Biomedical subjects

C Huard

Publications and source records attributed to C Huard.

16 recordsLinked to original sources

PubMed2003

Genotyping of Staphylococcus aureus isolated from various sites on farms with dairy sheep using pulsed-field gel electrophoresis.

We investigated the genetic diversity of 179 Staphylococcus aureus isolates recovered from various sites in 10 farms producing cheeses manufactured with raw ewe's milk. Isolates were collected from handcrafted cheeses, bulk tank milk, milk from half-udders, skin abscesses on the udder if present, hands and anterior nares of farmers, and air of the milking area. The isolates were typed using pulsed-field gel electrophoresis (PFGE) of DNA SmaI digests and compared to other isolates of S. aureus isolated in different hosts or in different locations. The results showed that nine farms were contaminated by S. aureus isolates with identical banding patterns (named OV) or by genetically related isolates (named OV'). These dominant banding patterns were found in a variable proportion of the samples from each farm (range: 11-100%). Most of the strains isolated from nasal carriage or strains isolated from other regions or from other animal species had different PFGE patterns to OV or OV', except for three strains. These results show that a single clone of S. aureus is widely distributed both in infected mammary glands and in cheese produced from raw milk. This study confirms that infected mammary glands are the main source of the contamination of dairy products in sheep.

Animals↗

PubMed2001

Growth factor-specific signaling pathway stimulation and gene expression mediated by ErbB receptors.

The mechanisms by which receptor tyrosine kinases (RTKs) utilize intracellular signaling pathways to direct gene expression and cellular response remain unclear. A current question is whether different RTKs within a single cell target similar or different sets of genes. In this study we have used the ErbB receptor network to explore the relationship between RTK activation and gene expression. We profiled growth factor-stimulated signaling pathway usage and broad gene expression patterns in two human mammary tumor cell lines expressing different complements of ErbB receptors. Although the growth factors epidermal growth factor (EGF) and neuregulin (NRG) 1 similarly stimulated Erk1/2 in MDA-MB-361 cells, EGF acting through an EGF receptor/ErbB2 heterodimer preferentially stimulated protein kinase C, and NRG1beta acting through an ErbB2/ErbB3 heterodimer preferentially stimulated Akt. The two growth factors regulated partially overlapping yet distinct sets of genes in these cells. In MDA-MB-453 cells, NRG1beta acting through an ErbB2/ErbB3 heterodimer stimulated prolonged signaling of all pathways examined relative to NRG2beta acting through the same heterodimeric receptor species. Surprisingly, NRG1beta and NRG2beta also regulated partially overlapping but distinct sets of genes in these cells. These results demonstrate that the activation of different RTKs, or activation of the same RTKs with different ligands, can lead to distinct profiles of gene regulation within a single cell type. Our observations also suggest that the identity and kinetics of signaling pathway usage by RTKs may play a role in the selection of regulated genes.

Animals↗

PubMed2000

Effects of four inorganic lead compounds on the proliferation and junctional coupling of cultured REL liver cells.

BACKGROUND: Chronic, low-level exposure to inorganic lead (Pb) has been involved in a number of human diseases, including tumors. In this study, the effect of four different inorganic Pb compounds (acetate, chloride, monoxide, and sulfate) was evaluated, in vitro, on liver-derived REL cells, known to be very sensitive to tumor promoters. METHODS: Cytotoxicity and effects on intercellular communication (GJIC) were evaluated, respectively, by cell- density/proliferation and dye-transfer assays. Pb concentration in the media solutions used for each treatment was quantified by atomic absorption spectroscopy-electrothermal atomization. RESULTS: Each of the Pb compounds we tested showed a typical dose- and time-related effect on REL cell proliferation, this effect not being related to the free metal concentration. Contrary to classical tumor promoters, none of the compounds significantly affected REL GJIC (1-hour treatment). CONCLUSIONS: Our results are indicative of specificity in the effects of the different Pb compounds. The mechanism(s) of their action need further investigations.

Animals↗

PubMed2000

Bilateral tension pneumothorax during jet ventilation: a case report.

Jet ventilation (JV) involves high-pressure ventilation for upper laryngeal laser procedures. Anesthetic management for the patient undergoing JV can be challenging, as complications of JV can include subcutaneous emphysema and tension pneumothorax. A 52-year-old woman with a diagnosis of vocal cord polyps presented for direct microlaryngoscopy and laser laryngoplasty with JV. Intraoperatively, the patient developed lack of bilateral chest movement and an audible change in jet-ventilatory sounds. The patient was reintubated with a standard endotracheal tube. Subsequent attempts to ventilate the patient failed. A diagnosis of bilateral tension pneumothorax was made. Immediate pleural decompression resulted in improved ventilatory and hemodynamic status. The purpose of this case report is to discuss the pathophysiology related to tension pneumothorax and anesthetic implications for management of cases involving JV.

Female↗

PubMed1999

Molecular classification of cancer: class discovery and class prediction by gene expression monitoring.

Although cancer classification has improved over the past 30 years, there has been no general approach for identifying new cancer classes (class discovery) or for assigning tumors to known classes (class prediction). Here, a generic approach to cancer classification based on gene expression monitoring by DNA microarrays is described and applied to human acute leukemias as a test case. A class discovery procedure automatically discovered the distinction between acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) without previous knowledge of these classes. An automatically derived class predictor was able to determine the class of new leukemia cases. The results demonstrate the feasibility of cancer classification based solely on gene expression monitoring and suggest a general strategy for discovering and predicting cancer classes for other types of cancer, independent of previous biological knowledge.

Acute Disease↗

PubMed1998

Transplantation of dermal fibroblasts expressing MyoD1 in mouse muscles.

Transplantation of normal myoblasts into dystrophic muscles is a potential treatment for Duchenne muscular dystrophy (DMD). However, the success of such grafts is limited by the immune system responses. To avoid rejection problems, autologous transplantation of the patient's corrected myoblasts has been proposed. Regretfully, the low proliferative capacity of DMD myoblasts in culture (due to their premature senescence) limits such procedure. On the other hand, modification of dermal fibroblasts leading to the myogenic pathway using a master regulatory gene for myogenesis is an interesting alternative approach. In this study, the retrovirally encoded MyoD1 cDNA was introduced in dermal fibroblasts of TnI LacZ mice to provoke their conversion into myoblast-like cells. In vitro and in vivo assays were done and the results were compared to those obtained with uninfected fibroblasts and myoblasts. Some MyoD1-expressing fibroblasts were able to fuse and to express beta-galactosidase (under the transcriptional control of the Troponin I promoter), dystrophin and desmin in vitro. Thirty days following implantation of these modified fibroblasts in muscles of mdx mice, an average of 7 beta-Gal+/Dys-muscle fibers were observed. No beta-Gal+ fibers were observed after the transplantation of uninfected fibroblasts. Our results indicate that the successful implantation of myoblasts obtained from genetically modified fibroblasts is indeed feasible. However, the in vitro conversion rate and the in vivo fusion of genetically modified fibroblasts must be largely increased to consider this approach as a potential therapy for DMD and other myopathies.

Animals↗

PubMed1998

Anti-inflammatory effect of transforming growth factor-beta1 in myoblast transplantation.

BACKGROUND: The inflammatory reaction that occurs during the 5 days after transplantation led at 3 days to the death of 70% of injected myoblasts. Use of anti-inflammatory agents appeared to be a possible way to increase myoblast survival. The application of gene transfer techniques to cell transplantation offers the potential for the prevention of inflammatory reaction. METHODS: In this study, transforming growth factor-beta1 (TGF-beta1) gene was introduced in myoblasts with a retroviral vector to permit the secretion of this anti-inflammatory cytokine. Survival of (1) infected myoblasts expressing TGF-beta1 or (2) normal myoblasts transplanted with genetically modified cloned myoblasts was compared with survival of normal myoblasts. RESULTS: Expression of TGF-beta1 by myoblasts or by cotransplanted cells decreased myoblast mortality after 3 days by roughly 20% (66.0+/-3.0% in control vs. 46.3+/-4.2% and 46.2+/-5.9%). The increase of myoblast survival by TGF-beta1 expression was correlated with a lower polymorphonuclear cell and macrophage infiltration in muscles compared with control. In addition, cytotoxicity of neutrophils against myoblasts was assayed in vitro. The oxidation of myoblasts by activated neutrophils was decreased after infection of the myoblasts with the TGF-beta1 retroviral vector. CONCLUSIONS: These data demonstrate that the insertion of TGF-beta1 decreases inflammatory reaction observed after myoblast transplantation and thus prolongs their survival.

Animals↗

PubMed1997

Prevention by anti-LFA-1 of acute myoblast death following transplantation.

Myoblast transplantation is a potential treatment for Duchenne muscular dystrophy. One of the problems possibly responsible for the limited success of clinical trials is the rapid death of the myoblasts after transplantation. To investigate this problem, myoblasts expressing beta-galactosidase were injected in the tibialis anterior muscles of mice. Beta-galactosidase activity was reduced by 74.7% after 3 days. Myoblast death observed at 3 days was reduced to 57.2% when the hosts were irradiated. This result suggested that host cells were contributing to this phenomenon. Transplantation in SCID and FK506-treated mice did not reduce cell death, indicating that mortality was not due to an acute specific reaction. In contrast, administration of the anti-LFA-1 (TIB-213) mAb markedly reduced myoblast death at 3 days without altering leukocyte tissue infiltration. We postulated that neutrophils were mediating myoblast mortality by an LFA-1-dependent mechanism. To test this hypothesis, IL-1beta-activated myoblasts were loaded with 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate, di(acetoxymethylester) (DCFH), a marker for oxidative stress. Addition of neutrophils and zymosan-activated serum resulted in a time-dependent DCFH fluorescence; this neutrophil-induced oxidation was considerably inhibited by TIB-213. These results indicate that an effective control of the inflammatory reaction will be necessary for any new clinical trials of myoblast transplantation and suggest that neutrophil-mediated myoblast injury occurs by an LFA-1-dependent pathway.

Animals↗

PubMed1997

Inflammatory damage following first-generation replication-defective adenovirus controlled by anti-LFA-1.

First-generation replication-defective adenoviruses have been reported to lead to transient reporter gene expression due to a specific immune reaction involving T and B lymphocytes. Some recent reports have also demonstrated the presence of a nonspecific inflammatory reaction involving macrophages and neutrophils after both intramuscular injections and viral vectors transduction. To further investigate this nonspecific inflammatory reaction, deltaE1/E3a adenoviruses were injected intramuscularly in immunocompetent mice. Some of these mice were treated with anti-LFA-1. The adenovirus-injected muscles showed abundant CD4+, CD8+, LFA-1+, and Mac-1+ cell infiltration 3 days after the deltaE1/E3a injection. The anti-LFA-1 monoclonal antibody was able to block the nonspecific inflammatory damage due mostly to neutrophils and macrophages. The anti-LFA-1 did not produce this effect by reducing the muscle infiltration by LFA-1+ cells. It may instead have blocked the direct interaction between LFA-1 and ICAM-1 thus preventing the damage produced by the respiratory burst of neutrophils. Blocking the resulting damage of this inflammatory reaction with anti-LFA-1 in animals also treated with FK506, a powerful immunosuppressant for gene therapy, largely increased the long-term transgene expression compared with mice only treated with FK506.

Adenoviridae↗

PubMed1996

Specific in vivo binding in the rat brain of [18F]RP 62203: a selective 5-HT2A receptor radioligand for positron emission tomography.

In vivo pharmacokinetic and brain binding characteristics of [18F]RP 62203, a selective high-affinity serotonergic 5-HT2A receptor antagonist, were assessed in the rat following intravenous injection of trace amount of the radioligand. The radioactive distribution profile observed in the brain 60 min after injection was characterized by greater than fourfold higher uptake in neocortex as compared to cerebellum (0.38 +/- 0.07% injected dose/g, % ID/g and 0.08 +/- 0.01 ID/g, respectively), consistent with in vivo specific binding to the 5-HT2A receptor. Furthermore, specific [18F]RP 62203 binding significantly correlated with the reported in vitro distribution of 5-HT2A receptors, but not with known concentration profiles of dopaminergic D2 or adrenergic alpha 1 receptors. Finally, detectable specific binding was abolished by pretreatment with large doses of ritanserin, a selective 5-HT2A antagonist, which resulted in uniform uptakes across cortical, striatal and cerebellar tissues. Thus, [18F]RP 62203 appears to be a promising selective tool to visualize and quantify 5-HT2A brain receptors in vivo with positron emission tomography.

Adrenergic beta-Antagonists↗

PubMed1985