggregation in a pathological situation like Alzheimer's disease.

Competitive sorption of heavy metal by soils. Isotherms and fractional factorial experiments

Competing ions strongly affect heavy metal sorption onto the solid surfaces of soil. This study evaluated competitive sorption of Cd, Cu, Ni, Pb and Zn on three soils: Calcixerollic Xerochrept, Paralithic Xerorthent and Lithic Haplumbrept. Monometal and competitive sorption isotherms were obtained at 25 degrees C. The individual effect of ions on retention of the others was ascertained by a fractional factorial analysis design. Most of the sorption isotherms belonged to type L subtype 2 in the classification of Giles. In competitive sorption the initial linear part was shorter and the knee sharper when compared with monometal sorption isotherms. Parameters related to sorptive capacity, such as Point B, Langmuir monolayer and Freundlich distribution coefficient, were higher in monometal than in competitive sorption, and in basic soils than in acidic soil. Calcium desorbed at different points of the sorption isotherms indicated that cationic exchange with Ca was the main retention mechanism in calcareous soils. For Pb, the ratio Ca desorbed/Pb sorbed was close to one; for Cu, Ni and Zn the ratio ranged from 1.20 to 1.37, probably due to partial dissolution of calcium carbonates by hydrolytic processes during retention. On the other hand, Cd had a ratio around 0.6 reflecting another additional retention mechanism, probably surface complexation. Fractional factorial design confirmed that the presence of the cations investigated reduced the amount of the five metals retained, but the presence of Cu and Pb in the system depressed Ni, Cd and Zn sorption more than the inverse. Cation mobility was enhanced when equilibrium concentration increased and the effect was higher in Ca-saturated soils.

Platelet activation studies with anti-CD41/61 monoclonal antibodies

The purpose of this study was to monitor platelet activation by following alpha IIb beta 3 integrin (GpIIb/IIIa complex or CD41/CD61) on the platelet surface by flow cytometry (FCM) analysis using workshop mAbs. The results obtained with the mAbs showed increased expression of the GpIIb/IIIa complex (about 40%) on the platelet membrane surface under thrombin stimulation.

Distinct tissue distribution in pigs of tenascin-X and tenascin-C transcripts

Tenascin-X and tenascin-C glycoproteins are phylogenetically conserved components of the extracellular matrix, although their specific roles remain to be determined. cDNA probes were produced from pig tenascin-X and tenascin-C genes and were used to examine the tissue distribution of the transcripts in 28 tissues from Large-White pigs, 4.5-42-months old (called adults) and 17 tissues from 87-day-old fetuses. The hybridization of Northern blots with tenascin-X probes revealed, in most tissues, a complex pattern of bands including a major band of about 13 kb, assumed to correspond to the main tenascin-X transcript. Hybridization with the tenascin-C probe showed two transcripts of 6.8 kb and 8.2 kb. The data from the ribonuclease-protection technique showed that both genes displayed large variations in the transcription levels among the tissues analysed. Overall, the tenascin-X gene was significantly expressed in two thirds of the tissues, and the tenascin-C gene in about 50% of them. The highest tenascin-X signals were observed in tendons, ligaments and, unexpectedly, in peripheral nerves. Other tissues, including colon, dermis, skin, heart, uterus, stomach, jejunum, placentae, aorta, lung, mammary and adrenal glands also exhibited significant signal intensities. In fetuses, mainly testes and skeletal muscle showed higher transcription levels than the adult counterparts. The tenascin-C gene was predominantly transcribed in the ligament, tendon, adrenal gland and colon, and more weakly in the stomach, jejunum, lung and spinal cord. In fetuses, the tenascin-C signal in the brain was higher than the signal in the brain of adult, whereas the reverse was true for the adrenal gland and the colon. Within a given tissue, the level of tenascin-X and tenascin-C transcripts varied greatly, indicating independent tenascin-X and tenascin-C transcription regulation mechanisms; this was particularly obvious in adult and fetal nerves but also in the dermis, skin, heart, uterus, placentae and aorta, where tenascin-X RNA molecules were much more abundant than those of tenascin-C. In addition, similar differences were observed in the skeletal muscle and adrenal gland of fetuses. In contrast, the amount of tenascin-C transcripts in the fetal brain and adult spinal cord was higher than those for tenascin-X. Our results draw attention to a possible specific role of tenascin-X in the peripheral nerve physiology.

Stimulation of phagocytic function in mouse macrophages by neurotensin and neuromedin N

The neuropeptides neurotensin and neuromedin N (from 10(-12) M to 10(-9) M) have been shown in this study to stimulate significantly in vitro several steps of the phagocytic process: adherence to substrate, chemotaxis, ingestion of inert particles (latex beads) and production of superoxide anion measured by nitroblue tetrazolium reduction in resting peritoneal macrophages from BALB/c mice. A dose-response relationship was observed, with a maximal stimulation of the phagocytic process at 10(-11) M. The two neuropeptides induced no change of intracellular cyclic AMP in murine macrophages. Moreover, adherence and chemotaxis decreased significantly in the presence of EGTA (1 mM), a chelator of extracellular Ca2+, or ryanodine (0.5 mM), a blocker of a Ca(2+)-gated channel from the endoplasmic reticulum, in both controls and samples with the addition of neurotensin or neuromedin N. These results suggest that there is no relation between the cAMP messenger system and the phagocytic process stimulation in murine peritoneal macrophages by neurotensin or neuromedin N. In addition, the results observed with EGTA and ryanodine could indicate that these two neuropeptides produce their effects through an increase of intracellular Ca2+ concentration.

Modulation by neurotensin and neuromedin N of adherence and chemotaxis capacity of murine lymphocytes

The action of neurotensin and related peptides has not been yet studied on lymphocytes, although there are studies indicating the stimulative action of neurotensin, a peptide first isolated from bovine hypothalamus, on different functions of phagocytic immune cells. The present study demonstrates that neurotensin and a related peptide, neuromedin N, increased significantly the adherence and chemotaxis capacity of murine peritoneal lymphocytes, when they were incubated in the presence of neuropeptide concentrations between 10(-9) M and 10(-12) M. With respect to their adherence capacity, neuromedin N showed a slightly higher stimulation than neurotensin at a shorter time. However, both neuropeptides stimulated the chemotaxis capacity in a similar percentage. The study of the action mechanisms of these neuropeptides showed that intracellular cAMP levels were not modified by neurotensin or neuromedin N, but using an extracellular calcium chelator, EGTA (1 mM), and a blocker of calcium channels in endoplasmic reticulum, ryanodine (0.5 mM), we observed that neurotensin and neuromedin N could produce their effects through an augmentation of the intracellular Ca2+ concentration. As adherence and chemotaxis are initial processes of immune response, the results show that both neuropeptides may be physiological modulators of the lymphocyte function.

Tolerance to 1-pentene-3-ol and to 1-pentene-3-one in relation to alcohol dehydrogenase (ADH) and aldo keto reductase (AKR) activities in Drosophila melanogaster

The detoxification of 1-pentene-3-ol (pentenol) and 1-pentene-3-one (pentenone) by Drosophila melanogaster adult flies has been studied in two homozygous lines for the AdhF and AdhS alleles (LRC lines), in their respective lines selected for tolerance to ethanol (LRSe lines) and in a homozygous strain for the Adhn4 null allele. For each line, the genotype and sex LDs50 of both compounds were estimated. Then, in order to explain the differences in LD50, both alcohol dehydrogenase (ADH) and aldo keto reductase (AKR) activities were assayed. In addition, the effects of pentenone on AKR activity were also studied. Our results show that ADH-positive flies exhibit a much higher sensitivity to pentenol than ADH-null flies. However, both ADH-positive and ADH-null flies show a similar tolerance to pentenone. Our results show that flies selected for improving tolerance to ethanol also have increased tolerance to pentenol (FF and SS flies) and pentenone (SS flies). However, this improved ability to tolerate pentenol and/or pentenone cannot be explained by changes in ADH or AKR activities. On the other hand, we have observed a beneficial effect of pentenol, but not of pentenone, in n4 flies. We also show that AKR activity is not modified by the administration of pentenone. These results suggest that, in the absence of ADH activity, pentenol may be transformed into a compound that is less toxic than pentenone and that pentenone itself might also be transformed into a less toxic compound.

Participation of Drosophila melanogaster alcohol dehydrogenase (ADH) in the detoxification of 1-pentene-3-ol and 1-pentene-3-one

The participation of the ADH enzymes in the detoxification by D. melanogaster of 1-pentene-3-ol (also called pentenol) and its oxidized product, 1-pentene-3-one (usually known as ethyl-vinyl-ketone or pentenone) have been studied using the LR lines. For this purpose flies of AdhS AdhS (SS) and AdhF AdhF (FF) genotypes were independently pretreated with a 2 per cent isopropanol (2-propanol) solution and the survivors exposed to water, to a 0.0075 per cent pentenol solution or to a 0.00375 per cent pentenone solution. After one day in these solutions, the ability to tolerate both compounds was checked and the ADH activity of the surviving flies was measured and compared with those of control flies not pretreated with isopropanol. Additionally, the effects of pentenone on ADH enzymes have been studied by comparing them with those of acetone. Our results show that, in contrast to acetone, pentenone neither reduced significantly the ADH activity in vivo nor altered the normal proportion of ADH isozymes of either SS or FF flies. Our findings also demonstrate that the isopropanol pretreatment implied a considerable decrease in sensitivity not only to pentenol (60 and 91 per cent for SS and FF flies, respectively) but also to pentenone (72 and 80 per cent for SS and FF flies, respectively). After isopropanol pretreatment, FF flies continued exhibiting higher ADH activities than SS ones. However, FF pretreated flies displayed higher tolerance to pentenol and a similar tolerance to pentenone than SS animals. Our results suggest that pentenol (unsaturated secondary alcohol) and isopropanol (saturated secondary alcohol) may be detoxified by slightly different processes (both ADH-activity-dependent), and that pentenone could not be accumulated in the fly but transformed into another compound(s) by means of some ADH-independent mechanism(s).

Intergenotypic effect of isopropanol ingestion in the further detoxification of ethanol and isopropanol in Drosophila melanogaster

The effect of isopropanol ingestion on a further tolerance to ethanol and isopropanol, and its relationship with the Adh locus, have been studied using Drosophila melanogaster selected for tolerance to ethanol. For this purpose, AdhF AdhF, AdhF AdhS and AdhS AdhS flies were independently pretreated with 2 per cent isopropanol and then further exposed to solutions of 10 per cent ethanol or of 2 per cent isopropanol. Afterwards, the ability to tolerate both alcohols, and the ADH activities of the surviving flies were compared with those of flies not pretreated with isopropanol. After isopropanol ingestion, the flies of all three Adh genotypes shown much higher sensitivity to ethanol than to isopropanol although the opposite results were observed in flies not pretreated with isopropanol. Isopropanol treatment decreased the ADH activity in flies of all three genotypes within a range varying from 73 per cent (females FF) to 93 per cent (males FS), the remaining ADH activity being between 2 to 3 times higher in FF than in FS and SS flies. The reduction in ADH activity was associated with the phenomenon of ADH isozyme interconversion. After the isopropanol pretreatment, the most isopropanol tolerant flies (FF) were also the most ADH active ones. Therefore, the adaptative significance of the isozyme conversion is questioned.