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1.
Sci Rep ; 12(1): 18981, 2022 11 08.
Article in English | MEDLINE | ID: mdl-36347900

ABSTRACT

We compared the outcomes of robotic-assisted partial nephrectomy (RPN) and open partial nephrectomy (OPN) using contemporary data to respond to unmet clinical needs. Data from patients included in the registry who underwent partial nephrectomy between January 01, 2014 and June 30, 2017 within 20 centres of the French Network for Research on Kidney Cancer UroCCR were collected (NCT03293563). Statistical methods included adjusted multivariable analyses. Rates of peri- and post-operative transfusion, and of surgical revision, were lower in the RPN (n = 1434) than the OPN (n = 571) group (2.9% vs. 6.0%, p = 0.0012; 3.8% vs. 11.5%, p < 0.0001; 2.4% vs. 6.7%, p < 0.0001, respectively). In multivariable analyses, RPN was independently associated with fewer early post-operative complications than OPN (overall: odds-ratio [95% confidence interval, CI] = 0.48 [0.35-0.66]; severe: 0.29 [0.16-0.54], p < 0.0001 for both) and shorter hospital stays (34% [30%; 37%], p < 0.0001). RPN was also a significantly associated with a decresedrisk of post-operative acute renal failure, and new-onset chronic kidney disease at 3 and 12 months post-surgery. There were no between-group differences in oncological outcomes. In comparison with OPN, RPN was associated with improved peri- and post-operative morbidity, better functional outcomes, and shorter hospital stays. Our results support the use of RPN, even for large and complex tumours.


Subject(s)
Kidney Neoplasms , Robotic Surgical Procedures , Humans , Kidney Neoplasms/surgery , Kidney Neoplasms/pathology , Nephrectomy/adverse effects , Nephrectomy/methods , Retrospective Studies , Robotic Surgical Procedures/adverse effects , Robotic Surgical Procedures/methods , Treatment Outcome
2.
J Hosp Infect ; 104(1): 40-45, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31419468

ABSTRACT

BACKGROUND: Pseudomonas aeruginosa remains one of the most common nosocomial pathogens in intensive care units (ICUs). Although exogenous acquisition has been widely documented in outbreaks, its importance is unclear in non-epidemic situations. AIM: To elucidate the role of exogenous origin of P. aeruginosa in ICU patients. METHODS: A chronological analysis of the acquisition of P. aeruginosa was performed using samples collected in 2009 in the DYNAPYO cohort study, during which patients and tap water were screened weekly. Molecular relatedness of P. aeruginosa isolates was investigated by pulsed-field gel electrophoresis. Exogenous acquisition was defined as identification of a P. aeruginosa pulsotype previously isolated from another patient or tap water in the ICU. FINDINGS: The DYNAPYO cohort included 1808 patients (10,402 samples) and 233 water taps (4946 samples). Typing of 1515 isolates from 373 patients and 375 isolates from 81 tap water samples identified 296 pulsotypes. Analysis showed exogenous acquisition in 170 (45.6%) of 373 patients. The pulsotype identified had previously been isolated from another patient and from a tap water sample for 86 and 29 patients, respectively. The results differed according to the ICU. CONCLUSION: Exogenous acquisition of P. aeruginosa could be prevented in half of patients. The overall findings of this survey support the need for studies on routes of transmission and risk assessment approach to better define how to control exogenous acquisition in ICUs.


Subject(s)
Disease Outbreaks/statistics & numerical data , Intensive Care Units/statistics & numerical data , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/isolation & purification , Cohort Studies , Cross Infection/epidemiology , Cross Infection/prevention & control , Disease Outbreaks/prevention & control , Electrophoresis, Gel, Pulsed-Field/methods , France/epidemiology , Genotype , Humans , Mass Screening/methods , Prospective Studies , Pseudomonas Infections/epidemiology , Pseudomonas aeruginosa/genetics , Risk Assessment , Water Microbiology
3.
Epidemiol Infect ; 146(12): 1556-1564, 2018 09.
Article in English | MEDLINE | ID: mdl-29945689

ABSTRACT

In the absence of perfect reference standard, classical techniques result in biased diagnostic accuracy and prevalence estimates. By statistically defining the true disease status, latent class models (LCM) constitute a promising alternative. However, LCM is a complex method which relies on parametric assumptions, including usually a conditional independence between tests and might suffer from data sparseness. We carefully applied LCMs to assess new campylobacter infection detection tests for which bacteriological culture is an imperfect reference standard. Five diagnostic tests (culture, polymerase chain reaction and three immunoenzymatic tests) of campylobacter infection were collected in 623 patients from Bordeaux and Lyon Hospitals, France. Their diagnostic accuracy were estimated with standard and extended LCMs with a thorough examination of models goodness-of-fit. The model including a residual dependence specific to the immunoenzymatic tests best complied with LCM assumptions. Asymptotic results of goodness-of-fit statistics were substantially impaired by data sparseness and empirical distributions were preferred. Results confirmed moderate sensitivity of the culture and high performances of immunoenzymatic tests. LCMs can be used to estimate diagnostic tests accuracy in the absence of perfect reference standard. However, their implementation and assessment require specific attention due to data sparseness and limitations of existing software.


Subject(s)
Campylobacter Infections/diagnosis , Diagnostic Tests, Routine/standards , Diagnosis, Differential , Enzyme-Linked Immunosorbent Assay , Feces/microbiology , France , Humans , Immunoassay , Latent Class Analysis , Models, Statistical , Polymerase Chain Reaction , Reference Standards , Sensitivity and Specificity , Software
4.
PLoS One ; 13(3): e0193300, 2018.
Article in English | MEDLINE | ID: mdl-29522559

ABSTRACT

OBJECTIVE: To assess the role of environment, medical care and individual risks factors for P. aeruginosa colonization and infection. STUDY DESIGN AND SETTING: A French multicentric prospective study involved ten ICUs for a five months period. Every adult patient newly hospitalized in ICUs with no P. aeruginosa carriage up to 48 hours after admission was included and weekly screened before discharge or death. Screening swabs were either rectal, sputum or oropharyngeal samples. Hydric environment was also sampled each week. Data on patient clinical features, environmental and device exposures, and antibiotics supports were regularly collected. Multivariate analysis was performed with a multistate model. RESULTS: The overall prevalence of P. aeruginosa carriage was 15.3% (201/1314). Risk factors associated with patient colonization were: use of inactive antibiotics against P. aeruginosa (HR = 1.60 [1.15-2.21] p<0.01), tap water contamination at the entry in the room (HR = 1.66 [1.01-2.27] p<0.05) and mechanical invasive ventilation (HR = 4.70 [2.66-8.31] p<0.0001). Active antibiotics prevented from colonization (HR = 0.67 [0.48-0.93] p = 0.02) and from infection (HR = 0.64 [0.41-1.01] p = 0.05). Interaction between hydric environment antibiotics support was not statistically associated with patient colonization. CONCLUSION: Hydric contamination and antibiotics pressure seem to remain key independent risk factors in P. aeruginosa colonization. These results advocate the need to carry on preventive and targeted interventions toward healthcare associated infections.


Subject(s)
Cross Infection/epidemiology , Hospitalization , Intensive Care Units/statistics & numerical data , Pseudomonas Infections/epidemiology , Pseudomonas aeruginosa/physiology , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Cross Infection/drug therapy , Female , France/epidemiology , Humans , Incidence , Male , Middle Aged , Pseudomonas Infections/drug therapy , Pseudomonas aeruginosa/drug effects , Risk Factors
5.
J Clin Neurosci ; 22(6): 1012-7, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25891892

ABSTRACT

Our aim was to evaluate the association between magnetisation transfer imaging (MTI) parameters measured 30 to 45 days after a cerebrovascular insult and post-stroke functional outcome at the same time. MTI offers the opportunity to depict subtle microstructural changes in infarcted areas. The clinical significance of the heterogeneity of brain damage within ischaemic stroke lesions is unknown. We prospectively included 58 patients with acute middle cerebral artery stroke. Diffusion-weighted imaging was performed within 12 hours after onset and the final infarct was documented by MRI with fluid-attenuated inversion recovery (FLAIR) and MTI at 30 to 45 days follow-up. We evaluated the association between MTI histogram parameters and the clinical outcome assessed by dichotomised (threshold >2) modified rankin scale (mRS) using multivariable logistic regression models adjusted on baseline characteristics. In multivariable analyses, stroke outcome was mostly driven by initial National Institutes of Health Stroke Scale (odds ratio [OR]=1.23; 95% confidence interval [CI]=1.07-1.41; p<0.01) while after adjustment of initial stroke severity magnetisation transfer ratio peak position was the only MRI parameter associated with functional status at 30 to 45 days post-stroke (OR=0.86; 95% CI=0.75-0.98; p=0.02); lower peak position values associated with higher mRS. Conversely, stroke volume measured on FLAIR sequence was not associated with stroke prognosis (p=0.87). The intensity of microstructural changes within the infarct core measured at 30 to 45 days follow-up is independently associated with the functional status evaluated at the same time. MTI and related parameters could be used as surrogate markers of treatment response in stroke clinical trials.


Subject(s)
Infarction, Middle Cerebral Artery/pathology , Recovery of Function , Aged , Diffusion Magnetic Resonance Imaging , Female , Humans , Infarction, Middle Cerebral Artery/complications , Logistic Models , Male , Middle Aged , Prognosis , Time Factors , United States
6.
Diagn Microbiol Infect Dis ; 82(1): 14-9, 2015 May.
Article in English | MEDLINE | ID: mdl-25753079

ABSTRACT

Chlamydia trachomatis, Neisseria gonorrhoeae, and Mycoplasma genitalium screening during pregnancy is not performed routinely in France. We conducted the first prospective study in 1004 women attending for routine antenatal care to determine the prevalence and risk factors for these bacterial infections. The overall prevalence of C. trachomatis, N. gonorrhoeae, and M. genitalium infections was 2.5%, 0%, and 0.8%, respectively. In patients aged 18-24 years, the prevalence increased to 7.9% for C. trachomatis and to 2.4% for M. genitalium. C. trachomatis infection was associated with age ≤24 years or being single or having more than 5 sexual partners in a lifetime. M. genitalium infection was more frequent in patients aged ≤24 years or who had a history of abortion or their first sexual intercourse after 20 years of age. The high prevalence of C. trachomatis in pregnant women aged ≤24 years, mostly asymptomatic, suggests that systematic screening could be beneficial.


Subject(s)
Chlamydia Infections/epidemiology , Diagnostic Tests, Routine/methods , Gonorrhea/epidemiology , Mycoplasma Infections/epidemiology , Pregnancy Complications, Infectious/diagnosis , Prenatal Diagnosis/methods , Adolescent , Adult , Age Factors , Chlamydia Infections/diagnosis , Chlamydia trachomatis/isolation & purification , Female , France/epidemiology , Gonorrhea/diagnosis , Humans , Mycoplasma Infections/diagnosis , Mycoplasma genitalium/isolation & purification , Neisseria gonorrhoeae/isolation & purification , Pregnancy , Prevalence , Prospective Studies , Young Adult
7.
Ann Oncol ; 26(1): 193-198, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25361987

ABSTRACT

BACKGROUND: Patients with advanced B-cell non-Hodgkin's lymphoma (NHL) refractory to initial chemotherapy or relapsing after autologous stem-cell transplantation have a poor prognosis. Allogeneic stem-cell transplantation after reduced-intensity conditioning (RIC) regimen can be a therapeutic option. However, the high incidence of relapse remains a challenging issue. We speculated that the incorporation of (90)Y-Ibritumomab tiuxetan into a fludarabine-based RIC regimen would improve the lymphoma control without overwhelming toxicity. Our aim was to evaluate the safety of (90)Y-Ibritumomab tiuxetan in association with such a regimen in a prospective multicenter phase II trial. PATIENTS AND METHODS: Thirty-one patients with advanced lymphoma from five distinct institutions were included between February 2008 and October 2010. Thirty patients in complete or partial response after failure of a median of 3 (range, 2-4) previous chemotherapy regimens including autologous transplant in 29 were evaluable for nonrelapse mortality (NRM) at day 100 post-transplant that was the primary end point. RESULTS: With a median follow-up of 32 months (range, 29-60 months), the 2-year event-free and overall survivals of the whole study group were both 80% [95 confidence interval (CI) 60.8% to 90.5%). The 100-day and 2-year post-transplant cumulative incidences of NRM were 3.3% (95% CI 0.2% to 14.9%) and 13.3% (95% CI 5.4% to 33.2%), respectively. The 2-year cumulative incidence of relapse was 6.7% (95% CI 1.7% to 25.4%). The cumulative incidences of grade II-IV and extensive chronic graft-versus-host disease were 27% and 14%, respectively. CONCLUSIONS: For chemosensitive advanced high-risk B-cell lymphoma, the addition of (90)Y-Ibritumomab tiuxetan to a RIC regimen based on fludarabine, busulfan and antithymocyte globulin followed by allogeneic transplant is safe and highly effective. clinicaltrials.gov: NCT00607854.


Subject(s)
Antibodies, Monoclonal/therapeutic use , Antilymphocyte Serum/therapeutic use , Busulfan/therapeutic use , Lymphoma, B-Cell/drug therapy , Vidarabine/analogs & derivatives , Adult , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Disease-Free Survival , Female , Graft vs Host Disease , Humans , Lymphoma, B-Cell/surgery , Male , Middle Aged , Neoplasm Recurrence, Local , Prospective Studies , Salvage Therapy , Stem Cell Transplantation , Transplantation Conditioning , Transplantation, Homologous , Treatment Outcome , Vidarabine/therapeutic use
8.
J Hosp Infect ; 88(2): 103-8, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25155240

ABSTRACT

BACKGROUND: Pseudomonas aeruginosa is a major nosocomial pathogen in intensive care units (ICUs); however, endogenous versus exogenous origin of contamination remains unclear. AIM: To identify individual and environmental ICU risk factors for P. aeruginosa acquisition. METHODS: A five-month prospective multicentric study was performed in ten French ICUs. Adult patients hospitalized in ICU for ≥ 24 h were included and screened for P. aeruginosa colonization on admission, weekly and before discharge. P. aeruginosa acquisition was defined by a subsequent colonization or infection if screening swabs on admission were negative. Water samples were obtained weekly on water taps of the ICUs. Data on patient characteristics, invasive devices exposure, antimicrobial therapy, P. aeruginosa water and patient colonization pressures, and ICU characteristics were collected. Hazard ratios (HRs) were estimated using multivariate Cox model. FINDINGS: Among the 1314 patients without P. aeruginosa on admission, 201 (15%) acquired P. aeruginosa during their ICU stay. Individual characteristics significantly associated with P. aeruginosa acquisition were history of previous P. aeruginosa infection or colonization, cumulative duration of mechanical ventilation and cumulative days of antibiotics not active against P. aeruginosa. Environmental risk factors for P. aeruginosa acquisition were cumulative daily ward 'nine equivalents of nursing manpower use score' (NEMS) [hazard ratio (HR): 1.47 for ≥ 30 points; 95% confidence interval (CI): 1.06-2.03] and contaminated tap water in patient's room (HR: 1.76; CI: 1.09-2.84). CONCLUSION: Individual risk factors and environmental factors for which intervention is possible were identified for P. aeruginosa acquisition.


Subject(s)
Cross Infection/etiology , Drug Resistance, Bacterial , Equipment Contamination , Intensive Care Units , Pseudomonas Infections/etiology , Respiration, Artificial/adverse effects , Water Microbiology , Adult , Aged , Anti-Bacterial Agents/therapeutic use , Cross Infection/microbiology , Female , France/epidemiology , Humans , Male , Middle Aged , Prospective Studies , Pseudomonas Infections/epidemiology , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/drug effects , Risk Factors
9.
HIV Med ; 15(1): 30-9, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24007567

ABSTRACT

OBJECTIVES: Combining noninvasive tests increases diagnostic accuracy for staging liver fibrosis in hepatitis C virus (HCV)-infected patients, but this strategy remains to be validated in HIV/HCV coinfection. We compared the performances of transient elastography (TE), Fibrotest (FT), the aspartate aminotransferase-to-platelet ratio index (APRI) and two algorithms combining TE and FT (Castera) or APRI and FT (SAFE) in HIV/HCV coinfection. METHODS: One hundred and sixteen HIV/HCV-coinfected patients (64% male; median age 44 years) enrolled in two French multicentre studies (the HEPAVIH cohort and FIBROSTIC) for whom TE, FT and APRI data were available were included in the study. Diagnostic accuracies for significant fibrosis (METAVIR F ≥ 2) and cirrhosis (F4) were evaluated by measuring the area under the receiver-operating characteristic curve (AUROC) and calculating percentages of correctly classified (CC) patients, taking liver biopsy as a reference. RESULTS: For F ≥ 2, both TE and FT (AUROC = 0.87 and 0.85, respectively) had a better diagnostic performance than APRI (AUROC = 0.71; P < 0.005). Although the percentage of CC patients was significantly higher with Castera's algorithm than with SAFE (61.2% vs. 31.9%, respectively; P < 0.0001), this percentage was lower than that for TE (80.2%; P < 0.0001) or FT (73.3%; P < 0.0001) taken separately. For F4, TE (AUROC = 0.92) had a better performance than FT (AUROC = 0.78; P = 0.005) or APRI (AUROC = 0.73; P = 0.025). Although the percentage of CC patients was significantly higher with the SAFE algorithm than with Castera's (76.7% vs. 68.1%, respectively; P < 0.050), it was still lower than that for TE (85.3%; P < 0.033). CONCLUSIONS: In HIV/HCV-coinfected patients, TE and FT have a similar diagnostic accuracy for significant fibrosis, whereas for cirrhosis TE has the best accuracy. The use of the SAFE and Castera algorithms does not seem to improve diagnostic performance.


Subject(s)
Algorithms , Coinfection , Elasticity Imaging Techniques/methods , HIV Infections/complications , Hepatitis C/complications , Liver Cirrhosis/diagnosis , Adult , Area Under Curve , Biomarkers/blood , Female , Humans , Liver Cirrhosis/pathology , Male , Middle Aged , Predictive Value of Tests , ROC Curve , Sensitivity and Specificity
10.
Rev Epidemiol Sante Publique ; 61(3): 261-8, 2013 Jun.
Article in French | MEDLINE | ID: mdl-23639687

ABSTRACT

BACKGROUND: The main source of key medical information consists in original articles published in peer-reviewed biomedical journals. Reported studies use increasingly sophisticated statistical and epidemiological approaches that first require a solid understanding of core methods. However, such understanding is not widely shared among physicians. Our aim was to assess whether the basic statistical and epidemiological methods used in original articles published in general biomedical journals are taught during the first years of the medical curriculum in France. METHODS: We selected original articles published in The New England Journal of Medicine, The Lancet, and The Journal of the American Medical Association, over a period of six months in 2007 and in 2008. A standardized statistical content checklist was used to extract the necessary information in the "Abstract", "Methods", "Results", footnotes of tables, and legends of figures. The methods used in the selected articles were compared to the national program and the public health program of biostatistics and epidemiology taught during the first six years of medical school. RESULTS: The 237 analyzed original articles all used at least one statistical or epidemiological method. Descriptive statistics, confidence interval and Chi(2) or Fisher tests, methods used in more than 50% of articles, were repeatedly taught throughout the medicine curriculum. Measures of association, sample size, fit and Kaplan-Meier method, used in 40 to 50% of articles, were specifically taught during training sessions on critical reading methods. Cox model (41% of articles) and logistic regression (24% of articles) were never taught. The most widely used illustrations, contingency tables (92%) and flowcharts (48%), were not included in the national program. CONCLUSION: More teaching of the core methods underlying the understanding of sophisticated methods and illustrations should be included in the early medical curriculum so that physicians can read the scientific literature critically for their medical education.


Subject(s)
Biomedical Research/education , Biomedical Research/statistics & numerical data , Education, Medical, Undergraduate , Research Design/statistics & numerical data , Checklist , Comprehension , Curriculum/standards , Epidemiologic Methods , France , Humans , Peer Review , Publishing/statistics & numerical data , Reading
11.
AJNR Am J Neuroradiol ; 32(2): 352-8, 2011 Feb.
Article in English | MEDLINE | ID: mdl-20966063

ABSTRACT

BACKGROUND AND PURPOSE: Stroke volume, an increasingly used end point in phase II trials, is considered stationary at least 30 days after the ictus. We investigated whether information conveyed by MR imaging measurements of the "final" infarct volume could be assessed as early as the subacute stage (days 3-6), rather than waiting for the chronic stage (days 30-45). MATERIALS AND METHODS: Ninety-five patients with middle cerebral artery stroke prospectively included in a multicenter study underwent MR imaging during the first 12 hours (MR imaging-1), between days 3 and 6 (MR imaging-2), and between days 30 and 45 (MR imaging-3). We first investigated the relationship between subacute (FLAIR-2) and chronic volumes (FLAIR-3), by using a linear regression model. We then tested the relationship between FLAIR volumes (either FLAIR-2 or FLAIR-3) and functional disability, measured by the mRS at the time of MR imaging-3, by using logistic regression. The performances of the models were assessed by using the AUC in ROC. RESULTS: A linear association between log FLAIR-2 and log FLAIR-3 volumes was observed. The proportion of FLAIR-3 variation, explained by FLAIR-2, was high (R(2) = 81%), without a covariate that improved this percentage. Both FLAIR-2 and FLAIR-3 were independent predictors of mRS (OR, 0.79 and 0.73; 95% CI, 0.64-0.97 and 0.56-0.96; P = .026 and .023). The performances of the models for the association between either FLAIR volume and mRS did not differ (AUC = 0.897 for FLAIR-2 and 0.888 for FLAIR-3). CONCLUSIONS: Stroke damage may be assessed by a subacute volume because subacute volume predicts the "true" final volume and provides the same clinical prognosis.


Subject(s)
Brain/pathology , Cerebral Infarction/pathology , Infarction, Middle Cerebral Artery/pathology , Magnetic Resonance Imaging/methods , Acute Disease , Aged , Brain Ischemia/pathology , Chronic Disease , Disease Progression , Female , Humans , Linear Models , Logistic Models , Magnetic Resonance Angiography , Male , Middle Aged , Predictive Value of Tests , Prognosis , Prospective Studies
12.
Aliment Pharmacol Ther ; 30(3): 283-93, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19438427

ABSTRACT

BACKGROUND: The pathogenesis of Crohn's disease (CD) involved microbial factors. Some Helicobacter species, the so-called entero-hepatic Helicobacters (EHH), can naturally colonize the intestinal surface and have been detected in humans. Aim To look for an association between CD and the presence of EHH DNA in intestinal biopsies. METHODS: Two groups of patients were included prospectively in a multicentre cross-sectional study: CD patients with an endoscopic post-operative recurrence within 2 years following a surgical resection and controls screened for colorectal polyps or cancer. Intestinal biopsies were taken for Helicobacter culture and Helicobacter 16S DNA detection. If positive, the EHH species were identified with specific PCRs, sequencing and denaturing gradient gel electrophoresis. RESULTS: In the 165 included patients (73 CD and 92 controls), Helicobacter cultures were negative. PCR was positive in 44% of CD and 47% of controls. After age-adjustment, CD was significantly associated with EHH in intestinal biopsies (OR = 2.58; 95%CI: 1.04-6.67). All EHH species detected were identified as Helicobacter pullorum and the closely related species Helicobacter canadensis. CONCLUSION: Crohn's disease is associated with the presence of EHH species DNA in intestinal biopsies after adjustment for age. Whether these species play a role in the pathophysiology of CD remains to be determined.


Subject(s)
Crohn Disease/microbiology , DNA, Bacterial/analysis , Helicobacter Infections/pathology , Helicobacter/genetics , Intestinal Mucosa/pathology , Adolescent , Adult , Aged , Biopsy/methods , Crohn Disease/pathology , Cross-Sectional Studies , Female , Helicobacter Infections/genetics , Humans , Intestinal Mucosa/microbiology , Male , Middle Aged , Polymerase Chain Reaction , Prospective Studies , RNA, Ribosomal, 16S/analysis , Young Adult
13.
Rev Epidemiol Sante Publique ; 55(3): 213-20, 2007 Jun.
Article in French | MEDLINE | ID: mdl-17467942

ABSTRACT

BACKGROUND: When the sensitivity of an assay used to quantify a marker is poor, some of the values are below the detection limit resulting in left-censoring. Analysis of such data requires appropriate statistical techniques. In this study, we aimed at comparing various methods used to deal with left-censored outcome in regression analysis. METHODS: The application was a real study evaluating the performance of procalcitonin for the diagnosis of bacterial infections among elderly patients. Among 85 patients, eleven had a procalcitonin value below the detection limit. A simulation study was then performed with data sampled according to a Gaussian distribution with parameters estimated on observed data. Various levels of left-censoring were simulated (13, 25 and 50%). A linear regression model was used to explain procalcitonin variations according to another marker, C reactive protein. To handle left-censoring, several methods were used: complete case analysis, simple imputation and multiple imputation methods, and parametric modelling. In the simulation study, estimations according to different methods were compared in terms of bias and mean square error according to each left-censoring level. Estimations obtained with real data were also compared according to the methods used. All analyses were implemented using SAS software. RESULTS: In the simulation study, parametric modelling using maximum likelihood showed best performances whatever the level of censoring. On the other hand, methods using complete cases and simple imputation by the detection limit were highly skewed. On observed data, estimations of the slope varied slightly according to the methods. However the p-values (Wald test) of beta=0 varied from 0.0001 to 0.13 leading to different decisions according to the method used. CONCLUSION: Left-censoring handling in data analysis requires special attention, as different methods may yield results leading to different conclusions.


Subject(s)
Biometry , Calcitonin/blood , Models, Statistical , Protein Precursors/blood , Biomarkers/blood , Calcitonin Gene-Related Peptide , Humans , Linear Models
14.
Front Biosci ; 3: e164-74, 1998 Oct 01.
Article in English | MEDLINE | ID: mdl-9751667

ABSTRACT

Mycobacterial lipids have been studied for more than 70 years, due to the fascinating diversity of their structures and biological activities. A historical perspective, and the present status on the structure and activity of major lipids of the outer envelope of mycobacterial cells are presented : mycolic acids, which are main constituents of the cell wall, and glycolipids known for toxic or immunological properties (cord factor, SL, DAT, PGL, GPL, LOS, LAM). As far as possible, it was tried to distinguish between experimentally established knowledge and currently accepted speculations.


Subject(s)
Evolution, Molecular , Lipids/genetics , Mycobacterium/chemistry , Carbohydrate Sequence , Lipids/chemistry , Molecular Structure
17.
Res Microbiol ; 141(5): 599-607, 1990 Jun.
Article in French | MEDLINE | ID: mdl-2218063

ABSTRACT

Chemotaxonomic identification of coryneform bacteria metabolizing b-caryophyllene was attempted. The following phospholipids were identified as main components of the bacterial extracts: cardiolipids, phosphatidylethanolamine, phosphatidylinositol and mannosides of phosphatidylinositol. Saponification of the lipid extracts gave a mixture of hydroxylated and nonhydroxylated fatty acids. Among the latter, oleic and tuberculostearic acids were identified. The hydroxylated fatty acids were analysed by thin-layer chromatography and mass spectrometry (as methyl esters). From the results thus obtained, the strains appeared to be more closely related to the genus Rhodococcus than to the genus Nocardia.


Subject(s)
Gram-Positive Bacteria/classification , Lipids/analysis , Rhodococcus/classification , Sesquiterpenes/metabolism , Chromatography, Gas , Chromatography, Thin Layer , Fatty Acids/analysis , Gram-Positive Bacteria/metabolism , In Vitro Techniques , Mycolic Acids/analysis , Polycyclic Sesquiterpenes , Rhodococcus/metabolism
18.
Biochem Cell Biol ; 68(1): 379-86, 1990 Jan.
Article in French | MEDLINE | ID: mdl-2350500

ABSTRACT

To increase the application of lipid analysis for taxonomic purposes, a standardized method would be useful. This method has to be simple enough to be used routinely. Such a method, based on thin-layer and gas chromatography, is proposed. It can be applied to any kind of bacteria when a few milligrams of cells are available. Comparison of the results provided by this analysis with data found in the literature (given in a schematic form in six tables) allows the identification of the studied strain in the most favorable cases, or gives information for the choice of conclusive complementary tests in the other cases.


Subject(s)
Bacteria/classification , Lipids/analysis , Bacteria/analysis , Chromatography, Gas , Chromatography, Thin Layer , Lipids/isolation & purification
19.
Ann Inst Pasteur Microbiol ; 139(2): 159-70, 1988.
Article in French | MEDLINE | ID: mdl-3408592

ABSTRACT

The free lipids of Flavobacterium meningosepticum were separated by thin layer chromatography, and the main lipid fractions were analysed by FAB (fast atom bombardment) mass spectrometry. The major products were di-iso-C15- and iso-C15-iso-C17-phosphatidylethanolamine, and two ninhydrin + and phosphorus- fractions. The structures of the latter two fractions were established as ornithine lipids by using MIKE (mass ions kinetic energy) mass spectrometry, GC/MS (gas chromatography coupled with mass spectrometry) and conventional methods. The presence of small amounts of sphingolipids with C17- and C16-sphinganines was demonstrated. F. meningosepticum can be distinguished from F. multivorum and F. spiritivorum by easy characterization of the ornithine lipids by thin layer chromatography.


Subject(s)
Flavobacterium/analysis , Lipids/analysis , Chemical Phenomena , Chemistry , Chromatography, Thin Layer , Gas Chromatography-Mass Spectrometry , Mass Spectrometry
20.
Ann Inst Pasteur Microbiol (1985) ; 137A(1): 65-78, 1986.
Article in French | MEDLINE | ID: mdl-3674781

ABSTRACT

Thirty strains were isolated from pasteurized soil samples by enrichment culture in aerobiosis at 32 degrees C in a minimal medium containing one of the following compounds as sole source of carbon and energy: quinate, p-hydroxybenzoate, phthalate, isophthalate or trimellitate. These bacteria were rods (0.8 X 2-7 micron), motile by peritrichous flagella. Endospores were oval (1.4-1.8 X 2 micron) and distinctly swelled the sporangia. The Gram reaction was variable but the Gram type was positive. Colonies were smaller on peptone (0.4%) agar than on minimal salts-glucose (0.2%) agar. The following characters were always present: growth in the presence of lysozyme, cytochrome c oxidase, catalase, nitrate assimilation, urease, amylase and L-glutamate dehydrogenase. The cells contained glycogen. In anaerobiosis, glucose was not fermented and nitrate was not used as a respiratory acceptor of electrons. Of 215 substrates tested, 31 (including 9 aromatic compounds) were used as sole carbon and energy sources by all 30 strains, and 38 substrates (including 13 aromatic compounds) were used by only some of them; 146 substrates (including 49 aromatic compounds) were not used by any of the 30 strains. No amino acid could be used as sole carbon and energy source. Numerical analysis of the 30 strains showed an aggregate cluster made of 5 phena. The mean G + C content of the DNA was 55 +/- 0.6 mol %. The described bacteria are clearly different from the 2 known species of the second morphological group which cannot ferment carbohydrates: Bacillus brevis and B. azotoformans. Strain Q1 (ATCC 29948) is the holotype of Bacillus gordonae sp. nov.


Subject(s)
Bacillus/ultrastructure , Bacillus/classification , Bacillus/metabolism , Microscopy, Electron
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