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C Boisson

Publications and source records attributed to C Boisson.

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

Changing heat and moisture exchangers after 96 hours rather than after 24 hours: a clinical and microbiological evaluation.

OBJECTIVE: The aim of this study was to determine whether changing heat and moisture exchangers (HMEs) every 96 hrs rather than 24 hrs would affect their efficacy to preserve the heat and moisture of inspiratory gases. The impact of a prolonged use of the HME on its microbial colonization was also assessed. DESIGN: Prospective cohort observational study. SETTING: Intensive care unit of a university hospital. PATIENTS: Thirteen consecutive patients with no previous history of respiratory disease requiring controlled mechanical ventilation with an HME for >4 days were evaluated. INTERVENTIONS: The same HME was used for 96 hrs in each patient. MEASUREMENTS AND MAIN RESULTS: In each patient, during the inspiration phase, the following measurements were performed: peak and mean airway pressures, mean values of temperature, and relative and absolute humidity of inspired gases. In each patient, measurements were performed after 1 hr of HME use and then daily up to the fourth day. On days 1 and 4, microbiological samples were obtained from the patients' bronchial secretions and the ventilator side of the HME. After 96 hrs of ventilation with the same HME, tracheal tube occlusion was never observed. Using the same HME for 96 hrs rather than 24 hrs did not affect its technical performances: temperature at 24 hrs: 32.2 +/- 1.5 degrees C (90.0 +/- 34.7 degrees F), at 96 hrs: 32.1 +/- 1.6 degrees C (89.8 +/- 34.9 degrees F); relative humidity at 24 hrs: 97.9 +/- 2%, at 96 hrs: 98.1 +/- 1.7%; absolute humidity at 24 hrs: 33.1 +/- 2.4 mg H2O/L, at 96 hrs: 33.0 +/- 2.5 mg H2O/L. This analysis was based on a total of 312 measurements performed on the 13 patients. Peak and mean airway pressures did not change during the 96-hr study period, with identical tidal and minute volumes in the study patients. On day 1, ten patients had a positive culture of their tracheal secretions at a colony count of > or = 10(3) colony forming units/mL. After 96 hrs of use with the same HME, only seven patients had a positive culture of their tracheal secretions. Cultures from the ventilator sides of the HMEs were all sterile (13/13) after 96 hrs of use. CONCLUSIONS: In patients free from previous chronic respiratory disorder and ventilated for neurologic reasons, changing the HME after 96 hrs rather than 24 hrs did not affect its technical performance in terms of heat and water preservation of ventilatory gases. There is also some indirect evidence of very little, if any, changes in the HME resistance. No bacterial colonization of the ventilator sides of the HMEs was observed after 96 hrs of use. However, other large clinical trials should be undertaken to confirm the safety of extending the time between HME changes.

Adult↗
PubMed2000

Calculation of acoustic radiation using equivalent-sphere methods

Among the methods generally used to solve a problem in the domain of acoustic radiation, the equivalent sources method offers an interesting alternative. It consists in replacing the vibrating surface with a distribution of acoustic sources placed inside the structure. The contribution of each source is determined in such a way that the acoustic field radiated by these sources verifies the same boundary conditions on the structure. The number of unknowns in the problem is no longer directly linked to the number of mesh points on the structure, as with boundary elements methods, but to the number of equivalent sources employed in the model. The equivalent source method is therefore of major interest if the acoustic radiation of the structure can be approximated with a sufficiently low number of sources. This paper proposes its application when the equivalent source is a sphere. In this case, the number of unknowns is equal to the number of modes. In contrast to the one-point multipole, the sphere has a surface surrounding a closed volume to express the boundary conditions. Although sphere/multipole equivalence has been demonstrated, the surface of the sphere allows normalization of the functions used, leading to stabilization of the system to be resolved. First, the main acoustic radiation characteristics of a sphere and of the linear system verified by the modal coefficients of an equivalent sphere are presented. The different parameters of the model are then studied: position and radius of the equivalent sphere, truncation of the series, and influence of the spatial sampling (mesh). In the same vein, a second approach is presented. It consists of making each point of the structure correspond to a point of the sphere, and the vibrating field at the surface of the sphere is deduced from that of the structure by simple geometric projection. Results can be obtained very quickly as no matrix inversion is required. The accuracy of the results depends on the distance between the sphere and the structure. Finally, an experimental validation that uses both methods is presented and shows interesting results when the structure is closed, and when its shape is not too far removed from a sphere.

Journal Article↗
PubMed1999

Changing a hydrophobic heat and moisture exchanger after 48 hours rather than 24 hours: a clinical and microbiological evaluation.

OBJECTIVE: Complications following ventilation with dry and cold gases may be prevented by the use of artificial noses or heat and moisture exchangers, which are a solution to both the problems of humidification and heat preservation. The aim of the present study was to determine whether changing hydrophobic heat and moisture exchangers (HMEs) every 48 h rather than 24 h would affect their efficacy to preserve the heat and moisture of inspiratory gases. The impact of a prolonged use of the HME on its microbial colonization was also assessed. DESIGN: Prospective observational study. SETTING: ICU of a university hospital. PATIENTS: Twelve patients requiring controlled mechanical ventilation for more than 2 days were evaluated. INTERVENTIONS: The patients were ventilated with a heat and moisture exchanger (HME) (Maxipleat Filter, Europe Medical, France). The hydrophobic HME was placed between the Y-piece and the connecting tube and changed after 48 h of continuous use. Temperature (degree C), relative humidity (%) and absolute humidity (mgH2O/l) were obtained using the capacitive sensor principle. Bacterial colonization (tracheal secretions and ventilator side of the HME) were obtained on days 1 and 2. MEASUREMENTS AND RESULTS: After 48 h of ventilation with the same HME, tracheal tube occlusion was never observed. Using the same hydrophobic HME for 48 h rather than 24 h did not affect its technical performance: temperature at 24 h: 32.5 +/- 1.3 degrees C, at 48 h: 32.7 +/- 1.8 degrees C; relative humidity (RH) at 24 h: 99.0 +/- 1.4%, at 48 h: 99.0 +/- 1.4%; absolute humidity (AH) at 24 h: 34.0 +/- 2.4 mgH2O/l, at 48 h: 34.4 +/- 3.5 mgH2O/l. Peak and mean airway pressures did not change over the 48-h study period, with identical tidal and minute volumes in the study patients. Total respiratory heat losses were not modified during the 48-h study period (at 24 h: 152 +/- 47 cal/min, at 48 h: 149 +/- 65 cal/min). Evaporative and convective heat losses were not modified either. On day 1, eight patients had positive cultures of their tracheal secretions at a colony count of 10(3) or higher cfu/ml. After 48 h of use of the same HME, only six patients had a positive culture of their tracheal secretions. Cultures from the ventilator sides of the HMEs were all sterile (12/12) after 48 h of use. CONCLUSIONS: Changing the hydrophobic HME after 48 h rather than 24 h did not affect its technical performance in terms of heat and water preservation of ventilatory gases. There is also some indirect evidence of very little, if any, change in HME resistance. No bacterial colonization of the ventilator sides of the HMEs was observed after 48 h of use. However, other large clinical trials should be undertaken to confirm the safety of extending the time between HME changes.

Adult↗
PubMed1998

Heterogeneity of mesothelioma cell lines as defined by altered genomic structure and expression of the NF2 gene.

Germ-line mutations in the neurofibromatosis 2 (NF2) gene cause a susceptibility to the development of schwannoma and meningioma, 2 mostly benign tumors of neural crest origin. Bi-allelic inactivation of this gene has been observed in sporadic schwannomas and meningiomas. The NF2 gene may also be somatically inactivated in human malignant mesotheliomas (HMMs). Surprisingly, patients with an NF2 germ-line mutation have not been reported to be at an increased risk for this highly invasive tumor of mesodermal origin. To investigate in HMMs the silencing mechanism of the NF2 gene, we have analyzed its structure and expression in a series of 18 cell lines derived from HMMs. NF2 gene alterations were identified at a genomic level in 7 cell lines and were associated with a marked decrease in the concentration of the NF2 transcript. This decrease was also observed in 4 additional cell lines with no identified NF2 mutation. The 11 cell lines presented evidence suggesting deletion of one NF2 allele. None of these enabled the detection of normal or truncated forms of the NF2 protein by immunoprecipitational immunoblot analyses. In the 7 remaining cell lines, NF2 mRNA and NF2 protein were easily detectable. Among the latter, 4 lines were heterozygous for several chromosome 22 microsatellite loci, suggesting the presence of 2 NF2 alleles. Taken together, our data indicate that silencing of the NF2 gene is restricted to a subset of mesothelioma cell lines. The availability of established cell lines with different characterized NF2 status provides a powerful tool to explore the mechanism by which the NF2 protein exerts its tumor suppressive activity.

Alleles↗
PubMed1998

Germline mutation profile of the VHL gene in von Hippel-Lindau disease and in sporadic hemangioblastoma.

von Hippel-Lindau (VHL) disease is a dominantly inherited disorder predisposing those afflicted to hemangioblastomas of the central nervous system and the retina, renal cell carcinomas, pheochromocytomas, and pancreatic tumors. The disease has been associated with mutations of the VHL gene. The screening of 92 unrelated patients with VHL disease for point mutations in this gene revealed 61 DNA variants. In addition, a search for EcoR1 rearrangements revealed germline anomalies in 5 patients. The 61 variants could be subdivided in 20 mutations predicted to alter the open reading frame (8 nonsense mutations, 8 frame shift mutations, and 4 mutations in consensus splicing sites) and 43 DNA sequence variants of a priori unknown biological consequence (4 in-frame insertions or deletions, 36 missense mutations, and 3 apparently silent variations). The 3' end of the coding sequence of the VHL gene, which encodes the Elongin binding domain was the site of 5 of 20 truncating mutations (25%) and of 18 of 41 DNA variants (44%) causing uncertain functional impairment. A similar screening in 18 patients with sporadic hemangioblastoma revealed 2 missense DNA variants. In order to corroborate this latter observation, a systematic screening for germline alteration of the VHL gene might be performed in a larger series of sporadic hemangioblastoma. If this preliminary result is confirmed, more than 10% of sporadic hemangioblastoma might be related to a mild VHL disease, thus a follow-up program similar to that recommended in cases of VHL disease should probably be discussed in the corresponding families.

Adult↗
PubMed1998

Comparing two heat and moisture exchangers, one hydrophobic and one hygroscopic, on humidifying efficacy and the rate of nosocomial pneumonia.

OBJECTIVE: Many heat and moisture exchangers with filter (HMEF) have been developed. In-house data from companies provide some information about their performances; unfortunately, to our knowledge, no comparative evaluation in clinical conditions has been undertaken of these newer products. The aim of this study was to compare the efficiency of two HMEFs, one hydrophobic and one hygroscopic, on humidifying capacity and the rate of bronchial colonization and ventilator-associated pneumonia in ICU patients. DESIGN: Prospective, randomized study. SETTING: ICU of a university hospital. PATIENTS: All patients who required mechanical ventilation for > or = 24 h during the study period. INTERVENTIONS: On admission to the ICU, patients were randomly assigned to one of two groups. In one group, the patients were ventilated with a hygroscopic device (Humid-Vent Filter Light HMEF; Gibeck; Upplands Vaesby, Sweden). The condensation surface was made of paper (Microwell) impregnated with CaCl2. The filter membrane was made of polypropylene. In the other group, the patients were ventilated with a hydrophobic device (Pall BB100 HMEF). The condensation surface was made of a hydrophobic resin with a hydrophylic layer. The filter membrane was made of ceramic fibers. In both groups, HMEFs were changed daily. MEASUREMENTS AND RESULTS: Both groups of patients were similar for the tested characteristics, including parameters of mechanical ventilation. Sixty-six patients were ventilated for 11.7+/-11 days with the Humid-Vent Filter Light HMEF and 70 patients for 12.2+/-12 days with the Pall BB 100. Patients ventilated with the Humid-Vent Filter Light underwent 6.0+/-3.0 tracheal aspirations and 1.7+/-2.0 instillations per day, and those with the Pall BB 100, 6.0+/-3.0 and 1.6+/-2.0 per day, respectively (not significant [NS]). Abundance of tracheal secretions, presence of blood, and viscosity, evaluated by semiquantitative scales, were similar in both groups. No difference in the rate of atelectasis was observed between the two groups (7.5% and 7.1%, NS). One episode of tracheal tube occlusion was observed with the Humid-Vent Filter Light HMEF, and one with the other HMEF (NS). One patient in each group (NS) was switched to an active heated humidifier because of very tenacious bronchial secretions despite repeated instillations. Tracheal colonization was observed at a rate of 67% with the Humid-Vent Filter Light and 58% with the Pall BB 100 (NS). A small, but NS difference was observed in the rate of ventilator-associated pneumonia: Humid-Vent Filter Light, 32% (27.1 per 1000 ventilator days); and Pall BB 100, 37% (30.4 per 1000 ventilator days). Bacteria responsible for tracheal colonization and pneumonia were similar in both groups. Three patients in each group died from their nosocomial pneumonia. CONCLUSION: Despite differences in their components, the two HMEFs tested achieved similar performances in terms of humidification and heating of inspired gases. Only one episode of endotracheal tube occlusion was detected and very few patients (one in each group) had to be switched to an active heated humidifier. No difference was observed either in the rate of tracheal colonization or of ventilator-associated pneumonia. These data show that the hygroscopic HME (Humid-Vent Filter Light) and the hydrophobic HME (Pall BB 100) are suited for use in ICU patients.

Adult↗
PubMed1997

[Familial adenomatous polyposis coli in the Czech population. I. Detection of an additional 3 mutations out of a total of 7 in exon 15 of the APC gene].

BACKGROUND: Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease characterized by multiple adenomatous polyps in the colon which progress to carcinoma. FAP is caused by germ-line mutation of the tumor-suppressor adenomatous polyposis coli (APC) gene, the structure and coding sequence of which have been known from 1991. The diagnosis of FAP has classically been based on the detection of multiple colorectal adenomas, often after carcinoma development. Presymptomatic genetic testing for the presence of an allele carrying the FAP mutation is now possible using a variety of techniques. METHODS AND RESULTS: The present paper is the first part of an analysis of 37 different Czech families with 83 members affected by FAP. Our goal is to identify the mutation characteristic for each family for early diagnosis of FAP. We screened clinically manifest representatives of nine families for mutations in exon 15 of the APC gene. First, we searched for the mutation hot spots (codons 1061 and 1309, respectively) and later for the entire exon 15. Denatured gradient gel electrophoresis (DGGE) of amplified regions ov exon 15 has been used to identify DNA sequence variations followed by sequencing verification. In seven patients, seven different mutations in exon 15 of APC gene, four deletion mutants (5-base deletions in codons 1061 and 1309, 1-base deletion in codons 759 and 7-base deletion combined with a 2-base insertion in codon 712), one insertion mutation (1-base/A/insertion in codon 1554) and two point mutations (C to T and C to A substitutions in codons 737 and 935, respectively, in both cases leading to formation of stop codons) have been found. CONCLUSIONS: From seven different mutations found, 4 mutations have been previously described (mutations in codons 935, 1061, 1309 and 1554), 3 mutations in the APC gene are described here for the first time, namely the mutations in codons 712, 759 and 767.

Adenomatous Polyposis Coli↗
PubMed1997

Patterns of cytokine evolution (tumor necrosis factor-alpha and interleukin-6) after septic shock, hemorrhagic shock, and severe trauma.

OBJECTIVE: To compare the patterns of evolution of two proinflammatory cytokines (tumor necrosis factor [TNF]-alpha and interleukin-6 [IL-6]) in two major clinical entities associated with systemic inflammatory response: septic shock and multiple trauma (with and without hemorrhagic shock). DESIGN: Prospective study of two cohorts of patients. SETTING: Critical care unit and Emergency Center of a university hospital. PATIENTS: Twenty-five nontrauma patients with septic shock and 60 multiple trauma patients (of whom eight patients were resuscitated from hemorrhagic shock). INTERVENTIONS: Serial blood samples were collected in each patient for determination of serum cytokine concentrations. Samples were obtained over 7 days in septic shock patients and 11 days in trauma patients. Standard resuscitation techniques were used in each patient. Clinical and laboratory data were prospectively collected. MEASUREMENTS AND MAIN RESULTS: High concentrations of circulating TNF-alpha and IL-6 were found in patients with septic shock. High IL-6 concentrations, but normal TNF-alpha concentrations were detected in trauma patients. At study entry, TNF-alpha concentrations were higher in nonsurvivor septic shock than in nonsurvivor trauma patients (42 +/- 7 vs 13 +/- 2 pg/mL; p < .001). During the whole study period, nonsurvivor septic shock patients maintained higher TNF-alpha concentrations than nonsurvivor trauma patients (p < .001). In survivors in both groups, normal values for TNF-alpha were detected during the whole study period. At study entry, IL-6 concentrations were significantly higher in nonsurvivor septic shock patients than in nonsurvivor trauma patients (15,627 +/- 4336 vs. 317 +/- 124 pg/mL; p < .0001). During the whole study period, much higher concentrations of IL-6 were detected in septic shock patients than in trauma patients (p < .0001). In survivors, at study entry, IL-6 concentrations were much higher in septic shock patients than in trauma patients (3947 +/- 1410 vs. 247 +/- 41 pg/mL; p < .001). Higher IL-6 concentrations were maintained throughout the study period in septic shock patients than in trauma patients (p < .001). In septic shock patients, changes in both TNF-alpha and IL-6 were correlated with outcome, higher values being found in patients likely to die. Neither TNF-alpha nor IL-6 values were of any significant value in predicting outcome of trauma patients. When septic shock patients were compared with traumatized patients resuscitated from hemorrhagic shock, the former had much higher concentrations of both TNF-alpha and IL-6 throughout the study period (p < .01 to p < .00001). Increased IL-6 values were an indicator of the development of a nosocomial infection in trauma patients. In five trauma patients who developed a nosocomial pneumonia during the study period, the IL-6 concentration was 433 +/- 385 pg/mL before the onset of pneumonia, then peaked at 3970 +/- 1478 pg/mL on day 7, and returned to baseline (219 +/- 58 pg/mL) on day 11. CONCLUSIONS: In septic shock patients, high amounts of circulating TNF-alpha and IL-6 are found and then correlate with fatal outcome. In trauma patients (even those patients resuscitated from hemorrhagic shock), much less increased concentrations of IL-6 are detected while normal TNF-alpha circulating concentrations are measured. In these patients, cytokine concentrations do not correlate with outcome. This finding suggests a much higher degree of activation of the immunoinflammatory cascade in septic shock than in multiple trauma patients. Increased IL-6 values are an indicator of the development of a nosocomial infection in trauma patients.

Adult↗
PubMed1996

Germline mutations in the Von Hippel-Lindau disease (VHL) gene in families from North America, Europe, and Japan.

Germline mutation analysis was performed in 469 VHL families from North America, Europe, and Japan. Germline mutations were identified in 300/469 (63%) of the families tested; 137 distinct intragenic germline mutations were detected. Most of the germline VHL mutations (124/137) occurred in 1-2 families; a few occured in four or more families. The common germline VHL mutations were: delPhe76, Asn78Ser, Arg161Stop, Arg167Gln, Arg167Trp, and Leu178Pro. In this large series, it was possible to compare the effects of identical germline mutations in different populations. Germline VHL mutations produced similar cancer phenotypes in Caucasian and Japanese VHL families. Germline VHL mutations were identified that produced three distinct cancer phenotypes: (1) renal carcinoma without pheochromocytoma, (2) renal carcinoma with pheochromocytoma, and (3) pheochromocytoma alone. The catalog of VHL germline mutations with phenotype information should be useful for diagnostic and prognostic studies of VHL and for studies of genotype-phenotype correlations in VHL.

Adrenal Gland Neoplasms↗
PubMed1996

Transvaginal ultrasound studies of vascular and morphological changes in uteri exposed to diethylstilbestrol in utero.

The aim of this prospective study was to establish complementary data of uteri exposed to diethylstilbestrol (DES) in utero for transvaginal analysis and vascularity changes during the menstrual cycle. A total of 28 women with DES-exposed uteri were compared with 60 non-exposed women. Transvaginal ultrasound and colour Doppler imaging were performed on days 5 and 22 of the menstrual cycle. Uteri were measured on sagittal and transverse scans. Uterine length, width, thickness and uterine cavity length and width were measured. Uterine volume and uterine cavity area were calculated. DES-exposed uterine volume was equal to 31.84 +/- 3.37 cm3. The cavity area of DES-exposed uterus was equal to 35.85 +/- 3.93 cm2. Cervix length of DES-exposed uterus was significantly smaller than that of non-exposed uterus. The uterine artery pulsatility index (PI) of DES-exposed uterus was significantly higher than that of normal uterus. Blood flow remained stable throughout the menstrual cycle. The PI of DES-exposed uterus remained stable during the menstrual cycle, as in non-exposed uterus, and it decreased during the luteal phase. This lack of modification in vascularity of DES-exposed uterus may explain miscarriages and obstetric complications such as intrauterine growth retardation or pre-eclampsia. The data may have implications for the assessment of reproductive status and the design of future studies on disorders of implantation in DES-exposed uterus.

Adult↗
PubMed1995

Familial adenomatous polyposis: desmoid tumours and lack of ophthalmic lesions (CHRPE) associated with APC mutations beyond codon 1444.

An earlier study has shown that FAP patients with mutations in codons 136-302 of the APC gene do not develop congenital hypertrophy of the retinal pigment epithelium (CHRPE), whereas those with mutations in codons 463-1387 regularly do. Here we present data on 36 patients from 20 families with mutations in codons 1445-1578. These patients lack CHRPE. Furthermore, with the exception of three prepubertal children all patients with mutations in codons 1445-1578 developed desmoid tumours. This relationship between certain extracolonic manifestations and site of the APC mutation points to a specific role of the APC protein in different tissues.

Adenomatous Polyposis Coli↗
PubMed1995

DNA-based presymptomatic diagnosis for the von Hippel-Lindau disease by linkage analysis.

Von Hippel-Lindau (VHL) disease is an autosomal dominantly inherited condition characterized by a predisposition to the development of haemangioblastoma, renal cell carcinoma and phaeochromocytoma. The gene which, when altered, causes the disease was cloned in 1993, and maps within a series of known polymorphic loci in the 3p25-p26 region. To optimize a DNA-based presymptomatic diagnosis, we have selected six highly informative microsatellite loci, closely linked to the VHL gene. Genotyping using a multiplex-PCR approach was performed in 26 affected families including 99 asymptomatic relatives born from an affected parent. Ninety-six subjects were informative with one or more markers, 76 being informative with markers on both sides of the gene. Combination of age-related and DNA-based risk information improved the accuracy of risk assessment for 90 at-risk patients (91%) and allowed attribution of risk with a confidence limit higher than 0.98 in 79 cases (88%).

Adolescent↗
PubMed1991

Rapid and sensitive discriminating determination of acetylcholinesterase activity in amniotic fluid with a choline sensor.

A simple method for the separate determination of acetylcholinesterase and butyrylcholinesterase activities in amniotic fluid is reported. This determination is performed with an enzyme electrode involving an immobilized choline oxidase membrane associated with the amperometric detection of hydrogen peroxide. Acetylcholine or butyrylcholine, in the presence of samples containing acetylcholinesterase or butyrylcholinesterase are specifically hydrolyzed, the formation of choline being detected vs time by the sensor with no need for a selective inhibitor. The dynamic linear ranges for acetylcholinesterase and butyrylcholinesterase are respectively 100 microU to 10 mU and 30 microU to 3 mU per ml sample.

Acetylcholine↗