Biomedical subjects

P Lemieux

Publications and source records attributed to P Lemieux.

At least 19 recordsLinked to original sources

PubMed2006

Destruction of spores on building decontamination residue in a commercial autoclave.

The U.S. Environmental Protection Agency conducted an experiment to evaluate the effectiveness of a commercial autoclave for treating simulated building decontamination residue (BDR). The BDR was intended to simulate porous materials removed from a building deliberately contaminated with biological agents such as Bacillus anthracis (anthrax) in a terrorist attack. The purpose of the tests was to assess whether the standard operating procedure for a commercial autoclave provided sufficiently robust conditions to adequately destroy bacterial spores bound to the BDR. In this study we investigated the effects of several variables related to autoclaving BDR, including time, temperature, pressure, item type, moisture content, packing density, packing orientation, autoclave bag integrity, and autoclave process sequence. The test team created simulated BDR from wallboard, ceiling tiles, carpet, and upholstered furniture, and embedded in the BDR were Geobacillus stearothermophilus biological indicator (BI) strips containing 10(6) spores and thermocouples to obtain time and temperature profile data associated with each BI strip. The results indicated that a single standard autoclave cycle did not effectively decontaminate the BDR. Autoclave cycles consisting of 120 min at 31.5 lb/in2 and 275 degrees F and 75 min at 45 lb/in2 and 292 degrees F effectively decontaminated the BDR material. Two sequential standard autoclave cycles consisting of 40 min at 31.5 lb/in2 and 275 degrees F proved to be particularly effective, probably because the second cycle's evacuation step pulled the condensed water out of the pores of the materials, allowing better steam penetration. The results also indicated that the packing density and material type of the BDR in the autoclave could have a significant impact on the effectiveness of the decontamination process.

Bacillaceae↗

PubMed2002

Inducing neutrophil recruitment in the liver of ICAM-1-deficient mice using polyethyleneimine grafted with Pluronic P123 as an organ-specific carrier for transgenic ICAM-1.

Coordinated expression of cell adhesion molecules and chemokines on the surface of vascular endothelium is responsible for the homing of immune effector cells to targeted sites. One way to attract non-activated immune cells to targeted organs is to use transgenically expressed adhesion molecules responsible for leukocyte recruitment. We have previously shown that polyethyleneimine (PEI) grafted with non-ionic amphiphilic Pluronic P123 block copolymer (P123PEI) modifies biodistribution of plasmid DNA toward the liver. In the present study, a P123PEI-formulated plasmid carrying the gene encoding for the murine ICAM-1 molecule was injected i.v. into transgenic ICAM-1-deficient mice. The RT-PCR analysis of ICAM-1 mRNA expression showed that P123PEI induced a dose-dependent expression of ICAM-1 in the liver. Furthermore, this expression of ICAM-1 induced neutrophil invasion in the liver, while no such invasion was observed in mice injected with formulated control plasmid or naked DNA. These results suggest that P123PEI allows functional transgene expression in the liver following i.v. injection and that ICAM-1 could be used to enhance immune response locally by attracting immune effector cells.

Animals↗

PubMed2002

Altered organ accumulation of oligonucleotides using polyethyleneimine grafted with poly(ethylene oxide) or pluronic as carriers.

Passive targeting provides a simple strategy based on natural properties of the carriers to deliver DNA molecules to desired compartments. Polyethylenimine (PEI) is a potent non-viral system that has been known to deliver efficiently both plasmids and oligonucleotides (ODNs) in vitro. However, in vivo systemic administration of DNA/PEI complexes has encountered significant difficulties because these complexes are toxic and have low biodistribution in target tissues. This study evaluates PEI grafted with poly(ethylene oxide) (PEO(8K)-g-PEI(2K)) and PEI grafted with non-ionic amphiphilic block copolymer, Pluronic P85 (P85-g-PEI(2K)) as carriers for systemic delivery of ODNs. Following i.v. injection an antisense ODN formulated with PEO(8K)-g-PEI(2K) accumulated mainly in kidneys, while the same ODN formulated with P85-g-PEI(2K) was found almost exclusively in the liver. Furthermore, in the case of the animals injected with the P85-g-PEI(2K)-based complexes most of the ODN was found in hepatocytes, while only a minor portion of ODN was found in the lymphocyte/monocyte populations. The results of this study suggest that formulating ODN with PEO(8K)-g-PEI(2K) and P85-g-PEI(2K) carriers allows targeting of the ODN to the liver or kidneys, respectively. The variation in the tissue distribution of ODN observed with the two carriers is probably due to the different hydrophilic-lipophilic balance of the polyether chains grafted to PEI in these molecules. Therefore, polyether-grafted PEI carriers provide a simple way to enhance ODN accumulation in a desired compartment without the need of a specific targeting moiety.

Animals↗

PubMed2001

Inflammatory gene transcription in human astrocytes exposed to hypoxia: roles of the nuclear factor-kappaB and autocrine stimulation.

Mechanisms of hypoxia-induced activation of nuclear factor-kappaB (NF-kappaB) and inflammatory genes were investigated in fetal human astrocytes in culture. Astrocytes were subjected to interleukin-1beta (IL-1beta; 50-100 u/ml; 4-24 h), or to a 4-h hypoxia (<2% O2) followed by a 4-24-h reoxygenation. NF-kappaB binding and transcriptional activity increased up to 10-fold in astrocytes exposed to IL-1beta, and up to 3-fold in astrocytes subjected to hypoxia followed by reoxygenation. Both IL-1beta- mRNAs and proteins hypoxia-induced NF-kappaB activation were blocked by the proteasome inhibitor, MG-132. MG-132 inhibited IL-1beta-induced up-regulation of IL-1beta and IL-8 mRNA and protein but increased hypoxia-stimulated expression/release of IL-1beta and IL-8. IL-1 receptor antagonist (IL-1Ra) blocked both hypoxic astrocyte-conditioned media-induced NF-kappaB activation and the expression/release of IL-1beta and IL-8. Astrocytes subjected to hypoxia in the presence of IL-1Ra failed to activate NF-kappaB, but expressed elevated levels of IL-1beta and IL-8. The data suggest that hypoxia/reoxygenation-induced up-regulation of IL-1beta and IL-8 in human astrocytes has two components, a NF-kappaB independent up-regulation during hypoxia, followed by amplification through autocrine IL-1beta-induced NF-kappaB activation during reoxygenation.

Astrocytes↗

PubMed2001

Block copolymeric biotransport carriers as versatile vehicles for drug delivery.

This review describes block copolymer-based systems that are used in drug formulation development. The use of amphiphilic block copolymers to modify pharmacological performance of various classes of drugs attracts more and more attention. This is largely attributable to the high tendency of block copolymer-based drug formulations to self-assemble, as well as flexibility of block copolymer chemistry, which allows precise tailoring of the carrier to virtually any chemical entity. Combination of these features allows adjustment of block copolymer-based drug formulations to achieve the most beneficial balance in drug biological interactions with the systems that control its circulation in and removal from the body and its therapeutic activity. The following major aspects are considered: 1) physical properties of formulations and the methods used to adjust these properties towards the highest pharmacological performance of the product; 2) combinatorial methods for optimisation of block copolymer-based formulations; 3) biological response modifying properties of block copolymer-based formulations.

Animals↗

PubMed2000

From avalanches to fluid flow: A continuous picture of grain dynamics down a heap

Surface flows are excited by steadily adding spherical glass beads to the top of a heap. To simultaneously characterize the fast single-grain dynamics and the much slower collective intermittency of the flow, we extend photon-correlation spectroscopy via fourth-order temporal correlations in the scattered light intensity. We find that microscopic grain dynamics during an avalanche are similar to those in the continuous flow just above the transition. We also find that there is a minimum jamming time, even arbitrarily close to the transition.

Journal Article↗

PubMed2000

Evaluation of polyether-polyethyleneimine graft copolymers as gene transfer agents.

Cationic copolymers consisting of polycations linked to non-ionic polymers are evaluated as non-viral gene delivery systems. These copolymers are known to produce soluble complexes with DNA, but only a few studies have characterized the transfection activity of these complexes. This work reports the synthesis and characterization of a series of cationic copolymers obtained by grafting the polyethyleneimine (PEI) with non-ionic polyethers, poly (ethylene oxide) (PEO) or Pluronic 123 (P123). The PEO-PEI conjugates differ in the molecular mass of PEI (2 kDa and 25 kDa) and the degree of modification of PEI with PEO. All of these conjugates form complexes upon mixing with plasmids, which are stable in aqueous dispersion for several days. The sizes of the particles formed in these systems vary from 70 to 200 nm depending on the composition of the complex. However, transfection activity of these systems is much lower than that of PEI (25 kDa) or Superfect as assessed in in vitro transfection experiments utilizing a luciferase reporter expression in Cos-7 cells as a model system. In contrast, conjugate of P123 with PEI (2 kDa) mixed with free P123 (9:1(wt)) forms small and stable complexes with DNA (110 nm) that exhibit high transfection activity in vitro. Furthermore, gene expression is observed in spleen, heart, lungs and liver 24 h after i.v. injection of this complex in mice. Compared to 1,2-bis(oleoyloxy)-(trimethylammonio) propane:cholesterol (DOTAP:Chol) and PEI (25 kDa) transfection systems, the P123-PEI system reveals a more uniform distribution of gene expression between these organs, allowing a significant improvement of gene expression in liver.

Animals↗

PubMed2000

A combination of poloxamers increases gene expression of plasmid DNA in skeletal muscle.

Intramuscular administration of plasmid DNA is a promising strategy to express therapeutic genes, however, it is limited by a relatively low level of gene expression. We report here that a non-ionic carrier, SP1017, composed of two amphiphilic block copolymers, pluronics L61 and F127, also known as poloxamers, significantly increases intramuscular expression of plasmid DNA. Two reporter genes, luciferase and beta-galactosidase, and one therapeutic gene, erythropoietin, were injected intramuscularly with and without SP1017 into C57Bl/6 and Balb/C mice and Sprague-Dawley rats. SP1017 increased gene expression by about 10-fold and maintained higher gene expression compared with naked DNA. Comparison of SP1017 with polyvinyl pyrrolidone (PVP) showed that SP1017 exhibited a significantly higher efficacy and its optimal dose was 500-fold lower. Experiments with beta-galactosidase using X-gal staining suggested that SP1017 considerably increased plasmid DNA diffusion through the tissue. SP1017 also improved expression of the erythropoietin gene leading to an increase in its systemic level and hematocrits. Previous toxicity studies have suggested that SP1017 has over a 1000-fold safety margin. Poloxamers used in SP1017 are listed in the US Pharmacopeia as inactive excipients and are widely used in a variety of clinical applications. We believe that the described system constitutes a simple and efficient gene transfer method to achieve local or systemic production of therapeutic proteins.

Animals↗

PubMed2000

Block and graft copolymers and NanoGel copolymer networks for DNA delivery into cell.

Self-assembling complexes from nucleic acids and synthetic polymers are evaluated for plasmid and oligonucleotide (oligo) delivery. Polycations having linear, branched, dendritic. block- or graft copolymer architectures are used in these studies. All these molecules bind to nucleic acids due to formation of cooperative systems of salt bonds between the cationic groups of the polycation and phosphate groups of the DNA. To improve solubility of the DNA/polycation complexes, cationic block and graft copolymers containing segments from polycations and non-ionic soluble polymers, for example, poly(ethylene oxide) (PEO) were developed. Binding of these copolymers with short DNA chains, such as oligos, results in formation of species containing hydrophobic sites from neutralized DNA polycation complex and hydrophilic sites from PEO. These species spontaneously associate into polyion complex micelles with a hydrophobic core from neutralized polyions and a hydrophilic shell from PEO. Such complexes are very small (10-40 nm) and stable in solution despite complete neutralization of charge. They reveal significant activity with oligos in vitro and in vivo. Binding of cationic copolymers to plasmid DNA forms larger (70-200 nm) complexes. which are practically inactive in cell transfection studies. It is likely that PEO prevents binding of these complexes with the cell membranes ("stealth effect"). However attaching specific ligands to the PEO-corona can produce complexes, which are both stable in solution and bind to target cells. The most efficient complexes were obtained when PEO in the cationic copolymer was replaced with membrane-active PEO-b-poly(propylene oxide)-b-PEO molecules (Pluronic 123). Such complexes exhibited elevated levels of transgene expression in liver following systemic administration in mice. To increase stability of the complexes, NanoGel carriers were developed that represent small hydrogel particles synthesized by cross-linking of PEI with double end activated PEO using an emulsification/solvent evaporation technique. Oligos are immobilized by mixing with NanoGel suspension, which results in the formation of small particles (80 nm). Oligos incorporated in NanoGel are able to reach targets within the cell and suppress gene expression in a sequence-specific fashion. Further. loaded NanoGel particles cross-polarized monolayers of intestinal cells (Caco-2) suggesting potential usefulness of these systems for oral administration of oligos. In conclusion the approaches using polycations for gene delivery for the design of gene transfer complexes that exhibit a very broad range of physicochemical and biological properties, which is essential for design of a new generation of more effective non-viral gene delivery systems.

Cations↗

PubMed1999

Hsp27 overexpression inhibits doxorubicin-induced apoptosis in human breast cancer cells.

Previously we demonstrated that heat shock protein 27 (hsp27) overexpression confers resistance to the chemotherapeutic agent doxorubicin in MDA-MB-231 breast cancer cells. Since induction of apoptosis is one underlying mechanism of chemotherapeutic drug action, we investigated the effect of hsp27 overexpression on doxorubicin-induced apoptosis, finding that hsp27 protects MDA-MB-231 cells from apoptosis. We also examined expression of the doxorubicin target, topoisomerase II (topo II), in control and hsp27-overexpressing stable transfectants, as topo II expression is important for both drug sensitivity and the initiation of apoptosis by doxorubicin. The relative levels of both topo IIalpha and beta were higher in the controls than the hsp27-overexpressing clones, suggesting that the apoptotic protective effect of hsp27 overexpression in MDA-MB-231 cells is associated with altered topo II expression.

Antigens, Neoplasm↗

PubMed1999

Low cell motility induced by hsp27 overexpression decreases osteolytic bone metastases of human breast cancer cells in vivo.

The mechanisms controlling the formation of osteolytic bone metastases in patients with breast cancer are still poorly understood. To explore the role of motility in the establishment of osteolytic bone metastases, we have used a model of bone metastasis in which MDA-MB-231 breast cancer cells exhibiting low (hsp27-transfectants) and high (control-transfectant) endogenous cell motility were compared. We found that MDA-MB-231 cells exhibiting low cell motility were less capable of establishing osteolytic lesions. The number and the area of the osteolytic lesions in mice inoculated with low motility cells were both significantly smaller. Histomorphometry of bone lesions also demonstrated less tumor area in mice bearing hsp27 transfectants although there was no difference in the osteoclast number per square millimeter of tumor-bone interface. These data suggest that cell motility may be an important mechanism in the metastatic cascade of breast cancer cells to the bone and that controlling cell motility may be a useful target to prevent the establishment of osteolytic bone metastases.

Animals↗

PubMed1997

Quercetin inhibits heat shock protein induction but not heat shock factor DNA-binding in human breast carcinoma cells.

The flavonoid quercetin inhibits the heat-induced synthesis of heat shock proteins (hsps) in a variety of cell lines. To determine whether quercetin could inhibit hsp expression in breast cancer cells, we used the human breast cancer cell line, MDA-MB-231. Treatment of these cells with quercetin decreased the heat-induced synthesis of hsp27 and hsp70. However, inhibition of hsp expression did not correspond with the reduced ability of heat shock transcription factors (HSFs) to bind DNA. Furthermore, while quercetin treatment inhibited HSF2 expression, it only slightly affected HSF1 expression in breast cancer cells. In contrast, quercetin inhibited both HSF DNA-binding activity and HSF expression in HeLa cells. Our studies suggest that quercetin's action is cell-type specific, and in breast cancer cells may involve regulation of HSF transcriptional activity, rather than regulation of its DNA-binding activity.

Binding Sites↗

PubMed1997

The small heat shock protein hsp27 increases invasiveness but decreases motility of breast cancer cells.

The small heat shock protein hsp27 is often expressed at high levels in clinical breast tumors; however, its biological role in this disease still remains unclear. Several laboratories have recently shown that hsp27 expression is associated with aggressive tumor behavior. We hypothesized that hsp27 may influence the metastatic tumor process since this is part of tumor 'aggressiveness'. Therefore, we stably transfected breast cancer cell lines with sense (MDA-MB-231) and antisense (MDA-MB-435) hsp27 constructs, respectively, and examined various cellular aspects associated with the metastatic process. We found that hsp27-overexpressing clones lost their protrusive morphology, but exhibited higher membrane ruffling as compared to low expressing cells. hsp27 overexpression also resulted in decreased cell motility, but invasiveness, adhesion, and growth in Matrigel were all significantly increased. Conversely, antisense suppression of hsp27 expression resulted in increased cell motility, but decreased in vitro invasiveness. The direct correlation of hsp27 levels with metastasis was confirmed by an in vivo assay measuring the number of lung metastases in mice injected with hsp27-transfected cells. Thus, we conclude that hsp27 overexpression may influence the invasive and metastatic potential of human breast cancer cells.

Animals↗

PubMed1996

The role of the estrogen receptor in tumor progression.

We will discuss two estrogen receptor (ER) variants that may play a role in breast cancer initiation or progression. One is a truncated receptor, which has been named the exon 5 ER deletion variant, and the other is called a hyper-sensitive variant of the ER that is sensitive to low levels of hormone. Both ER variants differ from the wild-type ER in their hormone binding domains (HBD). The exon 5 ER deletion variant lacks a large portion of the HBD, while the hyper-sensitive ER variant has a point mutation in a conserved region of the HBD. The exon 5 ER deletion variant is transcriptionally active in the absence of hormone, and is thus considered constitutively-active. In contrast, the hyper-sensitive ER variant is functionally active in response to subphysiological concentrations of estrogen. We speculate that both ER variants may form productive heterodimers with wild-type receptor to modify the normal function of ER in the breast.

Animals↗

PubMed1994

Teaching cancer chemotherapy by means of a computer simulation.

BIO-1014 is an educational computer-based program written in TURBO PASCAL 3.01 which simulates experiments of antitumour activity. Basically, this program offers the user the possibility of checking the therapeutical efficiency of anticancer drugs as applied to different tumors, but many other types of experiment can be also performed with BIO-1014. Drugs such as methotrexate, cyclophosphamide and arabinosylcytosine can be tested on the following tumors: sarcoma, carcinoma, leukemia and melanoma. The dose, the number of treatments per day, the total number of treatments and the time interval between the treatments are the parameters to be adjusted for each therapeutical schedule. Tumoral growth, cause of death and survival are among the results that are generated after each simulation. These results are either tabulated or plotted. In addition, four statistical tests have also been integrated to the program in order to provide with a way to check whether or not there is a significant difference in terms of survival between two groups of mice differently treated. Furthermore, the program has been elaborated to also consider some physiological phenomena met within an anticancer drug screening programme. The potential and the performance of the program BIO-1014 is presented and discussed.

Animals↗

PubMed1988

Optimization of the tetrazolium-based colorimetric assay for the measurement of cell number and cytotoxicity.

We report some modifications of the semiautomated tetrazolium-based assay for the measurement of anchorage-dependent and -independent mammalian cells. The various factors affecting color production, such as the concentration of tetrazolium, incubation period, the type and volume of solvent, were optimized. Using KCN and daunorubicin as cytotoxic agents, the influence of dead cells was studied on the measurement. The assay was tested with mouse leukemia P388 cells, H69 small cell carcinoma cells growing in suspension and anchorage dependent colon adenocarcinoma cells (LoVo). Centrifugation of the microtitration plate was eliminated by the use of a Skatron supernatant collection system. Although the use of the MTT assay is rapid and precise, we found that care should be taken when using this assay for short-term cytotoxicity assays since non-viable cells also reduce the tetrazolium.

Animals↗

PubMedDate not supplied

In vivo cytotoxicity and antineoplastic activity of a transferrin-daunorubicin conjugate.

Transferrin, the major iron-binding protein in the plasma of vertebrate species, is an essential growth factor for proliferating malignant cells. The specific receptor binds diferric transferrin and is endocytosed into the cell. We would like to take advantage of this physiologic phenomenon using an active transferrin-daunorubicin conjugate to target cancer cells. We have compared the in vitro and the in vivo activity of free daunorubicin and of daunorubicin transferrin conjugate on cancer cells. The results suggest that our conjugate is less toxic and more active upon malignant cells than the free drug, daunorubicin, while being less toxic for normal cells.

Animals↗

PubMedDate not supplied

[Artificial paradise].

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Lysergic Acid Diethylamide↗