Biomedical subjects

G Lefebvre

Publications and source records attributed to G Lefebvre.

At least 19 recordsLinked to original sources

PubMed2006

Remote sensing based identification of environmental risk factors associated with West Nile disease in horses in Camargue, France.

Geographic information system and remote sensing technologies were used to identify landscape features associated with risk of West Nile virus transmission as defined by the presence of confirmed horse cases. SPOT-4 images of Camargue area were used to generate a map of landscape categories of epidemic foci and the geographic information system was employed to determine the proportion of landscape components surrounding 10 horse case sites and 17 control sites. The spatio-temporal analysis of the cases outbreak gave the best results for a spatial window of 9 km and a temporal window of 18 days. Two clusters were identified (relative risk=3.35), both in the wet area of Camargue, near the town "Les Saintes Maries de la Mer". The first one was 4 km radius, the second 9 km. The relationships between the presence of cases and proportions of landscape categories were analyzed using generalized linear model. The best model indicated that rice fields and dry bushes, wet "sansouire" and open water were the major components of the landscape that were associated with the presence of West Nile virus cases.

Animals↗

PubMed2005

The second trimester Doppler ultrasound examination is the best predictor of late pregnancy outcome in systemic lupus erythematosus and/or the antiphospholipid syndrome.

OBJECTIVE: To examine the predictive value of clinical examination, laboratory tests and Doppler ultrasound examination in systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS) pregnancies. METHODS: A prospective study of 116 pregnancies followed in a single tertiary referral centre. Outcomes analysed were fetal/neonatal death and adverse pregnancy outcome. Univariate analysis was performed for: (i) medical and obstetric history; (ii) medical and obstetric clinical examination; (iii) biological data; (iv) Doppler ultrasound examination. Variables significantly associated with the outcomes in the univariate analysis were entered into a logistic regression model. RESULTS: Sixteen out of 116 pregnancies ended in 12 fetal deaths and 4 embryonic losses. Hence, data for 100 pregnancies were analysed. Seven fetal deaths and one neonatal death occurred, associated with abnormal end-diastolic umbilical artery Doppler flow at the second trimester (P < 0.006), a history of thrombophlebitis (P < 0.001) or notched uterine artery and growth restriction at the second trimester (P < 0.002). Multivariate analysis retained abnormal end-diastolic umbilical artery Doppler flow (P = 0.047) and history of thrombophlebitis (P = 0.018) as significant predictors. Thirty-one adverse pregnancy outcomes occurred, associated with notched uterine artery (P < 0.00003), abnormal end-diastolic umbilical artery Doppler flow (P < 0.0006) and fetal growth restriction at the second trimester (P < 0.008), growth restriction (P < 0.00001) and notched uterine artery at the third trimester (P < 0.0008), use of heparin (P < 0.05) and history of thrombophlebitis (P < 0.04). Notched uterine artery at the second trimester remained the only predictor in multivariate analysis (P = 0.001). CONCLUSIONS: Results of the second trimester Doppler ultrasound examination are the best predictors for late pregnancy outcome in SLE and/or APS.

Antiphospholipid Syndrome↗

PubMed2005

[Prenatal ultrasound diagnosis of neuroblastoma].

With the progress of foetal ultrasonography, diagnosis of foetal tumors can be made before birth. We report five cases of prenatally detected neuroblastoma of the adrenal glands. Diagnosis was made during the third trimester in all cases. At birth no clinical sign related to the tumor was present, and urinary catecholamines were within normal ranges. On ultrasound scans the tumor was cystic in 1 case, solid in 2 cases and of mixed echogenicity in 2 cases. All children were operated on without pre or postoperative chemotherapy. In each setting the tumor was a stage I neuroblastoma according to the Evans classification. All children are alive and disease-free with a follow-up of 32 months at 14 years.

Adrenal Gland Neoplasms↗

PubMed2004

Anaerobic biodegradation of an organic by-products leachate by interaction with different mine tailings.

Deinking by-products from paper recycling have been used as cover materials on acid-producing tailings. Due to residual cellulose, anaerobic degradation leads to the production of an organic-rich leachate, which may percolate through the tailings. This study aims at describing the influence of the tailings' characteristics on the attenuation of organic matter in leachate and at discussing the degradation mechanisms. To this end, leachate was mixed with different types of tailings, including three unoxidized tailings with varying acid generation potentials and one tailing in three states of oxidation. Regularly, selected biochemical parameters were analyzed to access the evolution of organic components. The results show that when leachate from deinking by-products was placed in contact with tailings, phase and acid-base balance reactions took place in the beginning. Subsequently, oxidation-reduction reactions dominated the chemistry of the system. The type, the constituents, and the state of oxidation of the mine tailings condition the mechanisms of biodegradation of organic components. Methanogenesis was predominant in the control sample (pure organic leachate) but was absent in all leachate-tailings mixtures. No biodegradation was observed in the liquid phase for oxidized tailings and the organic concentration remained constant for unoxidized tailings, independently of the acid-generation potential. The biodegradation efficiency was optimal when the leachate was in contact with a mixture of oxidized and unoxidized tailings due to sulfate-reduction.

Acids↗

PubMed2003

[Oocytes in vitro maturation: results and future in humans].

Mature oocytes are rare and highly specialized cells. In vitro maturation of human oocytes is an emerging assisted reproductive technology allowing to produce more mature oocytes without ovarian stimulation. Whereas in vitro maturation is technically more demanding than conventional in vitro fertilization for the laboratory, it carries many potential advantages, for example, in terms of lower treatment heaviness and removal of risk of severe ovarian hyperstimulation syndrome for the patients. Although the technology is still experimental, oocytes in vitro maturation has been successfully used and pregnancies and live births have been reported. Despite these successes, the overall efficiency of in vitro maturation remains low and this procedure must still be improved. The different steps of in vitro maturation process are shown and discussed as well as results in terms of pregnancy and live birth rates.

Cell Culture Techniques↗

PubMed2001

Mode of action, purification and amino acid sequence of plantaricin C19, an anti-Listeria bacteriocin produced by Lactobacillus plantarum C19.

Plantaricin C19, an anti-Listeria bacteriocin, was successfully purified by adsorption to and release from producing cells at low pH combined with reverse phase high-performance liquid chromatography (HPLC). The purification resulted in a 900-fold increase in specific activity with a yield of 15% of the original activity. Mass spectrometry analysis gave a molecular weight of 3845.3. Protein microsequencing identified 36 amino acids. Plantaricin C19 is rich in both hydrophobic and basic amino acids in good accordance with its basic and hydrophobic character. Comparison of the amino acid sequence of plantaricin C19, with the sequence of some other anti-Listeria bacteriocins produced with lactic acid bacteria, revealed that plantaricin C19 has in its N-terminal region the consensus sequence--YYGNGL--(uniquely with Valine instead of Leucine as found in all other bacteriocins), identifying plantaricin C19 as a pediocin-like bacteriocin. Plantaricin C19 exerted a bacteriostatic action on sensitive cells of Listeria grayi IP 6818 in BHI broth. No loss of intracellular K+, Mg2+ or UV-absorbing materials was observed. Adsorption of plantaricin C19 on L. grayi CIP 6818 decreased in the presence of salts.

Amino Acid Sequence↗

PubMed2001

Pregnancy in past or present lupus nephritis: a study of 32 pregnancies from a single centre.

OBJECTIVE: To study maternal and fetal outcome in women with past or present histologically proven systemic lupus erythematosus (SLE) nephritis. METHOD: Retrospective study of 32 pregnancies in 22 women with past or present histologically proven SLE nephritis in a single French centre. RESULTS: Pregnancy (25 planned and 7 not planned) occurred in a mean (SD) of 8 (5) years after SLE diagnosis and 6 (4) years after renal disease onset. Seven occurred in women with antiphospholipid syndrome. At pregnancy onset, all but one woman had creatininaemia below 100 micromol/l, five had proteinuria >0.5 g/day, none had hypertension. Twelve pregnancies occurred in women previously treated with immunosuppressant drugs. Treatment comprised prednisone (n=31), hydroxychloroquine (n=11), aspirin (n=22), heparin (n=12), and azathioprine in one patient with steroid resistant nephrotic syndrome disclosing SLE. No therapeutic abortion was done. During pregnancy or the postpartum period, or both, proteinuria >0.5 g/day occurred in 10 women (five related to pre-eclampsia, four to renal flare, one to stable nephrotic syndrome). One flare consisted of mild arthralgias. Pregnancy outcome comprised one feto-maternal death in SLE disclosed by pregnancy, five embryonic losses, two fetal deaths, and 18 premature (one neonatal death) and six full term births. No criterion appeared to influence fetal survival significantly. At long term, one patient died during an SLE flare, three women had renal relapses. At the last visit, all had creatininaemia below 100 micromol/l except one woman with creatinine level 115 micromol/l, nine had proteinuria >0.5 g/day, and one was treated for hypertension. CONCLUSION: Pregnancy need not be discouraged in women with a history of SLE nephritis with normal or mildly impaired renal function. Deterioration of renal function rarely occurs. However, these pregnancies are at high risk of pre-eclampsia and prematurity.

Adolescent↗

PubMed2001

Critical velocity of floatables in combined sewer overflow (CSO) chambers.

Although the efficiency of underflow baffles has never been clearly proven, these underflow baffles have gained in popularity over the last few years as a viable means to intercept floatables in Combined Sewer Overflows (CSOs). These pilot scale essays, performed in a 17.0 metres basin at various flowrates, show that a critical horizontal velocity (V(CR)) may develop in the overflow chamber. Whenever this critical velocity is exceeded, floatables that would normally rise to the surface are kept within the flow and never intercepted, thus rendering the underflow baffle ineffective. The equation relating the critical horizontal velocity to the vertical velocity is found to be: V(CR) = 16 w R(H) 1/6.

Models, Theoretical↗

PubMed2001

A study of 75 pregnancies in patients with antiphospholipid syndrome.

OBJECTIVE: To describe a French tertiary referral center experience in the treatment of pregnancies in patients with the antiphospholipid syndrome (APS). METHODS: Retrospective review of the data of 75 consecutive pregnancies in 47 women. RESULTS: After exclusion of induced abortions and pregnancies occurring before APS onset, the prior live birth rate was 7.9%. Forty-nine pregnancies occurred in women with history of vascular thrombosis, 17 with history of thrombocytopenia. Heparin was prescribed in 39 pregnancies, associated with aspirin in 35 cases, and aspirin alone was used in 36 as first-line therapy. Corticosteroids were prescribed in 38 pregnancies. Three pregnancies by in vitro fertilization led to one embryonic loss, one full term birth, and one premature birth. Six pregnancies treated with immunoglobulin ended in one fetal death, 2 premature and 3 full term deliveries. The outcome of the other 66 pregnancies was one embryonic loss, 8 fetal deaths, 16 prematurates, and 38 full term births. Use of corticosteroids correlated with severe prematurity (p = 0.005), preeclampsia (p = 0.014), intrauterine growth retardation (p = 0.005), and presence of disease associated to APS (p = 0.009). After exclusion of one fetal death associated with congenital anomaly, live birth rate was 72.9%. There was a trend for higher rate of fetal survival in patients without history of vascular thrombosis (84.6 vs 66.4%; p = 0.11). CONCLUSION: Obstetrical prognosis in APS was improved by antithrombotic therapy. Studies are needed to define individual risk and specific significance of the various antiphospholipid antibodies, in order to improve the respective indications for aspirin alone or with heparin in women without thrombotic events.

Adult↗

PubMed2000

[Materno-fetal platelet allo-immunization revealed by in utero intracerebral fetal hemorrhage: proposed management for the next pregnancy].

Materno-fetal platelet allo-immunization causes fetal or neonatal thrombocytopenia and sometimes severe intracerebral bleeding. The HPA-1s antigen is most generally implicated. This accident can occur during the first pregnancy with a major risk of severe recurrence during the next pregnancy. These women require specific care in a specialized center although no consensus has been reached on management of second pregnancies. Proposed treatments include immunoglobulins and/or corticosteroids, fetal blood puncture and unique or iterative platelet transfusions.

Abortion, Therapeutic↗

PubMed2000

H107, a new aminoglycoside anti-Pseudomonas antibiotic produced by a new strain of Spirillospora.

Spirillospora spp. (strain 719) has been the source of several antibiotics. One of these designated H107 is produced as a trace. Compared with other antibiotics produced by the same strain, it was obtained only from the broth filtrate after precipitation with acetic acid followed by extraction with n-butanol. It was a water soluble metabolite active against Gram-negative bacteria and especially Pseudomonas spp., and was identified as an aminoglycoside compound. This is the first report of aminoglycoside anti-Pseudomonas production by Spirillospora.

Actinomycetales↗

PubMed1999

Recurrent nonimmune hydrops fetalis: a rare presentation of sialic acid storage disease.

A case of recurrent hydrops fetalis, diagnosed on second trimester's ultrasonography, has led to the diagnosis of sialic acid storage disease. No classic etiology was found after the first accident. The recurrence in subsequent pregnancy raised the possibility of a storage disease that was confirmed by amniocentesis. The diagnosis of Salla's disease was based on high levels of free sialic acid in amniotic fluid and fetal cells culture and by specific histologic features on fetopathologic examination. Diagnosis of inherited diseases is important because it implies a high risk of recurrence which makes mandatory genetic counseling and prenatal care in subsequent pregnancies.

Adult↗

PubMed1998

Polyhydroxyalkanoates, biopolyesters from renewable resources: physiological and engineering aspects.

Polyhdroxyalkanoates (PHAs), stored as bacterial reserve materials for carbon and energy, are biodegradable substitutes to fossil fuel plastics that can be produced from renewable raw materials. PHAs can be produced under controlled conditions by biotechnological processes. By varying the producing strains, substrates and cosubstrates, a number of polyesters can be synthesized which differ in monomer composition. By this means, PHAs with tailored interesting physical features can be produced. All of them are completely degradable to carbon dioxide and water through natural microbiological mineralization. Consequently, neither their production nor their use or degradation have a negative ecological impact. After a historical review, possibilities for the synthesis of novel PHAs applying different micro-organisms are discussed, and pathways of PHA synthesis and degradation are shown in detail for important PHA producers. This is followed by a discussion of the physiological role of the accumulation product in different micro-organisms. Detection, analysis, and extraction methods of PHAs from microbial biomass are shown, in addition to methods for polyester characterization. Strategies for PHA production under discontinuous and continuous regimes are discussed in detail in addition to the use of different cheap carbon sources from the point of view of different PHA producing strains. An outlook on PHA production by transgenic plants closes the review.

Bacteria↗

PubMed1998

Can we advise ovulation induction in patients with SLE?

The prognosis of systemic lupus erythematosus (SLE) has greatly improved during the last two decades, now allowing most patients to have a very long survival including a satisfactory quality of life. Initially considered contraindicated in SLE due to its overwhelming risks, pregnancy is nowadays allowed in a majority of patients, and fair results are usually obtained under appropriate management (1-3). Consequently, patients thought to have infertility ask the question of a possible therapy, i.e. ovulation induction (OI) associated or not with in vitro fertilization (IVF). Considering the importance of estrogens in the pathogenesis of the disease, the use of such procedures raise several questions in SLE. Though data remain to date extremely scarce, the theoretical and practical aspects of OI in SLE will be briefly reviewed here.

Adult↗

PubMed1998

AH7, a non-polyenic antifungal antibiotic produced by a new strain of Streptosporangium roseum.

An antibiotic (AH7) produced by Streptosporangium roseum strain 214 was investigated. This compound was extracted with chloroform from the filtrate culture and purified using thin-layer chromatography and high pressure liquid chromatography procedures. The antibiotic strongly inhibited the growth of several strains of fungi and bacteria known to be plant and human pathogens. This compound differed from all other antibiotics known to be synthesized by Streptosporangium spp. Some of its chemical and physical properties resembled those of maytansines produced by Nocardia but the antibiotic AH7 has only antibacterial and antitumoral activities.

Actinomycetales↗

PubMed1998

[Evaluation of the association of a serum marker and second trimester ultrasonography for the screening of trisomy 21 in women of less than 38 years. Prospective study of 5,163 patients].

OBJECTIVES: Use of serum markers alone for trisomy 21 screening programs leads to a high rate of amniocentesis. Adding a second parameter (ultrasonography during the second trimester) might reduce this rate yet retain satisfactory sensitivity. This work was conducted to evaluate the pertinence of associating serum hCG level between 16 and 17 weeks gestation and morphological ultrasonography between 18 ans 20 weeks gestation. METHOD: A prospective study was conducted in 5,163 pregnant women aged over 38 years. A morphological ultrasonography was performed in all patients whose hCG level > 1/150 indicated a risk. An amniocentesis was proposed if an anomaly was detected at ultrasonography. RESULTS: Serum hCG was above the risk threshold retained in 11.9% of the patients and among these patients at least one anomaly was detected at ultrasonography in 12%. An amniocentesis was performed in 1.4% of all patients. The positive predictive value of the screening test was 20%. CONCLUSION: Combining a serum marker and ultrasonography during the second trimester allows a reduction in the rate of amniocentesis compared with screening with serum markers alone. Sensitivity for detecting trisomy 21 remains satisfactory.

Adult↗

PubMed1997

Purification and partial amino acid sequence of brevicin 27, a bacteriocin produced by Lactobacillus brevis SB27.

Brevicin 27, a bacteriocin produced by Lacto bacillus brevis SB27, is inhibitory mainly against closely related Lactobacillus brevis and Lactobacillus büchneri strains. It was purified from the culture supernatant by a four-step purification procedure including ammonium sulfate precipitation, cation exchange, hydrophobic interaction, and reverse-phase, high performance liquid chromatographies. The purified bacteriocin was subjected to mass spectrometry, amino acid composition analysis, and sequencing by Edman degradation. It was shown to be an about 5200-Da basic protein containing a high proportion of lysine and of hydrophobic amino acids. The partial N-terminal amino acid sequence (25 residues) was unique when compared with the Protein Data Bank (PDB), Swiss Prot, and Protein Information Resource(PIR) data banks and to the translated Gen Bank.

Amino Acid Sequence↗

PubMed1997

Characteristics and genetic determinants of bacteriocin activities produced by Carnobacterium piscicola CP5 isolated from cheese.

Carnobacterium piscicola CP5, isolated from a French mold-ripened soft cheese, produced a bacteriocin activity named carnocin CP5, which inhibited Carnobacterium, Enterococcus and Listeria spp. strains, and among the Lactobacillus spp. only Lactobacillus delbrueckii spp. [24]. The activity was purified by ammonium sulfate precipitation, anion exchange, and hydrophobic interaction chromatography followed by reverse-phase high-performance liquid chromatography (RP-HPLC). This latter step separated two peaks with anti-listerial activity (CP51 and CP52). Carnocin CP51 was partially sequenced, and the N-terminal part revealed the presence of the "pediocin-like consensus" sequence-Tyr-Gly-Asn-Gly-Val-. Then, a degenerated 24-mer oligonucleotide probe was constructed from the N-terminal sequence and used to detect the structural gene. It was localized on a plasmid of about 40 kb. Cloning of restriction fragments of this one, followed by DNA sequencing, revealed the presence of the second anti-Listeria bacteriocin gene (CP52). By comparing sequences in data banks and confirming results with PCR reactions, carnocin CP51 shared homologies with carnobacteriocin BM1, and carnocin CP52 was similar to carnobacteriocin B2, both produced by C. piscicola LV17 [2]. However, carnobacteriocin A from C. piscicola LV17 gene was lacking in C. piscicola CP5, and the two microorganisms have been isolated from different ecological environments: C. piscicola CP5 and C. piscicola LV17 were isolated from soft cheese and vacuum-packed meat respectively. This fact could allow different application perspectives for C. piscicola CP5.

Amino Acid Sequence↗