The cuticle: Not only a barrier for plant defence: A novel defence syndrome in plants with cuticular defects.

The cuticle is a physical barrier that prevents water loss and protects against irradiation, xenobiotics and pathogens. This classic textbook statement has recently been revisited and several observations were made showing that this dogma falls short of being universally true. Both transgenic Arabidopsis thaliana lines expressing cell wall-targeted fungal cutinase (so-called CUTE plants) or lipase as well as several A. thaliana mutants with altered cuticular structure remained free of symptoms after an inoculation with Botrytis cinerea. The alterations in cuticular structure lead to the release of fungitoxic substances and changes in gene expression that form a multifactorial defence response. Several models to explain this syndrome are discussed.

Tensile strength characteristics of polypropylene composites reinforced with stone groundwood fibers from softwood

The behavior of stone groundwood / polypropylene injection-molded composites was evaluated with and without coupling agent. Stone groundwood (SGW) is a fibrous material commonly prepared in a high yield process and mainly used for papermaking applications. In this work, the use of SGW fibers was explored as a reinforcing element of polypropylene (PP) composites. The surface charge density of the composite components was evaluated, as well as the fiber’s length and diameter inside the composite material. Two mixing extrusion processes were evaluated, and the use of a kinetic mixer, instead of an internal mixer, resulted in longer mean fiber lengths of the reinforcing fibers. On the other hand, the accessibility of surface hydroxyl groups of stone groundwood fibers was improved by treating the fibers with 5% of sodium hydroxide, resulting in a noticeable increase of the tensile strength of the composites, for a similar percentage of coupling agent. A new parameter called Fiber Tensile Strength Factor is defined and used as a baseline for the comparison of the properties of the different composite materials. Finally the competitiveness of stone groundwood / polypropylene / polypropylene-co-maleic anhydride system, which compared favorably to sized glass-fiber / polypropylene GF/PP and glass-fiber / polypropylene / polypropylene-co-maleic anhydride composite formulations, was quantified by means of the fiber tensile strength factor

The biochemistry of drug metabolism--an introduction: part 5. Metabolism and bioactivity.

This review continues a general presentation of the metabolism of drugs and other xenobiotics begun in five recent issues of Chemistry & Biodiversity. The present Part is dedicated to the pharmacological and toxicological consequences of drug and xenobiotic metabolism. In other words, the key concepts here are activation vs. deactivation, toxification vs. detoxification, and their interplay. These concepts are illustrated with a number of medicinally, toxicologically, and environmentally relevant examples. But, far from being concerned only with individual cases, the review is based on broad classifications, global rationalizations, and synthetic hypotheses.

Control of the peroxisomal beta-oxidation pathway by a novel family of nuclear hormone receptors.

Three novel members of the Xenopus nuclear hormone receptor superfamily have been cloned. They are related to each other and similar to the group of receptors that includes those for thyroid hormones, retinoids, and vitamin D3. Their transcriptional activity is regulated by agents causing peroxisome proliferation and carcinogenesis in rodent liver. All three Xenopus receptors activate the promoter of the acyl coenzyme A oxidase gene, which encodes the key enzyme of peroxisomal fatty acid beta-oxidation, via a cognate response element that has been identified. Therefore, peroxisome proliferators may exert their hypolipidemic effects through these receptors, which stimulate the peroxisomal degradation of fatty acids. Finally, the multiplicity of these receptors suggests the existence of hitherto unknown cellular signaling pathways for xenobiotics and putative endogenous ligands.

Physiological function of PARbZip circadian clock-controlled transcription factors.

PARbZip proteins (proline and acidic amino acid-rich basic leucine zipper) represent a subfamily of circadian transcription factors belonging to the bZip family. They are transcriptionally controlled by the circadian molecular oscillator and are suspected to accomplish output functions of the clock. In turn, PARbZip proteins control expression of genes coding for enzymes involved in metabolism, but also expression of transcription factors which control the expression of these enzymes. For example, these transcription factors control vitamin B6 metabolism, which influences neurotransmitter homeostasis in the brain, and loss of PARbZip function leads to spontaneous and sound-induced epilepsy that are frequently lethal. In liver, kidney, and small intestine, PAR bZip transcription factors regulate phase I, II, and III detoxifying enzymes in addition to the constitutive androstane receptor (CAR), one of the principal sensors of xenobiotics. Indeed, knockout mice for the three PARbZip transcription factors are deficient in xenobiotic detoxification and display high morbidity, high mortality, and accelerated aging. Finally, less than 20% of these animals reach an age of 1 year. Accumulated evidences suggest that PARbZip transcription factors play a role of relay, coupling circadian metabolism of xenobiotic and probably endobiotic substances to the core clock circuitry of local circadian oscillators.

Estrogenic activity assessment of environmental chemicals using in vitro assays: identification of two new estrogenic compounds.

Environmental chemicals with estrogenic activities have been suggested to be associated with deleterious effects in animals and humans. To characterize estrogenic chemicals and their mechanisms of action, we established in vitro and cell culture assays that detect human estrogen receptor [alpha] (hER[alpha])-mediated estrogenicity. First, we assayed chemicals to determine their ability to modulate direct interaction between the hER[alpha] and the steroid receptor coactivator-1 (SRC-1) and in a competition binding assay to displace 17ss-estradiol (E(2)). Second, we tested the chemicals for estrogen-associated transcriptional activity in the yeast estrogen screen and in the estrogen-responsive MCF-7 human breast cancer cell line. The chemicals investigated in this study were o,p'-DDT (racemic mixture and enantiomers), nonylphenol mixture (NPm), and two poorly analyzed compounds in the environment, namely, tris-4-(chlorophenyl)methane (Tris-H) and tris-4-(chlorophenyl)methanol (Tris-OH). In both yeast and MCF-7 cells, we determined estrogenic activity via the estrogen receptor (ER) for o,p'-DDT, NPm, and for the very first time, Tris-H and Tris-OH. However, unlike estrogens, none of these xenobiotics seemed to be able to induce ER/SRC-1 interactions, most likely because the conformation of the activated receptor would not allow direct contacts with this coactivator. However, these compounds were able to inhibit [(3)H]-E(2) binding to hER, which reveals a direct interaction with the receptor. In conclusion, the test compounds are estrogen mimics, but their molecular mechanism of action appears to be different from that of the natural hormone as revealed by the receptor/coactivator interaction analysis.

Reprogramming of human fibroblasts to induced pluripotent stem cells under xeno-free conditions

The availability of induced pluripotent stem cells (iPSCs)has created extraordinary opportunities for modeling andperhaps treating human disease. However, all reprogrammingprotocols used to date involve the use of products of animal origin. Here, we set out to develop a protocol to generate and maintain human iPSC that would be entirelydevoid of xenobiotics. We first developed a xeno-free cellculture media that supported the long-term propagation of human embryonic stem cells (hESCs) to a similar extent as conventional media containing animal origin products or commercially available xeno-free medium. We also derivedprimary cultures of human dermal fibroblasts under strictxeno-free conditions (XF-HFF), and we show that they can be used as both the cell source for iPSC generation as well as autologous feeder cells to support their growth. We also replaced other reagents of animal origin trypsin, gelatin, matrigel) with their recombinant equivalents. Finally, we used vesicular stomatitis virus G-pseudotyped retroviral particles expressing a polycistronic construct encoding Oct4, Sox2, Klf4, and GFP to reprogram XF-HFF cells under xeno-free conditions. A total of 10 xeno-free humaniPSC lines were generated, which could be continuously passaged in xeno-free conditions and aintained characteristics indistinguishable from hESCs, including colonymorphology and growth behavior, expression of pluripotency-associated markers, and pluripotent differentiationability in vitro and in teratoma assays. Overall, the resultspresented here demonstrate that human iPSCs can be generatedand maintained under strict xeno-free conditions and provide a path to good manufacturing practice (GMP) applicability that should facilitate the clinical translation of iPSC-based therapies.

Structural development of the Tso Morari ultra-high pressure nappe of the Ladakh Himalaya

A continental subduction-related and multistage exhumation process for the Tso Morari ultra-high pressure nappe is proposed. The model is constrained by published thermo-barometry and age data, combined with new geological and tectonic maps. Additionally, observations on the structural and metamorphic evolution of the Tso Morari area and the North Himalayan nappes are presented. The northern margin of the Indian continental crust was subducted to a depth of >90 km below Asia after continental collision some 55 Ma ago. The underthrusting was accompanied by the detachment and accretion of Late Proterozoic to Early Eocene sediments, creating the North Himalayan accretionary wedge, in front of the active Asian margin and the 103-50 Ma Ladakh arc batholith. The basic dikes in the Ordovician Tso Morari granite were transformed to eclogites with crystallization of coesite, some 53 Ma ago at a depth of >90 kin (>27 kbar) and temperatures of 500 to 600 degrees C. The detachment and extrusion of the low density Tso Morari nappe, composed of 70% of the Tso Morari granite and 30% of graywackes with some eclogitic dikes, occurred by ductile pure and simple shear deformation. It was pushed by buoyancy forces and by squeezing between the underthrusted Indian lithosphere and the Asian mantle wedge. The extruding Tso Morari nappe reached a depth of 35 km at the base of the North Himalayan accretionary wedge some 48 Ma ago. There the whole nappe stack recrystallized under amphibolite facies conditions of a Barrovian regional metamorphism with a metamorphic field gradient of 20 degrees C/km. An intense schistosity with a W-E oriented stretching lineation L, and top-to-the E shear criteria and crystallization of oriented sillimanite needles after kyanite, testify to the Tso Morari nappe extrusion and pressure drop. The whole nappe stack, comprising from the base to top the Tso Morari, Tetraogal, Karzok and Mata-Nyimaling-Tsarap nappes, was overprinted by new schistosities with a first N-directed and a second NE-directed stretching lineation L-2 and L-3 reaching the base of the North Himalayan accretionary wedge. They are characterized by top-to-the S and SW shear criteria. This structural overprint was related to an early N- and a younger NE-directed underthrusting of the Indian plate below Asia that was accompanied by anticlockwise rotation of India. The warping of the Tso Morari dome started already some 48 Ma ago with the formation of an extruding nappe at depth. The Tso Morari dome reached a depth of 15 km about 40 Ma ago in the eastern Kiagar La region and 30 Ma ago in the western Nuruchan region. The extrusion rate was of about 3 cm/yr between 53 and 48 Ma, followed by an uplift rate of 1.2 mm/yr between 48 and 30 Ma and of only 0.5 mm/yr after 30 Ma. Geomorphology observations show that the Tso Morari dome is still affected by faults, open regional dome, and basin and pull-apart structures, in a zone of active dextral transpression parallel to the Indus Suture zone.

Regional variations in ABC transporter expression along the mouse intestinal tract.

The ATP-binding cassette (ABC) family of proteins comprise a group of membrane transporters involved in the transport of a wide variety of compounds, such as xenobiotics, vitamins, lipids, amino acids, and carbohydrates. Determining their regional expression patterns along the intestinal tract will further characterize their transport functions in the gut. The mRNA expression levels of murine ABC transporters in the duodenum, jejunum, ileum, and colon were examined using the Affymetrix MuU74v2 GeneChip set. Eight ABC transporters (Abcb2, Abcb3, Abcb9, Abcc3, Abcc6, Abcd1, Abcg5, and Abcg8) displayed significant differential gene expression along the intestinal tract, as determined by two statistical models (a global error assessment model and a classic ANOVA, both with a P < 0.01). Concordance with semiquantitative real-time PCR was high. Analyzing the promoters of the differentially expressed ABC transporters did not identify common transcriptional motifs between family members or with other genes; however, the expression profile for Abcb9 was highly correlated with fibulin-1, and both genes share a common complex promoter model involving the NFkappaB, zinc binding protein factor (ZBPF), GC-box factors SP1/GC (SP1F), and early growth response factor (EGRF) transcription binding motifs. The cellular location of another of the differentially expressed ABC transporters, Abcc3, was examined by immunohistochemistry. Staining revealed that the protein is consistently expressed in the basolateral compartment of enterocytes along the anterior-posterior axis of the intestine. Furthermore, the intensity of the staining pattern is concordant with the expression profile. This agrees with previous findings in which the mRNA, protein, and transport function of Abcc3 were increased in the rat distal intestine. These data reveal regional differences in gene expression profiles along the intestinal tract and demonstrate that a complete understanding of intestinal ABC transporter function can only be achieved by examining the physiologically distinct regions of the gut.

Contribution of in vitro neurotoxicology studies to the elucidation of neurodegenerative processes.

Only a small percentage of neurodegenerative diseases like Alzheimer's disease and Parkinson's disease is directly related to familial forms. The etiology of the most abundant, sporadic forms seems to involve both genetic and environmental factors. Environmental compounds are now extensively studied for their possible contribution to neurodegeneration. Chemicals were found which were able to reproduce symptoms of known neurodegenerative diseases, others may either predispose to the onset of neurodegeneration, or exacerbate distinct pathogenic processes of these diseases. In any case, in vitro studies performed with models presenting various degrees of complexity have shown that many environmental compounds have the potential to cause neurodegeneration, through a variety of pathways similar to those described in neurodegenerative diseases. Since the population is exposed to a huge number of potentially neurotoxic compounds, there is an important need for rapid and efficient procedures for hazard evaluation. Xenobiotics elicit a cascade of reactions that, most of the time, involve numerous interactions between the different brain cell types. A reliable in vitro model for the detection of environmental toxins potentially at risk for neurodegenerative diseases should therefore allow maximal cell-cell interactions and multiparametric endpoints determination. The combined use of in vitro models and new analytical approaches using "omics" technologies should help to map toxicity pathways, and advance our understanding of the possible role of xenobiotics in the etiology of neurodegenerative diseases.

Thrusting, extension, and doming during the polyphase tectonometamorphic evolution of the High Himalayan Crystalline Zone in NW India

In the NW Himalaya of India, high-grade metamorphic rocks of the High Himalayan Crystalline Zone (HHCZ) are exposed as a 50 km large dome along the Miyar and Gianbul valleys. This Gianbul dome is cored by migmatitic paragneiss formed at peak conditions around 750 degreesC and 8 kbar, and symmetrically surrounded by sillimanite, kyanite +/- staurolite, garnet, biotite, and chlorite Barrovian mineral zones. Thermobarometric and structural investigations reveal that the Gianbul dome results from a polyphase tectono-metamorphic evolution. The first phase corresponds to the NE-directed thrusting of the Shikar Beh nappe, that is responsible for the Barrovian prograde metamorphic field gradient in the southern limb of the dome. In the northern limb of the dome, the Barrovian prograde metamorphism is the consequence of a second tectonic phase, associated with the SW-directed thrusting of the Nyimaling-Tsarap nappe. Following these crustal thickening events, exhumation and doming of the HHCZ high-grade rocks were controlled by extension along the north-dipping Zanskar Shear Zone, in the frontal part of the Nyimaling-Tsarap nappe, as well as by coeval to late extension along the south-dipping Khanjar Shear Zone, in the southern limb of the Gianbul dome. Rapid syn-convergence extension along both of these detachments induced a nearly isothermal decompression, resulting in a high-temperature/low-pressure metamorphic overprint, as well as enhanced partial melting. Such a rapid exhumation within a compressional orogenic context appears unlikely to be controlled solely by granitic diapirism. Alternatively, large-scale doming in the Himalaya could reflect a sub-vertical ductile extrusion of partially melted rocks.

Workgroup report: incorporating in vitro alternative methods for developmental neurotoxicity into international hazard and risk assessment strategies.

This is the report of the first workshop on Incorporating In Vitro Alternative Methods for Developmental Neurotoxicity (DNT) Testing into International Hazard and Risk Assessment Strategies, held in Ispra, Italy, on 19-21 April 2005. The workshop was hosted by the European Centre for the Validation of Alternative Methods (ECVAM) and jointly organized by ECVAM, the European Chemical Industry Council, and the Johns Hopkins University Center for Alternatives to Animal Testing. The primary aim of the workshop was to identify and catalog potential methods that could be used to assess how data from in vitro alternative methods could help to predict and identify DNT hazards. Working groups focused on two different aspects: a) details on the science available in the field of DNT, including discussions on the models available to capture the critical DNT mechanisms and processes, and b) policy and strategy aspects to assess the integration of alternative methods in a regulatory framework. This report summarizes these discussions and details the recommendations and priorities for future work.

The biochemistry of drug metabolism : an introduction : part 6, Inter-individual factors affecting drug metabolism.

This review is part of a series of review articles on the metabolism of drugs and other xenobiotics published in Chemistry & Biodiversity. After a thorough discussion of metabolic reactions and their enzymes, this article focuses on genetically determined differences in drug and xenobiotic metabolism. After a short introduction on the causes for genetic differences, the first focus is on species differences in drug and xenobiotic metabolism. A major chapter is then dedicated to clinically relevant genetic polymorphisms in human drug metabolism and resultant ethnic differences. The last two chapters deal with sex-dependent differences in drug metabolism and personalized pharmacotherapy related to inter-individual differences in drug metabolism.

Combined Electrostatic and Covalent Polymer Networks for Cell Microencapsulation

Two types of hydrogel microspheres have been developed. Fast ionotropic gelation of sodium alginate (Na-alg) in the presence of calcium ions was combined with slow covalent cross-linking of poly(ethylene glycol) (PEG) derivatives. For the first type, the fast obtainable Ca-alg hydrogel served as spherical matrix for the simultaneously occurring covalent cross-linking of multi-arm PEG derivative. A two-component interpenetrating network was formed in one step upon extruding the mixture of the two polymers into the gelation bath. For the second type, heterobifunctional PEG was grafted onto Na-alg prior to gelation. Upon extrusion of the polymer solution into the gelation bath, fast Ca-alg formation ensured the spherical shape and was accompanied by cross-linker-free covalent cross-linking of the PEG side chains. Thus, one-component hydrogel microspheres resulted. We present the physical properties of the hydrogel microspheres and demonstrate the feasibility of cell microencapsulation for both types of polymer networks.

Structural and magnetic characterization of the lithiated iron oxide LixFe3O4

The Rietveld profile‐analysis method is used to investigate the x‐ray diffraction pattern of lithiated Fe3O4. It is shown that, after exposure to air, pure magnetite coexists with a lithium‐inserted LixFe3O4 phase. The Mössbauer spectra at 300 and 4.2 K have been used to estimate the lithium content of the sample, the pure magnetite concentration, and the iron distribution over the available 16c and 16d sites of the spinel structure. Magnetization measurements from 4.2 to 120 K with an external magnetic field up to 150 kOe have been used to obtain the saturation magnetic moment, the magnetic anisotropy constants, and the susceptibility. It is concluded that a noncollinear spin structure should be present in Li0.5Fe3O4. These results indicate that there is no room‐temperature extrusion of iron even for x→2.0, but that on exposure to air LixFe3O4 samples with x>0.5 are oxidized at room temperature by delithiation.