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F Dubois

Publications and source records attributed to F Dubois.

At least 37 records · Page 2Linked to original sources
PubMed2000

Pair-bonding in birds and the active role of females: a critical review of the empirical evidence.

Over the recent years the role of females in maintaining or breaking the pair-bond in socially monogamous birds has received growing attention. Here, we review the overall evidence for a direct and predominant role of female behaviour in initiating or preventing divorce and its relevance for the understanding of both interspecific and intraspecific variation in divorce rate in monogamous bird species. The evidence is so far limited to a few species. We discuss the relevance of some alternative explanations and confounding factors. We conclude that the possible predominance of females in both initiating divorce or limiting its occurrence deserves further consideration. Future studies should favour experimental approaches, such as mate-removal experiments.

Journal Article↗
PubMed2000

[Diagnosis and biological surveillance of hepatitis C virus infections].

HCV-specific laboratory assays are broadly used to establish the diagnosis, to survey viral replication and to monitor anti-viral treatments. Third-generation ELISA's have an excellent sensitivity well adapted to the early diagnosis. Positive or dubious screening tests must be controlled on a second blood sample. We recommend the use of an immunoblot assay for this control. Regular survey of the immunoblot profile may facilitate the identification of recent infections and help distinguish between active or resolutive infections. PCR assays which detect HCV ARN in serum are very usefull to decide and monitor anti-viral treatments. Their cut-off is usually in the range of 100 genomes/mL. Quantitative assays to measure viral load may also rely on PCR technology or be based on the so-called "branched DNA" technology slightly less sensitive. Genotyping or serotyping of HCV is crucial to adapt specific treatment protocols to the less responsive genotypes 1a et 1b. Cloning and sequencing of HCV isolates is necessary to explore nosocomial clusters of infections or intra-familial cases.

Antiviral Agents↗
PubMed2000

Biphasic effect of UVA radiation on STAT1 activity and tyrosine phosphorylation in cultured human keratinocytes.

The effect of ultraviolet A (UVA) radiation on the DNA-binding activity of the transcription factor STAT1 was studied by electromobility shift assay in the human keratinocyte cell line NCTC 2544. The STAT1-binding activity exhibited a biphasic pattern as a function of UVA doses. For UVA doses lower than 0.6 J/cm(2), a dose-dependent increase in STAT1 activity was observed. In a second phase, with higher UVA doses (1.5 to 9 J/cm(2)), the activity decreased and reached control value at 6 J/cm2. The enhancement of STAT1 activity was transient, peaked at 1 h after UV irradiation, and regularly decreased to control value 24 h after UV. Genistein, a tyrosine kinase inhibitor, H7, a serine/threonine kinase inhibitor, and PD 98059, a MEK inhibitor, prevented the UVA-induced enhancement of STAT1-binding activity, suggesting the involvement of Tyr, Ser/Thr kinases, and MEK in the observed effect. Immunoblot analysis directly demonstrated that the amount of Tyr-phosphorylated STAT1 was parallel to its DNA-binding activity. Immunoblot analysis also demonstrated the nuclear transport of STAT1 after UVA irradiation at low doses. At high doses, a decrease in the STAT1 level was observed both in the cytoplasmic and the nuclear compartments, suggesting that the inactivation was due to a degradation process. UVA irradiation initiated a dose-dependent increase in lipid peroxidation products and reactive oxygen species. Furthermore, the involvement of the oxidative stress in the UVA-induced effect on STAT1 activity is suggested by the protective action of the antioxidants alpha-tocopherol and N-acetylcysteine on both the activation phase (UVA doses lower than 1.5 J/cm(2)) and the inhibitory phase. By contrast, the pro-oxidant drug buthionine sulfoximine enhanced the effect of UVA on STAT1-binding activity. Since STATs are known as transducers of cytokine action, the enhancement of STAT1 activity by low doses of UVA might be related to the proinflammatory effect of solar radiations at the skin level.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2000

A MALDI sample preparation method suitable for insoluble polymers

Polyamides are insoluble or poorly soluble in common organic solvents, which makes normal sample preparation for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry very difficult. An new analytical protocol for MALDI analysis of polyamides or other insoluble samples is described. It consists of pressing a pellet from a solid mixture of the polymer and a matrix, both in the form of finely ground powder. This sample preparation is compared with the common dried droplet sample preparation method and found to perform much better, both in terms of robustness against variation of experimental parameters and high-mass capability.

Journal Article↗
PubMed2000

Is mate fidelity related to site fidelity? A comparative analysis in Ciconiiforms.

We tested for an association between divorce rate and site fidelity in 42 avian species belonging to the order Ciconiiforms, using comparative methods that account for the influences of phylogenetic relationships on the data. Our methods enabled us to detect evidence of correlated evolution and provided information on the temporal ordering of evolutionary changes in these two variables. We found a significant correlation between divorce rate and site fidelity, indicating that species with little or no site fidelity are more likely to divorce. Our data suggest that the coupled evolution of divorce and site fidelity can be summarized by three major events. The first event corresponds to a transition from species showing high divorce rate and low or no site fidelity to species that tended to reuse the same nests over consecutive breeding seasons. This was followed by a transition towards higher mate fidelity, with the preservation of pair bonds over consecutive breeding attempts. In a third stage, divorce rate and the rate of site fidelity varied, independently of each other. We discuss our results within the context of the ancestor species and the past environments in which the traits originated, and address the importance of the potential for individual recognition in shaping the observed patterns of covariation between mate fidelity and site fidelity in Ciconiiforms. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Contribution of ultrasonography and cholescintigraphy to the diagnosis of acute acalculous cholecystitis in intensive care unit patients.

OBJECTIVES: To assess the respective value of ultrasonography (US) and morphine cholescintigraphy (MC) in the diagnosis of acute acalculous cholecystitis (AAC). DESIGN AND SETTING: Prospective study in an intensive care unit of a university hospital. PATIENTS AND INTERVENTION: Twenty-eight patients with clinically and biologically suspected of AAC. US was performed at the bedside and less than 12 h later MC. US was considered positive if three major criteria were present: wall thickness greater than 4 mm, hydrops, sludge; MC results were regarded as positive if the gallbladder could not be visualized. These latter patients underwent cholecystectomy and the diagnosis of AAC was confirmed through histopathological study. MEASUREMENTS AND MAIN RESULTS: Sensitivity of US and MC, respectively, was 50% and 67%, specificity 94% and 100%, positive predictive value 86% and 100%, negative predictive value 71% and 80%, and accuracy 75% and 86%. The correlation between US and MC findings was 71%, with chi = 0.31. By Bayesian analysis the probability of disease if the MC finding was positive was 100% regardless of US results. A positive US finding was associated with a 86% probability of disease, but with a probability of only 66% in case of negative MC results. MC is thus superior to US for confirming AAC in selected critically ill patients. Nevertheless, US is an easy, noninvasive, and effective method of bedside screening. The combination of the two imaging tests improves diagnostic accuracy and reduces false-positive and false-negative rates. Poor agreement between the two tests leads to better diagnostic complementarity.

Acute Disease↗
PubMed2000

New surgical strategy for gastroduodenal ulcer: laparoscopic approach.

Although peptic gastroduodenal ulcers are rarely treated surgically today, when surgery is required a laparoscopic approach is possible with its well known advantages. The most widely used technique is vagotomy by various modalities. Training in laparoscopy requires good instrumentation to avoid complications. Vagotomy can be truncal and bilateral via laparoscopy or thoracoscopy, which is the easiest and quickest procedure; moreover, the sequelae are less important and less frequent, as has been reported. It can also be highly selective or mixed, such as the Taylor procedure; and large series have been reported with good results. Gastric resection is rarely used for peptic ulcers, although it is feasible laparoscopically; it requires a large experience. Long-term results of laparoscopic vagotomy are now available and have indicated the same results as are attained with open surgery.

Duodenal Ulcer↗
PubMed2000

Immunolocalization of glutamine synthetase in senescing tobacco (Nicotiana tabacum L.) leaves suggests that ammonia assimilation is progressively shifted to the mesophyll cytosol.

Glutamine synthetase (GS) catalyses the formation of glutamine (a major form of nitrogen transport in plants) in an ATP-dependent reaction using ammonium and glutamate. This enzyme is present in the plastids and/or in the cytosol depending on the plant or the organ examined. In order to understand the role of GS isoforms in the remobilization of leaf nitrogen, we studied the localization of GS isoenzymes during natural senescence of tobacco (Nicotiana tabacum L.) leaves. Parallel to the progression of leaf senescence, an increase in cytosolic GS polypeptides was detected in the mesophyll cytosol of senescing leaves while a significant decrease in GS protein content was observed in the phloem companion cells. The presence of GS polypeptides in the leaf cytosol of senescing leaves appears to be the result of an induction of the Gln1-3 gene, the transcripts of which are not detected in mature leaves but are abundant in senescing leaves. Alltogether, our results suggest that during senescence, ammonia assimilation is progressively shifted from the chloroplasts to the cytosol of leaf mesophyll cells.

Ammonia↗
PubMed2000

Involvement of the glutathione S-conjugate compounds and the MRP protein in Tc-99m-tetrofosmin and Tc-99m-sestamibi uptake in glioma cell lines.

The objective of this study was to compare the accumulation of Tc-99m-tetrofosmin and Tc-99m-sestamibi in four grade IV glioma cell lines and to correlate their accumulation with the multidrug resistance of the cells. Tc-99m-tetrofosmin in all glioma cell lines showed slightly higher uptake and more efficient release beyond 150 min than Tc-99m-sestamibi and the retention of both tracers in the cells was to a certain extend inversely proportional to their degree of multidrug resistance. The results obtained showed that the efflux of both tracers was carried out only in part through the MRP/GS-X pump system. Tc-99m-tetrofosmin showed good potential as a marker of recurrent malignant glioma and in vivo studies are currently underway to confirm these observations.

ATP-Binding Cassette Transporters↗
PubMed2000

[Interpretation of hepatitis C virus serology: immunoblot and genome amplification].

In France, screening for anti-hepatitis C virus (HCV) among blood donors has been performed since 1 March 1990. It is usually carried out using enzyme immunoassays (EIA). Positive or dubious results may be linked to false positive EIA reactions. Therefore the use of an immunoblot assay such as RIBA can be very useful to assess false positive signals. Moreover, the analysis of the different antibody reactivities makes it possible to evoke a viremic status or not. The follow-up provides essential information on recent seroconversion. However, some profiles do not allow a conclusion to be drawn between chronicity and serological sequel. In these cases, polymerase chain reaction (PCR) has to be implemented in order to conclude between the two.

Antibody Specificity↗
PubMed2000

Response

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Journal Article↗
PubMed2000

Hepatitis B exacerbation with a precore mutant virus following withdrawal of lamivudine in a human immunodeficiency virus-infected patient.

Chronic active hepatitis B exacerbations have been reported following development of resistance to or withdrawal of lamivudine in HIV-infected patients. A 38-year-old woman with HIV and chronic HBV infections was hospitalized because of acute hepatitis. The occurrence of cytolysis with replication of HBV 2 months after withdrawing lamivudine suggests that our patient experienced a severe reactivation of HBV infection due to the modification of her treatment. Sequencing of the HBV precore region showed the strain to be a mutant. We conclude that lamivudine should not be stopped in HIV- and HBV-infected patients, but could be continued at the dose of 100mg/day as used in isolated HBV infection.

Adult↗
PubMed2000

Two successive hepatitis C virus infections in an intravenous drug user.

We report the case of an occasional intravenous drug user who developed two successive hepatitis C virus (HCV) infections. The first infection led to seroconversion (anti-HCV antibodies detected) and the detection of HCV RNA in serum. After a spontaneous recovery (normalization of alanine aminotransferase levels and HCV RNA clearance), a second HCV infection was observed, with the recurrence of HCV viremia. Antibody directed against HCV serotype 1 was detected throughout the follow-up monitoring, but two different HCV strains were identified during the two infectious episodes: genotype 1a for the first and genotype 3a for the second. This observation shows that primary HCV infection does not confer protective immunity against subsequent infection with viruses of other genotypes. This may hamper the development of a vaccine. Conflicting results were obtained in genotyping and serotyping assays, suggesting that the serotyping method cannot be used to identify the HCV type in patients, such as intravenous drug users, who are exposed to successive HCV infections.

Adult↗
PubMed2000

[Stereotactic applications in third ventricle tumors].

Stereotactic procedures are especially indicated for deep lesions within the brain substance, surrounded by functional structures, such as third ventricle tumors. Despite recent technological advances, the basis for stereotaxis remains minimally traumatic procedures, with the safety of vascular and ventricular anatomical definitions. Stereotactic procedures were performed in 63 patients of the national series. The indications, procedures, results and complications were reviewed. Stereotaxis was used with a diagnosis purpose in 34 patients. In all cases, the histological diagnosis was identified, which allowed the definition of the therapeutic strategy, and avoidance of useless direct approach to the third ventricle. Stereotaxis was used with a therapeutic purpose in 29 other patients : the procedure allowed the evacuation of colloid or glial tumor cysts, ventriculostomy, intracavitary irradiation, or radiosurgery. The stereotactic procedure should take in account the grade of associated hydrocephalus. Stereotactic evacuation of colloid cysts in this series (25 cases) often resulted in a recurrence of the cyst. Endoscopic procedures, eventually associated with stereotactic guidance, should be preferred for the treatment of colloid cysts.

Cerebral Ventricle Neoplasms↗
PubMed2000

[Prevalence of infection by hepatitis viruses in a rural area. Analysis according to risk factors and alcohol consumption].

OBJECTIVES: To evaluate the prevalence of serum markers of hepatitis A, B and C viruses in a rural area according to risk factors and alcohol consumption. METHODS: Transversal study of unselected subjects living and working in a rural area. Each subject included was asked to fill out an anonymous self-administered questionnaire dealing with his own risk factors, sexual behaviour and alcohol consumption. A blood sample was collected for detection of HBsAg, anti-HBc, anti-HBs, anti-HAV and anti-HCV antibodies. RESULTS: Three hundred three subjects with a mean age of 48 years were included. Main risk factors for viral infection were: blood transfusion (9.4%), intravenous drug addiction (0.73%), acupuncture (17.5%), tattoos (5. 8%), past hospitalizations (71.5%), homosexuality (1.1%), conjugal unfaithfulness (11%), sexual partners >5 (21.3%). Most subjects with at risk sexual behaviour had sexual relations without protection. Anti-HAV prevalence was 87.2% (95% confidence interval 83.4-91.0%). None of the subjects was HBsAg positive and 6.0% (confidence interval 4.7-8.7%) had anti-HBV antibodies. HBV prevalence was correlated to homosexuality only. Two subjects (0.67%, confidence interval 0-1.6%) without any identified risk factor had anti-HCV antibodies. There was no correlation between serum viral marker positivity and an excess alcohol consumption (>80 g of ethanol/d) which was present in 46 subjects. However HBV prevalence was 28.6% in the seven subjects who had been treated for alcoholism; these 7 subjects had a highly at risk sexual behaviour. CONCLUSION: In a rural area, infection by HAV is very frequent. The prevalence of HBV and HCV did not greatly differ from that observed in the general and urban population. The frequent failure to use protection in subjects with at risk sexual behaviour reinforces the need of prevention programs in rural areas.

Adult↗
PubMed2000

[Detection of lymphatic metastasis from malignant melanoma after identification of the sentinel node by preoperative lymphoscintigraphy and intraoperative radioisotopic detection].

OBJECTIVES: The aim of this study was to evaluate the detection of the first lymph node draining the primary tumour site, using a radioisotopic mapping alone and to determine whether a preoperative lymphoscintigraphy using technetium sulfur colloid and a hand-held gamma detecting probe could improve the detection of the sentinel lymph node (SLN) in melanoma. PATIENTS AND METHOD: From January to December 1998, 36 patients with a cutaneous melanoma larger than 0.75 mm, stage I TNM were included in this prospective study. Mean Breslow was 1.85 mm. The distribution of melanoma was head and neck (n = 9), trunk (n = 7), upper extremities (n = 4), lower extremities (n = 16). Preoperative lymphoscintigram and intraoperative detection were used. The first hot lymph node was supposed to be the SLN. RESULTS: In all cases, a lymph node was found and nine patients had more than one SLN (average number of SLN per patient: 1.25). Aberrant drainages were found in seven patients (19.4%): 1 in-transit lymph node, three paradoxical bassins, three bypasses). Four out of 36 patients had lymph node metastases and underwent elective lymph node dissection. CONCLUSION: The radio-isotopic technique used alone for the identification of the SLN is efficient in melanoma with a 100% detection rate in this short series.

Adult↗
PubMed2000

[Results of elective segmental colectomy done with laparoscopy for complicated diverticulosis].

OBJECTIVES: To analyze a unicentric series of 100 consecutive elective laparoscopic colon resections for diverticular disease and to evaluate in intention to treat the early- and middle-term postoperative results. METHODS: From February 1993 to March 1998, 100 colon resections for complicated diverticular disease were performed through laparoscopy with systematic mobilization of the splenic flexure and resection of the rectosigmoid junction. The colorectal anastomosis was stapled or manual without proximal stoma. In 53 females and 47 males (mean age 60.4 years), indications for surgery were: one or more attacks of acute diverticulitis (n = 70), abscess (n = 17), symptomatic stenosis (n = 8), colovesical fistula (n = 4) and diverticular bleeding (n = 1). RESULTS: Mortality was nil. The conversion rate was 9%, never for anesthetic reasons. The mean operating time was 226 +/- 68 min. There was no splenic or ureteral injury. The morbidity at 30 days was 19% with fistulae rate accounting for 2%, 2 patients were reoperated on. The median time for passage of flatus was 3 days and median length of hospital stay was 7 days. Late morbidity was 10%, one patient complained of retrograde ejaculation. CONCLUSION: This study demonstrates that laparoscopy is a safe alternative to laparotomy for elective one-stage colectomy for complicated diverticular disease.

Adult↗