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Biomedical subjects

P Blondeau

Publications and source records attributed to P Blondeau.

At least 19 recordsLinked to original sources
PubMed2006

Volatile organic compound (VOC) adsorption on material: influence of gas phase concentration, relative humidity and VOC type.

UNLABELLED: This paper presents the results of a factorial experiment design analysis to investigate volatile organic compounds (VOC) adsorption on a ceiling tile. The impacts of three factors, VOC gas phase concentration, relative humidity, and VOC type, as single parameters and as a combination, on adsorption have been investigated. Cyclohexane, toluene, ethyl acetate, isopropyl alcohol and methanol were the five VOCs used in this study. A factor significant level was determined through evaluating its F value and comparing it with the critical value of F distribution at 95% confidence level. It was found that: (i) neither the relative humidity and gas phase concentration nor any interaction effect between them had significant impacts on toluene adsorption on the ceiling tile; (ii) the adsorption isotherm appeared to be linear for the non-polar compounds and non-linear for the semi-polar and polar compounds; (iii) no significant impact of relative humidity on adsorption was observed for most VOC compounds except for methanol; and (iv) the ceiling tile had the highest adsorption capacity toward the polar compounds, followed by the aromatic compounds and aliphatic compounds. In addition, the statistical analysis regarding the experimental results of toluene as a single compound or as a part of a mixture showed that toluene adsorption capacity on the ceiling tile as a single compound was higher than as a part of a mixture. PRACTICAL IMPLICATIONS: Building materials and furnishings may act as source and sink of VOCs in the indoor environment. In this study, a factorial experiment design analysis technique was used to show the impact of three factors, VOC gas phase concentration, relative humidity, and VOC type, as single parameters and as a combination, on the adsorption process (sink effect). The aim was to better understand the interaction between these parameters and to verify the common assumptions made in the model development and measurement of indoor air quality.

Adsorption↗
PubMed2005

Relationship between outdoor and indoor air quality in eight French schools.

UNLABELLED: In the frame of the French national research program PRIMEQUAL (inter-ministry program for better air quality in urban environments), measurements of outdoor and indoor pollution have been carried out in eight schools in La Rochelle (France) and its suburbs. The buildings were naturally ventilated by opening the windows, or mechanically ventilated, and showed various air permeabilities. Ozone, nitrogen oxides (NO and NO(2)), and airborne particle (particle counts within 15 size intervals ranging from 0.3 to 15 mum) concentrations were continuously monitored indoors and outdoors for two 2-week periods. The indoor humidity, temperature, CO(2) concentration (an indicator of occupancy), window openings and building permeability were also measured. The temporal profiles of indoor and outdoor concentrations show ozone and nitrogen oxides behave differently: NO and NO(2) indoor/outdoor concentration ratios (I/O) were found to vary in a range from 0.5 to 1, and from 0.88 to 1, respectively, but no correlation with building permeability was observed. On the contrary, I/O ratios of ozone vary in a range from 0 to 0.45 and seem to be strongly influenced by the building air-tightness: the more airtight the building envelope, the lower the ratio. Occupancy, through re-suspension of previously deposited particles and possible particle generation, strongly influences the indoor concentration level of airborne particles. However, this influence decreases with particle size, reflecting the way deposition velocities vary as a function of size. The influence of particle size on deposition and penetration across the building envelope is also discussed by analyzing the I/O ratios measured when the buildings were unoccupied, by comparing the indoor concentrations measured when the buildings were occupied and when they were not (O/U ratios), and by referring to previously published studies focussing on this topic. Except one case, I/O were found to vary in the range from 0.03 to 1.79. All O/U are greater than one and increase up to 100 with particle size. PRACTICAL IMPLICATIONS: Assessing children's total exposure requires the knowledge of outdoor and indoor air contaminant concentrations. The study presented here provides data on compared outdoor and indoor concentration levels in school buildings, as well as information on the parameters influencing the relationship between outdoor and indoor air quality. It may be used as a basis for estimating indoor concentrations from outdoor concentrations data, or as a first step in designing buildings sheltering children against atmospheric pollution.

Air Pollutants↗
PubMed2003

Assessment of contaminant diffusivities in building materials from porosimetry tests.

Recent studies have shown that surface and gaseous contaminant interactions may play an important role in indoor air quality. Modeling is an important tool to improve our knowledge about the phenomena involved and define appropriate ventilation strategies. However, data for sorption isotherms and diffusion in building materials remain woefully lacking. This paper deals with the latter point. It aims at investigating a methodology based on an analysis of the material porosity first and then the application of Carniglia's mathematical model to determine the effective diffusivity of gaseous species in building materials. This methodology, whose main principles are presented in the first part of the paper, was applied to seven commonly found materials. Mercury intrusion porosimetry (MIP) tests, and the calculations using Carniglia's model, reveal typical total porosities and tortuosity factors for these materials. The analysis of pore size distributions (PSDs) also draws one's attention to the possible differences in the pore structures that may exist between two samples of the same type of material and the differences in the effective diffusivities of contaminants that may result from them. The computed effective diffusivities were subsequently compared to data from experiments carried out in the frame of the EC project MATHIS. An agreement was obtained, thus validating Carniglia's methodology - a methodology that offers many practical advantages compared to diffusion-cell methods.

Air Pollution, Indoor↗
PubMed2001

Diurnal variation of episcleral venous pressure in healthy patients: a pilot study.

PURPOSE: To study diurnal episcleral venous pressure (EVP) and its relation to intraocular pressure (IOP) in healthy patients. The influences of supine position and lid closure on EVP were also studied. DESIGN: Experimental observational study. PARTICIPANTS AND METHODS: Twelve healthy patients with no eye disease had their IOP and EVP measured at 16h00, 22h00, 22h30, 06h00, 06h30, 09h00, 12h00, and 16h00. Measurements at 22h30, 06h00, and 06h30 were performed on supine patients, and the measurement at 06h00 was with the eye that had been closed for the whole night. In a second experiment, EVP was measured on patients who were lying supine from 22h30 to 16h00 with one eye closed during the day. MAIN OUTCOME MEASURES: Episcleral venous pressure and IOP at varying time points during a 24-hour period. RESULTS: Episcleral venous pressure was relatively constant throughout the day except for a slight reduction at 22h00. After lying down, the EVP increased by 3.6 mm Hg and remained increased as long as the patient remained in this position. Eyelid closure did not affect EVP. IOP measured with the Tono-Pen closely followed the variations in EVP. CONCLUSION: Episcleral venous pressure remains relatively constant throughout the day. It increases in the supine position with a corresponding increase in IOP. Lid closure does not influence EVP or IOP.

Circadian Rhythm↗
PubMed1998

Intraocular pressure change measured by Goldmann tonometry after laser in situ keratomileusis.

PURPOSE: To assess the accuracy of Goldmann tonometry after laser in situ keratomileusis (LASIK). SETTING: University-based refractive surgery group (Clinique du Laser Visuel). METHOD: The database of patients who had LASIK was retrospectively reviewed. Preoperative and postoperative intraocular pressure (IOP) was measured in 145 patients. The correlation between decrease in IOP and various preoperative and intraoperative parameters was evaluated by regression analysis. Only one eye in patients having bilateral surgery was used for statistical analysis. RESULTS: Laser in situ keratomileusis was associated with a mean decrease in IOP of 1.9 mm Hg +/- 2.9 (SD). There was no significant correlation between the decrease and any parameter evaluated. CONCLUSION: Intraocular pressure after LASIK decreased by a mean of 1.9 +/- 2.9 mm Hg. The cause of the decrease remains unknown.

Adult↗
PubMed1994

[Substernal goiter: diagnostic and therapeutic problems (apropos of a personal series of 585 interventions)].

This retrospective study is based on a personal experience of 585 operations performed between 1958 and 1993. The diagnosis and topographic evaluation of the thoracic extension of a goiter were greatly improved by the development of the new imaging technics (CT Scan and RMN). Those rather expansive and complex technics were not necessary in 505 cases (86.3%), the diagnosis and topographic evaluation being easy from the conventional tests (X-ray, echography, scintigraphy). But in 80 cas (13.7%) either the diagnosis or the topographic evaluation were difficult or mistaken because Scan or RMN were not yet available or were not used (20 thoracic extensions overlooked; 26 separated thoracic goiters; 24 crossed thoracic extensions; 5 massive degeneration of thoracic extension; 5 false thoracic extension simulated by a mediastinal tumor). The surgical ablation of the substernal goiter could be achieved through a simple cervical approach in 96.4% of the operations. In 21 cases it appeared necessary to prolong the cervicomy by a median sternotomy (total and extrapleural sternotomy in all cases). The transternal approach was imposed in 9 cases by a profound and voluminous thoracic extension in contrast with a small cervical thyroid. In 5 cases, the reason was a massive malignant degeneration of the thoracic extension. In 7 patients the operation was done for a mediastinal redux after a previous cervical thyroidectomy having overlooked the thoracic extension. In spite of all the difficulties, all operations were successful with no mortality and a low morbidity (although slightly higher than the overall morbidity of thyroid surgery).

Goiter, Substernal↗
PubMed1992

[Is thyroid cancer a severe cancer? (Prognostic study of 800 surgically-treated cases of which 143 nodular differentiated cancers were followed-up for more than 20 years)].

The prognosis of thyroid carcinoma has always been difficult to appreciate because this rather rare carcinoma is polymorph and subject to some very late recurrencies. For these reasons an acceptable prognostic evaluation is only possible with an important material and very long follow-up. From 800 patients operated by the author, 102 (13%) had an extra-capsular tumor, which means for all authors a very poor prognosis. Still two groups must be separated: the anaplastic extracapsular tumors (33/102) gave a very low life expectancy with 17% survival at 5 years and no patient surviving at 8 years. In contrast the differentiated extracapsular tumors, mainly papillary, gave an unexpected survival rate of 35% at 15 years. The more frequent nodular form of differentiated carcinoma (698/800 = 87%) has a much better prognosis, but his slow evolution needs a long follow-up observation. From 160 patients operated on before 1971, 143 (90%) could be all followed during 20 years or more. The over-all survival rate at the 20th year is 83% with 76% of patients free of any recurrence. The analysis of several factors showed that the extension of the primitive operation (lobectomy or total thyroidectomy) does not influence the long term results. More reliable prognostic factors are the degree of histologic differentiation of the tumor, and the age of the patient. Finally, in spite of an excellent overall long-term prognosis, three very late recurrencies were observed in the group of 143 patients followed more than 20 years, respectively 21, 22 and 31 years after the first operation. This makes impossible the certitude of definitive cure of any thyroid cancer.

Cell Differentiation↗
PubMed1991

Embolization of cardiac myxomas masquerading as polyarteritis nodosa.

Cardiac myxomas are rare tumors which can mimic other diseases. We describe a 19-year-old man who presented clinically with polyarteritis nodosa (PAN). Muscle biopsy showed vasculitis, but corticosteroid and immunosuppressive therapy was initially effective. Cardiac myxomas were found by echocardiogram when the disease relapsed and were resected surgically. Segmental arterial aneurysms and stenoses were found on angiography after leg ischemia. We suggest that echocardiography should be performed in all cases of clinically suspected PAN.

Adrenal Cortex Hormones↗
PubMed1991

[Management of subrenal aneurysm of the abdominal aorta].

This update, intended for cardiologists, is not concerned with technical surgical considerations but rather considers the problems facing the physician in abdominal aortic aneurysm (AAA). 1) What form does AAA take: an atheromatous, spindle-shaped and partially thrombotic ectasis. 2) How is it detected: traditionally by clinical examination and increasingly by ultrasound. 3) What additional examinations are useful: the most simple and commonly repeated is ultrasound. Aortic angiography is useful only in cases with a surgical indication. 4) What is the risk of spontaneous development: above all, rupture, the statistical risk of which becomes considerable once the diameter of the aneurysm exceeds 6 cm. 5) What are the risks and results of surgical treatment: it has become an operation presenting little danger and one that beyond all doubt increases life expectancy. 6) Which patients should undergo surgery: all aneurysms dating from more than 6 cm and/or showing symptoms.

Aortic Dissection↗
PubMed1991

[Surgical treatment of hyperthyroidism (therapeutic and nosologic considerations from a personal experience of 2,395 cases)].

A retrospective analysis of the author's surgical experience (2,395 operations) demonstrates that the surgical treatment of hyperthyroid is nowadays simple and benign without mortality and with a very low morbidity. This dramatic improvement can be explained by the combination of a better medical preparation, and a meticulous surgical technic in the hands of an experimented team. The long term results are excellent with no recurrence of hyperthyroid. In about 30% of patients is observed a residual hypothyroid, which is milder, less evolutive and easier to manage than hypothyroid following radio-iodine therapy. Surgery thus appears in most cases to be the best solution, when the impossibility or failure of a medical treatment leads to consider a more radical approach. A classification of hyperthyroid lesions is proposed which seemed more suitable for the establishment of a rational surgical strategy. This classification is based on the opposition of diffuse hyperfunctional hyperplasia (with or without nodes) and localised toxic adenomas (single or multiple).

Humans↗
PubMed1990

Clinical features of adrenocortical carcinoma, prognostic factors, and the effect of mitotane therapy.

Adrenocortical carcinoma is a rare tumor, and only limited information is available about its natural history and the effects of therapy. We studied 105 patients (75 female and 30 male; mean age, 46 years) with adrenocortical carcinoma who were referred to us between 1963 and 1987. The average duration of symptoms before diagnosis was 8.7 months. At the time of diagnosis, 68 percent of the patients had endocrine symptoms, and 30 percent had distant metastases. Hormonal studies showed that 79 percent of the tumors were functional. Eighty patients underwent surgery, and 59 also received the adrenal cytotoxic agent mitotane. The median disease-free interval after surgery was 12.1 months (range, 1 to 175). Tumor dissemination occurred in 82 percent of the patients, most commonly to the lung, liver, and adjacent organs. The median survival time was 14.5 months (range, less than 1 to 175), and the five-year survival was 22 percent. Age over 40 years and the presence of metastases at the time of diagnosis were the only factors recognized as indicating a poor prognosis. Mitotane controlled hormonal secretion in 75 percent of the patients. Eight mitotane-treated patients had partial tumor regression, but the drug did not have a significant effect on survival. We conclude that adrenocortical carcinoma carries a poor prognosis. Mitotane therapy may offer transient benefits, particularly in controlling endocrine symptoms.

Adrenal Cortex Hormones↗
PubMed1990

Ventricular septal defect associated with aortic valve incompetence: results of two surgical managements.

Aortic valve insufficiency with ventricular septal defect is usually treated by plication of the commissures. However, long-term deterioration is common. We propose a new technique that corrects the aortic annulus dilatation and the leaflet prolapse and reinforces the sinus of Valsalva. Two groups were compared: group I (29 patients) had plication of the prolapsed leaflet(s) and folding of the free edge; group II (26 patients) had triangular resection of the prolapse cusp, annuloplasty, and reinforcement of the aortic wall. The two groups were similar with regarding to preoperative clinical data. There was no perioperative mortality. Primary failure (aortic valve replacement) occurred in 8 patients in group I (28%) and in 2 patients in group II (8%). The rate of secondary failure was 31% in group I and 4% in group II. The actuarial rate of freedom from reoperation at 5 years is 55% in group I and 88% in group II (p less than 0.05). The late mortality was 6.5% in group I and 10.9% in group II (no difference). We conclude that aortic valve insufficiency with ventricular septal defect is a malformation of the aortic leaflets, the annulus, and the sinus of Valsalva, and that the proposed technique offers a better result than the usual methods in terms of residual aortic valve insufficiency.

Adolescent↗
PubMed1990

Primary cardiac tumors--French studies of 533 cases.

The present study combining the Eisenman French Joint Study and the Broussais Hospital experience is based upon 533 primary cardiac tumors which were operated on in France and by French-speaking teams during a period of about 25 years. The diagnosis of heart tumors was facilitated by the progressive development of new examination techniques. Echocardiography seems to be the simplest, safest, and the most reliable diagnostic method and is used more frequently then angiocardiography. Cardiac tumors occur at every age with a prevalence for females. About 10% of the surgically treated primary cardiac tumors were malignant (53 patients) with a constantly poor prognosis. The mean survival time of this collective after operation was only 1.5 years. 8% of the benign cardiac tumors were non-myxomatous (36), including fibromas, rhabdomyomas, and hamartomas. The mean age of this group was lower (21 years) than in the collectives with myxomas or with malignant cardiac tumors. Another characteristic of non-myxomatous tumors is the involvement of the ventricles by the neoplasm (88%). Complete resection of the tumor was possible in 75%, only 3 operative deaths occurred. Myxomas are the most common tumors of the heart, representing 83% of all primary cardiac tumors (444). Female patients were involved more often than males. The age of the patients ranged widely from 2.5 to 82 years. The typical localization of the myxomas was the left atrium (83%), followed by the right atrium (11%). In 5 cases myxomas were found multilocalized. Very often myxomas were mimicing valvular disease. In more than 30% peripheral embolization provoked the diagnosis. Only in 2% was the tumor totally asymptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1989

A 10-year comparison of mitral valve replacement with Carpentier-Edwards and Hancock porcine bioprostheses.

Two hundred fifty-three patients who underwent isolated mitral valve replacement with a porcine bioprosthesis had long-term evaluation. One hundred forty-seven patients received a Carpentier-Edwards porcine bioprosthesis and 106, a Hancock valve. There were no significant differences in preoperative clinical characteristics between the two groups. Cumulative follow-up was 1,375 patient-years. At 10 years, 93% +/- 2.5% of the patients in the Carpentier-Edwards group and 85% +/- 7.8% of those in the Hancock group were free from valve-related death (not significant), and 95% +/- 2% and 91% +/- 3.8%, respectively, were free from thromboembolism (not significant). At 10 years, 65% +/- 7.2% of the patients in the Carpentier-Edwards group and 66% +/- 7.2% of those in the Hancock group were free from structural valve deterioration (not significant), and 64% +/- 6% and 59% +/- 7.3%, respectively, were free from reoperation (not significant). We conclude that the first generation of Carpentier-Edwards and Hancock prostheses produce comparable long-term results in the mitral position.

Actuarial Analysis↗
PubMed1988

Clinical comparison of mitral valve replacement using porcine, Starr, and Bjork valves.

The choice of a cardiac prosthesis for mitral valve replacement remains controversial, and thromboembolic complications are still a major cause of morbidity and mortality in patients with mechanical valves. Because of this, permanent anticoagulation with its risks and constraints on daily life is necessary. Bioprostheses, however, are associated with a lower rate of thromboembolic events. Therefore, the need for long-term anticoagulation is minimized. These advantages are counterbalanced by the limited durability of tissue valves. In an effort to give some perspective to this balance, we compared the long-term results of three commonly used mitral valve prostheses. Three hundred patients operated on in the same institution January 1974 to December 1978 form the basis of this evaluation.

Adolescent↗