Biomedical subjects

O Leroy

Publications and source records attributed to O Leroy.

At least 19 recordsLinked to original sources

PubMed2001

[Severe community-acquired pneumonia].

Community-acquired pneumonia is severe when hospitalisation is required. The diagnosis is based on pulmonary involvement (chest radiography) associated with vital signs abnormalities (mental status, temperature, blood pressure and ventilatory rate) or immunosuppression (neoplastic diseases). No specific causative pathogen could be incriminated. S. pneumoniae is the main causative pathogen. Prognosis-related factors are numerous. Among them, the effectiveness of the initial antimicrobial therapy appears as the main factor directly related to the medical intervention. First-line antimicrobial therapy, instituted as soon as possible, is empirical and must, always, be effective against S. pneumoniae. For pneumonia requiring admission into ICU, a wider antimicrobial spectrum based on antimicrobial combination is used. Mortality rates varying from 3 to 30% could be early predicted by specific prognostic indices.

Anti-Bacterial Agents↗

PubMed2001

Tolerability and immunogenicity of an 11-valent pneumococcal conjugate vaccine in adults.

We studied the safety and immunogenicity in healthy adults of an 11-valent pneumococcal conjugate vaccine. Capsular polysaccharides (PS) of serotypes 1, 4, 5, 7F, 9V, 19F and 23F were conjugated to tetanus toxoid, and of serotypes 3, 6B, 14 and 18C to diphtheria toxoid. Ten subjects received the conjugate vaccine with and the other ten subjects without aluminium hydroxide adjuvant. The reference vaccine was a marketed 23-valent PS vaccine. Safety data were recorded over 5 days after the immunisation. IgG antibody concentrations, avidity and subclass distribution were measured by EIA. The conjugate without aluminium induced more local adverse effects than the conjugate with aluminium or PS vaccine. All vaccines evoked significant antibody increases to all vaccine specific antigens. Both conjugate vaccines induced antibodies mainly of IgG(2) subclass, and adjuvanted conjugate vaccine induced IgG antibodies with increased avidity. This first administration, to man, of a mixed protein carrier 11-valent pneumococcal conjugate vaccine demonstrated its ability to induce an immune response without significant adverse effects, enabling further study on its use in paediatric populations.

Adjuvants, Immunologic↗

PubMed2001

Activation of cell-mediated immunity following immunization with pneumococcal conjugate or polysaccharide vaccine.

The immunogenicity of pneumococcal polysaccharide (PS) vaccines can be improved by conjugating PS to a polypeptide carrier that alters the immune response from T-cell independent to T-cell dependent. In order to study the influence of PS or protein antigens as inducers of cell-mediated responses, 30 adults were immunized with a 23-valent pneumococcal PS vaccine (PS-group) or an 11-valent, tetanus and diphtheria mixed carrier conjugate vaccine with (adjuvant group) or without aluminium adjuvant (nonadjuvant group). Cell-mediated responses were analyzed on days 0, 14 and 28 after vaccination by measuring lymphocyte proliferation and production of interferon (IFN)-gamma (Th1 marker) or interleukin (IL)-4 and IL-5 (Th2 markers) cytokines after in vitro stimulation with the PS and protein components of the vaccines. Tetanus and diphtheria proteins were the main inducers of lymphocyte proliferative and cytokine responses. Conjugate vaccines induced increased proliferative responses to the tetanus or diphtheria protein, but not to the PS components. In the PS-group, a lymphocyte proliferative response to protein antigens was not observed. The number of antigen-specific and nonspecific IFN-gamma-secreting cells detected by ELISPOT tended to increase in all three groups in response to protein or to PS antigen. No major differences were detected in the number of IL-4-secreting cells measured 14 and 28 days after vaccination. The conjugate vaccine with adjuvant was associated with Th2 type of activation indicated by an enhanced IL-5 secretion in response to the tetanus and diphtheria protein antigens.

Adjuvants, Immunologic↗

PubMed2001

Tolerability and immunogenicity of an eleven-valent pneumococcal conjugate vaccine in healthy toddlers.

BACKGROUND: A need to increase the serotype coverage of pneumococcal conjugate vaccines exists. The use of a single carrier protein may cause overload of the carrier and decrease the immune response by not providing sufficient carrier-specific T helper cell support. A vaccine composed of a mixture of tetanus- and diphtheria-conjugated polysaccharides (PS) is a potential solution to this issue. OBJECTIVES: The aim of this study was to assess the tolerability and immunogenicity in healthy toddlers of an 11-valent pneumococcal conjugate vaccine that uses both tetanus and diphtheria toxoids as carriers. We explored the effect of an aluminum adjuvant on safety and immunogenicity by comparing the vaccine with and without adjuvant. METHODS: Twenty Finnish and 23 Israeli toddlers received the conjugate vaccine with or without aluminum adjuvant. Safety data were recorded for 5 days after vaccination. Sera were obtained before and 28 days after the immunization. IgG antibodies to the 11 vaccine-type PSs were determined by enzyme immunoassay. RESULTS: No serious adverse events occurred. The formulation with the adjuvant tended to induce fewer local but more systemic reactions than the non-adjuvant-containing formulation. Both vaccine formulations induced significant IgG increases for the vaccine-specific PSs. Types 3 and 7F were the most immunogenic; antibodies reached a concentration of 1 microg/ml in all individuals. Conjugates of types 6B, 14 and 23F were the weakest immunogens; antibodies reached the concentration of 1 microg/ml in 36, 27 and 32% of the individuals in the nonadjuvant group and in 53, 38 and 53% in the adjuvant group, respectively. CONCLUSIONS: An 11-valent mixed carrier pneumococcal conjugate vaccine is safe and immunogenic in toddlers. The use of an adjuvant do not seem to offer any significant benefit.

Adjuvants, Immunologic↗

PubMed2001

Thin coating characterization by Rayleigh waves: an analytical model based on normal-mode theory.

The acousto-optic technique to evaluate coated substrates, presented by Devolder et al. [Appl. Phys. Lett. 68, 1732 (1996)], uses the phase dependence of the reflected beam on the coating parameters. In this theoretical paper, a fully analytical model, based on normal-mode theory, is applied to this problem. It gives a transparent expression for the phase shift between the reflected and the incident field due to the presence of thin coatings (coating thickness much smaller than wavelength sound). The known numerical results from Fourier simulations, i.e. the phase dependency on the coating parameters and the advantages of using higher frequencies and wider beams, are reproduced. However, thanks to the analytical nature of the new theory, additional results are obtained. The calculation time is reduced by two orders of magnitude, which is important for the inverse problem. A technique for absolute thickness measurements is proposed. Measuring more to the right of the second reflected maximum increases the phase sensitivity. The versatility of the normal-mode approach is illustrated by applying it to other nondestructive testing (NDT) applications, such as hardness determination and adhesion testing, which are briefly discussed.

Journal Article↗

PubMed2000

Salivary anti-capsular antibodies in infants and children immunised with Streptococcus pneumoniae capsular polysaccharides conjugated to diphtheria or tetanus toxoid.

Saliva samples of infants and children immunised with pneumococcal vaccines were analysed for anti-polysaccharide (PS) antibodies against the Streptococcus pneumoniae (Pnc) vaccine serotypes 6B, 14, 19F, and 23F. The children received Pnc conjugate vaccine (1, 3, or 10 micrograms of PSs conjugated to diphtheria or tetanus toxoid) or placebo at 2, 4, and 6 months. At 7 months of age salivary PS antibodies were detected rarely. All children received Pnc conjugate or PS vaccine at 14 months of age. At 15 months, both IgA and IgG anti-Pnc PS were found, anti-19F and anti-14 antibodies occurring most frequently and in the highest concentrations. IgA was in the secretory form and predominantly IgA1. A negative dose dependency was observed in IgA anti-19F response. In general, no clear differences in salivary antibody responses were found between the children primed with conjugate vaccine in infancy and those who received their first Pnc vaccine at 14 months of age, suggesting that priming with Pnc conjugate vaccines does not lead to remarkable mucosal memory responses.

Antibodies, Bacterial↗

PubMed2000

On the polarization of light diffracted by ultrasound

If light is diffracted by ultrasound in an isotropic medium with acoustically induced birefringence, the state of polarization is modified in each order of diffraction with respect to the initial state of polarization of the incident light wave. In the present paper, some polarization effects are discussed in the case of normal light incidence. In general a rotation of the main polarization plane occurs, together with a change of the ellipticity. However, while the former effect always takes place, the latter only occurs in the case of ultrasonic light diffraction of the intermediate type. Some experimental measurements are included in case of argon laser light being diffracted by an ultrasonic wave propagating in fused silica (SiO2).

Journal Article↗

PubMed2000

Collinear acousto-optic diffraction using two nearby sound frequencies

Collinear acousto-optic spectrometers with sound consisting of one frequency have a spectral transfer function with many good characteristics, such as a narrow bandwidth, ... the side lobes, however, are rather high. To reduce these side lobes, one can try to apodize the sound in the acousto-optic cell by using a sound wave consisting out of two frequencies. At certain times, this produces a more smoothened sound field in the cell than in the one-frequency case. The resulting transfer function will contain lower side lobes. Also, the influence of all the sound field parameters--the amplitude, frequency difference, and time--on the transmission function is studied. Out of these results, better-performing collinear spectrometers can be designed.

Journal Article↗

PubMed2000

Schlieren photography study of energy absorption by uric acid nuclei.

Previous studies using microfocus x-ray radiography on concentric laminated uric acid calculi following in vitro extracorporeal shock-wave lithotripsy (ESWL) has demonstrated the enlargement of the matrix layers. The Schlieren technique was used to verify the hypothesis that the incident energy would be concentrated in the matrix layers by total internal reflection. Because of the rough surface of the stone, the ultrasonic beam (4 MHz) was incident at various angles. At the critical Rayleigh angle (45.9 degrees +/- 0.5 degrees ), the reflected beam consisted of a spectacularly reflected lobe and a reradiated leaky Rayleigh wave. Different critical Lamb angles, theta(L), of 30.8 degrees, 38.1 degrees and 50.8 degrees (experimental uncertainty 0.5 degrees ) were also determined. Depending on the angle of incidence on the stone surface, a Rayleigh wave can be produced and/or one or more layers, as a whole, are set into vibration (Lamb excitation), with the result that shell-like fragments consisting of one or more layers, break off the stones at sites of weaker bonding, as has been noted in previous in vitro lithotripsy experiments by our group.

Absorption↗

PubMed2000

Extension of the mode method for viscoelastic media and focused ultrasonic beams.

In the present study viscoelasticity is introduced in the mode model and the orthogonality condition is adapted for viscous media. The expansion of convergent acoustic Gaussian beams in terms of radiation modes for viscoelastic media is studied as well. The effects on the reflected and transmitted profiles of acoustic beams incident from an ideal liquid onto a viscoelastic plate are shown and physically explained. It is shown that focusing the incident beam can suppress divergence effects and gives the possibility to measure shear wave attenuation coefficients.

Acoustics↗

PubMed2000

Bounded beam interaction with thin inclusions. Characterization by phase differences at Rayleigh angle incidence.

A theoretical study of the reflection of a bounded Gaussian ultrasonic beam, incident onto a rectangular inclusion located near a fluid/solid half-space interface, is presented. The thickness of the inclusion is assumed to be much smaller than the ultrasonic wavelength in the solid. It is shown that, at critical Rayleigh angle incidence, the phase in the point of maximum amplitude of the shifted reflected lobe is very sensitive to dimension variations of the inclusion, and thus useful for inclusion characterization. The modelization of the problem is based on mode theory.

Acoustics↗

PubMed2000

Predisposing factors for nosocomial pneumonia in patients receiving mechanical ventilation and requiring tracheotomy.

STUDY OBJECTIVES: To assess the incidence of nosocomial pneumonia (NP) after tracheotomy in an ICU population and to determine NP risk factors during the ICU stay, particularly on the day of tracheotomy. DESIGN: A retrospective study using prospectively collected data. SETTING: A 16-bed multidisciplinary ICU. PATIENTS: One hundred thirty-five patients requiring tracheotomy for mechanical ventilation (MV) weaning. RESULTS: The mean (+/- SD) duration of MV before tracheotomy was 17.8 +/-13.4 days. Thirty-seven cases of NP occurred in 35 patients (25.9%), 8.7+/-7.3 days after the tracheotomy procedure. NP cases were classified as early NP (n = 19) if they occurred within 5 days after the procedure (mean, 2.7+/-1.1 days), and as late NP (n = 18) if they occurred beyond the fifth day (mean, 14.4+/-6.1 days). Multivariate analysis identified the following three independent factors associated with early NP: the presence of positive endotracheal aspirates (EAs) with pathogen levels of > or =10(5) cfu/mL (p = 0.0001); hyperthermia (temperature, > or =38.3 degrees C; p = 0.002) on the day of tracheotomy; and the continuation of sedation beyond 24 h after the tracheotomy (p = 0. 0001). Accountable pathogens of early NP were present in EA on the day of tracheotomy (p = 0.001). Cases of late NP were significantly associated with the duration of sedation before the procedure (p = 0. 002) and with hyperthermia (temperature, > or =38.3 degrees C) on the day of tracheotomy (p = 0.0005). The ICU admitting diagnosis, previous NP, duration of administration of antimicrobial agents and MV before tracheotomy, indication for tracheotomy, PO(2)/fraction of inspired oxygen ratio, and use of steroids on the day of the procedure were not associated with the occurrence of NP. The mortality rate of our population was 33.3%, and NP increased this percentage to 54.3%. CONCLUSIONS: Our results could suggest that tracheotomy should be delayed in mechanically ventilated patients with bronchial colonization and hyperthermia, when sedation cannot be discontinued after the procedure, to prevent occurrence of early NP.

Adult↗

PubMed1999

Dose dependency of antibody response in infants and children to pneumococcal polysaccharides conjugated to tetanus toxoid.

Three injections of tetravalent pneumococcal polysaccharide-tetanus toxoid conjugate vaccine (PncT) were given to infants at 2, 4 and 6 months of age simultaneously with diphtheria-tetanus-pertussis and Haemophilus influenzae type b-tetanus toxoid conjugate vaccines. Three doses (1, 3 or 10 microg) of polysaccharides were used. Children were boosted with unconjugated polysaccharide vaccine at 14 months of age. No dose dependency was seen after primary immunization. However, booster response to three vaccine serotypes was highest in the group primed with the lowest dose of conjugate vaccine. As the magnitude of the response to booster may be related to the number of polysaccharide-specific memory B cells, we hypothesize that the 10 microg dose of the tetravalent conjugate vaccine is too high for optimal induction of immunologic memory.

Antibodies, Bacterial↗

PubMed1999

Epidemiological features and prognosis of severe community-acquired pneumococcal pneumonia.

OBJECTIVE: To describe risk factors of severe pneumococcal community-acquired pneumonia and to study variables influencing outcome. DESIGN: Retrospective (1987-1992) and prospective (1993-1995) study. SETTING: Three participating ICUs from primary care hospitals. PATIENTS: Five hundred and five patients (mean age: 63 +/- 17 years) with severe community-acquired pneumonia (CAP). Three groups of patients were defined: pneumococcal CAP (group 1), CAP with microbial diagnosis other than Streptococcus pneumoniae (group 2), CAP from group 2 and CAP without microbial diagnosis (group 3). MEASUREMENTS AND RESULTS: Admission data and data on the disease's course were recorded. The mean Simplified Acute Physiologic Score (SAPS) was 12.5 +/- 5.4. On admission 288 (57 %) patients were mechanically ventilated (mv) and 82 (16.2 %) required inotropic support. A microbial diagnosis was established for 309 (61.2%) patients. S. pneumoniae was isolated in 137 (27.1%) patients. Severe pneumococcal CAP was independently associated with male sex (p = 0.01), lack of antibiotics use before admission (p = 0.0001), non-aspiration pneumonia (p = 0.01) and septic shock (p = 0.0001). The overall mortality rate was 27.5 % (29.2 % in group 1). In patients with severe pneumococcal CAP, multivariate analysis showed that leukopenia less than 3,500/mm3 (p = 0.0004), age over 65 years (p = 0.01), septic shock (p = 0.01), sepsis related complications (p = 0.0001), ICU complications (p = 0.001) and inadequacy of antimicrobial therapy (p = 0.002) worsened the prognosis. CONCLUSIONS: Few features facilitate the identification of pneumococcal CAP on ICU admission. The prognosis is mostly related to severity of illness (leukopenia, septic shock) while comorbidities do not seem to influence outcome. Sepsis-related disorders, ICU complications and adequate antimicrobial chemotherapy are the major variables affecting the outcome during an ICU stay.

APACHE↗

PubMed1999

Effect of hospital-acquired ventilator-associated pneumonia on mortality of severe community-acquired pneumonia.

PURPOSE: The purpose of this article is to evaluate, using two pairwise case-control studies, attributable mortality linked to hospital-acquired ventilator-associated pneumonia (HA-VAP) complicating the intensive care unit (ICU) stay of patients exhibiting severe community-acquired pneumonia (CAP). MATERIALS AND METHODS: Over an 11-year period, 498 patients with severe CAP were collected. Among them, 43 exhibited HA-VAP. In a first case-control study, these patients were matched with control on the basis of six confounding variables known to be general ICU prognosis factors. In a second case-control study, six variables specifically linked to CAP prognosis were used for matching. RESULTS: In the two case-control studies, each case patient was matched with one control patient. In the first analysis, success of matching was achieved in 198 of 258 (77%) variables used for matching. In the second analysis, matching was successful for 242 of 258 (94%) confounding variables used. Eighteen patients died, compared with, respectively, 6 (P = .003) and 7 (P = .01) controls. Attributable mortality of HA-VAP was similar in the two pairwise analyses, respectively, 28% (risk ratio = 3.0; 95% confidence interval, 1.32 to 6.82) and 26% (risk ratio = 2.57; 95% confidence interval, 1.2 to 5.52). CONCLUSION: When confounding factors were controlled, HA-VAP appeared to increase mortality of severe CAP requiring ICU admission.

Aged↗

PubMed1999

Pneumococcal conjugate vaccination in toddlers: mucosal antibody response measured as circulating antibody-secreting cells and as salivary antibodies.

BACKGROUND: Our previous studies have shown an antibody-secreting cell (ASC) response to pneumococcal vaccines in adults and suggested that a high IgA ASC response is an indicator of a secretory IgA response in saliva. We believe that the mucosal immune response is potentially an important characteristic of the pneumococcal vaccines and should thus be measured when the new pneumococcal conjugate vaccines are evaluated. OBJECTIVES: To study mucosal and serum antibody responses to pneumococcal conjugate vaccines in toddlers. METHODS: Each investigational vaccine, containing either 3 or 10 microg of pneumococcal PS serotypes 6B, 14, 19F and 23F conjugated to either diphtheria toxoid (PncD) or tetanus protein (PncT), was administered to 10 children (a total of 40 children). The ASC response was measured on Day 7 after immunization by enzyme-linked immunospot assay, and the salivary and serum antibodies were measured before and 7 and 28 days after the immunization by enzyme immunoassay. RESULTS: The vaccines studied induced ASC responses to the pneumococcal polysaccharides (PS) in all children vaccinated. The ASC responses to the PS components of the vaccine (the geometric mean number of ASCs varying from 120 to 160 ASC/10(6) cells) were lower than those seen earlier in adults after conjugate vaccine (240 to 2015 ASC/10(6) cells), but comparable with those seen earlier in adults after pneumococcal PS vaccine (113 to 136 ASC/10(6) cells). The ASC response was clearly dominated by IgA-secreting cells. Salivary IgA responses were detected in 35% of the children, but IgG was rarely detected in saliva. A positive correlation was demonstrated between the number of IgA ASCs and salivary IgA concentration (r = 0.70, P = 0.01), suggesting that a high number of IgA ASCs after parenteral immunization is an indicator of a secretory IgA response in saliva. On Day 28 after immunization increased serum concentrations of IgG were detected in most vaccinees (75 to 95%, depending on the serotype). CONCLUSIONS: Both mucosal and systemic antibody responses were induced by PncD and PncT vaccines in toddlers.

Antibodies, Bacterial↗

PubMed1999

Community-acquired pneumonia in the intensive care unit: epidemiological and prognosis data in older people.

OBJECTIVES: To compare epidemiological data, etiology, and prognosis of severe community-acquired pneumonia (CAP) in the intensive care unit (ICU) according to age (< or > or = 65 years) and to determine prognostic factors of CAP in older people. DESIGN: A retrospective (1987-1992) and prospective (1993-95) multicenter study. SETTING: Six ICUs in the north of France. PATIENTS: Five hundred five patients admitted to an ICU for severe CAP. MEASUREMENTS: Patient characteristics were compared with regard to age. Prognosis of CAP in older patients was studied by stepwise discriminant analysis. RESULTS: Two hundred seventy-eight patients (55%) were aged 65 years or older. Comparison of epidemiological data between older and younger patients revealed a higher prevalence of women (38% vs 29%), more severe underlying comorbidities (anticipated death within 5 years: 59% vs 26%), and more frequent chronic respiratory insufficiency (48% vs 33%) in the older patients. In this study group, 224 organisms were isolated from 172 patients (62%); those identified most frequently were Gram-negative bacilli (34%), S. pneumoniae (32%), and Staphylococcus sp. (19%). Compared with younger patients, no significant differences in bacteriological data were observed. However, crude and attributable mortality rates were significantly higher in the older patients (33% vs 21% and 30% vs 19%, respectively). Prognosis analysis identified four independent predictors of mortality in the older patients: initial septic shock (relative risk (RR) = 3), sepsis-related complications (RR = 4.3), hospital-acquired lower respiratory tract superinfections (RR = 2), and nonspecific pneumonia-related complications (RR = 2.8). CONCLUSION: The bacterial etiology provides some approaches to empirical therapy for older patients with severe community-acquired pneumonia. In addition, the inappropriateness of withholding intensive care for reasons of age alone is emphasized.

Age Factors↗

PubMed1999

Simplified prediction rule for prognosis of patients with severe community-acquired pneumonia in ICUs.

STUDY OBJECTIVES: To develop a simplified prognostic prediction rule for patients admitted to ICUs for severe community-acquired pneumonia (CAP). SETTING: Six ICUs in the north of France. PATIENTS: Five hundred five patients admitted to ICUs over a 9-year period (from 1987 to 1995) for severe CAP. INTERVENTIONS: Retrospective prognosis analysis and multivariate analysis using a credit scoring technique. MEASUREMENTS: The primary outcome measure was ICU mortality. RESULTS: Among the 505 patients, 472 were eligible for the prognosis study. The ICU mortality rate was 22.9%. Multivariate analysis identified, on the basis of the patient's medical history and initial examination on ICU admission, six independent predictors of mortality: age > or = 40 years, anticipated death within 5 years, nonaspiration pneumonia, chest radiograph involvement > 1 lobe, acute respiratory failure requiring mechanical ventilation, and septic shock. An initial risk score based on these factors classified patients into three risk classes of increasing mortality: 4% in class I, 25% in class II, and 60% in class III. Multivariate analysis of events occurring during ICU stay identified three independent predictors of mortality: hospital-acquired lower respiratory tract superinfections, nonspecific CAP-related complications, and sepsis-related complications. An adjustment risk score based on these factors was essential to accurately predict the final outcome of patients in the initial risk class II. CONCLUSIONS: As an aid to clinicians in stratifying the prognosis of patients with severe CAP, the simplified prediction rule used in this study could be useful for therapeutic decisions and appropriate care.

Community-Acquired Infections↗