Anodic Polymerization of Phenylphenols in Methyl Isobutyl Ketone and Mesityl Oxide: Incorporation of a Cavitand into the Layers Formed for Sensing Phenols in Organic Media.

The electropolymerization of three phenylphenol isomers was studied in methyl isobutyl ketone and mesityl oxide, and the remarkable differences highlighted the importance of the carbon-carbon double bond in mesityl oxide. In the case of each substrate, a brownish deposit formed during the electrooxidation. The obvious difference between the polymers formed from the two solvents was recognized via voltammetric signal enhancement of 4-methoxyphenol and 4-chlorophenol, and it was only observed in the case of mesityl oxide. The experiments highlighted that incorporation of a cavitand with biphenyl groups on the upper rim of the polymers of phenylphenols improved the results to a small extent. The cavitand was, itself, electroactive without any fouling effect. As 2-phenylphenol is by far the cheapest of the three isomers, a cavitand was incorporated into its polymer, which was exploited to solve analytical problems while mesityl oxide was used as solvent. Useful quantifications were achieved in organic solvents; however, it failed under aqueous conditions due to the high hydrophobicity of the deposit. Application of differential pulse voltammetry for 4-methoxyphenol and 4-chlorophenol gave detection limits of 9.28 and 50.8 µM in acetonitrile, respectively. This procedure resulted in the immobilization of cavitand derivatives onto the electrode's surface, and the layer formed offered selective sensing of phenols by electrochemical methods.

Changes of cytoskeletal proteins in nerve tissues and serum of rats treated with 2,5-hexanedione.

To investigate the mechanisms and biomarker of the neuropathy induced by 2,5-hexanedione (HD), male Wistar rats were administrated HD at dosage of 200 or 400mg/kg for 8 weeks (five-times per week). All rats were sacrificed after 8 weeks of treatment and the cerebrum cortex (CC), spinal cord (SC) and sciatic nerves (SN) were dissected, homogenized and used for the determination of cytoskeletal proteins by western blotting. The levels of neurofilaments (NFs) subunits (NF-L, NF-M and NF-H) in nerve tissues of 200 and 400mg/kg HD rats significantly decreased in both the supernatant and pellet fractions. Furthermore, significant negative correlations between NFs levels and gait abnormality were observed. As for microtubule (MT) and microfilament (MF) proteins, the levels of alpha-tubulin, beta-tubulin and beta-actin in the supernatant and pellet fraction of SN significantly decreased in 200 and 400mg/kg HD rats and correlated negatively with gait abnormality. However, the contents of MT and MF proteins in CC and SC were inconsistently affected and had no significant correlation with gait abnormality. The levels of NF-L and NF-H in serum significantly increased, while NF-M, alpha-tubulin, beta-tubulin and beta-actin contents remain unchanged. A significant positive correlation (R=0.9427, P<0.01) was observed between gait abnormality and NF-H level in serum as the intoxication went on. These findings suggested that HD intoxication resulted in a progressive decline of cytoskeletal protein contents, which might be relevant to the mechanisms of HD-induced neuropathy. NF-H was the most sensitive index, which may serve as a good indicator for neurotoxicity of n-hexane or HD.

Synthesis of jet fuel range branched cycloalkanes with mesityl oxide and 2-methylfuran from lignocellulose.

Jet fuel range branched cycloalkanes with high density (0.82 g mL(-1)) and low freezing point (217-219 K) was first prepared by the solvent-free intramolecular aldol condensation of the trione from the hydrolysis of the alkylation product of mesityl oxide and 2-methylfuran (or the one-pot reaction of mesityl oxide, 2-methylfuran and water), followed by hydrodeoxygenation (HDO).

Modulation of low-affinity nerve growth factor receptor in injured adult rat spinal cord motoneurons.

Spinal and brainstem motoneurons of the adult rat reexpress low-affinity nerve growth factor receptor (LNGFR) and its mRNA after axotomy. We have previously reported the time courses of this reexpression after cut (no regeneration) or crush (followed by regeneration) of the sciatic nerve. We have shown that the length of the different phases of this reexpression (appearance, maintenance and disappearance) can vary according to the type of axotomy. With the present study we expand our previous data and describe and analyze the modulation the LNGFR expression in adult spinal cord motoneurons following different lesion paradigms. In one approach we have imposed three traumatic injuries that still allow regeneration of the sciatic nerve but with a different time course with respect to the crush injury (application of a silicone regeneration chamber, multiple crushes and delayed repair of ligated nerves). In a second approach, we have determined the capability of three toxic or metabolic injuries to induce LNGFR expression without any direct trauma of the nerve (experimental diabetogenesis, botulinum and alpha-bungarotoxin intoxication and 2,5-hexanedione intoxication). In a third approach, we have investigated the effect of the block of the axoplasmic transport on the LNGFR expression following different topical applications of vincristine combined with a nerve crush. The results we present are consistent with the idea that: (1) LNGFR immunoreactivity in adult motoneurons is expressed by motoneurons that are attending to an axonal outgrowth and not a generic signal of cellular damage or impairment of the motor function; (2) LNGFR expression in these motoneurons is related to and parallels the outgrowth process time frame, and (3) the signal/s that trigger and sustain this reexpression may be retrogradely transported from the periphery.

Differentiation-inducing factor-1 enhances 5-fluorouracil action on oral cancer cells inhibiting E2F1 and thymidylate synthase mRNAs accumulation.

PURPOSE: Differentiation-inducing factor-1 (DIF-1) is a morphogen originally identified in the amoebozoan Dictyostelium discoideum. In mammalian cells, it has been shown to activate GSK3ß, which in turn is expected to reduce levels of ß-catenin and cyclin D1, thus mediating DIF-1 antiproliferative properties. Since this could alter the expression and activity of E2F1 transcription factor and consequently those of the prognostic marker/chemotherapy target thymidylate synthase (TS), we evaluated (1) whether DIF-1 could effectively regulate these genes, (2) whether it could interfere with cell viability, and (3) whether DIF-1 activity could enhance the efficacy of the TS inhibitor 5-fluorouracil (5-FU). METHODS: We investigated the effects of DIF-1 in continuous human cell lines derived from two oral tumor histotypes (corresponding to an adenosquamous and a squamous carcinoma) and a gingival epithelium. We evaluated mRNA accumulation by means of quantitative real-time PCR and efficacy of drugs on cell viability by means of MTT assay. RESULTS: DIF-1 inhibited the accumulation of E2F1 mRNA and reduces TS mRNA levels in tumor cell lines, but did not alter mRNA levels in the gingival counterpart. As a result, it inhibited proliferation preferentially of tumor cell in time- and concentration-dependent manner. Moreover, it enhanced cytotoxic effects of 5-FU only in tumor cell, whereas reduced them in the gingival counterpart. CONCLUSIONS: These findings suggest a tumor-specific action of DIF-1 on oral carcinoma cells. Thus, interfering with E2F1 and TS transcription, DIF-1 potentiates TS enzymatic inhibitors.

Effect of immunomodulators in the hu-PBL-SCID mouse model.

The effects of two immunomodulators were investigated in severe combined immunodeficient mice reconstituted with human peripheral blood lymphocytes (hu-PBL-SCID mice). Both immunomodulators, maleic anhydride divinyl ether (MVE-2) and 4-imino-1,3-diazobicyclo-(3.1.0)-hexan-2- one (imexon), have been previously studied by us in retrovirus-infected mice. To determine the effects of these compounds as they may function in humans, 24 SCID mice were each reconstituted with 20 x 10(6) ficoll-purified lymphocytes from a single donor. Five weeks after reconstitution, the mice received 16 mg/kg/day of MVE-2 intraperitoneally (i.p.) on days 0, 7, and 14 or 110 mg/kg/day of imexon i.p. daily for 14 days. Spleens were removed and splenocytes labeled with monoclonal antibodies for T- and B-cell enumeration as determined by flow cytometry 24 h after final treatment. Imexon-treated mice demonstrated a slight increase in total T cells and T cell subsets compared to control mice. T helper/T suppressor cell ratios in imexon-treated mice were brought to a normal 3:2 ratio compared to placebo-treated mice. Human immunoglobulin levels were markedly increased in imexon-treated mice. MVE-2-treated hu-PBL-SCID mice had significantly reduced numbers of total T cells compared to controls. The T-cell population results using human cells in SCID mice were similar to the effects of these immunomodulators on murine cells in immunologically competent mice.

2,5-Hexanedione alters microtubule assembly. I. Testicular atrophy, not nervous system toxicity, correlates with enhanced tubulin polymerization.

Charles River CD rats (200 g) were divided into three groups receiving either 1% 2,5-hexanedione (2,5-HD) or 0.035% 3,4-dimethyl-2,5-hexanedione (DMHD) in the drinking water or water alone (control) for 4 weeks. The two treated groups experienced similar nervous system dysfunction and systemic toxicity. Testicular toxicity, as evidenced by histological changes and decreased testis weight, was present only in 2,5-HD-treated rats. Tubulin was purified from brain and testis and assembly properties were determined. Purified brain and testis tubulin derived from the 2,5-HD-intoxicated rats displayed altered assembly with a shortened nucleation phase and more rapid rate of elongation. Brain tubulin from DMHD-intoxicated rats displayed assembly behavior similar to controls, while testis tubulin from DMHD-intoxicated rats displayed assembly behavior intermediate between the control and 2,5-HD tubulin preparations. The presence of gamma-diketone-induced assembly alterations following in vivo intoxication was accompanied by the formation of a high-molecular-weight protein identified as crosslinked tubulin. From these data, we conclude that microtubule assembly alterations are not etiologic in the development of nervous system dysfunction following intoxication but may represent the biochemical mechanism of 2,5-HD-induced testicular atrophy.

2,5-Hexanedione alters microtubule assembly. II. Enhanced polymerization of crosslinked tubulin.

The toxic syndrome resulting from in vivo exposure to n-hexane or n-hexane derivatives may, in part, be a manifestation of altered tubulin and microtubule properties. The effect of in vitro gamma-diketone derivatization was first studied using purified bovine brain tubulin and the results were then verified in tubulins purified from target organs of an experimental species. Microtubule assembly and structure were modified after in vitro incubation with 2,5-hexanedione (2,5-HD) as follows: 2,5-HD derivatization of purified tubulin resulted in an alteration in microtubule assembly kinetics, most prominently a decrease in the length of the nucleation phase, the alteration in assembly kinetics was accompanied by the formation of a covalently crosslinked tubulin dimer, mixing experiments which combined different proportions of control and treated tubulin showed that only a small amount of derivatized tubulin need be present to induce altered assembly properties, and as a result of the more rapid nucleation phase, a greater number of nucleating seeds produced more numerous and shorter assembled polymers. In vitro incubation with the 2,5-HD congener 3,4-dimethyl-2,5-hexanedione produced similar alterations in microtubule assembly. Thus, both the kinetics of tubulin polymerization and the morphology of the final assembly product were modified by in vitro gamma-diketone incubation.