Biomedical subjects

Julien Mazières

Publications and source records attributed to Julien Mazières.

5 recordsLinked to original sources

PubMed2004

Geranylgeranylated, but not farnesylated, RhoB suppresses Ras transformation of NIH-3T3 cells.

RhoB is a low molecular weight GTPase that is both farnesylated (RhoB-F) and geranylgeranylated (RhoB-GG) in cells. Based on data from rodent cell models, it has been suggested that RhoB displays differential effects on cell transformation, according to the nature of its prenylation. To test directly this hypothesis, we generated GTPase-deficient RhoB mutants that are exclusively either farnesylated or geranylgeranylated. We show that in Ras-transformed murine NIH-3T3 cells, RhoB-F enhances, whereas RhoB-GG and RhoB (F/GG) suppresses anchorage-dependent and -independent cell growth as well as tumor growth in nude mice. We then demonstrate that Ras constitutive activation of the tumor survival pathways Akt and NF-kappa B are blocked by RhoB-GG, but not by RhoB-F, providing further support for the opposing role of RhoB-F and RhoB-GG in Ras malignant transformation in NIH-3T3 cells. In addition, both RhoB (F/GG) and RhoB-GG induce apoptosis in Ras-transformed NIH-3T3 cells whereas RhoB-F has no effect. Our data demonstrate that RhoB-F and RhoB-GG which differ only by a 5-carbon isoprene behave differently in rodent cells highlighting the important role of prenyl groups in protein function and emphasize the potency of RhoB to regulate negatively the oncogenic signal.

Animals↗

PubMed2003

[Treatment and prevention of pneumococcal pneumonia].

Streptococcus pneumoniae is the most commonly identified pathogen in patients with community-acquired pneumonia. 40% of isolated strains in France are of decreased sensibility to penicillin, two third being multiresistant to antibiotics. However, high doses of some beta-lactams are effective in vivo against the majority of circulating strains (MIC > 2 mg/L). For this reason according to French guidelines amoxicillin (3 g/day) is the first line recommended treatment. Telithromycin is an alternative, or ceftriaxone (1 g/day) in more severe cases. If the level of resistance increases (MIC > 4 mg/L) guidelines would be revisited. Effectiveness of pneumococcal vaccination has been confirmed in cases of bacteriemic pneumococcal pneumonia (elderly patients included). Vaccine is recommended among persons with comorbiditie(s) and 65 years old population.

Anti-Bacterial Agents↗

PubMed2003

Limited operation for severe multisegmental bilateral bronchiectasis.

BACKGROUND: Some patients exhibiting severe multisegmental bilateral bronchiectasis are no longer improved with antibiotic treatment and drainage and, most of the time, operation is contraindicated. In our institution, limited operation has been offered to select patients for this indication. We report our data regarding the feasibility and utility of such a procedure. METHODS: We studied 16 patients who underwent surgical removal of nonlocalized disease between 1990 and 1999. We report the mortality and morbidity rates of this surgical procedure and the clinical, bacteriological, and functional data for each patient. RESULTS: There was no mortality and the morbidity was low (18%, all with favorable outcome). Symptoms such as hemoptysis, sputum production, or dyspnea were also improved. The recurring infections decreased in frequency in 8 patients and disappeared completely in 5 others. The bacteriological data assessment revealed disappearance of germs in 4 patients and persistence of chronic colonization in others. Postoperative spirometric data were not worsened and postoperative computed tomographic scans did not show progression of lesions not removed. CONCLUSIONS: These results suggest that, in properly selected patients, lasting symptomatic improvement can be achieved by resection. Limited operation may be indicated in nonlocalized bilateral bronchiectasis, provided that a target can be identified. This procedure is supported by physiopathologic arguments and is particularly relevant to patients with bronchiectasis with cystic and functionless territories.

Adolescent↗

PubMed2003

[Farnesyl transferase inhibitors: one target may be found in another].

The fact that proteins such as Ras require farnesylation to induce malignant transformation prompted many investigators to design farnesyl transferase inhibitors (FTI) as novel anticancer drugs. FTIs inhibit the growth of ras transformed cells in vitro and induce tumor regression in ras dependent tumor in vivo. Moreover, FTIs inhibit tumor progression in human tumor xenograft models. Currently, FTIs are undergoing phase I and II trials in various cancer types. They show impressive antitumour efficacy and they lack toxicity. Despite these promising results, the development of such molecules in hindered by the absence of appropriate clinical endpoints and of surrogate biological markers. Indeed, it seems likely that Ras is not the critical target of FTIs and that inhibition of the farnesylation of proteins such as RhoB, might also contribute to the observed antitumour properties. Identification of targets that underlie their biological effect is essential in order to predict and evaluate their efficacy.

Alkyl and Aryl Transferases↗

PubMed2002

Large cell neuroendocrine carcinoma of the lung: pathological study and clinical outcome of 18 resected cases.

Large cell neuroendocrine carcinoma of the lung (LCNEC) has been recently redefined by the World Health Organisation (WHO) classification but the appropriate treatment remains unclear. We reviewed 18 consecutive resected cases of LCNEC. Two pathologists assessed diagnosis by applying rigorously the last WHO criteria. We reported the pathological features and the clinical outcome of this particular tumour. All patients were men with a median age of 63 years. Clinicopathologic stages corresponded to stage I (n = 8), II (n = 8) and IIIA (n = 2). All patients were treated as non-small cell lung carcinoma (NSCLC) and underwent surgery without any adjuvant treatment except four post-operative radiotherapy for N2 or T3 disease. The evolution was pejorative for 14 patients: one patient died of post-operative complications and 13 patients relapsed with distant metastases that occurred in 10 cases within 6 months after surgery. One-year survival rate was 27% and survival rate at the end of follow-up was 22%, which were both less than expected for stage-comparable NSCLC. Survival was neither influenced by lymph node status nor by pathological or molecular findings. Among the 10 evaluable patients with metastatic disease that received palliative platin-etoposide chemotherapy only two had partial tumour regressions (20%). Our study suggests that applying to LCNEC the NSCLC standard treatment lead to poor prognosis even in localised disease with a high incidence of early metastatic spread and a low response rate to chemotherapy. This way of relapse underlies the necessity of an efficient chemotherapy in order to improve survival.

Antineoplastic Combined Chemotherapy Protocols↗