Kinetics of chemically mediated neurodegeneration/neuroregeneration of mouse olfactory epithelium: monitoring by hyperlayer sedimentation field flow fractionation

The increase in the incidence of neurodegenerative diseases linked to aging or injury needs to be addressed in research into neuroprotective or neuroregenerative therapies, and requires the development of specific biological models. To achieve this goal we propose (1) the use of the mouse olfactory epithelium as a biological support which specifically exhibits a regenerative or a self-renewing capacity and during the lifetime necessitates the presence of neural stem cells, and (2) the use of an intraperitoneal injection of 2,6-dichlorobenzonitrile (diclobenil) as a chemical inducer of neurodegeneration in olfactory epithelium by selectively killing mature cells. We developed a biological model to follow the processes of neurodegeneration (chemically induced) and neuroregeneration (self-renewal of olfactory epithelium). The purpose of this study was to develop a method to monitor quickly neurodegeneration/neuroregeneration processes in order to further screen protective and regenerative therapies. For this purpose, we used the sedimentation field flow fractionation elution of olfactory epithelium. We obtained specific elution profiles and retention parameters allowing the monitoring of the induction and kinetics of biological processes. The use of insulin-like growth factor 1α as a neuroprotective agent in an innovative nebulization protocol showed sedimentation field flow fractionation to be a simple, fast and low-cost method to monitor such a biological event on the scale of an entire organism.

Measurement of the positive muon lifetime and determination of the Fermi constant to part-per-million precision

We report a measurement of the positive muon lifetime to a precision of 1.0 ppm; it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2×10(12) decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give τ(μ(+)) (MuLan)=2 196 980.3(2.2)  ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G(F) (MuLan)=1.166 378 8(7)×10(-5)  GeV(-2) (0.6 ppm). It is also used to extract the μ(-)p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g(P).

Study of the phenotypic relationship in the IMR-32 human neuroblastoma cell line by sedimentation field flow fractionation

Neuroblastoma (NB) is the most common childhood solid tumor. Although spontaneous regression can occur in patients <1-year old, 70% of patients over the age of 1 year have a high-risk and difficult-to-treat NB. Cell type heterogeneity is observed either in the morphological appearance of NB tumors or in cell lines isolated from tumor specimens. NB consists of two principal neoplastic cell types: i) neuroblastic or N-type (undifferentiated cells); and ii) stromal or S-type (differentiated cells). As NB cells seem to have the capacity to differentiate spontaneously in vivo and in vitro, their heterogeneity could affect treatment outcome, in particular the response to apoptosis induced by chemotherapy. Therefore, it is important to understand the underlying process governing changes in differentiation in order to improve treatment response and NB patient outcome and the neoplastic population in IMR-32 represented a good model for such a study. Results showed that this cell line was extremely heterogeneous and highly variable in its stage of differentiation and we demonstrated that sedimentation field flow fractionation (SdFFF) permitted the isolation of 2 N-phenotypes and contributed to the understanding of the IMR-32 cell population dynamics. The first N-phenotype forms a pool of quiescent undifferentiated cells while the second one was able to proliferate (incorporation of BrdU) and also give rise to adherent S-type cells (PSA-N-CAM+ and N-CAM+). The results could also suggest a close interaction between these different cellular phenotypes to create the IMR-32 cell lineage.

Improved measurement of the positive-muon lifetime and determination of the Fermi constant

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau(micro)=2.197 013(24) micros, is in excellent agreement with the previous world average. The new world average tau(micro)=2.197 019(21) micros determines the Fermi constant G(F)=1.166 371(6)x10(-5) GeV-2 (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling g(P).

A phase II study of pemetrexed in patients (pts) with advanced neuroendocrine tumors (NETs)

15149

Background: Traditional antifolates such as 5-florouracil have been associated with only modest activity in NETs. Pemetrexed is a multitargeted antifolate active in diseases not known to be responsive to other antifolates. We performed a prospective phase II study of pemetrexed in pts with advanced NETs to assess response, toxicity, and survival. Methods: Pts were treated with Pemetrexed administered intravenously at a dose of 500 mg/m2 every 21 days. To reduce toxicity, folic acid and vitamin B12 supplementation were mandatory. Pts were also treated with oral dexamethasone 4 mg twice daily the day prior to, day of, and day after pemetrexed administration. The study utilized a two-step design, with an initial accrual phase of 17. Pts were required to have metastatic neuroendocrine tumors (excluding small cell carcinoma), and preserved hematologic, renal, and hepatic function. Treatment with prior chemotherapy was allowed; pts receiving octreotide remained on octreotide at a stable dose level during study therapy. Results: 17 pts were enrolled with the following characteristics: M: F=4:13. median age 56 (range 38 to 72); ECOG Performance Status 0/1/2=4/12/1. Tumor types included carcinoid n=12(71%) and islet cell n=5(29%). 17 pts received treatment for a median of three, 21-day cycles; the median time on study was 10 weeks. Grade 3–4 toxicities included: fatigue n=8(47%), leukopenia n=7 (41%), neutropenia n=6 (35%), elevated alkaline phosphatase n=4 (23%), thrombocytopenia n=3 (17%), lymphopenia n=3 (17%), pneumonitis n=2 (11%), hyponatremia n=2 (11%), dyspnea n=1 (5%), hyperbilirubinemia n=1 (5%), weight loss n=1 (5%), diarrhea n=1 (5%), elevated ALT/SGPT n=1 (5%), edema n=1 (5%), weakness n=1 (5%), grade 4 proteinuria n=1 (5%). 15 pts were evaluable for response; the best treatment response was stable disease (n=9;), the remaining 6 pts experienced progressive disease as their best response to therapy. Accrual to the study was halted due to lack of observed antitumor activity. Conclusions: Pemetrexed does not have significant antitumor activity in pts with advanced NET.

No significant financial relationships to disclose.

Sedimentation field flow fractionation to study human erythroleukemia cell megakaryocytic differentiation after short period diosgenin induction

Anti-cancer differentiation therapy could be one strategy to stop cancer cell proliferation. We propose a new sedimentation field flow fractionation (SdFFF) cell separation application in the field of cancer research. It concerns the study of megakaryocytic differentiation processes after a short exposure to an inducting agent (diosgenin). Washout process and early dual SdFFF separation--removing the influence of diosgenin and decreasing the influence of undifferentiated cells--resulted in the preparation of an enriched population to study the mechanism and kinetics of megakaryocytic differentiation. A short exposure to diosgenin was able to induce complete differentiation leading to maximal maturation which ended naturally after 192h incubation without the influence of a secondary effect of diosgenin. The study of isolated undifferentiated cells also showed that no resistance to diosgenin was observed. This result suggested different sensitivities to differentiation induction, and SdFFF cell separation would be of great interest to explore this phenomena.

Phase II study of FOLFOX, bevacizumab and erlotinib as first-line therapy for patients with metastatic colorectal cancer

BACKGROUND

Targeting the epidermal growth factor receptor and angiogenesis have proven useful strategies against metastatic colorectal cancer. The benefit of combining inhibitors of both pathways is unknown.

PATIENTS AND METHODS

Patients with previously untreated metastatic colorectal cancer were enrolled in a phase II trial of infusional 5-fluorouracil, leucovorin, oxaliplatin (FOLFOX), bevacizumab and erlotinib. The primary end point was progression-free survival.

RESULTS

Thirty-five patients were enrolled and all came off trial for reasons other than progression; 18 (51%) had protocol-defined adverse events requiring removal, nine (26%) withdrew consent due to toxicity, six pursued surgery or localized therapies and two requested a treatment holiday. Principal toxic effects included rash, neuropathy and diarrhea. Seven patients came off trial before first restaging. By intention-to-treat analysis, one patient had a confirmed complete response, 10 had confirmed partial responses and one had an unconfirmed partial response (response rate = 34%). One patient had progressive disease at time of withdrawal from the trial, thus progression-free survival could not be calculated.

CONCLUSION

The combination of FOLFOX, bevacizumab and erlotinib led to higher than expected early withdrawal due to toxicity, limiting conclusions regarding efficacy. These findings raise concern regarding the tolerability of adding more agents to already complex combination regimens for metastatic colorectal cancer.

Sedimentation field flow fractionation monitoring of bimodal wheat starch amylolysis

Enzymatic starch granule hydrolysis is one of the most important reactions in many industrial processes. In this study, we investigated the capacity of sedimentation field flow fractionation (SdFFF) to monitor the amylolysis of a bimodal starch population: native wheat starch. Results demonstrated a correlation between fractogram changes and enzymatic hydrolysis. Furthermore, SdFFF was used to sort sub-populations which enhanced the study of granule size distribution changes occurring during amylolysis. These results show the interest in coupling SdFFF with particle size measurement methods to study complex starch size/density modifications associated to hydrolysis. These results suggested different applications such as the association of SdFFF with structural investigations to better understand the specific mechanisms of amylolysis or starch granule structure.

Pre-apoptotic sub-population cell sorting from diosgenin apoptosis induced 1547 cells by Sedimentation Field-Flow Fractionation

Apoptosis is one of the most important phenomena in cell biology. Pre-apoptotic cells, defined as cells engaged in early stages of apoptosis, could be used as a cellular tool to study apoptosis pathways. The human 1547 osteosarcoma cell line and diosgenin (a plant steroid) association was selected as an in vitro cellular apoptosis model. In a previous study, using this model, we demonstrated that SdFFF monitored apoptosis induction as early as 6h after incubation. In this study, we investigated the capacity of Sedimentation Field-Flow Fractionation (SdFFF) to sort an enriched population of pre-apoptotic cells from 1547 cells incubated for 6 h with 40 microM diosgenin. In that way, two different separation devices which differed especially in channel thickness, 125 and 175 microm, were used and compared. Results showed, for the first time, that SdFFF is an effective method to obtain an enriched pre-apoptotic sub-population. These results suggest, as a new application, that SdFFF could be an included tool in the study of apoptotic mechanisms or the kinetic action of apoptotic drugs.

Megakaryocyte cell sorting from diosgenin-differentiated human erythroleukemia cells by sedimentation field-flow fractionation

Anticancer differentiation therapy could be one strategy to stop cancer cell proliferation. Human erythroleukemia (HEL) cell line, incubated with 10 microM diosgenin, underwent megakaryocytic differentiation. Thus, the association diosgenin/HEL could be used as a model of chemically induced cellular differentiation and anticancer treatment. The goal of this work was to determine the capacity of sedimentation field-flow fractionation (SdFFF) to sort megakaryocytic differentiated cells. SdFFF cell sorting was associated with cellular characterization methods to calibrate specific elution profiles. As demonstrated by cell size measurement methods, cellular morphology, ploidy, and phenotype, we obtained an enriched, sterile, viable, and functional fraction of megakaryocytic cells. Thus, SdFFF is proposed as a routine method to prepare differentiated cells that will be further used to better understand the megakaryocytic differentiation process.

Neural stem cell separation from the embryonic avian olfactory epithelium by sedimentation field-flow fractionation

The aim of the present study was to isolate neural stem cells from a complex tissue: the avian olfactory epithelium; by using sedimentation field flow fractionation (SdFFF). By using "Hyperlayer" elution mode, fraction collection and cell characterization methods, results shows that SdFFF could be a useful cell sorter to isolate an enriched, viable and sterile immature neural cell fraction from which the reconstitution of a complete epithelium was possible. In culture, SdFFF eluted cells first led to a "pseudoplacodal" epithelioid cell type from which derived "floating cells". These cells were then able to generate neurosphere-like structures which were composed of cell having many features of immature cells: undifferentiated, self-renewable and multipotentiality. Such a population might be used as a model to improve our understanding of the mechanisms of olfactory neoneurogenesis.

Phase II study of FOLFOX, bevacizumab and erlotinib as initial therapy for patients with metastatic colorectal cancer (MCRC)

3545

Background: Cytotoxic chemotherapy with targeted therapy against the vascular endothelial growth factor (VEGF) or the epidermal growth factor receptor (EGFR) has become a standard approach in MCRC, though combining VEGF and EGFR inhibition with chemotherapy as initial treatment is not well established. We conducted a phase II study of the combination of infusional 5-fluorouracil (5-FU), leucovorin, oxaliplatin (FOLFOX), bevacizumab, and erlotinib in chemotherapy naïve patients with MCRC. Methods: Eligible patients had measurable MCRC, no prior systemic therapy for MCRC or at least one year since completion of adjuvant therapy (only 5-FU and leucovorin acceptable), performance status 0–1. The regimen consisted of 14-day cycles of FOLFOX started on day 1 (oxaliplatin 85 mg/m2, bolus 5-FU 400 mg/m2, leucovorin 400 mg/m2 and 46-hour infusion 5-FU 2.4 g/m2), day 1 bevacizumab 5 mg/kg and erlotinib 150 mg daily. This isa single stage trial with goal of 35 patients. The primary endpoint was progression-free survival (PFS). Results: Between Jan and Dec 2005, 31 patients have been enrolled with the following characteristics: male/female, 19/12; PS ECOG 0/1, 15/16; median age 58, range 38–81. Of the 28 patients who completed at least 1 cycle, the most common grade 3/4 adverse events include: 8/28 (29%) diarrhea, 8/28 (29%) neutropenia, 5/28 (18%) rash, 4/28 (14%) fatigue, 3/28 (11%) nausea/vomiting, 3/28 (11%) neuropathy. 22/28 (78%) of patients had at least 1 grade 3/4 toxicity. 14/31 patients remain on trial, 13/31 (42%) came off for toxicity or withdrew consent due to treatment-related toxicities, 4 withdrew consent for other reasons. Efficacy data is not available at time of submission but will be more mature by June 2006. Conclusions: The combination of FOLFOX, bevacizumab and erlotinib appears to have moderate toxicity, with ∼40% of patients coming off trial due to side effects. Further characterization of the tolerability profile will be necessary when interpreting the efficacy of the combination. We expect full accrual as well as reasonable point estimates of PFS by June 2006. Supported by: Sanofi-Synthelabo, a member of the Sanofi-Aventis group, Genentech

[Table: see text]

Sedimentation field flow fractionation monitoring of rice starch amylolysis

Enzymatic starch granule hydrolysis is one of the most important reactions in many industrial processes. In this work, we investigated the capacity of SdFFF to monitor the native rice starch amylolysis. In order to determine if fractogram changes observed were correlated to granule biophysical modifications which occurred during amylolysis, SdFFF separation was associated with particle size distribution analysis. The results showed that SdFFF is an effective tool to monitor amylolysis of native rice starch. SdFFF analysis was a rapid (less than 10 min), simple and specific method to follow biophysical modifications of starch granules. These results suggested many different applications such as testing series of enzymes and starches. By using sub-population sorting, SdFFF could be also used to better understand starch hydrolysis mechanisms or starch granule structure.

SdFFF monitoring of cellular apoptosis induction by diosgenin and different inducers in the human 1547 osteosarcoma cell line

Apoptosis is one of the most important phenomena of cellular biology. Sedimentation field flow fractionation (SdFFF) has been described as an effective tool for cell separation, respecting integrity and viability. Because SdFFF takes advantage of intrinsic properties of eluted cells (size, density, shape or rigidity), we investigated the capacity of SdFFF in monitoring the early and specific biophysical modifications which occurred during cellular apoptosis induction. Then, we used, as an in vitro cellular apoptosis model, the association between human 1547 osteosarcoma cells and diosgenin, a plant steroid known to induce apoptosis. Four other molecules were studied: hecogenin, tigogenin, staurosporine and MG132. Our results demonstrated a correlation between SdFFF elution profile changes (peak shape modification and retention ratio evolution) and effective apoptosis induction. For the first time, we demonstrated that SdFFF could be used to monitor apoptosis induction as early as 6 h incubation, suggesting different applications such as screening series of molecules to evaluate their ability to induce apoptosis, or sorting apoptotic cells to study apoptosis pathway.

Mouse Embryonic Stem Cell Sorting for the Generation of Transgenic Mice by Sedimentation Field-Flow Fractionation

Mouse embryonic stem (ES) cells are an important tool for generation of transgenic mice and genetically modified mice. A rapid and efficient separation of ES cells that respects cell integrity, viability, and their developmental potential while also allowing purified ES fraction collection under sterile conditions might be of great interest to facilitate the generation of chimeric animals. In this study, we demonstrated for the first time the effectiveness of a sedimentation field-flow fractionation (SdFFF) cell sorter to provide, with a characteristic DNA content, a purified ES cell fraction and with a high in vivo developmental potential to prepare transgenic mice by generation of chimeras having a high percentage of chimerism.

Sedimentation field flow fractionation purification of immature neural cells from a human tumor neuroblastoma cell line

The use of stem cells for therapeutic applications is now an important objective for the future. Stem cell preparation is difficult and time-consuming depending on the origin of cells. Sedimentation field flow fractionation (SdFFF) is an effective tool for cell separation, respecting integrity and viability. We used the human neuroblastic SH-SY5Y clone of the SK-N-SH cell line as a source of immature neural cells. Our results demonstrated that by using SdFFF cell sorter under strictly defined conditions, and immunological cell characterization, we are now able to provide, in less than 15 min, a sterile, viable, usable and purified immature neural cell fraction without inducting cell differentiation.

Sonication effect on cellular material in sedimentation and gravitational field flow fractionation

Sonication procedures are generally used prior to field flow fractionation (FFF) separation in order to produce suspensions without aggregates. Yeast cells manufactured in active dry wine yeast (ADWY) were placed in an ultrasound water bath in order to disrupt possible clumps and to obtain a single-cell suspension to be used in optimal conditions during fermentation processes. In order to determine whether this sample preparation procedure meets absolute needs, different yeast samples before and after sonication were analysed by two field flow fractionation techniques. It is shown that 2 min of sonication in the sample preparation process is sufficient to obtain an optimal dispersion of the yeast cells, that is, without critical percentage of aggregates. To demonstrate this effect, photographs of the yeast cell suspensions were performed with non-sonicated and sonicated yeast sample dispersion. The resulting data are compared with the elution profiles obtained from the two different FFF techniques. It is demonstrated that fractogram profiles prove the effectiveness of sonication methodologies.

Deferred standards, an on-line qualification, validation and system stability probe for chromatographic assay

Specific programming of automated HPLC systems allows total on-line qualification, validation and stability monitoring using the concept of deferred standards. Setting up such a process for routine analyses in an automated HPLC system requires specific autosampler programming as well as specific monitoring software. With an autosampler, a double injection procedure is programmed, the first introducing the sample, and the second, a few minutes deferred, the deferred control standard. Two additional compounds are therefore added to the sample before and during the chromatographic process: the intemal standard for sample quantification and the deferred standard for system control. Specific methodologies are described of how to obtain classical quantitative analysis information as well as system qualification validation stability information. Experiments were performed to develop specified methodologies to monitor the quality of quantitative analysis during the life of the column by using the deferred standard concept to probe the effects of column ageing on separation characteristics.

Cortical cell elution by sedimentation field-flow fractionation

As a cell sorter, Sedimentation field-flow fractionation (SdFFF) can be defined as an effective tool for cell separation and purification, respecting integrity and viability as well as providing enhanced recovery and purified sterile fraction collection. The complex cell suspension containing both neurons and glial cells of all types, obtained from cerebral cortices of 17-day-old rat fetuses, is routinely used as a model of primary neuronal culture. Using SdFFF, this complex cell mixture was eluted in sterile fractions which were collected and cultured. SdFFF cell elution was conducted under strictly defined conditions: rapid cell elution, high recovery (negligible cell trapping), short- and long-term cell viability, sterile collection. After immunological cellular type characterization (neurons and glial cells) of cultured cells, our results demonstrated the effectiveness of SdFFF to provide, in less than 6 min, viable and enriched neurons which can be cultured for further investigations.

Sedimentation field-flow fractionation device cleaning, decontamination and sterilization procedures for cellular analysis

In Sedimentation FFF (SdFFF) practice, it is known that a large number of cell elutions create aging phenomena of the separator, thereby reducing recovery and modifying elution characteristics. Systematic cleaning procedures are developed to enhance channel lifetime, together with microbial decontamination processes. Cells can be therefore reproducibly eluted for a large number of analyses and collected under sterile conditions, if needed. This is one of the most valuable aspect if further culture or transplantation is required. Decontamination was performed using, as contaminant probe, Staphylococcus aureus, highly adherent pathogenic bacteria that eluted from SdFFF as aggregates.

Chromatographic study of terpene derivatives on porous graphitic carbon stationary phase with beta-cyclodextrin as mobile phase modifier

The stoichiometric coefficients and apparent formation constants (Kf) of alpha-terpineol, thymol, geraniol and linalool complexes with beta-cyclodextrin (beta-CD) were determined using HPLC with a porous graphitic carbon (PGC) chromatographic support. Measurements were performed with four different methanol-water mobile phases. All the terpene derivatives under study form 1:1 guest-CD complexes. Graphs of Kf as a function of the mobile phase composition appeared different from those classically described for RP-C18 and suggest that the PGC stationary phase could play an active role in the complexation process. Solute-CD inclusion and solute-stationary phase interactions may be involved in this specific behavior.

Communication as a teamwork tool in peritoneal dialysis

The growing complexity of the problems which have to be faced in providing a peritoneal dialysis service, such as giving assistance over a territory, consideration of the needs of the individual and the greater emphasis on the prevention of complications, makes multidisciplinary teamwork necessary, with the interaction of various skills. In order to succeed, teamwork requires the identification of clear objectives which are shared by all the members of the team. The various skills can best be exploited by defining roles and agreeing common aims and objectives so that the team can provide the patient with holistic treatment, which recognises the needs of the individual rather than the needs of the illness. Active cohesion between the various components is only possible through a defined communication strategy and an on-going transfer of knowledge.

Cyclooxygenase-2 up-regulation after FLAP transfection in human adenocarcinoma cell line HT29 cl.19A

Five-lipoxygenase-activating protein (FLAP) is usually described as an essential protein to activate the leukotriene (LTs) synthesis via the 5-lipoxygenase pathway. In the enterocyte model HT29 cl.19A cell line, 5-lipoxygenase metabolism was found despite the lack of FLAP expression. Therefore HT29 cl.19A represents an original mammalian model to study FLAP-dependent leukotriene synthesis. In FLAP cDNA transfected HT29 cl.19A cells, FLAP expression led to an increase in cyclooxygenase pathway products (mainly PGE2) without an increase in 5-lipoxygenase metabolism. This increase in PGE2 synthesis was associated with a cyclooxygenase-2 upregulation in comparison to untransfected HT29 cl.19A cells. These results suggest a possible interaction between the two major pathways of arachidonic acid metabolism.

Resistance to apoptosis and cyclooxygenase-2 expression in a human adenocarcinoma cell line HT29 CL.19A

BACKGROUND

COX-2 expression increases the tumorigenic potential of enterocytes. Tumorigenic effect is partially linked to an inhibition of programmed cell death which is one of the most important components in maintaining intestinal epithelium integrity.

MATERIALS AND METHODS

We analyzed apoptosis in HT29 cl.19A cells cultured over 3 weeks, in the presence (10%) or in the absence of fetal bovine serum (FBS), by analysis of genomic DNA fragmentation after agarose gel electrophoresis, morphological measurement of apoptosis using DAPI chromatin staining, and transmission electron microscopy (TEM) to identify apoptotic cellular morphological changes.

RESULTS

Regardless of the methods used, no apoptotic signs were observed for each culture condition, even if cells were cultured 3 weeks in the absence of FBS.

CONCLUSION

Using HT29 cl.19A cells (untransfected cells), we found that intrinsic or constitutive COX-2 expression in adenocarcinoma cell line was associated with spontaneous resistance to apoptosis.

Cyclooxygenase-2 expression in human adenocarcinoma cell line HT29 cl.19A

BACKGROUND

Overexpression of cyclooxygenase-2 (COX-2) has been implicated in carcinogenesis of human colorectal cancer which is one of the leading types of cancer in Western countries.

MATERIALS AND METHODS

We analyzed the COX-2 expression and activity using RT-PCR, Western blot, immunocytochemistry, RP-HPLC and EIA analysis in 0% and 10% fetal bovine serum (FBS) cultured cells.

RESULTS

HT 29 cl.19A cells exhibited a COX-2 expression called "constitutive" in the absence of FBS in culture media. This particular expression was not the result of a mutation of the HT29 cl.19A COX-2 gene promotor.

CONCLUSION

In our study, the human colon adenocarcinoma cell line, HT29 cl.19A, expressed COX-2 abnormally. This expression appeared to be at the same time inducible by the action of classical exogenous inducers such as FBS or interleukin-1 beta and "constitutive" if none of these compounds were present.

Linoleic acid peroxidation by Solanum tuberosum lipoxygenase was activated in the presence of human 5-lipoxygenase-activating protein

The present investigation describes the ability of human 5-lipoxygenase-activating protein (FLAP) to activate a plant 5-lipoxygenase. The presence of an active recombinant human FLAP in the 100000xg membrane fraction of infected Sf9 cells led to a specific increase in 9-hydroperoxyoctadecadienoic acid (9-HPOD) synthesis (+68%) or in 5-hydroperoxyeicosatetraenoic acid (5-HPETE) synthesis (+68%), after action of Solanum tuberosum tuber 5-lipoxygenase (S.t.LOX) on linoleic acid (natural plant lipoxygenase substrate) or on arachidonic acid. On the contrary, the presence of non-transfected membranes obtained from non-infected Sf9 cells led to an inhibition of lipoxygenase activity. MK-886, a potent inhibitor of leukotriene biosynthesis, blocked the FLAP dependent S.t.LOX activation after preincubation with FLAP transfected membranes. In conclusion, this study demonstrates that a recombinant human FLAP can stimulate a lipoxygenase other than mammalian 5-lipoxygenase (S.t.LOX) by using different polyunsaturated fatty acids as substrates.

Production of arachidonic acid metabolites by the colon adenocarcinoma cell line HT29 cl.19A and their effect on chloride secretion

Eicosanoids were found in large amounts in the colonic mucosa of patients suffering from inflammatory bowel diseases and colonic adenocarcinoma. The aim of this study was to evaluate the role of the intestinal epithelial cells in the arachidonic acid metabolism and their functional response to certain eicosanoids. We used the human adenocarcinoma epithelial cell line HT29 cl.19A cell, which is an in vitro model of colon carcinoma and ion transport. These cells were found to express 5- and 15-lipoxygenase, leukotriene A4 hydrolase and cyclooxygenase-1 and -2 mRNAs. We observed an arachidonic acid metabolism via 5-lipoxygenase pathway despite the lack of FLAP mRNA expression and that certain eicosanoids such as hydroperoxy- and hydroxyeicosatetraenoic acids stimulate chloride secretion.

trans,trans-2,4-decadienal: cytotoxicity and effect on glutathione level in human erythroleukemia (HEL) cells

The effects of trans,trans-2,4-decadienal (DDE), an isomer of a lipid peroxidation product were investigated on the human erythroleukemia cell line (HEL TIB 180). DDE strongly inhibits cell growth and affects cell viability without any differentiating effects. DDE treatment of HEL cells leads to a marked variation of the cellular glutathione level (GSH) and is involved in the beginning of DNA fragmentation.

Stabilization of potato tuber lipoxygenase on talc

Potato tuber lipoxygenase, like many plant enzymes is a very labile protein and can lose activity during or after the purification procedure. In order to overcome this problem, we immobilized potato tuber lipoxygenase by adsorption on talc, a silicate support. Lipoxygenase adsorption greatly increased the long-term stability of the enzyme without modifying enzyme specificity. Moreover, adsorption on talc could be used to purify labile enzymes whose enzymatic activity decreases rapidly during purification stages. A multi-step reaction to produce large quantities (around 100 mg) of fatty acid hydroperoxides without enzyme inactivation was developed.

DDT and HCH residues in indoor air arising from their use in malaria control programmes

Samples of air from rooms in a residential and rural environment, treated with either DDT or HCH at rates recommended for mosquito control under the National Malaria Eradication Programme of India, i.e. 2 and 3 g m-2, respectively, were analyzed for the residues of these insecticides. During the 8-month sampling period, DDT and HCH levels in indoor air ranged from 1.0 to 14.6 and 0.9 to 2000.1 micrograms m-3, respectively. After an initial fall, residues of DDT showed an increase again and were 5.9 micrograms m-3 in samples collected 240 days after the initial application. In contrast, HCH residues declined at a fast rate in a few days after application and remained low at the time of subsequent samplings. HCH residues were present chiefly in the vapour phase throughout the study. Thirty-four to seventy-eight percent of DDT residues were found in the particulate phase in the samples collected up to 64 days after its application and exclusively in the vapour phase at the time of later samplings. Apart from the contamination of food and feed commodities stored in premises treated for malaria control by absorption of insecticides present in the indoor atmosphere, the residues of these persistent compounds in air are also likely to result in low level pollution of the surrounding and distant environmental media by their dispersion in the global ecosystem.